xref: /freebsd/sys/vm/vnode_pager.c (revision 33b77e2decd50e53798014b70bf7ca3bdc4c0c7e)
1 /*
2  * Copyright (c) 1990 University of Utah.
3  * Copyright (c) 1991 The Regents of the University of California.
4  * All rights reserved.
5  * Copyright (c) 1993, 1994 John S. Dyson
6  * Copyright (c) 1995, David Greenman
7  *
8  * This code is derived from software contributed to Berkeley by
9  * the Systems Programming Group of the University of Utah Computer
10  * Science Department.
11  *
12  * Redistribution and use in source and binary forms, with or without
13  * modification, are permitted provided that the following conditions
14  * are met:
15  * 1. Redistributions of source code must retain the above copyright
16  *    notice, this list of conditions and the following disclaimer.
17  * 2. Redistributions in binary form must reproduce the above copyright
18  *    notice, this list of conditions and the following disclaimer in the
19  *    documentation and/or other materials provided with the distribution.
20  * 3. All advertising materials mentioning features or use of this software
21  *    must display the following acknowledgement:
22  *	This product includes software developed by the University of
23  *	California, Berkeley and its contributors.
24  * 4. Neither the name of the University nor the names of its contributors
25  *    may be used to endorse or promote products derived from this software
26  *    without specific prior written permission.
27  *
28  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
29  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
30  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
31  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
32  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
33  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
34  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
35  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
36  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
37  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
38  * SUCH DAMAGE.
39  *
40  *	from: @(#)vnode_pager.c	7.5 (Berkeley) 4/20/91
41  *	$Id: vnode_pager.c,v 1.78 1997/12/29 00:25:11 dyson Exp $
42  */
43 
44 /*
45  * Page to/from files (vnodes).
46  */
47 
48 /*
49  * TODO:
50  *	Implement VOP_GETPAGES/PUTPAGES interface for filesystems. Will
51  *	greatly re-simplify the vnode_pager.
52  */
53 
54 #include <sys/param.h>
55 #include <sys/systm.h>
56 #include <sys/proc.h>
57 #include <sys/vnode.h>
58 #include <sys/mount.h>
59 #include <sys/buf.h>
60 #include <sys/vmmeter.h>
61 
62 #include <vm/vm.h>
63 #include <vm/vm_prot.h>
64 #include <vm/vm_object.h>
65 #include <vm/vm_page.h>
66 #include <vm/vm_pager.h>
67 #include <vm/vm_map.h>
68 #include <vm/vnode_pager.h>
69 #include <vm/vm_extern.h>
70 
71 static vm_offset_t vnode_pager_addr __P((struct vnode *vp, vm_ooffset_t address,
72 					 int *run));
73 static void vnode_pager_iodone __P((struct buf *bp));
74 static int vnode_pager_input_smlfs __P((vm_object_t object, vm_page_t m));
75 static int vnode_pager_input_old __P((vm_object_t object, vm_page_t m));
76 static void vnode_pager_dealloc __P((vm_object_t));
77 static int vnode_pager_getpages __P((vm_object_t, vm_page_t *, int, int));
78 static int vnode_pager_putpages __P((vm_object_t, vm_page_t *, int, boolean_t, int *));
79 static boolean_t vnode_pager_haspage __P((vm_object_t, vm_pindex_t, int *, int *));
80 
81 struct pagerops vnodepagerops = {
82 	NULL,
83 	vnode_pager_alloc,
84 	vnode_pager_dealloc,
85 	vnode_pager_getpages,
86 	vnode_pager_putpages,
87 	vnode_pager_haspage,
88 	NULL
89 };
90 
91 static int vnode_pager_leaf_getpages __P((vm_object_t object, vm_page_t *m,
92 					  int count, int reqpage));
93 static int vnode_pager_leaf_putpages __P((vm_object_t object, vm_page_t *m,
94 					  int count, boolean_t sync,
95 					  int *rtvals));
96 
97 /*
98  * Allocate (or lookup) pager for a vnode.
