On Fri, Dec 2, 2022 at 5:01 AM Ananda Badmaev <a.badmaev@xxxxxxxxxxxx> wrote:
>
> Zblock stores a fixed number of compressed objects per zblock block.
> These blocks consist of several consecutive physical pages (1/2/4/8) and
> are arranged in linked lists.
> The range from 0 to PAGE_SIZE is divided into the number of intervals
> corresponding to the number of lists and each list only operates objects
> of size from its interval. Thus the block lists are isolated from each
> other, which makes it possible to simultaneously perform actions with
> several objects from different lists.
> With zblock, it is possible to densely arrange objects of various sizes
> resulting in low internal fragmentation. Also this allocator tries to fill
> incomplete blocks instead of adding new ones thus in many cases providing a
> compression ratio substantially higher than z3fold and zbud.
> Zblock does not require MMU and also is superior to zsmalloc with
> regard to the worst execution times, thus allowing for better response time
> and real-time characteristics of the whole system.
>
> Signed-off-by: Ananda Badmaev <a.badmaev@xxxxxxxxxxxx>
Signed-off-by: Vitaly Wool <vitaly.wool@xxxxxxxxxxxx>
> ---
>
> v2: fixed compiler warnings
>
> v3: added documentation and const modifier to struct tree_descr
>
> v4:
> - fixed gfp flags for block allocation
> - fixed potential memory leak when allocating blocks
> - resolved some issues with code style and warnings from checkpatch
> (except warning about single line config symbol description)
> - moved test results from documentation to changelog
>
> v5:
> - "direct" handle mapping and use of linked lists instead of red-black
> trees resulting in faster operations and a bit simpler code
> - renamed ztree -> zblock
> - edited various comments and descriptions
>
> v6:
> - fixed tabs (tab size 8 instead of 4)
> - evict also pages that have not been mapped
>
> v7:
> - fixed potential unsigned overflow of block_type in zblock_reclaim_block
> - added check on the ability to store objects of size PAGE_SIZE
> at pool creation time
> - added zblock into Documentation/mm/index.rst
>
> v8:
> - fixed typo and improved the wording in zblock.rst and commit description
>
> v9:
> - rephrased the cover message and added extra details to Kconfig description
>
> Documentation/mm/index.rst | 1 +
> Documentation/mm/zblock.rst | 31 ++
> MAINTAINERS | 7 +
> mm/Kconfig | 18 +
> mm/Makefile | 1 +
> mm/zblock.c | 642 ++++++++++++++++++++++++++++++++++++
> 6 files changed, 700 insertions(+)
> create mode 100644 Documentation/mm/zblock.rst
> create mode 100644 mm/zblock.c
>
> diff --git a/Documentation/mm/index.rst b/Documentation/mm/index.rst
> index 4aa12b8be278..3e538e098eb6 100644
> --- a/Documentation/mm/index.rst
> +++ b/Documentation/mm/index.rst
> @@ -66,4 +66,5 @@ above structured documentation, or deleted if it has served its purpose.
> vmalloced-kernel-stacks
> vmemmap_dedup
> z3fold
> + zblock
> zsmalloc
> diff --git a/Documentation/mm/zblock.rst b/Documentation/mm/zblock.rst
> new file mode 100644
> index 000000000000..7098f1b5e5dc
> --- /dev/null
> +++ b/Documentation/mm/zblock.rst
> @@ -0,0 +1,31 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +.. _zblock:
> +
> +======
> +zblock
> +======
> +
> +Zblock stores a fixed number of compressed objects per block. These blocks
> +consist of several consecutive physical pages (from 1 to 8) and are arranged
> +in lists. The range from 0 to PAGE_SIZE is divided into the number of intervals
> +corresponding to the number of lists and these only operate on objects of size
> +from its interval. Thus the block lists are isolated from each other, which
> +makes it possible to simultaneously perform actions with several objects
> +from different lists.
> +
> +With zblock, it is possible to densely arrange objects of various sizes,
> +resulting in low internal fragmentation. Also this allocator tries to fill
> +incomplete blocks instead of adding new ones. As a result, in many cases it
> +provides a compression ratio substantially higher than z3fold and zbud. Zblock
> +does not require MMU and also is superior to zsmalloc with regard to the worst
> +execution times, thus allowing for better response time and real-time
> +characteristics of the whole system.
