tags/3.0-30/1800_fix-zcache-build.patch

diff --git a/drivers/staging/zcache/Makefile b/drivers/staging/zcache/Makefile
index f5ec64f..e3c945f 100644
--- a/drivers/staging/zcache/Makefile
+++ b/drivers/staging/zcache/Makefile
@@ -1,3 +1,3 @@
-zcache-y       :=      tmem.o
+zcache-y       :=      zcache_drv.o tmem.o
 
 obj-$(CONFIG_ZCACHE)   +=      zcache.o
diff --git a/drivers/staging/zcache/zcache.c b/drivers/staging/zcache/zcache.c
deleted file mode 100644
index 77ac2d4..0000000
--- a/drivers/staging/zcache/zcache.c
+++ /dev/null
@@ -1,1661 +0,0 @@
-/*
- * zcache.c
- *
- * Copyright (c) 2010,2011, Dan Magenheimer, Oracle Corp.
- * Copyright (c) 2010,2011, Nitin Gupta
- *
- * Zcache provides an in-kernel "host implementation" for transcendent memory
- * and, thus indirectly, for cleancache and frontswap.  Zcache includes two
- * page-accessible memory [1] interfaces, both utilizing lzo1x compression:
- * 1) "compression buddies" ("zbud") is used for ephemeral pages
- * 2) xvmalloc is used for persistent pages.
- * Xvmalloc (based on the TLSF allocator) has very low fragmentation
- * so maximizes space efficiency, while zbud allows pairs (and potentially,
- * in the future, more than a pair of) compressed pages to be closely linked
- * so that reclaiming can be done via the kernel's physical-page-oriented
- * "shrinker" interface.
- *
- * [1] For a definition of page-accessible memory (aka PAM), see:
- *   http://marc.info/?l=linux-mm&m=127811271605009
- */
-
-#include <linux/cpu.h>
-#include <linux/highmem.h>
-#include <linux/list.h>
-#include <linux/lzo.h>
-#include <linux/slab.h>
-#include <linux/spinlock.h>
-#include <linux/types.h>
-#include <linux/atomic.h>
-#include "tmem.h"
-
-#include "../zram/xvmalloc.h" /* if built in drivers/staging */
-
-#if (!defined(CONFIG_CLEANCACHE) && !defined(CONFIG_FRONTSWAP))
-#error "zcache is useless without CONFIG_CLEANCACHE or CONFIG_FRONTSWAP"
-#endif
-#ifdef CONFIG_CLEANCACHE
-#include <linux/cleancache.h>
-#endif
-#ifdef CONFIG_FRONTSWAP
-#include <linux/frontswap.h>
-#endif
-
-#if 0
-/* this is more aggressive but may cause other problems? */
-#define ZCACHE_GFP_MASK        (GFP_ATOMIC | __GFP_NORETRY | __GFP_NOWARN)
-#else
-#define ZCACHE_GFP_MASK \
-       (__GFP_FS | __GFP_NORETRY | __GFP_NOWARN | __GFP_NOMEMALLOC)
-#endif
-
-/**********
- * Compression buddies ("zbud") provides for packing two (or, possibly
- * in the future, more) compressed ephemeral pages into a single "raw"
- * (physical) page and tracking them with data structures so that
- * the raw pages can be easily reclaimed.
- *
- * A zbud page ("zbpg") is an aligned page containing a list_head,
- * a lock, and two "zbud headers".  The remainder of the physical
- * page is divided up into aligned 64-byte "chunks" which contain
- * the compressed data for zero, one, or two zbuds.  Each zbpg
- * resides on: (1) an "unused list" if it has no zbuds; (2) a
- * "buddied" list if it is fully populated  with two zbuds; or
- * (3) one of PAGE_SIZE/64 "unbuddied" lists indexed by how many chunks
- * the one unbuddied zbud uses.  The data inside a zbpg cannot be
- * read or written unless the zbpg's lock is held.
- */
-
-#define ZBH_SENTINEL  0x43214321
-#define ZBPG_SENTINEL  0xdeadbeef
-
-#define ZBUD_MAX_BUDS 2
-
-struct zbud_hdr {
-       uint32_t pool_id;
-       struct tmem_oid oid;
-       uint32_t index;
-       uint16_t size; /* compressed size in bytes, zero means unused */
-       DECL_SENTINEL
-};
-
-struct zbud_page {
-       struct list_head bud_list;
-       spinlock_t lock;
-       struct zbud_hdr buddy[ZBUD_MAX_BUDS];
-       DECL_SENTINEL
-       /* followed by NUM_CHUNK aligned CHUNK_SIZE-byte chunks */
-};
-
-#define CHUNK_SHIFT    6
-#define CHUNK_SIZE     (1 << CHUNK_SHIFT)
-#define CHUNK_MASK     (~(CHUNK_SIZE-1))
-#define NCHUNKS                (((PAGE_SIZE - sizeof(struct zbud_page)) & \
-                               CHUNK_MASK) >> CHUNK_SHIFT)
-#define MAX_CHUNK      (NCHUNKS-1)
-
-static struct {
-       struct list_head list;
-       unsigned count;
-} zbud_unbuddied[NCHUNKS];
-/* list N contains pages with N chunks USED and NCHUNKS-N unused */
-/* element 0 is never used but optimizing that isn't worth it */
-static unsigned long zbud_cumul_chunk_counts[NCHUNKS];
-
-struct list_head zbud_buddied_list;
-static unsigned long zcache_zbud_buddied_count;
-
-/* protects the buddied list and all unbuddied lists */
-static DEFINE_SPINLOCK(zbud_budlists_spinlock);
-
-static LIST_HEAD(zbpg_unused_list);
-static unsigned long zcache_zbpg_unused_list_count;
-
-/* protects the unused page list */
-static DEFINE_SPINLOCK(zbpg_unused_list_spinlock);
-
-static atomic_t zcache_zbud_curr_raw_pages;
-static atomic_t zcache_zbud_curr_zpages;
-static unsigned long zcache_zbud_curr_zbytes;
-static unsigned long zcache_zbud_cumul_zpages;
-static unsigned long zcache_zbud_cumul_zbytes;
-static unsigned long zcache_compress_poor;
-
-/* forward references */
-static void *zcache_get_free_page(void);
-static void zcache_free_page(void *p);
-
-/*
- * zbud helper functions
- */
-
-static inline unsigned zbud_max_buddy_size(void)
-{
-       return MAX_CHUNK << CHUNK_SHIFT;
-}
-
-static inline unsigned zbud_size_to_chunks(unsigned size)
-{
-       BUG_ON(size == 0 || size > zbud_max_buddy_size());
-       return (size + CHUNK_SIZE - 1) >> CHUNK_SHIFT;
-}
-
-static inline int zbud_budnum(struct zbud_hdr *zh)
-{
-       unsigned offset = (unsigned long)zh & (PAGE_SIZE - 1);
-       struct zbud_page *zbpg = NULL;
-       unsigned budnum = -1U;
-       int i;
-
-       for (i = 0; i < ZBUD_MAX_BUDS; i++)
-               if (offset == offsetof(typeof(*zbpg), buddy[i])) {
-                       budnum = i;
-                       break;
-               }
-       BUG_ON(budnum == -1U);
-       return budnum;
-}
-
-static char *zbud_data(struct zbud_hdr *zh, unsigned size)
-{
-       struct zbud_page *zbpg;
-       char *p;
-       unsigned budnum;
-
-       ASSERT_SENTINEL(zh, ZBH);
-       budnum = zbud_budnum(zh);
-       BUG_ON(size == 0 || size > zbud_max_buddy_size());
-       zbpg = container_of(zh, struct zbud_page, buddy[budnum]);
-       ASSERT_SPINLOCK(&zbpg->lock);
-       p = (char *)zbpg;
-       if (budnum == 0)
-               p += ((sizeof(struct zbud_page) + CHUNK_SIZE - 1) &
-                                                       CHUNK_MASK);
-       else if (budnum == 1)
-               p += PAGE_SIZE - ((size + CHUNK_SIZE - 1) & CHUNK_MASK);
-       return p;
-}
-
-/*
- * zbud raw page management
- */
-
-static struct zbud_page *zbud_alloc_raw_page(void)
-{
-       struct zbud_page *zbpg = NULL;
-       struct zbud_hdr *zh0, *zh1;
-       bool recycled = 0;
-
-       /* if any pages on the zbpg list, use one */
-       spin_lock(&zbpg_unused_list_spinlock);
-       if (!list_empty(&zbpg_unused_list)) {
-               zbpg = list_first_entry(&zbpg_unused_list,
-                               struct zbud_page, bud_list);
-               list_del_init(&zbpg->bud_list);
-               zcache_zbpg_unused_list_count--;
-               recycled = 1;
-       }
-       spin_unlock(&zbpg_unused_list_spinlock);
-       if (zbpg == NULL)
-               /* none on zbpg list, try to get a kernel page */
-               zbpg = zcache_get_free_page();
-       if (likely(zbpg != NULL)) {
-               INIT_LIST_HEAD(&zbpg->bud_list);
-               zh0 = &zbpg->buddy[0]; zh1 = &zbpg->buddy[1];
-               spin_lock_init(&zbpg->lock);
-               if (recycled) {
-                       ASSERT_INVERTED_SENTINEL(zbpg, ZBPG);
-                       SET_SENTINEL(zbpg, ZBPG);
-                       BUG_ON(zh0->size != 0 || tmem_oid_valid(&zh0->oid));
-                       BUG_ON(zh1->size != 0 || tmem_oid_valid(&zh1->oid));
-               } else {
-                       atomic_inc(&zcache_zbud_curr_raw_pages);
-                       INIT_LIST_HEAD(&zbpg->bud_list);
-                       SET_SENTINEL(zbpg, ZBPG);
-                       zh0->size = 0; zh1->size = 0;
-                       tmem_oid_set_invalid(&zh0->oid);
-                       tmem_oid_set_invalid(&zh1->oid);
-               }
-       }
-       return zbpg;
-}
-
-static void zbud_free_raw_page(struct zbud_page *zbpg)
-{
-       struct zbud_hdr *zh0 = &zbpg->buddy[0], *zh1 = &zbpg->buddy[1];
-
-       ASSERT_SENTINEL(zbpg, ZBPG);
-       BUG_ON(!list_empty(&zbpg->bud_list));
-       ASSERT_SPINLOCK(&zbpg->lock);
-       BUG_ON(zh0->size != 0 || tmem_oid_valid(&zh0->oid));
-       BUG_ON(zh1->size != 0 || tmem_oid_valid(&zh1->oid));
-       INVERT_SENTINEL(zbpg, ZBPG);
-       spin_unlock(&zbpg->lock);
-       spin_lock(&zbpg_unused_list_spinlock);
-       list_add(&zbpg->bud_list, &zbpg_unused_list);
-       zcache_zbpg_unused_list_count++;
-       spin_unlock(&zbpg_unused_list_spinlock);
-}
-
-/*
- * core zbud handling routines
- */
-
-static unsigned zbud_free(struct zbud_hdr *zh)
-{
-       unsigned size;
-
-       ASSERT_SENTINEL(zh, ZBH);
-       BUG_ON(!tmem_oid_valid(&zh->oid));
-       size = zh->size;
-       BUG_ON(zh->size == 0 || zh->size > zbud_max_buddy_size());
-       zh->size = 0;
-       tmem_oid_set_invalid(&zh->oid);
-       INVERT_SENTINEL(zh, ZBH);
-       zcache_zbud_curr_zbytes -= size;
-       atomic_dec(&zcache_zbud_curr_zpages);
-       return size;
-}
-
-static void zbud_free_and_delist(struct zbud_hdr *zh)
-{
-       unsigned chunks;
-       struct zbud_hdr *zh_other;
-       unsigned budnum = zbud_budnum(zh), size;
-       struct zbud_page *zbpg =
-               container_of(zh, struct zbud_page, buddy[budnum]);
-
-       spin_lock(&zbpg->lock);
-       if (list_empty(&zbpg->bud_list)) {
-               /* ignore zombie page... see zbud_evict_pages() */
-               spin_unlock(&zbpg->lock);
-               return;
-       }
-       size = zbud_free(zh);
-       ASSERT_SPINLOCK(&zbpg->lock);
-       zh_other = &zbpg->buddy[(budnum == 0) ? 1 : 0];
-       if (zh_other->size == 0) { /* was unbuddied: unlist and free */
-               chunks = zbud_size_to_chunks(size) ;
-               spin_lock(&zbud_budlists_spinlock);
-               BUG_ON(list_empty(&zbud_unbuddied[chunks].list));
-               list_del_init(&zbpg->bud_list);
-               zbud_unbuddied[chunks].count--;
-               spin_unlock(&zbud_budlists_spinlock);
-               zbud_free_raw_page(zbpg);
-       } else { /* was buddied: move remaining buddy to unbuddied list */
-               chunks = zbud_size_to_chunks(zh_other->size) ;
-               spin_lock(&zbud_budlists_spinlock);
-               list_del_init(&zbpg->bud_list);
-               zcache_zbud_buddied_count--;
-               list_add_tail(&zbpg->bud_list, &zbud_unbuddied[chunks].list);
-               zbud_unbuddied[chunks].count++;
-               spin_unlock(&zbud_budlists_spinlock);
-               spin_unlock(&zbpg->lock);
-       }
-}
-
-static struct zbud_hdr *zbud_create(uint32_t pool_id, struct tmem_oid *oid,
-                                       uint32_t index, struct page *page,
-                                       void *cdata, unsigned size)
-{
-       struct zbud_hdr *zh0, *zh1, *zh = NULL;
-       struct zbud_page *zbpg = NULL, *ztmp;
-       unsigned nchunks;
-       char *to;
-       int i, found_good_buddy = 0;
-
-       nchunks = zbud_size_to_chunks(size) ;
-       for (i = MAX_CHUNK - nchunks + 1; i > 0; i--) {
-               spin_lock(&zbud_budlists_spinlock);
-               if (!list_empty(&zbud_unbuddied[i].list)) {
-                       list_for_each_entry_safe(zbpg, ztmp,
-                                   &zbud_unbuddied[i].list, bud_list) {
-                               if (spin_trylock(&zbpg->lock)) {
-                                       found_good_buddy = i;
-                                       goto found_unbuddied;
-                               }
-                       }
-               }
-               spin_unlock(&zbud_budlists_spinlock);
-       }
-       /* didn't find a good buddy, try allocating a new page */
-       zbpg = zbud_alloc_raw_page();
-       if (unlikely(zbpg == NULL))
-               goto out;
-       /* ok, have a page, now compress the data before taking locks */
-       spin_lock(&zbpg->lock);
-       spin_lock(&zbud_budlists_spinlock);
-       list_add_tail(&zbpg->bud_list, &zbud_unbuddied[nchunks].list);
-       zbud_unbuddied[nchunks].count++;
-       zh = &zbpg->buddy[0];
-       goto init_zh;
-
-found_unbuddied:
-       ASSERT_SPINLOCK(&zbpg->lock);
-       zh0 = &zbpg->buddy[0]; zh1 = &zbpg->buddy[1];
-       BUG_ON(!((zh0->size == 0) ^ (zh1->size == 0)));
-       if (zh0->size != 0) { /* buddy0 in use, buddy1 is vacant */
-               ASSERT_SENTINEL(zh0, ZBH);
-               zh = zh1;
-       } else if (zh1->size != 0) { /* buddy1 in use, buddy0 is vacant */
-               ASSERT_SENTINEL(zh1, ZBH);
-               zh = zh0;
-       } else
-               BUG();
-       list_del_init(&zbpg->bud_list);
-       zbud_unbuddied[found_good_buddy].count--;
-       list_add_tail(&zbpg->bud_list, &zbud_buddied_list);
-       zcache_zbud_buddied_count++;
-
-init_zh:
-       SET_SENTINEL(zh, ZBH);
-       zh->size = size;
-       zh->index = index;
-       zh->oid = *oid;
-       zh->pool_id = pool_id;
-       /* can wait to copy the data until the list locks are dropped */
-       spin_unlock(&zbud_budlists_spinlock);
-
-       to = zbud_data(zh, size);
-       memcpy(to, cdata, size);
-       spin_unlock(&zbpg->lock);
-       zbud_cumul_chunk_counts[nchunks]++;
-       atomic_inc(&zcache_zbud_curr_zpages);
-       zcache_zbud_cumul_zpages++;
-       zcache_zbud_curr_zbytes += size;
-       zcache_zbud_cumul_zbytes += size;
-out:
-       return zh;
-}
-
-static int zbud_decompress(struct page *page, struct zbud_hdr *zh)
-{
-       struct zbud_page *zbpg;
-       unsigned budnum = zbud_budnum(zh);
-       size_t out_len = PAGE_SIZE;
-       char *to_va, *from_va;
-       unsigned size;
-       int ret = 0;
-
-       zbpg = container_of(zh, struct zbud_page, buddy[budnum]);
-       spin_lock(&zbpg->lock);
-       if (list_empty(&zbpg->bud_list)) {
-               /* ignore zombie page... see zbud_evict_pages() */
-               ret = -EINVAL;
-               goto out;
-       }
-       ASSERT_SENTINEL(zh, ZBH);
-       BUG_ON(zh->size == 0 || zh->size > zbud_max_buddy_size());
-       to_va = kmap_atomic(page, KM_USER0);
-       size = zh->size;
-       from_va = zbud_data(zh, size);
-       ret = lzo1x_decompress_safe(from_va, size, to_va, &out_len);
-       BUG_ON(ret != LZO_E_OK);
-       BUG_ON(out_len != PAGE_SIZE);
-       kunmap_atomic(to_va, KM_USER0);
-out:
-       spin_unlock(&zbpg->lock);
-       return ret;
-}
-
-/*
- * The following routines handle shrinking of ephemeral pages by evicting
- * pages "least valuable" first.
