[mirror_zfs.git] / include / os / linux / spl / sys / shrinker.h

/*
 *  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 wrappers should be used.  They are as follows:
 *
 *   SPL_SHRINKER_DECLARE(varname, countfunc, scanfunc, seek_cost);
 *
 * SPL_SHRINKER_DECLARE is used to declare a shrinker with the name varname,
 * which is passed to spl_register_shrinker()/spl_unregister_shrinker().
 * 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...
 * }
 *
 * SPL_SHRINKER_DECLARE(my_shrinker, my_count, my_scan, DEFAULT_SEEKS);
 *
 * void my_init_func(void) {
 *	spl_register_shrinker(&my_shrinker);
 * }
 */

#ifdef HAVE_REGISTER_SHRINKER_VARARG
#define	spl_register_shrinker(x)	register_shrinker(x, "zfs-arc-shrinker")
#else
#define	spl_register_shrinker(x)	register_shrinker(x)
#endif
#define	spl_unregister_shrinker(x)	unregister_shrinker(x)

/*
 * Linux 3.0 to 3.11 Shrinker API Compatibility.
 */
#if defined(HAVE_SINGLE_SHRINKER_CALLBACK)
#define	SPL_SHRINKER_DECLARE(varname, countfunc, scanfunc, seek_cost)	\
static int								\
__ ## varname ## _wrapper(struct shrinker *shrink, struct shrink_control *sc)\
{									\
	if (sc->nr_to_scan != 0) {					\
		(void) scanfunc(shrink, sc);				\
	}								\
	return (countfunc(shrink, sc));					\
}									\
									\
static struct shrinker varname = {					\
	.shrink = __ ## varname ## _wrapper,				\
	.seeks = seek_cost,						\
}

#define	SHRINK_STOP	(-1)

/*
 * Linux 3.12 and later Shrinker API Compatibility.
 */
#elif defined(HAVE_SPLIT_SHRINKER_CALLBACK)
#define	SPL_SHRINKER_DECLARE(varname, countfunc, scanfunc, seek_cost)	\
static struct shrinker varname = {					\
	.count_objects = countfunc,					\
	.scan_objects = scanfunc,					\
	.seeks = seek_cost,						\
}

#else
/*
 * Linux 2.x to 2.6.22, or a newer shrinker API has been introduced.
 */
#error "Unknown shrinker callback"
#endif

