On Mon, Aug 06, 2018 at 01:53:28PM +0900, Misono Tomohiro wrote:
>When qgroup is on, subvolume deletion does not remove qgroup items
>of the subvolume (qgroup info, limit, relation) from quota tree and
>they need to get removed manually by "btrfs qgroup destroy".
>
>Since level 0 qgroup cannot be used/inherited by any other subvolume,
>let's remove them automatically when subvolume is deleted
>(to be precise, when the subvolume root is dropped).
>
>Reviewed-by: Lu Fengqi <lufq.fnst@xxxxxxxxxxxxxx>
>Reviewed-by: Qu Wenruo <wqu@xxxxxxxx>
>Signed-off-by: Misono Tomohiro <misono.tomohiro@xxxxxxxxxxxxxx>
>---
>v2 -> v3:
> Use root->root_key.objectid instead of root->objectid
> Add Reviewed-by tag
>
>v1 -> v2:
> Move call of btrfs_remove_qgroup() from btrfs_delete_subvolume()
> to btrfs_snapshot_destroy() so that it will be called after the
> subvolume root is really dropped
>
> fs/btrfs/extent-tree.c | 16 ++++++++++++----
> 1 file changed, 12 insertions(+), 4 deletions(-)
>
>diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
>index 9e7b237b9547..48edf839ed2c 100644
>--- a/fs/btrfs/extent-tree.c
>+++ b/fs/btrfs/extent-tree.c
>@@ -8871,12 +8871,13 @@ int btrfs_drop_snapshot(struct btrfs_root *root,
> struct btrfs_root_item *root_item = &root->root_item;
> struct walk_control *wc;
> struct btrfs_key key;
>+ u64 objectid = root->root_key.objectid;
> int err = 0;
> int ret;
> int level;
> bool root_dropped = false;
>
>- btrfs_debug(fs_info, "Drop subvolume %llu", root->objectid);
>+ btrfs_debug(fs_info, "Drop subvolume %llu", objectid);
>
> path = btrfs_alloc_path();
> if (!path) {
>@@ -9030,7 +9031,7 @@ int btrfs_drop_snapshot(struct btrfs_root *root,
> goto out_end_trans;
> }
>
>- if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID) {
>+ if (objectid != BTRFS_TREE_RELOC_OBJECTID) {
> ret = btrfs_find_root(tree_root, &root->root_key, path,
> NULL, NULL);
> if (ret < 0) {
>@@ -9043,8 +9044,7 @@ int btrfs_drop_snapshot(struct btrfs_root *root,
> *
> * The most common failure here is just -ENOENT.
> */
>- btrfs_del_orphan_item(trans, tree_root,
>- root->root_key.objectid);
>+ btrfs_del_orphan_item(trans, tree_root, objectid);
> }
> }
>
>@@ -9056,6 +9056,14 @@ int btrfs_drop_snapshot(struct btrfs_root *root,
> btrfs_put_fs_root(root);
> }
> root_dropped = true;
>+
>+ /* Remove level-0 qgroup items since no other subvolume can use them */
>+ ret = btrfs_remove_qgroup(trans, objectid);
>+ if (ret && ret != -EINVAL && ret != -ENOENT) {
I'm sorry for missing the snapshot case. If it is a snapshot, then when
we remove the relevant qgroup, we will not be able to perform
quick_update_accounting(), and it will return 1. So we shouldn't abort
the transaction when the return value = 1.
btrfs_remove_qgroup
-> __del_qgroup_relation
-> quick_update_accounting << if qgroup->excl != qgroup->rfer; return 1
--
Thanks,
Lu
>+ btrfs_abort_transaction(trans, ret);
>+ err = ret;
>+ }
>+
> out_end_trans:
> btrfs_end_transaction_throttle(trans);
> out_free:
>--
>2.14.4
>
>
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