On Wed, Nov 25, 2020 at 01:29:53PM +0100, Jan Kara wrote:

quoted

 	mutex_unlock(&bdev->bd_fsfreeze_mutex);
-	return sb;	/* thaw_bdev releases s->s_umount */
+	return error;	/* thaw_bdev releases s->s_umount */

The comment about thaw_bdev() seems to be stale? At least I don't see what
it's speaking about...

Yes, this comment seems long stale.  I think in the very early days
we held s_umount on frozen file system, which caused all kinds of
problems.

quoted

 	mutex_unlock(&bdev->bd_fsfreeze_mutex);
-	return error;
+	return 0;

But we now won't return -EINVAL if this gets called e.g. with
bd_fsfreeze_count == 0, right?

Yes.  I had tried to drop the return value as all the freeze_bdev
calls ignored it.  But I had missed the unpaired emergency thaw and put
it back and messed this up..