1 /* 2 * (MPSAFE) 3 * 4 * Copyright (c) 1990 University of Utah. 5 * Copyright (c) 1991 The Regents of the University of California. 6 * All rights reserved. 7 * Copyright (c) 1993, 1994 John S. Dyson 8 * Copyright (c) 1995, David Greenman 9 * 10 * This code is derived from software contributed to Berkeley by 11 * the Systems Programming Group of the University of Utah Computer 12 * Science Department. 13 * 14 * Redistribution and use in source and binary forms, with or without 15 * modification, are permitted provided that the following conditions 16 * are met: 17 * 1. Redistributions of source code must retain the above copyright 18 * notice, this list of conditions and the following disclaimer. 19 * 2. Redistributions in binary form must reproduce the above copyright 20 * notice, this list of conditions and the following disclaimer in the 21 * documentation and/or other materials provided with the distribution. 22 * 3. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 * 38 * from: @(#)vnode_pager.c 7.5 (Berkeley) 4/20/91 39 * $FreeBSD: src/sys/vm/vnode_pager.c,v 1.116.2.7 2002/12/31 09:34:51 dillon Exp $ 40 */ 41 42 /* 43 * Page to/from files (vnodes). 44 */ 45 46 /* 47 * TODO: 48 * Implement VOP_GETPAGES/PUTPAGES interface for filesystems. Will 49 * greatly re-simplify the vnode_pager. 50 */ 51 52 #include <sys/param.h> 53 #include <sys/systm.h> 54 #include <sys/uio.h> 55 #include <sys/kernel.h> 56 #include <sys/proc.h> 57 #include <sys/vnode.h> 58 #include <sys/mount.h> 59 #include <sys/buf.h> 60 #include <sys/vmmeter.h> 61 #include <sys/conf.h> 62 63 #include <cpu/lwbuf.h> 64 65 #include <vm/vm.h> 66 #include <vm/vm_object.h> 67 #include <vm/vm_page.h> 68 #include <vm/vm_pager.h> 69 #include <vm/vm_map.h> 70 #include <vm/vnode_pager.h> 71 #include <vm/swap_pager.h> 72 #include <vm/vm_extern.h> 73 74 #include <vm/vm_page2.h> 75 76 static void vnode_pager_dealloc (vm_object_t); 77 static int vnode_pager_getpage (vm_object_t, vm_page_t *, int); 78 static void vnode_pager_putpages (vm_object_t, vm_page_t *, int, int, int *); 79 static boolean_t vnode_pager_haspage (vm_object_t, vm_pindex_t); 80 81 struct pagerops vnodepagerops = { 82 vnode_pager_dealloc, 83 vnode_pager_getpage, 84 vnode_pager_putpages, 85 vnode_pager_haspage 86 }; 87 88 static struct krate vbadrate = { 1 }; 89 static struct krate vresrate = { 1 }; 90 91 long vnode_pbuf_freecnt = -1; /* start out unlimited */ 92 93 /* 94 * Allocate a VM object for a vnode, typically a regular file vnode. 95 * 96 * Some additional information is required to generate a properly sized 97 * object which covers the entire buffer cache buffer straddling the file 98 * EOF. Userland does not see the extra pages as the VM fault code tests 99 * against v_filesize. 100 */ 101 vm_object_t 102 vnode_pager_alloc(void *handle, off_t length, vm_prot_t prot, off_t offset, 103 int blksize, int boff) 104 { 105 vm_object_t object; 106 struct vnode *vp; 107 off_t loffset; 108 vm_pindex_t lsize; 109 110 /* 111 * Pageout to vnode, no can do yet. 112 */ 113 if (handle == NULL) 114 return (NULL); 115 116 /* 117 * XXX hack - This initialization should be put somewhere else. 118 */ 119 if (vnode_pbuf_freecnt < 0) { 120 vnode_pbuf_freecnt = nswbuf_kva / 2 + 1; 121 } 122 123 /* 124 * Serialize potential vnode/object teardowns and interlocks 125 */ 126 vp = (struct vnode *)handle; 127 lwkt_gettoken(&vp->v_token); 128 129 /* 130 * If the object is being terminated, wait for it to 131 * go away. 132 */ 133 object = vp->v_object; 134 if (object) { 135 vm_object_hold(object); 136 KKASSERT((object->flags & OBJ_DEAD) == 0); 137 } 138 139 if (VREFCNT(vp) <= 0) 140 panic("vnode_pager_alloc: no vnode reference"); 141 142 /* 143 * Round up to the *next* block, then destroy the buffers in question. 