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09c434b8 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
9a001fc1 VW |
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> | |
d30561c5 | 27 | #include <linux/sched.h> |
1f862989 VW |
28 | #include <linux/cpumask.h> |
29 | #include <linux/dcache.h> | |
9a001fc1 VW |
30 | #include <linux/list.h> |
31 | #include <linux/mm.h> | |
32 | #include <linux/module.h> | |
1f862989 VW |
33 | #include <linux/page-flags.h> |
34 | #include <linux/migrate.h> | |
35 | #include <linux/node.h> | |
36 | #include <linux/compaction.h> | |
d30561c5 | 37 | #include <linux/percpu.h> |
1f862989 VW |
38 | #include <linux/mount.h> |
39 | #include <linux/fs.h> | |
9a001fc1 | 40 | #include <linux/preempt.h> |
d30561c5 | 41 | #include <linux/workqueue.h> |
9a001fc1 VW |
42 | #include <linux/slab.h> |
43 | #include <linux/spinlock.h> | |
44 | #include <linux/zpool.h> | |
45 | ||
7c2b8baa VW |
46 | /* |
47 | * NCHUNKS_ORDER determines the internal allocation granularity, effectively | |
48 | * adjusting internal fragmentation. It also determines the number of | |
49 | * freelists maintained in each pool. NCHUNKS_ORDER of 6 means that the | |
50 | * allocation granularity will be in chunks of size PAGE_SIZE/64. Some chunks | |
51 | * in the beginning of an allocated page are occupied by z3fold header, so | |
52 | * NCHUNKS will be calculated to 63 (or 62 in case CONFIG_DEBUG_SPINLOCK=y), | |
53 | * which shows the max number of free chunks in z3fold page, also there will | |
54 | * be 63, or 62, respectively, freelists per pool. | |
55 | */ | |
56 | #define NCHUNKS_ORDER 6 | |
57 | ||
58 | #define CHUNK_SHIFT (PAGE_SHIFT - NCHUNKS_ORDER) | |
59 | #define CHUNK_SIZE (1 << CHUNK_SHIFT) | |
60 | #define ZHDR_SIZE_ALIGNED round_up(sizeof(struct z3fold_header), CHUNK_SIZE) | |
61 | #define ZHDR_CHUNKS (ZHDR_SIZE_ALIGNED >> CHUNK_SHIFT) | |
62 | #define TOTAL_CHUNKS (PAGE_SIZE >> CHUNK_SHIFT) | |
63 | #define NCHUNKS ((PAGE_SIZE - ZHDR_SIZE_ALIGNED) >> CHUNK_SHIFT) | |
64 | ||
65 | #define BUDDY_MASK (0x3) | |
66 | #define BUDDY_SHIFT 2 | |
67 | #define SLOTS_ALIGN (0x40) | |
68 | ||
9a001fc1 VW |
69 | /***************** |
70 | * Structures | |
71 | *****************/ | |
ede93213 VW |
72 | struct z3fold_pool; |
73 | struct z3fold_ops { | |
74 | int (*evict)(struct z3fold_pool *pool, unsigned long handle); | |
75 | }; | |
76 | ||
77 | enum buddy { | |
78 | HEADLESS = 0, | |
79 | FIRST, | |
80 | MIDDLE, | |
81 | LAST, | |
7c2b8baa VW |
82 | BUDDIES_MAX = LAST |
83 | }; | |
84 | ||
85 | struct z3fold_buddy_slots { | |
86 | /* | |
87 | * we are using BUDDY_MASK in handle_to_buddy etc. so there should | |
88 | * be enough slots to hold all possible variants | |
89 | */ | |
90 | unsigned long slot[BUDDY_MASK + 1]; | |
91 | unsigned long pool; /* back link + flags */ | |
ede93213 | 92 | }; |
7c2b8baa | 93 | #define HANDLE_FLAG_MASK (0x03) |
ede93213 VW |
94 | |
95 | /* | |
d30561c5 | 96 | * struct z3fold_header - z3fold page metadata occupying first chunks of each |
ede93213 | 97 | * z3fold page, except for HEADLESS pages |
d30561c5 VW |
98 | * @buddy: links the z3fold page into the relevant list in the |
99 | * pool | |
2f1e5e4d | 100 | * @page_lock: per-page lock |
d30561c5 VW |
101 | * @refcount: reference count for the z3fold page |
102 | * @work: work_struct for page layout optimization | |
7c2b8baa | 103 | * @slots: pointer to the structure holding buddy slots |
d30561c5 | 104 | * @cpu: CPU which this page "belongs" to |
ede93213 VW |
105 | * @first_chunks: the size of the first buddy in chunks, 0 if free |
106 | * @middle_chunks: the size of the middle buddy in chunks, 0 if free | |
107 | * @last_chunks: the size of the last buddy in chunks, 0 if free | |
108 | * @first_num: the starting number (for the first handle) | |
1f862989 | 109 | * @mapped_count: the number of objects currently mapped |
ede93213 VW |
110 | */ |
111 | struct z3fold_header { | |
112 | struct list_head buddy; | |
2f1e5e4d | 113 | spinlock_t page_lock; |
5a27aa82 | 114 | struct kref refcount; |
d30561c5 | 115 | struct work_struct work; |
7c2b8baa | 116 | struct z3fold_buddy_slots *slots; |
d30561c5 | 117 | short cpu; |
ede93213 VW |
118 | unsigned short first_chunks; |
119 | unsigned short middle_chunks; | |
120 | unsigned short last_chunks; | |
121 | unsigned short start_middle; | |
122 | unsigned short first_num:2; | |
1f862989 | 123 | unsigned short mapped_count:2; |
ede93213 VW |
124 | }; |
125 | ||
9a001fc1 VW |
126 | /** |
127 | * struct z3fold_pool - stores metadata for each z3fold pool | |
d30561c5 VW |
128 | * @name: pool name |
129 | * @lock: protects pool unbuddied/lru lists | |
130 | * @stale_lock: protects pool stale page list | |
131 | * @unbuddied: per-cpu array of lists tracking z3fold pages that contain 2- | |
132 | * buddies; the list each z3fold page is added to depends on | |
133 | * the size of its free region. | |
9a001fc1 VW |
134 | * @lru: list tracking the z3fold pages in LRU order by most recently |
135 | * added buddy. | |
d30561c5 | 136 | * @stale: list of pages marked for freeing |
9a001fc1 | 137 | * @pages_nr: number of z3fold pages in the pool. |
7c2b8baa | 138 | * @c_handle: cache for z3fold_buddy_slots allocation |
9a001fc1 VW |
139 | * @ops: pointer to a structure of user defined operations specified at |
140 | * pool creation time. | |
d30561c5 VW |
141 | * @compact_wq: workqueue for page layout background optimization |
142 | * @release_wq: workqueue for safe page release | |
143 | * @work: work_struct for safe page release | |
1f862989 | 144 | * @inode: inode for z3fold pseudo filesystem |
9a001fc1 VW |
145 | * |
146 | * This structure is allocated at pool creation time and maintains metadata | |
147 | * pertaining to a particular z3fold pool. | |
148 | */ | |
149 | struct z3fold_pool { | |
d30561c5 | 150 | const char *name; |
9a001fc1 | 151 | spinlock_t lock; |
d30561c5 VW |
152 | spinlock_t stale_lock; |
153 | struct list_head *unbuddied; | |
9a001fc1 | 154 | struct list_head lru; |
d30561c5 | 155 | struct list_head stale; |
12d59ae6 | 156 | atomic64_t pages_nr; |
7c2b8baa | 157 | struct kmem_cache *c_handle; |
9a001fc1 VW |
158 | const struct z3fold_ops *ops; |
159 | struct zpool *zpool; | |
160 | const struct zpool_ops *zpool_ops; | |
d30561c5 VW |
161 | struct workqueue_struct *compact_wq; |
162 | struct workqueue_struct *release_wq; | |
163 | struct work_struct work; | |
1f862989 | 164 | struct inode *inode; |
9a001fc1 VW |
165 | }; |
166 | ||
9a001fc1 VW |
167 | /* |
168 | * Internal z3fold page flags | |
169 | */ | |
170 | enum z3fold_page_flags { | |
5a27aa82 | 171 | PAGE_HEADLESS = 0, |
9a001fc1 | 172 | MIDDLE_CHUNK_MAPPED, |
d30561c5 | 173 | NEEDS_COMPACTING, |
6098d7e1 | 174 | PAGE_STALE, |
ca0246bb | 175 | PAGE_CLAIMED, /* by either reclaim or free */ |
9a001fc1 VW |
176 | }; |
177 | ||
178 | /***************** | |
179 | * Helpers | |
180 | *****************/ | |
181 | ||
