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sys/vm/vm_fault.c
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1 /*- 2 * Copyright (c) 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * Copyright (c) 1994 John S. Dyson 5 * All rights reserved. 6 * Copyright (c) 1994 David Greenman 7 * All rights reserved. 8 * 9 * 10 * This code is derived from software contributed to Berkeley by 11 * The Mach Operating System project at Carnegie-Mellon University. 12 * 13 * Redistribution and use in source and binary forms, with or without 14 * modification, are permitted provided that the following conditions 15 * are met: 16 * 1. Redistributions of source code must retain the above copyright 17 * notice, this list of conditions and the following disclaimer. 18 * 2. Redistributions in binary form must reproduce the above copyright 19 * notice, this list of conditions and the following disclaimer in the 20 * documentation and/or other materials provided with the distribution. 21 * 3. All advertising materials mentioning features or use of this software 22 * must display the following acknowledgement: 23 * This product includes software developed by the University of 24 * California, Berkeley and its contributors. 25 * 4. Neither the name of the University nor the names of its contributors 26 * may be used to endorse or promote products derived from this software 27 * without specific prior written permission. 28 * 29 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 30 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 31 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 32 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 33 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 34 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 35 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 36 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 37 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 38 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 39 * SUCH DAMAGE. 40 * 41 * from: @(#)vm_fault.c 8.4 (Berkeley) 1/12/94 42 * 43 * 44 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 45 * All rights reserved. 46 * 47 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 48 * 49 * Permission to use, copy, modify and distribute this software and 50 * its documentation is hereby granted, provided that both the copyright 51 * notice and this permission notice appear in all copies of the 52 * software, derivative works or modified versions, and any portions 53 * thereof, and that both notices appear in supporting documentation. 54 * 55 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 56 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 57 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 58 * 59 * Carnegie Mellon requests users of this software to return to 60 * 61 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 62 * School of Computer Science 63 * Carnegie Mellon University 64 * Pittsburgh PA 15213-3890 65 * 66 * any improvements or extensions that they make and grant Carnegie the 67 * rights to redistribute these changes. 68 */ 69 70 /* 71 * Page fault handling module. 72 */ 73 74 #include <sys/cdefs.h> 75 __FBSDID("$FreeBSD: releng/8.3/sys/vm/vm_fault.c 219066 2011-02-26 21:27:41Z alc $"); 76 77 #include "opt_vm.h" 78 79 #include <sys/param.h> 80 #include <sys/systm.h> 81 #include <sys/kernel.h> 82 #include <sys/lock.h> 83 #include <sys/mutex.h> 84 #include <sys/proc.h> 85 #include <sys/resourcevar.h> 86 #include <sys/sysctl.h> 87 #include <sys/vmmeter.h> 88 #include <sys/vnode.h> 89 90 #include <vm/vm.h> 91 #include <vm/vm_param.h> 92 #include <vm/pmap.h> 93 #include <vm/vm_map.h> 94 #include <vm/vm_object.h> 95 #include <vm/vm_page.h> 96 #include <vm/vm_pageout.h> 97 #include <vm/vm_kern.h> 98 #include <vm/vm_pager.h> 99 #include <vm/vnode_pager.h> 100 #include <vm/vm_extern.h> 101 102 #include <sys/mount.h> /* XXX Temporary for VFS_LOCK_GIANT() */ 103 104 #define PFBAK 4 105 #define PFFOR 4 106 #define PAGEORDER_SIZE (PFBAK+PFFOR) 107 108 static int prefault_pageorder[] = { 109 -1 * PAGE_SIZE, 1 * PAGE_SIZE, 110 -2 * PAGE_SIZE, 2 * PAGE_SIZE, 111 -3 * PAGE_SIZE, 3 * PAGE_SIZE, 112 -4 * PAGE_SIZE, 4 * PAGE_SIZE 113 }; 114 115 static int vm_fault_additional_pages(vm_page_t, int, int, vm_page_t *, int *); 116 static void vm_fault_prefault(pmap_t, vm_offset_t, vm_map_entry_t); 117 118 #define VM_FAULT_READ_AHEAD 8 119 #define VM_FAULT_READ_BEHIND 7 120 #define VM_FAULT_READ (VM_FAULT_READ_AHEAD+VM_FAULT_READ_BEHIND+1) 121 122 struct faultstate { 123 vm_page_t m; 124 vm_object_t object; 125 vm_pindex_t pindex; 126 vm_page_t first_m; 127 vm_object_t first_object; 128 vm_pindex_t first_pindex; 129 vm_map_t map; 130 vm_map_entry_t entry; 131 int lookup_still_valid; 132 struct vnode *vp; 133 int vfslocked; 134 }; 135 136 static inline void 137 release_page(struct faultstate *fs) 138 { 139 140 vm_page_wakeup(fs->m); 141 vm_page_lock_queues(); 142 vm_page_deactivate(fs->m); 143 vm_page_unlock_queues(); 144 fs->m = NULL; 145 } 146 147 static inline void 148 unlock_map(struct faultstate *fs) 149 { 150 151 if (fs->lookup_still_valid) { 152 vm_map_lookup_done(fs->map, fs->entry); 153 fs->lookup_still_valid = FALSE; 154 } 155 } 156 157 static void 158 unlock_and_deallocate(struct faultstate *fs) 159 { 160 161 vm_object_pip_wakeup(fs->object); 162 VM_OBJECT_UNLOCK(fs->object); 163 if (fs->object != fs->first_object) { 164 VM_OBJECT_LOCK(fs->first_object); 165 vm_page_lock_queues(); 166 vm_page_free(fs->first_m); 167 vm_page_unlock_queues(); 168 vm_object_pip_wakeup(fs->first_object); 169 VM_OBJECT_UNLOCK(fs->first_object); 170 fs->first_m = NULL; 171 } 172 vm_object_deallocate(fs->first_object); 173 unlock_map(fs); 174 if (fs->vp != NULL) { 175 vput(fs->vp); 176 fs->vp = NULL; 177 } 178 VFS_UNLOCK_GIANT(fs->vfslocked); 179 fs->vfslocked = 0; 180 } 181 182 /* 183 * TRYPAGER - used by vm_fault to calculate whether the pager for the 184 * current object *might* contain the page. 185 * 186 * default objects are zero-fill, there is no real pager. 187 */ 188 #define TRYPAGER (fs.object->type != OBJT_DEFAULT && \ 189 (((fault_flags & VM_FAULT_WIRE_MASK) == 0) || wired)) 190 191 /* 192 * vm_fault: 193 * 194 * Handle a page fault occurring at the given address, 195 * requiring the given permissions, in the map specified. 196 * If successful, the page is inserted into the 197 * associated physical map. 198 * 199 * NOTE: the given address should be truncated to the 200 * proper page address. 201 * 202 * KERN_SUCCESS is returned if the page fault is handled; otherwise, 203 * a standard error specifying why the fault is fatal is returned. 204 * 205 * 206 * The map in question must be referenced, and remains so. 207 * Caller may hold no locks. 208 */ 209 int 210 vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type, 211 int fault_flags) 212 { 213 vm_prot_t prot; 214 int is_first_object_locked, result; 215 boolean_t are_queues_locked, growstack, wired; 216 int map_generation; 217 vm_object_t next_object; 218 vm_page_t marray[VM_FAULT_READ], mt, mt_prev; 219 int hardfault; 220 int faultcount, ahead, behind, alloc_req; 221 struct faultstate fs; 222 struct vnode *vp; 223 int locked, error; 224 225 hardfault = 0; 226 growstack = TRUE; 227 PCPU_INC(cnt.v_vm_faults); 228 fs.vp = NULL; 229 fs.vfslocked = 0; 230 faultcount = behind = 0; 231 232 RetryFault:; 233 234 /* 235 * Find the backing store object and offset into it to begin the 236 * search. 237 */ 238 fs.map = map; 239 result = vm_map_lookup(&fs.map, vaddr, fault_type, &fs.entry, 240 &fs.first_object, &fs.first_pindex, &prot, &wired); 241 if (result != KERN_SUCCESS) { 242 if (result != KERN_PROTECTION_FAILURE || 243 (fault_flags & VM_FAULT_WIRE_MASK) != VM_FAULT_USER_WIRE) { 244 if (growstack && result == KERN_INVALID_ADDRESS && 245 map != kernel_map && curproc != NULL) { 246 result = vm_map_growstack(curproc, vaddr); 247 if (result != KERN_SUCCESS) 248 return (KERN_FAILURE); 249 growstack = FALSE; 250 goto RetryFault; 251 } 252 return (result); 253 } 254 255 /* 256 * If we are user-wiring a r/w segment, and it is COW, then 257 * we need to do the COW operation. Note that we don't COW 258 * currently RO sections now, because it is NOT desirable 259 * to COW .text. We simply keep .text from ever being COW'ed 260 * and take the heat that one cannot debug wired .text sections. 261 */ 262 result = vm_map_lookup(&fs.map, vaddr, 263 VM_PROT_READ|VM_PROT_WRITE|VM_PROT_OVERRIDE_WRITE, 264 &fs.entry, &fs.first_object, &fs.first_pindex, &prot, &wired); 265 if (result != KERN_SUCCESS) 266 return (result); 267 268 /* 269 * If we don't COW now, on a user wire, the user will never 270 * be able to write to the mapping. If we don't make this 271 * restriction, the bookkeeping would be nearly impossible. 272 * 273 * XXX The following assignment modifies the map without 274 * holding a write lock on it. 275 */ 276 if ((fs.entry->protection & VM_PROT_WRITE) == 0) 277 fs.entry->max_protection &= ~VM_PROT_WRITE; 278 } 279 280 map_generation = fs.map->timestamp; 281 282 if (fs.entry->eflags & MAP_ENTRY_NOFAULT) { 283 panic("vm_fault: fault on nofault entry, addr: %lx", 284 (u_long)vaddr); 285 } 286 287 /* 288 * Make a reference to this object to prevent its disposal while we 289 * are messing with it. Once we have the reference, the map is free 290 * to be diddled. Since objects reference their shadows (and copies), 291 * they will stay around as well. 292 * 293 * Bump the paging-in-progress count to prevent size changes (e.g. 294 * truncation operations) during I/O. This must be done after 295 * obtaining the vnode lock in order to avoid possible deadlocks. 296 */ 297 VM_OBJECT_LOCK(fs.first_object); 298 vm_object_reference_locked(fs.first_object); 299 vm_object_pip_add(fs.first_object, 1); 300 301 fs.lookup_still_valid = TRUE; 302 303 if (wired) 304 fault_type = prot; 305 306 fs.first_m = NULL; 307 308 /* 309 * Search for the page at object/offset. 310 */ 311 fs.object = fs.first_object; 312 fs.pindex = fs.first_pindex; 313 while (TRUE) { 314 /* 315 * If the object is dead, we stop here 316 */ 317 if (fs.object->flags & OBJ_DEAD) { 318 unlock_and_deallocate(&fs); 319 return (KERN_PROTECTION_FAILURE); 320 } 321 322 /* 323 * See if page is resident 324 */ 325 fs.m = vm_page_lookup(fs.object, fs.pindex); 326 if (fs.m != NULL) { 327 /* 328 * check for page-based copy on write. 