2 * SPDX-License-Identifier: (BSD-3-Clause AND MIT-CMU)
4 * Copyright (c) 1991, 1993
5 * The Regents of the University of California. All rights reserved.
7 * This code is derived from software contributed to Berkeley by
8 * The Mach Operating System project at Carnegie-Mellon University.
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * from: @(#)vm_pager.c 8.6 (Berkeley) 1/12/94
37 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
38 * All rights reserved.
40 * Authors: Avadis Tevanian, Jr., Michael Wayne Young
42 * Permission to use, copy, modify and distribute this software and
43 * its documentation is hereby granted, provided that both the copyright
44 * notice and this permission notice appear in all copies of the
45 * software, derivative works or modified versions, and any portions
46 * thereof, and that both notices appear in supporting documentation.
48 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
49 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
50 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
52 * Carnegie Mellon requests users of this software to return to
54 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
55 * School of Computer Science
56 * Carnegie Mellon University
57 * Pittsburgh PA 15213-3890
59 * any improvements or extensions that they make and grant Carnegie the
60 * rights to redistribute these changes.
64 * Paging space routine stubs. Emulates a matchmaker-like interface
68 #include <sys/cdefs.h>
69 __FBSDID("$FreeBSD$");
71 #include "opt_param.h"
73 #include <sys/param.h>
74 #include <sys/systm.h>
75 #include <sys/kernel.h>
76 #include <sys/vnode.h>
79 #include <sys/ucred.h>
80 #include <sys/malloc.h>
81 #include <sys/rwlock.h>
84 #include <vm/vm_param.h>
85 #include <vm/vm_kern.h>
86 #include <vm/vm_object.h>
87 #include <vm/vm_page.h>
88 #include <vm/vm_pager.h>
89 #include <vm/vm_extern.h>
93 static int pbuf_init(void *, int, int);
94 static int pbuf_ctor(void *, int, void *, int);
95 static void pbuf_dtor(void *, int, void *);
97 static int dead_pager_getpages(vm_object_t, vm_page_t *, int, int *, int *);
98 static vm_object_t dead_pager_alloc(void *, vm_ooffset_t, vm_prot_t,
99 vm_ooffset_t, struct ucred *);
100 static void dead_pager_putpages(vm_object_t, vm_page_t *, int, int, int *);
101 static boolean_t dead_pager_haspage(vm_object_t, vm_pindex_t, int *, int *);
102 static void dead_pager_dealloc(vm_object_t);
105 dead_pager_getpages(vm_object_t obj, vm_page_t *ma, int count, int *rbehind,
109 return (VM_PAGER_FAIL);
113 dead_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
114 vm_ooffset_t off, struct ucred *cred)
121 dead_pager_putpages(vm_object_t object, vm_page_t *m, int count,
122 int flags, int *rtvals)
126 for (i = 0; i < count; i++)
127 rtvals[i] = VM_PAGER_AGAIN;
131 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 = {
148 .pgo_alloc = dead_pager_alloc,
149 .pgo_dealloc = dead_pager_dealloc,
150 .pgo_getpages = dead_pager_getpages,
151 .pgo_putpages = dead_pager_putpages,
152 .pgo_haspage = dead_pager_haspage,
155 struct pagerops *pagertab[] = {
156 &defaultpagerops, /* OBJT_DEFAULT */
157 &swappagerops, /* OBJT_SWAP */
158 &vnodepagerops, /* OBJT_VNODE */
159 &devicepagerops, /* OBJT_DEVICE */
160 &physpagerops, /* OBJT_PHYS */
161 &deadpagerops, /* OBJT_DEAD */
162 &sgpagerops, /* OBJT_SG */
163 &mgtdevicepagerops, /* OBJT_MGTDEVICE */
169 struct pagerops **pgops;
172 * Initialize known pagers
174 for (pgops = pagertab; pgops < &pagertab[nitems(pagertab)]; pgops++)
175 if ((*pgops)->pgo_init != NULL)
176 (*(*pgops)->pgo_init)();
179 static int nswbuf_max;
182 vm_pager_bufferinit(void)
185 /* Main zone for paging bufs. */
186 pbuf_zone = uma_zcreate("pbuf",
187 sizeof(struct buf) + PBUF_PAGES * sizeof(vm_page_t),
188 pbuf_ctor, pbuf_dtor, pbuf_init, NULL, UMA_ALIGN_CACHE,
190 /* Few systems may still use this zone directly, so it needs a limit. */
191 nswbuf_max += uma_zone_set_max(pbuf_zone, NSWBUF_MIN);
195 pbuf_zsecond_create(const char *name, int max)
199 zone = uma_zsecond_create(name, pbuf_ctor, pbuf_dtor, NULL, NULL,
202 * uma_prealloc() rounds up to items per slab. If we would prealloc
203 * immediately on every pbuf_zsecond_create(), we may accumulate too
204 * much of difference between hard limit and prealloced items, which
205 * means wasted memory.
