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Vitaly Wool9a001fc2016-05-20 16:58:30 -07001/*
2 * z3fold.c
3 *
4 * Author: Vitaly Wool <vitaly.wool@konsulko.com>
5 * Copyright (C) 2016, Sony Mobile Communications Inc.
6 *
7 * This implementation is based on zbud written by Seth Jennings.
8 *
9 * z3fold is an special purpose allocator for storing compressed pages. It
10 * can store up to three compressed pages per page which improves the
11 * compression ratio of zbud while retaining its main concepts (e. g. always
12 * storing an integral number of objects per page) and simplicity.
13 * It still has simple and deterministic reclaim properties that make it
14 * preferable to a higher density approach (with no requirement on integral
15 * number of object per page) when reclaim is used.
16 *
17 * As in zbud, pages are divided into "chunks". The size of the chunks is
18 * fixed at compile time and is determined by NCHUNKS_ORDER below.
19 *
20 * z3fold doesn't export any API and is meant to be used via zpool API.
21 */
22
23#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
24
25#include <linux/atomic.h>
Vitaly Woold30561c2017-09-06 16:24:47 -070026#include <linux/sched.h>
Vitaly Wool9a001fc2016-05-20 16:58:30 -070027#include <linux/list.h>
28#include <linux/mm.h>
29#include <linux/module.h>
Vitaly Woold30561c2017-09-06 16:24:47 -070030#include <linux/percpu.h>
Vitaly Wool9a001fc2016-05-20 16:58:30 -070031#include <linux/preempt.h>
Vitaly Woold30561c2017-09-06 16:24:47 -070032#include <linux/workqueue.h>
Vitaly Wool9a001fc2016-05-20 16:58:30 -070033#include <linux/slab.h>
34#include <linux/spinlock.h>
35#include <linux/zpool.h>
36
37/*****************
38 * Structures
39*****************/
Vitaly Woolede93212017-02-24 14:57:17 -080040struct z3fold_pool;
41struct z3fold_ops {
42 int (*evict)(struct z3fold_pool *pool, unsigned long handle);
43};
44
45enum buddy {
46 HEADLESS = 0,
47 FIRST,
48 MIDDLE,
49 LAST,
50 BUDDIES_MAX
51};
52
53/*
Vitaly Woold30561c2017-09-06 16:24:47 -070054 * struct z3fold_header - z3fold page metadata occupying first chunks of each
Vitaly Woolede93212017-02-24 14:57:17 -080055 * z3fold page, except for HEADLESS pages
Vitaly Woold30561c2017-09-06 16:24:47 -070056 * @buddy: links the z3fold page into the relevant list in the
57 * pool
Vitaly Wool2f1e5e42017-02-24 14:57:23 -080058 * @page_lock: per-page lock
Vitaly Woold30561c2017-09-06 16:24:47 -070059 * @refcount: reference count for the z3fold page
60 * @work: work_struct for page layout optimization
61 * @pool: pointer to the pool which this page belongs to
62 * @cpu: CPU which this page "belongs" to
Vitaly Woolede93212017-02-24 14:57:17 -080063 * @first_chunks: the size of the first buddy in chunks, 0 if free
64 * @middle_chunks: the size of the middle buddy in chunks, 0 if free
65 * @last_chunks: the size of the last buddy in chunks, 0 if free
66 * @first_num: the starting number (for the first handle)
67 */
68struct z3fold_header {
69 struct list_head buddy;
Vitaly Wool2f1e5e42017-02-24 14:57:23 -080070 spinlock_t page_lock;
Vitaly Wool5a27aa82017-02-24 14:57:26 -080071 struct kref refcount;
Vitaly Woold30561c2017-09-06 16:24:47 -070072 struct work_struct work;
73 struct z3fold_pool *pool;
74 short cpu;
Vitaly Woolede93212017-02-24 14:57:17 -080075 unsigned short first_chunks;
76 unsigned short middle_chunks;
77 unsigned short last_chunks;
78 unsigned short start_middle;
79 unsigned short first_num:2;
80};
81
Vitaly Wool9a001fc2016-05-20 16:58:30 -070082/*
83 * NCHUNKS_ORDER determines the internal allocation granularity, effectively
84 * adjusting internal fragmentation. It also determines the number of
85 * freelists maintained in each pool. NCHUNKS_ORDER of 6 means that the
Vitaly Woolede93212017-02-24 14:57:17 -080086 * allocation granularity will be in chunks of size PAGE_SIZE/64. Some chunks
87 * in the beginning of an allocated page are occupied by z3fold header, so
88 * NCHUNKS will be calculated to 63 (or 62 in case CONFIG_DEBUG_SPINLOCK=y),
89 * which shows the max number of free chunks in z3fold page, also there will
90 * be 63, or 62, respectively, freelists per pool.
Vitaly Wool9a001fc2016-05-20 16:58:30 -070091 */
92#define NCHUNKS_ORDER 6
93
94#define CHUNK_SHIFT (PAGE_SHIFT - NCHUNKS_ORDER)
95#define CHUNK_SIZE (1 << CHUNK_SHIFT)
Vitaly Woolede93212017-02-24 14:57:17 -080096#define ZHDR_SIZE_ALIGNED round_up(sizeof(struct z3fold_header), CHUNK_SIZE)
97#define ZHDR_CHUNKS (ZHDR_SIZE_ALIGNED >> CHUNK_SHIFT)
98#define TOTAL_CHUNKS (PAGE_SIZE >> CHUNK_SHIFT)
Vitaly Wool9a001fc2016-05-20 16:58:30 -070099#define NCHUNKS ((PAGE_SIZE - ZHDR_SIZE_ALIGNED) >> CHUNK_SHIFT)
100
zhong jiangf201ebd2017-02-22 15:46:51 -0800101#define BUDDY_MASK (0x3)
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700102
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700103/**
104 * struct z3fold_pool - stores metadata for each z3fold pool
Vitaly Woold30561c2017-09-06 16:24:47 -0700105 * @name: pool name
106 * @lock: protects pool unbuddied/lru lists
107 * @stale_lock: protects pool stale page list
108 * @unbuddied: per-cpu array of lists tracking z3fold pages that contain 2-
109 * buddies; the list each z3fold page is added to depends on
110 * the size of its free region.
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700111 * @lru: list tracking the z3fold pages in LRU order by most recently
112 * added buddy.
