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1/*
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>
26#include <linux/list.h>
27#include <linux/mm.h>
28#include <linux/module.h>
29#include <linux/preempt.h>
30#include <linux/slab.h>
31#include <linux/spinlock.h>
32#include <linux/zpool.h>
33
34/*****************
35 * Structures
36*****************/
37/*
38 * NCHUNKS_ORDER determines the internal allocation granularity, effectively
39 * adjusting internal fragmentation. It also determines the number of
40 * freelists maintained in each pool. NCHUNKS_ORDER of 6 means that the
41 * allocation granularity will be in chunks of size PAGE_SIZE/64. As one chunk
42 * in allocated page is occupied by z3fold header, NCHUNKS will be calculated
43 * to 63 which shows the max number of free chunks in z3fold page, also there
44 * will be 63 freelists per pool.
45 */
46#define NCHUNKS_ORDER 6
47
48#define CHUNK_SHIFT (PAGE_SHIFT - NCHUNKS_ORDER)
49#define CHUNK_SIZE (1 << CHUNK_SHIFT)
50#define ZHDR_SIZE_ALIGNED CHUNK_SIZE
51#define NCHUNKS ((PAGE_SIZE - ZHDR_SIZE_ALIGNED) >> CHUNK_SHIFT)
52
53#define BUDDY_MASK ((1 << NCHUNKS_ORDER) - 1)
54
55struct z3fold_pool;
56struct z3fold_ops {
57 int (*evict)(struct z3fold_pool *pool, unsigned long handle);
58};
59
60/**
61 * struct z3fold_pool - stores metadata for each z3fold pool
62 * @lock: protects all pool fields and first|last_chunk fields of any
63 * z3fold page in the pool
64 * @unbuddied: array of lists tracking z3fold pages that contain 2- buddies;
65 * the lists each z3fold page is added to depends on the size of
66 * its free region.
67 * @buddied: list tracking the z3fold pages that contain 3 buddies;
68 * these z3fold pages are full
69 * @lru: list tracking the z3fold pages in LRU order by most recently
70 * added buddy.
71 * @pages_nr: number of z3fold pages in the pool.
72 * @ops: pointer to a structure of user defined operations specified at
73 * pool creation time.
74 *
75 * This structure is allocated at pool creation time and maintains metadata
76 * pertaining to a particular z3fold pool.
77 */
78struct z3fold_pool {
79 spinlock_t lock;
80 struct list_head unbuddied[NCHUNKS];
81 struct list_head buddied;
82 struct list_head lru;
83 u64 pages_nr;
84 const struct z3fold_ops *ops;
85 struct zpool *zpool;
86 const struct zpool_ops *zpool_ops;
87};
88
89enum buddy {
90 HEADLESS = 0,
91 FIRST,
92 MIDDLE,
93 LAST,
94 BUDDIES_MAX
95};
96
97/*
98 * struct z3fold_header - z3fold page metadata occupying the first chunk of each
99 * z3fold page, except for HEADLESS pages
100 * @buddy: links the z3fold page into the relevant list in the pool
101 * @first_chunks: the size of the first buddy in chunks, 0 if free
102 * @middle_chunks: the size of the middle buddy in chunks, 0 if free
103 * @last_chunks: the size of the last buddy in chunks, 0 if free
104 * @first_num: the starting number (for the first handle)
105 */
106struct z3fold_header {
107 struct list_head buddy;
108 unsigned short first_chunks;
109 unsigned short middle_chunks;
110 unsigned short last_chunks;
111 unsigned short start_middle;
112 unsigned short first_num:NCHUNKS_ORDER;
113};
114
115/*
116 * Internal z3fold page flags
117 */
118enum z3fold_page_flags {
119 UNDER_RECLAIM = 0,
120 PAGE_HEADLESS,
121 MIDDLE_CHUNK_MAPPED,
122};
123
124/*****************
125 * Helpers
126*****************/
127
128/* Converts an allocation size in bytes to size in z3fold chunks */
129static int size_to_chunks(size_t size)
130{
