Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/kern/vfs_bio.c
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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 * $FreeBSD: src/sys/kern/vfs_bio.c,v 1.104.2.15 1999/09/05 08:15:37 peter 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 #include "opt_bounce.h" 36 37 #define VMIO 38 #include <sys/param.h> 39 #include <sys/systm.h> 40 #include <sys/sysproto.h> 41 #include <sys/kernel.h> 42 #include <sys/sysctl.h> 43 #include <sys/proc.h> 44 #include <sys/vnode.h> 45 #include <sys/vmmeter.h> 46 #include <vm/vm.h> 47 #include <vm/vm_param.h> 48 #include <vm/vm_prot.h> 49 #include <vm/vm_kern.h> 50 #include <vm/vm_pageout.h> 51 #include <vm/vm_page.h> 52 #include <vm/vm_object.h> 53 #include <vm/vm_extern.h> 54 #include <vm/lock.h> 55 #include <vm/vm_map.h> 56 #include <sys/buf.h> 57 #include <sys/mount.h> 58 #include <sys/malloc.h> 59 #include <sys/resourcevar.h> 60 #include <sys/proc.h> 61 62 #include <miscfs/specfs/specdev.h> 63 64 static void vfs_update __P((void)); 65 static struct proc *updateproc; 66 static struct kproc_desc up_kp = { 67 "update", 68 vfs_update, 69 &updateproc 70 }; 71 SYSINIT_KT(update, SI_SUB_KTHREAD_UPDATE, SI_ORDER_FIRST, kproc_start, &up_kp) 72 73 struct buf *buf; /* buffer header pool */ 74 struct swqueue bswlist; 75 76 int count_lock_queue __P((void)); 77 static void vm_hold_free_pages(struct buf * bp, vm_offset_t from, 78 vm_offset_t to); 79 static void vm_hold_load_pages(struct buf * bp, vm_offset_t from, 80 vm_offset_t to); 81 static void vfs_buf_set_valid(struct buf *bp, vm_ooffset_t foff, 82 vm_offset_t off, vm_offset_t size, 83 vm_page_t m); 84 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, 85 int pageno, vm_page_t m); 86 static void vfs_clean_pages(struct buf * bp); 87 static void vfs_setdirty(struct buf *bp); 88 static void vfs_vmio_release(struct buf *bp); 89 90 int needsbuffer; 91 92 /* 93 * Internal update daemon, process 3 94 * The variable vfs_update_wakeup allows for internal syncs. 95 */ 96 int vfs_update_wakeup; 97 98 99 /* 100 * buffers base kva 101 */ 102 103 /* 104 * bogus page -- for I/O to/from partially complete buffers 105 * this is a temporary solution to the problem, but it is not 106 * really that bad. it would be better to split the buffer 107 * for input in the case of buffers partially already in memory, 108 * but the code is intricate enough already. 109 */ 110 vm_page_t bogus_page; 111 static vm_offset_t bogus_offset; 112 113 static int bufspace, maxbufspace, vmiospace, maxvmiobufspace, 114 bufmallocspace, maxbufmallocspace; 115 116 static struct bufhashhdr bufhashtbl[BUFHSZ], invalhash; 117 static struct bqueues bufqueues[BUFFER_QUEUES]; 118 119 extern int vm_swap_size; 120 121 #define BUF_MAXUSE 16 122 123 /* 124 * Initialize buffer headers and related structures. 125 */ 126 void 127 bufinit() 128 { 129 struct buf *bp; 130 int i; 131 132 TAILQ_INIT(&bswlist); 133 LIST_INIT(&invalhash); 134 135 /* first, make a null hash table */ 136 for (i = 0; i < BUFHSZ; i++) 137 LIST_INIT(&bufhashtbl[i]); 138 139 /* next, make a null set of free lists */ 140 for (i = 0; i < BUFFER_QUEUES; i++) 141 TAILQ_INIT(&bufqueues[i]); 142 143 /* finally, initialize each buffer header and stick on empty q */ 144 for (i = 0; i < nbuf; i++) { 145 bp = &buf[i]; 146 bzero(bp, sizeof *bp); 147 bp->b_flags = B_INVAL; /* we're just an empty header */ 148 bp->b_dev = NODEV; 149 bp->b_rcred = NOCRED; 150 bp->b_wcred = NOCRED; 151 bp->b_qindex = QUEUE_EMPTY; 152 bp->b_vnbufs.le_next = NOLIST; 153 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 154 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 155 } 156 /* 157 * maxbufspace is currently calculated to support all filesystem blocks 158 * to be 8K. If you happen to use a 16K filesystem, the size of the buffer 159 * cache is still the same as it would be for 8K filesystems. This 160 * keeps the size of the buffer cache "in check" for big block filesystems. 161 */ 162 maxbufspace = (nbuf + 8) * DFLTBSIZE; 163 /* 164 * reserve 1/3 of the buffers for metadata (VDIR) which might not be VMIO'ed 165 */ 166 maxvmiobufspace = 2 * maxbufspace / 3; 167 /* 168 * Limit the amount of malloc memory since it is wired permanently into 169 * the kernel space. Even though this is accounted for in the buffer 170 * allocation, we don't want the malloced region to grow uncontrolled. 171 * The malloc scheme improves memory utilization significantly on average 172 * (small) directories. 173 */ 174 maxbufmallocspace = maxbufspace / 20; 175 176 bogus_offset = kmem_alloc_pageable(kernel_map, PAGE_SIZE); 177 bogus_page = vm_page_alloc(kernel_object, 178 ((bogus_offset - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 179 VM_ALLOC_NORMAL); 180 181 } 182 183 /* 184 * Free the kva allocation for a buffer 185 * Must be called only at splbio or higher, 186 * as this is the only locking for buffer_map. 187 */ 188 static void 189 bfreekva(struct buf * bp) 190 { 191 if (bp->b_kvasize == 0) 192 return; 193 194 vm_map_delete(buffer_map, 195 (vm_offset_t) bp->b_kvabase, 196 (vm_offset_t) bp->b_kvabase + bp->b_kvasize); 197 198 bp->b_kvasize = 0; 199 200 } 201 202 /* 203 * remove the buffer from the appropriate free list 204 */ 205 void 206 bremfree(struct buf * bp) 207 { 208 int s = splbio(); 209 210 if (bp->b_qindex != QUEUE_NONE) { 211 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 212 bp->b_qindex = QUEUE_NONE; 213 } else { 214 panic("bremfree: removing a buffer when not on a queue"); 215 } 216 splx(s); 217 } 218 219 /* 220 * Get a buffer with the specified data. Look in the cache first. 221 */ 222 int 223 bread(struct vnode * vp, daddr_t blkno, int size, struct ucred * cred, 224 struct buf ** bpp) 225 { 226 struct buf *bp; 227 228 bp = getblk(vp, blkno, size, 0, 0); 229 *bpp = bp; 230 231 /* if not found in cache, do some I/O */ 232 if ((bp->b_flags & B_CACHE) == 0) { 233 if (curproc != NULL) 234 curproc->p_stats->p_ru.ru_inblock++; 235 bp->b_flags |= B_READ; 236 bp->b_flags &= ~(B_DONE | B_ERROR | B_INVAL); 237 if (bp->b_rcred == NOCRED) { 238 if (cred != NOCRED) 239 crhold(cred); 240 bp->b_rcred = cred; 241 } 242 vfs_busy_pages(bp, 0); 243 VOP_STRATEGY(bp); 244 return (biowait(bp)); 245 } 246 return (0); 247 } 248 249 /* 250 * Operates like bread, but also starts asynchronous I/O on 251 * read-ahead blocks. 