99  * Handle is a vnode pointer.
100  */
101 vm_object_t
102 vnode_pager_alloc(void *handle, vm_size_t size, vm_prot_t prot,
103 		  vm_ooffset_t offset)
104 {
105 	vm_object_t object;
106 	struct vnode *vp;
107 
108 	/*
109 	 * Pageout to vnode, no can do yet.
110 	 */
111 	if (handle == NULL)
112 		return (NULL);
113 
114 	vp = (struct vnode *) handle;
115 
116 	/*
117 	 * Prevent race condition when allocating the object. This
118 	 * can happen with NFS vnodes since the nfsnode isn't locked.
119 	 */
120 	while (vp->v_flag & VOLOCK) {
121 		vp->v_flag |= VOWANT;
122 		tsleep(vp, PVM, "vnpobj", 0);
123 	}
124 	vp->v_flag |= VOLOCK;
125 
126 	/*
127 	 * If the object is being terminated, wait for it to
128 	 * go away.
129 	 */
130 	while (((object = vp->v_object) != NULL) &&
131 		(object->flags & OBJ_DEAD)) {
132 		tsleep(object, PVM, "vadead", 0);
133 	}
134 
135 	if (vp->v_usecount == 0)
136 		panic("vnode_pager_alloc: no vnode reference");
137 
138 	if (object == NULL) {
139 		/*
140 		 * And an object of the appropriate size
141 		 */
142 		object = vm_object_allocate(OBJT_VNODE, size);
143 		object->flags = 0;
144 
145 		object->un_pager.vnp.vnp_size = (vm_ooffset_t) size * PAGE_SIZE;
146 
147 		object->handle = handle;
148 		vp->v_object = object;
149 		vp->v_usecount++;
150 	} else {
151 		object->ref_count++;
152 		vp->v_usecount++;
153 	}
154 
155 	vp->v_flag &= ~VOLOCK;
156 	if (vp->v_flag & VOWANT) {
157 		vp->v_flag &= ~VOWANT;
158 		wakeup(vp);
159 	}
160 	return (object);
161 }
162 
163 static void
164 vnode_pager_dealloc(object)
165 	vm_object_t object;
166 {
167 	register struct vnode *vp = object->handle;
168 
169 	if (vp == NULL)
170 		panic("vnode_pager_dealloc: pager already dealloced");
171 
172 	if (object->paging_in_progress) {
173 		int s = splbio();
174 		while (object->paging_in_progress) {
175 			object->flags |= OBJ_PIPWNT;
176 			tsleep(object, PVM, "vnpdea", 0);
177 		}
178 		splx(s);
179 	}
180 
181 	object->flags |= OBJ_DEAD;
182 	object->handle = NULL;
183 	object->type = OBJT_DEFAULT;
184 	vp->v_object = NULL;
185 	vp->v_flag &= ~(VTEXT|VOBJBUF);
186 }
187 
188 static boolean_t
189 vnode_pager_haspage(object, pindex, before, after)
190 	vm_object_t object;
191 	vm_pindex_t pindex;
192 	int *before;
193 	int *after;
194 {
195 	struct vnode *vp = object->handle;
196 	daddr_t bn;
197 	int err;
198 	daddr_t reqblock;
199 	int poff;
200 	int bsize;
201 	int pagesperblock, blocksperpage;
202 
203 	/*
204 	 * If filesystem no longer mounted or offset beyond end of file we do
205 	 * not have the page.
