From 56809722764c76f0383dc3be872bca1cfa59c8d9 Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@suse.cz>
Date: Fri, 27 Jan 2017 14:35:38 -0500
Subject: [PATCH] ext4: fix data corruption in data=journal mode

commit 3b136499e906460919f0d21a49db1aaccf0ae963 upstream.

ext4_journalled_write_end() did not propely handle all the cases when
generic_perform_write() did not copy all the data into the target page
and could mark buffers with uninitialized contents as uptodate and dirty
leading to possible data corruption (which would be quickly fixed by
generic_perform_write() retrying the write but still). Fix the problem
by carefully handling the case when the page that is written to is not
uptodate.

Reported-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
Reading git-format-patch failed