252 */ 253 int 254 breadn(struct vnode * vp, daddr_t blkno, int size, 255 daddr_t * rablkno, int *rabsize, 256 int cnt, struct ucred * cred, struct buf ** bpp) 257 { 258 struct buf *bp, *rabp; 259 int i; 260 int rv = 0, readwait = 0; 261 262 *bpp = bp = getblk(vp, blkno, size, 0, 0); 263 264 /* if not found in cache, do some I/O */ 265 if ((bp->b_flags & B_CACHE) == 0) { 266 if (curproc != NULL) 267 curproc->p_stats->p_ru.ru_inblock++; 268 bp->b_flags |= B_READ; 269 bp->b_flags &= ~(B_DONE | B_ERROR | B_INVAL); 270 if (bp->b_rcred == NOCRED) { 271 if (cred != NOCRED) 272 crhold(cred); 273 bp->b_rcred = cred; 274 } 275 vfs_busy_pages(bp, 0); 276 VOP_STRATEGY(bp); 277 ++readwait; 278 } 279 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 280 if (inmem(vp, *rablkno)) 281 continue; 282 rabp = getblk(vp, *rablkno, *rabsize, 0, 0); 283 284 if ((rabp->b_flags & B_CACHE) == 0) { 285 if (curproc != NULL) 286 curproc->p_stats->p_ru.ru_inblock++; 287 rabp->b_flags |= B_READ | B_ASYNC; 288 rabp->b_flags &= ~(B_DONE | B_ERROR | B_INVAL); 289 if (rabp->b_rcred == NOCRED) { 290 if (cred != NOCRED) 291 crhold(cred); 292 rabp->b_rcred = cred; 293 } 294 vfs_busy_pages(rabp, 0); 295 VOP_STRATEGY(rabp); 296 } else { 297 brelse(rabp); 298 } 299 } 300 301 if (readwait) { 302 rv = biowait(bp); 303 } 304 return (rv); 305 } 306 307 /* 308 * Write, release buffer on completion. (Done by iodone 309 * if async.) 310 */ 311 int 312 bwrite(struct buf * bp) 313 { 314 int oldflags = bp->b_flags; 315 316 if (bp->b_flags & B_INVAL) { 317 brelse(bp); 318 return (0); 319 } 320 if (!(bp->b_flags & B_BUSY)) 321 panic("bwrite: buffer is not busy???"); 322 323 bp->b_flags &= ~(B_READ | B_DONE | B_ERROR | B_DELWRI); 324 bp->b_flags |= B_WRITEINPROG; 325 326 if ((oldflags & (B_ASYNC|B_DELWRI)) == (B_ASYNC|B_DELWRI)) { 327 reassignbuf(bp, bp->b_vp); 328 } 329 330 bp->b_vp->v_numoutput++; 331 vfs_busy_pages(bp, 1); 332 if (curproc != NULL) 333 curproc->p_stats->p_ru.ru_oublock++; 334 VOP_STRATEGY(bp); 335 336 if ((oldflags & B_ASYNC) == 0) { 337 int rtval = biowait(bp); 338 339 if (oldflags & B_DELWRI) { 340 reassignbuf(bp, bp->b_vp); 341 } 342 brelse(bp); 343 return (rtval); 344 } 345 return (0); 346 } 347 348 int 349 vn_bwrite(ap) 350 struct vop_bwrite_args *ap; 351 { 352 return (bwrite(ap->a_bp)); 353 } 354 355 /* 356 * Delayed write. (Buffer is marked dirty). 357 */ 358 void 359 bdwrite(struct buf * bp) 360 { 361 362 if ((bp->b_flags & B_BUSY) == 0) { 363 panic("bdwrite: buffer is not busy"); 364 } 365 if (bp->b_flags & B_INVAL) { 366 brelse(bp); 367 return; 368 } 369 if (bp->b_flags & B_TAPE) { 370 bawrite(bp); 371 return; 372 } 373 bp->b_flags &= ~(B_READ|B_RELBUF); 374 if ((bp->b_flags & B_DELWRI) == 0) { 375 bp->b_flags |= B_DONE | B_DELWRI; 376 reassignbuf(bp, bp->b_vp); 377 } 378 379 /* 380 * This bmap keeps the system from needing to do the bmap later, 381 * perhaps when the system is attempting to do a sync. Since it 382 * is likely that the indirect block -- or whatever other datastructure 383 * that the filesystem needs is still in memory now, it is a good 384 * thing to do this. Note also, that if the pageout daemon is 385 * requesting a sync -- there might not be enough memory to do 386 * the bmap then... So, this is important to do. 387 */ 388 if( bp->b_lblkno == bp->b_blkno) { 389 VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 390 } 391 392 /* 393 * Set the *dirty* buffer range based upon the VM system dirty pages. 394 */ 395 vfs_setdirty(bp); 396 397 /* 398 * We need to do this here to satisfy the vnode_pager and the 399 * pageout daemon, so that it thinks that the pages have been 400 * "cleaned". Note that since the pages are in a delayed write 401 * buffer -- the VFS layer "will" see that the pages get written 402 * out on the next sync, or perhaps the cluster will be completed. 403 */ 404 vfs_clean_pages(bp); 405 bqrelse(bp); 406 return; 407 } 408 409 /* 410 * Asynchronous write. 411 * Start output on a buffer, but do not wait for it to complete. 412 * The buffer is released when the output completes. 413 */ 414 void 415 bawrite(struct buf * bp) 416 { 417 bp->b_flags |= B_ASYNC; 418 (void) VOP_BWRITE(bp); 419 } 420 421 /* 422 * Ordered write. 423 * Start output on a buffer, but only wait for it to complete if the 424 * output device cannot guarantee ordering in some other way. Devices 425 * that can perform asynchronous ordered writes will set the B_ASYNC 426 * flag in their strategy routine. 427 * The buffer is released when the output completes. 428 */ 429 int 430 bowrite(struct buf * bp) 431 { 432 bp->b_flags |= B_ORDERED; 433 return (VOP_BWRITE(bp)); 434 } 435 436 /* 437 * Release a buffer. 438 */ 439 void 440 brelse(struct buf * bp) 441 { 442 int s; 443 444 if (bp->b_flags & B_CLUSTER) { 445 relpbuf(bp); 446 return; 447 } 448 /* anyone need a "free" block? */ 449 s = splbio(); 450 451 /* anyone need this block? */ 452 if (bp->b_flags & B_WANTED) { 453 bp->b_flags &= ~(B_WANTED | B_AGE); 454 wakeup(bp); 455 } 456 457 if (bp->b_flags & B_LOCKED) 458 bp->b_flags &= ~B_ERROR; 459 460 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR)) || 461 (bp->b_bufsize <= 0)) { 462 bp->b_flags |= B_INVAL; 463 bp->b_flags &= ~(B_DELWRI | B_CACHE); 464 if (((bp->b_flags & B_VMIO) == 0) && bp->b_vp) { 465 if (bp->b_bufsize) 466 allocbuf(bp, 0); 467 brelvp(bp); 468 } 469 } 470 471 /* 472 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 473 * is called with B_DELWRI set, the underlying pages may wind up 474 * getting freed causing a previous write (bdwrite()) to get 'lost' 475 * because pages associated with a B_DELWRI bp are marked clean. 476 * 477 * We still allow the B_INVAL case to call vfs_vmio_release(), even 478 * if B_DELWRI is set. 479 */ 480 481 if (bp->b_flags & B_DELWRI) 482 bp->b_flags &= ~B_RELBUF; 483 484 /* 485 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 486 * constituted, so the B_INVAL flag is used to *invalidate* the buffer, 487 * but the VM object is kept around. The B_NOCACHE flag is used to 488 * invalidate the pages in the VM object. 489 * 490 * If the buffer is a partially filled NFS buffer, keep it 491 * since invalidating it now will lose informatio. The valid 492 * flags in the vm_pages have only DEV_BSIZE resolution but 493 * the b_validoff, b_validend fields have byte resolution. 494 * This can avoid unnecessary re-reads of the buffer. 