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-rw-r--r--block/blk-mq.c2286
1 files changed, 2286 insertions, 0 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c
new file mode 100644
index 000000000..594eea042
--- /dev/null
+++ b/block/blk-mq.c
@@ -0,0 +1,2286 @@
+/*
+ * 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/mm.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/workqueue.h>
+#include <linux/smp.h>
+#include <linux/llist.h>
+#include <linux/list_sort.h>
+#include <linux/cpu.h>
+#include <linux/cache.h>
+#include <linux/sched/sysctl.h>
+#include <linux/delay.h>
+#include <linux/crash_dump.h>
+
+#include <trace/events/block.h>
+
+#include <linux/blk-mq.h>
+#include "blk.h"
+#include "blk-mq.h"
+#include "blk-mq-tag.h"
+
+static DEFINE_MUTEX(all_q_mutex);
+static LIST_HEAD(all_q_list);
+
+static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx);
+
+/*
+ * 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)
+{
+ unsigned int i;
+
+ for (i = 0; i < hctx->ctx_map.size; i++)
+ if (hctx->ctx_map.map[i].word)
+ return true;
+
+ return false;
+}
+
+static inline struct blk_align_bitmap *get_bm(struct blk_mq_hw_ctx *hctx,
+ struct blk_mq_ctx *ctx)
+{
+ return &hctx->ctx_map.map[ctx->index_hw / hctx->ctx_map.bits_per_word];
+}
+
+#define CTX_TO_BIT(hctx, ctx) \
+ ((ctx)->index_hw & ((hctx)->ctx_map.bits_per_word - 1))
+
+/*
+ * 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)
+{
+ struct blk_align_bitmap *bm = get_bm(hctx, ctx);
+
+ if (!test_bit(CTX_TO_BIT(hctx, ctx), &bm->word))
+ set_bit(CTX_TO_BIT(hctx, ctx), &bm->word);
+}
+
+static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx *hctx,
+ struct blk_mq_ctx *ctx)
+{
+ struct blk_align_bitmap *bm = get_bm(hctx, ctx);
+
+ clear_bit(CTX_TO_BIT(hctx, ctx), &bm->word);
+}
+
+static int blk_mq_queue_enter(struct request_queue *q, gfp_t gfp)
+{
+ while (true) {
+ int ret;
+
+ if (percpu_ref_tryget_live(&q->mq_usage_counter))
+ return 0;
+
+ if (!(gfp & __GFP_WAIT))
+ return -EBUSY;
+
+ ret = wait_event_interruptible(q->mq_freeze_wq,
+ !q->mq_freeze_depth || blk_queue_dying(q));
+ if (blk_queue_dying(q))
+ return -ENODEV;
+ if (ret)
+ return ret;
+ }
+}
+
+static void blk_mq_queue_exit(struct request_queue *q)
+{
+ percpu_ref_put(&q->mq_usage_counter);
+}
+
+static void blk_mq_usage_counter_release(struct percpu_ref *ref)
+{
+ struct request_queue *q =
+ container_of(ref, struct request_queue, mq_usage_counter);
+
+ wake_up_all(&q->mq_freeze_wq);
+}
+
+void blk_mq_freeze_queue_start(struct request_queue *q)
+{
+ bool freeze;
+
+ spin_lock_irq(q->queue_lock);
+ freeze = !q->mq_freeze_depth++;
+ spin_unlock_irq(q->queue_lock);
+
+ if (freeze) {
+ percpu_ref_kill(&q->mq_usage_counter);
+ blk_mq_run_hw_queues(q, false);
+ }
+}
+EXPORT_SYMBOL_GPL(blk_mq_freeze_queue_start);
+
+static void blk_mq_freeze_queue_wait(struct request_queue *q)
+{
+ wait_event(q->mq_freeze_wq, percpu_ref_is_zero(&q->mq_usage_counter));
+}
+
+/*
+ * Guarantee no request is in use, so we can change any data structure of
+ * the queue afterward.
+ */
+void blk_mq_freeze_queue(struct request_queue *q)
+{
+ blk_mq_freeze_queue_start(q);
+ blk_mq_freeze_queue_wait(q);
+}
+EXPORT_SYMBOL_GPL(blk_mq_freeze_queue);
+
+void blk_mq_unfreeze_queue(struct request_queue *q)
+{
+ bool wake;
+
+ spin_lock_irq(q->queue_lock);
+ wake = !--q->mq_freeze_depth;
+ WARN_ON_ONCE(q->mq_freeze_depth < 0);
+ spin_unlock_irq(q->queue_lock);
+ if (wake) {
+ percpu_ref_reinit(&q->mq_usage_counter);
+ wake_up_all(&q->mq_freeze_wq);
+ }
+}
+EXPORT_SYMBOL_GPL(blk_mq_unfreeze_queue);
+
+void blk_mq_wake_waiters(struct request_queue *q)
+{
+ struct blk_mq_hw_ctx *hctx;
+ unsigned int i;
+
+ queue_for_each_hw_ctx(q, hctx, i)
+ if (blk_mq_hw_queue_mapped(hctx))
+ blk_mq_tag_wakeup_all(hctx->tags, true);
+
+ /*
+ * If we are called because the queue has now been marked as
+ * dying, we need to ensure that processes currently waiting on
+ * the queue are notified as well.
+ */
+ wake_up_all(&q->mq_freeze_wq);
+}
+
+bool blk_mq_can_queue(struct blk_mq_hw_ctx *hctx)
+{
+ return blk_mq_has_free_tags(hctx->tags);
+}
+EXPORT_SYMBOL(blk_mq_can_queue);
+
+static void blk_mq_rq_ctx_init(struct request_queue *q, struct blk_mq_ctx *ctx,
+ struct request *rq, unsigned int rw_flags)
+{
+ if (blk_queue_io_stat(q))
+ rw_flags |= REQ_IO_STAT;
+
+ INIT_LIST_HEAD(&rq->queuelist);
+ /* csd/requeue_work/fifo_time is initialized before use */
+ rq->q = q;
+ rq->mq_ctx = ctx;
+ rq->cmd_flags |= rw_flags;
+ /* do not touch atomic flags, it needs atomic ops against the timer */
+ rq->cpu = -1;
+ INIT_HLIST_NODE(&rq->hash);
+ RB_CLEAR_NODE(&rq->rb_node);
+ rq->rq_disk = NULL;
+ rq->part = NULL;
+ rq->start_time = jiffies;
+#ifdef CONFIG_BLK_CGROUP
+ rq->rl = NULL;
+ set_start_time_ns(rq);
+ rq->io_start_time_ns = 0;
+#endif
+ rq->nr_phys_segments = 0;
+#if defined(CONFIG_BLK_DEV_INTEGRITY)
+ rq->nr_integrity_segments = 0;
+#endif
+ rq->special = NULL;
+ /* tag was already set */
+ rq->errors = 0;
+
+ rq->cmd = rq->__cmd;
+
+ rq->extra_len = 0;
+ rq->sense_len = 0;
+ rq->resid_len = 0;
+ rq->sense = NULL;
+
+ INIT_LIST_HEAD(&rq->timeout_list);
+ rq->timeout = 0;
+
+ rq->end_io = NULL;
+ rq->end_io_data = NULL;
+ rq->next_rq = NULL;
+
+ ctx->rq_dispatched[rw_is_sync(rw_flags)]++;
+}
+
+static struct request *
+__blk_mq_alloc_request(struct blk_mq_alloc_data *data, int rw)
+{
+ struct request *rq;
+ unsigned int tag;
+
+ tag = blk_mq_get_tag(data);
+ if (tag != BLK_MQ_TAG_FAIL) {
+ rq = data->hctx->tags->rqs[tag];
+
+ if (blk_mq_tag_busy(data->hctx)) {
+ rq->cmd_flags = REQ_MQ_INFLIGHT;
+ atomic_inc(&data->hctx->nr_active);
+ }
+
+ rq->tag = tag;
+ blk_mq_rq_ctx_init(data->q, data->ctx, rq, rw);
+ return rq;
+ }
+
+ return NULL;
+}
+
+struct request *blk_mq_alloc_request(struct request_queue *q, int rw, gfp_t gfp,
+ bool reserved)
+{
+ struct blk_mq_ctx *ctx;
+ struct blk_mq_hw_ctx *hctx;
+ struct request *rq;
+ struct blk_mq_alloc_data alloc_data;
+ int ret;
+
+ ret = blk_mq_queue_enter(q, gfp);
+ if (ret)
+ return ERR_PTR(ret);
+
+ ctx = blk_mq_get_ctx(q);
+ hctx = q->mq_ops->map_queue(q, ctx->cpu);
+ blk_mq_set_alloc_data(&alloc_data, q, gfp & ~__GFP_WAIT,
+ reserved, ctx, hctx);
+
