cifs: potential missing check for posix_lock_file_wait

posix_lock_file_wait may fail under certain circumstances, and its result is
usually checked/returned. But given the complexity of cifs, I'm not sure if
the result is intentially left unchecked and always expected to succeed.
Signed-off-by: NChengyu Song <csong84@gatech.edu>
Acked-by: NJeff Layton <jeff.layton@primarydata.com>
Signed-off-by: NSteve French <smfrench@gmail.com>

fs/cifs/file.c

@@ -1552,8 +1552,8 @@ cifs_setlk(struct file *file, struct file_lock *flock, __u32 type,
 		rc = server->ops->mand_unlock_range(cfile, flock, xid);
 
 out:
-	if (flock->fl_flags & FL_POSIX)
-		posix_lock_file_wait(file, flock);
+	if (flock->fl_flags & FL_POSIX && !rc)
+		rc = posix_lock_file_wait(file, flock);
 	return rc;
 }