req->result is cleared when io_issue_sqe() calls io_read/write_pre()
routines.  Those routines however are not called when the sqe
argument is NULL, which is the case when io_issue_sqe() is called from
io_wq_submit_work().  io_issue_sqe() may then examine a stale result if
a polled request had previously failed with -EAGAIN:

        if (ctx->flags & IORING_SETUP_IOPOLL) {
                if (req->result == -EAGAIN)
                        return -EAGAIN;

                io_iopoll_req_issued(req);
        }

and in turn cause a subsequently completed request to be re-issued in
io_wq_submit_work().
Signed-off-by: Bijan Mottahedeh <bijan.mottahedeh@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

If we pass back dependent work in case of links, we need to always
ensure that we call the link setup and work prep handler. If not, we
might be missing some setup for the next work item.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

If we require mm and user context, mark the request for cancellation
if we fail to acquire the desired mm.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

We don't need it, and if we have it, then the retry handler will attempt
to copy the non-existent iovec with the inline iovec, with a segment
count that doesn't make sense.

Fixes: f67676d1 ("io_uring: ensure async punted read/write requests copy iovec")
Reported-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

We currently punt any short read on a regular file to async context,
but this fails if the short read is due to running into EOF. This is
especially problematic since we only do the single prep for commands
now, as we don't reset kiocb->ki_pos. This can result in a 4k read on
a 1k file returning zero, as we detect the short read and then retry
from async context. At the time of retry, the position is now 1k, and
we end up reading nothing, and hence return 0.

Instead of trying to patch around the fact that short reads can be
legitimate and won't succeed in case of retry, remove the logic to punt
a short read to async context. Simply return it.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Reschedule the current IO worker to cut the risk that it is becoming
a cpu hog.
Signed-off-by: Hillf Danton <hdanton@sina.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Commit e61df66c ("io-wq: ensure free/busy list browsing see all
items") added a list for io workers in addition to the free and busy
lists, not only making worker walk cleaner, but leaving the busy list
unused. Let's remove it.
Signed-off-by: Hillf Danton <hdanton@sina.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

This moves the prep handlers outside of the opcode handlers, and allows
us to pass in the sqe directly. If the sqe is non-NULL, it means that
the request should be prepared for the first time.

With the opcode handlers not having access to the sqe at all, we are
guaranteed that the prep handler has setup the request fully by the
time we get there. As before, for opcodes that need to copy in more
data then the io_kiocb allows for, the io_async_ctx holds that info. If
a prep handler is invoked with req->io set, it must use that to retain
information for later.

Finally, we can remove io_kiocb->sqe as well.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

We currently have a mix of use cases. Most of the newer ones are pretty
uniform, but we have some older ones that use different calling
calling conventions. This is confusing.

For the opcodes that currently rely on the req->io->sqe copy saving
them from reuse, add a request type struct in the io_kiocb command
union to store the data they need.

Prepare for all opcodes having a standard prep method, so we can call
it in a uniform fashion and outside of the opcode handler. This is in
preparation for passing in the 'sqe' pointer, rather than storing it
in the io_kiocb. Once we have uniform prep handlers, we can leave all
the prep work to that part, and not even pass in the sqe to the opcode
handler. This ensures that we don't reuse sqe data inadvertently.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Add the count field to struct io_timeout, and ensure the prep handler
has read it. Timeout also needs an async context always, set it up
in the prep handler if we don't have one.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Add struct io_sr_msg in our io_kiocb per-command union, and ensure that
the send/recvmsg prep handlers have grabbed what they need from the SQE
by the time prep is done.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Add struct io_connect in our io_kiocb per-command union, and ensure
that io_connect_prep() has grabbed what it needs from the SQE.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Put the kiocb in struct io_rw, and add the addr/len for the request as
well. Use the kiocb->private field for the buffer index for fixed reads
and writes.

