summaryrefslogtreecommitdiffstats
path: root/block/blk-mq.c
diff options
context:
space:
mode:
Diffstat (limited to '')
-rw-r--r--block/blk-mq.c4981
1 files changed, 4981 insertions, 0 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c
new file mode 100644
index 000000000..b3f99dda4
--- /dev/null
+++ b/block/blk-mq.c
@@ -0,0 +1,4981 @@
+// 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_is_flush_data_rq(struct request *rq)
+{
+ return (rq->rq_flags & RQF_FLUSH_SEQ) && !is_flush_rq(rq);
+}
+
+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.
+ *
+ * In case of queue quiesce, if one flush data request is completed,
+ * don't count it as inflight given the flush sequence is suspended,
+ * and the original flush data request is invisible to driver, just
+ * like other pending requests because of quiesce
+ */
+ if (blk_mq_request_started(rq) && !(blk_queue_quiesced(rq->q) &&
+ blk_is_flush_data_rq(rq) &&
+ blk_mq_request_completed(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 (blk_mq_attempt_bio_merge(q, bio, nsegs))
+ return NULL;
+
+ 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);
+ return NULL;
+}
+
+/* return true if this @rq can be used for @bio */
+static bool blk_mq_can_use_cached_rq(struct request *rq, struct blk_plug *plug,
+ struct bio *bio)
+{
+ enum hctx_type type = blk_mq_get_hctx_type(bio->bi_opf);
+ enum hctx_type hctx_type = rq->mq_hctx->type;
+
+ WARN_ON_ONCE(rq_list_peek(&plug->cached_rq) != rq);
+
+ if (type != hctx_type &&
+ !(type == HCTX_TYPE_READ && hctx_type == HCTX_TYPE_DEFAULT))
+ return false;
+ if (op_is_flush(rq->cmd_flags) != op_is_flush(bio->bi_opf))
+ return false;
+
+ /*
+ * 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(rq->q, bio);
+
+ rq->cmd_flags = bio->bi_opf;
+ INIT_LIST_HEAD(&rq->queuelist);
+ return true;
+}
+
+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 = NULL;
+ unsigned int nr_segs = 1;
+ blk_status_t ret;
+
+ bio = blk_queue_bounce(bio, q);
+ bio_set_ioprio(bio);
+
+ if (plug) {
+ rq = rq_list_peek(&plug->cached_rq);
+ if (rq && rq->q != q)
+ rq = NULL;
+ }
+ if (rq) {
+ if (unlikely(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;
+ if (blk_mq_attempt_bio_merge(q, bio, nr_segs))
+ return;
+ if (blk_mq_can_use_cached_rq(rq, plug, bio))
+ goto done;
+ percpu_ref_get(&q->q_usage_counter);
+ } else {
+ if (unlikely(bio_queue_enter(bio)))
+ return;
+ if (unlikely(bio_may_exceed_limits(bio, &q->limits))) {
+ bio = __bio_split_to_limits(bio, &q->limits, &nr_segs);
+ if (!bio)
+ goto fail;
+ }
+ if (!bio_integrity_prep(bio))
+ goto fail;
+ }
+
+ rq = blk_mq_get_new_requests(q, plug, bio, nr_segs);
+ if (unlikely(!rq)) {
+fail:
+ blk_queue_exit(q);
+ return;
+ }
+
+done:
+ 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, flags);
+ spin_unlock_irqrestore(&drv_tags->lock, flags);
+}
+
+void blk_mq_free_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
+ unsigned int hctx_idx)
+{
+ struct blk_mq_tags *drv_tags;
+ struct page *page;
+
+ if (list_empty(&tags->page_list))
+ return;
+
+ if (blk_mq_is_shared_tags(set->flags))
+ drv_tags = set->shared_tags;
+ else
+ drv_tags = set->tags[hctx_idx];
+
+ if (tags->static_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;
+ }
+ }
+
+ blk_mq_clear_rq_mapping(drv_tags, tags);
+
+ 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_alloc_rqs().
