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.
33  * zpool_register_driver() - register a zpool implementation.
39 	atomic_set(&driver->refcount, 0);  in zpool_register_driver()
40 	list_add(&driver->list, &drivers_head);  in zpool_register_driver()
46  * zpool_unregister_driver() - unregister a zpool implementation.
60 	refcount = atomic_read(&driver->refcount);  in zpool_unregister_driver()
63 		ret = -EBUSY;  in zpool_unregister_driver()
65 		list_del(&driver->list);  in zpool_unregister_driver()
72 /* this assumes @type is null-terminated. */
79 		if (!strcmp(driver->type, type)) {  in zpool_get_driver()
80 			bool got = try_module_get(driver->owner);  in zpool_get_driver()
83 				atomic_inc(&driver->refcount);  in zpool_get_driver()
95 	atomic_dec(&driver->refcount);  in zpool_put_driver()
96 	module_put(driver->owner);  in zpool_put_driver()
100  * zpool_has_pool() - Check if the pool driver is available
113  * The @type string must be null-terminated.
122 		request_module("zpool-%s", type);  in zpool_has_pool()
135  * zpool_create_pool() - Create a new zpool
142  * used when allocating memory, if the implementation supports it.  If the
145  * Implementations must guarantee this to be thread-safe.
147  * The @type and @name strings must be null-terminated.
162 		request_module("zpool-%s", type);  in zpool_create_pool()
173 		pr_err("couldn't create zpool - out of memory\n");  in zpool_create_pool()
178 	zpool->driver = driver;  in zpool_create_pool()
179 	zpool->pool = driver->create(name, gfp, ops, zpool);  in zpool_create_pool()
180 	zpool->ops = ops;  in zpool_create_pool()
181 	zpool->evictable = driver->shrink && ops && ops->evict;  in zpool_create_pool()
182 	zpool->can_sleep_mapped = driver->sleep_mapped;  in zpool_create_pool()
184 	if (!zpool->pool) {  in zpool_create_pool()
197  * zpool_destroy_pool() - Destroy a zpool
200  * Implementations must guarantee this to be thread-safe,
209 	pr_debug("destroying pool type %s\n", zpool->driver->type);  in zpool_destroy_pool()
211 	zpool->driver->destroy(zpool->pool);  in zpool_destroy_pool()
212 	zpool_put_driver(zpool->driver);  in zpool_destroy_pool()
217  * zpool_get_type() - Get the type of the zpool
222  * Implementations must guarantee this to be thread-safe.
228 	return zpool->driver->type;  in zpool_get_type()
232  * zpool_malloc_support_movable() - Check if the zpool supports
233  *	allocating movable memory
236  * This returns if the zpool supports allocating movable memory.
238  * Implementations must guarantee this to be thread-safe.
240  * Returns: true if the zpool supports allocating movable memory, false if not
244 	return zpool->driver->malloc_support_movable;  in zpool_malloc_support_movable()
248  * zpool_malloc() - Allocate memory
250  * @size:	The amount of memory to allocate.
251  * @gfp:	The GFP flags to use when allocating memory.
254  * This allocates the requested amount of memory from the pool.
255  * The gfp flags will be used when allocating memory, if the
259  * Implementations must guarantee this to be thread-safe.
266 	return zpool->driver->malloc(zpool->pool, size, gfp, handle);  in zpool_malloc()
270  * zpool_free() - Free previously allocated memory
271  * @zpool:	The zpool that allocated the memory.
272  * @handle:	The handle to the memory to free.
274  * This frees previously allocated memory.  This does not guarantee
275  * that the pool will actually free memory, only that the memory
278  * Implementations must guarantee this to be thread-safe,
285 	zpool->driver->free(zpool->pool, handle);  in zpool_free()
289  * zpool_shrink() - Shrink the pool size
294  * This attempts to shrink the actual memory size of the pool
297  * of the handles, this will fail.  If non-NULL, the @reclaimed
301  * Implementations must guarantee this to be thread-safe.
308 	return zpool->driver->shrink ?  in zpool_shrink()
309 	       zpool->driver->shrink(zpool->pool, pages, reclaimed) : -EINVAL;  in zpool_shrink()
313  * zpool_map_handle() - Map a previously allocated handle into memory
316  * @mapmode:	How the memory should be mapped
318  * This maps a previously allocated handle into memory.  The @mapmode
319  * param indicates to the implementation how the memory will be
320  * used, i.e. read-only, write-only, read-write.  If the
321  * implementation does not support it, the memory will be treated
322  * as read-write.
326  * actions.  The code that uses the mapped handle should complete
327  * its operations on the mapped handle memory quickly and unmap
328  * as soon as possible.  As the implementation may use per-cpu
329  * data, multiple handles should not be mapped concurrently on
332  * Returns: A pointer to the handle's mapped memory area.
337 	return zpool->driver->map(zpool->pool, handle, mapmode);  in zpool_map_handle()
341  * zpool_unmap_handle() - Unmap a previously mapped handle
345  * This unmaps a previously mapped handle.  Any locks or other
347  * will be undone here.  The memory area returned from
352 	zpool->driver->unmap(zpool->pool, handle);  in zpool_unmap_handle()
356  * zpool_get_total_size() - The total size of the pool
365 	return zpool->driver->total_size(zpool->pool);  in zpool_get_total_size()
369  * zpool_evictable() - Test if zpool is potentially evictable
383 	return zpool->evictable;  in zpool_evictable()
387  * zpool_can_sleep_mapped - Test if zpool can sleep when do mapped.
394 	return zpool->can_sleep_mapped;  in zpool_can_sleep_mapped()
399 MODULE_DESCRIPTION("Common API for compressed memory storage");