sd: Implement support for ZBC devices

Implement ZBC support functions to setup zoned disks, both
host-managed and host-aware models. Only zoned disks that satisfy
the following conditions are supported:
1) All zones are the same size, with the exception of an eventual
   last smaller runt zone.
2) For host-managed disks, reads are unrestricted (reads are not
   failed due to zone or write pointer alignement constraints).
Zoned disks that do not satisfy these 2 conditions are setup with
a capacity of 0 to prevent their use.

The function sd_zbc_read_zones, called from sd_revalidate_disk,
checks that the device satisfies the above two constraints. This
function may also change the disk capacity previously set by
sd_read_capacity for devices reporting only the capacity of
conventional zones at the beginning of the LBA range (i.e. devices
reporting rc_basis set to 0).

The capacity message output was moved out of sd_read_capacity into
a new function sd_print_capacity to include this eventual capacity
change by sd_zbc_read_zones. This new function also includes a call
to sd_zbc_print_zones to display the number of zones and zone size
of the device.

Signed-off-by: Hannes Reinecke <hare@suse.de>

[Damien: * Removed zone cache support
         * Removed mapping of discard to reset write pointer command
         * Modified sd_zbc_read_zones to include checks that the
           device satisfies the kernel constraints
         * Implemeted REPORT ZONES setup and post-processing based
           on code from Shaun Tancheff <shaun.tancheff@seagate.com>
         * Removed confusing use of 512B sector units in functions
           interface]
Signed-off-by: Damien Le Moal <damien.lemoal@hgst.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Shaun Tancheff <shaun.tancheff@seagate.com>
Tested-by: Shaun Tancheff <shaun.tancheff@seagate.com>
Acked-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 642 insertions, 0 deletions

diff --git a/drivers/scsi/sd_zbc.c b/drivers/scsi/sd_zbc.c
new file mode 100644
index 000000000000..16d3fa62d8ac
--- /dev/null
+++ b/drivers/scsi/sd_zbc.c
@@ -0,0 +1,642 @@
+/*
+ * SCSI Zoned Block commands
+ *
+ * Copyright (C) 2014-2015 SUSE Linux GmbH
+ * Written by: Hannes Reinecke <hare@suse.de>
+ * Modified by: Damien Le Moal <damien.lemoal@hgst.com>
+ * Modified by: Shaun Tancheff <shaun.tancheff@seagate.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version
+ * 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; see the file COPYING.  If not, write to
+ * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139,
+ * USA.
+ *
+ */
+
+#include <linux/blkdev.h>
+
+#include <asm/unaligned.h>
+
+#include <scsi/scsi.h>
+#include <scsi/scsi_cmnd.h>
+#include <scsi/scsi_dbg.h>
+#include <scsi/scsi_device.h>
+#include <scsi/scsi_driver.h>
+#include <scsi/scsi_host.h>
+#include <scsi/scsi_eh.h>
+
+#include "sd.h"
+#include "scsi_priv.h"
+
+enum zbc_zone_type {
+	ZBC_ZONE_TYPE_CONV = 0x1,
+	ZBC_ZONE_TYPE_SEQWRITE_REQ,
+	ZBC_ZONE_TYPE_SEQWRITE_PREF,
+	ZBC_ZONE_TYPE_RESERVED,
+};
+
+enum zbc_zone_cond {
+	ZBC_ZONE_COND_NO_WP,
+	ZBC_ZONE_COND_EMPTY,
+	ZBC_ZONE_COND_IMP_OPEN,
+	ZBC_ZONE_COND_EXP_OPEN,
+	ZBC_ZONE_COND_CLOSED,
+	ZBC_ZONE_COND_READONLY = 0xd,
+	ZBC_ZONE_COND_FULL,
+	ZBC_ZONE_COND_OFFLINE,
+};
+
+/**
+ * Convert a zone descriptor to a zone struct.
