[PATCH 4.4 13/26] ocfs2: fix zero out valid data

Greg Kroah-Hartman
2021-08-02T13:46:13Z

From: Junxiao Bi <junxiao.bi@oracle.com>

commit f267aeb6dea5e468793e5b8eb6a9c72c0020d418 upstream.

If append-dio feature is enabled, direct-io write and fallocate could
run in parallel to extend file size, fallocate used "orig_isize" to
record i_size before taking "ip_alloc_sem", when
ocfs2_zeroout_partial_cluster() zeroout EOF blocks, i_size maybe already
extended by ocfs2_dio_end_io_write(), that will cause valid data zeroed
out.

Link: https://lkml.kernel.org/r/20210722054923.24389-1-junxiao.bi@oracle.com
Fixes: 6bba4471f0cc ("ocfs2: fix data corruption by fallocate")
Signed-off-by: Junxiao Bi <junxiao.bi@oracle.com>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Gang He <ghe@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Jun Piao <piaojun@huawei.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/ocfs2/file.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -1939,7 +1939,6 @@ static int __ocfs2_change_file_space(str
goto out_inode_unlock;
}

- orig_isize = i_size_read(inode);
switch (sr->l_whence) {
case 0: /*SEEK_SET*/
break;
@@ -1947,7 +1946,7 @@ static int __ocfs2_change_file_space(str
sr->l_start += f_pos;
break;
case 2: /*SEEK_END*/
- sr->l_start += orig_isize;
+ sr->l_start += i_size_read(inode);
break;
default:
ret = -EINVAL;
@@ -2002,6 +2001,7 @@ static int __ocfs2_change_file_space(str
ret = -EINVAL;
}

+ orig_isize = i_size_read(inode);
/* zeroout eof blocks in the cluster. */
if (!ret && change_size && orig_isize < size) {
ret = ocfs2_zeroout_partial_cluster(inode, orig_isize,