mirror_zfs/include/spl/sys/shrinker.h
Brian Behlendorf a91258913f Prepare SPL repo to merge with ZFS repo
This commit removes everything from the repository except the core
SPL implementation for Linux.  Those files which remain have been
moved to non-conflicting locations to facilitate the merge.
The README.md and associated files have been updated accordingly.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
2018-05-29 14:51:39 -07:00

210 lines
6.2 KiB
C

/*
* 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 */