Any use of kiocb->ki_filp is flipped to req->file. It's the same thing,
and less confusing.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

We use it in some spots, but not consistently. Convert the rest over,
makes it easier to read as well.

No functional changes in this patch.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

I've been chasing a weird and obscure crash that was userspace stack
corruption, and finally narrowed it down to a bit flip that made a
stack address invalid. io_wq_submit_work() unconditionally flips
the req->rw.ki_flags IOCB_NOWAIT bit, but since it's a generic work
handler, this isn't valid. Normal read/write operations own that
part of the request, on other types it could be something else.

Move the IOCB_NOWAIT clear to the read/write handlers where it belongs.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

There is no reliable way to submit and wait in a single syscall, as
io_submit_sqes() may under-consume sqes (in case of an early error).
Then it will wait for not-yet-submitted requests, deadlocking the user
in most cases.

Don't wait/poll if can't submit all sqes
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Now that we have all the opcodes handled in terms of command prep and
SQE reuse, add a printk_once() to warn about any potentially new and
unhandled ones.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

If we defer a request, we can't be reading the opcode again. Ensure that
the user_data and opcode fields are stable. For the user_data we already
have a place for it, for the opcode we can fill a one byte hold and store
that as well. For both of them, assign them when we originally read the
SQE in io_get_sqring(). Any code that uses sqe->opcode or sqe->user_data
is switched to req->opcode and req->user_data.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

If we defer this command as part of a link, we have to make sure that
the SQE data has been read upfront. Integrate the timeout remove op into
the prep handling to make it safe for SQE reuse.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

If we defer this command as part of a link, we have to make sure that
the SQE data has been read upfront. Integrate the async cancel op into
the prep handling to make it safe for SQE reuse.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

If we defer these commands as part of a link, we have to make sure that
the SQE data has been read upfront. Integrate the poll add/remove into
the prep handling to make it safe for SQE reuse.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

The rules are as follows, if IOSQE_IO_HARDLINK is specified, then it's a
link and there is no need to set IOSQE_IO_LINK separately, though it
could be there. Add proper check and ensure that IOSQE_IO_HARDLINK
implies IOSQE_IO_LINK.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

We're currently not retaining sqe data for accept, fsync, and
sync_file_range. None of these commands need data outside of what
is directly provided, hence it can't go stale when the request is
deferred. However, it can get reused, if an application reuses
SQE entries.

Ensure that we retain the information we need and only read the sqe
contents once, off the submission path. Most of this is just moving
code into a prep and finish function.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

We pass in req->sqe for all of them, no need to pass it in as the
request is always passed in. This is a necessary prep patch to be
able to cleanup/fix the request prep path.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Some of these code paths assume that any force_nonblock == true issue
is not prepped, but that's not true if we did prep as part of link setup
earlier. Check if we already have an async context allocate before
setting up a new one.

Cleanup the async context setup in general, we have a lot of duplicated
code there.

Fixes: 03b1230c ("io_uring: ensure async punted sendmsg/recvmsg requests copy data")
Fixes: f67676d1 ("io_uring: ensure async punted read/write requests copy iovec")
Signed-off-by: Jens Axboe <axboe@kernel.dk>

This reverts commit 8cdda87a, we now have several use csaes for this
helper. Reinstate it.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

If we have to punt the recvmsg to async context, we copy all the
context.  But since the iovec used can be either on-stack (if small) or
dynamically allocated, if it's on-stack, then we need to ensure we reset
the iov pointer. If we don't, then we're reusing old stack data, and
that can lead to -EFAULTs if things get overwritten.

Ensure we retain the right pointers for the iov, and free it as well if
we end up having to go beyond UIO_FASTIOV number of vectors.

Fixes: 03b1230c ("io_uring: ensure async punted sendmsg/recvmsg requests copy data")
Reported-by: 李通洲 <carter.li@eoitek.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

- Fix a few typos found while reading the code.

