linux/block/blk-mq.c
Jens Axboe 200e86b337 blk-mq: only apply active queue tag throttling for driver tags
If we have a scheduler attached, we have two sets of tags. We don't
want to apply our active queue throttling for the scheduler side
of tags, that only applies to driver tags since that's the resource
we need to dispatch an IO.

Signed-off-by: Jens Axboe <axboe@fb.com>
2017-01-25 08:11:38 -07:00

2811 lines
67 KiB
C

/*
* Block multiqueue core code
*
* Copyright (C) 2013-2014 Jens Axboe
* Copyright (C) 2013-2014 Christoph Hellwig
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/backing-dev.h>
#include <linux/bio.h>
#include <linux/blkdev.h>
#include <linux/kmemleak.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/workqueue.h>
#include <linux/smp.h>
#include <linux/llist.h>
#include <linux/list_sort.h>
#include <linux/cpu.h>
#include <linux/cache.h>
#include <linux/sched/sysctl.h>
#include <linux/delay.h>
#include <linux/crash_dump.h>
#include <linux/prefetch.h>
#include <trace/events/block.h>
#include <linux/blk-mq.h>
#include "blk.h"
#include "blk-mq.h"
#include "blk-mq-tag.h"
#include "blk-stat.h"
#include "blk-wbt.h"
#include "blk-mq-sched.h"
static DEFINE_MUTEX(all_q_mutex);
static LIST_HEAD(all_q_list);
/*
* Check if any of the ctx's have pending work in this hardware queue
*/
static bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx *hctx)
{
return sbitmap_any_bit_set(&hctx->ctx_map) ||
!list_empty_careful(&hctx->dispatch) ||
blk_mq_sched_has_work(hctx);
}
/*
* Mark this ctx as having pending work in this hardware queue
*/
static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx *hctx,
struct blk_mq_ctx *ctx)
{
if (!sbitmap_test_bit(&hctx->ctx_map, ctx->index_hw))
sbitmap_set_bit(&hctx->ctx_map, ctx->index_hw);
}
static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx *hctx,
struct blk_mq_ctx *ctx)
{
sbitmap_clear_bit(&hctx->ctx_map, ctx->index_hw);
}
void blk_mq_freeze_queue_start(struct request_queue *q)
{
int freeze_depth;
freeze_depth = atomic_inc_return(&q->mq_freeze_depth);
if (freeze_depth == 1) {
percpu_ref_kill(&q->q_usage_counter);
blk_mq_run_hw_queues(q, false);
}
}
EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_start);
static void blk_mq_freeze_queue_wait(struct request_queue *q)
{
wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->q_usage_counter));
}
/*
* Guarantee no request is in use, so we can change any data structure of
* the queue afterward.
*/
void blk_freeze_queue(struct request_queue *q)
{
/*
* In the !blk_mq case we are only calling this to kill the
* q_usage_counter, otherwise this increases the freeze depth
* and waits for it to return to zero. For this reason there is
* no blk_unfreeze_queue(), and blk_freeze_queue() is not
* exported to drivers as the only user for unfreeze is blk_mq.
*/
blk_mq_freeze_queue_start(q);
blk_mq_freeze_queue_wait(q);
}
void blk_mq_freeze_queue(struct request_queue *q)
{
/*
* ...just an alias to keep freeze and unfreeze actions balanced
* in the blk_mq_* namespace
*/
blk_freeze_queue(q);
}
EXPORT_SYMBOL_GPL(blk_mq_freeze_queue);
void blk_mq_unfreeze_queue(struct request_queue *q)
{
int freeze_depth;
freeze_depth = atomic_dec_return(&q->mq_freeze_depth);
WARN_ON_ONCE(freeze_depth < 0);
if (!freeze_depth) {
percpu_ref_reinit(&q->q_usage_counter);
wake_up_all(&q->mq_freeze_wq);
}
}
EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue);
/**
* blk_mq_quiesce_queue() - wait until all ongoing queue_rq calls have finished
* @q: request queue.
*
* Note: this function does not prevent that the struct request end_io()
* callback function is invoked. Additionally, it is not prevented that
* new queue_rq() calls occur unless the queue has been stopped first.
*/
void blk_mq_quiesce_queue(struct request_queue *q)
{
struct blk_mq_hw_ctx *hctx;
unsigned int i;
bool rcu = false;
blk_mq_stop_hw_queues(q);
queue_for_each_hw_ctx(q, hctx, i) {
if (hctx->flags & BLK_MQ_F_BLOCKING)
synchronize_srcu(&hctx->queue_rq_srcu);
else
rcu = true;
}
if (rcu)
synchronize_rcu();
}
EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue);
void blk_mq_wake_waiters(struct request_queue *q)
{
struct blk_mq_hw_ctx *hctx;
unsigned int i;
queue_for_each_hw_ctx(q, hctx, i)
if (blk_mq_hw_queue_mapped(hctx))
blk_mq_tag_wakeup_all(hctx->tags, true);
/*
* If we are called because the queue has now been marked as
* dying, we need to ensure that processes currently waiting on
* the queue are notified as well.
*/
wake_up_all(&q->mq_freeze_wq);
}
bool blk_mq_can_queue(struct blk_mq_hw_ctx *hctx)
{
return blk_mq_has_free_tags(hctx->tags);
}
EXPORT_SYMBOL(blk_mq_can_queue);
void blk_mq_rq_ctx_init(struct request_queue *q, struct blk_mq_ctx *ctx,
struct request *rq, unsigned int op)
{
INIT_LIST_HEAD(&rq->queuelist);
/* csd/requeue_work/fifo_time is initialized before use */
rq->q = q;
rq->mq_ctx = ctx;
rq->cmd_flags = op;
if (blk_queue_io_stat(q))
rq->rq_flags |= RQF_IO_STAT;
/* do not touch atomic flags, it needs atomic ops against the timer */
rq->cpu = -1;
INIT_HLIST_NODE(&rq->hash);
RB_CLEAR_NODE(&rq->rb_node);
rq->rq_disk = NULL;
rq->part = NULL;
rq->start_time = jiffies;
#ifdef CONFIG_BLK_CGROUP
rq->rl = NULL;
set_start_time_ns(rq);
rq->io_start_time_ns = 0;
#endif
rq->nr_phys_segments = 0;
#if defined(CONFIG_BLK_DEV_INTEGRITY)
rq->nr_integrity_segments = 0;
#endif
rq->special = NULL;
/* tag was already set */
rq->errors = 0;
rq->cmd = rq->__cmd;
rq->extra_len = 0;
rq->sense_len = 0;
rq->resid_len = 0;
rq->sense = NULL;
INIT_LIST_HEAD(&rq->timeout_list);
rq->timeout = 0;
rq->end_io = NULL;
rq->end_io_data = NULL;
rq->next_rq = NULL;
ctx->rq_dispatched[op_is_sync(op)]++;
}
EXPORT_SYMBOL_GPL(blk_mq_rq_ctx_init);
struct request *__blk_mq_alloc_request(struct blk_mq_alloc_data *data,
unsigned int op)
{
struct request *rq;
unsigned int tag;
tag = blk_mq_get_tag(data);
if (tag != BLK_MQ_TAG_FAIL) {
struct blk_mq_tags *tags = blk_mq_tags_from_data(data);
rq = tags->static_rqs[tag];
if (data->flags & BLK_MQ_REQ_INTERNAL) {
rq->tag = -1;
rq->internal_tag = tag;
} else {
if (blk_mq_tag_busy(data->hctx)) {
rq->rq_flags = RQF_MQ_INFLIGHT;
atomic_inc(&data->hctx->nr_active);
}
rq->tag = tag;
rq->internal_tag = -1;
}
blk_mq_rq_ctx_init(data->q, data->ctx, rq, op);
return rq;
}
return NULL;
}
EXPORT_SYMBOL_GPL(__blk_mq_alloc_request);
struct request *blk_mq_alloc_request(struct request_queue *q, int rw,
unsigned int flags)
{
struct blk_mq_alloc_data alloc_data;
struct request *rq;
int ret;
ret = blk_queue_enter(q, flags & BLK_MQ_REQ_NOWAIT);
if (ret)
return ERR_PTR(ret);
rq = blk_mq_sched_get_request(q, NULL, rw, &alloc_data);
blk_mq_put_ctx(alloc_data.ctx);
blk_queue_exit(q);
if (!rq)
return ERR_PTR(-EWOULDBLOCK);
rq->__data_len = 0;
rq->__sector = (sector_t) -1;
rq->bio = rq->biotail = NULL;
return rq;
}
EXPORT_SYMBOL(blk_mq_alloc_request);
struct request *blk_mq_alloc_request_hctx(struct request_queue *q, int rw,
unsigned int flags, unsigned int hctx_idx)
{
struct blk_mq_hw_ctx *hctx;
struct blk_mq_ctx *ctx;
struct request *rq;
struct blk_mq_alloc_data alloc_data;
int ret;
/*
* If the tag allocator sleeps we could get an allocation for a
* different hardware context. No need to complicate the low level
* allocator for this for the rare use case of a command tied to
* a specific queue.
*/
if (WARN_ON_ONCE(!(flags & BLK_MQ_REQ_NOWAIT)))
return ERR_PTR(-EINVAL);
if (hctx_idx >= q->nr_hw_queues)
return ERR_PTR(-EIO);
ret = blk_queue_enter(q, true);
if (ret)
return ERR_PTR(ret);
/*
* Check if the hardware context is actually mapped to anything.
* If not tell the caller that it should skip this queue.
