Btrfs: Change the super to point to a tree of trees to enable persistent snapshots
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Chris Mason
committed by
David Woodhouse
David Woodhouse
parent
eaee50e881
commit
3768f3689f
@@ -154,41 +154,96 @@ static int __commit_transaction(struct btrfs_root *root)
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return ret;
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}
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static int commit_extent_and_tree_roots(struct btrfs_root *tree_root,
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struct btrfs_root *extent_root)
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{
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int ret;
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u64 old_extent_block;
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while(1) {
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old_extent_block = btrfs_root_blocknr(&extent_root->root_item);
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if (old_extent_block == extent_root->node->blocknr)
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break;
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btrfs_set_root_blocknr(&extent_root->root_item,
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extent_root->node->blocknr);
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ret = btrfs_update_root(tree_root,
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&extent_root->root_key,
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&extent_root->root_item);
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BUG_ON(ret);
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}
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__commit_transaction(extent_root);
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__commit_transaction(tree_root);
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return 0;
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}
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int btrfs_commit_transaction(struct btrfs_root *root,
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struct btrfs_super_block *s)
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{
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int ret = 0;
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struct btrfs_buffer *snap = root->commit_root;
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struct btrfs_key snap_key;
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ret = __commit_transaction(root);
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if (!ret && root != root->extent_root)
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ret = __commit_transaction(root->extent_root);
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BUG_ON(ret);
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if (root->commit_root != root->node) {
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struct btrfs_buffer *snap = root->commit_root;
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root->commit_root = root->node;
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root->node->count++;
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ret = btrfs_drop_snapshot(root, snap);
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BUG_ON(ret);
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// btrfs_block_release(root, snap);
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}
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if (root->commit_root == root->node)
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return 0;
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memcpy(&snap_key, &root->root_key, sizeof(snap_key));
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root->root_key.offset++;
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btrfs_set_root_blocknr(&root->root_item, root->node->blocknr);
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ret = btrfs_insert_root(root->tree_root, &root->root_key,
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&root->root_item);
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BUG_ON(ret);
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ret = commit_extent_and_tree_roots(root->tree_root, root->extent_root);
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BUG_ON(ret);
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write_ctree_super(root, s);
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btrfs_finish_extent_commit(root);
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btrfs_finish_extent_commit(root->extent_root);
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btrfs_finish_extent_commit(root->tree_root);
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root->commit_root = root->node;
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root->node->count++;
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ret = btrfs_drop_snapshot(root, snap);
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BUG_ON(ret);
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ret = btrfs_del_root(root->tree_root, &snap_key);
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BUG_ON(ret);
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return ret;
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}
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static int __setup_root(struct btrfs_root *root, struct btrfs_root *extent_root,
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struct btrfs_root_info *info, int fp)
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static int __setup_root(struct btrfs_root *root, u64 objectid, int fp)
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{
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INIT_LIST_HEAD(&root->trans);
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INIT_LIST_HEAD(&root->cache);
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root->cache_size = 0;
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root->fp = fp;
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root->node = NULL;
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root->extent_root = extent_root;
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root->commit_root = NULL;
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root->node = read_tree_block(root, info->tree_root);
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memset(&root->current_insert, 0, sizeof(root->current_insert));
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memset(&root->last_insert, 0, sizeof(root->last_insert));
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memset(&root->root_key, 0, sizeof(root->root_key));
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memset(&root->root_item, 0, sizeof(root->root_item));
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return 0;
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}
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static int find_and_setup_root(struct btrfs_root *tree_root, u64 objectid,
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struct btrfs_root *root, int fp)
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{
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int ret;
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__setup_root(root, objectid, fp);
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ret = btrfs_find_last_root(tree_root, objectid,
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&root->root_item, &root->root_key);
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BUG_ON(ret);
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root->node = read_tree_block(root,
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btrfs_root_blocknr(&root->root_item));
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root->ref_cows = 0;
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BUG_ON(!root->node);
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return 0;
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}
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@@ -196,9 +251,19 @@ struct btrfs_root *open_ctree(char *filename, struct btrfs_super_block *super)
