[PATCH v6 2/4] Add support for SCT Write Same

Shaun Tancheff
2016-08-22T04:23:19Z

SATA drives may support write same via SCT. This is useful
for setting the drive contents to a specific pattern (0's).

Translate a SCSI WRITE SAME 16 command to be either a DSM TRIM
command or an SCT Write Same command.

Based on the UNMAP flag:
- When set translate to DSM TRIM
- When not set translate to SCT Write Same

Signed-off-by: Shaun Tancheff <shaun.tancheff@seagate.com>
---
v6:
- Change to use sg_copy_from_buffer as per Christoph Hellwig <hch@lst.de>
v5:
- Addressed review comments
- Report support for ZBC only for zoned devices.
- kmap page during rewrite
- Fix unmap set to require trim or error, if not unmap then sct write
same or error.
v4:
- Added partial MAINTENANCE_IN opcode simulation
- Dropped all changes in drivers/scsi/*
- Changed to honor the UNMAP flag -> TRIM, no UNMAP -> SCT.
v3:
- Demux UNMAP/TRIM from WRITE SAME
v2:
- Remove fugly ata hacking from sd.c

drivers/ata/libata-scsi.c | 199 +++++++++++++++++++++++++++++++++++++++-------
include/linux/ata.h | 43 ++++++++++
2 files changed, 213 insertions(+), 29 deletions(-)

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 7990cb2..ebf1a04 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -1159,8 +1159,6 @@ static void ata_scsi_sdev_config(struct scsi_device *sdev)
{
sdev->use_10_for_rw = 1;
sdev->use_10_for_ms = 1;
- sdev->no_report_opcodes = 1;
- sdev->no_write_same = 1;

/* Schedule policy is determined by ->qc_defer() callback and
* it needs to see every deferred qc. Set dev_blocked to 1 to
@@ -3287,7 +3285,7 @@ static unsigned int ata_scsi_pass_thru(struct ata_queued_cmd *qc)
* @cmd: SCSI command being translated
* @num: Maximum number of entries (nominally 64).
* @sector: Starting sector
- * @count: Total Range of request
+ * @count: Total Range of request in logical sectors
*
* Rewrite the WRITE SAME descriptor to be a DSM TRIM little-endian formatted
* descriptor.
@@ -3330,6 +3328,45 @@ static unsigned int ata_format_dsm_trim_descr(struct scsi_cmnd *cmd, u32 num,
return used_bytes;
}

+/**
+ * ata_format_dsm_trim_descr() - SATL Write Same to ATA SCT Write Same
+ * @cmd: SCSI command being translated
+ * @lba: Starting sector
+ * @num: Number of logical sectors to be zero'd.
+ *
+ * Rewrite the WRITE SAME descriptor to be an SCT Write Same formatted
+ * descriptor.
+ * NOTE: Writes a pattern (0's) in the foreground.
+ * Large write-same requents can timeout.
+ */
+static void ata_format_sct_write_same(struct scsi_cmnd *cmd, u64 lba, u64 num)
+{
+ u16 *sctpg;
+ unsigned long flags;
+
+ spin_lock_irqsave(&ata_scsi_rbuf_lock, flags);
+ sctpg = ((void *)ata_scsi_rbuf);
+
+ put_unaligned_le16(0x0002, &sctpg[0]); /* SCT_ACT_WRITE_SAME */
+ put_unaligned_le16(0x0101, &sctpg[1]); /* WRITE PTRN FG */
+ put_unaligned_le64(lba, &sctpg[2]);
+ put_unaligned_le64(num, &sctpg[6]);
+ put_unaligned_le32(0u, &sctpg[10]);
+
+ sg_copy_from_buffer(scsi_sglist(cmd), scsi_sg_count(cmd), sctpg, 512);
+ spin_unlock_irqrestore(&ata_scsi_rbuf_lock, flags);
+}
+
+/**
+ * ata_scsi_write_same_xlat() - SATL Write Same to ATA SCT Write Same
+ * @qc: Command to be translated
+ *
+ * Translate a SCSI WRITE SAME command to be either a DSM TRIM command or
+ * an SCT Write Same command.
+ * Based on WRITE SAME has the UNMAP flag
+ * When set translate to DSM TRIM
+ * When clear translate to SCT Write Same
+ */
static unsigned int ata_scsi_write_same_xlat(struct ata_queued_cmd *qc)
{
struct ata_taskfile *tf = &qc->tf;
@@ -3342,6 +3379,7 @@ static unsigned int ata_scsi_write_same_xlat(struct ata_queued_cmd *qc)
u32 size;
u16 fp;
u8 bp = 0xff;
+ u8 unmap = cdb[1] & 0x8;

/* we may not issue DMA commands if no DMA mode is set */
if (unlikely(!dev->dma_mode))
@@ -3353,11 +3391,26 @@ static unsigned int ata_scsi_write_same_xlat(struct ata_queued_cmd *qc)
}
scsi_16_lba_len(cdb, &block, &n_block);

