1 // SPDX-License-Identifier: GPL-2.0-only 1 // SPDX-License-Identifier: GPL-2.0-only
2 /* 2 /*
3 * zpool memory storage api 3 * zpool memory storage api
4 * 4 *
5 * Copyright (C) 2014 Dan Streetman 5 * Copyright (C) 2014 Dan Streetman
6 * 6 *
7 * This is a common frontend for memory storag 7 * This is a common frontend for memory storage pool implementations.
8 * Typically, this is used to store compressed 8 * Typically, this is used to store compressed memory.
9 */ 9 */
10 10
11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12 12
13 #include <linux/list.h> 13 #include <linux/list.h>
14 #include <linux/types.h> 14 #include <linux/types.h>
15 #include <linux/mm.h> 15 #include <linux/mm.h>
16 #include <linux/slab.h> 16 #include <linux/slab.h>
17 #include <linux/spinlock.h> 17 #include <linux/spinlock.h>
18 #include <linux/module.h> 18 #include <linux/module.h>
19 #include <linux/zpool.h> 19 #include <linux/zpool.h>
20 20
21 struct zpool { 21 struct zpool {
22 struct zpool_driver *driver; 22 struct zpool_driver *driver;
23 void *pool; 23 void *pool;
>> 24 const struct zpool_ops *ops;
>> 25 bool evictable;
>> 26
>> 27 struct list_head list;
24 }; 28 };
25 29
26 static LIST_HEAD(drivers_head); 30 static LIST_HEAD(drivers_head);
27 static DEFINE_SPINLOCK(drivers_lock); 31 static DEFINE_SPINLOCK(drivers_lock);
28 32
>> 33 static LIST_HEAD(pools_head);
>> 34 static DEFINE_SPINLOCK(pools_lock);
>> 35
29 /** 36 /**
30 * zpool_register_driver() - register a zpool 37 * zpool_register_driver() - register a zpool implementation.
31 * @driver: driver to register 38 * @driver: driver to register
32 */ 39 */
33 void zpool_register_driver(struct zpool_driver 40 void zpool_register_driver(struct zpool_driver *driver)
34 { 41 {
35 spin_lock(&drivers_lock); 42 spin_lock(&drivers_lock);
36 atomic_set(&driver->refcount, 0); 43 atomic_set(&driver->refcount, 0);
37 list_add(&driver->list, &drivers_head) 44 list_add(&driver->list, &drivers_head);
38 spin_unlock(&drivers_lock); 45 spin_unlock(&drivers_lock);
39 } 46 }
40 EXPORT_SYMBOL(zpool_register_driver); 47 EXPORT_SYMBOL(zpool_register_driver);
41 48
42 /** 49 /**
43 * zpool_unregister_driver() - unregister a zp 50 * zpool_unregister_driver() - unregister a zpool implementation.
44 * @driver: driver to unregister. 51 * @driver: driver to unregister.
45 * 52 *
46 * Module usage counting is used to prevent us 53 * Module usage counting is used to prevent using a driver
47 * while/after unloading, so if this is called 54 * while/after unloading, so if this is called from module
48 * exit function, this should never fail; if c 55 * exit function, this should never fail; if called from
49 * other than the module exit function, and th 56 * other than the module exit function, and this returns
50 * failure, the driver is in use and must rema 57 * failure, the driver is in use and must remain available.
