/*
* z3fold.c
*
* Author: Vitaly Wool <vitaly.wool@konsulko.com>
* Copyright (C) 2016, Sony Mobile Communications Inc.
*
* This implementation is based on zbud written by Seth Jennings.
*
* z3fold is an special purpose allocator for storing compressed pages. It
* can store up to three compressed pages per page which improves the
* compression ratio of zbud while retaining its main concepts (e. g. always
* storing an integral number of objects per page) and simplicity.
* It still has simple and deterministic reclaim properties that make it
* preferable to a higher density approach (with no requirement on integral
* number of object per page) when reclaim is used.
*
* As in zbud, pages are divided into "chunks". The size of the chunks is
* fixed at compile time and is determined by NCHUNKS_ORDER below.
*
* z3fold doesn't export any API and is meant to be used via zpool API.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/atomic.h>
#include <linux/list.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/preempt.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/zpool.h>
/*****************
* Structures
*****************/
struct z3fold_pool;
struct z3fold_ops {
int (*evict)(struct z3fold_pool *pool, unsigned long handle);
};
enum buddy {
HEADLESS = 0,
FIRST,
MIDDLE,
LAST,
BUDDIES_MAX
};
/*
* struct z3fold_header - z3fold page metadata occupying the first chunk of each
* z3fold page, except for HEADLESS pages
* @buddy: links the z3fold page into the relevant list in the pool
* @page_lock: per-page lock
* @refcount: reference cound for the z3fold page
* @first_chunks: the size of the first buddy in chunks, 0 if free
* @middle_chunks: the size of the middle buddy in chunks, 0 if free
* @last_chunks: the size of the last buddy in chunks, 0 if free
* @first_num: the starting number (for the first handle)
*/
struct z3fold_header {
struct list_head buddy;
spinlock_t page_lock;
struct kref refcount;
unsigned short first_chunks;
unsigned short middle_chunks;
unsigned short last_chunks;
unsigned short start_middle;
unsigned short first_num:2;
};
/*
* NCHUNKS_ORDER determines the internal allocation granularity, effectively
* adjusting internal fragmentation. It also determines the number of
* freelists maintained in each pool. NCHUNKS_ORDER of 6 means that the
* allocation granularity will be in chunks of size PAGE_SIZE/64. Some chunks
* in the beginning of an allocated page are occupied by z3fold header, so
* NCHUNKS will be calculated to 63 (or 62 in case CONFIG_DEBUG_SPINLOCK=y),
* which shows the max number of free chunks in z3fold page, also there will
* be 63, or 62, respectively, freelists per pool.
*/
#define NCHUNKS_ORDER 6
#define CHUNK_SHIFT (PAGE_SHIFT - NCHUNKS_ORDER)
#define CHUNK_SIZE (1 << CHUNK_SHIFT)
#define ZHDR_SIZE_ALIGNED round_up(sizeof(struct z3fold_header), CHUNK_SIZE)
#define ZHDR_CHUNKS (ZHDR_SIZE_ALIGNED >> CHUNK_SHIFT)
#define TOTAL_CHUNKS (PAGE_SIZE >> CHUNK_SHIFT)
#define NCHUNKS ((PAGE_SIZE - ZHDR_SIZE_ALIGNED) >> CHUNK_SHIFT)
#define BUDDY_MASK (0x3)
/**
* struct z3fold_pool - stores metadata for each z3fold pool
* @lock: protects all pool fields and first|last_chunk fields of any
* z3fold page in the pool
* @unbuddied: array of lists tracking z3fold pages that contain 2- buddies;
* the lists each z3fold page is added to depends on the size of
* its free region.
* @lru: list tracking the z3fold pages in LRU order by most recently
* added buddy.
* @pages_nr: number of z3fold pages in the pool.
* @ops: pointer to a structure of user defined operations specified at
* pool creation time.
*
* This structure is allocated at pool creation time and maintains metadata
* pertaining to a particular z3fold pool.
