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>
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 4f5ecbe..b8247bc 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -5409,9 +5409,13 @@
* 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);
