[PATCH v4 08/15] sd: Translate data lifetime information

Bart Van Assche
2023-11-14T21:42:25Z

Recently T10 standardized SBC constrained streams. This mechanism allows
to pass data lifetime information to SCSI devices in the group number
field. Add support for translating write hint information into a
permanent stream number in the sd driver. Use WRITE(10) instead of
WRITE(6) if data lifetime information is present because the WRITE(6)
command does not have a GROUP NUMBER field.

Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
drivers/scsi/sd.c | 98 +++++++++++++++++++++++++++++++++++++++++++++--
drivers/scsi/sd.h | 2 +
2 files changed, 97 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 56c4310a741b..61a59f9168bc 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -47,6 +47,7 @@
#include <linux/blkpg.h>
#include <linux/blk-pm.h>
#include <linux/delay.h>
+#include <linux/rw_hint.h>
#include <linux/major.h>
#include <linux/mutex.h>
#include <linux/string_helpers.h>
@@ -1080,12 +1081,38 @@ static blk_status_t sd_setup_flush_cmnd(struct scsi_cmnd *cmd)
return BLK_STS_OK;
}

+/**
+ * sd_group_number() - Compute the GROUP NUMBER field
+ * @cmd: SCSI command for which to compute the value of the six-bit GROUP NUMBER
+ * field.
+ *
+ * From SBC-5 r05 (https://www.t10.org/cgi-bin/ac.pl?t=f&f=sbc5r05.pdf):
+ * 0: no relative lifetime.
+ * 1: shortest relative lifetime.
+ * 2: second shortest relative lifetime.
+ * 3 - 0x3d: intermediate relative lifetimes.
+ * 0x3e: second longest relative lifetime.
+ * 0x3f: longest relative lifetime.
+ */
+static u8 sd_group_number(struct scsi_cmnd *cmd)
+{
+ const struct request *rq = scsi_cmd_to_rq(cmd);
+ struct scsi_disk *sdkp = scsi_disk(rq->q->disk);
+
+ if (!sdkp->rscs)
+ return 0;
+
+ return min3((u32)rq->lifetime, (u32)sdkp->permanent_stream_count,
+ 0x3fu);
+}
+
static blk_status_t sd_setup_rw32_cmnd(struct scsi_cmnd *cmd, bool write,
sector_t lba, unsigned int nr_blocks,
unsigned char flags, unsigned int dld)
{
cmd->cmd_len = SD_EXT_CDB_SIZE;
cmd->cmnd[0] = VARIABLE_LENGTH_CMD;
+ cmd->cmnd[6] = sd_group_number(cmd);
cmd->cmnd[7] = 0x18; /* Additional CDB len */
cmd->cmnd[9] = write ? WRITE_32 : READ_32;
cmd->cmnd[10] = flags;
@@ -1104,7 +1131,7 @@ static blk_status_t sd_setup_rw16_cmnd(struct scsi_cmnd *cmd, bool write,
cmd->cmd_len = 16;
cmd->cmnd[0] = write ? WRITE_16 : READ_16;
cmd->cmnd[1] = flags | ((dld >> 2) & 0x01);
- cmd->cmnd[14] = (dld & 0x03) << 6;
+ cmd->cmnd[14] = ((dld & 0x03) << 6) | sd_group_number(cmd);
cmd->cmnd[15] = 0;
put_unaligned_be64(lba, &cmd->cmnd[2]);
put_unaligned_be32(nr_blocks, &cmd->cmnd[10]);
@@ -1119,7 +1146,7 @@ static blk_status_t sd_setup_rw10_cmnd(struct scsi_cmnd *cmd, bool write,
cmd->cmd_len = 10;
cmd->cmnd[0] = write ? WRITE_10 : READ_10;
cmd->cmnd[1] = flags;
- cmd->cmnd[6] = 0;
+ cmd->cmnd[6] = sd_group_number(cmd);
cmd->cmnd[9] = 0;
put_unaligned_be32(lba, &cmd->cmnd[2]);
put_unaligned_be16(nr_blocks, &cmd->cmnd[7]);
@@ -1256,7 +1283,7 @@ static blk_status_t sd_setup_read_write_cmnd(struct scsi_cmnd *cmd)
ret = sd_setup_rw16_cmnd(cmd, write, lba, nr_blocks,
protect | fua, dld);
} else if ((nr_blocks > 0xff) || (lba > 0x1fffff) ||
- sdp->use_10_for_rw || protect) {
+ sdp->use_10_for_rw || protect || rq->lifetime) {
ret = sd_setup_rw10_cmnd(cmd, write, lba, nr_blocks,
protect | fua);
} else {
@@ -2996,6 +3023,70 @@ sd_read_cache_type(struct scsi_disk *sdkp, unsigned char *buffer)
sdkp->DPOFUA = 0;
}