- */
-
-static unsigned long zcache_evicted_raw_pages;
-static unsigned long zcache_evicted_buddied_pages;
-static unsigned long zcache_evicted_unbuddied_pages;
-
-static struct tmem_pool *zcache_get_pool_by_id(uint32_t poolid);
-static void zcache_put_pool(struct tmem_pool *pool);
-
-/*
- * Flush and free all zbuds in a zbpg, then free the pageframe
- */
-static void zbud_evict_zbpg(struct zbud_page *zbpg)
-{
-       struct zbud_hdr *zh;
-       int i, j;
-       uint32_t pool_id[ZBUD_MAX_BUDS], index[ZBUD_MAX_BUDS];
-       struct tmem_oid oid[ZBUD_MAX_BUDS];
-       struct tmem_pool *pool;
-
-       ASSERT_SPINLOCK(&zbpg->lock);
-       BUG_ON(!list_empty(&zbpg->bud_list));
-       for (i = 0, j = 0; i < ZBUD_MAX_BUDS; i++) {
-               zh = &zbpg->buddy[i];
-               if (zh->size) {
-                       pool_id[j] = zh->pool_id;
-                       oid[j] = zh->oid;
-                       index[j] = zh->index;
-                       j++;
-                       zbud_free(zh);
-               }
-       }
-       spin_unlock(&zbpg->lock);
-       for (i = 0; i < j; i++) {
-               pool = zcache_get_pool_by_id(pool_id[i]);
-               if (pool != NULL) {
-                       tmem_flush_page(pool, &oid[i], index[i]);
-                       zcache_put_pool(pool);
-               }
-       }
-       ASSERT_SENTINEL(zbpg, ZBPG);
-       spin_lock(&zbpg->lock);
-       zbud_free_raw_page(zbpg);
-}
-
-/*
- * Free nr pages.  This code is funky because we want to hold the locks
- * protecting various lists for as short a time as possible, and in some
- * circumstances the list may change asynchronously when the list lock is
- * not held.  In some cases we also trylock not only to avoid waiting on a
- * page in use by another cpu, but also to avoid potential deadlock due to
- * lock inversion.
- */
-static void zbud_evict_pages(int nr)
-{
-       struct zbud_page *zbpg;
-       int i;
-
-       /* first try freeing any pages on unused list */
-retry_unused_list:
-       spin_lock_bh(&zbpg_unused_list_spinlock);
-       if (!list_empty(&zbpg_unused_list)) {
-               /* can't walk list here, since it may change when unlocked */
-               zbpg = list_first_entry(&zbpg_unused_list,
-                               struct zbud_page, bud_list);
-               list_del_init(&zbpg->bud_list);
-               zcache_zbpg_unused_list_count--;
-               atomic_dec(&zcache_zbud_curr_raw_pages);
-               spin_unlock_bh(&zbpg_unused_list_spinlock);
-               zcache_free_page(zbpg);
-               zcache_evicted_raw_pages++;
-               if (--nr <= 0)
-                       goto out;
-               goto retry_unused_list;
-       }
-       spin_unlock_bh(&zbpg_unused_list_spinlock);
-
-       /* now try freeing unbuddied pages, starting with least space avail */
-       for (i = 0; i < MAX_CHUNK; i++) {
-retry_unbud_list_i:
-               spin_lock_bh(&zbud_budlists_spinlock);
-               if (list_empty(&zbud_unbuddied[i].list)) {
-                       spin_unlock_bh(&zbud_budlists_spinlock);
-                       continue;
-               }
-               list_for_each_entry(zbpg, &zbud_unbuddied[i].list, bud_list) {
-                       if (unlikely(!spin_trylock(&zbpg->lock)))
-                               continue;
-                       list_del_init(&zbpg->bud_list);
-                       zbud_unbuddied[i].count--;
-                       spin_unlock(&zbud_budlists_spinlock);
-                       zcache_evicted_unbuddied_pages++;
-                       /* want budlists unlocked when doing zbpg eviction */
-                       zbud_evict_zbpg(zbpg);
-                       local_bh_enable();
-                       if (--nr <= 0)
-                               goto out;
-                       goto retry_unbud_list_i;
-               }
-               spin_unlock_bh(&zbud_budlists_spinlock);
-       }
-
-       /* as a last resort, free buddied pages */
-retry_bud_list:
-       spin_lock_bh(&zbud_budlists_spinlock);
-       if (list_empty(&zbud_buddied_list)) {
-               spin_unlock_bh(&zbud_budlists_spinlock);
-               goto out;
-       }
-       list_for_each_entry(zbpg, &zbud_buddied_list, bud_list) {
-               if (unlikely(!spin_trylock(&zbpg->lock)))
-                       continue;
-               list_del_init(&zbpg->bud_list);
-               zcache_zbud_buddied_count--;
-               spin_unlock(&zbud_budlists_spinlock);
-               zcache_evicted_buddied_pages++;
-               /* want budlists unlocked when doing zbpg eviction */
-               zbud_evict_zbpg(zbpg);
-               local_bh_enable();
-               if (--nr <= 0)
-                       goto out;
-               goto retry_bud_list;
-       }
-       spin_unlock_bh(&zbud_budlists_spinlock);
-out:
-       return;
-}
-
-static void zbud_init(void)
-{
-       int i;
-
-       INIT_LIST_HEAD(&zbud_buddied_list);
-       zcache_zbud_buddied_count = 0;
-       for (i = 0; i < NCHUNKS; i++) {
-               INIT_LIST_HEAD(&zbud_unbuddied[i].list);
-               zbud_unbuddied[i].count = 0;
-       }
-}
-
-#ifdef CONFIG_SYSFS
-/*
- * These sysfs routines show a nice distribution of how many zbpg's are
- * currently (and have ever been placed) in each unbuddied list.  It's fun
- * to watch but can probably go away before final merge.
- */
-static int zbud_show_unbuddied_list_counts(char *buf)
-{
-       int i;
-       char *p = buf;
-
-       for (i = 0; i < NCHUNKS - 1; i++)
-               p += sprintf(p, "%u ", zbud_unbuddied[i].count);
-       p += sprintf(p, "%d\n", zbud_unbuddied[i].count);
-       return p - buf;
-}
-
-static int zbud_show_cumul_chunk_counts(char *buf)
-{
-       unsigned long i, chunks = 0, total_chunks = 0, sum_total_chunks = 0;
-       unsigned long total_chunks_lte_21 = 0, total_chunks_lte_32 = 0;
-       unsigned long total_chunks_lte_42 = 0;
-       char *p = buf;
-
-       for (i = 0; i < NCHUNKS; i++) {
-               p += sprintf(p, "%lu ", zbud_cumul_chunk_counts[i]);
-               chunks += zbud_cumul_chunk_counts[i];
-               total_chunks += zbud_cumul_chunk_counts[i];
-               sum_total_chunks += i * zbud_cumul_chunk_counts[i];
-               if (i == 21)
-                       total_chunks_lte_21 = total_chunks;
-               if (i == 32)
-                       total_chunks_lte_32 = total_chunks;
-               if (i == 42)
-                       total_chunks_lte_42 = total_chunks;
-       }
-       p += sprintf(p, "<=21:%lu <=32:%lu <=42:%lu, mean:%lu\n",
-               total_chunks_lte_21, total_chunks_lte_32, total_chunks_lte_42,
-               chunks == 0 ? 0 : sum_total_chunks / chunks);
-       return p - buf;
-}
-#endif
-
-/**********
- * This "zv" PAM implementation combines the TLSF-based xvMalloc
- * with lzo1x compression to maximize the amount of data that can
- * be packed into a physical page.
- *
- * Zv represents a PAM page with the index and object (plus a "size" value
- * necessary for decompression) immediately preceding the compressed data.
- */
-
-#define ZVH_SENTINEL  0x43214321
-
-struct zv_hdr {
-       uint32_t pool_id;
-       struct tmem_oid oid;
-       uint32_t index;
-       DECL_SENTINEL
-};
-
-static const int zv_max_page_size = (PAGE_SIZE / 8) * 7;
-
-static struct zv_hdr *zv_create(struct xv_pool *xvpool, uint32_t pool_id,
-                               struct tmem_oid *oid, uint32_t index,
-                               void *cdata, unsigned clen)
-{
-       struct page *page;
-       struct zv_hdr *zv = NULL;
-       uint32_t offset;
-       int ret;
-
-       BUG_ON(!irqs_disabled());
-       ret = xv_malloc(xvpool, clen + sizeof(struct zv_hdr),
-                       &page, &offset, ZCACHE_GFP_MASK);
-       if (unlikely(ret))
-               goto out;
-       zv = kmap_atomic(page, KM_USER0) + offset;
-       zv->index = index;
-       zv->oid = *oid;
-       zv->pool_id = pool_id;
-       SET_SENTINEL(zv, ZVH);
-       memcpy((char *)zv + sizeof(struct zv_hdr), cdata, clen);
-       kunmap_atomic(zv, KM_USER0);
-out:
-       return zv;
-}
-
-static void zv_free(struct xv_pool *xvpool, struct zv_hdr *zv)
-{
-       unsigned long flags;
-       struct page *page;
-       uint32_t offset;
-       uint16_t size;
-
-       ASSERT_SENTINEL(zv, ZVH);
-       size = xv_get_object_size(zv) - sizeof(*zv);
-       BUG_ON(size == 0 || size > zv_max_page_size);
-       INVERT_SENTINEL(zv, ZVH);
-       page = virt_to_page(zv);
-       offset = (unsigned long)zv & ~PAGE_MASK;
-       local_irq_save(flags);
-       xv_free(xvpool, page, offset);
-       local_irq_restore(flags);
-}
-
-static void zv_decompress(struct page *page, struct zv_hdr *zv)
-{
-       size_t clen = PAGE_SIZE;
-       char *to_va;
-       unsigned size;
-       int ret;
-
-       ASSERT_SENTINEL(zv, ZVH);
-       size = xv_get_object_size(zv) - sizeof(*zv);
-       BUG_ON(size == 0 || size > zv_max_page_size);
-       to_va = kmap_atomic(page, KM_USER0);
-       ret = lzo1x_decompress_safe((char *)zv + sizeof(*zv),
-                                       size, to_va, &clen);
-       kunmap_atomic(to_va, KM_USER0);
-       BUG_ON(ret != LZO_E_OK);
-       BUG_ON(clen != PAGE_SIZE);
-}
-
-/*
- * zcache core code starts here
- */
-
-/* useful stats not collected by cleancache or frontswap */
-static unsigned long zcache_flush_total;
-static unsigned long zcache_flush_found;
-static unsigned long zcache_flobj_total;
-static unsigned long zcache_flobj_found;
-static unsigned long zcache_failed_eph_puts;
-static unsigned long zcache_failed_pers_puts;
-
-#define MAX_POOLS_PER_CLIENT 16
-
-static struct {
-       struct tmem_pool *tmem_pools[MAX_POOLS_PER_CLIENT];
-       struct xv_pool *xvpool;
-} zcache_client;
-
-/*
- * Tmem operations assume the poolid implies the invoking client.
- * Zcache only has one client (the kernel itself), so translate
- * the poolid into the tmem_pool allocated for it.  A KVM version
- * of zcache would have one client per guest and each client might
- * have a poolid==N.
- */
-static struct tmem_pool *zcache_get_pool_by_id(uint32_t poolid)
-{
-       struct tmem_pool *pool = NULL;
-
-       if (poolid >= 0) {
-               pool = zcache_client.tmem_pools[poolid];
-               if (pool != NULL)
-                       atomic_inc(&pool->refcount);
-       }
-       return pool;
-}
-
-static void zcache_put_pool(struct tmem_pool *pool)
-{
-       if (pool != NULL)
-               atomic_dec(&pool->refcount);
-}
-
-/* counters for debugging */
-static unsigned long zcache_failed_get_free_pages;
-static unsigned long zcache_failed_alloc;
-static unsigned long zcache_put_to_flush;
-static unsigned long zcache_aborted_preload;
-static unsigned long zcache_aborted_shrink;
-
-/*
- * Ensure that memory allocation requests in zcache don't result
- * in direct reclaim requests via the shrinker, which would cause
- * an infinite loop.  Maybe a GFP flag would be better?
