xref: /freebsd/sys/vm/vnode_pager.c (revision 609e0c94f2ea3e5e75ddf58a45ec23613265f2a6)
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 1.80 1998/01/17 09:17:02 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->handle = NULL;
182 	object->type = OBJT_DEFAULT;
183 	vp->v_object = NULL;
184 	vp->v_flag &= ~(VTEXT|VOBJBUF);
185 }
186 
187 static boolean_t
188 vnode_pager_haspage(object, pindex, before, after)
189 	vm_object_t object;
190 	vm_pindex_t pindex;
191 	int *before;
192 	int *after;
193 {
194 	struct vnode *vp = object->handle;
195 	daddr_t bn;
196 	int err;
197 	daddr_t reqblock;
198 	int poff;
199 	int bsize;
200 	int pagesperblock, blocksperpage;
201 
202 	if ((vp == NULL) || (vp->v_flag & VDOOMED))
203 		return FALSE;
204 
205 	/*
206 	 * If filesystem no longer mounted or offset beyond end of file we do
207 	 * not have the page.
208 	 */
209 	if ((vp->v_mount == NULL) ||
210 		(IDX_TO_OFF(pindex) >= object->un_pager.vnp.vnp_size))
211 		return FALSE;
212 
213 	bsize = vp->v_mount->mnt_stat.f_iosize;
214 	pagesperblock = bsize / PAGE_SIZE;
215 	blocksperpage = 0;
216 	if (pagesperblock > 0) {
217 		reqblock = pindex / pagesperblock;
218 	} else {
219 		blocksperpage = (PAGE_SIZE / bsize);
220 		reqblock = pindex * blocksperpage;
221 	}
222 	err = VOP_BMAP(vp, reqblock, (struct vnode **) 0, &bn,
223 		after, before);
224 	if (err)
225 		return TRUE;
226 	if ( bn == -1)
227 		return FALSE;
228 	if (pagesperblock > 0) {
229 		poff = pindex - (reqblock * pagesperblock);
230 		if (before) {
231 			*before *= pagesperblock;
232 			*before += poff;
233 		}
234 		if (after) {
235 			int numafter;
236 			*after *= pagesperblock;
237 			numafter = pagesperblock - (poff + 1);
238 			if (IDX_TO_OFF(pindex + numafter) > object->un_pager.vnp.vnp_size) {
239 				numafter = OFF_TO_IDX((object->un_pager.vnp.vnp_size - IDX_TO_OFF(pindex)));
240 			}
241 			*after += numafter;
242 		}
243 	} else {
244 		if (before) {
245 			*before /= blocksperpage;
246 		}
247 
248 		if (after) {
249 			*after /= blocksperpage;
250 		}
251 	}
252 	return TRUE;
253 }
254 
255 /*
256  * Lets the VM system know about a change in size for a file.
257  * We adjust our own internal size and flush any cached pages in
258  * the associated object that are affected by the size change.
259  *
260  * Note: this routine may be invoked as a result of a pager put
261  * operation (possibly at object termination time), so we must be careful.
262  */
263 void
264 vnode_pager_setsize(vp, nsize)
265 	struct vnode *vp;
266 	vm_ooffset_t nsize;
267 {
268 	vm_object_t object = vp->v_object;
269 
270 	if (object == NULL)
271 		return;
272 
273 	/*
274 	 * Hasn't changed size
275 	 */
276 	if (nsize == object->un_pager.vnp.vnp_size)
277 		return;
278 
279 	/*
280 	 * File has shrunk. Toss any cached pages beyond the new EOF.
281 	 */
282 	if (nsize < object->un_pager.vnp.vnp_size) {
283 		vm_ooffset_t nsizerounded;
284 		nsizerounded = IDX_TO_OFF(OFF_TO_IDX(nsize + PAGE_MASK));
285 		if (nsizerounded < object->un_pager.vnp.vnp_size) {
286 			vm_pindex_t st, end;
287 			st = OFF_TO_IDX(nsize + PAGE_MASK);
288 			end = OFF_TO_IDX(object->un_pager.vnp.vnp_size);
289 
290 			vm_freeze_copyopts(object, OFF_TO_IDX(nsize), object->size);
291 			vm_object_page_remove(object, st, end, FALSE);
292 		}
293 		/*
294 		 * this gets rid of garbage at the end of a page that is now
295 		 * only partially backed by the vnode...
