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=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 56880C433E9 for ; Mon, 18 Jan 2021 23:28:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2EE4122EBF for ; Mon, 18 Jan 2021 23:28:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732916AbhARX21 (ORCPT ); Mon, 18 Jan 2021 18:28:27 -0500 Received: from mx2.suse.de ([195.135.220.15]:40932 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730086AbhARX2Z (ORCPT ); Mon, 18 Jan 2021 18:28:25 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 7483EAB9F; Mon, 18 Jan 2021 23:27:43 +0000 (UTC) Date: Tue, 19 Jan 2021 00:27:41 +0100 From: David Disseldorp To: Douglas Gilbert 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 Subject: Re: [PATCH v6 3/4] scatterlist: add sgl_compare_sgl() function Message-ID: <20210119002741.4dbc290e@suse.de> In-Reply-To: <20210118163006.61659-4-dgilbert@interlog.com> References: <20210118163006.61659-1-dgilbert@interlog.com> <20210118163006.61659-4-dgilbert@interlog.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org 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 Cheers, David