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("$FreeBSD$"); 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_local_getpages0(struct vnode *, vm_page_t *, int, int, 88 vop_getpages_iodone_t, void *); 89 static int vnode_pager_getpages(vm_object_t, vm_page_t *, int, int); 90 static int vnode_pager_getpages_async(vm_object_t, vm_page_t *, int, int, 91 vop_getpages_iodone_t, void *); 92 static void vnode_pager_putpages(vm_object_t, vm_page_t *, int, int, int *); 93 static boolean_t vnode_pager_haspage(vm_object_t, vm_pindex_t, int *, int *); 94 static vm_object_t vnode_pager_alloc(void *, vm_ooffset_t, vm_prot_t, 95 vm_ooffset_t, struct ucred *cred); 96 static int vnode_pager_generic_getpages_done(struct buf *); 97 static void vnode_pager_generic_getpages_done_async(struct buf *); 98 99 struct pagerops vnodepagerops = { 100 .pgo_alloc = vnode_pager_alloc, 101 .pgo_dealloc = vnode_pager_dealloc, 102 .pgo_getpages = vnode_pager_getpages, 103 .pgo_getpages_async = vnode_pager_getpages_async, 104 .pgo_putpages = vnode_pager_putpages, 105 .pgo_haspage = vnode_pager_haspage, 106 }; 107 108 int vnode_pbuf_freecnt; 109 int vnode_async_pbuf_freecnt; 110 111 /* Create the VM system backing object for this vnode */ 112 int 113 vnode_create_vobject(struct vnode *vp, off_t isize, struct thread *td) 114 { 115 vm_object_t object; 116 vm_ooffset_t size = isize; 117 struct vattr va; 118 119 if (!vn_isdisk(vp, NULL) && vn_canvmio(vp) == FALSE) 120 return (0); 121 122 while ((object = vp->v_object) != NULL) { 123 VM_OBJECT_WLOCK(object); 124 if (!(object->flags & OBJ_DEAD)) { 125 VM_OBJECT_WUNLOCK(object); 126 return (0); 127 } 128 VOP_UNLOCK(vp, 0); 129 vm_object_set_flag(object, OBJ_DISCONNECTWNT); 130 VM_OBJECT_SLEEP(object, object, PDROP | PVM, "vodead", 0); 131 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 132 } 133 134 if (size == 0) { 135 if (vn_isdisk(vp, NULL)) { 136 size = IDX_TO_OFF(INT_MAX); 137 } else { 138 if (VOP_GETATTR(vp, &va, td->td_ucred)) 139 return (0); 140 size = va.va_size; 141 } 142 } 143 144 object = vnode_pager_alloc(vp, size, 0, 0, td->td_ucred); 145 /* 146 * Dereference the reference we just created. This assumes 147 * that the object is associated with the vp. 148 */ 149 VM_OBJECT_WLOCK(object); 150 object->ref_count--; 151 VM_OBJECT_WUNLOCK(object); 152 vrele(vp); 153 154 KASSERT(vp->v_object != NULL, ("vnode_create_vobject: NULL object")); 155 156 return (0); 157 } 158 159 void 160 vnode_destroy_vobject(struct vnode *vp) 161 { 162 struct vm_object *obj; 163 164 obj = vp->v_object; 165 if (obj == NULL) 166 return; 167 ASSERT_VOP_ELOCKED(vp, "vnode_destroy_vobject"); 168 VM_OBJECT_WLOCK(obj); 169 if (obj->ref_count == 0) { 170 /* 171 * don't double-terminate the object 172 */ 173 if ((obj->flags & OBJ_DEAD) == 0) 174 vm_object_terminate(obj); 175 else 176 VM_OBJECT_WUNLOCK(obj); 177 } else { 178 /* 179 * Woe to the process that tries to page now :-). 180 */ 181 vm_pager_deallocate(obj); 182 VM_OBJECT_WUNLOCK(obj); 183 } 184 vp->v_object = NULL; 185 } 186 187 188 /* 189 * Allocate (or lookup) pager for a vnode. 190 * Handle is a vnode pointer. 191 * 192 * MPSAFE 193 */ 194 vm_object_t 195 vnode_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot, 196 vm_ooffset_t offset, struct ucred *cred) 197 { 198 vm_object_t object; 199 struct vnode *vp; 200 201 /* 202 * Pageout to vnode, no can do yet. 203 */ 204 if (handle == NULL) 205 return (NULL); 206 207 vp = (struct vnode *) handle; 208 209 /* 210 * If the object is being terminated, wait for it to 211 * go away. 212 */ 213 retry: 214 while ((object = vp->v_object) != NULL) { 215 VM_OBJECT_WLOCK(object); 216 if ((object->flags & OBJ_DEAD) == 0) 217 break; 218 vm_object_set_flag(object, OBJ_DISCONNECTWNT); 219 VM_OBJECT_SLEEP(object, object, PDROP | PVM, "vadead", 0); 220 } 221 222 KASSERT(vp->v_usecount != 0, ("vnode_pager_alloc: no vnode reference")); 223 224 if (object == NULL) { 225 /* 226 * Add an object of the appropriate size 227 */ 228 object = vm_object_allocate(OBJT_VNODE, OFF_TO_IDX(round_page(size))); 229 230 object->un_pager.vnp.vnp_size = size; 231 object->un_pager.vnp.writemappings = 0; 232 233 object->handle = handle; 234 VI_LOCK(vp); 235 if (vp->v_object != NULL) { 236 /* 237 * Object has been created while we were sleeping 238 */ 239 VI_UNLOCK(vp); 240 VM_OBJECT_WLOCK(object); 241 KASSERT(object->ref_count == 1, 242 ("leaked ref %p %d", object, object->ref_count)); 243 object->type = OBJT_DEAD; 244 object->ref_count = 0; 245 VM_OBJECT_WUNLOCK(object); 246 vm_object_destroy(object); 247 goto retry; 248 } 249 vp->v_object = object; 250 VI_UNLOCK(vp); 251 } else { 252 object->ref_count++; 253 #if VM_NRESERVLEVEL > 0 254 vm_object_color(object, 0); 255 #endif 256 VM_OBJECT_WUNLOCK(object); 257 } 258 vref(vp); 259 return (object); 260 } 261 262 /* 263 * The object must be locked. 