1 // SPDX-License-Identifier: GPL-2.0-only
3  * zpool memory storage api
7  * This is a common frontend for memory storage pool implementations.
8  * Typically, this is used to store compressed memory.
30  * zpool_register_driver() - register a zpool implementation.
36 	atomic_set(&driver->refcount, 0);  in zpool_register_driver()
37 	list_add(&driver->list, &drivers_head);  in zpool_register_driver()
43  * zpool_unregister_driver() - unregister a zpool implementation.
57 	refcount = atomic_read(&driver->refcount);  in zpool_unregister_driver()
60 		ret = -EBUSY;  in zpool_unregister_driver()
62 		list_del(&driver->list);  in zpool_unregister_driver()
69 /* this assumes @type is null-terminated. */
76 		if (!strcmp(driver->type, type)) {  in zpool_get_driver()
77 			bool got = try_module_get(driver->owner);  in zpool_get_driver()
80 				atomic_inc(&driver->refcount);  in zpool_get_driver()
92 	atomic_dec(&driver->refcount);  in zpool_put_driver()
93 	module_put(driver->owner);  in zpool_put_driver()
97  * zpool_has_pool() - Check if the pool driver is available
110  * The @type string must be null-terminated.
119 		request_module("zpool-%s", type);  in zpool_has_pool()
132  * zpool_create_pool() - Create a new zpool
138  * used when allocating memory, if the implementation supports it.  If the
141  * Implementations must guarantee this to be thread-safe.
143  * The @type and @name strings must be null-terminated.
157 		request_module("zpool-%s", type);  in zpool_create_pool()
168 		pr_err("couldn't create zpool - out of memory\n");  in zpool_create_pool()
173 	zpool->driver = driver;  in zpool_create_pool()
174 	zpool->pool = driver->create(name, gfp);  in zpool_create_pool()
176 	if (!zpool->pool) {  in zpool_create_pool()
189  * zpool_destroy_pool() - Destroy a zpool
192  * Implementations must guarantee this to be thread-safe,
201 	pr_debug("destroying pool type %s\n", zpool->driver->type);  in zpool_destroy_pool()
203 	zpool->driver->destroy(zpool->pool);  in zpool_destroy_pool()
204 	zpool_put_driver(zpool->driver);  in zpool_destroy_pool()
209  * zpool_get_type() - Get the type of the zpool
214  * Implementations must guarantee this to be thread-safe.
220 	return zpool->driver->type;  in zpool_get_type()
224  * zpool_malloc_support_movable() - Check if the zpool supports
225  *	allocating movable memory
228  * This returns if the zpool supports allocating movable memory.
230  * Implementations must guarantee this to be thread-safe.
232  * Returns: true if the zpool supports allocating movable memory, false if not
236 	return zpool->driver->malloc_support_movable;  in zpool_malloc_support_movable()
240  * zpool_malloc() - Allocate memory
242  * @size:	The amount of memory to allocate.
243  * @gfp:	The GFP flags to use when allocating memory.
246  * This allocates the requested amount of memory from the pool.
247  * The gfp flags will be used when allocating memory, if the
251  * Implementations must guarantee this to be thread-safe.
258 	return zpool->driver->malloc(zpool->pool, size, gfp, handle);  in zpool_malloc()
262  * zpool_free() - Free previously allocated memory
263  * @zpool:	The zpool that allocated the memory.
264  * @handle:	The handle to the memory to free.
266  * This frees previously allocated memory.  This does not guarantee
267  * that the pool will actually free memory, only that the memory
270  * Implementations must guarantee this to be thread-safe,
277 	zpool->driver->free(zpool->pool, handle);  in zpool_free()
281  * zpool_map_handle() - Map a previously allocated handle into memory
284  * @mapmode:	How the memory should be mapped
286  * This maps a previously allocated handle into memory.  The @mapmode
287  * param indicates to the implementation how the memory will be
288  * used, i.e. read-only, write-only, read-write.  If the
289  * implementation does not support it, the memory will be treated
290  * as read-write.
294  * actions.  The code that uses the mapped handle should complete
295  * its operations on the mapped handle memory quickly and unmap
296  * as soon as possible.  As the implementation may use per-cpu
297  * data, multiple handles should not be mapped concurrently on
300  * Returns: A pointer to the handle's mapped memory area.
305 	return zpool->driver->map(zpool->pool, handle, mapmode);  in zpool_map_handle()
309  * zpool_unmap_handle() - Unmap a previously mapped handle
313  * This unmaps a previously mapped handle.  Any locks or other
315  * will be undone here.  The memory area returned from
320 	zpool->driver->unmap(zpool->pool, handle);  in zpool_unmap_handle()
324  * zpool_get_total_size() - The total size of the pool
333 	return zpool->driver->total_size(zpool->pool);  in zpool_get_total_size()
337  * zpool_can_sleep_mapped - Test if zpool can sleep when do mapped.
340  * Some allocators enter non-preemptible context in ->map() callback (e.g.
341  * disable pagefaults) and exit that context in ->unmap(), which limits what
342  * we can do with the mapped object. For instance, we cannot wait for
351 	return zpool->driver->sleep_mapped;  in zpool_can_sleep_mapped()
355 MODULE_DESCRIPTION("Common API for compressed memory storage");