+ rq = __blk_mq_alloc_request(&alloc_data, rw);
+ if (!rq && (gfp & __GFP_WAIT)) {
+ __blk_mq_run_hw_queue(hctx);
+ blk_mq_put_ctx(ctx);
+
+ ctx = blk_mq_get_ctx(q);
+ hctx = q->mq_ops->map_queue(q, ctx->cpu);
+ blk_mq_set_alloc_data(&alloc_data, q, gfp, reserved, ctx,
+ hctx);
+ rq = __blk_mq_alloc_request(&alloc_data, rw);
+ ctx = alloc_data.ctx;
+ }
+ blk_mq_put_ctx(ctx);
+ if (!rq) {
+ blk_mq_queue_exit(q);
+ return ERR_PTR(-EWOULDBLOCK);
+ }
+ return rq;
+}
+EXPORT_SYMBOL(blk_mq_alloc_request);
+
+static void __blk_mq_free_request(struct blk_mq_hw_ctx *hctx,
+ struct blk_mq_ctx *ctx, struct request *rq)
+{
+ const int tag = rq->tag;
+ struct request_queue *q = rq->q;
+
+ if (rq->cmd_flags & REQ_MQ_INFLIGHT)
+ atomic_dec(&hctx->nr_active);
+ rq->cmd_flags = 0;
+
+ clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
+ blk_mq_put_tag(hctx, tag, &ctx->last_tag);
+ blk_mq_queue_exit(q);
+}
+
+void blk_mq_free_hctx_request(struct blk_mq_hw_ctx *hctx, struct request *rq)
+{
+ struct blk_mq_ctx *ctx = rq->mq_ctx;
+
+ ctx->rq_completed[rq_is_sync(rq)]++;
+ __blk_mq_free_request(hctx, ctx, rq);
+
+}
+EXPORT_SYMBOL_GPL(blk_mq_free_hctx_request);
+
+void blk_mq_free_request(struct request *rq)
+{
+ struct blk_mq_hw_ctx *hctx;
+ struct request_queue *q = rq->q;
+
+ hctx = q->mq_ops->map_queue(q, rq->mq_ctx->cpu);
+ blk_mq_free_hctx_request(hctx, rq);
+}
+EXPORT_SYMBOL_GPL(blk_mq_free_request);
+
+inline void __blk_mq_end_request(struct request *rq, int error)
+{
+ blk_account_io_done(rq);
+
+ if (rq->end_io) {
+ rq->end_io(rq, error);
+ } else {
+ if (unlikely(blk_bidi_rq(rq)))
+ blk_mq_free_request(rq->next_rq);
+ blk_mq_free_request(rq);
+ }
+}
+EXPORT_SYMBOL(__blk_mq_end_request);
+
+void blk_mq_end_request(struct request *rq, int error)
+{
+ if (blk_update_request(rq, error, blk_rq_bytes(rq)))
+ BUG();
+ __blk_mq_end_request(rq, error);
+}
+EXPORT_SYMBOL(blk_mq_end_request);
+
+static void __blk_mq_complete_request_remote(void *data)
+{
+ struct request *rq = data;
+
+ rq->q->softirq_done_fn(rq);
+}
+
+static void blk_mq_ipi_complete_request(struct request *rq)
+{
+ struct blk_mq_ctx *ctx = rq->mq_ctx;
+ bool shared = false;
+ int cpu;
+
+ if (!test_bit(QUEUE_FLAG_SAME_COMP, &rq->q->queue_flags)) {
+ rq->q->softirq_done_fn(rq);
+ return;
+ }
+
+ cpu = get_cpu();
+ if (!test_bit(QUEUE_FLAG_SAME_FORCE, &rq->q->queue_flags))
+ shared = cpus_share_cache(cpu, ctx->cpu);
+
+ if (cpu != ctx->cpu && !shared && cpu_online(ctx->cpu)) {
+ rq->csd.func = __blk_mq_complete_request_remote;
+ rq->csd.info = rq;
+ rq->csd.flags = 0;
+ smp_call_function_single_async(ctx->cpu, &rq->csd);
+ } else {
+ rq->q->softirq_done_fn(rq);
+ }
+ put_cpu();
+}
+
+void __blk_mq_complete_request(struct request *rq)
+{
+ struct request_queue *q = rq->q;
+
+ if (!q->softirq_done_fn)
+ blk_mq_end_request(rq, rq->errors);
+ else
+ blk_mq_ipi_complete_request(rq);
+}
+
+/**
+ * blk_mq_complete_request - end I/O on a request
+ * @rq: the request being processed
+ *
+ * Description:
+ * Ends all I/O on a request. It does not handle partial completions.
+ * The actual completion happens out-of-order, through a IPI handler.
+ **/
+void blk_mq_complete_request(struct request *rq)
+{
+ struct request_queue *q = rq->q;
+
+ if (unlikely(blk_should_fake_timeout(q)))
+ return;
+ if (!blk_mark_rq_complete(rq))
+ __blk_mq_complete_request(rq);
+}
+EXPORT_SYMBOL(blk_mq_complete_request);
+
+int blk_mq_request_started(struct request *rq)
+{
+ return test_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
+}
+EXPORT_SYMBOL_GPL(blk_mq_request_started);
+
+void blk_mq_start_request(struct request *rq)
+{
+ struct request_queue *q = rq->q;
+
+ trace_block_rq_issue(q, rq);
+
+ rq->resid_len = blk_rq_bytes(rq);
+ if (unlikely(blk_bidi_rq(rq)))
+ rq->next_rq->resid_len = blk_rq_bytes(rq->next_rq);
+
+ blk_add_timer(rq);
+
+ /*
+ * Ensure that ->deadline is visible before set the started
+ * flag and clear the completed flag.
+ */
+ smp_mb__before_atomic();
+
+ /*
+ * Mark us as started and clear complete. Complete might have been
+ * set if requeue raced with timeout, which then marked it as
+ * complete. So be sure to clear complete again when we start
+ * the request, otherwise we'll ignore the completion event.
+ */
+ if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
+ set_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
+ if (test_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags))
+ clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
+
+ if (q->dma_drain_size && blk_rq_bytes(rq)) {
+ /*
+ * Make sure space for the drain appears. We know we can do
+ * this because max_hw_segments has been adjusted to be one
+ * fewer than the device can handle.
+ */
+ rq->nr_phys_segments++;
+ }
+}
+EXPORT_SYMBOL(blk_mq_start_request);
+
+static void __blk_mq_requeue_request(struct request *rq)
+{
+ struct request_queue *q = rq->q;
+
+ trace_block_rq_requeue(q, rq);
+
+ if (test_and_clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags)) {
+ if (q->dma_drain_size && blk_rq_bytes(rq))
+ rq->nr_phys_segments--;
+ }
+}
+
+void blk_mq_requeue_request(struct request *rq)
+{
+ __blk_mq_requeue_request(rq);
+
+ BUG_ON(blk_queued_rq(rq));
+ blk_mq_add_to_requeue_list(rq, true);
+}
+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);
+ LIST_HEAD(rq_list);
+ struct request *rq, *next;
+ unsigned long flags;
+
+ spin_lock_irqsave(&q->requeue_lock, flags);
+ list_splice_init(&q->requeue_list, &rq_list);
+ spin_unlock_irqrestore(&q->requeue_lock, flags);
+
+ list_for_each_entry_safe(rq, next, &rq_list, queuelist) {
+ if (!(rq->cmd_flags & REQ_SOFTBARRIER))
+ continue;
+
+ rq->cmd_flags &= ~REQ_SOFTBARRIER;
+ list_del_init(&rq->queuelist);
+ blk_mq_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_insert_request(rq, false, false, false);
+ }
+
+ /*
+ * Use the start variant of queue running here, so that running
+ * the requeue work will kick stopped queues.
+ */
+ blk_mq_start_hw_queues(q);
+}
+
+void blk_mq_add_to_requeue_list(struct request *rq, bool at_head)
+{
+ struct request_queue *q = rq->q;
+ unsigned long flags;
+
+ /*
+ * We abuse this flag that is otherwise used by the I/O scheduler to
+ * request head insertation from the workqueue.
