io_uring/unix: drop usage of io_uring socket

Since we no longer allow sending io_uring fds over SCM_RIGHTS, move to
using io_is_uring_fops() to detect whether this is a io_uring fd or not.
With that done, kill off io_uring_get_socket() as nobody calls it
anymore.

This is in preparation to yanking out the rest of the core related to
unix gc with io_uring.

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

io_uring: split out cmd api into a separate header

linux/io_uring.h is slowly becoming a rubbish bin where we put
anything exposed to other subsystems. For instance, the task exit
hooks and io_uring cmd infra are completely orthogonal and don't need
each other's definitions. Start cleaning it up by splitting out all
command bits into a new header file.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/7ec50bae6e21f371d3850796e716917fc141225a.1701391955.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring: remove uring_cmd cookie

No more users of this field.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20231130215309.2923568-5-kbusch@meta.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

iouring: remove IORING_URING_CMD_POLLED

No more users of this flag.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20231130215309.2923568-4-kbusch@meta.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring/cmd: Pass compat mode in issue_flags

Create a new flag to track if the operation is running compat mode.
This basically check the context->compat and pass it to the issue_flags,
so, it could be queried later in the callbacks.

Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Gabriel Krisman Bertazi <krisman@suse.de>
Link: https://lore.kernel.org/r/20231016134750.1381153-6-leitao@debian.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring: cancelable uring_cmd

uring_cmd may never complete, such as ublk, in which uring cmd isn't
completed until one new block request is coming from ublk block device.

Add cancelable uring_cmd to provide mechanism to driver for cancelling
pending commands in its own way.

Add API of io_uring_cmd_mark_cancelable() for driver to mark one command as
cancelable, then io_uring will cancel this command in
io_uring_cancel_generic(). ->uring_cmd() callback is reused for canceling
command in driver's way, then driver gets notified with the cancelling
from io_uring.

Add API of io_uring_cmd_get_task() to help driver cancel handler
deal with the canceling.

Reviewed-by: Gabriel Krisman Bertazi <krisman@suse.de>
Suggested-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring: retain top 8bits of uring_cmd flags for kernel internal use

Retain top 8bits of uring_cmd flags for kernel internal use, so that we
can move IORING_URING_CMD_POLLED out of uapi header.

Reviewed-by: Gabriel Krisman Bertazi <krisman@suse.de>
Reviewed-by: Anuj Gupta <anuj20.g@samsung.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring: Add io_uring command support for sockets

Enable io_uring commands on network sockets. Create two new
SOCKET_URING_OP commands that will operate on sockets.

In order to call ioctl on sockets, use the file_operations->io_uring_cmd
callbacks, and map it to a uring socket function, which handles the
SOCKET_URING_OP accordingly, and calls socket ioctls.

This patches was tested by creating a new test case in liburing.
Link: https://github.com/leitao/liburing/tree/io_uring_cmd

Signed-off-by: Breno Leitao <leitao@debian.org>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/r/20230627134424.2784797-1-leitao@debian.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring/cmd: add cmd lazy tw wake helper

We want to use IOU_F_TWQ_LAZY_WAKE in commands. First, introduce a new
cmd tw helper accepting TWQ flags, and then add
io_uring_cmd_do_in_task_laz() that will pass IOU_F_TWQ_LAZY_WAKE and
imply the "lazy" semantics, i.e. it posts no more than 1 CQE and
delaying execution of this tw should not prevent forward progress.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/5b9f6716006df7e817f18bd555aee2f8f9c8b0c3.1684154817.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring: make io_uring_sqe_cmd() unconditionally available

If CONFIG_IO_URING isn't set, then io_uring_sqe_cmd() is not defined.
As the nvme driver uses this helper, it causes a compilation issue:

drivers/nvme/host/ioctl.c: In function 'nvme_uring_cmd_io':
drivers/nvme/host/ioctl.c:555:44: error: implicit declaration of function 'io_uring_sqe_cmd'; did you mean 'io_uring_free'? [-Werror=implicit-function-declaration]
555 | const struct nvme_uring_cmd *cmd = io_uring_sqe_cmd(ioucmd->sqe);
| ^~~~~~~~~~~~~~~~
| io_uring_free

Fix it by just making io_uring_sqe_cmd() generally available - the types
are known, and there's no reason to hide it under CONFIG_IO_URING.

