3d026d871f
in this file actually described the operation of the swap pager, not the default pager. Given that this is the wrong place to discuss the implementation of the swap pager, it shouldn't come as a surprise that as the swap pager evolved these comments became increasingly stale. In addition, apply some style fixes, like modernizing a few remaining old- style function definitions. Reviewed by: kib, markj MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D8781
148 lines
4.4 KiB
C
148 lines
4.4 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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#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/resourcevar.h>
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#include <sys/rwlock.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, struct ucred *);
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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,
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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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* Return 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, struct ucred *cred)
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{
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vm_object_t object;
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if (handle != NULL)
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panic("default_pager_alloc: handle specified");
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if (cred != NULL) {
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if (!swap_reserve_by_cred(size, cred))
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return (NULL);
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crhold(cred);
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}
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object = vm_object_allocate(OBJT_DEFAULT,
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OFF_TO_IDX(round_page(offset + size)));
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if (cred != NULL) {
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VM_OBJECT_WLOCK(object);
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object->cred = cred;
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object->charge = size;
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VM_OBJECT_WUNLOCK(object);
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}
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return (object);
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}
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/*
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* Deallocate resources associated with the object.
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*/
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static void
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default_pager_dealloc(vm_object_t object)
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{
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/* Reserved swap is released by vm_object_destroy(). */
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object->type = OBJT_DEAD;
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}
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/*
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* Load pages from backing store.
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*/
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static int
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default_pager_getpages(vm_object_t object, vm_page_t *m, int count,
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int *rbehind, int *rahead)
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{
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/*
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* Since an OBJT_DEFAULT object is converted to OBJT_SWAP by the first
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* call to the putpages method, this function will never be called on
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* a vm_page with assigned swap.
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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.
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*/
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static void
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default_pager_putpages(vm_object_t object, vm_page_t *m, int count,
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int flags, int *rtvals)
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{
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/* The swap pager will convert the object to OBJT_SWAP. */
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swappagerops.pgo_putpages(object, m, count, flags, rtvals);
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}
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/*
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* Tell us whether the requested (object,index) is available from the object's
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* backing store.
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*/
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static boolean_t
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default_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
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int *after)
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{
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/* An OBJT_DEFAULT object has no backing store. */
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return (FALSE);
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}
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