xref: /freebsd/sys/vm/vnode_pager.c (revision 2da199da53835ee2d9228a60717fd2d0fccf9e50)
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 1.102 1999/01/21 08:29:12 dillon 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 void 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 int vnode_pbuf_freecnt = -1;	/* start out unlimited */
92 
93 
94 /*
95  * Allocate (or lookup) pager for a vnode.
96  * Handle is a vnode pointer.
97  */
98 vm_object_t
99 vnode_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
100 		  vm_ooffset_t offset)
101 {
102 	vm_object_t object;
103 	struct vnode *vp;
104 
105 	/*
106 	 * Pageout to vnode, no can do yet.
107 	 */
108 	if (handle == NULL)
109 		return (NULL);
110 
111 	/*
112 	 * XXX hack - This initialization should be put somewhere else.
113 	 */
114 	if (vnode_pbuf_freecnt < 0) {
115 	    vnode_pbuf_freecnt = nswbuf / 2 + 1;
116 	}
117 
118 	vp = (struct vnode *) handle;
119 
120 	/*
121 	 * Prevent race condition when allocating the object. This
122 	 * can happen with NFS vnodes since the nfsnode isn't locked.
123 	 */
124 	while (vp->v_flag & VOLOCK) {
125 		vp->v_flag |= VOWANT;
126 		tsleep(vp, PVM, "vnpobj", 0);
127 	}
128 	vp->v_flag |= VOLOCK;
129 
130 	/*
131 	 * If the object is being terminated, wait for it to
132 	 * go away.
133 	 */
134 	while (((object = vp->v_object) != NULL) &&
135 		(object->flags & OBJ_DEAD)) {
136 		tsleep(object, PVM, "vadead", 0);
137 	}
138 
139 	if (vp->v_usecount == 0)
140 		panic("vnode_pager_alloc: no vnode reference");
141 
142 	if (object == NULL) {
143 		/*
144 		 * And an object of the appropriate size
145 		 */
146 		object = vm_object_allocate(OBJT_VNODE, OFF_TO_IDX(round_page(size)));
147 		object->flags = 0;
148 
149 		object->un_pager.vnp.vnp_size = size;
150 
151 		object->handle = handle;
152 		vp->v_object = object;
153 		vp->v_usecount++;
154 	} else {
155 		object->ref_count++;
156 		vp->v_usecount++;
157 	}
158 
159 	vp->v_flag &= ~VOLOCK;
160 	if (vp->v_flag & VOWANT) {
161 		vp->v_flag &= ~VOWANT;
162 		wakeup(vp);
163 	}
164 	return (object);
165 }
166 
167 static void
168 vnode_pager_dealloc(object)
169 	vm_object_t object;
170 {
171 	register struct vnode *vp = object->handle;
172 
173 	if (vp == NULL)
174 		panic("vnode_pager_dealloc: pager already dealloced");
175 
176 	vm_object_pip_wait(object, "vnpdea");
177 
178 	object->handle = NULL;
179 	object->type = OBJT_DEAD;
180 	vp->v_object = NULL;
181 	vp->v_flag &= ~(VTEXT | VOBJBUF);
182 }
183 
184 static boolean_t
185 vnode_pager_haspage(object, pindex, before, after)
186 	vm_object_t object;
187 	vm_pindex_t pindex;
188 	int *before;
189 	int *after;
190 {
191 	struct vnode *vp = object->handle;
192 	daddr_t bn;
193 	int err;
194 	daddr_t reqblock;
195 	int poff;
196 	int bsize;
197 	int pagesperblock, blocksperpage;
198 
199 	if ((vp == NULL) || (vp->v_flag & VDOOMED))
200 		return FALSE;
201 
202 	/*
203 	 * If filesystem no longer mounted or offset beyond end of file we do
204 	 * not have the page.
