drivers/staging/zcache/zcache-main.c

   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 the crypto compression
  10  * API:
  11  * 1) "compression buddies" ("zbud") is used for ephemeral pages
  12  * 2) zsmalloc is used for persistent pages.
  13  * Xvmalloc (based on the TLSF allocator) has very low fragmentation
  14  * so maximizes space efficiency, while zbud allows pairs (and potentially,
  15  * in the future, more than a pair of) compressed pages to be closely linked
  16  * so that reclaiming can be done via the kernel's physical-page-oriented
  17  * "shrinker" interface.
  18  *
  19  * [1] For a definition of page-accessible memory (aka PAM), see:
  20  *   http://marc.info/?l=linux-mm&m=127811271605009
  21  */
  22
  23 #include <linux/module.h>
  24 #include <linux/cpu.h>
  25 #include <linux/highmem.h>
  26 #include <linux/list.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 <linux/crypto.h>
  33 #include <linux/string.h>
  34 #include "tmem.h"
  35
  36 #include "../zsmalloc/zsmalloc.h"
  37
  38 #if (!defined(CONFIG_CLEANCACHE) && !defined(CONFIG_FRONTSWAP))
  39 #error "zcache is useless without CONFIG_CLEANCACHE or CONFIG_FRONTSWAP"
  40 #endif
  41 #ifdef CONFIG_CLEANCACHE
  42 #include <linux/cleancache.h>
  43 #endif
  44 #ifdef CONFIG_FRONTSWAP
  45 #include <linux/frontswap.h>
  46 #endif
  47
  48 #if 0
  49 /* this is more aggressive but may cause other problems? */
  50 #define ZCACHE_GFP_MASK (GFP_ATOMIC | __GFP_NORETRY | __GFP_NOWARN)
  51 #else
  52 #define ZCACHE_GFP_MASK \
  53         (__GFP_FS | __GFP_NORETRY | __GFP_NOWARN | __GFP_NOMEMALLOC)
  54 #endif
  55
  56 #define MAX_POOLS_PER_CLIENT 16
  57
  58 #define MAX_CLIENTS 16
  59 #define LOCAL_CLIENT ((uint16_t)-1)
  60
  61 MODULE_LICENSE("GPL");
  62
  63 struct zcache_client {
  64         struct tmem_pool *tmem_pools[MAX_POOLS_PER_CLIENT];
  65         struct zs_pool *zspool;
  66         bool allocated;
  67         atomic_t refcount;
  68 };
  69
  70 static struct zcache_client zcache_host;
  71 static struct zcache_client zcache_clients[MAX_CLIENTS];
  72
  73 static inline uint16_t get_client_id_from_client(struct zcache_client *cli)
  74 {
  75         BUG_ON(cli == NULL);
  76         if (cli == &zcache_host)
  77                 return LOCAL_CLIENT;
  78         return cli - &zcache_clients[0];
  79 }
  80
  81 static inline bool is_local_client(struct zcache_client *cli)
  82 {
  83         return cli == &zcache_host;
  84 }
  85
  86 /* crypto API for zcache  */
  87 #define ZCACHE_COMP_NAME_SZ CRYPTO_MAX_ALG_NAME
  88 static char zcache_comp_name[ZCACHE_COMP_NAME_SZ];
  89 static struct crypto_comp * __percpu *zcache_comp_pcpu_tfms;
  90
  91 enum comp_op {
  92         ZCACHE_COMPOP_COMPRESS,
  93         ZCACHE_COMPOP_DECOMPRESS
  94 };
  95
  96 static inline int zcache_comp_op(enum comp_op op,
  97                                 const u8 *src, unsigned int slen,
  98                                 u8 *dst, unsigned int *dlen)
  99 {
 100         struct crypto_comp *tfm;
 101         int ret;
 102
 103         BUG_ON(!zcache_comp_pcpu_tfms);
 104         tfm = *per_cpu_ptr(zcache_comp_pcpu_tfms, get_cpu());
 105         BUG_ON(!tfm);
 106         switch (op) {
 107         case ZCACHE_COMPOP_COMPRESS:
 108                 ret = crypto_comp_compress(tfm, src, slen, dst, dlen);
 109                 break;
 110         case ZCACHE_COMPOP_DECOMPRESS:
 111                 ret = crypto_comp_decompress(tfm, src, slen, dst, dlen);
 112                 break;
 113         }
 114         put_cpu();
 115         return ret;
 116 }
 117
 118 /**********
 119  * Compression buddies ("zbud") provides for packing two (or, possibly
 120  * in the future, more) compressed ephemeral pages into a single "raw"
 121  * (physical) page and tracking them with data structures so that
 122  * the raw pages can be easily reclaimed.
 123  *
 124  * A zbud page ("zbpg") is an aligned page containing a list_head,
 125  * a lock, and two "zbud headers".  The remainder of the physical
 126  * page is divided up into aligned 64-byte "chunks" which contain
 127  * the compressed data for zero, one, or two zbuds.  Each zbpg
 128  * resides on: (1) an "unused list" if it has no zbuds; (2) a
 129  * "buddied" list if it is fully populated  with two zbuds; or
 130  * (3) one of PAGE_SIZE/64 "unbuddied" lists indexed by how many chunks
 131  * the one unbuddied zbud uses.  The data inside a zbpg cannot be
 132  * read or written unless the zbpg's lock is held.
 133  */
 134
 135 #define ZBH_SENTINEL  0x43214321
 136 #define ZBPG_SENTINEL  0xdeadbeef
 137
 138 #define ZBUD_MAX_BUDS 2
 139
 140 struct zbud_hdr {
 141         uint16_t client_id;
 142         uint16_t pool_id;
 143         struct tmem_oid oid;
 144         uint32_t index;
 145         uint16_t size; /* compressed size in bytes, zero means unused */
 146         DECL_SENTINEL
 147 };
 148
 149 struct zbud_page {
 150         struct list_head bud_list;
 151         spinlock_t lock;
 152         struct zbud_hdr buddy[ZBUD_MAX_BUDS];
 153         DECL_SENTINEL
 154         /* followed by NUM_CHUNK aligned CHUNK_SIZE-byte chunks */
 155 };
 156
 157 #define CHUNK_SHIFT     6
 158 #define CHUNK_SIZE      (1 << CHUNK_SHIFT)
 159 #define CHUNK_MASK      (~(CHUNK_SIZE-1))
 160 #define NCHUNKS         (((PAGE_SIZE - sizeof(struct zbud_page)) & \
 161                                 CHUNK_MASK) >> CHUNK_SHIFT)
 162 #define MAX_CHUNK       (NCHUNKS-1)
 163
 164 static struct {
 165         struct list_head list;
 166         unsigned count;
 167 } zbud_unbuddied[NCHUNKS];
 168 /* list N contains pages with N chunks USED and NCHUNKS-N unused */
 169 /* element 0 is never used but optimizing that isn't worth it */
 170 static unsigned long zbud_cumul_chunk_counts[NCHUNKS];
 171
 172 struct list_head zbud_buddied_list;
 173 static unsigned long zcache_zbud_buddied_count;
 174
 175 /* protects the buddied list and all unbuddied lists */
 176 static DEFINE_SPINLOCK(zbud_budlists_spinlock);
 177
 178 static LIST_HEAD(zbpg_unused_list);
 179 static unsigned long zcache_zbpg_unused_list_count;
 180
 181 /* protects the unused page list */
 182 static DEFINE_SPINLOCK(zbpg_unused_list_spinlock);
 183
 184 static atomic_t zcache_zbud_curr_raw_pages;
 185 static atomic_t zcache_zbud_curr_zpages;
 186 static unsigned long zcache_zbud_curr_zbytes;
 187 static unsigned long zcache_zbud_cumul_zpages;
 188 static unsigned long zcache_zbud_cumul_zbytes;
 189 static unsigned long zcache_compress_poor;
 190 static unsigned long zcache_mean_compress_poor;
 191
 192 /* forward references */
 193 static void *zcache_get_free_page(void);
 194 static void zcache_free_page(void *p);
 195
 196 /*
 197  * zbud helper functions
 198  */
 199
 200 static inline unsigned zbud_max_buddy_size(void)
 201 {
 202         return MAX_CHUNK << CHUNK_SHIFT;
 203 }
 204
 205 static inline unsigned zbud_size_to_chunks(unsigned size)
 206 {
 207         BUG_ON(size == 0 || size > zbud_max_buddy_size());
 208         return (size + CHUNK_SIZE - 1) >> CHUNK_SHIFT;
 209 }
 210
 211 static inline int zbud_budnum(struct zbud_hdr *zh)
 212 {
 213         unsigned offset = (unsigned long)zh & (PAGE_SIZE - 1);
 214         struct zbud_page *zbpg = NULL;
 215         unsigned budnum = -1U;
 216         int i;
 217
 218         for (i = 0; i < ZBUD_MAX_BUDS; i++)
 219                 if (offset == offsetof(typeof(*zbpg), buddy[i])) {
 220                         budnum = i;
 221                         break;
 222                 }
 223         BUG_ON(budnum == -1U);
 224         return budnum;
 225 }
 226
 227 static char *zbud_data(struct zbud_hdr *zh, unsigned size)
 228 {
 229         struct zbud_page *zbpg;
 230         char *p;
 231         unsigned budnum;
 232
 233         ASSERT_SENTINEL(zh, ZBH);
 234         budnum = zbud_budnum(zh);
 235         BUG_ON(size == 0 || size > zbud_max_buddy_size());
 236         zbpg = container_of(zh, struct zbud_page, buddy[budnum]);
 237         ASSERT_SPINLOCK(&zbpg->lock);
 238         p = (char *)zbpg;
 239         if (budnum == 0)
 240                 p += ((sizeof(struct zbud_page) + CHUNK_SIZE - 1) &
 241                                                         CHUNK_MASK);
 242         else if (budnum == 1)
 243                 p += PAGE_SIZE - ((size + CHUNK_SIZE - 1) & CHUNK_MASK);
 244         return p;
 245 }
 246
 247 /*
 248  * zbud raw page management
 249  */
 250
 251 static struct zbud_page *zbud_alloc_raw_page(void)
 252 {
 253         struct zbud_page *zbpg = NULL;
 254         struct zbud_hdr *zh0, *zh1;
 255         bool recycled = 0;
 256
 257         /* if any pages on the zbpg list, use one */
 258         spin_lock(&zbpg_unused_list_spinlock);
 259         if (!list_empty(&zbpg_unused_list)) {
 260                 zbpg = list_first_entry(&zbpg_unused_list,
 261                                 struct zbud_page, bud_list);
