6c2a557edd
current process from the exclusive lock prior to initiating I/O.
This fixes a panic related to swap-backed VN disks
Reviewed by: Alan Cox <alc@cs.rice.edu>, David Greenman <dg@root.com>
609 lines
14 KiB
C
609 lines
14 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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* 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 the University of
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* California, Berkeley and its contributors.
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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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* $FreeBSD$
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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/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/buf.h>
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#include <sys/ucred.h>
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#include <sys/malloc.h>
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#include <sys/proc.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_prot.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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MALLOC_DEFINE(M_VMPGDATA, "VM pgdata", "XXX: VM pager private data");
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extern struct pagerops defaultpagerops;
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extern struct pagerops swappagerops;
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extern struct pagerops vnodepagerops;
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extern struct pagerops devicepagerops;
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int cluster_pbuf_freecnt = -1; /* unlimited to begin with */
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static int dead_pager_getpages __P((vm_object_t, vm_page_t *, int, int));
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static vm_object_t dead_pager_alloc __P((void *, vm_ooffset_t, vm_prot_t,
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vm_ooffset_t));
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static void dead_pager_putpages __P((vm_object_t, vm_page_t *, int, int, int *));
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static boolean_t dead_pager_haspage __P((vm_object_t, vm_pindex_t, int *, int *));
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static void dead_pager_dealloc __P((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(handle, size, prot, off)
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void *handle;
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vm_ooffset_t size;
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vm_prot_t prot;
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vm_ooffset_t off;
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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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NULL,
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dead_pager_alloc,
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dead_pager_dealloc,
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dead_pager_getpages,
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dead_pager_putpages,
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dead_pager_haspage,
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NULL
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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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&deadpagerops /* OBJT_DEAD */
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};
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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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#define PAGER_MAP_SIZE (8 * 1024 * 1024)
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int pager_map_size = PAGER_MAP_SIZE;
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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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void
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vm_pager_init()
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{
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struct pagerops **pgops;
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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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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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swapbkva = kmem_alloc_pageable(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, vm_prot_t prot,
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vm_ooffset_t off)
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{
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struct pagerops *ops;
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ops = pagertab[type];
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if (ops)
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return ((*ops->pgo_alloc) (handle, size, prot, off));
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return (NULL);
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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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(*pagertab[object->type]->pgo_dealloc) (object);
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}
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/*
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* vm_pager_strategy:
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*
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* called with no specific spl
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* Execute strategy routine directly to pager.
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*/
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void
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vm_pager_strategy(vm_object_t object, struct buf *bp)
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{
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if (pagertab[object->type]->pgo_strategy) {
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(*pagertab[object->type]->pgo_strategy)(object, bp);
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} else {
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bp->b_flags |= B_ERROR;
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bp->b_error = ENXIO;
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biodone(bp);
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}
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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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* vm_pager_page_inserted() - inline, see vm/vm_pager.h
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* vm_pager_page_removed() - inline, see vm/vm_pager.h
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*/
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#if 0
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/*
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* vm_pager_sync:
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*
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* Called by pageout daemon before going back to sleep.
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* Gives pagers a chance to clean up any completed async pageing
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* operations.
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*/
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void
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vm_pager_sync()
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{
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struct pagerops **pgops;
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for (pgops = pagertab; pgops < &pagertab[npagers]; pgops++)
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if (pgops && ((*pgops)->pgo_sync != NULL))
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(*(*pgops)->pgo_sync) ();
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}
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#endif
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vm_offset_t
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vm_pager_map_page(m)
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vm_page_t m;
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{
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vm_offset_t kva;
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kva = kmem_alloc_wait(pager_map, PAGE_SIZE);
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pmap_kenter(kva, VM_PAGE_TO_PHYS(m));
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return (kva);
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}
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void
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vm_pager_unmap_page(kva)
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vm_offset_t kva;
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{
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pmap_kremove(kva);
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kmem_free_wakeup(pager_map, kva, PAGE_SIZE);
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}
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vm_object_t
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vm_pager_object_lookup(pg_list, handle)
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register struct pagerlst *pg_list;
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void *handle;
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{
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register vm_object_t object;
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for (object = TAILQ_FIRST(pg_list); object != NULL; object = TAILQ_NEXT(object,pager_object_list))
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if (object->handle == handle)
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return (object);
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return (NULL);
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}
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/*
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* initialize a physical buffer
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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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bp->b_rcred = NOCRED;
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bp->b_wcred = NOCRED;
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bp->b_qindex = QUEUE_NONE;
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bp->b_data = (caddr_t) (MAXPHYS * (bp - swbuf)) + swapbkva;
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bp->b_kvabase = bp->b_data;
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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_error = 0;
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BUF_LOCK(bp, LK_EXCLUSIVE);
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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(pfreecnt)
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int *pfreecnt;
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{
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int s;
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struct buf *bp;
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s = splvm();
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for (;;) {
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if (pfreecnt) {
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while (*pfreecnt == 0) {
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tsleep(pfreecnt, 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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tsleep(&bswneeded, 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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splx(s);
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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(pfreecnt)
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int *pfreecnt;
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{
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int s;
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struct buf *bp;
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s = splvm();
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if (*pfreecnt == 0 || (bp = TAILQ_FIRST(&bswlist)) == NULL) {
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splx(s);
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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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splx(s);
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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(bp, pfreecnt)
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struct buf *bp;
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int *pfreecnt;
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{
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int s;
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s = splvm();
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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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if (bp->b_vp)
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pbrelvp(bp);
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BUF_UNLOCK(bp);
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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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splx(s);
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}
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/********************************************************
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* CHAINING FUNCTIONS *
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********************************************************
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*
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* These functions support recursion of I/O operations
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* on bp's, typically by chaining one or more 'child' bp's
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* to the parent. Synchronous, asynchronous, and semi-synchronous
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* chaining is possible.
