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4ab32bf330
linux/block/blk-mq.c
Jens Axboe 4ab32bf330 blk-mq: never redirect polled IO completions 
It's pointless to do so, we are by definition on the CPU we want/need
to be, as that's the one waiting for a completion event.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-26 08:26:04 -07:00

3422 lines
82 KiB
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/*
* 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/sched/topology.h>
#include <linux/sched/signal.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-debugfs.h"
#include "blk-mq-tag.h"
#include "blk-pm.h"
#include "blk-stat.h"
#include "blk-mq-sched.h"
#include "blk-rq-qos.h"
static int blk_mq_poll(struct request_queue *q, blk_qc_t cookie, bool spin);
static void blk_mq_poll_stats_start(struct request_queue *q);
static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb);
static int blk_mq_poll_stats_bkt(const struct request *rq)
{
int ddir, bytes, bucket;
ddir = rq_data_dir(rq);
bytes = blk_rq_bytes(rq);
bucket = ddir + 2*(ilog2(bytes) - 9);
if (bucket < 0)
return -1;
else if (bucket >= BLK_MQ_POLL_STATS_BKTS)
return ddir + BLK_MQ_POLL_STATS_BKTS - 2;
return bucket;
}
/*
* 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 !list_empty_careful(&hctx->dispatch) ||
sbitmap_any_bit_set(&hctx->ctx_map) ||
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)
{
const int bit = ctx->index_hw[hctx->type];
if (!sbitmap_test_bit(&hctx->ctx_map, bit))
sbitmap_set_bit(&hctx->ctx_map, bit);
}
static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx *hctx,
struct blk_mq_ctx *ctx)
{
const int bit = ctx->index_hw[hctx->type];
sbitmap_clear_bit(&hctx->ctx_map, bit);
}
struct mq_inflight {
struct hd_struct *part;
unsigned int *inflight;
};
static bool blk_mq_check_inflight(struct blk_mq_hw_ctx *hctx,
struct request *rq, void *priv,
bool reserved)
{
struct mq_inflight *mi = priv;
/*
* index[0] counts the specific partition that was asked for. index[1]
* counts the ones that are active on the whole device, so increment
* that if mi->part is indeed a partition, and not a whole device.
*/
if (rq->part == mi->part)
mi->inflight[0]++;
if (mi->part->partno)
mi->inflight[1]++;
return true;
}
void blk_mq_in_flight(struct request_queue *q, struct hd_struct *part,
unsigned int inflight[2])
{
struct mq_inflight mi = { .part = part, .inflight = inflight, };
inflight[0] = inflight[1] = 0;
blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight, &mi);
}
static bool blk_mq_check_inflight_rw(struct blk_mq_hw_ctx *hctx,
struct request *rq, void *priv,
bool reserved)
{
struct mq_inflight *mi = priv;
if (rq->part == mi->part)
mi->inflight[rq_data_dir(rq)]++;
return true;
}
void blk_mq_in_flight_rw(struct request_queue *q, struct hd_struct *part,
unsigned int inflight[2])
{
struct mq_inflight mi = { .part = part, .inflight = inflight, };
inflight[0] = inflight[1] = 0;
blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight_rw, &mi);
}
void blk_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);
if (queue_is_mq(q))
blk_mq_run_hw_queues(q, false);
}
}
EXPORT_SYMBOL_GPL(blk_freeze_queue_start);
void blk_mq_freeze_queue_wait(struct request_queue *q)
{
wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->q_usage_counter));
}
EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait);
int blk_mq_freeze_queue_wait_timeout(struct request_queue *q,
unsigned long timeout)
{
return wait_event_timeout(q->mq_freeze_wq,
percpu_ref_is_zero(&q->q_usage_counter),
timeout);
}
EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait_timeout);
/*
* 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_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_resurrect(&q->q_usage_counter);
wake_up_all(&q->mq_freeze_wq);
}
}
EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue);
/*
* FIXME: replace the scsi_internal_device_*block_nowait() calls in the
* mpt3sas driver such that this function can be removed.
*/
void blk_mq_quiesce_queue_nowait(struct request_queue *q)
{
blk_queue_flag_set(QUEUE_FLAG_QUIESCED, q);
}
EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait);
/**
* blk_mq_quiesce_queue() - wait until all ongoing dispatches have finished
* @q: request queue.
*
* Note: this function does not prevent that the struct request end_io()
* callback function is invoked. Once this function is returned, we make
* sure no dispatch can happen until the queue is unquiesced via
* blk_mq_unquiesce_queue().
*/
void blk_mq_quiesce_queue(struct request_queue *q)
{
struct blk_mq_hw_ctx *hctx;
unsigned int i;
bool rcu = false;
blk_mq_quiesce_queue_nowait(q);
queue_for_each_hw_ctx(q, hctx, i) {
if (hctx->flags & BLK_MQ_F_BLOCKING)
synchronize_srcu(hctx->srcu);
else
rcu = true;
}
if (rcu)
synchronize_rcu();
}
EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue);
/*
* blk_mq_unquiesce_queue() - counterpart of blk_mq_quiesce_queue()
* @q: request queue.
*
* This function recovers queue into the state before quiescing
* which is done by blk_mq_quiesce_queue.
*/
void blk_mq_unquiesce_queue(struct request_queue *q)
{
blk_queue_flag_clear(QUEUE_FLAG_QUIESCED, q);
/* dispatch requests which are inserted during quiescing */
blk_mq_run_hw_queues(q, true);
}
EXPORT_SYMBOL_GPL(blk_mq_unquiesce_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);
}
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);
static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,
unsigned int tag, unsigned int op)
{
struct blk_mq_tags *tags = blk_mq_tags_from_data(data);
struct request *rq = tags->static_rqs[tag];
req_flags_t rq_flags = 0;
if (data->flags & BLK_MQ_REQ_INTERNAL) {
rq->tag = -1;
rq->internal_tag = tag;
} else {
if (data->hctx->flags & BLK_MQ_F_TAG_SHARED) {
rq_flags = RQF_MQ_INFLIGHT;
atomic_inc(&data->hctx->nr_active);
}
rq->tag = tag;
rq->internal_tag = -1;
data->hctx->tags->rqs[rq->tag] = rq;
}
/* csd/requeue_work/fifo_time is initialized before use */
rq->q = data->q;
rq->mq_ctx = data->ctx;
rq->mq_hctx = data->hctx;
rq->rq_flags = rq_flags;
rq->cmd_flags = op;
if (data->flags & BLK_MQ_REQ_PREEMPT)
rq->rq_flags |= RQF_PREEMPT;
if (blk_queue_io_stat(data->q))
rq->rq_flags |= RQF_IO_STAT;
INIT_LIST_HEAD(&rq->queuelist);
INIT_HLIST_NODE(&rq->hash);
RB_CLEAR_NODE(&rq->rb_node);
rq->rq_disk = NULL;
rq->part = NULL;
rq->start_time_ns = ktime_get_ns();
rq->io_start_time_ns = 0;
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->extra_len = 0;
WRITE_ONCE(rq->deadline, 0);
rq->timeout = 0;
rq->end_io = NULL;
rq->end_io_data = NULL;
rq->next_rq = NULL;
data->ctx->rq_dispatched[op_is_sync(op)]++;
refcount_set(&rq->ref, 1);
return rq;
}
static struct request *blk_mq_get_request(struct request_queue *q,
struct bio *bio,
struct blk_mq_alloc_data *data)
{
struct elevator_queue *e = q->elevator;
struct request *rq;
unsigned int tag;
bool put_ctx_on_error = false;
blk_queue_enter_live(q);
data->q = q;
if (likely(!data->ctx)) {
data->ctx = blk_mq_get_ctx(q);
put_ctx_on_error = true;
}
if (likely(!data->hctx))
data->hctx = blk_mq_map_queue(q, data->cmd_flags,
data->ctx->cpu);
if (data->cmd_flags & REQ_NOWAIT)
data->flags |= BLK_MQ_REQ_NOWAIT;
if (e) {
data->flags |= BLK_MQ_REQ_INTERNAL;
/*
* Flush requests are special and go directly to the
* dispatch list. Don't include reserved tags in the
* limiting, as it isn't useful.
