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=-6.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT 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 AD5E8C43457 for ; Mon, 19 Oct 2020 19:19:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5DE1922283 for ; Mon, 19 Oct 2020 19:19:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731123AbgJSTTf (ORCPT ); Mon, 19 Oct 2020 15:19:35 -0400 Received: from smtp.infotech.no ([82.134.31.41]:56022 "EHLO smtp.infotech.no" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730938AbgJSTTf (ORCPT ); Mon, 19 Oct 2020 15:19:35 -0400 Received: from localhost (localhost [127.0.0.1]) by smtp.infotech.no (Postfix) with ESMTP id 5ABDC204248; Mon, 19 Oct 2020 21:19:32 +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 M1MqUhragf6R; Mon, 19 Oct 2020 21:19:32 +0200 (CEST) Received: from xtwo70.bingwo.ca (vpn.infotech.no [82.134.31.155]) by smtp.infotech.no (Postfix) with ESMTPA id 0AF2520414F; Mon, 19 Oct 2020 21:19:30 +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 v3 0/4] scatterlist: add new capabilities Date: Mon, 19 Oct 2020 15:19:24 -0400 Message-Id: <20201019191928.77845-1-dgilbert@interlog.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Scatter-gather lists (sgl_s) are frequently used as data carriers in the block layer. For example the SCSI and NVMe subsystems interchange data with the block layer using sgl_s. The sgl API is declared in The author has extended these transient sgl use cases to a store (i.e. a ramdisk) in the scsi_debug driver. Other new potential uses of sgl_s could be for caches. When this extra step is taken, the need to copy between sgl_s becomes apparent. The patchset adds sgl_copy_sgl() and two other sgl operations. The existing sgl_alloc_order() function can be seen as a replacement for vmalloc() for large, long-term allocations. For what seems like no good reason, sgl_alloc_order() currently restricts its total allocation to less than or equal to 4 GiB. vmalloc() has no such restriction. Changes since v2 [posted 20201018]: - remove unneeded lines from sgl_memset() definition. - change sg_zero_buffer() to call sgl_memset() as the former is a subset. Changes since v1 [posted 20201016]: - Bodo Stroesser pointed out a problem with the nesting of kmap_atomic() [called via sg_miter_next()] and kunmap_atomic() calls [called via sg_miter_stop()] and proposed a solution that simplifies the previous code. - the new implementation of the three functions has shorter periods when pre-emption is disabled (but has more them). This should make operations on large sgl_s more pre-emption "friendly" with a relatively small performance hit. - sgl_memset return type changed from void to size_t and is the number of bytes actually (over)written. That number is needed anyway internally so may as well return it as it may be useful to the caller. This patchset is against lk 5.9.0 Douglas Gilbert (4): sgl_alloc_order: remove 4 GiB limit, sgl_free() warning scatterlist: add sgl_copy_sgl() function scatterlist: add sgl_compare_sgl() function scatterlist: add sgl_memset() include/linux/scatterlist.h | 12 +++ lib/scatterlist.c | 186 +++++++++++++++++++++++++++++++++--- 2 files changed, 184 insertions(+), 14 deletions(-) -- 2.25.1