51 */ 58 */
52 int zpool_unregister_driver(struct zpool_drive 59 int zpool_unregister_driver(struct zpool_driver *driver)
53 { 60 {
54 int ret = 0, refcount; 61 int ret = 0, refcount;
55 62
56 spin_lock(&drivers_lock); 63 spin_lock(&drivers_lock);
57 refcount = atomic_read(&driver->refcou 64 refcount = atomic_read(&driver->refcount);
58 WARN_ON(refcount < 0); 65 WARN_ON(refcount < 0);
59 if (refcount > 0) 66 if (refcount > 0)
60 ret = -EBUSY; 67 ret = -EBUSY;
61 else 68 else
62 list_del(&driver->list); 69 list_del(&driver->list);
63 spin_unlock(&drivers_lock); 70 spin_unlock(&drivers_lock);
64 71
65 return ret; 72 return ret;
66 } 73 }
67 EXPORT_SYMBOL(zpool_unregister_driver); 74 EXPORT_SYMBOL(zpool_unregister_driver);
68 75
69 /* this assumes @type is null-terminated. */ 76 /* this assumes @type is null-terminated. */
70 static struct zpool_driver *zpool_get_driver(c 77 static struct zpool_driver *zpool_get_driver(const char *type)
71 { 78 {
72 struct zpool_driver *driver; 79 struct zpool_driver *driver;
73 80
74 spin_lock(&drivers_lock); 81 spin_lock(&drivers_lock);
75 list_for_each_entry(driver, &drivers_h 82 list_for_each_entry(driver, &drivers_head, list) {
76 if (!strcmp(driver->type, type 83 if (!strcmp(driver->type, type)) {
77 bool got = try_module_ 84 bool got = try_module_get(driver->owner);
78 85
79 if (got) 86 if (got)
80 atomic_inc(&dr 87 atomic_inc(&driver->refcount);
81 spin_unlock(&drivers_l 88 spin_unlock(&drivers_lock);
82 return got ? driver : 89 return got ? driver : NULL;
83 } 90 }
84 } 91 }
85 92
86 spin_unlock(&drivers_lock); 93 spin_unlock(&drivers_lock);
87 return NULL; 94 return NULL;
88 } 95 }
89 96
90 static void zpool_put_driver(struct zpool_driv 97 static void zpool_put_driver(struct zpool_driver *driver)
91 { 98 {
92 atomic_dec(&driver->refcount); 99 atomic_dec(&driver->refcount);
93 module_put(driver->owner); 100 module_put(driver->owner);
94 } 101 }
95 102
96 /** 103 /**
97 * zpool_has_pool() - Check if the pool driver 104 * zpool_has_pool() - Check if the pool driver is available
98 * @type: The type of the zpool to check 105 * @type: The type of the zpool to check (e.g. zbud, zsmalloc)
99 * 106 *
100 * This checks if the @type pool driver is ava 107 * This checks if the @type pool driver is available. This will try to load
101 * the requested module, if needed, but there 108 * the requested module, if needed, but there is no guarantee the module will
102 * still be loaded and available immediately a 109 * still be loaded and available immediately after calling. If this returns
103 * true, the caller should assume the pool is 110 * true, the caller should assume the pool is available, but must be prepared
104 * to handle the @zpool_create_pool() returnin 111 * to handle the @zpool_create_pool() returning failure. However if this
105 * returns false, the caller should assume the 112 * returns false, the caller should assume the requested pool type is not
106 * available; either the requested pool type m 113 * available; either the requested pool type module does not exist, or could
107 * not be loaded, and calling @zpool_create_po 114 * not be loaded, and calling @zpool_create_pool() with the pool type will
108 * fail. 115 * fail.
109 * 116 *
110 * The @type string must be null-terminated. 117 * The @type string must be null-terminated.
111 * 118 *
112 * Returns: true if @type pool is available, f 119 * Returns: true if @type pool is available, false if not
113 */ 120 */
114 bool zpool_has_pool(char *type) 121 bool zpool_has_pool(char *type)
115 { 122 {
116 struct zpool_driver *driver = zpool_ge 123 struct zpool_driver *driver = zpool_get_driver(type);
117 124
118 if (!driver) { 125 if (!driver) {
119 request_module("zpool-%s", typ 126 request_module("zpool-%s", type);
120 driver = zpool_get_driver(type 127 driver = zpool_get_driver(type);
121 } 128 }
122 129
123 if (!driver) 130 if (!driver)
124 return false; 131 return false;
125 132
126 zpool_put_driver(driver); 133 zpool_put_driver(driver);
127 return true; 134 return true;
128 } 135 }
129 EXPORT_SYMBOL(zpool_has_pool); 136 EXPORT_SYMBOL(zpool_has_pool);
130 137
131 /** 138 /**
132 * zpool_create_pool() - Create a new zpool 139 * zpool_create_pool() - Create a new zpool
133 * @type: The type of the zpool to creat 140 * @type: The type of the zpool to create (e.g. zbud, zsmalloc)
134 * @name: The name of the zpool (e.g. zr 141 * @name: The name of the zpool (e.g. zram0, zswap)
135 * @gfp: The GFP flags to use when allo 142 * @gfp: The GFP flags to use when allocating the pool.
