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

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
...@@ -385,6 +385,18 @@ int ext4_bio_write_page(struct ext4_io_submit *io, ...@@ -385,6 +385,18 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
block_end = block_start + blocksize; block_end = block_start + blocksize;
if (block_start >= len) { 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); clear_buffer_dirty(bh);
set_buffer_uptodate(bh); set_buffer_uptodate(bh);
continue; continue;
......
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