*/
struct z3fold_pool {
spinlock_t lock;
struct list_head unbuddied[NCHUNKS];
struct list_head lru;
atomic64_t pages_nr;
const struct z3fold_ops *ops;
struct zpool *zpool;
const struct zpool_ops *zpool_ops;
};
/*
* Internal z3fold page flags
*/
enum z3fold_page_flags {
PAGE_HEADLESS = 0,
MIDDLE_CHUNK_MAPPED,
};
/*****************
* Helpers
*****************/
/* Converts an allocation size in bytes to size in z3fold chunks */
static int size_to_chunks(size_t size)
{
return (size + CHUNK_SIZE - 1) >> CHUNK_SHIFT;
}
#define for_each_unbuddied_list(_iter, _begin) \
for ((_iter) = (_begin); (_iter) < NCHUNKS; (_iter)++)
/* Initializes the z3fold header of a newly allocated z3fold page */
static struct z3fold_header *init_z3fold_page(struct page *page)
{
struct z3fold_header *zhdr = page_address(page);
INIT_LIST_HEAD(&page->lru);
clear_bit(PAGE_HEADLESS, &page->private);
clear_bit(MIDDLE_CHUNK_MAPPED, &page->private);
spin_lock_init(&zhdr->page_lock);
kref_init(&zhdr->refcount);
zhdr->first_chunks = 0;
zhdr->middle_chunks = 0;
zhdr->last_chunks = 0;
zhdr->first_num = 0;
zhdr->start_middle = 0;
INIT_LIST_HEAD(&zhdr->buddy);
return zhdr;
}
/* Resets the struct page fields and frees the page */
static void free_z3fold_page(struct page *page)
{
__free_page(page);
}
static void release_z3fold_page(struct kref *ref)
{
struct z3fold_header *zhdr;
struct page *page;
zhdr = container_of(ref, struct z3fold_header, refcount);
page = virt_to_page(zhdr);
if (!list_empty(&zhdr->buddy))
list_del(&zhdr->buddy);
if (!list_empty(&page->lru))
list_del(&page->lru);
free_z3fold_page(page);
}
/* Lock a z3fold page */
static inline void z3fold_page_lock(struct z3fold_header *zhdr)
{
spin_lock(&zhdr->page_lock);
}
/* Try to lock a z3fold page */
static inline int z3fold_page_trylock(struct z3fold_header *zhdr)
{
return spin_trylock(&zhdr->page_lock);
}
/* Unlock a z3fold page */
static inline void z3fold_page_unlock(struct z3fold_header *zhdr)
{
spin_unlock(&zhdr->page_lock);
}
/*
* Encodes the handle of a particular buddy within a z3fold page
* Pool lock should be held as this function accesses first_num
*/
static unsigned long encode_handle(struct z3fold_header *zhdr, enum buddy bud)
{
unsigned long handle;
handle = (unsigned long)zhdr;
if (bud != HEADLESS)
handle += (bud + zhdr->first_num) & BUDDY_MASK;
return handle;
}
/* Returns the z3fold page where a given handle is stored */
static struct z3fold_header *handle_to_z3fold_header(unsigned long handle)
{
return (struct z3fold_header *)(handle & PAGE_MASK);
}
/*
* (handle & BUDDY_MASK) < zhdr->first_num is possible in encode_handle
* but that doesn't matter. because the masking will result in the
* correct buddy number.
*/
static enum buddy handle_to_buddy(unsigned long handle)
{
struct z3fold_header *zhdr = handle_to_z3fold_header(handle);
return (handle - zhdr->first_num) & BUDDY_MASK;
}
/*
* Returns the number of free chunks in a z3fold page.
* NB: can't be used with HEADLESS pages.
*/
static int num_free_chunks(struct z3fold_header *zhdr)
{
int nfree;
/*
* If there is a middle object, pick up the bigger free space
* either before or after it. Otherwise just subtract the number
* of chunks occupied by the first and the last objects.
*/
if (zhdr->middle_chunks != 0) {
int nfree_before = zhdr->first_chunks ?
0 : zhdr->start_middle - ZHDR_CHUNKS;
int nfree_after = zhdr->last_chunks ?
