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1/*
2 * zcache.c
3 *
4 * Copyright (c) 2010,2011, Dan Magenheimer, Oracle Corp.
5 * Copyright (c) 2010,2011, Nitin Gupta
6 *
7 * Zcache provides an in-kernel "host implementation" for transcendent memory
8 * and, thus indirectly, for cleancache and frontswap. Zcache includes two
9 * page-accessible memory [1] interfaces, both utilizing lzo1x compression:
10 * 1) "compression buddies" ("zbud") is used for ephemeral pages
11 * 2) xvmalloc is used for persistent pages.
12 * Xvmalloc (based on the TLSF allocator) has very low fragmentation
13 * so maximizes space efficiency, while zbud allows pairs (and potentially,
14 * in the future, more than a pair of) compressed pages to be closely linked
15 * so that reclaiming can be done via the kernel's physical-page-oriented
16 * "shrinker" interface.
17 *
18 * [1] For a definition of page-accessible memory (aka PAM), see:
19 * http://marc.info/?l=linux-mm&m=127811271605009
20 */
21
22#include <linux/module.h>
23#include <linux/cpu.h>
24#include <linux/highmem.h>
25#include <linux/list.h>
26#include <linux/lzo.h>
27#include <linux/slab.h>
28#include <linux/spinlock.h>
29#include <linux/types.h>
30#include <linux/atomic.h>
31#include <linux/math64.h>
32#include "tmem.h"
33
34#include "../zram/xvmalloc.h" /* if built in drivers/staging */
35
36#if (!defined(CONFIG_CLEANCACHE) && !defined(CONFIG_FRONTSWAP))
37#error "zcache is useless without CONFIG_CLEANCACHE or CONFIG_FRONTSWAP"
38#endif
39#ifdef CONFIG_CLEANCACHE
40#include <linux/cleancache.h>
41#endif
42#ifdef CONFIG_FRONTSWAP
43#include <linux/frontswap.h>
44#endif
45
46#if 0
47/* this is more aggressive but may cause other problems? */
48#define ZCACHE_GFP_MASK (GFP_ATOMIC | __GFP_NORETRY | __GFP_NOWARN)
49#else
50#define ZCACHE_GFP_MASK \
51 (__GFP_FS | __GFP_NORETRY | __GFP_NOWARN | __GFP_NOMEMALLOC)
52#endif
53
54#define MAX_POOLS_PER_CLIENT 16
55
56#define MAX_CLIENTS 16
57#define LOCAL_CLIENT ((uint16_t)-1)
58
59MODULE_LICENSE("GPL");
60
61struct zcache_client {
62 struct tmem_pool *tmem_pools[MAX_POOLS_PER_CLIENT];
63 struct xv_pool *xvpool;
64 bool allocated;
65 atomic_t refcount;
66};
67
68static struct zcache_client zcache_host;
69static struct zcache_client zcache_clients[MAX_CLIENTS];
70
71static inline uint16_t get_client_id_from_client(struct zcache_client *cli)
72{
73 BUG_ON(cli == NULL);
74 if (cli == &zcache_host)
75 return LOCAL_CLIENT;
76 return cli - &zcache_clients[0];
77}
78
79static inline bool is_local_client(struct zcache_client *cli)
80{
81 return cli == &zcache_host;
82}
83
84/**********
85 * Compression buddies ("zbud") provides for packing two (or, possibly
86 * in the future, more) compressed ephemeral pages into a single "raw"
87 * (physical) page and tracking them with data structures so that
88 * the raw pages can be easily reclaimed.
89 *
90 * A zbud page ("zbpg") is an aligned page containing a list_head,
91 * a lock, and two "zbud headers". The remainder of the physical
92 * page is divided up into aligned 64-byte "chunks" which contain
93 * the compressed data for zero, one, or two zbuds. Each zbpg
94 * resides on: (1) an "unused list" if it has no zbuds; (2) a
95 * "buddied" list if it is fully populated with two zbuds; or
96 * (3) one of PAGE_SIZE/64 "unbuddied" lists indexed by how many chunks
97 * the one unbuddied zbud uses. The data inside a zbpg cannot be
98 * read or written unless the zbpg's lock is held.
99 */
100
101#define ZBH_SENTINEL 0x43214321
102#define ZBPG_SENTINEL 0xdeadbeef
103
104#define ZBUD_MAX_BUDS 2
105
106struct zbud_hdr {
107 uint16_t client_id;
108 uint16_t pool_id;
109 struct tmem_oid oid;
110 uint32_t index;
111 uint16_t size; /* compressed size in bytes, zero means unused */
112 DECL_SENTINEL
113};
114
115struct zbud_page {
116 struct list_head bud_list;
117 spinlock_t lock;
118 struct zbud_hdr buddy[ZBUD_MAX_BUDS];
119 DECL_SENTINEL
120 /* followed by NUM_CHUNK aligned CHUNK_SIZE-byte chunks */
121};
122
123#define CHUNK_SHIFT 6
124#define CHUNK_SIZE (1 << CHUNK_SHIFT)
125#define CHUNK_MASK (~(CHUNK_SIZE-1))
126#define NCHUNKS (((PAGE_SIZE - sizeof(struct zbud_page)) & \
127 CHUNK_MASK) >> CHUNK_SHIFT)
128#define MAX_CHUNK (NCHUNKS-1)
129
130static struct {
131 struct list_head list;
132 unsigned count;
133} zbud_unbuddied[NCHUNKS];
134/* list N contains pages with N chunks USED and NCHUNKS-N unused */
135/* element 0 is never used but optimizing that isn't worth it */
136static unsigned long zbud_cumul_chunk_counts[NCHUNKS];
137
138struct list_head zbud_buddied_list;
139static unsigned long zcache_zbud_buddied_count;
140
141/* protects the buddied list and all unbuddied lists */
142static DEFINE_SPINLOCK(zbud_budlists_spinlock);
143
144static LIST_HEAD(zbpg_unused_list);
145static unsigned long zcache_zbpg_unused_list_count;
146
147/* protects the unused page list */
148static DEFINE_SPINLOCK(zbpg_unused_list_spinlock);
149
150static atomic_t zcache_zbud_curr_raw_pages;
151static atomic_t zcache_zbud_curr_zpages;
152static unsigned long zcache_zbud_curr_zbytes;
153static unsigned long zcache_zbud_cumul_zpages;
154static unsigned long zcache_zbud_cumul_zbytes;
155static unsigned long zcache_compress_poor;
156static unsigned long zcache_mean_compress_poor;
157
158/* forward references */
159static void *zcache_get_free_page(void);
160static void zcache_free_page(void *p);
161
162/*
163 * zbud helper functions
164 */
165
166static inline unsigned zbud_max_buddy_size(void)
167{
168 return MAX_CHUNK << CHUNK_SHIFT;
169}
170
171static inline unsigned zbud_size_to_chunks(unsigned size)
172{
173 BUG_ON(size == 0 || size > zbud_max_buddy_size());
174 return (size + CHUNK_SIZE - 1) >> CHUNK_SHIFT;
175}
176
177static inline int zbud_budnum(struct zbud_hdr *zh)
178{
179 unsigned offset = (unsigned long)zh & (PAGE_SIZE - 1);
180 struct zbud_page *zbpg = NULL;
181 unsigned budnum = -1U;
182 int i;
183
184 for (i = 0; i < ZBUD_MAX_BUDS; i++)
185 if (offset == offsetof(typeof(*zbpg), buddy[i])) {
186 budnum = i;
187 break;
188 }
189 BUG_ON(budnum == -1U);
190 return budnum;
191}
192
193static char *zbud_data(struct zbud_hdr *zh, unsigned size)
194{
195 struct zbud_page *zbpg;
196 char *p;
197 unsigned budnum;
198
199 ASSERT_SENTINEL(zh, ZBH);
200 budnum = zbud_budnum(zh);
201 BUG_ON(size == 0 || size > zbud_max_buddy_size());
202 zbpg = container_of(zh, struct zbud_page, buddy[budnum]);
203 ASSERT_SPINLOCK(&zbpg->lock);
204 p = (char *)zbpg;
205 if (budnum == 0)
206 p += ((sizeof(struct zbud_page) + CHUNK_SIZE - 1) &
207 CHUNK_MASK);
208 else if (budnum == 1)
209 p += PAGE_SIZE - ((size + CHUNK_SIZE - 1) & CHUNK_MASK);
210 return p;
211}
212
213/*
214 * zbud raw page management
215 */
216
217static struct zbud_page *zbud_alloc_raw_page(void)
218{
219 struct zbud_page *zbpg = NULL;
220 struct zbud_hdr *zh0, *zh1;
221 bool recycled = 0;
222
223 /* if any pages on the zbpg list, use one */
224 spin_lock(&zbpg_unused_list_spinlock);
225 if (!list_empty(&zbpg_unused_list)) {
226 zbpg = list_first_entry(&zbpg_unused_list,
227 struct zbud_page, bud_list);
228 list_del_init(&zbpg->bud_list);
229 zcache_zbpg_unused_list_count--;
230 recycled = 1;
231 }
232 spin_unlock(&zbpg_unused_list_spinlock);
233 if (zbpg == NULL)
234 /* none on zbpg list, try to get a kernel page */
235 zbpg = zcache_get_free_page();
236 if (likely(zbpg != NULL)) {
237 INIT_LIST_HEAD(&zbpg->bud_list);
238 zh0 = &zbpg->buddy[0]; zh1 = &zbpg->buddy[1];
239 spin_lock_init(&zbpg->lock);
240 if (recycled) {
241 ASSERT_INVERTED_SENTINEL(zbpg, ZBPG);
242 SET_SENTINEL(zbpg, ZBPG);
243 BUG_ON(zh0->size != 0 || tmem_oid_valid(&zh0->oid));
244 BUG_ON(zh1->size != 0 || tmem_oid_valid(&zh1->oid));
245 } else {
