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Nitin Gupta61989a82012-01-09 16:51:56 -06001/*
2 * zsmalloc memory allocator
3 *
4 * Copyright (C) 2011 Nitin Gupta
Minchan Kim31fc00b2014-01-30 15:45:55 -08005 * Copyright (C) 2012, 2013 Minchan Kim
Nitin Gupta61989a82012-01-09 16:51:56 -06006 *
7 * This code is released using a dual license strategy: BSD/GPL
8 * You can choose the license that better fits your requirements.
9 *
10 * Released under the terms of 3-clause BSD License
11 * Released under the terms of GNU General Public License Version 2.0
12 */
13
Nitin Gupta2db51da2012-06-09 17:41:14 -070014/*
Nitin Cuptac3e3e882013-12-11 11:04:37 +090015 * This allocator is designed for use with zram. Thus, the allocator is
16 * supposed to work well under low memory conditions. In particular, it
17 * never attempts higher order page allocation which is very likely to
18 * fail under memory pressure. On the other hand, if we just use single
19 * (0-order) pages, it would suffer from very high fragmentation --
20 * any object of size PAGE_SIZE/2 or larger would occupy an entire page.
21 * This was one of the major issues with its predecessor (xvmalloc).
Nitin Gupta2db51da2012-06-09 17:41:14 -070022 *
23 * To overcome these issues, zsmalloc allocates a bunch of 0-order pages
24 * and links them together using various 'struct page' fields. These linked
25 * pages act as a single higher-order page i.e. an object can span 0-order
26 * page boundaries. The code refers to these linked pages as a single entity
27 * called zspage.
28 *
Nitin Cuptac3e3e882013-12-11 11:04:37 +090029 * For simplicity, zsmalloc can only allocate objects of size up to PAGE_SIZE
30 * since this satisfies the requirements of all its current users (in the
31 * worst case, page is incompressible and is thus stored "as-is" i.e. in
32 * uncompressed form). For allocation requests larger than this size, failure
33 * is returned (see zs_malloc).
34 *
35 * Additionally, zs_malloc() does not return a dereferenceable pointer.
36 * Instead, it returns an opaque handle (unsigned long) which encodes actual
37 * location of the allocated object. The reason for this indirection is that
38 * zsmalloc does not keep zspages permanently mapped since that would cause
39 * issues on 32-bit systems where the VA region for kernel space mappings
40 * is very small. So, before using the allocating memory, the object has to
41 * be mapped using zs_map_object() to get a usable pointer and subsequently
42 * unmapped using zs_unmap_object().
43 *
Nitin Gupta2db51da2012-06-09 17:41:14 -070044 * Following is how we use various fields and flags of underlying
45 * struct page(s) to form a zspage.
46 *
47 * Usage of struct page fields:
48 * page->first_page: points to the first component (0-order) page
49 * page->index (union with page->freelist): offset of the first object
50 * starting in this page. For the first page, this is
51 * always 0, so we use this field (aka freelist) to point
52 * to the first free object in zspage.
53 * page->lru: links together all component pages (except the first page)
54 * of a zspage
55 *
56 * For _first_ page only:
57 *
58 * page->private (union with page->first_page): refers to the
59 * component page after the first page
60 * page->freelist: points to the first free object in zspage.
61 * Free objects are linked together using in-place
62 * metadata.
63 * page->objects: maximum number of objects we can store in this
64 * zspage (class->zspage_order * PAGE_SIZE / class->size)
65 * page->lru: links together first pages of various zspages.
66 * Basically forming list of zspages in a fullness group.
67 * page->mapping: class index and fullness group of the zspage
68 *
69 * Usage of struct page flags:
70 * PG_private: identifies the first component page
71 * PG_private2: identifies the last component page
72 *
73 */
74
Nitin Gupta61989a82012-01-09 16:51:56 -060075#ifdef CONFIG_ZSMALLOC_DEBUG
76#define DEBUG
77#endif
78
79#include <linux/module.h>
80#include <linux/kernel.h>
81#include <linux/bitops.h>
82#include <linux/errno.h>
83#include <linux/highmem.h>
Nitin Gupta61989a82012-01-09 16:51:56 -060084#include <linux/string.h>
85#include <linux/slab.h>
86#include <asm/tlbflush.h>
87#include <asm/pgtable.h>
88#include <linux/cpumask.h>
89#include <linux/cpu.h>
Seth Jennings0cbb6132012-02-13 08:47:49 -060090#include <linux/vmalloc.h>
Seth Jenningsc60369f2012-07-18 11:55:55 -050091#include <linux/hardirq.h>
Seth Jennings0959c632012-08-08 15:12:17 +090092#include <linux/spinlock.h>
93#include <linux/types.h>
Minchan Kimbcf16472014-01-30 15:45:50 -080094#include <linux/zsmalloc.h>
Dan Streetmanc7957792014-08-06 16:08:38 -070095#include <linux/zpool.h>
Seth Jennings0959c632012-08-08 15:12:17 +090096
97/*
98 * This must be power of 2 and greater than of equal to sizeof(link_free).
99 * These two conditions ensure that any 'struct link_free' itself doesn't
100 * span more than 1 page which avoids complex case of mapping 2 pages simply
101 * to restore link_free pointer values.
102 */
103#define ZS_ALIGN 8
104
105/*
106 * A single 'zspage' is composed of up to 2^N discontiguous 0-order (single)
107 * pages. ZS_MAX_ZSPAGE_ORDER defines upper limit on N.
108 */
109#define ZS_MAX_ZSPAGE_ORDER 2
110#define ZS_MAX_PAGES_PER_ZSPAGE (_AC(1, UL) << ZS_MAX_ZSPAGE_ORDER)
111
112/*
113 * Object location (<PFN>, <obj_idx>) is encoded as
Nitin Cuptac3e3e882013-12-11 11:04:37 +0900114 * as single (unsigned long) handle value.
Seth Jennings0959c632012-08-08 15:12:17 +0900115 *
116 * Note that object index <obj_idx> is relative to system
117 * page <PFN> it is stored in, so for each sub-page belonging
118 * to a zspage, obj_idx starts with 0.
119 *
120 * This is made more complicated by various memory models and PAE.
