With the current implementation, blocking flock can lead to
deadlock. Thus, it's better to return EOPNOTSUPP if a user attempts
to perform a blocking flock request.
Signed-off-by: Sebastian Hasler <sebastian.hasler@stuvus.uni-stuttgart.de>
Message-Id: <
20220113153249.710216-1-sebastian.hasler@stuvus.uni-stuttgart.de>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
int res;
(void)ino;
+ if (!(op & LOCK_NB)) {
+ /*
+ * Blocking flock can deadlock as there is only one thread
+ * serving the queue.
+ */
+ fuse_reply_err(req, EOPNOTSUPP);
+ return;
+ }
+
res = flock(lo_fi_fd(req, fi), op);
fuse_reply_err(req, res == -1 ? errno : 0);