1 files changed, 32 insertions, 0 deletions

diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h
index faeb53f2eecf..2699f7cac21a 100644
--- a/fs/ocfs2/ocfs2.h
+++ b/fs/ocfs2/ocfs2.h
@@ -463,6 +463,38 @@ static inline unsigned long ocfs2_align_bytes_to_sectors(u64 bytes)
         return (unsigned long)((bytes + 511) >> 9);
 }
 
+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;
+}
+
 #define ocfs2_set_bit ext2_set_bit
 #define ocfs2_clear_bit ext2_clear_bit
 #define ocfs2_test_bit ext2_test_bit