lk/linux-kernel-test
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Btrfs: change how subvolumes are organized

Browse Source 
btrfs allows subvolumes and snapshots anywhere in the directory tree.
If we snapshot a subvolume that contains a link to other subvolume
called subvolA, subvolA can be accessed through both the original
subvolume and the snapshot. This is similar to creating hard link to
directory, and has the very similar problems.

The aim of this patch is enforcing there is only one access point to
each subvolume. Only the first directory entry (the one added when
the subvolume/snapshot was created) is treated as valid access point.
The first directory entry is distinguished by checking root forward
reference. If the corresponding root forward reference is missing,
we know the entry is not the first one.

This patch also adds snapshot/subvolume rename support, the code
allows rename subvolume link across subvolumes.

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Yan, Zheng
2009-09-21 15:56:00 -04:00
committed by Chris Mason
parent 13a8a7c8c4
commit 4df27c4d5c
9 changed files with 459 additions and 168 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
fs/btrfs/transaction.c
View File

@@ -779,24 +779,14 @@ static noinline int finish_pending_snapshot(struct btrfs_fs_info *fs_info,
ret = btrfs_update_inode(trans, parent_root, parent_inode);
BUG_ON(ret);
/* 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: