Merge tag 'iommu-updates-v6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/joro...
[platform/kernel/linux-starfive.git] / mm / z3fold.c
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 *****************/
70 struct z3fold_pool;
71
72 enum buddy {
73         HEADLESS = 0,
74         FIRST,
75         MIDDLE,
76         LAST,
77         BUDDIES_MAX = LAST
78 };
79
80 struct 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  */
108 struct 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 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  * @stale:      list of pages marked for freeing
134  * @pages_nr:   number of z3fold pages in the pool.
135  * @c_handle:   cache for z3fold_buddy_slots allocation
136  * @compact_wq: workqueue for page layout background optimization
137  * @release_wq: workqueue for safe page release
138  * @work:       work_struct for safe page release
139  *
140  * This structure is allocated at pool creation time and maintains metadata
141  * pertaining to a particular z3fold pool.
142  */
143 struct z3fold_pool {
144         const char *name;
145         spinlock_t lock;
146         spinlock_t stale_lock;
147         struct list_head *unbuddied;
148         struct list_head stale;
149         atomic64_t pages_nr;
150         struct kmem_cache *c_handle;
151         struct workqueue_struct *compact_wq;
152         struct workqueue_struct *release_wq;
153         struct work_struct work;
154 };
155
156 /*
157  * Internal z3fold page flags
158  */
159 enum z3fold_page_flags {
160         PAGE_HEADLESS = 0,
161         MIDDLE_CHUNK_MAPPED,
162         NEEDS_COMPACTING,
163         PAGE_STALE,
164         PAGE_CLAIMED, /* by either reclaim or free */
165         PAGE_MIGRATED, /* page is migrated and soon to be released */
166 };
167
168 /*
169  * handle flags, go under HANDLE_FLAG_MASK
170  */
171 enum z3fold_handle_flags {
172         HANDLES_NOFREE = 0,
173 };
174
175 /*
176  * Forward declarations
177  */
178 static struct z3fold_header *__z3fold_alloc(struct z3fold_pool *, size_t, bool);
179 static void compact_page_work(struct work_struct *w);
180
181 /*****************
182  * Helpers
183 *****************/
184
185 /* Converts an allocation size in bytes to size in z3fold chunks */
186 static int size_to_chunks(size_t size)
187 {
188         return (size + CHUNK_SIZE - 1) >> CHUNK_SHIFT;
189 }
190
191 #define for_each_unbuddied_list(_iter, _begin) \
192         for ((_iter) = (_begin); (_iter) < NCHUNKS; (_iter)++)
193
194 static inline struct z3fold_buddy_slots *alloc_slots(struct z3fold_pool *pool,
195                                                         gfp_t gfp)
196 {
197         struct z3fold_buddy_slots *slots = kmem_cache_zalloc(pool->c_handle,
198                                                              gfp);
199
200         if (slots) {
201                 /* It will be freed separately in free_handle(). */
202                 kmemleak_not_leak(slots);
203                 slots->pool = (unsigned long)pool;
204                 rwlock_init(&slots->lock);
205         }
206
207         return slots;
208 }
209
210 static inline struct z3fold_pool *slots_to_pool(struct z3fold_buddy_slots *s)
211 {
212         return (struct z3fold_pool *)(s->pool & ~HANDLE_FLAG_MASK);
213 }
214
215 static inline struct z3fold_buddy_slots *handle_to_slots(unsigned long handle)
216 {
217         return (struct z3fold_buddy_slots *)(handle & ~(SLOTS_ALIGN - 1));
218 }
219
220 /* Lock a z3fold page */
221 static inline void z3fold_page_lock(struct z3fold_header *zhdr)
222 {
223         spin_lock(&zhdr->page_lock);
224 }
225
226 /* Try to lock a z3fold page */
227 static inline int z3fold_page_trylock(struct z3fold_header *zhdr)
228 {
229         return spin_trylock(&zhdr->page_lock);
230 }
231
232 /* Unlock a z3fold page */
233 static inline void z3fold_page_unlock(struct z3fold_header *zhdr)
234 {
235         spin_unlock(&zhdr->page_lock);
236 }
237
238 /* return locked z3fold page if it's not headless */
239 static inline struct z3fold_header *get_z3fold_header(unsigned long handle)
240 {
241         struct z3fold_buddy_slots *slots;
