Return an errno value instead of the passed in queue so that the callers
don't have to keep track of two queues, and move the assignment of the
request_fn and lock to the caller as passing them as argument doesn't
simplify anything.  While we're at it also remove two pointless NULL
assignments, given that the request structure is zeroed on allocation.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

We can't initalize the elevator fields for flushes as flush share space
in struct request with the elevator data.  But currently we can't
communicate that a request is a flush through blk_get_request as we
can only pass READ or WRITE, and the low-level code looks at the
possible NULL bio to check for a flush.

Fix this by allowing to pass any block op and flags, and by checking for
the flush flags in __get_request.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

No need for the local variables, the bio is still live and we can just
assign the bits we want directly.  Make me wonder why we can't assign
all the bio flags to start with.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

Signed-off-by: Jens Axboe <axboe@fb.com>

This fixes a couple of problems:

1. In the !CONFIG_DEBUG_FS case, the stub definitions were bogus.
2. In the !CONFIG_BLOCK case, blk-mq-debugfs.c shouldn't be compiled at
   all.

Fix the stub definitions and add a CONFIG_BLK_DEBUG_FS Kconfig option.

Fixes: 07e4fead ("blk-mq: create debugfs directory tree")
Signed-off-by: Omar Sandoval <osandov@fb.com>

Augment Kconfig description.
Signed-off-by: Jens Axboe <axboe@fb.com>

Use op_is_flush() where applicable.
Signed-off-by: Jens Axboe <axboe@fb.com>

Instead of letting the caller check this and handle the details
of inserting a flush request, put the logic in the scheduler
insertion function. This fixes direct flush insertion outside
of the usual make_request_fn calls, like from dm via
blk_insert_cloned_request().
Signed-off-by: Jens Axboe <axboe@fb.com>

This centralizes the checks for bios that needs to be go into the flush
state machine.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

When we invoke dispatch_requests(), the scheduler empties everything
into the passed in list. This isn't always a good thing, since it
means that we remove items that we could have potentially merged
with.

Change the function to dispatch single requests at the time. If
we do that, we can backoff exactly at the point where the device
can't consume more IO, and leave the rest with the scheduler for
better merging and future dispatch decision making.
Signed-off-by: Jens Axboe <axboe@fb.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Tested-by: Hannes Reinecke <hare@suse.com>

If we have both multiple hardware queues and shared tag map between
devices, we need to ensure that we propagate the hardware queue
restart bit higher up. This is because we can get into a situation
where we don't have any IO pending on a hardware queue, yet we fail
getting a tag to start new IO. If that happens, it's not enough to
mark the hardware queue as needing a restart, we need to bubble
that up to the higher level queue as well.
Signed-off-by: Jens Axboe <axboe@fb.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Tested-by: Hannes Reinecke <hare@suse.com>

We don't want to hold on to this resource when we have a scheduler
attached.
Signed-off-by: Jens Axboe <axboe@fb.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Tested-by: Hannes Reinecke <hare@suse.com>

Once we mark the queue as needing a restart, re-check if we can
get a driver tag. This fixes a theoretical issue where the needed
IO completes _after_ blk_mq_get_driver_tag() fails, but before we
manage to set the restart bit.
Signed-off-by: Jens Axboe <axboe@fb.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Tested-by: Hannes Reinecke <hare@suse.com>

We'll use the same criteria for whether we need to run the queue sync
or async when we have a scheduler, as we do without one.
Signed-off-by: Jens Axboe <axboe@fb.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Tested-by: Hannes Reinecke <hare@suse.com>

These counters aren't as out-of-place in sysfs as the other stuff, but
debugfs is a slightly better home for them.
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

These statistics _might_ be useful to userspace, but it's better not to
commit to an ABI for these yet. Also, the dispatched file in sysfs
couldn't be cleared, so make it clearable like the others in debugfs.
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

These can be used to debug issues like tag leaks and stuck requests.
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

These are very tied to the blk-mq tag implementation, so exposing them
to sysfs isn't a great idea. Move the debugging information to debugfs
and add basic entries for the number of tags and the number of reserved
tags to sysfs.
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

