mm/zpool.c - LeafOS-Devices/android_kernel_samsung_gta4xl - Gitiles

 /*
  * 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;
 	const 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);

 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,
 		const struct zpool_ops *ops)
 {
 	struct zpool_driver *driver;
 	struct zpool *zpool;

 	pr_debug("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);
 	zpool->ops = ops;

 	if (!zpool->pool) {
 		pr_err("couldn't create %s pool\n", type);
 		zpool_put_driver(driver);
 		kfree(zpool);
 		return NULL;
 	}

 	pr_debug("created pool type %s\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_debug("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);
 }

 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Dan Streetman <ddstreet@ieee.org>");
 MODULE_DESCRIPTION("Common API for compressed memory storage");
	/*
	* 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;
	const 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);

	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,
	const struct zpool_ops *ops)
	{
	struct zpool_driver *driver;
	struct zpool *zpool;

	pr_debug("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);
	zpool->ops = ops;

	if (!zpool->pool) {
	pr_err("couldn't create %s pool\n", type);
	zpool_put_driver(driver);
	kfree(zpool);
	return NULL;
	}

	pr_debug("created pool type %s\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_debug("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);
	}

	MODULE_LICENSE("GPL");
	MODULE_AUTHOR("Dan Streetman <ddstreet@ieee.org>");
	MODULE_DESCRIPTION("Common API for compressed memory storage");