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Commit f2f6ed3d authored by Wang Shilong's avatar Wang Shilong Committed by Josef Bacik
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Btrfs: introduce a mutex lock for btrfs quota operations 



The original code has one spin_lock 'qgroup_lock' to protect quota
configurations in memory. If we want to add a BTRFS_QGROUP_INFO_KEY,
it will be added to Btree firstly, and then update configurations in
memory,however, a race condition may happen between these operations.
For example:
	->add_qgroup_info_item()
		->add_qgroup_rb()

For the above case, del_qgroup_info_item() may happen just before
add_qgroup_rb().

What's worse, when we want to add a qgroup relation:
	->add_qgroup_relation_item()
		->add_qgroup_relations()

We don't have any checks whether 'src' and 'dst' exist before
add_qgroup_relation_item(), a race condition can also happen for
the above case.

To avoid race condition and have all the necessary checks, we introduce
a mutex lock 'qgroup_ioctl_lock', and we make all the user change operations
protected by the mutex lock.

Signed-off-by: default avatarWang Shilong <wangsl-fnst@cn.fujitsu.com>
Reviewed-by: default avatarMiao Xie <miaox@cn.fujitsu.com>
Signed-off-by: default avatarJosef Bacik <jbacik@fusionio.com>
parent 7708f029

fs/btrfs/ctree.h

+3 −0
Original line number Diff line number Diff line
@@ -1583,6 +1583,9 @@ struct btrfs_fs_info { 
	struct rb_root qgroup_tree;

	spinlock_t qgroup_lock;



	/* protect user change for quota operations */

	struct mutex qgroup_ioctl_lock;



	/* list of dirty qgroups to be written at next commit */

	struct list_head dirty_qgroups;

fs/btrfs/disk-io.c

+1 −0
Original line number Diff line number Diff line
@@ -2213,6 +2213,7 @@ int open_ctree(struct super_block *sb, 
	mutex_init(&fs_info->dev_replace.lock);



	spin_lock_init(&fs_info->qgroup_lock);

	mutex_init(&fs_info->qgroup_ioctl_lock);

	fs_info->qgroup_tree = RB_ROOT;

	INIT_LIST_HEAD(&fs_info->dirty_qgroups);

	fs_info->qgroup_seq = 1;

fs/btrfs/qgroup.c

+57 −25
Original line number Diff line number Diff line
@@ -791,6 +791,7 @@ int btrfs_quota_enable(struct btrfs_trans_handle *trans, 
	int ret = 0;

	int slot;



	mutex_lock(&fs_info->qgroup_ioctl_lock);

	spin_lock(&fs_info->qgroup_lock);

	if (fs_info->quota_root) {

		fs_info->pending_quota_state = 1;
@@ -900,6 +901,7 @@ int btrfs_quota_enable(struct btrfs_trans_handle *trans, 
		kfree(quota_root);

	}

out:

	mutex_unlock(&fs_info->qgroup_ioctl_lock);

	return ret;

}
@@ -910,10 +912,11 @@ int btrfs_quota_disable(struct btrfs_trans_handle *trans, 
	struct btrfs_root *quota_root;

	int ret = 0;



	mutex_lock(&fs_info->qgroup_ioctl_lock);

	spin_lock(&fs_info->qgroup_lock);

	if (!fs_info->quota_root) {

		spin_unlock(&fs_info->qgroup_lock);

		return 0;

		goto out;

	}

	fs_info->quota_enabled = 0;

	fs_info->pending_quota_state = 0;
@@ -922,8 +925,10 @@ int btrfs_quota_disable(struct btrfs_trans_handle *trans, 
	btrfs_free_qgroup_config(fs_info);

	spin_unlock(&fs_info->qgroup_lock);



	if (!quota_root)

		return -EINVAL;

	if (!quota_root) {

		ret = -EINVAL;

		goto out;

	}



	ret = btrfs_clean_quota_tree(trans, quota_root);

	if (ret)
@@ -944,6 +949,7 @@ int btrfs_quota_disable(struct btrfs_trans_handle *trans, 
	free_extent_buffer(quota_root->commit_root);

	kfree(quota_root);

out:

	mutex_unlock(&fs_info->qgroup_ioctl_lock);

	return ret;

}
@@ -959,24 +965,28 @@ int btrfs_add_qgroup_relation(struct btrfs_trans_handle *trans, 
	struct btrfs_root *quota_root;

	int ret = 0;



	mutex_lock(&fs_info->qgroup_ioctl_lock);

	quota_root = fs_info->quota_root;

	if (!quota_root)

		return -EINVAL;

	if (!quota_root) {

		ret = -EINVAL;

		goto out;

	}



	ret = add_qgroup_relation_item(trans, quota_root, src, dst);

	if (ret)

		return ret;

		goto out;



	ret = add_qgroup_relation_item(trans, quota_root, dst, src);

	if (ret) {

		del_qgroup_relation_item(trans, quota_root, src, dst);

		return ret;

		goto out;

