If an opcode doesn't support polling, just let it be executed
synchronously in iowq, otherwise it will do a nonblock attempt just to
fail in io_arm_poll_handler() and return back to blocking execution.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/6401256db01b88f448f15fcd241439cb76f5b940.1634987320.git.asml.silence@gmail.comReviewed-by: NHao Xu <haoxu@linux.alibaba.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

->pollout or ->pollin are set only for opcodes that need a file, so if
io_arm_poll_handler() tests them first we can be sure that the request
has file set and the ->file check can be removed.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/9adfe4f543d984875e516fce6da35348aab48668.1634987320.git.asml.silence@gmail.comReviewed-by: NHao Xu <haoxu@linux.alibaba.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

If we've got IO_WQ_WORK_CANCEL in io_wq_submit_work(), handle the error
on the same lines as the check instead of having a weird code flow. The
main loop doesn't change but goes one indention left.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/ff4a09cf41f7a22bbb294b6f1faea721e21fe615.1634987320.git.asml.silence@gmail.comReviewed-by: NHao Xu <haoxu@linux.alibaba.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Do a bit of cleaning for the main loop of io_wq_submit_work(). Get rid
of switch, just replace it with a single if as we're retrying in both
other cases. Kill issue_sqe label, Get rid of needs_poll nesting and
disambiguate a bit the comment.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/ed12ce0c64e051f9a6b8a37a24f8ea554d299c29.1634987320.git.asml.silence@gmail.comReviewed-by: NHao Xu <haoxu@linux.alibaba.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Use io_worker_release() instead of hand coding it in io_worker_exit().
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/6f95f09d2cdbafcbb2e22ad0d1a2bc4d3962bf65.1634987320.git.asml.silence@gmail.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

The current logic of requests with IOSQE_ASYNC is first queueing it to
io-worker, then execute it in a synchronous way. For unbound works like
pollable requests(e.g. read/write a socketfd), the io-worker may stuck
there waiting for events for a long time. And thus other works wait in
the list for a long time too.
Let's introduce a new way for unbound works (currently pollable
requests), with this a request will first be queued to io-worker, then
executed in a nonblock try rather than a synchronous way. Failure of
that leads it to arm poll stuff and then the worker can begin to handle
other works.
The detail process of this kind of requests is:

step1: original context:
           queue it to io-worker
step2: io-worker context:
           nonblock try(the old logic is a synchronous try here)
               |
               |--fail--> arm poll
                            |
                            |--(fail/ready)-->synchronous issue
                            |
                            |--(succeed)-->worker finish it's job, tw
                                           take over the req

This works much better than the old IOSQE_ASYNC logic in cases where
unbound max_worker is relatively small. In this case, number of
io-worker eazily increments to max_worker, new worker cannot be created
and running workers stuck there handling old works in IOSQE_ASYNC mode.

In my 64-core machine, set unbound max_worker to 20, run echo-server,
turns out:
(arguments: register_file, connetion number is 1000, message size is 12
Byte)
original IOSQE_ASYNC: 76664.151 tps
after this patch: 166934.985 tps
Suggested-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NHao Xu <haoxu@linux.alibaba.com>
Link: https://lore.kernel.org/r/20211018133445.103438-1-haoxu@linux.alibaba.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

Use ERR_CAST() instead of ERR_PTR(PTR_ERR()).
This makes it more readable and also fix this warning detected by
err_cast.cocci:
./fs/io_uring.c: WARNING: 3208: 11-18: ERR_CAST can be used with buf
Reported-by: NZeal Robot <zealci@zte.com.cn>
Signed-off-by: NChangcheng Deng <deng.changcheng@zte.com.cn>
Link: https://lore.kernel.org/r/20211020084948.1038420-1-deng.changcheng@zte.com.cnSigned-off-by: NJens Axboe <axboe@kernel.dk>

Currently force_nonblock stands for three meanings:
 - nowait or not
 - in an io-worker or not(hold uring_lock or not)

