ocfs2: Fix extent lookup to return true size of holes

Initially, we had wired things to return a size '1' of holes. Cook up a
small amount of code to find the next extent and calculate the number of
clusters between the virtual offset and the next allocated extent.

Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c
index db77e09..12d2340 100644
--- a/fs/ocfs2/journal.c
+++ b/fs/ocfs2/journal.c
@@ -649,9 +649,9 @@
 static int ocfs2_force_read_journal(struct inode *inode)
 {
 	int status = 0;
-	int i, p_blocks;
-	u64 v_blkno, p_blkno;
-#define CONCURRENT_JOURNAL_FILL 32
+	int i;
+	u64 v_blkno, p_blkno, p_blocks;
+#define CONCURRENT_JOURNAL_FILL 32ULL
 	struct buffer_head *bhs[CONCURRENT_JOURNAL_FILL];
 
 	mlog_entry_void();