+ */
+static void sd_zbc_parse_report(struct scsi_disk *sdkp,
+				u8 *buf,
+				struct blk_zone *zone)
+{
+	struct scsi_device *sdp = sdkp->device;
+
+	memset(zone, 0, sizeof(struct blk_zone));
+
+	zone->type = buf[0] & 0x0f;
+	zone->cond = (buf[1] >> 4) & 0xf;
+	if (buf[1] & 0x01)
+		zone->reset = 1;
+	if (buf[1] & 0x02)
+		zone->non_seq = 1;
+
+	zone->len = logical_to_sectors(sdp, get_unaligned_be64(&buf[8]));
+	zone->start = logical_to_sectors(sdp, get_unaligned_be64(&buf[16]));
+	zone->wp = logical_to_sectors(sdp, get_unaligned_be64(&buf[24]));
+	if (zone->type != ZBC_ZONE_TYPE_CONV &&
+	    zone->cond == ZBC_ZONE_COND_FULL)
+		zone->wp = zone->start + zone->len;
+}
+
+/**
+ * Issue a REPORT ZONES scsi command.
+ */
+static int sd_zbc_report_zones(struct scsi_disk *sdkp, unsigned char *buf,
+			       unsigned int buflen, sector_t lba)
+{
+	struct scsi_device *sdp = sdkp->device;
+	const int timeout = sdp->request_queue->rq_timeout;
+	struct scsi_sense_hdr sshdr;
+	unsigned char cmd[16];
+	unsigned int rep_len;
+	int result;
+
+	memset(cmd, 0, 16);
+	cmd[0] = ZBC_IN;
+	cmd[1] = ZI_REPORT_ZONES;
+	put_unaligned_be64(lba, &cmd[2]);
+	put_unaligned_be32(buflen, &cmd[10]);
+	memset(buf, 0, buflen);
+
+	result = scsi_execute_req(sdp, cmd, DMA_FROM_DEVICE,
+				  buf, buflen, &sshdr,
+				  timeout, SD_MAX_RETRIES, NULL);
+	if (result) {
+		sd_printk(KERN_ERR, sdkp,
+			  "REPORT ZONES lba %llu failed with %d/%d\n",
+			  (unsigned long long)lba,
+			  host_byte(result), driver_byte(result));
+		return -EIO;
+	}
+
+	rep_len = get_unaligned_be32(&buf[0]);
+	if (rep_len < 64) {
+		sd_printk(KERN_ERR, sdkp,
+			  "REPORT ZONES report invalid length %u\n",
+			  rep_len);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+int sd_zbc_setup_report_cmnd(struct scsi_cmnd *cmd)
+{
+	struct request *rq = cmd->request;
+	struct scsi_disk *sdkp = scsi_disk(rq->rq_disk);
+	sector_t lba, sector = blk_rq_pos(rq);
+	unsigned int nr_bytes = blk_rq_bytes(rq);
+	int ret;
+
+	WARN_ON(nr_bytes == 0);
+
+	if (!sd_is_zoned(sdkp))
+		/* Not a zoned device */
+		return BLKPREP_KILL;
+
+	ret = scsi_init_io(cmd);
+	if (ret != BLKPREP_OK)
+		return ret;
+
+	cmd->cmd_len = 16;
+	memset(cmd->cmnd, 0, cmd->cmd_len);
+	cmd->cmnd[0] = ZBC_IN;
+	cmd->cmnd[1] = ZI_REPORT_ZONES;
+	lba = sectors_to_logical(sdkp->device, sector);
+	put_unaligned_be64(lba, &cmd->cmnd[2]);
+	put_unaligned_be32(nr_bytes, &cmd->cmnd[10]);
+	/* Do partial report for speeding things up */
+	cmd->cmnd[14] = ZBC_REPORT_ZONE_PARTIAL;
+
+	cmd->sc_data_direction = DMA_FROM_DEVICE;
+	cmd->sdb.length = nr_bytes;
+	cmd->transfersize = sdkp->device->sector_size;
+	cmd->allowed = 0;
+
+	/*
+	 * Report may return less bytes than requested. Make sure
+	 * to report completion on the entire initial request.
