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 * $DragonFly: src/sys/kern/vfs_bio.c,v 1.11 2003/07/26 19:42:11 rob Exp $ 16 */ 17 18 /* 19 * this file contains a new buffer I/O scheme implementing a coherent 20 * VM object and buffer cache scheme. Pains have been taken to make 21 * sure that the performance degradation associated with schemes such 22 * as this is not realized. 23 * 24 * Author: John S. Dyson 25 * Significant help during the development and debugging phases 26 * had been provided by David Greenman, also of the FreeBSD core team. 27 * 28 * see man buf(9) for more info. 29 */ 30 31 #include <sys/param.h> 32 #include <sys/systm.h> 33 #include <sys/buf.h> 34 #include <sys/conf.h> 35 #include <sys/eventhandler.h> 36 #include <sys/lock.h> 37 #include <sys/malloc.h> 38 #include <sys/mount.h> 39 #include <sys/kernel.h> 40 #include <sys/kthread.h> 41 #include <sys/proc.h> 42 #include <sys/reboot.h> 43 #include <sys/resourcevar.h> 44 #include <sys/sysctl.h> 45 #include <sys/vmmeter.h> 46 #include <sys/vnode.h> 47 #include <sys/proc.h> 48 #include <vm/vm.h> 49 #include <vm/vm_param.h> 50 #include <vm/vm_kern.h> 51 #include <vm/vm_pageout.h> 52 #include <vm/vm_page.h> 53 #include <vm/vm_object.h> 54 #include <vm/vm_extern.h> 55 #include <vm/vm_map.h> 56 #include <sys/buf2.h> 57 #include <vm/vm_page2.h> 58 59 static MALLOC_DEFINE(M_BIOBUF, "BIO buffer", "BIO buffer"); 60 61 struct bio_ops bioops; /* I/O operation notification */ 62 63 struct buf *buf; /* buffer header pool */ 64 struct swqueue bswlist; 65 66 static void vm_hold_free_pages(struct buf * bp, vm_offset_t from, 67 vm_offset_t to); 68 static void vm_hold_load_pages(struct buf * bp, vm_offset_t from, 69 vm_offset_t to); 70 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, 71 int pageno, vm_page_t m); 72 static void vfs_clean_pages(struct buf * bp); 73 static void vfs_setdirty(struct buf *bp); 74 static void vfs_vmio_release(struct buf *bp); 75 static void vfs_backgroundwritedone(struct buf *bp); 76 static int flushbufqueues(void); 77 78 static int bd_request; 79 80 static void buf_daemon __P((void)); 81 /* 82 * bogus page -- for I/O to/from partially complete buffers 83 * this is a temporary solution to the problem, but it is not 84 * really that bad. it would be better to split the buffer 85 * for input in the case of buffers partially already in memory, 86 * but the code is intricate enough already. 87 */ 88 vm_page_t bogus_page; 89 int vmiodirenable = TRUE; 90 int runningbufspace; 91 static vm_offset_t bogus_offset; 92 93 static int bufspace, maxbufspace, 94 bufmallocspace, maxbufmallocspace, lobufspace, hibufspace; 95 static int bufreusecnt, bufdefragcnt, buffreekvacnt; 96 static int needsbuffer; 97 static int lorunningspace, hirunningspace, runningbufreq; 98 static int numdirtybuffers, lodirtybuffers, hidirtybuffers; 99 static int numfreebuffers, lofreebuffers, hifreebuffers; 100 static int getnewbufcalls; 101 static int getnewbufrestarts; 102 103 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, 104 &numdirtybuffers, 0, ""); 105 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, 106 &lodirtybuffers, 0, ""); 107 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, 108 &hidirtybuffers, 0, ""); 109 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, 110 &numfreebuffers, 0, ""); 111 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, 112 &lofreebuffers, 0, ""); 113 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, 114 &hifreebuffers, 0, ""); 115 SYSCTL_INT(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, 116 &runningbufspace, 0, ""); 117 SYSCTL_INT(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, 118 &lorunningspace, 0, ""); 119 SYSCTL_INT(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, 120 &hirunningspace, 0, ""); 121 SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, 122 &maxbufspace, 0, ""); 123 SYSCTL_INT(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, 124 &hibufspace, 0, ""); 125 SYSCTL_INT(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, 126 &lobufspace, 0, ""); 127 SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, 128 &bufspace, 0, ""); 129 SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, 130 &maxbufmallocspace, 0, ""); 131 SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, 132 &bufmallocspace, 0, ""); 133 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, 134 &getnewbufcalls, 0, ""); 135 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, 136 &getnewbufrestarts, 0, ""); 137 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, 138 &vmiodirenable, 0, ""); 139 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, 140 &bufdefragcnt, 0, ""); 141 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, 142 &buffreekvacnt, 0, ""); 143 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, 144 &bufreusecnt, 0, ""); 145 146 static int bufhashmask; 147 static LIST_HEAD(bufhashhdr, buf) *bufhashtbl, invalhash; 148 struct bqueues bufqueues[BUFFER_QUEUES] = { { 0 } }; 149 char *buf_wmesg = BUF_WMESG; 150 151 extern int vm_swap_size; 152 153 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 154 #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */ 155 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ 156 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 157 158 /* 159 * Buffer hash table code. Note that the logical block scans linearly, which 160 * gives us some L1 cache locality. 161 */ 162 163 static __inline 164 struct bufhashhdr * 165 bufhash(struct vnode *vnp, daddr_t bn) 166 { 167 return(&bufhashtbl[(((uintptr_t)(vnp) >> 7) + (int)bn) & bufhashmask]); 168 } 169 170 /* 171 * numdirtywakeup: 172 * 173 * If someone is blocked due to there being too many dirty buffers, 174 * and numdirtybuffers is now reasonable, wake them up. 175 */ 176 177 static __inline void 178 numdirtywakeup(int level) 179 { 180 if (numdirtybuffers <= level) { 181 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) { 182 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH; 183 wakeup(&needsbuffer); 184 } 185 } 186 } 187 188 /* 189 * bufspacewakeup: 190 * 191 * Called when buffer space is potentially available for recovery. 192 * getnewbuf() will block on this flag when it is unable to free 193 * sufficient buffer space. Buffer space becomes recoverable when 194 * bp's get placed back in the queues. 195 */ 196 197 static __inline void 198 bufspacewakeup(void) 199 { 200 /* 201 * If someone is waiting for BUF space, wake them up. Even 202 * though we haven't freed the kva space yet, the waiting 203 * process will be able to now. 204 */ 205 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) { 206 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE; 207 wakeup(&needsbuffer); 208 } 209 } 210 211 /* 212 * runningbufwakeup() - in-progress I/O accounting. 213 * 214 */ 215 static __inline void 216 runningbufwakeup(struct buf *bp) 217 { 218 if (bp->b_runningbufspace) { 219 runningbufspace -= bp->b_runningbufspace; 220 bp->b_runningbufspace = 0; 221 if (runningbufreq && runningbufspace <= lorunningspace) { 222 runningbufreq = 0; 223 wakeup(&runningbufreq); 224 } 225 } 226 } 227 228 /* 229 * bufcountwakeup: 230 * 231 * Called when a buffer has been added to one of the free queues to 232 * account for the buffer and to wakeup anyone waiting for free buffers. 233 * This typically occurs when large amounts of metadata are being handled 234 * by the buffer cache ( else buffer space runs out first, usually ). 235 */ 236 237 static __inline void 238 bufcountwakeup(void) 239 { 240 ++numfreebuffers; 241 if (needsbuffer) { 242 needsbuffer &= ~VFS_BIO_NEED_ANY; 243 if (numfreebuffers >= hifreebuffers) 244 needsbuffer &= ~VFS_BIO_NEED_FREE; 245 wakeup(&needsbuffer); 246 } 247 } 248 249 /* 250 * waitrunningbufspace() 251 * 252 * runningbufspace is a measure of the amount of I/O currently 253 * running. This routine is used in async-write situations to 254 * prevent creating huge backups of pending writes to a device. 255 * Only asynchronous writes are governed by this function. 256 * 257 * Reads will adjust runningbufspace, but will not block based on it. 258 * The read load has a side effect of reducing the allowed write load. 259 * 260 * This does NOT turn an async write into a sync write. It waits 261 * for earlier writes to complete and generally returns before the 262 * caller's write has reached the device. 263 */ 264 static __inline void 265 waitrunningbufspace(void) 266 { 267 while (runningbufspace > hirunningspace) { 268 int s; 269 270 s = splbio(); /* fix race against interrupt/biodone() */ 271 ++runningbufreq; 272 tsleep(&runningbufreq, 0, "wdrain", 0); 273 splx(s); 274 } 275 } 276 277 /* 278 * vfs_buf_test_cache: 279 * 280 * Called when a buffer is extended. This function clears the B_CACHE 281 * bit if the newly extended portion of the buffer does not contain 282 * valid data. 283 */ 284 static __inline__ 285 void 286 vfs_buf_test_cache(struct buf *bp, 287 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 288 vm_page_t m) 289 { 290 if (bp->b_flags & B_CACHE) { 291 int base = (foff + off) & PAGE_MASK; 292 if (vm_page_is_valid(m, base, size) == 0) 293 bp->b_flags &= ~B_CACHE; 294 } 295 } 296 297 static __inline__ 298 void 299 bd_wakeup(int dirtybuflevel) 300 { 301 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) { 302 bd_request = 1; 303 wakeup(&bd_request); 304 } 305 } 306 307 /* 308 * bd_speedup - speedup the buffer cache flushing code 309 */ 310 311 static __inline__ 312 void 313 bd_speedup(void) 314 { 315 bd_wakeup(1); 316 } 317 318 /* 319 * Initialize buffer headers and related structures. 320 */ 321 322 caddr_t 323 bufhashinit(caddr_t vaddr) 324 { 325 /* first, make a null hash table */ 326 for (bufhashmask = 8; bufhashmask < nbuf / 4; bufhashmask <<= 1) 327 ; 328 bufhashtbl = (void *)vaddr; 329 vaddr = vaddr + sizeof(*bufhashtbl) * bufhashmask; 330 --bufhashmask; 331 return(vaddr); 332 } 333 334 void 335 bufinit(void) 336 { 337 struct buf *bp; 338 int i; 339 340 TAILQ_INIT(&bswlist); 341 LIST_INIT(&invalhash); 342 lwkt_inittoken(&buftimetoken); 343 344 for (i = 0; i <= bufhashmask; i++) 345 LIST_INIT(&bufhashtbl[i]); 346 347 /* next, make a null set of free lists */ 348 for (i = 0; i < BUFFER_QUEUES; i++) 349 TAILQ_INIT(&bufqueues[i]); 350 351 /* finally, initialize each buffer header and stick on empty q */ 352 for (i = 0; i < nbuf; i++) { 353 bp = &buf[i]; 354 bzero(bp, sizeof *bp); 355 bp->b_flags = B_INVAL; /* we're just an empty header */ 356 bp->b_dev = NODEV; 357 bp->b_qindex = QUEUE_EMPTY; 358 bp->b_xflags = 0; 359 LIST_INIT(&bp->b_dep); 360 BUF_LOCKINIT(bp); 361 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 362 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 363 } 364 365 /* 366 * maxbufspace is the absolute maximum amount of buffer space we are 367 * allowed to reserve in KVM and in real terms. The absolute maximum 368 * is nominally used by buf_daemon. hibufspace is the nominal maximum 369 * used by most other processes. The differential is required to 370 * ensure that buf_daemon is able to run when other processes might 371 * be blocked waiting for buffer space. 372 * 373 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 374 * this may result in KVM fragmentation which is not handled optimally 375 * by the system. 376 */ 377 maxbufspace = nbuf * BKVASIZE; 378 hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 379 lobufspace = hibufspace - MAXBSIZE; 380 381 lorunningspace = 512 * 1024; 382 hirunningspace = 1024 * 1024; 383 384 /* 385 * Limit the amount of malloc memory since it is wired permanently into 386 * the kernel space. Even though this is accounted for in the buffer 387 * allocation, we don't want the malloced region to grow uncontrolled. 