- Fix stale io_get_sqring comment referencing s->sqe, the 's' parameter
  was renamed to 'req', but the comment still holds.
Signed-off-by: Brian Gianforcaro <b.gianfo@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Pull nios2 fix from Ley Foon Tan:
 "Fix nios2 ioremap regression"

* tag 'nios2-v5.5-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/lftan/nios2:
  nios2: Fix ioremap

Pull Devicetree fixes from Rob Herring:

 - Fix for dependency tracking caused by unittest interaction

 - Fix some schema errors in Tegra memory controller schema

 - Update Maxime Ripard's email address

 - Review fixes to TI cpsw-switch

 - Add wakeup-source prop for STM32 rproc. Got dropped in the schema
   conversion.

* tag 'devicetree-fixes-for-5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux:
  of/platform: Unconditionally pause/resume sync state during kernel init
  dt-bindings: memory-controllers: tegra: Fix type references
  dt-bindings: Change maintainer address
  dt-bindings: net: ti: cpsw-switch: update to fix comments
  dt-bindings: remoteproc: stm32: add wakeup-source property

Pull virtio fixes from Michael Tsirkin:
 "Some fixes and cleanup patches"

* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost:
  virtio_balloon: divide/multiply instead of shifts
  virtio_balloon: name cleanups
  virtio-balloon: fix managed page counts when migrating pages between zones

Pull PCI fix from Bjorn Helgaas:
 "Fix rockchip outbound ATU issue that prevented Google Kevin
  Chromebooks from booting (Enric Balletbo i Serra)"

* tag 'pci-v5.5-fixes-1' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci:
  PCI: rockchip: Fix IO outbound ATU register number

Pull i2c updates from Wolfram Sang:

 - removal of an old API where all in-kernel users have been converted
   as of this merge window.

 - a kdoc fix

 - a new helper that will make dependencies for the next API conversion
   a tad easier

* 'i2c/for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
  i2c: add helper to check if a client has a driver attached
  i2c: fix header file kernel-doc warning
  i2c: remove i2c_new_dummy() API

Pull power management fixes from Rafael Wysocki:
 "These add PM QoS support to devfreq and fix a few issues in that
  subsystem, fix two cpuidle issues and do one minor cleanup in there,
  and address an ACPI power management problem related to devices with
  special power management requirements, like fans.

  Specifics:

   - Add PM QoS support, based on the frequency QoS introduced during
     the 5.4 cycle, to devfreq (Leonard Crestez).

   - Fix some assorted devfreq issues (Leonard Crestez).

   - Fix an unintentional cpuidle behavior change (introduced during the
     5.4 cycle) related to the active polling time limit (Marcelo
     Tosatti).

   - Fix a recently introduced cpuidle helper function and do a minor
     cleanup in the cpuidle core (Rafael Wysocki).

   - Avoid adding devices with special power management requirements,
     like fans, to the generic ACPI PM domain (Rafael Wysocki)"

* tag 'pm-5.5-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  cpuidle: Drop unnecessary type cast in cpuidle_poll_time()
  cpuidle: Fix cpuidle_driver_state_disabled()
  ACPI: PM: Avoid attaching ACPI PM domain to certain devices
  cpuidle: use first valid target residency as poll time
  PM / devfreq: Use PM QoS for sysfs min/max_freq
  PM / devfreq: Add PM QoS support
  PM / devfreq: Don't fail devfreq_dev_release if not in list
  PM / devfreq: Introduce get_freq_range helper
  PM / devfreq: Set scaling_max_freq to max on OPP notifier error
  PM / devfreq: Fix devfreq_notifier_call returning errno

Pull sound fixes from Takashi Iwai:
 "A small collection of fixes.

