157 lines
5.4 KiB
C
157 lines
5.4 KiB
C
/*
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* Copyright (c) 1995, David Greenman
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by David Greenman.
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* 4. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* The default pager is responsible for supplying backing store to unbacked
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* storage. The backing store is usually swap so we just fall through to
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* the swap routines. However, since swap metadata has not been assigned,
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* the swap routines assign and manage the swap backing store through the
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* vm_page->swapblk field. The object is only converted when the page is
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* physically freed after having been cleaned and even then vm_page->swapblk
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* is maintained whenever a resident page also has swap backing store.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/lock.h>
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#include <sys/proc.h>
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#include <sys/mutex.h>
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#include <vm/vm.h>
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#include <vm/vm_object.h>
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#include <vm/vm_page.h>
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#include <vm/vm_pager.h>
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#include <vm/swap_pager.h>
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static vm_object_t default_pager_alloc(void *, vm_ooffset_t, vm_prot_t,
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vm_ooffset_t);
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static void default_pager_dealloc(vm_object_t);
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static int default_pager_getpages(vm_object_t, vm_page_t *, int, int);
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static void default_pager_putpages(vm_object_t, vm_page_t *, int,
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boolean_t, int *);
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static boolean_t default_pager_haspage(vm_object_t, vm_pindex_t, int *,
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int *);
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/*
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* pagerops for OBJT_DEFAULT - "default pager".
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*/
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struct pagerops defaultpagerops = {
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.pgo_alloc = default_pager_alloc,
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.pgo_dealloc = default_pager_dealloc,
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.pgo_getpages = default_pager_getpages,
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.pgo_putpages = default_pager_putpages,
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.pgo_haspage = default_pager_haspage,
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};
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/*
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* no_pager_alloc just returns an initialized object.
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*/
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static vm_object_t
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default_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
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vm_ooffset_t offset)
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{
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if (handle != NULL)
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panic("default_pager_alloc: handle specified");
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return vm_object_allocate(OBJT_DEFAULT, OFF_TO_IDX(round_page(offset + size)));
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}
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/*
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* deallocate resources associated with default objects. The default objects
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* have no special resources allocated to them, but the vm_page's being used
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* in this object might. Still, we do not have to do anything - we will free
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* the swapblk in the underlying vm_page's when we free the vm_page or
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* garbage collect the vm_page cache list.
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*/
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static void
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default_pager_dealloc(object)
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vm_object_t object;
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{
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/*
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* OBJT_DEFAULT objects have no special resources allocated to them.
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*/
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}
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/*
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* Load pages from backing store. Since OBJT_DEFAULT is converted to
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* OBJT_SWAP at the time a swap-backed vm_page_t is freed, we will never
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* see a vm_page with assigned swap here.
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*/
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static int
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default_pager_getpages(object, m, count, reqpage)
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vm_object_t object;
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vm_page_t *m;
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int count;
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int reqpage;
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{
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return VM_PAGER_FAIL;
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}
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/*
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* Store pages to backing store. We should assign swap and initiate
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* I/O. We do not actually convert the object to OBJT_SWAP here. The
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* object will be converted when the written-out vm_page_t is moved from the
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* cache to the free list.
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*/
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static void
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default_pager_putpages(object, m, c, sync, rtvals)
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vm_object_t object;
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vm_page_t *m;
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int c;
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boolean_t sync;
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int *rtvals;
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{
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swappagerops.pgo_putpages(object, m, c, sync, rtvals);
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}
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/*
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* Tell us whether the backing store for the requested (object,index) is
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* synchronized. i.e. tell us whether we can throw the page away and
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* reload it later. So, for example, if we are in the process of writing
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* the page to its backing store, or if no backing store has been assigned,
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* it is not yet synchronized.
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*
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* It is possible to have fully-synchronized swap assigned without the
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* object having been converted. We just call swap_pager_haspage() to
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* deal with it since it must already deal with it plus deal with swap
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* meta-data structures.
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*/
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static boolean_t
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default_pager_haspage(object, pindex, before, after)
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vm_object_t object;
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vm_pindex_t pindex;
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int *before;
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int *after;
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{
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return FALSE;
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}
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