121 */
122
123#ifndef MAX_PHYSMEM_BITS
124#ifdef CONFIG_HIGHMEM64G
125#define MAX_PHYSMEM_BITS 36
126#else /* !CONFIG_HIGHMEM64G */
127/*
128 * If this definition of MAX_PHYSMEM_BITS is used, OBJ_INDEX_BITS will just
129 * be PAGE_SHIFT
130 */
131#define MAX_PHYSMEM_BITS BITS_PER_LONG
132#endif
133#endif
134#define _PFN_BITS (MAX_PHYSMEM_BITS - PAGE_SHIFT)
135#define OBJ_INDEX_BITS (BITS_PER_LONG - _PFN_BITS)
136#define OBJ_INDEX_MASK ((_AC(1, UL) << OBJ_INDEX_BITS) - 1)
137
138#define MAX(a, b) ((a) >= (b) ? (a) : (b))
139/* ZS_MIN_ALLOC_SIZE must be multiple of ZS_ALIGN */
140#define ZS_MIN_ALLOC_SIZE \
141 MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS))
142#define ZS_MAX_ALLOC_SIZE PAGE_SIZE
143
144/*
Weijie Yang7eb52512014-06-04 16:11:08 -0700145 * On systems with 4K page size, this gives 255 size classes! There is a
Seth Jennings0959c632012-08-08 15:12:17 +0900146 * trader-off here:
147 * - Large number of size classes is potentially wasteful as free page are
148 * spread across these classes
149 * - Small number of size classes causes large internal fragmentation
150 * - Probably its better to use specific size classes (empirically
151 * determined). NOTE: all those class sizes must be set as multiple of
152 * ZS_ALIGN to make sure link_free itself never has to span 2 pages.
153 *
154 * ZS_MIN_ALLOC_SIZE and ZS_SIZE_CLASS_DELTA must be multiple of ZS_ALIGN
155 * (reason above)
156 */
Seth Jenningsd662b8e2013-01-25 11:46:18 -0600157#define ZS_SIZE_CLASS_DELTA (PAGE_SIZE >> 8)
Seth Jennings0959c632012-08-08 15:12:17 +0900158#define ZS_SIZE_CLASSES ((ZS_MAX_ALLOC_SIZE - ZS_MIN_ALLOC_SIZE) / \
159 ZS_SIZE_CLASS_DELTA + 1)
160
161/*
162 * We do not maintain any list for completely empty or full pages
163 */
164enum fullness_group {
165 ZS_ALMOST_FULL,
166 ZS_ALMOST_EMPTY,
167 _ZS_NR_FULLNESS_GROUPS,
168
169 ZS_EMPTY,
170 ZS_FULL
171};
172
173/*
174 * We assign a page to ZS_ALMOST_EMPTY fullness group when:
175 * n <= N / f, where
176 * n = number of allocated objects
177 * N = total number of objects zspage can store
178 * f = 1/fullness_threshold_frac
179 *
180 * Similarly, we assign zspage to:
181 * ZS_ALMOST_FULL when n > N / f
182 * ZS_EMPTY when n == 0
183 * ZS_FULL when n == N
184 *
185 * (see: fix_fullness_group())
186 */
187static const int fullness_threshold_frac = 4;
188
189struct size_class {
190 /*
191 * Size of objects stored in this class. Must be multiple
192 * of ZS_ALIGN.
193 */
194 int size;
195 unsigned int index;
196
197 /* Number of PAGE_SIZE sized pages to combine to form a 'zspage' */
198 int pages_per_zspage;
199
200 spinlock_t lock;
201
202 /* stats */
203 u64 pages_allocated;
204
205 struct page *fullness_list[_ZS_NR_FULLNESS_GROUPS];
206};
207
208/*
209 * Placed within free objects to form a singly linked list.
210 * For every zspage, first_page->freelist gives head of this list.
211 *
212 * This must be power of 2 and less than or equal to ZS_ALIGN
213 */
214struct link_free {
215 /* Handle of next free chunk (encodes <PFN, obj_idx>) */
216 void *next;
217};
218
219struct zs_pool {
220 struct size_class size_class[ZS_SIZE_CLASSES];
221
222 gfp_t flags; /* allocation flags used when growing pool */
Seth Jennings0959c632012-08-08 15:12:17 +0900223};
Nitin Gupta61989a82012-01-09 16:51:56 -0600224
225/*
226 * A zspage's class index and fullness group
227 * are encoded in its (first)page->mapping
228 */
229#define CLASS_IDX_BITS 28
230#define FULLNESS_BITS 4
231#define CLASS_IDX_MASK ((1 << CLASS_IDX_BITS) - 1)
232#define FULLNESS_MASK ((1 << FULLNESS_BITS) - 1)
233
Seth Jenningsf5536462012-07-18 11:55:56 -0500234struct mapping_area {
Minchan Kim1b945ae2013-12-11 11:04:36 +0900235#ifdef CONFIG_PGTABLE_MAPPING
Seth Jenningsf5536462012-07-18 11:55:56 -0500236 struct vm_struct *vm; /* vm area for mapping object that span pages */
237#else
238 char *vm_buf; /* copy buffer for objects that span pages */
239#endif
240 char *vm_addr; /* address of kmap_atomic()'ed pages */
241 enum zs_mapmode vm_mm; /* mapping mode */
242};
243
Dan Streetmanc7957792014-08-06 16:08:38 -0700244/* zpool driver */
245
246#ifdef CONFIG_ZPOOL
247
248static void *zs_zpool_create(gfp_t gfp, struct zpool_ops *zpool_ops)
249{
250 return zs_create_pool(gfp);
251}
252
253static void zs_zpool_destroy(void *pool)
254{
255 zs_destroy_pool(pool);
256}
257
258static int zs_zpool_malloc(void *pool, size_t size, gfp_t gfp,
259 unsigned long *handle)
260{
261 *handle = zs_malloc(pool, size);
262 return *handle ? 0 : -1;
263}
264static void zs_zpool_free(void *pool, unsigned long handle)
265{
266 zs_free(pool, handle);
267}
268
269static int zs_zpool_shrink(void *pool, unsigned int pages,
270 unsigned int *reclaimed)
271{
272 return -EINVAL;
273}
274
275static void *zs_zpool_map(void *pool, unsigned long handle,
276 enum zpool_mapmode mm)
277{
278 enum zs_mapmode zs_mm;
279
280 switch (mm) {
281 case ZPOOL_MM_RO:
282 zs_mm = ZS_MM_RO;
283 break;
284 case ZPOOL_MM_WO:
285 zs_mm = ZS_MM_WO;
286 break;
287 case ZPOOL_MM_RW: /* fallthru */
288 default:
289 zs_mm = ZS_MM_RW;
290 break;
291 }
292
293 return zs_map_object(pool, handle, zs_mm);
294}
295static void zs_zpool_unmap(void *pool, unsigned long handle)
296{
297 zs_unmap_object(pool, handle);
298}
299
300static u64 zs_zpool_total_size(void *pool)
301{
302 return zs_get_total_size_bytes(pool);
303}
304
305static struct zpool_driver zs_zpool_driver = {
306 .type = "zsmalloc",
307 .owner = THIS_MODULE,
308 .create = zs_zpool_create,
309 .destroy = zs_zpool_destroy,
310 .malloc = zs_zpool_malloc,
311 .free = zs_zpool_free,
312 .shrink = zs_zpool_shrink,
313 .map = zs_zpool_map,
314 .unmap = zs_zpool_unmap,
315 .total_size = zs_zpool_total_size,
316};
317
Kees Cook137f8cf2014-08-29 15:18:40 -0700318MODULE_ALIAS("zpool-zsmalloc");
