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divestos-build/Patches/OLD/bacon/Old/android_kernel_oneplus_msm8974/10.patch
Tad c0083c1519 Initial commit, long overdue
2016-12-21 19:30:02 -05:00

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From 308d9fade64b5cd1292f4dceb053cc5ab7a322de Mon Sep 17 00:00:00 2001
From: Tad <tad@spotco.us>
Date: Tue, 26 May 2015 14:05:46 -0400
Subject: [PATCH] Missing files
---
Documentation/lzo.txt | 164 ++
arch/x86/include/asm/espfix.h | 16 +
arch/x86/kernel/espfix_64.c | 208 ++
block/bfq-cgroup.c | 908 +++++++++
block/bfq-ioc.c | 36 +
block/bfq-iosched.c | 4208 +++++++++++++++++++++++++++++++++++++++++
block/bfq-sched.c | 1186 ++++++++++++
block/bfq.h | 809 ++++++++
block/fiops-iosched.c | 753 ++++++++
block/sio-iosched.c | 403 ++++
block/sioplus-iosched.c | 405 ++++
block/tripndroid-iosched.c | 261 +++
block/vr-iosched.c | 432 +++++
block/zen-iosched.c | 277 +++
drivers/md/dm-builtin.c | 50 +
15 files changed, 10116 insertions(+)
create mode 100644 Documentation/lzo.txt
create mode 100644 arch/x86/include/asm/espfix.h
create mode 100644 arch/x86/kernel/espfix_64.c
create mode 100644 block/bfq-cgroup.c
create mode 100644 block/bfq-ioc.c
create mode 100644 block/bfq-iosched.c
create mode 100644 block/bfq-sched.c
create mode 100644 block/bfq.h
create mode 100644 block/fiops-iosched.c
create mode 100644 block/sio-iosched.c
create mode 100644 block/sioplus-iosched.c
create mode 100644 block/tripndroid-iosched.c
create mode 100644 block/vr-iosched.c
create mode 100644 block/zen-iosched.c
create mode 100644 drivers/md/dm-builtin.c
diff --git a/Documentation/lzo.txt b/Documentation/lzo.txt
new file mode 100644
index 0000000..ea45dd3
--- /dev/null
+++ b/Documentation/lzo.txt
@@ -0,0 +1,164 @@
+
+LZO stream format as understood by Linux's LZO decompressor
+===========================================================
+
+Introduction
+
+ This is not a specification. No specification seems to be publicly available
+ for the LZO stream format. This document describes what input format the LZO
+ decompressor as implemented in the Linux kernel understands. The file subject
+ of this analysis is lib/lzo/lzo1x_decompress_safe.c. No analysis was made on
+ the compressor nor on any other implementations though it seems likely that
+ the format matches the standard one. The purpose of this document is to
+ better understand what the code does in order to propose more efficient fixes
+ for future bug reports.
+
+Description
+
+ The stream is composed of a series of instructions, operands, and data. The
+ instructions consist in a few bits representing an opcode, and bits forming
+ the operands for the instruction, whose size and position depend on the
+ opcode and on the number of literals copied by previous instruction. The
+ operands are used to indicate :
+
+ - a distance when copying data from the dictionary (past output buffer)
+ - a length (number of bytes to copy from dictionary)
+ - the number of literals to copy, which is retained in variable "state"
+ as a piece of information for next instructions.
+
+ Optionally depending on the opcode and operands, extra data may follow. These
+ extra data can be a complement for the operand (eg: a length or a distance
+ encoded on larger values), or a literal to be copied to the output buffer.
+
+ The first byte of the block follows a different encoding from other bytes, it
+ seems to be optimized for literal use only, since there is no dictionary yet
+ prior to that byte.
+
+ Lengths are always encoded on a variable size starting with a small number
+ of bits in the operand. If the number of bits isn't enough to represent the
+ length, up to 255 may be added in increments by consuming more bytes with a
+ rate of at most 255 per extra byte (thus the compression ratio cannot exceed
+ around 255:1). The variable length encoding using #bits is always the same :
+
+ length = byte & ((1 << #bits) - 1)
+ if (!length) {
+ length = ((1 << #bits) - 1)
+ length += 255*(number of zero bytes)
+ length += first-non-zero-byte
+ }
+ length += constant (generally 2 or 3)
+
+ For references to the dictionary, distances are relative to the output
+ pointer. Distances are encoded using very few bits belonging to certain
+ ranges, resulting in multiple copy instructions using different encodings.
+ Certain encodings involve one extra byte, others involve two extra bytes
+ forming a little-endian 16-bit quantity (marked LE16 below).
+
+ After any instruction except the large literal copy, 0, 1, 2 or 3 literals
+ are copied before starting the next instruction. The number of literals that
+ were copied may change the meaning and behaviour of the next instruction. In
+ practice, only one instruction needs to know whether 0, less than 4, or more
+ literals were copied. This is the information stored in the <state> variable
+ in this implementation. This number of immediate literals to be copied is
+ generally encoded in the last two bits of the instruction but may also be
+ taken from the last two bits of an extra operand (eg: distance).
+
+ End of stream is declared when a block copy of distance 0 is seen. Only one
+ instruction may encode this distance (0001HLLL), it takes one LE16 operand
+ for the distance, thus requiring 3 bytes.
+
+ IMPORTANT NOTE : in the code some length checks are missing because certain
+ instructions are called under the assumption that a certain number of bytes
+ follow because it has already been garanteed before parsing the instructions.
+ They just have to "refill" this credit if they consume extra bytes. This is
+ an implementation design choice independant on the algorithm or encoding.
+
+Byte sequences
+
+ First byte encoding :
+
+ 0..17 : follow regular instruction encoding, see below. It is worth
+ noting that codes 16 and 17 will represent a block copy from
+ the dictionary which is empty, and that they will always be
+ invalid at this place.
+
+ 18..21 : copy 0..3 literals
+ state = (byte - 17) = 0..3 [ copy <state> literals ]
+ skip byte
+
+ 22..255 : copy literal string
+ length = (byte - 17) = 4..238
+ state = 4 [ don't copy extra literals ]
+ skip byte
+
+ Instruction encoding :
+
+ 0 0 0 0 X X X X (0..15)
+ Depends on the number of literals copied by the last instruction.
+ If last instruction did not copy any literal (state == 0), this
+ encoding will be a copy of 4 or more literal, and must be interpreted
+ like this :
+
+ 0 0 0 0 L L L L (0..15) : copy long literal string
+ length = 3 + (L ?: 15 + (zero_bytes * 255) + non_zero_byte)
+ state = 4 (no extra literals are copied)
+
+ If last instruction used to copy between 1 to 3 literals (encoded in
+ the instruction's opcode or distance), the instruction is a copy of a
+ 2-byte block from the dictionary within a 1kB distance. It is worth
+ noting that this instruction provides little savings since it uses 2
+ bytes to encode a copy of 2 other bytes but it encodes the number of
+ following literals for free. It must be interpreted like this :
+
+ 0 0 0 0 D D S S (0..15) : copy 2 bytes from <= 1kB distance
+ length = 2
+ state = S (copy S literals after this block)
+ Always followed by exactly one byte : H H H H H H H H
+ distance = (H << 2) + D + 1
+
+ If last instruction used to copy 4 or more literals (as detected by
+ state == 4), the instruction becomes a copy of a 3-byte block from the
+ dictionary from a 2..3kB distance, and must be interpreted like this :
+
+ 0 0 0 0 D D S S (0..15) : copy 3 bytes from 2..3 kB distance
+ length = 3
+ state = S (copy S literals after this block)
+ Always followed by exactly one byte : H H H H H H H H
+ distance = (H << 2) + D + 2049
+
+ 0 0 0 1 H L L L (16..31)
+ Copy of a block within 16..48kB distance (preferably less than 10B)
+ length = 2 + (L ?: 7 + (zero_bytes * 255) + non_zero_byte)
+ Always followed by exactly one LE16 : D D D D D D D D : D D D D D D S S
+ distance = 16384 + (H << 14) + D
+ state = S (copy S literals after this block)
+ End of stream is reached if distance == 16384
+
+ 0 0 1 L L L L L (32..63)
+ Copy of small block within 16kB distance (preferably less than 34B)
+ length = 2 + (L ?: 31 + (zero_bytes * 255) + non_zero_byte)
+ Always followed by exactly one LE16 : D D D D D D D D : D D D D D D S S
+ distance = D + 1
+ state = S (copy S literals after this block)
+
+ 0 1 L D D D S S (64..127)
+ Copy 3-4 bytes from block within 2kB distance
+ state = S (copy S literals after this block)
+ length = 3 + L
+ Always followed by exactly one byte : H H H H H H H H
+ distance = (H << 3) + D + 1
+
+ 1 L L D D D S S (128..255)
+ Copy 5-8 bytes from block within 2kB distance
+ state = S (copy S literals after this block)
+ length = 5 + L
+ Always followed by exactly one byte : H H H H H H H H
+ distance = (H << 3) + D + 1
+
+Authors
+
+ This document was written by Willy Tarreau <w@1wt.eu> on 2014/07/19 during an
+ analysis of the decompression code available in Linux 3.16-rc5. The code is
+ tricky, it is possible that this document contains mistakes or that a few
+ corner cases were overlooked. In any case, please report any doubt, fix, or
+ proposed updates to the author(s) so that the document can be updated.
diff --git a/arch/x86/include/asm/espfix.h b/arch/x86/include/asm/espfix.h
new file mode 100644
index 0000000..99efebb
--- /dev/null
+++ b/arch/x86/include/asm/espfix.h
@@ -0,0 +1,16 @@
+#ifndef _ASM_X86_ESPFIX_H
+#define _ASM_X86_ESPFIX_H
+
+#ifdef CONFIG_X86_64
+
+#include <asm/percpu.h>
+
+DECLARE_PER_CPU_READ_MOSTLY(unsigned long, espfix_stack);
+DECLARE_PER_CPU_READ_MOSTLY(unsigned long, espfix_waddr);
+
+extern void init_espfix_bsp(void);
+extern void init_espfix_ap(void);
+
+#endif /* CONFIG_X86_64 */
+
+#endif /* _ASM_X86_ESPFIX_H */
diff --git a/arch/x86/kernel/espfix_64.c b/arch/x86/kernel/espfix_64.c
new file mode 100644
index 0000000..94d857f
--- /dev/null
+++ b/arch/x86/kernel/espfix_64.c
@@ -0,0 +1,208 @@
+/* ----------------------------------------------------------------------- *
+ *
+ * Copyright 2014 Intel Corporation; author: H. Peter Anvin
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * The IRET instruction, when returning to a 16-bit segment, only
+ * restores the bottom 16 bits of the user space stack pointer. This
+ * causes some 16-bit software to break, but it also leaks kernel state
+ * to user space.
+ *
+ * This works around this by creating percpu "ministacks", each of which
+ * is mapped 2^16 times 64K apart. When we detect that the return SS is
+ * on the LDT, we copy the IRET frame to the ministack and use the
+ * relevant alias to return to userspace. The ministacks are mapped
+ * readonly, so if the IRET fault we promote #GP to #DF which is an IST
+ * vector and thus has its own stack; we then do the fixup in the #DF
+ * handler.
+ *
+ * This file sets up the ministacks and the related page tables. The
+ * actual ministack invocation is in entry_64.S.
+ */
+
+#include <linux/init.h>
+#include <linux/init_task.h>
+#include <linux/kernel.h>
+#include <linux/percpu.h>
+#include <linux/gfp.h>
+#include <linux/random.h>
+#include <asm/pgtable.h>
+#include <asm/pgalloc.h>
+#include <asm/setup.h>
+#include <asm/espfix.h>
+
+/*
+ * Note: we only need 6*8 = 48 bytes for the espfix stack, but round
+ * it up to a cache line to avoid unnecessary sharing.
+ */
+#define ESPFIX_STACK_SIZE (8*8UL)
+#define ESPFIX_STACKS_PER_PAGE (PAGE_SIZE/ESPFIX_STACK_SIZE)
+
+/* There is address space for how many espfix pages? */
+#define ESPFIX_PAGE_SPACE (1UL << (PGDIR_SHIFT-PAGE_SHIFT-16))
+
+#define ESPFIX_MAX_CPUS (ESPFIX_STACKS_PER_PAGE * ESPFIX_PAGE_SPACE)
+#if CONFIG_NR_CPUS > ESPFIX_MAX_CPUS
+# error "Need more than one PGD for the ESPFIX hack"
+#endif
+
+#define PGALLOC_GFP (GFP_KERNEL | __GFP_NOTRACK | __GFP_REPEAT | __GFP_ZERO)
+
+/* This contains the *bottom* address of the espfix stack */
+DEFINE_PER_CPU_READ_MOSTLY(unsigned long, espfix_stack);
+DEFINE_PER_CPU_READ_MOSTLY(unsigned long, espfix_waddr);
+
+/* Initialization mutex - should this be a spinlock? */
+static DEFINE_MUTEX(espfix_init_mutex);
+
+/* Page allocation bitmap - each page serves ESPFIX_STACKS_PER_PAGE CPUs */
+#define ESPFIX_MAX_PAGES DIV_ROUND_UP(CONFIG_NR_CPUS, ESPFIX_STACKS_PER_PAGE)
+static void *espfix_pages[ESPFIX_MAX_PAGES];
+
+static __page_aligned_bss pud_t espfix_pud_page[PTRS_PER_PUD]
+ __aligned(PAGE_SIZE);
+
+static unsigned int page_random, slot_random;
+
+/*
+ * This returns the bottom address of the espfix stack for a specific CPU.
+ * The math allows for a non-power-of-two ESPFIX_STACK_SIZE, in which case
+ * we have to account for some amount of padding at the end of each page.
+ */
+static inline unsigned long espfix_base_addr(unsigned int cpu)
+{
+ unsigned long page, slot;
+ unsigned long addr;
+
+ page = (cpu / ESPFIX_STACKS_PER_PAGE) ^ page_random;
+ slot = (cpu + slot_random) % ESPFIX_STACKS_PER_PAGE;
+ addr = (page << PAGE_SHIFT) + (slot * ESPFIX_STACK_SIZE);
+ addr = (addr & 0xffffUL) | ((addr & ~0xffffUL) << 16);
+ addr += ESPFIX_BASE_ADDR;
+ return addr;
+}
+
+#define PTE_STRIDE (65536/PAGE_SIZE)
+#define ESPFIX_PTE_CLONES (PTRS_PER_PTE/PTE_STRIDE)
+#define ESPFIX_PMD_CLONES PTRS_PER_PMD
+#define ESPFIX_PUD_CLONES (65536/(ESPFIX_PTE_CLONES*ESPFIX_PMD_CLONES))
+
+#define PGTABLE_PROT ((_KERNPG_TABLE & ~_PAGE_RW) | _PAGE_NX)
+
+static void init_espfix_random(void)
+{
+ unsigned long rand;
+
+ /*
+ * This is run before the entropy pools are initialized,
+ * but this is hopefully better than nothing.
+ */
+ if (!arch_get_random_long(&rand)) {
+ /* The constant is an arbitrary large prime */
+ rdtscll(rand);
+ rand *= 0xc345c6b72fd16123UL;
+ }
+
+ slot_random = rand % ESPFIX_STACKS_PER_PAGE;
+ page_random = (rand / ESPFIX_STACKS_PER_PAGE)
+ & (ESPFIX_PAGE_SPACE - 1);
+}
+
+void __init init_espfix_bsp(void)
+{
+ pgd_t *pgd_p;
+ pteval_t ptemask;
+
+ ptemask = __supported_pte_mask;
+
+ /* Install the espfix pud into the kernel page directory */
+ pgd_p = &init_level4_pgt[pgd_index(ESPFIX_BASE_ADDR)];
+ pgd_populate(&init_mm, pgd_p, (pud_t *)espfix_pud_page);
+
+ /* Randomize the locations */
+ init_espfix_random();
+
+ /* The rest is the same as for any other processor */
+ init_espfix_ap();
+}
+
+void init_espfix_ap(void)
+{
+ unsigned int cpu, page;
+ unsigned long addr;
+ pud_t pud, *pud_p;
+ pmd_t pmd, *pmd_p;
+ pte_t pte, *pte_p;
+ int n;
+ void *stack_page;
+ pteval_t ptemask;
+
+ /* We only have to do this once... */
+ if (likely(this_cpu_read(espfix_stack)))
+ return; /* Already initialized */
+
+ cpu = smp_processor_id();
+ addr = espfix_base_addr(cpu);
+ page = cpu/ESPFIX_STACKS_PER_PAGE;
+
+ /* Did another CPU already set this up? */
+ stack_page = ACCESS_ONCE(espfix_pages[page]);
+ if (likely(stack_page))
+ goto done;
+
+ mutex_lock(&espfix_init_mutex);
+
+ /* Did we race on the lock? */
+ stack_page = ACCESS_ONCE(espfix_pages[page]);
+ if (stack_page)
+ goto unlock_done;
+
+ ptemask = __supported_pte_mask;
+
+ pud_p = &espfix_pud_page[pud_index(addr)];
+ pud = *pud_p;
+ if (!pud_present(pud)) {
+ pmd_p = (pmd_t *)__get_free_page(PGALLOC_GFP);
+ pud = __pud(__pa(pmd_p) | (PGTABLE_PROT & ptemask));
+ paravirt_alloc_pmd(&init_mm, __pa(pmd_p) >> PAGE_SHIFT);
+ for (n = 0; n < ESPFIX_PUD_CLONES; n++)
+ set_pud(&pud_p[n], pud);
+ }
+
+ pmd_p = pmd_offset(&pud, addr);
+ pmd = *pmd_p;
+ if (!pmd_present(pmd)) {
+ pte_p = (pte_t *)__get_free_page(PGALLOC_GFP);
+ pmd = __pmd(__pa(pte_p) | (PGTABLE_PROT & ptemask));
+ paravirt_alloc_pte(&init_mm, __pa(pte_p) >> PAGE_SHIFT);
+ for (n = 0; n < ESPFIX_PMD_CLONES; n++)
+ set_pmd(&pmd_p[n], pmd);
+ }
+
+ pte_p = pte_offset_kernel(&pmd, addr);
+ stack_page = (void *)__get_free_page(GFP_KERNEL);
+ pte = __pte(__pa(stack_page) | (__PAGE_KERNEL_RO & ptemask));
+ for (n = 0; n < ESPFIX_PTE_CLONES; n++)
+ set_pte(&pte_p[n*PTE_STRIDE], pte);
+
+ /* Job is done for this CPU and any CPU which shares this page */
+ ACCESS_ONCE(espfix_pages[page]) = stack_page;
+
+unlock_done:
+ mutex_unlock(&espfix_init_mutex);
+done:
+ this_cpu_write(espfix_stack, addr);
+ this_cpu_write(espfix_waddr, (unsigned long)stack_page
+ + (addr & ~PAGE_MASK));
+}
diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
new file mode 100644
index 0000000..8399c92
--- /dev/null
+++ b/block/bfq-cgroup.c
@@ -0,0 +1,908 @@
+/*
+ * BFQ: CGROUPS support.
+ *
+ * Based on ideas and code from CFQ:
+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
+ *
+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
+ * Paolo Valente <paolo.valente@unimore.it>
+ *
+ * Copyright (C) 2010 Paolo Valente <paolo.valente@unimore.it>
+ *
+ * Licensed under the GPL-2 as detailed in the accompanying COPYING.BFQ
+ * file.
+ */
+
+#ifdef CONFIG_CGROUP_BFQIO
+static struct bfqio_cgroup bfqio_root_cgroup = {
+ .weight = BFQ_DEFAULT_GRP_WEIGHT,
+ .ioprio = BFQ_DEFAULT_GRP_IOPRIO,
+ .ioprio_class = BFQ_DEFAULT_GRP_CLASS,
+};
+
+static inline void bfq_init_entity(struct bfq_entity *entity,
+ struct bfq_group *bfqg)
+{
+ entity->weight = entity->new_weight;
+ entity->orig_weight = entity->new_weight;
+ entity->ioprio = entity->new_ioprio;
+ entity->ioprio_class = entity->new_ioprio_class;
+ entity->parent = bfqg->my_entity;
+ entity->sched_data = &bfqg->sched_data;
+}
+
+static struct bfqio_cgroup *cgroup_to_bfqio(struct cgroup *cgroup)
+{
+ return container_of(cgroup_subsys_state(cgroup, bfqio_subsys_id),
+ struct bfqio_cgroup, css);
+}
+
+/*
+ * Search the bfq_group for bfqd into the hash table (by now only a list)
+ * of bgrp. Must be called under rcu_read_lock().
+ */
+static struct bfq_group *bfqio_lookup_group(struct bfqio_cgroup *bgrp,
+ struct bfq_data *bfqd)
+{
+ struct bfq_group *bfqg;
+ struct hlist_node *n;
+ void *key;
+
+ hlist_for_each_entry_rcu(bfqg, n, &bgrp->group_data, group_node) {
+ key = rcu_dereference(bfqg->bfqd);
+ if (key == bfqd)
+ return bfqg;
+ }
+
+ return NULL;
+}
+
+static inline void bfq_group_init_entity(struct bfqio_cgroup *bgrp,
+ struct bfq_group *bfqg)
+{
+ struct bfq_entity *entity = &bfqg->entity;
+
+ /*
+ * If the weight of the entity has never been set via the sysfs
+ * interface, then bgrp->weight == 0. In this case we initialize
+ * the weight from the current ioprio value. Otherwise, the group
+ * weight, if set, has priority over the ioprio value.
+ */
+ if (bgrp->weight == 0) {
+ entity->new_weight = bfq_ioprio_to_weight(bgrp->ioprio);
+ entity->new_ioprio = bgrp->ioprio;
+ } else {
+ if (bgrp->weight < BFQ_MIN_WEIGHT ||
+ bgrp->weight > BFQ_MAX_WEIGHT) {
+ printk(KERN_CRIT "bfq_group_init_entity: "
+ "bgrp->weight %d\n", bgrp->weight);
+ BUG();
+ }
+ entity->new_weight = bgrp->weight;
+ entity->new_ioprio = bfq_weight_to_ioprio(bgrp->weight);
+ }
+ entity->orig_weight = entity->weight = entity->new_weight;
+ entity->ioprio = entity->new_ioprio;
+ entity->ioprio_class = entity->new_ioprio_class = bgrp->ioprio_class;
+ entity->my_sched_data = &bfqg->sched_data;
+ bfqg->active_entities = 0;
+}
+
+static inline void bfq_group_set_parent(struct bfq_group *bfqg,
+ struct bfq_group *parent)
+{
+ struct bfq_entity *entity;
+
+ BUG_ON(parent == NULL);
+ BUG_ON(bfqg == NULL);
+
+ entity = &bfqg->entity;
+ entity->parent = parent->my_entity;
+ entity->sched_data = &parent->sched_data;
+}
+
+/**
+ * bfq_group_chain_alloc - allocate a chain of groups.
+ * @bfqd: queue descriptor.
+ * @cgroup: the leaf cgroup this chain starts from.
+ *
+ * Allocate a chain of groups starting from the one belonging to
+ * @cgroup up to the root cgroup. Stop if a cgroup on the chain
+ * to the root has already an allocated group on @bfqd.
+ */
+static struct bfq_group *bfq_group_chain_alloc(struct bfq_data *bfqd,
+ struct cgroup *cgroup)
+{
+ struct bfqio_cgroup *bgrp;
+ struct bfq_group *bfqg, *prev = NULL, *leaf = NULL;
+
+ for (; cgroup != NULL; cgroup = cgroup->parent) {
+ bgrp = cgroup_to_bfqio(cgroup);
+
+ bfqg = bfqio_lookup_group(bgrp, bfqd);
+ if (bfqg != NULL) {
+ /*
+ * All the cgroups in the path from there to the
+ * root must have a bfq_group for bfqd, so we don't
+ * need any more allocations.
+ */
+ break;
+ }
+
+ bfqg = kzalloc(sizeof(*bfqg), GFP_ATOMIC);
+ if (bfqg == NULL)
+ goto cleanup;
+
+ bfq_group_init_entity(bgrp, bfqg);
+ bfqg->my_entity = &bfqg->entity;
+
+ if (leaf == NULL) {
+ leaf = bfqg;
+ prev = leaf;
+ } else {
+ bfq_group_set_parent(prev, bfqg);
+ /*
+ * Build a list of allocated nodes using the bfqd
+ * filed, that is still unused and will be
+ * initialized only after the node will be
+ * connected.
+ */
+ prev->bfqd = bfqg;
+ prev = bfqg;
+ }
+ }
+
+ return leaf;
+
+cleanup:
+ while (leaf != NULL) {
+ prev = leaf;
+ leaf = leaf->bfqd;
+ kfree(prev);
+ }
+
+ return NULL;
+}
+
+/**
+ * bfq_group_chain_link - link an allocated group chain to a cgroup
+ * hierarchy.
+ * @bfqd: the queue descriptor.
+ * @cgroup: the leaf cgroup to start from.
+ * @leaf: the leaf group (to be associated to @cgroup).
+ *
+ * Try to link a chain of groups to a cgroup hierarchy, connecting the
+ * nodes bottom-up, so we can be sure that when we find a cgroup in the
+ * hierarchy that already as a group associated to @bfqd all the nodes
+ * in the path to the root cgroup have one too.
+ *
+ * On locking: the queue lock protects the hierarchy (there is a hierarchy
+ * per device) while the bfqio_cgroup lock protects the list of groups
+ * belonging to the same cgroup.
+ */
+static void bfq_group_chain_link(struct bfq_data *bfqd, struct cgroup *cgroup,
+ struct bfq_group *leaf)
+{
+ struct bfqio_cgroup *bgrp;
+ struct bfq_group *bfqg, *next, *prev = NULL;
+ unsigned long flags;
+
+ assert_spin_locked(bfqd->queue->queue_lock);
+
+ for (; cgroup != NULL && leaf != NULL; cgroup = cgroup->parent) {
+ bgrp = cgroup_to_bfqio(cgroup);
+ next = leaf->bfqd;
+
+ bfqg = bfqio_lookup_group(bgrp, bfqd);
+ BUG_ON(bfqg != NULL);
+
+ spin_lock_irqsave(&bgrp->lock, flags);
+
+ rcu_assign_pointer(leaf->bfqd, bfqd);
+ hlist_add_head_rcu(&leaf->group_node, &bgrp->group_data);
+ hlist_add_head(&leaf->bfqd_node, &bfqd->group_list);
+
+ spin_unlock_irqrestore(&bgrp->lock, flags);
+
+ prev = leaf;
+ leaf = next;
+ }
+
+ BUG_ON(cgroup == NULL && leaf != NULL);
+ if (cgroup != NULL && prev != NULL) {
+ bgrp = cgroup_to_bfqio(cgroup);
+ bfqg = bfqio_lookup_group(bgrp, bfqd);
+ bfq_group_set_parent(prev, bfqg);
+ }
+}
+
+/**
+ * bfq_find_alloc_group - return the group associated to @bfqd in @cgroup.
+ * @bfqd: queue descriptor.
+ * @cgroup: cgroup being searched for.
+ *
+ * Return a group associated to @bfqd in @cgroup, allocating one if
+ * necessary. When a group is returned all the cgroups in the path
+ * to the root have a group associated to @bfqd.
+ *
+ * If the allocation fails, return the root group: this breaks guarantees
+ * but is a safe fallback. If this loss becomes a problem it can be
+ * mitigated using the equivalent weight (given by the product of the
+ * weights of the groups in the path from @group to the root) in the
+ * root scheduler.
+ *
+ * We allocate all the missing nodes in the path from the leaf cgroup
+ * to the root and we connect the nodes only after all the allocations
+ * have been successful.
+ */
+static struct bfq_group *bfq_find_alloc_group(struct bfq_data *bfqd,
+ struct cgroup *cgroup)
+{
+ struct bfqio_cgroup *bgrp = cgroup_to_bfqio(cgroup);
+ struct bfq_group *bfqg;
+
+ bfqg = bfqio_lookup_group(bgrp, bfqd);
+ if (bfqg != NULL)
+ return bfqg;
+
+ bfqg = bfq_group_chain_alloc(bfqd, cgroup);
+ if (bfqg != NULL)
+ bfq_group_chain_link(bfqd, cgroup, bfqg);
+ else
+ bfqg = bfqd->root_group;
+
+ return bfqg;
+}
+
+/**
+ * bfq_bfqq_move - migrate @bfqq to @bfqg.
+ * @bfqd: queue descriptor.
+ * @bfqq: the queue to move.
+ * @entity: @bfqq's entity.
+ * @bfqg: the group to move to.
+ *
+ * Move @bfqq to @bfqg, deactivating it from its old group and reactivating
+ * it on the new one. Avoid putting the entity on the old group idle tree.
+ *
+ * Must be called under the queue lock; the cgroup owning @bfqg must
+ * not disappear (by now this just means that we are called under
+ * rcu_read_lock()).
+ */
+static void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ struct bfq_entity *entity, struct bfq_group *bfqg)
+{
+ int busy, resume;
+
+ busy = bfq_bfqq_busy(bfqq);
+ resume = !RB_EMPTY_ROOT(&bfqq->sort_list);
+
+ BUG_ON(resume && !entity->on_st);
+ BUG_ON(busy && !resume && entity->on_st &&
+ bfqq != bfqd->in_service_queue);
+
+ if (busy) {
+ BUG_ON(atomic_read(&bfqq->ref) < 2);
+
+ if (!resume)
+ bfq_del_bfqq_busy(bfqd, bfqq, 0);
+ else
+ bfq_deactivate_bfqq(bfqd, bfqq, 0);
+ } else if (entity->on_st)
+ bfq_put_idle_entity(bfq_entity_service_tree(entity), entity);
+
+ /*
+ * Here we use a reference to bfqg. We don't need a refcounter
+ * as the cgroup reference will not be dropped, so that its
+ * destroy() callback will not be invoked.
+ */
+ entity->parent = bfqg->my_entity;
+ entity->sched_data = &bfqg->sched_data;
+
+ if (busy && resume)
+ bfq_activate_bfqq(bfqd, bfqq);
+
+ if (bfqd->in_service_queue == NULL && !bfqd->rq_in_driver)
+ bfq_schedule_dispatch(bfqd);
+}
+
+/**
+ * __bfq_bic_change_cgroup - move @bic to @cgroup.
+ * @bfqd: the queue descriptor.
+ * @bic: the bic to move.
+ * @cgroup: the cgroup to move to.
+ *
+ * Move bic to cgroup, assuming that bfqd->queue is locked; the caller
+ * has to make sure that the reference to cgroup is valid across the call.
+ *
+ * NOTE: an alternative approach might have been to store the current
+ * cgroup in bfqq and getting a reference to it, reducing the lookup
+ * time here, at the price of slightly more complex code.
+ */
+static struct bfq_group *__bfq_bic_change_cgroup(struct bfq_data *bfqd,
+ struct bfq_io_cq *bic,
+ struct cgroup *cgroup)
+{
+ struct bfq_queue *async_bfqq = bic_to_bfqq(bic, 0);
+ struct bfq_queue *sync_bfqq = bic_to_bfqq(bic, 1);
+ struct bfq_entity *entity;
+ struct bfq_group *bfqg;
+ struct bfqio_cgroup *bgrp;
+
+ bgrp = cgroup_to_bfqio(cgroup);
+
+ bfqg = bfq_find_alloc_group(bfqd, cgroup);
+ if (async_bfqq != NULL) {
+ entity = &async_bfqq->entity;
+
+ if (entity->sched_data != &bfqg->sched_data) {
+ bic_set_bfqq(bic, NULL, 0);
+ bfq_log_bfqq(bfqd, async_bfqq,
+ "bic_change_group: %p %d",
+ async_bfqq, atomic_read(&async_bfqq->ref));
+ bfq_put_queue(async_bfqq);
+ }
+ }
+
+ if (sync_bfqq != NULL) {
+ entity = &sync_bfqq->entity;
+ if (entity->sched_data != &bfqg->sched_data)
+ bfq_bfqq_move(bfqd, sync_bfqq, entity, bfqg);
+ }
+
+ return bfqg;
+}
+
+/**
+ * bfq_bic_change_cgroup - move @bic to @cgroup.
+ * @bic: the bic being migrated.
+ * @cgroup: the destination cgroup.
+ *
+ * When the task owning @bic is moved to @cgroup, @bic is immediately
+ * moved into its new parent group.
+ */
+static void bfq_bic_change_cgroup(struct bfq_io_cq *bic,
+ struct cgroup *cgroup)
+{
+ struct bfq_data *bfqd;
+ unsigned long uninitialized_var(flags);
+
+ bfqd = bfq_get_bfqd_locked(&(bic->icq.q->elevator->elevator_data),
+ &flags);
+ if (bfqd != NULL) {
+ __bfq_bic_change_cgroup(bfqd, bic, cgroup);
+ bfq_put_bfqd_unlock(bfqd, &flags);
+ }
+}
+
+/**
+ * bfq_bic_update_cgroup - update the cgroup of @bic.
+ * @bic: the @bic to update.
+ *
+ * Make sure that @bic is enqueued in the cgroup of the current task.
+ * We need this in addition to moving bics during the cgroup attach
+ * phase because the task owning @bic could be at its first disk
+ * access or we may end up in the root cgroup as the result of a
+ * memory allocation failure and here we try to move to the right
+ * group.
+ *
+ * Must be called under the queue lock. It is safe to use the returned
+ * value even after the rcu_read_unlock() as the migration/destruction
+ * paths act under the queue lock too. IOW it is impossible to race with
+ * group migration/destruction and end up with an invalid group as:
+ * a) here cgroup has not yet been destroyed, nor its destroy callback
+ * has started execution, as current holds a reference to it,
+ * b) if it is destroyed after rcu_read_unlock() [after current is
+ * migrated to a different cgroup] its attach() callback will have
+ * taken care of remove all the references to the old cgroup data.
+ */
+static struct bfq_group *bfq_bic_update_cgroup(struct bfq_io_cq *bic)
+{
+ struct bfq_data *bfqd = bic_to_bfqd(bic);
+ struct bfq_group *bfqg;
+ struct cgroup *cgroup;
+
+ BUG_ON(bfqd == NULL);
+
+ rcu_read_lock();
+ cgroup = task_cgroup(current, bfqio_subsys_id);
+ bfqg = __bfq_bic_change_cgroup(bfqd, bic, cgroup);
+ rcu_read_unlock();
+
+ return bfqg;
+}
+
+/**
+ * bfq_flush_idle_tree - deactivate any entity on the idle tree of @st.
+ * @st: the service tree being flushed.
+ */
+static inline void bfq_flush_idle_tree(struct bfq_service_tree *st)
+{
+ struct bfq_entity *entity = st->first_idle;
+
+ for (; entity != NULL; entity = st->first_idle)
+ __bfq_deactivate_entity(entity, 0);
+}
+
+/**
+ * bfq_reparent_leaf_entity - move leaf entity to the root_group.
+ * @bfqd: the device data structure with the root group.
+ * @entity: the entity to move.
+ */
+static inline void bfq_reparent_leaf_entity(struct bfq_data *bfqd,
+ struct bfq_entity *entity)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+
+ BUG_ON(bfqq == NULL);
+ bfq_bfqq_move(bfqd, bfqq, entity, bfqd->root_group);
+ return;
+}
+
+/**
+ * bfq_reparent_active_entities - move to the root group all active
+ * entities.
+ * @bfqd: the device data structure with the root group.
+ * @bfqg: the group to move from.
+ * @st: the service tree with the entities.
+ *
+ * Needs queue_lock to be taken and reference to be valid over the call.
+ */
+static inline void bfq_reparent_active_entities(struct bfq_data *bfqd,
+ struct bfq_group *bfqg,
+ struct bfq_service_tree *st)
+{
+ struct rb_root *active = &st->active;
+ struct bfq_entity *entity = NULL;
+
+ if (!RB_EMPTY_ROOT(&st->active))
+ entity = bfq_entity_of(rb_first(active));
+
+ for (; entity != NULL; entity = bfq_entity_of(rb_first(active)))
+ bfq_reparent_leaf_entity(bfqd, entity);
+
+ if (bfqg->sched_data.in_service_entity != NULL)
+ bfq_reparent_leaf_entity(bfqd,
+ bfqg->sched_data.in_service_entity);
+
+ return;
+}
+
+/**
+ * bfq_destroy_group - destroy @bfqg.
+ * @bgrp: the bfqio_cgroup containing @bfqg.
+ * @bfqg: the group being destroyed.
+ *
+ * Destroy @bfqg, making sure that it is not referenced from its parent.
+ */
+static void bfq_destroy_group(struct bfqio_cgroup *bgrp, struct bfq_group *bfqg)
+{
+ struct bfq_data *bfqd;
+ struct bfq_service_tree *st;
+ struct bfq_entity *entity = bfqg->my_entity;
+ unsigned long uninitialized_var(flags);
+ int i;
+
+ hlist_del(&bfqg->group_node);
+
+ /*
+ * Empty all service_trees belonging to this group before
+ * deactivating the group itself.
+ */
+ for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) {
+ st = bfqg->sched_data.service_tree + i;
+
+ /*
+ * The idle tree may still contain bfq_queues belonging
+ * to exited task because they never migrated to a different
+ * cgroup from the one being destroyed now. No one else
+ * can access them so it's safe to act without any lock.
+ */
+ bfq_flush_idle_tree(st);
+
+ /*
+ * It may happen that some queues are still active
+ * (busy) upon group destruction (if the corresponding
+ * processes have been forced to terminate). We move
+ * all the leaf entities corresponding to these queues
+ * to the root_group.
+ * Also, it may happen that the group has an entity
+ * in service, which is disconnected from the active
+ * tree: it must be moved, too.
+ * There is no need to put the sync queues, as the
+ * scheduler has taken no reference.
+ */
+ bfqd = bfq_get_bfqd_locked(&bfqg->bfqd, &flags);
+ if (bfqd != NULL) {
+ bfq_reparent_active_entities(bfqd, bfqg, st);
+ bfq_put_bfqd_unlock(bfqd, &flags);
+ }
+ BUG_ON(!RB_EMPTY_ROOT(&st->active));
+ BUG_ON(!RB_EMPTY_ROOT(&st->idle));
+ }
+ BUG_ON(bfqg->sched_data.next_in_service != NULL);
+ BUG_ON(bfqg->sched_data.in_service_entity != NULL);
+
+ /*
+ * We may race with device destruction, take extra care when
+ * dereferencing bfqg->bfqd.
+ */
+ bfqd = bfq_get_bfqd_locked(&bfqg->bfqd, &flags);
+ if (bfqd != NULL) {
+ hlist_del(&bfqg->bfqd_node);
+ __bfq_deactivate_entity(entity, 0);
+ bfq_put_async_queues(bfqd, bfqg);
+ bfq_put_bfqd_unlock(bfqd, &flags);
+ }
+ BUG_ON(entity->tree != NULL);
+
+ /*
+ * No need to defer the kfree() to the end of the RCU grace
+ * period: we are called from the destroy() callback of our
+ * cgroup, so we can be sure that no one is a) still using
+ * this cgroup or b) doing lookups in it.
+ */
+ kfree(bfqg);
+}
+
+static void bfq_end_wr_async(struct bfq_data *bfqd)
+{
+ struct hlist_node *pos, *n;
+ struct bfq_group *bfqg;
+
+ hlist_for_each_entry_safe(bfqg, pos, n, &bfqd->group_list, bfqd_node)
+ bfq_end_wr_async_queues(bfqd, bfqg);
+ bfq_end_wr_async_queues(bfqd, bfqd->root_group);
+}
+
+/**
+ * bfq_disconnect_groups - disconnect @bfqd from all its groups.
+ * @bfqd: the device descriptor being exited.
+ *
+ * When the device exits we just make sure that no lookup can return
+ * the now unused group structures. They will be deallocated on cgroup
+ * destruction.
+ */
+static void bfq_disconnect_groups(struct bfq_data *bfqd)
+{
+ struct hlist_node *pos, *n;
+ struct bfq_group *bfqg;
+
+ bfq_log(bfqd, "disconnect_groups beginning");
+ hlist_for_each_entry_safe(bfqg, pos, n, &bfqd->group_list, bfqd_node) {
+ hlist_del(&bfqg->bfqd_node);
+
+ __bfq_deactivate_entity(bfqg->my_entity, 0);
+
+ /*
+ * Don't remove from the group hash, just set an
+ * invalid key. No lookups can race with the
+ * assignment as bfqd is being destroyed; this
+ * implies also that new elements cannot be added
+ * to the list.
+ */
+ rcu_assign_pointer(bfqg->bfqd, NULL);
+
+ bfq_log(bfqd, "disconnect_groups: put async for group %p",
+ bfqg);
+ bfq_put_async_queues(bfqd, bfqg);
+ }
+}
+
+static inline void bfq_free_root_group(struct bfq_data *bfqd)
+{
+ struct bfqio_cgroup *bgrp = &bfqio_root_cgroup;
+ struct bfq_group *bfqg = bfqd->root_group;
+
+ bfq_put_async_queues(bfqd, bfqg);
+
+ spin_lock_irq(&bgrp->lock);
+ hlist_del_rcu(&bfqg->group_node);
+ spin_unlock_irq(&bgrp->lock);
+
+ /*
+ * No need to synchronize_rcu() here: since the device is gone
+ * there cannot be any read-side access to its root_group.
+ */
+ kfree(bfqg);
+}
+
+static struct bfq_group *bfq_alloc_root_group(struct bfq_data *bfqd, int node)
+{
+ struct bfq_group *bfqg;
+ struct bfqio_cgroup *bgrp;
+ int i;
+
+ bfqg = kzalloc_node(sizeof(*bfqg), GFP_KERNEL, node);
+ if (bfqg == NULL)
+ return NULL;
+
+ bfqg->entity.parent = NULL;
+ for (i = 0; i < BFQ_IOPRIO_CLASSES; i++)
+ bfqg->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT;
+
+ bgrp = &bfqio_root_cgroup;
+ spin_lock_irq(&bgrp->lock);
+ rcu_assign_pointer(bfqg->bfqd, bfqd);
+ hlist_add_head_rcu(&bfqg->group_node, &bgrp->group_data);
+ spin_unlock_irq(&bgrp->lock);
+
+ return bfqg;
+}
+
+#define SHOW_FUNCTION(__VAR) \
+static u64 bfqio_cgroup_##__VAR##_read(struct cgroup *cgroup, \
+ struct cftype *cftype) \
+{ \
+ struct bfqio_cgroup *bgrp; \
+ u64 ret; \
+ \
+ if (!cgroup_lock_live_group(cgroup)) \
+ return -ENODEV; \
+ \
+ bgrp = cgroup_to_bfqio(cgroup); \
+ spin_lock_irq(&bgrp->lock); \
+ ret = bgrp->__VAR; \
+ spin_unlock_irq(&bgrp->lock); \
+ \
+ cgroup_unlock(); \
+ \
+ return ret; \
+}
+
+SHOW_FUNCTION(weight);
+SHOW_FUNCTION(ioprio);
+SHOW_FUNCTION(ioprio_class);
+#undef SHOW_FUNCTION
+
+#define STORE_FUNCTION(__VAR, __MIN, __MAX) \
+static int bfqio_cgroup_##__VAR##_write(struct cgroup *cgroup, \
+ struct cftype *cftype, \
+ u64 val) \
+{ \
+ struct bfqio_cgroup *bgrp; \
+ struct bfq_group *bfqg; \
+ struct hlist_node *n; \
+ \
+ if (val < (__MIN) || val > (__MAX)) \
+ return -EINVAL; \
+ \
+ if (!cgroup_lock_live_group(cgroup)) \
+ return -ENODEV; \
+ \
+ bgrp = cgroup_to_bfqio(cgroup); \
+ \
+ spin_lock_irq(&bgrp->lock); \
+ bgrp->__VAR = (unsigned short)val; \
+ hlist_for_each_entry(bfqg, n, &bgrp->group_data, group_node) { \
+ /* \
+ * Setting the ioprio_changed flag of the entity \
+ * to 1 with new_##__VAR == ##__VAR would re-set \
+ * the value of the weight to its ioprio mapping. \
+ * Set the flag only if necessary. \
+ */ \
+ if ((unsigned short)val != bfqg->entity.new_##__VAR) { \
+ bfqg->entity.new_##__VAR = (unsigned short)val; \
+ /* \
+ * Make sure that the above new value has been \
+ * stored in bfqg->entity.new_##__VAR before \
+ * setting the ioprio_changed flag. In fact, \
+ * this flag may be read asynchronously (in \
+ * critical sections protected by a different \
+ * lock than that held here), and finding this \
+ * flag set may cause the execution of the code \
+ * for updating parameters whose value may \
+ * depend also on bfqg->entity.new_##__VAR (in \
+ * __bfq_entity_update_weight_prio). \
+ * This barrier makes sure that the new value \
+ * of bfqg->entity.new_##__VAR is correctly \
+ * seen in that code. \
+ */ \
+ smp_wmb(); \
+ bfqg->entity.ioprio_changed = 1; \
+ } \
+ } \
+ spin_unlock_irq(&bgrp->lock); \
+ \
+ cgroup_unlock(); \
+ \
+ return 0; \
+}
+
+STORE_FUNCTION(weight, BFQ_MIN_WEIGHT, BFQ_MAX_WEIGHT);
+STORE_FUNCTION(ioprio, 0, IOPRIO_BE_NR - 1);
+STORE_FUNCTION(ioprio_class, IOPRIO_CLASS_RT, IOPRIO_CLASS_IDLE);
+#undef STORE_FUNCTION
+
+static struct cftype bfqio_files[] = {
+ {
+ .name = "weight",
+ .read_u64 = bfqio_cgroup_weight_read,
+ .write_u64 = bfqio_cgroup_weight_write,
+ },
+ {
+ .name = "ioprio",
+ .read_u64 = bfqio_cgroup_ioprio_read,
+ .write_u64 = bfqio_cgroup_ioprio_write,
+ },
+ {
+ .name = "ioprio_class",
+ .read_u64 = bfqio_cgroup_ioprio_class_read,
+ .write_u64 = bfqio_cgroup_ioprio_class_write,
+ },
+};
+
+static int bfqio_populate(struct cgroup_subsys *subsys, struct cgroup *cgroup)
+{
+ return cgroup_add_files(cgroup, subsys, bfqio_files,
+ ARRAY_SIZE(bfqio_files));
+}
+
+static struct cgroup_subsys_state *bfqio_create(struct cgroup *cgroup)
+{
+ struct bfqio_cgroup *bgrp;
+
+ if (cgroup->parent != NULL) {
+ bgrp = kzalloc(sizeof(*bgrp), GFP_KERNEL);
+ if (bgrp == NULL)
+ return ERR_PTR(-ENOMEM);
+ } else
+ bgrp = &bfqio_root_cgroup;
+
+ spin_lock_init(&bgrp->lock);
+ INIT_HLIST_HEAD(&bgrp->group_data);
+ bgrp->ioprio = BFQ_DEFAULT_GRP_IOPRIO;
+ bgrp->ioprio_class = BFQ_DEFAULT_GRP_CLASS;
+
+ return &bgrp->css;
+}
+
+/*
+ * We cannot support shared io contexts, as we have no means to support
+ * two tasks with the same ioc in two different groups without major rework
+ * of the main bic/bfqq data structures. By now we allow a task to change
+ * its cgroup only if it's the only owner of its ioc; the drawback of this
+ * behavior is that a group containing a task that forked using CLONE_IO
+ * will not be destroyed until the tasks sharing the ioc die.
