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kmalloc'ing struct io_notif is too expensive when done frequently, cache
them as many other resources in io_uring. Keep two list, the first one
is from where we're getting notifiers, it's protected by ->uring_lock.
The second is protected by ->completion_lock, to which we queue released
notifiers. Then we splice one list into another when needed.
Signed-off-by: Pavel Begunkov <[email protected]>
Link: https://lore.kernel.org/r/9dec18f7fcbab9f4bd40b96e5ae158b119945230.1657643355.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <[email protected]>
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Add internal part of send zerocopy notifications. There are two main
structures, the first one is struct io_notif, which carries inside
struct ubuf_info and maps 1:1 to it. io_uring will be binding a number
of zerocopy send requests to it and ask to complete (aka flush) it. When
flushed and all attached requests and skbs complete, it'll generate one
and only one CQE. There are intended to be passed into the network layer
as struct msghdr::msg_ubuf.
The second concept is notification slots. The userspace will be able to
register an array of slots and subsequently addressing them by the index
in the array. Slots are independent of each other. Each slot can have
only one notifier at a time (called active notifier) but many notifiers
during the lifetime. When active, a notifier not going to post any
completion but the userspace can attach requests to it by specifying
the corresponding slot while issueing send zc requests. Eventually, the
userspace will want to "flush" the notifier losing any way to attach
new requests to it, however it can use the next atomatically added
notifier of this slot or of any other slot.
When the network layer is done with all enqueued skbs attached to a
notifier and doesn't need the specified in them user data, the flushed
notifier will post a CQE.
Signed-off-by: Pavel Begunkov <[email protected]>
Link: https://lore.kernel.org/r/3ecf54c31a85762bf679b0a432c9f43ecf7e61cc.1657643355.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <[email protected]>
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Make io_put_task() available to non-core parts of io_uring, we'll need
it for notification infrastructure.
Signed-off-by: Pavel Begunkov <[email protected]>
Link: https://lore.kernel.org/r/3686807d4c03b72e389947b0e8692d4d44334ef0.1657643355.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <[email protected]>
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Initialise newly added ->msg_ubuf in io_recv() and io_send().
Signed-off-by: Pavel Begunkov <[email protected]>
Link: https://lore.kernel.org/r/b8f9f263875a4a36e7f26cc5d55ebe315308f57d.1657643355.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <[email protected]>
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* for-5.20/io_uring: (716 commits)
io_uring: ensure REQ_F_ISREG is set async offload
net: fix compat pointer in get_compat_msghdr()
io_uring: Don't require reinitable percpu_ref
io_uring: fix types in io_recvmsg_multishot_overflow
io_uring: Use atomic_long_try_cmpxchg in __io_account_mem
io_uring: support multishot in recvmsg
net: copy from user before calling __get_compat_msghdr
net: copy from user before calling __copy_msghdr
io_uring: support 0 length iov in buffer select in compat
io_uring: fix multishot ending when not polled
io_uring: add netmsg cache
io_uring: impose max limit on apoll cache
io_uring: add abstraction around apoll cache
io_uring: move apoll cache to poll.c
io_uring: consolidate hash_locked io-wq handling
io_uring: clear REQ_F_HASH_LOCKED on hash removal
io_uring: don't race double poll setting REQ_F_ASYNC_DATA
io_uring: don't miss setting REQ_F_DOUBLE_POLL
io_uring: disable multishot recvmsg
io_uring: only trace one of complete or overflow
...
Signed-off-by: Jens Axboe <[email protected]>
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git://git.kernel.org/pub/scm/linux/kernel/git/kuba/linux into for-5.20/io_uring-zerocopy-send
Merge prep net series for io_uring tx zc from the Jakub's tree.