495 */ 496 if ((bp->b_flags & B_VMIO) 497 && (bp->b_vp->v_tag != VT_NFS 498 || bp->b_vp->v_type == VBLK 499 || (bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR)) 500 || bp->b_validend == 0 501 || (bp->b_validoff == 0 502 && bp->b_validend == bp->b_bufsize))) { 503 vm_ooffset_t foff; 504 vm_object_t obj; 505 int i, resid; 506 vm_page_t m; 507 struct vnode *vp; 508 int iototal = bp->b_bufsize; 509 510 vp = bp->b_vp; 511 if (!vp) 512 panic("brelse: missing vp"); 513 514 if (bp->b_npages) { 515 vm_pindex_t poff; 516 obj = (vm_object_t) vp->v_object; 517 if (vp->v_type == VBLK) 518 foff = ((vm_ooffset_t) bp->b_lblkno) << DEV_BSHIFT; 519 else 520 foff = (vm_ooffset_t) vp->v_mount->mnt_stat.f_iosize * bp->b_lblkno; 521 poff = OFF_TO_IDX(foff); 522 for (i = 0; i < bp->b_npages; i++) { 523 m = bp->b_pages[i]; 524 if (m == bogus_page) { 525 m = vm_page_lookup(obj, poff + i); 526 if (!m) { 527 panic("brelse: page missing\n"); 528 } 529 bp->b_pages[i] = m; 530 pmap_qenter(trunc_page(bp->b_data), 531 bp->b_pages, bp->b_npages); 532 } 533 resid = IDX_TO_OFF(m->pindex+1) - foff; 534 if (resid > iototal) 535 resid = iototal; 536 if (resid > 0) { 537 /* 538 * Don't invalidate the page if the local machine has already 539 * modified it. This is the lesser of two evils, and should 540 * be fixed. 541 */ 542 if (bp->b_flags & (B_NOCACHE | B_ERROR)) { 543 vm_page_test_dirty(m); 544 if (m->dirty == 0) { 545 vm_page_set_invalid(m, (vm_offset_t) foff, resid); 546 if (m->valid == 0) 547 vm_page_protect(m, VM_PROT_NONE); 548 } 549 } 550 if (resid >= PAGE_SIZE) { 551 if ((m->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) { 552 bp->b_flags |= B_INVAL; 553 } 554 } else { 555 if (!vm_page_is_valid(m, 556 (((vm_offset_t) bp->b_data) & PAGE_MASK), resid)) { 557 bp->b_flags |= B_INVAL; 558 } 559 } 560 } 561 foff += resid; 562 iototal -= resid; 563 } 564 } 565 if (bp->b_flags & (B_INVAL | B_RELBUF)) 566 vfs_vmio_release(bp); 567 } 568 if (bp->b_qindex != QUEUE_NONE) 569 panic("brelse: free buffer onto another queue???"); 570 571 /* enqueue */ 572 /* buffers with no memory */ 573 if (bp->b_bufsize == 0) { 574 bp->b_qindex = QUEUE_EMPTY; 575 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 576 LIST_REMOVE(bp, b_hash); 577 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 578 bp->b_dev = NODEV; 579 /* 580 * Get rid of the kva allocation *now* 581 */ 582 bfreekva(bp); 583 if (needsbuffer) { 584 wakeup(&needsbuffer); 585 needsbuffer=0; 586 } 587 /* buffers with junk contents */ 588 } else if (bp->b_flags & (B_ERROR | B_INVAL | B_NOCACHE | B_RELBUF)) { 589 bp->b_qindex = QUEUE_AGE; 590 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_AGE], bp, b_freelist); 591 LIST_REMOVE(bp, b_hash); 592 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 593 bp->b_dev = NODEV; 594 if (needsbuffer) { 595 wakeup(&needsbuffer); 596 needsbuffer=0; 597 } 598 /* buffers that are locked */ 599 } else if (bp->b_flags & B_LOCKED) { 600 bp->b_qindex = QUEUE_LOCKED; 601 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LOCKED], bp, b_freelist); 602 /* buffers with stale but valid contents */ 603 } else if (bp->b_flags & B_AGE) { 604 bp->b_qindex = QUEUE_AGE; 605 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_AGE], bp, b_freelist); 606 if (needsbuffer) { 607 wakeup(&needsbuffer); 608 needsbuffer=0; 609 } 610 /* buffers with valid and quite potentially reuseable contents */ 611 } else { 612 bp->b_qindex = QUEUE_LRU; 613 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LRU], bp, b_freelist); 614 if (needsbuffer) { 615 wakeup(&needsbuffer); 616 needsbuffer=0; 617 } 618 } 619 620 /* unlock */ 621 bp->b_flags &= ~(B_ORDERED | B_WANTED | B_BUSY | 622 B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 623 splx(s); 624 } 625 626 /* 627 * Release a buffer. 628 */ 629 void 630 bqrelse(struct buf * bp) 631 { 632 int s; 633 634 s = splbio(); 635 636 637 /* anyone need this block? */ 638 if (bp->b_flags & B_WANTED) { 639 bp->b_flags &= ~(B_WANTED | B_AGE); 640 wakeup(bp); 641 } 642 643 if (bp->b_qindex != QUEUE_NONE) 644 panic("bqrelse: free buffer onto another queue???"); 645 646 if (bp->b_flags & B_LOCKED) { 647 bp->b_flags &= ~B_ERROR; 648 bp->b_qindex = QUEUE_LOCKED; 649 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LOCKED], bp, b_freelist); 650 /* buffers with stale but valid contents */ 651 } else { 652 bp->b_qindex = QUEUE_LRU; 653 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LRU], bp, b_freelist); 654 if (needsbuffer) { 655 wakeup(&needsbuffer); 656 needsbuffer=0; 657 } 658 } 659 660 /* unlock */ 661 bp->b_flags &= ~(B_ORDERED | B_WANTED | B_BUSY | 662 B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 663 splx(s); 664 } 665 666 static void 667 vfs_vmio_release(bp) 668 struct buf *bp; 669 { 670 int i; 671 vm_page_t m; 672 673 for (i = 0; i < bp->b_npages; i++) { 674 m = bp->b_pages[i]; 675 bp->b_pages[i] = NULL; 676 vm_page_unwire(m); 677 /* 678 * We don't mess with busy pages, it is 679 * the responsibility of the process that 680 * busied the pages to deal with them. 681 */ 682 if ((m->flags & PG_BUSY) || (m->busy != 0)) 683 continue; 684 685 if (m->wire_count == 0) { 686 687 if (m->flags & PG_WANTED) { 688 m->flags &= ~PG_WANTED; 689 wakeup(m); 690 } 691 692 /* 693 * If this is an async free -- we cannot place 694 * pages onto the cache queue, so our policy for 695 * such buffers is to avoid the cache queue, and 696 * only modify the active queue or free queue. 697 */ 698 if ((bp->b_flags & B_ASYNC) == 0) { 699 700 /* 701 * In the case of sync buffer frees, we can do pretty much 702 * anything to any of the memory queues. Specifically, 703 * the cache queue is free to be modified. 704 */ 705 if (m->valid) { 706 if(m->dirty == 0) 707 vm_page_test_dirty(m); 708 /* 709 * this keeps pressure off of the process memory 710 */ 711 if ((vm_swap_size == 0) || 712 (cnt.v_free_count < cnt.v_free_min)) { 713 if ((m->dirty == 0) && 714 (m->hold_count == 0)) 715 vm_page_cache(m); 716 else 717 vm_page_deactivate(m); 718 } 719 } else if (m->hold_count == 0) { 720 vm_page_protect(m, VM_PROT_NONE); 721 vm_page_free(m); 722 } 723 } else { 724 /* 725 * If async, then at least we clear the 726 * act_count. 727 */ 728 m->act_count = 0; 729 } 730 } 731 } 732 bufspace -= bp->b_bufsize; 733 vmiospace -= bp->b_bufsize; 734 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages); 735 bp->b_npages = 0; 736 bp->b_bufsize = 0; 737 bp->b_flags &= ~B_VMIO; 738 if (bp->b_vp) 739 brelvp(bp); 740 } 741 742 /* 743 * Check to see if a block is currently memory resident. 