Merge tag 'm68knommu-for-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git...
[platform/kernel/linux-starfive.git] / mm / zswap.c
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * zswap.c - zswap driver file
4  *
5  * zswap is a backend for frontswap that takes pages that are in the process
6  * of being swapped out and attempts to compress and store them in a
7  * RAM-based memory pool.  This can result in a significant I/O reduction on
8  * the swap device and, in the case where decompressing from RAM is faster
9  * than reading from the swap device, can also improve workload performance.
10  *
11  * Copyright (C) 2012  Seth Jennings <sjenning@linux.vnet.ibm.com>
12 */
13
14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15
16 #include <linux/module.h>
17 #include <linux/cpu.h>
18 #include <linux/highmem.h>
19 #include <linux/slab.h>
20 #include <linux/spinlock.h>
21 #include <linux/types.h>
22 #include <linux/atomic.h>
23 #include <linux/frontswap.h>
24 #include <linux/rbtree.h>
25 #include <linux/swap.h>
26 #include <linux/crypto.h>
27 #include <linux/scatterlist.h>
28 #include <linux/mempool.h>
29 #include <linux/zpool.h>
30 #include <crypto/acompress.h>
31
32 #include <linux/mm_types.h>
33 #include <linux/page-flags.h>
34 #include <linux/swapops.h>
35 #include <linux/writeback.h>
36 #include <linux/pagemap.h>
37 #include <linux/workqueue.h>
38
39 /*********************************
40 * statistics
41 **********************************/
42 /* Total bytes used by the compressed storage */
43 static u64 zswap_pool_total_size;
44 /* The number of compressed pages currently stored in zswap */
45 static atomic_t zswap_stored_pages = ATOMIC_INIT(0);
46 /* The number of same-value filled pages currently stored in zswap */
47 static atomic_t zswap_same_filled_pages = ATOMIC_INIT(0);
48
49 /*
50  * The statistics below are not protected from concurrent access for
51  * performance reasons so they may not be a 100% accurate.  However,
52  * they do provide useful information on roughly how many times a
53  * certain event is occurring.
54 */
55
56 /* Pool limit was hit (see zswap_max_pool_percent) */
57 static u64 zswap_pool_limit_hit;
58 /* Pages written back when pool limit was reached */
59 static u64 zswap_written_back_pages;
60 /* Store failed due to a reclaim failure after pool limit was reached */
61 static u64 zswap_reject_reclaim_fail;
62 /* Compressed page was too big for the allocator to (optimally) store */
63 static u64 zswap_reject_compress_poor;
64 /* Store failed because underlying allocator could not get memory */
65 static u64 zswap_reject_alloc_fail;
66 /* Store failed because the entry metadata could not be allocated (rare) */
67 static u64 zswap_reject_kmemcache_fail;
68 /* Duplicate store was encountered (rare) */
69 static u64 zswap_duplicate_entry;
70
71 /* Shrinker work queue */
72 static struct workqueue_struct *shrink_wq;
73 /* Pool limit was hit, we need to calm down */
74 static bool zswap_pool_reached_full;
75
76 /*********************************
77 * tunables
78 **********************************/
79
80 #define ZSWAP_PARAM_UNSET ""
81
82 /* Enable/disable zswap */
83 static bool zswap_enabled = IS_ENABLED(CONFIG_ZSWAP_DEFAULT_ON);
84 static int zswap_enabled_param_set(const char *,
85                                    const struct kernel_param *);
86 static const struct kernel_param_ops zswap_enabled_param_ops = {
87         .set =          zswap_enabled_param_set,
88         .get =          param_get_bool,
89 };
90 module_param_cb(enabled, &zswap_enabled_param_ops, &zswap_enabled, 0644);
91
92 /* Crypto compressor to use */
93 static char *zswap_compressor = CONFIG_ZSWAP_COMPRESSOR_DEFAULT;
94 static int zswap_compressor_param_set(const char *,
95                                       const struct kernel_param *);
96 static const struct kernel_param_ops zswap_compressor_param_ops = {
97         .set =          zswap_compressor_param_set,
98         .get =          param_get_charp,
99         .free =         param_free_charp,
100 };
101 module_param_cb(compressor, &zswap_compressor_param_ops,
102                 &zswap_compressor, 0644);
103
104 /* Compressed storage zpool to use */
105 static char *zswap_zpool_type = CONFIG_ZSWAP_ZPOOL_DEFAULT;
106 static int zswap_zpool_param_set(const char *, const struct kernel_param *);
107 static const struct kernel_param_ops zswap_zpool_param_ops = {
108         .set =          zswap_zpool_param_set,
109         .get =          param_get_charp,
110         .free =         param_free_charp,
111 };
112 module_param_cb(zpool, &zswap_zpool_param_ops, &zswap_zpool_type, 0644);
113
114 /* The maximum percentage of memory that the compressed pool can occupy */
115 static unsigned int zswap_max_pool_percent = 20;
116 module_param_named(max_pool_percent, zswap_max_pool_percent, uint, 0644);
117
118 /* The threshold for accepting new pages after the max_pool_percent was hit */
119 static unsigned int zswap_accept_thr_percent = 90; /* of max pool size */
120 module_param_named(accept_threshold_percent, zswap_accept_thr_percent,
121                    uint, 0644);
122
123 /*
124  * Enable/disable handling same-value filled pages (enabled by default).
125  * If disabled every page is considered non-same-value filled.
126  */
127 static bool zswap_same_filled_pages_enabled = true;
128 module_param_named(same_filled_pages_enabled, zswap_same_filled_pages_enabled,
129                    bool, 0644);
130
131 /* Enable/disable handling non-same-value filled pages (enabled by default) */
132 static bool zswap_non_same_filled_pages_enabled = true;
133 module_param_named(non_same_filled_pages_enabled, zswap_non_same_filled_pages_enabled,
134                    bool, 0644);
135
136 /*********************************
137 * data structures
138 **********************************/
139
140 struct crypto_acomp_ctx {
141         struct crypto_acomp *acomp;
142         struct acomp_req *req;
143         struct crypto_wait wait;
144         u8 *dstmem;
145         struct mutex *mutex;
146 };
147
148 struct zswap_pool {
149         struct zpool *zpool;
150         struct crypto_acomp_ctx __percpu *acomp_ctx;
151         struct kref kref;
152         struct list_head list;
153         struct work_struct release_work;
154         struct work_struct shrink_work;
155         struct hlist_node node;
156         char tfm_name[CRYPTO_MAX_ALG_NAME];
157 };
158
159 /*
160  * struct zswap_entry
161  *
162  * This structure contains the metadata for tracking a single compressed
163  * page within zswap.
164  *
165  * rbnode - links the entry into red-black tree for the appropriate swap type
166  * offset - the swap offset for the entry.  Index into the red-black tree.
