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 1.2 2003/06/17 04:29:00 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>
83 #include <vm/vm_param.h>
84 #include <vm/vm_object.h>
85 #include <vm/vm_page.h>
86 #include <vm/vm_pager.h>
87 #include <vm/vm_extern.h>
89 MALLOC_DEFINE(M_VMPGDATA, "VM pgdata", "XXX: VM pager private data");
91 extern struct pagerops defaultpagerops;
92 extern struct pagerops swappagerops;
93 extern struct pagerops vnodepagerops;
94 extern struct pagerops devicepagerops;
95 extern struct pagerops physpagerops;
97 int cluster_pbuf_freecnt = -1; /* unlimited to begin with */
99 static int dead_pager_getpages __P((vm_object_t, vm_page_t *, int, int));
100 static vm_object_t dead_pager_alloc __P((void *, vm_ooffset_t, vm_prot_t,
102 static void dead_pager_putpages __P((vm_object_t, vm_page_t *, int, int, int *));
103 static boolean_t dead_pager_haspage __P((vm_object_t, vm_pindex_t, int *, int *));
104 static void dead_pager_dealloc __P((vm_object_t));
107 dead_pager_getpages(obj, ma, count, req)
113 return VM_PAGER_FAIL;
117 dead_pager_alloc(handle, size, prot, off)
127 dead_pager_putpages(object, m, count, flags, rtvals)
136 for (i = 0; i < count; i++) {
137 rtvals[i] = VM_PAGER_AGAIN;
142 dead_pager_haspage(object, pindex, prev, next)
156 dead_pager_dealloc(object)
162 static struct pagerops deadpagerops = {
172 struct pagerops *pagertab[] = {
173 &defaultpagerops, /* OBJT_DEFAULT */
174 &swappagerops, /* OBJT_SWAP */
175 &vnodepagerops, /* OBJT_VNODE */
176 &devicepagerops, /* OBJT_DEVICE */
177 &physpagerops, /* OBJT_PHYS */
178 &deadpagerops /* OBJT_DEAD */
181 int npagers = sizeof(pagertab) / sizeof(pagertab[0]);
184 * Kernel address space for mapping pages.
185 * Used by pagers where KVAs are needed for IO.
187 * XXX needs to be large enough to support the number of pending async
188 * cleaning requests (NPENDINGIO == 64) * the maximum swap cluster size
189 * (MAXPHYS == 64k) if you want to get the most efficiency.
191 #define PAGER_MAP_SIZE (8 * 1024 * 1024)
193 int pager_map_size = PAGER_MAP_SIZE;
195 static int bswneeded;
196 static vm_offset_t swapbkva; /* swap buffers kva */
201 struct pagerops **pgops;
204 * Initialize known pagers
206 for (pgops = pagertab; pgops < &pagertab[npagers]; pgops++)
207 if (pgops && ((*pgops)->pgo_init != NULL))
208 (*(*pgops)->pgo_init) ();
212 vm_pager_bufferinit()
219 * Now set up swap and physical I/O buffer headers.
221 for (i = 0; i < nswbuf; i++, bp++) {
222 TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist);
224 LIST_INIT(&bp->b_dep);
225 bp->b_rcred = bp->b_wcred = NOCRED;
229 cluster_pbuf_freecnt = nswbuf / 2;
231 swapbkva = kmem_alloc_pageable(pager_map, nswbuf * MAXPHYS);
233 panic("Not enough pager_map VM space for physical buffers");
237 * Allocate an instance of a pager of the given type.
238 * Size, protection and offset parameters are passed in for pagers that
239 * need to perform page-level validation (e.g. the device pager).
242 vm_pager_allocate(objtype_t type, void *handle, vm_ooffset_t size, vm_prot_t prot,
245 struct pagerops *ops;
247 ops = pagertab[type];
249 return ((*ops->pgo_alloc) (handle, size, prot, off));
254 vm_pager_deallocate(object)
257 (*pagertab[object->type]->pgo_dealloc) (object);
263 * called with no specific spl
264 * Execute strategy routine directly to pager.
268 vm_pager_strategy(vm_object_t object, struct buf *bp)
270 if (pagertab[object->type]->pgo_strategy) {
271 (*pagertab[object->type]->pgo_strategy)(object, bp);
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) ();
313 kva = kmem_alloc_wait(pager_map, PAGE_SIZE);
314 pmap_kenter(kva, VM_PAGE_TO_PHYS(m));
319 vm_pager_unmap_page(kva)
323 kmem_free_wakeup(pager_map, kva, PAGE_SIZE);
327 vm_pager_object_lookup(pg_list, handle)
328 register struct pagerlst *pg_list;
331 register vm_object_t object;
333 for (object = TAILQ_FIRST(pg_list); object != NULL; object = TAILQ_NEXT(object,pager_object_list))
334 if (object->handle == handle)
340 * initialize a physical buffer
344 initpbuf(struct buf *bp)
346 bp->b_rcred = NOCRED;
347 bp->b_wcred = NOCRED;
348 bp->b_qindex = QUEUE_NONE;
349 bp->b_data = (caddr_t) (MAXPHYS * (bp - swbuf)) + swapbkva;
350 bp->b_kvabase = bp->b_data;
351 bp->b_kvasize = MAXPHYS;
355 BUF_LOCK(bp, LK_EXCLUSIVE);
359 * allocate a physical buffer
361 * There are a limited number (nswbuf) of physical buffers. We need
362 * to make sure that no single subsystem is able to hog all of them,
363 * so each subsystem implements a counter which is typically initialized
364 * to 1/2 nswbuf. getpbuf() decrements this counter in allocation and
365 * increments it on release, and blocks if the counter hits zero. A
366 * subsystem may initialize the counter to -1 to disable the feature,
367 * but it must still be sure to match up all uses of getpbuf() with
368 * relpbuf() using the same variable.