 262                 list_del_init(&zbpg->bud_list);
 263                 zcache_zbpg_unused_list_count--;
 264                 recycled = 1;
 265         }
 266         spin_unlock(&zbpg_unused_list_spinlock);
 267         if (zbpg == NULL)
 268                 /* none on zbpg list, try to get a kernel page */
 269                 zbpg = zcache_get_free_page();
 270         if (likely(zbpg != NULL)) {
 271                 INIT_LIST_HEAD(&zbpg->bud_list);
 272                 zh0 = &zbpg->buddy[0]; zh1 = &zbpg->buddy[1];
 273                 spin_lock_init(&zbpg->lock);
 274                 if (recycled) {
 275                         ASSERT_INVERTED_SENTINEL(zbpg, ZBPG);
 276                         SET_SENTINEL(zbpg, ZBPG);
 277                         BUG_ON(zh0->size != 0 || tmem_oid_valid(&zh0->oid));
 278                         BUG_ON(zh1->size != 0 || tmem_oid_valid(&zh1->oid));
 279                 } else {
 280                         atomic_inc(&zcache_zbud_curr_raw_pages);
 281                         INIT_LIST_HEAD(&zbpg->bud_list);
 282                         SET_SENTINEL(zbpg, ZBPG);
 283                         zh0->size = 0; zh1->size = 0;
 284                         tmem_oid_set_invalid(&zh0->oid);
 285                         tmem_oid_set_invalid(&zh1->oid);
 286                 }
 287         }
 288         return zbpg;
 289 }
 290
 291 static void zbud_free_raw_page(struct zbud_page *zbpg)
 292 {
 293         struct zbud_hdr *zh0 = &zbpg->buddy[0], *zh1 = &zbpg->buddy[1];
 294
 295         ASSERT_SENTINEL(zbpg, ZBPG);
 296         BUG_ON(!list_empty(&zbpg->bud_list));
 297         ASSERT_SPINLOCK(&zbpg->lock);
 298         BUG_ON(zh0->size != 0 || tmem_oid_valid(&zh0->oid));
 299         BUG_ON(zh1->size != 0 || tmem_oid_valid(&zh1->oid));
 300         INVERT_SENTINEL(zbpg, ZBPG);
 301         spin_unlock(&zbpg->lock);
 302         spin_lock(&zbpg_unused_list_spinlock);
 303         list_add(&zbpg->bud_list, &zbpg_unused_list);
 304         zcache_zbpg_unused_list_count++;
 305         spin_unlock(&zbpg_unused_list_spinlock);
 306 }
 307
 308 /*
 309  * core zbud handling routines
 310  */
 311
 312 static unsigned zbud_free(struct zbud_hdr *zh)
 313 {
 314         unsigned size;
 315
 316         ASSERT_SENTINEL(zh, ZBH);
 317         BUG_ON(!tmem_oid_valid(&zh->oid));
 318         size = zh->size;
 319         BUG_ON(zh->size == 0 || zh->size > zbud_max_buddy_size());
 320         zh->size = 0;
 321         tmem_oid_set_invalid(&zh->oid);
 322         INVERT_SENTINEL(zh, ZBH);
 323         zcache_zbud_curr_zbytes -= size;
 324         atomic_dec(&zcache_zbud_curr_zpages);
 325         return size;
 326 }
 327
 328 static void zbud_free_and_delist(struct zbud_hdr *zh)
 329 {
 330         unsigned chunks;
 331         struct zbud_hdr *zh_other;
 332         unsigned budnum = zbud_budnum(zh), size;
 333         struct zbud_page *zbpg =
 334                 container_of(zh, struct zbud_page, buddy[budnum]);
 335
 336         spin_lock(&zbud_budlists_spinlock);
 337         spin_lock(&zbpg->lock);
 338         if (list_empty(&zbpg->bud_list)) {
 339                 /* ignore zombie page... see zbud_evict_pages() */
 340                 spin_unlock(&zbpg->lock);
 341                 spin_unlock(&zbud_budlists_spinlock);
 342                 return;
 343         }
 344         size = zbud_free(zh);
 345         ASSERT_SPINLOCK(&zbpg->lock);
 346         zh_other = &zbpg->buddy[(budnum == 0) ? 1 : 0];
 347         if (zh_other->size == 0) { /* was unbuddied: unlist and free */
 348                 chunks = zbud_size_to_chunks(size) ;
 349                 BUG_ON(list_empty(&zbud_unbuddied[chunks].list));
 350                 list_del_init(&zbpg->bud_list);
 351                 zbud_unbuddied[chunks].count--;
 352                 spin_unlock(&zbud_budlists_spinlock);
 353                 zbud_free_raw_page(zbpg);
 354         } else { /* was buddied: move remaining buddy to unbuddied list */
 355                 chunks = zbud_size_to_chunks(zh_other->size) ;
 356                 list_del_init(&zbpg->bud_list);
 357                 zcache_zbud_buddied_count--;
 358                 list_add_tail(&zbpg->bud_list, &zbud_unbuddied[chunks].list);
 359                 zbud_unbuddied[chunks].count++;
 360                 spin_unlock(&zbud_budlists_spinlock);
 361                 spin_unlock(&zbpg->lock);
 362         }
 363 }
 364
 365 static struct zbud_hdr *zbud_create(uint16_t client_id, uint16_t pool_id,
 366                                         struct tmem_oid *oid,
 367                                         uint32_t index, struct page *page,
 368                                         void *cdata, unsigned size)
 369 {
 370         struct zbud_hdr *zh0, *zh1, *zh = NULL;
 371         struct zbud_page *zbpg = NULL, *ztmp;
 372         unsigned nchunks;
 373         char *to;
 374         int i, found_good_buddy = 0;
 375
 376         nchunks = zbud_size_to_chunks(size) ;
 377         for (i = MAX_CHUNK - nchunks + 1; i > 0; i--) {
 378                 spin_lock(&zbud_budlists_spinlock);
 379                 if (!list_empty(&zbud_unbuddied[i].list)) {
 380                         list_for_each_entry_safe(zbpg, ztmp,
 381                                     &zbud_unbuddied[i].list, bud_list) {
 382                                 if (spin_trylock(&zbpg->lock)) {
 383                                         found_good_buddy = i;
 384                                         goto found_unbuddied;
 385                                 }
 386                         }
 387                 }
 388                 spin_unlock(&zbud_budlists_spinlock);
 389         }
 390         /* didn't find a good buddy, try allocating a new page */
 391         zbpg = zbud_alloc_raw_page();
 392         if (unlikely(zbpg == NULL))
 393                 goto out;
 394         /* ok, have a page, now compress the data before taking locks */
 395         spin_lock(&zbud_budlists_spinlock);
 396         spin_lock(&zbpg->lock);
 397         list_add_tail(&zbpg->bud_list, &zbud_unbuddied[nchunks].list);
 398         zbud_unbuddied[nchunks].count++;
 399         zh = &zbpg->buddy[0];
 400         goto init_zh;
 401
 402 found_unbuddied:
 403         ASSERT_SPINLOCK(&zbpg->lock);
 404         zh0 = &zbpg->buddy[0]; zh1 = &zbpg->buddy[1];
 405         BUG_ON(!((zh0->size == 0) ^ (zh1->size == 0)));
 406         if (zh0->size != 0) { /* buddy0 in use, buddy1 is vacant */
 407                 ASSERT_SENTINEL(zh0, ZBH);
 408                 zh = zh1;
 409         } else if (zh1->size != 0) { /* buddy1 in use, buddy0 is vacant */
 410                 ASSERT_SENTINEL(zh1, ZBH);
 411                 zh = zh0;
 412         } else
 413                 BUG();
 414         list_del_init(&zbpg->bud_list);
 415         zbud_unbuddied[found_good_buddy].count--;
 416         list_add_tail(&zbpg->bud_list, &zbud_buddied_list);
 417         zcache_zbud_buddied_count++;
 418
 419 init_zh:
 420         SET_SENTINEL(zh, ZBH);
 421         zh->size = size;
 422         zh->index = index;
 423         zh->oid = *oid;
 424         zh->pool_id = pool_id;
 425         zh->client_id = client_id;
 426         to = zbud_data(zh, size);
 427         memcpy(to, cdata, size);
 428         spin_unlock(&zbpg->lock);
 429         spin_unlock(&zbud_budlists_spinlock);
 430
 431         zbud_cumul_chunk_counts[nchunks]++;
 432         atomic_inc(&zcache_zbud_curr_zpages);
 433         zcache_zbud_cumul_zpages++;
 434         zcache_zbud_curr_zbytes += size;
 435         zcache_zbud_cumul_zbytes += size;
 436 out:
 437         return zh;
 438 }
 439
 440 static int zbud_decompress(struct page *page, struct zbud_hdr *zh)
 441 {
 442         struct zbud_page *zbpg;
 443         unsigned budnum = zbud_budnum(zh);
 444         unsigned int out_len = PAGE_SIZE;
 445         char *to_va, *from_va;
 446         unsigned size;
 447         int ret = 0;
 448
 449         zbpg = container_of(zh, struct zbud_page, buddy[budnum]);
 450         spin_lock(&zbpg->lock);
 451         if (list_empty(&zbpg->bud_list)) {
 452                 /* ignore zombie page... see zbud_evict_pages() */
 453                 ret = -EINVAL;
 454                 goto out;
 455         }
 456         ASSERT_SENTINEL(zh, ZBH);
 457         BUG_ON(zh->size == 0 || zh->size > zbud_max_buddy_size());
 458         to_va = kmap_atomic(page);
 459         size = zh->size;
 460         from_va = zbud_data(zh, size);
 461         ret = zcache_comp_op(ZCACHE_COMPOP_DECOMPRESS, from_va, size,
 462                                 to_va, &out_len);
 463         BUG_ON(ret);
 464         BUG_ON(out_len != PAGE_SIZE);
 465         kunmap_atomic(to_va);
 466 out:
 467         spin_unlock(&zbpg->lock);
 468         return ret;
 469 }
 470
 471 /*
 472  * The following routines handle shrinking of ephemeral pages by evicting
 473  * pages "least valuable" first.