0 : TOTAL_CHUNKS -
(zhdr->start_middle + zhdr->middle_chunks);
nfree = max(nfree_before, nfree_after);
} else
nfree = NCHUNKS - zhdr->first_chunks - zhdr->last_chunks;
return nfree;
}
/*****************
* API Functions
*****************/
/**
* z3fold_create_pool() - create a new z3fold pool
* @gfp: gfp flags when allocating the z3fold pool structure
* @ops: user-defined operations for the z3fold pool
*
* Return: pointer to the new z3fold pool or NULL if the metadata allocation
* failed.
*/
static struct z3fold_pool *z3fold_create_pool(gfp_t gfp,
const struct z3fold_ops *ops)
{
struct z3fold_pool *pool;
int i;
pool = kzalloc(sizeof(struct z3fold_pool), gfp);
if (!pool)
return NULL;
spin_lock_init(&pool->lock);
for_each_unbuddied_list(i, 0)
INIT_LIST_HEAD(&pool->unbuddied[i]);
INIT_LIST_HEAD(&pool->lru);
atomic64_set(&pool->pages_nr, 0);
pool->ops = ops;
return pool;
}
/**
* z3fold_destroy_pool() - destroys an existing z3fold pool
* @pool: the z3fold pool to be destroyed
*
* The pool should be emptied before this function is called.
*/
static void z3fold_destroy_pool(struct z3fold_pool *pool)
{
kfree(pool);
}
static inline void *mchunk_memmove(struct z3fold_header *zhdr,
unsigned short dst_chunk)
{
void *beg = zhdr;
return memmove(beg + (dst_chunk << CHUNK_SHIFT),
beg + (zhdr->start_middle << CHUNK_SHIFT),
zhdr->middle_chunks << CHUNK_SHIFT);
}
#define BIG_CHUNK_GAP 3
/* Has to be called with lock held */
static int z3fold_compact_page(struct z3fold_header *zhdr)
{
struct page *page = virt_to_page(zhdr);
if (test_bit(MIDDLE_CHUNK_MAPPED, &page->private))
return 0; /* can't move middle chunk, it's used */
if (zhdr->middle_chunks == 0)
return 0; /* nothing to compact */
if (zhdr->first_chunks == 0 && zhdr->last_chunks == 0) {
/* move to the beginning */
mchunk_memmove(zhdr, ZHDR_CHUNKS);
zhdr->first_chunks = zhdr->middle_chunks;
zhdr->middle_chunks = 0;
zhdr->start_middle = 0;
zhdr->first_num++;
return 1;
}
/*
* moving data is expensive, so let's only do that if
* there's substantial gain (at least BIG_CHUNK_GAP chunks)
*/
if (zhdr->first_chunks != 0 && zhdr->last_chunks == 0 &&
zhdr->start_middle - (zhdr->first_chunks + ZHDR_CHUNKS) >=
BIG_CHUNK_GAP) {
mchunk_memmove(zhdr, zhdr->first_chunks + ZHDR_CHUNKS);
zhdr->start_middle = zhdr->first_chunks + ZHDR_CHUNKS;
return 1;
} else if (zhdr->last_chunks != 0 && zhdr->first_chunks == 0 &&
TOTAL_CHUNKS - (zhdr->last_chunks + zhdr->start_middle
+ zhdr->middle_chunks) >=
BIG_CHUNK_GAP) {
unsigned short new_start = TOTAL_CHUNKS - zhdr->last_chunks -
zhdr->middle_chunks;
mchunk_memmove(zhdr, new_start);
zhdr->start_middle = new_start;
return 1;
}
return 0;
}
/**
* z3fold_alloc() - allocates a region of a given size
* @pool: z3fold pool from which to allocate
* @size: size in bytes of the desired allocation
* @gfp: gfp flags used if the pool needs to grow
* @handle: handle of the new allocation
*
* This function will attempt to find a free region in the pool large enough to
* satisfy the allocation request. A search of the unbuddied lists is
* performed first. If no suitable free region is found, then a new page is
* allocated and added to the pool to satisfy the request.