*/
if (!op_is_flush(data->cmd_flags) &&
e->type->ops.limit_depth &&
!(data->flags & BLK_MQ_REQ_RESERVED))
e->type->ops.limit_depth(data->cmd_flags, data);
} else {
blk_mq_tag_busy(data->hctx);
}
tag = blk_mq_get_tag(data);
if (tag == BLK_MQ_TAG_FAIL) {
if (put_ctx_on_error) {
blk_mq_put_ctx(data->ctx);
data->ctx = NULL;
}
blk_queue_exit(q);
return NULL;
}
rq = blk_mq_rq_ctx_init(data, tag, data->cmd_flags);
if (!op_is_flush(data->cmd_flags)) {
rq->elv.icq = NULL;
if (e && e->type->ops.prepare_request) {
if (e->type->icq_cache)
blk_mq_sched_assign_ioc(rq);
e->type->ops.prepare_request(rq, bio);
rq->rq_flags |= RQF_ELVPRIV;
}
}
data->hctx->queued++;
return rq;
}
struct request *blk_mq_alloc_request(struct request_queue *q, unsigned int op,
blk_mq_req_flags_t flags)
{
struct blk_mq_alloc_data alloc_data = { .flags = flags, .cmd_flags = op };
struct request *rq;
int ret;
ret = blk_queue_enter(q, flags);
if (ret)
return ERR_PTR(ret);
rq = blk_mq_get_request(q, NULL, &alloc_data);
blk_queue_exit(q);
if (!rq)
return ERR_PTR(-EWOULDBLOCK);
blk_mq_put_ctx(alloc_data.ctx);
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,
unsigned int op, blk_mq_req_flags_t flags, unsigned int hctx_idx)
{
struct blk_mq_alloc_data alloc_data = { .flags = flags, .cmd_flags = op };
struct request *rq;
unsigned int cpu;
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, flags);
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.
*/
alloc_data.hctx = q->queue_hw_ctx[hctx_idx];
if (!blk_mq_hw_queue_mapped(alloc_data.hctx)) {
blk_queue_exit(q);
return ERR_PTR(-EXDEV);
}
cpu = cpumask_first_and(alloc_data.hctx->cpumask, cpu_online_mask);
alloc_data.ctx = __blk_mq_get_ctx(q, cpu);
rq = blk_mq_get_request(q, NULL, &alloc_data);
blk_queue_exit(q);
if (!rq)
return ERR_PTR(-EWOULDBLOCK);
return rq;
}
EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx);
static void __blk_mq_free_request(struct request *rq)
{
struct request_queue *q = rq->q;
struct blk_mq_ctx *ctx = rq->mq_ctx;
struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
const int sched_tag = rq->internal_tag;
blk_pm_mark_last_busy(rq);
rq->mq_hctx = NULL;
if (rq->tag != -1)
blk_mq_put_tag(hctx, hctx->tags, ctx, rq->tag);
if (sched_tag != -1)
blk_mq_put_tag(hctx, hctx->sched_tags, ctx, sched_tag);
blk_mq_sched_restart(hctx);
blk_queue_exit(q);
}
void blk_mq_free_request(struct request *rq)
{
struct request_queue *q = rq->q;
struct elevator_queue *e = q->elevator;
struct blk_mq_ctx *ctx = rq->mq_ctx;
struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
if (rq->rq_flags & RQF_ELVPRIV) {
if (e && e->type->ops.finish_request)
e->type->ops.finish_request(rq);
if (rq->elv.icq) {
put_io_context(rq->elv.icq->ioc);
rq->elv.icq = NULL;
}
}
ctx->rq_completed[rq_is_sync(rq)]++;
if (rq->rq_flags & RQF_MQ_INFLIGHT)
atomic_dec(&hctx->nr_active);
if (unlikely(laptop_mode && !blk_rq_is_passthrough(rq)))
laptop_io_completion(q->backing_dev_info);
rq_qos_done(q, rq);
WRITE_ONCE(rq->state, MQ_RQ_IDLE);
if (refcount_dec_and_test(&rq->ref))
__blk_mq_free_request(rq);
}
EXPORT_SYMBOL_GPL(blk_mq_free_request);
inline void __blk_mq_end_request(struct request *rq, blk_status_t error)
{
u64 now = ktime_get_ns();
if (rq->rq_flags & RQF_STATS) {
blk_mq_poll_stats_start(rq->q);
blk_stat_add(rq, now);
}
if (rq->internal_tag != -1)
blk_mq_sched_completed_request(rq, now);
blk_account_io_done(rq, now);
if (rq->end_io) {
rq_qos_done(rq->q, rq);
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, blk_status_t 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;
struct request_queue *q = rq->q;
q->mq_ops->complete(rq);
}
static void __blk_mq_complete_request(struct request *rq)
{
struct blk_mq_ctx *ctx = rq->mq_ctx;
struct request_queue *q = rq->q;
bool shared = false;
int cpu;
if (!blk_mq_mark_complete(rq))
return;
/*
* Most of single queue controllers, there is only one irq vector
* for handling IO completion, and the only irq's affinity is set
* as all possible CPUs. On most of ARCHs, this affinity means the
* irq is handled on one specific CPU.
*
* So complete IO reqeust in softirq context in case of single queue
* for not degrading IO performance by irqsoff latency.
*/
if (q->nr_hw_queues == 1) {
__blk_complete_request(rq);
return;
}
/*
* For a polled request, always complete locallly, it's pointless
* to redirect the completion.
*/
if ((rq->cmd_flags & REQ_HIPRI) ||
!test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags)) {
q->mq_ops->complete(rq);
return;
}
cpu = get_cpu();
if (!test_bit(QUEUE_FLAG_SAME_FORCE, &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 {
q->mq_ops->complete(rq);
}
put_cpu();
}
static void hctx_unlock(struct blk_mq_hw_ctx *hctx, int srcu_idx)
__releases(hctx->srcu)
{
if (!(hctx->flags & BLK_MQ_F_BLOCKING))
rcu_read_unlock();
else
srcu_read_unlock(hctx->srcu, srcu_idx);
}
static void hctx_lock(struct blk_mq_hw_ctx *hctx, int *srcu_idx)
__acquires(hctx->srcu)
{
if (!(hctx->flags & BLK_MQ_F_BLOCKING)) {
/* shut up gcc false positive */
*srcu_idx = 0;
rcu_read_lock();
} else
*srcu_idx = srcu_read_lock(hctx->srcu);
}
/**
* 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)
{
if (unlikely(blk_should_fake_timeout(rq->q)))
return;
__blk_mq_complete_request(rq);
}
EXPORT_SYMBOL(blk_mq_complete_request);
int blk_mq_request_started(struct request *rq)
{
return blk_mq_rq_state(rq) != MQ_RQ_IDLE;
}
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);
if (test_bit(QUEUE_FLAG_STATS, &q->queue_flags)) {
rq->io_start_time_ns = ktime_get_ns();
#ifdef CONFIG_BLK_DEV_THROTTLING_LOW
rq->throtl_size = blk_rq_sectors(rq);
#endif
rq->rq_flags |= RQF_STATS;
rq_qos_issue(q, rq);
}
WARN_ON_ONCE(blk_mq_rq_state(rq) != MQ_RQ_IDLE);
blk_add_timer(rq);
WRITE_ONCE(rq->state, MQ_RQ_IN_FLIGHT);
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;
blk_mq_put_driver_tag(rq);
trace_block_rq_requeue(q, rq);
rq_qos_requeue(q, rq);
if (blk_mq_request_started(rq)) {
WRITE_ONCE(rq->state, MQ_RQ_IDLE);
rq->rq_flags &= ~RQF_TIMED_OUT;
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);
/* this request will be re-inserted to io scheduler queue */
blk_mq_sched_requeue_request(rq);
BUG_ON(!list_empty(&rq->queuelist));
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;
spin_lock_irq(&q->requeue_lock);
list_splice_init(&q->requeue_list, &rq_list);
spin_unlock_irq(&q->requeue_lock);
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 insertion 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_mod_delayed_work_on(WORK_CPU_UNBOUND, &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_mod_delayed_work_on(WORK_CPU_UNBOUND, &q->requeue_work,
msecs_to_jiffies(msecs));
}
EXPORT_SYMBOL(blk_mq_delay_kick_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);
static bool blk_mq_check_busy(struct blk_mq_hw_ctx *hctx, struct request *rq,
void *priv, bool reserved)
{
/*
* If we find a request, we know the queue is busy. Return false
* to stop the iteration.