 474  */
 475
 476 static unsigned long zcache_evicted_raw_pages;
 477 static unsigned long zcache_evicted_buddied_pages;
 478 static unsigned long zcache_evicted_unbuddied_pages;
 479
 480 static struct tmem_pool *zcache_get_pool_by_id(uint16_t cli_id,
 481                                                 uint16_t poolid);
 482 static void zcache_put_pool(struct tmem_pool *pool);
 483
 484 /*
 485  * Flush and free all zbuds in a zbpg, then free the pageframe
 486  */
 487 static void zbud_evict_zbpg(struct zbud_page *zbpg)
 488 {
 489         struct zbud_hdr *zh;
 490         int i, j;
 491         uint32_t pool_id[ZBUD_MAX_BUDS], client_id[ZBUD_MAX_BUDS];
 492         uint32_t index[ZBUD_MAX_BUDS];
 493         struct tmem_oid oid[ZBUD_MAX_BUDS];
 494         struct tmem_pool *pool;
 495
 496         ASSERT_SPINLOCK(&zbpg->lock);
 497         BUG_ON(!list_empty(&zbpg->bud_list));
 498         for (i = 0, j = 0; i < ZBUD_MAX_BUDS; i++) {
 499                 zh = &zbpg->buddy[i];
 500                 if (zh->size) {
 501                         client_id[j] = zh->client_id;
 502                         pool_id[j] = zh->pool_id;
 503                         oid[j] = zh->oid;
 504                         index[j] = zh->index;
 505                         j++;
 506                         zbud_free(zh);
 507                 }
 508         }
 509         spin_unlock(&zbpg->lock);
 510         for (i = 0; i < j; i++) {
 511                 pool = zcache_get_pool_by_id(client_id[i], pool_id[i]);
 512                 if (pool != NULL) {
 513                         tmem_flush_page(pool, &oid[i], index[i]);
 514                         zcache_put_pool(pool);
 515                 }
 516         }
 517         ASSERT_SENTINEL(zbpg, ZBPG);
 518         spin_lock(&zbpg->lock);
 519         zbud_free_raw_page(zbpg);
 520 }
 521
 522 /*
 523  * Free nr pages.  This code is funky because we want to hold the locks
 524  * protecting various lists for as short a time as possible, and in some
 525  * circumstances the list may change asynchronously when the list lock is
 526  * not held.  In some cases we also trylock not only to avoid waiting on a
 527  * page in use by another cpu, but also to avoid potential deadlock due to
 528  * lock inversion.
 529  */
 530 static void zbud_evict_pages(int nr)
 531 {
 532         struct zbud_page *zbpg;
 533         int i;
 534
 535         /* first try freeing any pages on unused list */
 536 retry_unused_list:
 537         spin_lock_bh(&zbpg_unused_list_spinlock);
 538         if (!list_empty(&zbpg_unused_list)) {
 539                 /* can't walk list here, since it may change when unlocked */
 540                 zbpg = list_first_entry(&zbpg_unused_list,
 541                                 struct zbud_page, bud_list);
 542                 list_del_init(&zbpg->bud_list);
 543                 zcache_zbpg_unused_list_count--;
 544                 atomic_dec(&zcache_zbud_curr_raw_pages);
 545                 spin_unlock_bh(&zbpg_unused_list_spinlock);
 546                 zcache_free_page(zbpg);
 547                 zcache_evicted_raw_pages++;
 548                 if (--nr <= 0)
 549                         goto out;
 550                 goto retry_unused_list;
 551         }
 552         spin_unlock_bh(&zbpg_unused_list_spinlock);
 553
 554         /* now try freeing unbuddied pages, starting with least space avail */
 555         for (i = 0; i < MAX_CHUNK; i++) {
 556 retry_unbud_list_i:
 557                 spin_lock_bh(&zbud_budlists_spinlock);
 558                 if (list_empty(&zbud_unbuddied[i].list)) {
 559                         spin_unlock_bh(&zbud_budlists_spinlock);
 560                         continue;
 561                 }
 562                 list_for_each_entry(zbpg, &zbud_unbuddied[i].list, bud_list) {
 563                         if (unlikely(!spin_trylock(&zbpg->lock)))
 564                                 continue;
 565                         list_del_init(&zbpg->bud_list);
 566                         zbud_unbuddied[i].count--;
 567                         spin_unlock(&zbud_budlists_spinlock);
 568                         zcache_evicted_unbuddied_pages++;
 569                         /* want budlists unlocked when doing zbpg eviction */
 570                         zbud_evict_zbpg(zbpg);
 571                         local_bh_enable();
 572                         if (--nr <= 0)
 573                                 goto out;
 574                         goto retry_unbud_list_i;
 575                 }
 576                 spin_unlock_bh(&zbud_budlists_spinlock);
 577         }
 578
 579         /* as a last resort, free buddied pages */
 580 retry_bud_list:
 581         spin_lock_bh(&zbud_budlists_spinlock);
 582         if (list_empty(&zbud_buddied_list)) {
 583                 spin_unlock_bh(&zbud_budlists_spinlock);
 584                 goto out;
 585         }
 586         list_for_each_entry(zbpg, &zbud_buddied_list, bud_list) {
 587                 if (unlikely(!spin_trylock(&zbpg->lock)))
 588                         continue;
 589                 list_del_init(&zbpg->bud_list);
 590                 zcache_zbud_buddied_count--;
 591                 spin_unlock(&zbud_budlists_spinlock);
 592                 zcache_evicted_buddied_pages++;
 593                 /* want budlists unlocked when doing zbpg eviction */
 594                 zbud_evict_zbpg(zbpg);
 595                 local_bh_enable();
 596                 if (--nr <= 0)
 597                         goto out;
 598                 goto retry_bud_list;
 599         }
 600         spin_unlock_bh(&zbud_budlists_spinlock);
 601 out:
 602         return;
 603 }
 604
 605 static void zbud_init(void)
 606 {
 607         int i;
 608
 609         INIT_LIST_HEAD(&zbud_buddied_list);
 610         zcache_zbud_buddied_count = 0;
 611         for (i = 0; i < NCHUNKS; i++) {
 612                 INIT_LIST_HEAD(&zbud_unbuddied[i].list);
 613                 zbud_unbuddied[i].count = 0;
 614         }
 615 }
 616
 617 #ifdef CONFIG_SYSFS
 618 /*
 619  * These sysfs routines show a nice distribution of how many zbpg's are
 620  * currently (and have ever been placed) in each unbuddied list.  It's fun
 621  * to watch but can probably go away before final merge.
 622  */
 623 static int zbud_show_unbuddied_list_counts(char *buf)
 624 {
 625         int i;
 626         char *p = buf;
 627
 628         for (i = 0; i < NCHUNKS; i++)
 629                 p += sprintf(p, "%u ", zbud_unbuddied[i].count);
 630         return p - buf;
 631 }
 632
 633 static int zbud_show_cumul_chunk_counts(char *buf)
 634 {
 635         unsigned long i, chunks = 0, total_chunks = 0, sum_total_chunks = 0;
 636         unsigned long total_chunks_lte_21 = 0, total_chunks_lte_32 = 0;
 637         unsigned long total_chunks_lte_42 = 0;
 638         char *p = buf;
 639
 640         for (i = 0; i < NCHUNKS; i++) {
 641                 p += sprintf(p, "%lu ", zbud_cumul_chunk_counts[i]);
 642                 chunks += zbud_cumul_chunk_counts[i];
 643                 total_chunks += zbud_cumul_chunk_counts[i];
 644                 sum_total_chunks += i * zbud_cumul_chunk_counts[i];
 645                 if (i == 21)
 646                         total_chunks_lte_21 = total_chunks;
 647                 if (i == 32)
 648                         total_chunks_lte_32 = total_chunks;
 649                 if (i == 42)
 650                         total_chunks_lte_42 = total_chunks;
 651         }
 652         p += sprintf(p, "<=21:%lu <=32:%lu <=42:%lu, mean:%lu\n",
 653                 total_chunks_lte_21, total_chunks_lte_32, total_chunks_lte_42,
 654                 chunks == 0 ? 0 : sum_total_chunks / chunks);
 655         return p - buf;
 656 }
 657 #endif
 658
 659 /**********
 660  * This "zv" PAM implementation combines the slab-based zsmalloc
 661  * with the crypto compression API to maximize the amount of data that can
 662  * be packed into a physical page.
 663  *
 664  * Zv represents a PAM page with the index and object (plus a "size" value
 665  * necessary for decompression) immediately preceding the compressed data.
 666  */
 667
 668 #define ZVH_SENTINEL  0x43214321
 669
 670 struct zv_hdr {
 671         uint32_t pool_id;
 672         struct tmem_oid oid;
 673         uint32_t index;
 674         size_t size;
 675         DECL_SENTINEL
 676 };
 677
 678 /* rudimentary policy limits */
 679 /* total number of persistent pages may not exceed this percentage */
 680 static unsigned int zv_page_count_policy_percent = 75;
 681 /*
 682  * byte count defining poor compression; pages with greater zsize will be
 683  * rejected
 684  */
 685 static unsigned int zv_max_zsize = (PAGE_SIZE / 8) * 7;
 686 /*
 687  * byte count defining poor *mean* compression; pages with greater zsize
 688  * will be rejected until sufficient better-compressed pages are accepted
 689  * driving the mean below this threshold
 690  */
 691 static unsigned int zv_max_mean_zsize = (PAGE_SIZE / 8) * 5;
 692
 693 static atomic_t zv_curr_dist_counts[NCHUNKS];
 694 static atomic_t zv_cumul_dist_counts[NCHUNKS];
 695
 696 static struct zv_hdr *zv_create(struct zs_pool *pool, uint32_t pool_id,
 697                                 struct tmem_oid *oid, uint32_t index,
 698                                 void *cdata, unsigned clen)
 699 {
 700         struct zv_hdr *zv;
 701         u32 size = clen + sizeof(struct zv_hdr);
 702         int chunks = (size + (CHUNK_SIZE - 1)) >> CHUNK_SHIFT;
 703         void *handle = NULL;
 704
 705         BUG_ON(!irqs_disabled());
 706         BUG_ON(chunks >= NCHUNKS);
 707         handle = zs_malloc(pool, size);
 708         if (!handle)
 709                 goto out;
 710         atomic_inc(&zv_curr_dist_counts[chunks]);
 711         atomic_inc(&zv_cumul_dist_counts[chunks]);
 712         zv = zs_map_object(pool, handle);
 713         zv->index = index;
 714         zv->oid = *oid;
 715         zv->pool_id = pool_id;
 716         zv->size = clen;
 717         SET_SENTINEL(zv, ZVH);
 718         memcpy((char *)zv + sizeof(struct zv_hdr), cdata, clen);
 719         zs_unmap_object(pool, handle);
 720 out:
 721         return handle;
 722 }
 723
 724 static void zv_free(struct zs_pool *pool, void *handle)
 725 {
 726         unsigned long flags;
 727         struct zv_hdr *zv;
 728         uint16_t size;
 729         int chunks;
 730
 731         zv = zs_map_object(pool, handle);
 732         ASSERT_SENTINEL(zv, ZVH);
 733         size = zv->size + sizeof(struct zv_hdr);
 734         INVERT_SENTINEL(zv, ZVH);
 735         zs_unmap_object(pool, handle);
 736
 737         chunks = (size + (CHUNK_SIZE - 1)) >> CHUNK_SHIFT;
 738         BUG_ON(chunks >= NCHUNKS);
 739         atomic_dec(&zv_curr_dist_counts[chunks]);
 740
 741         local_irq_save(flags);
 742         zs_free(pool, handle);
 743         local_irq_restore(flags);
 744 }
 745
 746 static void zv_decompress(struct page *page, void *handle)
 747 {
 748         unsigned int clen = PAGE_SIZE;
 749         char *to_va;
 750         int ret;
 751         struct zv_hdr *zv;
 752
 753         zv = zs_map_object(zcache_host.zspool, handle);
 754         BUG_ON(zv->size == 0);
 755         ASSERT_SENTINEL(zv, ZVH);
 756         to_va = kmap_atomic(page);
 757         ret = zcache_comp_op(ZCACHE_COMPOP_DECOMPRESS, (char *)zv + sizeof(*zv),
 758                                 zv->size, to_va, &clen);
 759         kunmap_atomic(to_va);
 760         zs_unmap_object(zcache_host.zspool, handle);
 761         BUG_ON(ret);
 762         BUG_ON(clen != PAGE_SIZE);
 763 }
 764
 765 #ifdef CONFIG_SYSFS
 766 /*
 767  * show a distribution of compression stats for zv pages.
