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 * 4. 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>
79 #include <vm/vm_param.h>
80 #include <vm/vm_object.h>
81 #include <vm/vm_page.h>
82 #include <vm/vm_pager.h>
83 #include <vm/vm_extern.h>
85 int cluster_pbuf_freecnt = -1; /* unlimited to begin with */
87 static int dead_pager_getpages(vm_object_t, vm_page_t *, int, int);
88 static vm_object_t dead_pager_alloc(void *, vm_ooffset_t, vm_prot_t,
89 vm_ooffset_t, struct ucred *);
90 static void dead_pager_putpages(vm_object_t, vm_page_t *, int, int, int *);
91 static boolean_t dead_pager_haspage(vm_object_t, vm_pindex_t, int *, int *);
92 static void dead_pager_dealloc(vm_object_t);
95 dead_pager_getpages(obj, ma, count, req)
101 return VM_PAGER_FAIL;
105 dead_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
106 vm_ooffset_t off, struct ucred *cred)
112 dead_pager_putpages(object, m, count, flags, rtvals)
121 for (i = 0; i < count; i++) {
122 rtvals[i] = VM_PAGER_AGAIN;
127 dead_pager_haspage(object, pindex, prev, next)
141 dead_pager_dealloc(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 */
165 static const int npagers = sizeof(pagertab) / sizeof(pagertab[0]);
168 * Kernel address space for mapping pages.
169 * Used by pagers where KVAs are needed for IO.
171 * XXX needs to be large enough to support the number of pending async
172 * cleaning requests (NPENDINGIO == 64) * the maximum swap cluster size
173 * (MAXPHYS == 64k) if you want to get the most efficiency.
176 static int bswneeded;
177 static vm_offset_t swapbkva; /* swap buffers kva */
179 static TAILQ_HEAD(swqueue, buf) bswlist;
184 struct pagerops **pgops;
186 TAILQ_INIT(&bswlist);
188 * Initialize known pagers
190 for (pgops = pagertab; pgops < &pagertab[npagers]; pgops++)
191 if (pgops && ((*pgops)->pgo_init != NULL))
192 (*(*pgops)->pgo_init) ();
196 vm_pager_bufferinit()
201 mtx_init(&pbuf_mtx, "pbuf mutex", NULL, MTX_DEF);
204 * Now set up swap and physical I/O buffer headers.
206 for (i = 0; i < nswbuf; i++, bp++) {
207 TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist);
209 LIST_INIT(&bp->b_dep);
210 bp->b_rcred = bp->b_wcred = NOCRED;
214 cluster_pbuf_freecnt = nswbuf / 2;
215 vnode_pbuf_freecnt = nswbuf / 2 + 1;
217 swapbkva = kmem_alloc_nofault(pager_map, nswbuf * MAXPHYS);
219 panic("Not enough pager_map VM space for physical buffers");
223 * Allocate an instance of a pager of the given type.
224 * Size, protection and offset parameters are passed in for pagers that
225 * need to perform page-level validation (e.g. the device pager).
228 vm_pager_allocate(objtype_t type, void *handle, vm_ooffset_t size,
229 vm_prot_t prot, vm_ooffset_t off, struct ucred *cred)
232 struct pagerops *ops;
234 ops = pagertab[type];
236 ret = (*ops->pgo_alloc) (handle, size, prot, off, cred);
243 * The object must be locked.
246 vm_pager_deallocate(object)
250 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
251 (*pagertab[object->type]->pgo_dealloc) (object);
255 * vm_pager_get_pages() - inline, see vm/vm_pager.h
256 * vm_pager_put_pages() - inline, see vm/vm_pager.h
257 * vm_pager_has_page() - inline, see vm/vm_pager.h
261 * Search the specified pager object list for an object with the
262 * specified handle. If an object with the specified handle is found,
263 * increase its reference count and return it. Otherwise, return NULL.
265 * The pager object list must be locked.
