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
7 *
8 *  This file is part of the SPL, Solaris Porting Layer.
9 *
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.
14 *
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.
19 *
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/>.
22 *
23 *  Solaris Porting Layer (SPL) Shrinker Implementation.
24 */
25
26#include <sys/kmem.h>
27#include <sys/shrinker.h>
28
29#ifdef HAVE_SINGLE_SHRINKER_CALLBACK
30/* 3.0-3.11: single shrink() callback, which we wrap to carry both functions */
31struct spl_shrinker_wrap {
32	struct shrinker shrinker;
33	spl_shrinker_cb countfunc;
34	spl_shrinker_cb scanfunc;
35};
36
37static int
38spl_shrinker_single_cb(struct shrinker *shrinker, struct shrink_control *sc)
39{
40	struct spl_shrinker_wrap *sw = (struct spl_shrinker_wrap *)shrinker;
41
42	if (sc->nr_to_scan != 0)
43		(void) sw->scanfunc(&sw->shrinker, sc);
44	return (sw->countfunc(&sw->shrinker, sc));
45}
46#endif
47
48struct shrinker *
49spl_register_shrinker(const char *name, spl_shrinker_cb countfunc,
50    spl_shrinker_cb scanfunc, int seek_cost)
51{
52	struct shrinker *shrinker;
53
54	/* allocate shrinker */
55#if defined(HAVE_SHRINKER_REGISTER)
56	/* 6.7: kernel will allocate the shrinker for us */
57	shrinker = shrinker_alloc(0, name);
58#elif defined(HAVE_SPLIT_SHRINKER_CALLBACK)
59	/* 3.12-6.6: we allocate the shrinker  */
60	shrinker = kmem_zalloc(sizeof (struct shrinker), KM_SLEEP);
61#elif defined(HAVE_SINGLE_SHRINKER_CALLBACK)
62	/* 3.0-3.11: allocate a wrapper */
63	struct spl_shrinker_wrap *sw =
64	    kmem_zalloc(sizeof (struct spl_shrinker_wrap), KM_SLEEP);
65	shrinker = &sw->shrinker;
66#else
67	/* 2.x-2.6.22, or a newer shrinker API has been introduced. */
68#error "Unknown shrinker API"
69#endif
70
71	if (shrinker == NULL)
72		return (NULL);
73
74	/* set callbacks */
75#ifdef HAVE_SINGLE_SHRINKER_CALLBACK
76	sw->countfunc = countfunc;
77	sw->scanfunc = scanfunc;
78	shrinker->shrink = spl_shrinker_single_cb;
79#else
80	shrinker->count_objects = countfunc;
81	shrinker->scan_objects = scanfunc;
82#endif
83
84	/* set params */
85	shrinker->seeks = seek_cost;
86
87	/* register with kernel */
88#if defined(HAVE_SHRINKER_REGISTER)
89	shrinker_register(shrinker);
90#elif defined(HAVE_REGISTER_SHRINKER_VARARG)
91	register_shrinker(shrinker, name);
92#else
93	register_shrinker(shrinker);
94#endif
95
96	return (shrinker);
97}
98EXPORT_SYMBOL(spl_register_shrinker);
99
100void
101spl_unregister_shrinker(struct shrinker *shrinker)
102{
103#if defined(HAVE_SHRINKER_REGISTER)
104	shrinker_free(shrinker);
105#elif defined(HAVE_SPLIT_SHRINKER_CALLBACK)
106	unregister_shrinker(shrinker);
107	kmem_free(shrinker, sizeof (struct shrinker));
108#elif defined(HAVE_SINGLE_SHRINKER_CALLBACK)
109	unregister_shrinker(shrinker);
110	kmem_free(shrinker, sizeof (struct spl_shrinker_wrap));
111#else
112#error "Unknown shrinker API"
113#endif
114}
115EXPORT_SYMBOL(spl_unregister_shrinker);
116