From patchwork Mon Mar 21 13:22:49 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jan Kara X-Patchwork-Id: 8632811 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 6A9469F372 for ; Mon, 21 Mar 2016 13:22:39 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id BA8D8201DD for ; Mon, 21 Mar 2016 13:22:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B27E620306 for ; Mon, 21 Mar 2016 13:22:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755463AbcCUNWf (ORCPT ); Mon, 21 Mar 2016 09:22:35 -0400 Received: from mx2.suse.de ([195.135.220.15]:51678 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754886AbcCUNWb (ORCPT ); Mon, 21 Mar 2016 09:22:31 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 93C83ACB4; Mon, 21 Mar 2016 13:22:29 +0000 (UTC) Received: by quack.suse.cz (Postfix, from userid 1000) id B557882522; Mon, 21 Mar 2016 14:22:58 +0100 (CET) From: Jan Kara To: linux-fsdevel@vger.kernel.org Cc: "Wilcox, Matthew R" , Ross Zwisler , Dan Williams , linux-nvdimm@lists.01.org, NeilBrown , Jan Kara Subject: [PATCH 04/10] dax: Fix data corruption for written and mmapped files Date: Mon, 21 Mar 2016 14:22:49 +0100 Message-Id: <1458566575-28063-5-git-send-email-jack@suse.cz> X-Mailer: git-send-email 2.6.2 In-Reply-To: <1458566575-28063-1-git-send-email-jack@suse.cz> References: <1458566575-28063-1-git-send-email-jack@suse.cz> 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=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 When a fault to a hole races with write filling the hole, it can happen that block zeroing in __dax_fault() overwrites the data copied by write. Since filesystem is supposed to provide pre-zeroed blocks for fault anyway, just remove the racy zeroing from dax code. The only catch is with read-faults over unwritten block where __dax_fault() filled in the block into page tables anyway. For that case we have to fall back to using hole page now. Signed-off-by: Jan Kara --- fs/dax.c | 9 +-------- 1 file changed, 1 insertion(+), 8 deletions(-) diff --git a/fs/dax.c b/fs/dax.c index d496466652cd..50d81172438b 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -582,11 +582,6 @@ static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh, error = PTR_ERR(dax.addr); goto out; } - - if (buffer_unwritten(bh) || buffer_new(bh)) { - clear_pmem(dax.addr, PAGE_SIZE); - wmb_pmem(); - } dax_unmap_atomic(bdev, &dax); error = dax_radix_entry(mapping, vmf->pgoff, dax.sector, false, @@ -665,7 +660,7 @@ int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, if (error) goto unlock_page; - if (!buffer_mapped(&bh) && !buffer_unwritten(&bh) && !vmf->cow_page) { + if (!buffer_mapped(&bh) && !vmf->cow_page) { if (vmf->flags & FAULT_FLAG_WRITE) { error = get_block(inode, block, &bh, 1); count_vm_event(PGMAJFAULT); @@ -950,8 +945,6 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, } if (buffer_unwritten(&bh) || buffer_new(&bh)) { - clear_pmem(dax.addr, PMD_SIZE); - wmb_pmem(); count_vm_event(PGMAJFAULT); mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT); result |= VM_FAULT_MAJOR;