5 files changed, 178 insertions, 109 deletions

diff --git a/block/bio.c b/block/bio.c
index cf7591551b17..f124a0a624fc 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -296,13 +296,19 @@ void bio_reset(struct bio *bio)
 }
 EXPORT_SYMBOL(bio_reset);
 
-static void bio_chain_endio(struct bio *bio)
+static struct bio *__bio_chain_endio(struct bio *bio)
 {
 	struct bio *parent = bio->bi_private;
 
-	parent->bi_error = bio->bi_error;
-	bio_endio(parent);
+	if (!parent->bi_error)
+		parent->bi_error = bio->bi_error;
 	bio_put(bio);
+	return parent;
+}
+
+static void bio_chain_endio(struct bio *bio)
+{
+	bio_endio(__bio_chain_endio(bio));
 }
 
 /*
@@ -1742,29 +1748,25 @@ static inline bool bio_remaining_done(struct bio *bio)
  **/
 void bio_endio(struct bio *bio)
 {
-	while (bio) {
-		if (unlikely(!bio_remaining_done(bio)))
-			break;
+again:
+	if (!bio_remaining_done(bio))
+		return;
 
-		/*
-		 * Need to have a real endio function for chained bios,
-		 * otherwise various corner cases will break (like stacking
-		 * block devices that save/restore bi_end_io) - however, we want
-		 * to avoid unbounded recursion and blowing the stack. Tail call
-		 * optimization would handle this, but compiling with frame
-		 * pointers also disables gcc's sibling call optimization.
-		 */
-		if (bio->bi_end_io == bio_chain_endio) {
-			struct bio *parent = bio->bi_private;
-			parent->bi_error = bio->bi_error;
-			bio_put(bio);
-			bio = parent;
-		} else {
-			if (bio->bi_end_io)
-				bio->bi_end_io(bio);
-			bio = NULL;
-		}
+	/*
+	 * Need to have a real endio function for chained bios, otherwise
+	 * various corner cases will break (like stacking block devices that
+	 * save/restore bi_end_io) - however, we want to avoid unbounded
+	 * recursion and blowing the stack. Tail call optimization would
+	 * handle this, but compiling with frame pointers also disables
+	 * gcc's sibling call optimization.
+	 */
+	if (bio->bi_end_io == bio_chain_endio) {
+		bio = __bio_chain_endio(bio);
+		goto again;
 	}
+
+	if (bio->bi_end_io)
+		bio->bi_end_io(bio);
 }
 EXPORT_SYMBOL(bio_endio);
 
diff --git a/block/blk-mq-sysfs.c b/block/blk-mq-sysfs.c
index 1cf18784c5cf..431fdda21737 100644
--- a/block/blk-mq-sysfs.c
+++ b/block/blk-mq-sysfs.c
@@ -408,17 +408,18 @@ void blk_mq_unregister_disk(struct gendisk *disk)
 	blk_mq_enable_hotplug();
 }
 
+void blk_mq_hctx_kobj_init(struct blk_mq_hw_ctx *hctx)
+{
+	kobject_init(&hctx->kobj, &blk_mq_hw_ktype);
+}
+
 static void blk_mq_sysfs_init(struct request_queue *q)
 {
-	struct blk_mq_hw_ctx *hctx;
 	struct blk_mq_ctx *ctx;
 	int i;
 
 	kobject_init(&q->mq_kobj, &blk_mq_ktype);
 
-	queue_for_each_hw_ctx(q, hctx, i)
-		kobject_init(&hctx->kobj, &blk_mq_hw_ktype);
-
 	queue_for_each_ctx(q, ctx, i)
 		kobject_init(&ctx->kobj, &blk_mq_ctx_ktype);
 }
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 56c0a726b619..050f7a13021b 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -544,7 +544,10 @@ EXPORT_SYMBOL(blk_mq_abort_requeue_list);
 
 struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag)
 {
-	return tags->rqs[tag];
+	if (tag < tags->nr_tags)
+		return tags->rqs[tag];
+
+	return NULL;
 }
 EXPORT_SYMBOL(blk_mq_tag_to_rq);
 
