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