*/
hctx = q->queue_hw_ctx[hctx_idx];
if (!blk_mq_hw_queue_mapped(hctx)) {
ret = -EXDEV;
goto out_queue_exit;
}
ctx = __blk_mq_get_ctx(q, cpumask_first(hctx->cpumask));
blk_mq_set_alloc_data(&alloc_data, q, flags, ctx, hctx);
rq = __blk_mq_alloc_request(&alloc_data, rw);
if (!rq) {
ret = -EWOULDBLOCK;
goto out_queue_exit;
}
return rq;
out_queue_exit:
blk_queue_exit(q);
return ERR_PTR(ret);
}
EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx);
void __blk_mq_finish_request(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
struct request *rq)
{
const int sched_tag = rq->internal_tag;
struct request_queue *q = rq->q;
if (rq->rq_flags & RQF_MQ_INFLIGHT)
atomic_dec(&hctx->nr_active);
wbt_done(q->rq_wb, &rq->issue_stat);
rq->rq_flags = 0;
clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
clear_bit(REQ_ATOM_POLL_SLEPT, &rq->atomic_flags);
if (rq->tag != -1)
blk_mq_put_tag(hctx, hctx->tags, ctx, rq->tag);
if (sched_tag != -1)
blk_mq_sched_completed_request(hctx, rq);
blk_queue_exit(q);
}
static void blk_mq_finish_hctx_request(struct blk_mq_hw_ctx *hctx,
struct request *rq)
{
struct blk_mq_ctx *ctx = rq->mq_ctx;
ctx->rq_completed[rq_is_sync(rq)]++;
__blk_mq_finish_request(hctx, ctx, rq);
}
void blk_mq_finish_request(struct request *rq)
{
blk_mq_finish_hctx_request(blk_mq_map_queue(rq->q, rq->mq_ctx->cpu), rq);
}
void blk_mq_free_request(struct request *rq)
{
blk_mq_sched_put_request(rq);
}
EXPORT_SYMBOL_GPL(blk_mq_free_request);
inline void __blk_mq_end_request(struct request *rq, int error)
{
blk_account_io_done(rq);
if (rq->end_io) {
wbt_done(rq->q->rq_wb, &rq->issue_stat);
rq->end_io(rq, error);
} else {
if (unlikely(blk_bidi_rq(rq)))
blk_mq_free_request(rq->next_rq);
blk_mq_free_request(rq);
}
}
EXPORT_SYMBOL(__blk_mq_end_request);
void blk_mq_end_request(struct request *rq, int error)
{
if (blk_update_request(rq, error, blk_rq_bytes(rq)))
BUG();
__blk_mq_end_request(rq, error);
}
EXPORT_SYMBOL(blk_mq_end_request);
static void __blk_mq_complete_request_remote(void *data)
{
struct request *rq = data;
rq->q->softirq_done_fn(rq);
}
static void blk_mq_ipi_complete_request(struct request *rq)
{
struct blk_mq_ctx *ctx = rq->mq_ctx;
bool shared = false;
int cpu;
if (!test_bit(QUEUE_FLAG_SAME_COMP, &rq->q->queue_flags)) {
rq->q->softirq_done_fn(rq);
return;
}
cpu = get_cpu();
if (!test_bit(QUEUE_FLAG_SAME_FORCE, &rq->q->queue_flags))
shared = cpus_share_cache(cpu, ctx->cpu);
if (cpu != ctx->cpu && !shared && cpu_online(ctx->cpu)) {
rq->csd.func = __blk_mq_complete_request_remote;
rq->csd.info = rq;
rq->csd.flags = 0;
smp_call_function_single_async(ctx->cpu, &rq->csd);
} else {
rq->q->softirq_done_fn(rq);
}
put_cpu();
}
static void blk_mq_stat_add(struct request *rq)
{
if (rq->rq_flags & RQF_STATS) {
/*
* We could rq->mq_ctx here, but there's less of a risk
* of races if we have the completion event add the stats
* to the local software queue.
*/
struct blk_mq_ctx *ctx;
ctx = __blk_mq_get_ctx(rq->q, raw_smp_processor_id());
blk_stat_add(&ctx->stat[rq_data_dir(rq)], rq);
}
}
static void __blk_mq_complete_request(struct request *rq)
{
struct request_queue *q = rq->q;
blk_mq_stat_add(rq);
if (!q->softirq_done_fn)
blk_mq_end_request(rq, rq->errors);
else
blk_mq_ipi_complete_request(rq);
}
/**
* blk_mq_complete_request - end I/O on a request
* @rq: the request being processed
*
* Description:
* Ends all I/O on a request. It does not handle partial completions.
* The actual completion happens out-of-order, through a IPI handler.
**/
void blk_mq_complete_request(struct request *rq, int error)
{
struct request_queue *q = rq->q;
if (unlikely(blk_should_fake_timeout(q)))
return;
if (!blk_mark_rq_complete(rq)) {
rq->errors = error;
__blk_mq_complete_request(rq);
}
}
EXPORT_SYMBOL(blk_mq_complete_request);
int blk_mq_request_started(struct request *rq)
{
return test_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
}
EXPORT_SYMBOL_GPL(blk_mq_request_started);
void blk_mq_start_request(struct request *rq)
{
struct request_queue *q = rq->q;
blk_mq_sched_started_request(rq);
trace_block_rq_issue(q, rq);
rq->resid_len = blk_rq_bytes(rq);
if (unlikely(blk_bidi_rq(rq)))
rq->next_rq->resid_len = blk_rq_bytes(rq->next_rq);
if (test_bit(QUEUE_FLAG_STATS, &q->queue_flags)) {
blk_stat_set_issue_time(&rq->issue_stat);
rq->rq_flags |= RQF_STATS;
wbt_issue(q->rq_wb, &rq->issue_stat);
}
blk_add_timer(rq);
/*
* Ensure that ->deadline is visible before set the started
* flag and clear the completed flag.
*/
smp_mb__before_atomic();
/*
* Mark us as started and clear complete. Complete might have been
* set if requeue raced with timeout, which then marked it as
* complete. So be sure to clear complete again when we start
* the request, otherwise we'll ignore the completion event.
*/
if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
set_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
if (test_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags))
clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
if (q->dma_drain_size && blk_rq_bytes(rq)) {
/*
* Make sure space for the drain appears. We know we can do
* this because max_hw_segments has been adjusted to be one
* fewer than the device can handle.
*/
rq->nr_phys_segments++;
}
}
EXPORT_SYMBOL(blk_mq_start_request);
static void __blk_mq_requeue_request(struct request *rq)
{
struct request_queue *q = rq->q;
trace_block_rq_requeue(q, rq);
wbt_requeue(q->rq_wb, &rq->issue_stat);
blk_mq_sched_requeue_request(rq);
if (test_and_clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags)) {
if (q->dma_drain_size && blk_rq_bytes(rq))
rq->nr_phys_segments--;
}
}
void blk_mq_requeue_request(struct request *rq, bool kick_requeue_list)
{
__blk_mq_requeue_request(rq);
BUG_ON(blk_queued_rq(rq));
blk_mq_add_to_requeue_list(rq, true, kick_requeue_list);
}
EXPORT_SYMBOL(blk_mq_requeue_request);
static void blk_mq_requeue_work(struct work_struct *work)
{
struct request_queue *q =
container_of(work, struct request_queue, requeue_work.work);
LIST_HEAD(rq_list);
struct request *rq, *next;
unsigned long flags;
spin_lock_irqsave(&q->requeue_lock, flags);
list_splice_init(&q->requeue_list, &rq_list);
spin_unlock_irqrestore(&q->requeue_lock, flags);
list_for_each_entry_safe(rq, next, &rq_list, queuelist) {
if (!(rq->rq_flags & RQF_SOFTBARRIER))
continue;
rq->rq_flags &= ~RQF_SOFTBARRIER;
list_del_init(&rq->queuelist);
blk_mq_sched_insert_request(rq, true, false, false);
}
while (!list_empty(&rq_list)) {
rq = list_entry(rq_list.next, struct request, queuelist);
list_del_init(&rq->queuelist);
blk_mq_sched_insert_request(rq, false, false, false);
}
blk_mq_run_hw_queues(q, false);
}
void blk_mq_add_to_requeue_list(struct request *rq, bool at_head,
bool kick_requeue_list)
{
struct request_queue *q = rq->q;
unsigned long flags;
/*
* We abuse this flag that is otherwise used by the I/O scheduler to
* request head insertation from the workqueue.
*/
BUG_ON(rq->rq_flags & RQF_SOFTBARRIER);
spin_lock_irqsave(&q->requeue_lock, flags);
if (at_head) {
rq->rq_flags |= RQF_SOFTBARRIER;
list_add(&rq->queuelist, &q->requeue_list);
} else {
list_add_tail(&rq->queuelist, &q->requeue_list);
}
spin_unlock_irqrestore(&q->requeue_lock, flags);
if (kick_requeue_list)
blk_mq_kick_requeue_list(q);
}
EXPORT_SYMBOL(blk_mq_add_to_requeue_list);
void blk_mq_kick_requeue_list(struct request_queue *q)
{
kblockd_schedule_delayed_work(&q->requeue_work, 0);
}
EXPORT_SYMBOL(blk_mq_kick_requeue_list);
void blk_mq_delay_kick_requeue_list(struct request_queue *q,
unsigned long msecs)
{
kblockd_schedule_delayed_work(&q->requeue_work,
msecs_to_jiffies(msecs));
}
EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list);
void blk_mq_abort_requeue_list(struct request_queue *q)
{
unsigned long flags;
LIST_HEAD(rq_list);
spin_lock_irqsave(&q->requeue_lock, flags);
list_splice_init(&q->requeue_list, &rq_list);
spin_unlock_irqrestore(&q->requeue_lock, flags);
while (!list_empty(&rq_list)) {
struct request *rq;
rq = list_first_entry(&rq_list, struct request, queuelist);
list_del_init(&rq->queuelist);
rq->errors = -EIO;
blk_mq_end_request(rq, rq->errors);
}
}
EXPORT_SYMBOL(blk_mq_abort_requeue_list);
struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag)
{
if (tag < tags->nr_tags) {
prefetch(tags->rqs[tag]);
return tags->rqs[tag];
}
return NULL;
}
EXPORT_SYMBOL(blk_mq_tag_to_rq);
struct blk_mq_timeout_data {
unsigned long next;
unsigned int next_set;
};
void blk_mq_rq_timed_out(struct request *req, bool reserved)
{
const struct blk_mq_ops *ops = req->q->mq_ops;
enum blk_eh_timer_return ret = BLK_EH_RESET_TIMER;
/*
* We know that complete is set at this point. If STARTED isn't set
* anymore, then the request isn't active and the "timeout" should
* just be ignored. This can happen due to the bitflag ordering.
