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/*
* 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>
#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 */
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