[PATCH] alpha: file offset in pte

It's possible to squeeze more bits out of lower half of pte,
but 32 seem to be a plenty...

Ivan.

include/asm-alpha/pgtable.h

@@ -68,6 +68,7 @@
 /* .. and these are ours ... */
 #define _PAGE_DIRTY	0x20000
 #define _PAGE_ACCESSED	0x40000
+#define _PAGE_FILE	0x80000	/* pagecache or swap? */
 
 /*
  * NOTE! The "accessed" bit isn't necessarily exact:  it can be kept exactly
@@ -254,6 +255,7 @@ extern inline int pte_write(pte_t pte)		{ return !(pte_val(pte) & _PAGE_FOW); }
 extern inline int pte_exec(pte_t pte)		{ return !(pte_val(pte) & _PAGE_FOE); }
 extern inline int pte_dirty(pte_t pte)		{ return pte_val(pte) & _PAGE_DIRTY; }
 extern inline int pte_young(pte_t pte)		{ return pte_val(pte) & _PAGE_ACCESSED; }
+extern inline int pte_file(pte_t pte)		{ return pte_val(pte) & _PAGE_FILE; }
 
 extern inline pte_t pte_wrprotect(pte_t pte)	{ pte_val(pte) |= _PAGE_FOW; return pte; }
 extern inline pte_t pte_rdprotect(pte_t pte)	{ pte_val(pte) |= _PAGE_FOR; return pte; }
@@ -313,10 +315,15 @@ extern inline pte_t mk_swap_pte(unsigned long type, unsigned long offset)
 
 #define __swp_type(x)		(((x).val >> 32) & 0xff)
 #define __swp_offset(x)		((x).val >> 40)
-#define __swp_entry(type, offset)	((swp_entry_t) { pte_val(mk_swap_pte((type),(offset))) })
+#define __swp_entry(type, off)	((swp_entry_t) { pte_val(mk_swap_pte((type), (off))) })
 #define __pte_to_swp_entry(pte)	((swp_entry_t) { pte_val(pte) })
 #define __swp_entry_to_pte(x)	((pte_t) { (x).val })
 
+#define pte_to_pgoff(pte)	(pte_val(pte) >> 32)
+#define pgoff_to_pte(off)	((pte_t) { ((off) << 32) | _PAGE_FILE })
+
+#define PTE_FILE_MAX_BITS	32
+
 #ifndef CONFIG_DISCONTIGMEM
 #define kern_addr_valid(addr)	(1)
 #endif