 768  */
 769
 770 static int zv_curr_dist_counts_show(char *buf)
 771 {
 772         unsigned long i, n, chunks = 0, sum_total_chunks = 0;
 773         char *p = buf;
 774
 775         for (i = 0; i < NCHUNKS; i++) {
 776                 n = atomic_read(&zv_curr_dist_counts[i]);
 777                 p += sprintf(p, "%lu ", n);
 778                 chunks += n;
 779                 sum_total_chunks += i * n;
 780         }
 781         p += sprintf(p, "mean:%lu\n",
 782                 chunks == 0 ? 0 : sum_total_chunks / chunks);
 783         return p - buf;
 784 }
 785
 786 static int zv_cumul_dist_counts_show(char *buf)
 787 {
 788         unsigned long i, n, chunks = 0, sum_total_chunks = 0;
 789         char *p = buf;
 790
 791         for (i = 0; i < NCHUNKS; i++) {
 792                 n = atomic_read(&zv_cumul_dist_counts[i]);
 793                 p += sprintf(p, "%lu ", n);
 794                 chunks += n;
 795                 sum_total_chunks += i * n;
 796         }
 797         p += sprintf(p, "mean:%lu\n",
 798                 chunks == 0 ? 0 : sum_total_chunks / chunks);
 799         return p - buf;
 800 }
 801
 802 /*
 803  * setting zv_max_zsize via sysfs causes all persistent (e.g. swap)
 804  * pages that don't compress to less than this value (including metadata
 805  * overhead) to be rejected.  We don't allow the value to get too close
 806  * to PAGE_SIZE.
 807  */
 808 static ssize_t zv_max_zsize_show(struct kobject *kobj,
 809                                     struct kobj_attribute *attr,
 810                                     char *buf)
 811 {
 812         return sprintf(buf, "%u\n", zv_max_zsize);
 813 }
 814
 815 static ssize_t zv_max_zsize_store(struct kobject *kobj,
 816                                     struct kobj_attribute *attr,
 817                                     const char *buf, size_t count)
 818 {
 819         unsigned long val;
 820         int err;
 821
 822         if (!capable(CAP_SYS_ADMIN))
 823                 return -EPERM;
 824
 825         err = kstrtoul(buf, 10, &val);
 826         if (err || (val == 0) || (val > (PAGE_SIZE / 8) * 7))
 827                 return -EINVAL;
 828         zv_max_zsize = val;
 829         return count;
 830 }
 831
 832 /*
 833  * setting zv_max_mean_zsize via sysfs causes all persistent (e.g. swap)
 834  * pages that don't compress to less than this value (including metadata
 835  * overhead) to be rejected UNLESS the mean compression is also smaller
 836  * than this value.  In other words, we are load-balancing-by-zsize the
 837  * accepted pages.  Again, we don't allow the value to get too close
 838  * to PAGE_SIZE.
 839  */
 840 static ssize_t zv_max_mean_zsize_show(struct kobject *kobj,
 841                                     struct kobj_attribute *attr,
 842                                     char *buf)
 843 {
 844         return sprintf(buf, "%u\n", zv_max_mean_zsize);
 845 }
 846
 847 static ssize_t zv_max_mean_zsize_store(struct kobject *kobj,
 848                                     struct kobj_attribute *attr,
 849                                     const char *buf, size_t count)
 850 {
 851         unsigned long val;
 852         int err;
 853
 854         if (!capable(CAP_SYS_ADMIN))
 855                 return -EPERM;
 856
 857         err = kstrtoul(buf, 10, &val);
 858         if (err || (val == 0) || (val > (PAGE_SIZE / 8) * 7))
 859                 return -EINVAL;
 860         zv_max_mean_zsize = val;
 861         return count;
 862 }
 863
 864 /*
 865  * setting zv_page_count_policy_percent via sysfs sets an upper bound of
 866  * persistent (e.g. swap) pages that will be retained according to:
 867  *     (zv_page_count_policy_percent * totalram_pages) / 100)
 868  * when that limit is reached, further puts will be rejected (until
 869  * some pages have been flushed).  Note that, due to compression,
 870  * this number may exceed 100; it defaults to 75 and we set an
 871  * arbitary limit of 150.  A poor choice will almost certainly result
 872  * in OOM's, so this value should only be changed prudently.
 873  */
 874 static ssize_t zv_page_count_policy_percent_show(struct kobject *kobj,
 875                                                  struct kobj_attribute *attr,
 876                                                  char *buf)
 877 {
 878         return sprintf(buf, "%u\n", zv_page_count_policy_percent);
 879 }
 880
 881 static ssize_t zv_page_count_policy_percent_store(struct kobject *kobj,
 882                                                   struct kobj_attribute *attr,
 883                                                   const char *buf, size_t count)
 884 {
 885         unsigned long val;
 886         int err;
 887
 888         if (!capable(CAP_SYS_ADMIN))
 889                 return -EPERM;
 890
 891         err = kstrtoul(buf, 10, &val);
 892         if (err || (val == 0) || (val > 150))
 893                 return -EINVAL;
 894         zv_page_count_policy_percent = val;
 895         return count;
 896 }
 897
 898 static struct kobj_attribute zcache_zv_max_zsize_attr = {
 899                 .attr = { .name = "zv_max_zsize", .mode = 0644 },
 900                 .show = zv_max_zsize_show,
 901                 .store = zv_max_zsize_store,
 902 };
 903
 904 static struct kobj_attribute zcache_zv_max_mean_zsize_attr = {
 905                 .attr = { .name = "zv_max_mean_zsize", .mode = 0644 },
 906                 .show = zv_max_mean_zsize_show,
 907                 .store = zv_max_mean_zsize_store,
 908 };
 909
 910 static struct kobj_attribute zcache_zv_page_count_policy_percent_attr = {
 911                 .attr = { .name = "zv_page_count_policy_percent",
 912                           .mode = 0644 },
 913                 .show = zv_page_count_policy_percent_show,
 914                 .store = zv_page_count_policy_percent_store,
 915 };
 916 #endif
 917
 918 /*
 919  * zcache core code starts here
 920  */
 921
 922 /* useful stats not collected by cleancache or frontswap */
 923 static unsigned long zcache_flush_total;
 924 static unsigned long zcache_flush_found;
 925 static unsigned long zcache_flobj_total;
 926 static unsigned long zcache_flobj_found;
 927 static unsigned long zcache_failed_eph_puts;
 928 static unsigned long zcache_failed_pers_puts;
 929
 930 /*
 931  * Tmem operations assume the poolid implies the invoking client.
 932  * Zcache only has one client (the kernel itself): LOCAL_CLIENT.
 933  * RAMster has each client numbered by cluster node, and a KVM version
 934  * of zcache would have one client per guest and each client might
 935  * have a poolid==N.
 936  */
 937 static struct tmem_pool *zcache_get_pool_by_id(uint16_t cli_id, uint16_t poolid)
 938 {
 939         struct tmem_pool *pool = NULL;
 940         struct zcache_client *cli = NULL;
 941
 942         if (cli_id == LOCAL_CLIENT)
 943                 cli = &zcache_host;
 944         else {
 945                 if (cli_id >= MAX_CLIENTS)
 946                         goto out;
 947                 cli = &zcache_clients[cli_id];
 948                 if (cli == NULL)
 949                         goto out;
 950                 atomic_inc(&cli->refcount);
 951         }
 952         if (poolid < MAX_POOLS_PER_CLIENT) {
 953                 pool = cli->tmem_pools[poolid];
 954                 if (pool != NULL)
 955                         atomic_inc(&pool->refcount);
 956         }
 957 out:
 958         return pool;
 959 }
 960
 961 static void zcache_put_pool(struct tmem_pool *pool)
 962 {
 963         struct zcache_client *cli = NULL;
 964
 965         if (pool == NULL)
 966                 BUG();
 967         cli = pool->client;
 968         atomic_dec(&pool->refcount);
 969         atomic_dec(&cli->refcount);
 970 }
 971
 972 int zcache_new_client(uint16_t cli_id)
 973 {
 974         struct zcache_client *cli = NULL;
 975         int ret = -1;
 976
 977         if (cli_id == LOCAL_CLIENT)
 978                 cli = &zcache_host;
 979         else if ((unsigned int)cli_id < MAX_CLIENTS)
 980                 cli = &zcache_clients[cli_id];
 981         if (cli == NULL)
 982                 goto out;
 983         if (cli->allocated)
 984                 goto out;
 985         cli->allocated = 1;
 986 #ifdef CONFIG_FRONTSWAP
 987         cli->zspool = zs_create_pool("zcache", ZCACHE_GFP_MASK);
 988         if (cli->zspool == NULL)
 989                 goto out;
 990 #endif
 991         ret = 0;
 992 out:
 993         return ret;
 994 }
 995
 996 /* counters for debugging */
 997 static unsigned long zcache_failed_get_free_pages;
 998 static unsigned long zcache_failed_alloc;
 999 static unsigned long zcache_put_to_flush;
1000
1001 /*
1002  * for now, used named slabs so can easily track usage; later can
1003  * either just use kmalloc, or perhaps add a slab-like allocator
1004  * to more carefully manage total memory utilization
1005  */
1006 static struct kmem_cache *zcache_objnode_cache;
1007 static struct kmem_cache *zcache_obj_cache;
1008 static atomic_t zcache_curr_obj_count = ATOMIC_INIT(0);
1009 static unsigned long zcache_curr_obj_count_max;
1010 static atomic_t zcache_curr_objnode_count = ATOMIC_INIT(0);
1011 static unsigned long zcache_curr_objnode_count_max;
1012
1013 /*
1014  * to avoid memory allocation recursion (e.g. due to direct reclaim), we
1015  * preload all necessary data structures so the hostops callbacks never
1016  * actually do a malloc
1017  */
1018 struct zcache_preload {
1019         void *page;
1020         struct tmem_obj *obj;
1021         int nr;
1022         struct tmem_objnode *objnodes[OBJNODE_TREE_MAX_PATH];
1023 };
1024 static DEFINE_PER_CPU(struct zcache_preload, zcache_preloads) = { 0, };
1025
1026 static int zcache_do_preload(struct tmem_pool *pool)
1027 {
