Provide the completion state to the handlers that we know can complete
inline, so they can utilize this for batching completions.

Cap the max batch count at 32. This should be enough to provide a good
amortization of the cost of the lock+commit dance for completions, while
still being low enough not to cause any real latency issues for SQPOLL
applications.

Xuan Zhuo <xuanzhuo@linux.alibaba.com> reports that this changes his
profile from:

17.97% [kernel] [k] copy_user_generic_unrolled
13.92% [kernel] [k] io_commit_cqring
11.04% [kernel] [k] __io_cqring_fill_event
10.33% [kernel] [k] udp_recvmsg
 5.94% [kernel] [k] skb_release_data
 4.31% [kernel] [k] udp_rmem_release
 2.68% [kernel] [k] __check_object_size
 2.24% [kernel] [k] __slab_free
 2.22% [kernel] [k] _raw_spin_lock_bh
 2.21% [kernel] [k] kmem_cache_free
 2.13% [kernel] [k] free_pcppages_bulk
 1.83% [kernel] [k] io_submit_sqes
 1.38% [kernel] [k] page_frag_free
 1.31% [kernel] [k] inet_recvmsg

to

19.99% [kernel] [k] copy_user_generic_unrolled
11.63% [kernel] [k] skb_release_data
 9.36% [kernel] [k] udp_rmem_release
 8.64% [kernel] [k] udp_recvmsg
 6.21% [kernel] [k] __slab_free
 4.39% [kernel] [k] __check_object_size
 3.64% [kernel] [k] free_pcppages_bulk
 2.41% [kernel] [k] kmem_cache_free
 2.00% [kernel] [k] io_submit_sqes
 1.95% [kernel] [k] page_frag_free
 1.54% [kernel] [k] io_put_req
[...]
 0.07% [kernel] [k] io_commit_cqring
 0.44% [kernel] [k] __io_cqring_fill_event
Signed-off-by: Jens Axboe <axboe@kernel.dk>

No functional changes in this patch, just in preparation for having the
completion state be available on the issue side. Later on, this will
allow requests that complete inline to be completed in batches.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

No functional changes in this patch, just in preparation for passing back
pending completions to the caller and completing them in a batched
fashion.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

We have lots of callers of:

io_cqring_add_event(req, result);
io_put_req(req);

Provide a helper that does this for us. It helps clean up the code, and
also provides a more convenient location for us to change the completion
handling.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

__io_queue_sqe() tries to handle all request of a link,
so it's not enough to grab mm in io_sq_thread_acquire_mm()
based just on the head.

Don't check req->needs_mm and do it always.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>

After recent changes, io_submit_sqes() always passes valid submit state,
so kill leftovers checking it for NULL.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

It's a good practice to modify fields of a struct after but not before
it was initialised. Even though io_init_poll_iocb() doesn't touch
poll->file, call it first.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

REQ_F_MUST_PUNT may seem looking good and clear, but it's the same
as not having REQ_F_NOWAIT set. That rather creates more confusion.
Moreover, it doesn't even affect any behaviour (e.g. see the patch
removing it from io_{read,write}).

Kill theg flag and update already outdated comments.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_{read,write}() {
	...
copy_iov: // prep async
  	if (!(flags & REQ_F_NOWAIT) && !file_can_poll(file))
		flags |= REQ_F_MUST_PUNT;
}

REQ_F_MUST_PUNT there is pointless, because if it happens then
REQ_F_NOWAIT is known to be _not_ set, and the request will go
async path in __io_queue_sqe() anyway. file_can_poll() check
is also repeated in arm_poll*(), so don't need it.

Remove the mentioned assignment REQ_F_MUST_PUNT in preparation
for killing the flag.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Pull in async buffered reads branch.