131 return (size + CHUNK_SIZE - 1) >> CHUNK_SHIFT;
132}
133
134#define for_each_unbuddied_list(_iter, _begin) \
135 for ((_iter) = (_begin); (_iter) < NCHUNKS; (_iter)++)
136
137/* Initializes the z3fold header of a newly allocated z3fold page */
138static struct z3fold_header *init_z3fold_page(struct page *page)
139{
140 struct z3fold_header *zhdr = page_address(page);
141
142 INIT_LIST_HEAD(&page->lru);
143 clear_bit(UNDER_RECLAIM, &page->private);
144 clear_bit(PAGE_HEADLESS, &page->private);
145 clear_bit(MIDDLE_CHUNK_MAPPED, &page->private);
146
147 zhdr->first_chunks = 0;
148 zhdr->middle_chunks = 0;
149 zhdr->last_chunks = 0;
150 zhdr->first_num = 0;
151 zhdr->start_middle = 0;
152 INIT_LIST_HEAD(&zhdr->buddy);
153 return zhdr;
154}
155
156/* Resets the struct page fields and frees the page */
157static void free_z3fold_page(struct z3fold_header *zhdr)
158{
159 __free_page(virt_to_page(zhdr));
160}
161
162/*
163 * Encodes the handle of a particular buddy within a z3fold page
164 * Pool lock should be held as this function accesses first_num
165 */
166static unsigned long encode_handle(struct z3fold_header *zhdr, enum buddy bud)
167{
168 unsigned long handle;
169
170 handle = (unsigned long)zhdr;
171 if (bud != HEADLESS)
172 handle += (bud + zhdr->first_num) & BUDDY_MASK;
173 return handle;
174}
175
176/* Returns the z3fold page where a given handle is stored */
177static struct z3fold_header *handle_to_z3fold_header(unsigned long handle)
178{
179 return (struct z3fold_header *)(handle & PAGE_MASK);
180}
181
182/* Returns buddy number */
183static enum buddy handle_to_buddy(unsigned long handle)
184{
185 struct z3fold_header *zhdr = handle_to_z3fold_header(handle);
186 return (handle - zhdr->first_num) & BUDDY_MASK;
187}
188
189/*
190 * Returns the number of free chunks in a z3fold page.
191 * NB: can't be used with HEADLESS pages.
192 */
193static int num_free_chunks(struct z3fold_header *zhdr)
194{
195 int nfree;
196 /*
197 * If there is a middle object, pick up the bigger free space
198 * either before or after it. Otherwise just subtract the number
199 * of chunks occupied by the first and the last objects.
200 */
201 if (zhdr->middle_chunks != 0) {
202 int nfree_before = zhdr->first_chunks ?
203 0 : zhdr->start_middle - 1;
204 int nfree_after = zhdr->last_chunks ?
205 0 : NCHUNKS - zhdr->start_middle - zhdr->middle_chunks;
206 nfree = max(nfree_before, nfree_after);
207 } else
208 nfree = NCHUNKS - zhdr->first_chunks - zhdr->last_chunks;
209 return nfree;
210}
211
212/*****************
213 * API Functions
214*****************/
215/**
216 * z3fold_create_pool() - create a new z3fold pool
217 * @gfp: gfp flags when allocating the z3fold pool structure
218 * @ops: user-defined operations for the z3fold pool
219 *
220 * Return: pointer to the new z3fold pool or NULL if the metadata allocation
221 * failed.
222 */
223static struct z3fold_pool *z3fold_create_pool(gfp_t gfp,
224 const struct z3fold_ops *ops)
225{
226 struct z3fold_pool *pool;
227 int i;
228
229 pool = kzalloc(sizeof(struct z3fold_pool), gfp);
230 if (!pool)
231 return NULL;
232 spin_lock_init(&pool->lock);
233 for_each_unbuddied_list(i, 0)
234 INIT_LIST_HEAD(&pool->unbuddied[i]);
235 INIT_LIST_HEAD(&pool->buddied);
236 INIT_LIST_HEAD(&pool->lru);
237 pool->pages_nr = 0;
238 pool->ops = ops;
239 return pool;
240}
241
242/**
243 * z3fold_destroy_pool() - destroys an existing z3fold pool
244 * @pool: the z3fold pool to be destroyed
245 *
246 * The pool should be emptied before this function is called.