329 * We check fs.object == fs.first_object so 330 * as to ensure the legacy COW mechanism is 331 * used when the page in question is part of 332 * a shadow object. Otherwise, vm_page_cowfault() 333 * removes the page from the backing object, 334 * which is not what we want. 335 */ 336 vm_page_lock_queues(); 337 if ((fs.m->cow) && 338 (fault_type & VM_PROT_WRITE) && 339 (fs.object == fs.first_object)) { 340 vm_page_cowfault(fs.m); 341 vm_page_unlock_queues(); 342 unlock_and_deallocate(&fs); 343 goto RetryFault; 344 } 345 346 /* 347 * Wait/Retry if the page is busy. We have to do this 348 * if the page is busy via either VPO_BUSY or 349 * vm_page_t->busy because the vm_pager may be using 350 * vm_page_t->busy for pageouts ( and even pageins if 351 * it is the vnode pager ), and we could end up trying 352 * to pagein and pageout the same page simultaneously. 353 * 354 * We can theoretically allow the busy case on a read 355 * fault if the page is marked valid, but since such 356 * pages are typically already pmap'd, putting that 357 * special case in might be more effort then it is 358 * worth. We cannot under any circumstances mess 359 * around with a vm_page_t->busy page except, perhaps, 360 * to pmap it. 361 */ 362 if ((fs.m->oflags & VPO_BUSY) || fs.m->busy) { 363 vm_page_unlock_queues(); 364 if (fs.object != fs.first_object) { 365 if (!VM_OBJECT_TRYLOCK( 366 fs.first_object)) { 367 VM_OBJECT_UNLOCK(fs.object); 368 VM_OBJECT_LOCK(fs.first_object); 369 VM_OBJECT_LOCK(fs.object); 370 } 371 vm_page_lock_queues(); 372 vm_page_free(fs.first_m); 373 vm_page_unlock_queues(); 374 vm_object_pip_wakeup(fs.first_object); 375 VM_OBJECT_UNLOCK(fs.first_object); 376 fs.first_m = NULL; 377 } 378 unlock_map(&fs); 379 if (fs.m == vm_page_lookup(fs.object, 380 fs.pindex)) { 381 vm_page_sleep_if_busy(fs.m, TRUE, 382 "vmpfw"); 383 } 384 vm_object_pip_wakeup(fs.object); 385 VM_OBJECT_UNLOCK(fs.object); 386 PCPU_INC(cnt.v_intrans); 387 vm_object_deallocate(fs.first_object); 388 goto RetryFault; 389 } 390 vm_pageq_remove(fs.m); 391 vm_page_unlock_queues(); 392 393 /* 394 * Mark page busy for other processes, and the 395 * pagedaemon. If it still isn't completely valid 396 * (readable), jump to readrest, else break-out ( we 397 * found the page ). 398 */ 399 vm_page_busy(fs.m); 400 if (fs.m->valid != VM_PAGE_BITS_ALL) 401 goto readrest; 402 break; 403 } 404 405 /* 406 * Page is not resident, If this is the search termination 407 * or the pager might contain the page, allocate a new page. 408 */ 409 if (TRYPAGER || fs.object == fs.first_object) { 410 if (fs.pindex >= fs.object->size) { 411 unlock_and_deallocate(&fs); 412 return (KERN_PROTECTION_FAILURE); 413 } 414 415 /* 416 * Allocate a new page for this object/offset pair. 417 * 418 * Unlocked read of the p_flag is harmless. At 419 * worst, the P_KILLED might be not observed 420 * there, and allocation can fail, causing 421 * restart and new reading of the p_flag. 422 */ 423 fs.m = NULL; 424 if (!vm_page_count_severe() || P_KILLED(curproc)) { 425 #if VM_NRESERVLEVEL > 0 426 if ((fs.object->flags & OBJ_COLORED) == 0) { 427 fs.object->flags |= OBJ_COLORED; 428 fs.object->pg_color = atop(vaddr) - 429 fs.pindex; 430 } 431 #endif 432 alloc_req = P_KILLED(curproc) ? 433 VM_ALLOC_SYSTEM : VM_ALLOC_NORMAL; 434 if (fs.object->type != OBJT_VNODE && 435 fs.object->backing_object == NULL) 436 alloc_req |= VM_ALLOC_ZERO; 437 fs.m = vm_page_alloc(fs.object, fs.pindex, 438 alloc_req); 439 } 440 if (fs.m == NULL) { 441 unlock_and_deallocate(&fs); 442 VM_WAITPFAULT; 443 goto RetryFault; 444 } else if (fs.m->valid == VM_PAGE_BITS_ALL) 445 break; 446 } 447 448 readrest: 449 /* 450 * We have found a valid page or we have allocated a new page. 451 * The page thus may not be valid or may not be entirely 452 * valid. 453 * 454 * Attempt to fault-in the page if there is a chance that the 455 * pager has it, and potentially fault in additional pages 456 * at the same time. 457 */ 458 if (TRYPAGER) { 459 int rv; 460 int reqpage = 0; 461 u_char behavior = vm_map_entry_behavior(fs.entry); 462 463 if (behavior == MAP_ENTRY_BEHAV_RANDOM || 464 P_KILLED(curproc)) { 465 ahead = 0; 466 behind = 0; 467 } else { 468 behind = (vaddr - fs.entry->start) >> PAGE_SHIFT; 469 if (behind > VM_FAULT_READ_BEHIND) 470 behind = VM_FAULT_READ_BEHIND; 471 472 ahead = ((fs.entry->end - vaddr) >> PAGE_SHIFT) - 1; 473 if (ahead > VM_FAULT_READ_AHEAD) 474 ahead = VM_FAULT_READ_AHEAD; 475 } 476 is_first_object_locked = FALSE; 477 if ((behavior == MAP_ENTRY_BEHAV_SEQUENTIAL || 478 (behavior != MAP_ENTRY_BEHAV_RANDOM && 479 fs.pindex >= fs.entry->lastr && 480 fs.pindex < fs.entry->lastr + VM_FAULT_READ)) && 481 (fs.first_object == fs.object || 482 (is_first_object_locked = VM_OBJECT_TRYLOCK(fs.first_object))) && 483 fs.first_object->type != OBJT_DEVICE && 484 fs.first_object->type != OBJT_PHYS && 485 fs.first_object->type != OBJT_SG) { 486 vm_pindex_t firstpindex; 487 488 if (fs.first_pindex < 2 * VM_FAULT_READ) 489 firstpindex = 0; 490 else 491 firstpindex = fs.first_pindex - 2 * VM_FAULT_READ; 492 mt = fs.first_object != fs.object ? 