1 /* 2 * (MPSAFE) 3 * 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 53 static pgo_dealloc_t default_pager_dealloc; 54 static pgo_getpage_t default_pager_getpage; 55 static pgo_putpages_t default_pager_putpages; 56 static pgo_haspage_t default_pager_haspage; 57 58 /* 59 * pagerops for OBJT_DEFAULT - "default pager". 60 */ 61 struct pagerops defaultpagerops = { 62 .pgo_dealloc = default_pager_dealloc, 63 .pgo_getpage = default_pager_getpage, 64 .pgo_putpages = default_pager_putpages, 65 .pgo_haspage = default_pager_haspage 66 }; 67 68 /* 69 * no_pager_alloc just returns an initialized object. 70 */ 71 vm_object_t 72 default_pager_alloc(void *handle, off_t size, vm_prot_t prot, off_t offset) 73 { 74 vm_object_t object; 75 76 if (handle != NULL) 77 panic("default_pager_alloc: handle specified"); 78 79 object = vm_object_allocate(OBJT_DEFAULT, 80 OFF_TO_IDX(round_page64(offset + size))); 81 return (object); 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 */ 91 static void 92 default_pager_dealloc(vm_object_t object) 93 { 94 /* 95 * OBJT_DEFAULT objects have no special resources allocated to them. 96 */ 97 KKASSERT(object->swblock_count == 0); 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 */ 105 static int 106 default_pager_getpage(vm_object_t object, vm_pindex_t pindex, 107 vm_page_t *mpp, int seqaccess) 108 { 109 return VM_PAGER_FAIL; 110 } 111 112 /* 113 * Store pages to backing store. We should assign swap and initiate 114 * I/O. We do not actually convert the object to OBJT_SWAP here. The 115 * object will be converted when the written-out vm_page_t is moved from the 116 * cache to the free list. 117 */ 118 static void 119 default_pager_putpages(vm_object_t object, vm_page_t *mpp, int count, 120 int flags, int *rtvals) 121 { 122 swap_pager_putpages(object, mpp, count, flags, rtvals); 123 } 124 125 /* 126 * Tell us whether the backing store for the requested (object,index) is 127 * synchronized. i.e. tell us whether we can throw the page away and 128 * reload it later. So, for example, if we are in the process of writing 129 * the page to its backing store, or if no backing store has been assigned, 130 * it is not yet synchronized. 131 * 132 * It is possible to have fully-synchronized swap assigned without the 133 * object having been converted. We just call swap_pager_haspage() to 134 * deal with it since it must already deal with it plus deal with swap 135 * meta-data structures. 136 */ 137 static boolean_t 138 default_pager_haspage(vm_object_t object, vm_pindex_t pindex) 139 { 140 return FALSE; 141 } 142