+ */
+ 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);
+}
+
+static enum hctx_type hctx_idx_to_type(struct blk_mq_tag_set *set,
+ unsigned int hctx_idx)
+{
+ int i;
+
+ for (i = 0; i < set->nr_maps; i++) {
+ unsigned int start = set->map[i].queue_offset;
+ unsigned int end = start + set->map[i].nr_queues;
+
+ if (hctx_idx >= start && hctx_idx < end)
+ break;
+ }
+
+ if (i >= set->nr_maps)
+ i = HCTX_TYPE_DEFAULT;
+
+ return i;
+}
+
+static int blk_mq_get_hctx_node(struct blk_mq_tag_set *set,
+ unsigned int hctx_idx)
+{
+ enum hctx_type type = hctx_idx_to_type(set, hctx_idx);
+
+ return blk_mq_hw_queue_to_node(&set->map[type], hctx_idx);
+}
+
+static 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)
+{
+ int node = blk_mq_get_hctx_node(set, hctx_idx);
+ struct blk_mq_tags *tags;
+
+ 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 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;
+}
+
+static 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;
+ int node = blk_mq_get_hctx_node(set, hctx_idx);
+ size_t rq_size, left;
+
+ 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;
+}
+
+struct rq_iter_data {
+ struct blk_mq_hw_ctx *hctx;
+ bool has_rq;
+};
+
+static bool blk_mq_has_request(struct request *rq, void *data)
+{
+ struct rq_iter_data *iter_data = data;
+
+ if (rq->mq_hctx != iter_data->hctx)
+ return true;
+ iter_data->has_rq = true;
+ return false;
+}
+
+static bool blk_mq_hctx_has_requests(struct blk_mq_hw_ctx *hctx)
+{
+ struct blk_mq_tags *tags = hctx->sched_tags ?
+ hctx->sched_tags : hctx->tags;
+ struct rq_iter_data data = {
+ .hctx = hctx,
+ };
+
+ blk_mq_all_tag_iter(tags, blk_mq_has_request, &data);
+ return data.has_rq;
+}
+
+static inline bool blk_mq_last_cpu_in_hctx(unsigned int cpu,
+ struct blk_mq_hw_ctx *hctx)
+{
+ if (cpumask_first_and(hctx->cpumask, cpu_online_mask) != cpu)
+ return false;
+ if (cpumask_next_and(cpu, hctx->cpumask, cpu_online_mask) < nr_cpu_ids)
+ return false;
+ return true;
+}
+
+static int blk_mq_hctx_notify_offline(unsigned int cpu, struct hlist_node *node)
+{
+ struct blk_mq_hw_ctx *hctx = hlist_entry_safe(node,
+ struct blk_mq_hw_ctx, cpuhp_online);
+
+ if (!cpumask_test_cpu(cpu, hctx->cpumask) ||
+ !blk_mq_last_cpu_in_hctx(cpu, hctx))
+ return 0;
+
+ /*
+ * Prevent new request from being allocated on the current hctx.
+ *
+ * The smp_mb__after_atomic() Pairs with the implied barrier in
+ * test_and_set_bit_lock in sbitmap_get(). Ensures the inactive flag is
+ * seen once we return from the tag allocator.
+ */
+ set_bit(BLK_MQ_S_INACTIVE, &hctx->state);
+ smp_mb__after_atomic();
+
+ /*
+ * Try to grab a reference to the queue and wait for any outstanding
+ * requests. If we could not grab a reference the queue has been
+ * frozen and there are no requests.
+ */
+ if (percpu_ref_tryget(&hctx->queue->q_usage_counter)) {
+ while (blk_mq_hctx_has_requests(hctx))
+ msleep(5);
+ percpu_ref_put(&hctx->queue->q_usage_counter);
+ }
+
+ return 0;
+}
+
+static int blk_mq_hctx_notify_online(unsigned int cpu, struct hlist_node *node)
+{
+ struct blk_mq_hw_ctx *hctx = hlist_entry_safe(node,
+ struct blk_mq_hw_ctx, cpuhp_online);
+
+ if (cpumask_test_cpu(cpu, hctx->cpumask))
+ clear_bit(BLK_MQ_S_INACTIVE, &hctx->state);
+ return 0;
+}
+
+/*
+ * '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);
+ enum hctx_type type;
+
+ hctx = hlist_entry_safe(node, struct blk_mq_hw_ctx, cpuhp_dead);
+ if (!cpumask_test_cpu(cpu, hctx->cpumask))
+ return 0;
+
+ ctx = __blk_mq_get_ctx(hctx->queue, cpu);
+ type = hctx->type;
+
+ spin_lock(&ctx->lock);
+ if (!list_empty(&ctx->rq_lists[type])) {
+ list_splice_init(&ctx->rq_lists[type], &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)
+{
+ if (!(hctx->flags & BLK_MQ_F_STACKING))
+ cpuhp_state_remove_instance_nocalls(CPUHP_AP_BLK_MQ_ONLINE,
+ &hctx->cpuhp_online);
+ cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD,
+ &hctx->cpuhp_dead);
+}
+
+/*
+ * Before freeing hw queue, clearing the flush request reference in
+ * tags->rqs[] for avoiding potential UAF.
