md: wait for pending superblock updates before switching to read-only

If a superblock update is pending, wait for it to complete before
letting md_set_readonly() switch to readonly.
Otherwise we might lose important information about a device having
failed.

For external arrays, waiting for superblock updates can wait on
user-space, so in that case, just return an error.

Reported-and-tested-by: Shaohua Li <shli@fb.com>
Signed-off-by: NeilBrown <neilb@suse.com>
This commit is contained in:
NeilBrown 2015-09-24 14:00:51 +10:00
parent bcee19f424
commit 88724bfa68

View File

@ -5409,9 +5409,13 @@ static int md_set_readonly(struct mddev *mddev, struct block_device *bdev)
* which will now never happen */
wake_up_process(mddev->sync_thread->tsk);
if (mddev->external && test_bit(MD_CHANGE_PENDING, &mddev->flags))
return -EBUSY;
mddev_unlock(mddev);
wait_event(resync_wait, !test_bit(MD_RECOVERY_RUNNING,
&mddev->recovery));
wait_event(mddev->sb_wait,
!test_bit(MD_CHANGE_PENDING, &mddev->flags));
mddev_lock_nointr(mddev);
mutex_lock(&mddev->open_mutex);