167  * refcount - the number of outstanding reference to the entry. This is needed
168  *            to protect against premature freeing of the entry by code
169  *            concurrent calls to load, invalidate, and writeback.  The lock
170  *            for the zswap_tree structure that contains the entry must
171  *            be held while changing the refcount.  Since the lock must
172  *            be held, there is no reason to also make refcount atomic.
173  * length - the length in bytes of the compressed page data.  Needed during
174  *          decompression. For a same value filled page length is 0.
175  * pool - the zswap_pool the entry's data is in
176  * handle - zpool allocation handle that stores the compressed page data
177  * value - value of the same-value filled pages which have same content
178  */
179 struct zswap_entry {
180         struct rb_node rbnode;
181         pgoff_t offset;
182         int refcount;
183         unsigned int length;
184         struct zswap_pool *pool;
185         union {
186                 unsigned long handle;
187                 unsigned long value;
188         };
189 };
190
191 struct zswap_header {
192         swp_entry_t swpentry;
193 };
194
195 /*
196  * The tree lock in the zswap_tree struct protects a few things:
197  * - the rbtree
198  * - the refcount field of each entry in the tree
199  */
200 struct zswap_tree {
201         struct rb_root rbroot;
202         spinlock_t lock;
203 };
204
205 static struct zswap_tree *zswap_trees[MAX_SWAPFILES];
206
207 /* RCU-protected iteration */
208 static LIST_HEAD(zswap_pools);
209 /* protects zswap_pools list modification */
210 static DEFINE_SPINLOCK(zswap_pools_lock);
211 /* pool counter to provide unique names to zpool */
212 static atomic_t zswap_pools_count = ATOMIC_INIT(0);
213
214 /* used by param callback function */
215 static bool zswap_init_started;
216
217 /* fatal error during init */
218 static bool zswap_init_failed;
219
220 /* init completed, but couldn't create the initial pool */
221 static bool zswap_has_pool;
222
223 /*********************************
224 * helpers and fwd declarations
225 **********************************/
226
227 #define zswap_pool_debug(msg, p)                                \
228         pr_debug("%s pool %s/%s\n", msg, (p)->tfm_name,         \
229                  zpool_get_type((p)->zpool))
230
231 static int zswap_writeback_entry(struct zpool *pool, unsigned long handle);
232 static int zswap_pool_get(struct zswap_pool *pool);
233 static void zswap_pool_put(struct zswap_pool *pool);
234
235 static const struct zpool_ops zswap_zpool_ops = {
236         .evict = zswap_writeback_entry
237 };
238
239 static bool zswap_is_full(void)
240 {
241         return totalram_pages() * zswap_max_pool_percent / 100 <
242                         DIV_ROUND_UP(zswap_pool_total_size, PAGE_SIZE);
243 }
244
245 static bool zswap_can_accept(void)
246 {
247         return totalram_pages() * zswap_accept_thr_percent / 100 *
248                                 zswap_max_pool_percent / 100 >
249                         DIV_ROUND_UP(zswap_pool_total_size, PAGE_SIZE);
250 }
251
252 static void zswap_update_total_size(void)
253 {
254         struct zswap_pool *pool;
255         u64 total = 0;
256
257         rcu_read_lock();
258
259         list_for_each_entry_rcu(pool, &zswap_pools, list)
260                 total += zpool_get_total_size(pool->zpool);
261
262         rcu_read_unlock();
263
264         zswap_pool_total_size = total;
265 }
266
267 /*********************************
268 * zswap entry functions
269 **********************************/
270 static struct kmem_cache *zswap_entry_cache;
271
272 static int __init zswap_entry_cache_create(void)
273 {
274         zswap_entry_cache = KMEM_CACHE(zswap_entry, 0);
275         return zswap_entry_cache == NULL;
276 }
277
278 static void __init zswap_entry_cache_destroy(void)
279 {
280         kmem_cache_destroy(zswap_entry_cache);
281 }
282
283 static struct zswap_entry *zswap_entry_cache_alloc(gfp_t gfp)
284 {
285         struct zswap_entry *entry;
286         entry = kmem_cache_alloc(zswap_entry_cache, gfp);
287         if (!entry)
288                 return NULL;
289         entry->refcount = 1;
290         RB_CLEAR_NODE(&entry->rbnode);
291         return entry;
292 }
293
294 static void zswap_entry_cache_free(struct zswap_entry *entry)
295 {
296         kmem_cache_free(zswap_entry_cache, entry);
297 }
298
299 /*********************************
300 * rbtree functions
301 **********************************/
302 static struct zswap_entry *zswap_rb_search(struct rb_root *root, pgoff_t offset)
303 {
304         struct rb_node *node = root->rb_node;
305         struct zswap_entry *entry;
306
307         while (node) {
308                 entry = rb_entry(node, struct zswap_entry, rbnode);
309                 if (entry->offset > offset)
310                         node = node->rb_left;
311                 else if (entry->offset < offset)
312                         node = node->rb_right;
313                 else
314                         return entry;
315         }
316         return NULL;
317 }
318
319 /*
320  * In the case that a entry with the same offset is found, a pointer to
321  * the existing entry is stored in dupentry and the function returns -EEXIST
322  */
323 static int zswap_rb_insert(struct rb_root *root, struct zswap_entry *entry,
324                         struct zswap_entry **dupentry)
325 {
326         struct rb_node **link = &root->rb_node, *parent = NULL;
327         struct zswap_entry *myentry;
328
329         while (*link) {
330                 parent = *link;
331                 myentry = rb_entry(parent, struct zswap_entry, rbnode);
332                 if (myentry->offset > entry->offset)
333                         link = &(*link)->rb_left;
334                 else if (myentry->offset < entry->offset)
335                         link = &(*link)->rb_right;
336                 else {
337                         *dupentry = myentry;
338                         return -EEXIST;
339                 }
340         }
341         rb_link_node(&entry->rbnode, parent, link);
342         rb_insert_color(&entry->rbnode, root);
343         return 0;
344 }
345
346 static void zswap_rb_erase(struct rb_root *root, struct zswap_entry *entry)
347 {
348         if (!RB_EMPTY_NODE(&entry->rbnode)) {
349                 rb_erase(&entry->rbnode, root);
350                 RB_CLEAR_NODE(&entry->rbnode);
351         }
352 }
353
354 /*
355  * Carries out the common pattern of freeing and entry's zpool allocation,
356  * freeing the entry itself, and decrementing the number of stored pages.
