2  * zpool memory storage api
6  * This is a common frontend for memory storage pool implementations.
7  * Typically, this is used to store compressed memory.
36  * zpool_register_driver() - register a zpool implementation.
42 	atomic_set(&driver->refcount, 0);  in zpool_register_driver()
43 	list_add(&driver->list, &drivers_head);  in zpool_register_driver()
49  * zpool_unregister_driver() - unregister a zpool implementation.
63 	refcount = atomic_read(&driver->refcount);  in zpool_unregister_driver()
66 		ret = -EBUSY;  in zpool_unregister_driver()
68 		list_del(&driver->list);  in zpool_unregister_driver()
75 /* this assumes @type is null-terminated. */
82 		if (!strcmp(driver->type, type)) {  in zpool_get_driver()
83 			bool got = try_module_get(driver->owner);  in zpool_get_driver()
86 				atomic_inc(&driver->refcount);  in zpool_get_driver()
98 	atomic_dec(&driver->refcount);  in zpool_put_driver()
99 	module_put(driver->owner);  in zpool_put_driver()
103  * zpool_has_pool() - Check if the pool driver is available
116  * The @type string must be null-terminated.
125 		request_module("zpool-%s", type);  in zpool_has_pool()
138  * zpool_create_pool() - Create a new zpool
145  * used when allocating memory, if the implementation supports it.  If the
148  * Implementations must guarantee this to be thread-safe.
150  * The @type and @name strings must be null-terminated.
165 		request_module("zpool-%s", type);  in zpool_create_pool()
176 		pr_err("couldn't create zpool - out of memory\n");  in zpool_create_pool()
181 	zpool->driver = driver;  in zpool_create_pool()
182 	zpool->pool = driver->create(name, gfp, ops, zpool);  in zpool_create_pool()
183 	zpool->ops = ops;  in zpool_create_pool()
184 	zpool->evictable = driver->shrink && ops && ops->evict;  in zpool_create_pool()
186 	if (!zpool->pool) {  in zpool_create_pool()
196 	list_add(&zpool->list, &pools_head);  in zpool_create_pool()
203  * zpool_destroy_pool() - Destroy a zpool
206  * Implementations must guarantee this to be thread-safe,
215 	pr_debug("destroying pool type %s\n", zpool->driver->type);  in zpool_destroy_pool()
218 	list_del(&zpool->list);  in zpool_destroy_pool()
220 	zpool->driver->destroy(zpool->pool);  in zpool_destroy_pool()
221 	zpool_put_driver(zpool->driver);  in zpool_destroy_pool()
226  * zpool_get_type() - Get the type of the zpool
231  * Implementations must guarantee this to be thread-safe.
237 	return zpool->driver->type;  in zpool_get_type()
241  * zpool_malloc() - Allocate memory
243  * @size:	The amount of memory to allocate.
244  * @gfp:	The GFP flags to use when allocating memory.
247  * This allocates the requested amount of memory from the pool.
248  * The gfp flags will be used when allocating memory, if the
252  * Implementations must guarantee this to be thread-safe.
259 	return zpool->driver->malloc(zpool->pool, size, gfp, handle);  in zpool_malloc()
263  * zpool_free() - Free previously allocated memory
264  * @zpool:	The zpool that allocated the memory.
265  * @handle:	The handle to the memory to free.
267  * This frees previously allocated memory.  This does not guarantee
268  * that the pool will actually free memory, only that the memory
271  * Implementations must guarantee this to be thread-safe,
278 	zpool->driver->free(zpool->pool, handle);  in zpool_free()
282  * zpool_shrink() - Shrink the pool size
287  * This attempts to shrink the actual memory size of the pool
290  * of the handles, this will fail.  If non-NULL, the @reclaimed
294  * Implementations must guarantee this to be thread-safe.
301 	return zpool->driver->shrink ?  in zpool_shrink()
302 	       zpool->driver->shrink(zpool->pool, pages, reclaimed) : -EINVAL;  in zpool_shrink()
306  * zpool_map_handle() - Map a previously allocated handle into memory
309  * @mapmode:	How the memory should be mapped
311  * This maps a previously allocated handle into memory.  The @mapmode
312  * param indicates to the implementation how the memory will be
313  * used, i.e. read-only, write-only, read-write.  If the
314  * implementation does not support it, the memory will be treated
315  * as read-write.
319  * actions.  The code that uses the mapped handle should complete
320  * its operatons on the mapped handle memory quickly and unmap
321  * as soon as possible.  As the implementation may use per-cpu
322  * data, multiple handles should not be mapped concurrently on
325  * Returns: A pointer to the handle's mapped memory area.
330 	return zpool->driver->map(zpool->pool, handle, mapmode);  in zpool_map_handle()
334  * zpool_unmap_handle() - Unmap a previously mapped handle
338  * This unmaps a previously mapped handle.  Any locks or other
340  * will be undone here.  The memory area returned from
345 	zpool->driver->unmap(zpool->pool, handle);  in zpool_unmap_handle()
349  * zpool_get_total_size() - The total size of the pool
358 	return zpool->driver->total_size(zpool->pool);  in zpool_get_total_size()
362  * zpool_evictable() - Test if zpool is potentially evictable
376 	return zpool->evictable;  in zpool_evictable()
381 MODULE_DESCRIPTION("Common API for compressed memory storage");