182 | /* Converts an allocation size in bytes to size in z3fold chunks */ | |
183 | static int size_to_chunks(size_t size) | |
184 | { | |
185 | return (size + CHUNK_SIZE - 1) >> CHUNK_SHIFT; | |
186 | } | |
187 | ||
188 | #define for_each_unbuddied_list(_iter, _begin) \ | |
189 | for ((_iter) = (_begin); (_iter) < NCHUNKS; (_iter)++) | |
190 | ||
d30561c5 VW |
191 | static void compact_page_work(struct work_struct *w); |
192 | ||
7c2b8baa VW |
193 | static inline struct z3fold_buddy_slots *alloc_slots(struct z3fold_pool *pool) |
194 | { | |
195 | struct z3fold_buddy_slots *slots = kmem_cache_alloc(pool->c_handle, | |
196 | GFP_KERNEL); | |
197 | ||
198 | if (slots) { | |
199 | memset(slots->slot, 0, sizeof(slots->slot)); | |
200 | slots->pool = (unsigned long)pool; | |
201 | } | |
202 | ||
203 | return slots; | |
204 | } | |
205 | ||
206 | static inline struct z3fold_pool *slots_to_pool(struct z3fold_buddy_slots *s) | |
207 | { | |
208 | return (struct z3fold_pool *)(s->pool & ~HANDLE_FLAG_MASK); | |
209 | } | |
210 | ||
211 | static inline struct z3fold_buddy_slots *handle_to_slots(unsigned long handle) | |
212 | { | |
213 | return (struct z3fold_buddy_slots *)(handle & ~(SLOTS_ALIGN - 1)); | |
214 | } | |
215 | ||
216 | static inline void free_handle(unsigned long handle) | |
217 | { | |
218 | struct z3fold_buddy_slots *slots; | |
219 | int i; | |
220 | bool is_free; | |
221 | ||
222 | if (handle & (1 << PAGE_HEADLESS)) | |
223 | return; | |
224 | ||
225 | WARN_ON(*(unsigned long *)handle == 0); | |
226 | *(unsigned long *)handle = 0; | |
227 | slots = handle_to_slots(handle); | |
228 | is_free = true; | |
229 | for (i = 0; i <= BUDDY_MASK; i++) { | |
230 | if (slots->slot[i]) { | |
231 | is_free = false; | |
232 | break; | |
233 | } | |
234 | } | |
235 | ||
236 | if (is_free) { | |
237 | struct z3fold_pool *pool = slots_to_pool(slots); | |
238 | ||
239 | kmem_cache_free(pool->c_handle, slots); | |
240 | } | |
241 | } | |
242 | ||
1f862989 VW |
243 | static struct dentry *z3fold_do_mount(struct file_system_type *fs_type, |
244 | int flags, const char *dev_name, void *data) | |
245 | { | |
246 | static const struct dentry_operations ops = { | |
247 | .d_dname = simple_dname, | |
248 | }; | |
249 | ||
250 | return mount_pseudo(fs_type, "z3fold:", NULL, &ops, 0x33); | |
251 | } | |
252 | ||
253 | static struct file_system_type z3fold_fs = { | |
254 | .name = "z3fold", | |
255 | .mount = z3fold_do_mount, | |
256 | .kill_sb = kill_anon_super, | |
257 | }; | |
258 | ||
259 | static struct vfsmount *z3fold_mnt; | |
260 | static int z3fold_mount(void) | |
261 | { | |
262 | int ret = 0; | |
263 | ||
264 | z3fold_mnt = kern_mount(&z3fold_fs); | |
265 | if (IS_ERR(z3fold_mnt)) | |
266 | ret = PTR_ERR(z3fold_mnt); | |
267 | ||
268 | return ret; | |
269 | } | |
270 | ||
271 | static void z3fold_unmount(void) | |
272 | { | |
273 | kern_unmount(z3fold_mnt); | |
274 | } | |
275 | ||
276 | static const struct address_space_operations z3fold_aops; | |
277 | static int z3fold_register_migration(struct z3fold_pool *pool) | |
278 | { | |
279 | pool->inode = alloc_anon_inode(z3fold_mnt->mnt_sb); | |
280 | if (IS_ERR(pool->inode)) { | |
281 | pool->inode = NULL; | |
282 | return 1; | |
283 | } | |
284 | ||
285 | pool->inode->i_mapping->private_data = pool; | |
286 | pool->inode->i_mapping->a_ops = &z3fold_aops; | |
287 | return 0; | |
288 | } | |
289 | ||
290 | static void z3fold_unregister_migration(struct z3fold_pool *pool) | |
291 | { | |
292 | if (pool->inode) | |
293 | iput(pool->inode); | |
294 | } | |
295 | ||
9a001fc1 | 296 | /* Initializes the z3fold header of a newly allocated z3fold page */ |
d30561c5 VW |
297 | static struct z3fold_header *init_z3fold_page(struct page *page, |
298 | struct z3fold_pool *pool) | |
9a001fc1 VW |
299 | { |
300 | struct z3fold_header *zhdr = page_address(page); | |
7c2b8baa VW |
301 | struct z3fold_buddy_slots *slots = alloc_slots(pool); |
302 | ||
303 | if (!slots) | |
304 | return NULL; | |
9a001fc1 VW |
305 | |
306 | INIT_LIST_HEAD(&page->lru); | |
9a001fc1 VW |
307 | clear_bit(PAGE_HEADLESS, &page->private); |
308 | clear_bit(MIDDLE_CHUNK_MAPPED, &page->private); | |
d30561c5 VW |
309 | clear_bit(NEEDS_COMPACTING, &page->private); |
310 | clear_bit(PAGE_STALE, &page->private); | |
ca0246bb | 311 | clear_bit(PAGE_CLAIMED, &page->private); |
9a001fc1 | 312 | |
2f1e5e4d | 313 | spin_lock_init(&zhdr->page_lock); |
5a27aa82 | 314 | kref_init(&zhdr->refcount); |
9a001fc1 VW |
315 | zhdr->first_chunks = 0; |
316 | zhdr->middle_chunks = 0; | |
317 | zhdr->last_chunks = 0; | |
318 | zhdr->first_num = 0; | |
319 | zhdr->start_middle = 0; | |
d30561c5 | 320 | zhdr->cpu = -1; |
7c2b8baa | 321 | zhdr->slots = slots; |
9a001fc1 | 322 | INIT_LIST_HEAD(&zhdr->buddy); |
d30561c5 | 323 | INIT_WORK(&zhdr->work, compact_page_work); |
9a001fc1 VW |
324 | return zhdr; |
325 | } | |
326 | ||
327 | /* Resets the struct page fields and frees the page */ | |
1f862989 | 328 | static void free_z3fold_page(struct page *page, bool headless) |
9a001fc1 | 329 | { |
1f862989 VW |
330 | if (!headless) { |
331 | lock_page(page); | |
332 | __ClearPageMovable(page); | |
333 | unlock_page(page); | |
334 | } | |
335 | ClearPagePrivate(page); | |
5a27aa82 VW |
336 | __free_page(page); |
337 | } | |
338 | ||
2f1e5e4d VW |
339 | /* Lock a z3fold page */ |
340 | static inline void z3fold_page_lock(struct z3fold_header *zhdr) | |
341 | { | |
342 | spin_lock(&zhdr->page_lock); | |
343 | } | |
344 | ||
76e32a2a VW |
345 | /* Try to lock a z3fold page */ |
346 | static inline int z3fold_page_trylock(struct z3fold_header *zhdr) | |
347 | { | |
348 | return spin_trylock(&zhdr->page_lock); | |
349 | } | |
350 | ||
2f1e5e4d VW |
351 | /* Unlock a z3fold page */ |
352 | static inline void z3fold_page_unlock(struct z3fold_header *zhdr) | |
353 | { | |
354 | spin_unlock(&zhdr->page_lock); | |
355 | } | |
356 | ||
7c2b8baa VW |
357 | /* Helper function to build the index */ |
358 | static inline int __idx(struct z3fold_header *zhdr, enum buddy bud) | |
359 | { | |
360 | return (bud + zhdr->first_num) & BUDDY_MASK; | |
361 | } | |
362 | ||
9a001fc1 VW |
363 | /* |
364 | * Encodes the handle of a particular buddy within a z3fold page | |
365 | * Pool lock should be held as this function accesses first_num | |
366 | */ | |
367 | static unsigned long encode_handle(struct z3fold_header *zhdr, enum buddy bud) | |
368 | { | |
7c2b8baa VW |
369 | struct z3fold_buddy_slots *slots; |
370 | unsigned long h = (unsigned long)zhdr; | |
371 | int idx = 0; | |
9a001fc1 | 372 | |
7c2b8baa VW |
373 | /* |
374 | * For a headless page, its handle is its pointer with the extra | |
375 | * PAGE_HEADLESS bit set | |
376 | */ | |
377 | if (bud == HEADLESS) | |
378 | return h | (1 << PAGE_HEADLESS); | |
379 | ||
380 | /* otherwise, return pointer to encoded handle */ | |
381 | idx = __idx(zhdr, bud); | |
382 | h += idx; | |
383 | if (bud == LAST) | |
384 | h |= (zhdr->last_chunks << BUDDY_SHIFT); | |
