xref: /freebsd/sys/vm/vnode_pager.c (revision c23c555bc15ce1523b95fb8da99ae77c0bb0977e)
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 	.pgo_set_writeable_dirty = vm_object_set_writeable_dirty_,
119 	.pgo_mightbedirty = vm_object_mightbedirty_,
120 };
121 
122 static struct domainset *vnode_domainset = NULL;
123 
124 SYSCTL_PROC(_debug, OID_AUTO, vnode_domainset,
125     CTLTYPE_STRING | CTLFLAG_MPSAFE | CTLFLAG_RW, &vnode_domainset, 0,
126     sysctl_handle_domainset, "A", "Default vnode NUMA policy");
127 
128 static int nvnpbufs;
129 SYSCTL_INT(_vm, OID_AUTO, vnode_pbufs, CTLFLAG_RDTUN | CTLFLAG_NOFETCH,
130     &nvnpbufs, 0, "number of physical buffers allocated for vnode pager");
131 
132 static uma_zone_t vnode_pbuf_zone;
133 
134 static void
135 vnode_pager_init(void *dummy)
136 {
137 
138 #ifdef __LP64__
139 	nvnpbufs = nswbuf * 2;
140 #else
141 	nvnpbufs = nswbuf / 2;
142 #endif
143 	TUNABLE_INT_FETCH("vm.vnode_pbufs", &nvnpbufs);
144 	vnode_pbuf_zone = pbuf_zsecond_create("vnpbuf", nvnpbufs);
145 }
146 SYSINIT(vnode_pager, SI_SUB_CPU, SI_ORDER_ANY, vnode_pager_init, NULL);
147 
148 /* Create the VM system backing object for this vnode */
149 int
150 vnode_create_vobject(struct vnode *vp, off_t isize, struct thread *td)
151 {
152 	vm_object_t object;
153 	vm_ooffset_t size = isize;
154 	struct vattr va;
155 	bool last;
156 
157 	if (!vn_isdisk(vp) && vn_canvmio(vp) == FALSE)
158 		return (0);
159 
160 	object = vp->v_object;
161 	if (object != NULL)
162 		return (0);
163 
164 	if (size == 0) {
165 		if (vn_isdisk(vp)) {
166 			size = IDX_TO_OFF(INT_MAX);
167 		} else {
168 			if (VOP_GETATTR(vp, &va, td->td_ucred))
169 				return (0);
170 			size = va.va_size;
171 		}
172 	}
173 
174 	object = vnode_pager_alloc(vp, size, 0, 0, td->td_ucred);
175 	/*
176 	 * Dereference the reference we just created.  This assumes
177 	 * that the object is associated with the vp.  We still have
178 	 * to serialize with vnode_pager_dealloc() for the last
179 	 * potential reference.
180 	 */
181 	VM_OBJECT_RLOCK(object);
182 	last = refcount_release(&object->ref_count);
183 	VM_OBJECT_RUNLOCK(object);
184 	if (last)
185 		vrele(vp);
186 
187 	KASSERT(vp->v_object != NULL, ("vnode_create_vobject: NULL object"));
188 
189 	return (0);
190 }
191 
192 void
193 vnode_destroy_vobject(struct vnode *vp)
194 {
195 	struct vm_object *obj;
196 
197 	obj = vp->v_object;
198 	if (obj == NULL || obj->handle != vp)
199 		return;
200 	ASSERT_VOP_ELOCKED(vp, "vnode_destroy_vobject");
201 	VM_OBJECT_WLOCK(obj);
202 	MPASS(obj->type == OBJT_VNODE);
203 	umtx_shm_object_terminated(obj);
204 	if (obj->ref_count == 0) {
205 		KASSERT((obj->flags & OBJ_DEAD) == 0,
206 		   ("vnode_destroy_vobject: Terminating dead object"));
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 		 * Woe to the process that tries to page now :-).
226 		 */
227 		vm_pager_deallocate(obj);
228 		VM_OBJECT_WUNLOCK(obj);
229 	}
230 	KASSERT(vp->v_object == NULL, ("vp %p obj %p", vp, vp->v_object));
231 }
232 
233 /*
234  * Allocate (or lookup) pager for a vnode.
235  * Handle is a vnode pointer.
236  */
237 vm_object_t
238 vnode_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
239     vm_ooffset_t offset, struct ucred *cred)
240 {
241 	vm_object_t object;
242 	struct vnode *vp;
243 
244 	/*
245 	 * Pageout to vnode, no can do yet.
246 	 */
247 	if (handle == NULL)
248 		return (NULL);
249 
250 	vp = (struct vnode *)handle;
251 	ASSERT_VOP_LOCKED(vp, "vnode_pager_alloc");
252 	VNPASS(vp->v_usecount > 0, vp);
253 retry:
254 	object = vp->v_object;
255 
256 	if (object == NULL) {
257 		/*
258 		 * Add an object of the appropriate size
259 		 */
260 		object = vm_object_allocate(OBJT_VNODE,
261 		    OFF_TO_IDX(round_page(size)));
262 
263 		object->un_pager.vnp.vnp_size = size;
264 		object->un_pager.vnp.writemappings = 0;
265 		object->domain.dr_policy = vnode_domainset;
266 		object->handle = handle;
267 		if ((vp->v_vflag & VV_VMSIZEVNLOCK) != 0) {
268 			VM_OBJECT_WLOCK(object);
269 			vm_object_set_flag(object, OBJ_SIZEVNLOCK);
270 			VM_OBJECT_WUNLOCK(object);
271 		}
272 		VI_LOCK(vp);
273 		if (vp->v_object != NULL) {
274 			/*
275 			 * Object has been created while we were allocating.
276 			 */
277 			VI_UNLOCK(vp);
278 			VM_OBJECT_WLOCK(object);
279 			KASSERT(object->ref_count == 1,
280 			    ("leaked ref %p %d", object, object->ref_count));
281 			object->type = OBJT_DEAD;
282 			refcount_init(&object->ref_count, 0);
283 			VM_OBJECT_WUNLOCK(object);
284 			vm_object_destroy(object);
285 			goto retry;
286 		}
287 		vp->v_object = object;
288 		VI_UNLOCK(vp);
289 		vrefact(vp);
290 	} else {
291 		vm_object_reference(object);
292 #if VM_NRESERVLEVEL > 0
293 		if ((object->flags & OBJ_COLORED) == 0) {
294 			VM_OBJECT_WLOCK(object);
295 			vm_object_color(object, 0);
296 			VM_OBJECT_WUNLOCK(object);
297 		}
298 #endif
299 	}
300 	return (object);
301 }
302 
303 /*
304  *	The object must be locked.
305  */
306 static void
307 vnode_pager_dealloc(vm_object_t object)
308 {
309 	struct vnode *vp;
310 	int refs;
311 
312 	vp = object->handle;
313 	if (vp == NULL)
314 		panic("vnode_pager_dealloc: pager already dealloced");
315 
316 	VM_OBJECT_ASSERT_WLOCKED(object);
317 	vm_object_pip_wait(object, "vnpdea");
318 	refs = object->ref_count;
319 
320 	object->handle = NULL;
321 	object->type = OBJT_DEAD;
322 	ASSERT_VOP_ELOCKED(vp, "vnode_pager_dealloc");
323 	if (object->un_pager.vnp.writemappings > 0) {
324 		object->un_pager.vnp.writemappings = 0;
325 		VOP_ADD_WRITECOUNT_CHECKED(vp, -1);
326 		CTR3(KTR_VFS, "%s: vp %p v_writecount decreased to %d",
327 		    __func__, vp, vp->v_writecount);
328 	}
329 	vp->v_object = NULL;
330 	VI_LOCK(vp);
331 
332 	/*
333 	 * vm_map_entry_set_vnode_text() cannot reach this vnode by
334 	 * following object->handle.  Clear all text references now.
