1 /* 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. 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/>. 22 */ 23 24 #ifndef _SPL_SHRINKER_H 25 #define _SPL_SHRINKER_H 26 27 #include <linux/mm.h> 28 #include <linux/fs.h> 29 30 /* 31 * Due to frequent changes in the shrinker API the following 32 * compatibility wrapper should be used. 33 * 34 * shrinker = spl_register_shrinker(name, countfunc, scanfunc, seek_cost); 35 * spl_unregister_shrinker(shrinker); 36 * 37 * spl_register_shrinker is used to create and register a shrinker with the 38 * given name. 39 * The countfunc returns the number of free-able objects. 40 * The scanfunc returns the number of objects that were freed. 41 * The callbacks can return SHRINK_STOP if further calls can't make any more 42 * progress. Note that a return value of SHRINK_EMPTY is currently not 43 * supported. 44 * 45 * Example: 46 * 47 * static unsigned long 48 * my_count(struct shrinker *shrink, struct shrink_control *sc) 49 * { 50 * ...calculate number of objects in the cache... 51 * 52 * return (number of objects in the cache); 53 * } 54 * 55 * static unsigned long 56 * my_scan(struct shrinker *shrink, struct shrink_control *sc) 57 * { 58 * ...scan objects in the cache and reclaim them... 59 * } 60 * 61 * static struct shrinker *my_shrinker; 62 * 63 * void my_init_func(void) { 64 * my_shrinker = spl_register_shrinker("my-shrinker", 65 * my_count, my_scan, DEFAULT_SEEKS); 66 * } 67 * 68 * void my_fini_func(void) { 69 * spl_unregister_shrinker(my_shrinker); 70 * } 71 */ 72 73 typedef unsigned long (*spl_shrinker_cb) 74 (struct shrinker *, struct shrink_control *); 75 76 struct shrinker *spl_register_shrinker(const char *name, 77 spl_shrinker_cb countfunc, spl_shrinker_cb scanfunc, int seek_cost); 78 void spl_unregister_shrinker(struct shrinker *); 79 80 #ifndef SHRINK_STOP 81 /* 3.0-3.11 compatibility */ 82 #define SHRINK_STOP (-1) 83 #endif 84 85 #endif /* SPL_SHRINKER_H */ 86