ocfs2: Don't duplicate pages past i_size during CoW.

During CoW, the pages after i_size don't contain valid data, so there's
no need to read and duplicate them.

Signed-off-by: Tao Ma <tao.ma@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c
index 32949df10694..3ac5aa733e9c 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;