296 		 */
297 		if (nsize & PAGE_MASK) {
298 			vm_offset_t kva;
299 			vm_page_t m;
300 
301 			m = vm_page_lookup(object, OFF_TO_IDX(nsize));
302 			if (m) {
303 				kva = vm_pager_map_page(m);
304 				bzero((caddr_t) kva + (nsize & PAGE_MASK),
305 				    (int) (round_page(nsize) - nsize));
306 				vm_pager_unmap_page(kva);
307 			}
308 		}
309 	}
310 	object->un_pager.vnp.vnp_size = nsize;
311 	object->size = OFF_TO_IDX(nsize + PAGE_MASK);
312 }
313 
314 void
315 vnode_pager_freepage(m)
316 	vm_page_t m;
317 {
318 	vm_page_free(m);
319 }
320 
321 /*
322  * calculate the linear (byte) disk address of specified virtual
323  * file address
324  */
325 static vm_offset_t
326 vnode_pager_addr(vp, address, run)
327 	struct vnode *vp;
328 	vm_ooffset_t address;
329 	int *run;
330 {
331 	int rtaddress;
332 	int bsize;
333 	daddr_t block;
334 	struct vnode *rtvp;
335 	int err;
336 	daddr_t vblock;
337 	int voffset;
338 
339 	if ((int) address < 0)
340 		return -1;
341 
342 	if (vp->v_mount == NULL)
343 		return -1;
344 
345 	bsize = vp->v_mount->mnt_stat.f_iosize;
346 	vblock = address / bsize;
347 	voffset = address % bsize;
348 
349 	err = VOP_BMAP(vp, vblock, &rtvp, &block, run, NULL);
350 
351 	if (err || (block == -1))
352 		rtaddress = -1;
353 	else {
354 		rtaddress = block + voffset / DEV_BSIZE;
355 		if( run) {
356 			*run += 1;
357 			*run *= bsize/PAGE_SIZE;
358 			*run -= voffset/PAGE_SIZE;
359 		}
360 	}
361 
362 	return rtaddress;
363 }
364 
365 /*
366  * interrupt routine for I/O completion
367  */
368 static void
369 vnode_pager_iodone(bp)
370 	struct buf *bp;
371 {
372 	bp->b_flags |= B_DONE;
373 	wakeup(bp);
374 }
375 
376 /*
377  * small block file system vnode pager input
378  */
379 static int
380 vnode_pager_input_smlfs(object, m)
381 	vm_object_t object;
382 	vm_page_t m;
383 {
384 	int i;
385 	int s;
386 	struct vnode *dp, *vp;
387 	struct buf *bp;
388 	vm_offset_t kva;
389 	int fileaddr;
390 	vm_offset_t bsize;
391 	int error = 0;
392 
393 	vp = object->handle;
394 	if (vp->v_mount == NULL)
395 		return VM_PAGER_BAD;
396 
397 	bsize = vp->v_mount->mnt_stat.f_iosize;
398 
399 
400 	VOP_BMAP(vp, 0, &dp, 0, NULL, NULL);
401 
402 	kva = vm_pager_map_page(m);
403 
404 	for (i = 0; i < PAGE_SIZE / bsize; i++) {
405 
406 		if ((vm_page_bits(IDX_TO_OFF(m->pindex) + i * bsize, bsize) & m->valid))
407 			continue;
408 
409 		fileaddr = vnode_pager_addr(vp,
410 			IDX_TO_OFF(m->pindex) + i * bsize, (int *)0);
411 		if (fileaddr != -1) {
412 			bp = getpbuf();
413 
414 			/* build a minimal buffer header */
415 			bp->b_flags = B_BUSY | B_READ | B_CALL;
416 			bp->b_iodone = vnode_pager_iodone;
417 			bp->b_proc = curproc;
418 			bp->b_rcred = bp->b_wcred = bp->b_proc->p_ucred;
419 			if (bp->b_rcred != NOCRED)
420 				crhold(bp->b_rcred);
421 			if (bp->b_wcred != NOCRED)
422 				crhold(bp->b_wcred);
423 			bp->b_data = (caddr_t) kva + i * bsize;
424 			bp->b_blkno = fileaddr;
425 			pbgetvp(dp, bp);
426 			bp->b_bcount = bsize;
427 			bp->b_bufsize = bsize;
428 
429 			/* do the input */
430 			VOP_STRATEGY(bp);
431 
432 			/* we definitely need to be at splbio here */
433 
434 			s = splbio();
435 			while ((bp->b_flags & B_DONE) == 0) {
436 				tsleep(bp, PVM, "vnsrd", 0);
437 			}
438 			splx(s);
439 			if ((bp->b_flags & B_ERROR) != 0)
440 				error = EIO;
441 
