Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751208AbdCRDvU (ORCPT ); Fri, 17 Mar 2017 23:51:20 -0400 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:46840 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751047AbdCRDvT (ORCPT ); Fri, 17 Mar 2017 23:51:19 -0400 Smtp-Origin-Hostprefix: devbig From: Calvin Owens Smtp-Origin-Hostname: devbig337.prn1.facebook.com To: "Darrick J. Wong" CC: , , Christoph Hellwig , Dave Chinner , , Smtp-Origin-Cluster: prn1c29 Subject: [PATCH] xfs: Honor FALLOC_FL_KEEP_SIZE when punching ends of files Date: Fri, 17 Mar 2017 18:24:48 -0700 Message-ID: <22a11e65fd5037498a78de61f3ed4dae466ad854.1489791330.git.calvinowens@fb.com> X-Mailer: git-send-email 2.9.3 X-FB-Internal: Safe MIME-Version: 1.0 Content-Type: text/plain X-Proofpoint-Spam-Reason: safe X-FB-Internal: Safe X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-03-17_21:,, signatures=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1762 Lines: 51 Commit 3c2bdc912a1cc050 ("xfs: kill xfs_zero_remaining_bytes") replaced xfs_zero_remaining_bytes() with calls to iomap helpers. Unfortunately the new iomap helpers don't enforce that [pos,count) lies strictly on [0,i_size). This causes fallocate(mode=PUNCH_HOLE|KEEP_SIZE) calls touching [i_size & ~PAGE_MASK, OFF_T_MAX] to round i_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 Fix this by reintroducing the checks xfs_zero_remaining_bytes() did against i_size into xfs_zero_range(). Reported-by: Aaron Gao Fixes: 3c2bdc912a1cc050 ("xfs: kill xfs_zero_remaining_bytes") Cc: Christoph Hellwig Cc: # 4.8+ Signed-off-by: Calvin Owens --- fs/xfs/xfs_file.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index 35703a8..da7cd27 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -58,6 +58,17 @@ xfs_zero_range( xfs_off_t count, bool *did_zero) { + /* + * Avoid doing I/O beyond eof - it's not necessary + * since nothing can read beyond eof. The space will + * be zeroed when the file is extended anyway. + */ + if (pos >= XFS_ISIZE(ip)) + return 0; + + if ((pos + count) >= XFS_ISIZE(ip)) + count = XFS_ISIZE(ip) - pos - 1; + return iomap_zero_range(VFS_I(ip), pos, count, NULL, &xfs_iomap_ops); } -- 2.9.3