1 | /* |
2 | * zswap.c - zswap driver file |
3 | * |
4 | * zswap is a backend for frontswap that takes pages that are in the process |
5 | * of being swapped out and attempts to compress and store them in a |
6 | * RAM-based memory pool. This can result in a significant I/O reduction on |
7 | * the swap device and, in the case where decompressing from RAM is faster |
8 | * than reading from the swap device, can also improve workload performance. |
9 | * |
10 | * Copyright (C) 2012 Seth Jennings <sjenning@linux.vnet.ibm.com> |
11 | * |
12 | * This program is free software; you can redistribute it and/or |
13 | * modify it under the terms of the GNU General Public License |
14 | * as published by the Free Software Foundation; either version 2 |
15 | * of the License, or (at your option) any later version. |
16 | * |
17 | * This program is distributed in the hope that it will be useful, |
18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
20 | * GNU General Public License for more details. |
21 | */ |
22 | |
23 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
24 | |
25 | #include <linux/module.h> |
26 | #include <linux/cpu.h> |
27 | #include <linux/highmem.h> |
28 | #include <linux/slab.h> |
29 | #include <linux/spinlock.h> |
30 | #include <linux/types.h> |
31 | #include <linux/atomic.h> |
32 | #include <linux/frontswap.h> |
33 | #include <linux/rbtree.h> |
34 | #include <linux/swap.h> |
35 | #include <linux/crypto.h> |
36 | #include <linux/mempool.h> |
37 | #include <linux/zpool.h> |
38 | |
39 | #include <linux/mm_types.h> |
40 | #include <linux/page-flags.h> |
41 | #include <linux/swapops.h> |
42 | #include <linux/writeback.h> |
43 | #include <linux/pagemap.h> |
44 | |
45 | /********************************* |
46 | * statistics |
47 | **********************************/ |
48 | /* Total bytes used by the compressed storage */ |
49 | static u64 zswap_pool_total_size; |
50 | /* The number of compressed pages currently stored in zswap */ |
51 | static atomic_t zswap_stored_pages = ATOMIC_INIT(0); |
52 | /* The number of same-value filled pages currently stored in zswap */ |
53 | static atomic_t zswap_same_filled_pages = ATOMIC_INIT(0); |
54 | |
55 | /* |
56 | * The statistics below are not protected from concurrent access for |
57 | * performance reasons so they may not be a 100% accurate. However, |
58 | * they do provide useful information on roughly how many times a |
59 | * certain event is occurring. |
60 | */ |
61 | |
62 | /* Pool limit was hit (see zswap_max_pool_percent) */ |
63 | static u64 zswap_pool_limit_hit; |
64 | /* Pages written back when pool limit was reached */ |
65 | static u64 zswap_written_back_pages; |
66 | /* Store failed due to a reclaim failure after pool limit was reached */ |
67 | static u64 zswap_reject_reclaim_fail; |
68 | /* Compressed page was too big for the allocator to (optimally) store */ |
69 | static u64 zswap_reject_compress_poor; |
70 | /* Store failed because underlying allocator could not get memory */ |
71 | static u64 zswap_reject_alloc_fail; |
72 | /* Store failed because the entry metadata could not be allocated (rare) */ |
73 | static u64 zswap_reject_kmemcache_fail; |
74 | /* Duplicate store was encountered (rare) */ |
75 | static u64 zswap_duplicate_entry; |
76 | |
77 | /********************************* |
78 | * tunables |
79 | **********************************/ |
80 | |
81 | #define ZSWAP_PARAM_UNSET "" |
82 | |
83 | /* Enable/disable zswap (disabled by default) */ |
84 | static bool zswap_enabled; |
85 | static int zswap_enabled_param_set(const char *, |
86 | const struct kernel_param *); |
87 | static struct kernel_param_ops zswap_enabled_param_ops = { |
88 | .set = zswap_enabled_param_set, |
89 | .get = param_get_bool, |
90 | }; |
91 | module_param_cb(enabled, &zswap_enabled_param_ops, &zswap_enabled, 0644); |
92 | |
93 | /* Crypto compressor to use */ |
94 | #define ZSWAP_COMPRESSOR_DEFAULT "lzo" |
95 | static char *zswap_compressor = ZSWAP_COMPRESSOR_DEFAULT; |
96 | static int zswap_compressor_param_set(const char *, |
97 | const struct kernel_param *); |
98 | static struct kernel_param_ops zswap_compressor_param_ops = { |
99 | .set = zswap_compressor_param_set, |
100 | .get = param_get_charp, |
101 | .free = param_free_charp, |
102 | }; |
103 | module_param_cb(compressor, &zswap_compressor_param_ops, |
104 | &zswap_compressor, 0644); |
105 | |
106 | /* Compressed storage zpool to use */ |
107 | #define ZSWAP_ZPOOL_DEFAULT "zbud" |
108 | static char *zswap_zpool_type = ZSWAP_ZPOOL_DEFAULT; |
109 | static int zswap_zpool_param_set(const char *, const struct kernel_param *); |
110 | static struct kernel_param_ops zswap_zpool_param_ops = { |
111 | .set = zswap_zpool_param_set, |
112 | .get = param_get_charp, |
113 | .free = param_free_charp, |
114 | }; |
115 | module_param_cb(zpool, &zswap_zpool_param_ops, &zswap_zpool_type, 0644); |
116 | |
117 | /* The maximum percentage of memory that the compressed pool can occupy */ |
118 | static unsigned int zswap_max_pool_percent = 20; |
119 | module_param_named(max_pool_percent, zswap_max_pool_percent, uint, 0644); |
120 | |
121 | /* Enable/disable handling same-value filled pages (enabled by default) */ |
122 | static bool zswap_same_filled_pages_enabled = true; |
123 | module_param_named(same_filled_pages_enabled, zswap_same_filled_pages_enabled, |
124 | bool, 0644); |
125 | |
126 | /********************************* |
127 | * data structures |
128 | **********************************/ |
129 | |
130 | struct zswap_pool { |
131 | struct zpool *zpool; |
132 | struct crypto_comp * __percpu *tfm; |
133 | struct kref kref; |
