vfs_bio.c revision 9530
1/* 2 * Copyright (c) 1994 John S. Dyson 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice immediately at the beginning of the file, without modification, 10 * this list of conditions, and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. Absolutely no warranty of function or purpose is made by the author 15 * John S. Dyson. 16 * 4. This work was done expressly for inclusion into FreeBSD. Other use 17 * is allowed if this notation is included. 18 * 5. Modifications may be freely made to this file if the above conditions 19 * are met. 20 * 21 * $Id: vfs_bio.c,v 1.47 1995/06/28 12:00:54 davidg Exp $ 22 */ 23 24/* 25 * this file contains a new buffer I/O scheme implementing a coherent 26 * VM object and buffer cache scheme. Pains have been taken to make 27 * sure that the performance degradation associated with schemes such 28 * as this is not realized. 29 * 30 * Author: John S. Dyson 31 * Significant help during the development and debugging phases 32 * had been provided by David Greenman, also of the FreeBSD core team. 33 */ 34 35#define VMIO 36#include <sys/param.h> 37#include <sys/systm.h> 38#include <sys/kernel.h> 39#include <sys/proc.h> 40#include <sys/vnode.h> 41#include <vm/vm.h> 42#include <vm/vm_kern.h> 43#include <vm/vm_pageout.h> 44#include <vm/vm_page.h> 45#include <vm/vm_object.h> 46#include <sys/buf.h> 47#include <sys/mount.h> 48#include <sys/malloc.h> 49#include <sys/resourcevar.h> 50#include <sys/proc.h> 51 52#include <miscfs/specfs/specdev.h> 53 54struct buf *buf; /* buffer header pool */ 55int nbuf; /* number of buffer headers calculated 56 * elsewhere */ 57struct swqueue bswlist; 58 59void vm_hold_free_pages(struct buf * bp, vm_offset_t from, vm_offset_t to); 60void vm_hold_load_pages(struct buf * bp, vm_offset_t from, vm_offset_t to); 61void vfs_clean_pages(struct buf * bp); 62static void vfs_setdirty(struct buf *bp); 63 64int needsbuffer; 65 66/* 67 * Internal update daemon, process 3 68 * The variable vfs_update_wakeup allows for internal syncs. 69 */ 70int vfs_update_wakeup; 71 72 73/* 74 * buffers base kva 75 */ 76caddr_t buffers_kva; 77 78/* 79 * bogus page -- for I/O to/from partially complete buffers 80 * this is a temporary solution to the problem, but it is not 81 * really that bad. it would be better to split the buffer 82 * for input in the case of buffers partially already in memory, 83 * but the code is intricate enough already. 84 */ 85vm_page_t bogus_page; 86vm_offset_t bogus_offset; 87 88int bufspace, maxbufspace; 89 90/* 91 * advisory minimum for size of LRU queue or VMIO queue 92 */ 93int minbuf; 94 95/* 96 * Initialize buffer headers and related structures. 97 */ 98void 99bufinit() 100{ 101 struct buf *bp; 102 int i; 103 104 TAILQ_INIT(&bswlist); 105 LIST_INIT(&invalhash); 106 107 /* first, make a null hash table */ 108 for (i = 0; i < BUFHSZ; i++) 109 LIST_INIT(&bufhashtbl[i]); 110 111 /* next, make a null set of free lists */ 112 for (i = 0; i < BUFFER_QUEUES; i++) 113 TAILQ_INIT(&bufqueues[i]); 114 115 buffers_kva = (caddr_t) kmem_alloc_pageable(buffer_map, MAXBSIZE * nbuf); 116 /* finally, initialize each buffer header and stick on empty q */ 117 for (i = 0; i < nbuf; i++) { 118 bp = &buf[i]; 119 bzero(bp, sizeof *bp); 120 bp->b_flags = B_INVAL; /* we're just an empty header */ 121 bp->b_dev = NODEV; 122 bp->b_rcred = NOCRED; 123 bp->b_wcred = NOCRED; 124 bp->b_qindex = QUEUE_EMPTY; 125 bp->b_vnbufs.le_next = NOLIST; 126 bp->b_data = buffers_kva + i * MAXBSIZE; 127 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 128 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 129 } 130/* 131 * maxbufspace is currently calculated to support all filesystem blocks 132 * to be 8K. If you happen to use a 16K filesystem, the size of the buffer 133 * cache is still the same as it would be for 8K filesystems. This 134 * keeps the size of the buffer cache "in check" for big block filesystems. 135 */ 136 minbuf = nbuf / 3; 137 maxbufspace = 2 * (nbuf + 8) * PAGE_SIZE; 138 139 bogus_offset = kmem_alloc_pageable(kernel_map, PAGE_SIZE); 140 bogus_page = vm_page_alloc(kernel_object, 141 bogus_offset - VM_MIN_KERNEL_ADDRESS, VM_ALLOC_NORMAL); 142 143} 144 145/* 146 * remove the buffer from the appropriate free list 147 */ 148void 149bremfree(struct buf * bp) 150{ 151 int s = splbio(); 152 153 if (bp->b_qindex != QUEUE_NONE) { 154 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 155 bp->b_qindex = QUEUE_NONE; 156 } else { 157 panic("bremfree: removing a buffer when not on a queue"); 158 } 159 splx(s); 160} 161 162/* 163 * Get a buffer with the specified data. Look in the cache first. 