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