508 lines
12 KiB
C
508 lines
12 KiB
C
/*-
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* Copyright (c) 1991, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* The Mach Operating System project at Carnegie-Mellon University.
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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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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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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* from: @(#)vm_pager.c 8.6 (Berkeley) 1/12/94
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*
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*
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* Copyright (c) 1987, 1990 Carnegie-Mellon University.
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* All rights reserved.
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*
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* Authors: Avadis Tevanian, Jr., Michael Wayne Young
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*
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* Permission to use, copy, modify and distribute this software and
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* its documentation is hereby granted, provided that both the copyright
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* notice and this permission notice appear in all copies of the
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* software, derivative works or modified versions, and any portions
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* thereof, and that both notices appear in supporting documentation.
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*
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* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
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* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
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* FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
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*
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* Carnegie Mellon requests users of this software to return to
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*
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* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
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* School of Computer Science
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* Carnegie Mellon University
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* Pittsburgh PA 15213-3890
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*
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* any improvements or extensions that they make and grant Carnegie the
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* rights to redistribute these changes.
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*/
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/*
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* Paging space routine stubs. Emulates a matchmaker-like interface
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* for builtin pagers.
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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/kernel.h>
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#include <sys/vnode.h>
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#include <sys/bio.h>
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#include <sys/buf.h>
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#include <sys/ucred.h>
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#include <sys/malloc.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_extern.h>
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int cluster_pbuf_freecnt = -1; /* unlimited to begin with */
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static int dead_pager_getpages(vm_object_t, vm_page_t *, int, int);
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static vm_object_t dead_pager_alloc(void *, vm_ooffset_t, vm_prot_t,
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vm_ooffset_t, struct ucred *);
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static void dead_pager_putpages(vm_object_t, vm_page_t *, int, int, int *);
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static boolean_t dead_pager_haspage(vm_object_t, vm_pindex_t, int *, int *);
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static void dead_pager_dealloc(vm_object_t);
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static int
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dead_pager_getpages(obj, ma, count, req)
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vm_object_t obj;
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vm_page_t *ma;
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int count;
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int req;
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{
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return VM_PAGER_FAIL;
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}
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static vm_object_t
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dead_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
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vm_ooffset_t off, struct ucred *cred)
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{
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return NULL;
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}
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static void
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dead_pager_putpages(object, m, count, flags, rtvals)
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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 flags;
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int *rtvals;
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{
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int i;
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for (i = 0; i < count; i++) {
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rtvals[i] = VM_PAGER_AGAIN;
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}
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}
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static int
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dead_pager_haspage(object, pindex, prev, next)
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vm_object_t object;
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vm_pindex_t pindex;
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int *prev;
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int *next;
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{
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if (prev)
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*prev = 0;
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if (next)
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*next = 0;
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return FALSE;
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}
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static void
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dead_pager_dealloc(object)
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vm_object_t object;
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{
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return;
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}
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static struct pagerops deadpagerops = {
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.pgo_alloc = dead_pager_alloc,
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.pgo_dealloc = dead_pager_dealloc,
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.pgo_getpages = dead_pager_getpages,
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.pgo_putpages = dead_pager_putpages,
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.pgo_haspage = dead_pager_haspage,
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};
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struct pagerops *pagertab[] = {
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&defaultpagerops, /* OBJT_DEFAULT */
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&swappagerops, /* OBJT_SWAP */
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&vnodepagerops, /* OBJT_VNODE */
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&devicepagerops, /* OBJT_DEVICE */
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&physpagerops, /* OBJT_PHYS */
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&deadpagerops, /* OBJT_DEAD */
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&sgpagerops /* OBJT_SG */
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};
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static const int npagers = sizeof(pagertab) / sizeof(pagertab[0]);
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/*
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* Kernel address space for mapping pages.
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* Used by pagers where KVAs are needed for IO.
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*
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* XXX needs to be large enough to support the number of pending async
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* cleaning requests (NPENDINGIO == 64) * the maximum swap cluster size
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* (MAXPHYS == 64k) if you want to get the most efficiency.
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*/
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vm_map_t pager_map;
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static int bswneeded;
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static vm_offset_t swapbkva; /* swap buffers kva */
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struct mtx pbuf_mtx;
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static TAILQ_HEAD(swqueue, buf) bswlist;
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void
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vm_pager_init()
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{
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struct pagerops **pgops;
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TAILQ_INIT(&bswlist);
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/*
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* Initialize known pagers
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*/
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for (pgops = pagertab; pgops < &pagertab[npagers]; pgops++)
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if (pgops && ((*pgops)->pgo_init != NULL))
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(*(*pgops)->pgo_init) ();
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}
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void
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vm_pager_bufferinit()
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{
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struct buf *bp;
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int i;
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mtx_init(&pbuf_mtx, "pbuf mutex", NULL, MTX_DEF);
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bp = swbuf;
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/*
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* Now set up swap and physical I/O buffer headers.