164 */ 165int 166bread(struct vnode * vp, daddr_t blkno, int size, struct ucred * cred, 167 struct buf ** bpp) 168{ 169 struct buf *bp; 170 171 bp = getblk(vp, blkno, size, 0, 0); 172 *bpp = bp; 173 174 /* if not found in cache, do some I/O */ 175 if ((bp->b_flags & B_CACHE) == 0) { 176 if (curproc != NULL) 177 curproc->p_stats->p_ru.ru_inblock++; 178 bp->b_flags |= B_READ; 179 bp->b_flags &= ~(B_DONE | B_ERROR | B_INVAL); 180 if (bp->b_rcred == NOCRED) { 181 if (cred != NOCRED) 182 crhold(cred); 183 bp->b_rcred = cred; 184 } 185 vfs_busy_pages(bp, 0); 186 VOP_STRATEGY(bp); 187 return (biowait(bp)); 188 } 189 return (0); 190} 191 192/* 193 * Operates like bread, but also starts asynchronous I/O on 194 * read-ahead blocks. 195 */ 196int 197breadn(struct vnode * vp, daddr_t blkno, int size, 198 daddr_t * rablkno, int *rabsize, 199 int cnt, struct ucred * cred, struct buf ** bpp) 200{ 201 struct buf *bp, *rabp; 202 int i; 203 int rv = 0, readwait = 0; 204 205 *bpp = bp = getblk(vp, blkno, size, 0, 0); 206 207 /* if not found in cache, do some I/O */ 208 if ((bp->b_flags & B_CACHE) == 0) { 209 if (curproc != NULL) 210 curproc->p_stats->p_ru.ru_inblock++; 211 bp->b_flags |= B_READ; 212 bp->b_flags &= ~(B_DONE | B_ERROR | B_INVAL); 213 if (bp->b_rcred == NOCRED) { 214 if (cred != NOCRED) 215 crhold(cred); 216 bp->b_rcred = cred; 217 } 218 vfs_busy_pages(bp, 0); 219 VOP_STRATEGY(bp); 220 ++readwait; 221 } 222 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 223 if (inmem(vp, *rablkno)) 224 continue; 225 rabp = getblk(vp, *rablkno, *rabsize, 0, 0); 226 227 if ((rabp->b_flags & B_CACHE) == 0) { 228 if (curproc != NULL) 229 curproc->p_stats->p_ru.ru_inblock++; 230 rabp->b_flags |= B_READ | B_ASYNC; 231 rabp->b_flags &= ~(B_DONE | B_ERROR | B_INVAL); 232 if (rabp->b_rcred == NOCRED) { 233 if (cred != NOCRED) 234 crhold(cred); 235 rabp->b_rcred = cred; 236 } 237 vfs_busy_pages(rabp, 0); 238 VOP_STRATEGY(rabp); 239 } else { 240 brelse(rabp); 241 } 242 } 243 244 if (readwait) { 245 rv = biowait(bp); 246 } 247 return (rv); 248} 249 250/* 251 * Write, release buffer on completion. (Done by iodone 252 * if async.) 253 */ 254int 255bwrite(struct buf * bp) 256{ 257 int oldflags = bp->b_flags; 258 259 if (bp->b_flags & B_INVAL) { 260 brelse(bp); 261 return (0); 262 } 263 if (!(bp->b_flags & B_BUSY)) 264 panic("bwrite: buffer is not busy???"); 265 266 bp->b_flags &= ~(B_READ | B_DONE | B_ERROR | B_DELWRI); 267 bp->b_flags |= B_WRITEINPROG; 268 269 if ((oldflags & (B_ASYNC|B_DELWRI)) == (B_ASYNC|B_DELWRI)) { 270 reassignbuf(bp, bp->b_vp); 271 } 272 273 bp->b_vp->v_numoutput++; 274 vfs_busy_pages(bp, 1); 275 if (curproc != NULL) 276 curproc->p_stats->p_ru.ru_oublock++; 277 VOP_STRATEGY(bp); 278 279 if ((oldflags & B_ASYNC) == 0) { 280 int rtval = biowait(bp); 281 282 if (oldflags & B_DELWRI) { 283 reassignbuf(bp, bp->b_vp); 284 } 285 brelse(bp); 286 return (rtval); 287 } 288 return (0); 289} 290 291int 292vn_bwrite(ap) 293 struct vop_bwrite_args *ap; 294{ 295 return (bwrite(ap->a_bp)); 296} 297 298/* 299 * Delayed write. (Buffer is marked dirty). 300 */ 301void 302bdwrite(struct buf * bp) 303{ 304 305 if ((bp->b_flags & B_BUSY) == 0) { 306 panic("bdwrite: buffer is not busy"); 307 } 308 if (bp->b_flags & B_INVAL) { 309 brelse(bp); 310 return; 311 } 312 if (bp->b_flags & B_TAPE) { 313 bawrite(bp); 314 return; 315 } 316 bp->b_flags &= ~(B_READ|B_RELBUF); 317 if ((bp->b_flags & B_DELWRI) == 0) { 318 bp->b_flags |= B_DONE | B_DELWRI; 319 reassignbuf(bp, bp->b_vp); 320 } 321 322 /* 323 * This bmap keeps the system from needing to do the bmap later, 324 * perhaps when the system is attempting to do a sync. Since it 325 * is likely that the indirect block -- or whatever other datastructure 326 * that the filesystem needs is still in memory now, it is a good 327 * thing to do this. Note also, that if the pageout daemon is 328 * requesting a sync -- there might not be enough memory to do 329 * the bmap then... So, this is important to do. 330 */ 331 if( bp->b_lblkno == bp->b_blkno) { 332 VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL); 333 } 334 335 /* 336 * Set the *dirty* buffer range based upon the VM system dirty pages. 337 */ 338 vfs_setdirty(bp); 339 340 /* 341 * We need to do this here to satisfy the vnode_pager and the 342 * pageout daemon, so that it thinks that the pages have been 343 * "cleaned". Note that since the pages are in a delayed write 344 * buffer -- the VFS layer "will" see that the pages get written 345 * out on the next sync, or perhaps the cluster will be completed. 346 */ 347 vfs_clean_pages(bp); 348 brelse(bp); 349 return; 350} 351 352/* 353 * Asynchronous write. 354 * Start output on a buffer, but do not wait for it to complete. 355 * The buffer is released when the output completes. 356 */ 357void 358bawrite(struct buf * bp) 359{ 360 bp->b_flags |= B_ASYNC; 361 (void) VOP_BWRITE(bp); 362} 363 364/* 365 * Release a buffer. 