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2020-06-30io_uring: factor out grab_env() from defer_prep()Pavel Begunkov
Remove io_req_work_grab_env() call from io_req_defer_prep(), just call it when neccessary. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-30io_uring: do init work in grab_env()Pavel Begunkov
Place io_req_init_async() in io_req_work_grab_env() so it won't be forgotten. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-30io_uring: don't pass def into io_req_work_grab_envPavel Begunkov
Remove struct io_op_def *def parameter from io_req_work_grab_env(), it's trivially deducible from req->opcode and fast. The API is cleaner this way, and also helps the complier to understand that it's a real constant and could be register-cached. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-30io_uring: fix potential use after free on fallback request freePavel Begunkov
After __io_free_req() puts a ctx ref, it should be assumed that the ctx may already be gone. However, it can be accessed when putting the fallback req. Free the req first and then put the ctx. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-30io_uring: kill REQ_F_TIMEOUT_NOSEQPavel Begunkov
There are too many useless flags, kill REQ_F_TIMEOUT_NOSEQ, which can be easily infered from req.timeout itself. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-30io_uring: kill REQ_F_TIMEOUTPavel Begunkov
Now REQ_F_TIMEOUT is set but never used, kill it Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-30io_uring: replace find_next() out param with retPavel Begunkov
Generally, it's better to return a value directly than having out parameter. It's cleaner and saves from some kinds of ugly bugs. May also be faster. Return next request from io_req_find_next() and friends directly instead of passing out parameter. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-30io_uring: deduplicate freeing linked timeoutsPavel Begunkov
Linked timeout cancellation code is repeated in in io_req_link_next() and io_fail_links(), and they differ in details even though shouldn't. Basing on the fact that there is maximum one armed linked timeout in a link, and it immediately follows the head, extract a function that will check for it and defuse. Justification: - DRY and cleaner - better inlining for io_req_link_next() (just 1 call site now) - isolates linked_timeouts from common path - reduces time under spinlock for failed links - actually less code Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> [axboe: fold in locking fix for io_fail_links()] Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-29io_uring: fix missing wake_up io_rw_reissue()Pavel Begunkov
Don't forget to wake up a process to which io_rw_reissue() added task_work. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-28io_uring: fix iopoll -EAGAIN handlingPavel Begunkov
req->iopoll() is not necessarily called by a task that submitted a request. Because of that, it's dangerous to grab_env() and punt async on -EGAIN, potentially grabbing another task's mm and corrupting its memory. Do resubmit from the submitter task context. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-28io_uring: do task_work_run() during iopollPavel Begunkov
There are a lot of new users of task_work, and some of task_work_add() may happen while we do io polling, thus make iopoll from time to time to do task_work_run(), so it doesn't poll for sitting there reqs. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-28io_uring: clean up req->result setting by rwPavel Begunkov
Assign req->result to io_size early in io_{read,write}(), it's enough and makes it more straightforward. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-28io_uring: kill REQ_F_LINK_NEXTPavel Begunkov
After pulling nxt from a request, it's no more a links head, so clear REQ_F_LINK_HEAD. Absence of this flag also indicates that there are no linked requests, so replacing REQ_F_LINK_NEXT, which can be killed. Linked timeouts also behave leaving the flag intact when necessary. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-28io_uring: cosmetic changes for batch freePavel Begunkov
Move all batch free bits close to each other and rename in a consistent way. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-28io_uring: batch-free linked requests as wellPavel Begunkov
There is no reason to not batch deallocation of linked requests. Take away its next req first and handle it as everything else in io_req_multi_free(). Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-28io_uring: dismantle req early and remove need_iterPavel Begunkov