+ */
+static int bfqio_can_attach(struct cgroup *cgroup, struct cgroup_taskset *tset)
+{
+ struct task_struct *task;
+ struct io_context *ioc;
+ int ret = 0;
+
+ cgroup_taskset_for_each(task, cgroup, tset) {
+ /* task_lock() is needed to avoid races with exit_io_context() */
+ task_lock(task);
+ ioc = task->io_context;
+ if (ioc != NULL && atomic_read(&ioc->nr_tasks) > 1)
+ /*
+ * ioc == NULL means that the task is either too
+ * young or exiting: if it has still no ioc the
+ * ioc can't be shared, if the task is exiting the
+ * attach will fail anyway, no matter what we
+ * return here.
+ */
+ ret = -EINVAL;
+ task_unlock(task);
+ if (ret)
+ break;
+ }
+
+ return ret;
+}
+
+static void bfqio_attach(struct cgroup *cgroup, struct cgroup_taskset *tset)
+{
+ struct task_struct *task;
+ struct io_context *ioc;
+ struct io_cq *icq;
+ struct hlist_node *n;
+
+ /*
+ * IMPORTANT NOTE: The move of more than one process at a time to a
+ * new group has not yet been tested.
+ */
+ cgroup_taskset_for_each(task, cgroup, tset) {
+ ioc = get_task_io_context(task, GFP_ATOMIC, NUMA_NO_NODE);
+ if (ioc) {
+ /*
+ * Handle cgroup change here.
+ */
+ rcu_read_lock();
+ hlist_for_each_entry_rcu(icq, n, &ioc->icq_list, ioc_node)
+ if (!strncmp(
+ icq->q->elevator->type->elevator_name,
+ "bfq", ELV_NAME_MAX))
+ bfq_bic_change_cgroup(icq_to_bic(icq),
+ cgroup);
+ rcu_read_unlock();
+ put_io_context(ioc);
+ }
+ }
+}
+
+static void bfqio_destroy(struct cgroup *cgroup)
+{
+ struct bfqio_cgroup *bgrp = cgroup_to_bfqio(cgroup);
+ struct hlist_node *n, *tmp;
+ struct bfq_group *bfqg;
+
+ /*
+ * Since we are destroying the cgroup, there are no more tasks
+ * referencing it, and all the RCU grace periods that may have
+ * referenced it are ended (as the destruction of the parent
+ * cgroup is RCU-safe); bgrp->group_data will not be accessed by
+ * anything else and we don't need any synchronization.
+ */
+ hlist_for_each_entry_safe(bfqg, n, tmp, &bgrp->group_data, group_node)
+ bfq_destroy_group(bgrp, bfqg);
+
+ BUG_ON(!hlist_empty(&bgrp->group_data));
+
+ kfree(bgrp);
+}
+
+struct cgroup_subsys bfqio_subsys = {
+ .name = "bfqio",
+ .create = bfqio_create,
+ .can_attach = bfqio_can_attach,
+ .attach = bfqio_attach,
+ .destroy = bfqio_destroy,
+ .populate = bfqio_populate,
+ .subsys_id = bfqio_subsys_id,
+};
+#else
+static inline void bfq_init_entity(struct bfq_entity *entity,
+ struct bfq_group *bfqg)
+{
+ entity->weight = entity->new_weight;
+ entity->orig_weight = entity->new_weight;
+ entity->ioprio = entity->new_ioprio;
+ entity->ioprio_class = entity->new_ioprio_class;
+ entity->sched_data = &bfqg->sched_data;
+}
+
+static inline struct bfq_group *
+bfq_bic_update_cgroup(struct bfq_io_cq *bic)
+{
+ struct bfq_data *bfqd = bic_to_bfqd(bic);
+ return bfqd->root_group;
+}
+
+static inline void bfq_bfqq_move(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ struct bfq_entity *entity,
+ struct bfq_group *bfqg)
+{
+}
+
+static void bfq_end_wr_async(struct bfq_data *bfqd)
+{
+ bfq_end_wr_async_queues(bfqd, bfqd->root_group);
+}
+
+static inline void bfq_disconnect_groups(struct bfq_data *bfqd)
+{
+ bfq_put_async_queues(bfqd, bfqd->root_group);
+}
+
+static inline void bfq_free_root_group(struct bfq_data *bfqd)
+{
+ kfree(bfqd->root_group);
+}
+
+static struct bfq_group *bfq_alloc_root_group(struct bfq_data *bfqd, int node)
+{
+ struct bfq_group *bfqg;
+ int i;
+
+ bfqg = kmalloc_node(sizeof(*bfqg), GFP_KERNEL | __GFP_ZERO, node);
+ if (bfqg == NULL)
+ return NULL;
+
+ for (i = 0; i < BFQ_IOPRIO_CLASSES; i++)
+ bfqg->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT;
+
+ return bfqg;
+}
+#endif
diff --git a/block/bfq-ioc.c b/block/bfq-ioc.c
new file mode 100644
index 0000000..7f6b000
--- /dev/null
+++ b/block/bfq-ioc.c
@@ -0,0 +1,36 @@
+/*
+ * BFQ: I/O context handling.
+ *
+ * Based on ideas and code from CFQ:
+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
+ *
+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
+ * Paolo Valente <paolo.valente@unimore.it>
+ *
+ * Copyright (C) 2010 Paolo Valente <paolo.valente@unimore.it>
+ */
+
+/**
+ * icq_to_bic - convert iocontext queue structure to bfq_io_cq.
+ * @icq: the iocontext queue.
+ */
+static inline struct bfq_io_cq *icq_to_bic(struct io_cq *icq)
+{
+ /* bic->icq is the first member, %NULL will convert to %NULL */
+ return container_of(icq, struct bfq_io_cq, icq);
+}
+
+/**
+ * bfq_bic_lookup - search into @ioc a bic associated to @bfqd.
+ * @bfqd: the lookup key.
+ * @ioc: the io_context of the process doing I/O.
+ *
+ * Queue lock must be held.
+ */
+static inline struct bfq_io_cq *bfq_bic_lookup(struct bfq_data *bfqd,
+ struct io_context *ioc)
+{
+ if (ioc)
+ return icq_to_bic(ioc_lookup_icq(ioc, bfqd->queue));
+ return NULL;
+}
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
new file mode 100644
index 0000000..152992b
--- /dev/null
+++ b/block/bfq-iosched.c
@@ -0,0 +1,4208 @@
+/*
+ * Budget Fair Queueing (BFQ) disk scheduler.
+ *
+ * Based on ideas and code from CFQ:
+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
+ *
+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
+ * Paolo Valente <paolo.valente@unimore.it>
+ *
+ * Copyright (C) 2010 Paolo Valente <paolo.valente@unimore.it>
+ *
+ * Licensed under the GPL-2 as detailed in the accompanying COPYING.BFQ
+ * file.
+ *
+ * BFQ is a proportional-share storage-I/O scheduling algorithm based on
+ * the slice-by-slice service scheme of CFQ. But BFQ assigns budgets,
+ * measured in number of sectors, to processes instead of time slices. The
+ * device is not granted to the in-service process for a given time slice,
+ * but until it has exhausted its assigned budget. This change from the time
+ * to the service domain allows BFQ to distribute the device throughput
+ * among processes as desired, without any distortion due to ZBR, workload
+ * fluctuations or other factors. BFQ uses an ad hoc internal scheduler,
+ * called B-WF2Q+, to schedule processes according to their budgets. More
+ * precisely, BFQ schedules queues associated to processes. Thanks to the
+ * accurate policy of B-WF2Q+, BFQ can afford to assign high budgets to
+ * I/O-bound processes issuing sequential requests (to boost the
+ * throughput), and yet guarantee a low latency to interactive and soft
+ * real-time applications.
+ *
+ * BFQ is described in [1], where also a reference to the initial, more
+ * theoretical paper on BFQ can be found. The interested reader can find
+ * in the latter paper full details on the main algorithm, as well as
+ * formulas of the guarantees and formal proofs of all the properties.
+ * With respect to the version of BFQ presented in these papers, this
+ * implementation adds a few more heuristics, such as the one that
+ * guarantees a low latency to soft real-time applications, and a
+ * hierarchical extension based on H-WF2Q+.
+ *
+ * B-WF2Q+ is based on WF2Q+, that is described in [2], together with
+ * H-WF2Q+, while the augmented tree used to implement B-WF2Q+ with O(log N)
+ * complexity derives from the one introduced with EEVDF in [3].
+ *
+ * [1] P. Valente and M. Andreolini, ``Improving Application Responsiveness
+ * with the BFQ Disk I/O Scheduler'',
+ * Proceedings of the 5th Annual International Systems and Storage
+ * Conference (SYSTOR '12), June 2012.
+ *
+ * http://algogroup.unimo.it/people/paolo/disk_sched/bf1-v1-suite-results.pdf
+ *
+ * [2] Jon C.R. Bennett and H. Zhang, ``Hierarchical Packet Fair Queueing
+ * Algorithms,'' IEEE/ACM Transactions on Networking, 5(5):675-689,
+ * Oct 1997.
+ *
+ * http://www.cs.cmu.edu/~hzhang/papers/TON-97-Oct.ps.gz
+ *
+ * [3] I. Stoica and H. Abdel-Wahab, ``Earliest Eligible Virtual Deadline
+ * First: A Flexible and Accurate Mechanism for Proportional Share
+ * Resource Allocation,'' technical report.
+ *
+ * http://www.cs.berkeley.edu/~istoica/papers/eevdf-tr-95.pdf
+ */
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/blkdev.h>
+#include <linux/cgroup.h>
+#include <linux/elevator.h>
+#include <linux/jiffies.h>
+#include <linux/rbtree.h>
+#include <linux/ioprio.h>
+#include "bfq.h"
+#include "blk.h"
+
+/* Max number of dispatches in one round of service. */
+static const int bfq_quantum = 4;
+
+/* Expiration time of sync (0) and async (1) requests, in jiffies. */
+static const int bfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
+
+/* Maximum backwards seek, in KiB. */
+static const int bfq_back_max = 16 * 1024;
+
+/* Penalty of a backwards seek, in number of sectors. */
+static const int bfq_back_penalty = 2;
+
+/* Idling period duration, in jiffies. */
+static int bfq_slice_idle = HZ / 125;
+
+/* Default maximum budget values, in sectors and number of requests. */
+static const int bfq_default_max_budget = 16 * 1024;
+static const int bfq_max_budget_async_rq = 4;
+
+/*
+ * Async to sync throughput distribution is controlled as follows:
+ * when an async request is served, the entity is charged the number
+ * of sectors of the request, multiplied by the factor below
+ */
+static const int bfq_async_charge_factor = 10;
+
+/* Default timeout values, in jiffies, approximating CFQ defaults. */
+static const int bfq_timeout_sync = HZ / 8;
+static int bfq_timeout_async = HZ / 25;
+
+struct kmem_cache *bfq_pool;
+
+/* Below this threshold (in ms), we consider thinktime immediate. */
+#define BFQ_MIN_TT 2
+
+/* hw_tag detection: parallel requests threshold and min samples needed. */
+#define BFQ_HW_QUEUE_THRESHOLD 4
+#define BFQ_HW_QUEUE_SAMPLES 32
+
+#define BFQQ_SEEK_THR (sector_t)(8 * 1024)
+#define BFQQ_SEEKY(bfqq) ((bfqq)->seek_mean > BFQQ_SEEK_THR)
+
+/* Min samples used for peak rate estimation (for autotuning). */
+#define BFQ_PEAK_RATE_SAMPLES 32
+
+/* Shift used for peak rate fixed precision calculations. */
+#define BFQ_RATE_SHIFT 16
+
+/*
+ * By default, BFQ computes the duration of the weight raising for
+ * interactive applications automatically, using the following formula:
+ * duration = (R / r) * T, where r is the peak rate of the device, and
+ * R and T are two reference parameters.
+ * In particular, R is the peak rate of the reference device (see below),
+ * and T is a reference time: given the systems that are likely to be
+ * installed on the reference device according to its speed class, T is
+ * about the maximum time needed, under BFQ and while reading two files in
+ * parallel, to load typical large applications on these systems.
+ * In practice, the slower/faster the device at hand is, the more/less it
+ * takes to load applications with respect to the reference device.
+ * Accordingly, the longer/shorter BFQ grants weight raising to interactive
+ * applications.
+ *
+ * BFQ uses four different reference pairs (R, T), depending on:
+ * . whether the device is rotational or non-rotational;
+ * . whether the device is slow, such as old or portable HDDs, as well as
+ * SD cards, or fast, such as newer HDDs and SSDs.
+ *
+ * The device's speed class is dynamically (re)detected in
+ * bfq_update_peak_rate() every time the estimated peak rate is updated.
+ *
+ * In the following definitions, R_slow[0]/R_fast[0] and T_slow[0]/T_fast[0]
+ * are the reference values for a slow/fast rotational device, whereas
+ * R_slow[1]/R_fast[1] and T_slow[1]/T_fast[1] are the reference values for
+ * a slow/fast non-rotational device. Finally, device_speed_thresh are the
+ * thresholds used to switch between speed classes.
+ * Both the reference peak rates and the thresholds are measured in
+ * sectors/usec, left-shifted by BFQ_RATE_SHIFT.
+ */
+static int R_slow[2] = {1536, 10752};
+static int R_fast[2] = {17415, 34791};
+/*
+ * To improve readability, a conversion function is used to initialize the
+ * following arrays, which entails that they can be initialized only in a
+ * function.
+ */
+static int T_slow[2];
+static int T_fast[2];
+static int device_speed_thresh[2];
+
+#define BFQ_SERVICE_TREE_INIT ((struct bfq_service_tree) \
+ { RB_ROOT, RB_ROOT, NULL, NULL, 0, 0 })
+
+#define RQ_BIC(rq) ((struct bfq_io_cq *) (rq)->elv.priv[0])
+#define RQ_BFQQ(rq) ((rq)->elv.priv[1])
+
+static inline void bfq_schedule_dispatch(struct bfq_data *bfqd);
+
+#include "bfq-ioc.c"
+#include "bfq-sched.c"
+#include "bfq-cgroup.c"
+
+#define bfq_class_idle(bfqq) ((bfqq)->entity.ioprio_class ==\
+ IOPRIO_CLASS_IDLE)
+#define bfq_class_rt(bfqq) ((bfqq)->entity.ioprio_class ==\
+ IOPRIO_CLASS_RT)
+
+#define bfq_sample_valid(samples) ((samples) > 80)
+
+/*
+ * We regard a request as SYNC, if either it's a read or has the SYNC bit
+ * set (in which case it could also be a direct WRITE).
+ */
+static inline int bfq_bio_sync(struct bio *bio)
+{
+ if (bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC))
+ return 1;
+
+ return 0;
+}
+
+/*
+ * Scheduler run of queue, if there are requests pending and no one in the
+ * driver that will restart queueing.
+ */
+static inline void bfq_schedule_dispatch(struct bfq_data *bfqd)
+{
+ if (bfqd->queued != 0) {
+ bfq_log(bfqd, "schedule dispatch");
+ kblockd_schedule_work(bfqd->queue, &bfqd->unplug_work);
+ }
+}
+
+/*
+ * Lifted from AS - choose which of rq1 and rq2 that is best served now.
+ * We choose the request that is closesr to the head right now. Distance
+ * behind the head is penalized and only allowed to a certain extent.
+ */
+static struct request *bfq_choose_req(struct bfq_data *bfqd,
+ struct request *rq1,
+ struct request *rq2,
+ sector_t last)
+{
+ sector_t s1, s2, d1 = 0, d2 = 0;
+ unsigned long back_max;
+#define BFQ_RQ1_WRAP 0x01 /* request 1 wraps */
+#define BFQ_RQ2_WRAP 0x02 /* request 2 wraps */
+ unsigned wrap = 0; /* bit mask: requests behind the disk head? */
+
+ if (rq1 == NULL || rq1 == rq2)
+ return rq2;
+ if (rq2 == NULL)
+ return rq1;
+
+ if (rq_is_sync(rq1) && !rq_is_sync(rq2))
+ return rq1;
+ else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
+ return rq2;
+ if ((rq1->cmd_flags & REQ_META) && !(rq2->cmd_flags & REQ_META))
+ return rq1;
+ else if ((rq2->cmd_flags & REQ_META) && !(rq1->cmd_flags & REQ_META))
+ return rq2;
+
+ s1 = blk_rq_pos(rq1);
+ s2 = blk_rq_pos(rq2);
+
+ /*
+ * By definition, 1KiB is 2 sectors.
+ */
+ back_max = bfqd->bfq_back_max * 2;
+
+ /*
+ * Strict one way elevator _except_ in the case where we allow
+ * short backward seeks which are biased as twice the cost of a
+ * similar forward seek.
+ */
+ if (s1 >= last)
+ d1 = s1 - last;
+ else if (s1 + back_max >= last)
+ d1 = (last - s1) * bfqd->bfq_back_penalty;
+ else
+ wrap |= BFQ_RQ1_WRAP;
+
+ if (s2 >= last)
+ d2 = s2 - last;
+ else if (s2 + back_max >= last)
+ d2 = (last - s2) * bfqd->bfq_back_penalty;
+ else
+ wrap |= BFQ_RQ2_WRAP;
+
+ /* Found required data */
+
+ /*
+ * By doing switch() on the bit mask "wrap" we avoid having to
+ * check two variables for all permutations: --> faster!
+ */
+ switch (wrap) {
+ case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
+ if (d1 < d2)
+ return rq1;
+ else if (d2 < d1)
+ return rq2;
+ else {
+ if (s1 >= s2)
+ return rq1;
+ else
+ return rq2;
+ }
+
+ case BFQ_RQ2_WRAP:
+ return rq1;
+ case BFQ_RQ1_WRAP:
+ return rq2;
+ case (BFQ_RQ1_WRAP|BFQ_RQ2_WRAP): /* both rqs wrapped */
+ default:
+ /*
+ * Since both rqs are wrapped,
+ * start with the one that's further behind head
+ * (--> only *one* back seek required),
+ * since back seek takes more time than forward.
+ */
+ if (s1 <= s2)
+ return rq1;
+ else
+ return rq2;
+ }
+}
+
+static struct bfq_queue *
+bfq_rq_pos_tree_lookup(struct bfq_data *bfqd, struct rb_root *root,
+ sector_t sector, struct rb_node **ret_parent,
+ struct rb_node ***rb_link)
+{
+ struct rb_node **p, *parent;
+ struct bfq_queue *bfqq = NULL;
+
+ parent = NULL;
+ p = &root->rb_node;
+ while (*p) {
+ struct rb_node **n;
+
+ parent = *p;
+ bfqq = rb_entry(parent, struct bfq_queue, pos_node);
+
+ /*
+ * Sort strictly based on sector. Smallest to the left,
+ * largest to the right.
+ */
+ if (sector > blk_rq_pos(bfqq->next_rq))
+ n = &(*p)->rb_right;
+ else if (sector < blk_rq_pos(bfqq->next_rq))
+ n = &(*p)->rb_left;
+ else
+ break;
+ p = n;
+ bfqq = NULL;
+ }
+
+ *ret_parent = parent;
+ if (rb_link)
+ *rb_link = p;
+
+ bfq_log(bfqd, "rq_pos_tree_lookup %llu: returning %d",
+ (long long unsigned)sector,
+ bfqq != NULL ? bfqq->pid : 0);
+
+ return bfqq;
+}
+
+static void bfq_rq_pos_tree_add(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+{
+ struct rb_node **p, *parent;
+ struct bfq_queue *__bfqq;
+
+ if (bfqq->pos_root != NULL) {
+ rb_erase(&bfqq->pos_node, bfqq->pos_root);
+ bfqq->pos_root = NULL;
+ }
+
+ if (bfq_class_idle(bfqq))
+ return;
+ if (!bfqq->next_rq)
+ return;
+
+ bfqq->pos_root = &bfqd->rq_pos_tree;
+ __bfqq = bfq_rq_pos_tree_lookup(bfqd, bfqq->pos_root,
+ blk_rq_pos(bfqq->next_rq), &parent, &p);
+ if (__bfqq == NULL) {
+ rb_link_node(&bfqq->pos_node, parent, p);
+ rb_insert_color(&bfqq->pos_node, bfqq->pos_root);
+ } else
+ bfqq->pos_root = NULL;
+}
+
+/*
+ * Tell whether there are active queues or groups with differentiated weights.
+ */
+static inline bool bfq_differentiated_weights(struct bfq_data *bfqd)
+{
+ BUG_ON(!bfqd->hw_tag);
+ /*
+ * For weights to differ, at least one of the trees must contain
+ * at least two nodes.
+ */
+ return (!RB_EMPTY_ROOT(&bfqd->queue_weights_tree) &&
+ (bfqd->queue_weights_tree.rb_node->rb_left ||
+ bfqd->queue_weights_tree.rb_node->rb_right)
+#ifdef CONFIG_CGROUP_BFQIO
+ ) ||
+ (!RB_EMPTY_ROOT(&bfqd->group_weights_tree) &&
+ (bfqd->group_weights_tree.rb_node->rb_left ||
+ bfqd->group_weights_tree.rb_node->rb_right)
+#endif
+ );
+}
+
+/*
+ * If the weight-counter tree passed as input contains no counter for
+ * the weight of the input entity, then add that counter; otherwise just
+ * increment the existing counter.
+ *
+ * Note that weight-counter trees contain few nodes in mostly symmetric
+ * scenarios. For example, if all queues have the same weight, then the
+ * weight-counter tree for the queues may contain at most one node.
+ * This holds even if low_latency is on, because weight-raised queues
+ * are not inserted in the tree.
+ * In most scenarios, the rate at which nodes are created/destroyed
+ * should be low too.
+ */
+static void bfq_weights_tree_add(struct bfq_data *bfqd,
+ struct bfq_entity *entity,
+ struct rb_root *root)
+{
+ struct rb_node **new = &(root->rb_node), *parent = NULL;
+
+ /*
+ * Do not insert if:
+ * - the device does not support queueing;
+ * - the entity is already associated with a counter, which happens if:
+ * 1) the entity is associated with a queue, 2) a request arrival
+ * has caused the queue to become both non-weight-raised, and hence
+ * change its weight, and backlogged; in this respect, each
+ * of the two events causes an invocation of this function,
+ * 3) this is the invocation of this function caused by the second
+ * event. This second invocation is actually useless, and we handle
+ * this fact by exiting immediately. More efficient or clearer
+ * solutions might possibly be adopted.
+ */
+ if (!bfqd->hw_tag || entity->weight_counter)
+ return;
+
+ while (*new) {
+ struct bfq_weight_counter *__counter = container_of(*new,
+ struct bfq_weight_counter,
+ weights_node);
+ parent = *new;
+
+ if (entity->weight == __counter->weight) {
+ entity->weight_counter = __counter;
+ goto inc_counter;
+ }
+ if (entity->weight < __counter->weight)
+ new = &((*new)->rb_left);
+ else
+ new = &((*new)->rb_right);
+ }
+
+ entity->weight_counter = kzalloc(sizeof(struct bfq_weight_counter),
+ GFP_ATOMIC);
+ entity->weight_counter->weight = entity->weight;
+ rb_link_node(&entity->weight_counter->weights_node, parent, new);
+ rb_insert_color(&entity->weight_counter->weights_node, root);
+
+inc_counter:
+ entity->weight_counter->num_active++;
+}
+
+/*
+ * Decrement the weight counter associated with the entity, and, if the
+ * counter reaches 0, remove the counter from the tree.
+ * See the comments to the function bfq_weights_tree_add() for considerations
+ * about overhead.
+ */
+static void bfq_weights_tree_remove(struct bfq_data *bfqd,
+ struct bfq_entity *entity,
+ struct rb_root *root)
+{
+ /*
+ * Check whether the entity is actually associated with a counter.
+ * In fact, the device may not be considered NCQ-capable for a while,
+ * which implies that no insertion in the weight trees is performed,
+ * after which the device may start to be deemed NCQ-capable, and hence
+ * this function may start to be invoked. This may cause the function
+ * to be invoked for entities that are not associated with any counter.
+ */
+ if (!entity->weight_counter)
+ return;
+
+ BUG_ON(RB_EMPTY_ROOT(root));
+ BUG_ON(entity->weight_counter->weight != entity->weight);
+
+ BUG_ON(!entity->weight_counter->num_active);
+ entity->weight_counter->num_active--;
+ if (entity->weight_counter->num_active > 0)
+ goto reset_entity_pointer;
+
+ rb_erase(&entity->weight_counter->weights_node, root);
+ kfree(entity->weight_counter);
+
+reset_entity_pointer:
+ entity->weight_counter = NULL;
+}
+
+static struct request *bfq_find_next_rq(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ struct request *last)
+{
+ struct rb_node *rbnext = rb_next(&last->rb_node);
+ struct rb_node *rbprev = rb_prev(&last->rb_node);
+ struct request *next = NULL, *prev = NULL;
+
+ BUG_ON(RB_EMPTY_NODE(&last->rb_node));
+
+ if (rbprev != NULL)
+ prev = rb_entry_rq(rbprev);
+
+ if (rbnext != NULL)
+ next = rb_entry_rq(rbnext);
+ else {
+ rbnext = rb_first(&bfqq->sort_list);
+ if (rbnext && rbnext != &last->rb_node)
+ next = rb_entry_rq(rbnext);
+ }
+
+ return bfq_choose_req(bfqd, next, prev, blk_rq_pos(last));
+}
+
+/* see the definition of bfq_async_charge_factor for details */
+static inline unsigned long bfq_serv_to_charge(struct request *rq,
+ struct bfq_queue *bfqq)
+{
+ return blk_rq_sectors(rq) *
+ (1 + ((!bfq_bfqq_sync(bfqq)) * (bfqq->wr_coeff == 1) *
+ bfq_async_charge_factor));
+}
+
+/**
+ * bfq_updated_next_req - update the queue after a new next_rq selection.
+ * @bfqd: the device data the queue belongs to.
+ * @bfqq: the queue to update.
+ *
+ * If the first request of a queue changes we make sure that the queue
+ * has enough budget to serve at least its first request (if the
+ * request has grown). We do this because if the queue has not enough
+ * budget for its first request, it has to go through two dispatch
+ * rounds to actually get it dispatched.
+ */
+static void bfq_updated_next_req(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq)
+{
+ struct bfq_entity *entity = &bfqq->entity;
+ struct bfq_service_tree *st = bfq_entity_service_tree(entity);
+ struct request *next_rq = bfqq->next_rq;
+ unsigned long new_budget;
+
+ if (next_rq == NULL)
+ return;
+
+ if (bfqq == bfqd->in_service_queue)
+ /*
+ * In order not to break guarantees, budgets cannot be
+ * changed after an entity has been selected.
+ */
+ return;
+
+ BUG_ON(entity->tree != &st->active);
+ BUG_ON(entity == entity->sched_data->in_service_entity);
+
+ new_budget = max_t(unsigned long, bfqq->max_budget,
+ bfq_serv_to_charge(next_rq, bfqq));
+ if (entity->budget != new_budget) {
+ entity->budget = new_budget;
+ bfq_log_bfqq(bfqd, bfqq, "updated next rq: new budget %lu",
+ new_budget);
+ bfq_activate_bfqq(bfqd, bfqq);
+ }
+}
+
+static inline unsigned int bfq_wr_duration(struct bfq_data *bfqd)
+{
+ u64 dur;
+
+ if (bfqd->bfq_wr_max_time > 0)
+ return bfqd->bfq_wr_max_time;
+
+ dur = bfqd->RT_prod;
+ do_div(dur, bfqd->peak_rate);
+
+ return dur;
+}
+
+static inline unsigned
+bfq_bfqq_cooperations(struct bfq_queue *bfqq)
+{
+ return bfqq->bic ? bfqq->bic->cooperations : 0;
+}
+
+static inline void
+bfq_bfqq_resume_state(struct bfq_queue *bfqq, struct bfq_io_cq *bic)
+{
+ if (bic->saved_idle_window)
+ bfq_mark_bfqq_idle_window(bfqq);
+ else
+ bfq_clear_bfqq_idle_window(bfqq);
+ if (bic->saved_IO_bound)
+ bfq_mark_bfqq_IO_bound(bfqq);
+ else
+ bfq_clear_bfqq_IO_bound(bfqq);
+ /* Assuming that the flag in_large_burst is already correctly set */
+ if (bic->wr_time_left && bfqq->bfqd->low_latency &&
+ !bfq_bfqq_in_large_burst(bfqq) &&
+ bic->cooperations < bfqq->bfqd->bfq_coop_thresh) {
+ /*
+ * Start a weight raising period with the duration given by
+ * the raising_time_left snapshot.
+ */
+ if (bfq_bfqq_busy(bfqq))
+ bfqq->bfqd->wr_busy_queues++;
+ bfqq->wr_coeff = bfqq->bfqd->bfq_wr_coeff;
+ bfqq->wr_cur_max_time = bic->wr_time_left;
+ bfqq->last_wr_start_finish = jiffies;
+ bfqq->entity.ioprio_changed = 1;
+ }
+ /*
+ * Clear wr_time_left to prevent bfq_bfqq_save_state() from
+ * getting confused about the queue's need of a weight-raising
+ * period.
+ */
+ bic->wr_time_left = 0;
+}
+
+/* Must be called with the queue_lock held. */
+static int bfqq_process_refs(struct bfq_queue *bfqq)
+{
+ int process_refs, io_refs;
+
+ io_refs = bfqq->allocated[READ] + bfqq->allocated[WRITE];
+ process_refs = atomic_read(&bfqq->ref) - io_refs - bfqq->entity.on_st;
+ BUG_ON(process_refs < 0);
+ return process_refs;
+}
+
+/* Empty burst list and add just bfqq (see comments to bfq_handle_burst) */
+static inline void bfq_reset_burst_list(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq)
+{
+ struct bfq_queue *item;
+ struct hlist_node *pos, *n;
+
+ hlist_for_each_entry_safe(item, pos, n,
+ &bfqd->burst_list, burst_list_node)
+ hlist_del_init(&item->burst_list_node);
+ hlist_add_head(&bfqq->burst_list_node, &bfqd->burst_list);
+ bfqd->burst_size = 1;
+}
+
+/* Add bfqq to the list of queues in current burst (see bfq_handle_burst) */
+static void bfq_add_to_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+{
+ /* Increment burst size to take into account also bfqq */
+ bfqd->burst_size++;
+
+ if (bfqd->burst_size == bfqd->bfq_large_burst_thresh) {
+ struct bfq_queue *pos, *bfqq_item;
+ struct hlist_node *p, *n;
+
+ /*
+ * Enough queues have been activated shortly after each
+ * other to consider this burst as large.
+ */
+ bfqd->large_burst = true;
+
+ /*
+ * We can now mark all queues in the burst list as
+ * belonging to a large burst.
+ */
+ hlist_for_each_entry(bfqq_item, n, &bfqd->burst_list,
+ burst_list_node)
+ bfq_mark_bfqq_in_large_burst(bfqq_item);
+ bfq_mark_bfqq_in_large_burst(bfqq);
+
+ /*
+ * From now on, and until the current burst finishes, any
+ * new queue being activated shortly after the last queue
+ * was inserted in the burst can be immediately marked as
+ * belonging to a large burst. So the burst list is not
+ * needed any more. Remove it.
+ */
+ hlist_for_each_entry_safe(pos, p, n, &bfqd->burst_list,
+ burst_list_node)
+ hlist_del_init(&pos->burst_list_node);
+ } else /* burst not yet large: add bfqq to the burst list */
+ hlist_add_head(&bfqq->burst_list_node, &bfqd->burst_list);
+}
+
+/*
+ * If many queues happen to become active shortly after each other, then,
+ * to help the processes associated to these queues get their job done as
+ * soon as possible, it is usually better to not grant either weight-raising
+ * or device idling to these queues. In this comment we describe, firstly,
+ * the reasons why this fact holds, and, secondly, the next function, which
+ * implements the main steps needed to properly mark these queues so that
+ * they can then be treated in a different way.
+ *
+ * As for the terminology, we say that a queue becomes active, i.e.,
+ * switches from idle to backlogged, either when it is created (as a
+ * consequence of the arrival of an I/O request), or, if already existing,
+ * when a new request for the queue arrives while the queue is idle.
+ * Bursts of activations, i.e., activations of different queues occurring
+ * shortly after each other, are typically caused by services or applications
+ * that spawn or reactivate many parallel threads/processes. Examples are
+ * systemd during boot or git grep.
+ *
+ * These services or applications benefit mostly from a high throughput:
+ * the quicker the requests of the activated queues are cumulatively served,
+ * the sooner the target job of these queues gets completed. As a consequence,
+ * weight-raising any of these queues, which also implies idling the device
+ * for it, is almost always counterproductive: in most cases it just lowers
+ * throughput.
+ *
+ * On the other hand, a burst of activations may be also caused by the start
+ * of an application that does not consist in a lot of parallel I/O-bound
+ * threads. In fact, with a complex application, the burst may be just a
+ * consequence of the fact that several processes need to be executed to
+ * start-up the application. To start an application as quickly as possible,
+ * the best thing to do is to privilege the I/O related to the application
+ * with respect to all other I/O. Therefore, the best strategy to start as
+ * quickly as possible an application that causes a burst of activations is
+ * to weight-raise all the queues activated during the burst. This is the
+ * exact opposite of the best strategy for the other type of bursts.
+ *
+ * In the end, to take the best action for each of the two cases, the two
+ * types of bursts need to be distinguished. Fortunately, this seems
+ * relatively easy to do, by looking at the sizes of the bursts. In
+ * particular, we found a threshold such that bursts with a larger size
+ * than that threshold are apparently caused only by services or commands
+ * such as systemd or git grep. For brevity, hereafter we call just 'large'
+ * these bursts. BFQ *does not* weight-raise queues whose activations occur
+ * in a large burst. In addition, for each of these queues BFQ performs or
+ * does not perform idling depending on which choice boosts the throughput
+ * most. The exact choice depends on the device and request pattern at
+ * hand.
+ *
+ * Turning back to the next function, it implements all the steps needed
+ * to detect the occurrence of a large burst and to properly mark all the
+ * queues belonging to it (so that they can then be treated in a different
+ * way). This goal is achieved by maintaining a special "burst list" that
+ * holds, temporarily, the queues that belong to the burst in progress. The
+ * list is then used to mark these queues as belonging to a large burst if
+ * the burst does become large. The main steps are the following.
+ *
+ * . when the very first queue is activated, the queue is inserted into the
+ * list (as it could be the first queue in a possible burst)
+ *
+ * . if the current burst has not yet become large, and a queue Q that does
+ * not yet belong to the burst is activated shortly after the last time
+ * at which a new queue entered the burst list, then the function appends
+ * Q to the burst list
+ *
+ * . if, as a consequence of the previous step, the burst size reaches
+ * the large-burst threshold, then
+ *
+ * . all the queues in the burst list are marked as belonging to a
+ * large burst
+ *
+ * . the burst list is deleted; in fact, the burst list already served
+ * its purpose (keeping temporarily track of the queues in a burst,
+ * so as to be able to mark them as belonging to a large burst in the
+ * previous sub-step), and now is not needed any more
+ *
+ * . the device enters a large-burst mode
+ *
+ * . if a queue Q that does not belong to the burst is activated while
+ * the device is in large-burst mode and shortly after the last time
+ * at which a queue either entered the burst list or was marked as
+ * belonging to the current large burst, then Q is immediately marked
+ * as belonging to a large burst.
+ *
+ * . if a queue Q that does not belong to the burst is activated a while
+ * later, i.e., not shortly after, than the last time at which a queue
+ * either entered the burst list or was marked as belonging to the
+ * current large burst, then the current burst is deemed as finished and:
+ *
+ * . the large-burst mode is reset if set
+ *
+ * . the burst list is emptied
+ *
+ * . Q is inserted in the burst list, as Q may be the first queue
+ * in a possible new burst (then the burst list contains just Q
+ * after this step).
+ */
+static void bfq_handle_burst(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ bool idle_for_long_time)
+{
+ /*
+ * If bfqq happened to be activated in a burst, but has been idle
+ * for at least as long as an interactive queue, then we assume
+ * that, in the overall I/O initiated in the burst, the I/O
+ * associated to bfqq is finished. So bfqq does not need to be
+ * treated as a queue belonging to a burst anymore. Accordingly,
+ * we reset bfqq's in_large_burst flag if set, and remove bfqq
+ * from the burst list if it's there. We do not decrement instead
+ * burst_size, because the fact that bfqq does not need to belong
+ * to the burst list any more does not invalidate the fact that
+ * bfqq may have been activated during the current burst.
+ */
+ if (idle_for_long_time) {
+ hlist_del_init(&bfqq->burst_list_node);
+ bfq_clear_bfqq_in_large_burst(bfqq);
+ }
+
+ /*
+ * If bfqq is already in the burst list or is part of a large
+ * burst, then there is nothing else to do.
+ */
+ if (!hlist_unhashed(&bfqq->burst_list_node) ||
+ bfq_bfqq_in_large_burst(bfqq))
+ return;
+
+ /*
+ * If bfqq's activation happens late enough, then the current
+ * burst is finished, and related data structures must be reset.
+ *
+ * In this respect, consider the special case where bfqq is the very
+ * first queue being activated. In this case, last_ins_in_burst is
+ * not yet significant when we get here. But it is easy to verify
+ * that, whether or not the following condition is true, bfqq will
+ * end up being inserted into the burst list. In particular the
+ * list will happen to contain only bfqq. And this is exactly what
+ * has to happen, as bfqq may be the first queue in a possible
+ * burst.
+ */
+ if (time_is_before_jiffies(bfqd->last_ins_in_burst +
+ bfqd->bfq_burst_interval)) {
+ bfqd->large_burst = false;
+ bfq_reset_burst_list(bfqd, bfqq);
+ return;
+ }
+
+ /*
+ * If we get here, then bfqq is being activated shortly after the
+ * last queue. So, if the current burst is also large, we can mark
+ * bfqq as belonging to this large burst immediately.
+ */
+ if (bfqd->large_burst) {
+ bfq_mark_bfqq_in_large_burst(bfqq);
+ return;
+ }
+
+ /*
+ * If we get here, then a large-burst state has not yet been
+ * reached, but bfqq is being activated shortly after the last
+ * queue. Then we add bfqq to the burst.
+ */
+ bfq_add_to_burst(bfqd, bfqq);
+}
+
+static void bfq_add_request(struct request *rq)
+{
+ struct bfq_queue *bfqq = RQ_BFQQ(rq);
+ struct bfq_entity *entity = &bfqq->entity;
+ struct bfq_data *bfqd = bfqq->bfqd;
+ struct request *next_rq, *prev;
+ unsigned long old_wr_coeff = bfqq->wr_coeff;
+ bool interactive = false;
+
+ bfq_log_bfqq(bfqd, bfqq, "add_request %d", rq_is_sync(rq));
+ bfqq->queued[rq_is_sync(rq)]++;
+ bfqd->queued++;
+
+ elv_rb_add(&bfqq->sort_list, rq);
+
+ /*
+ * Check if this request is a better next-serve candidate.
+ */
+ prev = bfqq->next_rq;
+ next_rq = bfq_choose_req(bfqd, bfqq->next_rq, rq, bfqd->last_position);
+ BUG_ON(next_rq == NULL);
+ bfqq->next_rq = next_rq;
+
+ /*
+ * Adjust priority tree position, if next_rq changes.
+ */
+ if (prev != bfqq->next_rq)
+ bfq_rq_pos_tree_add(bfqd, bfqq);
+
+ if (!bfq_bfqq_busy(bfqq)) {
+ bool soft_rt, coop_or_in_burst,
+ idle_for_long_time = time_is_before_jiffies(
+ bfqq->budget_timeout +
+ bfqd->bfq_wr_min_idle_time);
+
+ if (bfq_bfqq_sync(bfqq)) {
+ bool already_in_burst =
+ !hlist_unhashed(&bfqq->burst_list_node) ||
+ bfq_bfqq_in_large_burst(bfqq);
+ bfq_handle_burst(bfqd, bfqq, idle_for_long_time);
+ /*
+ * If bfqq was not already in the current burst,
+ * then, at this point, bfqq either has been
+ * added to the current burst or has caused the
+ * current burst to terminate. In particular, in
+ * the second case, bfqq has become the first
+ * queue in a possible new burst.
+ * In both cases last_ins_in_burst needs to be
+ * moved forward.
+ */
+ if (!already_in_burst)
+ bfqd->last_ins_in_burst = jiffies;
+ }
+
+ coop_or_in_burst = bfq_bfqq_in_large_burst(bfqq) ||
+ bfq_bfqq_cooperations(bfqq) >= bfqd->bfq_coop_thresh;
+ soft_rt = bfqd->bfq_wr_max_softrt_rate > 0 &&
+ !coop_or_in_burst &&
+ time_is_before_jiffies(bfqq->soft_rt_next_start);
+ interactive = !coop_or_in_burst && idle_for_long_time;
+ entity->budget = max_t(unsigned long, bfqq->max_budget,
+ bfq_serv_to_charge(next_rq, bfqq));
+
+ if (!bfq_bfqq_IO_bound(bfqq)) {
+ if (time_before(jiffies,
+ RQ_BIC(rq)->ttime.last_end_request +
+ bfqd->bfq_slice_idle)) {
+ bfqq->requests_within_timer++;
+ if (bfqq->requests_within_timer >=
+ bfqd->bfq_requests_within_timer)
+ bfq_mark_bfqq_IO_bound(bfqq);
+ } else
+ bfqq->requests_within_timer = 0;
+ }
+
+ if (!bfqd->low_latency)
+ goto add_bfqq_busy;
+
+ if (bfq_bfqq_just_split(bfqq))
+ goto set_ioprio_changed;
+
+ /*
+ * If the queue:
+ * - is not being boosted,
+ * - has been idle for enough time,
+ * - is not a sync queue or is linked to a bfq_io_cq (it is
+ * shared "for its nature" or it is not shared and its
+ * requests have not been redirected to a shared queue)
+ * start a weight-raising period.
+ */
+ if (old_wr_coeff == 1 && (interactive || soft_rt) &&
+ (!bfq_bfqq_sync(bfqq) || bfqq->bic != NULL)) {
+ bfqq->wr_coeff = bfqd->bfq_wr_coeff;
+ if (interactive)
+ bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
+ else
+ bfqq->wr_cur_max_time =
+ bfqd->bfq_wr_rt_max_time;
+ bfq_log_bfqq(bfqd, bfqq,
+ "wrais starting at %lu, rais_max_time %u",
+ jiffies,
+ jiffies_to_msecs(bfqq->wr_cur_max_time));
+ } else if (old_wr_coeff > 1) {
+ if (interactive)
+ bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
+ else if (coop_or_in_burst ||
+ (bfqq->wr_cur_max_time ==
+ bfqd->bfq_wr_rt_max_time &&
+ !soft_rt)) {
+ bfqq->wr_coeff = 1;
+ bfq_log_bfqq(bfqd, bfqq,
+ "wrais ending at %lu, rais_max_time %u",
+ jiffies,
+ jiffies_to_msecs(bfqq->
+ wr_cur_max_time));
+ } else if (time_before(
+ bfqq->last_wr_start_finish +
+ bfqq->wr_cur_max_time,
+ jiffies +
+ bfqd->bfq_wr_rt_max_time) &&
+ soft_rt) {
+ /*
+ *
+ * The remaining weight-raising time is lower
+ * than bfqd->bfq_wr_rt_max_time, which means
+ * that the application is enjoying weight
+ * raising either because deemed soft-rt in
+ * the near past, or because deemed interactive
+ * a long ago.
+ * In both cases, resetting now the current
+ * remaining weight-raising time for the
+ * application to the weight-raising duration
+ * for soft rt applications would not cause any
+ * latency increase for the application (as the
+ * new duration would be higher than the
+ * remaining time).
+ *
+ * In addition, the application is now meeting
+ * the requirements for being deemed soft rt.
+ * In the end we can correctly and safely
+ * (re)charge the weight-raising duration for
+ * the application with the weight-raising
+ * duration for soft rt applications.
+ *
+ * In particular, doing this recharge now, i.e.,
+ * before the weight-raising period for the
+ * application finishes, reduces the probability
+ * of the following negative scenario:
+ * 1) the weight of a soft rt application is
+ * raised at startup (as for any newly
+ * created application),
+ * 2) since the application is not interactive,
+ * at a certain time weight-raising is
+ * stopped for the application,
+ * 3) at that time the application happens to
+ * still have pending requests, and hence
+ * is destined to not have a chance to be
+ * deemed soft rt before these requests are
+ * completed (see the comments to the
+ * function bfq_bfqq_softrt_next_start()
+ * for details on soft rt detection),
+ * 4) these pending requests experience a high
+ * latency because the application is not
+ * weight-raised while they are pending.
+ */
+ bfqq->last_wr_start_finish = jiffies;
+ bfqq->wr_cur_max_time =
+ bfqd->bfq_wr_rt_max_time;
+ }
+ }
+set_ioprio_changed:
+ if (old_wr_coeff != bfqq->wr_coeff)
+ entity->ioprio_changed = 1;
+add_bfqq_busy:
+ bfqq->last_idle_bklogged = jiffies;
+ bfqq->service_from_backlogged = 0;
+ bfq_clear_bfqq_softrt_update(bfqq);
+ bfq_add_bfqq_busy(bfqd, bfqq);
+ } else {
+ if (bfqd->low_latency && old_wr_coeff == 1 && !rq_is_sync(rq) &&
+ time_is_before_jiffies(
+ bfqq->last_wr_start_finish +
+ bfqd->bfq_wr_min_inter_arr_async)) {
+ bfqq->wr_coeff = bfqd->bfq_wr_coeff;
+ bfqq->wr_cur_max_time = bfq_wr_duration(bfqd);
+
+ bfqd->wr_busy_queues++;
+ entity->ioprio_changed = 1;
+ bfq_log_bfqq(bfqd, bfqq,
+ "non-idle wrais starting at %lu, rais_max_time %u",
+ jiffies,
+ jiffies_to_msecs(bfqq->wr_cur_max_time));
+ }
+ if (prev != bfqq->next_rq)
+ bfq_updated_next_req(bfqd, bfqq);
+ }
+
+ if (bfqd->low_latency &&
+ (old_wr_coeff == 1 || bfqq->wr_coeff == 1 || interactive))
+ bfqq->last_wr_start_finish = jiffies;
+}
+
+static struct request *bfq_find_rq_fmerge(struct bfq_data *bfqd,
+ struct bio *bio)
+{
+ struct task_struct *tsk = current;
+ struct bfq_io_cq *bic;
+ struct bfq_queue *bfqq;
+
+ bic = bfq_bic_lookup(bfqd, tsk->io_context);
+ if (bic == NULL)
+ return NULL;
+
+ bfqq = bic_to_bfqq(bic, bfq_bio_sync(bio));
+ if (bfqq != NULL) {
+ sector_t sector = bio->bi_sector + bio_sectors(bio);
+
+ return elv_rb_find(&bfqq->sort_list, sector);
+ }
+
+ return NULL;
+}
+
+static void bfq_activate_request(struct request_queue *q, struct request *rq)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+
+ bfqd->rq_in_driver++;
+ bfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
+ bfq_log(bfqd, "activate_request: new bfqd->last_position %llu",
+ (long long unsigned)bfqd->last_position);
+}
+
+static inline void bfq_deactivate_request(struct request_queue *q,
+ struct request *rq)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+
+ BUG_ON(bfqd->rq_in_driver == 0);
+ bfqd->rq_in_driver--;
+}
+
+static void bfq_remove_request(struct request *rq)
+{
+ struct bfq_queue *bfqq = RQ_BFQQ(rq);
+ struct bfq_data *bfqd = bfqq->bfqd;
+ const int sync = rq_is_sync(rq);
+
+ if (bfqq->next_rq == rq) {
+ bfqq->next_rq = bfq_find_next_rq(bfqd, bfqq, rq);
+ bfq_updated_next_req(bfqd, bfqq);
+ }
+
+ list_del_init(&rq->queuelist);
+ BUG_ON(bfqq->queued[sync] == 0);
+ bfqq->queued[sync]--;
+ bfqd->queued--;
+ elv_rb_del(&bfqq->sort_list, rq);
+
+ if (RB_EMPTY_ROOT(&bfqq->sort_list)) {
+ if (bfq_bfqq_busy(bfqq) && bfqq != bfqd->in_service_queue)
+ bfq_del_bfqq_busy(bfqd, bfqq, 1);
+ /*
+ * Remove queue from request-position tree as it is empty.
