Loading...
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * z3fold.c
4 *
5 * Author: Vitaly Wool <vitaly.wool@konsulko.com>
6 * Copyright (C) 2016, Sony Mobile Communications Inc.
7 *
8 * This implementation is based on zbud written by Seth Jennings.
9 *
10 * z3fold is an special purpose allocator for storing compressed pages. It
11 * can store up to three compressed pages per page which improves the
12 * compression ratio of zbud while retaining its main concepts (e. g. always
13 * storing an integral number of objects per page) and simplicity.
14 * It still has simple and deterministic reclaim properties that make it
15 * preferable to a higher density approach (with no requirement on integral
16 * number of object per page) when reclaim is used.
17 *
18 * As in zbud, pages are divided into "chunks". The size of the chunks is
19 * fixed at compile time and is determined by NCHUNKS_ORDER below.
20 *
21 * z3fold doesn't export any API and is meant to be used via zpool API.
22 */
23
24#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
25
26#include <linux/atomic.h>
27#include <linux/sched.h>
28#include <linux/cpumask.h>
29#include <linux/list.h>
30#include <linux/mm.h>
31#include <linux/module.h>
32#include <linux/page-flags.h>
33#include <linux/migrate.h>
34#include <linux/node.h>
35#include <linux/compaction.h>
36#include <linux/percpu.h>
37#include <linux/preempt.h>
38#include <linux/workqueue.h>
39#include <linux/slab.h>
40#include <linux/spinlock.h>
41#include <linux/zpool.h>
42#include <linux/kmemleak.h>
43
44/*
45 * NCHUNKS_ORDER determines the internal allocation granularity, effectively
46 * adjusting internal fragmentation. It also determines the number of
47 * freelists maintained in each pool. NCHUNKS_ORDER of 6 means that the
48 * allocation granularity will be in chunks of size PAGE_SIZE/64. Some chunks
49 * in the beginning of an allocated page are occupied by z3fold header, so
50 * NCHUNKS will be calculated to 63 (or 62 in case CONFIG_DEBUG_SPINLOCK=y),
51 * which shows the max number of free chunks in z3fold page, also there will
52 * be 63, or 62, respectively, freelists per pool.
53 */
54#define NCHUNKS_ORDER 6
55
56#define CHUNK_SHIFT (PAGE_SHIFT - NCHUNKS_ORDER)
57#define CHUNK_SIZE (1 << CHUNK_SHIFT)
58#define ZHDR_SIZE_ALIGNED round_up(sizeof(struct z3fold_header), CHUNK_SIZE)
59#define ZHDR_CHUNKS (ZHDR_SIZE_ALIGNED >> CHUNK_SHIFT)
60#define TOTAL_CHUNKS (PAGE_SIZE >> CHUNK_SHIFT)
61#define NCHUNKS (TOTAL_CHUNKS - ZHDR_CHUNKS)
62
63#define BUDDY_MASK (0x3)
64#define BUDDY_SHIFT 2
65#define SLOTS_ALIGN (0x40)
66
67/*****************
68 * Structures
69*****************/
70struct z3fold_pool;
71
72enum buddy {
73 HEADLESS = 0,
74 FIRST,
75 MIDDLE,
76 LAST,
77 BUDDIES_MAX = LAST
78};
79
80struct z3fold_buddy_slots {
81 /*
82 * we are using BUDDY_MASK in handle_to_buddy etc. so there should
83 * be enough slots to hold all possible variants
84 */
85 unsigned long slot[BUDDY_MASK + 1];
86 unsigned long pool; /* back link */
87 rwlock_t lock;
88};
89#define HANDLE_FLAG_MASK (0x03)
90
91/*
92 * struct z3fold_header - z3fold page metadata occupying first chunks of each
93 * z3fold page, except for HEADLESS pages
94 * @buddy: links the z3fold page into the relevant list in the
95 * pool
96 * @page_lock: per-page lock
97 * @refcount: reference count for the z3fold page
98 * @work: work_struct for page layout optimization
99 * @slots: pointer to the structure holding buddy slots
100 * @pool: pointer to the containing pool
101 * @cpu: CPU which this page "belongs" to
102 * @first_chunks: the size of the first buddy in chunks, 0 if free
103 * @middle_chunks: the size of the middle buddy in chunks, 0 if free
104 * @last_chunks: the size of the last buddy in chunks, 0 if free
105 * @first_num: the starting number (for the first handle)
106 * @mapped_count: the number of objects currently mapped
107 */
108struct z3fold_header {
109 struct list_head buddy;
110 spinlock_t page_lock;
111 struct kref refcount;
112 struct work_struct work;
113 struct z3fold_buddy_slots *slots;
114 struct z3fold_pool *pool;
115 short cpu;
116 unsigned short first_chunks;
117 unsigned short middle_chunks;
118 unsigned short last_chunks;
119 unsigned short start_middle;
120 unsigned short first_num:2;
121 unsigned short mapped_count:2;
122 unsigned short foreign_handles:2;
123};
124
125/**
126 * struct z3fold_pool - stores metadata for each z3fold pool
127 * @name: pool name
128 * @lock: protects pool unbuddied/lru lists
129 * @stale_lock: protects pool stale page list
130 * @unbuddied: per-cpu array of lists tracking z3fold pages that contain 2-
131 * buddies; the list each z3fold page is added to depends on
132 * the size of its free region.
133 * @lru: list tracking the z3fold pages in LRU order by most recently
134 * added buddy.
135 * @stale: list of pages marked for freeing
136 * @pages_nr: number of z3fold pages in the pool.
137 * @c_handle: cache for z3fold_buddy_slots allocation
138 * @zpool: zpool driver
139 * @zpool_ops: zpool operations structure with an evict callback
140 * @compact_wq: workqueue for page layout background optimization
141 * @release_wq: workqueue for safe page release
142 * @work: work_struct for safe page release
143 *
144 * This structure is allocated at pool creation time and maintains metadata
145 * pertaining to a particular z3fold pool.
146 */
147struct z3fold_pool {
148 const char *name;
149 spinlock_t lock;
150 spinlock_t stale_lock;
151 struct list_head *unbuddied;
152 struct list_head lru;
153 struct list_head stale;
154 atomic64_t pages_nr;
155 struct kmem_cache *c_handle;
156 struct zpool *zpool;
157 const struct zpool_ops *zpool_ops;
158 struct workqueue_struct *compact_wq;
159 struct workqueue_struct *release_wq;
160 struct work_struct work;
161};
162
163/*
164 * Internal z3fold page flags
165 */
166enum z3fold_page_flags {
167 PAGE_HEADLESS = 0,
168 MIDDLE_CHUNK_MAPPED,
169 NEEDS_COMPACTING,
170 PAGE_STALE,
171 PAGE_CLAIMED, /* by either reclaim or free */
172 PAGE_MIGRATED, /* page is migrated and soon to be released */
173};
174
175/*
176 * handle flags, go under HANDLE_FLAG_MASK
177 */
178enum z3fold_handle_flags {
179 HANDLES_NOFREE = 0,
180};
181
182/*
183 * Forward declarations
184 */
185static struct z3fold_header *__z3fold_alloc(struct z3fold_pool *, size_t, bool);
186static void compact_page_work(struct work_struct *w);
187
188/*****************
189 * Helpers
190*****************/
191
192/* Converts an allocation size in bytes to size in z3fold chunks */
193static int size_to_chunks(size_t size)
194{
195 return (size + CHUNK_SIZE - 1) >> CHUNK_SHIFT;
196}
197
198#define for_each_unbuddied_list(_iter, _begin) \
199 for ((_iter) = (_begin); (_iter) < NCHUNKS; (_iter)++)
200
201static inline struct z3fold_buddy_slots *alloc_slots(struct z3fold_pool *pool,
202 gfp_t gfp)
203{
204 struct z3fold_buddy_slots *slots = kmem_cache_zalloc(pool->c_handle,
205 gfp);
206
207 if (slots) {
208 /* It will be freed separately in free_handle(). */
209 kmemleak_not_leak(slots);
210 slots->pool = (unsigned long)pool;
211 rwlock_init(&slots->lock);
212 }
213
214 return slots;
215}
216
217static inline struct z3fold_pool *slots_to_pool(struct z3fold_buddy_slots *s)
218{
219 return (struct z3fold_pool *)(s->pool & ~HANDLE_FLAG_MASK);
220}
221
222static inline struct z3fold_buddy_slots *handle_to_slots(unsigned long handle)
223{
224 return (struct z3fold_buddy_slots *)(handle & ~(SLOTS_ALIGN - 1));
225}
226
227/* Lock a z3fold page */
228static inline void z3fold_page_lock(struct z3fold_header *zhdr)
229{
230 spin_lock(&zhdr->page_lock);
231}
232
233/* Try to lock a z3fold page */
234static inline int z3fold_page_trylock(struct z3fold_header *zhdr)
235{
236 return spin_trylock(&zhdr->page_lock);
237}
238
239/* Unlock a z3fold page */
240static inline void z3fold_page_unlock(struct z3fold_header *zhdr)
241{
242 spin_unlock(&zhdr->page_lock);
243}
244
245/* return locked z3fold page if it's not headless */
246static inline struct z3fold_header *get_z3fold_header(unsigned long handle)
247{
248 struct z3fold_buddy_slots *slots;
249 struct z3fold_header *zhdr;
250 int locked = 0;
251
252 if (!(handle & (1 << PAGE_HEADLESS))) {
253 slots = handle_to_slots(handle);
254 do {
255 unsigned long addr;
256
257 read_lock(&slots->lock);
258 addr = *(unsigned long *)handle;
259 zhdr = (struct z3fold_header *)(addr & PAGE_MASK);
260 locked = z3fold_page_trylock(zhdr);
261 read_unlock(&slots->lock);
262 if (locked) {
263 struct page *page = virt_to_page(zhdr);
264
265 if (!test_bit(PAGE_MIGRATED, &page->private))
266 break;
267 z3fold_page_unlock(zhdr);
268 }
269 cpu_relax();
270 } while (true);
271 } else {
272 zhdr = (struct z3fold_header *)(handle & PAGE_MASK);
273 }
274
275 return zhdr;
276}
277
278static inline void put_z3fold_header(struct z3fold_header *zhdr)
279{
280 struct page *page = virt_to_page(zhdr);
281
282 if (!test_bit(PAGE_HEADLESS, &page->private))
283 z3fold_page_unlock(zhdr);
284}
285
286static inline void free_handle(unsigned long handle, struct z3fold_header *zhdr)
287{
288 struct z3fold_buddy_slots *slots;
289 int i;
290 bool is_free;
291
292 if (WARN_ON(*(unsigned long *)handle == 0))
293 return;
294
295 slots = handle_to_slots(handle);
296 write_lock(&slots->lock);
297 *(unsigned long *)handle = 0;
298
299 if (test_bit(HANDLES_NOFREE, &slots->pool)) {
300 write_unlock(&slots->lock);
301 return; /* simple case, nothing else to do */
302 }
303
304 if (zhdr->slots != slots)
305 zhdr->foreign_handles--;
306
307 is_free = true;
308 for (i = 0; i <= BUDDY_MASK; i++) {
309 if (slots->slot[i]) {
310 is_free = false;
311 break;
312 }
313 }
314 write_unlock(&slots->lock);
315
316 if (is_free) {
317 struct z3fold_pool *pool = slots_to_pool(slots);
318
319 if (zhdr->slots == slots)
320 zhdr->slots = NULL;
321 kmem_cache_free(pool->c_handle, slots);
322 }
323}
324
325/* Initializes the z3fold header of a newly allocated z3fold page */
326static struct z3fold_header *init_z3fold_page(struct page *page, bool headless,
327 struct z3fold_pool *pool, gfp_t gfp)
328{
329 struct z3fold_header *zhdr = page_address(page);
330 struct z3fold_buddy_slots *slots;
331
332 INIT_LIST_HEAD(&page->lru);
333 clear_bit(PAGE_HEADLESS, &page->private);
334 clear_bit(MIDDLE_CHUNK_MAPPED, &page->private);
335 clear_bit(NEEDS_COMPACTING, &page->private);
336 clear_bit(PAGE_STALE, &page->private);
337 clear_bit(PAGE_CLAIMED, &page->private);
338 clear_bit(PAGE_MIGRATED, &page->private);
339 if (headless)
340 return zhdr;
341
342 slots = alloc_slots(pool, gfp);
343 if (!slots)
344 return NULL;
345
346 memset(zhdr, 0, sizeof(*zhdr));
347 spin_lock_init(&zhdr->page_lock);
348 kref_init(&zhdr->refcount);
349 zhdr->cpu = -1;
350 zhdr->slots = slots;
351 zhdr->pool = pool;
352 INIT_LIST_HEAD(&zhdr->buddy);
353 INIT_WORK(&zhdr->work, compact_page_work);
354 return zhdr;
355}
356
357/* Resets the struct page fields and frees the page */
358static void free_z3fold_page(struct page *page, bool headless)
359{
360 if (!headless) {
361 lock_page(page);
362 __ClearPageMovable(page);
363 unlock_page(page);
364 }
365 __free_page(page);
366}
367
368/* Helper function to build the index */
369static inline int __idx(struct z3fold_header *zhdr, enum buddy bud)
370{
371 return (bud + zhdr->first_num) & BUDDY_MASK;
372}
373
374/*
375 * Encodes the handle of a particular buddy within a z3fold page
376 * Pool lock should be held as this function accesses first_num
377 */
378static unsigned long __encode_handle(struct z3fold_header *zhdr,
379 struct z3fold_buddy_slots *slots,
380 enum buddy bud)
381{
382 unsigned long h = (unsigned long)zhdr;
383 int idx = 0;
384
385 /*
386 * For a headless page, its handle is its pointer with the extra
387 * PAGE_HEADLESS bit set
388 */
389 if (bud == HEADLESS)
390 return h | (1 << PAGE_HEADLESS);
391
392 /* otherwise, return pointer to encoded handle */
393 idx = __idx(zhdr, bud);
394 h += idx;
395 if (bud == LAST)
396 h |= (zhdr->last_chunks << BUDDY_SHIFT);
397
398 write_lock(&slots->lock);
399 slots->slot[idx] = h;
400 write_unlock(&slots->lock);
401 return (unsigned long)&slots->slot[idx];
402}
403
404static unsigned long encode_handle(struct z3fold_header *zhdr, enum buddy bud)
405{
406 return __encode_handle(zhdr, zhdr->slots, bud);
407}
408
409/* only for LAST bud, returns zero otherwise */
410static unsigned short handle_to_chunks(unsigned long handle)
411{
412 struct z3fold_buddy_slots *slots = handle_to_slots(handle);
413 unsigned long addr;
414
415 read_lock(&slots->lock);
416 addr = *(unsigned long *)handle;
417 read_unlock(&slots->lock);
418 return (addr & ~PAGE_MASK) >> BUDDY_SHIFT;
419}
420
421/*
422 * (handle & BUDDY_MASK) < zhdr->first_num is possible in encode_handle
423 * but that doesn't matter. because the masking will result in the
424 * correct buddy number.
