/* * 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 . * UCRL-CODE-235197 * * This file is part of the SPL, Solaris Porting Layer. * For details, see . * * 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 . */ #ifndef _SPL_SHRINKER_H #define _SPL_SHRINKER_H #include #include #if !defined(HAVE_SHRINK_CONTROL_STRUCT) struct shrink_control { gfp_t gfp_mask; unsigned long nr_to_scan; }; #endif /* HAVE_SHRINK_CONTROL_STRUCT */ /* * Due to frequent changes in the shrinker API the following * compatibility wrappers should be used. They are as follows: * * SPL_SHRINKER_DECLARE is used to declare the shrinker which is * passed to spl_register_shrinker()/spl_unregister_shrinker(). Use * shrinker_name to set the shrinker variable name, shrinker_callback * to set the callback function, and seek_cost to define the cost of * reclaiming an object. * * SPL_SHRINKER_DECLARE(shrinker_name, shrinker_callback, seek_cost); * * SPL_SHRINKER_CALLBACK_FWD_DECLARE is used when a forward declaration * of the shrinker callback function is required. Only the callback * function needs to be passed. * * SPL_SHRINKER_CALLBACK_FWD_DECLARE(shrinker_callback); * * SPL_SHRINKER_CALLBACK_WRAPPER is used to declare the callback function * which is registered with the shrinker. This function will call your * custom shrinker which must use the following prototype. Notice the * leading __'s, these must be appended to the callback_function name. * * int __shrinker_callback(struct shrinker *, struct shrink_control *) * SPL_SHRINKER_CALLBACK_WRAPPER(shrinker_callback);a * * * Example: * * SPL_SHRINKER_CALLBACK_FWD_DECLARE(my_shrinker_fn); * SPL_SHRINKER_DECLARE(my_shrinker, my_shrinker_fn, 1); * * static int * __my_shrinker_fn(struct shrinker *shrink, struct shrink_control *sc) * { * if (sc->nr_to_scan) { * ...scan objects in the cache and reclaim them... * } * * ...calculate number of objects in the cache... * * return (number of objects in the cache); * } * SPL_SHRINKER_CALLBACK_WRAPPER(my_shrinker_fn); */ #define spl_register_shrinker(x) register_shrinker(x) #define spl_unregister_shrinker(x) unregister_shrinker(x) /* * Linux 2.6.23 - 2.6.34 Shrinker API Compatibility. */ #if defined(HAVE_2ARGS_OLD_SHRINKER_CALLBACK) #define SPL_SHRINKER_DECLARE(s, x, y) \ static struct shrinker s = { \ .shrink = x, \ .seeks = y \ } #define SPL_SHRINKER_CALLBACK_FWD_DECLARE(fn) \ static int fn(int nr_to_scan, unsigned int gfp_mask) #define SPL_SHRINKER_CALLBACK_WRAPPER(fn) \ static int \ fn(int nr_to_scan, unsigned int gfp_mask) \ { \ struct shrink_control sc; \ \ sc.nr_to_scan = nr_to_scan; \ sc.gfp_mask = gfp_mask; \ \ return (__ ## fn(NULL, &sc)); \ } /* * Linux 2.6.35 to 2.6.39 Shrinker API Compatibility. */ #elif defined(HAVE_3ARGS_SHRINKER_CALLBACK) #define SPL_SHRINKER_DECLARE(s, x, y) \ static struct shrinker s = { \ .shrink = x, \ .seeks = y \ } #define SPL_SHRINKER_CALLBACK_FWD_DECLARE(fn) \ static int fn(struct shrinker *, int, unsigned int) #define SPL_SHRINKER_CALLBACK_WRAPPER(fn) \ static int \ fn(struct shrinker *shrink, int nr_to_scan, unsigned int gfp_mask) \ { \ struct shrink_control sc; \ \ sc.nr_to_scan = nr_to_scan; \ sc.gfp_mask = gfp_mask; \ \ return (__ ## fn(shrink, &sc)); \ } /* * Linux 3.0 to 3.11 Shrinker API Compatibility. */ #elif defined(HAVE_2ARGS_NEW_SHRINKER_CALLBACK) #define SPL_SHRINKER_DECLARE(s, x, y) \ static struct shrinker s = { \ .shrink = x, \ .seeks = y \ } #define SPL_SHRINKER_CALLBACK_FWD_DECLARE(fn) \ static int fn(struct shrinker *, struct shrink_control *) #define SPL_SHRINKER_CALLBACK_WRAPPER(fn) \ static int \ fn(struct shrinker *shrink, struct shrink_control *sc) \ { \ return (__ ## fn(shrink, sc)); \ } /* * Linux 3.12 and later Shrinker API Compatibility. */ #elif defined(HAVE_SPLIT_SHRINKER_CALLBACK) #define SPL_SHRINKER_DECLARE(s, x, y) \ static struct shrinker s = { \ .count_objects = x ## _count_objects, \ .scan_objects = x ## _scan_objects, \ .seeks = y \ } #define SPL_SHRINKER_CALLBACK_FWD_DECLARE(fn) \ static unsigned long fn ## _count_objects(struct shrinker *, \ struct shrink_control *); \ static unsigned long fn ## _scan_objects(struct shrinker *, \ struct shrink_control *) #define SPL_SHRINKER_CALLBACK_WRAPPER(fn) \ static unsigned long \ fn ## _count_objects(struct shrinker *shrink, struct shrink_control *sc)\ { \ int __ret__; \ \ sc->nr_to_scan = 0; \ __ret__ = __ ## fn(NULL, sc); \ \ /* Errors may not be returned and must be converted to zeros */ \ return ((__ret__ < 0) ? 0 : __ret__); \ } \ \ static unsigned long \ fn ## _scan_objects(struct shrinker *shrink, struct shrink_control *sc) \ { \ int __ret__; \ \ __ret__ = __ ## fn(NULL, sc); \ return ((__ret__ < 0) ? SHRINK_STOP : __ret__); \ } #else /* * Linux 2.x to 2.6.22, or a newer shrinker API has been introduced. */ #error "Unknown shrinker callback" #endif #if defined(HAVE_SPLIT_SHRINKER_CALLBACK) typedef unsigned long spl_shrinker_t; #else typedef int spl_shrinker_t; #define SHRINK_STOP (-1) #endif #endif /* SPL_SHRINKER_H */