> +
> +Like similar allocation method from z3fold and zsmalloc, zblock_alloc() does
> +not return a dereferenceable pointer. Instead, it returns an unsigned long
> +handle which encodes actual location of the allocated object.
> +
> +Unlike zbud and z3fold, zblock works well with objects of various sizes -
> +including but not limited to highly compressed and poorly compressed, as well
> +as cases where both object types exist.
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 69565ac0c224..75499177dceb 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -22729,6 +22729,13 @@ L: linux-mm@xxxxxxxxx
> S: Maintained
> F: mm/z3fold.c
>
> +ZBLOCK COMPRESSED PAGE ALLOCATOR
> +M: Ananda Badmaev <a.badmaev@xxxxxxxxxxxx>
> +M: Vitaly Wool <vitaly.wool@xxxxxxxxxxxx>
> +L: linux-mm@xxxxxxxxx
> +S: Maintained
> +F: mm/zblock.c
> +
> ZD1211RW WIRELESS DRIVER
> M: Ulrich Kunitz <kune@xxxxxxxxxxxxxx>
> L: linux-wireless@xxxxxxxxxxxxxxx
> diff --git a/mm/Kconfig b/mm/Kconfig
> index 57e1d8c5b505..dd138db3c029 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -143,6 +143,12 @@ config ZSWAP_ZPOOL_DEFAULT_ZSMALLOC
> select ZSMALLOC
> help
> Use the zsmalloc allocator as the default allocator.
> +
> +config ZSWAP_ZPOOL_DEFAULT_ZBLOCK
> + bool "zblock"
> + select ZBLOCK
> + help
> + Use the zblock allocator as the default allocator.
> endchoice
>
> config ZSWAP_ZPOOL_DEFAULT
> @@ -151,6 +157,7 @@ config ZSWAP_ZPOOL_DEFAULT
> default "zbud" if ZSWAP_ZPOOL_DEFAULT_ZBUD
> default "z3fold" if ZSWAP_ZPOOL_DEFAULT_Z3FOLD
> default "zsmalloc" if ZSWAP_ZPOOL_DEFAULT_ZSMALLOC
> + default "zblock" if ZSWAP_ZPOOL_DEFAULT_ZBLOCK
> default ""
>
> config ZBUD
> @@ -181,6 +188,17 @@ config ZSMALLOC
> pages of various compression levels efficiently. It achieves
> the highest storage density with the least amount of fragmentation.
>
> +config ZBLOCK
> + tristate "Simple block allocator (zblock)"
> + depends on ZPOOL
> + help
> + A special purpose allocator for storing compressed pages.
> + zblock provides fast read/write, limited worst case time for
> + operations and good compression ratio in most scenarios. It's a
> + good fit for small RAM devices due to its simplicity and small code
> + size. Generally faster than zsmalloc (by 2-7%) and more scalable but
> + provides worse compression ratio than zsmalloc (by about 10%).
> +
> config ZSMALLOC_STAT
> bool "Export zsmalloc statistics"
> depends on ZSMALLOC
> diff --git a/mm/Makefile b/mm/Makefile
> index 8e105e5b3e29..f2c89390542c 100644
> --- a/mm/Makefile
> +++ b/mm/Makefile
> @@ -114,6 +114,7 @@ obj-$(CONFIG_ZPOOL) += zpool.o
> obj-$(CONFIG_ZBUD) += zbud.o
> obj-$(CONFIG_ZSMALLOC) += zsmalloc.o
> obj-$(CONFIG_Z3FOLD) += z3fold.o
> +obj-$(CONFIG_ZBLOCK) += zblock.o
> obj-$(CONFIG_GENERIC_EARLY_IOREMAP) += early_ioremap.o
> obj-$(CONFIG_CMA) += cma.o
> obj-$(CONFIG_MEMORY_BALLOON) += balloon_compaction.o
> diff --git a/mm/zblock.c b/mm/zblock.c
> new file mode 100644
> index 000000000000..4767a367fa71
> --- /dev/null
> +++ b/mm/zblock.c
> @@ -0,0 +1,642 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * zblock.c
> + *
> + * Author: Ananda Badmaev <a.badmaev@xxxxxxxxxxxx>
> + * Copyright (C) 2022, Konsulko AB.