Vitaly Woold30561c2017-09-06 16:24:47 -0700113 * @stale: list of pages marked for freeing
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700114 * @pages_nr: number of z3fold pages in the pool.
115 * @ops: pointer to a structure of user defined operations specified at
116 * pool creation time.
Vitaly Woold30561c2017-09-06 16:24:47 -0700117 * @compact_wq: workqueue for page layout background optimization
118 * @release_wq: workqueue for safe page release
119 * @work: work_struct for safe page release
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700120 *
121 * This structure is allocated at pool creation time and maintains metadata
122 * pertaining to a particular z3fold pool.
123 */
124struct z3fold_pool {
Vitaly Woold30561c2017-09-06 16:24:47 -0700125 const char *name;
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700126 spinlock_t lock;
Vitaly Woold30561c2017-09-06 16:24:47 -0700127 spinlock_t stale_lock;
128 struct list_head *unbuddied;
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700129 struct list_head lru;
Vitaly Woold30561c2017-09-06 16:24:47 -0700130 struct list_head stale;
Vitaly Wool12d59ae2017-02-24 14:57:15 -0800131 atomic64_t pages_nr;
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700132 const struct z3fold_ops *ops;
133 struct zpool *zpool;
134 const struct zpool_ops *zpool_ops;
Vitaly Woold30561c2017-09-06 16:24:47 -0700135 struct workqueue_struct *compact_wq;
136 struct workqueue_struct *release_wq;
137 struct work_struct work;
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700138};
139
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700140/*
141 * Internal z3fold page flags
142 */
143enum z3fold_page_flags {
Vitaly Wool5a27aa82017-02-24 14:57:26 -0800144 PAGE_HEADLESS = 0,
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700145 MIDDLE_CHUNK_MAPPED,
Vitaly Woold30561c2017-09-06 16:24:47 -0700146 NEEDS_COMPACTING,
147 PAGE_STALE
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700148};
149
150/*****************
151 * Helpers
152*****************/
153
154/* Converts an allocation size in bytes to size in z3fold chunks */
155static int size_to_chunks(size_t size)
156{
157 return (size + CHUNK_SIZE - 1) >> CHUNK_SHIFT;
158}
159
160#define for_each_unbuddied_list(_iter, _begin) \
161 for ((_iter) = (_begin); (_iter) < NCHUNKS; (_iter)++)
162
Vitaly Woold30561c2017-09-06 16:24:47 -0700163static void compact_page_work(struct work_struct *w);
164
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700165/* Initializes the z3fold header of a newly allocated z3fold page */
Vitaly Woold30561c2017-09-06 16:24:47 -0700166static struct z3fold_header *init_z3fold_page(struct page *page,
167 struct z3fold_pool *pool)
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700168{
169 struct z3fold_header *zhdr = page_address(page);
170
171 INIT_LIST_HEAD(&page->lru);
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700172 clear_bit(PAGE_HEADLESS, &page->private);
173 clear_bit(MIDDLE_CHUNK_MAPPED, &page->private);
Vitaly Woold30561c2017-09-06 16:24:47 -0700174 clear_bit(NEEDS_COMPACTING, &page->private);
175 clear_bit(PAGE_STALE, &page->private);
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700176
Vitaly Wool2f1e5e42017-02-24 14:57:23 -0800177 spin_lock_init(&zhdr->page_lock);
Vitaly Wool5a27aa82017-02-24 14:57:26 -0800178 kref_init(&zhdr->refcount);
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700179 zhdr->first_chunks = 0;
180 zhdr->middle_chunks = 0;
181 zhdr->last_chunks = 0;
182 zhdr->first_num = 0;
183 zhdr->start_middle = 0;
Vitaly Woold30561c2017-09-06 16:24:47 -0700184 zhdr->cpu = -1;
185 zhdr->pool = pool;
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700186 INIT_LIST_HEAD(&zhdr->buddy);
Vitaly Woold30561c2017-09-06 16:24:47 -0700187 INIT_WORK(&zhdr->work, compact_page_work);
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700188 return zhdr;
189}
190
191/* Resets the struct page fields and frees the page */
Vitaly Wool5a27aa82017-02-24 14:57:26 -0800192static void free_z3fold_page(struct page *page)
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700193{
Vitaly Wool5a27aa82017-02-24 14:57:26 -0800194 __free_page(page);
195}
196
Vitaly Wool2f1e5e42017-02-24 14:57:23 -0800197/* Lock a z3fold page */
198static inline void z3fold_page_lock(struct z3fold_header *zhdr)
199{
200 spin_lock(&zhdr->page_lock);
201}
202
Vitaly Wool76e32a22017-04-13 14:56:14 -0700203/* Try to lock a z3fold page */
204static inline int z3fold_page_trylock(struct z3fold_header *zhdr)
205{
206 return spin_trylock(&zhdr->page_lock);
207}
208
Vitaly Wool2f1e5e42017-02-24 14:57:23 -0800209/* Unlock a z3fold page */
210static inline void z3fold_page_unlock(struct z3fold_header *zhdr)
211{
212 spin_unlock(&zhdr->page_lock);
213}
214
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700215/*
216 * Encodes the handle of a particular buddy within a z3fold page
217 * Pool lock should be held as this function accesses first_num
218 */
219static unsigned long encode_handle(struct z3fold_header *zhdr, enum buddy bud)
220{
221 unsigned long handle;
222
223 handle = (unsigned long)zhdr;
224 if (bud != HEADLESS)
225 handle += (bud + zhdr->first_num) & BUDDY_MASK;
226 return handle;
227}
228
229/* Returns the z3fold page where a given handle is stored */
230static struct z3fold_header *handle_to_z3fold_header(unsigned long handle)
231{
232 return (struct z3fold_header *)(handle & PAGE_MASK);
233}
234
zhong jiangf201ebd2017-02-22 15:46:51 -0800235/*
236 * (handle & BUDDY_MASK) < zhdr->first_num is possible in encode_handle
237 * but that doesn't matter. because the masking will result in the
238 * correct buddy number.
