| 1 | #ifndef _LINUX_SWAP_H |
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| 2 | #define _LINUX_SWAP_H |
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| 3 | |
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| 4 | #include <linux/linkage.h> |
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| 5 | #include <linux/mmzone.h> |
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| 6 | #include <linux/sched.h> |
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| 7 | #include <asm/atomic.h> |
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| 8 | #include <asm/page.h> |
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| 9 | |
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| 10 | #define SWAP_FLAG_PREFER 0x8000 /* set if swap priority specified */ |
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| 11 | #define SWAP_FLAG_PRIO_MASK 0x7fff |
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| 12 | #define SWAP_FLAG_PRIO_SHIFT 0 |
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| 13 | |
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| 14 | static inline int current_is_kswapd(void) |
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| 15 | { |
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| 16 | return current->flags & PF_KSWAPD; |
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| 17 | } |
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| 18 | |
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| 19 | /* |
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| 20 | * MAX_SWAPFILES defines the maximum number of swaptypes: things which can |
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| 21 | * be swapped to. The swap type and the offset into that swap type are |
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| 22 | * encoded into pte's and into pgoff_t's in the swapcache. Using five bits |
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| 23 | * for the type means that the maximum number of swapcache pages is 27 bits |
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| 24 | * on 32-bit-pgoff_t architectures. And that assumes that the architecture packs |
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| 25 | * the type/offset into the pte as 5/27 as well. |
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| 26 | */ |
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| 27 | #define MAX_SWAPFILES_SHIFT 5 |
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| 28 | #define MAX_SWAPFILES (1 << MAX_SWAPFILES_SHIFT) |
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| 29 | |
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| 30 | /* |
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| 31 | * Magic header for a swap area. The first part of the union is |
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| 32 | * what the swap magic looks like for the old (limited to 128MB) |
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| 33 | * swap area format, the second part of the union adds - in the |
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| 34 | * old reserved area - some extra information. Note that the first |
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| 35 | * kilobyte is reserved for boot loader or disk label stuff... |
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| 36 | * |
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| 37 | * Having the magic at the end of the PAGE_SIZE makes detecting swap |
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| 38 | * areas somewhat tricky on machines that support multiple page sizes. |
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| 39 | * For 2.5 we'll probably want to move the magic to just beyond the |
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| 40 | * bootbits... |
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| 41 | */ |
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| 42 | union swap_header { |
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| 43 | struct { |
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| 44 | char reserved[PAGE_SIZE - 10]; |
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| 45 | char magic[10]; /* SWAP-SPACE or SWAPSPACE2 */ |
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| 46 | } magic; |
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| 47 | struct { |
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| 48 | char bootbits[1024]; /* Space for disklabel etc. */ |
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| 49 | unsigned int version; |
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| 50 | unsigned int last_page; |
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| 51 | unsigned int nr_badpages; |
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| 52 | unsigned int padding[125]; |
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| 53 | unsigned int badpages[1]; |
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| 54 | } info; |
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| 55 | }; |
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| 56 | |
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| 57 | /* A swap entry has to fit into a "unsigned long", as |
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| 58 | * the entry is hidden in the "index" field of the |
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| 59 | * swapper address space. |
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| 60 | */ |
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| 61 | typedef struct { |
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| 62 | unsigned long val; |
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| 63 | } swp_entry_t; |
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| 64 | |
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| 65 | /* |
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| 66 | * current->reclaim_state points to one of these when a task is running |
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| 67 | * memory reclaim |
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| 68 | */ |
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| 69 | struct reclaim_state { |
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| 70 | unsigned long reclaimed_slab; |
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| 71 | }; |
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| 72 | |
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| 73 | #endif /* _LINUX_SWAP_H */ |
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