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cos / third_party / kernel / 5384c5015506de785504eb25ef668d31431786e5 / . / block / blk-mq.c
blob: 100fb0c3114f84f5e2ebc86b4bbe949d848daba3 [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0
/*
* 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/blk-integrity.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/interrupt.h>
#include <linux/llist.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 <linux/blk-crypto.h>
#include <linux/part_stat.h>
#include <trace/events/block.h>
#include <linux/blk-mq.h>
#include <linux/t10-pi.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"
#include "blk-ioprio.h"
static DEFINE_PER_CPU(struct llist_head, blk_cpu_done);
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, sectors, bucket;
ddir = rq_data_dir(rq);
sectors = blk_rq_stats_sectors(rq);
bucket = ddir + 2 * ilog2(sectors);
if (bucket < 0)
return -1;
else if (bucket >= BLK_MQ_POLL_STATS_BKTS)
return ddir + BLK_MQ_POLL_STATS_BKTS - 2;
return bucket;
}
#define BLK_QC_T_SHIFT 16
#define BLK_QC_T_INTERNAL (1U << 31)
static inline struct blk_mq_hw_ctx *blk_qc_to_hctx(struct request_queue *q,
blk_qc_t qc)
{
return xa_load(&q->hctx_table,
(qc & ~BLK_QC_T_INTERNAL) >> BLK_QC_T_SHIFT);
}
static inline struct request *blk_qc_to_rq(struct blk_mq_hw_ctx *hctx,
blk_qc_t qc)
{
unsigned int tag = qc & ((1U << BLK_QC_T_SHIFT) - 1);
if (qc & BLK_QC_T_INTERNAL)
return blk_mq_tag_to_rq(hctx->sched_tags, tag);
return blk_mq_tag_to_rq(hctx->tags, tag);
}
static inline blk_qc_t blk_rq_to_qc(struct request *rq)
{
return (rq->mq_hctx->queue_num << BLK_QC_T_SHIFT) |
(rq->tag != -1 ?
rq->tag : (rq->internal_tag | BLK_QC_T_INTERNAL));
}
/*
* Check if any of the ctx, dispatch list or elevator
* 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 block_device *part;
unsigned int inflight[2];
};
static bool blk_mq_check_inflight(struct request *rq, void *priv)
{
struct mq_inflight *mi = priv;
if (rq->part && blk_do_io_stat(rq) &&
(!mi->part->bd_partno || rq->part == mi->part) &&
blk_mq_rq_state(rq) == MQ_RQ_IN_FLIGHT)
mi->inflight[rq_data_dir(rq)]++;
return true;
}
unsigned int blk_mq_in_flight(struct request_queue *q,
struct block_device *part)
{
struct mq_inflight mi = { .part = part };
blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight, &mi);
return mi.inflight[0] + mi.inflight[1];
}
void blk_mq_in_flight_rw(struct request_queue *q, struct block_device *part,
unsigned int inflight[2])
{
struct mq_inflight mi = { .part = part };
blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight, &mi);
inflight[0] = mi.inflight[0];
inflight[1] = mi.inflight[1];
}
void blk_freeze_queue_start(struct request_queue *q)
{
mutex_lock(&q->mq_freeze_lock);
if (++q->mq_freeze_depth == 1) {
percpu_ref_kill(&q->q_usage_counter);
mutex_unlock(&q->mq_freeze_lock);
if (queue_is_mq(q))
blk_mq_run_hw_queues(q, false);
} else {
mutex_unlock(&q->mq_freeze_lock);
}
}
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, bool force_atomic)
{
mutex_lock(&q->mq_freeze_lock);
if (force_atomic)
q->q_usage_counter.data->force_atomic = true;
q->mq_freeze_depth--;
WARN_ON_ONCE(q->mq_freeze_depth < 0);
if (!q->mq_freeze_depth) {
percpu_ref_resurrect(&q->q_usage_counter);
wake_up_all(&q->mq_freeze_wq);
}
mutex_unlock(&q->mq_freeze_lock);
}
void blk_mq_unfreeze_queue(struct request_queue *q)
{
__blk_mq_unfreeze_queue(q, false);
}
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)
{
unsigned long flags;
spin_lock_irqsave(&q->queue_lock, flags);
if (!q->quiesce_depth++)
blk_queue_flag_set(QUEUE_FLAG_QUIESCED, q);
spin_unlock_irqrestore(&q->queue_lock, flags);
}
EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait);
/**
* blk_mq_wait_quiesce_done() - wait until in-progress quiesce is done
* @q: request queue.
*
* Note: it is driver's responsibility for making sure that quiesce has
* been started.
*/
void blk_mq_wait_quiesce_done(struct request_queue *q)
{
if (blk_queue_has_srcu(q))
synchronize_srcu(q->srcu);
else
synchronize_rcu();
}
EXPORT_SYMBOL_GPL(blk_mq_wait_quiesce_done);
/**
* 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)
{
blk_mq_quiesce_queue_nowait(q);
blk_mq_wait_quiesce_done(q);
}
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)
{
unsigned long flags;
bool run_queue = false;
spin_lock_irqsave(&q->queue_lock, flags);
if (WARN_ON_ONCE(q->quiesce_depth <= 0)) {
;
} else if (!--q->quiesce_depth) {
blk_queue_flag_clear(QUEUE_FLAG_QUIESCED, q);
run_queue = true;
}
spin_unlock_irqrestore(&q->queue_lock, flags);
/* dispatch requests which are inserted during quiescing */
if (run_queue)
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 long i;
queue_for_each_hw_ctx(q, hctx, i)
if (blk_mq_hw_queue_mapped(hctx))
blk_mq_tag_wakeup_all(hctx->tags, true);
}
void blk_rq_init(struct request_queue *q, struct request *rq)
{
memset(rq, 0, sizeof(*rq));
INIT_LIST_HEAD(&rq->queuelist);
rq->q = q;
rq->__sector = (sector_t) -1;
INIT_HLIST_NODE(&rq->hash);
RB_CLEAR_NODE(&rq->rb_node);
rq->tag = BLK_MQ_NO_TAG;
rq->internal_tag = BLK_MQ_NO_TAG;
rq->start_time_ns = ktime_get_ns();
rq->part = NULL;
blk_crypto_rq_set_defaults(rq);
}
EXPORT_SYMBOL(blk_rq_init);
static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,
struct blk_mq_tags *tags, unsigned int tag, u64 alloc_time_ns)
{
struct blk_mq_ctx *ctx = data->ctx;
struct blk_mq_hw_ctx *hctx = data->hctx;
struct request_queue *q = data->q;
struct request *rq = tags->static_rqs[tag];
rq->q = q;
rq->mq_ctx = ctx;
rq->mq_hctx = hctx;
rq->cmd_flags = data->cmd_flags;
if (data->flags & BLK_MQ_REQ_PM)
data->rq_flags |= RQF_PM;
if (blk_queue_io_stat(q))
data->rq_flags |= RQF_IO_STAT;
rq->rq_flags = data->rq_flags;
if (!(data->rq_flags & RQF_ELV)) {
rq->tag = tag;
rq->internal_tag = BLK_MQ_NO_TAG;
} else {
rq->tag = BLK_MQ_NO_TAG;
rq->internal_tag = tag;
}
rq->timeout = 0;
if (blk_mq_need_time_stamp(rq))
rq->start_time_ns = ktime_get_ns();
else
rq->start_time_ns = 0;
rq->part = NULL;
#ifdef CONFIG_BLK_RQ_ALLOC_TIME
rq->alloc_time_ns = alloc_time_ns;
#endif
rq->io_start_time_ns = 0;
rq->stats_sectors = 0;
rq->nr_phys_segments = 0;
#if defined(CONFIG_BLK_DEV_INTEGRITY)
rq->nr_integrity_segments = 0;
#endif
rq->end_io = NULL;
rq->end_io_data = NULL;
blk_crypto_rq_set_defaults(rq);
INIT_LIST_HEAD(&rq->queuelist);
/* tag was already set */
WRITE_ONCE(rq->deadline, 0);
req_ref_set(rq, 1);
if (rq->rq_flags & RQF_ELV) {
struct elevator_queue *e = data->q->elevator;
INIT_HLIST_NODE(&rq->hash);
RB_CLEAR_NODE(&rq->rb_node);
if (!op_is_flush(data->cmd_flags) &&
e->type->ops.prepare_request) {
e->type->ops.prepare_request(rq);
rq->rq_flags |= RQF_ELVPRIV;
}
}
return rq;
}
static inline struct request *
__blk_mq_alloc_requests_batch(struct blk_mq_alloc_data *data,
u64 alloc_time_ns)
{
unsigned int tag, tag_offset;
struct blk_mq_tags *tags;
struct request *rq;
unsigned long tag_mask;
int i, nr = 0;
tag_mask = blk_mq_get_tags(data, data->nr_tags, &tag_offset);
if (unlikely(!tag_mask))
return NULL;
tags = blk_mq_tags_from_data(data);
for (i = 0; tag_mask; i++) {
if (!(tag_mask & (1UL << i)))
continue;
tag = tag_offset + i;
prefetch(tags->static_rqs[tag]);
tag_mask &= ~(1UL << i);
rq = blk_mq_rq_ctx_init(data, tags, tag, alloc_time_ns);
rq_list_add(data->cached_rq, rq);
nr++;
}
/* caller already holds a reference, add for remainder */
percpu_ref_get_many(&data->q->q_usage_counter, nr - 1);
data->nr_tags -= nr;
return rq_list_pop(data->cached_rq);
}
static struct request *__blk_mq_alloc_requests(struct blk_mq_alloc_data *data)
{
struct request_queue *q = data->q;
u64 alloc_time_ns = 0;
struct request *rq;
unsigned int tag;
/* alloc_time includes depth and tag waits */
if (blk_queue_rq_alloc_time(q))
alloc_time_ns = ktime_get_ns();
if (data->cmd_flags & REQ_NOWAIT)
data->flags |= BLK_MQ_REQ_NOWAIT;
if (q->elevator) {
struct elevator_queue *e = q->elevator;
data->rq_flags |= RQF_ELV;
/*
* Flush/passthrough 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) &&
!blk_op_is_passthrough(data->cmd_flags) &&
e->type->ops.limit_depth &&
!(data->flags & BLK_MQ_REQ_RESERVED))
e->type->ops.limit_depth(data->cmd_flags, data);
}
retry:
data->ctx = blk_mq_get_ctx(q);
data->hctx = blk_mq_map_queue(q, data->cmd_flags, data->ctx);
if (!(data->rq_flags & RQF_ELV))
blk_mq_tag_busy(data->hctx);
if (data->flags & BLK_MQ_REQ_RESERVED)
data->rq_flags |= RQF_RESV;
/*
* Try batched alloc if we want more than 1 tag.