1028         struct zcache_preload *kp;
1029         struct tmem_objnode *objnode;
1030         struct tmem_obj *obj;
1031         void *page;
1032         int ret = -ENOMEM;
1033
1034         if (unlikely(zcache_objnode_cache == NULL))
1035                 goto out;
1036         if (unlikely(zcache_obj_cache == NULL))
1037                 goto out;
1038         preempt_disable();
1039         kp = &__get_cpu_var(zcache_preloads);
1040         while (kp->nr < ARRAY_SIZE(kp->objnodes)) {
1041                 preempt_enable_no_resched();
1042                 objnode = kmem_cache_alloc(zcache_objnode_cache,
1043                                 ZCACHE_GFP_MASK);
1044                 if (unlikely(objnode == NULL)) {
1045                         zcache_failed_alloc++;
1046                         goto out;
1047                 }
1048                 preempt_disable();
1049                 kp = &__get_cpu_var(zcache_preloads);
1050                 if (kp->nr < ARRAY_SIZE(kp->objnodes))
1051                         kp->objnodes[kp->nr++] = objnode;
1052                 else
1053                         kmem_cache_free(zcache_objnode_cache, objnode);
1054         }
1055         preempt_enable_no_resched();
1056         obj = kmem_cache_alloc(zcache_obj_cache, ZCACHE_GFP_MASK);
1057         if (unlikely(obj == NULL)) {
1058                 zcache_failed_alloc++;
1059                 goto out;
1060         }
1061         page = (void *)__get_free_page(ZCACHE_GFP_MASK);
1062         if (unlikely(page == NULL)) {
1063                 zcache_failed_get_free_pages++;
1064                 kmem_cache_free(zcache_obj_cache, obj);
1065                 goto out;
1066         }
1067         preempt_disable();
1068         kp = &__get_cpu_var(zcache_preloads);
1069         if (kp->obj == NULL)
1070                 kp->obj = obj;
1071         else
1072                 kmem_cache_free(zcache_obj_cache, obj);
1073         if (kp->page == NULL)
1074                 kp->page = page;
1075         else
1076                 free_page((unsigned long)page);
1077         ret = 0;
1078 out:
1079         return ret;
1080 }
1081
1082 static void *zcache_get_free_page(void)
1083 {
1084         struct zcache_preload *kp;
1085         void *page;
1086
1087         kp = &__get_cpu_var(zcache_preloads);
1088         page = kp->page;
1089         BUG_ON(page == NULL);
1090         kp->page = NULL;
1091         return page;
1092 }
1093
1094 static void zcache_free_page(void *p)
1095 {
1096         free_page((unsigned long)p);
1097 }
1098
1099 /*
1100  * zcache implementation for tmem host ops
1101  */
1102
1103 static struct tmem_objnode *zcache_objnode_alloc(struct tmem_pool *pool)
1104 {
1105         struct tmem_objnode *objnode = NULL;
1106         unsigned long count;
1107         struct zcache_preload *kp;
1108
1109         kp = &__get_cpu_var(zcache_preloads);
1110         if (kp->nr <= 0)
1111                 goto out;
1112         objnode = kp->objnodes[kp->nr - 1];
1113         BUG_ON(objnode == NULL);
1114         kp->objnodes[kp->nr - 1] = NULL;
1115         kp->nr--;
1116         count = atomic_inc_return(&zcache_curr_objnode_count);
1117         if (count > zcache_curr_objnode_count_max)
1118                 zcache_curr_objnode_count_max = count;
1119 out:
1120         return objnode;
1121 }
1122
1123 static void zcache_objnode_free(struct tmem_objnode *objnode,
1124                                         struct tmem_pool *pool)
1125 {
1126         atomic_dec(&zcache_curr_objnode_count);
1127         BUG_ON(atomic_read(&zcache_curr_objnode_count) < 0);
1128         kmem_cache_free(zcache_objnode_cache, objnode);
1129 }
1130
1131 static struct tmem_obj *zcache_obj_alloc(struct tmem_pool *pool)
1132 {
1133         struct tmem_obj *obj = NULL;
1134         unsigned long count;
1135         struct zcache_preload *kp;
1136
1137         kp = &__get_cpu_var(zcache_preloads);
1138         obj = kp->obj;
1139         BUG_ON(obj == NULL);
1140         kp->obj = NULL;
1141         count = atomic_inc_return(&zcache_curr_obj_count);
1142         if (count > zcache_curr_obj_count_max)
1143                 zcache_curr_obj_count_max = count;
1144         return obj;
1145 }
1146
1147 static void zcache_obj_free(struct tmem_obj *obj, struct tmem_pool *pool)
1148 {
1149         atomic_dec(&zcache_curr_obj_count);
1150         BUG_ON(atomic_read(&zcache_curr_obj_count) < 0);
1151         kmem_cache_free(zcache_obj_cache, obj);
1152 }
1153
1154 static struct tmem_hostops zcache_hostops = {
1155         .obj_alloc = zcache_obj_alloc,
1156         .obj_free = zcache_obj_free,
1157         .objnode_alloc = zcache_objnode_alloc,
1158         .objnode_free = zcache_objnode_free,
1159 };
1160
1161 /*
1162  * zcache implementations for PAM page descriptor ops
1163  */
1164
1165 static atomic_t zcache_curr_eph_pampd_count = ATOMIC_INIT(0);
1166 static unsigned long zcache_curr_eph_pampd_count_max;
1167 static atomic_t zcache_curr_pers_pampd_count = ATOMIC_INIT(0);
1168 static unsigned long zcache_curr_pers_pampd_count_max;
1169
1170 /* forward reference */
1171 static int zcache_compress(struct page *from, void **out_va, unsigned *out_len);
1172
1173 static void *zcache_pampd_create(char *data, size_t size, bool raw, int eph,
1174                                 struct tmem_pool *pool, struct tmem_oid *oid,
1175                                  uint32_t index)
1176 {
1177         void *pampd = NULL, *cdata;
1178         unsigned clen;
1179         int ret;
1180         unsigned long count;
1181         struct page *page = (struct page *)(data);
1182         struct zcache_client *cli = pool->client;
1183         uint16_t client_id = get_client_id_from_client(cli);
1184         unsigned long zv_mean_zsize;
1185         unsigned long curr_pers_pampd_count;
1186         u64 total_zsize;
1187
1188         if (eph) {
1189                 ret = zcache_compress(page, &cdata, &clen);
1190                 if (ret == 0)
1191                         goto out;
1192                 if (clen == 0 || clen > zbud_max_buddy_size()) {
1193                         zcache_compress_poor++;
1194                         goto out;
1195                 }
1196                 pampd = (void *)zbud_create(client_id, pool->pool_id, oid,
1197                                                 index, page, cdata, clen);
1198                 if (pampd != NULL) {
1199                         count = atomic_inc_return(&zcache_curr_eph_pampd_count);
1200                         if (count > zcache_curr_eph_pampd_count_max)
1201                                 zcache_curr_eph_pampd_count_max = count;
1202                 }
1203         } else {
1204                 curr_pers_pampd_count =
1205                         atomic_read(&zcache_curr_pers_pampd_count);
1206                 if (curr_pers_pampd_count >
1207                     (zv_page_count_policy_percent * totalram_pages) / 100)
1208                         goto out;
1209                 ret = zcache_compress(page, &cdata, &clen);
1210                 if (ret == 0)
1211                         goto out;
1212                 /* reject if compression is too poor */
1213                 if (clen > zv_max_zsize) {
1214                         zcache_compress_poor++;
1215                         goto out;
1216                 }
1217                 /* reject if mean compression is too poor */
1218                 if ((clen > zv_max_mean_zsize) && (curr_pers_pampd_count > 0)) {
1219                         total_zsize = zs_get_total_size_bytes(cli->zspool);
1220                         zv_mean_zsize = div_u64(total_zsize,
1221                                                 curr_pers_pampd_count);
1222                         if (zv_mean_zsize > zv_max_mean_zsize) {
1223                                 zcache_mean_compress_poor++;
1224                                 goto out;
1225                         }
1226                 }
1227                 pampd = (void *)zv_create(cli->zspool, pool->pool_id,
1228                                                 oid, index, cdata, clen);
1229                 if (pampd == NULL)
1230                         goto out;
1231                 count = atomic_inc_return(&zcache_curr_pers_pampd_count);
1232                 if (count > zcache_curr_pers_pampd_count_max)
1233                         zcache_curr_pers_pampd_count_max = count;
1234         }
1235 out:
1236         return pampd;
1237 }
1238
1239 /*
1240  * fill the pageframe corresponding to the struct page with the data
1241  * from the passed pampd
1242  */
1243 static int zcache_pampd_get_data(char *data, size_t *bufsize, bool raw,
1244                                         void *pampd, struct tmem_pool *pool,
1245                                         struct tmem_oid *oid, uint32_t index)
1246 {
1247         int ret = 0;
1248
1249         BUG_ON(is_ephemeral(pool));
1250         zv_decompress((struct page *)(data), pampd);
1251         return ret;
1252 }
1253
1254 /*
1255  * fill the pageframe corresponding to the struct page with the data
1256  * from the passed pampd
1257  */
1258 static int zcache_pampd_get_data_and_free(char *data, size_t *bufsize, bool raw,
1259                                         void *pampd, struct tmem_pool *pool,
1260                                         struct tmem_oid *oid, uint32_t index)
1261 {
1262         int ret = 0;
1263
1264         BUG_ON(!is_ephemeral(pool));
1265         zbud_decompress((struct page *)(data), pampd);
1266         zbud_free_and_delist((struct zbud_hdr *)pampd);
1267         atomic_dec(&zcache_curr_eph_pampd_count);
1268         return ret;
1269 }
1270
1271 /*
1272  * free the pampd and remove it from any zcache lists
1273  * pampd must no longer be pointed to from any tmem data structures!
