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=-6.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS 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 63E0BC00449 for ; Fri, 5 Oct 2018 08:39:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1170D20875 for ; Fri, 5 Oct 2018 08:39:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="NjPTp6Za" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1170D20875 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-btrfs-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728481AbeJEPhS (ORCPT ); Fri, 5 Oct 2018 11:37:18 -0400 Received: from mail-yw1-f67.google.com ([209.85.161.67]:35135 "EHLO mail-yw1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728072AbeJEPhS (ORCPT ); Fri, 5 Oct 2018 11:37:18 -0400 Received: by mail-yw1-f67.google.com with SMTP id y76-v6so4938020ywd.2; Fri, 05 Oct 2018 01:39:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=/fu/BTydMXzRWN2CrdV31OzloX1CkvgJoxVjiOoyqyM=; b=NjPTp6Za/WgiigIh/Ti9SWRU3QV5k0piZ54NHY19P0hfQhjU7diqTnc7m0LNkb1scF f1XI8M3xVYPJOeDwtdxpzxUXkRNLoVhdfiYimChokAXVzwGr9Quelo92rSS7MlFGxTrH Nqncfwkc82MVgiJaq3zEED/LvXT2+IkoPRulOUv6UGLQgWp/NukWe/iS09L2X+jhRkaW jtvYy6PY5eRc91saUcVQPA8tYbG/V+VyWFwSkGgj81/HjgJqVQIx4euLxUSl/OHIwat2 TZN/UA+ZLtJ9xphlGgJMax+VSbX8uxxt9grZqQs56Z6nzGKVeUd/wQBmeLj4BroxL4qh 7nJg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=/fu/BTydMXzRWN2CrdV31OzloX1CkvgJoxVjiOoyqyM=; b=ho2oiXtQt0+FPxHfGfAwda1n4Kt4ZEeIPIXY037geYTHL6TJIZrMlVSrJBvl+wZi7k wVz1LlWLwdGCLqp2pJpCKHVXFmsWze6EQDIhOR1ein+TB3g8uFQq9+6lAhdfc8MP/2S+ YMTMWt8Q6ptWcVdIzyDGLVh2eFfkkegbVLUv25STkWGHAHdDXp0qvQAA/2jW41zgJK8H cFfsiSHFP4cNEEGaSRfU+cP1MMJNIG4XwOmMcAxlDEGGxbgGnwxj9RBUns4KIdSjb9zy C5OvRAM7e/VfB0dqAuriW7vdhIeKbtoIOHWjPf7uCgp3fwHs2AKeDlhH3jCMJGhfxSxv vaaw== X-Gm-Message-State: ABuFfojs8F5+NAHdbnL8WyGY245Vh/9FN+QEKBkotQ5Vzy6nn/ELkulW C5Ce8PKErn7/KaVaL/1NJNeArsqWzN2WqK6gT0c= X-Google-Smtp-Source: ACcGV63BSdyUuq3ufP+fWrI0JwMlh1uMdlX9gsfJPWPsmpKILHbK6W1rWTui9qVYTcRV68KKJR4PU/jHyoZGfK2dE9E= X-Received: by 2002:a0d:c947:: with SMTP id l68-v6mr5678893ywd.404.1538728775837; Fri, 05 Oct 2018 01:39:35 -0700 (PDT) MIME-Version: 1.0 References: <153870027422.29072.7433543674436957232.stgit@magnolia> <153870032167.29072.11158511021942868400.stgit@magnolia> In-Reply-To: <153870032167.29072.11158511021942868400.stgit@magnolia> From: Amir Goldstein Date: Fri, 5 Oct 2018 11:39:24 +0300 Message-ID: Subject: Re: [PATCH 07/15] vfs: skip zero-length dedupe requests To: "Darrick J. Wong" Cc: Dave Chinner , linux-xfs , linux-fsdevel , Linux Btrfs , ocfs2-devel@oss.oracle.com, Eric Sandeen Content-Type: text/plain; charset="UTF-8" Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Fri, Oct 5, 2018 at 3:46 AM Darrick J. Wong wrote: > > From: Darrick J. Wong > > Don't bother calling the filesystem for a zero-length dedupe request; > we can return zero and exit. > > Signed-off-by: Darrick J. Wong > --- > fs/read_write.c | 5 +++++ > 1 file changed, 5 insertions(+) > > > diff --git a/fs/read_write.c b/fs/read_write.c > index 973d3da78c09..99b2f809180c 100644 > --- a/fs/read_write.c > +++ b/fs/read_write.c > @@ -1966,6 +1966,11 @@ int vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos, > if (!dst_file->f_op->dedupe_file_range) > goto out_drop_write; > > + if (len == 0) { > + ret = 0; > + goto out_drop_write; > + } > + > ret = dst_file->f_op->dedupe_file_range(src_file, src_pos, > dst_file, dst_pos, len); I suppose it is best to let user get the same errors he would get before this change rather than skipping zero length copy at vfs_dedupe_file_range() level, so looks fine. Thanks, Amir.