239 */
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700240static enum buddy handle_to_buddy(unsigned long handle)
241{
242 struct z3fold_header *zhdr = handle_to_z3fold_header(handle);
243 return (handle - zhdr->first_num) & BUDDY_MASK;
244}
245
Vitaly Woold30561c2017-09-06 16:24:47 -0700246static void __release_z3fold_page(struct z3fold_header *zhdr, bool locked)
247{
248 struct page *page = virt_to_page(zhdr);
249 struct z3fold_pool *pool = zhdr->pool;
250
251 WARN_ON(!list_empty(&zhdr->buddy));
252 set_bit(PAGE_STALE, &page->private);
Vitaly Wool35529352017-10-03 16:15:06 -0700253 clear_bit(NEEDS_COMPACTING, &page->private);
Vitaly Woold30561c2017-09-06 16:24:47 -0700254 spin_lock(&pool->lock);
255 if (!list_empty(&page->lru))
256 list_del(&page->lru);
257 spin_unlock(&pool->lock);
258 if (locked)
259 z3fold_page_unlock(zhdr);
260 spin_lock(&pool->stale_lock);
261 list_add(&zhdr->buddy, &pool->stale);
262 queue_work(pool->release_wq, &pool->work);
263 spin_unlock(&pool->stale_lock);
264}
265
266static void __attribute__((__unused__))
267 release_z3fold_page(struct kref *ref)
268{
269 struct z3fold_header *zhdr = container_of(ref, struct z3fold_header,
270 refcount);
271 __release_z3fold_page(zhdr, false);
272}
273
274static void release_z3fold_page_locked(struct kref *ref)
275{
276 struct z3fold_header *zhdr = container_of(ref, struct z3fold_header,
277 refcount);
278 WARN_ON(z3fold_page_trylock(zhdr));
279 __release_z3fold_page(zhdr, true);
280}
281
282static void release_z3fold_page_locked_list(struct kref *ref)
283{
284 struct z3fold_header *zhdr = container_of(ref, struct z3fold_header,
285 refcount);
286 spin_lock(&zhdr->pool->lock);
287 list_del_init(&zhdr->buddy);
288 spin_unlock(&zhdr->pool->lock);
289
290 WARN_ON(z3fold_page_trylock(zhdr));
291 __release_z3fold_page(zhdr, true);
292}
293
294static void free_pages_work(struct work_struct *w)
295{
296 struct z3fold_pool *pool = container_of(w, struct z3fold_pool, work);
297
298 spin_lock(&pool->stale_lock);
299 while (!list_empty(&pool->stale)) {
300 struct z3fold_header *zhdr = list_first_entry(&pool->stale,
301 struct z3fold_header, buddy);
302 struct page *page = virt_to_page(zhdr);
303
304 list_del(&zhdr->buddy);
305 if (WARN_ON(!test_bit(PAGE_STALE, &page->private)))
306 continue;
Vitaly Woold30561c2017-09-06 16:24:47 -0700307 spin_unlock(&pool->stale_lock);
308 cancel_work_sync(&zhdr->work);
309 free_z3fold_page(page);
310 cond_resched();
311 spin_lock(&pool->stale_lock);
312 }
313 spin_unlock(&pool->stale_lock);
314}
315
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700316/*
317 * Returns the number of free chunks in a z3fold page.
318 * NB: can't be used with HEADLESS pages.
319 */
320static int num_free_chunks(struct z3fold_header *zhdr)
321{
322 int nfree;
323 /*
324 * If there is a middle object, pick up the bigger free space
325 * either before or after it. Otherwise just subtract the number
326 * of chunks occupied by the first and the last objects.
327 */
328 if (zhdr->middle_chunks != 0) {
329 int nfree_before = zhdr->first_chunks ?
Vitaly Woolede93212017-02-24 14:57:17 -0800330 0 : zhdr->start_middle - ZHDR_CHUNKS;
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700331 int nfree_after = zhdr->last_chunks ?
Vitaly Woolede93212017-02-24 14:57:17 -0800332 0 : TOTAL_CHUNKS -
333 (zhdr->start_middle + zhdr->middle_chunks);
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700334 nfree = max(nfree_before, nfree_after);
335 } else
336 nfree = NCHUNKS - zhdr->first_chunks - zhdr->last_chunks;
337 return nfree;
338}
339
Vitaly Woolede93212017-02-24 14:57:17 -0800340static inline void *mchunk_memmove(struct z3fold_header *zhdr,
341 unsigned short dst_chunk)
342{
343 void *beg = zhdr;
344 return memmove(beg + (dst_chunk << CHUNK_SHIFT),
345 beg + (zhdr->start_middle << CHUNK_SHIFT),
346 zhdr->middle_chunks << CHUNK_SHIFT);
347}
348
Vitaly Wool1b096e52017-02-24 14:57:20 -0800349#define BIG_CHUNK_GAP 3
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700350/* Has to be called with lock held */
351static int z3fold_compact_page(struct z3fold_header *zhdr)
352{
353 struct page *page = virt_to_page(zhdr);
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700354
Vitaly Woolede93212017-02-24 14:57:17 -0800355 if (test_bit(MIDDLE_CHUNK_MAPPED, &page->private))
356 return 0; /* can't move middle chunk, it's used */
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700357
Vitaly Woolede93212017-02-24 14:57:17 -0800358 if (zhdr->middle_chunks == 0)
359 return 0; /* nothing to compact */
360
361 if (zhdr->first_chunks == 0 && zhdr->last_chunks == 0) {
362 /* move to the beginning */
363 mchunk_memmove(zhdr, ZHDR_CHUNKS);
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700364 zhdr->first_chunks = zhdr->middle_chunks;
365 zhdr->middle_chunks = 0;
366 zhdr->start_middle = 0;
367 zhdr->first_num++;
Vitaly Wool1b096e52017-02-24 14:57:20 -0800368 return 1;
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700369 }
Vitaly Wool1b096e52017-02-24 14:57:20 -0800370
371 /*
372 * moving data is expensive, so let's only do that if
