210 lines
6.2 KiB
C
210 lines
6.2 KiB
C
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/*
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* Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
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* Copyright (C) 2007 The Regents of the University of California.
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* Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
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* Written by Brian Behlendorf <behlendorf1@llnl.gov>.
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* UCRL-CODE-235197
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*
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* This file is part of the SPL, Solaris Porting Layer.
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* For details, see <http://zfsonlinux.org/>.
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*
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* The SPL is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version.
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*
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* The SPL is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with the SPL. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef _SPL_SHRINKER_H
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#define _SPL_SHRINKER_H
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#include <linux/mm.h>
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#include <linux/fs.h>
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#if !defined(HAVE_SHRINK_CONTROL_STRUCT)
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struct shrink_control {
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gfp_t gfp_mask;
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unsigned long nr_to_scan;
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};
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#endif /* HAVE_SHRINK_CONTROL_STRUCT */
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/*
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* Due to frequent changes in the shrinker API the following
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* compatibility wrappers should be used. They are as follows:
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*
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* SPL_SHRINKER_DECLARE is used to declare the shrinker which is
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* passed to spl_register_shrinker()/spl_unregister_shrinker(). Use
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* shrinker_name to set the shrinker variable name, shrinker_callback
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* to set the callback function, and seek_cost to define the cost of
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* reclaiming an object.
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*
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* SPL_SHRINKER_DECLARE(shrinker_name, shrinker_callback, seek_cost);
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*
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* SPL_SHRINKER_CALLBACK_FWD_DECLARE is used when a forward declaration
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* of the shrinker callback function is required. Only the callback
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* function needs to be passed.
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*
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* SPL_SHRINKER_CALLBACK_FWD_DECLARE(shrinker_callback);
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*
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* SPL_SHRINKER_CALLBACK_WRAPPER is used to declare the callback function
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* which is registered with the shrinker. This function will call your
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* custom shrinker which must use the following prototype. Notice the
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* leading __'s, these must be appended to the callback_function name.
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*
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* int __shrinker_callback(struct shrinker *, struct shrink_control *)
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* SPL_SHRINKER_CALLBACK_WRAPPER(shrinker_callback);a
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*
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*
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* Example:
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*
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* SPL_SHRINKER_CALLBACK_FWD_DECLARE(my_shrinker_fn);
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* SPL_SHRINKER_DECLARE(my_shrinker, my_shrinker_fn, 1);
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*
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* static int
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* __my_shrinker_fn(struct shrinker *shrink, struct shrink_control *sc)
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* {
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* if (sc->nr_to_scan) {
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* ...scan objects in the cache and reclaim them...
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* }
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*
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* ...calculate number of objects in the cache...
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*
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* return (number of objects in the cache);
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* }
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* SPL_SHRINKER_CALLBACK_WRAPPER(my_shrinker_fn);
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*/
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#define spl_register_shrinker(x) register_shrinker(x)
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#define spl_unregister_shrinker(x) unregister_shrinker(x)
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/*
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* Linux 2.6.23 - 2.6.34 Shrinker API Compatibility.
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*/
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#if defined(HAVE_2ARGS_OLD_SHRINKER_CALLBACK)
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#define SPL_SHRINKER_DECLARE(s, x, y) \
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static struct shrinker s = { \
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.shrink = x, \
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.seeks = y \
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}
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#define SPL_SHRINKER_CALLBACK_FWD_DECLARE(fn) \
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static int fn(int nr_to_scan, unsigned int gfp_mask)
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#define SPL_SHRINKER_CALLBACK_WRAPPER(fn) \
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static int \
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fn(int nr_to_scan, unsigned int gfp_mask) \
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{ \
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struct shrink_control sc; \
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\
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sc.nr_to_scan = nr_to_scan; \
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sc.gfp_mask = gfp_mask; \
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\
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return (__ ## fn(NULL, &sc)); \
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}
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/*
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* Linux 2.6.35 to 2.6.39 Shrinker API Compatibility.
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*/
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#elif defined(HAVE_3ARGS_SHRINKER_CALLBACK)
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#define SPL_SHRINKER_DECLARE(s, x, y) \
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static struct shrinker s = { \
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.shrink = x, \
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.seeks = y \
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}
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#define SPL_SHRINKER_CALLBACK_FWD_DECLARE(fn) \
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static int fn(struct shrinker *, int, unsigned int)
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#define SPL_SHRINKER_CALLBACK_WRAPPER(fn) \
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static int \
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fn(struct shrinker *shrink, int nr_to_scan, unsigned int gfp_mask) \
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{ \
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struct shrink_control sc; \
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\
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sc.nr_to_scan = nr_to_scan; \
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sc.gfp_mask = gfp_mask; \
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\
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return (__ ## fn(shrink, &sc)); \
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}
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/*
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* Linux 3.0 to 3.11 Shrinker API Compatibility.
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*/
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#elif defined(HAVE_2ARGS_NEW_SHRINKER_CALLBACK)
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#define SPL_SHRINKER_DECLARE(s, x, y) \
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static struct shrinker s = { \
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.shrink = x, \
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.seeks = y \
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}
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#define SPL_SHRINKER_CALLBACK_FWD_DECLARE(fn) \
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static int fn(struct shrinker *, struct shrink_control *)
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#define SPL_SHRINKER_CALLBACK_WRAPPER(fn) \
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static int \
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fn(struct shrinker *shrink, struct shrink_control *sc) \
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{ \
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return (__ ## fn(shrink, sc)); \
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}
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/*
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* Linux 3.12 and later Shrinker API Compatibility.
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*/
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#elif defined(HAVE_SPLIT_SHRINKER_CALLBACK)
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#define SPL_SHRINKER_DECLARE(s, x, y) \
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static struct shrinker s = { \
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.count_objects = x ## _count_objects, \
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.scan_objects = x ## _scan_objects, \
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.seeks = y \
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}
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#define SPL_SHRINKER_CALLBACK_FWD_DECLARE(fn) \
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static unsigned long fn ## _count_objects(struct shrinker *, \
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struct shrink_control *); \
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static unsigned long fn ## _scan_objects(struct shrinker *, \
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struct shrink_control *)
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#define SPL_SHRINKER_CALLBACK_WRAPPER(fn) \
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static unsigned long \
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fn ## _count_objects(struct shrinker *shrink, struct shrink_control *sc)\
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{ \
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int __ret__; \
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\
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sc->nr_to_scan = 0; \
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__ret__ = __ ## fn(NULL, sc); \
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\
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/* Errors may not be returned and must be converted to zeros */ \
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return ((__ret__ < 0) ? 0 : __ret__); \
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} \
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\
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static unsigned long \
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fn ## _scan_objects(struct shrinker *shrink, struct shrink_control *sc) \
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{ \
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int __ret__; \
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\
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__ret__ = __ ## fn(NULL, sc); \
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return ((__ret__ < 0) ? SHRINK_STOP : __ret__); \
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}
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#else
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/*
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* Linux 2.x to 2.6.22, or a newer shrinker API has been introduced.
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*/
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#error "Unknown shrinker callback"
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#endif
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#if defined(HAVE_SPLIT_SHRINKER_CALLBACK)
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typedef unsigned long spl_shrinker_t;
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#else
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typedef int spl_shrinker_t;
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#define SHRINK_STOP (-1)
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#endif
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#endif /* SPL_SHRINKER_H */
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