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 }; 24 };
25 25
26 static LIST_HEAD(drivers_head); 26 static LIST_HEAD(drivers_head);
27 static DEFINE_SPINLOCK(drivers_lock); 27 static DEFINE_SPINLOCK(drivers_lock);
28 28
29 /** 29 /**
30 * zpool_register_driver() - register a zpool 30 * zpool_register_driver() - register a zpool implementation.
31 * @driver: driver to register 31 * @driver: driver to register
32 */ 32 */
33 void zpool_register_driver(struct zpool_driver 33 void zpool_register_driver(struct zpool_driver *driver)
34 { 34 {
35 spin_lock(&drivers_lock); 35 spin_lock(&drivers_lock);
36 atomic_set(&driver->refcount, 0); 36 atomic_set(&driver->refcount, 0);
37 list_add(&driver->list, &drivers_head) 37 list_add(&driver->list, &drivers_head);
38 spin_unlock(&drivers_lock); 38 spin_unlock(&drivers_lock);
39 } 39 }
40 EXPORT_SYMBOL(zpool_register_driver); 40 EXPORT_SYMBOL(zpool_register_driver);
41 41
42 /** 42 /**
43 * zpool_unregister_driver() - unregister a zp 43 * zpool_unregister_driver() - unregister a zpool implementation.
44 * @driver: driver to unregister. 44 * @driver: driver to unregister.
45 * 45 *
46 * Module usage counting is used to prevent us 46 * Module usage counting is used to prevent using a driver
47 * while/after unloading, so if this is called 47 * while/after unloading, so if this is called from module
48 * exit function, this should never fail; if c 48 * exit function, this should never fail; if called from
49 * other than the module exit function, and th 49 * other than the module exit function, and this returns
50 * failure, the driver is in use and must rema 50 * failure, the driver is in use and must remain available.
51 */ 51 */
52 int zpool_unregister_driver(struct zpool_drive 52 int zpool_unregister_driver(struct zpool_driver *driver)
53 { 53 {
54 int ret = 0, refcount; 54 int ret = 0, refcount;
55 55
56 spin_lock(&drivers_lock); 56 spin_lock(&drivers_lock);
57 refcount = atomic_read(&driver->refcou 57 refcount = atomic_read(&driver->refcount);
58 WARN_ON(refcount < 0); 58 WARN_ON(refcount < 0);
59 if (refcount > 0) 59 if (refcount > 0)
60 ret = -EBUSY; 60 ret = -EBUSY;
61 else 61 else
62 list_del(&driver->list); 62 list_del(&driver->list);
63 spin_unlock(&drivers_lock); 63 spin_unlock(&drivers_lock);
64 64
65 return ret; 65 return ret;
66 } 66 }
67 EXPORT_SYMBOL(zpool_unregister_driver); 67 EXPORT_SYMBOL(zpool_unregister_driver);
68 68
69 /* this assumes @type is null-terminated. */ 69 /* this assumes @type is null-terminated. */
70 static struct zpool_driver *zpool_get_driver(c 70 static struct zpool_driver *zpool_get_driver(const char *type)
71 { 71 {
72 struct zpool_driver *driver; 72 struct zpool_driver *driver;
73 73
74 spin_lock(&drivers_lock); 74 spin_lock(&drivers_lock);
75 list_for_each_entry(driver, &drivers_h 75 list_for_each_entry(driver, &drivers_head, list) {
76 if (!strcmp(driver->type, type 76 if (!strcmp(driver->type, type)) {
77 bool got = try_module_ 77 bool got = try_module_get(driver->owner);
78 78
79 if (got) 79 if (got)
80 atomic_inc(&dr 80 atomic_inc(&driver->refcount);
81 spin_unlock(&drivers_l 81 spin_unlock(&drivers_lock);
82 return got ? driver : 82 return got ? driver : NULL;
83 } 83 }
84 } 84 }
85 85
86 spin_unlock(&drivers_lock); 86 spin_unlock(&drivers_lock);
87 return NULL; 87 return NULL;
88 } 88 }
89 89
90 static void zpool_put_driver(struct zpool_driv 90 static void zpool_put_driver(struct zpool_driver *driver)
91 { 91 {
92 atomic_dec(&driver->refcount); 92 atomic_dec(&driver->refcount);
