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=-10.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 948BCC4361B for ; Wed, 16 Dec 2020 03:32:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5784623130 for ; Wed, 16 Dec 2020 03:32:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725287AbgLPDc5 (ORCPT ); Tue, 15 Dec 2020 22:32:57 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51990 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725274AbgLPDc4 (ORCPT ); Tue, 15 Dec 2020 22:32:56 -0500 Received: from mail-pf1-x442.google.com (mail-pf1-x442.google.com [IPv6:2607:f8b0:4864:20::442]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B5A83C0613D6 for ; Tue, 15 Dec 2020 19:32:16 -0800 (PST) Received: by mail-pf1-x442.google.com with SMTP id 131so15731074pfb.9 for ; Tue, 15 Dec 2020 19:32:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=veVIVNk8PAyV7iFAehCsxwGquHtPF8HwrxYnNlbnzbE=; b=IjhBM44BVrVbSUPbn4roZtsCN9KLZ2gsFzzBxTZHrPDEXt+bAEZUexAopItMZzgH7k 4RJOl38q3UQQ/RE+hHdIqdXgEGBX/EmQy6HMB7xjAsNoyVzqdG4pq+wlfHNIPWvfSnAH 3h04j8vRniV5dQsCGgB/aiiccaDvvHiBczEeLNCv5m4wSSq6Tj3S8YvxGKfwcTIpRh77 be5mnJvpSLpQKiD4mIAwsxJ1pB3eaJqY2eqUx8WJRsduG7VDR+rEseKWBK1QVsgfZhsg dvCZnQGdOD1y7Q7b24FB5YunHgmbws11y4IOZEixxlHW/peytbmcoQByWcjUSBW+1sVA 0vjw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=veVIVNk8PAyV7iFAehCsxwGquHtPF8HwrxYnNlbnzbE=; b=PSpnuiZ1wOVuF+wcTdX0Z2AALXop3J68gZqUByd3lrnaIbz669YW9G50SlpvjLWep2 5Q8SIrkhbFwdHgMhY7Q4Latk5jWuEXfgCmqsLtg+fnzWOv2PH4SdjCIDWHmMQ/CTKZEl /81TrXDsacMcvQeoylTKvaWlrMaXeRvRfodZh5dl3cG9zj5B6GxLVlEhrXF6m7CYAWOx 3PTvHDXinb34hgXgLw6J1MYjQtRvY08FFg+R8HthnRQ5FVTL7wUASTezXPwM0K2MTdcI 4CI6nZSAPz13Eicgke4s3mI1SCKLVFZA0v++d+DNohKAa0NZw5xhRr5HjM2NiJ7LHxL5 w2Yw== X-Gm-Message-State: AOAM530ulsrHYKt2jwuEfRybBFQDbveoiO17s9wFjMpKWrzJdeBtFOSH a0fTIiwGu+6jvny7TJR431vOnt9iw5dyIA== X-Google-Smtp-Source: ABdhPJy7qQ5Y0Te64D7iValNux9aU0UPsCb74DNWrM5bD1QoIc7dUAI3R1Mv89VzCbQxpEQ0Vp8JOw== X-Received: by 2002:a63:1a02:: with SMTP id a2mr30983184pga.359.1608089536315; Tue, 15 Dec 2020 19:32:16 -0800 (PST) Received: from [192.168.1.134] ([66.219.217.173]) by smtp.gmail.com with ESMTPSA id n28sm463895pfq.61.2020.12.15.19.32.14 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 15 Dec 2020 19:32:15 -0800 (PST) Subject: Re: [PATCH 2/4] fs: add support for LOOKUP_NONBLOCK To: Al Viro Cc: linux-fsdevel@vger.kernel.org, torvalds@linux-foundation.org References: <20201214191323.173773-1-axboe@kernel.dk> <20201214191323.173773-3-axboe@kernel.dk> <20201216024315.GJ3579531@ZenIV.linux.org.uk> From: Jens Axboe Message-ID: Date: Tue, 15 Dec 2020 20:32:14 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20201216024315.GJ3579531@ZenIV.linux.org.uk> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 12/15/20 7:43 PM, Al Viro wrote: > On Mon, Dec 14, 2020 at 12:13:22PM -0700, Jens Axboe wrote: >> @@ -3140,6 +3149,12 @@ static const char *open_last_lookups(struct nameidata *nd, >> return ERR_CAST(dentry); >> if (likely(dentry)) >> goto finish_lookup; >> + /* >> + * We can't guarantee nonblocking semantics beyond this, if >> + * the fast lookup fails. >> + */ >> + if (nd->flags & LOOKUP_NONBLOCK) >> + return ERR_PTR(-EAGAIN); >> >> BUG_ON(nd->flags & LOOKUP_RCU); > > That can't be right - we already must have removed LOOKUP_RCU here > (see BUG_ON() right after that point). What is that test supposed > to catch? > > What am I missing here? Nothing I think, doesn't look like it's needed. If we don't return a valid dentry under LOOKUP_RCU, we will indeed have unlazied at this point. So this hunk can go. -- Jens Axboe