diff options
Diffstat (limited to '')
| -rw-r--r-- | block/blk-mq.c | 3238 |
1 files changed, 3238 insertions, 0 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c new file mode 100644 index 000000000..ae70b4809 --- /dev/null +++ b/block/blk-mq.c @@ -0,0 +1,3238 @@ +/* + * Block multiqueue core code + * + * Copyright (C) 2013-2014 Jens Axboe + * Copyright (C) 2013-2014 Christoph Hellwig + */ +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/backing-dev.h> +#include <linux/bio.h> +#include <linux/blkdev.h> +#include <linux/kmemleak.h> +#include <linux/mm.h> +#include <linux/init.h> +#include <linux/slab.h> +#include <linux/workqueue.h> +#include <linux/smp.h> +#include <linux/llist.h> +#include <linux/list_sort.h> +#include <linux/cpu.h> +#include <linux/cache.h> +#include <linux/sched/sysctl.h> +#include <linux/sched/topology.h> +#include <linux/sched/signal.h> +#include <linux/delay.h> +#include <linux/crash_dump.h> +#include <linux/prefetch.h> + +#include <trace/events/block.h> + +#include <linux/blk-mq.h> +#include "blk.h" +#include "blk-mq.h" +#include "blk-mq-debugfs.h" +#include "blk-mq-tag.h" +#include "blk-stat.h" +#include "blk-mq-sched.h" +#include "blk-rq-qos.h" + +static bool blk_mq_poll(struct request_queue *q, blk_qc_t cookie); +static void blk_mq_poll_stats_start(struct request_queue *q); +static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb); + +static int blk_mq_poll_stats_bkt(const struct request *rq) +{ + int ddir, bytes, bucket; + + ddir = rq_data_dir(rq); + bytes = blk_rq_bytes(rq); + + bucket = ddir + 2*(ilog2(bytes) - 9); + + if (bucket < 0) + return -1; + else if (bucket >= BLK_MQ_POLL_STATS_BKTS) + return ddir + BLK_MQ_POLL_STATS_BKTS - 2; + + return bucket; +} + +/* + * Check if any of the ctx's have pending work in this hardware queue + */ +static bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx *hctx) +{ + return !list_empty_careful(&hctx->dispatch) || + sbitmap_any_bit_set(&hctx->ctx_map) || + blk_mq_sched_has_work(hctx); +} + +/* + * Mark this ctx as having pending work in this hardware queue + */ +static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx *hctx, + struct blk_mq_ctx *ctx) +{ + if (!sbitmap_test_bit(&hctx->ctx_map, ctx->index_hw)) + sbitmap_set_bit(&hctx->ctx_map, ctx->index_hw); +} + +static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx *hctx, + struct blk_mq_ctx *ctx) +{ + sbitmap_clear_bit(&hctx->ctx_map, ctx->index_hw); +} + +struct mq_inflight { + struct hd_struct *part; + unsigned int *inflight; +}; + +static void blk_mq_check_inflight(struct blk_mq_hw_ctx *hctx, + struct request *rq, void *priv, + bool reserved) +{ + struct mq_inflight *mi = priv; + + /* + * index[0] counts the specific partition that was asked for. index[1] + * counts the ones that are active on the whole device, so increment + * that if mi->part is indeed a partition, and not a whole device. + */ + if (rq->part == mi->part) + mi->inflight[0]++; + if (mi->part->partno) + mi->inflight[1]++; +} + +void blk_mq_in_flight(struct request_queue *q, struct hd_struct *part, + unsigned int inflight[2]) +{ + struct mq_inflight mi = { .part = part, .inflight = inflight, }; + + inflight[0] = inflight[1] = 0; + blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight, &mi); +} + +static void blk_mq_check_inflight_rw(struct blk_mq_hw_ctx *hctx, + struct request *rq, void *priv, + bool reserved) +{ + struct mq_inflight *mi = priv; + + if (rq->part == mi->part) + mi->inflight[rq_data_dir(rq)]++; +} + +void blk_mq_in_flight_rw(struct request_queue *q, struct hd_struct *part, + unsigned int inflight[2]) +{ + struct mq_inflight mi = { .part = part, .inflight = inflight, }; + + inflight[0] = inflight[1] = 0; + blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight_rw, &mi); +} + +void blk_freeze_queue_start(struct request_queue *q) +{ + int freeze_depth; + + freeze_depth = atomic_inc_return(&q->mq_freeze_depth); + if (freeze_depth == 1) { + percpu_ref_kill(&q->q_usage_counter); + if (q->mq_ops) + blk_mq_run_hw_queues(q, false); + } +} +EXPORT_SYMBOL_GPL(blk_freeze_queue_start); + +void blk_mq_freeze_queue_wait(struct request_queue *q) +{ + wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->q_usage_counter)); +} +EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait); + +int blk_mq_freeze_queue_wait_timeout(struct request_queue *q, + unsigned long timeout) +{ + return wait_event_timeout(q->mq_freeze_wq, + percpu_ref_is_zero(&q->q_usage_counter), + timeout); +} +EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_wait_timeout); + +/* + * Guarantee no request is in use, so we can change any data structure of + * the queue afterward. + */ +void blk_freeze_queue(struct request_queue *q) +{ + /* + * In the !blk_mq case we are only calling this to kill the + * q_usage_counter, otherwise this increases the freeze depth + * and waits for it to return to zero. For this reason there is + * no blk_unfreeze_queue(), and blk_freeze_queue() is not + * exported to drivers as the only user for unfreeze is blk_mq. + */ + blk_freeze_queue_start(q); + if (!q->mq_ops) + blk_drain_queue(q); + blk_mq_freeze_queue_wait(q); +} + +void blk_mq_freeze_queue(struct request_queue *q) +{ + /* + * ...just an alias to keep freeze and unfreeze actions balanced + * in the blk_mq_* namespace + */ + blk_freeze_queue(q); +} +EXPORT_SYMBOL_GPL(blk_mq_freeze_queue); + +void blk_mq_unfreeze_queue(struct request_queue *q) +{ + int freeze_depth; + + freeze_depth = atomic_dec_return(&q->mq_freeze_depth); + WARN_ON_ONCE(freeze_depth < 0); + if (!freeze_depth) { + percpu_ref_reinit(&q->q_usage_counter); + wake_up_all(&q->mq_freeze_wq); + } +} +EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue); + +/* + * FIXME: replace the scsi_internal_device_*block_nowait() calls in the + * mpt3sas driver such that this function can be removed. + */ +void blk_mq_quiesce_queue_nowait(struct request_queue *q) +{ + blk_queue_flag_set(QUEUE_FLAG_QUIESCED, q); +} +EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait); + +/** + * blk_mq_quiesce_queue() - wait until all ongoing dispatches have finished + * @q: request queue. + * + * Note: this function does not prevent that the struct request end_io() + * callback function is invoked. Once this function is returned, we make + * sure no dispatch can happen until the queue is unquiesced via + * blk_mq_unquiesce_queue(). + */ +void blk_mq_quiesce_queue(struct request_queue *q) +{ + struct blk_mq_hw_ctx *hctx; + unsigned int i; + bool rcu = false; + + blk_mq_quiesce_queue_nowait(q); + + queue_for_each_hw_ctx(q, hctx, i) { + if (hctx->flags & BLK_MQ_F_BLOCKING) + synchronize_srcu(hctx->srcu); + else + rcu = true; + } + if (rcu) + synchronize_rcu(); +} +EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue); + +/* + * blk_mq_unquiesce_queue() - counterpart of blk_mq_quiesce_queue() + * @q: request queue. + * + * This function recovers queue into the state before quiescing + * which is done by blk_mq_quiesce_queue. + */ +void blk_mq_unquiesce_queue(struct request_queue *q) +{ + blk_queue_flag_clear(QUEUE_FLAG_QUIESCED, q); + + /* dispatch requests which are inserted during quiescing */ + blk_mq_run_hw_queues(q, true); +} +EXPORT_SYMBOL_GPL(blk_mq_unquiesce_queue); + +void blk_mq_wake_waiters(struct request_queue *q) +{ + struct blk_mq_hw_ctx *hctx; + unsigned int i; + + queue_for_each_hw_ctx(q, hctx, i) + if (blk_mq_hw_queue_mapped(hctx)) + blk_mq_tag_wakeup_all(hctx->tags, true); +} + +bool blk_mq_can_queue(struct blk_mq_hw_ctx *hctx) +{ + return blk_mq_has_free_tags(hctx->tags); +} +EXPORT_SYMBOL(blk_mq_can_queue); + +static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data, + unsigned int tag, unsigned int op) +{ + struct blk_mq_tags *tags = blk_mq_tags_from_data(data); + struct request *rq = tags->static_rqs[tag]; + req_flags_t rq_flags = 0; + + if (data->flags & BLK_MQ_REQ_INTERNAL) { + rq->tag = -1; + rq->internal_tag = tag; + } else { + if (data->hctx->flags & BLK_MQ_F_TAG_SHARED) { + rq_flags = RQF_MQ_INFLIGHT; + atomic_inc(&data->hctx->nr_active); + } + rq->tag = tag; + rq->internal_tag = -1; + data->hctx->tags->rqs[rq->tag] = rq; + } + + /* csd/requeue_work/fifo_time is initialized before use */ + rq->q = data->q; + rq->mq_ctx = data->ctx; + rq->rq_flags = rq_flags; + rq->cpu = -1; + rq->cmd_flags = op; + if (data->flags & BLK_MQ_REQ_PREEMPT) + rq->rq_flags |= RQF_PREEMPT; + if (blk_queue_io_stat(data->q)) + rq->rq_flags |= RQF_IO_STAT; + INIT_LIST_HEAD(&rq->queuelist); + INIT_HLIST_NODE(&rq->hash); + RB_CLEAR_NODE(&rq->rb_node); + rq->rq_disk = NULL; + rq->part = NULL; + rq->start_time_ns = ktime_get_ns(); + rq->io_start_time_ns = 0; + rq->nr_phys_segments = 0; +#if defined(CONFIG_BLK_DEV_INTEGRITY) + rq->nr_integrity_segments = 0; +#endif + rq->special = NULL; + /* tag was already set */ + rq->extra_len = 0; + rq->__deadline = 0; + + INIT_LIST_HEAD(&rq->timeout_list); + rq->timeout = 0; + + rq->end_io = NULL; + rq->end_io_data = NULL; + rq->next_rq = NULL; + +#ifdef CONFIG_BLK_CGROUP + rq->rl = NULL; +#endif + + data->ctx->rq_dispatched[op_is_sync(op)]++; + refcount_set(&rq->ref, 1); + return rq; +} + +static struct request *blk_mq_get_request(struct request_queue *q, + struct bio *bio, unsigned int op, + struct blk_mq_alloc_data *data) +{ + struct elevator_queue *e = q->elevator; + struct request *rq; + unsigned int tag; + bool put_ctx_on_error = false; + + blk_queue_enter_live(q); + data->q = q; + if (likely(!data->ctx)) { + data->ctx = blk_mq_get_ctx(q); + put_ctx_on_error = true; + } + if (likely(!data->hctx)) + data->hctx = blk_mq_map_queue(q, data->ctx->cpu); + if (op & REQ_NOWAIT) + data->flags |= BLK_MQ_REQ_NOWAIT; + + if (e) { + data->flags |= BLK_MQ_REQ_INTERNAL; + + /* + * Flush requests are special and go directly to the + * dispatch list. Don't include reserved tags in the + * limiting, as it isn't useful. + */ + if (!op_is_flush(op) && e->type->ops.mq.limit_depth && + !