scsi: target: Allow userspace to request direct submissions

This allows userspace to request the fabric drivers do direct submissions
if they support it. With the new device file, submit_type, users

scsi: target: Allow userspace to request direct submissions

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 <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Martin K. Petersen <[email protected]>

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

In some cases, like with multiple LUN targets or where the target has to
respond to transport level requests from the receiving c

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

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 <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Martin K. Petersen <[email protected]>

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scsi: target: Pass struct target_opcode_descriptor to enabled

The iblock pr_ops support does not support commands that require port or
I_T Nexus info. This adds a struct target_opcode_descriptor as

scsi: target: Pass struct target_opcode_descriptor to enabled

The iblock pr_ops support does not support commands that require port or
I_T Nexus info. This adds a struct target_opcode_descriptor as an argument
to the enabled callout so we can still have the common tcm_is_pr_enabled
and tcm_is_scsi2_reservations_enabled functions and also determine if the
command is supported based on the command and service action and device
settings.

Signed-off-by: Mike Christie <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Christoph Hellwig <[email protected]>
Reviewed-by: Hannes Reinecke <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

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scsi: target: Fix multiple LUN_RESET handling

This fixes a bug where an initiator thinks a LUN_RESET has cleaned up
running commands when it hasn't. The bug was added in commit 51ec502a3266
("target

scsi: target: Fix multiple LUN_RESET handling

This fixes a bug where an initiator thinks a LUN_RESET has cleaned up
running commands when it hasn't. The bug was added in commit 51ec502a3266
("target: Delete tmr from list before processing").

The problem occurs when:

1. We have N I/O cmds running in the target layer spread over 2 sessions.

2. The initiator sends a LUN_RESET for each session.

3. session1's LUN_RESET loops over all the running commands from both
sessions and moves them to its local drain_task_list.

4. session2's LUN_RESET does not see the LUN_RESET from session1 because
the commit above has it remove itself. session2 also does not see any
commands since the other reset moved them off the state lists.

5. sessions2's LUN_RESET will then complete with a successful response.

6. sessions2's inititor believes the running commands on its session are
now cleaned up due to the successful response and cleans up the running
commands from its side. It then restarts them.

7. The commands do eventually complete on the backend and the target
starts to return aborted task statuses for them. The initiator will
either throw a invalid ITT error or might accidentally lookup a new
task if the ITT has been reallocated already.

Fix the bug by reverting the patch, and serialize the execution of
LUN_RESETs and Preempt and Aborts.

Also prevent us from waiting on LUN_RESETs in core_tmr_drain_tmr_list,
because it turns out the original patch fixed a bug that was not
mentioned. For LUN_RESET1 core_tmr_drain_tmr_list can see a second
LUN_RESET and wait on it. Then the second reset will run
core_tmr_drain_tmr_list and see the first reset and wait on it resulting in
a deadlock.

Fixes: 51ec502a3266 ("target: Delete tmr from list before processing")
Signed-off-by: Mike Christie <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Martin K. Petersen <[email protected]>

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scsi: target: Move sess cmd counter to new struct

iSCSI needs to wait on outstanding commands like how SRP and the FC/FCoE
drivers do. It can't use target_stop_session() because for MCS support we
c

scsi: target: Move sess cmd counter to new struct

iSCSI needs to wait on outstanding commands like how SRP and the FC/FCoE
drivers do. It can't use target_stop_session() because for MCS support we
can't stop the entire session during recovery because if other connections
are OK then we want to be able to continue to execute I/O on them.

Move the per session cmd counters to a new struct so iSCSI can allocate
them per connection. The xcopy code can also just not allocate in the
future since it doesn't need to track commands.

Signed-off-by: Mike Christie <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Maurizio Lombardi <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

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scsi: target: core: Add RTPI attribute for target port

RELATIVE TARGET PORT IDENTIFIER can be read and configured via configfs:

$ echo 0x10 > $TARGET/tpgt_N/rtpi

RTPI can be changed only on disabl

scsi: target: core: Add RTPI attribute for target port

RELATIVE TARGET PORT IDENTIFIER can be read and configured via configfs:

$ echo 0x10 > $TARGET/tpgt_N/rtpi

RTPI can be changed only on disabled target ports.

Co-developed-by: Roman Bolshakov <[email protected]>
Signed-off-by: Roman Bolshakov <[email protected]>
Signed-off-by: Dmitry Bogdanov <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Mike Christie <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

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scsi: target: core: Drop device-based RTPI

The code is not needed since target port-based RTPI allocation replaced it.

Reviewed-by: Christoph Hellwig <[email protected]>
Signed-off-by: Roman Bolshakov <r.

scsi: target: core: Drop device-based RTPI

The code is not needed since target port-based RTPI allocation replaced it.

