On 2020-03-20 05:16, Jack Wang wrote:
> This is the sysfs interface to rnbd mapped devices on server side:
>
> /sys/devices/virtual/rnbd-server/ctl/devices/<device_name>/
> |- block_dev
> | *** link pointing to the corresponding block device sysfs entry
> |
> |- sessions/<session-name>/
> | *** sessions directory
> |
> |- read_only
> | *** is devices mapped as read only
> |
> |- mapping_path
> *** relative device path provided by the client during mapping
>
> +static struct kobj_type ktype = {
> + .sysfs_ops = &kobj_sysfs_ops,
> +};
>From Documentation/kobject.txt: "One important point cannot be
overstated: every kobject must have a release() method." I think this is
something that Greg KH feels very strongly about. Please fix this.
> +int rnbd_srv_create_dev_sysfs(struct rnbd_srv_dev *dev,
> + struct block_device *bdev,
> + const char *dir_name)
> +{
> + struct kobject *bdev_kobj;
> + int ret;
> +
> + ret = kobject_init_and_add(&dev->dev_kobj, &ktype,
> + rnbd_devs_kobj, dir_name);
> + if (ret)
> + return ret;
> +
> + ret = kobject_init_and_add(&dev->dev_sessions_kobj,
> + &ktype,
> + &dev->dev_kobj, "sessions");
> + if (ret)
> + goto err;
> +
> + bdev_kobj = &disk_to_dev(bdev->bd_disk)->kobj;
> + ret = sysfs_create_link(&dev->dev_kobj, bdev_kobj, "block_dev");
> + if (ret)
> + goto err2;
> +
> + return 0;
> +
> +err2:
> + kobject_put(&dev->dev_sessions_kobj);
> +err:
> + kobject_put(&dev->dev_kobj);
> + return ret;
> +}
Please choose more descriptive names for the goto labels, e.g.
put_sess_kobj and put_dev_kobj.
> +static ssize_t read_only_show(struct kobject *kobj, struct kobj_attribute *attr,
> + char *page)
> +{
> + struct rnbd_srv_sess_dev *sess_dev;
> +
> + sess_dev = container_of(kobj, struct rnbd_srv_sess_dev, kobj);
> +
> + return scnprintf(page, PAGE_SIZE, "%s\n",
> + (sess_dev->open_flags & FMODE_WRITE) ? "0" : "1");
> +}
The scnprintf() statement looks overcomplicated. How about the following?
return scnprintf(page, PAGE_SIZE, "%d\n",
(sess_dev->open_flags & FMODE_WRITE) != 0);
> +void rnbd_srv_destroy_dev_session_sysfs(struct rnbd_srv_sess_dev *sess_dev)
> +{
> + DECLARE_COMPLETION_ONSTACK(sysfs_compl);
> +
> + sysfs_remove_group(&sess_dev->kobj,
> + &rnbd_srv_default_dev_session_attr_group);
> +
> + sess_dev->sysfs_release_compl = &sysfs_compl;
> + kobject_del(&sess_dev->kobj);
> + kobject_put(&sess_dev->kobj);
> + wait_for_completion(&sysfs_compl);
> +}
Why is there a wait_for_completion() call in the above function? I think
Greg KH strongly disagrees with such calls in functions that remove
sysfs attributes.
> +int rnbd_srv_create_sysfs_files(void)
> +{
> + int err;
> +
> + rnbd_dev_class = class_create(THIS_MODULE, "rnbd-server");
> + if (IS_ERR(rnbd_dev_class))
> + return PTR_ERR(rnbd_dev_class);
> +
> + rnbd_dev = device_create(rnbd_dev_class, NULL,
> + MKDEV(0, 0), NULL, "ctl");
> + if (IS_ERR(rnbd_dev)) {
> + err = PTR_ERR(rnbd_dev);
> + goto cls_destroy;
> + }
> + rnbd_devs_kobj = kobject_create_and_add("devices", &rnbd_dev->kobj);
> + if (!rnbd_devs_kobj) {
> + err = -ENOMEM;
> + goto dev_destroy;
> + }
> +
> + return 0;
> +
> +dev_destroy:
> + device_destroy(rnbd_dev_class, MKDEV(0, 0));
> +cls_destroy:
> + class_destroy(rnbd_dev_class);
> +
> + return err;
> +}
Please mention the device class in the description of this patch.
Thanks,
Bart.