205 	 */
206 	if ((vp->v_mount == NULL) ||
207 		(IDX_TO_OFF(pindex) >= object->un_pager.vnp.vnp_size))
208 		return FALSE;
209 
210 	bsize = vp->v_mount->mnt_stat.f_iosize;
211 	pagesperblock = bsize / PAGE_SIZE;
212 	blocksperpage = 0;
213 	if (pagesperblock > 0) {
214 		reqblock = pindex / pagesperblock;
215 	} else {
216 		blocksperpage = (PAGE_SIZE / bsize);
217 		reqblock = pindex * blocksperpage;
218 	}
219 	err = VOP_BMAP(vp, reqblock, (struct vnode **) 0, &bn,
220 		after, before);
221 	if (err)
222 		return TRUE;
223 	if ( bn == -1)
224 		return FALSE;
225 	if (pagesperblock > 0) {
226 		poff = pindex - (reqblock * pagesperblock);
227 		if (before) {
228 			*before *= pagesperblock;
229 			*before += poff;
230 		}
231 		if (after) {
232 			int numafter;
233 			*after *= pagesperblock;
234 			numafter = pagesperblock - (poff + 1);
235 			if (IDX_TO_OFF(pindex + numafter) > object->un_pager.vnp.vnp_size) {
236 				numafter = OFF_TO_IDX((object->un_pager.vnp.vnp_size - IDX_TO_OFF(pindex)));
237 			}
238 			*after += numafter;
239 		}
240 	} else {
241 		if (before) {
242 			*before /= blocksperpage;
243 		}
244 
245 		if (after) {
246 			*after /= blocksperpage;
247 		}
248 	}
249 	return TRUE;
250 }
251 
252 /*
253  * Lets the VM system know about a change in size for a file.
254  * We adjust our own internal size and flush any cached pages in
255  * the associated object that are affected by the size change.
256  *
257  * Note: this routine may be invoked as a result of a pager put
258  * operation (possibly at object termination time), so we must be careful.
259  */
260 void
261 vnode_pager_setsize(vp, nsize)
262 	struct vnode *vp;
263 	vm_ooffset_t nsize;
264 {
265 	vm_pindex_t nobjsize;
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 	nobjsize = OFF_TO_IDX(nsize + PAGE_MASK);
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_freeze_copyopts(object, OFF_TO_IDX(nsize), object->size);
284 		if (nobjsize < object->size) {
285 			vm_object_page_remove(object, nobjsize, object->size,
286 				FALSE);
287 		}
288 		/*
289 		 * this gets rid of garbage at the end of a page that is now
290 		 * only partially backed by the vnode...
291 		 */
292 		if (nsize & PAGE_MASK) {
293 			vm_offset_t kva;
294 			vm_page_t m;
295 
296 			m = vm_page_lookup(object, OFF_TO_IDX(nsize));
297 			if (m) {
298 				kva = vm_pager_map_page(m);
299 				bzero((caddr_t) kva + (nsize & PAGE_MASK),
300 				    (int) (round_page(nsize) - nsize));
301 				vm_pager_unmap_page(kva);
302 			}
303 		}
304 	}
305 	object->un_pager.vnp.vnp_size = nsize;
306 	object->size = nobjsize;
307 }
308 
309 void
310 vnode_pager_freepage(m)
311 	vm_page_t m;
312 {
313 	vm_page_free(m);
314 }
315 
316 /*
317  * calculate the linear (byte) disk address of specified virtual
318  * file address
319  */
320 static vm_offset_t
321 vnode_pager_addr(vp, address, run)
322 	struct vnode *vp;
323 	vm_ooffset_t address;
324 	int *run;
325 {
326 	int rtaddress;
327 	int bsize;
328 	daddr_t block;
329 	struct vnode *rtvp;
330 	int err;
331 	daddr_t vblock;
332 	int voffset;
333 
334 	if ((int) address < 0)
335 		return -1;
336 
337 	if (vp->v_mount == NULL)
338 		return -1;
339 
340 	bsize = vp->v_mount->mnt_stat.f_iosize;
341 	vblock = address / bsize;
342 	voffset = address % bsize;
343 
344 	err = VOP_BMAP(vp, vblock, &rtvp, &block, run, NULL);
345 
346 	if (err || (block == -1))
347 		rtaddress = -1;