242         struct z3fold_header *zhdr;
243         int locked = 0;
244
245         if (!(handle & (1 << PAGE_HEADLESS))) {
246                 slots = handle_to_slots(handle);
247                 do {
248                         unsigned long addr;
249
250                         read_lock(&slots->lock);
251                         addr = *(unsigned long *)handle;
252                         zhdr = (struct z3fold_header *)(addr & PAGE_MASK);
253                         locked = z3fold_page_trylock(zhdr);
254                         read_unlock(&slots->lock);
255                         if (locked) {
256                                 struct page *page = virt_to_page(zhdr);
257
258                                 if (!test_bit(PAGE_MIGRATED, &page->private))
259                                         break;
260                                 z3fold_page_unlock(zhdr);
261                         }
262                         cpu_relax();
263                 } while (true);
264         } else {
265                 zhdr = (struct z3fold_header *)(handle & PAGE_MASK);
266         }
267
268         return zhdr;
269 }
270
271 static inline void put_z3fold_header(struct z3fold_header *zhdr)
272 {
273         struct page *page = virt_to_page(zhdr);
274
275         if (!test_bit(PAGE_HEADLESS, &page->private))
276                 z3fold_page_unlock(zhdr);
277 }
278
279 static inline void free_handle(unsigned long handle, struct z3fold_header *zhdr)
280 {
281         struct z3fold_buddy_slots *slots;
282         int i;
283         bool is_free;
284
285         if (WARN_ON(*(unsigned long *)handle == 0))
286                 return;
287
288         slots = handle_to_slots(handle);
289         write_lock(&slots->lock);
290         *(unsigned long *)handle = 0;
291
292         if (test_bit(HANDLES_NOFREE, &slots->pool)) {
293                 write_unlock(&slots->lock);
294                 return; /* simple case, nothing else to do */
295         }
296
297         if (zhdr->slots != slots)
298                 zhdr->foreign_handles--;
299
300         is_free = true;
301         for (i = 0; i <= BUDDY_MASK; i++) {
302                 if (slots->slot[i]) {
303                         is_free = false;
304                         break;
305                 }
306         }
307         write_unlock(&slots->lock);
308
309         if (is_free) {
310                 struct z3fold_pool *pool = slots_to_pool(slots);
311
312                 if (zhdr->slots == slots)
313                         zhdr->slots = NULL;
314                 kmem_cache_free(pool->c_handle, slots);
315         }
316 }
317
318 /* Initializes the z3fold header of a newly allocated z3fold page */
319 static struct z3fold_header *init_z3fold_page(struct page *page, bool headless,
320                                         struct z3fold_pool *pool, gfp_t gfp)
321 {
322         struct z3fold_header *zhdr = page_address(page);
323         struct z3fold_buddy_slots *slots;
324
325         clear_bit(PAGE_HEADLESS, &page->private);
326         clear_bit(MIDDLE_CHUNK_MAPPED, &page->private);
327         clear_bit(NEEDS_COMPACTING, &page->private);
328         clear_bit(PAGE_STALE, &page->private);
329         clear_bit(PAGE_CLAIMED, &page->private);
330         clear_bit(PAGE_MIGRATED, &page->private);
331         if (headless)
332                 return zhdr;
333
334         slots = alloc_slots(pool, gfp);
335         if (!slots)
336                 return NULL;
337
338         memset(zhdr, 0, sizeof(*zhdr));
339         spin_lock_init(&zhdr->page_lock);
340         kref_init(&zhdr->refcount);
341         zhdr->cpu = -1;
342         zhdr->slots = slots;
343         zhdr->pool = pool;
344         INIT_LIST_HEAD(&zhdr->buddy);
345         INIT_WORK(&zhdr->work, compact_page_work);
346         return zhdr;
347 }
348
349 /* Resets the struct page fields and frees the page */
350 static void free_z3fold_page(struct page *page, bool headless)
351 {
352         if (!headless) {
353                 lock_page(page);
354                 __ClearPageMovable(page);
355                 unlock_page(page);
356         }
357         __free_page(page);