+ */
+static void blk_mq_clear_flush_rq_mapping(struct blk_mq_tags *tags,
+ unsigned int queue_depth, struct request *flush_rq)
+{
+ int i;
+ unsigned long flags;
+
+ /* The hw queue may not be mapped yet */
+ if (!tags)
+ return;
+
+ WARN_ON_ONCE(req_ref_read(flush_rq) != 0);
+
+ for (i = 0; i < queue_depth; i++)
+ cmpxchg(&tags->rqs[i], flush_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(&tags->lock, flags);
+ spin_unlock_irqrestore(&tags->lock, flags);
+}
+
+/* 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)
+{
+ struct request *flush_rq = hctx->fq->flush_rq;
+
+ if (blk_mq_hw_queue_mapped(hctx))
+ blk_mq_tag_idle(hctx);
+
+ if (blk_queue_init_done(q))
+ blk_mq_clear_flush_rq_mapping(set->tags[hctx_idx],
+ set->queue_depth, flush_rq);
+ if (set->ops->exit_request)
+ set->ops->exit_request(set, flush_rq, hctx_idx);
+
+ if (set->ops->exit_hctx)
+ set->ops->exit_hctx(hctx, hctx_idx);
+
+ blk_mq_remove_cpuhp(hctx);
+
+ xa_erase(&q->hctx_table, hctx_idx);
+
+ spin_lock(&q->unused_hctx_lock);
+ list_add(&hctx->hctx_list, &q->unused_hctx_list);
+ spin_unlock(&q->unused_hctx_lock);
+}
+
+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 long i;
+
+ queue_for_each_hw_ctx(q, hctx, i) {
+ if (i == nr_queue)
+ break;
+ 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)
+{
+ hctx->queue_num = hctx_idx;
+
+ if (!(hctx->flags & BLK_MQ_F_STACKING))
+ cpuhp_state_add_instance_nocalls(CPUHP_AP_BLK_MQ_ONLINE,
+ &hctx->cpuhp_online);
+ cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD, &hctx->cpuhp_dead);
+
+ hctx->tags = set->tags[hctx_idx];
+
+ if (set->ops->init_hctx &&
+ set->ops->init_hctx(hctx, set->driver_data, hctx_idx))
+ goto unregister_cpu_notifier;
+
+ if (blk_mq_init_request(set, hctx->fq->flush_rq, hctx_idx,
+ hctx->numa_node))
+ goto exit_hctx;
+
+ if (xa_insert(&q->hctx_table, hctx_idx, hctx, GFP_KERNEL))
+ goto exit_flush_rq;
+
+ return 0;
+
+ exit_flush_rq:
+ if (set->ops->exit_request)
+ set->ops->exit_request(set, hctx->fq->flush_rq, hctx_idx);
+ exit_hctx:
+ if (set->ops->exit_hctx)
+ set->ops->exit_hctx(hctx, hctx_idx);
+ unregister_cpu_notifier:
+ blk_mq_remove_cpuhp(hctx);
+ return -1;
+}
+
+static struct blk_mq_hw_ctx *
+blk_mq_alloc_hctx(struct request_queue *q, struct blk_mq_tag_set *set,
+ int node)
+{
+ struct blk_mq_hw_ctx *hctx;
+ gfp_t gfp = GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY;
+
+ hctx = kzalloc_node(sizeof(struct blk_mq_hw_ctx), gfp, node);
+ if (!hctx)
+ goto fail_alloc_hctx;
+
+ if (!zalloc_cpumask_var_node(&hctx->cpumask, gfp, node))
+ goto free_hctx;
+
+ atomic_set(&hctx->nr_active, 0);
+ if (node == NUMA_NO_NODE)
+ node = set->numa_node;
+ hctx->numa_node = 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_QUEUE_SHARED;
+
+ INIT_LIST_HEAD(&hctx->hctx_list);
+
+ /*
+ * Allocate space for all possible cpus to avoid allocation at
+ * runtime
+ */
+ hctx->ctxs = kmalloc_array_node(nr_cpu_ids, sizeof(void *),
+ gfp, node);
+ if (!hctx->ctxs)
+ goto free_cpumask;
+
+ if (sbitmap_init_node(&hctx->ctx_map, nr_cpu_ids, ilog2(8),
+ gfp, node, false, false))
+ 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);
+
+ hctx->fq = blk_alloc_flush_queue(hctx->numa_node, set->cmd_size, gfp);
+ if (!hctx->fq)
+ goto free_bitmap;
+
+ blk_mq_hctx_kobj_init(hctx);
+
+ return hctx;
+
+ free_bitmap:
+ sbitmap_free(&hctx->ctx_map);
+ free_ctxs:
+ kfree(hctx->ctxs);
+ free_cpumask:
+ free_cpumask_var(hctx->cpumask);
+ free_hctx:
+ kfree(hctx);
+ fail_alloc_hctx:
+ return NULL;
+}
+
+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;
+ int k;
+
+ __ctx->cpu = i;
+ spin_lock_init(&__ctx->lock);
+ for (k = HCTX_TYPE_DEFAULT; k < HCTX_MAX_TYPES; k++)
