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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: Wang Shilong <wangsl-fnst@cn.fujitsu.com>
Reviewed-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
This commit is contained in:
Wang Shilong 2013-04-07 10:50:17 +00:00 committed by Josef Bacik
parent f2f6ed3d54
commit 58400fce5a
1 changed files with 6 additions and 21 deletions
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27
fs/btrfs/qgroup.c
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@ -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);