Move setting ctx->drain_next to the only place it could be set, when it
got linked non-head requests. The same for checking it, it's interesting
only for a head of a link or a non-linked request.

No functional changes here. This removes some code from the common path
and also removes REQ_F_DRAIN_LINK flag, as it doesn't need it anymore.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

The application currently has no way of knowing if a given opcode is
supported or not without having to try and issue one and see if we get
-EINVAL or not. And even this approach is fraught with peril, as maybe
we're getting -EINVAL due to some fields being missing, or maybe it's
just not that easy to issue that particular command without doing some
other leg work in terms of setup first.

This adds IORING_REGISTER_PROBE, which fills in a structure with info
on what it supported or not. This will work even with sparse opcode
fields, which may happen in the future or even today if someone
backports specific features to older kernels.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We can't assume that the whole batch has fixed files in it. If it's a
mix, or none at all, then we can end up doing a ref put that either
messes up accounting, or causes an oops if we have no fixed files at
all.

Also ensure we free requests properly between inflight accounted and
normal requests.

Fixes: 82c721577011 ("io_uring: extend batch freeing to cover more cases")
Reported-by: NDmitrii Dolgov <9erthalion6@gmail.com>
Reported-by: NPavel Begunkov <asml.silence@gmail.com>
Tested-by: NDmitrii Dolgov <9erthalion6@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

For some test apps at least, user_data is just zeroes. So it's not a
good way to tell what the command actually is. Add the opcode to the
issue trace point.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Add support for the new openat2(2) system call. It's trivial to do, as
we can have openat(2) just be wrapped around it.
Suggested-by: NStefan Metzmacher <metze@samba.org>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We only use it internally in the prep functions for both statx and
openat, so we don't need it to be persistent across the request.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We'll need this for openat2(2) support, remove flags and mode from
the existing io_open struct.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

If an application is using eventfd notifications with poll to know when
new SQEs can be issued, it's expecting the following read/writes to
complete inline. And with that, it knows that there are events available,
and don't want spurious wakeups on the eventfd for those requests.

This adds IORING_REGISTER_EVENTFD_ASYNC, which works just like
IORING_REGISTER_EVENTFD, except it only triggers notifications for events
that happen from async completions (IRQ, or io-wq worker completions).
Any completions inline from the submission itself will not trigger
notifications.
Suggested-by: NMark Papadakis <markuspapadakis@icloud.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

In preparation for adding another one, which would make us spill into
another long (and hence bump the size of the ctx), change them to
bit fields.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

If an application attempts to register a set with unbounded requests
pending, we can be stuck here forever if they don't complete. We can
make this wait interruptible, and just abort if we get signaled.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Null check kfree is redundant, so remove it.
This is detected by coccinelle.
Signed-off-by: NYueHaibing <yuehaibing@huawei.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This adds IORING_OP_SEND for send(2) support, and IORING_OP_RECV for
recv(2) support.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

io_wq workers use io_issue_sqe() to forward sqes and never
io_queue_sqe(). Remove extra check for io_wq_current_is_worker()
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

It should be pretty rare to not submitting anything when there is
something in the ring. No need to keep heuristics for this case.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

A user may ask to submit more than there is in the ring, and then
io_uring will submit as much as it can. However, in the last iteration
it will allocate an io_kiocb and immediately free it. It could do
better and adjust @to_submit to what is in the ring.

And since the ring's head is already checked here, there is no need to
do it in the loop, spamming with smp_load_acquire()'s barriers
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Make io_submit_sqes() to clamp @to_submit itself. It removes duplicated
code and prepares for following changes.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Some applications like to start small in terms of ring size, and then
ramp up as needed. This is a bit tricky to do currently, since we don't
advertise the max ring size.

This adds IORING_SETUP_CLAMP. If set, and the values for SQ or CQ ring
size exceed what we support, then clamp them at the max values instead
of returning -EINVAL. Since we return the chosen ring sizes after setup,
no further changes are needed on the application side. io_uring already
changes the ring sizes if the application doesn't ask for power-of-two
sizes, for example.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Currently we only batch free if fixed files are used, no links, no aux
data, etc. This extends the batch freeing to only exclude the linked
case and fallback case, and make io_free_req_many() handle the other
cases just fine.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This cleans up the code a bit, and it allows us to build on top of the
multi-req freeing.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

percpu_ref_tryget() has its own overhead. Instead getting a reference
for each request, grab a bunch once per io_submit_sqes().

~5% throughput boost for a "submit and wait 128 nops" benchmark.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>

__io_req_free_empty() -> __io_req_do_free()
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This adds support for doing madvise(2) through io_uring. We assume that
any operation can block, and hence punt everything async. This could be
improved, but hard to make bullet proof. The async punt ensures it's
safe.
Reviewed-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This adds support for doing fadvise through io_uring. We assume that
WILLNEED doesn't block, but that DONTNEED may block.
Reviewed-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This behaves like preadv2/pwritev2 with offset == -1, it'll use (and
update) the current file position. This obviously comes with the caveat
that if the application has multiple read/writes in flight, then the
end result will not be as expected. This is similar to threads sharing
a file descriptor and doing IO using the current file position.