357  */
358 static void zswap_free_entry(struct zswap_entry *entry)
359 {
360         if (!entry->length)
361                 atomic_dec(&zswap_same_filled_pages);
362         else {
363                 zpool_free(entry->pool->zpool, entry->handle);
364                 zswap_pool_put(entry->pool);
365         }
366         zswap_entry_cache_free(entry);
367         atomic_dec(&zswap_stored_pages);
368         zswap_update_total_size();
369 }
370
371 /* caller must hold the tree lock */
372 static void zswap_entry_get(struct zswap_entry *entry)
373 {
374         entry->refcount++;
375 }
376
377 /* caller must hold the tree lock
378 * remove from the tree and free it, if nobody reference the entry
379 */
380 static void zswap_entry_put(struct zswap_tree *tree,
381                         struct zswap_entry *entry)
382 {
383         int refcount = --entry->refcount;
384
385         BUG_ON(refcount < 0);
386         if (refcount == 0) {
387                 zswap_rb_erase(&tree->rbroot, entry);
388                 zswap_free_entry(entry);
389         }
390 }
391
392 /* caller must hold the tree lock */
393 static struct zswap_entry *zswap_entry_find_get(struct rb_root *root,
394                                 pgoff_t offset)
395 {
396         struct zswap_entry *entry;
397
398         entry = zswap_rb_search(root, offset);
399         if (entry)
400                 zswap_entry_get(entry);
401
402         return entry;
403 }
404
405 /*********************************
406 * per-cpu code
407 **********************************/
408 static DEFINE_PER_CPU(u8 *, zswap_dstmem);
409 /*
410  * If users dynamically change the zpool type and compressor at runtime, i.e.
411  * zswap is running, zswap can have more than one zpool on one cpu, but they
412  * are sharing dtsmem. So we need this mutex to be per-cpu.
413  */
414 static DEFINE_PER_CPU(struct mutex *, zswap_mutex);
415
416 static int zswap_dstmem_prepare(unsigned int cpu)
417 {
418         struct mutex *mutex;
419         u8 *dst;
420
421         dst = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu));
422         if (!dst)
423                 return -ENOMEM;
424
425         mutex = kmalloc_node(sizeof(*mutex), GFP_KERNEL, cpu_to_node(cpu));
426         if (!mutex) {
427                 kfree(dst);
428                 return -ENOMEM;
429         }
430
431         mutex_init(mutex);
432         per_cpu(zswap_dstmem, cpu) = dst;
433         per_cpu(zswap_mutex, cpu) = mutex;
434         return 0;
435 }
436
437 static int zswap_dstmem_dead(unsigned int cpu)
438 {
439         struct mutex *mutex;
440         u8 *dst;
441
442         mutex = per_cpu(zswap_mutex, cpu);
443         kfree(mutex);
444         per_cpu(zswap_mutex, cpu) = NULL;
445
446         dst = per_cpu(zswap_dstmem, cpu);
447         kfree(dst);
448         per_cpu(zswap_dstmem, cpu) = NULL;
449
450         return 0;
451 }
452
453 static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
454 {
455         struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node);
456         struct crypto_acomp_ctx *acomp_ctx = per_cpu_ptr(pool->acomp_ctx, cpu);
457         struct crypto_acomp *acomp;
458         struct acomp_req *req;
459
460         acomp = crypto_alloc_acomp_node(pool->tfm_name, 0, 0, cpu_to_node(cpu));
461         if (IS_ERR(acomp)) {
462                 pr_err("could not alloc crypto acomp %s : %ld\n",
463                                 pool->tfm_name, PTR_ERR(acomp));
464                 return PTR_ERR(acomp);
465         }
466         acomp_ctx->acomp = acomp;
467
468         req = acomp_request_alloc(acomp_ctx->acomp);
469         if (!req) {
470                 pr_err("could not alloc crypto acomp_request %s\n",
471                        pool->tfm_name);
472                 crypto_free_acomp(acomp_ctx->acomp);
473                 return -ENOMEM;
474         }
475         acomp_ctx->req = req;
476
477         crypto_init_wait(&acomp_ctx->wait);
478         /*
479          * if the backend of acomp is async zip, crypto_req_done() will wakeup
480          * crypto_wait_req(); if the backend of acomp is scomp, the callback
481          * won't be called, crypto_wait_req() will return without blocking.
482          */
483         acomp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
484                                    crypto_req_done, &acomp_ctx->wait);
485
486         acomp_ctx->mutex = per_cpu(zswap_mutex, cpu);
487         acomp_ctx->dstmem = per_cpu(zswap_dstmem, cpu);
488
489         return 0;
490 }
491
492 static int zswap_cpu_comp_dead(unsigned int cpu, struct hlist_node *node)
493 {
494         struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node);
495         struct crypto_acomp_ctx *acomp_ctx = per_cpu_ptr(pool->acomp_ctx, cpu);
496
497         if (!IS_ERR_OR_NULL(acomp_ctx)) {
498                 if (!IS_ERR_OR_NULL(acomp_ctx->req))
499                         acomp_request_free(acomp_ctx->req);
500                 if (!IS_ERR_OR_NULL(acomp_ctx->acomp))
501                         crypto_free_acomp(acomp_ctx->acomp);
502         }
503
504         return 0;
505 }
506
507 /*********************************
508 * pool functions
509 **********************************/
510
511 static struct zswap_pool *__zswap_pool_current(void)
512 {
513         struct zswap_pool *pool;
514
515         pool = list_first_or_null_rcu(&zswap_pools, typeof(*pool), list);
516         WARN_ONCE(!pool && zswap_has_pool,
517                   "%s: no page storage pool!\n", __func__);
518
519         return pool;
520 }
521
522 static struct zswap_pool *zswap_pool_current(void)
523 {
524         assert_spin_locked(&zswap_pools_lock);
525
526         return __zswap_pool_current();
527 }
528
529 static struct zswap_pool *zswap_pool_current_get(void)
530 {
531         struct zswap_pool *pool;
532
533         rcu_read_lock();
534
535         pool = __zswap_pool_current();
536         if (!zswap_pool_get(pool))
537                 pool = NULL;
538
539         rcu_read_unlock();
540
541         return pool;
542 }
543
544 static struct zswap_pool *zswap_pool_last_get(void)
545 {
546         struct zswap_pool *pool, *last = NULL;
547
548         rcu_read_lock();
549
550         list_for_each_entry_rcu(pool, &zswap_pools, list)
551                 last = pool;
552         WARN_ONCE(!last && zswap_has_pool,
553                   "%s: no page storage pool!\n", __func__);
554         if (!zswap_pool_get(last))
555                 last = NULL;
556
557         rcu_read_unlock();
558
559         return last;
560 }
561
562 /* type and compressor must be null-terminated */
563 static struct zswap_pool *zswap_pool_find_get(char *type, char *compressor)
564 {
565         struct zswap_pool *pool;
566
567         assert_spin_locked(&zswap_pools_lock);
568
569         list_for_each_entry_rcu(pool, &zswap_pools, list) {
570                 if (strcmp(pool->tfm_name, compressor))
571                         continue;
572                 if (strcmp(zpool_get_type(pool->zpool), type))
573                         continue;
574                 /* if we can't get it, it's about to be destroyed */
575                 if (!zswap_pool_get(pool))
576                         continue;
577                 return pool;
578         }
579
580         return NULL;
581 }
582
583 static void shrink_worker(struct work_struct *w)
584 {
585         struct zswap_pool *pool = container_of(w, typeof(*pool),
586                                                 shrink_work);
587
588         if (zpool_shrink(pool->zpool, 1, NULL))
589                 zswap_reject_reclaim_fail++;
590         zswap_pool_put(pool);
591 }
592
593 static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
594 {
595         struct zswap_pool *pool;
596         char name[38]; /* 'zswap' + 32 char (max) num + \0 */
597         gfp_t gfp = __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM;
598         int ret;
599
600         if (!zswap_has_pool) {
601                 /* if either are unset, pool initialization failed, and we
602                  * need both params to be set correctly before trying to
603                  * create a pool.
