Btrfs: Add back pointers from the inode to the directory that references it
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/inode-item.c b/fs/btrfs/inode-item.c
index 35d2608..cba30b6 100644
--- a/fs/btrfs/inode-item.c
+++ b/fs/btrfs/inode-item.c
@@ -20,6 +20,142 @@
#include "disk-io.h"
#include "transaction.h"
+int find_name_in_backref(struct btrfs_path *path, const char * name,
+ int name_len, struct btrfs_inode_ref **ref_ret)
+{
+ struct extent_buffer *leaf;
+ struct btrfs_inode_ref *ref;
+ unsigned long ptr;
+ unsigned long name_ptr;
+ u32 item_size;
+ u32 cur_offset = 0;
+ int len;
+
+ leaf = path->nodes[0];
+ item_size = btrfs_item_size_nr(leaf, path->slots[0]);
+ ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
+ while (cur_offset < item_size) {
+ ref = (struct btrfs_inode_ref *)(ptr + cur_offset);
+ len = btrfs_inode_ref_name_len(leaf, ref);
+ name_ptr = (unsigned long)(ref + 1);
+ cur_offset += len + sizeof(*ref);
+ if (len != name_len)
+ continue;
+ if (memcmp_extent_buffer(leaf, name, name_ptr, name_len) == 0) {
+ *ref_ret = ref;
+ return 1;
+ }
+ }
+ return 0;
+}
+
+int btrfs_del_inode_ref(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root,
+ const char *name, int name_len,
+ u64 inode_objectid, u64 ref_objectid)
+{
+ struct btrfs_path *path;
+ struct btrfs_key key;
+ struct btrfs_inode_ref *ref;
+ struct extent_buffer *leaf;
+ unsigned long ptr;
+ unsigned long item_start;
+ u32 item_size;
+ u32 sub_item_len;
+ int ret;
+ int del_len = name_len + sizeof(*ref);
+
+ key.objectid = inode_objectid;
+ key.offset = ref_objectid;
+ btrfs_set_key_type(&key, BTRFS_INODE_REF_KEY);
+
+ path = btrfs_alloc_path();
+ if (!path)
+ return -ENOMEM;
+
+ ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
+ if (ret > 0) {
+ ret = -ENOENT;
+ goto out;
+ } else if (ret < 0) {
+ goto out;
+ }
+ if (!find_name_in_backref(path, name, name_len, &ref)) {
+ ret = -ENOENT;
+ goto out;
+ }
+ leaf = path->nodes[0];
+ item_size = btrfs_item_size_nr(leaf, path->slots[0]);
+ if (del_len == item_size) {
+ ret = btrfs_del_item(trans, root, path);
+ goto out;
+ }
+ ptr = (unsigned long)ref;
+ sub_item_len = name_len + sizeof(*ref);
+ item_start = btrfs_item_ptr_offset(leaf, path->slots[0]);
+ memmove_extent_buffer(leaf, ptr, ptr + sub_item_len,
+ item_size - (ptr + sub_item_len - item_start));
+ ret = btrfs_truncate_item(trans, root, path,
+ item_size - sub_item_len, 1);
+ BUG_ON(ret);
+out:
+ btrfs_free_path(path);
+ return ret;
+}
+
+int btrfs_insert_inode_ref(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root,
+ const char *name, int name_len,
+ u64 inode_objectid, u64 ref_objectid)
+{
+ struct btrfs_path *path;
+ struct btrfs_key key;
+ struct btrfs_inode_ref *ref;
+ unsigned long ptr;
+ int ret;
+ int ins_len = name_len + sizeof(*ref);
+
+ key.objectid = inode_objectid;
+ key.offset = ref_objectid;
+ btrfs_set_key_type(&key, BTRFS_INODE_REF_KEY);
+
+ path = btrfs_alloc_path();
+ if (!path)
+ return -ENOMEM;
+
+ ret = btrfs_insert_empty_item(trans, root, path, &key,
+ ins_len);
+ if (ret == -EEXIST) {
+ u32 old_size;
+
+ if (find_name_in_backref(path, name, name_len, &ref))
+ goto out;
+
+ old_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]);
+ ret = btrfs_extend_item(trans, root, path, ins_len);
+ BUG_ON(ret);
+ ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
+ struct btrfs_inode_ref);
+ ref = (struct btrfs_inode_ref *)((unsigned long)ref + old_size);
+ btrfs_set_inode_ref_name_len(path->nodes[0], ref, name_len);
+ ptr = (unsigned long)(ref + 1);
+ ret = 0;
+ } else if (ret < 0) {
+ goto out;
+ } else {
+ ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
+ struct btrfs_inode_ref);
+ btrfs_set_inode_ref_name_len(path->nodes[0], ref, name_len);
+ ptr = (unsigned long)(ref + 1);
+ }
+ write_extent_buffer(path->nodes[0], name, ptr, name_len);
+ btrfs_mark_buffer_dirty(path->nodes[0]);
+
+out:
+ btrfs_free_path(path);
+ return ret;
+}
+
int btrfs_insert_empty_inode(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct btrfs_path *path, u64 objectid)