+ */
+ if (bfqq->pos_root != NULL) {
+ rb_erase(&bfqq->pos_node, bfqq->pos_root);
+ bfqq->pos_root = NULL;
+ }
+ }
+
+ if (rq->cmd_flags & REQ_META) {
+ BUG_ON(bfqq->meta_pending == 0);
+ bfqq->meta_pending--;
+ }
+}
+
+static int bfq_merge(struct request_queue *q, struct request **req,
+ struct bio *bio)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+ struct request *__rq;
+
+ __rq = bfq_find_rq_fmerge(bfqd, bio);
+ if (__rq != NULL && elv_rq_merge_ok(__rq, bio)) {
+ *req = __rq;
+ return ELEVATOR_FRONT_MERGE;
+ }
+
+ return ELEVATOR_NO_MERGE;
+}
+
+static void bfq_merged_request(struct request_queue *q, struct request *req,
+ int type)
+{
+ if (type == ELEVATOR_FRONT_MERGE &&
+ rb_prev(&req->rb_node) &&
+ blk_rq_pos(req) <
+ blk_rq_pos(container_of(rb_prev(&req->rb_node),
+ struct request, rb_node))) {
+ struct bfq_queue *bfqq = RQ_BFQQ(req);
+ struct bfq_data *bfqd = bfqq->bfqd;
+ struct request *prev, *next_rq;
+
+ /* Reposition request in its sort_list */
+ elv_rb_del(&bfqq->sort_list, req);
+ elv_rb_add(&bfqq->sort_list, req);
+ /* Choose next request to be served for bfqq */
+ prev = bfqq->next_rq;
+ next_rq = bfq_choose_req(bfqd, bfqq->next_rq, req,
+ bfqd->last_position);
+ BUG_ON(next_rq == NULL);
+ bfqq->next_rq = next_rq;
+ /*
+ * If next_rq changes, update both the queue's budget to
+ * fit the new request and the queue's position in its
+ * rq_pos_tree.
+ */
+ if (prev != bfqq->next_rq) {
+ bfq_updated_next_req(bfqd, bfqq);
+ bfq_rq_pos_tree_add(bfqd, bfqq);
+ }
+ }
+}
+
+static void bfq_merged_requests(struct request_queue *q, struct request *rq,
+ struct request *next)
+{
+ struct bfq_queue *bfqq = RQ_BFQQ(rq);
+
+ /*
+ * Reposition in fifo if next is older than rq.
+ */
+ if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
+ time_before(rq_fifo_time(next), rq_fifo_time(rq))) {
+ list_move(&rq->queuelist, &next->queuelist);
+ rq_set_fifo_time(rq, rq_fifo_time(next));
+ }
+
+ if (bfqq->next_rq == next)
+ bfqq->next_rq = rq;
+
+ bfq_remove_request(next);
+}
+
+/* Must be called with bfqq != NULL */
+static inline void bfq_bfqq_end_wr(struct bfq_queue *bfqq)
+{
+ BUG_ON(bfqq == NULL);
+ if (bfq_bfqq_busy(bfqq))
+ bfqq->bfqd->wr_busy_queues--;
+ bfqq->wr_coeff = 1;
+ bfqq->wr_cur_max_time = 0;
+ /* Trigger a weight change on the next activation of the queue */
+ bfqq->entity.ioprio_changed = 1;
+}
+
+static void bfq_end_wr_async_queues(struct bfq_data *bfqd,
+ struct bfq_group *bfqg)
+{
+ int i, j;
+
+ for (i = 0; i < 2; i++)
+ for (j = 0; j < IOPRIO_BE_NR; j++)
+ if (bfqg->async_bfqq[i][j] != NULL)
+ bfq_bfqq_end_wr(bfqg->async_bfqq[i][j]);
+ if (bfqg->async_idle_bfqq != NULL)
+ bfq_bfqq_end_wr(bfqg->async_idle_bfqq);
+}
+
+static void bfq_end_wr(struct bfq_data *bfqd)
+{
+ struct bfq_queue *bfqq;
+
+ spin_lock_irq(bfqd->queue->queue_lock);
+
+ list_for_each_entry(bfqq, &bfqd->active_list, bfqq_list)
+ bfq_bfqq_end_wr(bfqq);
+ list_for_each_entry(bfqq, &bfqd->idle_list, bfqq_list)
+ bfq_bfqq_end_wr(bfqq);
+ bfq_end_wr_async(bfqd);
+
+ spin_unlock_irq(bfqd->queue->queue_lock);
+}
+
+static inline sector_t bfq_io_struct_pos(void *io_struct, bool request)
+{
+ if (request)
+ return blk_rq_pos(io_struct);
+ else
+ return ((struct bio *)io_struct)->bi_sector;
+}
+
+static inline sector_t bfq_dist_from(sector_t pos1,
+ sector_t pos2)
+{
+ if (pos1 >= pos2)
+ return pos1 - pos2;
+ else
+ return pos2 - pos1;
+}
+
+static inline int bfq_rq_close_to_sector(void *io_struct, bool request,
+ sector_t sector)
+{
+ return bfq_dist_from(bfq_io_struct_pos(io_struct, request), sector) <=
+ BFQQ_SEEK_THR;
+}
+
+static struct bfq_queue *bfqq_close(struct bfq_data *bfqd, sector_t sector)
+{
+ struct rb_root *root = &bfqd->rq_pos_tree;
+ struct rb_node *parent, *node;
+ struct bfq_queue *__bfqq;
+
+ if (RB_EMPTY_ROOT(root))
+ return NULL;
+
+ /*
+ * First, if we find a request starting at the end of the last
+ * request, choose it.
+ */
+ __bfqq = bfq_rq_pos_tree_lookup(bfqd, root, sector, &parent, NULL);
+ if (__bfqq != NULL)
+ return __bfqq;
+
+ /*
+ * If the exact sector wasn't found, the parent of the NULL leaf
+ * will contain the closest sector (rq_pos_tree sorted by
+ * next_request position).
+ */
+ __bfqq = rb_entry(parent, struct bfq_queue, pos_node);
+ if (bfq_rq_close_to_sector(__bfqq->next_rq, true, sector))
+ return __bfqq;
+
+ if (blk_rq_pos(__bfqq->next_rq) < sector)
+ node = rb_next(&__bfqq->pos_node);
+ else
+ node = rb_prev(&__bfqq->pos_node);
+ if (node == NULL)
+ return NULL;
+
+ __bfqq = rb_entry(node, struct bfq_queue, pos_node);
+ if (bfq_rq_close_to_sector(__bfqq->next_rq, true, sector))
+ return __bfqq;
+
+ return NULL;
+}
+
+/*
+ * bfqd - obvious
+ * cur_bfqq - passed in so that we don't decide that the current queue
+ * is closely cooperating with itself
+ * sector - used as a reference point to search for a close queue
+ */
+static struct bfq_queue *bfq_close_cooperator(struct bfq_data *bfqd,
+ struct bfq_queue *cur_bfqq,
+ sector_t sector)
+{
+ struct bfq_queue *bfqq;
+
+ if (bfq_class_idle(cur_bfqq))
+ return NULL;
+ if (!bfq_bfqq_sync(cur_bfqq))
+ return NULL;
+ if (BFQQ_SEEKY(cur_bfqq))
+ return NULL;
+
+ /* If device has only one backlogged bfq_queue, don't search. */
+ if (bfqd->busy_queues == 1)
+ return NULL;
+
+ /*
+ * We should notice if some of the queues are cooperating, e.g.
+ * working closely on the same area of the disk. In that case,
+ * we can group them together and don't waste time idling.
+ */
+ bfqq = bfqq_close(bfqd, sector);
+ if (bfqq == NULL || bfqq == cur_bfqq)
+ return NULL;
+
+ /*
+ * Do not merge queues from different bfq_groups.
+ */
+ if (bfqq->entity.parent != cur_bfqq->entity.parent)
+ return NULL;
+
+ /*
+ * It only makes sense to merge sync queues.
+ */
+ if (!bfq_bfqq_sync(bfqq))
+ return NULL;
+ if (BFQQ_SEEKY(bfqq))
+ return NULL;
+
+ /*
+ * Do not merge queues of different priority classes.
+ */
+ if (bfq_class_rt(bfqq) != bfq_class_rt(cur_bfqq))
+ return NULL;
+
+ return bfqq;
+}
+
+static struct bfq_queue *
+bfq_setup_merge(struct bfq_queue *bfqq, struct bfq_queue *new_bfqq)
+{
+ int process_refs, new_process_refs;
+ struct bfq_queue *__bfqq;
+
+ /*
+ * If there are no process references on the new_bfqq, then it is
+ * unsafe to follow the ->new_bfqq chain as other bfqq's in the chain
+ * may have dropped their last reference (not just their last process
+ * reference).
+ */
+ if (!bfqq_process_refs(new_bfqq))
+ return NULL;
+
+ /* Avoid a circular list and skip interim queue merges. */
+ while ((__bfqq = new_bfqq->new_bfqq)) {
+ if (__bfqq == bfqq)
+ return NULL;
+ new_bfqq = __bfqq;
+ }
+
+ process_refs = bfqq_process_refs(bfqq);
+ new_process_refs = bfqq_process_refs(new_bfqq);
+ /*
+ * If the process for the bfqq has gone away, there is no
+ * sense in merging the queues.
+ */
+ if (process_refs == 0 || new_process_refs == 0)
+ return NULL;
+
+ bfq_log_bfqq(bfqq->bfqd, bfqq, "scheduling merge with queue %d",
+ new_bfqq->pid);
+
+ /*
+ * Merging is just a redirection: the requests of the process
+ * owning one of the two queues are redirected to the other queue.
+ * The latter queue, in its turn, is set as shared if this is the
+ * first time that the requests of some process are redirected to
+ * it.
+ *
+ * We redirect bfqq to new_bfqq and not the opposite, because we
+ * are in the context of the process owning bfqq, hence we have
+ * the io_cq of this process. So we can immediately configure this
+ * io_cq to redirect the requests of the process to new_bfqq.
+ *
+ * NOTE, even if new_bfqq coincides with the in-service queue, the
+ * io_cq of new_bfqq is not available, because, if the in-service
+ * queue is shared, bfqd->in_service_bic may not point to the
+ * io_cq of the in-service queue.
+ * Redirecting the requests of the process owning bfqq to the
+ * currently in-service queue is in any case the best option, as
+ * we feed the in-service queue with new requests close to the
+ * last request served and, by doing so, hopefully increase the
+ * throughput.
+ */
+ bfqq->new_bfqq = new_bfqq;
+ atomic_add(process_refs, &new_bfqq->ref);
+ return new_bfqq;
+}
+
+/*
+ * Attempt to schedule a merge of bfqq with the currently in-service queue
+ * or with a close queue among the scheduled queues.
+ * Return NULL if no merge was scheduled, a pointer to the shared bfq_queue
+ * structure otherwise.
+ *
+ * The OOM queue is not allowed to participate to cooperation: in fact, since
+ * the requests temporarily redirected to the OOM queue could be redirected
+ * again to dedicated queues at any time, the state needed to correctly
+ * handle merging with the OOM queue would be quite complex and expensive
+ * to maintain. Besides, in such a critical condition as an out of memory,
+ * the benefits of queue merging may be little relevant, or even negligible.
+ */
+static struct bfq_queue *
+bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ void *io_struct, bool request)
+{
+ struct bfq_queue *in_service_bfqq, *new_bfqq;
+
+ if (bfqq->new_bfqq)
+ return bfqq->new_bfqq;
+
+ if (!io_struct || unlikely(bfqq == &bfqd->oom_bfqq))
+ return NULL;
+
+ in_service_bfqq = bfqd->in_service_queue;
+
+ if (in_service_bfqq == NULL || in_service_bfqq == bfqq ||
+ !bfqd->in_service_bic ||
+ unlikely(in_service_bfqq == &bfqd->oom_bfqq))
+ goto check_scheduled;
+
+ if (bfq_class_idle(in_service_bfqq) || bfq_class_idle(bfqq))
+ goto check_scheduled;
+
+ if (bfq_class_rt(in_service_bfqq) != bfq_class_rt(bfqq))
+ goto check_scheduled;
+
+ if (in_service_bfqq->entity.parent != bfqq->entity.parent)
+ goto check_scheduled;
+
+ if (bfq_rq_close_to_sector(io_struct, request, bfqd->last_position) &&
+ bfq_bfqq_sync(in_service_bfqq) && bfq_bfqq_sync(bfqq)) {
+ new_bfqq = bfq_setup_merge(bfqq, in_service_bfqq);
+ if (new_bfqq != NULL)
+ return new_bfqq; /* Merge with in-service queue */
+ }
+
+ /*
+ * Check whether there is a cooperator among currently scheduled
+ * queues. The only thing we need is that the bio/request is not
+ * NULL, as we need it to establish whether a cooperator exists.
+ */
+check_scheduled:
+ new_bfqq = bfq_close_cooperator(bfqd, bfqq,
+ bfq_io_struct_pos(io_struct, request));
+ if (new_bfqq && likely(new_bfqq != &bfqd->oom_bfqq))
+ return bfq_setup_merge(bfqq, new_bfqq);
+
+ return NULL;
+}
+
+static inline void
+bfq_bfqq_save_state(struct bfq_queue *bfqq)
+{
+ /*
+ * If bfqq->bic == NULL, the queue is already shared or its requests
+ * have already been redirected to a shared queue; both idle window
+ * and weight raising state have already been saved. Do nothing.
+ */
+ if (bfqq->bic == NULL)
+ return;
+ if (bfqq->bic->wr_time_left)
+ /*
+ * This is the queue of a just-started process, and would
+ * deserve weight raising: we set wr_time_left to the full
+ * weight-raising duration to trigger weight-raising when
+ * and if the queue is split and the first request of the
+ * queue is enqueued.
+ */
+ bfqq->bic->wr_time_left = bfq_wr_duration(bfqq->bfqd);
+ else if (bfqq->wr_coeff > 1) {
+ unsigned long wr_duration =
+ jiffies - bfqq->last_wr_start_finish;
+ /*
+ * It may happen that a queue's weight raising period lasts
+ * longer than its wr_cur_max_time, as weight raising is
+ * handled only when a request is enqueued or dispatched (it
+ * does not use any timer). If the weight raising period is
+ * about to end, don't save it.
+ */
+ if (bfqq->wr_cur_max_time <= wr_duration)
+ bfqq->bic->wr_time_left = 0;
+ else
+ bfqq->bic->wr_time_left =
+ bfqq->wr_cur_max_time - wr_duration;
+ /*
+ * The bfq_queue is becoming shared or the requests of the
+ * process owning the queue are being redirected to a shared
+ * queue. Stop the weight raising period of the queue, as in
+ * both cases it should not be owned by an interactive or
+ * soft real-time application.
+ */
+ bfq_bfqq_end_wr(bfqq);
+ } else
+ bfqq->bic->wr_time_left = 0;
+ bfqq->bic->saved_idle_window = bfq_bfqq_idle_window(bfqq);
+ bfqq->bic->saved_IO_bound = bfq_bfqq_IO_bound(bfqq);
+ bfqq->bic->saved_in_large_burst = bfq_bfqq_in_large_burst(bfqq);
+ bfqq->bic->was_in_burst_list = !hlist_unhashed(&bfqq->burst_list_node);
+ bfqq->bic->cooperations++;
+ bfqq->bic->failed_cooperations = 0;
+}
+
+static inline void
+bfq_get_bic_reference(struct bfq_queue *bfqq)
+{
+ /*
+ * If bfqq->bic has a non-NULL value, the bic to which it belongs
+ * is about to begin using a shared bfq_queue.
+ */
+ if (bfqq->bic)
+ atomic_long_inc(&bfqq->bic->icq.ioc->refcount);
+}
+
+static void
+bfq_merge_bfqqs(struct bfq_data *bfqd, struct bfq_io_cq *bic,
+ struct bfq_queue *bfqq, struct bfq_queue *new_bfqq)
+{
+ bfq_log_bfqq(bfqd, bfqq, "merging with queue %lu",
+ (long unsigned)new_bfqq->pid);
+ /* Save weight raising and idle window of the merged queues */
+ bfq_bfqq_save_state(bfqq);
+ bfq_bfqq_save_state(new_bfqq);
+ if (bfq_bfqq_IO_bound(bfqq))
+ bfq_mark_bfqq_IO_bound(new_bfqq);
+ bfq_clear_bfqq_IO_bound(bfqq);
+ /*
+ * Grab a reference to the bic, to prevent it from being destroyed
+ * before being possibly touched by a bfq_split_bfqq().
+ */
+ bfq_get_bic_reference(bfqq);
+ bfq_get_bic_reference(new_bfqq);
+ /*
+ * Merge queues (that is, let bic redirect its requests to new_bfqq)
+ */
+ bic_set_bfqq(bic, new_bfqq, 1);
+ bfq_mark_bfqq_coop(new_bfqq);
+ /*
+ * new_bfqq now belongs to at least two bics (it is a shared queue):
+ * set new_bfqq->bic to NULL. bfqq either:
+ * - does not belong to any bic any more, and hence bfqq->bic must
+ * be set to NULL, or
+ * - is a queue whose owning bics have already been redirected to a
+ * different queue, hence the queue is destined to not belong to
+ * any bic soon and bfqq->bic is already NULL (therefore the next
+ * assignment causes no harm).
+ */
+ new_bfqq->bic = NULL;
+ bfqq->bic = NULL;
+ bfq_put_queue(bfqq);
+}
+
+static inline void bfq_bfqq_increase_failed_cooperations(struct bfq_queue *bfqq)
+{
+ struct bfq_io_cq *bic = bfqq->bic;
+ struct bfq_data *bfqd = bfqq->bfqd;
+
+ if (bic && bfq_bfqq_cooperations(bfqq) >= bfqd->bfq_coop_thresh) {
+ bic->failed_cooperations++;
+ if (bic->failed_cooperations >= bfqd->bfq_failed_cooperations)
+ bic->cooperations = 0;
+ }
+}
+
+static int bfq_allow_merge(struct request_queue *q, struct request *rq,
+ struct bio *bio)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+ struct bfq_io_cq *bic;
+ struct bfq_queue *bfqq, *new_bfqq;
+
+ /*
+ * Disallow merge of a sync bio into an async request.
+ */
+ if (bfq_bio_sync(bio) && !rq_is_sync(rq))
+ return 0;
+
+ /*
+ * Lookup the bfqq that this bio will be queued with. Allow
+ * merge only if rq is queued there.
+ * Queue lock is held here.
+ */
+ bic = bfq_bic_lookup(bfqd, current->io_context);
+ if (bic == NULL)
+ return 0;
+
+ bfqq = bic_to_bfqq(bic, bfq_bio_sync(bio));
+ /*
+ * We take advantage of this function to perform an early merge
+ * of the queues of possible cooperating processes.
+ */
+ if (bfqq != NULL) {
+ new_bfqq = bfq_setup_cooperator(bfqd, bfqq, bio, false);
+ if (new_bfqq != NULL) {
+ bfq_merge_bfqqs(bfqd, bic, bfqq, new_bfqq);
+ /*
+ * If we get here, the bio will be queued in the
+ * shared queue, i.e., new_bfqq, so use new_bfqq
+ * to decide whether bio and rq can be merged.
+ */
+ bfqq = new_bfqq;
+ } else
+ bfq_bfqq_increase_failed_cooperations(bfqq);
+ }
+
+ return bfqq == RQ_BFQQ(rq);
+}
+
+static void __bfq_set_in_service_queue(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq)
+{
+ if (bfqq != NULL) {
+ bfq_mark_bfqq_must_alloc(bfqq);
+ bfq_mark_bfqq_budget_new(bfqq);
+ bfq_clear_bfqq_fifo_expire(bfqq);
+
+ bfqd->budgets_assigned = (bfqd->budgets_assigned*7 + 256) / 8;
+
+ bfq_log_bfqq(bfqd, bfqq,
+ "set_in_service_queue, cur-budget = %lu",
+ bfqq->entity.budget);
+ }
+
+ bfqd->in_service_queue = bfqq;
+}
+
+/*
+ * Get and set a new queue for service.
+ */
+static struct bfq_queue *bfq_set_in_service_queue(struct bfq_data *bfqd)
+{
+ struct bfq_queue *bfqq = bfq_get_next_queue(bfqd);
+
+ __bfq_set_in_service_queue(bfqd, bfqq);
+ return bfqq;
+}
+
+/*
+ * If enough samples have been computed, return the current max budget
+ * stored in bfqd, which is dynamically updated according to the
+ * estimated disk peak rate; otherwise return the default max budget
+ */
+static inline unsigned long bfq_max_budget(struct bfq_data *bfqd)
+{
+ if (bfqd->budgets_assigned < 194)
+ return bfq_default_max_budget;
+ else
+ return bfqd->bfq_max_budget;
+}
+
+/*
+ * Return min budget, which is a fraction of the current or default
+ * max budget (trying with 1/32)
+ */
+static inline unsigned long bfq_min_budget(struct bfq_data *bfqd)
+{
+ if (bfqd->budgets_assigned < 194)
+ return bfq_default_max_budget / 32;
+ else
+ return bfqd->bfq_max_budget / 32;
+}
+
+static void bfq_arm_slice_timer(struct bfq_data *bfqd)
+{
+ struct bfq_queue *bfqq = bfqd->in_service_queue;
+ struct bfq_io_cq *bic;
+ unsigned long sl;
+
+ BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list));
+
+ /* Processes have exited, don't wait. */
+ bic = bfqd->in_service_bic;
+ if (bic == NULL || atomic_read(&bic->icq.ioc->nr_tasks) == 0)
+ return;
+
+ bfq_mark_bfqq_wait_request(bfqq);
+
+ /*
+ * We don't want to idle for seeks, but we do want to allow
+ * fair distribution of slice time for a process doing back-to-back
+ * seeks. So allow a little bit of time for him to submit a new rq.
+ *
+ * To prevent processes with (partly) seeky workloads from
+ * being too ill-treated, grant them a small fraction of the
+ * assigned budget before reducing the waiting time to
+ * BFQ_MIN_TT. This happened to help reduce latency.
+ */
+ sl = bfqd->bfq_slice_idle;
+ /*
+ * Unless the queue is being weight-raised, grant only minimum idle
+ * time if the queue either has been seeky for long enough or has
+ * already proved to be constantly seeky.
+ */
+ if (bfq_sample_valid(bfqq->seek_samples) &&
+ ((BFQQ_SEEKY(bfqq) && bfqq->entity.service >
+ bfq_max_budget(bfqq->bfqd) / 8) ||
+ bfq_bfqq_constantly_seeky(bfqq)) && bfqq->wr_coeff == 1)
+ sl = min(sl, msecs_to_jiffies(BFQ_MIN_TT));
+ else if (bfqq->wr_coeff > 1)
+ sl = sl * 3;
+ bfqd->last_idling_start = ktime_get();
+ mod_timer(&bfqd->idle_slice_timer, jiffies + sl);
+ bfq_log(bfqd, "arm idle: %u/%u ms",
+ jiffies_to_msecs(sl), jiffies_to_msecs(bfqd->bfq_slice_idle));
+}
+
+/*
+ * Set the maximum time for the in-service queue to consume its
+ * budget. This prevents seeky processes from lowering the disk
+ * throughput (always guaranteed with a time slice scheme as in CFQ).
+ */
+static void bfq_set_budget_timeout(struct bfq_data *bfqd)
+{
+ struct bfq_queue *bfqq = bfqd->in_service_queue;
+ unsigned int timeout_coeff;
+ if (bfqq->wr_cur_max_time == bfqd->bfq_wr_rt_max_time)
+ timeout_coeff = 1;
+ else
+ timeout_coeff = bfqq->entity.weight / bfqq->entity.orig_weight;
+
+ bfqd->last_budget_start = ktime_get();
+
+ bfq_clear_bfqq_budget_new(bfqq);
+ bfqq->budget_timeout = jiffies +
+ bfqd->bfq_timeout[bfq_bfqq_sync(bfqq)] * timeout_coeff;
+
+ bfq_log_bfqq(bfqd, bfqq, "set budget_timeout %u",
+ jiffies_to_msecs(bfqd->bfq_timeout[bfq_bfqq_sync(bfqq)] *
+ timeout_coeff));
+}
+
+/*
+ * Move request from internal lists to the request queue dispatch list.
+ */
+static void bfq_dispatch_insert(struct request_queue *q, struct request *rq)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+ struct bfq_queue *bfqq = RQ_BFQQ(rq);
+
+ /*
+ * For consistency, the next instruction should have been executed
+ * after removing the request from the queue and dispatching it.
+ * We execute instead this instruction before bfq_remove_request()
+ * (and hence introduce a temporary inconsistency), for efficiency.
+ * In fact, in a forced_dispatch, this prevents two counters related
+ * to bfqq->dispatched to risk to be uselessly decremented if bfqq
+ * is not in service, and then to be incremented again after
+ * incrementing bfqq->dispatched.
+ */
+ bfqq->dispatched++;
+ bfq_remove_request(rq);
+ elv_dispatch_sort(q, rq);
+
+ if (bfq_bfqq_sync(bfqq))
+ bfqd->sync_flight++;
+}
+
+/*
+ * Return expired entry, or NULL to just start from scratch in rbtree.
+ */
+static struct request *bfq_check_fifo(struct bfq_queue *bfqq)
+{
+ struct request *rq = NULL;
+
+ if (bfq_bfqq_fifo_expire(bfqq))
+ return NULL;
+
+ bfq_mark_bfqq_fifo_expire(bfqq);
+
+ if (list_empty(&bfqq->fifo))
+ return NULL;
+
+ rq = rq_entry_fifo(bfqq->fifo.next);
+
+ if (time_before(jiffies, rq_fifo_time(rq)))
+ return NULL;
+
+ return rq;
+}
+
+static inline unsigned long bfq_bfqq_budget_left(struct bfq_queue *bfqq)
+{
+ struct bfq_entity *entity = &bfqq->entity;
+ return entity->budget - entity->service;
+}
+
+static void __bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+{
+ BUG_ON(bfqq != bfqd->in_service_queue);
+
+ __bfq_bfqd_reset_in_service(bfqd);
+
+ /*
+ * If this bfqq is shared between multiple processes, check
+ * to make sure that those processes are still issuing I/Os
+ * within the mean seek distance. If not, it may be time to
+ * break the queues apart again.
+ */
+ if (bfq_bfqq_coop(bfqq) && BFQQ_SEEKY(bfqq))
+ bfq_mark_bfqq_split_coop(bfqq);
+
+ if (RB_EMPTY_ROOT(&bfqq->sort_list)) {
+ /*
+ * Overloading budget_timeout field to store the time
+ * at which the queue remains with no backlog; used by
+ * the weight-raising mechanism.
+ */
+ bfqq->budget_timeout = jiffies;
+ bfq_del_bfqq_busy(bfqd, bfqq, 1);
+ } else {
+ bfq_activate_bfqq(bfqd, bfqq);
+ /*
+ * Resort priority tree of potential close cooperators.
+ */
+ bfq_rq_pos_tree_add(bfqd, bfqq);
+ }
+}
+
+/**
+ * __bfq_bfqq_recalc_budget - try to adapt the budget to the @bfqq behavior.
+ * @bfqd: device data.
+ * @bfqq: queue to update.
+ * @reason: reason for expiration.
+ *
+ * Handle the feedback on @bfqq budget. See the body for detailed
+ * comments.
+ */
+static void __bfq_bfqq_recalc_budget(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ enum bfqq_expiration reason)
+{
+ struct request *next_rq;
+ unsigned long budget, min_budget;
+
+ budget = bfqq->max_budget;
+ min_budget = bfq_min_budget(bfqd);
+
+ BUG_ON(bfqq != bfqd->in_service_queue);
+
+ bfq_log_bfqq(bfqd, bfqq, "recalc_budg: last budg %lu, budg left %lu",
+ bfqq->entity.budget, bfq_bfqq_budget_left(bfqq));
+ bfq_log_bfqq(bfqd, bfqq, "recalc_budg: last max_budg %lu, min budg %lu",
+ budget, bfq_min_budget(bfqd));
+ bfq_log_bfqq(bfqd, bfqq, "recalc_budg: sync %d, seeky %d",
+ bfq_bfqq_sync(bfqq), BFQQ_SEEKY(bfqd->in_service_queue));
+
+ if (bfq_bfqq_sync(bfqq)) {
+ switch (reason) {
+ /*
+ * Caveat: in all the following cases we trade latency
+ * for throughput.
+ */
+ case BFQ_BFQQ_TOO_IDLE:
+ /*
+ * This is the only case where we may reduce
+ * the budget: if there is no request of the
+ * process still waiting for completion, then
+ * we assume (tentatively) that the timer has
+ * expired because the batch of requests of
+ * the process could have been served with a
+ * smaller budget. Hence, betting that
+ * process will behave in the same way when it
+ * becomes backlogged again, we reduce its
+ * next budget. As long as we guess right,
+ * this budget cut reduces the latency
+ * experienced by the process.
+ *
+ * However, if there are still outstanding
+ * requests, then the process may have not yet
+ * issued its next request just because it is
+ * still waiting for the completion of some of
+ * the still outstanding ones. So in this
+ * subcase we do not reduce its budget, on the
+ * contrary we increase it to possibly boost
+ * the throughput, as discussed in the
+ * comments to the BUDGET_TIMEOUT case.
+ */
+ if (bfqq->dispatched > 0) /* still outstanding reqs */
+ budget = min(budget * 2, bfqd->bfq_max_budget);
+ else {
+ if (budget > 5 * min_budget)
+ budget -= 4 * min_budget;
+ else
+ budget = min_budget;
+ }
+ break;
+ case BFQ_BFQQ_BUDGET_TIMEOUT:
+ /*
+ * We double the budget here because: 1) it
+ * gives the chance to boost the throughput if
+ * this is not a seeky process (which may have
+ * bumped into this timeout because of, e.g.,
+ * ZBR), 2) together with charge_full_budget
+ * it helps give seeky processes higher
+ * timestamps, and hence be served less
+ * frequently.
+ */
+ budget = min(budget * 2, bfqd->bfq_max_budget);
+ break;
+ case BFQ_BFQQ_BUDGET_EXHAUSTED:
+ /*
+ * The process still has backlog, and did not
+ * let either the budget timeout or the disk
+ * idling timeout expire. Hence it is not
+ * seeky, has a short thinktime and may be
+ * happy with a higher budget too. So
+ * definitely increase the budget of this good
+ * candidate to boost the disk throughput.
+ */
+ budget = min(budget * 4, bfqd->bfq_max_budget);
+ break;
+ case BFQ_BFQQ_NO_MORE_REQUESTS:
+ /*
+ * Leave the budget unchanged.
+ */
+ default:
+ return;
+ }
+ } else /* async queue */
+ /* async queues get always the maximum possible budget
+ * (their ability to dispatch is limited by
+ * @bfqd->bfq_max_budget_async_rq).
+ */
+ budget = bfqd->bfq_max_budget;
+
+ bfqq->max_budget = budget;
+
+ if (bfqd->budgets_assigned >= 194 && bfqd->bfq_user_max_budget == 0 &&
+ bfqq->max_budget > bfqd->bfq_max_budget)
+ bfqq->max_budget = bfqd->bfq_max_budget;
+
+ /*
+ * Make sure that we have enough budget for the next request.
+ * Since the finish time of the bfqq must be kept in sync with
+ * the budget, be sure to call __bfq_bfqq_expire() after the
+ * update.
+ */
+ next_rq = bfqq->next_rq;
+ if (next_rq != NULL)
+ bfqq->entity.budget = max_t(unsigned long, bfqq->max_budget,
+ bfq_serv_to_charge(next_rq, bfqq));
+ else
+ bfqq->entity.budget = bfqq->max_budget;
+
+ bfq_log_bfqq(bfqd, bfqq, "head sect: %u, new budget %lu",
+ next_rq != NULL ? blk_rq_sectors(next_rq) : 0,
+ bfqq->entity.budget);
+}
+
+static unsigned long bfq_calc_max_budget(u64 peak_rate, u64 timeout)
+{
+ unsigned long max_budget;
+
+ /*
+ * The max_budget calculated when autotuning is equal to the
+ * amount of sectors transfered in timeout_sync at the
+ * estimated peak rate.
+ */
+ max_budget = (unsigned long)(peak_rate * 1000 *
+ timeout >> BFQ_RATE_SHIFT);
+
+ return max_budget;
+}
+
+/*
+ * In addition to updating the peak rate, checks whether the process
+ * is "slow", and returns 1 if so. This slow flag is used, in addition
+ * to the budget timeout, to reduce the amount of service provided to
+ * seeky processes, and hence reduce their chances to lower the
+ * throughput. See the code for more details.
+ */
+static int bfq_update_peak_rate(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ int compensate, enum bfqq_expiration reason)
+{
+ u64 bw, usecs, expected, timeout;
+ ktime_t delta;
+ int update = 0;
+
+ if (!bfq_bfqq_sync(bfqq) || bfq_bfqq_budget_new(bfqq))
+ return 0;
+
+ if (compensate)
+ delta = bfqd->last_idling_start;
+ else
+ delta = ktime_get();
+ delta = ktime_sub(delta, bfqd->last_budget_start);
+ usecs = ktime_to_us(delta);
+
+ /* Don't trust short/unrealistic values. */
+ if (usecs < 100 || usecs >= LONG_MAX)
+ return 0;
+
+ /*
+ * Calculate the bandwidth for the last slice. We use a 64 bit
+ * value to store the peak rate, in sectors per usec in fixed
+ * point math. We do so to have enough precision in the estimate
+ * and to avoid overflows.
+ */
+ bw = (u64)bfqq->entity.service << BFQ_RATE_SHIFT;
+ do_div(bw, (unsigned long)usecs);
+
+ timeout = jiffies_to_msecs(bfqd->bfq_timeout[BLK_RW_SYNC]);
+
+ /*
+ * Use only long (> 20ms) intervals to filter out spikes for
+ * the peak rate estimation.
+ */
+ if (usecs > 20000) {
+ if (bw > bfqd->peak_rate ||
+ (!BFQQ_SEEKY(bfqq) &&
+ reason == BFQ_BFQQ_BUDGET_TIMEOUT)) {
+ bfq_log(bfqd, "measured bw =%llu", bw);
+ /*
+ * To smooth oscillations use a low-pass filter with
+ * alpha=7/8, i.e.,
+ * new_rate = (7/8) * old_rate + (1/8) * bw
+ */
+ do_div(bw, 8);
+ if (bw == 0)
+ return 0;
+ bfqd->peak_rate *= 7;
+ do_div(bfqd->peak_rate, 8);
+ bfqd->peak_rate += bw;
+ update = 1;
+ bfq_log(bfqd, "new peak_rate=%llu", bfqd->peak_rate);
+ }
+
+ update |= bfqd->peak_rate_samples == BFQ_PEAK_RATE_SAMPLES - 1;
+
+ if (bfqd->peak_rate_samples < BFQ_PEAK_RATE_SAMPLES)
+ bfqd->peak_rate_samples++;
+
+ if (bfqd->peak_rate_samples == BFQ_PEAK_RATE_SAMPLES &&
+ update) {
+ int dev_type = blk_queue_nonrot(bfqd->queue);
+ if (bfqd->bfq_user_max_budget == 0) {
+ bfqd->bfq_max_budget =
+ bfq_calc_max_budget(bfqd->peak_rate,
+ timeout);
+ bfq_log(bfqd, "new max_budget=%lu",
+ bfqd->bfq_max_budget);
+ }
+ if (bfqd->device_speed == BFQ_BFQD_FAST &&
+ bfqd->peak_rate < device_speed_thresh[dev_type]) {
+ bfqd->device_speed = BFQ_BFQD_SLOW;
+ bfqd->RT_prod = R_slow[dev_type] *
+ T_slow[dev_type];
+ } else if (bfqd->device_speed == BFQ_BFQD_SLOW &&
+ bfqd->peak_rate > device_speed_thresh[dev_type]) {
+ bfqd->device_speed = BFQ_BFQD_FAST;
+ bfqd->RT_prod = R_fast[dev_type] *
+ T_fast[dev_type];
+ }
+ }
+ }
+
+ /*
+ * If the process has been served for a too short time
+ * interval to let its possible sequential accesses prevail on
+ * the initial seek time needed to move the disk head on the
+ * first sector it requested, then give the process a chance
+ * and for the moment return false.
+ */
+ if (bfqq->entity.budget <= bfq_max_budget(bfqd) / 8)
+ return 0;
+
+ /*
+ * A process is considered ``slow'' (i.e., seeky, so that we
+ * cannot treat it fairly in the service domain, as it would
+ * slow down too much the other processes) if, when a slice
+ * ends for whatever reason, it has received service at a
+ * rate that would not be high enough to complete the budget
+ * before the budget timeout expiration.
+ */
+ expected = bw * 1000 * timeout >> BFQ_RATE_SHIFT;
+
+ /*
+ * Caveat: processes doing IO in the slower disk zones will
+ * tend to be slow(er) even if not seeky. And the estimated
+ * peak rate will actually be an average over the disk
+ * surface. Hence, to not be too harsh with unlucky processes,
+ * we keep a budget/3 margin of safety before declaring a
+ * process slow.
+ */
+ return expected > (4 * bfqq->entity.budget) / 3;
+}
+
+/*
+ * To be deemed as soft real-time, an application must meet two
+ * requirements. First, the application must not require an average
+ * bandwidth higher than the approximate bandwidth required to playback or
+ * record a compressed high-definition video.
+ * The next function is invoked on the completion of the last request of a
+ * batch, to compute the next-start time instant, soft_rt_next_start, such
+ * that, if the next request of the application does not arrive before
+ * soft_rt_next_start, then the above requirement on the bandwidth is met.
+ *
+ * The second requirement is that the request pattern of the application is
+ * isochronous, i.e., that, after issuing a request or a batch of requests,
+ * the application stops issuing new requests until all its pending requests
+ * have been completed. After that, the application may issue a new batch,
+ * and so on.
+ * For this reason the next function is invoked to compute
+ * soft_rt_next_start only for applications that meet this requirement,
+ * whereas soft_rt_next_start is set to infinity for applications that do
+ * not.
+ *
+ * Unfortunately, even a greedy application may happen to behave in an
+ * isochronous way if the CPU load is high. In fact, the application may
+ * stop issuing requests while the CPUs are busy serving other processes,
+ * then restart, then stop again for a while, and so on. In addition, if
+ * the disk achieves a low enough throughput with the request pattern
+ * issued by the application (e.g., because the request pattern is random
+ * and/or the device is slow), then the application may meet the above
+ * bandwidth requirement too. To prevent such a greedy application to be
+ * deemed as soft real-time, a further rule is used in the computation of
+ * soft_rt_next_start: soft_rt_next_start must be higher than the current
+ * time plus the maximum time for which the arrival of a request is waited
+ * for when a sync queue becomes idle, namely bfqd->bfq_slice_idle.
+ * This filters out greedy applications, as the latter issue instead their
+ * next request as soon as possible after the last one has been completed
+ * (in contrast, when a batch of requests is completed, a soft real-time
+ * application spends some time processing data).
+ *
+ * Unfortunately, the last filter may easily generate false positives if
+ * only bfqd->bfq_slice_idle is used as a reference time interval and one
+ * or both the following cases occur:
+ * 1) HZ is so low that the duration of a jiffy is comparable to or higher
+ * than bfqd->bfq_slice_idle. This happens, e.g., on slow devices with
+ * HZ=100.
+ * 2) jiffies, instead of increasing at a constant rate, may stop increasing
+ * for a while, then suddenly 'jump' by several units to recover the lost
+ * increments. This seems to happen, e.g., inside virtual machines.
+ * To address this issue, we do not use as a reference time interval just
+ * bfqd->bfq_slice_idle, but bfqd->bfq_slice_idle plus a few jiffies. In
+ * particular we add the minimum number of jiffies for which the filter
+ * seems to be quite precise also in embedded systems and KVM/QEMU virtual
+ * machines.
+ */
+static inline unsigned long bfq_bfqq_softrt_next_start(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq)
+{
+ return max(bfqq->last_idle_bklogged +
+ HZ * bfqq->service_from_backlogged /
+ bfqd->bfq_wr_max_softrt_rate,
+ jiffies + bfqq->bfqd->bfq_slice_idle + 4);
+}
+
+/*
+ * Return the largest-possible time instant such that, for as long as possible,
+ * the current time will be lower than this time instant according to the macro
+ * time_is_before_jiffies().
+ */
+static inline unsigned long bfq_infinity_from_now(unsigned long now)
+{
+ return now + ULONG_MAX / 2;
+}
+
+/**
+ * bfq_bfqq_expire - expire a queue.
+ * @bfqd: device owning the queue.
+ * @bfqq: the queue to expire.
+ * @compensate: if true, compensate for the time spent idling.
+ * @reason: the reason causing the expiration.
+ *
+ *
+ * If the process associated to the queue is slow (i.e., seeky), or in
+ * case of budget timeout, or, finally, if it is async, we
+ * artificially charge it an entire budget (independently of the
+ * actual service it received). As a consequence, the queue will get
+ * higher timestamps than the correct ones upon reactivation, and
+ * hence it will be rescheduled as if it had received more service
+ * than what it actually received. In the end, this class of processes
+ * will receive less service in proportion to how slowly they consume
+ * their budgets (and hence how seriously they tend to lower the
+ * throughput).
+ *
+ * In contrast, when a queue expires because it has been idling for
+ * too much or because it exhausted its budget, we do not touch the
+ * amount of service it has received. Hence when the queue will be
+ * reactivated and its timestamps updated, the latter will be in sync
+ * with the actual service received by the queue until expiration.
+ *
+ * Charging a full budget to the first type of queues and the exact
+ * service to the others has the effect of using the WF2Q+ policy to
+ * schedule the former on a timeslice basis, without violating the
+ * service domain guarantees of the latter.
+ */
+static void bfq_bfqq_expire(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ int compensate,
+ enum bfqq_expiration reason)
+{
+ int slow;
+ BUG_ON(bfqq != bfqd->in_service_queue);
+
+ /* Update disk peak rate for autotuning and check whether the
+ * process is slow (see bfq_update_peak_rate).
+ */
+ slow = bfq_update_peak_rate(bfqd, bfqq, compensate, reason);
+
+ /*
+ * As above explained, 'punish' slow (i.e., seeky), timed-out
+ * and async queues, to favor sequential sync workloads.
+ *
+ * Processes doing I/O in the slower disk zones will tend to be
+ * slow(er) even if not seeky. Hence, since the estimated peak
+ * rate is actually an average over the disk surface, these
+ * processes may timeout just for bad luck. To avoid punishing
+ * them we do not charge a full budget to a process that
+ * succeeded in consuming at least 2/3 of its budget.
+ */
+ if (slow || (reason == BFQ_BFQQ_BUDGET_TIMEOUT &&
+ bfq_bfqq_budget_left(bfqq) >= bfqq->entity.budget / 3))
+ bfq_bfqq_charge_full_budget(bfqq);
+
+ bfqq->service_from_backlogged += bfqq->entity.service;
+
+ if (BFQQ_SEEKY(bfqq) && reason == BFQ_BFQQ_BUDGET_TIMEOUT &&
+ !bfq_bfqq_constantly_seeky(bfqq)) {
+ bfq_mark_bfqq_constantly_seeky(bfqq);
+ if (!blk_queue_nonrot(bfqd->queue))
+ bfqd->const_seeky_busy_in_flight_queues++;
+ }
+
+ if (reason == BFQ_BFQQ_TOO_IDLE &&
+ bfqq->entity.service <= 2 * bfqq->entity.budget / 10 )
+ bfq_clear_bfqq_IO_bound(bfqq);
+
+ if (bfqd->low_latency && bfqq->wr_coeff == 1)
+ bfqq->last_wr_start_finish = jiffies;
+
+ if (bfqd->low_latency && bfqd->bfq_wr_max_softrt_rate > 0 &&
+ RB_EMPTY_ROOT(&bfqq->sort_list)) {
+ /*
+ * If we get here, and there are no outstanding requests,
+ * then the request pattern is isochronous (see the comments
+ * to the function bfq_bfqq_softrt_next_start()). Hence we
+ * can compute soft_rt_next_start. If, instead, the queue
+ * still has outstanding requests, then we have to wait
+ * for the completion of all the outstanding requests to
+ * discover whether the request pattern is actually
+ * isochronous.
+ */
+ if (bfqq->dispatched == 0)
+ bfqq->soft_rt_next_start =
+ bfq_bfqq_softrt_next_start(bfqd, bfqq);
+ else {
+ /*
+ * The application is still waiting for the
+ * completion of one or more requests:
+ * prevent it from possibly being incorrectly
+ * deemed as soft real-time by setting its
+ * soft_rt_next_start to infinity. In fact,
+ * without this assignment, the application
+ * would be incorrectly deemed as soft
+ * real-time if:
+ * 1) it issued a new request before the
+ * completion of all its in-flight
+ * requests, and
+ * 2) at that time, its soft_rt_next_start
+ * happened to be in the past.
+ */
+ bfqq->soft_rt_next_start =
+ bfq_infinity_from_now(jiffies);
+ /*
+ * Schedule an update of soft_rt_next_start to when
+ * the task may be discovered to be isochronous.
+ */
+ bfq_mark_bfqq_softrt_update(bfqq);
+ }
+ }
+
+ bfq_log_bfqq(bfqd, bfqq,
+ "expire (%d, slow %d, num_disp %d, idle_win %d)", reason,
+ slow, bfqq->dispatched, bfq_bfqq_idle_window(bfqq));
+
+ /*
+ * Increase, decrease or leave budget unchanged according to
+ * reason.
+ */
+ __bfq_bfqq_recalc_budget(bfqd, bfqq, reason);
+ __bfq_bfqq_expire(bfqd, bfqq);
+}
+
+/*
+ * Budget timeout is not implemented through a dedicated timer, but
+ * just checked on request arrivals and completions, as well as on
+ * idle timer expirations.