370 * NOTE: pfreecnt can be NULL, but this 'feature' will be removed
371 * relatively soon when the rest of the subsystems get smart about it. XXX
384 while (*pfreecnt == 0) {
385 tsleep(pfreecnt, PVM, "wswbuf0", 0);
389 /* get a bp from the swap buffer header pool */
390 if ((bp = TAILQ_FIRST(&bswlist)) != NULL)
394 tsleep(&bswneeded, PVM, "wswbuf1", 0);
395 /* loop in case someone else grabbed one */
397 TAILQ_REMOVE(&bswlist, bp, b_freelist);
407 * allocate a physical buffer, if one is available.
409 * Note that there is no NULL hack here - all subsystems using this
410 * call understand how to use pfreecnt.
420 if (*pfreecnt == 0 || (bp = TAILQ_FIRST(&bswlist)) == NULL) {
424 TAILQ_REMOVE(&bswlist, bp, b_freelist);
436 * release a physical buffer
438 * NOTE: pfreecnt can be NULL, but this 'feature' will be removed
439 * relatively soon when the rest of the subsystems get smart about it. XXX
442 relpbuf(bp, pfreecnt)
450 if (bp->b_rcred != NOCRED) {
452 bp->b_rcred = NOCRED;
454 if (bp->b_wcred != NOCRED) {
456 bp->b_wcred = NOCRED;
464 TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist);
471 if (++*pfreecnt == 1)
477 /********************************************************
478 * CHAINING FUNCTIONS *
479 ********************************************************
481 * These functions support recursion of I/O operations
482 * on bp's, typically by chaining one or more 'child' bp's
483 * to the parent. Synchronous, asynchronous, and semi-synchronous
484 * chaining is possible.
488 * vm_pager_chain_iodone:
490 * io completion routine for child bp. Currently we fudge a bit
491 * on dealing with b_resid. Since users of these routines may issue
492 * multiple children simultaniously, sequencing of the error can be lost.
496 vm_pager_chain_iodone(struct buf *nbp)
500 if ((bp = nbp->b_chain.parent) != NULL) {
501 if (nbp->b_flags & B_ERROR) {
502 bp->b_flags |= B_ERROR;
503 bp->b_error = nbp->b_error;
504 } else if (nbp->b_resid != 0) {
505 bp->b_flags |= B_ERROR;
506 bp->b_error = EINVAL;
508 bp->b_resid -= nbp->b_bcount;
510 nbp->b_chain.parent = NULL;
512 if (bp->b_flags & B_WANT) {
513 bp->b_flags &= ~B_WANT;
516 if (!bp->b_chain.count && (bp->b_xflags & BX_AUTOCHAINDONE)) {
517 bp->b_xflags &= ~BX_AUTOCHAINDONE;
518 if (bp->b_resid != 0 && !(bp->b_flags & B_ERROR)) {
519 bp->b_flags |= B_ERROR;
520 bp->b_error = EINVAL;
525 nbp->b_flags |= B_DONE;
526 nbp->b_flags &= ~B_ASYNC;
533 * Obtain a physical buffer and chain it to its parent buffer. When
534 * I/O completes, the parent buffer will be B_SIGNAL'd. Errors are
535 * automatically propogated to the parent
537 * Since these are brand new buffers, we do not have to clear B_INVAL
538 * and B_ERROR because they are already clear.
542 getchainbuf(struct buf *bp, struct vnode *vp, int flags)
544 struct buf *nbp = getpbuf(NULL);
546 nbp->b_chain.parent = bp;
549 if (bp->b_chain.count > 4)
550 waitchainbuf(bp, 4, 0);
552 nbp->b_flags = B_CALL | (bp->b_flags & B_ORDERED) | flags;
553 nbp->b_rcred = nbp->b_wcred = proc0.p_ucred;
554 nbp->b_iodone = vm_pager_chain_iodone;
556 crhold(nbp->b_rcred);
557 crhold(nbp->b_wcred);
565 flushchainbuf(struct buf *nbp)
568 nbp->b_bufsize = nbp->b_bcount;
569 if ((nbp->b_flags & B_READ) == 0)
570 nbp->b_dirtyend = nbp->b_bcount;
572 VOP_STRATEGY(nbp->b_vp, nbp);
579 waitchainbuf(struct buf *bp, int count, int done)
584 while (bp->b_chain.count > count) {
585 bp->b_flags |= B_WANT;
586 tsleep(bp, PRIBIO + 4, "bpchain", 0);
589 if (bp->b_resid != 0 && !(bp->b_flags & B_ERROR)) {
590 bp->b_flags |= B_ERROR;
591 bp->b_error = EINVAL;
599 autochaindone(struct buf *bp)
604 if (bp->b_chain.count == 0)
607 bp->b_xflags |= BX_AUTOCHAINDONE;