247 */
248static void z3fold_destroy_pool(struct z3fold_pool *pool)
249{
250 kfree(pool);
251}
252
253/* Has to be called with lock held */
254static int z3fold_compact_page(struct z3fold_header *zhdr)
255{
256 struct page *page = virt_to_page(zhdr);
257 void *beg = zhdr;
258
259
260 if (!test_bit(MIDDLE_CHUNK_MAPPED, &page->private) &&
261 zhdr->middle_chunks != 0 &&
262 zhdr->first_chunks == 0 && zhdr->last_chunks == 0) {
263 memmove(beg + ZHDR_SIZE_ALIGNED,
264 beg + (zhdr->start_middle << CHUNK_SHIFT),
265 zhdr->middle_chunks << CHUNK_SHIFT);
266 zhdr->first_chunks = zhdr->middle_chunks;
267 zhdr->middle_chunks = 0;
268 zhdr->start_middle = 0;
269 zhdr->first_num++;
270 return 1;
271 }
272 return 0;
273}
274
275/**
276 * z3fold_alloc() - allocates a region of a given size
277 * @pool: z3fold pool from which to allocate
278 * @size: size in bytes of the desired allocation
279 * @gfp: gfp flags used if the pool needs to grow
280 * @handle: handle of the new allocation
281 *
282 * This function will attempt to find a free region in the pool large enough to
283 * satisfy the allocation request. A search of the unbuddied lists is
284 * performed first. If no suitable free region is found, then a new page is
285 * allocated and added to the pool to satisfy the request.
286 *
287 * gfp should not set __GFP_HIGHMEM as highmem pages cannot be used
288 * as z3fold pool pages.
289 *
290 * Return: 0 if success and handle is set, otherwise -EINVAL if the size or
291 * gfp arguments are invalid or -ENOMEM if the pool was unable to allocate
292 * a new page.
293 */
294static int z3fold_alloc(struct z3fold_pool *pool, size_t size, gfp_t gfp,
295 unsigned long *handle)
296{
297 int chunks = 0, i, freechunks;
298 struct z3fold_header *zhdr = NULL;
299 enum buddy bud;
300 struct page *page;
301
302 if (!size || (gfp & __GFP_HIGHMEM))
303 return -EINVAL;
304
305 if (size > PAGE_SIZE)
306 return -ENOSPC;
307
308 if (size > PAGE_SIZE - ZHDR_SIZE_ALIGNED - CHUNK_SIZE)
309 bud = HEADLESS;
310 else {
311 chunks = size_to_chunks(size);
312 spin_lock(&pool->lock);
313
314 /* First, try to find an unbuddied z3fold page. */
315 zhdr = NULL;
316 for_each_unbuddied_list(i, chunks) {
317 if (!list_empty(&pool->unbuddied[i])) {
318 zhdr = list_first_entry(&pool->unbuddied[i],
319 struct z3fold_header, buddy);
320 page = virt_to_page(zhdr);
321 if (zhdr->first_chunks == 0) {
322 if (zhdr->middle_chunks != 0 &&
323 chunks >= zhdr->start_middle)
324 bud = LAST;
325 else
326 bud = FIRST;
327 } else if (zhdr->last_chunks == 0)
328 bud = LAST;
329 else if (zhdr->middle_chunks == 0)
330 bud = MIDDLE;
331 else {
332 pr_err("No free chunks in unbuddied\n");
333 WARN_ON(1);
334 continue;
335 }
336 list_del(&zhdr->buddy);
337 goto found;
338 }
339 }
340 bud = FIRST;
341 spin_unlock(&pool->lock);
342 }
343
344 /* Couldn't find unbuddied z3fold page, create new one */
345 page = alloc_page(gfp);
346 if (!page)
347 return -ENOMEM;
348 spin_lock(&pool->lock);
349 pool->pages_nr++;
350 zhdr = init_z3fold_page(page);
351
352 if (bud == HEADLESS) {
353 set_bit(PAGE_HEADLESS, &page->private);
354 goto headless;
355 }
356
357found:
358 if (bud == FIRST)
359 zhdr->first_chunks = chunks;
360 else if (bud == LAST)
361 zhdr->last_chunks = chunks;
362 else {
