Commit 272b62c1 authored Feb 17, 2011 by Goldwyn Rodrigues Committed by Joel Becker Mar 28, 2011

Treat writes as new when holes span across page boundaries



When a hole spans across page boundaries, the next write forces
a read of the block. This could end up reading existing garbage
data from the disk in ocfs2_map_page_blocks. This leads to
non-zero holes. In order to avoid this, mark the writes as new
when the holes span across page boundaries.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.de>
Signed-off-by: jlbec <jlbec@evilplan.org>

parent 99bdc388

fs/ocfs2/aops.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -1015,6 +1015,12 @@ static int ocfs2_prepare_page_for_write(struct inode inode, u64 p_blkno,
		ocfs2_figure_cluster_boundaries(OCFS2_SB(inode->i_sb), cpos,
		&cluster_start, &cluster_end);

		/* treat the write as new if the a hole/lseek spanned across
		* the page boundary.
		*/
		new = new \| ((i_size_read(inode) <= page_offset(page)) &&
		(page_offset(page) <= user_pos));

		if (page == wc->w_target_page) {
		map_from = user_pos & (PAGE_CACHE_SIZE - 1);
		map_to = map_from + user_len;