604                  */
605                 if (!strcmp(type, ZSWAP_PARAM_UNSET))
606                         return NULL;
607                 if (!strcmp(compressor, ZSWAP_PARAM_UNSET))
608                         return NULL;
609         }
610
611         pool = kzalloc(sizeof(*pool), GFP_KERNEL);
612         if (!pool)
613                 return NULL;
614
615         /* unique name for each pool specifically required by zsmalloc */
616         snprintf(name, 38, "zswap%x", atomic_inc_return(&zswap_pools_count));
617
618         pool->zpool = zpool_create_pool(type, name, gfp, &zswap_zpool_ops);
619         if (!pool->zpool) {
620                 pr_err("%s zpool not available\n", type);
621                 goto error;
622         }
623         pr_debug("using %s zpool\n", zpool_get_type(pool->zpool));
624
625         strscpy(pool->tfm_name, compressor, sizeof(pool->tfm_name));
626
627         pool->acomp_ctx = alloc_percpu(*pool->acomp_ctx);
628         if (!pool->acomp_ctx) {
629                 pr_err("percpu alloc failed\n");
630                 goto error;
631         }
632
633         ret = cpuhp_state_add_instance(CPUHP_MM_ZSWP_POOL_PREPARE,
634                                        &pool->node);
635         if (ret)
636                 goto error;
637         pr_debug("using %s compressor\n", pool->tfm_name);
638
639         /* being the current pool takes 1 ref; this func expects the
640          * caller to always add the new pool as the current pool
641          */
642         kref_init(&pool->kref);
643         INIT_LIST_HEAD(&pool->list);
644         INIT_WORK(&pool->shrink_work, shrink_worker);
645
646         zswap_pool_debug("created", pool);
647
648         return pool;
649
650 error:
651         if (pool->acomp_ctx)
652                 free_percpu(pool->acomp_ctx);
653         if (pool->zpool)
654                 zpool_destroy_pool(pool->zpool);
655         kfree(pool);
656         return NULL;
657 }
658
659 static __init struct zswap_pool *__zswap_pool_create_fallback(void)
660 {
661         bool has_comp, has_zpool;
662
663         has_comp = crypto_has_acomp(zswap_compressor, 0, 0);
664         if (!has_comp && strcmp(zswap_compressor,
665                                 CONFIG_ZSWAP_COMPRESSOR_DEFAULT)) {
666                 pr_err("compressor %s not available, using default %s\n",
667                        zswap_compressor, CONFIG_ZSWAP_COMPRESSOR_DEFAULT);
668                 param_free_charp(&zswap_compressor);
669                 zswap_compressor = CONFIG_ZSWAP_COMPRESSOR_DEFAULT;
670                 has_comp = crypto_has_acomp(zswap_compressor, 0, 0);
671         }
672         if (!has_comp) {
673                 pr_err("default compressor %s not available\n",
674                        zswap_compressor);
675                 param_free_charp(&zswap_compressor);
676                 zswap_compressor = ZSWAP_PARAM_UNSET;
677         }
678
679         has_zpool = zpool_has_pool(zswap_zpool_type);
680         if (!has_zpool && strcmp(zswap_zpool_type,
681                                  CONFIG_ZSWAP_ZPOOL_DEFAULT)) {
682                 pr_err("zpool %s not available, using default %s\n",
683                        zswap_zpool_type, CONFIG_ZSWAP_ZPOOL_DEFAULT);
684                 param_free_charp(&zswap_zpool_type);
685                 zswap_zpool_type = CONFIG_ZSWAP_ZPOOL_DEFAULT;
686                 has_zpool = zpool_has_pool(zswap_zpool_type);
687         }
688         if (!has_zpool) {
689                 pr_err("default zpool %s not available\n",
690                        zswap_zpool_type);
691                 param_free_charp(&zswap_zpool_type);
692                 zswap_zpool_type = ZSWAP_PARAM_UNSET;
693         }
694
695         if (!has_comp || !has_zpool)
696                 return NULL;
697
698         return zswap_pool_create(zswap_zpool_type, zswap_compressor);
699 }
700
701 static void zswap_pool_destroy(struct zswap_pool *pool)
702 {
703         zswap_pool_debug("destroying", pool);
704
705         cpuhp_state_remove_instance(CPUHP_MM_ZSWP_POOL_PREPARE, &pool->node);
706         free_percpu(pool->acomp_ctx);
707         zpool_destroy_pool(pool->zpool);
708         kfree(pool);
709 }
710
711 static int __must_check zswap_pool_get(struct zswap_pool *pool)
712 {
713         if (!pool)
714                 return 0;
715
716         return kref_get_unless_zero(&pool->kref);
717 }
718
719 static void __zswap_pool_release(struct work_struct *work)
720 {
721         struct zswap_pool *pool = container_of(work, typeof(*pool),
722                                                 release_work);
723
724         synchronize_rcu();
725
726         /* nobody should have been able to get a kref... */
727         WARN_ON(kref_get_unless_zero(&pool->kref));
728
729         /* pool is now off zswap_pools list and has no references. */
730         zswap_pool_destroy(pool);
731 }
732
733 static void __zswap_pool_empty(struct kref *kref)
734 {
735         struct zswap_pool *pool;
736
737         pool = container_of(kref, typeof(*pool), kref);
738
739         spin_lock(&zswap_pools_lock);
740
741         WARN_ON(pool == zswap_pool_current());
742
743         list_del_rcu(&pool->list);
744
745         INIT_WORK(&pool->release_work, __zswap_pool_release);
746         schedule_work(&pool->release_work);
747
748         spin_unlock(&zswap_pools_lock);
749 }
750
751 static void zswap_pool_put(struct zswap_pool *pool)
752 {
753         kref_put(&pool->kref, __zswap_pool_empty);
754 }
755
756 /*********************************
757 * param callbacks
758 **********************************/
759
760 /* val must be a null-terminated string */
761 static int __zswap_param_set(const char *val, const struct kernel_param *kp,
762                              char *type, char *compressor)
763 {
764         struct zswap_pool *pool, *put_pool = NULL;
765         char *s = strstrip((char *)val);
766         int ret;
767
768         if (zswap_init_failed) {
769                 pr_err("can't set param, initialization failed\n");
770                 return -ENODEV;
771         }
772
773         /* no change required */
774         if (!strcmp(s, *(char **)kp->arg) && zswap_has_pool)
775                 return 0;
776
777         /* if this is load-time (pre-init) param setting,
778          * don't create a pool; that's done during init.
