RLIMIT_SIZE in needed only for execution from an io-wq context, hence
move all preparations from hot path to io-wq work setup.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

It's easier to return next work from ->do_work() than
having an in-out argument. Looks nicer and easier to compile.
Also, merge io_wq_assign_next() into its only user.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Renumerate IO_WQ flags, so they take adjacent bits
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

For an exiting process it tries to cancel all its inflight requests. Use
req->task to match such instead of work.pid. We always have req->task
set, and it will be valid because we're matching only current exiting
task.

Also, remove work.pid and everything related, it's useless now.
Reported-by: NEric W. Biederman <ebiederm@xmission.com>
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

If a process is going away, io_uring_flush() will cancel only 1
request with a matching pid. Cancel all of them
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This adds support for cancelling all io-wq works matching a predicate.
It isn't used yet, so no change in observable behaviour.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

If requests can be submitted and completed inline, we don't need to
initialize whole io_wq_work in io_init_req(), which is an expensive
operation, add a new 'REQ_F_WORK_INITIALIZED' to determine whether
io_wq_work is initialized and add a helper io_req_init_async(), users
must call io_req_init_async() for the first time touching any members
of io_wq_work.

I use /dev/nullb0 to evaluate performance improvement in my physical
machine:
  modprobe null_blk nr_devices=1 completion_nsec=0
  sudo taskset -c 60 fio  -name=fiotest -filename=/dev/nullb0 -iodepth=128
  -thread -rw=read -ioengine=io_uring -direct=1 -bs=4k -size=100G -numjobs=1
  -time_based -runtime=120

before this patch:
Run status group 0 (all jobs):
   READ: bw=724MiB/s (759MB/s), 724MiB/s-724MiB/s (759MB/s-759MB/s),
   io=84.8GiB (91.1GB), run=120001-120001msec

With this patch:
Run status group 0 (all jobs):
   READ: bw=761MiB/s (798MB/s), 761MiB/s-761MiB/s (798MB/s-798MB/s),
   io=89.2GiB (95.8GB), run=120001-120001msec

About 5% improvement.
Signed-off-by: NXiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

io_uring is the only user of io-wq, and now it uses only io-wq callback
for all its requests, namely io_wq_submit_work(). Instead of storing
work->runner callback in each instance of io_wq_work, keep it in io-wq
itself.

pros:
- reduces io_wq_work size
- more robust -- ->func won't be invalidated with mem{cpy,set}(req)
- helps other work
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

If the original task is (or has) exited, then the task work will not get
queued properly. Allow for using the io-wq manager task to queue this
work for execution, and ensure that the io-wq manager notices and runs
this work if woken up (or exiting).
Reported-by: NDan Melnic <dmm@fb.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We always punt async buffered writes to an io-wq helper, as the core
kernel does not have IOCB_NOWAIT support for that. Most buffered async
writes complete very quickly, as it's just a copy operation. This means
that doing multiple locking roundtrips on the shared wqe lock for each
buffered write is wasteful. Additionally, buffered writes are hashed
work items, which means that any buffered write to a given file is
serialized.

Keep identicaly hashed work items contiguously in @wqe->work_list, and
track a tail for each hash bucket. On dequeue of a hashed item, splice
all of the same hash in one go using the tracked tail. Until the batch
is done, the caller doesn't have to synchronize with the wqe or worker
locks again.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

work->data and work->list are shared in union. io_wq_assign_next() sets
->data if a req having a linked_timeout, but then io-wq may want to use
work->list, e.g. to do re-enqueue of a request, so corrupting ->data.

->data is not necessary, just remove it and extract linked_timeout
through @Link_list.

Fixes: 60cf46ae ("io-wq: hash dependent work")
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

It's a preparation patch removing io_wq_enqueue_hashed(), which
now should be done by io_wq_hash_work() + io_wq_enqueue().

Also, set hash value for dependant works, and do it as late as possible,
because req->file can be unavailable before. This hash will be ignored
by io-wq.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

First it changes io-wq interfaces. It replaces {get,put}_work() with
free_work(), which guaranteed to be called exactly once. It also enforces
free_work() callback to be non-NULL.

io_uring follows the changes and instead of putting a submission reference
in io_put_req_async_completion(), it will be done in io_free_work(). As
removes io_get_work() with corresponding refcount_inc(), the ref balance
is maintained.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

IO_WQ_WORK_CB is used only for linked timeouts, which will be armed
before the work setup (i.e. mm, override creds, etc). The setup
shouldn't take long, so it's ok to arm it a bit later and get rid
of IO_WQ_WORK_CB.