348 	else {
349 		rtaddress = block + voffset / DEV_BSIZE;
350 		if( run) {
351 			*run += 1;
352 			*run *= bsize/PAGE_SIZE;
353 			*run -= voffset/PAGE_SIZE;
354 		}
355 	}
356 
357 	return rtaddress;
358 }
359 
360 /*
361  * interrupt routine for I/O completion
362  */
363 static void
364 vnode_pager_iodone(bp)
365 	struct buf *bp;
366 {
367 	bp->b_flags |= B_DONE;
368 	wakeup(bp);
369 }
370 
371 /*
372  * small block file system vnode pager input
373  */
374 static int
375 vnode_pager_input_smlfs(object, m)
376 	vm_object_t object;
377 	vm_page_t m;
378 {
379 	int i;
380 	int s;
381 	struct vnode *dp, *vp;
382 	struct buf *bp;
383 	vm_offset_t kva;
384 	int fileaddr;
385 	vm_offset_t bsize;
386 	int error = 0;
387 
388 	vp = object->handle;
389 	if (vp->v_mount == NULL)
390 		return VM_PAGER_BAD;
391 
392 	bsize = vp->v_mount->mnt_stat.f_iosize;
393 
394 
395 	VOP_BMAP(vp, 0, &dp, 0, NULL, NULL);
396 
397 	kva = vm_pager_map_page(m);
398 
399 	for (i = 0; i < PAGE_SIZE / bsize; i++) {
400 
401 		if ((vm_page_bits(IDX_TO_OFF(m->pindex) + i * bsize, bsize) & m->valid))
402 			continue;
403 
404 		fileaddr = vnode_pager_addr(vp,
405 			IDX_TO_OFF(m->pindex) + i * bsize, (int *)0);
406 		if (fileaddr != -1) {
407 			bp = getpbuf(&vnode_pbuf_freecnt);
408 
409 			/* build a minimal buffer header */
410 			bp->b_flags = B_BUSY | B_READ | B_CALL;
411 			bp->b_iodone = vnode_pager_iodone;
412 			bp->b_proc = curproc;
413 			bp->b_rcred = bp->b_wcred = bp->b_proc->p_ucred;
414 			if (bp->b_rcred != NOCRED)
415 				crhold(bp->b_rcred);
416 			if (bp->b_wcred != NOCRED)
417 				crhold(bp->b_wcred);
418 			bp->b_data = (caddr_t) kva + i * bsize;
419 			bp->b_blkno = fileaddr;
420 			pbgetvp(dp, bp);
421 			bp->b_bcount = bsize;
422 			bp->b_bufsize = bsize;
423 
424 			/* do the input */
425 			VOP_STRATEGY(bp->b_vp, bp);
426 
427 			/* we definitely need to be at splvm here */
428 
429 			s = splvm();
430 			while ((bp->b_flags & B_DONE) == 0) {
431 				tsleep(bp, PVM, "vnsrd", 0);
432 			}
433 			splx(s);
434 			if ((bp->b_flags & B_ERROR) != 0)
435 				error = EIO;
436 
437 			/*
438 			 * free the buffer header back to the swap buffer pool
439 			 */
440 			relpbuf(bp, &vnode_pbuf_freecnt);
441 			if (error)
442 				break;
443 
444 			vm_page_set_validclean(m, (i * bsize) & PAGE_MASK, bsize);
445 		} else {
446 			vm_page_set_validclean(m, (i * bsize) & PAGE_MASK, bsize);
447 			bzero((caddr_t) kva + i * bsize, bsize);
448 		}
449 	}
450 	vm_pager_unmap_page(kva);
451 	pmap_clear_modify(VM_PAGE_TO_PHYS(m));
452 	vm_page_flag_clear(m, PG_ZERO);
453 	if (error) {
454 		return VM_PAGER_ERROR;
455 	}
456 	return VM_PAGER_OK;
457 
458 }
459 
460 
461 /*
462  * old style vnode pager output routine
463  */
464 static int
465 vnode_pager_input_old(object, m)
466 	vm_object_t object;
467 	vm_page_t m;
468 {
469 	struct uio auio;
470 	struct iovec aiov;
471 	int error;
472 	int size;
473 	vm_offset_t kva;
474 
475 	error = 0;
476 
477 	/*
478 	 * Return failure if beyond current EOF
479 	 */
480 	if (IDX_TO_OFF(m->pindex) >= object->un_pager.vnp.vnp_size) {
481 		return VM_PAGER_BAD;
482 	} else {
483 		size = PAGE_SIZE;
484 		if (IDX_TO_OFF(m->pindex) + size > object->un_pager.vnp.vnp_size)
485 			size = object->un_pager.vnp.vnp_size - IDX_TO_OFF(m->pindex);
486 
487 		/*
488 		 * Allocate a kernel virtual address and initialize so that
489 		 * we can use VOP_READ/WRITE routines.
