xref: /freebsd/sys/vm/vnode_pager.c (revision a33774adb3e7e902ca1742227ee070b93d602fc8)
1 /*-
2  * SPDX-License-Identifier: BSD-4-Clause
3  *
4  * Copyright (c) 1990 University of Utah.
5  * Copyright (c) 1991 The Regents of the University of California.
6  * All rights reserved.
7  * Copyright (c) 1993, 1994 John S. Dyson
8  * Copyright (c) 1995, David Greenman
9  *
10  * This code is derived from software contributed to Berkeley by
11  * the Systems Programming Group of the University of Utah Computer
12  * Science Department.
13  *
14  * Redistribution and use in source and binary forms, with or without
15  * modification, are permitted provided that the following conditions
16  * are met:
17  * 1. Redistributions of source code must retain the above copyright
18  *    notice, this list of conditions and the following disclaimer.
19  * 2. Redistributions in binary form must reproduce the above copyright
20  *    notice, this list of conditions and the following disclaimer in the
21  *    documentation and/or other materials provided with the distribution.
22  * 3. All advertising materials mentioning features or use of this software
23  *    must display the following acknowledgement:
24  *	This product includes software developed by the University of
25  *	California, Berkeley and its contributors.
26  * 4. Neither the name of the University nor the names of its contributors
27  *    may be used to endorse or promote products derived from this software
28  *    without specific prior written permission.
29  *
30  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
31  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
32  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
33  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
34  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
35  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
36  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
37  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
38  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
39  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
40  * SUCH DAMAGE.
41  *
42  *	from: @(#)vnode_pager.c	7.5 (Berkeley) 4/20/91
43  */
44 
45 /*
46  * Page to/from files (vnodes).
47  */
48 
49 /*
50  * TODO:
51  *	Implement VOP_GETPAGES/PUTPAGES interface for filesystems. Will
52  *	greatly re-simplify the vnode_pager.
53  */
54 
55 #include <sys/cdefs.h>
56 __FBSDID("$FreeBSD$");
57 
58 #include "opt_vm.h"
59 
60 #include <sys/param.h>
61 #include <sys/kernel.h>
62 #include <sys/systm.h>
63 #include <sys/sysctl.h>
64 #include <sys/proc.h>
65 #include <sys/vnode.h>
66 #include <sys/mount.h>
67 #include <sys/bio.h>
68 #include <sys/buf.h>
69 #include <sys/vmmeter.h>
70 #include <sys/ktr.h>
71 #include <sys/limits.h>
72 #include <sys/conf.h>
73 #include <sys/refcount.h>
74 #include <sys/rwlock.h>
75 #include <sys/sf_buf.h>
76 #include <sys/domainset.h>
77 
78 #include <machine/atomic.h>
79 
80 #include <vm/vm.h>
81 #include <vm/vm_param.h>
82 #include <vm/vm_object.h>
83 #include <vm/vm_page.h>
84 #include <vm/vm_pager.h>
85 #include <vm/vm_map.h>
86 #include <vm/vnode_pager.h>
87 #include <vm/vm_extern.h>
88 #include <vm/uma.h>
89 
90 static int vnode_pager_addr(struct vnode *vp, vm_ooffset_t address,
91     daddr_t *rtaddress, int *run);
92 static int vnode_pager_input_smlfs(vm_object_t object, vm_page_t m);
93 static int vnode_pager_input_old(vm_object_t object, vm_page_t m);
94 static void vnode_pager_dealloc(vm_object_t);
95 static int vnode_pager_getpages(vm_object_t, vm_page_t *, int, int *, int *);
96 static int vnode_pager_getpages_async(vm_object_t, vm_page_t *, int, int *,
97     int *, vop_getpages_iodone_t, void *);
98 static void vnode_pager_putpages(vm_object_t, vm_page_t *, int, int, int *);
99 static boolean_t vnode_pager_haspage(vm_object_t, vm_pindex_t, int *, int *);
100 static vm_object_t vnode_pager_alloc(void *, vm_ooffset_t, vm_prot_t,
101     vm_ooffset_t, struct ucred *cred);
102 static int vnode_pager_generic_getpages_done(struct buf *);
103 static void vnode_pager_generic_getpages_done_async(struct buf *);
104 static void vnode_pager_update_writecount(vm_object_t, vm_offset_t,
105     vm_offset_t);
106 static void vnode_pager_release_writecount(vm_object_t, vm_offset_t,
107     vm_offset_t);
108 
109 struct pagerops vnodepagerops = {
110 	.pgo_alloc =	vnode_pager_alloc,
111 	.pgo_dealloc =	vnode_pager_dealloc,
112 	.pgo_getpages =	vnode_pager_getpages,
113 	.pgo_getpages_async = vnode_pager_getpages_async,
114 	.pgo_putpages =	vnode_pager_putpages,
115 	.pgo_haspage =	vnode_pager_haspage,
116 	.pgo_update_writecount = vnode_pager_update_writecount,
117 	.pgo_release_writecount = vnode_pager_release_writecount,
118 };
119 
120 static struct domainset *vnode_domainset = NULL;
121 
122 SYSCTL_PROC(_debug, OID_AUTO, vnode_domainset, CTLTYPE_STRING | CTLFLAG_RW,
123     &vnode_domainset, 0, sysctl_handle_domainset, "A",
124     "Default vnode NUMA policy");
125 
126 static int nvnpbufs;
127 SYSCTL_INT(_vm, OID_AUTO, vnode_pbufs, CTLFLAG_RDTUN | CTLFLAG_NOFETCH,
128     &nvnpbufs, 0, "number of physical buffers allocated for vnode pager");
129 
130 static uma_zone_t vnode_pbuf_zone;
131 
132 static void
133 vnode_pager_init(void *dummy)
134 {
135 
136 #ifdef __LP64__
137 	nvnpbufs = nswbuf * 2;
138 #else
139 	nvnpbufs = nswbuf / 2;
140 #endif
141 	TUNABLE_INT_FETCH("vm.vnode_pbufs", &nvnpbufs);
142 	vnode_pbuf_zone = pbuf_zsecond_create("vnpbuf", nvnpbufs);
143 }
144 SYSINIT(vnode_pager, SI_SUB_CPU, SI_ORDER_ANY, vnode_pager_init, NULL);
145 
146 /* Create the VM system backing object for this vnode */
147 int
148 vnode_create_vobject(struct vnode *vp, off_t isize, struct thread *td)
149 {
150 	vm_object_t object;
151 	vm_ooffset_t size = isize;
152 	struct vattr va;
153 	bool last;
154 
155 	if (!vn_isdisk(vp, NULL) && vn_canvmio(vp) == FALSE)
156 		return (0);
157 
158 	object = vp->v_object;
159 	if (object != NULL)
160 		return (0);
161 
162 	if (size == 0) {
163 		if (vn_isdisk(vp, NULL)) {
164 			size = IDX_TO_OFF(INT_MAX);
165 		} else {
166 			if (VOP_GETATTR(vp, &va, td->td_ucred))
167 				return (0);
168 			size = va.va_size;
169 		}
170 	}
171 
172 	object = vnode_pager_alloc(vp, size, 0, 0, td->td_ucred);
173 	/*
174 	 * Dereference the reference we just created.  This assumes
175 	 * that the object is associated with the vp.  We still have
176 	 * to serialize with vnode_pager_dealloc() for the last
177 	 * potential reference.
178 	 */
179 	VM_OBJECT_RLOCK(object);
180 	last = refcount_release(&object->ref_count);
181 	VM_OBJECT_RUNLOCK(object);
182 	if (last)
183 		vrele(vp);
184 
185 	KASSERT(vp->v_object != NULL, ("vnode_create_vobject: NULL object"));
186 
187 	return (0);
188 }
189 
190 void
191 vnode_destroy_vobject(struct vnode *vp)
192 {
193 	struct vm_object *obj;
194 
195 	obj = vp->v_object;
196 	if (obj == NULL || obj->handle != vp)
197 		return;
198 	ASSERT_VOP_ELOCKED(vp, "vnode_destroy_vobject");
199 	VM_OBJECT_WLOCK(obj);
200 	MPASS(obj->type == OBJT_VNODE);
201 	umtx_shm_object_terminated(obj);
202 	if (obj->ref_count == 0) {
203 		/*
204 		 * don't double-terminate the object
205 		 */
206 		if ((obj->flags & OBJ_DEAD) == 0) {
207 			vm_object_set_flag(obj, OBJ_DEAD);
208 
209 			/*
210 			 * Clean pages and flush buffers.