264 */ 265 static void 266 vnode_pager_dealloc(vm_object_t object) 267 { 268 struct vnode *vp; 269 int refs; 270 271 vp = object->handle; 272 if (vp == NULL) 273 panic("vnode_pager_dealloc: pager already dealloced"); 274 275 VM_OBJECT_ASSERT_WLOCKED(object); 276 vm_object_pip_wait(object, "vnpdea"); 277 refs = object->ref_count; 278 279 object->handle = NULL; 280 object->type = OBJT_DEAD; 281 if (object->flags & OBJ_DISCONNECTWNT) { 282 vm_object_clear_flag(object, OBJ_DISCONNECTWNT); 283 wakeup(object); 284 } 285 ASSERT_VOP_ELOCKED(vp, "vnode_pager_dealloc"); 286 if (object->un_pager.vnp.writemappings > 0) { 287 object->un_pager.vnp.writemappings = 0; 288 VOP_ADD_WRITECOUNT(vp, -1); 289 CTR3(KTR_VFS, "%s: vp %p v_writecount decreased to %d", 290 __func__, vp, vp->v_writecount); 291 } 292 vp->v_object = NULL; 293 VOP_UNSET_TEXT(vp); 294 VM_OBJECT_WUNLOCK(object); 295 while (refs-- > 0) 296 vunref(vp); 297 VM_OBJECT_WLOCK(object); 298 } 299 300 static boolean_t 301 vnode_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before, 302 int *after) 303 { 304 struct vnode *vp = object->handle; 305 daddr_t bn; 306 int err; 307 daddr_t reqblock; 308 int poff; 309 int bsize; 310 int pagesperblock, blocksperpage; 311 312 VM_OBJECT_ASSERT_WLOCKED(object); 313 /* 314 * If no vp or vp is doomed or marked transparent to VM, we do not 315 * have the page. 316 */ 317 if (vp == NULL || vp->v_iflag & VI_DOOMED) 318 return FALSE; 319 /* 320 * If the offset is beyond end of file we do 321 * not have the page. 322 */ 323 if (IDX_TO_OFF(pindex) >= object->un_pager.vnp.vnp_size) 324 return FALSE; 325 326 bsize = vp->v_mount->mnt_stat.f_iosize; 327 pagesperblock = bsize / PAGE_SIZE; 328 blocksperpage = 0; 329 if (pagesperblock > 0) { 330 reqblock = pindex / pagesperblock; 331 } else { 332 blocksperpage = (PAGE_SIZE / bsize); 333 reqblock = pindex * blocksperpage; 334 } 335 VM_OBJECT_WUNLOCK(object); 336 err = VOP_BMAP(vp, reqblock, NULL, &bn, after, before); 337 VM_OBJECT_WLOCK(object); 338 if (err) 339 return TRUE; 340 if (bn == -1) 341 return FALSE; 342 if (pagesperblock > 0) { 343 poff = pindex - (reqblock * pagesperblock); 344 if (before) { 345 *before *= pagesperblock; 346 *before += poff; 347 } 348 if (after) { 349 /* 350 * The BMAP vop can report a partial block in the 351 * 'after', but must not report blocks after EOF. 352 * Assert the latter, and truncate 'after' in case 353 * of the former. 354 */ 355 KASSERT((reqblock + *after) * pagesperblock < 356 roundup2(object->size, pagesperblock), 357 ("%s: reqblock %jd after %d size %ju", __func__, 358 (intmax_t )reqblock, *after, 359 (uintmax_t )object->size)); 360 *after *= pagesperblock; 361 *after += pagesperblock - (poff + 1); 362 if (pindex + *after >= object->size) 363 *after = object->size - 1 - pindex; 364 } 365 } else { 366 if (before) { 367 *before /= blocksperpage; 368 } 369 370 if (after) { 371 *after /= blocksperpage; 372 } 373 } 374 return TRUE; 375 } 376 377 /* 378 * Lets the VM system know about a change in size for a file. 379 * We adjust our own internal size and flush any cached pages in 380 * the associated object that are affected by the size change. 381 * 382 * Note: this routine may be invoked as a result of a pager put 383 * operation (possibly at object termination time), so we must be careful. 384 */ 385 void 386 vnode_pager_setsize(struct vnode *vp, vm_ooffset_t nsize) 387 { 388 vm_object_t object; 389 vm_page_t m; 390 vm_pindex_t nobjsize; 391 392 if ((object = vp->v_object) == NULL) 393 return; 394 /* ASSERT_VOP_ELOCKED(vp, "vnode_pager_setsize and not locked vnode"); */ 395 VM_OBJECT_WLOCK(object); 396 if (object->type == OBJT_DEAD) { 397 VM_OBJECT_WUNLOCK(object); 398 return; 399 } 400 KASSERT(object->type == OBJT_VNODE, 401 ("not vnode-backed object %p", object)); 402 if (nsize == object->un_pager.vnp.vnp_size) { 403 /* 404 * Hasn't changed size 405 */ 406 VM_OBJECT_WUNLOCK(object); 407 return; 408 } 409 nobjsize = OFF_TO_IDX(nsize + PAGE_MASK); 410 if (nsize < object->un_pager.vnp.vnp_size) { 411 /* 412 * File has shrunk. Toss any cached pages beyond the new EOF. 413 */ 414 if (nobjsize < object->size) 415 vm_object_page_remove(object, nobjsize, object->size, 416 0); 417 /* 418 * this gets rid of garbage at the end of a page that is now 419 * only partially backed by the vnode. 