490 		 */
491 		kva = vm_pager_map_page(m);
492 
493 		aiov.iov_base = (caddr_t) kva;
494 		aiov.iov_len = size;
495 		auio.uio_iov = &aiov;
496 		auio.uio_iovcnt = 1;
497 		auio.uio_offset = IDX_TO_OFF(m->pindex);
498 		auio.uio_segflg = UIO_SYSSPACE;
499 		auio.uio_rw = UIO_READ;
500 		auio.uio_resid = size;
501 		auio.uio_procp = curproc;
502 
503 		error = VOP_READ(object->handle, &auio, 0, curproc->p_ucred);
504 		if (!error) {
505 			register int count = size - auio.uio_resid;
506 
507 			if (count == 0)
508 				error = EINVAL;
509 			else if (count != PAGE_SIZE)
510 				bzero((caddr_t) kva + count, PAGE_SIZE - count);
511 		}
512 		vm_pager_unmap_page(kva);
513 	}
514 	pmap_clear_modify(VM_PAGE_TO_PHYS(m));
515 	m->dirty = 0;
516 	vm_page_flag_clear(m, PG_ZERO);
517 	if (!error)
518 		m->valid = VM_PAGE_BITS_ALL;
519 	return error ? VM_PAGER_ERROR : VM_PAGER_OK;
520 }
521 
522 /*
523  * generic vnode pager input routine
524  */
525 
526 /*
527  * EOPNOTSUPP is no longer legal.  For local media VFS's that do not
528  * implement their own VOP_GETPAGES, their VOP_GETPAGES should call to
529  * vnode_pager_generic_getpages() to implement the previous behaviour.
530  *
531  * All other FS's should use the bypass to get to the local media
532  * backing vp's VOP_GETPAGES.
533  */
534 static int
535 vnode_pager_getpages(object, m, count, reqpage)
536 	vm_object_t object;
537 	vm_page_t *m;
538 	int count;
539 	int reqpage;
540 {
541 	int rtval;
542 	struct vnode *vp;
543 	int bytes = count * PAGE_SIZE;
544 
545 	vp = object->handle;
546 	/*
547 	 * XXX temporary diagnostic message to help track stale FS code,
548 	 * Returning EOPNOTSUPP from here may make things unhappy.
549 	 */
550 	rtval = VOP_GETPAGES(vp, m, bytes, reqpage, 0);
551 	if (rtval == EOPNOTSUPP) {
552 	    printf("vnode_pager: *** WARNING *** stale FS getpages\n");
553 	    rtval = vnode_pager_generic_getpages( vp, m, bytes, reqpage);
554 	}
555 	return rtval;
556 }
557 
558 
559 /*
560  * This is now called from local media FS's to operate against their
561  * own vnodes if they fail to implement VOP_GETPAGES.
562  */
563 int
564 vnode_pager_generic_getpages(vp, m, bytecount, reqpage)
565 	struct vnode *vp;
566 	vm_page_t *m;
567 	int bytecount;
568 	int reqpage;
569 {
570 	vm_object_t object;
571 	vm_offset_t kva;
572 	off_t foff, tfoff, nextoff;
573 	int i, size, bsize, first, firstaddr;
574 	struct vnode *dp;
575 	int runpg;
576 	int runend;
577 	struct buf *bp;
578 	int s;
579 	int count;
580 	int error = 0;
581 
582 	object = vp->v_object;
583 	count = bytecount / PAGE_SIZE;
584 
585 	if (vp->v_mount == NULL)
586 		return VM_PAGER_BAD;
587 
588 	bsize = vp->v_mount->mnt_stat.f_iosize;
589 
590 	/* get the UNDERLYING device for the file with VOP_BMAP() */
591 
592 	/*
593 	 * originally, we did not check for an error return value -- assuming
594 	 * an fs always has a bmap entry point -- that assumption is wrong!!!
595 	 */
596 	foff = IDX_TO_OFF(m[reqpage]->pindex);
597 
598 	/*
599 	 * if we can't bmap, use old VOP code
600 	 */
601 	if (VOP_BMAP(vp, 0, &dp, 0, NULL, NULL)) {
602 		for (i = 0; i < count; i++) {
603 			if (i != reqpage) {
604 				vnode_pager_freepage(m[i]);
605 			}
606 		}
607 		cnt.v_vnodein++;
608 		cnt.v_vnodepgsin++;
609 		return vnode_pager_input_old(object, m[reqpage]);
610 
611 		/*
612 		 * if the blocksize is smaller than a page size, then use
613 		 * special small filesystem code.  NFS sometimes has a small
614 		 * blocksize, but it can handle large reads itself.