*/
if (data->nr_tags > 1) {
rq = __blk_mq_alloc_requests_batch(data, alloc_time_ns);
if (rq)
return rq;
data->nr_tags = 1;
}
/*
* Waiting allocations only fail because of an inactive hctx. In that
* case just retry the hctx assignment and tag allocation as CPU hotplug
* should have migrated us to an online CPU by now.
*/
tag = blk_mq_get_tag(data);
if (tag == BLK_MQ_NO_TAG) {
if (data->flags & BLK_MQ_REQ_NOWAIT)
return NULL;
/*
* Give up the CPU and sleep for a random short time to
* ensure that thread using a realtime scheduling class
* are migrated off the CPU, and thus off the hctx that
* is going away.
*/
msleep(3);
goto retry;
}
return blk_mq_rq_ctx_init(data, blk_mq_tags_from_data(data), tag,
alloc_time_ns);
}
static struct request *blk_mq_rq_cache_fill(struct request_queue *q,
struct blk_plug *plug,
blk_opf_t opf,
blk_mq_req_flags_t flags)
{
struct blk_mq_alloc_data data = {
.q = q,
.flags = flags,
.cmd_flags = opf,
.nr_tags = plug->nr_ios,
.cached_rq = &plug->cached_rq,
};
struct request *rq;
if (blk_queue_enter(q, flags))
return NULL;
plug->nr_ios = 1;
rq = __blk_mq_alloc_requests(&data);
if (unlikely(!rq))
blk_queue_exit(q);
return rq;
}
static struct request *blk_mq_alloc_cached_request(struct request_queue *q,
blk_opf_t opf,
blk_mq_req_flags_t flags)
{
struct blk_plug *plug = current->plug;
struct request *rq;
if (!plug)
return NULL;
if (rq_list_empty(plug->cached_rq)) {
if (plug->nr_ios == 1)
return NULL;
rq = blk_mq_rq_cache_fill(q, plug, opf, flags);
if (rq)
goto got_it;
return NULL;
}
rq = rq_list_peek(&plug->cached_rq);
if (!rq || rq->q != q)
return NULL;
if (blk_mq_get_hctx_type(opf) != rq->mq_hctx->type)
return NULL;
if (op_is_flush(rq->cmd_flags) != op_is_flush(opf))
return NULL;
plug->cached_rq = rq_list_next(rq);
got_it:
rq->cmd_flags = opf;
INIT_LIST_HEAD(&rq->queuelist);
return rq;
}
struct request *blk_mq_alloc_request(struct request_queue *q, blk_opf_t opf,
blk_mq_req_flags_t flags)
{
struct request *rq;
rq = blk_mq_alloc_cached_request(q, opf, flags);
if (!rq) {
struct blk_mq_alloc_data data = {
.q = q,
.flags = flags,
.cmd_flags = opf,
.nr_tags = 1,
};
int ret;
ret = blk_queue_enter(q, flags);
if (ret)
return ERR_PTR(ret);
rq = __blk_mq_alloc_requests(&data);
if (!rq)
goto out_queue_exit;
}
rq->__data_len = 0;
rq->__sector = (sector_t) -1;
rq->bio = rq->biotail = NULL;
return rq;
out_queue_exit:
blk_queue_exit(q);
return ERR_PTR(-EWOULDBLOCK);
}
EXPORT_SYMBOL(blk_mq_alloc_request);
struct request *blk_mq_alloc_request_hctx(struct request_queue *q,
blk_opf_t opf, blk_mq_req_flags_t flags, unsigned int hctx_idx)
{
struct blk_mq_alloc_data data = {
.q = q,
.flags = flags,
.cmd_flags = opf,
.nr_tags = 1,
};
u64 alloc_time_ns = 0;
struct request *rq;
unsigned int cpu;
unsigned int tag;
int ret;
/* alloc_time includes depth and tag waits */
if (blk_queue_rq_alloc_time(q))
alloc_time_ns = ktime_get_ns();
/*
* 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)) ||
WARN_ON_ONCE(!(flags & BLK_MQ_REQ_RESERVED)))
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.
*/
ret = -EXDEV;
data.hctx = xa_load(&q->hctx_table, hctx_idx);
if (!blk_mq_hw_queue_mapped(data.hctx))
goto out_queue_exit;
cpu = cpumask_first_and(data.hctx->cpumask, cpu_online_mask);
if (cpu >= nr_cpu_ids)
goto out_queue_exit;
data.ctx = __blk_mq_get_ctx(q, cpu);
if (!q->elevator)
blk_mq_tag_busy(data.hctx);
else
data.rq_flags |= RQF_ELV;
if (flags & BLK_MQ_REQ_RESERVED)
data.rq_flags |= RQF_RESV;
ret = -EWOULDBLOCK;
tag = blk_mq_get_tag(&data);
if (tag == BLK_MQ_NO_TAG)
goto out_queue_exit;
rq = blk_mq_rq_ctx_init(&data, blk_mq_tags_from_data(&data), tag,
alloc_time_ns);
rq->__data_len = 0;
rq->__sector = (sector_t) -1;
rq->bio = rq->biotail = NULL;
return rq;
out_queue_exit:
blk_queue_exit(q);
return ERR_PTR(ret);
}
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_crypto_free_request(rq);
blk_pm_mark_last_busy(rq);
rq->mq_hctx = NULL;
if (rq->rq_flags & RQF_MQ_INFLIGHT)
__blk_mq_dec_active_requests(hctx);
if (rq->tag != BLK_MQ_NO_TAG)
blk_mq_put_tag(hctx->tags, ctx, rq->tag);
if (sched_tag != BLK_MQ_NO_TAG)
blk_mq_put_tag(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;
if ((rq->rq_flags & RQF_ELVPRIV) &&
q->elevator->type->ops.finish_request)
q->elevator->type->ops.finish_request(rq);
if (unlikely(laptop_mode && !blk_rq_is_passthrough(rq)))
laptop_io_completion(q->disk->bdi);
rq_qos_done(q, rq);
WRITE_ONCE(rq->state, MQ_RQ_IDLE);
if (req_ref_put_and_test(rq))
__blk_mq_free_request(rq);
}
EXPORT_SYMBOL_GPL(blk_mq_free_request);
void blk_mq_free_plug_rqs(struct blk_plug *plug)
{
struct request *rq;
while ((rq = rq_list_pop(&plug->cached_rq)) != NULL)
blk_mq_free_request(rq);
}
void blk_dump_rq_flags(struct request *rq, char *msg)
{
printk(KERN_INFO "%s: dev %s: flags=%llx\n", msg,
rq->q->disk ? rq->q->disk->disk_name : "?",
(__force unsigned long long) rq->cmd_flags);
printk(KERN_INFO " sector %llu, nr/cnr %u/%u\n",
(unsigned long long)blk_rq_pos(rq),
blk_rq_sectors(rq), blk_rq_cur_sectors(rq));
printk(KERN_INFO " bio %p, biotail %p, len %u\n",
rq->bio, rq->biotail, blk_rq_bytes(rq));
}
EXPORT_SYMBOL(blk_dump_rq_flags);
static void req_bio_endio(struct request *rq, struct bio *bio,
unsigned int nbytes, blk_status_t error)
{
if (unlikely(error)) {
bio->bi_status = error;
} else if (req_op(rq) == REQ_OP_ZONE_APPEND) {
/*
* Partial zone append completions cannot be supported as the
* BIO fragments may end up not being written sequentially.