206 	 */
207 	if ((vp->v_mount == NULL) ||
208 		(IDX_TO_OFF(pindex) >= object->un_pager.vnp.vnp_size))
209 		return FALSE;
210 
211 	bsize = vp->v_mount->mnt_stat.f_iosize;
212 	pagesperblock = bsize / PAGE_SIZE;
213 	blocksperpage = 0;
214 	if (pagesperblock > 0) {
215 		reqblock = pindex / pagesperblock;
216 	} else {
217 		blocksperpage = (PAGE_SIZE / bsize);
218 		reqblock = pindex * blocksperpage;
219 	}
220 	err = VOP_BMAP(vp, reqblock, (struct vnode **) 0, &bn,
221 		after, before);
222 	if (err)
223 		return TRUE;
224 	if ( bn == -1)
225 		return FALSE;
226 	if (pagesperblock > 0) {
227 		poff = pindex - (reqblock * pagesperblock);
228 		if (before) {
229 			*before *= pagesperblock;
230 			*before += poff;
231 		}
232 		if (after) {
233 			int numafter;
234 			*after *= pagesperblock;
235 			numafter = pagesperblock - (poff + 1);
236 			if (IDX_TO_OFF(pindex + numafter) > object->un_pager.vnp.vnp_size) {
237 				numafter = OFF_TO_IDX((object->un_pager.vnp.vnp_size - IDX_TO_OFF(pindex)));
238 			}
239 			*after += numafter;
240 		}
241 	} else {
242 		if (before) {
243 			*before /= blocksperpage;
244 		}
245 
246 		if (after) {
247 			*after /= blocksperpage;
248 		}
249 	}
250 	return TRUE;
251 }
252 
253 /*
254  * Lets the VM system know about a change in size for a file.
255  * We adjust our own internal size and flush any cached pages in
256  * the associated object that are affected by the size change.
257  *
258  * Note: this routine may be invoked as a result of a pager put
259  * operation (possibly at object termination time), so we must be careful.
260  */
261 void
262 vnode_pager_setsize(vp, nsize)
263 	struct vnode *vp;
264 	vm_ooffset_t nsize;
265 {
266 	vm_object_t object = vp->v_object;
267 
268 	if (object == NULL)
269 		return;
270 
271 	/*
272 	 * Hasn't changed size
273 	 */
274 	if (nsize == object->un_pager.vnp.vnp_size)
275 		return;
276 
277 	/*
278 	 * File has shrunk. Toss any cached pages beyond the new EOF.
279 	 */
280 	if (nsize < object->un_pager.vnp.vnp_size) {
281 		vm_ooffset_t nsizerounded;
282 		nsizerounded = IDX_TO_OFF(OFF_TO_IDX(nsize + PAGE_MASK));
283 		if (nsizerounded < object->un_pager.vnp.vnp_size) {
284 			vm_pindex_t st, end;
285 			st = OFF_TO_IDX(nsize + PAGE_MASK);
286 			end = OFF_TO_IDX(object->un_pager.vnp.vnp_size);
287 
288 			vm_freeze_copyopts(object, OFF_TO_IDX(nsize), object->size);
289 			vm_object_page_remove(object, st, end, FALSE);
290 		}
291 		/*
292 		 * this gets rid of garbage at the end of a page that is now
293 		 * only partially backed by the vnode...
294 		 */
295 		if (nsize & PAGE_MASK) {
296 			vm_offset_t kva;
297 			vm_page_t m;
298 
299 			m = vm_page_lookup(object, OFF_TO_IDX(nsize));
300 			if (m) {
301 				kva = vm_pager_map_page(m);
302 				bzero((caddr_t) kva + (nsize & PAGE_MASK),
303 				    (int) (round_page(nsize) - nsize));
304 				vm_pager_unmap_page(kva);
305 			}
306 		}
307 	}
308 	object->un_pager.vnp.vnp_size = nsize;
309 	object->size = OFF_TO_IDX(nsize + PAGE_MASK);
310 }
311 
312 void
313 vnode_pager_freepage(m)
314 	vm_page_t m;