- */
-static DEFINE_SPINLOCK(zcache_direct_reclaim_lock);
-
-/*
- * for now, used named slabs so can easily track usage; later can
- * either just use kmalloc, or perhaps add a slab-like allocator
- * to more carefully manage total memory utilization
- */
-static struct kmem_cache *zcache_objnode_cache;
-static struct kmem_cache *zcache_obj_cache;
-static atomic_t zcache_curr_obj_count = ATOMIC_INIT(0);
-static unsigned long zcache_curr_obj_count_max;
-static atomic_t zcache_curr_objnode_count = ATOMIC_INIT(0);
-static unsigned long zcache_curr_objnode_count_max;
-
-/*
- * to avoid memory allocation recursion (e.g. due to direct reclaim), we
- * preload all necessary data structures so the hostops callbacks never
- * actually do a malloc
- */
-struct zcache_preload {
-       void *page;
-       struct tmem_obj *obj;
-       int nr;
-       struct tmem_objnode *objnodes[OBJNODE_TREE_MAX_PATH];
-};
-static DEFINE_PER_CPU(struct zcache_preload, zcache_preloads) = { 0, };
-
-static int zcache_do_preload(struct tmem_pool *pool)
-{
-       struct zcache_preload *kp;
-       struct tmem_objnode *objnode;
-       struct tmem_obj *obj;
-       void *page;
-       int ret = -ENOMEM;
-
-       if (unlikely(zcache_objnode_cache == NULL))
-               goto out;
-       if (unlikely(zcache_obj_cache == NULL))
-               goto out;
-       if (!spin_trylock(&zcache_direct_reclaim_lock)) {
-               zcache_aborted_preload++;
-               goto out;
-       }
-       preempt_disable();
-       kp = &__get_cpu_var(zcache_preloads);
-       while (kp->nr < ARRAY_SIZE(kp->objnodes)) {
-               preempt_enable_no_resched();
-               objnode = kmem_cache_alloc(zcache_objnode_cache,
-                               ZCACHE_GFP_MASK);
-               if (unlikely(objnode == NULL)) {
-                       zcache_failed_alloc++;
-                       goto unlock_out;
-               }
-               preempt_disable();
-               kp = &__get_cpu_var(zcache_preloads);
-               if (kp->nr < ARRAY_SIZE(kp->objnodes))
-                       kp->objnodes[kp->nr++] = objnode;
-               else
-                       kmem_cache_free(zcache_objnode_cache, objnode);
-       }
-       preempt_enable_no_resched();
-       obj = kmem_cache_alloc(zcache_obj_cache, ZCACHE_GFP_MASK);
-       if (unlikely(obj == NULL)) {
-               zcache_failed_alloc++;
-               goto unlock_out;
-       }
-       page = (void *)__get_free_page(ZCACHE_GFP_MASK);
-       if (unlikely(page == NULL)) {
-               zcache_failed_get_free_pages++;
-               kmem_cache_free(zcache_obj_cache, obj);
-               goto unlock_out;
-       }
-       preempt_disable();
-       kp = &__get_cpu_var(zcache_preloads);
-       if (kp->obj == NULL)
-               kp->obj = obj;
-       else
-               kmem_cache_free(zcache_obj_cache, obj);
-       if (kp->page == NULL)
-               kp->page = page;
-       else
-               free_page((unsigned long)page);
-       ret = 0;
-unlock_out:
-       spin_unlock(&zcache_direct_reclaim_lock);
-out:
-       return ret;
-}
-
-static void *zcache_get_free_page(void)
-{
-       struct zcache_preload *kp;
-       void *page;
-
-       kp = &__get_cpu_var(zcache_preloads);
-       page = kp->page;
-       BUG_ON(page == NULL);
-       kp->page = NULL;
-       return page;
-}
-
-static void zcache_free_page(void *p)
-{
-       free_page((unsigned long)p);
-}
-
-/*
- * zcache implementation for tmem host ops
- */
-
-static struct tmem_objnode *zcache_objnode_alloc(struct tmem_pool *pool)
-{
-       struct tmem_objnode *objnode = NULL;
-       unsigned long count;
-       struct zcache_preload *kp;
-
-       kp = &__get_cpu_var(zcache_preloads);
-       if (kp->nr <= 0)
-               goto out;
-       objnode = kp->objnodes[kp->nr - 1];
-       BUG_ON(objnode == NULL);
-       kp->objnodes[kp->nr - 1] = NULL;
-       kp->nr--;
-       count = atomic_inc_return(&zcache_curr_objnode_count);
-       if (count > zcache_curr_objnode_count_max)
-               zcache_curr_objnode_count_max = count;
-out:
-       return objnode;
-}
-
-static void zcache_objnode_free(struct tmem_objnode *objnode,
-                                       struct tmem_pool *pool)
-{
-       atomic_dec(&zcache_curr_objnode_count);
-       BUG_ON(atomic_read(&zcache_curr_objnode_count) < 0);
-       kmem_cache_free(zcache_objnode_cache, objnode);
-}
-
-static struct tmem_obj *zcache_obj_alloc(struct tmem_pool *pool)
-{
-       struct tmem_obj *obj = NULL;
-       unsigned long count;
-       struct zcache_preload *kp;
-
-       kp = &__get_cpu_var(zcache_preloads);
-       obj = kp->obj;
-       BUG_ON(obj == NULL);
-       kp->obj = NULL;
-       count = atomic_inc_return(&zcache_curr_obj_count);
-       if (count > zcache_curr_obj_count_max)
-               zcache_curr_obj_count_max = count;
-       return obj;
-}
-
-static void zcache_obj_free(struct tmem_obj *obj, struct tmem_pool *pool)
-{
-       atomic_dec(&zcache_curr_obj_count);
-       BUG_ON(atomic_read(&zcache_curr_obj_count) < 0);
-       kmem_cache_free(zcache_obj_cache, obj);
-}
-
-static struct tmem_hostops zcache_hostops = {
-       .obj_alloc = zcache_obj_alloc,
-       .obj_free = zcache_obj_free,
-       .objnode_alloc = zcache_objnode_alloc,
-       .objnode_free = zcache_objnode_free,
-};
-
-/*
- * zcache implementations for PAM page descriptor ops
- */
-
-static atomic_t zcache_curr_eph_pampd_count = ATOMIC_INIT(0);
-static unsigned long zcache_curr_eph_pampd_count_max;
-static atomic_t zcache_curr_pers_pampd_count = ATOMIC_INIT(0);
-static unsigned long zcache_curr_pers_pampd_count_max;
-
-/* forward reference */
-static int zcache_compress(struct page *from, void **out_va, size_t *out_len);
-
-static void *zcache_pampd_create(struct tmem_pool *pool, struct tmem_oid *oid,
-                                uint32_t index, struct page *page)
-{
-       void *pampd = NULL, *cdata;
-       size_t clen;
-       int ret;
-       bool ephemeral = is_ephemeral(pool);
-       unsigned long count;
-
-       if (ephemeral) {
-               ret = zcache_compress(page, &cdata, &clen);
-               if (ret == 0)
-
-                       goto out;
-               if (clen == 0 || clen > zbud_max_buddy_size()) {
-                       zcache_compress_poor++;
-                       goto out;
-               }
-               pampd = (void *)zbud_create(pool->pool_id, oid, index,
-                                               page, cdata, clen);
-               if (pampd != NULL) {
-                       count = atomic_inc_return(&zcache_curr_eph_pampd_count);
-                       if (count > zcache_curr_eph_pampd_count_max)
-                               zcache_curr_eph_pampd_count_max = count;
-               }
-       } else {
-               /*
-                * FIXME: This is all the "policy" there is for now.
-                * 3/4 totpages should allow ~37% of RAM to be filled with
-                * compressed frontswap pages
-                */
-               if (atomic_read(&zcache_curr_pers_pampd_count) >
-                                                       3 * totalram_pages / 4)
-                       goto out;
-               ret = zcache_compress(page, &cdata, &clen);
-               if (ret == 0)
-                       goto out;
-               if (clen > zv_max_page_size) {
-                       zcache_compress_poor++;
-                       goto out;
-               }
-               pampd = (void *)zv_create(zcache_client.xvpool, pool->pool_id,
-                                               oid, index, cdata, clen);
-               if (pampd == NULL)
-                       goto out;
-               count = atomic_inc_return(&zcache_curr_pers_pampd_count);
-               if (count > zcache_curr_pers_pampd_count_max)
-                       zcache_curr_pers_pampd_count_max = count;
-       }
-out:
-       return pampd;
-}
-
-/*
- * fill the pageframe corresponding to the struct page with the data
- * from the passed pampd
- */
-static int zcache_pampd_get_data(struct page *page, void *pampd,
-                                               struct tmem_pool *pool)
-{
-       int ret = 0;
-
-       if (is_ephemeral(pool))
-               ret = zbud_decompress(page, pampd);
-       else
-               zv_decompress(page, pampd);
-       return ret;
-}
-
-/*
- * free the pampd and remove it from any zcache lists
- * pampd must no longer be pointed to from any tmem data structures!
- */
-static void zcache_pampd_free(void *pampd, struct tmem_pool *pool)
-{
-       if (is_ephemeral(pool)) {
-               zbud_free_and_delist((struct zbud_hdr *)pampd);
-               atomic_dec(&zcache_curr_eph_pampd_count);
-               BUG_ON(atomic_read(&zcache_curr_eph_pampd_count) < 0);
-       } else {
-               zv_free(zcache_client.xvpool, (struct zv_hdr *)pampd);
-               atomic_dec(&zcache_curr_pers_pampd_count);
-               BUG_ON(atomic_read(&zcache_curr_pers_pampd_count) < 0);
-       }
-}
-
-static struct tmem_pamops zcache_pamops = {
-       .create = zcache_pampd_create,
-       .get_data = zcache_pampd_get_data,
-       .free = zcache_pampd_free,
-};
-
-/*
- * zcache compression/decompression and related per-cpu stuff
- */
-
-#define LZO_WORKMEM_BYTES LZO1X_1_MEM_COMPRESS
-#define LZO_DSTMEM_PAGE_ORDER 1
-static DEFINE_PER_CPU(unsigned char *, zcache_workmem);
-static DEFINE_PER_CPU(unsigned char *, zcache_dstmem);
-
-static int zcache_compress(struct page *from, void **out_va, size_t *out_len)
-{
-       int ret = 0;
-       unsigned char *dmem = __get_cpu_var(zcache_dstmem);
-       unsigned char *wmem = __get_cpu_var(zcache_workmem);
-       char *from_va;
-
-       BUG_ON(!irqs_disabled());
-       if (unlikely(dmem == NULL || wmem == NULL))
-               goto out;  /* no buffer, so can't compress */
-       from_va = kmap_atomic(from, KM_USER0);
-       mb();
-       ret = lzo1x_1_compress(from_va, PAGE_SIZE, dmem, out_len, wmem);
-       BUG_ON(ret != LZO_E_OK);
-       *out_va = dmem;
-       kunmap_atomic(from_va, KM_USER0);
-       ret = 1;
-out:
-       return ret;
-}
-
-
-static int zcache_cpu_notifier(struct notifier_block *nb,
-                               unsigned long action, void *pcpu)
-{
-       int cpu = (long)pcpu;
-       struct zcache_preload *kp;
-
-       switch (action) {
-       case CPU_UP_PREPARE:
-               per_cpu(zcache_dstmem, cpu) = (void *)__get_free_pages(
-                       GFP_KERNEL | __GFP_REPEAT,
-                       LZO_DSTMEM_PAGE_ORDER),
-               per_cpu(zcache_workmem, cpu) =
-                       kzalloc(LZO1X_MEM_COMPRESS,
-                               GFP_KERNEL | __GFP_REPEAT);
-               break;
-       case CPU_DEAD:
-       case CPU_UP_CANCELED:
-               free_pages((unsigned long)per_cpu(zcache_dstmem, cpu),
-                               LZO_DSTMEM_PAGE_ORDER);
-               per_cpu(zcache_dstmem, cpu) = NULL;
-               kfree(per_cpu(zcache_workmem, cpu));
-               per_cpu(zcache_workmem, cpu) = NULL;
-               kp = &per_cpu(zcache_preloads, cpu);
-               while (kp->nr) {
-                       kmem_cache_free(zcache_objnode_cache,
-                                       kp->objnodes[kp->nr - 1]);
-                       kp->objnodes[kp->nr - 1] = NULL;
-                       kp->nr--;
-               }
-               kmem_cache_free(zcache_obj_cache, kp->obj);
-               free_page((unsigned long)kp->page);
-               break;
-       default:
-               break;
-       }
-       return NOTIFY_OK;
-}
-
-static struct notifier_block zcache_cpu_notifier_block = {
-       .notifier_call = zcache_cpu_notifier
-};
-
-#ifdef CONFIG_SYSFS
-#define ZCACHE_SYSFS_RO(_name) \
-       static ssize_t zcache_##_name##_show(struct kobject *kobj, \
-                               struct kobj_attribute *attr, char *buf) \
-       { \
-               return sprintf(buf, "%lu\n", zcache_##_name); \
-       } \
-       static struct kobj_attribute zcache_##_name##_attr = { \
-               .attr = { .name = __stringify(_name), .mode = 0444 }, \
-               .show = zcache_##_name##_show, \
-       }
-
-#define ZCACHE_SYSFS_RO_ATOMIC(_name) \
-       static ssize_t zcache_##_name##_show(struct kobject *kobj, \
-                               struct kobj_attribute *attr, char *buf) \
-       { \
-           return sprintf(buf, "%d\n", atomic_read(&zcache_##_name)); \
-       } \
-       static struct kobj_attribute zcache_##_name##_attr = { \
-               .attr = { .name = __stringify(_name), .mode = 0444 }, \
-               .show = zcache_##_name##_show, \
-       }
-
-#define ZCACHE_SYSFS_RO_CUSTOM(_name, _func) \
-       static ssize_t zcache_##_name##_show(struct kobject *kobj, \
-                               struct kobj_attribute *attr, char *buf) \
-       { \
-           return _func(buf); \
-       } \
-       static struct kobj_attribute zcache_##_name##_attr = { \
-               .attr = { .name = __stringify(_name), .mode = 0444 }, \
-               .show = zcache_##_name##_show, \
-       }
-
-ZCACHE_SYSFS_RO(curr_obj_count_max);
-ZCACHE_SYSFS_RO(curr_objnode_count_max);
-ZCACHE_SYSFS_RO(flush_total);
-ZCACHE_SYSFS_RO(flush_found);
-ZCACHE_SYSFS_RO(flobj_total);
-ZCACHE_SYSFS_RO(flobj_found);
-ZCACHE_SYSFS_RO(failed_eph_puts);
-ZCACHE_SYSFS_RO(failed_pers_puts);
-ZCACHE_SYSFS_RO(zbud_curr_zbytes);
-ZCACHE_SYSFS_RO(zbud_cumul_zpages);
-ZCACHE_SYSFS_RO(zbud_cumul_zbytes);
-ZCACHE_SYSFS_RO(zbud_buddied_count);
-ZCACHE_SYSFS_RO(zbpg_unused_list_count);
-ZCACHE_SYSFS_RO(evicted_raw_pages);
-ZCACHE_SYSFS_RO(evicted_unbuddied_pages);
-ZCACHE_SYSFS_RO(evicted_buddied_pages);
-ZCACHE_SYSFS_RO(failed_get_free_pages);
-ZCACHE_SYSFS_RO(failed_alloc);
-ZCACHE_SYSFS_RO(put_to_flush);
-ZCACHE_SYSFS_RO(aborted_preload);
-ZCACHE_SYSFS_RO(aborted_shrink);
-ZCACHE_SYSFS_RO(compress_poor);
-ZCACHE_SYSFS_RO_ATOMIC(zbud_curr_raw_pages);
-ZCACHE_SYSFS_RO_ATOMIC(zbud_curr_zpages);
-ZCACHE_SYSFS_RO_ATOMIC(curr_obj_count);
-ZCACHE_SYSFS_RO_ATOMIC(curr_objnode_count);
-ZCACHE_SYSFS_RO_CUSTOM(zbud_unbuddied_list_counts,
-                       zbud_show_unbuddied_list_counts);
-ZCACHE_SYSFS_RO_CUSTOM(zbud_cumul_chunk_counts,
-                       zbud_show_cumul_chunk_counts);
-
-static struct attribute *zcache_attrs[] = {
-       &zcache_curr_obj_count_attr.attr,
-       &zcache_curr_obj_count_max_attr.attr,
-       &zcache_curr_objnode_count_attr.attr,
-       &zcache_curr_objnode_count_max_attr.attr,
-       &zcache_flush_total_attr.attr,
-       &zcache_flobj_total_attr.attr,
-       &zcache_flush_found_attr.attr,
-       &zcache_flobj_found_attr.attr,
-       &zcache_failed_eph_puts_attr.attr,
-       &zcache_failed_pers_puts_attr.attr,
-       &zcache_compress_poor_attr.attr,
-       &zcache_zbud_curr_raw_pages_attr.attr,
-       &zcache_zbud_curr_zpages_attr.attr,
-       &zcache_zbud_curr_zbytes_attr.attr,
-       &zcache_zbud_cumul_zpages_attr.attr,
-       &zcache_zbud_cumul_zbytes_attr.attr,
-       &zcache_zbud_buddied_count_attr.attr,
-       &zcache_zbpg_unused_list_count_attr.attr,
-       &zcache_evicted_raw_pages_attr.attr,
-       &zcache_evicted_unbuddied_pages_attr.attr,
-       &zcache_evicted_buddied_pages_attr.attr,
-       &zcache_failed_get_free_pages_attr.attr,
-       &zcache_failed_alloc_attr.attr,
-       &zcache_put_to_flush_attr.attr,
-       &zcache_aborted_preload_attr.attr,
-       &zcache_aborted_shrink_attr.attr,
-       &zcache_zbud_unbuddied_list_counts_attr.attr,
-       &zcache_zbud_cumul_chunk_counts_attr.attr,
-       NULL,
-};
-
-static struct attribute_group zcache_attr_group = {
-       .attrs = zcache_attrs,
-       .name = "zcache",
-};
-
-#endif /* CONFIG_SYSFS */
-/*
- * When zcache is disabled ("frozen"), pools can be created and destroyed,
- * but all puts (and thus all other operations that require memory allocation)
- * must fail.  If zcache is unfrozen, accepts puts, then frozen again,
- * data consistency requires all puts while frozen to be converted into
- * flushes.