144 * Since we are only removing some of the buffers we must rely on the 145 * scan count to determine whether a loop is necessary. 146 * 147 * Destroy any pages beyond the last buffer. 148 */ 149 if (boff < 0) 150 boff = (int)(length % blksize); 151 if (boff) 152 loffset = length + (blksize - boff); 153 else 154 loffset = length; 155 lsize = OFF_TO_IDX(round_page64(loffset)); 156 157 if (object == NULL) { 158 /* 159 * And an object of the appropriate size 160 */ 161 object = vm_object_allocate_hold(OBJT_VNODE, lsize); 162 object->handle = handle; 163 vp->v_object = object; 164 vp->v_filesize = length; 165 if (vp->v_mount && (vp->v_mount->mnt_kern_flag & MNTK_NOMSYNC)) 166 vm_object_set_flag(object, OBJ_NOMSYNC); 167 vref(vp); 168 } else { 169 vm_object_reference_quick(object); /* also vref's */ 170 if (object->size != lsize) { 171 kprintf("vnode_pager_alloc: Warning, objsize " 172 "mismatch %jd/%jd vp=%p obj=%p\n", 173 (intmax_t)object->size, 174 (intmax_t)lsize, 175 vp, object); 176 } 177 if (vp->v_filesize != length) { 178 kprintf("vnode_pager_alloc: Warning, filesize " 179 "mismatch %jd/%jd vp=%p obj=%p\n", 180 (intmax_t)vp->v_filesize, 181 (intmax_t)length, 182 vp, object); 183 } 184 } 185 vm_object_drop(object); 186 lwkt_reltoken(&vp->v_token); 187 188 return (object); 189 } 190 191 /* 192 * Add a ref to a vnode's existing VM object, return the object or 193 * NULL if the vnode did not have one. This does not create the 194 * object (we can't since we don't know what the proper blocksize/boff 195 * is to match the VFS's use of the buffer cache). 196 * 197 * The vnode must be referenced and is typically open. The object should 198 * be stable in this situation. 199 * 200 * Returns the object with an additional reference but not locked. 201 */ 202 vm_object_t 203 vnode_pager_reference(struct vnode *vp) 204 { 205 vm_object_t object; 206 207 if ((object = vp->v_object) != NULL) 208 vm_object_reference_quick(object); /* also vref's vnode */ 209 return (object); 210 } 211 212 static void 213 vnode_pager_dealloc(vm_object_t object) 214 { 215 struct vnode *vp = object->handle; 216 217 if (vp == NULL) 218 panic("vnode_pager_dealloc: pager already dealloced"); 219 220 vm_object_pip_wait(object, "vnpdea"); 221 222 object->handle = NULL; 223 object->type = OBJT_DEAD; 224 vp->v_object = NULL; 225 vp->v_filesize = NOOFFSET; 226 vclrflags(vp, VTEXT | VOBJBUF); 227 swap_pager_freespace_all(object); 228 } 229 230 /* 231 * Return whether the vnode pager has the requested page. 232 */ 233 static boolean_t 234 vnode_pager_haspage(vm_object_t object, vm_pindex_t pindex) 235 { 236 struct vnode *vp = object->handle; 237 off_t loffset; 238 off_t doffset; 239 int voff; 240 int bsize; 241 int error; 242 243 /* 244 * If no vp or vp is doomed or marked transparent to VM, we do not 245 * have the page. 246 */ 247 if ((vp == NULL) || (vp->v_flag & VRECLAIMED)) 248 return FALSE; 249 250 /* 251 * If filesystem no longer mounted or offset beyond end of file we do 252 * not have the page. 253 */ 254 loffset = IDX_TO_OFF(pindex); 255 256 if (vp->v_mount == NULL || loffset >= vp->v_filesize) 257 return FALSE; 258 259 bsize = vp->v_mount->mnt_stat.f_iosize; 260 voff = loffset % bsize; 261 262 /* 263 * XXX (obsolete - before and after pointers are now NULL) 264 * 265 * BMAP returns byte counts before and after, where after 266 * is inclusive of the base page. haspage must return page 267 * counts before and after where after does not include the 268 * base page. 269 * 270 * BMAP is allowed to return a *after of 0 for backwards 271 * compatibility. The base page is still considered valid if 272 * no error is returned. 273 */ 274 error = VOP_BMAP(vp, loffset - voff, &doffset, NULL, NULL, 0); 275 if (error) 276 return TRUE; 277 if (doffset == NOOFFSET) 278 return FALSE; 279 return TRUE; 280 } 281 282 /* 283 * Lets the VM system know about a change in size for a file. 284 * We adjust our own internal size and flush any cached pages in 285 * the associated object that are affected by the size change. 286 * 287 * NOTE: This routine may be invoked as a result of a pager put 288 * operation (possibly at object termination time), so we must be careful. 289 * 290 * NOTE: vp->v_filesize is initialized to NOOFFSET (-1), be sure that 291 * we do not blow up on the case. nsize will always be >= 0, however. 292 */ 293 void 294 vnode_pager_setsize(struct vnode *vp, vm_ooffset_t nsize) 295 { 296 vm_pindex_t nobjsize; 297 vm_pindex_t oobjsize; 298 vm_object_t object; 299 300 object = vp->v_object; 301 if (object == NULL) 302 return; 303 vm_object_hold(object); 304 KKASSERT(vp->v_object == object); 305 306 /* 307 * Hasn't changed size 308 */ 309 if (nsize == vp->v_filesize) { 310 vm_object_drop(object); 311 return; 312 } 313 314 /* 315 * Has changed size. Adjust the VM object's size and v_filesize 316 * before we start scanning pages to prevent new pages from being 317 * allocated during the scan. 318 */ 319 nobjsize = OFF_TO_IDX(nsize + PAGE_MASK); 320 oobjsize = object->size; 321 object->size = nobjsize; 322 323 /* 324 * File has shrunk. Toss any cached pages beyond the new EOF. 325 */ 326 if (nsize < vp->v_filesize) { 327 vp->v_filesize = nsize; 328 if (nobjsize < oobjsize) { 329 vm_object_page_remove(object, nobjsize, oobjsize, 330 FALSE); 331 } 332 /* 333 * This gets rid of garbage at the end of a page that is now 334 * only partially backed by the vnode. Since we are setting 335 * the entire page valid & clean after we are done we have 336 * to be sure that the portion of the page within the file 337 * bounds is already valid. If it isn't then making it 338 * valid would create a corrupt block. 339 */ 340 if (nsize & PAGE_MASK) { 341 vm_offset_t kva; 342 vm_page_t m; 343 344 m = vm_page_lookup_busy_wait(object, OFF_TO_IDX(nsize), 345 TRUE, "vsetsz"); 346 347 if (m && m->valid) { 348 int base = (int)nsize & PAGE_MASK; 349 int size = PAGE_SIZE - base; 350 struct lwbuf *lwb; 351 struct lwbuf lwb_cache; 352 353 /* 354 * Clear out partial-page garbage in case 355 * the page has been mapped. 356 * 357 * This is byte aligned. 358 */ 359 lwb = lwbuf_alloc(m, &lwb_cache); 360 kva = lwbuf_kva(lwb); 361 bzero((caddr_t)kva + base, size); 362 lwbuf_free(lwb); 363 364 /* 365 * XXX work around SMP data integrity race 366 * by unmapping the page from user processes. 