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 * The default pager is responsible for supplying backing store to unbacked
32 * storage. The backing store is usually swap so we just fall through to
33 * the swap routines. However, since swap metadata has not been assigned,
34 * the swap routines assign and manage the swap backing store through the
35 * vm_page->swapblk field. The object is only converted when the page is
36 * physically freed after having been cleaned and even then vm_page->swapblk
37 * is maintained whenever a resident page also has swap backing store.
38 *
39 * $FreeBSD: head/sys/vm/default_pager.c 92748 2002-03-20 04:02:59Z jeff $
40 */
41
42#include <sys/param.h>
43#include <sys/systm.h>
44#include <sys/lock.h>
45#include <sys/proc.h>
46#include <sys/mutex.h>
47
48#include <vm/vm.h>
49#include <vm/vm_object.h>
50#include <vm/vm_page.h>
51#include <vm/vm_pager.h>
52#include <vm/swap_pager.h>
53
54static vm_object_t default_pager_alloc(void *, vm_ooffset_t, vm_prot_t,
55 vm_ooffset_t);
56static void default_pager_dealloc(vm_object_t);
57static int default_pager_getpages(vm_object_t, vm_page_t *, int, int);
58static void default_pager_putpages(vm_object_t, vm_page_t *, int,
59 boolean_t, int *);
60static boolean_t default_pager_haspage(vm_object_t, vm_pindex_t, int *,
61 int *);
62/*
63 * pagerops for OBJT_DEFAULT - "default pager".
64 */
65struct pagerops defaultpagerops = {
66 NULL,
67 default_pager_alloc,
68 default_pager_dealloc,
69 default_pager_getpages,
70 default_pager_putpages,
71 default_pager_haspage,
72 NULL
73};
74
75/*
76 * no_pager_alloc just returns an initialized object.
77 */
78static vm_object_t
79default_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
80 vm_ooffset_t offset)
81{
82 if (handle != NULL)
83 panic("default_pager_alloc: handle specified");
84
85 return vm_object_allocate(OBJT_DEFAULT, OFF_TO_IDX(round_page(offset + size)));
86}
87
88/*
89 * deallocate resources associated with default objects. The default objects
90 * have no special resources allocated to them, but the vm_page's being used
91 * in this object might. Still, we do not have to do anything - we will free
92 * the swapblk in the underlying vm_page's when we free the vm_page or
93 * garbage collect the vm_page cache list.
94 */
95static void
96default_pager_dealloc(object)
97 vm_object_t object;
98{
99 /*
100 * OBJT_DEFAULT objects have no special resources allocated to them.
101 */
102}
103
104/*
105 * Load pages from backing store. Since OBJT_DEFAULT is converted to
106 * OBJT_SWAP at the time a swap-backed vm_page_t is freed, we will never
107 * see a vm_page with assigned swap here.
108 */
109static int
110default_pager_getpages(object, m, count, reqpage)
111 vm_object_t object;
112 vm_page_t *m;
113 int count;
114 int reqpage;
115{
116 return VM_PAGER_FAIL;
117}
118
119/*
120 * Store pages to backing store. We should assign swap and initiate
121 * I/O. We do not actually convert the object to OBJT_SWAP here. The
122 * object will be converted when the written-out vm_page_t is moved from the
123 * cache to the free list.
124 */
125static void
126default_pager_putpages(object, m, c, sync, rtvals)
127 vm_object_t object;
128 vm_page_t *m;
129 int c;
130 boolean_t sync;
131 int *rtvals;
132{
133 swap_pager_putpages(object, m, c, sync, rtvals);
134}
135
136/*
137 * Tell us whether the backing store for the requested (object,index) is
138 * synchronized. i.e. tell us whether we can throw the page away and
139 * reload it later. So, for example, if we are in the process of writing
140 * the page to its backing store, or if no backing store has been assigned,
141 * it is not yet synchronized.
142 *
143 * It is possible to have fully-synchronized swap assigned without the
144 * object having been converted. We just call swap_pager_haspage() to
145 * deal with it since it must already deal with it plus deal with swap
146 * meta-data structures.
147 */
148static boolean_t
149default_pager_haspage(object, pindex, before, after)
150 vm_object_t object;
151 vm_pindex_t pindex;
152 int *before;
153 int *after;
154{
155 return FALSE;
156}
157