Reviewed-by: Christoph Hellwig <[email protected]>
Signed-off-by: Roman Bolshakov <[email protected]>
Signed-off-by: Dmitry Bogdanov <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Mike Christie <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

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scsi: target: core: Add RTPI field to target port

SAM-5 4.6.5.2 (Relative Port Identifier attribute) defines the attribute as
unique across SCSI target ports.

The change introduces RTPI attribute t

scsi: target: core: Add RTPI field to target port

SAM-5 4.6.5.2 (Relative Port Identifier attribute) defines the attribute as
unique across SCSI target ports.

The change introduces RTPI attribute to se_portal group. The value is
unique across all enabled SCSI target ports. It also limits number of SCSI
target ports to 65535.

Signed-off-by: Dmitry Bogdanov <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Mike Christie <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

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scsi: target: core: Send max transfer length in blocks

A MAXIMUM TRANSFER LENGTH value indicates the maximum transfer length in
logical blocks that the device server accepts for a single command. Fi

scsi: target: core: Send max transfer length in blocks

A MAXIMUM TRANSFER LENGTH value indicates the maximum transfer length in
logical blocks that the device server accepts for a single command. Fix
function sending the length in sectors instead of blocks.

This patch also removes the special casing for fileio in block_size_store
since this logic in now unified in spc_emulate_evpd_b0() for all backends.

Reviewed-by: Konstantin Shelekhin <[email protected]>
Reviewed-by: Dmitriy Bogdanov <[email protected]>
Signed-off-by: Anastasia Kovaleva <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Mike Christie <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

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scsi: target: core: Dynamically set DPO and FUA in usage_bits

libiscsi tests check the support of DPO & FUA bits in usage bits of RSOC
response. This patch adds support for dynamic usage bits for e

scsi: target: core: Dynamically set DPO and FUA in usage_bits

libiscsi tests check the support of DPO & FUA bits in usage bits of RSOC
response. This patch adds support for dynamic usage bits for each opcode.
Set support of DPO & FUA bits in usage_bits of RSOC response depending on
support DPOFUA in the backstore device.

Reviewed-by: Roman Bolshakov <[email protected]>
Reviewed-by: Konstantin Shelekhin <[email protected]>
Signed-off-by: Dmitry Bogdanov <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Mike Christie <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

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scsi: target: core: Add emulate_rsoc attribute

Allow support for RSOC to be turned off via the emulate_rsoc attibute.
This is just for testing purposes.

Reviewed-by: Roman Bolshakov <r.bolshakov@ya

scsi: target: core: Add emulate_rsoc attribute

Allow support for RSOC to be turned off via the emulate_rsoc attibute.
This is just for testing purposes.

Reviewed-by: Roman Bolshakov <[email protected]>
Signed-off-by: Dmitry Bogdanov <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Mike Christie <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

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scsi: target: core: Dynamic opcode support in RSOC

Report supported opcodes depending on a dynamic device configuration.

Reviewed-by: Roman Bolshakov <[email protected]>
Signed-off-by: Dmitry B

scsi: target: core: Dynamic opcode support in RSOC

Report supported opcodes depending on a dynamic device configuration.

Reviewed-by: Roman Bolshakov <[email protected]>
Signed-off-by: Dmitry Bogdanov <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Mike Christie <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

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scsi: target: core: Add support for RSOC command

Add support for REPORT SUPPORTED OPERATION CODES command according to SPC4.

Reviewed-by: Roman Bolshakov <[email protected]>
Signed-off-by: Dmit

scsi: target: core: Add support for RSOC command

Add support for REPORT SUPPORTED OPERATION CODES command according to SPC4.

Reviewed-by: Roman Bolshakov <[email protected]>
Signed-off-by: Dmitry Bogdanov <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Mike Christie <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

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scsi: target: core: De-RCU of se_lun and se_lun acl

se_lun and se_lun_acl are immutable pointers of struct se_dev_entry.
Remove RCU usage for access to those pointers.

Link: https://lore.kernel.org

scsi: target: core: De-RCU of se_lun and se_lun acl

se_lun and se_lun_acl are immutable pointers of struct se_dev_entry.
Remove RCU usage for access to those pointers.

Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Mike Christie <[email protected]>
Signed-off-by: Dmitry Bogdanov <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

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scsi: target: Replace lun_tg_pt_gp_lock with rcu in I/O path

We are only holding the lun_tg_pt_gp_lock in target_alua_state_check() to
make sure tg_pt_gp is not freed from under us while we copy the

scsi: target: Replace lun_tg_pt_gp_lock with rcu in I/O path

We are only holding the lun_tg_pt_gp_lock in target_alua_state_check() to
make sure tg_pt_gp is not freed from under us while we copy the state,
delay, ID values. We can instead use RCU here to access the tg_pt_gp.

