Re: [PATCH 7/7] scsi_debug: implement zbc host-aware emulation

Douglas Gilbert <dgilbert@xxxxxxxxxxxx> · Wed, 22 Apr 2020 12:46:13 -0400

On 2020-04-22 6:42 a.m., Damien Le Moal wrote:
Implement ZBC host-aware device model emulation. The main changes from
the host-managed emulation are the device type (TYPE_DISK is used),
relaxation of access checks for read and write operations and different
handling of a sequential write preferred zone write pointer as mandated
by the ZBC r05 specifications.

To facilitate the implementation and avoid a lot of "if" statement, the
zmodel field is added to the device information and the z_type field to
the zone state data structure.

Signed-off-by: Damien Le Moal <damien.lemoal@xxxxxxx>

This is an unexpected surprise and a chance to exercise previously untested
parts of my user space packages (sg3_utils and sdparm).

A small nit: draft ZBC-2 has added the Zoned Block Device Extension field
which should be set to 1 for host-aware (and 0 for host-managed). It is 0
in both cases at the moment which is strictly speaking correct as 0 is
defined as "not reported". IMO it is more correct to set it to 1 in the
host-aware case :-)

Ralph Weber failed in his attempt to get version strings thrown out at T10.
So we might consider adding a ZBC version descriptor in the host-aware and
host-managed case. [Version descriptors are in the standard INQUIRY
response.]

Wish list: it would be good if lsscsi could indicate in its one line per
device mode that a disk was actually a ZBC host-aware disk. lsscsi is
restricted to datamining in sysfs and some other locations that don't
need root permissions. So it does not issue any SCSI commands. To see a
disk is ZBC host-aware it needs access to the Block Device Characteristics
VPD page, but as far as I can see that is not loaded into sysfs at this
time. Hannes?

Tested-by: Douglas Gilbert <dgilbert@xxxxxxxxxxxx>

---
  drivers/scsi/scsi_debug.c | 148 ++++++++++++++++++++++++++------------
  1 file changed, 103 insertions(+), 45 deletions(-)

diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index 9279ac9bb98d..46cd4e64bb9c 100644
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -262,6 +262,13 @@ static const char *sdebug_version_date = "20200421";
  
  #define SDEB_XA_NOT_IN_USE XA_MARK_1
  
+/* Zone types (zbcr05 table 25) */
+enum sdebug_z_type {
+	ZBC_ZONE_TYPE_CNV	= 0x1,
+	ZBC_ZONE_TYPE_SWR	= 0x2,
+	ZBC_ZONE_TYPE_SWP	= 0x3,
+};
+
  /* enumeration names taken from table 26, zbcr05 */
  enum sdebug_z_cond {
  	ZBC_NOT_WRITE_POINTER	= 0x0,
@@ -275,7 +282,9 @@ enum sdebug_z_cond {
  };
  
  struct sdeb_zone_state {	/* ZBC: per zone state */
+	enum sdebug_z_type z_type;
  	enum sdebug_z_cond z_cond;
+	bool z_non_seq_resource;
  	unsigned int z_size;
  	sector_t z_start;
  	sector_t z_wp;
@@ -294,6 +303,7 @@ struct sdebug_dev_info {
  	bool used;
  
  	/* For ZBC devices */
+	enum blk_zoned_model zmodel;
  	unsigned int zsize;
  	unsigned int zsize_shift;
  	unsigned int nr_zones;
@@ -822,7 +832,7 @@ static int dix_reads;
  static int dif_errors;
  
  /* ZBC global data */
-static bool sdeb_zbc_in_use;		/* true when ptype=TYPE_ZBC [0x14] */
+static bool sdeb_zbc_in_use;	/* true for host-aware and host-managed disks */
  static int sdeb_zbc_zone_size_mb;
  static int sdeb_zbc_max_open = DEF_ZBC_MAX_OPEN_ZONES;
  static int sdeb_zbc_nr_conv = DEF_ZBC_NR_CONV_ZONES;
@@ -1500,13 +1510,15 @@ static int inquiry_vpd_b0(unsigned char *arr)
  }
  