134 | struct list_head list; |
135 | struct work_struct work; |
136 | struct hlist_node node; |
137 | char tfm_name[CRYPTO_MAX_ALG_NAME]; |
138 | }; |
139 | |
140 | /* |
141 | * struct zswap_entry |
142 | * |
143 | * This structure contains the metadata for tracking a single compressed |
144 | * page within zswap. |
145 | * |
146 | * rbnode - links the entry into red-black tree for the appropriate swap type |
147 | * offset - the swap offset for the entry. Index into the red-black tree. |
148 | * refcount - the number of outstanding reference to the entry. This is needed |
149 | * to protect against premature freeing of the entry by code |
150 | * concurrent calls to load, invalidate, and writeback. The lock |
151 | * for the zswap_tree structure that contains the entry must |
152 | * be held while changing the refcount. Since the lock must |
153 | * be held, there is no reason to also make refcount atomic. |
154 | * length - the length in bytes of the compressed page data. Needed during |
155 | * decompression. For a same value filled page length is 0. |
156 | * pool - the zswap_pool the entry's data is in |
157 | * handle - zpool allocation handle that stores the compressed page data |
158 | * value - value of the same-value filled pages which have same content |
159 | */ |
160 | struct zswap_entry { |
161 | struct rb_node rbnode; |
162 | pgoff_t offset; |
163 | int refcount; |
164 | unsigned int length; |
165 | struct zswap_pool *pool; |
166 | union { |
167 | unsigned long handle; |
168 | unsigned long value; |
169 | }; |
170 | }; |
171 | |
172 | struct { |
173 | swp_entry_t ; |
174 | }; |
175 | |
176 | /* |
177 | * The tree lock in the zswap_tree struct protects a few things: |
178 | * - the rbtree |
179 | * - the refcount field of each entry in the tree |
180 | */ |
181 | struct zswap_tree { |
182 | struct rb_root rbroot; |
183 | spinlock_t lock; |
184 | }; |
185 | |
186 | static struct zswap_tree *zswap_trees[MAX_SWAPFILES]; |
187 | |
188 | /* RCU-protected iteration */ |
189 | static LIST_HEAD(zswap_pools); |
190 | /* protects zswap_pools list modification */ |
191 | static DEFINE_SPINLOCK(zswap_pools_lock); |
192 | /* pool counter to provide unique names to zpool */ |
193 | static atomic_t zswap_pools_count = ATOMIC_INIT(0); |
194 | |
195 | /* used by param callback function */ |
196 | static bool zswap_init_started; |
197 | |
198 | /* fatal error during init */ |
199 | static bool zswap_init_failed; |
200 | |
201 | /* init completed, but couldn't create the initial pool */ |
202 | static bool zswap_has_pool; |
203 | |
204 | /********************************* |
205 | * helpers and fwd declarations |
206 | **********************************/ |
207 | |
208 | #define zswap_pool_debug(msg, p) \ |
209 | pr_debug("%s pool %s/%s\n", msg, (p)->tfm_name, \ |
210 | zpool_get_type((p)->zpool)) |
211 | |
212 | static int zswap_writeback_entry(struct zpool *pool, unsigned long handle); |
213 | static int zswap_pool_get(struct zswap_pool *pool); |
214 | static void zswap_pool_put(struct zswap_pool *pool); |
215 | |
216 | static const struct zpool_ops zswap_zpool_ops = { |
217 | .evict = zswap_writeback_entry |
218 | }; |
219 | |
220 | static bool zswap_is_full(void) |
221 | { |
222 | return totalram_pages() * zswap_max_pool_percent / 100 < |
223 | DIV_ROUND_UP(zswap_pool_total_size, PAGE_SIZE); |
224 | } |
225 | |
226 | static void zswap_update_total_size(void) |
227 | { |
228 | struct zswap_pool *pool; |
229 | u64 total = 0; |
230 | |
231 | rcu_read_lock(); |
232 | |
233 | list_for_each_entry_rcu(pool, &zswap_pools, list) |
234 | total += zpool_get_total_size(pool->zpool); |
235 | |
236 | rcu_read_unlock(); |
237 | |
238 | zswap_pool_total_size = total; |
239 | } |
240 | |
241 | /********************************* |
242 | * zswap entry functions |
243 | **********************************/ |
244 | static struct kmem_cache *zswap_entry_cache; |
245 | |
246 | static int __init zswap_entry_cache_create(void) |
247 | { |
248 | zswap_entry_cache = KMEM_CACHE(zswap_entry, 0); |
249 | return zswap_entry_cache == NULL; |
250 | } |
251 | |
252 | static void __init zswap_entry_cache_destroy(void) |
253 | { |
254 | kmem_cache_destroy(zswap_entry_cache); |
255 | } |
256 | |
257 | static struct zswap_entry *zswap_entry_cache_alloc(gfp_t gfp) |
258 | { |
259 | struct zswap_entry *entry; |
260 | entry = kmem_cache_alloc(zswap_entry_cache, gfp); |
261 | if (!entry) |
262 | return NULL; |
263 | entry->refcount = 1; |
264 | RB_CLEAR_NODE(&entry->rbnode); |
265 | return entry; |
266 | } |
267 | |
268 | static void zswap_entry_cache_free(struct zswap_entry *entry) |
269 | { |
270 | kmem_cache_free(zswap_entry_cache, entry); |
271 | } |
272 | |
273 | /********************************* |
274 | * rbtree functions |
275 | **********************************/ |
276 | static struct zswap_entry *zswap_rb_search(struct rb_root *root, pgoff_t offset) |
277 | { |
278 | struct rb_node *node = root->rb_node; |
279 | struct zswap_entry *entry; |
280 | |
281 | while (node) { |
282 | entry = rb_entry(node, struct zswap_entry, rbnode); |
283 | if (entry->offset > offset) |
284 | node = node->rb_left; |
285 | else if (entry->offset < offset) |
286 | node = node->rb_right; |
287 | else |
288 | return entry; |
289 | } |
290 | return NULL; |
291 | } |
292 | |
293 | /* |
294 | * In the case that a entry with the same offset is found, a pointer to |
295 | * the existing entry is stored in dupentry and the function returns -EEXIST |
296 | */ |
297 | static int zswap_rb_insert(struct rb_root *root, struct zswap_entry *entry, |
298 | struct zswap_entry **dupentry) |
