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io_get_cqe() is expensive because of a bunch of loads, masking, etc.
However, most of the time we should have enough of entries in the CQ,
so we can cache two pointers representing a range of contiguous CQE
memory we can use. When the range is exhausted we'll go through a slower
path to set up a new range. When there are no CQEs avaliable, pointers
will naturally point to the same address.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/487eeef00f3146537b3d9c1a9cef2fc0b9a86f81.1649771823.git.asml.silence@gmail.com
[axboe: santinel -> sentinel]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Considering all inlining io_submit_sqe() is huge and usually ends up
calling some other functions.
We decrement @left in io_submit_sqes() just before calling
io_submit_sqe() and use it later after the call. Considering how huge
io_submit_sqe() is, there is not much hope @left will be treated
gracefully by compilers.
Decrement it after the call, not only it's easier on register spilling
and probably saves stack write/read, but also at least for x64 uses
CPU flags set by the dec instead of doing (read/write and tests).
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/807f9a276b54ee8ff4e42e2b78721484f1c71743.1649771823.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Instead of keeping @submitted in io_submit_sqes(), which for each
iteration requires comparison with the initial number of SQEs, store the
number of SQEs left to submit. We'll need nr only for when we're done
with SQE handling.
note: if we can't allocate a req for the first SQE we always has been
returning -EAGAIN to the userspace, save this behaviour by looking into
the cache in a slow path.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/c3b3df9aeae4c2f7a53fd8386385742e4e261e77.1649771823.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
All good users should not set IOSQE_IO_*LINK flags for the last request
of a link. io_uring flushes collected links at the end of submission,
but it's not the optimal way and so we don't care too much about it.
Replace io_queue_sqe() call with io_queue_sqe_fallback() as the former
one is inlined and will generate a bunch of extra code. This will also
help compilers with the submission path inlining.
> size ./fs/io_uring.o
text data bss dec hex filename
87265 13734 8 101007 18a8f ./fs/io_uring.o
> size ./fs/io_uring.o
text data bss dec hex filename
87073 13734 8 100815 189cf ./fs/io_uring.o
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/01fb5e417ef49925d544a0b0bae30409845ed2b4.1649771823.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We can do CQE filling a bit more efficiently when req->cqe is fully
filled by memcpy()'ing it to the userspace instead of doing it field by
field. It's easier on register spilling, removes a couple of extra
loads/stores and write combines two u32 memory writes.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/ee3f514ff28b1fe3347a8eca93a9d91647f2eaad.1649771823.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We already have req->{result,user_data,cflags}, which mimic struct
io_uring_cqe and are intended to store CQE data. Combine them into a
struct io_uring_cqe field.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/e1efe65d5005cd6a9ec3440767eb15a9fa9351cf.1649771823.git.asml.silence@gmail.com
[axboe: add mirror cqe to cater to fd union]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
There is an old API nuisance where io_uring's SCM accounting functions
traverse fixed file tables and so requires them to be set in advance,
which leads to some implicit rules of how io_sqe_file_register() should
be used.
__io_sqe_files_scm() now works with only one file at a time, pass a file
directly and get rid of all fixed table dereferencing inside. Clean
io_sqe_file_register() callers.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/fb32031d892e61a7748c70da7999725d5e798671.1649334991.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Channel all SCM accounting through io_sqe_file_register(), so we do it
uniformely for updates and initial registration and can kill duplicated
code. Registration might be slightly slower in some case, but first we
skip most of SCM accounting now so it's not a problem. Moreover, it's
nicer for an empty set registration as we don't even try to allocate
skb for them anymore.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/6c9afbeb22812777d0c43e52353b63db5b87ed1e.1649334991.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
io_uring deals with file reference loops by registering all fixed files
in the SCM/GC infrastrucure. However, only a small subset of all file
types can keep long-term references to other files and those that don't
are not interesting for the garbage collector as they can't be in a
reference loop. They neither can be directly recycled by GC nor affect
loop searching.
Let's skip io_uring SCM accounting for loop-less files, i.e. all but
af_unix sockets, quite imroving fixed file updates performance and
greatly helpnig with memory footprint.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/9c44ecf6e89d69130a8c4360cce2183ffc5ddd6f.1649277098.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We don't need to call this for every loop. This is particularly
troublesome if we are task_work intensive, and get woken more often than
we desire due to that.
