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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 D9408C433E0 for ; Sat, 26 Dec 2020 17:59:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A84F72082D for ; Sat, 26 Dec 2020 17:59:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726327AbgLZR6p (ORCPT ); Sat, 26 Dec 2020 12:58:45 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48992 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726194AbgLZR6p (ORCPT ); Sat, 26 Dec 2020 12:58:45 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E4AD8C0613C1 for ; Sat, 26 Dec 2020 09:58:04 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=5jiMr/lyn6lvkRlFqUo8QdAXYN+UYKROrmXOMsSa8zA=; b=oHAjQpbkvDodhU/LPildFsD2MI U8BkdeHPn8gI7vOSZfKjgStVFL66I/R0HuzAv5no24ShUWy0F5RA+ZAlJCoftWOa+HWnVILEt/3wQ JguG1QdG3Effq3pzGhy3P4buLxCAPXSGZdrZ97X3BaVtfPu8oEhr2zj75YORCTphV5c2nGvXuboVy TtzIu0Ndau/JkB7eFSulY7BWcBweSLNeFA+d0GH9vO4zCaUbYcGiM8BtM0m2nWy/yU81Ofb4EotPS ZFpi3LUjH6p8oAmtgV5ufn56ZcUyA8bu9haam3HRyoK8HrbwiZvyAUXI8ltgA/kSHvYCtR78s+MW3 cv3DMxSg==; Received: from willy by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1ktDpJ-0000tm-UE; Sat, 26 Dec 2020 17:58:02 +0000 Date: Sat, 26 Dec 2020 17:58:01 +0000 From: Matthew Wilcox To: Jens Axboe Cc: Al Viro , linux-fsdevel@vger.kernel.org, torvalds@linux-foundation.org Subject: Re: [PATCH 1/4] fs: make unlazy_walk() error handling consistent Message-ID: <20201226175801.GV874@casper.infradead.org> References: <20201217161911.743222-1-axboe@kernel.dk> <20201217161911.743222-2-axboe@kernel.dk> <66d1d322-42d4-5a46-05fb-caab31d0d834@kernel.dk> <20201226045043.GA3579531@ZenIV.linux.org.uk> <9ce193e7-8609-7d96-4719-f1b316c927e6@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9ce193e7-8609-7d96-4719-f1b316c927e6@kernel.dk> Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Sat, Dec 26, 2020 at 10:33:25AM -0700, Jens Axboe wrote: > +.TP > +.B RESOLVE_CACHED > +Make the open operation fail unless all path components are already present > +in the kernels lookup cache. > +If any kind of revalidation or IO is needed to satisfy the lookup, Usually spelled I/O in manpages. > +.BR openat2 () > +fails with the error > +.B EAGAIN. > +This is useful in providing a fast path open that can be performed without > +resorting to thread offload, or other mechanism that an application might > +use to offload slower operations. That almost reads backwards ... how about this? This provides a fast path open that can be used when an application does not wish to block. It allows the application to hand off the lookup to a separate thread which can block.