93 module_put(driver->owner); 93 module_put(driver->owner);
94 } 94 }
95 95
96 /** 96 /**
97 * zpool_has_pool() - Check if the pool driver 97 * zpool_has_pool() - Check if the pool driver is available
98 * @type: The type of the zpool to check 98 * @type: The type of the zpool to check (e.g. zbud, zsmalloc)
99 * 99 *
100 * This checks if the @type pool driver is ava 100 * This checks if the @type pool driver is available. This will try to load
101 * the requested module, if needed, but there 101 * the requested module, if needed, but there is no guarantee the module will
102 * still be loaded and available immediately a 102 * still be loaded and available immediately after calling. If this returns
103 * true, the caller should assume the pool is 103 * true, the caller should assume the pool is available, but must be prepared
104 * to handle the @zpool_create_pool() returnin 104 * to handle the @zpool_create_pool() returning failure. However if this
105 * returns false, the caller should assume the 105 * returns false, the caller should assume the requested pool type is not
106 * available; either the requested pool type m 106 * available; either the requested pool type module does not exist, or could
107 * not be loaded, and calling @zpool_create_po 107 * not be loaded, and calling @zpool_create_pool() with the pool type will
108 * fail. 108 * fail.
109 * 109 *
110 * The @type string must be null-terminated. 110 * The @type string must be null-terminated.
111 * 111 *
112 * Returns: true if @type pool is available, f 112 * Returns: true if @type pool is available, false if not
113 */ 113 */
114 bool zpool_has_pool(char *type) 114 bool zpool_has_pool(char *type)
115 { 115 {
116 struct zpool_driver *driver = zpool_ge 116 struct zpool_driver *driver = zpool_get_driver(type);
117 117
118 if (!driver) { 118 if (!driver) {
119 request_module("zpool-%s", typ 119 request_module("zpool-%s", type);
120 driver = zpool_get_driver(type 120 driver = zpool_get_driver(type);
121 } 121 }
122 122
123 if (!driver) 123 if (!driver)
124 return false; 124 return false;
125 125
126 zpool_put_driver(driver); 126 zpool_put_driver(driver);
127 return true; 127 return true;
128 } 128 }
129 EXPORT_SYMBOL(zpool_has_pool); 129 EXPORT_SYMBOL(zpool_has_pool);
130 130
131 /** 131 /**
132 * zpool_create_pool() - Create a new zpool 132 * zpool_create_pool() - Create a new zpool
133 * @type: The type of the zpool to creat 133 * @type: The type of the zpool to create (e.g. zbud, zsmalloc)
134 * @name: The name of the zpool (e.g. zr 134 * @name: The name of the zpool (e.g. zram0, zswap)
135 * @gfp: The GFP flags to use when allo 135 * @gfp: The GFP flags to use when allocating the pool.
>> 136 * @ops: The optional ops callback.
136 * 137 *
137 * This creates a new zpool of the specified t 138 * This creates a new zpool of the specified type. The gfp flags will be
138 * used when allocating memory, if the impleme 139 * used when allocating memory, if the implementation supports it. If the
139 * ops param is NULL, then the created zpool w 140 * ops param is NULL, then the created zpool will not be evictable.
140 * 141 *
141 * Implementations must guarantee this to be t 142 * Implementations must guarantee this to be thread-safe.
142 * 143 *
143 * The @type and @name strings must be null-te 144 * The @type and @name strings must be null-terminated.
144 * 145 *
145 * Returns: New zpool on success, NULL on fail 146 * Returns: New zpool on success, NULL on failure.