299 | { |
300 | struct rb_node **link = &root->rb_node, *parent = NULL; |
301 | struct zswap_entry *myentry; |
302 | |
303 | while (*link) { |
304 | parent = *link; |
305 | myentry = rb_entry(parent, struct zswap_entry, rbnode); |
306 | if (myentry->offset > entry->offset) |
307 | link = &(*link)->rb_left; |
308 | else if (myentry->offset < entry->offset) |
309 | link = &(*link)->rb_right; |
310 | else { |
311 | *dupentry = myentry; |
312 | return -EEXIST; |
313 | } |
314 | } |
315 | rb_link_node(&entry->rbnode, parent, link); |
316 | rb_insert_color(&entry->rbnode, root); |
317 | return 0; |
318 | } |
319 | |
320 | static void zswap_rb_erase(struct rb_root *root, struct zswap_entry *entry) |
321 | { |
322 | if (!RB_EMPTY_NODE(&entry->rbnode)) { |
323 | rb_erase(&entry->rbnode, root); |
324 | RB_CLEAR_NODE(&entry->rbnode); |
325 | } |
326 | } |
327 | |
328 | /* |
329 | * Carries out the common pattern of freeing and entry's zpool allocation, |
330 | * freeing the entry itself, and decrementing the number of stored pages. |
331 | */ |
332 | static void zswap_free_entry(struct zswap_entry *entry) |
333 | { |
334 | if (!entry->length) |
335 | atomic_dec(&zswap_same_filled_pages); |
336 | else { |
337 | zpool_free(entry->pool->zpool, entry->handle); |
338 | zswap_pool_put(entry->pool); |
339 | } |
340 | zswap_entry_cache_free(entry); |
341 | atomic_dec(&zswap_stored_pages); |
342 | zswap_update_total_size(); |
343 | } |
344 | |
345 | /* caller must hold the tree lock */ |
346 | static void zswap_entry_get(struct zswap_entry *entry) |
347 | { |
348 | entry->refcount++; |
349 | } |
350 | |
351 | /* caller must hold the tree lock |
352 | * remove from the tree and free it, if nobody reference the entry |
353 | */ |
354 | static void zswap_entry_put(struct zswap_tree *tree, |
355 | struct zswap_entry *entry) |
356 | { |
357 | int refcount = --entry->refcount; |
358 | |
359 | BUG_ON(refcount < 0); |
360 | if (refcount == 0) { |
361 | zswap_rb_erase(&tree->rbroot, entry); |
362 | zswap_free_entry(entry); |
363 | } |
364 | } |
365 | |
366 | /* caller must hold the tree lock */ |
367 | static struct zswap_entry *zswap_entry_find_get(struct rb_root *root, |
368 | pgoff_t offset) |
369 | { |
370 | struct zswap_entry *entry; |
371 | |
372 | entry = zswap_rb_search(root, offset); |
373 | if (entry) |
374 | zswap_entry_get(entry); |
375 | |
376 | return entry; |
377 | } |
378 | |
379 | /********************************* |
380 | * per-cpu code |
381 | **********************************/ |
382 | static DEFINE_PER_CPU(u8 *, zswap_dstmem); |
383 | |
384 | static int zswap_dstmem_prepare(unsigned int cpu) |
385 | { |
386 | u8 *dst; |
387 | |
388 | dst = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu)); |
389 | if (!dst) |
390 | return -ENOMEM; |
391 | |
392 | per_cpu(zswap_dstmem, cpu) = dst; |
393 | return 0; |
394 | } |
395 | |
396 | static int zswap_dstmem_dead(unsigned int cpu) |
397 | { |
398 | u8 *dst; |
399 | |
400 | dst = per_cpu(zswap_dstmem, cpu); |
401 | kfree(dst); |
402 | per_cpu(zswap_dstmem, cpu) = NULL; |
403 | |
404 | return 0; |
405 | } |
406 | |
407 | static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node) |
408 | { |
409 | struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node); |
410 | struct crypto_comp *tfm; |
411 | |
412 | if (WARN_ON(*per_cpu_ptr(pool->tfm, cpu))) |
413 | return 0; |
414 | |
415 | tfm = crypto_alloc_comp(pool->tfm_name, 0, 0); |
416 | if (IS_ERR_OR_NULL(tfm)) { |
417 | pr_err("could not alloc crypto comp %s : %ld\n" , |
418 | pool->tfm_name, PTR_ERR(tfm)); |
419 | return -ENOMEM; |
420 | } |
421 | *per_cpu_ptr(pool->tfm, cpu) = tfm; |
422 | return 0; |
423 | } |
424 | |
425 | static int zswap_cpu_comp_dead(unsigned int cpu, struct hlist_node *node) |
426 | { |
427 | struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node); |
428 | struct crypto_comp *tfm; |
429 | |
430 | tfm = *per_cpu_ptr(pool->tfm, cpu); |
431 | if (!IS_ERR_OR_NULL(tfm)) |
432 | crypto_free_comp(tfm); |
433 | *per_cpu_ptr(pool->tfm, cpu) = NULL; |
434 | return 0; |
435 | } |
436 | |
437 | /********************************* |
438 | * pool functions |
439 | **********************************/ |
440 | |
441 | static struct zswap_pool *__zswap_pool_current(void) |
442 | { |
443 | struct zswap_pool *pool; |
444 | |
445 | pool = list_first_or_null_rcu(&zswap_pools, typeof(*pool), list); |
446 | WARN_ONCE(!pool && zswap_has_pool, |
447 | "%s: no page storage pool!\n" , __func__); |
448 | |
449 | return pool; |
450 | } |
451 | |
452 | static struct zswap_pool *zswap_pool_current(void) |
453 | { |
454 | assert_spin_locked(&zswap_pools_lock); |
455 | |
456 | return __zswap_pool_current(); |
457 | } |
458 | |
459 | static struct zswap_pool *zswap_pool_current_get(void) |
460 | { |
461 | struct zswap_pool *pool; |
462 | |
463 | rcu_read_lock(); |
464 | |
465 | pool = __zswap_pool_current(); |
466 | if (!zswap_pool_get(pool)) |
467 | pool = NULL; |
468 | |
469 | rcu_read_unlock(); |
470 | |
471 | return pool; |
472 | } |
473 | |
474 | static struct zswap_pool *zswap_pool_last_get(void) |
475 | { |
476 | struct zswap_pool *pool, *last = NULL; |
477 | |
478 | rcu_read_lock(); |
479 | |
480 | list_for_each_entry_rcu(pool, &zswap_pools, list) |
481 | last = pool; |
482 | WARN_ONCE(!last && zswap_has_pool, |
483 | "%s: no page storage pool!\n" , __func__); |
484 | if (!zswap_pool_get(last)) |
485 | last = NULL; |
486 | |
487 | rcu_read_unlock(); |
488 | |
489 | return last; |
490 | } |
491 | |
492 | /* type and compressor must be null-terminated */ |
493 | static struct zswap_pool *zswap_pool_find_get(char *type, char *compressor) |