744 */ 745 struct buf * 746 gbincore(struct vnode * vp, daddr_t blkno) 747 { 748 struct buf *bp; 749 struct bufhashhdr *bh; 750 751 bh = BUFHASH(vp, blkno); 752 bp = bh->lh_first; 753 754 /* Search hash chain */ 755 while (bp != NULL) { 756 /* hit */ 757 if (bp->b_vp == vp && bp->b_lblkno == blkno && 758 (bp->b_flags & B_INVAL) == 0) { 759 break; 760 } 761 bp = bp->b_hash.le_next; 762 } 763 return (bp); 764 } 765 766 /* 767 * this routine implements clustered async writes for 768 * clearing out B_DELWRI buffers... This is much better 769 * than the old way of writing only one buffer at a time. 770 */ 771 int 772 vfs_bio_awrite(struct buf * bp) 773 { 774 int i; 775 daddr_t lblkno = bp->b_lblkno; 776 struct vnode *vp = bp->b_vp; 777 int s; 778 int ncl; 779 struct buf *bpa; 780 int nwritten; 781 782 s = splbio(); 783 /* 784 * right now we support clustered writing only to regular files 785 */ 786 if ((vp->v_type == VREG) && 787 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 788 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 789 int size; 790 int maxcl; 791 792 size = vp->v_mount->mnt_stat.f_iosize; 793 maxcl = MAXPHYS / size; 794 795 for (i = 1; i < maxcl; i++) { 796 if ((bpa = gbincore(vp, lblkno + i)) && 797 ((bpa->b_flags & (B_BUSY | B_DELWRI | B_CLUSTEROK | B_INVAL)) == 798 (B_DELWRI | B_CLUSTEROK)) && 799 (bpa->b_bufsize == size)) { 800 if ((bpa->b_blkno == bpa->b_lblkno) || 801 (bpa->b_blkno != bp->b_blkno + ((i * size) >> DEV_BSHIFT))) 802 break; 803 } else { 804 break; 805 } 806 } 807 ncl = i; 808 /* 809 * this is a possible cluster write 810 */ 811 if (ncl != 1) { 812 nwritten = cluster_wbuild(vp, size, lblkno, ncl); 813 splx(s); 814 return nwritten; 815 } 816 } 817 bremfree(bp); 818 splx(s); 819 /* 820 * default (old) behavior, writing out only one block 821 */ 822 bp->b_flags |= B_BUSY | B_ASYNC; 823 nwritten = bp->b_bufsize; 824 (void) VOP_BWRITE(bp); 825 return nwritten; 826 } 827 828 829 /* 830 * Find a buffer header which is available for use. 831 */ 832 static struct buf * 833 getnewbuf(int slpflag, int slptimeo, int size, int maxsize) 834 { 835 struct buf *bp; 836 int nbyteswritten = 0; 837 vm_offset_t addr; 838 839 start: 840 if (bufspace >= maxbufspace) 841 goto trytofreespace; 842 843 /* can we constitute a new buffer? */ 844 if ((bp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]))) { 845 if (bp->b_qindex != QUEUE_EMPTY) 846 panic("getnewbuf: inconsistent EMPTY queue, qindex=%d", 847 bp->b_qindex); 848 bp->b_flags |= B_BUSY; 849 bremfree(bp); 850 goto fillbuf; 851 } 852 trytofreespace: 853 /* 854 * We keep the file I/O from hogging metadata I/O 855 * This is desirable because file data is cached in the 856 * VM/Buffer cache even if a buffer is freed. 857 */ 858 if ((bp = TAILQ_FIRST(&bufqueues[QUEUE_AGE]))) { 859 if (bp->b_qindex != QUEUE_AGE) 860 panic("getnewbuf: inconsistent AGE queue, qindex=%d", 861 bp->b_qindex); 862 } else if ((bp = TAILQ_FIRST(&bufqueues[QUEUE_LRU]))) { 863 if (bp->b_qindex != QUEUE_LRU) 864 panic("getnewbuf: inconsistent LRU queue, qindex=%d", 865 bp->b_qindex); 866 } 867 if (!bp) { 868 /* wait for a free buffer of any kind */ 869 needsbuffer = 1; 870 do 871 tsleep(&needsbuffer, (PRIBIO + 1) | slpflag, "newbuf", 872 slptimeo); 873 while (needsbuffer); 874 return (0); 875 } 876 877 #if defined(DIAGNOSTIC) 878 if (bp->b_flags & B_BUSY) { 879 panic("getnewbuf: busy buffer on free list\n"); 880 } 881 #endif 882 883 /* 884 * We are fairly aggressive about freeing VMIO buffers, but since 885 * the buffering is intact without buffer headers, there is not 886 * much loss. We gain by maintaining non-VMIOed metadata in buffers. 887 */ 888 if ((bp->b_qindex == QUEUE_LRU) && (bp->b_usecount > 0)) { 889 if ((bp->b_flags & B_VMIO) == 0 || 890 (vmiospace < maxvmiobufspace)) { 891 --bp->b_usecount; 892 TAILQ_REMOVE(&bufqueues[QUEUE_LRU], bp, b_freelist); 893 if (TAILQ_FIRST(&bufqueues[QUEUE_LRU]) != NULL) { 894 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LRU], bp, b_freelist); 895 goto start; 896 } 897 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LRU], bp, b_freelist); 898 } 899 } 900 901 /* if we are a delayed write, convert to an async write */ 902 if ((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI) { 903 nbyteswritten += vfs_bio_awrite(bp); 904 if (!slpflag && !slptimeo) { 905 return (0); 906 } 907 goto start; 908 } 909 910 if (bp->b_flags & B_WANTED) { 911 bp->b_flags &= ~B_WANTED; 912 wakeup(bp); 913 } 914 bremfree(bp); 915 bp->b_flags |= B_BUSY; 916 917 if (bp->b_flags & B_VMIO) { 918 bp->b_flags &= ~B_ASYNC; 919 vfs_vmio_release(bp); 920 } 921 922 if (bp->b_vp) 923 brelvp(bp); 924 925 fillbuf: 926 /* we are not free, nor do we contain interesting data */ 927 if (bp->b_rcred != NOCRED) { 928 crfree(bp->b_rcred); 929 bp->b_rcred = NOCRED; 930 } 931 if (bp->b_wcred != NOCRED) { 932 crfree(bp->b_wcred); 933 bp->b_wcred = NOCRED; 934 } 935 936 LIST_REMOVE(bp, b_hash); 937 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 938 if (bp->b_bufsize) { 939 allocbuf(bp, 0); 940 } 941 bp->b_flags = B_BUSY; 942 bp->b_dev = NODEV; 943 bp->b_vp = NULL; 944 bp->b_blkno = bp->b_lblkno = 0; 945 bp->b_iodone = 0; 946 bp->b_error = 0; 947 bp->b_resid = 0; 948 bp->b_bcount = 0; 949 bp->b_npages = 0; 950 bp->b_dirtyoff = bp->b_dirtyend = 0; 951 bp->b_validoff = bp->b_validend = 0; 952 bp->b_usecount = 4; 953 954 maxsize = (maxsize + PAGE_MASK) & ~PAGE_MASK; 955 956 /* 957 * we assume that buffer_map is not at address 0 958 */ 959 addr = 0; 960 if (maxsize != bp->b_kvasize) { 961 bfreekva(bp); 962 963 /* 964 * See if we have buffer kva space 965 */ 966 if (vm_map_findspace(buffer_map, 967 vm_map_min(buffer_map), maxsize, &addr)) { 968 bp->b_flags |= B_INVAL; 969 brelse(bp); 970 goto trytofreespace; 971 } 972 } 973 974 /* 975 * See if we are below are allocated minimum 976 */ 977 if (bufspace >= (maxbufspace + nbyteswritten)) { 978 bp->b_flags |= B_INVAL; 979 brelse(bp); 980 goto trytofreespace; 981 } 982 983 /* 984 * create a map entry for the buffer -- in essence 985 * reserving the kva space. 986 */ 987 if (addr) { 988 vm_map_insert(buffer_map, NULL, 0, 989 addr, addr + maxsize, 990 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT); 991 992 bp->b_kvabase = (caddr_t) addr; 993 bp->b_kvasize = maxsize; 994 } 995 bp->b_data = bp->b_kvabase; 996 997 return (bp); 998 } 999 1000 /* 1001 * Check to see if a block is currently memory resident. 