md: allow a partially recovered device to be hot-added to an array.
When adding a new device into an array it is normally important to
clear any stale data from ->recovery_offset else the new device may
not be recovered properly.
However when re-adding a device which is known to be nearly in-sync,
this is not needed and can be detrimental. The (bitmap-based)
resync will still happen, and further recovery is only needed from
where-ever it was already up to.
So if save_raid_disk is set, signifying a re-add, don't clear
->recovery_offset.
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 539f088..757e388 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -7736,7 +7736,8 @@
!test_bit(Bitmap_sync, &rdev->flags)))
continue;
- rdev->recovery_offset = 0;
+ if (rdev->saved_raid_disk < 0)
+ rdev->recovery_offset = 0;
if (mddev->pers->
hot_add_disk(mddev, rdev) == 0) {
if (sysfs_link_rdev(mddev, rdev))