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/multipath.c b/drivers/md/multipath.c
index e968116e0de9..4a1d714c048e 100644
--- a/drivers/md/multipath.c
+++ b/drivers/md/multipath.c
@@ -284,10 +284,15 @@ static int multipath_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
         int found = 0;
         int path;
         struct multipath_info *p;
+        int first = 0;
+        int last = mddev->raid_disks - 1;
+
+        if (rdev->raid_disk >= 0)
+                first = last = rdev->raid_disk;
 
         print_multipath_conf(conf);
 
-        for (path=0; path<mddev->raid_disks; path++) 
+        for (path = first; path <= last; path++)
                 if ((p=conf->multipaths+path)->rdev == NULL) {
                         q = rdev->bdev->bd_disk->queue;
                         blk_queue_stack_limits(mddev->queue, q);