include/linux/zpool.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * zpool memory storage api
   4  *
   5  * Copyright (C) 2014 Dan Streetman
   6  *
   7  * This is a common frontend for the zbud and zsmalloc memory
   8  * storage pool implementations.  Typically, this is used to
   9  * store compressed memory.
  10  */
  11
  12 #ifndef _ZPOOL_H_
  13 #define _ZPOOL_H_
  14
  15 struct zpool;
  16
  17 struct zpool_ops {
  18         int (*evict)(struct zpool *pool, unsigned long handle);
  19 };
  20
  21 /*
  22  * Control how a handle is mapped.  It will be ignored if the
  23  * implementation does not support it.  Its use is optional.
  24  * Note that this does not refer to memory protection, it
  25  * refers to how the memory will be copied in/out if copying
  26  * is necessary during mapping; read-write is the safest as
  27  * it copies the existing memory in on map, and copies the
  28  * changed memory back out on unmap.  Write-only does not copy
  29  * in the memory and should only be used for initialization.
  30  * If in doubt, use ZPOOL_MM_DEFAULT which is read-write.
  31  */
  32 enum zpool_mapmode {
  33         ZPOOL_MM_RW, /* normal read-write mapping */
  34         ZPOOL_MM_RO, /* read-only (no copy-out at unmap time) */
  35         ZPOOL_MM_WO, /* write-only (no copy-in at map time) */
  36
  37         ZPOOL_MM_DEFAULT = ZPOOL_MM_RW
  38 };
  39
  40 bool zpool_has_pool(char *type);
  41
  42 struct zpool *zpool_create_pool(const char *type, const char *name,
  43                         gfp_t gfp, const struct zpool_ops *ops);
  44
  45 const char *zpool_get_type(struct zpool *pool);
  46
  47 void zpool_destroy_pool(struct zpool *pool);
  48
  49 int zpool_malloc(struct zpool *pool, size_t size, gfp_t gfp,
  50                         unsigned long *handle);
  51
  52 void zpool_free(struct zpool *pool, unsigned long handle);
  53
  54 int zpool_shrink(struct zpool *pool, unsigned int pages,
  55                         unsigned int *reclaimed);
  56
  57 void *zpool_map_handle(struct zpool *pool, unsigned long handle,
  58                         enum zpool_mapmode mm);
  59
  60 void zpool_unmap_handle(struct zpool *pool, unsigned long handle);
  61
  62 u64 zpool_get_total_size(struct zpool *pool);
  63
  64
  65 /**
  66  * struct zpool_driver - driver implementation for zpool
  67  * @type:       name of the driver.
  68  * @list:       entry in the list of zpool drivers.
  69  * @create:     create a new pool.
  70  * @destroy:    destroy a pool.
  71  * @malloc:     allocate mem from a pool.
  72  * @free:       free mem from a pool.
  73  * @shrink:     shrink the pool.
  74  * @map:        map a handle.
  75  * @unmap:      unmap a handle.
  76  * @total_size: get total size of a pool.
  77  *
  78  * This is created by a zpool implementation and registered
  79  * with zpool.
  80  */
  81 struct zpool_driver {
  82         char *type;
  83         struct module *owner;
  84         atomic_t refcount;
  85         struct list_head list;
  86
  87         void *(*create)(const char *name,
  88                         gfp_t gfp,
  89                         const struct zpool_ops *ops,
  90                         struct zpool *zpool);
  91         void (*destroy)(void *pool);
  92
  93         int (*malloc)(void *pool, size_t size, gfp_t gfp,
  94                                 unsigned long *handle);
  95         void (*free)(void *pool, unsigned long handle);
  96
  97         int (*shrink)(void *pool, unsigned int pages,
  98                                 unsigned int *reclaimed);
  99
 100         void *(*map)(void *pool, unsigned long handle,
 101                                 enum zpool_mapmode mm);
 102         void (*unmap)(void *pool, unsigned long handle);
 103
 104         u64 (*total_size)(void *pool);
 105 };
 106
 107 void zpool_register_driver(struct zpool_driver *driver);
 108
 109 int zpool_unregister_driver(struct zpool_driver *driver);
 110
 111 bool zpool_evictable(struct zpool *pool);
 112
 113 #endif