Every request in io_req_multi_free() is has ->file set. Instead of pointlessly defering and counting reqs with file, dismantle it on place and save for batch dealloc. It also saves us from potentially skipping io_cleanup_req(), put_task(), etc. Never happens though, becacuse ->file is always there. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-28io_uring: remove inflight batching in free_many()Pavel Begunkov
io_free_req_many() is used only for iopoll requests, i.e. reads/writes. Hence no need to batch inflight unhooking. For safety, it'll be done by io_dismantle_req(), which replaces __io_req_aux_free(), and looks more solid and cleaner. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-28io_uring: fix refs underflow in io_iopoll_queue()Pavel Begunkov
Now io_complete_rw_common() puts a ref, extra io_req_put() in io_iopoll_queue() causes undeflow. Remove it. [ 455.998620] refcount_t: underflow; use-after-free. [ 455.998743] WARNING: CPU: 6 PID: 285394 at lib/refcount.c:28 refcount_warn_saturate+0xae/0xf0 [ 455.998772] CPU: 6 PID: 285394 Comm: read-write2 Tainted: G I E 5.8.0-rc2-00048-g1b1aa738f167-dirty #509 [ 455.998772] RIP: 0010:refcount_warn_saturate+0xae/0xf0 ... [ 455.998778] Call Trace: [ 455.998778] io_put_req+0x44/0x50 [ 455.998778] io_iopoll_complete+0x245/0x370 [ 455.998779] io_iopoll_getevents+0x12f/0x1a0 [ 455.998779] io_iopoll_reap_events.part.0+0x5e/0xa0 [ 455.998780] io_ring_ctx_wait_and_kill+0x132/0x1c0 [ 455.998780] io_uring_release+0x20/0x30 [ 455.998780] __fput+0xcd/0x230 [ 455.998781] ____fput+0xe/0x10 [ 455.998781] task_work_run+0x67/0xa0 [ 455.998781] do_exit+0x35d/0xb70 [ 455.998782] do_group_exit+0x43/0xa0 [ 455.998783] get_signal+0x140/0x900 [ 455.998783] do_signal+0x37/0x780 [ 455.998784] __prepare_exit_to_usermode+0x126/0x1c0 [ 455.998785] __syscall_return_slowpath+0x3b/0x1c0 [ 455.998785] do_syscall_64+0x5f/0xa0 [ 455.998785] entry_SYSCALL_64_after_hwframe+0x44/0xa9 Fixes: a1d7c393c47 ("io_uring: enable READ/WRITE to use deferred completions") Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-28io_uring: fix missing io_grab_files()Pavel Begunkov
We won't have valid ring_fd, ring_file in task work. Grab files early. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-28io_uring: don't mark link's head for_asyncPavel Begunkov
No reason to mark a head of a link as for-async in io_req_defer_prep(). grab_env(), etc. That will be done further during submission if neccessary. Mark for_async=false saving extra grab_env() in many cases. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-28io_uring: fix feeding io-wq with uninit reqsPavel Begunkov
io_steal_work() can't be sure that @nxt has req->work properly set, so we can't pass it to io-wq as is. A dirty quick fix -- drag it through io_req_task_queue(), and always return NULL from io_steal_work(). e.g. [ 50.770161] BUG: kernel NULL pointer dereference, address: 00000000 [ 50.770164] #PF: supervisor write access in kernel mode [ 50.770164] #PF: error_code(0x0002) - not-present page [ 50.770168] CPU: 1 PID: 1448 Comm: io_wqe_worker-0 Tainted: G I 5.8.0-rc2-00035-g2237d76530eb-dirty #494 [ 50.770172] RIP: 0010:override_creds+0x19/0x30 ... [ 50.770183] io_worker_handle_work+0x25c/0x430 [ 50.770185] io_wqe_worker+0x2a0/0x350 [ 50.770190] kthread+0x136/0x180 [ 50.770194] ret_from_fork+0x22/0x30 Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-28io_uring: fix punting req w/o grabbed envPavel Begunkov
It's not enough to check for REQ_F_WORK_INITIALIZED and punt async assuming that io_req_work_grab_env() was called, it may not have been. E.g. io_close_prep() and personality path set the flag without further async init. As a quick fix, always pass next work through io_req_task_queue(). Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-28io_uring: fix req->work corruptionPavel Begunkov
req->work and req->task_work are in a union, so io_req_task_queue() screws everything that was in work. De-union them for now. [ 704.367253] BUG: unable to handle page fault for address: ffffffffaf7330d0 [ 704.367256] #PF: supervisor write access in kernel mode [ 704.367256] #PF: error_code(0x0003) - permissions violation [ 704.367261] CPU: 6 PID: 1654 Comm: io_wqe_worker-0 Tainted: G I 5.8.0-rc2-00038-ge28d0bdc4863-dirty #498 [ 704.367265] RIP: 0010:_raw_spin_lock+0x1e/0x36 ... [ 704.367276] __alloc_fd+0x35/0x150 [ 704.367279] __get_unused_fd_flags+0x25/0x30 [ 704.367280] io_openat2+0xcb/0x1b0 [ 704.367283] io_issue_sqe+0x36a/0x1320 [ 704.367294] io_wq_submit_work+0x58/0x160 [ 704.367295] io_worker_handle_work+0x2a3/0x430 [ 704.367296] io_wqe_worker+0x2a0/0x350 [ 704.367301] kthread+0x136/0x180 [ 704.367304] ret_from_fork+0x22/0x30 Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-26io_uring: fix function args for !CONFIG_NETRandy Dunlap