385 | ||
386 | slots = zhdr->slots; | |
387 | slots->slot[idx] = h; | |
388 | return (unsigned long)&slots->slot[idx]; | |
9a001fc1 VW |
389 | } |
390 | ||
391 | /* Returns the z3fold page where a given handle is stored */ | |
1f862989 | 392 | static inline struct z3fold_header *handle_to_z3fold_header(unsigned long h) |
9a001fc1 | 393 | { |
1f862989 | 394 | unsigned long addr = h; |
7c2b8baa VW |
395 | |
396 | if (!(addr & (1 << PAGE_HEADLESS))) | |
1f862989 | 397 | addr = *(unsigned long *)h; |
7c2b8baa VW |
398 | |
399 | return (struct z3fold_header *)(addr & PAGE_MASK); | |
9a001fc1 VW |
400 | } |
401 | ||
ca0246bb VW |
402 | /* only for LAST bud, returns zero otherwise */ |
403 | static unsigned short handle_to_chunks(unsigned long handle) | |
404 | { | |
7c2b8baa VW |
405 | unsigned long addr = *(unsigned long *)handle; |
406 | ||
407 | return (addr & ~PAGE_MASK) >> BUDDY_SHIFT; | |
ca0246bb VW |
408 | } |
409 | ||
f201ebd8 | 410 | /* |
411 | * (handle & BUDDY_MASK) < zhdr->first_num is possible in encode_handle | |
412 | * but that doesn't matter. because the masking will result in the | |
413 | * correct buddy number. | |
414 | */ | |
9a001fc1 VW |
415 | static enum buddy handle_to_buddy(unsigned long handle) |
416 | { | |
7c2b8baa VW |
417 | struct z3fold_header *zhdr; |
418 | unsigned long addr; | |
419 | ||
420 | WARN_ON(handle & (1 << PAGE_HEADLESS)); | |
421 | addr = *(unsigned long *)handle; | |
422 | zhdr = (struct z3fold_header *)(addr & PAGE_MASK); | |
423 | return (addr - zhdr->first_num) & BUDDY_MASK; | |
9a001fc1 VW |
424 | } |
425 | ||
9050cce1 VW |
426 | static inline struct z3fold_pool *zhdr_to_pool(struct z3fold_header *zhdr) |
427 | { | |
7c2b8baa | 428 | return slots_to_pool(zhdr->slots); |
9050cce1 VW |
429 | } |
430 | ||
d30561c5 VW |
431 | static void __release_z3fold_page(struct z3fold_header *zhdr, bool locked) |
432 | { | |
433 | struct page *page = virt_to_page(zhdr); | |
9050cce1 | 434 | struct z3fold_pool *pool = zhdr_to_pool(zhdr); |
d30561c5 VW |
435 | |
436 | WARN_ON(!list_empty(&zhdr->buddy)); | |
437 | set_bit(PAGE_STALE, &page->private); | |
35529357 | 438 | clear_bit(NEEDS_COMPACTING, &page->private); |
d30561c5 VW |
439 | spin_lock(&pool->lock); |
440 | if (!list_empty(&page->lru)) | |
1f862989 | 441 | list_del_init(&page->lru); |
d30561c5 VW |
442 | spin_unlock(&pool->lock); |
443 | if (locked) | |
444 | z3fold_page_unlock(zhdr); | |
445 | spin_lock(&pool->stale_lock); | |
446 | list_add(&zhdr->buddy, &pool->stale); | |
447 | queue_work(pool->release_wq, &pool->work); | |
448 | spin_unlock(&pool->stale_lock); | |
449 | } | |
450 | ||
451 | static void __attribute__((__unused__)) | |
452 | release_z3fold_page(struct kref *ref) | |
453 | { | |
454 | struct z3fold_header *zhdr = container_of(ref, struct z3fold_header, | |
455 | refcount); | |
456 | __release_z3fold_page(zhdr, false); | |
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); | |
9050cce1 VW |
471 | struct z3fold_pool *pool = zhdr_to_pool(zhdr); |
472 | spin_lock(&pool->lock); | |
d30561c5 | 473 | list_del_init(&zhdr->buddy); |
9050cce1 | 474 | spin_unlock(&pool->lock); |
d30561c5 VW |
475 | |
476 | WARN_ON(z3fold_page_trylock(zhdr)); | |
477 | __release_z3fold_page(zhdr, true); | |
478 | } | |
479 | ||
480 | static void free_pages_work(struct work_struct *w) | |
481 | { | |
482 | struct z3fold_pool *pool = container_of(w, struct z3fold_pool, work); | |
483 | ||
484 | spin_lock(&pool->stale_lock); | |
485 | while (!list_empty(&pool->stale)) { | |
486 | struct z3fold_header *zhdr = list_first_entry(&pool->stale, | |
487 | struct z3fold_header, buddy); | |
488 | struct page *page = virt_to_page(zhdr); | |
489 | ||
490 | list_del(&zhdr->buddy); | |
491 | if (WARN_ON(!test_bit(PAGE_STALE, &page->private))) | |
492 | continue; | |
d30561c5 VW |
493 | spin_unlock(&pool->stale_lock); |
494 | cancel_work_sync(&zhdr->work); | |
1f862989 | 495 | free_z3fold_page(page, false); |
d30561c5 VW |
496 | cond_resched(); |
497 | spin_lock(&pool->stale_lock); | |
498 | } | |
499 | spin_unlock(&pool->stale_lock); | |
500 | } | |
501 | ||
9a001fc1 VW |
502 | /* |
503 | * Returns the number of free chunks in a z3fold page. | |
504 | * NB: can't be used with HEADLESS pages. | |
505 | */ | |
506 | static int num_free_chunks(struct z3fold_header *zhdr) | |
507 | { | |
508 | int nfree; | |
509 | /* | |
510 | * If there is a middle object, pick up the bigger free space | |
511 | * either before or after it. Otherwise just subtract the number | |
512 | * of chunks occupied by the first and the last objects. | |
513 | */ | |
514 | if (zhdr->middle_chunks != 0) { | |
515 | int nfree_before = zhdr->first_chunks ? | |
ede93213 | 516 | 0 : zhdr->start_middle - ZHDR_CHUNKS; |
9a001fc1 | 517 | int nfree_after = zhdr->last_chunks ? |
ede93213 VW |
518 | 0 : TOTAL_CHUNKS - |
519 | (zhdr->start_middle + zhdr->middle_chunks); | |
9a001fc1 VW |
520 | nfree = max(nfree_before, nfree_after); |
521 | } else | |
522 | nfree = NCHUNKS - zhdr->first_chunks - zhdr->last_chunks; | |
523 | return nfree; | |
524 | } | |
525 | ||
9050cce1 VW |
526 | /* Add to the appropriate unbuddied list */ |
527 | static inline void add_to_unbuddied(struct z3fold_pool *pool, | |
528 | struct z3fold_header *zhdr) | |
529 | { | |
530 | if (zhdr->first_chunks == 0 || zhdr->last_chunks == 0 || | |
531 | zhdr->middle_chunks == 0) { | |
532 | struct list_head *unbuddied = get_cpu_ptr(pool->unbuddied); | |
533 | ||
534 | int freechunks = num_free_chunks(zhdr); | |
535 | spin_lock(&pool->lock); | |
536 | list_add(&zhdr->buddy, &unbuddied[freechunks]); | |
537 | spin_unlock(&pool->lock); | |
538 | zhdr->cpu = smp_processor_id(); | |
539 | put_cpu_ptr(pool->unbuddied); | |
540 | } | |
541 | } | |
542 | ||
ede93213 VW |
543 | static inline void *mchunk_memmove(struct z3fold_header *zhdr, |
544 | unsigned short dst_chunk) | |
545 | { | |
546 | void *beg = zhdr; | |
547 | return memmove(beg + (dst_chunk << CHUNK_SHIFT), | |
548 | beg + (zhdr->start_middle << CHUNK_SHIFT), | |
549 | zhdr->middle_chunks << CHUNK_SHIFT); | |
550 | } | |
551 | ||
1b096e5a | 552 | #define BIG_CHUNK_GAP 3 |
9a001fc1 VW |
553 | /* Has to be called with lock held */ |
554 | static int z3fold_compact_page(struct z3fold_header *zhdr) | |
555 | { | |
556 | struct page *page = virt_to_page(zhdr); | |
9a001fc1 | 557 | |
ede93213 VW |
558 | if (test_bit(MIDDLE_CHUNK_MAPPED, &page->private)) |
559 | return 0; /* can't move middle chunk, it's used */ | |
9a001fc1 | 560 | |
1f862989 VW |
561 | if (unlikely(PageIsolated(page))) |
562 | return 0; | |
563 | ||
ede93213 VW |
564 | if (zhdr->middle_chunks == 0) |
565 | return 0; /* nothing to compact */ | |
566 | ||
567 | if (zhdr->first_chunks == 0 && zhdr->last_chunks == 0) { | |
568 | /* move to the beginning */ | |
569 | mchunk_memmove(zhdr, ZHDR_CHUNKS); | |
9a001fc1 VW |
570 | zhdr->first_chunks = zhdr->middle_chunks; |
571 | zhdr->middle_chunks = 0; | |
572 | zhdr->start_middle = 0; | |