@@ -1744,31 +1747,6 @@ static int blk_mq_init_hctx(struct request_queue *q,
 	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)
 {
@@ -1826,6 +1804,7 @@ static void blk_mq_map_swqueue(struct request_queue *q,
 			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;
@@ -1974,56 +1953,93 @@ struct request_queue *blk_mq_init_queue(struct blk_mq_tag_set *set)
 }
 EXPORT_SYMBOL(blk_mq_init_queue);
 
-struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
-						  struct request_queue *q)
+static void blk_mq_realloc_hw_ctxs(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;
+	int i, j;
+	struct blk_mq_hw_ctx **hctxs = q->queue_hw_ctx;
 
+	blk_mq_sysfs_unregister(q);
 	for (i = 0; i < set->nr_hw_queues; i++) {
-		int node = blk_mq_hw_queue_to_node(map, i);
+		int node;
 
+		if (hctxs[i])
+			continue;
+
+		node = blk_mq_hw_queue_to_node(q->mq_map, i);
 		hctxs[i] = kzalloc_node(sizeof(struct blk_mq_hw_ctx),
 					GFP_KERNEL, node);
 		if (!hctxs[i])
-			goto err_hctxs;
+			break;
 
 		if (!zalloc_cpumask_var_node(&hctxs[i]->cpumask, GFP_KERNEL,
-						node))
-			goto err_hctxs;
+						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_rq_map(set, hctx->tags, j);
+				set->tags[j] = NULL;
+			}
+			blk_mq_exit_hctx(q, set, hctx, j);
+			free_cpumask_var(hctx->cpumask);
+			kobject_put(&hctx->kobj);
+			kfree(hctx->ctxs);
+			kfree(hctx);
+			hctxs[j] = NULL;
+
+		}
+	}
+	q->nr_hw_queues = i;
+	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->queue_ctx = alloc_percpu(struct blk_mq_ctx);
+	if (!q->queue_ctx)
+		return ERR_PTR(-ENOMEM);
+
+	q->queue_hw_ctx = kzalloc_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 = blk_mq_make_queue_map(set);
+	if (!q->mq_map)
+		goto err_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->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))
@@ -2050,9 +2066,6 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
 
 	blk_mq_init_cpu_queues(q, set->nr_hw_queues);
 
-	if (blk_mq_init_hw_queues(q, set))
-		goto err_hctxs;
-
 	get_online_cpus();
 	mutex_lock(&all_q_mutex);
 
@@ -2066,17 +2079,11 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,
 	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]);
-	}
+	kfree(q->mq_map);
 err_map:
-	kfree(hctxs);
+	kfree(q->queue_hw_ctx);
 err_percpu:
-	free_percpu(ctx);
+	free_percpu(q->queue_ctx);
 	return ERR_PTR(-ENOMEM);
 }
 EXPORT_SYMBOL(blk_mq_init_allocated_queue);
@@ -2284,9 +2291,13 @@ int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
 		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 = kmalloc_node(set->nr_hw_queues *
-				 sizeof(struct blk_mq_tags *),
+	set->tags = kzalloc_node(nr_cpu_ids * sizeof(struct blk_mq_tags *),
 				 GFP_KERNEL, set->numa_node);
 	if (!set->tags)
 		return -ENOMEM;
@@ -2309,7 +2320,7 @@ void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
 {
 	int i;
 
-	for (i = 0; i < set->nr_hw_queues; i++) {
+	for (i = 0; i < nr_cpu_ids; i++) {
 		if (set->tags[i])
 			blk_mq_free_rq_map(set, set->tags[i], i);
 	}
@@ -2330,6 +2341,8 @@ int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
 
 	ret = 0;
 	queue_for_each_hw_ctx(q, hctx, i) {
+		if (!hctx->tags)
+			continue;
 		ret = blk_mq_tag_update_depth(hctx->tags, nr);
 		if (ret)
 			break;
@@ -2341,6 +2354,35 @@ int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
 	return ret;
 }
 