* 'io_uring-zerocopy-send' of git://git.kernel.org/pub/scm/linux/kernel/git/kuba/linux:
net: fix uninitialised msghdr->sg_from_iter
tcp: support externally provided ubufs
ipv6/udp: support externally provided ubufs
ipv4/udp: support externally provided ubufs
net: introduce __skb_fill_page_desc_noacc
net: introduce managed frags infrastructure
net: Allow custom iter handler in msghdr
skbuff: carry external ubuf_info in msghdr
skbuff: add SKBFL_DONT_ORPHAN flag
skbuff: don't mix ubuf_info from different sources
ipv6: avoid partial copy for zc
ipv4: avoid partial copy for zc
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If we're creating a page cache page with FGP_CREAT but FGP_NOWAIT is
set, we should dial back the gfp flags to avoid frivolous blocking
which is trivial to hit in low memory conditions:
[ 10.117661] __schedule+0x8c/0x550
[ 10.118305] schedule+0x58/0xa0
[ 10.118897] schedule_timeout+0x30/0xdc
[ 10.119610] __wait_for_common+0x88/0x114
[ 10.120348] wait_for_completion+0x1c/0x24
[ 10.121103] __flush_work.isra.0+0x16c/0x19c
[ 10.121896] flush_work+0xc/0x14
[ 10.122496] __drain_all_pages+0x144/0x218
[ 10.123267] drain_all_pages+0x10/0x18
[ 10.123941] __alloc_pages+0x464/0x9e4
[ 10.124633] __folio_alloc+0x18/0x3c
[ 10.125294] __filemap_get_folio+0x17c/0x204
[ 10.126084] iomap_write_begin+0xf8/0x428
[ 10.126829] iomap_file_buffered_write+0x144/0x24c
[ 10.127710] xfs_file_buffered_write+0xe8/0x248
[ 10.128553] xfs_file_write_iter+0xa8/0x120
[ 10.129324] io_write+0x16c/0x38c
[ 10.129940] io_issue_sqe+0x70/0x1cc
[ 10.130617] io_queue_sqe+0x18/0xfc
[ 10.131277] io_submit_sqes+0x5d4/0x600
[ 10.131946] __arm64_sys_io_uring_enter+0x224/0x600
[ 10.132752] invoke_syscall.constprop.0+0x70/0xc0
[ 10.133616] do_el0_svc+0xd0/0x118
[ 10.134238] el0_svc+0x78/0xa0
Clear IO, FS, and reclaim flags and mark the allocation as GFP_NOWAIT and
add __GFP_NOWARN to avoid polluting dmesg with pointless allocations
failures. A caller with FGP_NOWAIT must be expected to handle the
resulting -EAGAIN return and retry from a suitable context without NOWAIT
set.
Reviewed-by: Shakeel Butt <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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This adds the async buffered write support to XFS. For async buffered
write requests, the request will return -EAGAIN if the ilock cannot be
obtained immediately.
Signed-off-by: Stefan Roesch <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Reviewed-by: Darrick J. Wong <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>
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This patch changes the helper function xfs_ilock_for_iomap such that the
lock mode must be passed in.
Signed-off-by: Stefan Roesch <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Reviewed-by: Darrick J. Wong <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>
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This adds the io_uring_short_write tracepoint to io_uring. A short write
is issued if not all pages that are required for a write are in the page
cache and the async buffered writes have to return EAGAIN.
Signed-off-by: Stefan Roesch <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>
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This is actually an older issue, but we never used to hit the -EAGAIN
path before having done sb_start_write(). Make sure that we always call
kiocb_end_write() if we need to retry the write, so that we keep the
calls to sb_start_write() etc balanced.
Signed-off-by: Jens Axboe <[email protected]>
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This enables the async buffered writes for the filesystems that support
async buffered writes in io-uring. Buffered writes are enabled for
blocks that are already in the page cache or can be acquired with noio.
Signed-off-by: Stefan Roesch <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
[axboe: adapt to 5.20 branch]
Signed-off-by: Jens Axboe <[email protected]>
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This adds a file_modified_async() function to return -EAGAIN if the
request either requires to remove privileges or needs to update the file
modification time. This is required for async buffered writes, so the
request gets handled in the io worker of io-uring.
Signed-off-by: Stefan Roesch <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Reviewed-by: Christian Brauner (Microsoft) <[email protected]>
Reviewed-by: Darrick J. Wong <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>
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This splits off the functions inode_needs_update_time() and
__file_update_time() from the function file_update_time().
This is required to support async buffered writes.
No intended functional changes in this patch.
Signed-off-by: Stefan Roesch <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Reviewed-by: Christian Brauner (Microsoft) <[email protected]>
Reviewed-by: Darrick J. Wong <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>
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This adds the function __remove_file_privs, which allows the caller to
pass the kiocb flags parameter.
No intended functional changes in this patch.
Signed-off-by: Stefan Roesch <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Reviewed-by: Christian Brauner (Microsoft) <[email protected]>
Reviewed-by: Darrick J. Wong <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>
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This introduces the flag FMODE_BUF_WASYNC. If devices support async
buffered writes, this flag can be set. It also modifies the check in
generic_write_checks to take async buffered writes into consideration.
