[PATCH 5.4 08/40] ocfs2: fix zero out valid data

[Greg Kroah-Hartman]

From: Junxiao Bi <junxiao.bi@xxxxxxxxxx>

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@xxxxxxxxxx
Fixes: 6bba4471f0cc ("ocfs2: fix data corruption by fallocate")
Signed-off-by: Junxiao Bi <junxiao.bi@xxxxxxxxxx>
Reviewed-by: Joseph Qi <joseph.qi@xxxxxxxxxxxxxxxxx>
Cc: Changwei Ge <gechangwei@xxxxxxx>
Cc: Gang He <ghe@xxxxxxxx>
Cc: Joel Becker <jlbec@xxxxxxxxxxxx>
Cc: Jun Piao <piaojun@xxxxxxxxxx>
Cc: Mark Fasheh <mark@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 fs/ocfs2/file.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -1935,7 +1935,6 @@ 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;
@@ -1943,7 +1942,7 @@ 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;
@@ -1998,6 +1997,7 @@ 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,