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, 6 insertions, 1 deletions

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index c610b947218a..d32fc559ff05 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -1103,8 +1103,13 @@ static int raid1_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
         int found = 0;
         int mirror = 0;
         mirror_info_t *p;
+        int first = 0;
+        int last = mddev->raid_disks - 1;
 
-        for (mirror=0; mirror < mddev->raid_disks; mirror++)
+        if (rdev->raid_disk >= 0)
+                first = last = rdev->raid_disk;
+
+        for (mirror = first; mirror <= last; mirror++)
                 if ( !(p=conf->mirrors+mirror)->rdev) {
 
                         blk_queue_stack_limits(mddev->queue,