+ */
+static int bfq_bfqq_budget_timeout(struct bfq_queue *bfqq)
+{
+ if (bfq_bfqq_budget_new(bfqq) ||
+ time_before(jiffies, bfqq->budget_timeout))
+ return 0;
+ return 1;
+}
+
+/*
+ * If we expire a queue that is waiting for the arrival of a new
+ * request, we may prevent the fictitious timestamp back-shifting that
+ * allows the guarantees of the queue to be preserved (see [1] for
+ * this tricky aspect). Hence we return true only if this condition
+ * does not hold, or if the queue is slow enough to deserve only to be
+ * kicked off for preserving a high throughput.
+*/
+static inline int bfq_may_expire_for_budg_timeout(struct bfq_queue *bfqq)
+{
+ bfq_log_bfqq(bfqq->bfqd, bfqq,
+ "may_budget_timeout: wait_request %d left %d timeout %d",
+ bfq_bfqq_wait_request(bfqq),
+ bfq_bfqq_budget_left(bfqq) >= bfqq->entity.budget / 3,
+ bfq_bfqq_budget_timeout(bfqq));
+
+ return (!bfq_bfqq_wait_request(bfqq) ||
+ bfq_bfqq_budget_left(bfqq) >= bfqq->entity.budget / 3)
+ &&
+ bfq_bfqq_budget_timeout(bfqq);
+}
+
+/*
+ * Device idling is allowed only for the queues for which this function
+ * returns true. For this reason, the return value of this function plays a
+ * critical role for both throughput boosting and service guarantees. The
+ * return value is computed through a logical expression. In this rather
+ * long comment, we try to briefly describe all the details and motivations
+ * behind the components of this logical expression.
+ *
+ * First, the expression is false if bfqq is not sync, or if: bfqq happened
+ * to become active during a large burst of queue activations, and the
+ * pattern of requests bfqq contains boosts the throughput if bfqq is
+ * expired. In fact, queues that became active during a large burst benefit
+ * only from throughput, as discussed in the comments to bfq_handle_burst.
+ * In this respect, expiring bfqq certainly boosts the throughput on NCQ-
+ * capable flash-based devices, whereas, on rotational devices, it boosts
+ * the throughput only if bfqq contains random requests.
+ *
+ * On the opposite end, if (a) bfqq is sync, (b) the above burst-related
+ * condition does not hold, and (c) bfqq is being weight-raised, then the
+ * expression always evaluates to true, as device idling is instrumental
+ * for preserving low-latency guarantees (see [1]). If, instead, conditions
+ * (a) and (b) do hold, but (c) does not, then the expression evaluates to
+ * true only if: (1) bfqq is I/O-bound and has a non-null idle window, and
+ * (2) at least one of the following two conditions holds.
+ * The first condition is that the device is not performing NCQ, because
+ * idling the device most certainly boosts the throughput if this condition
+ * holds and bfqq is I/O-bound and has been granted a non-null idle window.
+ * The second compound condition is made of the logical AND of two components.
+ *
+ * The first component is true only if there is no weight-raised busy
+ * queue. This guarantees that the device is not idled for a sync non-
+ * weight-raised queue when there are busy weight-raised queues. The former
+ * is then expired immediately if empty. Combined with the timestamping
+ * rules of BFQ (see [1] for details), this causes sync non-weight-raised
+ * queues to get a lower number of requests served, and hence to ask for a
+ * lower number of requests from the request pool, before the busy weight-
+ * raised queues get served again.
+ *
+ * This is beneficial for the processes associated with weight-raised
+ * queues, when the request pool is saturated (e.g., in the presence of
+ * write hogs). In fact, if the processes associated with the other queues
+ * ask for requests at a lower rate, then weight-raised processes have a
+ * higher probability to get a request from the pool immediately (or at
+ * least soon) when they need one. Hence they have a higher probability to
+ * actually get a fraction of the disk throughput proportional to their
+ * high weight. This is especially true with NCQ-capable drives, which
+ * enqueue several requests in advance and further reorder internally-
+ * queued requests.
+ *
+ * In the end, mistreating non-weight-raised queues when there are busy
+ * weight-raised queues seems to mitigate starvation problems in the
+ * presence of heavy write workloads and NCQ, and hence to guarantee a
+ * higher application and system responsiveness in these hostile scenarios.
+ *
+ * If the first component of the compound condition is instead true, i.e.,
+ * there is no weight-raised busy queue, then the second component of the
+ * compound condition takes into account service-guarantee and throughput
+ * issues related to NCQ (recall that the compound condition is evaluated
+ * only if the device is detected as supporting NCQ).
+ *
+ * As for service guarantees, allowing the drive to enqueue more than one
+ * request at a time, and hence delegating de facto final scheduling
+ * decisions to the drive's internal scheduler, causes loss of control on
+ * the actual request service order. In this respect, when the drive is
+ * allowed to enqueue more than one request at a time, the service
+ * distribution enforced by the drive's internal scheduler is likely to
+ * coincide with the desired device-throughput distribution only in the
+ * following, perfectly symmetric, scenario:
+ * 1) all active queues have the same weight,
+ * 2) all active groups at the same level in the groups tree have the same
+ * weight,
+ * 3) all active groups at the same level in the groups tree have the same
+ * number of children.
+ *
+ * Even in such a scenario, sequential I/O may still receive a preferential
+ * treatment, but this is not likely to be a big issue with flash-based
+ * devices, because of their non-dramatic loss of throughput with random
+ * I/O. Things do differ with HDDs, for which additional care is taken, as
+ * explained after completing the discussion for flash-based devices.
+ *
+ * Unfortunately, keeping the necessary state for evaluating exactly the
+ * above symmetry conditions would be quite complex and time-consuming.
+ * Therefore BFQ evaluates instead the following stronger sub-conditions,
+ * for which it is much easier to maintain the needed state:
+ * 1) all active queues have the same weight,
+ * 2) all active groups have the same weight,
+ * 3) all active groups have at most one active child each.
+ * In particular, the last two conditions are always true if hierarchical
+ * support and the cgroups interface are not enabled, hence no state needs
+ * to be maintained in this case.
+ *
+ * According to the above considerations, the second component of the
+ * compound condition evaluates to true if any of the above symmetry
+ * sub-condition does not hold, or the device is not flash-based. Therefore,
+ * if also the first component is true, then idling is allowed for a sync
+ * queue. These are the only sub-conditions considered if the device is
+ * flash-based, as, for such a device, it is sensible to force idling only
+ * for service-guarantee issues. In fact, as for throughput, idling
+ * NCQ-capable flash-based devices would not boost the throughput even
+ * with sequential I/O; rather it would lower the throughput in proportion
+ * to how fast the device is. In the end, (only) if all the three
+ * sub-conditions hold and the device is flash-based, the compound
+ * condition evaluates to false and therefore no idling is performed.
+ *
+ * As already said, things change with a rotational device, where idling
+ * boosts the throughput with sequential I/O (even with NCQ). Hence, for
+ * such a device the second component of the compound condition evaluates
+ * to true also if the following additional sub-condition does not hold:
+ * the queue is constantly seeky. Unfortunately, this different behavior
+ * with respect to flash-based devices causes an additional asymmetry: if
+ * some sync queues enjoy idling and some other sync queues do not, then
+ * the latter get a low share of the device throughput, simply because the
+ * former get many requests served after being set as in service, whereas
+ * the latter do not. As a consequence, to guarantee the desired throughput
+ * distribution, on HDDs the compound expression evaluates to true (and
+ * hence device idling is performed) also if the following last symmetry
+ * condition does not hold: no other queue is benefiting from idling. Also
+ * this last condition is actually replaced with a simpler-to-maintain and
+ * stronger condition: there is no busy queue which is not constantly seeky
+ * (and hence may also benefit from idling).
+ *
+ * To sum up, when all the required symmetry and throughput-boosting
+ * sub-conditions hold, the second component of the compound condition
+ * evaluates to false, and hence no idling is performed. This helps to
+ * keep the drives' internal queues full on NCQ-capable devices, and hence
+ * to boost the throughput, without causing 'almost' any loss of service
+ * guarantees. The 'almost' follows from the fact that, if the internal
+ * queue of one such device is filled while all the sub-conditions hold,
+ * but at some point in time some sub-condition stops to hold, then it may
+ * become impossible to let requests be served in the new desired order
+ * until all the requests already queued in the device have been served.
+ */
+static inline bool bfq_bfqq_must_not_expire(struct bfq_queue *bfqq)
+{
+ struct bfq_data *bfqd = bfqq->bfqd;
+#ifdef CONFIG_CGROUP_BFQIO
+#define symmetric_scenario (!bfqd->active_numerous_groups && \
+ !bfq_differentiated_weights(bfqd))
+#else
+#define symmetric_scenario (!bfq_differentiated_weights(bfqd))
+#endif
+#define cond_for_seeky_on_ncq_hdd (bfq_bfqq_constantly_seeky(bfqq) && \
+ bfqd->busy_in_flight_queues == \
+ bfqd->const_seeky_busy_in_flight_queues)
+
+#define cond_for_expiring_in_burst (bfq_bfqq_in_large_burst(bfqq) && \
+ bfqd->hw_tag && \
+ (blk_queue_nonrot(bfqd->queue) || \
+ bfq_bfqq_constantly_seeky(bfqq)))
+
+/*
+ * Condition for expiring a non-weight-raised queue (and hence not idling
+ * the device).
+ */
+#define cond_for_expiring_non_wr (bfqd->hw_tag && \
+ (bfqd->wr_busy_queues > 0 || \
+ (symmetric_scenario && \
+ (blk_queue_nonrot(bfqd->queue) || \
+ cond_for_seeky_on_ncq_hdd))))
+
+ return bfq_bfqq_sync(bfqq) &&
+ !cond_for_expiring_in_burst &&
+ (bfqq->wr_coeff > 1 ||
+ (bfq_bfqq_IO_bound(bfqq) && bfq_bfqq_idle_window(bfqq) &&
+ !cond_for_expiring_non_wr)
+ );
+}
+
+/*
+ * If the in-service queue is empty but sync, and the function
+ * bfq_bfqq_must_not_expire returns true, then:
+ * 1) the queue must remain in service and cannot be expired, and
+ * 2) the disk must be idled to wait for the possible arrival of a new
+ * request for the queue.
+ * See the comments to the function bfq_bfqq_must_not_expire for the reasons
+ * why performing device idling is the best choice to boost the throughput
+ * and preserve service guarantees when bfq_bfqq_must_not_expire itself
+ * returns true.
+ */
+static inline bool bfq_bfqq_must_idle(struct bfq_queue *bfqq)
+{
+ struct bfq_data *bfqd = bfqq->bfqd;
+
+ return RB_EMPTY_ROOT(&bfqq->sort_list) && bfqd->bfq_slice_idle != 0 &&
+ bfq_bfqq_must_not_expire(bfqq);
+}
+
+/*
+ * Select a queue for service. If we have a current queue in service,
+ * check whether to continue servicing it, or retrieve and set a new one.
+ */
+static struct bfq_queue *bfq_select_queue(struct bfq_data *bfqd)
+{
+ struct bfq_queue *bfqq;
+ struct request *next_rq;
+ enum bfqq_expiration reason = BFQ_BFQQ_BUDGET_TIMEOUT;
+
+ bfqq = bfqd->in_service_queue;
+ if (bfqq == NULL)
+ goto new_queue;
+
+ bfq_log_bfqq(bfqd, bfqq, "select_queue: already in-service queue");
+
+ if (bfq_may_expire_for_budg_timeout(bfqq) &&
+ !timer_pending(&bfqd->idle_slice_timer) &&
+ !bfq_bfqq_must_idle(bfqq))
+ goto expire;
+
+ next_rq = bfqq->next_rq;
+ /*
+ * If bfqq has requests queued and it has enough budget left to
+ * serve them, keep the queue, otherwise expire it.
+ */
+ if (next_rq != NULL) {
+ if (bfq_serv_to_charge(next_rq, bfqq) >
+ bfq_bfqq_budget_left(bfqq)) {
+ reason = BFQ_BFQQ_BUDGET_EXHAUSTED;
+ goto expire;
+ } else {
+ /*
+ * The idle timer may be pending because we may
+ * not disable disk idling even when a new request
+ * arrives.
+ */
+ if (timer_pending(&bfqd->idle_slice_timer)) {
+ /*
+ * If we get here: 1) at least a new request
+ * has arrived but we have not disabled the
+ * timer because the request was too small,
+ * 2) then the block layer has unplugged
+ * the device, causing the dispatch to be
+ * invoked.
+ *
+ * Since the device is unplugged, now the
+ * requests are probably large enough to
+ * provide a reasonable throughput.
+ * So we disable idling.
+ */
+ bfq_clear_bfqq_wait_request(bfqq);
+ del_timer(&bfqd->idle_slice_timer);
+ }
+ goto keep_queue;
+ }
+ }
+
+ /*
+ * No requests pending. If the in-service queue still has requests
+ * in flight (possibly waiting for a completion) or is idling for a
+ * new request, then keep it.
+ */
+ if (timer_pending(&bfqd->idle_slice_timer) ||
+ (bfqq->dispatched != 0 && bfq_bfqq_must_not_expire(bfqq))) {
+ bfqq = NULL;
+ goto keep_queue;
+ }
+
+ reason = BFQ_BFQQ_NO_MORE_REQUESTS;
+expire:
+ bfq_bfqq_expire(bfqd, bfqq, 0, reason);
+new_queue:
+ bfqq = bfq_set_in_service_queue(bfqd);
+ bfq_log(bfqd, "select_queue: new queue %d returned",
+ bfqq != NULL ? bfqq->pid : 0);
+keep_queue:
+ return bfqq;
+}
+
+static void bfq_update_wr_data(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+{
+ struct bfq_entity *entity = &bfqq->entity;
+ if (bfqq->wr_coeff > 1) { /* queue is being weight-raised */
+ bfq_log_bfqq(bfqd, bfqq,
+ "raising period dur %u/%u msec, old coeff %u, w %d(%d)",
+ jiffies_to_msecs(jiffies - bfqq->last_wr_start_finish),
+ jiffies_to_msecs(bfqq->wr_cur_max_time),
+ bfqq->wr_coeff,
+ bfqq->entity.weight, bfqq->entity.orig_weight);
+
+ BUG_ON(bfqq != bfqd->in_service_queue && entity->weight !=
+ entity->orig_weight * bfqq->wr_coeff);
+ if (entity->ioprio_changed)
+ bfq_log_bfqq(bfqd, bfqq, "WARN: pending prio change");
+
+ /*
+ * If the queue was activated in a burst, or
+ * too much time has elapsed from the beginning
+ * of this weight-raising period, or the queue has
+ * exceeded the acceptable number of cooperations,
+ * then end weight raising.
+ */
+ if (bfq_bfqq_in_large_burst(bfqq) ||
+ bfq_bfqq_cooperations(bfqq) >= bfqd->bfq_coop_thresh ||
+ time_is_before_jiffies(bfqq->last_wr_start_finish +
+ bfqq->wr_cur_max_time)) {
+ bfqq->last_wr_start_finish = jiffies;
+ bfq_log_bfqq(bfqd, bfqq,
+ "wrais ending at %lu, rais_max_time %u",
+ bfqq->last_wr_start_finish,
+ jiffies_to_msecs(bfqq->wr_cur_max_time));
+ bfq_bfqq_end_wr(bfqq);
+ }
+ }
+ /* Update weight both if it must be raised and if it must be lowered */
+ if ((entity->weight > entity->orig_weight) != (bfqq->wr_coeff > 1))
+ __bfq_entity_update_weight_prio(
+ bfq_entity_service_tree(entity),
+ entity);
+}
+
+/*
+ * Dispatch one request from bfqq, moving it to the request queue
+ * dispatch list.
+ */
+static int bfq_dispatch_request(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq)
+{
+ int dispatched = 0;
+ struct request *rq;
+ unsigned long service_to_charge;
+
+ BUG_ON(RB_EMPTY_ROOT(&bfqq->sort_list));
+
+ /* Follow expired path, else get first next available. */
+ rq = bfq_check_fifo(bfqq);
+ if (rq == NULL)
+ rq = bfqq->next_rq;
+ service_to_charge = bfq_serv_to_charge(rq, bfqq);
+
+ if (service_to_charge > bfq_bfqq_budget_left(bfqq)) {
+ /*
+ * This may happen if the next rq is chosen in fifo order
+ * instead of sector order. The budget is properly
+ * dimensioned to be always sufficient to serve the next
+ * request only if it is chosen in sector order. The reason
+ * is that it would be quite inefficient and little useful
+ * to always make sure that the budget is large enough to
+ * serve even the possible next rq in fifo order.
+ * In fact, requests are seldom served in fifo order.
+ *
+ * Expire the queue for budget exhaustion, and make sure
+ * that the next act_budget is enough to serve the next
+ * request, even if it comes from the fifo expired path.
+ */
+ bfqq->next_rq = rq;
+ /*
+ * Since this dispatch is failed, make sure that
+ * a new one will be performed
+ */
+ if (!bfqd->rq_in_driver)
+ bfq_schedule_dispatch(bfqd);
+ goto expire;
+ }
+
+ /* Finally, insert request into driver dispatch list. */
+ bfq_bfqq_served(bfqq, service_to_charge);
+ bfq_dispatch_insert(bfqd->queue, rq);
+
+ bfq_update_wr_data(bfqd, bfqq);
+
+ bfq_log_bfqq(bfqd, bfqq,
+ "dispatched %u sec req (%llu), budg left %lu",
+ blk_rq_sectors(rq),
+ (long long unsigned)blk_rq_pos(rq),
+ bfq_bfqq_budget_left(bfqq));
+
+ dispatched++;
+
+ if (bfqd->in_service_bic == NULL) {
+ atomic_long_inc(&RQ_BIC(rq)->icq.ioc->refcount);
+ bfqd->in_service_bic = RQ_BIC(rq);
+ }
+
+ if (bfqd->busy_queues > 1 && ((!bfq_bfqq_sync(bfqq) &&
+ dispatched >= bfqd->bfq_max_budget_async_rq) ||
+ bfq_class_idle(bfqq)))
+ goto expire;
+
+ return dispatched;
+
+expire:
+ bfq_bfqq_expire(bfqd, bfqq, 0, BFQ_BFQQ_BUDGET_EXHAUSTED);
+ return dispatched;
+}
+
+static int __bfq_forced_dispatch_bfqq(struct bfq_queue *bfqq)
+{
+ int dispatched = 0;
+
+ while (bfqq->next_rq != NULL) {
+ bfq_dispatch_insert(bfqq->bfqd->queue, bfqq->next_rq);
+ dispatched++;
+ }
+
+ BUG_ON(!list_empty(&bfqq->fifo));
+ return dispatched;
+}
+
+/*
+ * Drain our current requests.
+ * Used for barriers and when switching io schedulers on-the-fly.
+ */
+static int bfq_forced_dispatch(struct bfq_data *bfqd)
+{
+ struct bfq_queue *bfqq, *n;
+ struct bfq_service_tree *st;
+ int dispatched = 0;
+
+ bfqq = bfqd->in_service_queue;
+ if (bfqq != NULL)
+ __bfq_bfqq_expire(bfqd, bfqq);
+
+ /*
+ * Loop through classes, and be careful to leave the scheduler
+ * in a consistent state, as feedback mechanisms and vtime
+ * updates cannot be disabled during the process.
+ */
+ list_for_each_entry_safe(bfqq, n, &bfqd->active_list, bfqq_list) {
+ st = bfq_entity_service_tree(&bfqq->entity);
+
+ dispatched += __bfq_forced_dispatch_bfqq(bfqq);
+ bfqq->max_budget = bfq_max_budget(bfqd);
+
+ bfq_forget_idle(st);
+ }
+
+ BUG_ON(bfqd->busy_queues != 0);
+
+ return dispatched;
+}
+
+static int bfq_dispatch_requests(struct request_queue *q, int force)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+ struct bfq_queue *bfqq;
+ int max_dispatch;
+
+ bfq_log(bfqd, "dispatch requests: %d busy queues", bfqd->busy_queues);
+ if (bfqd->busy_queues == 0)
+ return 0;
+
+ if (unlikely(force))
+ return bfq_forced_dispatch(bfqd);
+
+ bfqq = bfq_select_queue(bfqd);
+ if (bfqq == NULL)
+ return 0;
+
+ max_dispatch = bfqd->bfq_quantum;
+ if (bfq_class_idle(bfqq))
+ max_dispatch = 1;
+
+ if (!bfq_bfqq_sync(bfqq))
+ max_dispatch = bfqd->bfq_max_budget_async_rq;
+
+ if (bfqq->dispatched >= max_dispatch) {
+ if (bfqd->busy_queues > 1)
+ return 0;
+ if (bfqq->dispatched >= 4 * max_dispatch)
+ return 0;
+ }
+
+ if (bfqd->sync_flight != 0 && !bfq_bfqq_sync(bfqq))
+ return 0;
+
+ bfq_clear_bfqq_wait_request(bfqq);
+ BUG_ON(timer_pending(&bfqd->idle_slice_timer));
+
+ if (!bfq_dispatch_request(bfqd, bfqq))
+ return 0;
+
+ bfq_log_bfqq(bfqd, bfqq, "dispatched one request of %d (max_disp %d)",
+ bfqq->pid, max_dispatch);
+
+ return 1;
+}
+
+/*
+ * Task holds one reference to the queue, dropped when task exits. Each rq
+ * in-flight on this queue also holds a reference, dropped when rq is freed.
+ *
+ * Queue lock must be held here.
+ */
+static void bfq_put_queue(struct bfq_queue *bfqq)
+{
+ struct bfq_data *bfqd = bfqq->bfqd;
+
+ BUG_ON(atomic_read(&bfqq->ref) <= 0);
+
+ bfq_log_bfqq(bfqd, bfqq, "put_queue: %p %d", bfqq,
+ atomic_read(&bfqq->ref));
+ if (!atomic_dec_and_test(&bfqq->ref))
+ return;
+
+ BUG_ON(rb_first(&bfqq->sort_list) != NULL);
+ BUG_ON(bfqq->allocated[READ] + bfqq->allocated[WRITE] != 0);
+ BUG_ON(bfqq->entity.tree != NULL);
+ BUG_ON(bfq_bfqq_busy(bfqq));
+ BUG_ON(bfqd->in_service_queue == bfqq);
+
+ if (bfq_bfqq_sync(bfqq))
+ /*
+ * The fact that this queue is being destroyed does not
+ * invalidate the fact that this queue may have been
+ * activated during the current burst. As a consequence,
+ * although the queue does not exist anymore, and hence
+ * needs to be removed from the burst list if there,
+ * the burst size has not to be decremented.
+ */
+ hlist_del_init(&bfqq->burst_list_node);
+
+ bfq_log_bfqq(bfqd, bfqq, "put_queue: %p freed", bfqq);
+
+ kmem_cache_free(bfq_pool, bfqq);
+}
+
+static void bfq_put_cooperator(struct bfq_queue *bfqq)
+{
+ struct bfq_queue *__bfqq, *next;
+
+ /*
+ * If this queue was scheduled to merge with another queue, be
+ * sure to drop the reference taken on that queue (and others in
+ * the merge chain). See bfq_setup_merge and bfq_merge_bfqqs.
+ */
+ __bfqq = bfqq->new_bfqq;
+ while (__bfqq) {
+ if (__bfqq == bfqq)
+ break;
+ next = __bfqq->new_bfqq;
+ bfq_put_queue(__bfqq);
+ __bfqq = next;
+ }
+}
+
+static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+{
+ if (bfqq == bfqd->in_service_queue) {
+ __bfq_bfqq_expire(bfqd, bfqq);
+ bfq_schedule_dispatch(bfqd);
+ }
+
+ bfq_log_bfqq(bfqd, bfqq, "exit_bfqq: %p, %d", bfqq,
+ atomic_read(&bfqq->ref));
+
+ bfq_put_cooperator(bfqq);
+
+ bfq_put_queue(bfqq);
+}
+
+static inline void bfq_init_icq(struct io_cq *icq)
+{
+ struct bfq_io_cq *bic = icq_to_bic(icq);
+
+ bic->ttime.last_end_request = jiffies;
+ /*
+ * A newly created bic indicates that the process has just
+ * started doing I/O, and is probably mapping into memory its
+ * executable and libraries: it definitely needs weight raising.
+ * There is however the possibility that the process performs,
+ * for a while, I/O close to some other process. EQM intercepts
+ * this behavior and may merge the queue corresponding to the
+ * process with some other queue, BEFORE the weight of the queue
+ * is raised. Merged queues are not weight-raised (they are assumed
+ * to belong to processes that benefit only from high throughput).
+ * If the merge is basically the consequence of an accident, then
+ * the queue will be split soon and will get back its old weight.
+ * It is then important to write down somewhere that this queue
+ * does need weight raising, even if it did not make it to get its
+ * weight raised before being merged. To this purpose, we overload
+ * the field raising_time_left and assign 1 to it, to mark the queue
+ * as needing weight raising.
+ */
+ bic->wr_time_left = 1;
+}
+
+static void bfq_exit_icq(struct io_cq *icq)
+{
+ struct bfq_io_cq *bic = icq_to_bic(icq);
+ struct bfq_data *bfqd = bic_to_bfqd(bic);
+
+ if (bic->bfqq[BLK_RW_ASYNC]) {
+ bfq_exit_bfqq(bfqd, bic->bfqq[BLK_RW_ASYNC]);
+ bic->bfqq[BLK_RW_ASYNC] = NULL;
+ }
+
+ if (bic->bfqq[BLK_RW_SYNC]) {
+ /*
+ * If the bic is using a shared queue, put the reference
+ * taken on the io_context when the bic started using a
+ * shared bfq_queue.
+ */
+ if (bfq_bfqq_coop(bic->bfqq[BLK_RW_SYNC]))
+ put_io_context(icq->ioc);
+ bfq_exit_bfqq(bfqd, bic->bfqq[BLK_RW_SYNC]);
+ bic->bfqq[BLK_RW_SYNC] = NULL;
+ }
+}
+
+/*
+ * Update the entity prio values; note that the new values will not
+ * be used until the next (re)activation.
+ */
+static void bfq_init_prio_data(struct bfq_queue *bfqq, struct io_context *ioc)
+{
+ struct task_struct *tsk = current;
+ int ioprio_class;
+
+ if (!bfq_bfqq_prio_changed(bfqq))
+ return;
+
+ ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio);
+ switch (ioprio_class) {
+ default:
+ dev_err(bfqq->bfqd->queue->backing_dev_info.dev,
+ "bfq: bad prio class %d\n", ioprio_class);
+ case IOPRIO_CLASS_NONE:
+ /*
+ * No prio set, inherit CPU scheduling settings.
+ */
+ bfqq->entity.new_ioprio = task_nice_ioprio(tsk);
+ bfqq->entity.new_ioprio_class = task_nice_ioclass(tsk);
+ break;
+ case IOPRIO_CLASS_RT:
+ bfqq->entity.new_ioprio = task_ioprio(ioc);
+ bfqq->entity.new_ioprio_class = IOPRIO_CLASS_RT;
+ break;
+ case IOPRIO_CLASS_BE:
+ bfqq->entity.new_ioprio = task_ioprio(ioc);
+ bfqq->entity.new_ioprio_class = IOPRIO_CLASS_BE;
+ break;
+ case IOPRIO_CLASS_IDLE:
+ bfqq->entity.new_ioprio_class = IOPRIO_CLASS_IDLE;
+ bfqq->entity.new_ioprio = 7;
+ bfq_clear_bfqq_idle_window(bfqq);
+ break;
+ }
+
+ if (bfqq->entity.new_ioprio < 0 ||
+ bfqq->entity.new_ioprio >= IOPRIO_BE_NR) {
+ printk(KERN_CRIT "bfq_init_prio_data: new_ioprio %d\n",
+ bfqq->entity.new_ioprio);
+ BUG();
+ }
+
+ bfqq->entity.ioprio_changed = 1;
+
+ bfq_clear_bfqq_prio_changed(bfqq);
+}
+
+static void bfq_changed_ioprio(struct io_context *ioc,
+ struct bfq_io_cq *bic)
+{
+ struct bfq_data *bfqd;
+ struct bfq_queue *bfqq, *new_bfqq;
+ struct bfq_group *bfqg;
+ unsigned long uninitialized_var(flags);
+
+ bfqd = bfq_get_bfqd_locked(&(bic->icq.q->elevator->elevator_data),
+ &flags);
+ if (unlikely(bfqd == NULL))
+ return;
+
+ bfqq = bic->bfqq[BLK_RW_ASYNC];
+ if (bfqq != NULL) {
+ bfqg = container_of(bfqq->entity.sched_data, struct bfq_group,
+ sched_data);
+ new_bfqq = bfq_get_queue(bfqd, bfqg, BLK_RW_ASYNC, bic->icq.ioc,
+ GFP_ATOMIC);
+ if (new_bfqq != NULL) {
+ bic->bfqq[BLK_RW_ASYNC] = new_bfqq;
+ bfq_log_bfqq(bfqd, bfqq,
+ "changed_ioprio: bfqq %p %d",
+ bfqq, atomic_read(&bfqq->ref));
+ bfq_put_queue(bfqq);
+ }
+ }
+
+ bfqq = bic->bfqq[BLK_RW_SYNC];
+ if (bfqq != NULL)
+ bfq_mark_bfqq_prio_changed(bfqq);
+
+ bfq_put_bfqd_unlock(bfqd, &flags);
+}
+
+static void bfq_init_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ pid_t pid, int is_sync)
+{
+ RB_CLEAR_NODE(&bfqq->entity.rb_node);
+ INIT_LIST_HEAD(&bfqq->fifo);
+ INIT_HLIST_NODE(&bfqq->burst_list_node);
+
+ atomic_set(&bfqq->ref, 0);
+ bfqq->bfqd = bfqd;
+
+ bfq_mark_bfqq_prio_changed(bfqq);
+
+ if (is_sync) {
+ if (!bfq_class_idle(bfqq))
+ bfq_mark_bfqq_idle_window(bfqq);
+ bfq_mark_bfqq_sync(bfqq);
+ }
+ bfq_mark_bfqq_IO_bound(bfqq);
+
+ /* Tentative initial value to trade off between thr and lat */
+ bfqq->max_budget = (2 * bfq_max_budget(bfqd)) / 3;
+ bfqq->pid = pid;
+
+ bfqq->wr_coeff = 1;
+ bfqq->last_wr_start_finish = 0;
+ /*
+ * Set to the value for which bfqq will not be deemed as
+ * soft rt when it becomes backlogged.
+ */
+ bfqq->soft_rt_next_start = bfq_infinity_from_now(jiffies);
+}
+
+static struct bfq_queue *bfq_find_alloc_queue(struct bfq_data *bfqd,
+ struct bfq_group *bfqg,
+ int is_sync,
+ struct io_context *ioc,
+ gfp_t gfp_mask)
+{
+ struct bfq_queue *bfqq, *new_bfqq = NULL;
+ struct bfq_io_cq *bic;
+
+retry:
+ bic = bfq_bic_lookup(bfqd, ioc);
+ /* bic always exists here */
+ bfqq = bic_to_bfqq(bic, is_sync);
+
+ /*
+ * Always try a new alloc if we fall back to the OOM bfqq
+ * originally, since it should just be a temporary situation.
+ */
+ if (bfqq == NULL || bfqq == &bfqd->oom_bfqq) {
+ bfqq = NULL;
+ if (new_bfqq != NULL) {
+ bfqq = new_bfqq;
+ new_bfqq = NULL;
+ } else if (gfp_mask & __GFP_WAIT) {
+ spin_unlock_irq(bfqd->queue->queue_lock);
+ new_bfqq = kmem_cache_alloc_node(bfq_pool,
+ gfp_mask | __GFP_ZERO,
+ bfqd->queue->node);
+ spin_lock_irq(bfqd->queue->queue_lock);
+ if (new_bfqq != NULL)
+ goto retry;
+ } else {
+ bfqq = kmem_cache_alloc_node(bfq_pool,
+ gfp_mask | __GFP_ZERO,
+ bfqd->queue->node);
+ }
+
+ if (bfqq != NULL) {
+ bfq_init_bfqq(bfqd, bfqq, current->pid, is_sync);
+ bfq_init_prio_data(bfqq, ioc);
+ bfq_init_entity(&bfqq->entity, bfqg);
+ bfq_log_bfqq(bfqd, bfqq, "allocated");
+ } else {
+ bfqq = &bfqd->oom_bfqq;
+ bfq_log_bfqq(bfqd, bfqq, "using oom bfqq");
+ }
+ }
+
+ if (new_bfqq != NULL)
+ kmem_cache_free(bfq_pool, new_bfqq);
+
+ return bfqq;
+}
+
+static struct bfq_queue **bfq_async_queue_prio(struct bfq_data *bfqd,
+ struct bfq_group *bfqg,
+ int ioprio_class, int ioprio)
+{
+ switch (ioprio_class) {
+ case IOPRIO_CLASS_RT:
+ return &bfqg->async_bfqq[0][ioprio];
+ case IOPRIO_CLASS_BE:
+ return &bfqg->async_bfqq[1][ioprio];
+ case IOPRIO_CLASS_IDLE:
+ return &bfqg->async_idle_bfqq;
+ default:
+ BUG();
+ }
+}
+
+static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd,
+ struct bfq_group *bfqg, int is_sync,
+ struct io_context *ioc, gfp_t gfp_mask)
+{
+ const int ioprio = task_ioprio(ioc);
+ const int ioprio_class = task_ioprio_class(ioc);
+ struct bfq_queue **async_bfqq = NULL;
+ struct bfq_queue *bfqq = NULL;
+
+ if (!is_sync) {
+ async_bfqq = bfq_async_queue_prio(bfqd, bfqg, ioprio_class,
+ ioprio);
+ bfqq = *async_bfqq;
+ }
+
+ if (bfqq == NULL)
+ bfqq = bfq_find_alloc_queue(bfqd, bfqg, is_sync, ioc, gfp_mask);
+
+ /*
+ * Pin the queue now that it's allocated, scheduler exit will
+ * prune it.
+ */
+ if (!is_sync && *async_bfqq == NULL) {
+ atomic_inc(&bfqq->ref);
+ bfq_log_bfqq(bfqd, bfqq, "get_queue, bfqq not in async: %p, %d",
+ bfqq, atomic_read(&bfqq->ref));
+ *async_bfqq = bfqq;
+ }
+
+ atomic_inc(&bfqq->ref);
+ bfq_log_bfqq(bfqd, bfqq, "get_queue, at end: %p, %d", bfqq,
+ atomic_read(&bfqq->ref));
+ return bfqq;
+}
+
+static void bfq_update_io_thinktime(struct bfq_data *bfqd,
+ struct bfq_io_cq *bic)
+{
+ unsigned long elapsed = jiffies - bic->ttime.last_end_request;
+ unsigned long ttime = min(elapsed, 2UL * bfqd->bfq_slice_idle);
+
+ bic->ttime.ttime_samples = (7*bic->ttime.ttime_samples + 256) / 8;
+ bic->ttime.ttime_total = (7*bic->ttime.ttime_total + 256*ttime) / 8;
+ bic->ttime.ttime_mean = (bic->ttime.ttime_total + 128) /
+ bic->ttime.ttime_samples;
+}
+
+static void bfq_update_io_seektime(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ struct request *rq)
+{
+ sector_t sdist;
+ u64 total;
+
+ if (bfqq->last_request_pos < blk_rq_pos(rq))
+ sdist = blk_rq_pos(rq) - bfqq->last_request_pos;
+ else
+ sdist = bfqq->last_request_pos - blk_rq_pos(rq);
+
+ /*
+ * Don't allow the seek distance to get too large from the
+ * odd fragment, pagein, etc.
+ */
+ if (bfqq->seek_samples == 0) /* first request, not really a seek */
+ sdist = 0;
+ else if (bfqq->seek_samples <= 60) /* second & third seek */
+ sdist = min(sdist, (bfqq->seek_mean * 4) + 2*1024*1024);
+ else
+ sdist = min(sdist, (bfqq->seek_mean * 4) + 2*1024*64);
+
+ bfqq->seek_samples = (7*bfqq->seek_samples + 256) / 8;
+ bfqq->seek_total = (7*bfqq->seek_total + (u64)256*sdist) / 8;
+ total = bfqq->seek_total + (bfqq->seek_samples/2);
+ do_div(total, bfqq->seek_samples);
+ bfqq->seek_mean = (sector_t)total;
+
+ bfq_log_bfqq(bfqd, bfqq, "dist=%llu mean=%llu", (u64)sdist,
+ (u64)bfqq->seek_mean);
+}
+
+/*
+ * Disable idle window if the process thinks too long or seeks so much that
+ * it doesn't matter.
+ */
+static void bfq_update_idle_window(struct bfq_data *bfqd,
+ struct bfq_queue *bfqq,
+ struct bfq_io_cq *bic)
+{
+ int enable_idle;
+
+ /* Don't idle for async or idle io prio class. */
+ if (!bfq_bfqq_sync(bfqq) || bfq_class_idle(bfqq))
+ return;
+
+ /* Idle window just restored, statistics are meaningless. */
+ if (bfq_bfqq_just_split(bfqq))
+ return;
+
+ enable_idle = bfq_bfqq_idle_window(bfqq);
+
+ if (atomic_read(&bic->icq.ioc->nr_tasks) == 0 ||
+ bfqd->bfq_slice_idle == 0 ||
+ (bfqd->hw_tag && BFQQ_SEEKY(bfqq) &&
+ bfqq->wr_coeff == 1))
+ enable_idle = 0;
+ else if (bfq_sample_valid(bic->ttime.ttime_samples)) {
+ if (bic->ttime.ttime_mean > bfqd->bfq_slice_idle &&
+ bfqq->wr_coeff == 1)
+ enable_idle = 0;
+ else
+ enable_idle = 1;
+ }
+ bfq_log_bfqq(bfqd, bfqq, "update_idle_window: enable_idle %d",
+ enable_idle);
+
+ if (enable_idle)
+ bfq_mark_bfqq_idle_window(bfqq);
+ else
+ bfq_clear_bfqq_idle_window(bfqq);
+}
+
+/*
+ * Called when a new fs request (rq) is added to bfqq. Check if there's
+ * something we should do about it.
+ */
+static void bfq_rq_enqueued(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ struct request *rq)
+{
+ struct bfq_io_cq *bic = RQ_BIC(rq);
+
+ if (rq->cmd_flags & REQ_META)
+ bfqq->meta_pending++;
+
+ bfq_update_io_thinktime(bfqd, bic);
+ bfq_update_io_seektime(bfqd, bfqq, rq);
+ if (!BFQQ_SEEKY(bfqq) && bfq_bfqq_constantly_seeky(bfqq)) {
+ bfq_clear_bfqq_constantly_seeky(bfqq);
+ if (!blk_queue_nonrot(bfqd->queue)) {
+ BUG_ON(!bfqd->const_seeky_busy_in_flight_queues);
+ bfqd->const_seeky_busy_in_flight_queues--;
+ }
+ }
+ if (bfqq->entity.service > bfq_max_budget(bfqd) / 8 ||
+ !BFQQ_SEEKY(bfqq))
+ bfq_update_idle_window(bfqd, bfqq, bic);
+ bfq_clear_bfqq_just_split(bfqq);
+
+ bfq_log_bfqq(bfqd, bfqq,
+ "rq_enqueued: idle_window=%d (seeky %d, mean %llu)",
+ bfq_bfqq_idle_window(bfqq), BFQQ_SEEKY(bfqq),
+ (long long unsigned)bfqq->seek_mean);
+
+ bfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
+
+ if (bfqq == bfqd->in_service_queue && bfq_bfqq_wait_request(bfqq)) {
+ int small_req = bfqq->queued[rq_is_sync(rq)] == 1 &&
+ blk_rq_sectors(rq) < 32;
+ int budget_timeout = bfq_bfqq_budget_timeout(bfqq);
+
+ /*
+ * There is just this request queued: if the request
+ * is small and the queue is not to be expired, then
+ * just exit.
+ *
+ * In this way, if the disk is being idled to wait for
+ * a new request from the in-service queue, we avoid
+ * unplugging the device and committing the disk to serve
+ * just a small request. On the contrary, we wait for
+ * the block layer to decide when to unplug the device:
+ * hopefully, new requests will be merged to this one
+ * quickly, then the device will be unplugged and
+ * larger requests will be dispatched.
+ */
+ if (small_req && !budget_timeout)
+ return;
+
+ /*
+ * A large enough request arrived, or the queue is to
+ * be expired: in both cases disk idling is to be
+ * stopped, so clear wait_request flag and reset
+ * timer.
+ */
+ bfq_clear_bfqq_wait_request(bfqq);
+ del_timer(&bfqd->idle_slice_timer);
+
+ /*
+ * The queue is not empty, because a new request just
+ * arrived. Hence we can safely expire the queue, in
+ * case of budget timeout, without risking that the
+ * timestamps of the queue are not updated correctly.
+ * See [1] for more details.
+ */
+ if (budget_timeout)
+ bfq_bfqq_expire(bfqd, bfqq, 0, BFQ_BFQQ_BUDGET_TIMEOUT);
+
+ /*
+ * Let the request rip immediately, or let a new queue be
+ * selected if bfqq has just been expired.
+ */
+ __blk_run_queue(bfqd->queue);
+ }
+}
+
+static void bfq_insert_request(struct request_queue *q, struct request *rq)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+ struct bfq_queue *bfqq = RQ_BFQQ(rq), *new_bfqq;
+
+ assert_spin_locked(bfqd->queue->queue_lock);
+
+ /*
+ * An unplug may trigger a requeue of a request from the device
+ * driver: make sure we are in process context while trying to
+ * merge two bfq_queues.
+ */
+ if (!in_interrupt()) {
+ new_bfqq = bfq_setup_cooperator(bfqd, bfqq, rq, true);
+ if (new_bfqq != NULL) {
+ if (bic_to_bfqq(RQ_BIC(rq), 1) != bfqq)
+ new_bfqq = bic_to_bfqq(RQ_BIC(rq), 1);
+ /*
+ * Release the request's reference to the old bfqq
+ * and make sure one is taken to the shared queue.
+ */
+ new_bfqq->allocated[rq_data_dir(rq)]++;
+ bfqq->allocated[rq_data_dir(rq)]--;
+ atomic_inc(&new_bfqq->ref);
+ bfq_put_queue(bfqq);
+ if (bic_to_bfqq(RQ_BIC(rq), 1) == bfqq)
+ bfq_merge_bfqqs(bfqd, RQ_BIC(rq),
+ bfqq, new_bfqq);
+ rq->elv.priv[1] = new_bfqq;
+ bfqq = new_bfqq;
+ } else
+ bfq_bfqq_increase_failed_cooperations(bfqq);
+ }
+
+ bfq_init_prio_data(bfqq, RQ_BIC(rq)->icq.ioc);
+
+ bfq_add_request(rq);
+
+ /*
+ * Here a newly-created bfq_queue has already started a weight-raising
+ * period: clear raising_time_left to prevent bfq_bfqq_save_state()
+ * from assigning it a full weight-raising period. See the detailed
+ * comments about this field in bfq_init_icq().
+ */
+ if (bfqq->bic != NULL)
+ bfqq->bic->wr_time_left = 0;
+ rq_set_fifo_time(rq, jiffies + bfqd->bfq_fifo_expire[rq_is_sync(rq)]);
+ list_add_tail(&rq->queuelist, &bfqq->fifo);
+
+ bfq_rq_enqueued(bfqd, bfqq, rq);
+}
+
+static void bfq_update_hw_tag(struct bfq_data *bfqd)
+{
+ bfqd->max_rq_in_driver = max(bfqd->max_rq_in_driver,
+ bfqd->rq_in_driver);
+
+ if (bfqd->hw_tag == 1)
+ return;
+
+ /*
+ * This sample is valid if the number of outstanding requests
+ * is large enough to allow a queueing behavior. Note that the
+ * sum is not exact, as it's not taking into account deactivated
+ * requests.
+ */
+ if (bfqd->rq_in_driver + bfqd->queued < BFQ_HW_QUEUE_THRESHOLD)
+ return;
+
+ if (bfqd->hw_tag_samples++ < BFQ_HW_QUEUE_SAMPLES)
+ return;
+
+ bfqd->hw_tag = bfqd->max_rq_in_driver > BFQ_HW_QUEUE_THRESHOLD;
+ bfqd->max_rq_in_driver = 0;
+ bfqd->hw_tag_samples = 0;
+}
+
+static void bfq_completed_request(struct request_queue *q, struct request *rq)
+{
+ struct bfq_queue *bfqq = RQ_BFQQ(rq);
+ struct bfq_data *bfqd = bfqq->bfqd;
+ bool sync = bfq_bfqq_sync(bfqq);
+
+ bfq_log_bfqq(bfqd, bfqq, "completed one req with %u sects left (%d)",
+ blk_rq_sectors(rq), sync);
+
+ bfq_update_hw_tag(bfqd);
+
+ BUG_ON(!bfqd->rq_in_driver);
+ BUG_ON(!bfqq->dispatched);
+ bfqd->rq_in_driver--;
+ bfqq->dispatched--;
+
+ if (!bfqq->dispatched && !bfq_bfqq_busy(bfqq)) {
+ bfq_weights_tree_remove(bfqd, &bfqq->entity,
+ &bfqd->queue_weights_tree);
+ if (!blk_queue_nonrot(bfqd->queue)) {
+ BUG_ON(!bfqd->busy_in_flight_queues);
+ bfqd->busy_in_flight_queues--;
+ if (bfq_bfqq_constantly_seeky(bfqq)) {
+ BUG_ON(!bfqd->
+ const_seeky_busy_in_flight_queues);
+ bfqd->const_seeky_busy_in_flight_queues--;
+ }
+ }
+ }
+
+ if (sync) {
+ bfqd->sync_flight--;
+ RQ_BIC(rq)->ttime.last_end_request = jiffies;
+ }
+
+ /*
+ * If we are waiting to discover whether the request pattern of the
+ * task associated with the queue is actually isochronous, and
+ * both requisites for this condition to hold are satisfied, then
+ * compute soft_rt_next_start (see the comments to the function
+ * bfq_bfqq_softrt_next_start()).
+ */
+ if (bfq_bfqq_softrt_update(bfqq) && bfqq->dispatched == 0 &&
+ RB_EMPTY_ROOT(&bfqq->sort_list))
+ bfqq->soft_rt_next_start =
+ bfq_bfqq_softrt_next_start(bfqd, bfqq);
+
+ /*
+ * If this is the in-service queue, check if it needs to be expired,
+ * or if we want to idle in case it has no pending requests.