  /* Block device characteristics VPD page (SBC-3) */
-static int inquiry_vpd_b1(unsigned char *arr)
+static int inquiry_vpd_b1(struct sdebug_dev_info *devip, unsigned char *arr)
  {
  	memset(arr, 0, 0x3c);
  	arr[0] = 0;
  	arr[1] = 1;	/* non rotating medium (e.g. solid state) */
  	arr[2] = 0;
  	arr[3] = 5;	/* less than 1.8" */
+	if (devip->zmodel == BLK_ZONED_HA)
+		arr[4] = 1 << 4;	/* zoned field = 01b */
  
  	return 0x3c;
  }
@@ -1543,7 +1555,7 @@ static int inquiry_vpd_b6(struct sdebug_dev_info *devip, unsigned char *arr)
  	 */
  	put_unaligned_be32(0xffffffff, &arr[4]);
  	put_unaligned_be32(0xffffffff, &arr[8]);
-	if (devip->max_open)
+	if (sdeb_zbc_model == BLK_ZONED_HM && devip->max_open)
  		put_unaligned_be32(devip->max_open, &arr[12]);
  	else
  		put_unaligned_be32(0xffffffff, &arr[12]);
@@ -1566,7 +1578,7 @@ static int resp_inquiry(struct scsi_cmnd *scp, struct sdebug_dev_info *devip)
  	if (! arr)
  		return DID_REQUEUE << 16;
  	is_disk = (sdebug_ptype == TYPE_DISK);
-	is_zbc = (sdebug_ptype == TYPE_ZBC);
+	is_zbc = (devip->zmodel != BLK_ZONED_NONE);
  	is_disk_zbc = (is_disk || is_zbc);
  	have_wlun = scsi_is_wlun(scp->device->lun);
  	if (have_wlun)
@@ -1611,7 +1623,7 @@ static int resp_inquiry(struct scsi_cmnd *scp, struct sdebug_dev_info *devip)
  				arr[n++] = 0xb1;  /* Block characteristics */
  				if (is_disk)
  					arr[n++] = 0xb2;  /* LB Provisioning */
-				else if (is_zbc)
+				if (is_zbc)
  					arr[n++] = 0xb6;  /* ZB dev. char. */
  			}
  			arr[3] = n - 4;	  /* number of supported VPD pages */
@@ -1660,7 +1672,7 @@ static int resp_inquiry(struct scsi_cmnd *scp, struct sdebug_dev_info *devip)
  			arr[3] = inquiry_vpd_b0(&arr[4]);
  		} else if (is_disk_zbc && 0xb1 == cmd[2]) { /* Block char. */
  			arr[1] = cmd[2];        /*sanity */
-			arr[3] = inquiry_vpd_b1(&arr[4]);
+			arr[3] = inquiry_vpd_b1(devip, &arr[4]);
  		} else if (is_disk && 0xb2 == cmd[2]) { /* LB Prov. */
  			arr[1] = cmd[2];        /*sanity */
  			arr[3] = inquiry_vpd_b2(&arr[4]);
@@ -2305,7 +2317,7 @@ static int resp_mode_sense(struct scsi_cmnd *scp,
  	msense_6 = (MODE_SENSE == cmd[0]);
  	llbaa = msense_6 ? false : !!(cmd[1] & 0x10);
  	is_disk = (sdebug_ptype == TYPE_DISK);
-	is_zbc = (sdebug_ptype == TYPE_ZBC);
+	is_zbc = (devip->zmodel != BLK_ZONED_NONE);
  	if ((is_disk || is_zbc) && !dbd)
  		bd_len = llbaa ? 16 : 8;
  	else
@@ -2656,7 +2668,7 @@ static struct sdeb_zone_state *zbc_zone(struct sdebug_dev_info *devip,
  
  static inline bool zbc_zone_is_conv(struct sdeb_zone_state *zsp)
  {
-	return zsp->z_cond == ZBC_NOT_WRITE_POINTER;
+	return zsp->z_type == ZBC_ZONE_TYPE_CNV;
  }
  
  static void zbc_close_zone(struct sdebug_dev_info *devip,
@@ -2732,13 +2744,42 @@ static void zbc_inc_wp(struct sdebug_dev_info *devip,
  		       unsigned long long lba, unsigned int num)
  {
  	struct sdeb_zone_state *zsp = zbc_zone(devip, lba);
+	unsigned long long n, end, zend = zsp->z_start + zsp->z_size;
  
  	if (zbc_zone_is_conv(zsp))
  		return;
  
