drivers/staging/zram/xvmalloc_int.h

   1 /*
   2  * xvmalloc memory allocator
   3  *
   4  * Copyright (C) 2008, 2009, 2010  Nitin Gupta
   5  *
   6  * This code is released using a dual license strategy: BSD/GPL
   7  * You can choose the licence that better fits your requirements.
   8  *
   9  * Released under the terms of 3-clause BSD License
  10  * Released under the terms of GNU General Public License Version 2.0
  11  */
  12
  13 #ifndef _XV_MALLOC_INT_H_
  14 #define _XV_MALLOC_INT_H_
  15
  16 #include <linux/kernel.h>
  17 #include <linux/types.h>
  18
  19 /* User configurable params */
  20
  21 /* Must be power of two */
  22 #ifdef CONFIG_64BIT
  23 #define XV_ALIGN_SHIFT 3
  24 #else
  25 #define XV_ALIGN_SHIFT  2
  26 #endif
  27 #define XV_ALIGN        (1 << XV_ALIGN_SHIFT)
  28 #define XV_ALIGN_MASK   (XV_ALIGN - 1)
  29
  30 /* This must be greater than sizeof(link_free) */
  31 #define XV_MIN_ALLOC_SIZE       32
  32 #define XV_MAX_ALLOC_SIZE       (PAGE_SIZE - XV_ALIGN)
  33
  34 /*
  35  * Free lists are separated by FL_DELTA bytes
  36  * This value is 3 for 4k pages and 4 for 64k pages, for any
  37  * other page size, a conservative (PAGE_SHIFT - 9) is used.
  38  */
  39 #if PAGE_SHIFT == 16
  40 #define FL_DELTA_SHIFT 4
  41 #else
  42 #define FL_DELTA_SHIFT (PAGE_SHIFT - 9)
  43 #endif
  44 #define FL_DELTA        (1 << FL_DELTA_SHIFT)
  45 #define FL_DELTA_MASK   (FL_DELTA - 1)
  46 #define NUM_FREE_LISTS  ((XV_MAX_ALLOC_SIZE - XV_MIN_ALLOC_SIZE) \
  47                                 / FL_DELTA + 1)
  48
  49 #define MAX_FLI         DIV_ROUND_UP(NUM_FREE_LISTS, BITS_PER_LONG)
  50
  51 /* End of user params */
  52
  53 enum blockflags {
  54         BLOCK_FREE,
  55         PREV_FREE,
  56         __NR_BLOCKFLAGS,
  57 };
  58
  59 #define FLAGS_MASK      XV_ALIGN_MASK
  60 #define PREV_MASK       (~FLAGS_MASK)
  61
  62 struct freelist_entry {
  63         struct page *page;
  64         u16 offset;
  65         u16 pad;
  66 };
  67
  68 struct link_free {
  69         struct page *prev_page;
  70         struct page *next_page;
  71         u16 prev_offset;
  72         u16 next_offset;
  73 };
  74
  75 struct block_header {
  76         union {
  77                 /* This common header must be XV_ALIGN bytes */
  78                 u8 common[XV_ALIGN];
  79                 struct {
  80                         u16 size;
  81                         u16 prev;
  82                 };
  83         };
  84         struct link_free link;
  85 };
  86
  87 struct xv_pool {
  88         ulong flbitmap;
  89         ulong slbitmap[MAX_FLI];
  90         u64 total_pages;        /* stats */
  91         struct freelist_entry freelist[NUM_FREE_LISTS];
  92         spinlock_t lock;
  93 };
  94
  95 #endif