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. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * from: @(#)vm_pager.c 8.6 (Berkeley) 1/12/94
35 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
36 * All rights reserved.
38 * Authors: Avadis Tevanian, Jr., Michael Wayne Young
40 * Permission to use, copy, modify and distribute this software and
41 * its documentation is hereby granted, provided that both the copyright
42 * notice and this permission notice appear in all copies of the
43 * software, derivative works or modified versions, and any portions
44 * thereof, and that both notices appear in supporting documentation.
46 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
47 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
48 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
50 * Carnegie Mellon requests users of this software to return to
52 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
53 * School of Computer Science
54 * Carnegie Mellon University
55 * Pittsburgh PA 15213-3890
57 * any improvements or extensions that they make and grant Carnegie the
58 * rights to redistribute these changes.
62 * Paging space routine stubs. Emulates a matchmaker-like interface
66 #include <sys/cdefs.h>
67 __FBSDID("$FreeBSD$");
69 #include <sys/param.h>
70 #include <sys/systm.h>
71 #include <sys/kernel.h>
72 #include <sys/vnode.h>
75 #include <sys/ucred.h>
76 #include <sys/malloc.h>
77 #include <sys/rwlock.h>
80 #include <vm/vm_param.h>
81 #include <vm/vm_kern.h>
82 #include <vm/vm_object.h>
83 #include <vm/vm_page.h>
84 #include <vm/vm_pager.h>
85 #include <vm/vm_extern.h>
87 int cluster_pbuf_freecnt = -1; /* unlimited to begin with */
91 static int dead_pager_getpages(vm_object_t, vm_page_t *, int, int *, int *);
92 static vm_object_t dead_pager_alloc(void *, vm_ooffset_t, vm_prot_t,
93 vm_ooffset_t, struct ucred *);
94 static void dead_pager_putpages(vm_object_t, vm_page_t *, int, int, int *);
95 static boolean_t dead_pager_haspage(vm_object_t, vm_pindex_t, int *, int *);
96 static void dead_pager_dealloc(vm_object_t);
99 dead_pager_getpages(vm_object_t obj, vm_page_t *ma, int count, int *rbehind,
103 return (VM_PAGER_FAIL);
107 dead_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
108 vm_ooffset_t off, struct ucred *cred)
115 dead_pager_putpages(vm_object_t object, vm_page_t *m, int count,
116 int flags, int *rtvals)
120 for (i = 0; i < count; i++)
121 rtvals[i] = VM_PAGER_AGAIN;
125 dead_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *prev, int *next)
136 dead_pager_dealloc(vm_object_t object)
141 static struct pagerops deadpagerops = {
142 .pgo_alloc = dead_pager_alloc,
143 .pgo_dealloc = dead_pager_dealloc,
144 .pgo_getpages = dead_pager_getpages,
145 .pgo_putpages = dead_pager_putpages,
146 .pgo_haspage = dead_pager_haspage,
149 struct pagerops *pagertab[] = {
150 &defaultpagerops, /* OBJT_DEFAULT */
151 &swappagerops, /* OBJT_SWAP */
152 &vnodepagerops, /* OBJT_VNODE */
153 &devicepagerops, /* OBJT_DEVICE */
154 &physpagerops, /* OBJT_PHYS */
155 &deadpagerops, /* OBJT_DEAD */
156 &sgpagerops, /* OBJT_SG */
157 &mgtdevicepagerops, /* OBJT_MGTDEVICE */
161 * Kernel address space for mapping pages.
162 * Used by pagers where KVAs are needed for IO.
164 * XXX needs to be large enough to support the number of pending async
165 * cleaning requests (NPENDINGIO == 64) * the maximum swap cluster size
166 * (MAXPHYS == 64k) if you want to get the most efficiency.
168 struct mtx_padalign __exclusive_cache_line pbuf_mtx;
169 static TAILQ_HEAD(swqueue, buf) bswlist;
170 static int bswneeded;
171 vm_offset_t swapbkva; /* swap buffers kva */
176 struct pagerops **pgops;
178 TAILQ_INIT(&bswlist);
180 * Initialize known pagers
182 for (pgops = pagertab; pgops < &pagertab[nitems(pagertab)]; pgops++)
183 if ((*pgops)->pgo_init != NULL)
184 (*(*pgops)->pgo_init)();
188 vm_pager_bufferinit(void)
193 mtx_init(&pbuf_mtx, "pbuf mutex", NULL, MTX_DEF);
196 * Now set up swap and physical I/O buffer headers.
198 for (i = 0; i < nswbuf; i++, bp++) {
199 TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist);
201 LIST_INIT(&bp->b_dep);
202 bp->b_rcred = bp->b_wcred = NOCRED;
206 cluster_pbuf_freecnt = nswbuf / 2;
207 vnode_pbuf_freecnt = nswbuf / 2 + 1;
208 vnode_async_pbuf_freecnt = nswbuf / 2;
212 * Allocate an instance of a pager of the given type.