Signed-off-by: Stefan Roesch <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Reviewed-by: Christian Brauner (Microsoft) <[email protected]>
Reviewed-by: Darrick J. Wong <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>
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If iomap_write_iter() encounters -EAGAIN, return -EAGAIN to the caller.
Signed-off-by: Stefan Roesch <[email protected]>
Reviewed-by: Darrick J. Wong <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Christoph Hellwig <[email protected]>
[axboe: make the suggested ternary edit]
Signed-off-by: Jens Axboe <[email protected]>
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This adds async buffered write support to iomap.
This replaces the call to balance_dirty_pages_ratelimited() with the
call to balance_dirty_pages_ratelimited_flags. This allows to specify if
the write request is async or not.
In addition this also moves the above function call to the beginning of
the function. If the function call is at the end of the function and the
decision is made to throttle writes, then there is no request that
io-uring can wait on. By moving it to the beginning of the function, the
write request is not issued, but returns -EAGAIN instead. io-uring will
punt the request and process it in the io-worker.
By moving the function call to the beginning of the function, the write
throttling will happen one page later.
Signed-off-by: Stefan Roesch <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Reviewed-by: Darrick J. Wong <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>
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Add the kiocb flags parameter to the function iomap_page_create().
Depending on the value of the flags parameter it enables different gfp
flags.
No intended functional changes in this patch.
Signed-off-by: Stefan Roesch <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Reviewed-by: Darrick J. Wong <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>
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This adds the helper function balance_dirty_pages_ratelimited_flags().
It adds the parameter flags to balance_dirty_pages_ratelimited().
The flags parameter is passed to balance_dirty_pages(). For async
buffered writes the flag value will be BDP_ASYNC.
If balance_dirty_pages() gets called for async buffered write, we don't
want to wait. Instead we need to indicate to the caller that throttling
is needed so that it can stop writing and offload the rest of the write
to a context that can block.
The new helper function is also used by balance_dirty_pages_ratelimited().
Signed-off-by: Jan Kara <[email protected]>
Signed-off-by: Stefan Roesch <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
[axboe: fix kerneltest bot 'ret' issue]
Signed-off-by: Jens Axboe <[email protected]>
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Transition of wb->dirty_exceeded from 0 to 1 happens before we go to
sleep in balance_dirty_pages() while transition from 1 to 0 happens when
exiting from balance_dirty_pages(), possibly based on old values. This
does not make a lot of sense since wb->dirty_exceeded should simply
reflect whether wb is over dirty limit and so we should ratelimit
entering to balance_dirty_pages() less. Move the two updates together.
Signed-off-by: Jan Kara <[email protected]>
Signed-off-by: Stefan Roesch <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>
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We start background writeback if we are over background threshold after
exiting the main loop in balance_dirty_pages(). This may result in
basing the decision on already stale values (we may have slept for
significant amount of time) and it is also inconvenient for refactoring
needed for async dirty throttling. Move the check into the main waiting
loop.
Signed-off-by: Jan Kara <[email protected]>
Signed-off-by: Stefan Roesch <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>
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If we're offloading requests directly to io-wq because IOSQE_ASYNC was
set in the sqe, we can miss hashing writes appropriately because we
haven't set REQ_F_ISREG yet. This can cause a performance regression
with buffered writes, as io-wq then no longer correctly serializes writes
to that file.
Ensure that we set the flags in io_prep_async_work(), which will cause
the io-wq work item to be hashed appropriately.
Fixes: 584b0180f0f4 ("io_uring: move read/write file prep state into actual opcode handler")
Link: https://lore.kernel.org/io-uring/20220608080054.GB22428@xsang-OptiPlex-9020/
Reported-by: kernel test robot <[email protected]>
Tested-by: Yin Fengwei <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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A previous change enabled external users to copy the data before
calling __get_compat_msghdr(), but didn't modify get_compat_msghdr() or
__io_compat_recvmsg_copy_hdr() to take that into account. They are both
stil passing in the __user pointer rather than the copied version.
Ensure we pass in the kernel struct, not the pointer to the user data.
Link: https://lore.kernel.org/all/[email protected]/
Fixes: 1a3e4e94a1b9 ("net: copy from user before calling __get_compat_msghdr")
Reported-by: Marek Szyprowski <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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The commit 8bb649ee1da3 ("io_uring: remove ring quiesce for
io_uring_register") removed the worklow relying on reinit/resurrection
of the percpu_ref, hence, initialization with that requested is a relic.
