diff --git a/Documentation/vm/z3fold.txt b/Documentation/vm/z3fold.txt
new file mode 100644
index 000000000000..38e4dac810b6
--- /dev/null
+++ b/Documentation/vm/z3fold.txt
@@ -0,0 +1,26 @@
+z3fold
+------
+
+z3fold is a special purpose allocator for storing compressed pages.
+It is designed to store up to three compressed pages per physical page.
+It is a zbud derivative which allows for higher compression
+ratio keeping the simplicity and determinism of its predecessor.
+
+The main differences between z3fold and zbud are:
+* unlike zbud, z3fold allows for up to PAGE_SIZE allocations
+* z3fold can hold up to 3 compressed pages in its page
+* z3fold doesn't export any API itself and is thus intended to be used
+ via the zpool API.
+
+To keep the determinism and simplicity, z3fold, just like zbud, always
+stores an integral number of compressed pages per page, but it can store
+up to 3 pages unlike zbud which can store at most 2. Therefore the
+compression ratio goes to around 2.7x while zbud's one is around 1.7x.
+
+Unlike zbud (but like zsmalloc for that matter) z3fold_alloc() does not
+return a dereferenceable pointer. Instead, it returns an unsigned long
+handle which encodes actual location of the allocated object.
+
+Keeping effective compression ratio close to zsmalloc's, z3fold doesn't
+depend on MMU enabled and provides more predictable reclaim behavior
+which makes it a better fit for small and response-critical systems.
diff --git a/mm/Kconfig b/mm/Kconfig
index b0432b71137d..1a6a28ebcb8b 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -567,7 +567,7 @@ config ZPOOL
zsmalloc.
config ZBUD
- tristate "Low density storage for compressed pages"
+ tristate "Low (Up to 2x) density storage for compressed pages"
default n
help
A special purpose allocator for storing compressed pages.
@@ -576,6 +576,16 @@ config ZBUD
deterministic reclaim properties that make it preferable to a higher
density approach when reclaim will be used.
+config Z3FOLD
+ tristate "Up to 3x density storage for compressed pages"
+ depends on ZPOOL
+ default n
+ help
+ A special purpose allocator for storing compressed pages.
+ It is designed to store up to three compressed pages per physical
+ page. It is a ZBUD derivative so the simplicity and determinism are
+ still there.
+
config ZSMALLOC
tristate "Memory allocator for compressed pages"
depends on MMU
diff --git a/mm/Makefile b/mm/Makefile
index deb467edca2d..78c6f7dedb83 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -89,6 +89,7 @@ obj-$(CONFIG_MEMORY_ISOLATION) += page_isolation.o
obj-$(CONFIG_ZPOOL) += zpool.o
obj-$(CONFIG_ZBUD) += zbud.o
obj-$(CONFIG_ZSMALLOC) += zsmalloc.o
+obj-$(CONFIG_Z3FOLD) += z3fold.o
obj-$(CONFIG_GENERIC_EARLY_IOREMAP) += early_ioremap.o
obj-$(CONFIG_CMA) += cma.o
obj-$(CONFIG_MEMORY_BALLOON) += balloon_compaction.o
diff --git a/mm/z3fold.c b/mm/z3fold.c
new file mode 100644
index 000000000000..34917d55d311
--- /dev/null
+++ b/mm/z3fold.c
@@ -0,0 +1,792 @@
+/*
+ * 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
+*****************/
+/*
+ * 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. As one chunk
+ * in allocated page is occupied by z3fold header, NCHUNKS will be calculated
+ * to 63 which shows the max number of free chunks in z3fold page, also there
+ * will be 63 freelists per pool.
+ */
+#define NCHUNKS_ORDER 6
+
+#define CHUNK_SHIFT (PAGE_SHIFT - NCHUNKS_ORDER)
+#define CHUNK_SIZE (1 << CHUNK_SHIFT)
+#define ZHDR_SIZE_ALIGNED CHUNK_SIZE
+#define NCHUNKS ((PAGE_SIZE - ZHDR_SIZE_ALIGNED) >> CHUNK_SHIFT)
+
+#define BUDDY_MASK ((1 << NCHUNKS_ORDER) - 1)
+
+struct z3fold_pool;
+struct z3fold_ops {
+ int (*evict)(struct z3fold_pool *pool, unsigned long handle);
+};
+
+/**
+ * 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.
+ * @buddied: list tracking the z3fold pages that contain 3 buddies;
+ * these z3fold pages are full
+ * @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 buddied;
+ struct list_head lru;
+ u64 pages_nr;
+ const struct z3fold_ops *ops;
+ struct zpool *zpool;
+ const struct zpool_ops *zpool_ops;
+};
+
+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
+ * @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;
+ unsigned short first_chunks;
+ unsigned short middle_chunks;
+ unsigned short last_chunks;
+ unsigned short start_middle;
+ unsigned short first_num:NCHUNKS_ORDER;
+};
+
+/*
+ * Internal z3fold page flags
+ */
+enum z3fold_page_flags {
+ UNDER_RECLAIM = 0,
+ PAGE_HEADLESS,
+ 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(UNDER_RECLAIM, &page->private);
+ clear_bit(PAGE_HEADLESS, &page->private);
+ clear_bit(MIDDLE_CHUNK_MAPPED, &page->private);
+
+ 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 z3fold_header *zhdr)
+{
+ __free_page(virt_to_page(zhdr));
+}
+
+/*
+ * 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);
+}
+
+/* Returns 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 - 1;
+ int nfree_after = zhdr->last_chunks ?
+ 0 : NCHUNKS - 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->buddied);
+ INIT_LIST_HEAD(&pool->lru);
+ 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);
+}
+
+/* Has to be called with lock held */
+static int z3fold_compact_page(struct z3fold_header *zhdr)
+{
+ struct page *page = virt_to_page(zhdr);
+ void *beg = zhdr;
+
+
+ if (!test_bit(MIDDLE_CHUNK_MAPPED, &page->private) &&
+ zhdr->middle_chunks != 0 &&
+ zhdr->first_chunks == 0 && zhdr->last_chunks == 0) {
+ memmove(beg + ZHDR_SIZE_ALIGNED,
+ beg + (zhdr->start_middle << CHUNK_SHIFT),
+ zhdr->middle_chunks << CHUNK_SHIFT);
+ zhdr->first_chunks = zhdr->middle_chunks;
+ zhdr->middle_chunks = 0;
+ zhdr->start_middle = 0;
+ zhdr->first_num++;
+ 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);
+ spin_lock(&pool->lock);
+
+ /* First, try to find an unbuddied z3fold page. */
+ zhdr = NULL;
+ for_each_unbuddied_list(i, chunks) {
+ if (!list_empty(&pool->unbuddied[i])) {
+ zhdr = list_first_entry(&pool->unbuddied[i],
+ struct z3fold_header, buddy);
+ 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 {
+ pr_err("No free chunks in unbuddied\n");
+ WARN_ON(1);
+ continue;
+ }
+ list_del(&zhdr->buddy);
+ goto found;
+ }
+ }
+ bud = FIRST;
+ spin_unlock(&pool->lock);
+ }
+
+ /* Couldn't find unbuddied z3fold page, create new one */
+ page = alloc_page(gfp);
+ if (!page)
+ return -ENOMEM;
+ spin_lock(&pool->lock);
+ pool->pages_nr++;
+ zhdr = init_z3fold_page(page);
+
+ if (bud == HEADLESS) {
+ set_bit(PAGE_HEADLESS, &page->private);
+ goto headless;
+ }
+
+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 + 1;
+ }
+
+ 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]);
+ } else {
+ /* Add to buddied list */
+ list_add(&zhdr->buddy, &pool->buddied);
+ }
+
+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);
+
+ 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;
+
+ spin_lock(&pool->lock);
+ zhdr = handle_to_z3fold_header(handle);
+ page = virt_to_page(zhdr);
+
+ if (test_bit(PAGE_HEADLESS, &page->private)) {
+ /* HEADLESS page stored */
+ bud = HEADLESS;
+ } else {
+ bud = (handle - zhdr->first_num) & BUDDY_MASK;
+
