1 files changed, 42 insertions, 29 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 796cf70e1c9f..788559f42d43 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -147,28 +147,40 @@ static void rdevs_init_serial(struct mddev *mddev)
 }
 
 /*
- * Create serial_info_pool for raid1 under conditions:
- * 1. rdev is the first multi-queue device flaged with writemostly,
- *    also write-behind mode is enabled.
- * 2. rdev is NULL, means want to enable serialization for all rdevs.
+ * rdev needs to enable serial stuffs if it meets the conditions:
+ * 1. it is multi-queue device flaged with writemostly.
+ * 2. the write-behind mode is enabled.
+ */
+static int rdev_need_serial(struct md_rdev *rdev)
+{
+	return (rdev && rdev->mddev->bitmap_info.max_write_behind > 0 &&
+		rdev->bdev->bd_queue->nr_hw_queues != 1 &&
+		test_bit(WriteMostly, &rdev->flags));
+}
+
+/*
+ * Init resource for rdev(s), then create serial_info_pool if:
+ * 1. rdev is the first device which return true from rdev_enable_serial.
+ * 2. rdev is NULL, means we want to enable serialization for all rdevs.
  */
 void mddev_create_serial_pool(struct mddev *mddev, struct md_rdev *rdev,
 			      bool is_suspend)
 {
-	if (rdev && (mddev->bitmap_info.max_write_behind == 0 ||
-		     rdev->bdev->bd_queue->nr_hw_queues == 1 ||
-		     !test_bit(WriteMostly, &rdev->flags)))
+	if (rdev && !rdev_need_serial(rdev) &&
+	    !test_bit(CollisionCheck, &rdev->flags))
 		return;
 
+	if (!is_suspend)
+		mddev_suspend(mddev);
+
+	if (!rdev)
+		rdevs_init_serial(mddev);
+	else
+		rdev_init_serial(rdev);
+
 	if (mddev->serial_info_pool == NULL) {
 		unsigned int noio_flag;
 
-		if (!is_suspend)
-			mddev_suspend(mddev);
-		if (!rdev)
-			rdevs_init_serial(mddev);
-		else
-			rdev_init_serial(rdev);
 		noio_flag = memalloc_noio_save();
 		mddev->serial_info_pool =
 			mempool_create_kmalloc_pool(NR_SERIAL_INFOS,
@@ -176,15 +188,16 @@ void mddev_create_serial_pool(struct mddev *mddev, struct md_rdev *rdev,
 		memalloc_noio_restore(noio_flag);
 		if (!mddev->serial_info_pool)
 			pr_err("can't alloc memory pool for serialization\n");
-		if (!is_suspend)
-			mddev_resume(mddev);
 	}
+	if (!is_suspend)
+		mddev_resume(mddev);
 }
 
 /*
- * Destroy serial_info_pool if rdev is the last device flaged with
- * CollisionCheck, or rdev is NULL when we disable serialization
- * for normal raid1.
+ * Free resource from rdev(s), and destroy serial_info_pool under conditions:
+ * 1. rdev is the last device flaged with CollisionCheck.
+ * 2. when bitmap is destroyed while policy is not enabled.
+ * 3. for disable policy, the pool is destroyed only when no rdev needs it.
  */
 static void mddev_destroy_serial_pool(struct mddev *mddev, struct md_rdev *rdev,
 				      bool is_suspend)
@@ -194,27 +207,27 @@ static void mddev_destroy_serial_pool(struct mddev *mddev, struct md_rdev *rdev,
 
 	if (mddev->serial_info_pool) {
 		struct md_rdev *temp;
-		int num = 0;
+		int num = 0; /* used to track if other rdevs need the pool */
 
-		/*
-		 * Check if other rdevs need serial_info_pool.
-		 */
 		if (!is_suspend)
 			mddev_suspend(mddev);
 		rdev_for_each(temp, mddev) {
 			if (!rdev) {
-				clear_bit(CollisionCheck, &temp->flags);
-				continue;
-			}
-
-			if (temp != rdev &&
-			    test_bit(CollisionCheck, &temp->flags))
+				if (!rdev_need_serial(temp))
+					clear_bit(CollisionCheck, &temp->flags);
+				else
+					num++;
+			} else if (temp != rdev &&
+				   test_bit(CollisionCheck, &temp->flags))
 				num++;
 		}
 
 		if (rdev)
 			clear_bit(CollisionCheck, &rdev->flags);
-		if (!rdev || !num) {
+
+		if (num)
+			pr_info("The mempool could be used by other devices\n");
+		else {
 			mempool_destroy(mddev->serial_info_pool);
 			mddev->serial_info_pool = NULL;
 		}