>> 143 * @ops: The optional ops callback.
136 * 144 *
137 * This creates a new zpool of the specified t 145 * This creates a new zpool of the specified type. The gfp flags will be
138 * used when allocating memory, if the impleme 146 * used when allocating memory, if the implementation supports it. If the
139 * ops param is NULL, then the created zpool w 147 * ops param is NULL, then the created zpool will not be evictable.
140 * 148 *
141 * Implementations must guarantee this to be t 149 * Implementations must guarantee this to be thread-safe.
142 * 150 *
143 * The @type and @name strings must be null-te 151 * The @type and @name strings must be null-terminated.
144 * 152 *
145 * Returns: New zpool on success, NULL on fail 153 * Returns: New zpool on success, NULL on failure.
146 */ 154 */
147 struct zpool *zpool_create_pool(const char *ty !! 155 struct zpool *zpool_create_pool(const char *type, const char *name, gfp_t gfp,
>> 156 const struct zpool_ops *ops)
148 { 157 {
149 struct zpool_driver *driver; 158 struct zpool_driver *driver;
150 struct zpool *zpool; 159 struct zpool *zpool;
151 160
152 pr_debug("creating pool type %s\n", ty 161 pr_debug("creating pool type %s\n", type);
153 162
154 driver = zpool_get_driver(type); 163 driver = zpool_get_driver(type);
155 164
156 if (!driver) { 165 if (!driver) {
157 request_module("zpool-%s", typ 166 request_module("zpool-%s", type);
158 driver = zpool_get_driver(type 167 driver = zpool_get_driver(type);
159 } 168 }
160 169
161 if (!driver) { 170 if (!driver) {
162 pr_err("no driver for type %s\ 171 pr_err("no driver for type %s\n", type);
163 return NULL; 172 return NULL;
164 } 173 }
165 174
166 zpool = kmalloc(sizeof(*zpool), gfp); 175 zpool = kmalloc(sizeof(*zpool), gfp);
167 if (!zpool) { 176 if (!zpool) {
168 pr_err("couldn't create zpool 177 pr_err("couldn't create zpool - out of memory\n");
169 zpool_put_driver(driver); 178 zpool_put_driver(driver);
170 return NULL; 179 return NULL;
171 } 180 }
172 181
173 zpool->driver = driver; 182 zpool->driver = driver;
174 zpool->pool = driver->create(name, gfp !! 183 zpool->pool = driver->create(name, gfp, ops, zpool);
>> 184 zpool->ops = ops;
>> 185 zpool->evictable = driver->shrink && ops && ops->evict;
175 186
176 if (!zpool->pool) { 187 if (!zpool->pool) {
177 pr_err("couldn't create %s poo 188 pr_err("couldn't create %s pool\n", type);
178 zpool_put_driver(driver); 189 zpool_put_driver(driver);
179 kfree(zpool); 190 kfree(zpool);
180 return NULL; 191 return NULL;
181 } 192 }
182 193
183 pr_debug("created pool type %s\n", typ 194 pr_debug("created pool type %s\n", type);
184 195
>> 196 spin_lock(&pools_lock);
>> 197 list_add(&zpool->list, &pools_head);
>> 198 spin_unlock(&pools_lock);
>> 199
185 return zpool; 200 return zpool;
186 } 201 }
187 202
188 /** 203 /**
189 * zpool_destroy_pool() - Destroy a zpool 204 * zpool_destroy_pool() - Destroy a zpool
190 * @zpool: The zpool to destroy. 205 * @zpool: The zpool to destroy.
191 * 206 *
192 * Implementations must guarantee this to be t 207 * Implementations must guarantee this to be thread-safe,
193 * however only when destroying different pool 208 * however only when destroying different pools. The same
194 * pool should only be destroyed once, and sho 209 * pool should only be destroyed once, and should not be used
195 * after it is destroyed. 210 * after it is destroyed.