1002 */ 1003 struct buf * 1004 incore(struct vnode * vp, daddr_t blkno) 1005 { 1006 struct buf *bp; 1007 1008 int s = splbio(); 1009 bp = gbincore(vp, blkno); 1010 splx(s); 1011 return (bp); 1012 } 1013 1014 /* 1015 * Returns true if no I/O is needed to access the 1016 * associated VM object. This is like incore except 1017 * it also hunts around in the VM system for the data. 1018 */ 1019 1020 int 1021 inmem(struct vnode * vp, daddr_t blkno) 1022 { 1023 vm_object_t obj; 1024 vm_offset_t toff, tinc; 1025 vm_page_t m; 1026 vm_ooffset_t off; 1027 1028 if (incore(vp, blkno)) 1029 return 1; 1030 if (vp->v_mount == NULL) 1031 return 0; 1032 if ((vp->v_object == NULL) || (vp->v_flag & VVMIO) == 0) 1033 return 0; 1034 1035 obj = vp->v_object; 1036 tinc = PAGE_SIZE; 1037 if (tinc > vp->v_mount->mnt_stat.f_iosize) 1038 tinc = vp->v_mount->mnt_stat.f_iosize; 1039 off = blkno * vp->v_mount->mnt_stat.f_iosize; 1040 1041 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 1042 1043 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 1044 if (!m) 1045 return 0; 1046 if (vm_page_is_valid(m, (vm_offset_t) (toff + off), tinc) == 0) 1047 return 0; 1048 } 1049 return 1; 1050 } 1051 1052 /* 1053 * now we set the dirty range for the buffer -- 1054 * for NFS -- if the file is mapped and pages have 1055 * been written to, let it know. We want the 1056 * entire range of the buffer to be marked dirty if 1057 * any of the pages have been written to for consistancy 1058 * with the b_validoff, b_validend set in the nfs write 1059 * code, and used by the nfs read code. 1060 */ 1061 static void 1062 vfs_setdirty(struct buf *bp) { 1063 int i; 1064 vm_object_t object; 1065 vm_offset_t boffset, offset; 1066 /* 1067 * We qualify the scan for modified pages on whether the 1068 * object has been flushed yet. The OBJ_WRITEABLE flag 1069 * is not cleared simply by protecting pages off. 1070 */ 1071 if ((bp->b_flags & B_VMIO) && 1072 ((object = bp->b_pages[0]->object)->flags & (OBJ_WRITEABLE|OBJ_CLEANING))) { 1073 /* 1074 * test the pages to see if they have been modified directly 1075 * by users through the VM system. 1076 */ 1077 for (i = 0; i < bp->b_npages; i++) 1078 vm_page_test_dirty(bp->b_pages[i]); 1079 1080 /* 1081 * scan forwards for the first page modified 1082 */ 1083 for (i = 0; i < bp->b_npages; i++) { 1084 if (bp->b_pages[i]->dirty) { 1085 break; 1086 } 1087 } 1088 boffset = (i << PAGE_SHIFT); 1089 if (boffset < bp->b_dirtyoff) { 1090 bp->b_dirtyoff = boffset; 1091 } 1092 1093 /* 1094 * scan backwards for the last page modified 1095 */ 1096 for (i = bp->b_npages - 1; i >= 0; --i) { 1097 if (bp->b_pages[i]->dirty) { 1098 break; 1099 } 1100 } 1101 boffset = (i + 1); 1102 offset = boffset + bp->b_pages[0]->pindex; 1103 if (offset >= object->size) 1104 boffset = object->size - bp->b_pages[0]->pindex; 1105 if (bp->b_dirtyend < (boffset << PAGE_SHIFT)) 1106 bp->b_dirtyend = (boffset << PAGE_SHIFT); 1107 } 1108 } 1109 1110 /* 1111 * Get a block given a specified block and offset into a file/device. 1112 */ 1113 struct buf * 1114 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo) 1115 { 1116 struct buf *bp; 1117 int s; 1118 struct bufhashhdr *bh; 1119 int maxsize; 1120 1121 if (vp->v_mount) { 1122 maxsize = vp->v_mount->mnt_stat.f_iosize; 1123 /* 1124 * This happens on mount points. 1125 */ 1126 if (maxsize < size) 1127 maxsize = size; 1128 } else { 1129 maxsize = size; 1130 } 1131 1132 if (size > MAXBSIZE) 1133 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 1134 1135 s = splbio(); 1136 loop: 1137 if ((bp = gbincore(vp, blkno))) { 1138 if (bp->b_flags & B_BUSY) { 1139 bp->b_flags |= B_WANTED; 1140 if (bp->b_usecount < BUF_MAXUSE) 1141 ++bp->b_usecount; 1142 if (!tsleep(bp, 1143 (PRIBIO + 1) | slpflag, "getblk", slptimeo)) 1144 goto loop; 1145 1146 splx(s); 1147 return (struct buf *) NULL; 1148 } 1149 bp->b_flags |= B_BUSY | B_CACHE; 1150 bremfree(bp); 1151 1152 /* 1153 * check for size inconsistancies (note that they shouldn't happen 1154 * but do when filesystems don't handle the size changes correctly.) 1155 * We are conservative on metadata and don't just extend the buffer 1156 * but write and re-constitute it. 1157 */ 1158 1159 if (bp->b_bcount != size) { 1160 if ((bp->b_flags & B_VMIO) && (size <= bp->b_kvasize)) { 1161 allocbuf(bp, size); 1162 } else { 1163 bp->b_flags |= B_NOCACHE; 1164 VOP_BWRITE(bp); 1165 goto loop; 1166 } 1167 } 1168 1169 if (bp->b_usecount < BUF_MAXUSE) 1170 ++bp->b_usecount; 1171 splx(s); 1172 return (bp); 1173 } else { 1174 vm_object_t obj; 1175 1176 if ((bp = getnewbuf(slpflag, slptimeo, size, maxsize)) == 0) { 1177 if (slpflag || slptimeo) { 1178 splx(s); 1179 return NULL; 1180 } 1181 goto loop; 1182 } 1183 1184 /* 1185 * This code is used to make sure that a buffer is not 1186 * created while the getnewbuf routine is blocked. 1187 * This can be a problem whether the vnode is locked or not. 1188 */ 1189 if (gbincore(vp, blkno)) { 1190 bp->b_flags |= B_INVAL; 1191 brelse(bp); 1192 goto loop; 1193 } 1194 1195 /* 1196 * Insert the buffer into the hash, so that it can 1197 * be found by incore. 1198 */ 1199 bp->b_blkno = bp->b_lblkno = blkno; 1200 bgetvp(vp, bp); 1201 LIST_REMOVE(bp, b_hash); 1202 bh = BUFHASH(vp, blkno); 1203 LIST_INSERT_HEAD(bh, bp, b_hash); 1204 1205 if ((obj = vp->v_object) && (vp->v_flag & VVMIO)) { 1206 bp->b_flags |= (B_VMIO | B_CACHE); 1207 #if defined(VFS_BIO_DEBUG) 1208 if (vp->v_type != VREG && vp->v_type != VBLK) 1209 printf("getblk: vmioing file type %d???\n", vp->v_type); 1210 #endif 1211 } else { 1212 bp->b_flags &= ~B_VMIO; 1213 } 1214 splx(s); 1215 1216 allocbuf(bp, size); 1217 #ifdef PC98 1218 /* 1219 * 1024byte/sector support 1220 */ 1221 #define B_XXX2 0x8000000 1222 if (vp->v_flag & 0x10000) bp->b_flags |= B_XXX2; 1223 #endif 1224 return (bp); 1225 } 1226 } 1227 1228 /* 1229 * Get an empty, disassociated buffer of given size. 1230 */ 1231 struct buf * 1232 geteblk(int size) 1233 { 1234 struct buf *bp; 1235 int s; 1236 1237 s = splbio(); 1238 while ((bp = getnewbuf(0, 0, size, MAXBSIZE)) == 0); 1239 splx(s); 1240 allocbuf(bp, size); 1241 bp->b_flags |= B_INVAL; 1242 return (bp); 1243 } 1244 1245 1246 /* 1247 * This code constitutes the buffer memory from either anonymous system 1248 * memory (in the case of non-VMIO operations) or from an associated 1249 * VM object (in the case of VMIO operations). 1250 * 1251 * Note that this code is tricky, and has many complications to resolve 1252 * deadlock or inconsistant data situations. Tread lightly!!! 1253 * 1254 * Modify the length of a buffer's underlying buffer storage without 1255 * destroying information (unless, of course the buffer is shrinking). 1256 */ 1257 int 1258 allocbuf(struct buf * bp, int size) 1259 { 1260 1261 int s; 1262 int newbsize, mbsize; 1263 int i; 1264 1265 if (!