+ */
+ if (bfqd->in_service_queue == bfqq) {
+ if (bfq_bfqq_budget_new(bfqq))
+ bfq_set_budget_timeout(bfqd);
+
+ if (bfq_bfqq_must_idle(bfqq)) {
+ bfq_arm_slice_timer(bfqd);
+ goto out;
+ } else if (bfq_may_expire_for_budg_timeout(bfqq))
+ bfq_bfqq_expire(bfqd, bfqq, 0, BFQ_BFQQ_BUDGET_TIMEOUT);
+ else if (RB_EMPTY_ROOT(&bfqq->sort_list) &&
+ (bfqq->dispatched == 0 ||
+ !bfq_bfqq_must_not_expire(bfqq)))
+ bfq_bfqq_expire(bfqd, bfqq, 0,
+ BFQ_BFQQ_NO_MORE_REQUESTS);
+ }
+
+ if (!bfqd->rq_in_driver)
+ bfq_schedule_dispatch(bfqd);
+
+out:
+ return;
+}
+
+static inline int __bfq_may_queue(struct bfq_queue *bfqq)
+{
+ if (bfq_bfqq_wait_request(bfqq) && bfq_bfqq_must_alloc(bfqq)) {
+ bfq_clear_bfqq_must_alloc(bfqq);
+ return ELV_MQUEUE_MUST;
+ }
+
+ return ELV_MQUEUE_MAY;
+}
+
+static int bfq_may_queue(struct request_queue *q, int rw)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+ struct task_struct *tsk = current;
+ struct bfq_io_cq *bic;
+ struct bfq_queue *bfqq;
+
+ /*
+ * Don't force setup of a queue from here, as a call to may_queue
+ * does not necessarily imply that a request actually will be
+ * queued. So just lookup a possibly existing queue, or return
+ * 'may queue' if that fails.
+ */
+ bic = bfq_bic_lookup(bfqd, tsk->io_context);
+ if (bic == NULL)
+ return ELV_MQUEUE_MAY;
+
+ bfqq = bic_to_bfqq(bic, rw_is_sync(rw));
+ if (bfqq != NULL) {
+ bfq_init_prio_data(bfqq, bic->icq.ioc);
+
+ return __bfq_may_queue(bfqq);
+ }
+
+ return ELV_MQUEUE_MAY;
+}
+
+/*
+ * Queue lock held here.
+ */
+static void bfq_put_request(struct request *rq)
+{
+ struct bfq_queue *bfqq = RQ_BFQQ(rq);
+
+ if (bfqq != NULL) {
+ const int rw = rq_data_dir(rq);
+
+ BUG_ON(!bfqq->allocated[rw]);
+ bfqq->allocated[rw]--;
+
+ rq->elv.priv[0] = NULL;
+ rq->elv.priv[1] = NULL;
+
+ bfq_log_bfqq(bfqq->bfqd, bfqq, "put_request %p, %d",
+ bfqq, atomic_read(&bfqq->ref));
+ bfq_put_queue(bfqq);
+ }
+}
+
+/*
+ * Returns NULL if a new bfqq should be allocated, or the old bfqq if this
+ * was the last process referring to said bfqq.
+ */
+static struct bfq_queue *
+bfq_split_bfqq(struct bfq_io_cq *bic, struct bfq_queue *bfqq)
+{
+ bfq_log_bfqq(bfqq->bfqd, bfqq, "splitting queue");
+
+ put_io_context(bic->icq.ioc);
+
+ if (bfqq_process_refs(bfqq) == 1) {
+ bfqq->pid = current->pid;
+ bfq_clear_bfqq_coop(bfqq);
+ bfq_clear_bfqq_split_coop(bfqq);
+ return bfqq;
+ }
+
+ bic_set_bfqq(bic, NULL, 1);
+
+ bfq_put_cooperator(bfqq);
+
+ bfq_put_queue(bfqq);
+ return NULL;
+}
+
+/*
+ * Allocate bfq data structures associated with this request.
+ */
+static int bfq_set_request(struct request_queue *q, struct request *rq,
+ gfp_t gfp_mask)
+{
+ struct bfq_data *bfqd = q->elevator->elevator_data;
+ struct bfq_io_cq *bic = icq_to_bic(rq->elv.icq);
+ const int rw = rq_data_dir(rq);
+ const int is_sync = rq_is_sync(rq);
+ struct bfq_queue *bfqq;
+ struct bfq_group *bfqg;
+ unsigned long flags;
+ bool split = false;
+
+ /* handle changed prio notifications; cgroup change is handled separately */
+ if (unlikely(icq_get_changed(&bic->icq) & ICQ_IOPRIO_CHANGED))
+ bfq_changed_ioprio(bic->icq.ioc, bic);
+
+ might_sleep_if(gfp_mask & __GFP_WAIT);
+
+ spin_lock_irqsave(q->queue_lock, flags);
+
+ if (bic == NULL)
+ goto queue_fail;
+
+ bfqg = bfq_bic_update_cgroup(bic);
+
+new_queue:
+ bfqq = bic_to_bfqq(bic, is_sync);
+ if (bfqq == NULL || bfqq == &bfqd->oom_bfqq) {
+ bfqq = bfq_get_queue(bfqd, bfqg, is_sync, bic->icq.ioc, gfp_mask);
+ bic_set_bfqq(bic, bfqq, is_sync);
+ if (split && is_sync) {
+ if ((bic->was_in_burst_list && bfqd->large_burst) ||
+ bic->saved_in_large_burst)
+ bfq_mark_bfqq_in_large_burst(bfqq);
+ else {
+ bfq_clear_bfqq_in_large_burst(bfqq);
+ if (bic->was_in_burst_list)
+ hlist_add_head(&bfqq->burst_list_node,
+ &bfqd->burst_list);
+ }
+ }
+ } else {
+ /* If the queue was seeky for too long, break it apart. */
+ if (bfq_bfqq_coop(bfqq) && bfq_bfqq_split_coop(bfqq)) {
+ bfq_log_bfqq(bfqd, bfqq, "breaking apart bfqq");
+ bfqq = bfq_split_bfqq(bic, bfqq);
+ split = true;
+ if (!bfqq)
+ goto new_queue;
+ }
+ }
+
+ bfqq->allocated[rw]++;
+ atomic_inc(&bfqq->ref);
+ bfq_log_bfqq(bfqd, bfqq, "set_request: bfqq %p, %d", bfqq,
+ atomic_read(&bfqq->ref));
+
+ rq->elv.priv[0] = bic;
+ rq->elv.priv[1] = bfqq;
+
+ /*
+ * If a bfq_queue has only one process reference, it is owned
+ * by only one bfq_io_cq: we can set the bic field of the
+ * bfq_queue to the address of that structure. Also, if the
+ * queue has just been split, mark a flag so that the
+ * information is available to the other scheduler hooks.
+ */
+ if (likely(bfqq != &bfqd->oom_bfqq) && bfqq_process_refs(bfqq) == 1) {
+ bfqq->bic = bic;
+ if (split) {
+ bfq_mark_bfqq_just_split(bfqq);
+ /*
+ * If the queue has just been split from a shared
+ * queue, restore the idle window and the possible
+ * weight raising period.
+ */
+ bfq_bfqq_resume_state(bfqq, bic);
+ }
+ }
+
+ spin_unlock_irqrestore(q->queue_lock, flags);
+
+ return 0;
+
+queue_fail:
+ bfq_schedule_dispatch(bfqd);
+ spin_unlock_irqrestore(q->queue_lock, flags);
+
+ return 1;
+}
+
+static void bfq_kick_queue(struct work_struct *work)
+{
+ struct bfq_data *bfqd =
+ container_of(work, struct bfq_data, unplug_work);
+ struct request_queue *q = bfqd->queue;
+
+ spin_lock_irq(q->queue_lock);
+ __blk_run_queue(q);
+ spin_unlock_irq(q->queue_lock);
+}
+
+/*
+ * Handler of the expiration of the timer running if the in-service queue
+ * is idling inside its time slice.
+ */
+static void bfq_idle_slice_timer(unsigned long data)
+{
+ struct bfq_data *bfqd = (struct bfq_data *)data;
+ struct bfq_queue *bfqq;
+ unsigned long flags;
+ enum bfqq_expiration reason;
+
+ spin_lock_irqsave(bfqd->queue->queue_lock, flags);
+
+ bfqq = bfqd->in_service_queue;
+ /*
+ * Theoretical race here: the in-service queue can be NULL or
+ * different from the queue that was idling if the timer handler
+ * spins on the queue_lock and a new request arrives for the
+ * current queue and there is a full dispatch cycle that changes
+ * the in-service queue. This can hardly happen, but in the worst
+ * case we just expire a queue too early.
+ */
+ if (bfqq != NULL) {
+ bfq_log_bfqq(bfqd, bfqq, "slice_timer expired");
+ if (bfq_bfqq_budget_timeout(bfqq))
+ /*
+ * Also here the queue can be safely expired
+ * for budget timeout without wasting
+ * guarantees
+ */
+ reason = BFQ_BFQQ_BUDGET_TIMEOUT;
+ else if (bfqq->queued[0] == 0 && bfqq->queued[1] == 0)
+ /*
+ * The queue may not be empty upon timer expiration,
+ * because we may not disable the timer when the
+ * first request of the in-service queue arrives
+ * during disk idling.
+ */
+ reason = BFQ_BFQQ_TOO_IDLE;
+ else
+ goto schedule_dispatch;
+
+ bfq_bfqq_expire(bfqd, bfqq, 1, reason);
+ }
+
+schedule_dispatch:
+ bfq_schedule_dispatch(bfqd);
+
+ spin_unlock_irqrestore(bfqd->queue->queue_lock, flags);
+}
+
+static void bfq_shutdown_timer_wq(struct bfq_data *bfqd)
+{
+ del_timer_sync(&bfqd->idle_slice_timer);
+ cancel_work_sync(&bfqd->unplug_work);
+}
+
+static inline void __bfq_put_async_bfqq(struct bfq_data *bfqd,
+ struct bfq_queue **bfqq_ptr)
+{
+ struct bfq_group *root_group = bfqd->root_group;
+ struct bfq_queue *bfqq = *bfqq_ptr;
+
+ bfq_log(bfqd, "put_async_bfqq: %p", bfqq);
+ if (bfqq != NULL) {
+ bfq_bfqq_move(bfqd, bfqq, &bfqq->entity, root_group);
+ bfq_log_bfqq(bfqd, bfqq, "put_async_bfqq: putting %p, %d",
+ bfqq, atomic_read(&bfqq->ref));
+ bfq_put_queue(bfqq);
+ *bfqq_ptr = NULL;
+ }
+}
+
+/*
+ * Release all the bfqg references to its async queues. If we are
+ * deallocating the group these queues may still contain requests, so
+ * we reparent them to the root cgroup (i.e., the only one that will
+ * exist for sure until all the requests on a device are gone).
+ */
+static void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg)
+{
+ int i, j;
+
+ for (i = 0; i < 2; i++)
+ for (j = 0; j < IOPRIO_BE_NR; j++)
+ __bfq_put_async_bfqq(bfqd, &bfqg->async_bfqq[i][j]);
+
+ __bfq_put_async_bfqq(bfqd, &bfqg->async_idle_bfqq);
+}
+
+static void bfq_exit_queue(struct elevator_queue *e)
+{
+ struct bfq_data *bfqd = e->elevator_data;
+ struct request_queue *q = bfqd->queue;
+ struct bfq_queue *bfqq, *n;
+
+ bfq_shutdown_timer_wq(bfqd);
+
+ spin_lock_irq(q->queue_lock);
+
+ BUG_ON(bfqd->in_service_queue != NULL);
+ list_for_each_entry_safe(bfqq, n, &bfqd->idle_list, bfqq_list)
+ bfq_deactivate_bfqq(bfqd, bfqq, 0);
+
+ bfq_disconnect_groups(bfqd);
+ spin_unlock_irq(q->queue_lock);
+
+ bfq_shutdown_timer_wq(bfqd);
+
+ synchronize_rcu();
+
+ BUG_ON(timer_pending(&bfqd->idle_slice_timer));
+
+ bfq_free_root_group(bfqd);
+ kfree(bfqd);
+}
+
+static void *bfq_init_queue(struct request_queue *q)
+{
+ struct bfq_group *bfqg;
+ struct bfq_data *bfqd;
+
+ bfqd = kzalloc_node(sizeof(*bfqd), GFP_KERNEL, q->node);
+ if (bfqd == NULL)
+ return NULL;
+
+ /*
+ * Our fallback bfqq if bfq_find_alloc_queue() runs into OOM issues.
+ * Grab a permanent reference to it, so that the normal code flow
+ * will not attempt to free it.
+ */
+ bfq_init_bfqq(bfqd, &bfqd->oom_bfqq, 1, 0);
+ atomic_inc(&bfqd->oom_bfqq.ref);
+ bfqd->oom_bfqq.entity.new_ioprio = BFQ_DEFAULT_QUEUE_IOPRIO;
+ bfqd->oom_bfqq.entity.new_ioprio_class = IOPRIO_CLASS_BE;
+ /*
+ * Trigger weight initialization, according to ioprio, at the
+ * oom_bfqq's first activation. The oom_bfqq's ioprio and ioprio
+ * class won't be changed any more.
+ */
+ bfqd->oom_bfqq.entity.ioprio_changed = 1;
+
+ bfqd->queue = q;
+
+ bfqg = bfq_alloc_root_group(bfqd, q->node);
+ if (bfqg == NULL) {
+ kfree(bfqd);
+ return NULL;
+ }
+
+ bfqd->root_group = bfqg;
+ bfq_init_entity(&bfqd->oom_bfqq.entity, bfqd->root_group);
+#ifdef CONFIG_CGROUP_BFQIO
+ bfqd->active_numerous_groups = 0;
+#endif
+
+ init_timer(&bfqd->idle_slice_timer);
+ bfqd->idle_slice_timer.function = bfq_idle_slice_timer;
+ bfqd->idle_slice_timer.data = (unsigned long)bfqd;
+
+ bfqd->rq_pos_tree = RB_ROOT;
+ bfqd->queue_weights_tree = RB_ROOT;
+ bfqd->group_weights_tree = RB_ROOT;
+
+ INIT_WORK(&bfqd->unplug_work, bfq_kick_queue);
+
+ INIT_LIST_HEAD(&bfqd->active_list);
+ INIT_LIST_HEAD(&bfqd->idle_list);
+ INIT_HLIST_HEAD(&bfqd->burst_list);
+
+ bfqd->hw_tag = -1;
+
+ bfqd->bfq_max_budget = bfq_default_max_budget;
+
+ bfqd->bfq_quantum = bfq_quantum;
+ bfqd->bfq_fifo_expire[0] = bfq_fifo_expire[0];
+ bfqd->bfq_fifo_expire[1] = bfq_fifo_expire[1];
+ bfqd->bfq_back_max = bfq_back_max;
+ bfqd->bfq_back_penalty = bfq_back_penalty;
+ bfqd->bfq_slice_idle = bfq_slice_idle;
+ bfqd->bfq_class_idle_last_service = 0;
+ bfqd->bfq_max_budget_async_rq = bfq_max_budget_async_rq;
+ bfqd->bfq_timeout[BLK_RW_ASYNC] = bfq_timeout_async;
+ bfqd->bfq_timeout[BLK_RW_SYNC] = bfq_timeout_sync;
+
+ bfqd->bfq_coop_thresh = 2;
+ bfqd->bfq_failed_cooperations = 7000;
+ bfqd->bfq_requests_within_timer = 120;
+
+ bfqd->bfq_large_burst_thresh = 11;
+ bfqd->bfq_burst_interval = msecs_to_jiffies(500);
+
+ bfqd->low_latency = true;
+
+ bfqd->bfq_wr_coeff = 20;
+ bfqd->bfq_wr_rt_max_time = msecs_to_jiffies(300);
+ bfqd->bfq_wr_max_time = 0;
+ bfqd->bfq_wr_min_idle_time = msecs_to_jiffies(2000);
+ bfqd->bfq_wr_min_inter_arr_async = msecs_to_jiffies(500);
+ bfqd->bfq_wr_max_softrt_rate = 7000; /*
+ * Approximate rate required
+ * to playback or record a
+ * high-definition compressed
+ * video.
+ */
+ bfqd->wr_busy_queues = 0;
+ bfqd->busy_in_flight_queues = 0;
+ bfqd->const_seeky_busy_in_flight_queues = 0;
+
+ /*
+ * Begin by assuming, optimistically, that the device peak rate is
+ * equal to the highest reference rate.
+ */
+ bfqd->RT_prod = R_fast[blk_queue_nonrot(bfqd->queue)] *
+ T_fast[blk_queue_nonrot(bfqd->queue)];
+ bfqd->peak_rate = R_fast[blk_queue_nonrot(bfqd->queue)];
+ bfqd->device_speed = BFQ_BFQD_FAST;
+
+ return bfqd;
+}
+
+static void bfq_slab_kill(void)
+{
+ if (bfq_pool != NULL)
+ kmem_cache_destroy(bfq_pool);
+}
+
+static int __init bfq_slab_setup(void)
+{
+ bfq_pool = KMEM_CACHE(bfq_queue, 0);
+ if (bfq_pool == NULL)
+ return -ENOMEM;
+ return 0;
+}
+
+static ssize_t bfq_var_show(unsigned int var, char *page)
+{
+ return sprintf(page, "%d\n", var);
+}
+
+static ssize_t bfq_var_store(unsigned long *var, const char *page,
+ size_t count)
+{
+ unsigned long new_val;
+ int ret = kstrtoul(page, 10, &new_val);
+
+ if (ret == 0)
+ *var = new_val;
+
+ return count;
+}
+
+static ssize_t bfq_wr_max_time_show(struct elevator_queue *e, char *page)
+{
+ struct bfq_data *bfqd = e->elevator_data;
+ return sprintf(page, "%d\n", bfqd->bfq_wr_max_time > 0 ?
+ jiffies_to_msecs(bfqd->bfq_wr_max_time) :
+ jiffies_to_msecs(bfq_wr_duration(bfqd)));
+}
+
+static ssize_t bfq_weights_show(struct elevator_queue *e, char *page)
+{
+ struct bfq_queue *bfqq;
+ struct bfq_data *bfqd = e->elevator_data;
+ ssize_t num_char = 0;
+
+ num_char += sprintf(page + num_char, "Tot reqs queued %d\n\n",
+ bfqd->queued);
+
+ spin_lock_irq(bfqd->queue->queue_lock);
+
+ num_char += sprintf(page + num_char, "Active:\n");
+ list_for_each_entry(bfqq, &bfqd->active_list, bfqq_list) {
+ num_char += sprintf(page + num_char,
+ "pid%d: weight %hu, nr_queued %d %d, dur %d/%u\n",
+ bfqq->pid,
+ bfqq->entity.weight,
+ bfqq->queued[0],
+ bfqq->queued[1],
+ jiffies_to_msecs(jiffies - bfqq->last_wr_start_finish),
+ jiffies_to_msecs(bfqq->wr_cur_max_time));
+ }
+
+ num_char += sprintf(page + num_char, "Idle:\n");
+ list_for_each_entry(bfqq, &bfqd->idle_list, bfqq_list) {
+ num_char += sprintf(page + num_char,
+ "pid%d: weight %hu, dur %d/%u\n",
+ bfqq->pid,
+ bfqq->entity.weight,
+ jiffies_to_msecs(jiffies -
+ bfqq->last_wr_start_finish),
+ jiffies_to_msecs(bfqq->wr_cur_max_time));
+ }
+
+ spin_unlock_irq(bfqd->queue->queue_lock);
+
+ return num_char;
+}
+
+#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
+static ssize_t __FUNC(struct elevator_queue *e, char *page) \
+{ \
+ struct bfq_data *bfqd = e->elevator_data; \
+ unsigned int __data = __VAR; \
+ if (__CONV) \
+ __data = jiffies_to_msecs(__data); \
+ return bfq_var_show(__data, (page)); \
+}
+SHOW_FUNCTION(bfq_quantum_show, bfqd->bfq_quantum, 0);
+SHOW_FUNCTION(bfq_fifo_expire_sync_show, bfqd->bfq_fifo_expire[1], 1);
+SHOW_FUNCTION(bfq_fifo_expire_async_show, bfqd->bfq_fifo_expire[0], 1);
+SHOW_FUNCTION(bfq_back_seek_max_show, bfqd->bfq_back_max, 0);
+SHOW_FUNCTION(bfq_back_seek_penalty_show, bfqd->bfq_back_penalty, 0);
+SHOW_FUNCTION(bfq_slice_idle_show, bfqd->bfq_slice_idle, 1);
+SHOW_FUNCTION(bfq_max_budget_show, bfqd->bfq_user_max_budget, 0);
+SHOW_FUNCTION(bfq_max_budget_async_rq_show,
+ bfqd->bfq_max_budget_async_rq, 0);
+SHOW_FUNCTION(bfq_timeout_sync_show, bfqd->bfq_timeout[BLK_RW_SYNC], 1);
+SHOW_FUNCTION(bfq_timeout_async_show, bfqd->bfq_timeout[BLK_RW_ASYNC], 1);
+SHOW_FUNCTION(bfq_low_latency_show, bfqd->low_latency, 0);
+SHOW_FUNCTION(bfq_wr_coeff_show, bfqd->bfq_wr_coeff, 0);
+SHOW_FUNCTION(bfq_wr_rt_max_time_show, bfqd->bfq_wr_rt_max_time, 1);
+SHOW_FUNCTION(bfq_wr_min_idle_time_show, bfqd->bfq_wr_min_idle_time, 1);
+SHOW_FUNCTION(bfq_wr_min_inter_arr_async_show, bfqd->bfq_wr_min_inter_arr_async,
+ 1);
+SHOW_FUNCTION(bfq_wr_max_softrt_rate_show, bfqd->bfq_wr_max_softrt_rate, 0);
+#undef SHOW_FUNCTION
+
+#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
+static ssize_t \
+__FUNC(struct elevator_queue *e, const char *page, size_t count) \
+{ \
+ struct bfq_data *bfqd = e->elevator_data; \
+ unsigned long uninitialized_var(__data); \
+ int ret = bfq_var_store(&__data, (page), count); \
+ if (__data < (MIN)) \
+ __data = (MIN); \
+ else if (__data > (MAX)) \
+ __data = (MAX); \
+ if (__CONV) \
+ *(__PTR) = msecs_to_jiffies(__data); \
+ else \
+ *(__PTR) = __data; \
+ return ret; \
+}
+STORE_FUNCTION(bfq_quantum_store, &bfqd->bfq_quantum, 1, INT_MAX, 0);
+STORE_FUNCTION(bfq_fifo_expire_sync_store, &bfqd->bfq_fifo_expire[1], 1,
+ INT_MAX, 1);
+STORE_FUNCTION(bfq_fifo_expire_async_store, &bfqd->bfq_fifo_expire[0], 1,
+ INT_MAX, 1);
+STORE_FUNCTION(bfq_back_seek_max_store, &bfqd->bfq_back_max, 0, INT_MAX, 0);
+STORE_FUNCTION(bfq_back_seek_penalty_store, &bfqd->bfq_back_penalty, 1,
+ INT_MAX, 0);
+STORE_FUNCTION(bfq_slice_idle_store, &bfqd->bfq_slice_idle, 0, INT_MAX, 1);
+STORE_FUNCTION(bfq_max_budget_async_rq_store, &bfqd->bfq_max_budget_async_rq,
+ 1, INT_MAX, 0);
+STORE_FUNCTION(bfq_timeout_async_store, &bfqd->bfq_timeout[BLK_RW_ASYNC], 0,
+ INT_MAX, 1);
+STORE_FUNCTION(bfq_wr_coeff_store, &bfqd->bfq_wr_coeff, 1, INT_MAX, 0);
+STORE_FUNCTION(bfq_wr_max_time_store, &bfqd->bfq_wr_max_time, 0, INT_MAX, 1);
+STORE_FUNCTION(bfq_wr_rt_max_time_store, &bfqd->bfq_wr_rt_max_time, 0, INT_MAX,
+ 1);
+STORE_FUNCTION(bfq_wr_min_idle_time_store, &bfqd->bfq_wr_min_idle_time, 0,
+ INT_MAX, 1);
+STORE_FUNCTION(bfq_wr_min_inter_arr_async_store,
+ &bfqd->bfq_wr_min_inter_arr_async, 0, INT_MAX, 1);
+STORE_FUNCTION(bfq_wr_max_softrt_rate_store, &bfqd->bfq_wr_max_softrt_rate, 0,
+ INT_MAX, 0);
+#undef STORE_FUNCTION
+
+/* do nothing for the moment */
+static ssize_t bfq_weights_store(struct elevator_queue *e,
+ const char *page, size_t count)
+{
+ return count;
+}
+
+static inline unsigned long bfq_estimated_max_budget(struct bfq_data *bfqd)
+{
+ u64 timeout = jiffies_to_msecs(bfqd->bfq_timeout[BLK_RW_SYNC]);
+
+ if (bfqd->peak_rate_samples >= BFQ_PEAK_RATE_SAMPLES)
+ return bfq_calc_max_budget(bfqd->peak_rate, timeout);
+ else
+ return bfq_default_max_budget;
+}
+
+static ssize_t bfq_max_budget_store(struct elevator_queue *e,
+ const char *page, size_t count)
+{
+ struct bfq_data *bfqd = e->elevator_data;
+ unsigned long uninitialized_var(__data);
+ int ret = bfq_var_store(&__data, (page), count);
+
+ if (__data == 0)
+ bfqd->bfq_max_budget = bfq_estimated_max_budget(bfqd);
+ else {
+ if (__data > INT_MAX)
+ __data = INT_MAX;
+ bfqd->bfq_max_budget = __data;
+ }
+
+ bfqd->bfq_user_max_budget = __data;
+
+ return ret;
+}
+
+static ssize_t bfq_timeout_sync_store(struct elevator_queue *e,
+ const char *page, size_t count)
+{
+ struct bfq_data *bfqd = e->elevator_data;
+ unsigned long uninitialized_var(__data);
+ int ret = bfq_var_store(&__data, (page), count);
+
+ if (__data < 1)
+ __data = 1;
+ else if (__data > INT_MAX)
+ __data = INT_MAX;
+
+ bfqd->bfq_timeout[BLK_RW_SYNC] = msecs_to_jiffies(__data);
+ if (bfqd->bfq_user_max_budget == 0)
+ bfqd->bfq_max_budget = bfq_estimated_max_budget(bfqd);
+
+ return ret;
+}
+
+static ssize_t bfq_low_latency_store(struct elevator_queue *e,
+ const char *page, size_t count)
+{
+ struct bfq_data *bfqd = e->elevator_data;
+ unsigned long uninitialized_var(__data);
+ int ret = bfq_var_store(&__data, (page), count);
+
+ if (__data > 1)
+ __data = 1;
+ if (__data == 0 && bfqd->low_latency != 0)
+ bfq_end_wr(bfqd);
+ bfqd->low_latency = __data;
+
+ return ret;
+}
+
+#define BFQ_ATTR(name) \
+ __ATTR(name, S_IRUGO|S_IWUSR, bfq_##name##_show, bfq_##name##_store)
+
+static struct elv_fs_entry bfq_attrs[] = {
+ BFQ_ATTR(quantum),
+ BFQ_ATTR(fifo_expire_sync),
+ BFQ_ATTR(fifo_expire_async),
+ BFQ_ATTR(back_seek_max),
+ BFQ_ATTR(back_seek_penalty),
+ BFQ_ATTR(slice_idle),
+ BFQ_ATTR(max_budget),
+ BFQ_ATTR(max_budget_async_rq),
+ BFQ_ATTR(timeout_sync),
+ BFQ_ATTR(timeout_async),
+ BFQ_ATTR(low_latency),
+ BFQ_ATTR(wr_coeff),
+ BFQ_ATTR(wr_max_time),
+ BFQ_ATTR(wr_rt_max_time),
+ BFQ_ATTR(wr_min_idle_time),
+ BFQ_ATTR(wr_min_inter_arr_async),
+ BFQ_ATTR(wr_max_softrt_rate),
+ BFQ_ATTR(weights),
+ __ATTR_NULL
+};
+
+static struct elevator_type iosched_bfq = {
+ .ops = {
+ .elevator_merge_fn = bfq_merge,
+ .elevator_merged_fn = bfq_merged_request,
+ .elevator_merge_req_fn = bfq_merged_requests,
+ .elevator_allow_merge_fn = bfq_allow_merge,
+ .elevator_dispatch_fn = bfq_dispatch_requests,
+ .elevator_add_req_fn = bfq_insert_request,
+ .elevator_activate_req_fn = bfq_activate_request,
+ .elevator_deactivate_req_fn = bfq_deactivate_request,
+ .elevator_completed_req_fn = bfq_completed_request,
+ .elevator_former_req_fn = elv_rb_former_request,
+ .elevator_latter_req_fn = elv_rb_latter_request,
+ .elevator_init_icq_fn = bfq_init_icq,
+ .elevator_exit_icq_fn = bfq_exit_icq,
+ .elevator_set_req_fn = bfq_set_request,
+ .elevator_put_req_fn = bfq_put_request,
+ .elevator_may_queue_fn = bfq_may_queue,
+ .elevator_init_fn = bfq_init_queue,
+ .elevator_exit_fn = bfq_exit_queue,
+ },
+ .icq_size = sizeof(struct bfq_io_cq),
+ .icq_align = __alignof__(struct bfq_io_cq),
+ .elevator_attrs = bfq_attrs,
+ .elevator_name = "bfq",
+ .elevator_owner = THIS_MODULE,
+};
+
+static int __init bfq_init(void)
+{
+ /*
+ * Can be 0 on HZ < 1000 setups.
+ */
+ if (bfq_slice_idle == 0)
+ bfq_slice_idle = 1;
+
+ if (bfq_timeout_async == 0)
+ bfq_timeout_async = 1;
+
+ if (bfq_slab_setup())
+ return -ENOMEM;
+
+ /*
+ * Times to load large popular applications for the typical systems
+ * installed on the reference devices (see the comments before the
+ * definitions of the two arrays).
+ */
+ T_slow[0] = msecs_to_jiffies(2600);
+ T_slow[1] = msecs_to_jiffies(1000);
+ T_fast[0] = msecs_to_jiffies(5500);
+ T_fast[1] = msecs_to_jiffies(2000);
+
+ /*
+ * Thresholds that determine the switch between speed classes (see
+ * the comments before the definition of the array).
+ */
+ device_speed_thresh[0] = (R_fast[0] + R_slow[0]) / 2;
+ device_speed_thresh[1] = (R_fast[1] + R_slow[1]) / 2;
+
+ elv_register(&iosched_bfq);
+ pr_info("BFQ I/O-scheduler version: v7r7");
+
+ return 0;
+}
+
+static void __exit bfq_exit(void)
+{
+ elv_unregister(&iosched_bfq);
+ bfq_slab_kill();
+}
+
+module_init(bfq_init);
+module_exit(bfq_exit);
+
+MODULE_AUTHOR("Fabio Checconi, Paolo Valente");
+MODULE_LICENSE("GPL");
diff --git a/block/bfq-sched.c b/block/bfq-sched.c
new file mode 100644
index 0000000..6764a7e
--- /dev/null
+++ b/block/bfq-sched.c
@@ -0,0 +1,1186 @@
+/*
+ * BFQ: Hierarchical B-WF2Q+ scheduler.
+ *
+ * Based on ideas and code from CFQ:
+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
+ *
+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
+ * Paolo Valente <paolo.valente@unimore.it>
+ *
+ * Copyright (C) 2010 Paolo Valente <paolo.valente@unimore.it>
+ */
+
+#ifdef CONFIG_CGROUP_BFQIO
+#define for_each_entity(entity) \
+ for (; entity != NULL; entity = entity->parent)
+
+#define for_each_entity_safe(entity, parent) \
+ for (; entity && ({ parent = entity->parent; 1; }); entity = parent)
+
+static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd,
+ int extract,
+ struct bfq_data *bfqd);
+
+static inline void bfq_update_budget(struct bfq_entity *next_in_service)
+{
+ struct bfq_entity *bfqg_entity;
+ struct bfq_group *bfqg;
+ struct bfq_sched_data *group_sd;
+
+ BUG_ON(next_in_service == NULL);
+
+ group_sd = next_in_service->sched_data;
+
+ bfqg = container_of(group_sd, struct bfq_group, sched_data);
+ /*
+ * bfq_group's my_entity field is not NULL only if the group
+ * is not the root group. We must not touch the root entity
+ * as it must never become an in-service entity.
+ */
+ bfqg_entity = bfqg->my_entity;
+ if (bfqg_entity != NULL)
+ bfqg_entity->budget = next_in_service->budget;
+}
+
+static int bfq_update_next_in_service(struct bfq_sched_data *sd)
+{
+ struct bfq_entity *next_in_service;
+
+ if (sd->in_service_entity != NULL)
+ /* will update/requeue at the end of service */
+ return 0;
+
+ /*
+ * NOTE: this can be improved in many ways, such as returning
+ * 1 (and thus propagating upwards the update) only when the
+ * budget changes, or caching the bfqq that will be scheduled
+ * next from this subtree. By now we worry more about
+ * correctness than about performance...
+ */
+ next_in_service = bfq_lookup_next_entity(sd, 0, NULL);
+ sd->next_in_service = next_in_service;
+
+ if (next_in_service != NULL)
+ bfq_update_budget(next_in_service);
+
+ return 1;
+}
+
+static inline void bfq_check_next_in_service(struct bfq_sched_data *sd,
+ struct bfq_entity *entity)
+{
+ BUG_ON(sd->next_in_service != entity);
+}
+#else
+#define for_each_entity(entity) \
+ for (; entity != NULL; entity = NULL)
+
+#define for_each_entity_safe(entity, parent) \
+ for (parent = NULL; entity != NULL; entity = parent)
+
+static inline int bfq_update_next_in_service(struct bfq_sched_data *sd)
+{
+ return 0;
+}
+
+static inline void bfq_check_next_in_service(struct bfq_sched_data *sd,
+ struct bfq_entity *entity)
+{
+}
+
+static inline void bfq_update_budget(struct bfq_entity *next_in_service)
+{
+}
+#endif
+
+/*
+ * Shift for timestamp calculations. This actually limits the maximum
+ * service allowed in one timestamp delta (small shift values increase it),
+ * the maximum total weight that can be used for the queues in the system
+ * (big shift values increase it), and the period of virtual time
+ * wraparounds.
+ */
+#define WFQ_SERVICE_SHIFT 22
+
+/**
+ * bfq_gt - compare two timestamps.
+ * @a: first ts.
+ * @b: second ts.
+ *
+ * Return @a > @b, dealing with wrapping correctly.
+ */
+static inline int bfq_gt(u64 a, u64 b)
+{
+ return (s64)(a - b) > 0;
+}
+
+static inline struct bfq_queue *bfq_entity_to_bfqq(struct bfq_entity *entity)
+{
+ struct bfq_queue *bfqq = NULL;
+
+ BUG_ON(entity == NULL);
+
+ if (entity->my_sched_data == NULL)
+ bfqq = container_of(entity, struct bfq_queue, entity);
+
+ return bfqq;
+}
+
+
+/**
+ * bfq_delta - map service into the virtual time domain.
+ * @service: amount of service.
+ * @weight: scale factor (weight of an entity or weight sum).
+ */
+static inline u64 bfq_delta(unsigned long service,
+ unsigned long weight)
+{
+ u64 d = (u64)service << WFQ_SERVICE_SHIFT;
+
+ do_div(d, weight);
+ return d;
+}
+
+/**
+ * bfq_calc_finish - assign the finish time to an entity.
+ * @entity: the entity to act upon.
+ * @service: the service to be charged to the entity.
+ */
+static inline void bfq_calc_finish(struct bfq_entity *entity,
+ unsigned long service)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+
+ BUG_ON(entity->weight == 0);
+
+ entity->finish = entity->start +
+ bfq_delta(service, entity->weight);
+
+ if (bfqq != NULL) {
+ bfq_log_bfqq(bfqq->bfqd, bfqq,
+ "calc_finish: serv %lu, w %d",
+ service, entity->weight);
+ bfq_log_bfqq(bfqq->bfqd, bfqq,
+ "calc_finish: start %llu, finish %llu, delta %llu",
+ entity->start, entity->finish,
+ bfq_delta(service, entity->weight));
+ }
+}
+
+/**
+ * bfq_entity_of - get an entity from a node.
+ * @node: the node field of the entity.
+ *
+ * Convert a node pointer to the relative entity. This is used only
+ * to simplify the logic of some functions and not as the generic
+ * conversion mechanism because, e.g., in the tree walking functions,
+ * the check for a %NULL value would be redundant.
+ */
+static inline struct bfq_entity *bfq_entity_of(struct rb_node *node)
+{
+ struct bfq_entity *entity = NULL;
+
+ if (node != NULL)
+ entity = rb_entry(node, struct bfq_entity, rb_node);
+
+ return entity;
+}
+
+/**
+ * bfq_extract - remove an entity from a tree.
+ * @root: the tree root.
+ * @entity: the entity to remove.
+ */
+static inline void bfq_extract(struct rb_root *root,
+ struct bfq_entity *entity)
+{
+ BUG_ON(entity->tree != root);
+
+ entity->tree = NULL;
+ rb_erase(&entity->rb_node, root);
+}
+
+/**
+ * bfq_idle_extract - extract an entity from the idle tree.
+ * @st: the service tree of the owning @entity.
+ * @entity: the entity being removed.
+ */
+static void bfq_idle_extract(struct bfq_service_tree *st,
+ struct bfq_entity *entity)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+ struct rb_node *next;
+
+ BUG_ON(entity->tree != &st->idle);
+
+ if (entity == st->first_idle) {
+ next = rb_next(&entity->rb_node);
+ st->first_idle = bfq_entity_of(next);
+ }
+
+ if (entity == st->last_idle) {
+ next = rb_prev(&entity->rb_node);
+ st->last_idle = bfq_entity_of(next);
+ }
+
+ bfq_extract(&st->idle, entity);
+
+ if (bfqq != NULL)
+ list_del(&bfqq->bfqq_list);
+}
+
+/**
+ * bfq_insert - generic tree insertion.
+ * @root: tree root.
+ * @entity: entity to insert.
+ *
+ * This is used for the idle and the active tree, since they are both
+ * ordered by finish time.
+ */
+static void bfq_insert(struct rb_root *root, struct bfq_entity *entity)
+{
+ struct bfq_entity *entry;
+ struct rb_node **node = &root->rb_node;
+ struct rb_node *parent = NULL;
+
+ BUG_ON(entity->tree != NULL);
+
+ while (*node != NULL) {
+ parent = *node;
+ entry = rb_entry(parent, struct bfq_entity, rb_node);
+
+ if (bfq_gt(entry->finish, entity->finish))
+ node = &parent->rb_left;
+ else
+ node = &parent->rb_right;
+ }
+
+ rb_link_node(&entity->rb_node, parent, node);
+ rb_insert_color(&entity->rb_node, root);
+
+ entity->tree = root;
+}
+
+/**
+ * bfq_update_min - update the min_start field of a entity.
+ * @entity: the entity to update.
+ * @node: one of its children.
+ *
+ * This function is called when @entity may store an invalid value for
+ * min_start due to updates to the active tree. The function assumes
+ * that the subtree rooted at @node (which may be its left or its right
+ * child) has a valid min_start value.
+ */
+static inline void bfq_update_min(struct bfq_entity *entity,
+ struct rb_node *node)
+{
+ struct bfq_entity *child;
+
+ if (node != NULL) {
+ child = rb_entry(node, struct bfq_entity, rb_node);
+ if (bfq_gt(entity->min_start, child->min_start))
+ entity->min_start = child->min_start;
+ }
+}
+
+/**
+ * bfq_update_active_node - recalculate min_start.
+ * @node: the node to update.
+ *
+ * @node may have changed position or one of its children may have moved,
+ * this function updates its min_start value. The left and right subtrees
+ * are assumed to hold a correct min_start value.
+ */
+static inline void bfq_update_active_node(struct rb_node *node)
+{
+ struct bfq_entity *entity = rb_entry(node, struct bfq_entity, rb_node);
+
+ entity->min_start = entity->start;
+ bfq_update_min(entity, node->rb_right);
+ bfq_update_min(entity, node->rb_left);
+}
+
+/**
+ * bfq_update_active_tree - update min_start for the whole active tree.
+ * @node: the starting node.
+ *
+ * @node must be the deepest modified node after an update. This function
+ * updates its min_start using the values held by its children, assuming
+ * that they did not change, and then updates all the nodes that may have
+ * changed in the path to the root. The only nodes that may have changed
+ * are the ones in the path or their siblings.
+ */
+static void bfq_update_active_tree(struct rb_node *node)
+{
+ struct rb_node *parent;
+
+up:
+ bfq_update_active_node(node);
+
+ parent = rb_parent(node);
+ if (parent == NULL)
+ return;
+
+ if (node == parent->rb_left && parent->rb_right != NULL)
+ bfq_update_active_node(parent->rb_right);
+ else if (parent->rb_left != NULL)
+ bfq_update_active_node(parent->rb_left);
+
+ node = parent;
+ goto up;
+}
+
+static void bfq_weights_tree_add(struct bfq_data *bfqd,
+ struct bfq_entity *entity,
+ struct rb_root *root);
+
+static void bfq_weights_tree_remove(struct bfq_data *bfqd,
+ struct bfq_entity *entity,
+ struct rb_root *root);
+
+
+/**
+ * bfq_active_insert - insert an entity in the active tree of its
+ * group/device.
+ * @st: the service tree of the entity.
+ * @entity: the entity being inserted.
+ *
+ * The active tree is ordered by finish time, but an extra key is kept
+ * per each node, containing the minimum value for the start times of
+ * its children (and the node itself), so it's possible to search for
+ * the eligible node with the lowest finish time in logarithmic time.
+ */
+static void bfq_active_insert(struct bfq_service_tree *st,
+ struct bfq_entity *entity)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+ struct rb_node *node = &entity->rb_node;
+#ifdef CONFIG_CGROUP_BFQIO
+ struct bfq_sched_data *sd = NULL;
+ struct bfq_group *bfqg = NULL;
+ struct bfq_data *bfqd = NULL;
+#endif
+
+ bfq_insert(&st->active, entity);
+
+ if (node->rb_left != NULL)
+ node = node->rb_left;
+ else if (node->rb_right != NULL)
+ node = node->rb_right;
+
+ bfq_update_active_tree(node);
+
+#ifdef CONFIG_CGROUP_BFQIO
+ sd = entity->sched_data;
+ bfqg = container_of(sd, struct bfq_group, sched_data);
+ BUG_ON(!bfqg);
+ bfqd = (struct bfq_data *)bfqg->bfqd;
+#endif
+ if (bfqq != NULL)
+ list_add(&bfqq->bfqq_list, &bfqq->bfqd->active_list);
+#ifdef CONFIG_CGROUP_BFQIO
+ else { /* bfq_group */
+ BUG_ON(!bfqd);
+ bfq_weights_tree_add(bfqd, entity, &bfqd->group_weights_tree);
+ }
+ if (bfqg != bfqd->root_group) {
+ BUG_ON(!bfqg);
+ BUG_ON(!bfqd);
+ bfqg->active_entities++;
+ if (bfqg->active_entities == 2)
+ bfqd->active_numerous_groups++;
+ }
+#endif
+}
+
+/**
+ * bfq_ioprio_to_weight - calc a weight from an ioprio.
+ * @ioprio: the ioprio value to convert.
+ */
+static inline unsigned short bfq_ioprio_to_weight(int ioprio)
+{
+ BUG_ON(ioprio < 0 || ioprio >= IOPRIO_BE_NR);
+ return IOPRIO_BE_NR - ioprio;
+}
+
+/**
+ * bfq_weight_to_ioprio - calc an ioprio from a weight.
+ * @weight: the weight value to convert.
+ *
+ * To preserve as mush as possible the old only-ioprio user interface,
+ * 0 is used as an escape ioprio value for weights (numerically) equal or
+ * larger than IOPRIO_BE_NR
+ */
+static inline unsigned short bfq_weight_to_ioprio(int weight)
+{
+ BUG_ON(weight < BFQ_MIN_WEIGHT || weight > BFQ_MAX_WEIGHT);
+ return IOPRIO_BE_NR - weight < 0 ? 0 : IOPRIO_BE_NR - weight;
+}
+
+static inline void bfq_get_entity(struct bfq_entity *entity)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+
+ if (bfqq != NULL) {
+ atomic_inc(&bfqq->ref);
+ bfq_log_bfqq(bfqq->bfqd, bfqq, "get_entity: %p %d",
+ bfqq, atomic_read(&bfqq->ref));
+ }
+}
+
+/**
+ * bfq_find_deepest - find the deepest node that an extraction can modify.
+ * @node: the node being removed.
+ *
+ * Do the first step of an extraction in an rb tree, looking for the
+ * node that will replace @node, and returning the deepest node that
+ * the following modifications to the tree can touch. If @node is the
+ * last node in the tree return %NULL.
+ */
+static struct rb_node *bfq_find_deepest(struct rb_node *node)
+{
+ struct rb_node *deepest;
+
+ if (node->rb_right == NULL && node->rb_left == NULL)
+ deepest = rb_parent(node);
+ else if (node->rb_right == NULL)
+ deepest = node->rb_left;
+ else if (node->rb_left == NULL)
+ deepest = node->rb_right;
+ else {
+ deepest = rb_next(node);
+ if (deepest->rb_right != NULL)
+ deepest = deepest->rb_right;
+ else if (rb_parent(deepest) != node)
+ deepest = rb_parent(deepest);
+ }
+
+ return deepest;
+}
+
+/**
+ * bfq_active_extract - remove an entity from the active tree.
+ * @st: the service_tree containing the tree.
+ * @entity: the entity being removed.
+ */
+static void bfq_active_extract(struct bfq_service_tree *st,
+ struct bfq_entity *entity)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+ struct rb_node *node;
+#ifdef CONFIG_CGROUP_BFQIO
+ struct bfq_sched_data *sd = NULL;
+ struct bfq_group *bfqg = NULL;
+ struct bfq_data *bfqd = NULL;
+#endif
+
+ node = bfq_find_deepest(&entity->rb_node);
+ bfq_extract(&st->active, entity);
+
+ if (node != NULL)
+ bfq_update_active_tree(node);
+
+#ifdef CONFIG_CGROUP_BFQIO
+ sd = entity->sched_data;
+ bfqg = container_of(sd, struct bfq_group, sched_data);
+ BUG_ON(!bfqg);
+ bfqd = (struct bfq_data *)bfqg->bfqd;
+#endif
+ if (bfqq != NULL)
+ list_del(&bfqq->bfqq_list);
+#ifdef CONFIG_CGROUP_BFQIO
+ else { /* bfq_group */
+ BUG_ON(!bfqd);
+ bfq_weights_tree_remove(bfqd, entity,
+ &bfqd->group_weights_tree);
+ }
+ if (bfqg != bfqd->root_group) {
+ BUG_ON(!bfqg);
+ BUG_ON(!bfqd);
+ BUG_ON(!bfqg->active_entities);
+ bfqg->active_entities--;
+ if (bfqg->active_entities == 1) {
+ BUG_ON(!bfqd->active_numerous_groups);
+ bfqd->active_numerous_groups--;
+ }
+ }
+#endif
+}
+
+/**
+ * bfq_idle_insert - insert an entity into the idle tree.
+ * @st: the service tree containing the tree.
+ * @entity: the entity to insert.
+ */
+static void bfq_idle_insert(struct bfq_service_tree *st,
+ struct bfq_entity *entity)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+ struct bfq_entity *first_idle = st->first_idle;
+ struct bfq_entity *last_idle = st->last_idle;
+
+ if (first_idle == NULL || bfq_gt(first_idle->finish, entity->finish))
+ st->first_idle = entity;
+ if (last_idle == NULL || bfq_gt(entity->finish, last_idle->finish))
+ st->last_idle = entity;
+
+ bfq_insert(&st->idle, entity);
+
+ if (bfqq != NULL)
+ list_add(&bfqq->bfqq_list, &bfqq->bfqd->idle_list);
+}
+
+/**
+ * bfq_forget_entity - remove an entity from the wfq trees.
