linux-kernel - [PATCH 3.13 088/212] md: avoid possible spinning md thread at shutdown.

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Message-Id: <1403041506-13646-89-git-send-email-kamal@canonical.com>
Date:	Tue, 17 Jun 2014 14:43:02 -0700
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.de>, Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 3.13 088/212] md: avoid possible spinning md thread at shutdown.

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

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

From: NeilBrown <neilb@...e.de>

commit 0f62fb220aa4ebabe8547d3a9ce4a16d3c045f21 upstream.

If an md array with externally managed metadata (e.g. DDF or IMSM)
is in use, then we should not set safemode==2 at shutdown because:

1/ this is ineffective: user-space need to be involved in any 'safemode' handling,
2/ The safemode management code doesn't cope with safemode==2 on external metadata
   and md_check_recover enters an infinite loop.

Even at shutdown, an infinite-looping process can be problematic, so this
could cause shutdown to hang.

Signed-off-by: NeilBrown <neilb@...e.de>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 drivers/md/md.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 369d919..ddb71d8 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -8496,7 +8496,8 @@ static int md_notify_reboot(struct notifier_block *this,
 		if (mddev_trylock(mddev)) {
 			if (mddev->pers)
 				__md_stop_writes(mddev);
-			mddev->safemode = 2;
+			if (mddev->persistent)
+				mddev->safemode = 2;
 			mddev_unlock(mddev);
 		}
 		need_delay = 1;
-- 
1.9.1

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