[BUG]
When a subvolume is created, we automatically create a level 0 qgroup
for it, but don't remove it when the subvolume is dropped.
Although it's not a big deal, it can easily pollute the output of
"btrfs qgroup show" and make it pretty annoying.
[FIX]
For btrfs_drop_snapshot(), if it's a valid subvolume (not a reloc tree)
and qgroup is enabled, we do the following work to remove the qgroup:
- Commit transaction
This is to ensure that the qgroup numbers of that subvolume is updated
properly (all number of that subvolume should be 0).
- Start a new transaction for later operation
- Call btrfs_remove_qgroup()
So that qgroup can be automatically removed when the subvolume get fully
dropped.
Signed-off-by: Qu Wenruo <wqu@xxxxxxxx>
---
fs/btrfs/extent-tree.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 49cb26fa7c63..5e8569cad16d 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -5182,6 +5182,7 @@ 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 rootid = root->root_key.objectid;
int err = 0;
int ret;
int level;
@@ -5384,6 +5385,30 @@ int btrfs_drop_snapshot(struct btrfs_root *root,
}
root_dropped = true;
out_end_trans:
+ /* If qgroup is enabled, also try to remove the qgroup */
+ if (test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags) && root_dropped &&
+ is_fstree(rootid) && !for_reloc) {
+ /* Commit transaction so qgroup numbers get updated to all 0 */
+ ret = btrfs_commit_transaction(trans);
+ if (ret < 0) {
+ btrfs_end_transaction_throttle(trans);
+ err = ret;
+ goto out_free;
+ }
+ trans = btrfs_start_transaction(fs_info->quota_root, 1);
+ if (IS_ERR(trans)) {
+ err = PTR_ERR(trans);
+ goto out_free;
+ }
+
+ /*
+ * Here we ignore the return value of btrfs_remove_qgroup(),
+ * as there is no critical error could happen.
+ * Error like EINVAL (quota disabled) or ENOENT (no such qgroup)
+ * are all safe to ignore.
+ */
+ btrfs_remove_qgroup(trans, rootid);
+ }
btrfs_end_transaction_throttle(trans);
out_free:
kfree(wc);
--
2.23.0