494 | { |
495 | struct zswap_pool *pool; |
496 | |
497 | assert_spin_locked(&zswap_pools_lock); |
498 | |
499 | list_for_each_entry_rcu(pool, &zswap_pools, list) { |
500 | if (strcmp(pool->tfm_name, compressor)) |
501 | continue; |
502 | if (strcmp(zpool_get_type(pool->zpool), type)) |
503 | continue; |
504 | /* if we can't get it, it's about to be destroyed */ |
505 | if (!zswap_pool_get(pool)) |
506 | continue; |
507 | return pool; |
508 | } |
509 | |
510 | return NULL; |
511 | } |
512 | |
513 | static struct zswap_pool *zswap_pool_create(char *type, char *compressor) |
514 | { |
515 | struct zswap_pool *pool; |
516 | char name[38]; /* 'zswap' + 32 char (max) num + \0 */ |
517 | gfp_t gfp = __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM; |
518 | int ret; |
519 | |
520 | if (!zswap_has_pool) { |
521 | /* if either are unset, pool initialization failed, and we |
522 | * need both params to be set correctly before trying to |
523 | * create a pool. |
524 | */ |
525 | if (!strcmp(type, ZSWAP_PARAM_UNSET)) |
526 | return NULL; |
527 | if (!strcmp(compressor, ZSWAP_PARAM_UNSET)) |
528 | return NULL; |
529 | } |
530 | |
531 | pool = kzalloc(sizeof(*pool), GFP_KERNEL); |
532 | if (!pool) |
533 | return NULL; |
534 | |
535 | /* unique name for each pool specifically required by zsmalloc */ |
536 | snprintf(name, 38, "zswap%x" , atomic_inc_return(&zswap_pools_count)); |
537 | |
538 | pool->zpool = zpool_create_pool(type, name, gfp, &zswap_zpool_ops); |
539 | if (!pool->zpool) { |
540 | pr_err("%s zpool not available\n" , type); |
541 | goto error; |
542 | } |
543 | pr_debug("using %s zpool\n" , zpool_get_type(pool->zpool)); |
544 | |
545 | strlcpy(pool->tfm_name, compressor, sizeof(pool->tfm_name)); |
546 | pool->tfm = alloc_percpu(struct crypto_comp *); |
547 | if (!pool->tfm) { |
548 | pr_err("percpu alloc failed\n" ); |
549 | goto error; |
550 | } |
551 | |
552 | ret = cpuhp_state_add_instance(CPUHP_MM_ZSWP_POOL_PREPARE, |
553 | &pool->node); |
554 | if (ret) |
555 | goto error; |
556 | pr_debug("using %s compressor\n" , pool->tfm_name); |
557 | |
558 | /* being the current pool takes 1 ref; this func expects the |
559 | * caller to always add the new pool as the current pool |
560 | */ |
561 | kref_init(&pool->kref); |
562 | INIT_LIST_HEAD(&pool->list); |
563 | |
564 | zswap_pool_debug("created" , pool); |
565 | |
566 | return pool; |
567 | |
568 | error: |
569 | free_percpu(pool->tfm); |
570 | if (pool->zpool) |
571 | zpool_destroy_pool(pool->zpool); |
572 | kfree(pool); |
573 | return NULL; |
574 | } |
575 | |
576 | static __init struct zswap_pool *__zswap_pool_create_fallback(void) |
577 | { |
578 | bool has_comp, has_zpool; |
579 | |
580 | has_comp = crypto_has_comp(zswap_compressor, 0, 0); |
581 | if (!has_comp && strcmp(zswap_compressor, ZSWAP_COMPRESSOR_DEFAULT)) { |
582 | pr_err("compressor %s not available, using default %s\n" , |
583 | zswap_compressor, ZSWAP_COMPRESSOR_DEFAULT); |
584 | param_free_charp(&zswap_compressor); |
585 | zswap_compressor = ZSWAP_COMPRESSOR_DEFAULT; |
586 | has_comp = crypto_has_comp(zswap_compressor, 0, 0); |
587 | } |
588 | if (!has_comp) { |
589 | pr_err("default compressor %s not available\n" , |
590 | zswap_compressor); |
591 | param_free_charp(&zswap_compressor); |
592 | zswap_compressor = ZSWAP_PARAM_UNSET; |
593 | } |
594 | |
595 | has_zpool = zpool_has_pool(zswap_zpool_type); |
596 | if (!has_zpool && strcmp(zswap_zpool_type, ZSWAP_ZPOOL_DEFAULT)) { |
597 | pr_err("zpool %s not available, using default %s\n" , |
598 | zswap_zpool_type, ZSWAP_ZPOOL_DEFAULT); |
599 | param_free_charp(&zswap_zpool_type); |
600 | zswap_zpool_type = ZSWAP_ZPOOL_DEFAULT; |
601 | has_zpool = zpool_has_pool(zswap_zpool_type); |
602 | } |
603 | if (!has_zpool) { |
604 | pr_err("default zpool %s not available\n" , |
605 | zswap_zpool_type); |
606 | param_free_charp(&zswap_zpool_type); |
607 | zswap_zpool_type = ZSWAP_PARAM_UNSET; |
608 | } |
609 | |
610 | if (!has_comp || !has_zpool) |
611 | return NULL; |
612 | |
613 | return zswap_pool_create(zswap_zpool_type, zswap_compressor); |
614 | } |
615 | |
616 | static void zswap_pool_destroy(struct zswap_pool *pool) |
617 | { |
618 | zswap_pool_debug("destroying" , pool); |
619 | |
620 | cpuhp_state_remove_instance(CPUHP_MM_ZSWP_POOL_PREPARE, &pool->node); |
621 | free_percpu(pool->tfm); |
622 | zpool_destroy_pool(pool->zpool); |
623 | kfree(pool); |
624 | } |
625 | |
626 | static int __must_check zswap_pool_get(struct zswap_pool *pool) |
627 | { |
628 | if (!pool) |
629 | return 0; |
630 | |
631 | return kref_get_unless_zero(&pool->kref); |
632 | } |
633 | |
634 | static void __zswap_pool_release(struct work_struct *work) |
635 | { |
636 | struct zswap_pool *pool = container_of(work, typeof(*pool), work); |
637 | |
638 | synchronize_rcu(); |
639 | |
640 | /* nobody should have been able to get a kref... */ |
641 | WARN_ON(kref_get_unless_zero(&pool->kref)); |
642 | |
643 | /* pool is now off zswap_pools list and has no references. */ |
644 | zswap_pool_destroy(pool); |
645 | } |
646 | |
647 | static void __zswap_pool_empty(struct kref *kref) |
648 | { |
649 | struct zswap_pool *pool; |
650 | |
651 | pool = container_of(kref, typeof(*pool), kref); |
652 | |
653 | spin_lock(&zswap_pools_lock); |
654 | |
655 | WARN_ON(pool == zswap_pool_current()); |
656 | |
657 | list_del_rcu(&pool->list); |
658 | |
659 | INIT_WORK(&pool->work, __zswap_pool_release); |
660 | schedule_work(&pool->work); |
661 | |
662 | spin_unlock(&zswap_pools_lock); |
663 | } |
664 | |
665 | static void zswap_pool_put(struct zswap_pool *pool) |
666 | { |