+ */
+ BUG_ON(rq->cmd_flags & REQ_SOFTBARRIER);
+
+ spin_lock_irqsave(&q->requeue_lock, flags);
+ if (at_head) {
+ rq->cmd_flags |= REQ_SOFTBARRIER;
+ list_add(&rq->queuelist, &q->requeue_list);
+ } else {
+ list_add_tail(&rq->queuelist, &q->requeue_list);
+ }
+ spin_unlock_irqrestore(&q->requeue_lock, flags);
+}
+EXPORT_SYMBOL(blk_mq_add_to_requeue_list);
+
+void blk_mq_cancel_requeue_work(struct request_queue *q)
+{
+ cancel_work_sync(&q->requeue_work);
+}
+EXPORT_SYMBOL_GPL(blk_mq_cancel_requeue_work);
+
+void blk_mq_kick_requeue_list(struct request_queue *q)
+{
+ kblockd_schedule_work(&q->requeue_work);
+}
+EXPORT_SYMBOL(blk_mq_kick_requeue_list);
+
+void blk_mq_abort_requeue_list(struct request_queue *q)
+{
+ unsigned long flags;
+ LIST_HEAD(rq_list);
+
+ spin_lock_irqsave(&q->requeue_lock, flags);
+ list_splice_init(&q->requeue_list, &rq_list);
+ spin_unlock_irqrestore(&q->requeue_lock, flags);
+
+ while (!list_empty(&rq_list)) {
+ struct request *rq;
+
+ rq = list_first_entry(&rq_list, struct request, queuelist);
+ list_del_init(&rq->queuelist);
+ rq->errors = -EIO;
+ blk_mq_end_request(rq, rq->errors);
+ }
+}
+EXPORT_SYMBOL(blk_mq_abort_requeue_list);
+
+static inline bool is_flush_request(struct request *rq,
+ struct blk_flush_queue *fq, unsigned int tag)
+{
+ return ((rq->cmd_flags & REQ_FLUSH_SEQ) &&
+ fq->flush_rq->tag == tag);
+}
+
+struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag)
+{
+ struct request *rq = tags->rqs[tag];
+ /* mq_ctx of flush rq is always cloned from the corresponding req */
+ struct blk_flush_queue *fq = blk_get_flush_queue(rq->q, rq->mq_ctx);
+
+ if (!is_flush_request(rq, fq, tag))
+ return rq;
+
+ return fq->flush_rq;
+}
+EXPORT_SYMBOL(blk_mq_tag_to_rq);
+
+struct blk_mq_timeout_data {
+ unsigned long next;
+ unsigned int next_set;
+};
+
+void blk_mq_rq_timed_out(struct request *req, bool reserved)
+{
+ struct blk_mq_ops *ops = req->q->mq_ops;
+ enum blk_eh_timer_return ret = BLK_EH_RESET_TIMER;
+
+ /*
+ * We know that complete is set at this point. If STARTED isn't set
+ * anymore, then the request isn't active and the "timeout" should
+ * just be ignored. This can happen due to the bitflag ordering.
+ * Timeout first checks if STARTED is set, and if it is, assumes
+ * the request is active. But if we race with completion, then
+ * we both flags will get cleared. So check here again, and ignore
+ * a timeout event with a request that isn't active.
+ */
+ if (!test_bit(REQ_ATOM_STARTED, &req->atomic_flags))
+ return;
+
+ if (ops->timeout)
+ ret = ops->timeout(req, reserved);
+
+ switch (ret) {
+ case BLK_EH_HANDLED:
+ __blk_mq_complete_request(req);
+ break;
+ case BLK_EH_RESET_TIMER:
+ blk_add_timer(req);
+ blk_clear_rq_complete(req);
+ break;
+ case BLK_EH_NOT_HANDLED:
+ break;
+ default:
+ printk(KERN_ERR "block: bad eh return: %d\n", ret);
+ break;
+ }
+}
+
+static void blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
+ struct request *rq, void *priv, bool reserved)
+{
+ struct blk_mq_timeout_data *data = priv;
+
+ if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags)) {
+ /*
+ * If a request wasn't started before the queue was
+ * marked dying, kill it here or it'll go unnoticed.
+ */
+ if (unlikely(blk_queue_dying(rq->q))) {
+ rq->errors = -EIO;
+ blk_mq_complete_request(rq);
+ }
+ return;
+ }
+ if (rq->cmd_flags & REQ_NO_TIMEOUT)
+ return;
+
+ if (time_after_eq(jiffies, rq->deadline)) {
+ if (!blk_mark_rq_complete(rq))
+ blk_mq_rq_timed_out(rq, reserved);
+ } else if (!data->next_set || time_after(data->next, rq->deadline)) {
+ data->next = rq->deadline;
+ data->next_set = 1;
+ }
+}
+
+static void blk_mq_rq_timer(unsigned long priv)
+{
+ struct request_queue *q = (struct request_queue *)priv;
+ struct blk_mq_timeout_data data = {
+ .next = 0,
+ .next_set = 0,
+ };
+ struct blk_mq_hw_ctx *hctx;
+ int i;
+
+ queue_for_each_hw_ctx(q, hctx, i) {
+ /*
+ * If not software queues are currently mapped to this
+ * hardware queue, there's nothing to check
+ */
+ if (!blk_mq_hw_queue_mapped(hctx))
+ continue;
+
+ blk_mq_tag_busy_iter(hctx, blk_mq_check_expired, &data);
+ }
+
+ if (data.next_set) {
+ data.next = blk_rq_timeout(round_jiffies_up(data.next));
+ mod_timer(&q->timeout, data.next);
+ } else {
+ 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);
+ }
+ }
+}
+
+/*
+ * Reverse check our software queue for entries that we could potentially
+ * merge with. Currently includes a hand-wavy stop count of 8, to not spend
+ * too much time checking for merges.
+ */
+static bool blk_mq_attempt_merge(struct request_queue *q,
+ struct blk_mq_ctx *ctx, struct bio *bio)
+{
+ struct request *rq;
+ int checked = 8;
+
+ list_for_each_entry_reverse(rq, &ctx->rq_list, queuelist) {
+ int el_ret;
+
+ if (!checked--)
+ break;
+
+ if (!blk_rq_merge_ok(rq, bio))
+ continue;
+
+ el_ret = blk_try_merge(rq, bio);
+ if (el_ret == ELEVATOR_BACK_MERGE) {
+ if (bio_attempt_back_merge(q, rq, bio)) {
+ ctx->rq_merged++;
+ return true;
+ }
+ break;
+ } else if (el_ret == ELEVATOR_FRONT_MERGE) {
+ if (bio_attempt_front_merge(q, rq, bio)) {
+ ctx->rq_merged++;
+ return true;
+ }
+ break;
+ }
+ }
+
+ return false;
+}
+
+/*
+ * Process software queues that have been marked busy, splicing them
+ * to the for-dispatch
+ */
+static void flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list)
+{
+ struct blk_mq_ctx *ctx;
+ int i;
+
+ for (i = 0; i < hctx->ctx_map.size; i++) {
+ struct blk_align_bitmap *bm = &hctx->ctx_map.map[i];
+ unsigned int off, bit;
+
+ if (!bm->word)
+ continue;
+
+ bit = 0;
+ off = i * hctx->ctx_map.bits_per_word;
+ do {
+ bit = find_next_bit(&bm->word, bm->depth, bit);
+ if (bit >= bm->depth)
+ break;
+
+ ctx = hctx->ctxs[bit + off];
+ clear_bit(bit, &bm->word);
+ spin_lock(&ctx->lock);
+ list_splice_tail_init(&ctx->rq_list, list);
+ spin_unlock(&ctx->lock);
+
+ bit++;
+ } while (1);
+ }
+}
+
+/*
+ * Run this hardware queue, pulling any software queues mapped to it in.
+ * Note that this function currently has various problems around ordering
+ * of IO. In particular, we'd like FIFO behaviour on handling existing
+ * items on the hctx->dispatch list. Ignore that for now.
+ */
+static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
+{
+ struct request_queue *q = hctx->queue;
+ struct request *rq;
+ LIST_HEAD(rq_list);
+ LIST_HEAD(driver_list);
+ struct list_head *dptr;
+ int queued;
+
+ WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask));
+
+ if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->state)))
+ return;
+
+ hctx->run++;
+
+ /*
+ * Touch any software queue that has pending entries.
+ */
+ flush_busy_ctxs(hctx, &rq_list);
+
+ /*
+ * If we have previous entries on our dispatch list, grab them
+ * and stuff them at the front for more fair dispatch.
