drivers/md/dm-memcache.h

   1 /*
   2  * Copyright (C) 2006-2008 Red Hat, Inc. All rights reserved.
   3  *
   4  * Module Author: Heinz Mauelshagen <Mauelshagen@RedHat.com>
   5  *
   6  * Device-mapper memory object handling:
   7  *
   8  * o allocate/free total_pages in a per client page pool.
   9  *
  10  * o allocate/free memory objects with chunks (1..n) of
  11  *   pages_per_chunk pages hanging off.
  12  *
  13  * This file is released under the GPL.
  14  */
  15
  16 #ifndef _DM_MEM_CACHE_H
  17 #define _DM_MEM_CACHE_H
  18
  19 #define DM_MEM_CACHE_H_VERSION  "0.1"
  20
  21 #include "dm.h"
  22 #include <linux/dm-io.h>
  23
  24 static inline struct page_list *pl_elem(struct page_list *pl, unsigned p)
  25 {
  26         while (pl && p--)
  27                 pl = pl->next;
  28
  29         return pl;
  30 }
  31
  32 struct dm_mem_cache_object {
  33         struct page_list *pl; /* Dynamically allocated array */
  34         void *private;        /* Caller context reference */
  35 };
  36
  37 struct dm_mem_cache_client;
  38
  39 /*
  40  * Create/destroy dm memory cache client resources.
  41  *
  42  * On creation, a number of @objects with @chunks of
  43  * @pages_per_chunk pages will be allocated.
  44  */
  45 struct dm_mem_cache_client *
  46 dm_mem_cache_client_create(unsigned objects, unsigned chunks,
  47                            unsigned pages_per_chunk);
  48 void dm_mem_cache_client_destroy(struct dm_mem_cache_client *client);
  49
  50 /*
  51  * Grow/shrink a dm memory cache client resources
  52  * by @objetcs amount of objects.
  53  */
  54 int dm_mem_cache_grow(struct dm_mem_cache_client *client, unsigned objects);
  55 int dm_mem_cache_shrink(struct dm_mem_cache_client *client, unsigned objects);
  56
  57 /*
  58  * Allocate/free a memory object
  59  *
  60  * On allocation one object with an amount of chunks and
  61  * an amount of pages per chunk will be returned on success.
  62  */
  63 struct dm_mem_cache_object *
  64 dm_mem_cache_alloc(struct dm_mem_cache_client *client);
  65 void dm_mem_cache_free(struct dm_mem_cache_client *client,
  66                        struct dm_mem_cache_object *object);
  67
  68 #endif