211 			 */
212 			vm_object_page_clean(obj, 0, 0, OBJPC_SYNC);
213 			VM_OBJECT_WUNLOCK(obj);
214 
215 			vinvalbuf(vp, V_SAVE, 0, 0);
216 
217 			BO_LOCK(&vp->v_bufobj);
218 			vp->v_bufobj.bo_flag |= BO_DEAD;
219 			BO_UNLOCK(&vp->v_bufobj);
220 
221 			VM_OBJECT_WLOCK(obj);
222 			vm_object_terminate(obj);
223 		} else {
224 			/*
225 			 * Waiters were already handled during object
226 			 * termination.  The exclusive vnode lock hopefully
227 			 * prevented new waiters from referencing the dying
228 			 * object.
229 			 */
230 			vp->v_object = NULL;
231 			VM_OBJECT_WUNLOCK(obj);
232 		}
233 	} else {
234 		/*
235 		 * Woe to the process that tries to page now :-).
236 		 */
237 		vm_pager_deallocate(obj);
238 		VM_OBJECT_WUNLOCK(obj);
239 	}
240 	KASSERT(vp->v_object == NULL, ("vp %p obj %p", vp, vp->v_object));
241 }
242 
243 
244 /*
245  * Allocate (or lookup) pager for a vnode.
246  * Handle is a vnode pointer.
247  */
248 vm_object_t
249 vnode_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
250     vm_ooffset_t offset, struct ucred *cred)
251 {
252 	vm_object_t object;
253 	struct vnode *vp;
254 
255 	/*
256 	 * Pageout to vnode, no can do yet.
257 	 */
258 	if (handle == NULL)
259 		return (NULL);
260 
261 	vp = (struct vnode *)handle;
262 	ASSERT_VOP_LOCKED(vp, "vnode_pager_alloc");
263 	KASSERT(vp->v_usecount != 0, ("vnode_pager_alloc: no vnode reference"));
264 retry:
265 	object = vp->v_object;
266 
267 	if (object == NULL) {
268 		/*
269 		 * Add an object of the appropriate size
270 		 */
271 		object = vm_object_allocate(OBJT_VNODE,
272 		    OFF_TO_IDX(round_page(size)));
273 
274 		object->un_pager.vnp.vnp_size = size;
275 		object->un_pager.vnp.writemappings = 0;
276 		object->domain.dr_policy = vnode_domainset;
277 		object->handle = handle;
278 		if ((vp->v_vflag & VV_VMSIZEVNLOCK) != 0) {
279 			VM_OBJECT_WLOCK(object);
280 			vm_object_set_flag(object, OBJ_SIZEVNLOCK);
281 			VM_OBJECT_WUNLOCK(object);
282 		}
283 		VI_LOCK(vp);
284 		if (vp->v_object != NULL) {
285 			/*
286 			 * Object has been created while we were allocating.
287 			 */
288 			VI_UNLOCK(vp);
289 			VM_OBJECT_WLOCK(object);
290 			KASSERT(object->ref_count == 1,
291 			    ("leaked ref %p %d", object, object->ref_count));
292 			object->type = OBJT_DEAD;
293 			refcount_init(&object->ref_count, 0);
294 			VM_OBJECT_WUNLOCK(object);
295 			vm_object_destroy(object);
296 			goto retry;
297 		}
298 		vp->v_object = object;
299 		VI_UNLOCK(vp);
300 		vrefact(vp);
301 	} else {
302 		vm_object_reference(object);
303 #if VM_NRESERVLEVEL > 0
304 		if ((object->flags & OBJ_COLORED) == 0) {
305 			VM_OBJECT_WLOCK(object);
306 			vm_object_color(object, 0);
307 			VM_OBJECT_WUNLOCK(object);
308 		}
309 #endif
310 	}
311 	return (object);
312 }
313 
314 /*
315  *	The object must be locked.
316  */
317 static void
318 vnode_pager_dealloc(vm_object_t object)
319 {
320 	struct vnode *vp;
321 	int refs;
322 
323 	vp = object->handle;
324 	if (vp == NULL)
325 		panic("vnode_pager_dealloc: pager already dealloced");
326 
327 	VM_OBJECT_ASSERT_WLOCKED(object);
328 	vm_object_pip_wait(object, "vnpdea");
329 	refs = object->ref_count;
330 
331 	object->handle = NULL;
332 	object->type = OBJT_DEAD;
333 	ASSERT_VOP_ELOCKED(vp, "vnode_pager_dealloc");
334 	if (object->un_pager.vnp.writemappings > 0) {
335 		object->un_pager.vnp.writemappings = 0;
336 		VOP_ADD_WRITECOUNT_CHECKED(vp, -1);
337 		CTR3(KTR_VFS, "%s: vp %p v_writecount decreased to %d",
338 		    __func__, vp, vp->v_writecount);
339 	}
340 	vp->v_object = NULL;
341 	VI_LOCK(vp);
342 
343 	/*
344 	 * vm_map_entry_set_vnode_text() cannot reach this vnode by
345 	 * following object->handle.  Clear all text references now.
346 	 * This also clears the transient references from
347 	 * kern_execve(), which is fine because dead_vnodeops uses nop
348 	 * for VOP_UNSET_TEXT().
349 	 */
350 	if (vp->v_writecount < 0)
351 		vp->v_writecount = 0;
352 	VI_UNLOCK(vp);
353 	VM_OBJECT_WUNLOCK(object);
354 	if (refs > 0)
355 		vunref(vp);
356 	VM_OBJECT_WLOCK(object);
357 }
358 
359 static boolean_t
360 vnode_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
361     int *after)
362 {
363 	struct vnode *vp = object->handle;
364 	daddr_t bn;
365 	uintptr_t lockstate;
366 	int err;
367 	daddr_t reqblock;
368 	int poff;
369 	int bsize;
370 	int pagesperblock, blocksperpage;
371 
372 	VM_OBJECT_ASSERT_LOCKED(object);
373 	/*
374 	 * If no vp or vp is doomed or marked transparent to VM, we do not
375 	 * have the page.
376 	 */
377 	if (vp == NULL || VN_IS_DOOMED(vp))
378 		return FALSE;
379 	/*
380 	 * If the offset is beyond end of file we do
381 	 * not have the page.
382 	 */
383 	if (IDX_TO_OFF(pindex) >= object->un_pager.vnp.vnp_size)
384 		return FALSE;
385 
386 	bsize = vp->v_mount->mnt_stat.f_iosize;
387 	pagesperblock = bsize / PAGE_SIZE;
388 	blocksperpage = 0;
389 	if (pagesperblock > 0) {
390 		reqblock = pindex / pagesperblock;
391 	} else {
392 		blocksperpage = (PAGE_SIZE / bsize);
393 		reqblock = pindex * blocksperpage;
394 	}
395 	lockstate = VM_OBJECT_DROP(object);
396 	err = VOP_BMAP(vp, reqblock, NULL, &bn, after, before);
397 	VM_OBJECT_PICKUP(object, lockstate);
398 	if (err)
399 		return TRUE;
400 	if (bn == -1)
401 		return FALSE;
402 	if (pagesperblock > 0) {
403 		poff = pindex - (reqblock * pagesperblock);
404 		if (before) {
405 			*before *= pagesperblock;
406 			*before += poff;
407 		}
408 		if (after) {
409 			/*
410 			 * The BMAP vop can report a partial block in the
411 			 * 'after', but must not report blocks after EOF.
412 			 * Assert the latter, and truncate 'after' in case
413 			 * of the former.
414 			 */
415 			KASSERT((reqblock + *after) * pagesperblock <
416 			    roundup2(object->size, pagesperblock),
417 			    ("%s: reqblock %jd after %d size %ju", __func__,
418 			    (intmax_t )reqblock, *after,
419 			    (uintmax_t )object->size));
420 			*after *= pagesperblock;
421 			*after += pagesperblock - (poff + 1);
422 			if (pindex + *after >= object->size)
423 				*after = object->size - 1 - pindex;
424 		}
425 	} else {
426 		if (before) {
427 			*before /= blocksperpage;
428 		}
429 
430 		if (after) {
431 			*after /= blocksperpage;
432 		}
433 	}
434 	return TRUE;
435 }
436 
437 /*
438  * Lets the VM system know about a change in size for a file.