This is based on code review, this causes no real bug (and theoretically
can't). Technically it's a revert of commit 214828962dea ("io_uring:
initialize percpu refcounters using PERCU_REF_ALLOW_REINIT") but since
the flag omission is now justified, I'm not making this a revert.
Fixes: 8bb649ee1da3 ("io_uring: remove ring quiesce for io_uring_register")
Signed-off-by: Michal Koutný <[email protected]>
Acked-by: Roman Gushchin <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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io_recvmsg_multishot_overflow had incorrect types on non x64 system.
But also it had an unnecessary INT_MAX check, which could just be done
by changing the type of the accumulator to int (also simplifying the
casts).
Reported-by: Stephen Rothwell <[email protected]>
Fixes: a8b38c4ce724 ("io_uring: support multishot in recvmsg")
Signed-off-by: Dylan Yudaken <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>
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Use atomic_long_try_cmpxchg instead of
atomic_long_cmpxchg (*ptr, old, new) == old in __io_account_mem.
x86 CMPXCHG instruction returns success in ZF flag, so this
change saves a compare after cmpxchg (and related move
instruction in front of cmpxchg).
Also, atomic_long_try_cmpxchg implicitly assigns old *ptr value
to "old" when cmpxchg fails, enabling further code simplifications.
No functional change intended.
Signed-off-by: Uros Bizjak <[email protected]>
Cc: Jens Axboe <[email protected]>
Cc: Pavel Begunkov <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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Similar to multishot recv, this will require provided buffers to be
used. However recvmsg is much more complex than recv as it has multiple
outputs. Specifically flags, name, and control messages.
Support this by introducing a new struct io_uring_recvmsg_out with 4
fields. namelen, controllen and flags match the similar out fields in
msghdr from standard recvmsg(2), payloadlen is the length of the payload
following the header.
This struct is placed at the start of the returned buffer. Based on what
the user specifies in struct msghdr, the next bytes of the buffer will be
name (the next msg_namelen bytes), and then control (the next
msg_controllen bytes). The payload will come at the end. The return value
in the CQE is the total used size of the provided buffer.
Signed-off-by: Dylan Yudaken <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
[axboe: style fixups, see link]
Signed-off-by: Jens Axboe <[email protected]>
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this is in preparation for multishot receive from io_uring, where it needs
to have access to the original struct user_msghdr.
functionally this should be a no-op.
Acked-by: Paolo Abeni <[email protected]>
Signed-off-by: Dylan Yudaken <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>
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this is in preparation for multishot receive from io_uring, where it needs
to have access to the original struct user_msghdr.
functionally this should be a no-op.
Acked-by: Paolo Abeni <[email protected]>
Signed-off-by: Dylan Yudaken <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>
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Match up work done in "io_uring: allow iov_len = 0 for recvmsg and buffer
select", but for compat code path.
Fixes: a68caad69ce5 ("io_uring: allow iov_len = 0 for recvmsg and buffer select")
Signed-off-by: Dylan Yudaken <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>
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If multishot is not actually polling then return IOU_OK rather than the
result.
If the result was > 0 this will confuse things further up the callstack
which expect a return <= 0.
Fixes: 1300ebb20286 ("io_uring: multishot recv")
Signed-off-by: Dylan Yudaken <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>
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For recvmsg/sendmsg, if they don't complete inline, we currently need
to allocate a struct io_async_msghdr for each request. This is a
somewhat large struct.
Hook up sendmsg/recvmsg to use the io_alloc_cache. This reduces the
alloc + free overhead considerably, yielding 4-5% of extra performance
running netbench.
Signed-off-by: Jens Axboe <[email protected]>
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Caches like this tend to grow to the peak size, and then never get any
smaller. Impose a max limit on the size, to prevent it from growing too
big.
A somewhat randomly chosen 512 is the max size we'll allow the cache
to get. If a batch of frees come in and would bring it over that, we
simply start kfree'ing the surplus.
Signed-off-by: Jens Axboe <[email protected]>
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In preparation for adding limits, and one more user, abstract out the
core bits of the allocation+free cache.
Signed-off-by: Jens Axboe <[email protected]>
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This is where it's used, move the flush handler in there.
Signed-off-by: Jens Axboe <[email protected]>
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Don't duplicate code disabling REQ_F_HASH_LOCKED for IO_URING_F_UNLOCKED
(i.e. io-wq), move the handling into __io_arm_poll_handler().