This is useful for debugging problems where we've gotten stuck with
requests in the software queues.
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

This is useful debugging information that will be used in the blk-mq
debugfs directory.
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>

Changed 'weight' to 'busy'.
Signed-off-by: Jens Axboe <axboe@fb.com>

The request pointers by themselves aren't super useful.
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

These lists are only useful for debugging; they definitely don't belong
in sysfs. Putting them in debugfs also removes the limitation of a
single page of output.
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

hctx->state could come in handy for bugs where the hardware queue gets
stuck in the stopped state, and hctx->flags is just useful to know.
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

In preparation for putting blk-mq debugging information in debugfs,
create a directory tree mirroring the one in sysfs:

    # tree -d /sys/kernel/debug/block
    /sys/kernel/debug/block
    |-- nvme0n1
    |   `-- mq
    |       |-- 0
    |       |   `-- cpu0
    |       |-- 1
    |       |   `-- cpu1
    |       |-- 2
    |       |   `-- cpu2
    |       `-- 3
    |           `-- cpu3
    `-- vda
        `-- mq
            `-- 0
                |-- cpu0
                |-- cpu1
                |-- cpu2
                `-- cpu3

Also add the scaffolding for the actual files that will go in here,
either under the hardware queue or software queue directories.
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

We don't trigger this from the normal IO path, since we always use
blocking allocations from there. But Bart saw it testing multipath
dm, since that is a heavy user of atomic request allocations in
the map and clone path.
Reported-by: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

If we come in from blk_mq_alloc_requst() with NOWAIT set in flags,
we must ensure that we don't later overwrite that in
blk_mq_sched_get_request(). Initialize alloc_data->flags before
passing it in.
Reported-by: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

If we have a scheduler attached, we have two sets of tags. We don't
want to apply our active queue throttling for the scheduler side
of tags, that only applies to driver tags since that's the resource
we need to dispatch an IO.
Signed-off-by: Jens Axboe <axboe@fb.com>

The script "checkpatch.pl" pointed information out like the following.

ERROR: do not use assignment in if condition

Thus fix the affected source code place.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Jens Axboe <axboe@fb.com>

The script "checkpatch.pl" pointed information out like the following.

ERROR: do not use assignment in if condition

Thus fix the affected source code places.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@fb.com>

KMSAN (KernelMemorySanitizer, a new error detection tool) reports use of
uninitialized memory in cfq_init_cfqq():

==================================================================
BUG: KMSAN: use of unitialized memory
...
Call Trace:
 [<     inline     >] __dump_stack lib/dump_stack.c:15
 [<ffffffff8202ac97>] dump_stack+0x157/0x1d0 lib/dump_stack.c:51
 [<ffffffff813e9b65>] kmsan_report+0x205/0x360 ??:?
 [<ffffffff813eabbb>] __msan_warning+0x5b/0xb0 ??:?
 [<     inline     >] cfq_init_cfqq block/cfq-iosched.c:3754
 [<ffffffff8201e110>] cfq_get_queue+0xc80/0x14d0 block/cfq-iosched.c:3857
...
origin:
 [<ffffffff8103ab37>] save_stack_trace+0x27/0x50 arch/x86/kernel/stacktrace.c:67
 [<ffffffff813e836b>] kmsan_internal_poison_shadow+0xab/0x150 ??:?
 [<ffffffff813e88ab>] kmsan_poison_slab+0xbb/0x120 ??:?
 [<     inline     >] allocate_slab mm/slub.c:1627
 [<ffffffff813e533f>] new_slab+0x3af/0x4b0 mm/slub.c:1641
 [<     inline     >] new_slab_objects mm/slub.c:2407
 [<ffffffff813e0ef3>] ___slab_alloc+0x323/0x4a0 mm/slub.c:2564
 [<     inline     >] __slab_alloc mm/slub.c:2606
 [<     inline     >] slab_alloc_node mm/slub.c:2669
 [<ffffffff813dfb42>] kmem_cache_alloc_node+0x1d2/0x1f0 mm/slub.c:2746
 [<ffffffff8201d90d>] cfq_get_queue+0x47d/0x14d0 block/cfq-iosched.c:3850
...
==================================================================
(the line numbers are relative to 4.8-rc6, but the bug persists
upstream)