*/
if (rq->q == hctx->queue) {
bool *busy = priv;
*busy = true;
return false;
}
return true;
}
bool blk_mq_queue_busy(struct request_queue *q)
{
bool busy = false;
blk_mq_queue_tag_busy_iter(q, blk_mq_check_busy, &busy);
return busy;
}
EXPORT_SYMBOL_GPL(blk_mq_queue_busy);
static void blk_mq_rq_timed_out(struct request *req, bool reserved)
{
req->rq_flags |= RQF_TIMED_OUT;
if (req->q->mq_ops->timeout) {
enum blk_eh_timer_return ret;
ret = req->q->mq_ops->timeout(req, reserved);
if (ret == BLK_EH_DONE)
return;
WARN_ON_ONCE(ret != BLK_EH_RESET_TIMER);
}
blk_add_timer(req);
}
static bool blk_mq_req_expired(struct request *rq, unsigned long *next)
{
unsigned long deadline;
if (blk_mq_rq_state(rq) != MQ_RQ_IN_FLIGHT)
return false;
if (rq->rq_flags & RQF_TIMED_OUT)
return false;
deadline = READ_ONCE(rq->deadline);
if (time_after_eq(jiffies, deadline))
return true;
if (*next == 0)
*next = deadline;
else if (time_after(*next, deadline))
*next = deadline;
return false;
}
static bool blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
struct request *rq, void *priv, bool reserved)
{
unsigned long *next = priv;
/*
* Just do a quick check if it is expired before locking the request in
* so we're not unnecessarilly synchronizing across CPUs.
*/
if (!blk_mq_req_expired(rq, next))
return true;
/*
* We have reason to believe the request may be expired. Take a
* reference on the request to lock this request lifetime into its
* currently allocated context to prevent it from being reallocated in
* the event the completion by-passes this timeout handler.
*
* If the reference was already released, then the driver beat the
* timeout handler to posting a natural completion.
*/
if (!refcount_inc_not_zero(&rq->ref))
return true;
/*
* The request is now locked and cannot be reallocated underneath the
* timeout handler's processing. Re-verify this exact request is truly
* expired; if it is not expired, then the request was completed and
* reallocated as a new request.
*/
if (blk_mq_req_expired(rq, next))
blk_mq_rq_timed_out(rq, reserved);
if (refcount_dec_and_test(&rq->ref))
__blk_mq_free_request(rq);
return true;
}
static void blk_mq_timeout_work(struct work_struct *work)
{
struct request_queue *q =
container_of(work, struct request_queue, timeout_work);
unsigned long next = 0;
struct blk_mq_hw_ctx *hctx;
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_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, &next);
if (next != 0) {
mod_timer(&q->timeout, next);
} else {
/*
* Request timeouts are handled as a forward rolling timer. If
* we end up here it means that no requests are pending and
* also that no request has been pending for a while. Mark
* each hctx as idle.
*/
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);
}
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];
spin_lock(&ctx->lock);
list_splice_tail_init(&ctx->rq_list, flush_data->list);
sbitmap_clear_bit(sb, bitnr);
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);
struct dispatch_rq_data {
struct blk_mq_hw_ctx *hctx;
struct request *rq;
};
static bool dispatch_rq_from_ctx(struct sbitmap *sb, unsigned int bitnr,
void *data)
{
struct dispatch_rq_data *dispatch_data = data;
struct blk_mq_hw_ctx *hctx = dispatch_data->hctx;
struct blk_mq_ctx *ctx = hctx->ctxs[bitnr];
spin_lock(&ctx->lock);
if (!list_empty(&ctx->rq_list)) {
dispatch_data->rq = list_entry_rq(ctx->rq_list.next);
list_del_init(&dispatch_data->rq->queuelist);
if (list_empty(&ctx->rq_list))
sbitmap_clear_bit(sb, bitnr);
}
spin_unlock(&ctx->lock);
return !dispatch_data->rq;
}
struct request *blk_mq_dequeue_from_ctx(struct blk_mq_hw_ctx *hctx,
struct blk_mq_ctx *start)
{
unsigned off = start ? start->index_hw[hctx->type] : 0;
struct dispatch_rq_data data = {
.hctx = hctx,
.rq = NULL,
};
__sbitmap_for_each_set(&hctx->ctx_map, off,
dispatch_rq_from_ctx, &data);
return data.rq;
}
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);
}
bool blk_mq_get_driver_tag(struct request *rq)
{
struct blk_mq_alloc_data data = {
.q = rq->q,
.hctx = rq->mq_hctx,
.flags = BLK_MQ_REQ_NOWAIT,
.cmd_flags = rq->cmd_flags,
};
bool shared;
if (rq->tag != -1)
goto done;
if (blk_mq_tag_is_reserved(data.hctx->sched_tags, rq->internal_tag))
data.flags |= BLK_MQ_REQ_RESERVED;
shared = blk_mq_tag_busy(data.hctx);
rq->tag = blk_mq_get_tag(&data);
if (rq->tag >= 0) {
if (shared) {
rq->rq_flags |= RQF_MQ_INFLIGHT;
atomic_inc(&data.hctx->nr_active);
}
data.hctx->tags->rqs[rq->tag] = rq;
}
done:
return rq->tag != -1;
}
static int blk_mq_dispatch_wake(wait_queue_entry_t *wait, unsigned mode,
int flags, void *key)
{
struct blk_mq_hw_ctx *hctx;
hctx = container_of(wait, struct blk_mq_hw_ctx, dispatch_wait);
spin_lock(&hctx->dispatch_wait_lock);
list_del_init(&wait->entry);
spin_unlock(&hctx->dispatch_wait_lock);
blk_mq_run_hw_queue(hctx, true);
return 1;
}
/*
* Mark us waiting for a tag. For shared tags, this involves hooking us into
* the tag wakeups. For non-shared tags, we can simply mark us needing a
* restart. For both cases, take care to check the condition again after
* marking us as waiting.
*/
static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx *hctx,
struct request *rq)
{
struct wait_queue_head *wq;
wait_queue_entry_t *wait;
bool ret;
if (!(hctx->flags & BLK_MQ_F_TAG_SHARED)) {
if (!test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state))
set_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state);
/*
* It's possible that a tag was freed in the window between the
* allocation failure and adding the hardware queue to the wait
* queue.
*
* Don't clear RESTART here, someone else could have set it.
* At most this will cost an extra queue run.
*/
return blk_mq_get_driver_tag(rq);
}
wait = &hctx->dispatch_wait;
if (!list_empty_careful(&wait->entry))
return false;
wq = &bt_wait_ptr(&hctx->tags->bitmap_tags, hctx)->wait;
spin_lock_irq(&wq->lock);
spin_lock(&hctx->dispatch_wait_lock);
if (!list_empty(&wait->entry)) {
spin_unlock(&hctx->dispatch_wait_lock);
spin_unlock_irq(&wq->lock);
return false;
}
wait->flags &= ~WQ_FLAG_EXCLUSIVE;
__add_wait_queue(wq, wait);
/*
* It's possible that a tag was freed in the window between the
* allocation failure and adding the hardware queue to the wait
* queue.
*/
ret = blk_mq_get_driver_tag(rq);
if (!ret) {
spin_unlock(&hctx->dispatch_wait_lock);
spin_unlock_irq(&wq->lock);
return false;
}
/*
* We got a tag, remove ourselves from the wait queue to ensure
* someone else gets the wakeup.
