1 /* 2 * Copyright (c) 1994,1997 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. Absolutely no warranty of function or purpose is made by the author 12 * John S. Dyson. 13 * 14 * $FreeBSD: src/sys/kern/vfs_bio.c,v 1.242.2.20 2003/05/28 18:38:10 alc Exp $ 15 */ 16 17 /* 18 * this file contains a new buffer I/O scheme implementing a coherent 19 * VM object and buffer cache scheme. Pains have been taken to make 20 * sure that the performance degradation associated with schemes such 21 * as this is not realized. 22 * 23 * Author: John S. Dyson 24 * Significant help during the development and debugging phases 25 * had been provided by David Greenman, also of the FreeBSD core team. 26 * 27 * see man buf(9) for more info. 28 */ 29 30 #include <sys/param.h> 31 #include <sys/systm.h> 32 #include <sys/buf.h> 33 #include <sys/conf.h> 34 #include <sys/eventhandler.h> 35 #include <sys/lock.h> 36 #include <sys/malloc.h> 37 #include <sys/mount.h> 38 #include <sys/kernel.h> 39 #include <sys/kthread.h> 40 #include <sys/proc.h> 41 #include <sys/reboot.h> 42 #include <sys/resourcevar.h> 43 #include <sys/sysctl.h> 44 #include <sys/vmmeter.h> 45 #include <sys/vnode.h> 46 #include <vm/vm.h> 47 #include <vm/vm_param.h> 48 #include <vm/vm_kern.h> 49 #include <vm/vm_pageout.h> 50 #include <vm/vm_page.h> 51 #include <vm/vm_object.h> 52 #include <vm/vm_extern.h> 53 #include <vm/vm_map.h> 54 55 static MALLOC_DEFINE(M_BIOBUF, "BIO buffer", "BIO buffer"); 56 57 struct bio_ops bioops; /* I/O operation notification */ 58 59 struct buf *buf; /* buffer header pool */ 60 struct swqueue bswlist; 61 62 static void vm_hold_free_pages(struct buf * bp, vm_offset_t from, 63 vm_offset_t to); 64 static void vm_hold_load_pages(struct buf * bp, vm_offset_t from, 65 vm_offset_t to); 66 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, 67 int pageno, vm_page_t m); 68 static void vfs_clean_pages(struct buf * bp); 69 static void vfs_setdirty(struct buf *bp); 70 static void vfs_vmio_release(struct buf *bp); 71 static void vfs_backgroundwritedone(struct buf *bp); 72 static int flushbufqueues(void); 73 74 static int bd_request; 75 76 static void buf_daemon __P((void)); 77 /* 78 * bogus page -- for I/O to/from partially complete buffers 79 * this is a temporary solution to the problem, but it is not 80 * really that bad. it would be better to split the buffer 81 * for input in the case of buffers partially already in memory, 82 * but the code is intricate enough already. 83 */ 84 vm_page_t bogus_page; 85 int vmiodirenable = TRUE; 86 int runningbufspace; 87 static vm_offset_t bogus_offset; 88 89 static int bufspace, maxbufspace, 90 bufmallocspace, maxbufmallocspace, lobufspace, hibufspace; 91 static int bufreusecnt, bufdefragcnt, buffreekvacnt; 92 static int needsbuffer; 93 static int lorunningspace, hirunningspace, runningbufreq; 94 static int numdirtybuffers, lodirtybuffers, hidirtybuffers; 95 static int numfreebuffers, lofreebuffers, hifreebuffers; 96 static int getnewbufcalls; 97 static int getnewbufrestarts; 98 99 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, 100 &numdirtybuffers, 0, ""); 101 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, 102 &lodirtybuffers, 0, ""); 103 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, 104 &hidirtybuffers, 0, ""); 105 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, 106 &numfreebuffers, 0, ""); 107 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, 108 &lofreebuffers, 0, ""); 109 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, 110 &hifreebuffers, 0, ""); 111 SYSCTL_INT(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, 112 &runningbufspace, 0, ""); 113 SYSCTL_INT(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, 114 &lorunningspace, 0, ""); 115 SYSCTL_INT(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, 116 &hirunningspace, 0, ""); 117 SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, 118 &maxbufspace, 0, ""); 119 SYSCTL_INT(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, 120 &hibufspace, 0, ""); 121 SYSCTL_INT(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, 122 &lobufspace, 0, ""); 123 SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, 124 &bufspace, 0, ""); 125 SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, 126 &maxbufmallocspace, 0, ""); 127 SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, 128 &bufmallocspace, 0, ""); 129 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, 130 &getnewbufcalls, 0, ""); 131 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, 132 &getnewbufrestarts, 0, ""); 133 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, 134 &vmiodirenable, 0, ""); 135 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, 136 &bufdefragcnt, 0, ""); 137 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, 138 &buffreekvacnt, 0, ""); 139 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, 140 &bufreusecnt, 0, ""); 141 142 static int bufhashmask; 143 static LIST_HEAD(bufhashhdr, buf) *bufhashtbl, invalhash; 144 struct bqueues bufqueues[BUFFER_QUEUES] = { { 0 } }; 145 char *buf_wmesg = BUF_WMESG; 146 147 extern int vm_swap_size; 148 149 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 150 #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */ 151 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ 152 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 153 154 /* 155 * Buffer hash table code. Note that the logical block scans linearly, which 156 * gives us some L1 cache locality. 157 */ 158 159 static __inline 160 struct bufhashhdr * 161 bufhash(struct vnode *vnp, daddr_t bn) 162 { 163 return(&bufhashtbl[(((uintptr_t)(vnp) >> 7) + (int)bn) & bufhashmask]); 164 } 165 166 /* 167 * numdirtywakeup: 168 * 169 * If someone is blocked due to there being too many dirty buffers, 170 * and numdirtybuffers is now reasonable, wake them up. 171 */ 172 173 static __inline void 174 numdirtywakeup(int level) 175 { 176 if (numdirtybuffers <= level) { 177 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) { 178 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH; 179 wakeup(&needsbuffer); 180 } 181 } 182 } 183 184 /* 185 * bufspacewakeup: 186 * 187 * Called when buffer space is potentially available for recovery. 188 * getnewbuf() will block on this flag when it is unable to free 189 * sufficient buffer space. Buffer space becomes recoverable when 190 * bp's get placed back in the queues. 191 */ 192 193 static __inline void 194 bufspacewakeup(void) 195 { 196 /* 197 * If someone is waiting for BUF space, wake them up. Even 198 * though we haven't freed the kva space yet, the waiting 199 * process will be able to now. 200 */ 201 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) { 202 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE; 203 wakeup(&needsbuffer); 204 } 205 } 206 207 /* 208 * runningbufwakeup() - in-progress I/O accounting. 209 * 210 */ 211 static __inline void 212 runningbufwakeup(struct buf *bp) 213 { 214 if (bp->b_runningbufspace) { 215 runningbufspace -= bp->b_runningbufspace; 216 bp->b_runningbufspace = 0; 217 if (runningbufreq && runningbufspace <= lorunningspace) { 218 runningbufreq = 0; 219 wakeup(&runningbufreq); 220 } 221 } 222 } 223 224 /* 225 * bufcountwakeup: 226 * 227 * Called when a buffer has been added to one of the free queues to 228 * account for the buffer and to wakeup anyone waiting for free buffers. 229 * This typically occurs when large amounts of metadata are being handled 230 * by the buffer cache ( else buffer space runs out first, usually ). 231 */ 232 233 static __inline void 234 bufcountwakeup(void) 235 { 236 ++numfreebuffers; 237 if (needsbuffer) { 238 needsbuffer &= ~VFS_BIO_NEED_ANY; 239 if (numfreebuffers >= hifreebuffers) 240 needsbuffer &= ~VFS_BIO_NEED_FREE; 241 wakeup(&needsbuffer); 242 } 243 } 244 245 /* 246 * waitrunningbufspace() 247 * 248 * runningbufspace is a measure of the amount of I/O currently 249 * running. This routine is used in async-write situations to 250 * prevent creating huge backups of pending writes to a device. 251 * Only asynchronous writes are governed by this function. 252 * 253 * Reads will adjust runningbufspace, but will not block based on it. 254 * The read load has a side effect of reducing the allowed write load. 255 * 256 * This does NOT turn an async write into a sync write. It waits 257 * for earlier writes to complete and generally returns before the 258 * caller's write has reached the device. 259 */ 260 static __inline void 261 waitrunningbufspace(void) 262 { 263 while (runningbufspace > hirunningspace) { 264 int s; 265 266 s = splbio(); /* fix race against interrupt/biodone() */ 267 ++runningbufreq; 268 tsleep(&runningbufreq, PVM, "wdrain", 0); 269 splx(s); 270 } 271 } 272 273 /* 274 * vfs_buf_test_cache: 275 * 276 * Called when a buffer is extended. This function clears the B_CACHE 277 * bit if the newly extended portion of the buffer does not contain 278 * valid data. 279 */ 280 static __inline__ 281 void 282 vfs_buf_test_cache(struct buf *bp, 283 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 284 vm_page_t m) 285 { 286 if (bp->b_flags & B_CACHE) { 287 int base = (foff + off) & PAGE_MASK; 288 if (vm_page_is_valid(m, base, size) == 0) 289 bp->b_flags &= ~B_CACHE; 290 } 291 } 292 293 static __inline__ 294 void 295 bd_wakeup(int dirtybuflevel) 296 { 297 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) { 298 bd_request = 1; 299 wakeup(&bd_request); 300 } 301 } 302 303 /* 304 * bd_speedup - speedup the buffer cache flushing code 305 */ 306 307 static __inline__ 308 void 309 bd_speedup(void) 310 { 311 bd_wakeup(1); 312 } 313 314 /* 315 * Initialize buffer headers and related structures. 316 */ 317 318 caddr_t 319 bufhashinit(caddr_t vaddr) 320 { 321 /* first, make a null hash table */ 322 for (bufhashmask = 8; bufhashmask < nbuf / 4; bufhashmask <<= 1) 323 ; 324 bufhashtbl = (void *)vaddr; 325 vaddr = vaddr + sizeof(*bufhashtbl) * bufhashmask; 326 --bufhashmask; 327 return(vaddr); 328 } 329 330 void 331 bufinit(void) 332 { 333 struct buf *bp; 334 int i; 335 336 TAILQ_INIT(&bswlist); 337 LIST_INIT(&invalhash); 338 simple_lock_init(&buftimelock); 339 340 for (i = 0; i <= bufhashmask; i++) 341 LIST_INIT(&bufhashtbl[i]); 342 343 /* next, make a null set of free lists */ 344 for (i = 0; i < BUFFER_QUEUES; i++) 345 TAILQ_INIT(&bufqueues[i]); 346 347 /* finally, initialize each buffer header and stick on empty q */ 348 for (i = 0; i < nbuf; i++) { 349 bp = &buf[i]; 350 bzero(bp, sizeof *bp); 351 bp->b_flags = B_INVAL; /* we're just an empty header */ 352 bp->b_dev = NODEV; 353 bp->b_rcred = NOCRED; 354 bp->b_wcred = NOCRED; 355 bp->b_qindex = QUEUE_EMPTY; 356 bp->b_xflags = 0; 357 LIST_INIT(&bp->b_dep); 358 BUF_LOCKINIT(bp); 359 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 360 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 361 } 362 363 /* 364 * maxbufspace is the absolute maximum amount of buffer space we are 365 * allowed to reserve in KVM and in real terms. The absolute maximum 366 * is nominally used by buf_daemon. hibufspace is the nominal maximum 367 * used by most other processes. The differential is required to 368 * ensure that buf_daemon is able to run when other processes might 369 * be blocked waiting for buffer space. 370 * 371 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 372 * this may result in KVM fragmentation which is not handled optimally 373 * by the system. 374 */ 375 maxbufspace = nbuf * BKVASIZE; 376 hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 377 lobufspace = hibufspace - MAXBSIZE; 378 379 lorunningspace = 512 * 1024; 380 hirunningspace = 1024 * 1024; 381 382 /* 383 * Limit the amount of malloc memory since it is wired permanently into 384 * the kernel space. Even though this is accounted for in the buffer 385 * allocation, we don't want the malloced region to grow uncontrolled. 386 * The malloc scheme improves memory utilization significantly on average 387 * (small) directories. 