*
* gfp should not set __GFP_HIGHMEM as highmem pages cannot be used
* as z3fold pool pages.
*
* Return: 0 if success and handle is set, otherwise -EINVAL if the size or
* gfp arguments are invalid or -ENOMEM if the pool was unable to allocate
* a new page.
*/
static int z3fold_alloc(struct z3fold_pool *pool, size_t size, gfp_t gfp,
unsigned long *handle)
{
int chunks = 0, i, freechunks;
struct z3fold_header *zhdr = NULL;
enum buddy bud;
struct page *page;
if (!size || (gfp & __GFP_HIGHMEM))
return -EINVAL;
if (size > PAGE_SIZE)
return -ENOSPC;
if (size > PAGE_SIZE - ZHDR_SIZE_ALIGNED - CHUNK_SIZE)
bud = HEADLESS;
else {
chunks = size_to_chunks(size);
/* First, try to find an unbuddied z3fold page. */
zhdr = NULL;
for_each_unbuddied_list(i, chunks) {
spin_lock(&pool->lock);
zhdr = list_first_entry_or_null(&pool->unbuddied[i],
struct z3fold_header, buddy);
if (!zhdr || !z3fold_page_trylock(zhdr)) {
spin_unlock(&pool->lock);
continue;
}
kref_get(&zhdr->refcount);
list_del_init(&zhdr->buddy);
spin_unlock(&pool->lock);
page = virt_to_page(zhdr);
if (zhdr->first_chunks == 0) {
if (zhdr->middle_chunks != 0 &&
chunks >= zhdr->start_middle)
bud = LAST;
else
bud = FIRST;
} else if (zhdr->last_chunks == 0)
bud = LAST;
else if (zhdr->middle_chunks == 0)
bud = MIDDLE;
else {
z3fold_page_unlock(zhdr);
spin_lock(&pool->lock);
if (kref_put(&zhdr->refcount,
release_z3fold_page))
atomic64_dec(&pool->pages_nr);
spin_unlock(&pool->lock);
pr_err("No free chunks in unbuddied\n");
WARN_ON(1);
continue;
}
goto found;
}
bud = FIRST;
}
/* Couldn't find unbuddied z3fold page, create new one */
page = alloc_page(gfp);
if (!page)
return -ENOMEM;
atomic64_inc(&pool->pages_nr);
zhdr = init_z3fold_page(page);
if (bud == HEADLESS) {
set_bit(PAGE_HEADLESS, &page->private);
spin_lock(&pool->lock);
goto headless;
}
z3fold_page_lock(zhdr);
found:
if (bud == FIRST)
zhdr->first_chunks = chunks;
else if (bud == LAST)
zhdr->last_chunks = chunks;
else {
zhdr->middle_chunks = chunks;
zhdr->start_middle = zhdr->first_chunks + ZHDR_CHUNKS;
}
spin_lock(&pool->lock);
if (zhdr->first_chunks == 0 || zhdr->last_chunks == 0 ||
zhdr->middle_chunks == 0) {
/* Add to unbuddied list */
freechunks = num_free_chunks(zhdr);
list_add(&zhdr->buddy, &pool->unbuddied[freechunks]);
}
headless:
/* Add/move z3fold page to beginning of LRU */
if (!list_empty(&page->lru))
list_del(&page->lru);
list_add(&page->lru, &pool->lru);
*handle = encode_handle(zhdr, bud);
spin_unlock(&pool->lock);
if (bud != HEADLESS)
z3fold_page_unlock(zhdr);
return 0;
}
/**
* z3fold_free() - frees the allocation associated with the given handle
* @pool: pool in which the allocation resided
* @handle: handle associated with the allocation returned by z3fold_alloc()
*
* In the case that the z3fold page in which the allocation resides is under
* reclaim, as indicated by the PG_reclaim flag being set, this function
* only sets the first|last_chunks to 0. The page is actually freed
* once both buddies are evicted (see z3fold_reclaim_page() below).
