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Commit 58400fce authored by Wang Shilong's avatar Wang Shilong Committed by Josef Bacik
Browse files

Btrfs: remove some unnecessary spin_lock usages 



We use mutex lock to protect all the user change operations.
So when we are calling find_qgroup_rb() to check whether qgroup
exists, we don't have to hold spin_lock.

Besides, when enabling/disabling quota, it must be single thread
when operations come here. spin lock must be firstly used to
clear quota_root when disabling quota, while enabling quota, spin
lock must be used to complete the last assign work.

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 f2f6ed3d

fs/btrfs/qgroup.c

+6 −21
Original line number Diff line number Diff line
@@ -98,7 +98,7 @@ struct btrfs_qgroup_list { 
	struct btrfs_qgroup *member;

};



/* must be called with qgroup_lock held */

/* must be called with qgroup_ioctl_lock held */

static struct btrfs_qgroup *find_qgroup_rb(struct btrfs_fs_info *fs_info,

					   u64 qgroupid)

{
@@ -792,13 +792,10 @@ int btrfs_quota_enable(struct btrfs_trans_handle *trans, 
	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;

		spin_unlock(&fs_info->qgroup_lock);

		goto out;

	}

	spin_unlock(&fs_info->qgroup_lock);



	/*

	 * initially create the quota tree
@@ -860,14 +857,11 @@ int btrfs_quota_enable(struct btrfs_trans_handle *trans, 
			if (ret)

				goto out_free_path;



			spin_lock(&fs_info->qgroup_lock);

			qgroup = add_qgroup_rb(fs_info, found_key.offset);

			if (IS_ERR(qgroup)) {

				spin_unlock(&fs_info->qgroup_lock);

				ret = PTR_ERR(qgroup);

				goto out_free_path;

			}

			spin_unlock(&fs_info->qgroup_lock);

		}

		ret = btrfs_next_item(tree_root, path);

		if (ret < 0)
@@ -882,13 +876,12 @@ int btrfs_quota_enable(struct btrfs_trans_handle *trans, 
	if (ret)

		goto out_free_path;



	spin_lock(&fs_info->qgroup_lock);

	qgroup = add_qgroup_rb(fs_info, BTRFS_FS_TREE_OBJECTID);

	if (IS_ERR(qgroup)) {

		spin_unlock(&fs_info->qgroup_lock);

		ret = PTR_ERR(qgroup);

		goto out_free_path;

	}

	spin_lock(&fs_info->qgroup_lock);

	fs_info->quota_root = quota_root;

	fs_info->pending_quota_state = 1;

	spin_unlock(&fs_info->qgroup_lock);
@@ -913,11 +906,9 @@ int btrfs_quota_disable(struct btrfs_trans_handle *trans, 
	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);

	if (!fs_info->quota_root)

		goto out;

	}

	spin_lock(&fs_info->qgroup_lock);

	fs_info->quota_enabled = 0;

	fs_info->pending_quota_state = 0;

	quota_root = fs_info->quota_root;
@@ -1060,16 +1051,13 @@ int btrfs_remove_qgroup(struct btrfs_trans_handle *trans, 
	}



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

	spin_lock(&fs_info->qgroup_lock);

	qgroup = find_qgroup_rb(fs_info, qgroupid);

	if (qgroup) {

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

			spin_unlock(&fs_info->qgroup_lock);

			ret = -EBUSY;

			goto out;

		}

	}

	spin_unlock(&fs_info->qgroup_lock);



	ret = del_qgroup_item(trans, quota_root, qgroupid);
@@ -1106,20 +1094,17 @@ int btrfs_limit_qgroup(struct btrfs_trans_handle *trans, 
		       (unsigned long long)qgroupid);

	}



	spin_lock(&fs_info->qgroup_lock);



	qgroup = find_qgroup_rb(fs_info, qgroupid);

	if (!qgroup) {

		ret = -ENOENT;

		goto unlock;

		goto out;

	}

	spin_lock(&fs_info->qgroup_lock);

	qgroup->lim_flags = limit->flags;

	qgroup->max_rfer = limit->max_rfer;

	qgroup->max_excl = limit->max_excl;

	qgroup->rsv_rfer = limit->rsv_rfer;

	qgroup->rsv_excl = limit->rsv_excl;



unlock:

	spin_unlock(&fs_info->qgroup_lock);

out:

	mutex_unlock(&fs_info->qgroup_ioctl_lock);