Change the super to point to a tree of trees to enable persistent snapshots

1 files changed, 107 insertions, 28 deletions

diff --git a/disk-io.c b/disk-io.c
index c34c0c60..3d4bf683 100644
--- a/disk-io.c
+++ b/disk-io.c
@@ -154,41 +154,96 @@ static int __commit_transaction(struct btrfs_root *root)
 	return ret;
 }
 
+static int commit_extent_and_tree_roots(struct btrfs_root *tree_root,
+					struct btrfs_root *extent_root)
+{
+	int ret;
+	u64 old_extent_block;
+
+	while(1) {
+		old_extent_block = btrfs_root_blocknr(&extent_root->root_item);
+		if (old_extent_block == extent_root->node->blocknr)
+			break;
+		btrfs_set_root_blocknr(&extent_root->root_item,
+				       extent_root->node->blocknr);
+		ret = btrfs_update_root(tree_root,
+					&extent_root->root_key,
+					&extent_root->root_item);
+		BUG_ON(ret);
+	}
+	__commit_transaction(extent_root);
+	__commit_transaction(tree_root);
+	return 0;
+}
+
 int btrfs_commit_transaction(struct btrfs_root *root,
 			     struct btrfs_super_block *s)
 {
 	int ret = 0;
+	struct btrfs_buffer *snap = root->commit_root;
+	struct btrfs_key snap_key;
 
 	ret = __commit_transaction(root);
-	if (!ret && root != root->extent_root)
-		ret = __commit_transaction(root->extent_root);
 	BUG_ON(ret);
-	if (root->commit_root != root->node) {
-		struct btrfs_buffer *snap = root->commit_root;
-		root->commit_root = root->node;
-		root->node->count++;
-		ret = btrfs_drop_snapshot(root, snap);
-		BUG_ON(ret);
-		// btrfs_block_release(root, snap);
-	}
+
+	if (root->commit_root == root->node)
+		return 0;
+
+	memcpy(&snap_key, &root->root_key, sizeof(snap_key));
+	root->root_key.offset++;
+
+	btrfs_set_root_blocknr(&root->root_item, root->node->blocknr);
+	ret = btrfs_insert_root(root->tree_root, &root->root_key,
+				&root->root_item);
+	BUG_ON(ret);
+
+	ret = commit_extent_and_tree_roots(root->tree_root, root->extent_root);
+	BUG_ON(ret);
+
         write_ctree_super(root, s);
-	btrfs_finish_extent_commit(root);
+	btrfs_finish_extent_commit(root->extent_root);
+	btrfs_finish_extent_commit(root->tree_root);
+
+	root->commit_root = root->node;
+	root->node->count++;
+	ret = btrfs_drop_snapshot(root, snap);
+	BUG_ON(ret);
+
+	ret = btrfs_del_root(root->tree_root, &snap_key);
+	BUG_ON(ret);
+
 	return ret;
 }
 
-static int __setup_root(struct btrfs_root *root, struct btrfs_root *extent_root,
-			struct btrfs_root_info *info, int fp)
+static int __setup_root(struct btrfs_root *root, u64 objectid, int fp)
 {
 	INIT_LIST_HEAD(&root->trans);
 	INIT_LIST_HEAD(&root->cache);
 	root->cache_size = 0;
 	root->fp = fp;
 	root->node = NULL;
-	root->extent_root = extent_root;
 	root->commit_root = NULL;
-	root->node = read_tree_block(root, info->tree_root);
 	memset(&root->current_insert, 0, sizeof(root->current_insert));
 	memset(&root->last_insert, 0, sizeof(root->last_insert));
+	memset(&root->root_key, 0, sizeof(root->root_key));
+	memset(&root->root_item, 0, sizeof(root->root_item));
+	return 0;
+}
+
+static int find_and_setup_root(struct btrfs_root *tree_root, u64 objectid,
+			struct btrfs_root *root, int fp)
+{
+	int ret;
+
+	__setup_root(root, objectid, fp);
+	ret = btrfs_find_last_root(tree_root, objectid,
+				   &root->root_item, &root->root_key);
+	BUG_ON(ret);
+
+	root->node = read_tree_block(root,
+				     btrfs_root_blocknr(&root->root_item));
+	root->ref_cows = 0;
+	BUG_ON(!root->node);
 	return 0;
 }
 
@@ -196,9 +251,19 @@ struct btrfs_root *open_ctree(char *filename, struct btrfs_super_block *super)
 {
 	struct btrfs_root *root = malloc(sizeof(struct btrfs_root));
 	struct btrfs_root *extent_root = malloc(sizeof(struct btrfs_root));
+	struct btrfs_root *tree_root = malloc(sizeof(struct btrfs_root));
 	int fp;
 	int ret;
 
