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: Dan Streetman <ddstreet@ieee.org> Tested-by: Seth 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: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Dan Streetman
committed by
Linus Torvalds
Linus Torvalds
parent
99eef8e936
commit
af8d417a04
364
mm/zpool.c
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364
mm/zpool.c
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/*
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* zpool memory storage api
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*
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* Copyright (C) 2014 Dan Streetman
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*
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* This is a common frontend for memory storage pool implementations.
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* Typically, this is used to store compressed memory.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/list.h>
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#include <linux/types.h>
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/spinlock.h>
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#include <linux/module.h>
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#include <linux/zpool.h>
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struct zpool {
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char *type;
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struct zpool_driver *driver;
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void *pool;
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struct zpool_ops *ops;
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struct list_head list;
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};
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static LIST_HEAD(drivers_head);
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static DEFINE_SPINLOCK(drivers_lock);
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static LIST_HEAD(pools_head);
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static DEFINE_SPINLOCK(pools_lock);
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/**
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* zpool_register_driver() - register a zpool implementation.
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* @driver: driver to register
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*/
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void zpool_register_driver(struct zpool_driver *driver)
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{
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spin_lock(&drivers_lock);
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atomic_set(&driver->refcount, 0);
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list_add(&driver->list, &drivers_head);
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spin_unlock(&drivers_lock);
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}
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EXPORT_SYMBOL(zpool_register_driver);
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/**
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* zpool_unregister_driver() - unregister a zpool implementation.
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* @driver: driver to unregister.
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*
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* Module usage counting is used to prevent using a driver
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* while/after unloading, so if this is called from module
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* exit function, this should never fail; if called from
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* other than the module exit function, and this returns
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* failure, the driver is in use and must remain available.
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*/
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int zpool_unregister_driver(struct zpool_driver *driver)
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{
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int ret = 0, refcount;
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spin_lock(&drivers_lock);
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refcount = atomic_read(&driver->refcount);
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WARN_ON(refcount < 0);
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if (refcount > 0)
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ret = -EBUSY;
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else
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list_del(&driver->list);
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spin_unlock(&drivers_lock);
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return ret;
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}
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EXPORT_SYMBOL(zpool_unregister_driver);
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/**
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* zpool_evict() - evict callback from a zpool implementation.
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* @pool: pool to evict from.
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* @handle: handle to evict.
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*
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* This can be used by zpool implementations to call the
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* user's evict zpool_ops struct evict callback.
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*/
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int zpool_evict(void *pool, unsigned long handle)
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{
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struct zpool *zpool;
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spin_lock(&pools_lock);
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list_for_each_entry(zpool, &pools_head, list) {
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if (zpool->pool == pool) {
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spin_unlock(&pools_lock);
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if (!zpool->ops || !zpool->ops->evict)
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return -EINVAL;
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return zpool->ops->evict(zpool, handle);
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}
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}
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spin_unlock(&pools_lock);
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return -ENOENT;
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}
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EXPORT_SYMBOL(zpool_evict);
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static struct zpool_driver *zpool_get_driver(char *type)
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{
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struct zpool_driver *driver;
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spin_lock(&drivers_lock);
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list_for_each_entry(driver, &drivers_head, list) {
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if (!strcmp(driver->type, type)) {
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bool got = try_module_get(driver->owner);
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if (got)
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atomic_inc(&driver->refcount);
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spin_unlock(&drivers_lock);
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return got ? driver : NULL;
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}
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}
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spin_unlock(&drivers_lock);
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return NULL;
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}
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static void zpool_put_driver(struct zpool_driver *driver)
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{
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atomic_dec(&driver->refcount);
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module_put(driver->owner);
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}
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/**
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* zpool_create_pool() - Create a new zpool
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* @type The type of the zpool to create (e.g. zbud, zsmalloc)
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* @gfp The GFP flags to use when allocating the pool.
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* @ops The optional ops callback.
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*
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* This creates a new zpool of the specified type. The gfp flags will be
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* used when allocating memory, if the implementation supports it. If the
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* ops param is NULL, then the created zpool will not be shrinkable.
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*
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* Implementations must guarantee this to be thread-safe.
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*
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* Returns: New zpool on success, NULL on failure.
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*/
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struct zpool *zpool_create_pool(char *type, gfp_t gfp, struct zpool_ops *ops)
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{
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struct zpool_driver *driver;
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struct zpool *zpool;
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pr_info("creating pool type %s\n", type);
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driver = zpool_get_driver(type);
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if (!driver) {
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request_module(type);
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driver = zpool_get_driver(type);
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}
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if (!driver) {
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pr_err("no driver for type %s\n", type);
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return NULL;
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}
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zpool = kmalloc(sizeof(*zpool), gfp);
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if (!zpool) {
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pr_err("couldn't create zpool - out of memory\n");
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zpool_put_driver(driver);
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return NULL;
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}
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zpool->type = driver->type;
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zpool->driver = driver;
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zpool->pool = driver->create(gfp, ops);
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zpool->ops = ops;
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if (!zpool->pool) {
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pr_err("couldn't create %s pool\n", type);
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zpool_put_driver(driver);
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kfree(zpool);
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return NULL;
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}
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pr_info("created %s pool\n", type);
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spin_lock(&pools_lock);
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list_add(&zpool->list, &pools_head);
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spin_unlock(&pools_lock);
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return zpool;
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}
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/**
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* zpool_destroy_pool() - Destroy a zpool
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* @pool The zpool to destroy.
