ocfs2: make room for unwritten extents flag
Due to the size of our group bitmaps, we'll never have a leaf node extent
record with more than 16 bits worth of clusters. Split e_clusters up so that
leaf nodes can get a flags field where we can mark unwritten extents.
Interior nodes whose length references all the child nodes beneath it can't
split their e_clusters field, so we use a union to preserve sizing there.
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
diff --git a/fs/ocfs2/alloc.h b/fs/ocfs2/alloc.h
index 3cb39cd..fbcb593 100644
--- a/fs/ocfs2/alloc.h
+++ b/fs/ocfs2/alloc.h
@@ -85,4 +85,23 @@
int ocfs2_find_leaf(struct inode *inode, struct ocfs2_extent_list *root_el,
u32 cpos, struct buffer_head **leaf_bh);
+/*
+ * Helper function to look at the # of clusters in an extent record.
+ */
+static inline unsigned int ocfs2_rec_clusters(struct ocfs2_extent_list *el,
+ struct ocfs2_extent_rec *rec)
+{
+ /*
+ * Cluster count in extent records is slightly different
+ * between interior nodes and leaf nodes. This is to support
+ * unwritten extents which need a flags field in leaf node
+ * records, thus shrinking the available space for a clusters
+ * field.
+ */
+ if (el->l_tree_depth)
+ return le32_to_cpu(rec->e_int_clusters);
+ else
+ return le16_to_cpu(rec->e_leaf_clusters);
+}
+
#endif /* OCFS2_ALLOC_H */