388 * The malloc scheme improves memory utilization significantly on average 389 * (small) directories. 390 */ 391 maxbufmallocspace = hibufspace / 20; 392 393 /* 394 * Reduce the chance of a deadlock occuring by limiting the number 395 * of delayed-write dirty buffers we allow to stack up. 396 */ 397 hidirtybuffers = nbuf / 4 + 20; 398 numdirtybuffers = 0; 399 /* 400 * To support extreme low-memory systems, make sure hidirtybuffers cannot 401 * eat up all available buffer space. This occurs when our minimum cannot 402 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 403 * BKVASIZE'd (8K) buffers. 404 */ 405 while (hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 406 hidirtybuffers >>= 1; 407 } 408 lodirtybuffers = hidirtybuffers / 2; 409 410 /* 411 * Try to keep the number of free buffers in the specified range, 412 * and give special processes (e.g. like buf_daemon) access to an 413 * emergency reserve. 414 */ 415 lofreebuffers = nbuf / 18 + 5; 416 hifreebuffers = 2 * lofreebuffers; 417 numfreebuffers = nbuf; 418 419 /* 420 * Maximum number of async ops initiated per buf_daemon loop. This is 421 * somewhat of a hack at the moment, we really need to limit ourselves 422 * based on the number of bytes of I/O in-transit that were initiated 423 * from buf_daemon. 424 */ 425 426 bogus_offset = kmem_alloc_pageable(kernel_map, PAGE_SIZE); 427 bogus_page = vm_page_alloc(kernel_object, 428 ((bogus_offset - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 429 VM_ALLOC_NORMAL); 430 vmstats.v_wire_count++; 431 432 } 433 434 /* 435 * bfreekva() - free the kva allocation for a buffer. 436 * 437 * Must be called at splbio() or higher as this is the only locking for 438 * buffer_map. 439 * 440 * Since this call frees up buffer space, we call bufspacewakeup(). 441 */ 442 static void 443 bfreekva(struct buf * bp) 444 { 445 if (bp->b_kvasize) { 446 ++buffreekvacnt; 447 vm_map_lock(buffer_map); 448 bufspace -= bp->b_kvasize; 449 vm_map_delete(buffer_map, 450 (vm_offset_t) bp->b_kvabase, 451 (vm_offset_t) bp->b_kvabase + bp->b_kvasize 452 ); 453 vm_map_unlock(buffer_map); 454 bp->b_kvasize = 0; 455 bufspacewakeup(); 456 } 457 } 458 459 /* 460 * bremfree: 461 * 462 * Remove the buffer from the appropriate free list. 463 */ 464 void 465 bremfree(struct buf * bp) 466 { 467 int s = splbio(); 468 int old_qindex = bp->b_qindex; 469 470 if (bp->b_qindex != QUEUE_NONE) { 471 KASSERT(BUF_REFCNT(bp) == 1, ("bremfree: bp %p not locked",bp)); 472 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 473 bp->b_qindex = QUEUE_NONE; 474 } else { 475 if (BUF_REFCNT(bp) <= 1) 476 panic("bremfree: removing a buffer not on a queue"); 477 } 478 479 /* 480 * Fixup numfreebuffers count. If the buffer is invalid or not 481 * delayed-write, and it was on the EMPTY, LRU, or AGE queues, 482 * the buffer was free and we must decrement numfreebuffers. 483 */ 484 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { 485 switch(old_qindex) { 486 case QUEUE_DIRTY: 487 case QUEUE_CLEAN: 488 case QUEUE_EMPTY: 489 case QUEUE_EMPTYKVA: 490 --numfreebuffers; 491 break; 492 default: 493 break; 494 } 495 } 496 splx(s); 497 } 498 499 500 /* 501 * Get a buffer with the specified data. Look in the cache first. We 502 * must clear B_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 503 * is set, the buffer is valid and we do not have to do anything ( see 504 * getblk() ). 505 */ 506 int 507 bread(struct vnode * vp, daddr_t blkno, int size, struct buf ** bpp) 508 { 509 struct buf *bp; 510 511 bp = getblk(vp, blkno, size, 0, 0); 512 *bpp = bp; 513 514 /* if not found in cache, do some I/O */ 515 if ((bp->b_flags & B_CACHE) == 0) { 516 KASSERT(!(bp->b_flags & B_ASYNC), ("bread: illegal async bp %p", bp)); 517 bp->b_flags |= B_READ; 518 bp->b_flags &= ~(B_ERROR | B_INVAL); 519 vfs_busy_pages(bp, 0); 520 VOP_STRATEGY(vp, bp); 521 return (biowait(bp)); 522 } 523 return (0); 524 } 525 526 /* 527 * Operates like bread, but also starts asynchronous I/O on 528 * read-ahead blocks. We must clear B_ERROR and B_INVAL prior 529 * to initiating I/O . If B_CACHE is set, the buffer is valid 530 * and we do not have to do anything. 531 */ 532 int 533 breadn(struct vnode * vp, daddr_t blkno, int size, daddr_t * rablkno, 534 int *rabsize, int cnt, struct buf ** bpp) 535 { 536 struct buf *bp, *rabp; 537 int i; 538 int rv = 0, readwait = 0; 539 540 *bpp = bp = getblk(vp, blkno, size, 0, 0); 541 542 /* if not found in cache, do some I/O */ 543 if ((bp->b_flags & B_CACHE) == 0) { 544 bp->b_flags |= B_READ; 545 bp->b_flags &= ~(B_ERROR | B_INVAL); 546 vfs_busy_pages(bp, 0); 547 VOP_STRATEGY(vp, bp); 548 ++readwait; 549 } 550 551 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 552 if (inmem(vp, *rablkno)) 553 continue; 554 rabp = getblk(vp, *rablkno, *rabsize, 0, 0); 555 556 if ((rabp->b_flags & B_CACHE) == 0) { 557 rabp->b_flags |= B_READ | B_ASYNC; 558 rabp->b_flags &= ~(B_ERROR | B_INVAL); 559 vfs_busy_pages(rabp, 0); 560 BUF_KERNPROC(rabp); 561 VOP_STRATEGY(vp, rabp); 562 } else { 563 brelse(rabp); 564 } 565 } 566 567 if (readwait) { 568 rv = biowait(bp); 569 } 570 return (rv); 571 } 572 573 /* 574 * Write, release buffer on completion. (Done by iodone 575 * if async). Do not bother writing anything if the buffer 576 * is invalid. 577 * 578 * Note that we set B_CACHE here, indicating that buffer is 579 * fully valid and thus cacheable. This is true even of NFS 580 * now so we set it generally. This could be set either here 581 * or in biodone() since the I/O is synchronous. We put it 582 * here. 583 */ 584 int 585 bwrite(struct buf * bp) 586 { 587 int oldflags, s; 588 struct buf *newbp; 589 590 if (bp->b_flags & B_INVAL) { 591 brelse(bp); 592 return (0); 593 } 594 595 oldflags = bp->b_flags; 596 597 if (BUF_REFCNT(bp) == 0) 598 panic("bwrite: buffer is not busy???"); 599 s = splbio(); 600 /* 601 * If a background write is already in progress, delay 602 * writing this block if it is asynchronous. Otherwise 603 * wait for the background write to complete. 604 */ 605 if (bp->b_xflags & BX_BKGRDINPROG) { 606 if (bp->b_flags & B_ASYNC) { 607 splx(s); 608 bdwrite(bp); 609 return (0); 610 } 611 bp->b_xflags |= BX_BKGRDWAIT; 612 tsleep(&bp->b_xflags, 0, "biord", 0); 613 if (bp->b_xflags & BX_BKGRDINPROG) 614 panic("bwrite: still writing"); 615 } 616 617 /* Mark the buffer clean */ 618 bundirty(bp); 619 620 /* 621 * If this buffer is marked for background writing and we 622 * do not have to wait for it, make a copy and write the 623 * copy so as to leave this buffer ready for further use. 624 * 625 * This optimization eats a lot of memory. If we have a page 626 * or buffer shortfull we can't do it. 627 */ 628 if ((bp->b_xflags & BX_BKGRDWRITE) && 629 (bp->b_flags & B_ASYNC) && 630 !vm_page_count_severe() && 631 !buf_dirty_count_severe()) { 632 if (bp->b_flags & B_CALL) 633 panic("bwrite: need chained iodone"); 634 635 /* get a new block */ 636 newbp = geteblk(bp->b_bufsize); 637 638 /* set it to be identical to the old block */ 639 memcpy(newbp->b_data, bp->b_data, bp->b_bufsize); 640 bgetvp(bp->b_vp, newbp); 641 newbp->b_lblkno = bp->b_lblkno; 642 newbp->b_blkno = bp->b_blkno; 643 newbp->b_offset = bp->b_offset; 644 newbp->b_iodone = vfs_backgroundwritedone; 645 newbp->b_flags |= B_ASYNC | B_CALL; 646 newbp->b_flags &= ~B_INVAL; 647 648 /* move over the dependencies */ 649 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_movedeps) 650 (*bioops.io_movedeps)(bp, newbp); 651 652 /* 653 * Initiate write on the copy, release the original to 654 * the B_LOCKED queue so that it cannot go away until 655 * the background write completes. If not locked it could go 656 * away and then be reconstituted while it was being written. 657 * If the reconstituted buffer were written, we could end up 658 * with two background copies being written at the same time. 659 */ 660 bp->b_xflags |= BX_BKGRDINPROG; 661 bp->b_flags |= B_LOCKED; 662 bqrelse(bp); 663 bp = newbp; 664 } 665 666 bp->b_flags &= ~(B_READ | B_DONE | B_ERROR); 667 bp->b_flags |= B_WRITEINPROG | B_CACHE; 668 669 bp->b_vp->v_numoutput++; 670 vfs_busy_pages(bp, 1); 671 672 /* 673 * Normal bwrites pipeline writes 674 */ 675 bp->b_runningbufspace = bp->b_bufsize; 676 runningbufspace += bp->b_runningbufspace; 677 678 splx(s); 679 if (oldflags & B_ASYNC) 680 BUF_KERNPROC(bp); 681 VOP_STRATEGY(bp->b_vp, bp); 682 683 if ((oldflags & B_ASYNC) == 0) { 684 int rtval = biowait(bp); 685 brelse(bp); 686 return (rtval); 687 } else if ((oldflags & B_NOWDRAIN) == 0) { 688 /* 689 * don't allow the async write to saturate the I/O 690 * system. Deadlocks can occur only if a device strategy 691 * routine (like in VN) turns around and issues another 692 * high-level write, in which case B_NOWDRAIN is expected 693 * to be set. Otherwise we will not deadlock here because 694 * we are blocking waiting for I/O that is already in-progress 695 * to complete. 696 */ 697 waitrunningbufspace(); 698 } 699 700 return (0); 701 } 702 703 /* 704 * Complete a background write started from bwrite. 705 */ 706 static void 707 vfs_backgroundwritedone(bp) 708 struct buf *bp; 709 { 710 struct buf *origbp; 711 712 /* 713 * Find the original buffer that we are writing. 714 */ 715 if ((origbp = gbincore(bp->b_vp, bp->b_lblkno)) == NULL) 716 panic("backgroundwritedone: lost buffer"); 717 /* 718 * Process dependencies then return any unfinished ones. 719 */ 720 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_complete) 721 (*bioops.io_complete)(bp); 722 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_movedeps) 723 (*bioops.io_movedeps)(bp, origbp); 724 /* 725 * Clear the BX_BKGRDINPROG flag in the original buffer 726 * and awaken it if it is waiting for the write to complete. 727 * If BX_BKGRDINPROG is not set in the original buffer it must 728 * have been released and re-instantiated - which is not legal. 729 */ 730 KASSERT((origbp->b_xflags & BX_BKGRDINPROG), ("backgroundwritedone: lost buffer2")); 731 origbp->b_xflags &= ~BX_BKGRDINPROG; 732 if (origbp->b_xflags & BX_BKGRDWAIT) { 733 origbp->b_xflags &= ~BX_BKGRDWAIT; 734 wakeup(&origbp->b_xflags); 735 } 736 /* 737 * Clear the B_LOCKED flag and remove it from the locked 738 * queue if it currently resides there. 739 */ 740 origbp->b_flags &= ~B_LOCKED; 741 if (BUF_LOCK(origbp, LK_EXCLUSIVE | LK_NOWAIT) == 0) { 742 bremfree(origbp); 743 bqrelse(origbp); 744 } 745 /* 746 * This buffer is marked B_NOCACHE, so when it is released 747 * by biodone, it will be tossed. We mark it with B_READ 748 * to avoid biodone doing a second vwakeup. 749 */ 750 bp->b_flags |= B_NOCACHE | B_READ; 751 bp->b_flags &= ~(B_CACHE | B_CALL | B_DONE); 752 bp->b_iodone = 0; 753 biodone(bp); 754 } 755 756 /* 757 * Delayed write. (Buffer is marked dirty). Do not bother writing 758 * anything if the buffer is marked invalid. 759 * 760 * Note that since the buffer must be completely valid, we can safely 761 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 762 * biodone() in order to prevent getblk from writing the buffer 763 * out synchronously. 