196 * 211 *
197 * This destroys an existing zpool. The zpool 212 * This destroys an existing zpool. The zpool should not be in use.
198 */ 213 */
199 void zpool_destroy_pool(struct zpool *zpool) 214 void zpool_destroy_pool(struct zpool *zpool)
200 { 215 {
201 pr_debug("destroying pool type %s\n", 216 pr_debug("destroying pool type %s\n", zpool->driver->type);
202 217
>> 218 spin_lock(&pools_lock);
>> 219 list_del(&zpool->list);
>> 220 spin_unlock(&pools_lock);
203 zpool->driver->destroy(zpool->pool); 221 zpool->driver->destroy(zpool->pool);
204 zpool_put_driver(zpool->driver); 222 zpool_put_driver(zpool->driver);
205 kfree(zpool); 223 kfree(zpool);
206 } 224 }
207 225
208 /** 226 /**
209 * zpool_get_type() - Get the type of the zpoo 227 * zpool_get_type() - Get the type of the zpool
210 * @zpool: The zpool to check 228 * @zpool: The zpool to check
211 * 229 *
212 * This returns the type of the pool. 230 * This returns the type of the pool.
213 * 231 *
214 * Implementations must guarantee this to be t 232 * Implementations must guarantee this to be thread-safe.
215 * 233 *
216 * Returns: The type of zpool. 234 * Returns: The type of zpool.
217 */ 235 */
218 const char *zpool_get_type(struct zpool *zpool 236 const char *zpool_get_type(struct zpool *zpool)
219 { 237 {
220 return zpool->driver->type; 238 return zpool->driver->type;
221 } 239 }
222 240
223 /** 241 /**
224 * zpool_malloc_support_movable() - Check if t 242 * zpool_malloc_support_movable() - Check if the zpool supports
225 * allocating movable memory 243 * allocating movable memory
226 * @zpool: The zpool to check 244 * @zpool: The zpool to check
227 * 245 *
228 * This returns if the zpool supports allocati 246 * This returns if the zpool supports allocating movable memory.
229 * 247 *
230 * Implementations must guarantee this to be t 248 * Implementations must guarantee this to be thread-safe.
231 * 249 *
232 * Returns: true if the zpool supports allocat 250 * Returns: true if the zpool supports allocating movable memory, false if not
233 */ 251 */
234 bool zpool_malloc_support_movable(struct zpool 252 bool zpool_malloc_support_movable(struct zpool *zpool)
235 { 253 {
236 return zpool->driver->malloc_support_m 254 return zpool->driver->malloc_support_movable;
237 } 255 }
238 256
239 /** 257 /**
240 * zpool_malloc() - Allocate memory 258 * zpool_malloc() - Allocate memory
241 * @zpool: The zpool to allocate from. 259 * @zpool: The zpool to allocate from.
242 * @size: The amount of memory to alloca 260 * @size: The amount of memory to allocate.
243 * @gfp: The GFP flags to use when allo 261 * @gfp: The GFP flags to use when allocating memory.
244 * @handle: Pointer to the handle to set 262 * @handle: Pointer to the handle to set
245 * 263 *
246 * This allocates the requested amount of memo 264 * This allocates the requested amount of memory from the pool.
247 * The gfp flags will be used when allocating 265 * The gfp flags will be used when allocating memory, if the
248 * implementation supports it. The provided @ 266 * implementation supports it. The provided @handle will be
249 * set to the allocated object handle. 267 * set to the allocated object handle.
250 * 268 *
251 * Implementations must guarantee this to be t 269 * Implementations must guarantee this to be thread-safe.
252 * 270 *
253 * Returns: 0 on success, negative value on er 271 * Returns: 0 on success, negative value on error.
