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=-6.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_GIT autolearn=no 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 9387EC4167B for ; Thu, 10 Dec 2020 20:02:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4BAB322E01 for ; Thu, 10 Dec 2020 20:02:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404535AbgLJUCI (ORCPT ); Thu, 10 Dec 2020 15:02:08 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56156 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404302AbgLJUCC (ORCPT ); Thu, 10 Dec 2020 15:02:02 -0500 Received: from mail-io1-xd2f.google.com (mail-io1-xd2f.google.com [IPv6:2607:f8b0:4864:20::d2f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BC24DC0613CF for ; Thu, 10 Dec 2020 12:01:21 -0800 (PST) Received: by mail-io1-xd2f.google.com with SMTP id n14so6855032iom.10 for ; Thu, 10 Dec 2020 12:01:21 -0800 (PST) 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:mime-version :content-transfer-encoding; bh=Sya1PQtNgFqGm2aTT6RKY27a2ojJW0x9lC7904ZSiEE=; b=YutlIAu/AqhNz+Bu/8aUeVIh1Wc5bHqGk6HIgREMorxFYmf5MrEWhU0MkW3PiefvV7 PdVwCMd8nmOQzpWxTKqeHhn3gIWb19QmxbUoAqb+Tg7uTH0FACDVCUDZNI1AaRY0Dx0K fy3IYCzZobSZ6IIt0d2LBvs7Npd83LF8yXB6Zsp/4StujyDwmWMzXsVdE4lsncnhibmJ ZrxFVSoyR4yDZ9mx57r0pjRwxNlmTe4lWYWOcXNCiA9+gTRLjnu01AocqjVdQYNHwkiX 8uXrY6AB2CQEH/xq09GwBh75dCrrUUy+q3pM/hEsqwDVOd8F3Dl9vjtoo7i5WqKCOVoZ D4tQ== 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=Sya1PQtNgFqGm2aTT6RKY27a2ojJW0x9lC7904ZSiEE=; b=rds+yjrop7z0J4oAnxefgl346c4skzSCAlUodmXqRwe1fGnERjParIK4W2awJ+zWAx pRS8EhKVl1bHXAuazz9L/UA8uVMjzDrSnoeZN516v268F5N2Zava19ZB7YBEvDtjrZSr K7u8UakGUN60Kik71BLzVp372nOOywjdboDsfzRzW90i+lmCaq1jsspFhOfZ4g8n2bSU OJVDxgkUCD5UdsUr59rilXAoqaz4PSja7l5DPY8FJ7M4JJSmE8LbqU8Gy+BfV876AWrG VS2x6/j3mXCp5/BrpszXFgY7aVYDXaSSqYW+9OQSPSBbQlhA7CeknEnyWH1/1bp5eyPt tD/g== X-Gm-Message-State: AOAM533jXEPeFTDUBFBu1PbvBZs0rZ59UsQrZiitlIC/ZEiTx9Sg3oyT JKBXWOjvRZm7Qjvt0ky89bumae+Vdz0xHg== X-Google-Smtp-Source: ABdhPJzdzL3VIXkpHz7bQynuWQjxGeErRYapwHFROBwy7jSEFISUfgh21sMZOTrKlwdshtBSl9NmrA== X-Received: by 2002:a5d:9a03:: with SMTP id s3mr10246605iol.20.1607630480653; Thu, 10 Dec 2020 12:01:20 -0800 (PST) Received: from p1.localdomain ([65.144.74.34]) by smtp.gmail.com with ESMTPSA id x5sm3850277ilm.22.2020.12.10.12.01.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 10 Dec 2020 12:01:20 -0800 (PST) From: Jens Axboe To: linux-fsdevel@vger.kernel.org Cc: torvalds@linux-foundation.org, viro@zeniv.linux.org.uk Subject: [PATCHSET 0/2] fs: Support for LOOKUP_NONBLOCK / RESOLVE_NONBLOCK Date: Thu, 10 Dec 2020 13:01:12 -0700 Message-Id: <20201210200114.525026-1-axboe@kernel.dk> X-Mailer: git-send-email 2.29.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Hi, This adds support for just doing the RCU based (and non-blocking) part of path resolution. The main motivation is for io_uring to be able to do saner/faster open, so we don't always have to go async, particularly for the fast path of the data already being cached. Internally that is presented as LOOKUP_NONBLOCK, which depends on LOOKUP_RCU for doing the right thing. If we terminate the RCU part of the lookup, then we return -EAGAIN if LOOKUP_NONBLOCK is also set. The second patch is enabling this through openat2() as well, by adding a RESOLVE_NONBLOCK that can be passed in struct open_how ->resolve as well. Basic test case: [root@archlinux liburing]# echo 3 > /proc/sys/vm/drop_caches [root@archlinux liburing]# test/do-open2 /etc/nanorc open: -1 openat2: Resource temporarily unavailable [root@archlinux liburing]# touch /etc/nanorc [root@archlinux liburing]# test/do-open2 /etc/nanorc open: 3 -- Jens Axboe