- */
-static bool zcache_freeze;
-
-/*
- * zcache shrinker interface (only useful for ephemeral pages, so zbud only)
- */
-static int shrink_zcache_memory(struct shrinker *shrink,
-                               struct shrink_control *sc)
-{
-       int ret = -1;
-       int nr = sc->nr_to_scan;
-       gfp_t gfp_mask = sc->gfp_mask;
-
-       if (nr >= 0) {
-               if (!(gfp_mask & __GFP_FS))
-                       /* does this case really need to be skipped? */
-                       goto out;
-               if (spin_trylock(&zcache_direct_reclaim_lock)) {
-                       zbud_evict_pages(nr);
-                       spin_unlock(&zcache_direct_reclaim_lock);
-               } else
-                       zcache_aborted_shrink++;
-       }
-       ret = (int)atomic_read(&zcache_zbud_curr_raw_pages);
-out:
-       return ret;
-}
-
-static struct shrinker zcache_shrinker = {
-       .shrink = shrink_zcache_memory,
-       .seeks = DEFAULT_SEEKS,
-};
-
-/*
- * zcache shims between cleancache/frontswap ops and tmem
- */
-
-static int zcache_put_page(int pool_id, struct tmem_oid *oidp,
-                               uint32_t index, struct page *page)
-{
-       struct tmem_pool *pool;
-       int ret = -1;
-
-       BUG_ON(!irqs_disabled());
-       pool = zcache_get_pool_by_id(pool_id);
-       if (unlikely(pool == NULL))
-               goto out;
-       if (!zcache_freeze && zcache_do_preload(pool) == 0) {
-               /* preload does preempt_disable on success */
-               ret = tmem_put(pool, oidp, index, page);
-               if (ret < 0) {
-                       if (is_ephemeral(pool))
-                               zcache_failed_eph_puts++;
-                       else
-                               zcache_failed_pers_puts++;
-               }
-               zcache_put_pool(pool);
-               preempt_enable_no_resched();
-       } else {
-               zcache_put_to_flush++;
-               if (atomic_read(&pool->obj_count) > 0)
-                       /* the put fails whether the flush succeeds or not */
-                       (void)tmem_flush_page(pool, oidp, index);
-               zcache_put_pool(pool);
-       }
-out:
-       return ret;
-}
-
-static int zcache_get_page(int pool_id, struct tmem_oid *oidp,
-                               uint32_t index, struct page *page)
-{
-       struct tmem_pool *pool;
-       int ret = -1;
-       unsigned long flags;
-
-       local_irq_save(flags);
-       pool = zcache_get_pool_by_id(pool_id);
-       if (likely(pool != NULL)) {
-               if (atomic_read(&pool->obj_count) > 0)
-                       ret = tmem_get(pool, oidp, index, page);
-               zcache_put_pool(pool);
-       }
-       local_irq_restore(flags);
-       return ret;
-}
-
-static int zcache_flush_page(int pool_id, struct tmem_oid *oidp, uint32_t index)
-{
-       struct tmem_pool *pool;
-       int ret = -1;
-       unsigned long flags;
-
-       local_irq_save(flags);
-       zcache_flush_total++;
-       pool = zcache_get_pool_by_id(pool_id);
-       if (likely(pool != NULL)) {
-               if (atomic_read(&pool->obj_count) > 0)
-                       ret = tmem_flush_page(pool, oidp, index);
-               zcache_put_pool(pool);
-       }
-       if (ret >= 0)
-               zcache_flush_found++;
-       local_irq_restore(flags);
-       return ret;
-}
-
-static int zcache_flush_object(int pool_id, struct tmem_oid *oidp)
-{
-       struct tmem_pool *pool;
-       int ret = -1;
-       unsigned long flags;
-
-       local_irq_save(flags);
-       zcache_flobj_total++;
-       pool = zcache_get_pool_by_id(pool_id);
-       if (likely(pool != NULL)) {
-               if (atomic_read(&pool->obj_count) > 0)
-                       ret = tmem_flush_object(pool, oidp);
-               zcache_put_pool(pool);
-       }
-       if (ret >= 0)
-               zcache_flobj_found++;
-       local_irq_restore(flags);
-       return ret;
-}
-
-static int zcache_destroy_pool(int pool_id)
-{
-       struct tmem_pool *pool = NULL;
-       int ret = -1;
-
-       if (pool_id < 0)
-               goto out;
-       pool = zcache_client.tmem_pools[pool_id];
-       if (pool == NULL)
-               goto out;
-       zcache_client.tmem_pools[pool_id] = NULL;
-       /* wait for pool activity on other cpus to quiesce */
-       while (atomic_read(&pool->refcount) != 0)
-               ;
-       local_bh_disable();
-       ret = tmem_destroy_pool(pool);
-       local_bh_enable();
-       kfree(pool);
-       pr_info("zcache: destroyed pool id=%d\n", pool_id);
-out:
-       return ret;
-}
-
-static int zcache_new_pool(uint32_t flags)
-{
-       int poolid = -1;
-       struct tmem_pool *pool;
-
-       pool = kmalloc(sizeof(struct tmem_pool), GFP_KERNEL);
-       if (pool == NULL) {
-               pr_info("zcache: pool creation failed: out of memory\n");
-               goto out;
-       }
-
-       for (poolid = 0; poolid < MAX_POOLS_PER_CLIENT; poolid++)
-               if (zcache_client.tmem_pools[poolid] == NULL)
-                       break;
-       if (poolid >= MAX_POOLS_PER_CLIENT) {
-               pr_info("zcache: pool creation failed: max exceeded\n");
-               kfree(pool);
-               poolid = -1;
-               goto out;
-       }
-       atomic_set(&pool->refcount, 0);
-       pool->client = &zcache_client;
-       pool->pool_id = poolid;
-       tmem_new_pool(pool, flags);
-       zcache_client.tmem_pools[poolid] = pool;
-       pr_info("zcache: created %s tmem pool, id=%d\n",
-               flags & TMEM_POOL_PERSIST ? "persistent" : "ephemeral",
-               poolid);
-out:
-       return poolid;
-}
-
-/**********
- * Two kernel functionalities currently can be layered on top of tmem.
- * These are "cleancache" which is used as a second-chance cache for clean
- * page cache pages; and "frontswap" which is used for swap pages
- * to avoid writes to disk.  A generic "shim" is provided here for each
- * to translate in-kernel semantics to zcache semantics.
- */
-
-#ifdef CONFIG_CLEANCACHE
-static void zcache_cleancache_put_page(int pool_id,
-                                       struct cleancache_filekey key,
-                                       pgoff_t index, struct page *page)
-{
-       u32 ind = (u32) index;
-       struct tmem_oid oid = *(struct tmem_oid *)&key;
-
-       if (likely(ind == index))
-               (void)zcache_put_page(pool_id, &oid, index, page);
-}
-
-static int zcache_cleancache_get_page(int pool_id,
-                                       struct cleancache_filekey key,
-                                       pgoff_t index, struct page *page)
-{
-       u32 ind = (u32) index;
-       struct tmem_oid oid = *(struct tmem_oid *)&key;
-       int ret = -1;
-
-       if (likely(ind == index))
-               ret = zcache_get_page(pool_id, &oid, index, page);
-       return ret;
-}
-
-static void zcache_cleancache_flush_page(int pool_id,
-                                       struct cleancache_filekey key,
-                                       pgoff_t index)
-{
-       u32 ind = (u32) index;
-       struct tmem_oid oid = *(struct tmem_oid *)&key;
-
-       if (likely(ind == index))
-               (void)zcache_flush_page(pool_id, &oid, ind);
-}
-
-static void zcache_cleancache_flush_inode(int pool_id,
-                                       struct cleancache_filekey key)
-{
-       struct tmem_oid oid = *(struct tmem_oid *)&key;
-
-       (void)zcache_flush_object(pool_id, &oid);
-}
-
-static void zcache_cleancache_flush_fs(int pool_id)
-{
-       if (pool_id >= 0)
-               (void)zcache_destroy_pool(pool_id);
-}
-
-static int zcache_cleancache_init_fs(size_t pagesize)
-{
-       BUG_ON(sizeof(struct cleancache_filekey) !=
-                               sizeof(struct tmem_oid));
-       BUG_ON(pagesize != PAGE_SIZE);
-       return zcache_new_pool(0);
-}
-
-static int zcache_cleancache_init_shared_fs(char *uuid, size_t pagesize)
-{
-       /* shared pools are unsupported and map to private */
-       BUG_ON(sizeof(struct cleancache_filekey) !=
-                               sizeof(struct tmem_oid));
-       BUG_ON(pagesize != PAGE_SIZE);
-       return zcache_new_pool(0);
-}
-
-static struct cleancache_ops zcache_cleancache_ops = {
-       .put_page = zcache_cleancache_put_page,
-       .get_page = zcache_cleancache_get_page,
-       .flush_page = zcache_cleancache_flush_page,
-       .flush_inode = zcache_cleancache_flush_inode,
-       .flush_fs = zcache_cleancache_flush_fs,
-       .init_shared_fs = zcache_cleancache_init_shared_fs,
-       .init_fs = zcache_cleancache_init_fs
-};
-
-struct cleancache_ops zcache_cleancache_register_ops(void)
-{
-       struct cleancache_ops old_ops =
-               cleancache_register_ops(&zcache_cleancache_ops);
-
-       return old_ops;
-}
-#endif
-
-#ifdef CONFIG_FRONTSWAP
-/* a single tmem poolid is used for all frontswap "types" (swapfiles) */
-static int zcache_frontswap_poolid = -1;
-
-/*
- * Swizzling increases objects per swaptype, increasing tmem concurrency
- * for heavy swaploads.  Later, larger nr_cpus -> larger SWIZ_BITS
- */
-#define SWIZ_BITS              4
-#define SWIZ_MASK              ((1 << SWIZ_BITS) - 1)
-#define _oswiz(_type, _ind)    ((_type << SWIZ_BITS) | (_ind & SWIZ_MASK))
-#define iswiz(_ind)            (_ind >> SWIZ_BITS)
-
-static inline struct tmem_oid oswiz(unsigned type, u32 ind)
-{
-       struct tmem_oid oid = { .oid = { 0 } };
-       oid.oid[0] = _oswiz(type, ind);
-       return oid;
-}
-
-static int zcache_frontswap_put_page(unsigned type, pgoff_t offset,
-                                  struct page *page)
-{
-       u64 ind64 = (u64)offset;
-       u32 ind = (u32)offset;
-       struct tmem_oid oid = oswiz(type, ind);
-       int ret = -1;
-       unsigned long flags;
-
-       BUG_ON(!PageLocked(page));
-       if (likely(ind64 == ind)) {
-               local_irq_save(flags);
-               ret = zcache_put_page(zcache_frontswap_poolid, &oid,
-                                       iswiz(ind), page);
-               local_irq_restore(flags);
-       }
-       return ret;
-}
-
-/* returns 0 if the page was successfully gotten from frontswap, -1 if
- * was not present (should never happen!) */
-static int zcache_frontswap_get_page(unsigned type, pgoff_t offset,
-                                  struct page *page)
-{
-       u64 ind64 = (u64)offset;
-       u32 ind = (u32)offset;
-       struct tmem_oid oid = oswiz(type, ind);
-       int ret = -1;
-
-       BUG_ON(!PageLocked(page));
-       if (likely(ind64 == ind))
-               ret = zcache_get_page(zcache_frontswap_poolid, &oid,
-                                       iswiz(ind), page);
-       return ret;
-}
-
-/* flush a single page from frontswap */
-static void zcache_frontswap_flush_page(unsigned type, pgoff_t offset)
-{
-       u64 ind64 = (u64)offset;
-       u32 ind = (u32)offset;
-       struct tmem_oid oid = oswiz(type, ind);
-
-       if (likely(ind64 == ind))
-               (void)zcache_flush_page(zcache_frontswap_poolid, &oid,
-                                       iswiz(ind));
-}
-
-/* flush all pages from the passed swaptype */
-static void zcache_frontswap_flush_area(unsigned type)
-{
-       struct tmem_oid oid;
-       int ind;
-
-       for (ind = SWIZ_MASK; ind >= 0; ind--) {
-               oid = oswiz(type, ind);
-               (void)zcache_flush_object(zcache_frontswap_poolid, &oid);
-       }
-}
-
-static void zcache_frontswap_init(unsigned ignored)
-{
-       /* a single tmem poolid is used for all frontswap "types" (swapfiles) */
-       if (zcache_frontswap_poolid < 0)
-               zcache_frontswap_poolid = zcache_new_pool(TMEM_POOL_PERSIST);
-}
-
-static struct frontswap_ops zcache_frontswap_ops = {
-       .put_page = zcache_frontswap_put_page,
-       .get_page = zcache_frontswap_get_page,
-       .flush_page = zcache_frontswap_flush_page,
-       .flush_area = zcache_frontswap_flush_area,
-       .init = zcache_frontswap_init
-};
-
-struct frontswap_ops zcache_frontswap_register_ops(void)
-{
-       struct frontswap_ops old_ops =
-               frontswap_register_ops(&zcache_frontswap_ops);
-
-       return old_ops;
-}
-#endif
-
-/*
- * zcache initialization
- * NOTE FOR NOW zcache MUST BE PROVIDED AS A KERNEL BOOT PARAMETER OR
- * NOTHING HAPPENS!
- */
-
-static int zcache_enabled;
-
-static int __init enable_zcache(char *s)
-{
-       zcache_enabled = 1;
-       return 1;
-}
-__setup("zcache", enable_zcache);
-
-/* allow independent dynamic disabling of cleancache and frontswap */
-
-static int use_cleancache = 1;
-
-static int __init no_cleancache(char *s)
-{
-       use_cleancache = 0;
-       return 1;
-}
-
-__setup("nocleancache", no_cleancache);
-
-static int use_frontswap = 1;
-
-static int __init no_frontswap(char *s)
-{
-       use_frontswap = 0;
-       return 1;
-}
-
-__setup("nofrontswap", no_frontswap);
-
-static int __init zcache_init(void)
-{
-#ifdef CONFIG_SYSFS
-       int ret = 0;
-
-       ret = sysfs_create_group(mm_kobj, &zcache_attr_group);
-       if (ret) {
-               pr_err("zcache: can't create sysfs\n");
-               goto out;
-       }
-#endif /* CONFIG_SYSFS */
-#if defined(CONFIG_CLEANCACHE) || defined(CONFIG_FRONTSWAP)
-       if (zcache_enabled) {
-               unsigned int cpu;
-
-               tmem_register_hostops(&zcache_hostops);
-               tmem_register_pamops(&zcache_pamops);
-               ret = register_cpu_notifier(&zcache_cpu_notifier_block);
-               if (ret) {
-                       pr_err("zcache: can't register cpu notifier\n");
-                       goto out;
-               }
-               for_each_online_cpu(cpu) {
-                       void *pcpu = (void *)(long)cpu;
-                       zcache_cpu_notifier(&zcache_cpu_notifier_block,
-                               CPU_UP_PREPARE, pcpu);
-               }
-       }
-       zcache_objnode_cache = kmem_cache_create("zcache_objnode",
-                               sizeof(struct tmem_objnode), 0, 0, NULL);
-       zcache_obj_cache = kmem_cache_create("zcache_obj",
-                               sizeof(struct tmem_obj), 0, 0, NULL);
-#endif
-#ifdef CONFIG_CLEANCACHE
-       if (zcache_enabled && use_cleancache) {
-               struct cleancache_ops old_ops;
-
-               zbud_init();
-               register_shrinker(&zcache_shrinker);
-               old_ops = zcache_cleancache_register_ops();
-               pr_info("zcache: cleancache enabled using kernel "
-                       "transcendent memory and compression buddies\n");
-               if (old_ops.init_fs != NULL)
-                       pr_warning("zcache: cleancache_ops overridden");
-       }
-#endif
-#ifdef CONFIG_FRONTSWAP
-       if (zcache_enabled && use_frontswap) {
-               struct frontswap_ops old_ops;
-
-               zcache_client.xvpool = xv_create_pool();
-               if (zcache_client.xvpool == NULL) {
-                       pr_err("zcache: can't create xvpool\n");
-                       goto out;
-               }
-               old_ops = zcache_frontswap_register_ops();
-               pr_info("zcache: frontswap enabled using kernel "
-                       "transcendent memory and xvmalloc\n");
-               if (old_ops.init != NULL)
-                       pr_warning("ktmem: frontswap_ops overridden");
-       }
-#endif
-out:
-       return ret;
-}
-
-module_init(zcache_init)
diff --git a/drivers/staging/zcache/zcache_drv.c b/drivers/staging/zcache/zcache_drv.c
new file mode 100644
index 0000000..77ac2d4
--- /dev/null
+++ b/drivers/staging/zcache/zcache_drv.c
@@ -0,0 +1,1661 @@
+/*
+ * zcache.c
+ *
+ * Copyright (c) 2010,2011, Dan Magenheimer, Oracle Corp.
