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.
37  * zpool_register_driver() - register a zpool implementation.
43 	atomic_set(&driver->refcount, 0);  in zpool_register_driver()
44 	list_add(&driver->list, &drivers_head);  in zpool_register_driver()
50  * zpool_unregister_driver() - unregister a zpool implementation.
64 	refcount = atomic_read(&driver->refcount);  in zpool_unregister_driver()
67 		ret = -EBUSY;  in zpool_unregister_driver()
69 		list_del(&driver->list);  in zpool_unregister_driver()
76 /* this assumes @type is null-terminated. */
83 		if (!strcmp(driver->type, type)) {  in zpool_get_driver()
84 			bool got = try_module_get(driver->owner);  in zpool_get_driver()
87 				atomic_inc(&driver->refcount);  in zpool_get_driver()
99 	atomic_dec(&driver->refcount);  in zpool_put_driver()
100 	module_put(driver->owner);  in zpool_put_driver()
104  * zpool_has_pool() - Check if the pool driver is available
117  * The @type string must be null-terminated.
126 		request_module("zpool-%s", type);  in zpool_has_pool()
139  * zpool_create_pool() - Create a new zpool
146  * used when allocating memory, if the implementation supports it.  If the
149  * Implementations must guarantee this to be thread-safe.
151  * The @type and @name strings must be null-terminated.
166 		request_module("zpool-%s", type);  in zpool_create_pool()
177 		pr_err("couldn't create zpool - out of memory\n");  in zpool_create_pool()
182 	zpool->driver = driver;  in zpool_create_pool()
183 	zpool->pool = driver->create(name, gfp, ops, zpool);  in zpool_create_pool()
184 	zpool->ops = ops;  in zpool_create_pool()
185 	zpool->evictable = driver->shrink && ops && ops->evict;  in zpool_create_pool()
187 	if (!zpool->pool) {  in zpool_create_pool()
197 	list_add(&zpool->list, &pools_head);  in zpool_create_pool()
204  * zpool_destroy_pool() - Destroy a zpool
207  * Implementations must guarantee this to be thread-safe,
216 	pr_debug("destroying pool type %s\n", zpool->driver->type);  in zpool_destroy_pool()
219 	list_del(&zpool->list);  in zpool_destroy_pool()
221 	zpool->driver->destroy(zpool->pool);  in zpool_destroy_pool()
222 	zpool_put_driver(zpool->driver);  in zpool_destroy_pool()
227  * zpool_get_type() - Get the type of the zpool
232  * Implementations must guarantee this to be thread-safe.
238 	return zpool->driver->type;  in zpool_get_type()
242  * zpool_malloc_support_movable() - Check if the zpool supports
243  *	allocating movable memory
246  * This returns if the zpool supports allocating movable memory.
248  * Implementations must guarantee this to be thread-safe.
250  * Returns: true if the zpool supports allocating movable memory, false if not
254 	return zpool->driver->malloc_support_movable;  in zpool_malloc_support_movable()
258  * zpool_malloc() - Allocate memory
260  * @size:	The amount of memory to allocate.
261  * @gfp:	The GFP flags to use when allocating memory.
264  * This allocates the requested amount of memory from the pool.
265  * The gfp flags will be used when allocating memory, if the
269  * Implementations must guarantee this to be thread-safe.
276 	return zpool->driver->malloc(zpool->pool, size, gfp, handle);  in zpool_malloc()
280  * zpool_free() - Free previously allocated memory
281  * @zpool:	The zpool that allocated the memory.
282  * @handle:	The handle to the memory to free.
284  * This frees previously allocated memory.  This does not guarantee
285  * that the pool will actually free memory, only that the memory
288  * Implementations must guarantee this to be thread-safe,
295 	zpool->driver->free(zpool->pool, handle);  in zpool_free()
299  * zpool_shrink() - Shrink the pool size
304  * This attempts to shrink the actual memory size of the pool
307  * of the handles, this will fail.  If non-NULL, the @reclaimed
311  * Implementations must guarantee this to be thread-safe.
318 	return zpool->driver->shrink ?  in zpool_shrink()
319 	       zpool->driver->shrink(zpool->pool, pages, reclaimed) : -EINVAL;  in zpool_shrink()
323  * zpool_map_handle() - Map a previously allocated handle into memory
326  * @mapmode:	How the memory should be mapped
328  * This maps a previously allocated handle into memory.  The @mapmode
329  * param indicates to the implementation how the memory will be
330  * used, i.e. read-only, write-only, read-write.  If the
331  * implementation does not support it, the memory will be treated
332  * as read-write.
336  * actions.  The code that uses the mapped handle should complete
337  * its operatons on the mapped handle memory quickly and unmap
338  * as soon as possible.  As the implementation may use per-cpu
339  * data, multiple handles should not be mapped concurrently on
342  * Returns: A pointer to the handle's mapped memory area.
347 	return zpool->driver->map(zpool->pool, handle, mapmode);  in zpool_map_handle()
351  * zpool_unmap_handle() - Unmap a previously mapped handle
355  * This unmaps a previously mapped handle.  Any locks or other
357  * will be undone here.  The memory area returned from
362 	zpool->driver->unmap(zpool->pool, handle);  in zpool_unmap_handle()
366  * zpool_get_total_size() - The total size of the pool
375 	return zpool->driver->total_size(zpool->pool);  in zpool_get_total_size()
379  * zpool_evictable() - Test if zpool is potentially evictable
393 	return zpool->evictable;  in zpool_evictable()
398 MODULE_DESCRIPTION("Common API for compressed memory storage");