+ * @st: the service tree.
+ * @entity: the entity being removed.
+ *
+ * Update the device status and forget everything about @entity, putting
+ * the device reference to it, if it is a queue. Entities belonging to
+ * groups are not refcounted.
+ */
+static void bfq_forget_entity(struct bfq_service_tree *st,
+ struct bfq_entity *entity)
+{
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+ struct bfq_sched_data *sd;
+
+ BUG_ON(!entity->on_st);
+
+ entity->on_st = 0;
+ st->wsum -= entity->weight;
+ if (bfqq != NULL) {
+ sd = entity->sched_data;
+ bfq_log_bfqq(bfqq->bfqd, bfqq, "forget_entity: %p %d",
+ bfqq, atomic_read(&bfqq->ref));
+ bfq_put_queue(bfqq);
+ }
+}
+
+/**
+ * bfq_put_idle_entity - release the idle tree ref of an entity.
+ * @st: service tree for the entity.
+ * @entity: the entity being released.
+ */
+static void bfq_put_idle_entity(struct bfq_service_tree *st,
+ struct bfq_entity *entity)
+{
+ bfq_idle_extract(st, entity);
+ bfq_forget_entity(st, entity);
+}
+
+/**
+ * bfq_forget_idle - update the idle tree if necessary.
+ * @st: the service tree to act upon.
+ *
+ * To preserve the global O(log N) complexity we only remove one entry here;
+ * as the idle tree will not grow indefinitely this can be done safely.
+ */
+static void bfq_forget_idle(struct bfq_service_tree *st)
+{
+ struct bfq_entity *first_idle = st->first_idle;
+ struct bfq_entity *last_idle = st->last_idle;
+
+ if (RB_EMPTY_ROOT(&st->active) && last_idle != NULL &&
+ !bfq_gt(last_idle->finish, st->vtime)) {
+ /*
+ * Forget the whole idle tree, increasing the vtime past
+ * the last finish time of idle entities.
+ */
+ st->vtime = last_idle->finish;
+ }
+
+ if (first_idle != NULL && !bfq_gt(first_idle->finish, st->vtime))
+ bfq_put_idle_entity(st, first_idle);
+}
+
+static struct bfq_service_tree *
+__bfq_entity_update_weight_prio(struct bfq_service_tree *old_st,
+ struct bfq_entity *entity)
+{
+ struct bfq_service_tree *new_st = old_st;
+
+ if (entity->ioprio_changed) {
+ struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
+ unsigned short prev_weight, new_weight;
+ struct bfq_data *bfqd = NULL;
+ struct rb_root *root;
+#ifdef CONFIG_CGROUP_BFQIO
+ struct bfq_sched_data *sd;
+ struct bfq_group *bfqg;
+#endif
+
+ if (bfqq != NULL)
+ bfqd = bfqq->bfqd;
+#ifdef CONFIG_CGROUP_BFQIO
+ else {
+ sd = entity->my_sched_data;
+ bfqg = container_of(sd, struct bfq_group, sched_data);
+ BUG_ON(!bfqg);
+ bfqd = (struct bfq_data *)bfqg->bfqd;
+ BUG_ON(!bfqd);
+ }
+#endif
+
+ BUG_ON(old_st->wsum < entity->weight);
+ old_st->wsum -= entity->weight;
+
+ if (entity->new_weight != entity->orig_weight) {
+ if (entity->new_weight < BFQ_MIN_WEIGHT ||
+ entity->new_weight > BFQ_MAX_WEIGHT) {
+ printk(KERN_CRIT "update_weight_prio: "
+ "new_weight %d\n",
+ entity->new_weight);
+ BUG();
+ }
+ entity->orig_weight = entity->new_weight;
+ entity->ioprio =
+ bfq_weight_to_ioprio(entity->orig_weight);
+ } else if (entity->new_ioprio != entity->ioprio) {
+ entity->ioprio = entity->new_ioprio;
+ entity->orig_weight =
+ bfq_ioprio_to_weight(entity->ioprio);
+ } else
+ entity->new_weight = entity->orig_weight =
+ bfq_ioprio_to_weight(entity->ioprio);
+
+ entity->ioprio_class = entity->new_ioprio_class;
+ entity->ioprio_changed = 0;
+
+ /*
+ * NOTE: here we may be changing the weight too early,
+ * this will cause unfairness. The correct approach
+ * would have required additional complexity to defer
+ * weight changes to the proper time instants (i.e.,
+ * when entity->finish <= old_st->vtime).
+ */
+ new_st = bfq_entity_service_tree(entity);
+
+ prev_weight = entity->weight;
+ new_weight = entity->orig_weight *
+ (bfqq != NULL ? bfqq->wr_coeff : 1);
+ /*
+ * If the weight of the entity changes, remove the entity
+ * from its old weight counter (if there is a counter
+ * associated with the entity), and add it to the counter
+ * associated with its new weight.
+ */
+ if (prev_weight != new_weight) {
+ root = bfqq ? &bfqd->queue_weights_tree :
+ &bfqd->group_weights_tree;
+ bfq_weights_tree_remove(bfqd, entity, root);
+ }
+ entity->weight = new_weight;
+ /*
+ * Add the entity to its weights tree only if it is
+ * not associated with a weight-raised queue.
+ */
+ if (prev_weight != new_weight &&
+ (bfqq ? bfqq->wr_coeff == 1 : 1))
+ /* If we get here, root has been initialized. */
+ bfq_weights_tree_add(bfqd, entity, root);
+
+ new_st->wsum += entity->weight;
+
+ if (new_st != old_st)
+ entity->start = new_st->vtime;
+ }
+
+ return new_st;
+}
+
+/**
+ * bfq_bfqq_served - update the scheduler status after selection for
+ * service.
+ * @bfqq: the queue being served.
+ * @served: bytes to transfer.
+ *
+ * NOTE: this can be optimized, as the timestamps of upper level entities
+ * are synchronized every time a new bfqq is selected for service. By now,
+ * we keep it to better check consistency.
+ */
+static void bfq_bfqq_served(struct bfq_queue *bfqq, unsigned long served)
+{
+ struct bfq_entity *entity = &bfqq->entity;
+ struct bfq_service_tree *st;
+
+ for_each_entity(entity) {
+ st = bfq_entity_service_tree(entity);
+
+ entity->service += served;
+ BUG_ON(entity->service > entity->budget);
+ BUG_ON(st->wsum == 0);
+
+ st->vtime += bfq_delta(served, st->wsum);
+ bfq_forget_idle(st);
+ }
+ bfq_log_bfqq(bfqq->bfqd, bfqq, "bfqq_served %lu secs", served);
+}
+
+/**
+ * bfq_bfqq_charge_full_budget - set the service to the entity budget.
+ * @bfqq: the queue that needs a service update.
+ *
+ * When it's not possible to be fair in the service domain, because
+ * a queue is not consuming its budget fast enough (the meaning of
+ * fast depends on the timeout parameter), we charge it a full
+ * budget. In this way we should obtain a sort of time-domain
+ * fairness among all the seeky/slow queues.
+ */
+static inline void bfq_bfqq_charge_full_budget(struct bfq_queue *bfqq)
+{
+ struct bfq_entity *entity = &bfqq->entity;
+
+ bfq_log_bfqq(bfqq->bfqd, bfqq, "charge_full_budget");
+
+ bfq_bfqq_served(bfqq, entity->budget - entity->service);
+}
+
+/**
+ * __bfq_activate_entity - activate an entity.
+ * @entity: the entity being activated.
+ *
+ * Called whenever an entity is activated, i.e., it is not active and one
+ * of its children receives a new request, or has to be reactivated due to
+ * budget exhaustion. It uses the current budget of the entity (and the
+ * service received if @entity is active) of the queue to calculate its
+ * timestamps.
+ */
+static void __bfq_activate_entity(struct bfq_entity *entity)
+{
+ struct bfq_sched_data *sd = entity->sched_data;
+ struct bfq_service_tree *st = bfq_entity_service_tree(entity);
+
+ if (entity == sd->in_service_entity) {
+ BUG_ON(entity->tree != NULL);
+ /*
+ * If we are requeueing the current entity we have
+ * to take care of not charging to it service it has
+ * not received.
+ */
+ bfq_calc_finish(entity, entity->service);
+ entity->start = entity->finish;
+ sd->in_service_entity = NULL;
+ } else if (entity->tree == &st->active) {
+ /*
+ * Requeueing an entity due to a change of some
+ * next_in_service entity below it. We reuse the
+ * old start time.
+ */
+ bfq_active_extract(st, entity);
+ } else if (entity->tree == &st->idle) {
+ /*
+ * Must be on the idle tree, bfq_idle_extract() will
+ * check for that.
+ */
+ bfq_idle_extract(st, entity);
+ entity->start = bfq_gt(st->vtime, entity->finish) ?
+ st->vtime : entity->finish;
+ } else {
+ /*
+ * The finish time of the entity may be invalid, and
+ * it is in the past for sure, otherwise the queue
+ * would have been on the idle tree.
+ */
+ entity->start = st->vtime;
+ st->wsum += entity->weight;
+ bfq_get_entity(entity);
+
+ BUG_ON(entity->on_st);
+ entity->on_st = 1;
+ }
+
+ st = __bfq_entity_update_weight_prio(st, entity);
+ bfq_calc_finish(entity, entity->budget);
+ bfq_active_insert(st, entity);
+}
+
+/**
+ * bfq_activate_entity - activate an entity and its ancestors if necessary.
+ * @entity: the entity to activate.
+ *
+ * Activate @entity and all the entities on the path from it to the root.
+ */
+static void bfq_activate_entity(struct bfq_entity *entity)
+{
+ struct bfq_sched_data *sd;
+
+ for_each_entity(entity) {
+ __bfq_activate_entity(entity);
+
+ sd = entity->sched_data;
+ if (!bfq_update_next_in_service(sd))
+ /*
+ * No need to propagate the activation to the
+ * upper entities, as they will be updated when
+ * the in-service entity is rescheduled.
+ */
+ break;
+ }
+}
+
+/**
+ * __bfq_deactivate_entity - deactivate an entity from its service tree.
+ * @entity: the entity to deactivate.
+ * @requeue: if false, the entity will not be put into the idle tree.
+ *
+ * Deactivate an entity, independently from its previous state. If the
+ * entity was not on a service tree just return, otherwise if it is on
+ * any scheduler tree, extract it from that tree, and if necessary
+ * and if the caller did not specify @requeue, put it on the idle tree.
+ *
+ * Return %1 if the caller should update the entity hierarchy, i.e.,
+ * if the entity was in service or if it was the next_in_service for
+ * its sched_data; return %0 otherwise.
+ */
+static int __bfq_deactivate_entity(struct bfq_entity *entity, int requeue)
+{
+ struct bfq_sched_data *sd = entity->sched_data;
+ struct bfq_service_tree *st = bfq_entity_service_tree(entity);
+ int was_in_service = entity == sd->in_service_entity;
+ int ret = 0;
+
+ if (!entity->on_st)
+ return 0;
+
+ BUG_ON(was_in_service && entity->tree != NULL);
+
+ if (was_in_service) {
+ bfq_calc_finish(entity, entity->service);
+ sd->in_service_entity = NULL;
+ } else if (entity->tree == &st->active)
+ bfq_active_extract(st, entity);
+ else if (entity->tree == &st->idle)
+ bfq_idle_extract(st, entity);
+ else if (entity->tree != NULL)
+ BUG();
+
+ if (was_in_service || sd->next_in_service == entity)
+ ret = bfq_update_next_in_service(sd);
+
+ if (!requeue || !bfq_gt(entity->finish, st->vtime))
+ bfq_forget_entity(st, entity);
+ else
+ bfq_idle_insert(st, entity);
+
+ BUG_ON(sd->in_service_entity == entity);
+ BUG_ON(sd->next_in_service == entity);
+
+ return ret;
+}
+
+/**
+ * bfq_deactivate_entity - deactivate an entity.
+ * @entity: the entity to deactivate.
+ * @requeue: true if the entity can be put on the idle tree
+ */
+static void bfq_deactivate_entity(struct bfq_entity *entity, int requeue)
+{
+ struct bfq_sched_data *sd;
+ struct bfq_entity *parent;
+
+ for_each_entity_safe(entity, parent) {
+ sd = entity->sched_data;
+
+ if (!__bfq_deactivate_entity(entity, requeue))
+ /*
+ * The parent entity is still backlogged, and
+ * we don't need to update it as it is still
+ * in service.
+ */
+ break;
+
+ if (sd->next_in_service != NULL)
+ /*
+ * The parent entity is still backlogged and
+ * the budgets on the path towards the root
+ * need to be updated.
+ */
+ goto update;
+
+ /*
+ * If we reach there the parent is no more backlogged and
+ * we want to propagate the dequeue upwards.
+ */
+ requeue = 1;
+ }
+
+ return;
+
+update:
+ entity = parent;
+ for_each_entity(entity) {
+ __bfq_activate_entity(entity);
+
+ sd = entity->sched_data;
+ if (!bfq_update_next_in_service(sd))
+ break;
+ }
+}
+
+/**
+ * bfq_update_vtime - update vtime if necessary.
+ * @st: the service tree to act upon.
+ *
+ * If necessary update the service tree vtime to have at least one
+ * eligible entity, skipping to its start time. Assumes that the
+ * active tree of the device is not empty.
+ *
+ * NOTE: this hierarchical implementation updates vtimes quite often,
+ * we may end up with reactivated processes getting timestamps after a
+ * vtime skip done because we needed a ->first_active entity on some
+ * intermediate node.
+ */
+static void bfq_update_vtime(struct bfq_service_tree *st)
+{
+ struct bfq_entity *entry;
+ struct rb_node *node = st->active.rb_node;
+
+ entry = rb_entry(node, struct bfq_entity, rb_node);
+ if (bfq_gt(entry->min_start, st->vtime)) {
+ st->vtime = entry->min_start;
+ bfq_forget_idle(st);
+ }
+}
+
+/**
+ * bfq_first_active_entity - find the eligible entity with
+ * the smallest finish time
+ * @st: the service tree to select from.
+ *
+ * This function searches the first schedulable entity, starting from the
+ * root of the tree and going on the left every time on this side there is
+ * a subtree with at least one eligible (start >= vtime) entity. The path on
+ * the right is followed only if a) the left subtree contains no eligible
+ * entities and b) no eligible entity has been found yet.
+ */
+static struct bfq_entity *bfq_first_active_entity(struct bfq_service_tree *st)
+{
+ struct bfq_entity *entry, *first = NULL;
+ struct rb_node *node = st->active.rb_node;
+
+ while (node != NULL) {
+ entry = rb_entry(node, struct bfq_entity, rb_node);
+left:
+ if (!bfq_gt(entry->start, st->vtime))
+ first = entry;
+
+ BUG_ON(bfq_gt(entry->min_start, st->vtime));
+
+ if (node->rb_left != NULL) {
+ entry = rb_entry(node->rb_left,
+ struct bfq_entity, rb_node);
+ if (!bfq_gt(entry->min_start, st->vtime)) {
+ node = node->rb_left;
+ goto left;
+ }
+ }
+ if (first != NULL)
+ break;
+ node = node->rb_right;
+ }
+
+ BUG_ON(first == NULL && !RB_EMPTY_ROOT(&st->active));
+ return first;
+}
+
+/**
+ * __bfq_lookup_next_entity - return the first eligible entity in @st.
+ * @st: the service tree.
+ *
+ * Update the virtual time in @st and return the first eligible entity
+ * it contains.
+ */
+static struct bfq_entity *__bfq_lookup_next_entity(struct bfq_service_tree *st,
+ bool force)
+{
+ struct bfq_entity *entity, *new_next_in_service = NULL;
+
+ if (RB_EMPTY_ROOT(&st->active))
+ return NULL;
+
+ bfq_update_vtime(st);
+ entity = bfq_first_active_entity(st);
+ BUG_ON(bfq_gt(entity->start, st->vtime));
+
+ /*
+ * If the chosen entity does not match with the sched_data's
+ * next_in_service and we are forcedly serving the IDLE priority
+ * class tree, bubble up budget update.
+ */
+ if (unlikely(force && entity != entity->sched_data->next_in_service)) {
+ new_next_in_service = entity;
+ for_each_entity(new_next_in_service)
+ bfq_update_budget(new_next_in_service);
+ }
+
+ return entity;
+}
+
+/**
+ * bfq_lookup_next_entity - return the first eligible entity in @sd.
+ * @sd: the sched_data.
+ * @extract: if true the returned entity will be also extracted from @sd.
+ *
+ * NOTE: since we cache the next_in_service entity at each level of the
+ * hierarchy, the complexity of the lookup can be decreased with
+ * absolutely no effort just returning the cached next_in_service value;
+ * we prefer to do full lookups to test the consistency of * the data
+ * structures.
+ */
+static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd,
+ int extract,
+ struct bfq_data *bfqd)
+{
+ struct bfq_service_tree *st = sd->service_tree;
+ struct bfq_entity *entity;
+ int i = 0;
+
+ BUG_ON(sd->in_service_entity != NULL);
+
+ if (bfqd != NULL &&
+ jiffies - bfqd->bfq_class_idle_last_service > BFQ_CL_IDLE_TIMEOUT) {
+ entity = __bfq_lookup_next_entity(st + BFQ_IOPRIO_CLASSES - 1,
+ true);
+ if (entity != NULL) {
+ i = BFQ_IOPRIO_CLASSES - 1;
+ bfqd->bfq_class_idle_last_service = jiffies;
+ sd->next_in_service = entity;
+ }
+ }
+ for (; i < BFQ_IOPRIO_CLASSES; i++) {
+ entity = __bfq_lookup_next_entity(st + i, false);
+ if (entity != NULL) {
+ if (extract) {
+ bfq_check_next_in_service(sd, entity);
+ bfq_active_extract(st + i, entity);
+ sd->in_service_entity = entity;
+ sd->next_in_service = NULL;
+ }
+ break;
+ }
+ }
+
+ return entity;
+}
+
+/*
+ * Get next queue for service.
+ */
+static struct bfq_queue *bfq_get_next_queue(struct bfq_data *bfqd)
+{
+ struct bfq_entity *entity = NULL;
+ struct bfq_sched_data *sd;
+ struct bfq_queue *bfqq;
+
+ BUG_ON(bfqd->in_service_queue != NULL);
+
+ if (bfqd->busy_queues == 0)
+ return NULL;
+
+ sd = &bfqd->root_group->sched_data;
+ for (; sd != NULL; sd = entity->my_sched_data) {
+ entity = bfq_lookup_next_entity(sd, 1, bfqd);
+ BUG_ON(entity == NULL);
+ entity->service = 0;
+ }
+
+ bfqq = bfq_entity_to_bfqq(entity);
+ BUG_ON(bfqq == NULL);
+
+ return bfqq;
+}
+
+static void __bfq_bfqd_reset_in_service(struct bfq_data *bfqd)
+{
+ if (bfqd->in_service_bic != NULL) {
+ put_io_context(bfqd->in_service_bic->icq.ioc);
+ bfqd->in_service_bic = NULL;
+ }
+
+ bfqd->in_service_queue = NULL;
+ del_timer(&bfqd->idle_slice_timer);
+}
+
+static void bfq_deactivate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ int requeue)
+{
+ struct bfq_entity *entity = &bfqq->entity;
+
+ if (bfqq == bfqd->in_service_queue)
+ __bfq_bfqd_reset_in_service(bfqd);
+
+ bfq_deactivate_entity(entity, requeue);
+}
+
+static void bfq_activate_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+{
+ struct bfq_entity *entity = &bfqq->entity;
+
+ bfq_activate_entity(entity);
+}
+
+/*
+ * Called when the bfqq no longer has requests pending, remove it from
+ * the service tree.
+ */
+static void bfq_del_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq,
+ int requeue)
+{
+ BUG_ON(!bfq_bfqq_busy(bfqq));
+ BUG_ON(!RB_EMPTY_ROOT(&bfqq->sort_list));
+
+ bfq_log_bfqq(bfqd, bfqq, "del from busy");
+
+ bfq_clear_bfqq_busy(bfqq);
+
+ BUG_ON(bfqd->busy_queues == 0);
+ bfqd->busy_queues--;
+
+ if (!bfqq->dispatched) {
+ bfq_weights_tree_remove(bfqd, &bfqq->entity,
+ &bfqd->queue_weights_tree);
+ if (!blk_queue_nonrot(bfqd->queue)) {
+ BUG_ON(!bfqd->busy_in_flight_queues);
+ bfqd->busy_in_flight_queues--;
+ if (bfq_bfqq_constantly_seeky(bfqq)) {
+ BUG_ON(!bfqd->
+ const_seeky_busy_in_flight_queues);
+ bfqd->const_seeky_busy_in_flight_queues--;
+ }
+ }
+ }
+ if (bfqq->wr_coeff > 1)
+ bfqd->wr_busy_queues--;
+
+ bfq_deactivate_bfqq(bfqd, bfqq, requeue);
+}
+
+/*
+ * Called when an inactive queue receives a new request.
+ */
+static void bfq_add_bfqq_busy(struct bfq_data *bfqd, struct bfq_queue *bfqq)
+{
+ BUG_ON(bfq_bfqq_busy(bfqq));
+ BUG_ON(bfqq == bfqd->in_service_queue);
+
+ bfq_log_bfqq(bfqd, bfqq, "add to busy");
+
+ bfq_activate_bfqq(bfqd, bfqq);
+
+ bfq_mark_bfqq_busy(bfqq);
+ bfqd->busy_queues++;
+
+ if (!bfqq->dispatched) {
+ if (bfqq->wr_coeff == 1)
+ bfq_weights_tree_add(bfqd, &bfqq->entity,
+ &bfqd->queue_weights_tree);
+ if (!blk_queue_nonrot(bfqd->queue)) {
+ bfqd->busy_in_flight_queues++;
+ if (bfq_bfqq_constantly_seeky(bfqq))
+ bfqd->const_seeky_busy_in_flight_queues++;
+ }
+ }
+ if (bfqq->wr_coeff > 1)
+ bfqd->wr_busy_queues++;
+}
diff --git a/block/bfq.h b/block/bfq.h
new file mode 100644
index 0000000..9428d71
--- /dev/null
+++ b/block/bfq.h
@@ -0,0 +1,809 @@
+/*
+ * BFQ-v7r7 for 3.4.0: data structures and common functions prototypes.
+ *
+ * Based on ideas and code from CFQ:
+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
+ *
+ * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
+ * Paolo Valente <paolo.valente@unimore.it>
+ *
+ * Copyright (C) 2010 Paolo Valente <paolo.valente@unimore.it>
+ */
+
+#ifndef _BFQ_H
+#define _BFQ_H
+
+#include <linux/blktrace_api.h>
+#include <linux/hrtimer.h>
+#include <linux/ioprio.h>
+#include <linux/rbtree.h>
+
+#define BFQ_IOPRIO_CLASSES 3
+#define BFQ_CL_IDLE_TIMEOUT (HZ/5)
+
+#define BFQ_MIN_WEIGHT 1
+#define BFQ_MAX_WEIGHT 1000
+
+#define BFQ_DEFAULT_QUEUE_IOPRIO 4
+
+#define BFQ_DEFAULT_GRP_WEIGHT 10
+#define BFQ_DEFAULT_GRP_IOPRIO 0
+#define BFQ_DEFAULT_GRP_CLASS IOPRIO_CLASS_BE
+
+struct bfq_entity;
+
+/**
+ * struct bfq_service_tree - per ioprio_class service tree.
+ * @active: tree for active entities (i.e., those backlogged).
+ * @idle: tree for idle entities (i.e., those not backlogged, with V <= F_i).
+ * @first_idle: idle entity with minimum F_i.
+ * @last_idle: idle entity with maximum F_i.
+ * @vtime: scheduler virtual time.
+ * @wsum: scheduler weight sum; active and idle entities contribute to it.
+ *
+ * Each service tree represents a B-WF2Q+ scheduler on its own. Each
+ * ioprio_class has its own independent scheduler, and so its own
+ * bfq_service_tree. All the fields are protected by the queue lock
+ * of the containing bfqd.
+ */
+struct bfq_service_tree {
+ struct rb_root active;
+ struct rb_root idle;
+
+ struct bfq_entity *first_idle;
+ struct bfq_entity *last_idle;
+
+ u64 vtime;
+ unsigned long wsum;
+};
+
+/**
+ * struct bfq_sched_data - multi-class scheduler.
+ * @in_service_entity: entity in service.
+ * @next_in_service: head-of-the-line entity in the scheduler.
+ * @service_tree: array of service trees, one per ioprio_class.
+ *
+ * bfq_sched_data is the basic scheduler queue. It supports three
+ * ioprio_classes, and can be used either as a toplevel queue or as
+ * an intermediate queue on a hierarchical setup.
+ * @next_in_service points to the active entity of the sched_data
+ * service trees that will be scheduled next.
+ *
+ * The supported ioprio_classes are the same as in CFQ, in descending
+ * priority order, IOPRIO_CLASS_RT, IOPRIO_CLASS_BE, IOPRIO_CLASS_IDLE.
+ * Requests from higher priority queues are served before all the
+ * requests from lower priority queues; among requests of the same
+ * queue requests are served according to B-WF2Q+.
+ * All the fields are protected by the queue lock of the containing bfqd.
+ */
+struct bfq_sched_data {
+ struct bfq_entity *in_service_entity;
+ struct bfq_entity *next_in_service;
+ struct bfq_service_tree service_tree[BFQ_IOPRIO_CLASSES];
+};
+
+/**
+ * struct bfq_weight_counter - counter of the number of all active entities
+ * with a given weight.
+ * @weight: weight of the entities that this counter refers to.
+ * @num_active: number of active entities with this weight.
+ * @weights_node: weights tree member (see bfq_data's @queue_weights_tree
+ * and @group_weights_tree).
+ */
+struct bfq_weight_counter {
+ short int weight;
+ unsigned int num_active;
+ struct rb_node weights_node;
+};
+
+/**
+ * struct bfq_entity - schedulable entity.
+ * @rb_node: service_tree member.
+ * @weight_counter: pointer to the weight counter associated with this entity.
+ * @on_st: flag, true if the entity is on a tree (either the active or
+ * the idle one of its service_tree).
+ * @finish: B-WF2Q+ finish timestamp (aka F_i).
+ * @start: B-WF2Q+ start timestamp (aka S_i).
+ * @tree: tree the entity is enqueued into; %NULL if not on a tree.
+ * @min_start: minimum start time of the (active) subtree rooted at
+ * this entity; used for O(log N) lookups into active trees.
+ * @service: service received during the last round of service.
+ * @budget: budget used to calculate F_i; F_i = S_i + @budget / @weight.
+ * @weight: weight of the queue
+ * @parent: parent entity, for hierarchical scheduling.
+ * @my_sched_data: for non-leaf nodes in the cgroup hierarchy, the
+ * associated scheduler queue, %NULL on leaf nodes.
+ * @sched_data: the scheduler queue this entity belongs to.
+ * @ioprio: the ioprio in use.
+ * @new_weight: when a weight change is requested, the new weight value.
+ * @orig_weight: original weight, used to implement weight boosting
+ * @new_ioprio: when an ioprio change is requested, the new ioprio value.
+ * @ioprio_class: the ioprio_class in use.
+ * @new_ioprio_class: when an ioprio_class change is requested, the new
+ * ioprio_class value.
+ * @ioprio_changed: flag, true when the user requested a weight, ioprio or
+ * ioprio_class change.
+ *
+ * A bfq_entity is used to represent either a bfq_queue (leaf node in the
+ * cgroup hierarchy) or a bfq_group into the upper level scheduler. Each
+ * entity belongs to the sched_data of the parent group in the cgroup
+ * hierarchy. Non-leaf entities have also their own sched_data, stored
+ * in @my_sched_data.
+ *
+ * Each entity stores independently its priority values; this would
+ * allow different weights on different devices, but this
+ * functionality is not exported to userspace by now. Priorities and
+ * weights are updated lazily, first storing the new values into the
+ * new_* fields, then setting the @ioprio_changed flag. As soon as
+ * there is a transition in the entity state that allows the priority
+ * update to take place the effective and the requested priority
+ * values are synchronized.
+ *
+ * Unless cgroups are used, the weight value is calculated from the
+ * ioprio to export the same interface as CFQ. When dealing with
+ * ``well-behaved'' queues (i.e., queues that do not spend too much
+ * time to consume their budget and have true sequential behavior, and
+ * when there are no external factors breaking anticipation) the
+ * relative weights at each level of the cgroups hierarchy should be
+ * guaranteed. All the fields are protected by the queue lock of the
+ * containing bfqd.
+ */
+struct bfq_entity {
+ struct rb_node rb_node;
+ struct bfq_weight_counter *weight_counter;
+
+ int on_st;
+
+ u64 finish;
+ u64 start;
+
+ struct rb_root *tree;
+
+ u64 min_start;
+
+ unsigned long service, budget;
+ unsigned short weight, new_weight;
+ unsigned short orig_weight;
+
+ struct bfq_entity *parent;
+
+ struct bfq_sched_data *my_sched_data;
+ struct bfq_sched_data *sched_data;
+
+ unsigned short ioprio, new_ioprio;
+ unsigned short ioprio_class, new_ioprio_class;
+
+ int ioprio_changed;
+};
+
+struct bfq_group;
+
+/**
+ * struct bfq_queue - leaf schedulable entity.
+ * @ref: reference counter.
+ * @bfqd: parent bfq_data.
+ * @new_bfqq: shared bfq_queue if queue is cooperating with
+ * one or more other queues.
+ * @pos_node: request-position tree member (see bfq_data's @rq_pos_tree).
+ * @pos_root: request-position tree root (see bfq_data's @rq_pos_tree).
+ * @sort_list: sorted list of pending requests.
+ * @next_rq: if fifo isn't expired, next request to serve.
+ * @queued: nr of requests queued in @sort_list.
+ * @allocated: currently allocated requests.
+ * @meta_pending: pending metadata requests.
+ * @fifo: fifo list of requests in sort_list.
+ * @entity: entity representing this queue in the scheduler.
+ * @max_budget: maximum budget allowed from the feedback mechanism.
+ * @budget_timeout: budget expiration (in jiffies).
+ * @dispatched: number of requests on the dispatch list or inside driver.
+ * @flags: status flags.
+ * @bfqq_list: node for active/idle bfqq list inside our bfqd.
+ * @burst_list_node: node for the device's burst list.
+ * @seek_samples: number of seeks sampled
+ * @seek_total: sum of the distances of the seeks sampled
+ * @seek_mean: mean seek distance
+ * @last_request_pos: position of the last request enqueued
+ * @requests_within_timer: number of consecutive pairs of request completion
+ * and arrival, such that the queue becomes idle
+ * after the completion, but the next request arrives
+ * within an idle time slice; used only if the queue's
+ * IO_bound has been cleared.
+ * @pid: pid of the process owning the queue, used for logging purposes.
+ * @last_wr_start_finish: start time of the current weight-raising period if
+ * the @bfq-queue is being weight-raised, otherwise
+ * finish time of the last weight-raising period
+ * @wr_cur_max_time: current max raising time for this queue
+ * @soft_rt_next_start: minimum time instant such that, only if a new
+ * request is enqueued after this time instant in an
+ * idle @bfq_queue with no outstanding requests, then
+ * the task associated with the queue it is deemed as
+ * soft real-time (see the comments to the function
+ * bfq_bfqq_softrt_next_start())
+ * @last_idle_bklogged: time of the last transition of the @bfq_queue from
+ * idle to backlogged
+ * @service_from_backlogged: cumulative service received from the @bfq_queue
+ * since the last transition from idle to
+ * backlogged
+ * @bic: pointer to the bfq_io_cq owning the bfq_queue, set to %NULL if the
+ * queue is shared
+ *
+ * A bfq_queue is a leaf request queue; it can be associated with an
+ * io_context or more, if it is async or shared between cooperating
+ * processes. @cgroup holds a reference to the cgroup, to be sure that it
+ * does not disappear while a bfqq still references it (mostly to avoid
+ * races between request issuing and task migration followed by cgroup
+ * destruction).
+ * All the fields are protected by the queue lock of the containing bfqd.
+ */
+struct bfq_queue {
+ atomic_t ref;
+ struct bfq_data *bfqd;
+
+ /* fields for cooperating queues handling */
+ struct bfq_queue *new_bfqq;
+ struct rb_node pos_node;
+ struct rb_root *pos_root;
+
+ struct rb_root sort_list;
+ struct request *next_rq;
+ int queued[2];
+ int allocated[2];
+ int meta_pending;
+ struct list_head fifo;
+
+ struct bfq_entity entity;
+
+ unsigned long max_budget;
+ unsigned long budget_timeout;
+
+ int dispatched;
+
+ unsigned int flags;
+
+ struct list_head bfqq_list;
+
+ struct hlist_node burst_list_node;
+
+ unsigned int seek_samples;
+ u64 seek_total;
+ sector_t seek_mean;
+ sector_t last_request_pos;
+
+ unsigned int requests_within_timer;
+
+ pid_t pid;
+ struct bfq_io_cq *bic;
+
+ /* weight-raising fields */
+ unsigned long wr_cur_max_time;
+ unsigned long soft_rt_next_start;
+ unsigned long last_wr_start_finish;
+ unsigned int wr_coeff;
+ unsigned long last_idle_bklogged;
+ unsigned long service_from_backlogged;
+};
+
+/**
+ * struct bfq_ttime - per process thinktime stats.
+ * @ttime_total: total process thinktime
+ * @ttime_samples: number of thinktime samples
+ * @ttime_mean: average process thinktime
+ */
+struct bfq_ttime {
+ unsigned long last_end_request;
+
+ unsigned long ttime_total;
+ unsigned long ttime_samples;
+ unsigned long ttime_mean;
+};
+
+/**
+ * struct bfq_io_cq - per (request_queue, io_context) structure.
+ * @icq: associated io_cq structure
+ * @bfqq: array of two process queues, the sync and the async
+ * @ttime: associated @bfq_ttime struct
+ * @wr_time_left: snapshot of the time left before weight raising ends
+ * for the sync queue associated to this process; this
+ * snapshot is taken to remember this value while the weight
+ * raising is suspended because the queue is merged with a
+ * shared queue, and is used to set @raising_cur_max_time
+ * when the queue is split from the shared queue and its
+ * weight is raised again
+ * @saved_idle_window: same purpose as the previous field for the idle
+ * window
+ * @saved_IO_bound: same purpose as the previous two fields for the I/O
+ * bound classification of a queue
+ * @saved_in_large_burst: same purpose as the previous fields for the
+ * value of the field keeping the queue's belonging
+ * to a large burst
+ * @was_in_burst_list: true if the queue belonged to a burst list
+ * before its merge with another cooperating queue
+ * @cooperations: counter of consecutive successful queue merges underwent
+ * by any of the process' @bfq_queues
+ * @failed_cooperations: counter of consecutive failed queue merges of any
+ * of the process' @bfq_queues
+ */
+struct bfq_io_cq {
+ struct io_cq icq; /* must be the first member */
+ struct bfq_queue *bfqq[2];
+ struct bfq_ttime ttime;
+
+ unsigned int wr_time_left;
+ bool saved_idle_window;
+ bool saved_IO_bound;
+
+ bool saved_in_large_burst;
+ bool was_in_burst_list;
+
+ unsigned int cooperations;
+ unsigned int failed_cooperations;
+};
+
+enum bfq_device_speed {
+ BFQ_BFQD_FAST,
+ BFQ_BFQD_SLOW,
+};
+
+/**
+ * struct bfq_data - per device data structure.
+ * @queue: request queue for the managed device.
+ * @root_group: root bfq_group for the device.
+ * @rq_pos_tree: rbtree sorted by next_request position, used when
+ * determining if two or more queues have interleaving
+ * requests (see bfq_close_cooperator()).
+ * @active_numerous_groups: number of bfq_groups containing more than one
+ * active @bfq_entity.
+ * @queue_weights_tree: rbtree of weight counters of @bfq_queues, sorted by
+ * weight. Used to keep track of whether all @bfq_queues
+ * have the same weight. The tree contains one counter
+ * for each distinct weight associated to some active
+ * and not weight-raised @bfq_queue (see the comments to
+ * the functions bfq_weights_tree_[add|remove] for
+ * further details).
+ * @group_weights_tree: rbtree of non-queue @bfq_entity weight counters, sorted
+ * by weight. Used to keep track of whether all
+ * @bfq_groups have the same weight. The tree contains
+ * one counter for each distinct weight associated to
+ * some active @bfq_group (see the comments to the
+ * functions bfq_weights_tree_[add|remove] for further
+ * details).
+ * @busy_queues: number of bfq_queues containing requests (including the
+ * queue in service, even if it is idling).
+ * @busy_in_flight_queues: number of @bfq_queues containing pending or
+ * in-flight requests, plus the @bfq_queue in
+ * service, even if idle but waiting for the
+ * possible arrival of its next sync request. This
+ * field is updated only if the device is rotational,
+ * but used only if the device is also NCQ-capable.
+ * The reason why the field is updated also for non-
+ * NCQ-capable rotational devices is related to the
+ * fact that the value of @hw_tag may be set also
+ * later than when busy_in_flight_queues may need to
+ * be incremented for the first time(s). Taking also
+ * this possibility into account, to avoid unbalanced
+ * increments/decrements, would imply more overhead
+ * than just updating busy_in_flight_queues
+ * regardless of the value of @hw_tag.
+ * @const_seeky_busy_in_flight_queues: number of constantly-seeky @bfq_queues
+ * (that is, seeky queues that expired
+ * for budget timeout at least once)
+ * containing pending or in-flight
+ * requests, including the in-service
+ * @bfq_queue if constantly seeky. This
+ * field is updated only if the device
+ * is rotational, but used only if the
+ * device is also NCQ-capable (see the
+ * comments to @busy_in_flight_queues).
+ * @wr_busy_queues: number of weight-raised busy @bfq_queues.
+ * @queued: number of queued requests.
+ * @rq_in_driver: number of requests dispatched and waiting for completion.
+ * @sync_flight: number of sync requests in the driver.
+ * @max_rq_in_driver: max number of reqs in driver in the last
+ * @hw_tag_samples completed requests.
+ * @hw_tag_samples: nr of samples used to calculate hw_tag.
+ * @hw_tag: flag set to one if the driver is showing a queueing behavior.
+ * @budgets_assigned: number of budgets assigned.
+ * @idle_slice_timer: timer set when idling for the next sequential request
+ * from the queue in service.
+ * @unplug_work: delayed work to restart dispatching on the request queue.
+ * @in_service_queue: bfq_queue in service.
+ * @in_service_bic: bfq_io_cq (bic) associated with the @in_service_queue.
+ * @last_position: on-disk position of the last served request.
+ * @last_budget_start: beginning of the last budget.
+ * @last_idling_start: beginning of the last idle slice.
+ * @peak_rate: peak transfer rate observed for a budget.
+ * @peak_rate_samples: number of samples used to calculate @peak_rate.
+ * @bfq_max_budget: maximum budget allotted to a bfq_queue before
+ * rescheduling.
+ * @group_list: list of all the bfq_groups active on the device.
+ * @active_list: list of all the bfq_queues active on the device.
+ * @idle_list: list of all the bfq_queues idle on the device.
+ * @bfq_quantum: max number of requests dispatched per dispatch round.
+ * @bfq_fifo_expire: timeout for async/sync requests; when it expires
+ * requests are served in fifo order.
+ * @bfq_back_penalty: weight of backward seeks wrt forward ones.
+ * @bfq_back_max: maximum allowed backward seek.
+ * @bfq_slice_idle: maximum idling time.
+ * @bfq_user_max_budget: user-configured max budget value
+ * (0 for auto-tuning).
+ * @bfq_max_budget_async_rq: maximum budget (in nr of requests) allotted to
+ * async queues.
+ * @bfq_timeout: timeout for bfq_queues to consume their budget; used to
+ * to prevent seeky queues to impose long latencies to well
+ * behaved ones (this also implies that seeky queues cannot
+ * receive guarantees in the service domain; after a timeout
+ * they are charged for the whole allocated budget, to try
+ * to preserve a behavior reasonably fair among them, but
+ * without service-domain guarantees).
+ * @bfq_coop_thresh: number of queue merges after which a @bfq_queue is
+ * no more granted any weight-raising.
+ * @bfq_failed_cooperations: number of consecutive failed cooperation
+ * chances after which weight-raising is restored
+ * to a queue subject to more than bfq_coop_thresh
+ * queue merges.
+ * @bfq_requests_within_timer: number of consecutive requests that must be
+ * issued within the idle time slice to set
+ * again idling to a queue which was marked as
+ * non-I/O-bound (see the definition of the
+ * IO_bound flag for further details).
+ * @last_ins_in_burst: last time at which a queue entered the current
+ * burst of queues being activated shortly after
+ * each other; for more details about this and the
+ * following parameters related to a burst of
+ * activations, see the comments to the function
+ * @bfq_handle_burst.
+ * @bfq_burst_interval: reference time interval used to decide whether a
+ * queue has been activated shortly after
+ * @last_ins_in_burst.
+ * @burst_size: number of queues in the current burst of queue activations.
+ * @bfq_large_burst_thresh: maximum burst size above which the current
+ * queue-activation burst is deemed as 'large'.
+ * @large_burst: true if a large queue-activation burst is in progress.
+ * @burst_list: head of the burst list (as for the above fields, more details
+ * in the comments to the function bfq_handle_burst).
+ * @low_latency: if set to true, low-latency heuristics are enabled.
+ * @bfq_wr_coeff: maximum factor by which the weight of a weight-raised
+ * queue is multiplied.
+ * @bfq_wr_max_time: maximum duration of a weight-raising period (jiffies).
+ * @bfq_wr_rt_max_time: maximum duration for soft real-time processes.
+ * @bfq_wr_min_idle_time: minimum idle period after which weight-raising
+ * may be reactivated for a queue (in jiffies).
+ * @bfq_wr_min_inter_arr_async: minimum period between request arrivals
+ * after which weight-raising may be
+ * reactivated for an already busy queue
+ * (in jiffies).
+ * @bfq_wr_max_softrt_rate: max service-rate for a soft real-time queue,
+ * sectors per seconds.
+ * @RT_prod: cached value of the product R*T used for computing the maximum
+ * duration of the weight raising automatically.
+ * @device_speed: device-speed class for the low-latency heuristic.
+ * @oom_bfqq: fallback dummy bfqq for extreme OOM conditions.
+ *
+ * All the fields are protected by the @queue lock.
+ */
+struct bfq_data {
+ struct request_queue *queue;
+
+ struct bfq_group *root_group;
+ struct rb_root rq_pos_tree;
+
+#ifdef CONFIG_CGROUP_BFQIO
+ int active_numerous_groups;
+#endif
+
+ struct rb_root queue_weights_tree;
+ struct rb_root group_weights_tree;
+
+ int busy_queues;
+ int busy_in_flight_queues;
+ int const_seeky_busy_in_flight_queues;
+ int wr_busy_queues;
+ int queued;
+ int rq_in_driver;
+ int sync_flight;
+
+ int max_rq_in_driver;
+ int hw_tag_samples;
+ int hw_tag;
+
+ int budgets_assigned;
+
+ struct timer_list idle_slice_timer;
+ struct work_struct unplug_work;
+
+ struct bfq_queue *in_service_queue;
+ struct bfq_io_cq *in_service_bic;
+
+ sector_t last_position;
+
+ ktime_t last_budget_start;
+ ktime_t last_idling_start;
+ int peak_rate_samples;
+ u64 peak_rate;
+ unsigned long bfq_max_budget;
+
+ struct hlist_head group_list;
+ struct list_head active_list;
+ struct list_head idle_list;
+
+ unsigned int bfq_quantum;
+ unsigned int bfq_fifo_expire[2];
+ unsigned int bfq_back_penalty;
+ unsigned int bfq_back_max;
+ unsigned int bfq_slice_idle;
+ u64 bfq_class_idle_last_service;
+
+ unsigned int bfq_user_max_budget;
+ unsigned int bfq_max_budget_async_rq;
+ unsigned int bfq_timeout[2];
+
+ unsigned int bfq_coop_thresh;
+ unsigned int bfq_failed_cooperations;
+ unsigned int bfq_requests_within_timer;
+
+ unsigned long last_ins_in_burst;
+ unsigned long bfq_burst_interval;
+ int burst_size;
+ unsigned long bfq_large_burst_thresh;
+ bool large_burst;
+ struct hlist_head burst_list;
+
+ bool low_latency;
+
+ /* parameters of the low_latency heuristics */
+ unsigned int bfq_wr_coeff;
+ unsigned int bfq_wr_max_time;
+ unsigned int bfq_wr_rt_max_time;
+ unsigned int bfq_wr_min_idle_time;
+ unsigned long bfq_wr_min_inter_arr_async;
+ unsigned int bfq_wr_max_softrt_rate;
+ u64 RT_prod;
+ enum bfq_device_speed device_speed;
+
+ struct bfq_queue oom_bfqq;
+};
+
+enum bfqq_state_flags {
+ BFQ_BFQQ_FLAG_busy = 0, /* has requests or is in service */
+ BFQ_BFQQ_FLAG_wait_request, /* waiting for a request */
+ BFQ_BFQQ_FLAG_must_alloc, /* must be allowed rq alloc */
+ BFQ_BFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
+ BFQ_BFQQ_FLAG_idle_window, /* slice idling enabled */
+ BFQ_BFQQ_FLAG_prio_changed, /* task priority has changed */
+ BFQ_BFQQ_FLAG_sync, /* synchronous queue */
+ BFQ_BFQQ_FLAG_budget_new, /* no completion with this budget */
+ BFQ_BFQQ_FLAG_IO_bound, /*
+ * bfqq has timed-out at least once
+ * having consumed at most 2/10 of
+ * its budget
+ */
+ BFQ_BFQQ_FLAG_in_large_burst, /*
+ * bfqq activated in a large burst,
+ * see comments to bfq_handle_burst.