363 zhdr->middle_chunks = chunks;
364 zhdr->start_middle = zhdr->first_chunks + 1;
365 }
366
367 if (zhdr->first_chunks == 0 || zhdr->last_chunks == 0 ||
368 zhdr->middle_chunks == 0) {
369 /* Add to unbuddied list */
370 freechunks = num_free_chunks(zhdr);
371 list_add(&zhdr->buddy, &pool->unbuddied[freechunks]);
372 } else {
373 /* Add to buddied list */
374 list_add(&zhdr->buddy, &pool->buddied);
375 }
376
377headless:
378 /* Add/move z3fold page to beginning of LRU */
379 if (!list_empty(&page->lru))
380 list_del(&page->lru);
381
382 list_add(&page->lru, &pool->lru);
383
384 *handle = encode_handle(zhdr, bud);
385 spin_unlock(&pool->lock);
386
387 return 0;
388}
389
390/**
391 * z3fold_free() - frees the allocation associated with the given handle
392 * @pool: pool in which the allocation resided
393 * @handle: handle associated with the allocation returned by z3fold_alloc()
394 *
395 * In the case that the z3fold page in which the allocation resides is under
396 * reclaim, as indicated by the PG_reclaim flag being set, this function
397 * only sets the first|last_chunks to 0. The page is actually freed
398 * once both buddies are evicted (see z3fold_reclaim_page() below).
399 */
400static void z3fold_free(struct z3fold_pool *pool, unsigned long handle)
401{
402 struct z3fold_header *zhdr;
403 int freechunks;
404 struct page *page;
405 enum buddy bud;
406
407 spin_lock(&pool->lock);
408 zhdr = handle_to_z3fold_header(handle);
409 page = virt_to_page(zhdr);
410
411 if (test_bit(PAGE_HEADLESS, &page->private)) {
412 /* HEADLESS page stored */
413 bud = HEADLESS;
414 } else {
415 bud = handle_to_buddy(handle);
416
417 switch (bud) {
418 case FIRST:
419 zhdr->first_chunks = 0;
420 break;
421 case MIDDLE:
422 zhdr->middle_chunks = 0;
423 zhdr->start_middle = 0;
424 break;
425 case LAST:
426 zhdr->last_chunks = 0;
427 break;
428 default:
429 pr_err("%s: unknown bud %d\n", __func__, bud);
430 WARN_ON(1);
431 spin_unlock(&pool->lock);
432 return;
433 }
434 }
435
436 if (test_bit(UNDER_RECLAIM, &page->private)) {
437 /* z3fold page is under reclaim, reclaim will free */
438 spin_unlock(&pool->lock);
439 return;
440 }
441
442 if (bud != HEADLESS) {
443 /* Remove from existing buddy list */
444 list_del(&zhdr->buddy);
445 }
446
447 if (bud == HEADLESS ||
448 (zhdr->first_chunks == 0 && zhdr->middle_chunks == 0 &&
449 zhdr->last_chunks == 0)) {
450 /* z3fold page is empty, free */
451 list_del(&page->lru);
452 clear_bit(PAGE_HEADLESS, &page->private);
453 free_z3fold_page(zhdr);
454 pool->pages_nr--;
455 } else {
456 z3fold_compact_page(zhdr);
457 /* Add to the unbuddied list */
458 freechunks = num_free_chunks(zhdr);
459 list_add(&zhdr->buddy, &pool->unbuddied[freechunks]);
460 }
461
462 spin_unlock(&pool->lock);
463}
464
465/**
466 * z3fold_reclaim_page() - evicts allocations from a pool page and frees it
467 * @pool: pool from which a page will attempt to be evicted
468 * @retires: number of pages on the LRU list for which eviction will
469 * be attempted before failing
470 *
471 * z3fold reclaim is different from normal system reclaim in that it is done
472 * from the bottom, up. This is because only the bottom layer, z3fold, has
473 * information on how the allocations are organized within each z3fold page.