573 | zhdr->first_num++; | |
1b096e5a | 574 | return 1; |
9a001fc1 | 575 | } |
1b096e5a VW |
576 | |
577 | /* | |
578 | * moving data is expensive, so let's only do that if | |
579 | * there's substantial gain (at least BIG_CHUNK_GAP chunks) | |
580 | */ | |
581 | if (zhdr->first_chunks != 0 && zhdr->last_chunks == 0 && | |
582 | zhdr->start_middle - (zhdr->first_chunks + ZHDR_CHUNKS) >= | |
583 | BIG_CHUNK_GAP) { | |
584 | mchunk_memmove(zhdr, zhdr->first_chunks + ZHDR_CHUNKS); | |
585 | zhdr->start_middle = zhdr->first_chunks + ZHDR_CHUNKS; | |
586 | return 1; | |
587 | } else if (zhdr->last_chunks != 0 && zhdr->first_chunks == 0 && | |
588 | TOTAL_CHUNKS - (zhdr->last_chunks + zhdr->start_middle | |
589 | + zhdr->middle_chunks) >= | |
590 | BIG_CHUNK_GAP) { | |
591 | unsigned short new_start = TOTAL_CHUNKS - zhdr->last_chunks - | |
592 | zhdr->middle_chunks; | |
593 | mchunk_memmove(zhdr, new_start); | |
594 | zhdr->start_middle = new_start; | |
595 | return 1; | |
596 | } | |
597 | ||
598 | return 0; | |
9a001fc1 VW |
599 | } |
600 | ||
d30561c5 VW |
601 | static void do_compact_page(struct z3fold_header *zhdr, bool locked) |
602 | { | |
9050cce1 | 603 | struct z3fold_pool *pool = zhdr_to_pool(zhdr); |
d30561c5 | 604 | struct page *page; |
d30561c5 VW |
605 | |
606 | page = virt_to_page(zhdr); | |
607 | if (locked) | |
608 | WARN_ON(z3fold_page_trylock(zhdr)); | |
609 | else | |
610 | z3fold_page_lock(zhdr); | |
5d03a661 | 611 | if (WARN_ON(!test_and_clear_bit(NEEDS_COMPACTING, &page->private))) { |
d30561c5 VW |
612 | z3fold_page_unlock(zhdr); |
613 | return; | |
614 | } | |
615 | spin_lock(&pool->lock); | |
616 | list_del_init(&zhdr->buddy); | |
617 | spin_unlock(&pool->lock); | |
618 | ||
5d03a661 VW |
619 | if (kref_put(&zhdr->refcount, release_z3fold_page_locked)) { |
620 | atomic64_dec(&pool->pages_nr); | |
621 | return; | |
622 | } | |
623 | ||
1f862989 VW |
624 | if (unlikely(PageIsolated(page) || |
625 | test_bit(PAGE_STALE, &page->private))) { | |
626 | z3fold_page_unlock(zhdr); | |
627 | return; | |
628 | } | |
629 | ||
d30561c5 | 630 | z3fold_compact_page(zhdr); |
9050cce1 | 631 | add_to_unbuddied(pool, zhdr); |
d30561c5 VW |
632 | z3fold_page_unlock(zhdr); |
633 | } | |
634 | ||
635 | static void compact_page_work(struct work_struct *w) | |
636 | { | |
637 | struct z3fold_header *zhdr = container_of(w, struct z3fold_header, | |
638 | work); | |
639 | ||
640 | do_compact_page(zhdr, false); | |
641 | } | |
642 | ||
9050cce1 VW |
643 | /* returns _locked_ z3fold page header or NULL */ |
644 | static inline struct z3fold_header *__z3fold_alloc(struct z3fold_pool *pool, | |
645 | size_t size, bool can_sleep) | |
646 | { | |
647 | struct z3fold_header *zhdr = NULL; | |
648 | struct page *page; | |
649 | struct list_head *unbuddied; | |
650 | int chunks = size_to_chunks(size), i; | |
651 | ||
652 | lookup: | |
653 | /* First, try to find an unbuddied z3fold page. */ | |
654 | unbuddied = get_cpu_ptr(pool->unbuddied); | |
655 | for_each_unbuddied_list(i, chunks) { | |
656 | struct list_head *l = &unbuddied[i]; | |
657 | ||
658 | zhdr = list_first_entry_or_null(READ_ONCE(l), | |
659 | struct z3fold_header, buddy); | |
660 | ||
661 | if (!zhdr) | |
662 | continue; | |
663 | ||
664 | /* Re-check under lock. */ | |
665 | spin_lock(&pool->lock); | |
666 | l = &unbuddied[i]; | |
667 | if (unlikely(zhdr != list_first_entry(READ_ONCE(l), | |
668 | struct z3fold_header, buddy)) || | |
669 | !z3fold_page_trylock(zhdr)) { | |
670 | spin_unlock(&pool->lock); | |
671 | zhdr = NULL; | |
672 | put_cpu_ptr(pool->unbuddied); | |
673 | if (can_sleep) | |
674 | cond_resched(); | |
675 | goto lookup; | |
676 | } | |
677 | list_del_init(&zhdr->buddy); | |
678 | zhdr->cpu = -1; | |
679 | spin_unlock(&pool->lock); | |
680 | ||
681 | page = virt_to_page(zhdr); | |
682 | if (test_bit(NEEDS_COMPACTING, &page->private)) { | |
683 | z3fold_page_unlock(zhdr); | |
684 | zhdr = NULL; | |
685 | put_cpu_ptr(pool->unbuddied); | |
686 | if (can_sleep) | |
687 | cond_resched(); | |
688 | goto lookup; | |
689 | } | |
690 | ||
691 | /* | |
692 | * this page could not be removed from its unbuddied | |
693 | * list while pool lock was held, and then we've taken | |
694 | * page lock so kref_put could not be called before | |
695 | * we got here, so it's safe to just call kref_get() | |
696 | */ | |
697 | kref_get(&zhdr->refcount); | |
698 | break; | |
699 | } | |
700 | put_cpu_ptr(pool->unbuddied); | |
701 | ||
351618b2 VW |
702 | if (!zhdr) { |
703 | int cpu; | |
704 | ||
705 | /* look for _exact_ match on other cpus' lists */ | |
706 | for_each_online_cpu(cpu) { | |
707 | struct list_head *l; | |
708 | ||
709 | unbuddied = per_cpu_ptr(pool->unbuddied, cpu); | |
710 | spin_lock(&pool->lock); | |
711 | l = &unbuddied[chunks]; | |
712 | ||
713 | zhdr = list_first_entry_or_null(READ_ONCE(l), | |
714 | struct z3fold_header, buddy); | |
715 | ||
716 | if (!zhdr || !z3fold_page_trylock(zhdr)) { | |
717 | spin_unlock(&pool->lock); | |
718 | zhdr = NULL; | |
719 | continue; | |
720 | } | |
721 | list_del_init(&zhdr->buddy); | |
722 | zhdr->cpu = -1; | |
723 | spin_unlock(&pool->lock); | |
724 | ||
725 | page = virt_to_page(zhdr); | |
726 | if (test_bit(NEEDS_COMPACTING, &page->private)) { | |
727 | z3fold_page_unlock(zhdr); | |
728 | zhdr = NULL; | |
729 | if (can_sleep) | |
730 | cond_resched(); | |
731 | continue; | |
732 | } | |
733 | kref_get(&zhdr->refcount); | |
734 | break; | |
735 | } | |
736 | } | |
737 | ||
9050cce1 VW |
738 | return zhdr; |
739 | } | |
d30561c5 VW |
740 | |
741 | /* | |
742 | * API Functions | |
743 | */ | |
744 | ||
745 | /** | |
746 | * z3fold_create_pool() - create a new z3fold pool | |
747 | * @name: pool name | |
748 | * @gfp: gfp flags when allocating the z3fold pool structure | |
749 | * @ops: user-defined operations for the z3fold pool | |
750 | * | |
751 | * Return: pointer to the new z3fold pool or NULL if the metadata allocation | |
752 | * failed. | |
753 | */ | |
754 | static struct z3fold_pool *z3fold_create_pool(const char *name, gfp_t gfp, | |
755 | const struct z3fold_ops *ops) | |
756 | { | |
757 | struct z3fold_pool *pool = NULL; | |
758 | int i, cpu; | |
759 | ||
760 | pool = kzalloc(sizeof(struct z3fold_pool), gfp); | |
761 | if (!pool) | |
762 | goto out; | |
7c2b8baa VW |
763 | pool->c_handle = kmem_cache_create("z3fold_handle", |
764 | sizeof(struct z3fold_buddy_slots), | |
765 | SLOTS_ALIGN, 0, NULL); | |
766 | if (!pool->c_handle) | |
767 | goto out_c; | |
d30561c5 VW |
768 | spin_lock_init(&pool->lock); |
769 | spin_lock_init(&pool->stale_lock); | |
770 | pool->unbuddied = __alloc_percpu(sizeof(struct list_head)*NCHUNKS, 2); | |
1ec6995d XW |
771 | if (!pool->unbuddied) |
772 | goto out_pool; | |
d30561c5 VW |
773 | for_each_possible_cpu(cpu) { |
774 | struct list_head *unbuddied = | |
775 | per_cpu_ptr(pool->unbuddied, cpu); | |
776 | for_each_unbuddied_list(i, 0) | |
777 | INIT_LIST_HEAD(&unbuddied[i]); | |
