Commit af8d417a authored by Dan Streetman's avatar Dan Streetman Committed by Linus Torvalds
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mm/zpool: implement common zpool api to zbud/zsmalloc



Add zpool api.

zpool provides an interface for memory storage, typically of compressed
memory.  Users can select what backend to use; currently the only
implementations are zbud, a low density implementation with up to two
compressed pages per storage page, and zsmalloc, a higher density
implementation with multiple compressed pages per storage page.
Signed-off-by: default avatarDan Streetman <ddstreet@ieee.org>
Tested-by: default avatarSeth Jennings <sjennings@variantweb.net>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Weijie Yang <weijie.yang@samsung.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 99eef8e9
/*
* zpool memory storage api
*
* Copyright (C) 2014 Dan Streetman
*
* This is a common frontend for the zbud and zsmalloc memory
* storage pool implementations. Typically, this is used to
* store compressed memory.
*/
#ifndef _ZPOOL_H_
#define _ZPOOL_H_
struct zpool;
struct zpool_ops {
int (*evict)(struct zpool *pool, unsigned long handle);
};
/*
* Control how a handle is mapped. It will be ignored if the
* implementation does not support it. Its use is optional.
* Note that this does not refer to memory protection, it
* refers to how the memory will be copied in/out if copying
* is necessary during mapping; read-write is the safest as
* it copies the existing memory in on map, and copies the
* changed memory back out on unmap. Write-only does not copy
* in the memory and should only be used for initialization.
* If in doubt, use ZPOOL_MM_DEFAULT which is read-write.
*/
enum zpool_mapmode {
ZPOOL_MM_RW, /* normal read-write mapping */
ZPOOL_MM_RO, /* read-only (no copy-out at unmap time) */
ZPOOL_MM_WO, /* write-only (no copy-in at map time) */
ZPOOL_MM_DEFAULT = ZPOOL_MM_RW
};
struct zpool *zpool_create_pool(char *type, gfp_t gfp, struct zpool_ops *ops);
char *zpool_get_type(struct zpool *pool);
void zpool_destroy_pool(struct zpool *pool);
int zpool_malloc(struct zpool *pool, size_t size, gfp_t gfp,
unsigned long *handle);
void zpool_free(struct zpool *pool, unsigned long handle);
int zpool_shrink(struct zpool *pool, unsigned int pages,
unsigned int *reclaimed);
void *zpool_map_handle(struct zpool *pool, unsigned long handle,
enum zpool_mapmode mm);
void zpool_unmap_handle(struct zpool *pool, unsigned long handle);
u64 zpool_get_total_size(struct zpool *pool);
/**
* struct zpool_driver - driver implementation for zpool
* @type: name of the driver.
* @list: entry in the list of zpool drivers.
* @create: create a new pool.
* @destroy: destroy a pool.
* @malloc: allocate mem from a pool.
* @free: free mem from a pool.
* @shrink: shrink the pool.
* @map: map a handle.
* @unmap: unmap a handle.
* @total_size: get total size of a pool.
*
* This is created by a zpool implementation and registered
* with zpool.
*/
struct zpool_driver {
char *type;
struct module *owner;
atomic_t refcount;
struct list_head list;
void *(*create)(gfp_t gfp, struct zpool_ops *ops);
void (*destroy)(void *pool);
int (*malloc)(void *pool, size_t size, gfp_t gfp,
unsigned long *handle);
void (*free)(void *pool, unsigned long handle);
int (*shrink)(void *pool, unsigned int pages,
unsigned int *reclaimed);
void *(*map)(void *pool, unsigned long handle,
enum zpool_mapmode mm);
void (*unmap)(void *pool, unsigned long handle);
u64 (*total_size)(void *pool);
};
void zpool_register_driver(struct zpool_driver *driver);
int zpool_unregister_driver(struct zpool_driver *driver);
int zpool_evict(void *pool, unsigned long handle);
#endif
......@@ -519,15 +519,17 @@ config CMA_AREAS
If unsure, leave the default value "7".
config ZBUD
tristate
default n
config MEM_SOFT_DIRTY
bool "Track memory changes"
depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS
select PROC_PAGE_MONITOR
help
A special purpose allocator for storing compressed pages.