315 {
316 	PAGE_WAKEUP(m);
317 	vm_page_free(m);
318 }
319 
320 /*
321  * calculate the linear (byte) disk address of specified virtual
322  * file address
323  */
324 static vm_offset_t
325 vnode_pager_addr(vp, address, run)
326 	struct vnode *vp;
327 	vm_ooffset_t address;
328 	int *run;
329 {
330 	int rtaddress;
331 	int bsize;
332 	daddr_t block;
333 	struct vnode *rtvp;
334 	int err;
335 	daddr_t vblock;
336 	int voffset;
337 
338 	if ((int) address < 0)
339 		return -1;
340 
341 	if (vp->v_mount == NULL)
342 		return -1;
343 
344 	bsize = vp->v_mount->mnt_stat.f_iosize;
345 	vblock = address / bsize;
346 	voffset = address % bsize;
347 
348 	err = VOP_BMAP(vp, vblock, &rtvp, &block, run, NULL);
349 
350 	if (err || (block == -1))
351 		rtaddress = -1;
352 	else {
353 		rtaddress = block + voffset / DEV_BSIZE;
354 		if( run) {
355 			*run += 1;
356 			*run *= bsize/PAGE_SIZE;
357 			*run -= voffset/PAGE_SIZE;
358 		}
359 	}
360 
361 	return rtaddress;
362 }
363 
364 /*
365  * interrupt routine for I/O completion
366  */
367 static void
368 vnode_pager_iodone(bp)
369 	struct buf *bp;
370 {
371 	bp->b_flags |= B_DONE;
372 	wakeup(bp);
373 }
374 
375 /*
376  * small block file system vnode pager input
377  */
378 static int
379 vnode_pager_input_smlfs(object, m)
380 	vm_object_t object;
381 	vm_page_t m;
382 {
383 	int i;
384 	int s;
385 	struct vnode *dp, *vp;
386 	struct buf *bp;
387 	vm_offset_t kva;
388 	int fileaddr;
389 	vm_offset_t bsize;
390 	int error = 0;
391 
392 	vp = object->handle;
393 	if (vp->v_mount == NULL)
394 		return VM_PAGER_BAD;
395 
396 	bsize = vp->v_mount->mnt_stat.f_iosize;
397 
398 
399 	VOP_BMAP(vp, 0, &dp, 0, NULL, NULL);
400 
401 	kva = vm_pager_map_page(m);
402 
403 	for (i = 0; i < PAGE_SIZE / bsize; i++) {
404 
405 		if ((vm_page_bits(IDX_TO_OFF(m->pindex) + i * bsize, bsize) & m->valid))
406 			continue;
407 
408 		fileaddr = vnode_pager_addr(vp,
409 			IDX_TO_OFF(m->pindex) + i * bsize, (int *)0);
410 		if (fileaddr != -1) {
411 			bp = getpbuf();
412 
413 			/* build a minimal buffer header */
414 			bp->b_flags = B_BUSY | B_READ | B_CALL;
415 			bp->b_iodone = vnode_pager_iodone;
416 			bp->b_proc = curproc;
417 			bp->b_rcred = bp->b_wcred = bp->b_proc->p_ucred;
418 			if (bp->b_rcred != NOCRED)
419 				crhold(bp->b_rcred);
420 			if (bp->b_wcred != NOCRED)
421 				crhold(bp->b_wcred);
422 			bp->b_data = (caddr_t) kva + i * bsize;
423 			bp->b_blkno = fileaddr;
424 			pbgetvp(dp, bp);
425 			bp->b_bcount = bsize;
426 			bp->b_bufsize = bsize;
427 
428 			/* do the input */
429 			VOP_STRATEGY(bp);
430 
431 			/* we definitely need to be at splbio here */
432 
433 			s = splbio();
434 			while ((bp->b_flags & B_DONE) == 0) {
435 				tsleep(bp, PVM, "vnsrd", 0);
436 			}
437 			splx(s);
438 			if ((bp->b_flags & B_ERROR) != 0)
439 				error = EIO;
440 
441 			/*
442 			 * free the buffer header back to the swap buffer pool
443 			 */
444 			relpbuf(bp);
445 			if (error)
446 				break;
447 
448 			vm_page_set_validclean(m, (i * bsize) & PAGE_MASK, bsize);
449 		} else {