667 | kref_put(&pool->kref, __zswap_pool_empty); |
668 | } |
669 | |
670 | /********************************* |
671 | * param callbacks |
672 | **********************************/ |
673 | |
674 | /* val must be a null-terminated string */ |
675 | static int __zswap_param_set(const char *val, const struct kernel_param *kp, |
676 | char *type, char *compressor) |
677 | { |
678 | struct zswap_pool *pool, *put_pool = NULL; |
679 | char *s = strstrip((char *)val); |
680 | int ret; |
681 | |
682 | if (zswap_init_failed) { |
683 | pr_err("can't set param, initialization failed\n" ); |
684 | return -ENODEV; |
685 | } |
686 | |
687 | /* no change required */ |
688 | if (!strcmp(s, *(char **)kp->arg) && zswap_has_pool) |
689 | return 0; |
690 | |
691 | /* if this is load-time (pre-init) param setting, |
692 | * don't create a pool; that's done during init. |
693 | */ |
694 | if (!zswap_init_started) |
695 | return param_set_charp(s, kp); |
696 | |
697 | if (!type) { |
698 | if (!zpool_has_pool(s)) { |
699 | pr_err("zpool %s not available\n" , s); |
700 | return -ENOENT; |
701 | } |
702 | type = s; |
703 | } else if (!compressor) { |
704 | if (!crypto_has_comp(s, 0, 0)) { |
705 | pr_err("compressor %s not available\n" , s); |
706 | return -ENOENT; |
707 | } |
708 | compressor = s; |
709 | } else { |
710 | WARN_ON(1); |
711 | return -EINVAL; |
712 | } |
713 | |
714 | spin_lock(&zswap_pools_lock); |
715 | |
716 | pool = zswap_pool_find_get(type, compressor); |
717 | if (pool) { |
718 | zswap_pool_debug("using existing" , pool); |
719 | WARN_ON(pool == zswap_pool_current()); |
720 | list_del_rcu(&pool->list); |
721 | } |
722 | |
723 | spin_unlock(&zswap_pools_lock); |
724 | |
725 | if (!pool) |
726 | pool = zswap_pool_create(type, compressor); |
727 | |
728 | if (pool) |
729 | ret = param_set_charp(s, kp); |
730 | else |
731 | ret = -EINVAL; |
732 | |
733 | spin_lock(&zswap_pools_lock); |
734 | |
735 | if (!ret) { |
736 | put_pool = zswap_pool_current(); |
737 | list_add_rcu(&pool->list, &zswap_pools); |
738 | zswap_has_pool = true; |
739 | } else if (pool) { |
740 | /* add the possibly pre-existing pool to the end of the pools |
741 | * list; if it's new (and empty) then it'll be removed and |
742 | * destroyed by the put after we drop the lock |
743 | */ |
744 | list_add_tail_rcu(&pool->list, &zswap_pools); |
745 | put_pool = pool; |
746 | } |
747 | |
748 | spin_unlock(&zswap_pools_lock); |
749 | |
750 | if (!zswap_has_pool && !pool) { |
751 | /* if initial pool creation failed, and this pool creation also |
752 | * failed, maybe both compressor and zpool params were bad. |
753 | * Allow changing this param, so pool creation will succeed |
754 | * when the other param is changed. We already verified this |
755 | * param is ok in the zpool_has_pool() or crypto_has_comp() |
756 | * checks above. |
757 | */ |
758 | ret = param_set_charp(s, kp); |
759 | } |
760 | |
761 | /* drop the ref from either the old current pool, |
762 | * or the new pool we failed to add |
763 | */ |
764 | if (put_pool) |
765 | zswap_pool_put(put_pool); |
766 | |
767 | return ret; |
768 | } |
769 | |
770 | static int zswap_compressor_param_set(const char *val, |
771 | const struct kernel_param *kp) |
772 | { |
773 | return __zswap_param_set(val, kp, zswap_zpool_type, NULL); |
774 | } |
775 | |
776 | static int zswap_zpool_param_set(const char *val, |
777 | const struct kernel_param *kp) |
778 | { |
779 | return __zswap_param_set(val, kp, NULL, zswap_compressor); |
780 | } |
781 | |
782 | static int zswap_enabled_param_set(const char *val, |
783 | const struct kernel_param *kp) |
784 | { |
785 | if (zswap_init_failed) { |
786 | pr_err("can't enable, initialization failed\n" ); |
787 | return -ENODEV; |
788 | } |
789 | if (!zswap_has_pool && zswap_init_started) { |
790 | pr_err("can't enable, no pool configured\n" ); |
791 | return -ENODEV; |
792 | } |
793 | |
794 | return param_set_bool(val, kp); |
795 | } |
796 | |
797 | /********************************* |
798 | * writeback code |
799 | **********************************/ |
800 | /* return enum for zswap_get_swap_cache_page */ |
801 | enum zswap_get_swap_ret { |
802 | ZSWAP_SWAPCACHE_NEW, |
803 | ZSWAP_SWAPCACHE_EXIST, |
804 | ZSWAP_SWAPCACHE_FAIL, |
805 | }; |
806 | |
807 | /* |
808 | * zswap_get_swap_cache_page |
809 | * |
810 | * This is an adaption of read_swap_cache_async() |
811 | * |
812 | * This function tries to find a page with the given swap entry |
813 | * in the swapper_space address space (the swap cache). If the page |
814 | * is found, it is returned in retpage. Otherwise, a page is allocated, |
815 | * added to the swap cache, and returned in retpage. |
816 | * |
817 | * If success, the swap cache page is returned in retpage |
818 | * Returns ZSWAP_SWAPCACHE_EXIST if page was already in the swap cache |
819 | * Returns ZSWAP_SWAPCACHE_NEW if the new page needs to be populated, |
820 | * the new page is added to swapcache and locked |
821 | * Returns ZSWAP_SWAPCACHE_FAIL on error |
822 | */ |
823 | static int zswap_get_swap_cache_page(swp_entry_t entry, |
824 | struct page **retpage) |
825 | { |
826 | bool page_was_allocated; |
827 | |
828 | *retpage = __read_swap_cache_async(entry, GFP_KERNEL, |
829 | NULL, 0, &page_was_allocated); |
830 | if (page_was_allocated) |
831 | return ZSWAP_SWAPCACHE_NEW; |
832 | if (!*retpage) |
833 | return ZSWAP_SWAPCACHE_FAIL; |
834 | return ZSWAP_SWAPCACHE_EXIST; |
835 | } |
836 | |
837 | /* |
838 | * Attempts to free an entry by adding a page to the swap cache, |
839 | * decompressing the entry data into the page, and issuing a |