*/
list_del_init(&wait->entry);
spin_unlock(&hctx->dispatch_wait_lock);
spin_unlock_irq(&wq->lock);
return true;
}
#define BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT 8
#define BLK_MQ_DISPATCH_BUSY_EWMA_FACTOR 4
/*
* Update dispatch busy with the Exponential Weighted Moving Average(EWMA):
* - EWMA is one simple way to compute running average value
* - weight(7/8 and 1/8) is applied so that it can decrease exponentially
* - take 4 as factor for avoiding to get too small(0) result, and this
* factor doesn't matter because EWMA decreases exponentially
*/
static void blk_mq_update_dispatch_busy(struct blk_mq_hw_ctx *hctx, bool busy)
{
unsigned int ewma;
if (hctx->queue->elevator)
return;
ewma = hctx->dispatch_busy;
if (!ewma && !busy)
return;
ewma *= BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT - 1;
if (busy)
ewma += 1 << BLK_MQ_DISPATCH_BUSY_EWMA_FACTOR;
ewma /= BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT;
hctx->dispatch_busy = ewma;
}
#define BLK_MQ_RESOURCE_DELAY 3 /* ms units */
/*
* Returns true if we did some work AND can potentially do more.
*/
bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list,
bool got_budget)
{
struct blk_mq_hw_ctx *hctx;
struct request *rq, *nxt;
bool no_tag = false;
int errors, queued;
blk_status_t ret = BLK_STS_OK;
if (list_empty(list))
return false;
WARN_ON(!list_is_singular(list) && got_budget);
/*
* Now process all the entries, sending them to the driver.
*/
errors = queued = 0;
do {
struct blk_mq_queue_data bd;
rq = list_first_entry(list, struct request, queuelist);
hctx = rq->mq_hctx;
if (!got_budget && !blk_mq_get_dispatch_budget(hctx))
break;
if (!blk_mq_get_driver_tag(rq)) {
/*
* The initial allocation attempt failed, so we need to
* rerun the hardware queue when a tag is freed. The
* waitqueue takes care of that. If the queue is run
* before we add this entry back on the dispatch list,
* we'll re-run it below.
*/
if (!blk_mq_mark_tag_wait(hctx, rq)) {
blk_mq_put_dispatch_budget(hctx);
/*
* For non-shared tags, the RESTART check
* will suffice.
*/
if (hctx->flags & BLK_MQ_F_TAG_SHARED)
no_tag = true;
break;
}
}
list_del_init(&rq->queuelist);
bd.rq = rq;
/*
* Flag last if we have no more requests, or if we have more
* but can't assign a driver tag to it.
*/
if (list_empty(list))
bd.last = true;
else {
nxt = list_first_entry(list, struct request, queuelist);
bd.last = !blk_mq_get_driver_tag(nxt);
}
ret = q->mq_ops->queue_rq(hctx, &bd);
if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE) {
/*
* If an I/O scheduler has been configured and we got a
* driver tag for the next request already, free it
* again.
*/
if (!list_empty(list)) {
nxt = list_first_entry(list, struct request, queuelist);
blk_mq_put_driver_tag(nxt);
}
list_add(&rq->queuelist, list);
__blk_mq_requeue_request(rq);
break;
}
if (unlikely(ret != BLK_STS_OK)) {
errors++;
blk_mq_end_request(rq, BLK_STS_IOERR);
continue;
}
queued++;
} while (!list_empty(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)) {
bool needs_restart;
spin_lock(&hctx->lock);
list_splice_init(list, &hctx->dispatch);
spin_unlock(&hctx->lock);
/*
* If SCHED_RESTART was set by the caller of this function and
* it is no longer set that means that it was cleared by another
* thread and hence that a queue rerun is needed.
*
* If 'no_tag' is set, that means that we failed getting
* a driver tag with an I/O scheduler attached. If our dispatch
* waitqueue is no longer active, ensure that we run the queue
* AFTER adding our entries back to the list.
*
* If no I/O scheduler has been configured it is possible that
* the hardware queue got stopped and restarted before requests
* were pushed back onto the dispatch list. Rerun the queue to
* avoid starvation. Notes:
* - blk_mq_run_hw_queue() checks whether or not a queue has
* been stopped before rerunning a queue.
* - Some but not all block drivers stop a queue before
* returning BLK_STS_RESOURCE. Two exceptions are scsi-mq
* and dm-rq.
*
* If driver returns BLK_STS_RESOURCE and SCHED_RESTART
* bit is set, run queue after a delay to avoid IO stalls
* that could otherwise occur if the queue is idle.
*/
needs_restart = blk_mq_sched_needs_restart(hctx);
if (!needs_restart ||
(no_tag && list_empty_careful(&hctx->dispatch_wait.entry)))
blk_mq_run_hw_queue(hctx, true);
else if (needs_restart && (ret == BLK_STS_RESOURCE))
blk_mq_delay_run_hw_queue(hctx, BLK_MQ_RESOURCE_DELAY);
blk_mq_update_dispatch_busy(hctx, true);
return false;
} else
blk_mq_update_dispatch_busy(hctx, false);
/*
* If the host/device is unable to accept more work, inform the
* caller of that.
*/
if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE)
return false;
return (queued + errors) != 0;
}
static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
{
int srcu_idx;
/*
* We should be running this queue from one of the CPUs that
* are mapped to it.
*
* There are at least two related races now between setting
* hctx->next_cpu from blk_mq_hctx_next_cpu() and running
* __blk_mq_run_hw_queue():
*
* - hctx->next_cpu is found offline in blk_mq_hctx_next_cpu(),
* but later it becomes online, then this warning is harmless
* at all
*
* - hctx->next_cpu is found online in blk_mq_hctx_next_cpu(),
* but later it becomes offline, then the warning can't be
* triggered, and we depend on blk-mq timeout handler to
* handle dispatched requests to this hctx
*/
if (!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask) &&
cpu_online(hctx->next_cpu)) {
printk(KERN_WARNING "run queue from wrong CPU %d, hctx %s\n",
raw_smp_processor_id(),
cpumask_empty(hctx->cpumask) ? "inactive": "active");
dump_stack();
}
/*
* We can't run the queue inline with ints disabled. Ensure that
* we catch bad users of this early.
*/
WARN_ON_ONCE(in_interrupt());
might_sleep_if(hctx->flags & BLK_MQ_F_BLOCKING);
hctx_lock(hctx, &srcu_idx);
blk_mq_sched_dispatch_requests(hctx);
hctx_unlock(hctx, srcu_idx);
}
static inline int blk_mq_first_mapped_cpu(struct blk_mq_hw_ctx *hctx)
{
int cpu = cpumask_first_and(hctx->cpumask, cpu_online_mask);
if (cpu >= nr_cpu_ids)
cpu = cpumask_first(hctx->cpumask);
return cpu;
}
/*
* 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)
{
bool tried = false;
int next_cpu = hctx->next_cpu;
if (hctx->queue->nr_hw_queues == 1)
return WORK_CPU_UNBOUND;
if (--hctx->next_cpu_batch <= 0) {
select_cpu:
next_cpu = cpumask_next_and(next_cpu, hctx->cpumask,
cpu_online_mask);
if (next_cpu >= nr_cpu_ids)
next_cpu = blk_mq_first_mapped_cpu(hctx);
hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
}
/*
* Do unbound schedule if we can't find a online CPU for this hctx,
* and it should only happen in the path of handling CPU DEAD.
*/
if (!cpu_online(next_cpu)) {
if (!tried) {
tried = true;
goto select_cpu;
}
/*
* Make sure to re-select CPU next time once after CPUs
* in hctx->cpumask become online again.
*/
hctx->next_cpu = next_cpu;
hctx->next_cpu_batch = 1;
return WORK_CPU_UNBOUND;
}
hctx->next_cpu = next_cpu;
return next_cpu;
}
static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async,
unsigned long msecs)
{
if (unlikely(blk_mq_hctx_stopped(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_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx), &hctx->run_work,
msecs_to_jiffies(msecs));
}
void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
{
__blk_mq_delay_run_hw_queue(hctx, true, msecs);
}
EXPORT_SYMBOL(blk_mq_delay_run_hw_queue);
bool blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
{
int srcu_idx;
bool need_run;
/*
* When queue is quiesced, we may be switching io scheduler, or
* updating nr_hw_queues, or other things, and we can't run queue
* any more, even __blk_mq_hctx_has_pending() can't be called safely.
*
* And queue will be rerun in blk_mq_unquiesce_queue() if it is
* quiesced.
