Btrfs: Add backrefs and forward refs for subvols and snapshots

[linux-2.6-omap-h63xx.git] / fs / btrfs / root-tree.c

diff --git a/fs/btrfs/root-tree.c b/fs/btrfs/root-tree.c
index eb7f7655e9d5e1fdaa2665eb6ad7e0dd79ae6c60..e9be3abcb368391dce1a78ccb8ede44431a03baa 100644 (file)
--- a/fs/btrfs/root-tree.c
+++ b/fs/btrfs/root-tree.c
@@ -84,7 +84,7 @@ int btrfs_find_last_root(struct btrfs_root *root, u64 objectid,
        int slot;
 
        search_key.objectid = objectid;
-       search_key.type = (u8)-1;
+       search_key.type = BTRFS_ROOT_ITEM_KEY;
        search_key.offset = (u64)-1;
 
        path = btrfs_alloc_path();
@@ -275,3 +275,77 @@ out:
        btrfs_free_path(path);
        return ret;
 }
+
+int btrfs_del_root_ref(struct btrfs_trans_handle *trans,
+                      struct btrfs_root *tree_root,
+                      u64 root_id, u8 type, u64 ref_id)
+{
+       struct btrfs_key key;
+       int ret;
+       struct btrfs_path *path;
+
+       path = btrfs_alloc_path();
+
+       key.objectid = root_id;
+       key.type = type;
+       key.offset = ref_id;
+
+       ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);
+       BUG_ON(ret);
+
+       ret = btrfs_del_item(trans, tree_root, path);
+       BUG_ON(ret);
+
+       btrfs_free_path(path);
+       return ret;
+}
+
+/*
+ * add a btrfs_root_ref item.  type is either BTRFS_ROOT_REF_KEY
+ * or BTRFS_ROOT_BACKREF_KEY.
+ *
+ * The dirid, sequence, name and name_len refer to the directory entry
+ * that is referencing the root.
+ *
+ * For a forward ref, the root_id is the id of the tree referencing
+ * the root and ref_id is the id of the subvol  or snapshot.
+ *
+ * For a back ref the root_id is the id of the subvol or snapshot and
+ * ref_id is the id of the tree referencing it.
+ */
+int btrfs_add_root_ref(struct btrfs_trans_handle *trans,
+                      struct btrfs_root *tree_root,
+                      u64 root_id, u8 type, u64 ref_id,
+                      u64 dirid, u64 sequence,
+                      const char *name, int name_len)
+{
+       struct btrfs_key key;
+       int ret;
+       struct btrfs_path *path;
+       struct btrfs_root_ref *ref;
+       struct extent_buffer *leaf;
+       unsigned long ptr;
+
+
+       path = btrfs_alloc_path();
+
+       key.objectid = root_id;
+       key.type = type;
+       key.offset = ref_id;
+
+       ret = btrfs_insert_empty_item(trans, tree_root, path, &key,
+                                     sizeof(*ref) + name_len);
+       BUG_ON(ret);
+
+       leaf = path->nodes[0];
+       ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
+       btrfs_set_root_ref_dirid(leaf, ref, dirid);
+       btrfs_set_root_ref_sequence(leaf, ref, sequence);
+       btrfs_set_root_ref_name_len(leaf, ref, name_len);
+       ptr = (unsigned long)(ref + 1);
+       write_extent_buffer(leaf, name, ptr, name_len);
+       btrfs_mark_buffer_dirty(leaf);
+
+       btrfs_free_path(path);
+       return ret;
+}