366 */ 367void 368brelse(struct buf * bp) 369{ 370 int s; 371 372 if (bp->b_flags & B_CLUSTER) { 373 relpbuf(bp); 374 return; 375 } 376 /* anyone need a "free" block? */ 377 s = splbio(); 378 379 if (needsbuffer) { 380 needsbuffer = 0; 381 wakeup((caddr_t) &needsbuffer); 382 } 383 384 /* anyone need this block? */ 385 if (bp->b_flags & B_WANTED) { 386 bp->b_flags &= ~B_WANTED | B_AGE; 387 wakeup((caddr_t) bp); 388 } else if (bp->b_flags & B_VMIO) { 389 bp->b_flags &= ~B_WANTED; 390 wakeup((caddr_t) bp); 391 } 392 if (bp->b_flags & B_LOCKED) 393 bp->b_flags &= ~B_ERROR; 394 395 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR)) || 396 (bp->b_bufsize <= 0)) { 397 bp->b_flags |= B_INVAL; 398 bp->b_flags &= ~(B_DELWRI | B_CACHE); 399 if (((bp->b_flags & B_VMIO) == 0) && bp->b_vp) 400 brelvp(bp); 401 } 402 403 /* 404 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 405 * constituted, so the B_INVAL flag is used to *invalidate* the buffer, 406 * but the VM object is kept around. The B_NOCACHE flag is used to 407 * invalidate the pages in the VM object. 408 */ 409 if (bp->b_flags & B_VMIO) { 410 vm_offset_t foff; 411 vm_object_t obj; 412 int i, resid; 413 vm_page_t m; 414 int iototal = bp->b_bufsize; 415 416 foff = 0; 417 obj = 0; 418 if (bp->b_npages) { 419 if (bp->b_vp && bp->b_vp->v_mount) { 420 foff = bp->b_vp->v_mount->mnt_stat.f_iosize * bp->b_lblkno; 421 } else { 422 /* 423 * vnode pointer has been ripped away -- 424 * probably file gone... 425 */ 426 foff = bp->b_pages[0]->offset; 427 } 428 } 429 for (i = 0; i < bp->b_npages; i++) { 430 m = bp->b_pages[i]; 431 if (m == bogus_page) { 432 m = vm_page_lookup(obj, foff); 433 if (!m) { 434 panic("brelse: page missing\n"); 435 } 436 bp->b_pages[i] = m; 437 pmap_qenter(trunc_page(bp->b_data), bp->b_pages, bp->b_npages); 438 } 439 resid = (m->offset + PAGE_SIZE) - foff; 440 if (resid > iototal) 441 resid = iototal; 442 if (resid > 0) { 443 /* 444 * Don't invalidate the page if the local machine has already 445 * modified it. This is the lesser of two evils, and should 446 * be fixed. 447 */ 448 if (bp->b_flags & (B_NOCACHE | B_ERROR)) { 449 vm_page_test_dirty(m); 450 if (m->dirty == 0) { 451 vm_page_set_invalid(m, foff, resid); 452 if (m->valid == 0) 453 vm_page_protect(m, VM_PROT_NONE); 454 } 455 } 456 } 457 foff += resid; 458 iototal -= resid; 459 } 460 461 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 462 for(i=0;i<bp->b_npages;i++) { 463 m = bp->b_pages[i]; 464 --m->bmapped; 465 if (m->bmapped == 0) { 466 if (m->flags & PG_WANTED) { 467 wakeup((caddr_t) m); 468 m->flags &= ~PG_WANTED; 469 } 470 vm_page_test_dirty(m); 471 if ((m->dirty & m->valid) == 0 && 472 (m->flags & PG_REFERENCED) == 0 && 473 !pmap_is_referenced(VM_PAGE_TO_PHYS(m))) { 474 vm_page_cache(m); 475 } else if ((m->flags & PG_ACTIVE) == 0) { 476 vm_page_activate(m); 477 m->act_count = 0; 478 } 479 } 480 } 481 bufspace -= bp->b_bufsize; 482 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages); 483 bp->b_npages = 0; 484 bp->b_bufsize = 0; 485 bp->b_flags &= ~B_VMIO; 486 if (bp->b_vp) 487 brelvp(bp); 488 } 489 } 490 if (bp->b_qindex != QUEUE_NONE) 491 panic("brelse: free buffer onto another queue???"); 492 493 /* enqueue */ 494 /* buffers with no memory */ 495 if (bp->b_bufsize == 0) { 496 bp->b_qindex = QUEUE_EMPTY; 497 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 498 LIST_REMOVE(bp, b_hash); 499 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 500 bp->b_dev = NODEV; 501 /* buffers with junk contents */ 502 } else if (bp->b_flags & (B_ERROR | B_INVAL | B_NOCACHE | B_RELBUF)) { 503 bp->b_qindex = QUEUE_AGE; 504 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_AGE], bp, b_freelist); 505 LIST_REMOVE(bp, b_hash); 506 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 507 bp->b_dev = NODEV; 508 /* buffers that are locked */ 509 } else if (bp->b_flags & B_LOCKED) { 510 bp->b_qindex = QUEUE_LOCKED; 511 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LOCKED], bp, b_freelist); 512 /* buffers with stale but valid contents */ 513 } else if (bp->b_flags & B_AGE) { 514 bp->b_qindex = QUEUE_AGE; 515 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_AGE], bp, b_freelist); 516 /* buffers with valid and quite potentially reuseable contents */ 517 } else { 518 bp->b_qindex = QUEUE_LRU; 519 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LRU], bp, b_freelist); 520 } 521 522 /* unlock */ 523 bp->b_flags &= ~(B_WANTED | B_BUSY | B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 524 splx(s); 525} 526 527/* 528 * this routine implements clustered async writes for 529 * clearing out B_DELWRI buffers... This is much better 530 * than the old way of writing only one buffer at a time. 531 */ 532void 533vfs_bio_awrite(struct buf * bp) 534{ 535 int i; 536 daddr_t lblkno = bp->b_lblkno; 537 struct vnode *vp = bp->b_vp; 538 int s; 539 int ncl; 540 struct buf *bpa; 541 542 s = splbio(); 543 if( vp->v_mount && (vp->v_flag & VVMIO) && 544 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 545 int size = vp->v_mount->mnt_stat.f_iosize; 546 547 for (i = 1; i < MAXPHYS / size; i++) { 548 if ((bpa = incore(vp, lblkno + i)) && 549 ((bpa->b_flags & (B_BUSY | B_DELWRI | B_BUSY | B_CLUSTEROK | B_INVAL)) == B_DELWRI | B_CLUSTEROK) && 550 (bpa->b_bufsize == size)) { 551 if ((bpa->b_blkno == bpa->b_lblkno) || 552 (bpa->b_blkno != bp->b_blkno + (i * size) / DEV_BSIZE)) 553 break; 554 } else { 555 break; 556 } 557 } 558 ncl = i; 559 /* 560 * this is a possible cluster write 561 */ 562 if (ncl != 1) { 563 bremfree(bp); 564 cluster_wbuild(vp, bp, size, lblkno, ncl, -1); 565 splx(s); 566 return; 567 } 568 } 569 /* 570 * default (old) behavior, writing out only one block 571 */ 572 bremfree(bp); 573 bp->b_flags |= B_BUSY | B_ASYNC; 574 (void) VOP_BWRITE(bp); 575 splx(s); 576} 577 578 579/* 580 * Find a buffer header which is available for use. 581 */ 582static struct buf * 583getnewbuf(int slpflag, int slptimeo, int doingvmio) 584{ 585 struct buf *bp; 586 int s; 587 int firstbp = 1; 588 589 s = splbio(); 590start: 591 if (bufspace >= maxbufspace) 592 goto trytofreespace; 593 594 /* can we constitute a new buffer? */ 595 if ((bp = bufqueues[QUEUE_EMPTY].tqh_first)) { 596 if (bp->b_qindex != QUEUE_EMPTY) 597 panic("getnewbuf: inconsistent EMPTY queue"); 598 bremfree(bp); 599 goto fillbuf; 600 } 601trytofreespace: 602 /* 603 * We keep the file I/O from hogging metadata I/O 604 * This is desirable because file data is cached in the 605 * VM/Buffer cache even if a buffer is freed. 606 */ 607 if ((bp = bufqueues[QUEUE_AGE].tqh_first)) { 608 if (bp->b_qindex != QUEUE_AGE) 609 panic("getnewbuf: inconsistent AGE queue"); 610 } else if ((bp = bufqueues[QUEUE_LRU].tqh_first)) { 611 if (bp->b_qindex != QUEUE_LRU) 612 panic("getnewbuf: inconsistent LRU queue"); 613 } 614 if (!bp) { 615 /* wait for a free buffer of any kind */ 616 needsbuffer = 1; 617 tsleep((caddr_t) &needsbuffer, PRIBIO | slpflag, "newbuf", slptimeo); 618 splx(s); 619 return (0); 620 } 621 622 /* if we are a delayed write, convert to an async write */ 623 if ((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI) { 624 vfs_bio_awrite(bp); 625 if (!slpflag && !slptimeo) { 626 splx(s); 627 return (0); 628 } 629 goto start; 630 } 631 632 if (bp->b_flags & B_WANTED) { 633 bp->b_flags &= ~B_WANTED; 634 wakeup((caddr_t) bp); 635 } 636 bremfree(bp); 637 638 if (bp->b_flags & B_VMIO) { 639 bp->b_flags |= B_RELBUF | B_BUSY | B_DONE; 640 brelse(bp); 641 bremfree(bp); 642 } 643 644 if (bp->b_vp) 645 brelvp(bp); 646 647 /* we are not free, nor do we contain interesting data */ 648 if (bp->b_rcred != NOCRED) 649 crfree(bp->b_rcred); 650 if (bp->b_wcred != NOCRED) 651 crfree(bp->b_wcred); 652fillbuf: 653 bp->b_flags |= B_BUSY; 654 LIST_REMOVE(bp, b_hash); 655 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 656 splx(s); 657 if (bp->b_bufsize) { 658 allocbuf(bp, 0); 659 } 660 bp->b_flags = B_BUSY; 661 bp->b_dev = NODEV; 662 bp->b_vp = NULL; 663 bp->b_blkno = bp->b_lblkno = 0; 664 bp->b_iodone = 0; 665 bp->b_error = 0; 666 bp->b_resid = 0; 667 bp->b_bcount = 0; 668 bp->b_npages = 0; 669 bp->b_wcred = bp->b_rcred = NOCRED; 670 bp->b_data = buffers_kva + (bp - buf) * MAXBSIZE; 671 bp->b_dirtyoff = bp->b_dirtyend = 0; 672 bp->b_validoff = bp->b_validend = 0; 673 if (bufspace >= maxbufspace) { 674 s = splbio(); 675 bp->b_flags |= B_INVAL; 676 brelse(bp); 677 goto trytofreespace; 678 } 679 return (bp); 680} 681 682/* 683 * Check to see if a block is currently memory resident. 684 */ 685struct buf * 686incore(struct vnode * vp, daddr_t blkno) 687{ 688 struct buf *bp; 689 struct bufhashhdr *bh; 690 691 int s = splbio(); 692 693 bh = BUFHASH(vp, blkno); 694 bp = bh->lh_first; 695 696 /* Search hash chain */ 697 while (bp) { 698 /* hit */ 699 if (bp->b_lblkno == blkno && bp->b_vp == vp && 700 (bp->b_flags & B_INVAL) == 0) { 701 splx(s); 702 return (bp); 703 } 704 bp = bp->b_hash.le_next; 705 } 706 splx(s); 707 708 return (0); 709} 710 711/* 712 * Returns true if no I/O is needed to access the 713 * associated VM object. This is like incore except 714 * it also hunts around in the VM system for the data. 715 */ 716 717int 718inmem(struct vnode * vp, daddr_t blkno) 719{ 720 vm_object_t obj; 721 vm_offset_t off, toff, tinc; 722 vm_page_t m; 723 724 if (incore(vp, blkno)) 725 return 1; 726 if (vp->v_mount == 0) 727 return 0; 728 if ((vp->v_object == 0) || (vp->v_flag & VVMIO) == 0) 729 return 0; 730 731 obj = vp->v_object; 732 tinc = PAGE_SIZE; 733 if (tinc > vp->v_mount->mnt_stat.f_iosize) 734 tinc = vp->v_mount->mnt_stat.f_iosize; 735 off = blkno * vp->v_mount->mnt_stat.f_iosize; 736 737 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 738 int mask; 739 740 m = vm_page_lookup(obj, trunc_page(toff + off)); 741 if (!m) 742 return 0; 743 if (vm_page_is_valid(m, toff + off, tinc) == 0) 744 return 0; 745 } 746 return 1; 747} 748 749/* 750 * now we set the dirty