linux/mm/zpool.c
Ganesh Mahendran 3eba0c6a56 mm/zpool: add name argument to create zpool
Currently the underlay of zpool: zsmalloc/zbud, do not know who creates
them.  There is not a method to let zsmalloc/zbud find which caller they
belong to.

Now we want to add statistics collection in zsmalloc.  We need to name the
debugfs dir for each pool created.  The way suggested by Minchan Kim is to
use a name passed by caller(such as zram) to create the zsmalloc pool.

    /sys/kernel/debug/zsmalloc/zram0

This patch adds an argument `name' to zs_create_pool() and other related
functions.

Signed-off-by: Ganesh Mahendran <opensource.ganesh@gmail.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Seth Jennings <sjennings@variantweb.net>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Dan Streetman <ddstreet@ieee.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 18:54:12 -08:00

367 lines
9.6 KiB
C

/*
* 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)
* @name The name of the zpool (e.g. zram0, zswap)
* @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, char *name, 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("zpool-%s", 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(name, 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");