208 nswbuf_max += uma_zone_set_max(zone, max);
210 uma_prealloc(pbuf_zone, uma_zone_set_max(zone, max));
216 pbuf_prealloc(void *arg __unused)
219 uma_prealloc(pbuf_zone, nswbuf_max);
223 SYSINIT(pbuf, SI_SUB_KTHREAD_BUF, SI_ORDER_ANY, pbuf_prealloc, NULL);
226 * Allocate an instance of a pager of the given type.
227 * Size, protection and offset parameters are passed in for pagers that
228 * need to perform page-level validation (e.g. the device pager).
231 vm_pager_allocate(objtype_t type, void *handle, vm_ooffset_t size,
232 vm_prot_t prot, vm_ooffset_t off, struct ucred *cred)
235 struct pagerops *ops;
237 ops = pagertab[type];
239 ret = (*ops->pgo_alloc)(handle, size, prot, off, cred);
246 * The object must be locked.
249 vm_pager_deallocate(vm_object_t object)
252 VM_OBJECT_ASSERT_WLOCKED(object);
253 (*pagertab[object->type]->pgo_dealloc) (object);
257 vm_pager_assert_in(vm_object_t object, vm_page_t *m, int count)
262 * All pages must be consecutive, busied, not mapped, not fully valid,
263 * not dirty and belong to the proper object. Some pages may be the
264 * bogus page, but the first and last pages must be a real ones.
267 VM_OBJECT_ASSERT_UNLOCKED(object);
268 VM_OBJECT_ASSERT_PAGING(object);
269 KASSERT(count > 0, ("%s: 0 count", __func__));
270 for (int i = 0 ; i < count; i++) {
271 if (m[i] == bogus_page) {
272 KASSERT(i != 0 && i != count - 1,
273 ("%s: page %d is the bogus page", __func__, i));
276 vm_page_assert_xbusied(m[i]);
277 KASSERT(!pmap_page_is_mapped(m[i]),
278 ("%s: page %p is mapped", __func__, m[i]));
279 KASSERT(m[i]->valid != VM_PAGE_BITS_ALL,
280 ("%s: request for a valid page %p", __func__, m[i]));
281 KASSERT(m[i]->dirty == 0,
282 ("%s: page %p is dirty", __func__, m[i]));
283 KASSERT(m[i]->object == object,
284 ("%s: wrong object %p/%p", __func__, object, m[i]->object));
285 KASSERT(m[i]->pindex == m[0]->pindex + i,
286 ("%s: page %p isn't consecutive", __func__, m[i]));
292 * Page in the pages for the object using its associated pager.
293 * The requested page must be fully valid on successful return.
296 vm_pager_get_pages(vm_object_t object, vm_page_t *m, int count, int *rbehind,
300 vm_pindex_t pindex = m[0]->pindex;
304 vm_pager_assert_in(object, m, count);
306 r = (*pagertab[object->type]->pgo_getpages)(object, m, count, rbehind,
308 if (r != VM_PAGER_OK)
311 for (int i = 0; i < count; i++) {
313 * If pager has replaced a page, assert that it had
317 VM_OBJECT_RLOCK(object);
318 KASSERT(m[i] == vm_page_lookup(object, pindex++),
319 ("%s: mismatch page %p pindex %ju", __func__,
320 m[i], (uintmax_t )pindex - 1));
321 VM_OBJECT_RUNLOCK(object);
324 * Zero out partially filled data.