+ */
+ if (!list_empty_careful(&hctx->dispatch)) {
+ spin_lock(&hctx->lock);
+ if (!list_empty(&hctx->dispatch))
+ list_splice_init(&hctx->dispatch, &rq_list);
+ spin_unlock(&hctx->lock);
+ }
+
+ /*
+ * Start off with dptr being NULL, so we start the first request
+ * immediately, even if we have more pending.
+ */
+ dptr = NULL;
+
+ /*
+ * Now process all the entries, sending them to the driver.
+ */
+ queued = 0;
+ while (!list_empty(&rq_list)) {
+ struct blk_mq_queue_data bd;
+ int ret;
+
+ rq = list_first_entry(&rq_list, struct request, queuelist);
+ list_del_init(&rq->queuelist);
+
+ bd.rq = rq;
+ bd.list = dptr;
+ bd.last = list_empty(&rq_list);
+
+ ret = q->mq_ops->queue_rq(hctx, &bd);
+ switch (ret) {
+ case BLK_MQ_RQ_QUEUE_OK:
+ queued++;
+ continue;
+ case BLK_MQ_RQ_QUEUE_BUSY:
+ list_add(&rq->queuelist, &rq_list);
+ __blk_mq_requeue_request(rq);
+ break;
+ default:
+ pr_err("blk-mq: bad return on queue: %d\n", ret);
+ case BLK_MQ_RQ_QUEUE_ERROR:
+ rq->errors = -EIO;
+ blk_mq_end_request(rq, rq->errors);
+ break;
+ }
+
+ if (ret == BLK_MQ_RQ_QUEUE_BUSY)
+ break;
+
+ /*
+ * We've done the first request. If we have more than 1
+ * left in the list, set dptr to defer issue.
+ */
+ if (!dptr && rq_list.next != rq_list.prev)
+ dptr = &driver_list;
+ }
+
+ if (!queued)
+ hctx->dispatched[0]++;
+ else if (queued < (1 << (BLK_MQ_MAX_DISPATCH_ORDER - 1)))
+ hctx->dispatched[ilog2(queued) + 1]++;
+
+ /*
+ * Any items that need requeuing? Stuff them into hctx->dispatch,
+ * that is where we will continue on next queue run.
+ */
+ if (!list_empty(&rq_list)) {
+ spin_lock(&hctx->lock);
+ list_splice(&rq_list, &hctx->dispatch);
+ spin_unlock(&hctx->lock);
+ /*
+ * the queue is expected stopped with BLK_MQ_RQ_QUEUE_BUSY, but
+ * it's possible the queue is stopped and restarted again
+ * before this. Queue restart will dispatch requests. And since
+ * requests in rq_list aren't added into hctx->dispatch yet,
+ * the requests in rq_list might get lost.
+ *
+ * blk_mq_run_hw_queue() already checks the STOPPED bit
+ **/
+ blk_mq_run_hw_queue(hctx, true);
+ }
+}
+
+/*
+ * It'd be great if the workqueue API had a way to pass
+ * in a mask and had some smarts for more clever placement.
+ * For now we just round-robin here, switching for every
+ * BLK_MQ_CPU_WORK_BATCH queued items.
+ */
+static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx)
+{
+ if (hctx->queue->nr_hw_queues == 1)
+ return WORK_CPU_UNBOUND;
+
+ if (--hctx->next_cpu_batch <= 0) {
+ int cpu = hctx->next_cpu, next_cpu;
+
+ next_cpu = cpumask_next(hctx->next_cpu, hctx->cpumask);
+ if (next_cpu >= nr_cpu_ids)
+ next_cpu = cpumask_first(hctx->cpumask);
+
+ hctx->next_cpu = next_cpu;
+ hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
+
+ return cpu;
+ }
+
+ return hctx->next_cpu;
+}
+
+void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
+{
+ if (unlikely(test_bit(BLK_MQ_S_STOPPED, &hctx->state) ||
+ !blk_mq_hw_queue_mapped(hctx)))
+ return;
+
+ if (!async) {
+ int cpu = get_cpu();
+ if (cpumask_test_cpu(cpu, hctx->cpumask)) {
+ __blk_mq_run_hw_queue(hctx);
+ put_cpu();
+ return;
+ }
+
+ put_cpu();
+ }
+
+ kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx),
+ &hctx->run_work, 0);
+}
+
+void blk_mq_run_hw_queues(struct request_queue *q, bool async)
+{
+ struct blk_mq_hw_ctx *hctx;
+ int i;
+
+ queue_for_each_hw_ctx(q, hctx, i) {
+ if ((!blk_mq_hctx_has_pending(hctx) &&
+ list_empty_careful(&hctx->dispatch)) ||
+ test_bit(BLK_MQ_S_STOPPED, &hctx->state))
+ continue;
+
+ blk_mq_run_hw_queue(hctx, async);
+ }
+}
+EXPORT_SYMBOL(blk_mq_run_hw_queues);
+
+void blk_mq_stop_hw_queue(struct blk_mq_hw_ctx *hctx)
+{
+ cancel_delayed_work(&hctx->run_work);
+ cancel_delayed_work(&hctx->delay_work);
+ set_bit(BLK_MQ_S_STOPPED, &hctx->state);
+}
+EXPORT_SYMBOL(blk_mq_stop_hw_queue);
+
+void blk_mq_stop_hw_queues(struct request_queue *q)
+{
+ struct blk_mq_hw_ctx *hctx;
+ int i;
+
+ queue_for_each_hw_ctx(q, hctx, i)
+ blk_mq_stop_hw_queue(hctx);
+}
+EXPORT_SYMBOL(blk_mq_stop_hw_queues);
+
+void blk_mq_start_hw_queue(struct blk_mq_hw_ctx *hctx)
+{
+ clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
+
+ blk_mq_run_hw_queue(hctx, false);
+}
+EXPORT_SYMBOL(blk_mq_start_hw_queue);
+
+void blk_mq_start_hw_queues(struct request_queue *q)
+{
+ struct blk_mq_hw_ctx *hctx;
+ int i;
+
+ queue_for_each_hw_ctx(q, hctx, i)
+ blk_mq_start_hw_queue(hctx);
+}
+EXPORT_SYMBOL(blk_mq_start_hw_queues);
+
+void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async)
+{
+ struct blk_mq_hw_ctx *hctx;
+ int i;
+
+ queue_for_each_hw_ctx(q, hctx, i) {
+ if (!test_bit(BLK_MQ_S_STOPPED, &hctx->state))
+ continue;
+
+ clear_bit(BLK_MQ_S_STOPPED, &hctx->state);
+ blk_mq_run_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);
+
+ __blk_mq_run_hw_queue(hctx);
+}
+
+static void blk_mq_delay_work_fn(struct work_struct *work)
+{
+ struct blk_mq_hw_ctx *hctx;
+
+ hctx = container_of(work, struct blk_mq_hw_ctx, delay_work.work);
+
+ if (test_and_clear_bit(BLK_MQ_S_STOPPED, &hctx->state))
+ __blk_mq_run_hw_queue(hctx);
+}
+
+void blk_mq_delay_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
+{
+ if (unlikely(!blk_mq_hw_queue_mapped(hctx)))
+ return;
+
+ kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx),
+ &hctx->delay_work, msecs_to_jiffies(msecs));
+}
+EXPORT_SYMBOL(blk_mq_delay_queue);
+
+static 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;
+
+ 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);
+
+ blk_mq_hctx_mark_pending(hctx, ctx);
+}
+
+void blk_mq_insert_request(struct request *rq, bool at_head, bool run_queue,
+ bool async)
+{
+ struct request_queue *q = rq->q;
+ struct blk_mq_hw_ctx *hctx;
+ struct blk_mq_ctx *ctx = rq->mq_ctx, *current_ctx;
+
+ current_ctx = blk_mq_get_ctx(q);
+ if (!cpu_online(ctx->cpu))
+ rq->mq_ctx = ctx = current_ctx;
+
+ hctx = q->mq_ops->map_queue(q, ctx->cpu);
+
+ spin_lock(&ctx->lock);
+ __blk_mq_insert_request(hctx, rq, at_head);
+ spin_unlock(&ctx->lock);
+
+ if (run_queue)
+ blk_mq_run_hw_queue(hctx, async);
+
+ blk_mq_put_ctx(current_ctx);
+}
+
+static void blk_mq_insert_requests(struct request_queue *q,
+ struct blk_mq_ctx *ctx,