+void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues)
+{
+	struct request_queue *q;
+
+	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);
+
+	set->nr_hw_queues = nr_hw_queues;
+	list_for_each_entry(q, &set->tag_list, tag_set_list) {
+		blk_mq_realloc_hw_ctxs(set, q);
+
+		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);
+
+		blk_mq_queue_reinit(q, cpu_online_mask);
+	}
+
+	list_for_each_entry(q, &set->tag_list, tag_set_list)
+		blk_mq_unfreeze_queue(q);
+}
+EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues);
+
 void blk_mq_disable_hotplug(void)
 {
 	mutex_lock(&all_q_mutex);
diff --git a/block/blk-mq.h b/block/blk-mq.h
index eaede8e45c9c..9087b11037b7 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -57,6 +57,7 @@ extern int blk_mq_hw_queue_to_node(unsigned int *map, unsigned int);
  */
 extern int blk_mq_sysfs_register(struct request_queue *q);
 extern void blk_mq_sysfs_unregister(struct request_queue *q);
+extern void blk_mq_hctx_kobj_init(struct blk_mq_hw_ctx *hctx);
 
 extern void blk_mq_rq_timed_out(struct request *req, bool reserved);
 
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 1f9093e901da..e3c591dd8f19 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -632,6 +632,13 @@ static inline struct cfq_group *cfqg_parent(struct cfq_group *cfqg)
 	return pblkg ? blkg_to_cfqg(pblkg) : NULL;
 }
 
+static inline bool cfqg_is_descendant(struct cfq_group *cfqg,
+				      struct cfq_group *ancestor)
+{
+	return cgroup_is_descendant(cfqg_to_blkg(cfqg)->blkcg->css.cgroup,
+				    cfqg_to_blkg(ancestor)->blkcg->css.cgroup);
+}
+
 static inline void cfqg_get(struct cfq_group *cfqg)
 {
 	return blkg_get(cfqg_to_blkg(cfqg));
@@ -758,6 +765,11 @@ static void cfqg_stats_xfer_dead(struct cfq_group *cfqg)
 #else	/* CONFIG_CFQ_GROUP_IOSCHED */
 
 static inline struct cfq_group *cfqg_parent(struct cfq_group *cfqg) { return NULL; }
+static inline bool cfqg_is_descendant(struct cfq_group *cfqg,
+				      struct cfq_group *ancestor)
+{
+	return true;
+}
 static inline void cfqg_get(struct cfq_group *cfqg) { }
 static inline void cfqg_put(struct cfq_group *cfqg) { }
 
@@ -2897,6 +2909,7 @@ static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
 {
 	struct cfq_queue *cfqq = cfqd->active_queue;
+	struct cfq_rb_root *st = cfqq->service_tree;
 	struct cfq_io_cq *cic;
 	unsigned long sl, group_idle = 0;
 
@@ -2947,8 +2960,13 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd)
 		return;
 	}
 
-	/* There are other queues in the group, don't do group idle */
-	if (group_idle && cfqq->cfqg->nr_cfqq > 1)
+	/*
+	 * There are other queues in the group or this is the only group and
+	 * it has too big thinktime, don't do group idle.
+	 */
+	if (group_idle &&
+	    (cfqq->cfqg->nr_cfqq > 1 ||
+	     cfq_io_thinktime_big(cfqd, &st->ttime, true)))
 		return;
 
 	cfq_mark_cfqq_wait_request(cfqq);
@@ -3947,16 +3965,27 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
 	if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
 		return true;
 
-	if (new_cfqq->cfqg != cfqq->cfqg)
+	/*
+	 * Treat ancestors of current cgroup the same way as current cgroup.
+	 * For anybody else we disallow preemption to guarantee service
+	 * fairness among cgroups.
+	 */
+	if (!cfqg_is_descendant(cfqq->cfqg, new_cfqq->cfqg))
 		return false;
 
 	if (cfq_slice_used(cfqq))
 		return true;
 
+	/*
+	 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
+	 */
+	if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
+		return true;
+
+	WARN_ON_ONCE(cfqq->ioprio_class != new_cfqq->ioprio_class);
 	/* Allow preemption only if we are idling on sync-noidle tree */
 	if (cfqd->serving_wl_type == SYNC_NOIDLE_WORKLOAD &&
 	    cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
-	    new_cfqq->service_tree->count == 2 &&
 	    RB_EMPTY_ROOT(&cfqq->sort_list))
 		return true;
 
@@ -3967,12 +3996,6 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
 	if ((rq->cmd_flags & REQ_PRIO) && !cfqq->prio_pending)
 		return true;
 
-	/*
-	 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
-	 */
-	if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
-		return true;
-
 	/* An idle queue should not be idle now for some reason */
 	if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq))
 		return true;