+ INIT_LIST_HEAD(&__ctx->rq_lists[k]);
+
+ __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 = cpu_to_node(i);
+ }
+ }
+}
+
+struct blk_mq_tags *blk_mq_alloc_map_and_rqs(struct blk_mq_tag_set *set,
+ unsigned int hctx_idx,
+ unsigned int depth)
+{
+ struct blk_mq_tags *tags;
+ int ret;
+
+ tags = blk_mq_alloc_rq_map(set, hctx_idx, depth, set->reserved_tags);
+ if (!tags)
+ return NULL;
+
+ ret = blk_mq_alloc_rqs(set, tags, hctx_idx, depth);
+ if (ret) {
+ blk_mq_free_rq_map(tags);
+ return NULL;
+ }
+
+ return tags;
+}
+
+static bool __blk_mq_alloc_map_and_rqs(struct blk_mq_tag_set *set,
+ int hctx_idx)
+{
+ if (blk_mq_is_shared_tags(set->flags)) {
+ set->tags[hctx_idx] = set->shared_tags;
+
+ return true;
+ }
+
+ set->tags[hctx_idx] = blk_mq_alloc_map_and_rqs(set, hctx_idx,
+ set->queue_depth);
+
+ return set->tags[hctx_idx];
+}
+
+void blk_mq_free_map_and_rqs(struct blk_mq_tag_set *set,
+ struct blk_mq_tags *tags,
+ unsigned int hctx_idx)
+{
+ if (tags) {
+ blk_mq_free_rqs(set, tags, hctx_idx);
+ blk_mq_free_rq_map(tags);
+ }
+}
+
+static void __blk_mq_free_map_and_rqs(struct blk_mq_tag_set *set,
+ unsigned int hctx_idx)
+{
+ if (!blk_mq_is_shared_tags(set->flags))
+ blk_mq_free_map_and_rqs(set, set->tags[hctx_idx], hctx_idx);
+
+ set->tags[hctx_idx] = NULL;
+}
+
+static void blk_mq_map_swqueue(struct request_queue *q)
+{
+ unsigned int j, hctx_idx;
+ unsigned long i;
+ struct blk_mq_hw_ctx *hctx;
+ struct blk_mq_ctx *ctx;
+ struct blk_mq_tag_set *set = q->tag_set;
+
+ 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) {
+
+ ctx = per_cpu_ptr(q->queue_ctx, i);
+ for (j = 0; j < set->nr_maps; j++) {
+ if (!set->map[j].nr_queues) {
+ ctx->hctxs[j] = blk_mq_map_queue_type(q,
+ HCTX_TYPE_DEFAULT, i);
+ continue;
+ }
+ hctx_idx = set->map[j].mq_map[i];
+ /* unmapped hw queue can be remapped after CPU topo changed */
+ if (!set->tags[hctx_idx] &&
+ !__blk_mq_alloc_map_and_rqs(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[j].mq_map[i] = 0;
+ }
+
+ hctx = blk_mq_map_queue_type(q, j, i);
+ ctx->hctxs[j] = hctx;
+ /*
+ * 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);
+ }
+
+ for (; j < HCTX_MAX_TYPES; j++)
+ ctx->hctxs[j] = blk_mq_map_queue_type(q,
+ HCTX_TYPE_DEFAULT, i);
+ }
+
+ 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)
+ __blk_mq_free_map_and_rqs(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;
+ unsigned long i;
+
+ queue_for_each_hw_ctx(q, hctx, i) {
+ if (shared) {
+ hctx->flags |= BLK_MQ_F_TAG_QUEUE_SHARED;
+ } else {
+ blk_mq_tag_idle(hctx);
+ hctx->flags &= ~BLK_MQ_F_TAG_QUEUE_SHARED;
+ }
+ }
+}
+
+static void blk_mq_update_tag_set_shared(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(&q->tag_set_list);
+ if (list_is_singular(&set->tag_list)) {
+ /* just transitioned to unshared */
+ set->flags &= ~BLK_MQ_F_TAG_QUEUE_SHARED;
+ /* update existing queue */
+ blk_mq_update_tag_set_shared(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_QUEUE_SHARED)) {
+ set->flags |= BLK_MQ_F_TAG_QUEUE_SHARED;
+ /* update existing queue */
+ blk_mq_update_tag_set_shared(set, true);
+ }
+ if (set->flags & BLK_MQ_F_TAG_QUEUE_SHARED)
+ queue_set_hctx_shared(q, true);
+ list_add_tail(&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, *next;
+ unsigned long i;
+
+ queue_for_each_hw_ctx(q, hctx, i)
+ WARN_ON_ONCE(hctx && list_empty(&hctx->hctx_list));
+
+ /* all hctx are in .unused_hctx_list now */
+ list_for_each_entry_safe(hctx, next, &q->unused_hctx_list, hctx_list) {
+ list_del_init(&hctx->hctx_list);
+ kobject_put(&hctx->kobj);
+ }
+
+ xa_destroy(&q->hctx_table);
+
+ /*
+ * release .mq_kobj and sw queue's kobject now because
+ * both share lifetime with request queue.