Dan Streetmanc7957792014-08-06 16:08:38 -0700319#endif /* CONFIG_ZPOOL */
320
Nitin Gupta61989a82012-01-09 16:51:56 -0600321/* per-cpu VM mapping areas for zspage accesses that cross page boundaries */
322static DEFINE_PER_CPU(struct mapping_area, zs_map_area);
323
324static int is_first_page(struct page *page)
325{
Minchan Kima27545bf2012-04-25 15:23:09 +0900326 return PagePrivate(page);
Nitin Gupta61989a82012-01-09 16:51:56 -0600327}
328
329static int is_last_page(struct page *page)
330{
Minchan Kima27545bf2012-04-25 15:23:09 +0900331 return PagePrivate2(page);
Nitin Gupta61989a82012-01-09 16:51:56 -0600332}
333
334static void get_zspage_mapping(struct page *page, unsigned int *class_idx,
335 enum fullness_group *fullness)
336{
337 unsigned long m;
338 BUG_ON(!is_first_page(page));
339
340 m = (unsigned long)page->mapping;
341 *fullness = m & FULLNESS_MASK;
342 *class_idx = (m >> FULLNESS_BITS) & CLASS_IDX_MASK;
343}
344
345static void set_zspage_mapping(struct page *page, unsigned int class_idx,
346 enum fullness_group fullness)
347{
348 unsigned long m;
349 BUG_ON(!is_first_page(page));
350
351 m = ((class_idx & CLASS_IDX_MASK) << FULLNESS_BITS) |
352 (fullness & FULLNESS_MASK);
353 page->mapping = (struct address_space *)m;
354}
355
Nitin Cuptac3e3e882013-12-11 11:04:37 +0900356/*
357 * zsmalloc divides the pool into various size classes where each
358 * class maintains a list of zspages where each zspage is divided
359 * into equal sized chunks. Each allocation falls into one of these
360 * classes depending on its size. This function returns index of the
361 * size class which has chunk size big enough to hold the give size.
362 */
Nitin Gupta61989a82012-01-09 16:51:56 -0600363static int get_size_class_index(int size)
364{
365 int idx = 0;
366
367 if (likely(size > ZS_MIN_ALLOC_SIZE))
368 idx = DIV_ROUND_UP(size - ZS_MIN_ALLOC_SIZE,
369 ZS_SIZE_CLASS_DELTA);
370
371 return idx;
372}
373
Nitin Cuptac3e3e882013-12-11 11:04:37 +0900374/*
375 * For each size class, zspages are divided into different groups
376 * depending on how "full" they are. This was done so that we could
377 * easily find empty or nearly empty zspages when we try to shrink
378 * the pool (not yet implemented). This function returns fullness
379 * status of the given page.
380 */
Nitin Gupta61989a82012-01-09 16:51:56 -0600381static enum fullness_group get_fullness_group(struct page *page)
382{
383 int inuse, max_objects;
384 enum fullness_group fg;
385 BUG_ON(!is_first_page(page));
386
387 inuse = page->inuse;
388 max_objects = page->objects;
389
390 if (inuse == 0)
391 fg = ZS_EMPTY;
392 else if (inuse == max_objects)
393 fg = ZS_FULL;
394 else if (inuse <= max_objects / fullness_threshold_frac)
395 fg = ZS_ALMOST_EMPTY;
396 else
397 fg = ZS_ALMOST_FULL;
398
399 return fg;
400}
401
Nitin Cuptac3e3e882013-12-11 11:04:37 +0900402/*
403 * Each size class maintains various freelists and zspages are assigned
404 * to one of these freelists based on the number of live objects they
405 * have. This functions inserts the given zspage into the freelist
406 * identified by <class, fullness_group>.
407 */
Nitin Gupta61989a82012-01-09 16:51:56 -0600408static void insert_zspage(struct page *page, struct size_class *class,
409 enum fullness_group fullness)
410{
411 struct page **head;
412
413 BUG_ON(!is_first_page(page));
414
415 if (fullness >= _ZS_NR_FULLNESS_GROUPS)
416 return;
417
418 head = &class->fullness_list[fullness];
419 if (*head)
420 list_add_tail(&page->lru, &(*head)->lru);
421
422 *head = page;
423}
424
Nitin Cuptac3e3e882013-12-11 11:04:37 +0900425/*
426 * This function removes the given zspage from the freelist identified
427 * by <class, fullness_group>.
428 */
Nitin Gupta61989a82012-01-09 16:51:56 -0600429static void remove_zspage(struct page *page, struct size_class *class,
430 enum fullness_group fullness)
431{
432 struct page **head;
433
434 BUG_ON(!is_first_page(page));
435
436 if (fullness >= _ZS_NR_FULLNESS_GROUPS)
437 return;
438
439 head = &class->fullness_list[fullness];
440 BUG_ON(!*head);
441 if (list_empty(&(*head)->lru))
442 *head = NULL;
443 else if (*head == page)
444 *head = (struct page *)list_entry((*head)->lru.next,
445 struct page, lru);
446
447 list_del_init(&page->lru);
448}
449
Nitin Cuptac3e3e882013-12-11 11:04:37 +0900450/*
451 * Each size class maintains zspages in different fullness groups depending
452 * on the number of live objects they contain. When allocating or freeing
453 * objects, the fullness status of the page can change, say, from ALMOST_FULL
454 * to ALMOST_EMPTY when freeing an object. This function checks if such
455 * a status change has occurred for the given page and accordingly moves the
456 * page from the freelist of the old fullness group to that of the new
457 * fullness group.
458 */
Nitin Gupta61989a82012-01-09 16:51:56 -0600459static enum fullness_group fix_fullness_group(struct zs_pool *pool,
460 struct page *page)
461{
462 int class_idx;
463 struct size_class *class;
464 enum fullness_group currfg, newfg;
465
466 BUG_ON(!is_first_page(page));
467
468 get_zspage_mapping(page, &class_idx, &currfg);
469 newfg = get_fullness_group(page);
470 if (newfg == currfg)
471 goto out;
472
473 class = &pool->size_class[class_idx];
474 remove_zspage(page, class, currfg);
475 insert_zspage(page, class, newfg);
476 set_zspage_mapping(page, class_idx, newfg);
477
478out:
479 return newfg;
480}
481
482/*
483 * We have to decide on how many pages to link together
484 * to form a zspage for each size class. This is important
485 * to reduce wastage due to unusable space left at end of
486 * each zspage which is given as:
487 * wastage = Zp - Zp % size_class
488 * where Zp = zspage size = k * PAGE_SIZE where k = 1, 2, ...