420 * 421 * XXX for some reason (I don't know yet), if we take a 422 * completely invalid page and mark it partially valid 423 * it can screw up NFS reads, so we don't allow the case. 424 */ 425 if ((nsize & PAGE_MASK) && 426 (m = vm_page_lookup(object, OFF_TO_IDX(nsize))) != NULL && 427 m->valid != 0) { 428 int base = (int)nsize & PAGE_MASK; 429 int size = PAGE_SIZE - base; 430 431 /* 432 * Clear out partial-page garbage in case 433 * the page has been mapped. 434 */ 435 pmap_zero_page_area(m, base, size); 436 437 /* 438 * Update the valid bits to reflect the blocks that 439 * have been zeroed. Some of these valid bits may 440 * have already been set. 441 */ 442 vm_page_set_valid_range(m, base, size); 443 444 /* 445 * Round "base" to the next block boundary so that the 446 * dirty bit for a partially zeroed block is not 447 * cleared. 448 */ 449 base = roundup2(base, DEV_BSIZE); 450 451 /* 452 * Clear out partial-page dirty bits. 453 * 454 * note that we do not clear out the valid 455 * bits. This would prevent bogus_page 456 * replacement from working properly. 457 */ 458 vm_page_clear_dirty(m, base, PAGE_SIZE - base); 459 } else if ((nsize & PAGE_MASK) && 460 vm_page_is_cached(object, OFF_TO_IDX(nsize))) { 461 vm_page_cache_free(object, OFF_TO_IDX(nsize), 462 nobjsize); 463 } 464 } 465 object->un_pager.vnp.vnp_size = nsize; 466 object->size = nobjsize; 467 VM_OBJECT_WUNLOCK(object); 468 } 469 470 /* 471 * calculate the linear (byte) disk address of specified virtual 472 * file address 473 */ 474 static int 475 vnode_pager_addr(struct vnode *vp, vm_ooffset_t address, daddr_t *rtaddress, 476 int *run) 477 { 478 int bsize; 479 int err; 480 daddr_t vblock; 481 daddr_t voffset; 482 483 if (address < 0) 484 return -1; 485 486 if (vp->v_iflag & VI_DOOMED) 487 return -1; 488 489 bsize = vp->v_mount->mnt_stat.f_iosize; 490 vblock = address / bsize; 491 voffset = address % bsize; 492 493 err = VOP_BMAP(vp, vblock, NULL, rtaddress, run, NULL); 494 if (err == 0) { 495 if (*rtaddress != -1) 496 *rtaddress += voffset / DEV_BSIZE; 497 if (run) { 498 *run += 1; 499 *run *= bsize/PAGE_SIZE; 500 *run -= voffset/PAGE_SIZE; 501 } 502 } 503 504 return (err); 505 } 506 507 /* 508 * small block filesystem vnode pager input 509 */ 510 static int 511 vnode_pager_input_smlfs(vm_object_t object, vm_page_t m) 512 { 513 struct vnode *vp; 514 struct bufobj *bo; 515 struct buf *bp; 516 struct sf_buf *sf; 517 daddr_t fileaddr; 518 vm_offset_t bsize; 519 vm_page_bits_t bits; 520 int error, i; 521 522 error = 0; 523 vp = object->handle; 524 if (vp->v_iflag & VI_DOOMED) 525 return VM_PAGER_BAD; 526 527 bsize = vp->v_mount->mnt_stat.f_iosize; 528 529 VOP_BMAP(vp, 0, &bo, 0, NULL, NULL); 530 531 sf = sf_buf_alloc(m, 0); 532 533 for (i = 0; i < PAGE_SIZE / bsize; i++) { 534 vm_ooffset_t address; 535 536 bits = vm_page_bits(i * bsize, bsize); 537 if (m->valid & bits) 538 continue; 539 540 address = IDX_TO_OFF(m->pindex) + i * bsize; 541 if (address >= object->un_pager.vnp.vnp_size) { 542 fileaddr = -1; 543 } else { 544 error = vnode_pager_addr(vp, address, &fileaddr, NULL); 545 if (error) 546 break; 547 } 548 if (fileaddr != -1) { 549 bp = getpbuf(&vnode_pbuf_freecnt); 550 551 /* build a minimal buffer header */ 552 bp->b_iocmd = BIO_READ; 553 bp->b_iodone = bdone; 554 KASSERT(bp->b_rcred == NOCRED, ("leaking read ucred")); 555 KASSERT(bp->b_wcred == NOCRED, ("leaking write ucred")); 556 bp->b_rcred = crhold(curthread->td_ucred); 557 bp->b_wcred = crhold(curthread->td_ucred); 558 bp->b_data = (caddr_t)sf_buf_kva(sf) + i * bsize; 559 bp->b_blkno = fileaddr; 560 pbgetbo(bo, bp); 561 bp->b_vp = vp; 562 bp->b_bcount = bsize; 563 bp->b_bufsize = bsize; 564 bp->b_runningbufspace = bp->b_bufsize; 565 atomic_add_long(&runningbufspace, bp->b_runningbufspace); 566 567 /* do the input */ 568 bp->b_iooffset = dbtob(bp->b_blkno); 569 bstrategy(bp); 570 571 bwait(bp, PVM, "vnsrd"); 572 573 if ((bp->b_ioflags & BIO_ERROR) != 0) 574 error = EIO; 575 576 /* 577 * free the buffer header back to the swap buffer pool 578 */ 579 bp->b_vp = NULL; 580 pbrelbo(bp); 581 relpbuf(bp, &vnode_pbuf_freecnt); 582 if (error) 583 break; 584 } else 585 bzero((caddr_t)sf_buf_kva(sf) + i * bsize, bsize); 586 KASSERT((m->dirty & bits) == 0, 587 ("vnode_pager_input_smlfs: page %p is dirty", m)); 588 VM_OBJECT_WLOCK(object); 589 m->valid |= bits; 590 VM_OBJECT_WUNLOCK(object); 591 } 592 sf_buf_free(sf); 593 if (error) { 594 return VM_PAGER_ERROR; 595 } 596 return VM_PAGER_OK; 597 } 598 599 /* 600 * old style vnode pager input routine 601 */ 602 static int 603 vnode_pager_input_old(vm_object_t object, vm_page_t m) 604 { 605 struct uio auio; 606 struct iovec aiov; 607 int error; 608 int size; 609 struct sf_buf *sf; 610 struct vnode *vp; 611 612 VM_OBJECT_ASSERT_WLOCKED(object); 613 error = 0; 614 615 /* 616 * Return failure if beyond current EOF 617 */ 618 if (IDX_TO_OFF(m->pindex) >= object->un_pager.vnp.vnp_size) { 619 return VM_PAGER_BAD; 620 } else { 621 size = PAGE_SIZE; 622 if (IDX_TO_OFF(m->pindex) + size > object->un_pager.vnp.vnp_size) 623 size = object->un_pager.vnp.vnp_size - IDX_TO_OFF(m->pindex); 624 vp = object->handle; 625 VM_OBJECT_WUNLOCK(object); 626 627 /* 628 * Allocate a kernel virtual address and initialize so that 629 * we can use VOP_READ/WRITE routines. 630 */ 631 sf = sf_buf_alloc(m, 0); 632 633 aiov.iov_base = (caddr_t)sf_buf_kva(sf); 634 aiov.iov_len = size; 635 auio.uio_iov = &aiov; 636 auio.uio_iovcnt = 1; 637 auio.uio_offset = IDX_TO_OFF(m->pindex); 638 auio.uio_segflg = UIO_SYSSPACE; 639 auio.uio_rw = UIO_READ; 640 auio.uio_resid = size; 641 auio.uio_td = curthread; 642 643 error = VOP_READ(vp, &auio, 0, curthread->td_ucred); 644 if (!error) { 645 int count = size - auio.uio_resid; 646 647 if (count == 0) 648 error = EINVAL; 649 else if (count != PAGE_SIZE) 650 bzero((caddr_t)sf_buf_kva(sf) + count, 651 PAGE_SIZE - count); 652 } 653 sf_buf_free(sf); 654 655 VM_OBJECT_WLOCK(object); 656 } 657 KASSERT(m->dirty == 0, ("vnode_pager_input_old: page %p is dirty", m)); 658 if (!error) 659 m->valid = VM_PAGE_BITS_ALL; 660 return error ? VM_PAGER_ERROR : VM_PAGER_OK; 661 } 662 663 /* 664 * generic vnode pager input routine 665 */ 666 667 /* 668 * Local media VFS's that do not implement their own VOP_GETPAGES 669 * should have their VOP_GETPAGES call to vnode_pager_generic_getpages() 670 * to implement the previous behaviour. 671 * 672 * All other FS's should use the bypass to get to the local media 673 * backing vp's VOP_GETPAGES. 674 */ 675 static int 676 vnode_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage) 677 { 678 int rtval; 679 struct vnode *vp; 680 int bytes = count * PAGE_SIZE; 681 682 vp = object->handle; 683 VM_OBJECT_WUNLOCK(object); 684 rtval = VOP_GETPAGES(vp, m, bytes, reqpage); 685 KASSERT(rtval != EOPNOTSUPP, 686 ("vnode_pager: FS getpages not implemented\n")); 687 VM_OBJECT_WLOCK(object); 688 return rtval; 689 } 690 691 static int 692 vnode_pager_getpages_async(vm_object_t object, vm_page_t *m, int count, 693 int reqpage, vop_getpages_iodone_t iodone, void *arg) 694 { 695 struct vnode *vp; 696 int rtval; 697 698 vp = object->handle; 699 VM_OBJECT_WUNLOCK(object); 700 rtval = VOP_GETPAGES_ASYNC(vp, m, count * PAGE_SIZE, reqpage, 701 iodone, arg); 702 KASSERT(rtval != EOPNOTSUPP, 703 ("vnode_pager: FS getpages_async not implemented\n")); 704 VM_OBJECT_WLOCK(object); 705 return (rtval); 706 } 707 708 /* 709 * The implementation of VOP_GETPAGES() and VOP_GETPAGES_ASYNC() for 710 * local filesystems, where partially valid pages can only occur at 711 * the end of file. 712 */ 713 int 714 vnode_pager_local_getpages(struct vop_getpages_args *ap) 715 { 716 717 return (vnode_pager_local_getpages0(ap->a_vp, ap->a_m, ap->a_count, 718 ap->a_reqpage, NULL, NULL)); 719 } 720 721 int 722 vnode_pager_local_getpages_async(struct vop_getpages_async_args *ap) 723 { 724 725 return (vnode_pager_local_getpages0(ap->a_vp, ap->a_m, ap->a_count, 726 ap->a_reqpage, ap->a_iodone, ap->a_arg)); 727 } 728 729 static int 730 vnode_pager_local_getpages0(struct vnode *vp, vm_page_t *m, int bytecount, 731 int reqpage, vop_getpages_iodone_t iodone, void *arg) 732 { 733 vm_page_t mreq; 734 735 mreq = m[reqpage]; 736 737 /* 738 * Since the caller has busied the requested page, that page's valid 739 * field will not be changed by other threads. 740 */ 741 vm_page_assert_xbusied(mreq); 742 743 /* 744 * The requested page has valid blocks. Invalid part can only 745 * exist at the end of file, and the page is made fully valid 746 * by zeroing in vm_pager_get_pages(). Free non-requested 747 * pages, since no i/o is done to read its content. 