1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC. 4 * Copyright (C) 2007 The Regents of the University of California. 5 * Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER). 6 * Written by Brian Behlendorf <behlendorf1@llnl.gov>. 7 * UCRL-CODE-235197 8 * 9 * This file is part of the SPL, Solaris Porting Layer. 10 * 11 * The SPL is free software; you can redistribute it and/or modify it 12 * under the terms of the GNU General Public License as published by the 13 * Free Software Foundation; either version 2 of the License, or (at your 14 * option) any later version. 15 * 16 * The SPL is distributed in the hope that it will be useful, but WITHOUT 17 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 18 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 19 * for more details. 20 * 21 * You should have received a copy of the GNU General Public License along 22 * with the SPL. If not, see <http://www.gnu.org/licenses/>. 23 */ 24 25 #ifndef _SPL_SHRINKER_H 26 #define _SPL_SHRINKER_H 27 28 #include <linux/mm.h> 29 #include <linux/fs.h> 30 31 /* 32 * Due to frequent changes in the shrinker API the following 33 * compatibility wrapper should be used. 34 * 35 * shrinker = spl_register_shrinker(name, countfunc, scanfunc, seek_cost); 36 * spl_unregister_shrinker(shrinker); 37 * 38 * spl_register_shrinker is used to create and register a shrinker with the 39 * given name. 40 * The countfunc returns the number of free-able objects. 41 * The scanfunc returns the number of objects that were freed. 42 * The callbacks can return SHRINK_STOP if further calls can't make any more 43 * progress. Note that a return value of SHRINK_EMPTY is currently not 44 * supported. 45 * 46 * Example: 47 * 48 * static unsigned long 49 * my_count(struct shrinker *shrink, struct shrink_control *sc) 50 * { 51 * ...calculate number of objects in the cache... 52 * 53 * return (number of objects in the cache); 54 * } 55 * 56 * static unsigned long 57 * my_scan(struct shrinker *shrink, struct shrink_control *sc) 58 * { 59 * ...scan objects in the cache and reclaim them... 60 * } 61 * 62 * static struct shrinker *my_shrinker; 63 * 64 * void my_init_func(void) { 65 * my_shrinker = spl_register_shrinker("my-shrinker", 66 * my_count, my_scan, DEFAULT_SEEKS); 67 * } 68 * 69 * void my_fini_func(void) { 70 * spl_unregister_shrinker(my_shrinker); 71 * } 72 */ 73 74 typedef unsigned long (*spl_shrinker_cb) 75 (struct shrinker *, struct shrink_control *); 76 77 struct shrinker *spl_register_shrinker(const char *name, 78 spl_shrinker_cb countfunc, spl_shrinker_cb scanfunc, int seek_cost); 79 void spl_unregister_shrinker(struct shrinker *); 80 81 #ifndef SHRINK_STOP 82 /* 3.0-3.11 compatibility */ 83 #define SHRINK_STOP (-1) 84 #endif 85 86 #endif /* SPL_SHRINKER_H */ 87