	}



	spin_lock(&fs_info->qgroup_lock);

	ret = add_relation_rb(quota_root->fs_info, src, dst);

	spin_unlock(&fs_info->qgroup_lock);



out:

	mutex_unlock(&fs_info->qgroup_ioctl_lock);

	return ret;

}
@@ -987,9 +997,12 @@ 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)

		return -EINVAL;

	if (!quota_root) {

		ret = -EINVAL;

		goto out;

	}



	ret = del_qgroup_relation_item(trans, quota_root, src, dst);

	err = del_qgroup_relation_item(trans, quota_root, dst, src);
@@ -1000,7 +1013,8 @@ int btrfs_del_qgroup_relation(struct btrfs_trans_handle *trans, 
	del_relation_rb(fs_info, src, dst);



	spin_unlock(&fs_info->qgroup_lock);



out:

	mutex_unlock(&fs_info->qgroup_ioctl_lock);

	return ret;

}
@@ -1011,9 +1025,12 @@ int btrfs_create_qgroup(struct btrfs_trans_handle *trans, 
	struct btrfs_qgroup *qgroup;

	int ret = 0;



	mutex_lock(&fs_info->qgroup_ioctl_lock);

	quota_root = fs_info->quota_root;

	if (!quota_root)

		return -EINVAL;

	if (!quota_root) {

		ret = -EINVAL;

		goto out;

	}



	ret = add_qgroup_item(trans, quota_root, qgroupid);
@@ -1023,7 +1040,8 @@ int btrfs_create_qgroup(struct btrfs_trans_handle *trans, 


	if (IS_ERR(qgroup))

		ret = PTR_ERR(qgroup);



out:

	mutex_unlock(&fs_info->qgroup_ioctl_lock);

	return ret;

}
@@ -1034,9 +1052,12 @@ int btrfs_remove_qgroup(struct btrfs_trans_handle *trans, 
	struct btrfs_qgroup *qgroup;

	int ret = 0;



	mutex_lock(&fs_info->qgroup_ioctl_lock);

	quota_root = fs_info->quota_root;

	if (!quota_root)

		return -EINVAL;

	if (!quota_root) {

		ret = -EINVAL;

		goto out;

	}



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

	spin_lock(&fs_info->qgroup_lock);
@@ -1044,7 +1065,8 @@ int btrfs_remove_qgroup(struct btrfs_trans_handle *trans, 
	if (qgroup) {

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

			spin_unlock(&fs_info->qgroup_lock);

			return -EBUSY;

			ret = -EBUSY;

			goto out;

		}

	}

	spin_unlock(&fs_info->qgroup_lock);
@@ -1054,7 +1076,8 @@ int btrfs_remove_qgroup(struct btrfs_trans_handle *trans, 
	spin_lock(&fs_info->qgroup_lock);

	del_qgroup_rb(quota_root->fs_info, qgroupid);

	spin_unlock(&fs_info->qgroup_lock);



out:

	mutex_unlock(&fs_info->qgroup_ioctl_lock);

	return ret;

}
@@ -1062,12 +1085,16 @@ int btrfs_limit_qgroup(struct btrfs_trans_handle *trans, 
		       struct btrfs_fs_info *fs_info, u64 qgroupid,

		       struct btrfs_qgroup_limit *limit)

{

	struct btrfs_root *quota_root = fs_info->quota_root;

	struct btrfs_root *quota_root;

	struct btrfs_qgroup *qgroup;

	int ret = 0;



	if (!quota_root)

		return -EINVAL;

	mutex_lock(&fs_info->qgroup_ioctl_lock);

	quota_root = fs_info->quota_root;

	if (!quota_root) {

		ret = -EINVAL;

		goto out;

	}



	ret = update_qgroup_limit_item(trans, quota_root, qgroupid,

				       limit->flags, limit->max_rfer,
@@ -1094,7 +1121,8 @@ int btrfs_limit_qgroup(struct btrfs_trans_handle *trans, 


unlock:

	spin_unlock(&fs_info->qgroup_lock);



out:

	mutex_unlock(&fs_info->qgroup_ioctl_lock);

	return ret;

}
@@ -1392,11 +1420,14 @@ int btrfs_qgroup_inherit(struct btrfs_trans_handle *trans, 
	struct btrfs_qgroup *dstgroup;

	u32 level_size = 0;



	mutex_lock(&fs_info->qgroup_ioctl_lock);

	if (!fs_info->quota_enabled)

		return 0;

		goto out;



	if (!quota_root)

		return -EINVAL;

	if (!quota_root) {

		ret = -EINVAL;

		goto out;

	}



	/*

	 * create a tracking group for the subvol itself
@@ -1523,6 +1554,7 @@ int btrfs_qgroup_inherit(struct btrfs_trans_handle *trans, 
unlock:

	spin_unlock(&fs_info->qgroup_lock);

out:

	mutex_unlock(&fs_info->qgroup_ioctl_lock);

	return ret;

}