From patchwork Fri Jan 22 21:36:10 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ross Zwisler X-Patchwork-Id: 8093591 Return-Path: X-Original-To: patchwork-linux-fsdevel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id D19F79F440 for ; Fri, 22 Jan 2016 21:41:17 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 16BE9205B5 for ; Fri, 22 Jan 2016 21:41:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 341A3205B1 for ; Fri, 22 Jan 2016 21:41:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755000AbcAVVlA (ORCPT ); Fri, 22 Jan 2016 16:41:00 -0500 Received: from mga03.intel.com ([134.134.136.65]:47314 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754507AbcAVVgW (ORCPT ); Fri, 22 Jan 2016 16:36:22 -0500 Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga103.jf.intel.com with ESMTP; 22 Jan 2016 13:36:21 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.22,333,1449561600"; d="scan'208";a="732559474" Received: from rzwisler-desk1.amr.corp.intel.com (HELO tarkir.lm.intel.com) ([10.232.112.142]) by orsmga003.jf.intel.com with ESMTP; 22 Jan 2016 13:36:21 -0800 From: Ross Zwisler To: linux-kernel@vger.kernel.org Cc: Ross Zwisler , Alexander Viro , Andrew Morton , Dan Williams , Dave Chinner , Jan Kara , Matthew Wilcox , linux-fsdevel@vger.kernel.org, linux-nvdimm@lists.01.org Subject: [PATCH v3 2/5] dax: clear TOWRITE flag after flush is complete Date: Fri, 22 Jan 2016 14:36:10 -0700 Message-Id: <1453498573-6328-3-git-send-email-ross.zwisler@linux.intel.com> X-Mailer: git-send-email 2.5.0 In-Reply-To: <1453498573-6328-1-git-send-email-ross.zwisler@linux.intel.com> References: <1453498573-6328-1-git-send-email-ross.zwisler@linux.intel.com> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable 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 Previously in dax_writeback_one() we cleared the PAGECACHE_TAG_TOWRITE flag before we had actually flushed the tagged radix tree entry to media. This is incorrect because of the following race: Thread 1 Thread 2 -------- -------- dax_writeback_mapping_range() tag entry with PAGECACHE_TAG_TOWRITE dax_writeback_mapping_range() tag entry with PAGECACHE_TAG_TOWRITE dax_writeback_one() radix_tree_tag_clear(TOWRITE) TOWRITE flag is no longer set, find_get_entries_tag() finds no entries, return flush entry to media In this case thread 1 returns before the data for the dirty entry is actually durable on media. Fix this by only clearing the PAGECACHE_TAG_TOWRITE flag after all flushing is complete. Signed-off-by: Ross Zwisler Reported-by: Jan Kara Reviewed-by: Jan Kara --- fs/dax.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/fs/dax.c b/fs/dax.c index cee9e1b..d589113 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -407,8 +407,6 @@ static int dax_writeback_one(struct block_device *bdev, if (!radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_TOWRITE)) goto unlock; - radix_tree_tag_clear(page_tree, index, PAGECACHE_TAG_TOWRITE); - if (WARN_ON_ONCE(type != RADIX_DAX_PTE && type != RADIX_DAX_PMD)) { ret = -EIO; goto unlock; @@ -432,6 +430,10 @@ static int dax_writeback_one(struct block_device *bdev, } wb_cache_pmem(dax.addr, dax.size); + + spin_lock_irq(&mapping->tree_lock); + radix_tree_tag_clear(page_tree, index, PAGECACHE_TAG_TOWRITE); + spin_unlock_irq(&mapping->tree_lock); unmap: dax_unmap_atomic(bdev, &dax); return ret;