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*/
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for (i = 0; i < nswbuf; i++, bp++) {
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TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist);
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BUF_LOCKINIT(bp);
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LIST_INIT(&bp->b_dep);
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bp->b_rcred = bp->b_wcred = NOCRED;
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bp->b_xflags = 0;
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}
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cluster_pbuf_freecnt = nswbuf / 2;
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vnode_pbuf_freecnt = nswbuf / 2 + 1;
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swapbkva = kmem_alloc_nofault(pager_map, nswbuf * MAXPHYS);
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if (!swapbkva)
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panic("Not enough pager_map VM space for physical buffers");
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}
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/*
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* Allocate an instance of a pager of the given type.
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* Size, protection and offset parameters are passed in for pagers that
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* need to perform page-level validation (e.g. the device pager).
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*/
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vm_object_t
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vm_pager_allocate(objtype_t type, void *handle, vm_ooffset_t size,
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vm_prot_t prot, vm_ooffset_t off, struct ucred *cred)
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{
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vm_object_t ret;
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struct pagerops *ops;
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ops = pagertab[type];
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if (ops)
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ret = (*ops->pgo_alloc) (handle, size, prot, off, cred);
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else
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ret = NULL;
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return (ret);
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}
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/*
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* The object must be locked.
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*/
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void
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vm_pager_deallocate(object)
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vm_object_t object;
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{
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VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
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(*pagertab[object->type]->pgo_dealloc) (object);
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}
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/*
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* vm_pager_get_pages() - inline, see vm/vm_pager.h
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* vm_pager_put_pages() - inline, see vm/vm_pager.h
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* vm_pager_has_page() - inline, see vm/vm_pager.h
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*/
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/*
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* Search the specified pager object list for an object with the
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* specified handle. If an object with the specified handle is found,
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* increase its reference count and return it. Otherwise, return NULL.
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*
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* The pager object list must be locked.
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*/
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vm_object_t
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vm_pager_object_lookup(struct pagerlst *pg_list, void *handle)
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{
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vm_object_t object;
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TAILQ_FOREACH(object, pg_list, pager_object_list) {
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VM_OBJECT_LOCK(object);
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if (object->handle == handle &&
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(object->flags & OBJ_DEAD) == 0) {
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vm_object_reference_locked(object);
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VM_OBJECT_UNLOCK(object);
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break;
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}
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VM_OBJECT_UNLOCK(object);
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}
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return (object);
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}
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/*
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* initialize a physical buffer
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*/
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/*
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* XXX This probably belongs in vfs_bio.c
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*/
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static void
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initpbuf(struct buf *bp)
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{
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KASSERT(bp->b_bufobj == NULL, ("initpbuf with bufobj"));
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KASSERT(bp->b_vp == NULL, ("initpbuf with vp"));
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bp->b_rcred = NOCRED;
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bp->b_wcred = NOCRED;
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bp->b_qindex = 0; /* On no queue (QUEUE_NONE) */
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bp->b_saveaddr = (caddr_t) (MAXPHYS * (bp - swbuf)) + swapbkva;
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bp->b_data = bp->b_saveaddr;
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bp->b_kvabase = bp->b_saveaddr;
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bp->b_kvasize = MAXPHYS;
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bp->b_xflags = 0;
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bp->b_flags = 0;
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bp->b_ioflags = 0;
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bp->b_iodone = NULL;
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bp->b_error = 0;
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BUF_LOCK(bp, LK_EXCLUSIVE, NULL);
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}
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/*
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* allocate a physical buffer
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*
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* There are a limited number (nswbuf) of physical buffers. We need
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* to make sure that no single subsystem is able to hog all of them,
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* so each subsystem implements a counter which is typically initialized
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* to 1/2 nswbuf. getpbuf() decrements this counter in allocation and
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* increments it on release, and blocks if the counter hits zero. A
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* subsystem may initialize the counter to -1 to disable the feature,
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* but it must still be sure to match up all uses of getpbuf() with
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* relpbuf() using the same variable.
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*
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* NOTE: pfreecnt can be NULL, but this 'feature' will be removed
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* relatively soon when the rest of the subsystems get smart about it. XXX
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*/
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struct buf *
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getpbuf(int *pfreecnt)
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{
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struct buf *bp;
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mtx_lock(&pbuf_mtx);
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for (;;) {
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if (pfreecnt) {
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while (*pfreecnt == 0) {
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msleep(pfreecnt, &pbuf_mtx, PVM, "wswbuf0", 0);
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}
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}
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/* get a bp from the swap buffer header pool */
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if ((bp = TAILQ_FIRST(&bswlist)) != NULL)
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break;
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bswneeded = 1;
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msleep(&bswneeded, &pbuf_mtx, PVM, "wswbuf1", 0);
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/* loop in case someone else grabbed one */
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}
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TAILQ_REMOVE(&bswlist, bp, b_freelist);
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if (pfreecnt)
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--*pfreecnt;
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mtx_unlock(&pbuf_mtx);
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initpbuf(bp);
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return bp;
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}
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/*
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* allocate a physical buffer, if one is available.