840 | * bio write to write the page back to the swap device. |
841 | * |
842 | * This can be thought of as a "resumed writeback" of the page |
843 | * to the swap device. We are basically resuming the same swap |
844 | * writeback path that was intercepted with the frontswap_store() |
845 | * in the first place. After the page has been decompressed into |
846 | * the swap cache, the compressed version stored by zswap can be |
847 | * freed. |
848 | */ |
849 | static int zswap_writeback_entry(struct zpool *pool, unsigned long handle) |
850 | { |
851 | struct zswap_header *zhdr; |
852 | swp_entry_t swpentry; |
853 | struct zswap_tree *tree; |
854 | pgoff_t offset; |
855 | struct zswap_entry *entry; |
856 | struct page *page; |
857 | struct crypto_comp *tfm; |
858 | u8 *src, *dst; |
859 | unsigned int dlen; |
860 | int ret; |
861 | struct writeback_control wbc = { |
862 | .sync_mode = WB_SYNC_NONE, |
863 | }; |
864 | |
865 | /* extract swpentry from data */ |
866 | zhdr = zpool_map_handle(pool, handle, ZPOOL_MM_RO); |
867 | swpentry = zhdr->swpentry; /* here */ |
868 | zpool_unmap_handle(pool, handle); |
869 | tree = zswap_trees[swp_type(swpentry)]; |
870 | offset = swp_offset(swpentry); |
871 | |
872 | /* find and ref zswap entry */ |
873 | spin_lock(&tree->lock); |
874 | entry = zswap_entry_find_get(&tree->rbroot, offset); |
875 | if (!entry) { |
876 | /* entry was invalidated */ |
877 | spin_unlock(&tree->lock); |
878 | return 0; |
879 | } |
880 | spin_unlock(&tree->lock); |
881 | BUG_ON(offset != entry->offset); |
882 | |
883 | /* try to allocate swap cache page */ |
884 | switch (zswap_get_swap_cache_page(swpentry, &page)) { |
885 | case ZSWAP_SWAPCACHE_FAIL: /* no memory or invalidate happened */ |
886 | ret = -ENOMEM; |
887 | goto fail; |
888 | |
889 | case ZSWAP_SWAPCACHE_EXIST: |
890 | /* page is already in the swap cache, ignore for now */ |
891 | put_page(page); |
892 | ret = -EEXIST; |
893 | goto fail; |
894 | |
895 | case ZSWAP_SWAPCACHE_NEW: /* page is locked */ |
896 | /* decompress */ |
897 | dlen = PAGE_SIZE; |
898 | src = (u8 *)zpool_map_handle(entry->pool->zpool, entry->handle, |
899 | ZPOOL_MM_RO) + sizeof(struct zswap_header); |
900 | dst = kmap_atomic(page); |
901 | tfm = *get_cpu_ptr(entry->pool->tfm); |
902 | ret = crypto_comp_decompress(tfm, src, entry->length, |
903 | dst, &dlen); |
904 | put_cpu_ptr(entry->pool->tfm); |
905 | kunmap_atomic(dst); |
906 | zpool_unmap_handle(entry->pool->zpool, entry->handle); |
907 | BUG_ON(ret); |
908 | BUG_ON(dlen != PAGE_SIZE); |
909 | |
910 | /* page is up to date */ |
911 | SetPageUptodate(page); |
912 | } |
913 | |
914 | /* move it to the tail of the inactive list after end_writeback */ |
915 | SetPageReclaim(page); |
916 | |
917 | /* start writeback */ |
918 | __swap_writepage(page, &wbc, end_swap_bio_write); |
919 | put_page(page); |
920 | zswap_written_back_pages++; |
921 | |
922 | spin_lock(&tree->lock); |
923 | /* drop local reference */ |
924 | zswap_entry_put(tree, entry); |
925 | |
926 | /* |
927 | * There are two possible situations for entry here: |
928 | * (1) refcount is 1(normal case), entry is valid and on the tree |
929 | * (2) refcount is 0, entry is freed and not on the tree |
930 | * because invalidate happened during writeback |
931 | * search the tree and free the entry if find entry |
932 | */ |
933 | if (entry == zswap_rb_search(&tree->rbroot, offset)) |
934 | zswap_entry_put(tree, entry); |
935 | spin_unlock(&tree->lock); |
936 | |
937 | goto end; |
938 | |
939 | /* |
940 | * if we get here due to ZSWAP_SWAPCACHE_EXIST |
941 | * a load may happening concurrently |
942 | * it is safe and okay to not free the entry |
943 | * if we free the entry in the following put |
944 | * it it either okay to return !0 |
945 | */ |
946 | fail: |
947 | spin_lock(&tree->lock); |
948 | zswap_entry_put(tree, entry); |
949 | spin_unlock(&tree->lock); |
950 | |
951 | end: |
952 | return ret; |
953 | } |
954 | |
955 | static int zswap_shrink(void) |
956 | { |
957 | struct zswap_pool *pool; |
958 | int ret; |
959 | |
960 | pool = zswap_pool_last_get(); |
961 | if (!pool) |
962 | return -ENOENT; |
963 | |
964 | ret = zpool_shrink(pool->zpool, 1, NULL); |
965 | |
966 | zswap_pool_put(pool); |
967 | |
968 | return ret; |
969 | } |
970 | |
971 | static int zswap_is_page_same_filled(void *ptr, unsigned long *value) |
972 | { |
973 | unsigned int pos; |
974 | unsigned long *page; |
975 | |
976 | page = (unsigned long *)ptr; |
977 | for (pos = 1; pos < PAGE_SIZE / sizeof(*page); pos++) { |
978 | if (page[pos] != page[0]) |
979 | return 0; |
980 | } |
981 | *value = page[0]; |
982 | return 1; |
983 | } |
984 | |
985 | static void zswap_fill_page(void *ptr, unsigned long value) |
986 | { |
987 | unsigned long *page; |
988 | |
989 | page = (unsigned long *)ptr; |
990 | memset_l(page, value, PAGE_SIZE / sizeof(unsigned long)); |
991 | } |
992 | |
993 | /********************************* |
994 | * frontswap hooks |
995 | **********************************/ |
996 | /* attempts to compress and store an single page */ |
997 | static int zswap_frontswap_store(unsigned type, pgoff_t offset, |
998 | struct page *page) |
999 | { |
1000 | struct zswap_tree *tree = zswap_trees[type]; |
1001 | struct zswap_entry *entry, *dupentry; |
1002 | struct crypto_comp *tfm; |
1003 | int ret; |
1004 | unsigned int hlen, dlen = PAGE_SIZE; |
1005 | unsigned long handle, value; |
1006 | char *buf; |
1007 | u8 *src, *dst; |
1008 | struct zswap_header zhdr = { .swpentry = swp_entry(type, offset) }; |
1009 | |
1010 | /* THP isn't supported */ |
1011 | if (PageTransHuge(page)) { |
1012 | ret = -EINVAL; |
1013 | goto reject; |