The uninitialized struct cfq_queue is created by kmem_cache_alloc_node()
and then passed to cfq_init_cfqq(), which accesses cfqq->ioprio_class
before it's initialized.
Signed-off-by: Alexander Potapenko <glider@google.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

Pull x86 fix from Thomas Gleixner:
 "Restore the retrigger callbacks in the IO APIC irq chips. That
  addresses a long standing regression which got introduced with the
  rewrite of the x86 irq subsystem two years ago and went unnoticed so
  far"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/ioapic: Restore IO-APIC irq_chip retrigger callback

Pull smp/hotplug fix from Thomas Gleixner:
 "Remove an unused variable which is a leftover from the notifier
  removal"

* 'smp-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  cpu/hotplug: Remove unused but set variable in _cpu_down()

Pull virtio/vhost fixes from Michael Tsirkin:
 "Random fixes and cleanups that accumulated over the time"

* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
  virtio/s390: virtio: constify virtio_config_ops structures
  virtio/s390: add missing \n to end of dev_err message
  virtio/s390: support READ_STATUS command for virtio-ccw
  tools/virtio/ringtest: tweaks for s390
  tools/virtio/ringtest: fix run-on-all.sh for offline cpus
  virtio_console: fix a crash in config_work_handler
  vhost/scsi: silence uninitialized variable warning
  vhost: scsi: constify target_core_fabric_ops structures

Pull thermal management fixes from Zhang Rui:

 - fix a regression that thermal zone dynamically allocated sysfs
   attributes are freed before they're removed, which is introduced in
   4.10-rc1 (Jacob von Chorus)

 - fix a boot warning because deprecated hwmon API is used (Fabio
   Estevam)

 - a couple of fixes for rockchip thermal driver (Brian Norris, Caesar
   Wang)

* 'for-rc' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux:
  thermal: rockchip: fixes the conversion table
  thermal: core: move tz->device.groups cleanup to thermal_release
  thermal: thermal_hwmon: Convert to hwmon_device_register_with_info()
  thermal: rockchip: handle set_trips without the trip points
  thermal: rockchip: optimize the conversion table
  thermal: rockchip: fixes invalid temperature case
  thermal: rockchip: don't pass table structs by value
  thermal: rockchip: improve conversion error messages

Pull USB fixes from Greg KH:
 "Here are a few small USB fixes for 4.10-rc5.

  Most of these are gadget/dwc2 fixes for reported issues, all of these
  have been in linux-next for a while. The last one is a single xhci
  WARN_ON removal to handle an issue that the dwc3 driver is hitting in
  the 4.10-rc tree. The warning is harmless and needs to be removed, and
  a "real" fix that is more complex will show up in 4.11-rc1 for this
  device.

  That last patch hasn't been in linux-next yet due to the weekend
  timing, but it's a "simple" WARN_ON() removal so what could go wrong?
  :)"

Famous last words.

* tag 'usb-4.10-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb:
  xhci: remove WARN_ON if dma mask is not set for platform devices
  usb: dwc2: host: fix Wmaybe-uninitialized warning
  usb: dwc2: gadget: Fix GUSBCFG.USBTRDTIM value
  usb: gadget: udc: atmel: remove memory leak
  usb: dwc3: exynos fix axius clock error path to do cleanup
  usb: dwc2: Avoid suspending if we're in gadget mode
  usb: dwc2: use u32 for DT binding parameters
  usb: gadget: f_fs: Fix iterations on endpoints.
  usb: dwc2: gadget: Fix DMA memory freeing
  usb: gadget: composite: Fix function used to free memory

Pull libnvdimm fixes from Dan Williams:
 "Two fixes:

   - a regression fix for the multiple-pmem-namespace-per-region support
     added in 4.9. Even if an existing environment is not using that
     feature the act of creating and a destroying a single namespace
     with the ndctl utility will lead to the proliferation of extra
     unwanted namespace devices.