range for the buffer -- 751 * for NFS -- if the file is mapped and pages have 752 * been written to, let it know. We want the 753 * entire range of the buffer to be marked dirty if 754 * any of the pages have been written to for consistancy 755 * with the b_validoff, b_validend set in the nfs write 756 * code, and used by the nfs read code. 757 */ 758static void 759vfs_setdirty(struct buf *bp) { 760 int i; 761 vm_object_t object; 762 vm_offset_t boffset, offset; 763 /* 764 * We qualify the scan for modified pages on whether the 765 * object has been flushed yet. The OBJ_WRITEABLE flag 766 * is not cleared simply by protecting pages off. 767 */ 768 if ((bp->b_flags & B_VMIO) && 769 ((object = bp->b_pages[0]->object)->flags & OBJ_WRITEABLE)) { 770 /* 771 * test the pages to see if they have been modified directly 772 * by users through the VM system. 773 */ 774 for (i = 0; i < bp->b_npages; i++) 775 vm_page_test_dirty(bp->b_pages[i]); 776 777 /* 778 * scan forwards for the first page modified 779 */ 780 for (i = 0; i < bp->b_npages; i++) { 781 if (bp->b_pages[i]->dirty) { 782 break; 783 } 784 } 785 boffset = i * PAGE_SIZE; 786 if (boffset < bp->b_dirtyoff) { 787 bp->b_dirtyoff = boffset; 788 } 789 790 /* 791 * scan backwards for the last page modified 792 */ 793 for (i = bp->b_npages - 1; i >= 0; --i) { 794 if (bp->b_pages[i]->dirty) { 795 break; 796 } 797 } 798 boffset = (i + 1) * PAGE_SIZE; 799 offset = boffset + bp->b_pages[0]->offset; 800 if (offset >= object->size) { 801 boffset = object->size - bp->b_pages[0]->offset; 802 } 803 if (bp->b_dirtyend < boffset) { 804 bp->b_dirtyend = boffset; 805 } 806 } 807} 808 809/* 810 * Get a block given a specified block and offset into a file/device. 811 */ 812struct buf * 813getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo) 814{ 815 struct buf *bp; 816 int s; 817 struct bufhashhdr *bh; 818 vm_offset_t off; 819 int nleft; 820 821 s = splbio(); 822loop: 823 if (bp = incore(vp, blkno)) { 824 if (bp->b_flags & B_BUSY) { 825 bp->b_flags |= B_WANTED; 826 if (!tsleep((caddr_t) bp, PRIBIO | slpflag, "getblk", slptimeo)) 827 goto loop; 828 829 splx(s); 830 return (struct buf *) NULL; 831 } 832 bp->b_flags |= B_BUSY | B_CACHE; 833 bremfree(bp); 834 /* 835 * check for size inconsistancies 836 */ 837 if (bp->b_bcount != size) { 838 allocbuf(bp, size); 839 } 840 splx(s); 841 return (bp); 842 } else { 843 vm_object_t obj; 844 int doingvmio; 845 846 if ((obj = vp->v_object) && (vp->v_flag & VVMIO)) { 847 doingvmio = 1; 848 } else { 849 doingvmio = 0; 850 } 851 if ((bp = getnewbuf(slpflag, slptimeo, doingvmio)) == 0) { 852 if (slpflag || slptimeo) 853 return NULL; 854 goto loop; 855 } 856 857 /* 858 * This code is used to make sure that a buffer is not 859 * created while the getnewbuf routine is blocked. 860 * Normally the vnode is locked so this isn't a problem. 861 * VBLK type I/O requests, however, don't lock the vnode. 862 * VOP_ISLOCKED would be much better but is also much 863 * slower. 864 */ 865 if ((vp->v_type == VBLK) && incore(vp, blkno)) { 866 bp->b_flags |= B_INVAL; 867 brelse(bp); 868 goto loop; 869 } 870 871 /* 872 * Insert the buffer into the hash, so that it can 873 * be found by incore. 874 */ 875 bp->b_blkno = bp->b_lblkno = blkno; 876 bgetvp(vp, bp); 877 LIST_REMOVE(bp, b_hash); 878 bh = BUFHASH(vp, blkno); 879 LIST_INSERT_HEAD(bh, bp, b_hash); 880 881 if (doingvmio) { 882 bp->b_flags |= (B_VMIO | B_CACHE); 883#if defined(VFS_BIO_DEBUG) 884 if (vp->v_type != VREG) 885 printf("getblk: vmioing file type %d???\n", vp->v_type); 886#endif 887 } else { 888 bp->b_flags &= ~B_VMIO; 889 } 890 splx(s); 891 892 allocbuf(bp, size); 893 return (bp); 894 } 895} 896 897/* 898 * Get an empty, disassociated buffer of given size. 899 */ 900struct buf * 901geteblk(int size) 902{ 903 struct buf *bp; 904 905 while ((bp = getnewbuf(0, 0, 0)) == 0); 906 allocbuf(bp, size); 907 bp->b_flags |= B_INVAL; 908 return (bp); 909} 910 911/* 912 * This code constitutes the buffer memory from either anonymous system 913 * memory (in the case of non-VMIO operations) or from an associated 914 * VM object (in the case of VMIO operations). 915 * 916 * Note that this code is tricky, and has many complications to resolve 917 * deadlock or inconsistant data situations. Tread lightly!!! 918 * 919 * Modify the length of a buffer's underlying buffer storage without 920 * destroying information (unless, of course the buffer is shrinking). 