]>
git.proxmox.com Git - mirror_ubuntu-kernels.git/blob - mm/zpool.c
1 // SPDX-License-Identifier: GPL-2.0-only
3 * zpool memory storage api
5 * Copyright (C) 2014 Dan Streetman
7 * This is a common frontend for memory storage pool implementations.
8 * Typically, this is used to store compressed memory.
11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13 #include <linux/list.h>
14 #include <linux/types.h>
16 #include <linux/slab.h>
17 #include <linux/spinlock.h>
18 #include <linux/module.h>
19 #include <linux/zpool.h>
22 struct zpool_driver
*driver
;
24 const struct zpool_ops
*ops
;
26 bool can_sleep_mapped
;
29 static LIST_HEAD(drivers_head
);
30 static DEFINE_SPINLOCK(drivers_lock
);
33 * zpool_register_driver() - register a zpool implementation.
34 * @driver: driver to register
36 void zpool_register_driver(struct zpool_driver
*driver
)
38 spin_lock(&drivers_lock
);
39 atomic_set(&driver
->refcount
, 0);
40 list_add(&driver
->list
, &drivers_head
);
41 spin_unlock(&drivers_lock
);
43 EXPORT_SYMBOL(zpool_register_driver
);
46 * zpool_unregister_driver() - unregister a zpool implementation.
47 * @driver: driver to unregister.
49 * Module usage counting is used to prevent using a driver
50 * while/after unloading, so if this is called from module
51 * exit function, this should never fail; if called from
52 * other than the module exit function, and this returns
53 * failure, the driver is in use and must remain available.
55 int zpool_unregister_driver(struct zpool_driver
*driver
)
57 int ret
= 0, refcount
;
59 spin_lock(&drivers_lock
);
60 refcount
= atomic_read(&driver
->refcount
);
61 WARN_ON(refcount
< 0);
65 list_del(&driver
->list
);
66 spin_unlock(&drivers_lock
);
70 EXPORT_SYMBOL(zpool_unregister_driver
);
72 /* this assumes @type is null-terminated. */
73 static struct zpool_driver
*zpool_get_driver(const char *type
)
75 struct zpool_driver
*driver
;
77 spin_lock(&drivers_lock
);
78 list_for_each_entry(driver
, &drivers_head
, list
) {
79 if (!strcmp(driver
->type
, type
)) {
80 bool got
= try_module_get(driver
->owner
);
83 atomic_inc(&driver
->refcount
);
84 spin_unlock(&drivers_lock
);
85 return got
? driver
: NULL
;
89 spin_unlock(&drivers_lock
);
93 static void zpool_put_driver(struct zpool_driver
*driver
)
95 atomic_dec(&driver
->refcount
);
96 module_put(driver
->owner
);
100 * zpool_has_pool() - Check if the pool driver is available
101 * @type: The type of the zpool to check (e.g. zbud, zsmalloc)
103 * This checks if the @type pool driver is available. This will try to load
104 * the requested module, if needed, but there is no guarantee the module will
105 * still be loaded and available immediately after calling. If this returns
106 * true, the caller should assume the pool is available, but must be prepared
107 * to handle the @zpool_create_pool() returning failure. However if this
108 * returns false, the caller should assume the requested pool type is not
109 * available; either the requested pool type module does not exist, or could
110 * not be loaded, and calling @zpool_create_pool() with the pool type will
113 * The @type string must be null-terminated.
115 * Returns: true if @type pool is available, false if not
117 bool zpool_has_pool(char *type
)
119 struct zpool_driver
*driver
= zpool_get_driver(type
);
122 request_module("zpool-%s", type
);
123 driver
= zpool_get_driver(type
);
129 zpool_put_driver(driver
);
132 EXPORT_SYMBOL(zpool_has_pool
);
135 * zpool_create_pool() - Create a new zpool
136 * @type: The type of the zpool to create (e.g. zbud, zsmalloc)
137 * @name: The name of the zpool (e.g. zram0, zswap)
138 * @gfp: The GFP flags to use when allocating the pool.
139 * @ops: The optional ops callback.
141 * This creates a new zpool of the specified type. The gfp flags will be
142 * used when allocating memory, if the implementation supports it. If the
143 * ops param is NULL, then the created zpool will not be evictable.
145 * Implementations must guarantee this to be thread-safe.
147 * The @type and @name strings must be null-terminated.
149 * Returns: New zpool on success, NULL on failure.
151 struct zpool
*zpool_create_pool(const char *type
, const char *name
, gfp_t gfp
,
152 const struct zpool_ops
*ops
)
154 struct zpool_driver
*driver
;
157 pr_debug("creating pool type %s\n", type
);
159 driver
= zpool_get_driver(type
);
162 request_module("zpool-%s", type
);
163 driver
= zpool_get_driver(type
);
167 pr_err("no driver for type %s\n", type
);
171 zpool
= kmalloc(sizeof(*zpool
), gfp
);
173 pr_err("couldn't create zpool - out of memory\n");
174 zpool_put_driver(driver
);
178 zpool
->driver
= driver
;
179 zpool
->pool
= driver
->create(name
, gfp
, ops
, zpool
);
181 zpool
->evictable
= driver
->shrink
&& ops
&& ops
->evict
;
182 zpool
->can_sleep_mapped
= driver
->sleep_mapped
;
185 pr_err("couldn't create %s pool\n", type
);
186 zpool_put_driver(driver
);
191 pr_debug("created pool type %s\n", type
);
197 * zpool_destroy_pool() - Destroy a zpool
198 * @zpool: The zpool to destroy.
