Hello Arne,
I have sent a patch-set about btrfs quota,
would you please review them for me. Any comment is welcome.
Thanks,
Wang
> From: Wang Shilong <wangsl-f...@cn.fujitsu.com>
>
> This is one of most important reason why we introduce a mutex here,
> the previous code dosen't check 'src' and 'dst' before assigning/removing
> a qgroup relations. Without the mutex lock, and checks may leads
> a race conditon.
>
> Signed-off-by: Wang Shilong <wangsl-f...@cn.fujitsu.com>
> Reviewed-by: Miao Xie <mi...@cn.fujitsu.com>
> ---
> fs/btrfs/ioctl.c | 81 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
> 1 files changed, 80 insertions(+), 1 deletions(-)
>
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index 8a01326..1cd96f6 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -3735,6 +3735,82 @@ drop_write:
> return ret;
> }
>
> +static int may_qgroup_assign(struct btrfs_root *root,
> + struct btrfs_ioctl_qgroup_assign_args *sa)
> +{
> + int ret = 0;
> + struct btrfs_key key;
> + struct btrfs_path *path;
> +
> + if (!root->fs_info->quota_root)
> + return -EINVAL;
> +
> + path = btrfs_alloc_path();
> + if (!path) {
> + ret = -ENOMEM;
> + return ret;
> + }
> +
> + key.objectid = 0;
> + key.type = BTRFS_QGROUP_INFO_KEY;
> + key.offset = sa->src;
> + ret = btrfs_search_slot(NULL, root->fs_info->quota_root,
> + &key, path, 0, 0);
> + if (ret > 0)
> + ret = -ENOENT;
> + if (ret < 0)
> + goto out;
> +
> + btrfs_release_path(path);
> + key.objectid = 0;
> + key.type = BTRFS_QGROUP_INFO_KEY;
> + key.offset = sa->dst;
> + ret = btrfs_search_slot(NULL, root->fs_info->quota_root,
> + &key, path, 0, 0);
> + if (ret > 0)
> + ret = -ENOENT;
> + if (ret < 0)
> + goto out;
> +
> + btrfs_release_path(path);
> + key.objectid = sa->src;
> + key.type = BTRFS_QGROUP_RELATION_KEY;
> + key.offset = sa->dst;
> + ret = btrfs_search_slot(NULL, root->fs_info->quota_root,
> + &key, path, 0, 0);
> + if (sa->assign) {
> + if (!ret)
> + ret = -EEXIST;
> + if (ret < 0)
> + goto out;
> + } else {
> + if (ret > 0)
> + ret = -ENOENT;
> + if (ret < 0)
> + goto out;
> + }
> +
> + btrfs_release_path(path);
> + key.objectid = sa->dst;
> + key.type = BTRFS_QGROUP_RELATION_KEY;
> + key.offset = sa->src;
> + if (sa->assign) {
> + if (!ret)
> + ret = -EEXIST;
> + if (ret < 0)
> + goto out;
> + } else {
> + if (ret > 0)
> + ret = -ENOENT;
> + if (ret < 0)
> + goto out;
> + }
> + ret = 0;
> +out:
> + btrfs_free_path(path);
> + return ret;
> +}
> +
> static long btrfs_ioctl_qgroup_assign(struct file *file, void __user *arg)
> {
> struct btrfs_root *root = BTRFS_I(file_inode(file))->root;
> @@ -3757,13 +3833,16 @@ static long btrfs_ioctl_qgroup_assign(struct file
> *file, void __user *arg)
> }
>
> mutex_lock(&root->fs_info->quota_lock);
> + ret = may_qgroup_assign(root, sa);
> + if (ret)
> + goto out;
> +
> trans = btrfs_join_transaction(root);
> if (IS_ERR(trans)) {
> ret = PTR_ERR(trans);
> goto out;
> }
>
> - /* FIXME: check if the IDs really exist */
> if (sa->assign) {
> ret = btrfs_add_qgroup_relation(trans, root->fs_info,
> sa->src, sa->dst);
> --
> 1.7.7.6
>
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