425 */
426static enum buddy handle_to_buddy(unsigned long handle)
427{
428 struct z3fold_header *zhdr;
429 struct z3fold_buddy_slots *slots = handle_to_slots(handle);
430 unsigned long addr;
431
432 read_lock(&slots->lock);
433 WARN_ON(handle & (1 << PAGE_HEADLESS));
434 addr = *(unsigned long *)handle;
435 read_unlock(&slots->lock);
436 zhdr = (struct z3fold_header *)(addr & PAGE_MASK);
437 return (addr - zhdr->first_num) & BUDDY_MASK;
438}
439
440static inline struct z3fold_pool *zhdr_to_pool(struct z3fold_header *zhdr)
441{
442 return zhdr->pool;
443}
444
445static void __release_z3fold_page(struct z3fold_header *zhdr, bool locked)
446{
447 struct page *page = virt_to_page(zhdr);
448 struct z3fold_pool *pool = zhdr_to_pool(zhdr);
449
450 WARN_ON(!list_empty(&zhdr->buddy));
451 set_bit(PAGE_STALE, &page->private);
452 clear_bit(NEEDS_COMPACTING, &page->private);
453 spin_lock(&pool->lock);
454 if (!list_empty(&page->lru))
455 list_del_init(&page->lru);
456 spin_unlock(&pool->lock);
457
458 if (locked)
459 z3fold_page_unlock(zhdr);
460
461 spin_lock(&pool->stale_lock);
462 list_add(&zhdr->buddy, &pool->stale);
463 queue_work(pool->release_wq, &pool->work);
464 spin_unlock(&pool->stale_lock);
465
466 atomic64_dec(&pool->pages_nr);
467}
468
469static void release_z3fold_page_locked(struct kref *ref)
470{
471 struct z3fold_header *zhdr = container_of(ref, struct z3fold_header,
472 refcount);
473 WARN_ON(z3fold_page_trylock(zhdr));
474 __release_z3fold_page(zhdr, true);
475}
476
477static void release_z3fold_page_locked_list(struct kref *ref)
478{
479 struct z3fold_header *zhdr = container_of(ref, struct z3fold_header,
480 refcount);
481 struct z3fold_pool *pool = zhdr_to_pool(zhdr);
482
483 spin_lock(&pool->lock);
484 list_del_init(&zhdr->buddy);
485 spin_unlock(&pool->lock);
486
487 WARN_ON(z3fold_page_trylock(zhdr));
488 __release_z3fold_page(zhdr, true);
489}
490
491static void free_pages_work(struct work_struct *w)
492{
493 struct z3fold_pool *pool = container_of(w, struct z3fold_pool, work);
494
495 spin_lock(&pool->stale_lock);
496 while (!list_empty(&pool->stale)) {
497 struct z3fold_header *zhdr = list_first_entry(&pool->stale,
498 struct z3fold_header, buddy);
499 struct page *page = virt_to_page(zhdr);
500
501 list_del(&zhdr->buddy);
502 if (WARN_ON(!test_bit(PAGE_STALE, &page->private)))
503 continue;
504 spin_unlock(&pool->stale_lock);
505 cancel_work_sync(&zhdr->work);
506 free_z3fold_page(page, false);
507 cond_resched();
508 spin_lock(&pool->stale_lock);
509 }
510 spin_unlock(&pool->stale_lock);
511}
512
513/*
514 * Returns the number of free chunks in a z3fold page.
515 * NB: can't be used with HEADLESS pages.
516 */
517static int num_free_chunks(struct z3fold_header *zhdr)
518{
519 int nfree;
520 /*
521 * If there is a middle object, pick up the bigger free space
522 * either before or after it. Otherwise just subtract the number
523 * of chunks occupied by the first and the last objects.
524 */
525 if (zhdr->middle_chunks != 0) {
526 int nfree_before = zhdr->first_chunks ?
527 0 : zhdr->start_middle - ZHDR_CHUNKS;
528 int nfree_after = zhdr->last_chunks ?
529 0 : TOTAL_CHUNKS -
530 (zhdr->start_middle + zhdr->middle_chunks);
531 nfree = max(nfree_before, nfree_after);
532 } else
533 nfree = NCHUNKS - zhdr->first_chunks - zhdr->last_chunks;
534 return nfree;
535}
536
537/* Add to the appropriate unbuddied list */
538static inline void add_to_unbuddied(struct z3fold_pool *pool,
539 struct z3fold_header *zhdr)
540{
541 if (zhdr->first_chunks == 0 || zhdr->last_chunks == 0 ||
542 zhdr->middle_chunks == 0) {
543 struct list_head *unbuddied;
544 int freechunks = num_free_chunks(zhdr);
545
546 migrate_disable();
547 unbuddied = this_cpu_ptr(pool->unbuddied);
548 spin_lock(&pool->lock);
549 list_add(&zhdr->buddy, &unbuddied[freechunks]);
550 spin_unlock(&pool->lock);
551 zhdr->cpu = smp_processor_id();
552 migrate_enable();
553 }
554}
555
556static inline enum buddy get_free_buddy(struct z3fold_header *zhdr, int chunks)
557{
558 enum buddy bud = HEADLESS;
559
560 if (zhdr->middle_chunks) {
561 if (!zhdr->first_chunks &&
562 chunks <= zhdr->start_middle - ZHDR_CHUNKS)
563 bud = FIRST;
564 else if (!zhdr->last_chunks)
565 bud = LAST;
566 } else {
567 if (!zhdr->first_chunks)
568 bud = FIRST;
569 else if (!zhdr->last_chunks)
570 bud = LAST;
571 else
572 bud = MIDDLE;
573 }
574
575 return bud;
576}
577
578static inline void *mchunk_memmove(struct z3fold_header *zhdr,
579 unsigned short dst_chunk)
580{
581 void *beg = zhdr;
582 return memmove(beg + (dst_chunk << CHUNK_SHIFT),
583 beg + (zhdr->start_middle << CHUNK_SHIFT),
584 zhdr->middle_chunks << CHUNK_SHIFT);
585}
586
587static inline bool buddy_single(struct z3fold_header *zhdr)
588{
589 return !((zhdr->first_chunks && zhdr->middle_chunks) ||
590 (zhdr->first_chunks && zhdr->last_chunks) ||
591 (zhdr->middle_chunks && zhdr->last_chunks));
592}
593
594static struct z3fold_header *compact_single_buddy(struct z3fold_header *zhdr)
595{
596 struct z3fold_pool *pool = zhdr_to_pool(zhdr);
597 void *p = zhdr;
598 unsigned long old_handle = 0;
599 size_t sz = 0;
600 struct z3fold_header *new_zhdr = NULL;
601 int first_idx = __idx(zhdr, FIRST);
602 int middle_idx = __idx(zhdr, MIDDLE);
603 int last_idx = __idx(zhdr, LAST);
604 unsigned short *moved_chunks = NULL;
605
606 /*
607 * No need to protect slots here -- all the slots are "local" and
608 * the page lock is already taken
609 */
610 if (zhdr->first_chunks && zhdr->slots->slot[first_idx]) {
611 p += ZHDR_SIZE_ALIGNED;
612 sz = zhdr->first_chunks << CHUNK_SHIFT;
613 old_handle = (unsigned long)&zhdr->slots->slot[first_idx];
614 moved_chunks = &zhdr->first_chunks;
615 } else if (zhdr->middle_chunks && zhdr->slots->slot[middle_idx]) {
616 p += zhdr->start_middle << CHUNK_SHIFT;
617 sz = zhdr->middle_chunks << CHUNK_SHIFT;
618 old_handle = (unsigned long)&zhdr->slots->slot[middle_idx];
619 moved_chunks = &zhdr->middle_chunks;
620 } else if (zhdr->last_chunks && zhdr->slots->slot[last_idx]) {
621 p += PAGE_SIZE - (zhdr->last_chunks << CHUNK_SHIFT);
622 sz = zhdr->last_chunks << CHUNK_SHIFT;
623 old_handle = (unsigned long)&zhdr->slots->slot[last_idx];
624 moved_chunks = &zhdr->last_chunks;
625 }
626
627 if (sz > 0) {
628 enum buddy new_bud = HEADLESS;
629 short chunks = size_to_chunks(sz);
630 void *q;
631
632 new_zhdr = __z3fold_alloc(pool, sz, false);
633 if (!new_zhdr)
634 return NULL;
635
636 if (WARN_ON(new_zhdr == zhdr))
637 goto out_fail;
638
639 new_bud = get_free_buddy(new_zhdr, chunks);
640 q = new_zhdr;
641 switch (new_bud) {
642 case FIRST:
643 new_zhdr->first_chunks = chunks;
644 q += ZHDR_SIZE_ALIGNED;
645 break;
646 case MIDDLE:
647 new_zhdr->middle_chunks = chunks;
648 new_zhdr->start_middle =
649 new_zhdr->first_chunks + ZHDR_CHUNKS;
650 q += new_zhdr->start_middle << CHUNK_SHIFT;
651 break;
652 case LAST:
653 new_zhdr->last_chunks = chunks;
654 q += PAGE_SIZE - (new_zhdr->last_chunks << CHUNK_SHIFT);
655 break;
656 default:
657 goto out_fail;
658 }
659 new_zhdr->foreign_handles++;
660 memcpy(q, p, sz);
661 write_lock(&zhdr->slots->lock);
662 *(unsigned long *)old_handle = (unsigned long)new_zhdr +
663 __idx(new_zhdr, new_bud);
664 if (new_bud == LAST)
665 *(unsigned long *)old_handle |=
666 (new_zhdr->last_chunks << BUDDY_SHIFT);
667 write_unlock(&zhdr->slots->lock);
668 add_to_unbuddied(pool, new_zhdr);
669 z3fold_page_unlock(new_zhdr);
670
671 *moved_chunks = 0;
672 }
673
674 return new_zhdr;
675
676out_fail:
677 if (new_zhdr && !kref_put(&new_zhdr->refcount, release_z3fold_page_locked)) {
678 add_to_unbuddied(pool, new_zhdr);
679 z3fold_page_unlock(new_zhdr);
680 }
681 return NULL;
682
683}
684
685#define BIG_CHUNK_GAP 3
686/* Has to be called with lock held */
687static int z3fold_compact_page(struct z3fold_header *zhdr)
688{
689 struct page *page = virt_to_page(zhdr);
690
691 if (test_bit(MIDDLE_CHUNK_MAPPED, &page->private))
692 return 0; /* can't move middle chunk, it's used */
693
694 if (unlikely(PageIsolated(page)))
695 return 0;
696
697 if (zhdr->middle_chunks == 0)
698 return 0; /* nothing to compact */
699
700 if (zhdr->first_chunks == 0 && zhdr->last_chunks == 0) {
701 /* move to the beginning */
702 mchunk_memmove(zhdr, ZHDR_CHUNKS);
703 zhdr->first_chunks = zhdr->middle_chunks;
704 zhdr->middle_chunks = 0;
705 zhdr->start_middle = 0;
706 zhdr->first_num++;
707 return 1;
708 }
709
710 /*
711 * moving data is expensive, so let's only do that if
712 * there's substantial gain (at least BIG_CHUNK_GAP chunks)
713 */
714 if (zhdr->first_chunks != 0 && zhdr->last_chunks == 0 &&
715 zhdr->start_middle - (zhdr->first_chunks + ZHDR_CHUNKS) >=
716 BIG_CHUNK_GAP) {
717 mchunk_memmove(zhdr, zhdr->first_chunks + ZHDR_CHUNKS);
718 zhdr->start_middle = zhdr->first_chunks + ZHDR_CHUNKS;
719 return 1;
720 } else if (zhdr->last_chunks != 0 && zhdr->first_chunks == 0 &&
721 TOTAL_CHUNKS - (zhdr->last_chunks + zhdr->start_middle
722 + zhdr->middle_chunks) >=
723 BIG_CHUNK_GAP) {
724 unsigned short new_start = TOTAL_CHUNKS - zhdr->last_chunks -
725 zhdr->middle_chunks;
726 mchunk_memmove(zhdr, new_start);
727 zhdr->start_middle = new_start;
728 return 1;
729 }
730
731 return 0;
732}
733
734static void do_compact_page(struct z3fold_header *zhdr, bool locked)
735{
736 struct z3fold_pool *pool = zhdr_to_pool(zhdr);
737 struct page *page;
738
739 page = virt_to_page(zhdr);
740 if (locked)
741 WARN_ON(z3fold_page_trylock(zhdr));
742 else
743 z3fold_page_lock(zhdr);
744 if (WARN_ON(!test_and_clear_bit(NEEDS_COMPACTING, &page->private))) {
745 z3fold_page_unlock(zhdr);
746 return;
747 }
748 spin_lock(&pool->lock);
749 list_del_init(&zhdr->buddy);
750 spin_unlock(&pool->lock);
751
752 if (kref_put(&zhdr->refcount, release_z3fold_page_locked))
753 return;
754
755 if (test_bit(PAGE_STALE, &page->private) ||
756 test_and_set_bit(PAGE_CLAIMED, &page->private)) {
757 z3fold_page_unlock(zhdr);
758 return;
759 }
760
761 if (!zhdr->foreign_handles && buddy_single(zhdr) &&
762 zhdr->mapped_count == 0 && compact_single_buddy(zhdr)) {
763 if (!kref_put(&zhdr->refcount, release_z3fold_page_locked)) {
764 clear_bit(PAGE_CLAIMED, &page->private);
765 z3fold_page_unlock(zhdr);
766 }
767 return;
768 }
769
770 z3fold_compact_page(zhdr);
771 add_to_unbuddied(pool, zhdr);
772 clear_bit(PAGE_CLAIMED, &page->private);
773 z3fold_page_unlock(zhdr);
774}
775
776static void compact_page_work(struct work_struct *w)
777{
778 struct z3fold_header *zhdr = container_of(w, struct z3fold_header,
779 work);
780
781 do_compact_page(zhdr, false);
782}
783
784/* returns _locked_ z3fold page header or NULL */
785static inline struct z3fold_header *__z3fold_alloc(struct z3fold_pool *pool,
786 size_t size, bool can_sleep)
787{
788 struct z3fold_header *zhdr = NULL;
789 struct page *page;
790 struct list_head *unbuddied;
791 int chunks = size_to_chunks(size), i;
792
793lookup:
794 migrate_disable();
795 /* First, try to find an unbuddied z3fold page. */
796 unbuddied = this_cpu_ptr(pool->unbuddied);
797 for_each_unbuddied_list(i, chunks) {
798 struct list_head *l = &unbuddied[i];
799
800 zhdr = list_first_entry_or_null(READ_ONCE(l),
801 struct z3fold_header, buddy);
802
803 if (!zhdr)
804 continue;
805
806 /* Re-check under lock. */
807 spin_lock(&pool->lock);
808 if (unlikely(zhdr != list_first_entry(READ_ONCE(l),
809 struct z3fold_header, buddy)) ||
810 !z3fold_page_trylock(zhdr)) {
811 spin_unlock(&pool->lock);
812 zhdr = NULL;
813 migrate_enable();
814 if (can_sleep)
815 cond_resched();
816 goto lookup;
817 }
818 list_del_init(&zhdr->buddy);
819 zhdr->cpu = -1;
820 spin_unlock(&pool->lock);
821
822 page = virt_to_page(zhdr);
823 if (test_bit(NEEDS_COMPACTING, &page->private) ||
824 test_bit(PAGE_CLAIMED, &page->private)) {
825 z3fold_page_unlock(zhdr);
826 zhdr = NULL;
827 migrate_enable();
828 if (can_sleep)
829 cond_resched();
830 goto lookup;
831 }
832
833 /*
834 * this page could not be removed from its unbuddied
835 * list while pool lock was held, and then we've taken
836 * page lock so kref_put could not be called before
837 * we got here, so it's safe to just call kref_get()
838 */
839 kref_get(&zhdr->refcount);
840 break;
841 }
842 migrate_enable();
843
844 if (!zhdr) {
845 int cpu;
846
847 /* look for _exact_ match on other cpus' lists */
848 for_each_online_cpu(cpu) {
849 struct list_head *l;
850
851 unbuddied = per_cpu_ptr(pool->unbuddied, cpu);
852 spin_lock(&pool->lock);
853 l = &unbuddied[chunks];
854
855 zhdr = list_first_entry_or_null(READ_ONCE(l),
856 struct z3fold_header, buddy);
857
858 if (!zhdr || !z3fold_page_trylock(zhdr)) {
859 spin_unlock(&pool->lock);
860 zhdr = NULL;
861 continue;
862 }
863 list_del_init(&zhdr->buddy);
864 zhdr->cpu = -1;
865 spin_unlock(&pool->lock);
866
867 page = virt_to_page(zhdr);
868 if (test_bit(NEEDS_COMPACTING, &page->private) ||
869 test_bit(PAGE_CLAIMED, &page->private)) {
870 z3fold_page_unlock(zhdr);
871 zhdr = NULL;
872 if (can_sleep)
873 cond_resched();
874 continue;
875 }
876 kref_get(&zhdr->refcount);
877 break;
878 }
879 }
880
881 if (zhdr && !zhdr->slots) {
882 zhdr->slots = alloc_slots(pool, GFP_ATOMIC);
883 if (!zhdr->slots)
884 goto out_fail;
885 }
886 return zhdr;
887
888out_fail:
889 if (!kref_put(&zhdr->refcount, release_z3fold_page_locked)) {
890 add_to_unbuddied(pool, zhdr);
891 z3fold_page_unlock(zhdr);
892 }
893 return NULL;
894}
895
896/*
897 * API Functions
898 */
899
900/**
901 * z3fold_create_pool() - create a new z3fold pool
902 * @name: pool name
903 * @gfp: gfp flags when allocating the z3fold pool structure
904 *
905 * Return: pointer to the new z3fold pool or NULL if the metadata allocation
906 * failed.
