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