Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 5a0dc736 authored by Yongqiang Yang's avatar Yongqiang Yang Committed by Theodore Ts'o
Browse files

ext4: handle EOF correctly in ext4_bio_write_page() 



We need to zero out part of a page which beyond EOF before setting uptodate,
otherwise, mapread or write will see non-zero data beyond EOF.

Signed-off-by: default avatarYongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
parent 5b5ffa49

fs/ext4/page-io.c

+12 −0
Original line number Diff line number Diff line
@@ -385,6 +385,18 @@ int ext4_bio_write_page(struct ext4_io_submit *io, 


		block_end = block_start + blocksize;

		if (block_start >= len) {

			/*

			 * Comments copied from block_write_full_page_endio:

			 *

			 * The page straddles i_size.  It must be zeroed out on

			 * each and every writepage invocation because it may

			 * be mmapped.  "A file is mapped in multiples of the

			 * page size.  For a file that is not a multiple of

			 * the  page size, the remaining memory is zeroed when

			 * mapped, and writes to that region are not written

			 * out to the file."

			 */

			zero_user_segment(page, block_start, block_end);

			clear_buffer_dirty(bh);

			set_buffer_uptodate(bh);

			continue;