1014 | } |
1015 | |
1016 | if (!zswap_enabled || !tree) { |
1017 | ret = -ENODEV; |
1018 | goto reject; |
1019 | } |
1020 | |
1021 | /* reclaim space if needed */ |
1022 | if (zswap_is_full()) { |
1023 | zswap_pool_limit_hit++; |
1024 | if (zswap_shrink()) { |
1025 | zswap_reject_reclaim_fail++; |
1026 | ret = -ENOMEM; |
1027 | goto reject; |
1028 | } |
1029 | |
1030 | /* A second zswap_is_full() check after |
1031 | * zswap_shrink() to make sure it's now |
1032 | * under the max_pool_percent |
1033 | */ |
1034 | if (zswap_is_full()) { |
1035 | ret = -ENOMEM; |
1036 | goto reject; |
1037 | } |
1038 | } |
1039 | |
1040 | /* allocate entry */ |
1041 | entry = zswap_entry_cache_alloc(GFP_KERNEL); |
1042 | if (!entry) { |
1043 | zswap_reject_kmemcache_fail++; |
1044 | ret = -ENOMEM; |
1045 | goto reject; |
1046 | } |
1047 | |
1048 | if (zswap_same_filled_pages_enabled) { |
1049 | src = kmap_atomic(page); |
1050 | if (zswap_is_page_same_filled(src, &value)) { |
1051 | kunmap_atomic(src); |
1052 | entry->offset = offset; |
1053 | entry->length = 0; |
1054 | entry->value = value; |
1055 | atomic_inc(&zswap_same_filled_pages); |
1056 | goto insert_entry; |
1057 | } |
1058 | kunmap_atomic(src); |
1059 | } |
1060 | |
1061 | /* if entry is successfully added, it keeps the reference */ |
1062 | entry->pool = zswap_pool_current_get(); |
1063 | if (!entry->pool) { |
1064 | ret = -EINVAL; |
1065 | goto freepage; |
1066 | } |
1067 | |
1068 | /* compress */ |
1069 | dst = get_cpu_var(zswap_dstmem); |
1070 | tfm = *get_cpu_ptr(entry->pool->tfm); |
1071 | src = kmap_atomic(page); |
1072 | ret = crypto_comp_compress(tfm, src, PAGE_SIZE, dst, &dlen); |
1073 | kunmap_atomic(src); |
1074 | put_cpu_ptr(entry->pool->tfm); |
1075 | if (ret) { |
1076 | ret = -EINVAL; |
1077 | goto put_dstmem; |
1078 | } |
1079 | |
1080 | /* store */ |
1081 | hlen = zpool_evictable(entry->pool->zpool) ? sizeof(zhdr) : 0; |
1082 | ret = zpool_malloc(entry->pool->zpool, hlen + dlen, |
1083 | __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM, |
1084 | &handle); |
1085 | if (ret == -ENOSPC) { |
1086 | zswap_reject_compress_poor++; |
1087 | goto put_dstmem; |
1088 | } |
1089 | if (ret) { |
1090 | zswap_reject_alloc_fail++; |
1091 | goto put_dstmem; |
1092 | } |
1093 | buf = zpool_map_handle(entry->pool->zpool, handle, ZPOOL_MM_RW); |
1094 | memcpy(buf, &zhdr, hlen); |
1095 | memcpy(buf + hlen, dst, dlen); |
1096 | zpool_unmap_handle(entry->pool->zpool, handle); |
1097 | put_cpu_var(zswap_dstmem); |
1098 | |
1099 | /* populate entry */ |
1100 | entry->offset = offset; |
1101 | entry->handle = handle; |
1102 | entry->length = dlen; |
1103 | |
1104 | insert_entry: |
1105 | /* map */ |
1106 | spin_lock(&tree->lock); |
1107 | do { |
1108 | ret = zswap_rb_insert(&tree->rbroot, entry, &dupentry); |
1109 | if (ret == -EEXIST) { |
1110 | zswap_duplicate_entry++; |
1111 | /* remove from rbtree */ |
1112 | zswap_rb_erase(&tree->rbroot, dupentry); |
1113 | zswap_entry_put(tree, dupentry); |
1114 | } |
1115 | } while (ret == -EEXIST); |
1116 | spin_unlock(&tree->lock); |
1117 | |
1118 | /* update stats */ |
1119 | atomic_inc(&zswap_stored_pages); |
1120 | zswap_update_total_size(); |
1121 | |
1122 | return 0; |
1123 | |
1124 | put_dstmem: |
1125 | put_cpu_var(zswap_dstmem); |
1126 | zswap_pool_put(entry->pool); |
1127 | freepage: |
1128 | zswap_entry_cache_free(entry); |
1129 | reject: |
1130 | return ret; |
1131 | } |
1132 | |
1133 | /* |
1134 | * returns 0 if the page was successfully decompressed |
1135 | * return -1 on entry not found or error |
1136 | */ |
1137 | static int zswap_frontswap_load(unsigned type, pgoff_t offset, |
1138 | struct page *page) |
1139 | { |
1140 | struct zswap_tree *tree = zswap_trees[type]; |
1141 | struct zswap_entry *entry; |
1142 | struct crypto_comp *tfm; |
1143 | u8 *src, *dst; |
1144 | unsigned int dlen; |
1145 | int ret; |
1146 | |
1147 | /* find */ |
1148 | spin_lock(&tree->lock); |
1149 | entry = zswap_entry_find_get(&tree->rbroot, offset); |
1150 | if (!entry) { |
1151 | /* entry was written back */ |
1152 | spin_unlock(&tree->lock); |
1153 | return -1; |
1154 | } |
1155 | spin_unlock(&tree->lock); |
1156 | |
1157 | if (!entry->length) { |
1158 | dst = kmap_atomic(page); |
1159 | zswap_fill_page(dst, entry->value); |
1160 | kunmap_atomic(dst); |
1161 | goto freeentry; |
1162 | } |
1163 | |
1164 | /* decompress */ |
1165 | dlen = PAGE_SIZE; |
1166 | src = zpool_map_handle(entry->pool->zpool, entry->handle, ZPOOL_MM_RO); |
1167 | if (zpool_evictable(entry->pool->zpool)) |
1168 | src += sizeof(struct zswap_header); |
1169 | dst = kmap_atomic(page); |
1170 | tfm = *get_cpu_ptr(entry->pool->tfm); |
1171 | ret = crypto_comp_decompress(tfm, src, entry->length, dst, &dlen); |
1172 | put_cpu_ptr(entry->pool->tfm); |
1173 | kunmap_atomic(dst); |
1174 | zpool_unmap_handle(entry->pool->zpool, entry->handle); |
1175 | BUG_ON(ret); |
1176 | |
1177 | freeentry: |
1178 | spin_lock(&tree->lock); |
1179 | zswap_entry_put(tree, entry); |
1180 | spin_unlock(&tree->lock); |
1181 | |
1182 | return 0; |
1183 | } |
1184 | |
1185 | /* frees an entry in zswap */ |
1186 | static void zswap_frontswap_invalidate_page(unsigned type, pgoff_t offset) |
1187 | { |
1188 | struct zswap_tree *tree = zswap_trees[type]; |
1189 | struct zswap_entry *entry; |
1190 | |
1191 | /* find */ |
1192 | spin_lock(&tree->lock); |
1193 | entry = zswap_rb_search(&tree->rbroot, offset); |
1194 | if (!entry) { |
1195 | /* entry was written back */ |
1196 | spin_unlock(&tree->lock); |
1197 | return; |
1198 | } |
1199 | |
1200 | /* remove from rbtree */ |
1201 | zswap_rb_erase(&tree->rbroot, entry); |