It is designed to store up to two compressed pages per physical
page. While this design limits storage density, it has simple and
deterministic reclaim properties that make it preferable to a higher
density approach when reclaim will be used.
This option enables memory changes tracking by introducing a
soft-dirty bit on pte-s. This bit it set when someone writes
into a page just as regular dirty bit, but unlike the latter
it can be cleared by hands.
See Documentation/vm/soft-dirty.txt for more details.
config ZSWAP
bool "Compressed cache for swap pages (EXPERIMENTAL)"
......@@ -549,17 +551,22 @@ config ZSWAP
they have not be fully explored on the large set of potential
configurations and workloads that exist.
config MEM_SOFT_DIRTY
bool "Track memory changes"
depends on CHECKPOINT_RESTORE && HAVE_ARCH_SOFT_DIRTY && PROC_FS
select PROC_PAGE_MONITOR
config ZPOOL
tristate "Common API for compressed memory storage"
default n
help
This option enables memory changes tracking by introducing a
soft-dirty bit on pte-s. This bit it set when someone writes
into a page just as regular dirty bit, but unlike the latter
it can be cleared by hands.
Compressed memory storage API. This allows using either zbud or
zsmalloc.
See Documentation/vm/soft-dirty.txt for more details.
config ZBUD
tristate "Low density storage for compressed pages"
default n
help
A special purpose allocator for storing compressed pages.
It is designed to store up to two compressed pages per physical
page. While this design limits storage density, it has simple and
deterministic reclaim properties that make it preferable to a higher
density approach when reclaim will be used.
config ZSMALLOC
tristate "Memory allocator for compressed pages"
......
......@@ -59,6 +59,7 @@ obj-$(CONFIG_DEBUG_KMEMLEAK) += kmemleak.o
obj-$(CONFIG_DEBUG_KMEMLEAK_TEST) += kmemleak-test.o
obj-$(CONFIG_CLEANCACHE) += cleancache.o
obj-$(CONFIG_MEMORY_ISOLATION) += page_isolation.o
obj-$(CONFIG_ZPOOL) += zpool.o
obj-$(CONFIG_ZBUD) += zbud.o
obj-$(CONFIG_ZSMALLOC) += zsmalloc.o
obj-$(CONFIG_GENERIC_EARLY_IOREMAP) += early_ioremap.o
......
/*
* zpool memory storage api
*
* Copyright (C) 2014 Dan Streetman
*
* This is a common frontend for memory storage pool implementations.
* Typically, this is used to store compressed memory.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/list.h>
#include <linux/types.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/module.h>
#include <linux/zpool.h>
struct zpool {
char *type;
struct zpool_driver *driver;
void *pool;
struct zpool_ops *ops;
struct list_head list;
};
static LIST_HEAD(drivers_head);
static DEFINE_SPINLOCK(drivers_lock);
static LIST_HEAD(pools_head);
static DEFINE_SPINLOCK(pools_lock);
/**
* zpool_register_driver() - register a zpool implementation.
* @driver: driver to register
*/
void zpool_register_driver(struct zpool_driver *driver)
{
spin_lock(&drivers_lock);
atomic_set(&driver->refcount, 0);
list_add(&driver->list, &drivers_head);
spin_unlock(&drivers_lock);
}
EXPORT_SYMBOL(zpool_register_driver);
/**
* zpool_unregister_driver() - unregister a zpool implementation.
* @driver: driver to unregister.
*
* Module usage counting is used to prevent using a driver
* while/after unloading, so if this is called from module
* exit function, this should never fail; if called from
* other than the module exit function, and this returns
* failure, the driver is in use and must remain available.
*/
int zpool_unregister_driver(struct zpool_driver *driver)
{
int ret = 0, refcount;
spin_lock(&drivers_lock);
refcount = atomic_read(&driver->refcount);
WARN_ON(refcount < 0);
if (refcount > 0)
ret = -EBUSY;
else
list_del(&driver->list);
spin_unlock(&drivers_lock);
return ret;
}
EXPORT_SYMBOL(zpool_unregister_driver);
/**
* zpool_evict() - evict callback from a zpool implementation.
* @pool: pool to evict from.