450 			vm_page_set_validclean(m, (i * bsize) & PAGE_MASK, bsize);
451 			bzero((caddr_t) kva + i * bsize, bsize);
452 		}
453 	}
454 	vm_pager_unmap_page(kva);
455 	pmap_clear_modify(VM_PAGE_TO_PHYS(m));
456 	m->flags &= ~PG_ZERO;
457 	if (error) {
458 		return VM_PAGER_ERROR;
459 	}
460 	return VM_PAGER_OK;
461 
462 }
463 
464 
465 /*
466  * old style vnode pager output routine
467  */
468 static int
469 vnode_pager_input_old(object, m)
470 	vm_object_t object;
471 	vm_page_t m;
472 {
473 	struct uio auio;
474 	struct iovec aiov;
475 	int error;
476 	int size;
477 	vm_offset_t kva;
478 
479 	error = 0;
480 
481 	/*
482 	 * Return failure if beyond current EOF
483 	 */
484 	if (IDX_TO_OFF(m->pindex) >= object->un_pager.vnp.vnp_size) {
485 		return VM_PAGER_BAD;
486 	} else {
487 		size = PAGE_SIZE;
488 		if (IDX_TO_OFF(m->pindex) + size > object->un_pager.vnp.vnp_size)
489 			size = object->un_pager.vnp.vnp_size - IDX_TO_OFF(m->pindex);
490 
491 		/*
492 		 * Allocate a kernel virtual address and initialize so that
493 		 * we can use VOP_READ/WRITE routines.
494 		 */
495 		kva = vm_pager_map_page(m);
496 
497 		aiov.iov_base = (caddr_t) kva;
498 		aiov.iov_len = size;
499 		auio.uio_iov = &aiov;
500 		auio.uio_iovcnt = 1;
501 		auio.uio_offset = IDX_TO_OFF(m->pindex);
502 		auio.uio_segflg = UIO_SYSSPACE;
503 		auio.uio_rw = UIO_READ;
504 		auio.uio_resid = size;
505 		auio.uio_procp = (struct proc *) 0;
506 
507 		error = VOP_READ(object->handle, &auio, 0, curproc->p_ucred);
508 		if (!error) {
509 			register int count = size - auio.uio_resid;
510 
511 			if (count == 0)
512 				error = EINVAL;
513 			else if (count != PAGE_SIZE)
514 				bzero((caddr_t) kva + count, PAGE_SIZE - count);
515 		}
516 		vm_pager_unmap_page(kva);
517 	}
518 	pmap_clear_modify(VM_PAGE_TO_PHYS(m));
519 	m->dirty = 0;
520 	m->flags &= ~PG_ZERO;
521 	return error ? VM_PAGER_ERROR : VM_PAGER_OK;
522 }
523 
524 /*
525  * generic vnode pager input routine
526  */
527 
528 static int
529 vnode_pager_getpages(object, m, count, reqpage)
530 	vm_object_t object;
531 	vm_page_t *m;
532 	int count;
533 	int reqpage;
534 {
535 	int rtval;
536 	struct vnode *vp;
537 
538 	vp = object->handle;
539 	rtval = VOP_GETPAGES(vp, m, count*PAGE_SIZE, reqpage, 0);
540 	if (rtval == EOPNOTSUPP)
541 		return vnode_pager_leaf_getpages(object, m, count, reqpage);
542 	else
543 		return rtval;
544 }
545 
546 static int
547 vnode_pager_leaf_getpages(object, m, count, reqpage)
548 	vm_object_t object;
549 	vm_page_t *m;
550 	int count;
551 	int reqpage;
552 {
553 	vm_offset_t kva;
554 	off_t foff;
555 	int i, size, bsize, first, firstaddr;
556 	struct vnode *dp, *vp;
557 	int runpg;
558 	int runend;
559 	struct buf *bp;
560 	int s;
561 	int error = 0;
562 
563 	vp = object->handle;
564 	if (vp->v_mount == NULL)
565 		return VM_PAGER_BAD;
566 
567 	bsize = vp->v_mount->mnt_stat.f_iosize;
568 
569 	/* get the UNDERLYING device for the file with VOP_BMAP() */
570 
571 	/*
572 	 * originally, we did not check for an error return value -- assuming
573 	 * an fs always has a bmap entry point -- that assumption is wrong!!!