+ struct list_head *list,
+ int depth,
+ bool from_schedule)
+
+{
+ struct blk_mq_hw_ctx *hctx;
+ struct blk_mq_ctx *current_ctx;
+
+ trace_block_unplug(q, depth, !from_schedule);
+
+ current_ctx = blk_mq_get_ctx(q);
+
+ if (!cpu_online(ctx->cpu))
+ ctx = current_ctx;
+ hctx = q->mq_ops->map_queue(q, ctx->cpu);
+
+ /*
+ * preemption doesn't flush plug list, so it's possible ctx->cpu is
+ * offline now
+ */
+ spin_lock(&ctx->lock);
+ while (!list_empty(list)) {
+ struct request *rq;
+
+ rq = list_first_entry(list, struct request, queuelist);
+ list_del_init(&rq->queuelist);
+ rq->mq_ctx = ctx;
+ __blk_mq_insert_request(hctx, rq, false);
+ }
+ spin_unlock(&ctx->lock);
+
+ blk_mq_run_hw_queue(hctx, from_schedule);
+ blk_mq_put_ctx(current_ctx);
+}
+
+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) {
+ blk_mq_insert_requests(this_q, this_ctx,
+ &ctx_list, depth,
+ 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) {
+ blk_mq_insert_requests(this_q, this_ctx, &ctx_list, depth,
+ from_schedule);
+ }
+}
+
+static void blk_mq_bio_to_request(struct request *rq, struct bio *bio)
+{
+ init_request_from_bio(rq, bio);
+
+ if (blk_do_io_stat(rq))
+ blk_account_io_start(rq, 1);
+}
+
+static inline bool hctx_allow_merges(struct blk_mq_hw_ctx *hctx)
+{
+ return (hctx->flags & BLK_MQ_F_SHOULD_MERGE) &&
+ !blk_queue_nomerges(hctx->queue);
+}
+
+static inline bool blk_mq_merge_queue_io(struct blk_mq_hw_ctx *hctx,
+ struct blk_mq_ctx *ctx,
+ struct request *rq, struct bio *bio)
+{
+ if (!hctx_allow_merges(hctx)) {
+ blk_mq_bio_to_request(rq, bio);
+ spin_lock(&ctx->lock);
+insert_rq:
+ __blk_mq_insert_request(hctx, rq, false);
+ spin_unlock(&ctx->lock);
+ return false;
+ } else {
+ struct request_queue *q = hctx->queue;
+
+ spin_lock(&ctx->lock);
+ if (!blk_mq_attempt_merge(q, ctx, bio)) {
+ blk_mq_bio_to_request(rq, bio);
+ goto insert_rq;
+ }
+
+ spin_unlock(&ctx->lock);
+ __blk_mq_free_request(hctx, ctx, rq);
+ return true;
+ }
+}
+
+struct blk_map_ctx {
+ struct blk_mq_hw_ctx *hctx;
+ struct blk_mq_ctx *ctx;
+};
+
+static struct request *blk_mq_map_request(struct request_queue *q,
+ struct bio *bio,
+ struct blk_map_ctx *data)
+{
+ struct blk_mq_hw_ctx *hctx;
+ struct blk_mq_ctx *ctx;
+ struct request *rq;
+ int rw = bio_data_dir(bio);
+ struct blk_mq_alloc_data alloc_data;
+
+ if (unlikely(blk_mq_queue_enter(q, GFP_KERNEL))) {
+ bio_endio(bio, -EIO);
+ return NULL;
+ }
+
+ ctx = blk_mq_get_ctx(q);
+ hctx = q->mq_ops->map_queue(q, ctx->cpu);
+
+ if (rw_is_sync(bio->bi_rw))
+ rw |= REQ_SYNC;
+
+ trace_block_getrq(q, bio, rw);
+ blk_mq_set_alloc_data(&alloc_data, q, GFP_ATOMIC, false, ctx,
+ hctx);
+ rq = __blk_mq_alloc_request(&alloc_data, rw);
+ if (unlikely(!rq)) {
+ __blk_mq_run_hw_queue(hctx);
+ blk_mq_put_ctx(ctx);
+ trace_block_sleeprq(q, bio, rw);
+
+ ctx = blk_mq_get_ctx(q);
+ hctx = q->mq_ops->map_queue(q, ctx->cpu);
+ blk_mq_set_alloc_data(&alloc_data, q,
+ __GFP_WAIT|GFP_ATOMIC, false, ctx, hctx);
+ rq = __blk_mq_alloc_request(&alloc_data, rw);
+ ctx = alloc_data.ctx;
+ hctx = alloc_data.hctx;
+ }
+
+ hctx->queued++;
+ data->hctx = hctx;
+ data->ctx = ctx;
+ return rq;
+}
+
+/*
+ * Multiple hardware queue variant. This will not use per-process plugs,
+ * but will attempt to bypass the hctx queueing if we can go straight to
+ * hardware for SYNC IO.
+ */
+static void blk_mq_make_request(struct request_queue *q, struct bio *bio)
+{
+ const int is_sync = rw_is_sync(bio->bi_rw);
+ const int is_flush_fua = bio->bi_rw & (REQ_FLUSH | REQ_FUA);
+ struct blk_map_ctx data;
+ struct request *rq;
+
+ blk_queue_bounce(q, &bio);
+
+ if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
+ bio_endio(bio, -EIO);
+ return;
+ }
+
+ rq = blk_mq_map_request(q, bio, &data);
+ if (unlikely(!rq))
+ return;
+
+ if (unlikely(is_flush_fua)) {
+ blk_mq_bio_to_request(rq, bio);
+ blk_insert_flush(rq);
+ goto run_queue;
+ }
+
+ /*
+ * If the driver supports defer issued based on 'last', then
+ * queue it up like normal since we can potentially save some
+ * CPU this way.
+ */
+ if (is_sync && !(data.hctx->flags & BLK_MQ_F_DEFER_ISSUE)) {
+ struct blk_mq_queue_data bd = {
+ .rq = rq,
+ .list = NULL,
+ .last = 1
+ };
+ int ret;
+
+ blk_mq_bio_to_request(rq, bio);
+
+ /*
+ * For OK queue, we are done. For error, kill it. Any other
+ * error (busy), just add it to our list as we previously
+ * would have done
+ */
+ ret = q->mq_ops->queue_rq(data.hctx, &bd);
+ if (ret == BLK_MQ_RQ_QUEUE_OK)
+ goto done;
+ else {
+ __blk_mq_requeue_request(rq);
+
+ if (ret == BLK_MQ_RQ_QUEUE_ERROR) {
+ rq->errors = -EIO;
+ blk_mq_end_request(rq, rq->errors);
+ goto done;
+ }
+ }
+ }
+
+ if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
+ /*
+ * For a SYNC request, send it to the hardware immediately. For
+ * an ASYNC request, just ensure that we run it later on. The
+ * latter allows for merging opportunities and more efficient
+ * dispatching.
+ */
+run_queue:
+ blk_mq_run_hw_queue(data.hctx, !is_sync || is_flush_fua);
+ }
+done:
+ blk_mq_put_ctx(data.ctx);
+}
+
+/*
+ * Single hardware queue variant. This will attempt to use any per-process
+ * plug for merging and IO deferral.
+ */
+static void blk_sq_make_request(struct request_queue *q, struct bio *bio)
+{
+ const int is_sync = rw_is_sync(bio->bi_rw);
+ const int is_flush_fua = bio->bi_rw & (REQ_FLUSH | REQ_FUA);
+ unsigned int use_plug, request_count = 0;
+ struct blk_map_ctx data;
+ struct request *rq;
+
+ /*
+ * If we have multiple hardware queues, just go directly to
+ * one of those for sync IO.
+ */
+ use_plug = !is_flush_fua && !is_sync;
+
+ blk_queue_bounce(q, &bio);
+
+ if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
+ bio_endio(bio, -EIO);
+ return;
+ }
+
+ if (use_plug && !blk_queue_nomerges(q) &&
+ blk_attempt_plug_merge(q, bio, &request_count))
+ return;
+
+ rq = blk_mq_map_request(q, bio, &data);
+ if (unlikely(!rq))
+ return;
+
+ if (unlikely(is_flush_fua)) {
+ blk_mq_bio_to_request(rq, bio);
+ blk_insert_flush(rq);
+ goto run_queue;
+ }
+
+ /*
+ * A task plug currently exists. Since this is completely lockless,
+ * utilize that to temporarily store requests until the task is
+ * either done or scheduled away.
