@@ -1748,13 +1748,57 @@ int btrfs_create_qgroup(struct btrfs_trans_handle *trans, u64 qgroupid)
return ret;
}
-static bool qgroup_has_usage(struct btrfs_qgroup *qgroup)
+/*
+ * Return 0 if we can not delete the qgroup (not empty or has children etc).
+ * Return >0 if we can delete the qgroup.
+ * Return <0 for other errors during tree search.
+ */
+static int can_delete_qgroup(struct btrfs_fs_info *fs_info,
+ struct btrfs_qgroup *qgroup)
{
- return (qgroup->rfer > 0 || qgroup->rfer_cmpr > 0 ||
- qgroup->excl > 0 || qgroup->excl_cmpr > 0 ||
- qgroup->rsv.values[BTRFS_QGROUP_RSV_DATA] > 0 ||
- qgroup->rsv.values[BTRFS_QGROUP_RSV_META_PREALLOC] > 0 ||
- qgroup->rsv.values[BTRFS_QGROUP_RSV_META_PERTRANS] > 0);
+ struct btrfs_key key;
+ struct btrfs_path *path;
+ int ret;
+
+ /*
+ * Squota would never be inconsistent, but there can still be
+ * case where a dropped subvolume still has qgroup numbers, and
+ * squota relies on such qgroup for future accounting.
+ *
+ * So for squota, do not allow dropping any non-zero qgroup.
+ */
+ if (btrfs_qgroup_mode(fs_info) == BTRFS_QGROUP_MODE_SIMPLE &&
+ (qgroup->rfer || qgroup->excl || qgroup->excl_cmpr ||
+ qgroup->rfer_cmpr))
+ return 0;
+
+ /* For higher level qgroup, we can only delete it if it has no child. */
+ if (btrfs_qgroup_level(qgroup->qgroupid)) {
+ if (!list_empty(&qgroup->members))
+ return 0;
+ return 1;
+ }
+
+ /*
+ * For level-0 qgroups, we can only delete it if it has no subvolume
+ * for it.
+ * This means even a subvolume is unlinked but not yet fully dropped,
+ * we can not delete the qgroup.
+ */
+ key.objectid = qgroup->qgroupid;
+ key.type = BTRFS_ROOT_ITEM_KEY;
+ key.offset = -1ULL;
+ path = btrfs_alloc_path();
+ if (!path)
+ return -ENOMEM;
+
+ ret = btrfs_find_root(fs_info->tree_root, &key, path, NULL, NULL);
+ btrfs_free_path(path);
+ /*
+ * The @ret from btrfs_find_root() exactly matches our definition for
+ * the return value, thus can be returned directly.
+ */
+ return ret;
}
int btrfs_remove_qgroup(struct btrfs_trans_handle *trans, u64 qgroupid)
@@ -1776,7 +1820,10 @@ int btrfs_remove_qgroup(struct btrfs_trans_handle *trans, u64 qgroupid)
goto out;
}
- if (is_fstree(qgroupid) && qgroup_has_usage(qgroup)) {
+ ret = can_delete_qgroup(fs_info, qgroup);
+ if (ret < 0)
+ goto out;
+ if (ret == 0) {
ret = -EBUSY;
goto out;
}
@@ -1801,6 +1848,36 @@ int btrfs_remove_qgroup(struct btrfs_trans_handle *trans, u64 qgroupid)
}
spin_lock(&fs_info->qgroup_lock);
+ /*
+ * Warn on reserved space. The subvolume should has no child nor
+ * corresponding subvolume.
+ * Thus its reserved space should all be zero, no matter if qgroup
+ * is consistent or the mode.
+ */
+ WARN_ON(qgroup->rsv.values[BTRFS_QGROUP_RSV_DATA] ||
+ qgroup->rsv.values[BTRFS_QGROUP_RSV_META_PREALLOC] ||
+ qgroup->rsv.values[BTRFS_QGROUP_RSV_META_PERTRANS]);
+ /*
+ * The same for rfer/excl numbers, but that's only if our qgroup is
+ * consistent and if it's in regular qgroup mode.
+ * For simple mode it's not as accurate thus we can hit non-zero values
+ * very frequently.
+ */
+ if (btrfs_qgroup_mode(fs_info) == BTRFS_QGROUP_MODE_FULL &&
+ !(fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT)) {
+ if (WARN_ON(qgroup->rfer || qgroup->excl ||
+ qgroup->rfer_cmpr || qgroup->excl_cmpr)) {
+ btrfs_warn_rl(fs_info,
+"to be deleted qgroup %u/%llu has non-zero numbers, rfer %llu rfer_cmpr %llu excl %llu excl_cmpr %llu",
+ btrfs_qgroup_level(qgroup->qgroupid),
+ btrfs_qgroup_subvolid(qgroup->qgroupid),
+ qgroup->rfer,
+ qgroup->rfer_cmpr,
+ qgroup->excl,
+ qgroup->excl_cmpr);
+ qgroup_mark_inconsistent(fs_info);
+ }
+ }
del_qgroup_rb(fs_info, qgroupid);
spin_unlock(&fs_info->qgroup_lock);