388 */ 389 maxbufmallocspace = hibufspace / 20; 390 391 /* 392 * Reduce the chance of a deadlock occuring by limiting the number 393 * of delayed-write dirty buffers we allow to stack up. 394 */ 395 hidirtybuffers = nbuf / 4 + 20; 396 numdirtybuffers = 0; 397 /* 398 * To support extreme low-memory systems, make sure hidirtybuffers cannot 399 * eat up all available buffer space. This occurs when our minimum cannot 400 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 401 * BKVASIZE'd (8K) buffers. 402 */ 403 while (hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 404 hidirtybuffers >>= 1; 405 } 406 lodirtybuffers = hidirtybuffers / 2; 407 408 /* 409 * Try to keep the number of free buffers in the specified range, 410 * and give special processes (e.g. like buf_daemon) access to an 411 * emergency reserve. 412 */ 413 lofreebuffers = nbuf / 18 + 5; 414 hifreebuffers = 2 * lofreebuffers; 415 numfreebuffers = nbuf; 416 417 /* 418 * Maximum number of async ops initiated per buf_daemon loop. This is 419 * somewhat of a hack at the moment, we really need to limit ourselves 420 * based on the number of bytes of I/O in-transit that were initiated 421 * from buf_daemon. 422 */ 423 424 bogus_offset = kmem_alloc_pageable(kernel_map, PAGE_SIZE); 425 bogus_page = vm_page_alloc(kernel_object, 426 ((bogus_offset - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 427 VM_ALLOC_NORMAL); 428 cnt.v_wire_count++; 429 430 } 431 432 /* 433 * bfreekva() - free the kva allocation for a buffer. 434 * 435 * Must be called at splbio() or higher as this is the only locking for 436 * buffer_map. 437 * 438 * Since this call frees up buffer space, we call bufspacewakeup(). 439 */ 440 static void 441 bfreekva(struct buf * bp) 442 { 443 if (bp->b_kvasize) { 444 ++buffreekvacnt; 445 vm_map_lock(buffer_map); 446 bufspace -= bp->b_kvasize; 447 vm_map_delete(buffer_map, 448 (vm_offset_t) bp->b_kvabase, 449 (vm_offset_t) bp->b_kvabase + bp->b_kvasize 450 ); 451 vm_map_unlock(buffer_map); 452 bp->b_kvasize = 0; 453 bufspacewakeup(); 454 } 455 } 456 457 /* 458 * bremfree: 459 * 460 * Remove the buffer from the appropriate free list. 461 */ 462 void 463 bremfree(struct buf * bp) 464 { 465 int s = splbio(); 466 int old_qindex = bp->b_qindex; 467 468 if (bp->b_qindex != QUEUE_NONE) { 469 KASSERT(BUF_REFCNT(bp) == 1, ("bremfree: bp %p not locked",bp)); 470 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 471 bp->b_qindex = QUEUE_NONE; 472 } else { 473 if (BUF_REFCNT(bp) <= 1) 474 panic("bremfree: removing a buffer not on a queue"); 475 } 476 477 /* 478 * Fixup numfreebuffers count. If the buffer is invalid or not 479 * delayed-write, and it was on the EMPTY, LRU, or AGE queues, 480 * the buffer was free and we must decrement numfreebuffers. 481 */ 482 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { 483 switch(old_qindex) { 484 case QUEUE_DIRTY: 485 case QUEUE_CLEAN: 486 case QUEUE_EMPTY: 487 case QUEUE_EMPTYKVA: 488 --numfreebuffers; 489 break; 490 default: 491 break; 492 } 493 } 494 splx(s); 495 } 496 497 498 /* 499 * Get a buffer with the specified data. Look in the cache first. We 500 * must clear B_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 501 * is set, the buffer is valid and we do not have to do anything ( see 502 * getblk() ). 503 */ 504 int 505 bread(struct vnode * vp, daddr_t blkno, int size, struct ucred * cred, 506 struct buf ** bpp) 507 { 508 struct buf *bp; 509 510 bp = getblk(vp, blkno, size, 0, 0); 511 *bpp = bp; 512 513 /* if not found in cache, do some I/O */ 514 if ((bp->b_flags & B_CACHE) == 0) { 515 if (curproc != NULL) 516 curproc->p_stats->p_ru.ru_inblock++; 517 KASSERT(!(bp->b_flags & B_ASYNC), ("bread: illegal async bp %p", bp)); 518 bp->b_flags |= B_READ; 519 bp->b_flags &= ~(B_ERROR | B_INVAL); 520 if (bp->b_rcred == NOCRED) { 521 if (cred != NOCRED) 522 crhold(cred); 523 bp->b_rcred = cred; 524 } 525 vfs_busy_pages(bp, 0); 526 VOP_STRATEGY(vp, bp); 527 return (biowait(bp)); 528 } 529 return (0); 530 } 531 532 /* 533 * Operates like bread, but also starts asynchronous I/O on 534 * read-ahead blocks. We must clear B_ERROR and B_INVAL prior 535 * to initiating I/O . If B_CACHE is set, the buffer is valid 536 * and we do not have to do anything. 537 */ 538 int 539 breadn(struct vnode * vp, daddr_t blkno, int size, 540 daddr_t * rablkno, int *rabsize, 541 int cnt, struct ucred * cred, struct buf ** bpp) 542 { 543 struct buf *bp, *rabp; 544 int i; 545 int rv = 0, readwait = 0; 546 547 *bpp = bp = getblk(vp, blkno, size, 0, 0); 548 549 /* if not found in cache, do some I/O */ 550 if ((bp->b_flags & B_CACHE) == 0) { 551 if (curproc != NULL) 552 curproc->p_stats->p_ru.ru_inblock++; 553 bp->b_flags |= B_READ; 554 bp->b_flags &= ~(B_ERROR | B_INVAL); 555 if (bp->b_rcred == NOCRED) { 556 if (cred != NOCRED) 557 crhold(cred); 558 bp->b_rcred = cred; 559 } 560 vfs_busy_pages(bp, 0); 561 VOP_STRATEGY(vp, bp); 562 ++readwait; 563 } 564 565 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 566 if (inmem(vp, *rablkno)) 567 continue; 568 rabp = getblk(vp, *rablkno, *rabsize, 0, 0); 569 570 if ((rabp->b_flags & B_CACHE) == 0) { 571 if (curproc != NULL) 572 curproc->p_stats->p_ru.ru_inblock++; 573 rabp->b_flags |= B_READ | B_ASYNC; 574 rabp->b_flags &= ~(B_ERROR | B_INVAL); 575 if (rabp->b_rcred == NOCRED) { 576 if (cred != NOCRED) 577 crhold(cred); 578 rabp->b_rcred = cred; 579 } 580 vfs_busy_pages(rabp, 0); 581 BUF_KERNPROC(rabp); 582 VOP_STRATEGY(vp, rabp); 583 } else { 584 brelse(rabp); 585 } 586 } 587 588 if (readwait) { 589 rv = biowait(bp); 590 } 591 return (rv); 592 } 593 594 /* 595 * Write, release buffer on completion. (Done by iodone 596 * if async). Do not bother writing anything if the buffer 597 * is invalid. 598 * 599 * Note that we set B_CACHE here, indicating that buffer is 600 * fully valid and thus cacheable. This is true even of NFS 601 * now so we set it generally. This could be set either here 602 * or in biodone() since the I/O is synchronous. We put it 603 * here. 604 */ 605 int 606 bwrite(struct buf * bp) 607 { 608 int oldflags, s; 609 struct buf *newbp; 610 611 if (bp->b_flags & B_INVAL) { 612 brelse(bp); 613 return (0); 614 } 615 616 oldflags = bp->b_flags; 617 618 if (BUF_REFCNT(bp) == 0) 619 panic("bwrite: buffer is not busy???"); 620 s = splbio(); 621 /* 622 * If a background write is already in progress, delay 623 * writing this block if it is asynchronous. Otherwise 624 * wait for the background write to complete. 625 */ 626 if (bp->b_xflags & BX_BKGRDINPROG) { 627 if (bp->b_flags & B_ASYNC) { 628 splx(s); 629 bdwrite(bp); 630 return (0); 631 } 632 bp->b_xflags |= BX_BKGRDWAIT; 633 tsleep(&bp->b_xflags, PRIBIO, "biord", 0); 634 if (bp->b_xflags & BX_BKGRDINPROG) 635 panic("bwrite: still writing"); 636 } 637 638 /* Mark the buffer clean */ 639 bundirty(bp); 640 641 /* 642 * If this buffer is marked for background writing and we 643 * do not have to wait for it, make a copy and write the 644 * copy so as to leave this buffer ready for further use. 645 * 646 * This optimization eats a lot of memory. If we have a page 647 * or buffer shortfull we can't do it. 648 */ 649 if ((bp->b_xflags & BX_BKGRDWRITE) && 650 (bp->b_flags & B_ASYNC) && 651 !vm_page_count_severe() && 652 !buf_dirty_count_severe()) { 653 if (bp->b_flags & B_CALL) 654 panic("bwrite: need chained iodone"); 655 656 /* get a new block */ 657 newbp = geteblk(bp->b_bufsize); 658 659 /* set it to be identical to the old block */ 660 memcpy(newbp->b_data, bp->b_data, bp->b_bufsize); 661 bgetvp(bp->b_vp, newbp); 662 newbp->b_lblkno = bp->b_lblkno; 663 newbp->b_blkno = bp->b_blkno; 664 newbp->b_offset = bp->b_offset; 665 newbp->b_iodone = vfs_backgroundwritedone; 666 newbp->b_flags |= B_ASYNC | B_CALL; 667 newbp->b_flags &= ~B_INVAL; 668 669 /* move over the dependencies */ 670 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_movedeps) 671 (*bioops.io_movedeps)(bp, newbp); 672 673 /* 674 * Initiate write on the copy, release the original to 675 * the B_LOCKED queue so that it cannot go away until 676 * the background write completes. If not locked it could go 677 * away and then be reconstituted while it was being written. 678 * If the reconstituted buffer were written, we could end up 679 * with two background copies being written at the same time. 680 */ 681 bp->b_xflags |= BX_BKGRDINPROG; 682 bp->b_flags |= B_LOCKED; 683 bqrelse(bp); 684 bp = newbp; 685 } 686 687 bp->b_flags &= ~(B_READ | B_DONE | B_ERROR); 688 bp->b_flags |= B_WRITEINPROG | B_CACHE; 689 690 bp->b_vp->v_numoutput++; 691 vfs_busy_pages(bp, 1); 692 693 /* 694 * Normal bwrites pipeline writes 695 */ 696 bp->b_runningbufspace = bp->b_bufsize; 697 runningbufspace += bp->b_runningbufspace; 698 699 if (curproc != NULL) 700 curproc->p_stats->p_ru.ru_oublock++; 701 splx(s); 702 if (oldflags & B_ASYNC) 703 BUF_KERNPROC(bp); 704 VOP_STRATEGY(bp->b_vp, bp); 705 706 if ((oldflags & B_ASYNC) == 0) { 707 int rtval = biowait(bp); 708 brelse(bp); 709 return (rtval); 710 } else if ((oldflags & B_NOWDRAIN) == 0) { 711 /* 712 * don't allow the async write to saturate the I/O 713 * system. Deadlocks can occur only if a device strategy 714 * routine (like in VN) turns around and issues another 715 * high-level write, in which case B_NOWDRAIN is expected 716 * to be set. Otherwise we will not deadlock here because 717 * we are blocking waiting for I/O that is already in-progress 718 * to complete. 719 */ 720 waitrunningbufspace(); 721 } 722 723 return (0); 724 } 725 726 /* 727 * Complete a background write started from bwrite. 728 */ 729 static void 730 vfs_backgroundwritedone(bp) 731 struct buf *bp; 732 { 733 struct buf *origbp; 734 735 /* 736 * Find the original buffer that we are writing. 737 */ 738 if ((origbp = gbincore(bp->b_vp, bp->b_lblkno)) == NULL) 739 panic("backgroundwritedone: lost buffer"); 740 /* 741 * Process dependencies then return any unfinished ones. 742 */ 743 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_complete) 744 (*bioops.io_complete)(bp); 745 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_movedeps) 746 (*bioops.io_movedeps)(bp, origbp); 747 /* 748 * Clear the BX_BKGRDINPROG flag in the original buffer 749 * and awaken it if it is waiting for the write to complete. 750 * If BX_BKGRDINPROG is not set in the original buffer it must 751 * have been released and re-instantiated - which is not legal. 752 */ 753 KASSERT((origbp->b_xflags & BX_BKGRDINPROG), ("backgroundwritedone: lost buffer2")); 754 origbp->b_xflags &= ~BX_BKGRDINPROG; 755 if (origbp->b_xflags & BX_BKGRDWAIT) { 756 origbp->b_xflags &= ~BX_BKGRDWAIT; 757 wakeup(&origbp->b_xflags); 758 } 759 /* 760 * Clear the B_LOCKED flag and remove it from the locked 761 * queue if it currently resides there. 762 */ 763 origbp->b_flags &= ~B_LOCKED; 764 if (BUF_LOCK(origbp, LK_EXCLUSIVE | LK_NOWAIT) == 0) { 765 bremfree(origbp); 766 bqrelse(origbp); 767 } 768 /* 769 * This buffer is marked B_NOCACHE, so when it is released 770 * by biodone, it will be tossed. We mark it with B_READ 771 * to avoid biodone doing a second vwakeup. 772 */ 773 bp->b_flags |= B_NOCACHE | B_READ; 774 bp->b_flags &= ~(B_CACHE | B_CALL | B_DONE); 775 bp->b_iodone = 0; 776 biodone(bp); 777 } 778 779 /* 780 * Delayed write. (Buffer is marked dirty). Do not bother writing 781 * anything if the buffer is marked invalid. 782 * 783 * Note that since the buffer must be completely valid, we can safely 784 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 785 * biodone() in order to prevent getblk from writing the buffer 786 * out synchronously. 