246 atomic_inc(&zcache_zbud_curr_raw_pages);
247 INIT_LIST_HEAD(&zbpg->bud_list);
248 SET_SENTINEL(zbpg, ZBPG);
249 zh0->size = 0; zh1->size = 0;
250 tmem_oid_set_invalid(&zh0->oid);
251 tmem_oid_set_invalid(&zh1->oid);
252 }
253 }
254 return zbpg;
255}
256
257static void zbud_free_raw_page(struct zbud_page *zbpg)
258{
259 struct zbud_hdr *zh0 = &zbpg->buddy[0], *zh1 = &zbpg->buddy[1];
260
261 ASSERT_SENTINEL(zbpg, ZBPG);
262 BUG_ON(!list_empty(&zbpg->bud_list));
263 ASSERT_SPINLOCK(&zbpg->lock);
264 BUG_ON(zh0->size != 0 || tmem_oid_valid(&zh0->oid));
265 BUG_ON(zh1->size != 0 || tmem_oid_valid(&zh1->oid));
266 INVERT_SENTINEL(zbpg, ZBPG);
267 spin_unlock(&zbpg->lock);
268 spin_lock(&zbpg_unused_list_spinlock);
269 list_add(&zbpg->bud_list, &zbpg_unused_list);
270 zcache_zbpg_unused_list_count++;
271 spin_unlock(&zbpg_unused_list_spinlock);
272}
273
274/*
275 * core zbud handling routines
276 */
277
278static unsigned zbud_free(struct zbud_hdr *zh)
279{
280 unsigned size;
281
282 ASSERT_SENTINEL(zh, ZBH);
283 BUG_ON(!tmem_oid_valid(&zh->oid));
284 size = zh->size;
285 BUG_ON(zh->size == 0 || zh->size > zbud_max_buddy_size());
286 zh->size = 0;
287 tmem_oid_set_invalid(&zh->oid);
288 INVERT_SENTINEL(zh, ZBH);
289 zcache_zbud_curr_zbytes -= size;
290 atomic_dec(&zcache_zbud_curr_zpages);
291 return size;
292}
293
294static void zbud_free_and_delist(struct zbud_hdr *zh)
295{
296 unsigned chunks;
297 struct zbud_hdr *zh_other;
298 unsigned budnum = zbud_budnum(zh), size;
299 struct zbud_page *zbpg =
300 container_of(zh, struct zbud_page, buddy[budnum]);
301
302 spin_lock(&zbpg->lock);
303 if (list_empty(&zbpg->bud_list)) {
304 /* ignore zombie page... see zbud_evict_pages() */
305 spin_unlock(&zbpg->lock);
306 return;
307 }
308 size = zbud_free(zh);
309 ASSERT_SPINLOCK(&zbpg->lock);
310 zh_other = &zbpg->buddy[(budnum == 0) ? 1 : 0];
311 if (zh_other->size == 0) { /* was unbuddied: unlist and free */
312 chunks = zbud_size_to_chunks(size) ;
313 spin_lock(&zbud_budlists_spinlock);
314 BUG_ON(list_empty(&zbud_unbuddied[chunks].list));
315 list_del_init(&zbpg->bud_list);
316 zbud_unbuddied[chunks].count--;
317 spin_unlock(&zbud_budlists_spinlock);
318 zbud_free_raw_page(zbpg);
319 } else { /* was buddied: move remaining buddy to unbuddied list */
320 chunks = zbud_size_to_chunks(zh_other->size) ;
321 spin_lock(&zbud_budlists_spinlock);
322 list_del_init(&zbpg->bud_list);
323 zcache_zbud_buddied_count--;
324 list_add_tail(&zbpg->bud_list, &zbud_unbuddied[chunks].list);
325 zbud_unbuddied[chunks].count++;
326 spin_unlock(&zbud_budlists_spinlock);
327 spin_unlock(&zbpg->lock);
328 }
329}
330
331static struct zbud_hdr *zbud_create(uint16_t client_id, uint16_t pool_id,
332 struct tmem_oid *oid,
333 uint32_t index, struct page *page,
334 void *cdata, unsigned size)
335{
336 struct zbud_hdr *zh0, *zh1, *zh = NULL;
337 struct zbud_page *zbpg = NULL, *ztmp;
338 unsigned nchunks;
339 char *to;
340 int i, found_good_buddy = 0;
341
342 nchunks = zbud_size_to_chunks(size) ;
343 for (i = MAX_CHUNK - nchunks + 1; i > 0; i--) {
344 spin_lock(&zbud_budlists_spinlock);
345 if (!list_empty(&zbud_unbuddied[i].list)) {
346 list_for_each_entry_safe(zbpg, ztmp,
347 &zbud_unbuddied[i].list, bud_list) {
348 if (spin_trylock(&zbpg->lock)) {
349 found_good_buddy = i;
350 goto found_unbuddied;
351 }
352 }
353 }
354 spin_unlock(&zbud_budlists_spinlock);
355 }
356 /* didn't find a good buddy, try allocating a new page */
357 zbpg = zbud_alloc_raw_page();
358 if (unlikely(zbpg == NULL))
359 goto out;
360 /* ok, have a page, now compress the data before taking locks */
361 spin_lock(&zbpg->lock);
362 spin_lock(&zbud_budlists_spinlock);
363 list_add_tail(&zbpg->bud_list, &zbud_unbuddied[nchunks].list);
364 zbud_unbuddied[nchunks].count++;
365 zh = &zbpg->buddy[0];
366 goto init_zh;
367
368found_unbuddied:
369 ASSERT_SPINLOCK(&zbpg->lock);
370 zh0 = &zbpg->buddy[0]; zh1 = &zbpg->buddy[1];
371 BUG_ON(!((zh0->size == 0) ^ (zh1->size == 0)));
372 if (zh0->size != 0) { /* buddy0 in use, buddy1 is vacant */
373 ASSERT_SENTINEL(zh0, ZBH);
374 zh = zh1;
375 } else if (zh1->size != 0) { /* buddy1 in use, buddy0 is vacant */
376 ASSERT_SENTINEL(zh1, ZBH);
377 zh = zh0;
378 } else
379 BUG();
380 list_del_init(&zbpg->bud_list);
381 zbud_unbuddied[found_good_buddy].count--;
382 list_add_tail(&zbpg->bud_list, &zbud_buddied_list);
383 zcache_zbud_buddied_count++;
384
385init_zh:
386 SET_SENTINEL(zh, ZBH);
387 zh->size = size;
388 zh->index = index;
389 zh->oid = *oid;
390 zh->pool_id = pool_id;
391 zh->client_id = client_id;
392 /* can wait to copy the data until the list locks are dropped */
393 spin_unlock(&zbud_budlists_spinlock);
394
395 to = zbud_data(zh, size);
396 memcpy(to, cdata, size);
397 spin_unlock(&zbpg->lock);
398 zbud_cumul_chunk_counts[nchunks]++;
399 atomic_inc(&zcache_zbud_curr_zpages);
400 zcache_zbud_cumul_zpages++;
401 zcache_zbud_curr_zbytes += size;
402 zcache_zbud_cumul_zbytes += size;
403out:
404 return zh;
405}
406
407static int zbud_decompress(struct page *page, struct zbud_hdr *zh)
408{
409 struct zbud_page *zbpg;
410 unsigned budnum = zbud_budnum(zh);
411 size_t out_len = PAGE_SIZE;
412 char *to_va, *from_va;
413 unsigned size;
414 int ret = 0;
415
416 zbpg = container_of(zh, struct zbud_page, buddy[budnum]);
417 spin_lock(&zbpg->lock);
418 if (list_empty(&zbpg->bud_list)) {
419 /* ignore zombie page... see zbud_evict_pages() */
420 ret = -EINVAL;
421 goto out;
422 }
423 ASSERT_SENTINEL(zh, ZBH);
424 BUG_ON(zh->size == 0 || zh->size > zbud_max_buddy_size());
425 to_va = kmap_atomic(page, KM_USER0);
426 size = zh->size;
427 from_va = zbud_data(zh, size);
428 ret = lzo1x_decompress_safe(from_va, size, to_va, &out_len);
429 BUG_ON(ret != LZO_E_OK);
430 BUG_ON(out_len != PAGE_SIZE);
431 kunmap_atomic(to_va, KM_USER0);
432out:
433 spin_unlock(&zbpg->lock);
434 return ret;
435}
436
437/*
438 * The following routines handle shrinking of ephemeral pages by evicting
439 * pages "least valuable" first.
440 */
441
442static unsigned long zcache_evicted_raw_pages;
443static unsigned long zcache_evicted_buddied_pages;
444static unsigned long zcache_evicted_unbuddied_pages;
445
446static struct tmem_pool *zcache_get_pool_by_id(uint16_t cli_id,
447 uint16_t poolid);
448static void zcache_put_pool(struct tmem_pool *pool);
449
450/*
451 * Flush and free all zbuds in a zbpg, then free the pageframe
452 */
453static void zbud_evict_zbpg(struct zbud_page *zbpg)
454{
455 struct zbud_hdr *zh;
456 int i, j;
457 uint32_t pool_id[ZBUD_MAX_BUDS], client_id[ZBUD_MAX_BUDS];
458 uint32_t index[ZBUD_MAX_BUDS];
459 struct tmem_oid oid[ZBUD_MAX_BUDS];
460 struct tmem_pool *pool;
461
462 ASSERT_SPINLOCK(&zbpg->lock);
463 BUG_ON(!list_empty(&zbpg->bud_list));
464 for (i = 0, j = 0; i < ZBUD_MAX_BUDS; i++) {
465 zh = &zbpg->buddy[i];
466 if (zh->size) {
467 client_id[j] = zh->client_id;
468 pool_id[j] = zh->pool_id;
469 oid[j] = zh->oid;
470 index[j] = zh->index;
471 j++;
472 zbud_free(zh);
473 }
474 }
475 spin_unlock(&zbpg->lock);
476 for (i = 0; i < j; i++) {
477 pool = zcache_get_pool_by_id(client_id[i], pool_id[i]);
478 if (pool != NULL) {
479 tmem_flush_page(pool, &oid[i], index[i]);
480 zcache_put_pool(pool);
481 }
482 }
483 ASSERT_SENTINEL(zbpg, ZBPG);
484 spin_lock(&zbpg->lock);
485 zbud_free_raw_page(zbpg);
486}
487
488/*
489 * Free nr pages. This code is funky because we want to hold the locks
490 * protecting various lists for as short a time as possible, and in some
491 * circumstances the list may change asynchronously when the list lock is
492 * not held. In some cases we also trylock not only to avoid waiting on a
493 * page in use by another cpu, but also to avoid potential deadlock due to
494 * lock inversion.