489 *
490 * For example, for size class of 3/8 * PAGE_SIZE, we should
491 * link together 3 PAGE_SIZE sized pages to form a zspage
492 * since then we can perfectly fit in 8 such objects.
493 */
Minchan Kim2e3b6152012-05-03 15:40:39 +0900494static int get_pages_per_zspage(int class_size)
Nitin Gupta61989a82012-01-09 16:51:56 -0600495{
496 int i, max_usedpc = 0;
497 /* zspage order which gives maximum used size per KB */
498 int max_usedpc_order = 1;
499
Seth Jennings84d4faa2012-03-05 11:33:21 -0600500 for (i = 1; i <= ZS_MAX_PAGES_PER_ZSPAGE; i++) {
Nitin Gupta61989a82012-01-09 16:51:56 -0600501 int zspage_size;
502 int waste, usedpc;
503
504 zspage_size = i * PAGE_SIZE;
505 waste = zspage_size % class_size;
506 usedpc = (zspage_size - waste) * 100 / zspage_size;
507
508 if (usedpc > max_usedpc) {
509 max_usedpc = usedpc;
510 max_usedpc_order = i;
511 }
512 }
513
514 return max_usedpc_order;
515}
516
517/*
518 * A single 'zspage' is composed of many system pages which are
519 * linked together using fields in struct page. This function finds
520 * the first/head page, given any component page of a zspage.
521 */
522static struct page *get_first_page(struct page *page)
523{
524 if (is_first_page(page))
525 return page;
526 else
527 return page->first_page;
528}
529
530static struct page *get_next_page(struct page *page)
531{
532 struct page *next;
533
534 if (is_last_page(page))
535 next = NULL;
536 else if (is_first_page(page))
Sunghan Suhe842b972013-07-12 16:08:13 +0900537 next = (struct page *)page_private(page);
Nitin Gupta61989a82012-01-09 16:51:56 -0600538 else
539 next = list_entry(page->lru.next, struct page, lru);
540
541 return next;
542}
543
Olav Haugan67296872013-11-22 09:30:41 -0800544/*
545 * Encode <page, obj_idx> as a single handle value.
546 * On hardware platforms with physical memory starting at 0x0 the pfn
547 * could be 0 so we ensure that the handle will never be 0 by adjusting the
548 * encoded obj_idx value before encoding.
549 */
Nitin Gupta61989a82012-01-09 16:51:56 -0600550static void *obj_location_to_handle(struct page *page, unsigned long obj_idx)
551{
552 unsigned long handle;
553
554 if (!page) {
555 BUG_ON(obj_idx);
556 return NULL;
557 }
558
559 handle = page_to_pfn(page) << OBJ_INDEX_BITS;
Olav Haugan67296872013-11-22 09:30:41 -0800560 handle |= ((obj_idx + 1) & OBJ_INDEX_MASK);
Nitin Gupta61989a82012-01-09 16:51:56 -0600561
562 return (void *)handle;
563}
564
Olav Haugan67296872013-11-22 09:30:41 -0800565/*
566 * Decode <page, obj_idx> pair from the given object handle. We adjust the
567 * decoded obj_idx back to its original value since it was adjusted in
568 * obj_location_to_handle().
569 */
Minchan Kimc2344342012-06-08 15:39:25 +0900570static void obj_handle_to_location(unsigned long handle, struct page **page,
Nitin Gupta61989a82012-01-09 16:51:56 -0600571 unsigned long *obj_idx)
572{
Minchan Kimc2344342012-06-08 15:39:25 +0900573 *page = pfn_to_page(handle >> OBJ_INDEX_BITS);
Olav Haugan67296872013-11-22 09:30:41 -0800574 *obj_idx = (handle & OBJ_INDEX_MASK) - 1;
Nitin Gupta61989a82012-01-09 16:51:56 -0600575}
576
577static unsigned long obj_idx_to_offset(struct page *page,
578 unsigned long obj_idx, int class_size)
579{
580 unsigned long off = 0;
581
582 if (!is_first_page(page))
583 off = page->index;
584
585 return off + obj_idx * class_size;
586}
587
Nitin Guptaf4477e92012-04-02 09:13:56 -0500588static void reset_page(struct page *page)
589{
590 clear_bit(PG_private, &page->flags);
591 clear_bit(PG_private_2, &page->flags);
592 set_page_private(page, 0);
593 page->mapping = NULL;
594 page->freelist = NULL;
Mel Gorman22b751c2013-02-22 16:34:59 -0800595 page_mapcount_reset(page);
Nitin Guptaf4477e92012-04-02 09:13:56 -0500596}
597
Nitin Gupta61989a82012-01-09 16:51:56 -0600598static void free_zspage(struct page *first_page)
599{
Nitin Guptaf4477e92012-04-02 09:13:56 -0500600 struct page *nextp, *tmp, *head_extra;
Nitin Gupta61989a82012-01-09 16:51:56 -0600601
602 BUG_ON(!is_first_page(first_page));
603 BUG_ON(first_page->inuse);
604
Nitin Guptaf4477e92012-04-02 09:13:56 -0500605 head_extra = (struct page *)page_private(first_page);
Nitin Gupta61989a82012-01-09 16:51:56 -0600606
Nitin Guptaf4477e92012-04-02 09:13:56 -0500607 reset_page(first_page);
Nitin Gupta61989a82012-01-09 16:51:56 -0600608 __free_page(first_page);
609
610 /* zspage with only 1 system page */
Nitin Guptaf4477e92012-04-02 09:13:56 -0500611 if (!head_extra)
Nitin Gupta61989a82012-01-09 16:51:56 -0600612 return;
613
Nitin Guptaf4477e92012-04-02 09:13:56 -0500614 list_for_each_entry_safe(nextp, tmp, &head_extra->lru, lru) {
Nitin Gupta61989a82012-01-09 16:51:56 -0600615 list_del(&nextp->lru);
Nitin Guptaf4477e92012-04-02 09:13:56 -0500616 reset_page(nextp);
Nitin Gupta61989a82012-01-09 16:51:56 -0600617 __free_page(nextp);
618 }
Nitin Guptaf4477e92012-04-02 09:13:56 -0500619 reset_page(head_extra);
620 __free_page(head_extra);
Nitin Gupta61989a82012-01-09 16:51:56 -0600621}
622
623/* Initialize a newly allocated zspage */
624static void init_zspage(struct page *first_page, struct size_class *class)
625{
626 unsigned long off = 0;
627 struct page *page = first_page;
628
629 BUG_ON(!is_first_page(first_page));
630 while (page) {
631 struct page *next_page;
632 struct link_free *link;
633 unsigned int i, objs_on_page;
634
635 /*
636 * page->index stores offset of first object starting
637 * in the page. For the first page, this is always 0,
638 * so we use first_page->index (aka ->freelist) to store
639 * head of corresponding zspage's freelist.