787 */ 788 void 789 bdwrite(struct buf * bp) 790 { 791 if (BUF_REFCNT(bp) == 0) 792 panic("bdwrite: buffer is not busy"); 793 794 if (bp->b_flags & B_INVAL) { 795 brelse(bp); 796 return; 797 } 798 bdirty(bp); 799 800 /* 801 * Set B_CACHE, indicating that the buffer is fully valid. This is 802 * true even of NFS now. 803 */ 804 bp->b_flags |= B_CACHE; 805 806 /* 807 * This bmap keeps the system from needing to do the bmap later, 808 * perhaps when the system is attempting to do a sync. Since it 809 * is likely that the indirect block -- or whatever other datastructure 810 * that the filesystem needs is still in memory now, it is a good 811 * thing to do this. Note also, that if the pageout daemon is 812 * requesting a sync -- there might not be enough memory to do 813 * the bmap then... So, this is important to do. 814 */ 815 if (bp->b_lblkno == bp->b_blkno) { 816 VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 817 } 818 819 /* 820 * Set the *dirty* buffer range based upon the VM system dirty pages. 821 */ 822 vfs_setdirty(bp); 823 824 /* 825 * We need to do this here to satisfy the vnode_pager and the 826 * pageout daemon, so that it thinks that the pages have been 827 * "cleaned". Note that since the pages are in a delayed write 828 * buffer -- the VFS layer "will" see that the pages get written 829 * out on the next sync, or perhaps the cluster will be completed. 830 */ 831 vfs_clean_pages(bp); 832 bqrelse(bp); 833 834 /* 835 * Wakeup the buffer flushing daemon if we have a lot of dirty 836 * buffers (midpoint between our recovery point and our stall 837 * point). 838 */ 839 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 840 841 /* 842 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 843 * due to the softdep code. 844 */ 845 } 846 847 /* 848 * bdirty: 849 * 850 * Turn buffer into delayed write request. We must clear B_READ and 851 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 852 * itself to properly update it in the dirty/clean lists. We mark it 853 * B_DONE to ensure that any asynchronization of the buffer properly 854 * clears B_DONE ( else a panic will occur later ). 855 * 856 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 857 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 858 * should only be called if the buffer is known-good. 859 * 860 * Since the buffer is not on a queue, we do not update the numfreebuffers 861 * count. 862 * 863 * Must be called at splbio(). 864 * The buffer must be on QUEUE_NONE. 865 */ 866 void 867 bdirty(bp) 868 struct buf *bp; 869 { 870 KASSERT(bp->b_qindex == QUEUE_NONE, ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 871 bp->b_flags &= ~(B_READ|B_RELBUF); 872 873 if ((bp->b_flags & B_DELWRI) == 0) { 874 bp->b_flags |= B_DONE | B_DELWRI; 875 reassignbuf(bp, bp->b_vp); 876 ++numdirtybuffers; 877 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 878 } 879 } 880 881 /* 882 * bundirty: 883 * 884 * Clear B_DELWRI for buffer. 885 * 886 * Since the buffer is not on a queue, we do not update the numfreebuffers 887 * count. 888 * 889 * Must be called at splbio(). 890 * The buffer must be on QUEUE_NONE. 891 */ 892 893 void 894 bundirty(bp) 895 struct buf *bp; 896 { 897 KASSERT(bp->b_qindex == QUEUE_NONE, ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 898 899 if (bp->b_flags & B_DELWRI) { 900 bp->b_flags &= ~B_DELWRI; 901 reassignbuf(bp, bp->b_vp); 902 --numdirtybuffers; 903 numdirtywakeup(lodirtybuffers); 904 } 905 /* 906 * Since it is now being written, we can clear its deferred write flag. 907 */ 908 bp->b_flags &= ~B_DEFERRED; 909 } 910 911 /* 912 * bawrite: 913 * 914 * Asynchronous write. Start output on a buffer, but do not wait for 915 * it to complete. The buffer is released when the output completes. 916 * 917 * bwrite() ( or the VOP routine anyway ) is responsible for handling 918 * B_INVAL buffers. Not us. 919 */ 920 void 921 bawrite(struct buf * bp) 922 { 923 bp->b_flags |= B_ASYNC; 924 (void) VOP_BWRITE(bp->b_vp, bp); 925 } 926 927 /* 928 * bowrite: 929 * 930 * Ordered write. Start output on a buffer, and flag it so that the 931 * device will write it in the order it was queued. The buffer is 932 * released when the output completes. bwrite() ( or the VOP routine 933 * anyway ) is responsible for handling B_INVAL buffers. 934 */ 935 int 936 bowrite(struct buf * bp) 937 { 938 bp->b_flags |= B_ORDERED | B_ASYNC; 939 return (VOP_BWRITE(bp->b_vp, bp)); 940 } 941 942 /* 943 * bwillwrite: 944 * 945 * Called prior to the locking of any vnodes when we are expecting to 946 * write. We do not want to starve the buffer cache with too many 947 * dirty buffers so we block here. By blocking prior to the locking 948 * of any vnodes we attempt to avoid the situation where a locked vnode 949 * prevents the various system daemons from flushing related buffers. 950 */ 951 952 void 953 bwillwrite(void) 954 { 955 if (numdirtybuffers >= hidirtybuffers) { 956 int s; 957 958 s = splbio(); 959 while (numdirtybuffers >= hidirtybuffers) { 960 bd_wakeup(1); 961 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH; 962 tsleep(&needsbuffer, (PRIBIO + 4), "flswai", 0); 963 } 964 splx(s); 965 } 966 } 967 968 /* 969 * Return true if we have too many dirty buffers. 970 */ 971 int 972 buf_dirty_count_severe(void) 973 { 974 return(numdirtybuffers >= hidirtybuffers); 975 } 976 977 /* 978 * brelse: 979 * 980 * Release a busy buffer and, if requested, free its resources. The 981 * buffer will be stashed in the appropriate bufqueue[] allowing it 982 * to be accessed later as a cache entity or reused for other purposes. 983 */ 984 void 985 brelse(struct buf * bp) 986 { 987 int s; 988 989 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 990 991 s = splbio(); 992 993 if (bp->b_flags & B_LOCKED) 994 bp->b_flags &= ~B_ERROR; 995 996 if ((bp->b_flags & (B_READ | B_ERROR | B_INVAL)) == B_ERROR) { 997 /* 998 * Failed write, redirty. Must clear B_ERROR to prevent 999 * pages from being scrapped. If B_INVAL is set then 1000 * this case is not run and the next case is run to 1001 * destroy the buffer. B_INVAL can occur if the buffer 1002 * is outside the range supported by the underlying device. 1003 */ 1004 bp->b_flags &= ~B_ERROR; 1005 bdirty(bp); 1006 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR | B_FREEBUF)) || 1007 (bp->b_bufsize <= 0)) { 1008 /* 1009 * Either a failed I/O or we were asked to free or not 1010 * cache the buffer. 1011 */ 1012 bp->b_flags |= B_INVAL; 1013 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_deallocate) 1014 (*bioops.io_deallocate)(bp); 1015 if (bp->b_flags & B_DELWRI) { 1016 --numdirtybuffers; 1017 numdirtywakeup(lodirtybuffers); 1018 } 1019 bp->b_flags &= ~(B_DELWRI | B_CACHE | B_FREEBUF); 1020 if ((bp->b_flags & B_VMIO) == 0) { 1021 if (bp->b_bufsize) 1022 allocbuf(bp, 0); 1023 if (bp->b_vp) 1024 brelvp(bp); 1025 } 1026 } 1027 1028 /* 1029 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1030 * is called with B_DELWRI set, the underlying pages may wind up 1031 * getting freed causing a previous write (bdwrite()) to get 'lost' 1032 * because pages associated with a B_DELWRI bp are marked clean. 1033 * 1034 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1035 * if B_DELWRI is set. 1036 * 1037 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1038 * on pages to return pages to the VM page queues. 1039 */ 1040 if (bp->b_flags & B_DELWRI) 1041 bp->b_flags &= ~B_RELBUF; 1042 else if (vm_page_count_severe() && !(bp->b_xflags & BX_BKGRDINPROG)) 1043 bp->b_flags |= B_RELBUF; 1044 1045 /* 1046 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1047 * constituted, not even NFS buffers now. Two flags effect this. If 1048 * B_INVAL, the struct buf is invalidated but the VM object is kept 1049 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1050 * 1051 * If B_ERROR or B_NOCACHE is set, pages in the VM object will be 1052 * invalidated. B_ERROR cannot be set for a failed write unless the 1053 * buffer is also B_INVAL because it hits the re-dirtying code above. 1054 * 1055 * Normally we can do this whether a buffer is B_DELWRI or not. If 1056 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1057 * the commit state and we cannot afford to lose the buffer. If the 1058 * buffer has a background write in progress, we need to keep it 1059 * around to prevent it from being reconstituted and starting a second 1060 * background write. 1061 */ 1062 if ((bp->b_flags & B_VMIO) 1063 && !(bp->b_vp->v_tag == VT_NFS && 1064 !vn_isdisk(bp->b_vp, NULL) && 1065 (bp->b_flags & B_DELWRI)) 1066 ) { 1067 1068 int i, j, resid; 1069 vm_page_t m; 1070 off_t foff; 1071 vm_pindex_t poff; 1072 vm_object_t obj; 1073 struct vnode *vp; 1074 1075 vp = bp->b_vp; 1076 1077 /* 1078 * Get the base offset and length of the buffer. Note that 1079 * in the VMIO case if the buffer block size is not 1080 * page-aligned then b_data pointer may not be page-aligned. 1081 * But our b_pages[] array *IS* page aligned. 1082 * 1083 * block sizes less then DEV_BSIZE (usually 512) are not 1084 * supported due to the page granularity bits (m->valid, 1085 * m->dirty, etc...). 1086 * 1087 * See man buf(9) for more information 1088 */ 1089 1090 resid = bp->b_bufsize; 1091 foff = bp->b_offset; 1092 1093 for (i = 0; i < bp->b_npages; i++) { 1094 m = bp->b_pages[i]; 1095 vm_page_flag_clear(m, PG_ZERO); 1096 /* 1097 * If we hit a bogus page, fixup *all* of them 1098 * now. 1099 */ 1100 if (m == bogus_page) { 1101 VOP_GETVOBJECT(vp, &obj); 1102 poff = OFF_TO_IDX(bp->b_offset); 1103 1104 for (j = i; j < bp->b_npages; j++) { 1105 vm_page_t mtmp; 1106 1107 mtmp = bp->b_pages[j]; 1108 if (mtmp == bogus_page) { 1109 mtmp = vm_page_lookup(obj, poff + j); 1110 if (!mtmp) { 1111 panic("brelse: page missing\n"); 1112 } 1113 bp->b_pages[j] = mtmp; 1114 } 1115 } 1116 1117 if ((bp->b_flags & B_INVAL) == 0) { 1118 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 1119 } 1120 m = bp->b_pages[i]; 1121 } 1122 if (bp->b_flags & (B_NOCACHE|B_ERROR)) { 1123 int poffset = foff & PAGE_MASK; 1124 int presid = resid > (PAGE_SIZE - poffset) ? 1125 (PAGE_SIZE - poffset) : resid; 1126 1127 KASSERT(presid >= 0, ("brelse: extra page")); 1128 vm_page_set_invalid(m, poffset, presid); 1129 } 1130 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1131 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1132 } 1133 1134 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1135 vfs_vmio_release(bp); 1136 1137 } else if (bp->b_flags & B_VMIO) { 1138 1139 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1140 vfs_vmio_release(bp); 1141 1142 } 1143 1144 if (bp->b_qindex != QUEUE_NONE) 1145 panic("brelse: free buffer onto another queue???"); 1146 if (BUF_REFCNT(bp) > 1) { 1147 /* Temporary panic to verify exclusive locking */ 1148 /* This panic goes away when we allow shared refs */ 1149 panic("brelse: multiple refs"); 1150 /* do not release to free list */ 1151 BUF_UNLOCK(bp); 1152 splx(s); 1153 return; 1154 } 1155 1156 /* enqueue */ 1157 1158 /* buffers with no memory */ 1159 if (bp->b_bufsize == 0) { 1160 bp->b_flags |= B_INVAL; 1161 bp->b_xflags &= ~BX_BKGRDWRITE; 1162 if (bp->b_xflags & BX_BKGRDINPROG) 1163 panic("losing buffer 1"); 1164 if (bp->b_kvasize) { 1165 bp->b_qindex = QUEUE_EMPTYKVA; 1166 } else { 1167 bp->b_qindex = QUEUE_EMPTY; 1168 } 1169 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1170 LIST_REMOVE(bp, b_hash); 1171 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1172 bp->b_dev = NODEV; 1173 /* buffers with junk contents */ 1174 } else if (bp->b_flags & (B_ERROR | B_INVAL | B_NOCACHE | B_RELBUF)) { 1175 bp->b_flags |= B_INVAL; 1176 bp->b_xflags &= ~BX_BKGRDWRITE; 1177 if (bp->b_xflags & BX_BKGRDINPROG) 1178 panic("losing buffer 2"); 1179 bp->b_qindex = QUEUE_CLEAN; 1180 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1181 LIST_REMOVE(bp, b_hash); 1182 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1183 bp->b_dev = NODEV; 1184 1185 /* buffers that are locked */ 1186 } else if (bp->b_flags & B_LOCKED) { 1187 bp->b_qindex = QUEUE_LOCKED; 1188 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LOCKED], bp, b_freelist); 1189 1190 /* remaining buffers */ 1191 } else { 1192 switch(bp->b_flags & (B_DELWRI|B_AGE)) { 1193 case B_DELWRI | B_AGE: 1194 bp->b_qindex = QUEUE_DIRTY; 1195 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_DIRTY], bp, b_freelist); 1196 break; 1197 case B_DELWRI: 1198 bp->b_qindex = QUEUE_DIRTY; 1199 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist); 1200 break; 1201 case B_AGE: 1202 bp->b_qindex = QUEUE_CLEAN; 1203 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1204 break; 1205 default: 1206 bp->b_qindex = QUEUE_CLEAN; 1207 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1208 break; 1209 } 1210 } 1211 1212 /* 1213 * If B_INVAL, clear B_DELWRI. We've already placed the buffer 1214 * on the correct queue. 