* Timeout first checks if STARTED is set, and if it is, assumes
* the request is active. But if we race with completion, then
* we both flags will get cleared. So check here again, and ignore
* a timeout event with a request that isn't active.
*/
if (!test_bit(REQ_ATOM_STARTED, &req->atomic_flags))
return;
if (ops->timeout)
ret = ops->timeout(req, reserved);
switch (ret) {
case BLK_EH_HANDLED:
__blk_mq_complete_request(req);
break;
case BLK_EH_RESET_TIMER:
blk_add_timer(req);
blk_clear_rq_complete(req);
break;
case BLK_EH_NOT_HANDLED:
break;
default:
printk(KERN_ERR "block: bad eh return: %d\n", ret);
break;
}
}
static void blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
struct request *rq, void *priv, bool reserved)
{
struct blk_mq_timeout_data *data = priv;
if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags)) {
/*
* If a request wasn't started before the queue was
* marked dying, kill it here or it'll go unnoticed.
*/
if (unlikely(blk_queue_dying(rq->q))) {
rq->errors = -EIO;
blk_mq_end_request(rq, rq->errors);
}
return;
}
if (time_after_eq(jiffies, rq->deadline)) {
if (!blk_mark_rq_complete(rq))
blk_mq_rq_timed_out(rq, reserved);
} else if (!data->next_set || time_after(data->next, rq->deadline)) {
data->next = rq->deadline;
data->next_set = 1;
}
}
static void blk_mq_timeout_work(struct work_struct *work)
{
struct request_queue *q =
container_of(work, struct request_queue, timeout_work);
struct blk_mq_timeout_data data = {
.next = 0,
.next_set = 0,
};
int i;
/* A deadlock might occur if a request is stuck requiring a
* timeout at the same time a queue freeze is waiting
* completion, since the timeout code would not be able to
* acquire the queue reference here.
*
* That's why we don't use blk_queue_enter here; instead, we use
* percpu_ref_tryget directly, because we need to be able to
* obtain a reference even in the short window between the queue
* starting to freeze, by dropping the first reference in
* blk_mq_freeze_queue_start, and the moment the last request is
* consumed, marked by the instant q_usage_counter reaches
* zero.
*/
if (!percpu_ref_tryget(&q->q_usage_counter))
return;
blk_mq_queue_tag_busy_iter(q, blk_mq_check_expired, &data);
if (data.next_set) {
data.next = blk_rq_timeout(round_jiffies_up(data.next));
mod_timer(&q->timeout, data.next);
} else {
struct blk_mq_hw_ctx *hctx;
queue_for_each_hw_ctx(q, hctx, i) {
/* the hctx may be unmapped, so check it here */
if (blk_mq_hw_queue_mapped(hctx))
blk_mq_tag_idle(hctx);
}
}
blk_queue_exit(q);
}
/*
* Reverse check our software queue for entries that we could potentially
* merge with. Currently includes a hand-wavy stop count of 8, to not spend
* too much time checking for merges.
*/
static bool blk_mq_attempt_merge(struct request_queue *q,
struct blk_mq_ctx *ctx, struct bio *bio)
{
struct request *rq;
int checked = 8;
list_for_each_entry_reverse(rq, &ctx->rq_list, queuelist) {
int el_ret;
if (!checked--)
break;
if (!blk_rq_merge_ok(rq, bio))
continue;
el_ret = blk_try_merge(rq, bio);
if (el_ret == ELEVATOR_NO_MERGE)
continue;
if (!blk_mq_sched_allow_merge(q, rq, bio))
break;
if (el_ret == ELEVATOR_BACK_MERGE) {
if (bio_attempt_back_merge(q, rq, bio)) {
ctx->rq_merged++;
return true;
}
break;
} else if (el_ret == ELEVATOR_FRONT_MERGE) {
if (bio_attempt_front_merge(q, rq, bio)) {
ctx->rq_merged++;
return true;
}
break;
}
}
return false;
}
struct flush_busy_ctx_data {
struct blk_mq_hw_ctx *hctx;
struct list_head *list;
};
static bool flush_busy_ctx(struct sbitmap *sb, unsigned int bitnr, void *data)
{
struct flush_busy_ctx_data *flush_data = data;
struct blk_mq_hw_ctx *hctx = flush_data->hctx;
struct blk_mq_ctx *ctx = hctx->ctxs[bitnr];
sbitmap_clear_bit(sb, bitnr);
spin_lock(&ctx->lock);
list_splice_tail_init(&ctx->rq_list, flush_data->list);
spin_unlock(&ctx->lock);
return true;
}
/*
* Process software queues that have been marked busy, splicing them
* to the for-dispatch
*/
void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list)
{
struct flush_busy_ctx_data data = {
.hctx = hctx,
.list = list,
};
sbitmap_for_each_set(&hctx->ctx_map, flush_busy_ctx, &data);
}
EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs);
static inline unsigned int queued_to_index(unsigned int queued)
{
if (!queued)
return 0;
return min(BLK_MQ_MAX_DISPATCH_ORDER - 1, ilog2(queued) + 1);
}
static bool blk_mq_get_driver_tag(struct request *rq,
struct blk_mq_hw_ctx **hctx, bool wait)
{
struct blk_mq_alloc_data data = {
.q = rq->q,
.ctx = rq->mq_ctx,
.hctx = blk_mq_map_queue(rq->q, rq->mq_ctx->cpu),
.flags = wait ? 0 : BLK_MQ_REQ_NOWAIT,
};
if (blk_mq_hctx_stopped(data.hctx))
return false;
if (rq->tag != -1) {
done:
if (hctx)
*hctx = data.hctx;
return true;
}
rq->tag = blk_mq_get_tag(&data);
if (rq->tag >= 0) {
if (blk_mq_tag_busy(data.hctx)) {
rq->rq_flags |= RQF_MQ_INFLIGHT;
atomic_inc(&data.hctx->nr_active);
}
data.hctx->tags->rqs[rq->tag] = rq;
goto done;
}
return false;
}
/*
* If we fail getting a driver tag because all the driver tags are already
* assigned and on the dispatch list, BUT the first entry does not have a
* tag, then we could deadlock. For that case, move entries with assigned
* driver tags to the front, leaving the set of tagged requests in the
* same order, and the untagged set in the same order.
*/
static bool reorder_tags_to_front(struct list_head *list)
{
struct request *rq, *tmp, *first = NULL;
list_for_each_entry_safe_reverse(rq, tmp, list, queuelist) {
if (rq == first)
break;
if (rq->tag != -1) {
list_move(&rq->queuelist, list);
if (!first)
first = rq;
}
}
return first != NULL;
}
bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list)
{
struct request_queue *q = hctx->queue;
struct request *rq;
LIST_HEAD(driver_list);
struct list_head *dptr;
int queued, ret = BLK_MQ_RQ_QUEUE_OK;
/*
* Start off with dptr being NULL, so we start the first request
* immediately, even if we have more pending.
*/
dptr = NULL;
/*
* Now process all the entries, sending them to the driver.
*/
queued = 0;
while (!list_empty(list)) {
struct blk_mq_queue_data bd;
rq = list_first_entry(list, struct request, queuelist);
if (!blk_mq_get_driver_tag(rq, &hctx, false)) {
if (!queued && reorder_tags_to_front(list))
continue;
blk_mq_sched_mark_restart(hctx);
break;
}
list_del_init(&rq->queuelist);
bd.rq = rq;
bd.list = dptr;
bd.last = list_empty(list);
ret = q->mq_ops->queue_rq(hctx, &bd);
switch (ret) {
case BLK_MQ_RQ_QUEUE_OK:
queued++;
break;
case BLK_MQ_RQ_QUEUE_BUSY:
list_add(&rq->queuelist, list);
__blk_mq_requeue_request(rq);
break;
default:
pr_err("blk-mq: bad return on queue: %d\n", ret);
case BLK_MQ_RQ_QUEUE_ERROR:
rq->errors = -EIO;
blk_mq_end_request(rq, rq->errors);
break;
}
if (ret == BLK_MQ_RQ_QUEUE_BUSY)
break;
/*
* We've done the first request. If we have more than 1
* left in the list, set dptr to defer issue.
*/
if (!dptr && list->next != list->prev)
dptr = &driver_list;
}
hctx->dispatched[queued_to_index(queued)]++;
/*
* Any items that need requeuing? Stuff them into hctx->dispatch,
* that is where we will continue on next queue run.
*/
if (!list_empty(list)) {
spin_lock(&hctx->lock);
list_splice(list, &hctx->dispatch);
spin_unlock(&hctx->lock);
/*
* the queue is expected stopped with BLK_MQ_RQ_QUEUE_BUSY, but
* it's possible the queue is stopped and restarted again
* before this. Queue restart will dispatch requests. And since
* requests in rq_list aren't added into hctx->dispatch yet,
* the requests in rq_list might get lost.
*
* blk_mq_run_hw_queue() already checks the STOPPED bit
*
* If RESTART is set, then let completion restart the queue
* instead of potentially looping here.
*/
if (!blk_mq_sched_needs_restart(hctx))
blk_mq_run_hw_queue(hctx, true);
}
return ret != BLK_MQ_RQ_QUEUE_BUSY;
}
static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
{
int srcu_idx;
WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask) &&
cpu_online(hctx->next_cpu));
if (!(hctx->flags & BLK_MQ_F_BLOCKING)) {
rcu_read_lock();
blk_mq_sched_dispatch_requests(hctx);
rcu_read_unlock();
} else {
srcu_idx = srcu_read_lock(&hctx->queue_rq_srcu);
blk_mq_sched_dispatch_requests(hctx);
srcu_read_unlock(&hctx->queue_rq_srcu, srcu_idx);
}
}
/*
* It'd be great if the workqueue API had a way to pass
* in a mask and had some smarts for more clever placement.
* For now we just round-robin here, switching for every
* BLK_MQ_CPU_WORK_BATCH queued items.