474 * This has the potential to create interesting locking situations between
475 * z3fold and the user, however.
476 *
477 * To avoid these, this is how z3fold_reclaim_page() should be called:
478
479 * The user detects a page should be reclaimed and calls z3fold_reclaim_page().
480 * z3fold_reclaim_page() will remove a z3fold page from the pool LRU list and
481 * call the user-defined eviction handler with the pool and handle as
482 * arguments.
483 *
484 * If the handle can not be evicted, the eviction handler should return
485 * non-zero. z3fold_reclaim_page() will add the z3fold page back to the
486 * appropriate list and try the next z3fold page on the LRU up to
487 * a user defined number of retries.
488 *
489 * If the handle is successfully evicted, the eviction handler should
490 * return 0 _and_ should have called z3fold_free() on the handle. z3fold_free()
491 * contains logic to delay freeing the page if the page is under reclaim,
492 * as indicated by the setting of the PG_reclaim flag on the underlying page.
493 *
494 * If all buddies in the z3fold page are successfully evicted, then the
495 * z3fold page can be freed.
496 *
497 * Returns: 0 if page is successfully freed, otherwise -EINVAL if there are
498 * no pages to evict or an eviction handler is not registered, -EAGAIN if
499 * the retry limit was hit.
500 */
501static int z3fold_reclaim_page(struct z3fold_pool *pool, unsigned int retries)
502{
503 int i, ret = 0, freechunks;
504 struct z3fold_header *zhdr;
505 struct page *page;
506 unsigned long first_handle = 0, middle_handle = 0, last_handle = 0;
507
508 spin_lock(&pool->lock);
509 if (!pool->ops || !pool->ops->evict || list_empty(&pool->lru) ||
510 retries == 0) {
511 spin_unlock(&pool->lock);
512 return -EINVAL;
513 }
514 for (i = 0; i < retries; i++) {
515 page = list_last_entry(&pool->lru, struct page, lru);
516 list_del(&page->lru);
517
518 /* Protect z3fold page against free */
519 set_bit(UNDER_RECLAIM, &page->private);
520 zhdr = page_address(page);
521 if (!test_bit(PAGE_HEADLESS, &page->private)) {
522 list_del(&zhdr->buddy);
523 /*
524 * We need encode the handles before unlocking, since
525 * we can race with free that will set
526 * (first|last)_chunks to 0
527 */
528 first_handle = 0;
529 last_handle = 0;
530 middle_handle = 0;
531 if (zhdr->first_chunks)
532 first_handle = encode_handle(zhdr, FIRST);
533 if (zhdr->middle_chunks)
534 middle_handle = encode_handle(zhdr, MIDDLE);
535 if (zhdr->last_chunks)
536 last_handle = encode_handle(zhdr, LAST);
537 } else {
538 first_handle = encode_handle(zhdr, HEADLESS);
539 last_handle = middle_handle = 0;
540 }
541
542 spin_unlock(&pool->lock);
543
544 /* Issue the eviction callback(s) */
545 if (middle_handle) {
546 ret = pool->ops->evict(pool, middle_handle);
547 if (ret)
548 goto next;
549 }
550 if (first_handle) {
551 ret = pool->ops->evict(pool, first_handle);
552 if (ret)
553 goto next;
554 }
555 if (last_handle) {
556 ret = pool->ops->evict(pool, last_handle);
557 if (ret)
558 goto next;
559 }
560next:
561 spin_lock(&pool->lock);
562 clear_bit(UNDER_RECLAIM, &page->private);
563 if ((test_bit(PAGE_HEADLESS, &page->private) && ret == 0) ||
564 (zhdr->first_chunks == 0 && zhdr->last_chunks == 0 &&
565 zhdr->middle_chunks == 0)) {
566 /*
567 * All buddies are now free, free the z3fold page and
568 * return success.