Fix build errors when CONFIG_NET is not set/enabled: ../fs/io_uring.c:5472:10: error: too many arguments to function ‘io_sendmsg’ ../fs/io_uring.c:5474:10: error: too many arguments to function ‘io_send’ ../fs/io_uring.c:5484:10: error: too many arguments to function ‘io_recvmsg’ ../fs/io_uring.c:5486:10: error: too many arguments to function ‘io_recv’ ../fs/io_uring.c:5510:9: error: too many arguments to function ‘io_accept’ ../fs/io_uring.c:5518:9: error: too many arguments to function ‘io_connect’ Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: io-uring@vger.kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-26Merge branch 'io_uring-5.8' into for-5.9/io_uringJens Axboe
Merge in changes that went into 5.8-rc3. GIT will silently do the merge, but we still need a tweak on top of that since io_complete_rw_common() was modified to take a io_comp_state pointer. The auto-merge fails on that, and we end up with something that doesn't compile. * io_uring-5.8: io_uring: fix current->mm NULL dereference on exit io_uring: fix hanging iopoll in case of -EAGAIN io_uring: fix io_sq_thread no schedule when busy Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-26io-wq: return next work from ->do_work() directlyPavel Begunkov
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: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-26io_uring: use task_work for links if possibleJens Axboe
Currently links are always done in an async fashion, unless we catch them inline after we successfully complete a request without having to resort to blocking. This isn't necessarily the most efficient approach, it'd be more ideal if we could just use the task_work handling for this. Outside of saving an async jump, we can also do less prep work for these kinds of requests. Running dependent links from the task_work handler yields some nice performance benefits. As an example, examples/link-cp from the liburing repository uses read+write links to implement a copy operation. Without this patch, the a cache fold 4G file read from a VM runs in about 3 seconds: $ time examples/link-cp /data/file /dev/null real 0m2.986s user 0m0.051s sys 0m2.843s and a subsequent cache hot run looks like this: $ time examples/link-cp /data/file /dev/null real 0m0.898s user 0m0.069s sys 0m0.797s With this patch in place, the cold case takes about 2.4 seconds: $ time examples/link-cp /data/file /dev/null real 0m2.400s user 0m0.020s sys 0m2.366s and the cache hot case looks like this: $ time examples/link-cp /data/file /dev/null real 0m0.676s user 0m0.010s sys 0m0.665s As expected, the (mostly) cache hot case yields the biggest improvement, running about 25% faster with this change, while the cache cold case yields about a 20% increase in performance. Outside of the performance increase, we're using less CPU as well, as we're not using the async offload threads at all for this anymore. Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-25io_uring: enable READ/WRITE to use deferred completionsJens Axboe
A bit more surgery required here, as completions are generally done through the kiocb->ki_complete() callback, even if they complete inline. This enables the regular read/write path to use the io_comp_state logic to batch inline completions. Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-25io_uring: pass in completion state to appropriate issue side handlersJens Axboe
Provide the completion state to the handlers that we know can complete inline, so they can utilize this for batching completions. Cap the max batch count at 32. This should be enough to provide a good amortization of the cost of the lock+commit dance for completions, while still being low enough not to cause any real latency issues for SQPOLL applications. Xuan Zhuo <xuanzhuo@linux.alibaba.com> reports that this changes his profile from: 17.97% [kernel] [k] copy_user_generic_unrolled 13.92% [kernel] [k] io_commit_cqring 11.04% [kernel] [k] __io_cqring_fill_event 10.33% [kernel] [k] udp_recvmsg 5.94% [kernel] [k] skb_release_data 4.31% [kernel] [k] udp_rmem_release 2.68% [kernel] [k] __check_object_size 2.24% [kernel] [k] __slab_free 2.22% [kernel] [k] _raw_spin_lock_bh 2.21% [kernel] [k] kmem_cache_free 2.13% [kernel] [k] free_pcppages_bulk 1.83% [kernel] [k] io_submit_sqes 1.38% [kernel] [k] page_frag_free 1.31% [kernel] [k] inet_recvmsg to 19.99% [kernel] [k] copy_user_generic_unrolled 11.63% [kernel] [k] skb_release_data 9.36% [kernel] [k] udp_rmem_release 8.64% [kernel] [k] udp_recvmsg 6.21% [kernel] [k] __slab_free 4.39% [kernel] [k] __check_object_size 3.64% [kernel] [k] free_pcppages_bulk 2.41% [kernel] [k] kmem_cache_free 2.00% [kernel] [k] io_submit_sqes 1.95% [kernel] [k] page_frag_free 1.54% [kernel] [k] io_put_req [...] 0.07% [kernel] [k] io_commit_cqring 0.44% [kernel] [k] __io_cqring_fill_event Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-25io_uring: pass down completion state on the issue sideJens Axboe