  The main changes are fixes for a couple of regressions in AMD HD-audio
  and FireWire that were introduced in 5.5-rc1. The rest are small fixes
  for echoaudio and FireWire, as well as a usual Dell HD-audio fixup"

* tag 'sound-5.5-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound:
  ALSA: hda/realtek - Line-out jack doesn't work on a Dell AIO
  ALSA: hda/hdmi - Fix duplicate unref of pci_dev
  ALSA: fireface: fix return value in error path of isochronous resources reservation
  ALSA: oxfw: fix return value in error path of isochronous resources reservation
  ALSA: firewire-motu: fix double unlocked 'motu->mutex'
  ALSA: echoaudio: simplify get_audio_levels

Pull drm fixes from Dave Airlie:
 "Usual round of rc2 fixes.

  i915 and amdgpu leading the charge, but a few others in here,
  including some nouveau fixes, all seems pretty for rc2, but hey it's a
  Fri 13th pull so I'm sure it'll cause untold bad fortune.

  dma-buf:
   - memory leak fix
   - expand MAINTAINERS scope

  core:
   - fix mode matching for drivers not using picture_aspect_ratio

  nouveau:
   - panel scaling fix
   - MST BPC fix
   - atomic fixes

  i915:
   - GPU hang on idle transition
   - GLK+ FBC corruption fix
   - non-priv OA access on Tigerlake
   - HDCP state fix
   - CI found race fixes

  amdgpu:
   - renoir DC fixes
   - GFX8 fence flush alignment with userspace
   - Arcturus power profile fix
   - DC aux + i2c over aux fixes
   - GPUVM invalidation semaphore fixes
   - gfx10 golden registers update

  mgag200:
   - expand startadd fix

  panfrost:
   - devfreq fix
   - memory fixes

  mcde:
   - DSI pointer deref fix"

* tag 'drm-fixes-2019-12-13' of git://anongit.freedesktop.org/drm/drm: (51 commits)
  drm/amdgpu: add invalidate semaphore limit for SRIOV in gmc10
  drm/amdgpu: add invalidate semaphore limit for SRIOV and picasso in gmc9
  drm/amdgpu: avoid using invalidate semaphore for picasso
  Revert "drm/amdgpu: dont schedule jobs while in reset"
  drm/amdgpu: fix license on Kconfig and Makefiles
  drm/amdgpu/gfx10: update gfx golden settings for navi14
  drm/amdgpu/gfx10: update gfx golden settings
  drm/amdgpu/gfx10: update gfx golden settings for navi14
  drm/amdgpu/gfx10: update gfx golden settings
  drm/i915: Serialise with remote retirement
  drm/amd/display: include linux/slab.h where needed
  drm/amd/display: fix undefined struct member reference
  drm/nouveau/kms/nv50-: fix panel scaling
  drm/nouveau/kms/nv50-: Limit MST BPC to 8
  drm/nouveau/kms/nv50-: Store the bpc we're using in nv50_head_atom
  drm/nouveau/kms/nv50-: Call outp_atomic_check_view() before handling PBN
  drm/nouveau: Fix drm-core using atomic code-paths on pre-nv50 hardware
  drm/nouveau: Move the declaration of struct nouveau_conn_atom up a bit
  drm/i915/gt: Detect if we miss WaIdleLiteRestore
  drm/i915/hdcp: Nuke intel_hdcp_transcoder_config()
  ...

Pull block fixes from Jens Axboe:

 - stable fix for the bi_size overflow. Not a corruption issue, but a
   case wher we could merge but disallowed (Andreas)

 - NVMe pull request via Keith, with various fixes.

 - MD pull request from Song.