1215 */ 1216 if ((bp->b_flags & (B_INVAL|B_DELWRI)) == (B_INVAL|B_DELWRI)) 1217 bundirty(bp); 1218 1219 /* 1220 * Fixup numfreebuffers count. The bp is on an appropriate queue 1221 * unless locked. We then bump numfreebuffers if it is not B_DELWRI. 1222 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1223 * if B_INVAL is set ). 1224 */ 1225 1226 if ((bp->b_flags & B_LOCKED) == 0 && !(bp->b_flags & B_DELWRI)) 1227 bufcountwakeup(); 1228 1229 /* 1230 * Something we can maybe free or reuse 1231 */ 1232 if (bp->b_bufsize || bp->b_kvasize) 1233 bufspacewakeup(); 1234 1235 /* unlock */ 1236 BUF_UNLOCK(bp); 1237 bp->b_flags &= ~(B_ORDERED | B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | 1238 B_DIRECT | B_NOWDRAIN); 1239 splx(s); 1240 } 1241 1242 /* 1243 * Release a buffer back to the appropriate queue but do not try to free 1244 * it. The buffer is expected to be used again soon. 1245 * 1246 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1247 * biodone() to requeue an async I/O on completion. It is also used when 1248 * known good buffers need to be requeued but we think we may need the data 1249 * again soon. 1250 * 1251 * XXX we should be able to leave the B_RELBUF hint set on completion. 1252 */ 1253 void 1254 bqrelse(struct buf * bp) 1255 { 1256 int s; 1257 1258 s = splbio(); 1259 1260 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1261 1262 if (bp->b_qindex != QUEUE_NONE) 1263 panic("bqrelse: free buffer onto another queue???"); 1264 if (BUF_REFCNT(bp) > 1) { 1265 /* do not release to free list */ 1266 panic("bqrelse: multiple refs"); 1267 BUF_UNLOCK(bp); 1268 splx(s); 1269 return; 1270 } 1271 if (bp->b_flags & B_LOCKED) { 1272 bp->b_flags &= ~B_ERROR; 1273 bp->b_qindex = QUEUE_LOCKED; 1274 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LOCKED], bp, b_freelist); 1275 /* buffers with stale but valid contents */ 1276 } else if (bp->b_flags & B_DELWRI) { 1277 bp->b_qindex = QUEUE_DIRTY; 1278 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist); 1279 } else if (vm_page_count_severe()) { 1280 /* 1281 * We are too low on memory, we have to try to free the 1282 * buffer (most importantly: the wired pages making up its 1283 * backing store) *now*. 1284 */ 1285 splx(s); 1286 brelse(bp); 1287 return; 1288 } else { 1289 bp->b_qindex = QUEUE_CLEAN; 1290 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1291 } 1292 1293 if ((bp->b_flags & B_LOCKED) == 0 && 1294 ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI))) { 1295 bufcountwakeup(); 1296 } 1297 1298 /* 1299 * Something we can maybe free or reuse. 1300 */ 1301 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1302 bufspacewakeup(); 1303 1304 /* unlock */ 1305 BUF_UNLOCK(bp); 1306 bp->b_flags &= ~(B_ORDERED | B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1307 splx(s); 1308 } 1309 1310 static void 1311 vfs_vmio_release(bp) 1312 struct buf *bp; 1313 { 1314 int i, s; 1315 vm_page_t m; 1316 1317 s = splvm(); 1318 for (i = 0; i < bp->b_npages; i++) { 1319 m = bp->b_pages[i]; 1320 bp->b_pages[i] = NULL; 1321 /* 1322 * In order to keep page LRU ordering consistent, put 1323 * everything on the inactive queue. 1324 */ 1325 vm_page_unwire(m, 0); 1326 /* 1327 * We don't mess with busy pages, it is 1328 * the responsibility of the process that 1329 * busied the pages to deal with them. 1330 */ 1331 if ((m->flags & PG_BUSY) || (m->busy != 0)) 1332 continue; 1333 1334 if (m->wire_count == 0) { 1335 vm_page_flag_clear(m, PG_ZERO); 1336 /* 1337 * Might as well free the page if we can and it has 1338 * no valid data. We also free the page if the 1339 * buffer was used for direct I/O. 1340 */ 1341 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && m->hold_count == 0) { 1342 vm_page_busy(m); 1343 vm_page_protect(m, VM_PROT_NONE); 1344 vm_page_free(m); 1345 } else if (bp->b_flags & B_DIRECT) { 1346 vm_page_try_to_free(m); 1347 } else if (vm_page_count_severe()) { 1348 vm_page_try_to_cache(m); 1349 } 1350 } 1351 } 1352 splx(s); 1353 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages); 1354 if (bp->b_bufsize) { 1355 bufspacewakeup(); 1356 bp->b_bufsize = 0; 1357 } 1358 bp->b_npages = 0; 1359 bp->b_flags &= ~B_VMIO; 1360 if (bp->b_vp) 1361 brelvp(bp); 1362 } 1363 1364 /* 1365 * Check to see if a block is currently memory resident. 1366 */ 1367 struct buf * 1368 gbincore(struct vnode * vp, daddr_t blkno) 1369 { 1370 struct buf *bp; 1371 struct bufhashhdr *bh; 1372 1373 bh = bufhash(vp, blkno); 1374 1375 /* Search hash chain */ 1376 LIST_FOREACH(bp, bh, b_hash) { 1377 /* hit */ 1378 if (bp->b_vp == vp && bp->b_lblkno == blkno && 1379 (bp->b_flags & B_INVAL) == 0) { 1380 break; 1381 } 1382 } 1383 return (bp); 1384 } 1385 1386 /* 1387 * vfs_bio_awrite: 1388 * 1389 * Implement clustered async writes for clearing out B_DELWRI buffers. 1390 * This is much better then the old way of writing only one buffer at 1391 * a time. Note that we may not be presented with the buffers in the 1392 * correct order, so we search for the cluster in both directions. 1393 */ 1394 int 1395 vfs_bio_awrite(struct buf * bp) 1396 { 1397 int i; 1398 int j; 1399 daddr_t lblkno = bp->b_lblkno; 1400 struct vnode *vp = bp->b_vp; 1401 int s; 1402 int ncl; 1403 struct buf *bpa; 1404 int nwritten; 1405 int size; 1406 int maxcl; 1407 1408 s = splbio(); 1409 /* 1410 * right now we support clustered writing only to regular files. If 1411 * we find a clusterable block we could be in the middle of a cluster 1412 * rather then at the beginning. 1413 */ 1414 if ((vp->v_type == VREG) && 1415 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1416 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1417 1418 size = vp->v_mount->mnt_stat.f_iosize; 1419 maxcl = MAXPHYS / size; 1420 1421 for (i = 1; i < maxcl; i++) { 1422 if ((bpa = gbincore(vp, lblkno + i)) && 1423 BUF_REFCNT(bpa) == 0 && 1424 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == 1425 (B_DELWRI | B_CLUSTEROK)) && 1426 (bpa->b_bufsize == size)) { 1427 if ((bpa->b_blkno == bpa->b_lblkno) || 1428 (bpa->b_blkno != 1429 bp->b_blkno + ((i * size) >> DEV_BSHIFT))) 1430 break; 1431 } else { 1432 break; 1433 } 1434 } 1435 for (j = 1; i + j <= maxcl && j <= lblkno; j++) { 1436 if ((bpa = gbincore(vp, lblkno - j)) && 1437 BUF_REFCNT(bpa) == 0 && 1438 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == 1439 (B_DELWRI | B_CLUSTEROK)) && 1440 (bpa->b_bufsize == size)) { 1441 if ((bpa->b_blkno == bpa->b_lblkno) || 1442 (bpa->b_blkno != 1443 bp->b_blkno - ((j * size) >> DEV_BSHIFT))) 1444 break; 1445 } else { 1446 break; 1447 } 1448 } 1449 --j; 1450 ncl = i + j; 1451 /* 1452 * this is a possible cluster write 1453 */ 1454 if (ncl != 1) { 1455 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl); 1456 splx(s); 1457 return nwritten; 1458 } 1459 } 1460 1461 BUF_LOCK(bp, LK_EXCLUSIVE); 1462 bremfree(bp); 1463 bp->b_flags |= B_ASYNC; 1464 1465 splx(s); 1466 /* 1467 * default (old) behavior, writing out only one block 1468 * 1469 * XXX returns b_bufsize instead of b_bcount for nwritten? 1470 */ 1471 nwritten = bp->b_bufsize; 1472 (void) VOP_BWRITE(bp->b_vp, bp); 1473 1474 return nwritten; 1475 } 1476 1477 /* 1478 * getnewbuf: 1479 * 1480 * Find and initialize a new buffer header, freeing up existing buffers 1481 * in the bufqueues as necessary. The new buffer is returned locked. 1482 * 1483 * Important: B_INVAL is not set. If the caller wishes to throw the 1484 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1485 * 1486 * We block if: 1487 * We have insufficient buffer headers 1488 * We have insufficient buffer space 1489 * buffer_map is too fragmented ( space reservation fails ) 1490 * If we have to flush dirty buffers ( but we try to avoid this ) 1491 * 1492 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1493 * Instead we ask the buf daemon to do it for us. We attempt to 1494 * avoid piecemeal wakeups of the pageout daemon. 1495 */ 1496 1497 static struct buf * 1498 getnewbuf(int slpflag, int slptimeo, int size, int maxsize) 1499 { 1500 struct buf *bp; 1501 struct buf *nbp; 1502 int defrag = 0; 1503 int nqindex; 1504 static int flushingbufs; 1505 1506 /* 1507 * We can't afford to block since we might be holding a vnode lock, 1508 * which may prevent system daemons from running. We deal with 1509 * low-memory situations by proactively returning memory and running 1510 * async I/O rather then sync I/O. 1511 */ 1512 1513 ++getnewbufcalls; 1514 --getnewbufrestarts; 1515 restart: 1516 ++getnewbufrestarts; 1517 1518 /* 1519 * Setup for scan. If we do not have enough free buffers, 1520 * we setup a degenerate case that immediately fails. Note 1521 * that if we are specially marked process, we are allowed to 1522 * dip into our reserves. 1523 * 1524 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 1525 * 1526 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 1527 * However, there are a number of cases (defragging, reusing, ...) 1528 * where we cannot backup. 1529 */ 1530 nqindex = QUEUE_EMPTYKVA; 1531 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 1532 1533 if (nbp == NULL) { 1534 /* 1535 * If no EMPTYKVA buffers and we are either 1536 * defragging or reusing, locate a CLEAN buffer 1537 * to free or reuse. If bufspace useage is low 1538 * skip this step so we can allocate a new buffer. 1539 */ 1540 if (defrag || bufspace >= lobufspace) { 1541 nqindex = QUEUE_CLEAN; 1542 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 1543 } 1544 1545 /* 1546 * If we could not find or were not allowed to reuse a 1547 * CLEAN buffer, check to see if it is ok to use an EMPTY 1548 * buffer. We can only use an EMPTY buffer if allocating 1549 * its KVA would not otherwise run us out of buffer space. 1550 */ 1551 if (nbp == NULL && defrag == 0 && 1552 bufspace + maxsize < hibufspace) { 1553 nqindex = QUEUE_EMPTY; 1554 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1555 } 1556 } 1557 1558 /* 1559 * Run scan, possibly freeing data and/or kva mappings on the fly 1560 * depending. 1561 */ 1562 1563 while ((bp = nbp) != NULL) { 1564 int qindex = nqindex; 1565 1566 /* 1567 * Calculate next bp ( we can only use it if we do not block 1568 * or do other fancy things ). 1569 */ 1570 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 1571 switch(qindex) { 1572 case QUEUE_EMPTY: 1573 nqindex = QUEUE_EMPTYKVA; 1574 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]))) 1575 break; 1576 /* fall through */ 1577 case QUEUE_EMPTYKVA: 1578 nqindex = QUEUE_CLEAN; 1579 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]))) 1580 break; 1581 /* fall through */ 1582 case QUEUE_CLEAN: 1583 /* 1584 * nbp is NULL. 1585 */ 1586 break; 1587 } 1588 } 1589 1590 /* 1591 * Sanity Checks 1592 */ 1593 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp)); 1594 1595 /* 1596 * Note: we no longer distinguish between VMIO and non-VMIO 1597 * buffers. 1598 */ 1599 1600 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); 1601 1602 /* 1603 * If we are defragging then we need a buffer with 1604 * b_kvasize != 0. XXX this situation should no longer 1605 * occur, if defrag is non-zero the buffer's b_kvasize 1606 * should also be non-zero at this point. XXX 1607 */ 1608 if (defrag && bp->b_kvasize == 0) { 1609 printf("Warning: defrag empty buffer %p\n", bp); 1610 continue; 1611 } 1612 1613 /* 1614 * Start freeing the bp. This is somewhat involved. nbp 1615 * remains valid only for QUEUE_EMPTY[KVA] bp's. 1616 */ 1617 1618 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) 1619 panic("getnewbuf: locked buf"); 1620 bremfree(bp); 1621 1622 if (qindex == QUEUE_CLEAN) { 1623 if (bp->b_flags & B_VMIO) { 1624 bp->b_flags &= ~B_ASYNC; 1625 vfs_vmio_release(bp); 1626 } 1627 if (bp->b_vp) 1628 brelvp(bp); 1629 } 1630 1631 /* 1632 * NOTE: nbp is now entirely invalid. We can only restart 1633 * the scan from this point on. 1634 * 1635 * Get the rest of the buffer freed up. b_kva* is still 1636 * valid after this operation. 