748 */ 749 if (mreq->valid != 0) { 750 vm_pager_free_nonreq(mreq->object, m, reqpage, 751 round_page(bytecount) / PAGE_SIZE, FALSE); 752 if (iodone != NULL) 753 iodone(arg, m, reqpage, 0); 754 return (VM_PAGER_OK); 755 } 756 757 return (vnode_pager_generic_getpages(vp, m, bytecount, reqpage, 758 iodone, arg)); 759 } 760 761 /* 762 * This is now called from local media FS's to operate against their 763 * own vnodes if they fail to implement VOP_GETPAGES. 764 */ 765 int 766 vnode_pager_generic_getpages(struct vnode *vp, vm_page_t *m, int bytecount, 767 int reqpage, vop_getpages_iodone_t iodone, void *arg) 768 { 769 vm_object_t object; 770 struct bufobj *bo; 771 struct buf *bp; 772 daddr_t firstaddr, reqblock; 773 off_t foff; 774 int pbefore, pafter, i, size, bsize, first, last, *freecnt; 775 int count, error, before, after, secmask; 776 777 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 778 ("vnode_pager_generic_getpages does not support devices")); 779 if (vp->v_iflag & VI_DOOMED) 780 return (VM_PAGER_BAD); 781 782 object = vp->v_object; 783 count = bytecount / PAGE_SIZE; 784 bsize = vp->v_mount->mnt_stat.f_iosize; 785 786 /* 787 * Synchronous and asynchronous paging operations use different 788 * free pbuf counters. This is done to avoid asynchronous requests 789 * to consume all pbufs. 790 * Allocate the pbuf at the very beginning of the function, so that 791 * if we are low on certain kind of pbufs don't even proceed to BMAP, 792 * but sleep. 793 */ 794 freecnt = iodone != NULL ? 795 &vnode_async_pbuf_freecnt : &vnode_pbuf_freecnt; 796 bp = getpbuf(freecnt); 797 798 /* 799 * Get the underlying device blocks for the file with VOP_BMAP(). 800 * If the file system doesn't support VOP_BMAP, use old way of 801 * getting pages via VOP_READ. 802 */ 803 error = VOP_BMAP(vp, IDX_TO_OFF(m[reqpage]->pindex) / bsize, &bo, 804 &reqblock, &after, &before); 805 if (error == EOPNOTSUPP) { 806 relpbuf(bp, freecnt); 807 VM_OBJECT_WLOCK(object); 808 for (i = 0; i < count; i++) 809 if (i != reqpage) { 810 vm_page_lock(m[i]); 811 vm_page_free(m[i]); 812 vm_page_unlock(m[i]); 813 } 814 PCPU_INC(cnt.v_vnodein); 815 PCPU_INC(cnt.v_vnodepgsin); 816 error = vnode_pager_input_old(object, m[reqpage]); 817 VM_OBJECT_WUNLOCK(object); 818 return (error); 819 } else if (error != 0) { 820 relpbuf(bp, freecnt); 821 vm_pager_free_nonreq(object, m, reqpage, count, FALSE); 822 return (VM_PAGER_ERROR); 823 824 /* 825 * If the blocksize is smaller than a page size, then use 826 * special small filesystem code. 827 */ 828 } else if ((PAGE_SIZE / bsize) > 1) { 829 relpbuf(bp, freecnt); 830 vm_pager_free_nonreq(object, m, reqpage, count, FALSE); 831 PCPU_INC(cnt.v_vnodein); 832 PCPU_INC(cnt.v_vnodepgsin); 833 return (vnode_pager_input_smlfs(object, m[reqpage])); 834 } 835 836 /* 837 * Since the caller has busied the requested page, that page's valid 838 * field will not be changed by other threads. 839 */ 840 vm_page_assert_xbusied(m[reqpage]); 841 842 /* 843 * If we have a completely valid page available to us, we can 844 * clean up and return. Otherwise we have to re-read the 845 * media. 846 */ 847 if (m[reqpage]->valid == VM_PAGE_BITS_ALL) { 848 relpbuf(bp, freecnt); 849 vm_pager_free_nonreq(object, m, reqpage, count, FALSE); 850 return (VM_PAGER_OK); 851 } else if (reqblock == -1) { 852 relpbuf(bp, freecnt); 853 pmap_zero_page(m[reqpage]); 854 KASSERT(m[reqpage]->dirty == 0, 855 ("vnode_pager_generic_getpages: page %p is dirty", m)); 856 VM_OBJECT_WLOCK(object); 857 m[reqpage]->valid = VM_PAGE_BITS_ALL; 858 vm_pager_free_nonreq(object, m, reqpage, count, TRUE); 859 VM_OBJECT_WUNLOCK(object); 860 return (VM_PAGER_OK); 861 } else if (m[reqpage]->valid != 0) { 862 VM_OBJECT_WLOCK(object); 863 m[reqpage]->valid = 0; 864 VM_OBJECT_WUNLOCK(object); 865 } 866 867 pbefore = (daddr_t)before * bsize / PAGE_SIZE; 868 pafter = (daddr_t)after * bsize / PAGE_SIZE; 869 first = reqpage < pbefore ? 0 : reqpage - pbefore; 870 last = reqpage + pafter >= count ? count - 1 : reqpage + pafter; 871 if (first > 0 || last + 1 < count) { 872 VM_OBJECT_WLOCK(object); 873 for (i = 0; i < first; i++) { 874 vm_page_lock(m[i]); 875 vm_page_free(m[i]); 876 vm_page_unlock(m[i]); 877 } 878 for (i = last + 1; i < count; i++) { 879 vm_page_lock(m[i]); 880 vm_page_free(m[i]); 881 vm_page_unlock(m[i]); 882 } 883 VM_OBJECT_WUNLOCK(object); 884 } 885 886 /* 887 * here on direct device I/O 888 */ 889 firstaddr = reqblock; 890 firstaddr += (IDX_TO_OFF(m[reqpage]->pindex) % bsize) / DEV_BSIZE; 891 firstaddr -= IDX_TO_OFF(reqpage - first) / DEV_BSIZE; 892 893 /* 894 * The first and last page have been calculated now, move 895 * input pages to be zero based, and adjust the count. 