764 */ 765 void 766 bdwrite(struct buf * bp) 767 { 768 if (BUF_REFCNT(bp) == 0) 769 panic("bdwrite: buffer is not busy"); 770 771 if (bp->b_flags & B_INVAL) { 772 brelse(bp); 773 return; 774 } 775 bdirty(bp); 776 777 /* 778 * Set B_CACHE, indicating that the buffer is fully valid. This is 779 * true even of NFS now. 780 */ 781 bp->b_flags |= B_CACHE; 782 783 /* 784 * This bmap keeps the system from needing to do the bmap later, 785 * perhaps when the system is attempting to do a sync. Since it 786 * is likely that the indirect block -- or whatever other datastructure 787 * that the filesystem needs is still in memory now, it is a good 788 * thing to do this. Note also, that if the pageout daemon is 789 * requesting a sync -- there might not be enough memory to do 790 * the bmap then... So, this is important to do. 791 */ 792 if (bp->b_lblkno == bp->b_blkno) { 793 VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 794 } 795 796 /* 797 * Set the *dirty* buffer range based upon the VM system dirty pages. 798 */ 799 vfs_setdirty(bp); 800 801 /* 802 * We need to do this here to satisfy the vnode_pager and the 803 * pageout daemon, so that it thinks that the pages have been 804 * "cleaned". Note that since the pages are in a delayed write 805 * buffer -- the VFS layer "will" see that the pages get written 806 * out on the next sync, or perhaps the cluster will be completed. 807 */ 808 vfs_clean_pages(bp); 809 bqrelse(bp); 810 811 /* 812 * Wakeup the buffer flushing daemon if we have a lot of dirty 813 * buffers (midpoint between our recovery point and our stall 814 * point). 815 */ 816 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 817 818 /* 819 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 820 * due to the softdep code. 821 */ 822 } 823 824 /* 825 * bdirty: 826 * 827 * Turn buffer into delayed write request. We must clear B_READ and 828 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 829 * itself to properly update it in the dirty/clean lists. We mark it 830 * B_DONE to ensure that any asynchronization of the buffer properly 831 * clears B_DONE ( else a panic will occur later ). 832 * 833 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 834 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 835 * should only be called if the buffer is known-good. 836 * 837 * Since the buffer is not on a queue, we do not update the numfreebuffers 838 * count. 839 * 840 * Must be called at splbio(). 841 * The buffer must be on QUEUE_NONE. 842 */ 843 void 844 bdirty(bp) 845 struct buf *bp; 846 { 847 KASSERT(bp->b_qindex == QUEUE_NONE, ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 848 bp->b_flags &= ~(B_READ|B_RELBUF); 849 850 if ((bp->b_flags & B_DELWRI) == 0) { 851 bp->b_flags |= B_DONE | B_DELWRI; 852 reassignbuf(bp, bp->b_vp); 853 ++numdirtybuffers; 854 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 855 } 856 } 857 858 /* 859 * bundirty: 860 * 861 * Clear B_DELWRI for buffer. 862 * 863 * Since the buffer is not on a queue, we do not update the numfreebuffers 864 * count. 865 * 866 * Must be called at splbio(). 867 * The buffer must be on QUEUE_NONE. 868 */ 869 870 void 871 bundirty(bp) 872 struct buf *bp; 873 { 874 KASSERT(bp->b_qindex == QUEUE_NONE, ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 875 876 if (bp->b_flags & B_DELWRI) { 877 bp->b_flags &= ~B_DELWRI; 878 reassignbuf(bp, bp->b_vp); 879 --numdirtybuffers; 880 numdirtywakeup(lodirtybuffers); 881 } 882 /* 883 * Since it is now being written, we can clear its deferred write flag. 884 */ 885 bp->b_flags &= ~B_DEFERRED; 886 } 887 888 /* 889 * bawrite: 890 * 891 * Asynchronous write. Start output on a buffer, but do not wait for 892 * it to complete. The buffer is released when the output completes. 893 * 894 * bwrite() ( or the VOP routine anyway ) is responsible for handling 895 * B_INVAL buffers. Not us. 896 */ 897 void 898 bawrite(struct buf * bp) 899 { 900 bp->b_flags |= B_ASYNC; 901 (void) VOP_BWRITE(bp->b_vp, bp); 902 } 903 904 /* 905 * bowrite: 906 * 907 * Ordered write. Start output on a buffer, and flag it so that the 908 * device will write it in the order it was queued. The buffer is 909 * released when the output completes. bwrite() ( or the VOP routine 910 * anyway ) is responsible for handling B_INVAL buffers. 911 */ 912 int 913 bowrite(struct buf * bp) 914 { 915 bp->b_flags |= B_ORDERED | B_ASYNC; 916 return (VOP_BWRITE(bp->b_vp, bp)); 917 } 918 919 /* 920 * bwillwrite: 921 * 922 * Called prior to the locking of any vnodes when we are expecting to 923 * write. We do not want to starve the buffer cache with too many 924 * dirty buffers so we block here. By blocking prior to the locking 925 * of any vnodes we attempt to avoid the situation where a locked vnode 926 * prevents the various system daemons from flushing related buffers. 927 */ 928 929 void 930 bwillwrite(void) 931 { 932 if (numdirtybuffers >= hidirtybuffers) { 933 int s; 934 935 s = splbio(); 936 while (numdirtybuffers >= hidirtybuffers) { 937 bd_wakeup(1); 938 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH; 939 tsleep(&needsbuffer, 0, "flswai", 0); 940 } 941 splx(s); 942 } 943 } 944 945 /* 946 * Return true if we have too many dirty buffers. 947 */ 948 int 949 buf_dirty_count_severe(void) 950 { 951 return(numdirtybuffers >= hidirtybuffers); 952 } 953 954 /* 955 * brelse: 956 * 957 * Release a busy buffer and, if requested, free its resources. The 958 * buffer will be stashed in the appropriate bufqueue[] allowing it 959 * to be accessed later as a cache entity or reused for other purposes. 960 */ 961 void 962 brelse(struct buf * bp) 963 { 964 int s; 965 966 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 967 968 s = splbio(); 969 970 if (bp->b_flags & B_LOCKED) 971 bp->b_flags &= ~B_ERROR; 972 973 if ((bp->b_flags & (B_READ | B_ERROR | B_INVAL)) == B_ERROR) { 974 /* 975 * Failed write, redirty. Must clear B_ERROR to prevent 976 * pages from being scrapped. If B_INVAL is set then 977 * this case is not run and the next case is run to 978 * destroy the buffer. B_INVAL can occur if the buffer 979 * is outside the range supported by the underlying device. 980 */ 981 bp->b_flags &= ~B_ERROR; 982 bdirty(bp); 983 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR | B_FREEBUF)) || 984 (bp->b_bufsize <= 0)) { 985 /* 986 * Either a failed I/O or we were asked to free or not 987 * cache the buffer. 988 */ 989 bp->b_flags |= B_INVAL; 990 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_deallocate) 991 (*bioops.io_deallocate)(bp); 992 if (bp->b_flags & B_DELWRI) { 993 --numdirtybuffers; 994 numdirtywakeup(lodirtybuffers); 995 } 996 bp->b_flags &= ~(B_DELWRI | B_CACHE | B_FREEBUF); 997 if ((bp->b_flags & B_VMIO) == 0) { 998 if (bp->b_bufsize) 999 allocbuf(bp, 0); 1000 if (bp->b_vp) 1001 brelvp(bp); 1002 } 1003 } 1004 1005 /* 1006 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1007 * is called with B_DELWRI set, the underlying pages may wind up 1008 * getting freed causing a previous write (bdwrite()) to get 'lost' 1009 * because pages associated with a B_DELWRI bp are marked clean. 1010 * 1011 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1012 * if B_DELWRI is set. 1013 * 1014 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1015 * on pages to return pages to the VM page queues. 1016 */ 1017 if (bp->b_flags & B_DELWRI) 1018 bp->b_flags &= ~B_RELBUF; 1019 else if (vm_page_count_severe() && !(bp->b_xflags & BX_BKGRDINPROG)) 1020 bp->b_flags |= B_RELBUF; 1021 1022 /* 1023 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1024 * constituted, not even NFS buffers now. Two flags effect this. If 1025 * B_INVAL, the struct buf is invalidated but the VM object is kept 1026 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1027 * 1028 * If B_ERROR or B_NOCACHE is set, pages in the VM object will be 1029 * invalidated. B_ERROR cannot be set for a failed write unless the 1030 * buffer is also B_INVAL because it hits the re-dirtying code above. 1031 * 1032 * Normally we can do this whether a buffer is B_DELWRI or not. If 1033 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1034 * the commit state and we cannot afford to lose the buffer. If the 1035 * buffer has a background write in progress, we need to keep it 1036 * around to prevent it from being reconstituted and starting a second 1037 * background write. 1038 */ 1039 if ((bp->b_flags & B_VMIO) 1040 && !(bp->b_vp->v_tag == VT_NFS && 1041 !vn_isdisk(bp->b_vp, NULL) && 1042 (bp->b_flags & B_DELWRI)) 1043 ) { 1044 1045 int i, j, resid; 1046 vm_page_t m; 1047 off_t foff; 1048 vm_pindex_t poff; 1049 vm_object_t obj; 1050 struct vnode *vp; 1051 1052 vp = bp->b_vp; 1053 1054 /* 1055 * Get the base offset and length of the buffer. Note that 1056 * in the VMIO case if the buffer block size is not 1057 * page-aligned then b_data pointer may not be page-aligned. 1058 * But our b_pages[] array *IS* page aligned. 1059 * 1060 * block sizes less then DEV_BSIZE (usually 512) are not 1061 * supported due to the page granularity bits (m->valid, 1062 * m->dirty, etc...). 1063 * 1064 * See man buf(9) for more information 1065 */ 1066 1067 resid = bp->b_bufsize; 1068 foff = bp->b_offset; 1069 1070 for (i = 0; i < bp->b_npages; i++) { 1071 m = bp->b_pages[i]; 1072 vm_page_flag_clear(m, PG_ZERO); 1073 /* 1074 * If we hit a bogus page, fixup *all* of them 1075 * now. 1076 */ 1077 if (m == bogus_page) { 1078 VOP_GETVOBJECT(vp, &obj); 1079 poff = OFF_TO_IDX(bp->b_offset); 1080 1081 for (j = i; j < bp->b_npages; j++) { 1082 vm_page_t mtmp; 1083 1084 mtmp = bp->b_pages[j]; 1085 if (mtmp == bogus_page) { 1086 mtmp = vm_page_lookup(obj, poff + j); 1087 if (!mtmp) { 1088 panic("brelse: page missing\n"); 1089 } 1090 bp->b_pages[j] = mtmp; 1091 } 1092 } 1093 1094 if ((bp->b_flags & B_INVAL) == 0) { 1095 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 1096 } 1097 m = bp->b_pages[i]; 1098 } 1099 if (bp->b_flags & (B_NOCACHE|B_ERROR)) { 1100 int poffset = foff & PAGE_MASK; 1101 int presid = resid > (PAGE_SIZE - poffset) ? 1102 (PAGE_SIZE - poffset) : resid; 1103 1104 KASSERT(presid >= 0, ("brelse: extra page")); 1105 vm_page_set_invalid(m, poffset, presid); 1106 } 1107 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1108 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1109 } 1110 1111 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1112 vfs_vmio_release(bp); 1113 1114 } else if (bp->b_flags & B_VMIO) { 1115 1116 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1117 vfs_vmio_release(bp); 1118 1119 } 1120 1121 if (bp->b_qindex != QUEUE_NONE) 1122 panic("brelse: free buffer onto another queue???"); 1123 if (BUF_REFCNT(bp) > 1) { 1124 /* Temporary panic to verify exclusive locking */ 1125 /* This panic goes away when we allow shared refs */ 1126 panic("brelse: multiple refs"); 1127 /* do not release to free list */ 1128 BUF_UNLOCK(bp); 1129 splx(s); 1130 return; 1131 } 1132 1133 /* enqueue */ 1134 1135 /* buffers with no memory */ 1136 if (bp->b_bufsize == 0) { 1137 bp->b_flags |= B_INVAL; 1138 bp->b_xflags &= ~BX_BKGRDWRITE; 1139 if (bp->b_xflags & BX_BKGRDINPROG) 1140 panic("losing buffer 1"); 1141 if (bp->b_kvasize) { 1142 bp->b_qindex = QUEUE_EMPTYKVA; 1143 } else { 1144 bp->b_qindex = QUEUE_EMPTY; 1145 } 1146 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1147 LIST_REMOVE(bp, b_hash); 1148 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1149 bp->b_dev = NODEV; 1150 /* buffers with junk contents */ 1151 } else if (bp->b_flags & (B_ERROR | B_INVAL | B_NOCACHE | B_RELBUF)) { 1152 bp->b_flags |= B_INVAL; 1153 bp->b_xflags &= ~BX_BKGRDWRITE; 1154 if (bp->b_xflags & BX_BKGRDINPROG) 1155 panic("losing buffer 2"); 1156 bp->b_qindex = QUEUE_CLEAN; 1157 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1158 LIST_REMOVE(bp, b_hash); 1159 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1160 bp->b_dev = NODEV; 1161 1162 /* buffers that are locked */ 1163 } else if (bp->b_flags & B_LOCKED) { 1164 bp->b_qindex = QUEUE_LOCKED; 1165 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LOCKED], bp, b_freelist); 1166 1167 /* remaining buffers */ 1168 } else { 1169 switch(bp->b_flags & (B_DELWRI|B_AGE)) { 1170 case B_DELWRI | B_AGE: 1171 bp->b_qindex = QUEUE_DIRTY; 1172 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_DIRTY], bp, b_freelist); 1173 break; 1174 case B_DELWRI: 1175 bp->b_qindex = QUEUE_DIRTY; 1176 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist); 1177 break; 1178 case B_AGE: 1179 bp->b_qindex = QUEUE_CLEAN; 1180 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1181 break; 1182 default: 1183 bp->b_qindex = QUEUE_CLEAN; 1184 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1185 break; 1186 } 1187 } 1188 1189 /* 1190 * If B_INVAL, clear B_DELWRI. We've already placed the buffer 1191 * on the correct queue. 