+static ssize_t alias_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct gendisk *disk = dev_to_disk(dev);
+ ssize_t ret = 0;
+
+ if (disk->alias)
+ ret = snprintf(buf, ALIAS_LEN, "%s\n", disk->alias);
+ return ret;
+}
+
+static ssize_t alias_store(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct gendisk *disk = dev_to_disk(dev);
+ char *alias;
+ char *envp[] = { NULL, NULL };
+ unsigned char c;
+ int i;
+ ssize_t ret = count;
+
+ if (!count)
+ return -EINVAL;
+
+ if (count >= ALIAS_LEN) {
+ printk(KERN_ERR "alias: alias is too long\n");
+ return -EINVAL;
+ }
+
+ /* Validation check */
+ for (i = 0; i < count; i++) {
+ c = buf[i];
+ if (i == count - 1 && c == '\n')
+ break;
+ if (!isalnum(c) && c != '_' && c != '-') {
+ printk(KERN_ERR "alias: invalid alias\n");
+ return -EINVAL;
+ }
+ }
+
+ if (disk->alias) {
+ printk(KERN_INFO "alias: %s is already assigned (%s)\n",
+ disk->disk_name, disk->alias);
+ return -EINVAL;
+ }
+
+ alias = kasprintf(GFP_KERNEL, "%s", buf);
+ if (!alias)
+ return -ENOMEM;
+
+ if (alias[count - 1] == '\n')
+ alias[count - 1] = '\0';
+
+ envp[0] = kasprintf(GFP_KERNEL, "ALIAS=%s", alias);
+ if (!envp[0]) {
+ kfree(alias);
+ return -ENOMEM;
+ }
+
+ disk->alias = alias;
+ printk(KERN_INFO "alias: assigned %s to %s\n", alias, disk->disk_name);
+
+ kobject_uevent_env(&dev->kobj, KOBJ_ADD, envp);
+
+ kfree(envp[0]);
+ return ret;
+}
+