*/
static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx)
{
if (hctx->queue->nr_hw_queues == 1)
return WORK_CPU_UNBOUND;
if (--hctx->next_cpu_batch <= 0) {
int next_cpu;
next_cpu = cpumask_next(hctx->next_cpu, hctx->cpumask);
if (next_cpu >= nr_cpu_ids)
next_cpu = cpumask_first(hctx->cpumask);
hctx->next_cpu = next_cpu;
hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
}
return hctx->next_cpu;
}
void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
{
if (unlikely(blk_mq_hctx_stopped(hctx) ||
!blk_mq_hw_queue_mapped(hctx)))
return;
if (!async && !(hctx->flags & BLK_MQ_F_BLOCKING)) {
int cpu = get_cpu();
if (cpumask_test_cpu(cpu, hctx->cpumask)) {
__blk_mq_run_hw_queue(hctx);
put_cpu();
return;
}
put_cpu();
}
kblockd_schedule_work_on(blk_mq_hctx_next_cpu(hctx), &hctx->run_work);
}
void blk_mq_run_hw_queues(struct request_queue *q, bool async)
{
struct blk_mq_hw_ctx *hctx;
int i;
queue_for_each_hw_ctx(q, hctx, i) {
if (!blk_mq_hctx_has_pending(hctx) ||
blk_mq_hctx_stopped(hctx))
continue;
blk_mq_run_hw_queue(hctx, async);
}
}
EXPORT_SYMBOL(blk_mq_run_hw_queues);
/**
* blk_mq_queue_stopped() - check whether one or more hctxs have been stopped
* @q: request queue.
*
* The caller is responsible for serializing this function against
* blk_mq_{start,stop}_hw_queue().
*/
bool blk_mq_queue_stopped(struct request_queue *q)
{
struct blk_mq_hw_ctx *hctx;
int i;
queue_for_each_hw_ctx(q, hctx, i)
if (blk_mq_hctx_stopped(hctx))
return true;
return false;
}
EXPORT_SYMBOL(blk_mq_queue_stopped);
void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
{
cancel_work(&hctx->run_work);
cancel_delayed_work(&hctx->delay_work);
set_bit(BLK_MQ_S_STOPPED, &hctx->state);
}
EXPORT_SYMBOL(blk_mq_stop_hw_queue);
void blk_mq_stop_hw_queues(struct request_queue *q)
{
struct blk_mq_hw_ctx *hctx;
int i;
queue_for_each_hw_ctx(q, hctx, i)
blk_mq_stop_hw_queue(hctx);
}
EXPORT_SYMBOL(blk_mq_stop_hw_queues);
void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx)
{
clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
blk_mq_run_hw_queue(hctx, false);
}
EXPORT_SYMBOL(blk_mq_start_hw_queue);
void blk_mq_start_hw_queues(struct request_queue *q)
{
struct blk_mq_hw_ctx *hctx;
int i;
queue_for_each_hw_ctx(q, hctx, i)
blk_mq_start_hw_queue(hctx);
}
EXPORT_SYMBOL(blk_mq_start_hw_queues);
void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
{
if (!blk_mq_hctx_stopped(hctx))
return;
clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
blk_mq_run_hw_queue(hctx, async);
}
EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue);
void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async)
{
struct blk_mq_hw_ctx *hctx;
int i;
queue_for_each_hw_ctx(q, hctx, i)
blk_mq_start_stopped_hw_queue(hctx, async);
}
EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues);
static void blk_mq_run_work_fn(struct work_struct *work)
{
struct blk_mq_hw_ctx *hctx;
hctx = container_of(work, struct blk_mq_hw_ctx, run_work);
__blk_mq_run_hw_queue(hctx);
}
static void blk_mq_delay_work_fn(struct work_struct *work)
{
struct blk_mq_hw_ctx *hctx;
hctx = container_of(work, struct blk_mq_hw_ctx, delay_work.work);
if (test_and_clear_bit(BLK_MQ_S_STOPPED, &hctx->state))
__blk_mq_run_hw_queue(hctx);
}
void blk_mq_delay_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
{
if (unlikely(!blk_mq_hw_queue_mapped(hctx)))
return;
blk_mq_stop_hw_queue(hctx);
kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx),
&hctx->delay_work, msecs_to_jiffies(msecs));
}
EXPORT_SYMBOL(blk_mq_delay_queue);
static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx *hctx,
struct request *rq,
bool at_head)
{
struct blk_mq_ctx *ctx = rq->mq_ctx;
trace_block_rq_insert(hctx->queue, rq);
if (at_head)
list_add(&rq->queuelist, &ctx->rq_list);
else
list_add_tail(&rq->queuelist, &ctx->rq_list);
}
void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
bool at_head)
{
struct blk_mq_ctx *ctx = rq->mq_ctx;
__blk_mq_insert_req_list(hctx, rq, at_head);
blk_mq_hctx_mark_pending(hctx, ctx);
}
void blk_mq_insert_requests(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
struct list_head *list)
{
/*
* preemption doesn't flush plug list, so it's possible ctx->cpu is
* offline now
*/
spin_lock(&ctx->lock);
while (!list_empty(list)) {
struct request *rq;
rq = list_first_entry(list, struct request, queuelist);
BUG_ON(rq->mq_ctx != ctx);
list_del_init(&rq->queuelist);
__blk_mq_insert_req_list(hctx, rq, false);
}
blk_mq_hctx_mark_pending(hctx, ctx);
spin_unlock(&ctx->lock);
}
static int plug_ctx_cmp(void *priv, struct list_head *a, struct list_head *b)
{
struct request *rqa = container_of(a, struct request, queuelist);
struct request *rqb = container_of(b, struct request, queuelist);
return !(rqa->mq_ctx < rqb->mq_ctx ||
(rqa->mq_ctx == rqb->mq_ctx &&
blk_rq_pos(rqa) < blk_rq_pos(rqb)));
}
void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
{
struct blk_mq_ctx *this_ctx;
struct request_queue *this_q;
struct request *rq;
LIST_HEAD(list);
LIST_HEAD(ctx_list);
unsigned int depth;
list_splice_init(&plug->mq_list, &list);
list_sort(NULL, &list, plug_ctx_cmp);
this_q = NULL;
this_ctx = NULL;
depth = 0;
while (!list_empty(&list)) {
rq = list_entry_rq(list.next);
list_del_init(&rq->queuelist);
BUG_ON(!rq->q);
if (rq->mq_ctx != this_ctx) {
if (this_ctx) {
trace_block_unplug(this_q, depth, from_schedule);
blk_mq_sched_insert_requests(this_q, this_ctx,
&ctx_list,
from_schedule);
}
this_ctx = rq->mq_ctx;
this_q = rq->q;
depth = 0;
}
depth++;
list_add_tail(&rq->queuelist, &ctx_list);
}
/*
* If 'this_ctx' is set, we know we have entries to complete
* on 'ctx_list'. Do those.
*/
if (this_ctx) {
trace_block_unplug(this_q, depth, from_schedule);
blk_mq_sched_insert_requests(this_q, this_ctx, &ctx_list,
from_schedule);
}
}
static void blk_mq_bio_to_request(struct request *rq, struct bio *bio)
{
init_request_from_bio(rq, bio);
blk_account_io_start(rq, true);
}
static inline bool hctx_allow_merges(struct blk_mq_hw_ctx *hctx)
{
return (hctx->flags & BLK_MQ_F_SHOULD_MERGE) &&
!blk_queue_nomerges(hctx->queue);
}
static inline bool blk_mq_merge_queue_io(struct blk_mq_hw_ctx *hctx,
struct blk_mq_ctx *ctx,
struct request *rq, struct bio *bio)
{
if (!hctx_allow_merges(hctx) || !bio_mergeable(bio)) {
blk_mq_bio_to_request(rq, bio);
spin_lock(&ctx->lock);
insert_rq:
__blk_mq_insert_request(hctx, rq, false);
spin_unlock(&ctx->lock);
return false;
} else {
struct request_queue *q = hctx->queue;
spin_lock(&ctx->lock);
if (!blk_mq_attempt_merge(q, ctx, bio)) {
blk_mq_bio_to_request(rq, bio);
goto insert_rq;
}
spin_unlock(&ctx->lock);
__blk_mq_finish_request(hctx, ctx, rq);
return true;
}
}
static blk_qc_t request_to_qc_t(struct blk_mq_hw_ctx *hctx, struct request *rq)
{
if (rq->tag != -1)
return blk_tag_to_qc_t(rq->tag, hctx->queue_num, false);
return blk_tag_to_qc_t(rq->internal_tag, hctx->queue_num, true);
}
static void blk_mq_try_issue_directly(struct request *rq, blk_qc_t *cookie)
{
struct request_queue *q = rq->q;
struct blk_mq_queue_data bd = {
.rq = rq,
.list = NULL,
.last = 1
};
struct blk_mq_hw_ctx *hctx;
blk_qc_t new_cookie;
int ret;
if (q->elevator)
goto insert;
if (!blk_mq_get_driver_tag(rq, &hctx, false))
goto insert;
new_cookie = request_to_qc_t(hctx, rq);
/*
* For OK queue, we are done. For error, kill it. Any other
* error (busy), just add it to our list as we previously
* would have done
*/
ret = q->mq_ops->queue_rq(hctx, &bd);
if (ret == BLK_MQ_RQ_QUEUE_OK) {
*cookie = new_cookie;
return;
}
__blk_mq_requeue_request(rq);
if (ret == BLK_MQ_RQ_QUEUE_ERROR) {
*cookie = BLK_QC_T_NONE;
rq->errors = -EIO;
blk_mq_end_request(rq, rq->errors);
return;
}
insert:
blk_mq_sched_insert_request(rq, false, true, true);
}
/*
* Multiple hardware queue variant. This will not use per-process plugs,
* but will attempt to bypass the hctx queueing if we can go straight to
* hardware for SYNC IO.
