ocfs2: fix page zeroing during simple extends

The page zeroing code was missing the region between old i_size and new
i_size for those extends that didn't actually require a change in space
allocation.
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>

fs/ocfs2/file.c

@@ -728,10 +728,9 @@ static int ocfs2_extend_file(struct inode *inode,
 	clusters_to_add = ocfs2_clusters_for_bytes(inode->i_sb, new_i_size) - 
 		OCFS2_I(inode)->ip_clusters;
 
-	if (clusters_to_add) {
 	/* 
-		 * protect the pages that ocfs2_zero_extend is going to
-		 * be pulling into the page cache.. we do this before the
+	 * protect the pages that ocfs2_zero_extend is going to be
+	 * pulling into the page cache.. we do this before the
 	 * metadata extend so that we don't get into the situation
 	 * where we've extended the metadata but can't get the data
 	 * lock to zero.
@@ -742,18 +741,24 @@ static int ocfs2_extend_file(struct inode *inode,
 		goto out;
 	}
 
+	if (clusters_to_add) {
 		ret = ocfs2_extend_allocation(inode, clusters_to_add);
 		if (ret < 0) {
 			mlog_errno(ret);
 			goto out_unlock;
 		}
+	}
 
+	/*
+	 * Call this even if we don't add any clusters to the tree. We
+	 * still need to zero the area between the old i_size and the
+	 * new i_size.
+	 */
 	ret = ocfs2_zero_extend(inode, (u64)new_i_size - tail_to_skip);
 	if (ret < 0) {
 		mlog_errno(ret);
 		goto out_unlock;
 	}
-	}
 
 	if (!tail_to_skip) {
 		/* We're being called from ocfs2_setattr() which wants
@@ -764,7 +769,6 @@ static int ocfs2_extend_file(struct inode *inode,
 	}
 
 out_unlock:
-	if (clusters_to_add) /* this is the only case in which we lock */
 	ocfs2_data_unlock(inode, 1);
 
 out: