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 1.15 2005/08/08 16:53:12 hmp 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 *, vm_ooffset_t, vm_prot_t,
105 static void dead_pager_putpages (vm_object_t, vm_page_t *, int, int, int *);
106 static boolean_t dead_pager_haspage (vm_object_t, vm_pindex_t, int *, int *);
107 static void dead_pager_dealloc (vm_object_t);
110 dead_pager_getpages(vm_object_t obj, vm_page_t *ma, int count, int req)
112 return VM_PAGER_FAIL;
116 dead_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
123 dead_pager_putpages(vm_object_t object, vm_page_t *m, int count, int flags,
128 for (i = 0; i < count; i++) {
129 rtvals[i] = VM_PAGER_AGAIN;
134 dead_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *prev, int *next)
144 dead_pager_dealloc(vm_object_t object)
149 static struct pagerops deadpagerops = {
159 struct pagerops *pagertab[] = {
160 &defaultpagerops, /* OBJT_DEFAULT */
161 &swappagerops, /* OBJT_SWAP */
162 &vnodepagerops, /* OBJT_VNODE */
163 &devicepagerops, /* OBJT_DEVICE */
164 &physpagerops, /* OBJT_PHYS */
165 &deadpagerops /* OBJT_DEAD */
168 int npagers = sizeof(pagertab) / sizeof(pagertab[0]);
171 * Kernel address space for mapping pages.
172 * Used by pagers where KVAs are needed for IO.
174 * XXX needs to be large enough to support the number of pending async
175 * cleaning requests (NPENDINGIO == 64) * the maximum swap cluster size
176 * (MAXPHYS == 64k) if you want to get the most efficiency.
178 #define PAGER_MAP_SIZE (8 * 1024 * 1024)
180 int pager_map_size = PAGER_MAP_SIZE;
182 static int bswneeded;
183 static vm_offset_t swapbkva; /* swap buffers kva */
184 static TAILQ_HEAD(swqueue, buf) bswlist;
189 struct pagerops **pgops;
192 * Initialize the swap buffer list.
194 TAILQ_INIT(&bswlist);
197 * Initialize known pagers
199 for (pgops = pagertab; pgops < &pagertab[npagers]; pgops++)
200 if (pgops && ((*pgops)->pgo_init != NULL))
201 (*(*pgops)->pgo_init) ();
205 vm_pager_bufferinit(void)
212 * Now set up swap and physical I/O buffer headers.
214 for (i = 0; i < nswbuf; i++, bp++) {
215 TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist);
217 LIST_INIT(&bp->b_dep);
221 cluster_pbuf_freecnt = nswbuf / 2;
223 swapbkva = kmem_alloc_pageable(pager_map, nswbuf * MAXPHYS);
225 panic("Not enough pager_map VM space for physical buffers");
229 * Allocate an instance of a pager of the given type.
230 * Size, protection and offset parameters are passed in for pagers that
231 * need to perform page-level validation (e.g. the device pager).
234 vm_pager_allocate(objtype_t type, void *handle, vm_ooffset_t size, vm_prot_t prot,
237 struct pagerops *ops;
239 ops = pagertab[type];
241 return ((*ops->pgo_alloc) (handle, size, prot, off));
246 vm_pager_deallocate(vm_object_t object)
248 (*pagertab[object->type]->pgo_dealloc) (object);
254 * called with no specific spl
255 * Execute strategy routine directly to pager.
259 vm_pager_strategy(vm_object_t object, struct buf *bp)
261 if (pagertab[object->type]->pgo_strategy) {
262 (*pagertab[object->type]->pgo_strategy)(object, bp);
264 bp->b_flags |= B_ERROR;
271 * vm_pager_get_pages() - inline, see vm/vm_pager.h
272 * vm_pager_put_pages() - inline, see vm/vm_pager.h
273 * vm_pager_has_page() - inline, see vm/vm_pager.h
274 * vm_pager_page_inserted() - inline, see vm/vm_pager.h
275 * vm_pager_page_removed() - inline, see vm/vm_pager.h
282 * Called by pageout daemon before going back to sleep.
283 * Gives pagers a chance to clean up any completed async pageing
289 struct pagerops **pgops;
291 for (pgops = pagertab; pgops < &pagertab[npagers]; pgops++)
292 if (pgops && ((*pgops)->pgo_sync != NULL))
293 (*(*pgops)->pgo_sync) ();
299 vm_pager_object_lookup(struct pagerlst *pg_list, void *handle)
303 for (object = TAILQ_FIRST(pg_list); object != NULL; object = TAILQ_NEXT(object,pager_object_list))
304 if (object->handle == handle)
310 * initialize a physical buffer
314 initpbuf(struct buf *bp)
316 bp->b_qindex = 0; /* BQUEUE_NONE */
317 bp->b_data = (caddr_t) (MAXPHYS * (bp - swbuf)) + swapbkva;
318 bp->b_kvabase = bp->b_data;
319 bp->b_kvasize = MAXPHYS;
323 xio_init(&bp->b_xio);
324 BUF_LOCK(bp, LK_EXCLUSIVE);
328 * allocate a physical buffer
330 * There are a limited number (nswbuf) of physical buffers. We need
331 * to make sure that no single subsystem is able to hog all of them,
332 * so each subsystem implements a counter which is typically initialized
333 * to 1/2 nswbuf. getpbuf() decrements this counter in allocation and
334 * increments it on release, and blocks if the counter hits zero. A
335 * subsystem may initialize the counter to -1 to disable the feature,
336 * but it must still be sure to match up all uses of getpbuf() with
337 * relpbuf() using the same variable.