+ */
+ blk_mq_sysfs_deinit(q);
+}
+
+static struct request_queue *blk_mq_init_queue_data(struct blk_mq_tag_set *set,
+ void *queuedata)
+{
+ struct request_queue *q;
+ int ret;
+
+ q = blk_alloc_queue(set->numa_node, set->flags & BLK_MQ_F_BLOCKING);
+ if (!q)
+ return ERR_PTR(-ENOMEM);
+ q->queuedata = queuedata;
+ ret = blk_mq_init_allocated_queue(set, q);
+ if (ret) {
+ blk_put_queue(q);
+ return ERR_PTR(ret);
+ }
+ return q;
+}
+
+struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
+{
+ return blk_mq_init_queue_data(set, NULL);
+}
+EXPORT_SYMBOL(blk_mq_init_queue);
+
+/**
+ * blk_mq_destroy_queue - shutdown a request queue
+ * @q: request queue to shutdown
+ *
+ * This shuts down a request queue allocated by blk_mq_init_queue() and drops
+ * the initial reference. All future requests will failed with -ENODEV.
+ *
+ * Context: can sleep
+ */
+void blk_mq_destroy_queue(struct request_queue *q)
+{
+ WARN_ON_ONCE(!queue_is_mq(q));
+ WARN_ON_ONCE(blk_queue_registered(q));
+
+ might_sleep();
+
+ blk_queue_flag_set(QUEUE_FLAG_DYING, q);
+ blk_queue_start_drain(q);
+ blk_freeze_queue(q);
+
+ blk_sync_queue(q);
+ blk_mq_cancel_work_sync(q);
+ blk_mq_exit_queue(q);
+
+ /* @q is and will stay empty, shutdown and put */
+ blk_put_queue(q);
+}
+EXPORT_SYMBOL(blk_mq_destroy_queue);
+
+struct gendisk *__blk_mq_alloc_disk(struct blk_mq_tag_set *set, void *queuedata,
+ struct lock_class_key *lkclass)
+{
+ struct request_queue *q;
+ struct gendisk *disk;
+
+ q = blk_mq_init_queue_data(set, queuedata);
+ if (IS_ERR(q))
+ return ERR_CAST(q);
+
+ disk = __alloc_disk_node(q, set->numa_node, lkclass);
+ if (!disk) {
+ blk_mq_destroy_queue(q);
+ return ERR_PTR(-ENOMEM);
+ }
+ set_bit(GD_OWNS_QUEUE, &disk->state);
+ return disk;
+}
+EXPORT_SYMBOL(__blk_mq_alloc_disk);
+
+struct gendisk *blk_mq_alloc_disk_for_queue(struct request_queue *q,
+ struct lock_class_key *lkclass)
+{
+ struct gendisk *disk;
+
+ if (!blk_get_queue(q))
+ return NULL;
+ disk = __alloc_disk_node(q, NUMA_NO_NODE, lkclass);
+ if (!disk)
+ blk_put_queue(q);
+ return disk;
+}
+EXPORT_SYMBOL(blk_mq_alloc_disk_for_queue);
+
+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 = NULL, *tmp;
+
+ /* reuse dead hctx first */
+ spin_lock(&q->unused_hctx_lock);
+ list_for_each_entry(tmp, &q->unused_hctx_list, hctx_list) {
+ if (tmp->numa_node == node) {
+ hctx = tmp;
+ break;
+ }
+ }
+ if (hctx)
+ list_del_init(&hctx->hctx_list);
+ spin_unlock(&q->unused_hctx_lock);
+
+ if (!hctx)
+ hctx = blk_mq_alloc_hctx(q, set, node);
+ if (!hctx)
+ goto fail;
+
+ if (blk_mq_init_hctx(q, set, hctx, hctx_idx))
+ goto free_hctx;
+
+ return hctx;
+
+ free_hctx:
+ kobject_put(&hctx->kobj);
+ fail:
+ return NULL;
+}
+
+static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set,
+ struct request_queue *q)
+{
+ struct blk_mq_hw_ctx *hctx;
+ unsigned long i, j;
+
+ /* protect against switching io scheduler */
+ mutex_lock(&q->sysfs_lock);
+ for (i = 0; i < set->nr_hw_queues; i++) {
+ int old_node;
+ int node = blk_mq_get_hctx_node(set, i);
+ struct blk_mq_hw_ctx *old_hctx = xa_load(&q->hctx_table, i);
+
+ if (old_hctx) {
+ old_node = old_hctx->numa_node;
+ blk_mq_exit_hctx(q, set, old_hctx, i);
+ }
+
+ if (!blk_mq_alloc_and_init_hctx(set, q, i, node)) {