574 	 */
575 	foff = IDX_TO_OFF(m[reqpage]->pindex);
576 
577 	/*
578 	 * if we can't bmap, use old VOP code
579 	 */
580 	if (VOP_BMAP(vp, 0, &dp, 0, NULL, NULL)) {
581 		for (i = 0; i < count; i++) {
582 			if (i != reqpage) {
583 				vnode_pager_freepage(m[i]);
584 			}
585 		}
586 		cnt.v_vnodein++;
587 		cnt.v_vnodepgsin++;
588 		return vnode_pager_input_old(object, m[reqpage]);
589 
590 		/*
591 		 * if the blocksize is smaller than a page size, then use
592 		 * special small filesystem code.  NFS sometimes has a small
593 		 * blocksize, but it can handle large reads itself.
594 		 */
595 	} else if ((PAGE_SIZE / bsize) > 1 &&
596 	    (vp->v_mount->mnt_stat.f_type != MOUNT_NFS)) {
597 
598 		for (i = 0; i < count; i++) {
599 			if (i != reqpage) {
600 				vnode_pager_freepage(m[i]);
601 			}
602 		}
603 		cnt.v_vnodein++;
604 		cnt.v_vnodepgsin++;
605 		return vnode_pager_input_smlfs(object, m[reqpage]);
606 	}
607 	/*
608 	 * if ANY DEV_BSIZE blocks are valid on a large filesystem block
609 	 * then, the entire page is valid --
610 	 * XXX no it isn't
611 	 */
612 
613 	if (m[reqpage]->valid != VM_PAGE_BITS_ALL)
614 	    m[reqpage]->valid = 0;
615 
616 	if (m[reqpage]->valid) {
617 		m[reqpage]->valid = VM_PAGE_BITS_ALL;
618 		for (i = 0; i < count; i++) {
619 			if (i != reqpage)
620 				vnode_pager_freepage(m[i]);
621 		}
622 		return VM_PAGER_OK;
623 	}
624 
625 	/*
626 	 * here on direct device I/O
627 	 */
628 
629 	firstaddr = -1;
630 	/*
631 	 * calculate the run that includes the required page
632 	 */
633 	for(first = 0, i = 0; i < count; i = runend) {
634 		firstaddr = vnode_pager_addr(vp,
635 			IDX_TO_OFF(m[i]->pindex), &runpg);
636 		if (firstaddr == -1) {
637 			if (i == reqpage && foff < object->un_pager.vnp.vnp_size) {
638 				panic("vnode_pager_getpages: unexpected missing page: firstaddr: %d, foff: %ld, vnp_size: %d",
639 			   	 firstaddr, foff, object->un_pager.vnp.vnp_size);
640 			}
641 			vnode_pager_freepage(m[i]);
642 			runend = i + 1;
643 			first = runend;
644 			continue;
645 		}
646 		runend = i + runpg;
647 		if (runend <= reqpage) {
648 			int j;
649 			for (j = i; j < runend; j++) {
650 				vnode_pager_freepage(m[j]);
651 			}
652 		} else {
653 			if (runpg < (count - first)) {
654 				for (i = first + runpg; i < count; i++)
655 					vnode_pager_freepage(m[i]);
656 				count = first + runpg;
657 			}
658 			break;
659 		}
660 		first = runend;
661 	}
662 
663 	/*
664 	 * the first and last page have been calculated now, move input pages
665 	 * to be zero based...
