[PATCH v4 15/22] sg: add 8 byte SCSI LUN to sg_scsi_id

[Douglas Gilbert <dgilbert@interlog.com>]

The existing ioctl(SG_GET_SCSI_ID) fills a object of type
struct sg_scsi_id whose last field is int unused[2]. Add
an anonymous union with u8 scsi_lun[8] sharing those last
8 bytes. This patch will place the current device's full
LUN in the scsi_lun array using T10's preferred LUN
format (i.e. an array of 8 bytes) when
ioctl(SG_GET_SCSI_ID) is called.

Note that structure already contains a 'lun' field but that
is a 32 bit integer. Users of this upgrade should choose
the scsi_lun array field henceforth but existing code
can remain as it is and will get the same 'lun' value with
the version 3 or version 4 driver.

Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Douglas Gilbert <dgilbert@interlog.com>
---
 drivers/scsi/sg.c      | 6 ++++--
 include/uapi/scsi/sg.h | 5 ++++-
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 79eb9089dc2c..4470aa0b2168 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -1684,6 +1684,7 @@ static int
 sg_ctl_scsi_id(struct scsi_device *sdev, struct sg_fd *sfp, void __user *p)
 {
 	struct sg_scsi_id ss_id;
+	struct scsi_lun lun8b;
 
 	SG_LOG(3, sfp, "%s:    SG_GET_SCSI_ID\n", __func__);
 	ss_id.host_no = sdev->host->host_no;
@@ -1693,8 +1694,9 @@ sg_ctl_scsi_id(struct scsi_device *sdev, struct sg_fd *sfp, void __user *p)
 	ss_id.scsi_type = sdev->type;
 	ss_id.h_cmd_per_lun = sdev->host->cmd_per_lun;
 	ss_id.d_queue_depth = sdev->queue_depth;
-	ss_id.unused[0] = 0;
-	ss_id.unused[1] = 0;
+	int_to_scsilun(sdev->lun, &lun8b);
+	/* ss_id.scsi_lun is in an anonymous union with 'int unused[2]' */
+	memcpy(ss_id.scsi_lun, lun8b.scsi_lun, 8);
 	if (copy_to_user(p, &ss_id, sizeof(struct sg_scsi_id)))
 		return -EFAULT;
 	return 0;
diff --git a/include/uapi/scsi/sg.h b/include/uapi/scsi/sg.h
index e38d63e66cdb..2c9cb92b3515 100644
--- a/include/uapi/scsi/sg.h
+++ b/include/uapi/scsi/sg.h
@@ -135,7 +135,10 @@ typedef struct sg_scsi_id {
 	int scsi_type;	/* TYPE_... defined in scsi/scsi.h */
 	short h_cmd_per_lun;/* host (adapter) maximum commands per lun */
 	short d_queue_depth;/* device (or adapter) maximum queue length */
-	int unused[2];
+	union {
+		int unused[2];  /* as per version 3 driver */
+		__u8 scsi_lun[8];  /* full 8 byte SCSI LUN [in v4 driver] */
+	};
 } sg_scsi_id_t;
 
 /* For backward compatibility v4 driver yields at most SG_MAX_QUEUE of these */
-- 
2.23.0