+ * Copyright (c) 2010,2011, Nitin Gupta
+ *
+ * Zcache provides an in-kernel "host implementation" for transcendent memory
+ * and, thus indirectly, for cleancache and frontswap.  Zcache includes two
+ * page-accessible memory [1] interfaces, both utilizing lzo1x compression:
+ * 1) "compression buddies" ("zbud") is used for ephemeral pages
+ * 2) xvmalloc is used for persistent pages.
+ * Xvmalloc (based on the TLSF allocator) has very low fragmentation
+ * so maximizes space efficiency, while zbud allows pairs (and potentially,
+ * in the future, more than a pair of) compressed pages to be closely linked
+ * so that reclaiming can be done via the kernel's physical-page-oriented
+ * "shrinker" interface.
+ *
+ * [1] For a definition of page-accessible memory (aka PAM), see:
+ *   http://marc.info/?l=linux-mm&m=127811271605009
+ */
+
+#include <linux/cpu.h>
+#include <linux/highmem.h>
+#include <linux/list.h>
+#include <linux/lzo.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/types.h>
+#include <linux/atomic.h>
+#include "tmem.h"
+
+#include "../zram/xvmalloc.h" /* if built in drivers/staging */
+
+#if (!defined(CONFIG_CLEANCACHE) && !defined(CONFIG_FRONTSWAP))
+#error "zcache is useless without CONFIG_CLEANCACHE or CONFIG_FRONTSWAP"
+#endif
+#ifdef CONFIG_CLEANCACHE
+#include <linux/cleancache.h>
+#endif
+#ifdef CONFIG_FRONTSWAP
+#include <linux/frontswap.h>
+#endif
+
+#if 0
+/* this is more aggressive but may cause other problems? */
+#define ZCACHE_GFP_MASK        (GFP_ATOMIC | __GFP_NORETRY | __GFP_NOWARN)
+#else
+#define ZCACHE_GFP_MASK \
+       (__GFP_FS | __GFP_NORETRY | __GFP_NOWARN | __GFP_NOMEMALLOC)
+#endif
+
+/**********
+ * Compression buddies ("zbud") provides for packing two (or, possibly
+ * in the future, more) compressed ephemeral pages into a single "raw"
+ * (physical) page and tracking them with data structures so that
+ * the raw pages can be easily reclaimed.
+ *
+ * A zbud page ("zbpg") is an aligned page containing a list_head,
+ * a lock, and two "zbud headers".  The remainder of the physical
+ * page is divided up into aligned 64-byte "chunks" which contain
+ * the compressed data for zero, one, or two zbuds.  Each zbpg
+ * resides on: (1) an "unused list" if it has no zbuds; (2) a
+ * "buddied" list if it is fully populated  with two zbuds; or
+ * (3) one of PAGE_SIZE/64 "unbuddied" lists indexed by how many chunks
+ * the one unbuddied zbud uses.  The data inside a zbpg cannot be
+ * read or written unless the zbpg's lock is held.
+ */
+
+#define ZBH_SENTINEL  0x43214321
+#define ZBPG_SENTINEL  0xdeadbeef
+
+#define ZBUD_MAX_BUDS 2
+
+struct zbud_hdr {
+       uint32_t pool_id;
+       struct tmem_oid oid;
+       uint32_t index;
+       uint16_t size; /* compressed size in bytes, zero means unused */
+       DECL_SENTINEL
+};
+
+struct zbud_page {
+       struct list_head bud_list;
+       spinlock_t lock;
+       struct zbud_hdr buddy[ZBUD_MAX_BUDS];
+       DECL_SENTINEL
+       /* followed by NUM_CHUNK aligned CHUNK_SIZE-byte chunks */
+};
+
+#define CHUNK_SHIFT    6
+#define CHUNK_SIZE     (1 << CHUNK_SHIFT)
+#define CHUNK_MASK     (~(CHUNK_SIZE-1))
+#define NCHUNKS                (((PAGE_SIZE - sizeof(struct zbud_page)) & \
+                               CHUNK_MASK) >> CHUNK_SHIFT)
+#define MAX_CHUNK      (NCHUNKS-1)
+
+static struct {
+       struct list_head list;
+       unsigned count;
+} zbud_unbuddied[NCHUNKS];
+/* list N contains pages with N chunks USED and NCHUNKS-N unused */
+/* element 0 is never used but optimizing that isn't worth it */
+static unsigned long zbud_cumul_chunk_counts[NCHUNKS];
+
+struct list_head zbud_buddied_list;
+static unsigned long zcache_zbud_buddied_count;
+
+/* protects the buddied list and all unbuddied lists */
+static DEFINE_SPINLOCK(zbud_budlists_spinlock);
+
+static LIST_HEAD(zbpg_unused_list);
+static unsigned long zcache_zbpg_unused_list_count;
+
+/* protects the unused page list */
+static DEFINE_SPINLOCK(zbpg_unused_list_spinlock);
+
+static atomic_t zcache_zbud_curr_raw_pages;
+static atomic_t zcache_zbud_curr_zpages;
+static unsigned long zcache_zbud_curr_zbytes;
+static unsigned long zcache_zbud_cumul_zpages;
+static unsigned long zcache_zbud_cumul_zbytes;
+static unsigned long zcache_compress_poor;
+
+/* forward references */
+static void *zcache_get_free_page(void);
+static void zcache_free_page(void *p);
+
+/*
+ * zbud helper functions
+ */
+
+static inline unsigned zbud_max_buddy_size(void)
+{
+       return MAX_CHUNK << CHUNK_SHIFT;
+}
+
+static inline unsigned zbud_size_to_chunks(unsigned size)
+{
+       BUG_ON(size == 0 || size > zbud_max_buddy_size());
+       return (size + CHUNK_SIZE - 1) >> CHUNK_SHIFT;
+}
+
+static inline int zbud_budnum(struct zbud_hdr *zh)
+{
+       unsigned offset = (unsigned long)zh & (PAGE_SIZE - 1);
+       struct zbud_page *zbpg = NULL;
+       unsigned budnum = -1U;
+       int i;
+
+       for (i = 0; i < ZBUD_MAX_BUDS; i++)
+               if (offset == offsetof(typeof(*zbpg), buddy[i])) {
+                       budnum = i;
+                       break;
+               }
+       BUG_ON(budnum == -1U);
+       return budnum;
+}
+
+static char *zbud_data(struct zbud_hdr *zh, unsigned size)
+{
+       struct zbud_page *zbpg;
+       char *p;
+       unsigned budnum;
+
+       ASSERT_SENTINEL(zh, ZBH);
+       budnum = zbud_budnum(zh);
+       BUG_ON(size == 0 || size > zbud_max_buddy_size());
+       zbpg = container_of(zh, struct zbud_page, buddy[budnum]);
+       ASSERT_SPINLOCK(&zbpg->lock);
+       p = (char *)zbpg;
+       if (budnum == 0)
+               p += ((sizeof(struct zbud_page) + CHUNK_SIZE - 1) &
+                                                       CHUNK_MASK);
+       else if (budnum == 1)
+               p += PAGE_SIZE - ((size + CHUNK_SIZE - 1) & CHUNK_MASK);
+       return p;
+}
+
+/*
+ * zbud raw page management
+ */
+
+static struct zbud_page *zbud_alloc_raw_page(void)
+{
+       struct zbud_page *zbpg = NULL;
+       struct zbud_hdr *zh0, *zh1;
+       bool recycled = 0;
+
+       /* if any pages on the zbpg list, use one */
+       spin_lock(&zbpg_unused_list_spinlock);
+       if (!list_empty(&zbpg_unused_list)) {
+               zbpg = list_first_entry(&zbpg_unused_list,
+                               struct zbud_page, bud_list);
+               list_del_init(&zbpg->bud_list);
+               zcache_zbpg_unused_list_count--;
+               recycled = 1;
+       }
+       spin_unlock(&zbpg_unused_list_spinlock);
+       if (zbpg == NULL)
+               /* none on zbpg list, try to get a kernel page */
+               zbpg = zcache_get_free_page();
+       if (likely(zbpg != NULL)) {
+               INIT_LIST_HEAD(&zbpg->bud_list);
+               zh0 = &zbpg->buddy[0]; zh1 = &zbpg->buddy[1];
+               spin_lock_init(&zbpg->lock);
+               if (recycled) {
+                       ASSERT_INVERTED_SENTINEL(zbpg, ZBPG);
+                       SET_SENTINEL(zbpg, ZBPG);
+                       BUG_ON(zh0->size != 0 || tmem_oid_valid(&zh0->oid));
+                       BUG_ON(zh1->size != 0 || tmem_oid_valid(&zh1->oid));
+               } else {
+                       atomic_inc(&zcache_zbud_curr_raw_pages);
+                       INIT_LIST_HEAD(&zbpg->bud_list);
+                       SET_SENTINEL(zbpg, ZBPG);
+                       zh0->size = 0; zh1->size = 0;
+                       tmem_oid_set_invalid(&zh0->oid);
+                       tmem_oid_set_invalid(&zh1->oid);
+               }
+       }
+       return zbpg;
+}
+
+static void zbud_free_raw_page(struct zbud_page *zbpg)
+{
+       struct zbud_hdr *zh0 = &zbpg->buddy[0], *zh1 = &zbpg->buddy[1];
+
+       ASSERT_SENTINEL(zbpg, ZBPG);
+       BUG_ON(!list_empty(&zbpg->bud_list));
+       ASSERT_SPINLOCK(&zbpg->lock);
+       BUG_ON(zh0->size != 0 || tmem_oid_valid(&zh0->oid));
+       BUG_ON(zh1->size != 0 || tmem_oid_valid(&zh1->oid));
+       INVERT_SENTINEL(zbpg, ZBPG);
+       spin_unlock(&zbpg->lock);
+       spin_lock(&zbpg_unused_list_spinlock);
+       list_add(&zbpg->bud_list, &zbpg_unused_list);
+       zcache_zbpg_unused_list_count++;
+       spin_unlock(&zbpg_unused_list_spinlock);
+}
+
+/*
+ * core zbud handling routines
+ */
+
+static unsigned zbud_free(struct zbud_hdr *zh)
+{
+       unsigned size;
+
+       ASSERT_SENTINEL(zh, ZBH);
+       BUG_ON(!tmem_oid_valid(&zh->oid));
+       size = zh->size;
+       BUG_ON(zh->size == 0 || zh->size > zbud_max_buddy_size());
+       zh->size = 0;
+       tmem_oid_set_invalid(&zh->oid);
+       INVERT_SENTINEL(zh, ZBH);
+       zcache_zbud_curr_zbytes -= size;
+       atomic_dec(&zcache_zbud_curr_zpages);
+       return size;
+}
+
+static void zbud_free_and_delist(struct zbud_hdr *zh)
+{
+       unsigned chunks;
+       struct zbud_hdr *zh_other;
+       unsigned budnum = zbud_budnum(zh), size;
+       struct zbud_page *zbpg =
+               container_of(zh, struct zbud_page, buddy[budnum]);
+
+       spin_lock(&zbpg->lock);
+       if (list_empty(&zbpg->bud_list)) {
+               /* ignore zombie page... see zbud_evict_pages() */
+               spin_unlock(&zbpg->lock);
+               return;
+       }
+       size = zbud_free(zh);
+       ASSERT_SPINLOCK(&zbpg->lock);
+       zh_other = &zbpg->buddy[(budnum == 0) ? 1 : 0];
+       if (zh_other->size == 0) { /* was unbuddied: unlist and free */
+               chunks = zbud_size_to_chunks(size) ;
+               spin_lock(&zbud_budlists_spinlock);
+               BUG_ON(list_empty(&zbud_unbuddied[chunks].list));
+               list_del_init(&zbpg->bud_list);
+               zbud_unbuddied[chunks].count--;
+               spin_unlock(&zbud_budlists_spinlock);
+               zbud_free_raw_page(zbpg);
+       } else { /* was buddied: move remaining buddy to unbuddied list */
+               chunks = zbud_size_to_chunks(zh_other->size) ;
+               spin_lock(&zbud_budlists_spinlock);
+               list_del_init(&zbpg->bud_list);
+               zcache_zbud_buddied_count--;
+               list_add_tail(&zbpg->bud_list, &zbud_unbuddied[chunks].list);
+               zbud_unbuddied[chunks].count++;
+               spin_unlock(&zbud_budlists_spinlock);
+               spin_unlock(&zbpg->lock);
+       }
+}
+
+static struct zbud_hdr *zbud_create(uint32_t pool_id, struct tmem_oid *oid,
+                                       uint32_t index, struct page *page,
+                                       void *cdata, unsigned size)
+{
+       struct zbud_hdr *zh0, *zh1, *zh = NULL;
+       struct zbud_page *zbpg = NULL, *ztmp;
+       unsigned nchunks;
+       char *to;
+       int i, found_good_buddy = 0;
+
+       nchunks = zbud_size_to_chunks(size) ;
+       for (i = MAX_CHUNK - nchunks + 1; i > 0; i--) {
+               spin_lock(&zbud_budlists_spinlock);
+               if (!list_empty(&zbud_unbuddied[i].list)) {
+                       list_for_each_entry_safe(zbpg, ztmp,
+                                   &zbud_unbuddied[i].list, bud_list) {
+                               if (spin_trylock(&zbpg->lock)) {
+                                       found_good_buddy = i;
+                                       goto found_unbuddied;
+                               }
+                       }
+               }
+               spin_unlock(&zbud_budlists_spinlock);
+       }
+       /* didn't find a good buddy, try allocating a new page */
+       zbpg = zbud_alloc_raw_page();
+       if (unlikely(zbpg == NULL))
+               goto out;
+       /* ok, have a page, now compress the data before taking locks */
+       spin_lock(&zbpg->lock);
+       spin_lock(&zbud_budlists_spinlock);
+       list_add_tail(&zbpg->bud_list, &zbud_unbuddied[nchunks].list);
+       zbud_unbuddied[nchunks].count++;
+       zh = &zbpg->buddy[0];
+       goto init_zh;
+
+found_unbuddied:
+       ASSERT_SPINLOCK(&zbpg->lock);
+       zh0 = &zbpg->buddy[0]; zh1 = &zbpg->buddy[1];
+       BUG_ON(!((zh0->size == 0) ^ (zh1->size == 0)));
+       if (zh0->size != 0) { /* buddy0 in use, buddy1 is vacant */
+               ASSERT_SENTINEL(zh0, ZBH);
+               zh = zh1;
+       } else if (zh1->size != 0) { /* buddy1 in use, buddy0 is vacant */
+               ASSERT_SENTINEL(zh1, ZBH);
+               zh = zh0;
+       } else
+               BUG();
+       list_del_init(&zbpg->bud_list);
+       zbud_unbuddied[found_good_buddy].count--;
+       list_add_tail(&zbpg->bud_list, &zbud_buddied_list);
+       zcache_zbud_buddied_count++;
+
+init_zh:
+       SET_SENTINEL(zh, ZBH);
+       zh->size = size;
+       zh->index = index;
+       zh->oid = *oid;
+       zh->pool_id = pool_id;
+       /* can wait to copy the data until the list locks are dropped */
+       spin_unlock(&zbud_budlists_spinlock);
+
+       to = zbud_data(zh, size);
+       memcpy(to, cdata, size);
+       spin_unlock(&zbpg->lock);
+       zbud_cumul_chunk_counts[nchunks]++;
+       atomic_inc(&zcache_zbud_curr_zpages);
+       zcache_zbud_cumul_zpages++;
+       zcache_zbud_curr_zbytes += size;
+       zcache_zbud_cumul_zbytes += size;
+out:
+       return zh;
+}
+
+static int zbud_decompress(struct page *page, struct zbud_hdr *zh)
+{
+       struct zbud_page *zbpg;
+       unsigned budnum = zbud_budnum(zh);
+       size_t out_len = PAGE_SIZE;
+       char *to_va, *from_va;
+       unsigned size;
+       int ret = 0;
+
+       zbpg = container_of(zh, struct zbud_page, buddy[budnum]);
+       spin_lock(&zbpg->lock);
+       if (list_empty(&zbpg->bud_list)) {
+               /* ignore zombie page... see zbud_evict_pages() */
+               ret = -EINVAL;
+               goto out;
+       }
+       ASSERT_SENTINEL(zh, ZBH);
+       BUG_ON(zh->size == 0 || zh->size > zbud_max_buddy_size());
+       to_va = kmap_atomic(page, KM_USER0);
+       size = zh->size;
+       from_va = zbud_data(zh, size);
+       ret = lzo1x_decompress_safe(from_va, size, to_va, &out_len);
+       BUG_ON(ret != LZO_E_OK);
+       BUG_ON(out_len != PAGE_SIZE);
+       kunmap_atomic(to_va, KM_USER0);
+out:
+       spin_unlock(&zbpg->lock);
+       return ret;
+}
+
+/*
+ * The following routines handle shrinking of ephemeral pages by evicting
+ * pages "least valuable" first.
