Skip to content

Commit

Permalink
scsi: sd: Translate data lifetime information
Browse files Browse the repository at this point in the history 
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>
Link: https://lore.kernel.org/r/20240130214911.1863909-12-bvanassche@acm.org
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
  • Loading branch information
@bvanassche @martinkpetersen
bvanassche authored and martinkpetersen committed Feb 27, 2024
1 parent 4977c0f commit 4f53138
Show file tree
Hide file tree
Showing 2 changed files with 98 additions and 4 deletions.
98 changes: 95 additions & 3 deletions drivers/scsi/sd.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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>
Expand Down Expand Up @@ -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->write_hint, (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;
Expand All @@ -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]);
Expand All @@ -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]);
Expand Down Expand Up @@ -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->write_hint) {
ret = sd_setup_rw10_cmnd(cmd, write, lba, nr_blocks,
protect | fua);
} else {
Expand Down Expand Up @@ -3001,6 +3028,70 @@ 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 int 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.
Expand Down Expand Up @@ -3481,6 +3572,7 @@ 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);
Expand Down
4 changes: 3 additions & 1 deletion drivers/scsi/sd.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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 */
Expand All @@ -151,7 +153,7 @@ struct scsi_disk {
unsigned urswrz : 1;
unsigned security : 1;
unsigned ignore_medium_access_errors : 1;
bool rscs : 1; /* reduced stream control support */
unsigned rscs : 1; /* reduced stream control support */
};
#define to_scsi_disk(obj) container_of(obj, struct scsi_disk, disk_dev)

Expand Down

0 comments on commit 4f53138

Please sign in to comment.