(bp->b_flags & B_BUSY)) 1266 panic("allocbuf: buffer not busy"); 1267 1268 if (bp->b_kvasize < size) 1269 panic("allocbuf: buffer too small"); 1270 1271 if ((bp->b_flags & B_VMIO) == 0) { 1272 caddr_t origbuf; 1273 int origbufsize; 1274 /* 1275 * Just get anonymous memory from the kernel 1276 */ 1277 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 1278 #if !defined(NO_B_MALLOC) 1279 if (bp->b_flags & B_MALLOC) 1280 newbsize = mbsize; 1281 else 1282 #endif 1283 newbsize = round_page(size); 1284 1285 if (newbsize < bp->b_bufsize) { 1286 #if !defined(NO_B_MALLOC) 1287 /* 1288 * malloced buffers are not shrunk 1289 */ 1290 if (bp->b_flags & B_MALLOC) { 1291 if (newbsize) { 1292 bp->b_bcount = size; 1293 } else { 1294 free(bp->b_data, M_BIOBUF); 1295 bufspace -= bp->b_bufsize; 1296 bufmallocspace -= bp->b_bufsize; 1297 bp->b_data = bp->b_kvabase; 1298 bp->b_bufsize = 0; 1299 bp->b_bcount = 0; 1300 bp->b_flags &= ~B_MALLOC; 1301 } 1302 return 1; 1303 } 1304 #endif 1305 vm_hold_free_pages( 1306 bp, 1307 (vm_offset_t) bp->b_data + newbsize, 1308 (vm_offset_t) bp->b_data + bp->b_bufsize); 1309 } else if (newbsize > bp->b_bufsize) { 1310 #if !defined(NO_B_MALLOC) 1311 /* 1312 * We only use malloced memory on the first allocation. 1313 * and revert to page-allocated memory when the buffer grows. 1314 */ 1315 if ( (bufmallocspace < maxbufmallocspace) && 1316 (bp->b_bufsize == 0) && 1317 (mbsize <= PAGE_SIZE/2)) { 1318 1319 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 1320 bp->b_bufsize = mbsize; 1321 bp->b_bcount = size; 1322 bp->b_flags |= B_MALLOC; 1323 bufspace += mbsize; 1324 bufmallocspace += mbsize; 1325 return 1; 1326 } 1327 #endif 1328 origbuf = NULL; 1329 origbufsize = 0; 1330 #if !defined(NO_B_MALLOC) 1331 /* 1332 * If the buffer is growing on it's other-than-first allocation, 1333 * then we revert to the page-allocation scheme. 1334 */ 1335 if (bp->b_flags & B_MALLOC) { 1336 origbuf = bp->b_data; 1337 origbufsize = bp->b_bufsize; 1338 bp->b_data = bp->b_kvabase; 1339 bufspace -= bp->b_bufsize; 1340 bufmallocspace -= bp->b_bufsize; 1341 bp->b_bufsize = 0; 1342 bp->b_flags &= ~B_MALLOC; 1343 newbsize = round_page(newbsize); 1344 } 1345 #endif 1346 vm_hold_load_pages( 1347 bp, 1348 (vm_offset_t) bp->b_data + bp->b_bufsize, 1349 (vm_offset_t) bp->b_data + newbsize); 1350 #if !defined(NO_B_MALLOC) 1351 if (origbuf) { 1352 bcopy(origbuf, bp->b_data, origbufsize); 1353 free(origbuf, M_BIOBUF); 1354 } 1355 #endif 1356 } 1357 } else { 1358 vm_page_t m; 1359 int desiredpages; 1360 1361 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 1362 desiredpages = (round_page(newbsize) >> PAGE_SHIFT); 1363 1364 #if !defined(NO_B_MALLOC) 1365 if (bp->b_flags & B_MALLOC) 1366 panic("allocbuf: VMIO buffer can't be malloced"); 1367 #endif 1368 1369 if (newbsize < bp->b_bufsize) { 1370 if (desiredpages < bp->b_npages) { 1371 for (i = desiredpages; i < bp->b_npages; i++) { 1372 /* 1373 * the page is not freed here -- it 1374 * is the responsibility of vnode_pager_setsize 1375 */ 1376 m = bp->b_pages[i]; 1377 #if defined(DIAGNOSTIC) 1378 if (m == bogus_page) 1379 panic("allocbuf: bogus page found"); 1380 #endif 1381 s = splvm(); 1382 while ((m->flags & PG_BUSY) || (m->busy != 0)) { 1383 m->flags |= PG_WANTED; 1384 tsleep(m, PVM, "biodep", 0); 1385 } 1386 splx(s); 1387 1388 bp->b_pages[i] = NULL; 1389 vm_page_unwire(m); 1390 } 1391 pmap_qremove((vm_offset_t) trunc_page(bp->b_data) + 1392 (desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages)); 1393 bp->b_npages = desiredpages; 1394 } 1395 } else if (newbsize > bp->b_bufsize) { 1396 vm_object_t obj; 1397 vm_offset_t tinc, toff; 1398 vm_ooffset_t off; 1399 vm_pindex_t objoff; 1400 int pageindex, curbpnpages; 1401 struct vnode *vp; 1402 int bsize; 1403 1404 vp = bp->b_vp; 1405 1406 if (vp->v_type == VBLK) 1407 bsize = DEV_BSIZE; 1408 else 1409 bsize = vp->v_mount->mnt_stat.f_iosize; 1410 1411 if (bp->b_npages < desiredpages) { 1412 obj = vp->v_object; 1413 tinc = PAGE_SIZE; 1414 if (tinc > bsize) 1415 tinc = bsize; 1416 off = (vm_ooffset_t) bp->b_lblkno * bsize; 1417 curbpnpages = bp->b_npages; 1418 doretry: 1419 bp->b_flags |= B_CACHE; 1420 bp->b_validoff = bp->b_validend = 0; 1421 for (toff = 0; toff < newbsize; toff += tinc) { 1422 int bytesinpage; 1423 1424 pageindex = toff >> PAGE_SHIFT; 1425 objoff = OFF_TO_IDX(off + toff); 1426 if (pageindex < curbpnpages) { 1427 1428 m = bp->b_pages[pageindex]; 1429 #ifdef VFS_BIO_DIAG 1430 if (m->pindex != objoff) 1431 panic("allocbuf: page changed offset??!!!?"); 1432 #endif 1433 bytesinpage = tinc; 1434 if (tinc > (newbsize - toff)) 1435 bytesinpage = newbsize - toff; 1436 if (bp->b_flags & B_CACHE) 1437 vfs_buf_set_valid(bp, off, toff, bytesinpage, m); 1438 continue; 1439 } 1440 m = vm_page_lookup(obj, objoff); 1441 if (!m) { 1442 m = vm_page_alloc(obj, objoff, VM_ALLOC_NORMAL); 1443 if (!m) { 1444 VM_WAIT; 1445 goto doretry; 1446 } 1447 /* 1448 * Normally it is unwise to clear PG_BUSY without 1449 * PAGE_WAKEUP -- but it is okay here, as there is 1450 * no chance for blocking between here and vm_page_alloc 1451 */ 1452 m->flags &= ~PG_BUSY; 1453 vm_page_wire(m); 1454 bp->b_flags &= ~B_CACHE; 1455 } else if (m->flags & PG_BUSY) { 1456 s = splvm(); 1457 if (m->flags & PG_BUSY) { 1458 m->flags |= PG_WANTED; 1459 tsleep(m, PVM, "pgtblk", 0); 1460 } 1461 splx(s); 1462 goto doretry; 1463 } else { 1464 if ((curproc != pageproc) && 1465 ((m->queue - m->pc) == PQ_CACHE) && 1466 ((cnt.v_free_count + cnt.v_cache_count) < 1467 (cnt.v_free_min + cnt.v_cache_min))) { 1468 pagedaemon_wakeup(); 1469 } 1470 bytesinpage = tinc; 1471 if (tinc > (newbsize - toff)) 1472 bytesinpage = newbsize - toff; 1473 if (bp->b_flags & B_CACHE) 1474 vfs_buf_set_valid(bp, off, toff, bytesinpage, m); 1475 vm_page_wire(m); 1476 } 1477 bp->b_pages[pageindex] = m; 1478 curbpnpages = pageindex + 1; 1479 } 1480 if (vp->v_tag == VT_NFS && 1481 vp->v_type != VBLK && 1482 bp->b_validend == 0) 1483 bp->b_flags &= ~B_CACHE; 1484 bp->b_data = (caddr_t) trunc_page(bp->b_data); 1485 bp->b_npages = curbpnpages; 1486 pmap_qenter((vm_offset_t) bp->b_data, 1487 bp->b_pages, bp->b_npages); 1488 ((vm_offset_t) bp->b_data) |= off & PAGE_MASK; 1489 } 1490 } 1491 } 1492 if (bp->b_flags & B_VMIO) 1493 vmiospace += bp->b_bufsize; 1494 bufspace += (newbsize - bp->b_bufsize); 1495 bp->b_bufsize = newbsize; 1496 bp->b_bcount = size; 1497 return 1; 1498 } 1499 1500 /* 1501 * Wait for buffer I/O completion, returning error status. 1502 */ 1503 int 1504 biowait(register struct buf * bp) 1505 { 1506 int s; 1507 1508 s = splbio(); 1509 while ((bp->b_flags & B_DONE) == 0) 1510 tsleep(bp, PRIBIO, "biowait", 0); 1511 splx(s); 1512 if (bp->b_flags & B_EINTR) { 1513 bp->b_flags &= ~B_EINTR; 1514 return (EINTR); 1515 } 1516 if (bp->b_flags & B_ERROR) { 1517 return (bp->b_error ? bp->b_error : EIO); 1518 } else { 1519 return (0); 1520 } 1521 } 1522 1523 /* 1524 * Finish I/O on a buffer, calling an optional function. 1525 * This is usually called from interrupt level, so process blocking 1526 * is not *a good idea*. 