110 lines
3.3 KiB
C
110 lines
3.3 KiB
C
/*
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* Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
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* Copyright (C) 2007 The Regents of the University of California.
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* Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
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* Written by Brian Behlendorf <behlendorf1@llnl.gov>.
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* UCRL-CODE-235197
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*
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* This file is part of the SPL, Solaris Porting Layer.
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*
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* The SPL is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version.
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*
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* The SPL is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with the SPL. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef _SPL_SHRINKER_H
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#define _SPL_SHRINKER_H
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#include <linux/mm.h>
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#include <linux/fs.h>
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/*
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* Due to frequent changes in the shrinker API the following
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* compatibility wrappers should be used. They are as follows:
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*
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* SPL_SHRINKER_DECLARE(varname, countfunc, scanfunc, seek_cost);
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*
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* SPL_SHRINKER_DECLARE is used to declare a shrinker with the name varname,
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* which is passed to spl_register_shrinker()/spl_unregister_shrinker().
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* The countfunc returns the number of free-able objects.
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* The scanfunc returns the number of objects that were freed.
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* The callbacks can return SHRINK_STOP if further calls can't make any more
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* progress. Note that a return value of SHRINK_EMPTY is currently not
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* supported.
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*
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* Example:
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*
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* static unsigned long
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* my_count(struct shrinker *shrink, struct shrink_control *sc)
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* {
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* ...calculate number of objects in the cache...
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*
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* return (number of objects in the cache);
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* }
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*
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* static unsigned long
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* my_scan(struct shrinker *shrink, struct shrink_control *sc)
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* {
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* ...scan objects in the cache and reclaim them...
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* }
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*
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* SPL_SHRINKER_DECLARE(my_shrinker, my_count, my_scan, DEFAULT_SEEKS);
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*
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* void my_init_func(void) {
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* spl_register_shrinker(&my_shrinker);
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* }
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*/
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#define spl_register_shrinker(x) register_shrinker(x)
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#define spl_unregister_shrinker(x) unregister_shrinker(x)
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/*
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* Linux 3.0 to 3.11 Shrinker API Compatibility.
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*/
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#if defined(HAVE_SINGLE_SHRINKER_CALLBACK)
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#define SPL_SHRINKER_DECLARE(varname, countfunc, scanfunc, seek_cost) \
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static int \
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__ ## varname ## _wrapper(struct shrinker *shrink, struct shrink_control *sc)\
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{ \
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if (sc->nr_to_scan != 0) { \
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(void) scanfunc(shrink, sc); \
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} \
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return (countfunc(shrink, sc)); \
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} \
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\
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static struct shrinker varname = { \
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.shrink = __ ## varname ## _wrapper, \
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.seeks = seek_cost, \
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}
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#define SHRINK_STOP (-1)
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/*
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* Linux 3.12 and later Shrinker API Compatibility.
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*/
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#elif defined(HAVE_SPLIT_SHRINKER_CALLBACK)
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#define SPL_SHRINKER_DECLARE(varname, countfunc, scanfunc, seek_cost) \
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static struct shrinker varname = { \
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.count_objects = countfunc, \
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.scan_objects = scanfunc, \
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.seeks = seek_cost, \
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}
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#else
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/*
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* Linux 2.x to 2.6.22, or a newer shrinker API has been introduced.
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*/
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#error "Unknown shrinker callback"
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#endif
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#endif /* SPL_SHRINKER_H */
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