Make io-wq call work->func() only once, callbacks will handle the rest.
i.e. the linked timeout handler will do the actual issue. And as a
bonus, it removes an extra indirect call.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

IO_WQ_WORK_HAS_MM is set but never used, remove it.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

io_wq_flush() is buggy, during cancelation of a flush, the associated
work may be passed to the caller's (i.e. io_uring) @match callback. That
callback is expecting it to be embedded in struct io_kiocb. Cancelation
of internal work probably doesn't make a lot of sense to begin with.

As the flush helper is no longer used, just delete it and the associated
work flag.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We use ->task_pid for exit cancellation, but we need to ensure it's
cleared to zero for io_req_work_grab_env() to do the right thing. Take
a suggestion from Bart and clear the whole thing, just setting the
function passed in. This makes it more future proof as well.

Fixes: 36282881 ("io-wq: add io_wq_cancel_pid() to cancel based on a specific pid")
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Add a helper that allows the caller to cancel work based on what mm
it belongs to. This allows io_uring to cancel work from a given
task or thread when it exits.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Some work items need this for relative path lookup, make it available
like the other inherited credentials/mm/etc.

Cc: stable@vger.kernel.org # 5.3+
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We're not consistent in how the file table is grabbed and assigned if we
have a command linked that requires the use of it.

Add ->file_table to the io_op_defs[] array, and use that to determine
when to grab the table instead of having the handlers set it if they
need to defer. This also means we can kill the IO_WQ_WORK_NEEDS_FILES
flag. We always initialize work->files, so io-wq can just check for
that.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Export a helper to attach to an existing io-wq, rather than setting up
a new one. This is doable now that we have reference counted io_wq's.
Reported-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

We currently setup the io_wq with a static set of mm and creds. Even for
a single-use io-wq per io_uring, this is suboptimal as we have may have
multiple enters of the ring. For sharing the io-wq backend, it doesn't
work at all.

Switch to passing in the creds and mm when the work item is setup. This
means that async work is no longer deferred to the io_uring mm and creds,
it is done with the current mm and creds.

Flag this behavior with IORING_FEAT_CUR_PERSONALITY, so applications know
they can rely on the current personality (mm and creds) being the same
for direct issue and async issue.
Reviewed-by: NStefan Metzmacher <metze@samba.org>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

io-wq assumes that work will complete fast (and not block), so it
doesn't create a new worker when work is enqueued, if we already have
at least one worker running. This is done on the assumption that if work
is running, then it will complete fast.

Add an option to force io-wq to fork a new worker for work queued. This
is signaled by setting IO_WQ_WORK_CONCURRENT on the work item. For that
case, io-wq will create a new worker, even though workers are already
running.
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 reverts commit 8cdda87a, we now have several use csaes for this
helper. Reinstate it.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

To avoid going to sleep only to get woken shortly thereafter, spin
briefly for new work upon completion of work.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

If someone removes a node from a list, and then later adds it back to
a list, we can have invalid data in ->next. This can cause all sorts
of issues. One such use case is the IORING_OP_POLL_ADD command, which
will do just that if we race and get woken twice without any pending
events. This is a pretty rare case, but can happen under extreme loads.
Dan reports that he saw the following crash:

BUG: kernel NULL pointer dereference, address: 0000000000000000
PGD d283ce067 P4D d283ce067 PUD e5ca04067 PMD 0
Oops: 0002 [#1] SMP
CPU: 17 PID: 10726 Comm: tao:fast-fiber Kdump: loaded Not tainted 5.2.9-02851-gac7bc042d2d1 #116
Hardware name: Quanta Twin Lakes MP/Twin Lakes Passive MP, BIOS F09_3A17 05/03/2019
RIP: 0010:io_wqe_enqueue+0x3e/0xd0
Code: 34 24 74 55 8b 47 58 48 8d 6f 50 85 c0 74 50 48 89 df e8 35 7c 75 00 48 83 7b 08 00 48 8b 14 24 0f 84 84 00 00 00 48 8b 4b 10 <48> 89 11 48 89 53 10 83 63 20 fe 48 89 c6 48 89 df e8 0c 7a 75 00
RSP: 0000:ffffc90006858a08 EFLAGS: 00010082
RAX: 0000000000000002 RBX: ffff889037492fc0 RCX: 0000000000000000
RDX: ffff888e40cc11a8 RSI: ffff888e40cc11a8 RDI: ffff889037492fc0
RBP: ffff889037493010 R08: 00000000000000c3 R09: ffffc90006858ab8
R10: 0000000000000000 R11: 0000000000000000 R12: ffff888e40cc11a8
R13: 0000000000000000 R14: 00000000000000c3 R15: ffff888e40cc1100
FS:  00007fcddc9db700(0000) GS:ffff88903fa40000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000e479f5003 CR4: 00000000007606e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
 <IRQ>
 io_poll_wake+0x12f/0x2a0
 __wake_up_common+0x86/0x120
 __wake_up_common_lock+0x7a/0xc0
 sock_def_readable+0x3c/0x70
 tcp_rcv_established+0x557/0x630
 tcp_v6_do_rcv+0x118/0x3c0
 tcp_v6_rcv+0x97e/0x9d0
 ip6_protocol_deliver_rcu+0xe3/0x440
 ip6_input+0x3d/0xc0
 ? ip6_protocol_deliver_rcu+0x440/0x440
 ipv6_rcv+0x56/0xd0
 ? ip6_rcv_finish_core.isra.18+0x80/0x80
 __netif_receive_skb_one_core+0x50/0x70
 netif_receive_skb_internal+0x2f/0xa0
 napi_gro_receive+0x125/0x150
 mlx5e_handle_rx_cqe+0x1d9/0x5a0
 ? mlx5e_poll_tx_cq+0x305/0x560
 mlx5e_poll_rx_cq+0x49f/0x9c5
 mlx5e_napi_poll+0xee/0x640
 ? smp_reschedule_interrupt+0x16/0xd0
 ? reschedule_interrupt+0xf/0x20
 net_rx_action+0x286/0x3d0
 __do_softirq+0xca/0x297
 irq_exit+0x96/0xa0
 do_IRQ+0x54/0xe0
 common_interrupt+0xf/0xf
 </IRQ>
RIP: 0033:0x7fdc627a2e3a
Code: 31 c0 85 d2 0f 88 f6 00 00 00 55 48 89 e5 41 57 41 56 4c 63 f2 41 55 41 54 53 48 83 ec 18 48 85 ff 0f 84 c7 00 00 00 48 8b 07 <41> 89 d4 49 89 f5 48 89 fb 48 85 c0 0f 84 64 01 00 00 48 83 78 10