339 * NOTE: pfreecnt can be NULL, but this 'feature' will be removed
340 * relatively soon when the rest of the subsystems get smart about it. XXX
343 getpbuf(int *pfreecnt)
351 while (*pfreecnt == 0) {
352 tsleep(pfreecnt, 0, "wswbuf0", 0);
356 /* get a bp from the swap buffer header pool */
357 if ((bp = TAILQ_FIRST(&bswlist)) != NULL)
361 tsleep(&bswneeded, 0, "wswbuf1", 0);
362 /* loop in case someone else grabbed one */
364 TAILQ_REMOVE(&bswlist, bp, b_freelist);
374 * allocate a physical buffer, if one is available.
376 * Note that there is no NULL hack here - all subsystems using this
377 * call understand how to use pfreecnt.
380 trypbuf(int *pfreecnt)
385 if (*pfreecnt == 0 || (bp = TAILQ_FIRST(&bswlist)) == NULL) {
389 TAILQ_REMOVE(&bswlist, bp, b_freelist);
401 * release a physical buffer
403 * NOTE: pfreecnt can be NULL, but this 'feature' will be removed
404 * relatively soon when the rest of the subsystems get smart about it. XXX
407 relpbuf(struct buf *bp, int *pfreecnt)
416 TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist);
423 if (++*pfreecnt == 1)
429 /********************************************************
430 * CHAINING FUNCTIONS *
431 ********************************************************
433 * These functions support recursion of I/O operations
434 * on bp's, typically by chaining one or more 'child' bp's
435 * to the parent. Synchronous, asynchronous, and semi-synchronous
436 * chaining is possible.
440 * vm_pager_chain_iodone:
442 * io completion routine for child bp. Currently we fudge a bit
443 * on dealing with b_resid. Since users of these routines may issue
444 * multiple children simultaniously, sequencing of the error can be lost.
448 vm_pager_chain_iodone(struct buf *nbp)
452 if ((bp = nbp->b_chain.parent) != NULL) {
453 if (nbp->b_flags & B_ERROR) {
454 bp->b_flags |= B_ERROR;
455 bp->b_error = nbp->b_error;
456 } else if (nbp->b_resid != 0) {
457 bp->b_flags |= B_ERROR;
458 bp->b_error = EINVAL;
460 bp->b_resid -= nbp->b_bcount;
462 nbp->b_chain.parent = NULL;
464 if (bp->b_flags & B_WANT) {
465 bp->b_flags &= ~B_WANT;
468 if (!bp->b_chain.count && (bp->b_xflags & BX_AUTOCHAINDONE)) {
469 bp->b_xflags &= ~BX_AUTOCHAINDONE;
470 if (bp->b_resid != 0 && !(bp->b_flags & B_ERROR)) {
471 bp->b_flags |= B_ERROR;
472 bp->b_error = EINVAL;
477 nbp->b_flags |= B_DONE;
478 nbp->b_flags &= ~B_ASYNC;
485 * Obtain a physical buffer and chain it to its parent buffer. When
486 * I/O completes, the parent buffer will be B_SIGNAL'd. Errors are
487 * automatically propogated to the parent
489 * Since these are brand new buffers, we do not have to clear B_INVAL
490 * and B_ERROR because they are already clear.
494 getchainbuf(struct buf *bp, struct vnode *vp, int flags)
496 struct buf *nbp = getpbuf(NULL);
498 nbp->b_chain.parent = bp;
501 if (bp->b_chain.count > 4)
502 waitchainbuf(bp, 4, 0);
504 nbp->b_flags = (bp->b_flags & B_ORDERED) | flags;
505 nbp->b_iodone = vm_pager_chain_iodone;
513 flushchainbuf(struct buf *nbp)
516 nbp->b_bufsize = nbp->b_bcount;
517 if ((nbp->b_flags & B_READ) == 0)
518 nbp->b_dirtyend = nbp->b_bcount;
520 VOP_STRATEGY(nbp->b_vp, nbp);
527 waitchainbuf(struct buf *bp, int count, int done)
530 while (bp->b_chain.count > count) {
531 bp->b_flags |= B_WANT;
532 tsleep(bp, 0, "bpchain", 0);
535 if (bp->b_resid != 0 && !(bp->b_flags & B_ERROR)) {
536 bp->b_flags |= B_ERROR;
537 bp->b_error = EINVAL;
545 autochaindone(struct buf *bp)
548 if (bp->b_chain.count == 0)
551 bp->b_xflags |= BX_AUTOCHAINDONE;