254 */ 272 */
255 int zpool_malloc(struct zpool *zpool, size_t s 273 int zpool_malloc(struct zpool *zpool, size_t size, gfp_t gfp,
256 unsigned long *handle) 274 unsigned long *handle)
257 { 275 {
258 return zpool->driver->malloc(zpool->po 276 return zpool->driver->malloc(zpool->pool, size, gfp, handle);
259 } 277 }
260 278
261 /** 279 /**
262 * zpool_free() - Free previously allocated me 280 * zpool_free() - Free previously allocated memory
263 * @zpool: The zpool that allocated the m 281 * @zpool: The zpool that allocated the memory.
264 * @handle: The handle to the memory to fr 282 * @handle: The handle to the memory to free.
265 * 283 *
266 * This frees previously allocated memory. Th 284 * This frees previously allocated memory. This does not guarantee
267 * that the pool will actually free memory, on 285 * that the pool will actually free memory, only that the memory
268 * in the pool will become available for use b 286 * in the pool will become available for use by the pool.
269 * 287 *
270 * Implementations must guarantee this to be t 288 * Implementations must guarantee this to be thread-safe,
271 * however only when freeing different handles 289 * however only when freeing different handles. The same
272 * handle should only be freed once, and shoul 290 * handle should only be freed once, and should not be used
273 * after freeing. 291 * after freeing.
274 */ 292 */
275 void zpool_free(struct zpool *zpool, unsigned 293 void zpool_free(struct zpool *zpool, unsigned long handle)
276 { 294 {
277 zpool->driver->free(zpool->pool, handl 295 zpool->driver->free(zpool->pool, handle);
278 } 296 }
279 297
280 /** 298 /**
>> 299 * zpool_shrink() - Shrink the pool size
>> 300 * @zpool: The zpool to shrink.
>> 301 * @pages: The number of pages to shrink the pool.
>> 302 * @reclaimed: The number of pages successfully evicted.
>> 303 *
>> 304 * This attempts to shrink the actual memory size of the pool
>> 305 * by evicting currently used handle(s). If the pool was
>> 306 * created with no zpool_ops, or the evict call fails for any
>> 307 * of the handles, this will fail. If non-NULL, the @reclaimed
>> 308 * parameter will be set to the number of pages reclaimed,
>> 309 * which may be more than the number of pages requested.
>> 310 *
>> 311 * Implementations must guarantee this to be thread-safe.
>> 312 *
>> 313 * Returns: 0 on success, negative value on error/failure.
>> 314 */
>> 315 int zpool_shrink(struct zpool *zpool, unsigned int pages,
>> 316 unsigned int *reclaimed)
>> 317 {
>> 318 return zpool->driver->shrink ?
>> 319 zpool->driver->shrink(zpool->pool, pages, reclaimed) : -EINVAL;
>> 320 }
>> 321
>> 322 /**
281 * zpool_map_handle() - Map a previously alloc 323 * zpool_map_handle() - Map a previously allocated handle into memory
282 * @zpool: The zpool that the handle was 324 * @zpool: The zpool that the handle was allocated from
283 * @handle: The handle to map 325 * @handle: The handle to map
284 * @mapmode: How the memory should be mappe 326 * @mapmode: How the memory should be mapped
285 * 327 *
286 * This maps a previously allocated handle int 328 * This maps a previously allocated handle into memory. The @mapmode
287 * param indicates to the implementation how t 329 * param indicates to the implementation how the memory will be
288 * used, i.e. read-only, write-only, read-writ 330 * used, i.e. read-only, write-only, read-write. If the
289 * implementation does not support it, the mem 331 * implementation does not support it, the memory will be treated
290 * as read-write. 332 * as read-write.
291 * 333 *
292 * This may hold locks, disable interrupts, an 334 * This may hold locks, disable interrupts, and/or preemption,
293 * and the zpool_unmap_handle() must be called 335 * and the zpool_unmap_handle() must be called to undo those
294 * actions. The code that uses the mapped han 336 * actions. The code that uses the mapped handle should complete
295 * its operations on the mapped handle memory !! 337 * its operatons on the mapped handle memory quickly and unmap
296 * as soon as possible. As the implementation 338 * as soon as possible. As the implementation may use per-cpu
297 * data, multiple handles should not be mapped 339 * data, multiple handles should not be mapped concurrently on
298 * any cpu. 340 * any cpu.