907 */
908static struct z3fold_pool *z3fold_create_pool(const char *name, gfp_t gfp)
909{
910 struct z3fold_pool *pool = NULL;
911 int i, cpu;
912
913 pool = kzalloc(sizeof(struct z3fold_pool), gfp);
914 if (!pool)
915 goto out;
916 pool->c_handle = kmem_cache_create("z3fold_handle",
917 sizeof(struct z3fold_buddy_slots),
918 SLOTS_ALIGN, 0, NULL);
919 if (!pool->c_handle)
920 goto out_c;
921 spin_lock_init(&pool->lock);
922 spin_lock_init(&pool->stale_lock);
923 pool->unbuddied = __alloc_percpu(sizeof(struct list_head) * NCHUNKS,
924 __alignof__(struct list_head));
925 if (!pool->unbuddied)
926 goto out_pool;
927 for_each_possible_cpu(cpu) {
928 struct list_head *unbuddied =
929 per_cpu_ptr(pool->unbuddied, cpu);
930 for_each_unbuddied_list(i, 0)
931 INIT_LIST_HEAD(&unbuddied[i]);
932 }
933 INIT_LIST_HEAD(&pool->lru);
934 INIT_LIST_HEAD(&pool->stale);
935 atomic64_set(&pool->pages_nr, 0);
936 pool->name = name;
937 pool->compact_wq = create_singlethread_workqueue(pool->name);
938 if (!pool->compact_wq)
939 goto out_unbuddied;
940 pool->release_wq = create_singlethread_workqueue(pool->name);
941 if (!pool->release_wq)
942 goto out_wq;
943 INIT_WORK(&pool->work, free_pages_work);
944 return pool;
945
946out_wq:
947 destroy_workqueue(pool->compact_wq);
948out_unbuddied:
949 free_percpu(pool->unbuddied);
950out_pool:
951 kmem_cache_destroy(pool->c_handle);
952out_c:
953 kfree(pool);
954out:
955 return NULL;
956}
957
958/**
959 * z3fold_destroy_pool() - destroys an existing z3fold pool
960 * @pool: the z3fold pool to be destroyed
961 *
962 * The pool should be emptied before this function is called.
963 */
964static void z3fold_destroy_pool(struct z3fold_pool *pool)
965{
966 kmem_cache_destroy(pool->c_handle);
967
968 /*
969 * We need to destroy pool->compact_wq before pool->release_wq,
970 * as any pending work on pool->compact_wq will call
971 * queue_work(pool->release_wq, &pool->work).
972 *
973 * There are still outstanding pages until both workqueues are drained,
974 * so we cannot unregister migration until then.
975 */
976
977 destroy_workqueue(pool->compact_wq);
978 destroy_workqueue(pool->release_wq);
979 free_percpu(pool->unbuddied);
980 kfree(pool);
981}
982
983static const struct movable_operations z3fold_mops;
984
985/**
986 * z3fold_alloc() - allocates a region of a given size
987 * @pool: z3fold pool from which to allocate
988 * @size: size in bytes of the desired allocation
989 * @gfp: gfp flags used if the pool needs to grow
990 * @handle: handle of the new allocation
991 *
992 * This function will attempt to find a free region in the pool large enough to
993 * satisfy the allocation request. A search of the unbuddied lists is
994 * performed first. If no suitable free region is found, then a new page is
995 * allocated and added to the pool to satisfy the request.
996 *
997 * Return: 0 if success and handle is set, otherwise -EINVAL if the size or
998 * gfp arguments are invalid or -ENOMEM if the pool was unable to allocate
999 * a new page.
1000 */
1001static int z3fold_alloc(struct z3fold_pool *pool, size_t size, gfp_t gfp,
1002 unsigned long *handle)
1003{
1004 int chunks = size_to_chunks(size);
1005 struct z3fold_header *zhdr = NULL;
1006 struct page *page = NULL;
1007 enum buddy bud;
1008 bool can_sleep = gfpflags_allow_blocking(gfp);
1009
1010 if (!size || (gfp & __GFP_HIGHMEM))
1011 return -EINVAL;
1012
1013 if (size > PAGE_SIZE)
1014 return -ENOSPC;
1015
1016 if (size > PAGE_SIZE - ZHDR_SIZE_ALIGNED - CHUNK_SIZE)
1017 bud = HEADLESS;
1018 else {
1019retry:
1020 zhdr = __z3fold_alloc(pool, size, can_sleep);
1021 if (zhdr) {
1022 bud = get_free_buddy(zhdr, chunks);
1023 if (bud == HEADLESS) {
1024 if (!kref_put(&zhdr->refcount,
1025 release_z3fold_page_locked))
1026 z3fold_page_unlock(zhdr);
1027 pr_err("No free chunks in unbuddied\n");
1028 WARN_ON(1);
1029 goto retry;
1030 }
1031 page = virt_to_page(zhdr);
1032 goto found;
1033 }
1034 bud = FIRST;
1035 }
1036
1037 page = alloc_page(gfp);
1038 if (!page)
1039 return -ENOMEM;
1040
1041 zhdr = init_z3fold_page(page, bud == HEADLESS, pool, gfp);
1042 if (!zhdr) {
1043 __free_page(page);
1044 return -ENOMEM;
1045 }
1046 atomic64_inc(&pool->pages_nr);
1047
1048 if (bud == HEADLESS) {
1049 set_bit(PAGE_HEADLESS, &page->private);
1050 goto headless;
1051 }
1052 if (can_sleep) {
1053 lock_page(page);
1054 __SetPageMovable(page, &z3fold_mops);
1055 unlock_page(page);
1056 } else {
1057 WARN_ON(!trylock_page(page));
1058 __SetPageMovable(page, &z3fold_mops);
1059 unlock_page(page);
1060 }
1061 z3fold_page_lock(zhdr);
1062
1063found:
1064 if (bud == FIRST)
1065 zhdr->first_chunks = chunks;
1066 else if (bud == LAST)
1067 zhdr->last_chunks = chunks;
1068 else {
1069 zhdr->middle_chunks = chunks;
1070 zhdr->start_middle = zhdr->first_chunks + ZHDR_CHUNKS;
1071 }
1072 add_to_unbuddied(pool, zhdr);
1073
1074headless:
1075 spin_lock(&pool->lock);
1076 /* Add/move z3fold page to beginning of LRU */
1077 if (!list_empty(&page->lru))
1078 list_del(&page->lru);
1079
1080 list_add(&page->lru, &pool->lru);
1081
1082 *handle = encode_handle(zhdr, bud);
1083 spin_unlock(&pool->lock);
1084 if (bud != HEADLESS)
1085 z3fold_page_unlock(zhdr);
1086
1087 return 0;
1088}
1089
1090/**
1091 * z3fold_free() - frees the allocation associated with the given handle
1092 * @pool: pool in which the allocation resided
1093 * @handle: handle associated with the allocation returned by z3fold_alloc()
1094 *
1095 * In the case that the z3fold page in which the allocation resides is under
1096 * reclaim, as indicated by the PAGE_CLAIMED flag being set, this function
1097 * only sets the first|middle|last_chunks to 0. The page is actually freed
1098 * once all buddies are evicted (see z3fold_reclaim_page() below).
1099 */
1100static void z3fold_free(struct z3fold_pool *pool, unsigned long handle)
1101{
1102 struct z3fold_header *zhdr;
1103 struct page *page;
1104 enum buddy bud;
1105 bool page_claimed;
1106
1107 zhdr = get_z3fold_header(handle);
1108 page = virt_to_page(zhdr);
1109 page_claimed = test_and_set_bit(PAGE_CLAIMED, &page->private);
1110
1111 if (test_bit(PAGE_HEADLESS, &page->private)) {
1112 /* if a headless page is under reclaim, just leave.
1113 * NB: we use test_and_set_bit for a reason: if the bit
1114 * has not been set before, we release this page
1115 * immediately so we don't care about its value any more.
1116 */
1117 if (!page_claimed) {
1118 spin_lock(&pool->lock);
1119 list_del(&page->lru);
1120 spin_unlock(&pool->lock);
1121 put_z3fold_header(zhdr);
1122 free_z3fold_page(page, true);
1123 atomic64_dec(&pool->pages_nr);
1124 }
1125 return;
1126 }
1127
1128 /* Non-headless case */
1129 bud = handle_to_buddy(handle);
1130
1131 switch (bud) {
1132 case FIRST:
1133 zhdr->first_chunks = 0;
1134 break;
1135 case MIDDLE:
1136 zhdr->middle_chunks = 0;
1137 break;
1138 case LAST:
1139 zhdr->last_chunks = 0;
1140 break;
1141 default:
1142 pr_err("%s: unknown bud %d\n", __func__, bud);
1143 WARN_ON(1);
1144 put_z3fold_header(zhdr);
1145 return;
1146 }
1147
1148 if (!page_claimed)
1149 free_handle(handle, zhdr);
1150 if (kref_put(&zhdr->refcount, release_z3fold_page_locked_list))
1151 return;
1152 if (page_claimed) {
1153 /* the page has not been claimed by us */
1154 put_z3fold_header(zhdr);
1155 return;
1156 }
1157 if (test_and_set_bit(NEEDS_COMPACTING, &page->private)) {
1158 clear_bit(PAGE_CLAIMED, &page->private);
1159 put_z3fold_header(zhdr);
1160 return;
1161 }
1162 if (zhdr->cpu < 0 || !cpu_online(zhdr->cpu)) {
1163 zhdr->cpu = -1;
1164 kref_get(&zhdr->refcount);
1165 clear_bit(PAGE_CLAIMED, &page->private);
1166 do_compact_page(zhdr, true);
1167 return;
1168 }
1169 kref_get(&zhdr->refcount);
1170 clear_bit(PAGE_CLAIMED, &page->private);
1171 queue_work_on(zhdr->cpu, pool->compact_wq, &zhdr->work);
1172 put_z3fold_header(zhdr);
1173}
1174
1175/**
1176 * z3fold_reclaim_page() - evicts allocations from a pool page and frees it
1177 * @pool: pool from which a page will attempt to be evicted
1178 * @retries: number of pages on the LRU list for which eviction will
1179 * be attempted before failing
1180 *
1181 * z3fold reclaim is different from normal system reclaim in that it is done
1182 * from the bottom, up. This is because only the bottom layer, z3fold, has
1183 * information on how the allocations are organized within each z3fold page.
1184 * This has the potential to create interesting locking situations between
1185 * z3fold and the user, however.
1186 *
1187 * To avoid these, this is how z3fold_reclaim_page() should be called:
1188 *
1189 * The user detects a page should be reclaimed and calls z3fold_reclaim_page().
1190 * z3fold_reclaim_page() will remove a z3fold page from the pool LRU list and
1191 * call the user-defined eviction handler with the pool and handle as
1192 * arguments.
1193 *
1194 * If the handle can not be evicted, the eviction handler should return
1195 * non-zero. z3fold_reclaim_page() will add the z3fold page back to the
1196 * appropriate list and try the next z3fold page on the LRU up to
1197 * a user defined number of retries.
1198 *
1199 * If the handle is successfully evicted, the eviction handler should
1200 * return 0 _and_ should have called z3fold_free() on the handle. z3fold_free()
1201 * contains logic to delay freeing the page if the page is under reclaim,
1202 * as indicated by the setting of the PG_reclaim flag on the underlying page.
1203 *
1204 * If all buddies in the z3fold page are successfully evicted, then the
1205 * z3fold page can be freed.
1206 *
1207 * Returns: 0 if page is successfully freed, otherwise -EINVAL if there are
1208 * no pages to evict or an eviction handler is not registered, -EAGAIN if
1209 * the retry limit was hit.
1210 */
1211static int z3fold_reclaim_page(struct z3fold_pool *pool, unsigned int retries)
1212{
1213 int i, ret = -1;
1214 struct z3fold_header *zhdr = NULL;
1215 struct page *page = NULL;
1216 struct list_head *pos;
1217 unsigned long first_handle = 0, middle_handle = 0, last_handle = 0;
1218 struct z3fold_buddy_slots slots __attribute__((aligned(SLOTS_ALIGN)));
1219
1220 rwlock_init(&slots.lock);
1221 slots.pool = (unsigned long)pool | (1 << HANDLES_NOFREE);
1222
1223 spin_lock(&pool->lock);
1224 for (i = 0; i < retries; i++) {
1225 if (list_empty(&pool->lru)) {
1226 spin_unlock(&pool->lock);
1227 return -EINVAL;
1228 }
1229 list_for_each_prev(pos, &pool->lru) {
1230 page = list_entry(pos, struct page, lru);
1231
1232 zhdr = page_address(page);
1233 if (test_bit(PAGE_HEADLESS, &page->private)) {
1234 /*
1235 * For non-headless pages, we wait to do this
1236 * until we have the page lock to avoid racing
1237 * with __z3fold_alloc(). Headless pages don't
1238 * have a lock (and __z3fold_alloc() will never
1239 * see them), but we still need to test and set
1240 * PAGE_CLAIMED to avoid racing with
1241 * z3fold_free(), so just do it now before
1242 * leaving the loop.
