scsi: ufs: core: Use is_visible to control UFS unit descriptor sysfs nodes

UFS Boot and Device W-LUs do not have unit descriptors and RPMB does not
support WB. Use is_visible() to control which nodes are visible and which
are not.
Signed-off-by: Bean Huo <beanhuo@micron.com>
Link: https://lore.kernel.org/r/20221025222430.277768-4-beanhuo@iokpp.deReviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Arthur Simchaev <arthur.simchaev@wdc.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/ufs/core/ufs-sysfs.c

@@ -1285,9 +1285,27 @@ static struct attribute *ufs_sysfs_unit_descriptor[] = {
 	NULL,
 };
 
+static umode_t ufs_unit_descriptor_is_visible(struct kobject *kobj, struct attribute *attr, int n)
+{
+	struct device *dev = container_of(kobj, struct device, kobj);
+	struct scsi_device *sdev = to_scsi_device(dev);
+	u8 lun = ufshcd_scsi_to_upiu_lun(sdev->lun);
+	umode_t mode = attr->mode;
+
+	if (lun == UFS_UPIU_BOOT_WLUN || lun == UFS_UPIU_UFS_DEVICE_WLUN)
+		/* Boot and device WLUN have no unit descriptors */
+		mode = 0;
+	if (lun == UFS_UPIU_RPMB_WLUN && attr == &dev_attr_wb_buf_alloc_units.attr)
+		mode = 0;
+
+	return mode;
+}
+
+
 const struct attribute_group ufs_sysfs_unit_descriptor_group = {
 	.name = "unit_descriptor",
 	.attrs = ufs_sysfs_unit_descriptor,
+	.is_visible = ufs_unit_descriptor_is_visible,
 };
 
 static ssize_t dyn_cap_needed_attribute_show(struct device *dev,