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/*
* Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
* Copyright (C) 2007 The Regents of the University of California.
* Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
* Written by Brian Behlendorf <behlendorf1@llnl.gov>.
* UCRL-CODE-235197
*
* This file is part of the SPL, Solaris Porting Layer.
*
* The SPL is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*
* The SPL is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*
* You should have received a copy of the GNU General Public License along
* with the SPL. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef _SPL_SHRINKER_H
#define _SPL_SHRINKER_H
#include <linux/mm.h>
#include <linux/fs.h>
/*
* Due to frequent changes in the shrinker API the following
* compatibility wrapper should be used.
*
* shrinker = spl_register_shrinker(name, countfunc, scanfunc, seek_cost);
* spl_unregister_shrinker(shrinker);
*
* spl_register_shrinker is used to create and register a shrinker with the
* given name.
* The countfunc returns the number of free-able objects.
* The scanfunc returns the number of objects that were freed.
* The callbacks can return SHRINK_STOP if further calls can't make any more
* progress. Note that a return value of SHRINK_EMPTY is currently not
* supported.
*
* Example:
*
* static unsigned long
* my_count(struct shrinker *shrink, struct shrink_control *sc)
* {
* ...calculate number of objects in the cache...
*
* return (number of objects in the cache);
* }
*
* static unsigned long
* my_scan(struct shrinker *shrink, struct shrink_control *sc)
* {
* ...scan objects in the cache and reclaim them...
* }
*
* static struct shrinker *my_shrinker;
*
* void my_init_func(void) {
* my_shrinker = spl_register_shrinker("my-shrinker",
* my_count, my_scan, DEFAULT_SEEKS);
* }
*
* void my_fini_func(void) {
* spl_unregister_shrinker(my_shrinker);
* }
*/
typedef unsigned long (*spl_shrinker_cb)
(struct shrinker *, struct shrink_control *);
struct shrinker *spl_register_shrinker(const char *name,
spl_shrinker_cb countfunc, spl_shrinker_cb scanfunc, int seek_cost);
void spl_unregister_shrinker(struct shrinker *);
#ifndef SHRINK_STOP
/* 3.0-3.11 compatibility */
#define SHRINK_STOP (-1)
#endif
#endif /* SPL_SHRINKER_H */
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