From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A82C7C433DF for ; Sat, 23 May 2020 01:51:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 886A82072C for ; Sat, 23 May 2020 01:51:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20150623.gappssmtp.com header.i=@kernel-dk.20150623.gappssmtp.com header.b="cuiALyzq" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387477AbgEWBvP (ORCPT ); Fri, 22 May 2020 21:51:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46978 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387461AbgEWBvM (ORCPT ); Fri, 22 May 2020 21:51:12 -0400 Received: from mail-pg1-x543.google.com (mail-pg1-x543.google.com [IPv6:2607:f8b0:4864:20::543]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8BC5CC08C5C4 for ; Fri, 22 May 2020 18:51:11 -0700 (PDT) Received: by mail-pg1-x543.google.com with SMTP id t11so5832666pgg.2 for ; Fri, 22 May 2020 18:51:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=Wd+Rnx5Y+ukW2PvArxihC3mXgVqc6YPFp4BCl1P9bmM=; b=cuiALyzqy5LdaGkggEMKMw8ZCbPYkVsgaGoYkowUv2YSqau1sCJea1+tn9y+FD2jE0 hqs9giU8Mi3LAGZ7Yy4V2tu22HzwH3W81J8+fBe9bvb1GODyDanjB735pb1vgFfx19+c vSLpeyOjo6AaiBKXXUUUCBj5yRXMrOhX4sjADgLdrD6qQfN2X3QnC6PsVLemka9yqxy2 LDVcNP7vH1c4WJIP5GG2T5p+I+bqIcwJAREQ8SkTyyjweJ4KWTvpGe1TR5xjJXMA3Ww4 5K73NgWM8zvy5ZCFXxxXE4JdmpfIlctPbay9J6SCA/1iaFUvCpYuDLZeLP+qDI2bVj7S 4CWg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=Wd+Rnx5Y+ukW2PvArxihC3mXgVqc6YPFp4BCl1P9bmM=; b=X/Gdnps8CkSIYf2mHOKjx3IZ/CAvVw0WfFR5eXw4+uLCPhQHJH7A3afs6AQL0PS1DU sWvW0p2HJtA8GZr6alr+1llFc4Va/83hmwG4NhbhsP8dftLseQaLSHkkICgdiGryTpDP S6RS/winN0LlEAsuQisr5VkrOnpAOFy8lFKCJIgKYNL3zD2aZfmeW8BRH6dl4QglyQc2 WH1XP66JYhhzYwIeOljXD0dsUl+NpgUCxckVp/MUvjsbUE7wjbYIkqFF1+BgKq3ikWiY 46jarOXSFmftNmfZqCHqat6gE5swxkjncdlBQ8JE4Xi13nN40SCuw0TLTss5YsPHdxCN r/Fw== X-Gm-Message-State: AOAM531CFnAQG3GEktNYCAVSElKaXJv27n9gH8IhtiYAhhALvR4vjnBZ zaH+LWQRBlqgCQLyMT/76B7AY3odJKA= X-Google-Smtp-Source: ABdhPJyd+1pCYzGsi2Ok0s0JF7kIgQclUmTGxfhARdgyfgJsfSNYz06K7py8/X/MIRJH7+fbjmCzaw== X-Received: by 2002:aa7:9096:: with SMTP id i22mr6644986pfa.250.1590198671034; Fri, 22 May 2020 18:51:11 -0700 (PDT) Received: from x1.lan ([2605:e000:100e:8c61:e0db:da55:b0a4:601]) by smtp.gmail.com with ESMTPSA id a71sm8255477pje.0.2020.05.22.18.51.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 22 May 2020 18:51:10 -0700 (PDT) From: Jens Axboe To: io-uring@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Jens Axboe Subject: [PATCH 11/11] io_uring: support true async buffered reads, if file provides it Date: Fri, 22 May 2020 19:50:49 -0600 Message-Id: <20200523015049.14808-12-axboe@kernel.dk> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200523015049.14808-1-axboe@kernel.dk> References: <20200523015049.14808-1-axboe@kernel.dk> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- fs/io_uring.c | 102 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 102 insertions(+) diff --git a/fs/io_uring.c b/fs/io_uring.c index e95481c552ff..9eeae10db648 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -498,6 +498,8 @@ struct io_async_rw { struct iovec *iov; ssize_t nr_segs; ssize_t size; + struct wait_page_async wait; + struct callback_head task_work; }; struct