358 }
359
360 /* Helper function to build the index */
361 static inline int __idx(struct z3fold_header *zhdr, enum buddy bud)
362 {
363         return (bud + zhdr->first_num) & BUDDY_MASK;
364 }
365
366 /*
367  * Encodes the handle of a particular buddy within a z3fold page
368  * Pool lock should be held as this function accesses first_num
369  */
370 static unsigned long __encode_handle(struct z3fold_header *zhdr,
371                                 struct z3fold_buddy_slots *slots,
372                                 enum buddy bud)
373 {
374         unsigned long h = (unsigned long)zhdr;
375         int idx = 0;
376
377         /*
378          * For a headless page, its handle is its pointer with the extra
379          * PAGE_HEADLESS bit set
380          */
381         if (bud == HEADLESS)
382                 return h | (1 << PAGE_HEADLESS);
383
384         /* otherwise, return pointer to encoded handle */
385         idx = __idx(zhdr, bud);
386         h += idx;
387         if (bud == LAST)
388                 h |= (zhdr->last_chunks << BUDDY_SHIFT);
389
390         write_lock(&slots->lock);
391         slots->slot[idx] = h;
392         write_unlock(&slots->lock);
393         return (unsigned long)&slots->slot[idx];
394 }
395
396 static unsigned long encode_handle(struct z3fold_header *zhdr, enum buddy bud)
397 {
398         return __encode_handle(zhdr, zhdr->slots, bud);
399 }
400
401 /* only for LAST bud, returns zero otherwise */
402 static unsigned short handle_to_chunks(unsigned long handle)
403 {
404         struct z3fold_buddy_slots *slots = handle_to_slots(handle);
405         unsigned long addr;
406
407         read_lock(&slots->lock);
408         addr = *(unsigned long *)handle;
409         read_unlock(&slots->lock);
410         return (addr & ~PAGE_MASK) >> BUDDY_SHIFT;
411 }
412
413 /*
414  * (handle & BUDDY_MASK) < zhdr->first_num is possible in encode_handle
415  *  but that doesn't matter. because the masking will result in the
416  *  correct buddy number.
417  */
418 static enum buddy handle_to_buddy(unsigned long handle)
419 {
420         struct z3fold_header *zhdr;
421         struct z3fold_buddy_slots *slots = handle_to_slots(handle);
422         unsigned long addr;
423
424         read_lock(&slots->lock);
425         WARN_ON(handle & (1 << PAGE_HEADLESS));
426         addr = *(unsigned long *)handle;
427         read_unlock(&slots->lock);
428         zhdr = (struct z3fold_header *)(addr & PAGE_MASK);
429         return (addr - zhdr->first_num) & BUDDY_MASK;
430 }
431
432 static inline struct z3fold_pool *zhdr_to_pool(struct z3fold_header *zhdr)
433 {
434         return zhdr->pool;
435 }
436
437 static void __release_z3fold_page(struct z3fold_header *zhdr, bool locked)
438 {
439         struct page *page = virt_to_page(zhdr);
440         struct z3fold_pool *pool = zhdr_to_pool(zhdr);
441
442         WARN_ON(!list_empty(&zhdr->buddy));
443         set_bit(PAGE_STALE, &page->private);
444         clear_bit(NEEDS_COMPACTING, &page->private);
445         spin_lock(&pool->lock);
446         spin_unlock(&pool->lock);
447
448         if (locked)
449                 z3fold_page_unlock(zhdr);
450
451         spin_lock(&pool->stale_lock);
452         list_add(&zhdr->buddy, &pool->stale);
453         queue_work(pool->release_wq, &pool->work);
454         spin_unlock(&pool->stale_lock);
455
456         atomic64_dec(&pool->pages_nr);
457 }
458
459 static void release_z3fold_page_locked(struct kref *ref)
460 {
461         struct z3fold_header *zhdr = container_of(ref, struct z3fold_header,
462                                                 refcount);
463         WARN_ON(z3fold_page_trylock(zhdr));
464         __release_z3fold_page(zhdr, true);
465 }
466
467 static void release_z3fold_page_locked_list(struct kref *ref)
468 {
469         struct z3fold_header *zhdr = container_of(ref, struct z3fold_header,
470                                                refcount);
471         struct z3fold_pool *pool = zhdr_to_pool(zhdr);
472
473         spin_lock(&pool->lock);
474         list_del_init(&zhdr->buddy);
475         spin_unlock(&pool->lock);
476