335 	 * This also clears the transient references from
336 	 * kern_execve(), which is fine because dead_vnodeops uses nop
337 	 * for VOP_UNSET_TEXT().
338 	 */
339 	if (vp->v_writecount < 0)
340 		vp->v_writecount = 0;
341 	VI_UNLOCK(vp);
342 	VM_OBJECT_WUNLOCK(object);
343 	if (refs > 0)
344 		vunref(vp);
345 	VM_OBJECT_WLOCK(object);
346 }
347 
348 static boolean_t
349 vnode_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
350     int *after)
351 {
352 	struct vnode *vp = object->handle;
353 	daddr_t bn;
354 	uintptr_t lockstate;
355 	int err;
356 	daddr_t reqblock;
357 	int poff;
358 	int bsize;
359 	int pagesperblock, blocksperpage;
360 
361 	VM_OBJECT_ASSERT_LOCKED(object);
362 	/*
363 	 * If no vp or vp is doomed or marked transparent to VM, we do not
364 	 * have the page.
365 	 */
366 	if (vp == NULL || VN_IS_DOOMED(vp))
367 		return FALSE;
368 	/*
369 	 * If the offset is beyond end of file we do
370 	 * not have the page.
371 	 */
372 	if (IDX_TO_OFF(pindex) >= object->un_pager.vnp.vnp_size)
373 		return FALSE;
374 
375 	bsize = vp->v_mount->mnt_stat.f_iosize;
376 	pagesperblock = bsize / PAGE_SIZE;
377 	blocksperpage = 0;
378 	if (pagesperblock > 0) {
379 		reqblock = pindex / pagesperblock;
380 	} else {
381 		blocksperpage = (PAGE_SIZE / bsize);
382 		reqblock = pindex * blocksperpage;
383 	}
384 	lockstate = VM_OBJECT_DROP(object);
385 	err = VOP_BMAP(vp, reqblock, NULL, &bn, after, before);
386 	VM_OBJECT_PICKUP(object, lockstate);
387 	if (err)
388 		return TRUE;
389 	if (bn == -1)
390 		return FALSE;
391 	if (pagesperblock > 0) {
392 		poff = pindex - (reqblock * pagesperblock);
393 		if (before) {
394 			*before *= pagesperblock;
395 			*before += poff;
396 		}
397 		if (after) {
398 			/*
399 			 * The BMAP vop can report a partial block in the
400 			 * 'after', but must not report blocks after EOF.
401 			 * Assert the latter, and truncate 'after' in case
402 			 * of the former.
403 			 */
404 			KASSERT((reqblock + *after) * pagesperblock <
405 			    roundup2(object->size, pagesperblock),
406 			    ("%s: reqblock %jd after %d size %ju", __func__,
407 			    (intmax_t )reqblock, *after,
408 			    (uintmax_t )object->size));
409 			*after *= pagesperblock;
410 			*after += pagesperblock - (poff + 1);
411 			if (pindex + *after >= object->size)
412 				*after = object->size - 1 - pindex;
413 		}
414 	} else {
415 		if (before) {
416 			*before /= blocksperpage;
417 		}
418 
419 		if (after) {
420 			*after /= blocksperpage;
421 		}
422 	}
423 	return TRUE;
424 }
425 
426 /*
427  * Lets the VM system know about a change in size for a file.
428  * We adjust our own internal size and flush any cached pages in
429  * the associated object that are affected by the size change.
430  *
431  * Note: this routine may be invoked as a result of a pager put
432  * operation (possibly at object termination time), so we must be careful.
433  */
434 void
435 vnode_pager_setsize(struct vnode *vp, vm_ooffset_t nsize)
436 {
437 	vm_object_t object;
438 	vm_page_t m;
439 	vm_pindex_t nobjsize;
440 
441 	if ((object = vp->v_object) == NULL)
442 		return;
443 #ifdef DEBUG_VFS_LOCKS
444 	{
445 		struct mount *mp;
446 
447 		mp = vp->v_mount;
448 		if (mp != NULL && (mp->mnt_kern_flag & MNTK_VMSETSIZE_BUG) == 0)
449 			assert_vop_elocked(vp,
450 			    "vnode_pager_setsize and not locked vnode");
451 	}
452 #endif
453 	VM_OBJECT_WLOCK(object);
454 	if (object->type == OBJT_DEAD) {
455 		VM_OBJECT_WUNLOCK(object);
456 		return;
457 	}
458 	KASSERT(object->type == OBJT_VNODE,
459 	    ("not vnode-backed object %p", object));
460 	if (nsize == object->un_pager.vnp.vnp_size) {
461 		/*
462 		 * Hasn't changed size
463 		 */
464 		VM_OBJECT_WUNLOCK(object);
465 		return;
466 	}
467 	nobjsize = OFF_TO_IDX(nsize + PAGE_MASK);
468 	if (nsize < object->un_pager.vnp.vnp_size) {
469 		/*
470 		 * File has shrunk. Toss any cached pages beyond the new EOF.
471 		 */
472 		if (nobjsize < object->size)
473 			vm_object_page_remove(object, nobjsize, object->size,
474 			    0);
475 		/*
476 		 * this gets rid of garbage at the end of a page that is now
477 		 * only partially backed by the vnode.
478 		 *
479 		 * XXX for some reason (I don't know yet), if we take a
480 		 * completely invalid page and mark it partially valid
481 		 * it can screw up NFS reads, so we don't allow the case.
482 		 */
483 		if (!(nsize & PAGE_MASK))
484 			goto out;
485 		m = vm_page_grab(object, OFF_TO_IDX(nsize), VM_ALLOC_NOCREAT);
486 		if (m == NULL)
487 			goto out;
488 		if (!vm_page_none_valid(m)) {
489 			int base = (int)nsize & PAGE_MASK;
490 			int size = PAGE_SIZE - base;
491 
492 			/*
493 			 * Clear out partial-page garbage in case
494 			 * the page has been mapped.
495 			 */
496 			pmap_zero_page_area(m, base, size);
497 
498 			/*
499 			 * Update the valid bits to reflect the blocks that
500 			 * have been zeroed.  Some of these valid bits may
501 			 * have already been set.
502 			 */
503 			vm_page_set_valid_range(m, base, size);
504 
505 			/*
506 			 * Round "base" to the next block boundary so that the
507 			 * dirty bit for a partially zeroed block is not
508 			 * cleared.
509 			 */
510 			base = roundup2(base, DEV_BSIZE);
511 
512 			/*
513 			 * Clear out partial-page dirty bits.
514 			 *
515 			 * note that we do not clear out the valid
516 			 * bits.  This would prevent bogus_page
517 			 * replacement from working properly.
