Full back reference support

This patch makes the back reference system to explicit record the
location of parent node for all types of extents. The location of
parent node is placed into the offset field of backref key. Every
time a tree block is balanced, the back references for the affected
lower level extents are updated.

1 files changed, 48 insertions, 22 deletions

diff --git a/convert.c b/convert.c
index 869df8d6..5a3c1413 100644
--- a/convert.c
+++ b/convert.c
@@ -317,6 +317,8 @@ static int record_file_extent(struct btrfs_trans_handle *trans,
 	int ret;
 	struct btrfs_fs_info *info = root->fs_info;
 	struct btrfs_root *extent_root = info->extent_root;
+	struct extent_buffer *leaf;
+	struct btrfs_file_extent_item *fi;
 	struct btrfs_key ins_key;
 	struct btrfs_path path;
 	struct btrfs_extent_item extent_item;
@@ -324,13 +326,15 @@ static int record_file_extent(struct btrfs_trans_handle *trans,
 	u64 nblocks;
 	u64 bytes_used;
 
-	ret = btrfs_insert_file_extent(trans, root, objectid, file_pos,
-				       disk_bytenr, num_bytes, num_bytes);
-	if (ret || disk_bytenr == 0)
+	if (disk_bytenr == 0) {
+		ret = btrfs_insert_file_extent(trans, root, objectid,
+						file_pos, disk_bytenr,
+						num_bytes, num_bytes);
 		return ret;
+	}
+
+	btrfs_init_path(&path);
 
-	nblocks = btrfs_stack_inode_nblocks(inode) + num_bytes / 512;
-	btrfs_set_stack_inode_nblocks(inode, nblocks);
 	if (checksum) {
 		u64 offset;
 		char *buffer;
@@ -355,36 +359,53 @@ static int record_file_extent(struct btrfs_trans_handle *trans,
 			goto fail;
 	}
 
+	ins_key.objectid = objectid;
+	ins_key.offset = file_pos;
+	btrfs_set_key_type(&ins_key, BTRFS_EXTENT_DATA_KEY);
+	ret = btrfs_insert_empty_item(trans, root, &path, &ins_key,
+				      sizeof(*fi));
+	if (ret)
+		goto fail;
+	leaf = path.nodes[0];
+	fi = btrfs_item_ptr(leaf, path.slots[0],
+			    struct btrfs_file_extent_item);
+	btrfs_set_file_extent_generation(leaf, fi, trans->transid);
+	btrfs_set_file_extent_type(leaf, fi, BTRFS_FILE_EXTENT_REG);
+	btrfs_set_file_extent_disk_bytenr(leaf, fi, disk_bytenr);
+	btrfs_set_file_extent_disk_num_bytes(leaf, fi, num_bytes);
+	btrfs_set_file_extent_offset(leaf, fi, 0);
+	btrfs_set_file_extent_num_bytes(leaf, fi, num_bytes);
+	btrfs_mark_buffer_dirty(leaf);
+
+	nblocks = btrfs_stack_inode_nblocks(inode) + num_bytes / 512;
+	btrfs_set_stack_inode_nblocks(inode, nblocks);
+
 	bytes_used = btrfs_root_used(&root->root_item);
 	btrfs_set_root_used(&root->root_item, bytes_used + num_bytes);
+
 	ins_key.objectid = disk_bytenr;
 	ins_key.offset = num_bytes;
 	btrfs_set_key_type(&ins_key, BTRFS_EXTENT_ITEM_KEY);
-	btrfs_set_stack_extent_refs(&extent_item, 1);
+	btrfs_set_stack_extent_refs(&extent_item, 0);
 	ret = btrfs_insert_item(trans, extent_root, &ins_key,
 				&extent_item, sizeof(extent_item));
 	if (ret == 0) {
 		bytes_used = btrfs_super_bytes_used(&info->super_copy);
 		btrfs_set_super_bytes_used(&info->super_copy, bytes_used +
 					   num_bytes);
-		btrfs_init_path(&path);
-		ret = btrfs_insert_extent_backref(trans, extent_root, &path,
-					disk_bytenr, root->root_key.objectid,
-					trans->transid, objectid, file_pos);
-		if (ret)
-			goto fail;
-		ret = btrfs_update_block_group(trans, root, disk_bytenr,
-					       num_bytes, 1, 0);
-	} else if (ret == -EEXIST) {
-		ret = btrfs_inc_extent_ref(trans, root, disk_bytenr, num_bytes,
-					   root->root_key.objectid,
-					   trans->transid, objectid, file_pos);
+	} else if (ret != -EEXIST) {
+		goto fail;
 	}
+	btrfs_extent_post_op(trans, extent_root);
+
+	ret = btrfs_inc_extent_ref(trans, root, disk_bytenr, num_bytes,
+				   leaf->start, root->root_key.objectid,
+				   trans->transid, objectid, file_pos);
 	if (ret)
 		goto fail;
-	btrfs_extent_post_op(trans, extent_root);
-	return 0;
+	ret = 0;
 fail:
+	btrfs_release_path(root, &path);
 	return ret;
 }
 
@@ -1795,6 +1816,13 @@ static int relocate_one_reference(struct btrfs_trans_handle *trans,
 	ret = btrfs_del_item(trans, root, &path);
 	if (ret)
 		goto fail;
+
+	ret = btrfs_free_extent(trans, root, extent_start, extent_size,
+				leaf->start, root_owner, root_gen, objectid,
+				offset, 0);
+	if (ret)
+		goto fail;
+
 	btrfs_release_path(root, &path);
 
 	key.objectid = objectid;
@@ -1887,8 +1915,6 @@ static int relocate_one_reference(struct btrfs_trans_handle *trans,
 	btrfs_mark_buffer_dirty(leaf);
 	btrfs_release_path(root, &path);
 
-	ret = btrfs_free_extent(trans, root, extent_start, extent_size,
-				root_owner, root_gen, objectid, offset, 0);
 fail:
 	btrfs_release_path(root, &path);
 	return ret;