640 */
641 if (page != first_page)
642 page->index = off;
643
644 link = (struct link_free *)kmap_atomic(page) +
645 off / sizeof(*link);
646 objs_on_page = (PAGE_SIZE - off) / class->size;
647
648 for (i = 1; i <= objs_on_page; i++) {
649 off += class->size;
650 if (off < PAGE_SIZE) {
651 link->next = obj_location_to_handle(page, i);
652 link += class->size / sizeof(*link);
653 }
654 }
655
656 /*
657 * We now come to the last (full or partial) object on this
658 * page, which must point to the first object on the next
659 * page (if present)
660 */
661 next_page = get_next_page(page);
662 link->next = obj_location_to_handle(next_page, 0);
663 kunmap_atomic(link);
664 page = next_page;
665 off = (off + class->size) % PAGE_SIZE;
666 }
667}
668
669/*
670 * Allocate a zspage for the given size class
671 */
672static struct page *alloc_zspage(struct size_class *class, gfp_t flags)
673{
674 int i, error;
Seth Jenningsb4b700c2012-06-13 16:03:42 -0500675 struct page *first_page = NULL, *uninitialized_var(prev_page);
Nitin Gupta61989a82012-01-09 16:51:56 -0600676
677 /*
678 * Allocate individual pages and link them together as:
679 * 1. first page->private = first sub-page
680 * 2. all sub-pages are linked together using page->lru
681 * 3. each sub-page is linked to the first page using page->first_page
682 *
683 * For each size class, First/Head pages are linked together using
684 * page->lru. Also, we set PG_private to identify the first page
685 * (i.e. no other sub-page has this flag set) and PG_private_2 to
686 * identify the last page.
687 */
688 error = -ENOMEM;
Minchan Kim2e3b6152012-05-03 15:40:39 +0900689 for (i = 0; i < class->pages_per_zspage; i++) {
Seth Jenningsb4b700c2012-06-13 16:03:42 -0500690 struct page *page;
Nitin Gupta61989a82012-01-09 16:51:56 -0600691
692 page = alloc_page(flags);
693 if (!page)
694 goto cleanup;
695
696 INIT_LIST_HEAD(&page->lru);
697 if (i == 0) { /* first page */
Minchan Kima27545bf2012-04-25 15:23:09 +0900698 SetPagePrivate(page);
Nitin Gupta61989a82012-01-09 16:51:56 -0600699 set_page_private(page, 0);
700 first_page = page;
701 first_page->inuse = 0;
702 }
703 if (i == 1)
Sunghan Suhe842b972013-07-12 16:08:13 +0900704 set_page_private(first_page, (unsigned long)page);
Nitin Gupta61989a82012-01-09 16:51:56 -0600705 if (i >= 1)
706 page->first_page = first_page;
707 if (i >= 2)
708 list_add(&page->lru, &prev_page->lru);
Minchan Kim2e3b6152012-05-03 15:40:39 +0900709 if (i == class->pages_per_zspage - 1) /* last page */
Minchan Kima27545bf2012-04-25 15:23:09 +0900710 SetPagePrivate2(page);
Nitin Gupta61989a82012-01-09 16:51:56 -0600711 prev_page = page;
712 }
713
714 init_zspage(first_page, class);
715
716 first_page->freelist = obj_location_to_handle(first_page, 0);
717 /* Maximum number of objects we can store in this zspage */
Minchan Kim2e3b6152012-05-03 15:40:39 +0900718 first_page->objects = class->pages_per_zspage * PAGE_SIZE / class->size;
Nitin Gupta61989a82012-01-09 16:51:56 -0600719
720 error = 0; /* Success */
721
722cleanup:
723 if (unlikely(error) && first_page) {
724 free_zspage(first_page);
725 first_page = NULL;
726 }
727
728 return first_page;
729}
730
731static struct page *find_get_zspage(struct size_class *class)
732{
733 int i;
734 struct page *page;
735
736 for (i = 0; i < _ZS_NR_FULLNESS_GROUPS; i++) {
737 page = class->fullness_list[i];
738 if (page)
739 break;
740 }
741
742 return page;
743}
744
Minchan Kim1b945ae2013-12-11 11:04:36 +0900745#ifdef CONFIG_PGTABLE_MAPPING
Seth Jenningsf5536462012-07-18 11:55:56 -0500746static inline int __zs_cpu_up(struct mapping_area *area)
Seth Jennings5f601902012-07-02 16:15:49 -0500747{
Seth Jenningsf5536462012-07-18 11:55:56 -0500748 /*
749 * Make sure we don't leak memory if a cpu UP notification
750 * and zs_init() race and both call zs_cpu_up() on the same cpu
751 */
752 if (area->vm)
753 return 0;
754 area->vm = alloc_vm_area(PAGE_SIZE * 2, NULL);
755 if (!area->vm)
756 return -ENOMEM;
757 return 0;
758}
759
760static inline void __zs_cpu_down(struct mapping_area *area)
761{
762 if (area->vm)
763 free_vm_area(area->vm);
764 area->vm = NULL;
765}
766
767static inline void *__zs_map_object(struct mapping_area *area,
768 struct page *pages[2], int off, int size)
769{
WANG Chaof6f8ed42014-08-06 16:06:58 -0700770 BUG_ON(map_vm_area(area->vm, PAGE_KERNEL, pages));
Seth Jenningsf5536462012-07-18 11:55:56 -0500771 area->vm_addr = area->vm->addr;
772 return area->vm_addr + off;
773}
774
775static inline void __zs_unmap_object(struct mapping_area *area,
776 struct page *pages[2], int off, int size)
777{
778 unsigned long addr = (unsigned long)area->vm_addr;
Seth Jenningsf5536462012-07-18 11:55:56 -0500779
Joerg Roedeld95abbb2013-03-27 01:43:14 +0100780 unmap_kernel_range(addr, PAGE_SIZE * 2);
Seth Jenningsf5536462012-07-18 11:55:56 -0500781}
782
Minchan Kim1b945ae2013-12-11 11:04:36 +0900783#else /* CONFIG_PGTABLE_MAPPING */
Seth Jenningsf5536462012-07-18 11:55:56 -0500784
785static inline int __zs_cpu_up(struct mapping_area *area)
786{
787 /*
788 * Make sure we don't leak memory if a cpu UP notification
789 * and zs_init() race and both call zs_cpu_up() on the same cpu
790 */
791 if (area->vm_buf)
