On 03/28/13 11:54, Wang Shilong wrote:
> From: Wang Shilong <wangsl-f...@cn.fujitsu.com>
>
> We use mutex_lock to protect all the user change operaions.
> 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 to here.Spin_lock must be fistly
> 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: Wang Shilong <wangsl-f...@cn.fujitsu.com>
> Reviewed-by: Miao Xie <mi...@cn.fujitsu.com>
> ---
> fs/btrfs/qgroup.c | 42 +++++++++++++++---------------------------
> 1 files changed, 15 insertions(+), 27 deletions(-)
>
> diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
> index e3598fa..7df372a 100644
> --- a/fs/btrfs/qgroup.c
> +++ b/fs/btrfs/qgroup.c
> @@ -42,7 +42,6 @@
> * - limit
> * - caches fuer ulists
> * - performance benchmarks
> - * - check all ioctl parameters
> */
>
> /*
> @@ -98,7 +97,11 @@ struct btrfs_qgroup_list {
> struct btrfs_qgroup *member;
> };
>
> -/* must be called with qgroup_lock held */
instead it must be called with quota_lock held. The rest looks
correct to me.
-Arne
> +/*
> + * don't need to be held by spin_lock since
> + * all the quota configurations on memory has been protected
> + * by mutex quota_lock.
> + */
> static struct btrfs_qgroup *find_qgroup_rb(struct btrfs_fs_info *fs_info,
> u64 qgroupid)
> {
> @@ -793,13 +796,10 @@ int btrfs_quota_enable(struct btrfs_trans_handle *trans,
> int ret = 0;
> int slot;
>
> - 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;
> + return ret;
> }
> - spin_unlock(&fs_info->qgroup_lock);
>
> /*
> * initially create the quota tree
> @@ -808,7 +808,7 @@ int btrfs_quota_enable(struct btrfs_trans_handle *trans,
> BTRFS_QUOTA_TREE_OBJECTID);
> if (IS_ERR(quota_root)) {
> ret = PTR_ERR(quota_root);
> - goto out;
> + return ret;
> }
>
> path = btrfs_alloc_path();
> @@ -861,14 +861,11 @@ 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)
> @@ -883,13 +880,12 @@ out_add_root:
> 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);
> @@ -901,7 +897,6 @@ out_free_root:
> free_extent_buffer(quota_root->commit_root);
> kfree(quota_root);
> }
> -out:
> return ret;
> }
>
> @@ -912,11 +907,10 @@ int btrfs_quota_disable(struct btrfs_trans_handle
> *trans,
> struct btrfs_root *quota_root;
> int ret = 0;
>
> - spin_lock(&fs_info->qgroup_lock);
> - if (!fs_info->quota_root) {
> - spin_unlock(&fs_info->qgroup_lock);
> + if (!fs_info->quota_root)
> return 0;
> - }
> +
> + spin_lock(&fs_info->qgroup_lock);
> fs_info->quota_enabled = 0;
> fs_info->pending_quota_state = 0;
> quota_root = fs_info->quota_root;
> @@ -1041,15 +1035,12 @@ int btrfs_remove_qgroup(struct btrfs_trans_handle
> *trans,
> return -EINVAL;
>
> /* 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);
> + if (!list_empty(&qgroup->groups) ||
> + !list_empty(&qgroup->members))
> return -EBUSY;
> - }
> }
> - spin_unlock(&fs_info->qgroup_lock);
>
> ret = del_qgroup_item(trans, quota_root, qgroupid);
>
> @@ -1081,20 +1072,17 @@ 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;
> + return ret;
> }
> + 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);
>
> return ret;
>
--
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