Just do it at the end, that's always safe as we initialize the waitqueue
list head anyway. This can save a considerable amount of hammering on
the waitqueue lock, which is also hot from the request completion side.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
In most cases io_put_task() is called from the submitter task and go
through a higly optimised fast path, which has to be inlined. The other
branch though is bulkier and we don't care about it as much because it
implies atomics and other heavy calls. Extract it into a helper, which
is expected not to be inlined.
[before] size ./fs/io_uring.o
text data bss dec hex filename
89328 13646 8 102982 19246 ./fs/io_uring.o
[after] size ./fs/io_uring.o
text data bss dec hex filename
89096 13646 8 102750 1915e ./fs/io_uring.o
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/dec213db0e0b8605132da81e0a0be687a4d140cb.1648209006.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Refactor io_ring_submit_[un]lock(), make it accept issue_flags and
remove manual IO_URING_F_UNLOCKED checks. It also allows us to place
lockdep annotations inside instead of sprinkling them in a bunch of
places. There is only one user that doesn't fit now, so hand code
locking in __io_rsrc_put_work().
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/e55c2c06767676a801252e8094c9ab09912487a4.1648209006.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Both submittion and iopolling requires holding uring_lock. IOPOLL can
users do them together in a single syscall, however it would still do 2
pairs of lock/unlock. Optimise this case combining locking into one
lock/unlock pair, which especially nice for low QD.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/034b6c41658648ad3ad3c9485ac8eb546f010bc4.1647957378.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Syscall should only iopoll for events when it's a IOPOLL ring and is not
SQPOLL. Instead of check both flags every time we can save it in ring
flags so it's easier to use. We don't care much about an extra if there,
however it will be inconvenient to copy-paste this chunk with checks in
future patches.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/7fd2f8fc2606305aa06dd8c0ff8f76a66b39c383.1647957378.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
IOPOLL doesn't use additional arguments like sigsets, but it still
needs some basic verification, which is currently done by
io_get_ext_arg(). This patch adds a separate function for the IOPOLL
path, which is a bit simpler and doesn't do extra. This prepares us for
further patches, which would have hurt inlining in the hot path otherwise.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/71b23fca412e3374b74be7711cfd42a3d9d5dfe0.1647957378.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Move fast check out of io_queue_next(), it makes req->flags checks in
__io_submit_flush_completions() a bit clearer and grants us better
comtrol, e.g. can remove now not justified unlikely() in
__io_submit_flush_completions(). Also, we don't care about having this
check in io_free_req() as the function is a slow path and
io_req_find_next() handles it correctly.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/1f9e1cc80adbb11b37017d511df4a2c6141a3f08.1647897811.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
There is a new (req->flags & REQ_F_POLLED) check in
__io_submit_flush_completions() for poll recycling, however
io_free_batch_list() is a much better place for it. First, we prefer it
after putting the last req ref just to avoid potential problems in the
future. Also, it'll enable the recycling for IOPOLL and also will place
it closer to all other req->flags bits clean up requests.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/31dfe1dafda66ba3ce36b301884ec7e162c777d1.1647897811.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We do several req->flags checks in the fast path of
io_free_batch_list(). One explicit check of REQ_F_REFCOUNT, and two
other hidden in io_queue_next() and io_dismantle_req(). Moreover, there
is a io_req_put_rsrc_locked() call in between, so there is no hope
req->flags will be preserved in registers.
All those flags if not a slow path than definitely a slower path, so
put them all under a single flags mask check and save several mem
reloads and ifs.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/0fb493f73f2009aea395c570c2932fecaa4e1244.1647897811.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
If all completed requests in io_do_iopoll() were marked with
REQ_F_CQE_SKIP, we'll not only skip CQE posting but also
io_free_batch_list() leaking memory and resources.
Move @nr_events increment before REQ_F_CQE_SKIP check. We'll potentially
return the value greater than the real one, but iopolling will deal with
it and the userspace will re-iopoll if needed. In anyway, I don't think
there are many use cases for REQ_F_CQE_SKIP + IOPOLL.
Fixes: 83a13a4181b0e ("io_uring: tweak iopoll CQE_SKIP event counting")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/5072fc8693fbfd595f89e5d4305bfcfd5d2f0a64.1650186611.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We just return failure in this case, but we need to release the iovec
first. If we're doing IO with more than FAST_IOV segments, then the
iovec is allocated and must be freed.