778 | } | |
779 | INIT_LIST_HEAD(&pool->lru); | |
780 | INIT_LIST_HEAD(&pool->stale); | |
781 | atomic64_set(&pool->pages_nr, 0); | |
782 | pool->name = name; | |
783 | pool->compact_wq = create_singlethread_workqueue(pool->name); | |
784 | if (!pool->compact_wq) | |
1ec6995d | 785 | goto out_unbuddied; |
d30561c5 VW |
786 | pool->release_wq = create_singlethread_workqueue(pool->name); |
787 | if (!pool->release_wq) | |
788 | goto out_wq; | |
1f862989 VW |
789 | if (z3fold_register_migration(pool)) |
790 | goto out_rwq; | |
d30561c5 VW |
791 | INIT_WORK(&pool->work, free_pages_work); |
792 | pool->ops = ops; | |
793 | return pool; | |
794 | ||
1f862989 VW |
795 | out_rwq: |
796 | destroy_workqueue(pool->release_wq); | |
d30561c5 VW |
797 | out_wq: |
798 | destroy_workqueue(pool->compact_wq); | |
1ec6995d XW |
799 | out_unbuddied: |
800 | free_percpu(pool->unbuddied); | |
801 | out_pool: | |
7c2b8baa VW |
802 | kmem_cache_destroy(pool->c_handle); |
803 | out_c: | |
d30561c5 | 804 | kfree(pool); |
1ec6995d | 805 | out: |
d30561c5 VW |
806 | return NULL; |
807 | } | |
808 | ||
809 | /** | |
810 | * z3fold_destroy_pool() - destroys an existing z3fold pool | |
811 | * @pool: the z3fold pool to be destroyed | |
812 | * | |
813 | * The pool should be emptied before this function is called. | |
814 | */ | |
815 | static void z3fold_destroy_pool(struct z3fold_pool *pool) | |
816 | { | |
7c2b8baa | 817 | kmem_cache_destroy(pool->c_handle); |
1f862989 | 818 | z3fold_unregister_migration(pool); |
d30561c5 VW |
819 | destroy_workqueue(pool->release_wq); |
820 | destroy_workqueue(pool->compact_wq); | |
821 | kfree(pool); | |
822 | } | |
823 | ||
9a001fc1 VW |
824 | /** |
825 | * z3fold_alloc() - allocates a region of a given size | |
826 | * @pool: z3fold pool from which to allocate | |
827 | * @size: size in bytes of the desired allocation | |
828 | * @gfp: gfp flags used if the pool needs to grow | |
829 | * @handle: handle of the new allocation | |
830 | * | |
831 | * This function will attempt to find a free region in the pool large enough to | |
832 | * satisfy the allocation request. A search of the unbuddied lists is | |
833 | * performed first. If no suitable free region is found, then a new page is | |
834 | * allocated and added to the pool to satisfy the request. | |
835 | * | |
836 | * gfp should not set __GFP_HIGHMEM as highmem pages cannot be used | |
837 | * as z3fold pool pages. | |
838 | * | |
839 | * Return: 0 if success and handle is set, otherwise -EINVAL if the size or | |
840 | * gfp arguments are invalid or -ENOMEM if the pool was unable to allocate | |
841 | * a new page. | |
842 | */ | |
843 | static int z3fold_alloc(struct z3fold_pool *pool, size_t size, gfp_t gfp, | |
844 | unsigned long *handle) | |
845 | { | |
9050cce1 | 846 | int chunks = size_to_chunks(size); |
9a001fc1 | 847 | struct z3fold_header *zhdr = NULL; |
d30561c5 | 848 | struct page *page = NULL; |
9a001fc1 | 849 | enum buddy bud; |
8a97ea54 | 850 | bool can_sleep = gfpflags_allow_blocking(gfp); |
9a001fc1 VW |
851 | |
852 | if (!size || (gfp & __GFP_HIGHMEM)) | |
853 | return -EINVAL; | |
854 | ||
855 | if (size > PAGE_SIZE) | |
856 | return -ENOSPC; | |
857 | ||
858 | if (size > PAGE_SIZE - ZHDR_SIZE_ALIGNED - CHUNK_SIZE) | |
859 | bud = HEADLESS; | |
860 | else { | |
9050cce1 VW |
861 | retry: |
862 | zhdr = __z3fold_alloc(pool, size, can_sleep); | |
d30561c5 | 863 | if (zhdr) { |
2f1e5e4d VW |
864 | if (zhdr->first_chunks == 0) { |
865 | if (zhdr->middle_chunks != 0 && | |
866 | chunks >= zhdr->start_middle) | |
9a001fc1 | 867 | bud = LAST; |
2f1e5e4d VW |
868 | else |
869 | bud = FIRST; | |
870 | } else if (zhdr->last_chunks == 0) | |
871 | bud = LAST; | |
872 | else if (zhdr->middle_chunks == 0) | |
873 | bud = MIDDLE; | |
874 | else { | |
5a27aa82 | 875 | if (kref_put(&zhdr->refcount, |
d30561c5 | 876 | release_z3fold_page_locked)) |
5a27aa82 | 877 | atomic64_dec(&pool->pages_nr); |
d30561c5 VW |
878 | else |
879 | z3fold_page_unlock(zhdr); | |
2f1e5e4d VW |
880 | pr_err("No free chunks in unbuddied\n"); |
881 | WARN_ON(1); | |
9050cce1 | 882 | goto retry; |
9a001fc1 | 883 | } |
9050cce1 | 884 | page = virt_to_page(zhdr); |
2f1e5e4d | 885 | goto found; |
9a001fc1 VW |
886 | } |
887 | bud = FIRST; | |
9a001fc1 VW |
888 | } |
889 | ||
5c9bab59 VW |
890 | page = NULL; |
891 | if (can_sleep) { | |
892 | spin_lock(&pool->stale_lock); | |
893 | zhdr = list_first_entry_or_null(&pool->stale, | |
894 | struct z3fold_header, buddy); | |
895 | /* | |
896 | * Before allocating a page, let's see if we can take one from | |
897 | * the stale pages list. cancel_work_sync() can sleep so we | |
898 | * limit this case to the contexts where we can sleep | |
899 | */ | |
900 | if (zhdr) { | |
901 | list_del(&zhdr->buddy); | |
902 | spin_unlock(&pool->stale_lock); | |
d30561c5 | 903 | cancel_work_sync(&zhdr->work); |
5c9bab59 VW |
904 | page = virt_to_page(zhdr); |
905 | } else { | |
906 | spin_unlock(&pool->stale_lock); | |
907 | } | |
d30561c5 | 908 | } |
5c9bab59 VW |
909 | if (!page) |
910 | page = alloc_page(gfp); | |
d30561c5 | 911 | |
9a001fc1 VW |
912 | if (!page) |
913 | return -ENOMEM; | |
2f1e5e4d | 914 | |
d30561c5 | 915 | zhdr = init_z3fold_page(page, pool); |
9050cce1 VW |
916 | if (!zhdr) { |
917 | __free_page(page); | |
918 | return -ENOMEM; | |
919 | } | |
920 | atomic64_inc(&pool->pages_nr); | |
9a001fc1 VW |
921 | |
922 | if (bud == HEADLESS) { | |
923 | set_bit(PAGE_HEADLESS, &page->private); | |
924 | goto headless; | |
925 | } | |
1f862989 | 926 | __SetPageMovable(page, pool->inode->i_mapping); |
2f1e5e4d | 927 | z3fold_page_lock(zhdr); |
9a001fc1 VW |
928 | |
929 | found: | |
930 | if (bud == FIRST) | |
931 | zhdr->first_chunks = chunks; | |
932 | else if (bud == LAST) | |
933 | zhdr->last_chunks = chunks; | |
934 | else { | |
935 | zhdr->middle_chunks = chunks; | |
ede93213 | 936 | zhdr->start_middle = zhdr->first_chunks + ZHDR_CHUNKS; |
9a001fc1 | 937 | } |
9050cce1 | 938 | add_to_unbuddied(pool, zhdr); |
9a001fc1 VW |
939 | |
940 | headless: | |
d30561c5 | 941 | spin_lock(&pool->lock); |
9a001fc1 VW |
942 | /* Add/move z3fold page to beginning of LRU */ |
943 | if (!list_empty(&page->lru)) | |
944 | list_del(&page->lru); | |
945 | ||
946 | list_add(&page->lru, &pool->lru); | |
947 | ||
948 | *handle = encode_handle(zhdr, bud); | |
949 | spin_unlock(&pool->lock); | |
2f1e5e4d VW |
950 | if (bud != HEADLESS) |
951 | z3fold_page_unlock(zhdr); | |
9a001fc1 VW |
952 | |
953 | return 0; | |
954 | } | |
955 | ||
956 | /** | |
957 | * z3fold_free() - frees the allocation associated with the given handle | |
958 | * @pool: pool in which the allocation resided | |
959 | * @handle: handle associated with the allocation returned by z3fold_alloc() | |
960 | * | |
961 | * In the case that the z3fold page in which the allocation resides is under | |
962 | * reclaim, as indicated by the PG_reclaim flag being set, this function | |
