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: NJens 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: NJonathan Lemon <jonathan.lemon@gmail.com>
Signed-off-by: NJens 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: NJens 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: NJens 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: NJens 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: NJens 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: NJens 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: NJens 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: NJens 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: NJens 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: NJens 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: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens 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: NJens 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: NJens 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: NJens 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: NJens 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: NJens 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: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens 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: NJens 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: NJens 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: NJens 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: N李通洲 <carter.li@eoitek.com>
Signed-off-by: NJens 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: NBrian Gianforcaro <b.gianfo@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

If we submit an unknown opcode and have fd == -1, io_op_needs_file()
will return true as we default to needing a file. Then when we go and
assign the file, we find the 'fd' invalid and return -EBADF. We really
should be returning -EINVAL for that case, as we normally do for
unsupported opcodes.

Change io_op_needs_file() to have the following return values:

0   - does not need a file
1   - does need a file
< 0 - error value

and use this to pass back the right value for this invalid case.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

In chasing a performance issue between using IORING_OP_RECVMSG and
IORING_OP_READV on sockets, tracing showed that we always punt the
socket reads to async offload. This is due to io_file_supports_async()
not checking for S_ISSOCK on the inode. Since sockets supports the
O_NONBLOCK (or MSG_DONTWAIT) flag just fine, add sockets to the list
of file types that we can do a non-blocking issue to.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We hash regular files to avoid having multiple threads hammer on the
inode mutex, but it should not be needed on other types of files
(like sockets).
Signed-off-by: NJens Axboe <axboe@kernel.dk>

One major use case of linked commands is the ability to run the next
link inline, if at all possible. This is done correctly for async
offload, but somewhere along the line we lost the ability to do so when
we were able to complete a request without having to punt it. Ensure
that we do so correctly.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This essentially reverts commit e944475e. For high poll ops
workloads, like TAO, the dynamic allocation of the wait_queue
entry for IORING_OP_POLL_ADD adds considerable extra overhead.
Go back to embedding the wait_queue_entry, but keep the usage of
wait->private for the pointer stashing.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Don't just assign it from the main call path, that can miss the case
when we're called from issue deferral.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We use the mutex to guard against registered file updates, for instance.
Ensure we're safe in accessing that state against concurrent updates.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Some commands will invariably end in a failure in the sense that the
completion result will be less than zero. One such example is timeouts
that don't have a completion count set, they will always complete with
-ETIME unless cancelled.

For linked commands, we sever links and fail the rest of the chain if
the result is less than zero. Since we have commands where we know that
will happen, add IOSQE_IO_HARDLINK as a stronger link that doesn't sever
regardless of the completion result. Note that the link will still sever
if we fail submitting the parent request, hard links are only resilient
in the presence of completion results for requests that did submit
correctly.

Cc: stable@vger.kernel.org # v5.4
Reviewed-by: NPavel Begunkov <asml.silence@gmail.com>
Reported-by: N李通洲 <carter.li@eoitek.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

thatn -> than.
Signed-off-by: NLiming Wu <19092205@suning.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Links are created by chaining requests through req->list with an
exception that head uses req->link_list. (e.g. link_list->list->list)
Because of that, io_req_link_next() needs complex splicing to advance.

Link them all through list_list. Also, it seems to be simpler and more
consistent IMHO.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

In case of an error io_submit_sqe() drops a request and continues
without it, even if the request was a part of a link. Not only it
doesn't cancel links, but also may execute wrong sequence of actions.

Stop consuming sqes, and let the user handle errors.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We recently changed this from a single list to an rbtree, but for some
real life workloads, the rbtree slows down the submission/insertion
case enough so that it's the top cycle consumer on the io_uring side.
In testing, using a hash table is a more well rounded compromise. It
is fast for insertion, and as long as it's sized appropriately, it
works well for the cancellation case as well. Running TAO with a lot
of network sockets, this removes io_poll_req_insert() from spending
2% of the CPU cycles.
Reported-by: NDan Melnic <dmm@fb.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

If we defer a timeout, we should ensure that we copy the timespec
when we have consumed the sqe. This is similar to commit f67676d1
for read/write requests. We already did this correctly for timeouts
deferred as links, but do it generally and use the infrastructure added
by commit 1a6b74fc instead of having the timeout deferral use its
own.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

There's really no reason why we forbid things like link/drain etc on
regular timeout commands. Enable the usual SQE flags on timeouts.
Reported-by: N李通洲 <carter.li@eoitek.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Right now we return it to userspace, which means the application has
to poll for the socket to be writeable. Let's just treat it like
-EAGAIN and have io_uring handle it internally, this makes it much
easier to use.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Parameter ctx we have never used, clean it up.
Signed-off-by: NJackie Liu <liuyun01@kylinos.cn>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

If this flag is set, applications can be certain that any data for
async offload has been consumed when the kernel has consumed the
SQE.
Signed-off-by: NJens Axboe <axboe@kernel.dk>