326 if (m[i]->valid != VM_PAGE_BITS_ALL)
327 vm_page_zero_invalid(m[i], TRUE);
329 return (VM_PAGER_OK);
333 vm_pager_get_pages_async(vm_object_t object, vm_page_t *m, int count,
334 int *rbehind, int *rahead, pgo_getpages_iodone_t iodone, void *arg)
337 vm_pager_assert_in(object, m, count);
339 return ((*pagertab[object->type]->pgo_getpages_async)(object, m,
340 count, rbehind, rahead, iodone, arg));
344 * vm_pager_put_pages() - inline, see vm/vm_pager.h
345 * vm_pager_has_page() - inline, see vm/vm_pager.h
349 * Search the specified pager object list for an object with the
350 * specified handle. If an object with the specified handle is found,
351 * increase its reference count and return it. Otherwise, return NULL.
353 * The pager object list must be locked.
356 vm_pager_object_lookup(struct pagerlst *pg_list, void *handle)
360 TAILQ_FOREACH(object, pg_list, pager_object_list) {
361 if (object->handle == handle) {
362 VM_OBJECT_WLOCK(object);
363 if ((object->flags & OBJ_DEAD) == 0) {
364 vm_object_reference_locked(object);
365 VM_OBJECT_WUNLOCK(object);
368 VM_OBJECT_WUNLOCK(object);
375 pbuf_ctor(void *mem, int size, void *arg, int flags)
377 struct buf *bp = mem;
382 /* copied from initpbuf() */
383 bp->b_rcred = NOCRED;
384 bp->b_wcred = NOCRED;
385 bp->b_qindex = 0; /* On no queue (QUEUE_NONE) */
386 bp->b_data = bp->b_kvabase;
388 bp->b_flags = B_MAXPHYS;
392 BUF_LOCK(bp, LK_EXCLUSIVE, NULL);
398 pbuf_dtor(void *mem, int size, void *arg)
400 struct buf *bp = mem;
402 if (bp->b_rcred != NOCRED) {
404 bp->b_rcred = NOCRED;
406 if (bp->b_wcred != NOCRED) {
408 bp->b_wcred = NOCRED;
415 pbuf_init(void *mem, int size, int flags)
417 struct buf *bp = mem;
419 bp->b_kvabase = (void *)kva_alloc(ptoa(PBUF_PAGES));
420 if (bp->b_kvabase == NULL)
422 bp->b_kvasize = ptoa(PBUF_PAGES);
424 LIST_INIT(&bp->b_dep);
425 bp->b_rcred = bp->b_wcred = NOCRED;
432 * Associate a p-buffer with a vnode.
434 * Also sets B_PAGING flag to indicate that vnode is not fully associated
435 * with the buffer. i.e. the bp has not been linked into the vnode or
439 pbgetvp(struct vnode *vp, struct buf *bp)
442 KASSERT(bp->b_vp == NULL, ("pbgetvp: not free"));
443 KASSERT(bp->b_bufobj == NULL, ("pbgetvp: not free (bufobj)"));
446 bp->b_flags |= B_PAGING;
447 bp->b_bufobj = &vp->v_bufobj;
451 * Associate a p-buffer with a vnode.
453 * Also sets B_PAGING flag to indicate that vnode is not fully associated
454 * with the buffer. i.e. the bp has not been linked into the vnode or
458 pbgetbo(struct bufobj *bo, struct buf *bp)
461 KASSERT(bp->b_vp == NULL, ("pbgetbo: not free (vnode)"));
462 KASSERT(bp->b_bufobj == NULL, ("pbgetbo: not free (bufobj)"));
464 bp->b_flags |= B_PAGING;
469 * Disassociate a p-buffer from a vnode.
472 pbrelvp(struct buf *bp)
475 KASSERT(bp->b_vp != NULL, ("pbrelvp: NULL"));
476 KASSERT(bp->b_bufobj != NULL, ("pbrelvp: NULL bufobj"));
477 KASSERT((bp->b_xflags & (BX_VNDIRTY | BX_VNCLEAN)) == 0,
478 ("pbrelvp: pager buf on vnode list."));
482 bp->b_flags &= ~B_PAGING;
486 * Disassociate a p-buffer from a bufobj.
489 pbrelbo(struct buf *bp)
492 KASSERT(bp->b_vp == NULL, ("pbrelbo: vnode"));
493 KASSERT(bp->b_bufobj != NULL, ("pbrelbo: NULL bufobj"));
494 KASSERT((bp->b_xflags & (BX_VNDIRTY | BX_VNCLEAN)) == 0,
495 ("pbrelbo: pager buf on vnode list."));
498 bp->b_flags &= ~B_PAGING;