1 #ifndef _LINUX_SWAPOPS_H
2 #define _LINUX_SWAPOPS_H
4 #include <linux/radix-tree.h>
8 * swapcache pages are stored in the swapper_space radix tree. We want to
9 * get good packing density in that tree, so the index should be dense in
12 * We arrange the `type' and `offset' fields so that `type' is at the seven
13 * high-order bits of the swp_entry_t and `offset' is right-aligned in the
14 * remaining bits. Although `type' itself needs only five bits, we allow for
15 * shmem/tmpfs to shift it all up a further two bits: see swp_to_radix_entry().
17 * swp_entry_t's are *never* stored anywhere in their arch-dependent format.
19 #define SWP_TYPE_SHIFT(e) ((sizeof(e.val) * 8) - \
20 (MAX_SWAPFILES_SHIFT + RADIX_TREE_EXCEPTIONAL_SHIFT))
21 #define SWP_OFFSET_MASK(e) ((1UL << SWP_TYPE_SHIFT(e)) - 1)
24 * Store a type+offset into a swp_entry_t in an arch-independent format
26 static inline swp_entry_t swp_entry(unsigned long type, pgoff_t offset)
30 ret.val = (type << SWP_TYPE_SHIFT(ret)) |
31 (offset & SWP_OFFSET_MASK(ret));
36 * Extract the `type' field from a swp_entry_t. The swp_entry_t is in
37 * arch-independent format
39 static inline unsigned swp_type(swp_entry_t entry)
41 return (entry.val >> SWP_TYPE_SHIFT(entry));
45 * Extract the `offset' field from a swp_entry_t. The swp_entry_t is in
46 * arch-independent format
48 static inline pgoff_t swp_offset(swp_entry_t entry)
50 return entry.val & SWP_OFFSET_MASK(entry);
54 /* check whether a pte points to a swap entry */
55 static inline int is_swap_pte(pte_t pte)
57 return !pte_none(pte) && !pte_present_nonuma(pte);
62 * Convert the arch-dependent pte representation of a swp_entry_t into an
63 * arch-independent swp_entry_t.
65 static inline swp_entry_t pte_to_swp_entry(pte_t pte)
67 swp_entry_t arch_entry;
69 if (pte_swp_soft_dirty(pte))
70 pte = pte_swp_clear_soft_dirty(pte);
71 arch_entry = __pte_to_swp_entry(pte);
72 return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry));
76 * Convert the arch-independent representation of a swp_entry_t into the
77 * arch-dependent pte representation.
79 static inline pte_t swp_entry_to_pte(swp_entry_t entry)
81 swp_entry_t arch_entry;
83 arch_entry = __swp_entry(swp_type(entry), swp_offset(entry));
84 return __swp_entry_to_pte(arch_entry);
87 static inline swp_entry_t radix_to_swp_entry(void *arg)
91 entry.val = (unsigned long)arg >> RADIX_TREE_EXCEPTIONAL_SHIFT;
95 static inline void *swp_to_radix_entry(swp_entry_t entry)
99 value = entry.val << RADIX_TREE_EXCEPTIONAL_SHIFT;
100 return (void *)(value | RADIX_TREE_EXCEPTIONAL_ENTRY);
103 #ifdef CONFIG_MIGRATION
104 static inline swp_entry_t make_migration_entry(struct page *page, int write)
106 BUG_ON(!PageLocked(page));
107 return swp_entry(write ? SWP_MIGRATION_WRITE : SWP_MIGRATION_READ,
111 static inline int is_migration_entry(swp_entry_t entry)
113 return unlikely(swp_type(entry) == SWP_MIGRATION_READ ||
114 swp_type(entry) == SWP_MIGRATION_WRITE);
117 static inline int is_write_migration_entry(swp_entry_t entry)
119 return unlikely(swp_type(entry) == SWP_MIGRATION_WRITE);
122 static inline struct page *migration_entry_to_page(swp_entry_t entry)
124 struct page *p = pfn_to_page(swp_offset(entry));
126 * Any use of migration entries may only occur while the
127 * corresponding page is locked
129 BUG_ON(!PageLocked(p));
133 static inline void make_migration_entry_read(swp_entry_t *entry)
135 *entry = swp_entry(SWP_MIGRATION_READ, swp_offset(*entry));
138 extern void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
139 unsigned long address);
140 extern void migration_entry_wait_huge(struct vm_area_struct *vma,
141 struct mm_struct *mm, pte_t *pte);
144 #define make_migration_entry(page, write) swp_entry(0, 0)
145 static inline int is_migration_entry(swp_entry_t swp)
149 #define migration_entry_to_page(swp) NULL
150 static inline void make_migration_entry_read(swp_entry_t *entryp) { }
151 static inline void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
152 unsigned long address) { }
153 static inline void migration_entry_wait_huge(struct vm_area_struct *vma,
154 struct mm_struct *mm, pte_t *pte) { }
155 static inline int is_write_migration_entry(swp_entry_t entry)
162 #ifdef CONFIG_MEMORY_FAILURE
164 * Support for hardware poisoned pages
166 static inline swp_entry_t make_hwpoison_entry(struct page *page)
168 BUG_ON(!PageLocked(page));
169 return swp_entry(SWP_HWPOISON, page_to_pfn(page));
172 static inline int is_hwpoison_entry(swp_entry_t entry)
174 return swp_type(entry) == SWP_HWPOISON;
178 static inline swp_entry_t make_hwpoison_entry(struct page *page)
180 return swp_entry(0, 0);
183 static inline int is_hwpoison_entry(swp_entry_t swp)
189 #if defined(CONFIG_MEMORY_FAILURE) || defined(CONFIG_MIGRATION)
190 static inline int non_swap_entry(swp_entry_t entry)
192 return swp_type(entry) >= MAX_SWAPFILES;
195 static inline int non_swap_entry(swp_entry_t entry)
201 #endif /* _LINUX_SWAPOPS_H */