1243 */
1244 if (test_and_set_bit(PAGE_CLAIMED, &page->private))
1245 continue;
1246
1247 break;
1248 }
1249
1250 if (!z3fold_page_trylock(zhdr)) {
1251 zhdr = NULL;
1252 continue; /* can't evict at this point */
1253 }
1254
1255 /* test_and_set_bit is of course atomic, but we still
1256 * need to do it under page lock, otherwise checking
1257 * that bit in __z3fold_alloc wouldn't make sense
1258 */
1259 if (zhdr->foreign_handles ||
1260 test_and_set_bit(PAGE_CLAIMED, &page->private)) {
1261 z3fold_page_unlock(zhdr);
1262 zhdr = NULL;
1263 continue; /* can't evict such page */
1264 }
1265 list_del_init(&zhdr->buddy);
1266 zhdr->cpu = -1;
1267 /* See comment in __z3fold_alloc. */
1268 kref_get(&zhdr->refcount);
1269 break;
1270 }
1271
1272 if (!zhdr)
1273 break;
1274
1275 list_del_init(&page->lru);
1276 spin_unlock(&pool->lock);
1277
1278 if (!test_bit(PAGE_HEADLESS, &page->private)) {
1279 /*
1280 * We need encode the handles before unlocking, and
1281 * use our local slots structure because z3fold_free
1282 * can zero out zhdr->slots and we can't do much
1283 * about that
1284 */
1285 first_handle = 0;
1286 last_handle = 0;
1287 middle_handle = 0;
1288 memset(slots.slot, 0, sizeof(slots.slot));
1289 if (zhdr->first_chunks)
1290 first_handle = __encode_handle(zhdr, &slots,
1291 FIRST);
1292 if (zhdr->middle_chunks)
1293 middle_handle = __encode_handle(zhdr, &slots,
1294 MIDDLE);
1295 if (zhdr->last_chunks)
1296 last_handle = __encode_handle(zhdr, &slots,
1297 LAST);
1298 /*
1299 * it's safe to unlock here because we hold a
1300 * reference to this page
1301 */
1302 z3fold_page_unlock(zhdr);
1303 } else {
1304 first_handle = encode_handle(zhdr, HEADLESS);
1305 last_handle = middle_handle = 0;
1306 }
1307 /* Issue the eviction callback(s) */
1308 if (middle_handle) {
1309 ret = pool->zpool_ops->evict(pool->zpool, middle_handle);
1310 if (ret)
1311 goto next;
1312 }
1313 if (first_handle) {
1314 ret = pool->zpool_ops->evict(pool->zpool, first_handle);
1315 if (ret)
1316 goto next;
1317 }
1318 if (last_handle) {
1319 ret = pool->zpool_ops->evict(pool->zpool, last_handle);
1320 if (ret)
1321 goto next;
1322 }
1323next:
1324 if (test_bit(PAGE_HEADLESS, &page->private)) {
1325 if (ret == 0) {
1326 free_z3fold_page(page, true);
1327 atomic64_dec(&pool->pages_nr);
1328 return 0;
1329 }
1330 spin_lock(&pool->lock);
1331 list_add(&page->lru, &pool->lru);
1332 spin_unlock(&pool->lock);
1333 clear_bit(PAGE_CLAIMED, &page->private);
1334 } else {
1335 struct z3fold_buddy_slots *slots = zhdr->slots;
1336 z3fold_page_lock(zhdr);
1337 if (kref_put(&zhdr->refcount,
1338 release_z3fold_page_locked)) {
1339 kmem_cache_free(pool->c_handle, slots);
1340 return 0;
1341 }
1342 /*
1343 * if we are here, the page is still not completely
1344 * free. Take the global pool lock then to be able
1345 * to add it back to the lru list
1346 */
1347 spin_lock(&pool->lock);
1348 list_add(&page->lru, &pool->lru);
1349 spin_unlock(&pool->lock);
1350 if (list_empty(&zhdr->buddy))
1351 add_to_unbuddied(pool, zhdr);
1352 clear_bit(PAGE_CLAIMED, &page->private);
1353 z3fold_page_unlock(zhdr);
1354 }
1355
1356 /* We started off locked to we need to lock the pool back */
1357 spin_lock(&pool->lock);
1358 }
1359 spin_unlock(&pool->lock);
1360 return -EAGAIN;
1361}
1362
1363/**
1364 * z3fold_map() - maps the allocation associated with the given handle
1365 * @pool: pool in which the allocation resides
1366 * @handle: handle associated with the allocation to be mapped
1367 *
1368 * Extracts the buddy number from handle and constructs the pointer to the
1369 * correct starting chunk within the page.
1370 *
1371 * Returns: a pointer to the mapped allocation
1372 */
1373static void *z3fold_map(struct z3fold_pool *pool, unsigned long handle)
1374{
1375 struct z3fold_header *zhdr;
1376 struct page *page;
1377 void *addr;
1378 enum buddy buddy;
1379
1380 zhdr = get_z3fold_header(handle);
1381 addr = zhdr;
1382 page = virt_to_page(zhdr);
1383
1384 if (test_bit(PAGE_HEADLESS, &page->private))
1385 goto out;
1386
1387 buddy = handle_to_buddy(handle);
1388 switch (buddy) {
1389 case FIRST:
1390 addr += ZHDR_SIZE_ALIGNED;
1391 break;
1392 case MIDDLE:
1393 addr += zhdr->start_middle << CHUNK_SHIFT;
1394 set_bit(MIDDLE_CHUNK_MAPPED, &page->private);
1395 break;
1396 case LAST:
1397 addr += PAGE_SIZE - (handle_to_chunks(handle) << CHUNK_SHIFT);
1398 break;
1399 default:
1400 pr_err("unknown buddy id %d\n", buddy);
1401 WARN_ON(1);
1402 addr = NULL;
1403 break;
1404 }
1405
1406 if (addr)
1407 zhdr->mapped_count++;
1408out:
1409 put_z3fold_header(zhdr);
1410 return addr;
1411}
1412
1413/**
1414 * z3fold_unmap() - unmaps the allocation associated with the given handle
1415 * @pool: pool in which the allocation resides
1416 * @handle: handle associated with the allocation to be unmapped
1417 */
1418static void z3fold_unmap(struct z3fold_pool *pool, unsigned long handle)
1419{
1420 struct z3fold_header *zhdr;
1421 struct page *page;
1422 enum buddy buddy;
1423
1424 zhdr = get_z3fold_header(handle);
1425 page = virt_to_page(zhdr);
1426
1427 if (test_bit(PAGE_HEADLESS, &page->private))
1428 return;
1429
1430 buddy = handle_to_buddy(handle);
1431 if (buddy == MIDDLE)
1432 clear_bit(MIDDLE_CHUNK_MAPPED, &page->private);
1433 zhdr->mapped_count--;
1434 put_z3fold_header(zhdr);
1435}
1436
1437/**
1438 * z3fold_get_pool_size() - gets the z3fold pool size in pages
1439 * @pool: pool whose size is being queried
1440 *
1441 * Returns: size in pages of the given pool.
1442 */
1443static u64 z3fold_get_pool_size(struct z3fold_pool *pool)
1444{
1445 return atomic64_read(&pool->pages_nr);
1446}
1447
1448static bool z3fold_page_isolate(struct page *page, isolate_mode_t mode)
1449{
1450 struct z3fold_header *zhdr;
1451 struct z3fold_pool *pool;
1452
1453 VM_BUG_ON_PAGE(!PageMovable(page), page);
1454 VM_BUG_ON_PAGE(PageIsolated(page), page);
1455
1456 if (test_bit(PAGE_HEADLESS, &page->private))
1457 return false;
1458
1459 zhdr = page_address(page);
1460 z3fold_page_lock(zhdr);
1461 if (test_bit(NEEDS_COMPACTING, &page->private) ||
1462 test_bit(PAGE_STALE, &page->private))
1463 goto out;
1464
1465 if (zhdr->mapped_count != 0 || zhdr->foreign_handles != 0)
1466 goto out;
1467
1468 if (test_and_set_bit(PAGE_CLAIMED, &page->private))
1469 goto out;
1470 pool = zhdr_to_pool(zhdr);
1471 spin_lock(&pool->lock);
1472 if (!list_empty(&zhdr->buddy))
1473 list_del_init(&zhdr->buddy);
1474 if (!list_empty(&page->lru))
1475 list_del_init(&page->lru);
1476 spin_unlock(&pool->lock);
1477
1478 kref_get(&zhdr->refcount);
1479 z3fold_page_unlock(zhdr);
1480 return true;
1481
1482out:
1483 z3fold_page_unlock(zhdr);
1484 return false;
1485}
1486
1487static int z3fold_page_migrate(struct page *newpage, struct page *page,
1488 enum migrate_mode mode)
1489{
1490 struct z3fold_header *zhdr, *new_zhdr;
1491 struct z3fold_pool *pool;
1492
1493 VM_BUG_ON_PAGE(!PageMovable(page), page);
1494 VM_BUG_ON_PAGE(!PageIsolated(page), page);
1495 VM_BUG_ON_PAGE(!test_bit(PAGE_CLAIMED, &page->private), page);
1496 VM_BUG_ON_PAGE(!PageLocked(newpage), newpage);
1497
1498 zhdr = page_address(page);
1499 pool = zhdr_to_pool(zhdr);
1500
1501 if (!z3fold_page_trylock(zhdr))
1502 return -EAGAIN;
1503 if (zhdr->mapped_count != 0 || zhdr->foreign_handles != 0) {
1504 clear_bit(PAGE_CLAIMED, &page->private);
1505 z3fold_page_unlock(zhdr);
1506 return -EBUSY;
1507 }
1508 if (work_pending(&zhdr->work)) {
1509 z3fold_page_unlock(zhdr);
1510 return -EAGAIN;
1511 }
1512 new_zhdr = page_address(newpage);
1513 memcpy(new_zhdr, zhdr, PAGE_SIZE);
1514 newpage->private = page->private;
1515 set_bit(PAGE_MIGRATED, &page->private);
1516 z3fold_page_unlock(zhdr);
1517 spin_lock_init(&new_zhdr->page_lock);
1518 INIT_WORK(&new_zhdr->work, compact_page_work);
1519 /*
1520 * z3fold_page_isolate() ensures that new_zhdr->buddy is empty,
1521 * so we only have to reinitialize it.
1522 */
1523 INIT_LIST_HEAD(&new_zhdr->buddy);
1524 __ClearPageMovable(page);
1525
1526 get_page(newpage);
1527 z3fold_page_lock(new_zhdr);
1528 if (new_zhdr->first_chunks)
1529 encode_handle(new_zhdr, FIRST);
1530 if (new_zhdr->last_chunks)
1531 encode_handle(new_zhdr, LAST);
1532 if (new_zhdr->middle_chunks)
1533 encode_handle(new_zhdr, MIDDLE);
1534 set_bit(NEEDS_COMPACTING, &newpage->private);
1535 new_zhdr->cpu = smp_processor_id();
1536 spin_lock(&pool->lock);
1537 list_add(&newpage->lru, &pool->lru);
1538 spin_unlock(&pool->lock);
1539 __SetPageMovable(newpage, &z3fold_mops);
1540 z3fold_page_unlock(new_zhdr);
1541
1542 queue_work_on(new_zhdr->cpu, pool->compact_wq, &new_zhdr->work);
1543
1544 /* PAGE_CLAIMED and PAGE_MIGRATED are cleared now. */
1545 page->private = 0;
1546 put_page(page);
1547 return 0;
1548}
1549
1550static void z3fold_page_putback(struct page *page)
1551{
1552 struct z3fold_header *zhdr;
1553 struct z3fold_pool *pool;
1554
1555 zhdr = page_address(page);
1556 pool = zhdr_to_pool(zhdr);
1557
1558 z3fold_page_lock(zhdr);
1559 if (!list_empty(&zhdr->buddy))
1560 list_del_init(&zhdr->buddy);
1561 INIT_LIST_HEAD(&page->lru);
1562 if (kref_put(&zhdr->refcount, release_z3fold_page_locked))
1563 return;
1564 spin_lock(&pool->lock);
1565 list_add(&page->lru, &pool->lru);
1566 spin_unlock(&pool->lock);
1567 if (list_empty(&zhdr->buddy))
1568 add_to_unbuddied(pool, zhdr);
1569 clear_bit(PAGE_CLAIMED, &page->private);
1570 z3fold_page_unlock(zhdr);
1571}
1572
1573static const struct movable_operations z3fold_mops = {
1574 .isolate_page = z3fold_page_isolate,
1575 .migrate_page = z3fold_page_migrate,
1576 .putback_page = z3fold_page_putback,
1577};
1578
1579/*****************
1580 * zpool
1581 ****************/
1582
1583static void *z3fold_zpool_create(const char *name, gfp_t gfp,
1584 const struct zpool_ops *zpool_ops,
1585 struct zpool *zpool)
1586{
1587 struct z3fold_pool *pool;
1588
1589 pool = z3fold_create_pool(name, gfp);
1590 if (pool) {
1591 pool->zpool = zpool;
1592 pool->zpool_ops = zpool_ops;
1593 }
1594 return pool;
1595}
1596
1597static void z3fold_zpool_destroy(void *pool)
1598{
1599 z3fold_destroy_pool(pool);
1600}
1601
1602static int z3fold_zpool_malloc(void *pool, size_t size, gfp_t gfp,
1603 unsigned long *handle)
1604{
1605 return z3fold_alloc(pool, size, gfp, handle);
1606}
1607static void z3fold_zpool_free(void *pool, unsigned long handle)
1608{
1609 z3fold_free(pool, handle);
1610}
1611
1612static int z3fold_zpool_shrink(void *pool, unsigned int pages,
1613 unsigned int *reclaimed)
1614{
1615 unsigned int total = 0;
1616 int ret = -EINVAL;
1617
1618 while (total < pages) {
1619 ret = z3fold_reclaim_page(pool, 8);
1620 if (ret < 0)
1621 break;
1622 total++;
1623 }
1624
1625 if (reclaimed)
1626 *reclaimed = total;
1627
1628 return ret;
1629}
1630
1631static void *z3fold_zpool_map(void *pool, unsigned long handle,
1632 enum zpool_mapmode mm)
1633{
1634 return z3fold_map(pool, handle);
1635}
1636static void z3fold_zpool_unmap(void *pool, unsigned long handle)
1637{
1638 z3fold_unmap(pool, handle);
1639}
1640
1641static u64 z3fold_zpool_total_size(void *pool)
1642{
1643 return z3fold_get_pool_size(pool) * PAGE_SIZE;
1644}
1645
1646static struct zpool_driver z3fold_zpool_driver = {
1647 .type = "z3fold",
1648 .sleep_mapped = true,
1649 .owner = THIS_MODULE,
1650 .create = z3fold_zpool_create,
1651 .destroy = z3fold_zpool_destroy,
1652 .malloc = z3fold_zpool_malloc,
1653 .free = z3fold_zpool_free,
1654 .shrink = z3fold_zpool_shrink,
1655 .map = z3fold_zpool_map,
1656 .unmap = z3fold_zpool_unmap,
1657 .total_size = z3fold_zpool_total_size,
1658};
1659
1660MODULE_ALIAS("zpool-z3fold");
1661
1662static int __init init_z3fold(void)
1663{
1664 /*
1665 * Make sure the z3fold header is not larger than the page size and
1666 * there has remaining spaces for its buddy.
1667 */
1668 BUILD_BUG_ON(ZHDR_SIZE_ALIGNED > PAGE_SIZE - CHUNK_SIZE);
1669 zpool_register_driver(&z3fold_zpool_driver);
1670
1671 return 0;
1672}
1673
1674static void __exit exit_z3fold(void)
1675{
1676 zpool_unregister_driver(&z3fold_zpool_driver);
1677}
1678
1679module_init(init_z3fold);
1680module_exit(exit_z3fold);
1681
1682MODULE_LICENSE("GPL");
1683MODULE_AUTHOR("Vitaly Wool <vitalywool@gmail.com>");
1684MODULE_DESCRIPTION("3-Fold Allocator for Compressed Pages");
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * z3fold.c
4 *
5 * Author: Vitaly Wool <vitaly.wool@konsulko.com>
6 * Copyright (C) 2016, Sony Mobile Communications Inc.
7 *
8 * This implementation is based on zbud written by Seth Jennings.
9 *
10 * z3fold is an special purpose allocator for storing compressed pages. It
11 * can store up to three compressed pages per page which improves the
12 * compression ratio of zbud while retaining its main concepts (e. g. always
13 * storing an integral number of objects per page) and simplicity.
14 * It still has simple and deterministic reclaim properties that make it
15 * preferable to a higher density approach (with no requirement on integral
16 * number of object per page) when reclaim is used.
17 *
18 * As in zbud, pages are divided into "chunks". The size of the chunks is
19 * fixed at compile time and is determined by NCHUNKS_ORDER below.
20 *
21 * z3fold doesn't export any API and is meant to be used via zpool API.
22 */
23
24#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
25
26#include <linux/atomic.h>
27#include <linux/sched.h>
28#include <linux/cpumask.h>
29#include <linux/list.h>
30#include <linux/mm.h>
31#include <linux/module.h>
32#include <linux/page-flags.h>
33#include <linux/migrate.h>
34#include <linux/node.h>
35#include <linux/compaction.h>
36#include <linux/percpu.h>
37#include <linux/mount.h>
38#include <linux/pseudo_fs.h>
39#include <linux/fs.h>
40#include <linux/preempt.h>
41#include <linux/workqueue.h>
42#include <linux/slab.h>
43#include <linux/spinlock.h>
44#include <linux/zpool.h>
45#include <linux/magic.h>
46#include <linux/kmemleak.h>
47
48/*
49 * NCHUNKS_ORDER determines the internal allocation granularity, effectively
50 * adjusting internal fragmentation. It also determines the number of
51 * freelists maintained in each pool. NCHUNKS_ORDER of 6 means that the
52 * allocation granularity will be in chunks of size PAGE_SIZE/64. Some chunks
53 * in the beginning of an allocated page are occupied by z3fold header, so
54 * NCHUNKS will be calculated to 63 (or 62 in case CONFIG_DEBUG_SPINLOCK=y),
55 * which shows the max number of free chunks in z3fold page, also there will
56 * be 63, or 62, respectively, freelists per pool.