439  * We adjust our own internal size and flush any cached pages in
440  * the associated object that are affected by the size change.
441  *
442  * Note: this routine may be invoked as a result of a pager put
443  * operation (possibly at object termination time), so we must be careful.
444  */
445 void
446 vnode_pager_setsize(struct vnode *vp, vm_ooffset_t nsize)
447 {
448 	vm_object_t object;
449 	vm_page_t m;
450 	vm_pindex_t nobjsize;
451 
452 	if ((object = vp->v_object) == NULL)
453 		return;
454 #ifdef DEBUG_VFS_LOCKS
455 	{
456 		struct mount *mp;
457 
458 		mp = vp->v_mount;
459 		if (mp != NULL && (mp->mnt_kern_flag & MNTK_VMSETSIZE_BUG) == 0)
460 			assert_vop_elocked(vp,
461 			    "vnode_pager_setsize and not locked vnode");
462 	}
463 #endif
464 	VM_OBJECT_WLOCK(object);
465 	if (object->type == OBJT_DEAD) {
466 		VM_OBJECT_WUNLOCK(object);
467 		return;
468 	}
469 	KASSERT(object->type == OBJT_VNODE,
470 	    ("not vnode-backed object %p", object));
471 	if (nsize == object->un_pager.vnp.vnp_size) {
472 		/*
473 		 * Hasn't changed size
474 		 */
475 		VM_OBJECT_WUNLOCK(object);
476 		return;
477 	}
478 	nobjsize = OFF_TO_IDX(nsize + PAGE_MASK);
479 	if (nsize < object->un_pager.vnp.vnp_size) {
480 		/*
481 		 * File has shrunk. Toss any cached pages beyond the new EOF.
482 		 */
483 		if (nobjsize < object->size)
484 			vm_object_page_remove(object, nobjsize, object->size,
485 			    0);
486 		/*
487 		 * this gets rid of garbage at the end of a page that is now
488 		 * only partially backed by the vnode.
489 		 *
490 		 * XXX for some reason (I don't know yet), if we take a
491 		 * completely invalid page and mark it partially valid
492 		 * it can screw up NFS reads, so we don't allow the case.
493 		 */
494 		if (!(nsize & PAGE_MASK))
495 			goto out;
496 		m = vm_page_grab(object, OFF_TO_IDX(nsize), VM_ALLOC_NOCREAT);
497 		if (m == NULL)
498 			goto out;
499 		if (!vm_page_none_valid(m)) {
500 			int base = (int)nsize & PAGE_MASK;
501 			int size = PAGE_SIZE - base;
502 
503 			/*
504 			 * Clear out partial-page garbage in case
505 			 * the page has been mapped.
506 			 */
507 			pmap_zero_page_area(m, base, size);
508 
509 			/*
510 			 * Update the valid bits to reflect the blocks that
511 			 * have been zeroed.  Some of these valid bits may
512 			 * have already been set.
513 			 */
514 			vm_page_set_valid_range(m, base, size);
515 
516 			/*
517 			 * Round "base" to the next block boundary so that the
518 			 * dirty bit for a partially zeroed block is not
519 			 * cleared.
520 			 */
521 			base = roundup2(base, DEV_BSIZE);
522 
523 			/*
524 			 * Clear out partial-page dirty bits.
525 			 *
526 			 * note that we do not clear out the valid
527 			 * bits.  This would prevent bogus_page
528 			 * replacement from working properly.
529 			 */
530 			vm_page_clear_dirty(m, base, PAGE_SIZE - base);
531 		}
532 		vm_page_xunbusy(m);
533 	}
534 out:
535 	object->un_pager.vnp.vnp_size = nsize;
536 	object->size = nobjsize;
537 	VM_OBJECT_WUNLOCK(object);
538 }
539 
540 /*
541  * calculate the linear (byte) disk address of specified virtual
542  * file address
543  */
544 static int
545 vnode_pager_addr(struct vnode *vp, vm_ooffset_t address, daddr_t *rtaddress,
546     int *run)
547 {
548 	int bsize;
549 	int err;
550 	daddr_t vblock;
551 	daddr_t voffset;
552 
553 	if (address < 0)
554 		return -1;
555 
556 	if (VN_IS_DOOMED(vp))
557 		return -1;
558 
559 	bsize = vp->v_mount->mnt_stat.f_iosize;
560 	vblock = address / bsize;
561 	voffset = address % bsize;
562 
563 	err = VOP_BMAP(vp, vblock, NULL, rtaddress, run, NULL);
564 	if (err == 0) {
565 		if (*rtaddress != -1)
566 			*rtaddress += voffset / DEV_BSIZE;
567 		if (run) {
568 			*run += 1;
569 			*run *= bsize / PAGE_SIZE;
570 			*run -= voffset / PAGE_SIZE;
571 		}
572 	}
573 
574 	return (err);
575 }
576 
577 /*
578  * small block filesystem vnode pager input
579  */
580 static int
581 vnode_pager_input_smlfs(vm_object_t object, vm_page_t m)
582 {
583 	struct vnode *vp;
584 	struct bufobj *bo;
585 	struct buf *bp;
586 	struct sf_buf *sf;
587 	daddr_t fileaddr;
588 	vm_offset_t bsize;
589 	vm_page_bits_t bits;
590 	int error, i;
591 
592 	error = 0;
593 	vp = object->handle;
594 	if (VN_IS_DOOMED(vp))
595 		return VM_PAGER_BAD;
596 
597 	bsize = vp->v_mount->mnt_stat.f_iosize;
598 
599 	VOP_BMAP(vp, 0, &bo, 0, NULL, NULL);
600 
601 	sf = sf_buf_alloc(m, 0);
602 
603 	for (i = 0; i < PAGE_SIZE / bsize; i++) {
604 		vm_ooffset_t address;
605 
606 		bits = vm_page_bits(i * bsize, bsize);
607 		if (m->valid & bits)
608 			continue;
609 
610 		address = IDX_TO_OFF(m->pindex) + i * bsize;
611 		if (address >= object->un_pager.vnp.vnp_size) {
612 			fileaddr = -1;
613 		} else {
614 			error = vnode_pager_addr(vp, address, &fileaddr, NULL);
615 			if (error)
616 				break;
617 		}
618 		if (fileaddr != -1) {
619 			bp = uma_zalloc(vnode_pbuf_zone, M_WAITOK);
620 
621 			/* build a minimal buffer header */
622 			bp->b_iocmd = BIO_READ;
623 			bp->b_iodone = bdone;
624 			KASSERT(bp->b_rcred == NOCRED, ("leaking read ucred"));
625 			KASSERT(bp->b_wcred == NOCRED, ("leaking write ucred"));
626 			bp->b_rcred = crhold(curthread->td_ucred);
627 			bp->b_wcred = crhold(curthread->td_ucred);
628 			bp->b_data = (caddr_t)sf_buf_kva(sf) + i * bsize;
629 			bp->b_blkno = fileaddr;
630 			pbgetbo(bo, bp);
631 			bp->b_vp = vp;
632 			bp->b_bcount = bsize;
633 			bp->b_bufsize = bsize;
634 			bp->b_runningbufspace = bp->b_bufsize;
635 			atomic_add_long(&runningbufspace, bp->b_runningbufspace);
636 
637 			/* do the input */
638 			bp->b_iooffset = dbtob(bp->b_blkno);
639 			bstrategy(bp);
640 
641 			bwait(bp, PVM, "vnsrd");
642 
643 			if ((bp->b_ioflags & BIO_ERROR) != 0)
644 				error = EIO;
645 
646 			/*
647 			 * free the buffer header back to the swap buffer pool
648 			 */
649 			bp->b_vp = NULL;
650 			pbrelbo(bp);
651 			uma_zfree(vnode_pbuf_zone, bp);
652 			if (error)
653 				break;
654 		} else
655 			bzero((caddr_t)sf_buf_kva(sf) + i * bsize, bsize);
656 		KASSERT((m->dirty & bits) == 0,
657 		    ("vnode_pager_input_smlfs: page %p is dirty", m));
658 		vm_page_bits_set(m, &m->valid, bits);
659 	}
660 	sf_buf_free(sf);
661 	if (error) {
662 		return VM_PAGER_ERROR;
663 	}
664 	return VM_PAGER_OK;
665 }
666 
667 /*
668  * old style vnode pager input routine
669  */
670 static int
671 vnode_pager_input_old(vm_object_t object, vm_page_t m)
672 {
673 	struct uio auio;
674 	struct iovec aiov;
675 	int error;
676 	int size;
677 	struct sf_buf *sf;
678 	struct vnode *vp;
679 
680 	VM_OBJECT_ASSERT_WLOCKED(object);
681 	error = 0;
682 
683 	/*
684 	 * Return failure if beyond current EOF
685 	 */
686 	if (IDX_TO_OFF(m->pindex) >= object->un_pager.vnp.vnp_size) {
687 		return VM_PAGER_BAD;
688 	} else {
689 		size = PAGE_SIZE;
690 		if (IDX_TO_OFF(m->pindex) + size > object->un_pager.vnp.vnp_size)
691 			size = object->un_pager.vnp.vnp_size - IDX_TO_OFF(m->pindex);
692 		vp = object->handle;
693 		VM_OBJECT_WUNLOCK(object);
694 
695 		/*
696 		 * Allocate a kernel virtual address and initialize so that
697 		 * we can use VOP_READ/WRITE routines.