1192 */ 1193 if ((bp->b_flags & (B_INVAL|B_DELWRI)) == (B_INVAL|B_DELWRI)) 1194 bundirty(bp); 1195 1196 /* 1197 * Fixup numfreebuffers count. The bp is on an appropriate queue 1198 * unless locked. We then bump numfreebuffers if it is not B_DELWRI. 1199 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1200 * if B_INVAL is set ). 1201 */ 1202 1203 if ((bp->b_flags & B_LOCKED) == 0 && !(bp->b_flags & B_DELWRI)) 1204 bufcountwakeup(); 1205 1206 /* 1207 * Something we can maybe free or reuse 1208 */ 1209 if (bp->b_bufsize || bp->b_kvasize) 1210 bufspacewakeup(); 1211 1212 /* unlock */ 1213 BUF_UNLOCK(bp); 1214 bp->b_flags &= ~(B_ORDERED | B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | 1215 B_DIRECT | B_NOWDRAIN); 1216 splx(s); 1217 } 1218 1219 /* 1220 * Release a buffer back to the appropriate queue but do not try to free 1221 * it. The buffer is expected to be used again soon. 1222 * 1223 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1224 * biodone() to requeue an async I/O on completion. It is also used when 1225 * known good buffers need to be requeued but we think we may need the data 1226 * again soon. 1227 * 1228 * XXX we should be able to leave the B_RELBUF hint set on completion. 1229 */ 1230 void 1231 bqrelse(struct buf * bp) 1232 { 1233 int s; 1234 1235 s = splbio(); 1236 1237 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1238 1239 if (bp->b_qindex != QUEUE_NONE) 1240 panic("bqrelse: free buffer onto another queue???"); 1241 if (BUF_REFCNT(bp) > 1) { 1242 /* do not release to free list */ 1243 panic("bqrelse: multiple refs"); 1244 BUF_UNLOCK(bp); 1245 splx(s); 1246 return; 1247 } 1248 if (bp->b_flags & B_LOCKED) { 1249 bp->b_flags &= ~B_ERROR; 1250 bp->b_qindex = QUEUE_LOCKED; 1251 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LOCKED], bp, b_freelist); 1252 /* buffers with stale but valid contents */ 1253 } else if (bp->b_flags & B_DELWRI) { 1254 bp->b_qindex = QUEUE_DIRTY; 1255 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist); 1256 } else if (vm_page_count_severe()) { 1257 /* 1258 * We are too low on memory, we have to try to free the 1259 * buffer (most importantly: the wired pages making up its 1260 * backing store) *now*. 1261 */ 1262 splx(s); 1263 brelse(bp); 1264 return; 1265 } else { 1266 bp->b_qindex = QUEUE_CLEAN; 1267 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1268 } 1269 1270 if ((bp->b_flags & B_LOCKED) == 0 && 1271 ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI))) { 1272 bufcountwakeup(); 1273 } 1274 1275 /* 1276 * Something we can maybe free or reuse. 1277 */ 1278 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1279 bufspacewakeup(); 1280 1281 /* unlock */ 1282 BUF_UNLOCK(bp); 1283 bp->b_flags &= ~(B_ORDERED | B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1284 splx(s); 1285 } 1286 1287 static void 1288 vfs_vmio_release(bp) 1289 struct buf *bp; 1290 { 1291 int i, s; 1292 vm_page_t m; 1293 1294 s = splvm(); 1295 for (i = 0; i < bp->b_npages; i++) { 1296 m = bp->b_pages[i]; 1297 bp->b_pages[i] = NULL; 1298 /* 1299 * In order to keep page LRU ordering consistent, put 1300 * everything on the inactive queue. 1301 */ 1302 vm_page_unwire(m, 0); 1303 /* 1304 * We don't mess with busy pages, it is 1305 * the responsibility of the process that 1306 * busied the pages to deal with them. 1307 */ 1308 if ((m->flags & PG_BUSY) || (m->busy != 0)) 1309 continue; 1310 1311 if (m->wire_count == 0) { 1312 vm_page_flag_clear(m, PG_ZERO); 1313 /* 1314 * Might as well free the page if we can and it has 1315 * no valid data. We also free the page if the 1316 * buffer was used for direct I/O. 1317 */ 1318 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && m->hold_count == 0) { 1319 vm_page_busy(m); 1320 vm_page_protect(m, VM_PROT_NONE); 1321 vm_page_free(m); 1322 } else if (bp->b_flags & B_DIRECT) { 1323 vm_page_try_to_free(m); 1324 } else if (vm_page_count_severe()) { 1325 vm_page_try_to_cache(m); 1326 } 1327 } 1328 } 1329 splx(s); 1330 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages); 1331 if (bp->b_bufsize) { 1332 bufspacewakeup(); 1333 bp->b_bufsize = 0; 1334 } 1335 bp->b_npages = 0; 1336 bp->b_flags &= ~B_VMIO; 1337 if (bp->b_vp) 1338 brelvp(bp); 1339 } 1340 1341 /* 1342 * Check to see if a block is currently memory resident. 1343 */ 1344 struct buf * 1345 gbincore(struct vnode * vp, daddr_t blkno) 1346 { 1347 struct buf *bp; 1348 struct bufhashhdr *bh; 1349 1350 bh = bufhash(vp, blkno); 1351 1352 /* Search hash chain */ 1353 LIST_FOREACH(bp, bh, b_hash) { 1354 /* hit */ 1355 if (bp->b_vp == vp && bp->b_lblkno == blkno && 1356 (bp->b_flags & B_INVAL) == 0) { 1357 break; 1358 } 1359 } 1360 return (bp); 1361 } 1362 1363 /* 1364 * vfs_bio_awrite: 1365 * 1366 * Implement clustered async writes for clearing out B_DELWRI buffers. 1367 * This is much better then the old way of writing only one buffer at 1368 * a time. Note that we may not be presented with the buffers in the 1369 * correct order, so we search for the cluster in both directions. 1370 */ 1371 int 1372 vfs_bio_awrite(struct buf * bp) 1373 { 1374 int i; 1375 int j; 1376 daddr_t lblkno = bp->b_lblkno; 1377 struct vnode *vp = bp->b_vp; 1378 int s; 1379 int ncl; 1380 struct buf *bpa; 1381 int nwritten; 1382 int size; 1383 int maxcl; 1384 1385 s = splbio(); 1386 /* 1387 * right now we support clustered writing only to regular files. If 1388 * we find a clusterable block we could be in the middle of a cluster 1389 * rather then at the beginning. 1390 */ 1391 if ((vp->v_type == VREG) && 1392 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1393 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1394 1395 size = vp->v_mount->mnt_stat.f_iosize; 1396 maxcl = MAXPHYS / size; 1397 1398 for (i = 1; i < maxcl; i++) { 1399 if ((bpa = gbincore(vp, lblkno + i)) && 1400 BUF_REFCNT(bpa) == 0 && 1401 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == 1402 (B_DELWRI | B_CLUSTEROK)) && 1403 (bpa->b_bufsize == size)) { 1404 if ((bpa->b_blkno == bpa->b_lblkno) || 1405 (bpa->b_blkno != 1406 bp->b_blkno + ((i * size) >> DEV_BSHIFT))) 1407 break; 1408 } else { 1409 break; 1410 } 1411 } 1412 for (j = 1; i + j <= maxcl && j <= lblkno; j++) { 1413 if ((bpa = gbincore(vp, lblkno - j)) && 1414 BUF_REFCNT(bpa) == 0 && 1415 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == 1416 (B_DELWRI | B_CLUSTEROK)) && 1417 (bpa->b_bufsize == size)) { 1418 if ((bpa->b_blkno == bpa->b_lblkno) || 1419 (bpa->b_blkno != 1420 bp->b_blkno - ((j * size) >> DEV_BSHIFT))) 1421 break; 1422 } else { 1423 break; 1424 } 1425 } 1426 --j; 1427 ncl = i + j; 1428 /* 1429 * this is a possible cluster write 1430 */ 1431 if (ncl != 1) { 1432 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl); 1433 splx(s); 1434 return nwritten; 1435 } 1436 } 1437 1438 BUF_LOCK(bp, LK_EXCLUSIVE); 1439 bremfree(bp); 1440 bp->b_flags |= B_ASYNC; 1441 1442 splx(s); 1443 /* 1444 * default (old) behavior, writing out only one block 1445 * 1446 * XXX returns b_bufsize instead of b_bcount for nwritten? 1447 */ 1448 nwritten = bp->b_bufsize; 1449 (void) VOP_BWRITE(bp->b_vp, bp); 1450 1451 return nwritten; 1452 } 1453 1454 /* 1455 * getnewbuf: 1456 * 1457 * Find and initialize a new buffer header, freeing up existing buffers 1458 * in the bufqueues as necessary. The new buffer is returned locked. 1459 * 1460 * Important: B_INVAL is not set. If the caller wishes to throw the 1461 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1462 * 1463 * We block if: 1464 * We have insufficient buffer headers 1465 * We have insufficient buffer space 1466 * buffer_map is too fragmented ( space reservation fails ) 1467 * If we have to flush dirty buffers ( but we try to avoid this ) 1468 * 1469 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1470 * Instead we ask the buf daemon to do it for us. We attempt to 1471 * avoid piecemeal wakeups of the pageout daemon. 1472 */ 1473 1474 static struct buf * 1475 getnewbuf(int slpflag, int slptimeo, int size, int maxsize) 1476 { 1477 struct buf *bp; 1478 struct buf *nbp; 1479 int defrag = 0; 1480 int nqindex; 1481 static int flushingbufs; 1482 1483 /* 1484 * We can't afford to block since we might be holding a vnode lock, 1485 * which may prevent system daemons from running. We deal with 1486 * low-memory situations by proactively returning memory and running 1487 * async I/O rather then sync I/O. 1488 */ 1489 1490 ++getnewbufcalls; 1491 --getnewbufrestarts; 1492 restart: 1493 ++getnewbufrestarts; 1494 1495 /* 1496 * Setup for scan. If we do not have enough free buffers, 1497 * we setup a degenerate case that immediately fails. Note 1498 * that if we are specially marked process, we are allowed to 1499 * dip into our reserves. 1500 * 1501 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 1502 * 1503 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 1504 * However, there are a number of cases (defragging, reusing, ...) 1505 * where we cannot backup. 1506 */ 1507 nqindex = QUEUE_EMPTYKVA; 1508 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 1509 1510 if (nbp == NULL) { 1511 /* 1512 * If no EMPTYKVA buffers and we are either 1513 * defragging or reusing, locate a CLEAN buffer 1514 * to free or reuse. If bufspace useage is low 1515 * skip this step so we can allocate a new buffer. 1516 */ 1517 if (defrag || bufspace >= lobufspace) { 1518 nqindex = QUEUE_CLEAN; 1519 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 1520 } 1521 1522 /* 1523 * If we could not find or were not allowed to reuse a 1524 * CLEAN buffer, check to see if it is ok to use an EMPTY 1525 * buffer. We can only use an EMPTY buffer if allocating 1526 * its KVA would not otherwise run us out of buffer space. 1527 */ 1528 if (nbp == NULL && defrag == 0 && 1529 bufspace + maxsize < hibufspace) { 1530 nqindex = QUEUE_EMPTY; 1531 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1532 } 1533 } 1534 1535 /* 1536 * Run scan, possibly freeing data and/or kva mappings on the fly 1537 * depending. 1538 */ 1539 1540 while ((bp = nbp) != NULL) { 1541 int qindex = nqindex; 1542 1543 /* 1544 * Calculate next bp ( we can only use it if we do not block 1545 * or do other fancy things ). 1546 */ 1547 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 1548 switch(qindex) { 1549 case QUEUE_EMPTY: 1550 nqindex = QUEUE_EMPTYKVA; 1551 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]))) 1552 break; 1553 /* fall through */ 1554 case QUEUE_EMPTYKVA: 1555 nqindex = QUEUE_CLEAN; 1556 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]))) 1557 break; 1558 /* fall through */ 1559 case QUEUE_CLEAN: 1560 /* 1561 * nbp is NULL. 1562 */ 1563 break; 1564 } 1565 } 1566 1567 /* 1568 * Sanity Checks 1569 */ 1570 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp)); 1571 1572 /* 1573 * Note: we no longer distinguish between VMIO and non-VMIO 1574 * buffers. 