+	 */
+	rq->__data_len = nr_bytes;
+
+	return BLKPREP_OK;
+}
+
+static void sd_zbc_report_zones_complete(struct scsi_cmnd *scmd,
+					 unsigned int good_bytes)
+{
+	struct request *rq = scmd->request;
+	struct scsi_disk *sdkp = scsi_disk(rq->rq_disk);
+	struct sg_mapping_iter miter;
+	struct blk_zone_report_hdr hdr;
+	struct blk_zone zone;
+	unsigned int offset, bytes = 0;
+	unsigned long flags;
+	u8 *buf;
+
+	if (good_bytes < 64)
+		return;
+
+	memset(&hdr, 0, sizeof(struct blk_zone_report_hdr));
+
+	sg_miter_start(&miter, scsi_sglist(scmd), scsi_sg_count(scmd),
+		       SG_MITER_TO_SG | SG_MITER_ATOMIC);
+
+	local_irq_save(flags);
+	while (sg_miter_next(&miter) && bytes < good_bytes) {
+
+		buf = miter.addr;
+		offset = 0;
+
+		if (bytes == 0) {
+			/* Set the report header */
+			hdr.nr_zones = min_t(unsigned int,
+					 (good_bytes - 64) / 64,
+					 get_unaligned_be32(&buf[0]) / 64);
+			memcpy(buf, &hdr, sizeof(struct blk_zone_report_hdr));
+			offset += 64;
+			bytes += 64;
+		}
+
+		/* Parse zone descriptors */
+		while (offset < miter.length && hdr.nr_zones) {
+			WARN_ON(offset > miter.length);
+			buf = miter.addr + offset;
+			sd_zbc_parse_report(sdkp, buf, &zone);
+			memcpy(buf, &zone, sizeof(struct blk_zone));
+			offset += 64;
+			bytes += 64;
+			hdr.nr_zones--;
+		}
+
+		if (!hdr.nr_zones)
+			break;
+
+	}
+	sg_miter_stop(&miter);
+	local_irq_restore(flags);
+}
+
+static inline sector_t sd_zbc_zone_sectors(struct scsi_disk *sdkp)
+{
+	return logical_to_sectors(sdkp->device, sdkp->zone_blocks);
+}
+
+static inline unsigned int sd_zbc_zone_no(struct scsi_disk *sdkp,
+					  sector_t sector)
+{
+	return sectors_to_logical(sdkp->device, sector) >> sdkp->zone_shift;
+}
+
+int sd_zbc_setup_reset_cmnd(struct scsi_cmnd *cmd)
+{
+	struct request *rq = cmd->request;
+	struct scsi_disk *sdkp = scsi_disk(rq->rq_disk);
+	sector_t sector = blk_rq_pos(rq);
+	sector_t block = sectors_to_logical(sdkp->device, sector);
+	unsigned int zno = block >> sdkp->zone_shift;
+
+	if (!sd_is_zoned(sdkp))
+		/* Not a zoned device */
+		return BLKPREP_KILL;
+
+	if (sdkp->device->changed)
+		return BLKPREP_KILL;
+
+	if (sector & (sd_zbc_zone_sectors(sdkp) - 1))
+		/* Unaligned request */
+		return BLKPREP_KILL;
+
+	/* Do not allow concurrent reset and writes */
+	if (sdkp->zones_wlock &&
+	    test_and_set_bit(zno, sdkp->zones_wlock))
+		return BLKPREP_DEFER;
+
+	cmd->cmd_len = 16;
+	memset(cmd->cmnd, 0, cmd->cmd_len);
+	cmd->cmnd[0] = ZBC_OUT;
+	cmd->cmnd[1] = ZO_RESET_WRITE_POINTER;
+	put_unaligned_be64(block, &cmd->cmnd[2]);
+
+	rq->timeout = SD_TIMEOUT;
+	cmd->sc_data_direction = DMA_NONE;
+	cmd->transfersize = 0;
+	cmd->allowed = 0;
+
+	return BLKPREP_OK;
+}
+
+int sd_zbc_setup_write_cmnd(struct scsi_cmnd *cmd)
+{
+	struct request *rq = cmd->request;
+	struct scsi_disk *sdkp = scsi_disk(rq->rq_disk);
+	sector_t sector = blk_rq_pos(rq);
+	sector_t zone_sectors = sd_zbc_zone_sectors(sdkp);
+	unsigned int zno = sd_zbc_zone_no(sdkp, sector);
+
+	/*
+	 * Note: Checks of the alignment of the write command on
+	 * logical blocks is done in sd.c
+	 */
+
+	/* Do not allow zone boundaries crossing on host-managed drives */
+	if (blk_queue_zoned_model(sdkp->disk->queue) == BLK_ZONED_HM &&
+	    (sector & (zone_sectors - 1)) + blk_rq_sectors(rq) > zone_sectors)
+		return BLKPREP_KILL;
+
+	/*
+	 * Do not issue more than one write at a time per
+	 * zone. This solves write ordering problems due to
+	 * the unlocking of the request queue in the dispatch
+	 * path in the non scsi-mq case. For scsi-mq, this
+	 * also avoids potential write reordering when multiple
+	 * threads running on different CPUs write to the same
+	 * zone (with a synchronized sequential pattern).
