linux.git/drivers/target/target_core_device.c, branch v5.15.134

scsi: target: Fix multiple LUN_RESET handling

2023-05-11T14:00:26+00:00

[ Upstream commit 673db054d7a2b5a470d7a25baf65956d005ad729 ]

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 
Signed-off-by: Sasha Levin

target: remove an incorrect unmap zeroes data deduction

2022-06-09T08:22:47+00:00

[ Upstream commit 179d8609d8424529e95021df939ed7b0b82b37f1 ]

For block devices, the SCSI target drivers implements UNMAP as calls to
blkdev_issue_discard, which does not guarantee zeroing just because
Write Zeroes is supported.

Note that this does not affect the file backed path which uses
fallocate to punch holes.

Fixes: 2237498f0b5c ("target/iblock: Convert WRITE_SAME to blkdev_issue_zeroout")
Signed-off-by: Christoph Hellwig 
Reviewed-by: Martin K. Petersen 
Reviewed-by: Chaitanya Kulkarni 
Link: https://lore.kernel.org/r/20220415045258.199825-2-hch@lst.de
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

scsi: target: Fix ordered tag handling

2021-11-25T08:48:29+00:00

[ Upstream commit ed1227e080990ffec5bf39006ec8a57358e6689a ]

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/20210930020422.92578-3-michael.christie@oracle.com
Signed-off-by: Mike Christie 
Signed-off-by: Martin K. Petersen 
Signed-off-by: Sasha Levin

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

2021-05-15T18:14:28+00:00

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/20210420185920.42431-3-s.samoylenko@yadro.com
Signed-off-by: Sergey Samoylenko 
Signed-off-by: Roman Bolshakov 
Signed-off-by: Martin K. Petersen

scsi: target: Make the virtual LUN 0 device

2021-04-06T03:26:39+00:00

Create the device for the virtual LUN 0 using the DUMMY flag. This change
makes it possible to remove some special-casing in the INQUIRY code.

Link: https://lore.kernel.org/r/20210322200938.53300-3-k.shelekhin@yadro.com
Reviewed-by: Roman Bolshakov 
Reviewed-by: Mike Christie 
Signed-off-by: Konstantin Shelekhin 
Signed-off-by: Martin K. Petersen

scsi: target: core: Add workqueue based cmd submission

2021-03-04T22:37:02+00:00

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/20210227170006.5077-17-michael.christie@oracle.com
Tested-by: Laurence Oberman 
Reviewed-by: Bodo Stroesser 
Signed-off-by: Mike Christie 
Signed-off-by: Martin K. Petersen

scsi: target: Make state_list per CPU

2020-11-05T03:39:38+00:00

Do a state_list/execute_task_lock per CPU, so we can do submissions from
different CPUs without contention with each other.

Note: tcm_fc was passing TARGET_SCF_USE_CPUID, but never set cpuid.  The
assumption is that it wanted to set the cpuid to the CPU it was submitting
from so it will get this behavior with this patch.

[mkp: s/printk/pr_err/ + resolve COMPARE AND WRITE patch conflict]

Link: https://lore.kernel.org/r/1604257174-4524-8-git-send-email-michael.christie@oracle.com
Reviewed-by: Himanshu Madhani 
Signed-off-by: Mike Christie 
Signed-off-by: Martin K. Petersen

scsi: target: Fix LUN ref count handling

2020-11-05T03:39:37+00:00

Fix two bugs in the LUN refcounting:

 1. For the TCM_WRITE_PROTECTED case we were returning an error after
    taking a ref to the LUN, but never dropping it (caller just send status
    and drops cmd ref).

 2. We still need to do a percpu_ref_tryget_live for the virt LUN 0 like we
    do for other LUNs, because the TPG code does the refcount/wait process
    like it does with other LUNs.

Link: https://lore.kernel.org/r/1604257174-4524-2-git-send-email-michael.christie@oracle.com
Reviewed-by: Himanshu Madhani 
Signed-off-by: Mike Christie 
Signed-off-by: Martin K. Petersen

scsi: target: Initialize LUN in transport_init_se_cmd()

2020-06-10T01:57:26+00:00

Initialization of orig_fe_lun is moved to transport_init_se_cmd() from
transport_lookup_cmd_lun(). This helps for the cases where the SCSI request
fails before the call to transport_lookup_cmd_lun() so that
trace_target_cmd_complete() can print the LUN information to the trace
buffer. Due to this change, the lun parameter is removed from
transport_lookup_cmd_lun() and transport_lookup_tmr_lun().

Link: https://lore.kernel.org/r/1591559913-8388-3-git-send-email-sudhakar.panneerselvam@oracle.com
Reviewed-by: Mike Christie 
Signed-off-by: Sudhakar Panneerselvam 
Signed-off-by: Martin K. Petersen

scsi: target: core: Add initiatorname to NON_EXISTENT_LUN error

2020-05-20T01:27:10+00:00

The NON_EXISTENT_LUN error can be written without an error condition
on the initiator responsible. Adding the initiatorname to this message
will reduce the effort required to fix this when many initiators are
supported by a target.

This version ensures the initiator name is also printed on the same message
in transport_lookup_tmr_lun for consistency.

Link: https://lore.kernel.org/r/9b13bb2e1f52f1792cd81850ee95bf3781bb5363.1589759816.git.lance.digby@gmail.com
Reviewed-by: Mike Christie 
Signed-off-by: Lance Digby 
Signed-off-by: Martin K. Petersen