*/
static void z3fold_free(struct z3fold_pool *pool, unsigned long handle)
{
struct z3fold_header *zhdr;
int freechunks;
struct page *page;
enum buddy bud;
zhdr = handle_to_z3fold_header(handle);
page = virt_to_page(zhdr);
if (test_bit(PAGE_HEADLESS, &page->private)) {
/* HEADLESS page stored */
bud = HEADLESS;
} else {
z3fold_page_lock(zhdr);
bud = handle_to_buddy(handle);
switch (bud) {
case FIRST:
zhdr->first_chunks = 0;
break;
case MIDDLE:
zhdr->middle_chunks = 0;
zhdr->start_middle = 0;
break;
case LAST:
zhdr->last_chunks = 0;
break;
default:
pr_err("%s: unknown bud %d\n", __func__, bud);
WARN_ON(1);
z3fold_page_unlock(zhdr);
return;
}
}
if (bud == HEADLESS) {
spin_lock(&pool->lock);
list_del(&page->lru);
spin_unlock(&pool->lock);
free_z3fold_page(page);
atomic64_dec(&pool->pages_nr);
} else {
if (zhdr->first_chunks != 0 || zhdr->middle_chunks != 0 ||
zhdr->last_chunks != 0) {
z3fold_compact_page(zhdr);
/* Add to the unbuddied list */
spin_lock(&pool->lock);
if (!list_empty(&zhdr->buddy))
list_del(&zhdr->buddy);
freechunks = num_free_chunks(zhdr);
list_add(&zhdr->buddy, &pool->unbuddied[freechunks]);
spin_unlock(&pool->lock);
}
z3fold_page_unlock(zhdr);
spin_lock(&pool->lock);
if (kref_put(&zhdr->refcount, release_z3fold_page))
atomic64_dec(&pool->pages_nr);
spin_unlock(&pool->lock);
}
}
/**
* z3fold_reclaim_page() - evicts allocations from a pool page and frees it
* @pool: pool from which a page will attempt to be evicted
* @retires: number of pages on the LRU list for which eviction will
* be attempted before failing
*
* z3fold reclaim is different from normal system reclaim in that it is done
* from the bottom, up. This is because only the bottom layer, z3fold, has
* information on how the allocations are organized within each z3fold page.
* This has the potential to create interesting locking situations between
* z3fold and the user, however.
*
* To avoid these, this is how z3fold_reclaim_page() should be called:
* The user detects a page should be reclaimed and calls z3fold_reclaim_page().
* z3fold_reclaim_page() will remove a z3fold page from the pool LRU list and
* call the user-defined eviction handler with the pool and handle as
* arguments.
*
* If the handle can not be evicted, the eviction handler should return
* non-zero. z3fold_reclaim_page() will add the z3fold page back to the
* appropriate list and try the next z3fold page on the LRU up to
* a user defined number of retries.
*
* If the handle is successfully evicted, the eviction handler should
* return 0 _and_ should have called z3fold_free() on the handle. z3fold_free()
* contains logic to delay freeing the page if the page is under reclaim,
* as indicated by the setting of the PG_reclaim flag on the underlying page.
*
* If all buddies in the z3fold page are successfully evicted, then the
* z3fold page can be freed.
*
* Returns: 0 if page is successfully freed, otherwise -EINVAL if there are
* no pages to evict or an eviction handler is not registered, -EAGAIN if
* the retry limit was hit.
