The current BSG design tries to shoe-horn the transport-specific
passthrough commands into the overall framework for SCSI passthrough
requests.  This has a couple problems:

 - each passthrough queue has to set the QUEUE_FLAG_SCSI_PASSTHROUGH flag
   despite not dealing with SCSI commands at all.  Because of that these
   queues could also incorrectly accept SCSI commands from in-kernel
   users or through the legacy SCSI_IOCTL_SEND_COMMAND ioctl.
 - the real SCSI bsg queues also incorrectly accept bsg requests of the
   BSG_SUB_PROTOCOL_SCSI_TRANSPORT type
 - the bsg transport code is almost unredable because it tries to reuse
   different SCSI concepts for its own purpose.

This patch instead adds a new bsg_ops structure to handle the two cases
differently, and thus solves all of the above problems.  Another side
effect is that the bsg-lib queues also don't need to embedd a
struct scsi_request anymore.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

The SCSI PRE-FETCH (10 or 16) command is present both on hard disks
and some SSDs. It is useful when the address of the next block(s) to
be read is known but it is not following the LBA of the current READ
(so read-ahead won't help). It returns two "good" SCSI Status values.
If the requested blocks have fitted (or will most likely fit (when
the IMMED bit is set)) into the disk's cache, it returns CONDITION
MET. If it didn't (or will not) fit then it returns GOOD status.

The goal of this patch is to stop the SCSI subsystem treating the
CONDITION MET SCSI status as an error. The current state makes the
PRE-FETCH command effectively unusable via pass-throughs.
Signed-off-by: NDouglas Gilbert <dgilbert@interlog.com>
Reviewed-by: NBart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

This patch has been generated as follows:

for verb in set_unlocked clear_unlocked set clear; do
  replace-in-files queue_flag_${verb} blk_queue_flag_${verb%_unlocked} \
    $(git grep -lw queue_flag_${verb} drivers block/bsg*)
done

Except for protecting all queue flag changes with the queue lock
this patch does not change any functionality.

Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Shaohua Li <shli@fb.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: NBart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: NMartin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Acked-by: NMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

In scsi core, __scsi_queue_insert should just put request back on the
queue and retry using the same command as before. However, for blk-mq,
scsi_mq_requeue_cmd is employed here which will unprepare the
request. To align with the semantics of __scsi_queue_insert, use
blk_mq_requeue_request with kick_requeue_list == true and put the
reference of scsi_device.

Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: NJianchao Wang <jianchao.w.wang@oracle.com>
Reviewed-by: NBart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

When converting __scsi_error_from_host_byte() to BLK_STS error codes the
case DID_OK was forgotten, resulting in it always returning an error.

Fixes: 2a842aca ("block: introduce new block status code type")
Cc: Doug Gilbert <dgilbert@interlog.com>
Signed-off-by: NHannes Reinecke <hare@suse.com>
Reviewed-by: NDouglas Gilbert <dgilbert@interlog.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Avoid that the recently introduced call_rcu() call in the SCSI core
triggers a double call_rcu() call.
Reported-by: NNatanael Copa <ncopa@alpinelinux.org>
Reported-by: NDamien Le Moal <damien.lemoal@wdc.com>
References: https://bugzilla.kernel.org/show_bug.cgi?id=198861
Fixes: 3bd6f43f ("scsi: core: Ensure that the SCSI error handler gets woken up")
Signed-off-by: NBart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: NDamien Le Moal <damien.lemoal@wdc.com>
Tested-by: NDamien Le Moal <damien.lemoal@wdc.com>
Cc: Natanael Copa <ncopa@alpinelinux.org>
Cc: Damien Le Moal <damien.lemoal@wdc.com>
Cc: Alexandre Oliva <oliva@gnu.org>
Cc: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

This patch does not change any functionality.
Signed-off-by: NBart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Philipp Reisner <philipp.reisner@linbit.com>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Make scsi_test_unit_ready() send at most as many TURs as specified in
the 'retries' argument instead of retries * (retries + 1) / 2.
Signed-off-by: NBart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

This status is returned from driver to block layer if device related
resource is unavailable, but driver can guarantee that IO dispatch
will be triggered in future when the resource is available.

Convert some drivers to return BLK_STS_DEV_RESOURCE.  Also, if driver
returns BLK_STS_RESOURCE and SCHED_RESTART is set, rerun queue after
a delay (BLK_MQ_DELAY_QUEUE) to avoid IO stalls.  BLK_MQ_DELAY_QUEUE is
3 ms because both scsi-mq and nvmefc are using that magic value.