698 		 */
699 		sf = sf_buf_alloc(m, 0);
700 
701 		aiov.iov_base = (caddr_t)sf_buf_kva(sf);
702 		aiov.iov_len = size;
703 		auio.uio_iov = &aiov;
704 		auio.uio_iovcnt = 1;
705 		auio.uio_offset = IDX_TO_OFF(m->pindex);
706 		auio.uio_segflg = UIO_SYSSPACE;
707 		auio.uio_rw = UIO_READ;
708 		auio.uio_resid = size;
709 		auio.uio_td = curthread;
710 
711 		error = VOP_READ(vp, &auio, 0, curthread->td_ucred);
712 		if (!error) {
713 			int count = size - auio.uio_resid;
714 
715 			if (count == 0)
716 				error = EINVAL;
717 			else if (count != PAGE_SIZE)
718 				bzero((caddr_t)sf_buf_kva(sf) + count,
719 				    PAGE_SIZE - count);
720 		}
721 		sf_buf_free(sf);
722 
723 		VM_OBJECT_WLOCK(object);
724 	}
725 	KASSERT(m->dirty == 0, ("vnode_pager_input_old: page %p is dirty", m));
726 	if (!error)
727 		vm_page_valid(m);
728 	return error ? VM_PAGER_ERROR : VM_PAGER_OK;
729 }
730 
731 /*
732  * generic vnode pager input routine
733  */
734 
735 /*
736  * Local media VFS's that do not implement their own VOP_GETPAGES
737  * should have their VOP_GETPAGES call to vnode_pager_generic_getpages()
738  * to implement the previous behaviour.
739  *
740  * All other FS's should use the bypass to get to the local media
741  * backing vp's VOP_GETPAGES.
742  */
743 static int
744 vnode_pager_getpages(vm_object_t object, vm_page_t *m, int count, int *rbehind,
745     int *rahead)
746 {
747 	struct vnode *vp;
748 	int rtval;
749 
750 	vp = object->handle;
751 	VM_OBJECT_WUNLOCK(object);
752 	rtval = VOP_GETPAGES(vp, m, count, rbehind, rahead);
753 	KASSERT(rtval != EOPNOTSUPP,
754 	    ("vnode_pager: FS getpages not implemented\n"));
755 	VM_OBJECT_WLOCK(object);
756 	return rtval;
757 }
758 
759 static int
760 vnode_pager_getpages_async(vm_object_t object, vm_page_t *m, int count,
761     int *rbehind, int *rahead, vop_getpages_iodone_t iodone, void *arg)
762 {
763 	struct vnode *vp;
764 	int rtval;
765 
766 	vp = object->handle;
767 	VM_OBJECT_WUNLOCK(object);
768 	rtval = VOP_GETPAGES_ASYNC(vp, m, count, rbehind, rahead, iodone, arg);
769 	KASSERT(rtval != EOPNOTSUPP,
770 	    ("vnode_pager: FS getpages_async not implemented\n"));
771 	VM_OBJECT_WLOCK(object);
772 	return (rtval);
773 }
774 
775 /*
776  * The implementation of VOP_GETPAGES() and VOP_GETPAGES_ASYNC() for
777  * local filesystems, where partially valid pages can only occur at
778  * the end of file.
779  */
780 int
781 vnode_pager_local_getpages(struct vop_getpages_args *ap)
782 {
783 
784 	return (vnode_pager_generic_getpages(ap->a_vp, ap->a_m, ap->a_count,
785 	    ap->a_rbehind, ap->a_rahead, NULL, NULL));
786 }
787 
788 int
789 vnode_pager_local_getpages_async(struct vop_getpages_async_args *ap)
790 {
791 
792 	return (vnode_pager_generic_getpages(ap->a_vp, ap->a_m, ap->a_count,
793 	    ap->a_rbehind, ap->a_rahead, ap->a_iodone, ap->a_arg));
794 }
795 
796 /*
797  * This is now called from local media FS's to operate against their
798  * own vnodes if they fail to implement VOP_GETPAGES.
799  */
800 int
801 vnode_pager_generic_getpages(struct vnode *vp, vm_page_t *m, int count,
802     int *a_rbehind, int *a_rahead, vop_getpages_iodone_t iodone, void *arg)
803 {
804 	vm_object_t object;
805 	struct bufobj *bo;
806 	struct buf *bp;
807 	off_t foff;
808 #ifdef INVARIANTS
809 	off_t blkno0;
810 #endif
811 	int bsize, pagesperblock;
812 	int error, before, after, rbehind, rahead, poff, i;
813 	int bytecount, secmask;
814 
815 	KASSERT(vp->v_type != VCHR && vp->v_type != VBLK,
816 	    ("%s does not support devices", __func__));
817 
818 	if (VN_IS_DOOMED(vp))
819 		return (VM_PAGER_BAD);
820 
821 	object = vp->v_object;
822 	foff = IDX_TO_OFF(m[0]->pindex);
823 	bsize = vp->v_mount->mnt_stat.f_iosize;
824 	pagesperblock = bsize / PAGE_SIZE;
825 
826 	KASSERT(foff < object->un_pager.vnp.vnp_size,
827 	    ("%s: page %p offset beyond vp %p size", __func__, m[0], vp));
828 	KASSERT(count <= nitems(bp->b_pages),
829 	    ("%s: requested %d pages", __func__, count));
830 
831 	/*
832 	 * The last page has valid blocks.  Invalid part can only
833 	 * exist at the end of file, and the page is made fully valid
834 	 * by zeroing in vm_pager_get_pages().
835 	 */
836 	if (!vm_page_none_valid(m[count - 1]) && --count == 0) {
837 		if (iodone != NULL)
838 			iodone(arg, m, 1, 0);
839 		return (VM_PAGER_OK);
840 	}
841 
842 	bp = uma_zalloc(vnode_pbuf_zone, M_WAITOK);
843 
844 	/*
845 	 * Get the underlying device blocks for the file with VOP_BMAP().
846 	 * If the file system doesn't support VOP_BMAP, use old way of
847 	 * getting pages via VOP_READ.
848 	 */
849 	error = VOP_BMAP(vp, foff / bsize, &bo, &bp->b_blkno, &after, &before);
850 	if (error == EOPNOTSUPP) {
851 		uma_zfree(vnode_pbuf_zone, bp);
852 		VM_OBJECT_WLOCK(object);
853 		for (i = 0; i < count; i++) {
854 			VM_CNT_INC(v_vnodein);
855 			VM_CNT_INC(v_vnodepgsin);
856 			error = vnode_pager_input_old(object, m[i]);
857 			if (error)
858 				break;
859 		}
860 		VM_OBJECT_WUNLOCK(object);
861 		return (error);
862 	} else if (error != 0) {
863 		uma_zfree(vnode_pbuf_zone, bp);
864 		return (VM_PAGER_ERROR);
865 	}
866 
867 	/*
868 	 * If the file system supports BMAP, but blocksize is smaller
869 	 * than a page size, then use special small filesystem code.