Reported-by: syzbot+96b43810dfe9c3bb95ed@syzkaller.appspotmail.com
Fixes: 584b0180f0f4 ("io_uring: move read/write file prep state into actual opcode handler")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We should not return an error code in req->result in
io_poll_check_events(), because it may get mangled and returned as
success. Just return the error code directly, the callers will fail the
request or proceed accordingly.
Fixes: 6bf9c47a3989 ("io_uring: defer file assignment")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/5f03514ee33324dc811fb93df84aee0f695fb044.1649862516.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Ensure that only 0 is passed for pad here.
Fixes: c73ebb685fb6 ("io_uring: add timeout support for io_uring_enter()")
Signed-off-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220412163042.2788062-5-dylany@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Only allow resv field to be 0 in struct io_uring_rsrc_update user
arguments.
Fixes: e7a6c00dc77a ("io_uring: add support for registering ring file descriptors")
Signed-off-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220412163042.2788062-4-dylany@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Verify that the user does not pass in anything but 0 for this field.
Fixes: 992da01aa932 ("io_uring: change registration/upd/rsrc tagging ABI")
Signed-off-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220412163042.2788062-3-dylany@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Move validation to be more consistently straight after
copy_from_user. This is already done in io_register_rsrc_update and so
this removes that redundant check.
Signed-off-by: Dylan Yudaken <dylany@fb.com>
Link: https://lore.kernel.org/r/20220412163042.2788062-2-dylany@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
io-wq work cancellation path can't take uring_lock as how it's done on
file assignment, we have to handle IO_WQ_WORK_CANCEL first, this fixes
encountered hangs.
Fixes: 6bf9c47a3989 ("io_uring: defer file assignment")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/0d9b9f37841645518503f6a207e509d14a286aba.1649773463.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
There are two reasons why this isn't the best idea:
- It's an odd area to grab a bit of storage space, hence it's an odd area
to grab storage from.
- It puts the 3rd io_kiocb cacheline into the hot path, where normal hot
path just needs the first two.
Use 'cflags' for joint fd/cflags storage. We only need fd until we
successfully issue, and we only need cflags once a request is done and is
completed.
Fixes: 6bf9c47a3989 ("io_uring: defer file assignment")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
In preparation for fixing a regression with pulling in an extra cacheline
for IO that doesn't usually touch the last cacheline of the io_kiocb,
move the cached location of apoll->events to space shared with some other
completion data. Like cflags, this isn't used until after the request
has been completed, so we can piggy back on top of comp_list.
Fixes: 81459350d581 ("io_uring: cache req->apoll->events in req->cflags")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
-1 tells use to use the current position, but we check if the file is
a stream regardless of that. Fix up io_kiocb_update_pos() to only
dip into file if we need to. This is both more efficient and also drops
12 bytes of text on aarch64 and 64 bytes on x86-64.
Fixes: b4aec4001595 ("io_uring: do not recalculate ppos unnecessarily")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Give applications a way to tell if the kernel supports sane linked files,
as in files being assigned at the right time to be able to reliably
do <open file direct into slot X><read file from slot X> while using
IOSQE_IO_LINK to order them.
Not really a bug fix, but flag it as such so that it gets pulled in with
backports of the deferred file assignment.
Fixes: 6bf9c47a3989 ("io_uring: defer file assignment")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
io_flush_timeouts() assumes the timeout isn't in progress of triggering
or being removed/canceled, so it unconditionally removes it from the
timeout list and attempts to cancel it.
Leave it on the list and let the normal timeout cancelation take care
of it.
Cc: stable@vger.kernel.org # 5.5+
Signed-off-by: Jens Axboe <axboe@kernel.dk>
It's safer to not touch scm_fp_list after we queued an skb to which it
was assigned, there might be races lurking if we screw subtle sync
guarantees on the io_uring side.
Fixes: 6b06314c47e14 ("io_uring: add file set registration")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Don't forget to array_index_nospec() for indexes before updating rsrc
tags in __io_sqe_files_update(), just use already safe and precalculated
index @i.
Fixes: c3bdad0271834 ("io_uring: add generic rsrc update with tags")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Similarly to the way it is done im mbind syscall.
Cc: stable@vger.kernel.org # 5.14
Fixes: fe76421d1da1dcdb ("io_uring: allow user configurable IO thread CPU affinity")
Signed-off-by: Eugene Syromiatnikov <esyr@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