+ */
+ if (use_plug) {
+ struct blk_plug *plug = current->plug;
+
+ if (plug) {
+ blk_mq_bio_to_request(rq, bio);
+ if (list_empty(&plug->mq_list))
+ trace_block_plug(q);
+ else if (request_count >= BLK_MAX_REQUEST_COUNT) {
+ blk_flush_plug_list(plug, false);
+ trace_block_plug(q);
+ }
+ list_add_tail(&rq->queuelist, &plug->mq_list);
+ blk_mq_put_ctx(data.ctx);
+ return;
+ }
+ }
+
+ if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) {
+ /*
+ * For a SYNC request, send it to the hardware immediately. For
+ * an ASYNC request, just ensure that we run it later on. The
+ * latter allows for merging opportunities and more efficient
+ * dispatching.
+ */
+run_queue:
+ blk_mq_run_hw_queue(data.hctx, !is_sync || is_flush_fua);
+ }
+
+ blk_mq_put_ctx(data.ctx);
+}
+
+/*
+ * Default mapping to a software queue, since we use one per CPU.
+ */
+struct blk_mq_hw_ctx *blk_mq_map_queue(struct request_queue *q, const int cpu)
+{
+ return q->queue_hw_ctx[q->mq_map[cpu]];
+}
+EXPORT_SYMBOL(blk_mq_map_queue);
+
+static void blk_mq_free_rq_map(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++) {
+ if (!tags->rqs[i])
+ continue;
+ set->ops->exit_request(set->driver_data, tags->rqs[i],
+ hctx_idx, i);
+ tags->rqs[i] = NULL;
+ }
+ }
+
+ while (!list_empty(&tags->page_list)) {
+ page = list_first_entry(&tags->page_list, struct page, lru);
+ list_del_init(&page->lru);
+ __free_pages(page, page->private);
+ }
+
+ kfree(tags->rqs);
+
+ blk_mq_free_tags(tags);
+}
+
+static size_t order_to_size(unsigned int order)
+{
+ return (size_t)PAGE_SIZE << order;
+}
+
+static struct blk_mq_tags *blk_mq_init_rq_map(struct blk_mq_tag_set *set,
+ unsigned int hctx_idx)
+{
+ struct blk_mq_tags *tags;
+ unsigned int i, j, entries_per_page, max_order = 4;
+ size_t rq_size, left;
+
+ tags = blk_mq_init_tags(set->queue_depth, set->reserved_tags,
+ set->numa_node,
+ BLK_MQ_FLAG_TO_ALLOC_POLICY(set->flags));
+ if (!tags)
+ return NULL;
+
+ INIT_LIST_HEAD(&tags->page_list);
+
+ tags->rqs = kzalloc_node(set->queue_depth * sizeof(struct request *),
+ GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY,
+ set->numa_node);
+ if (!tags->rqs) {
+ blk_mq_free_tags(tags);
+ return NULL;
+ }
+
+ /*
+ * 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 * set->queue_depth;
+
+ for (i = 0; i < set->queue_depth; ) {
+ int this_order = max_order;
+ struct page *page;
+ int to_do;
+ void *p;
+
+ while (left < order_to_size(this_order - 1) && this_order)
+ this_order--;
+
+ do {
+ page = alloc_pages_node(set->numa_node,
+ GFP_KERNEL | __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);
+ entries_per_page = order_to_size(this_order) / rq_size;
+ to_do = min(entries_per_page, set->queue_depth - i);
+ left -= to_do * rq_size;
+ for (j = 0; j < to_do; j++) {
+ tags->rqs[i] = p;
+ if (set->ops->init_request) {
+ if (set->ops->init_request(set->driver_data,
+ tags->rqs[i], hctx_idx, i,
+ set->numa_node)) {
+ tags->rqs[i] = NULL;
+ goto fail;
+ }
+ }
+
+ p += rq_size;
+ i++;
+ }
+ }
+
+ return tags;
+
+fail:
+ blk_mq_free_rq_map(set, tags, hctx_idx);
+ return NULL;
+}
+
+static void blk_mq_free_bitmap(struct blk_mq_ctxmap *bitmap)
+{
+ kfree(bitmap->map);
+}
+
+static int blk_mq_alloc_bitmap(struct blk_mq_ctxmap *bitmap, int node)
+{
+ unsigned int bpw = 8, total, num_maps, i;
+
+ bitmap->bits_per_word = bpw;
+
+ num_maps = ALIGN(nr_cpu_ids, bpw) / bpw;
+ bitmap->map = kzalloc_node(num_maps * sizeof(struct blk_align_bitmap),
+ GFP_KERNEL, node);
+ if (!bitmap->map)
+ return -ENOMEM;
+
+ total = nr_cpu_ids;
+ for (i = 0; i < num_maps; i++) {
+ bitmap->map[i].depth = min(total, bitmap->bits_per_word);
+ total -= bitmap->map[i].depth;
+ }
+
+ return 0;
+}
+
+static int blk_mq_hctx_cpu_offline(struct blk_mq_hw_ctx *hctx, int cpu)
+{
+ struct request_queue *q = hctx->queue;
+ struct blk_mq_ctx *ctx;
+ LIST_HEAD(tmp);
+
+ /*
+ * Move ctx entries to new CPU, if this one is going away.
+ */
+ ctx = __blk_mq_get_ctx(q, 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 NOTIFY_OK;
+
+ ctx = blk_mq_get_ctx(q);
+ spin_lock(&ctx->lock);
+
+ while (!list_empty(&tmp)) {
+ struct request *rq;
+
+ rq = list_first_entry(&tmp, struct request, queuelist);
+ rq->mq_ctx = ctx;
+ list_move_tail(&rq->queuelist, &ctx->rq_list);
+ }
+
+ hctx = q->mq_ops->map_queue(q, ctx->cpu);
+ blk_mq_hctx_mark_pending(hctx, ctx);
+
+ spin_unlock(&ctx->lock);
+
+ blk_mq_run_hw_queue(hctx, true);
+ blk_mq_put_ctx(ctx);
+ return NOTIFY_OK;
+}
+
+static int blk_mq_hctx_notify(void *data, unsigned long action,
+ unsigned int cpu)
+{
+ struct blk_mq_hw_ctx *hctx = data;
+
+ if (action == CPU_DEAD || action == CPU_DEAD_FROZEN)
+ return blk_mq_hctx_cpu_offline(hctx, cpu);
+
+ /*
+ * In case of CPU online, tags may be reallocated
+ * in blk_mq_map_swqueue() after mapping is updated.