57 */
58#define NCHUNKS_ORDER 6
59
60#define CHUNK_SHIFT (PAGE_SHIFT - NCHUNKS_ORDER)
61#define CHUNK_SIZE (1 << CHUNK_SHIFT)
62#define ZHDR_SIZE_ALIGNED round_up(sizeof(struct z3fold_header), CHUNK_SIZE)
63#define ZHDR_CHUNKS (ZHDR_SIZE_ALIGNED >> CHUNK_SHIFT)
64#define TOTAL_CHUNKS (PAGE_SIZE >> CHUNK_SHIFT)
65#define NCHUNKS ((PAGE_SIZE - ZHDR_SIZE_ALIGNED) >> CHUNK_SHIFT)
66
67#define BUDDY_MASK (0x3)
68#define BUDDY_SHIFT 2
69#define SLOTS_ALIGN (0x40)
70
71/*****************
72 * Structures
73*****************/
74struct z3fold_pool;
75struct z3fold_ops {
76 int (*evict)(struct z3fold_pool *pool, unsigned long handle);
77};
78
79enum buddy {
80 HEADLESS = 0,
81 FIRST,
82 MIDDLE,
83 LAST,
84 BUDDIES_MAX = LAST
85};
86
87struct z3fold_buddy_slots {
88 /*
89 * we are using BUDDY_MASK in handle_to_buddy etc. so there should
90 * be enough slots to hold all possible variants
91 */
92 unsigned long slot[BUDDY_MASK + 1];
93 unsigned long pool; /* back link + flags */
94 rwlock_t lock;
95};
96#define HANDLE_FLAG_MASK (0x03)
97
98/*
99 * struct z3fold_header - z3fold page metadata occupying first chunks of each
100 * z3fold page, except for HEADLESS pages
101 * @buddy: links the z3fold page into the relevant list in the
102 * pool
103 * @page_lock: per-page lock
104 * @refcount: reference count for the z3fold page
105 * @work: work_struct for page layout optimization
106 * @slots: pointer to the structure holding buddy slots
107 * @pool: pointer to the containing pool
108 * @cpu: CPU which this page "belongs" to
109 * @first_chunks: the size of the first buddy in chunks, 0 if free
110 * @middle_chunks: the size of the middle buddy in chunks, 0 if free
111 * @last_chunks: the size of the last buddy in chunks, 0 if free
112 * @first_num: the starting number (for the first handle)
113 * @mapped_count: the number of objects currently mapped
114 */
115struct z3fold_header {
116 struct list_head buddy;
117 spinlock_t page_lock;
118 struct kref refcount;
119 struct work_struct work;
120 struct z3fold_buddy_slots *slots;
121 struct z3fold_pool *pool;
122 short cpu;
123 unsigned short first_chunks;
124 unsigned short middle_chunks;
125 unsigned short last_chunks;
126 unsigned short start_middle;
127 unsigned short first_num:2;
128 unsigned short mapped_count:2;
129 unsigned short foreign_handles:2;
130};
131
132/**
133 * struct z3fold_pool - stores metadata for each z3fold pool
134 * @name: pool name
135 * @lock: protects pool unbuddied/lru lists
136 * @stale_lock: protects pool stale page list
137 * @unbuddied: per-cpu array of lists tracking z3fold pages that contain 2-
138 * buddies; the list each z3fold page is added to depends on
139 * the size of its free region.
140 * @lru: list tracking the z3fold pages in LRU order by most recently
141 * added buddy.
142 * @stale: list of pages marked for freeing
143 * @pages_nr: number of z3fold pages in the pool.
144 * @c_handle: cache for z3fold_buddy_slots allocation
145 * @ops: pointer to a structure of user defined operations specified at
146 * pool creation time.
147 * @compact_wq: workqueue for page layout background optimization
148 * @release_wq: workqueue for safe page release
149 * @work: work_struct for safe page release
150 * @inode: inode for z3fold pseudo filesystem
151 *
152 * This structure is allocated at pool creation time and maintains metadata
153 * pertaining to a particular z3fold pool.
154 */
155struct z3fold_pool {
156 const char *name;
157 spinlock_t lock;
158 spinlock_t stale_lock;
159 struct list_head *unbuddied;
160 struct list_head lru;
161 struct list_head stale;
162 atomic64_t pages_nr;
163 struct kmem_cache *c_handle;
164 const struct z3fold_ops *ops;
165 struct zpool *zpool;
166 const struct zpool_ops *zpool_ops;
167 struct workqueue_struct *compact_wq;
168 struct workqueue_struct *release_wq;
169 struct work_struct work;
170 struct inode *inode;
171};
172
173/*
174 * Internal z3fold page flags
175 */
176enum z3fold_page_flags {
177 PAGE_HEADLESS = 0,
178 MIDDLE_CHUNK_MAPPED,
179 NEEDS_COMPACTING,
180 PAGE_STALE,
181 PAGE_CLAIMED, /* by either reclaim or free */
182};
183
184/*
185 * handle flags, go under HANDLE_FLAG_MASK
186 */
187enum z3fold_handle_flags {
188 HANDLES_ORPHANED = 0,
189};
190
191/*
192 * Forward declarations
193 */
194static struct z3fold_header *__z3fold_alloc(struct z3fold_pool *, size_t, bool);
195static void compact_page_work(struct work_struct *w);
196
197/*****************
198 * Helpers
199*****************/
200
201/* Converts an allocation size in bytes to size in z3fold chunks */
202static int size_to_chunks(size_t size)
203{
204 return (size + CHUNK_SIZE - 1) >> CHUNK_SHIFT;
205}
206
207#define for_each_unbuddied_list(_iter, _begin) \
208 for ((_iter) = (_begin); (_iter) < NCHUNKS; (_iter)++)
209
210static inline struct z3fold_buddy_slots *alloc_slots(struct z3fold_pool *pool,
211 gfp_t gfp)
212{
213 struct z3fold_buddy_slots *slots;
214
215 slots = kmem_cache_alloc(pool->c_handle,
216 (gfp & ~(__GFP_HIGHMEM | __GFP_MOVABLE)));
217
218 if (slots) {
219 /* It will be freed separately in free_handle(). */
220 kmemleak_not_leak(slots);
221 memset(slots->slot, 0, sizeof(slots->slot));
222 slots->pool = (unsigned long)pool;
223 rwlock_init(&slots->lock);
224 }
225
226 return slots;
227}
228
229static inline struct z3fold_pool *slots_to_pool(struct z3fold_buddy_slots *s)
230{
231 return (struct z3fold_pool *)(s->pool & ~HANDLE_FLAG_MASK);
232}
233
234static inline struct z3fold_buddy_slots *handle_to_slots(unsigned long handle)
235{
236 return (struct z3fold_buddy_slots *)(handle & ~(SLOTS_ALIGN - 1));
237}
238
239/* Lock a z3fold page */
240static inline void z3fold_page_lock(struct z3fold_header *zhdr)
241{
242 spin_lock(&zhdr->page_lock);
243}
244
245/* Try to lock a z3fold page */
246static inline int z3fold_page_trylock(struct z3fold_header *zhdr)
247{
248 return spin_trylock(&zhdr->page_lock);
249}
250
251/* Unlock a z3fold page */
252static inline void z3fold_page_unlock(struct z3fold_header *zhdr)
253{
254 spin_unlock(&zhdr->page_lock);
255}
256
257
258static inline struct z3fold_header *__get_z3fold_header(unsigned long handle,
259 bool lock)
260{
261 struct z3fold_buddy_slots *slots;
262 struct z3fold_header *zhdr;
263 int locked = 0;
264
265 if (!(handle & (1 << PAGE_HEADLESS))) {
266 slots = handle_to_slots(handle);
267 do {
268 unsigned long addr;
269
270 read_lock(&slots->lock);
271 addr = *(unsigned long *)handle;
272 zhdr = (struct z3fold_header *)(addr & PAGE_MASK);
273 if (lock)
274 locked = z3fold_page_trylock(zhdr);
275 read_unlock(&slots->lock);
276 if (locked)
277 break;
278 cpu_relax();
279 } while (lock);
280 } else {
281 zhdr = (struct z3fold_header *)(handle & PAGE_MASK);
282 }
283
284 return zhdr;
285}
286
287/* Returns the z3fold page where a given handle is stored */
288static inline struct z3fold_header *handle_to_z3fold_header(unsigned long h)
289{
290 return __get_z3fold_header(h, false);
291}
292
293/* return locked z3fold page if it's not headless */
294static inline struct z3fold_header *get_z3fold_header(unsigned long h)
295{
296 return __get_z3fold_header(h, true);
297}
298
299static inline void put_z3fold_header(struct z3fold_header *zhdr)
300{
301 struct page *page = virt_to_page(zhdr);
302
303 if (!test_bit(PAGE_HEADLESS, &page->private))
304 z3fold_page_unlock(zhdr);
305}
306
307static inline void free_handle(unsigned long handle)
308{
309 struct z3fold_buddy_slots *slots;
310 struct z3fold_header *zhdr;
311 int i;
312 bool is_free;
313
314 if (handle & (1 << PAGE_HEADLESS))
315 return;
316
317 if (WARN_ON(*(unsigned long *)handle == 0))
318 return;
319
320 zhdr = handle_to_z3fold_header(handle);
321 slots = handle_to_slots(handle);
322 write_lock(&slots->lock);
323 *(unsigned long *)handle = 0;
324 if (zhdr->slots == slots) {
325 write_unlock(&slots->lock);
326 return; /* simple case, nothing else to do */
327 }
328
329 /* we are freeing a foreign handle if we are here */
330 zhdr->foreign_handles--;
331 is_free = true;
332 if (!test_bit(HANDLES_ORPHANED, &slots->pool)) {
333 write_unlock(&slots->lock);
334 return;
335 }
336 for (i = 0; i <= BUDDY_MASK; i++) {
337 if (slots->slot[i]) {
338 is_free = false;
339 break;
340 }
341 }
342 write_unlock(&slots->lock);
343
344 if (is_free) {
345 struct z3fold_pool *pool = slots_to_pool(slots);
346
347 kmem_cache_free(pool->c_handle, slots);
348 }
349}
350
351static int z3fold_init_fs_context(struct fs_context *fc)
352{
353 return init_pseudo(fc, Z3FOLD_MAGIC) ? 0 : -ENOMEM;
354}
355
356static struct file_system_type z3fold_fs = {
357 .name = "z3fold",
358 .init_fs_context = z3fold_init_fs_context,
359 .kill_sb = kill_anon_super,
360};
361
362static struct vfsmount *z3fold_mnt;
363static int z3fold_mount(void)
364{
365 int ret = 0;
366
367 z3fold_mnt = kern_mount(&z3fold_fs);
368 if (IS_ERR(z3fold_mnt))
369 ret = PTR_ERR(z3fold_mnt);
370
371 return ret;
372}
373
374static void z3fold_unmount(void)
375{
376 kern_unmount(z3fold_mnt);
377}
378
379static const struct address_space_operations z3fold_aops;
380static int z3fold_register_migration(struct z3fold_pool *pool)
381{
382 pool->inode = alloc_anon_inode(z3fold_mnt->mnt_sb);
383 if (IS_ERR(pool->inode)) {
384 pool->inode = NULL;
385 return 1;
386 }
387
388 pool->inode->i_mapping->private_data = pool;
389 pool->inode->i_mapping->a_ops = &z3fold_aops;
390 return 0;
391}
392
393static void z3fold_unregister_migration(struct z3fold_pool *pool)
394{
395 if (pool->inode)
396 iput(pool->inode);
397 }
398
399/* Initializes the z3fold header of a newly allocated z3fold page */
400static struct z3fold_header *init_z3fold_page(struct page *page, bool headless,
401 struct z3fold_pool *pool, gfp_t gfp)
402{
403 struct z3fold_header *zhdr = page_address(page);
404 struct z3fold_buddy_slots *slots;
405
406 INIT_LIST_HEAD(&page->lru);
407 clear_bit(PAGE_HEADLESS, &page->private);
408 clear_bit(MIDDLE_CHUNK_MAPPED, &page->private);
409 clear_bit(NEEDS_COMPACTING, &page->private);
410 clear_bit(PAGE_STALE, &page->private);
411 clear_bit(PAGE_CLAIMED, &page->private);
412 if (headless)
413 return zhdr;
414
415 slots = alloc_slots(pool, gfp);
416 if (!slots)
417 return NULL;
418
419 spin_lock_init(&zhdr->page_lock);
420 kref_init(&zhdr->refcount);
421 zhdr->first_chunks = 0;
422 zhdr->middle_chunks = 0;
423 zhdr->last_chunks = 0;
424 zhdr->first_num = 0;
425 zhdr->start_middle = 0;
426 zhdr->cpu = -1;
427 zhdr->foreign_handles = 0;
428 zhdr->mapped_count = 0;
429 zhdr->slots = slots;
430 zhdr->pool = pool;
431 INIT_LIST_HEAD(&zhdr->buddy);
432 INIT_WORK(&zhdr->work, compact_page_work);
433 return zhdr;
434}
435
436/* Resets the struct page fields and frees the page */
437static void free_z3fold_page(struct page *page, bool headless)
438{
439 if (!headless) {
440 lock_page(page);
441 __ClearPageMovable(page);
442 unlock_page(page);
443 }
444 ClearPagePrivate(page);
445 __free_page(page);
446}
447
448/* Helper function to build the index */
449static inline int __idx(struct z3fold_header *zhdr, enum buddy bud)
450{
451 return (bud + zhdr->first_num) & BUDDY_MASK;
452}
453
454/*
455 * Encodes the handle of a particular buddy within a z3fold page
456 * Pool lock should be held as this function accesses first_num
457 */
458static unsigned long __encode_handle(struct z3fold_header *zhdr,
459 struct z3fold_buddy_slots *slots,
460 enum buddy bud)
461{
462 unsigned long h = (unsigned long)zhdr;
463 int idx = 0;
464
465 /*
466 * For a headless page, its handle is its pointer with the extra
467 * PAGE_HEADLESS bit set
468 */
469 if (bud == HEADLESS)
470 return h | (1 << PAGE_HEADLESS);
471
472 /* otherwise, return pointer to encoded handle */
473 idx = __idx(zhdr, bud);
474 h += idx;
475 if (bud == LAST)
476 h |= (zhdr->last_chunks << BUDDY_SHIFT);
477
478 write_lock(&slots->lock);
479 slots->slot[idx] = h;
480 write_unlock(&slots->lock);
481 return (unsigned long)&slots->slot[idx];
482}
483
484static unsigned long encode_handle(struct z3fold_header *zhdr, enum buddy bud)
485{
486 return __encode_handle(zhdr, zhdr->slots, bud);
487}
488
489/* only for LAST bud, returns zero otherwise */
490static unsigned short handle_to_chunks(unsigned long handle)
491{
492 struct z3fold_buddy_slots *slots = handle_to_slots(handle);
493 unsigned long addr;
494
495 read_lock(&slots->lock);
496 addr = *(unsigned long *)handle;
497 read_unlock(&slots->lock);
498 return (addr & ~PAGE_MASK) >> BUDDY_SHIFT;
499}
500
501/*
502 * (handle & BUDDY_MASK) < zhdr->first_num is possible in encode_handle
503 * but that doesn't matter. because the masking will result in the
504 * correct buddy number.