+	 */
+	if (sdkp->zones_wlock &&
+	    test_and_set_bit(zno, sdkp->zones_wlock))
+		return BLKPREP_DEFER;
+
+	return BLKPREP_OK;
+}
+
+static void sd_zbc_unlock_zone(struct request *rq)
+{
+	struct scsi_disk *sdkp = scsi_disk(rq->rq_disk);
+
+	if (sdkp->zones_wlock) {
+		unsigned int zno = sd_zbc_zone_no(sdkp, blk_rq_pos(rq));
+		WARN_ON_ONCE(!test_bit(zno, sdkp->zones_wlock));
+		clear_bit_unlock(zno, sdkp->zones_wlock);
+		smp_mb__after_atomic();
+	}
+}
+
+void sd_zbc_cancel_write_cmnd(struct scsi_cmnd *cmd)
+{
+	sd_zbc_unlock_zone(cmd->request);
+}
+
+void sd_zbc_complete(struct scsi_cmnd *cmd,
+		     unsigned int good_bytes,
+		     struct scsi_sense_hdr *sshdr)
+{
+	int result = cmd->result;
+	struct request *rq = cmd->request;
+
+	switch (req_op(rq)) {
+	case REQ_OP_WRITE:
+	case REQ_OP_WRITE_SAME:
+	case REQ_OP_ZONE_RESET:
+
+		/* Unlock the zone */
+		sd_zbc_unlock_zone(rq);
+
+		if (!result ||
+		    sshdr->sense_key != ILLEGAL_REQUEST)
+			break;
+
+		switch (sshdr->asc) {
+		case 0x24:
+			/*
+			 * INVALID FIELD IN CDB error: For a zone reset,
+			 * this means that a reset of a conventional
+			 * zone was attempted. Nothing to worry about in
+			 * this case, so be quiet about the error.
+			 */
+			if (req_op(rq) == REQ_OP_ZONE_RESET)
+				rq->cmd_flags |= REQ_QUIET;
+			break;
+		case 0x21:
+			/*
+			 * INVALID ADDRESS FOR WRITE error: It is unlikely that
+			 * retrying write requests failed with any kind of
+			 * alignement error will result in success. So don't.
+			 */
+			cmd->allowed = 0;
+			break;
+		}
+
+		break;
+
+	case REQ_OP_ZONE_REPORT:
+
+		if (!result)
+			sd_zbc_report_zones_complete(cmd, good_bytes);
+		break;
+
+	}
+}
+
+/**
+ * Read zoned block device characteristics (VPD page B6).
+ */
+static int sd_zbc_read_zoned_characteristics(struct scsi_disk *sdkp,
+					     unsigned char *buf)
+{
+
+	if (scsi_get_vpd_page(sdkp->device, 0xb6, buf, 64)) {
+		sd_printk(KERN_NOTICE, sdkp,
+			  "Unconstrained-read check failed\n");
+		return -ENODEV;
+	}
+
+	if (sdkp->device->type != TYPE_ZBC) {
+		/* Host-aware */
+		sdkp->urswrz = 1;
+		sdkp->zones_optimal_open = get_unaligned_be64(&buf[8]);
+		sdkp->zones_optimal_nonseq = get_unaligned_be64(&buf[12]);
+		sdkp->zones_max_open = 0;
+	} else {
+		/* Host-managed */
+		sdkp->urswrz = buf[4] & 1;
+		sdkp->zones_optimal_open = 0;
+		sdkp->zones_optimal_nonseq = 0;
+		sdkp->zones_max_open = get_unaligned_be64(&buf[16]);
+	}
+
+	return 0;
+}
+
+/**
+ * Check reported capacity.