If a driver can make sure there is in-flight IO, it is safe to return
BLK_STS_DEV_RESOURCE because:

1) If all in-flight IOs complete before examining SCHED_RESTART in
blk_mq_dispatch_rq_list(), SCHED_RESTART must be cleared, so queue
is run immediately in this case by blk_mq_dispatch_rq_list();

2) if there is any in-flight IO after/when examining SCHED_RESTART
in blk_mq_dispatch_rq_list():
- if SCHED_RESTART isn't set, queue is run immediately as handled in 1)
- otherwise, this request will be dispatched after any in-flight IO is
  completed via blk_mq_sched_restart()

3) if SCHED_RESTART is set concurently in context because of
BLK_STS_RESOURCE, blk_mq_delay_run_hw_queue() will cover the above two
cases and make sure IO hang can be avoided.

One invariant is that queue will be rerun if SCHED_RESTART is set.
Suggested-by: NJens Axboe <axboe@kernel.dk>
Tested-by: NLaurence Oberman <loberman@redhat.com>
Signed-off-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

SCSI sense buffers, stored in struct scsi_cmnd.sense and therefore
contained in the scsi_sense_cache slab cache, need to be copied to/from
userspace.

cache object allocation:
    drivers/scsi/scsi_lib.c:
        scsi_select_sense_cache(...):
            return ... ? scsi_sense_isadma_cache : scsi_sense_cache

        scsi_alloc_sense_buffer(...):
            return kmem_cache_alloc_node(scsi_select_sense_cache(), ...);

        scsi_init_request(...):
            ...
            cmd->sense_buffer = scsi_alloc_sense_buffer(...);
            ...
            cmd->req.sense = cmd->sense_buffer

example usage trace:

    block/scsi_ioctl.c:
        (inline from sg_io)
        blk_complete_sghdr_rq(...):
            struct scsi_request *req = scsi_req(rq);
            ...
            copy_to_user(..., req->sense, len)

        scsi_cmd_ioctl(...):
            sg_io(...);

In support of usercopy hardening, this patch defines a region in
the scsi_sense_cache slab cache in which userspace copy operations
are allowed.

This region is known as the slab cache's usercopy region. Slab caches
can now check that each dynamically sized copy operation involving
cache-managed memory falls entirely within the slab's usercopy region.
Signed-off-by: NDavid Windsor <dave@nullcore.net>
[kees: adjust commit log, provide usage trace]
Cc: "James E.J. Bottomley" <jejb@linux.vnet.ibm.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: linux-scsi@vger.kernel.org
Signed-off-by: NKees Cook <keescook@chromium.org>

This patch does not change any functionality but makes the SCSI core
source code slightly easier to read.
Signed-off-by: NBart Van Assche <bart.vanassche@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Commit 651a0136 ("scsi: scsi_transport_sas: switch to bsg-lib for
SMP passthrough") removed the only call to scsi_initialize_rq() from
outside the SCSI core. Hence unexport scsi_initialize_rq().
Signed-off-by: NBart Van Assche <bart.vanassche@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

If scsi_eh_scmd_add() is called concurrently with
scsi_host_queue_ready() while shost->host_blocked > 0 then it can
happen that neither function wakes up the SCSI error handler. Fix
this by making every function that decreases the host_busy counter
wake up the error handler if necessary and by protecting the
host_failed checks with the SCSI host lock.
Reported-by: NPavel Tikhomirov <ptikhomirov@virtuozzo.com>
References: https://marc.info/?l=linux-kernel&m=150461610630736
Fixes: commit 74665016 ("scsi: convert host_busy to atomic_t")
Signed-off-by: NBart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: NPavel Tikhomirov <ptikhomirov@virtuozzo.com>
Tested-by: NStuart Hayes <stuart.w.hayes@gmail.com>
Cc: Konstantin Khorenko <khorenko@virtuozzo.com>
Cc: Stuart Hayes <stuart.w.hayes@gmail.com>
Cc: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Before commit 0df21c86 ("scsi: implement .get_budget and .put_budget
for blk-mq"), we run queue after 3ms if queue is idle and SCSI device
queue isn't ready, which is done in handling BLK_STS_RESOURCE. After
commit 0df21c86 is introduced, queue won't be run any more under
this situation.

