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=-15.4 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 E7D2BC433E6 for ; Tue, 19 Jan 2021 01:05:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 650F122D6D for ; Tue, 19 Jan 2021 01:05:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732898AbhASBFD (ORCPT ); Mon, 18 Jan 2021 20:05:03 -0500 Received: from mail-1.ca.inter.net ([208.85.220.69]:46116 "EHLO mail-1.ca.inter.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732238AbhASBFD (ORCPT ); Mon, 18 Jan 2021 20:05:03 -0500 Received: from localhost (offload-3.ca.inter.net [208.85.220.70]) by mail-1.ca.inter.net (Postfix) with ESMTP id 5895E2EA058; Mon, 18 Jan 2021 20:04:21 -0500 (EST) Received: from mail-1.ca.inter.net ([208.85.220.69]) by localhost (offload-3.ca.inter.net [208.85.220.70]) (amavisd-new, port 10024) with ESMTP id YDJ1pjI18RLg; Mon, 18 Jan 2021 19:50:44 -0500 (EST) Received: from [192.168.48.23] (host-104-157-204-209.dyn.295.ca [104.157.204.209]) (using TLSv1 with cipher DHE-RSA-AES128-SHA (128/128 bits)) (No client certificate requested) (Authenticated sender: dgilbert@interlog.com) by mail-1.ca.inter.net (Postfix) with ESMTPSA id A39982EA02A; Mon, 18 Jan 2021 20:04:20 -0500 (EST) Reply-To: dgilbert@interlog.com Subject: Re: [PATCH v6 3/4] scatterlist: add sgl_compare_sgl() function To: David Disseldorp Cc: linux-scsi@vger.kernel.org, linux-block@vger.kernel.org, target-devel@vger.kernel.org, linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org, martin.petersen@oracle.com, jejb@linux.vnet.ibm.com, bostroesser@gmail.com, bvanassche@acm.org, jgg@ziepe.ca References: <20210118163006.61659-1-dgilbert@interlog.com> <20210118163006.61659-4-dgilbert@interlog.com> <20210119002741.4dbc290e@suse.de> From: Douglas Gilbert Message-ID: Date: Mon, 18 Jan 2021 20:04:20 -0500 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: <20210119002741.4dbc290e@suse.de> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-CA Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org On 2021-01-18 6:27 p.m., David Disseldorp wrote: > On Mon, 18 Jan 2021 11:30:05 -0500, Douglas Gilbert wrote: > >> After enabling copies between scatter gather lists (sgl_s), another >> storage related operation is to compare two sgl_s. This new function >> is modelled on NVMe's Compare command and the SCSI VERIFY(BYTCHK=1) >> command. Like memcmp() this function returns false on the first >> miscompare and stops comparing. >> >> A helper function called sgl_compare_sgl_idx() is added. It takes an >> additional parameter (miscompare_idx) which is a pointer. If that >> pointer is non-NULL and a miscompare is detected (i.e. the function >> returns false) then the byte index of the first miscompare is written >> to *miscomapre_idx. Knowing the location of the first miscompare is >> needed to implement the SCSI COMPARE AND WRITE command properly. >> >> Reviewed-by: Bodo Stroesser >> Signed-off-by: Douglas Gilbert >> --- >> include/linux/scatterlist.h | 8 +++ >> lib/scatterlist.c | 109 ++++++++++++++++++++++++++++++++++++ >> 2 files changed, 117 insertions(+) >> >> diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h >> index 3f836a3246aa..71be65f9ebb5 100644 >> --- a/include/linux/scatterlist.h >> +++ b/include/linux/scatterlist.h >> @@ -325,6 +325,14 @@ size_t sgl_copy_sgl(struct scatterlist *d_sgl, unsigned int d_nents, off_t d_ski >> struct scatterlist *s_sgl, unsigned int s_nents, off_t s_skip, >> size_t n_bytes); >> >> +bool sgl_compare_sgl(struct scatterlist *x_sgl, unsigned int x_nents, off_t x_skip, >> + struct scatterlist *y_sgl, unsigned int y_nents, off_t y_skip, >> + size_t n_bytes); >> + >> +bool sgl_compare_sgl_idx(struct scatterlist *x_sgl, unsigned int x_nents, off_t x_skip, >> + struct scatterlist *y_sgl, unsigned int y_nents, off_t y_skip, >> + size_t n_bytes, size_t *miscompare_idx); > > > This patch looks good and works fine as a replacement for > compare_and_write_do_cmp(). One minor suggestion would be to name it > sgl_equal() or similar, to perhaps better reflect the bool return and > avoid memcmp() confusion. Either way: > Reviewed-by: David Disseldorp Thanks. NVMe calls the command that does this Compare and SCSI uses COMPARE AND WRITE (and VERIFY(BYTCHK=1) ) but "equal" is fine with me. There will be another patchset version (at least) so there is time to change. Do you want: - sgl_equal(...), or - sgl_equal_sgl(...) ? Doug Gilbert