From 0660b5af3f7ac0fac69de975914e1f4a3a586fb3 Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Mon, 17 Nov 2008 20:37:39 -0500 Subject: Btrfs: Add backrefs and forward refs for subvols and snapshots Subvols and snapshots can now be referenced from any point in the directory tree. We need to maintain back refs for them so we can find lost subvols. Forward refs are added so that we know all of the subvols and snapshots referenced anywhere in the directory tree of a single subvol. This can be used to do recursive snapshotting (but they aren't yet) and it is also used to detect and prevent directory loops when creating new snapshots. Signed-off-by: Chris Mason --- fs/btrfs/transaction.c | 31 +++++++++++++++++++++++-------- 1 file changed, 23 insertions(+), 8 deletions(-) (limited to 'fs/btrfs/transaction.c') diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index 93f23a456a3..e9c8ebeedd7 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -831,28 +831,43 @@ static noinline int finish_pending_snapshot(struct btrfs_fs_info *fs_info, struct btrfs_trans_handle *trans; struct inode *parent_inode; struct inode *inode; + struct btrfs_root *parent_root; parent_inode = pending->dentry->d_parent->d_inode; - trans = btrfs_start_transaction(BTRFS_I(parent_inode)->root, 1); + parent_root = BTRFS_I(parent_inode)->root; + trans = btrfs_start_transaction(parent_root, 1); /* * insert the directory item */ namelen = strlen(pending->name); ret = btrfs_set_inode_index(parent_inode, &index); - ret = btrfs_insert_dir_item(trans, - BTRFS_I(parent_inode)->root, + ret = btrfs_insert_dir_item(trans, parent_root, pending->name, namelen, parent_inode->i_ino, &pending->root_key, BTRFS_FT_DIR, index); if (ret) goto fail; -#if 0 - ret = btrfs_insert_inode_ref(trans, root->fs_info->tree_root, - pending->name, strlen(pending->name), objectid, - root->fs_info->sb->s_root->d_inode->i_ino, 0); -#endif + + /* add the backref first */ + ret = btrfs_add_root_ref(trans, parent_root->fs_info->tree_root, + pending->root_key.objectid, + BTRFS_ROOT_BACKREF_KEY, + parent_root->root_key.objectid, + parent_inode->i_ino, index, pending->name, + namelen); + + BUG_ON(ret); + + /* now add the forward ref */ + ret = btrfs_add_root_ref(trans, parent_root->fs_info->tree_root, + parent_root->root_key.objectid, + BTRFS_ROOT_REF_KEY, + pending->root_key.objectid, + parent_inode->i_ino, index, pending->name, + namelen); + inode = btrfs_lookup_dentry(parent_inode, pending->dentry); d_instantiate(pending->dentry, inode); fail: -- cgit v1.2.3