505 */
506static enum buddy handle_to_buddy(unsigned long handle)
507{
508 struct z3fold_header *zhdr;
509 struct z3fold_buddy_slots *slots = handle_to_slots(handle);
510 unsigned long addr;
511
512 read_lock(&slots->lock);
513 WARN_ON(handle & (1 << PAGE_HEADLESS));
514 addr = *(unsigned long *)handle;
515 read_unlock(&slots->lock);
516 zhdr = (struct z3fold_header *)(addr & PAGE_MASK);
517 return (addr - zhdr->first_num) & BUDDY_MASK;
518}
519
520static inline struct z3fold_pool *zhdr_to_pool(struct z3fold_header *zhdr)
521{
522 return zhdr->pool;
523}
524
525static void __release_z3fold_page(struct z3fold_header *zhdr, bool locked)
526{
527 struct page *page = virt_to_page(zhdr);
528 struct z3fold_pool *pool = zhdr_to_pool(zhdr);
529 bool is_free = true;
530 int i;
531
532 WARN_ON(!list_empty(&zhdr->buddy));
533 set_bit(PAGE_STALE, &page->private);
534 clear_bit(NEEDS_COMPACTING, &page->private);
535 spin_lock(&pool->lock);
536 if (!list_empty(&page->lru))
537 list_del_init(&page->lru);
538 spin_unlock(&pool->lock);
539
540 /* If there are no foreign handles, free the handles array */
541 read_lock(&zhdr->slots->lock);
542 for (i = 0; i <= BUDDY_MASK; i++) {
543 if (zhdr->slots->slot[i]) {
544 is_free = false;
545 break;
546 }
547 }
548 if (!is_free)
549 set_bit(HANDLES_ORPHANED, &zhdr->slots->pool);
550 read_unlock(&zhdr->slots->lock);
551
552 if (is_free)
553 kmem_cache_free(pool->c_handle, zhdr->slots);
554
555 if (locked)
556 z3fold_page_unlock(zhdr);
557
558 spin_lock(&pool->stale_lock);
559 list_add(&zhdr->buddy, &pool->stale);
560 queue_work(pool->release_wq, &pool->work);
561 spin_unlock(&pool->stale_lock);
562}
563
564static void __attribute__((__unused__))
565 release_z3fold_page(struct kref *ref)
566{
567 struct z3fold_header *zhdr = container_of(ref, struct z3fold_header,
568 refcount);
569 __release_z3fold_page(zhdr, false);
570}
571
572static void release_z3fold_page_locked(struct kref *ref)
573{
574 struct z3fold_header *zhdr = container_of(ref, struct z3fold_header,
575 refcount);
576 WARN_ON(z3fold_page_trylock(zhdr));
577 __release_z3fold_page(zhdr, true);
578}
579
580static void release_z3fold_page_locked_list(struct kref *ref)
581{
582 struct z3fold_header *zhdr = container_of(ref, struct z3fold_header,
583 refcount);
584 struct z3fold_pool *pool = zhdr_to_pool(zhdr);
585
586 spin_lock(&pool->lock);
587 list_del_init(&zhdr->buddy);
588 spin_unlock(&pool->lock);
589
590 WARN_ON(z3fold_page_trylock(zhdr));
591 __release_z3fold_page(zhdr, true);
592}
593
594static void free_pages_work(struct work_struct *w)
595{
596 struct z3fold_pool *pool = container_of(w, struct z3fold_pool, work);
597
598 spin_lock(&pool->stale_lock);
599 while (!list_empty(&pool->stale)) {
600 struct z3fold_header *zhdr = list_first_entry(&pool->stale,
601 struct z3fold_header, buddy);
602 struct page *page = virt_to_page(zhdr);
603
604 list_del(&zhdr->buddy);
605 if (WARN_ON(!test_bit(PAGE_STALE, &page->private)))
606 continue;
607 spin_unlock(&pool->stale_lock);
608 cancel_work_sync(&zhdr->work);
609 free_z3fold_page(page, false);
610 cond_resched();
611 spin_lock(&pool->stale_lock);
612 }
613 spin_unlock(&pool->stale_lock);
614}
615
616/*
617 * Returns the number of free chunks in a z3fold page.
618 * NB: can't be used with HEADLESS pages.
619 */
620static int num_free_chunks(struct z3fold_header *zhdr)
621{
622 int nfree;
623 /*
624 * If there is a middle object, pick up the bigger free space
625 * either before or after it. Otherwise just subtract the number
626 * of chunks occupied by the first and the last objects.
627 */
628 if (zhdr->middle_chunks != 0) {
629 int nfree_before = zhdr->first_chunks ?
630 0 : zhdr->start_middle - ZHDR_CHUNKS;
631 int nfree_after = zhdr->last_chunks ?
632 0 : TOTAL_CHUNKS -
633 (zhdr->start_middle + zhdr->middle_chunks);
634 nfree = max(nfree_before, nfree_after);
635 } else
636 nfree = NCHUNKS - zhdr->first_chunks - zhdr->last_chunks;
637 return nfree;
638}
639
640/* Add to the appropriate unbuddied list */
641static inline void add_to_unbuddied(struct z3fold_pool *pool,
642 struct z3fold_header *zhdr)
643{
644 if (zhdr->first_chunks == 0 || zhdr->last_chunks == 0 ||
645 zhdr->middle_chunks == 0) {
646 struct list_head *unbuddied = get_cpu_ptr(pool->unbuddied);
647
648 int freechunks = num_free_chunks(zhdr);
649 spin_lock(&pool->lock);
650 list_add(&zhdr->buddy, &unbuddied[freechunks]);
651 spin_unlock(&pool->lock);
652 zhdr->cpu = smp_processor_id();
653 put_cpu_ptr(pool->unbuddied);
654 }
655}
656
657static inline void *mchunk_memmove(struct z3fold_header *zhdr,
658 unsigned short dst_chunk)
659{
660 void *beg = zhdr;
661 return memmove(beg + (dst_chunk << CHUNK_SHIFT),
662 beg + (zhdr->start_middle << CHUNK_SHIFT),
663 zhdr->middle_chunks << CHUNK_SHIFT);
664}
665
666static inline bool buddy_single(struct z3fold_header *zhdr)
667{
668 return !((zhdr->first_chunks && zhdr->middle_chunks) ||
669 (zhdr->first_chunks && zhdr->last_chunks) ||
670 (zhdr->middle_chunks && zhdr->last_chunks));
671}
672
673static struct z3fold_header *compact_single_buddy(struct z3fold_header *zhdr)
674{
675 struct z3fold_pool *pool = zhdr_to_pool(zhdr);
676 void *p = zhdr;
677 unsigned long old_handle = 0;
678 size_t sz = 0;
679 struct z3fold_header *new_zhdr = NULL;
680 int first_idx = __idx(zhdr, FIRST);
681 int middle_idx = __idx(zhdr, MIDDLE);
682 int last_idx = __idx(zhdr, LAST);
683 unsigned short *moved_chunks = NULL;
684
685 /*
686 * No need to protect slots here -- all the slots are "local" and
687 * the page lock is already taken
688 */
689 if (zhdr->first_chunks && zhdr->slots->slot[first_idx]) {
690 p += ZHDR_SIZE_ALIGNED;
691 sz = zhdr->first_chunks << CHUNK_SHIFT;
692 old_handle = (unsigned long)&zhdr->slots->slot[first_idx];
693 moved_chunks = &zhdr->first_chunks;
694 } else if (zhdr->middle_chunks && zhdr->slots->slot[middle_idx]) {
695 p += zhdr->start_middle << CHUNK_SHIFT;
696 sz = zhdr->middle_chunks << CHUNK_SHIFT;
697 old_handle = (unsigned long)&zhdr->slots->slot[middle_idx];
698 moved_chunks = &zhdr->middle_chunks;
699 } else if (zhdr->last_chunks && zhdr->slots->slot[last_idx]) {
700 p += PAGE_SIZE - (zhdr->last_chunks << CHUNK_SHIFT);
701 sz = zhdr->last_chunks << CHUNK_SHIFT;
702 old_handle = (unsigned long)&zhdr->slots->slot[last_idx];
703 moved_chunks = &zhdr->last_chunks;
704 }
705
706 if (sz > 0) {
707 enum buddy new_bud = HEADLESS;
708 short chunks = size_to_chunks(sz);
709 void *q;
710
711 new_zhdr = __z3fold_alloc(pool, sz, false);
712 if (!new_zhdr)
713 return NULL;
714
715 if (WARN_ON(new_zhdr == zhdr))
716 goto out_fail;
717
718 if (new_zhdr->first_chunks == 0) {
719 if (new_zhdr->middle_chunks != 0 &&
720 chunks >= new_zhdr->start_middle) {
721 new_bud = LAST;
722 } else {
723 new_bud = FIRST;
724 }
725 } else if (new_zhdr->last_chunks == 0) {
726 new_bud = LAST;
727 } else if (new_zhdr->middle_chunks == 0) {
728 new_bud = MIDDLE;
729 }
730 q = new_zhdr;
731 switch (new_bud) {
732 case FIRST:
733 new_zhdr->first_chunks = chunks;
734 q += ZHDR_SIZE_ALIGNED;
735 break;
736 case MIDDLE:
737 new_zhdr->middle_chunks = chunks;
738 new_zhdr->start_middle =
739 new_zhdr->first_chunks + ZHDR_CHUNKS;
740 q += new_zhdr->start_middle << CHUNK_SHIFT;
741 break;
742 case LAST:
743 new_zhdr->last_chunks = chunks;
744 q += PAGE_SIZE - (new_zhdr->last_chunks << CHUNK_SHIFT);
745 break;
746 default:
747 goto out_fail;
748 }
749 new_zhdr->foreign_handles++;
750 memcpy(q, p, sz);
751 write_lock(&zhdr->slots->lock);
752 *(unsigned long *)old_handle = (unsigned long)new_zhdr +
753 __idx(new_zhdr, new_bud);
754 if (new_bud == LAST)
755 *(unsigned long *)old_handle |=
756 (new_zhdr->last_chunks << BUDDY_SHIFT);
757 write_unlock(&zhdr->slots->lock);
758 add_to_unbuddied(pool, new_zhdr);
759 z3fold_page_unlock(new_zhdr);
760
761 *moved_chunks = 0;
762 }
763
764 return new_zhdr;
765
766out_fail:
767 if (new_zhdr) {
768 if (kref_put(&new_zhdr->refcount, release_z3fold_page_locked))
769 atomic64_dec(&pool->pages_nr);
770 else {
771 add_to_unbuddied(pool, new_zhdr);
772 z3fold_page_unlock(new_zhdr);
773 }
774 }
775 return NULL;
776
777}
778
779#define BIG_CHUNK_GAP 3
780/* Has to be called with lock held */
781static int z3fold_compact_page(struct z3fold_header *zhdr)
782{
783 struct page *page = virt_to_page(zhdr);
784
785 if (test_bit(MIDDLE_CHUNK_MAPPED, &page->private))
786 return 0; /* can't move middle chunk, it's used */
787
788 if (unlikely(PageIsolated(page)))
789 return 0;
790
791 if (zhdr->middle_chunks == 0)
792 return 0; /* nothing to compact */
793
794 if (zhdr->first_chunks == 0 && zhdr->last_chunks == 0) {
795 /* move to the beginning */
796 mchunk_memmove(zhdr, ZHDR_CHUNKS);
797 zhdr->first_chunks = zhdr->middle_chunks;
798 zhdr->middle_chunks = 0;
799 zhdr->start_middle = 0;
800 zhdr->first_num++;
801 return 1;
802 }
803
804 /*
805 * moving data is expensive, so let's only do that if
806 * there's substantial gain (at least BIG_CHUNK_GAP chunks)
807 */
808 if (zhdr->first_chunks != 0 && zhdr->last_chunks == 0 &&
809 zhdr->start_middle - (zhdr->first_chunks + ZHDR_CHUNKS) >=
810 BIG_CHUNK_GAP) {
811 mchunk_memmove(zhdr, zhdr->first_chunks + ZHDR_CHUNKS);
812 zhdr->start_middle = zhdr->first_chunks + ZHDR_CHUNKS;
813 return 1;
814 } else if (zhdr->last_chunks != 0 && zhdr->first_chunks == 0 &&
815 TOTAL_CHUNKS - (zhdr->last_chunks + zhdr->start_middle
816 + zhdr->middle_chunks) >=
817 BIG_CHUNK_GAP) {
818 unsigned short new_start = TOTAL_CHUNKS - zhdr->last_chunks -
819 zhdr->middle_chunks;
820 mchunk_memmove(zhdr, new_start);
821 zhdr->start_middle = new_start;
822 return 1;
823 }
824
825 return 0;
826}
827
828static void do_compact_page(struct z3fold_header *zhdr, bool locked)
829{
830 struct z3fold_pool *pool = zhdr_to_pool(zhdr);
831 struct page *page;
832
833 page = virt_to_page(zhdr);
834 if (locked)
835 WARN_ON(z3fold_page_trylock(zhdr));
836 else
837 z3fold_page_lock(zhdr);
838 if (WARN_ON(!test_and_clear_bit(NEEDS_COMPACTING, &page->private))) {
839 z3fold_page_unlock(zhdr);
840 return;
841 }
842 spin_lock(&pool->lock);
843 list_del_init(&zhdr->buddy);
844 spin_unlock(&pool->lock);
845
846 if (kref_put(&zhdr->refcount, release_z3fold_page_locked)) {
847 atomic64_dec(&pool->pages_nr);
848 return;
849 }
850
851 if (unlikely(PageIsolated(page) ||
852 test_bit(PAGE_CLAIMED, &page->private) ||
853 test_bit(PAGE_STALE, &page->private))) {
854 z3fold_page_unlock(zhdr);
855 return;
856 }
857
858 if (!zhdr->foreign_handles && buddy_single(zhdr) &&
859 zhdr->mapped_count == 0 && compact_single_buddy(zhdr)) {
860 if (kref_put(&zhdr->refcount, release_z3fold_page_locked))
861 atomic64_dec(&pool->pages_nr);
862 else
863 z3fold_page_unlock(zhdr);
864 return;
865 }
866
867 z3fold_compact_page(zhdr);
868 add_to_unbuddied(pool, zhdr);
869 z3fold_page_unlock(zhdr);
870}
871
872static void compact_page_work(struct work_struct *w)
873{
874 struct z3fold_header *zhdr = container_of(w, struct z3fold_header,
875 work);
876
877 do_compact_page(zhdr, false);
878}
879
880/* returns _locked_ z3fold page header or NULL */
881static inline struct z3fold_header *__z3fold_alloc(struct z3fold_pool *pool,
882 size_t size, bool can_sleep)
883{
884 struct z3fold_header *zhdr = NULL;
885 struct page *page;
886 struct list_head *unbuddied;
887 int chunks = size_to_chunks(size), i;
888
889lookup:
890 /* First, try to find an unbuddied z3fold page. */
891 unbuddied = get_cpu_ptr(pool->unbuddied);
892 for_each_unbuddied_list(i, chunks) {
893 struct list_head *l = &unbuddied[i];
894
895 zhdr = list_first_entry_or_null(READ_ONCE(l),
896 struct z3fold_header, buddy);
897
898 if (!zhdr)
899 continue;
900
901 /* Re-check under lock. */
902 spin_lock(&pool->lock);
903 l = &unbuddied[i];
904 if (unlikely(zhdr != list_first_entry(READ_ONCE(l),
905 struct z3fold_header, buddy)) ||
906 !z3fold_page_trylock(zhdr)) {
907 spin_unlock(&pool->lock);
908 zhdr = NULL;
909 put_cpu_ptr(pool->unbuddied);
910 if (can_sleep)
911 cond_resched();
912 goto lookup;
913 }
914 list_del_init(&zhdr->buddy);
915 zhdr->cpu = -1;
916 spin_unlock(&pool->lock);
917
918 page = virt_to_page(zhdr);
919 if (test_bit(NEEDS_COMPACTING, &page->private) ||
920 test_bit(PAGE_CLAIMED, &page->private)) {
921 z3fold_page_unlock(zhdr);
922 zhdr = NULL;
923 put_cpu_ptr(pool->unbuddied);
924 if (can_sleep)
925 cond_resched();
926 goto lookup;
927 }
928
929 /*
930 * this page could not be removed from its unbuddied
931 * list while pool lock was held, and then we've taken
932 * page lock so kref_put could not be called before
933 * we got here, so it's safe to just call kref_get()
934 */
935 kref_get(&zhdr->refcount);
936 break;
937 }
938 put_cpu_ptr(pool->unbuddied);
939
940 if (!zhdr) {
941 int cpu;
942
943 /* look for _exact_ match on other cpus' lists */
944 for_each_online_cpu(cpu) {
945 struct list_head *l;
946
947 unbuddied = per_cpu_ptr(pool->unbuddied, cpu);
948 spin_lock(&pool->lock);
949 l = &unbuddied[chunks];
950
951 zhdr = list_first_entry_or_null(READ_ONCE(l),
952 struct z3fold_header, buddy);
953
954 if (!zhdr || !z3fold_page_trylock(zhdr)) {
955 spin_unlock(&pool->lock);
956 zhdr = NULL;
957 continue;
958 }
959 list_del_init(&zhdr->buddy);
960 zhdr->cpu = -1;
961 spin_unlock(&pool->lock);
962
963 page = virt_to_page(zhdr);
964 if (test_bit(NEEDS_COMPACTING, &page->private) ||
965 test_bit(PAGE_CLAIMED, &page->private)) {
966 z3fold_page_unlock(zhdr);
967 zhdr = NULL;
968 if (can_sleep)
969 cond_resched();
970 continue;
971 }
972 kref_get(&zhdr->refcount);
973 break;
974 }
975 }
976
977 return zhdr;
978}
979
980/*
981 * API Functions
982 */
983
984/**
985 * z3fold_create_pool() - create a new z3fold pool
986 * @name: pool name
987 * @gfp: gfp flags when allocating the z3fold pool structure
988 * @ops: user-defined operations for the z3fold pool
989 *
990 * Return: pointer to the new z3fold pool or NULL if the metadata allocation
991 * failed.