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{
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struct btrfs_root *root = malloc(sizeof(struct btrfs_root));
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struct btrfs_root *extent_root = malloc(sizeof(struct btrfs_root));
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struct btrfs_root *tree_root = malloc(sizeof(struct btrfs_root));
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int fp;
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int ret;
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root->extent_root = extent_root;
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root->tree_root = tree_root;
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extent_root->extent_root = extent_root;
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extent_root->tree_root = tree_root;
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tree_root->extent_root = extent_root;
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tree_root->tree_root = tree_root;
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fp = open(filename, O_CREAT | O_RDWR, 0600);
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if (fp < 0) {
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free(root);
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@@ -208,11 +273,14 @@ struct btrfs_root *open_ctree(char *filename, struct btrfs_super_block *super)
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INIT_RADIX_TREE(&root->pinned_radix, GFP_KERNEL);
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INIT_RADIX_TREE(&extent_root->pinned_radix, GFP_KERNEL);
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INIT_RADIX_TREE(&extent_root->cache_radix, GFP_KERNEL);
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INIT_RADIX_TREE(&tree_root->pinned_radix, GFP_KERNEL);
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INIT_RADIX_TREE(&tree_root->cache_radix, GFP_KERNEL);
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ret = pread(fp, super, sizeof(struct btrfs_super_block),
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BTRFS_SUPER_INFO_OFFSET(BTRFS_BLOCKSIZE));
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if (ret == 0 || super->root_info.tree_root == 0) {
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if (ret == 0 || btrfs_super_root(super) == 0) {
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printf("making new FS!\n");
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ret = mkfs(fp);
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ret = mkfs(fp, 0, BTRFS_BLOCKSIZE);
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if (ret)
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return NULL;
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ret = pread(fp, super, sizeof(struct btrfs_super_block),
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@@ -221,24 +289,29 @@ struct btrfs_root *open_ctree(char *filename, struct btrfs_super_block *super)
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return NULL;
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}
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BUG_ON(ret < 0);
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__setup_root(root, extent_root, &super->root_info, fp);
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__setup_root(extent_root, extent_root, &super->extent_info, fp);
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__setup_root(tree_root, BTRFS_ROOT_TREE_OBJECTID, fp);
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tree_root->node = read_tree_block(tree_root, btrfs_super_root(super));
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BUG_ON(!tree_root->node);
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ret = find_and_setup_root(tree_root, BTRFS_EXTENT_TREE_OBJECTID,
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extent_root, fp);
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BUG_ON(ret);
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ret = find_and_setup_root(tree_root, BTRFS_FS_TREE_OBJECTID,
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root, fp);
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BUG_ON(ret);
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root->commit_root = root->node;
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root->node->count++;
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root->ref_cows = 1;
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return root;
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}
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static int __update_root(struct btrfs_root *root, struct btrfs_root_info *info)
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{
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info->tree_root = root->node->blocknr;
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return 0;
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}
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int write_ctree_super(struct btrfs_root *root, struct btrfs_super_block *s)
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{
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int ret;
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__update_root(root, &s->root_info);
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__update_root(root->extent_root, &s->extent_info);
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btrfs_set_super_root(s, root->tree_root->node->blocknr);
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ret = pwrite(root->fp, s, sizeof(*s),
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BTRFS_SUPER_INFO_OFFSET(BTRFS_BLOCKSIZE));
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if (ret != sizeof(*s)) {
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@@ -260,19 +333,25 @@ static int drop_cache(struct btrfs_root *root)
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}
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int close_ctree(struct btrfs_root *root, struct btrfs_super_block *s)
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{
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int ret;
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btrfs_commit_transaction(root, s);
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__commit_transaction(root->extent_root);
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ret = commit_extent_and_tree_roots(root->tree_root, root->extent_root);
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BUG_ON(ret);
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write_ctree_super(root, s);
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drop_cache(root->extent_root);
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drop_cache(root->tree_root);
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drop_cache(root);
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BUG_ON(!list_empty(&root->trans));
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BUG_ON(!list_empty(&root->extent_root->trans));
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BUG_ON(!list_empty(&root->tree_root->trans));
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close(root->fp);
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if (root->node)
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btrfs_block_release(root, root->node);
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if (root->extent_root->node)
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btrfs_block_release(root->extent_root, root->extent_root->node);
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if (root->tree_root->node)
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btrfs_block_release(root->tree_root, root->tree_root->node);
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btrfs_block_release(root, root->commit_root);
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free(root);
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printf("on close %d blocks are allocated\n", allocated_blocks);
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