FreeBSD/Linux Kernel Cross Reference
sys/vm/vnode_pager.c
1 /*-
2 * Copyright (c) 1990 University of Utah.
3 * Copyright (c) 1991 The Regents of the University of California.
4 * All rights reserved.
5 * Copyright (c) 1993, 1994 John S. Dyson
6 * Copyright (c) 1995, David Greenman
7 *
8 * This code is derived from software contributed to Berkeley by
9 * the Systems Programming Group of the University of Utah Computer
10 * Science Department.
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
20 * 3. All advertising materials mentioning features or use of this software
21 * must display the following acknowledgement:
22 * This product includes software developed by the University of
23 * California, Berkeley and its contributors.
24 * 4. Neither the name of the University nor the names of its contributors
25 * may be used to endorse or promote products derived from this software
26 * without specific prior written permission.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
31 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
38 * SUCH DAMAGE.
39 *
40 * from: @(#)vnode_pager.c 7.5 (Berkeley) 4/20/91
41 */
42
43 /*
44 * Page to/from files (vnodes).
45 */
46
47 /*
48 * TODO:
49 * Implement VOP_GETPAGES/PUTPAGES interface for filesystems. Will
50 * greatly re-simplify the vnode_pager.
51 */
52
53 #include <sys/cdefs.h>
54 __FBSDID("$FreeBSD: releng/11.0/sys/vm/vnode_pager.c 302343 2016-07-05 11:21:02Z kib $");
55
56 #include "opt_vm.h"
57
58 #include <sys/param.h>
59 #include <sys/systm.h>
60 #include <sys/proc.h>
61 #include <sys/vnode.h>
62 #include <sys/mount.h>
63 #include <sys/bio.h>
64 #include <sys/buf.h>
65 #include <sys/vmmeter.h>
66 #include <sys/limits.h>
67 #include <sys/conf.h>
68 #include <sys/rwlock.h>
69 #include <sys/sf_buf.h>
70
71 #include <machine/atomic.h>
72
73 #include <vm/vm.h>
74 #include <vm/vm_param.h>
75 #include <vm/vm_object.h>
76 #include <vm/vm_page.h>
77 #include <vm/vm_pager.h>
78 #include <vm/vm_map.h>
79 #include <vm/vnode_pager.h>
80 #include <vm/vm_extern.h>
81
82 static int vnode_pager_addr(struct vnode *vp, vm_ooffset_t address,
83 daddr_t *rtaddress, int *run);
84 static int vnode_pager_input_smlfs(vm_object_t object, vm_page_t m);
85 static int vnode_pager_input_old(vm_object_t object, vm_page_t m);
86 static void vnode_pager_dealloc(vm_object_t);
87 static int vnode_pager_getpages(vm_object_t, vm_page_t *, int, int *, int *);
88 static int vnode_pager_getpages_async(vm_object_t, vm_page_t *, int, int *,
89 int *, vop_getpages_iodone_t, void *);
90 static void vnode_pager_putpages(vm_object_t, vm_page_t *, int, int, int *);
91 static boolean_t vnode_pager_haspage(vm_object_t, vm_pindex_t, int *, int *);
92 static vm_object_t vnode_pager_alloc(void *, vm_ooffset_t, vm_prot_t,
93 vm_ooffset_t, struct ucred *cred);
94 static int vnode_pager_generic_getpages_done(struct buf *);
95 static void vnode_pager_generic_getpages_done_async(struct buf *);
96
97 struct pagerops vnodepagerops = {
98 .pgo_alloc = vnode_pager_alloc,
99 .pgo_dealloc = vnode_pager_dealloc,
100 .pgo_getpages = vnode_pager_getpages,
101 .pgo_getpages_async = vnode_pager_getpages_async,
102 .pgo_putpages = vnode_pager_putpages,
103 .pgo_haspage = vnode_pager_haspage,
104 };
105
106 int vnode_pbuf_freecnt;
107 int vnode_async_pbuf_freecnt;
108
109 /* Create the VM system backing object for this vnode */
110 int
111 vnode_create_vobject(struct vnode *vp, off_t isize, struct thread *td)
112 {
113 vm_object_t object;
114 vm_ooffset_t size = isize;
115 struct vattr va;
116
117 if (!vn_isdisk(vp, NULL) && vn_canvmio(vp) == FALSE)
118 return (0);
119
120 while ((object = vp->v_object) != NULL) {
121 VM_OBJECT_WLOCK(object);
122 if (!(object->flags & OBJ_DEAD)) {
123 VM_OBJECT_WUNLOCK(object);
124 return (0);
125 }
126 VOP_UNLOCK(vp, 0);
127 vm_object_set_flag(object, OBJ_DISCONNECTWNT);
128 VM_OBJECT_SLEEP(object, object, PDROP | PVM, "vodead", 0);
129 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
130 }
131
132 if (size == 0) {
133 if (vn_isdisk(vp, NULL)) {
134 size = IDX_TO_OFF(INT_MAX);
135 } else {
136 if (VOP_GETATTR(vp, &va, td->td_ucred))
137 return (0);
138 size = va.va_size;
139 }
140 }
141
142 object = vnode_pager_alloc(vp, size, 0, 0, td->td_ucred);
143 /*
144 * Dereference the reference we just created. This assumes
145 * that the object is associated with the vp.
146 */
147 VM_OBJECT_WLOCK(object);
148 object->ref_count--;
149 VM_OBJECT_WUNLOCK(object);
150 vrele(vp);
151
152 KASSERT(vp->v_object != NULL, ("vnode_create_vobject: NULL object"));
153
154 return (0);
155 }
156
157 void
158 vnode_destroy_vobject(struct vnode *vp)
159 {
160 struct vm_object *obj;
161
162 obj = vp->v_object;
163 if (obj == NULL)
164 return;
165 ASSERT_VOP_ELOCKED(vp, "vnode_destroy_vobject");
166 VM_OBJECT_WLOCK(obj);
167 umtx_shm_object_terminated(obj);
168 if (obj->ref_count == 0) {
169 /*
170 * don't double-terminate the object
171 */
172 if ((obj->flags & OBJ_DEAD) == 0) {
173 vm_object_terminate(obj);
174 } else {
175 /*
176 * Waiters were already handled during object
177 * termination. The exclusive vnode lock hopefully
178 * prevented new waiters from referencing the dying
179 * object.
180 */
181 KASSERT((obj->flags & OBJ_DISCONNECTWNT) == 0,
182 ("OBJ_DISCONNECTWNT set obj %p flags %x",
183 obj, obj->flags));
184 vp->v_object = NULL;
185 VM_OBJECT_WUNLOCK(obj);
186 }
187 } else {
188 /*
189 * Woe to the process that tries to page now :-).
