]>
git.proxmox.com Git - mirror_ubuntu-zesty-kernel.git/blob - include/linux/swapops.h
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
6 * We arrange the `type' and `offset' fields so that `type' is at the five
7 * high-order bits of the swp_entry_t and `offset' is right-aligned in the
10 * swp_entry_t's are *never* stored anywhere in their arch-dependent format.
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)
16 * Store a type+offset into a swp_entry_t in an arch-independent format
18 static inline swp_entry_t
swp_entry(unsigned long type
, pgoff_t offset
)
22 ret
.val
= (type
<< SWP_TYPE_SHIFT(ret
)) |
23 (offset
& SWP_OFFSET_MASK(ret
));
28 * Extract the `type' field from a swp_entry_t. The swp_entry_t is in
29 * arch-independent format
31 static inline unsigned swp_type(swp_entry_t entry
)
33 return (entry
.val
>> SWP_TYPE_SHIFT(entry
));
37 * Extract the `offset' field from a swp_entry_t. The swp_entry_t is in
38 * arch-independent format
40 static inline pgoff_t
swp_offset(swp_entry_t entry
)
42 return entry
.val
& SWP_OFFSET_MASK(entry
);
46 * Convert the arch-dependent pte representation of a swp_entry_t into an
47 * arch-independent swp_entry_t.
49 static inline swp_entry_t
pte_to_swp_entry(pte_t pte
)
51 swp_entry_t arch_entry
;
53 BUG_ON(pte_file(pte
));
54 arch_entry
= __pte_to_swp_entry(pte
);
55 return swp_entry(__swp_type(arch_entry
), __swp_offset(arch_entry
));
59 * Convert the arch-independent representation of a swp_entry_t into the
60 * arch-dependent pte representation.
62 static inline pte_t
swp_entry_to_pte(swp_entry_t entry
)
64 swp_entry_t arch_entry
;
66 arch_entry
= __swp_entry(swp_type(entry
), swp_offset(entry
));
67 BUG_ON(pte_file(__swp_entry_to_pte(arch_entry
)));
68 return __swp_entry_to_pte(arch_entry
);