442 			/*
443 			 * free the buffer header back to the swap buffer pool
444 			 */
445 			relpbuf(bp);
446 			if (error)
447 				break;
448 
449 			vm_page_set_validclean(m, (i * bsize) & PAGE_MASK, bsize);
450 		} else {
451 			vm_page_set_validclean(m, (i * bsize) & PAGE_MASK, bsize);
452 			bzero((caddr_t) kva + i * bsize, bsize);
453 		}
454 	}
455 	vm_pager_unmap_page(kva);
456 	pmap_clear_modify(VM_PAGE_TO_PHYS(m));
457 	m->flags &= ~PG_ZERO;
458 	if (error) {
459 		return VM_PAGER_ERROR;
460 	}
461 	return VM_PAGER_OK;
462 
463 }
464 
465 
466 /*
467  * old style vnode pager output routine
468  */
469 static int
470 vnode_pager_input_old(object, m)
471 	vm_object_t object;
472 	vm_page_t m;
473 {
474 	struct uio auio;
475 	struct iovec aiov;
476 	int error;
477 	int size;
478 	vm_offset_t kva;
479 
480 	error = 0;
481 
482 	/*
483 	 * Return failure if beyond current EOF
484 	 */
485 	if (IDX_TO_OFF(m->pindex) >= object->un_pager.vnp.vnp_size) {
486 		return VM_PAGER_BAD;
487 	} else {
488 		size = PAGE_SIZE;
489 		if (IDX_TO_OFF(m->pindex) + size > object->un_pager.vnp.vnp_size)
490 			size = object->un_pager.vnp.vnp_size - IDX_TO_OFF(m->pindex);
491 
492 		/*
493 		 * Allocate a kernel virtual address and initialize so that
494 		 * we can use VOP_READ/WRITE routines.
495 		 */
496 		kva = vm_pager_map_page(m);
497 
498 		aiov.iov_base = (caddr_t) kva;
499 		aiov.iov_len = size;
500 		auio.uio_iov = &aiov;
501 		auio.uio_iovcnt = 1;
502 		auio.uio_offset = IDX_TO_OFF(m->pindex);
503 		auio.uio_segflg = UIO_SYSSPACE;
504 		auio.uio_rw = UIO_READ;
505 		auio.uio_resid = size;
506 		auio.uio_procp = (struct proc *) 0;
507 
508 		error = VOP_READ(object->handle, &auio, 0, curproc->p_ucred);
509 		if (!error) {
510 			register int count = size - auio.uio_resid;
511 
512 			if (count == 0)
513 				error = EINVAL;
514 			else if (count != PAGE_SIZE)
515 				bzero((caddr_t) kva + count, PAGE_SIZE - count);
516 		}
517 		vm_pager_unmap_page(kva);
518 	}
519 	pmap_clear_modify(VM_PAGE_TO_PHYS(m));
520 	m->dirty = 0;
521 	m->flags &= ~PG_ZERO;
522 	return error ? VM_PAGER_ERROR : VM_PAGER_OK;
523 }
524 
525 /*
526  * generic vnode pager input routine
527  */
528 
529 static int
530 vnode_pager_getpages(object, m, count, reqpage)
531 	vm_object_t object;
532 	vm_page_t *m;
533 	int count;
534 	int reqpage;
535 {
536 	int rtval;
537 	struct vnode *vp;
538 
539 	vp = object->handle;
540 	rtval = VOP_GETPAGES(vp, m, count*PAGE_SIZE, reqpage, 0);
541 	if (rtval == EOPNOTSUPP)
542 		return vnode_pager_leaf_getpages(object, m, count, reqpage);
543 	else
544 		return rtval;
545 }
546 
547 static int
548 vnode_pager_leaf_getpages(object, m, count, reqpage)
549 	vm_object_t object;
550 	vm_page_t *m;
551 	int count;
552 	int reqpage;
553 {
554 	vm_offset_t kva;
555 	off_t foff;
556 	int i, size, bsize, first, firstaddr;
557 	struct vnode *dp, *vp;
558 	int runpg;
559 	int runend;
560 	struct buf *bp;
561 	int s;
562 	int error = 0;
563 
564 	vp = object->handle;
565 	if (vp->v_mount == NULL)
566 		return VM_PAGER_BAD;
567 
568 	bsize = vp->v_mount->mnt_stat.f_iosize;
569 
570 	/* get the UNDERLYING device for the file with VOP_BMAP() */
571 
572 	/*
573 	 * originally, we did not check for an error return value -- assuming
574 	 * an fs always has a bmap entry point -- that assumption is wrong!!!
