From patchwork Sun Oct 18 17:13:36 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Douglas Gilbert X-Patchwork-Id: 11843337 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=-12.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 68874C433E7 for ; Sun, 18 Oct 2020 17:14:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3B18E2063A for ; Sun, 18 Oct 2020 17:14:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727398AbgJRRNy (ORCPT ); Sun, 18 Oct 2020 13:13:54 -0400 Received: from smtp.infotech.no ([82.134.31.41]:52056 "EHLO smtp.infotech.no" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727377AbgJRRNy (ORCPT ); Sun, 18 Oct 2020 13:13:54 -0400 Received: from localhost (localhost [127.0.0.1]) by smtp.infotech.no (Postfix) with ESMTP id E3C01204255; Sun, 18 Oct 2020 19:13:51 +0200 (CEST) X-Virus-Scanned: by amavisd-new-2.6.6 (20110518) (Debian) at infotech.no Received: from smtp.infotech.no ([127.0.0.1]) by localhost (smtp.infotech.no [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id gHPwiAFxcovT; Sun, 18 Oct 2020 19:13:49 +0200 (CEST) Received: from xtwo70.bingwo.ca (host-104-157-204-209.dyn.295.ca [104.157.204.209]) by smtp.infotech.no (Postfix) with ESMTPA id 1DDB720418E; Sun, 18 Oct 2020 19:13:47 +0200 (CEST) From: Douglas Gilbert To: linux-scsi@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Cc: martin.petersen@oracle.com, axboe@kernel.dk, bvanassche@acm.org, bostroesser@gmail.com Subject: [PATCH v2 4/4] scatterlist: add sgl_memset() Date: Sun, 18 Oct 2020 13:13:36 -0400 Message-Id: <20201018171336.63839-5-dgilbert@interlog.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20201018171336.63839-1-dgilbert@interlog.com> References: <20201018171336.63839-1-dgilbert@interlog.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org The existing sg_zero_buffer() function is a bit restrictive. For example protection information (PI) blocks are usually initialized to 0xff bytes. As its name suggests sgl_memset() is modelled on memset(). One difference is the type of the val argument which is u8 rather than int. Plus it returns the number of bytes (over)written. Signed-off-by: Douglas Gilbert --- include/linux/scatterlist.h | 3 +++ lib/scatterlist.c | 54 ++++++++++++++++++++++++++++++++++--- 2 files changed, 54 insertions(+), 3 deletions(-) diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h index ae260dc5fedb..a40012c8a4e6 100644 --- a/include/linux/scatterlist.h +++ b/include/linux/scatterlist.h @@ -329,6 +329,9 @@ bool sgl_compare_sgl(struct scatterlist *x_sgl, unsigned int x_nents, off_t x_sk struct scatterlist *y_sgl, unsigned int y_nents, off_t y_skip, size_t n_bytes); +size_t sgl_memset(struct scatterlist *sgl, unsigned int nents, off_t skip, + u8 val, size_t n_bytes); + /* * Maximum number of entries that will be allocated in one piece, if * a list larger than this is required then chaining will be utilized. diff --git a/lib/scatterlist.c b/lib/scatterlist.c index d910776a4c96..a704039ab54d 100644 --- a/lib/scatterlist.c +++ b/lib/scatterlist.c @@ -985,7 +985,8 @@ EXPORT_SYMBOL(sg_zero_buffer); * @s_skip: Number of bytes to skip in source before starting * @n_bytes: The (maximum) number of bytes to copy * - * Returns the number of copied bytes. + * Returns: + * The number of copied bytes. * * Notes: * Destination arguments appear before the source arguments, as with memcpy(). @@ -1058,8 +1059,9 @@ EXPORT_SYMBOL(sgl_copy_sgl); * @y_skip: Number of bytes to skip in y (right) before starting * @n_bytes: The (maximum) number of bytes to compare * - * Returns true if x and y compare equal before x, y or n_bytes is exhausted. - * Otherwise on a miscompare, returns false (and stops comparing). + * Returns: + * true if x and y compare equal before x, y or n_bytes is exhausted. + * Otherwise on a miscompare, returns false (and stops comparing). * * Notes: * x and y are symmetrical: they can be swapped and the result is the same. @@ -1108,3 +1110,49 @@ bool sgl_compare_sgl(struct scatterlist *x_sgl, unsigned int x_nents, off_t x_sk return equ; } EXPORT_SYMBOL(sgl_compare_sgl); + +/** + * sgl_memset - set byte 'val' up to n_bytes times on SG list + * @sgl: The SG list + * @nents: Number of SG entries in sgl + * @skip: Number of bytes to skip before starting + * @val: byte value to write to sgl + * @n_bytes: The (maximum) number of bytes to modify + * + * Returns: + * The number of bytes written. + * + * Notes: + * Stops writing if either sgl or n_bytes is exhausted. If n_bytes is + * set SIZE_MAX then val will be written to each byte until the end + * of sgl. + * + * The notes in sgl_copy_sgl() about large sgl_s _applies here as well. + * + **/ +size_t sgl_memset(struct scatterlist *sgl, unsigned int nents, off_t skip, + u8 val, size_t n_bytes) +{ + size_t offset = 0; + size_t len; + struct sg_mapping_iter miter; + + if (n_bytes == 0) + return 0; + sg_miter_start(&miter, sgl, nents, SG_MITER_ATOMIC | SG_MITER_TO_SG); + if (!sg_miter_skip(&miter, skip)) + goto fini; + + while ((offset < n_bytes) && sg_miter_next(&miter)) { + len = min(miter.length, n_bytes - offset); + memset(miter.addr, val, len); + offset += len; + miter.consumed = len; + sg_miter_stop(&miter); + } +fini: + sg_miter_stop(&miter); + return offset; +} +EXPORT_SYMBOL(sgl_memset); +