870 	 */
871 	if (pagesperblock == 0) {
872 		uma_zfree(vnode_pbuf_zone, bp);
873 		for (i = 0; i < count; i++) {
874 			VM_CNT_INC(v_vnodein);
875 			VM_CNT_INC(v_vnodepgsin);
876 			error = vnode_pager_input_smlfs(object, m[i]);
877 			if (error)
878 				break;
879 		}
880 		return (error);
881 	}
882 
883 	/*
884 	 * A sparse file can be encountered only for a single page request,
885 	 * which may not be preceded by call to vm_pager_haspage().
886 	 */
887 	if (bp->b_blkno == -1) {
888 		KASSERT(count == 1,
889 		    ("%s: array[%d] request to a sparse file %p", __func__,
890 		    count, vp));
891 		uma_zfree(vnode_pbuf_zone, bp);
892 		pmap_zero_page(m[0]);
893 		KASSERT(m[0]->dirty == 0, ("%s: page %p is dirty",
894 		    __func__, m[0]));
895 		vm_page_valid(m[0]);
896 		return (VM_PAGER_OK);
897 	}
898 
899 #ifdef INVARIANTS
900 	blkno0 = bp->b_blkno;
901 #endif
902 	bp->b_blkno += (foff % bsize) / DEV_BSIZE;
903 
904 	/* Recalculate blocks available after/before to pages. */
905 	poff = (foff % bsize) / PAGE_SIZE;
906 	before *= pagesperblock;
907 	before += poff;
908 	after *= pagesperblock;
909 	after += pagesperblock - (poff + 1);
910 	if (m[0]->pindex + after >= object->size)
911 		after = object->size - 1 - m[0]->pindex;
912 	KASSERT(count <= after + 1, ("%s: %d pages asked, can do only %d",
913 	    __func__, count, after + 1));
914 	after -= count - 1;
915 
916 	/* Trim requested rbehind/rahead to possible values. */
917 	rbehind = a_rbehind ? *a_rbehind : 0;
918 	rahead = a_rahead ? *a_rahead : 0;
919 	rbehind = min(rbehind, before);
920 	rbehind = min(rbehind, m[0]->pindex);
921 	rahead = min(rahead, after);
922 	rahead = min(rahead, object->size - m[count - 1]->pindex);
923 	/*
924 	 * Check that total amount of pages fit into buf.  Trim rbehind and
925 	 * rahead evenly if not.
926 	 */
927 	if (rbehind + rahead + count > nitems(bp->b_pages)) {
928 		int trim, sum;
929 
930 		trim = rbehind + rahead + count - nitems(bp->b_pages) + 1;
931 		sum = rbehind + rahead;
932 		if (rbehind == before) {
933 			/* Roundup rbehind trim to block size. */
934 			rbehind -= roundup(trim * rbehind / sum, pagesperblock);
935 			if (rbehind < 0)
936 				rbehind = 0;
937 		} else
938 			rbehind -= trim * rbehind / sum;
939 		rahead -= trim * rahead / sum;
940 	}
941 	KASSERT(rbehind + rahead + count <= nitems(bp->b_pages),
942 	    ("%s: behind %d ahead %d count %d", __func__,
943 	    rbehind, rahead, count));
944 
945 	/*
946 	 * Fill in the bp->b_pages[] array with requested and optional
947 	 * read behind or read ahead pages.  Read behind pages are looked
948 	 * up in a backward direction, down to a first cached page.  Same
949 	 * for read ahead pages, but there is no need to shift the array
950 	 * in case of encountering a cached page.
951 	 */
952 	i = bp->b_npages = 0;
953 	if (rbehind) {
954 		vm_pindex_t startpindex, tpindex;
955 		vm_page_t p;
956 
957 		VM_OBJECT_WLOCK(object);
958 		startpindex = m[0]->pindex - rbehind;
959 		if ((p = TAILQ_PREV(m[0], pglist, listq)) != NULL &&
960 		    p->pindex >= startpindex)
961 			startpindex = p->pindex + 1;
962 
963 		/* tpindex is unsigned; beware of numeric underflow. */
964 		for (tpindex = m[0]->pindex - 1;
965 		    tpindex >= startpindex && tpindex < m[0]->pindex;
966 		    tpindex--, i++) {
967 			p = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL);
968 			if (p == NULL) {
969 				/* Shift the array. */
970 				for (int j = 0; j < i; j++)
971 					bp->b_pages[j] = bp->b_pages[j +
972 					    tpindex + 1 - startpindex];
973 				break;
974 			}
975 			bp->b_pages[tpindex - startpindex] = p;
976 		}
977 
978 		bp->b_pgbefore = i;
979 		bp->b_npages += i;
980 		bp->b_blkno -= IDX_TO_OFF(i) / DEV_BSIZE;
981 	} else
982 		bp->b_pgbefore = 0;
983 
984 	/* Requested pages. */
985 	for (int j = 0; j < count; j++, i++)
986 		bp->b_pages[i] = m[j];
987 	bp->b_npages += count;
988 
989 	if (rahead) {
990 		vm_pindex_t endpindex, tpindex;
991 		vm_page_t p;
992 
993 		if (!VM_OBJECT_WOWNED(object))
994 			VM_OBJECT_WLOCK(object);
995 		endpindex = m[count - 1]->pindex + rahead + 1;
996 		if ((p = TAILQ_NEXT(m[count - 1], listq)) != NULL &&
997 		    p->pindex < endpindex)
998 			endpindex = p->pindex;
999 		if (endpindex > object->size)
1000 			endpindex = object->size;
1001 
1002 		for (tpindex = m[count - 1]->pindex + 1;
1003 		    tpindex < endpindex; i++, tpindex++) {
1004 			p = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL);
1005 			if (p == NULL)
1006 				break;
1007 			bp->b_pages[i] = p;
1008 		}
1009 
1010 		bp->b_pgafter = i - bp->b_npages;
1011 		bp->b_npages = i;
1012 	} else
1013 		bp->b_pgafter = 0;
1014 
1015 	if (VM_OBJECT_WOWNED(object))
1016 		VM_OBJECT_WUNLOCK(object);
1017 
1018 	/* Report back actual behind/ahead read. */
1019 	if (a_rbehind)
1020 		*a_rbehind = bp->b_pgbefore;
1021 	if (a_rahead)
1022 		*a_rahead = bp->b_pgafter;
1023 
1024 #ifdef INVARIANTS
1025 	KASSERT(bp->b_npages <= nitems(bp->b_pages),
1026 	    ("%s: buf %p overflowed", __func__, bp));
1027 	for (int j = 1, prev = 0; j < bp->b_npages; j++) {
1028 		if (bp->b_pages[j] == bogus_page)
1029 			continue;
1030 		KASSERT(bp->b_pages[j]->pindex - bp->b_pages[prev]->pindex ==
1031 		    j - prev, ("%s: pages array not consecutive, bp %p",
1032 		     __func__, bp));
1033 		prev = j;
1034 	}
1035 #endif
1036 
1037 	/*
1038 	 * Recalculate first offset and bytecount with regards to read behind.
1039 	 * Truncate bytecount to vnode real size and round up physical size
1040 	 * for real devices.
1041 	 */
1042 	foff = IDX_TO_OFF(bp->b_pages[0]->pindex);
1043 	bytecount = bp->b_npages << PAGE_SHIFT;
1044 	if ((foff + bytecount) > object->un_pager.vnp.vnp_size)
1045 		bytecount = object->un_pager.vnp.vnp_size - foff;
1046 	secmask = bo->bo_bsize - 1;
1047 	KASSERT(secmask < PAGE_SIZE && secmask > 0,
1048 	    ("%s: sector size %d too large", __func__, secmask + 1));
1049 	bytecount = (bytecount + secmask) & ~secmask;
1050 
1051 	/*
1052 	 * And map the pages to be read into the kva, if the filesystem
1053 	 * requires mapped buffers.