190 */
191 vm_pager_deallocate(obj);
192 VM_OBJECT_WUNLOCK(obj);
193 }
194 KASSERT(vp->v_object == NULL, ("vp %p obj %p", vp, vp->v_object));
195 }
196
197
198 /*
199 * Allocate (or lookup) pager for a vnode.
200 * Handle is a vnode pointer.
201 *
202 * MPSAFE
203 */
204 vm_object_t
205 vnode_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
206 vm_ooffset_t offset, struct ucred *cred)
207 {
208 vm_object_t object;
209 struct vnode *vp;
210
211 /*
212 * Pageout to vnode, no can do yet.
213 */
214 if (handle == NULL)
215 return (NULL);
216
217 vp = (struct vnode *) handle;
218
219 /*
220 * If the object is being terminated, wait for it to
221 * go away.
222 */
223 retry:
224 while ((object = vp->v_object) != NULL) {
225 VM_OBJECT_WLOCK(object);
226 if ((object->flags & OBJ_DEAD) == 0)
227 break;
228 vm_object_set_flag(object, OBJ_DISCONNECTWNT);
229 VM_OBJECT_SLEEP(object, object, PDROP | PVM, "vadead", 0);
230 }
231
232 KASSERT(vp->v_usecount != 0, ("vnode_pager_alloc: no vnode reference"));
233
234 if (object == NULL) {
235 /*
236 * Add an object of the appropriate size
237 */
238 object = vm_object_allocate(OBJT_VNODE, OFF_TO_IDX(round_page(size)));
239
240 object->un_pager.vnp.vnp_size = size;
241 object->un_pager.vnp.writemappings = 0;
242
243 object->handle = handle;
244 VI_LOCK(vp);
245 if (vp->v_object != NULL) {
246 /*
247 * Object has been created while we were sleeping
248 */
249 VI_UNLOCK(vp);
250 VM_OBJECT_WLOCK(object);
251 KASSERT(object->ref_count == 1,
252 ("leaked ref %p %d", object, object->ref_count));
253 object->type = OBJT_DEAD;
254 object->ref_count = 0;
255 VM_OBJECT_WUNLOCK(object);
256 vm_object_destroy(object);
257 goto retry;
258 }
259 vp->v_object = object;
260 VI_UNLOCK(vp);
261 } else {
262 object->ref_count++;
263 #if VM_NRESERVLEVEL > 0
264 vm_object_color(object, 0);
265 #endif
266 VM_OBJECT_WUNLOCK(object);
267 }
268 vref(vp);
269 return (object);
270 }
271
272 /*
273 * The object must be locked.
274 */
275 static void
276 vnode_pager_dealloc(vm_object_t object)
277 {
278 struct vnode *vp;
279 int refs;
280
281 vp = object->handle;
282 if (vp == NULL)
283 panic("vnode_pager_dealloc: pager already dealloced");
284
285 VM_OBJECT_ASSERT_WLOCKED(object);
286 vm_object_pip_wait(object, "vnpdea");
287 refs = object->ref_count;
288
289 object->handle = NULL;
290 object->type = OBJT_DEAD;
291 if (object->flags & OBJ_DISCONNECTWNT) {
292 vm_object_clear_flag(object, OBJ_DISCONNECTWNT);
293 wakeup(object);
294 }
295 ASSERT_VOP_ELOCKED(vp, "vnode_pager_dealloc");
296 if (object->un_pager.vnp.writemappings > 0) {
297 object->un_pager.vnp.writemappings = 0;
298 VOP_ADD_WRITECOUNT(vp, -1);
299 CTR3(KTR_VFS, "%s: vp %p v_writecount decreased to %d",
300 __func__, vp, vp->v_writecount);
301 }
302 vp->v_object = NULL;
303 VOP_UNSET_TEXT(vp);
304 VM_OBJECT_WUNLOCK(object);
305 while (refs-- > 0)
306 vunref(vp);
307 VM_OBJECT_WLOCK(object);
308 }
309
310 static boolean_t
311 vnode_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
312 int *after)
313 {
314 struct vnode *vp = object->handle;
315 daddr_t bn;
316 int err;
317 daddr_t reqblock;
318 int poff;
319 int bsize;
320 int pagesperblock, blocksperpage;
321
322 VM_OBJECT_ASSERT_WLOCKED(object);
323 /*
324 * If no vp or vp is doomed or marked transparent to VM, we do not
325 * have the page.
326 */
327 if (vp == NULL || vp->v_iflag & VI_DOOMED)
328 return FALSE;
329 /*
330 * If the offset is beyond end of file we do
331 * not have the page.
332 */
333 if (IDX_TO_OFF(pindex) >= object->un_pager.vnp.vnp_size)
334 return FALSE;
335
336 bsize = vp->v_mount->mnt_stat.f_iosize;
337 pagesperblock = bsize / PAGE_SIZE;
338 blocksperpage = 0;
339 if (pagesperblock > 0) {
340 reqblock = pindex / pagesperblock;
341 } else {
342 blocksperpage = (PAGE_SIZE / bsize);
343 reqblock = pindex * blocksperpage;
344 }
345 VM_OBJECT_WUNLOCK(object);
346 err = VOP_BMAP(vp, reqblock, NULL, &bn, after, before);
347 VM_OBJECT_WLOCK(object);
348 if (err)
349 return TRUE;
350 if (bn == -1)
351 return FALSE;
352 if (pagesperblock > 0) {
353 poff = pindex - (reqblock * pagesperblock);
354 if (before) {
355 *before *= pagesperblock;
356 *before += poff;
357 }
358 if (after) {
359 /*
360 * The BMAP vop can report a partial block in the
361 * 'after', but must not report blocks after EOF.
362 * Assert the latter, and truncate 'after' in case
363 * of the former.
364 */
365 KASSERT((reqblock + *after) * pagesperblock <
366 roundup2(object->size, pagesperblock),
367 ("%s: reqblock %jd after %d size %ju", __func__,
368 (intmax_t )reqblock, *after,
369 (uintmax_t )object->size));
370 *after *= pagesperblock;
371 *after += pagesperblock - (poff + 1);
372 if (pindex + *after >= object->size)
373 *after = object->size - 1 - pindex;
374 }
375 } else {
376 if (before) {
377 *before /= blocksperpage;
378 }
379
380 if (after) {
381 *after /= blocksperpage;
382 }
383 }
384 return TRUE;
385 }
386
387 /*
388 * Lets the VM system know about a change in size for a file.