+ if (!old_hctx)
+ break;
+ pr_warn("Allocate new hctx on node %d fails, fallback to previous one on node %d\n",
+ node, old_node);
+ hctx = blk_mq_alloc_and_init_hctx(set, q, i, old_node);
+ WARN_ON_ONCE(!hctx);
+ }
+ }
+ /*
+ * 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;
+ } else {
+ j = i;
+ q->nr_hw_queues = set->nr_hw_queues;
+ }
+
+ xa_for_each_start(&q->hctx_table, j, hctx, j)
+ blk_mq_exit_hctx(q, set, hctx, j);
+ mutex_unlock(&q->sysfs_lock);
+}
+
+static void blk_mq_update_poll_flag(struct request_queue *q)
+{
+ struct blk_mq_tag_set *set = q->tag_set;
+
+ if (set->nr_maps > HCTX_TYPE_POLL &&
+ set->map[HCTX_TYPE_POLL].nr_queues)
+ blk_queue_flag_set(QUEUE_FLAG_POLL, q);
+ else
+ blk_queue_flag_clear(QUEUE_FLAG_POLL, q);
+}
+
+int blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
+ struct request_queue *q)
+{
+ WARN_ON_ONCE(blk_queue_has_srcu(q) !=
+ !!(set->flags & BLK_MQ_F_BLOCKING));
+
+ /* 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_poll;
+
+ /* init q->mq_kobj and sw queues' kobjects */
+ blk_mq_sysfs_init(q);
+
+ INIT_LIST_HEAD(&q->unused_hctx_list);
+ spin_lock_init(&q->unused_hctx_lock);
+
+ xa_init(&q->hctx_table);
+
+ 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;
+ blk_mq_update_poll_flag(q);
+
+ INIT_DELAYED_WORK(&q->requeue_work, blk_mq_requeue_work);
+ INIT_LIST_HEAD(&q->requeue_list);
+ spin_lock_init(&q->requeue_lock);
+
+ q->nr_requests = set->queue_depth;
+
+ /*
+ * Default to classic polling
+ */
+ q->poll_nsec = BLK_MQ_POLL_CLASSIC;
+
+ blk_mq_init_cpu_queues(q, set->nr_hw_queues);
+ blk_mq_add_queue_tag_set(set, q);
+ blk_mq_map_swqueue(q);
+ return 0;
+
+err_hctxs:
+ blk_mq_release(q);
+err_poll:
+ blk_stat_free_callback(q->poll_cb);
+ q->poll_cb = NULL;
+err_exit:
+ q->mq_ops = NULL;
+ return -ENOMEM;
+}
+EXPORT_SYMBOL(blk_mq_init_allocated_queue);
+
+/* tags can _not_ be used after returning from blk_mq_exit_queue */
+void blk_mq_exit_queue(struct request_queue *q)
+{
+ struct blk_mq_tag_set *set = q->tag_set;
+
+ /* Checks hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED. */
+ blk_mq_exit_hw_queues(q, set, set->nr_hw_queues);
+ /* May clear BLK_MQ_F_TAG_QUEUE_SHARED in hctx->flags. */
+ blk_mq_del_queue_tag_set(q);
+}
+
+static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
+{
+ int i;
+
+ if (blk_mq_is_shared_tags(set->flags)) {
+ set->shared_tags = blk_mq_alloc_map_and_rqs(set,
+ BLK_MQ_NO_HCTX_IDX,
+ set->queue_depth);
+ if (!set->shared_tags)
+ return -ENOMEM;
+ }
+
+ for (i = 0; i < set->nr_hw_queues; i++) {
+ if (!__blk_mq_alloc_map_and_rqs(set, i))
+ goto out_unwind;
+ cond_resched();
+ }
+
+ return 0;
+
+out_unwind:
+ while (--i >= 0)
+ __blk_mq_free_map_and_rqs(set, i);
+
+ if (blk_mq_is_shared_tags(set->flags)) {
+ blk_mq_free_map_and_rqs(set, set->shared_tags,
+ BLK_MQ_NO_HCTX_IDX);
+ }
+
+ 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_set_map_and_rqs(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 void blk_mq_update_queue_map(struct blk_mq_tag_set *set)
+{
+ /*
+ * blk_mq_map_queues() and multiple .map_queues() implementations
+ * expect that set->map[HCTX_TYPE_DEFAULT].nr_queues is set to the
+ * number of hardware queues.