779          */
780         if (!zswap_init_started)
781                 return param_set_charp(s, kp);
782
783         if (!type) {
784                 if (!zpool_has_pool(s)) {
785                         pr_err("zpool %s not available\n", s);
786                         return -ENOENT;
787                 }
788                 type = s;
789         } else if (!compressor) {
790                 if (!crypto_has_acomp(s, 0, 0)) {
791                         pr_err("compressor %s not available\n", s);
792                         return -ENOENT;
793                 }
794                 compressor = s;
795         } else {
796                 WARN_ON(1);
797                 return -EINVAL;
798         }
799
800         spin_lock(&zswap_pools_lock);
801
802         pool = zswap_pool_find_get(type, compressor);
803         if (pool) {
804                 zswap_pool_debug("using existing", pool);
805                 WARN_ON(pool == zswap_pool_current());
806                 list_del_rcu(&pool->list);
807         }
808
809         spin_unlock(&zswap_pools_lock);
810
811         if (!pool)
812                 pool = zswap_pool_create(type, compressor);
813
814         if (pool)
815                 ret = param_set_charp(s, kp);
816         else
817                 ret = -EINVAL;
818
819         spin_lock(&zswap_pools_lock);
820
821         if (!ret) {
822                 put_pool = zswap_pool_current();
823                 list_add_rcu(&pool->list, &zswap_pools);
824                 zswap_has_pool = true;
825         } else if (pool) {
826                 /* add the possibly pre-existing pool to the end of the pools
827                  * list; if it's new (and empty) then it'll be removed and
828                  * destroyed by the put after we drop the lock
829                  */
830                 list_add_tail_rcu(&pool->list, &zswap_pools);
831                 put_pool = pool;
832         }
833
834         spin_unlock(&zswap_pools_lock);
835
836         if (!zswap_has_pool && !pool) {
837                 /* if initial pool creation failed, and this pool creation also
838                  * failed, maybe both compressor and zpool params were bad.
839                  * Allow changing this param, so pool creation will succeed
840                  * when the other param is changed. We already verified this
841                  * param is ok in the zpool_has_pool() or crypto_has_acomp()
842                  * checks above.
843                  */
844                 ret = param_set_charp(s, kp);
845         }
846
847         /* drop the ref from either the old current pool,
848          * or the new pool we failed to add
849          */
850         if (put_pool)
851                 zswap_pool_put(put_pool);
852
853         return ret;
854 }
855
856 static int zswap_compressor_param_set(const char *val,
857                                       const struct kernel_param *kp)
858 {
859         return __zswap_param_set(val, kp, zswap_zpool_type, NULL);
860 }
861
862 static int zswap_zpool_param_set(const char *val,
863                                  const struct kernel_param *kp)
864 {
865         return __zswap_param_set(val, kp, NULL, zswap_compressor);
866 }
867
868 static int zswap_enabled_param_set(const char *val,
869                                    const struct kernel_param *kp)
870 {
871         if (zswap_init_failed) {
872                 pr_err("can't enable, initialization failed\n");
873                 return -ENODEV;
874         }
875         if (!zswap_has_pool && zswap_init_started) {
876                 pr_err("can't enable, no pool configured\n");
877                 return -ENODEV;
878         }
879
880         return param_set_bool(val, kp);
881 }
882
883 /*********************************
884 * writeback code
885 **********************************/
886 /* return enum for zswap_get_swap_cache_page */
887 enum zswap_get_swap_ret {
888         ZSWAP_SWAPCACHE_NEW,
889         ZSWAP_SWAPCACHE_EXIST,
890         ZSWAP_SWAPCACHE_FAIL,
891 };
892
893 /*
894  * zswap_get_swap_cache_page
895  *
896  * This is an adaption of read_swap_cache_async()
897  *
898  * This function tries to find a page with the given swap entry
899  * in the swapper_space address space (the swap cache).  If the page
900  * is found, it is returned in retpage.  Otherwise, a page is allocated,
901  * added to the swap cache, and returned in retpage.
902  *
903  * If success, the swap cache page is returned in retpage
904  * Returns ZSWAP_SWAPCACHE_EXIST if page was already in the swap cache
905  * Returns ZSWAP_SWAPCACHE_NEW if the new page needs to be populated,
906  *     the new page is added to swapcache and locked
907  * Returns ZSWAP_SWAPCACHE_FAIL on error
908  */
909 static int zswap_get_swap_cache_page(swp_entry_t entry,
910                                 struct page **retpage)
911 {
912         bool page_was_allocated;
913
914         *retpage = __read_swap_cache_async(entry, GFP_KERNEL,
915                         NULL, 0, &page_was_allocated);
916         if (page_was_allocated)
917                 return ZSWAP_SWAPCACHE_NEW;
918         if (!*retpage)
919                 return ZSWAP_SWAPCACHE_FAIL;
920         return ZSWAP_SWAPCACHE_EXIST;
921 }
922
923 /*
924  * Attempts to free an entry by adding a page to the swap cache,
925  * decompressing the entry data into the page, and issuing a
926  * bio write to write the page back to the swap device.
927  *
928  * This can be thought of as a "resumed writeback" of the page
929  * to the swap device.  We are basically resuming the same swap
930  * writeback path that was intercepted with the frontswap_store()
931  * in the first place.  After the page has been decompressed into
932  * the swap cache, the compressed version stored by zswap can be
933  * freed.