389 * We adjust our own internal size and flush any cached pages in
390 * the associated object that are affected by the size change.
391 *
392 * Note: this routine may be invoked as a result of a pager put
393 * operation (possibly at object termination time), so we must be careful.
394 */
395 void
396 vnode_pager_setsize(struct vnode *vp, vm_ooffset_t nsize)
397 {
398 vm_object_t object;
399 vm_page_t m;
400 vm_pindex_t nobjsize;
401
402 if ((object = vp->v_object) == NULL)
403 return;
404 /* ASSERT_VOP_ELOCKED(vp, "vnode_pager_setsize and not locked vnode"); */
405 VM_OBJECT_WLOCK(object);
406 if (object->type == OBJT_DEAD) {
407 VM_OBJECT_WUNLOCK(object);
408 return;
409 }
410 KASSERT(object->type == OBJT_VNODE,
411 ("not vnode-backed object %p", object));
412 if (nsize == object->un_pager.vnp.vnp_size) {
413 /*
414 * Hasn't changed size
415 */
416 VM_OBJECT_WUNLOCK(object);
417 return;
418 }
419 nobjsize = OFF_TO_IDX(nsize + PAGE_MASK);
420 if (nsize < object->un_pager.vnp.vnp_size) {
421 /*
422 * File has shrunk. Toss any cached pages beyond the new EOF.
423 */
424 if (nobjsize < object->size)
425 vm_object_page_remove(object, nobjsize, object->size,
426 0);
427 /*
428 * this gets rid of garbage at the end of a page that is now
429 * only partially backed by the vnode.
430 *
431 * XXX for some reason (I don't know yet), if we take a
432 * completely invalid page and mark it partially valid
433 * it can screw up NFS reads, so we don't allow the case.
434 */
435 if ((nsize & PAGE_MASK) &&
436 (m = vm_page_lookup(object, OFF_TO_IDX(nsize))) != NULL &&
437 m->valid != 0) {
438 int base = (int)nsize & PAGE_MASK;
439 int size = PAGE_SIZE - base;
440
441 /*
442 * Clear out partial-page garbage in case
443 * the page has been mapped.
444 */
445 pmap_zero_page_area(m, base, size);
446
447 /*
448 * Update the valid bits to reflect the blocks that
449 * have been zeroed. Some of these valid bits may
450 * have already been set.
451 */
452 vm_page_set_valid_range(m, base, size);
453
454 /*
455 * Round "base" to the next block boundary so that the
456 * dirty bit for a partially zeroed block is not
457 * cleared.
458 */
459 base = roundup2(base, DEV_BSIZE);
460
461 /*
462 * Clear out partial-page dirty bits.
463 *
464 * note that we do not clear out the valid
465 * bits. This would prevent bogus_page
466 * replacement from working properly.
467 */
468 vm_page_clear_dirty(m, base, PAGE_SIZE - base);
469 } else if ((nsize & PAGE_MASK) &&
470 vm_page_is_cached(object, OFF_TO_IDX(nsize))) {
471 vm_page_cache_free(object, OFF_TO_IDX(nsize),
472 nobjsize);
473 }
474 }
475 object->un_pager.vnp.vnp_size = nsize;
476 object->size = nobjsize;
477 VM_OBJECT_WUNLOCK(object);
478 }
479
480 /*
481 * calculate the linear (byte) disk address of specified virtual
482 * file address
483 */
484 static int
485 vnode_pager_addr(struct vnode *vp, vm_ooffset_t address, daddr_t *rtaddress,
486 int *run)
487 {
488 int bsize;
489 int err;
490 daddr_t vblock;
491 daddr_t voffset;
492
493 if (address < 0)
494 return -1;
495
496 if (vp->v_iflag & VI_DOOMED)
497 return -1;
498
499 bsize = vp->v_mount->mnt_stat.f_iosize;
500 vblock = address / bsize;
501 voffset = address % bsize;
502
503 err = VOP_BMAP(vp, vblock, NULL, rtaddress, run, NULL);
504 if (err == 0) {
505 if (*rtaddress != -1)
506 *rtaddress += voffset / DEV_BSIZE;
507 if (run) {
508 *run += 1;
509 *run *= bsize/PAGE_SIZE;
510 *run -= voffset/PAGE_SIZE;
511 }
512 }
513
514 return (err);
515 }
516
517 /*
518 * small block filesystem vnode pager input
519 */
520 static int
521 vnode_pager_input_smlfs(vm_object_t object, vm_page_t m)
522 {
523 struct vnode *vp;
524 struct bufobj *bo;
525 struct buf *bp;
526 struct sf_buf *sf;
527 daddr_t fileaddr;
528 vm_offset_t bsize;
529 vm_page_bits_t bits;
530 int error, i;
531
532 error = 0;
533 vp = object->handle;
534 if (vp->v_iflag & VI_DOOMED)
535 return VM_PAGER_BAD;
536
537 bsize = vp->v_mount->mnt_stat.f_iosize;
538
539 VOP_BMAP(vp, 0, &bo, 0, NULL, NULL);
540
541 sf = sf_buf_alloc(m, 0);
542
543 for (i = 0; i < PAGE_SIZE / bsize; i++) {
544 vm_ooffset_t address;
545
546 bits = vm_page_bits(i * bsize, bsize);
547 if (m->valid & bits)
548 continue;
549
550 address = IDX_TO_OFF(m->pindex) + i * bsize;
551 if (address >= object->un_pager.vnp.vnp_size) {
552 fileaddr = -1;
553 } else {
554 error = vnode_pager_addr(vp, address, &fileaddr, NULL);
555 if (error)
556 break;
557 }
558 if (fileaddr != -1) {
559 bp = getpbuf(&vnode_pbuf_freecnt);
560
561 /* build a minimal buffer header */
562 bp->b_iocmd = BIO_READ;
563 bp->b_iodone = bdone;
564 KASSERT(bp->b_rcred == NOCRED, ("leaking read ucred"));
565 KASSERT(bp->b_wcred == NOCRED, ("leaking write ucred"));
566 bp->b_rcred = crhold(curthread->td_ucred);