1202 | |
1203 | /* drop the initial reference from entry creation */ |
1204 | zswap_entry_put(tree, entry); |
1205 | |
1206 | spin_unlock(&tree->lock); |
1207 | } |
1208 | |
1209 | /* frees all zswap entries for the given swap type */ |
1210 | static void zswap_frontswap_invalidate_area(unsigned type) |
1211 | { |
1212 | struct zswap_tree *tree = zswap_trees[type]; |
1213 | struct zswap_entry *entry, *n; |
1214 | |
1215 | if (!tree) |
1216 | return; |
1217 | |
1218 | /* walk the tree and free everything */ |
1219 | spin_lock(&tree->lock); |
1220 | rbtree_postorder_for_each_entry_safe(entry, n, &tree->rbroot, rbnode) |
1221 | zswap_free_entry(entry); |
1222 | tree->rbroot = RB_ROOT; |
1223 | spin_unlock(&tree->lock); |
1224 | kfree(tree); |
1225 | zswap_trees[type] = NULL; |
1226 | } |
1227 | |
1228 | static void zswap_frontswap_init(unsigned type) |
1229 | { |
1230 | struct zswap_tree *tree; |
1231 | |
1232 | tree = kzalloc(sizeof(*tree), GFP_KERNEL); |
1233 | if (!tree) { |
1234 | pr_err("alloc failed, zswap disabled for swap type %d\n" , type); |
1235 | return; |
1236 | } |
1237 | |
1238 | tree->rbroot = RB_ROOT; |
1239 | spin_lock_init(&tree->lock); |
1240 | zswap_trees[type] = tree; |
1241 | } |
1242 | |
1243 | static struct frontswap_ops zswap_frontswap_ops = { |
1244 | .store = zswap_frontswap_store, |
1245 | .load = zswap_frontswap_load, |
1246 | .invalidate_page = zswap_frontswap_invalidate_page, |
1247 | .invalidate_area = zswap_frontswap_invalidate_area, |
1248 | .init = zswap_frontswap_init |
1249 | }; |
1250 | |
1251 | /********************************* |
1252 | * debugfs functions |
1253 | **********************************/ |
1254 | #ifdef CONFIG_DEBUG_FS |
1255 | #include <linux/debugfs.h> |
1256 | |
1257 | static struct dentry *zswap_debugfs_root; |
1258 | |
1259 | static int __init zswap_debugfs_init(void) |
1260 | { |
1261 | if (!debugfs_initialized()) |
1262 | return -ENODEV; |
1263 | |
1264 | zswap_debugfs_root = debugfs_create_dir("zswap" , NULL); |
1265 | if (!zswap_debugfs_root) |
1266 | return -ENOMEM; |
1267 | |
1268 | debugfs_create_u64("pool_limit_hit" , 0444, |
1269 | zswap_debugfs_root, &zswap_pool_limit_hit); |
1270 | debugfs_create_u64("reject_reclaim_fail" , 0444, |
1271 | zswap_debugfs_root, &zswap_reject_reclaim_fail); |
1272 | debugfs_create_u64("reject_alloc_fail" , 0444, |
1273 | zswap_debugfs_root, &zswap_reject_alloc_fail); |
1274 | debugfs_create_u64("reject_kmemcache_fail" , 0444, |
1275 | zswap_debugfs_root, &zswap_reject_kmemcache_fail); |
1276 | debugfs_create_u64("reject_compress_poor" , 0444, |
1277 | zswap_debugfs_root, &zswap_reject_compress_poor); |
1278 | debugfs_create_u64("written_back_pages" , 0444, |
1279 | zswap_debugfs_root, &zswap_written_back_pages); |
1280 | debugfs_create_u64("duplicate_entry" , 0444, |
1281 | zswap_debugfs_root, &zswap_duplicate_entry); |
1282 | debugfs_create_u64("pool_total_size" , 0444, |
1283 | zswap_debugfs_root, &zswap_pool_total_size); |
1284 | debugfs_create_atomic_t("stored_pages" , 0444, |
1285 | zswap_debugfs_root, &zswap_stored_pages); |
1286 | debugfs_create_atomic_t("same_filled_pages" , 0444, |
1287 | zswap_debugfs_root, &zswap_same_filled_pages); |
1288 | |
1289 | return 0; |
1290 | } |
1291 | |
1292 | static void __exit zswap_debugfs_exit(void) |
1293 | { |
1294 | debugfs_remove_recursive(zswap_debugfs_root); |
1295 | } |
1296 | #else |
1297 | static int __init zswap_debugfs_init(void) |
1298 | { |
1299 | return 0; |
1300 | } |
1301 | |
1302 | static void __exit zswap_debugfs_exit(void) { } |
1303 | #endif |
1304 | |
1305 | /********************************* |
1306 | * module init and exit |
1307 | **********************************/ |
1308 | static int __init init_zswap(void) |
1309 | { |
1310 | struct zswap_pool *pool; |
1311 | int ret; |
1312 | |
1313 | zswap_init_started = true; |
1314 | |
1315 | if (zswap_entry_cache_create()) { |
1316 | pr_err("entry cache creation failed\n" ); |
1317 | goto cache_fail; |
1318 | } |
1319 | |
1320 | ret = cpuhp_setup_state(CPUHP_MM_ZSWP_MEM_PREPARE, "mm/zswap:prepare" , |
1321 | zswap_dstmem_prepare, zswap_dstmem_dead); |
1322 | if (ret) { |
1323 | pr_err("dstmem alloc failed\n" ); |
1324 | goto dstmem_fail; |
1325 | } |
1326 | |
1327 | ret = cpuhp_setup_state_multi(CPUHP_MM_ZSWP_POOL_PREPARE, |
1328 | "mm/zswap_pool:prepare" , |
1329 | zswap_cpu_comp_prepare, |
1330 | zswap_cpu_comp_dead); |
1331 | if (ret) |
1332 | goto hp_fail; |
1333 | |
1334 | pool = __zswap_pool_create_fallback(); |
1335 | if (pool) { |
1336 | pr_info("loaded using pool %s/%s\n" , pool->tfm_name, |
1337 | zpool_get_type(pool->zpool)); |
1338 | list_add(&pool->list, &zswap_pools); |
1339 | zswap_has_pool = true; |
1340 | } else { |
1341 | pr_err("pool creation failed\n" ); |
1342 | zswap_enabled = false; |
1343 | } |
1344 | |
1345 | frontswap_register_ops(&zswap_frontswap_ops); |
1346 | if (zswap_debugfs_init()) |
1347 | pr_warn("debugfs initialization failed\n" ); |
1348 | return 0; |
1349 | |
1350 | hp_fail: |
1351 | cpuhp_remove_state(CPUHP_MM_ZSWP_MEM_PREPARE); |
1352 | dstmem_fail: |
1353 | zswap_entry_cache_destroy(); |
1354 | cache_fail: |
1355 | /* if built-in, we aren't unloaded on failure; don't allow use */ |
1356 | zswap_init_failed = true; |
1357 | zswap_enabled = false; |
1358 | return -ENOMEM; |
1359 | } |
1360 | /* must be late so crypto has time to come up */ |
1361 | late_initcall(init_zswap); |
1362 | |
1363 | MODULE_LICENSE("GPL" ); |
1364 | MODULE_AUTHOR("Seth Jennings <sjennings@variantweb.net>" ); |
1365 | MODULE_DESCRIPTION("Compressed cache for swap pages" ); |
1366 | |