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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 20BD0C4332F for ; Mon, 9 May 2022 13:14:28 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 471A66B0088; Mon, 9 May 2022 09:14:19 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 3FBA76B0089; Mon, 9 May 2022 09:14:19 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 226886B008A; Mon, 9 May 2022 09:14:19 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 036106B0088 for ; Mon, 9 May 2022 09:14:19 -0400 (EDT) Received: from smtpin23.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id C9425210D9 for ; Mon, 9 May 2022 13:14:18 +0000 (UTC) X-FDA: 79446248196.23.7205113 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by imf15.hostedemail.com (Postfix) with ESMTP id 0CDF1A008A for ; Mon, 9 May 2022 13:14:05 +0000 (UTC) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.55]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4KxhSp0hK8zhZ3Q; Mon, 9 May 2022 21:13:46 +0800 (CST) Received: from huawei.com (10.175.124.27) by canpemm500002.china.huawei.com (7.192.104.244) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Mon, 9 May 2022 21:14:09 +0800 From: Miaohe Lin To: CC: , , , , , , , , , , , Subject: [PATCH 15/15] mm/swap: fix comment about swap extent Date: Mon, 9 May 2022 21:14:16 +0800 Message-ID: <20220509131416.17553-16-linmiaohe@huawei.com> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20220509131416.17553-1-linmiaohe@huawei.com> References: <20220509131416.17553-1-linmiaohe@huawei.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-Originating-IP: [10.175.124.27] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To canpemm500002.china.huawei.com (7.192.104.244) X-CFilter-Loop: Reflected X-Rspamd-Queue-Id: 0CDF1A008A X-Stat-Signature: jg6xs7ezdjt4ps7sk9neyrjzzpqnt9xz Authentication-Results: imf15.hostedemail.com; dkim=none; dmarc=pass (policy=quarantine) header.from=huawei.com; spf=pass (imf15.hostedemail.com: domain of linmiaohe@huawei.com designates 45.249.212.187 as permitted sender) smtp.mailfrom=linmiaohe@huawei.com X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1652102045-435107 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Since commit 4efaceb1c5f8 ("mm, swap: use rbtree for swap_extent"), rbtree is used for swap extent. Also curr_swap_extent is removed at that time. Update the corresponding comment. Signed-off-by: Miaohe Lin --- include/linux/swap.h | 4 ++-- mm/swapfile.c | 15 ++++++--------- 2 files changed, 8 insertions(+), 11 deletions(-) diff --git a/include/linux/swap.h b/include/linux/swap.h index 8772132d21dc..e1f3201dec6f 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -173,8 +173,8 @@ struct zone; /* * A swap extent maps a range of a swapfile's PAGE_SIZE pages onto a range of - * disk blocks. A list of swap extents maps the entire swapfile. (Where the - * term `swapfile' refers to either a blockdevice or an IS_REG file. Apart + * disk blocks. A rbtree of swap extents maps the entire swapfile (Where the + * term `swapfile' refers to either a blockdevice or an IS_REG file). Apart * from setup, they're handled identically. * * We always assume that blocks are of size PAGE_SIZE. diff --git a/mm/swapfile.c b/mm/swapfile.c index 7ead5fb96d9d..b3f977d9c83e 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -2225,8 +2225,8 @@ EXPORT_SYMBOL_GPL(add_swap_extent); /* * A `swap extent' is a simple thing which maps a contiguous range of pages - * onto a contiguous range of disk blocks. An ordered list of swap extents - * is built at swapon time and is then used at swap_writepage/swap_readpage + * onto a contiguous range of disk blocks. A rbtree of swap extents is + * built at swapon time and is then used at swap_writepage/swap_readpage * time for locating where on disk a page belongs. * * If the swapfile is an S_ISBLK block device, a single extent is installed. @@ -2234,12 +2234,12 @@ EXPORT_SYMBOL_GPL(add_swap_extent); * swap files identically. * * Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap - * extent list operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK + * extent rbtree operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK * swapfiles are handled *identically* after swapon time. * * For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks - * and will parse them into an ordered extent list, in PAGE_SIZE chunks. If - * some stray blocks are found which do not fall within the PAGE_SIZE alignment + * and will parse them into a rbtree, in PAGE_SIZE chunks. If some stray + * blocks are found which do not fall within the PAGE_SIZE alignment * requirements, they are simply tossed out - we will never use those blocks * for swapping. * @@ -2248,10 +2248,7 @@ EXPORT_SYMBOL_GPL(add_swap_extent); * * The amount of disk space which a single swap extent represents varies. * Typically it is in the 1-4 megabyte range. So we can have hundreds of - * extents in the list. To avoid much list walking, we cache the previous - * search location in `curr_swap_extent', and start new searches from there. - * This is extremely effective. The average number of iterations in - * map_swap_page() has been measured at about 0.3 per page. - akpm. + * extents in the rbtree. - akpm. */ static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span) { -- 2.23.0