Add raid1->raid0 takeover support

This patch introduces raid 1 to raid0 takeover operation
in kernel space.

Signed-off-by: Krzysztof Wojcik <krzysztof.wojcik@intel.com>
Signed-off-by: Neil Brown <neilb@nbeee.brown>

1 files changed, 40 insertions, 0 deletions

diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
index a39f4c355e55..637a96855edb 100644
--- a/drivers/md/raid0.c
+++ b/drivers/md/raid0.c
@@ -179,6 +179,14 @@ static int create_strip_zones(mddev_t *mddev, raid0_conf_t **private_conf)
                         rdev1->new_raid_disk = j;
                 }
 
+                if (mddev->level == 1) {
+                        /* taiking over a raid1 array-
+                         * we have only one active disk
+                         */
+                        j = 0;
+                        rdev1->new_raid_disk = j;
+                }
+
                 if (j < 0 || j >= mddev->raid_disks) {
                         printk(KERN_ERR "md/raid0:%s: bad disk number %d - "
                                "aborting!\n", mdname(mddev), j);
@@ -644,12 +652,38 @@ static void *raid0_takeover_raid10(mddev_t *mddev)
         return priv_conf;
 }
 
+static void *raid0_takeover_raid1(mddev_t *mddev)
+{
+        raid0_conf_t *priv_conf;
+
+        /* Check layout:
+         *  - (N - 1) mirror drives must be already faulty
+         */
+        if ((mddev->raid_disks - 1) != mddev->degraded) {
+                printk(KERN_ERR "md/raid0:%s: (N - 1) mirrors drives must be already faulty!\n",
+                       mdname(mddev));
+                return ERR_PTR(-EINVAL);
+        }
+
+        /* Set new parameters */
+        mddev->new_level = 0;
+        mddev->new_layout = 0;
+        mddev->new_chunk_sectors = 128; /* by default set chunk size to 64k */
+        mddev->delta_disks = 1 - mddev->raid_disks;
+        /* make sure it will be not marked as dirty */
+        mddev->recovery_cp = MaxSector;
+
+        create_strip_zones(mddev, &priv_conf);
+        return priv_conf;
+}
+
 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
+         *  raid1 - with (N -1) mirror drives faulty
          */
         if (mddev->level == 4)
                 return raid0_takeover_raid45(mddev);
@@ -665,6 +699,12 @@ static void *raid0_takeover(mddev_t *mddev)
         if (mddev->level == 10)
                 return raid0_takeover_raid10(mddev);
 
+        if (mddev->level == 1)
+                return raid0_takeover_raid1(mddev);
+
+        printk(KERN_ERR "Takeover from raid%i to raid0 not supported\n",
+                mddev->level);
+
         return ERR_PTR(-EINVAL);
 }