493 fs.first_m : fs.m; 494 KASSERT(mt != NULL, ("vm_fault: missing mt")); 495 KASSERT((mt->oflags & VPO_BUSY) != 0, 496 ("vm_fault: mt %p not busy", mt)); 497 mt_prev = vm_page_prev(mt); 498 499 are_queues_locked = FALSE; 500 /* 501 * note: partially valid pages cannot be 502 * included in the lookahead - NFS piecemeal 503 * writes will barf on it badly. 504 */ 505 while ((mt = mt_prev) != NULL && 506 mt->pindex >= firstpindex && 507 mt->valid == VM_PAGE_BITS_ALL) { 508 mt_prev = vm_page_prev(mt); 509 if (mt->busy || 510 (mt->oflags & VPO_BUSY)) 511 continue; 512 if (!are_queues_locked) { 513 are_queues_locked = TRUE; 514 vm_page_lock_queues(); 515 } 516 if (mt->hold_count || 517 mt->wire_count) 518 continue; 519 pmap_remove_all(mt); 520 if (mt->dirty) { 521 vm_page_deactivate(mt); 522 } else { 523 vm_page_cache(mt); 524 } 525 } 526 if (are_queues_locked) 527 vm_page_unlock_queues(); 528 ahead += behind; 529 behind = 0; 530 } 531 if (is_first_object_locked) 532 VM_OBJECT_UNLOCK(fs.first_object); 533 534 /* 535 * Call the pager to retrieve the data, if any, after 536 * releasing the lock on the map. We hold a ref on 537 * fs.object and the pages are VPO_BUSY'd. 538 */ 539 unlock_map(&fs); 540 541 vnode_lock: 542 if (fs.object->type == OBJT_VNODE) { 543 vp = fs.object->handle; 544 if (vp == fs.vp) 545 goto vnode_locked; 546 else if (fs.vp != NULL) { 547 vput(fs.vp); 548 fs.vp = NULL; 549 } 550 locked = VOP_ISLOCKED(vp); 551 552 if (VFS_NEEDSGIANT(vp->v_mount) && !fs.vfslocked) { 553 fs.vfslocked = 1; 554 if (!mtx_trylock(&Giant)) { 555 VM_OBJECT_UNLOCK(fs.object); 556 mtx_lock(&Giant); 557 VM_OBJECT_LOCK(fs.object); 558 goto vnode_lock; 559 } 560 } 561 if (locked != LK_EXCLUSIVE) 562 locked = LK_SHARED; 563 /* Do not sleep for vnode lock while fs.m is busy */ 564 error = vget(vp, locked | LK_CANRECURSE | 565 LK_NOWAIT, curthread); 566 if (error != 0) { 567 int vfslocked; 568 569 vfslocked = fs.vfslocked; 570 fs.vfslocked = 0; /* Keep Giant */ 571 vhold(vp); 572 release_page(&fs); 573 unlock_and_deallocate(&fs); 574 error = vget(vp, locked | LK_RETRY | 575 LK_CANRECURSE, curthread); 576 vdrop(vp); 577 fs.vp = vp; 578 fs.vfslocked = vfslocked; 579 KASSERT(error == 0, 580 ("vm_fault: vget failed")); 581 goto RetryFault; 582 } 583 fs.vp = vp; 584 } 585 vnode_locked: 586 KASSERT(fs.vp == NULL || !fs.map->system_map, 587 ("vm_fault: vnode-backed object mapped by system map")); 588 589 /* 590 * now we find out if any other pages should be paged 591 * in at this time this routine checks to see if the 592 * pages surrounding this fault reside in the same 593 * object as the page for this fault. If they do, 594 * then they are faulted in also into the object. The 595 * array "marray" returned contains an array of 596 * vm_page_t structs where one of them is the 597 * vm_page_t passed to the routine. The reqpage 598 * return value is the index into the marray for the 599 * vm_page_t passed to the routine. 600 * 601 * fs.m plus the additional pages are VPO_BUSY'd. 602 */ 603 faultcount = vm_fault_additional_pages( 604 fs.m, behind, ahead, marray, &reqpage); 605 606 rv = faultcount ? 607 vm_pager_get_pages(fs.object, marray, faultcount, 608 reqpage) : VM_PAGER_FAIL; 609 610 if (rv == VM_PAGER_OK) { 611 /* 612 * Found the page. Leave it busy while we play 613 * with it. 614 */ 615 616 /* 617 * Relookup in case pager changed page. Pager 618 * is responsible for disposition of old page 619 * if moved. 620 */ 621 fs.m = vm_page_lookup(fs.object, fs.pindex); 622 if (!fs.m) { 623 unlock_and_deallocate(&fs); 624 goto RetryFault; 625 } 626 627 hardfault++; 628 break; /* break to PAGE HAS BEEN FOUND */ 629 } 630 /* 631 * Remove the bogus page (which does not exist at this 632 * object/offset); before doing so, we must get back 633 * our object lock to preserve our invariant. 634 * 635 * Also wake up any other process that may want to bring 636 * in this page. 637 * 638 * If this is the top-level object, we must leave the 639 * busy page to prevent another process from rushing 640 * past us, and inserting the page in that object at 641 * the same time that we are. 642 */ 643 if (rv == VM_PAGER_ERROR) 644 printf("vm_fault: pager read error, pid %d (%s)\n", 645 curproc->p_pid, curproc->p_comm); 646 /* 647 * Data outside the range of the pager or an I/O error 648 */ 649 /* 650 * XXX - the check for kernel_map is a kludge to work 651 * around having the machine panic on a kernel space 652 * fault w/ I/O error. 653 */ 654 if (((fs.map != kernel_map) && (rv == VM_PAGER_ERROR)) || 655 (rv == VM_PAGER_BAD)) { 656 vm_page_lock_queues(); 657 vm_page_free(fs.m); 658 vm_page_unlock_queues(); 659 fs.m = NULL; 660 unlock_and_deallocate(&fs); 661 return ((rv == VM_PAGER_ERROR) ? KERN_FAILURE : KERN_PROTECTION_FAILURE); 662 } 663 if (fs.object != fs.first_object) { 664 vm_page_lock_queues(); 665 vm_page_free(fs.m); 666 vm_page_unlock_queues(); 667 fs.m = NULL; 668 /* 669 * XXX - we cannot just fall out at this 670 * point, m has been freed and is invalid! 