io_async_ctx { @@ -2568,6 +2570,102 @@ static int io_read_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe, return 0; } +static void io_async_buf_cancel(struct callback_head *cb) +{ + struct io_async_rw *rw; + struct io_ring_ctx *ctx; + struct io_kiocb *req; + + rw = container_of(cb, struct io_async_rw, task_work); + req = rw->wait.wait.private; + ctx = req->ctx; + + spin_lock_irq(&ctx->completion_lock); + io_cqring_fill_event(req, -ECANCELED); + io_commit_cqring(ctx); + spin_unlock_irq(&ctx->completion_lock); + + io_cqring_ev_posted(ctx); + req_set_fail_links(req); + io_double_put_req(req); +} + +static void io_async_buf_retry(struct callback_head *cb) +{ + struct io_async_rw *rw; + struct io_ring_ctx *ctx; + struct io_kiocb *req; + + rw = container_of(cb, struct io_async_rw, task_work); + req = rw->wait.wait.private; + ctx = req->ctx; + + __set_current_state(TASK_RUNNING); + mutex_lock(&ctx->uring_lock); + __io_queue_sqe(req, NULL); + mutex_unlock(&ctx->uring_lock); +} + +static int io_async_buf_func(struct wait_queue_entry *wait, unsigned mode, + int sync, void *arg) +{ + struct wait_page_async *wp; + struct io_kiocb *req = wait->private; + struct io_async_rw *rw = &req->io->rw; + struct wait_page_key *key = arg; + struct task_struct *tsk; + int ret; + + wp = container_of(wait, struct wait_page_async, wait); + if (wp->key.page != key->page) + return 0; + key->page_match = 1; + if (wp->key.bit_nr != key->bit_nr) + return 0; + if (test_bit(PG_locked, &key->page->flags)) + return -1; + + list_del_init(&wait->entry); + + init_task_work(&rw->task_work, io_async_buf_retry); + /* submit ref gets dropped, acquire a new one */ + refcount_inc(&req->refs); + tsk = req->task; + ret = task_work_add(tsk, &rw->task_work, true); + if (unlikely(ret)) { + /* queue just for cancelation */ + init_task_work(&rw->task_work, io_async_buf_cancel); + tsk = io_wq_get_task(req->ctx->io_wq); + task_work_add(tsk, &rw->task_work, true); + } + wake_up_process(tsk); + return 1; +} + +static bool io_rw_should_retry(struct io_kiocb *req) +{ + struct kiocb *kiocb = &req->rw.kiocb; + int ret; + + /* already tried, or we're doing O_DIRECT */ + if (kiocb->ki_flags & (IOCB_DIRECT | IOCB_WAITQ)) + return false; + /* + * just use poll if we can, and don't attempt if the fs doesn't + * support callback based unlocks + */ + if (file_can_poll(req->file) || !(req->file->f_mode & FMODE_BUF_RASYNC)) + return false; + + ret = kiocb_wait_page_async_init(kiocb, &req->io->rw.wait, + io_async_buf_func, req); + if (ret) + return false; + get_task_struct(current); + req->task = current; + return true; +} + static int io_read(struct io_kiocb *req, bool force_nonblock) { struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs; @@ -2601,6 +2699,7 @@ static int io_read(struct io_kiocb *req, bool force_nonblock) if (!ret) { ssize_t ret2; +retry: if (req->file->f_op->read_iter) ret2 = call_read_iter(req->file, kiocb, &iter); else @@ -2619,6 +2718,9 @@ static int io_read(struct io_kiocb *req, bool force_nonblock) if (!(req->flags & REQ_F_NOWAIT) && !file_can_poll(req->file)) req->flags |= REQ_F_MUST_PUNT; + if (io_rw_should_retry(req)) + goto retry; + kiocb->ki_flags &= ~IOCB_WAITQ; return -EAGAIN; } } -- 2.26.2