*/
if (bio->bi_iter.bi_size != nbytes)
bio->bi_status = BLK_STS_IOERR;
else
bio->bi_iter.bi_sector = rq->__sector;
}
bio_advance(bio, nbytes);
if (unlikely(rq->rq_flags & RQF_QUIET))
bio_set_flag(bio, BIO_QUIET);
/* don't actually finish bio if it's part of flush sequence */
if (bio->bi_iter.bi_size == 0 && !(rq->rq_flags & RQF_FLUSH_SEQ))
bio_endio(bio);
}
static void blk_account_io_completion(struct request *req, unsigned int bytes)
{
if (req->part && blk_do_io_stat(req)) {
const int sgrp = op_stat_group(req_op(req));
part_stat_lock();
part_stat_add(req->part, sectors[sgrp], bytes >> 9);
part_stat_unlock();
}
}
static void blk_print_req_error(struct request *req, blk_status_t status)
{
printk_ratelimited(KERN_ERR
"%s error, dev %s, sector %llu op 0x%x:(%s) flags 0x%x "
"phys_seg %u prio class %u\n",
blk_status_to_str(status),
req->q->disk ? req->q->disk->disk_name : "?",
blk_rq_pos(req), (__force u32)req_op(req),
blk_op_str(req_op(req)),
(__force u32)(req->cmd_flags & ~REQ_OP_MASK),
req->nr_phys_segments,
IOPRIO_PRIO_CLASS(req->ioprio));
}
/*
* Fully end IO on a request. Does not support partial completions, or
* errors.
*/
static void blk_complete_request(struct request *req)
{
const bool is_flush = (req->rq_flags & RQF_FLUSH_SEQ) != 0;
int total_bytes = blk_rq_bytes(req);
struct bio *bio = req->bio;
trace_block_rq_complete(req, BLK_STS_OK, total_bytes);
if (!bio)
return;
#ifdef CONFIG_BLK_DEV_INTEGRITY
if (blk_integrity_rq(req) && req_op(req) == REQ_OP_READ)
req->q->integrity.profile->complete_fn(req, total_bytes);
#endif
/*
* Upper layers may call blk_crypto_evict_key() anytime after the last
* bio_endio(). Therefore, the keyslot must be released before that.
*/
blk_crypto_rq_put_keyslot(req);
blk_account_io_completion(req, total_bytes);
do {
struct bio *next = bio->bi_next;
/* Completion has already been traced */
bio_clear_flag(bio, BIO_TRACE_COMPLETION);
if (req_op(req) == REQ_OP_ZONE_APPEND)
bio->bi_iter.bi_sector = req->__sector;
if (!is_flush)
bio_endio(bio);
bio = next;
} while (bio);
/*
* Reset counters so that the request stacking driver
* can find how many bytes remain in the request
* later.
*/
if (!req->end_io) {
req->bio = NULL;
req->__data_len = 0;
}
}
/**
* blk_update_request - Complete multiple bytes without completing the request
* @req: the request being processed
* @error: block status code
* @nr_bytes: number of bytes to complete for @req
*
* Description:
* Ends I/O on a number of bytes attached to @req, but doesn't complete
* the request structure even if @req doesn't have leftover.
* If @req has leftover, sets it up for the next range of segments.
*
* Passing the result of blk_rq_bytes() as @nr_bytes guarantees
* %false return from this function.
*
* Note:
* The RQF_SPECIAL_PAYLOAD flag is ignored on purpose in this function
* except in the consistency check at the end of this function.
*
* Return:
* %false - this request doesn't have any more data
* %true - this request has more data
**/
bool blk_update_request(struct request *req, blk_status_t error,
unsigned int nr_bytes)
{
int total_bytes;
trace_block_rq_complete(req, error, nr_bytes);
if (!req->bio)
return false;
#ifdef CONFIG_BLK_DEV_INTEGRITY
if (blk_integrity_rq(req) && req_op(req) == REQ_OP_READ &&
error == BLK_STS_OK)
req->q->integrity.profile->complete_fn(req, nr_bytes);
#endif
/*
* Upper layers may call blk_crypto_evict_key() anytime after the last
* bio_endio(). Therefore, the keyslot must be released before that.
*/
if (blk_crypto_rq_has_keyslot(req) && nr_bytes >= blk_rq_bytes(req))
__blk_crypto_rq_put_keyslot(req);
if (unlikely(error && !blk_rq_is_passthrough(req) &&
!(req->rq_flags & RQF_QUIET)) &&
!test_bit(GD_DEAD, &req->q->disk->state)) {
blk_print_req_error(req, error);
trace_block_rq_error(req, error, nr_bytes);
}
blk_account_io_completion(req, nr_bytes);
total_bytes = 0;
while (req->bio) {
struct bio *bio = req->bio;
unsigned bio_bytes = min(bio->bi_iter.bi_size, nr_bytes);
if (bio_bytes == bio->bi_iter.bi_size)
req->bio = bio->bi_next;
/* Completion has already been traced */
bio_clear_flag(bio, BIO_TRACE_COMPLETION);
req_bio_endio(req, bio, bio_bytes, error);
total_bytes += bio_bytes;
nr_bytes -= bio_bytes;
if (!nr_bytes)
break;
}
/*
* completely done
*/
if (!req->bio) {
/*
* Reset counters so that the request stacking driver
* can find how many bytes remain in the request
* later.
*/
req->__data_len = 0;
return false;
}
req->__data_len -= total_bytes;
/* update sector only for requests with clear definition of sector */
if (!blk_rq_is_passthrough(req))
req->__sector += total_bytes >> 9;
/* mixed attributes always follow the first bio */
if (req->rq_flags & RQF_MIXED_MERGE) {
req->cmd_flags &= ~REQ_FAILFAST_MASK;
req->cmd_flags |= req->bio->bi_opf & REQ_FAILFAST_MASK;
}
if (!(req->rq_flags & RQF_SPECIAL_PAYLOAD)) {
/*
* If total number of sectors is less than the first segment
* size, something has gone terribly wrong.
*/
if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) {
blk_dump_rq_flags(req, "request botched");
req->__data_len = blk_rq_cur_bytes(req);
}
/* recalculate the number of segments */
req->nr_phys_segments = blk_recalc_rq_segments(req);
}
return true;
}
EXPORT_SYMBOL_GPL(blk_update_request);
static void __blk_account_io_done(struct request *req, u64 now)
{
const int sgrp = op_stat_group(req_op(req));
part_stat_lock();
update_io_ticks(req->part, jiffies, true);
part_stat_inc(req->part, ios[sgrp]);
part_stat_add(req->part, nsecs[sgrp], now - req->start_time_ns);
part_stat_unlock();
}
static inline void blk_account_io_done(struct request *req, u64 now)
{
/*
* Account IO completion. flush_rq isn't accounted as a
* normal IO on queueing nor completion. Accounting the
* containing request is enough.
*/
if (blk_do_io_stat(req) && req->part &&
!(req->rq_flags & RQF_FLUSH_SEQ))
__blk_account_io_done(req, now);
}
static void __blk_account_io_start(struct request *rq)
{
/*
* All non-passthrough requests are created from a bio with one
* exception: when a flush command that is part of a flush sequence
* generated by the state machine in blk-flush.c is cloned onto the
* lower device by dm-multipath we can get here without a bio.
*/
if (rq->bio)
rq->part = rq->bio->bi_bdev;
else
rq->part = rq->q->disk->part0;
part_stat_lock();
update_io_ticks(rq->part, jiffies, false);
part_stat_unlock();
}
static inline void blk_account_io_start(struct request *req)
{
if (blk_do_io_stat(req))
__blk_account_io_start(req);
}
static inline void __blk_mq_end_request_acct(struct request *rq, u64 now)
{
if (rq->rq_flags & RQF_STATS) {
blk_mq_poll_stats_start(rq->q);
blk_stat_add(rq, now);
}
blk_mq_sched_completed_request(rq, now);
blk_account_io_done(rq, now);
}
inline void __blk_mq_end_request(struct request *rq, blk_status_t error)
{
if (blk_mq_need_time_stamp(rq))
__blk_mq_end_request_acct(rq, ktime_get_ns());
if (rq->end_io) {
rq_qos_done(rq->q, rq);
if (rq->end_io(rq, error) == RQ_END_IO_FREE)
blk_mq_free_request(rq);
} else {
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);
#define TAG_COMP_BATCH 32
static inline void blk_mq_flush_tag_batch(struct blk_mq_hw_ctx *hctx,
int *tag_array, int nr_tags)
{
struct request_queue *q = hctx->queue;
/*
* All requests should have been marked as RQF_MQ_INFLIGHT, so
* update hctx->nr_active in batch
*/
if (hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED)
__blk_mq_sub_active_requests(hctx, nr_tags);
blk_mq_put_tags(hctx->tags, tag_array, nr_tags);
percpu_ref_put_many(&q->q_usage_counter, nr_tags);
}
void blk_mq_end_request_batch(struct io_comp_batch *iob)
{
int tags[TAG_COMP_BATCH], nr_tags = 0;
struct blk_mq_hw_ctx *cur_hctx = NULL;
struct request *rq;
u64 now = 0;
if (iob->need_ts)
now = ktime_get_ns();
while ((rq = rq_list_pop(&iob->req_list)) != NULL) {
prefetch(rq->bio);
prefetch(rq->rq_next);
blk_complete_request(rq);
if (iob->need_ts)
__blk_mq_end_request_acct(rq, now);
rq_qos_done(rq->q, rq);
/*
* If end_io handler returns NONE, then it still has
* ownership of the request.
