default_pager.c revision 40286 
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 1.15 1998/02/06 12:14:20 eivind Exp $
32 */
33
34#include <sys/param.h>
35#include <sys/systm.h>
36#include <sys/malloc.h>
37#include <sys/vmmeter.h>
38
39#include <vm/vm.h>
40#include <vm/vm_prot.h>
41#include <vm/vm_object.h>
42#include <vm/vm_page.h>
43#include <vm/vm_pager.h>
44#include <vm/default_pager.h>
45#include <vm/swap_pager.h>
46
47static vm_object_t default_pager_alloc __P((void *, vm_ooffset_t, vm_prot_t,
48		vm_ooffset_t));
49static void default_pager_dealloc __P((vm_object_t));
50static int default_pager_getpages __P((vm_object_t, vm_page_t *, int, int));
51static int default_pager_putpages __P((vm_object_t, vm_page_t *, int,
52		boolean_t, int *));
53static boolean_t default_pager_haspage __P((vm_object_t, vm_pindex_t, int *,
54		int *));
55/*
56 * pagerops for OBJT_DEFAULT - "default pager".
57 */
58struct pagerops defaultpagerops = {
59	NULL,
60	default_pager_alloc,
61	default_pager_dealloc,
62	default_pager_getpages,
63	default_pager_putpages,
64	default_pager_haspage,
65	NULL
66};
67
68/*
69 * no_pager_alloc just returns an initialized object.
70 */
71static vm_object_t
72default_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
73		    vm_ooffset_t offset)
74{
75	if (handle != NULL)
76		panic("default_pager_alloc: handle specified");
77
78	return vm_object_allocate(OBJT_DEFAULT, OFF_TO_IDX(round_page(offset + size)));
79}
80
81static void
82default_pager_dealloc(object)
83	vm_object_t object;
84{
85	/*
86	 * OBJT_DEFAULT objects have no special resources allocated to them.
87	 */
88}
89
90/*
91 * The default pager has no backing store, so we always return
92 * failure.
93 */
94static int
95default_pager_getpages(object, m, count, reqpage)
96	vm_object_t object;
97	vm_page_t *m;
98	int count;
99	int reqpage;
100{
101	return VM_PAGER_FAIL;
102}
103
104static int
105default_pager_putpages(object, m, c, sync, rtvals)
106	vm_object_t object;
107	vm_page_t *m;
108	int c;
109	boolean_t sync;
110	int *rtvals;
111{
112	int i;
113
114	/*
115	 * Try to convert the object type into a OBJT_SWAP.
116	 * If the swp structure allocation fails, convert it
117	 * back to OBJT_DEFAULT and return failure. Otherwise
118	 * pass this putpages to the swap pager.
119	 */
120	object->type = OBJT_SWAP;
121
122	if (swap_pager_swp_alloc(object, M_KERNEL) != 0) {
123		object->type = OBJT_DEFAULT;
124		for (i = 0; i < c; i++)
125			rtvals[i] = VM_PAGER_FAIL;
126		return VM_PAGER_FAIL;
127	}
128
129	return swap_pager_putpages(object, m, c, sync, rtvals);
130}
131
132static boolean_t
133default_pager_haspage(object, pindex, before, after)
134	vm_object_t object;
135	vm_pindex_t pindex;
136	int *before;
137	int *after;
138{
139	return FALSE;
140}
141
142void
143default_pager_convert_to_swap(object)
144	vm_object_t object;
145{
146	object->type = OBJT_SWAP;
147	if (swap_pager_swp_alloc(object, M_KERNEL) != 0) {
148		object->type = OBJT_DEFAULT;
149	}
150}
151
152void
153default_pager_convert_to_swapq(object)
154	vm_object_t object;
155{
156	if (object &&
157		(object->type == OBJT_DEFAULT) &&
158		(object != kernel_object && object != kmem_object) &&
159		(object->size > ((cnt.v_page_count - cnt.v_wire_count) / 4)))
160		default_pager_convert_to_swap(object);
161}
162
163