(data->flags & BLK_MQ_REQ_RESERVED)) + e->type->ops.mq.limit_depth(op, data); + } else { + blk_mq_tag_busy(data->hctx); + } + + tag = blk_mq_get_tag(data); + if (tag == BLK_MQ_TAG_FAIL) { + if (put_ctx_on_error) { + blk_mq_put_ctx(data->ctx); + data->ctx = NULL; + } + blk_queue_exit(q); + return NULL; + } + + rq = blk_mq_rq_ctx_init(data, tag, op); + if (!op_is_flush(op)) { + rq->elv.icq = NULL; + if (e && e->type->ops.mq.prepare_request) { + if (e->type->icq_cache && rq_ioc(bio)) + blk_mq_sched_assign_ioc(rq, bio); + + e->type->ops.mq.prepare_request(rq, bio); + rq->rq_flags |= RQF_ELVPRIV; + } + } + data->hctx->queued++; + return rq; +} + +struct request *blk_mq_alloc_request(struct request_queue *q, unsigned int op, + blk_mq_req_flags_t flags) +{ + struct blk_mq_alloc_data alloc_data = { .flags = flags }; + struct request *rq; + int ret; + + ret = blk_queue_enter(q, flags); + if (ret) + return ERR_PTR(ret); + + rq = blk_mq_get_request(q, NULL, op, &alloc_data); + blk_queue_exit(q); + + if (!rq) + return ERR_PTR(-EWOULDBLOCK); + + blk_mq_put_ctx(alloc_data.ctx); + + rq->__data_len = 0; + rq->__sector = (sector_t) -1; + rq->bio = rq->biotail = NULL; + return rq; +} +EXPORT_SYMBOL(blk_mq_alloc_request); + +struct request *blk_mq_alloc_request_hctx(struct request_queue *q, + unsigned int op, blk_mq_req_flags_t flags, unsigned int hctx_idx) +{ + struct blk_mq_alloc_data alloc_data = { .flags = flags }; + struct request *rq; + unsigned int cpu; + int ret; + + /* + * If the tag allocator sleeps we could get an allocation for a + * different hardware context. No need to complicate the low level + * allocator for this for the rare use case of a command tied to + * a specific queue. + */ + if (WARN_ON_ONCE(!(flags & BLK_MQ_REQ_NOWAIT))) + return ERR_PTR(-EINVAL); + + if (hctx_idx >= q->nr_hw_queues) + return ERR_PTR(-EIO); + + ret = blk_queue_enter(q, flags); + if (ret) + return ERR_PTR(ret); + + /* + * Check if the hardware context is actually mapped to anything. + * If not tell the caller that it should skip this queue. + */ + alloc_data.hctx = q->queue_hw_ctx[hctx_idx]; + if (!blk_mq_hw_queue_mapped(alloc_data.hctx)) { + blk_queue_exit(q); + return ERR_PTR(-EXDEV); + } + cpu = cpumask_first_and(alloc_data.hctx->cpumask, cpu_online_mask); + alloc_data.ctx = __blk_mq_get_ctx(q, cpu); + + rq = blk_mq_get_request(q, NULL, op, &alloc_data); + blk_queue_exit(q); + + if (!rq) + return ERR_PTR(-EWOULDBLOCK); + + return rq; +} +EXPORT_SYMBOL_GPL(blk_mq_alloc_request_hctx); + +static void __blk_mq_free_request(struct request *rq) +{ + struct request_queue *q = rq->q; + struct blk_mq_ctx *ctx = rq->mq_ctx; + struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu); + const int sched_tag = rq->internal_tag; + + if (rq->tag != -1) + blk_mq_put_tag(hctx, hctx->tags, ctx, rq->tag); + if (sched_tag != -1) + blk_mq_put_tag(hctx, hctx->sched_tags, ctx, sched_tag); + blk_mq_sched_restart(hctx); + blk_queue_exit(q); +} + +void blk_mq_free_request(struct request *rq) +{ + struct request_queue *q = rq->q; + struct elevator_queue *e = q->elevator; + struct blk_mq_ctx *ctx = rq->mq_ctx; + struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu); + + if (rq->rq_flags & RQF_ELVPRIV) { + if (e && e->type->ops.mq.finish_request) + e->type->ops.mq.finish_request(rq); + if (rq->elv.icq) { + put_io_context(rq->elv.icq->ioc); + rq->elv.icq = NULL; + } + } + + ctx->rq_completed[rq_is_sync(rq)]++; + if (rq->rq_flags & RQF_MQ_INFLIGHT) + atomic_dec(&hctx->nr_active); + + if (unlikely(laptop_mode && !blk_rq_is_passthrough(rq))) + laptop_io_completion(q->backing_dev_info); + + rq_qos_done(q, rq); + + if (blk_rq_rl(rq)) + blk_put_rl(blk_rq_rl(rq)); + + WRITE_ONCE(rq->state, MQ_RQ_IDLE); + if (refcount_dec_and_test(&rq->ref)) + __blk_mq_free_request(rq); +} +EXPORT_SYMBOL_GPL(blk_mq_free_request); + +inline void __blk_mq_end_request(struct request *rq, blk_status_t error) +{ + u64 now = ktime_get_ns(); + + if (rq->rq_flags & RQF_STATS) { + blk_mq_poll_stats_start(rq->q); + blk_stat_add(rq, now); + } + + blk_account_io_done(rq, now); + + if (rq->end_io) { + rq_qos_done(rq->q, rq); + rq->end_io(rq, error); + } else { + if (unlikely(blk_bidi_rq(rq))) + blk_mq_free_request(rq->next_rq); + blk_mq_free_request(rq); + } +} +EXPORT_SYMBOL(__blk_mq_end_request); + +void blk_mq_end_request(struct request *rq, blk_status_t error) +{ + if (blk_update_request(rq, error, blk_rq_bytes(rq))) + BUG(); + __blk_mq_end_request(rq, error); +} +EXPORT_SYMBOL(blk_mq_end_request); + +static void __blk_mq_complete_request_remote(void *data) +{ + struct request *rq = data; + + rq->q->softirq_done_fn(rq); +} + +static void __blk_mq_complete_request(struct request *rq) +{ + struct blk_mq_ctx *ctx = rq->mq_ctx; + bool shared = false; + int cpu; + + if (!blk_mq_mark_complete(rq)) + return; + if (rq->internal_tag != -1) + blk_mq_sched_completed_request(rq); + + if (!test_bit(QUEUE_FLAG_SAME_COMP, &rq->q->queue_flags)) { + rq->q->softirq_done_fn(rq); + return; + } + + cpu = get_cpu(); + if (!test_bit(QUEUE_FLAG_SAME_FORCE, &rq->q->queue_flags)) + shared = cpus_share_cache(cpu, ctx->cpu); + + if (cpu != ctx->cpu && !shared && cpu_online(ctx->cpu)) { + rq->csd.func = __blk_mq_complete_request_remote; + rq->csd.info = rq; + rq->csd.flags = 0; + smp_call_function_single_async(ctx->cpu, &rq->csd); + } else { + rq->q->softirq_done_fn(rq); + } + put_cpu(); +} + +static void hctx_unlock(struct blk_mq_hw_ctx *hctx, int srcu_idx) + __releases(hctx->srcu) +{ + if (!(hctx->flags & BLK_MQ_F_BLOCKING)) + rcu_read_unlock(); + else + srcu_read_unlock(hctx->srcu, srcu_idx); +} + +static void hctx_lock(struct blk_mq_hw_ctx *hctx, int *srcu_idx) + __acquires(hctx->srcu) +{ + if (!(hctx->flags & BLK_MQ_F_BLOCKING)) { + /* shut up gcc false positive */ + *srcu_idx = 0; + rcu_read_lock(); + } else + *srcu_idx = srcu_read_lock(hctx->srcu); +} + +/** + * blk_mq_complete_request - end I/O on a request + * @rq: the request being processed + * + * Description: + * Ends all I/O on a request. It does not handle partial completions. + * The actual completion happens out-of-order, through a IPI handler. + **/ +void blk_mq_complete_request(struct request *rq) +{ + if (unlikely(blk_should_fake_timeout(rq->q))) + return; + __blk_mq_complete_request(rq); +} +EXPORT_SYMBOL(blk_mq_complete_request); + +int blk_mq_request_started(struct request *rq) +{ + return blk_mq_rq_state(rq) != MQ_RQ_IDLE; +} +EXPORT_SYMBOL_GPL(blk_mq_request_started); + +void blk_mq_start_request(struct request *rq) +{ + struct request_queue *q = rq->q; + + blk_mq_sched_started_request(rq); + + trace_block_rq_issue(q, rq); + + if (test_bit(QUEUE_FLAG_STATS, &q->queue_flags)) { + rq->io_start_time_ns = ktime_get_ns(); +#ifdef CONFIG_BLK_DEV_THROTTLING_LOW + rq->throtl_size = blk_rq_sectors(rq); +#endif + rq->rq_flags |= RQF_STATS; + rq_qos_issue(q, rq); + } + + WARN_ON_ONCE(blk_mq_rq_state(rq) != MQ_RQ_IDLE); + + blk_add_timer(rq); + WRITE_ONCE(rq->state, MQ_RQ_IN_FLIGHT); + + if (q->dma_drain_size && blk_rq_bytes(rq)) { + /* + * Make sure space for the drain appears. We know we can do + * this because max_hw_segments has been adjusted to be one + * fewer than the device can handle. + */ + rq->nr_phys_segments++; + } +} +EXPORT_SYMBOL(blk_mq_start_request); + +static void __blk_mq_requeue_request(struct request *rq) +{ + struct request_queue *q = rq->q; + + blk_mq_put_driver_tag(rq); + + trace_block_rq_requeue(q, rq); + rq_qos_requeue(q, rq); + + if (blk_mq_request_started(rq)) { + WRITE_ONCE(rq->state, MQ_RQ_IDLE); + rq->rq_flags &= ~RQF_TIMED_OUT; + if (q->dma_drain_size && blk_rq_bytes(rq)) + rq->nr_phys_segments--; + } +} + +void blk_mq_requeue_request(struct request *rq, bool kick_requeue_list) +{ + __blk_mq_requeue_request(rq); + + /* this request will be re-inserted to io scheduler queue */ + blk_mq_sched_requeue_request(rq); + + BUG_ON(blk_queued_rq(rq)); + blk_mq_add_to_requeue_list(rq, true, kick_requeue_list); +} +EXPORT_SYMBOL(blk_mq_requeue_request); + +static void blk_mq_requeue_work(struct work_struct *work) +{ + struct request_queue *q = + container_of(work, struct request_queue, requeue_work.work); + LIST_HEAD(rq_list); + struct request *rq, *next; + + 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); + 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); +} +EXPORT_SYMBOL(blk_mq_add_to_requeue_list); + +void blk_mq_kick_requeue_list(struct request_queue *q) +{ + kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND, &q->requeue_work, 0); +} +EXPORT_SYMBOL(blk_mq_kick_requeue_list); + +void blk_mq_delay_kick_requeue_list(struct request_queue *q, + unsigned long msecs) +{ + kblockd_mod_delayed_work_on(WORK_CPU_UNBOUND, &q->requeue_work, + msecs_to_jiffies(msecs)); +} +EXPORT_SYMBOL(blk_mq_delay_kick_requeue_list); + +struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag) +{ + if (tag < tags->nr_tags) { + prefetch(tags->rqs[tag]); + return tags->rqs[tag]; + } + + return NULL; +} +EXPORT_SYMBOL(blk_mq_tag_to_rq); + +static void blk_mq_rq_timed_out(struct request *req, bool reserved) +{ + req->rq_flags |= RQF_TIMED_OUT; + if (req->q->mq_ops->timeout) { + enum blk_eh_timer_return ret; + + ret = req->q->mq_ops->timeout(req, reserved); + if (ret == BLK_EH_DONE) + return; + WARN_ON_ONCE(ret != BLK_EH_RESET_TIMER); + } + + blk_add_timer(req); +} + +static bool blk_mq_req_expired(struct