With this patch IOPs can increase up to 10% for jobs like:

fio --filename=/dev/sdX --direct=1 --rw=randrw --bs=4k \
--ioengine=libaio --iodepth=64 --numjobs=N

when there are multiple sessions (running that fio command to each /dev/sdX
or using multipath and there are over 8 paths), or more than 8 queues for
the loop or vhost with multiple threads case and numjobs > 8.

Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Mike Christie <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

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scsi: target: Fix ordered tag handling

This patch fixes the following bugs:

1. If there are multiple ordered cmds queued and multiple simple cmds
completing, target_restart_delayed_cmds() could

scsi: target: Fix ordered tag handling

This patch fixes the following bugs:

1. If there are multiple ordered cmds queued and multiple simple cmds
completing, target_restart_delayed_cmds() could be called on different
CPUs and each instance could start a ordered cmd. They could then run in
different orders than they were queued.

2. target_restart_delayed_cmds() and target_handle_task_attr() can race
where:

1. target_handle_task_attr() has passed the simple_cmds == 0 check.

2. transport_complete_task_attr() then decrements simple_cmds to 0.

3. transport_complete_task_attr() runs target_restart_delayed_cmds() and
it does not see any cmds on the delayed_cmd_list.

4. target_handle_task_attr() adds the cmd to the delayed_cmd_list.

The cmd will then end up timing out.

3. If we are sent > 1 ordered cmds and simple_cmds == 0, we can execute
them out of order, because target_handle_task_attr() will hit that
simple_cmds check first and return false for all ordered cmds sent.

4. We run target_restart_delayed_cmds() after every cmd completion, so if
there is more than 1 simple cmd running, we start executing ordered cmds
after that first cmd instead of waiting for all of them to complete.

5. Ordered cmds are not supposed to start until HEAD OF QUEUE and all older
cmds have completed, and not just simple.

6. It's not a bug but it doesn't make sense to take the delayed_cmd_lock
for every cmd completion when ordered cmds are almost never used. Just
replacing that lock with an atomic increases IOPs by up to 10% when
completions are spread over multiple CPUs and there are multiple
sessions/ mqs/thread accessing the same device.

This patch moves the queued delayed handling to a per device work to
serialze the cmd executions for each device and adds a new counter to track
HEAD_OF_QUEUE and SIMPLE cmds. We can then check the new counter to
determine when to run the work on the completion path.

Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Mike Christie <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

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scsi: target: core: Add common tpg/enable attribute

Many fabric modules provide their own implementation of enable attribute in
tpg.

Provide a way to remove code duplication in the fabric modules a

scsi: target: core: Add common tpg/enable attribute

Many fabric modules provide their own implementation of enable attribute in
tpg.

Provide a way to remove code duplication in the fabric modules and
automatically add "enable" attribute if a fabric module has an
implementation of fabric_enable_tpg().

Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Roman Bolshakov <[email protected]>
Reviewed-by: Mike Christie <[email protected]>
Signed-off-by: Dmitry Bogdanov <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

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scsi: target: Allows backend drivers to fail with specific sense codes

Currently, backend drivers can fail I/O with SAM_STAT_CHECK_CONDITION which
gets us TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE.

Ad

scsi: target: Allows backend drivers to fail with specific sense codes

Currently, backend drivers can fail I/O with SAM_STAT_CHECK_CONDITION which
gets us TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE.

Add a new helper that allows backend drivers to fail with specific sense
codes.

This is based on a patch from Mike Christie <[email protected]>.

Cc: Mike Christie <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: David Disseldorp <[email protected]>
Signed-off-by: Sergey Samoylenko <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

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scsi: target: core: Drop unnecessary se_cmd ASC/ASCQ members

These members are only used for ALUA sense detail propagation, which can
just as easily be done via sense_reason_t.

Link: https://lore.k

scsi: target: core: Drop unnecessary se_cmd ASC/ASCQ members

These members are only used for ALUA sense detail propagation, which can
just as easily be done via sense_reason_t.

Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Mike Christie <[email protected]>
Signed-off-by: David Disseldorp <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

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scsi: target: core: Add configurable IEEE Company ID attribute

Implement an attribute which provides a way to set a company specific WWN
in configfs via:

target/core/$backstore/$name/wwn/company_

scsi: target: core: Add configurable IEEE Company ID attribute

Implement an attribute which provides a way to set a company specific WWN
in configfs via:

target/core/$backstore/$name/wwn/company_id

The Open Fabrics Alliance ID 001405h remains the default.

Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Sergey Samoylenko <[email protected]>
Signed-off-by: Roman Bolshakov <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

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scsi: target: core: Make completion affinity configurable

It may not always be best to complete the IO on same CPU as it was
submitted on. This commit allows userspace to configure it.

