1 files changed, 167 insertions, 79 deletions

diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index 109611445d40..e2ce4a28e6c9 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -59,19 +59,17 @@ static bool blk_mq_dispatch_hctx_list(struct list_head *rq_list)
 		list_first_entry(rq_list, struct request, queuelist)->mq_hctx;
 	struct request *rq;
 	LIST_HEAD(hctx_list);
-	unsigned int count = 0;
 
 	list_for_each_entry(rq, rq_list, queuelist) {
 		if (rq->mq_hctx != hctx) {
 			list_cut_before(&hctx_list, rq_list, &rq->queuelist);
 			goto dispatch;
 		}
-		count++;
 	}
 	list_splice_tail_init(rq_list, &hctx_list);
 
 dispatch:
-	return blk_mq_dispatch_rq_list(hctx, &hctx_list, count);
+	return blk_mq_dispatch_rq_list(hctx, &hctx_list, false);
 }
 
 #define BLK_MQ_BUDGET_DELAY	3		/* ms units */
@@ -167,7 +165,7 @@ static int __blk_mq_do_dispatch_sched(struct blk_mq_hw_ctx *hctx)
 			dispatched |= blk_mq_dispatch_hctx_list(&rq_list);
 		} while (!list_empty(&rq_list));
 	} else {
-		dispatched = blk_mq_dispatch_rq_list(hctx, &rq_list, count);
+		dispatched = blk_mq_dispatch_rq_list(hctx, &rq_list, false);
 	}
 
 	if (busy)
@@ -261,7 +259,7 @@ static int blk_mq_do_dispatch_ctx(struct blk_mq_hw_ctx *hctx)
 		/* round robin for fair dispatch */
 		ctx = blk_mq_next_ctx(hctx, rq->mq_ctx);
 
-	} while (blk_mq_dispatch_rq_list(rq->mq_hctx, &rq_list, 1));
+	} while (blk_mq_dispatch_rq_list(rq->mq_hctx, &rq_list, false));
 
 	WRITE_ONCE(hctx->dispatch_from, ctx);
 	return ret;
@@ -298,7 +296,7 @@ static int __blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
 	 */
 	if (!list_empty(&rq_list)) {
 		blk_mq_sched_mark_restart_hctx(hctx);
-		if (!blk_mq_dispatch_rq_list(hctx, &rq_list, 0))
+		if (!blk_mq_dispatch_rq_list(hctx, &rq_list, true))
 			return 0;
 		need_dispatch = true;
 	} else {
@@ -312,7 +310,7 @@ static int __blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
 	if (need_dispatch)
 		return blk_mq_do_dispatch_ctx(hctx);
 	blk_mq_flush_busy_ctxs(hctx, &rq_list);
-	blk_mq_dispatch_rq_list(hctx, &rq_list, 0);
+	blk_mq_dispatch_rq_list(hctx, &rq_list, true);
 	return 0;
 }
 
@@ -376,68 +374,177 @@ bool blk_mq_sched_try_insert_merge(struct request_queue *q, struct request *rq,
 }
 EXPORT_SYMBOL_GPL(blk_mq_sched_try_insert_merge);
 
-static int blk_mq_sched_alloc_map_and_rqs(struct request_queue *q,
-					  struct blk_mq_hw_ctx *hctx,
-					  unsigned int hctx_idx)
+/* called in queue's release handler, tagset has gone away */
+static void blk_mq_sched_tags_teardown(struct request_queue *q, unsigned int flags)
 {
-	if (blk_mq_is_shared_tags(q->tag_set->flags)) {
-		hctx->sched_tags = q->sched_shared_tags;
-		return 0;
-	}
+	struct blk_mq_hw_ctx *hctx;
+	unsigned long i;
 
-	hctx->sched_tags = blk_mq_alloc_map_and_rqs(q->tag_set, hctx_idx,
-						    q->nr_requests);
+	queue_for_each_hw_ctx(q, hctx, i)
+		hctx->sched_tags = NULL;
 
