default_pager.c revision 139825
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: head/sys/vm/default_pager.c 139825 2005-01-07 02:29:27Z imp $"); 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 55static vm_object_t default_pager_alloc(void *, vm_ooffset_t, vm_prot_t, 56 vm_ooffset_t); 57static void default_pager_dealloc(vm_object_t); 58static int default_pager_getpages(vm_object_t, vm_page_t *, int, int); 59static void default_pager_putpages(vm_object_t, vm_page_t *, int, 60 boolean_t, int *); 61static boolean_t default_pager_haspage(vm_object_t, vm_pindex_t, int *, 62 int *); 63/* 64 * pagerops for OBJT_DEFAULT - "default pager". 65 */ 66struct 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 */ 77static vm_object_t 78default_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 */ 94static void 95default_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 */ 108static int 109default_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 */ 124static void 125default_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 */ 147static boolean_t 148default_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} 156 157