963 | * only sets the first|last_chunks to 0. The page is actually freed | |
964 | * once both buddies are evicted (see z3fold_reclaim_page() below). | |
965 | */ | |
966 | static void z3fold_free(struct z3fold_pool *pool, unsigned long handle) | |
967 | { | |
968 | struct z3fold_header *zhdr; | |
9a001fc1 VW |
969 | struct page *page; |
970 | enum buddy bud; | |
971 | ||
9a001fc1 VW |
972 | zhdr = handle_to_z3fold_header(handle); |
973 | page = virt_to_page(zhdr); | |
974 | ||
975 | if (test_bit(PAGE_HEADLESS, &page->private)) { | |
ca0246bb VW |
976 | /* if a headless page is under reclaim, just leave. |
977 | * NB: we use test_and_set_bit for a reason: if the bit | |
978 | * has not been set before, we release this page | |
979 | * immediately so we don't care about its value any more. | |
980 | */ | |
981 | if (!test_and_set_bit(PAGE_CLAIMED, &page->private)) { | |
982 | spin_lock(&pool->lock); | |
983 | list_del(&page->lru); | |
984 | spin_unlock(&pool->lock); | |
1f862989 | 985 | free_z3fold_page(page, true); |
ca0246bb | 986 | atomic64_dec(&pool->pages_nr); |
9a001fc1 | 987 | } |
ca0246bb | 988 | return; |
9a001fc1 VW |
989 | } |
990 | ||
ca0246bb VW |
991 | /* Non-headless case */ |
992 | z3fold_page_lock(zhdr); | |
993 | bud = handle_to_buddy(handle); | |
994 | ||
995 | switch (bud) { | |
996 | case FIRST: | |
997 | zhdr->first_chunks = 0; | |
998 | break; | |
999 | case MIDDLE: | |
1000 | zhdr->middle_chunks = 0; | |
1001 | break; | |
1002 | case LAST: | |
1003 | zhdr->last_chunks = 0; | |
1004 | break; | |
1005 | default: | |
1006 | pr_err("%s: unknown bud %d\n", __func__, bud); | |
1007 | WARN_ON(1); | |
1008 | z3fold_page_unlock(zhdr); | |
d30561c5 VW |
1009 | return; |
1010 | } | |
1011 | ||
7c2b8baa | 1012 | free_handle(handle); |
d30561c5 VW |
1013 | if (kref_put(&zhdr->refcount, release_z3fold_page_locked_list)) { |
1014 | atomic64_dec(&pool->pages_nr); | |
1015 | return; | |
1016 | } | |
ca0246bb | 1017 | if (test_bit(PAGE_CLAIMED, &page->private)) { |
6098d7e1 VW |
1018 | z3fold_page_unlock(zhdr); |
1019 | return; | |
1020 | } | |
1f862989 VW |
1021 | if (unlikely(PageIsolated(page)) || |
1022 | test_and_set_bit(NEEDS_COMPACTING, &page->private)) { | |
5a27aa82 | 1023 | z3fold_page_unlock(zhdr); |
d30561c5 VW |
1024 | return; |
1025 | } | |
1026 | if (zhdr->cpu < 0 || !cpu_online(zhdr->cpu)) { | |
2f1e5e4d | 1027 | spin_lock(&pool->lock); |
d30561c5 | 1028 | list_del_init(&zhdr->buddy); |
2f1e5e4d | 1029 | spin_unlock(&pool->lock); |
d30561c5 | 1030 | zhdr->cpu = -1; |
5d03a661 | 1031 | kref_get(&zhdr->refcount); |
d30561c5 VW |
1032 | do_compact_page(zhdr, true); |
1033 | return; | |
9a001fc1 | 1034 | } |
5d03a661 | 1035 | kref_get(&zhdr->refcount); |
d30561c5 VW |
1036 | queue_work_on(zhdr->cpu, pool->compact_wq, &zhdr->work); |
1037 | z3fold_page_unlock(zhdr); | |
9a001fc1 VW |
1038 | } |
1039 | ||
1040 | /** | |
1041 | * z3fold_reclaim_page() - evicts allocations from a pool page and frees it | |
1042 | * @pool: pool from which a page will attempt to be evicted | |
f144c390 | 1043 | * @retries: number of pages on the LRU list for which eviction will |
9a001fc1 VW |
1044 | * be attempted before failing |
1045 | * | |
1046 | * z3fold reclaim is different from normal system reclaim in that it is done | |
1047 | * from the bottom, up. This is because only the bottom layer, z3fold, has | |
1048 | * information on how the allocations are organized within each z3fold page. | |
1049 | * This has the potential to create interesting locking situations between | |
1050 | * z3fold and the user, however. | |
1051 | * | |
1052 | * To avoid these, this is how z3fold_reclaim_page() should be called: | |
f144c390 | 1053 | * |
9a001fc1 VW |
1054 | * The user detects a page should be reclaimed and calls z3fold_reclaim_page(). |
1055 | * z3fold_reclaim_page() will remove a z3fold page from the pool LRU list and | |
1056 | * call the user-defined eviction handler with the pool and handle as | |
1057 | * arguments. | |
1058 | * | |
1059 | * If the handle can not be evicted, the eviction handler should return | |
1060 | * non-zero. z3fold_reclaim_page() will add the z3fold page back to the | |
1061 | * appropriate list and try the next z3fold page on the LRU up to | |
1062 | * a user defined number of retries. | |
1063 | * | |
1064 | * If the handle is successfully evicted, the eviction handler should | |
1065 | * return 0 _and_ should have called z3fold_free() on the handle. z3fold_free() | |
1066 | * contains logic to delay freeing the page if the page is under reclaim, | |
1067 | * as indicated by the setting of the PG_reclaim flag on the underlying page. | |
1068 | * | |
1069 | * If all buddies in the z3fold page are successfully evicted, then the | |
1070 | * z3fold page can be freed. | |
1071 | * | |
1072 | * Returns: 0 if page is successfully freed, otherwise -EINVAL if there are | |
1073 | * no pages to evict or an eviction handler is not registered, -EAGAIN if | |
1074 | * the retry limit was hit. | |
1075 | */ | |
1076 | static int z3fold_reclaim_page(struct z3fold_pool *pool, unsigned int retries) | |
1077 | { | |
d30561c5 VW |
1078 | int i, ret = 0; |
1079 | struct z3fold_header *zhdr = NULL; | |
1080 | struct page *page = NULL; | |
1081 | struct list_head *pos; | |
9a001fc1 VW |
1082 | unsigned long first_handle = 0, middle_handle = 0, last_handle = 0; |
1083 | ||
1084 | spin_lock(&pool->lock); | |
2f1e5e4d | 1085 | if (!pool->ops || !pool->ops->evict || retries == 0) { |
9a001fc1 VW |
1086 | spin_unlock(&pool->lock); |
1087 | return -EINVAL; | |
1088 | } | |
1089 | for (i = 0; i < retries; i++) { | |
2f1e5e4d VW |
1090 | if (list_empty(&pool->lru)) { |
1091 | spin_unlock(&pool->lock); | |
1092 | return -EINVAL; | |
1093 | } | |
d30561c5 VW |
1094 | list_for_each_prev(pos, &pool->lru) { |
1095 | page = list_entry(pos, struct page, lru); | |
ca0246bb VW |
1096 | |
1097 | /* this bit could have been set by free, in which case | |
1098 | * we pass over to the next page in the pool. | |
1099 | */ | |
1100 | if (test_and_set_bit(PAGE_CLAIMED, &page->private)) | |
1101 | continue; | |
1102 | ||
1f862989 VW |
1103 | if (unlikely(PageIsolated(page))) |
1104 | continue; | |
d30561c5 | 1105 | if (test_bit(PAGE_HEADLESS, &page->private)) |
d30561c5 VW |
1106 | break; |
1107 | ||
1f862989 | 1108 | zhdr = page_address(page); |
ca0246bb VW |
1109 | if (!z3fold_page_trylock(zhdr)) { |
1110 | zhdr = NULL; | |
d30561c5 | 1111 | continue; /* can't evict at this point */ |
ca0246bb | 1112 | } |
d30561c5 VW |
1113 | kref_get(&zhdr->refcount); |
1114 | list_del_init(&zhdr->buddy); | |
1115 | zhdr->cpu = -1; | |
6098d7e1 | 1116 | break; |
d30561c5 VW |
1117 | } |
1118 | ||
ca0246bb VW |
1119 | if (!zhdr) |
1120 | break; | |
1121 | ||
5a27aa82 | 1122 | list_del_init(&page->lru); |
d30561c5 | 1123 | spin_unlock(&pool->lock); |
9a001fc1 | 1124 | |
9a001fc1 | 1125 | if (!test_bit(PAGE_HEADLESS, &page->private)) { |
9a001fc1 VW |
1126 | /* |
