linux-toradex.git/drivers/target/loopback, branch v6.7-rc8

scsi: target: Allow userspace to request direct submissions

2023-10-13T19:53:58+00:00

This allows userspace to request the fabric drivers do direct submissions
if they support it. With the new device file, submit_type, users can
write 0 - 2 to control how commands are submitted to the backend:

 0 - TARGET_FABRIC_DEFAULT_SUBMIT - LIO will use the fabric's default
     submission type. This is the default for compat.

 1 - TARGET_DIRECT_SUBMIT - LIO will submit the cmd to the backend from the
     calling context if the fabric the cmd was received on supports it,
     else it will use the fabric's default type.

 2 - TARGET_QUEUE_SUBMIT - LIO will queue the cmd to the LIO submission
     workqueue which will pass it to the backend.

When using an NVMe drive and vhost-scsi with direct submission we see
around a 20% improvement in 4K I/Os:

fio jobs        1       2       4       8       10
--------------------------------------------------
defer           94K     190K    394K    770K    890K
direct          128K    252K    488K    950K    -

And when using the queueing mode, we now no longer see issues like where
the iSCSI tx thread is blocked in the block layer waiting on a tag so it
can't respond to a nop or perform I/Os for other LUs.

Signed-off-by: Mike Christie 
Link: https://lore.kernel.org/r/20230928020907.5730-6-michael.christie@oracle.com
Signed-off-by: Martin K. Petersen

scsi: target: Have drivers report if they support direct submissions

2023-10-13T19:53:57+00:00

In some cases, like with multiple LUN targets or where the target has to
respond to transport level requests from the receiving context it can be
better to defer cmd submission to a helper thread. If the backend driver
blocks on something like request/tag allocation it can block the entire
target submission path and other LUs and transport IO on that session.

In other cases like single LUN targets with storage that can support all
the commands that the target can queue, then it's best to submit the cmd
to the backend from the target's cmd receiving context.

Subsequent commits will allow the user to config what they prefer, but
drivers like loop can't directly submit because they can be called from a
context that can't sleep. And, drivers like vhost-scsi can support direct
submission, but need to keep their default behavior of deferring execution
to avoid possible regressions where the backend can block.

Make the drivers tell LIO core if they support direct submissions and their
current default, so we can prevent users from misconfiguring the system and
initialize devices correctly.

Signed-off-by: Mike Christie 
Link: https://lore.kernel.org/r/20230928020907.5730-2-michael.christie@oracle.com
Signed-off-by: Martin K. Petersen

scsi: target: tcm_loop: Remove redundant driver match function

2023-03-25T00:44:14+00:00

If there is no driver match function, the driver core assumes that each
candidate pair (driver, device) matches. See driver_match_device().

pseudo_lld_bus_match() always returns 1 and is therefore equivalent to not
registering a match function. Remove it.

Signed-off-by: Lizhe 
Link: https://lore.kernel.org/r/20230319043518.297490-1-sensor1010@163.com
Signed-off-by: Martin K. Petersen

Merge patch series "Constify most SCSI host templates"

2023-03-25T00:13:03+00:00

Bart Van Assche  says:

It helps humans and the compiler if it is made explicit that SCSI host
templates are not modified. Hence this patch series that constifies most
SCSI host templates. Please consider this patch series for the next merge
window.

Link: https://lore.kernel.org/r/20230322195515.1267197-1-bvanassche@acm.org
Signed-off-by: Martin K. Petersen

scsi: target: tcm-loop: Declare SCSI host template const

2023-03-24T23:20:00+00:00

Make it explicit that the SCSI host template is not modified.

Signed-off-by: Bart Van Assche 
Link: https://lore.kernel.org/r/20230322195515.1267197-79-bvanassche@acm.org
Signed-off-by: Martin K. Petersen

scsi: target: loop: Remove default fabric ops callouts

2023-03-17T03:36:36+00:00

Remove callouts that are identical to the default implementations in TCM
Core.

Signed-off-by: Dmitry Bogdanov 
Link: https://lore.kernel.org/r/20230313181110.20566-5-d.bogdanov@yadro.com
Signed-off-by: Martin K. Petersen

scsi: target: tcm_loop: Fix possible name leak in tcm_loop_setup_hba_bus()

2022-11-17T17:46:16+00:00

If device_register() fails in tcm_loop_setup_hba_bus(), the name allocated
by dev_set_name() need be freed. As comment of device_register() says, it
should use put_device() to give up the reference in the error path. So fix
this by calling put_device(), then the name can be freed in kobject_cleanup().
The 'tl_hba' will be freed in tcm_loop_release_adapter(), so it don't need
goto error label in this case.

Fixes: 3703b2c5d041 ("[SCSI] tcm_loop: Add multi-fabric Linux/SCSI LLD fabric module")
Signed-off-by: Yang Yingliang 
Link: https://lore.kernel.org/r/20221115015042.3652261-1-yangyingliang@huawei.com
Reviewed-by: Mike Christie 
Signed-off-by: Martin K. Petersen

scsi: target: tcm_loop: Call scsi_done() directly

2021-10-17T01:31:43+00:00

Conditional statements are faster than indirect calls. Hence call
scsi_done() directly.

Link: https://lore.kernel.org/r/20211007204618.2196847-9-bvanassche@acm.org
Signed-off-by: Bart Van Assche 
Signed-off-by: Martin K. Petersen

Merge tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi

2021-09-02T22:09:46+00:00

Pull SCSI updates from James Bottomley:
 "This series consists of the usual driver updates (ufs, qla2xxx,
  target, smartpqi, lpfc, mpt3sas).

  The core change causing the most churn was replacing the command
  request field request with a macro, allowing us to offset map to it
  and remove the redundant field; the same was also done for the tag
  field.

  The most impactful change is the final removal of scsi_ioctl, which
  has been deprecated for over a decade"

* tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: (293 commits)
  scsi: ufs: Fix ufshcd_request_sense_async() for Samsung KLUFG8RHDA-B2D1
  scsi: ufs: ufs-exynos: Fix static checker warning
  scsi: mpt3sas: Use the proper SCSI midlayer interfaces for PI
  scsi: lpfc: Use the proper SCSI midlayer interfaces for PI
  scsi: lpfc: Copyright updates for 14.0.0.1 patches
  scsi: lpfc: Update lpfc version to 14.0.0.1
  scsi: lpfc: Add bsg support for retrieving adapter cmf data
  scsi: lpfc: Add cmf_info sysfs entry
  scsi: lpfc: Add debugfs support for cm framework buffers
  scsi: lpfc: Add support for maintaining the cm statistics buffer
  scsi: lpfc: Add rx monitoring statistics
  scsi: lpfc: Add support for the CM framework
  scsi: lpfc: Add cmfsync WQE support
  scsi: lpfc: Add support for cm enablement buffer
  scsi: lpfc: Add cm statistics buffer support
  scsi: lpfc: Add EDC ELS support
  scsi: lpfc: Expand FPIN and RDF receive logging
  scsi: lpfc: Add MIB feature enablement support
  scsi: lpfc: Add SET_HOST_DATA mbox cmd to pass date/time info to firmware
  scsi: fc: Add EDC ELS definition
  ...

scsi: tcm_loop: Use scsi_cmd_to_rq() instead of scsi_cmnd.request

2021-08-12T02:25:42+00:00

Prepare for removal of the request pointer by using scsi_cmd_to_rq()
instead. This patch does not change any functionality.

Link: https://lore.kernel.org/r/20210809230355.8186-51-bvanassche@acm.org
Signed-off-by: Bart Van Assche 
Signed-off-by: Martin K. Petersen