*/
if (rq->end_io && rq->end_io(rq, 0) == RQ_END_IO_NONE)
continue;
WRITE_ONCE(rq->state, MQ_RQ_IDLE);
if (!req_ref_put_and_test(rq))
continue;
blk_crypto_free_request(rq);
blk_pm_mark_last_busy(rq);
if (nr_tags == TAG_COMP_BATCH || cur_hctx != rq->mq_hctx) {
if (cur_hctx)
blk_mq_flush_tag_batch(cur_hctx, tags, nr_tags);
nr_tags = 0;
cur_hctx = rq->mq_hctx;
}
tags[nr_tags++] = rq->tag;
}
if (nr_tags)
blk_mq_flush_tag_batch(cur_hctx, tags, nr_tags);
}
EXPORT_SYMBOL_GPL(blk_mq_end_request_batch);
static void blk_complete_reqs(struct llist_head *list)
{
struct llist_node *entry = llist_reverse_order(llist_del_all(list));
struct request *rq, *next;
llist_for_each_entry_safe(rq, next, entry, ipi_list)
rq->q->mq_ops->complete(rq);
}
static __latent_entropy void blk_done_softirq(struct softirq_action *h)
{
blk_complete_reqs(this_cpu_ptr(&blk_cpu_done));
}
static int blk_softirq_cpu_dead(unsigned int cpu)
{
blk_complete_reqs(&per_cpu(blk_cpu_done, cpu));
return 0;
}
static void __blk_mq_complete_request_remote(void *data)
{
__raise_softirq_irqoff(BLOCK_SOFTIRQ);
}
static inline bool blk_mq_complete_need_ipi(struct request *rq)
{
int cpu = raw_smp_processor_id();
if (!IS_ENABLED(CONFIG_SMP) ||
!test_bit(QUEUE_FLAG_SAME_COMP, &rq->q->queue_flags))
return false;
/*
* With force threaded interrupts enabled, raising softirq from an SMP
* function call will always result in waking the ksoftirqd thread.
* This is probably worse than completing the request on a different
* cache domain.
*/
if (force_irqthreads())
return false;
/* same CPU or cache domain? Complete locally */
if (cpu == rq->mq_ctx->cpu ||
(!test_bit(QUEUE_FLAG_SAME_FORCE, &rq->q->queue_flags) &&
cpus_share_cache(cpu, rq->mq_ctx->cpu)))
return false;
/* don't try to IPI to an offline CPU */
return cpu_online(rq->mq_ctx->cpu);
}
static void blk_mq_complete_send_ipi(struct request *rq)
{
struct llist_head *list;
unsigned int cpu;
cpu = rq->mq_ctx->cpu;
list = &per_cpu(blk_cpu_done, cpu);
if (llist_add(&rq->ipi_list, list)) {
INIT_CSD(&rq->csd, __blk_mq_complete_request_remote, rq);
smp_call_function_single_async(cpu, &rq->csd);
}
}
static void blk_mq_raise_softirq(struct request *rq)
{
struct llist_head *list;
preempt_disable();
list = this_cpu_ptr(&blk_cpu_done);
if (llist_add(&rq->ipi_list, list))
raise_softirq(BLOCK_SOFTIRQ);
preempt_enable();
}
bool blk_mq_complete_request_remote(struct request *rq)
{
WRITE_ONCE(rq->state, MQ_RQ_COMPLETE);
/*
* For request which hctx has only one ctx mapping,
* or a polled request, always complete locally,
* it's pointless to redirect the completion.
*/
if (rq->mq_hctx->nr_ctx == 1 ||
rq->cmd_flags & REQ_POLLED)
return false;
if (blk_mq_complete_need_ipi(rq)) {
blk_mq_complete_send_ipi(rq);
return true;
}
if (rq->q->nr_hw_queues == 1) {
blk_mq_raise_softirq(rq);
return true;
}
return false;
}
EXPORT_SYMBOL_GPL(blk_mq_complete_request_remote);
/**
* blk_mq_complete_request - end I/O on a request
* @rq: the request being processed
*
* Description:
* Complete a request by scheduling the ->complete_rq operation.
**/
void blk_mq_complete_request(struct request *rq)
{
if (!blk_mq_complete_request_remote(rq))
rq->q->mq_ops->complete(rq);
}
EXPORT_SYMBOL(blk_mq_complete_request);
/**
* blk_mq_start_request - Start processing a request
* @rq: Pointer to request to be started
*
* Function used by device drivers to notify the block layer that a request
* is going to be processed now, so blk layer can do proper initializations
* such as starting the timeout timer.
*/
void blk_mq_start_request(struct request *rq)
{
struct request_queue *q = rq->q;
trace_block_rq_issue(rq);
if (test_bit(QUEUE_FLAG_STATS, &q->queue_flags)) {
rq->io_start_time_ns = ktime_get_ns();
rq->stats_sectors = blk_rq_sectors(rq);
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);
#ifdef CONFIG_BLK_DEV_INTEGRITY
if (blk_integrity_rq(rq) && req_op(rq) == REQ_OP_WRITE)
q->integrity.profile->prepare_fn(rq);
#endif
if (rq->bio && rq->bio->bi_opf & REQ_POLLED)
WRITE_ONCE(rq->bio->bi_cookie, blk_rq_to_qc(rq));
}
EXPORT_SYMBOL(blk_mq_start_request);
/*
* Allow 2x BLK_MAX_REQUEST_COUNT requests on plug queue for multiple
* queues. This is important for md arrays to benefit from merging
* requests.
*/
static inline unsigned short blk_plug_max_rq_count(struct blk_plug *plug)
{
if (plug->multiple_queues)
return BLK_MAX_REQUEST_COUNT * 2;
return BLK_MAX_REQUEST_COUNT;
}
static void blk_add_rq_to_plug(struct blk_plug *plug, struct request *rq)
{
struct request *last = rq_list_peek(&plug->mq_list);
if (!plug->rq_count) {
trace_block_plug(rq->q);
} else if (plug->rq_count >= blk_plug_max_rq_count(plug) ||
(!blk_queue_nomerges(rq->q) &&
blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) {
blk_mq_flush_plug_list(plug, false);
last = NULL;
trace_block_plug(rq->q);
}
if (!plug->multiple_queues && last && last->q != rq->q)
plug->multiple_queues = true;
if (!plug->has_elevator && (rq->rq_flags & RQF_ELV))
plug->has_elevator = true;
rq->rq_next = NULL;
rq_list_add(&plug->mq_list, rq);
plug->rq_count++;
}
/**
* blk_execute_rq_nowait - insert a request to I/O scheduler for execution
* @rq: request to insert
* @at_head: insert request at head or tail of queue
*
* Description:
* Insert a fully prepared request at the back of the I/O scheduler queue
* for execution. Don't wait for completion.
*
* Note:
* This function will invoke @done directly if the queue is dead.
*/
void blk_execute_rq_nowait(struct request *rq, bool at_head)
{
WARN_ON(irqs_disabled());
WARN_ON(!blk_rq_is_passthrough(rq));
blk_account_io_start(rq);
/*
* As plugging can be enabled for passthrough requests on a zoned
* device, directly accessing the plug instead of using blk_mq_plug()
* should not have any consequences.
*/
if (current->plug && !at_head)
blk_add_rq_to_plug(current->plug, rq);
else
blk_mq_sched_insert_request(rq, at_head, true, false);
}
EXPORT_SYMBOL_GPL(blk_execute_rq_nowait);
struct blk_rq_wait {
struct completion done;
blk_status_t ret;
};
static enum rq_end_io_ret blk_end_sync_rq(struct request *rq, blk_status_t ret)
{
struct blk_rq_wait *wait = rq->end_io_data;
wait->ret = ret;
complete(&wait->done);
return RQ_END_IO_NONE;
}
bool blk_rq_is_poll(struct request *rq)
{
if (!rq->mq_hctx)
return false;
if (rq->mq_hctx->type != HCTX_TYPE_POLL)
return false;
return true;
}
EXPORT_SYMBOL_GPL(blk_rq_is_poll);
static void blk_rq_poll_completion(struct request *rq, struct completion *wait)
{
do {
blk_mq_poll(rq->q, blk_rq_to_qc(rq), NULL, 0);
cond_resched();
} while (!completion_done(wait));
}
/**
* blk_execute_rq - insert a request into queue for execution
* @rq: request to insert
* @at_head: insert request at head or tail of queue
*
* Description:
* Insert a fully prepared request at the back of the I/O scheduler queue
* for execution and wait for completion.
* Return: The blk_status_t result provided to blk_mq_end_request().