*/
hctx_lock(hctx, &srcu_idx);
need_run = !blk_queue_quiesced(hctx->queue) &&
blk_mq_hctx_has_pending(hctx);
hctx_unlock(hctx, srcu_idx);
if (need_run) {
__blk_mq_delay_run_hw_queue(hctx, async, 0);
return true;
}
return false;
}
EXPORT_SYMBOL(blk_mq_run_hw_queue);
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_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);
/*
* This function is often used for pausing .queue_rq() by driver when
* there isn't enough resource or some conditions aren't satisfied, and
* BLK_STS_RESOURCE is usually returned.
*
* We do not guarantee that dispatch can be drained or blocked
* after blk_mq_stop_hw_queue() returns. Please use
* blk_mq_quiesce_queue() for that requirement.
*/
void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
{
cancel_delayed_work(&hctx->run_work);
set_bit(BLK_MQ_S_STOPPED, &hctx->state);
}
EXPORT_SYMBOL(blk_mq_stop_hw_queue);
/*
* This function is often used for pausing .queue_rq() by driver when
* there isn't enough resource or some conditions aren't satisfied, and
* BLK_STS_RESOURCE is usually returned.
*
* We do not guarantee that dispatch can be drained or blocked
* after blk_mq_stop_hw_queues() returns. Please use
* blk_mq_quiesce_queue() for that requirement.
*/
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.work);
/*
* If we are stopped, don't run the queue.
*/
if (test_bit(BLK_MQ_S_STOPPED, &hctx->state))
return;
__blk_mq_run_hw_queue(hctx);
}
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;
lockdep_assert_held(&ctx->lock);
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;
lockdep_assert_held(&ctx->lock);
__blk_mq_insert_req_list(hctx, rq, at_head);
blk_mq_hctx_mark_pending(hctx, ctx);
}
/*
* Should only be used carefully, when the caller knows we want to
* bypass a potential IO scheduler on the target device.
*/
void blk_mq_request_bypass_insert(struct request *rq, bool run_queue)
{
struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
spin_lock(&hctx->lock);
list_add_tail(&rq->queuelist, &hctx->dispatch);
spin_unlock(&hctx->lock);
if (run_queue)
blk_mq_run_hw_queue(hctx, false);
}
void blk_mq_insert_requests(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
struct list_head *list)
{
struct request *rq;
/*
* preemption doesn't flush plug list, so it's possible ctx->cpu is
* offline now
*/
list_for_each_entry(rq, list, queuelist) {
BUG_ON(rq->mq_ctx != ctx);
trace_block_rq_insert(hctx->queue, rq);
}
spin_lock(&ctx->lock);
list_splice_tail_init(list, &ctx->rq_list);
blk_mq_hctx_mark_pending(hctx, ctx);
spin_unlock(&ctx->lock);
}
static int plug_rq_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);
if (rqa->mq_ctx < rqb->mq_ctx)
return -1;
else if (rqa->mq_ctx > rqb->mq_ctx)
return 1;
else if (rqa->mq_hctx < rqb->mq_hctx)
return -1;
else if (rqa->mq_hctx > rqb->mq_hctx)
return 1;
return blk_rq_pos(rqa) > blk_rq_pos(rqb);
}
void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
{
struct blk_mq_hw_ctx *this_hctx;
struct blk_mq_ctx *this_ctx;
struct request_queue *this_q;
struct request *rq;
LIST_HEAD(list);
LIST_HEAD(rq_list);
unsigned int depth;
list_splice_init(&plug->mq_list, &list);
list_sort(NULL, &list, plug_rq_cmp);
this_q = NULL;
this_hctx = 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_hctx != this_hctx || rq->mq_ctx != this_ctx) {
if (this_hctx) {
trace_block_unplug(this_q, depth, !from_schedule);
blk_mq_sched_insert_requests(this_hctx, this_ctx,
&rq_list,
from_schedule);
}
this_q = rq->q;
this_ctx = rq->mq_ctx;
this_hctx = rq->mq_hctx;
depth = 0;
}
depth++;
list_add_tail(&rq->queuelist, &rq_list);
}
/*
* If 'this_hctx' is set, we know we have entries to complete
* on 'rq_list'. Do those.
*/
if (this_hctx) {
trace_block_unplug(this_q, depth, !from_schedule);
blk_mq_sched_insert_requests(this_hctx, this_ctx, &rq_list,
from_schedule);
}
}
static void blk_mq_bio_to_request(struct request *rq, struct bio *bio)
{
blk_init_request_from_bio(rq, bio);
blk_account_io_start(rq, 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 blk_status_t __blk_mq_issue_directly(struct blk_mq_hw_ctx *hctx,
struct request *rq,
blk_qc_t *cookie)
{
struct request_queue *q = rq->q;
struct blk_mq_queue_data bd = {
.rq = rq,
.last = true,
};
blk_qc_t new_cookie;
blk_status_t ret;
new_cookie = request_to_qc_t(hctx, rq);
/*
* For OK queue, we are done. For error, caller may 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);
switch (ret) {
case BLK_STS_OK:
blk_mq_update_dispatch_busy(hctx, false);
*cookie = new_cookie;
break;
case BLK_STS_RESOURCE:
case BLK_STS_DEV_RESOURCE:
blk_mq_update_dispatch_busy(hctx, true);
__blk_mq_requeue_request(rq);
break;
default:
blk_mq_update_dispatch_busy(hctx, false);
*cookie = BLK_QC_T_NONE;
break;
}
return ret;
}
static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
struct request *rq,
blk_qc_t *cookie,
bool bypass_insert)
{
struct request_queue *q = rq->q;
bool run_queue = true;
/*
* RCU or SRCU read lock is needed before checking quiesced flag.
*
* When queue is stopped or quiesced, ignore 'bypass_insert' from
* blk_mq_request_issue_directly(), and return BLK_STS_OK to caller,
* and avoid driver to try to dispatch again.
*/
if (blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(q)) {
run_queue = false;
bypass_insert = false;
goto insert;
}
if (q->elevator && !bypass_insert)
goto insert;
if (!blk_mq_get_dispatch_budget(hctx))
goto insert;
if (!blk_mq_get_driver_tag(rq)) {
blk_mq_put_dispatch_budget(hctx);
goto insert;
}
return __blk_mq_issue_directly(hctx, rq, cookie);
insert:
if (bypass_insert)
return BLK_STS_RESOURCE;
blk_mq_sched_insert_request(rq, false, run_queue, false);
return BLK_STS_OK;
}
static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
struct request *rq, blk_qc_t *cookie)
{
blk_status_t ret;
int srcu_idx;
might_sleep_if(hctx->flags & BLK_MQ_F_BLOCKING);
hctx_lock(hctx, &srcu_idx);
ret = __blk_mq_try_issue_directly(hctx, rq, cookie, false);
if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE)
blk_mq_sched_insert_request(rq, false, true, false);
else if (ret != BLK_STS_OK)
blk_mq_end_request(rq, ret);
hctx_unlock(hctx, srcu_idx);
}
blk_status_t blk_mq_request_issue_directly(struct request *rq)
{
blk_status_t ret;
int srcu_idx;
blk_qc_t unused_cookie;
struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
hctx_lock(hctx, &srcu_idx);
ret = __blk_mq_try_issue_directly(hctx, rq, &unused_cookie, true);
hctx_unlock(hctx, srcu_idx);
return ret;
}
void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx *hctx,
struct list_head *list)
{
while (!list_empty(list)) {
blk_status_t ret;
struct request *rq = list_first_entry(list, struct request,
queuelist);
list_del_init(&rq->queuelist);
ret = blk_mq_request_issue_directly(rq);
if (ret != BLK_STS_OK) {
if (ret == BLK_STS_RESOURCE ||
ret == BLK_STS_DEV_RESOURCE) {
list_add(&rq->queuelist, list);
break;
}
blk_mq_end_request(rq, ret);
}
}
}
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 = op_is_flush(bio->bi_opf);
struct blk_mq_alloc_data data = { .flags = 0, .cmd_flags = bio->bi_opf };
struct request *rq;
unsigned int request_count = 0;
struct blk_plug *plug;
struct request *same_queue_rq = NULL;
blk_qc_t cookie;
blk_queue_bounce(q, &bio);
blk_queue_split(q, &bio);
if (!bio_integrity_prep(bio))
return BLK_QC_T_NONE;
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;
rq_qos_throttle(q, bio);
rq = blk_mq_get_request(q, bio, &data);
if (unlikely(!rq)) {
rq_qos_cleanup(q, bio);
if (bio->bi_opf & REQ_NOWAIT)
bio_wouldblock_error(bio);
return BLK_QC_T_NONE;
}
trace_block_getrq(q, bio, bio->bi_opf);
rq_qos_track(q, rq, bio);
cookie = request_to_qc_t(data.hctx, rq);
plug = current->plug;
if (unlikely(is_flush_fua)) {
blk_mq_put_ctx(data.ctx);
blk_mq_bio_to_request(rq, bio);
/* bypass scheduler for flush rq */
blk_insert_flush(rq);
blk_mq_run_hw_queue(data.hctx, true);
} else if (plug && q->nr_hw_queues == 1) {
struct request *last = NULL;
blk_mq_put_ctx(data.ctx);
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;
else if (blk_queue_nomerges(q))
request_count = blk_plug_queued_count(q);
if (!request_count)
trace_block_plug(q);
else
last = list_entry_rq(plug->mq_list.prev);
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);
} else if (plug && !blk_queue_nomerges(q)) {
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
* The plug list might get flushed before this. If that happens,
* the plug list is empty, and same_queue_rq is invalid.