792 return 0;
793 area->vm_buf = (char *)__get_free_page(GFP_KERNEL);
794 if (!area->vm_buf)
795 return -ENOMEM;
796 return 0;
797}
798
799static inline void __zs_cpu_down(struct mapping_area *area)
800{
801 if (area->vm_buf)
802 free_page((unsigned long)area->vm_buf);
803 area->vm_buf = NULL;
804}
805
806static void *__zs_map_object(struct mapping_area *area,
807 struct page *pages[2], int off, int size)
808{
Seth Jennings5f601902012-07-02 16:15:49 -0500809 int sizes[2];
810 void *addr;
Seth Jenningsf5536462012-07-18 11:55:56 -0500811 char *buf = area->vm_buf;
Seth Jennings5f601902012-07-02 16:15:49 -0500812
Seth Jenningsf5536462012-07-18 11:55:56 -0500813 /* disable page faults to match kmap_atomic() return conditions */
814 pagefault_disable();
815
816 /* no read fastpath */
817 if (area->vm_mm == ZS_MM_WO)
818 goto out;
Seth Jennings5f601902012-07-02 16:15:49 -0500819
820 sizes[0] = PAGE_SIZE - off;
821 sizes[1] = size - sizes[0];
822
Seth Jennings5f601902012-07-02 16:15:49 -0500823 /* copy object to per-cpu buffer */
824 addr = kmap_atomic(pages[0]);
825 memcpy(buf, addr + off, sizes[0]);
826 kunmap_atomic(addr);
827 addr = kmap_atomic(pages[1]);
828 memcpy(buf + sizes[0], addr, sizes[1]);
829 kunmap_atomic(addr);
Seth Jenningsf5536462012-07-18 11:55:56 -0500830out:
831 return area->vm_buf;
Seth Jennings5f601902012-07-02 16:15:49 -0500832}
833
Seth Jenningsf5536462012-07-18 11:55:56 -0500834static void __zs_unmap_object(struct mapping_area *area,
835 struct page *pages[2], int off, int size)
Seth Jennings5f601902012-07-02 16:15:49 -0500836{
Seth Jennings5f601902012-07-02 16:15:49 -0500837 int sizes[2];
838 void *addr;
Seth Jenningsf5536462012-07-18 11:55:56 -0500839 char *buf = area->vm_buf;
Seth Jennings5f601902012-07-02 16:15:49 -0500840
Seth Jenningsf5536462012-07-18 11:55:56 -0500841 /* no write fastpath */
842 if (area->vm_mm == ZS_MM_RO)
843 goto out;
Seth Jennings5f601902012-07-02 16:15:49 -0500844
845 sizes[0] = PAGE_SIZE - off;
846 sizes[1] = size - sizes[0];
847
848 /* copy per-cpu buffer to object */
849 addr = kmap_atomic(pages[0]);
850 memcpy(addr + off, buf, sizes[0]);
851 kunmap_atomic(addr);
852 addr = kmap_atomic(pages[1]);
853 memcpy(addr, buf + sizes[0], sizes[1]);
854 kunmap_atomic(addr);
Seth Jenningsf5536462012-07-18 11:55:56 -0500855
856out:
857 /* enable page faults to match kunmap_atomic() return conditions */
858 pagefault_enable();
Seth Jennings5f601902012-07-02 16:15:49 -0500859}
Nitin Gupta61989a82012-01-09 16:51:56 -0600860
Minchan Kim1b945ae2013-12-11 11:04:36 +0900861#endif /* CONFIG_PGTABLE_MAPPING */
Seth Jenningsf5536462012-07-18 11:55:56 -0500862
Nitin Gupta61989a82012-01-09 16:51:56 -0600863static int zs_cpu_notifier(struct notifier_block *nb, unsigned long action,
864 void *pcpu)
865{
Seth Jenningsf5536462012-07-18 11:55:56 -0500866 int ret, cpu = (long)pcpu;
Nitin Gupta61989a82012-01-09 16:51:56 -0600867 struct mapping_area *area;
868
869 switch (action) {
870 case CPU_UP_PREPARE:
871 area = &per_cpu(zs_map_area, cpu);
Seth Jenningsf5536462012-07-18 11:55:56 -0500872 ret = __zs_cpu_up(area);
873 if (ret)
874 return notifier_from_errno(ret);
Nitin Gupta61989a82012-01-09 16:51:56 -0600875 break;
876 case CPU_DEAD:
877 case CPU_UP_CANCELED:
878 area = &per_cpu(zs_map_area, cpu);
Seth Jenningsf5536462012-07-18 11:55:56 -0500879 __zs_cpu_down(area);
Nitin Gupta61989a82012-01-09 16:51:56 -0600880 break;
881 }
882
883 return NOTIFY_OK;
884}
885
886static struct notifier_block zs_cpu_nb = {
887 .notifier_call = zs_cpu_notifier
888};
889
890static void zs_exit(void)
891{
892 int cpu;
893
Dan Streetmanc7957792014-08-06 16:08:38 -0700894#ifdef CONFIG_ZPOOL
895 zpool_unregister_driver(&zs_zpool_driver);
896#endif
897
Srivatsa S. Bhatf0e71fc2014-03-11 02:09:59 +0530898 cpu_notifier_register_begin();
899
Nitin Gupta61989a82012-01-09 16:51:56 -0600900 for_each_online_cpu(cpu)
901 zs_cpu_notifier(NULL, CPU_DEAD, (void *)(long)cpu);
Srivatsa S. Bhatf0e71fc2014-03-11 02:09:59 +0530902 __unregister_cpu_notifier(&zs_cpu_nb);
903
904 cpu_notifier_register_done();
Nitin Gupta61989a82012-01-09 16:51:56 -0600905}
906
907static int zs_init(void)
908{
909 int cpu, ret;
910
Srivatsa S. Bhatf0e71fc2014-03-11 02:09:59 +0530911 cpu_notifier_register_begin();
912
913 __register_cpu_notifier(&zs_cpu_nb);
Nitin Gupta61989a82012-01-09 16:51:56 -0600914 for_each_online_cpu(cpu) {
915 ret = zs_cpu_notifier(NULL, CPU_UP_PREPARE, (void *)(long)cpu);
Srivatsa S. Bhatf0e71fc2014-03-11 02:09:59 +0530916 if (notifier_to_errno(ret)) {
917 cpu_notifier_register_done();
Nitin Gupta61989a82012-01-09 16:51:56 -0600918 goto fail;
Srivatsa S. Bhatf0e71fc2014-03-11 02:09:59 +0530919 }
Nitin Gupta61989a82012-01-09 16:51:56 -0600920 }
Srivatsa S. Bhatf0e71fc2014-03-11 02:09:59 +0530921
922 cpu_notifier_register_done();
923
Dan Streetmanc7957792014-08-06 16:08:38 -0700924#ifdef CONFIG_ZPOOL
925 zpool_register_driver(&zs_zpool_driver);
926#endif
927
Nitin Gupta61989a82012-01-09 16:51:56 -0600928 return 0;
929fail:
930 zs_exit();
931 return notifier_to_errno(ret);
932}
933
Davidlohr Bueso4bbc0bc2013-01-04 12:14:00 -0800934/**
935 * zs_create_pool - Creates an allocation pool to work from.