934  */
935 static int zswap_writeback_entry(struct zpool *pool, unsigned long handle)
936 {
937         struct zswap_header *zhdr;
938         swp_entry_t swpentry;
939         struct zswap_tree *tree;
940         pgoff_t offset;
941         struct zswap_entry *entry;
942         struct page *page;
943         struct scatterlist input, output;
944         struct crypto_acomp_ctx *acomp_ctx;
945
946         u8 *src, *tmp = NULL;
947         unsigned int dlen;
948         int ret;
949         struct writeback_control wbc = {
950                 .sync_mode = WB_SYNC_NONE,
951         };
952
953         if (!zpool_can_sleep_mapped(pool)) {
954                 tmp = kmalloc(PAGE_SIZE, GFP_ATOMIC);
955                 if (!tmp)
956                         return -ENOMEM;
957         }
958
959         /* extract swpentry from data */
960         zhdr = zpool_map_handle(pool, handle, ZPOOL_MM_RO);
961         swpentry = zhdr->swpentry; /* here */
962         tree = zswap_trees[swp_type(swpentry)];
963         offset = swp_offset(swpentry);
964
965         /* find and ref zswap entry */
966         spin_lock(&tree->lock);
967         entry = zswap_entry_find_get(&tree->rbroot, offset);
968         if (!entry) {
969                 /* entry was invalidated */
970                 spin_unlock(&tree->lock);
971                 zpool_unmap_handle(pool, handle);
972                 kfree(tmp);
973                 return 0;
974         }
975         spin_unlock(&tree->lock);
976         BUG_ON(offset != entry->offset);
977
978         src = (u8 *)zhdr + sizeof(struct zswap_header);
979         if (!zpool_can_sleep_mapped(pool)) {
980                 memcpy(tmp, src, entry->length);
981                 src = tmp;
982                 zpool_unmap_handle(pool, handle);
983         }
984
985         /* try to allocate swap cache page */
986         switch (zswap_get_swap_cache_page(swpentry, &page)) {
987         case ZSWAP_SWAPCACHE_FAIL: /* no memory or invalidate happened */
988                 ret = -ENOMEM;
989                 goto fail;
990
991         case ZSWAP_SWAPCACHE_EXIST:
992                 /* page is already in the swap cache, ignore for now */
993                 put_page(page);
994                 ret = -EEXIST;
995                 goto fail;
996
997         case ZSWAP_SWAPCACHE_NEW: /* page is locked */
998                 /* decompress */
999                 acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx);
1000                 dlen = PAGE_SIZE;
1001
1002                 mutex_lock(acomp_ctx->mutex);
1003                 sg_init_one(&input, src, entry->length);
1004                 sg_init_table(&output, 1);
1005                 sg_set_page(&output, page, PAGE_SIZE, 0);
1006                 acomp_request_set_params(acomp_ctx->req, &input, &output, entry->length, dlen);
1007                 ret = crypto_wait_req(crypto_acomp_decompress(acomp_ctx->req), &acomp_ctx->wait);
1008                 dlen = acomp_ctx->req->dlen;
1009                 mutex_unlock(acomp_ctx->mutex);
1010
1011                 BUG_ON(ret);
1012                 BUG_ON(dlen != PAGE_SIZE);
1013
1014                 /* page is up to date */
1015                 SetPageUptodate(page);
1016         }
1017
1018         /* move it to the tail of the inactive list after end_writeback */
1019         SetPageReclaim(page);
1020
1021         /* start writeback */
1022         __swap_writepage(page, &wbc, end_swap_bio_write);
1023         put_page(page);
1024         zswap_written_back_pages++;
1025
1026         spin_lock(&tree->lock);
1027         /* drop local reference */
1028         zswap_entry_put(tree, entry);
1029
1030         /*
1031         * There are two possible situations for entry here:
1032         * (1) refcount is 1(normal case),  entry is valid and on the tree
1033         * (2) refcount is 0, entry is freed and not on the tree
1034         *     because invalidate happened during writeback
1035         *  search the tree and free the entry if find entry
1036         */
1037         if (entry == zswap_rb_search(&tree->rbroot, offset))
1038                 zswap_entry_put(tree, entry);
1039         spin_unlock(&tree->lock);
1040
1041         goto end;
1042
1043         /*
1044         * if we get here due to ZSWAP_SWAPCACHE_EXIST
1045         * a load may be happening concurrently.
1046         * it is safe and okay to not free the entry.
1047         * if we free the entry in the following put
1048         * it is also okay to return !0
1049         */
1050 fail:
1051         spin_lock(&tree->lock);
1052         zswap_entry_put(tree, entry);
1053         spin_unlock(&tree->lock);
1054
1055 end:
1056         if (zpool_can_sleep_mapped(pool))
1057                 zpool_unmap_handle(pool, handle);
1058         else
1059                 kfree(tmp);
1060
1061         return ret;
1062 }
1063
1064 static int zswap_is_page_same_filled(void *ptr, unsigned long *value)
1065 {
1066         unsigned int pos;
1067         unsigned long *page;
1068
1069         page = (unsigned long *)ptr;
1070         for (pos = 1; pos < PAGE_SIZE / sizeof(*page); pos++) {
1071                 if (page[pos] != page[0])
1072                         return 0;
1073         }
1074         *value = page[0];
1075         return 1;
1076 }
1077
1078 static void zswap_fill_page(void *ptr, unsigned long value)
1079 {
1080         unsigned long *page;
1081
1082         page = (unsigned long *)ptr;
1083         memset_l(page, value, PAGE_SIZE / sizeof(unsigned long));
1084 }
1085
1086 /*********************************
1087 * frontswap hooks
1088 **********************************/
1089 /* attempts to compress and store an single page */
1090 static int zswap_frontswap_store(unsigned type, pgoff_t offset,
1091                                 struct page *page)
1092 {
1093         struct zswap_tree *tree = zswap_trees[type];
1094         struct zswap_entry *entry, *dupentry;
1095         struct scatterlist input, output;
1096         struct crypto_acomp_ctx *acomp_ctx;
1097         int ret;
1098         unsigned int hlen, dlen = PAGE_SIZE;
1099         unsigned long handle, value;
1100         char *buf;
1101         u8 *src, *dst;
1102         struct zswap_header zhdr = { .swpentry = swp_entry(type, offset) };
1103         gfp_t gfp;
1104
1105         /* THP isn't supported */
1106         if (PageTransHuge(page)) {
1107                 ret = -EINVAL;
1108                 goto reject;
1109         }
1110
1111         if (!zswap_enabled || !tree) {
1112                 ret = -ENODEV;
1113                 goto reject;
1114         }
1115
1116         /* reclaim space if needed */
1117         if (zswap_is_full()) {
1118                 struct zswap_pool *pool;
1119
1120                 zswap_pool_limit_hit++;
1121                 zswap_pool_reached_full = true;
1122                 pool = zswap_pool_last_get();
1123                 if (pool)
1124                         queue_work(shrink_wq, &pool->shrink_work);
1125                 ret = -ENOMEM;
1126                 goto reject;
1127         }
1128
1129         if (zswap_pool_reached_full) {
1130                if (!zswap_can_accept()) {
1131                         ret = -ENOMEM;
1132                         goto reject;
1133                 } else
1134                         zswap_pool_reached_full = false;
1135         }
1136
1137         /* allocate entry */
1138         entry = zswap_entry_cache_alloc(GFP_KERNEL);
1139         if (!entry) {
1140                 zswap_reject_kmemcache_fail++;
1141                 ret = -ENOMEM;
1142                 goto reject;
1143         }
1144
1145         if (zswap_same_filled_pages_enabled) {
1146                 src = kmap_atomic(page);
1147                 if (zswap_is_page_same_filled(src, &value)) {
1148                         kunmap_atomic(src);
1149                         entry->offset = offset;
1150                         entry->length = 0;
1151                         entry->value = value;
1152                         atomic_inc(&zswap_same_filled_pages);
1153                         goto insert_entry;
1154                 }
1155                 kunmap_atomic(src);
1156         }
1157
1158         if (!zswap_non_same_filled_pages_enabled) {
1159                 ret = -EINVAL;
1160                 goto freepage;
1161         }
1162
1163         /* if entry is successfully added, it keeps the reference */
1164         entry->pool = zswap_pool_current_get();
1165         if (!entry->pool) {
1166                 ret = -EINVAL;
1167                 goto freepage;
1168         }
1169
1170         /* compress */
1171         acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx);
1172
1173         mutex_lock(acomp_ctx->mutex);
1174
1175         dst = acomp_ctx->dstmem;
1176         sg_init_table(&input, 1);
1177         sg_set_page(&input, page, PAGE_SIZE, 0);
1178
1179         /* zswap_dstmem is of size (PAGE_SIZE * 2). Reflect same in sg_list */
1180         sg_init_one(&output, dst, PAGE_SIZE * 2);
1181         acomp_request_set_params(acomp_ctx->req, &input, &output, PAGE_SIZE, dlen);
1182         /*
1183          * it maybe looks a little bit silly that we send an asynchronous request,
1184          * then wait for its completion synchronously. This makes the process look
1185          * synchronous in fact.