IO hang is observed when timeout happened, and this patch fixes the IO
hang issue by running queue after delay in scsi_dev_queue_ready, just
like non-mq. This issue can be triggered by the following script[1].

There is another issue which can be covered by running idle queue: when
.get_budget() is called on request coming from hctx->dispatch_list, if
one request just completes during .get_budget(), we can't depend on
SCSI's restart to make progress any more. This patch fixes the race too.

With this patch, we basically recover to previous behaviour (before
commit 0df21c86) of handling idle queue when running out of
resource.

[1] script for test/verify SCSI timeout
rmmod scsi_debug
modprobe scsi_debug max_queue=1

DEVICE=`ls -d /sys/bus/pseudo/drivers/scsi_debug/adapter*/host*/target*/*/block/* | head -1 | xargs basename`
DISK_DIR=`ls -d /sys/block/$DEVICE/device/scsi_disk/*`

echo "using scsi device $DEVICE"
echo "-1" >/sys/bus/pseudo/drivers/scsi_debug/every_nth
echo "temporary write through" >$DISK_DIR/cache_type
echo "128" >/sys/bus/pseudo/drivers/scsi_debug/opts
echo none > /sys/block/$DEVICE/queue/scheduler
dd if=/dev/$DEVICE of=/dev/null bs=1M iflag=direct count=1 &
sleep 5
echo "0" >/sys/bus/pseudo/drivers/scsi_debug/opts
wait
echo "SUCCESS"

Fixes: 0df21c86 ("scsi: implement .get_budget and .put_budget for blk-mq")
Signed-off-by: NMing Lei <ming.lei@redhat.com>
Tested-by: NHolger Hoffstätte <holger@applied-asynchrony.com>
Reviewed-by: NBart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

In non-coherent DMA mode, kernel uses cache flushing operations to
maintain I/O coherency, so scsi's block queue should be aligned to the
value returned by dma_get_cache_alignment().  Otherwise, If a DMA buffer
and a kernel structure share a same cache line, and if the kernel
structure has dirty data, cache_invalidate (no writeback) will cause
data corruption.

Cc: stable@vger.kernel.org
Signed-off-by: NHuacai Chen <chenhc@lemote.com>
[hch: rebased and updated the comment and changelog]
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The contexts from which a SCSI device can be quiesced or resumed are:
* Writing into /sys/class/scsi_device/*/device/state.
* SCSI parallel (SPI) domain validation.
* The SCSI device power management methods. See also scsi_bus_pm_ops.

It is essential during suspend and resume that neither the filesystem
state nor the filesystem metadata in RAM changes. This is why while
the hibernation image is being written or restored that SCSI devices
are quiesced. The SCSI core quiesces devices through scsi_device_quiesce()
and scsi_device_resume(). In the SDEV_QUIESCE state execution of
non-preempt requests is deferred. This is realized by returning
BLKPREP_DEFER from inside scsi_prep_state_check() for quiesced SCSI
devices. Avoid that a full queue prevents power management requests
to be submitted by deferring allocation of non-preempt requests for
devices in the quiesced state. This patch has been tested by running
the following commands and by verifying that after each resume the
fio job was still running:

for ((i=0; i<10; i++)); do
  (
    cd /sys/block/md0/md &&
    while true; do
      [ "$(<sync_action)" = "idle" ] && echo check > sync_action
      sleep 1
    done
  ) &
  pids=($!)
  for d in /sys/class/block/sd*[a-z]; do
    bdev=${d#/sys/class/block/}
    hcil=$(readlink "$d/device")
    hcil=${hcil#../../../}
    echo 4 > "$d/queue/nr_requests"
    echo 1 > "/sys/class/scsi_device/$hcil/device/queue_depth"
    fio --name="$bdev" --filename="/dev/$bdev" --buffered=0 --bs=512 \
      --rw=randread --ioengine=libaio --numjobs=4 --iodepth=16       \
      --iodepth_batch=1 --thread --loops=$((2**31)) &
    pids+=($!)
  done
  sleep 1
  echo "$(date) Hibernating ..." >>hibernate-test-log.txt
  systemctl hibernate
  sleep 10
  kill "${pids[@]}"
  echo idle > /sys/block/md0/md/sync_action
  wait
  echo "$(date) Done." >>hibernate-test-log.txt
done
Reported-by: NOleksandr Natalenko <oleksandr@natalenko.name>
References: "I/O hangs after resuming from suspend-to-ram" (https://marc.info/?l=linux-block&m=150340235201348).
Signed-off-by: NBart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NMartin Steigerwald <martin@lichtvoll.de>
Tested-by: NOleksandr Natalenko <oleksandr@natalenko.name>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Convert blk_get_request(q, op, __GFP_RECLAIM) into
blk_get_request_flags(q, op, BLK_MQ_PREEMPT). This patch does not
change any functionality.
Signed-off-by: NBart Van Assche <bart.vanassche@wdc.com>
Tested-by: NMartin Steigerwald <martin@lichtvoll.de>
Acked-by: David S. Miller <davem@davemloft.net> [ for IDE ]
Acked-by: NMartin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Tested-by: NOleksandr Natalenko <oleksandr@natalenko.name>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This reverts commit 8a97712e.

