Messages in this thread Patch in this message | | | Date | Fri, 16 Dec 2011 11:40:45 -0800 | From | Greg KH <> | Subject | [38/45] ext4: handle EOF correctly in ext4_bio_write_page() |
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3.0-stable review patch. If anyone has any objections, please let me know.
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From: Yongqiang Yang <xiaoqiangnk@gmail.com>
commit 5a0dc7365c240795bf190766eba7a27600be3b3e upstream.
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: Yongqiang Yang <xiaoqiangnk@gmail.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- fs/ext4/page-io.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)
--- a/fs/ext4/page-io.c +++ b/fs/ext4/page-io.c @@ -405,6 +405,18 @@ int ext4_bio_write_page(struct ext4_io_s 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;
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