-	zsp->z_wp += num;
-	if (zsp->z_wp >= zsp->z_start + zsp->z_size)
-		zsp->z_cond = ZC5_FULL;
+	if (zsp->z_type == ZBC_ZONE_TYPE_SWR) {
+		zsp->z_wp += num;
+		if (zsp->z_wp >= zend)
+			zsp->z_cond = ZC5_FULL;
+		return;
+	}
+
+	while (num) {
+		if (lba != zsp->z_wp)
+			zsp->z_non_seq_resource = true;
+
+		end = lba + num;
+		if (end >= zend) {
+			n = zend - lba;
+			zsp->z_wp = zend;
+		} else if (end > zsp->z_wp) {
+			n = num;
+			zsp->z_wp = end;
+		} else {
+			n = num;
+		}
+		if (zsp->z_wp >= zend)
+			zsp->z_cond = ZC5_FULL;
+
+		num -= n;
+		lba += n;
+		if (num) {
+			zsp++;
+			zend = zsp->z_start + zsp->z_size;
+		}
+	}
  }
  
  static int check_zbc_access_params(struct scsi_cmnd *scp,
@@ -2750,7 +2791,9 @@ static int check_zbc_access_params(struct scsi_cmnd *scp,
  	struct sdeb_zone_state *zsp_end = zbc_zone(devip, lba + num - 1);
  
  	if (!write) {
-		/* Reads cannot cross zone types boundaries */
+		if (devip->zmodel == BLK_ZONED_HA)
+			return 0;
+		/* For host-managed, reads cannot cross zone types boundaries */
  		if (zsp_end != zsp &&
  		    zbc_zone_is_conv(zsp) &&
  		    !zbc_zone_is_conv(zsp_end)) {
@@ -2773,25 +2816,27 @@ static int check_zbc_access_params(struct scsi_cmnd *scp,
  		return 0;
  	}
  
-	/* Writes cannot cross sequential zone boundaries */
-	if (zsp_end != zsp) {
-		mk_sense_buffer(scp, ILLEGAL_REQUEST,
-				LBA_OUT_OF_RANGE,
-				WRITE_BOUNDARY_ASCQ);
-		return check_condition_result;
-	}
-	/* Cannot write full zones */
-	if (zsp->z_cond == ZC5_FULL) {
-		mk_sense_buffer(scp, ILLEGAL_REQUEST,
-				INVALID_FIELD_IN_CDB, 0);
-		return check_condition_result;
-	}
-	/* Writes must be aligned to the zone WP */
-	if (lba != zsp->z_wp) {
-		mk_sense_buffer(scp, ILLEGAL_REQUEST,
-				LBA_OUT_OF_RANGE,
-				UNALIGNED_WRITE_ASCQ);
-		return check_condition_result;
+	if (zsp->z_type == ZBC_ZONE_TYPE_SWR) {
+		/* Writes cannot cross sequential zone boundaries */
+		if (zsp_end != zsp) {
+			mk_sense_buffer(scp, ILLEGAL_REQUEST,
+					LBA_OUT_OF_RANGE,
+					WRITE_BOUNDARY_ASCQ);
+			return check_condition_result;
+		}
+		/* Cannot write full zones */
+		if (zsp->z_cond == ZC5_FULL) {
+			mk_sense_buffer(scp, ILLEGAL_REQUEST,
+					INVALID_FIELD_IN_CDB, 0);
+			return check_condition_result;
+		}
+		/* Writes must be aligned to the zone WP */
+		if (lba != zsp->z_wp) {
+			mk_sense_buffer(scp, ILLEGAL_REQUEST,
+					LBA_OUT_OF_RANGE,
+					UNALIGNED_WRITE_ASCQ);
+			return check_condition_result;
+		}
  	}
  