1637 */ 1638 1639 if (bp->b_rcred != NOCRED) { 1640 crfree(bp->b_rcred); 1641 bp->b_rcred = NOCRED; 1642 } 1643 if (bp->b_wcred != NOCRED) { 1644 crfree(bp->b_wcred); 1645 bp->b_wcred = NOCRED; 1646 } 1647 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_deallocate) 1648 (*bioops.io_deallocate)(bp); 1649 if (bp->b_xflags & BX_BKGRDINPROG) 1650 panic("losing buffer 3"); 1651 LIST_REMOVE(bp, b_hash); 1652 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1653 1654 if (bp->b_bufsize) 1655 allocbuf(bp, 0); 1656 1657 bp->b_flags = 0; 1658 bp->b_xflags = 0; 1659 bp->b_dev = NODEV; 1660 bp->b_vp = NULL; 1661 bp->b_blkno = bp->b_lblkno = 0; 1662 bp->b_offset = NOOFFSET; 1663 bp->b_iodone = 0; 1664 bp->b_error = 0; 1665 bp->b_resid = 0; 1666 bp->b_bcount = 0; 1667 bp->b_npages = 0; 1668 bp->b_dirtyoff = bp->b_dirtyend = 0; 1669 1670 LIST_INIT(&bp->b_dep); 1671 1672 /* 1673 * If we are defragging then free the buffer. 1674 */ 1675 if (defrag) { 1676 bp->b_flags |= B_INVAL; 1677 bfreekva(bp); 1678 brelse(bp); 1679 defrag = 0; 1680 goto restart; 1681 } 1682 1683 /* 1684 * If we are overcomitted then recover the buffer and its 1685 * KVM space. This occurs in rare situations when multiple 1686 * processes are blocked in getnewbuf() or allocbuf(). 1687 */ 1688 if (bufspace >= hibufspace) 1689 flushingbufs = 1; 1690 if (flushingbufs && bp->b_kvasize != 0) { 1691 bp->b_flags |= B_INVAL; 1692 bfreekva(bp); 1693 brelse(bp); 1694 goto restart; 1695 } 1696 if (bufspace < lobufspace) 1697 flushingbufs = 0; 1698 break; 1699 } 1700 1701 /* 1702 * If we exhausted our list, sleep as appropriate. We may have to 1703 * wakeup various daemons and write out some dirty buffers. 1704 * 1705 * Generally we are sleeping due to insufficient buffer space. 1706 */ 1707 1708 if (bp == NULL) { 1709 int flags; 1710 char *waitmsg; 1711 1712 if (defrag) { 1713 flags = VFS_BIO_NEED_BUFSPACE; 1714 waitmsg = "nbufkv"; 1715 } else if (bufspace >= hibufspace) { 1716 waitmsg = "nbufbs"; 1717 flags = VFS_BIO_NEED_BUFSPACE; 1718 } else { 1719 waitmsg = "newbuf"; 1720 flags = VFS_BIO_NEED_ANY; 1721 } 1722 1723 bd_speedup(); /* heeeelp */ 1724 1725 needsbuffer |= flags; 1726 while (needsbuffer & flags) { 1727 if (tsleep(&needsbuffer, (PRIBIO + 4) | slpflag, 1728 waitmsg, slptimeo)) 1729 return (NULL); 1730 } 1731 } else { 1732 /* 1733 * We finally have a valid bp. We aren't quite out of the 1734 * woods, we still have to reserve kva space. In order 1735 * to keep fragmentation sane we only allocate kva in 1736 * BKVASIZE chunks. 1737 */ 1738 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 1739 1740 if (maxsize != bp->b_kvasize) { 1741 vm_offset_t addr = 0; 1742 1743 bfreekva(bp); 1744 1745 vm_map_lock(buffer_map); 1746 1747 if (vm_map_findspace(buffer_map, 1748 vm_map_min(buffer_map), maxsize, &addr)) { 1749 /* 1750 * Uh oh. Buffer map is to fragmented. We 1751 * must defragment the map. 1752 */ 1753 vm_map_unlock(buffer_map); 1754 ++bufdefragcnt; 1755 defrag = 1; 1756 bp->b_flags |= B_INVAL; 1757 brelse(bp); 1758 goto restart; 1759 } 1760 if (addr) { 1761 vm_map_insert(buffer_map, NULL, 0, 1762 addr, addr + maxsize, 1763 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT); 1764 1765 bp->b_kvabase = (caddr_t) addr; 1766 bp->b_kvasize = maxsize; 1767 bufspace += bp->b_kvasize; 1768 ++bufreusecnt; 1769 } 1770 vm_map_unlock(buffer_map); 1771 } 1772 bp->b_data = bp->b_kvabase; 1773 } 1774 return(bp); 1775 } 1776 1777 /* 1778 * buf_daemon: 1779 * 1780 * buffer flushing daemon. Buffers are normally flushed by the 1781 * update daemon but if it cannot keep up this process starts to 1782 * take the load in an attempt to prevent getnewbuf() from blocking. 1783 */ 1784 1785 static struct proc *bufdaemonproc; 1786 1787 static struct kproc_desc buf_kp = { 1788 "bufdaemon", 1789 buf_daemon, 1790 &bufdaemonproc 1791 }; 1792 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp) 1793 1794 static void 1795 buf_daemon() 1796 { 1797 int s; 1798 1799 /* 1800 * This process needs to be suspended prior to shutdown sync. 1801 */ 1802 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc, bufdaemonproc, 1803 SHUTDOWN_PRI_LAST); 1804 1805 /* 1806 * This process is allowed to take the buffer cache to the limit 1807 */ 1808 s = splbio(); 1809 1810 for (;;) { 1811 kproc_suspend_loop(bufdaemonproc); 1812 1813 /* 1814 * Do the flush. Limit the amount of in-transit I/O we 1815 * allow to build up, otherwise we would completely saturate 1816 * the I/O system. Wakeup any waiting processes before we 1817 * normally would so they can run in parallel with our drain. 1818 */ 1819 while (numdirtybuffers > lodirtybuffers) { 1820 if (flushbufqueues() == 0) 1821 break; 1822 waitrunningbufspace(); 1823 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 1824 } 1825 1826 /* 1827 * Only clear bd_request if we have reached our low water 1828 * mark. The buf_daemon normally waits 5 seconds and 1829 * then incrementally flushes any dirty buffers that have 1830 * built up, within reason. 1831 * 1832 * If we were unable to hit our low water mark and couldn't 1833 * find any flushable buffers, we sleep half a second. 1834 * Otherwise we loop immediately. 1835 */ 1836 if (numdirtybuffers <= lodirtybuffers) { 1837 /* 1838 * We reached our low water mark, reset the 1839 * request and sleep until we are needed again. 1840 * The sleep is just so the suspend code works. 1841 */ 1842 bd_request = 0; 1843 tsleep(&bd_request, PVM, "psleep", hz); 1844 } else { 1845 /* 1846 * We couldn't find any flushable dirty buffers but 1847 * still have too many dirty buffers, we 1848 * have to sleep and try again. (rare) 1849 */ 1850 tsleep(&bd_request, PVM, "qsleep", hz / 2); 1851 } 1852 } 1853 } 1854 1855 /* 1856 * flushbufqueues: 1857 * 1858 * Try to flush a buffer in the dirty queue. We must be careful to 1859 * free up B_INVAL buffers instead of write them, which NFS is 1860 * particularly sensitive to. 1861 */ 1862 1863 static int 1864 flushbufqueues(void) 1865 { 1866 struct buf *bp; 1867 int r = 0; 1868 1869 bp = TAILQ_FIRST(&bufqueues[QUEUE_DIRTY]); 1870 1871 while (bp) { 1872 KASSERT((bp->b_flags & B_DELWRI), ("unexpected clean buffer %p", bp)); 1873 if ((bp->b_flags & B_DELWRI) != 0 && 1874 (bp->b_xflags & BX_BKGRDINPROG) == 0) { 1875 if (bp->b_flags & B_INVAL) { 1876 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) 1877 panic("flushbufqueues: locked buf"); 1878 bremfree(bp); 1879 brelse(bp); 1880 ++r; 1881 break; 1882 } 1883 if (LIST_FIRST(&bp->b_dep) != NULL && 1884 bioops.io_countdeps && 1885 (bp->b_flags & B_DEFERRED) == 0 && 1886 (*bioops.io_countdeps)(bp, 0)) { 1887 TAILQ_REMOVE(&bufqueues[QUEUE_DIRTY], 1888 bp, b_freelist); 1889 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], 1890 bp, b_freelist); 1891 bp->b_flags |= B_DEFERRED; 1892 bp = TAILQ_FIRST(&bufqueues[QUEUE_DIRTY]); 1893 continue; 1894 } 1895 vfs_bio_awrite(bp); 1896 ++r; 1897 break; 1898 } 1899 bp = TAILQ_NEXT(bp, b_freelist); 1900 } 1901 return (r); 1902 } 1903 1904 /* 1905 * Check to see if a block is currently memory resident. 1906 */ 1907 struct buf * 1908 incore(struct vnode * vp, daddr_t blkno) 1909 { 1910 struct buf *bp; 1911 1912 int s = splbio(); 1913 bp = gbincore(vp, blkno); 1914 splx(s); 1915 return (bp); 1916 } 1917 1918 /* 1919 * Returns true if no I/O is needed to access the 1920 * associated VM object. This is like incore except 1921 * it also hunts around in the VM system for the data. 1922 */ 1923 1924 int 1925 inmem(struct vnode * vp, daddr_t blkno) 1926 { 1927 vm_object_t obj; 1928 vm_offset_t toff, tinc, size; 1929 vm_page_t m; 1930 vm_ooffset_t off; 1931 1932 if (incore(vp, blkno)) 1933 return 1; 1934 if (vp->v_mount == NULL) 1935 return 0; 1936 if (VOP_GETVOBJECT(vp, &obj) != 0 || (vp->v_flag & VOBJBUF) == 0) 1937 return 0; 1938 1939 size = PAGE_SIZE; 1940 if (size > vp->v_mount->mnt_stat.f_iosize) 1941 size = vp->v_mount->mnt_stat.f_iosize; 1942 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 1943 1944 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 1945 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 1946 if (!m) 1947 return 0; 1948 tinc = size; 1949 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 1950 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 1951 if (vm_page_is_valid(m, 1952 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 1953 return 0; 1954 } 1955 return 1; 1956 } 1957 1958 /* 1959 * vfs_setdirty: 1960 * 1961 * Sets the dirty range for a buffer based on the status of the dirty 1962 * bits in the pages comprising the buffer. 1963 * 1964 * The range is limited to the size of the buffer. 1965 * 1966 * This routine is primarily used by NFS, but is generalized for the 1967 * B_VMIO case. 1968 */ 1969 static void 1970 vfs_setdirty(struct buf *bp) 1971 { 1972 int i; 1973 vm_object_t object; 1974 1975 /* 1976 * Degenerate case - empty buffer 1977 */ 1978 1979 if (bp->b_bufsize == 0) 1980 return; 1981 1982 /* 1983 * We qualify the scan for modified pages on whether the 1984 * object has been flushed yet. The OBJ_WRITEABLE flag 1985 * is not cleared simply by protecting pages off. 1986 */ 1987 1988 if ((bp->b_flags & B_VMIO) == 0) 1989 return; 1990 1991 object = bp->b_pages[0]->object; 1992 1993 if ((object->flags & OBJ_WRITEABLE) && !(object->flags & OBJ_MIGHTBEDIRTY)) 1994 printf("Warning: object %p writeable but not mightbedirty\n", object); 1995 if (!(object->flags & OBJ_WRITEABLE) && (object->flags & OBJ_MIGHTBEDIRTY)) 1996 printf("Warning: object %p mightbedirty but not writeable\n", object); 1997 1998 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) { 1999 vm_offset_t boffset; 2000 vm_offset_t eoffset; 2001 2002 /* 2003 * test the pages to see if they have been modified directly 2004 * by users through the VM system. 2005 */ 2006 for (i = 0; i < bp->b_npages; i++) { 2007 vm_page_flag_clear(bp->b_pages[i], PG_ZERO); 2008 vm_page_test_dirty(bp->b_pages[i]); 2009 } 2010 2011 /* 2012 * Calculate the encompassing dirty range, boffset and eoffset, 2013 * (eoffset - boffset) bytes. 2014 */ 2015 2016 for (i = 0; i < bp->b_npages; i++) { 2017 if (bp->b_pages[i]->dirty) 2018 break; 2019 } 2020 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2021 2022 for (i = bp->b_npages - 1; i >= 0; --i) { 2023 if (bp->b_pages[i]->dirty) { 2024 break; 2025 } 2026 } 2027 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2028 2029 /* 2030 * Fit it to the buffer. 2031 */ 2032 2033 if (eoffset > bp->b_bcount) 2034 eoffset = bp->b_bcount; 2035 2036 /* 2037 * If we have a good dirty range, merge with the existing 2038 * dirty range. 2039 */ 2040 2041 if (boffset < eoffset) { 2042 if (bp->b_dirtyoff > boffset) 2043 bp->b_dirtyoff = boffset; 2044 if (bp->b_dirtyend < eoffset) 2045 bp->b_dirtyend = eoffset; 2046 } 2047 } 2048 } 2049 2050 /* 2051 * getblk: 2052 * 2053 * Get a block given a specified block and offset into a file/device. 2054 * The buffers B_DONE bit will be cleared on return, making it almost 2055 * ready for an I/O initiation. B_INVAL may or may not be set on 2056 * return. The caller should clear B_INVAL prior to initiating a 2057 * READ. 2058 * 2059 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2060 * an existing buffer. 2061 * 2062 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2063 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2064 * and then cleared based on the backing VM. If the previous buffer is 2065 * non-0-sized but invalid, B_CACHE will be cleared. 2066 * 2067 * If getblk() must create a new buffer, the new buffer is returned with 2068 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2069 * case it is returned with B_INVAL clear and B_CACHE set based on the 2070 * backing VM. 2071 * 2072 * getblk() also forces a VOP_BWRITE() for any B_DELWRI buffer whos 2073 * B_CACHE bit is clear. 