-	if (!hctx->sched_tags)
-		return -ENOMEM;
-	return 0;
+	if (blk_mq_is_shared_tags(flags))
+		q->sched_shared_tags = NULL;
 }
 
-static void blk_mq_exit_sched_shared_tags(struct request_queue *queue)
+void blk_mq_sched_reg_debugfs(struct request_queue *q)
 {
-	blk_mq_free_rq_map(queue->sched_shared_tags);
-	queue->sched_shared_tags = NULL;
+	struct blk_mq_hw_ctx *hctx;
+	unsigned long i;
+
+	mutex_lock(&q->debugfs_mutex);
+	blk_mq_debugfs_register_sched(q);
+	queue_for_each_hw_ctx(q, hctx, i)
+		blk_mq_debugfs_register_sched_hctx(q, hctx);
+	mutex_unlock(&q->debugfs_mutex);
 }
 
-/* called in queue's release handler, tagset has gone away */
-static void blk_mq_sched_tags_teardown(struct request_queue *q, unsigned int flags)
+void blk_mq_sched_unreg_debugfs(struct request_queue *q)
 {
 	struct blk_mq_hw_ctx *hctx;
 	unsigned long i;
 
-	queue_for_each_hw_ctx(q, hctx, i) {
-		if (hctx->sched_tags) {
-			if (!blk_mq_is_shared_tags(flags))
-				blk_mq_free_rq_map(hctx->sched_tags);
-			hctx->sched_tags = NULL;
-		}
+	mutex_lock(&q->debugfs_mutex);
+	queue_for_each_hw_ctx(q, hctx, i)
+		blk_mq_debugfs_unregister_sched_hctx(hctx);
+	blk_mq_debugfs_unregister_sched(q);
+	mutex_unlock(&q->debugfs_mutex);
+}
+
+void blk_mq_free_sched_tags(struct elevator_tags *et,
+		struct blk_mq_tag_set *set)
+{
+	unsigned long i;
+
+	/* Shared tags are stored at index 0 in @tags. */
+	if (blk_mq_is_shared_tags(set->flags))
+		blk_mq_free_map_and_rqs(set, et->tags[0], BLK_MQ_NO_HCTX_IDX);
+	else {
+		for (i = 0; i < et->nr_hw_queues; i++)
+			blk_mq_free_map_and_rqs(set, et->tags[i], i);
 	}
 
-	if (blk_mq_is_shared_tags(flags))
-		blk_mq_exit_sched_shared_tags(q);
+	kfree(et);
 }
 
-static int blk_mq_init_sched_shared_tags(struct request_queue *queue)
+void blk_mq_free_sched_tags_batch(struct xarray *et_table,
+		struct blk_mq_tag_set *set)
 {
-	struct blk_mq_tag_set *set = queue->tag_set;
+	struct request_queue *q;
+	struct elevator_tags *et;
 