1575 */ 1576 1577 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); 1578 1579 /* 1580 * If we are defragging then we need a buffer with 1581 * b_kvasize != 0. XXX this situation should no longer 1582 * occur, if defrag is non-zero the buffer's b_kvasize 1583 * should also be non-zero at this point. XXX 1584 */ 1585 if (defrag && bp->b_kvasize == 0) { 1586 printf("Warning: defrag empty buffer %p\n", bp); 1587 continue; 1588 } 1589 1590 /* 1591 * Start freeing the bp. This is somewhat involved. nbp 1592 * remains valid only for QUEUE_EMPTY[KVA] bp's. 1593 */ 1594 1595 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) 1596 panic("getnewbuf: locked buf"); 1597 bremfree(bp); 1598 1599 if (qindex == QUEUE_CLEAN) { 1600 if (bp->b_flags & B_VMIO) { 1601 bp->b_flags &= ~B_ASYNC; 1602 vfs_vmio_release(bp); 1603 } 1604 if (bp->b_vp) 1605 brelvp(bp); 1606 } 1607 1608 /* 1609 * NOTE: nbp is now entirely invalid. We can only restart 1610 * the scan from this point on. 1611 * 1612 * Get the rest of the buffer freed up. b_kva* is still 1613 * valid after this operation. 1614 */ 1615 1616 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_deallocate) 1617 (*bioops.io_deallocate)(bp); 1618 if (bp->b_xflags & BX_BKGRDINPROG) 1619 panic("losing buffer 3"); 1620 LIST_REMOVE(bp, b_hash); 1621 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1622 1623 if (bp->b_bufsize) 1624 allocbuf(bp, 0); 1625 1626 bp->b_flags = 0; 1627 bp->b_xflags = 0; 1628 bp->b_dev = NODEV; 1629 bp->b_vp = NULL; 1630 bp->b_blkno = bp->b_lblkno = 0; 1631 bp->b_offset = NOOFFSET; 1632 bp->b_iodone = 0; 1633 bp->b_error = 0; 1634 bp->b_resid = 0; 1635 bp->b_bcount = 0; 1636 bp->b_npages = 0; 1637 bp->b_dirtyoff = bp->b_dirtyend = 0; 1638 1639 LIST_INIT(&bp->b_dep); 1640 1641 /* 1642 * If we are defragging then free the buffer. 1643 */ 1644 if (defrag) { 1645 bp->b_flags |= B_INVAL; 1646 bfreekva(bp); 1647 brelse(bp); 1648 defrag = 0; 1649 goto restart; 1650 } 1651 1652 /* 1653 * If we are overcomitted then recover the buffer and its 1654 * KVM space. This occurs in rare situations when multiple 1655 * processes are blocked in getnewbuf() or allocbuf(). 1656 */ 1657 if (bufspace >= hibufspace) 1658 flushingbufs = 1; 1659 if (flushingbufs && bp->b_kvasize != 0) { 1660 bp->b_flags |= B_INVAL; 1661 bfreekva(bp); 1662 brelse(bp); 1663 goto restart; 1664 } 1665 if (bufspace < lobufspace) 1666 flushingbufs = 0; 1667 break; 1668 } 1669 1670 /* 1671 * If we exhausted our list, sleep as appropriate. We may have to 1672 * wakeup various daemons and write out some dirty buffers. 1673 * 1674 * Generally we are sleeping due to insufficient buffer space. 1675 */ 1676 1677 if (bp == NULL) { 1678 int flags; 1679 char *waitmsg; 1680 1681 if (defrag) { 1682 flags = VFS_BIO_NEED_BUFSPACE; 1683 waitmsg = "nbufkv"; 1684 } else if (bufspace >= hibufspace) { 1685 waitmsg = "nbufbs"; 1686 flags = VFS_BIO_NEED_BUFSPACE; 1687 } else { 1688 waitmsg = "newbuf"; 1689 flags = VFS_BIO_NEED_ANY; 1690 } 1691 1692 bd_speedup(); /* heeeelp */ 1693 1694 needsbuffer |= flags; 1695 while (needsbuffer & flags) { 1696 if (tsleep(&needsbuffer, slpflag, waitmsg, slptimeo)) 1697 return (NULL); 1698 } 1699 } else { 1700 /* 1701 * We finally have a valid bp. We aren't quite out of the 1702 * woods, we still have to reserve kva space. In order 1703 * to keep fragmentation sane we only allocate kva in 1704 * BKVASIZE chunks. 1705 */ 1706 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 1707 1708 if (maxsize != bp->b_kvasize) { 1709 vm_offset_t addr = 0; 1710 1711 bfreekva(bp); 1712 1713 vm_map_lock(buffer_map); 1714 1715 if (vm_map_findspace(buffer_map, 1716 vm_map_min(buffer_map), maxsize, &addr)) { 1717 /* 1718 * Uh oh. Buffer map is to fragmented. We 1719 * must defragment the map. 1720 */ 1721 vm_map_unlock(buffer_map); 1722 ++bufdefragcnt; 1723 defrag = 1; 1724 bp->b_flags |= B_INVAL; 1725 brelse(bp); 1726 goto restart; 1727 } 1728 if (addr) { 1729 vm_map_insert(buffer_map, NULL, 0, 1730 addr, addr + maxsize, 1731 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT); 1732 1733 bp->b_kvabase = (caddr_t) addr; 1734 bp->b_kvasize = maxsize; 1735 bufspace += bp->b_kvasize; 1736 ++bufreusecnt; 1737 } 1738 vm_map_unlock(buffer_map); 1739 } 1740 bp->b_data = bp->b_kvabase; 1741 } 1742 return(bp); 1743 } 1744 1745 /* 1746 * buf_daemon: 1747 * 1748 * buffer flushing daemon. Buffers are normally flushed by the 1749 * update daemon but if it cannot keep up this process starts to 1750 * take the load in an attempt to prevent getnewbuf() from blocking. 1751 */ 1752 1753 static struct thread *bufdaemonthread; 1754 1755 static struct kproc_desc buf_kp = { 1756 "bufdaemon", 1757 buf_daemon, 1758 &bufdaemonthread 1759 }; 1760 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp) 1761 1762 static void 1763 buf_daemon() 1764 { 1765 int s; 1766 1767 /* 1768 * This process needs to be suspended prior to shutdown sync. 1769 */ 1770 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc, 1771 bufdaemonthread, SHUTDOWN_PRI_LAST); 1772 1773 /* 1774 * This process is allowed to take the buffer cache to the limit 1775 */ 1776 s = splbio(); 1777 1778 for (;;) { 1779 kproc_suspend_loop(); 1780 1781 /* 1782 * Do the flush. Limit the amount of in-transit I/O we 1783 * allow to build up, otherwise we would completely saturate 1784 * the I/O system. Wakeup any waiting processes before we 1785 * normally would so they can run in parallel with our drain. 1786 */ 1787 while (numdirtybuffers > lodirtybuffers) { 1788 if (flushbufqueues() == 0) 1789 break; 1790 waitrunningbufspace(); 1791 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 1792 } 1793 1794 /* 1795 * Only clear bd_request if we have reached our low water 1796 * mark. The buf_daemon normally waits 5 seconds and 1797 * then incrementally flushes any dirty buffers that have 1798 * built up, within reason. 1799 * 1800 * If we were unable to hit our low water mark and couldn't 1801 * find any flushable buffers, we sleep half a second. 1802 * Otherwise we loop immediately. 1803 */ 1804 if (numdirtybuffers <= lodirtybuffers) { 1805 /* 1806 * We reached our low water mark, reset the 1807 * request and sleep until we are needed again. 1808 * The sleep is just so the suspend code works. 1809 */ 1810 bd_request = 0; 1811 tsleep(&bd_request, 0, "psleep", hz); 1812 } else { 1813 /* 1814 * We couldn't find any flushable dirty buffers but 1815 * still have too many dirty buffers, we 1816 * have to sleep and try again. (rare) 1817 */ 1818 tsleep(&bd_request, 0, "qsleep", hz / 2); 1819 } 1820 } 1821 } 1822 1823 /* 1824 * flushbufqueues: 1825 * 1826 * Try to flush a buffer in the dirty queue. We must be careful to 1827 * free up B_INVAL buffers instead of write them, which NFS is 1828 * particularly sensitive to. 1829 */ 1830 1831 static int 1832 flushbufqueues(void) 1833 { 1834 struct buf *bp; 1835 int r = 0; 1836 1837 bp = TAILQ_FIRST(&bufqueues[QUEUE_DIRTY]); 1838 1839 while (bp) { 1840 KASSERT((bp->b_flags & B_DELWRI), ("unexpected clean buffer %p", bp)); 1841 if ((bp->b_flags & B_DELWRI) != 0 && 1842 (bp->b_xflags & BX_BKGRDINPROG) == 0) { 1843 if (bp->b_flags & B_INVAL) { 1844 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) 1845 panic("flushbufqueues: locked buf"); 1846 bremfree(bp); 1847 brelse(bp); 1848 ++r; 1849 break; 1850 } 1851 if (LIST_FIRST(&bp->b_dep) != NULL && 1852 bioops.io_countdeps && 1853 (bp->b_flags & B_DEFERRED) == 0 && 1854 (*bioops.io_countdeps)(bp, 0)) { 1855 TAILQ_REMOVE(&bufqueues[QUEUE_DIRTY], 1856 bp, b_freelist); 1857 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], 1858 bp, b_freelist); 1859 bp->b_flags |= B_DEFERRED; 1860 bp = TAILQ_FIRST(&bufqueues[QUEUE_DIRTY]); 1861 continue; 1862 } 1863 vfs_bio_awrite(bp); 1864 ++r; 1865 break; 1866 } 1867 bp = TAILQ_NEXT(bp, b_freelist); 1868 } 1869 return (r); 1870 } 1871 1872 /* 1873 * Check to see if a block is currently memory resident. 1874 */ 1875 struct buf * 1876 incore(struct vnode * vp, daddr_t blkno) 1877 { 1878 struct buf *bp; 1879 1880 int s = splbio(); 1881 bp = gbincore(vp, blkno); 1882 splx(s); 1883 return (bp); 1884 } 1885 1886 /* 1887 * Returns true if no I/O is needed to access the 1888 * associated VM object. This is like incore except 1889 * it also hunts around in the VM system for the data. 1890 */ 1891 1892 int 1893 inmem(struct vnode * vp, daddr_t blkno) 1894 { 1895 vm_object_t obj; 1896 vm_offset_t toff, tinc, size; 1897 vm_page_t m; 1898 vm_ooffset_t off; 1899 1900 if (incore(vp, blkno)) 1901 return 1; 1902 if (vp->v_mount == NULL) 1903 return 0; 1904 if (VOP_GETVOBJECT(vp, &obj) != 0 || (vp->v_flag & VOBJBUF) == 0) 1905 return 0; 1906 1907 size = PAGE_SIZE; 1908 if (size > vp->v_mount->mnt_stat.f_iosize) 1909 size = vp->v_mount->mnt_stat.f_iosize; 1910 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 1911 1912 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 1913 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 1914 if (!m) 1915 return 0; 1916 tinc = size; 1917 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 1918 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 1919 if (vm_page_is_valid(m, 1920 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 1921 return 0; 1922 } 1923 return 1; 1924 } 1925 1926 /* 1927 * vfs_setdirty: 1928 * 1929 * Sets the dirty range for a buffer based on the status of the dirty 1930 * bits in the pages comprising the buffer. 1931 * 1932 * The range is limited to the size of the buffer. 1933 * 1934 * This routine is primarily used by NFS, but is generalized for the 1935 * B_VMIO case. 1936 */ 1937 static void 1938 vfs_setdirty(struct buf *bp) 1939 { 1940 int i; 1941 vm_object_t object; 1942 1943 /* 1944 * Degenerate case - empty buffer 1945 */ 1946 1947 if (bp->b_bufsize == 0) 1948 return; 1949 1950 /* 1951 * We qualify the scan for modified pages on whether the 1952 * object has been flushed yet. The OBJ_WRITEABLE flag 1953 * is not cleared simply by protecting pages off. 1954 */ 1955 1956 if ((bp->b_flags & B_VMIO) == 0) 1957 return; 1958 1959 object = bp->b_pages[0]->object; 1960 1961 if ((object->flags & OBJ_WRITEABLE) && !(object->flags & OBJ_MIGHTBEDIRTY)) 1962 printf("Warning: object %p writeable but not mightbedirty\n", object); 1963 if (!(object->flags & OBJ_WRITEABLE) && (object->flags & OBJ_MIGHTBEDIRTY)) 1964 printf("Warning: object %p mightbedirty but not writeable\n", object); 1965 1966 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) { 1967 vm_offset_t boffset; 1968 vm_offset_t eoffset; 1969 1970 /* 1971 * test the pages to see if they have been modified directly 1972 * by users through the VM system. 1973 */ 1974 for (i = 0; i < bp->b_npages; i++) { 1975 vm_page_flag_clear(bp->b_pages[i], PG_ZERO); 1976 vm_page_test_dirty(bp->b_pages[i]); 1977 } 1978 1979 /* 1980 * Calculate the encompassing dirty range, boffset and eoffset, 1981 * (eoffset - boffset) bytes. 1982 */ 1983 1984 for (i = 0; i < bp->b_npages; i++) { 1985 if (bp->b_pages[i]->dirty) 1986 break; 1987 } 1988 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 1989 1990 for (i = bp->b_npages - 1; i >= 0; --i) { 1991 if (bp->b_pages[i]->dirty) { 1992 break; 1993 } 1994 } 1995 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 1996 1997 /* 1998 * Fit it to the buffer. 