367 * The garbage we just cleared may be mapped 368 * to a user process running on another cpu 369 * and this code is not running through normal 370 * I/O channels which handle SMP issues for 371 * us, so unmap page to synchronize all cpus. 372 * 373 * XXX should vm_pager_unmap_page() have 374 * dealt with this? 375 */ 376 vm_page_protect(m, VM_PROT_NONE); 377 378 /* 379 * Clear out partial-page dirty bits. This 380 * has the side effect of setting the valid 381 * bits, but that is ok. There are a bunch 382 * of places in the VM system where we expected 383 * m->dirty == VM_PAGE_BITS_ALL. The file EOF 384 * case is one of them. If the page is still 385 * partially dirty, make it fully dirty. 386 * 387 * NOTE: We do not clear out the valid 388 * bits. This would prevent bogus_page 389 * replacement from working properly. 390 * 391 * NOTE: We do not want to clear the dirty 392 * bit for a partial DEV_BSIZE'd truncation! 393 * This is DEV_BSIZE aligned! 394 */ 395 vm_page_clear_dirty_beg_nonincl(m, base, size); 396 if (m->dirty != 0) 397 m->dirty = VM_PAGE_BITS_ALL; 398 vm_page_wakeup(m); 399 } else if (m) { 400 vm_page_wakeup(m); 401 } 402 } 403 } else { 404 vp->v_filesize = nsize; 405 } 406 vm_object_drop(object); 407 } 408 409 /* 410 * Release a page busied for a getpages operation. The page may have become 411 * wired (typically due to being used by the buffer cache) or otherwise been 412 * soft-busied and cannot be freed in that case. A held page can still be 413 * freed. 414 */ 415 void 416 vnode_pager_freepage(vm_page_t m) 417 { 418 if ((m->busy_count & PBUSY_MASK) || 419 m->wire_count || 420 (m->flags & PG_NEED_COMMIT)) { 421 vm_page_activate(m); 422 vm_page_wakeup(m); 423 } else { 424 vm_page_free(m); 425 } 426 } 427 428 /* 429 * EOPNOTSUPP is no longer legal. For local media VFS's that do not 430 * implement their own VOP_GETPAGES, their VOP_GETPAGES should call to 431 * vnode_pager_generic_getpages() to implement the previous behaviour. 432 * 433 * All other FS's should use the bypass to get to the local media 434 * backing vp's VOP_GETPAGES. 435 */ 436 static int 437 vnode_pager_getpage(vm_object_t object, vm_page_t *mpp, int seqaccess) 438 { 439 int rtval; 440 struct vnode *vp; 441 442 vp = object->handle; 443 rtval = VOP_GETPAGES(vp, mpp, PAGE_SIZE, 0, 0, seqaccess); 444 if (rtval == EOPNOTSUPP) 445 panic("vnode_pager: vfs's must implement vop_getpages"); 446 return rtval; 447 } 448 449 /* 450 * This is now called from local media FS's to operate against their 451 * own vnodes if they fail to implement VOP_GETPAGES. 452 * 453 * With all the caching local media devices do these days there is really 454 * very little point to attempting to restrict the I/O size to contiguous 455 * blocks on-disk, especially if our caller thinks we need all the specified 456 * pages. Just construct and issue a READ. 457 */ 458 int 459 vnode_pager_generic_getpages(struct vnode *vp, vm_page_t *mpp, int bytecount, 460 int reqpage, int seqaccess) 461 { 462 struct iovec aiov; 463 struct uio auio; 464 off_t foff; 465 int error; 466 int count; 467 int i; 468 int ioflags; 469 int obytecount; 470 471 /* 472 * Do not do anything if the vnode is bad. 473 */ 474 if (vp->v_mount == NULL) 475 return VM_PAGER_BAD; 476 477 /* 478 * Calculate the number of pages. Since we are paging in whole 479 * pages, adjust bytecount to be an integral multiple of the page 480 * size. It will be clipped to the file EOF later on. 481 */ 482 bytecount = round_page(bytecount); 483 count = bytecount / PAGE_SIZE; 484 485 /* 486 * We could check m[reqpage]->valid here and shortcut the operation, 487 * but doing so breaks read-ahead. Instead assume that the VM 488 * system has already done at least the check, don't worry about 489 * any races, and issue the VOP_READ to allow read-ahead to function. 