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authorYan, Zheng <zheng.yan@oracle.com>2009-09-21 15:56:00 -0400
committerChris Mason <chris.mason@oracle.com>2009-09-21 15:56:00 -0400
commit4df27c4d5cc1dda54ed7d0a8389347f2df359cf9 (patch)
tree2008f348d28c6c19e31924ae4fb414ca929a01f1 /fs/btrfs/dir-item.c
parent13a8a7c8c47e542b3cdb45bec3f431f96af79361 (diff)
Btrfs: change how subvolumes are organized
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>
Diffstat (limited to 'fs/btrfs/dir-item.c')
-rw-r--r--fs/btrfs/dir-item.c47
1 files changed, 47 insertions, 0 deletions
diff --git a/fs/btrfs/dir-item.c b/fs/btrfs/dir-item.c
index 1d70236ba00c..f3a6075519cc 100644
--- a/fs/btrfs/dir-item.c
+++ b/fs/btrfs/dir-item.c
@@ -281,6 +281,53 @@ btrfs_lookup_dir_index_item(struct btrfs_trans_handle *trans,
return btrfs_match_dir_item_name(root, path, name, name_len);
}
+struct btrfs_dir_item *
+btrfs_search_dir_index_item(struct btrfs_root *root,
+ struct btrfs_path *path, u64 dirid,
+ const char *name, int name_len)
+{
+ struct extent_buffer *leaf;
+ struct btrfs_dir_item *di;
+ struct btrfs_key key;
+ u32 nritems;
+ int ret;
+
+ key.objectid = dirid;
+ key.type = BTRFS_DIR_INDEX_KEY;
+ key.offset = 0;
+
+ ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+ if (ret < 0)
+ return ERR_PTR(ret);
+
+ leaf = path->nodes[0];
+ nritems = btrfs_header_nritems(leaf);
+
+ while (1) {
+ if (path->slots[0] >= nritems) {
+ ret = btrfs_next_leaf(root, path);
+ if (ret < 0)
+ return ERR_PTR(ret);
+ if (ret > 0)
+ break;
+ leaf = path->nodes[0];
+ nritems = btrfs_header_nritems(leaf);
+ continue;
+ }
+
+ btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
+ if (key.objectid != dirid || key.type != BTRFS_DIR_INDEX_KEY)
+ break;
+
+ di = btrfs_match_dir_item_name(root, path, name, name_len);
+ if (di)
+ return di;
+
+ path->slots[0]++;
+ }
+ return NULL;
+}
+
struct btrfs_dir_item *btrfs_lookup_xattr(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct btrfs_path *path, u64 dir,