@@ -437,6 +437,17 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
ClearPageError(page);
/*
+ * 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."
+ */
+ if (len < PAGE_CACHE_SIZE)
+ zero_user_segment(page, len, PAGE_CACHE_SIZE);
+ /*
* In the first loop we prepare and mark buffers to submit. We have to
* mark all buffers in the page before submitting so that
* end_page_writeback() cannot be called from ext4_bio_end_io() when IO
@@ -447,19 +458,6 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
do {
block_start = bh_offset(bh);
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_start + blocksize);
clear_buffer_dirty(bh);
set_buffer_uptodate(bh);
continue;
This is a note to let you know that I have just added a patch titled ext4: fix zeroing of page during writeback to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.11.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From bc461339f2051b4f9e57d57b56293ecb7a44afc2 Mon Sep 17 00:00:00 2001 From: Jan Kara <jack@suse.cz> Date: Tue, 27 May 2014 12:48:55 -0400 Subject: 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 Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- fs/ext4/page-io.c | 24 +++++++++++------------- 1 file changed, 11 insertions(+), 13 deletions(-) -- 1.9.1