896 */ 897 m += first; 898 reqpage -= first; 899 count = last - first + 1; 900 901 /* 902 * calculate the file virtual address for the transfer 903 */ 904 foff = IDX_TO_OFF(m[0]->pindex); 905 906 /* 907 * calculate the size of the transfer 908 */ 909 size = count * PAGE_SIZE; 910 KASSERT(count > 0, ("zero count")); 911 if ((foff + size) > object->un_pager.vnp.vnp_size) 912 size = object->un_pager.vnp.vnp_size - foff; 913 KASSERT(size > 0, ("zero size")); 914 915 /* 916 * round up physical size for real devices. 917 */ 918 secmask = bo->bo_bsize - 1; 919 KASSERT(secmask < PAGE_SIZE && secmask > 0, 920 ("vnode_pager_generic_getpages: sector size %d too large", 921 secmask + 1)); 922 size = (size + secmask) & ~secmask; 923 924 /* 925 * and map the pages to be read into the kva, if the filesystem 926 * requires mapped buffers. 927 */ 928 if ((vp->v_mount->mnt_kern_flag & MNTK_UNMAPPED_BUFS) != 0 && 929 unmapped_buf_allowed) { 930 bp->b_data = unmapped_buf; 931 bp->b_offset = 0; 932 } else { 933 bp->b_data = bp->b_kvabase; 934 pmap_qenter((vm_offset_t)bp->b_data, m, count); 935 } 936 937 /* build a minimal buffer header */ 938 bp->b_iocmd = BIO_READ; 939 KASSERT(bp->b_rcred == NOCRED, ("leaking read ucred")); 940 KASSERT(bp->b_wcred == NOCRED, ("leaking write ucred")); 941 bp->b_rcred = crhold(curthread->td_ucred); 942 bp->b_wcred = crhold(curthread->td_ucred); 943 bp->b_blkno = firstaddr; 944 pbgetbo(bo, bp); 945 bp->b_vp = vp; 946 bp->b_bcount = size; 947 bp->b_bufsize = size; 948 bp->b_runningbufspace = bp->b_bufsize; 949 for (i = 0; i < count; i++) 950 bp->b_pages[i] = m[i]; 951 bp->b_npages = count; 952 bp->b_pager.pg_reqpage = reqpage; 953 atomic_add_long(&runningbufspace, bp->b_runningbufspace); 954 955 PCPU_INC(cnt.v_vnodein); 956 PCPU_ADD(cnt.v_vnodepgsin, count); 957 958 /* do the input */ 959 bp->b_iooffset = dbtob(bp->b_blkno); 960 961 if (iodone != NULL) { /* async */ 962 bp->b_pager.pg_iodone = iodone; 963 bp->b_caller1 = arg; 964 bp->b_iodone = vnode_pager_generic_getpages_done_async; 965 bp->b_flags |= B_ASYNC; 966 BUF_KERNPROC(bp); 967 bstrategy(bp); 968 /* Good bye! */ 969 } else { 970 bp->b_iodone = bdone; 971 bstrategy(bp); 972 bwait(bp, PVM, "vnread"); 973 error = vnode_pager_generic_getpages_done(bp); 974 for (i = 0; i < bp->b_npages; i++) 975 bp->b_pages[i] = NULL; 976 bp->b_vp = NULL; 977 pbrelbo(bp); 978 relpbuf(bp, &vnode_pbuf_freecnt); 979 } 980 981 return (error != 0 ? VM_PAGER_ERROR : VM_PAGER_OK); 982 } 983 984 static void 985 vnode_pager_generic_getpages_done_async(struct buf *bp) 986 { 987 int error; 988 989 error = vnode_pager_generic_getpages_done(bp); 990 bp->b_pager.pg_iodone(bp->b_caller1, bp->b_pages, 991 bp->b_pager.pg_reqpage, error); 992 for (int i = 0; i < bp->b_npages; i++) 993 bp->b_pages[i] = NULL; 994 bp->b_vp = NULL; 995 pbrelbo(bp); 996 relpbuf(bp, &vnode_async_pbuf_freecnt); 997 } 998 999 static int 1000 vnode_pager_generic_getpages_done(struct buf *bp) 1001 { 1002 vm_object_t object; 1003 off_t tfoff, nextoff; 1004 int i, error; 1005 1006 error = (bp->b_ioflags & BIO_ERROR) != 0 ? EIO : 0; 1007 object = bp->b_vp->v_object; 1008 1009 if (error == 0 && bp->b_bcount != bp->b_npages * PAGE_SIZE) { 1010 if (!buf_mapped(bp)) { 1011 bp->b_data = bp->b_kvabase; 1012 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, 1013 bp->b_npages); 1014 } 1015 bzero(bp->b_data + bp->b_bcount, 1016 PAGE_SIZE * bp->b_npages - bp->b_bcount); 1017 } 1018 if (buf_mapped(bp)) { 1019 pmap_qremove((vm_offset_t)bp->b_data, bp->b_npages); 1020 bp->b_data = unmapped_buf; 1021 } 1022 1023 VM_OBJECT_WLOCK(object); 1024 for (i = 0, tfoff = IDX_TO_OFF(bp->b_pages[0]->pindex); 1025 i < bp->b_npages; i++, tfoff = nextoff) { 1026 vm_page_t mt; 1027 1028 nextoff = tfoff + PAGE_SIZE; 1029 mt = bp->b_pages[i]; 1030 1031 if (nextoff <= object->un_pager.vnp.vnp_size) { 1032 /* 1033 * Read filled up entire page. 1034 */ 1035 mt->valid = VM_PAGE_BITS_ALL; 1036 KASSERT(mt->dirty == 0, 1037 ("%s: page %p is dirty", __func__, mt)); 1038 KASSERT(!pmap_page_is_mapped(mt), 1039 ("%s: page %p is mapped", __func__, mt)); 1040 } else { 1041 /* 1042 * Read did not fill up entire page. 1043 * 1044 * Currently we do not set the entire page valid, 1045 * we just try to clear the piece that we couldn't 1046 * read. 1047 */ 1048 vm_page_set_valid_range(mt, 0, 1049 object->un_pager.vnp.vnp_size - tfoff); 1050 KASSERT((mt->dirty & vm_page_bits(0, 1051 object->un_pager.vnp.vnp_size - tfoff)) == 0, 1052 ("%s: page %p is dirty", __func__, mt)); 1053 } 1054 1055 if (i != bp->b_pager.pg_reqpage) 1056 vm_page_readahead_finish(mt); 1057 } 1058 VM_OBJECT_WUNLOCK(object); 1059 if (error != 0) 1060 printf("%s: I/O read error %d\n", __func__, error); 1061 1062 return (error); 1063 } 1064 1065 /* 1066 * EOPNOTSUPP is no longer legal. For local media VFS's that do not 1067 * implement their own VOP_PUTPAGES, their VOP_PUTPAGES should call to 1068 * vnode_pager_generic_putpages() to implement the previous behaviour. 