> + *
> + * This implementation is based on z3fold written by Vitaly Wool.
> + * Zblock is a small object allocator with the intention to serve as a
> + * zpool backend. It operates on page blocks which consist of number
> + * of physical pages being a power of 2 and store integer number of
> + * compressed pages per block which results in determinism and simplicity.
> + *
> + * zblock 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>
> +
> +#define SLOT_FREE 0
> +#define SLOT_OCCUPIED 1
> +#define SLOT_MAPPED 2
> +#define SLOT_UNMAPPED 3
> +
> +#define SLOT_BITS 5
> +#define MAX_SLOTS (1 << SLOT_BITS)
> +#define SLOT_MASK ((0x1UL << SLOT_BITS) - 1)
> +
> +#define BLOCK_DATA_SIZE(order) ((PAGE_SIZE << order) - sizeof(struct zblock_block))
> +#define SLOT_SIZE(nslots, order) (round_down((BLOCK_DATA_SIZE(order) / nslots), sizeof(long)))
> +
> +#define BLOCK_CACHE_SIZE 32
> +
> +struct zblock_pool;
> +
> +struct zblock_ops {
> + int (*evict)(struct zblock_pool *pool, unsigned long handle);
> +};
> +
> +/**
> + * struct zblock_block - block metadata
> + * Block consists of several (1/2/4/8) pages and contains fixed
> + * integer number of slots for allocating compressed pages.
> + *
> + * lock: protects block
> + * block_node: links block into the relevant list in the pool
> + * slot_info: contains data about free/occupied slots
> + * free_slots: number of free slots in the block
> + * under_reclaim: if true shows that block is being evicted
> + */
> +struct zblock_block {
> + spinlock_t lock;
> + struct list_head block_node;
> + u8 slot_info[MAX_SLOTS];
> + unsigned int free_slots;
> + bool under_reclaim;
> +};
> +/**
> + * struct block_desc - general metadata for block lists
> + * Each block list stores only blocks of corresponding type which means
> + * that all blocks in it have the same number and size of slots.
> + * All slots are aligned to size of long.
> + *
> + * slot_size: size of slot for this list
> + * slots_per_block: number of slots per block for this list
> + * order: order for __get_free_pages
> + */
> +static const struct block_desc {
> + const unsigned int slot_size;
> + const unsigned short slots_per_block;
> + const unsigned short order;
> +} block_desc[] = {
> + { SLOT_SIZE(32, 0), 32, 0 },
> + { SLOT_SIZE(22, 0), 22, 0 },
> + { SLOT_SIZE(17, 0), 17, 0 },
> + { SLOT_SIZE(13, 0), 13, 0 },
> + { SLOT_SIZE(11, 0), 11, 0 },
> + { SLOT_SIZE(9, 0), 9, 0 },
> + { SLOT_SIZE(8, 0), 8, 0 },
> + { SLOT_SIZE(14, 1), 14, 1 },
> + { SLOT_SIZE(12, 1), 12, 1 },
> + { SLOT_SIZE(11, 1), 11, 1 },
> + { SLOT_SIZE(10, 1), 10, 1 },
> + { SLOT_SIZE(9, 1), 9, 1 },
> + { SLOT_SIZE(8, 1), 8, 1 },
> + { SLOT_SIZE(15, 2), 15, 2 },
> + { SLOT_SIZE(14, 2), 14, 2 },
> + { SLOT_SIZE(13, 2), 13, 2 },
> + { SLOT_SIZE(12, 2), 12, 2 },
> + { SLOT_SIZE(11, 2), 11, 2 },
> + { SLOT_SIZE(10, 2), 10, 2 },
> + { SLOT_SIZE(9, 2), 9, 2 },
> + { SLOT_SIZE(8, 2), 8, 2 },
> + { SLOT_SIZE(15, 3), 15, 3 },
> + { SLOT_SIZE(14, 3), 14, 3 },
> + { SLOT_SIZE(13, 3), 13, 3 },
> + { SLOT_SIZE(12, 3), 12, 3 },
> + { SLOT_SIZE(11, 3), 11, 3 },
> + { SLOT_SIZE(10, 3), 10, 3 },
> + { SLOT_SIZE(9, 3), 9, 3 },
> + { SLOT_SIZE(7, 3), 7, 3 }
> +};
> +
> +/**
> + * struct block_list - stores metadata of particular list
> + * lock: protects list
> + * head: head of this list
> + * block_cache: blocks with free slots
> + * block_count: total number of blocks in the list
> + */
> +struct block_list {
> + spinlock_t lock;
> + struct list_head head;
> + struct zblock_block *block_cache[BLOCK_CACHE_SIZE];
> + unsigned long block_count;
> +};
> +
> +/**
> + * struct zblock_pool - stores metadata for each zblock pool
> + * @block_lists: array of block lists
> + * @ops: pointer to a structure of user defined operations specified at
> + * pool creation time.