This commit added a call to sysfs_notify() from within
scsi_device_set_state(), which in turn turns out to make libata very
unhappy, because ata_eh_detach_dev() does

        spin_lock_irqsave(ap->lock, flags);
        ..
        if (ata_scsi_offline_dev(dev)) {
                dev->flags |= ATA_DFLAG_DETACHED;
                ap->pflags |= ATA_PFLAG_SCSI_HOTPLUG;
        }

and ata_scsi_offline_dev() then does that scsi_device_set_state() to set
it offline.

So now we called sysfs_notify() from within a spinlocked region, which
really doesn't work.  The 0day robot reported this as:

   BUG: sleeping function called from invalid context at kernel/locking/mutex.c:238

because sysfs_notify() ends up calling kernfs_find_and_get_ns() which
then does mutex_lock(&kernfs_mutex)..

The pollability of the device state isn't critical, so revert this all
for now, and maybe we'll do it differently in the future.
Reported-by: NFengguang Wu <fengguang.wu@intel.com>
Acked-by: NTejun Heo <tj@kernel.org>
Acked-by: NMartin K. Petersen <martin.petersen@oracle.com>
Acked-by: NHannes Reinecke <hare@suse.de>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

It is enough to just check if we can get the budget via .get_budget().
And we don't need to deal with device state change in .get_budget().

For SCSI, one issue to be fixed is that we have to call
scsi_mq_uninit_cmd() to free allocated ressources if SCSI device fails
to handle the request. And it isn't enough to simply call
blk_mq_end_request() to do that if this request is marked as
RQF_DONTPREP.

Fixes: 0df21c86(scsi: implement .get_budget and .put_budget for blk-mq)
Signed-off-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

It is very expensive to atomic_inc/atomic_dec the host wide counter of
host->busy_count, and it should have been avoided via blk-mq's mechanism
of getting driver tag, which uses the more efficient way of sbitmap queue.

Also we don't check atomic_read(&sdev->device_busy) in scsi_mq_get_budget()
and don't run queue if the counter becomes zero, so IO hang may be caused
if all requests are completed just before the current SCSI device
is added to shost->starved_list.

Fixes: 0df21c86(scsi: implement .get_budget and .put_budget for blk-mq)
Reported-by: NBart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We need to tell blk-mq to reserve resources before queuing one request,
so implement these two callbacks. Then blk-mq can avoid to dequeue
request too early, and IO merging can be improved a lot.
Signed-off-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

In the following patch, we will implement scsi_get_budget()
which need to call scsi_prep_state_check() when rq isn't
dequeued yet.
Signed-off-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

The legacy block layer handles requests as follows:
- If the prep function returns BLKPREP_OK, let blk_peek_request()
  return the pointer to that request.
- If the prep function returns BLKPREP_DEFER, keep the RQF_STARTED
  flag and retry calling the prep function later.
- If the prep function returns BLKPREP_KILL or BLKPREP_INVALID, end
  the request.

In none of these cases it is correct to clear the SCMD_INITIALIZED
flag from inside scsi_prep_fn(). Since scsi_prep_fn() already
guarantees that scsi_init_command() will be called once even if
scsi_prep_fn() is called multiple times, remove the code that clears
SCMD_INITIALIZED from scsi_prep_fn().

The scsi-mq code handles requests as follows:
- If scsi_mq_prep_fn() returns BLKPREP_OK, set the RQF_DONTPREP flag
  and submit the request to the SCSI LLD.
- If scsi_mq_prep_fn() returns BLKPREP_DEFER, call
  blk_mq_delay_run_hw_queue() and return BLK_STS_RESOURCE.
- If the prep function returns BLKPREP_KILL or BLKPREP_INVALID, call
  scsi_mq_uninit_cmd() and let the blk-mq core end the request.