495 */
496static void zbud_evict_pages(int nr)
497{
498 struct zbud_page *zbpg;
499 int i;
500
501 /* first try freeing any pages on unused list */
502retry_unused_list:
503 spin_lock_bh(&zbpg_unused_list_spinlock);
504 if (!list_empty(&zbpg_unused_list)) {
505 /* can't walk list here, since it may change when unlocked */
506 zbpg = list_first_entry(&zbpg_unused_list,
507 struct zbud_page, bud_list);
508 list_del_init(&zbpg->bud_list);
509 zcache_zbpg_unused_list_count--;
510 atomic_dec(&zcache_zbud_curr_raw_pages);
511 spin_unlock_bh(&zbpg_unused_list_spinlock);
512 zcache_free_page(zbpg);
513 zcache_evicted_raw_pages++;
514 if (--nr <= 0)
515 goto out;
516 goto retry_unused_list;
517 }
518 spin_unlock_bh(&zbpg_unused_list_spinlock);
519
520 /* now try freeing unbuddied pages, starting with least space avail */
521 for (i = 0; i < MAX_CHUNK; i++) {
522retry_unbud_list_i:
523 spin_lock_bh(&zbud_budlists_spinlock);
524 if (list_empty(&zbud_unbuddied[i].list)) {
525 spin_unlock_bh(&zbud_budlists_spinlock);
526 continue;
527 }
528 list_for_each_entry(zbpg, &zbud_unbuddied[i].list, bud_list) {
529 if (unlikely(!spin_trylock(&zbpg->lock)))
530 continue;
531 list_del_init(&zbpg->bud_list);
532 zbud_unbuddied[i].count--;
533 spin_unlock(&zbud_budlists_spinlock);
534 zcache_evicted_unbuddied_pages++;
535 /* want budlists unlocked when doing zbpg eviction */
536 zbud_evict_zbpg(zbpg);
537 local_bh_enable();
538 if (--nr <= 0)
539 goto out;
540 goto retry_unbud_list_i;
541 }
542 spin_unlock_bh(&zbud_budlists_spinlock);
543 }
544
545 /* as a last resort, free buddied pages */
546retry_bud_list:
547 spin_lock_bh(&zbud_budlists_spinlock);
548 if (list_empty(&zbud_buddied_list)) {
549 spin_unlock_bh(&zbud_budlists_spinlock);
550 goto out;
551 }
552 list_for_each_entry(zbpg, &zbud_buddied_list, bud_list) {
553 if (unlikely(!spin_trylock(&zbpg->lock)))
554 continue;
555 list_del_init(&zbpg->bud_list);
556 zcache_zbud_buddied_count--;
557 spin_unlock(&zbud_budlists_spinlock);
558 zcache_evicted_buddied_pages++;
559 /* want budlists unlocked when doing zbpg eviction */
560 zbud_evict_zbpg(zbpg);
561 local_bh_enable();
562 if (--nr <= 0)
563 goto out;
564 goto retry_bud_list;
565 }
566 spin_unlock_bh(&zbud_budlists_spinlock);
567out:
568 return;
569}
570
571static void zbud_init(void)
572{
573 int i;
574
575 INIT_LIST_HEAD(&zbud_buddied_list);
576 zcache_zbud_buddied_count = 0;
577 for (i = 0; i < NCHUNKS; i++) {
578 INIT_LIST_HEAD(&zbud_unbuddied[i].list);
579 zbud_unbuddied[i].count = 0;
580 }
581}
582
583#ifdef CONFIG_SYSFS
584/*
585 * These sysfs routines show a nice distribution of how many zbpg's are
586 * currently (and have ever been placed) in each unbuddied list. It's fun
587 * to watch but can probably go away before final merge.
588 */
589static int zbud_show_unbuddied_list_counts(char *buf)
590{
591 int i;
592 char *p = buf;
593
594 for (i = 0; i < NCHUNKS; i++)
595 p += sprintf(p, "%u ", zbud_unbuddied[i].count);
596 return p - buf;
597}
598
599static int zbud_show_cumul_chunk_counts(char *buf)
600{
601 unsigned long i, chunks = 0, total_chunks = 0, sum_total_chunks = 0;
602 unsigned long total_chunks_lte_21 = 0, total_chunks_lte_32 = 0;
603 unsigned long total_chunks_lte_42 = 0;
604 char *p = buf;
605
606 for (i = 0; i < NCHUNKS; i++) {
607 p += sprintf(p, "%lu ", zbud_cumul_chunk_counts[i]);
608 chunks += zbud_cumul_chunk_counts[i];
609 total_chunks += zbud_cumul_chunk_counts[i];
610 sum_total_chunks += i * zbud_cumul_chunk_counts[i];
611 if (i == 21)
612 total_chunks_lte_21 = total_chunks;
613 if (i == 32)
614 total_chunks_lte_32 = total_chunks;
615 if (i == 42)
616 total_chunks_lte_42 = total_chunks;
617 }
618 p += sprintf(p, "<=21:%lu <=32:%lu <=42:%lu, mean:%lu\n",
619 total_chunks_lte_21, total_chunks_lte_32, total_chunks_lte_42,
620 chunks == 0 ? 0 : sum_total_chunks / chunks);
621 return p - buf;
622}
623#endif
624
625/**********
626 * This "zv" PAM implementation combines the TLSF-based xvMalloc
627 * with lzo1x compression to maximize the amount of data that can
628 * be packed into a physical page.
629 *
630 * Zv represents a PAM page with the index and object (plus a "size" value
631 * necessary for decompression) immediately preceding the compressed data.
632 */
633
634#define ZVH_SENTINEL 0x43214321
635
636struct zv_hdr {
637 uint32_t pool_id;
638 struct tmem_oid oid;
639 uint32_t index;
640 DECL_SENTINEL
641};
642
643/* rudimentary policy limits */
644/* total number of persistent pages may not exceed this percentage */
645static unsigned int zv_page_count_policy_percent = 75;
646/*
647 * byte count defining poor compression; pages with greater zsize will be
648 * rejected
649 */
650static unsigned int zv_max_zsize = (PAGE_SIZE / 8) * 7;
651/*
652 * byte count defining poor *mean* compression; pages with greater zsize
653 * will be rejected until sufficient better-compressed pages are accepted
654 * driving the man below this threshold
655 */
656static unsigned int zv_max_mean_zsize = (PAGE_SIZE / 8) * 5;
657
658static unsigned long zv_curr_dist_counts[NCHUNKS];
659static unsigned long zv_cumul_dist_counts[NCHUNKS];
660
661static struct zv_hdr *zv_create(struct xv_pool *xvpool, uint32_t pool_id,
662 struct tmem_oid *oid, uint32_t index,
663 void *cdata, unsigned clen)
664{
665 struct page *page;
666 struct zv_hdr *zv = NULL;
667 uint32_t offset;
668 int alloc_size = clen + sizeof(struct zv_hdr);
669 int chunks = (alloc_size + (CHUNK_SIZE - 1)) >> CHUNK_SHIFT;
670 int ret;
671
672 BUG_ON(!irqs_disabled());
673 BUG_ON(chunks >= NCHUNKS);
674 ret = xv_malloc(xvpool, alloc_size,
675 &page, &offset, ZCACHE_GFP_MASK);
676 if (unlikely(ret))
677 goto out;
678 zv_curr_dist_counts[chunks]++;
679 zv_cumul_dist_counts[chunks]++;
680 zv = kmap_atomic(page, KM_USER0) + offset;
681 zv->index = index;
682 zv->oid = *oid;
683 zv->pool_id = pool_id;
684 SET_SENTINEL(zv, ZVH);
685 memcpy((char *)zv + sizeof(struct zv_hdr), cdata, clen);
686 kunmap_atomic(zv, KM_USER0);
687out:
688 return zv;
689}
690
691static void zv_free(struct xv_pool *xvpool, struct zv_hdr *zv)
692{
693 unsigned long flags;
694 struct page *page;
695 uint32_t offset;
696 uint16_t size = xv_get_object_size(zv);
697 int chunks = (size + (CHUNK_SIZE - 1)) >> CHUNK_SHIFT;
698
699 ASSERT_SENTINEL(zv, ZVH);
700 BUG_ON(chunks >= NCHUNKS);
701 zv_curr_dist_counts[chunks]--;
702 size -= sizeof(*zv);
703 BUG_ON(size == 0);
704 INVERT_SENTINEL(zv, ZVH);
705 page = virt_to_page(zv);
706 offset = (unsigned long)zv & ~PAGE_MASK;
707 local_irq_save(flags);
708 xv_free(xvpool, page, offset);
709 local_irq_restore(flags);
710}
711
712static void zv_decompress(struct page *page, struct zv_hdr *zv)
713{
714 size_t clen = PAGE_SIZE;
715 char *to_va;
716 unsigned size;
717 int ret;
718
719 ASSERT_SENTINEL(zv, ZVH);
720 size = xv_get_object_size(zv) - sizeof(*zv);
721 BUG_ON(size == 0);
722 to_va = kmap_atomic(page, KM_USER0);
723 ret = lzo1x_decompress_safe((char *)zv + sizeof(*zv),
724 size, to_va, &clen);
725 kunmap_atomic(to_va, KM_USER0);
726 BUG_ON(ret != LZO_E_OK);
727 BUG_ON(clen != PAGE_SIZE);
728}
729
730#ifdef CONFIG_SYSFS
731/*
732 * show a distribution of compression stats for zv pages.
