]>
git.proxmox.com Git - mirror_ubuntu-bionic-kernel.git/blob - mm/zpool.c
2 * zpool memory storage api
4 * Copyright (C) 2014 Dan Streetman
6 * This is a common frontend for memory storage pool implementations.
7 * Typically, this is used to store compressed memory.
10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12 #include <linux/list.h>
13 #include <linux/types.h>
15 #include <linux/slab.h>
16 #include <linux/spinlock.h>
17 #include <linux/module.h>
18 #include <linux/zpool.h>
21 struct zpool_driver
*driver
;
23 const struct zpool_ops
*ops
;
25 struct list_head list
;
28 static LIST_HEAD(drivers_head
);
29 static DEFINE_SPINLOCK(drivers_lock
);
31 static LIST_HEAD(pools_head
);
32 static DEFINE_SPINLOCK(pools_lock
);
35 * zpool_register_driver() - register a zpool implementation.
36 * @driver: driver to register
38 void zpool_register_driver(struct zpool_driver
*driver
)
40 spin_lock(&drivers_lock
);
41 atomic_set(&driver
->refcount
, 0);
42 list_add(&driver
->list
, &drivers_head
);
43 spin_unlock(&drivers_lock
);
45 EXPORT_SYMBOL(zpool_register_driver
);
48 * zpool_unregister_driver() - unregister a zpool implementation.
49 * @driver: driver to unregister.
51 * Module usage counting is used to prevent using a driver
52 * while/after unloading, so if this is called from module
53 * exit function, this should never fail; if called from
54 * other than the module exit function, and this returns
55 * failure, the driver is in use and must remain available.
57 int zpool_unregister_driver(struct zpool_driver
*driver
)
59 int ret
= 0, refcount
;
61 spin_lock(&drivers_lock
);
62 refcount
= atomic_read(&driver
->refcount
);
63 WARN_ON(refcount
< 0);
67 list_del(&driver
->list
);
68 spin_unlock(&drivers_lock
);
72 EXPORT_SYMBOL(zpool_unregister_driver
);
74 /* this assumes @type is null-terminated. */
75 static struct zpool_driver
*zpool_get_driver(const char *type
)
77 struct zpool_driver
*driver
;
79 spin_lock(&drivers_lock
);
80 list_for_each_entry(driver
, &drivers_head
, list
) {
81 if (!strcmp(driver
->type
, type
)) {
82 bool got
= try_module_get(driver
->owner
);
85 atomic_inc(&driver
->refcount
);
86 spin_unlock(&drivers_lock
);
87 return got
? driver
: NULL
;
91 spin_unlock(&drivers_lock
);
95 static void zpool_put_driver(struct zpool_driver
*driver
)
97 atomic_dec(&driver
->refcount
);
98 module_put(driver
->owner
);
102 * zpool_has_pool() - Check if the pool driver is available
103 * @type The type of the zpool to check (e.g. zbud, zsmalloc)
105 * This checks if the @type pool driver is available. This will try to load
106 * the requested module, if needed, but there is no guarantee the module will
107 * still be loaded and available immediately after calling. If this returns
108 * true, the caller should assume the pool is available, but must be prepared
109 * to handle the @zpool_create_pool() returning failure. However if this
110 * returns false, the caller should assume the requested pool type is not
111 * available; either the requested pool type module does not exist, or could
112 * not be loaded, and calling @zpool_create_pool() with the pool type will
115 * The @type string must be null-terminated.
117 * Returns: true if @type pool is available, false if not
119 bool zpool_has_pool(char *type
)
121 struct zpool_driver
*driver
= zpool_get_driver(type
);
124 request_module("zpool-%s", type
);
125 driver
= zpool_get_driver(type
);
131 zpool_put_driver(driver
);
134 EXPORT_SYMBOL(zpool_has_pool
);
137 * zpool_create_pool() - Create a new zpool
138 * @type The type of the zpool to create (e.g. zbud, zsmalloc)
139 * @name The name of the zpool (e.g. zram0, zswap)
140 * @gfp The GFP flags to use when allocating the pool.
141 * @ops The optional ops callback.
143 * This creates a new zpool of the specified type. The gfp flags will be
144 * used when allocating memory, if the implementation supports it. If the
145 * ops param is NULL, then the created zpool will not be shrinkable.
147 * Implementations must guarantee this to be thread-safe.
149 * The @type and @name strings must be null-terminated.
151 * Returns: New zpool on success, NULL on failure.
153 struct zpool
*zpool_create_pool(const char *type
, const char *name
, gfp_t gfp
,
154 const struct zpool_ops
*ops
)
156 struct zpool_driver
*driver
;
159 pr_debug("creating pool type %s\n", type
);
161 driver
= zpool_get_driver(type
);
164 request_module("zpool-%s", type
);
165 driver
= zpool_get_driver(type
);
169 pr_err("no driver for type %s\n", type
);
173 zpool
= kmalloc(sizeof(*zpool
), gfp
);
175 pr_err("couldn't create zpool - out of memory\n");
176 zpool_put_driver(driver
);
180 zpool
->driver
= driver
;
181 zpool
->pool
= driver
->create(name
, gfp
, ops
, zpool
);
185 pr_err("couldn't create %s pool\n", type
);
186 zpool_put_driver(driver
);
191 pr_debug("created pool type %s\n", type
);
193 spin_lock(&pools_lock
);
194 list_add(&zpool
->list
, &pools_head
);
195 spin_unlock(&pools_lock
);
201 * zpool_destroy_pool() - Destroy a zpool
202 * @pool The zpool to destroy.