> + * @zpool: zpool driver
> + * @zpool_ops: zpool operations structure with an evict callback
> + * @alloc_flag: protects block allocation from memory leak
> + *
> + * This structure is allocated at pool creation time and maintains metadata
> + * for a particular zblock pool.
> + */
> +struct zblock_pool {
> + struct block_list block_lists[ARRAY_SIZE(block_desc)];
> + const struct zblock_ops *ops;
> + struct zpool *zpool;
> + const struct zpool_ops *zpool_ops;
> + atomic_t alloc_flag;
> +};
> +
> +/*****************
> + * Helpers
> + *****************/
> +
> +static void cache_insert_block(struct zblock_block *block, struct block_list *list)
> +{
> + unsigned int i, min_free_slots, min_index;
> +
> + min_free_slots = MAX_SLOTS;
> + for (i = 0; i < BLOCK_CACHE_SIZE; i++) {
> + if (!list->block_cache[i] || !(list->block_cache[i])->free_slots) {
> + list->block_cache[i] = block;
> + return;
> + }
> + if ((list->block_cache[i])->free_slots < min_free_slots) {
> + min_free_slots = (list->block_cache[i])->free_slots;
> + min_index = i;
> + }
> + }
> + list->block_cache[min_index] = block;
> +}
> +
> +static struct zblock_block *cache_find_block(struct block_list *list)
> +{
> + int i;
> +
> + for (i = 0; i < BLOCK_CACHE_SIZE; i++) {
> + if (list->block_cache[i] && (list->block_cache[i])->free_slots)
> + return list->block_cache[i];
> + }
> + return NULL;
> +}
> +
> +static int is_in_cache(struct zblock_block *block, struct block_list *list)
> +{
> + int i;
> +
> + for (i = 0; i < BLOCK_CACHE_SIZE; i++) {
> + if (block == list->block_cache[i])
> + return i;
> + }
> + return -1;
> +}
> +
> +/*
> + * allocate new block and add it to corresponding block list
> + */
> +static struct zblock_block *alloc_block(struct zblock_pool *pool,
> + int block_type, gfp_t gfp)
> +{
> + struct zblock_block *block;
> + struct block_list *list;
> +
> + block = (void *)__get_free_pages(gfp, block_desc[block_type].order);
> + if (!block)
> + return NULL;
> +
> + list = &(pool->block_lists)[block_type];
> +
> + /* init block data */
> + spin_lock_init(&block->lock);
> + memset(block->slot_info, SLOT_FREE, block_desc[block_type].slots_per_block);
> + block->free_slots = block_desc[block_type].slots_per_block;
> + block->under_reclaim = false;
> +
> + spin_lock(&list->lock);
> + /* inserting block into list */
> + INIT_LIST_HEAD(&block->block_node);
> + list_add(&block->block_node, &list->head);
> + cache_insert_block(block, list);
> + list->block_count++;
> + spin_unlock(&list->lock);
> + return block;
> +}
> +
> +/*
> + * Encodes the handle of a particular slot in the pool using metadata
> + */
> +static inline unsigned long metadata_to_handle(struct zblock_block *block,
> + unsigned int block_type, unsigned int slot)
> +{
> + return (unsigned long)(block) + (block_type << SLOT_BITS) + slot;
> +}
> +
> +/* Returns block, block type and slot in the pool corresponding to handle */
> +static inline struct zblock_block *handle_to_metadata(unsigned long handle,
> + unsigned int *block_type, unsigned int *slot)
> +{
> + *block_type = (handle & (PAGE_SIZE - 1)) >> SLOT_BITS;
> + *slot = handle & SLOT_MASK;
> + return (struct zblock_block *)(handle & PAGE_MASK);
> +}
> +
> +
> +/*****************
> + * API Functions
> + *****************/
> +/**
> + * zblock_create_pool() - create a new zblock pool
> + * @gfp: gfp flags when allocating the zblock pool structure
> + * @ops: user-defined operations for the zblock pool
> + *
> + * Return: pointer to the new zblock pool or NULL if the metadata allocation
> + * failed.