569 */
570 clear_bit(PAGE_HEADLESS, &page->private);
571 free_z3fold_page(zhdr);
572 pool->pages_nr--;
573 spin_unlock(&pool->lock);
574 return 0;
575 } else if (!test_bit(PAGE_HEADLESS, &page->private)) {
576 if (zhdr->first_chunks != 0 &&
577 zhdr->last_chunks != 0 &&
578 zhdr->middle_chunks != 0) {
579 /* Full, add to buddied list */
580 list_add(&zhdr->buddy, &pool->buddied);
581 } else {
582 z3fold_compact_page(zhdr);
583 /* add to unbuddied list */
584 freechunks = num_free_chunks(zhdr);
585 list_add(&zhdr->buddy,
586 &pool->unbuddied[freechunks]);
587 }
588 }
589
590 /* add to beginning of LRU */
591 list_add(&page->lru, &pool->lru);
592 }
593 spin_unlock(&pool->lock);
594 return -EAGAIN;
595}
596
597/**
598 * z3fold_map() - maps the allocation associated with the given handle
599 * @pool: pool in which the allocation resides
600 * @handle: handle associated with the allocation to be mapped
601 *
602 * Extracts the buddy number from handle and constructs the pointer to the
603 * correct starting chunk within the page.
604 *
605 * Returns: a pointer to the mapped allocation
606 */
607static void *z3fold_map(struct z3fold_pool *pool, unsigned long handle)
608{
609 struct z3fold_header *zhdr;
610 struct page *page;
611 void *addr;
612 enum buddy buddy;
613
614 spin_lock(&pool->lock);
615 zhdr = handle_to_z3fold_header(handle);
616 addr = zhdr;
617 page = virt_to_page(zhdr);
618
619 if (test_bit(PAGE_HEADLESS, &page->private))
620 goto out;
621
622 buddy = handle_to_buddy(handle);
623 switch (buddy) {
624 case FIRST:
625 addr += ZHDR_SIZE_ALIGNED;
626 break;
627 case MIDDLE:
628 addr += zhdr->start_middle << CHUNK_SHIFT;
629 set_bit(MIDDLE_CHUNK_MAPPED, &page->private);
630 break;
631 case LAST:
632 addr += PAGE_SIZE - (zhdr->last_chunks << CHUNK_SHIFT);
633 break;
634 default:
635 pr_err("unknown buddy id %d\n", buddy);
636 WARN_ON(1);
637 addr = NULL;
638 break;
639 }
640out:
641 spin_unlock(&pool->lock);
642 return addr;
643}
644
645/**
646 * z3fold_unmap() - unmaps the allocation associated with the given handle
647 * @pool: pool in which the allocation resides
648 * @handle: handle associated with the allocation to be unmapped
649 */
650static void z3fold_unmap(struct z3fold_pool *pool, unsigned long handle)
651{
652 struct z3fold_header *zhdr;
653 struct page *page;
654 enum buddy buddy;
655
656 spin_lock(&pool->lock);
657 zhdr = handle_to_z3fold_header(handle);
658 page = virt_to_page(zhdr);
659
660 if (test_bit(PAGE_HEADLESS, &page->private)) {
661 spin_unlock(&pool->lock);
662 return;
663 }
664
665 buddy = handle_to_buddy(handle);
666 if (buddy == MIDDLE)
667 clear_bit(MIDDLE_CHUNK_MAPPED, &page->private);
668 spin_unlock(&pool->lock);
669}
670
671/**
672 * z3fold_get_pool_size() - gets the z3fold pool size in pages
673 * @pool: pool whose size is being queried
674 *
675 * Returns: size in pages of the given pool. The pool lock need not be
676 * taken to access pages_nr.