1186          * Theoretically, acomp supports users send multiple acomp requests in one
1187          * acomp instance, then get those requests done simultaneously. but in this
1188          * case, frontswap actually does store and load page by page, there is no
1189          * existing method to send the second page before the first page is done
1190          * in one thread doing frontswap.
1191          * but in different threads running on different cpu, we have different
1192          * acomp instance, so multiple threads can do (de)compression in parallel.
1193          */
1194         ret = crypto_wait_req(crypto_acomp_compress(acomp_ctx->req), &acomp_ctx->wait);
1195         dlen = acomp_ctx->req->dlen;
1196
1197         if (ret) {
1198                 ret = -EINVAL;
1199                 goto put_dstmem;
1200         }
1201
1202         /* store */
1203         hlen = zpool_evictable(entry->pool->zpool) ? sizeof(zhdr) : 0;
1204         gfp = __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM;
1205         if (zpool_malloc_support_movable(entry->pool->zpool))
1206                 gfp |= __GFP_HIGHMEM | __GFP_MOVABLE;
1207         ret = zpool_malloc(entry->pool->zpool, hlen + dlen, gfp, &handle);
1208         if (ret == -ENOSPC) {
1209                 zswap_reject_compress_poor++;
1210                 goto put_dstmem;
1211         }
1212         if (ret) {
1213                 zswap_reject_alloc_fail++;
1214                 goto put_dstmem;
1215         }
1216         buf = zpool_map_handle(entry->pool->zpool, handle, ZPOOL_MM_WO);
1217         memcpy(buf, &zhdr, hlen);
1218         memcpy(buf + hlen, dst, dlen);
1219         zpool_unmap_handle(entry->pool->zpool, handle);
1220         mutex_unlock(acomp_ctx->mutex);
1221
1222         /* populate entry */
1223         entry->offset = offset;
1224         entry->handle = handle;
1225         entry->length = dlen;
1226
1227 insert_entry:
1228         /* map */
1229         spin_lock(&tree->lock);
1230         do {
1231                 ret = zswap_rb_insert(&tree->rbroot, entry, &dupentry);
1232                 if (ret == -EEXIST) {
1233                         zswap_duplicate_entry++;
1234                         /* remove from rbtree */
1235                         zswap_rb_erase(&tree->rbroot, dupentry);
1236                         zswap_entry_put(tree, dupentry);
1237                 }
1238         } while (ret == -EEXIST);
1239         spin_unlock(&tree->lock);
1240
1241         /* update stats */
1242         atomic_inc(&zswap_stored_pages);
1243         zswap_update_total_size();
1244
1245         return 0;
1246
1247 put_dstmem:
1248         mutex_unlock(acomp_ctx->mutex);
1249         zswap_pool_put(entry->pool);
1250 freepage:
1251         zswap_entry_cache_free(entry);
1252 reject:
1253         return ret;
1254 }
1255
1256 /*
1257  * returns 0 if the page was successfully decompressed
1258  * return -1 on entry not found or error
1259 */
1260 static int zswap_frontswap_load(unsigned type, pgoff_t offset,
1261                                 struct page *page)
1262 {
1263         struct zswap_tree *tree = zswap_trees[type];
1264         struct zswap_entry *entry;
1265         struct scatterlist input, output;
1266         struct crypto_acomp_ctx *acomp_ctx;
1267         u8 *src, *dst, *tmp;
1268         unsigned int dlen;
1269         int ret;
1270
1271         /* find */
1272         spin_lock(&tree->lock);
1273         entry = zswap_entry_find_get(&tree->rbroot, offset);
1274         if (!entry) {
1275                 /* entry was written back */
1276                 spin_unlock(&tree->lock);
1277                 return -1;
1278         }
1279         spin_unlock(&tree->lock);
1280
1281         if (!entry->length) {
1282                 dst = kmap_atomic(page);
1283                 zswap_fill_page(dst, entry->value);
1284                 kunmap_atomic(dst);
1285                 ret = 0;
1286                 goto freeentry;
1287         }
1288
1289         if (!zpool_can_sleep_mapped(entry->pool->zpool)) {
1290
1291                 tmp = kmalloc(entry->length, GFP_ATOMIC);
1292                 if (!tmp) {
1293                         ret = -ENOMEM;
1294                         goto freeentry;
1295                 }
1296         }
1297
1298         /* decompress */
1299         dlen = PAGE_SIZE;
1300         src = zpool_map_handle(entry->pool->zpool, entry->handle, ZPOOL_MM_RO);
1301         if (zpool_evictable(entry->pool->zpool))
1302                 src += sizeof(struct zswap_header);
1303
1304         if (!zpool_can_sleep_mapped(entry->pool->zpool)) {
1305
1306                 memcpy(tmp, src, entry->length);
1307                 src = tmp;
1308
1309                 zpool_unmap_handle(entry->pool->zpool, entry->handle);
1310         }
1311
1312         acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx);
1313         mutex_lock(acomp_ctx->mutex);
1314         sg_init_one(&input, src, entry->length);
1315         sg_init_table(&output, 1);
1316         sg_set_page(&output, page, PAGE_SIZE, 0);
1317         acomp_request_set_params(acomp_ctx->req, &input, &output, entry->length, dlen);
1318         ret = crypto_wait_req(crypto_acomp_decompress(acomp_ctx->req), &acomp_ctx->wait);
1319         mutex_unlock(acomp_ctx->mutex);
1320
1321         if (zpool_can_sleep_mapped(entry->pool->zpool))
1322                 zpool_unmap_handle(entry->pool->zpool, entry->handle);
1323         else
1324                 kfree(tmp);
1325
1326         BUG_ON(ret);
1327
1328 freeentry:
1329         spin_lock(&tree->lock);
1330         zswap_entry_put(tree, entry);
1331         spin_unlock(&tree->lock);
1332
1333         return ret;
1334 }
1335
1336 /* frees an entry in zswap */
1337 static void zswap_frontswap_invalidate_page(unsigned type, pgoff_t offset)
1338 {
1339         struct zswap_tree *tree = zswap_trees[type];
1340         struct zswap_entry *entry;
1341
1342         /* find */
1343         spin_lock(&tree->lock);
1344         entry = zswap_rb_search(&tree->rbroot, offset);
1345         if (!entry) {
1346                 /* entry was written back */
1347                 spin_unlock(&tree->lock);
1348                 return;
1349         }
1350
1351         /* remove from rbtree */
