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Treat writes as new when holes span across page boundaries

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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>
This commit is contained in:
Goldwyn Rodrigues 2011-02-17 09:44:40 -06:00 committed by Joel Becker
parent 99bdc3880c
commit 272b62c1f0
1 changed files with 6 additions and 0 deletions
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6
fs/ocfs2/aops.c
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@ -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;