2 * Copyright (c) 1991, 1993
3 * The Regents of the University of California. All rights reserved.
5 * This code is derived from software contributed to Berkeley by
6 * The Mach Operating System project at Carnegie-Mellon University.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 * must display the following acknowledgement:
18 * This product includes software developed by the University of
19 * California, Berkeley and its contributors.
20 * 4. Neither the name of the University nor the names of its contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * from: @(#)vm_pager.c 8.6 (Berkeley) 1/12/94
39 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
40 * All rights reserved.
42 * Authors: Avadis Tevanian, Jr., Michael Wayne Young
44 * Permission to use, copy, modify and distribute this software and
45 * its documentation is hereby granted, provided that both the copyright
46 * notice and this permission notice appear in all copies of the
47 * software, derivative works or modified versions, and any portions
48 * thereof, and that both notices appear in supporting documentation.
50 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
51 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
52 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
54 * Carnegie Mellon requests users of this software to return to
56 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
57 * School of Computer Science
58 * Carnegie Mellon University
59 * Pittsburgh PA 15213-3890
61 * any improvements or extensions that they make and grant Carnegie the
62 * rights to redistribute these changes.
64 * $FreeBSD: src/sys/vm/vm_pager.c,v 1.54.2.2 2001/11/18 07:11:00 dillon Exp $
65 * $DragonFly: src/sys/vm/vm_pager.c,v 1.24 2007/11/06 03:50:01 dillon Exp $
69 * Paging space routine stubs. Emulates a matchmaker-like interface
73 #include <sys/param.h>
74 #include <sys/systm.h>
75 #include <sys/kernel.h>
76 #include <sys/vnode.h>
78 #include <sys/ucred.h>
79 #include <sys/malloc.h>
81 #include <sys/thread2.h>
84 #include <vm/vm_param.h>
85 #include <vm/vm_object.h>
86 #include <vm/vm_page.h>
87 #include <vm/vm_pager.h>
88 #include <vm/vm_extern.h>
92 MALLOC_DEFINE(M_VMPGDATA, "VM pgdata", "XXX: VM pager private data");
94 extern struct pagerops defaultpagerops;
95 extern struct pagerops swappagerops;
96 extern struct pagerops vnodepagerops;
97 extern struct pagerops devicepagerops;
98 extern struct pagerops physpagerops;
100 int cluster_pbuf_freecnt = -1; /* unlimited to begin with */
102 static int dead_pager_getpages (vm_object_t, vm_page_t *, int, int);
103 static vm_object_t dead_pager_alloc (void *, off_t, vm_prot_t, off_t);
104 static void dead_pager_putpages (vm_object_t, vm_page_t *, int, int, int *);
105 static boolean_t dead_pager_haspage (vm_object_t, vm_pindex_t, int *, int *);
106 static void dead_pager_dealloc (vm_object_t);
109 dead_pager_getpages(vm_object_t obj, vm_page_t *ma, int count, int req)
111 return VM_PAGER_FAIL;
115 dead_pager_alloc(void *handle, off_t size, vm_prot_t prot, off_t off)
121 dead_pager_putpages(vm_object_t object, vm_page_t *m, int count, int flags,
126 for (i = 0; i < count; i++) {
127 rtvals[i] = VM_PAGER_AGAIN;
132 dead_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *prev, int *next)
142 dead_pager_dealloc(vm_object_t object)
147 static struct pagerops deadpagerops = {
157 struct pagerops *pagertab[] = {
158 &defaultpagerops, /* OBJT_DEFAULT */
159 &swappagerops, /* OBJT_SWAP */
160 &vnodepagerops, /* OBJT_VNODE */
161 &devicepagerops, /* OBJT_DEVICE */
162 &physpagerops, /* OBJT_PHYS */
163 &deadpagerops /* OBJT_DEAD */
166 int npagers = sizeof(pagertab) / sizeof(pagertab[0]);
169 * Kernel address space for mapping pages.
170 * Used by pagers where KVAs are needed for IO.
172 * XXX needs to be large enough to support the number of pending async
173 * cleaning requests (NPENDINGIO == 64) * the maximum swap cluster size
174 * (MAXPHYS == 64k) if you want to get the most efficiency.
176 #define PAGER_MAP_SIZE (8 * 1024 * 1024)
178 int pager_map_size = PAGER_MAP_SIZE;
179 struct vm_map pager_map;
181 static int bswneeded;
182 static vm_offset_t swapbkva; /* swap buffers kva */
183 static TAILQ_HEAD(swqueue, buf) bswlist;
188 struct pagerops **pgops;
191 * Initialize the swap buffer list.
193 TAILQ_INIT(&bswlist);
196 * Initialize known pagers
198 for (pgops = pagertab; pgops < &pagertab[npagers]; pgops++)
199 if (pgops && ((*pgops)->pgo_init != NULL))
200 (*(*pgops)->pgo_init) ();
204 vm_pager_bufferinit(void)
210 * Reserve KVM space for pbuf data.