146 */ 147 */
147 struct zpool *zpool_create_pool(const char *ty !! 148 struct zpool *zpool_create_pool(const char *type, const char *name, gfp_t gfp,
>> 149 const struct zpool_ops *ops)
148 { 150 {
149 struct zpool_driver *driver; 151 struct zpool_driver *driver;
150 struct zpool *zpool; 152 struct zpool *zpool;
151 153
152 pr_debug("creating pool type %s\n", ty 154 pr_debug("creating pool type %s\n", type);
153 155
154 driver = zpool_get_driver(type); 156 driver = zpool_get_driver(type);
155 157
156 if (!driver) { 158 if (!driver) {
157 request_module("zpool-%s", typ 159 request_module("zpool-%s", type);
158 driver = zpool_get_driver(type 160 driver = zpool_get_driver(type);
159 } 161 }
160 162
161 if (!driver) { 163 if (!driver) {
162 pr_err("no driver for type %s\ 164 pr_err("no driver for type %s\n", type);
163 return NULL; 165 return NULL;
164 } 166 }
165 167
166 zpool = kmalloc(sizeof(*zpool), gfp); 168 zpool = kmalloc(sizeof(*zpool), gfp);
167 if (!zpool) { 169 if (!zpool) {
168 pr_err("couldn't create zpool 170 pr_err("couldn't create zpool - out of memory\n");
169 zpool_put_driver(driver); 171 zpool_put_driver(driver);
170 return NULL; 172 return NULL;
171 } 173 }
172 174
173 zpool->driver = driver; 175 zpool->driver = driver;
174 zpool->pool = driver->create(name, gfp !! 176 zpool->pool = driver->create(name, gfp, ops, zpool);
175 177
176 if (!zpool->pool) { 178 if (!zpool->pool) {
177 pr_err("couldn't create %s poo 179 pr_err("couldn't create %s pool\n", type);
178 zpool_put_driver(driver); 180 zpool_put_driver(driver);
179 kfree(zpool); 181 kfree(zpool);
180 return NULL; 182 return NULL;
181 } 183 }
182 184
183 pr_debug("created pool type %s\n", typ 185 pr_debug("created pool type %s\n", type);
184 186
185 return zpool; 187 return zpool;
186 } 188 }
187 189
188 /** 190 /**
189 * zpool_destroy_pool() - Destroy a zpool 191 * zpool_destroy_pool() - Destroy a zpool
190 * @zpool: The zpool to destroy. 192 * @zpool: The zpool to destroy.
191 * 193 *
192 * Implementations must guarantee this to be t 194 * Implementations must guarantee this to be thread-safe,
193 * however only when destroying different pool 195 * however only when destroying different pools. The same
194 * pool should only be destroyed once, and sho 196 * pool should only be destroyed once, and should not be used
195 * after it is destroyed. 197 * after it is destroyed.
196 * 198 *
197 * This destroys an existing zpool. The zpool 199 * This destroys an existing zpool. The zpool should not be in use.
198 */ 200 */
199 void zpool_destroy_pool(struct zpool *zpool) 201 void zpool_destroy_pool(struct zpool *zpool)
200 { 202 {
201 pr_debug("destroying pool type %s\n", 203 pr_debug("destroying pool type %s\n", zpool->driver->type);
202 204
203 zpool->driver->destroy(zpool->pool); 205 zpool->driver->destroy(zpool->pool);
204 zpool_put_driver(zpool->driver); 206 zpool_put_driver(zpool->driver);
205 kfree(zpool); 207 kfree(zpool);
206 } 208 }
207 209
208 /** 210 /**
209 * zpool_get_type() - Get the type of the zpoo 211 * zpool_get_type() - Get the type of the zpool
210 * @zpool: The zpool to check 212 * @zpool: The zpool to check
211 * 213 *
212 * This returns the type of the pool. 214 * This returns the type of the pool.