2074 * 2075 * What this means, basically, is that the caller should use B_CACHE to 2076 * determine whether the buffer is fully valid or not and should clear 2077 * B_INVAL prior to issuing a read. If the caller intends to validate 2078 * the buffer by loading its data area with something, the caller needs 2079 * to clear B_INVAL. If the caller does this without issuing an I/O, 2080 * the caller should set B_CACHE ( as an optimization ), else the caller 2081 * should issue the I/O and biodone() will set B_CACHE if the I/O was 2082 * a write attempt or if it was a successfull read. If the caller 2083 * intends to issue a READ, the caller must clear B_INVAL and B_ERROR 2084 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 2085 */ 2086 struct buf * 2087 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo) 2088 { 2089 struct buf *bp; 2090 int s; 2091 struct bufhashhdr *bh; 2092 2093 if (size > MAXBSIZE) 2094 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 2095 2096 s = splbio(); 2097 loop: 2098 /* 2099 * Block if we are low on buffers. Certain processes are allowed 2100 * to completely exhaust the buffer cache. 2101 * 2102 * If this check ever becomes a bottleneck it may be better to 2103 * move it into the else, when gbincore() fails. At the moment 2104 * it isn't a problem. 2105 * 2106 * XXX remove, we cannot afford to block anywhere if holding a vnode 2107 * lock in low-memory situation, so take it to the max. 2108 */ 2109 if (numfreebuffers == 0) { 2110 if (!curproc) 2111 return NULL; 2112 needsbuffer |= VFS_BIO_NEED_ANY; 2113 tsleep(&needsbuffer, (PRIBIO + 4) | slpflag, "newbuf", 2114 slptimeo); 2115 } 2116 2117 if ((bp = gbincore(vp, blkno))) { 2118 /* 2119 * Buffer is in-core. If the buffer is not busy, it must 2120 * be on a queue. 2121 */ 2122 2123 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) { 2124 if (BUF_TIMELOCK(bp, LK_EXCLUSIVE | LK_SLEEPFAIL, 2125 "getblk", slpflag, slptimeo) == ENOLCK) 2126 goto loop; 2127 splx(s); 2128 return (struct buf *) NULL; 2129 } 2130 2131 /* 2132 * The buffer is locked. B_CACHE is cleared if the buffer is 2133 * invalid. Ohterwise, for a non-VMIO buffer, B_CACHE is set 2134 * and for a VMIO buffer B_CACHE is adjusted according to the 2135 * backing VM cache. 2136 */ 2137 if (bp->b_flags & B_INVAL) 2138 bp->b_flags &= ~B_CACHE; 2139 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 2140 bp->b_flags |= B_CACHE; 2141 bremfree(bp); 2142 2143 /* 2144 * check for size inconsistancies for non-VMIO case. 2145 */ 2146 2147 if (bp->b_bcount != size) { 2148 if ((bp->b_flags & B_VMIO) == 0 || 2149 (size > bp->b_kvasize)) { 2150 if (bp->b_flags & B_DELWRI) { 2151 bp->b_flags |= B_NOCACHE; 2152 VOP_BWRITE(bp->b_vp, bp); 2153 } else { 2154 if ((bp->b_flags & B_VMIO) && 2155 (LIST_FIRST(&bp->b_dep) == NULL)) { 2156 bp->b_flags |= B_RELBUF; 2157 brelse(bp); 2158 } else { 2159 bp->b_flags |= B_NOCACHE; 2160 VOP_BWRITE(bp->b_vp, bp); 2161 } 2162 } 2163 goto loop; 2164 } 2165 } 2166 2167 /* 2168 * If the size is inconsistant in the VMIO case, we can resize 2169 * the buffer. This might lead to B_CACHE getting set or 2170 * cleared. If the size has not changed, B_CACHE remains 2171 * unchanged from its previous state. 2172 */ 2173 2174 if (bp->b_bcount != size) 2175 allocbuf(bp, size); 2176 2177 KASSERT(bp->b_offset != NOOFFSET, 2178 ("getblk: no buffer offset")); 2179 2180 /* 2181 * A buffer with B_DELWRI set and B_CACHE clear must 2182 * be committed before we can return the buffer in 2183 * order to prevent the caller from issuing a read 2184 * ( due to B_CACHE not being set ) and overwriting 2185 * it. 2186 * 2187 * Most callers, including NFS and FFS, need this to 2188 * operate properly either because they assume they 2189 * can issue a read if B_CACHE is not set, or because 2190 * ( for example ) an uncached B_DELWRI might loop due 2191 * to softupdates re-dirtying the buffer. In the latter 2192 * case, B_CACHE is set after the first write completes, 2193 * preventing further loops. 2194 * 2195 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 2196 * above while extending the buffer, we cannot allow the 2197 * buffer to remain with B_CACHE set after the write 2198 * completes or it will represent a corrupt state. To 2199 * deal with this we set B_NOCACHE to scrap the buffer 2200 * after the write. 2201 * 2202 * We might be able to do something fancy, like setting 2203 * B_CACHE in bwrite() except if B_DELWRI is already set, 2204 * so the below call doesn't set B_CACHE, but that gets real 2205 * confusing. This is much easier. 2206 */ 2207 2208 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 2209 bp->b_flags |= B_NOCACHE; 2210 VOP_BWRITE(bp->b_vp, bp); 2211 goto loop; 2212 } 2213 2214 splx(s); 2215 bp->b_flags &= ~B_DONE; 2216 } else { 2217 /* 2218 * Buffer is not in-core, create new buffer. The buffer 2219 * returned by getnewbuf() is locked. Note that the returned 2220 * buffer is also considered valid (not marked B_INVAL). 2221 */ 2222 int bsize, maxsize, vmio; 2223 off_t offset; 2224 2225 if (vn_isdisk(vp, NULL)) 2226 bsize = DEV_BSIZE; 2227 else if (vp->v_mountedhere) 2228 bsize = vp->v_mountedhere->mnt_stat.f_iosize; 2229 else if (vp->v_mount) 2230 bsize = vp->v_mount->mnt_stat.f_iosize; 2231 else 2232 bsize = size; 2233 2234 offset = (off_t)blkno * bsize; 2235 vmio = (VOP_GETVOBJECT(vp, NULL) == 0) && (vp->v_flag & VOBJBUF); 2236 maxsize = vmio ? size + (offset & PAGE_MASK) : size; 2237 maxsize = imax(maxsize, bsize); 2238 2239 if ((bp = getnewbuf(slpflag, slptimeo, size, maxsize)) == NULL) { 2240 if (slpflag || slptimeo) { 2241 splx(s); 2242 return NULL; 2243 } 2244 goto loop; 2245 } 2246 2247 /* 2248 * This code is used to make sure that a buffer is not 2249 * created while the getnewbuf routine is blocked. 2250 * This can be a problem whether the vnode is locked or not. 2251 * If the buffer is created out from under us, we have to 2252 * throw away the one we just created. There is now window 2253 * race because we are safely running at splbio() from the 2254 * point of the duplicate buffer creation through to here, 2255 * and we've locked the buffer. 2256 */ 2257 if (gbincore(vp, blkno)) { 2258 bp->b_flags |= B_INVAL; 2259 brelse(bp); 2260 goto loop; 2261 } 2262 2263 /* 2264 * Insert the buffer into the hash, so that it can 2265 * be found by incore. 2266 */ 2267 bp->b_blkno = bp->b_lblkno = blkno; 2268 bp->b_offset = offset; 2269 2270 bgetvp(vp, bp); 2271 LIST_REMOVE(bp, b_hash); 2272 bh = bufhash(vp, blkno); 2273 LIST_INSERT_HEAD(bh, bp, b_hash); 2274 2275 /* 2276 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 2277 * buffer size starts out as 0, B_CACHE will be set by 2278 * allocbuf() for the VMIO case prior to it testing the 2279 * backing store for validity. 2280 */ 2281 2282 if (vmio) { 2283 bp->b_flags |= B_VMIO; 2284 #if defined(VFS_BIO_DEBUG) 2285 if (vp->v_type != VREG && vp->v_type != VBLK) 2286 printf("getblk: vmioing file type %d???\n", vp->v_type); 2287 #endif 2288 } else { 2289 bp->b_flags &= ~B_VMIO; 2290 } 2291 2292 allocbuf(bp, size); 2293 2294 splx(s); 2295 bp->b_flags &= ~B_DONE; 2296 } 2297 return (bp); 2298 } 2299 2300 /* 2301 * Get an empty, disassociated buffer of given size. The buffer is initially 2302 * set to B_INVAL. 2303 */ 2304 struct buf * 2305 geteblk(int size) 2306 { 2307 struct buf *bp; 2308 int s; 2309 int maxsize; 2310 2311 maxsize = (size + BKVAMASK) & ~BKVAMASK; 2312 2313 s = splbio(); 2314 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0); 2315 splx(s); 2316 allocbuf(bp, size); 2317 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 2318 return (bp); 2319 } 2320 2321 2322 /* 2323 * This code constitutes the buffer memory from either anonymous system 2324 * memory (in the case of non-VMIO operations) or from an associated 2325 * VM object (in the case of VMIO operations). This code is able to 2326 * resize a buffer up or down. 2327 * 2328 * Note that this code is tricky, and has many complications to resolve 2329 * deadlock or inconsistant data situations. Tread lightly!!! 2330 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 2331 * the caller. Calling this code willy nilly can result in the loss of data. 2332 * 2333 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 2334 * B_CACHE for the non-VMIO case. 2335 */ 2336 2337 int 2338 allocbuf(struct buf *bp, int size) 2339 { 2340 int newbsize, mbsize; 2341 int i; 2342 2343 if (BUF_REFCNT(bp) == 0) 2344 panic("allocbuf: buffer not busy"); 2345 2346 if (bp->b_kvasize < size) 2347 panic("allocbuf: buffer too small"); 2348 2349 if ((bp->b_flags & B_VMIO) == 0) { 2350 caddr_t origbuf; 2351 int origbufsize; 2352 /* 2353 * Just get anonymous memory from the kernel. Don't 2354 * mess with B_CACHE. 2355 */ 2356 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2357 #if !defined(NO_B_MALLOC) 2358 if (bp->b_flags & B_MALLOC) 2359 newbsize = mbsize; 2360 else 2361 #endif 2362 newbsize = round_page(size); 2363 2364 if (newbsize < bp->b_bufsize) { 2365 #if !defined(NO_B_MALLOC) 2366 /* 2367 * malloced buffers are not shrunk 2368 */ 2369 if (bp->b_flags & B_MALLOC) { 2370 if (newbsize) { 2371 bp->b_bcount = size; 2372 } else { 2373 free(bp->b_data, M_BIOBUF); 2374 if (bp->b_bufsize) { 2375 bufmallocspace -= bp->b_bufsize; 2376 bufspacewakeup(); 2377 bp->b_bufsize = 0; 2378 } 2379 bp->b_data = bp->b_kvabase; 2380 bp->b_bcount = 0; 2381 bp->b_flags &= ~B_MALLOC; 2382 } 2383 return 1; 2384 } 2385 #endif 2386 vm_hold_free_pages( 2387 bp, 2388 (vm_offset_t) bp->b_data + newbsize, 2389 (vm_offset_t) bp->b_data + bp->b_bufsize); 2390 } else if (newbsize > bp->b_bufsize) { 2391 #if !defined(NO_B_MALLOC) 2392 /* 2393 * We only use malloced memory on the first allocation. 2394 * and revert to page-allocated memory when the buffer 2395 * grows. 2396 */ 2397 if ( (bufmallocspace < maxbufmallocspace) && 2398 (bp->b_bufsize == 0) && 2399 (mbsize <= PAGE_SIZE/2)) { 2400 2401 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 2402 bp->b_bufsize = mbsize; 2403 bp->b_bcount = size; 2404 bp->b_flags |= B_MALLOC; 2405 bufmallocspace += mbsize; 2406 return 1; 2407 } 2408 #endif 2409 origbuf = NULL; 2410 origbufsize = 0; 2411 #if !defined(NO_B_MALLOC) 2412 /* 2413 * If the buffer is growing on its other-than-first allocation, 2414 * then we revert to the page-allocation scheme. 2415 */ 2416 if (bp->b_flags & B_MALLOC) { 2417 origbuf = bp->b_data; 2418 origbufsize = bp->b_bufsize; 2419 bp->b_data = bp->b_kvabase; 2420 if (bp->b_bufsize) { 2421 bufmallocspace -= bp->b_bufsize; 2422 bufspacewakeup(); 2423 bp->b_bufsize = 0; 2424 } 2425 bp->b_flags &= ~B_MALLOC; 2426 newbsize = round_page(newbsize); 2427 } 2428 #endif 2429 vm_hold_load_pages( 2430 bp, 2431 (vm_offset_t) bp->b_data + bp->b_bufsize, 2432 (vm_offset_t) bp->b_data + newbsize); 2433 #if !defined(NO_B_MALLOC) 2434 if (origbuf) { 2435 bcopy(origbuf, bp->b_data, origbufsize); 2436 free(origbuf, M_BIOBUF); 2437 } 2438 #endif 2439 } 2440 } else { 2441 vm_page_t m; 2442 int desiredpages; 2443 2444 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2445 desiredpages = (size == 0) ? 0 : 2446 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 2447 2448 #if !defined(NO_B_MALLOC) 2449 if (bp->b_flags & B_MALLOC) 2450 panic("allocbuf: VMIO buffer can't be malloced"); 2451 #endif 2452 /* 2453 * Set B_CACHE initially if buffer is 0 length or will become 2454 * 0-length. 2455 */ 2456 if (size == 0 || bp->b_bufsize == 0) 2457 bp->b_flags |= B_CACHE; 2458 2459 if (newbsize < bp->b_bufsize) { 2460 /* 2461 * DEV_BSIZE aligned new buffer size is less then the 2462 * DEV_BSIZE aligned existing buffer size. Figure out 2463 * if we have to remove any pages. 