1527 */ 1528 void 1529 biodone(register struct buf * bp) 1530 { 1531 int s; 1532 1533 s = splbio(); 1534 if (!(bp->b_flags & B_BUSY)) 1535 panic("biodone: buffer not busy"); 1536 1537 if (bp->b_flags & B_DONE) { 1538 splx(s); 1539 printf("biodone: buffer already done\n"); 1540 return; 1541 } 1542 bp->b_flags |= B_DONE; 1543 1544 if ((bp->b_flags & B_READ) == 0) { 1545 vwakeup(bp); 1546 } 1547 #ifdef BOUNCE_BUFFERS 1548 if (bp->b_flags & B_BOUNCE) 1549 vm_bounce_free(bp); 1550 #endif 1551 1552 /* call optional completion function if requested */ 1553 if (bp->b_flags & B_CALL) { 1554 bp->b_flags &= ~B_CALL; 1555 (*bp->b_iodone) (bp); 1556 splx(s); 1557 return; 1558 } 1559 if (bp->b_flags & B_VMIO) { 1560 int i, resid; 1561 vm_ooffset_t foff; 1562 vm_page_t m; 1563 vm_object_t obj; 1564 int iosize; 1565 struct vnode *vp = bp->b_vp; 1566 1567 if (vp->v_type == VBLK) 1568 foff = (vm_ooffset_t) DEV_BSIZE * bp->b_lblkno; 1569 else 1570 foff = (vm_ooffset_t) vp->v_mount->mnt_stat.f_iosize * bp->b_lblkno; 1571 obj = vp->v_object; 1572 if (!obj) { 1573 panic("biodone: no object"); 1574 } 1575 #if defined(VFS_BIO_DEBUG) 1576 if (obj->paging_in_progress < bp->b_npages) { 1577 printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n", 1578 obj->paging_in_progress, bp->b_npages); 1579 } 1580 #endif 1581 iosize = bp->b_bufsize; 1582 for (i = 0; i < bp->b_npages; i++) { 1583 int bogusflag = 0; 1584 m = bp->b_pages[i]; 1585 if (m == bogus_page) { 1586 bogusflag = 1; 1587 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 1588 if (!m) { 1589 #if defined(VFS_BIO_DEBUG) 1590 printf("biodone: page disappeared\n"); 1591 #endif 1592 --obj->paging_in_progress; 1593 continue; 1594 } 1595 bp->b_pages[i] = m; 1596 pmap_qenter(trunc_page(bp->b_data), bp->b_pages, bp->b_npages); 1597 } 1598 #if defined(VFS_BIO_DEBUG) 1599 if (OFF_TO_IDX(foff) != m->pindex) { 1600 printf("biodone: foff(%d)/m->pindex(%d) mismatch\n", foff, m->pindex); 1601 } 1602 #endif 1603 resid = IDX_TO_OFF(m->pindex + 1) - foff; 1604 if (resid > iosize) 1605 resid = iosize; 1606 /* 1607 * In the write case, the valid and clean bits are 1608 * already changed correctly, so we only need to do this 1609 * here in the read case. 1610 */ 1611 if ((bp->b_flags & B_READ) && !bogusflag && resid > 0) { 1612 vfs_page_set_valid(bp, foff, i, m); 1613 } 1614 1615 /* 1616 * when debugging new filesystems or buffer I/O methods, this 1617 * is the most common error that pops up. if you see this, you 1618 * have not set the page busy flag correctly!!! 1619 */ 1620 if (m->busy == 0) { 1621 printf("biodone: page busy < 0, " 1622 "pindex: %d, foff: 0x(%x,%x), " 1623 "resid: %d, index: %d\n", 1624 (int) m->pindex, (int)(foff >> 32), 1625 (int) foff & 0xffffffff, resid, i); 1626 if (vp->v_type != VBLK) 1627 printf(" iosize: %ld, lblkno: %d, flags: 0x%lx, npages: %d\n", 1628 bp->b_vp->v_mount->mnt_stat.f_iosize, 1629 (int) bp->b_lblkno, 1630 bp->b_flags, bp->b_npages); 1631 else 1632 printf(" VDEV, lblkno: %d, flags: 0x%lx, npages: %d\n", 1633 (int) bp->b_lblkno, 1634 bp->b_flags, bp->b_npages); 1635 printf(" valid: 0x%x, dirty: 0x%x, wired: %d\n", 1636 m->valid, m->dirty, m->wire_count); 1637 panic("biodone: page busy < 0\n"); 1638 } 1639 --m->busy; 1640 if ((m->busy == 0) && (m->flags & PG_WANTED)) { 1641 m->flags &= ~PG_WANTED; 1642 wakeup(m); 1643 } 1644 --obj->paging_in_progress; 1645 foff += resid; 1646 iosize -= resid; 1647 } 1648 if (obj && obj->paging_in_progress == 0 && 1649 (obj->flags & OBJ_PIPWNT)) { 1650 obj->flags &= ~OBJ_PIPWNT; 1651 wakeup(obj); 1652 } 1653 } 1654 /* 1655 * For asynchronous completions, release the buffer now. The brelse 1656 * checks for B_WANTED and will do the wakeup there if necessary - so 1657 * no need to do a wakeup here in the async case. 1658 */ 1659 1660 if (bp->b_flags & B_ASYNC) { 1661 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR | B_RELBUF)) != 0) 1662 brelse(bp); 1663 else 1664 bqrelse(bp); 1665 } else { 1666 bp->b_flags &= ~B_WANTED; 1667 wakeup(bp); 1668 } 1669 splx(s); 1670 } 1671 1672 int 1673 count_lock_queue() 1674 { 1675 int count; 1676 struct buf *bp; 1677 1678 count = 0; 1679 for (bp = TAILQ_FIRST(&bufqueues[QUEUE_LOCKED]); 1680 bp != NULL; 1681 bp = TAILQ_NEXT(bp, b_freelist)) 1682 count++; 1683 return (count); 1684 } 1685 1686 int vfs_update_interval = 30; 1687 1688 static void 1689 vfs_update() 1690 { 1691 while (1) { 1692 tsleep(&vfs_update_wakeup, PUSER, "update", 1693 hz * vfs_update_interval); 1694 vfs_update_wakeup = 0; 1695 sync(curproc, NULL, NULL); 1696 } 1697 } 1698 1699 static int 1700 sysctl_kern_updateinterval SYSCTL_HANDLER_ARGS 1701 { 1702 int error = sysctl_handle_int(oidp, 1703 oidp->oid_arg1, oidp->oid_arg2, req); 1704 if (!error) 1705 wakeup(&vfs_update_wakeup); 1706 return error; 1707 } 1708 1709 SYSCTL_PROC(_kern, KERN_UPDATEINTERVAL, update, CTLTYPE_INT|CTLFLAG_RW, 1710 &vfs_update_interval, 0, sysctl_kern_updateinterval, "I", ""); 1711 1712 1713 /* 1714 * This routine is called in lieu of iodone in the case of 1715 * incomplete I/O. This keeps the busy status for pages 1716 * consistant. 1717 */ 1718 void 1719 vfs_unbusy_pages(struct buf * bp) 1720 { 1721 int i; 1722 1723 if (bp->b_flags & B_VMIO) { 1724 struct vnode *vp = bp->b_vp; 1725 vm_object_t obj = vp->v_object; 1726 vm_ooffset_t foff; 1727 1728 foff = (vm_ooffset_t) vp->v_mount->mnt_stat.f_iosize * bp->b_lblkno; 1729 1730 for (i = 0; i < bp->b_npages; i++) { 1731 vm_page_t m = bp->b_pages[i]; 1732 1733 if (m == bogus_page) { 1734 m = vm_page_lookup(obj, OFF_TO_IDX(foff) + i); 1735 if (!m) { 1736 panic("vfs_unbusy_pages: page missing\n"); 1737 } 1738 bp->b_pages[i] = m; 1739 pmap_qenter(trunc_page(bp->b_data), bp->b_pages, bp->b_npages); 1740 } 1741 --obj->paging_in_progress; 1742 --m->busy; 1743 if ((m->busy == 0) && (m->flags & PG_WANTED)) { 1744 m->flags &= ~PG_WANTED; 1745 wakeup(m); 1746 } 1747 } 1748 if (obj->paging_in_progress == 0 && 1749 (obj->flags & OBJ_PIPWNT)) { 1750 obj->flags &= ~OBJ_PIPWNT; 1751 wakeup(obj); 1752 } 1753 } 1754 } 1755 1756 /* 1757 * Set NFS' b_validoff and b_validend fields from the valid bits 1758 * of a page. If the consumer is not NFS, and the page is not 1759 * valid for the entire range, clear the B_CACHE flag to force 1760 * the consumer to re-read the page. 1761 */ 1762 static void 1763 vfs_buf_set_valid(struct buf *bp, 1764 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 1765 vm_page_t m) 1766 { 1767 if (bp->b_vp->v_tag == VT_NFS && bp->b_vp->v_type != VBLK) { 1768 vm_offset_t svalid, evalid; 1769 int validbits = m->valid; 1770 1771 /* 1772 * This only bothers with the first valid range in the 1773 * page. 1774 */ 1775 svalid = off; 1776 while (validbits && !