From patchwork Tue Nov 28 18:40:36 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mike Christie X-Patchwork-Id: 10080883 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id A065F602BC for ; Tue, 28 Nov 2017 18:40:59 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 984662958B for ; Tue, 28 Nov 2017 18:40:59 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 8D0802958F; Tue, 28 Nov 2017 18:40:59 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id AE8952958B for ; Tue, 28 Nov 2017 18:40:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754052AbdK1Sk4 (ORCPT ); Tue, 28 Nov 2017 13:40:56 -0500 Received: from mx1.redhat.com ([209.132.183.28]:38392 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754038AbdK1Skz (ORCPT ); Tue, 28 Nov 2017 13:40:55 -0500 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 8E36B883BA; Tue, 28 Nov 2017 18:40:55 +0000 (UTC) Received: from rh2.redhat.com (ovpn-125-222.rdu2.redhat.com [10.10.125.222]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9A763600D1; Tue, 28 Nov 2017 18:40:54 +0000 (UTC) From: Mike Christie To: target-devel@vger.kernel.org, nab@linux-iscsi.org Cc: Xiubo Li , Mike Christie Subject: [PATCH 10/15] tcmu: clean up the scatter helper Date: Tue, 28 Nov 2017 12:40:36 -0600 Message-Id: <1511894441-8626-11-git-send-email-mchristi@redhat.com> In-Reply-To: <1511894441-8626-1-git-send-email-mchristi@redhat.com> References: <1511894441-8626-1-git-send-email-mchristi@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Tue, 28 Nov 2017 18:40:55 +0000 (UTC) Sender: target-devel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: target-devel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Xiubo Li Add some comments to make the scatter code to be more readable, and drop unused arg to new_iov. Signed-off-by: Xiubo Li Signed-off-by: Mike Christie --- drivers/target/target_core_user.c | 30 +++++++++++++++++++++++++----- 1 file changed, 25 insertions(+), 5 deletions(-) diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c index 5d1daea..8d0dc47 100644 --- a/drivers/target/target_core_user.c +++ b/drivers/target/target_core_user.c @@ -492,8 +492,7 @@ static inline size_t head_to_end(size_t head, size_t size) return size - head; } -static inline void new_iov(struct iovec **iov, int *iov_cnt, - struct tcmu_dev *udev) +static inline void new_iov(struct iovec **iov, int *iov_cnt) { struct iovec *iovec; @@ -546,19 +545,38 @@ static void scatter_data_area(struct tcmu_dev *udev, to = kmap_atomic(page); } - copy_bytes = min_t(size_t, sg_remaining, - block_remaining); + /* + * Covert to virtual offset of the ring data area. + */ to_offset = get_block_offset_user(udev, dbi, block_remaining); + /* + * The following code will gather and map the blocks + * to the same iovec when the blocks are all next to + * each other. + */ + copy_bytes = min_t(size_t, sg_remaining, + block_remaining); if (*iov_cnt != 0 && to_offset == iov_tail(*iov)) { + /* + * Will append to the current iovec, because + * the current block page is next to the + * previous one. + */ (*iov)->iov_len += copy_bytes; } else { - new_iov(iov, iov_cnt, udev); + /* + * Will allocate a new iovec because we are + * first time here or the current block page + * is not next to the previous one. + */ + new_iov(iov, iov_cnt); (*iov)->iov_base = (void __user *)to_offset; (*iov)->iov_len = copy_bytes; } + if (copy_data) { offset = DATA_BLOCK_SIZE - block_remaining; memcpy(to + offset, @@ -566,11 +584,13 @@ static void scatter_data_area(struct tcmu_dev *udev, copy_bytes); tcmu_flush_dcache_range(to, copy_bytes); } + sg_remaining -= copy_bytes; block_remaining -= copy_bytes; } kunmap_atomic(from - sg->offset); } + if (to) kunmap_atomic(to); }