*/
if (list_empty(&plug->mq_list))
same_queue_rq = NULL;
if (same_queue_rq)
list_del_init(&same_queue_rq->queuelist);
list_add_tail(&rq->queuelist, &plug->mq_list);
blk_mq_put_ctx(data.ctx);
if (same_queue_rq) {
data.hctx = same_queue_rq->mq_hctx;
blk_mq_try_issue_directly(data.hctx, same_queue_rq,
&cookie);
}
} else if ((q->nr_hw_queues > 1 && is_sync) || (!q->elevator &&
!data.hctx->dispatch_busy)) {
blk_mq_put_ctx(data.ctx);
blk_mq_bio_to_request(rq, bio);
blk_mq_try_issue_directly(data.hctx, rq, &cookie);
} else {
blk_mq_put_ctx(data.ctx);
blk_mq_bio_to_request(rq, bio);
blk_mq_sched_insert_request(rq, false, true, true);
}
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, rq, hctx_idx);
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;
int node;
node = blk_mq_hw_queue_to_node(&set->map[0], hctx_idx);
if (node == NUMA_NO_NODE)
node = set->numa_node;
tags = blk_mq_init_tags(nr_tags, reserved_tags, node,
BLK_MQ_FLAG_TO_ALLOC_POLICY(set->flags));
if (!tags)
return NULL;
tags->rqs = kcalloc_node(nr_tags, sizeof(struct request *),
GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
node);
if (!tags->rqs) {
blk_mq_free_tags(tags);
return NULL;
}
tags->static_rqs = kcalloc_node(nr_tags, sizeof(struct request *),
GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
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;
}
static int blk_mq_init_request(struct blk_mq_tag_set *set, struct request *rq,
unsigned int hctx_idx, int node)
{
int ret;
if (set->ops->init_request) {
ret = set->ops->init_request(set, rq, hctx_idx, node);
if (ret)
return ret;
}
WRITE_ONCE(rq->state, MQ_RQ_IDLE);
return 0;
}
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;
int node;
node = blk_mq_hw_queue_to_node(&set->map[0], hctx_idx);
if (node == NUMA_NO_NODE)
node = set->numa_node;
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(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 (blk_mq_init_request(set, rq, hctx_idx, 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)
{
if (blk_mq_hw_queue_mapped(hctx))
blk_mq_tag_idle(hctx);
if (set->ops->exit_request)
set->ops->exit_request(set, hctx->fq->flush_rq, 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->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_debugfs_unregister_hctx(hctx);
blk_mq_exit_hctx(q, set, hctx, i);
}
}
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;
node = hctx->numa_node;
if (node == NUMA_NO_NODE)
node = hctx->numa_node = set->numa_node;
INIT_DELAYED_WORK(&hctx->run_work, blk_mq_run_work_fn);
spin_lock_init(&hctx->lock);
INIT_LIST_HEAD(&hctx->dispatch);
hctx->queue = q;
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_array_node(nr_cpu_ids, sizeof(void *),
GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY, node);
if (!hctx->ctxs)
goto unregister_cpu_notifier;
if (sbitmap_init_node(&hctx->ctx_map, nr_cpu_ids, ilog2(8),
GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY, node))
goto free_ctxs;
hctx->nr_ctx = 0;
spin_lock_init(&hctx->dispatch_wait_lock);
init_waitqueue_func_entry(&hctx->dispatch_wait, blk_mq_dispatch_wake);
INIT_LIST_HEAD(&hctx->dispatch_wait.entry);
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,
GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY);
if (!hctx->fq)
goto exit_hctx;
if (blk_mq_init_request(set, hctx->fq->flush_rq, hctx_idx, node))
goto free_fq;
if (hctx->flags & BLK_MQ_F_BLOCKING)
init_srcu_struct(hctx->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)
{
struct blk_mq_tag_set *set = q->tag_set;
unsigned int i, j;
for_each_possible_cpu(i) {
struct blk_mq_ctx *__ctx = per_cpu_ptr(q->queue_ctx, i);
struct blk_mq_hw_ctx *hctx;
__ctx->cpu = i;
spin_lock_init(&__ctx->lock);
INIT_LIST_HEAD(&__ctx->rq_list);
__ctx->queue = q;
/*
* Set local node, IFF we have more than one hw queue. If
* not, we remain on the home node of the device
*/
for (j = 0; j < set->nr_maps; j++) {
hctx = blk_mq_map_queue_type(q, j, i);
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)
{
unsigned int i, j, 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;
hctx->dispatch_from = NULL;
}
/*
* Map software to hardware queues.
*
* If the cpu isn't present, the cpu is mapped to first hctx.
*/
for_each_possible_cpu(i) {
hctx_idx = set->map[0].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
*/
set->map[0].mq_map[i] = 0;
}
ctx = per_cpu_ptr(q->queue_ctx, i);
for (j = 0; j < set->nr_maps; j++) {
hctx = blk_mq_map_queue_type(q, j, i);
/*
* If the CPU is already set in the mask, then we've
* mapped this one already. This can happen if
* devices share queues across queue maps.
*/
if (cpumask_test_cpu(i, hctx->cpumask))
continue;
cpumask_set_cpu(i, hctx->cpumask);
hctx->type = j;
ctx->index_hw[hctx->type] = hctx->nr_ctx;
hctx->ctxs[hctx->nr_ctx++] = ctx;
/*
* If the nr_ctx type overflows, we have exceeded the
* amount of sw queues we can support.
*/
BUG_ON(!hctx->nr_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 = blk_mq_first_mapped_cpu(hctx);
hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
}
}
/*
* Caller needs to ensure that we're either frozen/quiesced, or that
* the queue isn't live yet.
*/
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;
lockdep_assert_held(&set->tag_list_lock);
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_rcu(&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);
INIT_LIST_HEAD(&q->tag_set_list);
}
static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
struct request_queue *q)
{
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_rcu(&q->tag_set_list, &set->tag_list);
mutex_unlock(&set->tag_list_lock);
}
/* All allocations will be freed in release handler of q->mq_kobj */
static int blk_mq_alloc_ctxs(struct request_queue *q)
{
struct blk_mq_ctxs *ctxs;
int cpu;
ctxs = kzalloc(sizeof(*ctxs), GFP_KERNEL);
if (!ctxs)
return -ENOMEM;
ctxs->queue_ctx = alloc_percpu(struct blk_mq_ctx);
if (!ctxs->queue_ctx)
goto fail;
for_each_possible_cpu(cpu) {
struct blk_mq_ctx *ctx = per_cpu_ptr(ctxs->queue_ctx, cpu);
ctx->ctxs = ctxs;
}
q->mq_kobj = &ctxs->kobj;
q->queue_ctx = ctxs->queue_ctx;
return 0;
fail:
kfree(ctxs);
return -ENOMEM;
}
/*
* 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;
/* hctx kobj stays in hctx */
queue_for_each_hw_ctx(q, hctx, i) {
if (!hctx)
continue;
kobject_put(&hctx->kobj);
}
kfree(q->queue_hw_ctx);
/*
* release .mq_kobj and sw queue's kobject now because
* both share lifetime with request queue.