* @handle: handle to evict.
*
* This can be used by zpool implementations to call the
* user's evict zpool_ops struct evict callback.
*/
int zpool_evict(void *pool, unsigned long handle)
{
struct zpool *zpool;
spin_lock(&pools_lock);
list_for_each_entry(zpool, &pools_head, list) {
if (zpool->pool == pool) {
spin_unlock(&pools_lock);
if (!zpool->ops || !zpool->ops->evict)
return -EINVAL;
return zpool->ops->evict(zpool, handle);
}
}
spin_unlock(&pools_lock);
return -ENOENT;
}
EXPORT_SYMBOL(zpool_evict);
static struct zpool_driver *zpool_get_driver(char *type)
{
struct zpool_driver *driver;
spin_lock(&drivers_lock);
list_for_each_entry(driver, &drivers_head, list) {
if (!strcmp(driver->type, type)) {
bool got = try_module_get(driver->owner);
if (got)
atomic_inc(&driver->refcount);
spin_unlock(&drivers_lock);
return got ? driver : NULL;
}
}
spin_unlock(&drivers_lock);
return NULL;
}
static void zpool_put_driver(struct zpool_driver *driver)
{
atomic_dec(&driver->refcount);
module_put(driver->owner);
}
/**
* zpool_create_pool() - Create a new zpool
* @type The type of the zpool to create (e.g. zbud, zsmalloc)
* @gfp The GFP flags to use when allocating the pool.
* @ops The optional ops callback.
*
* This creates a new zpool of the specified type. The gfp flags will be
* used when allocating memory, if the implementation supports it. If the
* ops param is NULL, then the created zpool will not be shrinkable.
*
* Implementations must guarantee this to be thread-safe.
*
* Returns: New zpool on success, NULL on failure.
*/
struct zpool *zpool_create_pool(char *type, gfp_t gfp, struct zpool_ops *ops)
{
struct zpool_driver *driver;
struct zpool *zpool;
pr_info("creating pool type %s\n", type);
driver = zpool_get_driver(type);
if (!driver) {
request_module(type);
driver = zpool_get_driver(type);
}
if (!driver) {
pr_err("no driver for type %s\n", type);
return NULL;
}
zpool = kmalloc(sizeof(*zpool), gfp);
if (!zpool) {
pr_err("couldn't create zpool - out of memory\n");
zpool_put_driver(driver);
return NULL;
}
zpool->type = driver->type;
zpool->driver = driver;
zpool->pool = driver->create(gfp, ops);
zpool->ops = ops;
if (!zpool->pool) {
pr_err("couldn't create %s pool\n", type);
zpool_put_driver(driver);
kfree(zpool);
return NULL;
}
pr_info("created %s pool\n", type);
spin_lock(&pools_lock);
list_add(&zpool->list, &pools_head);
spin_unlock(&pools_lock);
return zpool;
}
/**
* zpool_destroy_pool() - Destroy a zpool
* @pool The zpool to destroy.
*
* Implementations must guarantee this to be thread-safe,
* however only when destroying different pools. The same
* pool should only be destroyed once, and should not be used
* after it is destroyed.
*
* This destroys an existing zpool. The zpool should not be in use.
*/
void zpool_destroy_pool(struct zpool *zpool)
{
pr_info("destroying pool type %s\n", zpool->type);
spin_lock(&pools_lock);
list_del(&zpool->list);
spin_unlock(&pools_lock);
zpool->driver->destroy(zpool->pool);
zpool_put_driver(zpool->driver);
kfree(zpool);
}
/**
* zpool_get_type() - Get the type of the zpool
* @pool The zpool to check
*
* This returns the type of the pool.
*
* Implementations must guarantee this to be thread-safe.
*
* Returns: The type of zpool.
*/
char *zpool_get_type(struct zpool *zpool)
{
return zpool->type;
}
/**
* zpool_malloc() - Allocate memory
* @pool The zpool to allocate from.
* @size The amount of memory to allocate.
* @gfp The GFP flags to use when allocating memory.
* @handle Pointer to the handle to set
*
* This allocates the requested amount of memory from the pool.
