include/linux/zpool.h

   1 /*
   2  * zpool memory storage api
   3  *
   4  * Copyright (C) 2014 Dan Streetman
   5  *
   6  * This is a common frontend for the zbud and zsmalloc memory
   7  * storage pool implementations.  Typically, this is used to
   8  * store compressed memory.
   9  */
  10
  11 #ifndef _ZPOOL_H_
  12 #define _ZPOOL_H_
  13
  14 struct zpool;
  15
  16 struct zpool_ops {
  17         int (*evict)(struct zpool *pool, unsigned long handle);
  18 };
  19
  20 /*
  21  * Control how a handle is mapped.  It will be ignored if the
  22  * implementation does not support it.  Its use is optional.
  23  * Note that this does not refer to memory protection, it
  24  * refers to how the memory will be copied in/out if copying
  25  * is necessary during mapping; read-write is the safest as
  26  * it copies the existing memory in on map, and copies the
  27  * changed memory back out on unmap.  Write-only does not copy
  28  * in the memory and should only be used for initialization.
  29  * If in doubt, use ZPOOL_MM_DEFAULT which is read-write.
  30  */
  31 enum zpool_mapmode {
  32         ZPOOL_MM_RW, /* normal read-write mapping */
  33         ZPOOL_MM_RO, /* read-only (no copy-out at unmap time) */
  34         ZPOOL_MM_WO, /* write-only (no copy-in at map time) */
  35
  36         ZPOOL_MM_DEFAULT = ZPOOL_MM_RW
  37 };
  38
  39 struct zpool *zpool_create_pool(char *type, char *name,
  40                         gfp_t gfp, struct zpool_ops *ops);
  41
  42 char *zpool_get_type(struct zpool *pool);
  43
  44 void zpool_destroy_pool(struct zpool *pool);
  45
  46 int zpool_malloc(struct zpool *pool, size_t size, gfp_t gfp,
  47                         unsigned long *handle);
  48
  49 void zpool_free(struct zpool *pool, unsigned long handle);
  50
  51 int zpool_shrink(struct zpool *pool, unsigned int pages,
  52                         unsigned int *reclaimed);
  53
  54 void *zpool_map_handle(struct zpool *pool, unsigned long handle,
  55                         enum zpool_mapmode mm);
  56
  57 void zpool_unmap_handle(struct zpool *pool, unsigned long handle);
  58
  59 u64 zpool_get_total_size(struct zpool *pool);
  60
  61
  62 /**
  63  * struct zpool_driver - driver implementation for zpool
  64  * @type:       name of the driver.
  65  * @list:       entry in the list of zpool drivers.
  66  * @create:     create a new pool.
  67  * @destroy:    destroy a pool.
  68  * @malloc:     allocate mem from a pool.
  69  * @free:       free mem from a pool.
  70  * @shrink:     shrink the pool.
  71  * @map:        map a handle.
  72  * @unmap:      unmap a handle.
  73  * @total_size: get total size of a pool.
  74  *
  75  * This is created by a zpool implementation and registered
  76  * with zpool.
  77  */
  78 struct zpool_driver {
  79         char *type;
  80         struct module *owner;
  81         atomic_t refcount;
  82         struct list_head list;
  83
  84         void *(*create)(char *name, gfp_t gfp, struct zpool_ops *ops);
  85         void (*destroy)(void *pool);
  86
  87         int (*malloc)(void *pool, size_t size, gfp_t gfp,
  88                                 unsigned long *handle);
  89         void (*free)(void *pool, unsigned long handle);
  90
  91         int (*shrink)(void *pool, unsigned int pages,
  92                                 unsigned int *reclaimed);
  93
  94         void *(*map)(void *pool, unsigned long handle,
  95                                 enum zpool_mapmode mm);
  96         void (*unmap)(void *pool, unsigned long handle);
  97
  98         u64 (*total_size)(void *pool);
  99 };
 100
 101 void zpool_register_driver(struct zpool_driver *driver);
 102
 103 int zpool_unregister_driver(struct zpool_driver *driver);
 104
 105 int zpool_evict(void *pool, unsigned long handle);
 106
 107 #endif