[PATCH 2/2] 9p: do not crash on unknown lock status code

["Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>]

Current 9p implementation will crash whole system if sees unkown lock
status code. It's trivial target for DOS: 9p server can produce such
code easily.

Let's fallback more gracefully: warning in dmesg + -ENOLCK.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 fs/9p/vfs_file.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index 8d29e1e03dfa..0db033e698eb 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -212,12 +212,13 @@ static int v9fs_file_do_lock(struct file *filp, int cmd, struct file_lock *fl)
 	case P9_LOCK_BLOCKED:
 		res = -EAGAIN;
 		break;
+	default:
+		WARN_ONCE(1, "unknown lock status clode: %d\n", status);
+		/* fallthough */
 	case P9_LOCK_ERROR:
 	case P9_LOCK_GRACE:
 		res = -ENOLCK;
 		break;
-	default:
-		BUG();
 	}
 
 out_unlock:
-- 
2.1.4