kernel - Adjust pagezero/pagecopy assembly and re-enable VM_ALLOC_ZERO
[dragonfly.git] / sys / vm / default_pager.c
CommitLineData
984263bc 1/*
99ad9bc4 2 * (MPSAFE)
8e7c4729 3 *
984263bc
MD
4 * Copyright (c) 1995, David Greenman
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. All advertising materials mentioning features or use of this software
16 * must display the following acknowledgement:
17 * This product includes software developed by David Greenman.
18 * 4. The name of the author may not be used to endorse or promote products
19 * derived from this software without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 *
33 * The default pager is responsible for supplying backing store to unbacked
34 * storage. The backing store is usually swap so we just fall through to
35 * the swap routines. However, since swap metadata has not been assigned,
36 * the swap routines assign and manage the swap backing store through the
37 * vm_page->swapblk field. The object is only converted when the page is
38 * physically freed after having been cleaned and even then vm_page->swapblk
39 * is maintained whenever a resident page also has swap backing store.
40 *
41 * $FreeBSD: src/sys/vm/default_pager.c,v 1.23 1999/11/07 20:03:53 alc Exp $
42 */
43
44#include <sys/param.h>
45#include <sys/systm.h>
46
47#include <vm/vm.h>
48#include <vm/vm_object.h>
49#include <vm/vm_page.h>
50#include <vm/vm_pager.h>
51#include <vm/swap_pager.h>
52
1388df65 53static void default_pager_dealloc (vm_object_t);
1b9d3514 54static int default_pager_getpage (vm_object_t, vm_page_t *, int);
1388df65
RG
55static void default_pager_putpages (vm_object_t, vm_page_t *, int,
56 boolean_t, int *);
1b9d3514 57static boolean_t default_pager_haspage (vm_object_t, vm_pindex_t);
984263bc
MD
58/*
59 * pagerops for OBJT_DEFAULT - "default pager".
60 */
61struct pagerops defaultpagerops = {
984263bc 62 default_pager_dealloc,
1b9d3514 63 default_pager_getpage,
984263bc 64 default_pager_putpages,
107e9bcc 65 default_pager_haspage
984263bc
MD
66};
67
68/*
69 * no_pager_alloc just returns an initialized object.
70 */
5a648714 71vm_object_t
57f7b636 72default_pager_alloc(void *handle, off_t size, vm_prot_t prot, off_t offset)
984263bc 73{
aecf2182
MD
74 vm_object_t object;
75
984263bc
MD
76 if (handle != NULL)
77 panic("default_pager_alloc: handle specified");
78
aecf2182
MD
79 object = vm_object_allocate(OBJT_DEFAULT,
80 OFF_TO_IDX(round_page64(offset + size)));
81 return (object);
984263bc
MD
82}
83
84/*
85 * deallocate resources associated with default objects. The default objects
86 * have no special resources allocated to them, but the vm_page's being used
87 * in this object might. Still, we do not have to do anything - we will free
88 * the swapblk in the underlying vm_page's when we free the vm_page or
89 * garbage collect the vm_page cache list.
90 */
984263bc 91static void
57e43348 92default_pager_dealloc(vm_object_t object)
984263bc
MD
93{
94 /*
95 * OBJT_DEFAULT objects have no special resources allocated to them.
96 */
8d292090 97 KKASSERT(object->swblock_count == 0);
984263bc
MD
98}
99
100/*
101 * Load pages from backing store. Since OBJT_DEFAULT is converted to
102 * OBJT_SWAP at the time a swap-backed vm_page_t is freed, we will never
103 * see a vm_page with assigned swap here.
104 */
984263bc 105static int
1b9d3514 106default_pager_getpage(vm_object_t object, vm_page_t *mpp, int seqaccess)
984263bc
MD
107{
108 return VM_PAGER_FAIL;
109}
110
111/*
112 * Store pages to backing store. We should assign swap and initiate
113 * I/O. We do not actually convert the object to OBJT_SWAP here. The
114 * object will be converted when the written-out vm_page_t is moved from the
115 * cache to the free list.
116 */
984263bc 117static void
8e7c4729
MD
118default_pager_putpages(vm_object_t object, vm_page_t *mpp, int count,
119 boolean_t sync, int *rtvals)
984263bc 120{
8e7c4729 121 swap_pager_putpages(object, mpp, count, sync, rtvals);
984263bc
MD
122}
123
124/*
125 * Tell us whether the backing store for the requested (object,index) is
126 * synchronized. i.e. tell us whether we can throw the page away and
127 * reload it later. So, for example, if we are in the process of writing
128 * the page to its backing store, or if no backing store has been assigned,
129 * it is not yet synchronized.
130 *
131 * It is possible to have fully-synchronized swap assigned without the
132 * object having been converted. We just call swap_pager_haspage() to
133 * deal with it since it must already deal with it plus deal with swap
134 * meta-data structures.
135 */
984263bc 136static boolean_t
1b9d3514 137default_pager_haspage(vm_object_t object, vm_pindex_t pindex)
984263bc
MD
138{
139 return FALSE;
140}