733 */
734
735static int zv_curr_dist_counts_show(char *buf)
736{
737 unsigned long i, n, chunks = 0, sum_total_chunks = 0;
738 char *p = buf;
739
740 for (i = 0; i < NCHUNKS; i++) {
741 n = zv_curr_dist_counts[i];
742 p += sprintf(p, "%lu ", n);
743 chunks += n;
744 sum_total_chunks += i * n;
745 }
746 p += sprintf(p, "mean:%lu\n",
747 chunks == 0 ? 0 : sum_total_chunks / chunks);
748 return p - buf;
749}
750
751static int zv_cumul_dist_counts_show(char *buf)
752{
753 unsigned long i, n, chunks = 0, sum_total_chunks = 0;
754 char *p = buf;
755
756 for (i = 0; i < NCHUNKS; i++) {
757 n = zv_cumul_dist_counts[i];
758 p += sprintf(p, "%lu ", n);
759 chunks += n;
760 sum_total_chunks += i * n;
761 }
762 p += sprintf(p, "mean:%lu\n",
763 chunks == 0 ? 0 : sum_total_chunks / chunks);
764 return p - buf;
765}
766
767/*
768 * setting zv_max_zsize via sysfs causes all persistent (e.g. swap)
769 * pages that don't compress to less than this value (including metadata
770 * overhead) to be rejected. We don't allow the value to get too close
771 * to PAGE_SIZE.
772 */
773static ssize_t zv_max_zsize_show(struct kobject *kobj,
774 struct kobj_attribute *attr,
775 char *buf)
776{
777 return sprintf(buf, "%u\n", zv_max_zsize);
778}
779
780static ssize_t zv_max_zsize_store(struct kobject *kobj,
781 struct kobj_attribute *attr,
782 const char *buf, size_t count)
783{
784 unsigned long val;
785 int err;
786
787 if (!capable(CAP_SYS_ADMIN))
788 return -EPERM;
789
790 err = strict_strtoul(buf, 10, &val);
791 if (err || (val == 0) || (val > (PAGE_SIZE / 8) * 7))
792 return -EINVAL;
793 zv_max_zsize = val;
794 return count;
795}
796
797/*
798 * setting zv_max_mean_zsize via sysfs causes all persistent (e.g. swap)
799 * pages that don't compress to less than this value (including metadata
800 * overhead) to be rejected UNLESS the mean compression is also smaller
801 * than this value. In other words, we are load-balancing-by-zsize the
802 * accepted pages. Again, we don't allow the value to get too close
803 * to PAGE_SIZE.
804 */
805static ssize_t zv_max_mean_zsize_show(struct kobject *kobj,
806 struct kobj_attribute *attr,
807 char *buf)
808{
809 return sprintf(buf, "%u\n", zv_max_mean_zsize);
810}
811
812static ssize_t zv_max_mean_zsize_store(struct kobject *kobj,
813 struct kobj_attribute *attr,
814 const char *buf, size_t count)
815{
816 unsigned long val;
817 int err;
818
819 if (!capable(CAP_SYS_ADMIN))
820 return -EPERM;
821
822 err = strict_strtoul(buf, 10, &val);
823 if (err || (val == 0) || (val > (PAGE_SIZE / 8) * 7))
824 return -EINVAL;
825 zv_max_mean_zsize = val;
826 return count;
827}
828
829/*
830 * setting zv_page_count_policy_percent via sysfs sets an upper bound of
831 * persistent (e.g. swap) pages that will be retained according to:
832 * (zv_page_count_policy_percent * totalram_pages) / 100)
833 * when that limit is reached, further puts will be rejected (until
834 * some pages have been flushed). Note that, due to compression,
835 * this number may exceed 100; it defaults to 75 and we set an
836 * arbitary limit of 150. A poor choice will almost certainly result
837 * in OOM's, so this value should only be changed prudently.
838 */
839static ssize_t zv_page_count_policy_percent_show(struct kobject *kobj,
840 struct kobj_attribute *attr,
841 char *buf)
842{
843 return sprintf(buf, "%u\n", zv_page_count_policy_percent);
844}
845
846static ssize_t zv_page_count_policy_percent_store(struct kobject *kobj,
847 struct kobj_attribute *attr,
848 const char *buf, size_t count)
849{
850 unsigned long val;
851 int err;
852
853 if (!capable(CAP_SYS_ADMIN))
854 return -EPERM;
855
856 err = strict_strtoul(buf, 10, &val);
857 if (err || (val == 0) || (val > 150))
858 return -EINVAL;
859 zv_page_count_policy_percent = val;
860 return count;
861}
862
863static struct kobj_attribute zcache_zv_max_zsize_attr = {
864 .attr = { .name = "zv_max_zsize", .mode = 0644 },
865 .show = zv_max_zsize_show,
866 .store = zv_max_zsize_store,
867};
868
869static struct kobj_attribute zcache_zv_max_mean_zsize_attr = {
870 .attr = { .name = "zv_max_mean_zsize", .mode = 0644 },
871 .show = zv_max_mean_zsize_show,
872 .store = zv_max_mean_zsize_store,
873};
874
875static struct kobj_attribute zcache_zv_page_count_policy_percent_attr = {
876 .attr = { .name = "zv_page_count_policy_percent",
877 .mode = 0644 },
878 .show = zv_page_count_policy_percent_show,
879 .store = zv_page_count_policy_percent_store,
880};
881#endif
882
883/*
884 * zcache core code starts here
885 */
886
887/* useful stats not collected by cleancache or frontswap */
888static unsigned long zcache_flush_total;
889static unsigned long zcache_flush_found;
890static unsigned long zcache_flobj_total;
891static unsigned long zcache_flobj_found;
892static unsigned long zcache_failed_eph_puts;
893static unsigned long zcache_failed_pers_puts;
894
895/*
896 * Tmem operations assume the poolid implies the invoking client.
897 * Zcache only has one client (the kernel itself): LOCAL_CLIENT.
898 * RAMster has each client numbered by cluster node, and a KVM version
899 * of zcache would have one client per guest and each client might
900 * have a poolid==N.
901 */
902static struct tmem_pool *zcache_get_pool_by_id(uint16_t cli_id, uint16_t poolid)
903{
904 struct tmem_pool *pool = NULL;
905 struct zcache_client *cli = NULL;
906
907 if (cli_id == LOCAL_CLIENT)
908 cli = &zcache_host;
909 else {
910 if (cli_id >= MAX_CLIENTS)
911 goto out;
912 cli = &zcache_clients[cli_id];
913 if (cli == NULL)
914 goto out;
915 atomic_inc(&cli->refcount);
916 }
917 if (poolid < MAX_POOLS_PER_CLIENT) {
918 pool = cli->tmem_pools[poolid];
919 if (pool != NULL)
920 atomic_inc(&pool->refcount);
921 }
922out:
923 return pool;
924}
925
926static void zcache_put_pool(struct tmem_pool *pool)
927{
928 struct zcache_client *cli = NULL;
929
930 if (pool == NULL)
931 BUG();
932 cli = pool->client;
933 atomic_dec(&pool->refcount);
934 atomic_dec(&cli->refcount);
935}
936
937int zcache_new_client(uint16_t cli_id)
938{
939 struct zcache_client *cli = NULL;
940 int ret = -1;
941
942 if (cli_id == LOCAL_CLIENT)
943 cli = &zcache_host;
944 else if ((unsigned int)cli_id < MAX_CLIENTS)
945 cli = &zcache_clients[cli_id];
946 if (cli == NULL)
947 goto out;
948 if (cli->allocated)
949 goto out;
950 cli->allocated = 1;
951#ifdef CONFIG_FRONTSWAP
952 cli->xvpool = xv_create_pool();
953 if (cli->xvpool == NULL)
954 goto out;
955#endif
956 ret = 0;
957out:
958 return ret;
959}
960
961/* counters for debugging */
962static unsigned long zcache_failed_get_free_pages;
963static unsigned long zcache_failed_alloc;
964static unsigned long zcache_put_to_flush;
965static unsigned long zcache_aborted_preload;
966static unsigned long zcache_aborted_shrink;
967
968/*
969 * Ensure that memory allocation requests in zcache don't result
970 * in direct reclaim requests via the shrinker, which would cause
971 * an infinite loop. Maybe a GFP flag would be better?