Seth Jennings0d145a52013-01-30 09:36:52 -0600936 * @flags: allocation flags used to allocate pool metadata
Davidlohr Bueso4bbc0bc2013-01-04 12:14:00 -0800937 *
938 * This function must be called before anything when using
939 * the zsmalloc allocator.
940 *
941 * On success, a pointer to the newly created pool is returned,
942 * otherwise NULL.
943 */
Seth Jennings0d145a52013-01-30 09:36:52 -0600944struct zs_pool *zs_create_pool(gfp_t flags)
Nitin Gupta61989a82012-01-09 16:51:56 -0600945{
Ben Hutchings069f1012012-06-20 02:31:11 +0100946 int i, ovhd_size;
Nitin Gupta61989a82012-01-09 16:51:56 -0600947 struct zs_pool *pool;
948
Nitin Gupta61989a82012-01-09 16:51:56 -0600949 ovhd_size = roundup(sizeof(*pool), PAGE_SIZE);
950 pool = kzalloc(ovhd_size, GFP_KERNEL);
951 if (!pool)
952 return NULL;
953
954 for (i = 0; i < ZS_SIZE_CLASSES; i++) {
955 int size;
956 struct size_class *class;
957
958 size = ZS_MIN_ALLOC_SIZE + i * ZS_SIZE_CLASS_DELTA;
959 if (size > ZS_MAX_ALLOC_SIZE)
960 size = ZS_MAX_ALLOC_SIZE;
961
962 class = &pool->size_class[i];
963 class->size = size;
964 class->index = i;
965 spin_lock_init(&class->lock);
Minchan Kim2e3b6152012-05-03 15:40:39 +0900966 class->pages_per_zspage = get_pages_per_zspage(size);
Nitin Gupta61989a82012-01-09 16:51:56 -0600967
968 }
969
Nitin Gupta61989a82012-01-09 16:51:56 -0600970 pool->flags = flags;
Nitin Gupta61989a82012-01-09 16:51:56 -0600971
Nitin Gupta61989a82012-01-09 16:51:56 -0600972 return pool;
973}
974EXPORT_SYMBOL_GPL(zs_create_pool);
975
976void zs_destroy_pool(struct zs_pool *pool)
977{
978 int i;
979
980 for (i = 0; i < ZS_SIZE_CLASSES; i++) {
981 int fg;
982 struct size_class *class = &pool->size_class[i];
983
984 for (fg = 0; fg < _ZS_NR_FULLNESS_GROUPS; fg++) {
985 if (class->fullness_list[fg]) {
Marlies Ruck93ad5ab2013-05-15 16:56:49 -0400986 pr_info("Freeing non-empty class with size %db, fullness group %d\n",
Nitin Gupta61989a82012-01-09 16:51:56 -0600987 class->size, fg);
988 }
989 }
990 }
991 kfree(pool);
992}
993EXPORT_SYMBOL_GPL(zs_destroy_pool);
994
995/**
996 * zs_malloc - Allocate block of given size from pool.
997 * @pool: pool to allocate from
998 * @size: size of block to allocate
Nitin Gupta61989a82012-01-09 16:51:56 -0600999 *
Minchan Kim00a61d82012-05-03 15:40:40 +09001000 * On success, handle to the allocated object is returned,
Minchan Kimc2344342012-06-08 15:39:25 +09001001 * otherwise 0.
Nitin Gupta61989a82012-01-09 16:51:56 -06001002 * Allocation requests with size > ZS_MAX_ALLOC_SIZE will fail.
1003 */
Minchan Kimc2344342012-06-08 15:39:25 +09001004unsigned long zs_malloc(struct zs_pool *pool, size_t size)
Nitin Gupta61989a82012-01-09 16:51:56 -06001005{
Minchan Kimc2344342012-06-08 15:39:25 +09001006 unsigned long obj;
Nitin Gupta61989a82012-01-09 16:51:56 -06001007 struct link_free *link;
1008 int class_idx;
1009 struct size_class *class;
1010
1011 struct page *first_page, *m_page;
1012 unsigned long m_objidx, m_offset;
1013
1014 if (unlikely(!size || size > ZS_MAX_ALLOC_SIZE))
Minchan Kimc2344342012-06-08 15:39:25 +09001015 return 0;
Nitin Gupta61989a82012-01-09 16:51:56 -06001016
1017 class_idx = get_size_class_index(size);
1018 class = &pool->size_class[class_idx];
1019 BUG_ON(class_idx != class->index);
1020
1021 spin_lock(&class->lock);
1022 first_page = find_get_zspage(class);
1023
1024 if (!first_page) {
1025 spin_unlock(&class->lock);
1026 first_page = alloc_zspage(class, pool->flags);
1027 if (unlikely(!first_page))
Minchan Kimc2344342012-06-08 15:39:25 +09001028 return 0;
Nitin Gupta61989a82012-01-09 16:51:56 -06001029
1030 set_zspage_mapping(first_page, class->index, ZS_EMPTY);
1031 spin_lock(&class->lock);
Minchan Kim2e3b6152012-05-03 15:40:39 +09001032 class->pages_allocated += class->pages_per_zspage;
Nitin Gupta61989a82012-01-09 16:51:56 -06001033 }
1034
Minchan Kimc2344342012-06-08 15:39:25 +09001035 obj = (unsigned long)first_page->freelist;
Nitin Gupta61989a82012-01-09 16:51:56 -06001036 obj_handle_to_location(obj, &m_page, &m_objidx);
1037 m_offset = obj_idx_to_offset(m_page, m_objidx, class->size);
1038
1039 link = (struct link_free *)kmap_atomic(m_page) +
1040 m_offset / sizeof(*link);
1041 first_page->freelist = link->next;
1042 memset(link, POISON_INUSE, sizeof(*link));
1043 kunmap_atomic(link);
1044
1045 first_page->inuse++;
1046 /* Now move the zspage to another fullness group, if required */
1047 fix_fullness_group(pool, first_page);
1048 spin_unlock(&class->lock);
1049
1050 return obj;
1051}
1052EXPORT_SYMBOL_GPL(zs_malloc);
1053
Minchan Kimc2344342012-06-08 15:39:25 +09001054void zs_free(struct zs_pool *pool, unsigned long obj)
Nitin Gupta61989a82012-01-09 16:51:56 -06001055{
1056 struct link_free *link;
1057 struct page *first_page, *f_page;
1058 unsigned long f_objidx, f_offset;
1059
1060 int class_idx;
1061 struct size_class *class;
1062 enum fullness_group fullness;
1063
1064 if (unlikely(!obj))
1065 return;
1066
1067 obj_handle_to_location(obj, &f_page, &f_objidx);
1068 first_page = get_first_page(f_page);
1069
1070 get_zspage_mapping(first_page, &class_idx, &fullness);
1071 class = &pool->size_class[class_idx];
1072 f_offset = obj_idx_to_offset(f_page, f_objidx, class->size);
1073
1074 spin_lock(&class->lock);
1075
1076 /* Insert this object in containing zspage's freelist */
1077 link = (struct link_free *)((unsigned char *)kmap_atomic(f_page)
1078 + f_offset);
1079 link->next = first_page->freelist;
1080 kunmap_atomic(link);
Minchan Kimc2344342012-06-08 15:39:25 +09001081 first_page->freelist = (void *)obj;
Nitin Gupta61989a82012-01-09 16:51:56 -06001082
1083 first_page->inuse--;
1084 fullness = fix_fullness_group(pool, first_page);
1085
1086 if (fullness == ZS_EMPTY)
Minchan Kim2e3b6152012-05-03 15:40:39 +09001087 class->pages_allocated -= class->pages_per_zspage;
Nitin Gupta61989a82012-01-09 16:51:56 -06001088
1089 spin_unlock(&class->lock);
1090
1091 if (fullness == ZS_EMPTY)
1092 free_zspage(first_page);
1093}
1094EXPORT_SYMBOL_GPL(zs_free);
1095
Minchan Kim00a61d82012-05-03 15:40:40 +09001096/**
1097 * zs_map_object - get address of allocated object from handle.
