Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * swapcache pages are stored in the swapper_space radix tree. We want to |
| 3 | * get good packing density in that tree, so the index should be dense in |
| 4 | * the low-order bits. |
| 5 | * |
| 6 | * We arrange the `type' and `offset' fields so that `type' is at the five |
Paolo 'Blaisorblade' Giarrusso | e83a959 | 2005-09-03 15:54:53 -0700 | [diff] [blame] | 7 | * high-order bits of the swp_entry_t and `offset' is right-aligned in the |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 8 | * remaining bits. |
| 9 | * |
| 10 | * swp_entry_t's are *never* stored anywhere in their arch-dependent format. |
| 11 | */ |
| 12 | #define SWP_TYPE_SHIFT(e) (sizeof(e.val) * 8 - MAX_SWAPFILES_SHIFT) |
| 13 | #define SWP_OFFSET_MASK(e) ((1UL << SWP_TYPE_SHIFT(e)) - 1) |
| 14 | |
| 15 | /* |
| 16 | * Store a type+offset into a swp_entry_t in an arch-independent format |
| 17 | */ |
| 18 | static inline swp_entry_t swp_entry(unsigned long type, pgoff_t offset) |
| 19 | { |
| 20 | swp_entry_t ret; |
| 21 | |
| 22 | ret.val = (type << SWP_TYPE_SHIFT(ret)) | |
| 23 | (offset & SWP_OFFSET_MASK(ret)); |
| 24 | return ret; |
| 25 | } |
| 26 | |
| 27 | /* |
| 28 | * Extract the `type' field from a swp_entry_t. The swp_entry_t is in |
| 29 | * arch-independent format |
| 30 | */ |
| 31 | static inline unsigned swp_type(swp_entry_t entry) |
| 32 | { |
| 33 | return (entry.val >> SWP_TYPE_SHIFT(entry)); |
| 34 | } |
| 35 | |
| 36 | /* |
| 37 | * Extract the `offset' field from a swp_entry_t. The swp_entry_t is in |
| 38 | * arch-independent format |
| 39 | */ |
| 40 | static inline pgoff_t swp_offset(swp_entry_t entry) |
| 41 | { |
| 42 | return entry.val & SWP_OFFSET_MASK(entry); |
| 43 | } |
| 44 | |
Matt Mackall | 698dd4b | 2008-02-04 22:29:00 -0800 | [diff] [blame] | 45 | /* check whether a pte points to a swap entry */ |
| 46 | static inline int is_swap_pte(pte_t pte) |
| 47 | { |
| 48 | return !pte_none(pte) && !pte_present(pte) && !pte_file(pte); |
| 49 | } |
| 50 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 51 | /* |
| 52 | * Convert the arch-dependent pte representation of a swp_entry_t into an |
| 53 | * arch-independent swp_entry_t. |
| 54 | */ |
| 55 | static inline swp_entry_t pte_to_swp_entry(pte_t pte) |
| 56 | { |
| 57 | swp_entry_t arch_entry; |
| 58 | |
| 59 | BUG_ON(pte_file(pte)); |
| 60 | arch_entry = __pte_to_swp_entry(pte); |
| 61 | return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry)); |
| 62 | } |
| 63 | |
| 64 | /* |
| 65 | * Convert the arch-independent representation of a swp_entry_t into the |
| 66 | * arch-dependent pte representation. |
| 67 | */ |
| 68 | static inline pte_t swp_entry_to_pte(swp_entry_t entry) |
| 69 | { |
| 70 | swp_entry_t arch_entry; |
| 71 | |
| 72 | arch_entry = __swp_entry(swp_type(entry), swp_offset(entry)); |
| 73 | BUG_ON(pte_file(__swp_entry_to_pte(arch_entry))); |
| 74 | return __swp_entry_to_pte(arch_entry); |
| 75 | } |
Christoph Lameter | 0697212 | 2006-06-23 02:03:35 -0700 | [diff] [blame] | 76 | |
| 77 | #ifdef CONFIG_MIGRATION |
| 78 | static inline swp_entry_t make_migration_entry(struct page *page, int write) |
| 79 | { |
| 80 | BUG_ON(!PageLocked(page)); |
| 81 | return swp_entry(write ? SWP_MIGRATION_WRITE : SWP_MIGRATION_READ, |
| 82 | page_to_pfn(page)); |
| 83 | } |
| 84 | |
| 85 | static inline int is_migration_entry(swp_entry_t entry) |
| 86 | { |
| 87 | return unlikely(swp_type(entry) == SWP_MIGRATION_READ || |
| 88 | swp_type(entry) == SWP_MIGRATION_WRITE); |
| 89 | } |
| 90 | |
| 91 | static inline int is_write_migration_entry(swp_entry_t entry) |
| 92 | { |
| 93 | return unlikely(swp_type(entry) == SWP_MIGRATION_WRITE); |
| 94 | } |
| 95 | |
| 96 | static inline struct page *migration_entry_to_page(swp_entry_t entry) |
| 97 | { |
| 98 | struct page *p = pfn_to_page(swp_offset(entry)); |
| 99 | /* |
| 100 | * Any use of migration entries may only occur while the |
| 101 | * corresponding page is locked |
| 102 | */ |
| 103 | BUG_ON(!PageLocked(p)); |
| 104 | return p; |
| 105 | } |
| 106 | |
| 107 | static inline void make_migration_entry_read(swp_entry_t *entry) |
| 108 | { |
| 109 | *entry = swp_entry(SWP_MIGRATION_READ, swp_offset(*entry)); |
| 110 | } |
| 111 | |
| 112 | extern void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd, |
| 113 | unsigned long address); |
| 114 | #else |
| 115 | |
| 116 | #define make_migration_entry(page, write) swp_entry(0, 0) |
Andrew Morton | 5ec553a | 2007-02-20 13:57:50 -0800 | [diff] [blame] | 117 | static inline int is_migration_entry(swp_entry_t swp) |
| 118 | { |
| 119 | return 0; |
| 120 | } |
Christoph Lameter | 0697212 | 2006-06-23 02:03:35 -0700 | [diff] [blame] | 121 | #define migration_entry_to_page(swp) NULL |
| 122 | static inline void make_migration_entry_read(swp_entry_t *entryp) { } |
| 123 | static inline void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd, |
| 124 | unsigned long address) { } |
| 125 | static inline int is_write_migration_entry(swp_entry_t entry) |
| 126 | { |
| 127 | return 0; |
| 128 | } |
| 129 | |
| 130 | #endif |
| 131 | |