*/
static int z3fold_reclaim_page(struct z3fold_pool *pool, unsigned int retries)
{
int i, ret = 0, freechunks;
struct z3fold_header *zhdr;
struct page *page;
unsigned long first_handle = 0, middle_handle = 0, last_handle = 0;
spin_lock(&pool->lock);
if (!pool->ops || !pool->ops->evict || retries == 0) {
spin_unlock(&pool->lock);
return -EINVAL;
}
for (i = 0; i < retries; i++) {
if (list_empty(&pool->lru)) {
spin_unlock(&pool->lock);
return -EINVAL;
}
page = list_last_entry(&pool->lru, struct page, lru);
list_del_init(&page->lru);
zhdr = page_address(page);
if (!test_bit(PAGE_HEADLESS, &page->private)) {
if (!list_empty(&zhdr->buddy))
list_del_init(&zhdr->buddy);
kref_get(&zhdr->refcount);
spin_unlock(&pool->lock);
z3fold_page_lock(zhdr);
/*
* We need encode the handles before unlocking, since
* we can race with free that will set
* (first|last)_chunks to 0
*/
first_handle = 0;
last_handle = 0;
middle_handle = 0;
if (zhdr->first_chunks)
first_handle = encode_handle(zhdr, FIRST);
if (zhdr->middle_chunks)
middle_handle = encode_handle(zhdr, MIDDLE);
if (zhdr->last_chunks)
last_handle = encode_handle(zhdr, LAST);
z3fold_page_unlock(zhdr);
} else {
first_handle = encode_handle(zhdr, HEADLESS);
last_handle = middle_handle = 0;
spin_unlock(&pool->lock);
}
/* Issue the eviction callback(s) */
if (middle_handle) {
ret = pool->ops->evict(pool, middle_handle);
if (ret)
goto next;
}
if (first_handle) {
ret = pool->ops->evict(pool, first_handle);
if (ret)
goto next;
}
if (last_handle) {
ret = pool->ops->evict(pool, last_handle);
if (ret)
goto next;
}
next:
if (test_bit(PAGE_HEADLESS, &page->private)) {
if (ret == 0) {
free_z3fold_page(page);
return 0;
} else {
spin_lock(&pool->lock);
}
} else {
z3fold_page_lock(zhdr);
if ((zhdr->first_chunks || zhdr->last_chunks ||
zhdr->middle_chunks) &&
!(zhdr->first_chunks && zhdr->last_chunks &&
zhdr->middle_chunks)) {
z3fold_compact_page(zhdr);
/* add to unbuddied list */
spin_lock(&pool->lock);
freechunks = num_free_chunks(zhdr);
list_add(&zhdr->buddy,
&pool->unbuddied[freechunks]);
spin_unlock(&pool->lock);
}
z3fold_page_unlock(zhdr);
spin_lock(&pool->lock);
if (kref_put(&zhdr->refcount, release_z3fold_page)) {
spin_unlock(&pool->lock);
atomic64_dec(&pool->pages_nr);
return 0;
}
}
/*
* Add to the beginning of LRU.
* Pool lock has to be kept here to ensure the page has
* not already been released
*/
list_add(&page->lru, &pool->lru);
}
spin_unlock(&pool->lock);
return -EAGAIN;
}
/**
* z3fold_map() - maps the allocation associated with the given handle
* @pool: pool in which the allocation resides
* @handle: handle associated with the allocation to be mapped
*
* Extracts the buddy number from handle and constructs the pointer to the
* correct starting chunk within the page.
*
* Returns: a pointer to the mapped allocation
*/
static void *z3fold_map(struct z3fold_pool *pool, unsigned long handle)
{
struct z3fold_header *zhdr;
struct page *page;
void *addr;
enum buddy buddy;
zhdr = handle_to_z3fold_header(handle);
addr = zhdr;
page = virt_to_page(zhdr);
if (test_bit(PAGE_HEADLESS, &page->private))
goto out;
z3fold_page_lock(zhdr);
buddy = handle_to_buddy(handle);
switch (buddy) {
case FIRST:
addr += ZHDR_SIZE_ALIGNED;
break;
case MIDDLE:
addr += zhdr->start_middle << CHUNK_SHIFT;
set_bit(MIDDLE_CHUNK_MAPPED, &page->private);
break;
case LAST:
addr += PAGE_SIZE - (zhdr->last_chunks << CHUNK_SHIFT);
break;
default:
pr_err("unknown buddy id %d\n", buddy);
WARN_ON(1);
addr = NULL;
break;
}
z3fold_page_unlock(zhdr);
out:
return addr;
}
/**
* z3fold_unmap() - unmaps the allocation associated with the given handle
* @pool: pool in which the allocation resides
* @handle: handle associated with the allocation to be unmapped
*/
static void z3fold_unmap(struct z3fold_pool *pool, unsigned long handle)
{
struct z3fold_header *zhdr;
struct page *page;
enum buddy buddy;
zhdr = handle_to_z3fold_header(handle);
page = virt_to_page(zhdr);
if (test_bit(PAGE_HEADLESS, &page->private))
return;
z3fold_page_lock(zhdr);
buddy = handle_to_buddy(handle);
if (buddy == MIDDLE)
clear_bit(MIDDLE_CHUNK_MAPPED, &page->private);
z3fold_page_unlock(zhdr);
}
/**
* z3fold_get_pool_size() - gets the z3fold pool size in pages
* @pool: pool whose size is being queried
*
* Returns: size in pages of the given pool.