1127 | * We need encode the handles before unlocking, since | |
1128 | * we can race with free that will set | |
1129 | * (first|last)_chunks to 0 | |
1130 | */ | |
1131 | first_handle = 0; | |
1132 | last_handle = 0; | |
1133 | middle_handle = 0; | |
1134 | if (zhdr->first_chunks) | |
1135 | first_handle = encode_handle(zhdr, FIRST); | |
1136 | if (zhdr->middle_chunks) | |
1137 | middle_handle = encode_handle(zhdr, MIDDLE); | |
1138 | if (zhdr->last_chunks) | |
1139 | last_handle = encode_handle(zhdr, LAST); | |
d30561c5 VW |
1140 | /* |
1141 | * it's safe to unlock here because we hold a | |
1142 | * reference to this page | |
1143 | */ | |
2f1e5e4d | 1144 | z3fold_page_unlock(zhdr); |
9a001fc1 VW |
1145 | } else { |
1146 | first_handle = encode_handle(zhdr, HEADLESS); | |
1147 | last_handle = middle_handle = 0; | |
1148 | } | |
1149 | ||
9a001fc1 VW |
1150 | /* Issue the eviction callback(s) */ |
1151 | if (middle_handle) { | |
1152 | ret = pool->ops->evict(pool, middle_handle); | |
1153 | if (ret) | |
1154 | goto next; | |
1155 | } | |
1156 | if (first_handle) { | |
1157 | ret = pool->ops->evict(pool, first_handle); | |
1158 | if (ret) | |
1159 | goto next; | |
1160 | } | |
1161 | if (last_handle) { | |
1162 | ret = pool->ops->evict(pool, last_handle); | |
1163 | if (ret) | |
1164 | goto next; | |
1165 | } | |
1166 | next: | |
5a27aa82 VW |
1167 | if (test_bit(PAGE_HEADLESS, &page->private)) { |
1168 | if (ret == 0) { | |
1f862989 | 1169 | free_z3fold_page(page, true); |
ca0246bb | 1170 | atomic64_dec(&pool->pages_nr); |
5a27aa82 | 1171 | return 0; |
5a27aa82 | 1172 | } |
6098d7e1 VW |
1173 | spin_lock(&pool->lock); |
1174 | list_add(&page->lru, &pool->lru); | |
1175 | spin_unlock(&pool->lock); | |
1176 | } else { | |
1177 | z3fold_page_lock(zhdr); | |
ca0246bb | 1178 | clear_bit(PAGE_CLAIMED, &page->private); |
6098d7e1 VW |
1179 | if (kref_put(&zhdr->refcount, |
1180 | release_z3fold_page_locked)) { | |
1181 | atomic64_dec(&pool->pages_nr); | |
1182 | return 0; | |
1183 | } | |
1184 | /* | |
1185 | * if we are here, the page is still not completely | |
1186 | * free. Take the global pool lock then to be able | |
1187 | * to add it back to the lru list | |
1188 | */ | |
1189 | spin_lock(&pool->lock); | |
1190 | list_add(&page->lru, &pool->lru); | |
d5567c9d | 1191 | spin_unlock(&pool->lock); |
6098d7e1 | 1192 | z3fold_page_unlock(zhdr); |
5a27aa82 | 1193 | } |
2f1e5e4d | 1194 | |
6098d7e1 VW |
1195 | /* We started off locked to we need to lock the pool back */ |
1196 | spin_lock(&pool->lock); | |
9a001fc1 VW |
1197 | } |
1198 | spin_unlock(&pool->lock); | |
1199 | return -EAGAIN; | |
1200 | } | |
1201 | ||
1202 | /** | |
1203 | * z3fold_map() - maps the allocation associated with the given handle | |
1204 | * @pool: pool in which the allocation resides | |
1205 | * @handle: handle associated with the allocation to be mapped | |
1206 | * | |
1207 | * Extracts the buddy number from handle and constructs the pointer to the | |
1208 | * correct starting chunk within the page. | |
1209 | * | |
1210 | * Returns: a pointer to the mapped allocation | |
1211 | */ | |
1212 | static void *z3fold_map(struct z3fold_pool *pool, unsigned long handle) | |
1213 | { | |
1214 | struct z3fold_header *zhdr; | |
1215 | struct page *page; | |
1216 | void *addr; | |
1217 | enum buddy buddy; | |
1218 | ||
9a001fc1 VW |
1219 | zhdr = handle_to_z3fold_header(handle); |
1220 | addr = zhdr; | |
1221 | page = virt_to_page(zhdr); | |
1222 | ||
1223 | if (test_bit(PAGE_HEADLESS, &page->private)) | |
1224 | goto out; | |
1225 | ||
2f1e5e4d | 1226 | z3fold_page_lock(zhdr); |
9a001fc1 VW |
1227 | buddy = handle_to_buddy(handle); |
1228 | switch (buddy) { | |
1229 | case FIRST: | |
1230 | addr += ZHDR_SIZE_ALIGNED; | |
1231 | break; | |
1232 | case MIDDLE: | |
1233 | addr += zhdr->start_middle << CHUNK_SHIFT; | |
1234 | set_bit(MIDDLE_CHUNK_MAPPED, &page->private); | |
1235 | break; | |
1236 | case LAST: | |
ca0246bb | 1237 | addr += PAGE_SIZE - (handle_to_chunks(handle) << CHUNK_SHIFT); |
9a001fc1 VW |
1238 | break; |
1239 | default: | |
1240 | pr_err("unknown buddy id %d\n", buddy); | |
1241 | WARN_ON(1); | |
1242 | addr = NULL; | |
1243 | break; | |
1244 | } | |
2f1e5e4d | 1245 | |
1f862989 VW |
1246 | if (addr) |
1247 | zhdr->mapped_count++; | |
2f1e5e4d | 1248 | z3fold_page_unlock(zhdr); |
9a001fc1 | 1249 | out: |
9a001fc1 VW |
1250 | return addr; |
1251 | } | |
1252 | ||
1253 | /** | |
1254 | * z3fold_unmap() - unmaps the allocation associated with the given handle | |
1255 | * @pool: pool in which the allocation resides | |
1256 | * @handle: handle associated with the allocation to be unmapped | |
1257 | */ | |
1258 | static void z3fold_unmap(struct z3fold_pool *pool, unsigned long handle) | |
1259 | { | |
1260 | struct z3fold_header *zhdr; | |
1261 | struct page *page; | |
1262 | enum buddy buddy; | |
1263 | ||
9a001fc1 VW |
1264 | zhdr = handle_to_z3fold_header(handle); |
1265 | page = virt_to_page(zhdr); | |
1266 | ||
2f1e5e4d | 1267 | if (test_bit(PAGE_HEADLESS, &page->private)) |
9a001fc1 | 1268 | return; |
9a001fc1 | 1269 | |
2f1e5e4d | 1270 | z3fold_page_lock(zhdr); |
9a001fc1 VW |
1271 | buddy = handle_to_buddy(handle); |
1272 | if (buddy == MIDDLE) | |
1273 | clear_bit(MIDDLE_CHUNK_MAPPED, &page->private); | |
1f862989 | 1274 | zhdr->mapped_count--; |
2f1e5e4d | 1275 | z3fold_page_unlock(zhdr); |
9a001fc1 VW |
1276 | } |
1277 | ||
1278 | /** | |
1279 | * z3fold_get_pool_size() - gets the z3fold pool size in pages | |
1280 | * @pool: pool whose size is being queried | |
1281 | * | |
12d59ae6 | 1282 | * Returns: size in pages of the given pool. |
9a001fc1 VW |
1283 | */ |
1284 | static u64 z3fold_get_pool_size(struct z3fold_pool *pool) | |
1285 | { | |
12d59ae6 | 1286 | return atomic64_read(&pool->pages_nr); |
9a001fc1 VW |
1287 | } |
1288 | ||
1f862989 VW |
1289 | static bool z3fold_page_isolate(struct page *page, isolate_mode_t mode) |
1290 | { | |
1291 | struct z3fold_header *zhdr; | |
1292 | struct z3fold_pool *pool; | |
1293 | ||
1294 | VM_BUG_ON_PAGE(!PageMovable(page), page); | |
1295 | VM_BUG_ON_PAGE(PageIsolated(page), page); | |
1296 | ||
1297 | if (test_bit(PAGE_HEADLESS, &page->private)) | |
1298 | return false; | |
1299 | ||
1300 | zhdr = page_address(page); | |
1301 | z3fold_page_lock(zhdr); | |
1302 | if (test_bit(NEEDS_COMPACTING, &page->private) || | |
1303 | test_bit(PAGE_STALE, &page->private)) | |
1304 | goto out; | |
1305 | ||
1306 | pool = zhdr_to_pool(zhdr); | |
1307 | ||
1308 | if (zhdr->mapped_count == 0) { | |
1309 | kref_get(&zhdr->refcount); | |
1310 | if (!list_empty(&zhdr->buddy)) | |
1311 | list_del_init(&zhdr->buddy); | |
1312 | spin_lock(&pool->lock); | |
1313 | if (!list_empty(&page->lru)) | |
1314 | list_del(&page->lru); | |
1315 | spin_unlock(&pool->lock); | |
1316 | z3fold_page_unlock(zhdr); | |
1317 | return true; | |
1318 | } | |
1319 | out: | |
1320 | z3fold_page_unlock(zhdr); | |
1321 | return false; | |
1322 | } | |