213 * Size, protection and offset parameters are passed in for pagers that
214 * need to perform page-level validation (e.g. the device pager).
217 vm_pager_allocate(objtype_t type, void *handle, vm_ooffset_t size,
218 vm_prot_t prot, vm_ooffset_t off, struct ucred *cred)
221 struct pagerops *ops;
223 ops = pagertab[type];
225 ret = (*ops->pgo_alloc)(handle, size, prot, off, cred);
232 * The object must be locked.
235 vm_pager_deallocate(vm_object_t object)
238 VM_OBJECT_ASSERT_WLOCKED(object);
239 (*pagertab[object->type]->pgo_dealloc) (object);
243 vm_pager_assert_in(vm_object_t object, vm_page_t *m, int count)
247 VM_OBJECT_ASSERT_WLOCKED(object);
248 KASSERT(count > 0, ("%s: 0 count", __func__));
250 * All pages must be busied, not mapped, not fully valid,
251 * not dirty and belong to the proper object.
253 for (int i = 0 ; i < count; i++) {
254 if (m[i] == bogus_page)
256 vm_page_assert_xbusied(m[i]);
257 KASSERT(!pmap_page_is_mapped(m[i]),
258 ("%s: page %p is mapped", __func__, m[i]));
259 KASSERT(m[i]->valid != VM_PAGE_BITS_ALL,
260 ("%s: request for a valid page %p", __func__, m[i]));
261 KASSERT(m[i]->dirty == 0,
262 ("%s: page %p is dirty", __func__, m[i]));
263 KASSERT(m[i]->object == object,
264 ("%s: wrong object %p/%p", __func__, object, m[i]->object));
270 * Page in the pages for the object using its associated pager.
271 * The requested page must be fully valid on successful return.
274 vm_pager_get_pages(vm_object_t object, vm_page_t *m, int count, int *rbehind,
278 vm_pindex_t pindex = m[0]->pindex;
282 vm_pager_assert_in(object, m, count);
284 r = (*pagertab[object->type]->pgo_getpages)(object, m, count, rbehind,
286 if (r != VM_PAGER_OK)
289 for (int i = 0; i < count; i++) {
291 * If pager has replaced a page, assert that it had
294 KASSERT(m[i] == vm_page_lookup(object, pindex++),
295 ("%s: mismatch page %p pindex %ju", __func__,
296 m[i], (uintmax_t )pindex - 1));
298 * Zero out partially filled data.
300 if (m[i]->valid != VM_PAGE_BITS_ALL)
301 vm_page_zero_invalid(m[i], TRUE);
303 return (VM_PAGER_OK);
307 vm_pager_get_pages_async(vm_object_t object, vm_page_t *m, int count,
308 int *rbehind, int *rahead, pgo_getpages_iodone_t iodone, void *arg)
311 vm_pager_assert_in(object, m, count);
313 return ((*pagertab[object->type]->pgo_getpages_async)(object, m,
314 count, rbehind, rahead, iodone, arg));
318 * vm_pager_put_pages() - inline, see vm/vm_pager.h
319 * vm_pager_has_page() - inline, see vm/vm_pager.h
323 * Search the specified pager object list for an object with the
324 * specified handle. If an object with the specified handle is found,
325 * increase its reference count and return it. Otherwise, return NULL.
327 * The pager object list must be locked.
330 vm_pager_object_lookup(struct pagerlst *pg_list, void *handle)
334 TAILQ_FOREACH(object, pg_list, pager_object_list) {
335 if (object->handle == handle) {
336 VM_OBJECT_WLOCK(object);
337 if ((object->flags & OBJ_DEAD) == 0) {
338 vm_object_reference_locked(object);
339 VM_OBJECT_WUNLOCK(object);
342 VM_OBJECT_WUNLOCK(object);
349 * initialize a physical buffer
353 * XXX This probably belongs in vfs_bio.c
356 initpbuf(struct buf *bp)
359 KASSERT(bp->b_bufobj == NULL, ("initpbuf with bufobj"));
360 KASSERT(bp->b_vp == NULL, ("initpbuf with vp"));
361 bp->b_rcred = NOCRED;
362 bp->b_wcred = NOCRED;
363 bp->b_qindex = 0; /* On no queue (QUEUE_NONE) */
364 bp->b_kvabase = (caddr_t)(MAXPHYS * (bp - swbuf)) + swapbkva;
365 bp->b_data = bp->b_kvabase;
366 bp->b_kvasize = MAXPHYS;
372 BUF_LOCK(bp, LK_EXCLUSIVE, NULL);
373 buf_track(bp, __func__);
377 * allocate a physical buffer
379 * There are a limited number (nswbuf) of physical buffers. We need
380 * to make sure that no single subsystem is able to hog all of them,
381 * so each subsystem implements a counter which is typically initialized
382 * to 1/2 nswbuf. getpbuf() decrements this counter in allocation and
383 * increments it on release, and blocks if the counter hits zero. A
384 * subsystem may initialize the counter to -1 to disable the feature,
385 * but it must still be sure to match up all uses of getpbuf() with
386 * relpbuf() using the same variable.
