lockd: Fix Oopses due to list manipulation errors.

The patch "stop abusing file_lock_list introduces a couple of bugs since
the locks may be copied and need to be removed from the lists when they are
destroyed.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/lockd/clntlock.c

@@ -213,11 +213,12 @@ reclaimer(void *ptr)
 	/* First, reclaim all locks that have been marked. */
 restart:
 	list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) {
-		list_del(&fl->fl_u.nfs_fl.list);
+		list_del_init(&fl->fl_u.nfs_fl.list);
 
-		nlmclnt_reclaim(host, fl);
 		if (signalled())
-			break;
+			continue;
+		if (nlmclnt_reclaim(host, fl) == 0)
+			list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted);
 		goto restart;
 	}
 

fs/lockd/clntproc.c

@@ -446,12 +446,14 @@ nlmclnt_test(struct nlm_rqst *req, struct file_lock *fl)
 
 static void nlmclnt_locks_copy_lock(struct file_lock *new, struct file_lock *fl)
 {
-	memcpy(&new->fl_u.nfs_fl, &fl->fl_u.nfs_fl, sizeof(new->fl_u.nfs_fl));
-	nlm_get_lockowner(new->fl_u.nfs_fl.owner);
+	new->fl_u.nfs_fl.state = fl->fl_u.nfs_fl.state;
+	new->fl_u.nfs_fl.owner = nlm_get_lockowner(fl->fl_u.nfs_fl.owner);
+	list_add_tail(&new->fl_u.nfs_fl.list, &fl->fl_u.nfs_fl.owner->host->h_granted);
 }
 
 static void nlmclnt_locks_release_private(struct file_lock *fl)
 {
+	list_del(&fl->fl_u.nfs_fl.list);
 	nlm_put_lockowner(fl->fl_u.nfs_fl.owner);
 	fl->fl_ops = NULL;
 }
@@ -466,6 +468,7 @@ static void nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *ho
 	BUG_ON(fl->fl_ops != NULL);
 	fl->fl_u.nfs_fl.state = 0;
 	fl->fl_u.nfs_fl.owner = nlm_find_lockowner(host, fl->fl_owner);
+	INIT_LIST_HEAD(&fl->fl_u.nfs_fl.list);
 	fl->fl_ops = &nlmclnt_lock_ops;
 }
 
@@ -552,7 +555,7 @@ nlmclnt_lock(struct nlm_rqst *req, struct file_lock *fl)
 	if (resp->status == NLM_LCK_GRANTED) {
 		fl->fl_u.nfs_fl.state = host->h_state;
 		fl->fl_flags |= FL_SLEEP;
-		list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted);
+		/* Ensure the resulting lock will get added to granted list */
 		do_vfs_lock(fl);
 	}
 	status = nlm_stat_to_errno(resp->status);
@@ -618,12 +621,6 @@ nlmclnt_unlock(struct nlm_rqst *req, struct file_lock *fl)
 	struct nlm_res	*resp = &req->a_res;
 	int		status;
 
-	/*
-	 * Remove from the granted list now so the lock doesn't get
-	 * reclaimed while we're stuck in the unlock call.
-	 */
-	list_del(&fl->fl_u.nfs_fl.list);
-
 	/*
 	 * Note: the server is supposed to either grant us the unlock
 	 * request, or to deny it with NLM_LCK_DENIED_GRACE_PERIOD. In either

fs/lockd/host.c

@@ -245,8 +245,12 @@ void nlm_release_host(struct nlm_host *host)
 {
 	if (host != NULL) {
 		dprintk("lockd: release host %s\n", host->h_name);
-		atomic_dec(&host->h_count);
 		BUG_ON(atomic_read(&host->h_count) < 0);
+		if (atomic_dec_and_test(&host->h_count)) {
+			BUG_ON(!list_empty(&host->h_lockowners));
+			BUG_ON(!list_empty(&host->h_granted));
+			BUG_ON(!list_empty(&host->h_reclaim));
+		}
 	}
 }
 
@@ -334,7 +338,6 @@ nlm_gc_hosts(void)
 					rpc_destroy_client(host->h_rpcclnt);
 				}
 			}
-			BUG_ON(!list_empty(&host->h_lockowners));
 			kfree(host);
 			nrhosts--;
 		}