1323 | ||
1324 | static int z3fold_page_migrate(struct address_space *mapping, struct page *newpage, | |
1325 | struct page *page, enum migrate_mode mode) | |
1326 | { | |
1327 | struct z3fold_header *zhdr, *new_zhdr; | |
1328 | struct z3fold_pool *pool; | |
1329 | struct address_space *new_mapping; | |
1330 | ||
1331 | VM_BUG_ON_PAGE(!PageMovable(page), page); | |
1332 | VM_BUG_ON_PAGE(!PageIsolated(page), page); | |
1333 | ||
1334 | zhdr = page_address(page); | |
1335 | pool = zhdr_to_pool(zhdr); | |
1336 | ||
1337 | if (!trylock_page(page)) | |
1338 | return -EAGAIN; | |
1339 | ||
1340 | if (!z3fold_page_trylock(zhdr)) { | |
1341 | unlock_page(page); | |
1342 | return -EAGAIN; | |
1343 | } | |
1344 | if (zhdr->mapped_count != 0) { | |
1345 | z3fold_page_unlock(zhdr); | |
1346 | unlock_page(page); | |
1347 | return -EBUSY; | |
1348 | } | |
1349 | new_zhdr = page_address(newpage); | |
1350 | memcpy(new_zhdr, zhdr, PAGE_SIZE); | |
1351 | newpage->private = page->private; | |
1352 | page->private = 0; | |
1353 | z3fold_page_unlock(zhdr); | |
1354 | spin_lock_init(&new_zhdr->page_lock); | |
1355 | new_mapping = page_mapping(page); | |
1356 | __ClearPageMovable(page); | |
1357 | ClearPagePrivate(page); | |
1358 | ||
1359 | get_page(newpage); | |
1360 | z3fold_page_lock(new_zhdr); | |
1361 | if (new_zhdr->first_chunks) | |
1362 | encode_handle(new_zhdr, FIRST); | |
1363 | if (new_zhdr->last_chunks) | |
1364 | encode_handle(new_zhdr, LAST); | |
1365 | if (new_zhdr->middle_chunks) | |
1366 | encode_handle(new_zhdr, MIDDLE); | |
1367 | set_bit(NEEDS_COMPACTING, &newpage->private); | |
1368 | new_zhdr->cpu = smp_processor_id(); | |
1369 | spin_lock(&pool->lock); | |
1370 | list_add(&newpage->lru, &pool->lru); | |
1371 | spin_unlock(&pool->lock); | |
1372 | __SetPageMovable(newpage, new_mapping); | |
1373 | z3fold_page_unlock(new_zhdr); | |
1374 | ||
1375 | queue_work_on(new_zhdr->cpu, pool->compact_wq, &new_zhdr->work); | |
1376 | ||
1377 | page_mapcount_reset(page); | |
1378 | unlock_page(page); | |
1379 | put_page(page); | |
1380 | return 0; | |
1381 | } | |
1382 | ||
1383 | static void z3fold_page_putback(struct page *page) | |
1384 | { | |
1385 | struct z3fold_header *zhdr; | |
1386 | struct z3fold_pool *pool; | |
1387 | ||
1388 | zhdr = page_address(page); | |
1389 | pool = zhdr_to_pool(zhdr); | |
1390 | ||
1391 | z3fold_page_lock(zhdr); | |
1392 | if (!list_empty(&zhdr->buddy)) | |
1393 | list_del_init(&zhdr->buddy); | |
1394 | INIT_LIST_HEAD(&page->lru); | |
1395 | if (kref_put(&zhdr->refcount, release_z3fold_page_locked)) { | |
1396 | atomic64_dec(&pool->pages_nr); | |
1397 | return; | |
1398 | } | |
1399 | spin_lock(&pool->lock); | |
1400 | list_add(&page->lru, &pool->lru); | |
1401 | spin_unlock(&pool->lock); | |
1402 | z3fold_page_unlock(zhdr); | |
1403 | } | |
1404 | ||
1405 | static const struct address_space_operations z3fold_aops = { | |
1406 | .isolate_page = z3fold_page_isolate, | |
1407 | .migratepage = z3fold_page_migrate, | |
1408 | .putback_page = z3fold_page_putback, | |
1409 | }; | |
1410 | ||
9a001fc1 VW |
1411 | /***************** |
1412 | * zpool | |
1413 | ****************/ | |
1414 | ||
1415 | static int z3fold_zpool_evict(struct z3fold_pool *pool, unsigned long handle) | |
1416 | { | |
1417 | if (pool->zpool && pool->zpool_ops && pool->zpool_ops->evict) | |
1418 | return pool->zpool_ops->evict(pool->zpool, handle); | |
1419 | else | |
1420 | return -ENOENT; | |
1421 | } | |
1422 | ||
1423 | static const struct z3fold_ops z3fold_zpool_ops = { | |
1424 | .evict = z3fold_zpool_evict | |
1425 | }; | |
1426 | ||
1427 | static void *z3fold_zpool_create(const char *name, gfp_t gfp, | |
1428 | const struct zpool_ops *zpool_ops, | |
1429 | struct zpool *zpool) | |
1430 | { | |
1431 | struct z3fold_pool *pool; | |
1432 | ||
d30561c5 VW |
1433 | pool = z3fold_create_pool(name, gfp, |
1434 | zpool_ops ? &z3fold_zpool_ops : NULL); | |
9a001fc1 VW |
1435 | if (pool) { |
1436 | pool->zpool = zpool; | |
1437 | pool->zpool_ops = zpool_ops; | |
1438 | } | |
1439 | return pool; | |
1440 | } | |
1441 | ||
1442 | static void z3fold_zpool_destroy(void *pool) | |
1443 | { | |
1444 | z3fold_destroy_pool(pool); | |
1445 | } | |
1446 | ||
1447 | static int z3fold_zpool_malloc(void *pool, size_t size, gfp_t gfp, | |
1448 | unsigned long *handle) | |
1449 | { | |
1450 | return z3fold_alloc(pool, size, gfp, handle); | |
1451 | } | |
1452 | static void z3fold_zpool_free(void *pool, unsigned long handle) | |
1453 | { | |
1454 | z3fold_free(pool, handle); | |
1455 | } | |
1456 | ||
1457 | static int z3fold_zpool_shrink(void *pool, unsigned int pages, | |
1458 | unsigned int *reclaimed) | |
1459 | { | |
1460 | unsigned int total = 0; | |
1461 | int ret = -EINVAL; | |
1462 | ||
1463 | while (total < pages) { | |
1464 | ret = z3fold_reclaim_page(pool, 8); | |
1465 | if (ret < 0) | |
1466 | break; | |
1467 | total++; | |
1468 | } | |
1469 | ||
1470 | if (reclaimed) | |
1471 | *reclaimed = total; | |
1472 | ||
1473 | return ret; | |
1474 | } | |
1475 | ||
1476 | static void *z3fold_zpool_map(void *pool, unsigned long handle, | |
1477 | enum zpool_mapmode mm) | |
1478 | { | |
1479 | return z3fold_map(pool, handle); | |
1480 | } | |
1481 | static void z3fold_zpool_unmap(void *pool, unsigned long handle) | |
1482 | { | |
1483 | z3fold_unmap(pool, handle); | |
1484 | } | |
1485 | ||
1486 | static u64 z3fold_zpool_total_size(void *pool) | |
1487 | { | |
1488 | return z3fold_get_pool_size(pool) * PAGE_SIZE; | |
1489 | } | |
1490 | ||
1491 | static struct zpool_driver z3fold_zpool_driver = { | |
1492 | .type = "z3fold", | |
1493 | .owner = THIS_MODULE, | |
1494 | .create = z3fold_zpool_create, | |
1495 | .destroy = z3fold_zpool_destroy, | |
1496 | .malloc = z3fold_zpool_malloc, | |
1497 | .free = z3fold_zpool_free, | |
1498 | .shrink = z3fold_zpool_shrink, | |
1499 | .map = z3fold_zpool_map, | |
1500 | .unmap = z3fold_zpool_unmap, | |
1501 | .total_size = z3fold_zpool_total_size, | |
1502 | }; | |
1503 | ||
1504 | MODULE_ALIAS("zpool-z3fold"); | |
1505 | ||
1506 | static int __init init_z3fold(void) | |
1507 | { | |
1f862989 VW |
1508 | int ret; |
1509 | ||
ede93213 VW |
1510 | /* Make sure the z3fold header is not larger than the page size */ |
1511 | BUILD_BUG_ON(ZHDR_SIZE_ALIGNED > PAGE_SIZE); | |
1f862989 VW |
1512 | ret = z3fold_mount(); |
1513 | if (ret) | |
1514 | return ret; | |
1515 | ||
9a001fc1 VW |
1516 | zpool_register_driver(&z3fold_zpool_driver); |
1517 | ||
1518 | return 0; | |
1519 | } | |
1520 | ||
1521 | static void __exit exit_z3fold(void) | |
1522 | { | |
1f862989 | 1523 | z3fold_unmount(); |
9a001fc1 VW |
1524 | zpool_unregister_driver(&z3fold_zpool_driver); |
1525 | } | |
1526 | ||
1527 | module_init(init_z3fold); | |
1528 | module_exit(exit_z3fold); | |
1529 | ||
1530 | MODULE_LICENSE("GPL"); | |
1531 | MODULE_AUTHOR("Vitaly Wool <vitalywool@gmail.com>"); | |
1532 | MODULE_DESCRIPTION("3-Fold Allocator for Compressed Pages"); |