kernel/linux.git/include/target/target_core_base.h, branch v6.18.21

scsi: target: Fix LUN/device R/W and total command stats

2025-12-18T13:02:48+00:00

[ Upstream commit 95aa2041c654161d1b5c1eca5379d67d91ef1cf2 ] In commit 9cf2317b795d ("scsi: target: Move I/O path stats to per CPU") I saw we sometimes use %u and also misread the spec. As a result I thought all the stats were supposed to be 32-bit only. However, for the majority of cases we support currently, the spec specifies u64 bit stats. This patch converts the stats changed in the commit above to u64. Fixes: 9cf2317b795d ("scsi: target: Move I/O path stats to per CPU") Signed-off-by: Mike Christie Reviewed-by: Dmitry Bogdanov Link: https://patch.msgid.link/20250917221338.14813-2-michael.christie@oracle.com Signed-off-by: Martin K. Petersen Signed-off-by: Sasha Levin

scsi: target: core: Constify enabled() in struct target_opcode_descriptor

2025-05-21T02:11:03+00:00

Constify the first argument of the enabled() function in struct target_opcode_descriptor. This is the first step in order to constify struct target_opcode_descriptor. Signed-off-by: Christophe JAILLET Link: https://lore.kernel.org/r/4290cf1dbe100c1b1edf2ede5e5aef19b04ee7f2.1747592774.git.christophe.jaillet@wanadoo.fr Signed-off-by: Martin K. Petersen

scsi: target: Move delayed/ordered tracking to per CPU

2025-04-29T01:47:55+00:00

The atomic use from the delayed/ordered tracking is causing perf issues when using higher perf backend devices and multiple queues. This moves the values to a per CPU counter. Combined with the per CPU stats patch, this improves IOPS by up to 33% for 8K IOS when using 4 or more queues from the initiator. Signed-off-by: Mike Christie Link: https://lore.kernel.org/r/20250424032741.16216-3-michael.christie@oracle.com Reviewed-by: Hannes Reinecke Signed-off-by: Martin K. Petersen

scsi: target: Move I/O path stats to per CPU

2025-04-29T01:47:55+00:00

The atomic use in the main I/O path is causing perf issues when using higher performance backend devices and multiple queues. This moves the stats to per CPU. Combined with the next patch that moves the non_ordered/delayed_cmd_count to per CPU, IOPS by up to 33% for 8K IOS when using 4 or more queues. Signed-off-by: Mike Christie Link: https://lore.kernel.org/r/20250424032741.16216-2-michael.christie@oracle.com Reviewed-by: Hannes Reinecke Signed-off-by: Martin K. Petersen

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

Merge patch series "Use block pr_ops in LIO"

2023-05-22T20:35:02+00:00

Mike Christie says: The patches in this thread allow us to use the block pr_ops with LIO's target_core_iblock module to support cluster applications in VMs. They were built over Linus's tree. They also apply over linux-next and Martin's tree and Jens's trees. Currently, to use windows clustering or linux clustering (pacemaker + cluster labs scsi fence agents) in VMs with LIO and vhost-scsi, you have to use tcmu or pscsi or use a cluster aware FS/framework for the LIO pr file. Setting up a cluster FS/framework is pain and waste when your real backend device is already a distributed device, and pscsi and tcmu are nice for specific use cases, but iblock gives you the best performance and allows you to use stacked devices like dm-multipath. So these patches allow iblock to work like pscsi/tcmu where they can pass a PR command to the backend module. And then iblock will use the pr_ops to pass the PR command to the real devices similar to what we do for unmap today. The patches are separated in the following groups: Patch 1 - 2: - Add block layer callouts for reading reservations and rename reservation error code. Patch 3 - 5: - SCSI support for new callouts. Patch 6: - DM support for new callouts. Patch 7 - 13: - NVMe support for new callouts. Patch 14 - 18: - LIO support for new callouts. This patchset has been tested with the libiscsi PGR ops and with window's failover cluster verification test. Note that for scsi backend devices we need this patchset: https://lore.kernel.org/linux-scsi/20230123221046.125483-1-michael.christie@oracle.com/T/#m4834a643ffb5bac2529d65d40906d3cfbdd9b1b7 to handle UAs. To reduce the size of this patchset that's being done separately to make reviewing easier. And to make merging easier this patchset and the one above do not have any conflicts so can be merged in different trees. Link: https://lore.kernel.org/r/20230407200551.12660-1-michael.christie@oracle.com Signed-off-by: Martin K. Petersen

scsi: target: Pass struct target_opcode_descriptor to enabled

2023-04-12T01:55:36+00:00

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 Link: https://lore.kernel.org/r/20230407200551.12660-17-michael.christie@oracle.com Reviewed-by: Christoph Hellwig Reviewed-by: Hannes Reinecke Signed-off-by: Martin K. Petersen

Merge patch series "target: TMF and recovery fixes"

2023-03-24T21:39:15+00:00

Mike Christie says: The following patches apply over Martin's 6.4 branches and Linus's tree. They fix a couple regressions in iscsit that occur when there are TMRs executing and a connection is closed. It also includes Dimitry's fixes in related code paths for cmd cleanup when ERL2 is used and the write pending hang during conn cleanup. This version of the patchset brings it back to just regressions and fixes for bugs we have a lot of users hitting. I'm going to fix isert and get it hooked into iscsit properly in a second patchset, because this one was getting so large. I've also moved my cleanup type of patches for a 3rd patchset. Link: https://lore.kernel.org/r/20230319015620.96006-1-michael.christie@oracle.com Signed-off-by: Martin K. Petersen

scsi: target: Fix multiple LUN_RESET handling

2023-03-24T21:32:23+00:00

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 Link: https://lore.kernel.org/r/20230319015620.96006-8-michael.christie@oracle.com Signed-off-by: Martin K. Petersen