477         WARN_ON(z3fold_page_trylock(zhdr));
478         __release_z3fold_page(zhdr, true);
479 }
480
481 static inline int put_z3fold_locked(struct z3fold_header *zhdr)
482 {
483         return kref_put(&zhdr->refcount, release_z3fold_page_locked);
484 }
485
486 static inline int put_z3fold_locked_list(struct z3fold_header *zhdr)
487 {
488         return kref_put(&zhdr->refcount, release_z3fold_page_locked_list);
489 }
490
491 static 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  */
517 static 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 */
538 static 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
556 static 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
578 static 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
587 static 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
594 static 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
676 out_fail:
677         if (new_zhdr && !put_z3fold_locked(new_zhdr)) {
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 */
687 static 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
734 static 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 (put_z3fold_locked(zhdr))
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 (!put_z3fold_locked(zhdr)) {
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
776 static 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 */
785 static 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
793 lookup:
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
888 out_fail:
889         if (!put_z3fold_locked(zhdr)) {
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  */
908 static 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->stale);
934         atomic64_set(&pool->pages_nr, 0);
935         pool->name = name;
936         pool->compact_wq = create_singlethread_workqueue(pool->name);
937         if (!pool->compact_wq)
938                 goto out_unbuddied;
939         pool->release_wq = create_singlethread_workqueue(pool->name);
940         if (!pool->release_wq)
941                 goto out_wq;
942         INIT_WORK(&pool->work, free_pages_work);
943         return pool;
944
945 out_wq:
946         destroy_workqueue(pool->compact_wq);
947 out_unbuddied:
948         free_percpu(pool->unbuddied);
949 out_pool:
950         kmem_cache_destroy(pool->c_handle);
951 out_c:
952         kfree(pool);
953 out:
954         return NULL;
955 }
956
957 /**
958  * z3fold_destroy_pool() - destroys an existing z3fold pool
959  * @pool:       the z3fold pool to be destroyed
960  *
961  * The pool should be emptied before this function is called.
962  */
963 static void z3fold_destroy_pool(struct z3fold_pool *pool)
964 {
965         kmem_cache_destroy(pool->c_handle);
966
967         /*
968          * We need to destroy pool->compact_wq before pool->release_wq,
969          * as any pending work on pool->compact_wq will call
970          * queue_work(pool->release_wq, &pool->work).
971          *
972          * There are still outstanding pages until both workqueues are drained,
973          * so we cannot unregister migration until then.
974          */
975
976         destroy_workqueue(pool->compact_wq);
977         destroy_workqueue(pool->release_wq);
978         free_percpu(pool->unbuddied);
979         kfree(pool);
980 }
981
982 static const struct movable_operations z3fold_mops;
983
984 /**
985  * z3fold_alloc() - allocates a region of a given size
986  * @pool:       z3fold pool from which to allocate
987  * @size:       size in bytes of the desired allocation
988  * @gfp:        gfp flags used if the pool needs to grow
989  * @handle:     handle of the new allocation
990  *
991  * This function will attempt to find a free region in the pool large enough to
992  * satisfy the allocation request.  A search of the unbuddied lists is
993  * performed first. If no suitable free region is found, then a new page is
994  * allocated and added to the pool to satisfy the request.
995  *
996  * Return: 0 if success and handle is set, otherwise -EINVAL if the size or
997  * gfp arguments are invalid or -ENOMEM if the pool was unable to allocate
998  * a new page.
