[PATCH 4.1 68/86] Revert "md: allow a partially recovered device to be hot-added to an array."

Greg Kroah-Hartman
2015-11-06T20:01:57Z

From: NeilBrown <neilb@suse.com>

commit d01552a76d71f9879af448e9142389ee9be6e95b upstream.

This reverts commit 7eb418851f3278de67126ea0c427641ab4792c57.

This commit is poorly justified, I can find not discusison in email,
and it clearly causes a problem.

If a device which is being recovered fails and is subsequently
re-added to an array, there could easily have been changes to the
array *before* the point where the recovery was up to. So the
recovery must start again from the beginning.

If a spare is being recovered and fails, then when it is re-added we
really should do a bitmap-based recovery up to the recovery-offset,
and then a full recovery from there. Before this reversion, we only
did the "full recovery from there" which is not corect. After this
reversion with will do a full recovery from the start, which is safer
but not ideal.

It will be left to a future patch to arrange the two different styles
of recovery.

Reported-and-tested-by: Nate Dailey <nate.dailey@stratus.com>
Signed-off-by: NeilBrown <neilb@suse.com>
Fixes: 7eb418851f32 ("md: allow a partially recovered device to be hot-added to an array.")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/md/md.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -8013,8 +8013,7 @@ static int remove_and_add_spares(struct
!test_bit(Bitmap_sync, &rdev->flags)))
continue;

- if (rdev->saved_raid_disk < 0)
- rdev->recovery_offset = 0;
+ rdev->recovery_offset = 0;
if (mddev->pers->
hot_add_disk(mddev, rdev) == 0) {
if (sysfs_link_rdev(mddev, rdev))