1 files changed, 46 insertions, 3 deletions

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 78ea44336e75..287cc3b30043 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -239,12 +239,47 @@ static void __release_stripe(struct r5conf *conf, struct stripe_head *sh)
 		do_release_stripe(conf, sh);
 }
 
+/* should hold conf->device_lock already */
+static int release_stripe_list(struct r5conf *conf)
+{
+	struct stripe_head *sh;
+	int count = 0;
+	struct llist_node *head;
+
+	head = llist_del_all(&conf->released_stripes);
+	while (head) {
+		sh = llist_entry(head, struct stripe_head, release_list);
+		head = llist_next(head);
+		/* sh could be readded after STRIPE_ON_RELEASE_LIST is cleard */
+		smp_mb();
+		clear_bit(STRIPE_ON_RELEASE_LIST, &sh->state);
+		/*
+		 * Don't worry the bit is set here, because if the bit is set
+		 * again, the count is always > 1. This is true for
+		 * STRIPE_ON_UNPLUG_LIST bit too.
+		 */
+		__release_stripe(conf, sh);
+		count++;
+	}
+
+	return count;
+}
+
 static void release_stripe(struct stripe_head *sh)
 {
 	struct r5conf *conf = sh->raid_conf;
 	unsigned long flags;
+	bool wakeup;
 
+	if (test_and_set_bit(STRIPE_ON_RELEASE_LIST, &sh->state))
+		goto slow_path;
+	wakeup = llist_add(&sh->release_list, &conf->released_stripes);
+	if (wakeup)
+		md_wakeup_thread(conf->mddev->thread);
+	return;
+slow_path:
 	local_irq_save(flags);
+	/* we are ok here if STRIPE_ON_RELEASE_LIST is set or not */
 	if (atomic_dec_and_lock(&sh->count, &conf->device_lock)) {
 		do_release_stripe(conf, sh);
 		spin_unlock(&conf->device_lock);
@@ -491,7 +526,8 @@ get_active_stripe(struct r5conf *conf, sector_t sector,
 			if (atomic_read(&sh->count)) {
 				BUG_ON(!list_empty(&sh->lru)
 				    && !test_bit(STRIPE_EXPANDING, &sh->state)
-				    && !test_bit(STRIPE_ON_UNPLUG_LIST, &sh->state));
+				    && !test_bit(STRIPE_ON_UNPLUG_LIST, &sh->state)
+				    && !test_bit(STRIPE_ON_RELEASE_LIST, &sh->state));
 			} else {
 				if (!test_bit(STRIPE_HANDLE, &sh->state))
 					atomic_inc(&conf->active_stripes);
@@ -4127,6 +4163,10 @@ static void raid5_unplug(struct blk_plug_cb *blk_cb, bool from_schedule)
 			 */
 			smp_mb__before_clear_bit();
 			clear_bit(STRIPE_ON_UNPLUG_LIST, &sh->state);
+			/*
+			 * STRIPE_ON_RELEASE_LIST could be set here. In that
+			 * case, the count is always > 1 here
+			 */
 			__release_stripe(conf, sh);
 			cnt++;
 		}
@@ -4836,7 +4876,9 @@ static void raid5d(struct md_thread *thread)
 	spin_lock_irq(&conf->device_lock);
 	while (1) {
 		struct bio *bio;
-		int batch_size;
+		int batch_size, released;
+
+		released = release_stripe_list(conf);
 
 		if (
 		    !list_empty(&conf->bitmap_list)) {
@@ -4861,7 +4903,7 @@ static void raid5d(struct md_thread *thread)
 		}
 
 		batch_size = handle_active_stripes(conf);
-		if (!batch_size)
+		if (!batch_size && !released)
 			break;
 		handled += batch_size;
 
@@ -5176,6 +5218,7 @@ static struct r5conf *setup_conf(struct mddev *mddev)
 	INIT_LIST_HEAD(&conf->delayed_list);
 	INIT_LIST_HEAD(&conf->bitmap_list);
 	INIT_LIST_HEAD(&conf->inactive_list);
+	init_llist_head(&conf->released_stripes);
 	atomic_set(&conf->active_stripes, 0);
 	atomic_set(&conf->preread_active_stripes, 0);
 	atomic_set(&conf->active_aligned_reads, 0);