Let's split the logic to two flags, IO_URING_F_NONBLOCK and
IO_URING_F_UNLOCKED for convenience of the next patch.
Suggested-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NHao Xu <haoxu@linux.alibaba.com>
Reviewed-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/20211018133431.103298-1-haoxu@linux.alibaba.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

When enabling -Wunused warnings by building with W=1, I get an
instance of the -Wunused-but-set-parameter warning in the io_uring code:

fs/io_uring.c: In function 'io_queue_async_work':
fs/io_uring.c:1445:61: error: parameter 'locked' set but not used [-Werror=unused-but-set-parameter]
 1445 | static void io_queue_async_work(struct io_kiocb *req, bool *locked)
      |                                                       ~~~~~~^~~~~~

There are very few warnings of this type, so it would be nice to enable
this by default and fix all the existing instances. As the assignment
serves no purpose by itself other than to prevent developers from using
the variable, an easy workaround is to remove the assignment and just
rename the argument to "dont_use".

Fixes: f237c30a ("io_uring: batch task work locking")
Link: https://lore.kernel.org/lkml/20210920121352.93063-1-arnd@kernel.org/Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20211019153507.348480-1-arnd@kernel.orgSigned-off-by: NJens Axboe <axboe@kernel.dk>

The block layer can use this knowledge to make smarter decisions on
how to handle the request, if it knows that N more may be coming. Switch
to using blk_start_plug_nr_ios() to pass in that information.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Make sure that REQ_F_SUPPORT_NOWAIT is always set io_prep_rw(), and so
we can stop caring about setting it down the line simplifying
io_file_supports_nowait().
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/60c8f1f5e2cb45e00f4897b2cec10c5b3669da91.1634425438.git.asml.silence@gmail.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

Merge REQ_F_NOWAIT_READ and REQ_F_NOWAIT_WRITE into one flag, i.e.
REQ_F_SUPPORT_NOWAIT. First it gets rid of dependence on CONFIG_64BIT
but also simplifies the code.

One thing to consider is when we don't have ->{read,write}_iter and go
through loop_rw_iter(). Just fail it with -EAGAIN if we expect nowait
behaviour but not sure whether it supports it.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/f832a20e5186c2e79c6519280c238f559a1d2bbc.1634425438.git.asml.silence@gmail.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

Don't check if we can do nowait before arming apoll, there are several
reasons for that. First, we don't care much about files that don't
support nowait. Second, it may be useful -- we don't want to be taking
away extra workers from io-wq when it can go in some async. Even if it
will go through io-wq eventually, it make difference in the numbers of
workers actually used. And the last one, it's needed to clean nowait in
future commits.

[kernel test robot: fix unused-var]
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/9d06f3cb2c8b686d970269a87986f154edb83043.1634425438.git.asml.silence@gmail.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

This commit reorders the conditions in a branch in io_write. The
reorder to check 'ret2 == -EAGAIN' first as checking
'(req->ctx->flags & IORING_SETUP_IOPOLL)' will likely be more
expensive due to 2x memory derefences.
Signed-off-by: NNoah Goldstein <goldstein.w.n@gmail.com>
Link: https://lore.kernel.org/r/20211017013229.4124279-1-goldstein.w.n@gmail.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

We already store req->file in a variable in io_prep_rw(), just use it
instead of a couple of left references to kicob->ki_filp.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/2f5889fc7ab670daefd5ccaedd99416d8355f0ad.1634314022.git.asml.silence@gmail.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

Move fixed rw io_req_set_rsrc_node() from rw prep into
io_import_fixed(), if we're using fixed buffers it will always be called
during submission as we save the state in advance,
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/68c06f66d5aa9661f1e4b88d08c52d23528297ec.1634314022.git.asml.silence@gmail.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

We pass iovec** into __io_import_iovec(), which should keep it,
initialise and modify accordingly. It's expensive, return it directly
from __io_import_iovec encoding errors with ERR_PTR if needed.

io_import_iovec keeps the old interface, but it's inline and so
everything is optimised nicely.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/6230e9769982f03a8f86fa58df24666088c44d3e.1634314022.git.asml.silence@gmail.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