+ */
+ BFQ_BFQQ_FLAG_constantly_seeky, /*
+ * bfqq has proved to be slow and
+ * seeky until budget timeout
+ */
+ BFQ_BFQQ_FLAG_softrt_update, /*
+ * may need softrt-next-start
+ * update
+ */
+ BFQ_BFQQ_FLAG_coop, /* bfqq is shared */
+ BFQ_BFQQ_FLAG_split_coop, /* shared bfqq will be split */
+ BFQ_BFQQ_FLAG_just_split, /* queue has just been split */
+};
+
+#define BFQ_BFQQ_FNS(name) \
+static inline void bfq_mark_bfqq_##name(struct bfq_queue *bfqq) \
+{ \
+ (bfqq)->flags |= (1 << BFQ_BFQQ_FLAG_##name); \
+} \
+static inline void bfq_clear_bfqq_##name(struct bfq_queue *bfqq) \
+{ \
+ (bfqq)->flags &= ~(1 << BFQ_BFQQ_FLAG_##name); \
+} \
+static inline int bfq_bfqq_##name(const struct bfq_queue *bfqq) \
+{ \
+ return ((bfqq)->flags & (1 << BFQ_BFQQ_FLAG_##name)) != 0; \
+}
+
+BFQ_BFQQ_FNS(busy);
+BFQ_BFQQ_FNS(wait_request);
+BFQ_BFQQ_FNS(must_alloc);
+BFQ_BFQQ_FNS(fifo_expire);
+BFQ_BFQQ_FNS(idle_window);
+BFQ_BFQQ_FNS(prio_changed);
+BFQ_BFQQ_FNS(sync);
+BFQ_BFQQ_FNS(budget_new);
+BFQ_BFQQ_FNS(IO_bound);
+BFQ_BFQQ_FNS(in_large_burst);
+BFQ_BFQQ_FNS(constantly_seeky);
+BFQ_BFQQ_FNS(coop);
+BFQ_BFQQ_FNS(split_coop);
+BFQ_BFQQ_FNS(just_split);
+BFQ_BFQQ_FNS(softrt_update);
+#undef BFQ_BFQQ_FNS
+
+/* Logging facilities. */
+#define bfq_log_bfqq(bfqd, bfqq, fmt, args...) \
+ blk_add_trace_msg((bfqd)->queue, "bfq%d " fmt, (bfqq)->pid, ##args)
+
+#define bfq_log(bfqd, fmt, args...) \
+ blk_add_trace_msg((bfqd)->queue, "bfq " fmt, ##args)
+
+/* Expiration reasons. */
+enum bfqq_expiration {
+ BFQ_BFQQ_TOO_IDLE = 0, /*
+ * queue has been idling for
+ * too long
+ */
+ BFQ_BFQQ_BUDGET_TIMEOUT, /* budget took too long to be used */
+ BFQ_BFQQ_BUDGET_EXHAUSTED, /* budget consumed */
+ BFQ_BFQQ_NO_MORE_REQUESTS, /* the queue has no more requests */
+};
+
+#ifdef CONFIG_CGROUP_BFQIO
+/**
+ * struct bfq_group - per (device, cgroup) data structure.
+ * @entity: schedulable entity to insert into the parent group sched_data.
+ * @sched_data: own sched_data, to contain child entities (they may be
+ * both bfq_queues and bfq_groups).
+ * @group_node: node to be inserted into the bfqio_cgroup->group_data
+ * list of the containing cgroup's bfqio_cgroup.
+ * @bfqd_node: node to be inserted into the @bfqd->group_list list
+ * of the groups active on the same device; used for cleanup.
+ * @bfqd: the bfq_data for the device this group acts upon.
+ * @async_bfqq: array of async queues for all the tasks belonging to
+ * the group, one queue per ioprio value per ioprio_class,
+ * except for the idle class that has only one queue.
+ * @async_idle_bfqq: async queue for the idle class (ioprio is ignored).
+ * @my_entity: pointer to @entity, %NULL for the toplevel group; used
+ * to avoid too many special cases during group creation/
+ * migration.
+ * @active_entities: number of active entities belonging to the group;
+ * unused for the root group. Used to know whether there
+ * are groups with more than one active @bfq_entity
+ * (see the comments to the function
+ * bfq_bfqq_must_not_expire()).
+ *
+ * Each (device, cgroup) pair has its own bfq_group, i.e., for each cgroup
+ * there is a set of bfq_groups, each one collecting the lower-level
+ * entities belonging to the group that are acting on the same device.
+ *
+ * Locking works as follows:
+ * o @group_node is protected by the bfqio_cgroup lock, and is accessed
+ * via RCU from its readers.
+ * o @bfqd is protected by the queue lock, RCU is used to access it
+ * from the readers.
+ * o All the other fields are protected by the @bfqd queue lock.
+ */
+struct bfq_group {
+ struct bfq_entity entity;
+ struct bfq_sched_data sched_data;
+
+ struct hlist_node group_node;
+ struct hlist_node bfqd_node;
+
+ void *bfqd;
+
+ struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
+ struct bfq_queue *async_idle_bfqq;
+
+ struct bfq_entity *my_entity;
+
+ int active_entities;
+};
+
+/**
+ * struct bfqio_cgroup - bfq cgroup data structure.
+ * @css: subsystem state for bfq in the containing cgroup.
+ * @weight: cgroup weight.
+ * @ioprio: cgroup ioprio.
+ * @ioprio_class: cgroup ioprio_class.
+ * @lock: spinlock that protects @ioprio, @ioprio_class and @group_data.
+ * @group_data: list containing the bfq_group belonging to this cgroup.
+ *
+ * @group_data is accessed using RCU, with @lock protecting the updates,
+ * @ioprio and @ioprio_class are protected by @lock.
+ */
+struct bfqio_cgroup {
+ struct cgroup_subsys_state css;
+
+ unsigned short weight, ioprio, ioprio_class;
+
+ spinlock_t lock;
+ struct hlist_head group_data;
+};
+#else
+struct bfq_group {
+ struct bfq_sched_data sched_data;
+
+ struct bfq_queue *async_bfqq[2][IOPRIO_BE_NR];
+ struct bfq_queue *async_idle_bfqq;
+};
+#endif
+
+static inline struct bfq_service_tree *
+bfq_entity_service_tree(struct bfq_entity *entity)
+{
+ struct bfq_sched_data *sched_data = entity->sched_data;
+ unsigned int idx = entity->ioprio_class - 1;
+
+ BUG_ON(idx >= BFQ_IOPRIO_CLASSES);
+ BUG_ON(sched_data == NULL);
+
+ return sched_data->service_tree + idx;
+}
+
+static inline struct bfq_queue *bic_to_bfqq(struct bfq_io_cq *bic,
+ bool is_sync)
+{
+ return bic->bfqq[is_sync];
+}
+
+static inline void bic_set_bfqq(struct bfq_io_cq *bic,
+ struct bfq_queue *bfqq, bool is_sync)
+{
+ bic->bfqq[is_sync] = bfqq;
+}
+
+static inline struct bfq_data *bic_to_bfqd(struct bfq_io_cq *bic)
+{
+ return bic->icq.q->elevator->elevator_data;
+}
+
+/**
+ * bfq_get_bfqd_locked - get a lock to a bfqd using a RCU protected pointer.
+ * @ptr: a pointer to a bfqd.
+ * @flags: storage for the flags to be saved.
+ *
+ * This function allows bfqg->bfqd to be protected by the
+ * queue lock of the bfqd they reference; the pointer is dereferenced
+ * under RCU, so the storage for bfqd is assured to be safe as long
+ * as the RCU read side critical section does not end. After the
+ * bfqd->queue->queue_lock is taken the pointer is rechecked, to be
+ * sure that no other writer accessed it. If we raced with a writer,
+ * the function returns NULL, with the queue unlocked, otherwise it
+ * returns the dereferenced pointer, with the queue locked.
+ */
+static inline struct bfq_data *bfq_get_bfqd_locked(void **ptr,
+ unsigned long *flags)
+{
+ struct bfq_data *bfqd;
+
+ rcu_read_lock();
+ bfqd = rcu_dereference(*(struct bfq_data **)ptr);
+
+ if (bfqd != NULL) {
+ spin_lock_irqsave(bfqd->queue->queue_lock, *flags);
+ if (*ptr == bfqd)
+ goto out;
+ spin_unlock_irqrestore(bfqd->queue->queue_lock, *flags);
+ }
+
+ bfqd = NULL;
+out:
+ rcu_read_unlock();
+ return bfqd;
+}
+
+static inline void bfq_put_bfqd_unlock(struct bfq_data *bfqd,
+ unsigned long *flags)
+{
+ spin_unlock_irqrestore(bfqd->queue->queue_lock, *flags);
+}
+
+static void bfq_changed_ioprio(struct io_context *ioc,
+ struct bfq_io_cq *bic);
+static void bfq_put_queue(struct bfq_queue *bfqq);
+static void bfq_dispatch_insert(struct request_queue *q, struct request *rq);
+static struct bfq_queue *bfq_get_queue(struct bfq_data *bfqd,
+ struct bfq_group *bfqg, int is_sync,
+ struct io_context *ioc, gfp_t gfp_mask);
+static void bfq_end_wr_async_queues(struct bfq_data *bfqd,
+ struct bfq_group *bfqg);
+static void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg);
+static void bfq_exit_bfqq(struct bfq_data *bfqd, struct bfq_queue *bfqq);
+
+#endif /* _BFQ_H */
diff --git a/block/fiops-iosched.c b/block/fiops-iosched.c
new file mode 100644
index 0000000..671b1d3
--- /dev/null
+++ b/block/fiops-iosched.c
@@ -0,0 +1,753 @@
+/*
+ * IOPS based IO scheduler. Based on CFQ.
+ * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
+ * Shaohua Li <shli@kernel.org>
+ */
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/blkdev.h>
+#include <linux/elevator.h>
+#include <linux/jiffies.h>
+#include <linux/rbtree.h>
+#include <linux/ioprio.h>
+#include <linux/blktrace_api.h>
+#include "blk.h"
+
+#define VIOS_SCALE_SHIFT 10
+#define VIOS_SCALE (1 << VIOS_SCALE_SHIFT)
+
+#define VIOS_READ_SCALE (1)
+#define VIOS_WRITE_SCALE (1)
+#define VIOS_SYNC_SCALE (2)
+#define VIOS_ASYNC_SCALE (5)
+
+#define VIOS_PRIO_SCALE (5)
+
+struct fiops_rb_root {
+ struct rb_root rb;
+ struct rb_node *left;
+ unsigned count;
+
+ u64 min_vios;
+};
+#define FIOPS_RB_ROOT (struct fiops_rb_root) { .rb = RB_ROOT}
+
+enum wl_prio_t {
+ IDLE_WORKLOAD = 0,
+ BE_WORKLOAD = 1,
+ RT_WORKLOAD = 2,
+ FIOPS_PRIO_NR,
+};
+
+struct fiops_data {
+ struct request_queue *queue;
+
+ struct fiops_rb_root service_tree[FIOPS_PRIO_NR];
+
+ unsigned int busy_queues;
+ unsigned int in_flight[2];
+
+ struct work_struct unplug_work;
+
+ unsigned int read_scale;
+ unsigned int write_scale;
+ unsigned int sync_scale;
+ unsigned int async_scale;
+};
+
+struct fiops_ioc {
+ struct io_cq icq;
+
+ unsigned int flags;
+ struct fiops_data *fiopsd;
+ struct rb_node rb_node;
+ u64 vios; /* key in service_tree */
+ struct fiops_rb_root *service_tree;
+
+ unsigned int in_flight;
+
+ struct rb_root sort_list;
+ struct list_head fifo;
+
+ pid_t pid;
+ unsigned short ioprio;
+ enum wl_prio_t wl_type;
+};
+
+#define ioc_service_tree(ioc) (&((ioc)->fiopsd->service_tree[(ioc)->wl_type]))
+#define RQ_CIC(rq) icq_to_cic((rq)->elv.icq)
+
+enum ioc_state_flags {
+ FIOPS_IOC_FLAG_on_rr = 0, /* on round-robin busy list */
+ FIOPS_IOC_FLAG_prio_changed, /* task priority has changed */
+};
+
+#define FIOPS_IOC_FNS(name) \
+static inline void fiops_mark_ioc_##name(struct fiops_ioc *ioc) \
+{ \
+ ioc->flags |= (1 << FIOPS_IOC_FLAG_##name); \
+} \
+static inline void fiops_clear_ioc_##name(struct fiops_ioc *ioc) \
+{ \
+ ioc->flags &= ~(1 << FIOPS_IOC_FLAG_##name); \
+} \
+static inline int fiops_ioc_##name(const struct fiops_ioc *ioc) \
+{ \
+ return ((ioc)->flags & (1 << FIOPS_IOC_FLAG_##name)) != 0; \
+}
+
+FIOPS_IOC_FNS(on_rr);
+FIOPS_IOC_FNS(prio_changed);
+#undef FIOPS_IOC_FNS
+
+#define fiops_log_ioc(fiopsd, ioc, fmt, args...) \
+ blk_add_trace_msg((fiopsd)->queue, "ioc%d " fmt, (ioc)->pid, ##args)
+#define fiops_log(fiopsd, fmt, args...) \
+ blk_add_trace_msg((fiopsd)->queue, "fiops " fmt, ##args)
+
+enum wl_prio_t fiops_wl_type(short prio_class)
+{
+ if (prio_class == IOPRIO_CLASS_RT)
+ return RT_WORKLOAD;
+ if (prio_class == IOPRIO_CLASS_BE)
+ return BE_WORKLOAD;
+ return IDLE_WORKLOAD;
+}
+
+static inline struct fiops_ioc *icq_to_cic(struct io_cq *icq)
+{
+ /* cic->icq is the first member, %NULL will convert to %NULL */
+ return container_of(icq, struct fiops_ioc, icq);
+}
+
+static inline struct fiops_ioc *fiops_cic_lookup(struct fiops_data *fiopsd,
+ struct io_context *ioc)
+{
+ if (ioc)
+ return icq_to_cic(ioc_lookup_icq(ioc, fiopsd->queue));
+ return NULL;
+}
+
+/*
+ * The below is leftmost cache rbtree addon
+ */
+static struct fiops_ioc *fiops_rb_first(struct fiops_rb_root *root)
+{
+ /* Service tree is empty */
+ if (!root->count)
+ return NULL;
+
+ if (!root->left)
+ root->left = rb_first(&root->rb);
+
+ if (root->left)
+ return rb_entry(root->left, struct fiops_ioc, rb_node);
+
+ return NULL;
+}
+
+static void rb_erase_init(struct rb_node *n, struct rb_root *root)
+{
+ rb_erase(n, root);
+ RB_CLEAR_NODE(n);
+}
+
+static void fiops_rb_erase(struct rb_node *n, struct fiops_rb_root *root)
+{
+ if (root->left == n)
+ root->left = NULL;
+ rb_erase_init(n, &root->rb);
+ --root->count;
+}
+
+static inline u64 max_vios(u64 min_vios, u64 vios)
+{
+ s64 delta = (s64)(vios - min_vios);
+ if (delta > 0)
+ min_vios = vios;
+
+ return min_vios;
+}
+
+static void fiops_update_min_vios(struct fiops_rb_root *service_tree)
+{
+ struct fiops_ioc *ioc;
+
+ ioc = fiops_rb_first(service_tree);
+ if (!ioc)
+ return;
+ service_tree->min_vios = max_vios(service_tree->min_vios, ioc->vios);
+}
+
+/*
+ * The fiopsd->service_trees holds all pending fiops_ioc's that have
+ * requests waiting to be processed. It is sorted in the order that
+ * we will service the queues.
+ */
+static void fiops_service_tree_add(struct fiops_data *fiopsd,
+ struct fiops_ioc *ioc)
+{
+ struct rb_node **p, *parent;
+ struct fiops_ioc *__ioc;
+ struct fiops_rb_root *service_tree = ioc_service_tree(ioc);
+ u64 vios;
+ int left;
+
+ /* New added IOC */
+ if (RB_EMPTY_NODE(&ioc->rb_node)) {
+ if (ioc->in_flight > 0)
+ vios = ioc->vios;
+ else
+ vios = max_vios(service_tree->min_vios, ioc->vios);
+ } else {
+ vios = ioc->vios;
+ /* ioc->service_tree might not equal to service_tree */
+ fiops_rb_erase(&ioc->rb_node, ioc->service_tree);
+ ioc->service_tree = NULL;
+ }
+
+ fiops_log_ioc(fiopsd, ioc, "service tree add, vios %lld", vios);
+
+ left = 1;
+ parent = NULL;
+ ioc->service_tree = service_tree;
+ p = &service_tree->rb.rb_node;
+ while (*p) {
+ struct rb_node **n;
+
+ parent = *p;
+ __ioc = rb_entry(parent, struct fiops_ioc, rb_node);
+
+ /*
+ * sort by key, that represents service time.
+ */
+ if (vios < __ioc->vios)
+ n = &(*p)->rb_left;
+ else {
+ n = &(*p)->rb_right;
+ left = 0;
+ }
+
+ p = n;
+ }
+
+ if (left)
+ service_tree->left = &ioc->rb_node;
+
+ ioc->vios = vios;
+ rb_link_node(&ioc->rb_node, parent, p);
+ rb_insert_color(&ioc->rb_node, &service_tree->rb);
+ service_tree->count++;
+
+ fiops_update_min_vios(service_tree);
+}
+
+/*
+ * Update ioc's position in the service tree.
+ */
+static void fiops_resort_rr_list(struct fiops_data *fiopsd,
+ struct fiops_ioc *ioc)
+{
+ /*
+ * Resorting requires the ioc to be on the RR list already.
+ */
+ if (fiops_ioc_on_rr(ioc))
+ fiops_service_tree_add(fiopsd, ioc);
+}
+
+/*
+ * add to busy list of queues for service, trying to be fair in ordering
+ * the pending list according to last request service
+ */
+static void fiops_add_ioc_rr(struct fiops_data *fiopsd, struct fiops_ioc *ioc)
+{
+ BUG_ON(fiops_ioc_on_rr(ioc));
+ fiops_mark_ioc_on_rr(ioc);
+
+ fiopsd->busy_queues++;
+
+ fiops_resort_rr_list(fiopsd, ioc);
+}
+
+/*
+ * Called when the ioc no longer has requests pending, remove it from
+ * the service tree.
+ */
+static void fiops_del_ioc_rr(struct fiops_data *fiopsd, struct fiops_ioc *ioc)
+{
+ BUG_ON(!fiops_ioc_on_rr(ioc));
+ fiops_clear_ioc_on_rr(ioc);
+
+ if (!RB_EMPTY_NODE(&ioc->rb_node)) {
+ fiops_rb_erase(&ioc->rb_node, ioc->service_tree);
+ ioc->service_tree = NULL;
+ }
+
+ BUG_ON(!fiopsd->busy_queues);
+ fiopsd->busy_queues--;
+}
+
+/*
+ * rb tree support functions
+ */
+static void fiops_del_rq_rb(struct request *rq)
+{
+ struct fiops_ioc *ioc = RQ_CIC(rq);
+
+ elv_rb_del(&ioc->sort_list, rq);
+}
+
+static void fiops_add_rq_rb(struct request *rq)
+{
+ struct fiops_ioc *ioc = RQ_CIC(rq);
+ struct fiops_data *fiopsd = ioc->fiopsd;
+
+ elv_rb_add(&ioc->sort_list, rq);
+
+ if (!fiops_ioc_on_rr(ioc))
+ fiops_add_ioc_rr(fiopsd, ioc);
+}
+
+static void fiops_reposition_rq_rb(struct fiops_ioc *ioc, struct request *rq)
+{
+ elv_rb_del(&ioc->sort_list, rq);
+ fiops_add_rq_rb(rq);
+}
+
+static void fiops_remove_request(struct request *rq)
+{
+ list_del_init(&rq->queuelist);
+ fiops_del_rq_rb(rq);
+}
+
+static u64 fiops_scaled_vios(struct fiops_data *fiopsd,
+ struct fiops_ioc *ioc, struct request *rq)
+{
+ int vios = VIOS_SCALE;
+
+ if (rq_data_dir(rq) == WRITE)
+ vios = vios * fiopsd->write_scale / fiopsd->read_scale;
+
+ if (!rq_is_sync(rq))
+ vios = vios * fiopsd->async_scale / fiopsd->sync_scale;
+
+ vios += vios * (ioc->ioprio - IOPRIO_NORM) / VIOS_PRIO_SCALE;
+
+ return vios;
+}
+
+/* return vios dispatched */
+static u64 fiops_dispatch_request(struct fiops_data *fiopsd,
+ struct fiops_ioc *ioc)
+{
+ struct request *rq;
+ struct request_queue *q = fiopsd->queue;
+
+ rq = rq_entry_fifo(ioc->fifo.next);
+
+ fiops_remove_request(rq);
+ elv_dispatch_add_tail(q, rq);
+
+ fiopsd->in_flight[rq_is_sync(rq)]++;
+ ioc->in_flight++;
+
+ return fiops_scaled_vios(fiopsd, ioc, rq);
+}
+
+static int fiops_forced_dispatch(struct fiops_data *fiopsd)
+{
+ struct fiops_ioc *ioc;
+ int dispatched = 0;
+ int i;
+
+ for (i = RT_WORKLOAD; i >= IDLE_WORKLOAD; i--) {
+ while (!RB_EMPTY_ROOT(&fiopsd->service_tree[i].rb)) {
+ ioc = fiops_rb_first(&fiopsd->service_tree[i]);
+
+ while (!list_empty(&ioc->fifo)) {
+ fiops_dispatch_request(fiopsd, ioc);
+ dispatched++;
+ }
+ if (fiops_ioc_on_rr(ioc))
+ fiops_del_ioc_rr(fiopsd, ioc);
+ }
+ }
+ return dispatched;
+}
+
+static struct fiops_ioc *fiops_select_ioc(struct fiops_data *fiopsd)
+{
+ struct fiops_ioc *ioc;
+ struct fiops_rb_root *service_tree = NULL;
+ int i;
+ struct request *rq;
+
+ for (i = RT_WORKLOAD; i >= IDLE_WORKLOAD; i--) {
+ if (!RB_EMPTY_ROOT(&fiopsd->service_tree[i].rb)) {
+ service_tree = &fiopsd->service_tree[i];
+ break;
+ }
+ }
+
+ if (!service_tree)
+ return NULL;
+
+ ioc = fiops_rb_first(service_tree);
+
+ rq = rq_entry_fifo(ioc->fifo.next);
+ /*
+ * we are the only async task and sync requests are in flight, delay a
+ * moment. If there are other tasks coming, sync tasks have no chance
+ * to be starved, don't delay
+ */
+ if (!rq_is_sync(rq) && fiopsd->in_flight[1] != 0 &&
+ service_tree->count == 1) {
+ fiops_log_ioc(fiopsd, ioc,
+ "postpone async, in_flight async %d sync %d",
+ fiopsd->in_flight[0], fiopsd->in_flight[1]);
+ return NULL;
+ }
+
+ return ioc;
+}
+
+static void fiops_charge_vios(struct fiops_data *fiopsd,
+ struct fiops_ioc *ioc, u64 vios)
+{
+ struct fiops_rb_root *service_tree = ioc->service_tree;
+ ioc->vios += vios;
+
+ fiops_log_ioc(fiopsd, ioc, "charge vios %lld, new vios %lld", vios, ioc->vios);
+
+ if (RB_EMPTY_ROOT(&ioc->sort_list))
+ fiops_del_ioc_rr(fiopsd, ioc);
+ else
+ fiops_resort_rr_list(fiopsd, ioc);
+
+ fiops_update_min_vios(service_tree);
+}
+
+static int fiops_dispatch_requests(struct request_queue *q, int force)
+{
+ struct fiops_data *fiopsd = q->elevator->elevator_data;
+ struct fiops_ioc *ioc;
+ u64 vios;
+
+ if (unlikely(force))
+ return fiops_forced_dispatch(fiopsd);
+
+ ioc = fiops_select_ioc(fiopsd);
+ if (!ioc)
+ return 0;
+
+ vios = fiops_dispatch_request(fiopsd, ioc);
+
+ fiops_charge_vios(fiopsd, ioc, vios);
+ return 1;
+}
+
+static void fiops_init_prio_data(struct fiops_ioc *cic)
+{
+ struct task_struct *tsk = current;
+ struct io_context *ioc = cic->icq.ioc;
+ int ioprio_class;
+
+ if (!fiops_ioc_prio_changed(cic))
+ return;
+
+ ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio);
+ switch (ioprio_class) {
+ default:
+ printk(KERN_ERR "fiops: bad prio %x\n", ioprio_class);
+ case IOPRIO_CLASS_NONE:
+ /*
+ * no prio set, inherit CPU scheduling settings
+ */
+ cic->ioprio = task_nice_ioprio(tsk);
+ cic->wl_type = fiops_wl_type(task_nice_ioclass(tsk));
+ break;
+ case IOPRIO_CLASS_RT:
+ cic->ioprio = task_ioprio(ioc);
+ cic->wl_type = fiops_wl_type(IOPRIO_CLASS_RT);
+ break;
+ case IOPRIO_CLASS_BE:
+ cic->ioprio = task_ioprio(ioc);
+ cic->wl_type = fiops_wl_type(IOPRIO_CLASS_BE);
+ break;
+ case IOPRIO_CLASS_IDLE:
+ cic->wl_type = fiops_wl_type(IOPRIO_CLASS_IDLE);
+ cic->ioprio = 7;
+ break;
+ }
+
+ fiops_clear_ioc_prio_changed(cic);
+}
+
+static void fiops_insert_request(struct request_queue *q, struct request *rq)
+{
+ struct fiops_ioc *ioc = RQ_CIC(rq);
+
+ fiops_init_prio_data(ioc);
+
+ list_add_tail(&rq->queuelist, &ioc->fifo);
+
+ fiops_add_rq_rb(rq);
+}
+
+/*
+ * scheduler run of queue, if there are requests pending and no one in the
+ * driver that will restart queueing
+ */
+static inline void fiops_schedule_dispatch(struct fiops_data *fiopsd)
+{
+ if (fiopsd->busy_queues)
+ kblockd_schedule_work(fiopsd->queue, &fiopsd->unplug_work);
+}
+
+static void fiops_completed_request(struct request_queue *q, struct request *rq)
+{
+ struct fiops_data *fiopsd = q->elevator->elevator_data;
+ struct fiops_ioc *ioc = RQ_CIC(rq);
+
+ fiopsd->in_flight[rq_is_sync(rq)]--;
+ ioc->in_flight--;
+
+ fiops_log_ioc(fiopsd, ioc, "in_flight %d, busy queues %d",
+ ioc->in_flight, fiopsd->busy_queues);
+
+ if (fiopsd->in_flight[0] + fiopsd->in_flight[1] == 0)
+ fiops_schedule_dispatch(fiopsd);
+}
+
+static struct request *
+fiops_find_rq_fmerge(struct fiops_data *fiopsd, struct bio *bio)
+{
+ struct task_struct *tsk = current;
+ struct fiops_ioc *cic;
+
+ cic = fiops_cic_lookup(fiopsd, tsk->io_context);
+
+ if (cic) {
+ sector_t sector = bio->bi_sector + bio_sectors(bio);
+
+ return elv_rb_find(&cic->sort_list, sector);
+ }
+
+ return NULL;
+}
+
+static int fiops_merge(struct request_queue *q, struct request **req,
+ struct bio *bio)
+{
+ struct fiops_data *fiopsd = q->elevator->elevator_data;
+ struct request *__rq;
+
+ __rq = fiops_find_rq_fmerge(fiopsd, bio);
+ if (__rq && elv_rq_merge_ok(__rq, bio)) {
+ *req = __rq;
+ return ELEVATOR_FRONT_MERGE;
+ }
+
+ return ELEVATOR_NO_MERGE;
+}
+
+static void fiops_merged_request(struct request_queue *q, struct request *req,
+ int type)
+{
+ if (type == ELEVATOR_FRONT_MERGE) {
+ struct fiops_ioc *ioc = RQ_CIC(req);
+
+ fiops_reposition_rq_rb(ioc, req);
+ }
+}
+
+static void
+fiops_merged_requests(struct request_queue *q, struct request *rq,
+ struct request *next)
+{
+ struct fiops_ioc *ioc = RQ_CIC(rq);
+ struct fiops_data *fiopsd = q->elevator->elevator_data;
+
+ fiops_remove_request(next);
+
+ ioc = RQ_CIC(next);
+ /*
+ * all requests of this task are merged to other tasks, delete it
+ * from the service tree.
+ */
+ if (fiops_ioc_on_rr(ioc) && RB_EMPTY_ROOT(&ioc->sort_list))
+ fiops_del_ioc_rr(fiopsd, ioc);
+}
+
+static int fiops_allow_merge(struct request_queue *q, struct request *rq,
+ struct bio *bio)
+{
+ struct fiops_data *fiopsd = q->elevator->elevator_data;
+ struct fiops_ioc *cic;
+
+ /*
+ * Lookup the ioc that this bio will be queued with. Allow
+ * merge only if rq is queued there.
+ */
+ cic = fiops_cic_lookup(fiopsd, current->io_context);
+
+ return cic == RQ_CIC(rq);
+}
+
+static void fiops_exit_queue(struct elevator_queue *e)
+{
+ struct fiops_data *fiopsd = e->elevator_data;
+
+ cancel_work_sync(&fiopsd->unplug_work);
+
+ kfree(fiopsd);
+}
+
+static void fiops_kick_queue(struct work_struct *work)
+{
+ struct fiops_data *fiopsd =
+ container_of(work, struct fiops_data, unplug_work);
+ struct request_queue *q = fiopsd->queue;
+
+ spin_lock_irq(q->queue_lock);
+ __blk_run_queue(q);
+ spin_unlock_irq(q->queue_lock);
+}
+
+static void *fiops_init_queue(struct request_queue *q)
+{
+ struct fiops_data *fiopsd;
+ int i;
+
+ fiopsd = kzalloc_node(sizeof(*fiopsd), GFP_KERNEL, q->node);
+ if (!fiopsd)
+ return NULL;
+
+ fiopsd->queue = q;
+
+ for (i = IDLE_WORKLOAD; i <= RT_WORKLOAD; i++)
+ fiopsd->service_tree[i] = FIOPS_RB_ROOT;
+
+ INIT_WORK(&fiopsd->unplug_work, fiops_kick_queue);
+
+ fiopsd->read_scale = VIOS_READ_SCALE;
+ fiopsd->write_scale = VIOS_WRITE_SCALE;
+ fiopsd->sync_scale = VIOS_SYNC_SCALE;
+ fiopsd->async_scale = VIOS_ASYNC_SCALE;
+
+ return fiopsd;
+}
+
+static void fiops_init_icq(struct io_cq *icq)
+{
+ struct fiops_data *fiopsd = icq->q->elevator->elevator_data;
+ struct fiops_ioc *ioc = icq_to_cic(icq);
+
+ RB_CLEAR_NODE(&ioc->rb_node);
+ INIT_LIST_HEAD(&ioc->fifo);
+ ioc->sort_list = RB_ROOT;
+
+ ioc->fiopsd = fiopsd;
+
+ ioc->pid = current->pid;
+ fiops_mark_ioc_prio_changed(ioc);
+}
+
+/*
+ * sysfs parts below -->
+ */
+static ssize_t
+fiops_var_show(unsigned int var, char *page)
+{
+ return sprintf(page, "%d\n", var);
+}
+
+static ssize_t
+fiops_var_store(unsigned int *var, const char *page, size_t count)
+{
+ char *p = (char *) page;
+
+ *var = simple_strtoul(p, &p, 10);
+ return count;
+}
+
+#define SHOW_FUNCTION(__FUNC, __VAR) \
+static ssize_t __FUNC(struct elevator_queue *e, char *page) \
+{ \
+ struct fiops_data *fiopsd = e->elevator_data; \
+ return fiops_var_show(__VAR, (page)); \
+}
+SHOW_FUNCTION(fiops_read_scale_show, fiopsd->read_scale);
+SHOW_FUNCTION(fiops_write_scale_show, fiopsd->write_scale);
+SHOW_FUNCTION(fiops_sync_scale_show, fiopsd->sync_scale);
+SHOW_FUNCTION(fiops_async_scale_show, fiopsd->async_scale);
+#undef SHOW_FUNCTION
+
+#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX) \
+static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
+{ \
+ struct fiops_data *fiopsd = e->elevator_data; \
+ unsigned int __data; \
+ int ret = fiops_var_store(&__data, (page), count); \
+ if (__data < (MIN)) \
+ __data = (MIN); \
+ else if (__data > (MAX)) \
+ __data = (MAX); \
+ *(__PTR) = __data; \
+ return ret; \
+}
+STORE_FUNCTION(fiops_read_scale_store, &fiopsd->read_scale, 1, 100);
+STORE_FUNCTION(fiops_write_scale_store, &fiopsd->write_scale, 1, 100);
+STORE_FUNCTION(fiops_sync_scale_store, &fiopsd->sync_scale, 1, 100);
+STORE_FUNCTION(fiops_async_scale_store, &fiopsd->async_scale, 1, 100);
+#undef STORE_FUNCTION
+
+#define FIOPS_ATTR(name) \
+ __ATTR(name, S_IRUGO|S_IWUSR, fiops_##name##_show, fiops_##name##_store)
+
+static struct elv_fs_entry fiops_attrs[] = {
+ FIOPS_ATTR(read_scale),
+ FIOPS_ATTR(write_scale),
+ FIOPS_ATTR(sync_scale),
+ FIOPS_ATTR(async_scale),
+ __ATTR_NULL
+};
+
+static struct elevator_type iosched_fiops = {
+ .ops = {
+ .elevator_merge_fn = fiops_merge,
+ .elevator_merged_fn = fiops_merged_request,
+ .elevator_merge_req_fn = fiops_merged_requests,
+ .elevator_allow_merge_fn = fiops_allow_merge,
+ .elevator_dispatch_fn = fiops_dispatch_requests,
+ .elevator_add_req_fn = fiops_insert_request,
+ .elevator_completed_req_fn = fiops_completed_request,
+ .elevator_former_req_fn = elv_rb_former_request,
+ .elevator_latter_req_fn = elv_rb_latter_request,
+ .elevator_init_icq_fn = fiops_init_icq,
+ .elevator_init_fn = fiops_init_queue,
+ .elevator_exit_fn = fiops_exit_queue,
+ },
+ .icq_size = sizeof(struct fiops_ioc),
+ .icq_align = __alignof__(struct fiops_ioc),
+ .elevator_attrs = fiops_attrs,
+ .elevator_name = "fiops",
+ .elevator_owner = THIS_MODULE,
+};
+
+static int __init fiops_init(void)
+{
+ return elv_register(&iosched_fiops);
+}
+
+static void __exit fiops_exit(void)
+{
+ elv_unregister(&iosched_fiops);
+}
+
+module_init(fiops_init);
+module_exit(fiops_exit);
+
+MODULE_AUTHOR("Jens Axboe, Shaohua Li <shli@kernel.org>");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("IOPS based IO scheduler");
diff --git a/block/sio-iosched.c b/block/sio-iosched.c
new file mode 100644
index 0000000..3661a9a
--- /dev/null
+++ b/block/sio-iosched.c
@@ -0,0 +1,403 @@
+/*
+ * Simple IO scheduler
+ * Based on Noop, Deadline and V(R) IO schedulers.
+ *
+ * Copyright (C) 2012 Miguel Boton <mboton@gmail.com>
+ *
+ *
+ * This algorithm does not do any kind of sorting, as it is aimed for
+ * aleatory access devices, but it does some basic merging. We try to
+ * keep minimum overhead to achieve low latency.
+ *
+ * Asynchronous and synchronous requests are not treated separately, but
+ * we relay on deadlines to ensure fairness.
+ *
+ */
+#include <linux/blkdev.h>
+#include <linux/elevator.h>
+#include <linux/bio.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/version.h>
+
+enum { ASYNC, SYNC };
+
+/* Tunables */
+static const int sync_read_expire = HZ / 2; /* max time before a sync read is submitted. */
+static const int sync_write_expire = 2 * HZ; /* max time before a sync write is submitted. */
+
+static const int async_read_expire = 4 * HZ; /* ditto for async, these limits are SOFT! */
+static const int async_write_expire = 16 * HZ; /* ditto for async, these limits are SOFT! */
+
+static const int writes_starved = 2; /* max times reads can starve a write */
+static const int fifo_batch = 8; /* # of sequential requests treated as one
+ by the above parameters. For throughput. */
+
+/* Elevator data */
+struct sio_data {
+ /* Request queues */
+ struct list_head fifo_list[2][2];
+
+ /* Attributes */
+ unsigned int batched;
+ unsigned int starved;
+
+ /* Settings */
+ int fifo_expire[2][2];
+ int fifo_batch;
+ int writes_starved;
+};
+
+static void
+sio_merged_requests(struct request_queue *q, struct request *rq,
+ struct request *next)
+{
+ /*
+ * If next expires before rq, assign its expire time to rq
+ * and move into next position (next will be deleted) in fifo.
+ */
+ if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist)) {
+ if (time_before(rq_fifo_time(next), rq_fifo_time(rq))) {
+ list_move(&rq->queuelist, &next->queuelist);
+ rq_set_fifo_time(rq, rq_fifo_time(next));
+ }
+ }
+
+ /* Delete next request */
+ rq_fifo_clear(next);
+}
+
+static void
+sio_add_request(struct request_queue *q, struct request *rq)
+{
+ struct sio_data *sd = q->elevator->elevator_data;
+ const int sync = rq_is_sync(rq);
+ const int data_dir = rq_data_dir(rq);
+
+ /*
+ * Add request to the proper fifo list and set its
+ * expire time.
+ */
+ rq_set_fifo_time(rq, jiffies + sd->fifo_expire[sync][data_dir]);
+ list_add_tail(&rq->queuelist, &sd->fifo_list[sync][data_dir]);
+}
+
+#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,38)
+static int
+sio_queue_empty(struct request_queue *q)
+{
+ struct sio_data *sd = q->elevator->elevator_data;
+
+ /* Check if fifo lists are empty */
+ return list_empty(&sd->fifo_list[SYNC][READ]) && list_empty(&sd->fifo_list[SYNC][WRITE]) &&
+ list_empty(&sd->fifo_list[ASYNC][READ]) && list_empty(&sd->fifo_list[ASYNC][WRITE]);
+}
+#endif
+
+static struct request *
+sio_expired_request(struct sio_data *sd, int sync, int data_dir)
+{
+ struct list_head *list = &sd->fifo_list[sync][data_dir];
+ struct request *rq;
+
+ if (list_empty(list))
+ return NULL;
+
+ /* Retrieve request */
+ rq = rq_entry_fifo(list->next);
+
+ /* Request has expired */
+ if (time_after(jiffies, rq_fifo_time(rq)))
+ return rq;
+
+ return NULL;
+}
+
+static struct request *
+sio_choose_expired_request(struct sio_data *sd)
+{
+ struct request *rq;
+
+ /*
+ * Check expired requests.
+ * Asynchronous requests have priority over synchronous.
+ * Write requests have priority over read.
+ */
+ rq = sio_expired_request(sd, ASYNC, WRITE);
+ if (rq)
+ return rq;
+ rq = sio_expired_request(sd, ASYNC, READ);
+ if (rq)
+ return rq;
+
+ rq = sio_expired_request(sd, SYNC, WRITE);
+ if (rq)
+ return rq;
+ rq = sio_expired_request(sd, SYNC, READ);
+ if (rq)
+ return rq;
+
+ return NULL;
+}
+
+static struct request *
+sio_choose_request(struct sio_data *sd, int data_dir)
+{
+ struct list_head *sync = sd->fifo_list[SYNC];
+ struct list_head *async = sd->fifo_list[ASYNC];
+
+ /*
+ * Retrieve request from available fifo list.
+ * Synchronous requests have priority over asynchronous.
+ * Read requests have priority over write.
+ */
+ if (!list_empty(&sync[data_dir]))
+ return rq_entry_fifo(sync[data_dir].next);
+ if (!list_empty(&async[data_dir]))
+ return rq_entry_fifo(async[data_dir].next);
+
+ if (!list_empty(&sync[!data_dir]))
+ return rq_entry_fifo(sync[!data_dir].next);
+ if (!list_empty(&async[!data_dir]))
+ return rq_entry_fifo(async[!data_dir].next);
+
+ return NULL;
+}
+
+static inline void
+sio_dispatch_request(struct sio_data *sd, struct request *rq)
+{
+ /*
+ * Remove the request from the fifo list
+ * and dispatch it.
+ */
+ rq_fifo_clear(rq);
+ elv_dispatch_add_tail(rq->q, rq);
+
+ sd->batched++;
+
+ if (rq_data_dir(rq))
+ sd->starved = 0;
+ else
+ sd->starved++;
+}
+
+static int
+sio_dispatch_requests(struct request_queue *q, int force)
+{
+ struct sio_data *sd = q->elevator->elevator_data;
+ struct request *rq = NULL;
+ int data_dir = READ;
+
+ /*
+ * Retrieve any expired request after a batch of
+ * sequential requests.
+ */
+ if (sd->batched > sd->fifo_batch) {
+ sd->batched = 0;
+ rq = sio_choose_expired_request(sd);
+ }
+
+ /* Retrieve request */
+ if (!rq) {
+ if (sd->starved > sd->writes_starved)
+ data_dir = WRITE;
+
+ rq = sio_choose_request(sd, data_dir);
+ if (!rq)
+ return 0;
+ }
+
+ /* Dispatch request */
+ sio_dispatch_request(sd, rq);
+
+ return 1;
+}
+
+static struct request *
+sio_former_request(struct request_queue *q, struct request *rq)
+{
+ struct sio_data *sd = q->elevator->elevator_data;
+ const int sync = rq_is_sync(rq);
+ const int data_dir = rq_data_dir(rq);
+
+ if (rq->queuelist.prev == &sd->fifo_list[sync][data_dir])
+ return NULL;
+
+ /* Return former request */
+ return list_entry(rq->queuelist.prev, struct request, queuelist);
+}
+
+static struct request *
+sio_latter_request(struct request_queue *q, struct request *rq)
+{
+ struct sio_data *sd = q->elevator->elevator_data;
+ const int sync = rq_is_sync(rq);
+ const int data_dir = rq_data_dir(rq);
+
+ if (rq->queuelist.next == &sd->fifo_list[sync][data_dir])
+ return NULL;
+
+ /* Return latter request */
+ return list_entry(rq->queuelist.next, struct request, queuelist);
+}
+
+static void *
+sio_init_queue(struct request_queue *q)
+{
+ struct sio_data *sd;
+
+ /* Allocate structure */
+ sd = kmalloc_node(sizeof(*sd), GFP_KERNEL, q->node);
+ if (!sd)
+ return NULL;
+
+ /* Initialize fifo lists */
+ INIT_LIST_HEAD(&sd->fifo_list[SYNC][READ]);
+ INIT_LIST_HEAD(&sd->fifo_list[SYNC][WRITE]);
+ INIT_LIST_HEAD(&sd->fifo_list[ASYNC][READ]);
+ INIT_LIST_HEAD(&sd->fifo_list[ASYNC][WRITE]);
+
+ /* Initialize data */
+ sd->batched = 0;
+ sd->fifo_expire[SYNC][READ] = sync_read_expire;
+ sd->fifo_expire[SYNC][WRITE] = sync_write_expire;
+ sd->fifo_expire[ASYNC][READ] = async_read_expire;
+ sd->fifo_expire[ASYNC][WRITE] = async_write_expire;
+ sd->fifo_batch = fifo_batch;
+
+ return sd;
+}
+
+static void
+sio_exit_queue(struct elevator_queue *e)
+{
+ struct sio_data *sd = e->elevator_data;
+
+ BUG_ON(!list_empty(&sd->fifo_list[SYNC][READ]));
+ BUG_ON(!list_empty(&sd->fifo_list[SYNC][WRITE]));
+ BUG_ON(!list_empty(&sd->fifo_list[ASYNC][READ]));
+ BUG_ON(!list_empty(&sd->fifo_list[ASYNC][WRITE]));
+
+ /* Free structure */
+ kfree(sd);
+}
+
+/*
+ * sysfs code
+ */
+
+static ssize_t
+sio_var_show(int var, char *page)
+{
+ return sprintf(page, "%d\n", var);
+}
+
+static ssize_t
+sio_var_store(int *var, const char *page, size_t count)
+{
+ char *p = (char *) page;
+
+ *var = simple_strtol(p, &p, 10);
+ return count;
+}
+
+#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
+static ssize_t __FUNC(struct elevator_queue *e, char *page) \
+{ \
+ struct sio_data *sd = e->elevator_data; \
+ int __data = __VAR; \
+ if (__CONV) \
+ __data = jiffies_to_msecs(__data); \
+ return sio_var_show(__data, (page)); \
+}
+SHOW_FUNCTION(sio_sync_read_expire_show, sd->fifo_expire[SYNC][READ], 1);
+SHOW_FUNCTION(sio_sync_write_expire_show, sd->fifo_expire[SYNC][WRITE], 1);
+SHOW_FUNCTION(sio_async_read_expire_show, sd->fifo_expire[ASYNC][READ], 1);
+SHOW_FUNCTION(sio_async_write_expire_show, sd->fifo_expire[ASYNC][WRITE], 1);
+SHOW_FUNCTION(sio_fifo_batch_show, sd->fifo_batch, 0);
+SHOW_FUNCTION(sio_writes_starved_show, sd->writes_starved, 0);
+#undef SHOW_FUNCTION
+
+#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
+static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
+{ \
+ struct sio_data *sd = e->elevator_data; \
+ int __data; \
+ int ret = sio_var_store(&__data, (page), count); \
+ if (__data < (MIN)) \
+ __data = (MIN); \
+ else if (__data > (MAX)) \
+ __data = (MAX); \
+ if (__CONV) \
+ *(__PTR) = msecs_to_jiffies(__data); \
+ else \
+ *(__PTR) = __data; \
+ return ret; \
+}
+STORE_FUNCTION(sio_sync_read_expire_store, &sd->fifo_expire[SYNC][READ], 0, INT_MAX, 1);
+STORE_FUNCTION(sio_sync_write_expire_store, &sd->fifo_expire[SYNC][WRITE], 0, INT_MAX, 1);
+STORE_FUNCTION(sio_async_read_expire_store, &sd->fifo_expire[ASYNC][READ], 0, INT_MAX, 1);
+STORE_FUNCTION(sio_async_write_expire_store, &sd->fifo_expire[ASYNC][WRITE], 0, INT_MAX, 1);
+STORE_FUNCTION(sio_fifo_batch_store, &sd->fifo_batch, 0, INT_MAX, 0);
+STORE_FUNCTION(sio_writes_starved_store, &sd->writes_starved, 0, INT_MAX, 0);
+#undef STORE_FUNCTION
+
+#define DD_ATTR(name) \
+ __ATTR(name, S_IRUGO|S_IWUSR, sio_##name##_show, \
+ sio_##name##_store)
+
+static struct elv_fs_entry sio_attrs[] = {
+ DD_ATTR(sync_read_expire),
+ DD_ATTR(sync_write_expire),
+ DD_ATTR(async_read_expire),
+ DD_ATTR(async_write_expire),
+ DD_ATTR(fifo_batch),
+ DD_ATTR(writes_starved),
+ __ATTR_NULL
+};
+
+static struct elevator_type iosched_sio = {
+ .ops = {
+ .elevator_merge_req_fn = sio_merged_requests,
+ .elevator_dispatch_fn = sio_dispatch_requests,
+ .elevator_add_req_fn = sio_add_request,
+#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,38)
+ .elevator_queue_empty_fn = sio_queue_empty,
+#endif
+ .elevator_former_req_fn = sio_former_request,
+ .elevator_latter_req_fn = sio_latter_request,
+ .elevator_init_fn = sio_init_queue,
+ .elevator_exit_fn = sio_exit_queue,
+ },
+
+ .elevator_attrs = sio_attrs,
+ .elevator_name = "sio",
+ .elevator_owner = THIS_MODULE,
+};
+
+static int __init sio_init(void)
+{
+ /* Register elevator */
+ elv_register(&iosched_sio);
+
+ return 0;
+}
+
+static void __exit sio_exit(void)
+{
+ /* Unregister elevator */
+ elv_unregister(&iosched_sio);
+}
+
+#ifdef CONFIG_FAST_RESUME
+beforeresume_initcall(sio_init);
+#else
+module_init(sio_init);
+#endif
+module_exit(sio_exit);
+
+MODULE_AUTHOR("Miguel Boton");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Simple IO scheduler");
+MODULE_VERSION("0.2");
diff --git a/block/sioplus-iosched.c b/block/sioplus-iosched.c
new file mode 100644
index 0000000..6809cb8
--- /dev/null
+++ b/block/sioplus-iosched.c
@@ -0,0 +1,405 @@
+/*
+ * Simple IO scheduler plus
+ * Based on Noop, Deadline and V(R) IO schedulers.
