md: enable raid4->raid0 takeover

Only level 5 with layout=PARITY_N can be taken over to raid0 now.
Lets allow level 4 either.

Signed-off-by: Maciej Trela <maciej.trela@intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>

1 files changed, 6 insertions, 2 deletions

diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
index ac09b7d38553..563abed5a2cb 100644
--- a/drivers/md/raid0.c
+++ b/drivers/md/raid0.c
@@ -569,7 +569,7 @@ static void raid0_status(struct seq_file *seq, mddev_t *mddev)
         return;
 }
 
-static void *raid0_takeover_raid5(mddev_t *mddev)
+static void *raid0_takeover_raid45(mddev_t *mddev)
 {
         mdk_rdev_t *rdev;
         raid0_conf_t *priv_conf;
@@ -647,12 +647,16 @@ static void *raid0_takeover_raid10(mddev_t *mddev)
 static void *raid0_takeover(mddev_t *mddev)
 {
         /* raid0 can take over:
+         *  raid4 - if all data disks are active.
          *  raid5 - providing it is Raid4 layout and one disk is faulty
          *  raid10 - assuming we have all necessary active disks
          */
+        if (mddev->level == 4)
+                return raid0_takeover_raid45(mddev);
+
         if (mddev->level == 5) {
                 if (mddev->layout == ALGORITHM_PARITY_N)
-                        return raid0_takeover_raid5(mddev);
+                        return raid0_takeover_raid45(mddev);
 
                 printk(KERN_ERR "md/raid0:%s: Raid can only takeover Raid5 with layout: %d\n",
                        mdname(mddev), ALGORITHM_PARITY_N);