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git.proxmox.com Git - mirror_ubuntu-zesty-kernel.git/blob - mm/zpool.c
2 * zpool memory storage api
4 * Copyright (C) 2014 Dan Streetman
6 * This is a common frontend for memory storage pool implementations.
7 * Typically, this is used to store compressed memory.
10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12 #include <linux/list.h>
13 #include <linux/types.h>
15 #include <linux/slab.h>
16 #include <linux/spinlock.h>
17 #include <linux/module.h>
18 #include <linux/zpool.h>
23 struct zpool_driver
*driver
;
25 struct zpool_ops
*ops
;
27 struct list_head list
;
30 static LIST_HEAD(drivers_head
);
31 static DEFINE_SPINLOCK(drivers_lock
);
33 static LIST_HEAD(pools_head
);
34 static DEFINE_SPINLOCK(pools_lock
);
37 * zpool_register_driver() - register a zpool implementation.
38 * @driver: driver to register
40 void zpool_register_driver(struct zpool_driver
*driver
)
42 spin_lock(&drivers_lock
);
43 atomic_set(&driver
->refcount
, 0);
44 list_add(&driver
->list
, &drivers_head
);
45 spin_unlock(&drivers_lock
);
47 EXPORT_SYMBOL(zpool_register_driver
);
50 * zpool_unregister_driver() - unregister a zpool implementation.
51 * @driver: driver to unregister.
53 * Module usage counting is used to prevent using a driver
54 * while/after unloading, so if this is called from module
55 * exit function, this should never fail; if called from
56 * other than the module exit function, and this returns
57 * failure, the driver is in use and must remain available.
59 int zpool_unregister_driver(struct zpool_driver
*driver
)
61 int ret
= 0, refcount
;
63 spin_lock(&drivers_lock
);
64 refcount
= atomic_read(&driver
->refcount
);
65 WARN_ON(refcount
< 0);
69 list_del(&driver
->list
);
70 spin_unlock(&drivers_lock
);
74 EXPORT_SYMBOL(zpool_unregister_driver
);
76 static struct zpool_driver
*zpool_get_driver(char *type
)
78 struct zpool_driver
*driver
;
80 spin_lock(&drivers_lock
);
81 list_for_each_entry(driver
, &drivers_head
, list
) {
82 if (!strcmp(driver
->type
, type
)) {
83 bool got
= try_module_get(driver
->owner
);
86 atomic_inc(&driver
->refcount
);
87 spin_unlock(&drivers_lock
);
88 return got
? driver
: NULL
;
92 spin_unlock(&drivers_lock
);
96 static void zpool_put_driver(struct zpool_driver
*driver
)
98 atomic_dec(&driver
->refcount
);
99 module_put(driver
->owner
);
103 * zpool_create_pool() - Create a new zpool
104 * @type The type of the zpool to create (e.g. zbud, zsmalloc)
105 * @name The name of the zpool (e.g. zram0, zswap)
106 * @gfp The GFP flags to use when allocating the pool.
107 * @ops The optional ops callback.
109 * This creates a new zpool of the specified type. The gfp flags will be
110 * used when allocating memory, if the implementation supports it. If the
111 * ops param is NULL, then the created zpool will not be shrinkable.
113 * Implementations must guarantee this to be thread-safe.
115 * Returns: New zpool on success, NULL on failure.
117 struct zpool
*zpool_create_pool(char *type
, char *name
, gfp_t gfp
,
118 struct zpool_ops
*ops
)
120 struct zpool_driver
*driver
;
123 pr_debug("creating pool type %s\n", type
);
125 driver
= zpool_get_driver(type
);
128 request_module("zpool-%s", type
);
129 driver
= zpool_get_driver(type
);
133 pr_err("no driver for type %s\n", type
);
137 zpool
= kmalloc(sizeof(*zpool
), gfp
);
139 pr_err("couldn't create zpool - out of memory\n");
140 zpool_put_driver(driver
);
144 zpool
->type
= driver
->type
;
145 zpool
->driver
= driver
;
146 zpool
->pool
= driver
->create(name
, gfp
, ops
, zpool
);
150 pr_err("couldn't create %s pool\n", type
);
151 zpool_put_driver(driver
);
156 pr_debug("created pool type %s\n", type
);
158 spin_lock(&pools_lock
);
159 list_add(&zpool
->list
, &pools_head
);
160 spin_unlock(&pools_lock
);
166 * zpool_destroy_pool() - Destroy a zpool
167 * @pool The zpool to destroy.
169 * Implementations must guarantee this to be thread-safe,
170 * however only when destroying different pools. The same
171 * pool should only be destroyed once, and should not be used
172 * after it is destroyed.
174 * This destroys an existing zpool. The zpool should not be in use.