Fixes: fd9b8547bc5c ("io_uring: Pass whole sqe to commands")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Chen-Yu Tsai <wenst@chromium.org>
Tested-by: Chen-Yu Tsai <wenst@chromium.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring: Pass whole sqe to commands

Currently uring CMD operation relies on having large SQEs, but future
operations might want to use normal SQE.

The io_uring_cmd currently only saves the payload (cmd) part of the SQE,
but, for commands that use normal SQE size, it might be necessary to
access the initial SQE fields outside of the payload/cmd block. So,
saves the whole SQE other than just the pdu.

This changes slightly how the io_uring_cmd works, since the cmd
structures and callbacks are not opaque to io_uring anymore. I.e, the
callbacks can look at the SQE entries, not only, in the cmd structure.

The main advantage is that we don't need to create custom structures for
simple commands.

Creates io_uring_sqe_cmd() that returns the cmd private data as a null
pointer and avoids casting in the callee side.
Also, make most of ublk_drv's sqe->cmd priv structure into const, and use
io_uring_sqe_cmd() to get the private structure, removing the unwanted
cast. (There is one case where the cast is still needed since the
header->{len,addr} is updated in the private structure)

Suggested-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/20230504121856.904491-3-leitao@debian.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/io_uring: pass in issue_flags for uring_cmd task_work handling

io_uring_cmd_done() currently assumes that the uring_lock is held
when invoked, and while it generally is, this is not guaranteed.
Pass in the issue_flags associated with it, so that we have
IO_URING_F_UNLOCKED available to be able to lock the CQ ring
appropriately when completing events.

Cc: stable@vger.kernel.org
Fixes: ee692a21e9bf ("fs,io_uring: add infrastructure for uring-cmd")
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring: complete all requests in task context

This patch adds ctx->task_complete flag. If set, we'll complete all
requests in the context of the original task. Note, this extends to
completion CQE posting only but not io_kiocb cleanup / free, e.g. io-wq
may free the requests in the free calllback. This flag will be used
later for optimisations purposes.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/21ece72953f76bb2e77659a72a14326227ab6460.1670384893.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring: reshuffle issue_flags

Reshuffle issue flags to keep normal flags separate from the uring_cmd
ctx-setup like flags. Shift the second type to the second byte so it's
easier to add new ones in the future.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/d6e4696c883943082d248716f4cd568f37b17a74.1669821213.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring: fix multishot accept request leaks

Having REQ_F_POLLED set doesn't guarantee that the request is
executed as a multishot from the polling path. Fortunately for us, if
the code thinks it's multishot issue when it's not, it can only ask to
skip completion so leaking the request. Use issue_flags to mark
multipoll issues.

Cc: stable@vger.kernel.org
Fixes: 390ed29b5e425 ("io_uring: add IORING_ACCEPT_MULTISHOT for accept")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/7700ac57653f2823e30b34dc74da68678c0c5f13.1668710222.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring: Add missing inline to io_uring_cmd_import_fixed() dummy

If CONFIG_IO_URING is not set:

include/linux/io_uring.h:65:12: error: ‘io_uring_cmd_import_fixed’ defined but not used [-Werror=unused-function]
65 | static int io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw,
| ^~~~~~~~~~~~~~~~~~~~~~~~~

Fix this by adding the missing "inline" keyword.

Fixes: a9216fac3ed8819c ("io_uring: add io_uring_cmd_import_fixed")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/7404b4a696f64e33e5ef3c5bd3754d4f26d13e50.1664887093.git.geert+renesas@glider.be
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring: introduce fixed buffer support for io_uring_cmd

Add IORING_URING_CMD_FIXED flag that is to be used for sending io_uring
command with previously registered buffers. User-space passes the buffer
index in sqe->buf_index, same as done in read/write variants that uses
fixed buffers.

Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Link: https://lore.kernel.org/r/20220930062749.152261-3-anuj20.g@samsung.com
[axboe: shuffle valid flags check before acting on it]
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring: add io_uring_cmd_import_fixed

This is a new helper that callers can use to obtain a bvec iterator for
the previously mapped buffer. This is preparatory work to enable
fixed-buffer support for io_uring_cmd.

Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Link: https://lore.kernel.org/r/20220930062749.152261-2-anuj20.g@samsung.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring: add iopoll infrastructure for io_uring_cmd

Put this up in the same way as iopoll is done for regular read/write IO.
Make place for storing a cookie into struct io_uring_cmd on submission.
Perform the completion using the ->uring_cmd_iopoll handler.

Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
Link: https://lore.kernel.org/r/20220823161443.49436-3-joshi.k@samsung.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs,io_uring: add infrastructure for uring-cmd

file_operations->uring_cmd is a file private handler.
This is somewhat similar to ioctl but hopefully a lot more sane and
useful as it can be used to enable many io_uring capabilities for the
underlying operation.

IORING_OP_URING_CMD is a file private kind of request. io_uring doesn't
know what is in this command type, it's for the provider of ->uring_cmd()
to deal with.

Co-developed-by: Kanchan Joshi <joshi.k@samsung.com>
Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220511054750.20432-2-joshi.k@samsung.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring: add io_uring_get_opcode

In some debug scenarios it is useful to have the text representation of
the opcode. Add this function in preparation.

Signed-off-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220426082907.3600028-3-dylany@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring: add support for registering ring file descriptors

Lots of workloads use multiple threads, in which case the file table is
shared between them. This makes getting and putting the ring file
descriptor for each io_uring_enter(2) system call more expensive, as it
involves an atomic get and put for each call.

Similarly to how we allow registering normal file descriptors to avoid
this overhead, add support for an io_uring_register(2) API that allows
to register the ring fds themselves:

1) IORING_REGISTER_RING_FDS - takes an array of io_uring_rsrc_update
structs, and registers them with the task.
2) IORING_UNREGISTER_RING_FDS - takes an array of io_uring_src_update
structs, and unregisters them.

When a ring fd is registered, it is internally represented by an offset.
This offset is returned to the application, and the application then
uses this offset and sets IORING_ENTER_REGISTERED_RING for the
io_uring_enter(2) system call. This works just like using a registered
file descriptor, rather than a real one, in an SQE, where
IOSQE_FIXED_FILE gets set to tell io_uring that we're using an internal
offset/descriptor rather than a real file descriptor.

In initial testing, this provides a nice bump in performance for
threaded applications in real world cases where the batch count (eg
number of requests submitted per io_uring_enter(2) invocation) is low.
In a microbenchmark, submitting NOP requests, we see the following
increases in performance:

Requests per syscall Baseline Registered Increase
----------------------------------------------------------------
1 ~7030K ~8080K +15%
2 ~13120K ~14800K +13%
4 ~22740K ~25300K +11%

Co-developed-by: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring: remove files pointer in cancellation functions

When doing cancellation, we use a parameter to indicate where it's from
do_exit or exec. So a boolean value is good enough for this, remove the
struct files* as it is not necessary.

Signed-off-by: Hao Xu <haoxu@linux.alibaba.com>
[axboe: fixup io_uring_files_cancel for !CONFIG_IO_URING]
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring: extract io_uring_files_cancel() in io_uring_task_cancel()

Extract io_uring_files_cancel() call in io_uring_task_cancel() to make
io_uring_files_cancel() and io_uring_task_cancel() coherent and easy to
read.

Signed-off-by: Hao Xu <haoxu@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring: unify files and task cancel

Now __io_uring_cancel() and __io_uring_files_cancel() are very similar
and mostly differ by how we count requests, merge them and allow
tctx_inflight() to handle counting.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/1a5986a97df4dc1378f3fe0ca1eb483dbcf42112.1618101759.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring: remove structures from include/linux/io_uring.h

Link: https://lore.kernel.org/r/8c1d14f3748105f4caeda01716d47af2fa41d11c.1615809009.git.metze@samba.org
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring: index io_uring->xa by ctx not file

We don't use task file notes anymore, and no need left in indexing
task->io_uring->xa by file, and replace it with ctx. It's better
design-wise, especially since we keep a dangling file, and so have to
keep an eye on not dereferencing it.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring: destroy io-wq on exec

Destroy current's io-wq backend and tctx on __io_uring_task_cancel(),
aka exec(). Looks it's not strictly necessary, because it will be done
at some point when the task dies and changes of creds/files/etc. are
handled, but better to do that earlier to free io-wq and not potentially
lock previous mm and other resources for the time being.

