Commit f5a6b1c5 authored by Dongsheng Yang's avatar Dongsheng Yang Committed by Chris Mason
Browse files

btrfs: qgroup: allow to remove qgroup which has parent but no child. 



When a qgroup has parents but no child, it should be removable in
Theory I think. But currently, we can not remove it when it has
either parent or child.

Example:
	# btrfs quota enable /mnt
	# btrfs qgroup create 1/0 /mnt
	# btrfs qgroup create 2/0 /mnt
	# btrfs qgroup assign 1/0 2/0 /mnt
	# btrfs qgroup show -pcre /mnt
qgroupid rfer  excl  max_rfer max_excl parent  child
-------- ----  ----  -------- -------- ------  -----
0/5      16384 16384 0        0        ---     ---
1/0      0     0     0        0        2/0     ---
2/0      0     0     0        0        ---     1/0

At this time, there is no subvol or qgroup depending on it.
Just a qgroup 2/0 is its parent, but 2/0 can work well without
1/0. So I think 1/0 should be removalbe. But:
	# btrfs qgroup destroy 1/0 /mnt
ERROR: unable to destroy quota group: Device or resource busy

This patch remove the check of qgroup->parent in removing it,
then we can remove a qgroup when it has a parent.

Signed-off-by: default avatarDongsheng Yang <yangds.fnst@cn.fujitsu.com>
Signed-off-by: default avatarChris Mason <clm@fb.com>
parent 09870d27

fs/btrfs/qgroup.c

+25 −5
Original line number Diff line number Diff line
@@ -1048,7 +1048,7 @@ out: 
	return ret;

}



int btrfs_del_qgroup_relation(struct btrfs_trans_handle *trans,

int __del_qgroup_relation(struct btrfs_trans_handle *trans,

			      struct btrfs_fs_info *fs_info, u64 src, u64 dst)

{

	struct btrfs_root *quota_root;
@@ -1058,7 +1058,6 @@ int btrfs_del_qgroup_relation(struct btrfs_trans_handle *trans, 
	int ret = 0;

	int err;



	mutex_lock(&fs_info->qgroup_ioctl_lock);

	quota_root = fs_info->quota_root;

	if (!quota_root) {

		ret = -EINVAL;
@@ -1089,7 +1088,18 @@ exist: 
	del_relation_rb(fs_info, src, dst);

	spin_unlock(&fs_info->qgroup_lock);

out:

	return ret;

}



int btrfs_del_qgroup_relation(struct btrfs_trans_handle *trans,

			      struct btrfs_fs_info *fs_info, u64 src, u64 dst)

{

	int ret = 0;



	mutex_lock(&fs_info->qgroup_ioctl_lock);

	ret = __del_qgroup_relation(trans, fs_info, src, dst);

	mutex_unlock(&fs_info->qgroup_ioctl_lock);



	return ret;

}
@@ -1132,6 +1142,7 @@ int btrfs_remove_qgroup(struct btrfs_trans_handle *trans, 
{

	struct btrfs_root *quota_root;

	struct btrfs_qgroup *qgroup;

	struct btrfs_qgroup_list *list;

	int ret = 0;



	mutex_lock(&fs_info->qgroup_ioctl_lock);
@@ -1146,15 +1157,24 @@ int btrfs_remove_qgroup(struct btrfs_trans_handle *trans, 
		ret = -ENOENT;

		goto out;

	} else {

		/* check if there are no relations to this qgroup */

		if (!list_empty(&qgroup->groups) ||

		    !list_empty(&qgroup->members)) {

		/* check if there are no children of this qgroup */

		if (!list_empty(&qgroup->members)) {

			ret = -EBUSY;

			goto out;

		}

	}

	ret = del_qgroup_item(trans, quota_root, qgroupid);



	while (!list_empty(&qgroup->groups)) {

		list = list_first_entry(&qgroup->groups,

					struct btrfs_qgroup_list, next_group);

		ret = __del_qgroup_relation(trans, fs_info,

					   qgroupid,

					   list->group->qgroupid);

		if (ret)

			goto out;

	}



	spin_lock(&fs_info->qgroup_lock);

	del_qgroup_rb(quota_root->fs_info, qgroupid);

	spin_unlock(&fs_info->qgroup_lock);

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