> + */
> +static struct zblock_pool *zblock_create_pool(gfp_t gfp, const struct zblock_ops *ops)
> +{
> + struct zblock_pool *pool;
> + struct block_list *list;
> + int i, j, arr_sz;
> +
> + pool = kmalloc(sizeof(struct zblock_pool), gfp);
> + if (!pool)
> + return NULL;
> +
> + arr_sz = ARRAY_SIZE(block_desc);
> + if (block_desc[arr_sz - 1].slot_size < PAGE_SIZE)
> + return NULL;
> +
> + /* init each block list */
> + for (i = 0; i < arr_sz; i++) {
> + list = &(pool->block_lists)[i];
> + spin_lock_init(&list->lock);
> + INIT_LIST_HEAD(&list->head);
> + for (j = 0; j < BLOCK_CACHE_SIZE; j++)
> + list->block_cache[j] = NULL;
> + list->block_count = 0;
> + }
> + pool->ops = ops;
> + atomic_set(&pool->alloc_flag, 0);
> + return pool;
> +}
> +
> +/**
> + * zblock_destroy_pool() - destroys an existing zblock pool
> + * @pool: the zblock pool to be destroyed
> + *
> + */
> +static void zblock_destroy_pool(struct zblock_pool *pool)
> +{
> + kfree(pool);
> +}
> +
> +
> +/**
> + * zblock_alloc() - allocates a slot of appropriate size
> + * @pool: zblock 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
> + *
> + * 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 slot.
> + */
> +static int zblock_alloc(struct zblock_pool *pool, size_t size, gfp_t gfp,
> + unsigned long *handle)
> +{
> + unsigned int block_type, slot;
> + struct zblock_block *block;
> + struct block_list *list;
> +
> + if (!size)
> + return -EINVAL;
> +
> + if (size > PAGE_SIZE)
> + return -ENOSPC;
> +
> + /* find basic block type with suitable slot size */
> + for (block_type = 0; block_type < ARRAY_SIZE(block_desc); block_type++) {
> + if (size <= block_desc[block_type].slot_size)
> + break;
> + }
> + list = &(pool->block_lists[block_type]);
> +
> +check:
> + spin_lock(&list->lock);
> + /* check if there are free slots in cache */
> + block = cache_find_block(list);
> + if (block)
> + goto found;
> + spin_unlock(&list->lock);
> +
> + /* not found block with free slots try to allocate new empty block */
> + if (atomic_cmpxchg(&pool->alloc_flag, 0, 1))
> + goto check;
> + block = alloc_block(pool, block_type, gfp & ~(__GFP_HIGHMEM | __GFP_MOVABLE));
> + if (block) {
> + spin_lock(&list->lock);
> + goto found;
> + }
> + atomic_set(&pool->alloc_flag, 0);
> + return -ENOMEM;
> +
> +found:
> + spin_lock(&block->lock);
> + block->free_slots--;
> + spin_unlock(&list->lock);
> + /* find the first free slot in block */
> + for (slot = 0; slot < block_desc[block_type].slots_per_block; slot++) {
> + if (block->slot_info[slot] == SLOT_FREE)
> + break;
> + }
> + block->slot_info[slot] = SLOT_OCCUPIED;
> + spin_unlock(&block->lock);
> + *handle = metadata_to_handle(block, block_type, slot);
> + atomic_set(&pool->alloc_flag, 0);
> + return 0;
> +}
> +
> +/**
> + * zblock_free() - frees the allocation associated with the given handle
> + * @pool: pool in which the allocation resided
> + * @handle: handle associated with the allocation returned by zblock_alloc()
> + *
> + */
> +static void zblock_free(struct zblock_pool *pool, unsigned long handle)
> +{
> + unsigned int slot, block_type;
> + struct zblock_block *block;
> + struct block_list *list;
> + int i;
> +
> + block = handle_to_metadata(handle, &block_type, &slot);
> + list = &(pool->block_lists[block_type]);
> +
> + if (block->under_reclaim)
> + return;
> + spin_lock(&list->lock);
> + i = is_in_cache(block, list);
> + block->free_slots++;
> + /* if all slots in block are empty delete whole block */
> + if (block->free_slots == block_desc[block_type].slots_per_block) {
> + list_del(&block->block_node);
> + list->block_count--;
> +
> + /* if cached block to be deleted */
> + if (i != -1)
> + list->block_cache[i] = NULL;
> + spin_unlock(&list->lock);