490 * 491 * This keeps the pipeline full for I/O bound sequentially scanned 492 * mmap()'s 493 */ 494 /* don't shortcut */ 495 496 /* 497 * Discard pages past the file EOF. If the requested page is past 498 * the file EOF we just leave its valid bits set to 0, the caller 499 * expects to maintain ownership of the requested page. If the 500 * entire range is past file EOF discard everything and generate 501 * a pagein error. 502 */ 503 foff = IDX_TO_OFF(mpp[0]->pindex); 504 if (foff >= vp->v_filesize) { 505 for (i = 0; i < count; i++) { 506 if (i != reqpage) 507 vnode_pager_freepage(mpp[i]); 508 } 509 return VM_PAGER_ERROR; 510 } 511 512 if (foff + bytecount > vp->v_filesize) { 513 bytecount = vp->v_filesize - foff; 514 i = round_page(bytecount) / PAGE_SIZE; 515 while (count > i) { 516 --count; 517 if (count != reqpage) 518 vnode_pager_freepage(mpp[count]); 519 } 520 } 521 522 /* 523 * The size of the transfer is bytecount. bytecount will be an 524 * integral multiple of the page size unless it has been clipped 525 * to the file EOF. The transfer cannot exceed the file EOF. 526 * 527 * When dealing with real devices we must round-up to the device 528 * sector size. 529 */ 530 if (vp->v_type == VBLK || vp->v_type == VCHR) { 531 int secmask = vp->v_rdev->si_bsize_phys - 1; 532 KASSERT(secmask < PAGE_SIZE, ("vnode_pager_generic_getpages: sector size %d too large", secmask + 1)); 533 bytecount = (bytecount + secmask) & ~secmask; 534 } 535 obytecount = bytecount; 536 537 /* 538 * Severe hack to avoid deadlocks with the buffer cache 539 */ 540 for (i = 0; i < count; ++i) { 541 vm_page_t mt = mpp[i]; 542 543 vm_page_io_start(mt); 544 vm_page_wakeup(mt); 545 } 546 547 /* 548 * Issue the I/O with some read-ahead if bytecount > PAGE_SIZE 549 */ 550 ioflags = IO_VMIO; 551 if (seqaccess) 552 ioflags |= IO_SEQMAX << IO_SEQSHIFT; 553 554 aiov.iov_base = NULL; 555 aiov.iov_len = bytecount; 556 auio.uio_iov = &aiov; 557 auio.uio_iovcnt = 1; 558 auio.uio_offset = foff; 559 auio.uio_segflg = UIO_NOCOPY; 560 auio.uio_rw = UIO_READ; 561 auio.uio_resid = bytecount; 562 auio.uio_td = NULL; 563 mycpu->gd_cnt.v_vnodein++; 564 mycpu->gd_cnt.v_vnodepgsin += count; 565 566 error = VOP_READ(vp, &auio, ioflags, proc0.p_ucred); 567 568 /* 569 * Severe hack to avoid deadlocks with the buffer cache 570 */ 571 for (i = 0; i < count; ++i) { 572 vm_page_busy_wait(mpp[i], FALSE, "getpgs"); 573 vm_page_io_finish(mpp[i]); 574 } 575 576 /* 577 * Calculate the actual number of bytes read and clean up the 578 * page list. 579 */ 580 bytecount -= auio.uio_resid; 581 582 for (i = 0; i < count; ++i) { 583 vm_page_t mt = mpp[i]; 584 585 if (i != reqpage) { 586 if (error == 0 && mt->valid) { 587 if (mt->flags & PG_REFERENCED) 588 vm_page_activate(mt); 589 else 590 vm_page_deactivate(mt); 591 vm_page_wakeup(mt); 592 } else { 593 vnode_pager_freepage(mt); 594 } 595 } else if (mt->valid == 0) { 596 if (error == 0) { 597 kprintf("page failed but no I/O error page " 598 "%p object %p pindex %d\n", 599 mt, mt->object, (int) mt->pindex); 600 kprintf("i=%d foff=%016lx bytecount=%d/%d " 601 "uioresid=%zd\n", 602 i, foff, obytecount, bytecount, 603 auio.uio_resid); 604 /* whoops, something happened */ 605 error = EINVAL; 606 } 607 } else if (mt->valid != VM_PAGE_BITS_ALL) { 608 /* 609 * Zero-extend the requested page if necessary (if 610 * the filesystem is using a small block size). 