Delay loading req->rw.{addr,len} in io_import_iovec until it's really
needed, so removing extra loads for the fixed path, which doesn't use
them.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/3cc48dd0c4f1a37c4ce9aab5784281a2d83ad8be.1634314022.git.asml.silence@gmail.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

Don't decide about locking based on io_wq_current_is_worker(), it's not
consistent with all other code and is expensive, use issue_flags.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/7546d5a58efa4360173541c6fe02ee6b8c7b4ea7.1634314022.git.asml.silence@gmail.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

Don't load req->ctx in advance, it takes an extra register and the field
stays valid even after opcode handlers. It also optimises out req->ctx
load in io_iopoll_req_issued() once it's inlined.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/1e45ff671c44be0eb904f2e448a211734893fa0b.1634314022.git.asml.silence@gmail.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

Combine force_nonblock branches (which is already optimised by
compiler), flip branches so the most hot/common path is the first, e.g.
as with non on-stack iov setup, and add extra likely/unlikely
attributions for errror paths.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/2c2536c5896d70994de76e387ea09a0402173a3f.1634144845.git.asml.silence@gmail.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

Make io_import_iovec taking struct io_rw_state instead of an iter
pointer. First it takes care of initialising iovec pointer, which can be
forgotten. Even more, we can not init it if not needed, e.g. in case of
IORING_OP_READ_FIXED or IORING_OP_READ. Also hide saving iter_state
inside of it by splitting out an inline function of it to avoid extra
ifs.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/b1bbc213a95e5272d4da5867bb977d9acb6f2109.1634144845.git.asml.silence@gmail.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

First, change IO_URING_F_NONBLOCK to take sign bit of the int, so
checking for it can be turned into test + sign-based-jump, makes the
binary smaller and may be faster.

Then, instead of passing need_lock boolean into io_import_iovec() just
give it issue_flags, which is already stored somewhere. Saves some space
on stack, a couple of test + cmov operations and other conversions.

note: we still leave
force_nonblock = issue_flags & IO_URING_F_NONBLOCK
variable, but it's optimised out by the compiler into testing
issue_flags directly.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/ee96547e692f6c975c229cd82fc721679571a734.1634144845.git.asml.silence@gmail.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

Currently io_read() and io_write() keep separate pointers to an iter and
to struct iov_iter_state, which is not great for register spilling and
requires more on-stack copies. They are both either on-stack or in
req->async_data at the same time, so use struct io_rw_state and keep a
pointer only to it, so having all the state with just one pointer.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/5c5e7ffd7dc25fc35075c70411ba99df72f237fa.1634144845.git.asml.silence@gmail.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

Add a new struct io_rw_state storing all iov related bits: fast iov,
iterator and iterator state. Not much changes here, simply convert
struct io_async_rw to use it.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/e8245ffcb568b228a009ec1eb79c993c813679f1.1634144845.git.asml.silence@gmail.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

Don't override req->result in io_complete_rw_iopoll() when it's already
of the same value, we have an if just above it, so move the assignment
there. Also, add one simle unlikely() in __io_complete_rw_common().
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/8dfeb4f84026a20172bcf82c05010abe955874ae.1634144845.git.asml.silence@gmail.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

Rearrange io_read return handling so first we expect it completing
successfully and only then checking for errors, which is a colder path.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/c91c7c2da11815ec8b04b5d872f60dc4cde662c5.1634144845.git.asml.silence@gmail.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

Some of the functions keep issue_flags as int, change those to unsigned.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/04ad43797783bc9cc7567f287ab545518f8e8cf2.1634144845.git.asml.silence@gmail.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