212 swapbkva = kmem_alloc_pageable(&pager_map, nswbuf * MAXPHYS);
214 panic("Not enough pager_map VM space for physical buffers");
217 * Initial pbuf setup.
220 for (i = 0; i < nswbuf; ++i, ++bp) {
221 bp->b_kvabase = (caddr_t)((intptr_t)i * MAXPHYS) + swapbkva;
222 bp->b_kvasize = MAXPHYS;
223 TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist);
229 * Allow the clustering code to use half of our pbufs.
231 cluster_pbuf_freecnt = nswbuf / 2;
235 * Allocate an instance of a pager of the given type.
236 * Size, protection and offset parameters are passed in for pagers that
237 * need to perform page-level validation (e.g. the device pager).
240 vm_pager_allocate(objtype_t type, void *handle, vm_ooffset_t size,
241 vm_prot_t prot, off_t off)
243 struct pagerops *ops;
245 ops = pagertab[type];
247 return ((*ops->pgo_alloc) (handle, size, prot, off));
252 vm_pager_deallocate(vm_object_t object)
254 (*pagertab[object->type]->pgo_dealloc) (object);
260 * called with no specific spl
261 * Execute strategy routine directly to pager.
265 vm_pager_strategy(vm_object_t object, struct bio *bio)
269 if (pagertab[object->type]->pgo_strategy) {
270 (*pagertab[object->type]->pgo_strategy)(object, bio);
273 bp->b_flags |= B_ERROR;
280 * vm_pager_get_pages() - inline, see vm/vm_pager.h
281 * vm_pager_put_pages() - inline, see vm/vm_pager.h
282 * vm_pager_has_page() - inline, see vm/vm_pager.h
283 * vm_pager_page_inserted() - inline, see vm/vm_pager.h
284 * vm_pager_page_removed() - inline, see vm/vm_pager.h
291 * Called by pageout daemon before going back to sleep.
292 * Gives pagers a chance to clean up any completed async pageing
298 struct pagerops **pgops;
300 for (pgops = pagertab; pgops < &pagertab[npagers]; pgops++)
301 if (pgops && ((*pgops)->pgo_sync != NULL))
302 (*(*pgops)->pgo_sync) ();
308 vm_pager_object_lookup(struct pagerlst *pg_list, void *handle)
312 for (object = TAILQ_FIRST(pg_list); object != NULL; object = TAILQ_NEXT(object,pager_object_list))
313 if (object->handle == handle)
319 * Initialize a physical buffer.
322 initpbuf(struct buf *bp)
324 bp->b_qindex = 0; /* BQUEUE_NONE */
325 bp->b_data = bp->b_kvabase;
326 bp->b_flags = B_PAGING;
327 bp->b_cmd = BUF_CMD_DONE;
330 bp->b_bufsize = MAXPHYS;
332 xio_init(&bp->b_xio);
333 BUF_LOCK(bp, LK_EXCLUSIVE);
337 * allocate a physical buffer
339 * There are a limited number (nswbuf) of physical buffers. We need
340 * to make sure that no single subsystem is able to hog all of them,
341 * so each subsystem implements a counter which is typically initialized
342 * to 1/2 nswbuf. getpbuf() decrements this counter in allocation and
343 * increments it on release, and blocks if the counter hits zero. A
344 * subsystem may initialize the counter to -1 to disable the feature,
345 * but it must still be sure to match up all uses of getpbuf() with
346 * relpbuf() using the same variable.
348 * NOTE: pfreecnt can be NULL, but this 'feature' will be removed
349 * relatively soon when the rest of the subsystems get smart about it. XXX
352 getpbuf(int *pfreecnt)
360 while (*pfreecnt == 0) {
361 tsleep(pfreecnt, 0, "wswbuf0", 0);
365 /* get a bp from the swap buffer header pool */
366 if ((bp = TAILQ_FIRST(&bswlist)) != NULL)
370 tsleep(&bswneeded, 0, "wswbuf1", 0);
371 /* loop in case someone else grabbed one */
373 TAILQ_REMOVE(&bswlist, bp, b_freelist);
383 * allocate a physical buffer, if one is available.
385 * Note that there is no NULL hack here - all subsystems using this
386 * call understand how to use pfreecnt.
389 trypbuf(int *pfreecnt)
394 if (*pfreecnt == 0 || (bp = TAILQ_FIRST(&bswlist)) == NULL) {
398 TAILQ_REMOVE(&bswlist, bp, b_freelist);
410 * release a physical buffer
412 * NOTE: pfreecnt can be NULL, but this 'feature' will be removed
413 * relatively soon when the rest of the subsystems get smart about it. XXX
416 relpbuf(struct buf *bp, int *pfreecnt)
420 KKASSERT(bp->b_flags & B_PAGING);
423 TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist);
430 if (++*pfreecnt == 1)