Merge tag 'tytso-for-linus-20111214' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

* tag 'tytso-for-linus-20111214' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  ext4: handle EOF correctly in ext4_bio_write_page()
  ext4: remove a wrong BUG_ON in ext4_ext_convert_to_initialized
  ext4: correctly handle pages w/o buffers in ext4_discard_partial_buffers()
  ext4: avoid potential hang in mpage_submit_io() when blocksize < pagesize
  ext4: avoid hangs in ext4_da_should_update_i_disksize()
  ext4: display the correct mount option in /proc/mounts for [no]init_itable
  ext4: Fix crash due to getting bogus eh_depth value on big-endian systems
  ext4: fix ext4_end_io_dio() racing against fsync()

.. using the new signed tag merge of git that now verifies the gpg
signature automatically.  Yay.  The branchname was just 'dev', which is
prettier.  I'll tell Ted to use nicer tag names for future cases.

1 files changed, 12 insertions, 0 deletions

diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index 7ce1d0b19c9..7e106c810c6 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -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;