request *rq, unsigned long *next) +{ + unsigned long deadline; + + if (blk_mq_rq_state(rq) != MQ_RQ_IN_FLIGHT) + return false; + if (rq->rq_flags & RQF_TIMED_OUT) + return false; + + deadline = blk_rq_deadline(rq); + if (time_after_eq(jiffies, deadline)) + return true; + + if (*next == 0) + *next = deadline; + else if (time_after(*next, deadline)) + *next = deadline; + return false; +} + +static void blk_mq_check_expired(struct blk_mq_hw_ctx *hctx, + struct request *rq, void *priv, bool reserved) +{ + unsigned long *next = priv; + + /* + * Just do a quick check if it is expired before locking the request in + * so we're not unnecessarilly synchronizing across CPUs. + */ + if (!blk_mq_req_expired(rq, next)) + return; + + /* + * We have reason to believe the request may be expired. Take a + * reference on the request to lock this request lifetime into its + * currently allocated context to prevent it from being reallocated in + * the event the completion by-passes this timeout handler. + * + * If the reference was already released, then the driver beat the + * timeout handler to posting a natural completion. + */ + if (!refcount_inc_not_zero(&rq->ref)) + return; + + /* + * The request is now locked and cannot be reallocated underneath the + * timeout handler's processing. Re-verify this exact request is truly + * expired; if it is not expired, then the request was completed and + * reallocated as a new request. + */ + if (blk_mq_req_expired(rq, next)) + blk_mq_rq_timed_out(rq, reserved); + + if (is_flush_rq(rq, hctx)) + rq->end_io(rq, 0); + else if (refcount_dec_and_test(&rq->ref)) + __blk_mq_free_request(rq); +} + +static void blk_mq_timeout_work(struct work_struct *work) +{ + struct request_queue *q = + container_of(work, struct request_queue, timeout_work); + unsigned long next = 0; + struct blk_mq_hw_ctx *hctx; + int i; + + /* A deadlock might occur if a request is stuck requiring a + * timeout at the same time a queue freeze is waiting + * completion, since the timeout code would not be able to + * acquire the queue reference here. + * + * That's why we don't use blk_queue_enter here; instead, we use + * percpu_ref_tryget directly, because we need to be able to + * obtain a reference even in the short window between the queue + * starting to freeze, by dropping the first reference in + * blk_freeze_queue_start, and the moment the last request is + * consumed, marked by the instant q_usage_counter reaches + * zero. + */ + if (!percpu_ref_tryget(&q->q_usage_counter)) + return; + + blk_mq_queue_tag_busy_iter(q, blk_mq_check_expired, &next); + + if (next != 0) { + mod_timer(&q->timeout, next); + } else { + /* + * Request timeouts are handled as a forward rolling timer. If + * we end up here it means that no requests are pending and + * also that no request has been pending for a while. Mark + * each hctx as idle. + */ + queue_for_each_hw_ctx(q, hctx, i) { + /* the hctx may be unmapped, so check it here */ + if (blk_mq_hw_queue_mapped(hctx)) + blk_mq_tag_idle(hctx); + } + } + blk_queue_exit(q); +} + +struct flush_busy_ctx_data { + struct blk_mq_hw_ctx *hctx; + struct list_head *list; +}; + +static bool flush_busy_ctx(struct sbitmap *sb, unsigned int bitnr, void *data) +{ + struct flush_busy_ctx_data *flush_data = data; + struct blk_mq_hw_ctx *hctx = flush_data->hctx; + struct blk_mq_ctx *ctx = hctx->ctxs[bitnr]; + + spin_lock(&ctx->lock); + list_splice_tail_init(&ctx->rq_list, flush_data->list); + sbitmap_clear_bit(sb, bitnr); + spin_unlock(&ctx->lock); + return true; +} + +/* + * Process software queues that have been marked busy, splicing them + * to the for-dispatch + */ +void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list) +{ + struct flush_busy_ctx_data data = { + .hctx = hctx, + .list = list, + }; + + sbitmap_for_each_set(&hctx->ctx_map, flush_busy_ctx, &data); +} +EXPORT_SYMBOL_GPL(blk_mq_flush_busy_ctxs); + +struct dispatch_rq_data { + struct blk_mq_hw_ctx *hctx; + struct request *rq; +}; + +static bool dispatch_rq_from_ctx(struct sbitmap *sb, unsigned int bitnr, + void *data) +{ + struct dispatch_rq_data *dispatch_data = data; + struct blk_mq_hw_ctx *hctx = dispatch_data->hctx; + struct blk_mq_ctx *ctx = hctx->ctxs[bitnr]; + + spin_lock(&ctx->lock); + if (!list_empty(&ctx->rq_list)) { + dispatch_data->rq = list_entry_rq(ctx->rq_list.next); + list_del_init(&dispatch_data->rq->queuelist); + if (list_empty(&ctx->rq_list)) + sbitmap_clear_bit(sb, bitnr); + } + spin_unlock(&ctx->lock); + + return !dispatch_data->rq; +} + +struct request *blk_mq_dequeue_from_ctx(struct blk_mq_hw_ctx *hctx, + struct blk_mq_ctx *start) +{ + unsigned off = start ? start->index_hw : 0; + struct dispatch_rq_data data = { + .hctx = hctx, + .rq = NULL, + }; + + __sbitmap_for_each_set(&hctx->ctx_map, off, + dispatch_rq_from_ctx, &data); + + return data.rq; +} + +static inline unsigned int queued_to_index(unsigned int queued) +{ + if (!queued) + return 0; + + return min(BLK_MQ_MAX_DISPATCH_ORDER - 1, ilog2(queued) + 1); +} + +bool blk_mq_get_driver_tag(struct request *rq) +{ + struct blk_mq_alloc_data data = { + .q = rq->q, + .hctx = blk_mq_map_queue(rq->q, rq->mq_ctx->cpu), + .flags = BLK_MQ_REQ_NOWAIT, + }; + bool shared; + + if (rq->tag != -1) + goto done; + + if (blk_mq_tag_is_reserved(data.hctx->sched_tags, rq->internal_tag)) + data.flags |= BLK_MQ_REQ_RESERVED; + + shared = blk_mq_tag_busy(data.hctx); + rq->tag = blk_mq_get_tag(&data); + if (rq->tag >= 0) { + if (shared) { + rq->rq_flags |= RQF_MQ_INFLIGHT; + atomic_inc(&data.hctx->nr_active); + } + data.hctx->tags->rqs[rq->tag] = rq; + } + +done: + return rq->tag != -1; +} + +static int blk_mq_dispatch_wake(wait_queue_entry_t *wait, unsigned mode, + int flags, void *key) +{ + struct blk_mq_hw_ctx *hctx; + + hctx = container_of(wait, struct blk_mq_hw_ctx, dispatch_wait); + + spin_lock(&hctx->dispatch_wait_lock); + list_del_init(&wait->entry); + spin_unlock(&hctx->dispatch_wait_lock); + + blk_mq_run_hw_queue(hctx, true); + return 1; +} + +/* + * Mark us waiting for a tag. For shared tags, this involves hooking us into + * the tag wakeups. For non-shared tags, we can simply mark us needing a + * restart. For both cases, take care to check the condition again after + * marking us as waiting. + */ +static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx *hctx, + struct request *rq) +{ + struct wait_queue_head *wq; + wait_queue_entry_t *wait; + bool ret; + + if (!(hctx->flags & BLK_MQ_F_TAG_SHARED)) { + if (!test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state)) + set_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state); + + /* + * It's possible that a tag was freed in the window between the + * allocation failure and adding the hardware queue to the wait + * queue. + * + * Don't clear RESTART here, someone else could have set it. + * At most this will cost an extra queue run. + */ + return blk_mq_get_driver_tag(rq); + } + + wait = &hctx->dispatch_wait; + if (!list_empty_careful(&wait->entry)) + return false; + + wq = &bt_wait_ptr(&hctx->tags->bitmap_tags, hctx)->wait; + + spin_lock_irq(&wq->lock); + spin_lock(&hctx->dispatch_wait_lock); + if (!list_empty(&wait->entry)) { + spin_unlock(&hctx->dispatch_wait_lock); + spin_unlock_irq(&wq->lock); + return false; + } + + wait->flags &= ~WQ_FLAG_EXCLUSIVE; + __add_wait_queue(wq, wait); + + /* + * It's possible that a tag was freed in the window between the + * allocation failure and adding the hardware queue to the wait + * queue. + */ + ret = blk_mq_get_driver_tag(rq); + if (!ret) { + spin_unlock(&hctx->dispatch_wait_lock); + spin_unlock_irq(&wq->lock); + return false; + } + + /* + * We got a tag, remove ourselves from the wait queue to ensure + * someone else gets the wakeup. + */ + list_del_init(&wait->entry); + spin_unlock(&hctx->dispatch_wait_lock); + spin_unlock_irq(&wq->lock); + + return true; +} + +#define BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT 8 +#define BLK_MQ_DISPATCH_BUSY_EWMA_FACTOR 4 +/* + * Update dispatch busy with the Exponential Weighted Moving Average(EWMA): + * - EWMA is one simple way to compute running average value + * - weight(7/8 and 1/8) is applied so that it can decrease exponentially + * - take 4 as factor for avoiding to get too small(0) result, and this + * factor doesn't matter because EWMA decreases exponentially + */ +static void blk_mq_update_dispatch_busy(struct blk_mq_hw_ctx *hctx, bool busy) +{ + unsigned int ewma; + + if (hctx->queue->elevator) + return; + + ewma = hctx->dispatch_busy; + + if (!ewma && !busy) + return; + + ewma *= BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT - 1; + if (busy) + ewma += 1 << BLK_MQ_DISPATCH_BUSY_EWMA_FACTOR; + ewma /= BLK_MQ_DISPATCH_BUSY_EWMA_WEIGHT; + + hctx->dispatch_busy = ewma; +} + +#define BLK_MQ_RESOURCE_DELAY 3 /* ms units */ + +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); +} + +/* + * Returns true if we did some work AND can potentially do more. + */ +bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list, + bool got_budget) +{ + struct blk_mq_hw_ctx *hctx; + struct request *rq, *nxt; + bool no_tag = false; + int errors, queued; + blk_status_t ret = BLK_STS_OK; + + if (list_empty(list)) + return false; + + WARN_ON(!list_is_singular(list) && got_budget); + + /* + * Now process all the entries, sending them to the driver. + */ + errors = queued = 0; + do { + struct blk_mq_queue_data bd; + + rq = list_first_entry(list, struct request, queuelist); + + hctx = blk_mq_map_queue(rq->q, rq->mq_ctx->cpu); + if (!got_budget && !blk_mq_get_dispatch_budget(hctx)) + break; + + if (!blk_mq_get_driver_tag(rq)) { + /* + * The initial allocation