[PATCH RFC v2 00/18] blk-mq/libata/scsi: SCSI driver tagging improvements

John Garry
2022-06-09T10:36:03Z

Currently SCSI low-level drivers are required to manage tags for commands
which do not come via the block layer - libata internal commands would be
an example of one of these. We want to make blk-mq manage these tags also.

There was some work to provide "reserved commands" support in such series
as https://lore.kernel.org/linux-scsi/20211125151048.103910-1-hare@suse.de/

This was based on allocating a request for the lifetime of the "internal"
command.

This series tries to solve that problem by not just allocating the request
but also sending it as a request through the block layer. Reasons to do
this:
- Normal flow of a request and also commonality for regular scsi command
lifetime
- We don't leave request and scsi_cmnd fields dangling as when we just
allocate and free the request for the lifetime of the "internal" command
- For poll mode support we can only poll in block layer, so could not send
internal commands on poll mode queues if we did not do this, which is a
problem
- Can get rid of duplicated code like libsas internal command timeout
handling

Based on v5.19-rc1

Please consider as an PoC for now. I have broken builds, bisectablility,
and functionality for a lot of libsas drivers, like pm8001. Indeed,
10/18 onwards need a lot of work...

Testing:
QEMU with AHCI with disk and cdrom attached and hisi_sas v2 both boot.

v1 was sent here:
https://lore.kernel.org/linux-scsi/1647945585-197349-1-git-send-email-john.garry@huawei.com/

Hannes Reinecke (1):
scsi: core: Implement reserved command handling

John Garry (17):
blk-mq: Add a flag for reserved requests
scsi: core: Resurrect scsi_{get,free}_host_dev()
scsi: core: Add support to send reserved commands
scsi: core: Allocate SCSI host sdev when required
libata-scsi: Add ata_scsi_queue_internal()
libata-scsi: Add ata_internal_queuecommand()
libata: Queue ATA internal commands as requests
scsi: ipr: Support reserved commands
libata/scsi: libsas: Add sas_queuecommand_internal()
scsi: libsas: Don't attempt to find scsi host rphy in slave alloc
scsi: libsas drivers: Prepare for reserved commands
scsi: libsas: Allocate SCSI commands for tasks
scsi: libsas: Queue SMP commands as requests
scsi: libsas: Queue TMF commands as requests
scsi: core: Add scsi_alloc_request_hwq()
scsi: libsas: Queue internal abort commands as requests
scsi: libsas drivers: Remove private tag management

block/blk-mq.c | 6 +
drivers/ata/libata-core.c | 145 +++++++++++++++----------
drivers/ata/libata-sata.c | 5 +-
drivers/ata/libata-scsi.c | 61 ++++++++++-
drivers/ata/libata.h | 4 -
drivers/scsi/hisi_sas/hisi_sas_main.c | 93 ++++------------
drivers/scsi/hisi_sas/hisi_sas_v2_hw.c | 6 +-
drivers/scsi/hisi_sas/hisi_sas_v3_hw.c | 3 +-
drivers/scsi/hosts.c | 14 +++
drivers/scsi/ipr.c | 17 ++-
drivers/scsi/libsas/sas_ata.c | 22 ++--
drivers/scsi/libsas/sas_expander.c | 24 ++--
drivers/scsi/libsas/sas_init.c | 74 ++++++++-----
drivers/scsi/libsas/sas_internal.h | 6 +
drivers/scsi/libsas/sas_scsi_host.c | 121 +++++++++++++++------
drivers/scsi/scsi_lib.c | 50 ++++++++-
drivers/scsi/scsi_scan.c | 57 ++++++++++
include/linux/blk-mq.h | 6 +
include/linux/libata.h | 13 ++-
include/scsi/libsas.h | 57 +++++++++-
include/scsi/scsi_cmnd.h | 8 ++
include/scsi/scsi_host.h | 34 +++++-
22 files changed, 597 insertions(+), 229 deletions(-)

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2.26.2