In none of these cases scsi_mq_prep_fn() should clear the
SCMD_INITIALIZED flag. Hence remove the code from scsi_mq_prep_fn()
function that clears that flag.

This patch avoids that the following warning is triggered when using
the legacy block layer:

------------[ cut here ]------------
WARNING: CPU: 1 PID: 4198 at drivers/scsi/scsi_lib.c:654 scsi_end_request+0x1de/0x220
CPU: 1 PID: 4198 Comm: mkfs.f2fs Not tainted 4.14.0-rc5+ #1
task: ffff91c147a4b800 task.stack: ffffb282c37b8000
RIP: 0010:scsi_end_request+0x1de/0x220
Call Trace:
<IRQ>
scsi_io_completion+0x204/0x5e0
scsi_finish_command+0xce/0xe0
scsi_softirq_done+0x126/0x130
blk_done_softirq+0x6e/0x80
__do_softirq+0xcf/0x2a8
irq_exit+0xab/0xb0
do_IRQ+0x7b/0xc0
common_interrupt+0x90/0x90
</IRQ>
RIP: 0010:_raw_spin_unlock_irqrestore+0x9/0x10
__test_set_page_writeback+0xc7/0x2c0
__block_write_full_page+0x158/0x3b0
block_write_full_page+0xc4/0xd0
blkdev_writepage+0x13/0x20
__writepage+0x12/0x40
write_cache_pages+0x204/0x500
generic_writepages+0x48/0x70
blkdev_writepages+0x9/0x10
do_writepages+0x34/0xc0
__filemap_fdatawrite_range+0x6c/0x90
file_write_and_wait_range+0x31/0x90
blkdev_fsync+0x16/0x40
vfs_fsync_range+0x44/0xa0
do_fsync+0x38/0x60
SyS_fsync+0xb/0x10
entry_SYSCALL_64_fastpath+0x13/0x94
---[ end trace 86e8ef85a4a6c1d1 ]---

Fixes: commit 64104f70 ("scsi: Call scsi_initialize_rq() for filesystem requests")
Signed-off-by: NBart Van Assche <bart.vanassche@wdc.com>
Cc: Damien Le Moal <damien.lemoal@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: NDamien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

As per SAM there is a status precedence, with any sense code 29/XX
taking second place just after an ACA ACTIVE status.  Additionally, each
target might prefer to not queue any unit attention conditions, but just
report one.  Due to the above, this will be that one with the highest
precedence.  This results in the sense code 29/XX effectively
overwriting any other unit attention.  Hence we should report the
power-on reset to userland so that it can take appropriate action.
Signed-off-by: NHannes Reinecke <hare@suse.de>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Fix comments style (use kernel-doc style) and content to clarify some
functions. Also fix some functions signature indentation and remove a
useless blank line in sd_zbc_read_zones().

No functional change is introduced by this patch.
Signed-off-by: NDamien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

One of the two scsi-mq functions that requeue a request unprepares a
request before requeueing (scsi_io_completion()) but the other function
not (__scsi_queue_insert()). Make sure that a request is unprepared
before requeuing it.

Fixes: commit d285203c ("scsi: add support for a blk-mq based I/O path.")
Signed-off-by: NBart Van Assche <bart.vanassche@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Damien Le Moal <damien.lemoal@wdc.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Requests are unprepared and reprepared when being requeued.  Avoid that
requeuing resets .jiffies_at_alloc and .retries by initializing these
two member variables from inside scsi_initialize_rq() and by preserving
both member variables when preparing a request. This patch affects the
requeuing behavior of both the legacy scsi and the scsi-mq code paths.
Reported-by: NBrian King <brking@linux.vnet.ibm.com>
References: https://lkml.org/lkml/2017/8/18/923 ("Re: [BUG][bisected 270065e] linux-next fails to boot on powerpc")
Signed-off-by: NBart Van Assche <bart.vanassche@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Brian King <brking@linux.vnet.ibm.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