666 	 */
667 	if (first != 0) {
668 		for (i = first; i < count; i++) {
669 			m[i - first] = m[i];
670 		}
671 		count -= first;
672 		reqpage -= first;
673 	}
674 
675 	/*
676 	 * calculate the file virtual address for the transfer
677 	 */
678 	foff = IDX_TO_OFF(m[0]->pindex);
679 
680 	/*
681 	 * calculate the size of the transfer
682 	 */
683 	size = count * PAGE_SIZE;
684 	if ((foff + size) > object->un_pager.vnp.vnp_size)
685 		size = object->un_pager.vnp.vnp_size - foff;
686 
687 	/*
688 	 * round up physical size for real devices
689 	 */
690 	if (dp->v_type == VBLK || dp->v_type == VCHR)
691 		size = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
692 
693 	bp = getpbuf();
694 	kva = (vm_offset_t) bp->b_data;
695 
696 	/*
697 	 * and map the pages to be read into the kva
698 	 */
699 	pmap_qenter(kva, m, count);
700 
701 	/* build a minimal buffer header */
702 	bp->b_flags = B_BUSY | B_READ | B_CALL;
703 	bp->b_iodone = vnode_pager_iodone;
704 	/* B_PHYS is not set, but it is nice to fill this in */
705 	bp->b_proc = curproc;
706 	bp->b_rcred = bp->b_wcred = bp->b_proc->p_ucred;
707 	if (bp->b_rcred != NOCRED)
708 		crhold(bp->b_rcred);
709 	if (bp->b_wcred != NOCRED)
710 		crhold(bp->b_wcred);
711 	bp->b_blkno = firstaddr;
712 	pbgetvp(dp, bp);
713 	bp->b_bcount = size;
714 	bp->b_bufsize = size;
715 
716 	cnt.v_vnodein++;
717 	cnt.v_vnodepgsin += count;
718 
719 	/* do the input */
720 	VOP_STRATEGY(bp);
721 
722 	s = splbio();
723 	/* we definitely need to be at splbio here */
724 
725 	while ((bp->b_flags & B_DONE) == 0) {
726 		tsleep(bp, PVM, "vnread", 0);
727 	}
728 	splx(s);
729 	if ((bp->b_flags & B_ERROR) != 0)
730 		error = EIO;
731 
732 	if (!error) {
733 		if (size != count * PAGE_SIZE)
734 			bzero((caddr_t) kva + size, PAGE_SIZE * count - size);
735 	}
736 	pmap_qremove(kva, count);
737 
738 	/*
739 	 * free the buffer header back to the swap buffer pool
740 	 */
741 	relpbuf(bp);
742 
743 	for (i = 0; i < count; i++) {
744 		pmap_clear_modify(VM_PAGE_TO_PHYS(m[i]));
745 		m[i]->dirty = 0;
746 		m[i]->valid = VM_PAGE_BITS_ALL;
747 		m[i]->flags &= ~PG_ZERO;
748 		if (i != reqpage) {
749 
750 			/*
751 			 * whether or not to leave the page activated is up in
752 			 * the air, but we should put the page on a page queue
753 			 * somewhere. (it already is in the object). Result:
754 			 * It appears that emperical results show that
755 			 * deactivating pages is best.
756 			 */
757 
758 			/*
759 			 * just in case someone was asking for this page we
760 			 * now tell them that it is ok to use
761 			 */
762 			if (!error) {
763 				vm_page_deactivate(m[i]);
764 				PAGE_WAKEUP(m[i]);
765 			} else {
766 				vnode_pager_freepage(m[i]);
767 			}
768 		}
769 	}
770 	if (error) {
771 		printf("vnode_pager_getpages: I/O read error\n");
772 	}
773 	return (error ? VM_PAGER_ERROR : VM_PAGER_OK);
774 }
775 
776 static int
777 vnode_pager_putpages(object, m, count, sync, rtvals)
778 	vm_object_t object;
779 	vm_page_t *m;
780 	int count;
781 	boolean_t sync;
782 	int *rtvals;
783 {
784 	int rtval;
