From patchwork Tue Feb 22 03:17:17 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: NeilBrown X-Patchwork-Id: 12754443 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5CBABC433FE for ; Tue, 22 Feb 2022 03:18:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240000AbiBVDTB (ORCPT ); Mon, 21 Feb 2022 22:19:01 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:43042 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233775AbiBVDTA (ORCPT ); Mon, 21 Feb 2022 22:19:00 -0500 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CE17BFFB; Mon, 21 Feb 2022 19:18:34 -0800 (PST) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 3ABF61F392; Tue, 22 Feb 2022 03:18:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1645499913; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=dxMNB30lzl6BwAspjhyrqZOLtIFrR9DXCk9OQJHPtUY=; b=W7ebGdMAlezFqBmfhUhJtFLKOkWJeos9pQHX2grBMDLkQg4vopHgKFVTPQqtciX/3uFXle LS7sGhVKANsry9bX1t+C90K8NvDOgUWBOJdfcsjev7nJWmTO6WYZvG1tAfszx73V8g317v IPQ6JQNv6q0a7ebKuPJwoY3rm6bp6Jg= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1645499913; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=dxMNB30lzl6BwAspjhyrqZOLtIFrR9DXCk9OQJHPtUY=; b=G7n/l/aOQFd/9dtTrzc2aloiCvbC6lUJXd2tD1UOdI3tXRXAymBbJgRLyF1oHS6++KH8Ts e4yVYzL7OFocyEBw== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 92B2413BA7; Tue, 22 Feb 2022 03:18:23 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id 5RPZKv9VFGKFWgAAMHmgww (envelope-from ); Tue, 22 Feb 2022 03:18:23 +0000 Subject: [PATCH 03/11] MM: improve cleanup when ->readpages doesn't process all pages. From: NeilBrown To: Andrew Morton , Jan Kara , Wu Fengguang , Jaegeuk Kim , Chao Yu , Jeff Layton , Ilya Dryomov , Miklos Szeredi , Trond Myklebust , Anna Schumaker , Ryusuke Konishi , "Darrick J. Wong" , Philipp Reisner , Lars Ellenberg , Paolo Valente , Jens Axboe Cc: linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-nilfs@vger.kernel.org, linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-ext4@vger.kernel.org, ceph-devel@vger.kernel.org, drbd-dev@lists.linbit.com, linux-kernel@vger.kernel.org Date: Tue, 22 Feb 2022 14:17:17 +1100 Message-ID: <164549983736.9187.16755913785880819183.stgit@noble.brown> In-Reply-To: <164549971112.9187.16871723439770288255.stgit@noble.brown> References: <164549971112.9187.16871723439770288255.stgit@noble.brown> User-Agent: StGit/0.23 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org If ->readpages doesn't process all the pages, then it is best to act as though they weren't requested so that a subsequent readahead can try again. So: - remove any 'ahead' pages from the page cache so they can be loaded with ->readahead() rather then multiple ->read()s - update the file_ra_state to reflect the reads that were actually submitted. This allows ->readpages() to abort early due e.g. to congestion, which will then allow us to remove the inode_read_congested() test from page_Cache_async_ra(). Signed-off-by: NeilBrown --- mm/readahead.c | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-) diff --git a/mm/readahead.c b/mm/readahead.c index 73b2bc5302e0..8a97bd408cf6 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -104,7 +104,13 @@ * for necessary resources (e.g. memory or indexing information) to * become available. Pages in the final ``async_size`` may be * considered less urgent and failure to read them is more acceptable. - * They will eventually be read individually using ->readpage(). + * In this case it is best to use delete_from_page_cache() to remove the + * pages from the page cache as is automatically done for pages that + * were not fetched with readahead_page(). This will allow a + * subsequent synchronous read ahead request to try them again. If they + * are left in the page cache, then they will be read individually using + * ->readpage(). + * */ #include @@ -226,8 +232,17 @@ static void read_pages(struct readahead_control *rac, struct list_head *pages, if (aops->readahead) { aops->readahead(rac); - /* Clean up the remaining pages */ + /* + * Clean up the remaining pages. The sizes in ->ra + * maybe be used to size next read-ahead, so make sure + * they accurately reflect what happened. + */ while ((page = readahead_page(rac))) { + rac->ra->size -= 1; + if (rac->ra->async_size > 0) { + rac->ra->async_size -= 1; + delete_from_page_cache(page); + } unlock_page(page); put_page(page); }