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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * 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 {
     struct zpool_driver *driver;
     void *pool;
     const struct zpool_ops *ops;
     bool evictable;
     bool can_sleep_mapped;
 };
 
 static LIST_HEAD(drivers_head);
 static DEFINE_SPINLOCK(drivers_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);
 
 /* this assumes @type is null-terminated. */
 static struct zpool_driver *zpool_get_driver(const 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_has_pool() - Check if the pool driver is available
  * @type:   The type of the zpool to check (e.g. zbud, zsmalloc)
  *
  * This checks if the @type pool driver is available.  This will try to load
  * the requested module, if needed, but there is no guarantee the module will
  * still be loaded and available immediately after calling.  If this returns
  * true, the caller should assume the pool is available, but must be prepared
  * to handle the @zpool_create_pool() returning failure.  However if this
  * returns false, the caller should assume the requested pool type is not
  * available; either the requested pool type module does not exist, or could
  * not be loaded, and calling @zpool_create_pool() with the pool type will
  * fail.
  *
  * The @type string must be null-terminated.
  *
  * Returns: true if @type pool is available, false if not
  */
 bool zpool_has_pool(char *type)
 {
     struct zpool_driver *driver = zpool_get_driver(type);
 
     if (!driver) {
         request_module("zpool-%s", type);
         driver = zpool_get_driver(type);
     }
 
     if (!driver)
         return false;
 
     zpool_put_driver(driver);
     return true;
 }
 EXPORT_SYMBOL(zpool_has_pool);
 
 /**
  * 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 evictable.
  *
  * Implementations must guarantee this to be thread-safe.
  *
  * The @type and @name strings must be null-terminated.
  *
  * Returns: New zpool on success, NULL on failure.
  */
 struct zpool *zpool_create_pool(const char *type, const 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->driver = driver;
     zpool->pool = driver->create(name, gfp, ops, zpool);
     zpool->ops = ops;
     zpool->evictable = driver->shrink && ops && ops->evict;
     zpool->can_sleep_mapped = driver->sleep_mapped;
 
     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);
 
     return zpool;
 }
 
 /**
  * zpool_destroy_pool() - Destroy a zpool
  * @zpool:  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->driver->type);
 
     zpool->driver->destroy(zpool->pool);
     zpool_put_driver(zpool->driver);
     kfree(zpool);
 }
 
 /**
  * zpool_get_type() - Get the type of the zpool
  * @zpool:  The zpool to check
  *
  * This returns the type of the pool.
  *
  * Implementations must guarantee this to be thread-safe.
  *
  * Returns: The type of zpool.
  */
 const char *zpool_get_type(struct zpool *zpool)
 {
     return zpool->driver->type;
 }
 
 /**
  * zpool_malloc_support_movable() - Check if the zpool supports
  *  allocating movable memory
  * @zpool:  The zpool to check
  *
  * This returns if the zpool supports allocating movable memory.
  *
  * Implementations must guarantee this to be thread-safe.
  *
  * Returns: true if the zpool supports allocating movable memory, false if not
  */
 bool zpool_malloc_support_movable(struct zpool *zpool)
 {
     return zpool->driver->malloc_support_movable;
 }
 
 /**
  * zpool_malloc() - Allocate memory
  * @zpool:  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
  * @zpool:  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
  * @zpool:  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->driver->shrink(zpool->pool, pages, reclaimed) : -EINVAL;
 }
 
 /**
  * zpool_map_handle() - Map a previously allocated handle into memory
  * @zpool:  The zpool that the handle was allocated from
  * @handle: The handle to map
  * @mapmode:    How the memory should be mapped
  *
  * This maps a previously allocated handle into memory.  The @mapmode
  * 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 operations 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
  * @zpool:  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
  * @zpool:  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);
 }
 
 /**
  * zpool_evictable() - Test if zpool is potentially evictable
  * @zpool:  The zpool to test
  *
  * Zpool is only potentially evictable when it's created with struct
  * zpool_ops.evict and its driver implements struct zpool_driver.shrink.
  *
  * However, it doesn't necessarily mean driver will use zpool_ops.evict
  * in its implementation of zpool_driver.shrink. It could do internal
  * defragmentation instead.
  *
  * Returns: true if potentially evictable; false otherwise.
  */
 bool zpool_evictable(struct zpool *zpool)
 {
     return zpool->evictable;
 }
 
 /**
  * zpool_can_sleep_mapped - Test if zpool can sleep when do mapped.
  * @zpool:  The zpool to test
  *
  * Returns: true if zpool can sleep; false otherwise.
  */
 bool zpool_can_sleep_mapped(struct zpool *zpool)
 {
     return zpool->can_sleep_mapped;
 }
 
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Dan Streetman <ddstreet@ieee.org>");
 MODULE_DESCRIPTION("Common API for compressed memory storage");

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