/* * swapcache pages are stored in the swapper_space radix tree.  We want to * get good packing density in that tree, so the index should be dense in * the low-order bits. * * We arrange the `type' and `offset' fields so that `type' is at the five * high-order bits of the swp_entry_t and `offset' is right-aligned in the * remaining bits. * * swp_entry_t's are *never* stored anywhere in their arch-dependent format. */#define SWP_TYPE_SHIFT(e)	(sizeof(e.val) * 8 - MAX_SWAPFILES_SHIFT)#define SWP_OFFSET_MASK(e)	((1UL << SWP_TYPE_SHIFT(e)) - 1)/* * Store a type+offset into a swp_entry_t in an arch-independent format */static inline swp_entry_t swp_entry(unsigned long type, pgoff_t offset){	swp_entry_t ret;	ret.val = (type << SWP_TYPE_SHIFT(ret)) |			(offset & SWP_OFFSET_MASK(ret));	return ret;}/* * Extract the `type' field from a swp_entry_t.  The swp_entry_t is in * arch-independent format */static inline unsigned swp_type(swp_entry_t entry){	return (entry.val >> SWP_TYPE_SHIFT(entry));}/* * Extract the `offset' field from a swp_entry_t.  The swp_entry_t is in * arch-independent format */static inline pgoff_t swp_offset(swp_entry_t entry){	return entry.val & SWP_OFFSET_MASK(entry);}/* * Convert the arch-dependent pte representation of a swp_entry_t into an * arch-independent swp_entry_t. */static inline swp_entry_t pte_to_swp_entry(pte_t pte){	swp_entry_t arch_entry;	BUG_ON(pte_file(pte));	arch_entry = __pte_to_swp_entry(pte);	return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry));}/* * Convert the arch-independent representation of a swp_entry_t into the * arch-dependent pte representation. */static inline pte_t swp_entry_to_pte(swp_entry_t entry){	swp_entry_t arch_entry;	arch_entry = __swp_entry(swp_type(entry), swp_offset(entry));	BUG_ON(pte_file(__swp_entry_to_pte(arch_entry)));	return __swp_entry_to_pte(arch_entry);}#ifdef CONFIG_MIGRATIONstatic inline swp_entry_t make_migration_entry(struct page *page, int write){	BUG_ON(!PageLocked(page));	return swp_entry(write ? SWP_MIGRATION_WRITE : SWP_MIGRATION_READ,			page_to_pfn(page));}static inline int is_migration_entry(swp_entry_t entry){	return unlikely(swp_type(entry) == SWP_MIGRATION_READ ||			swp_type(entry) == SWP_MIGRATION_WRITE);}static inline int is_write_migration_entry(swp_entry_t entry){	return unlikely(swp_type(entry) == SWP_MIGRATION_WRITE);}static inline struct page *migration_entry_to_page(swp_entry_t entry){	struct page *p = pfn_to_page(swp_offset(entry));	/*	 * Any use of migration entries may only occur while the	 * corresponding page is locked	 */	BUG_ON(!PageLocked(p));	return p;}static inline void make_migration_entry_read(swp_entry_t *entry){	*entry = swp_entry(SWP_MIGRATION_READ, swp_offset(*entry));}extern void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,					unsigned long address);#else#define make_migration_entry(page, write) swp_entry(0, 0)#define is_migration_entry(swp) 0#define migration_entry_to_page(swp) NULLstatic inline void make_migration_entry_read(swp_entry_t *entryp) { }static inline void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,					 unsigned long address) { }static inline int is_write_migration_entry(swp_entry_t entry){	return 0;}#endif