From patchwork Tue Dec 15 00:20:19 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Pavel Begunkov X-Patchwork-Id: 344257 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=-10.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, 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 0E39DC4361B for ; Tue, 15 Dec 2020 00:29:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C8F0F22258 for ; Tue, 15 Dec 2020 00:29:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727211AbgLOAYo (ORCPT ); Mon, 14 Dec 2020 19:24:44 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53434 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725976AbgLOAYo (ORCPT ); Mon, 14 Dec 2020 19:24:44 -0500 Received: from mail-wm1-x341.google.com (mail-wm1-x341.google.com [IPv6:2a00:1450:4864:20::341]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 961A6C061793; Mon, 14 Dec 2020 16:24:03 -0800 (PST) Received: by mail-wm1-x341.google.com with SMTP id q75so16855449wme.2; Mon, 14 Dec 2020 16:24:03 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=8jc3AIzkIPReSThseVXRAPm4odmJMoGYu8KGcGUo5xA=; b=UdWHcglApp9RdDZeyVfl7LsJgdxW48tzLbgNRju6ud80NwZdq8pS6rNA48XayxnD2y gxp99ju2U22s0IgeHpYxNkwEmEsSWmjKvkDVgboRjCL0u2BjvWzJuRm3fQuna6NzrVJX tY83rFJle/+8UqxI4cOpq7ZEPwQanA4rNBX48zfg4PVtL5ODTFYQfgYr+oKNqJ85Y/gd 599roSuL8vkZuUsB+DMvesJq5/Qay+HaVljVBmkn57M9MaFlDCjvpgkaWPWHAqXbqbH5 awkn32y9RHX7Bg8npAuH4ig4MoKopNAyVbodgQEudUlOhmPl/5BfCRzLw7S/Tb6KT7TR Av8A== 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:mime-version :content-transfer-encoding; bh=8jc3AIzkIPReSThseVXRAPm4odmJMoGYu8KGcGUo5xA=; b=JjH7Xp3ZjrUPqt0bm0f52mOdf+VEv41WWJNFd5zZmerIWueDZ4ud/4wCS4AHQn//KP yz7xTY1dr+tIjnd+qTmFJ3C8nmB3UamvlZyBkQqVebySh2wZ7ewMbhPSKjjTN2EbMXMm pkC+c6B1isPYgjQ+jgRfaH7J1mErUMrdZm4DAm6L3PzHI5i73sKrY0tNM94kJ21aQudX 2X8qjebGo3JUPuKZCgEGC7yLidNoK82iGc5aof7gyDw7T7mtssCSujCHcaBFbXw5zbef DS0ix2m5rk6/U7dFwwfw66FJlxh4HHAiJlOkZrAUc6Rnyv0gvC0RpdiRGewsAWPI9Ett +nVQ== X-Gm-Message-State: AOAM531NvqE4EFF++ZUDnUIa/hgiy0BnypCXAdurAe2lnojwulERxGBs wUMdrDWQkqSSQVRaFCw/5r8V+SagMKvQzKLc X-Google-Smtp-Source: ABdhPJwGNnrKGp65JFv4dDtyk0FguiKKzh1xTxkYj/G+sMLant4a7Rnm4MCbD8CKdIpwjoDGsmxiog== X-Received: by 2002:a05:600c:258:: with SMTP id 24mr30918877wmj.16.1607991842015; Mon, 14 Dec 2020 16:24:02 -0800 (PST) Received: from localhost.localdomain ([85.255.232.163]) by smtp.gmail.com with ESMTPSA id b19sm5362012wmj.37.2020.12.14.16.24.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 14 Dec 2020 16:24:01 -0800 (PST) From: Pavel Begunkov To: linux-block@vger.kernel.org Cc: Jens Axboe , Christoph Hellwig , Matthew Wilcox , Ming Lei , Johannes Weiner , Alexander Viro , "Darrick J . Wong" , "Martin K . Petersen" , Jonathan Corbet , linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, io-uring@vger.kernel.org, linux-kernel@vger.kernel.org, target-devel@vger.kernel.org, linux-scsi@vger.kernel.org, linux-doc@vger.kernel.org Subject: [PATCH v1 0/6] no-copy bvec Date: Tue, 15 Dec 2020 00:20:19 +0000 Message-Id: X-Mailer: git-send-email 2.24.0 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org Instead of creating a full copy of iter->bvec into bio in direct I/O, the patchset makes use of the one provided. It changes semantics and obliges users of asynchronous kiocb to track bvec lifetime, and [1/6] converts the only place that doesn't. bio_iov_iter_get_pages() is still does iov_iter_advance(), which is not great, but neccessary for revert to work. It's desirable to have a fast version of iov_iter_advance(i, i->count), so we may want to hack something up for that. E.g. allow to not keep it consistent in some cases when i->count==0. Also we can add a separate bio pool without inlined bvec. Very easy to do and shrinks bios from 3 to 2 cachelines. Also as suggested it removes BIO_WORKINGSET from direct paths: blkdev, iomap, fs/direct-io. Even though the last one is not very important as more filesystems are converted to iomap, but still looks hacky. Maybe, as Johannes mentioned in another thread, moving it to the writeback code (or other option) would be better in the end. Afterwards? since RFC: - add target_core_file patch by Christoph - make no-copy default behaviour, remove iter flag - iter_advance() instead of hacks to revert to work - add bvec iter_advance() optimisation patch - remove PSI annotations from direct IO (iomap, block and fs/direct) - note in d/f/porting Christoph Hellwig (1): target/file: allocate the bvec array as part of struct target_core_file_cmd Pavel Begunkov (5): iov_iter: optimise bvec iov_iter_advance() bio: deduplicate adding a page into bio block/psi: remove PSI annotations from direct IO bio: add a helper calculating nr segments to alloc block/iomap: don't copy bvec for direct IO Documentation/filesystems/porting.rst | 9 +++ block/bio.c | 103 ++++++++++++-------------- drivers/target/target_core_file.c | 20 ++--- fs/block_dev.c | 7 +- fs/direct-io.c | 2 + fs/iomap/direct-io.c | 9 +-- include/linux/bio.h | 9 +++ lib/iov_iter.c | 19 +++++ 8 files changed, 102 insertions(+), 76 deletions(-)