70 lines
1.9 KiB
C
70 lines
1.9 KiB
C
/*
|
|
* 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);
|
|
}
|