567 bp->b_wcred = crhold(curthread->td_ucred);
568 bp->b_data = (caddr_t)sf_buf_kva(sf) + i * bsize;
569 bp->b_blkno = fileaddr;
570 pbgetbo(bo, bp);
571 bp->b_vp = vp;
572 bp->b_bcount = bsize;
573 bp->b_bufsize = bsize;
574 bp->b_runningbufspace = bp->b_bufsize;
575 atomic_add_long(&runningbufspace, bp->b_runningbufspace);
576
577 /* do the input */
578 bp->b_iooffset = dbtob(bp->b_blkno);
579 bstrategy(bp);
580
581 bwait(bp, PVM, "vnsrd");
582
583 if ((bp->b_ioflags & BIO_ERROR) != 0)
584 error = EIO;
585
586 /*
587 * free the buffer header back to the swap buffer pool
588 */
589 bp->b_vp = NULL;
590 pbrelbo(bp);
591 relpbuf(bp, &vnode_pbuf_freecnt);
592 if (error)
593 break;
594 } else
595 bzero((caddr_t)sf_buf_kva(sf) + i * bsize, bsize);
596 KASSERT((m->dirty & bits) == 0,
597 ("vnode_pager_input_smlfs: page %p is dirty", m));
598 VM_OBJECT_WLOCK(object);
599 m->valid |= bits;
600 VM_OBJECT_WUNLOCK(object);
601 }
602 sf_buf_free(sf);
603 if (error) {
604 return VM_PAGER_ERROR;
605 }
606 return VM_PAGER_OK;
607 }
608
609 /*
610 * old style vnode pager input routine
611 */
612 static int
613 vnode_pager_input_old(vm_object_t object, vm_page_t m)
614 {
615 struct uio auio;
616 struct iovec aiov;
617 int error;
618 int size;
619 struct sf_buf *sf;
620 struct vnode *vp;
621
622 VM_OBJECT_ASSERT_WLOCKED(object);
623 error = 0;
624
625 /*
626 * Return failure if beyond current EOF
627 */
628 if (IDX_TO_OFF(m->pindex) >= object->un_pager.vnp.vnp_size) {
629 return VM_PAGER_BAD;
630 } else {
631 size = PAGE_SIZE;
632 if (IDX_TO_OFF(m->pindex) + size > object->un_pager.vnp.vnp_size)
633 size = object->un_pager.vnp.vnp_size - IDX_TO_OFF(m->pindex);
634 vp = object->handle;
635 VM_OBJECT_WUNLOCK(object);
636
637 /*
638 * Allocate a kernel virtual address and initialize so that
639 * we can use VOP_READ/WRITE routines.
640 */
641 sf = sf_buf_alloc(m, 0);
642
643 aiov.iov_base = (caddr_t)sf_buf_kva(sf);
644 aiov.iov_len = size;
645 auio.uio_iov = &aiov;
646 auio.uio_iovcnt = 1;
647 auio.uio_offset = IDX_TO_OFF(m->pindex);
648 auio.uio_segflg = UIO_SYSSPACE;
649 auio.uio_rw = UIO_READ;
650 auio.uio_resid = size;
651 auio.uio_td = curthread;
652
653 error = VOP_READ(vp, &auio, 0, curthread->td_ucred);
654 if (!error) {
655 int count = size - auio.uio_resid;
656
657 if (count == 0)
658 error = EINVAL;
659 else if (count != PAGE_SIZE)
660 bzero((caddr_t)sf_buf_kva(sf) + count,
661 PAGE_SIZE - count);
662 }
663 sf_buf_free(sf);
664
665 VM_OBJECT_WLOCK(object);
666 }
667 KASSERT(m->dirty == 0, ("vnode_pager_input_old: page %p is dirty", m));
668 if (!error)
669 m->valid = VM_PAGE_BITS_ALL;
670 return error ? VM_PAGER_ERROR : VM_PAGER_OK;
671 }
672
673 /*
674 * generic vnode pager input routine
675 */
676
677 /*
678 * Local media VFS's that do not implement their own VOP_GETPAGES
679 * should have their VOP_GETPAGES call to vnode_pager_generic_getpages()
680 * to implement the previous behaviour.
681 *
682 * All other FS's should use the bypass to get to the local media
683 * backing vp's VOP_GETPAGES.
684 */
685 static int
686 vnode_pager_getpages(vm_object_t object, vm_page_t *m, int count, int *rbehind,
687 int *rahead)
688 {
689 struct vnode *vp;
690 int rtval;
691
692 vp = object->handle;
693 VM_OBJECT_WUNLOCK(object);
694 rtval = VOP_GETPAGES(vp, m, count, rbehind, rahead);
695 KASSERT(rtval != EOPNOTSUPP,
696 ("vnode_pager: FS getpages not implemented\n"));
697 VM_OBJECT_WLOCK(object);
698 return rtval;
699 }
700
701 static int
702 vnode_pager_getpages_async(vm_object_t object, vm_page_t *m, int count,
703 int *rbehind, int *rahead, vop_getpages_iodone_t iodone, void *arg)
704 {
705 struct vnode *vp;
706 int rtval;
707
708 vp = object->handle;
709 VM_OBJECT_WUNLOCK(object);
710 rtval = VOP_GETPAGES_ASYNC(vp, m, count, rbehind, rahead, iodone, arg);
711 KASSERT(rtval != EOPNOTSUPP,
712 ("vnode_pager: FS getpages_async not implemented\n"));
713 VM_OBJECT_WLOCK(object);
714 return (rtval);
715 }
716
717 /*
718 * The implementation of VOP_GETPAGES() and VOP_GETPAGES_ASYNC() for
719 * local filesystems, where partially valid pages can only occur at
720 * the end of file.
721 */
722 int
723 vnode_pager_local_getpages(struct vop_getpages_args *ap)
724 {
725
726 return (vnode_pager_generic_getpages(ap->a_vp, ap->a_m, ap->a_count,
727 ap->a_rbehind, ap->a_rahead, NULL, NULL));
728 }
729
730 int
731 vnode_pager_local_getpages_async(struct vop_getpages_async_args *ap)
732 {
733
734 return (vnode_pager_generic_getpages(ap->a_vp, ap->a_m, ap->a_count,
735 ap->a_rbehind, ap->a_rahead, ap->a_iodone, ap->a_arg));
736 }
737
738 /*
739 * This is now called from local media FS's to operate against their
740 * own vnodes if they fail to implement VOP_GETPAGES.
