ext4: fix zeroing of page during writeback
authorJan Kara <jack@suse.cz>
Tue, 27 May 2014 16:48:55 +0000 (12:48 -0400)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Tue, 1 Jul 2014 03:09:42 +0000 (20:09 -0700)
commit327d2822e72d2f81adde6f8a8e5b9003634ae35a
tree3875cfdecb2e78679e3ba23366a7c57404337fef
parent07e6e46256b9168213f4aa8896618367876fd9d1
ext4: fix zeroing of page during writeback

commit eeece469dedadf3918bad50ad80f4616a0064e90 upstream.

Tail of a page straddling inode size must be zeroed when being written
out due to POSIX requirement that modifications of mmaped page beyond
inode size must not be written to the file. ext4_bio_write_page() did
this only for blocks fully beyond inode size but didn't properly zero
blocks partially beyond inode size. Fix this.

The problem has been uncovered by mmap_11-4 test in openposix test suite
(part of LTP).

Reported-by: Xiaoguang Wang <wangxg.fnst@cn.fujitsu.com>
Fixes: 5a0dc7365c240
Fixes: bd2d0210cf22f
CC: stable@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
fs/ext4/page-io.c