1274  */
1275 static void zcache_pampd_free(void *pampd, struct tmem_pool *pool,
1276                                 struct tmem_oid *oid, uint32_t index)
1277 {
1278         struct zcache_client *cli = pool->client;
1279
1280         if (is_ephemeral(pool)) {
1281                 zbud_free_and_delist((struct zbud_hdr *)pampd);
1282                 atomic_dec(&zcache_curr_eph_pampd_count);
1283                 BUG_ON(atomic_read(&zcache_curr_eph_pampd_count) < 0);
1284         } else {
1285                 zv_free(cli->zspool, pampd);
1286                 atomic_dec(&zcache_curr_pers_pampd_count);
1287                 BUG_ON(atomic_read(&zcache_curr_pers_pampd_count) < 0);
1288         }
1289 }
1290
1291 static void zcache_pampd_free_obj(struct tmem_pool *pool, struct tmem_obj *obj)
1292 {
1293 }
1294
1295 static void zcache_pampd_new_obj(struct tmem_obj *obj)
1296 {
1297 }
1298
1299 static int zcache_pampd_replace_in_obj(void *pampd, struct tmem_obj *obj)
1300 {
1301         return -1;
1302 }
1303
1304 static bool zcache_pampd_is_remote(void *pampd)
1305 {
1306         return 0;
1307 }
1308
1309 static struct tmem_pamops zcache_pamops = {
1310         .create = zcache_pampd_create,
1311         .get_data = zcache_pampd_get_data,
1312         .get_data_and_free = zcache_pampd_get_data_and_free,
1313         .free = zcache_pampd_free,
1314         .free_obj = zcache_pampd_free_obj,
1315         .new_obj = zcache_pampd_new_obj,
1316         .replace_in_obj = zcache_pampd_replace_in_obj,
1317         .is_remote = zcache_pampd_is_remote,
1318 };
1319
1320 /*
1321  * zcache compression/decompression and related per-cpu stuff
1322  */
1323
1324 static DEFINE_PER_CPU(unsigned char *, zcache_dstmem);
1325 #define ZCACHE_DSTMEM_ORDER 1
1326
1327 static int zcache_compress(struct page *from, void **out_va, unsigned *out_len)
1328 {
1329         int ret = 0;
1330         unsigned char *dmem = __get_cpu_var(zcache_dstmem);
1331         char *from_va;
1332
1333         BUG_ON(!irqs_disabled());
1334         if (unlikely(dmem == NULL))
1335                 goto out;  /* no buffer or no compressor so can't compress */
1336         *out_len = PAGE_SIZE << ZCACHE_DSTMEM_ORDER;
1337         from_va = kmap_atomic(from);
1338         mb();
1339         ret = zcache_comp_op(ZCACHE_COMPOP_COMPRESS, from_va, PAGE_SIZE, dmem,
1340                                 out_len);
1341         BUG_ON(ret);
1342         *out_va = dmem;
1343         kunmap_atomic(from_va);
1344         ret = 1;
1345 out:
1346         return ret;
1347 }
1348
1349 static int zcache_comp_cpu_up(int cpu)
1350 {
1351         struct crypto_comp *tfm;
1352
1353         tfm = crypto_alloc_comp(zcache_comp_name, 0, 0);
1354         if (IS_ERR(tfm))
1355                 return NOTIFY_BAD;
1356         *per_cpu_ptr(zcache_comp_pcpu_tfms, cpu) = tfm;
1357         return NOTIFY_OK;
1358 }
1359
1360 static void zcache_comp_cpu_down(int cpu)
1361 {
1362         struct crypto_comp *tfm;
1363
1364         tfm = *per_cpu_ptr(zcache_comp_pcpu_tfms, cpu);
1365         crypto_free_comp(tfm);
1366         *per_cpu_ptr(zcache_comp_pcpu_tfms, cpu) = NULL;
1367 }
1368
1369 static int zcache_cpu_notifier(struct notifier_block *nb,
1370                                 unsigned long action, void *pcpu)
1371 {
1372         int ret, cpu = (long)pcpu;
1373         struct zcache_preload *kp;
1374
1375         switch (action) {
1376         case CPU_UP_PREPARE:
1377                 ret = zcache_comp_cpu_up(cpu);
1378                 if (ret != NOTIFY_OK) {
1379                         pr_err("zcache: can't allocate compressor transform\n");
1380                         return ret;
1381                 }
1382                 per_cpu(zcache_dstmem, cpu) = (void *)__get_free_pages(
1383                         GFP_KERNEL | __GFP_REPEAT, ZCACHE_DSTMEM_ORDER);
1384                 break;
1385         case CPU_DEAD:
1386         case CPU_UP_CANCELED:
1387                 zcache_comp_cpu_down(cpu);
1388                 free_pages((unsigned long)per_cpu(zcache_dstmem, cpu),
1389                         ZCACHE_DSTMEM_ORDER);
1390                 per_cpu(zcache_dstmem, cpu) = NULL;
1391                 kp = &per_cpu(zcache_preloads, cpu);
1392                 while (kp->nr) {
1393                         kmem_cache_free(zcache_objnode_cache,
1394                                         kp->objnodes[kp->nr - 1]);
1395                         kp->objnodes[kp->nr - 1] = NULL;
1396                         kp->nr--;
1397                 }
1398                 if (kp->obj) {
1399                         kmem_cache_free(zcache_obj_cache, kp->obj);
1400                         kp->obj = NULL;
1401                 }
1402                 if (kp->page) {
1403                         free_page((unsigned long)kp->page);
1404                         kp->page = NULL;
1405                 }
1406                 break;
1407         default:
1408                 break;
1409         }
1410         return NOTIFY_OK;
1411 }
1412
1413 static struct notifier_block zcache_cpu_notifier_block = {
1414         .notifier_call = zcache_cpu_notifier
1415 };
1416
1417 #ifdef CONFIG_SYSFS
1418 #define ZCACHE_SYSFS_RO(_name) \
1419         static ssize_t zcache_##_name##_show(struct kobject *kobj, \
1420                                 struct kobj_attribute *attr, char *buf) \
1421         { \
1422                 return sprintf(buf, "%lu\n", zcache_##_name); \
1423         } \
1424         static struct kobj_attribute zcache_##_name##_attr = { \
1425                 .attr = { .name = __stringify(_name), .mode = 0444 }, \
1426                 .show = zcache_##_name##_show, \
1427         }
1428
1429 #define ZCACHE_SYSFS_RO_ATOMIC(_name) \
1430         static ssize_t zcache_##_name##_show(struct kobject *kobj, \
1431                                 struct kobj_attribute *attr, char *buf) \
1432         { \
1433             return sprintf(buf, "%d\n", atomic_read(&zcache_##_name)); \
1434         } \
1435         static struct kobj_attribute zcache_##_name##_attr = { \
1436                 .attr = { .name = __stringify(_name), .mode = 0444 }, \
1437                 .show = zcache_##_name##_show, \
1438         }
1439
1440 #define ZCACHE_SYSFS_RO_CUSTOM(_name, _func) \
1441         static ssize_t zcache_##_name##_show(struct kobject *kobj, \
1442                                 struct kobj_attribute *attr, char *buf) \
1443         { \
1444             return _func(buf); \
1445         } \
1446         static struct kobj_attribute zcache_##_name##_attr = { \
1447                 .attr = { .name = __stringify(_name), .mode = 0444 }, \
1448                 .show = zcache_##_name##_show, \
1449         }
1450
1451 ZCACHE_SYSFS_RO(curr_obj_count_max);
1452 ZCACHE_SYSFS_RO(curr_objnode_count_max);
1453 ZCACHE_SYSFS_RO(flush_total);
1454 ZCACHE_SYSFS_RO(flush_found);
1455 ZCACHE_SYSFS_RO(flobj_total);
1456 ZCACHE_SYSFS_RO(flobj_found);
1457 ZCACHE_SYSFS_RO(failed_eph_puts);
1458 ZCACHE_SYSFS_RO(failed_pers_puts);
1459 ZCACHE_SYSFS_RO(zbud_curr_zbytes);
1460 ZCACHE_SYSFS_RO(zbud_cumul_zpages);
1461 ZCACHE_SYSFS_RO(zbud_cumul_zbytes);
1462 ZCACHE_SYSFS_RO(zbud_buddied_count);
1463 ZCACHE_SYSFS_RO(zbpg_unused_list_count);
1464 ZCACHE_SYSFS_RO(evicted_raw_pages);
1465 ZCACHE_SYSFS_RO(evicted_unbuddied_pages);
1466 ZCACHE_SYSFS_RO(evicted_buddied_pages);
1467 ZCACHE_SYSFS_RO(failed_get_free_pages);
1468 ZCACHE_SYSFS_RO(failed_alloc);
1469 ZCACHE_SYSFS_RO(put_to_flush);
1470 ZCACHE_SYSFS_RO(compress_poor);
1471 ZCACHE_SYSFS_RO(mean_compress_poor);
1472 ZCACHE_SYSFS_RO_ATOMIC(zbud_curr_raw_pages);
1473 ZCACHE_SYSFS_RO_ATOMIC(zbud_curr_zpages);
1474 ZCACHE_SYSFS_RO_ATOMIC(curr_obj_count);
1475 ZCACHE_SYSFS_RO_ATOMIC(curr_objnode_count);
1476 ZCACHE_SYSFS_RO_CUSTOM(zbud_unbuddied_list_counts,
1477                         zbud_show_unbuddied_list_counts);
1478 ZCACHE_SYSFS_RO_CUSTOM(zbud_cumul_chunk_counts,
1479                         zbud_show_cumul_chunk_counts);
1480 ZCACHE_SYSFS_RO_CUSTOM(zv_curr_dist_counts,
1481                         zv_curr_dist_counts_show);
1482 ZCACHE_SYSFS_RO_CUSTOM(zv_cumul_dist_counts,
1483                         zv_cumul_dist_counts_show);
1484
1485 static struct attribute *zcache_attrs[] = {
1486         &zcache_curr_obj_count_attr.attr,
1487         &zcache_curr_obj_count_max_attr.attr,
1488         &zcache_curr_objnode_count_attr.attr,
1489         &zcache_curr_objnode_count_max_attr.attr,
1490         &zcache_flush_total_attr.attr,
1491         &zcache_flobj_total_attr.attr,
1492         &zcache_flush_found_attr.attr,
1493         &zcache_flobj_found_attr.attr,
1494         &zcache_failed_eph_puts_attr.attr,
1495         &zcache_failed_pers_puts_attr.attr,
1496         &zcache_compress_poor_attr.attr,
1497         &zcache_mean_compress_poor_attr.attr,
1498         &zcache_zbud_curr_raw_pages_attr.attr,
1499         &zcache_zbud_curr_zpages_attr.attr,
1500         &zcache_zbud_curr_zbytes_attr.attr,
1501         &zcache_zbud_cumul_zpages_attr.attr,
1502         &zcache_zbud_cumul_zbytes_attr.attr,
1503         &zcache_zbud_buddied_count_attr.attr,
1504         &zcache_zbpg_unused_list_count_attr.attr,
1505         &zcache_evicted_raw_pages_attr.attr,
1506         &zcache_evicted_unbuddied_pages_attr.attr,
1507         &zcache_evicted_buddied_pages_attr.attr,
1508         &zcache_failed_get_free_pages_attr.attr,
1509         &zcache_failed_alloc_attr.attr,
1510         &zcache_put_to_flush_attr.attr,
1511         &zcache_zbud_unbuddied_list_counts_attr.attr,
1512         &zcache_zbud_cumul_chunk_counts_attr.attr,
1513         &zcache_zv_curr_dist_counts_attr.attr,
1514         &zcache_zv_cumul_dist_counts_attr.attr,
1515         &zcache_zv_max_zsize_attr.attr,
1516         &zcache_zv_max_mean_zsize_attr.attr,
1517         &zcache_zv_page_count_policy_percent_attr.attr,
1518         NULL,
1519 };
1520
1521 static struct attribute_group zcache_attr_group = {
1522         .attrs = zcache_attrs,
1523         .name = "zcache",
1524 };
1525
1526 #endif /* CONFIG_SYSFS */
1527 /*
1528  * When zcache is disabled ("frozen"), pools can be created and destroyed,
1529  * but all puts (and thus all other operations that require memory allocation)
1530  * must fail.  If zcache is unfrozen, accepts puts, then frozen again,
1531  * data consistency requires all puts while frozen to be converted into
1532  * flushes.
