[PATCH v6 18/20] scsi: scsi_debug: Implement the IO Advice Hints Grouping mode page

[Bart Van Assche <bvanassche@acm.org>]

Implement an IO Advice Hints Grouping mode page with three permanent
streams. A permanent stream is a stream for which the device server does
not allow closing or otherwise modifying the configuration of that
stream. The stream identifier enable (ST_ENBLE) bit specifies whether
the stream identifier may be used in the GROUP NUMBER field of SCSI
WRITE commands.

Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Douglas Gilbert <dgilbert@interlog.com>
Tested-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 drivers/scsi/scsi_debug.c | 61 +++++++++++++++++++++++++++++++++++++--
 1 file changed, 58 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index 4181d0d81224..4e18265a05da 100644
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -1975,7 +1975,11 @@ static int resp_inquiry(struct scsi_cmnd *scp, struct sdebug_dev_info *devip)
 				arr[4] = 0x5;   /* SPT: GRD_CHK:1, REF_CHK:1 */
 			else
 				arr[4] = 0x0;   /* no protection stuff */
-			arr[5] = 0x7;   /* head of q, ordered + simple q's */
+			/*
+			 * GROUP_SUP=1; HEADSUP=1 (HEAD OF QUEUE); ORDSUP=1
+			 * (ORDERED queuing); SIMPSUP=1 (SIMPLE queuing).
+			 */
+			arr[5] = 0x17;
 		} else if (0x87 == cmd[2]) { /* mode page policy */
 			arr[3] = 0x8;	/* number of following entries */
 			arr[4] = 0x2;	/* disconnect-reconnect mp */
@@ -2565,6 +2569,40 @@ static int resp_ctrl_m_pg(unsigned char *p, int pcontrol, int target)
 	return sizeof(ctrl_m_pg);
 }
 
+/* IO Advice Hints Grouping mode page */
+static int resp_grouping_m_pg(unsigned char *p, int pcontrol, int target)
+{
+	/* IO Advice Hints Grouping mode page */
+	struct grouping_m_pg {
+		u8 page_code;	/* OR 0x40 when subpage_code > 0 */
+		u8 subpage_code;
+		__be16 page_length;
+		u8 reserved[12];
+		struct scsi_io_group_descriptor descr[MAXIMUM_NUMBER_OF_STREAMS];
+	};
+	static const struct grouping_m_pg gr_m_pg = {
+		.page_code = 0xa | 0x40,
+		.subpage_code = 5,
+		.page_length = cpu_to_be16(sizeof(gr_m_pg) - 4),
+		.descr = {
+			{ .st_enble = 1 },
+			{ .st_enble = 1 },
+			{ .st_enble = 1 },
+			{ .st_enble = 1 },
+			{ .st_enble = 1 },
+			{ .st_enble = 0 },
+		}
+	};
+
+	BUILD_BUG_ON(sizeof(struct grouping_m_pg) !=
+		     16 + MAXIMUM_NUMBER_OF_STREAMS * 16);
+	memcpy(p, &gr_m_pg, sizeof(gr_m_pg));
+	if (1 == pcontrol) {
+		/* There are no changeable values so clear from byte 4 on. */
+		memset(p + 4, 0, sizeof(gr_m_pg) - 4);
+	}
+	return sizeof(gr_m_pg);
+}
 
 static int resp_iec_m_pg(unsigned char *p, int pcontrol, int target)
 {	/* Informational Exceptions control mode page for mode_sense */
@@ -2714,6 +2752,10 @@ static int resp_mode_sense(struct scsi_cmnd *scp,
 		ap = arr + offset;
 	}
 
+	/*
+	 * N.B. If len>0 before resp_*_pg() call, then form of that call should be:
+	 *        len += resp_*_pg(ap + len, pcontrol, target);
+	 */
 	switch (pcode) {
 	case 0x1:	/* Read-Write error recovery page, direct access */
 		if (subpcode > 0x0 && subpcode < 0xff)
@@ -2748,9 +2790,20 @@ static int resp_mode_sense(struct scsi_cmnd *scp,
 		}
 		break;
 	case 0xa:	/* Control Mode page, all devices */
-		if (subpcode > 0x0 && subpcode < 0xff)
+		switch (subpcode) {
+		case 0:
+			len = resp_ctrl_m_pg(ap, pcontrol, target);
+			break;
+		case 0x05:
+			len = resp_grouping_m_pg(ap, pcontrol, target);
+			break;
+		case 0xff:
+			len = resp_ctrl_m_pg(ap, pcontrol, target);
+			len += resp_grouping_m_pg(ap + len, pcontrol, target);
+			break;
+		default:
 			goto bad_subpcode;
-		len = resp_ctrl_m_pg(ap, pcontrol, target);
+		}
 		offset += len;
 		break;
 	case 0x19:	/* if spc==1 then sas phy, control+discover */
@@ -2784,6 +2837,8 @@ static int resp_mode_sense(struct scsi_cmnd *scp,
 			len += resp_caching_pg(ap + len, pcontrol, target);
 		}
 		len += resp_ctrl_m_pg(ap + len, pcontrol, target);
+		if (0xff == subpcode)
+			len += resp_grouping_m_pg(ap + len, pcontrol, target);
 		len += resp_sas_sf_m_pg(ap + len, pcontrol, target);
 		if (0xff == subpcode) {
 			len += resp_sas_pcd_m_spg(ap + len, pcontrol, target,