1999 */ 2000 2001 if (eoffset > bp->b_bcount) 2002 eoffset = bp->b_bcount; 2003 2004 /* 2005 * If we have a good dirty range, merge with the existing 2006 * dirty range. 2007 */ 2008 2009 if (boffset < eoffset) { 2010 if (bp->b_dirtyoff > boffset) 2011 bp->b_dirtyoff = boffset; 2012 if (bp->b_dirtyend < eoffset) 2013 bp->b_dirtyend = eoffset; 2014 } 2015 } 2016 } 2017 2018 /* 2019 * getblk: 2020 * 2021 * Get a block given a specified block and offset into a file/device. 2022 * The buffers B_DONE bit will be cleared on return, making it almost 2023 * ready for an I/O initiation. B_INVAL may or may not be set on 2024 * return. The caller should clear B_INVAL prior to initiating a 2025 * READ. 2026 * 2027 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2028 * an existing buffer. 2029 * 2030 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2031 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2032 * and then cleared based on the backing VM. If the previous buffer is 2033 * non-0-sized but invalid, B_CACHE will be cleared. 2034 * 2035 * If getblk() must create a new buffer, the new buffer is returned with 2036 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2037 * case it is returned with B_INVAL clear and B_CACHE set based on the 2038 * backing VM. 2039 * 2040 * getblk() also forces a VOP_BWRITE() for any B_DELWRI buffer whos 2041 * B_CACHE bit is clear. 2042 * 2043 * What this means, basically, is that the caller should use B_CACHE to 2044 * determine whether the buffer is fully valid or not and should clear 2045 * B_INVAL prior to issuing a read. If the caller intends to validate 2046 * the buffer by loading its data area with something, the caller needs 2047 * to clear B_INVAL. If the caller does this without issuing an I/O, 2048 * the caller should set B_CACHE ( as an optimization ), else the caller 2049 * should issue the I/O and biodone() will set B_CACHE if the I/O was 2050 * a write attempt or if it was a successfull read. If the caller 2051 * intends to issue a READ, the caller must clear B_INVAL and B_ERROR 2052 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 2053 */ 2054 struct buf * 2055 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo) 2056 { 2057 struct buf *bp; 2058 int s; 2059 struct bufhashhdr *bh; 2060 2061 if (size > MAXBSIZE) 2062 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 2063 2064 s = splbio(); 2065 loop: 2066 /* 2067 * Block if we are low on buffers. Certain processes are allowed 2068 * to completely exhaust the buffer cache. 2069 * 2070 * If this check ever becomes a bottleneck it may be better to 2071 * move it into the else, when gbincore() fails. At the moment 2072 * it isn't a problem. 2073 * 2074 * XXX remove, we cannot afford to block anywhere if holding a vnode 2075 * lock in low-memory situation, so take it to the max. 2076 */ 2077 if (numfreebuffers == 0) { 2078 if (!curproc) 2079 return NULL; 2080 needsbuffer |= VFS_BIO_NEED_ANY; 2081 tsleep(&needsbuffer, slpflag, "newbuf", slptimeo); 2082 } 2083 2084 if ((bp = gbincore(vp, blkno))) { 2085 /* 2086 * Buffer is in-core. If the buffer is not busy, it must 2087 * be on a queue. 2088 */ 2089 2090 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) { 2091 if (BUF_TIMELOCK(bp, LK_EXCLUSIVE | LK_SLEEPFAIL, 2092 "getblk", slpflag, slptimeo) == ENOLCK) 2093 goto loop; 2094 splx(s); 2095 return (struct buf *) NULL; 2096 } 2097 2098 /* 2099 * The buffer is locked. B_CACHE is cleared if the buffer is 2100 * invalid. Ohterwise, for a non-VMIO buffer, B_CACHE is set 2101 * and for a VMIO buffer B_CACHE is adjusted according to the 2102 * backing VM cache. 2103 */ 2104 if (bp->b_flags & B_INVAL) 2105 bp->b_flags &= ~B_CACHE; 2106 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 2107 bp->b_flags |= B_CACHE; 2108 bremfree(bp); 2109 2110 /* 2111 * check for size inconsistancies for non-VMIO case. 2112 */ 2113 2114 if (bp->b_bcount != size) { 2115 if ((bp->b_flags & B_VMIO) == 0 || 2116 (size > bp->b_kvasize)) { 2117 if (bp->b_flags & B_DELWRI) { 2118 bp->b_flags |= B_NOCACHE; 2119 VOP_BWRITE(bp->b_vp, bp); 2120 } else { 2121 if ((bp->b_flags & B_VMIO) && 2122 (LIST_FIRST(&bp->b_dep) == NULL)) { 2123 bp->b_flags |= B_RELBUF; 2124 brelse(bp); 2125 } else { 2126 bp->b_flags |= B_NOCACHE; 2127 VOP_BWRITE(bp->b_vp, bp); 2128 } 2129 } 2130 goto loop; 2131 } 2132 } 2133 2134 /* 2135 * If the size is inconsistant in the VMIO case, we can resize 2136 * the buffer. This might lead to B_CACHE getting set or 2137 * cleared. If the size has not changed, B_CACHE remains 2138 * unchanged from its previous state. 2139 */ 2140 2141 if (bp->b_bcount != size) 2142 allocbuf(bp, size); 2143 2144 KASSERT(bp->b_offset != NOOFFSET, 2145 ("getblk: no buffer offset")); 2146 2147 /* 2148 * A buffer with B_DELWRI set and B_CACHE clear must 2149 * be committed before we can return the buffer in 2150 * order to prevent the caller from issuing a read 2151 * ( due to B_CACHE not being set ) and overwriting 2152 * it. 2153 * 2154 * Most callers, including NFS and FFS, need this to 2155 * operate properly either because they assume they 2156 * can issue a read if B_CACHE is not set, or because 2157 * ( for example ) an uncached B_DELWRI might loop due 2158 * to softupdates re-dirtying the buffer. In the latter 2159 * case, B_CACHE is set after the first write completes, 2160 * preventing further loops. 2161 * 2162 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 2163 * above while extending the buffer, we cannot allow the 2164 * buffer to remain with B_CACHE set after the write 2165 * completes or it will represent a corrupt state. To 2166 * deal with this we set B_NOCACHE to scrap the buffer 2167 * after the write. 2168 * 2169 * We might be able to do something fancy, like setting 2170 * B_CACHE in bwrite() except if B_DELWRI is already set, 2171 * so the below call doesn't set B_CACHE, but that gets real 2172 * confusing. This is much easier. 2173 */ 2174 2175 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 2176 bp->b_flags |= B_NOCACHE; 2177 VOP_BWRITE(bp->b_vp, bp); 2178 goto loop; 2179 } 2180 2181 splx(s); 2182 bp->b_flags &= ~B_DONE; 2183 } else { 2184 /* 2185 * Buffer is not in-core, create new buffer. The buffer 2186 * returned by getnewbuf() is locked. Note that the returned 2187 * buffer is also considered valid (not marked B_INVAL). 2188 */ 2189 int bsize, maxsize, vmio; 2190 off_t offset; 2191 2192 if (vn_isdisk(vp, NULL)) 2193 bsize = DEV_BSIZE; 2194 else if (vp->v_mountedhere) 2195 bsize = vp->v_mountedhere->mnt_stat.f_iosize; 2196 else if (vp->v_mount) 2197 bsize = vp->v_mount->mnt_stat.f_iosize; 2198 else 2199 bsize = size; 2200 2201 offset = (off_t)blkno * bsize; 2202 vmio = (VOP_GETVOBJECT(vp, NULL) == 0) && (vp->v_flag & VOBJBUF); 2203 maxsize = vmio ? size + (offset & PAGE_MASK) : size; 2204 maxsize = imax(maxsize, bsize); 2205 2206 if ((bp = getnewbuf(slpflag, slptimeo, size, maxsize)) == NULL) { 2207 if (slpflag || slptimeo) { 2208 splx(s); 2209 return NULL; 2210 } 2211 goto loop; 2212 } 2213 2214 /* 2215 * This code is used to make sure that a buffer is not 2216 * created while the getnewbuf routine is blocked. 2217 * This can be a problem whether the vnode is locked or not. 2218 * If the buffer is created out from under us, we have to 2219 * throw away the one we just created. There is now window 2220 * race because we are safely running at splbio() from the 2221 * point of the duplicate buffer creation through to here, 2222 * and we've locked the buffer. 2223 */ 2224 if (gbincore(vp, blkno)) { 2225 bp->b_flags |= B_INVAL; 2226 brelse(bp); 2227 goto loop; 2228 } 2229 2230 /* 2231 * Insert the buffer into the hash, so that it can 2232 * be found by incore. 2233 */ 2234 bp->b_blkno = bp->b_lblkno = blkno; 2235 bp->b_offset = offset; 2236 2237 bgetvp(vp, bp); 2238 LIST_REMOVE(bp, b_hash); 2239 bh = bufhash(vp, blkno); 2240 LIST_INSERT_HEAD(bh, bp, b_hash); 2241 2242 /* 2243 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 2244 * buffer size starts out as 0, B_CACHE will be set by 2245 * allocbuf() for the VMIO case prior to it testing the 2246 * backing store for validity. 2247 */ 2248 2249 if (vmio) { 2250 bp->b_flags |= B_VMIO; 2251 #if defined(VFS_BIO_DEBUG) 2252 if (vp->v_type != VREG && vp->v_type != VBLK) 2253 printf("getblk: vmioing file type %d???\n", vp->v_type); 2254 #endif 2255 } else { 2256 bp->b_flags &= ~B_VMIO; 2257 } 2258 2259 allocbuf(bp, size); 2260 2261 splx(s); 2262 bp->b_flags &= ~B_DONE; 2263 } 2264 return (bp); 2265 } 2266 2267 /* 2268 * Get an empty, disassociated buffer of given size. The buffer is initially 2269 * set to B_INVAL. 2270 */ 2271 struct buf * 2272 geteblk(int size) 2273 { 2274 struct buf *bp; 2275 int s; 2276 int maxsize; 2277 2278 maxsize = (size + BKVAMASK) & ~BKVAMASK; 2279 2280 s = splbio(); 2281 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0); 2282 splx(s); 2283 allocbuf(bp, size); 2284 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 2285 return (bp); 2286 } 2287 2288 2289 /* 2290 * This code constitutes the buffer memory from either anonymous system 2291 * memory (in the case of non-VMIO operations) or from an associated 2292 * VM object (in the case of VMIO operations). This code is able to 2293 * resize a buffer up or down. 2294 * 2295 * Note that this code is tricky, and has many complications to resolve 2296 * deadlock or inconsistant data situations. Tread lightly!!! 2297 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 2298 * the caller. Calling this code willy nilly can result in the loss of data. 2299 * 2300 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 2301 * B_CACHE for the non-VMIO case. 2302 */ 2303 2304 int 2305 allocbuf(struct buf *bp, int size) 2306 { 2307 int newbsize, mbsize; 2308 int i; 2309 2310 if (BUF_REFCNT(bp) == 0) 2311 panic("allocbuf: buffer not busy"); 2312 2313 if (bp->b_kvasize < size) 2314 panic("allocbuf: buffer too small"); 2315 2316 if ((bp->b_flags & B_VMIO) == 0) { 2317 caddr_t origbuf; 2318 int origbufsize; 2319 /* 2320 * Just get anonymous memory from the kernel. Don't 2321 * mess with B_CACHE. 2322 */ 2323 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2324 #if !defined(NO_B_MALLOC) 2325 if (bp->b_flags & B_MALLOC) 2326 newbsize = mbsize; 2327 else 2328 #endif 2329 newbsize = round_page(size); 2330 2331 if (newbsize < bp->b_bufsize) { 2332 #if !defined(NO_B_MALLOC) 2333 /* 2334 * malloced buffers are not shrunk 2335 */ 2336 if (bp->b_flags & B_MALLOC) { 2337 if (newbsize) { 2338 bp->b_bcount = size; 2339 } else { 2340 free(bp->b_data, M_BIOBUF); 2341 if (bp->b_bufsize) { 2342 bufmallocspace -= bp->b_bufsize; 2343 bufspacewakeup(); 2344 bp->b_bufsize = 0; 2345 } 2346 bp->b_data = bp->b_kvabase; 2347 bp->b_bcount = 0; 2348 bp->b_flags &= ~B_MALLOC; 2349 } 2350 return 1; 2351 } 2352 #endif 2353 vm_hold_free_pages( 2354 bp, 2355 (vm_offset_t) bp->b_data + newbsize, 2356 (vm_offset_t) bp->b_data + bp->b_bufsize); 2357 } else if (newbsize > bp->b_bufsize) { 2358 #if !defined(NO_B_MALLOC) 2359 /* 2360 * We only use malloced memory on the first allocation. 2361 * and revert to page-allocated memory when the buffer 2362 * grows. 2363 */ 2364 if ( (bufmallocspace < maxbufmallocspace) && 2365 (bp->b_bufsize == 0) && 2366 (mbsize <= PAGE_SIZE/2)) { 2367 2368 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 2369 bp->b_bufsize = mbsize; 2370 bp->b_bcount = size; 2371 bp->b_flags |= B_MALLOC; 2372 bufmallocspace += mbsize; 2373 return 1; 2374 } 2375 #endif 2376 origbuf = NULL; 2377 origbufsize = 0; 2378 #if !defined(NO_B_MALLOC) 2379 /* 2380 * If the buffer is growing on its other-than-first allocation, 2381 * then we revert to the page-allocation scheme. 