1054 	 */
1055 	if ((vp->v_mount->mnt_kern_flag & MNTK_UNMAPPED_BUFS) != 0 &&
1056 	    unmapped_buf_allowed) {
1057 		bp->b_data = unmapped_buf;
1058 		bp->b_offset = 0;
1059 	} else {
1060 		bp->b_data = bp->b_kvabase;
1061 		pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages);
1062 	}
1063 
1064 	/* Build a minimal buffer header. */
1065 	bp->b_iocmd = BIO_READ;
1066 	KASSERT(bp->b_rcred == NOCRED, ("leaking read ucred"));
1067 	KASSERT(bp->b_wcred == NOCRED, ("leaking write ucred"));
1068 	bp->b_rcred = crhold(curthread->td_ucred);
1069 	bp->b_wcred = crhold(curthread->td_ucred);
1070 	pbgetbo(bo, bp);
1071 	bp->b_vp = vp;
1072 	bp->b_bcount = bp->b_bufsize = bp->b_runningbufspace = bytecount;
1073 	bp->b_iooffset = dbtob(bp->b_blkno);
1074 	KASSERT(IDX_TO_OFF(m[0]->pindex - bp->b_pages[0]->pindex) ==
1075 	    (blkno0 - bp->b_blkno) * DEV_BSIZE +
1076 	    IDX_TO_OFF(m[0]->pindex) % bsize,
1077 	    ("wrong offsets bsize %d m[0] %ju b_pages[0] %ju "
1078 	    "blkno0 %ju b_blkno %ju", bsize,
1079 	    (uintmax_t)m[0]->pindex, (uintmax_t)bp->b_pages[0]->pindex,
1080 	    (uintmax_t)blkno0, (uintmax_t)bp->b_blkno));
1081 
1082 	atomic_add_long(&runningbufspace, bp->b_runningbufspace);
1083 	VM_CNT_INC(v_vnodein);
1084 	VM_CNT_ADD(v_vnodepgsin, bp->b_npages);
1085 
1086 	if (iodone != NULL) { /* async */
1087 		bp->b_pgiodone = iodone;
1088 		bp->b_caller1 = arg;
1089 		bp->b_iodone = vnode_pager_generic_getpages_done_async;
1090 		bp->b_flags |= B_ASYNC;
1091 		BUF_KERNPROC(bp);
1092 		bstrategy(bp);
1093 		return (VM_PAGER_OK);
1094 	} else {
1095 		bp->b_iodone = bdone;
1096 		bstrategy(bp);
1097 		bwait(bp, PVM, "vnread");
1098 		error = vnode_pager_generic_getpages_done(bp);
1099 		for (i = 0; i < bp->b_npages; i++)
1100 			bp->b_pages[i] = NULL;
1101 		bp->b_vp = NULL;
1102 		pbrelbo(bp);
1103 		uma_zfree(vnode_pbuf_zone, bp);
1104 		return (error != 0 ? VM_PAGER_ERROR : VM_PAGER_OK);
1105 	}
1106 }
1107 
1108 static void
1109 vnode_pager_generic_getpages_done_async(struct buf *bp)
1110 {
1111 	int error;
1112 
1113 	error = vnode_pager_generic_getpages_done(bp);
1114 	/* Run the iodone upon the requested range. */
1115 	bp->b_pgiodone(bp->b_caller1, bp->b_pages + bp->b_pgbefore,
1116 	    bp->b_npages - bp->b_pgbefore - bp->b_pgafter, error);
1117 	for (int i = 0; i < bp->b_npages; i++)
1118 		bp->b_pages[i] = NULL;
1119 	bp->b_vp = NULL;
1120 	pbrelbo(bp);
1121 	uma_zfree(vnode_pbuf_zone, bp);
1122 }
1123 
1124 static int
1125 vnode_pager_generic_getpages_done(struct buf *bp)
1126 {
1127 	vm_object_t object;
1128 	off_t tfoff, nextoff;
1129 	int i, error;
1130 
1131 	error = (bp->b_ioflags & BIO_ERROR) != 0 ? EIO : 0;
1132 	object = bp->b_vp->v_object;
1133 
1134 	if (error == 0 && bp->b_bcount != bp->b_npages * PAGE_SIZE) {
1135 		if (!buf_mapped(bp)) {
1136 			bp->b_data = bp->b_kvabase;
1137 			pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages,
1138 			    bp->b_npages);
1139 		}
1140 		bzero(bp->b_data + bp->b_bcount,
1141 		    PAGE_SIZE * bp->b_npages - bp->b_bcount);
1142 	}
1143 	if (buf_mapped(bp)) {
1144 		pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages);
1145 		bp->b_data = unmapped_buf;
1146 	}
1147 
1148 	/* Read lock to protect size. */
1149 	VM_OBJECT_RLOCK(object);
1150 	for (i = 0, tfoff = IDX_TO_OFF(bp->b_pages[0]->pindex);
1151 	    i < bp->b_npages; i++, tfoff = nextoff) {
1152 		vm_page_t mt;
1153 
1154 		nextoff = tfoff + PAGE_SIZE;
1155 		mt = bp->b_pages[i];
1156 		if (mt == bogus_page)
1157 			continue;
1158 
1159 		if (nextoff <= object->un_pager.vnp.vnp_size) {
1160 			/*
1161 			 * Read filled up entire page.
1162 			 */
1163 			vm_page_valid(mt);
1164 			KASSERT(mt->dirty == 0,
1165 			    ("%s: page %p is dirty", __func__, mt));
1166 			KASSERT(!pmap_page_is_mapped(mt),
1167 			    ("%s: page %p is mapped", __func__, mt));
1168 		} else {
1169 			/*
1170 			 * Read did not fill up entire page.
1171 			 *
1172 			 * Currently we do not set the entire page valid,
1173 			 * we just try to clear the piece that we couldn't
1174 			 * read.
1175 			 */
1176 			vm_page_set_valid_range(mt, 0,
1177 			    object->un_pager.vnp.vnp_size - tfoff);
1178 			KASSERT((mt->dirty & vm_page_bits(0,
1179 			    object->un_pager.vnp.vnp_size - tfoff)) == 0,
1180 			    ("%s: page %p is dirty", __func__, mt));
1181 		}
1182 
1183 		if (i < bp->b_pgbefore || i >= bp->b_npages - bp->b_pgafter)
1184 			vm_page_readahead_finish(mt);
1185 	}
1186 	VM_OBJECT_RUNLOCK(object);
1187 	if (error != 0)
1188 		printf("%s: I/O read error %d\n", __func__, error);
1189 
1190 	return (error);
1191 }
1192 
1193 /*
1194  * EOPNOTSUPP is no longer legal.  For local media VFS's that do not
1195  * implement their own VOP_PUTPAGES, their VOP_PUTPAGES should call to
1196  * vnode_pager_generic_putpages() to implement the previous behaviour.
1197  *
1198  * All other FS's should use the bypass to get to the local media
1199  * backing vp's VOP_PUTPAGES.
1200  */
1201 static void
1202 vnode_pager_putpages(vm_object_t object, vm_page_t *m, int count,
1203     int flags, int *rtvals)
1204 {
1205 	int rtval;
1206 	struct vnode *vp;
1207 	int bytes = count * PAGE_SIZE;
1208 
1209 	/*
1210 	 * Force synchronous operation if we are extremely low on memory
1211 	 * to prevent a low-memory deadlock.  VOP operations often need to
1212 	 * allocate more memory to initiate the I/O ( i.e. do a BMAP
1213 	 * operation ).  The swapper handles the case by limiting the amount
1214 	 * of asynchronous I/O, but that sort of solution doesn't scale well
1215 	 * for the vnode pager without a lot of work.
1216 	 *
1217 	 * Also, the backing vnode's iodone routine may not wake the pageout
1218 	 * daemon up.  This should be probably be addressed XXX.