575 	 */
576 	foff = IDX_TO_OFF(m[reqpage]->pindex);
577 
578 	/*
579 	 * if we can't bmap, use old VOP code
580 	 */
581 	if (VOP_BMAP(vp, 0, &dp, 0, NULL, NULL)) {
582 		for (i = 0; i < count; i++) {
583 			if (i != reqpage) {
584 				vnode_pager_freepage(m[i]);
585 			}
586 		}
587 		cnt.v_vnodein++;
588 		cnt.v_vnodepgsin++;
589 		return vnode_pager_input_old(object, m[reqpage]);
590 
591 		/*
592 		 * if the blocksize is smaller than a page size, then use
593 		 * special small filesystem code.  NFS sometimes has a small
594 		 * blocksize, but it can handle large reads itself.
595 		 */
596 	} else if ((PAGE_SIZE / bsize) > 1 &&
597 	    (vp->v_mount->mnt_stat.f_type != MOUNT_NFS)) {
598 
599 		for (i = 0; i < count; i++) {
600 			if (i != reqpage) {
601 				vnode_pager_freepage(m[i]);
602 			}
603 		}
604 		cnt.v_vnodein++;
605 		cnt.v_vnodepgsin++;
606 		return vnode_pager_input_smlfs(object, m[reqpage]);
607 	}
608 	/*
609 	 * if ANY DEV_BSIZE blocks are valid on a large filesystem block
610 	 * then, the entire page is valid --
611 	 * XXX no it isn't
612 	 */
613 
614 	if (m[reqpage]->valid != VM_PAGE_BITS_ALL)
615 	    m[reqpage]->valid = 0;
616 
617 	if (m[reqpage]->valid) {
618 		m[reqpage]->valid = VM_PAGE_BITS_ALL;
619 		for (i = 0; i < count; i++) {
620 			if (i != reqpage)
621 				vnode_pager_freepage(m[i]);
622 		}
623 		return VM_PAGER_OK;
624 	}
625 
626 	/*
627 	 * here on direct device I/O
628 	 */
629 
630 	firstaddr = -1;
631 	/*
632 	 * calculate the run that includes the required page
633 	 */
634 	for(first = 0, i = 0; i < count; i = runend) {
635 		firstaddr = vnode_pager_addr(vp,
636 			IDX_TO_OFF(m[i]->pindex), &runpg);
637 		if (firstaddr == -1) {
638 			if (i == reqpage && foff < object->un_pager.vnp.vnp_size) {
639 				panic("vnode_pager_getpages: unexpected missing page: firstaddr: %d, foff: %ld, vnp_size: %d",
640 			   	 firstaddr, foff, object->un_pager.vnp.vnp_size);
641 			}
642 			vnode_pager_freepage(m[i]);
643 			runend = i + 1;
644 			first = runend;
645 			continue;
646 		}
647 		runend = i + runpg;
648 		if (runend <= reqpage) {
649 			int j;
650 			for (j = i; j < runend; j++) {
651 				vnode_pager_freepage(m[j]);
652 			}
653 		} else {
654 			if (runpg < (count - first)) {
655 				for (i = first + runpg; i < count; i++)
656 					vnode_pager_freepage(m[i]);
657 				count = first + runpg;
658 			}
659 			break;
660 		}
661 		first = runend;
662 	}
663 
664 	/*
665 	 * the first and last page have been calculated now, move input pages
666 	 * to be zero based...
