block: remove support for the host aware zone model

When zones were first added the SCSI and ATA specs, two different
models were supported (in addition to the drive managed one that
is invisible to the host):

 - host managed where non-conventional zones there is strict requirement
   to write at the write pointer, or else an error is returned
 - host aware where a write point is maintained if writes always happen
   at it, otherwise it is left in an under-defined state and the
   sequential write preferred zones behave like conventional zones
   (probably very badly performing ones, though)

Not surprisingly this lukewarm model didn't prove to be very useful and
was finally removed from the ZBC and SBC specs (NVMe never implemented
it).  Due to to the easily disappearing write pointer host software
could never rely on the write pointer to actually be useful for say
recovery.

Fortunately only a few HDD prototypes shipped using this model which
never made it to mass production.  Drop the support before it is too
late.  Note that any such host aware prototype HDD can still be used
with Linux as we'll now treat it as a conventional HDD.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20231217165359.604246-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

3 files changed, 34 insertions, 54 deletions

diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index 6d8218a44122..d03d66f11493 100644
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -339,7 +339,7 @@ struct sdebug_dev_info {
 	bool used;
 
 	/* For ZBC devices */
-	enum blk_zoned_model zmodel;
+	bool zoned;
 	unsigned int zcap;
 	unsigned int zsize;
 	unsigned int zsize_shift;
@@ -844,8 +844,11 @@ static bool write_since_sync;
 static bool sdebug_statistics = DEF_STATISTICS;
 static bool sdebug_wp;
 static bool sdebug_allow_restart;
-/* Following enum: 0: no zbc, def; 1: host aware; 2: host managed */
-static enum blk_zoned_model sdeb_zbc_model = BLK_ZONED_NONE;
+static enum {
+	BLK_ZONED_NONE	= 0,
+	BLK_ZONED_HA	= 1,
+	BLK_ZONED_HM	= 2,
+} sdeb_zbc_model = BLK_ZONED_NONE;
 static char *sdeb_zbc_model_s;
 
 enum sam_lun_addr_method {SAM_LUN_AM_PERIPHERAL = 0x0,
@@ -1815,8 +1818,6 @@ static int inquiry_vpd_b1(struct sdebug_dev_info *devip, unsigned char *arr)
 	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;
 }
@@ -1883,7 +1884,7 @@ 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 = (devip->zmodel != BLK_ZONED_NONE);
+	is_zbc = devip->zoned;
 	is_disk_zbc = (is_disk || is_zbc);
 	have_wlun = scsi_is_wlun(scp->device->lun);
 	if (have_wlun)
@@ -2195,7 +2196,7 @@ static int resp_readcap16(struct scsi_cmnd *scp,
 	 * Since the scsi_debug READ CAPACITY implementation always reports the
 	 * total disk capacity, set RC BASIS = 1 for host-managed ZBC devices.
 	 */
-	if (devip->zmodel == BLK_ZONED_HM)
+	if (devip->zoned)
 		arr[12] |= 1 << 4;
 
 	arr[15] = sdebug_lowest_aligned & 0xff;
@@ -2648,7 +2649,7 @@ 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 = (devip->zmodel != BLK_ZONED_NONE);
+	is_zbc = devip->zoned;
 	if ((is_disk || is_zbc) && !dbd)
 		bd_len = llbaa ? 16 : 8;
 	else
@@ -3194,8 +3195,6 @@ static int check_zbc_access_params(struct scsi_cmnd *scp,
 	struct sdeb_zone_state *zsp_end = zbc_zone(devip, lba + num - 1);
 
 	if (!write) {
-		if (devip->zmodel == BLK_ZONED_HA)
-			return 0;
 		/* For host-managed, reads cannot cross zone types boundaries */
 		if (zsp->z_type != zsp_end->z_type) {
 			mk_sense_buffer(scp, ILLEGAL_REQUEST,
@@ -5322,7 +5321,7 @@ static int sdebug_device_create_zones(struct sdebug_dev_info *devip)
 	if (devip->zcap < devip->zsize)
 		devip->nr_zones += devip->nr_seq_zones;
 
-	if (devip->zmodel == BLK_ZONED_HM) {
+	if (devip->zoned) {
 		/* 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;
@@ -5347,7 +5346,7 @@ static int sdebug_device_create_zones(struct sdebug_dev_info *devip)
 			zsp->z_size =
 				min_t(u64, devip->zsize, capacity - zstart);
 		} else if ((zstart & (devip->zsize - 1)) == 0) {
-			if (devip->zmodel == BLK_ZONED_HM)
+			if (devip->zoned)
 				zsp->z_type = ZBC_ZTYPE_SWR;
 			else
 				zsp->z_type = ZBC_ZTYPE_SWP;
@@ -5390,13 +5389,13 @@ static struct sdebug_dev_info *sdebug_device_create(
 		}
 		devip->sdbg_host = sdbg_host;
 		if (sdeb_zbc_in_use) {
-			devip->zmodel = sdeb_zbc_model;
+			devip->zoned = sdeb_zbc_model == BLK_ZONED_HM;
 			if (sdebug_device_create_zones(devip)) {
 				kfree(devip);
 				return NULL;
 			}
 		} else {
-			devip->zmodel = BLK_ZONED_NONE;
+			devip->zoned = false;
 		}
 		devip->create_ts = ktime_get_boottime();
 		atomic_set(&devip->stopped, (sdeb_tur_ms_to_ready > 0 ? 2 : 0));
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index fa00dd503cbf..19a19eb277f5 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -3117,7 +3117,6 @@ static void sd_read_block_characteristics(struct scsi_disk *sdkp)
 	struct request_queue *q = sdkp->disk->queue;
 	struct scsi_vpd *vpd;
 	u16 rot;
-	u8 zoned;
 
