9p: do not overwrite return code when locking fails

If the remote locking fail, we run a local vfs unlock that should work and
return success to userland when we didn't actually lock at all.  We need
to tell the application that tried to lock that it didn't get it, not that
all went well.
Signed-off-by: Dominique Martinet <dominique.martinet@cea.fr>
Cc: Eric Van Hensbergen <ericvh@gmail.com>
Cc: Ron Minnich <rminnich@sandia.gov>
Cc: Latchesar Ionkov <lucho@ionkov.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/9p/vfs_file.c

@@ -231,7 +231,8 @@ static int v9fs_file_do_lock(struct file *filp, int cmd, struct file_lock *fl)
 	if (res < 0 && fl->fl_type != F_UNLCK) {
 		fl_type = fl->fl_type;
 		fl->fl_type = F_UNLCK;
-		res = posix_lock_file_wait(filp, fl);
+		/* Even if this fails we want to return the remote error */
+		posix_lock_file_wait(filp, fl);
 		fl->fl_type = fl_type;
 	}
 out: