2.6.38-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Goldwyn Rodrigues <[email protected]>

commit 272b62c1f0f6f742046e45b50b6fec98860208a0 upstream.

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 <[email protected]>
Signed-off-by: jlbec <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

---
 fs/ocfs2/aops.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/fs/ocfs2/aops.c
+++ b/fs/ocfs2/aops.c
@@ -1026,6 +1026,12 @@ static int ocfs2_prepare_page_for_write(
        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;


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