*/
static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
{
const int is_sync = op_is_sync(bio->bi_opf);
const int is_flush_fua = bio->bi_opf & (REQ_PREFLUSH | REQ_FUA);
struct blk_mq_alloc_data data;
struct request *rq;
unsigned int request_count = 0, srcu_idx;
struct blk_plug *plug;
struct request *same_queue_rq = NULL;
blk_qc_t cookie;
unsigned int wb_acct;
blk_queue_bounce(q, &bio);
if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
bio_io_error(bio);
return BLK_QC_T_NONE;
}
blk_queue_split(q, &bio, q->bio_split);
if (!is_flush_fua && !blk_queue_nomerges(q) &&
blk_attempt_plug_merge(q, bio, &request_count, &same_queue_rq))
return BLK_QC_T_NONE;
if (blk_mq_sched_bio_merge(q, bio))
return BLK_QC_T_NONE;
wb_acct = wbt_wait(q->rq_wb, bio, NULL);
trace_block_getrq(q, bio, bio->bi_opf);
rq = blk_mq_sched_get_request(q, bio, bio->bi_opf, &data);
if (unlikely(!rq)) {
__wbt_done(q->rq_wb, wb_acct);
return BLK_QC_T_NONE;
}
wbt_track(&rq->issue_stat, wb_acct);
cookie = request_to_qc_t(data.hctx, rq);
if (unlikely(is_flush_fua)) {
blk_mq_bio_to_request(rq, bio);
blk_mq_get_driver_tag(rq, NULL, true);
blk_insert_flush(rq);
goto run_queue;
}
plug = current->plug;
/*
* If the driver supports defer issued based on 'last', then
* queue it up like normal since we can potentially save some
* CPU this way.
*/
if (((plug && !blk_queue_nomerges(q)) || is_sync) &&
!(data.hctx->flags & BLK_MQ_F_DEFER_ISSUE)) {
struct request *old_rq = NULL;
blk_mq_bio_to_request(rq, bio);
/*
* We do limited plugging. If the bio can be merged, do that.
* Otherwise the existing request in the plug list will be
* issued. So the plug list will have one request at most
*/
if (plug) {
/*
* The plug list might get flushed before this. If that
* happens, same_queue_rq is invalid and plug list is
* empty
*/
if (same_queue_rq && !list_empty(&plug->mq_list)) {
old_rq = same_queue_rq;
list_del_init(&old_rq->queuelist);
}
list_add_tail(&rq->queuelist, &plug->mq_list);
} else /* is_sync */
old_rq = rq;
blk_mq_put_ctx(data.ctx);
if (!old_rq)
goto done;
if (!(data.hctx->flags & BLK_MQ_F_BLOCKING)) {
rcu_read_lock();
blk_mq_try_issue_directly(old_rq, &cookie);
rcu_read_unlock();
} else {
srcu_idx = srcu_read_lock(&data.hctx->queue_rq_srcu);
blk_mq_try_issue_directly(old_rq, &cookie);
srcu_read_unlock(&data.hctx->queue_rq_srcu, srcu_idx);
}
goto done;
}
if (q->elevator) {
blk_mq_put_ctx(data.ctx);
blk_mq_bio_to_request(rq, bio);
blk_mq_sched_insert_request(rq, false, true, true);
goto done;
}
if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
/*
* For a SYNC request, send it to the hardware immediately. For
* an ASYNC request, just ensure that we run it later on. The
* latter allows for merging opportunities and more efficient
* dispatching.
*/
run_queue:
blk_mq_run_hw_queue(data.hctx, !is_sync || is_flush_fua);
}
blk_mq_put_ctx(data.ctx);
done:
return cookie;
}
/*
* Single hardware queue variant. This will attempt to use any per-process
* plug for merging and IO deferral.
*/
static blk_qc_t blk_sq_make_request(struct request_queue *q, struct bio *bio)
{
const int is_sync = op_is_sync(bio->bi_opf);
const int is_flush_fua = bio->bi_opf & (REQ_PREFLUSH | REQ_FUA);
struct blk_plug *plug;
unsigned int request_count = 0;
struct blk_mq_alloc_data data;
struct request *rq;
blk_qc_t cookie;
unsigned int wb_acct;
blk_queue_bounce(q, &bio);
if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
bio_io_error(bio);
return BLK_QC_T_NONE;
}
blk_queue_split(q, &bio, q->bio_split);
if (!is_flush_fua && !blk_queue_nomerges(q)) {
if (blk_attempt_plug_merge(q, bio, &request_count, NULL))
return BLK_QC_T_NONE;
} else
request_count = blk_plug_queued_count(q);
if (blk_mq_sched_bio_merge(q, bio))
return BLK_QC_T_NONE;
wb_acct = wbt_wait(q->rq_wb, bio, NULL);
trace_block_getrq(q, bio, bio->bi_opf);
rq = blk_mq_sched_get_request(q, bio, bio->bi_opf, &data);
if (unlikely(!rq)) {
__wbt_done(q->rq_wb, wb_acct);
return BLK_QC_T_NONE;
}
wbt_track(&rq->issue_stat, wb_acct);
cookie = request_to_qc_t(data.hctx, rq);
if (unlikely(is_flush_fua)) {
blk_mq_bio_to_request(rq, bio);
blk_mq_get_driver_tag(rq, NULL, true);
blk_insert_flush(rq);
goto run_queue;
}
/*
* A task plug currently exists. Since this is completely lockless,
* utilize that to temporarily store requests until the task is
* either done or scheduled away.
*/
plug = current->plug;
if (plug) {
struct request *last = NULL;
blk_mq_bio_to_request(rq, bio);
/*
* @request_count may become stale because of schedule
* out, so check the list again.
*/
if (list_empty(&plug->mq_list))
request_count = 0;
if (!request_count)
trace_block_plug(q);
else
last = list_entry_rq(plug->mq_list.prev);
blk_mq_put_ctx(data.ctx);
if (request_count >= BLK_MAX_REQUEST_COUNT || (last &&
blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) {
blk_flush_plug_list(plug, false);
trace_block_plug(q);
}
list_add_tail(&rq->queuelist, &plug->mq_list);
return cookie;
}
if (q->elevator) {
blk_mq_put_ctx(data.ctx);
blk_mq_bio_to_request(rq, bio);
blk_mq_sched_insert_request(rq, false, true, true);
goto done;
}
if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
/*
* For a SYNC request, send it to the hardware immediately. For
* an ASYNC request, just ensure that we run it later on. The
* latter allows for merging opportunities and more efficient
* dispatching.
*/
run_queue:
blk_mq_run_hw_queue(data.hctx, !is_sync || is_flush_fua);
}
blk_mq_put_ctx(data.ctx);
done:
return cookie;
}
void blk_mq_free_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
unsigned int hctx_idx)
{
struct page *page;
if (tags->rqs && set->ops->exit_request) {
int i;
for (i = 0; i < tags->nr_tags; i++) {
struct request *rq = tags->static_rqs[i];
if (!rq)
continue;
set->ops->exit_request(set->driver_data, rq,
hctx_idx, i);
tags->static_rqs[i] = NULL;
}
}
while (!list_empty(&tags->page_list)) {
page = list_first_entry(&tags->page_list, struct page, lru);
list_del_init(&page->lru);
/*
* Remove kmemleak object previously allocated in
* blk_mq_init_rq_map().
*/
kmemleak_free(page_address(page));
__free_pages(page, page->private);
}
}
void blk_mq_free_rq_map(struct blk_mq_tags *tags)
{
kfree(tags->rqs);
tags->rqs = NULL;
kfree(tags->static_rqs);
tags->static_rqs = NULL;
blk_mq_free_tags(tags);
}
struct blk_mq_tags *blk_mq_alloc_rq_map(struct blk_mq_tag_set *set,
unsigned int hctx_idx,
unsigned int nr_tags,
unsigned int reserved_tags)
{
struct blk_mq_tags *tags;
tags = blk_mq_init_tags(nr_tags, reserved_tags,
set->numa_node,
BLK_MQ_FLAG_TO_ALLOC_POLICY(set->flags));
if (!tags)
return NULL;
tags->rqs = kzalloc_node(nr_tags * sizeof(struct request *),
GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
set->numa_node);
if (!tags->rqs) {
blk_mq_free_tags(tags);
return NULL;
}
tags->static_rqs = kzalloc_node(nr_tags * sizeof(struct request *),
GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
set->numa_node);
if (!tags->static_rqs) {
kfree(tags->rqs);
blk_mq_free_tags(tags);
return NULL;
}
return tags;
}
static size_t order_to_size(unsigned int order)
{
return (size_t)PAGE_SIZE << order;
}
int blk_mq_alloc_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
unsigned int hctx_idx, unsigned int depth)
{
unsigned int i, j, entries_per_page, max_order = 4;
size_t rq_size, left;
INIT_LIST_HEAD(&tags->page_list);
/*
* rq_size is the size of the request plus driver payload, rounded
* to the cacheline size
*/
rq_size = round_up(sizeof(struct request) + set->cmd_size,
cache_line_size());
left = rq_size * depth;
for (i = 0; i < depth; ) {
int this_order = max_order;
struct page *page;
int to_do;
void *p;
while (this_order && left < order_to_size(this_order - 1))
this_order--;
do {
page = alloc_pages_node(set->numa_node,
GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY | __GFP_ZERO,
this_order);
if (page)
break;
if (!this_order--)
break;
if (order_to_size(this_order) < rq_size)
break;
} while (1);
if (!page)
goto fail;
page->private = this_order;
list_add_tail(&page->lru, &tags->page_list);
p = page_address(page);
/*
* Allow kmemleak to scan these pages as they contain pointers
* to additional allocations like via ops->init_request().
*/
kmemleak_alloc(p, order_to_size(this_order), 1, GFP_NOIO);
entries_per_page = order_to_size(this_order) / rq_size;
to_do = min(entries_per_page, depth - i);
left -= to_do * rq_size;
for (j = 0; j < to_do; j++) {
struct request *rq = p;
tags->static_rqs[i] = rq;
if (set->ops->init_request) {
if (set->ops->init_request(set->driver_data,
rq, hctx_idx, i,
set->numa_node)) {
tags->static_rqs[i] = NULL;
goto fail;
}
}
p += rq_size;
i++;
}
}
return 0;
fail:
blk_mq_free_rqs(set, tags, hctx_idx);
return -ENOMEM;
}
/*
* 'cpu' is going away. splice any existing rq_list entries from this
* software queue to the hw queue dispatch list, and ensure that it
* gets run.