1533  */
1534 static bool zcache_freeze;
1535
1536 /*
1537  * zcache shrinker interface (only useful for ephemeral pages, so zbud only)
1538  */
1539 static int shrink_zcache_memory(struct shrinker *shrink,
1540                                 struct shrink_control *sc)
1541 {
1542         int ret = -1;
1543         int nr = sc->nr_to_scan;
1544         gfp_t gfp_mask = sc->gfp_mask;
1545
1546         if (nr >= 0) {
1547                 if (!(gfp_mask & __GFP_FS))
1548                         /* does this case really need to be skipped? */
1549                         goto out;
1550                 zbud_evict_pages(nr);
1551         }
1552         ret = (int)atomic_read(&zcache_zbud_curr_raw_pages);
1553 out:
1554         return ret;
1555 }
1556
1557 static struct shrinker zcache_shrinker = {
1558         .shrink = shrink_zcache_memory,
1559         .seeks = DEFAULT_SEEKS,
1560 };
1561
1562 /*
1563  * zcache shims between cleancache/frontswap ops and tmem
1564  */
1565
1566 static int zcache_put_page(int cli_id, int pool_id, struct tmem_oid *oidp,
1567                                 uint32_t index, struct page *page)
1568 {
1569         struct tmem_pool *pool;
1570         int ret = -1;
1571
1572         BUG_ON(!irqs_disabled());
1573         pool = zcache_get_pool_by_id(cli_id, pool_id);
1574         if (unlikely(pool == NULL))
1575                 goto out;
1576         if (!zcache_freeze && zcache_do_preload(pool) == 0) {
1577                 /* preload does preempt_disable on success */
1578                 ret = tmem_put(pool, oidp, index, (char *)(page),
1579                                 PAGE_SIZE, 0, is_ephemeral(pool));
1580                 if (ret < 0) {
1581                         if (is_ephemeral(pool))
1582                                 zcache_failed_eph_puts++;
1583                         else
1584                                 zcache_failed_pers_puts++;
1585                 }
1586                 zcache_put_pool(pool);
1587                 preempt_enable_no_resched();
1588         } else {
1589                 zcache_put_to_flush++;
1590                 if (atomic_read(&pool->obj_count) > 0)
1591                         /* the put fails whether the flush succeeds or not */
1592                         (void)tmem_flush_page(pool, oidp, index);
1593                 zcache_put_pool(pool);
1594         }
1595 out:
1596         return ret;
1597 }
1598
1599 static int zcache_get_page(int cli_id, int pool_id, struct tmem_oid *oidp,
1600                                 uint32_t index, struct page *page)
1601 {
1602         struct tmem_pool *pool;
1603         int ret = -1;
1604         unsigned long flags;
1605         size_t size = PAGE_SIZE;
1606
1607         local_irq_save(flags);
1608         pool = zcache_get_pool_by_id(cli_id, pool_id);
1609         if (likely(pool != NULL)) {
1610                 if (atomic_read(&pool->obj_count) > 0)
1611                         ret = tmem_get(pool, oidp, index, (char *)(page),
1612                                         &size, 0, is_ephemeral(pool));
1613                 zcache_put_pool(pool);
1614         }
1615         local_irq_restore(flags);
1616         return ret;
1617 }
1618
1619 static int zcache_flush_page(int cli_id, int pool_id,
1620                                 struct tmem_oid *oidp, uint32_t index)
1621 {
1622         struct tmem_pool *pool;
1623         int ret = -1;
1624         unsigned long flags;
1625
1626         local_irq_save(flags);
1627         zcache_flush_total++;
1628         pool = zcache_get_pool_by_id(cli_id, pool_id);
1629         if (likely(pool != NULL)) {
1630                 if (atomic_read(&pool->obj_count) > 0)
1631                         ret = tmem_flush_page(pool, oidp, index);
1632                 zcache_put_pool(pool);
1633         }
1634         if (ret >= 0)
1635                 zcache_flush_found++;
1636         local_irq_restore(flags);
1637         return ret;
1638 }
1639
1640 static int zcache_flush_object(int cli_id, int pool_id,
1641                                 struct tmem_oid *oidp)
1642 {
1643         struct tmem_pool *pool;
1644         int ret = -1;
1645         unsigned long flags;
1646
1647         local_irq_save(flags);
1648         zcache_flobj_total++;
1649         pool = zcache_get_pool_by_id(cli_id, pool_id);
1650         if (likely(pool != NULL)) {
1651                 if (atomic_read(&pool->obj_count) > 0)
1652                         ret = tmem_flush_object(pool, oidp);
1653                 zcache_put_pool(pool);
1654         }
1655         if (ret >= 0)
1656                 zcache_flobj_found++;
1657         local_irq_restore(flags);
1658         return ret;
1659 }
1660
1661 static int zcache_destroy_pool(int cli_id, int pool_id)
1662 {
1663         struct tmem_pool *pool = NULL;
1664         struct zcache_client *cli = NULL;
1665         int ret = -1;
1666
1667         if (pool_id < 0)
1668                 goto out;
1669         if (cli_id == LOCAL_CLIENT)
1670                 cli = &zcache_host;
1671         else if ((unsigned int)cli_id < MAX_CLIENTS)
1672                 cli = &zcache_clients[cli_id];
1673         if (cli == NULL)
1674                 goto out;
1675         atomic_inc(&cli->refcount);
1676         pool = cli->tmem_pools[pool_id];
1677         if (pool == NULL)
1678                 goto out;
1679         cli->tmem_pools[pool_id] = NULL;
1680         /* wait for pool activity on other cpus to quiesce */
1681         while (atomic_read(&pool->refcount) != 0)
1682                 ;
1683         atomic_dec(&cli->refcount);
1684         local_bh_disable();
1685         ret = tmem_destroy_pool(pool);
1686         local_bh_enable();
1687         kfree(pool);
1688         pr_info("zcache: destroyed pool id=%d, cli_id=%d\n",
1689                         pool_id, cli_id);
1690 out:
1691         return ret;
1692 }
1693
1694 static int zcache_new_pool(uint16_t cli_id, uint32_t flags)
1695 {
1696         int poolid = -1;
1697         struct tmem_pool *pool;
1698         struct zcache_client *cli = NULL;
1699
1700         if (cli_id == LOCAL_CLIENT)
1701                 cli = &zcache_host;
1702         else if ((unsigned int)cli_id < MAX_CLIENTS)
1703                 cli = &zcache_clients[cli_id];
1704         if (cli == NULL)
1705                 goto out;
1706         atomic_inc(&cli->refcount);
1707         pool = kmalloc(sizeof(struct tmem_pool), GFP_ATOMIC);
1708         if (pool == NULL) {
1709                 pr_info("zcache: pool creation failed: out of memory\n");
1710                 goto out;
1711         }
1712
1713         for (poolid = 0; poolid < MAX_POOLS_PER_CLIENT; poolid++)
1714                 if (cli->tmem_pools[poolid] == NULL)
1715                         break;
1716         if (poolid >= MAX_POOLS_PER_CLIENT) {
1717                 pr_info("zcache: pool creation failed: max exceeded\n");
1718                 kfree(pool);
1719                 poolid = -1;
1720                 goto out;
1721         }
1722         atomic_set(&pool->refcount, 0);
1723         pool->client = cli;
1724         pool->pool_id = poolid;
1725         tmem_new_pool(pool, flags);
1726         cli->tmem_pools[poolid] = pool;
1727         pr_info("zcache: created %s tmem pool, id=%d, client=%d\n",
1728                 flags & TMEM_POOL_PERSIST ? "persistent" : "ephemeral",
1729                 poolid, cli_id);
1730 out:
1731         if (cli != NULL)
1732                 atomic_dec(&cli->refcount);
1733         return poolid;
1734 }
1735
1736 /**********
1737  * Two kernel functionalities currently can be layered on top of tmem.
1738  * These are "cleancache" which is used as a second-chance cache for clean
1739  * page cache pages; and "frontswap" which is used for swap pages
1740  * to avoid writes to disk.  A generic "shim" is provided here for each
1741  * to translate in-kernel semantics to zcache semantics.
1742  */
1743
1744 #ifdef CONFIG_CLEANCACHE
1745 static void zcache_cleancache_put_page(int pool_id,
1746                                         struct cleancache_filekey key,
1747                                         pgoff_t index, struct page *page)
1748 {
1749         u32 ind = (u32) index;
1750         struct tmem_oid oid = *(struct tmem_oid *)&key;
1751
1752         if (likely(ind == index))
1753                 (void)zcache_put_page(LOCAL_CLIENT, pool_id, &oid, index, page);
1754 }
1755
1756 static int zcache_cleancache_get_page(int pool_id,
1757                                         struct cleancache_filekey key,
1758                                         pgoff_t index, struct page *page)
1759 {
1760         u32 ind = (u32) index;
1761         struct tmem_oid oid = *(struct tmem_oid *)&key;
1762         int ret = -1;
1763
1764         if (likely(ind == index))
1765                 ret = zcache_get_page(LOCAL_CLIENT, pool_id, &oid, index, page);
1766         return ret;
1767 }
1768
1769 static void zcache_cleancache_flush_page(int pool_id,
1770                                         struct cleancache_filekey key,
1771                                         pgoff_t index)
1772 {
1773         u32 ind = (u32) index;
1774         struct tmem_oid oid = *(struct tmem_oid *)&key;
1775
1776         if (likely(ind == index))
1777                 (void)zcache_flush_page(LOCAL_CLIENT, pool_id, &oid, ind);
1778 }
1779
1780 static void zcache_cleancache_flush_inode(int pool_id,
1781                                         struct cleancache_filekey key)
1782 {
1783         struct tmem_oid oid = *(struct tmem_oid *)&key;
1784
1785         (void)zcache_flush_object(LOCAL_CLIENT, pool_id, &oid);
1786 }
1787
1788 static void zcache_cleancache_flush_fs(int pool_id)
1789 {
1790         if (pool_id >= 0)
1791                 (void)zcache_destroy_pool(LOCAL_CLIENT, pool_id);
1792 }
1793
1794 static int zcache_cleancache_init_fs(size_t pagesize)
1795 {
1796         BUG_ON(sizeof(struct cleancache_filekey) !=
1797                                 sizeof(struct tmem_oid));
1798         BUG_ON(pagesize != PAGE_SIZE);
1799         return zcache_new_pool(LOCAL_CLIENT, 0);
1800 }
1801
1802 static int zcache_cleancache_init_shared_fs(char *uuid, size_t pagesize)
1803 {
1804         /* shared pools are unsupported and map to private */
1805         BUG_ON(sizeof(struct cleancache_filekey) !=
1806                                 sizeof(struct tmem_oid));
1807         BUG_ON(pagesize != PAGE_SIZE);
1808         return zcache_new_pool(LOCAL_CLIENT, 0);
1809 }
1810
1811 static struct cleancache_ops zcache_cleancache_ops = {
1812         .put_page = zcache_cleancache_put_page,
1813         .get_page = zcache_cleancache_get_page,
1814         .invalidate_page = zcache_cleancache_flush_page,
1815         .invalidate_inode = zcache_cleancache_flush_inode,
1816         .invalidate_fs = zcache_cleancache_flush_fs,
1817         .init_shared_fs = zcache_cleancache_init_shared_fs,
1818         .init_fs = zcache_cleancache_init_fs
1819 };
1820
1821 struct cleancache_ops zcache_cleancache_register_ops(void)
1822 {
1823         struct cleancache_ops old_ops =
1824                 cleancache_register_ops(&zcache_cleancache_ops);
1825
1826         return old_ops;
1827 }
1828 #endif
1829
1830 #ifdef CONFIG_FRONTSWAP
1831 /* a single tmem poolid is used for all frontswap "types" (swapfiles) */
1832 static int zcache_frontswap_poolid = -1;
1833
1834 /*
1835  * Swizzling increases objects per swaptype, increasing tmem concurrency
1836  * for heavy swaploads.  Later, larger nr_cpus -> larger SWIZ_BITS
1837  * Setting SWIZ_BITS to 27 basically reconstructs the swap entry from
1838  * frontswap_load(), but has side-effects. Hence using 8.