999  */
1000 static int z3fold_alloc(struct z3fold_pool *pool, size_t size, gfp_t gfp,
1001                         unsigned long *handle)
1002 {
1003         int chunks = size_to_chunks(size);
1004         struct z3fold_header *zhdr = NULL;
1005         struct page *page = NULL;
1006         enum buddy bud;
1007         bool can_sleep = gfpflags_allow_blocking(gfp);
1008
1009         if (!size || (gfp & __GFP_HIGHMEM))
1010                 return -EINVAL;
1011
1012         if (size > PAGE_SIZE)
1013                 return -ENOSPC;
1014
1015         if (size > PAGE_SIZE - ZHDR_SIZE_ALIGNED - CHUNK_SIZE)
1016                 bud = HEADLESS;
1017         else {
1018 retry:
1019                 zhdr = __z3fold_alloc(pool, size, can_sleep);
1020                 if (zhdr) {
1021                         bud = get_free_buddy(zhdr, chunks);
1022                         if (bud == HEADLESS) {
1023                                 if (!put_z3fold_locked(zhdr))
1024                                         z3fold_page_unlock(zhdr);
1025                                 pr_err("No free chunks in unbuddied\n");
1026                                 WARN_ON(1);
1027                                 goto retry;
1028                         }
1029                         page = virt_to_page(zhdr);
1030                         goto found;
1031                 }
1032                 bud = FIRST;
1033         }
1034
1035         page = alloc_page(gfp);
1036         if (!page)
1037                 return -ENOMEM;
1038
1039         zhdr = init_z3fold_page(page, bud == HEADLESS, pool, gfp);
1040         if (!zhdr) {
1041                 __free_page(page);
1042                 return -ENOMEM;
1043         }
1044         atomic64_inc(&pool->pages_nr);
1045
1046         if (bud == HEADLESS) {
1047                 set_bit(PAGE_HEADLESS, &page->private);
1048                 goto headless;
1049         }
1050         if (can_sleep) {
1051                 lock_page(page);
1052                 __SetPageMovable(page, &z3fold_mops);
1053                 unlock_page(page);
1054         } else {
1055                 WARN_ON(!trylock_page(page));
1056                 __SetPageMovable(page, &z3fold_mops);
1057                 unlock_page(page);
1058         }
1059         z3fold_page_lock(zhdr);
1060
1061 found:
1062         if (bud == FIRST)
1063                 zhdr->first_chunks = chunks;
1064         else if (bud == LAST)
1065                 zhdr->last_chunks = chunks;
1066         else {
1067                 zhdr->middle_chunks = chunks;
1068                 zhdr->start_middle = zhdr->first_chunks + ZHDR_CHUNKS;
1069         }
1070         add_to_unbuddied(pool, zhdr);
1071
1072 headless:
1073         spin_lock(&pool->lock);
1074         *handle = encode_handle(zhdr, bud);
1075         spin_unlock(&pool->lock);
1076         if (bud != HEADLESS)
1077                 z3fold_page_unlock(zhdr);
1078
1079         return 0;
1080 }
1081
1082 /**
1083  * z3fold_free() - frees the allocation associated with the given handle
1084  * @pool:       pool in which the allocation resided
1085  * @handle:     handle associated with the allocation returned by z3fold_alloc()
1086  *
1087  * In the case that the z3fold page in which the allocation resides is under
1088  * reclaim, as indicated by the PAGE_CLAIMED flag being set, this function
1089  * only sets the first|middle|last_chunks to 0.  The page is actually freed
1090  * once all buddies are evicted (see z3fold_reclaim_page() below).
1091  */
1092 static void z3fold_free(struct z3fold_pool *pool, unsigned long handle)
1093 {
1094         struct z3fold_header *zhdr;
1095         struct page *page;
1096         enum buddy bud;
1097         bool page_claimed;
1098
1099         zhdr = get_z3fold_header(handle);
1100         page = virt_to_page(zhdr);
1101         page_claimed = test_and_set_bit(PAGE_CLAIMED, &page->private);
1102
1103         if (test_bit(PAGE_HEADLESS, &page->private)) {
1104                 /* if a headless page is under reclaim, just leave.
1105                  * NB: we use test_and_set_bit for a reason: if the bit
1106                  * has not been set before, we release this page
1107                  * immediately so we don't care about its value any more.