1069 * 1070 * All other FS's should use the bypass to get to the local media 1071 * backing vp's VOP_PUTPAGES. 1072 */ 1073 static void 1074 vnode_pager_putpages(vm_object_t object, vm_page_t *m, int count, 1075 int flags, int *rtvals) 1076 { 1077 int rtval; 1078 struct vnode *vp; 1079 int bytes = count * PAGE_SIZE; 1080 1081 /* 1082 * Force synchronous operation if we are extremely low on memory 1083 * to prevent a low-memory deadlock. VOP operations often need to 1084 * allocate more memory to initiate the I/O ( i.e. do a BMAP 1085 * operation ). The swapper handles the case by limiting the amount 1086 * of asynchronous I/O, but that sort of solution doesn't scale well 1087 * for the vnode pager without a lot of work. 1088 * 1089 * Also, the backing vnode's iodone routine may not wake the pageout 1090 * daemon up. This should be probably be addressed XXX. 1091 */ 1092 1093 if (vm_cnt.v_free_count + vm_cnt.v_cache_count < 1094 vm_cnt.v_pageout_free_min) 1095 flags |= VM_PAGER_PUT_SYNC; 1096 1097 /* 1098 * Call device-specific putpages function 1099 */ 1100 vp = object->handle; 1101 VM_OBJECT_WUNLOCK(object); 1102 rtval = VOP_PUTPAGES(vp, m, bytes, flags, rtvals); 1103 KASSERT(rtval != EOPNOTSUPP, 1104 ("vnode_pager: stale FS putpages\n")); 1105 VM_OBJECT_WLOCK(object); 1106 } 1107 1108 1109 /* 1110 * This is now called from local media FS's to operate against their 1111 * own vnodes if they fail to implement VOP_PUTPAGES. 1112 * 1113 * This is typically called indirectly via the pageout daemon and 1114 * clustering has already typically occured, so in general we ask the 1115 * underlying filesystem to write the data out asynchronously rather 1116 * then delayed. 1117 */ 1118 int 1119 vnode_pager_generic_putpages(struct vnode *vp, vm_page_t *ma, int bytecount, 1120 int flags, int *rtvals) 1121 { 1122 int i; 1123 vm_object_t object; 1124 vm_page_t m; 1125 int count; 1126 1127 int maxsize, ncount; 1128 vm_ooffset_t poffset; 1129 struct uio auio; 1130 struct iovec aiov; 1131 int error; 1132 int ioflags; 1133 int ppscheck = 0; 1134 static struct timeval lastfail; 1135 static int curfail; 1136 1137 object = vp->v_object; 1138 count = bytecount / PAGE_SIZE; 1139 1140 for (i = 0; i < count; i++) 1141 rtvals[i] = VM_PAGER_ERROR; 1142 1143 if ((int64_t)ma[0]->pindex < 0) { 1144 printf("vnode_pager_putpages: attempt to write meta-data!!! -- 0x%lx(%lx)\n", 1145 (long)ma[0]->pindex, (u_long)ma[0]->dirty); 1146 rtvals[0] = VM_PAGER_BAD; 1147 return VM_PAGER_BAD; 1148 } 1149 1150 maxsize = count * PAGE_SIZE; 1151 ncount = count; 1152 1153 poffset = IDX_TO_OFF(ma[0]->pindex); 1154 1155 /* 1156 * If the page-aligned write is larger then the actual file we 1157 * have to invalidate pages occuring beyond the file EOF. However, 1158 * there is an edge case where a file may not be page-aligned where 1159 * the last page is partially invalid. In this case the filesystem 1160 * may not properly clear the dirty bits for the entire page (which 1161 * could be VM_PAGE_BITS_ALL due to the page having been mmap()d). 1162 * With the page locked we are free to fix-up the dirty bits here. 1163 * 1164 * We do not under any circumstances truncate the valid bits, as 1165 * this will screw up bogus page replacement. 1166 */ 1167 VM_OBJECT_WLOCK(object); 1168 if (maxsize + poffset > object->un_pager.vnp.vnp_size) { 1169 if (object->un_pager.vnp.vnp_size > poffset) { 1170 int pgoff; 1171 1172 maxsize = object->un_pager.vnp.vnp_size - poffset; 1173 ncount = btoc(maxsize); 1174 if ((pgoff = (int)maxsize & PAGE_MASK) != 0) { 1175 /* 1176 * If the object is locked and the following 1177 * conditions hold, then the page's dirty 1178 * field cannot be concurrently changed by a 1179 * pmap operation. 