1839  */
1840 #define SWIZ_BITS               8
1841 #define SWIZ_MASK               ((1 << SWIZ_BITS) - 1)
1842 #define _oswiz(_type, _ind)     ((_type << SWIZ_BITS) | (_ind & SWIZ_MASK))
1843 #define iswiz(_ind)             (_ind >> SWIZ_BITS)
1844
1845 static inline struct tmem_oid oswiz(unsigned type, u32 ind)
1846 {
1847         struct tmem_oid oid = { .oid = { 0 } };
1848         oid.oid[0] = _oswiz(type, ind);
1849         return oid;
1850 }
1851
1852 static int zcache_frontswap_store(unsigned type, pgoff_t offset,
1853                                    struct page *page)
1854 {
1855         u64 ind64 = (u64)offset;
1856         u32 ind = (u32)offset;
1857         struct tmem_oid oid = oswiz(type, ind);
1858         int ret = -1;
1859         unsigned long flags;
1860
1861         BUG_ON(!PageLocked(page));
1862         if (likely(ind64 == ind)) {
1863                 local_irq_save(flags);
1864                 ret = zcache_put_page(LOCAL_CLIENT, zcache_frontswap_poolid,
1865                                         &oid, iswiz(ind), page);
1866                 local_irq_restore(flags);
1867         }
1868         return ret;
1869 }
1870
1871 /* returns 0 if the page was successfully gotten from frontswap, -1 if
1872  * was not present (should never happen!) */
1873 static int zcache_frontswap_load(unsigned type, pgoff_t offset,
1874                                    struct page *page)
1875 {
1876         u64 ind64 = (u64)offset;
1877         u32 ind = (u32)offset;
1878         struct tmem_oid oid = oswiz(type, ind);
1879         int ret = -1;
1880
1881         BUG_ON(!PageLocked(page));
1882         if (likely(ind64 == ind))
1883                 ret = zcache_get_page(LOCAL_CLIENT, zcache_frontswap_poolid,
1884                                         &oid, iswiz(ind), page);
1885         return ret;
1886 }
1887
1888 /* flush a single page from frontswap */
1889 static void zcache_frontswap_flush_page(unsigned type, pgoff_t offset)
1890 {
1891         u64 ind64 = (u64)offset;
1892         u32 ind = (u32)offset;
1893         struct tmem_oid oid = oswiz(type, ind);
1894
1895         if (likely(ind64 == ind))
1896                 (void)zcache_flush_page(LOCAL_CLIENT, zcache_frontswap_poolid,
1897                                         &oid, iswiz(ind));
1898 }
1899
1900 /* flush all pages from the passed swaptype */
1901 static void zcache_frontswap_flush_area(unsigned type)
1902 {
1903         struct tmem_oid oid;
1904         int ind;
1905
1906         for (ind = SWIZ_MASK; ind >= 0; ind--) {
1907                 oid = oswiz(type, ind);
1908                 (void)zcache_flush_object(LOCAL_CLIENT,
1909                                                 zcache_frontswap_poolid, &oid);
1910         }
1911 }
1912
1913 static void zcache_frontswap_init(unsigned ignored)
1914 {
1915         /* a single tmem poolid is used for all frontswap "types" (swapfiles) */
1916         if (zcache_frontswap_poolid < 0)
1917                 zcache_frontswap_poolid =
1918                         zcache_new_pool(LOCAL_CLIENT, TMEM_POOL_PERSIST);
1919 }
1920
1921 static struct frontswap_ops zcache_frontswap_ops = {
1922         .store = zcache_frontswap_store,
1923         .load = zcache_frontswap_load,
1924         .invalidate_page = zcache_frontswap_flush_page,
1925         .invalidate_area = zcache_frontswap_flush_area,
1926         .init = zcache_frontswap_init
1927 };
1928
1929 struct frontswap_ops zcache_frontswap_register_ops(void)
1930 {
1931         struct frontswap_ops old_ops =
1932                 frontswap_register_ops(&zcache_frontswap_ops);
1933
1934         return old_ops;
1935 }
1936 #endif
1937
1938 /*
1939  * zcache initialization
1940  * NOTE FOR NOW zcache MUST BE PROVIDED AS A KERNEL BOOT PARAMETER OR
1941  * NOTHING HAPPENS!
1942  */
1943
1944 static int zcache_enabled;
1945
1946 static int __init enable_zcache(char *s)
1947 {
1948         zcache_enabled = 1;
1949         return 1;
1950 }
1951 __setup("zcache", enable_zcache);
1952
1953 /* allow independent dynamic disabling of cleancache and frontswap */
1954
1955 static int use_cleancache = 1;
1956
1957 static int __init no_cleancache(char *s)
1958 {
1959         use_cleancache = 0;
1960         return 1;
1961 }
1962
1963 __setup("nocleancache", no_cleancache);
1964
1965 static int use_frontswap = 1;
1966
1967 static int __init no_frontswap(char *s)
1968 {
1969         use_frontswap = 0;
1970         return 1;
1971 }
1972
1973 __setup("nofrontswap", no_frontswap);
1974
1975 static int __init enable_zcache_compressor(char *s)
1976 {
1977         strncpy(zcache_comp_name, s, ZCACHE_COMP_NAME_SZ);
1978         zcache_enabled = 1;
1979         return 1;
1980 }
1981 __setup("zcache=", enable_zcache_compressor);
1982
1983
1984 static int zcache_comp_init(void)
1985 {
1986         int ret = 0;
1987
1988         /* check crypto algorithm */
1989         if (*zcache_comp_name != '\0') {
1990                 ret = crypto_has_comp(zcache_comp_name, 0, 0);
1991                 if (!ret)
1992                         pr_info("zcache: %s not supported\n",
1993                                         zcache_comp_name);
1994         }
1995         if (!ret)
1996                 strcpy(zcache_comp_name, "lzo");
1997         ret = crypto_has_comp(zcache_comp_name, 0, 0);
1998         if (!ret) {
1999                 ret = 1;
2000                 goto out;
2001         }
2002         pr_info("zcache: using %s compressor\n", zcache_comp_name);
2003
2004         /* alloc percpu transforms */
2005         ret = 0;
2006         zcache_comp_pcpu_tfms = alloc_percpu(struct crypto_comp *);
2007         if (!zcache_comp_pcpu_tfms)
2008                 ret = 1;
2009 out:
2010         return ret;
2011 }
2012
2013 static int __init zcache_init(void)
2014 {
2015         int ret = 0;
2016
2017 #ifdef CONFIG_SYSFS
2018         ret = sysfs_create_group(mm_kobj, &zcache_attr_group);
2019         if (ret) {
2020                 pr_err("zcache: can't create sysfs\n");
2021                 goto out;
2022         }
2023 #endif /* CONFIG_SYSFS */
2024 #if defined(CONFIG_CLEANCACHE) || defined(CONFIG_FRONTSWAP)
2025         if (zcache_enabled) {
2026                 unsigned int cpu;
2027
2028                 tmem_register_hostops(&zcache_hostops);
2029                 tmem_register_pamops(&zcache_pamops);
2030                 ret = register_cpu_notifier(&zcache_cpu_notifier_block);
2031                 if (ret) {
2032                         pr_err("zcache: can't register cpu notifier\n");
2033                         goto out;
2034                 }
2035                 ret = zcache_comp_init();
2036                 if (ret) {
2037                         pr_err("zcache: compressor initialization failed\n");
2038                         goto out;
2039                 }
2040                 for_each_online_cpu(cpu) {
2041                         void *pcpu = (void *)(long)cpu;
2042                         zcache_cpu_notifier(&zcache_cpu_notifier_block,
2043                                 CPU_UP_PREPARE, pcpu);
2044                 }
2045         }
2046         zcache_objnode_cache = kmem_cache_create("zcache_objnode",
2047                                 sizeof(struct tmem_objnode), 0, 0, NULL);
2048         zcache_obj_cache = kmem_cache_create("zcache_obj",
2049                                 sizeof(struct tmem_obj), 0, 0, NULL);
2050         ret = zcache_new_client(LOCAL_CLIENT);
2051         if (ret) {
2052                 pr_err("zcache: can't create client\n");
2053                 goto out;
2054         }
2055 #endif
2056 #ifdef CONFIG_CLEANCACHE
2057         if (zcache_enabled && use_cleancache) {
2058                 struct cleancache_ops old_ops;
2059
2060                 zbud_init();
2061                 register_shrinker(&zcache_shrinker);
2062                 old_ops = zcache_cleancache_register_ops();
2063                 pr_info("zcache: cleancache enabled using kernel "
2064                         "transcendent memory and compression buddies\n");
2065                 if (old_ops.init_fs != NULL)
2066                         pr_warning("zcache: cleancache_ops overridden");
2067         }
2068 #endif
2069 #ifdef CONFIG_FRONTSWAP
2070         if (zcache_enabled && use_frontswap) {
2071                 struct frontswap_ops old_ops;
2072
2073                 old_ops = zcache_frontswap_register_ops();
2074                 pr_info("zcache: frontswap enabled using kernel "
2075                         "transcendent memory and zsmalloc\n");
2076                 if (old_ops.init != NULL)
2077                         pr_warning("zcache: frontswap_ops overridden");
2078         }
2079 #endif
2080 out:
2081         return ret;
2082 }
2083
2084 module_init(zcache_init)