921 */ 922int 923allocbuf(struct buf * bp, int size) 924{ 925 926 int s; 927 int newbsize, mbsize; 928 int i; 929 930 if ((bp->b_flags & B_VMIO) == 0) { 931 /* 932 * Just get anonymous memory from the kernel 933 */ 934 mbsize = ((size + DEV_BSIZE - 1) / DEV_BSIZE) * DEV_BSIZE; 935 newbsize = round_page(size); 936 937 if (newbsize == bp->b_bufsize) { 938 bp->b_bcount = size; 939 return 1; 940 } else if (newbsize < bp->b_bufsize) { 941 vm_hold_free_pages( 942 bp, 943 (vm_offset_t) bp->b_data + newbsize, 944 (vm_offset_t) bp->b_data + bp->b_bufsize); 945 bufspace -= (bp->b_bufsize - newbsize); 946 } else if (newbsize > bp->b_bufsize) { 947 vm_hold_load_pages( 948 bp, 949 (vm_offset_t) bp->b_data + bp->b_bufsize, 950 (vm_offset_t) bp->b_data + newbsize); 951 bufspace += (newbsize - bp->b_bufsize); 952 } 953 } else { 954 vm_page_t m; 955 int desiredpages; 956 957 newbsize = ((size + DEV_BSIZE - 1) / DEV_BSIZE) * DEV_BSIZE; 958 desiredpages = round_page(newbsize) / PAGE_SIZE; 959 960 if (newbsize == bp->b_bufsize) { 961 bp->b_bcount = size; 962 return 1; 963 } else if (newbsize < bp->b_bufsize) { 964 if (desiredpages < bp->b_npages) { 965 pmap_qremove((vm_offset_t) trunc_page(bp->b_data) + 966 desiredpages * PAGE_SIZE, (bp->b_npages - desiredpages)); 967 for (i = desiredpages; i < bp->b_npages; i++) { 968 m = bp->b_pages[i]; 969 s = splhigh(); 970 while ((m->flags & PG_BUSY) || (m->busy != 0)) { 971 m->flags |= PG_WANTED; 972 tsleep(m, PVM, "biodep", 0); 973 } 974 splx(s); 975 976 if (m->bmapped == 0) { 977 printf("allocbuf: bmapped is zero for page %d\n", i); 978 panic("allocbuf: error"); 979 } 980 --m->bmapped; 981 if (m->bmapped == 0) { 982 vm_page_protect(m, VM_PROT_NONE); 983 vm_page_free(m); 984 } 985 bp->b_pages[i] = NULL; 986 } 987 bp->b_npages = desiredpages; 988 bufspace -= (bp->b_bufsize - newbsize); 989 } 990 } else { 991 vm_object_t obj; 992 vm_offset_t tinc, off, toff, objoff; 993 int pageindex, curbpnpages; 994 struct vnode *vp; 995 int bsize; 996 997 vp = bp->b_vp; 998 bsize = vp->v_mount->mnt_stat.f_iosize; 999 1000 if (bp->b_npages < desiredpages) { 1001 obj = vp->v_object; 1002 tinc = PAGE_SIZE; 1003 if (tinc > bsize) 1004 tinc = bsize; 1005 off = bp->b_lblkno * bsize; 1006 curbpnpages = bp->b_npages; 1007 doretry: 1008 bp->b_flags |= B_CACHE; 1009 for (toff = 0; toff < newbsize; toff += tinc) { 1010 int mask; 1011 int bytesinpage; 1012 1013 pageindex = toff / PAGE_SIZE; 1014 objoff = trunc_page(toff + off); 1015 if (pageindex < curbpnpages) { 1016 int pb; 1017 1018 m = bp->b_pages[pageindex]; 1019 if (m->offset != objoff) 1020 panic("allocbuf: page changed offset??!!!?"); 1021 bytesinpage = tinc; 1022 if (tinc > (newbsize - toff)) 1023 bytesinpage = newbsize - toff; 1024 if (!vm_page_is_valid(m, toff + off, bytesinpage)) { 1025 bp->b_flags &= ~B_CACHE; 1026 } 1027 if ((m->flags & PG_ACTIVE) == 0) { 1028 vm_page_activate(m); 1029 m->act_count = 0; 1030 } 1031 continue; 1032 } 1033 m = vm_page_lookup(obj, objoff); 1034 if (!m) { 1035 m = vm_page_alloc(obj, objoff, VM_ALLOC_NORMAL); 1036 if (!m) { 1037 int j; 1038 1039 for (j = bp->b_npages; j < pageindex; j++) { 1040 PAGE_WAKEUP(bp->b_pages[j]); 1041 } 1042 VM_WAIT; 1043 curbpnpages = bp->b_npages; 1044 goto doretry; 1045 } 1046 vm_page_activate(m); 1047 m->act_count = 0; 1048 m->valid = 0; 1049 } else if (m->flags & PG_BUSY) { 1050 int j; 1051 1052 for (j = bp->b_npages; j < pageindex; j++) { 1053 PAGE_WAKEUP(bp->b_pages[j]); 1054 } 1055 1056 s = splbio(); 1057 m->flags |= PG_WANTED; 1058 tsleep(m, PRIBIO, "pgtblk", 0); 1059 splx(s); 1060 1061 curbpnpages = bp->b_npages; 1062 goto doretry; 1063 } else { 1064 int pb; 1065 if ((curproc != pageproc) && 1066 (m->flags & PG_CACHE) && 1067 (cnt.v_free_count + cnt.v_cache_count) < cnt.v_free_min) { 1068 pagedaemon_wakeup(); 1069 } 1070 bytesinpage = tinc; 1071 if (tinc > (newbsize - toff)) 1072 bytesinpage = newbsize - toff; 1073 if (!vm_page_is_valid(m, toff + off, bytesinpage)) { 1074 bp->b_flags &= ~B_CACHE; 1075 } 1076 if ((m->flags & PG_ACTIVE) == 0) { 1077 vm_page_activate(m); 1078 m->act_count = 0; 1079 } 1080 m->flags |= PG_BUSY; 1081 } 1082 bp->b_pages[pageindex] = m; 1083 curbpnpages = pageindex + 1; 1084 } 1085 if (bsize >= PAGE_SIZE) { 1086 for (i = bp->b_npages; i < curbpnpages; i++) { 1087 m = bp->b_pages[i]; 1088 if (m->valid == 0) { 1089 bp->b_flags &= ~B_CACHE; 1090 } 1091 m->bmapped++; 1092 PAGE_WAKEUP(m); 1093 } 1094 } else { 1095 if (!vm_page_is_valid(bp->b_pages[0], off, bsize)) 1096 bp->b_flags &= ~B_CACHE; 1097 bp->b_pages[0]->bmapped++; 1098 PAGE_WAKEUP(bp->b_pages[0]); 1099 } 1100 bp->b_npages = curbpnpages; 1101 bp->b_data = buffers_kva + (bp - buf) * MAXBSIZE; 1102 pmap_qenter((vm_offset_t) bp->b_data, bp->b_pages, bp->b_npages); 1103 bp->b_data += off % PAGE_SIZE; 1104 } 1105 bufspace += (newbsize - bp->b_bufsize); 1106 } 1107 } 1108 bp->b_bufsize = newbsize; 1109 bp->b_bcount = size; 1110 return 1; 1111} 1112 1113/* 1114 * Wait for buffer I/O completion, returning error status. 1115 */ 1116int 1117biowait(register struct buf * bp) 1118{ 1119 int s; 1120 1121 s = splbio(); 1122 while ((bp->b_flags & B_DONE) == 0) 1123 tsleep((caddr_t) bp, PRIBIO, "biowait", 0); 1124 splx(s); 1125 if (bp->b_flags & B_EINTR) { 1126 bp->b_flags &= ~B_EINTR; 1127 return (EINTR); 1128 } 1129 if (bp->b_flags & B_ERROR) { 1130 return (bp->b_error ? bp->b_error : EIO); 1131 } else { 1132 return (0); 1133 } 1134} 1135 1136/* 1137 * Finish I/O on a buffer, calling an optional function. 