*/
blk_status_t blk_execute_rq(struct request *rq, bool at_head)
{
struct blk_rq_wait wait = {
.done = COMPLETION_INITIALIZER_ONSTACK(wait.done),
};
WARN_ON(irqs_disabled());
WARN_ON(!blk_rq_is_passthrough(rq));
rq->end_io_data = &wait;
rq->end_io = blk_end_sync_rq;
blk_account_io_start(rq);
blk_mq_sched_insert_request(rq, at_head, true, false);
if (blk_rq_is_poll(rq)) {
blk_rq_poll_completion(rq, &wait.done);
} else {
/*
* Prevent hang_check timer from firing at us during very long
* I/O
*/
unsigned long hang_check = sysctl_hung_task_timeout_secs;
if (hang_check)
while (!wait_for_completion_io_timeout(&wait.done,
hang_check * (HZ/2)))
;
else
wait_for_completion_io(&wait.done);
}
return wait.ret;
}
EXPORT_SYMBOL(blk_execute_rq);
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(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;
}
}
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);
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 | RQF_DONTPREP)))
continue;
rq->rq_flags &= ~RQF_SOFTBARRIER;
list_del_init(&rq->queuelist);
/*
* If RQF_DONTPREP, rq has contained some driver specific
* data, so insert it to hctx dispatch list to avoid any
* merge.
*/
if (rq->rq_flags & RQF_DONTPREP)
blk_mq_request_bypass_insert(rq, false, false);
else
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);
}
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);
static bool blk_mq_rq_inflight(struct request *rq, void *priv)
{
/*
* If we find a request that isn't idle we know the queue is busy
* as it's checked in the iter.
* Return false to stop the iteration.
*/
if (blk_mq_request_started(rq)) {
bool *busy = priv;
*busy = true;
return false;
}
return true;
}
bool blk_mq_queue_inflight(struct request_queue *q)
{
bool busy = false;
blk_mq_queue_tag_busy_iter(q, blk_mq_rq_inflight, &busy);
return busy;
}
EXPORT_SYMBOL_GPL(blk_mq_queue_inflight);
static void blk_mq_rq_timed_out(struct request *req)
{
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);
if (ret == BLK_EH_DONE)
return;
WARN_ON_ONCE(ret != BLK_EH_RESET_TIMER);
}
blk_add_timer(req);
}
struct blk_expired_data {
bool has_timedout_rq;
unsigned long next;
unsigned long timeout_start;
};
static bool blk_mq_req_expired(struct request *rq, struct blk_expired_data *expired)
{
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(expired->timeout_start, deadline))
return true;
if (expired->next == 0)
expired->next = deadline;
else if (time_after(expired->next, deadline))
expired->next = deadline;
return false;
}
void blk_mq_put_rq_ref(struct request *rq)
{
if (is_flush_rq(rq)) {
if (rq->end_io(rq, 0) == RQ_END_IO_FREE)
blk_mq_free_request(rq);
} else if (req_ref_put_and_test(rq)) {
__blk_mq_free_request(rq);
}
}
static bool blk_mq_check_expired(struct request *rq, void *priv)
{
struct blk_expired_data *expired = priv;
/*
* blk_mq_queue_tag_busy_iter() has locked the request, so it cannot
* be reallocated underneath the timeout handler's processing, then
* the expire check is reliable. If the request is not expired, then
* it was completed and reallocated as a new request after returning
* from blk_mq_check_expired().
*/
if (blk_mq_req_expired(rq, expired)) {
expired->has_timedout_rq = true;
return false;
}
return true;
}
static bool blk_mq_handle_expired(struct request *rq, void *priv)
{
struct blk_expired_data *expired = priv;
if (blk_mq_req_expired(rq, expired))
blk_mq_rq_timed_out(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);
struct blk_expired_data expired = {
.timeout_start = jiffies,
};
struct blk_mq_hw_ctx *hctx;
unsigned long 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;
/* check if there is any timed-out request */
blk_mq_queue_tag_busy_iter(q, blk_mq_check_expired, &expired);
if (expired.has_timedout_rq) {
/*
* Before walking tags, we must ensure any submit started
* before the current time has finished. Since the submit
* uses srcu or rcu, wait for a synchronization point to
* ensure all running submits have finished
*/
blk_mq_wait_quiesce_done(q);
expired.next = 0;
blk_mq_queue_tag_busy_iter(q, blk_mq_handle_expired, &expired);
}
if (expired.next != 0) {
mod_timer(&q->timeout, expired.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];
enum hctx_type type = hctx->type;
spin_lock(&ctx->lock);
list_splice_tail_init(&ctx->rq_lists[type], 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];
enum hctx_type type = hctx->type;
spin_lock(&ctx->lock);
if (!list_empty(&ctx->rq_lists[type])) {
dispatch_data->rq = list_entry_rq(ctx->rq_lists[type].next);
list_del_init(&dispatch_data->rq->queuelist);
if (list_empty(&ctx->rq_lists[type]))
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 bool __blk_mq_alloc_driver_tag(struct request *rq)
{
struct sbitmap_queue *bt = &rq->mq_hctx->tags->bitmap_tags;
unsigned int tag_offset = rq->mq_hctx->tags->nr_reserved_tags;
int tag;
blk_mq_tag_busy(rq->mq_hctx);
if (blk_mq_tag_is_reserved(rq->mq_hctx->sched_tags, rq->internal_tag)) {
bt = &rq->mq_hctx->tags->breserved_tags;
tag_offset = 0;
} else {
if (!hctx_may_queue(rq->mq_hctx, bt))
return false;
}
tag = __sbitmap_queue_get(bt);
if (tag == BLK_MQ_NO_TAG)
return false;
rq->tag = tag + tag_offset;
return true;
}
bool __blk_mq_get_driver_tag(struct blk_mq_hw_ctx *hctx, struct request *rq)
{
if (rq->tag == BLK_MQ_NO_TAG && !__blk_mq_alloc_driver_tag(rq))
return false;
if ((hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED) &&
!(rq->rq_flags & RQF_MQ_INFLIGHT)) {
rq->rq_flags |= RQF_MQ_INFLIGHT;
__blk_mq_inc_active_requests(hctx);
}
hctx->tags->rqs[rq->tag] = rq;
return true;
}
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);
if (!list_empty(&wait->entry)) {
struct sbitmap_queue *sbq;
list_del_init(&wait->entry);
sbq = &hctx->tags->bitmap_tags;
atomic_dec(&sbq->ws_active);
}
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 sbitmap_queue *sbq;
struct wait_queue_head *wq;
wait_queue_entry_t *wait;
bool ret;
if (!(hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED) &&
!(blk_mq_is_shared_tags(hctx->flags))) {
blk_mq_sched_mark_restart_hctx(hctx);
/*
* 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;
if (blk_mq_tag_is_reserved(rq->mq_hctx->sched_tags, rq->internal_tag))
sbq = &hctx->tags->breserved_tags;
else
sbq = &hctx->tags->bitmap_tags;
wq = &bt_wait_ptr(sbq, 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;
}
atomic_inc(&sbq->ws_active);
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);
atomic_dec(&sbq->ws_active);
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;
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 */
static void blk_mq_handle_dev_resource(struct request *rq,
struct list_head *list)
{
struct request *next =
list_first_entry_or_null(list, struct request, queuelist);
/*
* If an I/O scheduler has been configured and we got a driver tag for
* the next request already, free it.
*/
if (next)
blk_mq_put_driver_tag(next);
list_add(&rq->queuelist, list);
__blk_mq_requeue_request(rq);
}
static void blk_mq_handle_zone_resource(struct request *rq,
struct list_head *zone_list)
{
/*
* If we end up here it is because we cannot dispatch a request to a
* specific zone due to LLD level zone-write locking or other zone
* related resource not being available. In this case, set the request
* aside in zone_list for retrying it later.
*/
list_add(&rq->queuelist, zone_list);
__blk_mq_requeue_request(rq);
}
enum prep_dispatch {
PREP_DISPATCH_OK,
PREP_DISPATCH_NO_TAG,
PREP_DISPATCH_NO_BUDGET,
};
static enum prep_dispatch blk_mq_prep_dispatch_rq(struct request *rq,
bool need_budget)
{
struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
int budget_token = -1;
if (need_budget) {
budget_token = blk_mq_get_dispatch_budget(rq->q);
if (budget_token < 0) {
blk_mq_put_driver_tag(rq);
return PREP_DISPATCH_NO_BUDGET;
}
blk_mq_set_rq_budget_token(rq, budget_token);
}
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)) {
/*
* All budgets not got from this function will be put
* together during handling partial dispatch
*/
if (need_budget)
blk_mq_put_dispatch_budget(rq->q, budget_token);
return PREP_DISPATCH_NO_TAG;
}
}
return PREP_DISPATCH_OK;
}
/* release all allocated budgets before calling to blk_mq_dispatch_rq_list */
static void blk_mq_release_budgets(struct request_queue *q,
struct list_head *list)
{
struct request *rq;
list_for_each_entry(rq, list, queuelist) {
int budget_token = blk_mq_get_rq_budget_token(rq);
if (budget_token >= 0)
blk_mq_put_dispatch_budget(q, budget_token);
}
}
/*
* Returns true if we did some work AND can potentially do more.
