[Ocfs2-devel] [PATCH v5] ocfs2: Don't duplicate page passes i_size during CoW.

[Tao Ma]

During CoW, actually all the pages after i_size contains
garbage data, so don't read and duplicate them.

Signed-off-by: Tao Ma <tao.ma at oracle.com>
---
 fs/ocfs2/refcounttree.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c
index 1cf9cda..5e03db2 100644
--- a/fs/ocfs2/refcounttree.c
+++ b/fs/ocfs2/refcounttree.c
@@ -2931,6 +2931,12 @@ static int ocfs2_duplicate_clusters_by_page(handle_t *handle,
 
 	offset = ((loff_t)cpos) << OCFS2_SB(sb)->s_clustersize_bits;
 	end = offset + (new_len << OCFS2_SB(sb)->s_clustersize_bits);
+	/*
+	 * We only duplicate pages until we reach the page contains i_size - 1.
+	 * So trim 'end' to i_size.
+	 */
+	if (end > i_size_read(context->inode))
+		end = i_size_read(context->inode);
 
 	while (offset < end) {
 		page_index = offset >> PAGE_CACHE_SHIFT;
-- 
1.7.1.571.gba4d01