btrfs: fix error handling in __btrfs_update_delayed_inode

[ Upstream commit bb385be ]

If we get an error while looking up the inode item we'll simply bail
without cleaning up the delayed node.  This results in this style of
warning happening on commit:

  WARNING: CPU: 0 PID: 76403 at fs/btrfs/delayed-inode.c:1365 btrfs_assert_delayed_root_empty+0x5b/0x90
  CPU: 0 PID: 76403 Comm: fsstress Tainted: G        W         5.13.0-rc1+ #373
  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-2.fc32 04/01/2014
  RIP: 0010:btrfs_assert_delayed_root_empty+0x5b/0x90
  RSP: 0018:ffffb8bb815a7e50 EFLAGS: 00010286
  RAX: 0000000000000000 RBX: ffff95d6d07e1888 RCX: ffff95d6c0fa3000
  RDX: 0000000000000002 RSI: 000000000029e91c RDI: ffff95d6c0fc8060
  RBP: ffff95d6c0fc8060 R08: 00008d6d701a2c1d R09: 0000000000000000
  R10: ffff95d6d1760ea0 R11: 0000000000000001 R12: ffff95d6c15a4d00
  R13: ffff95d6c0fa3000 R14: 0000000000000000 R15: ffffb8bb815a7e90
  FS:  00007f490e8dbb80(0000) GS:ffff95d73bc00000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 00007f6e75555cb0 CR3: 00000001101ce001 CR4: 0000000000370ef0
  Call Trace:
   btrfs_commit_transaction+0x43c/0xb00
   ? finish_wait+0x80/0x80
   ? vfs_fsync_range+0x90/0x90
   iterate_supers+0x8c/0x100
   ksys_sync+0x50/0x90
   __do_sys_sync+0xa/0x10
   do_syscall_64+0x3d/0x80
   entry_SYSCALL_64_after_hwframe+0x44/0xae

Because the iref isn't dropped and this leaves an elevated node->count,
so any release just re-queues it onto the delayed inodes list.  Fix this
by going to the out label to handle the proper cleanup of the delayed
node.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

fs/btrfs/delayed-inode.c

@@ -1025,12 +1025,10 @@ static int __btrfs_update_delayed_inode(struct btrfs_trans_handle *trans,
 	nofs_flag = memalloc_nofs_save();
 	ret = btrfs_lookup_inode(trans, root, path, &key, mod);
 	memalloc_nofs_restore(nofs_flag);
-	if (ret > 0) {
-		btrfs_release_path(path);
-		return -ENOENT;
-	} else if (ret < 0) {
-		return ret;
-	}
+	if (ret > 0)
+		ret = -ENOENT;
+	if (ret < 0)
+		goto out;
 
 	leaf = path->nodes[0];
 	inode_item = btrfs_item_ptr(leaf, path->slots[0],