[PATCH 3.14 31/37] Revert "md: allow a partially recovered device to be hot-added to an array."

From: Greg Kroah-Hartman
Date: Fri Nov 06 2015 - 14:55:17 EST

3.14-stable review patch. If anyone has any objections, please let me know.


From: NeilBrown <neilb@xxxxxxxx>

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@xxxxxxxxxxx>
Signed-off-by: NeilBrown <neilb@xxxxxxxx>
Fixes: 7eb418851f32 ("md: allow a partially recovered device to be hot-added to an array.")
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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

--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -7775,8 +7775,7 @@ static int remove_and_add_spares(struct
!test_bit(Bitmap_sync, &rdev->flags)))

- 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))

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