518 			 */
519 			vm_page_clear_dirty(m, base, PAGE_SIZE - base);
520 		}
521 		vm_page_xunbusy(m);
522 	}
523 out:
524 #if defined(__powerpc__) && !defined(__powerpc64__)
525 	object->un_pager.vnp.vnp_size = nsize;
526 #else
527 	atomic_store_64(&object->un_pager.vnp.vnp_size, nsize);
528 #endif
529 	object->size = nobjsize;
530 	VM_OBJECT_WUNLOCK(object);
531 }
532 
533 /*
534  * calculate the linear (byte) disk address of specified virtual
535  * file address
536  */
537 static int
538 vnode_pager_addr(struct vnode *vp, vm_ooffset_t address, daddr_t *rtaddress,
539     int *run)
540 {
541 	int bsize;
542 	int err;
543 	daddr_t vblock;
544 	daddr_t voffset;
545 
546 	if (VN_IS_DOOMED(vp))
547 		return -1;
548 
549 	bsize = vp->v_mount->mnt_stat.f_iosize;
550 	vblock = address / bsize;
551 	voffset = address % bsize;
552 
553 	err = VOP_BMAP(vp, vblock, NULL, rtaddress, run, NULL);
554 	if (err == 0) {
555 		if (*rtaddress != -1)
556 			*rtaddress += voffset / DEV_BSIZE;
557 		if (run) {
558 			*run += 1;
559 			*run *= bsize / PAGE_SIZE;
560 			*run -= voffset / PAGE_SIZE;
561 		}
562 	}
563 
564 	return (err);
565 }
566 
567 /*
568  * small block filesystem vnode pager input
569  */
570 static int
571 vnode_pager_input_smlfs(vm_object_t object, vm_page_t m)
572 {
573 	struct vnode *vp;
574 	struct bufobj *bo;
575 	struct buf *bp;
576 	struct sf_buf *sf;
577 	daddr_t fileaddr;
578 	vm_offset_t bsize;
579 	vm_page_bits_t bits;
580 	int error, i;
581 
582 	error = 0;
583 	vp = object->handle;
584 	if (VN_IS_DOOMED(vp))
585 		return VM_PAGER_BAD;
586 
587 	bsize = vp->v_mount->mnt_stat.f_iosize;
588 
589 	VOP_BMAP(vp, 0, &bo, 0, NULL, NULL);
590 
591 	sf = sf_buf_alloc(m, 0);
592 
593 	for (i = 0; i < PAGE_SIZE / bsize; i++) {
594 		vm_ooffset_t address;
595 
596 		bits = vm_page_bits(i * bsize, bsize);
597 		if (m->valid & bits)
598 			continue;
599 
600 		address = IDX_TO_OFF(m->pindex) + i * bsize;
601 		if (address >= object->un_pager.vnp.vnp_size) {
602 			fileaddr = -1;
603 		} else {
604 			error = vnode_pager_addr(vp, address, &fileaddr, NULL);
605 			if (error)
606 				break;
607 		}
608 		if (fileaddr != -1) {
609 			bp = uma_zalloc(vnode_pbuf_zone, M_WAITOK);
610 
611 			/* build a minimal buffer header */
612 			bp->b_iocmd = BIO_READ;
613 			bp->b_iodone = bdone;
614 			KASSERT(bp->b_rcred == NOCRED, ("leaking read ucred"));
615 			KASSERT(bp->b_wcred == NOCRED, ("leaking write ucred"));
616 			bp->b_rcred = crhold(curthread->td_ucred);
617 			bp->b_wcred = crhold(curthread->td_ucred);
618 			bp->b_data = (caddr_t)sf_buf_kva(sf) + i * bsize;
619 			bp->b_blkno = fileaddr;
620 			pbgetbo(bo, bp);
621 			bp->b_vp = vp;
622 			bp->b_bcount = bsize;
623 			bp->b_bufsize = bsize;
624 			bp->b_runningbufspace = bp->b_bufsize;
625 			atomic_add_long(&runningbufspace, bp->b_runningbufspace);
626 
627 			/* do the input */
628 			bp->b_iooffset = dbtob(bp->b_blkno);
629 			bstrategy(bp);
630 
631 			bwait(bp, PVM, "vnsrd");
632 
633 			if ((bp->b_ioflags & BIO_ERROR) != 0) {
634 				KASSERT(bp->b_error != 0,
635 				    ("%s: buf error but b_error == 0\n", __func__));
636 				error = bp->b_error;
637 			}
638 
639 			/*
640 			 * free the buffer header back to the swap buffer pool
641 			 */
642 			bp->b_vp = NULL;
643 			pbrelbo(bp);
644 			uma_zfree(vnode_pbuf_zone, bp);
645 			if (error)
646 				break;
647 		} else
648 			bzero((caddr_t)sf_buf_kva(sf) + i * bsize, bsize);
649 		KASSERT((m->dirty & bits) == 0,
650 		    ("vnode_pager_input_smlfs: page %p is dirty", m));
651 		vm_page_bits_set(m, &m->valid, bits);
652 	}
653 	sf_buf_free(sf);
654 	if (error) {
655 		return VM_PAGER_ERROR;
656 	}
657 	return VM_PAGER_OK;
658 }
659 
660 /*
661  * old style vnode pager input routine
662  */
663 static int
664 vnode_pager_input_old(vm_object_t object, vm_page_t m)
665 {
666 	struct uio auio;
667 	struct iovec aiov;
668 	int error;
669 	int size;
670 	struct sf_buf *sf;
671 	struct vnode *vp;
672 
673 	VM_OBJECT_ASSERT_WLOCKED(object);
674 	error = 0;
675 
676 	/*
677 	 * Return failure if beyond current EOF
678 	 */
679 	if (IDX_TO_OFF(m->pindex) >= object->un_pager.vnp.vnp_size) {
680 		return VM_PAGER_BAD;
681 	} else {
682 		size = PAGE_SIZE;
683 		if (IDX_TO_OFF(m->pindex) + size > object->un_pager.vnp.vnp_size)
684 			size = object->un_pager.vnp.vnp_size - IDX_TO_OFF(m->pindex);
685 		vp = object->handle;
686 		VM_OBJECT_WUNLOCK(object);
687 
688 		/*
689 		 * Allocate a kernel virtual address and initialize so that
690 		 * we can use VOP_READ/WRITE routines.
691 		 */
692 		sf = sf_buf_alloc(m, 0);
693 
694 		aiov.iov_base = (caddr_t)sf_buf_kva(sf);
695 		aiov.iov_len = size;
696 		auio.uio_iov = &aiov;
697 		auio.uio_iovcnt = 1;
698 		auio.uio_offset = IDX_TO_OFF(m->pindex);
699 		auio.uio_segflg = UIO_SYSSPACE;
700 		auio.uio_rw = UIO_READ;
701 		auio.uio_resid = size;
702 		auio.uio_td = curthread;
703 
704 		error = VOP_READ(vp, &auio, 0, curthread->td_ucred);
705 		if (!error) {
706 			int count = size - auio.uio_resid;
707 
708 			if (count == 0)
709 				error = EINVAL;
710 			else if (count != PAGE_SIZE)
711 				bzero((caddr_t)sf_buf_kva(sf) + count,
712 				    PAGE_SIZE - count);
713 		}
714 		sf_buf_free(sf);
715 
716 		VM_OBJECT_WLOCK(object);
717 	}
718 	KASSERT(m->dirty == 0, ("vnode_pager_input_old: page %p is dirty", m));
719 	if (!error)
720 		vm_page_valid(m);
721 	return error ? VM_PAGER_ERROR : VM_PAGER_OK;
722 }
723 
724 /*
725  * generic vnode pager input routine
726  */
727 
728 /*
729  * Local media VFS's that do not implement their own VOP_GETPAGES
730  * should have their VOP_GETPAGES call to vnode_pager_generic_getpages()
731  * to implement the previous behaviour.
732  *
733  * All other FS's should use the bypass to get to the local media
734  * backing vp's VOP_GETPAGES.