It's safe to do because we wait for all requests of the current task to
complete, so no request will use tctx afterwards. Note, that
io_uring_files_cancel() may leave some requests for later reaping, so it
leaves tctx intact, that's ok as the task is dying anyway.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring: ensure io-wq context is always destroyed for tasks

If the task ends up doing no IO, the context list is empty and we don't
call into __io_uring_files_cancel() when the task exits. This can cause
a leak of the io-wq structures.

Ensure we always call __io_uring_files_cancel(), even if the task
context list is empty.

Fixes: 5aa75ed5b93f ("io_uring: tie async worker side to the task context")
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring: remove io_identity

We are no longer grabbing state, so no need to maintain an IO identity
that we COW if there are changes.

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

io_uring: tie async worker side to the task context

Move it outside of the io_ring_ctx, and tie it to the io_uring task
context.

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

io_uring: provide FIFO ordering for task_work

task_work is a LIFO list, due to how it's implemented as a lockless
list. For long chains of task_work, this can be problematic as the
first entry added is the last one processed. Similarly, we'd waste
a lot of CPU cycles reversing this list.

Wrap the task_work so we have a single task_work entry per task per
ctx, and use that to run it in the right order.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring: properly handle SQPOLL request cancelations

Track if a given task io_uring context contains SQPOLL instances, so we
can iterate those for cancelation (and request counts). This ensures that
we properly wait on SQPOLL contexts, and find everything that needs
canceling.

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

io-wq: inherit audit loginuid and sessionid

Make sure the async io-wq workers inherit the loginuid and sessionid from
the original task, and restore them to unset once we're done with the
async work item.

While at it, disable the ability for kernel threads to write to their own
loginuid.

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

io_uring: use percpu counters to track inflight requests

Even though we place the req_issued and req_complete in separate
cachelines, there's considerable overhead in doing the atomics
particularly on the completion side.

Get rid of having the two counters, and just use a percpu_counter for
this. That's what it was made for, after all. This considerably
reduces the overhead in __io_free_req().

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

io_uring: assign new io_identity for task if members have changed

This avoids doing a copy for each new async IO, if some parts of the
io_identity has changed. We avoid reference counting for the normal
fast path of nothing ever changing.

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

io_uring: store io_identity in io_uring_task

This is, by definition, a per-task structure. So store it in the
task context, instead of doing carrying it in each io_kiocb. We're being
a bit inefficient if members have changed, as that requires an alloc and
copy of a new io_identity struct. The next patch will fix that up.

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

io_uring: COW io_identity on mismatch

If the io_identity doesn't completely match the task, then create a
copy of it and use that. The existing copy remains valid until the last
user of it has gone away.

This also changes the personality lookup to be indexed by io_identity,
instead of creds directly.

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

io_uring: move io identity items into separate struct

io-wq contains a pointer to the identity, which we just hold in io_kiocb
for now. This is in preparation for putting this outside io_kiocb. The
only exception is struct files_struct, which we'll need different rules
for to avoid a circular dependency.

No functional changes in this patch.

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

io_uring: move io_uring_get_socket() into io_uring.h

Now we have a io_uring kernel header, move this definition out of fs.h
and into io_uring.h where it belongs.

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

io_uring: don't rely on weak ->files references

Grab actual references to the files_struct. To avoid circular references
issues due to this, we add a per-task note that keeps track of what
io_uring contexts a task has used. When the tasks execs or exits its
assigned files, we cancel requests based on this tracking.

With that, we can grab proper references to the files table, and no
longer need to rely on stashing away ring_fd and ring_file to check
if the ring_fd may have been closed.

Cc: stable@vger.kernel.org # v5.5+
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>