Apparently, percpu_ref_put/get() are expensive enough if done per
request, get them in a batch and cache on the submission side to avoid
getting it over and over again. Also, if we're completing under
uring_lock, return refs back into the cache instead of
perfcpu_ref_put(). Pretty similar to how we do tctx->cached_refs
accounting, but fall back to normal putting when we already changed a
rsrc node by the time of free.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/b40d8c5bc77d3c9550df8a319117a374ac85f8f4.1633817310.git.asml.silence@gmail.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

io_req_set_rsrc_node() reloads loads req->ctx, however it's already in
registers in all use cases, so better to pass it as a parameter.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/67a25557b8a51e90bfd578447a6f1671911b05ae.1633817310.git.asml.silence@gmail.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

[  158.514382] WARNING: CPU: 5 PID: 15251 at fs/io_uring.c:1141 io_free_batch_list+0x269/0x360
[  158.514426] RIP: 0010:io_free_batch_list+0x269/0x360
[  158.514437] Call Trace:
[  158.514440]  __io_submit_flush_completions+0xde/0x180
[  158.514444]  tctx_task_work+0x14a/0x220
[  158.514447]  task_work_run+0x64/0xa0
[  158.514448]  __do_sys_io_uring_enter+0x7c/0x970
[  158.514450]  __x64_sys_io_uring_enter+0x22/0x30
[  158.514451]  do_syscall_64+0x43/0x90
[  158.514453]  entry_SYSCALL_64_after_hwframe+0x44/0xae

We should not touch request internals including req->comp_list.next
after putting our ref if it's not final, e.g. we can start freeing
requests from the free cache.

Fixed: 62ca9cb93e7f8 ("io_uring: optimise io_free_batch_list()")
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/b1f4df38fbb8f111f52911a02fd418d0283a4e6f.1634047298.git.asml.silence@gmail.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

task_work_add() takes care of waking up the thread, remove useless
wake_up_process().
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/de9a71ee255112dcaed3b5d426be24934e74722c.1633532552.git.asml.silence@gmail.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

Looking at the assembly, the compiler decided to reload req->opcode in
io_op_defs[opcode].needs_file instead of one it had in a register, so
store it in a temp variable so it can be optimised out. Also move the
personality block later, it's better for spilling/etc. as it only
depends on @sqe, which we're keeping anyway.

By the way, zero req->opcode if it over IORING_OP_LAST, not a problem,
at the moment but is safer.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/6ba869f5f8b7b0f991c87fdf089f0abf87cbe06b.1633532552.git.asml.silence@gmail.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

struct io_submit_state's ->free_list and ->link are hotter and smaller
than ->plug, place them first.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/6ad3c15849f50b27ad012c042c73e6e069d22df7.1633532552.git.asml.silence@gmail.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

Add extra wq flushing for fallback_work, that's not necessary but safer
if invariants of io_fallback_req_func() change.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/24179419d6748516299600bc914f50b9e0b02275.1633532552.git.asml.silence@gmail.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

Plugging is only needed with requests that also need a file, so hide
plugging under a ->needs_file check. Also, place ->needs_file and ->plug
bits into the same byte of io_op_defs, it may matter for compilers, e.g.
only with the change a tested one decided to optimise two memory testb
into a more with two register testb.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/1600d1287bb7d16451d4ef3343252787a5314927.1633532552.git.asml.silence@gmail.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

CQE result is a 32-bit integer, so the functions generating CQEs are
better to accept not long but ints. Convert io_cqring_fill_event() and
other helpers.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/7ca6f15255e9117eae28adcac272744cae29b113.1633373302.git.asml.silence@gmail.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

Inline io_poll_complete(), it's simple and doesn't have any particular
purpose.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/933d7ee3e4450749a2d892235462c8f18d030293.1633373302.git.asml.silence@gmail.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

There is only a single user of io_req_needs_clean() inline it.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/6111d0221ef4b439cad401e135dd6a5f990a0501.1633373302.git.asml.silence@gmail.comSigned-off-by: NJens Axboe <axboe@kernel.dk>

We keep struct io_completion only as a temporal storage of cflags, Place
it in io_kiocb, it's cleaner, removes extra bits and even might be used
for future optimisations.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/5299bd5c223204065464bd87a515d0e405316086.1633373302.git.asml.silence@gmail.comSigned-off-by: NJens Axboe <axboe@kernel.dk>