735  */
736 static int
737 vnode_pager_getpages(vm_object_t object, vm_page_t *m, int count, int *rbehind,
738     int *rahead)
739 {
740 	struct vnode *vp;
741 	int rtval;
742 
743 	/* Handle is stable with paging in progress. */
744 	vp = object->handle;
745 	rtval = VOP_GETPAGES(vp, m, count, rbehind, rahead);
746 	KASSERT(rtval != EOPNOTSUPP,
747 	    ("vnode_pager: FS getpages not implemented\n"));
748 	return rtval;
749 }
750 
751 static int
752 vnode_pager_getpages_async(vm_object_t object, vm_page_t *m, int count,
753     int *rbehind, int *rahead, vop_getpages_iodone_t iodone, void *arg)
754 {
755 	struct vnode *vp;
756 	int rtval;
757 
758 	vp = object->handle;
759 	rtval = VOP_GETPAGES_ASYNC(vp, m, count, rbehind, rahead, iodone, arg);
760 	KASSERT(rtval != EOPNOTSUPP,
761 	    ("vnode_pager: FS getpages_async not implemented\n"));
762 	return (rtval);
763 }
764 
765 /*
766  * The implementation of VOP_GETPAGES() and VOP_GETPAGES_ASYNC() for
767  * local filesystems, where partially valid pages can only occur at
768  * the end of file.
769  */
770 int
771 vnode_pager_local_getpages(struct vop_getpages_args *ap)
772 {
773 
774 	return (vnode_pager_generic_getpages(ap->a_vp, ap->a_m, ap->a_count,
775 	    ap->a_rbehind, ap->a_rahead, NULL, NULL));
776 }
777 
778 int
779 vnode_pager_local_getpages_async(struct vop_getpages_async_args *ap)
780 {
781 	int error;
782 
783 	error = vnode_pager_generic_getpages(ap->a_vp, ap->a_m, ap->a_count,
784 	    ap->a_rbehind, ap->a_rahead, ap->a_iodone, ap->a_arg);
785 	if (error != 0 && ap->a_iodone != NULL)
786 		ap->a_iodone(ap->a_arg, ap->a_m, ap->a_count, error);
787 	return (error);
788 }
789 
790 /*
791  * This is now called from local media FS's to operate against their
792  * own vnodes if they fail to implement VOP_GETPAGES.
793  */
794 int
795 vnode_pager_generic_getpages(struct vnode *vp, vm_page_t *m, int count,
796     int *a_rbehind, int *a_rahead, vop_getpages_iodone_t iodone, void *arg)
797 {
798 	vm_object_t object;
799 	struct bufobj *bo;
800 	struct buf *bp;
801 	off_t foff;
802 #ifdef INVARIANTS
803 	off_t blkno0;
804 #endif
805 	int bsize, pagesperblock;
806 	int error, before, after, rbehind, rahead, poff, i;
807 	int bytecount, secmask;
808 
809 	KASSERT(vp->v_type != VCHR && vp->v_type != VBLK,
810 	    ("%s does not support devices", __func__));
811 
812 	if (VN_IS_DOOMED(vp))
813 		return (VM_PAGER_BAD);
814 
815 	object = vp->v_object;
816 	foff = IDX_TO_OFF(m[0]->pindex);
817 	bsize = vp->v_mount->mnt_stat.f_iosize;
818 	pagesperblock = bsize / PAGE_SIZE;
819 
820 	KASSERT(foff < object->un_pager.vnp.vnp_size,
821 	    ("%s: page %p offset beyond vp %p size", __func__, m[0], vp));
822 	KASSERT(count <= atop(maxphys),
823 	    ("%s: requested %d pages", __func__, count));
824 
825 	/*
826 	 * The last page has valid blocks.  Invalid part can only
827 	 * exist at the end of file, and the page is made fully valid
828 	 * by zeroing in vm_pager_get_pages().
829 	 */
830 	if (!vm_page_none_valid(m[count - 1]) && --count == 0) {
831 		if (iodone != NULL)
832 			iodone(arg, m, 1, 0);
833 		return (VM_PAGER_OK);
834 	}
835 
836 	bp = uma_zalloc(vnode_pbuf_zone, M_WAITOK);
837 	MPASS((bp->b_flags & B_MAXPHYS) != 0);
838 
839 	/*
840 	 * Get the underlying device blocks for the file with VOP_BMAP().
841 	 * If the file system doesn't support VOP_BMAP, use old way of
842 	 * getting pages via VOP_READ.
843 	 */
844 	error = VOP_BMAP(vp, foff / bsize, &bo, &bp->b_blkno, &after, &before);
845 	if (error == EOPNOTSUPP) {
846 		uma_zfree(vnode_pbuf_zone, bp);
847 		VM_OBJECT_WLOCK(object);
848 		for (i = 0; i < count; i++) {
849 			VM_CNT_INC(v_vnodein);
850 			VM_CNT_INC(v_vnodepgsin);
851 			error = vnode_pager_input_old(object, m[i]);
852 			if (error)
853 				break;
854 		}
855 		VM_OBJECT_WUNLOCK(object);
856 		return (error);
857 	} else if (error != 0) {
858 		uma_zfree(vnode_pbuf_zone, bp);
859 		return (VM_PAGER_ERROR);
860 	}
861 
862 	/*
863 	 * If the file system supports BMAP, but blocksize is smaller
864 	 * than a page size, then use special small filesystem code.
865 	 */
866 	if (pagesperblock == 0) {
867 		uma_zfree(vnode_pbuf_zone, bp);
868 		for (i = 0; i < count; i++) {
869 			VM_CNT_INC(v_vnodein);
870 			VM_CNT_INC(v_vnodepgsin);
871 			error = vnode_pager_input_smlfs(object, m[i]);
872 			if (error)
873 				break;
874 		}
875 		return (error);
876 	}
877 
878 	/*
879 	 * A sparse file can be encountered only for a single page request,
880 	 * which may not be preceded by call to vm_pager_haspage().
881 	 */
882 	if (bp->b_blkno == -1) {
883 		KASSERT(count == 1,
884 		    ("%s: array[%d] request to a sparse file %p", __func__,
885 		    count, vp));
886 		uma_zfree(vnode_pbuf_zone, bp);
887 		pmap_zero_page(m[0]);
888 		KASSERT(m[0]->dirty == 0, ("%s: page %p is dirty",
889 		    __func__, m[0]));
890 		vm_page_valid(m[0]);
891 		return (VM_PAGER_OK);
892 	}
893 
894 #ifdef INVARIANTS
895 	blkno0 = bp->b_blkno;
896 #endif
897 	bp->b_blkno += (foff % bsize) / DEV_BSIZE;
898 
899 	/* Recalculate blocks available after/before to pages. */
900 	poff = (foff % bsize) / PAGE_SIZE;
901 	before *= pagesperblock;
902 	before += poff;
903 	after *= pagesperblock;
904 	after += pagesperblock - (poff + 1);
905 	if (m[0]->pindex + after >= object->size)
906 		after = object->size - 1 - m[0]->pindex;
907 	KASSERT(count <= after + 1, ("%s: %d pages asked, can do only %d",
908 	    __func__, count, after + 1));
909 	after -= count - 1;
910 
911 	/* Trim requested rbehind/rahead to possible values. */
912 	rbehind = a_rbehind ? *a_rbehind : 0;
913 	rahead = a_rahead ? *a_rahead : 0;
914 	rbehind = min(rbehind, before);
915 	rbehind = min(rbehind, m[0]->pindex);
916 	rahead = min(rahead, after);
917 	rahead = min(rahead, object->size - m[count - 1]->pindex);
918 	/*
919 	 * Check that total amount of pages fit into buf.  Trim rbehind and
920 	 * rahead evenly if not.