*/
static u64 z3fold_get_pool_size(struct z3fold_pool *pool)
{
return atomic64_read(&pool->pages_nr);
}
/*****************
* zpool
****************/
static int z3fold_zpool_evict(struct z3fold_pool *pool, unsigned long handle)
{
if (pool->zpool && pool->zpool_ops && pool->zpool_ops->evict)
return pool->zpool_ops->evict(pool->zpool, handle);
else
return -ENOENT;
}
static const struct z3fold_ops z3fold_zpool_ops = {
.evict = z3fold_zpool_evict
};
static void *z3fold_zpool_create(const char *name, gfp_t gfp,
const struct zpool_ops *zpool_ops,
struct zpool *zpool)
{
struct z3fold_pool *pool;
pool = z3fold_create_pool(gfp, zpool_ops ? &z3fold_zpool_ops : NULL);
if (pool) {
pool->zpool = zpool;
pool->zpool_ops = zpool_ops;
}
return pool;
}
static void z3fold_zpool_destroy(void *pool)
{
z3fold_destroy_pool(pool);
}
static int z3fold_zpool_malloc(void *pool, size_t size, gfp_t gfp,
unsigned long *handle)
{
return z3fold_alloc(pool, size, gfp, handle);
}
static void z3fold_zpool_free(void *pool, unsigned long handle)
{
z3fold_free(pool, handle);
}
static int z3fold_zpool_shrink(void *pool, unsigned int pages,
unsigned int *reclaimed)
{
unsigned int total = 0;
int ret = -EINVAL;
while (total < pages) {
ret = z3fold_reclaim_page(pool, 8);
if (ret < 0)
break;
total++;
}
if (reclaimed)
*reclaimed = total;
return ret;
}
static void *z3fold_zpool_map(void *pool, unsigned long handle,
enum zpool_mapmode mm)
{
return z3fold_map(pool, handle);
}
static void z3fold_zpool_unmap(void *pool, unsigned long handle)
{
z3fold_unmap(pool, handle);
}
static u64 z3fold_zpool_total_size(void *pool)
{
return z3fold_get_pool_size(pool) * PAGE_SIZE;
}
static struct zpool_driver z3fold_zpool_driver = {
.type = "z3fold",
.owner = THIS_MODULE,
.create = z3fold_zpool_create,
.destroy = z3fold_zpool_destroy,
.malloc = z3fold_zpool_malloc,
.free = z3fold_zpool_free,
.shrink = z3fold_zpool_shrink,
.map = z3fold_zpool_map,
.unmap = z3fold_zpool_unmap,
.total_size = z3fold_zpool_total_size,
};
MODULE_ALIAS("zpool-z3fold");
static int __init init_z3fold(void)
{
/* Make sure the z3fold header is not larger than the page size */
BUILD_BUG_ON(ZHDR_SIZE_ALIGNED > PAGE_SIZE);
zpool_register_driver(&z3fold_zpool_driver);
return 0;
}
static void __exit exit_z3fold(void)
{
zpool_unregister_driver(&z3fold_zpool_driver);
}
module_init(init_z3fold);
module_exit(exit_z3fold);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Vitaly Wool <vitalywool@gmail.com>");
MODULE_DESCRIPTION("3-Fold Allocator for Compressed Pages");
