[V2,1/2] ocfs2: fix zero out valid data

Commit Message

Junxiao Bi July 22, 2021, 5:49 a.m. UTC

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.

Fixes: 6bba4471f0cc ("ocfs2: fix data corruption by fallocate")
Signed-off-by: Junxiao Bi <[e-mail]>
Cc: <[e-mail]>
Reviewed-by: Joseph Qi <[e-mail]>
---
Changes in V2:
- fix commit id in the patch header

 fs/ocfs2/file.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Patch

diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index 775657943057..53bb46ce3cbb 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -1935,7 +1935,6 @@  static int __ocfs2_change_file_space(struct file *file, struct inode *inode,
 		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(struct file *file, struct inode *inode,
 		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(struct file *file, struct inode *inode,
 		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,