373 * there's substantial gain (at least BIG_CHUNK_GAP chunks)
374 */
375 if (zhdr->first_chunks != 0 && zhdr->last_chunks == 0 &&
376 zhdr->start_middle - (zhdr->first_chunks + ZHDR_CHUNKS) >=
377 BIG_CHUNK_GAP) {
378 mchunk_memmove(zhdr, zhdr->first_chunks + ZHDR_CHUNKS);
379 zhdr->start_middle = zhdr->first_chunks + ZHDR_CHUNKS;
380 return 1;
381 } else if (zhdr->last_chunks != 0 && zhdr->first_chunks == 0 &&
382 TOTAL_CHUNKS - (zhdr->last_chunks + zhdr->start_middle
383 + zhdr->middle_chunks) >=
384 BIG_CHUNK_GAP) {
385 unsigned short new_start = TOTAL_CHUNKS - zhdr->last_chunks -
386 zhdr->middle_chunks;
387 mchunk_memmove(zhdr, new_start);
388 zhdr->start_middle = new_start;
389 return 1;
390 }
391
392 return 0;
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700393}
394
Vitaly Woold30561c2017-09-06 16:24:47 -0700395static void do_compact_page(struct z3fold_header *zhdr, bool locked)
396{
397 struct z3fold_pool *pool = zhdr->pool;
398 struct page *page;
399 struct list_head *unbuddied;
400 int fchunks;
401
402 page = virt_to_page(zhdr);
403 if (locked)
404 WARN_ON(z3fold_page_trylock(zhdr));
405 else
406 z3fold_page_lock(zhdr);
Vitaly Wool5d03a662017-11-17 15:26:16 -0800407 if (WARN_ON(!test_and_clear_bit(NEEDS_COMPACTING, &page->private))) {
Vitaly Woold30561c2017-09-06 16:24:47 -0700408 z3fold_page_unlock(zhdr);
409 return;
410 }
411 spin_lock(&pool->lock);
412 list_del_init(&zhdr->buddy);
413 spin_unlock(&pool->lock);
414
Vitaly Wool5d03a662017-11-17 15:26:16 -0800415 if (kref_put(&zhdr->refcount, release_z3fold_page_locked)) {
416 atomic64_dec(&pool->pages_nr);
417 return;
418 }
419
Vitaly Woold30561c2017-09-06 16:24:47 -0700420 z3fold_compact_page(zhdr);
421 unbuddied = get_cpu_ptr(pool->unbuddied);
422 fchunks = num_free_chunks(zhdr);
423 if (fchunks < NCHUNKS &&
424 (!zhdr->first_chunks || !zhdr->middle_chunks ||
425 !zhdr->last_chunks)) {
426 /* the page's not completely free and it's unbuddied */
427 spin_lock(&pool->lock);
428 list_add(&zhdr->buddy, &unbuddied[fchunks]);
429 spin_unlock(&pool->lock);
430 zhdr->cpu = smp_processor_id();
431 }
432 put_cpu_ptr(pool->unbuddied);
433 z3fold_page_unlock(zhdr);
434}
435
436static void compact_page_work(struct work_struct *w)
437{
438 struct z3fold_header *zhdr = container_of(w, struct z3fold_header,
439 work);
440
441 do_compact_page(zhdr, false);
442}
443
444
445/*
446 * API Functions
447 */
448
449/**
450 * z3fold_create_pool() - create a new z3fold pool
451 * @name: pool name
452 * @gfp: gfp flags when allocating the z3fold pool structure
453 * @ops: user-defined operations for the z3fold pool
454 *
455 * Return: pointer to the new z3fold pool or NULL if the metadata allocation
456 * failed.
457 */
458static struct z3fold_pool *z3fold_create_pool(const char *name, gfp_t gfp,
459 const struct z3fold_ops *ops)
460{
461 struct z3fold_pool *pool = NULL;
462 int i, cpu;
463
464 pool = kzalloc(sizeof(struct z3fold_pool), gfp);
465 if (!pool)
466 goto out;
467 spin_lock_init(&pool->lock);
468 spin_lock_init(&pool->stale_lock);
469 pool->unbuddied = __alloc_percpu(sizeof(struct list_head)*NCHUNKS, 2);
470 for_each_possible_cpu(cpu) {
471 struct list_head *unbuddied =
472 per_cpu_ptr(pool->unbuddied, cpu);
473 for_each_unbuddied_list(i, 0)
474 INIT_LIST_HEAD(&unbuddied[i]);
475 }
476 INIT_LIST_HEAD(&pool->lru);
477 INIT_LIST_HEAD(&pool->stale);
478 atomic64_set(&pool->pages_nr, 0);
479 pool->name = name;
480 pool->compact_wq = create_singlethread_workqueue(pool->name);
481 if (!pool->compact_wq)
482 goto out;
483 pool->release_wq = create_singlethread_workqueue(pool->name);
484 if (!pool->release_wq)
485 goto out_wq;
486 INIT_WORK(&pool->work, free_pages_work);
487 pool->ops = ops;
488 return pool;
489
490out_wq:
491 destroy_workqueue(pool->compact_wq);
492out:
493 kfree(pool);
494 return NULL;
495}
496
497/**
498 * z3fold_destroy_pool() - destroys an existing z3fold pool
499 * @pool: the z3fold pool to be destroyed
500 *
501 * The pool should be emptied before this function is called.
502 */
503static void z3fold_destroy_pool(struct z3fold_pool *pool)
504{
505 destroy_workqueue(pool->release_wq);
506 destroy_workqueue(pool->compact_wq);
507 kfree(pool);
508}
509
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700510/**
511 * z3fold_alloc() - allocates a region of a given size
512 * @pool: z3fold pool from which to allocate
513 * @size: size in bytes of the desired allocation
514 * @gfp: gfp flags used if the pool needs to grow
515 * @handle: handle of the new allocation
516 *
517 * This function will attempt to find a free region in the pool large enough to
518 * satisfy the allocation request. A search of the unbuddied lists is
519 * performed first. If no suitable free region is found, then a new page is
520 * allocated and added to the pool to satisfy the request.
521 *
522 * gfp should not set __GFP_HIGHMEM as highmem pages cannot be used
523 * as z3fold pool pages.
524 *
525 * Return: 0 if success and handle is set, otherwise -EINVAL if the size or
526 * gfp arguments are invalid or -ENOMEM if the pool was unable to allocate
527 * a new page.
