123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125 |
- /*
- * 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_MIGRATION
- static 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)
- static inline int is_migration_entry(swp_entry_t swp)
- {
- return 0;
- }
- #define migration_entry_to_page(swp) NULL
- static 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
|