204 * Implementations must guarantee this to be thread-safe,
205 * however only when destroying different pools. The same
206 * pool should only be destroyed once, and should not be used
207 * after it is destroyed.
209 * This destroys an existing zpool. The zpool should not be in use.
211 void zpool_destroy_pool(struct zpool
*zpool
)
213 pr_debug("destroying pool type %s\n", zpool
->driver
->type
);
215 spin_lock(&pools_lock
);
216 list_del(&zpool
->list
);
217 spin_unlock(&pools_lock
);
218 zpool
->driver
->destroy(zpool
->pool
);
219 zpool_put_driver(zpool
->driver
);
224 * zpool_get_type() - Get the type of the zpool
225 * @pool The zpool to check
227 * This returns the type of the pool.
229 * Implementations must guarantee this to be thread-safe.
231 * Returns: The type of zpool.
233 const char *zpool_get_type(struct zpool
*zpool
)
235 return zpool
->driver
->type
;
239 * zpool_malloc() - Allocate memory
240 * @pool The zpool to allocate from.
241 * @size The amount of memory to allocate.
242 * @gfp The GFP flags to use when allocating memory.
243 * @handle Pointer to the handle to set
245 * This allocates the requested amount of memory from the pool.
246 * The gfp flags will be used when allocating memory, if the
247 * implementation supports it. The provided @handle will be
248 * set to the allocated object handle.
250 * Implementations must guarantee this to be thread-safe.
252 * Returns: 0 on success, negative value on error.
254 int zpool_malloc(struct zpool
*zpool
, size_t size
, gfp_t gfp
,
255 unsigned long *handle
)
257 return zpool
->driver
->malloc(zpool
->pool
, size
, gfp
, handle
);
261 * zpool_free() - Free previously allocated memory
262 * @pool The zpool that allocated the memory.
263 * @handle The handle to the memory to free.
265 * This frees previously allocated memory. This does not guarantee
266 * that the pool will actually free memory, only that the memory
267 * in the pool will become available for use by the pool.
269 * Implementations must guarantee this to be thread-safe,
270 * however only when freeing different handles. The same
271 * handle should only be freed once, and should not be used
274 void zpool_free(struct zpool
*zpool
, unsigned long handle
)
276 zpool
->driver
->free(zpool
->pool
, handle
);
280 * zpool_shrink() - Shrink the pool size
281 * @pool The zpool to shrink.
282 * @pages The number of pages to shrink the pool.
283 * @reclaimed The number of pages successfully evicted.
285 * This attempts to shrink the actual memory size of the pool
286 * by evicting currently used handle(s). If the pool was
287 * created with no zpool_ops, or the evict call fails for any
288 * of the handles, this will fail. If non-NULL, the @reclaimed
289 * parameter will be set to the number of pages reclaimed,
290 * which may be more than the number of pages requested.
292 * Implementations must guarantee this to be thread-safe.
294 * Returns: 0 on success, negative value on error/failure.
296 int zpool_shrink(struct zpool
*zpool
, unsigned int pages
,
297 unsigned int *reclaimed
)
299 return zpool
->driver
->shrink(zpool
->pool
, pages
, reclaimed
);
303 * zpool_map_handle() - Map a previously allocated handle into memory
304 * @pool The zpool that the handle was allocated from
305 * @handle The handle to map
306 * @mm How the memory should be mapped
308 * This maps a previously allocated handle into memory. The @mm
309 * param indicates to the implementation how the memory will be
310 * used, i.e. read-only, write-only, read-write. If the
311 * implementation does not support it, the memory will be treated
314 * This may hold locks, disable interrupts, and/or preemption,
315 * and the zpool_unmap_handle() must be called to undo those
316 * actions. The code that uses the mapped handle should complete
317 * its operatons on the mapped handle memory quickly and unmap
318 * as soon as possible. As the implementation may use per-cpu
319 * data, multiple handles should not be mapped concurrently on
322 * Returns: A pointer to the handle's mapped memory area.
324 void *zpool_map_handle(struct zpool
*zpool
, unsigned long handle
,
325 enum zpool_mapmode mapmode
)
327 return zpool
->driver
->map(zpool
->pool
, handle
, mapmode
);
331 * zpool_unmap_handle() - Unmap a previously mapped handle
332 * @pool The zpool that the handle was allocated from
333 * @handle The handle to unmap
335 * This unmaps a previously mapped handle. Any locks or other
336 * actions that the implementation took in zpool_map_handle()
337 * will be undone here. The memory area returned from
338 * zpool_map_handle() should no longer be used after this.
340 void zpool_unmap_handle(struct zpool
*zpool
, unsigned long handle
)
342 zpool
->driver
->unmap(zpool
->pool
, handle
);
346 * zpool_get_total_size() - The total size of the pool
347 * @pool The zpool to check
349 * This returns the total size in bytes of the pool.
351 * Returns: Total size of the zpool in bytes.
353 u64
zpool_get_total_size(struct zpool
*zpool
)
355 return zpool
->driver
->total_size(zpool
->pool
);
358 MODULE_LICENSE("GPL");
359 MODULE_AUTHOR("Dan Streetman <ddstreet@ieee.org>");
360 MODULE_DESCRIPTION("Common API for compressed memory storage");