switch btrfs, close races

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/btrfs/export.c

@@ -65,7 +65,6 @@ static struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid,
 {
 	struct btrfs_fs_info *fs_info = btrfs_sb(sb)->fs_info;
 	struct btrfs_root *root;
-	struct dentry *dentry;
 	struct inode *inode;
 	struct btrfs_key key;
 	int index;
@@ -108,10 +107,7 @@ static struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid,
 		return ERR_PTR(-ESTALE);
 	}
 
-	dentry = d_obtain_alias(inode);
-	if (!IS_ERR(dentry))
-		d_set_d_op(dentry, &btrfs_dentry_operations);
-	return dentry;
+	return d_obtain_alias(inode);
 fail:
 	srcu_read_unlock(&fs_info->subvol_srcu, index);
 	return ERR_PTR(err);
@@ -166,7 +162,6 @@ static struct dentry *btrfs_fh_to_dentry(struct super_block *sb, struct fid *fh,
 static struct dentry *btrfs_get_parent(struct dentry *child)
 {
 	struct inode *dir = child->d_inode;
-	struct dentry *dentry;
 	struct btrfs_root *root = BTRFS_I(dir)->root;
 	struct btrfs_path *path;
 	struct extent_buffer *leaf;
@@ -223,10 +218,7 @@ static struct dentry *btrfs_get_parent(struct dentry *child)
 
 	key.type = BTRFS_INODE_ITEM_KEY;
 	key.offset = 0;
-	dentry = d_obtain_alias(btrfs_iget(root->fs_info->sb, &key, root, NULL));
-	if (!IS_ERR(dentry))
-		d_set_d_op(dentry, &btrfs_dentry_operations);
-	return dentry;
+	return d_obtain_alias(btrfs_iget(root->fs_info->sb, &key, root, NULL));
 fail:
 	btrfs_free_path(path);
 	return ERR_PTR(ret);

fs/btrfs/inode.c

@@ -4084,8 +4084,6 @@ struct inode *btrfs_lookup_dentry(struct inode *dir, struct dentry *dentry)
 	int index;
 	int ret;
 
-	d_set_d_op(dentry, &btrfs_dentry_operations);
-
 	if (dentry->d_name.len > BTRFS_NAME_LEN)
 		return ERR_PTR(-ENAMETOOLONG);
 

fs/btrfs/super.c

@@ -460,6 +460,7 @@ static int btrfs_fill_super(struct super_block *sb,
 	sb->s_maxbytes = MAX_LFS_FILESIZE;
 	sb->s_magic = BTRFS_SUPER_MAGIC;
 	sb->s_op = &btrfs_super_ops;
+	sb->s_d_op = &btrfs_dentry_operations;
 	sb->s_export_op = &btrfs_export_ops;
 	sb->s_xattr = btrfs_xattr_handlers;
 	sb->s_time_gran = 1;