Signed-off-by: Pavel Begunkov <[email protected]>
Link: https://lore.kernel.org/r/0ff0ffdfaa65b3d536131535c3dad3c63d9b7bb0.1657203020.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <[email protected]>
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Instead of clearing REQ_F_HASH_LOCKED while arming a poll, unset the bit
when we're removing the entry from the table in io_poll_tw_hash_eject().
Signed-off-by: Pavel Begunkov <[email protected]>
Link: https://lore.kernel.org/r/02e48bb88d6f1480c94ac2924c43ad1fbd48e92a.1657203020.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <[email protected]>
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Just as with io_poll_double_prepare() setting REQ_F_DOUBLE_POLL, we can
race with the first poll entry when setting REQ_F_ASYNC_DATA. Move it
under io_poll_double_prepare().
Fixes: a18427bb2d9b ("io_uring: optimise submission side poll_refs")
Signed-off-by: Pavel Begunkov <[email protected]>
Link: https://lore.kernel.org/r/df6920f509c11115aa2bce8b34dc5fdb0eb98920.1657203020.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <[email protected]>
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When adding a second poll entry we should set REQ_F_DOUBLE_POLL
unconditionally. We might race with the first entry removal but that
doesn't change the rule.
Fixes: a18427bb2d9b ("io_uring: optimise submission side poll_refs")
Reported-and-tested-by: [email protected]
Signed-off-by: Pavel Begunkov <[email protected]>
Link: https://lore.kernel.org/r/8b680d83ded07424db83e8745585e7a6d72826ef.1657203020.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <[email protected]>
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recvmsg has semantics that do not make it trivial to extend to
multishot. Specifically it has user pointers and returns data in the
original parameter. In order to make this API useful these will need to be
somehow included with the provided buffers.
For now remove multishot for recvmsg as it is not useful.
Signed-off-by: Dylan Yudaken <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>
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In overflow we see a duplcate line in the trace, and in some cases 3
lines (if initial io_post_aux_cqe fails).
Instead just trace once for each CQE
Signed-off-by: Dylan Yudaken <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>
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Make the trace format consistent with io_uring_complete for cflags
Signed-off-by: Dylan Yudaken <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>
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Support multishot receive for io_uring.
Typical server applications will run a loop where for each recv CQE it
requeues another recv/recvmsg.
This can be simplified by using the existing multishot functionality
combined with io_uring's provided buffers.
The API is to add the IORING_RECV_MULTISHOT flag to the SQE. CQEs will
then be posted (with IORING_CQE_F_MORE flag set) when data is available
and is read. Once an error occurs or the socket ends, the multishot will
be removed and a completion without IORING_CQE_F_MORE will be posted.
The benefit to this is that the recv is much more performant.
* Subsequent receives are queued up straight away without requiring the
application to finish a processing loop.
* If there are more data in the socket (sat the provided buffer size is
smaller than the socket buffer) then the data is immediately
returned, improving batching.
* Poll is only armed once and reused, saving CPU cycles
Signed-off-by: Dylan Yudaken <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>
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Similar to multishot poll, drop multishot accept when CQE overflow occurs.
Signed-off-by: Dylan Yudaken <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>
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On overflow, multishot poll can still complete with the IORING_CQE_F_MORE
flag set.
If in the meantime the user clears a CQE and a the poll was cancelled then
the poll will post a CQE without the IORING_CQE_F_MORE (and likely result
-ECANCELED).
However when processing the application will encounter the non-overflow
CQE which indicates that there will be no more events posted. Typical
userspace applications would free memory associated with the poll in this
case.
It will then subsequently receive the earlier CQE which has overflowed,
which breaks the contract given by the IORING_CQE_F_MORE flag.
Signed-off-by: Dylan Yudaken <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>
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Some use cases of io_post_aux_cqe would not want to overflow as is, but
might want to change the flags/result. For example multishot receive
requires in order CQE, and so if there is an overflow it would need to
stop receiving until the overflow is taken care of.
Signed-off-by: Dylan Yudaken <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>
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For multishot we want a way to signal the caller that multishot has ended
but also this might not be an error return.
For example sockets return 0 when closed, which should end a multishot
recv, but still have a CQE with result 0
Introduce IOU_STOP_MULTISHOT which does this and indicates that the return
code is stored inside req->cqe
Signed-off-by: Dylan Yudaken <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>
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The values returned are a bit confusing, where 0 and 1 have implied
meaning, so add some definitions for them.
Signed-off-by: Dylan Yudaken <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>
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Rather than passing an error back to the user with a buffer attached,
recycle the buffer immediately.
Signed-off-by: Dylan Yudaken <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>
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