2382 */ 2383 if (bp->b_flags & B_MALLOC) { 2384 origbuf = bp->b_data; 2385 origbufsize = bp->b_bufsize; 2386 bp->b_data = bp->b_kvabase; 2387 if (bp->b_bufsize) { 2388 bufmallocspace -= bp->b_bufsize; 2389 bufspacewakeup(); 2390 bp->b_bufsize = 0; 2391 } 2392 bp->b_flags &= ~B_MALLOC; 2393 newbsize = round_page(newbsize); 2394 } 2395 #endif 2396 vm_hold_load_pages( 2397 bp, 2398 (vm_offset_t) bp->b_data + bp->b_bufsize, 2399 (vm_offset_t) bp->b_data + newbsize); 2400 #if !defined(NO_B_MALLOC) 2401 if (origbuf) { 2402 bcopy(origbuf, bp->b_data, origbufsize); 2403 free(origbuf, M_BIOBUF); 2404 } 2405 #endif 2406 } 2407 } else { 2408 vm_page_t m; 2409 int desiredpages; 2410 2411 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2412 desiredpages = (size == 0) ? 0 : 2413 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 2414 2415 #if !defined(NO_B_MALLOC) 2416 if (bp->b_flags & B_MALLOC) 2417 panic("allocbuf: VMIO buffer can't be malloced"); 2418 #endif 2419 /* 2420 * Set B_CACHE initially if buffer is 0 length or will become 2421 * 0-length. 2422 */ 2423 if (size == 0 || bp->b_bufsize == 0) 2424 bp->b_flags |= B_CACHE; 2425 2426 if (newbsize < bp->b_bufsize) { 2427 /* 2428 * DEV_BSIZE aligned new buffer size is less then the 2429 * DEV_BSIZE aligned existing buffer size. Figure out 2430 * if we have to remove any pages. 2431 */ 2432 if (desiredpages < bp->b_npages) { 2433 for (i = desiredpages; i < bp->b_npages; i++) { 2434 /* 2435 * the page is not freed here -- it 2436 * is the responsibility of 2437 * vnode_pager_setsize 2438 */ 2439 m = bp->b_pages[i]; 2440 KASSERT(m != bogus_page, 2441 ("allocbuf: bogus page found")); 2442 while (vm_page_sleep_busy(m, TRUE, "biodep")) 2443 ; 2444 2445 bp->b_pages[i] = NULL; 2446 vm_page_unwire(m, 0); 2447 } 2448 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) + 2449 (desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages)); 2450 bp->b_npages = desiredpages; 2451 } 2452 } else if (size > bp->b_bcount) { 2453 /* 2454 * We are growing the buffer, possibly in a 2455 * byte-granular fashion. 2456 */ 2457 struct vnode *vp; 2458 vm_object_t obj; 2459 vm_offset_t toff; 2460 vm_offset_t tinc; 2461 2462 /* 2463 * Step 1, bring in the VM pages from the object, 2464 * allocating them if necessary. We must clear 2465 * B_CACHE if these pages are not valid for the 2466 * range covered by the buffer. 2467 */ 2468 2469 vp = bp->b_vp; 2470 VOP_GETVOBJECT(vp, &obj); 2471 2472 while (bp->b_npages < desiredpages) { 2473 vm_page_t m; 2474 vm_pindex_t pi; 2475 2476 pi = OFF_TO_IDX(bp->b_offset) + bp->b_npages; 2477 if ((m = vm_page_lookup(obj, pi)) == NULL) { 2478 /* 2479 * note: must allocate system pages 2480 * since blocking here could intefere 2481 * with paging I/O, no matter which 2482 * process we are. 2483 */ 2484 m = vm_page_alloc(obj, pi, VM_ALLOC_SYSTEM); 2485 if (m == NULL) { 2486 VM_WAIT; 2487 vm_pageout_deficit += desiredpages - bp->b_npages; 2488 } else { 2489 vm_page_wire(m); 2490 vm_page_wakeup(m); 2491 bp->b_flags &= ~B_CACHE; 2492 bp->b_pages[bp->b_npages] = m; 2493 ++bp->b_npages; 2494 } 2495 continue; 2496 } 2497 2498 /* 2499 * We found a page. If we have to sleep on it, 2500 * retry because it might have gotten freed out 2501 * from under us. 2502 * 2503 * We can only test PG_BUSY here. Blocking on 2504 * m->busy might lead to a deadlock: 2505 * 2506 * vm_fault->getpages->cluster_read->allocbuf 2507 * 2508 */ 2509 2510 if (vm_page_sleep_busy(m, FALSE, "pgtblk")) 2511 continue; 2512 2513 /* 2514 * We have a good page. Should we wakeup the 2515 * page daemon? 2516 */ 2517 if ((curthread != pagethread) && 2518 ((m->queue - m->pc) == PQ_CACHE) && 2519 ((vmstats.v_free_count + vmstats.v_cache_count) < 2520 (vmstats.v_free_min + vmstats.v_cache_min))) { 2521 pagedaemon_wakeup(); 2522 } 2523 vm_page_flag_clear(m, PG_ZERO); 2524 vm_page_wire(m); 2525 bp->b_pages[bp->b_npages] = m; 2526 ++bp->b_npages; 2527 } 2528 2529 /* 2530 * Step 2. We've loaded the pages into the buffer, 2531 * we have to figure out if we can still have B_CACHE 2532 * set. Note that B_CACHE is set according to the 2533 * byte-granular range ( bcount and size ), new the 2534 * aligned range ( newbsize ). 2535 * 2536 * The VM test is against m->valid, which is DEV_BSIZE 2537 * aligned. Needless to say, the validity of the data 2538 * needs to also be DEV_BSIZE aligned. Note that this 2539 * fails with NFS if the server or some other client 2540 * extends the file's EOF. If our buffer is resized, 2541 * B_CACHE may remain set! XXX 2542 */ 2543 2544 toff = bp->b_bcount; 2545 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 2546 2547 while ((bp->b_flags & B_CACHE) && toff < size) { 2548 vm_pindex_t pi; 2549 2550 if (tinc > (size - toff)) 2551 tinc = size - toff; 2552 2553 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 2554 PAGE_SHIFT; 2555 2556 vfs_buf_test_cache( 2557 bp, 2558 bp->b_offset, 2559 toff, 2560 tinc, 2561 bp->b_pages[pi] 2562 ); 2563 toff += tinc; 2564 tinc = PAGE_SIZE; 2565 } 2566 2567 /* 2568 * Step 3, fixup the KVM pmap. Remember that 2569 * bp->b_data is relative to bp->b_offset, but 2570 * bp->b_offset may be offset into the first page. 2571 */ 2572 2573 bp->b_data = (caddr_t) 2574 trunc_page((vm_offset_t)bp->b_data); 2575 pmap_qenter( 2576 (vm_offset_t)bp->b_data, 2577 bp->b_pages, 2578 bp->b_npages 2579 ); 2580 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 2581 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 2582 } 2583 } 2584 if (newbsize < bp->b_bufsize) 2585 bufspacewakeup(); 2586 bp->b_bufsize = newbsize; /* actual buffer allocation */ 2587 bp->b_bcount = size; /* requested buffer size */ 2588 return 1; 2589 } 2590 2591 /* 2592 * biowait: 2593 * 2594 * Wait for buffer I/O completion, returning error status. The buffer 2595 * is left locked and B_DONE on return. B_EINTR is converted into a EINTR 2596 * error and cleared. 2597 */ 2598 int 2599 biowait(struct buf * bp) 2600 { 2601 int s; 2602 2603 s = splbio(); 2604 while ((bp->b_flags & B_DONE) == 0) { 2605 #if defined(NO_SCHEDULE_MODS) 2606 tsleep(bp, 0, "biowait", 0); 2607 #else 2608 if (bp->b_flags & B_READ) 2609 tsleep(bp, 0, "biord", 0); 2610 else 2611 tsleep(bp, 0, "biowr", 0); 2612 #endif 2613 } 2614 splx(s); 2615 if (bp->b_flags & B_EINTR) { 2616 bp->b_flags &= ~B_EINTR; 2617 return (EINTR); 2618 } 2619 if (bp->b_flags & B_ERROR) { 2620 return (bp->b_error ? bp->b_error : EIO); 2621 } else { 2622 return (0); 2623 } 2624 } 2625 2626 /* 2627 * biodone: 2628 * 2629 * Finish I/O on a buffer, optionally calling a completion function. 2630 * This is usually called from an interrupt so process blocking is 2631 * not allowed. 2632 * 2633 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 2634 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 2635 * assuming B_INVAL is clear. 2636 * 2637 * For the VMIO case, we set B_CACHE if the op was a read and no 2638 * read error occured, or if the op was a write. B_CACHE is never 2639 * set if the buffer is invalid or otherwise uncacheable. 2640 * 2641 * biodone does not mess with B_INVAL, allowing the I/O routine or the 2642 * initiator to leave B_INVAL set to brelse the buffer out of existance 2643 * in the biodone routine. 2644 */ 2645 void 2646 biodone(struct buf * bp) 2647 { 2648 int s, error; 2649 2650 s = splbio(); 2651 2652 KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp, BUF_REFCNT(bp))); 2653 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 2654 2655 bp->b_flags |= B_DONE; 2656 runningbufwakeup(bp); 2657 2658 if (bp->b_flags & B_FREEBUF) { 2659 brelse(bp); 2660 splx(s); 2661 return; 2662 } 2663 2664 if ((bp->b_flags & B_READ) == 0) { 2665 vwakeup(bp); 2666 } 2667 2668 /* call optional completion function if requested */ 2669 if (bp->b_flags & B_CALL) { 2670 bp->b_flags &= ~B_CALL; 2671 (*bp->b_iodone) (bp); 2672 splx(s); 2673 return; 2674 } 2675 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_complete) 2676 (*bioops.io_complete)(bp); 2677 2678 if (bp->b_flags & B_VMIO) { 2679 int i; 2680 vm_ooffset_t foff; 2681 vm_page_t m; 2682 vm_object_t obj; 2683 int iosize; 2684 struct vnode *vp = bp->b_vp; 2685 2686 error = VOP_GETVOBJECT(vp, &obj); 2687 2688 #if defined(VFS_BIO_DEBUG) 2689 if (vp->v_usecount == 0) { 2690 panic("biodone: zero vnode ref count"); 2691 } 2692 2693 if (error) { 2694 panic("biodone: missing VM object"); 2695 } 2696 2697 if ((vp->v_flag & VOBJBUF) == 0) { 2698 panic("biodone: vnode is not setup for merged cache"); 2699 } 2700 #endif 2701 2702 foff = bp->b_offset; 2703 KASSERT(bp->b_offset != NOOFFSET, 2704 ("biodone: no buffer offset")); 2705 2706 if (error) { 2707 panic("biodone: no object"); 2708 } 2709 #if defined(VFS_BIO_DEBUG) 2710 if (obj->paging_in_progress < bp->b_npages) { 2711 printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n", 2712 obj->paging_in_progress, bp->b_npages); 2713 } 2714 #endif 2715 2716 /* 2717 * Set B_CACHE if the op was a normal read and no error 2718 * occured. B_CACHE is set for writes in the b*write() 2719 * routines. 2720 */ 2721 iosize = bp->b_bcount - bp->b_resid; 2722 if ((bp->b_flags & (B_READ|B_FREEBUF|B_INVAL|B_NOCACHE|B_ERROR)) == B_READ) { 2723 bp->b_flags |= B_CACHE; 2724 } 2725 2726 for (i = 0; i < bp->b_npages; i++) { 2727 int bogusflag = 0; 2728 int resid; 2729 2730 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 2731 if (resid > iosize) 2732 resid = iosize; 2733 2734 /* 2735 * cleanup bogus pages, restoring the originals 2736 */ 2737 m = bp->b_pages[i]; 2738 if (m == bogus_page) { 2739 bogusflag = 1; 2740 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 2741 if (m == NULL) 2742 panic("biodone: page disappeared"); 2743 bp->b_pages[i] = m; 2744 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 2745 } 2746 #if defined(VFS_BIO_DEBUG) 2747 if (OFF_TO_IDX(foff) != m->pindex) { 2748 printf( 2749 "biodone: foff(%lu)/m->pindex(%d) mismatch\n", 2750 (unsigned long)foff, m->pindex); 2751 } 2752 #endif 2753 2754 /* 2755 * In the write case, the valid and clean bits are 2756 * already changed correctly ( see bdwrite() ), so we 2757 * only need to do this here in the read case. 2758 */ 2759 if ((bp->b_flags & B_READ) && !bogusflag && resid > 0) { 2760 vfs_page_set_valid(bp, foff, i, m); 2761 } 2762 vm_page_flag_clear(m, PG_ZERO); 2763 2764 /* 2765 * when debugging new filesystems or buffer I/O methods, this 2766 * is the most common error that pops up. if you see this, you 2767 * have not set the page busy flag correctly!!! 2768 */ 2769 if (m->busy == 0) { 2770 printf("biodone: page busy < 0, " 2771 "pindex: %d, foff: 0x(%x,%x), " 2772 "resid: %d, index: %d\n", 2773 (int) m->pindex, (int)(foff >> 32), 2774 (int) foff & 0xffffffff, resid, i); 2775 if (!vn_isdisk(vp, NULL)) 2776 printf(" iosize: %ld, lblkno: %d, flags: 0x%lx, npages: %d\n", 2777 bp->b_vp->v_mount->mnt_stat.f_iosize, 2778 (int) bp->b_lblkno, 2779 bp->b_flags, bp->b_npages); 2780 else 2781 printf(" VDEV, lblkno: %d, flags: 0x%lx, npages: %d\n", 2782 (int) bp->b_lblkno, 2783 bp->b_flags, bp->b_npages); 2784 printf(" valid: 0x%x, dirty: 0x%x, wired: %d\n", 2785 m->valid, m->dirty, m->wire_count); 2786 panic("biodone: page busy < 0\n"); 2787 } 2788 vm_page_io_finish(m); 2789 vm_object_pip_subtract(obj, 1); 2790 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2791 iosize -= resid; 2792 } 2793 if (obj) 2794 vm_object_pip_wakeupn(obj, 0); 2795 } 2796 2797 /* 2798 * For asynchronous completions, release the buffer now. The brelse 2799 * will do a wakeup there if necessary - so no need to do a wakeup 2800 * here in the async case. The sync case always needs to do a wakeup. 