*/
blk_mq_sysfs_deinit(q);
}
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);
/*
* Helper for setting up a queue with mq ops, given queue depth, and
* the passed in mq ops flags.
*/
struct request_queue *blk_mq_init_sq_queue(struct blk_mq_tag_set *set,
const struct blk_mq_ops *ops,
unsigned int queue_depth,
unsigned int set_flags)
{
struct request_queue *q;
int ret;
memset(set, 0, sizeof(*set));
set->ops = ops;
set->nr_hw_queues = 1;
set->nr_maps = 1;
set->queue_depth = queue_depth;
set->numa_node = NUMA_NO_NODE;
set->flags = set_flags;
ret = blk_mq_alloc_tag_set(set);
if (ret)
return ERR_PTR(ret);
q = blk_mq_init_queue(set);
if (IS_ERR(q)) {
blk_mq_free_tag_set(set);
return q;
}
return q;
}
EXPORT_SYMBOL(blk_mq_init_sq_queue);
static int blk_mq_hw_ctx_size(struct blk_mq_tag_set *tag_set)
{
int hw_ctx_size = sizeof(struct blk_mq_hw_ctx);
BUILD_BUG_ON(ALIGN(offsetof(struct blk_mq_hw_ctx, srcu),
__alignof__(struct blk_mq_hw_ctx)) !=
sizeof(struct blk_mq_hw_ctx));
if (tag_set->flags & BLK_MQ_F_BLOCKING)
hw_ctx_size += sizeof(struct srcu_struct);
return hw_ctx_size;
}
static struct blk_mq_hw_ctx *blk_mq_alloc_and_init_hctx(
struct blk_mq_tag_set *set, struct request_queue *q,
int hctx_idx, int node)
{
struct blk_mq_hw_ctx *hctx;
hctx = kzalloc_node(blk_mq_hw_ctx_size(set),
GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
node);
if (!hctx)
return NULL;
if (!zalloc_cpumask_var_node(&hctx->cpumask,
GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY,
node)) {
kfree(hctx);
return NULL;
}
atomic_set(&hctx->nr_active, 0);
hctx->numa_node = node;
hctx->queue_num = hctx_idx;
if (blk_mq_init_hctx(q, set, hctx, hctx_idx)) {
free_cpumask_var(hctx->cpumask);
kfree(hctx);
return NULL;
}
blk_mq_hctx_kobj_init(hctx);
return hctx;
}
static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
struct request_queue *q)
{
int i, j, end;
struct blk_mq_hw_ctx **hctxs = q->queue_hw_ctx;
/* protect against switching io scheduler */
mutex_lock(&q->sysfs_lock);
for (i = 0; i < set->nr_hw_queues; i++) {
int node;
struct blk_mq_hw_ctx *hctx;
node = blk_mq_hw_queue_to_node(&set->map[0], i);
/*
* If the hw queue has been mapped to another numa node,
* we need to realloc the hctx. If allocation fails, fallback
* to use the previous one.
*/
if (hctxs[i] && (hctxs[i]->numa_node == node))
continue;
hctx = blk_mq_alloc_and_init_hctx(set, q, i, node);
if (hctx) {
if (hctxs[i]) {
blk_mq_exit_hctx(q, set, hctxs[i], i);
kobject_put(&hctxs[i]->kobj);
}
hctxs[i] = hctx;
} else {
if (hctxs[i])
pr_warn("Allocate new hctx on node %d fails,\
fallback to previous one on node %d\n",
node, hctxs[i]->numa_node);
else
break;
}
}
/*
* Increasing nr_hw_queues fails. Free the newly allocated
* hctxs and keep the previous q->nr_hw_queues.
*/
if (i != set->nr_hw_queues) {
j = q->nr_hw_queues;
end = i;
} else {
j = i;
end = q->nr_hw_queues;
q->nr_hw_queues = set->nr_hw_queues;
}
for (; j < end; 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);
kobject_put(&hctx->kobj);
hctxs[j] = NULL;
}
}
mutex_unlock(&q->sysfs_lock);
}
/*
* Maximum number of hardware queues we support. For single sets, we'll never
* have more than the CPUs (software queues). For multiple sets, the tag_set
* user may have set ->nr_hw_queues larger.
*/
static unsigned int nr_hw_queues(struct blk_mq_tag_set *set)
{
if (set->nr_maps == 1)
return nr_cpu_ids;
return max(set->nr_hw_queues, nr_cpu_ids);
}
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->poll_cb = blk_stat_alloc_callback(blk_mq_poll_stats_fn,
blk_mq_poll_stats_bkt,
BLK_MQ_POLL_STATS_BKTS, q);
if (!q->poll_cb)
goto err_exit;
if (blk_mq_alloc_ctxs(q))
goto err_exit;
/* init q->mq_kobj and sw queues' kobjects */
blk_mq_sysfs_init(q);
q->nr_queues = nr_hw_queues(set);
q->queue_hw_ctx = kcalloc_node(q->nr_queues, sizeof(*(q->queue_hw_ctx)),
GFP_KERNEL, set->numa_node);
if (!q->queue_hw_ctx)
goto err_sys_init;
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->tag_set = set;
q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
if (!(set->flags & BLK_MQ_F_SG_MERGE))
blk_queue_flag_set(QUEUE_FLAG_NO_SG_MERGE, q);
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);
blk_queue_make_request(q, blk_mq_make_request);
if (q->mq_ops->poll)
q->poll_fn = blk_mq_poll;
/*
* Do this after blk_queue_make_request() overrides it...
*/
q->nr_requests = set->queue_depth;
/*
* Default to classic polling
*/
q->poll_nsec = -1;
blk_mq_init_cpu_queues(q, set->nr_hw_queues);
blk_mq_add_queue_tag_set(set, q);
blk_mq_map_swqueue(q);
if (!(set->flags & BLK_MQ_F_NO_SCHED)) {
int ret;
ret = elevator_init_mq(q);
if (ret)
return ERR_PTR(ret);
}
return q;
err_hctxs:
kfree(q->queue_hw_ctx);
err_sys_init:
blk_mq_sysfs_deinit(q);
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;
blk_mq_del_queue_tag_set(q);
blk_mq_exit_hw_queues(q, set, set->nr_hw_queues);
}
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;
}
static int blk_mq_update_queue_map(struct blk_mq_tag_set *set)
{
if (set->ops->map_queues) {
int i;
/*
* transport .map_queues is usually done in the following
* way:
*
* for (queue = 0; queue < set->nr_hw_queues; queue++) {
* mask = get_cpu_mask(queue)
* for_each_cpu(cpu, mask)
* set->map[x].mq_map[cpu] = queue;
* }
*
* When we need to remap, the table has to be cleared for
* killing stale mapping since one CPU may not be mapped
* to any hw queue.
*/
for (i = 0; i < set->nr_maps; i++)
blk_mq_clear_mq_map(&set->map[i]);
return set->ops->map_queues(set);
} else {
BUG_ON(set->nr_maps > 1);
return blk_mq_map_queues(&set->map[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 it's 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 i, 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->ops->get_budget ^ !set->ops->put_budget)
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 (!set->nr_maps)
set->nr_maps = 1;
else if (set->nr_maps > HCTX_MAX_TYPES)
return -EINVAL;
/*
* 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 we just have
* a single map
*/
if (set->nr_maps == 1 && set->nr_hw_queues > nr_cpu_ids)
set->nr_hw_queues = nr_cpu_ids;
set->tags = kcalloc_node(nr_hw_queues(set), sizeof(struct blk_mq_tags *),
GFP_KERNEL, set->numa_node);
if (!set->tags)
return -ENOMEM;
ret = -ENOMEM;
for (i = 0; i < set->nr_maps; i++) {
set->map[i].mq_map = kcalloc_node(nr_cpu_ids,
sizeof(struct blk_mq_queue_map),
GFP_KERNEL, set->numa_node);
if (!set->map[i].mq_map)
goto out_free_mq_map;
set->map[i].nr_queues = set->nr_hw_queues;
}
ret = blk_mq_update_queue_map(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:
for (i = 0; i < set->nr_maps; i++) {
kfree(set->map[i].mq_map);
set->map[i].mq_map = NULL;
}
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, j;
for (i = 0; i < nr_hw_queues(set); i++)
blk_mq_free_map_and_requests(set, i);
for (j = 0; j < set->nr_maps; j++) {
kfree(set->map[j].mq_map);
set->map[j].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, nr,
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_unquiesce_queue(q);
blk_mq_unfreeze_queue(q);
return ret;
}
/*
* request_queue and elevator_type pair.