If a pass-through request is submitted then blk_get_request()
initializes that request by calling scsi_initialize_rq(). Also call this
function for filesystem requests. Introduce CMD_INITIALIZED to keep
track of whether or not a request has already been initialized.
Signed-off-by: NBart Van Assche <bart.vanassche@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Brian King <brking@linux.vnet.ibm.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Introduce struct scsi_vpd for the VPD page length, data and the RCU head
that will be used to free the VPD data. Use kfree_rcu() instead of
kfree() to free VPD data. Move the VPD buffer pointer check inside the
RCU read lock in the sysfs code. Only annotate pointers that are shared
across threads with __rcu. Use rcu_dereference() when dereferencing an
RCU pointer. This patch suppresses about twenty sparse complaints about
the vpd_pg8[03] pointers. This patch also fixes a race condition, namely
that updating of the VPD pointers and length variables in struct
scsi_device was not atomic with reference to the code reading these
variables. See also "Does the update code tolerate concurrent accesses?"
in Documentation/RCU/checklist.txt.

Fixes: commit 09e2b0b1 ("scsi: rescan VPD attributes")
Signed-off-by: NBart Van Assche <bart.vanassche@wdc.com>
Acked-by: NHannes Reinecke <hare@suse.de>
Reviewed-by: NShane Seymour <shane.seymour@hpe.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: Shane Seymour <shane.seymour@hpe.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The kerneldoc comment for scsi_initialize_rq() neglected to document the
"rq" parameter, leading to this docs build warning:

  ./drivers/scsi/scsi_lib.c:1116: warning: No description found for parameter 'rq'

Document the parameter and make the build slightly quieter.

[mkp: used wording suggested by Bart]
Signed-off-by: NJonathan Corbet <corbet@lwn.net>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

The function returns '0' if successful; with the original comment
the function doesn't have a way to indicate success ...
Signed-off-by: NHannes Reinecke <hare@suse.de>
Reviewed-by: NBart van Assche <bvanassche@wdc.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Since commit e9c787e6 ("scsi: allocate scsi_cmnd structures as
part of struct request") struct request and struct scsi_cmnd are
adjacent. This means that there is now an alternative to reading
req->special to convert a pointer to a prepared request into a
SCSI command pointer, namely by using blk_mq_rq_to_pdu(). Make
this change where appropriate. Although this patch does not
change any functionality, it slightly improves performance and
slightly improves readability.
Signed-off-by: NBart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Rename several functions to make it easy to see which queue type a
function is intended for.
Signed-off-by: NBart Van Assche <bart.vanassche@sandisk.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

While the 'state' attribute can (and will) change occasionally,
calling 'poll()' or 'select()' on it fails as sysfs is never
notified that the state has changed.
With this patch calling 'poll()' or 'select()' will work
properly.
Signed-off-by: NHannes Reinecke <hare@suse.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Rework scsi_internal_device_unblock_nowait() into using a switch
statement. No functional changes.
Signed-off-by: NHannes Reinecke <hare@suse.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

Since scsi_req_init() works on a struct scsi_request, change the
argument type into struct scsi_request *.
Signed-off-by: NBart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Reviewed-by: NMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Instead of explicitly calling scsi_req_init() after blk_get_request(),
call that function from inside blk_get_request(). Add an
.initialize_rq_fn() callback function to the block drivers that need
it. Merge the IDE .init_rq_fn() function into .initialize_rq_fn()
because it is too small to keep it as a separate function. Keep the
scsi_req_init() call in ide_prep_sense() because it follows a
blk_rq_init() call.

References: commit 82ed4db4 ("block: split scsi_request out of struct request")
Signed-off-by: NBart Van Assche <bart.vanassche@sandisk.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

blk_mq_unquiesce_queue() is used for unquiescing the
queue explicitly, so replace blk_mq_start_stopped_hw_queues()
with it.

For the scsi part, this patch takes Bart's suggestion to
switch to block quiesce/unquiesce API completely.

Cc: linux-nvme@lists.infradead.org
Cc: linux-scsi@vger.kernel.org
Cc: dm-devel@redhat.com
Reviewed-by: NBart Van Assche <Bart.VanAssche@sandisk.com>
Signed-off-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This patch reduces code duplication. There are two functional changes in
this patch:

- It causes scsi_mq_prep_fn() to clear driver-private command data, just
  like the already upstream commit 1bad6c4a ("scsi: zero per-cmd
  private driver data for each MQ I/O").

- The initialization of .prot_sdb is moved from scsi_mq_prep_fn() into
  scsi_init_request().

[mkp: applied by hand]
Signed-off-by: NBart Van Assche <bart.vanassche@sandisk.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

This patch does not change any functionality but makes the next patch
easier to read.
Signed-off-by: NBart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>