972 */
973static DEFINE_SPINLOCK(zcache_direct_reclaim_lock);
974
975/*
976 * for now, used named slabs so can easily track usage; later can
977 * either just use kmalloc, or perhaps add a slab-like allocator
978 * to more carefully manage total memory utilization
979 */
980static struct kmem_cache *zcache_objnode_cache;
981static struct kmem_cache *zcache_obj_cache;
982static atomic_t zcache_curr_obj_count = ATOMIC_INIT(0);
983static unsigned long zcache_curr_obj_count_max;
984static atomic_t zcache_curr_objnode_count = ATOMIC_INIT(0);
985static unsigned long zcache_curr_objnode_count_max;
986
987/*
988 * to avoid memory allocation recursion (e.g. due to direct reclaim), we
989 * preload all necessary data structures so the hostops callbacks never
990 * actually do a malloc
991 */
992struct zcache_preload {
993 void *page;
994 struct tmem_obj *obj;
995 int nr;
996 struct tmem_objnode *objnodes[OBJNODE_TREE_MAX_PATH];
997};
998static DEFINE_PER_CPU(struct zcache_preload, zcache_preloads) = { 0, };
999
1000static int zcache_do_preload(struct tmem_pool *pool)
1001{
1002 struct zcache_preload *kp;
1003 struct tmem_objnode *objnode;
1004 struct tmem_obj *obj;
1005 void *page;
1006 int ret = -ENOMEM;
1007
1008 if (unlikely(zcache_objnode_cache == NULL))
1009 goto out;
1010 if (unlikely(zcache_obj_cache == NULL))
1011 goto out;
1012 if (!spin_trylock(&zcache_direct_reclaim_lock)) {
1013 zcache_aborted_preload++;
1014 goto out;
1015 }
1016 preempt_disable();
1017 kp = &__get_cpu_var(zcache_preloads);
1018 while (kp->nr < ARRAY_SIZE(kp->objnodes)) {
1019 preempt_enable_no_resched();
1020 objnode = kmem_cache_alloc(zcache_objnode_cache,
1021 ZCACHE_GFP_MASK);
1022 if (unlikely(objnode == NULL)) {
1023 zcache_failed_alloc++;
1024 goto unlock_out;
1025 }
1026 preempt_disable();
1027 kp = &__get_cpu_var(zcache_preloads);
1028 if (kp->nr < ARRAY_SIZE(kp->objnodes))
1029 kp->objnodes[kp->nr++] = objnode;
1030 else
1031 kmem_cache_free(zcache_objnode_cache, objnode);
1032 }
1033 preempt_enable_no_resched();
1034 obj = kmem_cache_alloc(zcache_obj_cache, ZCACHE_GFP_MASK);
1035 if (unlikely(obj == NULL)) {
1036 zcache_failed_alloc++;
1037 goto unlock_out;
1038 }
1039 page = (void *)__get_free_page(ZCACHE_GFP_MASK);
1040 if (unlikely(page == NULL)) {
1041 zcache_failed_get_free_pages++;
1042 kmem_cache_free(zcache_obj_cache, obj);
1043 goto unlock_out;
1044 }
1045 preempt_disable();
1046 kp = &__get_cpu_var(zcache_preloads);
1047 if (kp->obj == NULL)
1048 kp->obj = obj;
1049 else
1050 kmem_cache_free(zcache_obj_cache, obj);
1051 if (kp->page == NULL)
1052 kp->page = page;
1053 else
1054 free_page((unsigned long)page);
1055 ret = 0;
1056unlock_out:
1057 spin_unlock(&zcache_direct_reclaim_lock);
1058out:
1059 return ret;
1060}
1061
1062static void *zcache_get_free_page(void)
1063{
1064 struct zcache_preload *kp;
1065 void *page;
1066
1067 kp = &__get_cpu_var(zcache_preloads);
1068 page = kp->page;
1069 BUG_ON(page == NULL);
1070 kp->page = NULL;
1071 return page;
1072}
1073
1074static void zcache_free_page(void *p)
1075{
1076 free_page((unsigned long)p);
1077}
1078
1079/*
1080 * zcache implementation for tmem host ops
1081 */
1082
1083static struct tmem_objnode *zcache_objnode_alloc(struct tmem_pool *pool)
1084{
1085 struct tmem_objnode *objnode = NULL;
1086 unsigned long count;
1087 struct zcache_preload *kp;
1088
1089 kp = &__get_cpu_var(zcache_preloads);
1090 if (kp->nr <= 0)
1091 goto out;
1092 objnode = kp->objnodes[kp->nr - 1];
1093 BUG_ON(objnode == NULL);
1094 kp->objnodes[kp->nr - 1] = NULL;
1095 kp->nr--;
1096 count = atomic_inc_return(&zcache_curr_objnode_count);
1097 if (count > zcache_curr_objnode_count_max)
1098 zcache_curr_objnode_count_max = count;
1099out:
1100 return objnode;
1101}
1102
1103static void zcache_objnode_free(struct tmem_objnode *objnode,
1104 struct tmem_pool *pool)
1105{
1106 atomic_dec(&zcache_curr_objnode_count);
1107 BUG_ON(atomic_read(&zcache_curr_objnode_count) < 0);
1108 kmem_cache_free(zcache_objnode_cache, objnode);
1109}
1110
1111static struct tmem_obj *zcache_obj_alloc(struct tmem_pool *pool)
1112{
1113 struct tmem_obj *obj = NULL;
1114 unsigned long count;
1115 struct zcache_preload *kp;
1116
1117 kp = &__get_cpu_var(zcache_preloads);
1118 obj = kp->obj;
1119 BUG_ON(obj == NULL);
1120 kp->obj = NULL;
1121 count = atomic_inc_return(&zcache_curr_obj_count);
1122 if (count > zcache_curr_obj_count_max)
1123 zcache_curr_obj_count_max = count;
1124 return obj;
1125}
1126
1127static void zcache_obj_free(struct tmem_obj *obj, struct tmem_pool *pool)
1128{
1129 atomic_dec(&zcache_curr_obj_count);
1130 BUG_ON(atomic_read(&zcache_curr_obj_count) < 0);
1131 kmem_cache_free(zcache_obj_cache, obj);
1132}
1133
1134static struct tmem_hostops zcache_hostops = {
1135 .obj_alloc = zcache_obj_alloc,
1136 .obj_free = zcache_obj_free,
1137 .objnode_alloc = zcache_objnode_alloc,
1138 .objnode_free = zcache_objnode_free,
1139};
1140
1141/*
1142 * zcache implementations for PAM page descriptor ops
1143 */
1144
1145static atomic_t zcache_curr_eph_pampd_count = ATOMIC_INIT(0);
1146static unsigned long zcache_curr_eph_pampd_count_max;
1147static atomic_t zcache_curr_pers_pampd_count = ATOMIC_INIT(0);
1148static unsigned long zcache_curr_pers_pampd_count_max;
1149
1150/* forward reference */
1151static int zcache_compress(struct page *from, void **out_va, size_t *out_len);
1152
1153static void *zcache_pampd_create(char *data, size_t size, bool raw, int eph,
1154 struct tmem_pool *pool, struct tmem_oid *oid,
1155 uint32_t index)
1156{
1157 void *pampd = NULL, *cdata;
1158 size_t clen;
1159 int ret;
1160 unsigned long count;
1161 struct page *page = (struct page *)(data);
1162 struct zcache_client *cli = pool->client;
1163 uint16_t client_id = get_client_id_from_client(cli);
1164 unsigned long zv_mean_zsize;
1165 unsigned long curr_pers_pampd_count;
1166 u64 total_zsize;
1167
1168 if (eph) {
1169 ret = zcache_compress(page, &cdata, &clen);
1170 if (ret == 0)
1171 goto out;
1172 if (clen == 0 || clen > zbud_max_buddy_size()) {
1173 zcache_compress_poor++;
1174 goto out;
1175 }
1176 pampd = (void *)zbud_create(client_id, pool->pool_id, oid,
1177 index, page, cdata, clen);
1178 if (pampd != NULL) {
1179 count = atomic_inc_return(&zcache_curr_eph_pampd_count);
1180 if (count > zcache_curr_eph_pampd_count_max)
1181 zcache_curr_eph_pampd_count_max = count;
1182 }
1183 } else {
1184 curr_pers_pampd_count =
1185 atomic_read(&zcache_curr_pers_pampd_count);
1186 if (curr_pers_pampd_count >
1187 (zv_page_count_policy_percent * totalram_pages) / 100)
1188 goto out;
1189 ret = zcache_compress(page, &cdata, &clen);
1190 if (ret == 0)
1191 goto out;
1192 /* reject if compression is too poor */
1193 if (clen > zv_max_zsize) {
1194 zcache_compress_poor++;
1195 goto out;
1196 }
1197 /* reject if mean compression is too poor */
1198 if ((clen > zv_max_mean_zsize) && (curr_pers_pampd_count > 0)) {
1199 total_zsize = xv_get_total_size_bytes(cli->xvpool);
1200 zv_mean_zsize = div_u64(total_zsize,
1201 curr_pers_pampd_count);
1202 if (zv_mean_zsize > zv_max_mean_zsize) {
1203 zcache_mean_compress_poor++;
1204 goto out;
1205 }
1206 }
1207 pampd = (void *)zv_create(cli->xvpool, pool->pool_id,
1208 oid, index, cdata, clen);
1209 if (pampd == NULL)
1210 goto out;
1211 count = atomic_inc_return(&zcache_curr_pers_pampd_count);
1212 if (count > zcache_curr_pers_pampd_count_max)
1213 zcache_curr_pers_pampd_count_max = count;
1214 }
1215out:
1216 return pampd;
1217}
1218
1219/*
1220 * fill the pageframe corresponding to the struct page with the data
1221 * from the passed pampd
1222 */
1223static int zcache_pampd_get_data(char *data, size_t *bufsize, bool raw,
1224 void *pampd, struct tmem_pool *pool,
1225 struct tmem_oid *oid, uint32_t index)
1226{
1227 int ret = 0;
1228
1229 BUG_ON(is_ephemeral(pool));
1230 zv_decompress((struct page *)(data), pampd);
1231 return ret;
1232}
1233
1234/*
1235 * fill the pageframe corresponding to the struct page with the data
1236 * from the passed pampd
1237 */
1238static int zcache_pampd_get_data_and_free(char *data, size_t *bufsize, bool raw,
1239 void *pampd, struct tmem_pool *pool,
1240 struct tmem_oid *oid, uint32_t index)
1241{
1242 int ret = 0;
1243
1244 BUG_ON(!is_ephemeral(pool));
1245 zbud_decompress((struct page *)(data), pampd);
1246 zbud_free_and_delist((struct zbud_hdr *)pampd);
1247 atomic_dec(&zcache_curr_eph_pampd_count);
1248 return ret;
1249}
1250
1251/*
1252 * free the pampd and remove it from any zcache lists
1253 * pampd must no longer be pointed to from any tmem data structures!