785 	struct vnode *vp;
786 
787 	vp = object->handle;
788 	rtval = VOP_PUTPAGES(vp, m, count*PAGE_SIZE, sync, rtvals, 0);
789 	if (rtval == EOPNOTSUPP)
790 		return vnode_pager_leaf_putpages(object, m, count, sync, rtvals);
791 	else
792 		return rtval;
793 }
794 
795 /*
796  * generic vnode pager output routine
797  */
798 static int
799 vnode_pager_leaf_putpages(object, m, count, sync, rtvals)
800 	vm_object_t object;
801 	vm_page_t *m;
802 	int count;
803 	boolean_t sync;
804 	int *rtvals;
805 {
806 	int i;
807 
808 	struct vnode *vp;
809 	int maxsize, ncount;
810 	vm_ooffset_t poffset;
811 	struct uio auio;
812 	struct iovec aiov;
813 	int error;
814 
815 	vp = object->handle;;
816 	for (i = 0; i < count; i++)
817 		rtvals[i] = VM_PAGER_AGAIN;
818 
819 	if ((int) m[0]->pindex < 0) {
820 		printf("vnode_pager_putpages: attempt to write meta-data!!! -- 0x%x(%x)\n", m[0]->pindex, m[0]->dirty);
821 		rtvals[0] = VM_PAGER_BAD;
822 		return VM_PAGER_BAD;
823 	}
824 
825 	maxsize = count * PAGE_SIZE;
826 	ncount = count;
827 
828 	poffset = IDX_TO_OFF(m[0]->pindex);
829 	if (maxsize + poffset > object->un_pager.vnp.vnp_size) {
830 		if (object->un_pager.vnp.vnp_size > poffset)
831 			maxsize = object->un_pager.vnp.vnp_size - poffset;
832 		else
833 			maxsize = 0;
834 		ncount = btoc(maxsize);
835 		if (ncount < count) {
836 			for (i = ncount; i < count; i++) {
837 				rtvals[i] = VM_PAGER_BAD;
838 			}
839 #ifdef BOGUS
840 			if (ncount == 0) {
841 				printf("vnode_pager_putpages: write past end of file: %d, %lu\n",
842 					poffset,
843 					(unsigned long) object->un_pager.vnp.vnp_size);
844 				return rtvals[0];
845 			}
846 #endif
847 		}
848 	}
849 
850 	for (i = 0; i < count; i++) {
851 		m[i]->busy++;
852 		m[i]->flags &= ~PG_BUSY;
853 	}
854 
855 	aiov.iov_base = (caddr_t) 0;
856 	aiov.iov_len = maxsize;
857 	auio.uio_iov = &aiov;
858 	auio.uio_iovcnt = 1;
859 	auio.uio_offset = poffset;
860 	auio.uio_segflg = UIO_NOCOPY;
861 	auio.uio_rw = UIO_WRITE;
862 	auio.uio_resid = maxsize;
863 	auio.uio_procp = (struct proc *) 0;
864 	error = VOP_WRITE(vp, &auio, IO_VMIO|(sync?IO_SYNC:0), curproc->p_ucred);
865 	cnt.v_vnodeout++;
866 	cnt.v_vnodepgsout += ncount;
867 
868 	if (error) {
869 		printf("vnode_pager_putpages: I/O error %d\n", error);
870 	}
871 	if (auio.uio_resid) {
872 		printf("vnode_pager_putpages: residual I/O %d at %ld\n",
873 			auio.uio_resid, m[0]->pindex);
874 	}
875 	for (i = 0; i < count; i++) {
876 		m[i]->busy--;
877 		if (i < ncount) {
878 			rtvals[i] = VM_PAGER_OK;
879 		}
880 		if ((m[i]->busy == 0) && (m[i]->flags & PG_WANTED))
881 			wakeup(m[i]);
882 	}
883 	return rtvals[0];
884 }
885 
886 struct vnode *
887 vnode_pager_lock(object)
888 	vm_object_t object;
889 {
890 	struct proc *p = curproc;	/* XXX */
891 
892 	for (; object != NULL; object = object->backing_object) {
893 		if (object->type != OBJT_VNODE)
894 			continue;
895 
896 		vn_lock(object->handle,
897 			LK_NOPAUSE | LK_SHARED | LK_RETRY | LK_CANRECURSE, p);
898 		return object->handle;
899 	}
900 	return NULL;
901 }
902