+ */
+static int sd_zbc_check_capacity(struct scsi_disk *sdkp,
+				 unsigned char *buf)
+{
+	sector_t lba;
+	int ret;
+
+	if (sdkp->rc_basis != 0)
+		return 0;
+
+	/* Do a report zone to get the maximum LBA to check capacity */
+	ret = sd_zbc_report_zones(sdkp, buf, SD_BUF_SIZE, 0);
+	if (ret)
+		return ret;
+
+	/* The max_lba field is the capacity of this device */
+	lba = get_unaligned_be64(&buf[8]);
+	if (lba + 1 == sdkp->capacity)
+		return 0;
+
+	if (sdkp->first_scan)
+		sd_printk(KERN_WARNING, sdkp,
+			  "Changing capacity from %llu to max LBA+1 %llu\n",
+			  (unsigned long long)sdkp->capacity,
+			  (unsigned long long)lba + 1);
+	sdkp->capacity = lba + 1;
+
+	return 0;
+}
+
+#define SD_ZBC_BUF_SIZE 131072
+
+static int sd_zbc_check_zone_size(struct scsi_disk *sdkp)
+{
+	u64 zone_blocks;
+	sector_t block = 0;
+	unsigned char *buf;
+	unsigned char *rec;
+	unsigned int buf_len;
+	unsigned int list_length;
+	int ret;
+	u8 same;
+
+	sdkp->zone_blocks = 0;
+
+	/* Get a buffer */
+	buf = kmalloc(SD_ZBC_BUF_SIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	/* Do a report zone to get the same field */
+	ret = sd_zbc_report_zones(sdkp, buf, SD_ZBC_BUF_SIZE, 0);
+	if (ret)
+		goto out;
+
+	same = buf[4] & 0x0f;
+	if (same > 0) {
+		rec = &buf[64];
+		zone_blocks = get_unaligned_be64(&rec[8]);
+		goto out;
+	}
+
+	/*
+	 * Check the size of all zones: all zones must be of
+	 * equal size, except the last zone which can be smaller
+	 * than other zones.
+	 */
+	do {
+
+		/* Parse REPORT ZONES header */
+		list_length = get_unaligned_be32(&buf[0]) + 64;
+		rec = buf + 64;
+		if (list_length < SD_ZBC_BUF_SIZE)
+			buf_len = list_length;
+		else
+			buf_len = SD_ZBC_BUF_SIZE;
+
+		/* Parse zone descriptors */
+		while (rec < buf + buf_len) {
+			zone_blocks = get_unaligned_be64(&rec[8]);
+			if (sdkp->zone_blocks == 0) {
+				sdkp->zone_blocks = zone_blocks;
+			} else if (zone_blocks != sdkp->zone_blocks &&
+				   (block + zone_blocks < sdkp->capacity
+				    || zone_blocks > sdkp->zone_blocks)) {
+				zone_blocks = 0;
+				goto out;
+			}
+			block += zone_blocks;
+			rec += 64;
+		}
+
+		if (block < sdkp->capacity) {
+			ret = sd_zbc_report_zones(sdkp, buf,
+						  SD_ZBC_BUF_SIZE, block);
+			if (ret)
+				return ret;
+		}
+
+	} while (block < sdkp->capacity);
+
+	zone_blocks = sdkp->zone_blocks;
+
+out:
+	kfree(buf);
+
+	if (!zone_blocks) {
+		if (sdkp->first_scan)
+			sd_printk(KERN_NOTICE, sdkp,
+				  "Devices with non constant zone "
+				  "size are not supported\n");
+		return -ENODEV;
+	}
+
+	if (!is_power_of_2(zone_blocks)) {
+		if (sdkp->first_scan)
+			sd_printk(KERN_NOTICE, sdkp,
+				  "Devices with non power of 2 zone "