921 	 */
922 	if (rbehind + rahead + count > atop(maxphys)) {
923 		int trim, sum;
924 
925 		trim = rbehind + rahead + count - atop(maxphys) + 1;
926 		sum = rbehind + rahead;
927 		if (rbehind == before) {
928 			/* Roundup rbehind trim to block size. */
929 			rbehind -= roundup(trim * rbehind / sum, pagesperblock);
930 			if (rbehind < 0)
931 				rbehind = 0;
932 		} else
933 			rbehind -= trim * rbehind / sum;
934 		rahead -= trim * rahead / sum;
935 	}
936 	KASSERT(rbehind + rahead + count <= atop(maxphys),
937 	    ("%s: behind %d ahead %d count %d maxphys %lu", __func__,
938 	    rbehind, rahead, count, maxphys));
939 
940 	/*
941 	 * Fill in the bp->b_pages[] array with requested and optional
942 	 * read behind or read ahead pages.  Read behind pages are looked
943 	 * up in a backward direction, down to a first cached page.  Same
944 	 * for read ahead pages, but there is no need to shift the array
945 	 * in case of encountering a cached page.
946 	 */
947 	i = bp->b_npages = 0;
948 	if (rbehind) {
949 		vm_pindex_t startpindex, tpindex;
950 		vm_page_t p;
951 
952 		VM_OBJECT_WLOCK(object);
953 		startpindex = m[0]->pindex - rbehind;
954 		if ((p = TAILQ_PREV(m[0], pglist, listq)) != NULL &&
955 		    p->pindex >= startpindex)
956 			startpindex = p->pindex + 1;
957 
958 		/* tpindex is unsigned; beware of numeric underflow. */
959 		for (tpindex = m[0]->pindex - 1;
960 		    tpindex >= startpindex && tpindex < m[0]->pindex;
961 		    tpindex--, i++) {
962 			p = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL);
963 			if (p == NULL) {
964 				/* Shift the array. */
965 				for (int j = 0; j < i; j++)
966 					bp->b_pages[j] = bp->b_pages[j +
967 					    tpindex + 1 - startpindex];
968 				break;
969 			}
970 			bp->b_pages[tpindex - startpindex] = p;
971 		}
972 
973 		bp->b_pgbefore = i;
974 		bp->b_npages += i;
975 		bp->b_blkno -= IDX_TO_OFF(i) / DEV_BSIZE;
976 	} else
977 		bp->b_pgbefore = 0;
978 
979 	/* Requested pages. */
980 	for (int j = 0; j < count; j++, i++)
981 		bp->b_pages[i] = m[j];
982 	bp->b_npages += count;
983 
984 	if (rahead) {
985 		vm_pindex_t endpindex, tpindex;
986 		vm_page_t p;
987 
988 		if (!VM_OBJECT_WOWNED(object))
989 			VM_OBJECT_WLOCK(object);
990 		endpindex = m[count - 1]->pindex + rahead + 1;
991 		if ((p = TAILQ_NEXT(m[count - 1], listq)) != NULL &&
992 		    p->pindex < endpindex)
993 			endpindex = p->pindex;
994 		if (endpindex > object->size)
995 			endpindex = object->size;
996 
997 		for (tpindex = m[count - 1]->pindex + 1;
998 		    tpindex < endpindex; i++, tpindex++) {
999 			p = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL);
1000 			if (p == NULL)
1001 				break;
1002 			bp->b_pages[i] = p;
1003 		}
1004 
1005 		bp->b_pgafter = i - bp->b_npages;
1006 		bp->b_npages = i;
1007 	} else
1008 		bp->b_pgafter = 0;
1009 
1010 	if (VM_OBJECT_WOWNED(object))
1011 		VM_OBJECT_WUNLOCK(object);
1012 
1013 	/* Report back actual behind/ahead read. */
1014 	if (a_rbehind)
1015 		*a_rbehind = bp->b_pgbefore;
1016 	if (a_rahead)
1017 		*a_rahead = bp->b_pgafter;
1018 
1019 #ifdef INVARIANTS
1020 	KASSERT(bp->b_npages <= atop(maxphys),
1021 	    ("%s: buf %p overflowed", __func__, bp));
1022 	for (int j = 1, prev = 0; j < bp->b_npages; j++) {
1023 		if (bp->b_pages[j] == bogus_page)
1024 			continue;
1025 		KASSERT(bp->b_pages[j]->pindex - bp->b_pages[prev]->pindex ==
1026 		    j - prev, ("%s: pages array not consecutive, bp %p",
1027 		     __func__, bp));
1028 		prev = j;
1029 	}
1030 #endif
1031 
1032 	/*
1033 	 * Recalculate first offset and bytecount with regards to read behind.
1034 	 * Truncate bytecount to vnode real size and round up physical size
1035 	 * for real devices.
1036 	 */
1037 	foff = IDX_TO_OFF(bp->b_pages[0]->pindex);
1038 	bytecount = bp->b_npages << PAGE_SHIFT;
1039 	if ((foff + bytecount) > object->un_pager.vnp.vnp_size)
1040 		bytecount = object->un_pager.vnp.vnp_size - foff;
1041 	secmask = bo->bo_bsize - 1;
1042 	KASSERT(secmask < PAGE_SIZE && secmask > 0,
1043 	    ("%s: sector size %d too large", __func__, secmask + 1));
1044 	bytecount = (bytecount + secmask) & ~secmask;
1045 
1046 	/*
1047 	 * And map the pages to be read into the kva, if the filesystem
1048 	 * requires mapped buffers.
1049 	 */
1050 	if ((vp->v_mount->mnt_kern_flag & MNTK_UNMAPPED_BUFS) != 0 &&
1051 	    unmapped_buf_allowed) {
1052 		bp->b_data = unmapped_buf;
1053 		bp->b_offset = 0;
1054 	} else {
1055 		bp->b_data = bp->b_kvabase;
1056 		pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages);
1057 	}
1058 
1059 	/* Build a minimal buffer header. */
1060 	bp->b_iocmd = BIO_READ;
1061 	KASSERT(bp->b_rcred == NOCRED, ("leaking read ucred"));
1062 	KASSERT(bp->b_wcred == NOCRED, ("leaking write ucred"));
1063 	bp->b_rcred = crhold(curthread->td_ucred);
1064 	bp->b_wcred = crhold(curthread->td_ucred);
1065 	pbgetbo(bo, bp);
1066 	bp->b_vp = vp;
1067 	bp->b_bcount = bp->b_bufsize = bp->b_runningbufspace = bytecount;
1068 	bp->b_iooffset = dbtob(bp->b_blkno);
1069 	KASSERT(IDX_TO_OFF(m[0]->pindex - bp->b_pages[0]->pindex) ==
1070 	    (blkno0 - bp->b_blkno) * DEV_BSIZE +
1071 	    IDX_TO_OFF(m[0]->pindex) % bsize,
1072 	    ("wrong offsets bsize %d m[0] %ju b_pages[0] %ju "
1073 	    "blkno0 %ju b_blkno %ju", bsize,
1074 	    (uintmax_t)m[0]->pindex, (uintmax_t)bp->b_pages[0]->pindex,
1075 	    (uintmax_t)blkno0, (uintmax_t)bp->b_blkno));
1076 
1077 	atomic_add_long(&runningbufspace, bp->b_runningbufspace);
1078 	VM_CNT_INC(v_vnodein);
1079 	VM_CNT_ADD(v_vnodepgsin, bp->b_npages);
1080 
1081 	if (iodone != NULL) { /* async */
1082 		bp->b_pgiodone = iodone;
1083 		bp->b_caller1 = arg;
1084 		bp->b_iodone = vnode_pager_generic_getpages_done_async;
1085 		bp->b_flags |= B_ASYNC;
1086 		BUF_KERNPROC(bp);
1087 		bstrategy(bp);
1088 		return (VM_PAGER_OK);
1089 	} else {
1090 		bp->b_iodone = bdone;
1091 		bstrategy(bp);
1092 		bwait(bp, PVM, "vnread");
1093 		error = vnode_pager_generic_getpages_done(bp);
