From patchwork Thu Mar 10 19:18:50 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jan Kara X-Patchwork-Id: 8559611 Return-Path: X-Original-To: patchwork-linux-nvdimm@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 337179F2B4 for ; Thu, 10 Mar 2016 19:18:45 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 08C8520384 for ; Thu, 10 Mar 2016 19:18:44 +0000 (UTC) Received: from ml01.01.org (ml01.01.org [198.145.21.10]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 17CF62037C for ; Thu, 10 Mar 2016 19:18:43 +0000 (UTC) Received: from [127.0.0.1] (localhost [IPv6:::1]) by ml01.01.org (Postfix) with ESMTP id 8C7511A1F6A; Thu, 10 Mar 2016 11:18:57 -0800 (PST) X-Original-To: linux-nvdimm@lists.01.org Delivered-To: linux-nvdimm@lists.01.org Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 431DD1A1F5B for ; Thu, 10 Mar 2016 11:18:54 -0800 (PST) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 5114EACC6; Thu, 10 Mar 2016 19:18:36 +0000 (UTC) Received: by quack.suse.cz (Postfix, from userid 1000) id 372B482525; Thu, 10 Mar 2016 20:18:57 +0100 (CET) From: Jan Kara To: linux-fsdevel@vger.kernel.org Subject: [PATCH 07/12] dax: Fix data corruption for written and mmapped files Date: Thu, 10 Mar 2016 20:18:50 +0100 Message-Id: <1457637535-21633-8-git-send-email-jack@suse.cz> X-Mailer: git-send-email 2.6.2 In-Reply-To: <1457637535-21633-1-git-send-email-jack@suse.cz> References: <1457637535-21633-1-git-send-email-jack@suse.cz> Cc: Jan Kara , linux-nvdimm@lists.01.org, NeilBrown , "Wilcox, Matthew R" X-BeenThere: linux-nvdimm@lists.01.org X-Mailman-Version: 2.1.17 Precedence: list List-Id: "Linux-nvdimm developer list." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_NONE, 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 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 f53b13d9644b..4aa440f9305b 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -580,11 +580,6 @@ 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, @@ -661,7 +656,7 @@ 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); @@ -933,8 +928,6 @@ 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;