[PATCH 4.9 081/240] md: factor out a mddev_find_locked helper from mddev_find

[Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>]

From: Christoph Hellwig <hch@xxxxxx>

commit 8b57251f9a91f5e5a599de7549915d2d226cc3af upstream.

Factor out a self-contained helper to just lookup a mddev by the dev_t
"unit".

Cc: stable@xxxxxxxxxxxxxxx
Reviewed-by: Heming Zhao <heming.zhao@xxxxxxxx>
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Song Liu <song@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/md/md.c |   32 +++++++++++++++++++-------------
 1 file changed, 19 insertions(+), 13 deletions(-)

--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -508,6 +508,17 @@ void mddev_init(struct mddev *mddev)
 }
 EXPORT_SYMBOL_GPL(mddev_init);
 
+static struct mddev *mddev_find_locked(dev_t unit)
+{
+	struct mddev *mddev;
+
+	list_for_each_entry(mddev, &all_mddevs, all_mddevs)
+		if (mddev->unit == unit)
+			return mddev;
+
+	return NULL;
+}
+
 static struct mddev *mddev_find(dev_t unit)
 {
 	struct mddev *mddev, *new = NULL;
@@ -519,13 +530,13 @@ static struct mddev *mddev_find(dev_t un
 	spin_lock(&all_mddevs_lock);
 
 	if (unit) {
-		list_for_each_entry(mddev, &all_mddevs, all_mddevs)
-			if (mddev->unit == unit) {
-				mddev_get(mddev);
-				spin_unlock(&all_mddevs_lock);
-				kfree(new);
-				return mddev;
-			}
+		mddev = mddev_find_locked(unit);
+		if (mddev) {
+			mddev_get(mddev);
+			spin_unlock(&all_mddevs_lock);
+			kfree(new);
+			return mddev;
+		}
 
 		if (new) {
 			list_add(&new->all_mddevs, &all_mddevs);
@@ -551,12 +562,7 @@ static struct mddev *mddev_find(dev_t un
 				return NULL;
 			}
 
-			is_free = 1;
-			list_for_each_entry(mddev, &all_mddevs, all_mddevs)
-				if (mddev->unit == dev) {
-					is_free = 0;
-					break;
-				}
+			is_free = !mddev_find_locked(dev);
 		}
 		new->unit = dev;
 		new->md_minor = MINOR(dev);