locks: fix locks_mandatory_locked to respect file-private locks

As Trond pointed out, you can currently deadlock yourself by setting a
file-private lock on a file that requires mandatory locking and then
trying to do I/O on it.

Avoid this problem by plumbing some knowledge of file-private locks into
the mandatory locking code. In order to do this, we must pass down
information about the struct file that's being used to
locks_verify_locked.

Reported-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Acked-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/fs/namei.c b/fs/namei.c
index d580df2..dc51bac 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2542,7 +2542,7 @@ static int handle_truncate(struct file *filp)
 	/*
 	 * Refuse to truncate files with mandatory locks held on them.
 	 */
-	error = locks_verify_locked(inode);
+	error = locks_verify_locked(filp);
 	if (!error)
 		error = security_path_truncate(path);
 	if (!error) {