- /* for now we only support WRITE SAME with the unmap bit set */
- if (unlikely(!(cdb[1] & 0x8))) {
- fp = 1;
- bp = 3;
- goto invalid_fld;
+ if (unmap) {
+ /* If trim is not enabled the cmd is invalid. */
+ if ((dev->horkage & ATA_HORKAGE_NOTRIM) ||
+ !ata_id_has_trim(dev->id)) {
+ fp = 1;
+ bp = 3;
+ goto invalid_fld;
+ }
+ /* If the request is too large the cmd is invalid */
+ if (n_block > 0xffff * trmax) {
+ fp = 2;
+ goto invalid_fld;
+ }
+ } else {
+ /* If write same is not available the cmd is invalid */
+ if (!ata_id_sct_write_same(dev->id)) {
+ fp = 1;
+ bp = 3;
+ goto invalid_fld;
+ }
}

/*
@@ -3367,30 +3420,42 @@ static unsigned int ata_scsi_write_same_xlat(struct ata_queued_cmd *qc)
if (!scsi_sg_count(scmd))
goto invalid_param_len;

- if (n_block <= 0xffff * trmax) {
+ if (unmap) {
size = ata_format_dsm_trim_descr(scmd, trmax, block, n_block);
+ if (ata_ncq_enabled(dev) && ata_fpdma_dsm_supported(dev)) {
+ /* Newer devices support queued TRIM commands */
+ tf->protocol = ATA_PROT_NCQ;
+ tf->command = ATA_CMD_FPDMA_SEND;
+ tf->hob_nsect = ATA_SUBCMD_FPDMA_SEND_DSM & 0x1f;
+ tf->nsect = qc->tag << 3;
+ tf->hob_feature = (size / 512) >> 8;
+ tf->feature = size / 512;
+
+ tf->auxiliary = 1;
+ } else {
+ tf->protocol = ATA_PROT_DMA;
+ tf->hob_feature = 0;
+ tf->feature = ATA_DSM_TRIM;
+ tf->hob_nsect = (size / 512) >> 8;
+ tf->nsect = size / 512;
+ tf->command = ATA_CMD_DSM;
+ }
} else {
- fp = 2;
- goto invalid_fld;
- }
-
- if (ata_ncq_enabled(dev) && ata_fpdma_dsm_supported(dev)) {
- /* Newer devices support queued TRIM commands */
- tf->protocol = ATA_PROT_NCQ;
- tf->command = ATA_CMD_FPDMA_SEND;
- tf->hob_nsect = ATA_SUBCMD_FPDMA_SEND_DSM & 0x1f;
- tf->nsect = qc->tag << 3;
- tf->hob_feature = (size / 512) >> 8;
- tf->feature = size / 512;
+ ata_format_sct_write_same(scmd, block, n_block);

- tf->auxiliary = 1;
- } else {
- tf->protocol = ATA_PROT_DMA;
tf->hob_feature = 0;
- tf->feature = ATA_DSM_TRIM;
- tf->hob_nsect = (size / 512) >> 8;
- tf->nsect = size / 512;
- tf->command = ATA_CMD_DSM;
+ tf->feature = 0;
+ tf->hob_nsect = 0;
+ tf->nsect = 1;
+ tf->lbah = 0;
+ tf->lbam = 0;
+ tf->lbal = ATA_CMD_STANDBYNOW1;
+ tf->hob_lbah = 0;
+ tf->hob_lbam = 0;
+ tf->hob_lbal = 0;
+ tf->device = ATA_CMD_STANDBYNOW1;
+ tf->protocol = ATA_PROT_DMA;
+ tf->command = ATA_CMD_WRITE_LOG_DMA_EXT;
}

tf->flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE | ATA_TFLAG_LBA48 |
@@ -3414,6 +3479,76 @@ invalid_opcode:
}