1108                  */
1109                 if (!page_claimed) {
1110                         put_z3fold_header(zhdr);
1111                         free_z3fold_page(page, true);
1112                         atomic64_dec(&pool->pages_nr);
1113                 }
1114                 return;
1115         }
1116
1117         /* Non-headless case */
1118         bud = handle_to_buddy(handle);
1119
1120         switch (bud) {
1121         case FIRST:
1122                 zhdr->first_chunks = 0;
1123                 break;
1124         case MIDDLE:
1125                 zhdr->middle_chunks = 0;
1126                 break;
1127         case LAST:
1128                 zhdr->last_chunks = 0;
1129                 break;
1130         default:
1131                 pr_err("%s: unknown bud %d\n", __func__, bud);
1132                 WARN_ON(1);
1133                 put_z3fold_header(zhdr);
1134                 return;
1135         }
1136
1137         if (!page_claimed)
1138                 free_handle(handle, zhdr);
1139         if (put_z3fold_locked_list(zhdr))
1140                 return;
1141         if (page_claimed) {
1142                 /* the page has not been claimed by us */
1143                 put_z3fold_header(zhdr);
1144                 return;
1145         }
1146         if (test_and_set_bit(NEEDS_COMPACTING, &page->private)) {
1147                 clear_bit(PAGE_CLAIMED, &page->private);
1148                 put_z3fold_header(zhdr);
1149                 return;
1150         }
1151         if (zhdr->cpu < 0 || !cpu_online(zhdr->cpu)) {
1152                 zhdr->cpu = -1;
1153                 kref_get(&zhdr->refcount);
1154                 clear_bit(PAGE_CLAIMED, &page->private);
1155                 do_compact_page(zhdr, true);
1156                 return;
1157         }
1158         kref_get(&zhdr->refcount);
1159         clear_bit(PAGE_CLAIMED, &page->private);
1160         queue_work_on(zhdr->cpu, pool->compact_wq, &zhdr->work);
1161         put_z3fold_header(zhdr);
1162 }
1163
1164 /**
1165  * z3fold_map() - maps the allocation associated with the given handle
1166  * @pool:       pool in which the allocation resides
1167  * @handle:     handle associated with the allocation to be mapped
1168  *
1169  * Extracts the buddy number from handle and constructs the pointer to the
1170  * correct starting chunk within the page.
1171  *
1172  * Returns: a pointer to the mapped allocation
1173  */
1174 static void *z3fold_map(struct z3fold_pool *pool, unsigned long handle)
1175 {
1176         struct z3fold_header *zhdr;
1177         struct page *page;
1178         void *addr;
1179         enum buddy buddy;
1180
1181         zhdr = get_z3fold_header(handle);
1182         addr = zhdr;
1183         page = virt_to_page(zhdr);
1184
1185         if (test_bit(PAGE_HEADLESS, &page->private))
1186                 goto out;
1187
1188         buddy = handle_to_buddy(handle);
1189         switch (buddy) {
1190         case FIRST:
1191                 addr += ZHDR_SIZE_ALIGNED;
1192                 break;
1193         case MIDDLE:
1194                 addr += zhdr->start_middle << CHUNK_SHIFT;
1195                 set_bit(MIDDLE_CHUNK_MAPPED, &page->private);
1196                 break;
1197         case LAST:
1198                 addr += PAGE_SIZE - (handle_to_chunks(handle) << CHUNK_SHIFT);
1199                 break;
1200         default:
1201                 pr_err("unknown buddy id %d\n", buddy);
1202                 WARN_ON(1);
1203                 addr = NULL;
1204                 break;
1205         }
1206
1207         if (addr)
1208                 zhdr->mapped_count++;
1209 out:
1210         put_z3fold_header(zhdr);
1211         return addr;
1212 }
1213
1214 /**
1215  * z3fold_unmap() - unmaps the allocation associated with the given handle
1216  * @pool:       pool in which the allocation resides
1217  * @handle:     handle associated with the allocation to be unmapped
1218  */
1219 static void z3fold_unmap(struct z3fold_pool *pool, unsigned long handle)
1220 {
1221         struct z3fold_header *zhdr;
1222         struct page *page;
1223         enum buddy buddy;
1224
1225         zhdr = get_z3fold_header(handle);
1226         page = virt_to_page(zhdr);
1227
1228         if (test_bit(PAGE_HEADLESS, &page->private))
1229                 return;
1230
1231         buddy = handle_to_buddy(handle);
1232         if (buddy == MIDDLE)
1233                 clear_bit(MIDDLE_CHUNK_MAPPED, &page->private);
1234         zhdr->mapped_count--;
1235         put_z3fold_header(zhdr);
1236 }
1237
1238 /**
1239  * z3fold_get_pool_size() - gets the z3fold pool size in pages
1240  * @pool:       pool whose size is being queried
1241  *
1242  * Returns: size in pages of the given pool.