* The gfp flags will be used when allocating memory, if the
* implementation supports it. The provided @handle will be
* set to the allocated object handle.
*
* Implementations must guarantee this to be thread-safe.
*
* Returns: 0 on success, negative value on error.
*/
int zpool_malloc(struct zpool *zpool, size_t size, gfp_t gfp,
unsigned long *handle)
{
return zpool->driver->malloc(zpool->pool, size, gfp, handle);
}
/**
* zpool_free() - Free previously allocated memory
* @pool The zpool that allocated the memory.
* @handle The handle to the memory to free.
*
* This frees previously allocated memory. This does not guarantee
* that the pool will actually free memory, only that the memory
* in the pool will become available for use by the pool.
*
* Implementations must guarantee this to be thread-safe,
* however only when freeing different handles. The same
* handle should only be freed once, and should not be used
* after freeing.
*/
void zpool_free(struct zpool *zpool, unsigned long handle)
{
zpool->driver->free(zpool->pool, handle);
}
/**
* zpool_shrink() - Shrink the pool size
* @pool The zpool to shrink.
* @pages The number of pages to shrink the pool.
* @reclaimed The number of pages successfully evicted.
*
* This attempts to shrink the actual memory size of the pool
* by evicting currently used handle(s). If the pool was
* created with no zpool_ops, or the evict call fails for any
* of the handles, this will fail. If non-NULL, the @reclaimed
* parameter will be set to the number of pages reclaimed,
* which may be more than the number of pages requested.
*
* Implementations must guarantee this to be thread-safe.
*
* Returns: 0 on success, negative value on error/failure.
*/
int zpool_shrink(struct zpool *zpool, unsigned int pages,
unsigned int *reclaimed)
{
return zpool->driver->shrink(zpool->pool, pages, reclaimed);
}
/**
* zpool_map_handle() - Map a previously allocated handle into memory
* @pool The zpool that the handle was allocated from
* @handle The handle to map
* @mm How the memory should be mapped
*
* This maps a previously allocated handle into memory. The @mm
* param indicates to the implementation how the memory will be
* used, i.e. read-only, write-only, read-write. If the
* implementation does not support it, the memory will be treated
* as read-write.
*
* This may hold locks, disable interrupts, and/or preemption,
* and the zpool_unmap_handle() must be called to undo those
* actions. The code that uses the mapped handle should complete
* its operatons on the mapped handle memory quickly and unmap
* as soon as possible. As the implementation may use per-cpu
* data, multiple handles should not be mapped concurrently on
* any cpu.
*
* Returns: A pointer to the handle's mapped memory area.
*/
void *zpool_map_handle(struct zpool *zpool, unsigned long handle,
enum zpool_mapmode mapmode)
{
return zpool->driver->map(zpool->pool, handle, mapmode);
}
/**
* zpool_unmap_handle() - Unmap a previously mapped handle
* @pool The zpool that the handle was allocated from
* @handle The handle to unmap
*
* This unmaps a previously mapped handle. Any locks or other
* actions that the implementation took in zpool_map_handle()
* will be undone here. The memory area returned from
* zpool_map_handle() should no longer be used after this.
*/
void zpool_unmap_handle(struct zpool *zpool, unsigned long handle)
{
zpool->driver->unmap(zpool->pool, handle);
}
/**
* zpool_get_total_size() - The total size of the pool
* @pool The zpool to check
*
* This returns the total size in bytes of the pool.
*
* Returns: Total size of the zpool in bytes.
*/
u64 zpool_get_total_size(struct zpool *zpool)
{
return zpool->driver->total_size(zpool->pool);
}
static int __init init_zpool(void)
{
pr_info("loaded\n");
return 0;
}
static void __exit exit_zpool(void)
{
pr_info("unloaded\n");
}
module_init(init_zpool);
module_exit(exit_zpool);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Dan Streetman <ddstreet@ieee.org>");
MODULE_DESCRIPTION("Common API for compressed memory storage");
......@@ -240,7 +240,6 @@ struct mapping_area {
enum zs_mapmode vm_mm; /* mapping mode */
};
/* per-cpu VM mapping areas for zspage accesses that cross page boundaries */
static DEFINE_PER_CPU(struct mapping_area, zs_map_area);
......
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