fs/block_dev.c: return the right error in thaw_bdev()

When triggering thaw-filesystems via magic sysrq, the system enters a
loop in do_thaw_one(), as thaw_bdev() still returns success if
bd_fsfreeze_count == 0. To fix this, let thaw_bdev() always return
error (and simplify the code a bit at the same time).

Reviewed-by: Eric Farman <[email protected]>
Reviewed-by: Cornelia Huck <[email protected]>
Signed-off-by: Pierre Morel <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>

Author: Pierre Morel

fs/block_dev.c

@@ -299,14 +299,11 @@ int thaw_bdev(struct block_device *bdev, struct super_block *sb)
 		error = sb->s_op->thaw_super(sb);
 	else
 		error = thaw_super(sb);
-	if (error) {
+	if (error)
 		bdev->bd_fsfreeze_count++;
-		mutex_unlock(&bdev->bd_fsfreeze_mutex);
-		return error;
-	}
 out:
 	mutex_unlock(&bdev->bd_fsfreeze_mutex);
-	return 0;
+	return error;
 }
 EXPORT_SYMBOL(thaw_bdev);