linux-kernel - [PATCH 3.19.y-ckt 151/155] Revert "md: allow a partially recovered device to be hot-added to an array."

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Message-Id: <1447370309-357-152-git-send-email-kamal@canonical.com>
Date:	Thu, 12 Nov 2015 15:18:25 -0800
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	NeilBrown <neilb@...e.com>, Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 3.19.y-ckt 151/155] Revert "md: allow a partially recovered device to be hot-added to an array."

3.19.8-ckt10 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: NeilBrown <neilb@...e.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@...atus.com>
Signed-off-by: NeilBrown <neilb@...e.com>
Fixes: 7eb418851f32 ("md: allow a partially recovered device to be hot-added to an array.")
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 drivers/md/md.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index d7f0a56..6b82962 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -7575,8 +7575,7 @@ static int remove_and_add_spares(struct mddev *mddev,
 		       !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))
-- 
1.9.1

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