zfs/include/spl/sys/shrinker.h - backupdr - Git at Google

 /*
  *  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 */
	/*
	* 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 */