528 */
529static int z3fold_alloc(struct z3fold_pool *pool, size_t size, gfp_t gfp,
530 unsigned long *handle)
531{
532 int chunks = 0, i, freechunks;
533 struct z3fold_header *zhdr = NULL;
Vitaly Woold30561c2017-09-06 16:24:47 -0700534 struct page *page = NULL;
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700535 enum buddy bud;
Vitaly Woold30561c2017-09-06 16:24:47 -0700536 bool can_sleep = (gfp & __GFP_RECLAIM) == __GFP_RECLAIM;
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700537
538 if (!size || (gfp & __GFP_HIGHMEM))
539 return -EINVAL;
540
541 if (size > PAGE_SIZE)
542 return -ENOSPC;
543
544 if (size > PAGE_SIZE - ZHDR_SIZE_ALIGNED - CHUNK_SIZE)
545 bud = HEADLESS;
546 else {
Vitaly Woold30561c2017-09-06 16:24:47 -0700547 struct list_head *unbuddied;
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700548 chunks = size_to_chunks(size);
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700549
Vitaly Woold30561c2017-09-06 16:24:47 -0700550lookup:
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700551 /* First, try to find an unbuddied z3fold page. */
Vitaly Woold30561c2017-09-06 16:24:47 -0700552 unbuddied = get_cpu_ptr(pool->unbuddied);
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700553 for_each_unbuddied_list(i, chunks) {
Vitaly Woold30561c2017-09-06 16:24:47 -0700554 struct list_head *l = &unbuddied[i];
555
556 zhdr = list_first_entry_or_null(READ_ONCE(l),
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700557 struct z3fold_header, buddy);
Vitaly Woold30561c2017-09-06 16:24:47 -0700558
559 if (!zhdr)
Vitaly Wool2f1e5e42017-02-24 14:57:23 -0800560 continue;
Vitaly Woold30561c2017-09-06 16:24:47 -0700561
562 /* Re-check under lock. */
563 spin_lock(&pool->lock);
564 l = &unbuddied[i];
565 if (unlikely(zhdr != list_first_entry(READ_ONCE(l),
566 struct z3fold_header, buddy)) ||
567 !z3fold_page_trylock(zhdr)) {
568 spin_unlock(&pool->lock);
569 put_cpu_ptr(pool->unbuddied);
570 goto lookup;
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700571 }
Vitaly Wool2f1e5e42017-02-24 14:57:23 -0800572 list_del_init(&zhdr->buddy);
Vitaly Woold30561c2017-09-06 16:24:47 -0700573 zhdr->cpu = -1;
Vitaly Wool2f1e5e42017-02-24 14:57:23 -0800574 spin_unlock(&pool->lock);
575
576 page = virt_to_page(zhdr);
Vitaly Woold30561c2017-09-06 16:24:47 -0700577 if (test_bit(NEEDS_COMPACTING, &page->private)) {
578 z3fold_page_unlock(zhdr);
579 zhdr = NULL;
580 put_cpu_ptr(pool->unbuddied);
581 if (can_sleep)
582 cond_resched();
583 goto lookup;
584 }
585
586 /*
587 * this page could not be removed from its unbuddied
588 * list while pool lock was held, and then we've taken
589 * page lock so kref_put could not be called before
590 * we got here, so it's safe to just call kref_get()
591 */
592 kref_get(&zhdr->refcount);
593 break;
594 }
595 put_cpu_ptr(pool->unbuddied);
596
597 if (zhdr) {
Vitaly Wool2f1e5e42017-02-24 14:57:23 -0800598 if (zhdr->first_chunks == 0) {
599 if (zhdr->middle_chunks != 0 &&
600 chunks >= zhdr->start_middle)
601 bud = LAST;
602 else
603 bud = FIRST;
604 } else if (zhdr->last_chunks == 0)
605 bud = LAST;
606 else if (zhdr->middle_chunks == 0)
607 bud = MIDDLE;
608 else {
Vitaly Wool5a27aa82017-02-24 14:57:26 -0800609 if (kref_put(&zhdr->refcount,
Vitaly Woold30561c2017-09-06 16:24:47 -0700610 release_z3fold_page_locked))
Vitaly Wool5a27aa82017-02-24 14:57:26 -0800611 atomic64_dec(&pool->pages_nr);
Vitaly Woold30561c2017-09-06 16:24:47 -0700612 else
613 z3fold_page_unlock(zhdr);
Vitaly Wool2f1e5e42017-02-24 14:57:23 -0800614 pr_err("No free chunks in unbuddied\n");
615 WARN_ON(1);
Vitaly Woold30561c2017-09-06 16:24:47 -0700616 goto lookup;
Vitaly Wool2f1e5e42017-02-24 14:57:23 -0800617 }
618 goto found;
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700619 }
620 bud = FIRST;
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700621 }
622
Vitaly Woold30561c2017-09-06 16:24:47 -0700623 spin_lock(&pool->stale_lock);
624 zhdr = list_first_entry_or_null(&pool->stale,
625 struct z3fold_header, buddy);
626 /*
627 * Before allocating a page, let's see if we can take one from the
628 * stale pages list. cancel_work_sync() can sleep so we must make
629 * sure it won't be called in case we're in atomic context.
