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 B64E6C433EF for ; Mon, 16 May 2022 12:36:27 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id E2D656B0071; Mon, 16 May 2022 08:36:26 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id DDC756B0072; Mon, 16 May 2022 08:36:26 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CA45B6B0073; Mon, 16 May 2022 08:36:26 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id B84B56B0071 for ; Mon, 16 May 2022 08:36:26 -0400 (EDT) Received: from smtpin28.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 84F6232C30 for ; Mon, 16 May 2022 12:36:26 +0000 (UTC) X-FDA: 79471554372.28.84660EE Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf05.hostedemail.com (Postfix) with ESMTP id 3D63E1000D5 for ; Mon, 16 May 2022 12:36:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=KMBErDmdZZ2SAaqJemuWdeIzHvPIQPmxERMuOxfXp2k=; b=W4vcg992u6Iv9bbE7yBTHa2lS9 IextbX8YLlAUPwOaJyXj3ibaTNrIIcvq9DS3oGXOaOHMCQeZIjIcnXnIsJMuj+3yirsX79t703CzP l/o+f40ErPO6RTz/BXJvGVd4HsXm/EI6eB1WXBU4YvuZ4ofc0PBV9/PQg/2TLJg2TAT1yJC1fiErs iBlyJsoQCPo2BWUlbQUQl31CowKmj63efcvPB/6CgZ5mUclMk/IvPRW/r/ftuFIFoMuubw5gU1T3j jGqEUu+lIwKj+Fa3JHmBMzuCIZaNxayJjpkU3sYanUTb1Oa7AICfutpeRjCrxurK1Fae7gsQ3lZ6s 5RgkVNyw==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1nqZxK-009sSS-4F; Mon, 16 May 2022 12:36:10 +0000 Date: Mon, 16 May 2022 13:36:10 +0100 From: Matthew Wilcox To: Hsin-Yi Wang Cc: Phillip Lougher , Xiongwei Song , Zheng Liang , Zhang Yi , Hou Tao , Miao Xie , Andrew Morton , "linux-mm @ kvack . org" , "squashfs-devel @ lists . sourceforge . net" , linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] squashfs: implement readahead Message-ID: References: <20220516105100.1412740-1-hsinyi@chromium.org> <20220516105100.1412740-3-hsinyi@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: q1i5k7fzjmqonmmrx9phqgjohbm98bp9 Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=W4vcg992; spf=none (imf05.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 3D63E1000D5 X-HE-Tag: 1652704563-532559 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: On Mon, May 16, 2022 at 07:04:08PM +0800, Hsin-Yi Wang wrote: > > + loff_t req_end = readahead_pos(ractl) + readahead_length(ractl); > > + loff_t start = readahead_pos(ractl) &~ mask; > > + size_t len = readahead_length(ractl) + readahead_pos(ractl) - start; > > + struct squashfs_page_actor *actor; > > + unsigned int nr_pages = 0; > > + struct page **pages; > > + u64 block = 0; > > + int bsize, res, i, index; > > + int file_end = i_size_read(inode) >> msblk->block_log; > > + unsigned int max_pages = 1UL << shift; > > + > > + readahead_expand(ractl, start, (len | mask) + 1); > > + > > + if (readahead_pos(ractl) + readahead_length(ractl) < req_end || > > + file_end == 0) > > + return; What's the first half of this condition supposed to be checking for? It seems to be checking whether readahead_expand() shrunk the range covered by the ractl, but readahead_expand() never does that, so I'm confused why you're checking for it.