671 */ 672 } 673 } 674 675 /* 676 * We get here if the object has default pager (or unwiring) 677 * or the pager doesn't have the page. 678 */ 679 if (fs.object == fs.first_object) 680 fs.first_m = fs.m; 681 682 /* 683 * Move on to the next object. Lock the next object before 684 * unlocking the current one. 685 */ 686 fs.pindex += OFF_TO_IDX(fs.object->backing_object_offset); 687 next_object = fs.object->backing_object; 688 if (next_object == NULL) { 689 /* 690 * If there's no object left, fill the page in the top 691 * object with zeros. 692 */ 693 if (fs.object != fs.first_object) { 694 vm_object_pip_wakeup(fs.object); 695 VM_OBJECT_UNLOCK(fs.object); 696 697 fs.object = fs.first_object; 698 fs.pindex = fs.first_pindex; 699 fs.m = fs.first_m; 700 VM_OBJECT_LOCK(fs.object); 701 } 702 fs.first_m = NULL; 703 704 /* 705 * Zero the page if necessary and mark it valid. 706 */ 707 if ((fs.m->flags & PG_ZERO) == 0) { 708 pmap_zero_page(fs.m); 709 } else { 710 PCPU_INC(cnt.v_ozfod); 711 } 712 PCPU_INC(cnt.v_zfod); 713 fs.m->valid = VM_PAGE_BITS_ALL; 714 break; /* break to PAGE HAS BEEN FOUND */ 715 } else { 716 KASSERT(fs.object != next_object, 717 ("object loop %p", next_object)); 718 VM_OBJECT_LOCK(next_object); 719 vm_object_pip_add(next_object, 1); 720 if (fs.object != fs.first_object) 721 vm_object_pip_wakeup(fs.object); 722 VM_OBJECT_UNLOCK(fs.object); 723 fs.object = next_object; 724 } 725 } 726 727 KASSERT((fs.m->oflags & VPO_BUSY) != 0, 728 ("vm_fault: not busy after main loop")); 729 730 /* 731 * PAGE HAS BEEN FOUND. [Loop invariant still holds -- the object lock 732 * is held.] 733 */ 734 735 /* 736 * If the page is being written, but isn't already owned by the 737 * top-level object, we have to copy it into a new page owned by the 738 * top-level object. 739 */ 740 if (fs.object != fs.first_object) { 741 /* 742 * We only really need to copy if we want to write it. 743 */ 744 if (fault_type & VM_PROT_WRITE) { 745 /* 746 * This allows pages to be virtually copied from a 747 * backing_object into the first_object, where the 748 * backing object has no other refs to it, and cannot 749 * gain any more refs. Instead of a bcopy, we just 750 * move the page from the backing object to the 751 * first object. Note that we must mark the page 752 * dirty in the first object so that it will go out 753 * to swap when needed. 754 */ 755 is_first_object_locked = FALSE; 756 if ( 757 /* 758 * Only one shadow object 759 */ 760 (fs.object->shadow_count == 1) && 761 /* 762 * No COW refs, except us 763 */ 764 (fs.object->ref_count == 1) && 765 /* 766 * No one else can look this object up 767 */ 768 (fs.object->handle == NULL) && 769 /* 770 * No other ways to look the object up 771 */ 772 ((fs.object->type == OBJT_DEFAULT) || 773 (fs.object->type == OBJT_SWAP)) && 774 (is_first_object_locked = VM_OBJECT_TRYLOCK(fs.first_object)) && 775 /* 776 * We don't chase down the shadow chain 777 */ 778 fs.object == fs.first_object->backing_object) { 779 vm_page_lock_queues(); 780 /* 781 * get rid of the unnecessary page 782 */ 783 vm_page_free(fs.first_m); 784 /* 785 * grab the page and put it into the 786 * process'es object. The page is 787 * automatically made dirty. 788 */ 789 vm_page_rename(fs.m, fs.first_object, fs.first_pindex); 790 vm_page_unlock_queues(); 791 vm_page_busy(fs.m); 792 fs.first_m = fs.m; 793 fs.m = NULL; 794 PCPU_INC(cnt.v_cow_optim); 795 } else { 796 /* 797 * Oh, well, lets copy it. 798 */ 799 pmap_copy_page(fs.m, fs.first_m); 800 fs.first_m->valid = VM_PAGE_BITS_ALL; 801 } 802 if (fs.m) { 803 /* 804 * We no longer need the old page or object. 805 */ 806 release_page(&fs); 807 } 808 /* 809 * fs.object != fs.first_object due to above 810 * conditional 811 */ 812 vm_object_pip_wakeup(fs.object); 813 VM_OBJECT_UNLOCK(fs.object); 814 /* 815 * Only use the new page below... 816 */ 817 fs.object = fs.first_object; 818 fs.pindex = fs.first_pindex; 819 fs.m = fs.first_m; 820 if (!is_first_object_locked) 821 VM_OBJECT_LOCK(fs.object); 822 PCPU_INC(cnt.v_cow_faults); 823 } else { 824 prot &= ~VM_PROT_WRITE; 825 } 826 } 827 828 /* 829 * We must verify that the maps have not changed since our last 830 * lookup. 831 */ 832 if (!fs.lookup_still_valid) { 833 vm_object_t retry_object; 834 vm_pindex_t retry_pindex; 835 vm_prot_t retry_prot; 836 837 if (!vm_map_trylock_read(fs.map)) { 838 release_page(&fs); 839 unlock_and_deallocate(&fs); 840 goto RetryFault; 841 } 842 fs.lookup_still_valid = TRUE; 843 if (fs.map->timestamp != map_generation) { 844 result = vm_map_lookup_locked(&fs.map, vaddr, fault_type, 845 &fs.entry, &retry_object, &retry_pindex, &retry_prot, &wired); 846 847 /* 848 * If we don't need the page any longer, put it on the inactive 849 * list (the easiest thing to do here). If no one needs it, 850 * pageout will grab it eventually. 851 */ 852 if (result != KERN_SUCCESS) { 853 release_page(&fs); 854 unlock_and_deallocate(&fs); 855 856 /* 857 * If retry of map lookup would have blocked then 858 * retry fault from start. 