default_pager.c revision 16409 
1/*
2 * Copyright (c) 1995, David Greenman
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by David Greenman.
16 * 4. The name of the author may not be used to endorse or promote products
17 *    derived from this software without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 *
31 *	$Id: default_pager.c,v 1.8 1996/05/29 05:12:23 dyson Exp $
32 */
33
34#include <sys/param.h>
35#include <sys/systm.h>
36#include <sys/kernel.h>
37#include <sys/malloc.h>
38#include <sys/queue.h>
39#include <sys/vmmeter.h>
40
41#include <vm/vm.h>
42#include <vm/vm_param.h>
43#include <vm/vm_prot.h>
44#include <vm/vm_object.h>
45#include <vm/vm_page.h>
46#include <vm/vm_pager.h>
47#include <vm/default_pager.h>
48#include <vm/swap_pager.h>
49
50static vm_object_t default_pager_alloc __P((void *, vm_size_t, vm_prot_t,
51		vm_ooffset_t));
52static void default_pager_dealloc __P((vm_object_t));
53static int default_pager_getpages __P((vm_object_t, vm_page_t *, int, int));
54static int default_pager_putpages __P((vm_object_t, vm_page_t *, int,
55		boolean_t, int *));
56static boolean_t default_pager_haspage __P((vm_object_t, vm_pindex_t, int *,
57		int *));
58/*
59 * pagerops for OBJT_DEFAULT - "default pager".
60 */
61struct pagerops defaultpagerops = {
62	NULL,
63	default_pager_alloc,
64	default_pager_dealloc,
65	default_pager_getpages,
66	default_pager_putpages,
67	default_pager_haspage,
68	NULL
69};
70
71/*
72 * no_pager_alloc just returns an initialized object.
73 */
74static vm_object_t
75default_pager_alloc(handle, size, prot, offset)
76	void *handle;
77	register vm_size_t size;
78	vm_prot_t prot;
79	vm_ooffset_t offset;
80{
81	if (handle != NULL)
82		panic("default_pager_alloc: handle specified");
83
84	return vm_object_allocate(OBJT_DEFAULT, OFF_TO_IDX(offset) + size);
85}
86
87static void
88default_pager_dealloc(object)
89	vm_object_t object;
90{
91	/*
92	 * OBJT_DEFAULT objects have no special resources allocated to them.
93	 */
94}
95
96/*
97 * The default pager has no backing store, so we always return
98 * failure.
99 */
100static int
101default_pager_getpages(object, m, count, reqpage)
102	vm_object_t object;
103	vm_page_t *m;
104	int count;
105	int reqpage;
106{
107	return VM_PAGER_FAIL;
108}
109
110static int
111default_pager_putpages(object, m, c, sync, rtvals)
112	vm_object_t object;
113	vm_page_t *m;
114	int c;
115	boolean_t sync;
116	int *rtvals;
117{
118	int i;
119
120	/*
121	 * Try to convert the object type into a OBJT_SWAP.
122	 * If the swp structure allocation fails, convert it
123	 * back to OBJT_DEFAULT and return failure. Otherwise
124	 * pass this putpages to the swap pager.
125	 */
126	object->type = OBJT_SWAP;
127
128	if (swap_pager_swp_alloc(object, M_KERNEL) != 0) {
129		object->type = OBJT_DEFAULT;
130		for (i = 0; i < c; i++)
131			rtvals[i] = VM_PAGER_FAIL;
132		return VM_PAGER_FAIL;
133	}
134
135	return swap_pager_putpages(object, m, c, sync, rtvals);
136}
137
138static boolean_t
139default_pager_haspage(object, pindex, before, after)
140	vm_object_t object;
141	vm_pindex_t pindex;
142	int *before;
143	int *after;
144{
145	return FALSE;
146}
147
148void
149default_pager_convert_to_swap(object)
150	vm_object_t object;
151{
152	object->type = OBJT_SWAP;
153	if (swap_pager_swp_alloc(object, M_KERNEL) != 0) {
154		object->type = OBJT_DEFAULT;
155	}
156}
157
158void
159default_pager_convert_to_swapq(object)
160	vm_object_t object;
161{
162	if (object &&
163		(object->type == OBJT_DEFAULT) &&
164		(object != kernel_object && object != kmem_object) &&
165		(object->size > ((cnt.v_page_count - cnt.v_wire_count) / 4)))
166		default_pager_convert_to_swap(object);
167}
168
169