1180 */ 1181 m = ma[ncount - 1]; 1182 vm_page_assert_sbusied(m); 1183 KASSERT(!pmap_page_is_write_mapped(m), 1184 ("vnode_pager_generic_putpages: page %p is not read-only", m)); 1185 vm_page_clear_dirty(m, pgoff, PAGE_SIZE - 1186 pgoff); 1187 } 1188 } else { 1189 maxsize = 0; 1190 ncount = 0; 1191 } 1192 if (ncount < count) { 1193 for (i = ncount; i < count; i++) { 1194 rtvals[i] = VM_PAGER_BAD; 1195 } 1196 } 1197 } 1198 VM_OBJECT_WUNLOCK(object); 1199 1200 /* 1201 * pageouts are already clustered, use IO_ASYNC to force a bawrite() 1202 * rather then a bdwrite() to prevent paging I/O from saturating 1203 * the buffer cache. Dummy-up the sequential heuristic to cause 1204 * large ranges to cluster. If neither IO_SYNC or IO_ASYNC is set, 1205 * the system decides how to cluster. 1206 */ 1207 ioflags = IO_VMIO; 1208 if (flags & (VM_PAGER_PUT_SYNC | VM_PAGER_PUT_INVAL)) 1209 ioflags |= IO_SYNC; 1210 else if ((flags & VM_PAGER_CLUSTER_OK) == 0) 1211 ioflags |= IO_ASYNC; 1212 ioflags |= (flags & VM_PAGER_PUT_INVAL) ? IO_INVAL: 0; 1213 ioflags |= IO_SEQMAX << IO_SEQSHIFT; 1214 1215 aiov.iov_base = (caddr_t) 0; 1216 aiov.iov_len = maxsize; 1217 auio.uio_iov = &aiov; 1218 auio.uio_iovcnt = 1; 1219 auio.uio_offset = poffset; 1220 auio.uio_segflg = UIO_NOCOPY; 1221 auio.uio_rw = UIO_WRITE; 1222 auio.uio_resid = maxsize; 1223 auio.uio_td = (struct thread *) 0; 1224 error = VOP_WRITE(vp, &auio, ioflags, curthread->td_ucred); 1225 PCPU_INC(cnt.v_vnodeout); 1226 PCPU_ADD(cnt.v_vnodepgsout, ncount); 1227 1228 if (error) { 1229 if ((ppscheck = ppsratecheck(&lastfail, &curfail, 1))) 1230 printf("vnode_pager_putpages: I/O error %d\n", error); 1231 } 1232 if (auio.uio_resid) { 1233 if (ppscheck || ppsratecheck(&lastfail, &curfail, 1)) 1234 printf("vnode_pager_putpages: residual I/O %zd at %lu\n", 1235 auio.uio_resid, (u_long)ma[0]->pindex); 1236 } 1237 for (i = 0; i < ncount; i++) { 1238 rtvals[i] = VM_PAGER_OK; 1239 } 1240 return rtvals[0]; 1241 } 1242 1243 void 1244 vnode_pager_undirty_pages(vm_page_t *ma, int *rtvals, int written) 1245 { 1246 vm_object_t obj; 1247 int i, pos; 1248 1249 if (written == 0) 1250 return; 1251 obj = ma[0]->object; 1252 VM_OBJECT_WLOCK(obj); 1253 for (i = 0, pos = 0; pos < written; i++, pos += PAGE_SIZE) { 1254 if (pos < trunc_page(written)) { 1255 rtvals[i] = VM_PAGER_OK; 1256 vm_page_undirty(ma[i]); 1257 } else { 1258 /* Partially written page. */ 1259 rtvals[i] = VM_PAGER_AGAIN; 1260 vm_page_clear_dirty(ma[i], 0, written & PAGE_MASK); 1261 } 1262 } 1263 VM_OBJECT_WUNLOCK(obj); 1264 } 1265 1266 void 1267 vnode_pager_update_writecount(vm_object_t object, vm_offset_t start, 1268 vm_offset_t end) 1269 { 1270 struct vnode *vp; 1271 vm_ooffset_t old_wm; 1272 1273 VM_OBJECT_WLOCK(object); 1274 if (object->type != OBJT_VNODE) { 1275 VM_OBJECT_WUNLOCK(object); 1276 return; 1277 } 1278 old_wm = object->un_pager.vnp.writemappings; 1279 object->un_pager.vnp.writemappings += (vm_ooffset_t)end - start; 1280 vp = object->handle; 1281 if (old_wm == 0 && object->un_pager.vnp.writemappings != 0) { 1282 ASSERT_VOP_ELOCKED(vp, "v_writecount inc"); 1283 VOP_ADD_WRITECOUNT(vp, 1); 1284 CTR3(KTR_VFS, "%s: vp %p v_writecount increased to %d", 1285 __func__, vp, vp->v_writecount); 1286 } else if (old_wm != 0 && object->un_pager.vnp.writemappings == 0) { 1287 ASSERT_VOP_ELOCKED(vp, "v_writecount dec"); 1288 VOP_ADD_WRITECOUNT(vp, -1); 1289 CTR3(KTR_VFS, "%s: vp %p v_writecount decreased to %d", 1290 __func__, vp, vp->v_writecount); 1291 } 1292 VM_OBJECT_WUNLOCK(object); 1293 } 1294 1295 void 1296 vnode_pager_release_writecount(vm_object_t object, vm_offset_t start, 1297 vm_offset_t end) 1298 { 1299 struct vnode *vp; 1300 struct mount *mp; 1301 vm_offset_t inc; 1302 1303 VM_OBJECT_WLOCK(object); 1304 1305 /* 1306 * First, recheck the object type to account for the race when 1307 * the vnode is reclaimed. 1308 */ 1309 if (object->type != OBJT_VNODE) { 1310 VM_OBJECT_WUNLOCK(object); 1311 return; 1312 } 1313 1314 /* 1315 * Optimize for the case when writemappings is not going to 1316 * zero. 1317 */ 1318 inc = end - start; 1319 if (object->un_pager.vnp.writemappings != inc) { 1320 object->un_pager.vnp.writemappings -= inc; 1321 VM_OBJECT_WUNLOCK(object); 1322 return; 1323 } 1324 1325 vp = object->handle; 1326 vhold(vp); 1327 VM_OBJECT_WUNLOCK(object); 1328 mp = NULL; 1329 vn_start_write(vp, &mp, V_WAIT); 1330 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 1331 1332 /* 1333 * Decrement the object's writemappings, by swapping the start 1334 * and end arguments for vnode_pager_update_writecount(). If 1335 * there was not a race with vnode reclaimation, then the 1336 * vnode's v_writecount is decremented. 1337 */ 1338 vnode_pager_update_writecount(object, end, start); 1339 VOP_UNLOCK(vp, 0); 1340 vdrop(vp); 1341 if (mp != NULL) 1342 vn_finished_write(mp); 1343 } 1344