Since this feature isn't easily detectable by doing a read or write,
add a feature flags, IORING_FEAT_RW_CUR_POS, to allow applications to
detect presence of this feature.
Reported-by: N李通洲 <carter.li@eoitek.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

For uses cases that don't already naturally have an iovec, it's easier
(or more convenient) to just use a buffer address + length. This is
particular true if the use case is from languages that want to create
a memory safe abstraction on top of io_uring, and where introducing
the need for the iovec may impose an ownership issue. For those cases,
they currently need an indirection buffer, which means allocating data
just for this purpose.

Add basic read/write that don't require the iovec.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

For busy IORING_OP_POLL_ADD workloads, we can have enough contention
on the completion lock that we fail the inline completion path quite
often as we fail the trylock on that lock. Add a list for deferred
completions that we can use in that case. This helps reduce the number
of async offloads we have to do, as if we get multiple completions in
a row, we'll piggy back on to the poll_llist instead of having to queue
our own offload.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We currently check ->cq_overflow_list from both SQ and CQ context, which
causes some bouncing of that cache line. Add separate bits of state for
this instead, so that the SQ side can check using its own state, and
likewise for the CQ side.

This adds ->sq_check_overflow with the SQ state, and ->cq_check_overflow
with the CQ state. If we hit an overflow condition, both of these bits
are set. Likewise for overflow flush clear, we clear both bits. For the
fast path of just checking if there's an overflow condition on either
the SQ or CQ side, we can use our own private bit for this.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We currently have various switch statements that check if an opcode needs
a file, mm, etc. These are hard to keep in sync as opcodes are added. Add
a struct io_op_def that holds all of this information, so we have just
one spot to update when opcodes are added.

This also enables us to NOT allocate req->io if a deferred command
doesn't need it, and corrects some mistakes we had in terms of what
commands need mm context.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

__io_free_req() and io_double_put_req() aren't used before they are
defined, so we can kill these two forwards.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Move io_queue_link_head() to links handling code in io_submit_sqe(),
so it wouldn't need extra checks and would have better data locality.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Calling "prev" a head of a link is a bit misleading. Rename it
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

io_uring defaults to always doing inline submissions, if at all
possible. But for larger copies, even if the data is fully cached, that
can take a long time. Add an IOSQE_ASYNC flag that the application can
set on the SQE - if set, it'll ensure that we always go async for those
kinds of requests. Use the io-wq IO_WQ_WORK_CONCURRENT flag to ensure we
get the concurrency we desire for this case.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This provides support for async statx(2) through io_uring.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We currently fully quiesce the ring before an unregister or update of
the fixed fileset. This is very expensive, and we can be a bit smarter
about this.

Add a percpu refcount for the file tables as a whole. Grab a percpu ref
when we use a registered file, and put it on completion. This is cheap
to do. Upon removal of a file from a set, switch the ref count to atomic
mode. When we hit zero ref on the completion side, then we know we can
drop the previously registered files. When the old files have been
dropped, switch the ref back to percpu mode for normal operation.

Since there's a period between doing the update and the kernel being
done with it, add a IORING_OP_FILES_UPDATE opcode that can perform the
same action. The application knows the update has completed when it gets
the CQE for it. Between doing the update and receiving this completion,
the application must continue to use the unregistered fd if submitting
IO on this particular file.

This takes the runtime of test/file-register from liburing from 14s to
about 0.7s.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This works just like close(2), unsurprisingly. We remove the file
descriptor and post the completion inline, then offload the actual
(potential) last file put to async context.

Mark the async part of this work as uncancellable, as we really must
guarantee that the latter part of the close is run.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Not all work can be cancelled, some of it we may need to guarantee
that it runs to completion. Allow the caller to set IO_WQ_WORK_NO_CANCEL
on work that must not be cancelled. Note that the caller work function
must also check for IO_WQ_WORK_NO_CANCEL on work that is marked
IO_WQ_WORK_CANCEL.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This works just like openat(2), except it can be performed async. For
the normal case of a non-blocking path lookup this will complete
inline. If we have to do IO to perform the open, it'll be done from
async context.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This exposes fallocate(2) through io_uring.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

fds field of struct io_uring_files_update is problematic with regards
to compat user space, as pointer size is different in 32-bit, 32-on-64-bit,
and 64-bit user space.  In order to avoid custom handling of compat in
the syscall implementation, make fds __u64 and use u64_to_user_ptr in
order to retrieve it.  Also, align the field naturally and check that
no garbage is passed there.

Fixes: c3a31e60 ("io_uring: add support for IORING_REGISTER_FILES_UPDATE")
Signed-off-by: NEugene Syromiatnikov <esyr@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

If the credentials or the mm doesn't match, don't allow the task to
submit anything on behalf of this ring. The task that owns the ring can
pass the file descriptor to another task, but we don't want to allow
that task to submit an SQE that then assumes the ring mm and creds if
it needs to go async.

Cc: stable@vger.kernel.org
Suggested-by: NStefan Metzmacher <metze@samba.org>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

A previous commit moved the locking for the async sqthread, but didn't
take into account that the io-wq workers still need it. We can't use
req->in_async for this anymore as both the sqthread and io-wq workers
set it, gate the need for locking on io_wq_current_is_worker() instead.

Fixes: 8a4955ff ("io_uring: sqthread should grab ctx->uring_lock for submissions")
Reported-by: NBijan Mottahedeh <bijan.mottahedeh@oracle.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>