default_pager.c revision 116226
19514Sdg/* 29514Sdg * Copyright (c) 1995, David Greenman 39514Sdg * All rights reserved. 49514Sdg * 59514Sdg * Redistribution and use in source and binary forms, with or without 69514Sdg * modification, are permitted provided that the following conditions 79514Sdg * are met: 89514Sdg * 1. Redistributions of source code must retain the above copyright 99514Sdg * notice, this list of conditions and the following disclaimer. 109514Sdg * 2. Redistributions in binary form must reproduce the above copyright 119514Sdg * notice, this list of conditions and the following disclaimer in the 129514Sdg * documentation and/or other materials provided with the distribution. 139514Sdg * 3. All advertising materials mentioning features or use of this software 1458705Scharnier * must display the following acknowledgement: 159514Sdg * This product includes software developed by David Greenman. 169514Sdg * 4. The name of the author may not be used to endorse or promote products 179514Sdg * derived from this software without specific prior written permission. 189514Sdg * 199514Sdg * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 209514Sdg * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 219514Sdg * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 229514Sdg * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 239514Sdg * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 249514Sdg * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 259514Sdg * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 269514Sdg * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 279514Sdg * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 289514Sdg * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 299514Sdg * SUCH DAMAGE. 309514Sdg * 3142957Sdillon * The default pager is responsible for supplying backing store to unbacked 3242957Sdillon * storage. The backing store is usually swap so we just fall through to 3342957Sdillon * the swap routines. However, since swap metadata has not been assigned, 3442957Sdillon * the swap routines assign and manage the swap backing store through the 3542957Sdillon * vm_page->swapblk field. The object is only converted when the page is 3642957Sdillon * physically freed after having been cleaned and even then vm_page->swapblk 3742957Sdillon * is maintained whenever a resident page also has swap backing store. 389514Sdg */ 399514Sdg 40116226Sobrien#include <sys/cdefs.h> 41116226Sobrien__FBSDID("$FreeBSD: head/sys/vm/default_pager.c 116226 2003-06-11 23:50:51Z obrien $"); 42116226Sobrien 439513Sdg#include <sys/param.h> 449513Sdg#include <sys/systm.h> 4576827Salfred#include <sys/lock.h> 4679224Sdillon#include <sys/proc.h> 4776827Salfred#include <sys/mutex.h> 489513Sdg 499513Sdg#include <vm/vm.h> 5012662Sdg#include <vm/vm_object.h> 5112662Sdg#include <vm/vm_page.h> 529513Sdg#include <vm/vm_pager.h> 539513Sdg#include <vm/swap_pager.h> 549513Sdg 5592727Salfredstatic vm_object_t default_pager_alloc(void *, vm_ooffset_t, vm_prot_t, 5692727Salfred vm_ooffset_t); 5792727Salfredstatic void default_pager_dealloc(vm_object_t); 5892727Salfredstatic int default_pager_getpages(vm_object_t, vm_page_t *, int, int); 5992727Salfredstatic void default_pager_putpages(vm_object_t, vm_page_t *, int, 6092727Salfred boolean_t, int *); 6192727Salfredstatic boolean_t default_pager_haspage(vm_object_t, vm_pindex_t, int *, 6292727Salfred int *); 639513Sdg/* 649513Sdg * pagerops for OBJT_DEFAULT - "default pager". 659513Sdg */ 669513Sdgstruct pagerops defaultpagerops = { 679513Sdg NULL, 689513Sdg default_pager_alloc, 699513Sdg default_pager_dealloc, 709513Sdg default_pager_getpages, 719513Sdg default_pager_putpages, 729513Sdg default_pager_haspage, 739513Sdg NULL 749513Sdg}; 759513Sdg 769513Sdg/* 779513Sdg * no_pager_alloc just returns an initialized object. 789513Sdg */ 7912820Sphkstatic vm_object_t 8040286Sdgdefault_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 8128751Sbde vm_ooffset_t offset) 829513Sdg{ 839513Sdg if (handle != NULL) 849513Sdg panic("default_pager_alloc: handle specified"); 859513Sdg 8640286Sdg return vm_object_allocate(OBJT_DEFAULT, OFF_TO_IDX(round_page(offset + size))); 879513Sdg} 889513Sdg 8942957Sdillon/* 9042957Sdillon * deallocate resources associated with default objects. The default objects 9142957Sdillon * have no special resources allocated to them, but the vm_page's being used 9242957Sdillon * in this object might. Still, we do not have to do anything - we will free 9342957Sdillon * the swapblk in the underlying vm_page's when we free the vm_page or 9442957Sdillon * garbage collect the vm_page cache list. 9542957Sdillon */ 9612820Sphkstatic void 979513Sdgdefault_pager_dealloc(object) 989513Sdg vm_object_t object; 999513Sdg{ 1009513Sdg /* 1019513Sdg * OBJT_DEFAULT objects have no special resources allocated to them. 1029513Sdg */ 1039513Sdg} 1049513Sdg 1059513Sdg/* 10642957Sdillon * Load pages from backing store. Since OBJT_DEFAULT is converted to 10742957Sdillon * OBJT_SWAP at the time a swap-backed vm_page_t is freed, we will never 10842957Sdillon * see a vm_page with assigned swap here. 1099513Sdg */ 11012820Sphkstatic int 1119513Sdgdefault_pager_getpages(object, m, count, reqpage) 1129513Sdg vm_object_t object; 1139513Sdg vm_page_t *m; 1149513Sdg int count; 1159513Sdg int reqpage; 1169513Sdg{ 1179513Sdg return VM_PAGER_FAIL; 1189513Sdg} 1199513Sdg 12042957Sdillon/* 12142957Sdillon * Store pages to backing store. We should assign swap and initiate 12242957Sdillon * I/O. We do not actually convert the object to OBJT_SWAP here. The 12342957Sdillon * object will be converted when the written-out vm_page_t is moved from the 12442957Sdillon * cache to the free list. 12542957Sdillon */ 12643129Sdillonstatic void 1279513Sdgdefault_pager_putpages(object, m, c, sync, rtvals) 1289513Sdg vm_object_t object; 1299513Sdg vm_page_t *m; 1309513Sdg int c; 1319513Sdg boolean_t sync; 1329513Sdg int *rtvals; 1339513Sdg{ 13443129Sdillon swap_pager_putpages(object, m, c, sync, rtvals); 1359513Sdg} 1369513Sdg 13742957Sdillon/* 13842957Sdillon * Tell us whether the backing store for the requested (object,index) is 13942957Sdillon * synchronized. i.e. tell us whether we can throw the page away and 14042957Sdillon * reload it later. So, for example, if we are in the process of writing 14142957Sdillon * the page to its backing store, or if no backing store has been assigned, 14242957Sdillon * it is not yet synchronized. 14342957Sdillon * 14442957Sdillon * It is possible to have fully-synchronized swap assigned without the 14542957Sdillon * object having been converted. We just call swap_pager_haspage() to 14642957Sdillon * deal with it since it must already deal with it plus deal with swap 14742957Sdillon * meta-data structures. 14842957Sdillon */ 14912820Sphkstatic boolean_t 15012767Sdysondefault_pager_haspage(object, pindex, before, after) 1519513Sdg vm_object_t object; 15212767Sdyson vm_pindex_t pindex; 1539513Sdg int *before; 1549513Sdg int *after; 1559513Sdg{ 1569513Sdg return FALSE; 1579513Sdg} 15815978Sdyson 159