*/
static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node)
{
struct blk_mq_hw_ctx *hctx;
struct blk_mq_ctx *ctx;
LIST_HEAD(tmp);
hctx = hlist_entry_safe(node, struct blk_mq_hw_ctx, cpuhp_dead);
ctx = __blk_mq_get_ctx(hctx->queue, cpu);
spin_lock(&ctx->lock);
if (!list_empty(&ctx->rq_list)) {
list_splice_init(&ctx->rq_list, &tmp);
blk_mq_hctx_clear_pending(hctx, ctx);
}
spin_unlock(&ctx->lock);
if (list_empty(&tmp))
return 0;
spin_lock(&hctx->lock);
list_splice_tail_init(&tmp, &hctx->dispatch);
spin_unlock(&hctx->lock);
blk_mq_run_hw_queue(hctx, true);
return 0;
}
static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx *hctx)
{
cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD,
&hctx->cpuhp_dead);
}
/* hctx->ctxs will be freed in queue's release handler */
static void blk_mq_exit_hctx(struct request_queue *q,
struct blk_mq_tag_set *set,
struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
{
unsigned flush_start_tag = set->queue_depth;
blk_mq_tag_idle(hctx);
if (set->ops->exit_request)
set->ops->exit_request(set->driver_data,
hctx->fq->flush_rq, hctx_idx,
flush_start_tag + hctx_idx);
if (set->ops->exit_hctx)
set->ops->exit_hctx(hctx, hctx_idx);
if (hctx->flags & BLK_MQ_F_BLOCKING)
cleanup_srcu_struct(&hctx->queue_rq_srcu);
blk_mq_remove_cpuhp(hctx);
blk_free_flush_queue(hctx->fq);
sbitmap_free(&hctx->ctx_map);
}
static void blk_mq_exit_hw_queues(struct request_queue *q,
struct blk_mq_tag_set *set, int nr_queue)
{
struct blk_mq_hw_ctx *hctx;
unsigned int i;
queue_for_each_hw_ctx(q, hctx, i) {
if (i == nr_queue)
break;
blk_mq_exit_hctx(q, set, hctx, i);
}
}
static void blk_mq_free_hw_queues(struct request_queue *q,
struct blk_mq_tag_set *set)
{
struct blk_mq_hw_ctx *hctx;
unsigned int i;
queue_for_each_hw_ctx(q, hctx, i)
free_cpumask_var(hctx->cpumask);
}
static int blk_mq_init_hctx(struct request_queue *q,
struct blk_mq_tag_set *set,
struct blk_mq_hw_ctx *hctx, unsigned hctx_idx)
{
int node;
unsigned flush_start_tag = set->queue_depth;
node = hctx->numa_node;
if (node == NUMA_NO_NODE)
node = hctx->numa_node = set->numa_node;
INIT_WORK(&hctx->run_work, blk_mq_run_work_fn);
INIT_DELAYED_WORK(&hctx->delay_work, blk_mq_delay_work_fn);
spin_lock_init(&hctx->lock);
INIT_LIST_HEAD(&hctx->dispatch);
hctx->queue = q;
hctx->queue_num = hctx_idx;
hctx->flags = set->flags & ~BLK_MQ_F_TAG_SHARED;
cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD, &hctx->cpuhp_dead);
hctx->tags = set->tags[hctx_idx];
/*
* Allocate space for all possible cpus to avoid allocation at
* runtime
*/
hctx->ctxs = kmalloc_node(nr_cpu_ids * sizeof(void *),
GFP_KERNEL, node);
if (!hctx->ctxs)
goto unregister_cpu_notifier;
if (sbitmap_init_node(&hctx->ctx_map, nr_cpu_ids, ilog2(8), GFP_KERNEL,
node))
goto free_ctxs;
hctx->nr_ctx = 0;
if (set->ops->init_hctx &&
set->ops->init_hctx(hctx, set->driver_data, hctx_idx))
goto free_bitmap;
hctx->fq = blk_alloc_flush_queue(q, hctx->numa_node, set->cmd_size);
if (!hctx->fq)
goto exit_hctx;
if (set->ops->init_request &&
set->ops->init_request(set->driver_data,
hctx->fq->flush_rq, hctx_idx,
flush_start_tag + hctx_idx, node))
goto free_fq;
if (hctx->flags & BLK_MQ_F_BLOCKING)
init_srcu_struct(&hctx->queue_rq_srcu);
return 0;
free_fq:
kfree(hctx->fq);
exit_hctx:
if (set->ops->exit_hctx)
set->ops->exit_hctx(hctx, hctx_idx);
free_bitmap:
sbitmap_free(&hctx->ctx_map);
free_ctxs:
kfree(hctx->ctxs);
unregister_cpu_notifier:
blk_mq_remove_cpuhp(hctx);
return -1;
}
static void blk_mq_init_cpu_queues(struct request_queue *q,
unsigned int nr_hw_queues)
{
unsigned int i;
for_each_possible_cpu(i) {
struct blk_mq_ctx *__ctx = per_cpu_ptr(q->queue_ctx, i);
struct blk_mq_hw_ctx *hctx;
memset(__ctx, 0, sizeof(*__ctx));
__ctx->cpu = i;
spin_lock_init(&__ctx->lock);
INIT_LIST_HEAD(&__ctx->rq_list);
__ctx->queue = q;
blk_stat_init(&__ctx->stat[BLK_STAT_READ]);
blk_stat_init(&__ctx->stat[BLK_STAT_WRITE]);
/* If the cpu isn't online, the cpu is mapped to first hctx */
if (!cpu_online(i))
continue;
hctx = blk_mq_map_queue(q, i);
/*
* Set local node, IFF we have more than one hw queue. If
* not, we remain on the home node of the device
*/
if (nr_hw_queues > 1 && hctx->numa_node == NUMA_NO_NODE)
hctx->numa_node = local_memory_node(cpu_to_node(i));
}
}
static bool __blk_mq_alloc_rq_map(struct blk_mq_tag_set *set, int hctx_idx)
{
int ret = 0;
set->tags[hctx_idx] = blk_mq_alloc_rq_map(set, hctx_idx,
set->queue_depth, set->reserved_tags);
if (!set->tags[hctx_idx])
return false;
ret = blk_mq_alloc_rqs(set, set->tags[hctx_idx], hctx_idx,
set->queue_depth);
if (!ret)
return true;
blk_mq_free_rq_map(set->tags[hctx_idx]);
set->tags[hctx_idx] = NULL;
return false;
}
static void blk_mq_free_map_and_requests(struct blk_mq_tag_set *set,
unsigned int hctx_idx)
{
if (set->tags[hctx_idx]) {
blk_mq_free_rqs(set, set->tags[hctx_idx], hctx_idx);
blk_mq_free_rq_map(set->tags[hctx_idx]);
set->tags[hctx_idx] = NULL;
}
}
static void blk_mq_map_swqueue(struct request_queue *q,
const struct cpumask *online_mask)
{
unsigned int i, hctx_idx;
struct blk_mq_hw_ctx *hctx;
struct blk_mq_ctx *ctx;
struct blk_mq_tag_set *set = q->tag_set;
/*
* Avoid others reading imcomplete hctx->cpumask through sysfs
*/
mutex_lock(&q->sysfs_lock);
queue_for_each_hw_ctx(q, hctx, i) {
cpumask_clear(hctx->cpumask);
hctx->nr_ctx = 0;
}
/*
* Map software to hardware queues
*/
for_each_possible_cpu(i) {
/* If the cpu isn't online, the cpu is mapped to first hctx */
if (!cpumask_test_cpu(i, online_mask))
continue;
hctx_idx = q->mq_map[i];
/* unmapped hw queue can be remapped after CPU topo changed */
if (!set->tags[hctx_idx] &&
!__blk_mq_alloc_rq_map(set, hctx_idx)) {
/*
* If tags initialization fail for some hctx,
* that hctx won't be brought online. In this
* case, remap the current ctx to hctx[0] which
* is guaranteed to always have tags allocated
*/
q->mq_map[i] = 0;
}
ctx = per_cpu_ptr(q->queue_ctx, i);
hctx = blk_mq_map_queue(q, i);
cpumask_set_cpu(i, hctx->cpumask);
ctx->index_hw = hctx->nr_ctx;
hctx->ctxs[hctx->nr_ctx++] = ctx;
}
mutex_unlock(&q->sysfs_lock);
queue_for_each_hw_ctx(q, hctx, i) {
/*
* If no software queues are mapped to this hardware queue,
* disable it and free the request entries.
*/
if (!hctx->nr_ctx) {
/* Never unmap queue 0. We need it as a
* fallback in case of a new remap fails
* allocation
*/
if (i && set->tags[i])
blk_mq_free_map_and_requests(set, i);
hctx->tags = NULL;
continue;
}
hctx->tags = set->tags[i];
WARN_ON(!hctx->tags);
/*
* Set the map size to the number of mapped software queues.
* This is more accurate and more efficient than looping
* over all possibly mapped software queues.