attempt failed, so we need to + * rerun the hardware queue when a tag is freed. The + * waitqueue takes care of that. If the queue is run + * before we add this entry back on the dispatch list, + * we'll re-run it below. + */ + if (!blk_mq_mark_tag_wait(hctx, rq)) { + blk_mq_put_dispatch_budget(hctx); + /* + * For non-shared tags, the RESTART check + * will suffice. + */ + if (hctx->flags & BLK_MQ_F_TAG_SHARED) + no_tag = true; + break; + } + } + + list_del_init(&rq->queuelist); + + bd.rq = rq; + + /* + * Flag last if we have no more requests, or if we have more + * but can't assign a driver tag to it. + */ + if (list_empty(list)) + bd.last = true; + else { + nxt = list_first_entry(list, struct request, queuelist); + bd.last = !blk_mq_get_driver_tag(nxt); + } + + ret = q->mq_ops->queue_rq(hctx, &bd); + if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE) { + blk_mq_handle_dev_resource(rq, list); + break; + } + + if (unlikely(ret != BLK_STS_OK)) { + errors++; + blk_mq_end_request(rq, BLK_STS_IOERR); + continue; + } + + queued++; + } while (!list_empty(list)); + + hctx->dispatched[queued_to_index(queued)]++; + + /* + * Any items that need requeuing? Stuff them into hctx->dispatch, + * that is where we will continue on next queue run. + */ + if (!list_empty(list)) { + bool needs_restart; + + spin_lock(&hctx->lock); + list_splice_init(list, &hctx->dispatch); + spin_unlock(&hctx->lock); + + /* + * 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. + */ + needs_restart = blk_mq_sched_needs_restart(hctx); + if (!needs_restart || + (no_tag && list_empty_careful(&hctx->dispatch_wait.entry))) + blk_mq_run_hw_queue(hctx, true); + else if (needs_restart && (ret == BLK_STS_RESOURCE)) + blk_mq_delay_run_hw_queue(hctx, BLK_MQ_RESOURCE_DELAY); + + blk_mq_update_dispatch_busy(hctx, true); + return false; + } else + blk_mq_update_dispatch_busy(hctx, false); + + /* + * If the host/device is unable to accept more work, inform the + * caller of that. + */ + if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE) + return false; + + return (queued + errors) != 0; +} + +static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx) +{ + int srcu_idx; + + /* + * We should be running this queue from one of the CPUs that + * are mapped to it. + * + * There are at least two related races now between setting + * hctx->next_cpu from blk_mq_hctx_next_cpu() and running + * __blk_mq_run_hw_queue(): + * + * - hctx->next_cpu is found offline in blk_mq_hctx_next_cpu(), + * but later it becomes online, then this warning is harmless + * at all + * + * - hctx->next_cpu is found online in blk_mq_hctx_next_cpu(), + * but later it becomes offline, then the warning can't be + * triggered, and we depend on blk-mq timeout handler to + * handle dispatched requests to this hctx + */ + if (!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask) && + cpu_online(hctx->next_cpu)) { + printk(KERN_WARNING "run queue from wrong CPU %d, hctx %s\n", + raw_smp_processor_id(), + cpumask_empty(hctx->cpumask) ? "inactive": "active"); + dump_stack(); + } + + /* + * We can't run the queue inline with ints disabled. Ensure that + * we catch bad users of this early. + */ + WARN_ON_ONCE(in_interrupt()); + + might_sleep_if(hctx->flags & BLK_MQ_F_BLOCKING); + + hctx_lock(hctx, &srcu_idx); + blk_mq_sched_dispatch_requests(hctx); + hctx_unlock(hctx, srcu_idx); +} + +static inline int blk_mq_first_mapped_cpu(struct blk_mq_hw_ctx *hctx) +{ + int cpu = cpumask_first_and(hctx->cpumask, cpu_online_mask); + + if (cpu >= nr_cpu_ids) + cpu = cpumask_first(hctx->cpumask); + return cpu; +} + +/* + * It'd be great if the workqueue API had a way to pass + * in a mask and had some smarts for more clever placement. + * For now we just round-robin here, switching for every + * BLK_MQ_CPU_WORK_BATCH queued items. + */ +static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx) +{ + bool tried = false; + int next_cpu = hctx->next_cpu; + + if (hctx->queue->nr_hw_queues == 1) + return WORK_CPU_UNBOUND; + + if (--hctx->next_cpu_batch <= 0) { +select_cpu: + next_cpu = cpumask_next_and(next_cpu, hctx->cpumask, + cpu_online_mask); + if (next_cpu >= nr_cpu_ids) + next_cpu = blk_mq_first_mapped_cpu(hctx); + hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH; + } + + /* + * Do unbound schedule if we can't find a online CPU for this hctx, + * and it should only happen in the path of handling CPU DEAD. + */ + if (!cpu_online(next_cpu)) { + if (!tried) { + tried = true; + goto select_cpu; + } + + /* + * Make sure to re-select CPU next time once after CPUs + * in hctx->cpumask become online again. + */ + hctx->next_cpu = next_cpu; + hctx->next_cpu_batch = 1; + return WORK_CPU_UNBOUND; + } + + hctx->next_cpu = next_cpu; + return next_cpu; +} + +static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async, + unsigned long msecs) +{ + if (unlikely(blk_mq_hctx_stopped(hctx))) + return; + + if (!async && !(hctx->flags & BLK_MQ_F_BLOCKING)) { + int cpu = get_cpu(); + if (cpumask_test_cpu(cpu, hctx->cpumask)) { + __blk_mq_run_hw_queue(hctx); + put_cpu(); + return; + } + + put_cpu(); + } + + kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx), &hctx->run_work, + msecs_to_jiffies(msecs)); +} + +void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs) +{ + __blk_mq_delay_run_hw_queue(hctx, true, msecs); +} +EXPORT_SYMBOL(blk_mq_delay_run_hw_queue); + +bool blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async) +{ + int srcu_idx; + bool need_run; + + /* + * When queue is quiesced, we may be switching io scheduler, or + * updating nr_hw_queues, or other things, and we can't run queue + * any more, even __blk_mq_hctx_has_pending() can't be called safely. + * + * And queue will be rerun in blk_mq_unquiesce_queue() if it is + * quiesced. + */ + hctx_lock(hctx, &srcu_idx); + need_run = !blk_queue_quiesced(hctx->queue) && + blk_mq_hctx_has_pending(hctx); + hctx_unlock(hctx, srcu_idx); + + if (need_run) { + __blk_mq_delay_run_hw_queue(hctx, async, 0); + return true; + } + + return false; +} +EXPORT_SYMBOL(blk_mq_run_hw_queue); + +void blk_mq_run_hw_queues(struct request_queue *q, bool async) +{ + struct blk_mq_hw_ctx *hctx; + int i; + + queue_for_each_hw_ctx(q, hctx, i) { + if (blk_mq_hctx_stopped(hctx)) + continue; + + blk_mq_run_hw_queue(hctx, async); + } +} +EXPORT_SYMBOL(blk_mq_run_hw_queues); + +/** + * blk_mq_queue_stopped() - check whether one or more hctxs have been stopped + * @q: request queue. + * + * The caller is responsible for serializing this function against + * blk_mq_{start,stop}_hw_queue(). + */ +bool blk_mq_queue_stopped(struct request_queue *q) +{ + struct blk_mq_hw_ctx *hctx; + int i; + + queue_for_each_hw_ctx(q, hctx, i) + if (blk_mq_hctx_stopped(hctx)) + return true; + + return false; +} +EXPORT_SYMBOL(blk_mq_queue_stopped); + +/* + * This function is often used for pausing .queue_rq() by driver when + * there isn't enough resource or some conditions aren't satisfied, and + * BLK_STS_RESOURCE is usually returned. + * + * We do not guarantee that dispatch can be drained or blocked + * after blk_mq_stop_hw_queue() returns. Please use + * blk_mq_quiesce_queue() for that requirement. + */ +void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx) +{ + cancel_delayed_work(&hctx->run_work); + + set_bit(BLK_MQ_S_STOPPED, &hctx->state); +} +EXPORT_SYMBOL(blk_mq_stop_hw_queue); + +/* + * This function is often used for pausing .queue_rq() by driver when + * there isn't enough resource or some conditions aren't satisfied, and + * BLK_STS_RESOURCE is usually returned. + * + * We do not guarantee that dispatch can be drained or blocked + * after blk_mq_stop_hw_queues() returns. Please use + * blk_mq_quiesce_queue() for that requirement. + */ +void blk_mq_stop_hw_queues(struct request_queue *q) +{ + struct blk_mq_hw_ctx *hctx; + int i; + + queue_for_each_hw_ctx(q, hctx, i) + blk_mq_stop_hw_queue(hctx); +} +EXPORT_SYMBOL(blk_mq_stop_hw_queues); + +void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx) +{ + clear_bit(BLK_MQ_S_STOPPED, &hctx->state); + + blk_mq_run_hw_queue(hctx, false); +} +EXPORT_SYMBOL(blk_mq_start_hw_queue); + +void blk_mq_start_hw_queues(struct request_queue *q) +{ + struct blk_mq_hw_ctx *hctx; + int i; + + queue_for_each_hw_ctx(q, hctx, i) + blk_mq_start_hw_queue(hctx); +} +EXPORT_SYMBOL(blk_mq_start_hw_queues); + +void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx *hctx, bool async) +{ + if (!blk_mq_hctx_stopped(hctx)) + return; + + clear_bit(BLK_MQ_S_STOPPED, &hctx->state); + blk_mq_run_hw_queue(hctx, async); +} +EXPORT_SYMBOL_GPL(blk_mq_start_stopped_hw_queue); + +void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async) +{ + struct blk_mq_hw_ctx *hctx; + int i; + + queue_for_each_hw_ctx(q, hctx, i) + blk_mq_start_stopped_hw_queue(hctx, async); +} +EXPORT_SYMBOL(blk_mq_start_stopped_hw_queues); + +static void blk_mq_run_work_fn(struct work_struct *work) +{ + struct blk_mq_hw_ctx *hctx; + + hctx = container_of(work, struct blk_mq_hw_ctx, run_work.work); + + /* + * If we are stopped, don't run the queue. + */ + if (test_bit(BLK_MQ_S_STOPPED, &hctx->state)) + return; + + __blk_mq_run_hw_queue(hctx); +} + +static inline void __blk_mq_insert_req_list(struct blk_mq_hw_ctx *hctx, + struct request *rq, + bool at_head) +{ + struct blk_mq_ctx *ctx = rq->mq_ctx; + + lockdep_assert_held(&ctx->lock); + + trace_block_rq_insert(hctx->queue, rq); + + if (at_head) + list_add(&rq->queuelist, &ctx->rq_list); + else + list_add_tail(&rq->queuelist, &ctx->rq_list); +} + +void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq, + bool at_head) +{ + struct blk_mq_ctx *ctx = rq->mq_ctx; + + lockdep_assert_held(&ctx->lock); + + __blk_mq_insert_req_list(hctx, rq, at_head); + blk_mq_hctx_mark_pending(hctx, ctx); +} + +/* + * Should only be used carefully, when the caller knows we want to + * bypass a potential IO scheduler on the target device. + */ +void blk_mq_request_bypass_insert(struct request *rq, bool run_queue) +{ + struct blk_mq_ctx *ctx = rq->mq_ctx; + struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(rq->q, ctx->cpu); + + spin_lock(&hctx->lock); + list_add_tail(&rq->queuelist, &hctx->dispatch); + spin_unlock(&hctx->lock); + + if (run_queue) + blk_mq_run_hw_queue(hctx, false); +} + +void blk_mq_insert_requests(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx, + struct list_head *list) + +{ + struct request *rq; + + /* + * preemption doesn't flush plug list, so it's possible ctx->cpu is + * offline now + */ + list_for_each_entry(rq, list, queuelist) { + BUG_ON(rq->mq_ctx != ctx); + trace_block_rq_insert(hctx->queue, rq); + } + + spin_lock(&ctx->lock); + list_splice_tail_init(list, &ctx->rq_list); + blk_mq_hctx_mark_pending(hctx, ctx); + spin_unlock(&ctx->lock); +} + +static int plug_ctx_cmp(void *priv, struct list_head *a, struct list_head *b) +{ + struct request *rqa = container_of(a, struct request, queuelist); + struct request *rqb = container_of(b, struct request, queuelist); + + return !