615 		 */
616 	} else if ((PAGE_SIZE / bsize) > 1 &&
617 	    (vp->v_mount->mnt_stat.f_type != nfs_mount_type)) {
618 		for (i = 0; i < count; i++) {
619 			if (i != reqpage) {
620 				vnode_pager_freepage(m[i]);
621 			}
622 		}
623 		cnt.v_vnodein++;
624 		cnt.v_vnodepgsin++;
625 		return vnode_pager_input_smlfs(object, m[reqpage]);
626 	}
627 	/*
628 	 * if ANY DEV_BSIZE blocks are valid on a large filesystem block
629 	 * then, the entire page is valid --
630 	 * XXX no it isn't
631 	 */
632 
633 	if (m[reqpage]->valid != VM_PAGE_BITS_ALL)
634 	    m[reqpage]->valid = 0;
635 
636 	if (m[reqpage]->valid) {
637 		m[reqpage]->valid = VM_PAGE_BITS_ALL;
638 		for (i = 0; i < count; i++) {
639 			if (i != reqpage)
640 				vnode_pager_freepage(m[i]);
641 		}
642 		return VM_PAGER_OK;
643 	}
644 
645 	/*
646 	 * here on direct device I/O
647 	 */
648 
649 	firstaddr = -1;
650 	/*
651 	 * calculate the run that includes the required page
652 	 */
653 	for(first = 0, i = 0; i < count; i = runend) {
654 		firstaddr = vnode_pager_addr(vp,
655 			IDX_TO_OFF(m[i]->pindex), &runpg);
656 		if (firstaddr == -1) {
657 			if (i == reqpage && foff < object->un_pager.vnp.vnp_size) {
658 				/* XXX no %qd in kernel. */
659 				panic("vnode_pager_getpages: unexpected missing page: firstaddr: %d, foff: 0x%lx%08lx, vnp_size: 0x%lx%08lx",
660 			   	 firstaddr, (u_long)(foff >> 32),
661 			   	 (u_long)(u_int32_t)foff,
662 				 (u_long)(u_int32_t)
663 				 (object->un_pager.vnp.vnp_size >> 32),
664 				 (u_long)(u_int32_t)
665 				 object->un_pager.vnp.vnp_size);
666 			}
667 			vnode_pager_freepage(m[i]);
668 			runend = i + 1;
669 			first = runend;
670 			continue;
671 		}
672 		runend = i + runpg;
673 		if (runend <= reqpage) {
674 			int j;
675 			for (j = i; j < runend; j++) {
676 				vnode_pager_freepage(m[j]);
677 			}
678 		} else {
679 			if (runpg < (count - first)) {
680 				for (i = first + runpg; i < count; i++)
681 					vnode_pager_freepage(m[i]);
682 				count = first + runpg;
683 			}
684 			break;
685 		}
686 		first = runend;
687 	}
688 
689 	/*
690 	 * the first and last page have been calculated now, move input pages
691 	 * to be zero based...