859 */ 860 if (result == KERN_FAILURE) 861 goto RetryFault; 862 return (result); 863 } 864 if ((retry_object != fs.first_object) || 865 (retry_pindex != fs.first_pindex)) { 866 release_page(&fs); 867 unlock_and_deallocate(&fs); 868 goto RetryFault; 869 } 870 871 /* 872 * Check whether the protection has changed or the object has 873 * been copied while we left the map unlocked. Changing from 874 * read to write permission is OK - we leave the page 875 * write-protected, and catch the write fault. Changing from 876 * write to read permission means that we can't mark the page 877 * write-enabled after all. 878 */ 879 prot &= retry_prot; 880 } 881 } 882 /* 883 * If the page was filled by a pager, update the map entry's 884 * last read offset. Since the pager does not return the 885 * actual set of pages that it read, this update is based on 886 * the requested set. Typically, the requested and actual 887 * sets are the same. 888 * 889 * XXX The following assignment modifies the map 890 * without holding a write lock on it. 891 */ 892 if (hardfault) 893 fs.entry->lastr = fs.pindex + faultcount - behind; 894 895 if (prot & VM_PROT_WRITE) { 896 vm_object_set_writeable_dirty(fs.object); 897 898 /* 899 * If the fault is a write, we know that this page is being 900 * written NOW so dirty it explicitly to save on 901 * pmap_is_modified() calls later. 902 * 903 * If this is a NOSYNC mmap we do not want to set VPO_NOSYNC 904 * if the page is already dirty to prevent data written with 905 * the expectation of being synced from not being synced. 906 * Likewise if this entry does not request NOSYNC then make 907 * sure the page isn't marked NOSYNC. Applications sharing 908 * data should use the same flags to avoid ping ponging. 909 * 910 * Also tell the backing pager, if any, that it should remove 911 * any swap backing since the page is now dirty. 912 */ 913 if (fs.entry->eflags & MAP_ENTRY_NOSYNC) { 914 if (fs.m->dirty == 0) 915 fs.m->oflags |= VPO_NOSYNC; 916 } else { 917 fs.m->oflags &= ~VPO_NOSYNC; 918 } 919 if (fault_flags & VM_FAULT_DIRTY) { 920 vm_page_dirty(fs.m); 921 vm_pager_page_unswapped(fs.m); 922 } 923 } 924 925 /* 926 * Page had better still be busy 927 */ 928 KASSERT(fs.m->oflags & VPO_BUSY, 929 ("vm_fault: page %p not busy!", fs.m)); 930 /* 931 * Page must be completely valid or it is not fit to 932 * map into user space. vm_pager_get_pages() ensures this. 933 */ 934 KASSERT(fs.m->valid == VM_PAGE_BITS_ALL, 935 ("vm_fault: page %p partially invalid", fs.m)); 936 VM_OBJECT_UNLOCK(fs.object); 937 938 /* 939 * Put this page into the physical map. We had to do the unlock above 940 * because pmap_enter() may sleep. We don't put the page 941 * back on the active queue until later so that the pageout daemon 942 * won't find it (yet). 943 */ 944 pmap_enter(fs.map->pmap, vaddr, fault_type, fs.m, prot, wired); 945 if (((fault_flags & VM_FAULT_WIRE_MASK) == 0) && (wired == 0)) { 946 vm_fault_prefault(fs.map->pmap, vaddr, fs.entry); 947 } 948 VM_OBJECT_LOCK(fs.object); 949 vm_page_lock_queues(); 950 vm_page_flag_set(fs.m, PG_REFERENCED); 951 952 /* 953 * If the page is not wired down, then put it where the pageout daemon 954 * can find it. 955 */ 956 if (fault_flags & VM_FAULT_WIRE_MASK) { 957 if (wired) 958 vm_page_wire(fs.m); 959 else 960 vm_page_unwire(fs.m, 1); 961 } else { 962 vm_page_activate(fs.m); 963 } 964 vm_page_unlock_queues(); 965 vm_page_wakeup(fs.m); 966 967 /* 968 * Unlock everything, and return 969 */ 970 unlock_and_deallocate(&fs); 971 if (hardfault) 972 curthread->td_ru.ru_majflt++; 973 else 974 curthread->td_ru.ru_minflt++; 975 976 return (KERN_SUCCESS); 977 } 978 979 /* 980 * vm_fault_prefault provides a quick way of clustering 981 * pagefaults into a processes address space. It is a "cousin" 982 * of vm_map_pmap_enter, except it runs at page fault time instead 983 * of mmap time. 984 */ 985 static void 986 vm_fault_prefault(pmap_t pmap, vm_offset_t addra, vm_map_entry_t entry) 987 { 988 int i; 989 vm_offset_t addr, starta; 990 vm_pindex_t pindex; 991 vm_page_t m; 992 vm_object_t object; 993 994 if (pmap != vmspace_pmap(curthread->td_proc->p_vmspace)) 995 return; 996 997 object = entry->object.vm_object; 998 999 starta = addra - PFBAK * PAGE_SIZE; 1000 if (starta < entry->start) { 1001 starta = entry->start; 1002 } else if (starta > addra) { 1003 starta = 0; 1004 } 1005 1006 for (i = 0; i < PAGEORDER_SIZE; i++) { 1007 vm_object_t backing_object, lobject; 1008 1009 addr = addra + prefault_pageorder[i]; 1010 if (addr > addra + (PFFOR * PAGE_SIZE)) 1011 addr = 0; 1012 1013 if (addr < starta || addr >= entry->end) 1014 continue; 1015 1016 if (!pmap_is_prefaultable(pmap, addr)) 1017 continue; 1018 1019 pindex = ((addr - entry->start) + entry->offset) >> PAGE_SHIFT; 1020 lobject = object; 1021 VM_OBJECT_LOCK(lobject); 1022 while ((m = vm_page_lookup(lobject, pindex)) == NULL && 1023 lobject->type == OBJT_DEFAULT && 1024 (backing_object = lobject->backing_object) != NULL) { 1025 KASSERT((lobject->backing_object_offset & PAGE_MASK) == 1026 0, ("vm_fault_prefault: unaligned object offset")); 1027 pindex += lobject->backing_object_offset >> PAGE_SHIFT; 1028 VM_OBJECT_LOCK(backing_object); 1029 VM_OBJECT_UNLOCK(lobject); 1030 lobject = backing_object; 1031 } 1032 /* 1033 * give-up when a page is not in memory 1034 */ 1035 if (m == NULL) { 1036 VM_OBJECT_UNLOCK(lobject); 1037 break; 1038 } 1039 if (m->valid == VM_PAGE_BITS_ALL && 1040 (m->flags & PG_FICTITIOUS) == 0) { 1041 vm_page_lock_queues(); 1042 pmap_enter_quick(pmap, addr, m, entry->protection); 1043 vm_page_unlock_queues(); 1044 } 1045 VM_OBJECT_UNLOCK(lobject); 1046 } 1047 } 1048 1049 /* 1050 * vm_fault_quick: 1051 * 1052 * Ensure that the requested virtual address, which may be in userland, 1053 * is valid. Fault-in the page if necessary. Return -1 on failure. 