(rqa->mq_ctx < rqb->mq_ctx || + (rqa->mq_ctx == rqb->mq_ctx && + blk_rq_pos(rqa) < blk_rq_pos(rqb))); +} + +void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule) +{ + struct blk_mq_ctx *this_ctx; + struct request_queue *this_q; + struct request *rq; + LIST_HEAD(list); + LIST_HEAD(ctx_list); + unsigned int depth; + + list_splice_init(&plug->mq_list, &list); + + list_sort(NULL, &list, plug_ctx_cmp); + + this_q = NULL; + this_ctx = NULL; + depth = 0; + + while (!list_empty(&list)) { + rq = list_entry_rq(list.next); + list_del_init(&rq->queuelist); + BUG_ON(!rq->q); + if (rq->mq_ctx != this_ctx) { + if (this_ctx) { + trace_block_unplug(this_q, depth, !from_schedule); + blk_mq_sched_insert_requests(this_q, this_ctx, + &ctx_list, + from_schedule); + } + + this_ctx = rq->mq_ctx; + this_q = rq->q; + depth = 0; + } + + depth++; + list_add_tail(&rq->queuelist, &ctx_list); + } + + /* + * If 'this_ctx' is set, we know we have entries to complete + * on 'ctx_list'. Do those. + */ + if (this_ctx) { + trace_block_unplug(this_q, depth, !from_schedule); + blk_mq_sched_insert_requests(this_q, this_ctx, &ctx_list, + from_schedule); + } +} + +static void blk_mq_bio_to_request(struct request *rq, struct bio *bio) +{ + blk_init_request_from_bio(rq, bio); + + blk_rq_set_rl(rq, blk_get_rl(rq->q, bio)); + + blk_account_io_start(rq, true); +} + +static blk_qc_t request_to_qc_t(struct blk_mq_hw_ctx *hctx, struct request *rq) +{ + if (rq->tag != -1) + return blk_tag_to_qc_t(rq->tag, hctx->queue_num, false); + + return blk_tag_to_qc_t(rq->internal_tag, hctx->queue_num, true); +} + +static blk_status_t __blk_mq_issue_directly(struct blk_mq_hw_ctx *hctx, + struct request *rq, + blk_qc_t *cookie) +{ + struct request_queue *q = rq->q; + struct blk_mq_queue_data bd = { + .rq = rq, + .last = true, + }; + blk_qc_t new_cookie; + blk_status_t ret; + + new_cookie = request_to_qc_t(hctx, rq); + + /* + * For OK queue, we are done. For error, caller may kill it. + * Any other error (busy), just add it to our list as we + * previously would have done. + */ + ret = q->mq_ops->queue_rq(hctx, &bd); + switch (ret) { + case BLK_STS_OK: + blk_mq_update_dispatch_busy(hctx, false); + *cookie = new_cookie; + break; + case BLK_STS_RESOURCE: + case BLK_STS_DEV_RESOURCE: + blk_mq_update_dispatch_busy(hctx, true); + __blk_mq_requeue_request(rq); + break; + default: + blk_mq_update_dispatch_busy(hctx, false); + *cookie = BLK_QC_T_NONE; + break; + } + + return ret; +} + +static blk_status_t __blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx, + struct request *rq, + blk_qc_t *cookie, + bool bypass_insert) +{ + struct request_queue *q = rq->q; + bool run_queue = true; + + /* + * RCU or SRCU read lock is needed before checking quiesced flag. + * + * When queue is stopped or quiesced, ignore 'bypass_insert' from + * blk_mq_request_issue_directly(), and return BLK_STS_OK to caller, + * and avoid driver to try to dispatch again. + */ + if (blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(q)) { + run_queue = false; + bypass_insert = false; + goto insert; + } + + if (q->elevator && !bypass_insert) + goto insert; + + if (!blk_mq_get_dispatch_budget(hctx)) + goto insert; + + if (!blk_mq_get_driver_tag(rq)) { + blk_mq_put_dispatch_budget(hctx); + goto insert; + } + + return __blk_mq_issue_directly(hctx, rq, cookie); +insert: + if (bypass_insert) + return BLK_STS_RESOURCE; + + blk_mq_request_bypass_insert(rq, run_queue); + return BLK_STS_OK; +} + +static void blk_mq_try_issue_directly(struct blk_mq_hw_ctx *hctx, + struct request *rq, blk_qc_t *cookie) +{ + blk_status_t ret; + int srcu_idx; + + might_sleep_if(hctx->flags & BLK_MQ_F_BLOCKING); + + hctx_lock(hctx, &srcu_idx); + + ret = __blk_mq_try_issue_directly(hctx, rq, cookie, false); + if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE) + blk_mq_request_bypass_insert(rq, true); + else if (ret != BLK_STS_OK) + blk_mq_end_request(rq, ret); + + hctx_unlock(hctx, srcu_idx); +} + +blk_status_t blk_mq_request_issue_directly(struct request *rq) +{ + blk_status_t ret; + int srcu_idx; + blk_qc_t unused_cookie; + struct blk_mq_ctx *ctx = rq->mq_ctx; + struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(rq->q, ctx->cpu); + + hctx_lock(hctx, &srcu_idx); + ret = __blk_mq_try_issue_directly(hctx, rq, &unused_cookie, true); + hctx_unlock(hctx, srcu_idx); + + return ret; +} + +void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx *hctx, + struct list_head *list) +{ + while (!list_empty(list)) { + blk_status_t ret; + struct request *rq = list_first_entry(list, struct request, + queuelist); + + list_del_init(&rq->queuelist); + ret = blk_mq_request_issue_directly(rq); + if (ret != BLK_STS_OK) { + if (ret == BLK_STS_RESOURCE || + ret == BLK_STS_DEV_RESOURCE) { + blk_mq_request_bypass_insert(rq, + list_empty(list)); + break; + } + blk_mq_end_request(rq, ret); + } + } +} + +static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio) +{ + const int is_sync = op_is_sync(bio->bi_opf); + const int is_flush_fua = op_is_flush(bio->bi_opf); + struct blk_mq_alloc_data data = { .flags = 0 }; + struct request *rq; + unsigned int request_count = 0; + struct blk_plug *plug; + struct request *same_queue_rq = NULL; + blk_qc_t cookie; + + blk_queue_bounce(q, &bio); + + blk_queue_split(q, &bio); + + if (!bio_integrity_prep(bio)) + return BLK_QC_T_NONE; + + if (!is_flush_fua && !blk_queue_nomerges(q) && + blk_attempt_plug_merge(q, bio, &request_count, &same_queue_rq)) + return BLK_QC_T_NONE; + + if (blk_mq_sched_bio_merge(q, bio)) + return BLK_QC_T_NONE; + + rq_qos_throttle(q, bio, NULL); + + trace_block_getrq(q, bio, bio->bi_opf); + + rq = blk_mq_get_request(q, bio, bio->bi_opf, &data); + if (unlikely(!rq)) { + rq_qos_cleanup(q, bio); + if (bio->bi_opf & REQ_NOWAIT) + bio_wouldblock_error(bio); + return BLK_QC_T_NONE; + } + + rq_qos_track(q, rq, bio); + + cookie = request_to_qc_t(data.hctx, rq); + + plug = current->plug; + if (unlikely(is_flush_fua)) { + blk_mq_put_ctx(data.ctx); + blk_mq_bio_to_request(rq, bio); + + /* bypass scheduler for flush rq */ + blk_insert_flush(rq); + blk_mq_run_hw_queue(data.hctx, true); + } else if (plug && q->nr_hw_queues == 1) { + struct request *last = NULL; + + blk_mq_put_ctx(data.ctx); + blk_mq_bio_to_request(rq, bio); + + /* + * @request_count may become stale because of schedule + * out, so check the list again. + */ + if (list_empty(&plug->mq_list)) + request_count = 0; + else if (blk_queue_nomerges(q)) + request_count = blk_plug_queued_count(q); + + if (!request_count) + trace_block_plug(q); + else + last = list_entry_rq(plug->mq_list.prev); + + if (request_count >= BLK_MAX_REQUEST_COUNT || (last && + blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) { + blk_flush_plug_list(plug, false); + trace_block_plug(q); + } + + list_add_tail(&rq->queuelist, &plug->mq_list); + } else if (plug && !blk_queue_nomerges(q)) { + blk_mq_bio_to_request(rq, bio); + + /* + * We do limited plugging. If the bio can be merged, do that. + * Otherwise the existing request in the plug list will be + * issued. So the plug list will have one request at most + * The plug list might get flushed before this. If that happens, + * the plug list is empty, and same_queue_rq is invalid. + */ + if (list_empty(&plug->mq_list)) + same_queue_rq = NULL; + if (same_queue_rq) + list_del_init(&same_queue_rq->queuelist); + list_add_tail(&rq->queuelist, &plug->mq_list); + + blk_mq_put_ctx(data.ctx); + + if (same_queue_rq) { + data.hctx = blk_mq_map_queue(q, + same_queue_rq->mq_ctx->cpu); + blk_mq_try_issue_directly(data.hctx, same_queue_rq, + &cookie); + } + } else if ((q->nr_hw_queues > 1 && is_sync) || (!q->elevator && + !data.hctx->dispatch_busy)) { + blk_mq_put_ctx(data.ctx); + blk_mq_bio_to_request(rq, bio); + blk_mq_try_issue_directly(data.hctx, rq, &cookie); + } else { + blk_mq_put_ctx(data.ctx); + blk_mq_bio_to_request(rq, bio); + blk_mq_sched_insert_request(rq, false, true, true); + } + + return cookie; +} + +void blk_mq_free_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags, + unsigned int hctx_idx) +{ + struct page *page; + + if (tags->rqs && set->ops->exit_request) { + int i; + + for (i = 0; i < tags->nr_tags; i++) { + struct request *rq = tags->static_rqs[i]; + + if (!rq) + continue; + set->ops->exit_request(set, rq, hctx_idx); + tags->static_rqs[i] = NULL; + } + } + + while (!list_empty(&tags->page_list)) { + page = list_first_entry(&tags->page_list, struct page, lru); + list_del_init(&page->lru); + /* + * Remove kmemleak object previously allocated in + * blk_mq_init_rq_map(). + */ + kmemleak_free(page_address(page)); + __free_pages(page, page->private); + } +} + +void blk_mq_free_rq_map(struct blk_mq_tags *tags) +{ + kfree(tags->rqs); + tags->rqs = NULL; + kfree(tags->static_rqs); + tags->static_rqs = NULL; + + blk_mq_free_tags(tags); +} + +struct blk_mq_tags *blk_mq_alloc_rq_map(struct blk_mq_tag_set *set, + unsigned int hctx_idx, + unsigned int nr_tags, + unsigned int reserved_tags) +{ + struct blk_mq_tags *tags; + int node; + + node = blk_mq_hw_queue_to_node(set->mq_map, hctx_idx); + if (node == NUMA_NO_NODE) + node = set->numa_node; + + tags = blk_mq_init_tags(nr_tags, reserved_tags, node, + BLK_MQ_FLAG_TO_ALLOC_POLICY(set->flags)); + if (!tags) + return NULL; + + tags->rqs = kcalloc_node(nr_tags, sizeof(struct request *), + GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY, + node); + if (!tags->rqs) { + blk_mq_free_tags(tags); + return NULL; + } + + tags->static_rqs = kcalloc_node(nr_tags, sizeof(struct request *), + GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY, + node); + if (!tags->static_rqs) { + kfree(tags->rqs); + blk_mq_free_tags(tags); + return NULL; + } + + return tags; +} + +static size_t order_to_size(unsigned int order) +{ + return (size_t)PAGE_SIZE << order; +} + +static int blk_mq_init_request(struct blk_mq_tag_set *set, struct request *rq, + unsigned int hctx_idx, int node) +{ + int ret; + + if (set->ops->init_request) { + ret = set->ops->init_request(set, rq, hctx_idx, node); + if (ret) + return ret; + } + + WRITE_ONCE(rq->state, MQ_RQ_IDLE); + return 0; +} + +int blk_mq_alloc_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags, + unsigned int hctx_idx, unsigned int depth) +{ + unsigned int i, j, entries_per_page, max_order = 4; + size_t rq_size, left; + int node; + + node = blk_mq_hw_queue_to_node(set->mq_map, hctx_idx); + if (node == NUMA_NO_NODE) + node = set->numa_node; + + INIT_LIST_HEAD(&tags->page_list); + + /* + * rq_size is the size of the request plus driver payload, rounded + * to the cacheline size + */ + rq_size = round_up(sizeof(struct request) + set->cmd_size, + cache_line_size()); + left = rq_size * depth; + + for (i = 0; i < depth; ) { + int this_order = max_order; + struct page *page; + int to_do; + void *p; + + while (this_order && left < order_to_size(this_order - 1)) + this_order--; + + do { + page = alloc_pages_node(node, + GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY | __GFP_ZERO, + this_order); + if (page) + break; + if (!this_order--) + break; + if (order_to_size(this_order) < rq_size) + break; + } while (1); + + if (!page) + goto fail; + + page->private = this_order; + list_add_tail(&page->lru, &tags->page_list); + + p = page_address(page); + /* + * Allow kmemleak to scan these pages as they contain pointers + * to additional allocations like via ops->init_request(). + */ + kmemleak_alloc(p, order_to_size(this_order), 1, GFP_NOIO); + entries_per_page = order_to_size(this_order) / rq_size; + to_do = min(entries_per_page, depth - i); + left -= to_do * rq_size; + for (j = 0; j < to_do; j++) { + struct request *rq = p; + + tags->static_rqs[i] = rq; + if (blk_mq_init_request(set, rq, hctx_idx, node)) { + tags->static_rqs[i] = NULL; + goto fail; + } + + p += rq_size; + i++; + } + } + return 0; + +fail: + blk_mq_free_rqs(set, tags, hctx_idx); + return -ENOMEM; +} + +/* + * 'cpu' is going away. splice any existing rq_list entries from this + * software queue to the hw queue dispatch list, and ensure that it + * gets run. + */ +static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node) +{ + struct blk_mq_hw_ctx *hctx; + struct blk_mq_ctx *ctx; + LIST_HEAD(tmp); + + hctx = hlist_entry_safe(node, struct blk_mq_hw_ctx, cpuhp_dead); + ctx = __blk_mq_get_ctx(hctx->queue, cpu); + + spin_lock(&ctx->lock); + if (!list_empty(&ctx->rq_list)) { + list_splice_init(&ctx->rq_list, &tmp); + blk_mq_hctx_clear_pending(hctx, ctx); + } + spin_unlock(&ctx->lock); + + if (list_empty(&tmp)) + return 0; + + spin_lock(&hctx->lock); + list_splice_tail_init(&tmp, &hctx->dispatch); + spin_unlock(&hctx->lock); + + blk_mq_run_hw_queue(hctx, true); + return 0; +} + +static void blk_mq_remove_cpuhp(struct blk_mq_hw_ctx *hctx) +{ + cpuhp_state_remove_instance_nocalls(CPUHP_BLK_MQ_DEAD, + &hctx->cpuhp_dead); +} + +/* hctx->ctxs will be freed in queue's release handler */ +static void blk_mq_exit_hctx(struct request_queue *q, + struct blk_mq_tag_set *set, + struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx) +{ + blk_mq_debugfs_unregister_hctx(hctx); + + if (blk_mq_hw_queue_mapped(hctx)) + blk_mq_tag_idle(hctx); + + if (set->ops->exit_request) + set->ops->exit_request(set, hctx->fq->flush_rq, hctx_idx); + + if (set->ops->exit_hctx) + set->ops->exit_hctx(hctx, hctx_idx); + + blk_mq_remove_cpuhp(hctx); +} + +static void blk_mq_exit_hw_queues(struct request_queue *q, + struct blk_mq_tag_set *set, int nr_queue) +{ + struct blk_mq_hw_ctx *hctx; + unsigned int i; + + queue_for_each_hw_ctx(q, hctx, i) { + if (i == nr_queue) + break; + blk_mq_exit_hctx(q, set, hctx, i); + } +} + +static int blk_mq_init_hctx(struct request_queue *q, + struct blk_mq_tag_set *set, + struct blk_mq_hw_ctx *hctx, unsigned hctx_idx) +{ + int node; + + node = hctx->numa_node; + if (node == NUMA_NO_NODE) + node = hctx->numa_node = set->numa_node; + + INIT_DELAYED_WORK(&hctx->run_work, blk_mq_run_work_fn); + spin_lock_init(&hctx->lock); + INIT_LIST_HEAD(&hctx->dispatch); + hctx->queue = q; + hctx->flags = set->flags & ~BLK_MQ_F_TAG_SHARED; + + cpuhp_state_add_instance_nocalls(CPUHP_BLK_MQ_DEAD, &hctx->cpuhp_dead); + + hctx->tags = set->tags[hctx_idx]; + + /* + * Allocate space for all possible cpus to avoid allocation at + * runtime + */ + hctx->ctxs = kmalloc_array_node(nr_cpu_ids, sizeof(void *), + GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY, node); + if (!hctx->ctxs) + goto unregister_cpu_notifier; + + if (sbitmap_init_node(&hctx->ctx_map, nr_cpu_ids, ilog2(8), + GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY, node)) + goto free_ctxs; + + hctx->nr_ctx = 0; + + spin_lock_init(&hctx->dispatch_wait_lock); + init_waitqueue_func_entry(&hctx->dispatch_wait, blk_mq_dispatch_wake); + INIT_LIST_HEAD(&hctx->dispatch_wait.entry); + + if (set->ops->init_hctx && + set->ops->init_hctx(hctx, set->driver_data, hctx_idx)) + goto free_bitmap; + + hctx->fq = blk_alloc_flush_queue(q, hctx->numa_node, set->cmd_size, + GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY); + if (!hctx->fq) + goto exit_hctx; + + if (blk_mq_init_request(set, hctx->fq->flush_rq, hctx_idx, node)) + goto free_fq; + + if (hctx->flags & BLK_MQ_F_BLOCKING) + init_srcu_struct(hctx->srcu); + + blk_mq_debugfs_register_hctx(q, hctx); + + return 0; + + free_fq: + blk_free_flush_queue(hctx->fq); + exit_hctx: + if (set->ops->exit_hctx) + set->ops->exit_hctx(hctx, hctx_idx); + free_bitmap: + sbitmap_free(&hctx->ctx_map); + free_ctxs: + kfree(hctx->ctxs); + unregister_cpu_notifier: + blk_mq_remove_cpuhp(hctx); + return -1; +} + +static void blk_mq_init_cpu_queues(struct request_queue *q, + unsigned int nr_hw_queues) +{ + unsigned int i; + + for_each_possible_cpu(i) { + struct blk_mq_ctx *__ctx = per_cpu_ptr(q->queue_ctx, i); + struct blk_mq_hw_ctx *hctx; + + __ctx->cpu = i; + spin_lock_init(&__ctx->lock); + INIT_LIST_HEAD(&__ctx->rq_list); + __ctx->queue = q; + + /* + * Set local node, IFF we have more than one hw queue. If + * not, we remain on the home node of the device + */ + hctx = blk_mq_map_queue(q, i); + if (nr_hw_queues > 1 && hctx->numa_node == NUMA_NO_NODE) + hctx->numa_node = local_memory_node(cpu_to_node(i)); + } +} + +static bool __blk_mq_alloc_rq_map(struct blk_mq_tag_set *set, int hctx_idx) +{ + int ret = 0; + + set->tags[hctx_idx] = blk_mq_alloc_rq_map(set, hctx_idx, + set->queue_depth, set->reserved_tags); + if (!set->tags[hctx_idx]) + return false; + + ret = blk_mq_alloc_rqs(set, set->tags[hctx_idx], hctx_idx, + set->queue_depth); + if (!ret) + return true; + + blk_mq_free_rq_map(set->tags[hctx_idx]); + set->tags[hctx_idx] = NULL; + return false; +} + +static void blk_mq_free_map_and_requests(struct blk_mq_tag_set *set, + unsigned int hctx_idx) +{ + if (set->tags[hctx_idx]) { + blk_mq_free_rqs(set, set->tags[hctx_idx], hctx_idx); + blk_mq_free_rq_map(set->tags[hctx_idx]); + set->tags[hctx_idx] = NULL; + } +} + +static void blk_mq_map_swqueue(struct request_queue *q) +{ + unsigned int i, hctx_idx; + 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) { + hctx_idx = q->mq_map[i]; + /* unmapped hw queue can be remapped after CPU topo changed */ + if (!set->tags[hctx_idx] && + !