1243  */
1244 static u64 z3fold_get_pool_size(struct z3fold_pool *pool)
1245 {
1246         return atomic64_read(&pool->pages_nr);
1247 }
1248
1249 static bool z3fold_page_isolate(struct page *page, isolate_mode_t mode)
1250 {
1251         struct z3fold_header *zhdr;
1252         struct z3fold_pool *pool;
1253
1254         VM_BUG_ON_PAGE(PageIsolated(page), page);
1255
1256         if (test_bit(PAGE_HEADLESS, &page->private))
1257                 return false;
1258
1259         zhdr = page_address(page);
1260         z3fold_page_lock(zhdr);
1261         if (test_bit(NEEDS_COMPACTING, &page->private) ||
1262             test_bit(PAGE_STALE, &page->private))
1263                 goto out;
1264
1265         if (zhdr->mapped_count != 0 || zhdr->foreign_handles != 0)
1266                 goto out;
1267
1268         if (test_and_set_bit(PAGE_CLAIMED, &page->private))
1269                 goto out;
1270         pool = zhdr_to_pool(zhdr);
1271         spin_lock(&pool->lock);
1272         if (!list_empty(&zhdr->buddy))
1273                 list_del_init(&zhdr->buddy);
1274         spin_unlock(&pool->lock);
1275
1276         kref_get(&zhdr->refcount);
1277         z3fold_page_unlock(zhdr);
1278         return true;
1279
1280 out:
1281         z3fold_page_unlock(zhdr);
1282         return false;
1283 }
1284
1285 static int z3fold_page_migrate(struct page *newpage, struct page *page,
1286                 enum migrate_mode mode)
1287 {
1288         struct z3fold_header *zhdr, *new_zhdr;
1289         struct z3fold_pool *pool;
1290
1291         VM_BUG_ON_PAGE(!PageIsolated(page), page);
1292         VM_BUG_ON_PAGE(!test_bit(PAGE_CLAIMED, &page->private), page);
1293         VM_BUG_ON_PAGE(!PageLocked(newpage), newpage);
1294
1295         zhdr = page_address(page);
1296         pool = zhdr_to_pool(zhdr);
1297
1298         if (!z3fold_page_trylock(zhdr))
1299                 return -EAGAIN;
1300         if (zhdr->mapped_count != 0 || zhdr->foreign_handles != 0) {
1301                 clear_bit(PAGE_CLAIMED, &page->private);
1302                 z3fold_page_unlock(zhdr);
1303                 return -EBUSY;
1304         }
1305         if (work_pending(&zhdr->work)) {
1306                 z3fold_page_unlock(zhdr);
1307                 return -EAGAIN;
1308         }
1309         new_zhdr = page_address(newpage);
1310         memcpy(new_zhdr, zhdr, PAGE_SIZE);
1311         newpage->private = page->private;
1312         set_bit(PAGE_MIGRATED, &page->private);
1313         z3fold_page_unlock(zhdr);
1314         spin_lock_init(&new_zhdr->page_lock);
1315         INIT_WORK(&new_zhdr->work, compact_page_work);
1316         /*
1317          * z3fold_page_isolate() ensures that new_zhdr->buddy is empty,
1318          * so we only have to reinitialize it.