1054 */ 1055 int 1056 vm_fault_quick(caddr_t v, int prot) 1057 { 1058 int r; 1059 1060 if (prot & VM_PROT_WRITE) 1061 r = subyte(v, fubyte(v)); 1062 else 1063 r = fubyte(v); 1064 return(r); 1065 } 1066 1067 /* 1068 * vm_fault_wire: 1069 * 1070 * Wire down a range of virtual addresses in a map. 1071 */ 1072 int 1073 vm_fault_wire(vm_map_t map, vm_offset_t start, vm_offset_t end, 1074 boolean_t user_wire, boolean_t fictitious) 1075 { 1076 vm_offset_t va; 1077 int rv; 1078 1079 /* 1080 * We simulate a fault to get the page and enter it in the physical 1081 * map. For user wiring, we only ask for read access on currently 1082 * read-only sections. 1083 */ 1084 for (va = start; va < end; va += PAGE_SIZE) { 1085 rv = vm_fault(map, va, 1086 user_wire ? VM_PROT_READ : VM_PROT_READ | VM_PROT_WRITE, 1087 user_wire ? VM_FAULT_USER_WIRE : VM_FAULT_CHANGE_WIRING); 1088 if (rv) { 1089 if (va != start) 1090 vm_fault_unwire(map, start, va, fictitious); 1091 return (rv); 1092 } 1093 } 1094 return (KERN_SUCCESS); 1095 } 1096 1097 /* 1098 * vm_fault_unwire: 1099 * 1100 * Unwire a range of virtual addresses in a map. 1101 */ 1102 void 1103 vm_fault_unwire(vm_map_t map, vm_offset_t start, vm_offset_t end, 1104 boolean_t fictitious) 1105 { 1106 vm_paddr_t pa; 1107 vm_offset_t va; 1108 pmap_t pmap; 1109 1110 pmap = vm_map_pmap(map); 1111 1112 /* 1113 * Since the pages are wired down, we must be able to get their 1114 * mappings from the physical map system. 1115 */ 1116 for (va = start; va < end; va += PAGE_SIZE) { 1117 pa = pmap_extract(pmap, va); 1118 if (pa != 0) { 1119 pmap_change_wiring(pmap, va, FALSE); 1120 if (!fictitious) { 1121 vm_page_lock_queues(); 1122 vm_page_unwire(PHYS_TO_VM_PAGE(pa), 1); 1123 vm_page_unlock_queues(); 1124 } 1125 } 1126 } 1127 } 1128 1129 /* 1130 * Routine: 1131 * vm_fault_copy_entry 1132 * Function: 1133 * Create new shadow object backing dst_entry with private copy of 1134 * all underlying pages. When src_entry is equal to dst_entry, 1135 * function implements COW for wired-down map entry. Otherwise, 1136 * it forks wired entry into dst_map. 1137 * 1138 * In/out conditions: 1139 * The source and destination maps must be locked for write. 1140 * The source map entry must be wired down (or be a sharing map 1141 * entry corresponding to a main map entry that is wired down). 1142 */ 1143 void 1144 vm_fault_copy_entry(vm_map_t dst_map, vm_map_t src_map, 1145 vm_map_entry_t dst_entry, vm_map_entry_t src_entry, 1146 vm_ooffset_t *fork_charge) 1147 { 1148 vm_object_t backing_object, dst_object, object, src_object; 1149 vm_pindex_t dst_pindex, pindex, src_pindex; 1150 vm_prot_t access, prot; 1151 vm_offset_t vaddr; 1152 vm_page_t dst_m; 1153 vm_page_t src_m; 1154 boolean_t src_readonly, upgrade; 1155 1156 #ifdef lint 1157 src_map++; 1158 #endif /* lint */ 1159 1160 upgrade = src_entry == dst_entry; 1161 1162 src_object = src_entry->object.vm_object; 1163 src_pindex = OFF_TO_IDX(src_entry->offset); 1164 src_readonly = (src_entry->protection & VM_PROT_WRITE) == 0; 1165 1166 /* 1167 * Create the top-level object for the destination entry. (Doesn't 1168 * actually shadow anything - we copy the pages directly.) 1169 */ 1170 dst_object = vm_object_allocate(OBJT_DEFAULT, 1171 OFF_TO_IDX(dst_entry->end - dst_entry->start)); 1172 #if VM_NRESERVLEVEL > 0 1173 dst_object->flags |= OBJ_COLORED; 1174 dst_object->pg_color = atop(dst_entry->start); 1175 #endif 1176 1177 VM_OBJECT_LOCK(dst_object); 1178 KASSERT(upgrade || dst_entry->object.vm_object == NULL, 1179 ("vm_fault_copy_entry: vm_object not NULL")); 1180 dst_entry->object.vm_object = dst_object; 1181 dst_entry->offset = 0; 1182 dst_object->charge = dst_entry->end - dst_entry->start; 1183 if (fork_charge != NULL) { 1184 KASSERT(dst_entry->uip == NULL, 1185 ("vm_fault_copy_entry: leaked swp charge")); 1186 dst_object->uip = curthread->td_ucred->cr_ruidinfo; 1187 uihold(dst_object->uip); 1188 *fork_charge += dst_object->charge; 1189 } else { 1190 dst_object->uip = dst_entry->uip; 1191 dst_entry->uip = NULL; 1192 } 1193 access = prot = dst_entry->max_protection; 1194 /* 1195 * If not an upgrade, then enter the mappings in the pmap as 1196 * read and/or execute accesses. Otherwise, enter them as 1197 * write accesses. 1198 * 1199 * A writeable large page mapping is only created if all of 1200 * the constituent small page mappings are modified. Marking 1201 * PTEs as modified on inception allows promotion to happen 1202 * without taking potentially large number of soft faults. 1203 */ 1204 if (!upgrade) 1205 access &= ~VM_PROT_WRITE; 1206 1207 /* 1208 * Loop through all of the pages in the entry's range, copying each 1209 * one from the source object (it should be there) to the destination 1210 * object. 