Support adding a spare to a live md array with external metadata.

i.e. extend the 'md/dev-XXX/slot' attribute so that you can
tell a device to fill an vacant slot in an and md array.

Signed-off-by: Neil Brown <neilb@suse.de>

1 files changed, 8 insertions, 2 deletions

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index a71277b640ab..50ad8d2ae0e8 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -1116,6 +1116,8 @@ static int raid10_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
         int found = 0;
         int mirror;
         mirror_info_t *p;
+        int first = 0;
+        int last = mddev->raid_disks - 1;
 
         if (mddev->recovery_cp < MaxSector)
                 /* only hot-add to in-sync arrays, as recovery is
@@ -1125,12 +1127,16 @@ static int raid10_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
         if (!enough(conf))
                 return 0;
 
+        if (rdev->raid_disk)
+                first = last = rdev->raid_disk;
+
         if (rdev->saved_raid_disk >= 0 &&
+            rdev->saved_raid_disk >= first &&
             conf->mirrors[rdev->saved_raid_disk].rdev == NULL)
                 mirror = rdev->saved_raid_disk;
         else
-                mirror = 0;
-        for ( ; mirror < mddev->raid_disks; mirror++)
+                mirror = first;
+        for ( ; mirror <= last ; mirror++)
                 if ( !(p=conf->mirrors+mirror)->rdev) {
 
                         blk_queue_stack_limits(mddev->queue,