(validbits & 1)) { 1777 svalid += DEV_BSIZE; 1778 validbits >>= 1; 1779 } 1780 evalid = svalid; 1781 while (validbits & 1) { 1782 evalid += DEV_BSIZE; 1783 validbits >>= 1; 1784 } 1785 /* 1786 * Make sure this range is contiguous with the range 1787 * built up from previous pages. If not, then we will 1788 * just use the range from the previous pages. 1789 */ 1790 if (svalid == bp->b_validend) { 1791 bp->b_validoff = min(bp->b_validoff, svalid); 1792 bp->b_validend = max(bp->b_validend, evalid); 1793 } 1794 } else if (!vm_page_is_valid(m, 1795 (vm_offset_t) ((foff + off) & PAGE_MASK), 1796 size)) { 1797 bp->b_flags &= ~B_CACHE; 1798 } 1799 } 1800 1801 /* 1802 * Set the valid bits in a page, taking care of the b_validoff, 1803 * b_validend fields which NFS uses to optimise small reads. Off is 1804 * the offset within the file and pageno is the page index within the buf. 1805 */ 1806 static void 1807 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m) 1808 { 1809 struct vnode *vp = bp->b_vp; 1810 vm_ooffset_t soff, eoff; 1811 1812 soff = off; 1813 eoff = off + min(PAGE_SIZE, bp->b_bufsize); 1814 vm_page_set_invalid(m, 1815 (vm_offset_t) (soff & PAGE_MASK), 1816 (vm_offset_t) (eoff - soff)); 1817 if (vp->v_tag == VT_NFS && vp->v_type != VBLK) { 1818 vm_ooffset_t sv, ev; 1819 off = off - pageno * PAGE_SIZE; 1820 sv = off + ((bp->b_validoff + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1)); 1821 ev = off + ((bp->b_validend + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1)); 1822 soff = max(sv, soff); 1823 eoff = min(ev, eoff); 1824 } 1825 if (eoff > soff) 1826 vm_page_set_validclean(m, 1827 (vm_offset_t) (soff & PAGE_MASK), 1828 (vm_offset_t) (eoff - soff)); 1829 } 1830 1831 /* 1832 * This routine is called before a device strategy routine. 1833 * It is used to tell the VM system that paging I/O is in 1834 * progress, and treat the pages associated with the buffer 1835 * almost as being PG_BUSY. Also the object paging_in_progress 1836 * flag is handled to make sure that the object doesn't become 1837 * inconsistant. 1838 */ 1839 void 1840 vfs_busy_pages(struct buf * bp, int clear_modify) 1841 { 1842 int i; 1843 1844 if (bp->b_flags & B_VMIO) { 1845 struct vnode *vp = bp->b_vp; 1846 vm_object_t obj = vp->v_object; 1847 vm_ooffset_t foff; 1848 1849 if (vp->v_type == VBLK) 1850 foff = (vm_ooffset_t) DEV_BSIZE * bp->b_lblkno; 1851 else 1852 foff = (vm_ooffset_t) vp->v_mount->mnt_stat.f_iosize * bp->b_lblkno; 1853 vfs_setdirty(bp); 1854 for (i = 0; i < bp->b_npages; i++, foff += PAGE_SIZE) { 1855 vm_page_t m = bp->b_pages[i]; 1856 1857 if ((bp->b_flags & B_CLUSTER) == 0) { 1858 obj->paging_in_progress++; 1859 m->busy++; 1860 } 1861 vm_page_protect(m, VM_PROT_NONE); 1862 if (clear_modify) 1863 vfs_page_set_valid(bp, foff, i, m); 1864 else if (bp->b_bcount >= PAGE_SIZE) { 1865 if (m->valid && (bp->b_flags & B_CACHE) == 0) { 1866 bp->b_pages[i] = bogus_page; 1867 pmap_qenter(trunc_page(bp->b_data), bp->b_pages, bp->b_npages); 1868 } 1869 } 1870 } 1871 } 1872 } 1873 1874 /* 1875 * Tell the VM system that the pages associated with this buffer 1876 * are clean. This is used for delayed writes where the data is 1877 * going to go to disk eventually without additional VM intevention. 1878 */ 1879 void 1880 vfs_clean_pages(struct buf * bp) 1881 { 1882 int i; 1883 1884 if (bp->b_flags & B_VMIO) { 1885 struct vnode *vp = bp->b_vp; 1886 vm_object_t obj = vp->v_object; 1887 vm_ooffset_t foff; 1888 1889 if (vp->v_type == VBLK) 1890 foff = (vm_ooffset_t) DEV_BSIZE * bp->b_lblkno; 1891 else 1892 foff = (vm_ooffset_t) vp->v_mount->mnt_stat.f_iosize * bp->b_lblkno; 1893 for (i = 0; i < bp->b_npages; i++, foff += PAGE_SIZE) { 1894 vm_page_t m = bp->b_pages[i]; 1895 1896 vfs_page_set_valid(bp, foff, i, m); 1897 } 1898 } 1899 } 1900 1901 void 1902 vfs_bio_clrbuf(struct buf *bp) { 1903 int i; 1904 if( bp->b_flags & B_VMIO) { 1905 if( (bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE)) { 1906 int mask; 1907 mask = 0; 1908 for(i=0;i<bp->b_bufsize;i+=DEV_BSIZE) 1909 mask |= (1 << (i/DEV_BSIZE)); 1910 if( bp->b_pages[0]->valid != mask) { 1911 bzero(bp->b_data, bp->b_bufsize); 1912 } 1913 bp->b_pages[0]->valid = mask; 1914 bp->b_resid = 0; 1915 return; 1916 } 1917 for(i=0;i<bp->b_npages;i++) { 1918 if( bp->b_pages[i]->valid == VM_PAGE_BITS_ALL) 1919 continue; 1920 if( bp->b_pages[i]->valid == 0) { 1921 if ((bp->b_pages[i]->flags & PG_ZERO) == 0) { 1922 bzero(bp->b_data + (i << PAGE_SHIFT), PAGE_SIZE); 1923 } 1924 } else { 1925 int j; 1926 for(j=0;j<PAGE_SIZE/DEV_BSIZE;j++) { 1927 if( (bp->b_pages[i]->valid & (1<<j)) == 0) 1928 bzero(bp->b_data + (i << PAGE_SHIFT) + j * DEV_BSIZE, DEV_BSIZE); 1929 } 1930 } 1931 /* bp->b_pages[i]->valid = VM_PAGE_BITS_ALL; */ 1932 } 1933 bp->b_resid = 0; 1934 } else { 1935 clrbuf(bp); 1936 } 1937 } 1938 1939 /* 1940 * vm_hold_load_pages and vm_hold_unload pages get pages into 1941 * a buffers address space. The pages are anonymous and are 1942 * not associated with a file object. 1943 */ 1944 void 1945 vm_hold_load_pages(struct buf * bp, vm_offset_t from, vm_offset_t to) 1946 { 1947 vm_offset_t pg; 1948 vm_page_t p; 1949 int index; 1950 1951 to = round_page(to); 1952 from = round_page(from); 1953 index = (from - trunc_page(bp->b_data)) >> PAGE_SHIFT; 1954 1955 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 1956 1957 tryagain: 1958 1959 p = vm_page_alloc(kernel_object, ((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 1960 VM_ALLOC_NORMAL); 1961 if (!p) { 1962 VM_WAIT; 1963 goto tryagain; 1964 } 1965 vm_page_wire(p); 1966 pmap_kenter(pg, VM_PAGE_TO_PHYS(p)); 1967 bp->b_pages[index] = p; 1968 PAGE_WAKEUP(p); 1969 } 1970 bp->b_npages = to >> PAGE_SHIFT; 1971 } 1972 1973 void 1974 vm_hold_free_pages(struct buf * bp, vm_offset_t from, vm_offset_t to) 1975 { 1976 vm_offset_t pg; 1977 vm_page_t p; 1978 int index; 1979 1980 from = round_page(from); 1981 to = round_page(to); 1982 index = (from - trunc_page(bp->b_data)) >> PAGE_SHIFT; 1983 1984 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 1985 p = bp->b_pages[index]; 1986 if (p && (index < bp->b_npages)) { 1987 if (p->busy) { 1988 printf("vm_hold_free_pages: blkno: %d, lblkno: %d\n", 1989 bp->b_blkno, bp->b_lblkno); 1990 } 1991 bp->b_pages[index] = NULL; 1992 pmap_kremove(pg); 1993 vm_page_unwire(p); 1994 vm_page_free(p); 1995 } 1996 } 1997 bp->b_npages = from >> PAGE_SHIFT; 1998 }
Cache object: 3e54aeefe771eedf0898a598992b59c3
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