667 	 */
668 	if (first != 0) {
669 		for (i = first; i < count; i++) {
670 			m[i - first] = m[i];
671 		}
672 		count -= first;
673 		reqpage -= first;
674 	}
675 
676 	/*
677 	 * calculate the file virtual address for the transfer
678 	 */
679 	foff = IDX_TO_OFF(m[0]->pindex);
680 
681 	/*
682 	 * calculate the size of the transfer
683 	 */
684 	size = count * PAGE_SIZE;
685 	if ((foff + size) > object->un_pager.vnp.vnp_size)
686 		size = object->un_pager.vnp.vnp_size - foff;
687 
688 	/*
689 	 * round up physical size for real devices
690 	 */
691 	if (dp->v_type == VBLK || dp->v_type == VCHR)
692 		size = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
693 
694 	bp = getpbuf();
695 	kva = (vm_offset_t) bp->b_data;
696 
697 	/*
698 	 * and map the pages to be read into the kva
699 	 */
700 	pmap_qenter(kva, m, count);
701 
702 	/* build a minimal buffer header */
703 	bp->b_flags = B_BUSY | B_READ | B_CALL;
704 	bp->b_iodone = vnode_pager_iodone;
705 	/* B_PHYS is not set, but it is nice to fill this in */
706 	bp->b_proc = curproc;
707 	bp->b_rcred = bp->b_wcred = bp->b_proc->p_ucred;
708 	if (bp->b_rcred != NOCRED)
709 		crhold(bp->b_rcred);
710 	if (bp->b_wcred != NOCRED)
711 		crhold(bp->b_wcred);
712 	bp->b_blkno = firstaddr;
713 	pbgetvp(dp, bp);
714 	bp->b_bcount = size;
715 	bp->b_bufsize = size;
716 
717 	cnt.v_vnodein++;
718 	cnt.v_vnodepgsin += count;
719 
720 	/* do the input */
721 	VOP_STRATEGY(bp);
722 
723 	s = splbio();
724 	/* we definitely need to be at splbio here */
725 
726 	while ((bp->b_flags & B_DONE) == 0) {
727 		tsleep(bp, PVM, "vnread", 0);
728 	}
729 	splx(s);
730 	if ((bp->b_flags & B_ERROR) != 0)
731 		error = EIO;
732 
733 	if (!error) {
734 		if (size != count * PAGE_SIZE)
735 			bzero((caddr_t) kva + size, PAGE_SIZE * count - size);
736 	}
737 	pmap_qremove(kva, count);
738 
739 	/*
740 	 * free the buffer header back to the swap buffer pool
741 	 */
742 	relpbuf(bp);
743 
744 	for (i = 0; i < count; i++) {
745 		pmap_clear_modify(VM_PAGE_TO_PHYS(m[i]));
746 		m[i]->dirty = 0;
747 		m[i]->valid = VM_PAGE_BITS_ALL;
748 		m[i]->flags &= ~PG_ZERO;
749 		if (i != reqpage) {
750 
751 			/*
752 			 * whether or not to leave the page activated is up in
753 			 * the air, but we should put the page on a page queue
754 			 * somewhere. (it already is in the object). Result:
755 			 * It appears that emperical results show that
756 			 * deactivating pages is best.
