Add ability to scrub from last scrubbed txg
[zfs.git] / include / os / linux / spl / sys / shrinker.h
blobbca4c850694a22f87955015af65ba5c496181aa3
1 /*
2 * Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
3 * Copyright (C) 2007 The Regents of the University of California.
4 * Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
5 * Written by Brian Behlendorf <behlendorf1@llnl.gov>.
6 * UCRL-CODE-235197
8 * This file is part of the SPL, Solaris Porting Layer.
10 * The SPL is free software; you can redistribute it and/or modify it
11 * under the terms of the GNU General Public License as published by the
12 * Free Software Foundation; either version 2 of the License, or (at your
13 * option) any later version.
15 * The SPL is distributed in the hope that it will be useful, but WITHOUT
16 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
17 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
18 * for more details.
20 * You should have received a copy of the GNU General Public License along
21 * with the SPL. If not, see <http://www.gnu.org/licenses/>.
24 #ifndef _SPL_SHRINKER_H
25 #define _SPL_SHRINKER_H
27 #include <linux/mm.h>
28 #include <linux/fs.h>
31 * Due to frequent changes in the shrinker API the following
32 * compatibility wrapper should be used.
34 * shrinker = spl_register_shrinker(name, countfunc, scanfunc, seek_cost);
35 * spl_unregister_shrinker(shrinker);
37 * spl_register_shrinker is used to create and register a shrinker with the
38 * given name.
39 * The countfunc returns the number of free-able objects.
40 * The scanfunc returns the number of objects that were freed.
41 * The callbacks can return SHRINK_STOP if further calls can't make any more
42 * progress. Note that a return value of SHRINK_EMPTY is currently not
43 * supported.
45 * Example:
47 * static unsigned long
48 * my_count(struct shrinker *shrink, struct shrink_control *sc)
49 * {
50 * ...calculate number of objects in the cache...
52 * return (number of objects in the cache);
53 * }
55 * static unsigned long
56 * my_scan(struct shrinker *shrink, struct shrink_control *sc)
57 * {
58 * ...scan objects in the cache and reclaim them...
59 * }
61 * static struct shrinker *my_shrinker;
63 * void my_init_func(void) {
64 * my_shrinker = spl_register_shrinker("my-shrinker",
65 * my_count, my_scan, DEFAULT_SEEKS);
66 * }
68 * void my_fini_func(void) {
69 * spl_unregister_shrinker(my_shrinker);
70 * }
73 typedef unsigned long (*spl_shrinker_cb)
74 (struct shrinker *, struct shrink_control *);
76 struct shrinker *spl_register_shrinker(const char *name,
77 spl_shrinker_cb countfunc, spl_shrinker_cb scanfunc, int seek_cost);
78 void spl_unregister_shrinker(struct shrinker *);
80 #ifndef SHRINK_STOP
81 /* 3.0-3.11 compatibility */
82 #define SHRINK_STOP (-1)
83 #endif
85 #endif /* SPL_SHRINKER_H */