This has bee

scsi: target: core: Make completion affinity configurable

It may not always be best to complete the IO on same CPU as it was
submitted on. This commit allows userspace to configure it.

This has been useful for vhost-scsi where we have a single thread for
submissions and completions. If we force the completion on the submission
CPU we may be adding conflicts with what the user has setup in the lower
levels with settings like the block layer rq_affinity or the driver's IRQ
or softirq (the network's rps_cpus value) settings.

We may also want to set it up where the vhost thread runs on CPU N and does
its submissions/completions there, and then have LIO do its completion
booking on CPU M, but can't configure the lower levels due to issues like
using dm-multipath with lots of paths (the path selector can throw commands
all over the system because it's only taking into account latency/throughput
at its level).

The new setting is in:

/sys/kernel/config/target/$fabric/$target/param/cmd_completion_affinity

Writing:

-1 -> Gives the current default behavior of completing on the
submission CPU.

-2 -> Completes the cmd on the CPU the lower layers sent it to us from.

> 0 -> Completes on the CPU userspace has specified.

Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Himanshu Madhani <[email protected]>
Signed-off-by: Mike Christie <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

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scsi: target: core: Fix backend plugging

target_core_iblock is plugging and unplugging on every command and this is
causing perf issues for drivers that prefer batched cmds. With recent
patches we c

scsi: target: core: Fix backend plugging

target_core_iblock is plugging and unplugging on every command and this is
causing perf issues for drivers that prefer batched cmds. With recent
patches we can now take multiple cmds from a fabric driver queue and then
pass them down the backend drivers in a batch. This patch adds this support
by adding 2 callouts to the backend for plugging and unplugging the
device. Subsequent commits will add support for iblock and tcmu device
plugging.

Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Bodo Stroesser <[email protected]>
Signed-off-by: Mike Christie <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

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scsi: target: core: Cleanup cmd flag bits

We have a couple holes in the cmd flags definitions. This cleans up the
definitions to fix that and make it easier to read.

Link: https://lore.kernel.org/r

scsi: target: core: Cleanup cmd flag bits

We have a couple holes in the cmd flags definitions. This cleans up the
definitions to fix that and make it easier to read.

Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Chaitanya Kulkarni <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Reviewed-by: Himanshu Madhani <[email protected]>
Signed-off-by: Mike Christie <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

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scsi: target: core: Add workqueue based cmd submission

loop and vhost/scsi do their target cmd submission from driver
workqueues. This allows them to avoid an issue where the backend may block
waiti

scsi: target: core: Add workqueue based cmd submission

loop and vhost/scsi do their target cmd submission from driver
workqueues. This allows them to avoid an issue where the backend may block
waiting for resources like tags/requests, mem/locks, etc and that ends up
blocking their entire submission path and for the case of vhost-scsi both
the submission and completion path.

This patch adds a helper drivers can use to submit from a LIO workqueue.
This code will then be extended in the next patches to fix the plugging of
backend devices.

We are only converting vhost/loop initially, but the workqueue based
submission will work for other drivers and have similar benefits where the
main target loops will not end up blocking one some backend resource.

Link: https://lore.kernel.org/r/[email protected]
Tested-by: Laurence Oberman <[email protected]>
Reviewed-by: Bodo Stroesser <[email protected]>
Signed-off-by: Mike Christie <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

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scsi: target: core: Change ASCQ for residual write

According to FCP-4 (9.4.2):

If the command requested that data beyond the length specified by the
FCP_DL field be transferred, then the device

scsi: target: core: Change ASCQ for residual write

According to FCP-4 (9.4.2):

If the command requested that data beyond the length specified by the
FCP_DL field be transferred, then the device server shall set the
FCP_RESID_OVER bit (see 9.5.8) to one in the FCP_RSP IU and:

a) process the command normally except that data beyond the FCP_DL count
shall not be requested or transferred;

b) transfer no data and return CHECK CONDITION status with the sense key
set to ILLEGAL REQUEST and the additional sense code set to INVALID FIELD
IN COMMAND INFORMATION UNIT; or

c) may transfer data and return CHECK CONDITION status with the sense key
set to ABORTED COMMAND and the additional sense code set to INVALID FIELD
IN COMMAND INFORMATION UNIT.

TCM follows b) and transfers no data for residual writes but returns
INVALID FIELD IN CDB instead of INVALID FIELD IN COMMAND INFORMATION UNIT.

Change the ASCQ to INVALID FIELD IN COMMAND INFORMATION UNIT to meet the
standard.

Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Anastasia Kovaleva <[email protected]>
Signed-off-by: Roman Bolshakov <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

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