diff --git a/mm/filemap.c b/mm/filemap.c
index c1b9405..b436cbb 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -593,7 +593,7 @@
  * Is there a pagecache struct page at the given (mapping, offset) tuple?
  * If yes, increment its refcount and return it; if no, return NULL.
  */
-struct page * find_get_page(struct address_space *mapping, unsigned long offset)
+struct page * find_get_page(struct address_space *mapping, pgoff_t offset)
 {
 	struct page *page;
 
@@ -617,7 +617,7 @@
  * Returns zero if the page was not present. find_lock_page() may sleep.
  */
 struct page *find_lock_page(struct address_space *mapping,
-				unsigned long offset)
+				pgoff_t offset)
 {
 	struct page *page;
 
@@ -663,7 +663,7 @@
  * memory exhaustion.
  */
 struct page *find_or_create_page(struct address_space *mapping,
-		unsigned long index, gfp_t gfp_mask)
+		pgoff_t index, gfp_t gfp_mask)
 {
 	struct page *page, *cached_page = NULL;
 	int err;
@@ -797,7 +797,7 @@
  * and deadlock against the caller's locked page.
  */
 struct page *
-grab_cache_page_nowait(struct address_space *mapping, unsigned long index)
+grab_cache_page_nowait(struct address_space *mapping, pgoff_t index)
 {
 	struct page *page = find_get_page(mapping, index);
 
@@ -866,10 +866,10 @@
 			     read_actor_t actor)
 {
 	struct inode *inode = mapping->host;
-	unsigned long index;
-	unsigned long offset;
-	unsigned long last_index;
-	unsigned long prev_index;
+	pgoff_t index;
+	pgoff_t last_index;
+	pgoff_t prev_index;
+	unsigned long offset;      /* offset into pagecache page */
 	unsigned int prev_offset;
 	struct page *cached_page;
 	int error;
@@ -883,7 +883,7 @@
 
 	for (;;) {
 		struct page *page;
-		unsigned long end_index;
+		pgoff_t end_index;
 		loff_t isize;
 		unsigned long nr, ret;
 
@@ -1217,7 +1217,7 @@
 
 static ssize_t
 do_readahead(struct address_space *mapping, struct file *filp,
-	     unsigned long index, unsigned long nr)
+	     pgoff_t index, unsigned long nr)
 {
 	if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage)
 		return -EINVAL;
@@ -1237,8 +1237,8 @@
 	if (file) {
 		if (file->f_mode & FMODE_READ) {
 			struct address_space *mapping = file->f_mapping;
-			unsigned long start = offset >> PAGE_CACHE_SHIFT;
-			unsigned long end = (offset + count - 1) >> PAGE_CACHE_SHIFT;
+			pgoff_t start = offset >> PAGE_CACHE_SHIFT;
+			pgoff_t end = (offset + count - 1) >> PAGE_CACHE_SHIFT;
 			unsigned long len = end - start + 1;
 			ret = do_readahead(mapping, file, start, len);
 		}
@@ -1256,7 +1256,7 @@
  * This adds the requested page to the page cache if it isn't already there,
  * and schedules an I/O to read in its contents from disk.
  */
-static int fastcall page_cache_read(struct file * file, unsigned long offset)
+static int fastcall page_cache_read(struct file * file, pgoff_t offset)
 {
 	struct address_space *mapping = file->f_mapping;
 	struct page *page; 
@@ -1497,7 +1497,7 @@
 EXPORT_SYMBOL(generic_file_readonly_mmap);
 
 static struct page *__read_cache_page(struct address_space *mapping,
-				unsigned long index,
+				pgoff_t index,
 				int (*filler)(void *,struct page*),
 				void *data)
 {
@@ -1538,7 +1538,7 @@
  * after submitting it to the filler.
  */
 struct page *read_cache_page_async(struct address_space *mapping,
-				unsigned long index,
+				pgoff_t index,
 				int (*filler)(void *,struct page*),
 				void *data)
 {
@@ -1586,7 +1586,7 @@
  * If the page does not get brought uptodate, return -EIO.
  */
 struct page *read_cache_page(struct address_space *mapping,
-				unsigned long index,
+				pgoff_t index,
 				int (*filler)(void *,struct page*),
 				void *data)
 {