225 lines
6.2 KiB
C
225 lines
6.2 KiB
C
/*-
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* Copyright (c) 2009 Hudson River Trading LLC
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* Written by: John H. Baldwin <jhb@FreeBSD.org>
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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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*
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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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/*
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* This pager manages OBJT_SG objects. These objects are backed by
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* a scatter/gather list of physical address ranges.
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*/
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#include <sys/param.h>
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#include <sys/lock.h>
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#include <sys/mutex.h>
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#include <sys/rwlock.h>
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#include <sys/sglist.h>
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#include <vm/vm.h>
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#include <vm/vm_param.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/vm_phys.h>
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#include <vm/uma.h>
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static vm_object_t sg_pager_alloc(void *, vm_ooffset_t, vm_prot_t,
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vm_ooffset_t, struct ucred *);
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static void sg_pager_dealloc(vm_object_t);
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static int sg_pager_getpages(vm_object_t, vm_page_t *, int, int *, int *);
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static void sg_pager_putpages(vm_object_t, vm_page_t *, int,
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boolean_t, int *);
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static boolean_t sg_pager_haspage(vm_object_t, vm_pindex_t, int *,
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int *);
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struct pagerops sgpagerops = {
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.pgo_alloc = sg_pager_alloc,
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.pgo_dealloc = sg_pager_dealloc,
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.pgo_getpages = sg_pager_getpages,
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.pgo_putpages = sg_pager_putpages,
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.pgo_haspage = sg_pager_haspage,
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};
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static vm_object_t
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sg_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
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vm_ooffset_t foff, struct ucred *cred)
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{
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struct sglist *sg;
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vm_object_t object;
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vm_pindex_t npages, pindex;
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int i;
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/*
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* Offset should be page aligned.
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*/
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if (foff & PAGE_MASK)
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return (NULL);
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/*
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* The scatter/gather list must only include page-aligned
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* ranges.
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*/
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npages = 0;
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sg = handle;
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for (i = 0; i < sg->sg_nseg; i++) {
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if ((sg->sg_segs[i].ss_paddr % PAGE_SIZE) != 0 ||
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(sg->sg_segs[i].ss_len % PAGE_SIZE) != 0)
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return (NULL);
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npages += sg->sg_segs[i].ss_len / PAGE_SIZE;
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}
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/*
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* The scatter/gather list has a fixed size. Refuse requests
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* to map beyond that.
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*/
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size = round_page(size);
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pindex = OFF_TO_IDX(foff + size);
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if (pindex > npages)
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return (NULL);
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/*
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* Allocate a new object and associate it with the
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* scatter/gather list. It is ok for our purposes to have
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* multiple VM objects associated with the same scatter/gather
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* list because scatter/gather lists are static. This is also
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* simpler than ensuring a unique object per scatter/gather
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* list.
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*/
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object = vm_object_allocate(OBJT_SG, npages);
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object->handle = sglist_hold(sg);
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TAILQ_INIT(&object->un_pager.sgp.sgp_pglist);
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return (object);
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}
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static void
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sg_pager_dealloc(vm_object_t object)
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{
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struct sglist *sg;
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vm_page_t m;
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/*
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* Free up our fake pages.
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*/
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while ((m = TAILQ_FIRST(&object->un_pager.sgp.sgp_pglist)) != 0) {
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TAILQ_REMOVE(&object->un_pager.sgp.sgp_pglist, m, plinks.q);
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vm_page_putfake(m);
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}
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sg = object->handle;
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sglist_free(sg);
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object->handle = NULL;
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object->type = OBJT_DEAD;
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}
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static int
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sg_pager_getpages(vm_object_t object, vm_page_t *m, int count, int *rbehind,
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int *rahead)
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{
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struct sglist *sg;
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vm_page_t m_paddr, page;
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vm_pindex_t offset;
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vm_paddr_t paddr;
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vm_memattr_t memattr;
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size_t space;
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int i;
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/* Since our haspage reports zero after/before, the count is 1. */
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KASSERT(count == 1, ("%s: count %d", __func__, count));
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VM_OBJECT_ASSERT_WLOCKED(object);
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sg = object->handle;
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memattr = object->memattr;
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VM_OBJECT_WUNLOCK(object);
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offset = m[0]->pindex;
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/*
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* Lookup the physical address of the requested page. An initial
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* value of '1' instead of '0' is used so we can assert that the
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* page is found since '0' can be a valid page-aligned physical
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* address.
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*/
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space = 0;
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paddr = 1;
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for (i = 0; i < sg->sg_nseg; i++) {
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if (space + sg->sg_segs[i].ss_len <= (offset * PAGE_SIZE)) {
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space += sg->sg_segs[i].ss_len;
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continue;
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}
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paddr = sg->sg_segs[i].ss_paddr + offset * PAGE_SIZE - space;
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break;
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}
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KASSERT(paddr != 1, ("invalid SG page index"));
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/* If "paddr" is a real page, perform a sanity check on "memattr". */
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if ((m_paddr = vm_phys_paddr_to_vm_page(paddr)) != NULL &&
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pmap_page_get_memattr(m_paddr) != memattr) {
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memattr = pmap_page_get_memattr(m_paddr);
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printf(
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"WARNING: A device driver has set \"memattr\" inconsistently.\n");
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}
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/* Return a fake page for the requested page. */
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KASSERT(!(m[0]->flags & PG_FICTITIOUS),
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("backing page for SG is fake"));
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/* Construct a new fake page. */
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page = vm_page_getfake(paddr, memattr);
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VM_OBJECT_WLOCK(object);
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TAILQ_INSERT_TAIL(&object->un_pager.sgp.sgp_pglist, page, plinks.q);
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vm_page_replace_checked(page, object, offset, m[0]);
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vm_page_lock(m[0]);
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vm_page_free(m[0]);
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vm_page_unlock(m[0]);
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m[0] = page;
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page->valid = VM_PAGE_BITS_ALL;
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if (rbehind)
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*rbehind = 0;
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if (rahead)
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*rahead = 0;
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return (VM_PAGER_OK);
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}
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static void
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sg_pager_putpages(vm_object_t object, vm_page_t *m, int count,
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boolean_t sync, int *rtvals)
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{
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panic("sg_pager_putpage called");
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}
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static boolean_t
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sg_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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if (before != NULL)
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*before = 0;
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if (after != NULL)
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*after = 0;
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return (TRUE);
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}
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