+ */
+ if (set->nr_maps == 1)
+ set->map[HCTX_TYPE_DEFAULT].nr_queues = set->nr_hw_queues;
+
+ if (set->ops->map_queues && !is_kdump_kernel()) {
+ 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]);
+
+ set->ops->map_queues(set);
+ } else {
+ BUG_ON(set->nr_maps > 1);
+ blk_mq_map_queues(&set->map[HCTX_TYPE_DEFAULT]);
+ }
+}
+
+static int blk_mq_realloc_tag_set_tags(struct blk_mq_tag_set *set,
+ int cur_nr_hw_queues, int new_nr_hw_queues)
+{
+ struct blk_mq_tags **new_tags;
+
+ if (cur_nr_hw_queues >= new_nr_hw_queues)
+ return 0;
+
+ new_tags = kcalloc_node(new_nr_hw_queues, sizeof(struct blk_mq_tags *),
+ GFP_KERNEL, set->numa_node);
+ if (!new_tags)
+ return -ENOMEM;
+
+ if (set->tags)
+ memcpy(new_tags, set->tags, cur_nr_hw_queues *
+ sizeof(*set->tags));
+ kfree(set->tags);
+ set->tags = new_tags;
+ set->nr_hw_queues = new_nr_hw_queues;
+
+ return 0;
+}
+
+static int blk_mq_alloc_tag_set_tags(struct blk_mq_tag_set *set,
+ int new_nr_hw_queues)
+{
+ return blk_mq_realloc_tag_set_tags(set, 0, new_nr_hw_queues);
+}
+
+/*
+ * 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->nr_maps = 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;
+
+ if (blk_mq_alloc_tag_set_tags(set, set->nr_hw_queues) < 0)
+ return -ENOMEM;
+
+ ret = -ENOMEM;
+ for (i = 0; i < set->nr_maps; i++) {
+ set->map[i].mq_map = kcalloc_node(nr_cpu_ids,
+ sizeof(set->map[i].mq_map[0]),
+ GFP_KERNEL, set->numa_node);
+ if (!set->map[i].mq_map)
+ goto out_free_mq_map;
+ set->map[i].nr_queues = is_kdump_kernel() ? 1 : set->nr_hw_queues;
+ }
+
+ blk_mq_update_queue_map(set);
+
+ ret = blk_mq_alloc_set_map_and_rqs(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);
+
+/* allocate and initialize a tagset for a simple single-queue device */
+int blk_mq_alloc_sq_tag_set(struct blk_mq_tag_set *set,
+ const struct blk_mq_ops *ops, unsigned int queue_depth,
+ unsigned int set_flags)
+{
+ 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;
+ return blk_mq_alloc_tag_set(set);
+}
+EXPORT_SYMBOL_GPL(blk_mq_alloc_sq_tag_set);
+
+void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
+{
+ int i, j;
+
+ for (i = 0; i < set->nr_hw_queues; i++)
+ __blk_mq_free_map_and_rqs(set, i);
+
+ if (blk_mq_is_shared_tags(set->flags)) {
+ blk_mq_free_map_and_rqs(set, set->shared_tags,
+ BLK_MQ_NO_HCTX_IDX);
+ }
+
+ 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 ret;
+ unsigned long i;
+
+ if (!set)
+ return -EINVAL;
+
+ if (q->nr_requests == nr)
+ return 0;
+
+ 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->sched_tags,
+ nr, true);
+ } else {
+ ret = blk_mq_tag_update_depth(hctx, &hctx->tags, nr,
+ false);
+ }
+ if (ret)
+ break;
+ if (q->elevator && q->elevator->type->ops.depth_updated)
+ q->elevator->type->ops.depth_updated(hctx);
+ }
+ if (!ret) {
+ q->nr_requests = nr;
+ if (blk_mq_is_shared_tags(set->flags)) {
+ if (q->elevator)
+ blk_mq_tag_update_sched_shared_tags(q);
+ else
+ blk_mq_tag_resize_shared_tags(set, 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;
+
+ /* q->elevator needs protection from ->sysfs_lock */
+ mutex_lock(&q->sysfs_lock);
+
+ INIT_LIST_HEAD(&qe->node);
+ qe->q = q;
+ qe->type = q->elevator->type;
+ list_add(&qe->node, head);
+
+ /*
+ * After elevator_switch, 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(q, NULL);
+ mutex_unlock(&q->sysfs_lock);
+
+ return true;
+}
+
+static struct blk_mq_qe_pair *blk_lookup_qe_pair(struct list_head *head,
+ struct request_queue *q)
+{
+ struct blk_mq_qe_pair *qe;
+
+ list_for_each_entry(qe, head, node)
+ if (qe->q == q)
+ return qe;
+
+ return NULL;
+}
+
+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;
+
+ qe = blk_lookup_qe_pair(head, q);
+ if (!qe)
+ return;
+ t = qe->type;
+ list_del(&qe->node);
+ kfree(qe);
+
+ mutex_lock(&q->sysfs_lock);
+ elevator_switch(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)
+ return;
+ if (set->nr_maps == 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);
+ /*