*/
sbitmap_resize(&hctx->ctx_map, hctx->nr_ctx);
/*
* Initialize batch roundrobin counts
*/
hctx->next_cpu = cpumask_first(hctx->cpumask);
hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
}
}
static void queue_set_hctx_shared(struct request_queue *q, bool shared)
{
struct blk_mq_hw_ctx *hctx;
int i;
queue_for_each_hw_ctx(q, hctx, i) {
if (shared)
hctx->flags |= BLK_MQ_F_TAG_SHARED;
else
hctx->flags &= ~BLK_MQ_F_TAG_SHARED;
}
}
static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set *set, bool shared)
{
struct request_queue *q;
list_for_each_entry(q, &set->tag_list, tag_set_list) {
blk_mq_freeze_queue(q);
queue_set_hctx_shared(q, shared);
blk_mq_unfreeze_queue(q);
}
}
static void blk_mq_del_queue_tag_set(struct request_queue *q)
{
struct blk_mq_tag_set *set = q->tag_set;
mutex_lock(&set->tag_list_lock);
list_del_init(&q->tag_set_list);
if (list_is_singular(&set->tag_list)) {
/* just transitioned to unshared */
set->flags &= ~BLK_MQ_F_TAG_SHARED;
/* update existing queue */
blk_mq_update_tag_set_depth(set, false);
}
mutex_unlock(&set->tag_list_lock);
}
static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
struct request_queue *q)
{
q->tag_set = set;
mutex_lock(&set->tag_list_lock);
/* Check to see if we're transitioning to shared (from 1 to 2 queues). */
if (!list_empty(&set->tag_list) && !(set->flags & BLK_MQ_F_TAG_SHARED)) {
set->flags |= BLK_MQ_F_TAG_SHARED;
/* update existing queue */
blk_mq_update_tag_set_depth(set, true);
}
if (set->flags & BLK_MQ_F_TAG_SHARED)
queue_set_hctx_shared(q, true);
list_add_tail(&q->tag_set_list, &set->tag_list);
mutex_unlock(&set->tag_list_lock);
}
/*
* It is the actual release handler for mq, but we do it from
* request queue's release handler for avoiding use-after-free
* and headache because q->mq_kobj shouldn't have been introduced,
* but we can't group ctx/kctx kobj without it.
*/
void blk_mq_release(struct request_queue *q)
{
struct blk_mq_hw_ctx *hctx;
unsigned int i;
blk_mq_sched_teardown(q);
/* hctx kobj stays in hctx */
queue_for_each_hw_ctx(q, hctx, i) {
if (!hctx)
continue;
kfree(hctx->ctxs);
kfree(hctx);
}
q->mq_map = NULL;
kfree(q->queue_hw_ctx);
/* ctx kobj stays in queue_ctx */
free_percpu(q->queue_ctx);
}
struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
{
struct request_queue *uninit_q, *q;
uninit_q = blk_alloc_queue_node(GFP_KERNEL, set->numa_node);
if (!uninit_q)
return ERR_PTR(-ENOMEM);
q = blk_mq_init_allocated_queue(set, uninit_q);
if (IS_ERR(q))
blk_cleanup_queue(uninit_q);
return q;
}
EXPORT_SYMBOL(blk_mq_init_queue);
static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
struct request_queue *q)
{
int i, j;
struct blk_mq_hw_ctx **hctxs = q->queue_hw_ctx;
blk_mq_sysfs_unregister(q);
for (i = 0; i < set->nr_hw_queues; i++) {
int node;
if (hctxs[i])
continue;
node = blk_mq_hw_queue_to_node(q->mq_map, i);
hctxs[i] = kzalloc_node(sizeof(struct blk_mq_hw_ctx),
GFP_KERNEL, node);
if (!hctxs[i])
break;
if (!zalloc_cpumask_var_node(&hctxs[i]->cpumask, GFP_KERNEL,
node)) {
kfree(hctxs[i]);
hctxs[i] = NULL;
break;
}
atomic_set(&hctxs[i]->nr_active, 0);
hctxs[i]->numa_node = node;
hctxs[i]->queue_num = i;
if (blk_mq_init_hctx(q, set, hctxs[i], i)) {
free_cpumask_var(hctxs[i]->cpumask);
kfree(hctxs[i]);
hctxs[i] = NULL;
break;
}
blk_mq_hctx_kobj_init(hctxs[i]);
}
for (j = i; j < q->nr_hw_queues; j++) {
struct blk_mq_hw_ctx *hctx = hctxs[j];
if (hctx) {
if (hctx->tags)
blk_mq_free_map_and_requests(set, j);
blk_mq_exit_hctx(q, set, hctx, j);
free_cpumask_var(hctx->cpumask);
kobject_put(&hctx->kobj);
kfree(hctx->ctxs);
kfree(hctx);
hctxs[j] = NULL;
}
}
q->nr_hw_queues = i;
blk_mq_sysfs_register(q);
}
struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
struct request_queue *q)
{
/* mark the queue as mq asap */
q->mq_ops = set->ops;
q->queue_ctx = alloc_percpu(struct blk_mq_ctx);
if (!q->queue_ctx)
goto err_exit;
q->queue_hw_ctx = kzalloc_node(nr_cpu_ids * sizeof(*(q->queue_hw_ctx)),
GFP_KERNEL, set->numa_node);
if (!q->queue_hw_ctx)
goto err_percpu;
q->mq_map = set->mq_map;
blk_mq_realloc_hw_ctxs(set, q);
if (!q->nr_hw_queues)
goto err_hctxs;
INIT_WORK(&q->timeout_work, blk_mq_timeout_work);
blk_queue_rq_timeout(q, set->timeout ? set->timeout : 30 * HZ);
q->nr_queues = nr_cpu_ids;
q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
if (!(set->flags & BLK_MQ_F_SG_MERGE))
q->queue_flags |= 1 << QUEUE_FLAG_NO_SG_MERGE;
q->sg_reserved_size = INT_MAX;
INIT_DELAYED_WORK(&q->requeue_work, blk_mq_requeue_work);
INIT_LIST_HEAD(&q->requeue_list);
spin_lock_init(&q->requeue_lock);
if (q->nr_hw_queues > 1)
blk_queue_make_request(q, blk_mq_make_request);
else
blk_queue_make_request(q, blk_sq_make_request);
/*
* Do this after blk_queue_make_request() overrides it...
*/
q->nr_requests = set->queue_depth;
/*
* Default to classic polling
*/
q->poll_nsec = -1;
if (set->ops->complete)
blk_queue_softirq_done(q, set->ops->complete);
blk_mq_init_cpu_queues(q, set->nr_hw_queues);
get_online_cpus();
mutex_lock(&all_q_mutex);
list_add_tail(&q->all_q_node, &all_q_list);
blk_mq_add_queue_tag_set(set, q);
blk_mq_map_swqueue(q, cpu_online_mask);
mutex_unlock(&all_q_mutex);
put_online_cpus();
if (!(set->flags & BLK_MQ_F_NO_SCHED)) {
int ret;
ret = blk_mq_sched_init(q);
if (ret)
return ERR_PTR(ret);
}
return q;
err_hctxs:
kfree(q->queue_hw_ctx);
err_percpu:
free_percpu(q->queue_ctx);
err_exit:
q->mq_ops = NULL;
return ERR_PTR(-ENOMEM);
}
EXPORT_SYMBOL(blk_mq_init_allocated_queue);
void blk_mq_free_queue(struct request_queue *q)
{
struct blk_mq_tag_set *set = q->tag_set;
mutex_lock(&all_q_mutex);
list_del_init(&q->all_q_node);
mutex_unlock(&all_q_mutex);
wbt_exit(q);
blk_mq_del_queue_tag_set(q);
blk_mq_exit_hw_queues(q, set, set->nr_hw_queues);
blk_mq_free_hw_queues(q, set);
}
/* Basically redo blk_mq_init_queue with queue frozen */
static void blk_mq_queue_reinit(struct request_queue *q,
const struct cpumask *online_mask)
{
WARN_ON_ONCE(!atomic_read(&q->mq_freeze_depth));
blk_mq_sysfs_unregister(q);
/*
* redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
* we should change hctx numa_node according to new topology (this
* involves free and re-allocate memory, worthy doing?)
*/
blk_mq_map_swqueue(q, online_mask);
blk_mq_sysfs_register(q);
}
/*
* New online cpumask which is going to be set in this hotplug event.
* Declare this cpumasks as global as cpu-hotplug operation is invoked
* one-by-one and dynamically allocating this could result in a failure.
*/
static struct cpumask cpuhp_online_new;
static void blk_mq_queue_reinit_work(void)
{
struct request_queue *q;
mutex_lock(&all_q_mutex);
/*
* We need to freeze and reinit all existing queues. Freezing
* involves synchronous wait for an RCU grace period and doing it
* one by one may take a long time. Start freezing all queues in
* one swoop and then wait for the completions so that freezing can
* take place in parallel.
*/
list_for_each_entry(q, &all_q_list, all_q_node)
blk_mq_freeze_queue_start(q);
list_for_each_entry(q, &all_q_list, all_q_node)
blk_mq_freeze_queue_wait(q);
list_for_each_entry(q, &all_q_list, all_q_node)
blk_mq_queue_reinit(q, &cpuhp_online_new);
list_for_each_entry(q, &all_q_list, all_q_node)
blk_mq_unfreeze_queue(q);
mutex_unlock(&all_q_mutex);
}
static int blk_mq_queue_reinit_dead(unsigned int cpu)
{
cpumask_copy(&cpuhp_online_new, cpu_online_mask);
blk_mq_queue_reinit_work();
return 0;
}
/*
* Before hotadded cpu starts handling requests, new mappings must be
* established. Otherwise, these requests in hw queue might never be
* dispatched.
*
* For example, there is a single hw queue (hctx) and two CPU queues (ctx0
* for CPU0, and ctx1 for CPU1).
*
* Now CPU1 is just onlined and a request is inserted into ctx1->rq_list
* and set bit0 in pending bitmap as ctx1->index_hw is still zero.
*
* And then while running hw queue, blk_mq_flush_busy_ctxs() finds bit0 is set
* in pending bitmap and tries to retrieve requests in hctx->ctxs[0]->rq_list.
* But htx->ctxs[0] is a pointer to ctx0, so the request in ctx1->rq_list is
* ignored.
*/
static int blk_mq_queue_reinit_prepare(unsigned int cpu)
{
cpumask_copy(&cpuhp_online_new, cpu_online_mask);
cpumask_set_cpu(cpu, &cpuhp_online_new);
blk_mq_queue_reinit_work();
return 0;
}
static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
{
int i;
for (i = 0; i < set->nr_hw_queues; i++)
if (!__blk_mq_alloc_rq_map(set, i))
goto out_unwind;
return 0;
out_unwind:
while (--i >= 0)
blk_mq_free_rq_map(set->tags[i]);
return -ENOMEM;
}
/*
* Allocate the request maps associated with this tag_set. Note that this
* may reduce the depth asked for, if memory is tight. set->queue_depth
* will be updated to reflect the allocated depth.