213 * 215 *
214 * Implementations must guarantee this to be t 216 * Implementations must guarantee this to be thread-safe.
215 * 217 *
216 * Returns: The type of zpool. 218 * Returns: The type of zpool.
217 */ 219 */
218 const char *zpool_get_type(struct zpool *zpool 220 const char *zpool_get_type(struct zpool *zpool)
219 { 221 {
220 return zpool->driver->type; 222 return zpool->driver->type;
221 } 223 }
222 224
223 /** 225 /**
224 * zpool_malloc_support_movable() - Check if t 226 * zpool_malloc_support_movable() - Check if the zpool supports
225 * allocating movable memory 227 * allocating movable memory
226 * @zpool: The zpool to check 228 * @zpool: The zpool to check
227 * 229 *
228 * This returns if the zpool supports allocati 230 * This returns if the zpool supports allocating movable memory.
229 * 231 *
230 * Implementations must guarantee this to be t 232 * Implementations must guarantee this to be thread-safe.
231 * 233 *
232 * Returns: true if the zpool supports allocat 234 * Returns: true if the zpool supports allocating movable memory, false if not
233 */ 235 */
234 bool zpool_malloc_support_movable(struct zpool 236 bool zpool_malloc_support_movable(struct zpool *zpool)
235 { 237 {
236 return zpool->driver->malloc_support_m 238 return zpool->driver->malloc_support_movable;
237 } 239 }
238 240
239 /** 241 /**
240 * zpool_malloc() - Allocate memory 242 * zpool_malloc() - Allocate memory
241 * @zpool: The zpool to allocate from. 243 * @zpool: The zpool to allocate from.
242 * @size: The amount of memory to alloca 244 * @size: The amount of memory to allocate.
243 * @gfp: The GFP flags to use when allo 245 * @gfp: The GFP flags to use when allocating memory.
244 * @handle: Pointer to the handle to set 246 * @handle: Pointer to the handle to set
245 * 247 *
246 * This allocates the requested amount of memo 248 * This allocates the requested amount of memory from the pool.
247 * The gfp flags will be used when allocating 249 * The gfp flags will be used when allocating memory, if the
248 * implementation supports it. The provided @ 250 * implementation supports it. The provided @handle will be
249 * set to the allocated object handle. 251 * set to the allocated object handle.
250 * 252 *
251 * Implementations must guarantee this to be t 253 * Implementations must guarantee this to be thread-safe.
252 * 254 *
253 * Returns: 0 on success, negative value on er 255 * Returns: 0 on success, negative value on error.
254 */ 256 */
255 int zpool_malloc(struct zpool *zpool, size_t s 257 int zpool_malloc(struct zpool *zpool, size_t size, gfp_t gfp,
256 unsigned long *handle) 258 unsigned long *handle)
257 { 259 {
258 return zpool->driver->malloc(zpool->po 260 return zpool->driver->malloc(zpool->pool, size, gfp, handle);
259 } 261 }
260 262
261 /** 263 /**
262 * zpool_free() - Free previously allocated me 264 * zpool_free() - Free previously allocated memory
263 * @zpool: The zpool that allocated the m 265 * @zpool: The zpool that allocated the memory.
264 * @handle: The handle to the memory to fr 266 * @handle: The handle to the memory to free.
265 * 267 *
266 * This frees previously allocated memory. Th 268 * This frees previously allocated memory. This does not guarantee
267 * that the pool will actually free memory, on 269 * that the pool will actually free memory, only that the memory
268 * in the pool will become available for use b 270 * in the pool will become available for use by the pool.
269 * 271 *
270 * Implementations must guarantee this to be t 272 * Implementations must guarantee this to be thread-safe,
271 * however only when freeing different handles 273 * however only when freeing different handles. The same
272 * handle should only be freed once, and shoul 274 * handle should only be freed once, and should not be used
273 * after freeing. 275 * after freeing.