#endif /* SPL_SHRINKER_H */
Commit	Line	Data
4b393c50	1	/*
716154c5 BB	2	* Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
	3	* Copyright (C) 2007 The Regents of the University of California.
	4	* Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
	5	* Written by Brian Behlendorf <behlendorf1@llnl.gov>.
	6	* UCRL-CODE-235197
	7	*
	8	* This file is part of the SPL, Solaris Porting Layer.
716154c5 BB	9	*
	10	* The SPL is free software; you can redistribute it and/or modify it
	11	* under the terms of the GNU General Public License as published by the
	12	* Free Software Foundation; either version 2 of the License, or (at your
	13	* option) any later version.
	14	*
	15	* The SPL is distributed in the hope that it will be useful, but WITHOUT
	16	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	17	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	18	* for more details.
	19	*
	20	* You should have received a copy of the GNU General Public License along
	21	* with the SPL. If not, see <http://www.gnu.org/licenses/>.
4b393c50	22	*/
716154c5	23
a9125891 BB	24	#ifndef _SPL_SHRINKER_H
a9125891 BB	25	#define _SPL_SHRINKER_H
baf2979e BB	26
baf2979e BB	27	#include <linux/mm.h>
914b0631	28	#include <linux/fs.h>
baf2979e	29
a55bcaad	30	/*
c3d9c0df RY	31	* Due to frequent changes in the shrinker API the following
	32	* compatibility wrappers should be used. They are as follows:
	33	*
270ece24	34	* SPL_SHRINKER_DECLARE(varname, countfunc, scanfunc, seek_cost);
c3d9c0df	35	*
270ece24 MA	36	* SPL_SHRINKER_DECLARE is used to declare a shrinker with the name varname,
	37	* which is passed to spl_register_shrinker()/spl_unregister_shrinker().
	38	* The countfunc returns the number of free-able objects.
	39	* The scanfunc returns the number of objects that were freed.
	40	* The callbacks can return SHRINK_STOP if further calls can't make any more
	41	* progress. Note that a return value of SHRINK_EMPTY is currently not
	42	* supported.
c3d9c0df RY	43	*
	44	* Example:
	45	*
270ece24 MA	46	* static unsigned long
270ece24 MA	47	* my_count(struct shrinker shrink, struct shrink_control sc)
c3d9c0df	48	* {
c3d9c0df RY	49	* ...calculate number of objects in the cache...
	50	*
	51	* return (number of objects in the cache);
	52	* }
270ece24 MA	53	*
	54	* static unsigned long
	55	* my_scan(struct shrinker shrink, struct shrink_control sc)
	56	* {
	57	* ...scan objects in the cache and reclaim them...
	58	* }
	59	*
	60	* SPL_SHRINKER_DECLARE(my_shrinker, my_count, my_scan, DEFAULT_SEEKS);
	61	*
	62	* void my_init_func(void) {
	63	* spl_register_shrinker(&my_shrinker);
	64	* }
a55bcaad	65	*/
495bd532	66
ad096763 CK	67	#ifdef HAVE_REGISTER_SHRINKER_VARARG
	68	#define spl_register_shrinker(x) register_shrinker(x, "zfs-arc-shrinker")
	69	#else
c3d9c0df	70	#define spl_register_shrinker(x) register_shrinker(x)
ad096763	71	#endif
c3d9c0df	72	#define spl_unregister_shrinker(x) unregister_shrinker(x)
495bd532	73
a55bcaad	74	/*
c3d9c0df	75	* Linux 3.0 to 3.11 Shrinker API Compatibility.
a55bcaad	76	*/
066e8252	77	#if defined(HAVE_SINGLE_SHRINKER_CALLBACK)
270ece24	78	#define SPL_SHRINKER_DECLARE(varname, countfunc, scanfunc, seek_cost) \
c3d9c0df	79	static int \
270ece24	80	__ ## varname ## _wrapper(struct shrinker shrink, struct shrink_control sc)\
c3d9c0df	81	{ \
270ece24 MA	82	if (sc->nr_to_scan != 0) { \
	83	(void) scanfunc(shrink, sc); \
	84	} \
	85	return (countfunc(shrink, sc)); \
	86	} \
	87	\
	88	static struct shrinker varname = { \
	89	.shrink = __ ## varname ## _wrapper, \
3442c2a0	90	.seeks = seek_cost, \
a55bcaad BB	91	}
a55bcaad BB	92
270ece24 MA	93	#define SHRINK_STOP (-1)
270ece24 MA	94
a55bcaad	95	/*
c3d9c0df	96	* Linux 3.12 and later Shrinker API Compatibility.
a55bcaad	97	*/
c3d9c0df	98	#elif defined(HAVE_SPLIT_SHRINKER_CALLBACK)
270ece24 MA	99	#define SPL_SHRINKER_DECLARE(varname, countfunc, scanfunc, seek_cost) \
	100	static struct shrinker varname = { \
	101	.count_objects = countfunc, \
	102	.scan_objects = scanfunc, \
3442c2a0	103	.seeks = seek_cost, \
a55bcaad BB	104	}
a55bcaad BB	105
c3d9c0df RY	106	#else
	107	/*
	108	* Linux 2.x to 2.6.22, or a newer shrinker API has been introduced.
	109	*/
	110	#error "Unknown shrinker callback"
	111	#endif
495bd532	112
a9125891	113	#endif /* SPL_SHRINKER_H */