*/
bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx *hctx, struct list_head *list,
unsigned int nr_budgets)
{
enum prep_dispatch prep;
struct request_queue *q = hctx->queue;
struct request *rq, *nxt;
int errors, queued;
blk_status_t ret = BLK_STS_OK;
LIST_HEAD(zone_list);
bool needs_resource = false;
if (list_empty(list))
return false;
/*
* 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);
WARN_ON_ONCE(hctx != rq->mq_hctx);
prep = blk_mq_prep_dispatch_rq(rq, !nr_budgets);
if (prep != PREP_DISPATCH_OK)
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);
}
/*
* once the request is queued to lld, no need to cover the
* budget any more
*/
if (nr_budgets)
nr_budgets--;
ret = q->mq_ops->queue_rq(hctx, &bd);
switch (ret) {
case BLK_STS_OK:
queued++;
break;
case BLK_STS_RESOURCE:
needs_resource = true;
fallthrough;
case BLK_STS_DEV_RESOURCE:
blk_mq_handle_dev_resource(rq, list);
goto out;
case BLK_STS_ZONE_RESOURCE:
/*
* Move the request to zone_list and keep going through
* the dispatch list to find more requests the drive can
* accept.
*/
blk_mq_handle_zone_resource(rq, &zone_list);
needs_resource = true;
break;
default:
errors++;
blk_mq_end_request(rq, ret);
}
} while (!list_empty(list));
out:
if (!list_empty(&zone_list))
list_splice_tail_init(&zone_list, list);
/* If we didn't flush the entire list, we could have told the driver
* there was more coming, but that turned out to be a lie.
*/
if ((!list_empty(list) || errors || needs_resource ||
ret == BLK_STS_DEV_RESOURCE) && q->mq_ops->commit_rqs && queued)
q->mq_ops->commit_rqs(hctx);
/*
* 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;
/* For non-shared tags, the RESTART check will suffice */
bool no_tag = prep == PREP_DISPATCH_NO_TAG &&
((hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED) ||
blk_mq_is_shared_tags(hctx->flags));
if (nr_budgets)
blk_mq_release_budgets(q, list);
spin_lock(&hctx->lock);
list_splice_tail_init(list, &hctx->dispatch);
spin_unlock(&hctx->lock);
/*
* Order adding requests to hctx->dispatch and checking
* SCHED_RESTART flag. The pair of this smp_mb() is the one
* in blk_mq_sched_restart(). Avoid restart code path to
* miss the new added requests to hctx->dispatch, meantime
* SCHED_RESTART is observed here.
*/
smp_mb();
/*
* 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. We'll do
* similar if we couldn't get budget or couldn't lock a zone
* and SCHED_RESTART is set.
*/
needs_restart = blk_mq_sched_needs_restart(hctx);
if (prep == PREP_DISPATCH_NO_BUDGET)
needs_resource = true;
if (!needs_restart ||
(no_tag && list_empty_careful(&hctx->dispatch_wait.entry)))
blk_mq_run_hw_queue(hctx, true);
else if (needs_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);
return (queued + errors) != 0;
}
/**
* __blk_mq_run_hw_queue - Run a hardware queue.
* @hctx: Pointer to the hardware queue to run.
*
* Send pending requests to the hardware.
*/
static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
{
/*
* We can't run the queue inline with ints disabled. Ensure that
* we catch bad users of this early.
*/
WARN_ON_ONCE(in_interrupt());
blk_mq_run_dispatch_ops(hctx->queue,
blk_mq_sched_dispatch_requests(hctx));
}
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;
}
/**
* __blk_mq_delay_run_hw_queue - Run (or schedule to run) a hardware queue.
* @hctx: Pointer to the hardware queue to run.
* @async: If we want to run the queue asynchronously.
* @msecs: Milliseconds of delay to wait before running the queue.
*
* If !@async, try to run the queue now. Else, run the queue asynchronously and
* with a delay of @msecs.
*/
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)) {
if (cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask)) {
__blk_mq_run_hw_queue(hctx);
return;
}
}
kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx), &hctx->run_work,
msecs_to_jiffies(msecs));
}
/**
* blk_mq_delay_run_hw_queue - Run a hardware queue asynchronously.
* @hctx: Pointer to the hardware queue to run.
* @msecs: Milliseconds of delay to wait before running the queue.
*
* Run a hardware queue asynchronously with a delay of @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);
/**
* blk_mq_run_hw_queue - Start to run a hardware queue.
* @hctx: Pointer to the hardware queue to run.
* @async: If we want to run the queue asynchronously.
*
* Check if the request queue is not in a quiesced state and if there are
* pending requests to be sent. If this is true, run the queue to send requests
* to hardware.
*/
void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
{
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.
*/
__blk_mq_run_dispatch_ops(hctx->queue, false,
need_run = !blk_queue_quiesced(hctx->queue) &&
blk_mq_hctx_has_pending(hctx));
if (need_run)
__blk_mq_delay_run_hw_queue(hctx, async, 0);
}
EXPORT_SYMBOL(blk_mq_run_hw_queue);
/*
* Return prefered queue to dispatch from (if any) for non-mq aware IO
* scheduler.
*/
static struct blk_mq_hw_ctx *blk_mq_get_sq_hctx(struct request_queue *q)
{
struct blk_mq_ctx *ctx = blk_mq_get_ctx(q);
/*
* If the IO scheduler does not respect hardware queues when
* dispatching, we just don't bother with multiple HW queues and
* dispatch from hctx for the current CPU since running multiple queues
* just causes lock contention inside the scheduler and pointless cache
* bouncing.
*/
struct blk_mq_hw_ctx *hctx = ctx->hctxs[HCTX_TYPE_DEFAULT];
if (!blk_mq_hctx_stopped(hctx))
return hctx;
return NULL;
}
/**
* blk_mq_run_hw_queues - Run all hardware queues in a request queue.
* @q: Pointer to the request queue to run.
* @async: If we want to run the queue asynchronously.
*/
void blk_mq_run_hw_queues(struct request_queue *q, bool async)
{
struct blk_mq_hw_ctx *hctx, *sq_hctx;
unsigned long i;
sq_hctx = NULL;
if (blk_queue_sq_sched(q))
sq_hctx = blk_mq_get_sq_hctx(q);
queue_for_each_hw_ctx(q, hctx, i) {
if (blk_mq_hctx_stopped(hctx))
continue;
/*
* Dispatch from this hctx either if there's no hctx preferred
* by IO scheduler or if it has requests that bypass the
* scheduler.
*/
if (!sq_hctx || sq_hctx == hctx ||
!list_empty_careful(&hctx->dispatch))
blk_mq_run_hw_queue(hctx, async);
}
}
EXPORT_SYMBOL(blk_mq_run_hw_queues);
/**
* blk_mq_delay_run_hw_queues - Run all hardware queues asynchronously.
* @q: Pointer to the request queue to run.
* @msecs: Milliseconds of delay to wait before running the queues.
*/
void blk_mq_delay_run_hw_queues(struct request_queue *q, unsigned long msecs)
{
struct blk_mq_hw_ctx *hctx, *sq_hctx;
unsigned long i;
sq_hctx = NULL;
if (blk_queue_sq_sched(q))
sq_hctx = blk_mq_get_sq_hctx(q);
queue_for_each_hw_ctx(q, hctx, i) {
if (blk_mq_hctx_stopped(hctx))
continue;
/*
* If there is already a run_work pending, leave the
* pending delay untouched. Otherwise, a hctx can stall
* if another hctx is re-delaying the other's work
* before the work executes.
*/
if (delayed_work_pending(&hctx->run_work))
continue;
/*
* Dispatch from this hctx either if there's no hctx preferred
* by IO scheduler or if it has requests that bypass the
* scheduler.
*/
if (!sq_hctx || sq_hctx == hctx ||
!list_empty_careful(&hctx->dispatch))
blk_mq_delay_run_hw_queue(hctx, msecs);
}
}
EXPORT_SYMBOL(blk_mq_delay_run_hw_queues);
/*
* 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;
unsigned long 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;
unsigned long 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;
unsigned long 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 (blk_mq_hctx_stopped(hctx))
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;
enum hctx_type type = hctx->type;
lockdep_assert_held(&ctx->lock);
trace_block_rq_insert(rq);
if (at_head)
list_add(&rq->queuelist, &ctx->rq_lists[type]);
else
list_add_tail(&rq->queuelist, &ctx->rq_lists[type]);
}
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);
}
/**
* blk_mq_request_bypass_insert - Insert a request at dispatch list.
* @rq: Pointer to request to be inserted.
* @at_head: true if the request should be inserted at the head of the list.
* @run_queue: If we should run the hardware queue after inserting the request.