176 void zpool_destroy_pool(struct zpool
*zpool
)
178 pr_debug("destroying pool type %s\n", zpool
->type
);
180 spin_lock(&pools_lock
);
181 list_del(&zpool
->list
);
182 spin_unlock(&pools_lock
);
183 zpool
->driver
->destroy(zpool
->pool
);
184 zpool_put_driver(zpool
->driver
);
189 * zpool_get_type() - Get the type of the zpool
190 * @pool The zpool to check
192 * This returns the type of the pool.
194 * Implementations must guarantee this to be thread-safe.
196 * Returns: The type of zpool.
198 char *zpool_get_type(struct zpool
*zpool
)
204 * zpool_malloc() - Allocate memory
205 * @pool The zpool to allocate from.
206 * @size The amount of memory to allocate.
207 * @gfp The GFP flags to use when allocating memory.
208 * @handle Pointer to the handle to set
210 * This allocates the requested amount of memory from the pool.
211 * The gfp flags will be used when allocating memory, if the
212 * implementation supports it. The provided @handle will be
213 * set to the allocated object handle.
215 * Implementations must guarantee this to be thread-safe.
217 * Returns: 0 on success, negative value on error.
219 int zpool_malloc(struct zpool
*zpool
, size_t size
, gfp_t gfp
,
220 unsigned long *handle
)
222 return zpool
->driver
->malloc(zpool
->pool
, size
, gfp
, handle
);
226 * zpool_free() - Free previously allocated memory
227 * @pool The zpool that allocated the memory.
228 * @handle The handle to the memory to free.
230 * This frees previously allocated memory. This does not guarantee
231 * that the pool will actually free memory, only that the memory
232 * in the pool will become available for use by the pool.
234 * Implementations must guarantee this to be thread-safe,
235 * however only when freeing different handles. The same
236 * handle should only be freed once, and should not be used
239 void zpool_free(struct zpool
*zpool
, unsigned long handle
)
241 zpool
->driver
->free(zpool
->pool
, handle
);
245 * zpool_shrink() - Shrink the pool size
246 * @pool The zpool to shrink.
247 * @pages The number of pages to shrink the pool.
248 * @reclaimed The number of pages successfully evicted.
250 * This attempts to shrink the actual memory size of the pool
251 * by evicting currently used handle(s). If the pool was
252 * created with no zpool_ops, or the evict call fails for any
253 * of the handles, this will fail. If non-NULL, the @reclaimed
254 * parameter will be set to the number of pages reclaimed,
255 * which may be more than the number of pages requested.
257 * Implementations must guarantee this to be thread-safe.
259 * Returns: 0 on success, negative value on error/failure.
261 int zpool_shrink(struct zpool
*zpool
, unsigned int pages
,
262 unsigned int *reclaimed
)
264 return zpool
->driver
->shrink(zpool
->pool
, pages
, reclaimed
);
268 * zpool_map_handle() - Map a previously allocated handle into memory
269 * @pool The zpool that the handle was allocated from
270 * @handle The handle to map
271 * @mm How the memory should be mapped
273 * This maps a previously allocated handle into memory. The @mm
274 * param indicates to the implementation how the memory will be
275 * used, i.e. read-only, write-only, read-write. If the
276 * implementation does not support it, the memory will be treated
279 * This may hold locks, disable interrupts, and/or preemption,
280 * and the zpool_unmap_handle() must be called to undo those
281 * actions. The code that uses the mapped handle should complete
282 * its operatons on the mapped handle memory quickly and unmap
283 * as soon as possible. As the implementation may use per-cpu
284 * data, multiple handles should not be mapped concurrently on
287 * Returns: A pointer to the handle's mapped memory area.
289 void *zpool_map_handle(struct zpool
*zpool
, unsigned long handle
,
290 enum zpool_mapmode mapmode
)
292 return zpool
->driver
->map(zpool
->pool
, handle
, mapmode
);
296 * zpool_unmap_handle() - Unmap a previously mapped handle
297 * @pool The zpool that the handle was allocated from
298 * @handle The handle to unmap
300 * This unmaps a previously mapped handle. Any locks or other
301 * actions that the implementation took in zpool_map_handle()
302 * will be undone here. The memory area returned from
303 * zpool_map_handle() should no longer be used after this.
305 void zpool_unmap_handle(struct zpool
*zpool
, unsigned long handle
)
307 zpool
->driver
->unmap(zpool
->pool
, handle
);
311 * zpool_get_total_size() - The total size of the pool
312 * @pool The zpool to check
314 * This returns the total size in bytes of the pool.
316 * Returns: Total size of the zpool in bytes.
318 u64
zpool_get_total_size(struct zpool
*zpool
)
320 return zpool
->driver
->total_size(zpool
->pool
);
323 static int __init
init_zpool(void)
329 static void __exit
exit_zpool(void)
331 pr_info("unloaded\n");
334 module_init(init_zpool
);
335 module_exit(exit_zpool
);
337 MODULE_LICENSE("GPL");
338 MODULE_AUTHOR("Dan Streetman <ddstreet@ieee.org>");
339 MODULE_DESCRIPTION("Common API for compressed memory storage");