> + free_pages((unsigned long)block, block_desc[block_type].order);
> + return;
> + }
> + /* if block is not cached update cache */
> + if (i == -1)
> + cache_insert_block(block, list);
> +
> + spin_lock(&block->lock);
> + spin_unlock(&list->lock);
> + block->slot_info[slot] = SLOT_FREE;
> + spin_unlock(&block->lock);
> +}
> +
> +/**
> + * zblock_reclaim_block() - evicts allocations from block and frees it
> + * @pool: pool from which a block will attempt to be evicted
> + *
> + * Returns: pages reclaimed count if block is successfully freed
> + * otherwise -EINVAL if there are no blocks to evict
> + */
> +static int zblock_reclaim_block(struct zblock_pool *pool)
> +{
> + struct zblock_block *block;
> + struct block_list *list;
> + unsigned long handle;
> + int ret, i, reclaimed, block_type, slot;
> +
> + /* start with list storing blocks with the worst compression and try
> + * to evict the first added (oldest) block in this list
> + */
> + for (block_type = ARRAY_SIZE(block_desc) - 1; block_type >= 0; --block_type) {
> + list = &(pool->block_lists[block_type]);
> + spin_lock(&list->lock);
> +
> + /* find the oldest block in list */
> + block = list_last_entry(&list->head, struct zblock_block, block_node);
> +
> + if (!block) {
> + spin_unlock(&list->lock);
> + continue;
> + }
> + i = is_in_cache(block, list);
> + /* skip iteration if this block is cached */
> + if (i != -1) {
> + spin_unlock(&list->lock);
> + continue;
> + }
> + block->under_reclaim = true;
> + spin_unlock(&list->lock);
> + reclaimed = 0;
> +
> + /* try to evict all OCCUPIED and UNMAPPED slots in block */
> + for (slot = 0; slot < block_desc[block_type].slots_per_block; ++slot) {
> + if (block->slot_info[slot] == SLOT_OCCUPIED ||
> + block->slot_info[slot] == SLOT_UNMAPPED) {
> + handle = metadata_to_handle(block, block_type, slot);
> + ret = pool->ops->evict(pool, handle);
> + if (ret)
> + break;
> +
> + ++reclaimed;
> + spin_lock(&block->lock);
> + block->slot_info[slot] = SLOT_FREE;
> + spin_unlock(&block->lock);
> + block->free_slots++;
> + }
> + }
> + spin_lock(&list->lock);
> + /* some occupied slots remained - insert block */
> + if (block->free_slots != block_desc[block_type].slots_per_block) {
> + block->under_reclaim = false;
> + cache_insert_block(block, list);
> + spin_unlock(&list->lock);
> + } else {
> + /* all slots are free - delete this block */
> + list_del(&block->block_node);
> + list->block_count--;
> + spin_unlock(&list->lock);
> + free_pages((unsigned long)block, block_desc[block_type].order);
> + }
> + if (reclaimed != 0)
> + return reclaimed;
> + return -EAGAIN;
> + }
> + return -EINVAL;
> +}
> +
> +
> +/**
> + * zblock_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
> + *
> + *
> + * Returns: a pointer to the mapped allocation
> + */
> +static void *zblock_map(struct zblock_pool *pool, unsigned long handle)
> +{
> + unsigned int block_type, slot;
> + struct zblock_block *block;
> +
> + block = handle_to_metadata(handle, &block_type, &slot);
> + spin_lock(&block->lock);
> + block->slot_info[slot] = SLOT_MAPPED;
> + spin_unlock(&block->lock);
> + return (void *)(block + 1) + slot * block_desc[block_type].slot_size;
> +}
> +
> +/**
> + * zblock_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 zblock_unmap(struct zblock_pool *pool, unsigned long handle)
> +{
> + unsigned int block_type, slot;
> + struct zblock_block *block;
> +
> + block = handle_to_metadata(handle, &block_type, &slot);
> + spin_lock(&block->lock);
> + block->slot_info[slot] = SLOT_UNMAPPED;
> + spin_unlock(&block->lock);
> +}
> +
> +/**
> + * zblock_get_pool_size() - gets the zblock pool size in bytes
> + * @pool: pool whose size is being queried
> + *
> + * Returns: size in bytes of the given pool.
