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=-9.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 042F9C34026 for ; Mon, 17 Feb 2020 18:50:01 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id AC35620725 for ; Mon, 17 Feb 2020 18:50:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="l7hv3PdT" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AC35620725 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linux-erofs-bounces+linux-erofs=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 48LtMV5BDjzDqjl for ; Tue, 18 Feb 2020 05:49:58 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=none (no SPF record) smtp.mailfrom=infradead.org (client-ip=2607:7c80:54:e::133; helo=bombadil.infradead.org; envelope-from=willy@infradead.org; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=infradead.org header.i=@infradead.org header.a=rsa-sha256 header.s=bombadil.20170209 header.b=l7hv3PdT; dkim-atps=neutral Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 48LtHN3r1tzDqX7 for ; Tue, 18 Feb 2020 05:46:24 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender :Reply-To:Content-Type:Content-ID:Content-Description; bh=f6e1vXABPDL0rMBXcPDUicTcSHShodWe/Rf26ms+MIM=; b=l7hv3PdTD5FlyDvtWj7UIPyYIh pFC/dM1GbjDjHpQBTch+Ju7Tj6oFrw59IcILNGPJj2pRhPguzUqywp4ihcqCujOiORMcLauMi6++M kn6iUgpEid7/AdCzyF06VM+n6zhEa4s9iKGvJ120z70Va5ZAEKt7ybAjLiNO1ZRtcnYM7cRhfYHny FViLwoiNRNq0gdWXh6D6fvopIONeuQBtk3up9M2TW0Ly/0YrIA1GEBuqfD5GflLHZuRNw8q2V6UNg AioV/Bgo3ETArbEHNGlWf/KkKm7VWOmabymzPwLel4x8sURqCjyXn6tWcxXkHiaNRugSbhMboBXBa CMyA7Qyw==; Received: from willy by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1j3lPL-00058v-ER; Mon, 17 Feb 2020 18:46:15 +0000 From: Matthew Wilcox To: linux-fsdevel@vger.kernel.org Subject: [PATCH v6 04/16] mm: Tweak readahead loop slightly Date: Mon, 17 Feb 2020 10:45:46 -0800 Message-Id: <20200217184613.19668-6-willy@infradead.org> X-Mailer: git-send-email 2.21.1 In-Reply-To: <20200217184613.19668-1-willy@infradead.org> References: <20200217184613.19668-1-willy@infradead.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: linux-erofs@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Development of Linux EROFS file system List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-xfs@vger.kernel.org, linux-kernel@vger.kernel.org, "Matthew Wilcox \(Oracle\)" , linux-f2fs-devel@lists.sourceforge.net, cluster-devel@redhat.com, linux-mm@kvack.org, ocfs2-devel@oss.oracle.com, linux-ext4@vger.kernel.org, linux-erofs@lists.ozlabs.org, linux-btrfs@vger.kernel.org Errors-To: linux-erofs-bounces+linux-erofs=archiver.kernel.org@lists.ozlabs.org Sender: "Linux-erofs" From: "Matthew Wilcox (Oracle)" Eliminate the page_offset variable which was just confusing; record the start of each consecutive run of pages in the readahead_control, and move the 'kick off a fresh batch' code to the end of the function for easier use in the next patch. Signed-off-by: Matthew Wilcox (Oracle) --- mm/readahead.c | 31 +++++++++++++++++++------------ 1 file changed, 19 insertions(+), 12 deletions(-) diff --git a/mm/readahead.c b/mm/readahead.c index 15329309231f..74791b96013f 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -154,7 +154,6 @@ void __do_page_cache_readahead(struct address_space *mapping, unsigned long lookahead_size) { struct inode *inode = mapping->host; - struct page *page; unsigned long end_index; /* The last page we want to read */ LIST_HEAD(page_pool); int page_idx; @@ -163,6 +162,7 @@ void __do_page_cache_readahead(struct address_space *mapping, struct readahead_control rac = { .mapping = mapping, .file = filp, + ._start = offset, ._nr_pages = 0, }; @@ -175,32 +175,39 @@ void __do_page_cache_readahead(struct address_space *mapping, * Preallocate as many pages as we will need. */ for (page_idx = 0; page_idx < nr_to_read; page_idx++) { - pgoff_t page_offset = offset + page_idx; + struct page *page; - if (page_offset > end_index) + if (offset > end_index) break; - page = xa_load(&mapping->i_pages, page_offset); + page = xa_load(&mapping->i_pages, offset); if (page && !xa_is_value(page)) { /* - * Page already present? Kick off the current batch of - * contiguous pages before continuing with the next - * batch. + * Page already present? Kick off the current batch + * of contiguous pages before continuing with the + * next batch. This page may be the one we would + * have intended to mark as Readahead, but we don't + * have a stable reference to this page, and it's + * not worth getting one just for that. */ - if (readahead_count(&rac)) - read_pages(&rac, &page_pool, gfp_mask); - rac._nr_pages = 0; - continue; + goto read; } page = __page_cache_alloc(gfp_mask); if (!page) break; - page->index = page_offset; + page->index = offset; list_add(&page->lru, &page_pool); if (page_idx == nr_to_read - lookahead_size) SetPageReadahead(page); rac._nr_pages++; + offset++; + continue; +read: + if (readahead_count(&rac)) + read_pages(&rac, &page_pool, gfp_mask); + rac._nr_pages = 0; + rac._start = ++offset; } /* -- 2.25.0