1138 * This is usually called from interrupt level, so process blocking 1139 * is not *a good idea*. 1140 */ 1141void 1142biodone(register struct buf * bp) 1143{ 1144 int s; 1145 1146 s = splbio(); 1147 if (bp->b_flags & B_DONE) { 1148 splx(s); 1149 printf("biodone: buffer already done\n"); 1150 return; 1151 } 1152 bp->b_flags |= B_DONE; 1153 1154 if ((bp->b_flags & B_READ) == 0) { 1155 struct vnode *vp = bp->b_vp; 1156 vwakeup(bp); 1157 } 1158#ifdef BOUNCE_BUFFERS 1159 if (bp->b_flags & B_BOUNCE) 1160 vm_bounce_free(bp); 1161#endif 1162 1163 /* call optional completion function if requested */ 1164 if (bp->b_flags & B_CALL) { 1165 bp->b_flags &= ~B_CALL; 1166 (*bp->b_iodone) (bp); 1167 splx(s); 1168 return; 1169 } 1170 if (bp->b_flags & B_VMIO) { 1171 int i, resid; 1172 vm_offset_t foff; 1173 vm_page_t m; 1174 vm_object_t obj; 1175 int iosize; 1176 struct vnode *vp = bp->b_vp; 1177 1178 foff = vp->v_mount->mnt_stat.f_iosize * bp->b_lblkno; 1179 obj = vp->v_object; 1180 if (!obj) { 1181 return; 1182 } 1183#if defined(VFS_BIO_DEBUG) 1184 if (obj->paging_in_progress < bp->b_npages) { 1185 printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n", 1186 obj->paging_in_progress, bp->b_npages); 1187 } 1188#endif 1189 iosize = bp->b_bufsize; 1190 for (i = 0; i < bp->b_npages; i++) { 1191 int bogusflag = 0; 1192 m = bp->b_pages[i]; 1193 if (m == bogus_page) { 1194 bogusflag = 1; 1195 m = vm_page_lookup(obj, foff); 1196 if (!m) { 1197#if defined(VFS_BIO_DEBUG) 1198 printf("biodone: page disappeared\n"); 1199#endif 1200 --obj->paging_in_progress; 1201 continue; 1202 } 1203 bp->b_pages[i] = m; 1204 pmap_qenter(trunc_page(bp->b_data), bp->b_pages, bp->b_npages); 1205 } 1206#if defined(VFS_BIO_DEBUG) 1207 if (trunc_page(foff) != m->offset) { 1208 printf("biodone: foff(%d)/m->offset(%d) mismatch\n", foff, m->offset); 1209 } 1210#endif 1211 resid = (m->offset + PAGE_SIZE) - foff; 1212 if (resid > iosize) 1213 resid = iosize; 1214 /* 1215 * In the write case, the valid and clean bits are 1216 * already changed correctly, so we only need to do this 1217 * here in the read case. 1218 */ 1219 if ((bp->b_flags & B_READ) && !bogusflag && resid > 0) { 1220 vm_page_set_valid(m, foff & (PAGE_SIZE-1), resid); 1221 vm_page_set_clean(m, foff & (PAGE_SIZE-1), resid); 1222 } 1223 1224 /* 1225 * when debugging new filesystems or buffer I/O methods, this 1226 * is the most common error that pops up. if you see this, you 1227 * have not set the page busy flag correctly!!! 1228 */ 1229 if (m->busy == 0) { 1230 printf("biodone: page busy < 0, " 1231 "off: %ld, foff: %ld, " 1232 "resid: %d, index: %d\n", 1233 m->offset, foff, resid, i); 1234 printf(" iosize: %ld, lblkno: %ld\n", 1235 bp->b_vp->v_mount->mnt_stat.f_iosize, 1236 bp->b_lblkno); 1237 printf(" valid: 0x%x, dirty: 0x%x, mapped: %d\n", 1238 m->valid, m->dirty, m->bmapped); 1239 panic("biodone: page busy < 0\n"); 1240 } 1241 --m->busy; 1242 if( (m->busy == 0) && (m->flags & PG_WANTED)) 1243 wakeup((caddr_t) m); 1244 --obj->paging_in_progress; 1245 foff += resid; 1246 iosize -= resid; 1247 } 1248 if (obj && obj->paging_in_progress == 0 && 1249 (obj->flags & OBJ_PIPWNT)) { 1250 obj->flags &= ~OBJ_PIPWNT; 1251 wakeup((caddr_t) obj); 1252 } 1253 } 1254 /* 1255 * For asynchronous completions, release the buffer now. The brelse 1256 * checks for B_WANTED and will do the wakeup there if necessary - so 1257 * no need to do a wakeup here in the async case. 1258 */ 1259 1260 if (bp->b_flags & B_ASYNC) { 1261 brelse(bp); 1262 } else { 1263 bp->b_flags &= ~B_WANTED; 1264 wakeup((caddr_t) bp); 1265 } 1266 splx(s); 1267} 1268 1269int 1270count_lock_queue() 1271{ 1272 int count; 1273 struct buf *bp; 1274 1275 count = 0; 1276 for (bp = bufqueues[QUEUE_LOCKED].tqh_first; 1277 bp != NULL; 1278 bp = bp->b_freelist.tqe_next) 1279 count++; 1280 return (count); 1281} 1282 1283int vfs_update_interval = 30; 1284 1285void 1286vfs_update() 1287{ 1288 (void) spl0(); 1289 while (1) { 1290 tsleep((caddr_t) &vfs_update_wakeup, PRIBIO, "update", 1291 hz * vfs_update_interval); 1292 vfs_update_wakeup = 0; 1293 sync(curproc, NULL, NULL); 1294 } 1295} 1296 1297/* 1298 * This routine is called in lieu of iodone in the case of 1299 * incomplete I/O. This keeps the busy status for pages 1300 * consistant. 