992 */
993static struct z3fold_pool *z3fold_create_pool(const char *name, gfp_t gfp,
994 const struct z3fold_ops *ops)
995{
996 struct z3fold_pool *pool = NULL;
997 int i, cpu;
998
999 pool = kzalloc(sizeof(struct z3fold_pool), gfp);
1000 if (!pool)
1001 goto out;
1002 pool->c_handle = kmem_cache_create("z3fold_handle",
1003 sizeof(struct z3fold_buddy_slots),
1004 SLOTS_ALIGN, 0, NULL);
1005 if (!pool->c_handle)
1006 goto out_c;
1007 spin_lock_init(&pool->lock);
1008 spin_lock_init(&pool->stale_lock);
1009 pool->unbuddied = __alloc_percpu(sizeof(struct list_head)*NCHUNKS, 2);
1010 if (!pool->unbuddied)
1011 goto out_pool;
1012 for_each_possible_cpu(cpu) {
1013 struct list_head *unbuddied =
1014 per_cpu_ptr(pool->unbuddied, cpu);
1015 for_each_unbuddied_list(i, 0)
1016 INIT_LIST_HEAD(&unbuddied[i]);
1017 }
1018 INIT_LIST_HEAD(&pool->lru);
1019 INIT_LIST_HEAD(&pool->stale);
1020 atomic64_set(&pool->pages_nr, 0);
1021 pool->name = name;
1022 pool->compact_wq = create_singlethread_workqueue(pool->name);
1023 if (!pool->compact_wq)
1024 goto out_unbuddied;
1025 pool->release_wq = create_singlethread_workqueue(pool->name);
1026 if (!pool->release_wq)
1027 goto out_wq;
1028 if (z3fold_register_migration(pool))
1029 goto out_rwq;
1030 INIT_WORK(&pool->work, free_pages_work);
1031 pool->ops = ops;
1032 return pool;
1033
1034out_rwq:
1035 destroy_workqueue(pool->release_wq);
1036out_wq:
1037 destroy_workqueue(pool->compact_wq);
1038out_unbuddied:
1039 free_percpu(pool->unbuddied);
1040out_pool:
1041 kmem_cache_destroy(pool->c_handle);
1042out_c:
1043 kfree(pool);
1044out:
1045 return NULL;
1046}
1047
1048/**
1049 * z3fold_destroy_pool() - destroys an existing z3fold pool
1050 * @pool: the z3fold pool to be destroyed
1051 *
1052 * The pool should be emptied before this function is called.
1053 */
1054static void z3fold_destroy_pool(struct z3fold_pool *pool)
1055{
1056 kmem_cache_destroy(pool->c_handle);
1057
1058 /*
1059 * We need to destroy pool->compact_wq before pool->release_wq,
1060 * as any pending work on pool->compact_wq will call
1061 * queue_work(pool->release_wq, &pool->work).
1062 *
1063 * There are still outstanding pages until both workqueues are drained,
1064 * so we cannot unregister migration until then.
1065 */
1066
1067 destroy_workqueue(pool->compact_wq);
1068 destroy_workqueue(pool->release_wq);
1069 z3fold_unregister_migration(pool);
1070 kfree(pool);
1071}
1072
1073/**
1074 * z3fold_alloc() - allocates a region of a given size
1075 * @pool: z3fold pool from which to allocate
1076 * @size: size in bytes of the desired allocation
1077 * @gfp: gfp flags used if the pool needs to grow
1078 * @handle: handle of the new allocation
1079 *
1080 * This function will attempt to find a free region in the pool large enough to
1081 * satisfy the allocation request. A search of the unbuddied lists is
1082 * performed first. If no suitable free region is found, then a new page is
1083 * allocated and added to the pool to satisfy the request.
1084 *
1085 * gfp should not set __GFP_HIGHMEM as highmem pages cannot be used
1086 * as z3fold pool pages.
1087 *
1088 * Return: 0 if success and handle is set, otherwise -EINVAL if the size or
1089 * gfp arguments are invalid or -ENOMEM if the pool was unable to allocate
1090 * a new page.
1091 */
1092static int z3fold_alloc(struct z3fold_pool *pool, size_t size, gfp_t gfp,
1093 unsigned long *handle)
1094{
1095 int chunks = size_to_chunks(size);
1096 struct z3fold_header *zhdr = NULL;
1097 struct page *page = NULL;
1098 enum buddy bud;
1099 bool can_sleep = gfpflags_allow_blocking(gfp);
1100
1101 if (!size)
1102 return -EINVAL;
1103
1104 if (size > PAGE_SIZE)
1105 return -ENOSPC;
1106
1107 if (size > PAGE_SIZE - ZHDR_SIZE_ALIGNED - CHUNK_SIZE)
1108 bud = HEADLESS;
1109 else {
1110retry:
1111 zhdr = __z3fold_alloc(pool, size, can_sleep);
1112 if (zhdr) {
1113 if (zhdr->first_chunks == 0) {
1114 if (zhdr->middle_chunks != 0 &&
1115 chunks >= zhdr->start_middle)
1116 bud = LAST;
1117 else
1118 bud = FIRST;
1119 } else if (zhdr->last_chunks == 0)
1120 bud = LAST;
1121 else if (zhdr->middle_chunks == 0)
1122 bud = MIDDLE;
1123 else {
1124 if (kref_put(&zhdr->refcount,
1125 release_z3fold_page_locked))
1126 atomic64_dec(&pool->pages_nr);
1127 else
1128 z3fold_page_unlock(zhdr);
1129 pr_err("No free chunks in unbuddied\n");
1130 WARN_ON(1);
1131 goto retry;
1132 }
1133 page = virt_to_page(zhdr);
1134 goto found;
1135 }
1136 bud = FIRST;
1137 }
1138
1139 page = NULL;
1140 if (can_sleep) {
1141 spin_lock(&pool->stale_lock);
1142 zhdr = list_first_entry_or_null(&pool->stale,
1143 struct z3fold_header, buddy);
1144 /*
1145 * Before allocating a page, let's see if we can take one from
1146 * the stale pages list. cancel_work_sync() can sleep so we
1147 * limit this case to the contexts where we can sleep
1148 */
1149 if (zhdr) {
1150 list_del(&zhdr->buddy);
1151 spin_unlock(&pool->stale_lock);
1152 cancel_work_sync(&zhdr->work);
1153 page = virt_to_page(zhdr);
1154 } else {
1155 spin_unlock(&pool->stale_lock);
1156 }
1157 }
1158 if (!page)
1159 page = alloc_page(gfp);
1160
1161 if (!page)
1162 return -ENOMEM;
1163
1164 zhdr = init_z3fold_page(page, bud == HEADLESS, pool, gfp);
1165 if (!zhdr) {
1166 __free_page(page);
1167 return -ENOMEM;
1168 }
1169 atomic64_inc(&pool->pages_nr);
1170
1171 if (bud == HEADLESS) {
1172 set_bit(PAGE_HEADLESS, &page->private);
1173 goto headless;
1174 }
1175 if (can_sleep) {
1176 lock_page(page);
1177 __SetPageMovable(page, pool->inode->i_mapping);
1178 unlock_page(page);
1179 } else {
1180 if (trylock_page(page)) {
1181 __SetPageMovable(page, pool->inode->i_mapping);
1182 unlock_page(page);
1183 }
1184 }
1185 z3fold_page_lock(zhdr);
1186
1187found:
1188 if (bud == FIRST)
1189 zhdr->first_chunks = chunks;
1190 else if (bud == LAST)
1191 zhdr->last_chunks = chunks;
1192 else {
1193 zhdr->middle_chunks = chunks;
1194 zhdr->start_middle = zhdr->first_chunks + ZHDR_CHUNKS;
1195 }
1196 add_to_unbuddied(pool, zhdr);
1197
1198headless:
1199 spin_lock(&pool->lock);
1200 /* Add/move z3fold page to beginning of LRU */
1201 if (!list_empty(&page->lru))
1202 list_del(&page->lru);
1203
1204 list_add(&page->lru, &pool->lru);
1205
1206 *handle = encode_handle(zhdr, bud);
1207 spin_unlock(&pool->lock);
1208 if (bud != HEADLESS)
1209 z3fold_page_unlock(zhdr);
1210
1211 return 0;
1212}
1213
1214/**
1215 * z3fold_free() - frees the allocation associated with the given handle
1216 * @pool: pool in which the allocation resided
1217 * @handle: handle associated with the allocation returned by z3fold_alloc()
1218 *
1219 * In the case that the z3fold page in which the allocation resides is under
1220 * reclaim, as indicated by the PG_reclaim flag being set, this function
1221 * only sets the first|last_chunks to 0. The page is actually freed
1222 * once both buddies are evicted (see z3fold_reclaim_page() below).
1223 */
1224static void z3fold_free(struct z3fold_pool *pool, unsigned long handle)
1225{
1226 struct z3fold_header *zhdr;
1227 struct page *page;
1228 enum buddy bud;
1229 bool page_claimed;
1230
1231 zhdr = get_z3fold_header(handle);
1232 page = virt_to_page(zhdr);
1233 page_claimed = test_and_set_bit(PAGE_CLAIMED, &page->private);
1234
1235 if (test_bit(PAGE_HEADLESS, &page->private)) {
1236 /* if a headless page is under reclaim, just leave.
1237 * NB: we use test_and_set_bit for a reason: if the bit
1238 * has not been set before, we release this page
1239 * immediately so we don't care about its value any more.
1240 */
1241 if (!page_claimed) {
1242 spin_lock(&pool->lock);
1243 list_del(&page->lru);
1244 spin_unlock(&pool->lock);
1245 put_z3fold_header(zhdr);
1246 free_z3fold_page(page, true);
1247 atomic64_dec(&pool->pages_nr);
1248 }
1249 return;
1250 }
1251
1252 /* Non-headless case */
1253 bud = handle_to_buddy(handle);
1254
1255 switch (bud) {
1256 case FIRST:
1257 zhdr->first_chunks = 0;
1258 break;
1259 case MIDDLE:
1260 zhdr->middle_chunks = 0;
1261 break;
1262 case LAST:
1263 zhdr->last_chunks = 0;
1264 break;
1265 default:
1266 pr_err("%s: unknown bud %d\n", __func__, bud);
1267 WARN_ON(1);
1268 put_z3fold_header(zhdr);
1269 clear_bit(PAGE_CLAIMED, &page->private);
1270 return;
1271 }
1272
1273 if (!page_claimed)
1274 free_handle(handle);
1275 if (kref_put(&zhdr->refcount, release_z3fold_page_locked_list)) {
1276 atomic64_dec(&pool->pages_nr);
1277 return;
1278 }
1279 if (page_claimed) {
1280 /* the page has not been claimed by us */
1281 z3fold_page_unlock(zhdr);
1282 return;
1283 }
1284 if (unlikely(PageIsolated(page)) ||
1285 test_and_set_bit(NEEDS_COMPACTING, &page->private)) {
1286 put_z3fold_header(zhdr);
1287 clear_bit(PAGE_CLAIMED, &page->private);
1288 return;
1289 }
1290 if (zhdr->cpu < 0 || !cpu_online(zhdr->cpu)) {
1291 spin_lock(&pool->lock);
1292 list_del_init(&zhdr->buddy);
1293 spin_unlock(&pool->lock);
1294 zhdr->cpu = -1;
1295 kref_get(&zhdr->refcount);
1296 clear_bit(PAGE_CLAIMED, &page->private);
1297 do_compact_page(zhdr, true);
1298 return;
1299 }
1300 kref_get(&zhdr->refcount);
1301 clear_bit(PAGE_CLAIMED, &page->private);
1302 queue_work_on(zhdr->cpu, pool->compact_wq, &zhdr->work);
1303 put_z3fold_header(zhdr);
1304}
1305
1306/**
1307 * z3fold_reclaim_page() - evicts allocations from a pool page and frees it
1308 * @pool: pool from which a page will attempt to be evicted
1309 * @retries: number of pages on the LRU list for which eviction will
1310 * be attempted before failing
1311 *
1312 * z3fold reclaim is different from normal system reclaim in that it is done
1313 * from the bottom, up. This is because only the bottom layer, z3fold, has
1314 * information on how the allocations are organized within each z3fold page.
1315 * This has the potential to create interesting locking situations between
1316 * z3fold and the user, however.
1317 *
1318 * To avoid these, this is how z3fold_reclaim_page() should be called:
1319 *
1320 * The user detects a page should be reclaimed and calls z3fold_reclaim_page().
1321 * z3fold_reclaim_page() will remove a z3fold page from the pool LRU list and
1322 * call the user-defined eviction handler with the pool and handle as
1323 * arguments.
1324 *
1325 * If the handle can not be evicted, the eviction handler should return
1326 * non-zero. z3fold_reclaim_page() will add the z3fold page back to the
1327 * appropriate list and try the next z3fold page on the LRU up to
1328 * a user defined number of retries.
1329 *
1330 * If the handle is successfully evicted, the eviction handler should
1331 * return 0 _and_ should have called z3fold_free() on the handle. z3fold_free()
1332 * contains logic to delay freeing the page if the page is under reclaim,
1333 * as indicated by the setting of the PG_reclaim flag on the underlying page.
1334 *
1335 * If all buddies in the z3fold page are successfully evicted, then the
1336 * z3fold page can be freed.
1337 *
1338 * Returns: 0 if page is successfully freed, otherwise -EINVAL if there are
1339 * no pages to evict or an eviction handler is not registered, -EAGAIN if
1340 * the retry limit was hit.
1341 */
1342static int z3fold_reclaim_page(struct z3fold_pool *pool, unsigned int retries)
1343{
1344 int i, ret = -1;
1345 struct z3fold_header *zhdr = NULL;
1346 struct page *page = NULL;
1347 struct list_head *pos;
1348 unsigned long first_handle = 0, middle_handle = 0, last_handle = 0;
1349
1350 spin_lock(&pool->lock);
1351 if (!pool->ops || !pool->ops->evict || retries == 0) {
1352 spin_unlock(&pool->lock);
1353 return -EINVAL;
1354 }
1355 for (i = 0; i < retries; i++) {
1356 if (list_empty(&pool->lru)) {
1357 spin_unlock(&pool->lock);
1358 return -EINVAL;
1359 }
1360 list_for_each_prev(pos, &pool->lru) {
1361 page = list_entry(pos, struct page, lru);
1362
1363 /* this bit could have been set by free, in which case
1364 * we pass over to the next page in the pool.