   - a fix for the error code returned from the pmem driver when the
     memcpy_mcsafe() routine returns -EFAULT. Btrfs seems to be the only
     block I/O consumer that tries to parse the meaning of the error
     code when it is non-zero.

  Neither of these fixes are critical, the namespace leak is awkward in
  that it can cause device naming to change and complicates debugging
  namespace initialization issues. The error code fix is included out of
  caution for what other consumers might be expecting -EIO for block I/O
  errors"

* 'libnvdimm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
  libnvdimm, namespace: fix pmem namespace leak, delete when size set to zero
  pmem: return EIO on read_pmem() failure

Pull clk fix from Stephen Boyd:
 "One fix for Samsung Exynos524x SoCs where recent IOMMU patches have
  caused some of these clocks to turn off when they were always left on
  before"

* tag 'clk-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux:
  clk/samsung: exynos542x: mark some clocks as critical

Pull ARC fixes from Vineet Gupta:

 - more intc updates [Yuriv]

 - fix module build when unwinder is turned off

 - IO Coherency Programming model updates

 - other miscellaneous

* tag 'arc-4.10-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc:
  ARC: Revert "ARC: mm: IOC: Don't enable IOC by default"
  ARC: mm: split arc_cache_init to allow __init reaping of bulk
  ARCv2: IOC: Use actual memory size to setup aperture size
  ARCv2: IOC: Adhere to progamming model guidelines to avoid DMA corruption
  ARCv2: IOC: refactor the IOC and SLC operations into own functions
  ARC: module: Fix !CONFIG_ARC_DW2_UNWIND builds
  ARCv2: save r30 on kernel entry as gcc uses it for code-gen
  ARCv2: IRQ: Call entry/exit functions for chained handlers in MCIP
  ARC: IRQ: Use hwirq instead of virq in mask/unmask
  ARC: mmu: clarify the MMUv3 programming model

Pull powerpc fixes from Michael Ellerman:
 "Two fixes for fallout from the hugetlb changes we merged this cycle.

  Ten other fixes, four only affect Power9, and the rest are a bit of a
  mixture though nothing terrible.

  Thanks to: Aneesh Kumar K.V, Anton Blanchard, Benjamin Herrenschmidt,
  Dave Martin, Gavin Shan, Madhavan Srinivasan, Nicholas Piggin, Reza
  Arbab"

* tag 'powerpc-4.10-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc: Ignore reserved field in DCSR and PVR reads and writes
  powerpc/ptrace: Preserve previous TM fprs/vsrs on short regset write
  powerpc/ptrace: Preserve previous fprs/vsrs on short regset write
  powerpc/perf: Use MSR to report privilege level on P9 DD1
  selftest/powerpc: Wrong PMC initialized in pmc56_overflow test
  powerpc/eeh: Enable IO path on permanent error
  powerpc/perf: Fix PM_BRU_CMPL event code for power9
  powerpc/mm: Fix little-endian 4K hugetlb
  powerpc/mm/hugetlb: Don't panic when we don't find the default huge page size
  powerpc: Fix pgtable pmd cache init
  powerpc/icp-opal: Fix missing KVM case and harden replay
  powerpc/mm: Fix memory hotplug BUG() on radix

Pull KVM fixes from Radim Krčmář:
 "ARM:
   - Fix for timer setup on VHE machines
   - Drop spurious warning when the timer races against the vcpu running
     again
   - Prevent a vgic deadlock when the initialization fails (for stable)

  s390:
   - Fix a kernel memory exposure (for stable)

  x86:
   - Fix exception injection when hypercall instruction cannot be
     patched"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: s390: do not expose random data via facility bitmap
  KVM: x86: fix fixing of hypercalls
  KVM: arm/arm64: vgic: Fix deadlock on error handling
  KVM: arm64: Access CNTHCTL_EL2 bit fields correctly on VHE systems
  KVM: arm/arm64: Fix occasional warning from the timer work function