+				  "size are not supported\n");
+		return -ENODEV;
+	}
+
+	if (logical_to_sectors(sdkp->device, zone_blocks) > UINT_MAX) {
+		if (sdkp->first_scan)
+			sd_printk(KERN_NOTICE, sdkp,
+				  "Zone size too large\n");
+		return -ENODEV;
+	}
+
+	sdkp->zone_blocks = zone_blocks;
+
+	return 0;
+}
+
+static int sd_zbc_setup(struct scsi_disk *sdkp)
+{
+
+	/* chunk_sectors indicates the zone size */
+	blk_queue_chunk_sectors(sdkp->disk->queue,
+			logical_to_sectors(sdkp->device, sdkp->zone_blocks));
+	sdkp->zone_shift = ilog2(sdkp->zone_blocks);
+	sdkp->nr_zones = sdkp->capacity >> sdkp->zone_shift;
+	if (sdkp->capacity & (sdkp->zone_blocks - 1))
+		sdkp->nr_zones++;
+
+	if (!sdkp->zones_wlock) {
+		sdkp->zones_wlock = kcalloc(BITS_TO_LONGS(sdkp->nr_zones),
+					    sizeof(unsigned long),
+					    GFP_KERNEL);
+		if (!sdkp->zones_wlock)
+			return -ENOMEM;
+	}
+
+	return 0;
+}
+
+int sd_zbc_read_zones(struct scsi_disk *sdkp,
+		      unsigned char *buf)
+{
+	sector_t capacity;
+	int ret = 0;
+
+	if (!sd_is_zoned(sdkp))
+		/*
+		 * Device managed or normal SCSI disk,
+		 * no special handling required
+		 */
+		return 0;
+
+
+	/* Get zoned block device characteristics */
+	ret = sd_zbc_read_zoned_characteristics(sdkp, buf);
+	if (ret)
+		goto err;
+
+	/*
+	 * Check for unconstrained reads: host-managed devices with
+	 * constrained reads (drives failing read after write pointer)
+	 * are not supported.
+	 */
+	if (!sdkp->urswrz) {
+		if (sdkp->first_scan)
+			sd_printk(KERN_NOTICE, sdkp,
+			  "constrained reads devices are not supported\n");
+		ret = -ENODEV;
+		goto err;
+	}
+
+	/* Check capacity */
+	ret = sd_zbc_check_capacity(sdkp, buf);
+	if (ret)
+		goto err;
+	capacity = logical_to_sectors(sdkp->device, sdkp->capacity);
+
+	/*
+	 * Check zone size: only devices with a constant zone size (except
+	 * an eventual last runt zone) that is a power of 2 are supported.
+	 */
+	ret = sd_zbc_check_zone_size(sdkp);
+	if (ret)
+		goto err;
+
+	/* The drive satisfies the kernel restrictions: set it up */
+	ret = sd_zbc_setup(sdkp);
+	if (ret)
+		goto err;
+
+	return 0;
+
+err:
+	sdkp->capacity = 0;
+
+	return ret;
+}
+
+void sd_zbc_remove(struct scsi_disk *sdkp)
+{
+	kfree(sdkp->zones_wlock);
+	sdkp->zones_wlock = NULL;
+}
+
+void sd_zbc_print_zones(struct scsi_disk *sdkp)
+{
+	if (!sd_is_zoned(sdkp) || !sdkp->capacity)
+		return;
+
+	if (sdkp->capacity & (sdkp->zone_blocks - 1))
+		sd_printk(KERN_NOTICE, sdkp,
+			  "%u zones of %u logical blocks + 1 runt zone\n",
+			  sdkp->nr_zones - 1,
+			  sdkp->zone_blocks);
+	else
+		sd_printk(KERN_NOTICE, sdkp,
+			  "%u zones of %u logical blocks\n",
+			  sdkp->nr_zones,
+			  sdkp->zone_blocks);
+}