Re: [PATCH v3 07/18] scsi: sd: detect support for command duration limits

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On 1/24/23 20:02, Niklas Cassel wrote:
From: Damien Le Moal <damien.lemoal@xxxxxxxxxxxxxxxxxx>

Detect if a disk supports command duration limits. Support for
the READ 16, WRITE 16, READ 32 and WRITE 32 commands is tested using
the function scsi_report_opcode(). For a disk supporting command
duration limits, the mode page indicating the command duration limits
descriptors that apply to the command is indicated using the rwcdlp
and cdlp bits.

Support duration limits is advertizes through sysfs using the new
"duration_limits" sysfs sub-directory of the generic device directory,
that is, /sys/block/sdX/device/duration_limits. Within this new
directory, the limit descriptors that apply to read and write operations
are exposed within the read and write directories, with descriptor
attributes grouped together in directories. The overall sysfs structure
created is:

/sys/block/sde/device/duration_limits/
├── perf_vs_duration_guideline
├── read
│   ├── 1
│   │   ├── duration_guideline
│   │   ├── duration_guideline_policy
│   │   ├── max_active_time
│   │   ├── max_active_time_policy
│   │   ├── max_inactive_time
│   │   └── max_inactive_time_policy
│   ├── 2
│   │   ├── duration_guideline
...
│   └── page
└── write
     ├── 1
     │   ├── duration_guideline
     │   ├── duration_guideline_policy
...

For each of the read and write descriptor directories, the page
attribute file indicate the command duration limit page providing the
descriptors. The possible values for the page attribute are "A", "B",
"T2A" and "T2B".

The new "duration_limits" attributes directory is added only for disks
that supports command duration limits.

Signed-off-by: Damien Le Moal <damien.lemoal@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Niklas Cassel <niklas.cassel@xxxxxxx>
---
  drivers/scsi/Makefile |   2 +-
  drivers/scsi/sd.c     |   2 +
  drivers/scsi/sd.h     |  61 ++++
  drivers/scsi/sd_cdl.c | 764 ++++++++++++++++++++++++++++++++++++++++++
  4 files changed, 828 insertions(+), 1 deletion(-)
  create mode 100644 drivers/scsi/sd_cdl.c

I'm not particularly happy with having sysfs reflect user settings, but every other place I can think of is even more convoluted.
So there.

diff --git a/drivers/scsi/Makefile b/drivers/scsi/Makefile
index f055bfd54a68..0e48cb6d21d6 100644
--- a/drivers/scsi/Makefile
+++ b/drivers/scsi/Makefile
@@ -170,7 +170,7 @@ scsi_mod-$(CONFIG_BLK_DEV_BSG)	+= scsi_bsg.o
hv_storvsc-y := storvsc_drv.o -sd_mod-objs := sd.o
+sd_mod-objs	:= sd.o sd_cdl.o
  sd_mod-$(CONFIG_BLK_DEV_INTEGRITY) += sd_dif.o
  sd_mod-$(CONFIG_BLK_DEV_ZONED) += sd_zbc.o
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 45945bfeee92..7879a5470773 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -3326,6 +3326,7 @@ static int sd_revalidate_disk(struct gendisk *disk)
  		sd_read_write_same(sdkp, buffer);
  		sd_read_security(sdkp, buffer);
  		sd_config_protection(sdkp);
+		sd_read_cdl(sdkp, buffer);
  	}
/*
@@ -3646,6 +3647,7 @@ static void scsi_disk_release(struct device *dev)
ida_free(&sd_index_ida, sdkp->index);
  	sd_zbc_free_zone_info(sdkp);
+	sd_cdl_release(sdkp);
  	put_device(&sdkp->device->sdev_gendev);
  	free_opal_dev(sdkp->opal_dev);
Hmm. Calling this during revalidate() makes sense, but how can we ensure that we call revalidate() when the user issues a MODE_SELECT command?

Other than that:

Reviewed-by: Hannes Reinecke <hare@xxxxxxx>

Cheers,

Hannes



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