 	rcu_read_lock();
 	vpd = rcu_dereference(sdkp->device->vpd_pgb1);
@@ -3128,7 +3127,7 @@ static void sd_read_block_characteristics(struct scsi_disk *sdkp)
 	}
 
 	rot = get_unaligned_be16(&vpd->data[4]);
-	zoned = (vpd->data[8] >> 4) & 3;
+	sdkp->zoned = (vpd->data[8] >> 4) & 3;
 	rcu_read_unlock();
 
 	if (rot == 1) {
@@ -3138,37 +3137,33 @@ static void sd_read_block_characteristics(struct scsi_disk *sdkp)
 
 	if (sdkp->device->type == TYPE_ZBC) {
 		/*
-		 * Host-managed: Per ZBC and ZAC specifications, writes in
-		 * sequential write required zones of host-managed devices must
-		 * be aligned to the device physical block size.
+		 * Host-managed.
+		 */
+		disk_set_zoned(sdkp->disk, true);
+
+		/*
+		 * Per ZBC and ZAC specifications, writes in sequential write
+		 * required zones of host-managed devices must be aligned to
+		 * the device physical block size.
 		 */
-		disk_set_zoned(sdkp->disk, BLK_ZONED_HM);
 		blk_queue_zone_write_granularity(q, sdkp->physical_block_size);
 	} else {
-		sdkp->zoned = zoned;
-		if (sdkp->zoned == 1) {
-			/* Host-aware */
-			disk_set_zoned(sdkp->disk, BLK_ZONED_HA);
-		} else {
-			/* Regular disk or drive managed disk */
-			disk_set_zoned(sdkp->disk, BLK_ZONED_NONE);
-		}
+		/*
+		 * Anything else.  This includes host-aware device that we treat
+		 * as conventional.
+		 */
+		disk_set_zoned(sdkp->disk, false);
 	}
 
 	if (!sdkp->first_scan)
 		return;
 
-	if (blk_queue_is_zoned(q)) {
-		sd_printk(KERN_NOTICE, sdkp, "Host-%s zoned block device\n",
-		      q->limits.zoned == BLK_ZONED_HM ? "managed" : "aware");
-	} else {
-		if (sdkp->zoned == 1)
-			sd_printk(KERN_NOTICE, sdkp,
-				  "Host-aware SMR disk used as regular disk\n");
-		else if (sdkp->zoned == 2)
-			sd_printk(KERN_NOTICE, sdkp,
-				  "Drive-managed SMR disk\n");
-	}
+	if (blk_queue_is_zoned(q))
+		sd_printk(KERN_NOTICE, sdkp, "Host-managed zoned block device\n");
+	else if (sdkp->zoned == 1)
+		sd_printk(KERN_NOTICE, sdkp, "Host-aware SMR disk used as regular disk\n");
+	else if (sdkp->zoned == 2)
+		sd_printk(KERN_NOTICE, sdkp, "Drive-managed SMR disk\n");
 }
 
 /**
diff --git a/drivers/scsi/sd_zbc.c b/drivers/scsi/sd_zbc.c
index a25215507668..26af5ab7d7c1 100644
--- a/drivers/scsi/sd_zbc.c
+++ b/drivers/scsi/sd_zbc.c
@@ -836,10 +836,7 @@ int sd_zbc_revalidate_zones(struct scsi_disk *sdkp)
 
 	/*
 	 * For all zoned disks, initialize zone append emulation data if not
-	 * already done. This is necessary also for host-aware disks used as
-	 * regular disks due to the presence of partitions as these partitions
-	 * may be deleted and the disk zoned model changed back from
-	 * BLK_ZONED_NONE to BLK_ZONED_HA.
+	 * already done.
 	 */
 	if (sd_is_zoned(sdkp) && !sdkp->zone_wp_update_buf) {
 		ret = sd_zbc_init_disk(sdkp);
@@ -932,17 +929,6 @@ int sd_zbc_read_zones(struct scsi_disk *sdkp, u8 buf[SD_BUF_SIZE])
 	sdkp->device->use_10_for_rw = 0;
 	sdkp->device->use_16_for_sync = 1;
 
-	if (!blk_queue_is_zoned(q)) {
-		/*
-		 * This can happen for a host aware disk with partitions.
-		 * The block device zone model was already cleared by
-		 * disk_set_zoned(). Only free the scsi disk zone
-		 * information and exit early.
-		 */
-		sd_zbc_free_zone_info(sdkp);
-		return 0;
-	}
-
 	/* Check zoned block device characteristics (unconstrained reads) */
 	ret = sd_zbc_check_zoned_characteristics(sdkp, buf);
 	if (ret)