+	root->extent_root = extent_root;
+	root->tree_root = tree_root;
+
+	extent_root->extent_root = extent_root;
+	extent_root->tree_root = tree_root;
+
+	tree_root->extent_root = extent_root;
+	tree_root->tree_root = tree_root;
+
 	fp = open(filename, O_CREAT | O_RDWR, 0600);
 	if (fp < 0) {
 		free(root);
@@ -208,11 +273,14 @@ struct btrfs_root *open_ctree(char *filename, struct btrfs_super_block *super)
 	INIT_RADIX_TREE(&root->pinned_radix, GFP_KERNEL);
 	INIT_RADIX_TREE(&extent_root->pinned_radix, GFP_KERNEL);
 	INIT_RADIX_TREE(&extent_root->cache_radix, GFP_KERNEL);
+	INIT_RADIX_TREE(&tree_root->pinned_radix, GFP_KERNEL);
+	INIT_RADIX_TREE(&tree_root->cache_radix, GFP_KERNEL);
+
 	ret = pread(fp, super, sizeof(struct btrfs_super_block),
 		     BTRFS_SUPER_INFO_OFFSET(BTRFS_BLOCKSIZE));
-	if (ret == 0 || super->root_info.tree_root == 0) {
+	if (ret == 0 || btrfs_super_root(super) == 0) {
 		printf("making new FS!\n");
-		ret = mkfs(fp);
+		ret = mkfs(fp, 0, BTRFS_BLOCKSIZE);
 		if (ret)
 			return NULL;
 		ret = pread(fp, super, sizeof(struct btrfs_super_block),
@@ -221,24 +289,29 @@ struct btrfs_root *open_ctree(char *filename, struct btrfs_super_block *super)
 			return NULL;
 	}
 	BUG_ON(ret < 0);
-	__setup_root(root, extent_root, &super->root_info, fp);
-	__setup_root(extent_root, extent_root, &super->extent_info, fp);
+
+	__setup_root(tree_root, BTRFS_ROOT_TREE_OBJECTID, fp);
+	tree_root->node = read_tree_block(tree_root, btrfs_super_root(super));
+	BUG_ON(!tree_root->node);
+
+	ret = find_and_setup_root(tree_root, BTRFS_EXTENT_TREE_OBJECTID,
+				  extent_root, fp);
+	BUG_ON(ret);
+
+	ret = find_and_setup_root(tree_root, BTRFS_FS_TREE_OBJECTID,
+				  root, fp);
+	BUG_ON(ret);
+
 	root->commit_root = root->node;
 	root->node->count++;
+	root->ref_cows = 1;
 	return root;
 }
 
-static int __update_root(struct btrfs_root *root, struct btrfs_root_info *info)
-{
-	info->tree_root = root->node->blocknr;
-	return 0;
-}
-
 int write_ctree_super(struct btrfs_root *root, struct btrfs_super_block *s)
 {
 	int ret;
-	__update_root(root, &s->root_info);
-	__update_root(root->extent_root, &s->extent_info);
+	btrfs_set_super_root(s, root->tree_root->node->blocknr);
 	ret = pwrite(root->fp, s, sizeof(*s),
 		     BTRFS_SUPER_INFO_OFFSET(BTRFS_BLOCKSIZE));
 	if (ret != sizeof(*s)) {
@@ -260,19 +333,25 @@ static int drop_cache(struct btrfs_root *root)
 }
 int close_ctree(struct btrfs_root *root, struct btrfs_super_block *s)
 {
+	int ret;
 	btrfs_commit_transaction(root, s);
-	__commit_transaction(root->extent_root);
+	ret = commit_extent_and_tree_roots(root->tree_root, root->extent_root);
+	BUG_ON(ret);
 	write_ctree_super(root, s);
 	drop_cache(root->extent_root);
+	drop_cache(root->tree_root);
 	drop_cache(root);
 	BUG_ON(!list_empty(&root->trans));
 	BUG_ON(!list_empty(&root->extent_root->trans));
+	BUG_ON(!list_empty(&root->tree_root->trans));
 
 	close(root->fp);
 	if (root->node)
 		btrfs_block_release(root, root->node);
 	if (root->extent_root->node)
 		btrfs_block_release(root->extent_root, root->extent_root->node);
+	if (root->tree_root->node)
+		btrfs_block_release(root->tree_root, root->tree_root->node);
 	btrfs_block_release(root, root->commit_root);
 	free(root);
 	printf("on close %d blocks are allocated\n", allocated_blocks);