+ unsigned char *buffer);
+static void scsi_disk_release(struct class_device *cdev);
+
+static const char *sd_cache_types[] = {
+ "write through", "none", "write back",
+ "write back, no read (daft)"
+};
+
+static ssize_t sd_store_cache_type(struct class_device *cdev, const char *buf,
+ size_t count)
+{
+ int i, ct = -1, rcd, wce, sp;
+ struct scsi_disk *sdkp = to_scsi_disk(cdev);
+ struct scsi_device *sdp = sdkp->device;
+ char buffer[64];
+ char *buffer_data;
+ struct scsi_mode_data data;
+ struct scsi_sense_hdr sshdr;
+ int len;
+
+ if (sdp->type != TYPE_DISK)
+ /* no cache control on RBC devices; theoretically they
+ * can do it, but there's probably so many exceptions
+ * it's not worth the risk */
+ return -EINVAL;
+
+ for (i = 0; i < ARRAY_SIZE(sd_cache_types); i++) {
+ const int len = strlen(sd_cache_types[i]);
+ if (strncmp(sd_cache_types[i], buf, len) == 0 &&
+ buf[len] == '\n') {
+ ct = i;
+ break;
+ }
+ }
+ if (ct < 0)
+ return -EINVAL;
+ rcd = ct & 0x01 ? 1 : 0;
+ wce = ct & 0x02 ? 1 : 0;
+ if (scsi_mode_sense(sdp, 0x08, 8, buffer, sizeof(buffer), SD_TIMEOUT,
+ SD_MAX_RETRIES, &data, NULL))
+ return -EINVAL;
+ len = min_t(size_t, sizeof(buffer), data.length - data.header_length -
+ data.block_descriptor_length);
+ buffer_data = buffer + data.header_length +
+ data.block_descriptor_length;
+ buffer_data[2] &= ~0x05;
+ buffer_data[2] |= wce << 2 | rcd;
+ sp = buffer_data[0] & 0x80 ? 1 : 0;
+
+ if (scsi_mode_select(sdp, 1, sp, 8, buffer_data, len, SD_TIMEOUT,
+ SD_MAX_RETRIES, &data, &sshdr)) {
+ if (scsi_sense_valid(&sshdr))
+ scsi_print_sense_hdr(sdkp->disk->disk_name, &sshdr);
+ return -EINVAL;
+ }
+ sd_revalidate_disk(sdkp->disk);
+ return count;
+}
+
+static ssize_t sd_store_allow_restart(struct class_device *cdev, const char *buf,
+ size_t count)
+{
+ struct scsi_disk *sdkp = to_scsi_disk(cdev);
+ struct scsi_device *sdp = sdkp->device;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EACCES;
+
+ if (sdp->type != TYPE_DISK)
+ return -EINVAL;
+
+ sdp->allow_restart = simple_strtoul(buf, NULL, 10);
+
+ return count;
+}
+
+static ssize_t sd_show_cache_type(struct class_device *cdev, char *buf)
+{
+ struct scsi_disk *sdkp = to_scsi_disk(cdev);
+ int ct = sdkp->RCD + 2*sdkp->WCE;
+
+ return snprintf(buf, 40, "%s\n", sd_cache_types[ct]);
+}
+
+static ssize_t sd_show_fua(struct class_device *cdev, char *buf)
+{
+ struct scsi_disk *sdkp = to_scsi_disk(cdev);
+
+ return snprintf(buf, 20, "%u\n", sdkp->DPOFUA);
+}
+
+static ssize_t sd_show_allow_restart(struct class_device *cdev, char *buf)
+{
+ struct scsi_disk *sdkp = to_scsi_disk(cdev);
+
+ return snprintf(buf, 40, "%d\n", sdkp->device->allow_restart);
+}
+
+static struct class_device_attribute sd_disk_attrs[] = {
+ __ATTR(cache_type, S_IRUGO|S_IWUSR, sd_show_cache_type,
+ sd_store_cache_type),
+ __ATTR(FUA, S_IRUGO, sd_show_fua, NULL),
+ __ATTR(allow_restart, S_IRUGO|S_IWUSR, sd_show_allow_restart,
+ sd_store_allow_restart),
+ __ATTR_NULL,
+};
+
+static struct class sd_disk_class = {
+ .name = "scsi_disk",
+ .owner = THIS_MODULE,
+ .release = scsi_disk_release,
+ .class_dev_attrs = sd_disk_attrs,
+};