741 */
742 int
743 vnode_pager_generic_getpages(struct vnode *vp, vm_page_t *m, int count,
744 int *a_rbehind, int *a_rahead, vop_getpages_iodone_t iodone, void *arg)
745 {
746 vm_object_t object;
747 struct bufobj *bo;
748 struct buf *bp;
749 off_t foff;
750 int bsize, pagesperblock, *freecnt;
751 int error, before, after, rbehind, rahead, poff, i;
752 int bytecount, secmask;
753
754 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK,
755 ("%s does not support devices", __func__));
756
757 if (vp->v_iflag & VI_DOOMED)
758 return (VM_PAGER_BAD);
759
760 object = vp->v_object;
761 foff = IDX_TO_OFF(m[0]->pindex);
762 bsize = vp->v_mount->mnt_stat.f_iosize;
763 pagesperblock = bsize / PAGE_SIZE;
764
765 KASSERT(foff < object->un_pager.vnp.vnp_size,
766 ("%s: page %p offset beyond vp %p size", __func__, m[0], vp));
767 KASSERT(count <= sizeof(bp->b_pages),
768 ("%s: requested %d pages", __func__, count));
769
770 /*
771 * The last page has valid blocks. Invalid part can only
772 * exist at the end of file, and the page is made fully valid
773 * by zeroing in vm_pager_get_pages().
774 */
775 if (m[count - 1]->valid != 0 && --count == 0) {
776 if (iodone != NULL)
777 iodone(arg, m, 1, 0);
778 return (VM_PAGER_OK);
779 }
780
781 /*
782 * Synchronous and asynchronous paging operations use different
783 * free pbuf counters. This is done to avoid asynchronous requests
784 * to consume all pbufs.
785 * Allocate the pbuf at the very beginning of the function, so that
786 * if we are low on certain kind of pbufs don't even proceed to BMAP,
787 * but sleep.
788 */
789 freecnt = iodone != NULL ?
790 &vnode_async_pbuf_freecnt : &vnode_pbuf_freecnt;
791 bp = getpbuf(freecnt);
792
793 /*
794 * Get the underlying device blocks for the file with VOP_BMAP().
795 * If the file system doesn't support VOP_BMAP, use old way of
796 * getting pages via VOP_READ.
797 */
798 error = VOP_BMAP(vp, foff / bsize, &bo, &bp->b_blkno, &after, &before);
799 if (error == EOPNOTSUPP) {
800 relpbuf(bp, freecnt);
801 VM_OBJECT_WLOCK(object);
802 for (i = 0; i < count; i++) {
803 PCPU_INC(cnt.v_vnodein);
804 PCPU_INC(cnt.v_vnodepgsin);
805 error = vnode_pager_input_old(object, m[i]);
806 if (error)
807 break;
808 }
809 VM_OBJECT_WUNLOCK(object);
810 return (error);
811 } else if (error != 0) {
812 relpbuf(bp, freecnt);
813 return (VM_PAGER_ERROR);
814 }
815
816 /*
817 * If the file system supports BMAP, but blocksize is smaller
818 * than a page size, then use special small filesystem code.
819 */
820 if (pagesperblock == 0) {
821 relpbuf(bp, freecnt);
822 for (i = 0; i < count; i++) {
823 PCPU_INC(cnt.v_vnodein);
824 PCPU_INC(cnt.v_vnodepgsin);
825 error = vnode_pager_input_smlfs(object, m[i]);
826 if (error)
827 break;
828 }
829 return (error);
830 }
831
832 /*
833 * A sparse file can be encountered only for a single page request,
834 * which may not be preceded by call to vm_pager_haspage().
835 */
836 if (bp->b_blkno == -1) {
837 KASSERT(count == 1,
838 ("%s: array[%d] request to a sparse file %p", __func__,
839 count, vp));
840 relpbuf(bp, freecnt);
841 pmap_zero_page(m[0]);
842 KASSERT(m[0]->dirty == 0, ("%s: page %p is dirty",
843 __func__, m[0]));
844 VM_OBJECT_WLOCK(object);
845 m[0]->valid = VM_PAGE_BITS_ALL;
846 VM_OBJECT_WUNLOCK(object);
847 return (VM_PAGER_OK);
848 }
849
850 bp->b_blkno += (foff % bsize) / DEV_BSIZE;
851
852 /* Recalculate blocks available after/before to pages. */
853 poff = (foff % bsize) / PAGE_SIZE;
854 before *= pagesperblock;
855 before += poff;
856 after *= pagesperblock;
857 after += pagesperblock - (poff + 1);
858 if (m[0]->pindex + after >= object->size)
859 after = object->size - 1 - m[0]->pindex;
860 KASSERT(count <= after + 1, ("%s: %d pages asked, can do only %d",
861 __func__, count, after + 1));
862 after -= count - 1;
863
864 /* Trim requested rbehind/rahead to possible values. */
865 rbehind = a_rbehind ? *a_rbehind : 0;
866 rahead = a_rahead ? *a_rahead : 0;
867 rbehind = min(rbehind, before);
868 rbehind = min(rbehind, m[0]->pindex);
869 rahead = min(rahead, after);
870 rahead = min(rahead, object->size - m[count - 1]->pindex);
871 KASSERT(rbehind + rahead + count <= sizeof(bp->b_pages),
872 ("%s: behind %d ahead %d count %d", __func__,
873 rbehind, rahead, count));
874
875 /*
876 * Fill in the bp->b_pages[] array with requested and optional
877 * read behind or read ahead pages. Read behind pages are looked
878 * up in a backward direction, down to a first cached page. Same
879 * for read ahead pages, but there is no need to shift the array
880 * in case of encountering a cached page.