+	lockdep_assert_held_write(&set->update_nr_hwq_lock);
+
+	list_for_each_entry(q, &set->tag_list, tag_set_list) {
+		/*
+		 * Accessing q->elevator without holding q->elevator_lock is
+		 * safe because we're holding here set->update_nr_hwq_lock in
+		 * the writer context. So, scheduler update/switch code (which
+		 * acquires the same lock but in the reader context) can't run
+		 * concurrently.
+		 */
+		if (q->elevator) {
+			et = xa_load(et_table, q->id);
+			if (unlikely(!et))
+				WARN_ON_ONCE(1);
+			else
+				blk_mq_free_sched_tags(et, set);
+		}
+	}
+}
+
+struct elevator_tags *blk_mq_alloc_sched_tags(struct blk_mq_tag_set *set,
+		unsigned int nr_hw_queues)
+{
+	unsigned int nr_tags;
+	int i;
+	struct elevator_tags *et;
+	gfp_t gfp = GFP_NOIO | __GFP_ZERO | __GFP_NOWARN | __GFP_NORETRY;
+
+	if (blk_mq_is_shared_tags(set->flags))
+		nr_tags = 1;
+	else
+		nr_tags = nr_hw_queues;
+
+	et = kmalloc(sizeof(struct elevator_tags) +
+			nr_tags * sizeof(struct blk_mq_tags *), gfp);
+	if (!et)
+		return NULL;
 	/*
-	 * Set initial depth at max so that we don't need to reallocate for
-	 * updating nr_requests.
+	 * Default to double of smaller one between hw queue_depth and
+	 * 128, since we don't split into sync/async like the old code
+	 * did. Additionally, this is a per-hw queue depth.
 	 */
-	queue->sched_shared_tags = blk_mq_alloc_map_and_rqs(set,
-						BLK_MQ_NO_HCTX_IDX,
-						MAX_SCHED_RQ);
-	if (!queue->sched_shared_tags)
-		return -ENOMEM;
+	et->nr_requests = 2 * min_t(unsigned int, set->queue_depth,
+			BLKDEV_DEFAULT_RQ);
+	et->nr_hw_queues = nr_hw_queues;
+
+	if (blk_mq_is_shared_tags(set->flags)) {
+		/* Shared tags are stored at index 0 in @tags. */
+		et->tags[0] = blk_mq_alloc_map_and_rqs(set, BLK_MQ_NO_HCTX_IDX,
+					MAX_SCHED_RQ);
+		if (!et->tags[0])
+			goto out;
+	} else {
+		for (i = 0; i < et->nr_hw_queues; i++) {
+			et->tags[i] = blk_mq_alloc_map_and_rqs(set, i,
+					et->nr_requests);
+			if (!et->tags[i])
+				goto out_unwind;
+		}
+	}
 
-	blk_mq_tag_update_sched_shared_tags(queue);
+	return et;
+out_unwind:
+	while (--i >= 0)
+		blk_mq_free_map_and_rqs(set, et->tags[i], i);
+out:
+	kfree(et);
+	return NULL;
+}
+
+int blk_mq_alloc_sched_tags_batch(struct xarray *et_table,
+		struct blk_mq_tag_set *set, unsigned int nr_hw_queues)
+{
+	struct request_queue *q;
+	struct elevator_tags *et;
+	gfp_t gfp = GFP_NOIO | __GFP_ZERO | __GFP_NOWARN | __GFP_NORETRY;
 
+	lockdep_assert_held_write(&set->update_nr_hwq_lock);
+
+	list_for_each_entry(q, &set->tag_list, tag_set_list) {
+		/*
+		 * Accessing q->elevator without holding q->elevator_lock is
+		 * safe because we're holding here set->update_nr_hwq_lock in
+		 * the writer context. So, scheduler update/switch code (which
+		 * acquires the same lock but in the reader context) can't run
+		 * concurrently.
+		 */
+		if (q->elevator) {
+			et = blk_mq_alloc_sched_tags(set, nr_hw_queues);
+			if (!et)
+				goto out_unwind;
+			if (xa_insert(et_table, q->id, et, gfp))
+				goto out_free_tags;
+		}
+	}
 	return 0;
+out_free_tags:
+	blk_mq_free_sched_tags(et, set);
+out_unwind:
+	list_for_each_entry_continue_reverse(q, &set->tag_list, tag_set_list) {
+		if (q->elevator) {
+			et = xa_load(et_table, q->id);
+			if (et)
+				blk_mq_free_sched_tags(et, set);
+		}
+	}
+	return -ENOMEM;
 }
 
 /* caller must have a reference to @e, will grab another one if successful */
-int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e)
+int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e,
+		struct elevator_tags *et)
 {
 	unsigned int flags = q->tag_set->flags;
 	struct blk_mq_hw_ctx *hctx;
@@ -445,56 +552,44 @@ int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e)
 	unsigned long i;
 	int ret;
 