1094 		for (i = 0; i < bp->b_npages; i++)
1095 			bp->b_pages[i] = NULL;
1096 		bp->b_vp = NULL;
1097 		pbrelbo(bp);
1098 		uma_zfree(vnode_pbuf_zone, bp);
1099 		return (error != 0 ? VM_PAGER_ERROR : VM_PAGER_OK);
1100 	}
1101 }
1102 
1103 static void
1104 vnode_pager_generic_getpages_done_async(struct buf *bp)
1105 {
1106 	int error;
1107 
1108 	error = vnode_pager_generic_getpages_done(bp);
1109 	/* Run the iodone upon the requested range. */
1110 	bp->b_pgiodone(bp->b_caller1, bp->b_pages + bp->b_pgbefore,
1111 	    bp->b_npages - bp->b_pgbefore - bp->b_pgafter, error);
1112 	for (int i = 0; i < bp->b_npages; i++)
1113 		bp->b_pages[i] = NULL;
1114 	bp->b_vp = NULL;
1115 	pbrelbo(bp);
1116 	uma_zfree(vnode_pbuf_zone, bp);
1117 }
1118 
1119 static int
1120 vnode_pager_generic_getpages_done(struct buf *bp)
1121 {
1122 	vm_object_t object;
1123 	off_t tfoff, nextoff;
1124 	int i, error;
1125 
1126 	KASSERT((bp->b_ioflags & BIO_ERROR) == 0 || bp->b_error != 0,
1127 	    ("%s: buf error but b_error == 0\n", __func__));
1128 	error = (bp->b_ioflags & BIO_ERROR) != 0 ? bp->b_error : 0;
1129 	object = bp->b_vp->v_object;
1130 
1131 	if (error == 0 && bp->b_bcount != bp->b_npages * PAGE_SIZE) {
1132 		if (!buf_mapped(bp)) {
1133 			bp->b_data = bp->b_kvabase;
1134 			pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages,
1135 			    bp->b_npages);
1136 		}
1137 		bzero(bp->b_data + bp->b_bcount,
1138 		    PAGE_SIZE * bp->b_npages - bp->b_bcount);
1139 	}
1140 	if (buf_mapped(bp)) {
1141 		pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages);
1142 		bp->b_data = unmapped_buf;
1143 	}
1144 
1145 	/*
1146 	 * If the read failed, we must free any read ahead/behind pages here.
1147 	 * The requested pages are freed by the caller (for sync requests)
1148 	 * or by the bp->b_pgiodone callback (for async requests).
1149 	 */
1150 	if (error != 0) {
1151 		VM_OBJECT_WLOCK(object);
1152 		for (i = 0; i < bp->b_pgbefore; i++)
1153 			vm_page_free_invalid(bp->b_pages[i]);
1154 		for (i = bp->b_npages - bp->b_pgafter; i < bp->b_npages; i++)
1155 			vm_page_free_invalid(bp->b_pages[i]);
1156 		VM_OBJECT_WUNLOCK(object);
1157 		return (error);
1158 	}
1159 
1160 	/* Read lock to protect size. */
1161 	VM_OBJECT_RLOCK(object);
1162 	for (i = 0, tfoff = IDX_TO_OFF(bp->b_pages[0]->pindex);
1163 	    i < bp->b_npages; i++, tfoff = nextoff) {
1164 		vm_page_t mt;
1165 
1166 		nextoff = tfoff + PAGE_SIZE;
1167 		mt = bp->b_pages[i];
1168 		if (mt == bogus_page)
1169 			continue;
1170 
1171 		if (nextoff <= object->un_pager.vnp.vnp_size) {
1172 			/*
1173 			 * Read filled up entire page.
1174 			 */
1175 			vm_page_valid(mt);
1176 			KASSERT(mt->dirty == 0,
1177 			    ("%s: page %p is dirty", __func__, mt));
1178 			KASSERT(!pmap_page_is_mapped(mt),
1179 			    ("%s: page %p is mapped", __func__, mt));
1180 		} else {
1181 			/*
1182 			 * Read did not fill up entire page.
1183 			 *
1184 			 * Currently we do not set the entire page valid,
1185 			 * we just try to clear the piece that we couldn't
1186 			 * read.
1187 			 */
1188 			vm_page_set_valid_range(mt, 0,
1189 			    object->un_pager.vnp.vnp_size - tfoff);
1190 			KASSERT((mt->dirty & vm_page_bits(0,
1191 			    object->un_pager.vnp.vnp_size - tfoff)) == 0,
1192 			    ("%s: page %p is dirty", __func__, mt));
1193 		}
1194 
1195 		if (i < bp->b_pgbefore || i >= bp->b_npages - bp->b_pgafter)
1196 			vm_page_readahead_finish(mt);
1197 	}
1198 	VM_OBJECT_RUNLOCK(object);
1199 
1200 	return (error);
1201 }
1202 
1203 /*
1204  * EOPNOTSUPP is no longer legal.  For local media VFS's that do not
1205  * implement their own VOP_PUTPAGES, their VOP_PUTPAGES should call to
1206  * vnode_pager_generic_putpages() to implement the previous behaviour.
1207  *
1208  * All other FS's should use the bypass to get to the local media
1209  * backing vp's VOP_PUTPAGES.
1210  */
1211 static void
1212 vnode_pager_putpages(vm_object_t object, vm_page_t *m, int count,
1213     int flags, int *rtvals)
1214 {
1215 	int rtval;
1216 	struct vnode *vp;
1217 	int bytes = count * PAGE_SIZE;
1218 
1219 	/*
1220 	 * Force synchronous operation if we are extremely low on memory
1221 	 * to prevent a low-memory deadlock.  VOP operations often need to
1222 	 * allocate more memory to initiate the I/O ( i.e. do a BMAP
1223 	 * operation ).  The swapper handles the case by limiting the amount
1224 	 * of asynchronous I/O, but that sort of solution doesn't scale well
1225 	 * for the vnode pager without a lot of work.
1226 	 *
1227 	 * Also, the backing vnode's iodone routine may not wake the pageout
1228 	 * daemon up.  This should be probably be addressed XXX.
1229 	 */
1230 
1231 	if (vm_page_count_min())
1232 		flags |= VM_PAGER_PUT_SYNC;
1233 
1234 	/*
1235 	 * Call device-specific putpages function
1236 	 */
1237 	vp = object->handle;
1238 	VM_OBJECT_WUNLOCK(object);
1239 	rtval = VOP_PUTPAGES(vp, m, bytes, flags, rtvals);
1240 	KASSERT(rtval != EOPNOTSUPP,
1241 	    ("vnode_pager: stale FS putpages\n"));
1242 	VM_OBJECT_WLOCK(object);
1243 }
1244 
1245 static int
1246 vn_off2bidx(vm_ooffset_t offset)
1247 {
1248 
1249 	return ((offset & PAGE_MASK) / DEV_BSIZE);
1250 }
1251 
1252 static bool
1253 vn_dirty_blk(vm_page_t m, vm_ooffset_t offset)
1254 {
1255 
1256 	KASSERT(IDX_TO_OFF(m->pindex) <= offset &&
1257 	    offset < IDX_TO_OFF(m->pindex + 1),
1258 	    ("page %p pidx %ju offset %ju", m, (uintmax_t)m->pindex,
1259 	    (uintmax_t)offset));
1260 	return ((m->dirty & ((vm_page_bits_t)1 << vn_off2bidx(offset))) != 0);
1261 }
1262 
1263 /*
1264  * This is now called from local media FS's to operate against their
1265  * own vnodes if they fail to implement VOP_PUTPAGES.
1266  *
1267  * This is typically called indirectly via the pageout daemon and
1268  * clustering has already typically occurred, so in general we ask the
1269  * underlying filesystem to write the data out asynchronously rather
1270  * then delayed.