274 */ 276 */
275 void zpool_free(struct zpool *zpool, unsigned 277 void zpool_free(struct zpool *zpool, unsigned long handle)
276 { 278 {
277 zpool->driver->free(zpool->pool, handl 279 zpool->driver->free(zpool->pool, handle);
278 } 280 }
279 281
280 /** 282 /**
>> 283 * zpool_shrink() - Shrink the pool size
>> 284 * @zpool: The zpool to shrink.
>> 285 * @pages: The number of pages to shrink the pool.
>> 286 * @reclaimed: The number of pages successfully evicted.
>> 287 *
>> 288 * This attempts to shrink the actual memory size of the pool
>> 289 * by evicting currently used handle(s). If the pool was
>> 290 * created with no zpool_ops, or the evict call fails for any
>> 291 * of the handles, this will fail. If non-NULL, the @reclaimed
>> 292 * parameter will be set to the number of pages reclaimed,
>> 293 * which may be more than the number of pages requested.
>> 294 *
>> 295 * Implementations must guarantee this to be thread-safe.
>> 296 *
>> 297 * Returns: 0 on success, negative value on error/failure.
>> 298 */
>> 299 int zpool_shrink(struct zpool *zpool, unsigned int pages,
>> 300 unsigned int *reclaimed)
>> 301 {
>> 302 return zpool->driver->shrink ?
>> 303 zpool->driver->shrink(zpool->pool, pages, reclaimed) : -EINVAL;
>> 304 }
>> 305
>> 306 /**
281 * zpool_map_handle() - Map a previously alloc 307 * zpool_map_handle() - Map a previously allocated handle into memory
282 * @zpool: The zpool that the handle was 308 * @zpool: The zpool that the handle was allocated from
283 * @handle: The handle to map 309 * @handle: The handle to map
284 * @mapmode: How the memory should be mappe 310 * @mapmode: How the memory should be mapped
285 * 311 *
286 * This maps a previously allocated handle int 312 * This maps a previously allocated handle into memory. The @mapmode
287 * param indicates to the implementation how t 313 * param indicates to the implementation how the memory will be
288 * used, i.e. read-only, write-only, read-writ 314 * used, i.e. read-only, write-only, read-write. If the
289 * implementation does not support it, the mem 315 * implementation does not support it, the memory will be treated
290 * as read-write. 316 * as read-write.
291 * 317 *
292 * This may hold locks, disable interrupts, an 318 * This may hold locks, disable interrupts, and/or preemption,
293 * and the zpool_unmap_handle() must be called 319 * and the zpool_unmap_handle() must be called to undo those
294 * actions. The code that uses the mapped han 320 * actions. The code that uses the mapped handle should complete
295 * its operations on the mapped handle memory 321 * its operations on the mapped handle memory quickly and unmap
296 * as soon as possible. As the implementation 322 * as soon as possible. As the implementation may use per-cpu
297 * data, multiple handles should not be mapped 323 * data, multiple handles should not be mapped concurrently on
298 * any cpu. 324 * any cpu.
299 * 325 *
300 * Returns: A pointer to the handle's mapped m 326 * Returns: A pointer to the handle's mapped memory area.
301 */ 327 */
302 void *zpool_map_handle(struct zpool *zpool, un 328 void *zpool_map_handle(struct zpool *zpool, unsigned long handle,
303 enum zpool_mapmode map 329 enum zpool_mapmode mapmode)
304 { 330 {
305 return zpool->driver->map(zpool->pool, 331 return zpool->driver->map(zpool->pool, handle, mapmode);
306 } 332 }
307 333
308 /** 334 /**
309 * zpool_unmap_handle() - Unmap a previously m 335 * zpool_unmap_handle() - Unmap a previously mapped handle
310 * @zpool: The zpool that the handle was 336 * @zpool: The zpool that the handle was allocated from
311 * @handle: The handle to unmap 337 * @handle: The handle to unmap
312 * 338 *
313 * This unmaps a previously mapped handle. An 339 * This unmaps a previously mapped handle. Any locks or other
314 * actions that the implementation took in zpo 340 * actions that the implementation took in zpool_map_handle()
315 * will be undone here. The memory area retur 341 * will be undone here. The memory area returned from
316 * zpool_map_handle() should no longer be used 342 * zpool_map_handle() should no longer be used after this.
