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