+ */
+
+ return NOTIFY_OK;
+}
+
+/* hctx->ctxs will be freed in queue's release handler */
+static void blk_mq_exit_hctx(struct request_queue *q,
+ struct blk_mq_tag_set *set,
+ struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
+{
+ unsigned flush_start_tag = set->queue_depth;
+
+ blk_mq_tag_idle(hctx);
+
+ if (set->ops->exit_request)
+ set->ops->exit_request(set->driver_data,
+ hctx->fq->flush_rq, hctx_idx,
+ flush_start_tag + hctx_idx);
+
+ if (set->ops->exit_hctx)
+ set->ops->exit_hctx(hctx, hctx_idx);
+
+ blk_mq_unregister_cpu_notifier(&hctx->cpu_notifier);
+ blk_free_flush_queue(hctx->fq);
+ blk_mq_free_bitmap(&hctx->ctx_map);
+}
+
+static void blk_mq_exit_hw_queues(struct request_queue *q,
+ struct blk_mq_tag_set *set, int nr_queue)
+{
+ struct blk_mq_hw_ctx *hctx;
+ unsigned int i;
+
+ queue_for_each_hw_ctx(q, hctx, i) {
+ if (i == nr_queue)
+ break;
+ blk_mq_exit_hctx(q, set, hctx, i);
+ }
+}
+
+static void blk_mq_free_hw_queues(struct request_queue *q,
+ struct blk_mq_tag_set *set)
+{
+ struct blk_mq_hw_ctx *hctx;
+ unsigned int i;
+
+ queue_for_each_hw_ctx(q, hctx, i)
+ free_cpumask_var(hctx->cpumask);
+}
+
+static int blk_mq_init_hctx(struct request_queue *q,
+ struct blk_mq_tag_set *set,
+ struct blk_mq_hw_ctx *hctx, unsigned hctx_idx)
+{
+ int node;
+ unsigned flush_start_tag = set->queue_depth;
+
+ node = hctx->numa_node;
+ if (node == NUMA_NO_NODE)
+ node = hctx->numa_node = set->numa_node;
+
+ INIT_DELAYED_WORK(&hctx->run_work, blk_mq_run_work_fn);
+ INIT_DELAYED_WORK(&hctx->delay_work, blk_mq_delay_work_fn);
+ spin_lock_init(&hctx->lock);
+ INIT_LIST_HEAD(&hctx->dispatch);
+ hctx->queue = q;
+ hctx->queue_num = hctx_idx;
+ hctx->flags = set->flags;
+
+ blk_mq_init_cpu_notifier(&hctx->cpu_notifier,
+ blk_mq_hctx_notify, hctx);
+ blk_mq_register_cpu_notifier(&hctx->cpu_notifier);
+
+ hctx->tags = set->tags[hctx_idx];
+
+ /*
+ * Allocate space for all possible cpus to avoid allocation at
+ * runtime
+ */
+ hctx->ctxs = kmalloc_node(nr_cpu_ids * sizeof(void *),
+ GFP_KERNEL, node);
+ if (!hctx->ctxs)
+ goto unregister_cpu_notifier;
+
+ if (blk_mq_alloc_bitmap(&hctx->ctx_map, node))
+ goto free_ctxs;
+
+ hctx->nr_ctx = 0;
+
+ if (set->ops->init_hctx &&
+ set->ops->init_hctx(hctx, set->driver_data, hctx_idx))
+ goto free_bitmap;
+
+ hctx->fq = blk_alloc_flush_queue(q, hctx->numa_node, set->cmd_size);
+ if (!hctx->fq)
+ goto exit_hctx;
+
+ if (set->ops->init_request &&
+ set->ops->init_request(set->driver_data,
+ hctx->fq->flush_rq, hctx_idx,
+ flush_start_tag + hctx_idx, node))
+ goto free_fq;
+
+ return 0;
+
+ free_fq:
+ kfree(hctx->fq);
+ exit_hctx:
+ if (set->ops->exit_hctx)
+ set->ops->exit_hctx(hctx, hctx_idx);
+ free_bitmap:
+ blk_mq_free_bitmap(&hctx->ctx_map);
+ free_ctxs:
+ kfree(hctx->ctxs);
+ unregister_cpu_notifier:
+ blk_mq_unregister_cpu_notifier(&hctx->cpu_notifier);
+
+ return -1;
+}
+
+static int blk_mq_init_hw_queues(struct request_queue *q,
+ struct blk_mq_tag_set *set)
+{
+ struct blk_mq_hw_ctx *hctx;
+ unsigned int i;
+
+ /*
+ * Initialize hardware queues
+ */
+ queue_for_each_hw_ctx(q, hctx, i) {
+ if (blk_mq_init_hctx(q, set, hctx, i))
+ break;
+ }
+
+ if (i == q->nr_hw_queues)
+ return 0;
+
+ /*
+ * Init failed
+ */
+ blk_mq_exit_hw_queues(q, set, i);
+
+ return 1;
+}
+
+static void blk_mq_init_cpu_queues(struct request_queue *q,
+ unsigned int nr_hw_queues)
+{
+ unsigned int i;
+
+ for_each_possible_cpu(i) {
+ struct blk_mq_ctx *__ctx = per_cpu_ptr(q->queue_ctx, i);
+ struct blk_mq_hw_ctx *hctx;
+
+ memset(__ctx, 0, sizeof(*__ctx));
+ __ctx->cpu = i;
+ spin_lock_init(&__ctx->lock);
+ INIT_LIST_HEAD(&__ctx->rq_list);
+ __ctx->queue = q;
+
+ /* If the cpu isn't online, the cpu is mapped to first hctx */
+ if (!cpu_online(i))
+ continue;
+
+ hctx = q->mq_ops->map_queue(q, i);
+
+ /*
+ * Set local node, IFF we have more than one hw queue. If
+ * not, we remain on the home node of the device
+ */
+ if (nr_hw_queues > 1 && hctx->numa_node == NUMA_NO_NODE)
+ hctx->numa_node = cpu_to_node(i);
+ }
+}
+
+static void blk_mq_map_swqueue(struct request_queue *q)
+{
+ unsigned int 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;
+ }
+
+ /*
+ * Map software to hardware queues
+ */
+ queue_for_each_ctx(q, ctx, i) {
+ /* If the cpu isn't online, the cpu is mapped to first hctx */
+ if (!cpu_online(i))
+ continue;
+
+ hctx = q->mq_ops->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) {
+ struct blk_mq_ctxmap *map = &hctx->ctx_map;
+
+ /*
+ * If no software queues are mapped to this hardware queue,
+ * disable it and free the request entries.
+ */
+ if (!hctx->nr_ctx) {
+ if (set->tags[i]) {
+ blk_mq_free_rq_map(set, set->tags[i], i);
+ set->tags[i] = NULL;
+ }
+ hctx->tags = NULL;
+ continue;
+ }
+
+ /* unmapped hw queue can be remapped after CPU topo changed */
+ if (!set->tags[i])
+ set->tags[i] = blk_mq_init_rq_map(set, i);
+ 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.
+ */
+ map->size = DIV_ROUND_UP(hctx->nr_ctx, map->bits_per_word);
+
+ /*
+ * Initialize batch roundrobin counts
+ */
+ hctx->next_cpu = cpumask_first(hctx->cpumask);
+ hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;
+ }
+}
+
+static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set *set)
+{
+ struct blk_mq_hw_ctx *hctx;
+ struct request_queue *q;
+ bool shared;
+ int i;
+
+ if (set->tag_list.next == set->tag_list.prev)
+ shared = false;
+ else
+ shared = true;
+
+ list_for_each_entry(q, &set->tag_list, tag_set_list) {
+ blk_mq_freeze_queue(q);
+
+ 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;
+ }
+ blk_mq_unfreeze_queue(q);
+ }
+}
+
+static void blk_mq_del_queue_tag_set(struct request_queue *q)
+{
+ struct blk_mq_tag_set *set = q->tag_set;
+
+ mutex_lock(&set->tag_list_lock);
+ list_del_init(&q->tag_set_list);
+ blk_mq_update_tag_set_depth(set);
+ mutex_unlock(&set->tag_list_lock);
+}
+
+static void blk_mq_add_queue_tag_set(struct blk_mq_tag_set *set,
+ struct request_queue *q)
+{
+ q->tag_set = set;
+
+ mutex_lock(&set->tag_list_lock);
+ list_add_tail(&q->tag_set_list, &set->tag_list);
+ blk_mq_update_tag_set_depth(set);
+ 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;
+ kfree(hctx->ctxs);
+ kfree(hctx);
+ }
+
+ kfree(q->queue_hw_ctx);
+
+ /* ctx kobj stays in queue_ctx */
+ free_percpu(q->queue_ctx);
+}
+
+struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
+{
+ struct request_queue *uninit_q, *q;
+
+ uninit_q = blk_alloc_queue_node(GFP_KERNEL, set->numa_node);
+ if (!uninit_q)
+ return ERR_PTR(-ENOMEM);
+
+ q = blk_mq_init_allocated_queue(set, uninit_q);
+ if (IS_ERR(q))
+ blk_cleanup_queue(uninit_q);
+
+ return q;
+}
+EXPORT_SYMBOL(blk_mq_init_queue);
+
+struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
+ struct request_queue *q)
+{
+ struct blk_mq_hw_ctx **hctxs;
+ struct blk_mq_ctx __percpu *ctx;
+ unsigned int *map;
+ int i;
+
+ ctx = alloc_percpu(struct blk_mq_ctx);
+ if (!ctx)
+ return ERR_PTR(-ENOMEM);
+
+ hctxs = kmalloc_node(set->nr_hw_queues * sizeof(*hctxs), GFP_KERNEL,
+ set->numa_node);
+
+ if (!hctxs)
+ goto err_percpu;
+
+ map = blk_mq_make_queue_map(set);
+ if (!map)
+ goto err_map;
+
+ for (i = 0; i < set->nr_hw_queues; i++) {
+ int node = blk_mq_hw_queue_to_node(map, i);
+
+ hctxs[i] = kzalloc_node(sizeof(struct blk_mq_hw_ctx),
+ GFP_KERNEL, node);
+ if (!hctxs[i])
+ goto err_hctxs;
+
+ if (!zalloc_cpumask_var_node(&hctxs[i]->cpumask, GFP_KERNEL,
+ node))
+ goto err_hctxs;
+
+ atomic_set(&hctxs[i]->nr_active, 0);
+ hctxs[i]->numa_node = node;
+ hctxs[i]->queue_num = i;
+ }
+
+ /*
+ * Init percpu_ref in atomic mode so that it's faster to shutdown.
+ * See blk_register_queue() for details.
