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authorYongqiang Yang <xiaoqiangnk@gmail.com>2011-12-13 22:29:12 -0500
committerTheodore Ts'o <tytso@mit.edu>2011-12-13 22:29:12 -0500
commit5a0dc7365c240795bf190766eba7a27600be3b3e (patch)
tree614d5275640f4df89604f64e2cd47a438644226e /fs/ext4/page-io.c
parent5b5ffa49d4bbb8ca4c41c094261660264f16bd20 (diff)
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: Yongqiang Yang <xiaoqiangnk@gmail.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Cc: stable@kernel.org
Diffstat (limited to 'fs/ext4/page-io.c')
-rw-r--r--fs/ext4/page-io.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index 7ce1d0b19c94..7e106c810c62 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;