+ * 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_hctxs(q);
+ }
+
+ prev_nr_hw_queues = set->nr_hw_queues;
+ if (blk_mq_realloc_tag_set_tags(set, set->nr_hw_queues, nr_hw_queues) <
+ 0)
+ goto reregister;
+
+ set->nr_hw_queues = nr_hw_queues;
+fallback:
+ blk_mq_update_queue_map(set);
+ list_for_each_entry(q, &set->tag_list, tag_set_list) {
+ blk_mq_realloc_hw_ctxs(set, q);
+ blk_mq_update_poll_flag(q);
+ if (q->nr_hw_queues != set->nr_hw_queues) {
+ int i = prev_nr_hw_queues;
+
+ pr_warn("Increasing nr_hw_queues to %d fails, fallback to %d\n",
+ nr_hw_queues, prev_nr_hw_queues);
+ for (; i < set->nr_hw_queues; i++)
+ __blk_mq_free_map_and_rqs(set, i);
+
+ set->nr_hw_queues = prev_nr_hw_queues;
+ blk_mq_map_queues(&set->map[HCTX_TYPE_DEFAULT]);
+ goto fallback;
+ }
+ blk_mq_map_swqueue(q);
+ }
+
+reregister:
+ list_for_each_entry(q, &set->tag_list, tag_set_list) {
+ blk_mq_sysfs_register_hctxs(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 (q->poll_stat)
+ return true;
+
+ return blk_stats_alloc_enable(q);
+}
+
+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 (!q->poll_stat || 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 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(struct request_queue *q, blk_qc_t qc)
+{
+ struct blk_mq_hw_ctx *hctx = blk_qc_to_hctx(q, qc);
+ struct request *rq = blk_qc_to_rq(hctx, qc);
+ struct hrtimer_sleeper hs;
+ enum hrtimer_mode mode;
+ unsigned int nsecs;
+ ktime_t kt;
+
+ /*
+ * If a request has completed on queue that uses an I/O scheduler, we
+ * won't get back a request from blk_qc_to_rq.
+ */
+ if (!rq || (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, 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_sleeper_on_stack(&hs, CLOCK_MONOTONIC, mode);
+ hrtimer_set_expires(&hs.timer, kt);
+
+ do {
+ if (blk_mq_rq_state(rq) == MQ_RQ_COMPLETE)
+ break;
+ set_current_state(TASK_UNINTERRUPTIBLE);
+ hrtimer_sleeper_start_expires(&hs, 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);
+
+ /*
+ * 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.
+ */
+ return true;
+}
+
+static int blk_mq_poll_classic(struct request_queue *q, blk_qc_t cookie,
+ struct io_comp_batch *iob, unsigned int flags)
+{
+ struct blk_mq_hw_ctx *hctx = blk_qc_to_hctx(q, cookie);
+ long state = get_current_state();
+ int ret;
+
+ do {
+ ret = q->mq_ops->poll(hctx, iob);
+ if (ret > 0) {
+ __set_current_state(TASK_RUNNING);
+ return ret;
+ }
+
+ if (signal_pending_state(state, current))
+ __set_current_state(TASK_RUNNING);
+ if (task_is_running(current))
+ return 1;
+
+ if (ret < 0 || (flags & BLK_POLL_ONESHOT))
+ break;
+ cpu_relax();
+ } while (!need_resched());
+
+ __set_current_state(TASK_RUNNING);
+ return 0;
+}
+
+int blk_mq_poll(struct request_queue *q, blk_qc_t cookie, struct io_comp_batch *iob,
+ unsigned int flags)
+{
+ if (!(flags & BLK_POLL_NOSLEEP) &&
+ q->poll_nsec != BLK_MQ_POLL_CLASSIC) {
+ if (blk_mq_poll_hybrid(q, cookie))
+ return 1;
+ }
+ return blk_mq_poll_classic(q, cookie, iob, flags);
+}
+
+unsigned int blk_mq_rq_cpu(struct request *rq)
+{
+ return rq->mq_ctx->cpu;
+}
+EXPORT_SYMBOL(blk_mq_rq_cpu);
+
+void blk_mq_cancel_work_sync(struct request_queue *q)
+{
+ if (queue_is_mq(q)) {
+ struct blk_mq_hw_ctx *hctx;
+ unsigned long i;
+
+ cancel_delayed_work_sync(&q->requeue_work);
+
+ queue_for_each_hw_ctx(q, hctx, i)
+ cancel_delayed_work_sync(&hctx->run_work);
+ }
+}
+
+static int __init blk_mq_init(void)
+{
+ int i;
+
+ for_each_possible_cpu(i)
+ init_llist_head(&per_cpu(blk_cpu_done, i));
+ open_softirq(BLOCK_SOFTIRQ, blk_done_softirq);
+
+ cpuhp_setup_state_nocalls(CPUHP_BLOCK_SOFTIRQ_DEAD,
+ "block/softirq:dead", NULL,
+ blk_softirq_cpu_dead);
+ cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD, "block/mq:dead", NULL,
+ blk_mq_hctx_notify_dead);
+ cpuhp_setup_state_multi(CPUHP_AP_BLK_MQ_ONLINE, "block/mq:online",
+ blk_mq_hctx_notify_online,
+ blk_mq_hctx_notify_offline);
+ return 0;
+}
+subsys_initcall(blk_mq_init);