1365 */
1366 if (test_and_set_bit(PAGE_CLAIMED, &page->private)) {
1367 page = NULL;
1368 continue;
1369 }
1370
1371 if (unlikely(PageIsolated(page))) {
1372 clear_bit(PAGE_CLAIMED, &page->private);
1373 page = NULL;
1374 continue;
1375 }
1376 zhdr = page_address(page);
1377 if (test_bit(PAGE_HEADLESS, &page->private))
1378 break;
1379
1380 if (!z3fold_page_trylock(zhdr)) {
1381 clear_bit(PAGE_CLAIMED, &page->private);
1382 zhdr = NULL;
1383 continue; /* can't evict at this point */
1384 }
1385 if (zhdr->foreign_handles) {
1386 clear_bit(PAGE_CLAIMED, &page->private);
1387 z3fold_page_unlock(zhdr);
1388 zhdr = NULL;
1389 continue; /* can't evict such page */
1390 }
1391 kref_get(&zhdr->refcount);
1392 list_del_init(&zhdr->buddy);
1393 zhdr->cpu = -1;
1394 break;
1395 }
1396
1397 if (!zhdr)
1398 break;
1399
1400 list_del_init(&page->lru);
1401 spin_unlock(&pool->lock);
1402
1403 if (!test_bit(PAGE_HEADLESS, &page->private)) {
1404 /*
1405 * We need encode the handles before unlocking, and
1406 * use our local slots structure because z3fold_free
1407 * can zero out zhdr->slots and we can't do much
1408 * about that
1409 */
1410 first_handle = 0;
1411 last_handle = 0;
1412 middle_handle = 0;
1413 if (zhdr->first_chunks)
1414 first_handle = encode_handle(zhdr, FIRST);
1415 if (zhdr->middle_chunks)
1416 middle_handle = encode_handle(zhdr, MIDDLE);
1417 if (zhdr->last_chunks)
1418 last_handle = encode_handle(zhdr, LAST);
1419 /*
1420 * it's safe to unlock here because we hold a
1421 * reference to this page
1422 */
1423 z3fold_page_unlock(zhdr);
1424 } else {
1425 first_handle = encode_handle(zhdr, HEADLESS);
1426 last_handle = middle_handle = 0;
1427 }
1428 /* Issue the eviction callback(s) */
1429 if (middle_handle) {
1430 ret = pool->ops->evict(pool, middle_handle);
1431 if (ret)
1432 goto next;
1433 free_handle(middle_handle);
1434 }
1435 if (first_handle) {
1436 ret = pool->ops->evict(pool, first_handle);
1437 if (ret)
1438 goto next;
1439 free_handle(first_handle);
1440 }
1441 if (last_handle) {
1442 ret = pool->ops->evict(pool, last_handle);
1443 if (ret)
1444 goto next;
1445 free_handle(last_handle);
1446 }
1447next:
1448 if (test_bit(PAGE_HEADLESS, &page->private)) {
1449 if (ret == 0) {
1450 free_z3fold_page(page, true);
1451 atomic64_dec(&pool->pages_nr);
1452 return 0;
1453 }
1454 spin_lock(&pool->lock);
1455 list_add(&page->lru, &pool->lru);
1456 spin_unlock(&pool->lock);
1457 clear_bit(PAGE_CLAIMED, &page->private);
1458 } else {
1459 z3fold_page_lock(zhdr);
1460 if (kref_put(&zhdr->refcount,
1461 release_z3fold_page_locked)) {
1462 atomic64_dec(&pool->pages_nr);
1463 return 0;
1464 }
1465 /*
1466 * if we are here, the page is still not completely
1467 * free. Take the global pool lock then to be able
1468 * to add it back to the lru list
1469 */
1470 spin_lock(&pool->lock);
1471 list_add(&page->lru, &pool->lru);
1472 spin_unlock(&pool->lock);
1473 z3fold_page_unlock(zhdr);
1474 clear_bit(PAGE_CLAIMED, &page->private);
1475 }
1476
1477 /* We started off locked to we need to lock the pool back */
1478 spin_lock(&pool->lock);
1479 }
1480 spin_unlock(&pool->lock);
1481 return -EAGAIN;
1482}
1483
1484/**
1485 * z3fold_map() - maps the allocation associated with the given handle
1486 * @pool: pool in which the allocation resides
1487 * @handle: handle associated with the allocation to be mapped
1488 *
1489 * Extracts the buddy number from handle and constructs the pointer to the
1490 * correct starting chunk within the page.
1491 *
1492 * Returns: a pointer to the mapped allocation
1493 */
1494static void *z3fold_map(struct z3fold_pool *pool, unsigned long handle)
1495{
1496 struct z3fold_header *zhdr;
1497 struct page *page;
1498 void *addr;
1499 enum buddy buddy;
1500
1501 zhdr = get_z3fold_header(handle);
1502 addr = zhdr;
1503 page = virt_to_page(zhdr);
1504
1505 if (test_bit(PAGE_HEADLESS, &page->private))
1506 goto out;
1507
1508 buddy = handle_to_buddy(handle);
1509 switch (buddy) {
1510 case FIRST:
1511 addr += ZHDR_SIZE_ALIGNED;
1512 break;
1513 case MIDDLE:
1514 addr += zhdr->start_middle << CHUNK_SHIFT;
1515 set_bit(MIDDLE_CHUNK_MAPPED, &page->private);
1516 break;
1517 case LAST:
1518 addr += PAGE_SIZE - (handle_to_chunks(handle) << CHUNK_SHIFT);
1519 break;
1520 default:
1521 pr_err("unknown buddy id %d\n", buddy);
1522 WARN_ON(1);
1523 addr = NULL;
1524 break;
1525 }
1526
1527 if (addr)
1528 zhdr->mapped_count++;
1529out:
1530 put_z3fold_header(zhdr);
1531 return addr;
1532}
1533
1534/**
1535 * z3fold_unmap() - unmaps the allocation associated with the given handle
1536 * @pool: pool in which the allocation resides
1537 * @handle: handle associated with the allocation to be unmapped
1538 */
1539static void z3fold_unmap(struct z3fold_pool *pool, unsigned long handle)
1540{
1541 struct z3fold_header *zhdr;
1542 struct page *page;
1543 enum buddy buddy;
1544
1545 zhdr = get_z3fold_header(handle);
1546 page = virt_to_page(zhdr);
1547
1548 if (test_bit(PAGE_HEADLESS, &page->private))
1549 return;
1550
1551 buddy = handle_to_buddy(handle);
1552 if (buddy == MIDDLE)
1553 clear_bit(MIDDLE_CHUNK_MAPPED, &page->private);
1554 zhdr->mapped_count--;
1555 put_z3fold_header(zhdr);
1556}
1557
1558/**
1559 * z3fold_get_pool_size() - gets the z3fold pool size in pages
1560 * @pool: pool whose size is being queried
1561 *
1562 * Returns: size in pages of the given pool.
1563 */
1564static u64 z3fold_get_pool_size(struct z3fold_pool *pool)
1565{
1566 return atomic64_read(&pool->pages_nr);
1567}
1568
1569static bool z3fold_page_isolate(struct page *page, isolate_mode_t mode)
1570{
1571 struct z3fold_header *zhdr;
1572 struct z3fold_pool *pool;
1573
1574 VM_BUG_ON_PAGE(!PageMovable(page), page);
1575 VM_BUG_ON_PAGE(PageIsolated(page), page);
1576
1577 if (test_bit(PAGE_HEADLESS, &page->private) ||
1578 test_bit(PAGE_CLAIMED, &page->private))
1579 return false;
1580
1581 zhdr = page_address(page);
1582 z3fold_page_lock(zhdr);
1583 if (test_bit(NEEDS_COMPACTING, &page->private) ||
1584 test_bit(PAGE_STALE, &page->private))
1585 goto out;
1586
1587 if (zhdr->mapped_count != 0 || zhdr->foreign_handles != 0)
1588 goto out;
1589
1590 pool = zhdr_to_pool(zhdr);
1591 spin_lock(&pool->lock);
1592 if (!list_empty(&zhdr->buddy))
1593 list_del_init(&zhdr->buddy);
1594 if (!list_empty(&page->lru))
1595 list_del_init(&page->lru);
1596 spin_unlock(&pool->lock);
1597
1598 kref_get(&zhdr->refcount);
1599 z3fold_page_unlock(zhdr);
1600 return true;
1601
1602out:
1603 z3fold_page_unlock(zhdr);
1604 return false;
1605}
1606
1607static int z3fold_page_migrate(struct address_space *mapping, struct page *newpage,
1608 struct page *page, enum migrate_mode mode)
1609{
1610 struct z3fold_header *zhdr, *new_zhdr;
1611 struct z3fold_pool *pool;
1612 struct address_space *new_mapping;
1613
1614 VM_BUG_ON_PAGE(!PageMovable(page), page);
1615 VM_BUG_ON_PAGE(!PageIsolated(page), page);
1616 VM_BUG_ON_PAGE(!PageLocked(newpage), newpage);
1617
1618 zhdr = page_address(page);
1619 pool = zhdr_to_pool(zhdr);
1620
1621 if (!z3fold_page_trylock(zhdr)) {
1622 return -EAGAIN;
1623 }
1624 if (zhdr->mapped_count != 0 || zhdr->foreign_handles != 0) {
1625 z3fold_page_unlock(zhdr);
1626 return -EBUSY;
1627 }
1628 if (work_pending(&zhdr->work)) {
1629 z3fold_page_unlock(zhdr);
1630 return -EAGAIN;
1631 }
1632 new_zhdr = page_address(newpage);
1633 memcpy(new_zhdr, zhdr, PAGE_SIZE);
1634 newpage->private = page->private;
1635 page->private = 0;
1636 z3fold_page_unlock(zhdr);
1637 spin_lock_init(&new_zhdr->page_lock);
1638 INIT_WORK(&new_zhdr->work, compact_page_work);
1639 /*
1640 * z3fold_page_isolate() ensures that new_zhdr->buddy is empty,
1641 * so we only have to reinitialize it.
1642 */
1643 INIT_LIST_HEAD(&new_zhdr->buddy);
1644 new_mapping = page_mapping(page);
1645 __ClearPageMovable(page);
1646 ClearPagePrivate(page);
1647
1648 get_page(newpage);
1649 z3fold_page_lock(new_zhdr);
1650 if (new_zhdr->first_chunks)
1651 encode_handle(new_zhdr, FIRST);
1652 if (new_zhdr->last_chunks)
1653 encode_handle(new_zhdr, LAST);
1654 if (new_zhdr->middle_chunks)
1655 encode_handle(new_zhdr, MIDDLE);
1656 set_bit(NEEDS_COMPACTING, &newpage->private);
1657 new_zhdr->cpu = smp_processor_id();
1658 spin_lock(&pool->lock);
1659 list_add(&newpage->lru, &pool->lru);
1660 spin_unlock(&pool->lock);
1661 __SetPageMovable(newpage, new_mapping);
1662 z3fold_page_unlock(new_zhdr);
1663
1664 queue_work_on(new_zhdr->cpu, pool->compact_wq, &new_zhdr->work);
1665
1666 page_mapcount_reset(page);
1667 put_page(page);
1668 return 0;
1669}
1670
1671static void z3fold_page_putback(struct page *page)
1672{
1673 struct z3fold_header *zhdr;
1674 struct z3fold_pool *pool;
1675
1676 zhdr = page_address(page);
1677 pool = zhdr_to_pool(zhdr);
1678
1679 z3fold_page_lock(zhdr);
1680 if (!list_empty(&zhdr->buddy))
1681 list_del_init(&zhdr->buddy);
1682 INIT_LIST_HEAD(&page->lru);
1683 if (kref_put(&zhdr->refcount, release_z3fold_page_locked)) {
1684 atomic64_dec(&pool->pages_nr);
1685 return;
1686 }
1687 spin_lock(&pool->lock);
1688 list_add(&page->lru, &pool->lru);
1689 spin_unlock(&pool->lock);
1690 z3fold_page_unlock(zhdr);
1691}
1692
1693static const struct address_space_operations z3fold_aops = {
1694 .isolate_page = z3fold_page_isolate,
1695 .migratepage = z3fold_page_migrate,
1696 .putback_page = z3fold_page_putback,
1697};
1698
1699/*****************
1700 * zpool
1701 ****************/
1702
1703static int z3fold_zpool_evict(struct z3fold_pool *pool, unsigned long handle)
1704{
1705 if (pool->zpool && pool->zpool_ops && pool->zpool_ops->evict)
1706 return pool->zpool_ops->evict(pool->zpool, handle);
1707 else
1708 return -ENOENT;
1709}
1710
1711static const struct z3fold_ops z3fold_zpool_ops = {
1712 .evict = z3fold_zpool_evict
1713};
1714
1715static void *z3fold_zpool_create(const char *name, gfp_t gfp,
1716 const struct zpool_ops *zpool_ops,
1717 struct zpool *zpool)
1718{
1719 struct z3fold_pool *pool;
1720
1721 pool = z3fold_create_pool(name, gfp,
1722 zpool_ops ? &z3fold_zpool_ops : NULL);
1723 if (pool) {
1724 pool->zpool = zpool;
1725 pool->zpool_ops = zpool_ops;
1726 }
1727 return pool;
1728}
1729
1730static void z3fold_zpool_destroy(void *pool)
1731{
1732 z3fold_destroy_pool(pool);
1733}
1734
1735static int z3fold_zpool_malloc(void *pool, size_t size, gfp_t gfp,
1736 unsigned long *handle)
1737{
1738 return z3fold_alloc(pool, size, gfp, handle);
1739}
1740static void z3fold_zpool_free(void *pool, unsigned long handle)
1741{
1742 z3fold_free(pool, handle);
1743}
1744
1745static int z3fold_zpool_shrink(void *pool, unsigned int pages,
1746 unsigned int *reclaimed)
1747{
1748 unsigned int total = 0;
1749 int ret = -EINVAL;
1750
1751 while (total < pages) {
1752 ret = z3fold_reclaim_page(pool, 8);
1753 if (ret < 0)
1754 break;
1755 total++;
1756 }
1757
1758 if (reclaimed)
1759 *reclaimed = total;
1760
1761 return ret;
1762}
1763
1764static void *z3fold_zpool_map(void *pool, unsigned long handle,
1765 enum zpool_mapmode mm)
1766{
1767 return z3fold_map(pool, handle);
1768}
1769static void z3fold_zpool_unmap(void *pool, unsigned long handle)
1770{
1771 z3fold_unmap(pool, handle);
1772}
1773
1774static u64 z3fold_zpool_total_size(void *pool)
1775{
1776 return z3fold_get_pool_size(pool) * PAGE_SIZE;
1777}
1778
1779static struct zpool_driver z3fold_zpool_driver = {
1780 .type = "z3fold",
1781 .owner = THIS_MODULE,
1782 .create = z3fold_zpool_create,
1783 .destroy = z3fold_zpool_destroy,
1784 .malloc = z3fold_zpool_malloc,
1785 .free = z3fold_zpool_free,
1786 .shrink = z3fold_zpool_shrink,
1787 .map = z3fold_zpool_map,
1788 .unmap = z3fold_zpool_unmap,
1789 .total_size = z3fold_zpool_total_size,
1790};
1791
1792MODULE_ALIAS("zpool-z3fold");
1793
1794static int __init init_z3fold(void)
1795{
1796 int ret;
1797
1798 /* Make sure the z3fold header is not larger than the page size */
1799 BUILD_BUG_ON(ZHDR_SIZE_ALIGNED > PAGE_SIZE);
1800 ret = z3fold_mount();
1801 if (ret)
1802 return ret;
1803
1804 zpool_register_driver(&z3fold_zpool_driver);
1805
1806 return 0;
1807}
1808
1809static void __exit exit_z3fold(void)
1810{
1811 z3fold_unmount();
1812 zpool_unregister_driver(&z3fold_zpool_driver);
1813}
1814
1815module_init(init_z3fold);
1816module_exit(exit_z3fold);
1817
1818MODULE_LICENSE("GPL");
1819MODULE_AUTHOR("Vitaly Wool <vitalywool@gmail.com>");
1820MODULE_DESCRIPTION("3-Fold Allocator for Compressed Pages");