+ */
+
+static unsigned long zcache_evicted_raw_pages;
+static unsigned long zcache_evicted_buddied_pages;
+static unsigned long zcache_evicted_unbuddied_pages;
+
+static struct tmem_pool *zcache_get_pool_by_id(uint32_t poolid);
+static void zcache_put_pool(struct tmem_pool *pool);
+
+/*
+ * Flush and free all zbuds in a zbpg, then free the pageframe
+ */
+static void zbud_evict_zbpg(struct zbud_page *zbpg)
+{
+       struct zbud_hdr *zh;
+       int i, j;
+       uint32_t pool_id[ZBUD_MAX_BUDS], index[ZBUD_MAX_BUDS];
+       struct tmem_oid oid[ZBUD_MAX_BUDS];
+       struct tmem_pool *pool;
+
+       ASSERT_SPINLOCK(&zbpg->lock);
+       BUG_ON(!list_empty(&zbpg->bud_list));
+       for (i = 0, j = 0; i < ZBUD_MAX_BUDS; i++) {
+               zh = &zbpg->buddy[i];
+               if (zh->size) {
+                       pool_id[j] = zh->pool_id;
+                       oid[j] = zh->oid;
+                       index[j] = zh->index;
+                       j++;
+                       zbud_free(zh);
+               }
+       }
+       spin_unlock(&zbpg->lock);
+       for (i = 0; i < j; i++) {
+               pool = zcache_get_pool_by_id(pool_id[i]);
+               if (pool != NULL) {
+                       tmem_flush_page(pool, &oid[i], index[i]);
+                       zcache_put_pool(pool);
+               }
+       }
+       ASSERT_SENTINEL(zbpg, ZBPG);
+       spin_lock(&zbpg->lock);
+       zbud_free_raw_page(zbpg);
+}
+
+/*
+ * Free nr pages.  This code is funky because we want to hold the locks
+ * protecting various lists for as short a time as possible, and in some
+ * circumstances the list may change asynchronously when the list lock is
+ * not held.  In some cases we also trylock not only to avoid waiting on a
+ * page in use by another cpu, but also to avoid potential deadlock due to
+ * lock inversion.
+ */
+static void zbud_evict_pages(int nr)
+{
+       struct zbud_page *zbpg;
+       int i;
+
+       /* first try freeing any pages on unused list */
+retry_unused_list:
+       spin_lock_bh(&zbpg_unused_list_spinlock);
+       if (!list_empty(&zbpg_unused_list)) {
+               /* can't walk list here, since it may change when unlocked */
+               zbpg = list_first_entry(&zbpg_unused_list,
+                               struct zbud_page, bud_list);
+               list_del_init(&zbpg->bud_list);
+               zcache_zbpg_unused_list_count--;
+               atomic_dec(&zcache_zbud_curr_raw_pages);
+               spin_unlock_bh(&zbpg_unused_list_spinlock);
+               zcache_free_page(zbpg);
+               zcache_evicted_raw_pages++;
+               if (--nr <= 0)
+                       goto out;
+               goto retry_unused_list;
+       }
+       spin_unlock_bh(&zbpg_unused_list_spinlock);
+
+       /* now try freeing unbuddied pages, starting with least space avail */
+       for (i = 0; i < MAX_CHUNK; i++) {
+retry_unbud_list_i:
+               spin_lock_bh(&zbud_budlists_spinlock);
+               if (list_empty(&zbud_unbuddied[i].list)) {
+                       spin_unlock_bh(&zbud_budlists_spinlock);
+                       continue;
+               }
+               list_for_each_entry(zbpg, &zbud_unbuddied[i].list, bud_list) {
+                       if (unlikely(!spin_trylock(&zbpg->lock)))
+                               continue;
+                       list_del_init(&zbpg->bud_list);
+                       zbud_unbuddied[i].count--;
+                       spin_unlock(&zbud_budlists_spinlock);
+                       zcache_evicted_unbuddied_pages++;
+                       /* want budlists unlocked when doing zbpg eviction */
+                       zbud_evict_zbpg(zbpg);
+                       local_bh_enable();
+                       if (--nr <= 0)
+                               goto out;
+                       goto retry_unbud_list_i;
+               }
+               spin_unlock_bh(&zbud_budlists_spinlock);
+       }
+
+       /* as a last resort, free buddied pages */
+retry_bud_list:
+       spin_lock_bh(&zbud_budlists_spinlock);
+       if (list_empty(&zbud_buddied_list)) {
+               spin_unlock_bh(&zbud_budlists_spinlock);
+               goto out;
+       }
+       list_for_each_entry(zbpg, &zbud_buddied_list, bud_list) {
+               if (unlikely(!spin_trylock(&zbpg->lock)))
+                       continue;
+               list_del_init(&zbpg->bud_list);
+               zcache_zbud_buddied_count--;
+               spin_unlock(&zbud_budlists_spinlock);
+               zcache_evicted_buddied_pages++;
+               /* want budlists unlocked when doing zbpg eviction */
+               zbud_evict_zbpg(zbpg);
+               local_bh_enable();
+               if (--nr <= 0)
+                       goto out;
+               goto retry_bud_list;
+       }
+       spin_unlock_bh(&zbud_budlists_spinlock);
+out:
+       return;
+}
+
+static void zbud_init(void)
+{
+       int i;
+
+       INIT_LIST_HEAD(&zbud_buddied_list);
+       zcache_zbud_buddied_count = 0;
+       for (i = 0; i < NCHUNKS; i++) {
+               INIT_LIST_HEAD(&zbud_unbuddied[i].list);
+               zbud_unbuddied[i].count = 0;
+       }
+}
+
+#ifdef CONFIG_SYSFS
+/*
+ * These sysfs routines show a nice distribution of how many zbpg's are
+ * currently (and have ever been placed) in each unbuddied list.  It's fun
+ * to watch but can probably go away before final merge.
+ */
+static int zbud_show_unbuddied_list_counts(char *buf)
+{
+       int i;
+       char *p = buf;
+
+       for (i = 0; i < NCHUNKS - 1; i++)
+               p += sprintf(p, "%u ", zbud_unbuddied[i].count);
+       p += sprintf(p, "%d\n", zbud_unbuddied[i].count);
+       return p - buf;
+}
+
+static int zbud_show_cumul_chunk_counts(char *buf)
+{
+       unsigned long i, chunks = 0, total_chunks = 0, sum_total_chunks = 0;
+       unsigned long total_chunks_lte_21 = 0, total_chunks_lte_32 = 0;
+       unsigned long total_chunks_lte_42 = 0;
+       char *p = buf;
+
+       for (i = 0; i < NCHUNKS; i++) {
+               p += sprintf(p, "%lu ", zbud_cumul_chunk_counts[i]);
+               chunks += zbud_cumul_chunk_counts[i];
+               total_chunks += zbud_cumul_chunk_counts[i];
+               sum_total_chunks += i * zbud_cumul_chunk_counts[i];
+               if (i == 21)
+                       total_chunks_lte_21 = total_chunks;
+               if (i == 32)
+                       total_chunks_lte_32 = total_chunks;
+               if (i == 42)
+                       total_chunks_lte_42 = total_chunks;
+       }
+       p += sprintf(p, "<=21:%lu <=32:%lu <=42:%lu, mean:%lu\n",
+               total_chunks_lte_21, total_chunks_lte_32, total_chunks_lte_42,
+               chunks == 0 ? 0 : sum_total_chunks / chunks);
+       return p - buf;
+}
+#endif
+
+/**********
+ * This "zv" PAM implementation combines the TLSF-based xvMalloc
+ * with lzo1x compression to maximize the amount of data that can
+ * be packed into a physical page.
+ *
+ * Zv represents a PAM page with the index and object (plus a "size" value
+ * necessary for decompression) immediately preceding the compressed data.
+ */
+
+#define ZVH_SENTINEL  0x43214321
+
+struct zv_hdr {
+       uint32_t pool_id;
+       struct tmem_oid oid;
+       uint32_t index;
+       DECL_SENTINEL
+};
+
+static const int zv_max_page_size = (PAGE_SIZE / 8) * 7;
+
+static struct zv_hdr *zv_create(struct xv_pool *xvpool, uint32_t pool_id,
+                               struct tmem_oid *oid, uint32_t index,
+                               void *cdata, unsigned clen)
+{
+       struct page *page;
+       struct zv_hdr *zv = NULL;
+       uint32_t offset;
+       int ret;
+
+       BUG_ON(!irqs_disabled());
+       ret = xv_malloc(xvpool, clen + sizeof(struct zv_hdr),
+                       &page, &offset, ZCACHE_GFP_MASK);
+       if (unlikely(ret))
+               goto out;
+       zv = kmap_atomic(page, KM_USER0) + offset;
+       zv->index = index;
+       zv->oid = *oid;
+       zv->pool_id = pool_id;
+       SET_SENTINEL(zv, ZVH);
+       memcpy((char *)zv + sizeof(struct zv_hdr), cdata, clen);
+       kunmap_atomic(zv, KM_USER0);
+out:
+       return zv;
+}
+
+static void zv_free(struct xv_pool *xvpool, struct zv_hdr *zv)
+{
+       unsigned long flags;
+       struct page *page;
+       uint32_t offset;
+       uint16_t size;
+
+       ASSERT_SENTINEL(zv, ZVH);
+       size = xv_get_object_size(zv) - sizeof(*zv);
+       BUG_ON(size == 0 || size > zv_max_page_size);
+       INVERT_SENTINEL(zv, ZVH);
+       page = virt_to_page(zv);
+       offset = (unsigned long)zv & ~PAGE_MASK;
+       local_irq_save(flags);
+       xv_free(xvpool, page, offset);
+       local_irq_restore(flags);
+}
+
+static void zv_decompress(struct page *page, struct zv_hdr *zv)
+{
+       size_t clen = PAGE_SIZE;
+       char *to_va;
+       unsigned size;
+       int ret;
+
+       ASSERT_SENTINEL(zv, ZVH);
+       size = xv_get_object_size(zv) - sizeof(*zv);
+       BUG_ON(size == 0 || size > zv_max_page_size);
+       to_va = kmap_atomic(page, KM_USER0);
+       ret = lzo1x_decompress_safe((char *)zv + sizeof(*zv),
+                                       size, to_va, &clen);
+       kunmap_atomic(to_va, KM_USER0);
+       BUG_ON(ret != LZO_E_OK);
+       BUG_ON(clen != PAGE_SIZE);
+}
+
+/*
+ * zcache core code starts here
+ */
+
+/* useful stats not collected by cleancache or frontswap */
+static unsigned long zcache_flush_total;
+static unsigned long zcache_flush_found;
+static unsigned long zcache_flobj_total;
+static unsigned long zcache_flobj_found;
+static unsigned long zcache_failed_eph_puts;
+static unsigned long zcache_failed_pers_puts;
+
+#define MAX_POOLS_PER_CLIENT 16
+
+static struct {
+       struct tmem_pool *tmem_pools[MAX_POOLS_PER_CLIENT];
+       struct xv_pool *xvpool;
+} zcache_client;
+
+/*
+ * Tmem operations assume the poolid implies the invoking client.
+ * Zcache only has one client (the kernel itself), so translate
+ * the poolid into the tmem_pool allocated for it.  A KVM version
+ * of zcache would have one client per guest and each client might
+ * have a poolid==N.
+ */
+static struct tmem_pool *zcache_get_pool_by_id(uint32_t poolid)
+{
+       struct tmem_pool *pool = NULL;
+
+       if (poolid >= 0) {
+               pool = zcache_client.tmem_pools[poolid];
+               if (pool != NULL)
+                       atomic_inc(&pool->refcount);
+       }
+       return pool;
+}
+
+static void zcache_put_pool(struct tmem_pool *pool)
+{
+       if (pool != NULL)
+               atomic_dec(&pool->refcount);
+}
+
+/* counters for debugging */
+static unsigned long zcache_failed_get_free_pages;
+static unsigned long zcache_failed_alloc;
+static unsigned long zcache_put_to_flush;
+static unsigned long zcache_aborted_preload;
+static unsigned long zcache_aborted_shrink;
+
+/*
+ * Ensure that memory allocation requests in zcache don't result
+ * in direct reclaim requests via the shrinker, which would cause
+ * an infinite loop.  Maybe a GFP flag would be better?