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*
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* Implementations must guarantee this to be thread-safe,
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* however only when destroying different pools. The same
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* pool should only be destroyed once, and should not be used
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* after it is destroyed.
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*
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* This destroys an existing zpool. The zpool should not be in use.
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*/
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void zpool_destroy_pool(struct zpool *zpool)
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{
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pr_info("destroying pool type %s\n", zpool->type);
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spin_lock(&pools_lock);
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list_del(&zpool->list);
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spin_unlock(&pools_lock);
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zpool->driver->destroy(zpool->pool);
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zpool_put_driver(zpool->driver);
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kfree(zpool);
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}
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/**
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* zpool_get_type() - Get the type of the zpool
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* @pool The zpool to check
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*
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* This returns the type of the pool.
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*
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* Implementations must guarantee this to be thread-safe.
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*
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* Returns: The type of zpool.
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*/
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char *zpool_get_type(struct zpool *zpool)
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{
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return zpool->type;
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}
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/**
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* zpool_malloc() - Allocate memory
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* @pool The zpool to allocate from.
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* @size The amount of memory to allocate.
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* @gfp The GFP flags to use when allocating memory.
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* @handle Pointer to the handle to set
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*
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* This allocates the requested amount of memory from the pool.
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* The gfp flags will be used when allocating memory, if the
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* implementation supports it. The provided @handle will be
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* set to the allocated object handle.
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*
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* Implementations must guarantee this to be thread-safe.
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*
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* Returns: 0 on success, negative value on error.
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*/
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int zpool_malloc(struct zpool *zpool, size_t size, gfp_t gfp,
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unsigned long *handle)
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{
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return zpool->driver->malloc(zpool->pool, size, gfp, handle);
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}
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/**
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* zpool_free() - Free previously allocated memory
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* @pool The zpool that allocated the memory.
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* @handle The handle to the memory to free.
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*
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* This frees previously allocated memory. This does not guarantee
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* that the pool will actually free memory, only that the memory
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* in the pool will become available for use by the pool.
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*
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* Implementations must guarantee this to be thread-safe,
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* however only when freeing different handles. The same
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* handle should only be freed once, and should not be used
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* after freeing.
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*/
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void zpool_free(struct zpool *zpool, unsigned long handle)
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{
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zpool->driver->free(zpool->pool, handle);
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}
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/**
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* zpool_shrink() - Shrink the pool size
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* @pool The zpool to shrink.
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* @pages The number of pages to shrink the pool.
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* @reclaimed The number of pages successfully evicted.
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*
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* This attempts to shrink the actual memory size of the pool
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* by evicting currently used handle(s). If the pool was
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* created with no zpool_ops, or the evict call fails for any
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* of the handles, this will fail. If non-NULL, the @reclaimed
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* parameter will be set to the number of pages reclaimed,
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* which may be more than the number of pages requested.
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*
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* Implementations must guarantee this to be thread-safe.
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*
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* Returns: 0 on success, negative value on error/failure.
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*/
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int zpool_shrink(struct zpool *zpool, unsigned int pages,
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unsigned int *reclaimed)
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{
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return zpool->driver->shrink(zpool->pool, pages, reclaimed);
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}
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/**
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* zpool_map_handle() - Map a previously allocated handle into memory
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* @pool The zpool that the handle was allocated from
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* @handle The handle to map
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* @mm How the memory should be mapped
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*
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* This maps a previously allocated handle into memory. The @mm
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* param indicates to the implementation how the memory will be
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* used, i.e. read-only, write-only, read-write. If the
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* implementation does not support it, the memory will be treated
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* as read-write.
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*
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* This may hold locks, disable interrupts, and/or preemption,
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* and the zpool_unmap_handle() must be called to undo those
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* actions. The code that uses the mapped handle should complete
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* its operatons on the mapped handle memory quickly and unmap
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* as soon as possible. As the implementation may use per-cpu
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* data, multiple handles should not be mapped concurrently on
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* any cpu.
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*
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* Returns: A pointer to the handle's mapped memory area.
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*/
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void *zpool_map_handle(struct zpool *zpool, unsigned long handle,
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enum zpool_mapmode mapmode)
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{
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return zpool->driver->map(zpool->pool, handle, mapmode);
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}
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/**
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* zpool_unmap_handle() - Unmap a previously mapped handle
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* @pool The zpool that the handle was allocated from
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* @handle The handle to unmap
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*
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* This unmaps a previously mapped handle. Any locks or other
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* actions that the implementation took in zpool_map_handle()
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* will be undone here. The memory area returned from
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* zpool_map_handle() should no longer be used after this.
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*/
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void zpool_unmap_handle(struct zpool *zpool, unsigned long handle)
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{
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zpool->driver->unmap(zpool->pool, handle);
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}
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/**
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* zpool_get_total_size() - The total size of the pool
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* @pool The zpool to check
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*
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* This returns the total size in bytes of the pool.
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*
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* Returns: Total size of the zpool in bytes.
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*/
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u64 zpool_get_total_size(struct zpool *zpool)
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{
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return zpool->driver->total_size(zpool->pool);
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}
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static int __init init_zpool(void)
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{
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pr_info("loaded\n");
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return 0;
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}
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static void __exit exit_zpool(void)
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{
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pr_info("unloaded\n");
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}
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module_init(init_zpool);
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module_exit(exit_zpool);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Dan Streetman <ddstreet@ieee.org>");
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MODULE_DESCRIPTION("Common API for compressed memory storage");
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