* async-buffered.8:
  io_uring: support true async buffered reads, if file provides it
  mm: add kiocb_wait_page_queue_init() helper
  btrfs: flag files as supporting buffered async reads
  xfs: flag files as supporting buffered async reads
  block: flag block devices as supporting IOCB_WAITQ
  fs: add FMODE_BUF_RASYNC
  mm: support async buffered reads in generic_file_buffered_read()
  mm: add support for async page locking
  mm: abstract out wake_page_match() from wake_page_function()
  mm: allow read-ahead with IOCB_NOWAIT set
  io_uring: re-issue block requests that failed because of resources
  io_uring: catch -EIO from buffered issue request failure
  io_uring: always plug for any number of IOs
  block: provide plug based way of signaling forced no-wait semantics

If the file is flagged with FMODE_BUF_RASYNC, then we don't have to punt
the buffered read to an io-wq worker. Instead we can rely on page
unlocking callbacks to support retry based async IO. This is a lot more
efficient than doing async thread offload.

The retry is done similarly to how we handle poll based retry. From
the unlock callback, we simply queue the retry to a task_work based
handler.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Checks if the file supports it, and initializes the values that we need.
Caller passes in 'data' pointer, if any, and the callback function to
be used.
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

btrfs uses generic_file_read_iter(), which already supports this.
Acked-by: Chris Mason <clm@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

XFS uses generic_file_read_iter(), which already supports this.
Acked-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Signed-off-by: Jens Axboe <axboe@kernel.dk>

If set, this indicates that the file system supports IOCB_WAITQ for
buffered reads.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Use the async page locking infrastructure, if IOCB_WAITQ is set in the
passed in iocb. The caller must expect an -EIOCBQUEUED return value,
which means that IO is started but not done yet. This is similar to how
O_DIRECT signals the same operation. Once the callback is received by
the caller for IO completion, the caller must retry the operation.
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Normally waiting for a page to become unlocked, or locking the page,
requires waiting for IO to complete. Add support for lock_page_async()
and wait_on_page_locked_async(), which are callback based instead. This
allows a caller to get notified when a page becomes unlocked, rather
than wait for it.

We add a new iocb field, ki_waitq, to pass in the necessary data for this
to happen. We can unionize this with ki_cookie, since that is only used
for polled IO. Polled IO can never co-exist with async callbacks, as it is
(by definition) polled completions. struct wait_page_key is made public,
and we define struct wait_page_async as the interface between the caller
and the core.
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

No functional changes in this patch, just in preparation for allowing
more callers.
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

The read-ahead shouldn't block, so allow it to be done even if
IOCB_NOWAIT is set in the kiocb.
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Mark the plug with nowait == true, which will cause requests to avoid
blocking on request allocation. If they do, we catch them and reissue
them from a task_work based handler.

Normally we can catch -EAGAIN directly, but the hard case is for split
requests. As an example, the application issues a 512KB request. The
block core will split this into 128KB if that's the max size for the
device. The first request issues just fine, but we run into -EAGAIN for
some latter splits for the same request. As the bio is split, we don't
get to see the -EAGAIN until one of the actual reads complete, and hence
we cannot handle it inline as part of submission.

This does potentially cause re-reads of parts of the range, as the whole
request is reissued. There's currently no better way to handle this.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

-EIO bubbles up like -EAGAIN if we fail to allocate a request at the
lower level. Play it safe and treat it like -EAGAIN in terms of sync
retry, to avoid passing back an errant -EIO.

Catch some of these early for block based file, as non-mq devices
generally do not support NOWAIT. That saves us some overhead by
not first trying, then retrying from async context. We can go straight
to async punt instead.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Currently we only plug if we're doing more than two request. We're going
to be relying on always having the plug there to pass down information,
so plug unconditionally.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Provide a way for the caller to specify that IO should be marked
with REQ_NOWAIT to avoid blocking on allocation.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Ring pages are not pinned so it is more appropriate to report them
as locked.
Signed-off-by: Bijan Mottahedeh <bijan.mottahedeh@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Report pinned memory usage always, regardless of whether locked memory
limit is enforced.
Signed-off-by: Bijan Mottahedeh <bijan.mottahedeh@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Rename account_mem to limit_name to clarify its purpose.
Signed-off-by: Bijan Mottahedeh <bijan.mottahedeh@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Facilitate separation of locked memory usage reporting vs. limiting for
upcoming patches.  No functional changes.
Signed-off-by: Bijan Mottahedeh <bijan.mottahedeh@oracle.com>
[axboe: kill unnecessary () around return in io_account_mem()]
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Applications can pass this flag in to avoid accept thundering herd.
Signed-off-by: Jiufei Xue <jiufei.xue@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

