mm/zpool.c

   1 /*
   2  * zpool memory storage api
   3  *
   4  * Copyright (C) 2014 Dan Streetman
   5  *
   6  * This is a common frontend for memory storage pool implementations.
   7  * Typically, this is used to store compressed memory.
   8  */
   9
  10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  11
  12 #include <linux/list.h>
  13 #include <linux/types.h>
  14 #include <linux/mm.h>
  15 #include <linux/slab.h>
  16 #include <linux/spinlock.h>
  17 #include <linux/module.h>
  18 #include <linux/zpool.h>
  19
  20 struct zpool {
  21         char *type;
  22
  23         struct zpool_driver *driver;
  24         void *pool;
  25         struct zpool_ops *ops;
  26
  27         struct list_head list;
  28 };
  29
  30 static LIST_HEAD(drivers_head);
  31 static DEFINE_SPINLOCK(drivers_lock);
  32
  33 static LIST_HEAD(pools_head);
  34 static DEFINE_SPINLOCK(pools_lock);
  35
  36 void zpool_register_driver(struct zpool_driver *driver)
  37 {
  38         spin_lock(&drivers_lock);
  39         list_add(&driver->list, &drivers_head);
  40         spin_unlock(&drivers_lock);
  41 }
  42 EXPORT_SYMBOL(zpool_register_driver);
  43
  44 void zpool_unregister_driver(struct zpool_driver *driver)
  45 {
  46         spin_lock(&drivers_lock);
  47         list_del(&driver->list);
  48         spin_unlock(&drivers_lock);
  49 }
  50 EXPORT_SYMBOL(zpool_unregister_driver);
  51
  52 int zpool_evict(void *pool, unsigned long handle)
  53 {
  54         struct zpool *zpool;
  55
  56         spin_lock(&pools_lock);
  57         list_for_each_entry(zpool, &pools_head, list) {
  58                 if (zpool->pool == pool) {
  59                         spin_unlock(&pools_lock);
  60                         if (!zpool->ops || !zpool->ops->evict)
  61                                 return -EINVAL;
  62                         return zpool->ops->evict(zpool, handle);
  63                 }
  64         }
  65         spin_unlock(&pools_lock);
  66
  67         return -ENOENT;
  68 }
  69 EXPORT_SYMBOL(zpool_evict);
  70
  71 static struct zpool_driver *zpool_get_driver(char *type)
  72 {
  73         struct zpool_driver *driver;
  74
  75         assert_spin_locked(&drivers_lock);
  76         list_for_each_entry(driver, &drivers_head, list) {
  77                 if (!strcmp(driver->type, type))
  78                         return driver;
  79         }
  80
  81         return NULL;
  82 }
  83
  84 struct zpool *zpool_create_pool(char *type, gfp_t flags,
  85                         struct zpool_ops *ops)
  86 {
  87         struct zpool_driver *driver;
  88         struct zpool *zpool;
  89
  90         pr_info("creating pool type %s\n", type);
  91
  92         spin_lock(&drivers_lock);
  93         driver = zpool_get_driver(type);
  94         spin_unlock(&drivers_lock);
  95
  96         if (!driver) {
  97                 request_module(type);
  98                 spin_lock(&drivers_lock);
  99                 driver = zpool_get_driver(type);
 100                 spin_unlock(&drivers_lock);
 101         }
 102
 103         if (!driver) {
 104                 pr_err("no driver for type %s\n", type);
 105                 return NULL;
 106         }
 107
 108         zpool = kmalloc(sizeof(*zpool), GFP_KERNEL);
 109         if (!zpool) {
 110                 pr_err("couldn't create zpool - out of memory\n");
 111                 return NULL;
 112         }
 113
 114         zpool->type = driver->type;
 115         zpool->driver = driver;
 116         zpool->pool = driver->create(flags, ops);
 117         zpool->ops = ops;
 118
 119         if (!zpool->pool) {
 120                 pr_err("couldn't create %s pool\n", type);
 121                 kfree(zpool);
 122                 return NULL;
 123         }
 124
 125         pr_info("created %s pool\n", type);
 126
 127         spin_lock(&pools_lock);
 128         list_add(&zpool->list, &pools_head);
 129         spin_unlock(&pools_lock);
 130
 131         return zpool;
 132 }
 133
 134 void zpool_destroy_pool(struct zpool *zpool)
 135 {
 136         pr_info("destroying pool type %s\n", zpool->type);
 137
 138         spin_lock(&pools_lock);
 139         list_del(&zpool->list);
 140         spin_unlock(&pools_lock);
 141         zpool->driver->destroy(zpool->pool);
 142         kfree(zpool);
 143 }
 144
 145 char *zpool_get_type(struct zpool *zpool)
 146 {
 147         return zpool->type;
 148 }
 149
 150 int zpool_malloc(struct zpool *zpool, size_t size, unsigned long *handle)
 151 {
 152         return zpool->driver->malloc(zpool->pool, size, handle);
 153 }
 154
 155 void zpool_free(struct zpool *zpool, unsigned long handle)
 156 {
 157         zpool->driver->free(zpool->pool, handle);
 158 }
 159
 160 int zpool_shrink(struct zpool *zpool, unsigned int pages,
 161                         unsigned int *reclaimed)
 162 {
 163         return zpool->driver->shrink(zpool->pool, pages, reclaimed);
 164 }
 165
 166 void *zpool_map_handle(struct zpool *zpool, unsigned long handle,
 167                         enum zpool_mapmode mapmode)
 168 {
 169         return zpool->driver->map(zpool->pool, handle, mapmode);
 170 }
 171
 172 void zpool_unmap_handle(struct zpool *zpool, unsigned long handle)
 173 {
 174         zpool->driver->unmap(zpool->pool, handle);
 175 }
 176
 177 u64 zpool_get_total_size(struct zpool *zpool)
 178 {
 179         return zpool->driver->total_size(zpool->pool);
 180 }
 181
 182 static int __init init_zpool(void)
 183 {
 184         pr_info("loaded\n");
 185         return 0;
 186 }
 187
 188 static void __exit exit_zpool(void)
 189 {
 190         pr_info("unloaded\n");
 191 }
 192
 193 module_init(init_zpool);
 194 module_exit(exit_zpool);
 195
 196 MODULE_LICENSE("GPL");
 197 MODULE_AUTHOR("Dan Streetman <ddstreet@ieee.org>");
 198 MODULE_DESCRIPTION("Common API for compressed memory storage");