--- /dev/null
+/*
+ * 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
--- /dev/null
+/*
+ * 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");
projects / deliverable / linux.git / commitdiff
