md/raid4: permit raid0 takeover

For consistency allow raid4 to takeover raid0 in addition to raid5 (with a
raid4 layout).

Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 17 insertions, 15 deletions

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 2882a26646fd..81563b7c0357 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -5610,10 +5610,17 @@ static void raid5_quiesce(mddev_t *mddev, int state)
 }
 
 
-static void *raid5_takeover_raid0(mddev_t *mddev)
+static void *raid45_takeover_raid0(mddev_t *mddev, int level)
 {
+        struct raid0_private_data *raid0_priv = mddev->private;
 
-        mddev->new_level = 5;
+        /* for raid0 takeover only one zone is supported */
+        if (raid0_priv->nr_strip_zones > 1) {
+                printk(KERN_ERR "md: cannot takeover raid0 with more than one zone.\n");
+                return ERR_PTR(-EINVAL);
+        }
+
+        mddev->new_level = level;
         mddev->new_layout = ALGORITHM_PARITY_N;
         mddev->new_chunk_sectors = mddev->chunk_sectors;
         mddev->raid_disks += 1;
@@ -5749,22 +5756,13 @@ static int raid6_check_reshape(mddev_t *mddev)
 static void *raid5_takeover(mddev_t *mddev)
 {
         /* raid5 can take over:
-         *  raid0 - if all devices are the same - make it a raid4 layout
+         *  raid0 - if there is only one strip zone - make it a raid4 layout
          *  raid1 - if there are two drives.  We need to know the chunk size
          *  raid4 - trivial - just use a raid4 layout.
          *  raid6 - Providing it is a *_6 layout
          */
-        if (mddev->level == 0) {
-                /* for raid0 takeover only one zone is supported */
-                struct raid0_private_data *raid0_priv
-                        = mddev->private;
-                if (raid0_priv->nr_strip_zones > 1) {
-                        printk(KERN_ERR "md: cannot takeover raid 0 with more than one zone.\n");
-                        return ERR_PTR(-EINVAL);
-                }
-                return raid5_takeover_raid0(mddev);
-        }
-
+        if (mddev->level == 0)
+                return raid45_takeover_raid0(mddev, 5);
         if (mddev->level == 1)
                 return raid5_takeover_raid1(mddev);
         if (mddev->level == 4) {
@@ -5780,8 +5778,12 @@ static void *raid5_takeover(mddev_t *mddev)
 
 static void *raid4_takeover(mddev_t *mddev)
 {
-        /* raid4 can take over raid5 if layout is right.
+        /* raid4 can take over:
+         *  raid0 - if there is only one strip zone
+         *  raid5 - if layout is right
          */
+        if (mddev->level == 0)
+                return raid45_takeover_raid0(mddev, 4);
         if (mddev->level == 5 &&
             mddev->layout == ALGORITHM_PARITY_N) {
                 mddev->new_layout = 0;