__blk_mq_alloc_rq_map(set, hctx_idx)) { + /* + * If tags initialization fail for some hctx, + * that hctx won't be brought online. In this + * case, remap the current ctx to hctx[0] which + * is guaranteed to always have tags allocated + */ + q->mq_map[i] = 0; + } + + ctx = per_cpu_ptr(q->queue_ctx, i); + hctx = blk_mq_map_queue(q, i); + + cpumask_set_cpu(i, hctx->cpumask); + ctx->index_hw = hctx->nr_ctx; + hctx->ctxs[hctx->nr_ctx++] = ctx; + } + + queue_for_each_hw_ctx(q, hctx, i) { + /* + * If no software queues are mapped to this hardware queue, + * disable it and free the request entries. + */ + if (!hctx->nr_ctx) { + /* Never unmap queue 0. We need it as a + * fallback in case of a new remap fails + * allocation + */ + if (i && set->tags[i]) + blk_mq_free_map_and_requests(set, i); + + hctx->tags = NULL; + continue; + } + + hctx->tags = set->tags[i]; + WARN_ON(!hctx->tags); + + /* + * Set the map size to the number of mapped software queues. + * This is more accurate and more efficient than looping + * over all possibly mapped software queues. + */ + sbitmap_resize(&hctx->ctx_map, hctx->nr_ctx); + + /* + * Initialize batch roundrobin counts + */ + hctx->next_cpu = blk_mq_first_mapped_cpu(hctx); + hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH; + } +} + +/* + * Caller needs to ensure that we're either frozen/quiesced, or that + * the queue isn't live yet. + */ +static void queue_set_hctx_shared(struct request_queue *q, bool shared) +{ + struct blk_mq_hw_ctx *hctx; + int i; + + queue_for_each_hw_ctx(q, hctx, i) { + if (shared) + hctx->flags |= BLK_MQ_F_TAG_SHARED; + else + hctx->flags &= ~BLK_MQ_F_TAG_SHARED; + } +} + +static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set *set, + bool shared) +{ + struct request_queue *q; + + lockdep_assert_held(&set->tag_list_lock); + + list_for_each_entry(q, &set->tag_list, tag_set_list) { + blk_mq_freeze_queue(q); + queue_set_hctx_shared(q, shared); + blk_mq_unfreeze_queue(q); + } +} + +static void blk_mq_del_queue_tag_set(struct request_queue *q) +{ + struct blk_mq_tag_set *set = q->tag_set; + + mutex_lock(&set->tag_list_lock); + list_del_rcu(&q->tag_set_list); + if (list_is_singular(&set->tag_list)) { + /* just transitioned to unshared */ + set->flags &= ~BLK_MQ_F_TAG_SHARED; + /* update existing queue */ + blk_mq_update_tag_set_depth(set, false); + } + mutex_unlock(&set->tag_list_lock); + INIT_LIST_HEAD(&q->tag_set_list); +} + +static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set, + struct request_queue *q) +{ + q->tag_set = set; + + mutex_lock(&set->tag_list_lock); + + /* + * Check to see if we're transitioning to shared (from 1 to 2 queues). + */ + if (!list_empty(&set->tag_list) && + !(set->flags & BLK_MQ_F_TAG_SHARED)) { + set->flags |= BLK_MQ_F_TAG_SHARED; + /* update existing queue */ + blk_mq_update_tag_set_depth(set, true); + } + if (set->flags & BLK_MQ_F_TAG_SHARED) + queue_set_hctx_shared(q, true); + list_add_tail_rcu(&q->tag_set_list, &set->tag_list); + + mutex_unlock(&set->tag_list_lock); +} + +/* + * It is the actual release handler for mq, but we do it from + * request queue's release handler for avoiding use-after-free + * and headache because q->mq_kobj shouldn't have been introduced, + * but we can't group ctx/kctx kobj without it. + */ +void blk_mq_release(struct request_queue *q) +{ + struct blk_mq_hw_ctx *hctx; + unsigned int i; + + /* hctx kobj stays in hctx */ + queue_for_each_hw_ctx(q, hctx, i) { + if (!hctx) + continue; + kobject_put(&hctx->kobj); + } + + q->mq_map = NULL; + + kfree(q->queue_hw_ctx); + + /* + * release .mq_kobj and sw queue's kobject now because + * both share lifetime with request queue. + */ + blk_mq_sysfs_deinit(q); + + free_percpu(q->queue_ctx); +} + +struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set) +{ + struct request_queue *uninit_q, *q; + + uninit_q = blk_alloc_queue_node(GFP_KERNEL, set->numa_node, NULL); + if (!uninit_q) + return ERR_PTR(-ENOMEM); + + q = blk_mq_init_allocated_queue(set, uninit_q); + if (IS_ERR(q)) + blk_cleanup_queue(uninit_q); + + return q; +} +EXPORT_SYMBOL(blk_mq_init_queue); + +static int blk_mq_hw_ctx_size(struct blk_mq_tag_set *tag_set) +{ + int hw_ctx_size = sizeof(struct blk_mq_hw_ctx); + + BUILD_BUG_ON(ALIGN(offsetof(struct blk_mq_hw_ctx, srcu), + __alignof__(struct blk_mq_hw_ctx)) != + sizeof(struct blk_mq_hw_ctx)); + + if (tag_set->flags & BLK_MQ_F_BLOCKING) + hw_ctx_size += sizeof(struct srcu_struct); + + return hw_ctx_size; +} + +static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set, + struct request_queue *q) +{ + int i, j; + struct blk_mq_hw_ctx **hctxs = q->queue_hw_ctx; + + blk_mq_sysfs_unregister(q); + + /* protect against switching io scheduler */ + mutex_lock(&q->sysfs_lock); + for (i = 0; i < set->nr_hw_queues; i++) { + int node; + + if (hctxs[i]) + continue; + + node = blk_mq_hw_queue_to_node(q->mq_map, i); + hctxs[i] = kzalloc_node(blk_mq_hw_ctx_size(set), + GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY, + node); + if (!hctxs[i]) + break; + + if (!zalloc_cpumask_var_node(&hctxs[i]->cpumask, + GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY, + node)) { + kfree(hctxs[i]); + hctxs[i] = NULL; + break; + } + + atomic_set(&hctxs[i]->nr_active, 0); + hctxs[i]->numa_node = node; + hctxs[i]->queue_num = i; + + if (blk_mq_init_hctx(q, set, hctxs[i], i)) { + free_cpumask_var(hctxs[i]->cpumask); + kfree(hctxs[i]); + hctxs[i] = NULL; + break; + } + blk_mq_hctx_kobj_init(hctxs[i]); + } + for (j = i; j < q->nr_hw_queues; j++) { + struct blk_mq_hw_ctx *hctx = hctxs[j]; + + if (hctx) { + if (hctx->tags) + blk_mq_free_map_and_requests(set, j); + blk_mq_exit_hctx(q, set, hctx, j); + kobject_put(&hctx->kobj); + hctxs[j] = NULL; + + } + } + q->nr_hw_queues = i; + mutex_unlock(&q->sysfs_lock); + blk_mq_sysfs_register(q); +} + +struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set, + struct request_queue *q) +{ + /* mark the queue as mq asap */ + q->mq_ops = set->ops; + + q->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; + + q->queue_ctx = alloc_percpu(struct blk_mq_ctx); + if (!q->queue_ctx) + goto err_exit; + + /* init q->mq_kobj and sw queues' kobjects */ + blk_mq_sysfs_init(q); + + q->queue_hw_ctx = kcalloc_node(nr_cpu_ids, sizeof(*(q->queue_hw_ctx)), + GFP_KERNEL, set->numa_node); + if (!q->queue_hw_ctx) + goto err_percpu; + + q->mq_map = set->mq_map; + + blk_mq_realloc_hw_ctxs(set, q); + if (!q->nr_hw_queues) + goto err_hctxs; + + INIT_WORK(&q->timeout_work, blk_mq_timeout_work); + blk_queue_rq_timeout(q, set->timeout ? set->timeout : 30 * HZ); + + q->nr_queues = nr_cpu_ids; + + q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT; + + if (!(set->flags & BLK_MQ_F_SG_MERGE)) + queue_flag_set_unlocked(QUEUE_FLAG_NO_SG_MERGE, q); + + q->sg_reserved_size = INT_MAX; + + INIT_DELAYED_WORK(&q->requeue_work, blk_mq_requeue_work); + INIT_LIST_HEAD(&q->requeue_list); + spin_lock_init(&q->requeue_lock); + + blk_queue_make_request(q, blk_mq_make_request); + if (q->mq_ops->poll) + q->poll_fn = blk_mq_poll; + + /* + * Do this after blk_queue_make_request() overrides it... + */ + q->nr_requests = set->queue_depth; + + /* + * Default to classic polling + */ + q->poll_nsec = -1; + + if (set->ops->complete) + blk_queue_softirq_done(q, set->ops->complete); + + blk_mq_init_cpu_queues(q, set->nr_hw_queues); + blk_mq_add_queue_tag_set(set, q); + blk_mq_map_swqueue(q); + + if (!(set->flags & BLK_MQ_F_NO_SCHED)) { + int ret; + + ret = elevator_init_mq(q); + if (ret) + return ERR_PTR(ret); + } + + return q; + +err_hctxs: + kfree(q->queue_hw_ctx); +err_percpu: + free_percpu(q->queue_ctx); +err_exit: + q->mq_ops = NULL; + return ERR_PTR(-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); +} + +/* Basically redo blk_mq_init_queue with queue frozen */ +static void blk_mq_queue_reinit(struct request_queue *q) +{ + WARN_ON_ONCE(!atomic_read(&q->mq_freeze_depth)); + + blk_mq_debugfs_unregister_hctxs(q); + blk_mq_sysfs_unregister(q); + + /* + * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe + * we should change hctx numa_node according to the new topology (this + * involves freeing and re-allocating memory, worth doing?) + */ + blk_mq_map_swqueue(q); + + blk_mq_sysfs_register(q); + blk_mq_debugfs_register_hctxs(q); +} + +static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set) +{ + int i; + + for (i = 0; i < set->nr_hw_queues; i++) + if (!__blk_mq_alloc_rq_map(set, i)) + goto out_unwind; + + return 0; + +out_unwind: + while (--i >= 0) + blk_mq_free_rq_map(set->tags[i]); + + return -ENOMEM; +} + +/* + * Allocate the request maps associated with this tag_set. Note that this + * may reduce the depth asked for, if memory is tight. set->queue_depth + * will be updated to reflect the allocated depth. + */ +static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set) +{ + unsigned int depth; + int err; + + depth = set->queue_depth; + do { + err = __blk_mq_alloc_rq_maps(set); + if (!err) + break; + + set->queue_depth >>= 1; + if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN) { + err = -ENOMEM; + break; + } + } while (set->queue_depth); + + if (!set->queue_depth || err) { + pr_err("blk-mq: failed to allocate request map\n"); + return -ENOMEM; + } + + if (depth != set->queue_depth) + pr_info("blk-mq: reduced tag depth (%u -> %u)\n", + depth, set->queue_depth); + + return 0; +} + +static int blk_mq_update_queue_map(struct blk_mq_tag_set *set) +{ + if (set->ops->map_queues) { + /* + * 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->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. + */ + blk_mq_clear_mq_map(set); + + return set->ops->map_queues(set); + } else + return blk_mq_map_queues(set); +} + +/* + * 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 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 a crashdump is active, then we are potentially in a very + * memory constrained environment. Limit us to 1 queue and + * 64 tags to prevent using too much memory. + */ + if (is_kdump_kernel()) { + set->nr_hw_queues = 1; + set->queue_depth = min(64U, set->queue_depth); + } + /* + * There is no use for more h/w queues than cpus. + */ + if (set->nr_hw_queues > nr_cpu_ids) + set->nr_hw_queues = nr_cpu_ids; + + set->tags = kcalloc_node(nr_cpu_ids, sizeof(struct blk_mq_tags *), + GFP_KERNEL, set->numa_node); + if (!set->tags) + return -ENOMEM; + + ret = -ENOMEM; + set->mq_map = kcalloc_node(nr_cpu_ids, sizeof(*set->mq_map), + GFP_KERNEL, set->numa_node); + if (!set->mq_map) + goto out_free_tags; + + ret = blk_mq_update_queue_map(set); + if (ret) + goto out_free_mq_map; + + ret = blk_mq_alloc_rq_maps(set); + if (ret) + goto out_free_mq_map; + + mutex_init(&set->tag_list_lock); + INIT_LIST_HEAD(&set->tag_list); + + return 0; + +out_free_mq_map: + kfree(set->mq_map); + set->mq_map = NULL; +out_free_tags: + kfree(set->tags); + set->tags = NULL; + return ret; +} +EXPORT_SYMBOL(blk_mq_alloc_tag_set); + +void blk_mq_free_tag_set(struct blk_mq_tag_set *set) +{ + int i; + + for (i = 0; i < nr_cpu_ids; i++) + blk_mq_free_map_and_requests(set, i); + + kfree(set->mq_map); + set->mq_map = NULL; + + kfree(set->tags); + set->tags = NULL; +} +EXPORT_SYMBOL(blk_mq_free_tag_set); + +int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr) +{ + struct blk_mq_tag_set *set = q->tag_set; + struct blk_mq_hw_ctx *hctx; + int i, ret; + + if (!set) + return -EINVAL; + + blk_mq_freeze_queue(q); + blk_mq_quiesce_queue(q); + + ret = 0; + queue_for_each_hw_ctx(q, hctx, i) { + if (!hctx->tags) + continue; + /* + * If we're using an MQ scheduler, just update the scheduler + * queue depth. This is similar to what the old code would do. + */ + if (!hctx->sched_tags) { + ret = blk_mq_tag_update_depth(hctx, &hctx->tags, nr, + false); + } else { + ret = blk_mq_tag_update_depth(hctx, &hctx->sched_tags, + nr, true); + } + if (ret) + break; + if (q->elevator && q->elevator->type->ops.mq.depth_updated) + q->elevator->type->ops.mq.depth_updated(hctx); + } + + if (!ret) + q->nr_requests = nr; + + blk_mq_unquiesce_queue(q); + blk_mq_unfreeze_queue(q); + + return ret; +} + +/* + * request_queue and elevator_type pair. + * It is just used by __blk_mq_update_nr_hw_queues to cache + * the elevator_type associated with a request_queue. + */ +struct blk_mq_qe_pair { + struct list_head node; + struct request_queue *q; + struct elevator_type *type; +}; + +/* + * Cache the elevator_type in qe pair list and switch the + * io scheduler to 'none' + */ +static bool blk_mq_elv_switch_none(struct list_head *head, + struct request_queue *q) +{ + struct blk_mq_qe_pair *qe; + + if (!q->elevator) + return true; + + qe = kmalloc(sizeof(*qe), GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY); + if (!qe) + return false; + + INIT_LIST_HEAD(&qe->node); + qe->q = q; + qe->type = q->elevator->type; + list_add(&qe->node, head); + + mutex_lock(&q->sysfs_lock); + /* + * After elevator_switch_mq, the previous elevator_queue will be + * released by elevator_release. The reference of the io scheduler + * module get by elevator_get will also be put. So we need to get + * a reference of the io scheduler module here to prevent it to be + * removed. + */ + __module_get(qe->type->elevator_owner); + elevator_switch_mq(q, NULL); + mutex_unlock(&q->sysfs_lock); + + return true; +} + +static void blk_mq_elv_switch_back(struct list_head *head, + struct request_queue *q) +{ + struct blk_mq_qe_pair *qe; + struct elevator_type *t = NULL; + + list_for_each_entry(qe, head, node) + if (qe->q == q) { + t = qe->type; + break; + } + + if (!t) + return; + + list_del(&qe->node); + kfree(qe); + + mutex_lock(&q->sysfs_lock); + elevator_switch_mq(q, t); + mutex_unlock(&q->sysfs_lock); +} + +static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, + int nr_hw_queues) +{ + struct request_queue *q; + LIST_HEAD(head); + + lockdep_assert_held(&set->tag_list_lock); + + if (nr_hw_queues > nr_cpu_ids) + nr_hw_queues = nr_cpu_ids; + if (nr_hw_queues < 1 || nr_hw_queues == set->nr_hw_queues) + return; + + list_for_each_entry(q, &set->tag_list, tag_set_list) + blk_mq_freeze_queue(q); + /* + * Sync with blk_mq_queue_tag_busy_iter. + */ + synchronize_rcu(); + /* + * Switch IO scheduler to 'none', cleaning up the data associated + * with the previous scheduler. We will switch back once we are done + * updating the new sw to hw queue mappings. + */ + list_for_each_entry(q, &set->tag_list, tag_set_list) + if (!blk_mq_elv_switch_none(&head, q)) + goto switch_back; + + set->nr_hw_queues = nr_hw_queues; + 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_queue_reinit(q); + } + +switch_back: + list_for_each_entry(q, &set->tag_list, tag_set_list) + blk_mq_elv_switch_back(&head, q); + + list_for_each_entry(q, &set->tag_list, tag_set_list) + blk_mq_unfreeze_queue(q); +} + +void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues) +{ + mutex_lock(&set->tag_list_lock); + __blk_mq_update_nr_hw_queues(set, nr_hw_queues); + mutex_unlock(&set->tag_list_lock); +} +EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues); + +/* Enable polling stats and return whether they were already enabled. */ +static bool blk_poll_stats_enable(struct request_queue *q) +{ + if (test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) || + blk_queue_flag_test_and_set(QUEUE_FLAG_POLL_STATS, q)) + return true; + blk_stat_add_callback(q, q->poll_cb); + return false; +} + +static void blk_mq_poll_stats_start(struct request_queue *q) +{ + /* + * We don't arm the callback if polling stats are not enabled or the + * callback is already active. + */ + if (!test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags) || + blk_stat_is_active(q->poll_cb)) + return; + + blk_stat_activate_msecs(q->poll_cb, 100); +} + +static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb) +{ + struct request_queue *q = cb->data; + int bucket; + + for (bucket = 0; bucket < BLK_MQ_POLL_STATS_BKTS; bucket++) { + if (cb->stat[bucket].nr_samples) + q->poll_stat[bucket] = cb->stat[bucket]; + } +} + +static unsigned long blk_mq_poll_nsecs(struct request_queue *q, + struct blk_mq_hw_ctx *hctx, + struct request *rq) +{ + unsigned long ret = 0; + int bucket; + + /* + * If stats collection isn't on, don't sleep but turn it on for + * future users + */ + if (!blk_poll_stats_enable(q)) + return 0; + + /* + * As an optimistic guess, use half of the mean service time + * for this type of request. We can (and should) make this smarter. + * For instance, if the completion latencies are tight, we can + * get closer than just half the mean. This is especially + * important on devices where the completion latencies are longer + * than ~10 usec. We do use the stats for the relevant IO size + * if available which does lead to better estimates. + */ + bucket = blk_mq_poll_stats_bkt(rq); + if (bucket < 0) + return ret; + + if (q->poll_stat[bucket].nr_samples) + ret = (q->poll_stat[bucket].mean + 1) / 2; + + return ret; +} + +static bool blk_mq_poll_hybrid_sleep(struct request_queue *q, + struct blk_mq_hw_ctx *hctx, + struct request *rq) +{ + struct hrtimer_sleeper hs; + enum hrtimer_mode mode; + unsigned int nsecs; + ktime_t kt; + + if (rq->rq_flags & RQF_MQ_POLL_SLEPT) + return false; + + /* + * poll_nsec can be: + * + * -1: don't ever hybrid sleep + * 0: use half of prev avg + * >0: use this specific value + */ + if (q->poll_nsec == -1) + return false; + else if (q->poll_nsec > 0) + nsecs = q->poll_nsec; + else + nsecs = blk_mq_poll_nsecs(q, hctx, rq); + + if (!nsecs) + return false; + + rq->rq_flags |= RQF_MQ_POLL_SLEPT; + + /* + * This will be replaced with the stats tracking code, using + * 'avg_completion_time / 2' as the pre-sleep target. + */ + kt = nsecs; + + mode = HRTIMER_MODE_REL; + hrtimer_init_on_stack(&hs.timer, CLOCK_MONOTONIC, mode); + hrtimer_set_expires(&hs.timer, kt); + + hrtimer_init_sleeper(&hs, current); + do { + if (blk_mq_rq_state(rq) == MQ_RQ_COMPLETE) + break; + set_current_state(TASK_UNINTERRUPTIBLE); + hrtimer_start_expires(&hs.timer, mode); + if (hs.task) + io_schedule(); + hrtimer_cancel(&hs.timer); + mode = HRTIMER_MODE_ABS; + } while (hs.task && !signal_pending(current)); + + __set_current_state(TASK_RUNNING); + destroy_hrtimer_on_stack(&hs.timer); + return true; +} + +static bool __blk_mq_poll(struct blk_mq_hw_ctx *hctx, struct request *rq) +{ + struct request_queue *q = hctx->queue; + long state; + + /* + * If we sleep, have the caller restart the poll loop to reset + * the state. Like for the other success return cases, the + * caller is responsible for checking if the IO completed. If + * the IO isn't complete, we'll get called again and will go + * straight to the busy poll loop. + */ + if (blk_mq_poll_hybrid_sleep(q, hctx, rq)) + return true; + + hctx->poll_considered++; + + state = current->state; + while (!need_resched()) { + int ret; + + hctx->poll_invoked++; + + ret = q->mq_ops->poll(hctx, rq->tag); + if (ret > 0) { + hctx->poll_success++; + set_current_state(TASK_RUNNING); + return true; + } + + if (signal_pending_state(state, current)) + set_current_state(TASK_RUNNING); + + if (current->state == TASK_RUNNING) + return true; + if (ret < 0) + break; + cpu_relax(); + } + + __set_current_state(TASK_RUNNING); + return false; +} + +static bool blk_mq_poll(struct request_queue *q, blk_qc_t cookie) +{ + struct blk_mq_hw_ctx *hctx; + struct request *rq; + + if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags)) + return false; + + hctx = q->queue_hw_ctx[blk_qc_t_to_queue_num(cookie)]; + if (!blk_qc_t_is_internal(cookie)) + rq = blk_mq_tag_to_rq(hctx->tags, blk_qc_t_to_tag(cookie)); + else { + rq = blk_mq_tag_to_rq(hctx->sched_tags, blk_qc_t_to_tag(cookie)); + /* + * With scheduling, if the request has completed, we'll + * get a NULL return here, as we clear the sched tag when + * that happens. The request still remains valid, like always, + * so we should be safe with just the NULL check. + */ + if (!rq) + return false; + } + + return __blk_mq_poll(hctx, rq); +} + +static int __init blk_mq_init(void) +{ + cpuhp_setup_state_multi(CPUHP_BLK_MQ_DEAD, "block/mq:dead", NULL, + blk_mq_hctx_notify_dead); + return 0; +} +subsys_initcall(blk_mq_init); |