+ */
+static DEFINE_SPINLOCK(zcache_direct_reclaim_lock);
+
+/*
+ * for now, used named slabs so can easily track usage; later can
+ * either just use kmalloc, or perhaps add a slab-like allocator
+ * to more carefully manage total memory utilization
+ */
+static struct kmem_cache *zcache_objnode_cache;
+static struct kmem_cache *zcache_obj_cache;
+static atomic_t zcache_curr_obj_count = ATOMIC_INIT(0);
+static unsigned long zcache_curr_obj_count_max;
+static atomic_t zcache_curr_objnode_count = ATOMIC_INIT(0);
+static unsigned long zcache_curr_objnode_count_max;
+
+/*
+ * to avoid memory allocation recursion (e.g. due to direct reclaim), we
+ * preload all necessary data structures so the hostops callbacks never
+ * actually do a malloc
+ */
+struct zcache_preload {
+       void *page;
+       struct tmem_obj *obj;
+       int nr;
+       struct tmem_objnode *objnodes[OBJNODE_TREE_MAX_PATH];
+};
+static DEFINE_PER_CPU(struct zcache_preload, zcache_preloads) = { 0, };
+
+static int zcache_do_preload(struct tmem_pool *pool)
+{
+       struct zcache_preload *kp;
+       struct tmem_objnode *objnode;
+       struct tmem_obj *obj;
+       void *page;
+       int ret = -ENOMEM;
+
+       if (unlikely(zcache_objnode_cache == NULL))
+               goto out;
+       if (unlikely(zcache_obj_cache == NULL))
+               goto out;
+       if (!spin_trylock(&zcache_direct_reclaim_lock)) {
+               zcache_aborted_preload++;
+               goto out;
+       }
+       preempt_disable();
+       kp = &__get_cpu_var(zcache_preloads);
+       while (kp->nr < ARRAY_SIZE(kp->objnodes)) {
+               preempt_enable_no_resched();
+               objnode = kmem_cache_alloc(zcache_objnode_cache,
+                               ZCACHE_GFP_MASK);
+               if (unlikely(objnode == NULL)) {
+                       zcache_failed_alloc++;
+                       goto unlock_out;
+               }
+               preempt_disable();
+               kp = &__get_cpu_var(zcache_preloads);
+               if (kp->nr < ARRAY_SIZE(kp->objnodes))
+                       kp->objnodes[kp->nr++] = objnode;
+               else
+                       kmem_cache_free(zcache_objnode_cache, objnode);
+       }
+       preempt_enable_no_resched();
+       obj = kmem_cache_alloc(zcache_obj_cache, ZCACHE_GFP_MASK);
+       if (unlikely(obj == NULL)) {
+               zcache_failed_alloc++;
+               goto unlock_out;
+       }
+       page = (void *)__get_free_page(ZCACHE_GFP_MASK);
+       if (unlikely(page == NULL)) {
+               zcache_failed_get_free_pages++;
+               kmem_cache_free(zcache_obj_cache, obj);
+               goto unlock_out;
+       }
+       preempt_disable();
+       kp = &__get_cpu_var(zcache_preloads);
+       if (kp->obj == NULL)
+               kp->obj = obj;
+       else
+               kmem_cache_free(zcache_obj_cache, obj);
+       if (kp->page == NULL)
+               kp->page = page;
+       else
+               free_page((unsigned long)page);
+       ret = 0;
+unlock_out:
+       spin_unlock(&zcache_direct_reclaim_lock);
+out:
+       return ret;
+}
+
+static void *zcache_get_free_page(void)
+{
+       struct zcache_preload *kp;
+       void *page;
+
+       kp = &__get_cpu_var(zcache_preloads);
+       page = kp->page;
+       BUG_ON(page == NULL);
+       kp->page = NULL;
+       return page;
+}
+
+static void zcache_free_page(void *p)
+{
+       free_page((unsigned long)p);
+}
+
+/*
+ * zcache implementation for tmem host ops
+ */
+
+static struct tmem_objnode *zcache_objnode_alloc(struct tmem_pool *pool)
+{
+       struct tmem_objnode *objnode = NULL;
+       unsigned long count;
+       struct zcache_preload *kp;
+
+       kp = &__get_cpu_var(zcache_preloads);
+       if (kp->nr <= 0)
+               goto out;
+       objnode = kp->objnodes[kp->nr - 1];
+       BUG_ON(objnode == NULL);
+       kp->objnodes[kp->nr - 1] = NULL;
+       kp->nr--;
+       count = atomic_inc_return(&zcache_curr_objnode_count);
+       if (count > zcache_curr_objnode_count_max)
+               zcache_curr_objnode_count_max = count;
+out:
+       return objnode;
+}
+
+static void zcache_objnode_free(struct tmem_objnode *objnode,
+                                       struct tmem_pool *pool)
+{
+       atomic_dec(&zcache_curr_objnode_count);
+       BUG_ON(atomic_read(&zcache_curr_objnode_count) < 0);
+       kmem_cache_free(zcache_objnode_cache, objnode);
+}
+
+static struct tmem_obj *zcache_obj_alloc(struct tmem_pool *pool)
+{
+       struct tmem_obj *obj = NULL;
+       unsigned long count;
+       struct zcache_preload *kp;
+
+       kp = &__get_cpu_var(zcache_preloads);
+       obj = kp->obj;
+       BUG_ON(obj == NULL);
+       kp->obj = NULL;
+       count = atomic_inc_return(&zcache_curr_obj_count);
+       if (count > zcache_curr_obj_count_max)
+               zcache_curr_obj_count_max = count;
+       return obj;
+}
+
+static void zcache_obj_free(struct tmem_obj *obj, struct tmem_pool *pool)
+{
+       atomic_dec(&zcache_curr_obj_count);
+       BUG_ON(atomic_read(&zcache_curr_obj_count) < 0);
+       kmem_cache_free(zcache_obj_cache, obj);
+}
+
+static struct tmem_hostops zcache_hostops = {
+       .obj_alloc = zcache_obj_alloc,
+       .obj_free = zcache_obj_free,
+       .objnode_alloc = zcache_objnode_alloc,
+       .objnode_free = zcache_objnode_free,
+};
+
+/*
+ * zcache implementations for PAM page descriptor ops
+ */
+
+static atomic_t zcache_curr_eph_pampd_count = ATOMIC_INIT(0);
+static unsigned long zcache_curr_eph_pampd_count_max;
+static atomic_t zcache_curr_pers_pampd_count = ATOMIC_INIT(0);
+static unsigned long zcache_curr_pers_pampd_count_max;
+
+/* forward reference */
+static int zcache_compress(struct page *from, void **out_va, size_t *out_len);
+
+static void *zcache_pampd_create(struct tmem_pool *pool, struct tmem_oid *oid,
+                                uint32_t index, struct page *page)
+{
+       void *pampd = NULL, *cdata;
+       size_t clen;
+       int ret;
+       bool ephemeral = is_ephemeral(pool);
+       unsigned long count;
+
+       if (ephemeral) {
+               ret = zcache_compress(page, &cdata, &clen);
+               if (ret == 0)
+
+                       goto out;
+               if (clen == 0 || clen > zbud_max_buddy_size()) {
+                       zcache_compress_poor++;
+                       goto out;
+               }
+               pampd = (void *)zbud_create(pool->pool_id, oid, index,
+                                               page, cdata, clen);
+               if (pampd != NULL) {
+                       count = atomic_inc_return(&zcache_curr_eph_pampd_count);
+                       if (count > zcache_curr_eph_pampd_count_max)
+                               zcache_curr_eph_pampd_count_max = count;
+               }
+       } else {
+               /*
+                * FIXME: This is all the "policy" there is for now.
+                * 3/4 totpages should allow ~37% of RAM to be filled with
+                * compressed frontswap pages
+                */
+               if (atomic_read(&zcache_curr_pers_pampd_count) >
+                                                       3 * totalram_pages / 4)
+                       goto out;
+               ret = zcache_compress(page, &cdata, &clen);
+               if (ret == 0)
+                       goto out;
+               if (clen > zv_max_page_size) {
+                       zcache_compress_poor++;
+                       goto out;
+               }
+               pampd = (void *)zv_create(zcache_client.xvpool, pool->pool_id,
+                                               oid, index, cdata, clen);
+               if (pampd == NULL)
+                       goto out;
+               count = atomic_inc_return(&zcache_curr_pers_pampd_count);
+               if (count > zcache_curr_pers_pampd_count_max)
+                       zcache_curr_pers_pampd_count_max = count;
+       }
+out:
+       return pampd;
+}
+
+/*
+ * fill the pageframe corresponding to the struct page with the data
+ * from the passed pampd
+ */
+static int zcache_pampd_get_data(struct page *page, void *pampd,
+                                               struct tmem_pool *pool)
+{
+       int ret = 0;
+
+       if (is_ephemeral(pool))
+               ret = zbud_decompress(page, pampd);
+       else
+               zv_decompress(page, pampd);
+       return ret;
+}
+
+/*
+ * free the pampd and remove it from any zcache lists
+ * pampd must no longer be pointed to from any tmem data structures!
+ */
+static void zcache_pampd_free(void *pampd, struct tmem_pool *pool)
+{
+       if (is_ephemeral(pool)) {
+               zbud_free_and_delist((struct zbud_hdr *)pampd);
+               atomic_dec(&zcache_curr_eph_pampd_count);
+               BUG_ON(atomic_read(&zcache_curr_eph_pampd_count) < 0);
+       } else {
+               zv_free(zcache_client.xvpool, (struct zv_hdr *)pampd);
+               atomic_dec(&zcache_curr_pers_pampd_count);
+               BUG_ON(atomic_read(&zcache_curr_pers_pampd_count) < 0);
+       }
+}
+
+static struct tmem_pamops zcache_pamops = {
+       .create = zcache_pampd_create,
+       .get_data = zcache_pampd_get_data,
+       .free = zcache_pampd_free,
+};
+
+/*
+ * zcache compression/decompression and related per-cpu stuff
+ */
+
+#define LZO_WORKMEM_BYTES LZO1X_1_MEM_COMPRESS
+#define LZO_DSTMEM_PAGE_ORDER 1
+static DEFINE_PER_CPU(unsigned char *, zcache_workmem);
+static DEFINE_PER_CPU(unsigned char *, zcache_dstmem);
+
+static int zcache_compress(struct page *from, void **out_va, size_t *out_len)
+{
+       int ret = 0;
+       unsigned char *dmem = __get_cpu_var(zcache_dstmem);
+       unsigned char *wmem = __get_cpu_var(zcache_workmem);
+       char *from_va;
+
+       BUG_ON(!irqs_disabled());
+       if (unlikely(dmem == NULL || wmem == NULL))
+               goto out;  /* no buffer, so can't compress */
+       from_va = kmap_atomic(from, KM_USER0);
+       mb();
+       ret = lzo1x_1_compress(from_va, PAGE_SIZE, dmem, out_len, wmem);
+       BUG_ON(ret != LZO_E_OK);
+       *out_va = dmem;
+       kunmap_atomic(from_va, KM_USER0);
+       ret = 1;
+out:
+       return ret;
+}
+
+
+static int zcache_cpu_notifier(struct notifier_block *nb,
+                               unsigned long action, void *pcpu)
+{
+       int cpu = (long)pcpu;
+       struct zcache_preload *kp;
+
+       switch (action) {
+       case CPU_UP_PREPARE:
+               per_cpu(zcache_dstmem, cpu) = (void *)__get_free_pages(
+                       GFP_KERNEL | __GFP_REPEAT,
+                       LZO_DSTMEM_PAGE_ORDER),
+               per_cpu(zcache_workmem, cpu) =
+                       kzalloc(LZO1X_MEM_COMPRESS,
+                               GFP_KERNEL | __GFP_REPEAT);
+               break;
+       case CPU_DEAD:
+       case CPU_UP_CANCELED:
+               free_pages((unsigned long)per_cpu(zcache_dstmem, cpu),
+                               LZO_DSTMEM_PAGE_ORDER);
+               per_cpu(zcache_dstmem, cpu) = NULL;
+               kfree(per_cpu(zcache_workmem, cpu));
+               per_cpu(zcache_workmem, cpu) = NULL;
+               kp = &per_cpu(zcache_preloads, cpu);
+               while (kp->nr) {
+                       kmem_cache_free(zcache_objnode_cache,
+                                       kp->objnodes[kp->nr - 1]);
+                       kp->objnodes[kp->nr - 1] = NULL;
+                       kp->nr--;
+               }
+               kmem_cache_free(zcache_obj_cache, kp->obj);
+               free_page((unsigned long)kp->page);
+               break;
+       default:
+               break;
+       }
+       return NOTIFY_OK;
+}
+
+static struct notifier_block zcache_cpu_notifier_block = {
+       .notifier_call = zcache_cpu_notifier
+};
+
+#ifdef CONFIG_SYSFS
+#define ZCACHE_SYSFS_RO(_name) \
+       static ssize_t zcache_##_name##_show(struct kobject *kobj, \
+                               struct kobj_attribute *attr, char *buf) \
+       { \
+               return sprintf(buf, "%lu\n", zcache_##_name); \
+       } \
+       static struct kobj_attribute zcache_##_name##_attr = { \
+               .attr = { .name = __stringify(_name), .mode = 0444 }, \
+               .show = zcache_##_name##_show, \
+       }
+
+#define ZCACHE_SYSFS_RO_ATOMIC(_name) \
+       static ssize_t zcache_##_name##_show(struct kobject *kobj, \
+                               struct kobj_attribute *attr, char *buf) \
+       { \
+           return sprintf(buf, "%d\n", atomic_read(&zcache_##_name)); \
+       } \
+       static struct kobj_attribute zcache_##_name##_attr = { \
+               .attr = { .name = __stringify(_name), .mode = 0444 }, \
+               .show = zcache_##_name##_show, \
+       }
+
+#define ZCACHE_SYSFS_RO_CUSTOM(_name, _func) \
+       static ssize_t zcache_##_name##_show(struct kobject *kobj, \
+                               struct kobj_attribute *attr, char *buf) \
+       { \
+           return _func(buf); \
+       } \
+       static struct kobj_attribute zcache_##_name##_attr = { \
+               .attr = { .name = __stringify(_name), .mode = 0444 }, \
+               .show = zcache_##_name##_show, \
+       }
+
+ZCACHE_SYSFS_RO(curr_obj_count_max);
+ZCACHE_SYSFS_RO(curr_objnode_count_max);
+ZCACHE_SYSFS_RO(flush_total);
+ZCACHE_SYSFS_RO(flush_found);
+ZCACHE_SYSFS_RO(flobj_total);
+ZCACHE_SYSFS_RO(flobj_found);
+ZCACHE_SYSFS_RO(failed_eph_puts);
+ZCACHE_SYSFS_RO(failed_pers_puts);
+ZCACHE_SYSFS_RO(zbud_curr_zbytes);
+ZCACHE_SYSFS_RO(zbud_cumul_zpages);
+ZCACHE_SYSFS_RO(zbud_cumul_zbytes);
+ZCACHE_SYSFS_RO(zbud_buddied_count);
+ZCACHE_SYSFS_RO(zbpg_unused_list_count);
+ZCACHE_SYSFS_RO(evicted_raw_pages);
+ZCACHE_SYSFS_RO(evicted_unbuddied_pages);
+ZCACHE_SYSFS_RO(evicted_buddied_pages);
+ZCACHE_SYSFS_RO(failed_get_free_pages);
+ZCACHE_SYSFS_RO(failed_alloc);
+ZCACHE_SYSFS_RO(put_to_flush);
+ZCACHE_SYSFS_RO(aborted_preload);
+ZCACHE_SYSFS_RO(aborted_shrink);
+ZCACHE_SYSFS_RO(compress_poor);
+ZCACHE_SYSFS_RO_ATOMIC(zbud_curr_raw_pages);
+ZCACHE_SYSFS_RO_ATOMIC(zbud_curr_zpages);
+ZCACHE_SYSFS_RO_ATOMIC(curr_obj_count);
+ZCACHE_SYSFS_RO_ATOMIC(curr_objnode_count);
+ZCACHE_SYSFS_RO_CUSTOM(zbud_unbuddied_list_counts,
+                       zbud_show_unbuddied_list_counts);
+ZCACHE_SYSFS_RO_CUSTOM(zbud_cumul_chunk_counts,
+                       zbud_show_cumul_chunk_counts);
+
+static struct attribute *zcache_attrs[] = {
+       &zcache_curr_obj_count_attr.attr,
+       &zcache_curr_obj_count_max_attr.attr,
+       &zcache_curr_objnode_count_attr.attr,
+       &zcache_curr_objnode_count_max_attr.attr,
+       &zcache_flush_total_attr.attr,
+       &zcache_flobj_total_attr.attr,
+       &zcache_flush_found_attr.attr,
+       &zcache_flobj_found_attr.attr,
+       &zcache_failed_eph_puts_attr.attr,
+       &zcache_failed_pers_puts_attr.attr,
+       &zcache_compress_poor_attr.attr,
+       &zcache_zbud_curr_raw_pages_attr.attr,
+       &zcache_zbud_curr_zpages_attr.attr,
+       &zcache_zbud_curr_zbytes_attr.attr,
+       &zcache_zbud_cumul_zpages_attr.attr,
+       &zcache_zbud_cumul_zbytes_attr.attr,
+       &zcache_zbud_buddied_count_attr.attr,
+       &zcache_zbpg_unused_list_count_attr.attr,
+       &zcache_evicted_raw_pages_attr.attr,
+       &zcache_evicted_unbuddied_pages_attr.attr,
+       &zcache_evicted_buddied_pages_attr.attr,
+       &zcache_failed_get_free_pages_attr.attr,
+       &zcache_failed_alloc_attr.attr,
+       &zcache_put_to_flush_attr.attr,
+       &zcache_aborted_preload_attr.attr,
+       &zcache_aborted_shrink_attr.attr,
+       &zcache_zbud_unbuddied_list_counts_attr.attr,
+       &zcache_zbud_cumul_chunk_counts_attr.attr,
+       NULL,
+};
+
+static struct attribute_group zcache_attr_group = {
+       .attrs = zcache_attrs,
+       .name = "zcache",
+};
+
+#endif /* CONFIG_SYSFS */
+/*
+ * When zcache is disabled ("frozen"), pools can be created and destroyed,
+ * but all puts (and thus all other operations that require memory allocation)
+ * must fail.  If zcache is unfrozen, accepts puts, then frozen again,
+ * data consistency requires all puts while frozen to be converted into
+ * flushes.