1219 	 */
1220 
1221 	if (vm_page_count_min())
1222 		flags |= VM_PAGER_PUT_SYNC;
1223 
1224 	/*
1225 	 * Call device-specific putpages function
1226 	 */
1227 	vp = object->handle;
1228 	VM_OBJECT_WUNLOCK(object);
1229 	rtval = VOP_PUTPAGES(vp, m, bytes, flags, rtvals);
1230 	KASSERT(rtval != EOPNOTSUPP,
1231 	    ("vnode_pager: stale FS putpages\n"));
1232 	VM_OBJECT_WLOCK(object);
1233 }
1234 
1235 static int
1236 vn_off2bidx(vm_ooffset_t offset)
1237 {
1238 
1239 	return ((offset & PAGE_MASK) / DEV_BSIZE);
1240 }
1241 
1242 static bool
1243 vn_dirty_blk(vm_page_t m, vm_ooffset_t offset)
1244 {
1245 
1246 	KASSERT(IDX_TO_OFF(m->pindex) <= offset &&
1247 	    offset < IDX_TO_OFF(m->pindex + 1),
1248 	    ("page %p pidx %ju offset %ju", m, (uintmax_t)m->pindex,
1249 	    (uintmax_t)offset));
1250 	return ((m->dirty & ((vm_page_bits_t)1 << vn_off2bidx(offset))) != 0);
1251 }
1252 
1253 /*
1254  * This is now called from local media FS's to operate against their
1255  * own vnodes if they fail to implement VOP_PUTPAGES.
1256  *
1257  * This is typically called indirectly via the pageout daemon and
1258  * clustering has already typically occurred, so in general we ask the
1259  * underlying filesystem to write the data out asynchronously rather
1260  * then delayed.
1261  */
1262 int
1263 vnode_pager_generic_putpages(struct vnode *vp, vm_page_t *ma, int bytecount,
1264     int flags, int *rtvals)
1265 {
1266 	vm_object_t object;
1267 	vm_page_t m;
1268 	vm_ooffset_t maxblksz, next_offset, poffset, prev_offset;
1269 	struct uio auio;
1270 	struct iovec aiov;
1271 	off_t prev_resid, wrsz;
1272 	int count, error, i, maxsize, ncount, pgoff, ppscheck;
1273 	bool in_hole;
1274 	static struct timeval lastfail;
1275 	static int curfail;
1276 
1277 	object = vp->v_object;
1278 	count = bytecount / PAGE_SIZE;
1279 
1280 	for (i = 0; i < count; i++)
1281 		rtvals[i] = VM_PAGER_ERROR;
1282 
1283 	if ((int64_t)ma[0]->pindex < 0) {
1284 		printf("vnode_pager_generic_putpages: "
1285 		    "attempt to write meta-data 0x%jx(%lx)\n",
1286 		    (uintmax_t)ma[0]->pindex, (u_long)ma[0]->dirty);
1287 		rtvals[0] = VM_PAGER_BAD;
1288 		return (VM_PAGER_BAD);
1289 	}
1290 
1291 	maxsize = count * PAGE_SIZE;
1292 	ncount = count;
1293 
1294 	poffset = IDX_TO_OFF(ma[0]->pindex);
1295 
1296 	/*
1297 	 * If the page-aligned write is larger then the actual file we
1298 	 * have to invalidate pages occurring beyond the file EOF.  However,
1299 	 * there is an edge case where a file may not be page-aligned where
1300 	 * the last page is partially invalid.  In this case the filesystem
1301 	 * may not properly clear the dirty bits for the entire page (which
1302 	 * could be VM_PAGE_BITS_ALL due to the page having been mmap()d).
1303 	 * With the page locked we are free to fix-up the dirty bits here.
1304 	 *
1305 	 * We do not under any circumstances truncate the valid bits, as
1306 	 * this will screw up bogus page replacement.
1307 	 */
1308 	VM_OBJECT_RLOCK(object);
1309 	if (maxsize + poffset > object->un_pager.vnp.vnp_size) {
1310 		if (object->un_pager.vnp.vnp_size > poffset) {
1311 			maxsize = object->un_pager.vnp.vnp_size - poffset;
1312 			ncount = btoc(maxsize);
1313 			if ((pgoff = (int)maxsize & PAGE_MASK) != 0) {
1314 				pgoff = roundup2(pgoff, DEV_BSIZE);
1315 
1316 				/*
1317 				 * If the page is busy and the following
1318 				 * conditions hold, then the page's dirty
1319 				 * field cannot be concurrently changed by a
1320 				 * pmap operation.
1321 				 */
1322 				m = ma[ncount - 1];
1323 				vm_page_assert_sbusied(m);
1324 				KASSERT(!pmap_page_is_write_mapped(m),
1325 		("vnode_pager_generic_putpages: page %p is not read-only", m));
1326 				MPASS(m->dirty != 0);
1327 				vm_page_clear_dirty(m, pgoff, PAGE_SIZE -
1328 				    pgoff);
1329 			}
1330 		} else {
1331 			maxsize = 0;
1332 			ncount = 0;
1333 		}
1334 		for (i = ncount; i < count; i++)
1335 			rtvals[i] = VM_PAGER_BAD;
1336 	}
1337 	VM_OBJECT_RUNLOCK(object);
1338 
1339 	auio.uio_iov = &aiov;
1340 	auio.uio_segflg = UIO_NOCOPY;
1341 	auio.uio_rw = UIO_WRITE;
1342 	auio.uio_td = NULL;
1343 	maxblksz = roundup2(poffset + maxsize, DEV_BSIZE);
1344 
1345 	for (prev_offset = poffset; prev_offset < maxblksz;) {
1346 		/* Skip clean blocks. */
1347 		for (in_hole = true; in_hole && prev_offset < maxblksz;) {
1348 			m = ma[OFF_TO_IDX(prev_offset - poffset)];
1349 			for (i = vn_off2bidx(prev_offset);
1350 			    i < sizeof(vm_page_bits_t) * NBBY &&
1351 			    prev_offset < maxblksz; i++) {
1352 				if (vn_dirty_blk(m, prev_offset)) {
1353 					in_hole = false;
1354 					break;
1355 				}
1356 				prev_offset += DEV_BSIZE;
1357 			}
1358 		}
1359 		if (in_hole)
1360 			goto write_done;
1361 
1362 		/* Find longest run of dirty blocks. */
1363 		for (next_offset = prev_offset; next_offset < maxblksz;) {
1364 			m = ma[OFF_TO_IDX(next_offset - poffset)];
1365 			for (i = vn_off2bidx(next_offset);
1366 			    i < sizeof(vm_page_bits_t) * NBBY &&
1367 			    next_offset < maxblksz; i++) {
1368 				if (!vn_dirty_blk(m, next_offset))
1369 					goto start_write;
1370 				next_offset += DEV_BSIZE;
1371 			}
1372 		}
1373 start_write:
1374 		if (next_offset > poffset + maxsize)
1375 			next_offset = poffset + maxsize;
1376 
1377 		/*
1378 		 * Getting here requires finding a dirty block in the
1379 		 * 'skip clean blocks' loop.
1380 		 */
1381 		MPASS(prev_offset < next_offset);
1382 
1383 		aiov.iov_base = NULL;
1384 		auio.uio_iovcnt = 1;
1385 		auio.uio_offset = prev_offset;
1386 		prev_resid = auio.uio_resid = aiov.iov_len = next_offset -
1387 		    prev_offset;
1388 		error = VOP_WRITE(vp, &auio,
1389 		    vnode_pager_putpages_ioflags(flags), curthread->td_ucred);
1390 
1391 		wrsz = prev_resid - auio.uio_resid;
1392 		if (wrsz == 0) {
1393 			if (ppsratecheck(&lastfail, &curfail, 1) != 0) {
1394 				vn_printf(vp, "vnode_pager_putpages: "
1395 				    "zero-length write at %ju resid %zd\n",
1396 				    auio.uio_offset, auio.uio_resid);
1397 			}
1398 			break;
1399 		}
1400 
1401 		/* Adjust the starting offset for next iteration. */
1402 		prev_offset += wrsz;
1403 		MPASS(auio.uio_offset == prev_offset);
1404 
1405 		ppscheck = 0;
1406 		if (error != 0 && (ppscheck = ppsratecheck(&lastfail,
1407 		    &curfail, 1)) != 0)
1408 			vn_printf(vp, "vnode_pager_putpages: I/O error %d\n",
1409 			    error);
1410 		if (auio.uio_resid != 0 && (ppscheck != 0 ||
1411 		    ppsratecheck(&lastfail, &curfail, 1) != 0))
1412 			vn_printf(vp, "vnode_pager_putpages: residual I/O %zd "
1413 			    "at %ju\n", auio.uio_resid,
1414 			    (uintmax_t)ma[0]->pindex);
1415 		if (error != 0 || auio.uio_resid != 0)
1416 			break;
1417 	}
1418 write_done:
1419 	/* Mark completely processed pages. */
1420 	for (i = 0; i < OFF_TO_IDX(prev_offset - poffset); i++)
1421 		rtvals[i] = VM_PAGER_OK;
1422 	/* Mark partial EOF page. */
1423 	if (prev_offset == poffset + maxsize && (prev_offset & PAGE_MASK) != 0)
1424 		rtvals[i++] = VM_PAGER_OK;
1425 	/* Unwritten pages in range, free bonus if the page is clean. */
1426 	for (; i < ncount; i++)
1427 		rtvals[i] = ma[i]->dirty == 0 ? VM_PAGER_OK : VM_PAGER_ERROR;
1428 	VM_CNT_ADD(v_vnodepgsout, i);
1429 	VM_CNT_INC(v_vnodeout);
1430 	return (rtvals[0]);
1431 }
1432 
1433 int
1434 vnode_pager_putpages_ioflags(int pager_flags)
1435 {
1436 	int ioflags;
1437 
1438 	/*
1439 	 * Pageouts are already clustered, use IO_ASYNC to force a
1440 	 * bawrite() rather then a bdwrite() to prevent paging I/O
1441 	 * from saturating the buffer cache.  Dummy-up the sequential
1442 	 * heuristic to cause large ranges to cluster.  If neither
1443 	 * IO_SYNC or IO_ASYNC is set, the system decides how to
1444 	 * cluster.
