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>

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 2882a26646fdc74f13cf50b8a2458d7829e3f787..81563b7c03571b2b8a629a4a8054b79d1130310f 100644 (file)
--- 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;