+ */
+static bool zcache_freeze;
+
+/*
+ * zcache shrinker interface (only useful for ephemeral pages, so zbud only)
+ */
+static int shrink_zcache_memory(struct shrinker *shrink,
+                               struct shrink_control *sc)
+{
+       int ret = -1;
+       int nr = sc->nr_to_scan;
+       gfp_t gfp_mask = sc->gfp_mask;
+
+       if (nr >= 0) {
+               if (!(gfp_mask & __GFP_FS))
+                       /* does this case really need to be skipped? */
+                       goto out;
+               if (spin_trylock(&zcache_direct_reclaim_lock)) {
+                       zbud_evict_pages(nr);
+                       spin_unlock(&zcache_direct_reclaim_lock);
+               } else
+                       zcache_aborted_shrink++;
+       }
+       ret = (int)atomic_read(&zcache_zbud_curr_raw_pages);
+out:
+       return ret;
+}
+
+static struct shrinker zcache_shrinker = {
+       .shrink = shrink_zcache_memory,
+       .seeks = DEFAULT_SEEKS,
+};
+
+/*
+ * zcache shims between cleancache/frontswap ops and tmem
+ */
+
+static int zcache_put_page(int pool_id, struct tmem_oid *oidp,
+                               uint32_t index, struct page *page)
+{
+       struct tmem_pool *pool;
+       int ret = -1;
+
+       BUG_ON(!irqs_disabled());
+       pool = zcache_get_pool_by_id(pool_id);
+       if (unlikely(pool == NULL))
+               goto out;
+       if (!zcache_freeze && zcache_do_preload(pool) == 0) {
+               /* preload does preempt_disable on success */
+               ret = tmem_put(pool, oidp, index, page);
+               if (ret < 0) {
+                       if (is_ephemeral(pool))
+                               zcache_failed_eph_puts++;
+                       else
+                               zcache_failed_pers_puts++;
+               }
+               zcache_put_pool(pool);
+               preempt_enable_no_resched();
+       } else {
+               zcache_put_to_flush++;
+               if (atomic_read(&pool->obj_count) > 0)
+                       /* the put fails whether the flush succeeds or not */
+                       (void)tmem_flush_page(pool, oidp, index);
+               zcache_put_pool(pool);
+       }
+out:
+       return ret;
+}
+
+static int zcache_get_page(int pool_id, struct tmem_oid *oidp,
+                               uint32_t index, struct page *page)
+{
+       struct tmem_pool *pool;
+       int ret = -1;
+       unsigned long flags;
+
+       local_irq_save(flags);
+       pool = zcache_get_pool_by_id(pool_id);
+       if (likely(pool != NULL)) {
+               if (atomic_read(&pool->obj_count) > 0)
+                       ret = tmem_get(pool, oidp, index, page);
+               zcache_put_pool(pool);
+       }
+       local_irq_restore(flags);
+       return ret;
+}
+
+static int zcache_flush_page(int pool_id, struct tmem_oid *oidp, uint32_t index)
+{
+       struct tmem_pool *pool;
+       int ret = -1;
+       unsigned long flags;
+
+       local_irq_save(flags);
+       zcache_flush_total++;
+       pool = zcache_get_pool_by_id(pool_id);
+       if (likely(pool != NULL)) {
+               if (atomic_read(&pool->obj_count) > 0)
+                       ret = tmem_flush_page(pool, oidp, index);
+               zcache_put_pool(pool);
+       }
+       if (ret >= 0)
+               zcache_flush_found++;
+       local_irq_restore(flags);
+       return ret;
+}
+
+static int zcache_flush_object(int pool_id, struct tmem_oid *oidp)
+{
+       struct tmem_pool *pool;
+       int ret = -1;
+       unsigned long flags;
+
+       local_irq_save(flags);
+       zcache_flobj_total++;
+       pool = zcache_get_pool_by_id(pool_id);
+       if (likely(pool != NULL)) {
+               if (atomic_read(&pool->obj_count) > 0)
+                       ret = tmem_flush_object(pool, oidp);
+               zcache_put_pool(pool);
+       }
+       if (ret >= 0)
+               zcache_flobj_found++;
+       local_irq_restore(flags);
+       return ret;
+}
+
+static int zcache_destroy_pool(int pool_id)
+{
+       struct tmem_pool *pool = NULL;
+       int ret = -1;
+
+       if (pool_id < 0)
+               goto out;
+       pool = zcache_client.tmem_pools[pool_id];
+       if (pool == NULL)
+               goto out;
+       zcache_client.tmem_pools[pool_id] = NULL;
+       /* wait for pool activity on other cpus to quiesce */
+       while (atomic_read(&pool->refcount) != 0)
+               ;
+       local_bh_disable();
+       ret = tmem_destroy_pool(pool);
+       local_bh_enable();
+       kfree(pool);
+       pr_info("zcache: destroyed pool id=%d\n", pool_id);
+out:
+       return ret;
+}
+
+static int zcache_new_pool(uint32_t flags)
+{
+       int poolid = -1;
+       struct tmem_pool *pool;
+
+       pool = kmalloc(sizeof(struct tmem_pool), GFP_KERNEL);
+       if (pool == NULL) {
+               pr_info("zcache: pool creation failed: out of memory\n");
+               goto out;
+       }
+
+       for (poolid = 0; poolid < MAX_POOLS_PER_CLIENT; poolid++)
+               if (zcache_client.tmem_pools[poolid] == NULL)
+                       break;
+       if (poolid >= MAX_POOLS_PER_CLIENT) {
+               pr_info("zcache: pool creation failed: max exceeded\n");
+               kfree(pool);
+               poolid = -1;
+               goto out;
+       }
+       atomic_set(&pool->refcount, 0);
+       pool->client = &zcache_client;
+       pool->pool_id = poolid;
+       tmem_new_pool(pool, flags);
+       zcache_client.tmem_pools[poolid] = pool;
+       pr_info("zcache: created %s tmem pool, id=%d\n",
+               flags & TMEM_POOL_PERSIST ? "persistent" : "ephemeral",
+               poolid);
+out:
+       return poolid;
+}
+
+/**********
+ * Two kernel functionalities currently can be layered on top of tmem.
+ * These are "cleancache" which is used as a second-chance cache for clean
+ * page cache pages; and "frontswap" which is used for swap pages
+ * to avoid writes to disk.  A generic "shim" is provided here for each
+ * to translate in-kernel semantics to zcache semantics.
+ */
+
+#ifdef CONFIG_CLEANCACHE
+static void zcache_cleancache_put_page(int pool_id,
+                                       struct cleancache_filekey key,
+                                       pgoff_t index, struct page *page)
+{
+       u32 ind = (u32) index;
+       struct tmem_oid oid = *(struct tmem_oid *)&key;
+
+       if (likely(ind == index))
+               (void)zcache_put_page(pool_id, &oid, index, page);
+}
+
+static int zcache_cleancache_get_page(int pool_id,
+                                       struct cleancache_filekey key,
+                                       pgoff_t index, struct page *page)
+{
+       u32 ind = (u32) index;
+       struct tmem_oid oid = *(struct tmem_oid *)&key;
+       int ret = -1;
+
+       if (likely(ind == index))
+               ret = zcache_get_page(pool_id, &oid, index, page);
+       return ret;
+}
+
+static void zcache_cleancache_flush_page(int pool_id,
+                                       struct cleancache_filekey key,
+                                       pgoff_t index)
+{
+       u32 ind = (u32) index;
+       struct tmem_oid oid = *(struct tmem_oid *)&key;
+
+       if (likely(ind == index))
+               (void)zcache_flush_page(pool_id, &oid, ind);
+}
+
+static void zcache_cleancache_flush_inode(int pool_id,
+                                       struct cleancache_filekey key)
+{
+       struct tmem_oid oid = *(struct tmem_oid *)&key;
+
+       (void)zcache_flush_object(pool_id, &oid);
+}
+
+static void zcache_cleancache_flush_fs(int pool_id)
+{
+       if (pool_id >= 0)
+               (void)zcache_destroy_pool(pool_id);
+}
+
+static int zcache_cleancache_init_fs(size_t pagesize)
+{
+       BUG_ON(sizeof(struct cleancache_filekey) !=
+                               sizeof(struct tmem_oid));
+       BUG_ON(pagesize != PAGE_SIZE);
+       return zcache_new_pool(0);
+}
+
+static int zcache_cleancache_init_shared_fs(char *uuid, size_t pagesize)
+{
+       /* shared pools are unsupported and map to private */
+       BUG_ON(sizeof(struct cleancache_filekey) !=
+                               sizeof(struct tmem_oid));
+       BUG_ON(pagesize != PAGE_SIZE);
+       return zcache_new_pool(0);
+}
+
+static struct cleancache_ops zcache_cleancache_ops = {
+       .put_page = zcache_cleancache_put_page,
+       .get_page = zcache_cleancache_get_page,
+       .flush_page = zcache_cleancache_flush_page,
+       .flush_inode = zcache_cleancache_flush_inode,
+       .flush_fs = zcache_cleancache_flush_fs,
+       .init_shared_fs = zcache_cleancache_init_shared_fs,
+       .init_fs = zcache_cleancache_init_fs
+};
+
+struct cleancache_ops zcache_cleancache_register_ops(void)
+{
+       struct cleancache_ops old_ops =
+               cleancache_register_ops(&zcache_cleancache_ops);
+
+       return old_ops;
+}
+#endif
+
+#ifdef CONFIG_FRONTSWAP
+/* a single tmem poolid is used for all frontswap "types" (swapfiles) */
+static int zcache_frontswap_poolid = -1;
+
+/*
+ * Swizzling increases objects per swaptype, increasing tmem concurrency
+ * for heavy swaploads.  Later, larger nr_cpus -> larger SWIZ_BITS
+ */
+#define SWIZ_BITS              4
+#define SWIZ_MASK              ((1 << SWIZ_BITS) - 1)
+#define _oswiz(_type, _ind)    ((_type << SWIZ_BITS) | (_ind & SWIZ_MASK))
+#define iswiz(_ind)            (_ind >> SWIZ_BITS)
+
+static inline struct tmem_oid oswiz(unsigned type, u32 ind)
+{
+       struct tmem_oid oid = { .oid = { 0 } };
+       oid.oid[0] = _oswiz(type, ind);
+       return oid;
+}
+
+static int zcache_frontswap_put_page(unsigned type, pgoff_t offset,
+                                  struct page *page)
+{
+       u64 ind64 = (u64)offset;
+       u32 ind = (u32)offset;
+       struct tmem_oid oid = oswiz(type, ind);
+       int ret = -1;
+       unsigned long flags;
+
+       BUG_ON(!PageLocked(page));
+       if (likely(ind64 == ind)) {
+               local_irq_save(flags);
+               ret = zcache_put_page(zcache_frontswap_poolid, &oid,
+                                       iswiz(ind), page);
+               local_irq_restore(flags);
+       }
+       return ret;
+}
+
+/* returns 0 if the page was successfully gotten from frontswap, -1 if
+ * was not present (should never happen!) */
+static int zcache_frontswap_get_page(unsigned type, pgoff_t offset,
+                                  struct page *page)
+{
+       u64 ind64 = (u64)offset;
+       u32 ind = (u32)offset;
+       struct tmem_oid oid = oswiz(type, ind);
+       int ret = -1;
+
+       BUG_ON(!PageLocked(page));
+       if (likely(ind64 == ind))
+               ret = zcache_get_page(zcache_frontswap_poolid, &oid,
+                                       iswiz(ind), page);
+       return ret;
+}
+
+/* flush a single page from frontswap */
+static void zcache_frontswap_flush_page(unsigned type, pgoff_t offset)
+{
+       u64 ind64 = (u64)offset;
+       u32 ind = (u32)offset;
+       struct tmem_oid oid = oswiz(type, ind);
+
+       if (likely(ind64 == ind))
+               (void)zcache_flush_page(zcache_frontswap_poolid, &oid,
+                                       iswiz(ind));
+}
+
+/* flush all pages from the passed swaptype */
+static void zcache_frontswap_flush_area(unsigned type)
+{
+       struct tmem_oid oid;
+       int ind;
+
+       for (ind = SWIZ_MASK; ind >= 0; ind--) {
+               oid = oswiz(type, ind);
+               (void)zcache_flush_object(zcache_frontswap_poolid, &oid);
+       }
+}
+
+static void zcache_frontswap_init(unsigned ignored)
+{
+       /* a single tmem poolid is used for all frontswap "types" (swapfiles) */
+       if (zcache_frontswap_poolid < 0)
+               zcache_frontswap_poolid = zcache_new_pool(TMEM_POOL_PERSIST);
+}
+
+static struct frontswap_ops zcache_frontswap_ops = {
+       .put_page = zcache_frontswap_put_page,
+       .get_page = zcache_frontswap_get_page,
+       .flush_page = zcache_frontswap_flush_page,
+       .flush_area = zcache_frontswap_flush_area,
+       .init = zcache_frontswap_init
+};
+
+struct frontswap_ops zcache_frontswap_register_ops(void)
+{
+       struct frontswap_ops old_ops =
+               frontswap_register_ops(&zcache_frontswap_ops);
+
+       return old_ops;
+}
+#endif
+
+/*
+ * zcache initialization
+ * NOTE FOR NOW zcache MUST BE PROVIDED AS A KERNEL BOOT PARAMETER OR
+ * NOTHING HAPPENS!
+ */
+
+static int zcache_enabled;
+
+static int __init enable_zcache(char *s)
+{
+       zcache_enabled = 1;
+       return 1;
+}
+__setup("zcache", enable_zcache);
+
+/* allow independent dynamic disabling of cleancache and frontswap */
+
+static int use_cleancache = 1;
+
+static int __init no_cleancache(char *s)
+{
+       use_cleancache = 0;
+       return 1;
+}
+
+__setup("nocleancache", no_cleancache);
+
+static int use_frontswap = 1;
+
+static int __init no_frontswap(char *s)
+{
+       use_frontswap = 0;
+       return 1;
+}
+
+__setup("nofrontswap", no_frontswap);
+
+static int __init zcache_init(void)
+{
+#ifdef CONFIG_SYSFS
+       int ret = 0;
+
+       ret = sysfs_create_group(mm_kobj, &zcache_attr_group);
+       if (ret) {
+               pr_err("zcache: can't create sysfs\n");
+               goto out;
+       }
+#endif /* CONFIG_SYSFS */
+#if defined(CONFIG_CLEANCACHE) || defined(CONFIG_FRONTSWAP)
+       if (zcache_enabled) {
+               unsigned int cpu;
+
+               tmem_register_hostops(&zcache_hostops);
+               tmem_register_pamops(&zcache_pamops);
+               ret = register_cpu_notifier(&zcache_cpu_notifier_block);
+               if (ret) {
+                       pr_err("zcache: can't register cpu notifier\n");
+                       goto out;
+               }
+               for_each_online_cpu(cpu) {
+                       void *pcpu = (void *)(long)cpu;
+                       zcache_cpu_notifier(&zcache_cpu_notifier_block,
+                               CPU_UP_PREPARE, pcpu);
+               }
+       }
+       zcache_objnode_cache = kmem_cache_create("zcache_objnode",
+                               sizeof(struct tmem_objnode), 0, 0, NULL);
+       zcache_obj_cache = kmem_cache_create("zcache_obj",
+                               sizeof(struct tmem_obj), 0, 0, NULL);
+#endif
+#ifdef CONFIG_CLEANCACHE
+       if (zcache_enabled && use_cleancache) {
+               struct cleancache_ops old_ops;
+
+               zbud_init();
+               register_shrinker(&zcache_shrinker);
+               old_ops = zcache_cleancache_register_ops();
+               pr_info("zcache: cleancache enabled using kernel "
+                       "transcendent memory and compression buddies\n");
+               if (old_ops.init_fs != NULL)
+                       pr_warning("zcache: cleancache_ops overridden");
+       }
+#endif
+#ifdef CONFIG_FRONTSWAP
+       if (zcache_enabled && use_frontswap) {
+               struct frontswap_ops old_ops;
+
+               zcache_client.xvpool = xv_create_pool();
+               if (zcache_client.xvpool == NULL) {
+                       pr_err("zcache: can't create xvpool\n");
+                       goto out;
+               }
+               old_ops = zcache_frontswap_register_ops();
+               pr_info("zcache: frontswap enabled using kernel "
+                       "transcendent memory and xvmalloc\n");
+               if (old_ops.init != NULL)
+                       pr_warning("ktmem: frontswap_ops overridden");
+       }
+#endif
+out:
+       return ret;
+}
+
+module_init(zcache_init)