mirror_zfs/include/os/linux/spl/sys/shrinker.h
Brian Behlendorf 67b1362f04 Style fixes
* Fix cstyle issue in shrinker.h which exceeded 80 columns.
* Silence shellcheck warning in zpool.d/smart script.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
2020-06-27 17:38:55 -07:00

111 lines
3.4 KiB
C

/*
* 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.
* For details, see <http://zfsonlinux.org/>.
*
* 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);
* }
*/
#define spl_register_shrinker(x) register_shrinker(x)
#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 */