268 vm_pager_object_lookup(struct pagerlst *pg_list, void *handle)
272 TAILQ_FOREACH(object, pg_list, pager_object_list) {
273 VM_OBJECT_LOCK(object);
274 if (object->handle == handle &&
275 (object->flags & OBJ_DEAD) == 0) {
276 vm_object_reference_locked(object);
277 VM_OBJECT_UNLOCK(object);
280 VM_OBJECT_UNLOCK(object);
286 * initialize a physical buffer
290 * XXX This probably belongs in vfs_bio.c
293 initpbuf(struct buf *bp)
295 KASSERT(bp->b_bufobj == NULL, ("initpbuf with bufobj"));
296 KASSERT(bp->b_vp == NULL, ("initpbuf with vp"));
297 bp->b_rcred = NOCRED;
298 bp->b_wcred = NOCRED;
299 bp->b_qindex = 0; /* On no queue (QUEUE_NONE) */
300 bp->b_saveaddr = (caddr_t) (MAXPHYS * (bp - swbuf)) + swapbkva;
301 bp->b_data = bp->b_saveaddr;
302 bp->b_kvabase = bp->b_saveaddr;
303 bp->b_kvasize = MAXPHYS;
309 BUF_LOCK(bp, LK_EXCLUSIVE, NULL);
313 * allocate a physical buffer
315 * There are a limited number (nswbuf) of physical buffers. We need
316 * to make sure that no single subsystem is able to hog all of them,
317 * so each subsystem implements a counter which is typically initialized
318 * to 1/2 nswbuf. getpbuf() decrements this counter in allocation and
319 * increments it on release, and blocks if the counter hits zero. A
320 * subsystem may initialize the counter to -1 to disable the feature,
321 * but it must still be sure to match up all uses of getpbuf() with
322 * relpbuf() using the same variable.
324 * NOTE: pfreecnt can be NULL, but this 'feature' will be removed
325 * relatively soon when the rest of the subsystems get smart about it. XXX
328 getpbuf(int *pfreecnt)
336 while (*pfreecnt == 0) {
337 msleep(pfreecnt, &pbuf_mtx, PVM, "wswbuf0", 0);
341 /* get a bp from the swap buffer header pool */
342 if ((bp = TAILQ_FIRST(&bswlist)) != NULL)
346 msleep(&bswneeded, &pbuf_mtx, PVM, "wswbuf1", 0);
347 /* loop in case someone else grabbed one */
349 TAILQ_REMOVE(&bswlist, bp, b_freelist);
352 mtx_unlock(&pbuf_mtx);
359 * allocate a physical buffer, if one is available.
361 * Note that there is no NULL hack here - all subsystems using this
362 * call understand how to use pfreecnt.
365 trypbuf(int *pfreecnt)
370 if (*pfreecnt == 0 || (bp = TAILQ_FIRST(&bswlist)) == NULL) {
371 mtx_unlock(&pbuf_mtx);
374 TAILQ_REMOVE(&bswlist, bp, b_freelist);
378 mtx_unlock(&pbuf_mtx);
386 * release a physical buffer
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 relpbuf(struct buf *bp, int *pfreecnt)
395 if (bp->b_rcred != NOCRED) {
397 bp->b_rcred = NOCRED;
399 if (bp->b_wcred != NOCRED) {
401 bp->b_wcred = NOCRED;
404 KASSERT(bp->b_vp == NULL, ("relpbuf with vp"));
405 KASSERT(bp->b_bufobj == NULL, ("relpbuf with bufobj"));
410 TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist);
417 if (++*pfreecnt == 1)
420 mtx_unlock(&pbuf_mtx);
424 * Associate a p-buffer with a vnode.
426 * Also sets B_PAGING flag to indicate that vnode is not fully associated
427 * with the buffer. i.e. the bp has not been linked into the vnode or
431 pbgetvp(struct vnode *vp, struct buf *bp)
434 KASSERT(bp->b_vp == NULL, ("pbgetvp: not free"));
435 KASSERT(bp->b_bufobj == NULL, ("pbgetvp: not free (bufobj)"));
438 bp->b_flags |= B_PAGING;
439 bp->b_bufobj = &vp->v_bufobj;
443 * Associate a p-buffer with a vnode.
445 * Also sets B_PAGING flag to indicate that vnode is not fully associated
446 * with the buffer. i.e. the bp has not been linked into the vnode or
450 pbgetbo(struct bufobj *bo, struct buf *bp)
453 KASSERT(bp->b_vp == NULL, ("pbgetbo: not free (vnode)"));
454 KASSERT(bp->b_bufobj == NULL, ("pbgetbo: not free (bufobj)"));
456 bp->b_flags |= B_PAGING;
461 * Disassociate a p-buffer from a vnode.
464 pbrelvp(struct buf *bp)
467 KASSERT(bp->b_vp != NULL, ("pbrelvp: NULL"));
468 KASSERT(bp->b_bufobj != NULL, ("pbrelvp: NULL bufobj"));
471 BO_LOCK(bp->b_bufobj);
472 if (TAILQ_NEXT(bp, b_bobufs) != NULL) {
474 "relpbuf(): b_vp was probably reassignbuf()d %p %x",
479 BO_UNLOCK(bp->b_bufobj);
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"));
496 BO_LOCK(bp->b_bufobj);
497 if (TAILQ_NEXT(bp, b_bobufs) != NULL) {
499 "relpbuf(): b_vp was probably reassignbuf()d %p %x",
504 BO_UNLOCK(bp->b_bufobj);
506 bp->b_flags &= ~B_PAGING;