630 */
Vitaly Wool35529352017-10-03 16:15:06 -0700631 if (zhdr && (can_sleep || !work_pending(&zhdr->work))) {
Vitaly Woold30561c2017-09-06 16:24:47 -0700632 list_del(&zhdr->buddy);
Vitaly Woold30561c2017-09-06 16:24:47 -0700633 spin_unlock(&pool->stale_lock);
634 if (can_sleep)
635 cancel_work_sync(&zhdr->work);
636 page = virt_to_page(zhdr);
637 } else {
638 spin_unlock(&pool->stale_lock);
639 page = alloc_page(gfp);
640 }
641
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700642 if (!page)
643 return -ENOMEM;
Vitaly Wool2f1e5e42017-02-24 14:57:23 -0800644
Vitaly Wool12d59ae2017-02-24 14:57:15 -0800645 atomic64_inc(&pool->pages_nr);
Vitaly Woold30561c2017-09-06 16:24:47 -0700646 zhdr = init_z3fold_page(page, pool);
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700647
648 if (bud == HEADLESS) {
649 set_bit(PAGE_HEADLESS, &page->private);
650 goto headless;
651 }
Vitaly Wool2f1e5e42017-02-24 14:57:23 -0800652 z3fold_page_lock(zhdr);
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700653
654found:
655 if (bud == FIRST)
656 zhdr->first_chunks = chunks;
657 else if (bud == LAST)
658 zhdr->last_chunks = chunks;
659 else {
660 zhdr->middle_chunks = chunks;
Vitaly Woolede93212017-02-24 14:57:17 -0800661 zhdr->start_middle = zhdr->first_chunks + ZHDR_CHUNKS;
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700662 }
663
664 if (zhdr->first_chunks == 0 || zhdr->last_chunks == 0 ||
665 zhdr->middle_chunks == 0) {
Vitaly Woold30561c2017-09-06 16:24:47 -0700666 struct list_head *unbuddied = get_cpu_ptr(pool->unbuddied);
667
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700668 /* Add to unbuddied list */
669 freechunks = num_free_chunks(zhdr);
Vitaly Woold30561c2017-09-06 16:24:47 -0700670 spin_lock(&pool->lock);
671 list_add(&zhdr->buddy, &unbuddied[freechunks]);
672 spin_unlock(&pool->lock);
673 zhdr->cpu = smp_processor_id();
674 put_cpu_ptr(pool->unbuddied);
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700675 }
676
677headless:
Vitaly Woold30561c2017-09-06 16:24:47 -0700678 spin_lock(&pool->lock);
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700679 /* Add/move z3fold page to beginning of LRU */
680 if (!list_empty(&page->lru))
681 list_del(&page->lru);
682
683 list_add(&page->lru, &pool->lru);
684
685 *handle = encode_handle(zhdr, bud);
686 spin_unlock(&pool->lock);
Vitaly Wool2f1e5e42017-02-24 14:57:23 -0800687 if (bud != HEADLESS)
688 z3fold_page_unlock(zhdr);
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700689
690 return 0;
691}
692
693/**
694 * z3fold_free() - frees the allocation associated with the given handle
695 * @pool: pool in which the allocation resided
696 * @handle: handle associated with the allocation returned by z3fold_alloc()
697 *
698 * In the case that the z3fold page in which the allocation resides is under
699 * reclaim, as indicated by the PG_reclaim flag being set, this function
700 * only sets the first|last_chunks to 0. The page is actually freed
701 * once both buddies are evicted (see z3fold_reclaim_page() below).
702 */
703static void z3fold_free(struct z3fold_pool *pool, unsigned long handle)
704{
705 struct z3fold_header *zhdr;
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700706 struct page *page;
707 enum buddy bud;
708
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700709 zhdr = handle_to_z3fold_header(handle);
710 page = virt_to_page(zhdr);
711
712 if (test_bit(PAGE_HEADLESS, &page->private)) {
713 /* HEADLESS page stored */
714 bud = HEADLESS;
715 } else {
Vitaly Wool2f1e5e42017-02-24 14:57:23 -0800716 z3fold_page_lock(zhdr);
Vitaly Wool43afc192016-06-03 14:55:47 -0700717 bud = handle_to_buddy(handle);
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700718
719 switch (bud) {
720 case FIRST:
721 zhdr->first_chunks = 0;
722 break;
723 case MIDDLE:
724 zhdr->middle_chunks = 0;
725 zhdr->start_middle = 0;
726 break;
727 case LAST:
728 zhdr->last_chunks = 0;
729 break;
730 default:
731 pr_err("%s: unknown bud %d\n", __func__, bud);
732 WARN_ON(1);
Vitaly Wool2f1e5e42017-02-24 14:57:23 -0800733 z3fold_page_unlock(zhdr);
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700734 return;
735 }
736 }
737
Vitaly Wool5a27aa82017-02-24 14:57:26 -0800738 if (bud == HEADLESS) {
Vitaly Wool2f1e5e42017-02-24 14:57:23 -0800739 spin_lock(&pool->lock);
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700740 list_del(&page->lru);
Vitaly Wool2f1e5e42017-02-24 14:57:23 -0800741 spin_unlock(&pool->lock);
Vitaly Wool5a27aa82017-02-24 14:57:26 -0800742 free_z3fold_page(page);
Vitaly Wool12d59ae2017-02-24 14:57:15 -0800743 atomic64_dec(&pool->pages_nr);
Vitaly Woold30561c2017-09-06 16:24:47 -0700744 return;
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700745 }
746
Vitaly Woold30561c2017-09-06 16:24:47 -0700747 if (kref_put(&zhdr->refcount, release_z3fold_page_locked_list)) {
748 atomic64_dec(&pool->pages_nr);
749 return;
750 }
751 if (test_and_set_bit(NEEDS_COMPACTING, &page->private)) {
752 z3fold_page_unlock(zhdr);
753 return;
754 }
755 if (zhdr->cpu < 0 || !cpu_online(zhdr->cpu)) {
756 spin_lock(&pool->lock);
757 list_del_init(&zhdr->buddy);
758 spin_unlock(&pool->lock);
759 zhdr->cpu = -1;
Vitaly Wool5d03a662017-11-17 15:26:16 -0800760 kref_get(&zhdr->refcount);
Vitaly Woold30561c2017-09-06 16:24:47 -0700761 do_compact_page(zhdr, true);
762 return;
763 }
Vitaly Wool5d03a662017-11-17 15:26:16 -0800764 kref_get(&zhdr->refcount);
Vitaly Woold30561c2017-09-06 16:24:47 -0700765 queue_work_on(zhdr->cpu, pool->compact_wq, &zhdr->work);
766 z3fold_page_unlock(zhdr);
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700767}
768
769/**
770 * z3fold_reclaim_page() - evicts allocations from a pool page and frees it
771 * @pool: pool from which a page will attempt to be evicted
772 * @retires: number of pages on the LRU list for which eviction will
773 * be attempted before failing
774 *
775 * z3fold reclaim is different from normal system reclaim in that it is done
776 * from the bottom, up. This is because only the bottom layer, z3fold, has
777 * information on how the allocations are organized within each z3fold page.
778 * This has the potential to create interesting locking situations between
779 * z3fold and the user, however.
780 *
781 * To avoid these, this is how z3fold_reclaim_page() should be called:
782
783 * The user detects a page should be reclaimed and calls z3fold_reclaim_page().
784 * z3fold_reclaim_page() will remove a z3fold page from the pool LRU list and
785 * call the user-defined eviction handler with the pool and handle as
786 * arguments.
787 *
788 * If the handle can not be evicted, the eviction handler should return
789 * non-zero. z3fold_reclaim_page() will add the z3fold page back to the
790 * appropriate list and try the next z3fold page on the LRU up to
791 * a user defined number of retries.
792 *
793 * If the handle is successfully evicted, the eviction handler should
794 * return 0 _and_ should have called z3fold_free() on the handle. z3fold_free()
795 * contains logic to delay freeing the page if the page is under reclaim,
796 * as indicated by the setting of the PG_reclaim flag on the underlying page.
