Btrfs: Change the super to point to a tree of trees to enable persistent snapshots
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index c34c0c6..3d4bf68 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -154,41 +154,96 @@
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 *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 @@
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 @@
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 @@
}
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);