200 * Implementations must guarantee this to be thread-safe,
201 * however only when destroying different pools. The same
202 * pool should only be destroyed once, and should not be used
203 * after it is destroyed.
205 * This destroys an existing zpool. The zpool should not be in use.
207 void zpool_destroy_pool(struct zpool
*zpool
)
209 pr_debug("destroying pool type %s\n", zpool
->driver
->type
);
211 zpool
->driver
->destroy(zpool
->pool
);
212 zpool_put_driver(zpool
->driver
);
217 * zpool_get_type() - Get the type of the zpool
218 * @zpool: The zpool to check
220 * This returns the type of the pool.
222 * Implementations must guarantee this to be thread-safe.
224 * Returns: The type of zpool.
226 const char *zpool_get_type(struct zpool
*zpool
)
228 return zpool
->driver
->type
;
232 * zpool_malloc_support_movable() - Check if the zpool supports
233 * allocating movable memory
234 * @zpool: The zpool to check
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
242 bool zpool_malloc_support_movable(struct zpool
*zpool
)
244 return zpool
->driver
->malloc_support_movable
;
248 * zpool_malloc() - Allocate memory
249 * @zpool: The zpool to allocate from.
250 * @size: The amount of memory to allocate.
251 * @gfp: The GFP flags to use when allocating memory.
252 * @handle: Pointer to the handle to set
254 * This allocates the requested amount of memory from the pool.
255 * The gfp flags will be used when allocating memory, if the
256 * implementation supports it. The provided @handle will be
257 * set to the allocated object handle.
259 * Implementations must guarantee this to be thread-safe.
261 * Returns: 0 on success, negative value on error.
263 int zpool_malloc(struct zpool
*zpool
, size_t size
, gfp_t gfp
,
264 unsigned long *handle
)
266 return zpool
->driver
->malloc(zpool
->pool
, size
, gfp
, handle
);
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
276 * in the pool will become available for use by the pool.
278 * Implementations must guarantee this to be thread-safe,
279 * however only when freeing different handles. The same
280 * handle should only be freed once, and should not be used
283 void zpool_free(struct zpool
*zpool
, unsigned long handle
)
285 zpool
->driver
->free(zpool
->pool
, handle
);
289 * zpool_shrink() - Shrink the pool size
290 * @zpool: The zpool to shrink.
291 * @pages: The number of pages to shrink the pool.
292 * @reclaimed: The number of pages successfully evicted.
294 * This attempts to shrink the actual memory size of the pool
295 * by evicting currently used handle(s). If the pool was
296 * created with no zpool_ops, or the evict call fails for any
297 * of the handles, this will fail. If non-NULL, the @reclaimed
298 * parameter will be set to the number of pages reclaimed,
299 * which may be more than the number of pages requested.
301 * Implementations must guarantee this to be thread-safe.
303 * Returns: 0 on success, negative value on error/failure.
305 int zpool_shrink(struct zpool
*zpool
, unsigned int pages
,
306 unsigned int *reclaimed
)
308 return zpool
->driver
->shrink
?
309 zpool
->driver
->shrink(zpool
->pool
, pages
, reclaimed
) : -EINVAL
;
313 * zpool_map_handle() - Map a previously allocated handle into memory
314 * @zpool: The zpool that the handle was allocated from
315 * @handle: The handle to map
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
324 * This may hold locks, disable interrupts, and/or preemption,
325 * and the zpool_unmap_handle() must be called to undo those
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.
334 void *zpool_map_handle(struct zpool
*zpool
, unsigned long handle
,
335 enum zpool_mapmode mapmode
)
337 return zpool
->driver
->map(zpool
->pool
, handle
, mapmode
);
341 * zpool_unmap_handle() - Unmap a previously mapped handle
342 * @zpool: The zpool that the handle was allocated from
343 * @handle: The handle to unmap
345 * This unmaps a previously mapped handle. Any locks or other
346 * actions that the implementation took in zpool_map_handle()
347 * will be undone here. The memory area returned from
348 * zpool_map_handle() should no longer be used after this.
350 void zpool_unmap_handle(struct zpool
*zpool
, unsigned long handle
)
352 zpool
->driver
->unmap(zpool
->pool
, handle
);
356 * zpool_get_total_size() - The total size of the pool
357 * @zpool: The zpool to check
359 * This returns the total size in bytes of the pool.
361 * Returns: Total size of the zpool in bytes.
363 u64
zpool_get_total_size(struct zpool
*zpool
)
365 return zpool
->driver
->total_size(zpool
->pool
);
369 * zpool_evictable() - Test if zpool is potentially evictable
370 * @zpool: The zpool to test
372 * Zpool is only potentially evictable when it's created with struct
373 * zpool_ops.evict and its driver implements struct zpool_driver.shrink.
375 * However, it doesn't necessarily mean driver will use zpool_ops.evict
376 * in its implementation of zpool_driver.shrink. It could do internal
377 * defragmentation instead.
379 * Returns: true if potentially evictable; false otherwise.
381 bool zpool_evictable(struct zpool
*zpool
)
383 return zpool
->evictable
;
387 * zpool_can_sleep_mapped - Test if zpool can sleep when do mapped.
388 * @zpool: The zpool to test
390 * Returns: true if zpool can sleep; false otherwise.
392 bool zpool_can_sleep_mapped(struct zpool
*zpool
)
394 return zpool
->can_sleep_mapped
;
397 MODULE_LICENSE("GPL");
398 MODULE_AUTHOR("Dan Streetman <ddstreet@ieee.org>");
399 MODULE_DESCRIPTION("Common API for compressed memory storage");