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*/
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/*
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* vm_pager_chain_iodone:
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*
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* io completion routine for child bp. Currently we fudge a bit
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* on dealing with b_resid. Since users of these routines may issue
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* multiple children simultaniously, sequencing of the error can be lost.
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*/
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static void
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vm_pager_chain_iodone(struct buf *nbp)
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{
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struct buf *bp;
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if ((bp = nbp->b_chain.parent) != NULL) {
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if (nbp->b_flags & B_ERROR) {
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bp->b_flags |= B_ERROR;
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bp->b_error = nbp->b_error;
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} else if (nbp->b_resid != 0) {
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bp->b_flags |= B_ERROR;
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bp->b_error = EINVAL;
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} else {
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bp->b_resid -= nbp->b_bcount;
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}
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nbp->b_chain.parent = NULL;
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--bp->b_chain.count;
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if (bp->b_flags & B_WANT) {
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bp->b_flags &= ~B_WANT;
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wakeup(bp);
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}
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if (!bp->b_chain.count && (bp->b_flags & B_AUTOCHAINDONE)) {
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bp->b_flags &= ~B_AUTOCHAINDONE;
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if (bp->b_resid != 0 && !(bp->b_flags & B_ERROR)) {
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bp->b_flags |= B_ERROR;
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bp->b_error = EINVAL;
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}
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biodone(bp);
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}
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}
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nbp->b_flags |= B_DONE;
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nbp->b_flags &= ~B_ASYNC;
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relpbuf(nbp, NULL);
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}
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/*
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* getchainbuf:
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*
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* Obtain a physical buffer and chain it to its parent buffer. When
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* I/O completes, the parent buffer will be B_SIGNAL'd. Errors are
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|
* automatically propogated to the parent
|
|
*
|
|
* Since these are brand new buffers, we do not have to clear B_INVAL
|
|
* and B_ERROR because they are already clear.
|
|
*/
|
|
|
|
struct buf *
|
|
getchainbuf(struct buf *bp, struct vnode *vp, int flags)
|
|
{
|
|
struct buf *nbp = getpbuf(NULL);
|
|
|
|
nbp->b_chain.parent = bp;
|
|
++bp->b_chain.count;
|
|
|
|
if (bp->b_chain.count > 4)
|
|
waitchainbuf(bp, 4, 0);
|
|
|
|
nbp->b_flags = B_CALL | (bp->b_flags & B_ORDERED) | flags;
|
|
nbp->b_rcred = nbp->b_wcred = proc0.p_ucred;
|
|
nbp->b_iodone = vm_pager_chain_iodone;
|
|
|
|
crhold(nbp->b_rcred);
|
|
crhold(nbp->b_wcred);
|
|
|
|
if (vp)
|
|
pbgetvp(vp, nbp);
|
|
return(nbp);
|
|
}
|
|
|
|
void
|
|
flushchainbuf(struct buf *nbp)
|
|
{
|
|
if (nbp->b_bcount) {
|
|
nbp->b_bufsize = nbp->b_bcount;
|
|
if ((nbp->b_flags & B_READ) == 0)
|
|
nbp->b_dirtyend = nbp->b_bcount;
|
|
BUF_KERNPROC(nbp);
|
|
VOP_STRATEGY(nbp->b_vp, nbp);
|
|
} else {
|
|
biodone(nbp);
|
|
}
|
|
}
|
|
|
|
void
|
|
waitchainbuf(struct buf *bp, int count, int done)
|
|
{
|
|
int s;
|
|
|
|
s = splbio();
|
|
while (bp->b_chain.count > count) {
|
|
bp->b_flags |= B_WANT;
|
|
tsleep(bp, PRIBIO + 4, "bpchain", 0);
|
|
}
|
|
if (done) {
|
|
if (bp->b_resid != 0 && !(bp->b_flags & B_ERROR)) {
|
|
bp->b_flags |= B_ERROR;
|
|
bp->b_error = EINVAL;
|
|
}
|
|
biodone(bp);
|
|
}
|
|
splx(s);
|
|
}
|
|
|
|
void
|
|
autochaindone(struct buf *bp)
|
|
{
|
|
int s;
|
|
|
|
s = splbio();
|
|
if (bp->b_chain.count == 0)
|
|
biodone(bp);
|
|
else
|
|
bp->b_flags |= B_AUTOCHAINDONE;
|
|
splx(s);
|
|
}
|
|
|