* It is just used by __blk_mq_update_nr_hw_queues to cache
* the elevator_type associated with a request_queue.
*/
struct blk_mq_qe_pair {
struct list_head node;
struct request_queue *q;
struct elevator_type *type;
};
/*
* Cache the elevator_type in qe pair list and switch the
* io scheduler to 'none'
*/
static bool blk_mq_elv_switch_none(struct list_head *head,
struct request_queue *q)
{
struct blk_mq_qe_pair *qe;
if (!q->elevator)
return true;
qe = kmalloc(sizeof(*qe), GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY);
if (!qe)
return false;
INIT_LIST_HEAD(&qe->node);
qe->q = q;
qe->type = q->elevator->type;
list_add(&qe->node, head);
mutex_lock(&q->sysfs_lock);
/*
* After elevator_switch_mq, the previous elevator_queue will be
* released by elevator_release. The reference of the io scheduler
* module get by elevator_get will also be put. So we need to get
* a reference of the io scheduler module here to prevent it to be
* removed.
*/
__module_get(qe->type->elevator_owner);
elevator_switch_mq(q, NULL);
mutex_unlock(&q->sysfs_lock);
return true;
}
static void blk_mq_elv_switch_back(struct list_head *head,
struct request_queue *q)
{
struct blk_mq_qe_pair *qe;
struct elevator_type *t = NULL;
list_for_each_entry(qe, head, node)
if (qe->q == q) {
t = qe->type;
break;
}
if (!t)
return;
list_del(&qe->node);
kfree(qe);
mutex_lock(&q->sysfs_lock);
elevator_switch_mq(q, t);
mutex_unlock(&q->sysfs_lock);
}
static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set,
int nr_hw_queues)
{
struct request_queue *q;
LIST_HEAD(head);
int prev_nr_hw_queues;
lockdep_assert_held(&set->tag_list_lock);
if (set->nr_maps == 1 && 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);
/*
* Sync with blk_mq_queue_tag_busy_iter.
*/
synchronize_rcu();
/*
* Switch IO scheduler to 'none', cleaning up the data associated
* with the previous scheduler. We will switch back once we are done
* updating the new sw to hw queue mappings.
*/
list_for_each_entry(q, &set->tag_list, tag_set_list)
if (!blk_mq_elv_switch_none(&head, q))
goto switch_back;
list_for_each_entry(q, &set->tag_list, tag_set_list) {
blk_mq_debugfs_unregister_hctxs(q);
blk_mq_sysfs_unregister(q);
}
prev_nr_hw_queues = set->nr_hw_queues;
set->nr_hw_queues = nr_hw_queues;
blk_mq_update_queue_map(set);
fallback:
list_for_each_entry(q, &set->tag_list, tag_set_list) {
blk_mq_realloc_hw_ctxs(set, q);
if (q->nr_hw_queues != set->nr_hw_queues) {
pr_warn("Increasing nr_hw_queues to %d fails, fallback to %d\n",
nr_hw_queues, prev_nr_hw_queues);
set->nr_hw_queues = prev_nr_hw_queues;
blk_mq_map_queues(&set->map[0]);
goto fallback;
}
blk_mq_map_swqueue(q);
}
list_for_each_entry(q, &set->tag_list, tag_set_list) {
blk_mq_sysfs_register(q);
blk_mq_debugfs_register_hctxs(q);
}
switch_back:
list_for_each_entry(q, &set->tag_list, tag_set_list)
blk_mq_elv_switch_back(&head, q);
list_for_each_entry(q, &set->tag_list, tag_set_list)
blk_mq_unfreeze_queue(q);
}
void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues)
{
mutex_lock(&set->tag_list_lock);
__blk_mq_update_nr_hw_queues(set, nr_hw_queues);
mutex_unlock(&set->tag_list_lock);
}
EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues);
/* Enable polling stats and return whether they were already enabled. */
static bool blk_poll_stats_enable(struct request_queue *q)
{
if (test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) ||
blk_queue_flag_test_and_set(QUEUE_FLAG_POLL_STATS, q))
return true;
blk_stat_add_callback(q, q->poll_cb);
return false;
}
static void blk_mq_poll_stats_start(struct request_queue *q)
{
/*
* We don't arm the callback if polling stats are not enabled or the
* callback is already active.
*/
if (!test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) ||
blk_stat_is_active(q->poll_cb))
return;
blk_stat_activate_msecs(q->poll_cb, 100);
}
static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb)
{
struct request_queue *q = cb->data;
int bucket;
for (bucket = 0; bucket < BLK_MQ_POLL_STATS_BKTS; bucket++) {
if (cb->stat[bucket].nr_samples)
q->poll_stat[bucket] = cb->stat[bucket];
}
}
static unsigned long blk_mq_poll_nsecs(struct request_queue *q,
struct blk_mq_hw_ctx *hctx,
struct request *rq)
{
unsigned long ret = 0;
int bucket;
/*
* If stats collection isn't on, don't sleep but turn it on for
* future users
*/
if (!blk_poll_stats_enable(q))
return 0;
/*
* 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. We do use the stats for the relevant IO size
* if available which does lead to better estimates.
*/
bucket = blk_mq_poll_stats_bkt(rq);
if (bucket < 0)
return ret;
if (q->poll_stat[bucket].nr_samples)
ret = (q->poll_stat[bucket].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 (rq->rq_flags & RQF_MQ_POLL_SLEPT)
return false;
/*
* If we get here, hybrid polling is enabled. Hence poll_nsec can be:
*
* 0: use half of prev avg
* >0: use this specific value
*/
if (q->poll_nsec > 0)
nsecs = q->poll_nsec;
else
nsecs = blk_mq_poll_nsecs(q, hctx, rq);
if (!nsecs)
return false;
rq->rq_flags |= RQF_MQ_POLL_SLEPT;
/*
* 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 (blk_mq_rq_state(rq) == MQ_RQ_COMPLETE)
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_hybrid(struct request_queue *q,
struct blk_mq_hw_ctx *hctx, blk_qc_t cookie)
{
struct request *rq;
if (q->poll_nsec == -1)
return false;
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));
/*
* With scheduling, if the request has completed, we'll
* get a NULL return here, as we clear the sched tag when
* that happens. The request still remains valid, like always,
* so we should be safe with just the NULL check.
*/
if (!rq)
return false;
}
return blk_mq_poll_hybrid_sleep(q, hctx, rq);
}
static int blk_mq_poll(struct request_queue *q, blk_qc_t cookie, bool spin)
{
struct blk_mq_hw_ctx *hctx;
long state;
if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
return 0;
hctx = q->queue_hw_ctx[blk_qc_t_to_queue_num(cookie)];
/*
* 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(q, hctx, cookie))
return 1;
hctx->poll_considered++;
state = current->state;
do {
int ret;
hctx->poll_invoked++;
ret = q->mq_ops->poll(hctx);
if (ret > 0) {
hctx->poll_success++;
__set_current_state(TASK_RUNNING);
return ret;
}
if (signal_pending_state(state, current))
__set_current_state(TASK_RUNNING);
if (current->state == TASK_RUNNING)
return 1;
if (ret < 0 || !spin)
break;
cpu_relax();
} while (!need_resched());
__set_current_state(TASK_RUNNING);
return 0;
}
unsigned int blk_mq_rq_cpu(struct request *rq)
{
return rq->mq_ctx->cpu;
}
EXPORT_SYMBOL(blk_mq_rq_cpu);
static int __init blk_mq_init(void)
{
cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD, "block/mq:dead", NULL,
blk_mq_hctx_notify_dead);
return 0;
}
subsys_initcall(blk_mq_init);
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