> + */
> +static u64 zblock_get_pool_size(struct zblock_pool *pool)
> +{
> + u64 total_size;
> + int i;
> +
> + total_size = 0;
> + for (i = 0; i < ARRAY_SIZE(block_desc); i++) {
> + total_size += (pool->block_lists)[i].block_count
> + * (PAGE_SIZE << block_desc[i].order);
> + }
> + return total_size;
> +}
> +
> +/*****************
> + * zpool
> + ****************/
> +
> +static int zblock_zpool_evict(struct zblock_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 zblock_ops zblock_zpool_ops = {
> + .evict = zblock_zpool_evict
> +};
> +
> +static void *zblock_zpool_create(const char *name, gfp_t gfp,
> + const struct zpool_ops *zpool_ops,
> + struct zpool *zpool)
> +{
> + struct zblock_pool *pool;
> +
> + pool = zblock_create_pool(gfp, &zblock_zpool_ops);
> + if (pool) {
> + pool->zpool = zpool;
> + pool->zpool_ops = zpool_ops;
> + }
> + return pool;
> +}
> +
> +static void zblock_zpool_destroy(void *pool)
> +{
> + zblock_destroy_pool(pool);
> +}
> +
> +static int zblock_zpool_malloc(void *pool, size_t size, gfp_t gfp,
> + unsigned long *handle)
> +{
> + return zblock_alloc(pool, size, gfp, handle);
> +}
> +
> +static void zblock_zpool_free(void *pool, unsigned long handle)
> +{
> + zblock_free(pool, handle);
> +}
> +
> +static int zblock_zpool_shrink(void *pool, unsigned int pages,
> + unsigned int *reclaimed)
> +{
> + unsigned int total = 0;
> + int ret = -EINVAL;
> +
> + while (total < pages) {
> + ret = zblock_reclaim_block(pool);
> + if (ret < 0)
> + break;
> + total += ret;
> + }
> + if (reclaimed)
> + *reclaimed = total;
> +
> + return ret;
> +}
> +
> +static void *zblock_zpool_map(void *pool, unsigned long handle,
> + enum zpool_mapmode mm)
> +{
> + return zblock_map(pool, handle);
> +}
> +
> +static void zblock_zpool_unmap(void *pool, unsigned long handle)
> +{
> + zblock_unmap(pool, handle);
> +}
> +
> +static u64 zblock_zpool_total_size(void *pool)
> +{
> + return zblock_get_pool_size(pool);
> +}
> +
> +static struct zpool_driver zblock_zpool_driver = {
> + .type = "zblock",
> + .owner = THIS_MODULE,
> + .create = zblock_zpool_create,
> + .destroy = zblock_zpool_destroy,
> + .malloc = zblock_zpool_malloc,
> + .free = zblock_zpool_free,
> + .shrink = zblock_zpool_shrink,
> + .map = zblock_zpool_map,
> + .unmap = zblock_zpool_unmap,
> + .total_size = zblock_zpool_total_size,
> +};
> +
> +MODULE_ALIAS("zpool-zblock");
> +
> +static int __init init_zblock(void)
> +{
> + pr_info("loaded\n");
> + zpool_register_driver(&zblock_zpool_driver);
> + return 0;
> +}
> +
> +static void __exit exit_zblock(void)
> +{
> + zpool_unregister_driver(&zblock_zpool_driver);
> + pr_info("unloaded\n");
> +}
> +
> +module_init(init_zblock);
> +module_exit(exit_zblock);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Ananda Badmaeb <a.badmaev@xxxxxxxxxxxx>");
> +MODULE_DESCRIPTION("Block allocator for compressed pages");
> --
> 2.34.1
>