797 *
798 * If all buddies in the z3fold page are successfully evicted, then the
799 * z3fold page can be freed.
800 *
801 * Returns: 0 if page is successfully freed, otherwise -EINVAL if there are
802 * no pages to evict or an eviction handler is not registered, -EAGAIN if
803 * the retry limit was hit.
804 */
805static int z3fold_reclaim_page(struct z3fold_pool *pool, unsigned int retries)
806{
Vitaly Woold30561c2017-09-06 16:24:47 -0700807 int i, ret = 0;
808 struct z3fold_header *zhdr = NULL;
809 struct page *page = NULL;
810 struct list_head *pos;
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700811 unsigned long first_handle = 0, middle_handle = 0, last_handle = 0;
812
813 spin_lock(&pool->lock);
Vitaly Wool2f1e5e42017-02-24 14:57:23 -0800814 if (!pool->ops || !pool->ops->evict || retries == 0) {
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700815 spin_unlock(&pool->lock);
816 return -EINVAL;
817 }
818 for (i = 0; i < retries; i++) {
Vitaly Wool2f1e5e42017-02-24 14:57:23 -0800819 if (list_empty(&pool->lru)) {
820 spin_unlock(&pool->lock);
821 return -EINVAL;
822 }
Vitaly Woold30561c2017-09-06 16:24:47 -0700823 list_for_each_prev(pos, &pool->lru) {
824 page = list_entry(pos, struct page, lru);
825 if (test_bit(PAGE_HEADLESS, &page->private))
826 /* candidate found */
827 break;
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700828
Vitaly Woold30561c2017-09-06 16:24:47 -0700829 zhdr = page_address(page);
830 if (!z3fold_page_trylock(zhdr))
831 continue; /* can't evict at this point */
Vitaly Wool5a27aa82017-02-24 14:57:26 -0800832 kref_get(&zhdr->refcount);
Vitaly Woold30561c2017-09-06 16:24:47 -0700833 list_del_init(&zhdr->buddy);
834 zhdr->cpu = -1;
835 }
836
837 list_del_init(&page->lru);
838 spin_unlock(&pool->lock);
839
840 if (!test_bit(PAGE_HEADLESS, &page->private)) {
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700841 /*
842 * We need encode the handles before unlocking, since
843 * we can race with free that will set
844 * (first|last)_chunks to 0
845 */
846 first_handle = 0;
847 last_handle = 0;
848 middle_handle = 0;
849 if (zhdr->first_chunks)
850 first_handle = encode_handle(zhdr, FIRST);
851 if (zhdr->middle_chunks)
852 middle_handle = encode_handle(zhdr, MIDDLE);
853 if (zhdr->last_chunks)
854 last_handle = encode_handle(zhdr, LAST);
Vitaly Woold30561c2017-09-06 16:24:47 -0700855 /*
856 * it's safe to unlock here because we hold a
857 * reference to this page
858 */
Vitaly Wool2f1e5e42017-02-24 14:57:23 -0800859 z3fold_page_unlock(zhdr);
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700860 } else {
861 first_handle = encode_handle(zhdr, HEADLESS);
862 last_handle = middle_handle = 0;
863 }
864
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700865 /* Issue the eviction callback(s) */
866 if (middle_handle) {
867 ret = pool->ops->evict(pool, middle_handle);
868 if (ret)
869 goto next;
870 }
871 if (first_handle) {
872 ret = pool->ops->evict(pool, first_handle);
873 if (ret)
874 goto next;
875 }
876 if (last_handle) {
877 ret = pool->ops->evict(pool, last_handle);
878 if (ret)
879 goto next;
880 }
881next:
Vitaly Woold5567c92017-10-03 16:14:47 -0700882 spin_lock(&pool->lock);
Vitaly Wool5a27aa82017-02-24 14:57:26 -0800883 if (test_bit(PAGE_HEADLESS, &page->private)) {
884 if (ret == 0) {
Vitaly Woold5567c92017-10-03 16:14:47 -0700885 spin_unlock(&pool->lock);
Vitaly Wool5a27aa82017-02-24 14:57:26 -0800886 free_z3fold_page(page);
887 return 0;
Vitaly Wool5a27aa82017-02-24 14:57:26 -0800888 }
Vitaly Woold30561c2017-09-06 16:24:47 -0700889 } else if (kref_put(&zhdr->refcount, release_z3fold_page)) {
890 atomic64_dec(&pool->pages_nr);
Vitaly Woold5567c92017-10-03 16:14:47 -0700891 spin_unlock(&pool->lock);
Vitaly Woold30561c2017-09-06 16:24:47 -0700892 return 0;
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700893 }
894
Vitaly Wool5a27aa82017-02-24 14:57:26 -0800895 /*
896 * Add to the beginning of LRU.
897 * Pool lock has to be kept here to ensure the page has
898 * not already been released
899 */
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700900 list_add(&page->lru, &pool->lru);
901 }
902 spin_unlock(&pool->lock);
903 return -EAGAIN;
904}
905
906/**
907 * z3fold_map() - maps the allocation associated with the given handle
908 * @pool: pool in which the allocation resides
909 * @handle: handle associated with the allocation to be mapped
910 *
911 * Extracts the buddy number from handle and constructs the pointer to the
912 * correct starting chunk within the page.
