md/raid1: If there is a spare and a want_replacement device, start replacement.

When attempting to add a spare to a RAID1 array, also consider
adding it as a replacement for a want_replacement device.

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

1 files changed, 15 insertions, 2 deletions

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 6df0c41578af..e3cfca7cde16 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -1315,8 +1315,9 @@ static int raid1_add_disk(struct mddev *mddev, struct md_rdev *rdev)
         if (rdev->raid_disk >= 0)
                 first = last = rdev->raid_disk;
 
-        for (mirror = first; mirror <= last; mirror++)
-                if ( !(p=conf->mirrors+mirror)->rdev) {
+        for (mirror = first; mirror <= last; mirror++) {
+                p = conf->mirrors+mirror;
+                if (!p->rdev) {
 
                         disk_stack_limits(mddev->gendisk, rdev->bdev,
                                           rdev->data_offset << 9);
@@ -1343,6 +1344,18 @@ static int raid1_add_disk(struct mddev *mddev, struct md_rdev *rdev)
                         rcu_assign_pointer(p->rdev, rdev);
                         break;
                 }
+                if (test_bit(WantReplacement, &p->rdev->flags) &&
+                    p[conf->raid_disks].rdev == NULL) {
+                        /* Add this device as a replacement */
+                        clear_bit(In_sync, &rdev->flags);
+                        set_bit(Replacement, &rdev->flags);
+                        rdev->raid_disk = mirror;
+                        err = 0;
+                        conf->fullsync = 1;
+                        rcu_assign_pointer(p[conf->raid_disks].rdev, rdev);
+                        break;
+                }
+        }
         md_integrity_add_rdev(rdev, mddev);
         print_conf(conf);
         return err;