-	/*
-	 * Default to double of smaller one between hw queue_depth and 128,
-	 * since we don't split into sync/async like the old code did.
-	 * Additionally, this is a per-hw queue depth.
-	 */
-	q->nr_requests = 2 * min_t(unsigned int, q->tag_set->queue_depth,
-				   BLKDEV_DEFAULT_RQ);
+	eq = elevator_alloc(q, e, et);
+	if (!eq)
+		return -ENOMEM;
+
+	q->nr_requests = et->nr_requests;
 
 	if (blk_mq_is_shared_tags(flags)) {
-		ret = blk_mq_init_sched_shared_tags(q);
-		if (ret)
-			return ret;
+		/* Shared tags are stored at index 0 in @et->tags. */
+		q->sched_shared_tags = et->tags[0];
+		blk_mq_tag_update_sched_shared_tags(q);
 	}
 
 	queue_for_each_hw_ctx(q, hctx, i) {
-		ret = blk_mq_sched_alloc_map_and_rqs(q, hctx, i);
-		if (ret)
-			goto err_free_map_and_rqs;
+		if (blk_mq_is_shared_tags(flags))
+			hctx->sched_tags = q->sched_shared_tags;
+		else
+			hctx->sched_tags = et->tags[i];
 	}
 
-	ret = e->ops.init_sched(q, e);
+	ret = e->ops.init_sched(q, eq);
 	if (ret)
-		goto err_free_map_and_rqs;
-
-	mutex_lock(&q->debugfs_mutex);
-	blk_mq_debugfs_register_sched(q);
-	mutex_unlock(&q->debugfs_mutex);
+		goto out;
 
 	queue_for_each_hw_ctx(q, hctx, i) {
 		if (e->ops.init_hctx) {
 			ret = e->ops.init_hctx(hctx, i);
 			if (ret) {
-				eq = q->elevator;
-				blk_mq_sched_free_rqs(q);
 				blk_mq_exit_sched(q, eq);
 				kobject_put(&eq->kobj);
 				return ret;
 			}
 		}
-		mutex_lock(&q->debugfs_mutex);
-		blk_mq_debugfs_register_sched_hctx(q, hctx);
-		mutex_unlock(&q->debugfs_mutex);
 	}
-
 	return 0;
 
-err_free_map_and_rqs:
-	blk_mq_sched_free_rqs(q);
+out:
 	blk_mq_sched_tags_teardown(q, flags);
-
+	kobject_put(&eq->kobj);
 	q->elevator = NULL;
 	return ret;
 }
@@ -527,10 +622,6 @@ void blk_mq_exit_sched(struct request_queue *q, struct elevator_queue *e)
 	unsigned int flags = 0;
 
 	queue_for_each_hw_ctx(q, hctx, i) {
-		mutex_lock(&q->debugfs_mutex);
-		blk_mq_debugfs_unregister_sched_hctx(hctx);
-		mutex_unlock(&q->debugfs_mutex);
-
 		if (e->type->ops.exit_hctx && hctx->sched_data) {
 			e->type->ops.exit_hctx(hctx, i);
 			hctx->sched_data = NULL;
@@ -538,12 +629,9 @@ void blk_mq_exit_sched(struct request_queue *q, struct elevator_queue *e)
 		flags = hctx->flags;
 	}
 
-	mutex_lock(&q->debugfs_mutex);
-	blk_mq_debugfs_unregister_sched(q);
-	mutex_unlock(&q->debugfs_mutex);
-
 	if (e->type->ops.exit_sched)
 		e->type->ops.exit_sched(e);
 	blk_mq_sched_tags_teardown(q, flags);
+	set_bit(ELEVATOR_FLAG_DYING, &q->elevator->flags);
 	q->elevator = NULL;
 }