1098 * @pool: pool from which the object was allocated
1099 * @handle: handle returned from zs_malloc
1100 *
1101 * Before using an object allocated from zs_malloc, it must be mapped using
1102 * this function. When done with the object, it must be unmapped using
Seth Jennings166cfda2012-07-02 16:15:51 -05001103 * zs_unmap_object.
1104 *
1105 * Only one object can be mapped per cpu at a time. There is no protection
1106 * against nested mappings.
1107 *
1108 * This function returns with preemption and page faults disabled.
Sara Bird396b7fd2013-05-20 15:18:14 -04001109 */
Seth Jenningsb7418512012-07-02 16:15:52 -05001110void *zs_map_object(struct zs_pool *pool, unsigned long handle,
1111 enum zs_mapmode mm)
Nitin Gupta61989a82012-01-09 16:51:56 -06001112{
1113 struct page *page;
1114 unsigned long obj_idx, off;
1115
1116 unsigned int class_idx;
1117 enum fullness_group fg;
1118 struct size_class *class;
1119 struct mapping_area *area;
Seth Jenningsf5536462012-07-18 11:55:56 -05001120 struct page *pages[2];
Nitin Gupta61989a82012-01-09 16:51:56 -06001121
1122 BUG_ON(!handle);
1123
Seth Jenningsc60369f2012-07-18 11:55:55 -05001124 /*
1125 * Because we use per-cpu mapping areas shared among the
1126 * pools/users, we can't allow mapping in interrupt context
1127 * because it can corrupt another users mappings.
1128 */
1129 BUG_ON(in_interrupt());
1130
Nitin Gupta61989a82012-01-09 16:51:56 -06001131 obj_handle_to_location(handle, &page, &obj_idx);
1132 get_zspage_mapping(get_first_page(page), &class_idx, &fg);
1133 class = &pool->size_class[class_idx];
1134 off = obj_idx_to_offset(page, obj_idx, class->size);
1135
1136 area = &get_cpu_var(zs_map_area);
Seth Jenningsf5536462012-07-18 11:55:56 -05001137 area->vm_mm = mm;
Nitin Gupta61989a82012-01-09 16:51:56 -06001138 if (off + class->size <= PAGE_SIZE) {
1139 /* this object is contained entirely within a page */
1140 area->vm_addr = kmap_atomic(page);
Seth Jennings5f601902012-07-02 16:15:49 -05001141 return area->vm_addr + off;
Nitin Gupta61989a82012-01-09 16:51:56 -06001142 }
1143
Seth Jenningsf5536462012-07-18 11:55:56 -05001144 /* this object spans two pages */
1145 pages[0] = page;
1146 pages[1] = get_next_page(page);
1147 BUG_ON(!pages[1]);
Seth Jenningsb7418512012-07-02 16:15:52 -05001148
Seth Jenningsf5536462012-07-18 11:55:56 -05001149 return __zs_map_object(area, pages, off, class->size);
Nitin Gupta61989a82012-01-09 16:51:56 -06001150}
1151EXPORT_SYMBOL_GPL(zs_map_object);
1152
Minchan Kimc2344342012-06-08 15:39:25 +09001153void zs_unmap_object(struct zs_pool *pool, unsigned long handle)
Nitin Gupta61989a82012-01-09 16:51:56 -06001154{
1155 struct page *page;
1156 unsigned long obj_idx, off;
1157
1158 unsigned int class_idx;
1159 enum fullness_group fg;
1160 struct size_class *class;
1161 struct mapping_area *area;
1162
1163 BUG_ON(!handle);
1164
1165 obj_handle_to_location(handle, &page, &obj_idx);
1166 get_zspage_mapping(get_first_page(page), &class_idx, &fg);
1167 class = &pool->size_class[class_idx];
1168 off = obj_idx_to_offset(page, obj_idx, class->size);
1169
Christoph Lameter7c8e0182014-06-04 16:07:56 -07001170 area = this_cpu_ptr(&zs_map_area);
Seth Jenningsf5536462012-07-18 11:55:56 -05001171 if (off + class->size <= PAGE_SIZE)
1172 kunmap_atomic(area->vm_addr);
1173 else {
1174 struct page *pages[2];
Seth Jenningsb7418512012-07-02 16:15:52 -05001175
Seth Jenningsf5536462012-07-18 11:55:56 -05001176 pages[0] = page;
1177 pages[1] = get_next_page(page);
1178 BUG_ON(!pages[1]);
1179
1180 __zs_unmap_object(area, pages, off, class->size);
1181 }
Nitin Gupta61989a82012-01-09 16:51:56 -06001182 put_cpu_var(zs_map_area);
1183}
1184EXPORT_SYMBOL_GPL(zs_unmap_object);
1185
1186u64 zs_get_total_size_bytes(struct zs_pool *pool)
1187{
1188 int i;
1189 u64 npages = 0;
1190
1191 for (i = 0; i < ZS_SIZE_CLASSES; i++)
1192 npages += pool->size_class[i].pages_allocated;
1193
1194 return npages << PAGE_SHIFT;
1195}
1196EXPORT_SYMBOL_GPL(zs_get_total_size_bytes);
Ben Hutchings069f1012012-06-20 02:31:11 +01001197
1198module_init(zs_init);
1199module_exit(zs_exit);
1200
1201MODULE_LICENSE("Dual BSD/GPL");
1202MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");