From patchwork Thu Jun 18 14:43:44 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jens Axboe X-Patchwork-Id: 11612377 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 48DAE159A for ; Thu, 18 Jun 2020 14:46:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2A01220890 for ; Thu, 18 Jun 2020 14:46:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=kernel-dk.20150623.gappssmtp.com header.i=@kernel-dk.20150623.gappssmtp.com header.b="veVE78EJ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731186AbgFROqT (ORCPT ); Thu, 18 Jun 2020 10:46:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57366 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726478AbgFROoF (ORCPT ); Thu, 18 Jun 2020 10:44:05 -0400 Received: from mail-pf1-x443.google.com (mail-pf1-x443.google.com [IPv6:2607:f8b0:4864:20::443]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 86A12C061794 for ; Thu, 18 Jun 2020 07:44:05 -0700 (PDT) Received: by mail-pf1-x443.google.com with SMTP id h185so2895584pfg.2 for ; Thu, 18 Jun 2020 07:44:05 -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:reply-to :mime-version:content-transfer-encoding; bh=tVJM5ezTdcIMG+aKDW1osETe1l5d87INy1YG0FUdQcM=; b=veVE78EJYXVACUi1db6AgzNJIzh1hHgYOEDwJ41A29iyHkJ0tRhmtt2MLXV57P+t9T huAegqWFdBcpK4nimSirWfSC0b9sPD6lnc/YrwOmnptgxWF7i9cd+CEONozpAruie+nd wPqh4hcqGMRiDgDp72UNJ9uJRJ3Tm6xYgQAXv7jwxFhQBMol00k7MbnVC0E69rPw6FIM 7UKG7C5tnxjAntploc2dKWqJuB+isxJpInUjNRMdqtbp8QrgmRcJRGjgnIdC2OqwERSf xgxD3JLAUc+AU3m+cc8OrVO8os02InMtoRgHoCVgMKC/eW5Z+iV6e3xMpQFkEs3n9M84 vhKg== 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:reply-to:mime-version:content-transfer-encoding; bh=tVJM5ezTdcIMG+aKDW1osETe1l5d87INy1YG0FUdQcM=; b=DengvcEFfpnjO2LTdApox/DbyFfbqEHFNblzBlJ2yCQElOQvUavqZLLENo2+wgS20Y uQ+DMZHWhAhYV/i7byiJlnSdUIeBBBQo9RKbnjTnKWtKp2+WJZl5ZtuyEuDw5jG9WKUo anXZd5tiR0/gzbgKF3M+DGsDVKXcIG8sBNTmbBTqvRRlDLvtCklrGL7zupVG7VsVa5lz v/+/6oLBQ8kD+njBpfFze92ADVw9iNe/Ug2xsUs/ZUrDut6Tu63uzaKw0vap0gMta/v3 4EkjxkR57LQsRasnyiCvb6Jn+WjtnU3yqCPFcMDpGt7Xy2Zjl7hAHCHlMxhnVznrzzKF 9PkQ== X-Gm-Message-State: AOAM532uWNGWkLrFeg+ffjODQhezPCVTwBwNNNEVunTWU3uJGHfB+1GX 65tR7mVAcqOzz9p1EA2PgAR8Kw== X-Google-Smtp-Source: ABdhPJybozkuJOyPuS+aF/bntPw1nY8EdCmOZ0hRiMVA9zO7UZT6xbjz8eMsCaZwMXp2bvsabGcJ4A== X-Received: by 2002:aa7:9537:: with SMTP id c23mr3848900pfp.149.1592491444963; Thu, 18 Jun 2020 07:44:04 -0700 (PDT) Received: from x1.localdomain ([65.144.74.34]) by smtp.gmail.com with ESMTPSA id g9sm3127197pfm.151.2020.06.18.07.44.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 18 Jun 2020 07:44:04 -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, akpm@linux-foundation.org, Jens Axboe Subject: [PATCH 04/15] io_uring: re-issue block requests that failed because of resources Date: Thu, 18 Jun 2020 08:43:44 -0600 Message-Id: <20200618144355.17324-5-axboe@kernel.dk> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200618144355.17324-1-axboe@kernel.dk> References: <20200618144355.17324-1-axboe@kernel.dk> Reply-To: "[PATCHSET v7 0/15]"@vger.kernel.org, Add@vger.kernel.org, support@vger.kernel.org, for@vger.kernel.org, async@vger.kernel.org, buffered@vger.kernel.org, reads@vger.kernel.org MIME-Version: 1.0 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org 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 --- fs/io_uring.c | 148 ++++++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 124 insertions(+), 24 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index 2e257c5a1866..40413fb9d07b 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -900,6 +900,13 @@ static int io_file_get(struct io_submit_state *state, struct io_kiocb *req, static void __io_queue_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe); +static ssize_t io_import_iovec(int rw, struct io_kiocb *req, + struct iovec **iovec, struct iov_iter *iter, + bool needs_lock); +static int io_setup_async_rw(struct io_kiocb *req, ssize_t io_size, + struct iovec *iovec, struct iovec *fast_iov, + struct iov_iter *iter); + static struct kmem_cache *req_cachep; static const struct file_operations io_uring_fops; @@ -1978,12 +1985,115 @@ static void io_complete_rw_common(struct kiocb *kiocb, long res) __io_cqring_add_event(req, res, cflags); } +static void io_sq_thread_drop_mm(struct io_ring_ctx *ctx) +{ + struct mm_struct *mm = current->mm; + + if (mm) { + kthread_unuse_mm(mm); + mmput(mm); + } +} + +static int io_sq_thread_acquire_mm(struct io_ring_ctx *ctx, + struct io_kiocb *req) +{ + if (io_op_defs[req->opcode].needs_mm && !current->mm) { + if (unlikely(!mmget_not_zero(ctx->sqo_mm))) + return -EFAULT; + kthread_use_mm(ctx->sqo_mm); + } + + return 0; +} + +#ifdef CONFIG_BLOCK +static bool io_resubmit_prep(struct io_kiocb *req, int error) +{ + struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs; + ssize_t ret = -ECANCELED; + struct iov_iter iter; + int rw; + + if (error) { + ret = error; + goto end_req; + } + + switch (req->opcode) { + case IORING_OP_READV: + case IORING_OP_READ_FIXED: + case IORING_OP_READ: + rw = READ; + break; + case IORING_OP_WRITEV: + case IORING_OP_WRITE_FIXED: + case IORING_OP_WRITE: + rw = WRITE; + break; + default: + printk_once(KERN_WARNING "io_uring: bad opcode in resubmit %d\n", + req->opcode); + goto end_req; + } + + ret = io_import_iovec(rw, req, &iovec, &iter, false); + if (ret < 0) + goto end_req; + ret = io_setup_async_rw(req, ret, iovec, inline_vecs, &iter); + if (!ret) + return true; + kfree(iovec); +end_req: + io_cqring_add_event(req, ret); + req_set_fail_links(req); + io_put_req(req); + return false; +} + +static void io_rw_resubmit(struct callback_head *cb) +{ + struct io_kiocb *req = container_of(cb, struct io_kiocb, task_work); + struct io_ring_ctx *ctx = req->ctx; + int err; + + __set_current_state(TASK_RUNNING); + + err = io_sq_thread_acquire_mm(ctx, req); + + if (io_resubmit_prep(req, err)) { + refcount_inc(&req->refs); + io_queue_async_work(req); + } +} +#endif + +static bool io_rw_reissue(struct io_kiocb *req, long res) +{ +#ifdef CONFIG_BLOCK + struct task_struct *tsk; + int ret; + + if ((res != -EAGAIN && res != -EOPNOTSUPP) || io_wq_current_is_worker()) + return false; + + tsk = req->task; + init_task_work(&req->task_work, io_rw_resubmit); + ret = task_work_add(tsk, &req->task_work, true); + if (!ret) + return true; +#endif + return false; +} + static void io_complete_rw(struct kiocb *kiocb, long res, long res2) { struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw.kiocb); - io_complete_rw_common(kiocb, res); - io_put_req(req); + if (!io_rw_reissue(req, res)) { + io_complete_rw_common(kiocb, res); + io_put_req(req); + } } static void io_complete_rw_iopoll(struct kiocb *kiocb, long res, long res2) @@ -2169,6 +2279,9 @@ static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe, if (kiocb->ki_flags & IOCB_NOWAIT) req->flags |= REQ_F_NOWAIT; + if (kiocb->ki_flags & IOCB_DIRECT) + io_get_req_task(req); + if (force_nonblock) kiocb->ki_flags |= IOCB_NOWAIT; @@ -2668,6 +2781,7 @@ static int io_read(struct io_kiocb *req, bool force_nonblock) iov_count = iov_iter_count(&iter); ret = rw_verify_area(READ, req->file, &kiocb->ki_pos, iov_count); if (!ret) { + unsigned long nr_segs = iter.nr_segs; ssize_t ret2 = 0; if (req->file->f_op->read_iter) @@ -2679,6 +2793,8 @@ static int io_read(struct io_kiocb *req, bool force_nonblock) if (!force_nonblock || (ret2 != -EAGAIN && ret2 != -EIO)) { kiocb_done(kiocb, ret2); } else { + iter.count = iov_count; + iter.nr_segs = nr_segs; copy_iov: ret = io_setup_async_rw(req, io_size, iovec, inline_vecs, &iter); @@ -2765,6 +2881,7 @@ static int io_write(struct io_kiocb *req, bool force_nonblock) iov_count = iov_iter_count(&iter); ret = rw_verify_area(WRITE, req->file, &kiocb->ki_pos, iov_count); if (!ret) { + unsigned long nr_segs = iter.nr_segs; ssize_t ret2; /* @@ -2802,6 +2919,8 @@ static int io_write(struct io_kiocb *req, bool force_nonblock) if (!force_nonblock || ret2 != -EAGAIN) { kiocb_done(kiocb, ret2); } else { + iter.count = iov_count; + iter.nr_segs = nr_segs; copy_iov: ret = io_setup_async_rw(req, io_size, iovec, inline_vecs, &iter); @@ -4282,28 +4401,6 @@ static void io_async_queue_proc(struct file *file, struct wait_queue_head *head, __io_queue_proc(&pt->req->apoll->poll, pt, head); } -static void io_sq_thread_drop_mm(struct io_ring_ctx *ctx) -{ - struct mm_struct *mm = current->mm; - - if (mm) { - kthread_unuse_mm(mm); - mmput(mm); - } -} - -static int io_sq_thread_acquire_mm(struct io_ring_ctx *ctx, - struct io_kiocb *req) -{ - if (io_op_defs[req->opcode].needs_mm && !current->mm) { - if (unlikely(!mmget_not_zero(ctx->sqo_mm))) - return -EFAULT; - kthread_use_mm(ctx->sqo_mm); - } - - return 0; -} - static void io_async_task_func(struct callback_head *cb) { struct io_kiocb *req = container_of(cb, struct io_kiocb, task_work); @@ -5814,6 +5911,9 @@ static void io_submit_state_start(struct io_submit_state *state, unsigned int max_ios) { blk_start_plug(&state->plug); +#ifdef CONFIG_BLOCK + state->plug.nowait = true; +#endif state->free_reqs = 0; state->file = NULL; state->ios_left = max_ios;