*/
static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
{
unsigned int depth;
int err;
depth = set->queue_depth;
do {
err = __blk_mq_alloc_rq_maps(set);
if (!err)
break;
set->queue_depth >>= 1;
if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN) {
err = -ENOMEM;
break;
}
} while (set->queue_depth);
if (!set->queue_depth || err) {
pr_err("blk-mq: failed to allocate request map\n");
return -ENOMEM;
}
if (depth != set->queue_depth)
pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
depth, set->queue_depth);
return 0;
}
/*
* Alloc a tag set to be associated with one or more request queues.
* May fail with EINVAL for various error conditions. May adjust the
* requested depth down, if if it too large. In that case, the set
* value will be stored in set->queue_depth.
*/
int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
{
int ret;
BUILD_BUG_ON(BLK_MQ_MAX_DEPTH > 1 << BLK_MQ_UNIQUE_TAG_BITS);
if (!set->nr_hw_queues)
return -EINVAL;
if (!set->queue_depth)
return -EINVAL;
if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN)
return -EINVAL;
if (!set->ops->queue_rq)
return -EINVAL;
if (set->queue_depth > BLK_MQ_MAX_DEPTH) {
pr_info("blk-mq: reduced tag depth to %u\n",
BLK_MQ_MAX_DEPTH);
set->queue_depth = BLK_MQ_MAX_DEPTH;
}
/*
* If a crashdump is active, then we are potentially in a very
* memory constrained environment. Limit us to 1 queue and
* 64 tags to prevent using too much memory.
*/
if (is_kdump_kernel()) {
set->nr_hw_queues = 1;
set->queue_depth = min(64U, set->queue_depth);
}
/*
* There is no use for more h/w queues than cpus.
*/
if (set->nr_hw_queues > nr_cpu_ids)
set->nr_hw_queues = nr_cpu_ids;
set->tags = kzalloc_node(nr_cpu_ids * sizeof(struct blk_mq_tags *),
GFP_KERNEL, set->numa_node);
if (!set->tags)
return -ENOMEM;
ret = -ENOMEM;
set->mq_map = kzalloc_node(sizeof(*set->mq_map) * nr_cpu_ids,
GFP_KERNEL, set->numa_node);
if (!set->mq_map)
goto out_free_tags;
if (set->ops->map_queues)
ret = set->ops->map_queues(set);
else
ret = blk_mq_map_queues(set);
if (ret)
goto out_free_mq_map;
ret = blk_mq_alloc_rq_maps(set);
if (ret)
goto out_free_mq_map;
mutex_init(&set->tag_list_lock);
INIT_LIST_HEAD(&set->tag_list);
return 0;
out_free_mq_map:
kfree(set->mq_map);
set->mq_map = NULL;
out_free_tags:
kfree(set->tags);
set->tags = NULL;
return ret;
}
EXPORT_SYMBOL(blk_mq_alloc_tag_set);
void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
{
int i;
for (i = 0; i < nr_cpu_ids; i++)
blk_mq_free_map_and_requests(set, i);
kfree(set->mq_map);
set->mq_map = NULL;
kfree(set->tags);
set->tags = NULL;
}
EXPORT_SYMBOL(blk_mq_free_tag_set);
int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
{
struct blk_mq_tag_set *set = q->tag_set;
struct blk_mq_hw_ctx *hctx;
int i, ret;
if (!set)
return -EINVAL;
blk_mq_freeze_queue(q);
blk_mq_quiesce_queue(q);
ret = 0;
queue_for_each_hw_ctx(q, hctx, i) {
if (!hctx->tags)
continue;
/*
* If we're using an MQ scheduler, just update the scheduler
* queue depth. This is similar to what the old code would do.
*/
if (!hctx->sched_tags) {
ret = blk_mq_tag_update_depth(hctx, &hctx->tags,
min(nr, set->queue_depth),
false);
} else {
ret = blk_mq_tag_update_depth(hctx, &hctx->sched_tags,
nr, true);
}
if (ret)
break;
}
if (!ret)
q->nr_requests = nr;
blk_mq_unfreeze_queue(q);
blk_mq_start_stopped_hw_queues(q, true);
return ret;
}
void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues)
{
struct request_queue *q;
if (nr_hw_queues > nr_cpu_ids)
nr_hw_queues = nr_cpu_ids;
if (nr_hw_queues < 1 || nr_hw_queues == set->nr_hw_queues)
return;
list_for_each_entry(q, &set->tag_list, tag_set_list)
blk_mq_freeze_queue(q);
set->nr_hw_queues = nr_hw_queues;
list_for_each_entry(q, &set->tag_list, tag_set_list) {
blk_mq_realloc_hw_ctxs(set, q);
if (q->nr_hw_queues > 1)
blk_queue_make_request(q, blk_mq_make_request);
else
blk_queue_make_request(q, blk_sq_make_request);
blk_mq_queue_reinit(q, cpu_online_mask);
}
list_for_each_entry(q, &set->tag_list, tag_set_list)
blk_mq_unfreeze_queue(q);
}
EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues);
static unsigned long blk_mq_poll_nsecs(struct request_queue *q,
struct blk_mq_hw_ctx *hctx,
struct request *rq)
{
struct blk_rq_stat stat[2];
unsigned long ret = 0;
/*
* If stats collection isn't on, don't sleep but turn it on for
* future users
*/
if (!blk_stat_enable(q))
return 0;
/*
* We don't have to do this once per IO, should optimize this
* to just use the current window of stats until it changes
*/
memset(&stat, 0, sizeof(stat));
blk_hctx_stat_get(hctx, stat);
/*
* As an optimistic guess, use half of the mean service time
* for this type of request. We can (and should) make this smarter.
* For instance, if the completion latencies are tight, we can
* get closer than just half the mean. This is especially
* important on devices where the completion latencies are longer
* than ~10 usec.
*/
if (req_op(rq) == REQ_OP_READ && stat[BLK_STAT_READ].nr_samples)
ret = (stat[BLK_STAT_READ].mean + 1) / 2;
else if (req_op(rq) == REQ_OP_WRITE && stat[BLK_STAT_WRITE].nr_samples)
ret = (stat[BLK_STAT_WRITE].mean + 1) / 2;
return ret;
}
static bool blk_mq_poll_hybrid_sleep(struct request_queue *q,
struct blk_mq_hw_ctx *hctx,
struct request *rq)
{
struct hrtimer_sleeper hs;
enum hrtimer_mode mode;
unsigned int nsecs;
ktime_t kt;
if (test_bit(REQ_ATOM_POLL_SLEPT, &rq->atomic_flags))
return false;
/*
* poll_nsec can be:
*
* -1: don't ever hybrid sleep
* 0: use half of prev avg
* >0: use this specific value
*/
if (q->poll_nsec == -1)
return false;
else if (q->poll_nsec > 0)
nsecs = q->poll_nsec;
else
nsecs = blk_mq_poll_nsecs(q, hctx, rq);
if (!nsecs)
return false;
set_bit(REQ_ATOM_POLL_SLEPT, &rq->atomic_flags);
/*
* This will be replaced with the stats tracking code, using
* 'avg_completion_time / 2' as the pre-sleep target.
*/
kt = nsecs;
mode = HRTIMER_MODE_REL;
hrtimer_init_on_stack(&hs.timer, CLOCK_MONOTONIC, mode);
hrtimer_set_expires(&hs.timer, kt);
hrtimer_init_sleeper(&hs, current);
do {
if (test_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags))
break;
set_current_state(TASK_UNINTERRUPTIBLE);
hrtimer_start_expires(&hs.timer, mode);
if (hs.task)
io_schedule();
hrtimer_cancel(&hs.timer);
mode = HRTIMER_MODE_ABS;
} while (hs.task && !signal_pending(current));
__set_current_state(TASK_RUNNING);
destroy_hrtimer_on_stack(&hs.timer);
return true;
}
static bool __blk_mq_poll(struct blk_mq_hw_ctx *hctx, struct request *rq)
{
struct request_queue *q = hctx->queue;
long state;
/*
* If we sleep, have the caller restart the poll loop to reset
* the state. Like for the other success return cases, the
* caller is responsible for checking if the IO completed. If
* the IO isn't complete, we'll get called again and will go
* straight to the busy poll loop.
*/
if (blk_mq_poll_hybrid_sleep(q, hctx, rq))
return true;
hctx->poll_considered++;
state = current->state;
while (!need_resched()) {
int ret;
hctx->poll_invoked++;
ret = q->mq_ops->poll(hctx, rq->tag);
if (ret > 0) {
hctx->poll_success++;
set_current_state(TASK_RUNNING);
return true;
}
if (signal_pending_state(state, current))
set_current_state(TASK_RUNNING);
if (current->state == TASK_RUNNING)
return true;
if (ret < 0)
break;
cpu_relax();
}
return false;
}
bool blk_mq_poll(struct request_queue *q, blk_qc_t cookie)
{
struct blk_mq_hw_ctx *hctx;
struct blk_plug *plug;
struct request *rq;
if (!q->mq_ops || !q->mq_ops->poll || !blk_qc_t_valid(cookie) ||
!test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
return false;
plug = current->plug;
if (plug)
blk_flush_plug_list(plug, false);
hctx = q->queue_hw_ctx[blk_qc_t_to_queue_num(cookie)];
if (!blk_qc_t_is_internal(cookie))
rq = blk_mq_tag_to_rq(hctx->tags, blk_qc_t_to_tag(cookie));
else
rq = blk_mq_tag_to_rq(hctx->sched_tags, blk_qc_t_to_tag(cookie));
return __blk_mq_poll(hctx, rq);
}
EXPORT_SYMBOL_GPL(blk_mq_poll);
void blk_mq_disable_hotplug(void)
{
mutex_lock(&all_q_mutex);
}
void blk_mq_enable_hotplug(void)
{
mutex_unlock(&all_q_mutex);
}
static int __init blk_mq_init(void)
{
cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD, "block/mq:dead", NULL,
blk_mq_hctx_notify_dead);
cpuhp_setup_state_nocalls(CPUHP_BLK_MQ_PREPARE, "block/mq:prepare",
blk_mq_queue_reinit_prepare,
blk_mq_queue_reinit_dead);
return 0;
}
subsys_initcall(blk_mq_init);