+ */
+ if (percpu_ref_init(&q->mq_usage_counter, blk_mq_usage_counter_release,
+ PERCPU_REF_INIT_ATOMIC, GFP_KERNEL))
+ goto err_hctxs;
+
+ setup_timer(&q->timeout, blk_mq_rq_timer, (unsigned long) q);
+ blk_queue_rq_timeout(q, set->timeout ? set->timeout : 30000);
+
+ q->nr_queues = nr_cpu_ids;
+ q->nr_hw_queues = set->nr_hw_queues;
+ q->mq_map = map;
+
+ q->queue_ctx = ctx;
+ q->queue_hw_ctx = hctxs;
+
+ q->mq_ops = set->ops;
+ q->queue_flags |= QUEUE_FLAG_MQ_DEFAULT;
+
+ if (!(set->flags & BLK_MQ_F_SG_MERGE))
+ q->queue_flags |= 1 << QUEUE_FLAG_NO_SG_MERGE;
+
+ q->sg_reserved_size = INT_MAX;
+
+ INIT_WORK(&q->requeue_work, blk_mq_requeue_work);
+ INIT_LIST_HEAD(&q->requeue_list);
+ spin_lock_init(&q->requeue_lock);
+
+ if (q->nr_hw_queues > 1)
+ blk_queue_make_request(q, blk_mq_make_request);
+ else
+ blk_queue_make_request(q, blk_sq_make_request);
+
+ /*
+ * Do this after blk_queue_make_request() overrides it...
+ */
+ q->nr_requests = set->queue_depth;
+
+ if (set->ops->complete)
+ blk_queue_softirq_done(q, set->ops->complete);
+
+ blk_mq_init_cpu_queues(q, set->nr_hw_queues);
+
+ if (blk_mq_init_hw_queues(q, set))
+ goto err_hctxs;
+
+ mutex_lock(&all_q_mutex);
+ list_add_tail(&q->all_q_node, &all_q_list);
+ mutex_unlock(&all_q_mutex);
+
+ blk_mq_add_queue_tag_set(set, q);
+
+ blk_mq_map_swqueue(q);
+
+ return q;
+
+err_hctxs:
+ kfree(map);
+ for (i = 0; i < set->nr_hw_queues; i++) {
+ if (!hctxs[i])
+ break;
+ free_cpumask_var(hctxs[i]->cpumask);
+ kfree(hctxs[i]);
+ }
+err_map:
+ kfree(hctxs);
+err_percpu:
+ free_percpu(ctx);
+ return ERR_PTR(-ENOMEM);
+}
+EXPORT_SYMBOL(blk_mq_init_allocated_queue);
+
+void blk_mq_free_queue(struct request_queue *q)
+{
+ struct blk_mq_tag_set *set = q->tag_set;
+
+ blk_mq_del_queue_tag_set(q);
+
+ blk_mq_exit_hw_queues(q, set, set->nr_hw_queues);
+ blk_mq_free_hw_queues(q, set);
+
+ percpu_ref_exit(&q->mq_usage_counter);
+
+ kfree(q->mq_map);
+
+ q->mq_map = NULL;
+
+ mutex_lock(&all_q_mutex);
+ list_del_init(&q->all_q_node);
+ mutex_unlock(&all_q_mutex);
+}
+
+/* Basically redo blk_mq_init_queue with queue frozen */
+static void blk_mq_queue_reinit(struct request_queue *q)
+{
+ WARN_ON_ONCE(!q->mq_freeze_depth);
+
+ blk_mq_sysfs_unregister(q);
+
+ blk_mq_update_queue_map(q->mq_map, q->nr_hw_queues);
+
+ /*
+ * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe
+ * we should change hctx numa_node according to new topology (this
+ * involves free and re-allocate memory, worthy doing?)
+ */
+
+ blk_mq_map_swqueue(q);
+
+ blk_mq_sysfs_register(q);
+}
+
+static int blk_mq_queue_reinit_notify(struct notifier_block *nb,
+ unsigned long action, void *hcpu)
+{
+ struct request_queue *q;
+
+ /*
+ * Before new mappings are established, hotadded cpu might already
+ * start handling requests. This doesn't break anything as we map
+ * offline CPUs to first hardware queue. We will re-init the queue
+ * below to get optimal settings.
+ */
+ if (action != CPU_DEAD && action != CPU_DEAD_FROZEN &&
+ action != CPU_ONLINE && action != CPU_ONLINE_FROZEN)
+ return NOTIFY_OK;
+
+ mutex_lock(&all_q_mutex);
+
+ /*
+ * We need to freeze and reinit all existing queues. Freezing
+ * involves synchronous wait for an RCU grace period and doing it
+ * one by one may take a long time. Start freezing all queues in
+ * one swoop and then wait for the completions so that freezing can
+ * take place in parallel.
+ */
+ list_for_each_entry(q, &all_q_list, all_q_node)
+ blk_mq_freeze_queue_start(q);
+ list_for_each_entry(q, &all_q_list, all_q_node) {
+ blk_mq_freeze_queue_wait(q);
+
+ /*
+ * timeout handler can't touch hw queue during the
+ * reinitialization
+ */
+ del_timer_sync(&q->timeout);
+ }
+
+ list_for_each_entry(q, &all_q_list, all_q_node)
+ blk_mq_queue_reinit(q);
+
+ list_for_each_entry(q, &all_q_list, all_q_node)
+ blk_mq_unfreeze_queue(q);
+
+ mutex_unlock(&all_q_mutex);
+ return NOTIFY_OK;
+}
+
+static int __blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
+{
+ int i;
+
+ for (i = 0; i < set->nr_hw_queues; i++) {
+ set->tags[i] = blk_mq_init_rq_map(set, i);
+ if (!set->tags[i])
+ goto out_unwind;
+ }
+
+ return 0;
+
+out_unwind:
+ while (--i >= 0)
+ blk_mq_free_rq_map(set, set->tags[i], i);
+
+ return -ENOMEM;
+}
+
+/*
+ * Allocate the request maps associated with this tag_set. Note that this
+ * may reduce the depth asked for, if memory is tight. set->queue_depth
+ * will be updated to reflect the allocated depth.
+ */
+static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
+{
+ unsigned int depth;
+ int err;
+
+ depth = set->queue_depth;
+ do {
+ err = __blk_mq_alloc_rq_maps(set);
+ if (!err)
+ break;
+
+ set->queue_depth >>= 1;
+ if (set->queue_depth < set->reserved_tags + BLK_MQ_TAG_MIN) {
+ err = -ENOMEM;
+ break;
+ }
+ } while (set->queue_depth);
+
+ if (!set->queue_depth || err) {
+ pr_err("blk-mq: failed to allocate request map\n");
+ return -ENOMEM;
+ }
+
+ if (depth != set->queue_depth)
+ pr_info("blk-mq: reduced tag depth (%u -> %u)\n",
+ depth, set->queue_depth);
+
+ return 0;
+}
+
+/*
+ * Alloc a tag set to be associated with one or more request queues.
+ * May fail with EINVAL for various error conditions. May adjust the
+ * requested depth down, if if it too large. In that case, the set
+ * value will be stored in set->queue_depth.
+ */
+int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
+{
+ 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 || !set->ops->map_queue)
+ 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);
+ }
+
+ set->tags = kmalloc_node(set->nr_hw_queues *
+ sizeof(struct blk_mq_tags *),
+ GFP_KERNEL, set->numa_node);
+ if (!set->tags)
+ return -ENOMEM;
+
+ if (blk_mq_alloc_rq_maps(set))
+ goto enomem;
+
+ mutex_init(&set->tag_list_lock);
+ INIT_LIST_HEAD(&set->tag_list);
+
+ return 0;
+enomem:
+ kfree(set->tags);
+ set->tags = NULL;
+ return -ENOMEM;
+}
+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 < set->nr_hw_queues; i++) {
+ if (set->tags[i])
+ blk_mq_free_rq_map(set, set->tags[i], i);
+ }
+
+ 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 || nr > set->queue_depth)
+ return -EINVAL;
+
+ ret = 0;
+ queue_for_each_hw_ctx(q, hctx, i) {
+ ret = blk_mq_tag_update_depth(hctx->tags, nr);
+ if (ret)
+ break;
+ }
+
+ if (!ret)
+ q->nr_requests = nr;
+
+ return ret;
+}
+
+void blk_mq_disable_hotplug(void)
+{
+ mutex_lock(&all_q_mutex);
+}
+
+void blk_mq_enable_hotplug(void)
+{
+ mutex_unlock(&all_q_mutex);
+}
+
+static int __init blk_mq_init(void)
+{
+ blk_mq_cpu_init();
+
+ hotcpu_notifier(blk_mq_queue_reinit_notify, 0);
+
+ return 0;
+}
+subsys_initcall(blk_mq_init);
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2024-11-17 05:54:34 +0000