1254 */
1255static void zcache_pampd_free(void *pampd, struct tmem_pool *pool,
1256 struct tmem_oid *oid, uint32_t index)
1257{
1258 struct zcache_client *cli = pool->client;
1259
1260 if (is_ephemeral(pool)) {
1261 zbud_free_and_delist((struct zbud_hdr *)pampd);
1262 atomic_dec(&zcache_curr_eph_pampd_count);
1263 BUG_ON(atomic_read(&zcache_curr_eph_pampd_count) < 0);
1264 } else {
1265 zv_free(cli->xvpool, (struct zv_hdr *)pampd);
1266 atomic_dec(&zcache_curr_pers_pampd_count);
1267 BUG_ON(atomic_read(&zcache_curr_pers_pampd_count) < 0);
1268 }
1269}
1270
1271static void zcache_pampd_free_obj(struct tmem_pool *pool, struct tmem_obj *obj)
1272{
1273}
1274
1275static void zcache_pampd_new_obj(struct tmem_obj *obj)
1276{
1277}
1278
1279static int zcache_pampd_replace_in_obj(void *pampd, struct tmem_obj *obj)
1280{
1281 return -1;
1282}
1283
1284static bool zcache_pampd_is_remote(void *pampd)
1285{
1286 return 0;
1287}
1288
1289static struct tmem_pamops zcache_pamops = {
1290 .create = zcache_pampd_create,
1291 .get_data = zcache_pampd_get_data,
1292 .get_data_and_free = zcache_pampd_get_data_and_free,
1293 .free = zcache_pampd_free,
1294 .free_obj = zcache_pampd_free_obj,
1295 .new_obj = zcache_pampd_new_obj,
1296 .replace_in_obj = zcache_pampd_replace_in_obj,
1297 .is_remote = zcache_pampd_is_remote,
1298};
1299
1300/*
1301 * zcache compression/decompression and related per-cpu stuff
1302 */
1303
1304#define LZO_WORKMEM_BYTES LZO1X_1_MEM_COMPRESS
1305#define LZO_DSTMEM_PAGE_ORDER 1
1306static DEFINE_PER_CPU(unsigned char *, zcache_workmem);
1307static DEFINE_PER_CPU(unsigned char *, zcache_dstmem);
1308
1309static int zcache_compress(struct page *from, void **out_va, size_t *out_len)
1310{
1311 int ret = 0;
1312 unsigned char *dmem = __get_cpu_var(zcache_dstmem);
1313 unsigned char *wmem = __get_cpu_var(zcache_workmem);
1314 char *from_va;
1315
1316 BUG_ON(!irqs_disabled());
1317 if (unlikely(dmem == NULL || wmem == NULL))
1318 goto out; /* no buffer, so can't compress */
1319 from_va = kmap_atomic(from, KM_USER0);
1320 mb();
1321 ret = lzo1x_1_compress(from_va, PAGE_SIZE, dmem, out_len, wmem);
1322 BUG_ON(ret != LZO_E_OK);
1323 *out_va = dmem;
1324 kunmap_atomic(from_va, KM_USER0);
1325 ret = 1;
1326out:
1327 return ret;
1328}
1329
1330
1331static int zcache_cpu_notifier(struct notifier_block *nb,
1332 unsigned long action, void *pcpu)
1333{
1334 int cpu = (long)pcpu;
1335 struct zcache_preload *kp;
1336
1337 switch (action) {
1338 case CPU_UP_PREPARE:
1339 per_cpu(zcache_dstmem, cpu) = (void *)__get_free_pages(
1340 GFP_KERNEL | __GFP_REPEAT,
1341 LZO_DSTMEM_PAGE_ORDER),
1342 per_cpu(zcache_workmem, cpu) =
1343 kzalloc(LZO1X_MEM_COMPRESS,
1344 GFP_KERNEL | __GFP_REPEAT);
1345 break;
1346 case CPU_DEAD:
1347 case CPU_UP_CANCELED:
1348 free_pages((unsigned long)per_cpu(zcache_dstmem, cpu),
1349 LZO_DSTMEM_PAGE_ORDER);
1350 per_cpu(zcache_dstmem, cpu) = NULL;
1351 kfree(per_cpu(zcache_workmem, cpu));
1352 per_cpu(zcache_workmem, cpu) = NULL;
1353 kp = &per_cpu(zcache_preloads, cpu);
1354 while (kp->nr) {
1355 kmem_cache_free(zcache_objnode_cache,
1356 kp->objnodes[kp->nr - 1]);
1357 kp->objnodes[kp->nr - 1] = NULL;
1358 kp->nr--;
1359 }
1360 kmem_cache_free(zcache_obj_cache, kp->obj);
1361 free_page((unsigned long)kp->page);
1362 break;
1363 default:
1364 break;
1365 }
1366 return NOTIFY_OK;
1367}
1368
1369static struct notifier_block zcache_cpu_notifier_block = {
1370 .notifier_call = zcache_cpu_notifier
1371};
1372
1373#ifdef CONFIG_SYSFS
1374#define ZCACHE_SYSFS_RO(_name) \
1375 static ssize_t zcache_##_name##_show(struct kobject *kobj, \
1376 struct kobj_attribute *attr, char *buf) \
1377 { \
1378 return sprintf(buf, "%lu\n", zcache_##_name); \
1379 } \
1380 static struct kobj_attribute zcache_##_name##_attr = { \
1381 .attr = { .name = __stringify(_name), .mode = 0444 }, \
1382 .show = zcache_##_name##_show, \
1383 }
1384
1385#define ZCACHE_SYSFS_RO_ATOMIC(_name) \
1386 static ssize_t zcache_##_name##_show(struct kobject *kobj, \
1387 struct kobj_attribute *attr, char *buf) \
1388 { \
1389 return sprintf(buf, "%d\n", atomic_read(&zcache_##_name)); \
1390 } \
1391 static struct kobj_attribute zcache_##_name##_attr = { \
1392 .attr = { .name = __stringify(_name), .mode = 0444 }, \
1393 .show = zcache_##_name##_show, \
1394 }
1395
1396#define ZCACHE_SYSFS_RO_CUSTOM(_name, _func) \
1397 static ssize_t zcache_##_name##_show(struct kobject *kobj, \
1398 struct kobj_attribute *attr, char *buf) \
1399 { \
1400 return _func(buf); \
1401 } \
1402 static struct kobj_attribute zcache_##_name##_attr = { \
1403 .attr = { .name = __stringify(_name), .mode = 0444 }, \
1404 .show = zcache_##_name##_show, \
1405 }
1406
1407ZCACHE_SYSFS_RO(curr_obj_count_max);
1408ZCACHE_SYSFS_RO(curr_objnode_count_max);
1409ZCACHE_SYSFS_RO(flush_total);
1410ZCACHE_SYSFS_RO(flush_found);
1411ZCACHE_SYSFS_RO(flobj_total);
1412ZCACHE_SYSFS_RO(flobj_found);
1413ZCACHE_SYSFS_RO(failed_eph_puts);
1414ZCACHE_SYSFS_RO(failed_pers_puts);
1415ZCACHE_SYSFS_RO(zbud_curr_zbytes);
1416ZCACHE_SYSFS_RO(zbud_cumul_zpages);
1417ZCACHE_SYSFS_RO(zbud_cumul_zbytes);
1418ZCACHE_SYSFS_RO(zbud_buddied_count);
1419ZCACHE_SYSFS_RO(zbpg_unused_list_count);
1420ZCACHE_SYSFS_RO(evicted_raw_pages);
1421ZCACHE_SYSFS_RO(evicted_unbuddied_pages);
1422ZCACHE_SYSFS_RO(evicted_buddied_pages);
1423ZCACHE_SYSFS_RO(failed_get_free_pages);
1424ZCACHE_SYSFS_RO(failed_alloc);
1425ZCACHE_SYSFS_RO(put_to_flush);
1426ZCACHE_SYSFS_RO(aborted_preload);
1427ZCACHE_SYSFS_RO(aborted_shrink);
1428ZCACHE_SYSFS_RO(compress_poor);
1429ZCACHE_SYSFS_RO(mean_compress_poor);
1430ZCACHE_SYSFS_RO_ATOMIC(zbud_curr_raw_pages);
1431ZCACHE_SYSFS_RO_ATOMIC(zbud_curr_zpages);
1432ZCACHE_SYSFS_RO_ATOMIC(curr_obj_count);
1433ZCACHE_SYSFS_RO_ATOMIC(curr_objnode_count);
1434ZCACHE_SYSFS_RO_CUSTOM(zbud_unbuddied_list_counts,
1435 zbud_show_unbuddied_list_counts);
1436ZCACHE_SYSFS_RO_CUSTOM(zbud_cumul_chunk_counts,
1437 zbud_show_cumul_chunk_counts);
1438ZCACHE_SYSFS_RO_CUSTOM(zv_curr_dist_counts,
1439 zv_curr_dist_counts_show);
1440ZCACHE_SYSFS_RO_CUSTOM(zv_cumul_dist_counts,
1441 zv_cumul_dist_counts_show);
1442
1443static struct attribute *zcache_attrs[] = {
1444 &zcache_curr_obj_count_attr.attr,
1445 &zcache_curr_obj_count_max_attr.attr,
1446 &zcache_curr_objnode_count_attr.attr,
1447 &zcache_curr_objnode_count_max_attr.attr,
1448 &zcache_flush_total_attr.attr,
1449 &zcache_flobj_total_attr.attr,
1450 &zcache_flush_found_attr.attr,
1451 &zcache_flobj_found_attr.attr,
1452 &zcache_failed_eph_puts_attr.attr,
1453 &zcache_failed_pers_puts_attr.attr,
1454 &zcache_compress_poor_attr.attr,
1455 &zcache_mean_compress_poor_attr.attr,
1456 &zcache_zbud_curr_raw_pages_attr.attr,
1457 &zcache_zbud_curr_zpages_attr.attr,
1458 &zcache_zbud_curr_zbytes_attr.attr,
1459 &zcache_zbud_cumul_zpages_attr.attr,
1460 &zcache_zbud_cumul_zbytes_attr.attr,
1461 &zcache_zbud_buddied_count_attr.attr,
1462 &zcache_zbpg_unused_list_count_attr.attr,
1463 &zcache_evicted_raw_pages_attr.attr,
1464 &zcache_evicted_unbuddied_pages_attr.attr,
1465 &zcache_evicted_buddied_pages_attr.attr,
1466 &zcache_failed_get_free_pages_attr.attr,
1467 &zcache_failed_alloc_attr.attr,
1468 &zcache_put_to_flush_attr.attr,
1469 &zcache_aborted_preload_attr.attr,
1470 &zcache_aborted_shrink_attr.attr,
1471 &zcache_zbud_unbuddied_list_counts_attr.attr,
1472 &zcache_zbud_cumul_chunk_counts_attr.attr,
1473 &zcache_zv_curr_dist_counts_attr.attr,
1474 &zcache_zv_cumul_dist_counts_attr.attr,
1475 &zcache_zv_max_zsize_attr.attr,
1476 &zcache_zv_max_mean_zsize_attr.attr,
1477 &zcache_zv_page_count_policy_percent_attr.attr,
1478 NULL,
1479};
1480
1481static struct attribute_group zcache_attr_group = {
1482 .attrs = zcache_attrs,
1483 .name = "zcache",
1484};
1485
1486#endif /* CONFIG_SYSFS */
1487/*
1488 * When zcache is disabled ("frozen"), pools can be created and destroyed,
1489 * but all puts (and thus all other operations that require memory allocation)
1490 * must fail. If zcache is unfrozen, accepts puts, then frozen again,
1491 * data consistency requires all puts while frozen to be converted into
1492 * flushes.