*
* 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 at_head,
bool run_queue)
{
struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
spin_lock(&hctx->lock);
if (at_head)
list_add(&rq->queuelist, &hctx->dispatch);
else
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;
enum hctx_type type = hctx->type;
/*
* 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(rq);
}
spin_lock(&ctx->lock);
list_splice_tail_init(list, &ctx->rq_lists[type]);
blk_mq_hctx_mark_pending(hctx, ctx);
spin_unlock(&ctx->lock);
}
static void blk_mq_commit_rqs(struct blk_mq_hw_ctx *hctx, int *queued,
bool from_schedule)
{
if (hctx->queue->mq_ops->commit_rqs) {
trace_block_unplug(hctx->queue, *queued, !from_schedule);
hctx->queue->mq_ops->commit_rqs(hctx);
}
*queued = 0;
}
static void blk_mq_bio_to_request(struct request *rq, struct bio *bio,
unsigned int nr_segs)
{
int err;
if (bio->bi_opf & REQ_RAHEAD)
rq->cmd_flags |= REQ_FAILFAST_MASK;
rq->__sector = bio->bi_iter.bi_sector;
blk_rq_bio_prep(rq, bio, nr_segs);
/* This can't fail, since GFP_NOIO includes __GFP_DIRECT_RECLAIM. */
err = blk_crypto_rq_bio_prep(rq, bio, GFP_NOIO);
WARN_ON_ONCE(err);
blk_account_io_start(rq);
}
static blk_status_t __blk_mq_issue_directly(struct blk_mq_hw_ctx *hctx,
struct request *rq, bool last)
{
struct request_queue *q = rq->q;
struct blk_mq_queue_data bd = {
.rq = rq,
.last = last,
};
blk_status_t ret;
/*
* 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);
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);
break;
}
return ret;
}
static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
struct request *rq,
bool bypass_insert, bool last)
{
struct request_queue *q = rq->q;
bool run_queue = true;
int budget_token;
/*
* 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 ((rq->rq_flags & RQF_ELV) && !bypass_insert)
goto insert;
budget_token = blk_mq_get_dispatch_budget(q);
if (budget_token < 0)
goto insert;
blk_mq_set_rq_budget_token(rq, budget_token);
if (!blk_mq_get_driver_tag(rq)) {
blk_mq_put_dispatch_budget(q, budget_token);
goto insert;
}
return __blk_mq_issue_directly(hctx, rq, last);
insert:
if (bypass_insert)
return BLK_STS_RESOURCE;
blk_mq_sched_insert_request(rq, false, run_queue, false);
return BLK_STS_OK;
}
/**
* blk_mq_try_issue_directly - Try to send a request directly to device driver.
* @hctx: Pointer of the associated hardware queue.
* @rq: Pointer to request to be sent.
*
* If the device has enough resources to accept a new request now, send the
* request directly to device driver. Else, insert at hctx->dispatch queue, so
* we can try send it another time in the future. Requests inserted at this
* queue have higher priority.
*/
static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx,
struct request *rq)
{
blk_status_t ret =
__blk_mq_try_issue_directly(hctx, rq, false, true);
if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE)
blk_mq_request_bypass_insert(rq, false, true);
else if (ret != BLK_STS_OK)
blk_mq_end_request(rq, ret);
}
static blk_status_t blk_mq_request_issue_directly(struct request *rq, bool last)
{
return __blk_mq_try_issue_directly(rq->mq_hctx, rq, true, last);
}
static void blk_mq_plug_issue_direct(struct blk_plug *plug, bool from_schedule)
{
struct blk_mq_hw_ctx *hctx = NULL;
struct request *rq;
int queued = 0;
int errors = 0;
while ((rq = rq_list_pop(&plug->mq_list))) {
bool last = rq_list_empty(plug->mq_list);
blk_status_t ret;
if (hctx != rq->mq_hctx) {
if (hctx)
blk_mq_commit_rqs(hctx, &queued, from_schedule);
hctx = rq->mq_hctx;
}
ret = blk_mq_request_issue_directly(rq, last);
switch (ret) {
case BLK_STS_OK:
queued++;
break;
case BLK_STS_RESOURCE:
case BLK_STS_DEV_RESOURCE:
blk_mq_request_bypass_insert(rq, false, true);
blk_mq_commit_rqs(hctx, &queued, from_schedule);
return;
default:
blk_mq_end_request(rq, ret);
errors++;
break;
}
}
/*
* If we didn't flush the entire list, we could have told the driver
* there was more coming, but that turned out to be a lie.
*/
if (errors)
blk_mq_commit_rqs(hctx, &queued, from_schedule);
}
static void __blk_mq_flush_plug_list(struct request_queue *q,
struct blk_plug *plug)
{
if (blk_queue_quiesced(q))
return;
q->mq_ops->queue_rqs(&plug->mq_list);
}
static void blk_mq_dispatch_plug_list(struct blk_plug *plug, bool from_sched)
{
struct blk_mq_hw_ctx *this_hctx = NULL;
struct blk_mq_ctx *this_ctx = NULL;
struct request *requeue_list = NULL;
struct request **requeue_lastp = &requeue_list;
unsigned int depth = 0;
LIST_HEAD(list);
do {
struct request *rq = rq_list_pop(&plug->mq_list);
if (!this_hctx) {
this_hctx = rq->mq_hctx;
this_ctx = rq->mq_ctx;
} else if (this_hctx != rq->mq_hctx || this_ctx != rq->mq_ctx) {
rq_list_add_tail(&requeue_lastp, rq);
continue;
}
list_add(&rq->queuelist, &list);
depth++;
} while (!rq_list_empty(plug->mq_list));
plug->mq_list = requeue_list;
trace_block_unplug(this_hctx->queue, depth, !from_sched);
blk_mq_sched_insert_requests(this_hctx, this_ctx, &list, from_sched);
}
void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule)
{
struct request *rq;
/*
* We may have been called recursively midway through handling
* plug->mq_list via a schedule() in the driver's queue_rq() callback.
* To avoid mq_list changing under our feet, clear rq_count early and
* bail out specifically if rq_count is 0 rather than checking
* whether the mq_list is empty.
*/
if (plug->rq_count == 0)
return;
plug->rq_count = 0;
if (!plug->multiple_queues && !plug->has_elevator && !from_schedule) {
struct request_queue *q;
rq = rq_list_peek(&plug->mq_list);
q = rq->q;
/*
* Peek first request and see if we have a ->queue_rqs() hook.
* If we do, we can dispatch the whole plug list in one go. We
* already know at this point that all requests belong to the
* same queue, caller must ensure that's the case.
*
* Since we pass off the full list to the driver at this point,
* we do not increment the active request count for the queue.
* Bypass shared tags for now because of that.
*/
if (q->mq_ops->queue_rqs &&
!(rq->mq_hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED)) {
blk_mq_run_dispatch_ops(q,
__blk_mq_flush_plug_list(q, plug));
if (rq_list_empty(plug->mq_list))
return;
}
blk_mq_run_dispatch_ops(q,
blk_mq_plug_issue_direct(plug, false));
if (rq_list_empty(plug->mq_list))
return;
}
do {
blk_mq_dispatch_plug_list(plug, from_schedule);
} while (!rq_list_empty(plug->mq_list));
}
void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx *hctx,
struct list_head *list)
{
int queued = 0;
int errors = 0;
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, list_empty(list));
if (ret != BLK_STS_OK) {
errors++;
if (ret == BLK_STS_RESOURCE ||
ret == BLK_STS_DEV_RESOURCE) {
blk_mq_request_bypass_insert(rq, false,
list_empty(list));
break;
}
blk_mq_end_request(rq, ret);
} else
queued++;
}
/*
* If we didn't flush the entire list, we could have told
* the driver there was more coming, but that turned out to
* be a lie.
*/
if ((!list_empty(list) || errors) &&
hctx->queue->mq_ops->commit_rqs && queued)
hctx->queue->mq_ops->commit_rqs(hctx);
}
static bool blk_mq_attempt_bio_merge(struct request_queue *q,
struct bio *bio, unsigned int nr_segs)
{
if (!blk_queue_nomerges(q) && bio_mergeable(bio)) {
if (blk_attempt_plug_merge(q, bio, nr_segs))
return true;
if (blk_mq_sched_bio_merge(q, bio, nr_segs))
return true;
}
return false;
}
static struct request *blk_mq_get_new_requests(struct request_queue *q,
struct blk_plug *plug,
struct bio *bio,
unsigned int nsegs)
{
struct blk_mq_alloc_data data = {
.q = q,
.nr_tags = 1,
.cmd_flags = bio->bi_opf,
};
struct request *rq;
if (unlikely(bio_queue_enter(bio)))
return NULL;
if (blk_mq_attempt_bio_merge(q, bio, nsegs))
goto queue_exit;
rq_qos_throttle(q, bio);
if (plug) {
data.nr_tags = plug->nr_ios;
plug->nr_ios = 1;
data.cached_rq = &plug->cached_rq;
}
rq = __blk_mq_alloc_requests(&data);
if (rq)
return rq;
rq_qos_cleanup(q, bio);
if (bio->bi_opf & REQ_NOWAIT)
bio_wouldblock_error(bio);
queue_exit:
blk_queue_exit(q);
return NULL;
}
static inline struct request *blk_mq_get_cached_request(struct request_queue *q,
struct blk_plug *plug, struct bio **bio, unsigned int nsegs)
{
struct request *rq;
enum hctx_type type, hctx_type;
if (!plug)
return NULL;
rq = rq_list_peek(&plug->cached_rq);
if (!rq || rq->q != q)
return NULL;
if (blk_mq_attempt_bio_merge(q, *bio, nsegs)) {
*bio = NULL;
return NULL;
}
type = blk_mq_get_hctx_type((*bio)->bi_opf);
hctx_type = rq->mq_hctx->type;
if (type != hctx_type &&
!(type == HCTX_TYPE_READ && hctx_type == HCTX_TYPE_DEFAULT))
return NULL;
if (op_is_flush(rq->cmd_flags) != op_is_flush((*bio)->bi_opf))
return NULL;
/*
* If any qos ->throttle() end up blocking, we will have flushed the
* plug and hence killed the cached_rq list as well. Pop this entry
* before we throttle.