881 */
882 i = bp->b_npages = 0;
883 if (rbehind) {
884 vm_pindex_t startpindex, tpindex;
885 vm_page_t p;
886
887 VM_OBJECT_WLOCK(object);
888 startpindex = m[0]->pindex - rbehind;
889 if ((p = TAILQ_PREV(m[0], pglist, listq)) != NULL &&
890 p->pindex >= startpindex)
891 startpindex = p->pindex + 1;
892
893 /* tpindex is unsigned; beware of numeric underflow. */
894 for (tpindex = m[0]->pindex - 1;
895 tpindex >= startpindex && tpindex < m[0]->pindex;
896 tpindex--, i++) {
897 p = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL |
898 VM_ALLOC_IFNOTCACHED);
899 if (p == NULL) {
900 /* Shift the array. */
901 for (int j = 0; j < i; j++)
902 bp->b_pages[j] = bp->b_pages[j +
903 tpindex + 1 - startpindex];
904 break;
905 }
906 bp->b_pages[tpindex - startpindex] = p;
907 }
908
909 bp->b_pgbefore = i;
910 bp->b_npages += i;
911 bp->b_blkno -= IDX_TO_OFF(i) / DEV_BSIZE;
912 } else
913 bp->b_pgbefore = 0;
914
915 /* Requested pages. */
916 for (int j = 0; j < count; j++, i++)
917 bp->b_pages[i] = m[j];
918 bp->b_npages += count;
919
920 if (rahead) {
921 vm_pindex_t endpindex, tpindex;
922 vm_page_t p;
923
924 if (!VM_OBJECT_WOWNED(object))
925 VM_OBJECT_WLOCK(object);
926 endpindex = m[count - 1]->pindex + rahead + 1;
927 if ((p = TAILQ_NEXT(m[count - 1], listq)) != NULL &&
928 p->pindex < endpindex)
929 endpindex = p->pindex;
930 if (endpindex > object->size)
931 endpindex = object->size;
932
933 for (tpindex = m[count - 1]->pindex + 1;
934 tpindex < endpindex; i++, tpindex++) {
935 p = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL |
936 VM_ALLOC_IFNOTCACHED);
937 if (p == NULL)
938 break;
939 bp->b_pages[i] = p;
940 }
941
942 bp->b_pgafter = i - bp->b_npages;
943 bp->b_npages = i;
944 } else
945 bp->b_pgafter = 0;
946
947 if (VM_OBJECT_WOWNED(object))
948 VM_OBJECT_WUNLOCK(object);
949
950 /* Report back actual behind/ahead read. */
951 if (a_rbehind)
952 *a_rbehind = bp->b_pgbefore;
953 if (a_rahead)
954 *a_rahead = bp->b_pgafter;
955
956 KASSERT(bp->b_npages <= sizeof(bp->b_pages),
957 ("%s: buf %p overflowed", __func__, bp));
958
959 /*
960 * Recalculate first offset and bytecount with regards to read behind.
961 * Truncate bytecount to vnode real size and round up physical size
962 * for real devices.
963 */
964 foff = IDX_TO_OFF(bp->b_pages[0]->pindex);
965 bytecount = bp->b_npages << PAGE_SHIFT;
966 if ((foff + bytecount) > object->un_pager.vnp.vnp_size)
967 bytecount = object->un_pager.vnp.vnp_size - foff;
968 secmask = bo->bo_bsize - 1;
969 KASSERT(secmask < PAGE_SIZE && secmask > 0,
970 ("%s: sector size %d too large", __func__, secmask + 1));
971 bytecount = (bytecount + secmask) & ~secmask;
972
973 /*
974 * And map the pages to be read into the kva, if the filesystem
975 * requires mapped buffers.
976 */
977 if ((vp->v_mount->mnt_kern_flag & MNTK_UNMAPPED_BUFS) != 0 &&
978 unmapped_buf_allowed) {
979 bp->b_data = unmapped_buf;
980 bp->b_offset = 0;
981 } else {
982 bp->b_data = bp->b_kvabase;
983 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages);
984 }
985
986 /* Build a minimal buffer header. */
987 bp->b_iocmd = BIO_READ;
988 KASSERT(bp->b_rcred == NOCRED, ("leaking read ucred"));
989 KASSERT(bp->b_wcred == NOCRED, ("leaking write ucred"));
990 bp->b_rcred = crhold(curthread->td_ucred);
991 bp->b_wcred = crhold(curthread->td_ucred);
992 pbgetbo(bo, bp);
993 bp->b_vp = vp;
994 bp->b_bcount = bp->b_bufsize = bp->b_runningbufspace = bytecount;
995 bp->b_iooffset = dbtob(bp->b_blkno);
996
997 atomic_add_long(&runningbufspace, bp->b_runningbufspace);
998 PCPU_INC(cnt.v_vnodein);
999 PCPU_ADD(cnt.v_vnodepgsin, bp->b_npages);
1000
1001 if (iodone != NULL) { /* async */
1002 bp->b_pgiodone = iodone;
1003 bp->b_caller1 = arg;
1004 bp->b_iodone = vnode_pager_generic_getpages_done_async;
1005 bp->b_flags |= B_ASYNC;
1006 BUF_KERNPROC(bp);
1007 bstrategy(bp);
1008 return (VM_PAGER_OK);
1009 } else {
1010 bp->b_iodone = bdone;
1011 bstrategy(bp);
1012 bwait(bp, PVM, "vnread");
1013 error = vnode_pager_generic_getpages_done(bp);
1014 for (i = 0; i < bp->b_npages; i++)
1015 bp->b_pages[i] = NULL;
1016 bp->b_vp = NULL;
1017 pbrelbo(bp);
1018 relpbuf(bp, &vnode_pbuf_freecnt);
1019 return (error != 0 ? VM_PAGER_ERROR : VM_PAGER_OK);
1020 }
1021 }
1022
1023 static void
1024 vnode_pager_generic_getpages_done_async(struct buf *bp)
1025 {
1026 int error;
1027
1028 error = vnode_pager_generic_getpages_done(bp);
1029 /* Run the iodone upon the requested range. */
1030 bp->b_pgiodone(bp->b_caller1, bp->b_pages + bp->b_pgbefore,
1031 bp->b_npages - bp->b_pgbefore - bp->b_pgafter, error);
1032 for (int i = 0; i < bp->b_npages; i++)
1033 bp->b_pages[i] = NULL;
1034 bp->b_vp = NULL;
1035 pbrelbo(bp);
1036 relpbuf(bp, &vnode_async_pbuf_freecnt);
1037 }
1038
1039 static int
1040 vnode_pager_generic_getpages_done(struct buf *bp)
1041 {
1042 vm_object_t object;
1043 off_t tfoff, nextoff;
1044 int i, error;
1045
1046 error = (bp->b_ioflags & BIO_ERROR) != 0 ? EIO : 0;
1047 object = bp->b_vp->v_object;
1048
1049 if (error == 0 && bp->b_bcount != bp->b_npages * PAGE_SIZE) {
1050 if (!buf_mapped(bp)) {
1051 bp->b_data = bp->b_kvabase;
1052 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages,
1053 bp->b_npages);
1054 }
1055 bzero(bp->b_data + bp->b_bcount,
1056 PAGE_SIZE * bp->b_npages - bp->b_bcount);
1057 }
1058 if (buf_mapped(bp)) {
1059 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages);
1060 bp->b_data = unmapped_buf;
1061 }
1062
1063 VM_OBJECT_WLOCK(object);
1064 for (i = 0, tfoff = IDX_TO_OFF(bp->b_pages[0]->pindex);
1065 i < bp->b_npages; i++, tfoff = nextoff) {
1066 vm_page_t mt;
1067
1068 nextoff = tfoff + PAGE_SIZE;
1069 mt = bp->b_pages[i];
1070
1071 if (nextoff <= object->un_pager.vnp.vnp_size) {
1072 /*
1073 * Read filled up entire page.