1445 	 */
1446 	ioflags = IO_VMIO;
1447 	if ((pager_flags & (VM_PAGER_PUT_SYNC | VM_PAGER_PUT_INVAL)) != 0)
1448 		ioflags |= IO_SYNC;
1449 	else if ((pager_flags & VM_PAGER_CLUSTER_OK) == 0)
1450 		ioflags |= IO_ASYNC;
1451 	ioflags |= (pager_flags & VM_PAGER_PUT_INVAL) != 0 ? IO_INVAL: 0;
1452 	ioflags |= (pager_flags & VM_PAGER_PUT_NOREUSE) != 0 ? IO_NOREUSE : 0;
1453 	ioflags |= IO_SEQMAX << IO_SEQSHIFT;
1454 	return (ioflags);
1455 }
1456 
1457 /*
1458  * vnode_pager_undirty_pages().
1459  *
1460  * A helper to mark pages as clean after pageout that was possibly
1461  * done with a short write.  The lpos argument specifies the page run
1462  * length in bytes, and the written argument specifies how many bytes
1463  * were actually written.  eof is the offset past the last valid byte
1464  * in the vnode using the absolute file position of the first byte in
1465  * the run as the base from which it is computed.
1466  */
1467 void
1468 vnode_pager_undirty_pages(vm_page_t *ma, int *rtvals, int written, off_t eof,
1469     int lpos)
1470 {
1471 	vm_object_t obj;
1472 	int i, pos, pos_devb;
1473 
1474 	if (written == 0 && eof >= lpos)
1475 		return;
1476 	obj = ma[0]->object;
1477 	for (i = 0, pos = 0; pos < written; i++, pos += PAGE_SIZE) {
1478 		if (pos < trunc_page(written)) {
1479 			rtvals[i] = VM_PAGER_OK;
1480 			vm_page_undirty(ma[i]);
1481 		} else {
1482 			/* Partially written page. */
1483 			rtvals[i] = VM_PAGER_AGAIN;
1484 			vm_page_clear_dirty(ma[i], 0, written & PAGE_MASK);
1485 		}
1486 	}
1487 	if (eof >= lpos) /* avoid truncation */
1488 		return;
1489 	for (pos = eof, i = OFF_TO_IDX(trunc_page(pos)); pos < lpos; i++) {
1490 		if (pos != trunc_page(pos)) {
1491 			/*
1492 			 * The page contains the last valid byte in
1493 			 * the vnode, mark the rest of the page as
1494 			 * clean, potentially making the whole page
1495 			 * clean.
1496 			 */
1497 			pos_devb = roundup2(pos & PAGE_MASK, DEV_BSIZE);
1498 			vm_page_clear_dirty(ma[i], pos_devb, PAGE_SIZE -
1499 			    pos_devb);
1500 
1501 			/*
1502 			 * If the page was cleaned, report the pageout
1503 			 * on it as successful.  msync() no longer
1504 			 * needs to write out the page, endlessly
1505 			 * creating write requests and dirty buffers.
1506 			 */
1507 			if (ma[i]->dirty == 0)
1508 				rtvals[i] = VM_PAGER_OK;
1509 
1510 			pos = round_page(pos);
1511 		} else {
1512 			/* vm_pageout_flush() clears dirty */
1513 			rtvals[i] = VM_PAGER_BAD;
1514 			pos += PAGE_SIZE;
1515 		}
1516 	}
1517 }
1518 
1519 static void
1520 vnode_pager_update_writecount(vm_object_t object, vm_offset_t start,
1521     vm_offset_t end)
1522 {
1523 	struct vnode *vp;
1524 	vm_ooffset_t old_wm;
1525 
1526 	VM_OBJECT_WLOCK(object);
1527 	if (object->type != OBJT_VNODE) {
1528 		VM_OBJECT_WUNLOCK(object);
1529 		return;
1530 	}
1531 	old_wm = object->un_pager.vnp.writemappings;
1532 	object->un_pager.vnp.writemappings += (vm_ooffset_t)end - start;
1533 	vp = object->handle;
1534 	if (old_wm == 0 && object->un_pager.vnp.writemappings != 0) {
1535 		ASSERT_VOP_LOCKED(vp, "v_writecount inc");
1536 		VOP_ADD_WRITECOUNT_CHECKED(vp, 1);
1537 		CTR3(KTR_VFS, "%s: vp %p v_writecount increased to %d",
1538 		    __func__, vp, vp->v_writecount);
1539 	} else if (old_wm != 0 && object->un_pager.vnp.writemappings == 0) {
1540 		ASSERT_VOP_LOCKED(vp, "v_writecount dec");
1541 		VOP_ADD_WRITECOUNT_CHECKED(vp, -1);
1542 		CTR3(KTR_VFS, "%s: vp %p v_writecount decreased to %d",
1543 		    __func__, vp, vp->v_writecount);
1544 	}
1545 	VM_OBJECT_WUNLOCK(object);
1546 }
1547 
1548 static void
1549 vnode_pager_release_writecount(vm_object_t object, vm_offset_t start,
1550     vm_offset_t end)
1551 {
1552 	struct vnode *vp;
1553 	struct mount *mp;
1554 	vm_offset_t inc;
1555 
1556 	VM_OBJECT_WLOCK(object);
1557 
1558 	/*
1559 	 * First, recheck the object type to account for the race when
1560 	 * the vnode is reclaimed.
1561 	 */
1562 	if (object->type != OBJT_VNODE) {
1563 		VM_OBJECT_WUNLOCK(object);
1564 		return;
1565 	}
1566 
1567 	/*
1568 	 * Optimize for the case when writemappings is not going to
1569 	 * zero.
1570 	 */
1571 	inc = end - start;
1572 	if (object->un_pager.vnp.writemappings != inc) {
1573 		object->un_pager.vnp.writemappings -= inc;
1574 		VM_OBJECT_WUNLOCK(object);
1575 		return;
1576 	}
1577 
1578 	vp = object->handle;
1579 	vhold(vp);
1580 	VM_OBJECT_WUNLOCK(object);
1581 	mp = NULL;
1582 	vn_start_write(vp, &mp, V_WAIT);
1583 	vn_lock(vp, LK_SHARED | LK_RETRY);
1584 
1585 	/*
1586 	 * Decrement the object's writemappings, by swapping the start
1587 	 * and end arguments for vnode_pager_update_writecount().  If
1588 	 * there was not a race with vnode reclaimation, then the
1589 	 * vnode's v_writecount is decremented.
1590 	 */
1591 	vnode_pager_update_writecount(object, end, start);
1592 	VOP_UNLOCK(vp);
1593 	vdrop(vp);
1594 	if (mp != NULL)
1595 		vn_finished_write(mp);
1596 }
1597