*/
plug->cached_rq = rq_list_next(rq);
rq_qos_throttle(q, *bio);
rq->cmd_flags = (*bio)->bi_opf;
INIT_LIST_HEAD(&rq->queuelist);
return rq;
}
static void bio_set_ioprio(struct bio *bio)
{
/* Nobody set ioprio so far? Initialize it based on task's nice value */
if (IOPRIO_PRIO_CLASS(bio->bi_ioprio) == IOPRIO_CLASS_NONE)
bio->bi_ioprio = get_current_ioprio();
blkcg_set_ioprio(bio);
}
/**
* blk_mq_submit_bio - Create and send a request to block device.
* @bio: Bio pointer.
*
* Builds up a request structure from @q and @bio and send to the device. The
* request may not be queued directly to hardware if:
* * This request can be merged with another one
* * We want to place request at plug queue for possible future merging
* * There is an IO scheduler active at this queue
*
* It will not queue the request if there is an error with the bio, or at the
* request creation.
*/
void blk_mq_submit_bio(struct bio *bio)
{
struct request_queue *q = bdev_get_queue(bio->bi_bdev);
struct blk_plug *plug = blk_mq_plug(bio);
const int is_sync = op_is_sync(bio->bi_opf);
struct request *rq;
unsigned int nr_segs = 1;
blk_status_t ret;
bio = blk_queue_bounce(bio, q);
if (bio_may_exceed_limits(bio, &q->limits)) {
bio = __bio_split_to_limits(bio, &q->limits, &nr_segs);
if (!bio)
return;
}
if (!bio_integrity_prep(bio))
return;
bio_set_ioprio(bio);
rq = blk_mq_get_cached_request(q, plug, &bio, nr_segs);
if (!rq) {
if (!bio)
return;
rq = blk_mq_get_new_requests(q, plug, bio, nr_segs);
if (unlikely(!rq))
return;
}
trace_block_getrq(bio);
rq_qos_track(q, rq, bio);
blk_mq_bio_to_request(rq, bio, nr_segs);
ret = blk_crypto_rq_get_keyslot(rq);
if (ret != BLK_STS_OK) {
bio->bi_status = ret;
bio_endio(bio);
blk_mq_free_request(rq);
return;
}
if (op_is_flush(bio->bi_opf)) {
blk_insert_flush(rq);
return;
}
if (plug)
blk_add_rq_to_plug(plug, rq);
else if ((rq->rq_flags & RQF_ELV) ||
(rq->mq_hctx->dispatch_busy &&
(q->nr_hw_queues == 1 || !is_sync)))
blk_mq_sched_insert_request(rq, false, true, true);
else
blk_mq_run_dispatch_ops(rq->q,
blk_mq_try_issue_directly(rq->mq_hctx, rq));
}
#ifdef CONFIG_BLK_MQ_STACKING
/**
* blk_insert_cloned_request - Helper for stacking drivers to submit a request
* @rq: the request being queued
*/
blk_status_t blk_insert_cloned_request(struct request *rq)
{
struct request_queue *q = rq->q;
unsigned int max_sectors = blk_queue_get_max_sectors(q, req_op(rq));
blk_status_t ret;
if (blk_rq_sectors(rq) > max_sectors) {
/*
* SCSI device does not have a good way to return if
* Write Same/Zero is actually supported. If a device rejects
* a non-read/write command (discard, write same,etc.) the
* low-level device driver will set the relevant queue limit to
* 0 to prevent blk-lib from issuing more of the offending
* operations. Commands queued prior to the queue limit being
* reset need to be completed with BLK_STS_NOTSUPP to avoid I/O
* errors being propagated to upper layers.
*/
if (max_sectors == 0)
return BLK_STS_NOTSUPP;
printk(KERN_ERR "%s: over max size limit. (%u > %u)\n",
__func__, blk_rq_sectors(rq), max_sectors);
return BLK_STS_IOERR;
}
/*
* The queue settings related to segment counting may differ from the
* original queue.
*/
rq->nr_phys_segments = blk_recalc_rq_segments(rq);
if (rq->nr_phys_segments > queue_max_segments(q)) {
printk(KERN_ERR "%s: over max segments limit. (%hu > %hu)\n",
__func__, rq->nr_phys_segments, queue_max_segments(q));
return BLK_STS_IOERR;
}
if (q->disk && should_fail_request(q->disk->part0, blk_rq_bytes(rq)))
return BLK_STS_IOERR;
if (blk_crypto_insert_cloned_request(rq))
return BLK_STS_IOERR;
blk_account_io_start(rq);
/*
* Since we have a scheduler attached on the top device,
* bypass a potential scheduler on the bottom device for
* insert.
*/
blk_mq_run_dispatch_ops(q,
ret = blk_mq_request_issue_directly(rq, true));
if (ret)
blk_account_io_done(rq, ktime_get_ns());
return ret;
}
EXPORT_SYMBOL_GPL(blk_insert_cloned_request);
/**
* blk_rq_unprep_clone - Helper function to free all bios in a cloned request
* @rq: the clone request to be cleaned up
*
* Description:
* Free all bios in @rq for a cloned request.
*/
void blk_rq_unprep_clone(struct request *rq)
{
struct bio *bio;
while ((bio = rq->bio) != NULL) {
rq->bio = bio->bi_next;
bio_put(bio);
}
}
EXPORT_SYMBOL_GPL(blk_rq_unprep_clone);
/**
* blk_rq_prep_clone - Helper function to setup clone request
* @rq: the request to be setup
* @rq_src: original request to be cloned
* @bs: bio_set that bios for clone are allocated from
* @gfp_mask: memory allocation mask for bio
* @bio_ctr: setup function to be called for each clone bio.
* Returns %0 for success, non %0 for failure.
* @data: private data to be passed to @bio_ctr
*
* Description:
* Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq.
* Also, pages which the original bios are pointing to are not copied
* and the cloned bios just point same pages.
* So cloned bios must be completed before original bios, which means
* the caller must complete @rq before @rq_src.
*/
int blk_rq_prep_clone(struct request *rq, struct request *rq_src,
struct bio_set *bs, gfp_t gfp_mask,
int (*bio_ctr)(struct bio *, struct bio *, void *),
void *data)
{
struct bio *bio, *bio_src;
if (!bs)
bs = &fs_bio_set;
__rq_for_each_bio(bio_src, rq_src) {
bio = bio_alloc_clone(rq->q->disk->part0, bio_src, gfp_mask,
bs);
if (!bio)
goto free_and_out;
if (bio_ctr && bio_ctr(bio, bio_src, data))
goto free_and_out;
if (rq->bio) {
rq->biotail->bi_next = bio;
rq->biotail = bio;
} else {
rq->bio = rq->biotail = bio;
}
bio = NULL;
}
/* Copy attributes of the original request to the clone request. */
rq->__sector = blk_rq_pos(rq_src);
rq->__data_len = blk_rq_bytes(rq_src);
if (rq_src->rq_flags & RQF_SPECIAL_PAYLOAD) {
rq->rq_flags |= RQF_SPECIAL_PAYLOAD;
rq->special_vec = rq_src->special_vec;
}
rq->nr_phys_segments = rq_src->nr_phys_segments;
rq->ioprio = rq_src->ioprio;
if (rq->bio && blk_crypto_rq_bio_prep(rq, rq->bio, gfp_mask) < 0)
goto free_and_out;
return 0;
free_and_out:
if (bio)
bio_put(bio);
blk_rq_unprep_clone(rq);
return -ENOMEM;
}
EXPORT_SYMBOL_GPL(blk_rq_prep_clone);
#endif /* CONFIG_BLK_MQ_STACKING */
/*
* Steal bios from a request and add them to a bio list.
* The request must not have been partially completed before.
*/
void blk_steal_bios(struct bio_list *list, struct request *rq)
{
if (rq->bio) {
if (list->tail)
list->tail->bi_next = rq->bio;
else
list->head = rq->bio;
list->tail = rq->biotail;
rq->bio = NULL;
rq->biotail = NULL;
}
rq->__data_len = 0;
}
EXPORT_SYMBOL_GPL(blk_steal_bios);
static size_t order_to_size(unsigned int order)
{
return (size_t)PAGE_SIZE << order;
}
/* called before freeing request pool in @tags */
static void blk_mq_clear_rq_mapping(struct blk_mq_tags *drv_tags,
struct blk_mq_tags *tags)
{
struct page *page;
unsigned long flags;
/*
* There is no need to clear mapping if driver tags is not initialized
* or the mapping belongs to the driver tags.
*/
if (!drv_tags || drv_tags == tags)
return;
list_for_each_entry(page, &tags->page_list, lru) {
unsigned long start = (unsigned long)page_address(page);
unsigned long end = start + order_to_size(page->private);
int i;
for (i = 0; i < drv_tags->nr_tags; i++) {
struct request *rq = drv_tags->rqs[i];
unsigned long rq_addr = (unsigned long)rq;
if (rq_addr >= start && rq_addr < end) {
WARN_ON_ONCE(req_ref_read(rq) != 0);
cmpxchg(&drv_tags->rqs[i], rq, NULL);
}
}
}
/*
* Wait until all pending iteration is done.
*
* Request reference is cleared and it is guaranteed to be observed
* after the ->lock is released.
*/
spin_lock_irqsave(&drv_tags->lock, f