No functional changes in this patch, just in preparation for having the completion state be available on the issue side. Later on, this will allow requests that complete inline to be completed in batches. Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-25io_uring: add 'io_comp_state' to struct io_submit_stateJens Axboe
No functional changes in this patch, just in preparation for passing back pending completions to the caller and completing them in a batched fashion. Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-25io_uring: provide generic io_req_complete() helperJens Axboe
We have lots of callers of: io_cqring_add_event(req, result); io_put_req(req); Provide a helper that does this for us. It helps clean up the code, and also provides a more convenient location for us to change the completion handling. Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-25io_uring: fix NULL-mm for linked reqsPavel Begunkov
__io_queue_sqe() tries to handle all request of a link, so it's not enough to grab mm in io_sq_thread_acquire_mm() based just on the head. Don't check req->needs_mm and do it always. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
2020-06-25io_uring: fix current->mm NULL dereference on exitPavel Begunkov
Don't reissue requests from io_iopoll_reap_events(), the task may not have mm, which ends up with NULL. It's better to kill everything off on exit anyway. [ 677.734670] RIP: 0010:io_iopoll_complete+0x27e/0x630 ... [ 677.734679] Call Trace: [ 677.734695] ? __send_signal+0x1f2/0x420 [ 677.734698] ? _raw_spin_unlock_irqrestore+0x24/0x40 [ 677.734699] ? send_signal+0xf5/0x140 [ 677.734700] io_iopoll_getevents+0x12f/0x1a0 [ 677.734702] io_iopoll_reap_events.part.0+0x5e/0xa0 [ 677.734703] io_ring_ctx_wait_and_kill+0x132/0x1c0 [ 677.734704] io_uring_release+0x20/0x30 [ 677.734706] __fput+0xcd/0x230 [ 677.734707] ____fput+0xe/0x10 [ 677.734709] task_work_run+0x67/0xa0 [ 677.734710] do_exit+0x35d/0xb70 [ 677.734712] do_group_exit+0x43/0xa0 [ 677.734713] get_signal+0x140/0x900 [ 677.734715] do_signal+0x37/0x780 [ 677.734717] ? enqueue_hrtimer+0x41/0xb0 [ 677.734718] ? recalibrate_cpu_khz+0x10/0x10 [ 677.734720] ? ktime_get+0x3e/0xa0 [ 677.734721] ? lapic_next_deadline+0x26/0x30 [ 677.734723] ? tick_program_event+0x4d/0x90 [ 677.734724] ? __hrtimer_get_next_event+0x4d/0x80 [ 677.734726] __prepare_exit_to_usermode+0x126/0x1c0 [ 677.734741] prepare_exit_to_usermode+0x9/0x40 [ 677.734742] idtentry_exit_cond_rcu+0x4c/0x60 [ 677.734743] sysvec_reschedule_ipi+0x92/0x160 [ 677.734744] ? asm_sysvec_reschedule_ipi+0xa/0x20 [ 677.734745] asm_sysvec_reschedule_ipi+0x12/0x20 Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-25io_uring: fix hanging iopoll in case of -EAGAINPavel Begunkov
io_do_iopoll() won't do anything with a request unless req->iopoll_completed is set. So io_complete_rw_iopoll() has to set it, otherwise io_do_iopoll() will poll a file again and again even though the request of interest was completed long time ago. Also, remove -EAGAIN check from io_issue_sqe() as it races with the changed lines. The request will take the long way and be resubmitted from io_iopoll*(). io_kiocb's result and iopoll_completed") Fixes: bbde017a32b3 ("io_uring: add memory barrier to synchronize Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-23io_uring: fix io_sq_thread no schedule when busyXuan Zhuo
When the user consumes and generates sqe at a fast rate, io_sqring_entries can always get sqe, and ret will not be equal to -EBUSY, so that io_sq_thread will never call cond_resched or schedule, and then we will get the following system error prompt: rcu: INFO: rcu_sched self-detected stall on CPU or watchdog: BUG: soft lockup-CPU#23 stuck for 112s! [io_uring-sq:1863] This patch checks whether need to call cond_resched() by checking the need_resched() function every cycle. Suggested-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-21io_uring: kill NULL checks for submit statePavel Begunkov
After recent changes, io_submit_sqes() always passes valid submit state, so kill leftovers checking it for NULL. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-21io_uring: set @poll->file after @poll initPavel Begunkov
It's a good practice to modify fields of a struct after but not before it was initialised. Even though io_init_poll_iocb() doesn't touch poll->file, call it first. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-21io_uring: remove REQ_F_MUST_PUNTPavel Begunkov
REQ_F_MUST_PUNT may seem looking good and clear, but it's the same as not having REQ_F_NOWAIT set. That rather creates more confusion. Moreover, it doesn't even affect any behaviour (e.g. see the patch removing it from io_{read,write}). Kill theg flag and update already outdated comments. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-21io_uring: remove setting REQ_F_MUST_PUNT in rwPavel Begunkov