+ *
+ * Copyright (C) 2012 Miguel Boton <mboton@gmail.com>
+ * (C) 2013, 2014 Boy Petersen <boypetersen@gmail.com>
+ *
+ *
+ * This algorithm does not do any kind of sorting, as it is aimed for
+ * aleatory access devices, but it does some basic merging. We try to
+ * keep minimum overhead to achieve low latency.
+ *
+ * Asynchronous and synchronous requests are not treated separately, but
+ * we relay on deadlines to ensure fairness.
+ *
+ * The plus version incorporates several fixes and logic improvements.
+ *
+ */
+#include <linux/blkdev.h>
+#include <linux/elevator.h>
+#include <linux/bio.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+
+enum { ASYNC, SYNC };
+
+/* Tunables */
+static const int sync_read_expire = (HZ / 4); /* max time before a sync read is submitted. */
+static const int sync_write_expire = (HZ / 4) * 5; /* max time before a sync write is submitted. */
+
+static const int async_read_expire = (HZ / 2); /* ditto for async, these limits are SOFT! */
+static const int async_write_expire = (HZ * 2); /* ditto for async, these limits are SOFT! */
+
+static const int writes_starved = 1; /* max times reads can starve a write */
+static const int fifo_batch = 3; /* # of sequential requests treated as one
+ by the above parameters. For throughput. */
+
+/* Elevator data */
+struct sio_data {
+ /* Request queues */
+ struct list_head fifo_list[2][2];
+
+ /* Attributes */
+ unsigned int batched;
+ unsigned int starved;
+
+ /* Settings */
+ int fifo_expire[2][2];
+ int fifo_batch;
+ int writes_starved;
+};
+
+static void
+sio_merged_requests(struct request_queue *q, struct request *rq,
+ struct request *next)
+{
+ /*
+ * If next expires before rq, assign its expire time to rq
+ * and move into next position (next will be deleted) in fifo.
+ */
+ if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist)) {
+ if (time_before(rq_fifo_time(next), rq_fifo_time(rq))) {
+ list_move(&rq->queuelist, &next->queuelist);
+ rq_set_fifo_time(rq, rq_fifo_time(next));
+ }
+ }
+
+ /* Delete next request */
+ rq_fifo_clear(next);
+}
+
+static void
+sio_add_request(struct request_queue *q, struct request *rq)
+{
+ struct sio_data *sd = q->elevator->elevator_data;
+ const int sync = rq_is_sync(rq);
+ const int data_dir = rq_data_dir(rq);
+
+ /*
+ * Add request to the proper fifo list and set its
+ * expire time.
+ */
+ rq_set_fifo_time(rq, jiffies + sd->fifo_expire[sync][data_dir]);
+ list_add_tail(&rq->queuelist, &sd->fifo_list[sync][data_dir]);
+}
+
+static int
+sio_queue_empty(struct request_queue *q)
+{
+ struct sio_data *sd = q->elevator->elevator_data;
+
+ /* Check if fifo lists are empty */
+ return list_empty(&sd->fifo_list[SYNC][READ]) && list_empty(&sd->fifo_list[SYNC][WRITE]) &&
+ list_empty(&sd->fifo_list[ASYNC][READ]) && list_empty(&sd->fifo_list[ASYNC][WRITE]);
+}
+
+static struct request *
+sio_expired_request(struct sio_data *sd, int sync, int data_dir)
+{
+ struct list_head *list = &sd->fifo_list[sync][data_dir];
+ struct request *rq;
+
+ if (list_empty(list))
+ return NULL;
+
+ /* Retrieve request */
+ rq = rq_entry_fifo(list->next);
+
+ /* Request has expired */
+ if (time_after_eq(jiffies, rq_fifo_time(rq)))
+ return rq;
+
+ return NULL;
+}
+
+static struct request *
+sio_choose_expired_request(struct sio_data *sd)
+{
+ struct request *rq;
+
+ /* Reset (non-expired-)batch-counter */
+ sd->batched = 0;
+
+ /*
+ * Check expired requests.
+ * Asynchronous requests have priority over synchronous.
+ * Write requests have priority over read.
+ */
+ rq = sio_expired_request(sd, ASYNC, WRITE);
+ if (rq)
+ return rq;
+ rq = sio_expired_request(sd, ASYNC, READ);
+ if (rq)
+ return rq;
+
+ rq = sio_expired_request(sd, SYNC, WRITE);
+ if (rq)
+ return rq;
+ rq = sio_expired_request(sd, SYNC, READ);
+ if (rq)
+ return rq;
+
+
+ return NULL;
+}
+
+static struct request *
+sio_choose_request(struct sio_data *sd, int data_dir)
+{
+ struct list_head *sync = sd->fifo_list[SYNC];
+ struct list_head *async = sd->fifo_list[ASYNC];
+
+ /* Increase (non-expired-)batch-counter */
+ sd->batched++;
+
+ /*
+ * Retrieve request from available fifo list.
+ * Synchronous requests have priority over asynchronous.
+ * Read requests have priority over write.
+ */
+ if (!list_empty(&sync[data_dir]))
+ return rq_entry_fifo(sync[data_dir].next);
+ if (!list_empty(&async[data_dir]))
+ return rq_entry_fifo(async[data_dir].next);
+
+ if (!list_empty(&sync[!data_dir]))
+ return rq_entry_fifo(sync[!data_dir].next);
+ if (!list_empty(&async[!data_dir]))
+ return rq_entry_fifo(async[!data_dir].next);
+
+ return NULL;
+}
+
+static inline void
+sio_dispatch_request(struct sio_data *sd, struct request *rq)
+{
+
+ /*
+ * Remove the request from the fifo list
+ * and dispatch it.
+ */
+ rq_fifo_clear(rq);
+ elv_dispatch_add_tail(rq->q, rq);
+
+ if (rq_data_dir(rq)) {
+ sd->starved = 0;
+ } else {
+ if (!list_empty(&sd->fifo_list[SYNC][WRITE]) ||
+ !list_empty(&sd->fifo_list[ASYNC][WRITE]))
+ sd->starved++;
+ }
+}
+
+static int
+sio_dispatch_requests(struct request_queue *q, int force)
+{
+ struct sio_data *sd = q->elevator->elevator_data;
+ struct request *rq = NULL;
+ int data_dir = READ;
+
+ /*
+ * Retrieve any expired request after a batch of
+ * sequential requests.
+ */
+ if (sd->batched >= sd->fifo_batch)
+ rq = sio_choose_expired_request(sd);
+
+ /* Retrieve request */
+ if (!rq) {
+ if (sd->starved >= sd->writes_starved)
+ data_dir = WRITE;
+
+ rq = sio_choose_request(sd, data_dir);
+ if (!rq)
+ return 0;
+ }
+
+ /* Dispatch request */
+ sio_dispatch_request(sd, rq);
+
+ return 1;
+}
+
+static struct request *
+sio_former_request(struct request_queue *q, struct request *rq)
+{
+ struct sio_data *sd = q->elevator->elevator_data;
+ const int sync = rq_is_sync(rq);
+ const int data_dir = rq_data_dir(rq);
+
+ if (rq->queuelist.prev == &sd->fifo_list[sync][data_dir])
+ return NULL;
+
+ /* Return former request */
+ return list_entry(rq->queuelist.prev, struct request, queuelist);
+}
+
+static struct request *
+sio_latter_request(struct request_queue *q, struct request *rq)
+{
+ struct sio_data *sd = q->elevator->elevator_data;
+ const int sync = rq_is_sync(rq);
+ const int data_dir = rq_data_dir(rq);
+
+ if (rq->queuelist.next == &sd->fifo_list[sync][data_dir])
+ return NULL;
+
+ /* Return latter request */
+ return list_entry(rq->queuelist.next, struct request, queuelist);
+}
+
+static void *
+sio_init_queue(struct request_queue *q)
+{
+ struct sio_data *sd;
+
+ /* Allocate structure */
+ sd = kmalloc_node(sizeof(*sd), GFP_KERNEL, q->node);
+ if (!sd)
+ return NULL;
+
+ /* Initialize fifo lists */
+ INIT_LIST_HEAD(&sd->fifo_list[SYNC][READ]);
+ INIT_LIST_HEAD(&sd->fifo_list[SYNC][WRITE]);
+ INIT_LIST_HEAD(&sd->fifo_list[ASYNC][READ]);
+ INIT_LIST_HEAD(&sd->fifo_list[ASYNC][WRITE]);
+
+ /* Initialize data */
+ sd->batched = 0;
+ sd->fifo_expire[SYNC][READ] = sync_read_expire;
+ sd->fifo_expire[SYNC][WRITE] = sync_write_expire;
+ sd->fifo_expire[ASYNC][READ] = async_read_expire;
+ sd->fifo_expire[ASYNC][WRITE] = async_write_expire;
+ sd->fifo_batch = fifo_batch;
+ sd->writes_starved = writes_starved;
+
+ return sd;
+}
+
+static void
+sio_exit_queue(struct elevator_queue *e)
+{
+ struct sio_data *sd = e->elevator_data;
+
+ BUG_ON(!list_empty(&sd->fifo_list[SYNC][READ]));
+ BUG_ON(!list_empty(&sd->fifo_list[SYNC][WRITE]));
+ BUG_ON(!list_empty(&sd->fifo_list[ASYNC][READ]));
+ BUG_ON(!list_empty(&sd->fifo_list[ASYNC][WRITE]));
+
+ /* Free structure */
+ kfree(sd);
+}
+
+/*
+ * sysfs code
+ */
+
+static ssize_t
+sio_var_show(int var, char *page)
+{
+ return sprintf(page, "%d\n", var);
+}
+
+static ssize_t
+sio_var_store(int *var, const char *page, size_t count)
+{
+ char *p = (char *) page;
+
+ *var = simple_strtol(p, &p, 10);
+ return count;
+}
+
+#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
+static ssize_t __FUNC(struct elevator_queue *e, char *page) \
+{ \
+ struct sio_data *sd = e->elevator_data; \
+ int __data = __VAR; \
+ if (__CONV) \
+ __data = jiffies_to_msecs(__data); \
+ return sio_var_show(__data, (page)); \
+}
+SHOW_FUNCTION(sio_sync_read_expire_show, sd->fifo_expire[SYNC][READ], 1);
+SHOW_FUNCTION(sio_sync_write_expire_show, sd->fifo_expire[SYNC][WRITE], 1);
+SHOW_FUNCTION(sio_async_read_expire_show, sd->fifo_expire[ASYNC][READ], 1);
+SHOW_FUNCTION(sio_async_write_expire_show, sd->fifo_expire[ASYNC][WRITE], 1);
+SHOW_FUNCTION(sio_fifo_batch_show, sd->fifo_batch, 0);
+SHOW_FUNCTION(sio_writes_starved_show, sd->writes_starved, 0);
+#undef SHOW_FUNCTION
+
+#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
+static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
+{ \
+ struct sio_data *sd = e->elevator_data; \
+ int __data; \
+ int ret = sio_var_store(&__data, (page), count); \
+ if (__data < (MIN)) \
+ __data = (MIN); \
+ else if (__data > (MAX)) \
+ __data = (MAX); \
+ if (__CONV) \
+ *(__PTR) = msecs_to_jiffies(__data); \
+ else \
+ *(__PTR) = __data; \
+ return ret; \
+}
+STORE_FUNCTION(sio_sync_read_expire_store, &sd->fifo_expire[SYNC][READ], 0, INT_MAX, 1);
+STORE_FUNCTION(sio_sync_write_expire_store, &sd->fifo_expire[SYNC][WRITE], 0, INT_MAX, 1);
+STORE_FUNCTION(sio_async_read_expire_store, &sd->fifo_expire[ASYNC][READ], 0, INT_MAX, 1);
+STORE_FUNCTION(sio_async_write_expire_store, &sd->fifo_expire[ASYNC][WRITE], 0, INT_MAX, 1);
+STORE_FUNCTION(sio_fifo_batch_store, &sd->fifo_batch, 1, INT_MAX, 0);
+STORE_FUNCTION(sio_writes_starved_store, &sd->writes_starved, 1, INT_MAX, 0);
+#undef STORE_FUNCTION
+
+#define DD_ATTR(name) \
+ __ATTR(name, S_IRUGO|S_IWUSR, sio_##name##_show, \
+ sio_##name##_store)
+
+static struct elv_fs_entry sio_attrs[] = {
+ DD_ATTR(sync_read_expire),
+ DD_ATTR(sync_write_expire),
+ DD_ATTR(async_read_expire),
+ DD_ATTR(async_write_expire),
+ DD_ATTR(fifo_batch),
+ DD_ATTR(writes_starved),
+ __ATTR_NULL
+};
+
+static struct elevator_type iosched_sioplus = {
+ .ops = {
+ .elevator_merge_req_fn = sio_merged_requests,
+ .elevator_dispatch_fn = sio_dispatch_requests,
+ .elevator_add_req_fn = sio_add_request,
+ .elevator_queue_empty_fn = sio_queue_empty,
+ .elevator_former_req_fn = sio_former_request,
+ .elevator_latter_req_fn = sio_latter_request,
+ .elevator_init_fn = sio_init_queue,
+ .elevator_exit_fn = sio_exit_queue,
+ },
+
+ .elevator_attrs = sio_attrs,
+ .elevator_name = "sioplus",
+ .elevator_owner = THIS_MODULE,
+};
+
+static int __init sioplus_init(void)
+{
+ /* Register elevator */
+ elv_register(&iosched_sioplus);
+
+ return 0;
+}
+
+static void __exit sioplus_exit(void)
+{
+ /* Unregister elevator */
+ elv_unregister(&iosched_sioplus);
+}
+
+module_init(sioplus_init);
+module_exit(sioplus_exit);
+
+MODULE_AUTHOR("Miguel Boton");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Simple IO scheduler plus");
diff --git a/block/tripndroid-iosched.c b/block/tripndroid-iosched.c
new file mode 100644
index 0000000..a4d0080
--- /dev/null
+++ b/block/tripndroid-iosched.c
@@ -0,0 +1,261 @@
+/*
+ * Copyright (c) 2013, TripNDroid Mobile Engineering
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#include <linux/blkdev.h>
+#include <linux/elevator.h>
+#include <linux/bio.h>
+#include <linux/module.h>
+#include <linux/init.h>
+
+enum { ASYNC, SYNC };
+
+static const int sync_read_expire = 1 * HZ; /* max time before a sync read is submitted. */
+static const int sync_write_expire = 1 * HZ; /* max time before a sync write is submitted. */
+static const int async_read_expire = 2 * HZ; /* ditto for async, these limits are SOFT! */
+static const int async_write_expire = 2 * HZ; /* ditto for async, these limits are SOFT! */
+
+static const int writes_starved = 1; /* max times reads can starve a write */
+static const int fifo_batch = 1; /* # of sequential requests treated as one
+ by the above parameters. For throughput. */
+
+struct tripndroid_data {
+
+ struct list_head fifo_list[2][2];
+
+ unsigned int batched;
+ unsigned int starved;
+
+ int fifo_expire[2][2];
+ int fifo_batch;
+ int writes_starved;
+};
+
+static void tripndroid_merged_requests(struct request_queue *q, struct request *rq,
+ struct request *next)
+{
+ /*
+ * If next expires before rq, assign its expire time to rq
+ * and move into next position (next will be deleted) in fifo.
+ */
+ if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist)) {
+ if (time_before(rq_fifo_time(next), rq_fifo_time(rq))) {
+ list_move(&rq->queuelist, &next->queuelist);
+ rq_set_fifo_time(rq, rq_fifo_time(next));
+ }
+ }
+
+ rq_fifo_clear(next);
+}
+
+static void tripndroid_add_request(struct request_queue *q, struct request *rq)
+{
+ struct tripndroid_data *td = q->elevator->elevator_data;
+ const int sync = rq_is_sync(rq);
+ const int data_dir = rq_data_dir(rq);
+
+ rq_set_fifo_time(rq, jiffies + td->fifo_expire[sync][data_dir]);
+ list_add(&rq->queuelist, &td->fifo_list[sync][data_dir]);
+}
+
+static struct request *tripndroid_expired_request(struct tripndroid_data *td, int sync, int data_dir)
+{
+ struct list_head *list = &td->fifo_list[sync][data_dir];
+ struct request *rq;
+
+ if (list_empty(list))
+ return NULL;
+
+ rq = rq_entry_fifo(list->next);
+
+ if (time_after_eq(jiffies, rq_fifo_time(rq)))
+ return rq;
+
+ return NULL;
+}
+
+static struct request *tripndroid_choose_expired_request(struct tripndroid_data *td)
+{
+ struct request *rq;
+
+ /* Asynchronous requests have priority over synchronous.
+ * Write requests have priority over read. */
+
+ rq = tripndroid_expired_request(td, ASYNC, WRITE);
+ if (rq)
+ return rq;
+ rq = tripndroid_expired_request(td, ASYNC, READ);
+ if (rq)
+ return rq;
+
+ rq = tripndroid_expired_request(td, SYNC, WRITE);
+ if (rq)
+ return rq;
+ rq = tripndroid_expired_request(td, SYNC, READ);
+ if (rq)
+ return rq;
+
+ return NULL;
+}
+
+static struct request *tripndroid_choose_request(struct tripndroid_data *td, int data_dir)
+{
+ struct list_head *sync = td->fifo_list[SYNC];
+ struct list_head *async = td->fifo_list[ASYNC];
+
+ if (!list_empty(&sync[data_dir]))
+ return rq_entry_fifo(sync[data_dir].next);
+ if (!list_empty(&sync[!data_dir]))
+ return rq_entry_fifo(sync[!data_dir].next);
+
+ if (!list_empty(&async[data_dir]))
+ return rq_entry_fifo(async[data_dir].next);
+ if (!list_empty(&async[!data_dir]))
+ return rq_entry_fifo(async[!data_dir].next);
+
+ return NULL;
+}
+
+static inline void tripndroid_dispatch_request(struct tripndroid_data *td, struct request *rq)
+{
+ /* Dispatch the request */
+ rq_fifo_clear(rq);
+ elv_dispatch_add_tail(rq->q, rq);
+
+ td->batched++;
+
+ if (rq_data_dir(rq))
+ td->starved = 0;
+ else
+ td->starved++;
+}
+
+static int tripndroid_dispatch_requests(struct request_queue *q, int force)
+{
+ struct tripndroid_data *td = q->elevator->elevator_data;
+ struct request *rq = NULL;
+ int data_dir = READ;
+
+ if (td->batched > td->fifo_batch) {
+ td->batched = 0;
+ rq = tripndroid_choose_expired_request(td);
+ }
+
+ if (!rq) {
+ if (td->starved > td->writes_starved)
+ data_dir = WRITE;
+
+ rq = tripndroid_choose_request(td, data_dir);
+ if (!rq)
+ return 0;
+ }
+
+ tripndroid_dispatch_request(td, rq);
+
+ return 1;
+}
+
+static struct request *tripndroid_former_request(struct request_queue *q, struct request *rq)
+{
+ struct tripndroid_data *td = q->elevator->elevator_data;
+ const int sync = rq_is_sync(rq);
+ const int data_dir = rq_data_dir(rq);
+
+ if (rq->queuelist.prev == &td->fifo_list[sync][data_dir])
+ return NULL;
+
+ return list_entry(rq->queuelist.prev, struct request, queuelist);
+}
+
+static struct request *tripndroid_latter_request(struct request_queue *q, struct request *rq)
+{
+ struct tripndroid_data *td = q->elevator->elevator_data;
+ const int sync = rq_is_sync(rq);
+ const int data_dir = rq_data_dir(rq);
+
+ if (rq->queuelist.next == &td->fifo_list[sync][data_dir])
+ return NULL;
+
+ return list_entry(rq->queuelist.next, struct request, queuelist);
+}
+
+static void *tripndroid_init_queue(struct request_queue *q)
+{
+ struct tripndroid_data *td;
+
+ td = kmalloc_node(sizeof(*td), GFP_KERNEL, q->node);
+ if (!td)
+ return NULL;
+
+ INIT_LIST_HEAD(&td->fifo_list[SYNC][READ]);
+ INIT_LIST_HEAD(&td->fifo_list[SYNC][WRITE]);
+ INIT_LIST_HEAD(&td->fifo_list[ASYNC][READ]);
+ INIT_LIST_HEAD(&td->fifo_list[ASYNC][WRITE]);
+
+ td->batched = 0;
+ td->fifo_expire[SYNC][READ] = sync_read_expire;
+ td->fifo_expire[SYNC][WRITE] = sync_write_expire;
+ td->fifo_expire[ASYNC][READ] = async_read_expire;
+ td->fifo_expire[ASYNC][WRITE] = async_write_expire;
+ td->fifo_batch = fifo_batch;
+
+ return td;
+}
+
+static void tripndroid_exit_queue(struct elevator_queue *e)
+{
+ struct tripndroid_data *td = e->elevator_data;
+
+ BUG_ON(!list_empty(&td->fifo_list[SYNC][READ]));
+ BUG_ON(!list_empty(&td->fifo_list[SYNC][WRITE]));
+ BUG_ON(!list_empty(&td->fifo_list[ASYNC][READ]));
+ BUG_ON(!list_empty(&td->fifo_list[ASYNC][WRITE]));
+
+ kfree(td);
+}
+
+static struct elevator_type iosched_tripndroid = {
+ .ops = {
+ .elevator_merge_req_fn = tripndroid_merged_requests,
+ .elevator_dispatch_fn = tripndroid_dispatch_requests,
+ .elevator_add_req_fn = tripndroid_add_request,
+ .elevator_former_req_fn = tripndroid_former_request,
+ .elevator_latter_req_fn = tripndroid_latter_request,
+ .elevator_init_fn = tripndroid_init_queue,
+ .elevator_exit_fn = tripndroid_exit_queue,
+ },
+ .elevator_name = "tripndroid",
+ .elevator_owner = THIS_MODULE,
+};
+
+static int __init tripndroid_init(void)
+{
+ elv_register(&iosched_tripndroid);
+ return 0;
+}
+
+static void __exit tripndroid_exit(void)
+{
+ elv_unregister(&iosched_tripndroid);
+}
+
+module_init(tripndroid_init);
+module_exit(tripndroid_exit);
+
+MODULE_AUTHOR("TripNRaVeR");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("TripNDroid IO Scheduler");
diff --git a/block/vr-iosched.c b/block/vr-iosched.c
new file mode 100644
index 0000000..5d8954b
--- /dev/null
+++ b/block/vr-iosched.c
@@ -0,0 +1,432 @@
+/*
+* V(R) I/O Scheduler
+*
+* Copyright (C) 2007 Aaron Carroll <aaronc@gelato.unsw.edu.au>
+*
+*
+* The algorithm:
+*
+* The next request is decided based on its distance from the last
+* request, with a multiplicative penalty of `rev_penalty' applied
+* for reversing the head direction. A rev_penalty of 1 means SSTF
+* behaviour. As this variable is increased, the algorithm approaches
+* pure SCAN. Setting rev_penalty to 0 forces SCAN.
+*
+* Async and synch requests are not treated seperately. Instead we
+* rely on deadlines to ensure fairness.
+*
+*/
+#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/blkdev.h>
+#include <linux/elevator.h>
+#include <linux/bio.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/compiler.h>
+#include <linux/rbtree.h>
+
+#include <asm/div64.h>
+
+enum vr_data_dir {
+ ASYNC,
+ SYNC,
+};
+
+enum vr_head_dir {
+ FORWARD,
+ BACKWARD,
+};
+
+static const int sync_expire = HZ / 2; /* max time before a sync is submitted. */
+static const int async_expire = 5 * HZ; /* ditto for async, these limits are SOFT! */
+static const int fifo_batch = 1;
+static const int rev_penalty = 10; /* penalty for reversing head direction */
+
+struct vr_data {
+struct rb_root sort_list;
+struct list_head fifo_list[2];
+
+struct request *next_rq;
+struct request *prev_rq;
+
+unsigned int nbatched;
+sector_t last_sector; /* head position */
+int head_dir;
+
+/* tunables */
+int fifo_expire[2];
+int fifo_batch;
+int rev_penalty;
+};
+
+static void vr_move_request(struct vr_data *, struct request *);
+
+static inline struct vr_data *
+vr_get_data(struct request_queue *q)
+{
+ return q->elevator->elevator_data;
+}
+
+static void
+vr_add_rq_rb(struct vr_data *vd, struct request *rq)
+{
+ elv_rb_add(&vd->sort_list, rq);
+
+ if (blk_rq_pos(rq) >= vd->last_sector) {
+ if (!vd->next_rq || blk_rq_pos(vd->next_rq) > blk_rq_pos(rq))
+ vd->next_rq = rq;
+ } else {
+ if (!vd->prev_rq || blk_rq_pos(vd->prev_rq) < blk_rq_pos(rq))
+ vd->prev_rq = rq;
+ }
+
+ BUG_ON(vd->next_rq && vd->next_rq == vd->prev_rq);
+ BUG_ON(vd->next_rq && vd->prev_rq && blk_rq_pos(vd->next_rq) < blk_rq_pos(vd->prev_rq));
+}
+
+static void
+vr_del_rq_rb(struct vr_data *vd, struct request *rq)
+{
+ /*
+ * We might be deleting our cached next request.
+ * If so, find its sucessor.
+ */
+
+ if (vd->next_rq == rq)
+ vd->next_rq = elv_rb_latter_request(NULL, rq);
+ else if (vd->prev_rq == rq)
+ vd->prev_rq = elv_rb_former_request(NULL, rq);
+
+ BUG_ON(vd->next_rq && vd->next_rq == vd->prev_rq);
+ BUG_ON(vd->next_rq && vd->prev_rq && blk_rq_pos(vd->next_rq) < blk_rq_pos(vd->prev_rq));
+
+ elv_rb_del(&vd->sort_list, rq);
+}
+
+/*
+ * add rq to rbtree and fifo
+ */
+static void
+vr_add_request(struct request_queue *q, struct request *rq)
+{
+ struct vr_data *vd = vr_get_data(q);
+ const int dir = rq_is_sync(rq);
+
+ vr_add_rq_rb(vd, rq);
+
+ if (vd->fifo_expire[dir]) {
+ rq_set_fifo_time(rq, jiffies + vd->fifo_expire[dir]);
+ list_add_tail(&rq->queuelist, &vd->fifo_list[dir]);
+ }
+}
+
+/*
+ * remove rq from rbtree and fifo.
+ */
+static void
+vr_remove_request(struct request_queue *q, struct request *rq)
+{
+ struct vr_data *vd = vr_get_data(q);
+
+ rq_fifo_clear(rq);
+ vr_del_rq_rb(vd, rq);
+}
+
+static int
+vr_merge(struct request_queue *q, struct request **rqp, struct bio *bio)
+{
+ sector_t sector = bio->bi_sector + bio_sectors(bio);
+ struct vr_data *vd = vr_get_data(q);
+ struct request *rq = elv_rb_find(&vd->sort_list, sector);
+
+ if (rq && elv_rq_merge_ok(rq, bio)) {
+ *rqp = rq;
+ return ELEVATOR_FRONT_MERGE;
+ }
+ return ELEVATOR_NO_MERGE;
+}
+
+static void
+vr_merged_request(struct request_queue *q, struct request *req, int type)
+{
+ struct vr_data *vd = vr_get_data(q);
+
+ /*
+ * if the merge was a front merge, we need to reposition request
+ */
+ if (type == ELEVATOR_FRONT_MERGE) {
+ vr_del_rq_rb(vd, req);
+ vr_add_rq_rb(vd, req);
+ }
+}
+
+static void
+vr_merged_requests(struct request_queue *q, struct request *rq,
+struct request *next)
+{
+ /*
+ * if next expires before rq, assign its expire time to rq
+ * and move into next position (next will be deleted) in fifo
+ */
+ if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist)) {
+ if (time_before(rq_fifo_time(next), rq_fifo_time(rq))) {
+ list_move(&rq->queuelist, &next->queuelist);
+ rq_set_fifo_time(rq, rq_fifo_time(next));
+ }
+ }
+
+ vr_remove_request(q, next);
+}
+
+/*
+ * move an entry to dispatch queue
+ */
+static void
+vr_move_request(struct vr_data *vd, struct request *rq)
+{
+ struct request_queue *q = rq->q;
+
+ if (blk_rq_pos(rq) > vd->last_sector)
+ vd->head_dir = FORWARD;
+ else
+ vd->head_dir = BACKWARD;
+
+ vd->last_sector = blk_rq_pos(rq);
+ vd->next_rq = elv_rb_latter_request(NULL, rq);
+ vd->prev_rq = elv_rb_former_request(NULL, rq);
+
+ BUG_ON(vd->next_rq && vd->next_rq == vd->prev_rq);
+
+ vr_remove_request(q, rq);
+ elv_dispatch_add_tail(q, rq);
+ vd->nbatched++;
+}
+
+/*
+ * get the first expired request in direction ddir
+ */
+static struct request *
+vr_expired_request(struct vr_data *vd, int ddir)
+{
+ struct request *rq;
+
+ if (list_empty(&vd->fifo_list[ddir]))
+ return NULL;
+
+ rq = rq_entry_fifo(vd->fifo_list[ddir].next);
+ if (time_after(jiffies, rq_fifo_time(rq)))
+ return rq;
+
+ return NULL;
+}
+
+/*
+ * Returns the oldest expired request
+ */
+static struct request *
+vr_check_fifo(struct vr_data *vd)
+{
+ struct request *rq_sync = vr_expired_request(vd, SYNC);
+ struct request *rq_async = vr_expired_request(vd, ASYNC);
+
+ if (rq_async && rq_sync) {
+ if (time_after(rq_fifo_time(rq_async), rq_fifo_time(rq_sync)))
+ return rq_sync;
+ }
+ else if (rq_sync)
+ return rq_sync;
+
+ return rq_async;
+}
+
+/*
+* Return the request with the lowest penalty
+*/
+static struct request *
+vr_choose_request(struct vr_data *vd)
+{
+ int penalty = (vd->rev_penalty) ? : INT_MAX;
+ struct request *next = vd->next_rq;
+ struct request *prev = vd->prev_rq;
+ sector_t next_pen, prev_pen;
+
+ BUG_ON(prev && prev == next);
+
+ if (!prev)
+ return next;
+ else if (!next)
+ return prev;
+
+/* At this point both prev and next are defined and distinct */
+
+ next_pen = blk_rq_pos(next) - vd->last_sector;
+ prev_pen = vd->last_sector - blk_rq_pos(prev);
+
+ if (vd->head_dir == FORWARD)
+ next_pen = do_div(next_pen, penalty);
+ else
+ prev_pen = do_div(prev_pen, penalty);
+
+ if (next_pen <= prev_pen)
+ return next;
+
+ return prev;
+}
+
+static int
+vr_dispatch_requests(struct request_queue *q, int force)
+{
+ struct vr_data *vd = vr_get_data(q);
+ struct request *rq = NULL;
+
+/* Check for and issue expired requests */
+ if (vd->nbatched > vd->fifo_batch) {
+ vd->nbatched = 0;
+ rq = vr_check_fifo(vd);
+ }
+
+ if (!rq) {
+ rq = vr_choose_request(vd);
+ if (!rq)
+ return 0;
+ }
+
+ vr_move_request(vd, rq);
+
+ return 1;
+}
+
+
+static void
+vr_exit_queue(struct elevator_queue *e)
+{
+ struct vr_data *vd = e->elevator_data;
+ BUG_ON(!RB_EMPTY_ROOT(&vd->sort_list));
+ kfree(vd);
+}
+
+/*
+* initialize elevator private data (vr_data).
+*/
+static void *vr_init_queue(struct request_queue *q)
+{
+ struct vr_data *vd;
+
+ vd = kmalloc_node(sizeof(*vd), GFP_KERNEL | __GFP_ZERO, q->node);
+ if (!vd)
+ return NULL;
+
+ INIT_LIST_HEAD(&vd->fifo_list[SYNC]);
+ INIT_LIST_HEAD(&vd->fifo_list[ASYNC]);
+ vd->sort_list = RB_ROOT;
+ vd->fifo_expire[SYNC] = sync_expire;
+ vd->fifo_expire[ASYNC] = async_expire;
+ vd->fifo_batch = fifo_batch;
+ vd->rev_penalty = rev_penalty;
+ return vd;
+}
+
+/*
+ * sysfs parts below
+ */
+
+static ssize_t
+vr_var_show(int var, char *page)
+{
+ return sprintf(page, "%d\n", var);
+}
+
+static ssize_t
+vr_var_store(int *var, const char *page, size_t count)
+{
+ *var = simple_strtol(page, NULL, 10);
+ return count;
+}
+
+#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
+static ssize_t __FUNC(struct elevator_queue *e, char *page) \
+{ \
+struct vr_data *vd = e->elevator_data; \
+int __data = __VAR; \
+if (__CONV) \
+__data = jiffies_to_msecs(__data); \
+return vr_var_show(__data, (page)); \
+}
+SHOW_FUNCTION(vr_sync_expire_show, vd->fifo_expire[SYNC], 1);
+SHOW_FUNCTION(vr_async_expire_show, vd->fifo_expire[ASYNC], 1);
+SHOW_FUNCTION(vr_fifo_batch_show, vd->fifo_batch, 0);
+SHOW_FUNCTION(vr_rev_penalty_show, vd->rev_penalty, 0);
+#undef SHOW_FUNCTION
+
+#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
+static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
+{ \
+struct vr_data *vd = e->elevator_data; \
+int __data; \
+int ret = vr_var_store(&__data, (page), count); \
+if (__data < (MIN)) \
+__data = (MIN); \
+else if (__data > (MAX)) \
+__data = (MAX); \
+if (__CONV) \
+*(__PTR) = msecs_to_jiffies(__data); \
+else \
+*(__PTR) = __data; \
+return ret; \
+}
+STORE_FUNCTION(vr_sync_expire_store, &vd->fifo_expire[SYNC], 0, INT_MAX, 1);
+STORE_FUNCTION(vr_async_expire_store, &vd->fifo_expire[ASYNC], 0, INT_MAX, 1);
+STORE_FUNCTION(vr_fifo_batch_store, &vd->fifo_batch, 0, INT_MAX, 0);
+STORE_FUNCTION(vr_rev_penalty_store, &vd->rev_penalty, 0, INT_MAX, 0);
+#undef STORE_FUNCTION
+
+#define DD_ATTR(name) \
+__ATTR(name, S_IRUGO|S_IWUSR, vr_##name##_show, \
+vr_##name##_store)
+
+static struct elv_fs_entry vr_attrs[] = {
+ DD_ATTR(sync_expire),
+ DD_ATTR(async_expire),
+ DD_ATTR(fifo_batch),
+ DD_ATTR(rev_penalty),
+ __ATTR_NULL
+};
+
+static struct elevator_type iosched_vr = {
+ .ops = {
+ .elevator_merge_fn = vr_merge,
+ .elevator_merged_fn = vr_merged_request,
+ .elevator_merge_req_fn = vr_merged_requests,
+ .elevator_dispatch_fn = vr_dispatch_requests,
+ .elevator_add_req_fn = vr_add_request,
+ .elevator_former_req_fn = elv_rb_former_request,
+ .elevator_latter_req_fn = elv_rb_latter_request,
+ .elevator_init_fn = vr_init_queue,
+ .elevator_exit_fn = vr_exit_queue,
+ },
+
+ .elevator_attrs = vr_attrs,
+ .elevator_name = "vr",
+ .elevator_owner = THIS_MODULE,
+};
+
+static int __init vr_init(void)
+{
+ elv_register(&iosched_vr);
+
+ return 0;
+}
+
+static void __exit vr_exit(void)
+{
+ elv_unregister(&iosched_vr);
+}
+
+module_init(vr_init);
+module_exit(vr_exit);
+
+MODULE_AUTHOR("Aaron Carroll");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("V(R) IO scheduler");
diff --git a/block/zen-iosched.c b/block/zen-iosched.c
new file mode 100644
index 0000000..77145de
--- /dev/null
+++ b/block/zen-iosched.c
@@ -0,0 +1,277 @@
+/*
+ * Zen IO scheduler
+ * Primarily based on Noop, deadline, and SIO IO schedulers.
+ *
+ * Copyright (C) 2012 Brandon Berhent <bbedward@gmail.com>
+ *
+ * FCFS, dispatches are back-inserted, deadlines ensure fairness.
+ * Should work best with devices where there is no travel delay.
+ */
+#include <linux/blkdev.h>
+#include <linux/elevator.h>
+#include <linux/bio.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+
+enum zen_data_dir { ASYNC, SYNC };
+
+static const int sync_expire = HZ / 4; /* max time before a sync is submitted. */
+static const int async_expire = 2 * HZ; /* ditto for async, these limits are SOFT! */
+static const int fifo_batch = 1;
+
+struct zen_data {
+ /* Runtime Data */
+ /* Requests are only present on fifo_list */
+ struct list_head fifo_list[2];
+
+ unsigned int batching; /* number of sequential requests made */
+
+ /* tunables */
+ int fifo_expire[2];
+ int fifo_batch;
+};
+
+static inline struct zen_data *
+zen_get_data(struct request_queue *q) {
+ return q->elevator->elevator_data;
+}
+
+static void zen_dispatch(struct zen_data *, struct request *);
+
+static void
+zen_merged_requests(struct request_queue *q, struct request *rq,
+ struct request *next)
+{
+ /*
+ * if next expires before rq, assign its expire time to arq
+ * and move into next position (next will be deleted) in fifo
+ */
+ if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist)) {
+ if (time_before(rq_fifo_time(next), rq_fifo_time(rq))) {
+ list_move(&rq->queuelist, &next->queuelist);
+ rq_set_fifo_time(rq, rq_fifo_time(next));
+ }
+ }
+
+ /* next request is gone */
+ rq_fifo_clear(next);
+}
+
+static void zen_add_request(struct request_queue *q, struct request *rq)
+{
+ struct zen_data *zdata = zen_get_data(q);
+ const int dir = rq_data_dir(rq);
+
+ if (zdata->fifo_expire[dir]) {
+ rq_set_fifo_time(rq, jiffies + zdata->fifo_expire[dir]);
+ list_add_tail(&rq->queuelist, &zdata->fifo_list[dir]);
+ }
+}
+
+static void zen_dispatch(struct zen_data *zdata, struct request *rq)
+{
+ /* Remove request from list and dispatch it */
+ rq_fifo_clear(rq);
+ elv_dispatch_add_tail(rq->q, rq);
+
+ /* Increment # of sequential requests */
+ zdata->batching++;
+}
+
+/*
+ * get the first expired request in direction ddir
+ */
+static struct request *
+zen_expired_request(struct zen_data *zdata, int ddir)
+{
+ struct request *rq;
+
+ if (list_empty(&zdata->fifo_list[ddir]))
+ return NULL;
+
+ rq = rq_entry_fifo(zdata->fifo_list[ddir].next);
+ if (time_after(jiffies, rq_fifo_time(rq)))
+ return rq;
+
+ return NULL;
+}
+
+/*
+ * zen_check_fifo returns 0 if there are no expired requests on the fifo,
+ * otherwise it returns the next expired request
+ */
+static struct request *
+zen_check_fifo(struct zen_data *zdata)
+{
+ struct request *rq_sync = zen_expired_request(zdata, SYNC);
+ struct request *rq_async = zen_expired_request(zdata, ASYNC);
+
+ if (rq_async && rq_sync) {
+ if (time_after(rq_fifo_time(rq_async), rq_fifo_time(rq_sync)))
+ return rq_sync;
+ } else if (rq_sync) {
+ return rq_sync;
+ } else if (rq_async) {
+ return rq_async;
+ }
+
+ return 0;
+}
+
+static struct request *
+zen_choose_request(struct zen_data *zdata)
+{
+ /*
+ * Retrieve request from available fifo list.
+ * Synchronous requests have priority over asynchronous.
+ */
+ if (!list_empty(&zdata->fifo_list[SYNC]))
+ return rq_entry_fifo(zdata->fifo_list[SYNC].next);
+ if (!list_empty(&zdata->fifo_list[ASYNC]))
+ return rq_entry_fifo(zdata->fifo_list[ASYNC].next);
+
+ return NULL;
+}
+
+static int zen_dispatch_requests(struct request_queue *q, int force)
+{
+ struct zen_data *zdata = zen_get_data(q);
+ struct request *rq = NULL;
+
+ /* Check for and issue expired requests */
+ if (zdata->batching > zdata->fifo_batch) {
+ zdata->batching = 0;
+ rq = zen_check_fifo(zdata);
+ }
+
+ if (!rq) {
+ rq = zen_choose_request(zdata);
+ if (!rq)
+ return 0;
+ }
+
+ zen_dispatch(zdata, rq);
+
+ return 1;
+}
+
+static void *zen_init_queue(struct request_queue *q)
+{
+ struct zen_data *zdata;
+
+ zdata = kmalloc_node(sizeof(*zdata), GFP_KERNEL, q->node);
+ if (!zdata)
+ return NULL;
+ INIT_LIST_HEAD(&zdata->fifo_list[SYNC]);
+ INIT_LIST_HEAD(&zdata->fifo_list[ASYNC]);
+ zdata->fifo_expire[SYNC] = sync_expire;
+ zdata->fifo_expire[ASYNC] = async_expire;
+ zdata->fifo_batch = fifo_batch;
+ return zdata;
+}
+
+static void zen_exit_queue(struct elevator_queue *e)
+{
+ struct zen_data *zdata = e->elevator_data;
+
+ BUG_ON(!list_empty(&zdata->fifo_list[SYNC]));
+ BUG_ON(!list_empty(&zdata->fifo_list[ASYNC]));
+ kfree(zdata);
+}
+
+/* Sysfs */
+static ssize_t
+zen_var_show(int var, char *page)
+{
+ return sprintf(page, "%d\n", var);
+}
+
+static ssize_t
+zen_var_store(int *var, const char *page, size_t count)
+{
+ *var = simple_strtol(page, NULL, 10);
+ return count;
+}
+
+#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
+static ssize_t __FUNC(struct elevator_queue *e, char *page) \
+{ \
+ struct zen_data *zdata = e->elevator_data; \
+ int __data = __VAR; \
+ if (__CONV) \
+ __data = jiffies_to_msecs(__data); \
+ return zen_var_show(__data, (page)); \
+}
+SHOW_FUNCTION(zen_sync_expire_show, zdata->fifo_expire[SYNC], 1);
+SHOW_FUNCTION(zen_async_expire_show, zdata->fifo_expire[ASYNC], 1);
+SHOW_FUNCTION(zen_fifo_batch_show, zdata->fifo_batch, 0);
+#undef SHOW_FUNCTION
+
+#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
+static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
+{ \
+ struct zen_data *zdata = e->elevator_data; \
+ int __data; \
+ int ret = zen_var_store(&__data, (page), count); \
+ if (__data < (MIN)) \
+ __data = (MIN); \
+ else if (__data > (MAX)) \
+ __data = (MAX); \
+ if (__CONV) \
+ *(__PTR) = msecs_to_jiffies(__data); \
+ else \
+ *(__PTR) = __data; \
+ return ret; \
+}
+STORE_FUNCTION(zen_sync_expire_store, &zdata->fifo_expire[SYNC], 0, INT_MAX, 1);
+STORE_FUNCTION(zen_async_expire_store, &zdata->fifo_expire[ASYNC], 0, INT_MAX, 1);
+STORE_FUNCTION(zen_fifo_batch_store, &zdata->fifo_batch, 0, INT_MAX, 0);
+#undef STORE_FUNCTION
+
+#define DD_ATTR(name) \
+ __ATTR(name, S_IRUGO|S_IWUSR, zen_##name##_show, \
+ zen_##name##_store)
+
+static struct elv_fs_entry zen_attrs[] = {
+ DD_ATTR(sync_expire),
+ DD_ATTR(async_expire),
+ DD_ATTR(fifo_batch),
+ __ATTR_NULL
+};
+
+static struct elevator_type iosched_zen = {
+ .ops = {
+ .elevator_merge_req_fn = zen_merged_requests,
+ .elevator_dispatch_fn = zen_dispatch_requests,
+ .elevator_add_req_fn = zen_add_request,
+ .elevator_former_req_fn = elv_rb_former_request,
+ .elevator_latter_req_fn = elv_rb_latter_request,
+ .elevator_init_fn = zen_init_queue,
+ .elevator_exit_fn = zen_exit_queue,
+ },
+ .elevator_attrs = zen_attrs,
+ .elevator_name = "zen",
+ .elevator_owner = THIS_MODULE,
+};
+
+static int __init zen_init(void)
+{
+ elv_register(&iosched_zen);
+
+ return 0;
+}
+
+static void __exit zen_exit(void)
+{
+ elv_unregister(&iosched_zen);
+}
+
+module_init(zen_init);
+module_exit(zen_exit);
+
+
+MODULE_AUTHOR("Brandon Berhent");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Zen IO scheduler");
+MODULE_VERSION("1.0");
diff --git a/drivers/md/dm-builtin.c b/drivers/md/dm-builtin.c
new file mode 100644
index 0000000..797daec
--- /dev/null
+++ b/drivers/md/dm-builtin.c
@@ -0,0 +1,50 @@
+#include "dm.h"
+
+#include <linux/export.h>
+
+/*
+ * The kobject release method must not be placed in the module itself,
+ * otherwise we are subject to module unload races.
+ *
+ * The release method is called when the last reference to the kobject is
+ * dropped. It may be called by any other kernel code that drops the last
+ * reference.
+ *
+ * The release method suffers from module unload race. We may prevent the
+ * module from being unloaded at the start of the release method (using
+ * increased module reference count or synchronizing against the release
+ * method), however there is no way to prevent the module from being
+ * unloaded at the end of the release method.
+ *
+ * If this code were placed in the dm module, the following race may
+ * happen:
+ * 1. Some other process takes a reference to dm kobject
+ * 2. The user issues ioctl function to unload the dm device
+ * 3. dm_sysfs_exit calls kobject_put, however the object is not released
+ * because of the other reference taken at step 1
+ * 4. dm_sysfs_exit waits on the completion
+ * 5. The other process that took the reference in step 1 drops it,
+ * dm_kobject_release is called from this process
+ * 6. dm_kobject_release calls complete()
+ * 7. a reschedule happens before dm_kobject_release returns
+ * 8. dm_sysfs_exit continues, the dm device is unloaded, module reference
+ * count is decremented
+ * 9. The user unloads the dm module
+ * 10. The other process that was rescheduled in step 7 continues to run,
+ * it is now executing code in unloaded module, so it crashes
+ *
+ * Note that if the process that takes the foreign reference to dm kobject
+ * has a low priority and the system is sufficiently loaded with
+ * higher-priority processes that prevent the low-priority process from
+ * being scheduled long enough, this bug may really happen.
+ *
+ * In order to fix this module unload race, we place the release method
+ * into a helper code that is compiled directly into the kernel.
+ */
+
+void dm_kobject_release(struct kobject *kobj)
+{
+ complete(dm_get_completion_from_kobject(kobj));
+}
+
+EXPORT_SYMBOL(dm_kobject_release);
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