Btrfs: use set_nlink if our i_nlink is 0

We need to inc the nlink of deleted entries when running replay so we can do the
unlink on the fs_root and get everything cleaned up and then have the orphan
cleanup do the right thing.  The problem is inc_nlink complains about this, even
thought it still does the right thing.  So use set_nlink() if our i_nlink is 0
to keep users from seeing the warnings during log replay.  Thanks,
Signed-off-by: NJosef Bacik <jbacik@fusionio.com>

fs/btrfs/tree-log.c

@@ -1382,7 +1382,10 @@ static noinline int link_to_fixup_dir(struct btrfs_trans_handle *trans,
 
 	btrfs_release_path(path);
 	if (ret == 0) {
-		btrfs_inc_nlink(inode);
+		if (!inode->i_nlink)
+			set_nlink(inode, 1);
+		else
+			btrfs_inc_nlink(inode);
 		ret = btrfs_update_inode(trans, root, inode);
 	} else if (ret == -EEXIST) {
 		ret = 0;