388 * NOTE: pfreecnt can be NULL, but this 'feature' will be removed
389 * relatively soon when the rest of the subsystems get smart about it. XXX
392 getpbuf(int *pfreecnt)
398 if (pfreecnt != NULL) {
399 while (*pfreecnt == 0) {
400 msleep(pfreecnt, &pbuf_mtx, PVM, "wswbuf0", 0);
404 /* get a bp from the swap buffer header pool */
405 if ((bp = TAILQ_FIRST(&bswlist)) != NULL)
409 msleep(&bswneeded, &pbuf_mtx, PVM, "wswbuf1", 0);
410 /* loop in case someone else grabbed one */
412 TAILQ_REMOVE(&bswlist, bp, b_freelist);
415 mtx_unlock(&pbuf_mtx);
421 * allocate a physical buffer, if one is available.
423 * Note that there is no NULL hack here - all subsystems using this
424 * call understand how to use pfreecnt.
427 trypbuf(int *pfreecnt)
432 if (*pfreecnt == 0 || (bp = TAILQ_FIRST(&bswlist)) == NULL) {
433 mtx_unlock(&pbuf_mtx);
436 TAILQ_REMOVE(&bswlist, bp, b_freelist);
438 mtx_unlock(&pbuf_mtx);
444 * release a physical buffer
446 * NOTE: pfreecnt can be NULL, but this 'feature' will be removed
447 * relatively soon when the rest of the subsystems get smart about it. XXX
450 relpbuf(struct buf *bp, int *pfreecnt)
453 if (bp->b_rcred != NOCRED) {
455 bp->b_rcred = NOCRED;
457 if (bp->b_wcred != NOCRED) {
459 bp->b_wcred = NOCRED;
462 KASSERT(bp->b_vp == NULL, ("relpbuf with vp"));
463 KASSERT(bp->b_bufobj == NULL, ("relpbuf with bufobj"));
465 buf_track(bp, __func__);
469 TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist);
476 if (++*pfreecnt == 1)
479 mtx_unlock(&pbuf_mtx);
483 * Associate a p-buffer with a vnode.
485 * Also sets B_PAGING flag to indicate that vnode is not fully associated
486 * with the buffer. i.e. the bp has not been linked into the vnode or
490 pbgetvp(struct vnode *vp, struct buf *bp)
493 KASSERT(bp->b_vp == NULL, ("pbgetvp: not free"));
494 KASSERT(bp->b_bufobj == NULL, ("pbgetvp: not free (bufobj)"));
497 bp->b_flags |= B_PAGING;
498 bp->b_bufobj = &vp->v_bufobj;
502 * Associate a p-buffer with a vnode.
504 * Also sets B_PAGING flag to indicate that vnode is not fully associated
505 * with the buffer. i.e. the bp has not been linked into the vnode or
509 pbgetbo(struct bufobj *bo, struct buf *bp)
512 KASSERT(bp->b_vp == NULL, ("pbgetbo: not free (vnode)"));
513 KASSERT(bp->b_bufobj == NULL, ("pbgetbo: not free (bufobj)"));
515 bp->b_flags |= B_PAGING;
520 * Disassociate a p-buffer from a vnode.
523 pbrelvp(struct buf *bp)
526 KASSERT(bp->b_vp != NULL, ("pbrelvp: NULL"));
527 KASSERT(bp->b_bufobj != NULL, ("pbrelvp: NULL bufobj"));
528 KASSERT((bp->b_xflags & (BX_VNDIRTY | BX_VNCLEAN)) == 0,
529 ("pbrelvp: pager buf on vnode list."));
533 bp->b_flags &= ~B_PAGING;
537 * Disassociate a p-buffer from a bufobj.
540 pbrelbo(struct buf *bp)
543 KASSERT(bp->b_vp == NULL, ("pbrelbo: vnode"));
544 KASSERT(bp->b_bufobj != NULL, ("pbrelbo: NULL bufobj"));
545 KASSERT((bp->b_xflags & (BX_VNDIRTY | BX_VNCLEAN)) == 0,
546 ("pbrelbo: pager buf on vnode list."));
549 bp->b_flags &= ~B_PAGING;