1493 */
1494static bool zcache_freeze;
1495
1496/*
1497 * zcache shrinker interface (only useful for ephemeral pages, so zbud only)
1498 */
1499static int shrink_zcache_memory(struct shrinker *shrink,
1500 struct shrink_control *sc)
1501{
1502 int ret = -1;
1503 int nr = sc->nr_to_scan;
1504 gfp_t gfp_mask = sc->gfp_mask;
1505
1506 if (nr >= 0) {
1507 if (!(gfp_mask & __GFP_FS))
1508 /* does this case really need to be skipped? */
1509 goto out;
1510 if (spin_trylock(&zcache_direct_reclaim_lock)) {
1511 zbud_evict_pages(nr);
1512 spin_unlock(&zcache_direct_reclaim_lock);
1513 } else
1514 zcache_aborted_shrink++;
1515 }
1516 ret = (int)atomic_read(&zcache_zbud_curr_raw_pages);
1517out:
1518 return ret;
1519}
1520
1521static struct shrinker zcache_shrinker = {
1522 .shrink = shrink_zcache_memory,
1523 .seeks = DEFAULT_SEEKS,
1524};
1525
1526/*
1527 * zcache shims between cleancache/frontswap ops and tmem
1528 */
1529
1530static int zcache_put_page(int cli_id, int pool_id, struct tmem_oid *oidp,
1531 uint32_t index, struct page *page)
1532{
1533 struct tmem_pool *pool;
1534 int ret = -1;
1535
1536 BUG_ON(!irqs_disabled());
1537 pool = zcache_get_pool_by_id(cli_id, pool_id);
1538 if (unlikely(pool == NULL))
1539 goto out;
1540 if (!zcache_freeze && zcache_do_preload(pool) == 0) {
1541 /* preload does preempt_disable on success */
1542 ret = tmem_put(pool, oidp, index, (char *)(page),
1543 PAGE_SIZE, 0, is_ephemeral(pool));
1544 if (ret < 0) {
1545 if (is_ephemeral(pool))
1546 zcache_failed_eph_puts++;
1547 else
1548 zcache_failed_pers_puts++;
1549 }
1550 zcache_put_pool(pool);
1551 preempt_enable_no_resched();
1552 } else {
1553 zcache_put_to_flush++;
1554 if (atomic_read(&pool->obj_count) > 0)
1555 /* the put fails whether the flush succeeds or not */
1556 (void)tmem_flush_page(pool, oidp, index);
1557 zcache_put_pool(pool);
1558 }
1559out:
1560 return ret;
1561}
1562
1563static int zcache_get_page(int cli_id, int pool_id, struct tmem_oid *oidp,
1564 uint32_t index, struct page *page)
1565{
1566 struct tmem_pool *pool;
1567 int ret = -1;
1568 unsigned long flags;
1569 size_t size = PAGE_SIZE;
1570
1571 local_irq_save(flags);
1572 pool = zcache_get_pool_by_id(cli_id, pool_id);
1573 if (likely(pool != NULL)) {
1574 if (atomic_read(&pool->obj_count) > 0)
1575 ret = tmem_get(pool, oidp, index, (char *)(page),
1576 &size, 0, is_ephemeral(pool));
1577 zcache_put_pool(pool);
1578 }
1579 local_irq_restore(flags);
1580 return ret;
1581}
1582
1583static int zcache_flush_page(int cli_id, int pool_id,
1584 struct tmem_oid *oidp, uint32_t index)
1585{
1586 struct tmem_pool *pool;
1587 int ret = -1;
1588 unsigned long flags;
1589
1590 local_irq_save(flags);
1591 zcache_flush_total++;
1592 pool = zcache_get_pool_by_id(cli_id, pool_id);
1593 if (likely(pool != NULL)) {
1594 if (atomic_read(&pool->obj_count) > 0)
1595 ret = tmem_flush_page(pool, oidp, index);
1596 zcache_put_pool(pool);
1597 }
1598 if (ret >= 0)
1599 zcache_flush_found++;
1600 local_irq_restore(flags);
1601 return ret;
1602}
1603
1604static int zcache_flush_object(int cli_id, int pool_id,
1605 struct tmem_oid *oidp)
1606{
1607 struct tmem_pool *pool;
1608 int ret = -1;
1609 unsigned long flags;
1610
1611 local_irq_save(flags);
1612 zcache_flobj_total++;
1613 pool = zcache_get_pool_by_id(cli_id, pool_id);
1614 if (likely(pool != NULL)) {
1615 if (atomic_read(&pool->obj_count) > 0)
1616 ret = tmem_flush_object(pool, oidp);
1617 zcache_put_pool(pool);
1618 }
1619 if (ret >= 0)
1620 zcache_flobj_found++;
1621 local_irq_restore(flags);
1622 return ret;
1623}
1624
1625static int zcache_destroy_pool(int cli_id, int pool_id)
1626{
1627 struct tmem_pool *pool = NULL;
1628 struct zcache_client *cli = NULL;
1629 int ret = -1;
1630
1631 if (pool_id < 0)
1632 goto out;
1633 if (cli_id == LOCAL_CLIENT)
1634 cli = &zcache_host;
1635 else if ((unsigned int)cli_id < MAX_CLIENTS)
1636 cli = &zcache_clients[cli_id];
1637 if (cli == NULL)
1638 goto out;
1639 atomic_inc(&cli->refcount);
1640 pool = cli->tmem_pools[pool_id];
1641 if (pool == NULL)
1642 goto out;
1643 cli->tmem_pools[pool_id] = NULL;
1644 /* wait for pool activity on other cpus to quiesce */
1645 while (atomic_read(&pool->refcount) != 0)
1646 ;
1647 atomic_dec(&cli->refcount);
1648 local_bh_disable();
1649 ret = tmem_destroy_pool(pool);
1650 local_bh_enable();
1651 kfree(pool);
1652 pr_info("zcache: destroyed pool id=%d, cli_id=%d\n",
1653 pool_id, cli_id);
1654out:
1655 return ret;
1656}
1657
1658static int zcache_new_pool(uint16_t cli_id, uint32_t flags)
1659{
1660 int poolid = -1;
1661 struct tmem_pool *pool;
1662 struct zcache_client *cli = NULL;
1663
1664 if (cli_id == LOCAL_CLIENT)
1665 cli = &zcache_host;
1666 else if ((unsigned int)cli_id < MAX_CLIENTS)
1667 cli = &zcache_clients[cli_id];
1668 if (cli == NULL)
1669 goto out;
1670 atomic_inc(&cli->refcount);
1671 pool = kmalloc(sizeof(struct tmem_pool), GFP_KERNEL);
1672 if (pool == NULL) {
1673 pr_info("zcache: pool creation failed: out of memory\n");
1674 goto out;
1675 }
1676
1677 for (poolid = 0; poolid < MAX_POOLS_PER_CLIENT; poolid++)
1678 if (cli->tmem_pools[poolid] == NULL)
1679 break;
1680 if (poolid >= MAX_POOLS_PER_CLIENT) {
1681 pr_info("zcache: pool creation failed: max exceeded\n");
1682 kfree(pool);
1683 poolid = -1;
1684 goto out;
1685 }
1686 atomic_set(&pool->refcount, 0);
1687 pool->client = cli;
1688 pool->pool_id = poolid;
1689 tmem_new_pool(pool, flags);
1690 cli->tmem_pools[poolid] = pool;
1691 pr_info("zcache: created %s tmem pool, id=%d, client=%d\n",
1692 flags & TMEM_POOL_PERSIST ? "persistent" : "ephemeral",
1693 poolid, cli_id);
1694out:
1695 if (cli != NULL)
1696 atomic_dec(&cli->refcount);
1697 return poolid;
1698}
1699
1700/**********
1701 * Two kernel functionalities currently can be layered on top of tmem.
1702 * These are "cleancache" which is used as a second-chance cache for clean
1703 * page cache pages; and "frontswap" which is used for swap pages
1704 * to avoid writes to disk. A generic "shim" is provided here for each
1705 * to translate in-kernel semantics to zcache semantics.
