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author | Chris Mason <chris.mason@oracle.com> | 2008-11-18 02:14:24 (GMT) |
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committer | Chris Mason <chris.mason@oracle.com> | 2008-11-18 02:14:24 (GMT) |
commit | ea9e8b11bd1252dcbc23afefcf1a52ec6aa3c113 (patch) | |
tree | 3573c8d79e1936e8c921a3be77abda35124e0d78 /fs/btrfs/ioctl.c | |
parent | 0660b5af3f7ac0fac69de975914e1f4a3a586fb3 (diff) | |
download | linux-fsl-qoriq-ea9e8b11bd1252dcbc23afefcf1a52ec6aa3c113.tar.xz |
Btrfs: prevent loops in the directory tree when creating snapshots
For a directory tree:
/mnt/subvolA/subvolB
btrfsctl -s /mnt/subvolA/subvolB /mnt
Will create a directory loop with subvolA under subvolB. This
commit uses the forward refs for each subvol and snapshot to error out
before creating the loop.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Diffstat (limited to 'fs/btrfs/ioctl.c')
-rw-r--r-- | fs/btrfs/ioctl.c | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 536ae88..8828109 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -284,6 +284,56 @@ static noinline int btrfs_mksubvol(struct path *parent, char *name, * subvolume with specific mode bits. */ if (snap_src) { + struct dentry *dir = dentry->d_parent; + struct dentry *test = dir->d_parent; + struct btrfs_path *path = btrfs_alloc_path(); + int ret; + u64 test_oid; + u64 parent_oid = BTRFS_I(dir->d_inode)->root->root_key.objectid; + + test_oid = snap_src->root_key.objectid; + + ret = btrfs_find_root_ref(snap_src->fs_info->tree_root, + path, parent_oid, test_oid); + if (ret == 0) + goto create; + btrfs_release_path(snap_src->fs_info->tree_root, path); + + /* we need to make sure we aren't creating a directory loop + * by taking a snapshot of something that has our current + * subvol in its directory tree. So, this loops through + * the dentries and checks the forward refs for each subvolume + * to see if is references the subvolume where we are + * placing this new snapshot. + */ + while(1) { + if (!test || + dir == snap_src->fs_info->sb->s_root || + test == snap_src->fs_info->sb->s_root || + test->d_inode->i_sb != snap_src->fs_info->sb) { + break; + } + if (S_ISLNK(test->d_inode->i_mode)) { + printk("Symlink in snapshot path, failed\n"); + error = -EMLINK; + btrfs_free_path(path); + goto out_drop_write; + } + test_oid = + BTRFS_I(test->d_inode)->root->root_key.objectid; + ret = btrfs_find_root_ref(snap_src->fs_info->tree_root, + path, test_oid, parent_oid); + if (ret == 0) { + printk("Snapshot creation failed, looping\n"); + error = -EMLINK; + btrfs_free_path(path); + goto out_drop_write; + } + btrfs_release_path(snap_src->fs_info->tree_root, path); + test = test->d_parent; + } +create: + btrfs_free_path(path); error = create_snapshot(snap_src, dentry, name, namelen); } else { error = create_subvol(BTRFS_I(parent->dentry->d_inode)->root, |