611 */ 612 vm_page_zero_invalid(mt, TRUE); 613 } 614 } 615 if (error) { 616 kprintf("vnode_pager_getpage: I/O read error\n"); 617 } 618 return (error ? VM_PAGER_ERROR : VM_PAGER_OK); 619 } 620 621 /* 622 * EOPNOTSUPP is no longer legal. For local media VFS's that do not 623 * implement their own VOP_PUTPAGES, their VOP_PUTPAGES should call to 624 * vnode_pager_generic_putpages() to implement the previous behaviour. 625 * 626 * Caller has already cleared the pmap modified bits, if any. 627 * 628 * All other FS's should use the bypass to get to the local media 629 * backing vp's VOP_PUTPAGES. 630 */ 631 static void 632 vnode_pager_putpages(vm_object_t object, vm_page_t *m, int count, 633 int sync, int *rtvals) 634 { 635 int rtval; 636 struct vnode *vp; 637 int bytes = count * PAGE_SIZE; 638 639 /* 640 * Force synchronous operation if we are extremely low on memory 641 * to prevent a low-memory deadlock. VOP operations often need to 642 * allocate more memory to initiate the I/O ( i.e. do a BMAP 643 * operation ). The swapper handles the case by limiting the amount 644 * of asynchronous I/O, but that sort of solution doesn't scale well 645 * for the vnode pager without a lot of work. 646 * 647 * Also, the backing vnode's iodone routine may not wake the pageout 648 * daemon up. This should be probably be addressed XXX. 649 */ 650 651 if ((vmstats.v_free_count + vmstats.v_cache_count) < 652 vmstats.v_pageout_free_min) { 653 sync |= OBJPC_SYNC; 654 } 655 656 /* 657 * Call device-specific putpages function 658 */ 659 vp = object->handle; 660 rtval = VOP_PUTPAGES(vp, m, bytes, sync, rtvals, 0); 661 if (rtval == EOPNOTSUPP) { 662 kprintf("vnode_pager: *** WARNING *** stale FS putpages\n"); 663 rtval = vnode_pager_generic_putpages( vp, m, bytes, sync, rtvals); 664 } 665 } 666 667 668 /* 669 * This is now called from local media FS's to operate against their 670 * own vnodes if they fail to implement VOP_PUTPAGES. 671 * 672 * This is typically called indirectly via the pageout daemon and 673 * clustering has already typically occured, so in general we ask the 674 * underlying filesystem to write the data out asynchronously rather 675 * then delayed. 676 */ 677 int 678 vnode_pager_generic_putpages(struct vnode *vp, vm_page_t *m, int bytecount, 679 int flags, int *rtvals) 680 { 681 int i; 682 int maxsize, ncount, count; 683 vm_ooffset_t poffset; 684 struct uio auio; 685 struct iovec aiov; 686 int error; 687 int ioflags; 688 689 count = bytecount / PAGE_SIZE; 690 691 for (i = 0; i < count; i++) 692 rtvals[i] = VM_PAGER_AGAIN; 693 694 if ((int) m[0]->pindex < 0) { 695 kprintf("vnode_pager_putpages: attempt to write meta-data!!! -- 0x%lx(%x)\n", 696 (long)m[0]->pindex, m[0]->dirty); 697 rtvals[0] = VM_PAGER_BAD; 698 return VM_PAGER_BAD; 699 } 700 701 maxsize = count * PAGE_SIZE; 702 ncount = count; 703 704 poffset = IDX_TO_OFF(m[0]->pindex); 705 706 /* 707 * If the page-aligned write is larger then the actual file we 708 * have to invalidate pages occuring beyond the file EOF. 709 * 710 * If the file EOF resides in the middle of a page we still clear 711 * all of that page's dirty bits later on. If we didn't it would 712 * endlessly re-write. 