Re: [PATCH] zcache: rename zcache.c to avoid build problem

[Konrad Rzeszutek Wilk]

On Wed, Jun 22, 2011 at 10:26:29AM +0200, dexen deVries wrote:
> zcache.c was not being compiled as its target filename
> was the same as overall name of module to be built.

Hmm, Dan?

> 
> Signed-off-by: dexen deVries <dexen.devries@xxxxxxxxx>
> ---
>  drivers/staging/zcache/Makefile     |    2 +-
>  drivers/staging/zcache/zcache.c     | 1661 -----------------------------------
>  drivers/staging/zcache/zcache_drv.c | 1661 +++++++++++++++++++++++++++++++++++
>  3 files changed, 1662 insertions(+), 1662 deletions(-)
>  delete mode 100644 drivers/staging/zcache/zcache.c
>  create mode 100644 drivers/staging/zcache/zcache_drv.c
> 
> 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)
> -- 
> 1.7.4.1
> 
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