when running a networked workload with about 5000 sockets being polled
for. Fix this by clearing node->next when the node is being removed from
the list.

Fixes: 6206f0e1 ("io-wq: shrink io_wq_work a bit")
Reported-by: NDan Melnic <dmm@fb.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Since commit b18fdf71 ("io_uring: simplify io_req_link_next()"),
the io_wq_current_is_worker function is no longer needed, clean it
up.
Signed-off-by: NJackie Liu <liuyun01@kylinos.cn>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

syzbot reports:

kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 9217 Comm: io_uring-sq Not tainted 5.4.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:creds_are_invalid kernel/cred.c:792 [inline]
RIP: 0010:__validate_creds include/linux/cred.h:187 [inline]
RIP: 0010:override_creds+0x9f/0x170 kernel/cred.c:550
Code: ac 25 00 81 fb 64 65 73 43 0f 85 a3 37 00 00 e8 17 ab 25 00 49 8d 7c
24 10 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84
c0 74 08 3c 03 0f 8e 96 00 00 00 41 8b 5c 24 10 bf
RSP: 0018:ffff88809c45fda0 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 0000000043736564 RCX: ffffffff814f3318
RDX: 0000000000000002 RSI: ffffffff814f3329 RDI: 0000000000000010
RBP: ffff88809c45fdb8 R08: ffff8880a3aac240 R09: ffffed1014755849
R10: ffffed1014755848 R11: ffff8880a3aac247 R12: 0000000000000000
R13: ffff888098ab1600 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffd51c40664 CR3: 0000000092641000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
  io_sq_thread+0x1c7/0xa20 fs/io_uring.c:3274
  kthread+0x361/0x430 kernel/kthread.c:255
  ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
Modules linked in:
---[ end trace f2e1a4307fbe2245 ]---
RIP: 0010:creds_are_invalid kernel/cred.c:792 [inline]
RIP: 0010:__validate_creds include/linux/cred.h:187 [inline]
RIP: 0010:override_creds+0x9f/0x170 kernel/cred.c:550
Code: ac 25 00 81 fb 64 65 73 43 0f 85 a3 37 00 00 e8 17 ab 25 00 49 8d 7c
24 10 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84
c0 74 08 3c 03 0f 8e 96 00 00 00 41 8b 5c 24 10 bf
RSP: 0018:ffff88809c45fda0 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 0000000043736564 RCX: ffffffff814f3318
RDX: 0000000000000002 RSI: ffffffff814f3329 RDI: 0000000000000010
RBP: ffff88809c45fdb8 R08: ffff8880a3aac240 R09: ffffed1014755849
R10: ffffed1014755848 R11: ffff8880a3aac247 R12: 0000000000000000
R13: ffff888098ab1600 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffd51c40664 CR3: 0000000092641000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

which is caused by slab fault injection triggering a failure in
prepare_creds(). We don't actually need to create a copy of the creds
as we're not modifying it, we just need a reference on the current task
creds. This avoids the failure case as well, and propagates the const
throughout the stack.