poll events should be 32-bits to cover EPOLLEXCLUSIVE.

Explicit word-swap the poll32_events for big endian to make sure the ABI
is not changed.  We call this feature IORING_FEAT_POLL_32BITS,
applications who want to use EPOLLEXCLUSIVE should check the feature bit
first.
Signed-off-by: Jiufei Xue <jiufei.xue@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Pull SELinux fixes from Paul Moore:
 "Three small patches to fix problems in the SELinux code, all found via
  clang.

  Two patches fix potential double-free conditions and one fixes an
  undefined return value"

* tag 'selinux-pr-20200621' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
  selinux: fix undefined return of cond_evaluate_expr
  selinux: fix a double free in cond_read_node()/cond_read_list()
  selinux: fix double free

Pull pin control fixes from Linus Walleij:
 "Some early fixes collected during the first week after the merge
  window, all pretty self-evident, with the details below. The revert is
  the crucial thing.

   - Fix a warning on the Qualcomm SPMI GPIO chip being instatiated
     twice without a unique irqchip struct

   - Use the noirq variants of the suspend and resume callbacks in the
     Tegra driver

   - Clean up the errorpath on the MCP23s08 driver

   - Revert the use of devm_of_iomap() in the Freescale driver as it was
     regressing the platform

   - Add some missing pins in the Qualcomm IPQ6018 driver

   - Fix a simple documentation bug in the pinctrl-single driver"

* tag 'pinctrl-v5.8-2' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl:
  pinctrl: single: fix function name in documentation
  pinctrl: qcom: ipq6018 Add missing pins in qpic pin group
  Revert "pinctrl: freescale: imx: Use 'devm_of_iomap()' to avoid a resource leak in case of error in 'imx_pinctrl_probe()'"
  pinctrl: mcp23s08: Split to three parts: fix ptr_ret.cocci warnings
  pinctrl: tegra: Use noirq suspend/resume callbacks
  pinctrl: qcom: spmi-gpio: fix warning about irq chip reusage

Merge tag 'kbuild-fixes-v5.8' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild fixes from Masahiro Yamada:

 - fix -gz=zlib compiler option test for CONFIG_DEBUG_INFO_COMPRESSED

 - improve cc-option in scripts/Kbuild.include to clean up temp files

 - improve cc-option in scripts/Kconfig.include for more reliable
   compile option test

 - do not copy modules.builtin by 'make install' because it would break
   existing systems

 - use 'userprogs' syntax for watch_queue sample

* tag 'kbuild-fixes-v5.8' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  samples: watch_queue: build sample program for target architecture
  Revert "Makefile: install modules.builtin even if CONFIG_MODULES=n"
  scripts: Fix typo in headers_install.sh
  kconfig: unify cc-option and as-option
  kbuild: improve cc-option to clean up all temporary files
  Makefile: Improve compressed debug info support detection

Pull powerpc fixes from Michael Ellerman:

 - One fix for the interrupt rework we did last release which broke
   KVM-PR

 - Three commits fixing some fallout from the READ_ONCE() changes
   interacting badly with our 8xx 16K pages support, which uses a pte_t
   that is a structure of 4 actual PTEs

 - A cleanup of the 8xx pte_update() to use the newly added pmd_off()

 - A fix for a crash when handling an oops if CONFIG_DEBUG_VIRTUAL is
   enabled

 - A minor fix for the SPU syscall generation

Thanks to Aneesh Kumar K.V, Christian Zigotzky, Christophe Leroy, Mike
Rapoport, Nicholas Piggin.