1271  */
1272 int
1273 vnode_pager_generic_putpages(struct vnode *vp, vm_page_t *ma, int bytecount,
1274     int flags, int *rtvals)
1275 {
1276 	vm_object_t object;
1277 	vm_page_t m;
1278 	vm_ooffset_t maxblksz, next_offset, poffset, prev_offset;
1279 	struct uio auio;
1280 	struct iovec aiov;
1281 	off_t prev_resid, wrsz;
1282 	int count, error, i, maxsize, ncount, pgoff, ppscheck;
1283 	bool in_hole;
1284 	static struct timeval lastfail;
1285 	static int curfail;
1286 
1287 	object = vp->v_object;
1288 	count = bytecount / PAGE_SIZE;
1289 
1290 	for (i = 0; i < count; i++)
1291 		rtvals[i] = VM_PAGER_ERROR;
1292 
1293 	if ((int64_t)ma[0]->pindex < 0) {
1294 		printf("vnode_pager_generic_putpages: "
1295 		    "attempt to write meta-data 0x%jx(%lx)\n",
1296 		    (uintmax_t)ma[0]->pindex, (u_long)ma[0]->dirty);
1297 		rtvals[0] = VM_PAGER_BAD;
1298 		return (VM_PAGER_BAD);
1299 	}
1300 
1301 	maxsize = count * PAGE_SIZE;
1302 	ncount = count;
1303 
1304 	poffset = IDX_TO_OFF(ma[0]->pindex);
1305 
1306 	/*
1307 	 * If the page-aligned write is larger then the actual file we
1308 	 * have to invalidate pages occurring beyond the file EOF.  However,
1309 	 * there is an edge case where a file may not be page-aligned where
1310 	 * the last page is partially invalid.  In this case the filesystem
1311 	 * may not properly clear the dirty bits for the entire page (which
1312 	 * could be VM_PAGE_BITS_ALL due to the page having been mmap()d).
1313 	 * With the page busied we are free to fix up the dirty bits here.
1314 	 *
1315 	 * We do not under any circumstances truncate the valid bits, as
1316 	 * this will screw up bogus page replacement.
1317 	 */
1318 	VM_OBJECT_RLOCK(object);
1319 	if (maxsize + poffset > object->un_pager.vnp.vnp_size) {
1320 		if (object->un_pager.vnp.vnp_size > poffset) {
1321 			maxsize = object->un_pager.vnp.vnp_size - poffset;
1322 			ncount = btoc(maxsize);
1323 			if ((pgoff = (int)maxsize & PAGE_MASK) != 0) {
1324 				pgoff = roundup2(pgoff, DEV_BSIZE);
1325 
1326 				/*
1327 				 * If the page is busy and the following
1328 				 * conditions hold, then the page's dirty
1329 				 * field cannot be concurrently changed by a
1330 				 * pmap operation.
1331 				 */
1332 				m = ma[ncount - 1];
1333 				vm_page_assert_sbusied(m);
1334 				KASSERT(!pmap_page_is_write_mapped(m),
1335 		("vnode_pager_generic_putpages: page %p is not read-only", m));
1336 				MPASS(m->dirty != 0);
1337 				vm_page_clear_dirty(m, pgoff, PAGE_SIZE -
1338 				    pgoff);
1339 			}
1340 		} else {
1341 			maxsize = 0;
1342 			ncount = 0;
1343 		}
1344 		for (i = ncount; i < count; i++)
1345 			rtvals[i] = VM_PAGER_BAD;
1346 	}
1347 	VM_OBJECT_RUNLOCK(object);
1348 
1349 	auio.uio_iov = &aiov;
1350 	auio.uio_segflg = UIO_NOCOPY;
1351 	auio.uio_rw = UIO_WRITE;
1352 	auio.uio_td = NULL;
1353 	maxblksz = roundup2(poffset + maxsize, DEV_BSIZE);
1354 
1355 	for (prev_offset = poffset; prev_offset < maxblksz;) {
1356 		/* Skip clean blocks. */
1357 		for (in_hole = true; in_hole && prev_offset < maxblksz;) {
1358 			m = ma[OFF_TO_IDX(prev_offset - poffset)];
1359 			for (i = vn_off2bidx(prev_offset);
1360 			    i < sizeof(vm_page_bits_t) * NBBY &&
1361 			    prev_offset < maxblksz; i++) {
1362 				if (vn_dirty_blk(m, prev_offset)) {
1363 					in_hole = false;
1364 					break;
1365 				}
1366 				prev_offset += DEV_BSIZE;
1367 			}
1368 		}
1369 		if (in_hole)
1370 			goto write_done;
1371 
1372 		/* Find longest run of dirty blocks. */
1373 		for (next_offset = prev_offset; next_offset < maxblksz;) {
1374 			m = ma[OFF_TO_IDX(next_offset - poffset)];
1375 			for (i = vn_off2bidx(next_offset);
1376 			    i < sizeof(vm_page_bits_t) * NBBY &&
1377 			    next_offset < maxblksz; i++) {
1378 				if (!vn_dirty_blk(m, next_offset))
1379 					goto start_write;
1380 				next_offset += DEV_BSIZE;
1381 			}
1382 		}
1383 start_write:
1384 		if (next_offset > poffset + maxsize)
1385 			next_offset = poffset + maxsize;
1386 
1387 		/*
1388 		 * Getting here requires finding a dirty block in the
1389 		 * 'skip clean blocks' loop.
1390 		 */
1391 		MPASS(prev_offset < next_offset);
1392 
1393 		aiov.iov_base = NULL;
1394 		auio.uio_iovcnt = 1;
1395 		auio.uio_offset = prev_offset;
1396 		prev_resid = auio.uio_resid = aiov.iov_len = next_offset -
1397 		    prev_offset;
1398 		error = VOP_WRITE(vp, &auio,
1399 		    vnode_pager_putpages_ioflags(flags), curthread->td_ucred);
1400 
1401 		wrsz = prev_resid - auio.uio_resid;
1402 		if (wrsz == 0) {
1403 			if (ppsratecheck(&lastfail, &curfail, 1) != 0) {
1404 				vn_printf(vp, "vnode_pager_putpages: "
1405 				    "zero-length write at %ju resid %zd\n",
1406 				    auio.uio_offset, auio.uio_resid);
1407 			}
1408 			break;
1409 		}
1410 
1411 		/* Adjust the starting offset for next iteration. */
1412 		prev_offset += wrsz;
1413 		MPASS(auio.uio_offset == prev_offset);
1414 
1415 		ppscheck = 0;
1416 		if (error != 0 && (ppscheck = ppsratecheck(&lastfail,
1417 		    &curfail, 1)) != 0)
1418 			vn_printf(vp, "vnode_pager_putpages: I/O error %d\n",
1419 			    error);
1420 		if (auio.uio_resid != 0 && (ppscheck != 0 ||
1421 		    ppsratecheck(&lastfail, &curfail, 1) != 0))
1422 			vn_printf(vp, "vnode_pager_putpages: residual I/O %zd "
1423 			    "at %ju\n", auio.uio_resid,
1424 			    (uintmax_t)ma[0]->pindex);
1425 		if (error != 0 || auio.uio_resid != 0)
1426 			break;
1427 	}
1428 write_done:
1429 	/* Mark completely processed pages. */
1430 	for (i = 0; i < OFF_TO_IDX(prev_offset - poffset); i++)
1431 		rtvals[i] = VM_PAGER_OK;
1432 	/* Mark partial EOF page. */
1433 	if (prev_offset == poffset + maxsize && (prev_offset & PAGE_MASK) != 0)
1434 		rtvals[i++] = VM_PAGER_OK;
1435 	/* Unwritten pages in range, free bonus if the page is clean. */
1436 	for (; i < ncount; i++)
1437 		rtvals[i] = ma[i]->dirty == 0 ? VM_PAGER_OK : VM_PAGER_ERROR;
1438 	VM_CNT_ADD(v_vnodepgsout, i);
1439 	VM_CNT_INC(v_vnodeout);
1440 	return (rtvals[0]);
1441 }
1442 
1443 int
1444 vnode_pager_putpages_ioflags(int pager_flags)
1445 {
1446 	int ioflags;
1447 
1448 	/*
1449 	 * Pageouts are already clustered, use IO_ASYNC to force a
1450 	 * bawrite() rather then a bdwrite() to prevent paging I/O
1451 	 * from saturating the buffer cache.  Dummy-up the sequential
1452 	 * heuristic to cause large ranges to cluster.  If neither
1453 	 * IO_SYNC or IO_ASYNC is set, the system decides how to
1454 	 * cluster.