 - Merge window regression fix for the rq passthrough stats (Logan)

 - Remove unused blkcg_drain_queue() function (Guoqing)

* tag 'for-linus-20191212' of git://git.kernel.dk/linux-block:
  blk-cgroup: remove blkcg_drain_queue
  block: fix NULL pointer dereference in account statistics with IDE
  md: make sure desc_nr less than MD_SB_DISKS
  md: raid1: check rdev before reference in raid1_sync_request func
  raid5: need to set STRIPE_HANDLE for batch head
  block: fix "check bi_size overflow before merge"
  nvme/pci: Fix read queue count
  nvme/pci Limit write queue sizes to possible cpus
  nvme/pci: Fix write and poll queue types
  nvme/pci: Remove last_cq_head
  nvme: Namepace identification descriptor list is optional
  nvme-fc: fix double-free scenarios on hw queues
  nvme: else following return is not needed
  nvme: add error message on mismatching controller ids
  nvme_fc: add module to ops template to allow module references
  nvmet-loop: Avoid preallocating big SGL for data
  nvme-fc: Avoid preallocating big SGL for data
  nvme-rdma: Avoid preallocating big SGL for data

Pull io_uring fixes from Jens Axboe:

 - A tweak to IOSQE_IO_LINK (also marked for stable) to allow links that
   don't sever if the result is < 0.

   This is mostly for linked timeouts, where if we ask for a pure
   timeout we always get -ETIME. This makes links useless for that case,
   hence allow a case where it works.

 - Five minor optimizations to fix and improve cases that regressed
   since v5.4.

 - An SQTHREAD locking fix.

 - A sendmsg/recvmsg iov assignment fix.

 - Net fix where read_iter/write_iter don't honor IOCB_NOWAIT, and
   subsequently ensuring that works for io_uring.

 - Fix a case where for an invalid opcode we might return -EBADF instead
   of -EINVAL, if the ->fd of that sqe was set to an invalid fd value.

* tag 'io_uring-5.5-20191212' of git://git.kernel.dk/linux-block:
  io_uring: ensure we return -EINVAL on unknown opcode
  io_uring: add sockets to list of files that support non-blocking issue
  net: make socket read/write_iter() honor IOCB_NOWAIT
  io_uring: only hash regular files for async work execution
  io_uring: run next sqe inline if possible
  io_uring: don't dynamically allocate poll data
  io_uring: deferred send/recvmsg should assign iov
  io_uring: sqthread should grab ctx->uring_lock for submissions
  io-wq: briefly spin for new work after finishing work
  io-wq: remove worker->wait waitqueue
  io_uring: allow unbreakable links

Merge tag 'for-5.5/dm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

Pull device mapper fixes from Mike Snitzer:

 - Fix DM multipath by restoring full path selector functionality for
   bio-based configurations that don't haave a SCSI device handler.

 - Fix dm-btree removal to ensure non-root btree nodes have at least
   (max_entries / 3) entries. This resolves userspace thin_check
   utility's report of "too few entries in btree_node".

 - Fix both the DM thin-provisioning and dm-clone targets to properly
   flush the data device prior to metadata commit. This resolves the
   potential for inconsistency across a power loss event when the data
   device has a volatile writeback cache.

 - Small documentation fixes to dm-clone and dm-integrity.

* tag 'for-5.5/dm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
  docs: dm-integrity: remove reference to ARC4
  dm thin: Flush data device before committing metadata
  dm thin metadata: Add support for a pre-commit callback
  dm clone: Flush destination device before committing metadata
  dm clone metadata: Use a two phase commit
  dm clone metadata: Track exact changes per transaction
  dm btree: increase rebalance threshold in __rebalance2()
  dm: add dm-clone to the documentation index
  dm mpath: remove harmful bio-based optimization

Pull FIELD_SIZEOF conversion from Kees Cook:
 "A mostly mechanical treewide conversion from FIELD_SIZEOF() to
  sizeof_field(). This avoids the redundancy of having 2 macros
  (actually 3) doing the same thing, and consolidates on sizeof_field().
  While "field" is not an accurate name, it is the common name used in
  the kernel, and doesn't result in any unintended innuendo.

  As there are still users of FIELD_SIZEOF() in -next, I will clean up
  those during this coming development cycle and send the final old
  macro removal patch at that time"

* tag 'sizeof_field-v5.5-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  treewide: Use sizeof_field() macro
  MIPS: OCTEON: Replace SIZEOF_FIELD() macro