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*
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* Note that there is no NULL hack here - all subsystems using this
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* call understand how to use pfreecnt.
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*/
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struct buf *
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trypbuf(int *pfreecnt)
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{
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struct buf *bp;
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mtx_lock(&pbuf_mtx);
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if (*pfreecnt == 0 || (bp = TAILQ_FIRST(&bswlist)) == NULL) {
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mtx_unlock(&pbuf_mtx);
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return NULL;
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}
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TAILQ_REMOVE(&bswlist, bp, b_freelist);
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--*pfreecnt;
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mtx_unlock(&pbuf_mtx);
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initpbuf(bp);
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return bp;
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}
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/*
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* release a physical buffer
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*
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* NOTE: pfreecnt can be NULL, but this 'feature' will be removed
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* relatively soon when the rest of the subsystems get smart about it. XXX
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*/
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void
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relpbuf(struct buf *bp, int *pfreecnt)
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{
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if (bp->b_rcred != NOCRED) {
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crfree(bp->b_rcred);
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bp->b_rcred = NOCRED;
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}
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if (bp->b_wcred != NOCRED) {
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crfree(bp->b_wcred);
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bp->b_wcred = NOCRED;
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}
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KASSERT(bp->b_vp == NULL, ("relpbuf with vp"));
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KASSERT(bp->b_bufobj == NULL, ("relpbuf with bufobj"));
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BUF_UNLOCK(bp);
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mtx_lock(&pbuf_mtx);
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TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist);
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if (bswneeded) {
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bswneeded = 0;
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wakeup(&bswneeded);
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}
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if (pfreecnt) {
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if (++*pfreecnt == 1)
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wakeup(pfreecnt);
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}
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mtx_unlock(&pbuf_mtx);
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}
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/*
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* Associate a p-buffer with a vnode.
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*
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* Also sets B_PAGING flag to indicate that vnode is not fully associated
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* with the buffer. i.e. the bp has not been linked into the vnode or
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* ref-counted.
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*/
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void
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pbgetvp(struct vnode *vp, struct buf *bp)
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{
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KASSERT(bp->b_vp == NULL, ("pbgetvp: not free"));
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KASSERT(bp->b_bufobj == NULL, ("pbgetvp: not free (bufobj)"));
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bp->b_vp = vp;
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bp->b_flags |= B_PAGING;
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bp->b_bufobj = &vp->v_bufobj;
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}
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/*
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* Associate a p-buffer with a vnode.
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*
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* Also sets B_PAGING flag to indicate that vnode is not fully associated
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* with the buffer. i.e. the bp has not been linked into the vnode or
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* ref-counted.
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*/
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void
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pbgetbo(struct bufobj *bo, struct buf *bp)
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{
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KASSERT(bp->b_vp == NULL, ("pbgetbo: not free (vnode)"));
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KASSERT(bp->b_bufobj == NULL, ("pbgetbo: not free (bufobj)"));
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bp->b_flags |= B_PAGING;
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bp->b_bufobj = bo;
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}
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/*
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* Disassociate a p-buffer from a vnode.
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*/
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void
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pbrelvp(struct buf *bp)
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{
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KASSERT(bp->b_vp != NULL, ("pbrelvp: NULL"));
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KASSERT(bp->b_bufobj != NULL, ("pbrelvp: NULL bufobj"));
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/* XXX REMOVE ME */
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BO_LOCK(bp->b_bufobj);
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if (TAILQ_NEXT(bp, b_bobufs) != NULL) {
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panic(
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"relpbuf(): b_vp was probably reassignbuf()d %p %x",
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bp,
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(int)bp->b_flags
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);
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}
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BO_UNLOCK(bp->b_bufobj);
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bp->b_vp = NULL;
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bp->b_bufobj = NULL;
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bp->b_flags &= ~B_PAGING;
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}
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/*
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* Disassociate a p-buffer from a bufobj.
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*/
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void
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pbrelbo(struct buf *bp)
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{
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KASSERT(bp->b_vp == NULL, ("pbrelbo: vnode"));
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KASSERT(bp->b_bufobj != NULL, ("pbrelbo: NULL bufobj"));
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/* XXX REMOVE ME */
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BO_LOCK(bp->b_bufobj);
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if (TAILQ_NEXT(bp, b_bobufs) != NULL) {
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panic(
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"relpbuf(): b_vp was probably reassignbuf()d %p %x",
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bp,
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(int)bp->b_flags
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);
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}
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BO_UNLOCK(bp->b_bufobj);
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bp->b_bufobj = NULL;
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bp->b_flags &= ~B_PAGING;
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}
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