From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DA356C433E0 for ; Tue, 23 Jun 2020 19:47:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B0D16207E8 for ; Tue, 23 Jun 2020 19:47:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="IvWF1W/s" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387420AbgFWTrv (ORCPT ); Tue, 23 Jun 2020 15:47:51 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:59544 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1733220AbgFWTrv (ORCPT ); Tue, 23 Jun 2020 15:47:51 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1592941669; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=5RCUhT3+bHdeyKEuG4wz3jVY4UlEWG0x4f4cHn8cig4=; b=IvWF1W/sOIEqekaxHGROlaAqtJWXtqsK5KRGLDwGsYo2qGvOlauHXGFGvZSrQB83w/2iSD TwH4hsqPoWQZvKIPQ+soOEZ08azKsyKtPVlujYQ4M6mjSV25l4ogLRf6vAvGopFhjhAfqa v/qYXNQxzZeLWsZZ4Nkb5W39PaOpMS8= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-18-8Ha2YXNkMV6GlG_erQi7mQ-1; Tue, 23 Jun 2020 15:47:47 -0400 X-MC-Unique: 8Ha2YXNkMV6GlG_erQi7mQ-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 5B54B8018A5; Tue, 23 Jun 2020 19:47:46 +0000 (UTC) Received: from bfoster (dhcp-41-2.bos.redhat.com [10.18.41.2]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 035775D9D3; Tue, 23 Jun 2020 19:47:45 +0000 (UTC) Date: Tue, 23 Jun 2020 15:47:44 -0400 From: Brian Foster To: Dave Chinner Cc: linux-xfs@vger.kernel.org Subject: Re: [PATCH] xfs: use MMAPLOCK around filemap_map_pages() Message-ID: <20200623194744.GC56510@bfoster> References: <20200623052059.1893966-1-david@fromorbit.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200623052059.1893966-1-david@fromorbit.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Tue, Jun 23, 2020 at 03:20:59PM +1000, Dave Chinner wrote: > From: Dave Chinner > > The page faultround path ->map_pages is implemented in XFS via > filemap_map_pages(). This function checks that pages found in page > cache lookups have not raced with truncate based invalidation by > checking page->mapping is correct and page->index is within EOF. > > However, we've known for a long time that this is not sufficient to > protect against races with invalidations done by operations that do > not change EOF. e.g. hole punching and other fallocate() based > direct extent manipulations. The way we protect against these > races is we wrap the page fault operations in a XFS_MMAPLOCK_SHARED > lock so they serialise against fallocate and truncate before calling > into the filemap function that processes the fault. > > Do the same for XFS's ->map_pages implementation to close this > potential data corruption issue. > > Signed-off-by: Dave Chinner > --- Looks reasonable: Reviewed-by: Brian Foster > fs/xfs/xfs_file.c | 15 ++++++++++++++- > 1 file changed, 14 insertions(+), 1 deletion(-) > > diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c > index 7b05f8fd7b3d..4b185a907432 100644 > --- a/fs/xfs/xfs_file.c > +++ b/fs/xfs/xfs_file.c > @@ -1266,10 +1266,23 @@ xfs_filemap_pfn_mkwrite( > return __xfs_filemap_fault(vmf, PE_SIZE_PTE, true); > } > > +static void > +xfs_filemap_map_pages( > + struct vm_fault *vmf, > + pgoff_t start_pgoff, > + pgoff_t end_pgoff) > +{ > + struct inode *inode = file_inode(vmf->vma->vm_file); > + > + xfs_ilock(XFS_I(inode), XFS_MMAPLOCK_SHARED); > + filemap_map_pages(vmf, start_pgoff, end_pgoff); > + xfs_iunlock(XFS_I(inode), XFS_MMAPLOCK_SHARED); > +} > + > static const struct vm_operations_struct xfs_file_vm_ops = { > .fault = xfs_filemap_fault, > .huge_fault = xfs_filemap_huge_fault, > - .map_pages = filemap_map_pages, > + .map_pages = xfs_filemap_map_pages, > .page_mkwrite = xfs_filemap_page_mkwrite, > .pfn_mkwrite = xfs_filemap_pfn_mkwrite, > }; > -- > 2.26.2.761.g0e0b3e54be >