+static inline unsigned int ocfs2_page_index_to_clusters(struct super_block *sb,
+ unsigned long pg_index)
+{
+ u32 clusters = pg_index;
+ unsigned int cbits = OCFS2_SB(sb)->s_clustersize_bits;
+
+ if (unlikely(PAGE_CACHE_SHIFT > cbits))
+ clusters = pg_index << (PAGE_CACHE_SHIFT - cbits);
+ else if (PAGE_CACHE_SHIFT < cbits)
+ clusters = pg_index >> (cbits - PAGE_CACHE_SHIFT);
+
+ return clusters;
+}
+
+/*
+ * Find the 1st page index which covers the given clusters.
+ */
+static inline unsigned long ocfs2_align_clusters_to_page_index(struct super_block *sb,
+ u32 clusters)
+{
+ unsigned int cbits = OCFS2_SB(sb)->s_clustersize_bits;
+ unsigned long index = clusters;
+
+ if (PAGE_CACHE_SHIFT > cbits) {
+ index = clusters >> (PAGE_CACHE_SHIFT - cbits);
+ } else if (PAGE_CACHE_SHIFT < cbits) {
+ index = clusters << (cbits - PAGE_CACHE_SHIFT);
+ }
+
+ return index;
+}
+
+static inline unsigned int ocfs2_pages_per_cluster(struct super_block *sb)
+{
+ unsigned int cbits = OCFS2_SB(sb)->s_clustersize_bits;
+ unsigned int pages_per_cluster = 1;
+
+ if (PAGE_CACHE_SHIFT < cbits)
+ pages_per_cluster = 1 << (cbits - PAGE_CACHE_SHIFT);
+
+ return pages_per_cluster;
+}
+