1074 */
1075 mt->valid = VM_PAGE_BITS_ALL;
1076 KASSERT(mt->dirty == 0,
1077 ("%s: page %p is dirty", __func__, mt));
1078 KASSERT(!pmap_page_is_mapped(mt),
1079 ("%s: page %p is mapped", __func__, mt));
1080 } else {
1081 /*
1082 * Read did not fill up entire page.
1083 *
1084 * Currently we do not set the entire page valid,
1085 * we just try to clear the piece that we couldn't
1086 * read.
1087 */
1088 vm_page_set_valid_range(mt, 0,
1089 object->un_pager.vnp.vnp_size - tfoff);
1090 KASSERT((mt->dirty & vm_page_bits(0,
1091 object->un_pager.vnp.vnp_size - tfoff)) == 0,
1092 ("%s: page %p is dirty", __func__, mt));
1093 }
1094
1095 if (i < bp->b_pgbefore || i >= bp->b_npages - bp->b_pgafter)
1096 vm_page_readahead_finish(mt);
1097 }
1098 VM_OBJECT_WUNLOCK(object);
1099 if (error != 0)
1100 printf("%s: I/O read error %d\n", __func__, error);
1101
1102 return (error);
1103 }
1104
1105 /*
1106 * EOPNOTSUPP is no longer legal. For local media VFS's that do not
1107 * implement their own VOP_PUTPAGES, their VOP_PUTPAGES should call to
1108 * vnode_pager_generic_putpages() to implement the previous behaviour.
1109 *
1110 * All other FS's should use the bypass to get to the local media
1111 * backing vp's VOP_PUTPAGES.
1112 */
1113 static void
1114 vnode_pager_putpages(vm_object_t object, vm_page_t *m, int count,
1115 int flags, int *rtvals)
1116 {
1117 int rtval;
1118 struct vnode *vp;
1119 int bytes = count * PAGE_SIZE;
1120
1121 /*
1122 * Force synchronous operation if we are extremely low on memory
1123 * to prevent a low-memory deadlock. VOP operations often need to
1124 * allocate more memory to initiate the I/O ( i.e. do a BMAP
1125 * operation ). The swapper handles the case by limiting the amount
1126 * of asynchronous I/O, but that sort of solution doesn't scale well
1127 * for the vnode pager without a lot of work.
1128 *
1129 * Also, the backing vnode's iodone routine may not wake the pageout
1130 * daemon up. This should be probably be addressed XXX.
1131 */
1132
1133 if (vm_cnt.v_free_count + vm_cnt.v_cache_count <
1134 vm_cnt.v_pageout_free_min)
1135 flags |= VM_PAGER_PUT_SYNC;
1136
1137 /*
1138 * Call device-specific putpages function
1139 */
1140 vp = object->handle;
1141 VM_OBJECT_WUNLOCK(object);
1142 rtval = VOP_PUTPAGES(vp, m, bytes, flags, rtvals);
1143 KASSERT(rtval != EOPNOTSUPP,
1144 ("vnode_pager: stale FS putpages\n"));
1145 VM_OBJECT_WLOCK(object);
1146 }
1147
1148
1149 /*
1150 * This is now called from local media FS's to operate against their
1151 * own vnodes if they fail to implement VOP_PUTPAGES.
1152 *
1153 * This is typically called indirectly via the pageout daemon and
1154 * clustering has already typically occurred, so in general we ask the
1155 * underlying filesystem to write the data out asynchronously rather
1156 * then delayed.
1157 */
1158 int
1159 vnode_pager_generic_putpages(struct vnode *vp, vm_page_t *ma, int bytecount,
1160 int flags, int *rtvals)
1161 {
1162 int i;
1163 vm_object_t object;
1164 vm_page_t m;
1165 int count;
1166
1167 int maxsize, ncount;
1168 vm_ooffset_t poffset;
1169 struct uio auio;
1170 struct iovec aiov;
1171 int error;
1172 int ioflags;
1173 int ppscheck = 0;
1174 static struct timeval lastfail;
1175 static int curfail;
1176
1177 object = vp->v_object;
1178 count = bytecount / PAGE_SIZE;
1179
1180 for (i = 0; i < count; i++)
1181 rtvals[i] = VM_PAGER_ERROR;
1182
1183 if ((int64_t)ma[0]->pindex < 0) {
1184 printf("vnode_pager_putpages: attempt to write meta-data!!! -- 0x%lx(%lx)\n",
1185 (long)ma[0]->pindex, (u_long)ma[0]->dirty);
1186 rtvals[0] = VM_PAGER_BAD;
1187 return VM_PAGER_BAD;
1188 }
1189
1190 maxsize = count * PAGE_SIZE;
1191 ncount = count;
1192
1193 poffset = IDX_TO_OFF(ma[0]->pindex);
1194
1195 /*
1196 * If the page-aligned write is larger then the actual file we
1197 * have to invalidate pages occurring beyond the file EOF. However,
1198 * there is an edge case where a file may not be page-aligned where
1199 * the last page is partially invalid. In this case the filesystem
1200 * may not properly clear the dirty bits for the entire page (which
1201 * could be VM_PAGE_BITS_ALL due to the page having been mmap()d).
1202 * With the page locked we are free to fix-up the dirty bits here.
1203 *
1204 * We do not under any circumstances truncate the valid bits, as
1205 * this will screw up bogus page replacement.
1206 */
1207 VM_OBJECT_WLOCK(object);
1208 if (maxsize + poffset > object->un_pager.vnp.vnp_size) {
1209 if (object->un_pager.vnp.vnp_size > poffset) {
1210 int pgoff;
1211
1212 maxsize = object->un_pager.vnp.vnp_size - poffset;
1213 ncount = btoc(maxsize);
1214 if ((pgoff = (int)maxsize & PAGE_MASK) != 0) {
1215 /*
1216 * If the object is locked and the following
1217 * conditions hold, then the page's dirty
1218 * field cannot be concurrently changed by a
1219 * pmap operation.