+ 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);
+ spin_unlock(&pool->lock);
+ return;
+ }
+ }
+
+ if (test_bit(UNDER_RECLAIM, &page->private)) {
+ /* z3fold page is under reclaim, reclaim will free */
+ spin_unlock(&pool->lock);
+ return;
+ }
+
+ if (bud != HEADLESS) {
+ /* Remove from existing buddy list */
+ list_del(&zhdr->buddy);
+ }
+
+ if (bud == HEADLESS ||
+ (zhdr->first_chunks == 0 && zhdr->middle_chunks == 0 &&
+ zhdr->last_chunks == 0)) {
+ /* z3fold page is empty, free */
+ list_del(&page->lru);
+ clear_bit(PAGE_HEADLESS, &page->private);
+ free_z3fold_page(zhdr);
+ pool->pages_nr--;
+ } else {
+ z3fold_compact_page(zhdr);
+ /* Add to the unbuddied list */
+ freechunks = num_free_chunks(zhdr);
+ list_add(&zhdr->buddy, &pool->unbuddied[freechunks]);
+ }
+
+ 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 || list_empty(&pool->lru) ||
+ retries == 0) {
+ spin_unlock(&pool->lock);
+ return -EINVAL;
+ }
+ for (i = 0; i < retries; i++) {
+ page = list_last_entry(&pool->lru, struct page, lru);
+ list_del(&page->lru);
+
+ /* Protect z3fold page against free */
+ set_bit(UNDER_RECLAIM, &page->private);
+ zhdr = page_address(page);
+ if (!test_bit(PAGE_HEADLESS, &page->private)) {
+ list_del(&zhdr->buddy);
+ /*
+ * 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);
+ } 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:
+ spin_lock(&pool->lock);
+ clear_bit(UNDER_RECLAIM, &page->private);
+ if ((test_bit(PAGE_HEADLESS, &page->private) && ret == 0) ||
+ (zhdr->first_chunks == 0 && zhdr->last_chunks == 0 &&
+ zhdr->middle_chunks == 0)) {
+ /*
+ * All buddies are now free, free the z3fold page and
+ * return success.
+ */
+ clear_bit(PAGE_HEADLESS, &page->private);
+ free_z3fold_page(zhdr);
+ pool->pages_nr--;
+ spin_unlock(&pool->lock);
+ return 0;
+ } else if (zhdr->first_chunks != 0 &&
+ zhdr->last_chunks != 0 && zhdr->middle_chunks != 0) {
+ /* Full, add to buddied list */
+ list_add(&zhdr->buddy, &pool->buddied);
+ } else if (!test_bit(PAGE_HEADLESS, &page->private)) {
+ z3fold_compact_page(zhdr);
+ /* add to unbuddied list */
+ freechunks = num_free_chunks(zhdr);
+ list_add(&zhdr->buddy, &pool->unbuddied[freechunks]);
+ }
+
+ /* add to beginning of LRU */
+ 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;
+
+ spin_lock(&pool->lock);
+ zhdr = handle_to_z3fold_header(handle);
+ addr = zhdr;
+ page = virt_to_page(zhdr);
+
+ if (test_bit(PAGE_HEADLESS, &page->private))
+ goto out;
+
+ 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;
+ }
+out:
+ spin_unlock(&pool->lock);
+ 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;
+
+ spin_lock(&pool->lock);
+ zhdr = handle_to_z3fold_header(handle);
+ page = virt_to_page(zhdr);
+
+ if (test_bit(PAGE_HEADLESS, &page->private)) {
+ spin_unlock(&pool->lock);
+ return;
+ }
+
+ buddy = handle_to_buddy(handle);
+ if (buddy == MIDDLE)
+ clear_bit(MIDDLE_CHUNK_MAPPED, &page->private);
+ spin_unlock(&pool->lock);
+}
+
+/**
+ * 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. The pool lock need not be
+ * taken to access pages_nr.
+ */
+static u64 z3fold_get_pool_size(struct z3fold_pool *pool)
+{
+ return 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 will fit in one chunk */
+ BUILD_BUG_ON(sizeof(struct z3fold_header) > ZHDR_SIZE_ALIGNED);
+ 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");