156 lines
4.8 KiB
C
156 lines
4.8 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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* This pager handles anonymous (no handle) swap-backed memory, just
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* like the swap pager. It allows several optimizations based on the
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* fact that no pages of a default object can be swapped out. The
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* most important optimization is in vm_fault(), where the pager is
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* never asked for a non-resident page. Instead, a freshly allocated
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* zeroed page is used.
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*
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* On the first request to page out a page from a default object, the
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* object is converted to swap pager type.
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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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object->cred = cred;
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object->charge = size;
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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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