2464 */ 2465 if (desiredpages < bp->b_npages) { 2466 for (i = desiredpages; i < bp->b_npages; i++) { 2467 /* 2468 * the page is not freed here -- it 2469 * is the responsibility of 2470 * vnode_pager_setsize 2471 */ 2472 m = bp->b_pages[i]; 2473 KASSERT(m != bogus_page, 2474 ("allocbuf: bogus page found")); 2475 while (vm_page_sleep_busy(m, TRUE, "biodep")) 2476 ; 2477 2478 bp->b_pages[i] = NULL; 2479 vm_page_unwire(m, 0); 2480 } 2481 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) + 2482 (desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages)); 2483 bp->b_npages = desiredpages; 2484 } 2485 } else if (size > bp->b_bcount) { 2486 /* 2487 * We are growing the buffer, possibly in a 2488 * byte-granular fashion. 2489 */ 2490 struct vnode *vp; 2491 vm_object_t obj; 2492 vm_offset_t toff; 2493 vm_offset_t tinc; 2494 2495 /* 2496 * Step 1, bring in the VM pages from the object, 2497 * allocating them if necessary. We must clear 2498 * B_CACHE if these pages are not valid for the 2499 * range covered by the buffer. 2500 */ 2501 2502 vp = bp->b_vp; 2503 VOP_GETVOBJECT(vp, &obj); 2504 2505 while (bp->b_npages < desiredpages) { 2506 vm_page_t m; 2507 vm_pindex_t pi; 2508 2509 pi = OFF_TO_IDX(bp->b_offset) + bp->b_npages; 2510 if ((m = vm_page_lookup(obj, pi)) == NULL) { 2511 /* 2512 * note: must allocate system pages 2513 * since blocking here could intefere 2514 * with paging I/O, no matter which 2515 * process we are. 2516 */ 2517 m = vm_page_alloc(obj, pi, VM_ALLOC_SYSTEM); 2518 if (m == NULL) { 2519 VM_WAIT; 2520 vm_pageout_deficit += desiredpages - bp->b_npages; 2521 } else { 2522 vm_page_wire(m); 2523 vm_page_wakeup(m); 2524 bp->b_flags &= ~B_CACHE; 2525 bp->b_pages[bp->b_npages] = m; 2526 ++bp->b_npages; 2527 } 2528 continue; 2529 } 2530 2531 /* 2532 * We found a page. If we have to sleep on it, 2533 * retry because it might have gotten freed out 2534 * from under us. 2535 * 2536 * We can only test PG_BUSY here. Blocking on 2537 * m->busy might lead to a deadlock: 2538 * 2539 * vm_fault->getpages->cluster_read->allocbuf 2540 * 2541 */ 2542 2543 if (vm_page_sleep_busy(m, FALSE, "pgtblk")) 2544 continue; 2545 2546 /* 2547 * We have a good page. Should we wakeup the 2548 * page daemon? 2549 */ 2550 if ((curproc != pageproc) && 2551 ((m->queue - m->pc) == PQ_CACHE) && 2552 ((cnt.v_free_count + cnt.v_cache_count) < 2553 (cnt.v_free_min + cnt.v_cache_min))) { 2554 pagedaemon_wakeup(); 2555 } 2556 vm_page_flag_clear(m, PG_ZERO); 2557 vm_page_wire(m); 2558 bp->b_pages[bp->b_npages] = m; 2559 ++bp->b_npages; 2560 } 2561 2562 /* 2563 * Step 2. We've loaded the pages into the buffer, 2564 * we have to figure out if we can still have B_CACHE 2565 * set. Note that B_CACHE is set according to the 2566 * byte-granular range ( bcount and size ), new the 2567 * aligned range ( newbsize ). 2568 * 2569 * The VM test is against m->valid, which is DEV_BSIZE 2570 * aligned. Needless to say, the validity of the data 2571 * needs to also be DEV_BSIZE aligned. Note that this 2572 * fails with NFS if the server or some other client 2573 * extends the file's EOF. If our buffer is resized, 2574 * B_CACHE may remain set! XXX 2575 */ 2576 2577 toff = bp->b_bcount; 2578 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 2579 2580 while ((bp->b_flags & B_CACHE) && toff < size) { 2581 vm_pindex_t pi; 2582 2583 if (tinc > (size - toff)) 2584 tinc = size - toff; 2585 2586 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 2587 PAGE_SHIFT; 2588 2589 vfs_buf_test_cache( 2590 bp, 2591 bp->b_offset, 2592 toff, 2593 tinc, 2594 bp->b_pages[pi] 2595 ); 2596 toff += tinc; 2597 tinc = PAGE_SIZE; 2598 } 2599 2600 /* 2601 * Step 3, fixup the KVM pmap. Remember that 2602 * bp->b_data is relative to bp->b_offset, but 2603 * bp->b_offset may be offset into the first page. 2604 */ 2605 2606 bp->b_data = (caddr_t) 2607 trunc_page((vm_offset_t)bp->b_data); 2608 pmap_qenter( 2609 (vm_offset_t)bp->b_data, 2610 bp->b_pages, 2611 bp->b_npages 2612 ); 2613 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 2614 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 2615 } 2616 } 2617 if (newbsize < bp->b_bufsize) 2618 bufspacewakeup(); 2619 bp->b_bufsize = newbsize; /* actual buffer allocation */ 2620 bp->b_bcount = size; /* requested buffer size */ 2621 return 1; 2622 } 2623 2624 /* 2625 * biowait: 2626 * 2627 * Wait for buffer I/O completion, returning error status. The buffer 2628 * is left locked and B_DONE on return. B_EINTR is converted into a EINTR 2629 * error and cleared. 2630 */ 2631 int 2632 biowait(register struct buf * bp) 2633 { 2634 int s; 2635 2636 s = splbio(); 2637 while ((bp->b_flags & B_DONE) == 0) { 2638 #if defined(NO_SCHEDULE_MODS) 2639 tsleep(bp, PRIBIO, "biowait", 0); 2640 #else 2641 if (bp->b_flags & B_READ) 2642 tsleep(bp, PRIBIO, "biord", 0); 2643 else 2644 tsleep(bp, PRIBIO, "biowr", 0); 2645 #endif 2646 } 2647 splx(s); 2648 if (bp->b_flags & B_EINTR) { 2649 bp->b_flags &= ~B_EINTR; 2650 return (EINTR); 2651 } 2652 if (bp->b_flags & B_ERROR) { 2653 return (bp->b_error ? bp->b_error : EIO); 2654 } else { 2655 return (0); 2656 } 2657 } 2658 2659 /* 2660 * biodone: 2661 * 2662 * Finish I/O on a buffer, optionally calling a completion function. 2663 * This is usually called from an interrupt so process blocking is 2664 * not allowed. 2665 * 2666 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 2667 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 2668 * assuming B_INVAL is clear. 2669 * 2670 * For the VMIO case, we set B_CACHE if the op was a read and no 2671 * read error occured, or if the op was a write. B_CACHE is never 2672 * set if the buffer is invalid or otherwise uncacheable. 2673 * 2674 * biodone does not mess with B_INVAL, allowing the I/O routine or the 2675 * initiator to leave B_INVAL set to brelse the buffer out of existance 2676 * in the biodone routine. 2677 */ 2678 void 2679 biodone(register struct buf * bp) 2680 { 2681 int s, error; 2682 2683 s = splbio(); 2684 2685 KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp, BUF_REFCNT(bp))); 2686 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 2687 2688 bp->b_flags |= B_DONE; 2689 runningbufwakeup(bp); 2690 2691 if (bp->b_flags & B_FREEBUF) { 2692 brelse(bp); 2693 splx(s); 2694 return; 2695 } 2696 2697 if ((bp->b_flags & B_READ) == 0) { 2698 vwakeup(bp); 2699 } 2700 2701 /* call optional completion function if requested */ 2702 if (bp->b_flags & B_CALL) { 2703 bp->b_flags &= ~B_CALL; 2704 (*bp->b_iodone) (bp); 2705 splx(s); 2706 return; 2707 } 2708 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_complete) 2709 (*bioops.io_complete)(bp); 2710 2711 if (bp->b_flags & B_VMIO) { 2712 int i; 2713 vm_ooffset_t foff; 2714 vm_page_t m; 2715 vm_object_t obj; 2716 int iosize; 2717 struct vnode *vp = bp->b_vp; 2718 2719 error = VOP_GETVOBJECT(vp, &obj); 2720 2721 #if defined(VFS_BIO_DEBUG) 2722 if (vp->v_usecount == 0) { 2723 panic("biodone: zero vnode ref count"); 2724 } 2725 2726 if (error) { 2727 panic("biodone: missing VM object"); 2728 } 2729 2730 if ((vp->v_flag & VOBJBUF) == 0) { 2731 panic("biodone: vnode is not setup for merged cache"); 2732 } 2733 #endif 2734 2735 foff = bp->b_offset; 2736 KASSERT(bp->b_offset != NOOFFSET, 2737 ("biodone: no buffer offset")); 2738 2739 if (error) { 2740 panic("biodone: no object"); 2741 } 2742 #if defined(VFS_BIO_DEBUG) 2743 if (obj->paging_in_progress < bp->b_npages) { 2744 printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n", 2745 obj->paging_in_progress, bp->b_npages); 2746 } 2747 #endif 2748 2749 /* 2750 * Set B_CACHE if the op was a normal read and no error 2751 * occured. B_CACHE is set for writes in the b*write() 2752 * routines. 2753 */ 2754 iosize = bp->b_bcount - bp->b_resid; 2755 if ((bp->b_flags & (B_READ|B_FREEBUF|B_INVAL|B_NOCACHE|B_ERROR)) == B_READ) { 2756 bp->b_flags |= B_CACHE; 2757 } 2758 2759 for (i = 0; i < bp->b_npages; i++) { 2760 int bogusflag = 0; 2761 int resid; 2762 2763 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 2764 if (resid > iosize) 2765 resid = iosize; 2766 2767 /* 2768 * cleanup bogus pages, restoring the originals 2769 */ 2770 m = bp->b_pages[i]; 2771 if (m == bogus_page) { 2772 bogusflag = 1; 2773 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 2774 if (m == NULL) 2775 panic("biodone: page disappeared"); 2776 bp->b_pages[i] = m; 2777 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 2778 } 2779 #if defined(VFS_BIO_DEBUG) 2780 if (OFF_TO_IDX(foff) != m->pindex) { 2781 printf( 2782 "biodone: foff(%lu)/m->pindex(%d) mismatch\n", 2783 (unsigned long)foff, m->pindex); 2784 } 2785 #endif 2786 2787 /* 2788 * In the write case, the valid and clean bits are 2789 * already changed correctly ( see bdwrite() ), so we 2790 * only need to do this here in the read case. 2791 */ 2792 if ((bp->b_flags & B_READ) && !bogusflag && resid > 0) { 2793 vfs_page_set_valid(bp, foff, i, m); 2794 } 2795 vm_page_flag_clear(m, PG_ZERO); 2796 2797 /* 2798 * when debugging new filesystems or buffer I/O methods, this 2799 * is the most common error that pops up. if you see this, you 2800 * have not set the page busy flag correctly!!! 2801 */ 2802 if (m->busy == 0) { 2803 printf("biodone: page busy < 0, " 2804 "pindex: %d, foff: 0x(%x,%x), " 2805 "resid: %d, index: %d\n", 2806 (int) m->pindex, (int)(foff >> 32), 2807 (int) foff & 0xffffffff, resid, i); 2808 if (!vn_isdisk(vp, NULL)) 2809 printf(" iosize: %ld, lblkno: %d, flags: 0x%lx, npages: %d\n", 2810 bp->b_vp->v_mount->mnt_stat.f_iosize, 2811 (int) bp->b_lblkno, 2812 bp->b_flags, bp->b_npages); 2813 else 2814 printf(" VDEV, lblkno: %d, flags: 0x%lx, npages: %d\n", 2815 (int) bp->b_lblkno, 2816 bp->b_flags, bp->b_npages); 2817 printf(" valid: 0x%x, dirty: 0x%x, wired: %d\n", 2818 m->valid, m->dirty, m->wire_count); 2819 panic("biodone: page busy < 0\n"); 2820 } 2821 vm_page_io_finish(m); 2822 vm_object_pip_subtract(obj, 1); 2823 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2824 iosize -= resid; 2825 } 2826 if (obj) 2827 vm_object_pip_wakeupn(obj, 0); 2828 } 2829 2830 /* 2831 * For asynchronous completions, release the buffer now. The brelse 2832 * will do a wakeup there if necessary - so no need to do a wakeup 2833 * here in the async case. The sync case always needs to do a wakeup. 2834 */ 2835 2836 if (bp->b_flags & B_ASYNC) { 2837 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR | B_RELBUF)) != 0) 2838 brelse(bp); 2839 else 2840 bqrelse(bp); 2841 } else { 2842 wakeup(bp); 2843 } 2844 splx(s); 2845 } 2846 2847 /* 2848 * This routine is called in lieu of iodone in the case of 2849 * incomplete I/O. This keeps the busy status for pages 2850 * consistant. 2851 */ 2852 void 2853 vfs_unbusy_pages(struct buf * bp) 2854 { 2855 int i; 2856 2857 runningbufwakeup(bp); 2858 if (bp->b_flags & B_VMIO) { 2859 struct vnode *vp = bp->b_vp; 2860 vm_object_t obj; 2861 2862 VOP_GETVOBJECT(vp, &obj); 2863 2864 for (i = 0; i < bp->b_npages; i++) { 2865 vm_page_t m = bp->b_pages[i]; 2866 2867 if (m == bogus_page) { 2868 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 2869 if (!m) { 2870 panic("vfs_unbusy_pages: page missing\n"); 2871 } 2872 bp->b_pages[i] = m; 2873 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 2874 } 2875 vm_object_pip_subtract(obj, 1); 2876 vm_page_flag_clear(m, PG_ZERO); 2877 vm_page_io_finish(m); 2878 } 2879 vm_object_pip_wakeupn(obj, 0); 2880 } 2881 } 2882 2883 /* 2884 * vfs_page_set_valid: 2885 * 2886 * Set the valid bits in a page based on the supplied offset. The 2887 * range is restricted to the buffer's size. 2888 * 2889 * This routine is typically called after a read completes. 2890 */ 2891 static void 2892 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m) 2893 { 2894 vm_ooffset_t soff, eoff; 2895 2896 /* 2897 * Start and end offsets in buffer. eoff - soff may not cross a 2898 * page boundry or cross the end of the buffer. The end of the 2899 * buffer, in this case, is our file EOF, not the allocation size 2900 * of the buffer. 