From patchwork Fri Jul 11 14:20:46 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Weston Andros Adamson X-Patchwork-Id: 4534921 Return-Path: X-Original-To: patchwork-linux-nfs@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id D26749F1C4 for ; Fri, 11 Jul 2014 14:20:59 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 0E1172017A for ; Fri, 11 Jul 2014 14:20:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3D39020166 for ; Fri, 11 Jul 2014 14:20:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754814AbaGKOUz (ORCPT ); Fri, 11 Jul 2014 10:20:55 -0400 Received: from mail-ig0-f176.google.com ([209.85.213.176]:46803 "EHLO mail-ig0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754744AbaGKOUy (ORCPT ); Fri, 11 Jul 2014 10:20:54 -0400 Received: by mail-ig0-f176.google.com with SMTP id r10so4306167igi.3 for ; Fri, 11 Jul 2014 07:20:54 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=otog4zLP+rzgcyM9a+RkZraMRYVyWNEAqUZwJo2SX8A=; b=fgD4oaSA42cyuDo60Ymj7r92cGz88An2zyRqUoezK3hKjbiKiyTkBSUbJooZh8id6m wdCgIvfQPyZSL/z+hE5q6NHyB3BaYOPQvwNPJdpRV2BN4rfehJgxRbUOmYvs5r3ijLvx rsjMadgD4mW+MBHUxesB2grCtTdP4K+jqm0nvx7L+wpk+daKnGejAM1a3uAyKV+skE5V hHcruTwexVBECbXhIOztIv+XQsuNP9vO7td5Fl/sbyAfrBfdAkDpQymI2tVrDl8LtTPm z4y5ZpPSWs3o7vj+dmDs0ewPlJI+3cdSfjGJHDGBgYq8B/JHbm1qlAFZHaoGIXAGEMw/ p7LQ== X-Gm-Message-State: ALoCoQlxXTi460iWqaE8MkP1PwY37b8/K/Mfe9lpt6NVLtMin/4P/HLO41gEKpm95Q4sP5kh0WDQ X-Received: by 10.43.137.74 with SMTP id in10mr5053959icc.54.1405088454055; Fri, 11 Jul 2014 07:20:54 -0700 (PDT) Received: from gavrio-wifi.robotsandstuff.fake (c-98-209-19-144.hsd1.mi.comcast.net. [98.209.19.144]) by mx.google.com with ESMTPSA id v6sm6334244igz.21.2014.07.11.07.20.53 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Fri, 11 Jul 2014 07:20:53 -0700 (PDT) From: Weston Andros Adamson To: trond.myklebust@primarydata.com Cc: linux-nfs@vger.kernel.org, Weston Andros Adamson Subject: [PATCH 2/5] nfs: nfs_page should take a ref on the head req Date: Fri, 11 Jul 2014 10:20:46 -0400 Message-Id: <1405088449-11268-3-git-send-email-dros@primarydata.com> X-Mailer: git-send-email 1.8.5.2 (Apple Git-48) In-Reply-To: <1405088449-11268-1-git-send-email-dros@primarydata.com> References: <1405088449-11268-1-git-send-email-dros@primarydata.com> Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org X-Spam-Status: No, score=-7.5 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP nfs_pages that aren't the the head of a group must take a reference on the head as long as ->wb_head is set to it. This stops the head from hitting a refcount of 0 while there is still an active nfs_page for the page group. This avoids kref warnings in the writeback code when the page group head is found and referenced. Signed-off-by: Weston Andros Adamson --- fs/nfs/pagelist.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c index 50e10bb..8b074da 100644 --- a/fs/nfs/pagelist.c +++ b/fs/nfs/pagelist.c @@ -239,15 +239,21 @@ nfs_page_group_init(struct nfs_page *req, struct nfs_page *prev) WARN_ON_ONCE(prev == req); if (!prev) { + /* a head request */ req->wb_head = req; req->wb_this_page = req; } else { + /* a subrequest */ WARN_ON_ONCE(prev->wb_this_page != prev->wb_head); WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &prev->wb_head->wb_flags)); req->wb_head = prev->wb_head; req->wb_this_page = prev->wb_this_page; prev->wb_this_page = req; + /* All subrequests take a ref on the head request until + * nfs_page_group_destroy is called */ + kref_get(&req->wb_head->wb_kref); + /* grab extra ref if head request has extra ref from * the write/commit path to handle handoff between write * and commit lists */ @@ -271,6 +277,10 @@ nfs_page_group_destroy(struct kref *kref) struct nfs_page *req = container_of(kref, struct nfs_page, wb_kref); struct nfs_page *tmp, *next; + /* subrequests must release the ref on the head request */ + if (req->wb_head != req) + nfs_release_request(req->wb_head); + if (!nfs_page_group_sync_on_bit(req, PG_TEARDOWN)) return;