299 * 341 *
300 * Returns: A pointer to the handle's mapped m 342 * Returns: A pointer to the handle's mapped memory area.
301 */ 343 */
302 void *zpool_map_handle(struct zpool *zpool, un 344 void *zpool_map_handle(struct zpool *zpool, unsigned long handle,
303 enum zpool_mapmode map 345 enum zpool_mapmode mapmode)
304 { 346 {
305 return zpool->driver->map(zpool->pool, 347 return zpool->driver->map(zpool->pool, handle, mapmode);
306 } 348 }
307 349
308 /** 350 /**
309 * zpool_unmap_handle() - Unmap a previously m 351 * zpool_unmap_handle() - Unmap a previously mapped handle
310 * @zpool: The zpool that the handle was 352 * @zpool: The zpool that the handle was allocated from
311 * @handle: The handle to unmap 353 * @handle: The handle to unmap
312 * 354 *
313 * This unmaps a previously mapped handle. An 355 * This unmaps a previously mapped handle. Any locks or other
314 * actions that the implementation took in zpo 356 * actions that the implementation took in zpool_map_handle()
315 * will be undone here. The memory area retur 357 * will be undone here. The memory area returned from
316 * zpool_map_handle() should no longer be used 358 * zpool_map_handle() should no longer be used after this.
317 */ 359 */
318 void zpool_unmap_handle(struct zpool *zpool, u 360 void zpool_unmap_handle(struct zpool *zpool, unsigned long handle)
319 { 361 {
320 zpool->driver->unmap(zpool->pool, hand 362 zpool->driver->unmap(zpool->pool, handle);
321 } 363 }
322 364
323 /** 365 /**
324 * zpool_get_total_pages() - The total size of !! 366 * zpool_get_total_size() - The total size of the pool
325 * @zpool: The zpool to check 367 * @zpool: The zpool to check
326 * 368 *
327 * This returns the total size in pages of the !! 369 * This returns the total size in bytes of the pool.
328 * 370 *
329 * Returns: Total size of the zpool in pages. !! 371 * Returns: Total size of the zpool in bytes.
330 */ 372 */
331 u64 zpool_get_total_pages(struct zpool *zpool) !! 373 u64 zpool_get_total_size(struct zpool *zpool)
332 { 374 {
333 return zpool->driver->total_pages(zpoo !! 375 return zpool->driver->total_size(zpool->pool);
334 } 376 }
335 377
336 /** 378 /**
337 * zpool_can_sleep_mapped - Test if zpool can !! 379 * zpool_evictable() - Test if zpool is potentially evictable
338 * @zpool: The zpool to test 380 * @zpool: The zpool to test
339 * 381 *
340 * Some allocators enter non-preemptible conte !! 382 * Zpool is only potentially evictable when it's created with struct
341 * disable pagefaults) and exit that context i !! 383 * zpool_ops.evict and its driver implements struct zpool_driver.shrink.
342 * we can do with the mapped object. For insta !! 384 *
343 * asynchronous crypto API to decompress such !! 385 * However, it doesn't necessarily mean driver will use zpool_ops.evict
344 * since those will call into the scheduler. T !! 386 * in its implementation of zpool_driver.shrink. It could do internal
345 * we use such an allocator. !! 387 * defragmentation instead.
346 * 388 *
347 * Returns: true if zpool can sleep; false oth !! 389 * Returns: true if potentially evictable; false otherwise.
348 */ 390 */
349 bool zpool_can_sleep_mapped(struct zpool *zpoo !! 391 bool zpool_evictable(struct zpool *zpool)
350 { 392 {
351 return zpool->driver->sleep_mapped; !! 393 return zpool->evictable;
352 } 394 }
353 395
>> 396 MODULE_LICENSE("GPL");
354 MODULE_AUTHOR("Dan Streetman <ddstreet@ieee.or 397 MODULE_AUTHOR("Dan Streetman <ddstreet@ieee.org>");
355 MODULE_DESCRIPTION("Common API for compressed 398 MODULE_DESCRIPTION("Common API for compressed memory storage");
356 399
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