1211 */ 1212 for (vaddr = dst_entry->start, dst_pindex = 0; 1213 vaddr < dst_entry->end; 1214 vaddr += PAGE_SIZE, dst_pindex++) { 1215 1216 /* 1217 * Allocate a page in the destination object. 1218 */ 1219 do { 1220 dst_m = vm_page_alloc(dst_object, dst_pindex, 1221 VM_ALLOC_NORMAL); 1222 if (dst_m == NULL) { 1223 VM_OBJECT_UNLOCK(dst_object); 1224 VM_WAIT; 1225 VM_OBJECT_LOCK(dst_object); 1226 } 1227 } while (dst_m == NULL); 1228 1229 /* 1230 * Find the page in the source object, and copy it in. 1231 * (Because the source is wired down, the page will be in 1232 * memory.) 1233 */ 1234 VM_OBJECT_LOCK(src_object); 1235 object = src_object; 1236 pindex = src_pindex + dst_pindex; 1237 while ((src_m = vm_page_lookup(object, pindex)) == NULL && 1238 src_readonly && 1239 (backing_object = object->backing_object) != NULL) { 1240 /* 1241 * Allow fallback to backing objects if we are reading. 1242 */ 1243 VM_OBJECT_LOCK(backing_object); 1244 pindex += OFF_TO_IDX(object->backing_object_offset); 1245 VM_OBJECT_UNLOCK(object); 1246 object = backing_object; 1247 } 1248 if (src_m == NULL) 1249 panic("vm_fault_copy_wired: page missing"); 1250 pmap_copy_page(src_m, dst_m); 1251 VM_OBJECT_UNLOCK(object); 1252 dst_m->valid = VM_PAGE_BITS_ALL; 1253 VM_OBJECT_UNLOCK(dst_object); 1254 1255 /* 1256 * Enter it in the pmap. If a wired, copy-on-write 1257 * mapping is being replaced by a write-enabled 1258 * mapping, then wire that new mapping. 1259 */ 1260 pmap_enter(dst_map->pmap, vaddr, access, dst_m, prot, upgrade); 1261 1262 /* 1263 * Mark it no longer busy, and put it on the active list. 1264 */ 1265 VM_OBJECT_LOCK(dst_object); 1266 vm_page_lock_queues(); 1267 if (upgrade) { 1268 vm_page_unwire(src_m, 0); 1269 vm_page_wire(dst_m); 1270 } else 1271 vm_page_activate(dst_m); 1272 vm_page_unlock_queues(); 1273 vm_page_wakeup(dst_m); 1274 } 1275 VM_OBJECT_UNLOCK(dst_object); 1276 if (upgrade) { 1277 dst_entry->eflags &= ~(MAP_ENTRY_COW | MAP_ENTRY_NEEDS_COPY); 1278 vm_object_deallocate(src_object); 1279 } 1280 } 1281 1282 1283 /* 1284 * This routine checks around the requested page for other pages that 1285 * might be able to be faulted in. This routine brackets the viable 1286 * pages for the pages to be paged in. 1287 * 1288 * Inputs: 1289 * m, rbehind, rahead 1290 * 1291 * Outputs: 1292 * marray (array of vm_page_t), reqpage (index of requested page) 1293 * 1294 * Return value: 1295 * number of pages in marray 1296 */ 1297 static int 1298 vm_fault_additional_pages(m, rbehind, rahead, marray, reqpage) 1299 vm_page_t m; 1300 int rbehind; 1301 int rahead; 1302 vm_page_t *marray; 1303 int *reqpage; 1304 { 1305 int i,j; 1306 vm_object_t object; 1307 vm_pindex_t pindex, startpindex, endpindex, tpindex; 1308 vm_page_t rtm; 1309 int cbehind, cahead; 1310 1311 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 1312 1313 object = m->object; 1314 pindex = m->pindex; 1315 cbehind = cahead = 0; 1316 1317 /* 1318 * if the requested page is not available, then give up now 1319 */ 1320 if (!vm_pager_has_page(object, pindex, &cbehind, &cahead)) { 1321 return 0; 1322 } 1323 1324 if ((cbehind == 0) && (cahead == 0)) { 1325 *reqpage = 0; 1326 marray[0] = m; 1327 return 1; 1328 } 1329 1330 if (rahead > cahead) { 1331 rahead = cahead; 1332 } 1333 1334 if (rbehind > cbehind) { 1335 rbehind = cbehind; 1336 } 1337 1338 /* 1339 * scan backward for the read behind pages -- in memory 1340 */ 1341 if (pindex > 0) { 1342 if (rbehind > pindex) { 1343 rbehind = pindex; 1344 startpindex = 0; 1345 } else { 1346 startpindex = pindex - rbehind; 1347 } 1348 1349 if ((rtm = TAILQ_PREV(m, pglist, listq)) != NULL && 1350 rtm->pindex >= startpindex) 1351 startpindex = rtm->pindex + 1; 1352 1353 /* tpindex is unsigned; beware of numeric underflow. */ 1354 for (i = 0, tpindex = pindex - 1; tpindex >= startpindex && 1355 tpindex < pindex; i++, tpindex--) { 1356 1357 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL | 1358 VM_ALLOC_IFNOTCACHED); 1359 if (rtm == NULL) { 1360 /* 1361 * Shift the allocated pages to the 1362 * beginning of the array. 1363 */ 1364 for (j = 0; j < i; j++) { 1365 marray[j] = marray[j + tpindex + 1 - 1366 startpindex]; 1367 } 1368 break; 1369 } 1370 1371 marray[tpindex - startpindex] = rtm; 1372 } 1373 } else { 1374 startpindex = 0; 1375 i = 0; 1376 } 1377 1378 marray[i] = m; 1379 /* page offset of the required page */ 1380 *reqpage = i; 1381 1382 tpindex = pindex + 1; 1383 i++; 1384 1385 /* 1386 * scan forward for the read ahead pages 1387 */ 1388 endpindex = tpindex + rahead; 1389 if ((rtm = TAILQ_NEXT(m, listq)) != NULL && rtm->pindex < endpindex) 1390 endpindex = rtm->pindex; 1391 if (endpindex > object->size) 1392 endpindex = object->size; 1393 1394 for (; tpindex < endpindex; i++, tpindex++) { 1395 1396 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL | 1397 VM_ALLOC_IFNOTCACHED); 1398 if (rtm == NULL) { 1399 break; 1400 } 1401 1402 marray[i] = rtm; 1403 } 1404 1405 /* return number of pages */ 1406 return i; 1407 }
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