/**
+ * ata_scsiop_maint_in - Simulate a subset of MAINTENANCE_IN
+ * @args: device MAINTENANCE_IN data / SCSI command of interest.
+ * @rbuf: Response buffer, to which simulated SCSI cmd output is sent.
+ *
+ * Yields a subset to satisfy scsi_report_opcode()
+ *
+ * LOCKING:
+ * spin_lock_irqsave(host lock)
+ */
+static unsigned int ata_scsiop_maint_in(struct ata_scsi_args *args, u8 *rbuf)
+{
+ struct ata_device *dev = args->dev;
+ u8 *cdb = args->cmd->cmnd;
+ u8 supported = 0;
+ unsigned int err = 0;
+
+ if (cdb[2] != 1) {
+ ata_dev_warn(dev, "invalid command format %d\n", cdb[2]);
+ err = 2;
+ goto out;
+ }
+ switch (cdb[3]) {
+ case INQUIRY:
+ case MODE_SENSE:
+ case MODE_SENSE_10:
+ case READ_CAPACITY:
+ case SERVICE_ACTION_IN_16:
+ case REPORT_LUNS:
+ case REQUEST_SENSE:
+ case SYNCHRONIZE_CACHE:
+ case REZERO_UNIT:
+ case SEEK_6:
+ case SEEK_10:
+ case TEST_UNIT_READY:
+ case SEND_DIAGNOSTIC:
+ case MAINTENANCE_IN:
+ case READ_6:
+ case READ_10:
+ case READ_16:
+ case WRITE_6:
+ case WRITE_10:
+ case WRITE_16:
+ case ATA_12:
+ case ATA_16:
+ case VERIFY:
+ case VERIFY_16:
+ case MODE_SELECT:
+ case MODE_SELECT_10:
+ case START_STOP:
+ supported = 3;
+ break;
+ case WRITE_SAME_16:
+ if (ata_id_sct_write_same(dev->id))
+ supported = 3;
+ break;
+ case ZBC_IN:
+ case ZBC_OUT:
+ if (ata_id_zoned_cap(dev->id) ||
+ dev->class == ATA_DEV_ZAC)
+ supported = 3;
+ break;
+ default:
+ break;
+ }
+out:
+ rbuf[1] = supported; /* supported */
+ return err;
+}
+
+/**
* ata_scsi_report_zones_complete - convert ATA output
* @qc: command structure returning the data
*
@@ -4193,6 +4328,13 @@ void ata_scsi_simulate(struct ata_device *dev, struct scsi_cmnd *cmd)
ata_scsi_invalid_field(dev, cmd, 1);
break;

+ case MAINTENANCE_IN:
+ if (scsicmd[1] == MI_REPORT_SUPPORTED_OPERATION_CODES)
+ ata_scsi_rbuf_fill(&args, ata_scsiop_maint_in);
+ else
+ ata_scsi_invalid_field(dev, cmd, 1);
+ break;
+
/* all other commands */
default:
ata_scsi_set_sense(dev, cmd, ILLEGAL_REQUEST, 0x20, 0x0);
@@ -4225,7 +4367,6 @@ int ata_scsi_add_hosts(struct ata_host *host, struct scsi_host_template *sht)
shost->max_lun = 1;
shost->max_channel = 1;
shost->max_cmd_len = 16;
- shost->no_write_same = 1;

/* Schedule policy is determined by ->qc_defer()
* callback and it needs to see every deferred qc.
diff --git a/include/linux/ata.h b/include/linux/ata.h
index 45a1d71..fdb1803 100644
--- a/include/linux/ata.h
+++ b/include/linux/ata.h
@@ -105,6 +105,7 @@ enum {
ATA_ID_CFA_KEY_MGMT = 162,
ATA_ID_CFA_MODES = 163,
ATA_ID_DATA_SET_MGMT = 169,
+ ATA_ID_SCT_CMD_XPORT = 206,
ATA_ID_ROT_SPEED = 217,
ATA_ID_PIO4 = (1 << 1),

@@ -789,6 +790,48 @@ static inline bool ata_id_sense_reporting_enabled(const u16 *id)
}

/**
+ *
+ * Word: 206 - SCT Command Transport
+ * 15:12 - Vendor Specific
+ * 11:6 - Reserved
+ * 5 - SCT Command Transport Data Tables supported
+ * 4 - SCT Command Transport Features Control supported
+ * 3 - SCT Command Transport Error Recovery Control supported
+ * 2 - SCT Command Transport Write Same supported
+ * 1 - SCT Command Transport Long Sector Access supported
+ * 0 - SCT Command Transport supported
+ */
+static inline bool ata_id_sct_data_tables(const u16 *id)
+{
+ return id[ATA_ID_SCT_CMD_XPORT] & (1 << 5) ? true : false;
+}
+
+static inline bool ata_id_sct_features_ctrl(const u16 *id)
+{
+ return id[ATA_ID_SCT_CMD_XPORT] & (1 << 4) ? true : false;
+}
+
+static inline bool ata_id_sct_error_recovery_ctrl(const u16 *id)
+{
+ return id[ATA_ID_SCT_CMD_XPORT] & (1 << 3) ? true : false;
+}
+
+static inline bool ata_id_sct_write_same(const u16 *id)
+{
+ return id[ATA_ID_SCT_CMD_XPORT] & (1 << 2) ? true : false;
+}
+
+static inline bool ata_id_sct_long_sector_access(const u16 *id)
+{
+ return id[ATA_ID_SCT_CMD_XPORT] & (1 << 1) ? true : false;
+}
+
+static inline bool ata_id_sct_supported(const u16 *id)
+{
+ return id[ATA_ID_SCT_CMD_XPORT] & (1 << 0) ? true : false;
+}
+
+/**
* ata_id_major_version - get ATA level of drive
* @id: Identify data
*
--
2.9.3