lockd: server should unlock lock if client rejects the grant

Currently lockd just dequeues the block and ignores it if the client
sends a GRANT_RES with a status of nlm_lck_denied. That status is an
indicator that the client has rejected the lock, so the right thing to
do is to unlock the lock we were trying to grant.

Reported-by: Yongcheng Yang <[email protected]>
Link: https://bugzilla.redhat.com/show_bug.cgi?id=2063818
Signed-off-by: Jeff Layton <[email protected]>
Signed-off-by: Chuck Lever <[email protected]>

fs/lockd/svclock.c

@@ -954,19 +954,32 @@ void
 nlmsvc_grant_reply(struct nlm_cookie *cookie, __be32 status)
 {
  struct nlm_block *block;
+ struct file_lock *fl;
+ int error;
 
  dprintk("grant_reply: looking for cookie %x, s=%d \n",
  *(unsigned int *)(cookie->data), status);
  if (!(block = nlmsvc_find_block(cookie)))
  return;
 
- if (status == nlm_lck_denied_grace_period) {
+ switch (status) {
+ case nlm_lck_denied_grace_period:
  /* Try again in a couple of seconds */
  nlmsvc_insert_block(block, 10 * HZ);
- } else {
+ break;
+ case nlm_lck_denied:
+ /* Client doesn't want it, just unlock it */
+ nlmsvc_unlink_block(block);
+ fl = &block->b_call->a_args.lock.fl;
+ fl->fl_type = F_UNLCK;
+ error = vfs_lock_file(fl->fl_file, F_SETLK, fl, NULL);
+ if (error)
+ pr_warn("lockd: unable to unlock lock rejected by client!\n");
+ break;
+ default:
  /*
- * Lock is now held by client, or has been rejected.
- * In both cases, the block should be removed.
+ * Either it was accepted or the status makes no sense
+ * just unlink it either way.
  */
  nlmsvc_unlink_block(block);
  }