On 03/28/13 11:53, Wang Shilong wrote:
> From: Wang Shilong <wangsl-fnst@xxxxxxxxxxxxxx>
>
> This patch introduces mutex lock 'quota_lock', and makes
> all the user change for quota protected by quota_lock.
>
> Signed-off-by: Wang Shilong <wangsl-fnst@xxxxxxxxxxxxxx>
> Reviewed-by: Miao Xie <miaox@xxxxxxxxxxxxxx>
> ---
> fs/btrfs/ctree.h | 3 +++
> fs/btrfs/disk-io.c | 1 +
> fs/btrfs/ioctl.c | 16 ++++++++++++----
> 3 files changed, 16 insertions(+), 4 deletions(-)
>
> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
> index 6e81860..a11a8ed 100644
> --- a/fs/btrfs/ctree.h
> +++ b/fs/btrfs/ctree.h
> @@ -1584,6 +1584,9 @@ struct btrfs_fs_info {
> struct rb_root qgroup_tree;
> spinlock_t qgroup_lock;
>
> + /* protect user change operations for quota */
> + struct mutex quota_lock;
> +
> /* list of dirty qgroups to be written at next commit */
> struct list_head dirty_qgroups;
>
> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> index fe82d08..4552f14 100644
> --- a/fs/btrfs/disk-io.c
> +++ b/fs/btrfs/disk-io.c
> @@ -2250,6 +2250,7 @@ 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->quota_lock);
> fs_info->qgroup_tree = RB_ROOT;
> INIT_LIST_HEAD(&fs_info->dirty_qgroups);
> fs_info->qgroup_seq = 1;
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index 222ce84..e2950f1 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -752,7 +752,7 @@ static noinline int btrfs_mksubvol(struct path *parent,
>
> if (btrfs_root_refs(&BTRFS_I(dir)->root->root_item) == 0)
> goto out_up_read;
> -
> + mutex_lock(&BTRFS_I(dir)->root->fs_info->quota_lock);
> if (snap_src) {
> error = create_snapshot(snap_src, dir, dentry, name, namelen,
> async_transid, readonly, inherit);
> @@ -762,6 +762,7 @@ static noinline int btrfs_mksubvol(struct path *parent,
> }
> if (!error)
> fsnotify_mkdir(dir, dentry);
> + mutex_unlock(&BTRFS_I(dir)->root->fs_info->quota_lock);
You are completely serializing subvolume operations here. I'd prefer if
you'd move the lock to a lower level to only protect the quota
operations. Can't you move the lock completely to qgroup.c?
> out_up_read:
> up_read(&BTRFS_I(dir)->root->fs_info->subvol_sem);
> out_dput:
> @@ -3693,6 +3694,7 @@ static long btrfs_ioctl_quota_ctl(struct file *file, void __user *arg)
> goto drop_write;
> }
>
> + mutex_lock(&root->fs_info->quota_lock);
> down_read(&root->fs_info->subvol_sem);
> if (sa->cmd != BTRFS_QUOTA_CTL_RESCAN) {
> trans = btrfs_start_transaction(root, 2);
> @@ -3728,6 +3730,7 @@ static long btrfs_ioctl_quota_ctl(struct file *file, void __user *arg)
> out:
> kfree(sa);
> up_read(&root->fs_info->subvol_sem);
> + mutex_unlock(&root->fs_info->quota_lock);
> drop_write:
> mnt_drop_write_file(file);
> return ret;
> @@ -3754,6 +3757,7 @@ static long btrfs_ioctl_qgroup_assign(struct file *file, void __user *arg)
> goto drop_write;
> }
>
> + mutex_lock(&root->fs_info->quota_lock);
> trans = btrfs_join_transaction(root);
> if (IS_ERR(trans)) {
> ret = PTR_ERR(trans);
> @@ -3775,6 +3779,7 @@ static long btrfs_ioctl_qgroup_assign(struct file *file, void __user *arg)
>
> out:
> kfree(sa);
> + mutex_unlock(&root->fs_info->quota_lock);
> drop_write:
> mnt_drop_write_file(file);
> return ret;
> @@ -3805,11 +3810,11 @@ static long btrfs_ioctl_qgroup_create(struct file *file, void __user *arg)
> ret = -EINVAL;
> goto out;
> }
> -
> + mutex_lock(&root->fs_info->quota_lock);
> trans = btrfs_join_transaction(root);
> if (IS_ERR(trans)) {
> ret = PTR_ERR(trans);
> - goto out;
> + goto out_unlock;
> }
>
> /* FIXME: check if the IDs really exist */
> @@ -3824,6 +3829,8 @@ static long btrfs_ioctl_qgroup_create(struct file *file, void __user *arg)
> if (err && !ret)
> ret = err;
>
> +out_unlock:
> + mutex_unlock(&root->fs_info->quota_lock);
> out:
> kfree(sa);
> drop_write:
> @@ -3852,7 +3859,7 @@ static long btrfs_ioctl_qgroup_limit(struct file *file, void __user *arg)
> ret = PTR_ERR(sa);
> goto drop_write;
> }
> -
> + mutex_lock(&root->fs_info->quota_lock);
> trans = btrfs_join_transaction(root);
> if (IS_ERR(trans)) {
> ret = PTR_ERR(trans);
> @@ -3874,6 +3881,7 @@ static long btrfs_ioctl_qgroup_limit(struct file *file, void __user *arg)
>
> out:
> kfree(sa);
> + mutex_unlock(&root->fs_info->quota_lock);
> drop_write:
> mnt_drop_write_file(file);
> return ret;
>
--
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