Btrfs: maintain subvolume items in the UUID tree
When a new subvolume or snapshot is created, a new UUID item is added
to the UUID tree. Such items are removed when the subvolume is deleted.
The ioctl to set the received subvolume UUID is also touched and will
now also add this received UUID into the UUID tree together with the
ID of the subvolume. The latter is also done when read-only snapshots
are created which inherit all the send/receive information from the
parent subvolume.
User mode programs use the BTRFS_IOC_TREE_SEARCH ioctl to search and
read in the UUID tree.
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 82fb11a..8e75249 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -367,6 +367,13 @@
return 0;
}
+int btrfs_is_empty_uuid(u8 *uuid)
+{
+ static char empty_uuid[BTRFS_UUID_SIZE] = {0};
+
+ return !memcmp(uuid, empty_uuid, BTRFS_UUID_SIZE);
+}
+
static noinline int create_subvol(struct inode *dir,
struct dentry *dentry,
char *name, int namelen,
@@ -400,7 +407,7 @@
* of create_snapshot().
*/
ret = btrfs_subvolume_reserve_metadata(root, &block_rsv,
- 7, &qgroup_reserved, false);
+ 8, &qgroup_reserved, false);
if (ret)
return ret;
@@ -522,9 +529,14 @@
ret = btrfs_add_root_ref(trans, root->fs_info->tree_root,
objectid, root->root_key.objectid,
btrfs_ino(dir), index, name, namelen);
-
BUG_ON(ret);
+ ret = btrfs_uuid_tree_add(trans, root->fs_info->uuid_root,
+ root_item.uuid, BTRFS_UUID_KEY_SUBVOL,
+ objectid);
+ if (ret)
+ btrfs_abort_transaction(trans, root, ret);
+
fail:
trans->block_rsv = NULL;
trans->bytes_reserved = 0;
@@ -577,9 +589,10 @@
* 1 - root item
* 2 - root ref/backref
* 1 - root of snapshot
+ * 1 - UUID item
*/
ret = btrfs_subvolume_reserve_metadata(BTRFS_I(dir)->root,
- &pending_snapshot->block_rsv, 7,
+ &pending_snapshot->block_rsv, 8,
&pending_snapshot->qgroup_reserved,
false);
if (ret)
@@ -2235,6 +2248,27 @@
goto out_end_trans;
}
}
+
+ ret = btrfs_uuid_tree_rem(trans, root->fs_info->uuid_root,
+ dest->root_item.uuid, BTRFS_UUID_KEY_SUBVOL,
+ dest->root_key.objectid);
+ if (ret && ret != -ENOENT) {
+ btrfs_abort_transaction(trans, root, ret);
+ err = ret;
+ goto out_end_trans;
+ }
+ if (!btrfs_is_empty_uuid(dest->root_item.received_uuid)) {
+ ret = btrfs_uuid_tree_rem(trans, root->fs_info->uuid_root,
+ dest->root_item.received_uuid,
+ BTRFS_UUID_KEY_RECEIVED_SUBVOL,
+ dest->root_key.objectid);
+ if (ret && ret != -ENOENT) {
+ btrfs_abort_transaction(trans, root, ret);
+ err = ret;
+ goto out_end_trans;
+ }
+ }
+
out_end_trans:
trans->block_rsv = NULL;
trans->bytes_reserved = 0;
@@ -2446,7 +2480,6 @@
struct btrfs_fs_devices *fs_devices = root->fs_info->fs_devices;
int ret = 0;
char *s_uuid = NULL;
- char empty_uuid[BTRFS_UUID_SIZE] = {0};
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
@@ -2455,7 +2488,7 @@
if (IS_ERR(di_args))
return PTR_ERR(di_args);
- if (memcmp(empty_uuid, di_args->uuid, BTRFS_UUID_SIZE) != 0)
+ if (!btrfs_is_empty_uuid(di_args->uuid))
s_uuid = di_args->uuid;
mutex_lock(&fs_devices->device_list_mutex);
@@ -4292,6 +4325,7 @@
struct btrfs_trans_handle *trans;
struct timespec ct = CURRENT_TIME;
int ret = 0;
+ int received_uuid_changed;
ret = mnt_want_write_file(file);
if (ret < 0)
@@ -4321,7 +4355,11 @@
goto out;
}
- trans = btrfs_start_transaction(root, 1);
+ /*
+ * 1 - root item
+ * 2 - uuid items (received uuid + subvol uuid)
+ */
+ trans = btrfs_start_transaction(root, 3);
if (IS_ERR(trans)) {
ret = PTR_ERR(trans);
trans = NULL;
@@ -4332,6 +4370,14 @@
sa->rtime.sec = ct.tv_sec;
sa->rtime.nsec = ct.tv_nsec;
+ received_uuid_changed = memcmp(root_item->received_uuid, sa->uuid,
+ BTRFS_UUID_SIZE);
+ if (received_uuid_changed &&
+ !btrfs_is_empty_uuid(root_item->received_uuid))
+ btrfs_uuid_tree_rem(trans, root->fs_info->uuid_root,
+ root_item->received_uuid,
+ BTRFS_UUID_KEY_RECEIVED_SUBVOL,
+ root->root_key.objectid);
memcpy(root_item->received_uuid, sa->uuid, BTRFS_UUID_SIZE);
btrfs_set_root_stransid(root_item, sa->stransid);
btrfs_set_root_rtransid(root_item, sa->rtransid);
@@ -4344,12 +4390,22 @@
&root->root_key, &root->root_item);
if (ret < 0) {
btrfs_end_transaction(trans, root);
- trans = NULL;
goto out;
- } else {
- ret = btrfs_commit_transaction(trans, root);
- if (ret < 0)
+ }
+ if (received_uuid_changed && !btrfs_is_empty_uuid(sa->uuid)) {
+ ret = btrfs_uuid_tree_add(trans, root->fs_info->uuid_root,
+ sa->uuid,
+ BTRFS_UUID_KEY_RECEIVED_SUBVOL,
+ root->root_key.objectid);
+ if (ret < 0 && ret != -EEXIST) {
+ btrfs_abort_transaction(trans, root, ret);
goto out;
+ }
+ }
+ ret = btrfs_commit_transaction(trans, root);
+ if (ret < 0) {
+ btrfs_abort_transaction(trans, root, ret);
+ goto out;
}
ret = copy_to_user(arg, sa, sizeof(*sa));