692 	 */
693 	if (first != 0) {
694 		for (i = first; i < count; i++) {
695 			m[i - first] = m[i];
696 		}
697 		count -= first;
698 		reqpage -= first;
699 	}
700 
701 	/*
702 	 * calculate the file virtual address for the transfer
703 	 */
704 	foff = IDX_TO_OFF(m[0]->pindex);
705 
706 	/*
707 	 * calculate the size of the transfer
708 	 */
709 	size = count * PAGE_SIZE;
710 	if ((foff + size) > object->un_pager.vnp.vnp_size)
711 		size = object->un_pager.vnp.vnp_size - foff;
712 
713 	/*
714 	 * round up physical size for real devices
715 	 */
716 	if (dp->v_type == VBLK || dp->v_type == VCHR)
717 		size = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
718 
719 	bp = getpbuf(&vnode_pbuf_freecnt);
720 	kva = (vm_offset_t) bp->b_data;
721 
722 	/*
723 	 * and map the pages to be read into the kva
724 	 */
725 	pmap_qenter(kva, m, count);
726 
727 	/* build a minimal buffer header */
728 	bp->b_flags = B_BUSY | B_READ | B_CALL;
729 	bp->b_iodone = vnode_pager_iodone;
730 	/* B_PHYS is not set, but it is nice to fill this in */
731 	bp->b_proc = curproc;
732 	bp->b_rcred = bp->b_wcred = bp->b_proc->p_ucred;
733 	if (bp->b_rcred != NOCRED)
734 		crhold(bp->b_rcred);
735 	if (bp->b_wcred != NOCRED)
736 		crhold(bp->b_wcred);
737 	bp->b_blkno = firstaddr;
738 	pbgetvp(dp, bp);
739 	bp->b_bcount = size;
740 	bp->b_bufsize = size;
741 
742 	cnt.v_vnodein++;
743 	cnt.v_vnodepgsin += count;
744 
745 	/* do the input */
746 	VOP_STRATEGY(bp->b_vp, bp);
747 
748 	s = splvm();
749 	/* we definitely need to be at splvm here */
750 
751 	while ((bp->b_flags & B_DONE) == 0) {
752 		tsleep(bp, PVM, "vnread", 0);
753 	}
754 	splx(s);
755 	if ((bp->b_flags & B_ERROR) != 0)
756 		error = EIO;
757 
758 	if (!error) {
759 		if (size != count * PAGE_SIZE)
760 			bzero((caddr_t) kva + size, PAGE_SIZE * count - size);
761 	}
762 	pmap_qremove(kva, count);
763 
764 	/*
765 	 * free the buffer header back to the swap buffer pool
766 	 */
767 	relpbuf(bp, &vnode_pbuf_freecnt);
768 
769 	for (i = 0, tfoff = foff; i < count; i++, tfoff = nextoff) {
770 		vm_page_t mt;
771 
772 		nextoff = tfoff + PAGE_SIZE;
773 		mt = m[i];
774 
775 		if (nextoff <= size) {
776 			mt->valid = VM_PAGE_BITS_ALL;
777 			mt->dirty = 0;
778 			pmap_clear_modify(VM_PAGE_TO_PHYS(mt));
779 		} else {
780 			int nvalid = ((size + DEV_BSIZE - 1) - tfoff) & ~(DEV_BSIZE - 1);
781 			vm_page_set_validclean(mt, 0, nvalid);
782 		}
783 
784 		vm_page_flag_clear(mt, PG_ZERO);
785 		if (i != reqpage) {
786 
787 			/*
788 			 * whether or not to leave the page activated is up in
789 			 * the air, but we should put the page on a page queue
790 			 * somewhere. (it already is in the object). Result:
791 			 * It appears that emperical results show that
792 			 * deactivating pages is best.
793 			 */
794 
795 			/*
796 			 * just in case someone was asking for this page we
797 			 * now tell them that it is ok to use
798 			 */
799 			if (!error) {
800 				if (mt->flags & PG_WANTED)
801 					vm_page_activate(mt);
802 				else
803 					vm_page_deactivate(mt);
804 				vm_page_wakeup(mt);
805 			} else {
806 				vnode_pager_freepage(mt);
807 			}
808 		}
809 	}
810 	if (error) {
811 		printf("vnode_pager_getpages: I/O read error\n");
812 	}
813 	return (error ? VM_PAGER_ERROR : VM_PAGER_OK);
814 }
815 
816 /*
817  * EOPNOTSUPP is no longer legal.  For local media VFS's that do not
818  * implement their own VOP_PUTPAGES, their VOP_PUTPAGES should call to
819  * vnode_pager_generic_putpages() to implement the previous behaviour.
820  *
821  * All other FS's should use the bypass to get to the local media
822  * backing vp's VOP_PUTPAGES.
823  */
824 static void
825 vnode_pager_putpages(object, m, count, sync, rtvals)
826 	vm_object_t object;
827 	vm_page_t *m;
828 	int count;
829 	boolean_t sync;
830 	int *rtvals;
831 {
832 	int rtval;
833 	struct vnode *vp;
834 	int bytes = count * PAGE_SIZE;
835 
836 	vp = object->handle;
837 	rtval = VOP_PUTPAGES(vp, m, bytes, sync, rtvals, 0);
838 	if (rtval == EOPNOTSUPP) {
839 	    printf("vnode_pager: *** WARNING *** stale FS putpages\n");
840 	    rtval = vnode_pager_generic_putpages( vp, m, bytes, sync, rtvals);
841 	}
842 }
843 
844 
845 /*
846  * This is now called from local media FS's to operate against their
847  * own vnodes if they fail to implement VOP_GETPAGES.