1220 */
1221 m = ma[ncount - 1];
1222 vm_page_assert_sbusied(m);
1223 KASSERT(!pmap_page_is_write_mapped(m),
1224 ("vnode_pager_generic_putpages: page %p is not read-only", m));
1225 vm_page_clear_dirty(m, pgoff, PAGE_SIZE -
1226 pgoff);
1227 }
1228 } else {
1229 maxsize = 0;
1230 ncount = 0;
1231 }
1232 if (ncount < count) {
1233 for (i = ncount; i < count; i++) {
1234 rtvals[i] = VM_PAGER_BAD;
1235 }
1236 }
1237 }
1238 VM_OBJECT_WUNLOCK(object);
1239
1240 /*
1241 * pageouts are already clustered, use IO_ASYNC to force a bawrite()
1242 * rather then a bdwrite() to prevent paging I/O from saturating
1243 * the buffer cache. Dummy-up the sequential heuristic to cause
1244 * large ranges to cluster. If neither IO_SYNC or IO_ASYNC is set,
1245 * the system decides how to cluster.
1246 */
1247 ioflags = IO_VMIO;
1248 if (flags & (VM_PAGER_PUT_SYNC | VM_PAGER_PUT_INVAL))
1249 ioflags |= IO_SYNC;
1250 else if ((flags & VM_PAGER_CLUSTER_OK) == 0)
1251 ioflags |= IO_ASYNC;
1252 ioflags |= (flags & VM_PAGER_PUT_INVAL) ? IO_INVAL: 0;
1253 ioflags |= IO_SEQMAX << IO_SEQSHIFT;
1254
1255 aiov.iov_base = (caddr_t) 0;
1256 aiov.iov_len = maxsize;
1257 auio.uio_iov = &aiov;
1258 auio.uio_iovcnt = 1;
1259 auio.uio_offset = poffset;
1260 auio.uio_segflg = UIO_NOCOPY;
1261 auio.uio_rw = UIO_WRITE;
1262 auio.uio_resid = maxsize;
1263 auio.uio_td = (struct thread *) 0;
1264 error = VOP_WRITE(vp, &auio, ioflags, curthread->td_ucred);
1265 PCPU_INC(cnt.v_vnodeout);
1266 PCPU_ADD(cnt.v_vnodepgsout, ncount);
1267
1268 if (error) {
1269 if ((ppscheck = ppsratecheck(&lastfail, &curfail, 1)))
1270 printf("vnode_pager_putpages: I/O error %d\n", error);
1271 }
1272 if (auio.uio_resid) {
1273 if (ppscheck || ppsratecheck(&lastfail, &curfail, 1))
1274 printf("vnode_pager_putpages: residual I/O %zd at %lu\n",
1275 auio.uio_resid, (u_long)ma[0]->pindex);
1276 }
1277 for (i = 0; i < ncount; i++) {
1278 rtvals[i] = VM_PAGER_OK;
1279 }
1280 return rtvals[0];
1281 }
1282
1283 void
1284 vnode_pager_undirty_pages(vm_page_t *ma, int *rtvals, int written)
1285 {
1286 vm_object_t obj;
1287 int i, pos;
1288
1289 if (written == 0)
1290 return;
1291 obj = ma[0]->object;
1292 VM_OBJECT_WLOCK(obj);
1293 for (i = 0, pos = 0; pos < written; i++, pos += PAGE_SIZE) {
1294 if (pos < trunc_page(written)) {
1295 rtvals[i] = VM_PAGER_OK;
1296 vm_page_undirty(ma[i]);
1297 } else {
1298 /* Partially written page. */
1299 rtvals[i] = VM_PAGER_AGAIN;
1300 vm_page_clear_dirty(ma[i], 0, written & PAGE_MASK);
1301 }
1302 }
1303 VM_OBJECT_WUNLOCK(obj);
1304 }
1305
1306 void
1307 vnode_pager_update_writecount(vm_object_t object, vm_offset_t start,
1308 vm_offset_t end)
1309 {
1310 struct vnode *vp;
1311 vm_ooffset_t old_wm;
1312
1313 VM_OBJECT_WLOCK(object);
1314 if (object->type != OBJT_VNODE) {
1315 VM_OBJECT_WUNLOCK(object);
1316 return;
1317 }
1318 old_wm = object->un_pager.vnp.writemappings;
1319 object->un_pager.vnp.writemappings += (vm_ooffset_t)end - start;
1320 vp = object->handle;
1321 if (old_wm == 0 && object->un_pager.vnp.writemappings != 0) {
1322 ASSERT_VOP_ELOCKED(vp, "v_writecount inc");
1323 VOP_ADD_WRITECOUNT(vp, 1);
1324 CTR3(KTR_VFS, "%s: vp %p v_writecount increased to %d",
1325 __func__, vp, vp->v_writecount);
1326 } else if (old_wm != 0 && object->un_pager.vnp.writemappings == 0) {
1327 ASSERT_VOP_ELOCKED(vp, "v_writecount dec");
1328 VOP_ADD_WRITECOUNT(vp, -1);
1329 CTR3(KTR_VFS, "%s: vp %p v_writecount decreased to %d",
1330 __func__, vp, vp->v_writecount);
1331 }
1332 VM_OBJECT_WUNLOCK(object);
1333 }
1334
1335 void
1336 vnode_pager_release_writecount(vm_object_t object, vm_offset_t start,
1337 vm_offset_t end)
1338 {
1339 struct vnode *vp;
1340 struct mount *mp;
1341 vm_offset_t inc;
1342
1343 VM_OBJECT_WLOCK(object);
1344
1345 /*
1346 * First, recheck the object type to account for the race when
1347 * the vnode is reclaimed.
1348 */
1349 if (object->type != OBJT_VNODE) {
1350 VM_OBJECT_WUNLOCK(object);
1351 return;
1352 }
1353
1354 /*
1355 * Optimize for the case when writemappings is not going to
1356 * zero.
1357 */
1358 inc = end - start;
1359 if (object->un_pager.vnp.writemappings != inc) {
1360 object->un_pager.vnp.writemappings -= inc;
1361 VM_OBJECT_WUNLOCK(object);
1362 return;
1363 }
1364
1365 vp = object->handle;
1366 vhold(vp);
1367 VM_OBJECT_WUNLOCK(object);
1368 mp = NULL;
1369 vn_start_write(vp, &mp, V_WAIT);
1370 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
1371
1372 /*
1373 * Decrement the object's writemappings, by swapping the start
1374 * and end arguments for vnode_pager_update_writecount(). If
1375 * there was not a race with vnode reclaimation, then the
1376 * vnode's v_writecount is decremented.
1377 */
1378 vnode_pager_update_writecount(object, end, start);
1379 VOP_UNLOCK(vp, 0);
1380 vdrop(vp);
1381 if (mp != NULL)
1382 vn_finished_write(mp);
1383 }
Cache object: f3ae7b053598430b1920e83e69c8b8a8
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