From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:37669 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750763AbdCaESV (ORCPT ); Fri, 31 Mar 2017 00:18:21 -0400 Date: Thu, 30 Mar 2017 21:18:00 -0700 From: Calvin Owens Subject: [PATCH v3] xfs: Honor FALLOC_FL_KEEP_SIZE when punching ends of files Message-ID: <20170331041800.ugi4wgmbqx44mbwa@Haydn> References: <22a11e65fd5037498a78de61f3ed4dae466ad854.1489791330.git.calvinowens@fb.com> <19504ff40a16efff2e51d85388fce5be578edbc3.1489985397.git.calvinowens@fb.com> <20170321113932.GA58653@bfoster.bfoster> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Disposition: inline In-Reply-To: Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: Brian Foster Cc: "Darrick J. Wong" , linux-xfs@vger.kernel.org, linux-kernel@vger.kernel.org, Christoph Hellwig , Dave Chinner , kernel-team@fb.com, stable@vger.kernel.org When punching past EOF on XFS, fallocate(mode=PUNCH_HOLE|KEEP_SIZE) will round the file size up to the nearest multiple of PAGE_SIZE: calvinow@vm-disks/generic-xfs-1 ~$ dd if=/dev/urandom of=test bs=2048 count=1 calvinow@vm-disks/generic-xfs-1 ~$ stat test Size: 2048 Blocks: 8 IO Block: 4096 regular file calvinow@vm-disks/generic-xfs-1 ~$ fallocate -n -l 2048 -o 2048 -p test calvinow@vm-disks/generic-xfs-1 ~$ stat test Size: 4096 Blocks: 8 IO Block: 4096 regular file Commit 3c2bdc912a1cc050 ("xfs: kill xfs_zero_remaining_bytes") replaced xfs_zero_remaining_bytes() with calls to iomap helpers. The new helpers don't enforce that [pos,offset) lies strictly on [0,i_size) when being called from xfs_free_file_space(), so by "leaking" these ranges into xfs_zero_range() we get this buggy behavior. Fix this by reintroducing the checks xfs_zero_remaining_bytes() did against i_size at the bottom of xfs_free_file_space(). Reported-by: Aaron Gao Fixes: 3c2bdc912a1cc050 ("xfs: kill xfs_zero_remaining_bytes") Cc: Christoph Hellwig Cc: Brian Foster Cc: # 4.8+ Signed-off-by: Calvin Owens --- fs/xfs/xfs_bmap_util.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c index 8b75dce..828532c 100644 --- a/fs/xfs/xfs_bmap_util.c +++ b/fs/xfs/xfs_bmap_util.c @@ -1311,8 +1311,16 @@ xfs_free_file_space( /* * Now that we've unmap all full blocks we'll have to zero out any * partial block at the beginning and/or end. xfs_zero_range is - * smart enough to skip any holes, including those we just created. + * smart enough to skip any holes, including those we just created, + * but we must take care not to zero beyond EOF and enlarge i_size. */ + + if (offset >= XFS_ISIZE(ip)) + return 0; + + if (offset + len > XFS_ISIZE(ip)) + len = XFS_ISIZE(ip) - offset; + return xfs_zero_range(ip, offset, len, NULL); } -- 2.9.3