848  */
849 int
850 vnode_pager_generic_putpages(vp, m, bytecount, flags, rtvals)
851 	struct vnode *vp;
852 	vm_page_t *m;
853 	int bytecount;
854 	int flags;
855 	int *rtvals;
856 {
857 	int i;
858 	vm_object_t object;
859 	int count;
860 
861 	int maxsize, ncount;
862 	vm_ooffset_t poffset;
863 	struct uio auio;
864 	struct iovec aiov;
865 	int error;
866 	int ioflags;
867 
868 	object = vp->v_object;
869 	count = bytecount / PAGE_SIZE;
870 
871 	for (i = 0; i < count; i++)
872 		rtvals[i] = VM_PAGER_AGAIN;
873 
874 	if ((int) m[0]->pindex < 0) {
875 		printf("vnode_pager_putpages: attempt to write meta-data!!! -- 0x%x(%x)\n",
876 			m[0]->pindex, m[0]->dirty);
877 		rtvals[0] = VM_PAGER_BAD;
878 		return VM_PAGER_BAD;
879 	}
880 
881 	maxsize = count * PAGE_SIZE;
882 	ncount = count;
883 
884 	poffset = IDX_TO_OFF(m[0]->pindex);
885 	if (maxsize + poffset > object->un_pager.vnp.vnp_size) {
886 		if (object->un_pager.vnp.vnp_size > poffset)
887 			maxsize = object->un_pager.vnp.vnp_size - poffset;
888 		else
889 			maxsize = 0;
890 		ncount = btoc(maxsize);
891 		if (ncount < count) {
892 			for (i = ncount; i < count; i++) {
893 				rtvals[i] = VM_PAGER_BAD;
894 			}
895 		}
896 	}
897 
898 	ioflags = IO_VMIO;
899 	ioflags |= (flags & (VM_PAGER_PUT_SYNC | VM_PAGER_PUT_INVAL)) ? IO_SYNC: 0;
900 	ioflags |= (flags & VM_PAGER_PUT_INVAL) ? IO_INVAL: 0;
901 
902 	aiov.iov_base = (caddr_t) 0;
903 	aiov.iov_len = maxsize;
904 	auio.uio_iov = &aiov;
905 	auio.uio_iovcnt = 1;
906 	auio.uio_offset = poffset;
907 	auio.uio_segflg = UIO_NOCOPY;
908 	auio.uio_rw = UIO_WRITE;
909 	auio.uio_resid = maxsize;
910 	auio.uio_procp = (struct proc *) 0;
911 	error = VOP_WRITE(vp, &auio, ioflags, curproc->p_ucred);
912 	cnt.v_vnodeout++;
913 	cnt.v_vnodepgsout += ncount;
914 
915 	if (error) {
916 		printf("vnode_pager_putpages: I/O error %d\n", error);
917 	}
918 	if (auio.uio_resid) {
919 		printf("vnode_pager_putpages: residual I/O %d at %lu\n",
920 		    auio.uio_resid, (u_long)m[0]->pindex);
921 	}
922 	for (i = 0; i < ncount; i++) {
923 		rtvals[i] = VM_PAGER_OK;
924 	}
925 	return rtvals[0];
926 }
927 
928 struct vnode *
929 vnode_pager_lock(object)
930 	vm_object_t object;
931 {
932 	struct proc *p = curproc;	/* XXX */
933 
934 	for (; object != NULL; object = object->backing_object) {
935 		if (object->type != OBJT_VNODE)
936 			continue;
937 		if (object->flags & OBJ_DEAD)
938 			return NULL;
939 
940 		while (vget(object->handle,
941 			LK_NOPAUSE | LK_SHARED | LK_RETRY | LK_CANRECURSE, p)) {
942 			if ((object->flags & OBJ_DEAD) || (object->type != OBJT_VNODE))
943 				return NULL;
944 			printf("vnode_pager_lock: retrying\n");
945 		}
946 		return object->handle;
947 	}
948 	return NULL;
949 }
950