1319          */
1320         INIT_LIST_HEAD(&new_zhdr->buddy);
1321         __ClearPageMovable(page);
1322
1323         get_page(newpage);
1324         z3fold_page_lock(new_zhdr);
1325         if (new_zhdr->first_chunks)
1326                 encode_handle(new_zhdr, FIRST);
1327         if (new_zhdr->last_chunks)
1328                 encode_handle(new_zhdr, LAST);
1329         if (new_zhdr->middle_chunks)
1330                 encode_handle(new_zhdr, MIDDLE);
1331         set_bit(NEEDS_COMPACTING, &newpage->private);
1332         new_zhdr->cpu = smp_processor_id();
1333         __SetPageMovable(newpage, &z3fold_mops);
1334         z3fold_page_unlock(new_zhdr);
1335
1336         queue_work_on(new_zhdr->cpu, pool->compact_wq, &new_zhdr->work);
1337
1338         /* PAGE_CLAIMED and PAGE_MIGRATED are cleared now. */
1339         page->private = 0;
1340         put_page(page);
1341         return 0;
1342 }
1343
1344 static void z3fold_page_putback(struct page *page)
1345 {
1346         struct z3fold_header *zhdr;
1347         struct z3fold_pool *pool;
1348
1349         zhdr = page_address(page);
1350         pool = zhdr_to_pool(zhdr);
1351
1352         z3fold_page_lock(zhdr);
1353         if (!list_empty(&zhdr->buddy))
1354                 list_del_init(&zhdr->buddy);
1355         INIT_LIST_HEAD(&page->lru);
1356         if (put_z3fold_locked(zhdr))
1357                 return;
1358         if (list_empty(&zhdr->buddy))
1359                 add_to_unbuddied(pool, zhdr);
1360         clear_bit(PAGE_CLAIMED, &page->private);
1361         z3fold_page_unlock(zhdr);
1362 }
1363
1364 static const struct movable_operations z3fold_mops = {
1365         .isolate_page = z3fold_page_isolate,
1366         .migrate_page = z3fold_page_migrate,
1367         .putback_page = z3fold_page_putback,
1368 };
1369
1370 /*****************
1371  * zpool
1372  ****************/
1373
1374 static void *z3fold_zpool_create(const char *name, gfp_t gfp)
1375 {
1376         return z3fold_create_pool(name, gfp);
1377 }
1378
1379 static void z3fold_zpool_destroy(void *pool)
1380 {
1381         z3fold_destroy_pool(pool);
1382 }
1383
1384 static int z3fold_zpool_malloc(void *pool, size_t size, gfp_t gfp,
1385                         unsigned long *handle)
1386 {
1387         return z3fold_alloc(pool, size, gfp, handle);
1388 }
1389 static void z3fold_zpool_free(void *pool, unsigned long handle)
1390 {
1391         z3fold_free(pool, handle);
1392 }
1393
1394 static void *z3fold_zpool_map(void *pool, unsigned long handle,
1395                         enum zpool_mapmode mm)
1396 {
1397         return z3fold_map(pool, handle);
1398 }
1399 static void z3fold_zpool_unmap(void *pool, unsigned long handle)
1400 {
1401         z3fold_unmap(pool, handle);
1402 }
1403
1404 static u64 z3fold_zpool_total_size(void *pool)
1405 {
1406         return z3fold_get_pool_size(pool) * PAGE_SIZE;
1407 }
1408
1409 static struct zpool_driver z3fold_zpool_driver = {
1410         .type =         "z3fold",
1411         .sleep_mapped = true,
1412         .owner =        THIS_MODULE,
1413         .create =       z3fold_zpool_create,
1414         .destroy =      z3fold_zpool_destroy,
1415         .malloc =       z3fold_zpool_malloc,
1416         .free =         z3fold_zpool_free,
1417         .map =          z3fold_zpool_map,
1418         .unmap =        z3fold_zpool_unmap,
1419         .total_size =   z3fold_zpool_total_size,
1420 };
1421
1422 MODULE_ALIAS("zpool-z3fold");
1423
1424 static int __init init_z3fold(void)
1425 {
1426         /*
1427          * Make sure the z3fold header is not larger than the page size and
1428          * there has remaining spaces for its buddy.
1429          */
1430         BUILD_BUG_ON(ZHDR_SIZE_ALIGNED > PAGE_SIZE - CHUNK_SIZE);
1431         zpool_register_driver(&z3fold_zpool_driver);
1432
1433         return 0;
1434 }
1435
1436 static void __exit exit_z3fold(void)
1437 {
1438         zpool_unregister_driver(&z3fold_zpool_driver);
1439 }
1440
1441 module_init(init_z3fold);
1442 module_exit(exit_z3fold);
1443
1444 MODULE_LICENSE("GPL");
1445 MODULE_AUTHOR("Vitaly Wool <vitalywool@gmail.com>");
1446 MODULE_DESCRIPTION("3-Fold Allocator for Compressed Pages");