757 			 */
758 
759 			/*
760 			 * just in case someone was asking for this page we
761 			 * now tell them that it is ok to use
762 			 */
763 			if (!error) {
764 				vm_page_deactivate(m[i]);
765 				PAGE_WAKEUP(m[i]);
766 			} else {
767 				vnode_pager_freepage(m[i]);
768 			}
769 		}
770 	}
771 	if (error) {
772 		printf("vnode_pager_getpages: I/O read error\n");
773 	}
774 	return (error ? VM_PAGER_ERROR : VM_PAGER_OK);
775 }
776 
777 static int
778 vnode_pager_putpages(object, m, count, sync, rtvals)
779 	vm_object_t object;
780 	vm_page_t *m;
781 	int count;
782 	boolean_t sync;
783 	int *rtvals;
784 {
785 	int rtval;
786 	struct vnode *vp;
787 
788 	vp = object->handle;
789 	rtval = VOP_PUTPAGES(vp, m, count*PAGE_SIZE, sync, rtvals, 0);
790 	if (rtval == EOPNOTSUPP)
791 		return vnode_pager_leaf_putpages(object, m, count, sync, rtvals);
792 	else
793 		return rtval;
794 }
795 
796 /*
797  * generic vnode pager output routine
798  */
799 static int
800 vnode_pager_leaf_putpages(object, m, count, sync, rtvals)
801 	vm_object_t object;
802 	vm_page_t *m;
803 	int count;
804 	boolean_t sync;
805 	int *rtvals;
806 {
807 	int i;
808 
809 	struct vnode *vp;
810 	int maxsize, ncount;
811 	vm_ooffset_t poffset;
812 	struct uio auio;
813 	struct iovec aiov;
814 	int error;
815 
816 	vp = object->handle;;
817 	for (i = 0; i < count; i++)
818 		rtvals[i] = VM_PAGER_AGAIN;
819 
820 	if ((int) m[0]->pindex < 0) {
821 		printf("vnode_pager_putpages: attempt to write meta-data!!! -- 0x%x(%x)\n", m[0]->pindex, m[0]->dirty);
822 		rtvals[0] = VM_PAGER_BAD;
823 		return VM_PAGER_BAD;
824 	}
825 
826 	maxsize = count * PAGE_SIZE;
827 	ncount = count;
828 
829 	poffset = IDX_TO_OFF(m[0]->pindex);
830 	if (maxsize + poffset > object->un_pager.vnp.vnp_size) {
831 		if (object->un_pager.vnp.vnp_size > poffset)
832 			maxsize = object->un_pager.vnp.vnp_size - poffset;
833 		else
834 			maxsize = 0;
835 		ncount = btoc(maxsize);
836 		if (ncount < count) {
837 			for (i = ncount; i < count; i++) {
838 				rtvals[i] = VM_PAGER_BAD;
839 			}
840 #ifdef BOGUS
841 			if (ncount == 0) {
842 				printf("vnode_pager_putpages: write past end of file: %d, %lu\n",
843 					poffset,
844 					(unsigned long) object->un_pager.vnp.vnp_size);
845 				return rtvals[0];
846 			}
847 #endif
848 		}
849 	}
850 
851 	for (i = 0; i < count; i++) {
852 		m[i]->busy++;
853 		m[i]->flags &= ~PG_BUSY;
854 	}
855 
856 	aiov.iov_base = (caddr_t) 0;
857 	aiov.iov_len = maxsize;
858 	auio.uio_iov = &aiov;
859 	auio.uio_iovcnt = 1;
860 	auio.uio_offset = poffset;
861 	auio.uio_segflg = UIO_NOCOPY;
862 	auio.uio_rw = UIO_WRITE;
863 	auio.uio_resid = maxsize;
864 	auio.uio_procp = (struct proc *) 0;
865 	error = VOP_WRITE(vp, &auio, IO_VMIO|(sync?IO_SYNC:0), curproc->p_ucred);
866 	cnt.v_vnodeout++;
867 	cnt.v_vnodepgsout += ncount;
868 
869 	if (error) {
870 		printf("vnode_pager_putpages: I/O error %d\n", error);
871 	}
872 	if (auio.uio_resid) {
873 		printf("vnode_pager_putpages: residual I/O %d at %ld\n",
874 			auio.uio_resid, m[0]->pindex);
875 	}
876 	for (i = 0; i < count; i++) {
877 		m[i]->busy--;
878 		if (i < ncount) {
879 			rtvals[i] = VM_PAGER_OK;
880 		}
881 		if ((m[i]->busy == 0) && (m[i]->flags & PG_WANTED))
882 			wakeup(m[i]);
883 	}
884 	return rtvals[0];
885 }
886 
887 struct vnode *
888 vnode_pager_lock(object)
889 	vm_object_t object;
890 {
891 	struct proc *p = curproc;	/* XXX */
892 
893 	for (; object != NULL; object = object->backing_object) {
894 		if (object->type != OBJT_VNODE)
895 			continue;
896 		if (object->flags & OBJ_DEAD)
897 			return NULL;
898 
899 		while (vget(object->handle,
900 			LK_NOPAUSE | LK_SHARED | LK_RETRY | LK_CANRECURSE, p)) {
901 			printf("vnode_pager_lock: retrying\n");
902 		}
903 		return object->handle;
904 	}
905 	return NULL;
906 }
907