1706 */
1707
1708#ifdef CONFIG_CLEANCACHE
1709static void zcache_cleancache_put_page(int pool_id,
1710 struct cleancache_filekey key,
1711 pgoff_t index, struct page *page)
1712{
1713 u32 ind = (u32) index;
1714 struct tmem_oid oid = *(struct tmem_oid *)&key;
1715
1716 if (likely(ind == index))
1717 (void)zcache_put_page(LOCAL_CLIENT, pool_id, &oid, index, page);
1718}
1719
1720static int zcache_cleancache_get_page(int pool_id,
1721 struct cleancache_filekey key,
1722 pgoff_t index, struct page *page)
1723{
1724 u32 ind = (u32) index;
1725 struct tmem_oid oid = *(struct tmem_oid *)&key;
1726 int ret = -1;
1727
1728 if (likely(ind == index))
1729 ret = zcache_get_page(LOCAL_CLIENT, pool_id, &oid, index, page);
1730 return ret;
1731}
1732
1733static void zcache_cleancache_flush_page(int pool_id,
1734 struct cleancache_filekey key,
1735 pgoff_t index)
1736{
1737 u32 ind = (u32) index;
1738 struct tmem_oid oid = *(struct tmem_oid *)&key;
1739
1740 if (likely(ind == index))
1741 (void)zcache_flush_page(LOCAL_CLIENT, pool_id, &oid, ind);
1742}
1743
1744static void zcache_cleancache_flush_inode(int pool_id,
1745 struct cleancache_filekey key)
1746{
1747 struct tmem_oid oid = *(struct tmem_oid *)&key;
1748
1749 (void)zcache_flush_object(LOCAL_CLIENT, pool_id, &oid);
1750}
1751
1752static void zcache_cleancache_flush_fs(int pool_id)
1753{
1754 if (pool_id >= 0)
1755 (void)zcache_destroy_pool(LOCAL_CLIENT, pool_id);
1756}
1757
1758static int zcache_cleancache_init_fs(size_t pagesize)
1759{
1760 BUG_ON(sizeof(struct cleancache_filekey) !=
1761 sizeof(struct tmem_oid));
1762 BUG_ON(pagesize != PAGE_SIZE);
1763 return zcache_new_pool(LOCAL_CLIENT, 0);
1764}
1765
1766static int zcache_cleancache_init_shared_fs(char *uuid, size_t pagesize)
1767{
1768 /* shared pools are unsupported and map to private */
1769 BUG_ON(sizeof(struct cleancache_filekey) !=
1770 sizeof(struct tmem_oid));
1771 BUG_ON(pagesize != PAGE_SIZE);
1772 return zcache_new_pool(LOCAL_CLIENT, 0);
1773}
1774
1775static struct cleancache_ops zcache_cleancache_ops = {
1776 .put_page = zcache_cleancache_put_page,
1777 .get_page = zcache_cleancache_get_page,
1778 .flush_page = zcache_cleancache_flush_page,
1779 .flush_inode = zcache_cleancache_flush_inode,
1780 .flush_fs = zcache_cleancache_flush_fs,
1781 .init_shared_fs = zcache_cleancache_init_shared_fs,
1782 .init_fs = zcache_cleancache_init_fs
1783};
1784
1785struct cleancache_ops zcache_cleancache_register_ops(void)
1786{
1787 struct cleancache_ops old_ops =
1788 cleancache_register_ops(&zcache_cleancache_ops);
1789
1790 return old_ops;
1791}
1792#endif
1793
1794#ifdef CONFIG_FRONTSWAP
1795/* a single tmem poolid is used for all frontswap "types" (swapfiles) */
1796static int zcache_frontswap_poolid = -1;
1797
1798/*
1799 * Swizzling increases objects per swaptype, increasing tmem concurrency
1800 * for heavy swaploads. Later, larger nr_cpus -> larger SWIZ_BITS
1801 */
1802#define SWIZ_BITS 4
1803#define SWIZ_MASK ((1 << SWIZ_BITS) - 1)
1804#define _oswiz(_type, _ind) ((_type << SWIZ_BITS) | (_ind & SWIZ_MASK))
1805#define iswiz(_ind) (_ind >> SWIZ_BITS)
1806
1807static inline struct tmem_oid oswiz(unsigned type, u32 ind)
1808{
1809 struct tmem_oid oid = { .oid = { 0 } };
1810 oid.oid[0] = _oswiz(type, ind);
1811 return oid;
1812}
1813
1814static int zcache_frontswap_put_page(unsigned type, pgoff_t offset,
1815 struct page *page)
1816{
1817 u64 ind64 = (u64)offset;
1818 u32 ind = (u32)offset;
1819 struct tmem_oid oid = oswiz(type, ind);
1820 int ret = -1;
1821 unsigned long flags;
1822
1823 BUG_ON(!PageLocked(page));
1824 if (likely(ind64 == ind)) {
1825 local_irq_save(flags);
1826 ret = zcache_put_page(LOCAL_CLIENT, zcache_frontswap_poolid,
1827 &oid, iswiz(ind), page);
1828 local_irq_restore(flags);
1829 }
1830 return ret;
1831}
1832
1833/* returns 0 if the page was successfully gotten from frontswap, -1 if
1834 * was not present (should never happen!) */
1835static int zcache_frontswap_get_page(unsigned type, pgoff_t offset,
1836 struct page *page)
1837{
1838 u64 ind64 = (u64)offset;
1839 u32 ind = (u32)offset;
1840 struct tmem_oid oid = oswiz(type, ind);
1841 int ret = -1;
1842
1843 BUG_ON(!PageLocked(page));
1844 if (likely(ind64 == ind))
1845 ret = zcache_get_page(LOCAL_CLIENT, zcache_frontswap_poolid,
1846 &oid, iswiz(ind), page);
1847 return ret;
1848}
1849
1850/* flush a single page from frontswap */
1851static void zcache_frontswap_flush_page(unsigned type, pgoff_t offset)
1852{
1853 u64 ind64 = (u64)offset;
1854 u32 ind = (u32)offset;
1855 struct tmem_oid oid = oswiz(type, ind);
1856
1857 if (likely(ind64 == ind))
1858 (void)zcache_flush_page(LOCAL_CLIENT, zcache_frontswap_poolid,
1859 &oid, iswiz(ind));
1860}
1861
1862/* flush all pages from the passed swaptype */
1863static void zcache_frontswap_flush_area(unsigned type)
1864{
1865 struct tmem_oid oid;
1866 int ind;
1867
1868 for (ind = SWIZ_MASK; ind >= 0; ind--) {
1869 oid = oswiz(type, ind);
1870 (void)zcache_flush_object(LOCAL_CLIENT,
1871 zcache_frontswap_poolid, &oid);
1872 }
1873}
1874
1875static void zcache_frontswap_init(unsigned ignored)
1876{
1877 /* a single tmem poolid is used for all frontswap "types" (swapfiles) */
1878 if (zcache_frontswap_poolid < 0)
1879 zcache_frontswap_poolid =
1880 zcache_new_pool(LOCAL_CLIENT, TMEM_POOL_PERSIST);
1881}
1882
1883static struct frontswap_ops zcache_frontswap_ops = {
1884 .put_page = zcache_frontswap_put_page,
1885 .get_page = zcache_frontswap_get_page,
1886 .flush_page = zcache_frontswap_flush_page,
1887 .flush_area = zcache_frontswap_flush_area,
1888 .init = zcache_frontswap_init
1889};
1890
1891struct frontswap_ops zcache_frontswap_register_ops(void)
1892{
1893 struct frontswap_ops old_ops =
1894 frontswap_register_ops(&zcache_frontswap_ops);
1895
1896 return old_ops;
1897}
1898#endif
1899
1900/*
1901 * zcache initialization
1902 * NOTE FOR NOW zcache MUST BE PROVIDED AS A KERNEL BOOT PARAMETER OR
1903 * NOTHING HAPPENS!
1904 */
1905
1906static int zcache_enabled;
1907
1908static int __init enable_zcache(char *s)
1909{
1910 zcache_enabled = 1;
1911 return 1;
1912}
1913__setup("zcache", enable_zcache);
1914
1915/* allow independent dynamic disabling of cleancache and frontswap */
1916
1917static int use_cleancache = 1;
1918
1919static int __init no_cleancache(char *s)
1920{
1921 use_cleancache = 0;
1922 return 1;
1923}
1924
1925__setup("nocleancache", no_cleancache);
1926
1927static int use_frontswap = 1;
1928
1929static int __init no_frontswap(char *s)
1930{
1931 use_frontswap = 0;
1932 return 1;
1933}
1934
1935__setup("nofrontswap", no_frontswap);
1936
1937static int __init zcache_init(void)
1938{
1939 int ret = 0;
1940
1941#ifdef CONFIG_SYSFS
1942 ret = sysfs_create_group(mm_kobj, &zcache_attr_group);
1943 if (ret) {
1944 pr_err("zcache: can't create sysfs\n");
1945 goto out;
1946 }
1947#endif /* CONFIG_SYSFS */
1948#if defined(CONFIG_CLEANCACHE) || defined(CONFIG_FRONTSWAP)
1949 if (zcache_enabled) {
1950 unsigned int cpu;
1951
1952 tmem_register_hostops(&zcache_hostops);
1953 tmem_register_pamops(&zcache_pamops);
1954 ret = register_cpu_notifier(&zcache_cpu_notifier_block);
1955 if (ret) {
1956 pr_err("zcache: can't register cpu notifier\n");
1957 goto out;
1958 }
1959 for_each_online_cpu(cpu) {
1960 void *pcpu = (void *)(long)cpu;
1961 zcache_cpu_notifier(&zcache_cpu_notifier_block,
1962 CPU_UP_PREPARE, pcpu);
1963 }
1964 }
1965 zcache_objnode_cache = kmem_cache_create("zcache_objnode",
1966 sizeof(struct tmem_objnode), 0, 0, NULL);
1967 zcache_obj_cache = kmem_cache_create("zcache_obj",
1968 sizeof(struct tmem_obj), 0, 0, NULL);
1969 ret = zcache_new_client(LOCAL_CLIENT);
1970 if (ret) {
1971 pr_err("zcache: can't create client\n");
1972 goto out;
1973 }
1974#endif
1975#ifdef CONFIG_CLEANCACHE
1976 if (zcache_enabled && use_cleancache) {
1977 struct cleancache_ops old_ops;
1978
1979 zbud_init();
1980 register_shrinker(&zcache_shrinker);
1981 old_ops = zcache_cleancache_register_ops();
1982 pr_info("zcache: cleancache enabled using kernel "
1983 "transcendent memory and compression buddies\n");
1984 if (old_ops.init_fs != NULL)
1985 pr_warning("zcache: cleancache_ops overridden");
1986 }
1987#endif
1988#ifdef CONFIG_FRONTSWAP
1989 if (zcache_enabled && use_frontswap) {
1990 struct frontswap_ops old_ops;
1991
1992 old_ops = zcache_frontswap_register_ops();
1993 pr_info("zcache: frontswap enabled using kernel "
1994 "transcendent memory and xvmalloc\n");
1995 if (old_ops.init != NULL)
1996 pr_warning("ktmem: frontswap_ops overridden");
1997 }
1998#endif
1999out:
2000 return ret;
2001}
2002
2003module_init(zcache_init)