713 * 714 * We do not under any circumstances truncate the valid bits, as 715 * this will screw up bogus page replacement. 716 * 717 * The caller has already read-protected the pages. The VFS must 718 * use the buffer cache to wrap the pages. The pages might not 719 * be immediately flushed by the buffer cache but once under its 720 * control the pages themselves can wind up being marked clean 721 * and their covering buffer cache buffer can be marked dirty. 722 */ 723 if (poffset + maxsize > vp->v_filesize) { 724 if (poffset < vp->v_filesize) { 725 maxsize = vp->v_filesize - poffset; 726 ncount = btoc(maxsize); 727 } else { 728 maxsize = 0; 729 ncount = 0; 730 } 731 if (ncount < count) { 732 for (i = ncount; i < count; i++) { 733 rtvals[i] = VM_PAGER_BAD; 734 } 735 } 736 } 737 738 /* 739 * pageouts are already clustered, use IO_ASYNC to force a bawrite() 740 * rather then a bdwrite() to prevent paging I/O from saturating 741 * the buffer cache. Dummy-up the sequential heuristic to cause 742 * large ranges to cluster. If neither IO_SYNC or IO_ASYNC is set, 743 * the system decides how to cluster. 744 */ 745 ioflags = IO_VMIO; 746 if (flags & (VM_PAGER_PUT_SYNC | VM_PAGER_PUT_INVAL)) 747 ioflags |= IO_SYNC; 748 else if ((flags & VM_PAGER_CLUSTER_OK) == 0) 749 ioflags |= IO_ASYNC; 750 ioflags |= (flags & VM_PAGER_PUT_INVAL) ? IO_INVAL: 0; 751 ioflags |= IO_SEQMAX << IO_SEQSHIFT; 752 753 aiov.iov_base = (caddr_t) 0; 754 aiov.iov_len = maxsize; 755 auio.uio_iov = &aiov; 756 auio.uio_iovcnt = 1; 757 auio.uio_offset = poffset; 758 auio.uio_segflg = UIO_NOCOPY; 759 auio.uio_rw = UIO_WRITE; 760 auio.uio_resid = maxsize; 761 auio.uio_td = NULL; 762 error = VOP_WRITE(vp, &auio, ioflags, proc0.p_ucred); 763 mycpu->gd_cnt.v_vnodeout++; 764 mycpu->gd_cnt.v_vnodepgsout += ncount; 765 766 if (error) { 767 krateprintf(&vbadrate, 768 "vnode_pager_putpages: I/O error %d\n", error); 769 } 770 if (auio.uio_resid) { 771 krateprintf(&vresrate, 772 "vnode_pager_putpages: residual I/O %zd at %lu\n", 773 auio.uio_resid, (u_long)m[0]->pindex); 774 } 775 if (error == 0) { 776 for (i = 0; i < ncount; i++) { 777 rtvals[i] = VM_PAGER_OK; 778 vm_page_undirty(m[i]); 779 } 780 } 781 return rtvals[0]; 782 } 783 784 /* 785 * Run the chain and if the bottom-most object is a vnode-type lock the 786 * underlying vnode. A locked vnode or NULL is returned. 787 * 788 * Caller must hold the first object. 789 */ 790 struct vnode * 791 vnode_pager_lock(vm_map_backing_t ba) 792 { 793 vm_map_backing_t lba; 794 struct vnode *vp; 795 vm_object_t lobject; 796 int error; 797 798 if (ba == NULL) 799 return NULL; 800 lba = ba; 801 while (lba->backing_ba) 802 lba = lba->backing_ba; 803 if ((lobject = lba->object) == NULL) 804 return NULL; 805 if (lba != ba) 806 vm_object_hold_shared(lobject); 807 808 while (lobject->type == OBJT_VNODE && 809 (lobject->flags & OBJ_DEAD) == 0) { 810 /* 811 * Extract the vp 812 */ 813 vp = lobject->handle; 814 error = vget(vp, LK_SHARED | LK_RETRY | LK_CANRECURSE); 815 if (error == 0) { 816 if (lobject->handle == vp) 817 break; 818 vput(vp); 819 } else { 820 kprintf("vnode_pager_lock: vp %p error %d " 821 "lockstatus %d, retrying\n", 822 vp, error, 823 lockstatus(&vp->v_lock, curthread)); 824 tsleep(lobject->handle, 0, "vnpgrl", hz); 825 } 826 vp = NULL; 827 } 828 if (lba != ba) 829 vm_object_drop(lobject); 830 return (vp); 831 } 832