Fixes: 181e448d ("io_uring: async workers should inherit the user creds")
Reported-by: syzbot+5320383e16029ba057ff@syzkaller.appspotmail.com
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Currently we're using 40 bytes for the io_wq_work structure, and 16 of
those is the doubly link list node. We don't need doubly linked lists,
we always add to tail to keep things ordered, and any other use case
is list traversal with deletion. For the deletion case, we can easily
support any node deletion by keeping track of the previous entry.

This shrinks io_wq_work to 32 bytes, and subsequently io_kiock from
io_uring to 216 to 208 bytes.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

If we don't inherit the original task creds, then we can confuse users
like fuse that pass creds in the request header. See link below on
identical aio issue.

Link: https://lore.kernel.org/linux-fsdevel/26f0d78e-99ca-2f1b-78b9-433088053a61@scylladb.com/T/#uSigned-off-by: NJens Axboe <axboe@kernel.dk>

We currently pass in 4 arguments outside of the bounded size. In
preparation for adding one more argument, let's bundle them up in
a struct to make it more readable.

No functional changes in this patch.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

When we find new work to process within the work handler, we queue the
linked timeout before we have issued the new work. This can be
problematic for very short timeouts, as we have a window where the new
work isn't visible.

Allow the work handler to store a callback function for this in the work
item, and flag it with IO_WQ_WORK_CB if the caller has done so. If that
is set, then io-wq will call the callback when it has setup the new work
item.
Reported-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

For cancellation, we need to ensure that the work item stays valid for
as long as ->cur_work is valid. Right now we can't safely dereference
the work item even under the wqe->lock, because while the ->cur_work
pointer will remain valid, the work could be completing and be freed
in parallel.

Only invoke ->get/put_work() on items we know that the caller queued
themselves. Add IO_WQ_WORK_INTERNAL for io-wq to use, which is needed
when we're queueing a flush item, for instance.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Since we switched to io-wq, the dependent link optimization for when to
pass back work inline has been broken. Fix this by providing a suitable
io-wq helper for io_uring to use to detect when to do this.

Fixes: 561fb04a ("io_uring: replace workqueue usage with io-wq")
Signed-off-by: NJens Axboe <axboe@kernel.dk>

io_uring supports request types that basically have two different
lifetimes:

1) Bounded completion time. These are requests like disk reads or writes,
   which we know will finish in a finite amount of time.
2) Unbounded completion time. These are generally networked IO, where we
   have no idea how long they will take to complete. Another example is
   POLL commands.

This patch provides support for io-wq to handle these differently, so we
don't starve bounded requests by tying up workers for too long. By default
all work is bounded, unless otherwise specified in the work item.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This adds support for IORING_OP_ASYNC_CANCEL, which will attempt to
cancel requests that have been punted to async context and are now
in-flight. This works for regular read/write requests to files, as
long as they haven't been started yet. For socket based IO (or things
like accept4(2)), we can cancel work that is already running as well.

To cancel a request, the sqe must have ->addr set to the user_data of
the request it wishes to cancel. If the request is cancelled
successfully, the original request is completed with -ECANCELED
and the cancel request is completed with a result of 0. If the
request was already running, the original may or may not complete
in error. The cancel request will complete with -EALREADY for that
case. And finally, if the request to cancel wasn't found, the cancel
request is completed with -ENOENT.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This is in preparation for adding opcodes that need to add new files
in a process file table, system calls like open(2) or accept4(2).

If an opcode needs this, it must set IO_WQ_WORK_NEEDS_FILES in the work
item. If work that needs to get punted to async context have this
set, the async worker will assume the original task file table before
executing the work.

Note that opcodes that need access to the current files of an
application cannot be done through IORING_SETUP_SQPOLL.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

This adds support for io-wq, a smaller and specialized thread pool
implementation. This is meant to replace workqueues for io_uring. Among
the reasons for this addition are:

- We can assign memory context smarter and more persistently if we
  manage the life time of threads.

- We can drop various work-arounds we have in io_uring, like the
  async_list.

- We can implement hashed work insertion, to manage concurrency of
  buffered writes without needing a) an extra workqueue, or b)
  needlessly making the concurrency of said workqueue very low
  which hurts performance of multiple buffered file writers.

- We can implement cancel through signals, for cancelling
  interruptible work like read/write (or send/recv) to/from sockets.

- We need the above cancel for being able to assign and use file tables
  from a process.

- We can implement a more thorough cancel operation in general.

- We need it to move towards a syslet/threadlet model for even faster
  async execution. For that we need to take ownership of the used
  threads.

This list is just off the top of my head. Performance should be the
same, or better, at least that's what I've seen in my testing. io-wq
supports basic NUMA functionality, setting up a pool per node.

io-wq hooks up to the scheduler schedule in/out just like workqueue
and uses that to drive the need for more/less workers.
Acked-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NJens Axboe <axboe@kernel.dk>