+static bool sd_is_perm_stream(struct scsi_disk *sdkp, unsigned stream_id)
+{
+ u8 cdb[16] = { SERVICE_ACTION_IN_16, SAI_GET_STREAM_STATUS };
+ struct {
+ struct scsi_stream_status_header h;
+ struct scsi_stream_status s;
+ } buf;
+ struct scsi_device *sdev = sdkp->device;
+ struct scsi_sense_hdr sshdr;
+ const struct scsi_exec_args exec_args = {
+ .sshdr = &sshdr,
+ };
+ int res;
+
+ put_unaligned_be16(stream_id, &cdb[4]);
+ put_unaligned_be32(sizeof(buf), &cdb[10]);
+
+ res = scsi_execute_cmd(sdev, cdb, REQ_OP_DRV_IN, &buf, sizeof(buf),
+ SD_TIMEOUT, sdkp->max_retries, &exec_args);
+ if (res < 0)
+ return false;
+ if (scsi_status_is_check_condition(res) && scsi_sense_valid(&sshdr))
+ sd_print_sense_hdr(sdkp, &sshdr);
+ if (res)
+ return false;
+ if (get_unaligned_be32(&buf.h.len) < sizeof(struct scsi_stream_status))
+ return false;
+ return buf.h.stream_status[0].perm;
+}
+
+static void sd_read_io_hints(struct scsi_disk *sdkp, unsigned char *buffer)
+{
+ struct scsi_device *sdp = sdkp->device;
+ const struct scsi_io_group_descriptor *desc, *start, *end;
+ struct scsi_sense_hdr sshdr;
+ struct scsi_mode_data data;
+ int res;
+
+ res = scsi_mode_sense(sdp, /*dbd=*/0x8, /*modepage=*/0x0a,
+ /*subpage=*/0x05, buffer, SD_BUF_SIZE,
+ SD_TIMEOUT, sdkp->max_retries, &data, &sshdr);
+ if (res < 0)
+ return;
+ start = (void *)buffer + data.header_length + 16;
+ end = (void *)buffer + ALIGN_DOWN(data.header_length + data.length,
+ sizeof(*end));
+ /*
+ * From "SBC-5 Constrained Streams with Data Lifetimes": Device severs
+ * should assign the lowest numbered stream identifiers to permanent
+ * streams.
+ */
+ for (desc = start; desc < end; desc++)
+ if (!desc->st_enble || !sd_is_perm_stream(sdkp, desc - start))
+ break;
+ sdkp->permanent_stream_count = desc - start;
+ if (sdkp->rscs && sdkp->permanent_stream_count < 2)
+ sd_printk(KERN_INFO, sdkp,
+ "Unexpected: RSCS has been set and the permanent stream count is %u\n",
+ sdkp->permanent_stream_count);
+ else if (sdkp->permanent_stream_count)
+ sd_printk(KERN_INFO, sdkp, "permanent stream count = %d\n",
+ sdkp->permanent_stream_count);
+}
+
/*
* The ATO bit indicates whether the DIF application tag is available
* for use by the operating system.
@@ -3479,6 +3570,7 @@ static int sd_revalidate_disk(struct gendisk *disk)

sd_read_write_protect_flag(sdkp, buffer);
sd_read_cache_type(sdkp, buffer);
+ sd_read_io_hints(sdkp, buffer);
sd_read_app_tag_own(sdkp, buffer);
sd_read_write_same(sdkp, buffer);
sd_read_security(sdkp, buffer);
diff --git a/drivers/scsi/sd.h b/drivers/scsi/sd.h
index e4539122f2a2..16cf7c543ccf 100644
--- a/drivers/scsi/sd.h
+++ b/drivers/scsi/sd.h
@@ -125,6 +125,8 @@ struct scsi_disk {
unsigned int physical_block_size;
unsigned int max_medium_access_timeouts;
unsigned int medium_access_timed_out;
+ /* number of permanent streams */
+ u16 permanent_stream_count;
u8 media_present;
u8 write_prot;
u8 protection_type;/* Data Integrity Field */