  	/* Handle implicit open of closed and empty zones */
@@ -4312,13 +4357,16 @@ static int resp_report_zones(struct scsi_cmnd *scp,
  		case 0x06:
  		case 0x07:
  		case 0x10:
-		case 0x11:
  			/*
-			 * Read-only, offline, reset WP recommended and
-			 * non-seq-resource-used are not emulated: no zones
-			 * to report;
+			 * Read-only, offline, reset WP recommended are
+			 * not emulated: no zones to report;
  			 */
  			continue;
+		case 0x11:
+			/* non-seq-resource set */
+			if (!zsp->z_non_seq_resource)
+				continue;
+			break;
  		case 0x3f:
  			/* Not write pointer (conventional) zones */
  			if (!zbc_zone_is_conv(zsp))
@@ -4333,11 +4381,10 @@ static int resp_report_zones(struct scsi_cmnd *scp,
  
  		if (nrz < rep_max_zones) {
  			/* Fill zone descriptor */
-			if (zbc_zone_is_conv(zsp))
-				desc[0] = 0x1;
-			else
-				desc[0] = 0x2;
+			desc[0] = zsp->z_type;
  			desc[1] = zsp->z_cond << 4;
+			if (zsp->z_non_seq_resource)
+				desc[1] |= 1 << 1;
  			put_unaligned_be64((u64)zsp->z_size, desc + 8);
  			put_unaligned_be64((u64)zsp->z_start, desc + 16);
  			put_unaligned_be64((u64)zsp->z_wp, desc + 24);
@@ -4591,6 +4638,7 @@ static void zbc_rwp_zone(struct sdebug_dev_info *devip,
  	if (zsp->z_cond == ZC4_CLOSED)
  		devip->nr_closed--;
  
+	zsp->z_non_seq_resource = false;
  	zsp->z_wp = zsp->z_start;
  	zsp->z_cond = ZC1_EMPTY;
  }
@@ -4796,11 +4844,13 @@ static int sdebug_device_create_zones(struct sdebug_dev_info *devip)
  	}
  	devip->nr_conv_zones = sdeb_zbc_nr_conv;
  
-	/* zbc_max_open_zones can be 0, meaning "not reported" (no limit) */
-	if (sdeb_zbc_max_open >= devip->nr_zones - 1)
-		devip->max_open = (devip->nr_zones - 1) / 2;
-	else
-		devip->max_open = sdeb_zbc_max_open;
+	if (devip->zmodel == BLK_ZONED_HM) {
+		/* zbc_max_open_zones can be 0, meaning "not reported" */
+		if (sdeb_zbc_max_open >= devip->nr_zones - 1)
+			devip->max_open = (devip->nr_zones - 1) / 2;
+		else
+			devip->max_open = sdeb_zbc_max_open;
+	}
  
  	devip->zstate = kcalloc(devip->nr_zones,
  				sizeof(struct sdeb_zone_state), GFP_KERNEL);
@@ -4813,9 +4863,14 @@ static int sdebug_device_create_zones(struct sdebug_dev_info *devip)
  		zsp->z_start = zstart;
  
  		if (i < devip->nr_conv_zones) {
+			zsp->z_type = ZBC_ZONE_TYPE_CNV;
  			zsp->z_cond = ZBC_NOT_WRITE_POINTER;
  			zsp->z_wp = (sector_t)-1;
  		} else {
+			if (devip->zmodel == BLK_ZONED_HM)
+				zsp->z_type = ZBC_ZONE_TYPE_SWR;
+			else
+				zsp->z_type = ZBC_ZONE_TYPE_SWP;
  			zsp->z_cond = ZC1_EMPTY;
  			zsp->z_wp = zsp->z_start;
  		}
@@ -4851,10 +4906,13 @@ static struct sdebug_dev_info *sdebug_device_create(
  		}
  		devip->sdbg_host = sdbg_host;
  		if (sdeb_zbc_in_use) {
+			devip->zmodel = sdeb_zbc_model;
  			if (sdebug_device_create_zones(devip)) {
  				kfree(devip);
  				return NULL;
  			}
+		} else {
+			devip->zmodel = BLK_ZONED_NONE;
  		}
  		devip->sdbg_host = sdbg_host;
  		list_add_tail(&devip->dev_list, &sdbg_host->dev_info_list);
@@ -6566,12 +6624,12 @@ static int __init scsi_debug_init(void)
  		sdeb_zbc_model = k;
  		switch (sdeb_zbc_model) {
  		case BLK_ZONED_NONE:
+		case BLK_ZONED_HA:
  			sdebug_ptype = TYPE_DISK;
  			break;
  		case BLK_ZONED_HM:
  			sdebug_ptype = TYPE_ZBC;
  			break;
-		case BLK_ZONED_HA:
  		default:
  			pr_err("Invalid ZBC model\n");
  			return -EINVAL;