io_{read,write}() { ... copy_iov: // prep async if (!(flags & REQ_F_NOWAIT) && !file_can_poll(file)) flags |= REQ_F_MUST_PUNT; } REQ_F_MUST_PUNT there is pointless, because if it happens then REQ_F_NOWAIT is known to be _not_ set, and the request will go async path in __io_queue_sqe() anyway. file_can_poll() check is also repeated in arm_poll*(), so don't need it. Remove the mentioned assignment REQ_F_MUST_PUNT in preparation for killing the flag. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-21io_uring: support true async buffered reads, if file provides itJens Axboe
If the file is flagged with FMODE_BUF_RASYNC, then we don't have to punt the buffered read to an io-wq worker. Instead we can rely on page unlocking callbacks to support retry based async IO. This is a lot more efficient than doing async thread offload. The retry is done similarly to how we handle poll based retry. From the unlock callback, we simply queue the retry to a task_work based handler. Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-21io_uring: re-issue block requests that failed because of resourcesJens Axboe
Mark the plug with nowait == true, which will cause requests to avoid blocking on request allocation. If they do, we catch them and reissue them from a task_work based handler. Normally we can catch -EAGAIN directly, but the hard case is for split requests. As an example, the application issues a 512KB request. The block core will split this into 128KB if that's the max size for the device. The first request issues just fine, but we run into -EAGAIN for some latter splits for the same request. As the bio is split, we don't get to see the -EAGAIN until one of the actual reads complete, and hence we cannot handle it inline as part of submission. This does potentially cause re-reads of parts of the range, as the whole request is reissued. There's currently no better way to handle this. Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-21io_uring: catch -EIO from buffered issue request failureJens Axboe
-EIO bubbles up like -EAGAIN if we fail to allocate a request at the lower level. Play it safe and treat it like -EAGAIN in terms of sync retry, to avoid passing back an errant -EIO. Catch some of these early for block based file, as non-mq devices generally do not support NOWAIT. That saves us some overhead by not first trying, then retrying from async context. We can go straight to async punt instead. Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-21io_uring: always plug for any number of IOsJens Axboe
Currently we only plug if we're doing more than two request. We're going to be relying on always having the plug there to pass down information, so plug unconditionally. Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-21io_uring: separate reporting of ring pages from registered pagesBijan Mottahedeh
Ring pages are not pinned so it is more appropriate to report them as locked. Signed-off-by: Bijan Mottahedeh <bijan.mottahedeh@oracle.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-21io_uring: report pinned memory usageBijan Mottahedeh
Report pinned memory usage always, regardless of whether locked memory limit is enforced. Signed-off-by: Bijan Mottahedeh <bijan.mottahedeh@oracle.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-21io_uring: rename ctx->account_mem fieldBijan Mottahedeh
Rename account_mem to limit_name to clarify its purpose. Signed-off-by: Bijan Mottahedeh <bijan.mottahedeh@oracle.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-21io_uring: add wrappers for memory accountingBijan Mottahedeh
Facilitate separation of locked memory usage reporting vs. limiting for upcoming patches. No functional changes. Signed-off-by: Bijan Mottahedeh <bijan.mottahedeh@oracle.com> [axboe: kill unnecessary () around return in io_account_mem()] Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-21io_uring: use EPOLLEXCLUSIVE flag to aoid thundering herd type behaviorJiufei Xue
Applications can pass this flag in to avoid accept thundering herd. Signed-off-by: Jiufei Xue <jiufei.xue@linux.alibaba.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-21io_uring: change the poll type to be 32-bitsJiufei Xue
poll events should be 32-bits to cover EPOLLEXCLUSIVE. Explicit word-swap the poll32_events for big endian to make sure the ABI is not changed. We call this feature IORING_FEAT_POLL_32BITS, applications who want to use EPOLLEXCLUSIVE should check the feature bit first. Signed-off-by: Jiufei Xue <jiufei.xue@linux.alibaba.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
generated by cgit (git 2.34.1) at 2025-09-22 06:37:48 +0000