* tag 'powerpc-5.8-3' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/8xx: Provide ptep_get() with 16k pages
  mm: Allow arches to provide ptep_get()
  mm/gup: Use huge_ptep_get() in gup_hugepte()
  powerpc/syscalls: Use the number when building SPU syscall table
  powerpc/8xx: use pmd_off() to access a PMD entry in pte_update()
  powerpc/64s: Fix KVM interrupt using wrong save area
  powerpc: Fix kernel crash in show_instructions() w/DEBUG_VIRTUAL

Pull crypto fixes from Herbert Xu:

 - NULL dereference in octeontx

 - PM reference imbalance in ks-sa

 - deadlock in crypto manager

 - memory leak in drbg

 - missing socket limit check on receive SG list size in algif_skcipher

 - typos in caam

 - warnings in ccp and hisilicon

* 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6:
  crypto: drbg - always try to free Jitter RNG instance
  crypto: marvell/octeontx - Fix a potential NULL dereference
  crypto: algboss - don't wait during notifier callback
  crypto: caam - fix typos
  crypto: ccp - Fix sparse warnings in sev-dev
  crypto: hisilicon - Cap block size at 2^31
  crypto: algif_skcipher - Cap recv SG list at ctx->used
  hwrng: ks-sa - Fix runtime PM imbalance on error

This userspace program includes UAPI headers exported to usr/include/.
'make headers' always works for the target architecture (i.e. the same
architecture as the kernel), so the sample program should be built for
the target as well. Kbuild now supports 'userprogs' for that.

I also guarded the CONFIG option by 'depends on CC_CAN_LINK' because
$(CC) may not provide libc.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

This reverts commit e0b250b5,
which broke build systems that need to install files to a certain
path, but do not set INSTALL_MOD_PATH when invoking 'make install'.

  $ make INSTALL_PATH=/tmp/destdir install
  mkdir: cannot create directory ‘/lib/modules/5.8.0-rc1+/’: Permission denied
  Makefile:1342: recipe for target '_builtin_inst_' failed
  make: *** [_builtin_inst_] Error 1

While modules.builtin is useful also for CONFIG_MODULES=n, this change
in the behavior is quite unexpected. Maybe "make modules_install"
can install modules.builtin irrespective of CONFIG_MODULES as Jonas
originally suggested.

Anyway, that commit should be reverted ASAP.
Reported-by: Douglas Anderson <dianders@chromium.org>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Cc: Jonas Karlman <jonas@kwiboo.se>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Guenter Roeck <linux@roeck-us.net>

Pull SCSI fixes from James Bottomley:
 "One minor fix and two patches reworking the ata dma drain for the
  !CONFIG_LIBATA case. The latter is a 5.7 regression fix"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: Wire up ata_scsi_dma_need_drain for SAS HBA drivers
  scsi: libata: Provide an ata_scsi_dma_need_drain stub for !CONFIG_ATA
  scsi: ufs-bsg: Fix runtime PM imbalance on error

Pull i2c fixes from Wolfram Sang:

 - a small collection of remaining API conversion patches (all acked)
   which allow to finally remove the deprecated API

 - some documentation fixes and a MAINTAINERS addition

* 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
  MAINTAINERS: Add robert and myself as qcom i2c cci maintainers
  i2c: smbus: Fix spelling mistake in the comments
  Documentation/i2c: SMBus start signal is S not A
  i2c: remove deprecated i2c_new_device API
  Documentation: media: convert to use i2c_new_client_device()
  video: backlight: tosa_lcd: convert to use i2c_new_client_device()
  x86/platform/intel-mid: convert to use i2c_new_client_device()
  drm: encoder_slave: use new I2C API
  drm: encoder_slave: fix refcouting error for modules