[PATCH v6 10/19] scsi: sd: set read/write commands CDL index

Niklas Cassel
2023-04-06T11:45:48Z

From: Damien Le Moal <damien.lemoal@opensource.wdc.com>

Introduce the command duration limits helper function sd_cdl_dld() to
set the DLD bits of READ/WRITE 16 and READ/WRITE 32 commands to
indicate to the device the command duration limit descriptor to apply
to the commands.

When command duration limits are enabled, sd_cdl_dld() obtains the
index of the descriptor to apply to the command using the hints field of
the request IO priority value (hints IOPRIO_HINT_DEV_DURATION_LIMIT_1 to
IOPRIO_HINT_DEV_DURATION_LIMIT_7).

If command duration limits is disabled (which is the default), the limit
index "0" is always used to indicate "no limit" for a command.

Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Co-developed-by: Niklas Cassel <niklas.cassel@wdc.com>
Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
---
drivers/scsi/sd.c | 40 ++++++++++++++++++++++++++++++++++------
1 file changed, 34 insertions(+), 6 deletions(-)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 2dc4223a4c97..c265b8cf2890 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1042,13 +1042,14 @@ static blk_status_t sd_setup_flush_cmnd(struct scsi_cmnd *cmd)

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 char flags, unsigned int dld)
{
cmd->cmd_len = SD_EXT_CDB_SIZE;
cmd->cmnd[0] = VARIABLE_LENGTH_CMD;
cmd->cmnd[7] = 0x18; /* Additional CDB len */
cmd->cmnd[9] = write ? WRITE_32 : READ_32;
cmd->cmnd[10] = flags;
+ cmd->cmnd[11] = dld & 0x07;
put_unaligned_be64(lba, &cmd->cmnd[12]);
put_unaligned_be32(lba, &cmd->cmnd[20]); /* Expected Indirect LBA */
put_unaligned_be32(nr_blocks, &cmd->cmnd[28]);
@@ -1058,12 +1059,12 @@ static blk_status_t sd_setup_rw32_cmnd(struct scsi_cmnd *cmd, bool write,

static blk_status_t sd_setup_rw16_cmnd(struct scsi_cmnd *cmd, bool write,
sector_t lba, unsigned int nr_blocks,
- unsigned char flags)
+ unsigned char flags, unsigned int dld)
{
cmd->cmd_len = 16;
cmd->cmnd[0] = write ? WRITE_16 : READ_16;
- cmd->cmnd[1] = flags;
- cmd->cmnd[14] = 0;
+ cmd->cmnd[1] = flags | ((dld >> 2) & 0x01);
+ cmd->cmnd[14] = (dld & 0x03) << 6;
cmd->cmnd[15] = 0;
put_unaligned_be64(lba, &cmd->cmnd[2]);
put_unaligned_be32(nr_blocks, &cmd->cmnd[10]);
@@ -1115,6 +1116,31 @@ static blk_status_t sd_setup_rw6_cmnd(struct scsi_cmnd *cmd, bool write,
return BLK_STS_OK;
}

+/*
+ * Check if a command has a duration limit set. If it does, and the target
+ * device supports CDL and the feature is enabled, return the limit
+ * descriptor index to use. Return 0 (no limit) otherwise.
+ */
+static int sd_cdl_dld(struct scsi_disk *sdkp, struct scsi_cmnd *scmd)
+{
+ struct scsi_device *sdp = sdkp->device;
+ int hint;
+
+ if (!sdp->cdl_supported || !sdp->cdl_enable)
+ return 0;
+
+ /*
+ * Use "no limit" if the request ioprio does not specify a duration
+ * limit hint.
+ */
+ hint = IOPRIO_PRIO_HINT(req_get_ioprio(scsi_cmd_to_rq(scmd)));
+ if (hint < IOPRIO_HINT_DEV_DURATION_LIMIT_1 ||
+ hint > IOPRIO_HINT_DEV_DURATION_LIMIT_7)
+ return 0;
+
+ return (hint - IOPRIO_HINT_DEV_DURATION_LIMIT_1) + 1;
+}
+
static blk_status_t sd_setup_read_write_cmnd(struct scsi_cmnd *cmd)
{
struct request *rq = scsi_cmd_to_rq(cmd);
@@ -1126,6 +1152,7 @@ static blk_status_t sd_setup_read_write_cmnd(struct scsi_cmnd *cmd)
unsigned int mask = logical_to_sectors(sdp, 1) - 1;
bool write = rq_data_dir(rq) == WRITE;
unsigned char protect, fua;
+ unsigned int dld;
blk_status_t ret;
unsigned int dif;
bool dix;
@@ -1175,6 +1202,7 @@ static blk_status_t sd_setup_read_write_cmnd(struct scsi_cmnd *cmd)
fua = rq->cmd_flags & REQ_FUA ? 0x8 : 0;
dix = scsi_prot_sg_count(cmd);
dif = scsi_host_dif_capable(cmd->device->host, sdkp->protection_type);
+ dld = sd_cdl_dld(sdkp, cmd);

if (dif || dix)
protect = sd_setup_protect_cmnd(cmd, dix, dif);
@@ -1183,10 +1211,10 @@ static blk_status_t sd_setup_read_write_cmnd(struct scsi_cmnd *cmd)

if (protect && sdkp->protection_type == T10_PI_TYPE2_PROTECTION) {
ret = sd_setup_rw32_cmnd(cmd, write, lba, nr_blocks,
- protect | fua);
+ protect | fua, dld);
} else if (sdp->use_16_for_rw || (nr_blocks > 0xffff)) {
ret = sd_setup_rw16_cmnd(cmd, write, lba, nr_blocks,
- protect | fua);
+ protect | fua, dld);
} else if ((nr_blocks > 0xff) || (lba > 0x1fffff) ||
sdp->use_10_for_rw || protect) {
ret = sd_setup_rw10_cmnd(cmd, write, lba, nr_blocks,
--
2.39.2