2901 */ 2902 soff = off; 2903 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2904 if (eoff > bp->b_offset + bp->b_bcount) 2905 eoff = bp->b_offset + bp->b_bcount; 2906 2907 /* 2908 * Set valid range. This is typically the entire buffer and thus the 2909 * entire page. 2910 */ 2911 if (eoff > soff) { 2912 vm_page_set_validclean( 2913 m, 2914 (vm_offset_t) (soff & PAGE_MASK), 2915 (vm_offset_t) (eoff - soff) 2916 ); 2917 } 2918 } 2919 2920 /* 2921 * This routine is called before a device strategy routine. 2922 * It is used to tell the VM system that paging I/O is in 2923 * progress, and treat the pages associated with the buffer 2924 * almost as being PG_BUSY. Also the object paging_in_progress 2925 * flag is handled to make sure that the object doesn't become 2926 * inconsistant. 2927 * 2928 * Since I/O has not been initiated yet, certain buffer flags 2929 * such as B_ERROR or B_INVAL may be in an inconsistant state 2930 * and should be ignored. 2931 */ 2932 void 2933 vfs_busy_pages(struct buf * bp, int clear_modify) 2934 { 2935 int i, bogus; 2936 2937 if (bp->b_flags & B_VMIO) { 2938 struct vnode *vp = bp->b_vp; 2939 vm_object_t obj; 2940 vm_ooffset_t foff; 2941 2942 VOP_GETVOBJECT(vp, &obj); 2943 foff = bp->b_offset; 2944 KASSERT(bp->b_offset != NOOFFSET, 2945 ("vfs_busy_pages: no buffer offset")); 2946 vfs_setdirty(bp); 2947 2948 retry: 2949 for (i = 0; i < bp->b_npages; i++) { 2950 vm_page_t m = bp->b_pages[i]; 2951 if (vm_page_sleep_busy(m, FALSE, "vbpage")) 2952 goto retry; 2953 } 2954 2955 bogus = 0; 2956 for (i = 0; i < bp->b_npages; i++) { 2957 vm_page_t m = bp->b_pages[i]; 2958 2959 vm_page_flag_clear(m, PG_ZERO); 2960 if ((bp->b_flags & B_CLUSTER) == 0) { 2961 vm_object_pip_add(obj, 1); 2962 vm_page_io_start(m); 2963 } 2964 2965 /* 2966 * When readying a buffer for a read ( i.e 2967 * clear_modify == 0 ), it is important to do 2968 * bogus_page replacement for valid pages in 2969 * partially instantiated buffers. Partially 2970 * instantiated buffers can, in turn, occur when 2971 * reconstituting a buffer from its VM backing store 2972 * base. We only have to do this if B_CACHE is 2973 * clear ( which causes the I/O to occur in the 2974 * first place ). The replacement prevents the read 2975 * I/O from overwriting potentially dirty VM-backed 2976 * pages. XXX bogus page replacement is, uh, bogus. 2977 * It may not work properly with small-block devices. 2978 * We need to find a better way. 2979 */ 2980 2981 vm_page_protect(m, VM_PROT_NONE); 2982 if (clear_modify) 2983 vfs_page_set_valid(bp, foff, i, m); 2984 else if (m->valid == VM_PAGE_BITS_ALL && 2985 (bp->b_flags & B_CACHE) == 0) { 2986 bp->b_pages[i] = bogus_page; 2987 bogus++; 2988 } 2989 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2990 } 2991 if (bogus) 2992 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 2993 } 2994 } 2995 2996 /* 2997 * Tell the VM system that the pages associated with this buffer 2998 * are clean. This is used for delayed writes where the data is 2999 * going to go to disk eventually without additional VM intevention. 3000 * 3001 * Note that while we only really need to clean through to b_bcount, we 3002 * just go ahead and clean through to b_bufsize. 3003 */ 3004 static void 3005 vfs_clean_pages(struct buf * bp) 3006 { 3007 int i; 3008 3009 if (bp->b_flags & B_VMIO) { 3010 vm_ooffset_t foff; 3011 3012 foff = bp->b_offset; 3013 KASSERT(bp->b_offset != NOOFFSET, 3014 ("vfs_clean_pages: no buffer offset")); 3015 for (i = 0; i < bp->b_npages; i++) { 3016 vm_page_t m = bp->b_pages[i]; 3017 vm_ooffset_t noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3018 vm_ooffset_t eoff = noff; 3019 3020 if (eoff > bp->b_offset + bp->b_bufsize) 3021 eoff = bp->b_offset + bp->b_bufsize; 3022 vfs_page_set_valid(bp, foff, i, m); 3023 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3024 foff = noff; 3025 } 3026 } 3027 } 3028 3029 /* 3030 * vfs_bio_set_validclean: 3031 * 3032 * Set the range within the buffer to valid and clean. The range is 3033 * relative to the beginning of the buffer, b_offset. Note that b_offset 3034 * itself may be offset from the beginning of the first page. 3035 */ 3036 3037 void 3038 vfs_bio_set_validclean(struct buf *bp, int base, int size) 3039 { 3040 if (bp->b_flags & B_VMIO) { 3041 int i; 3042 int n; 3043 3044 /* 3045 * Fixup base to be relative to beginning of first page. 3046 * Set initial n to be the maximum number of bytes in the 3047 * first page that can be validated. 3048 */ 3049 3050 base += (bp->b_offset & PAGE_MASK); 3051 n = PAGE_SIZE - (base & PAGE_MASK); 3052 3053 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 3054 vm_page_t m = bp->b_pages[i]; 3055 3056 if (n > size) 3057 n = size; 3058 3059 vm_page_set_validclean(m, base & PAGE_MASK, n); 3060 base += n; 3061 size -= n; 3062 n = PAGE_SIZE; 3063 } 3064 } 3065 } 3066 3067 /* 3068 * vfs_bio_clrbuf: 3069 * 3070 * clear a buffer. This routine essentially fakes an I/O, so we need 3071 * to clear B_ERROR and B_INVAL. 3072 * 3073 * Note that while we only theoretically need to clear through b_bcount, 3074 * we go ahead and clear through b_bufsize. 3075 */ 3076 3077 void 3078 vfs_bio_clrbuf(struct buf *bp) 3079 { 3080 int i, mask = 0; 3081 caddr_t sa, ea; 3082 if ((bp->b_flags & (B_VMIO | B_MALLOC)) == B_VMIO) { 3083 bp->b_flags &= ~(B_INVAL|B_ERROR); 3084 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 3085 (bp->b_offset & PAGE_MASK) == 0) { 3086 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 3087 if ((bp->b_pages[0]->valid & mask) == mask) { 3088 bp->b_resid = 0; 3089 return; 3090 } 3091 if (((bp->b_pages[0]->flags & PG_ZERO) == 0) && 3092 ((bp->b_pages[0]->valid & mask) == 0)) { 3093 bzero(bp->b_data, bp->b_bufsize); 3094 bp->b_pages[0]->valid |= mask; 3095 bp->b_resid = 0; 3096 return; 3097 } 3098 } 3099 ea = sa = bp->b_data; 3100 for(i=0;i<bp->b_npages;i++,sa=ea) { 3101 int j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; 3102 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); 3103 ea = (caddr_t)(vm_offset_t)ulmin( 3104 (u_long)(vm_offset_t)ea, 3105 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); 3106 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 3107 if ((bp->b_pages[i]->valid & mask) == mask) 3108 continue; 3109 if ((bp->b_pages[i]->valid & mask) == 0) { 3110 if ((bp->b_pages[i]->flags & PG_ZERO) == 0) { 3111 bzero(sa, ea - sa); 3112 } 3113 } else { 3114 for (; sa < ea; sa += DEV_BSIZE, j++) { 3115 if (((bp->b_pages[i]->flags & PG_ZERO) == 0) && 3116 (bp->b_pages[i]->valid & (1<<j)) == 0) 3117 bzero(sa, DEV_BSIZE); 3118 } 3119 } 3120 bp->b_pages[i]->valid |= mask; 3121 vm_page_flag_clear(bp->b_pages[i], PG_ZERO); 3122 } 3123 bp->b_resid = 0; 3124 } else { 3125 clrbuf(bp); 3126 } 3127 } 3128 3129 /* 3130 * vm_hold_load_pages and vm_hold_unload pages get pages into 3131 * a buffers address space. The pages are anonymous and are 3132 * not associated with a file object. 3133 */ 3134 void 3135 vm_hold_load_pages(struct buf * bp, vm_offset_t from, vm_offset_t to) 3136 { 3137 vm_offset_t pg; 3138 vm_page_t p; 3139 int index; 3140 3141 to = round_page(to); 3142 from = round_page(from); 3143 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3144 3145 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3146 3147 tryagain: 3148 3149 /* 3150 * note: must allocate system pages since blocking here 3151 * could intefere with paging I/O, no matter which 3152 * process we are. 3153 */ 3154 p = vm_page_alloc(kernel_object, 3155 ((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 3156 VM_ALLOC_SYSTEM); 3157 if (!p) { 3158 vm_pageout_deficit += (to - from) >> PAGE_SHIFT; 3159 VM_WAIT; 3160 goto tryagain; 3161 } 3162 vm_page_wire(p); 3163 p->valid = VM_PAGE_BITS_ALL; 3164 vm_page_flag_clear(p, PG_ZERO); 3165 pmap_kenter(pg, VM_PAGE_TO_PHYS(p)); 3166 bp->b_pages[index] = p; 3167 vm_page_wakeup(p); 3168 } 3169 bp->b_npages = index; 3170 } 3171 3172 void 3173 vm_hold_free_pages(struct buf * bp, vm_offset_t from, vm_offset_t to) 3174 { 3175 vm_offset_t pg; 3176 vm_page_t p; 3177 int index, newnpages; 3178 3179 from = round_page(from); 3180 to = round_page(to); 3181 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3182 3183 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3184 p = bp->b_pages[index]; 3185 if (p && (index < bp->b_npages)) { 3186 if (p->busy) { 3187 printf("vm_hold_free_pages: blkno: %d, lblkno: %d\n", 3188 bp->b_blkno, bp->b_lblkno); 3189 } 3190 bp->b_pages[index] = NULL; 3191 pmap_kremove(pg); 3192 vm_page_busy(p); 3193 vm_page_unwire(p, 0); 3194 vm_page_free(p); 3195 } 3196 } 3197 bp->b_npages = newnpages; 3198 } 3199 3200 /* 3201 * Map an IO request into kernel virtual address space. 3202 * 3203 * All requests are (re)mapped into kernel VA space. 3204 * Notice that we use b_bufsize for the size of the buffer 3205 * to be mapped. b_bcount might be modified by the driver. 3206 */ 3207 int 3208 vmapbuf(struct buf *bp) 3209 { 3210 caddr_t addr, v, kva; 3211 vm_offset_t pa; 3212 int pidx; 3213 int i; 3214 struct vm_page *m; 3215 3216 if ((bp->b_flags & B_PHYS) == 0) 3217 panic("vmapbuf"); 3218 if (bp->b_bufsize < 0) 3219 return (-1); 3220 for (v = bp->b_saveaddr, 3221 addr = (caddr_t)trunc_page((vm_offset_t)bp->b_data), 3222 pidx = 0; 3223 addr < bp->b_data + bp->b_bufsize; 3224 addr += PAGE_SIZE, v += PAGE_SIZE, pidx++) { 3225 /* 3226 * Do the vm_fault if needed; do the copy-on-write thing 3227 * when reading stuff off device into memory. 3228 */ 3229 retry: 3230 i = vm_fault_quick((addr >= bp->b_data) ? addr : bp->b_data, 3231 (bp->b_flags&B_READ)?(VM_PROT_READ|VM_PROT_WRITE):VM_PROT_READ); 3232 if (i < 0) { 3233 for (i = 0; i < pidx; ++i) { 3234 vm_page_unhold(bp->b_pages[i]); 3235 bp->b_pages[i] = NULL; 3236 } 3237 return(-1); 3238 } 3239 3240 /* 3241 * WARNING! If sparc support is MFCd in the future this will 3242 * have to be changed from pmap_kextract() to pmap_extract() 3243 * ala -current. 3244 */ 3245 #ifdef __sparc64__ 3246 #error "If MFCing sparc support use pmap_extract" 3247 #endif 3248 pa = pmap_kextract((vm_offset_t)addr); 3249 if (pa == 0) { 3250 printf("vmapbuf: warning, race against user address during I/O"); 3251 goto retry; 3252 } 3253 m = PHYS_TO_VM_PAGE(pa); 3254 vm_page_hold(m); 3255 bp->b_pages[pidx] = m; 3256 } 3257 if (pidx > btoc(MAXPHYS)) 3258 panic("vmapbuf: mapped more than MAXPHYS"); 3259 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx); 3260 3261 kva = bp->b_saveaddr; 3262 bp->b_npages = pidx; 3263 bp->b_saveaddr = bp->b_data; 3264 bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK); 3265 return(0); 3266 } 3267 3268 /* 3269 * Free the io map PTEs associated with this IO operation. 3270 * We also invalidate the TLB entries and restore the original b_addr. 3271 */ 3272 void 3273 vunmapbuf(bp) 3274 register struct buf *bp; 3275 { 3276 int pidx; 3277 int npages; 3278 vm_page_t *m; 3279 3280 if ((bp->b_flags & B_PHYS) == 0) 3281 panic("vunmapbuf"); 3282 3283 npages = bp->b_npages; 3284 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), 3285 npages); 3286 m = bp->b_pages; 3287 for (pidx = 0; pidx < npages; pidx++) 3288 vm_page_unhold(*m++); 3289 3290 bp->b_data = bp->b_saveaddr; 3291 } 3292 3293 #include "opt_ddb.h" 3294 #ifdef DDB 3295 #include <ddb/ddb.h> 3296 3297 DB_SHOW_COMMAND(buffer, db_show_buffer) 3298 { 3299 /* get args */ 3300 struct buf *bp = (struct buf *)addr; 3301 3302 if (!have_addr) { 3303 db_printf("usage: show buffer <addr>\n"); 3304 return; 3305 } 3306 3307 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS); 3308 db_printf("b_error = %d, b_bufsize = %ld, b_bcount = %ld, " 3309 "b_resid = %ld\nb_dev = (%d,%d), b_data = %p, " 3310 "b_blkno = %d, b_pblkno = %d\n", 3311 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 3312 major(bp->b_dev), minor(bp->b_dev), 3313 bp->b_data, bp->b_blkno, bp->b_pblkno); 3314 if (bp->b_npages) { 3315 int i; 3316 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 3317 for (i = 0; i < bp->b_npages; i++) { 3318 vm_page_t m; 3319 m = bp->b_pages[i]; 3320 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 3321 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 3322 if ((i + 1) < bp->b_npages) 3323 db_printf(","); 3324 } 3325 db_printf("\n"); 3326 } 3327 } 3328 #endif /* DDB */ 3329