linux.git/drivers/target/target_core_device.c, branch v5.19

block: add a bdev_discard_granularity helper

2022-04-18T01:49:59+00:00

Abstract away implementation details from file systems by providing a
block_device based helper to retrieve the discard granularity.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Martin K. Petersen 
Acked-by: Christoph Böhmwalder  [drbd]
Acked-by: Ryusuke Konishi 
Acked-by: David Sterba  [btrfs]
Link: https://lore.kernel.org/r/20220415045258.199825-26-hch@lst.de
Signed-off-by: Jens Axboe

block: remove QUEUE_FLAG_DISCARD

2022-04-18T01:49:59+00:00

Just use a non-zero max_discard_sectors as an indicator for discard
support, similar to what is done for write zeroes.

The only places where needs special attention is the RAID5 driver,
which must clear discard support for security reasons by default,
even if the default stacking rules would allow for it.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Martin K. Petersen 
Acked-by: Christoph Böhmwalder  [drbd]
Acked-by: Jan Höppner  [s390]
Acked-by: Coly Li  [bcache]
Acked-by: David Sterba  [btrfs]
Reviewed-by: Chaitanya Kulkarni 
Link: https://lore.kernel.org/r/20220415045258.199825-25-hch@lst.de
Signed-off-by: Jens Axboe

block: add a bdev_max_discard_sectors helper

2022-04-18T01:49:59+00:00

Add a helper to query the number of sectors support per each discard bio
based on the block device and use this helper to stop various places from
poking into the request_queue to see if discard is supported and if so how
much.  This mirrors what is done e.g. for write zeroes as well.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Martin K. Petersen 
Acked-by: Christoph Böhmwalder  [drbd]
Acked-by: Coly Li  [bcache]
Acked-by: David Sterba  [btrfs]
Reviewed-by: Chaitanya Kulkarni 
Link: https://lore.kernel.org/r/20220415045258.199825-24-hch@lst.de
Signed-off-by: Jens Axboe

target: fix discard alignment on partitions

2022-04-18T01:49:58+00:00

Use the proper bdev_discard_alignment helper that accounts for partition
offsets.

Fixes: c66ac9db8d4a ("[SCSI] target: Add LIO target core v4.0.0-rc6")
Signed-off-by: Christoph Hellwig 
Reviewed-by: Martin K. Petersen 
Reviewed-by: Chaitanya Kulkarni 
Link: https://lore.kernel.org/r/20220415045258.199825-4-hch@lst.de
Signed-off-by: Jens Axboe

target: pass a block_device to target_configure_unmap_from_queue

2022-04-18T01:49:58+00:00

The SCSI target drivers is a consumer of the block layer and shoul
d generally work on struct block_device.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Martin K. Petersen 
Reviewed-by: Chaitanya Kulkarni 
Link: https://lore.kernel.org/r/20220415045258.199825-3-hch@lst.de
Signed-off-by: Jens Axboe

target: remove an incorrect unmap zeroes data deduction

2022-04-18T01:49:58+00:00

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

scsi: target: Fix ordered tag handling

2021-10-19T02:38:35+00:00

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

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