1301 */ 1302void 1303vfs_unbusy_pages(struct buf * bp) 1304{ 1305 int i; 1306 1307 if (bp->b_flags & B_VMIO) { 1308 struct vnode *vp = bp->b_vp; 1309 vm_object_t obj = vp->v_object; 1310 vm_offset_t foff; 1311 1312 foff = vp->v_mount->mnt_stat.f_iosize * bp->b_lblkno; 1313 1314 for (i = 0; i < bp->b_npages; i++) { 1315 vm_page_t m = bp->b_pages[i]; 1316 1317 if (m == bogus_page) { 1318 m = vm_page_lookup(obj, foff); 1319 if (!m) { 1320 panic("vfs_unbusy_pages: page missing\n"); 1321 } 1322 bp->b_pages[i] = m; 1323 pmap_qenter(trunc_page(bp->b_data), bp->b_pages, bp->b_npages); 1324 } 1325 --obj->paging_in_progress; 1326 --m->busy; 1327 if( (m->busy == 0) && (m->flags & PG_WANTED)) 1328 wakeup((caddr_t) m); 1329 } 1330 if (obj->paging_in_progress == 0 && 1331 (obj->flags & OBJ_PIPWNT)) { 1332 obj->flags &= ~OBJ_PIPWNT; 1333 wakeup((caddr_t) obj); 1334 } 1335 } 1336} 1337 1338/* 1339 * This routine is called before a device strategy routine. 1340 * It is used to tell the VM system that paging I/O is in 1341 * progress, and treat the pages associated with the buffer 1342 * almost as being PG_BUSY. Also the object paging_in_progress 1343 * flag is handled to make sure that the object doesn't become 1344 * inconsistant. 1345 */ 1346void 1347vfs_busy_pages(struct buf * bp, int clear_modify) 1348{ 1349 int i; 1350 1351 if (bp->b_flags & B_VMIO) { 1352 vm_object_t obj = bp->b_vp->v_object; 1353 vm_offset_t foff = bp->b_vp->v_mount->mnt_stat.f_iosize * bp->b_lblkno; 1354 int iocount = bp->b_bufsize; 1355 1356 vfs_setdirty(bp); 1357 for (i = 0; i < bp->b_npages; i++) { 1358 vm_page_t m = bp->b_pages[i]; 1359 int resid = (m->offset + PAGE_SIZE) - foff; 1360 1361 if (resid > iocount) 1362 resid = iocount; 1363 obj->paging_in_progress++; 1364 m->busy++; 1365 if (clear_modify) { 1366 vm_page_protect(m, VM_PROT_READ); 1367 vm_page_set_valid(m, 1368 foff & (PAGE_SIZE-1), resid); 1369 vm_page_set_clean(m, 1370 foff & (PAGE_SIZE-1), resid); 1371 } else if (bp->b_bcount >= PAGE_SIZE) { 1372 if (m->valid && (bp->b_flags & B_CACHE) == 0) { 1373 bp->b_pages[i] = bogus_page; 1374 pmap_qenter(trunc_page(bp->b_data), bp->b_pages, bp->b_npages); 1375 } 1376 } 1377 foff += resid; 1378 iocount -= resid; 1379 } 1380 } 1381} 1382 1383/* 1384 * Tell the VM system that the pages associated with this buffer 1385 * are clean. This is used for delayed writes where the data is 1386 * going to go to disk eventually without additional VM intevention. 1387 */ 1388void 1389vfs_clean_pages(struct buf * bp) 1390{ 1391 int i; 1392 1393 if (bp->b_flags & B_VMIO) { 1394 vm_offset_t foff = 1395 bp->b_vp->v_mount->mnt_stat.f_iosize * bp->b_lblkno; 1396 int iocount = bp->b_bufsize; 1397 1398 for (i = 0; i < bp->b_npages; i++) { 1399 vm_page_t m = bp->b_pages[i]; 1400 int resid = (m->offset + PAGE_SIZE) - foff; 1401 1402 if (resid > iocount) 1403 resid = iocount; 1404 if (resid > 0) { 1405 vm_page_set_valid(m, 1406 foff & (PAGE_SIZE-1), resid); 1407 vm_page_set_clean(m, 1408 foff & (PAGE_SIZE-1), resid); 1409 } 1410 foff += resid; 1411 iocount -= resid; 1412 } 1413 } 1414} 1415 1416void 1417vfs_bio_clrbuf(struct buf *bp) { 1418 int i; 1419 if( bp->b_flags & B_VMIO) { 1420 if( (bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE)) { 1421 int j; 1422 if( bp->b_pages[0]->valid != VM_PAGE_BITS_ALL) { 1423 for(j=0; j < bp->b_bufsize / DEV_BSIZE;j++) { 1424 bzero(bp->b_data + j * DEV_BSIZE, DEV_BSIZE); 1425 } 1426 } 1427 bp->b_resid = 0; 1428 return; 1429 } 1430 for(i=0;i<bp->b_npages;i++) { 1431 if( bp->b_pages[i]->valid == VM_PAGE_BITS_ALL) 1432 continue; 1433 if( bp->b_pages[i]->valid == 0) { 1434 bzero(bp->b_data + i * PAGE_SIZE, PAGE_SIZE); 1435 } else { 1436 int j; 1437 for(j=0;j<PAGE_SIZE/DEV_BSIZE;j++) { 1438 if( (bp->b_pages[i]->valid & (1<<j)) == 0) 1439 bzero(bp->b_data + i * PAGE_SIZE + j * DEV_BSIZE, DEV_BSIZE); 1440 } 1441 } 1442 bp->b_pages[i]->valid = VM_PAGE_BITS_ALL; 1443 } 1444 bp->b_resid = 0; 1445 } else { 1446 clrbuf(bp); 1447 } 1448} 1449 1450/* 1451 * vm_hold_load_pages and vm_hold_unload pages get pages into 1452 * a buffers address space. The pages are anonymous and are 1453 * not associated with a file object. 1454 */ 1455void 1456vm_hold_load_pages(struct buf * bp, vm_offset_t froma, vm_offset_t toa) 1457{ 1458 vm_offset_t pg; 1459 vm_page_t p; 1460 vm_offset_t from = round_page(froma); 1461 vm_offset_t to = round_page(toa); 1462 1463 for (pg = from; pg < to; pg += PAGE_SIZE) { 1464 1465tryagain: 1466 1467 p = vm_page_alloc(kernel_object, pg - VM_MIN_KERNEL_ADDRESS, 1468 VM_ALLOC_NORMAL); 1469 if (!p) { 1470 VM_WAIT; 1471 goto tryagain; 1472 } 1473 vm_page_wire(p); 1474 pmap_kenter(pg, VM_PAGE_TO_PHYS(p)); 1475 bp->b_pages[((caddr_t) pg - bp->b_data) / PAGE_SIZE] = p; 1476 PAGE_WAKEUP(p); 1477 bp->b_npages++; 1478 } 1479} 1480 1481void 1482vm_hold_free_pages(struct buf * bp, vm_offset_t froma, vm_offset_t toa) 1483{ 1484 vm_offset_t pg; 1485 vm_page_t p; 1486 vm_offset_t from = round_page(froma); 1487 vm_offset_t to = round_page(toa); 1488 1489 for (pg = from; pg < to; pg += PAGE_SIZE) { 1490 p = bp->b_pages[((caddr_t) pg - bp->b_data) / PAGE_SIZE]; 1491 bp->b_pages[((caddr_t) pg - bp->b_data) / PAGE_SIZE] = 0; 1492 pmap_kremove(pg); 1493 vm_page_free(p); 1494 --bp->b_npages; 1495 } 1496} 1497