From: NeilBrown Date: Tue, 24 Apr 2012 00:23:16 +0000 (+1000) Subject: md: fix possible corruption of array metadata on shutdown. X-Git-Url: http://git.alex.org.uk md: fix possible corruption of array metadata on shutdown. BugLink: http://bugs.launchpad.net/bugs/992038 commit c744a65c1e2d59acc54333ce8 md: don't set md arrays to readonly on shutdown. removed the possibility of a 'BUG' when data is written to an array that has just been switched to read-only, but also introduced the possibility that the array metadata could be corrupted. If, when md_notify_reboot gets the mddev lock, the array is in a state where it is assembled but hasn't been started (as can happen if the personality module is not available, or in other unusual situations), then incorrect metadata will be written out making it impossible to re-assemble the array. So only call __md_stop_writes() if the array has actually been activated. This patch is needed for any stable kernel which has had the above commit applied. Cc: stable@vger.kernel.org Reported-by: Christoph Nelles Signed-off-by: NeilBrown (cherry picked from commit 30b8aa9172dfeaac6d77897c67ee9f9fc574cdbb) Signed-off-by: Luis Henriques Acked-by: Seth Forshee Signed-off-by: Tim Gardner --- diff --git a/drivers/md/md.c b/drivers/md/md.c index 6f37aa4..065ab4f 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -8100,7 +8100,8 @@ static int md_notify_reboot(struct notifier_block *this, for_each_mddev(mddev, tmp) { if (mddev_trylock(mddev)) { - __md_stop_writes(mddev); + if (mddev->pers) + __md_stop_writes(mddev); mddev->safemode = 2; mddev_unlock(mddev); }