913 *
914 * Returns: a pointer to the mapped allocation
915 */
916static void *z3fold_map(struct z3fold_pool *pool, unsigned long handle)
917{
918 struct z3fold_header *zhdr;
919 struct page *page;
920 void *addr;
921 enum buddy buddy;
922
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700923 zhdr = handle_to_z3fold_header(handle);
924 addr = zhdr;
925 page = virt_to_page(zhdr);
926
927 if (test_bit(PAGE_HEADLESS, &page->private))
928 goto out;
929
Vitaly Wool2f1e5e42017-02-24 14:57:23 -0800930 z3fold_page_lock(zhdr);
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700931 buddy = handle_to_buddy(handle);
932 switch (buddy) {
933 case FIRST:
934 addr += ZHDR_SIZE_ALIGNED;
935 break;
936 case MIDDLE:
937 addr += zhdr->start_middle << CHUNK_SHIFT;
938 set_bit(MIDDLE_CHUNK_MAPPED, &page->private);
939 break;
940 case LAST:
941 addr += PAGE_SIZE - (zhdr->last_chunks << CHUNK_SHIFT);
942 break;
943 default:
944 pr_err("unknown buddy id %d\n", buddy);
945 WARN_ON(1);
946 addr = NULL;
947 break;
948 }
Vitaly Wool2f1e5e42017-02-24 14:57:23 -0800949
950 z3fold_page_unlock(zhdr);
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700951out:
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700952 return addr;
953}
954
955/**
956 * z3fold_unmap() - unmaps the allocation associated with the given handle
957 * @pool: pool in which the allocation resides
958 * @handle: handle associated with the allocation to be unmapped
959 */
960static void z3fold_unmap(struct z3fold_pool *pool, unsigned long handle)
961{
962 struct z3fold_header *zhdr;
963 struct page *page;
964 enum buddy buddy;
965
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700966 zhdr = handle_to_z3fold_header(handle);
967 page = virt_to_page(zhdr);
968
Vitaly Wool2f1e5e42017-02-24 14:57:23 -0800969 if (test_bit(PAGE_HEADLESS, &page->private))
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700970 return;
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700971
Vitaly Wool2f1e5e42017-02-24 14:57:23 -0800972 z3fold_page_lock(zhdr);
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700973 buddy = handle_to_buddy(handle);
974 if (buddy == MIDDLE)
975 clear_bit(MIDDLE_CHUNK_MAPPED, &page->private);
Vitaly Wool2f1e5e42017-02-24 14:57:23 -0800976 z3fold_page_unlock(zhdr);
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700977}
978
979/**
980 * z3fold_get_pool_size() - gets the z3fold pool size in pages
981 * @pool: pool whose size is being queried
982 *
Vitaly Wool12d59ae2017-02-24 14:57:15 -0800983 * Returns: size in pages of the given pool.
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700984 */
985static u64 z3fold_get_pool_size(struct z3fold_pool *pool)
986{
Vitaly Wool12d59ae2017-02-24 14:57:15 -0800987 return atomic64_read(&pool->pages_nr);
Vitaly Wool9a001fc2016-05-20 16:58:30 -0700988}
989
990/*****************
991 * zpool
992 ****************/
993
994static int z3fold_zpool_evict(struct z3fold_pool *pool, unsigned long handle)
995{
996 if (pool->zpool && pool->zpool_ops && pool->zpool_ops->evict)
997 return pool->zpool_ops->evict(pool->zpool, handle);
998 else
999 return -ENOENT;
1000}
1001
1002static const struct z3fold_ops z3fold_zpool_ops = {
1003 .evict = z3fold_zpool_evict
1004};
1005
1006static void *z3fold_zpool_create(const char *name, gfp_t gfp,
1007 const struct zpool_ops *zpool_ops,
1008 struct zpool *zpool)
1009{
1010 struct z3fold_pool *pool;
1011
Vitaly Woold30561c2017-09-06 16:24:47 -07001012 pool = z3fold_create_pool(name, gfp,
1013 zpool_ops ? &z3fold_zpool_ops : NULL);
Vitaly Wool9a001fc2016-05-20 16:58:30 -07001014 if (pool) {
1015 pool->zpool = zpool;
1016 pool->zpool_ops = zpool_ops;
1017 }
1018 return pool;
1019}
1020
1021static void z3fold_zpool_destroy(void *pool)
1022{
1023 z3fold_destroy_pool(pool);
1024}
1025
1026static int z3fold_zpool_malloc(void *pool, size_t size, gfp_t gfp,
1027 unsigned long *handle)
1028{
1029 return z3fold_alloc(pool, size, gfp, handle);
1030}
1031static void z3fold_zpool_free(void *pool, unsigned long handle)
1032{
1033 z3fold_free(pool, handle);
1034}
1035
1036static int z3fold_zpool_shrink(void *pool, unsigned int pages,
1037 unsigned int *reclaimed)
1038{
1039 unsigned int total = 0;
1040 int ret = -EINVAL;
1041
1042 while (total < pages) {
1043 ret = z3fold_reclaim_page(pool, 8);
1044 if (ret < 0)
1045 break;
1046 total++;
1047 }
1048
1049 if (reclaimed)
1050 *reclaimed = total;
1051
1052 return ret;
1053}
1054
1055static void *z3fold_zpool_map(void *pool, unsigned long handle,
1056 enum zpool_mapmode mm)
1057{
1058 return z3fold_map(pool, handle);
1059}
1060static void z3fold_zpool_unmap(void *pool, unsigned long handle)
1061{
1062 z3fold_unmap(pool, handle);
1063}
1064
1065static u64 z3fold_zpool_total_size(void *pool)
1066{
1067 return z3fold_get_pool_size(pool) * PAGE_SIZE;
1068}
1069
1070static struct zpool_driver z3fold_zpool_driver = {
1071 .type = "z3fold",
1072 .owner = THIS_MODULE,
1073 .create = z3fold_zpool_create,
1074 .destroy = z3fold_zpool_destroy,
1075 .malloc = z3fold_zpool_malloc,
1076 .free = z3fold_zpool_free,
1077 .shrink = z3fold_zpool_shrink,
1078 .map = z3fold_zpool_map,
1079 .unmap = z3fold_zpool_unmap,
1080 .total_size = z3fold_zpool_total_size,
1081};
1082
1083MODULE_ALIAS("zpool-z3fold");
1084
1085static int __init init_z3fold(void)
1086{
Vitaly Woolede93212017-02-24 14:57:17 -08001087 /* Make sure the z3fold header is not larger than the page size */
1088 BUILD_BUG_ON(ZHDR_SIZE_ALIGNED > PAGE_SIZE);
Vitaly Wool9a001fc2016-05-20 16:58:30 -07001089 zpool_register_driver(&z3fold_zpool_driver);
1090
1091 return 0;
1092}
1093
1094static void __exit exit_z3fold(void)
1095{
1096 zpool_unregister_driver(&z3fold_zpool_driver);
1097}
1098
1099module_init(init_z3fold);
1100module_exit(exit_z3fold);
1101
1102MODULE_LICENSE("GPL");
1103MODULE_AUTHOR("Vitaly Wool <vitalywool@gmail.com>");
1104MODULE_DESCRIPTION("3-Fold Allocator for Compressed Pages");