677 */
678static u64 z3fold_get_pool_size(struct z3fold_pool *pool)
679{
680 return pool->pages_nr;
681}
682
683/*****************
684 * zpool
685 ****************/
686
687static int z3fold_zpool_evict(struct z3fold_pool *pool, unsigned long handle)
688{
689 if (pool->zpool && pool->zpool_ops && pool->zpool_ops->evict)
690 return pool->zpool_ops->evict(pool->zpool, handle);
691 else
692 return -ENOENT;
693}
694
695static const struct z3fold_ops z3fold_zpool_ops = {
696 .evict = z3fold_zpool_evict
697};
698
699static void *z3fold_zpool_create(const char *name, gfp_t gfp,
700 const struct zpool_ops *zpool_ops,
701 struct zpool *zpool)
702{
703 struct z3fold_pool *pool;
704
705 pool = z3fold_create_pool(gfp, zpool_ops ? &z3fold_zpool_ops : NULL);
706 if (pool) {
707 pool->zpool = zpool;
708 pool->zpool_ops = zpool_ops;
709 }
710 return pool;
711}
712
713static void z3fold_zpool_destroy(void *pool)
714{
715 z3fold_destroy_pool(pool);
716}
717
718static int z3fold_zpool_malloc(void *pool, size_t size, gfp_t gfp,
719 unsigned long *handle)
720{
721 return z3fold_alloc(pool, size, gfp, handle);
722}
723static void z3fold_zpool_free(void *pool, unsigned long handle)
724{
725 z3fold_free(pool, handle);
726}
727
728static int z3fold_zpool_shrink(void *pool, unsigned int pages,
729 unsigned int *reclaimed)
730{
731 unsigned int total = 0;
732 int ret = -EINVAL;
733
734 while (total < pages) {
735 ret = z3fold_reclaim_page(pool, 8);
736 if (ret < 0)
737 break;
738 total++;
739 }
740
741 if (reclaimed)
742 *reclaimed = total;
743
744 return ret;
745}
746
747static void *z3fold_zpool_map(void *pool, unsigned long handle,
748 enum zpool_mapmode mm)
749{
750 return z3fold_map(pool, handle);
751}
752static void z3fold_zpool_unmap(void *pool, unsigned long handle)
753{
754 z3fold_unmap(pool, handle);
755}
756
757static u64 z3fold_zpool_total_size(void *pool)
758{
759 return z3fold_get_pool_size(pool) * PAGE_SIZE;
760}
761
762static struct zpool_driver z3fold_zpool_driver = {
763 .type = "z3fold",
764 .owner = THIS_MODULE,
765 .create = z3fold_zpool_create,
766 .destroy = z3fold_zpool_destroy,
767 .malloc = z3fold_zpool_malloc,
768 .free = z3fold_zpool_free,
769 .shrink = z3fold_zpool_shrink,
770 .map = z3fold_zpool_map,
771 .unmap = z3fold_zpool_unmap,
772 .total_size = z3fold_zpool_total_size,
773};
774
775MODULE_ALIAS("zpool-z3fold");
776
777static int __init init_z3fold(void)
778{
779 /* Make sure the z3fold header will fit in one chunk */
780 BUILD_BUG_ON(sizeof(struct z3fold_header) > ZHDR_SIZE_ALIGNED);
781 zpool_register_driver(&z3fold_zpool_driver);
782
783 return 0;
784}
785
786static void __exit exit_z3fold(void)
787{
788 zpool_unregister_driver(&z3fold_zpool_driver);
789}
790
791module_init(init_z3fold);
792module_exit(exit_z3fold);
793
794MODULE_LICENSE("GPL");
795MODULE_AUTHOR("Vitaly Wool <vitalywool@gmail.com>");
796MODULE_DESCRIPTION("3-Fold Allocator for Compressed Pages");