/*
* this is used to update the root pointer in the tree of tree roots.
*
* But, in the case of the extent allocation tree, updating the root
* pointer may allocate blocks which may change the root of the extent
* allocation tree.
*
* So, this loops and repeats and makes sure the cowonly root didn't
* change while the root pointer was being updated in the metadata.
*/
static int update_cowonly_root(struct btrfs_trans_handle *trans,
struct btrfs_root *root)
{
int ret;
u64 old_root_bytenr;
struct btrfs_root *tree_root = root->fs_info->tree_root;
btrfs_write_dirty_block_groups(trans, root);
while (1) {
old_root_bytenr = btrfs_root_bytenr(&root->root_item);
if (old_root_bytenr == root->node->start)
break;
btrfs_set_root_node(&root->root_item, root->node);
ret = btrfs_update_root(trans, tree_root,
&root->root_key,
&root->root_item);
BUG_ON(ret);
ret = btrfs_write_dirty_block_groups(trans, root);
BUG_ON(ret);
}
if (root != root->fs_info->extent_root)
switch_commit_root(root);
return 0;
}
/*
* new snapshots need to be created at a very specific time in the
* transaction commit. This does the actual creation
*/
static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
struct btrfs_fs_info *fs_info,
struct btrfs_pending_snapshot *pending)
{
struct btrfs_key key;
struct btrfs_root_item *new_root_item;
struct btrfs_root *tree_root = fs_info->tree_root;
struct btrfs_root *root = pending->root;
struct extent_buffer *tmp;
struct extent_buffer *old;
int ret;
u64 objectid;
new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
if (!new_root_item) {
ret = -ENOMEM;
goto fail;
}
ret = btrfs_find_free_objectid(trans, tree_root, 0, &objectid);
if (ret)
goto fail;
record_root_in_trans(trans, root);
btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
key.objectid = objectid;
/* record when the snapshot was created in key.offset */
key.offset = trans->transid;
btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
old = btrfs_lock_root_node(root);
btrfs_cow_block(trans, root, old, NULL, 0, &old);
btrfs_set_lock_blocking(old);
btrfs_copy_root(trans, root, old, &tmp, objectid);
btrfs_tree_unlock(old);
free_extent_buffer(old);
btrfs_set_root_node(new_root_item, tmp);
ret = btrfs_insert_root(trans, root->fs_info->tree_root, &key,
new_root_item);
btrfs_tree_unlock(tmp);
free_extent_buffer(tmp);
if (ret)
goto fail;
key.offset = (u64)-1;
memcpy(&pending->root_key, &key, sizeof(key));
fail:
kfree(new_root_item);
btrfs_unreserve_metadata_space(root, 6);
return ret;
}
static noinline int commit_fs_roots(struct btrfs_trans_handle *trans,
struct btrfs_root *root)
{
struct btrfs_root *gang[8];
struct btrfs_fs_info *fs_info = root->fs_info;
int i;
int ret;
int err = 0;
while (1) {
ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
(void **)gang, 0,
ARRAY_SIZE(gang),
BTRFS_ROOT_TRANS_TAG);
if (ret == 0)
break;
for (i = 0; i < ret; i++) {
root = gang[i];
radix_tree_tag_clear(&fs_info->fs_roots_radix,
(unsigned long)root->root_key.objectid,
BTRFS_ROOT_TRANS_TAG);
btrfs_free_log(trans, root);
btrfs_update_reloc_root(trans, root);
btrfs_orphan_commit_root(trans, root);
if (root->commit_root != root->node) {
switch_commit_root(root);
btrfs_set_root_node(&root->root_item,
root->node);
}
err = btrfs_update_root(trans, fs_info->tree_root,
&root->root_key,
&root->root_item);
if (err)
break;
}
}
return err;
}
static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
struct btrfs_fs_info *fs_info,
struct btrfs_pending_snapshot *pending)
{
struct btrfs_key key;
struct btrfs_root_item *new_root_item;
struct btrfs_root *tree_root = fs_info->tree_root;
struct btrfs_root *root = pending->root;
struct btrfs_root *parent_root;
struct inode *parent_inode;
struct dentry *dentry;
struct extent_buffer *tmp;
struct extent_buffer *old;
int ret;
int retries = 0;
u64 to_reserve = 0;
u64 index = 0;
u64 objectid;
new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
if (!new_root_item) {
pending->error = -ENOMEM;
goto fail;
}
ret = btrfs_find_free_objectid(trans, tree_root, 0, &objectid);
if (ret) {
pending->error = ret;
goto fail;
}
btrfs_reloc_pre_snapshot(trans, pending, &to_reserve);
btrfs_orphan_pre_snapshot(trans, pending, &to_reserve);
if (to_reserve > 0) {
ret = btrfs_block_rsv_add(trans, root, &pending->block_rsv,
to_reserve, &retries);
if (ret) {
pending->error = ret;
goto fail;
}
}
key.objectid = objectid;
key.offset = (u64)-1;
key.type = BTRFS_ROOT_ITEM_KEY;
trans->block_rsv = &pending->block_rsv;
dentry = pending->dentry;
parent_inode = dentry->d_parent->d_inode;
parent_root = BTRFS_I(parent_inode)->root;
record_root_in_trans(trans, parent_root);
/*
* insert the directory item
*/
ret = btrfs_set_inode_index(parent_inode, &index);
BUG_ON(ret);
ret = btrfs_insert_dir_item(trans, parent_root,
dentry->d_name.name, dentry->d_name.len,
parent_inode->i_ino, &key,
BTRFS_FT_DIR, index);
BUG_ON(ret);
btrfs_i_size_write(parent_inode, parent_inode->i_size +
dentry->d_name.len * 2);
ret = btrfs_update_inode(trans, parent_root, parent_inode);
BUG_ON(ret);
record_root_in_trans(trans, root);
btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
old = btrfs_lock_root_node(root);
btrfs_cow_block(trans, root, old, NULL, 0, &old);
btrfs_set_lock_blocking(old);
btrfs_copy_root(trans, root, old, &tmp, objectid);
btrfs_tree_unlock(old);
free_extent_buffer(old);
btrfs_set_root_node(new_root_item, tmp);
/* record when the snapshot was created in key.offset */
key.offset = trans->transid;
ret = btrfs_insert_root(trans, tree_root, &key, new_root_item);
btrfs_tree_unlock(tmp);
free_extent_buffer(tmp);
BUG_ON(ret);
/*
* insert root back/forward references
*/
ret = btrfs_add_root_ref(trans, tree_root, objectid,
parent_root->root_key.objectid,
parent_inode->i_ino, index,
dentry->d_name.name, dentry->d_name.len);
BUG_ON(ret);
key.offset = (u64)-1;
pending->snap = btrfs_read_fs_root_no_name(root->fs_info, &key);
BUG_ON(IS_ERR(pending->snap));
btrfs_reloc_post_snapshot(trans, pending);
btrfs_orphan_post_snapshot(trans, pending);
fail:
kfree(new_root_item);
btrfs_block_rsv_release(root, &pending->block_rsv, (u64)-1);
return 0;
}