1352         zswap_rb_erase(&tree->rbroot, entry);
1353
1354         /* drop the initial reference from entry creation */
1355         zswap_entry_put(tree, entry);
1356
1357         spin_unlock(&tree->lock);
1358 }
1359
1360 /* frees all zswap entries for the given swap type */
1361 static void zswap_frontswap_invalidate_area(unsigned type)
1362 {
1363         struct zswap_tree *tree = zswap_trees[type];
1364         struct zswap_entry *entry, *n;
1365
1366         if (!tree)
1367                 return;
1368
1369         /* walk the tree and free everything */
1370         spin_lock(&tree->lock);
1371         rbtree_postorder_for_each_entry_safe(entry, n, &tree->rbroot, rbnode)
1372                 zswap_free_entry(entry);
1373         tree->rbroot = RB_ROOT;
1374         spin_unlock(&tree->lock);
1375         kfree(tree);
1376         zswap_trees[type] = NULL;
1377 }
1378
1379 static void zswap_frontswap_init(unsigned type)
1380 {
1381         struct zswap_tree *tree;
1382
1383         tree = kzalloc(sizeof(*tree), GFP_KERNEL);
1384         if (!tree) {
1385                 pr_err("alloc failed, zswap disabled for swap type %d\n", type);
1386                 return;
1387         }
1388
1389         tree->rbroot = RB_ROOT;
1390         spin_lock_init(&tree->lock);
1391         zswap_trees[type] = tree;
1392 }
1393
1394 static const struct frontswap_ops zswap_frontswap_ops = {
1395         .store = zswap_frontswap_store,
1396         .load = zswap_frontswap_load,
1397         .invalidate_page = zswap_frontswap_invalidate_page,
1398         .invalidate_area = zswap_frontswap_invalidate_area,
1399         .init = zswap_frontswap_init
1400 };
1401
1402 /*********************************
1403 * debugfs functions
1404 **********************************/
1405 #ifdef CONFIG_DEBUG_FS
1406 #include <linux/debugfs.h>
1407
1408 static struct dentry *zswap_debugfs_root;
1409
1410 static int __init zswap_debugfs_init(void)
1411 {
1412         if (!debugfs_initialized())
1413                 return -ENODEV;
1414
1415         zswap_debugfs_root = debugfs_create_dir("zswap", NULL);
1416
1417         debugfs_create_u64("pool_limit_hit", 0444,
1418                            zswap_debugfs_root, &zswap_pool_limit_hit);
1419         debugfs_create_u64("reject_reclaim_fail", 0444,
1420                            zswap_debugfs_root, &zswap_reject_reclaim_fail);
1421         debugfs_create_u64("reject_alloc_fail", 0444,
1422                            zswap_debugfs_root, &zswap_reject_alloc_fail);
1423         debugfs_create_u64("reject_kmemcache_fail", 0444,
1424                            zswap_debugfs_root, &zswap_reject_kmemcache_fail);
1425         debugfs_create_u64("reject_compress_poor", 0444,
1426                            zswap_debugfs_root, &zswap_reject_compress_poor);
1427         debugfs_create_u64("written_back_pages", 0444,
1428                            zswap_debugfs_root, &zswap_written_back_pages);
1429         debugfs_create_u64("duplicate_entry", 0444,
1430                            zswap_debugfs_root, &zswap_duplicate_entry);
1431         debugfs_create_u64("pool_total_size", 0444,
1432                            zswap_debugfs_root, &zswap_pool_total_size);
1433         debugfs_create_atomic_t("stored_pages", 0444,
1434                                 zswap_debugfs_root, &zswap_stored_pages);
1435         debugfs_create_atomic_t("same_filled_pages", 0444,
1436                                 zswap_debugfs_root, &zswap_same_filled_pages);
1437
1438         return 0;
1439 }
1440 #else
1441 static int __init zswap_debugfs_init(void)
1442 {
1443         return 0;
1444 }
1445 #endif
1446
1447 /*********************************
1448 * module init and exit
1449 **********************************/
1450 static int __init init_zswap(void)
1451 {
1452         struct zswap_pool *pool;
1453         int ret;
1454
1455         zswap_init_started = true;
1456
1457         if (zswap_entry_cache_create()) {
1458                 pr_err("entry cache creation failed\n");
1459                 goto cache_fail;
1460         }
1461
1462         ret = cpuhp_setup_state(CPUHP_MM_ZSWP_MEM_PREPARE, "mm/zswap:prepare",
1463                                 zswap_dstmem_prepare, zswap_dstmem_dead);
1464         if (ret) {
1465                 pr_err("dstmem alloc failed\n");
1466                 goto dstmem_fail;
1467         }
1468
1469         ret = cpuhp_setup_state_multi(CPUHP_MM_ZSWP_POOL_PREPARE,
1470                                       "mm/zswap_pool:prepare",
1471                                       zswap_cpu_comp_prepare,
1472                                       zswap_cpu_comp_dead);
1473         if (ret)
1474                 goto hp_fail;
1475
1476         pool = __zswap_pool_create_fallback();
1477         if (pool) {
1478                 pr_info("loaded using pool %s/%s\n", pool->tfm_name,
1479                         zpool_get_type(pool->zpool));
1480                 list_add(&pool->list, &zswap_pools);
1481                 zswap_has_pool = true;
1482         } else {
1483                 pr_err("pool creation failed\n");
1484                 zswap_enabled = false;
1485         }
1486
1487         shrink_wq = create_workqueue("zswap-shrink");
1488         if (!shrink_wq)
1489                 goto fallback_fail;
1490
1491         ret = frontswap_register_ops(&zswap_frontswap_ops);
1492         if (ret)
1493                 goto destroy_wq;
1494         if (zswap_debugfs_init())
1495                 pr_warn("debugfs initialization failed\n");
1496         return 0;
1497
1498 destroy_wq:
1499         destroy_workqueue(shrink_wq);
1500 fallback_fail:
1501         if (pool)
1502                 zswap_pool_destroy(pool);
1503 hp_fail:
1504         cpuhp_remove_state(CPUHP_MM_ZSWP_MEM_PREPARE);
1505 dstmem_fail:
1506         zswap_entry_cache_destroy();
1507 cache_fail:
1508         /* if built-in, we aren't unloaded on failure; don't allow use */
1509         zswap_init_failed = true;
1510         zswap_enabled = false;
1511         return -ENOMEM;
1512 }
1513 /* must be late so crypto has time to come up */
1514 late_initcall(init_zswap);
1515
1516 MODULE_LICENSE("GPL");
1517 MODULE_AUTHOR("Seth Jennings <sjennings@variantweb.net>");
1518 MODULE_DESCRIPTION("Compressed cache for swap pages");