1455 	 */
1456 	ioflags = IO_VMIO;
1457 	if ((pager_flags & (VM_PAGER_PUT_SYNC | VM_PAGER_PUT_INVAL)) != 0)
1458 		ioflags |= IO_SYNC;
1459 	else if ((pager_flags & VM_PAGER_CLUSTER_OK) == 0)
1460 		ioflags |= IO_ASYNC;
1461 	ioflags |= (pager_flags & VM_PAGER_PUT_INVAL) != 0 ? IO_INVAL: 0;
1462 	ioflags |= (pager_flags & VM_PAGER_PUT_NOREUSE) != 0 ? IO_NOREUSE : 0;
1463 	ioflags |= IO_SEQMAX << IO_SEQSHIFT;
1464 	return (ioflags);
1465 }
1466 
1467 /*
1468  * vnode_pager_undirty_pages().
1469  *
1470  * A helper to mark pages as clean after pageout that was possibly
1471  * done with a short write.  The lpos argument specifies the page run
1472  * length in bytes, and the written argument specifies how many bytes
1473  * were actually written.  eof is the offset past the last valid byte
1474  * in the vnode using the absolute file position of the first byte in
1475  * the run as the base from which it is computed.
1476  */
1477 void
1478 vnode_pager_undirty_pages(vm_page_t *ma, int *rtvals, int written, off_t eof,
1479     int lpos)
1480 {
1481 	int i, pos, pos_devb;
1482 
1483 	if (written == 0 && eof >= lpos)
1484 		return;
1485 	for (i = 0, pos = 0; pos < written; i++, pos += PAGE_SIZE) {
1486 		if (pos < trunc_page(written)) {
1487 			rtvals[i] = VM_PAGER_OK;
1488 			vm_page_undirty(ma[i]);
1489 		} else {
1490 			/* Partially written page. */
1491 			rtvals[i] = VM_PAGER_AGAIN;
1492 			vm_page_clear_dirty(ma[i], 0, written & PAGE_MASK);
1493 		}
1494 	}
1495 	if (eof >= lpos) /* avoid truncation */
1496 		return;
1497 	for (pos = eof, i = OFF_TO_IDX(trunc_page(pos)); pos < lpos; i++) {
1498 		if (pos != trunc_page(pos)) {
1499 			/*
1500 			 * The page contains the last valid byte in
1501 			 * the vnode, mark the rest of the page as
1502 			 * clean, potentially making the whole page
1503 			 * clean.
1504 			 */
1505 			pos_devb = roundup2(pos & PAGE_MASK, DEV_BSIZE);
1506 			vm_page_clear_dirty(ma[i], pos_devb, PAGE_SIZE -
1507 			    pos_devb);
1508 
1509 			/*
1510 			 * If the page was cleaned, report the pageout
1511 			 * on it as successful.  msync() no longer
1512 			 * needs to write out the page, endlessly
1513 			 * creating write requests and dirty buffers.
1514 			 */
1515 			if (ma[i]->dirty == 0)
1516 				rtvals[i] = VM_PAGER_OK;
1517 
1518 			pos = round_page(pos);
1519 		} else {
1520 			/* vm_pageout_flush() clears dirty */
1521 			rtvals[i] = VM_PAGER_BAD;
1522 			pos += PAGE_SIZE;
1523 		}
1524 	}
1525 }
1526 
1527 static void
1528 vnode_pager_update_writecount(vm_object_t object, vm_offset_t start,
1529     vm_offset_t end)
1530 {
1531 	struct vnode *vp;
1532 	vm_ooffset_t old_wm;
1533 
1534 	VM_OBJECT_WLOCK(object);
1535 	if (object->type != OBJT_VNODE) {
1536 		VM_OBJECT_WUNLOCK(object);
1537 		return;
1538 	}
1539 	old_wm = object->un_pager.vnp.writemappings;
1540 	object->un_pager.vnp.writemappings += (vm_ooffset_t)end - start;
1541 	vp = object->handle;
1542 	if (old_wm == 0 && object->un_pager.vnp.writemappings != 0) {
1543 		ASSERT_VOP_LOCKED(vp, "v_writecount inc");
1544 		VOP_ADD_WRITECOUNT_CHECKED(vp, 1);
1545 		CTR3(KTR_VFS, "%s: vp %p v_writecount increased to %d",
1546 		    __func__, vp, vp->v_writecount);
1547 	} else if (old_wm != 0 && object->un_pager.vnp.writemappings == 0) {
1548 		ASSERT_VOP_LOCKED(vp, "v_writecount dec");
1549 		VOP_ADD_WRITECOUNT_CHECKED(vp, -1);
1550 		CTR3(KTR_VFS, "%s: vp %p v_writecount decreased to %d",
1551 		    __func__, vp, vp->v_writecount);
1552 	}
1553 	VM_OBJECT_WUNLOCK(object);
1554 }
1555 
1556 static void
1557 vnode_pager_release_writecount(vm_object_t object, vm_offset_t start,
1558     vm_offset_t end)
1559 {
1560 	struct vnode *vp;
1561 	struct mount *mp;
1562 	vm_offset_t inc;
1563 
1564 	VM_OBJECT_WLOCK(object);
1565 
1566 	/*
1567 	 * First, recheck the object type to account for the race when
1568 	 * the vnode is reclaimed.
1569 	 */
1570 	if (object->type != OBJT_VNODE) {
1571 		VM_OBJECT_WUNLOCK(object);
1572 		return;
1573 	}
1574 
1575 	/*
1576 	 * Optimize for the case when writemappings is not going to
1577 	 * zero.
1578 	 */
1579 	inc = end - start;
1580 	if (object->un_pager.vnp.writemappings != inc) {
1581 		object->un_pager.vnp.writemappings -= inc;
1582 		VM_OBJECT_WUNLOCK(object);
1583 		return;
1584 	}
1585 
1586 	vp = object->handle;
1587 	vhold(vp);
1588 	VM_OBJECT_WUNLOCK(object);
1589 	mp = NULL;
1590 	vn_start_write(vp, &mp, V_WAIT);
1591 	vn_lock(vp, LK_SHARED | LK_RETRY);
1592 
1593 	/*
1594 	 * Decrement the object's writemappings, by swapping the start
1595 	 * and end arguments for vnode_pager_update_writecount().  If
1596 	 * there was not a race with vnode reclaimation, then the
1597 	 * vnode's v_writecount is decremented.
1598 	 */
1599 	vnode_pager_update_writecount(object, end, start);
1600 	VOP_UNLOCK(vp);
1601 	vdrop(vp);
1602 	if (mp != NULL)
1603 		vn_finished_write(mp);
1604 }
1605