From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from aserp2120.oracle.com ([141.146.126.78]:48020 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754253AbeFUSb4 (ORCPT ); Thu, 21 Jun 2018 14:31:56 -0400 Received: from pps.filterd (aserp2120.oracle.com [127.0.0.1]) by aserp2120.oracle.com (8.16.0.22/8.16.0.22) with SMTP id w5LITGuS013660 for ; Thu, 21 Jun 2018 18:31:55 GMT Received: from userv0022.oracle.com (userv0022.oracle.com [156.151.31.74]) by aserp2120.oracle.com with ESMTP id 2jmtgx3610-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Thu, 21 Jun 2018 18:31:55 +0000 Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by userv0022.oracle.com (8.14.4/8.14.4) with ESMTP id w5LIVsrt003422 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Thu, 21 Jun 2018 18:31:54 GMT Received: from abhmp0002.oracle.com (abhmp0002.oracle.com [141.146.116.8]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id w5LIVsKF028794 for ; Thu, 21 Jun 2018 18:31:54 GMT Subject: [PATCH 8/8] xfs: ensure post-EOF zeroing happens after zeroing part of a file From: "Darrick J. Wong" Date: Thu, 21 Jun 2018 11:31:53 -0700 Message-ID: <152960591330.26246.305971181988789033.stgit@magnolia> In-Reply-To: <152960586416.26246.8634761888260524091.stgit@magnolia> References: <152960586416.26246.8634761888260524091.stgit@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: darrick.wong@oracle.com Cc: linux-xfs@vger.kernel.org From: Darrick J. Wong If a user asks us to zero_range part of a file, the end of the range is EOF, and not aligned to a page boundary, invoke writeback of the EOF page to ensure that the post-EOF part of the page is zeroed. This ensures that we don't expose stale memory contents via mmap, if in a clumsy manner. Found by running generic/127 when it runs zero_range and mapread at EOF one after the other. Signed-off-by: Darrick J. Wong --- fs/xfs/xfs_bmap_util.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c index abc37b0899c0..c94d376e4152 100644 --- a/fs/xfs/xfs_bmap_util.c +++ b/fs/xfs/xfs_bmap_util.c @@ -1208,7 +1208,20 @@ xfs_free_file_space( return 0; if (offset + len > XFS_ISIZE(ip)) len = XFS_ISIZE(ip) - offset; - return iomap_zero_range(VFS_I(ip), offset, len, NULL, &xfs_iomap_ops); + error = iomap_zero_range(VFS_I(ip), offset, len, NULL, &xfs_iomap_ops); + if (error) + return error; + + /* + * If we zeroed right up to EOF and EOF straddles a page boundary we + * must make sure that the post-EOF area is also zeroed because the + * page could be mmap'd and iomap_zero_range doesn't do that for us. + * Writeback of the eof page will do this, albeit clumsily. + */ + if (offset + len < XFS_ISIZE(ip) || ((offset + len) & PAGE_MASK) == 0) + return 0; + return filemap_write_and_wait_range(VFS_I(ip)->i_mapping, + (offset + len) & ~PAGE_MASK, LLONG_MAX); } /*