317 */ 343 */
318 void zpool_unmap_handle(struct zpool *zpool, u 344 void zpool_unmap_handle(struct zpool *zpool, unsigned long handle)
319 { 345 {
320 zpool->driver->unmap(zpool->pool, hand 346 zpool->driver->unmap(zpool->pool, handle);
321 } 347 }
322 348
323 /** 349 /**
324 * zpool_get_total_pages() - The total size of !! 350 * zpool_get_total_size() - The total size of the pool
325 * @zpool: The zpool to check 351 * @zpool: The zpool to check
326 * 352 *
327 * This returns the total size in pages of the !! 353 * This returns the total size in bytes of the pool.
>> 354 *
>> 355 * Returns: Total size of the zpool in bytes.
>> 356 */
>> 357 u64 zpool_get_total_size(struct zpool *zpool)
>> 358 {
>> 359 return zpool->driver->total_size(zpool->pool);
>> 360 }
>> 361
>> 362 /**
>> 363 * zpool_evictable() - Test if zpool is potentially evictable
>> 364 * @zpool: The zpool to test
>> 365 *
>> 366 * Zpool is only potentially evictable when it's created with struct
>> 367 * zpool_ops.evict and its driver implements struct zpool_driver.shrink.
>> 368 *
>> 369 * However, it doesn't necessarily mean driver will use zpool_ops.evict
>> 370 * in its implementation of zpool_driver.shrink. It could do internal
>> 371 * defragmentation instead.
328 * 372 *
329 * Returns: Total size of the zpool in pages. !! 373 * Returns: true if potentially evictable; false otherwise.
330 */ 374 */
331 u64 zpool_get_total_pages(struct zpool *zpool) !! 375 bool zpool_evictable(struct zpool *zpool)
332 { 376 {
333 return zpool->driver->total_pages(zpoo !! 377 return zpool->driver->shrink;
334 } 378 }
335 379
336 /** 380 /**
337 * zpool_can_sleep_mapped - Test if zpool can 381 * zpool_can_sleep_mapped - Test if zpool can sleep when do mapped.
338 * @zpool: The zpool to test 382 * @zpool: The zpool to test
339 * 383 *
340 * Some allocators enter non-preemptible conte 384 * Some allocators enter non-preemptible context in ->map() callback (e.g.
341 * disable pagefaults) and exit that context i 385 * disable pagefaults) and exit that context in ->unmap(), which limits what
342 * we can do with the mapped object. For insta 386 * we can do with the mapped object. For instance, we cannot wait for
343 * asynchronous crypto API to decompress such 387 * asynchronous crypto API to decompress such an object or take mutexes
344 * since those will call into the scheduler. T 388 * since those will call into the scheduler. This function tells us whether
345 * we use such an allocator. 389 * we use such an allocator.
346 * 390 *
347 * Returns: true if zpool can sleep; false oth 391 * Returns: true if zpool can sleep; false otherwise.
348 */ 392 */
349 bool zpool_can_sleep_mapped(struct zpool *zpoo 393 bool zpool_can_sleep_mapped(struct zpool *zpool)
350 { 394 {
351 return zpool->driver->sleep_mapped; 395 return zpool->driver->sleep_mapped;
352 } 396 }
353 397
354 MODULE_AUTHOR("Dan Streetman <ddstreet@ieee.or 398 MODULE_AUTHOR("Dan Streetman <ddstreet@ieee.org>");
355 MODULE_DESCRIPTION("Common API for compressed 399 MODULE_DESCRIPTION("Common API for compressed memory storage");
356 400
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