2801 */ 2802 2803 if (bp->b_flags & B_ASYNC) { 2804 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR | B_RELBUF)) != 0) 2805 brelse(bp); 2806 else 2807 bqrelse(bp); 2808 } else { 2809 wakeup(bp); 2810 } 2811 splx(s); 2812 } 2813 2814 /* 2815 * This routine is called in lieu of iodone in the case of 2816 * incomplete I/O. This keeps the busy status for pages 2817 * consistant. 2818 */ 2819 void 2820 vfs_unbusy_pages(struct buf * bp) 2821 { 2822 int i; 2823 2824 runningbufwakeup(bp); 2825 if (bp->b_flags & B_VMIO) { 2826 struct vnode *vp = bp->b_vp; 2827 vm_object_t obj; 2828 2829 VOP_GETVOBJECT(vp, &obj); 2830 2831 for (i = 0; i < bp->b_npages; i++) { 2832 vm_page_t m = bp->b_pages[i]; 2833 2834 if (m == bogus_page) { 2835 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 2836 if (!m) { 2837 panic("vfs_unbusy_pages: page missing\n"); 2838 } 2839 bp->b_pages[i] = m; 2840 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 2841 } 2842 vm_object_pip_subtract(obj, 1); 2843 vm_page_flag_clear(m, PG_ZERO); 2844 vm_page_io_finish(m); 2845 } 2846 vm_object_pip_wakeupn(obj, 0); 2847 } 2848 } 2849 2850 /* 2851 * vfs_page_set_valid: 2852 * 2853 * Set the valid bits in a page based on the supplied offset. The 2854 * range is restricted to the buffer's size. 2855 * 2856 * This routine is typically called after a read completes. 2857 */ 2858 static void 2859 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m) 2860 { 2861 vm_ooffset_t soff, eoff; 2862 2863 /* 2864 * Start and end offsets in buffer. eoff - soff may not cross a 2865 * page boundry or cross the end of the buffer. The end of the 2866 * buffer, in this case, is our file EOF, not the allocation size 2867 * of the buffer. 2868 */ 2869 soff = off; 2870 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2871 if (eoff > bp->b_offset + bp->b_bcount) 2872 eoff = bp->b_offset + bp->b_bcount; 2873 2874 /* 2875 * Set valid range. This is typically the entire buffer and thus the 2876 * entire page. 2877 */ 2878 if (eoff > soff) { 2879 vm_page_set_validclean( 2880 m, 2881 (vm_offset_t) (soff & PAGE_MASK), 2882 (vm_offset_t) (eoff - soff) 2883 ); 2884 } 2885 } 2886 2887 /* 2888 * This routine is called before a device strategy routine. 2889 * It is used to tell the VM system that paging I/O is in 2890 * progress, and treat the pages associated with the buffer 2891 * almost as being PG_BUSY. Also the object paging_in_progress 2892 * flag is handled to make sure that the object doesn't become 2893 * inconsistant. 2894 * 2895 * Since I/O has not been initiated yet, certain buffer flags 2896 * such as B_ERROR or B_INVAL may be in an inconsistant state 2897 * and should be ignored. 2898 */ 2899 void 2900 vfs_busy_pages(struct buf * bp, int clear_modify) 2901 { 2902 int i, bogus; 2903 2904 if (bp->b_flags & B_VMIO) { 2905 struct vnode *vp = bp->b_vp; 2906 vm_object_t obj; 2907 vm_ooffset_t foff; 2908 2909 VOP_GETVOBJECT(vp, &obj); 2910 foff = bp->b_offset; 2911 KASSERT(bp->b_offset != NOOFFSET, 2912 ("vfs_busy_pages: no buffer offset")); 2913 vfs_setdirty(bp); 2914 2915 retry: 2916 for (i = 0; i < bp->b_npages; i++) { 2917 vm_page_t m = bp->b_pages[i]; 2918 if (vm_page_sleep_busy(m, FALSE, "vbpage")) 2919 goto retry; 2920 } 2921 2922 bogus = 0; 2923 for (i = 0; i < bp->b_npages; i++) { 2924 vm_page_t m = bp->b_pages[i]; 2925 2926 vm_page_flag_clear(m, PG_ZERO); 2927 if ((bp->b_flags & B_CLUSTER) == 0) { 2928 vm_object_pip_add(obj, 1); 2929 vm_page_io_start(m); 2930 } 2931 2932 /* 2933 * When readying a buffer for a read ( i.e 2934 * clear_modify == 0 ), it is important to do 2935 * bogus_page replacement for valid pages in 2936 * partially instantiated buffers. Partially 2937 * instantiated buffers can, in turn, occur when 2938 * reconstituting a buffer from its VM backing store 2939 * base. We only have to do this if B_CACHE is 2940 * clear ( which causes the I/O to occur in the 2941 * first place ). The replacement prevents the read 2942 * I/O from overwriting potentially dirty VM-backed 2943 * pages. XXX bogus page replacement is, uh, bogus. 2944 * It may not work properly with small-block devices. 2945 * We need to find a better way. 2946 */ 2947 2948 vm_page_protect(m, VM_PROT_NONE); 2949 if (clear_modify) 2950 vfs_page_set_valid(bp, foff, i, m); 2951 else if (m->valid == VM_PAGE_BITS_ALL && 2952 (bp->b_flags & B_CACHE) == 0) { 2953 bp->b_pages[i] = bogus_page; 2954 bogus++; 2955 } 2956 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2957 } 2958 if (bogus) 2959 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 2960 } 2961 2962 /* 2963 * This is the easiest place to put the process accounting for the I/O 2964 * for now. 2965 */ 2966 { 2967 struct proc *p; 2968 2969 if ((p = curthread->td_proc) != NULL) { 2970 if (bp->b_flags & B_READ) 2971 p->p_stats->p_ru.ru_inblock++; 2972 else 2973 p->p_stats->p_ru.ru_oublock++; 2974 } 2975 } 2976 } 2977 2978 /* 2979 * Tell the VM system that the pages associated with this buffer 2980 * are clean. This is used for delayed writes where the data is 2981 * going to go to disk eventually without additional VM intevention. 2982 * 2983 * Note that while we only really need to clean through to b_bcount, we 2984 * just go ahead and clean through to b_bufsize. 2985 */ 2986 static void 2987 vfs_clean_pages(struct buf * bp) 2988 { 2989 int i; 2990 2991 if (bp->b_flags & B_VMIO) { 2992 vm_ooffset_t foff; 2993 2994 foff = bp->b_offset; 2995 KASSERT(bp->b_offset != NOOFFSET, 2996 ("vfs_clean_pages: no buffer offset")); 2997 for (i = 0; i < bp->b_npages; i++) { 2998 vm_page_t m = bp->b_pages[i]; 2999 vm_ooffset_t noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3000 vm_ooffset_t eoff = noff; 3001 3002 if (eoff > bp->b_offset + bp->b_bufsize) 3003 eoff = bp->b_offset + bp->b_bufsize; 3004 vfs_page_set_valid(bp, foff, i, m); 3005 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3006 foff = noff; 3007 } 3008 } 3009 } 3010 3011 /* 3012 * vfs_bio_set_validclean: 3013 * 3014 * Set the range within the buffer to valid and clean. The range is 3015 * relative to the beginning of the buffer, b_offset. Note that b_offset 3016 * itself may be offset from the beginning of the first page. 3017 */ 3018 3019 void 3020 vfs_bio_set_validclean(struct buf *bp, int base, int size) 3021 { 3022 if (bp->b_flags & B_VMIO) { 3023 int i; 3024 int n; 3025 3026 /* 3027 * Fixup base to be relative to beginning of first page. 3028 * Set initial n to be the maximum number of bytes in the 3029 * first page that can be validated. 3030 */ 3031 3032 base += (bp->b_offset & PAGE_MASK); 3033 n = PAGE_SIZE - (base & PAGE_MASK); 3034 3035 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 3036 vm_page_t m = bp->b_pages[i]; 3037 3038 if (n > size) 3039 n = size; 3040 3041 vm_page_set_validclean(m, base & PAGE_MASK, n); 3042 base += n; 3043 size -= n; 3044 n = PAGE_SIZE; 3045 } 3046 } 3047 } 3048 3049 /* 3050 * vfs_bio_clrbuf: 3051 * 3052 * clear a buffer. This routine essentially fakes an I/O, so we need 3053 * to clear B_ERROR and B_INVAL. 3054 * 3055 * Note that while we only theoretically need to clear through b_bcount, 3056 * we go ahead and clear through b_bufsize. 3057 */ 3058 3059 void 3060 vfs_bio_clrbuf(struct buf *bp) 3061 { 3062 int i, mask = 0; 3063 caddr_t sa, ea; 3064 if ((bp->b_flags & (B_VMIO | B_MALLOC)) == B_VMIO) { 3065 bp->b_flags &= ~(B_INVAL|B_ERROR); 3066 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 3067 (bp->b_offset & PAGE_MASK) == 0) { 3068 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 3069 if ((bp->b_pages[0]->valid & mask) == mask) { 3070 bp->b_resid = 0; 3071 return; 3072 } 3073 if (((bp->b_pages[0]->flags & PG_ZERO) == 0) && 3074 ((bp->b_pages[0]->valid & mask) == 0)) { 3075 bzero(bp->b_data, bp->b_bufsize); 3076 bp->b_pages[0]->valid |= mask; 3077 bp->b_resid = 0; 3078 return; 3079 } 3080 } 3081 ea = sa = bp->b_data; 3082 for(i=0;i<bp->b_npages;i++,sa=ea) { 3083 int j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; 3084 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); 3085 ea = (caddr_t)(vm_offset_t)ulmin( 3086 (u_long)(vm_offset_t)ea, 3087 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); 3088 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 3089 if ((bp->b_pages[i]->valid & mask) == mask) 3090 continue; 3091 if ((bp->b_pages[i]->valid & mask) == 0) { 3092 if ((bp->b_pages[i]->flags & PG_ZERO) == 0) { 3093 bzero(sa, ea - sa); 3094 } 3095 } else { 3096 for (; sa < ea; sa += DEV_BSIZE, j++) { 3097 if (((bp->b_pages[i]->flags & PG_ZERO) == 0) && 3098 (bp->b_pages[i]->valid & (1<<j)) == 0) 3099 bzero(sa, DEV_BSIZE); 3100 } 3101 } 3102 bp->b_pages[i]->valid |= mask; 3103 vm_page_flag_clear(bp->b_pages[i], PG_ZERO); 3104 } 3105 bp->b_resid = 0; 3106 } else { 3107 clrbuf(bp); 3108 } 3109 } 3110 3111 /* 3112 * vm_hold_load_pages and vm_hold_unload pages get pages into 3113 * a buffers address space. The pages are anonymous and are 3114 * not associated with a file object. 3115 */ 3116 void 3117 vm_hold_load_pages(struct buf * bp, vm_offset_t from, vm_offset_t to) 3118 { 3119 vm_offset_t pg; 3120 vm_page_t p; 3121 int index; 3122 3123 to = round_page(to); 3124 from = round_page(from); 3125 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3126 3127 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3128 3129 tryagain: 3130 3131 /* 3132 * note: must allocate system pages since blocking here 3133 * could intefere with paging I/O, no matter which 3134 * process we are. 3135 */ 3136 p = vm_page_alloc(kernel_object, 3137 ((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 3138 VM_ALLOC_SYSTEM); 3139 if (!p) { 3140 vm_pageout_deficit += (to - from) >> PAGE_SHIFT; 3141 VM_WAIT; 3142 goto tryagain; 3143 } 3144 vm_page_wire(p); 3145 p->valid = VM_PAGE_BITS_ALL; 3146 vm_page_flag_clear(p, PG_ZERO); 3147 pmap_kenter(pg, VM_PAGE_TO_PHYS(p)); 3148 bp->b_pages[index] = p; 3149 vm_page_wakeup(p); 3150 } 3151 bp->b_npages = index; 3152 } 3153 3154 void 3155 vm_hold_free_pages(struct buf * bp, vm_offset_t from, vm_offset_t to) 3156 { 3157 vm_offset_t pg; 3158 vm_page_t p; 3159 int index, newnpages; 3160 3161 from = round_page(from); 3162 to = round_page(to); 3163 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3164 3165 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3166 p = bp->b_pages[index]; 3167 if (p && (index < bp->b_npages)) { 3168 if (p->busy) { 3169 printf("vm_hold_free_pages: blkno: %d, lblkno: %d\n", 3170 bp->b_blkno, bp->b_lblkno); 3171 } 3172 bp->b_pages[index] = NULL; 3173 pmap_kremove(pg); 3174 vm_page_busy(p); 3175 vm_page_unwire(p, 0); 3176 vm_page_free(p); 3177 } 3178 } 3179 bp->b_npages = newnpages; 3180 } 3181 3182 /* 3183 * Map an IO request into kernel virtual address space. 3184 * 3185 * All requests are (re)mapped into kernel VA space. 3186 * Notice that we use b_bufsize for the size of the buffer 3187 * to be mapped. b_bcount might be modified by the driver. 3188 */ 3189 int 3190 vmapbuf(struct buf *bp) 3191 { 3192 caddr_t addr, v, kva; 3193 vm_offset_t pa; 3194 int pidx; 3195 int i; 3196 struct vm_page *m; 3197 3198 if ((bp->b_flags & B_PHYS) == 0) 3199 panic("vmapbuf"); 3200 if (bp->b_bufsize < 0) 3201 return (-1); 3202 for (v = bp->b_saveaddr, 3203 addr = (caddr_t)trunc_page((vm_offset_t)bp->b_data), 3204 pidx = 0; 3205 addr < bp->b_data + bp->b_bufsize; 3206 addr += PAGE_SIZE, v += PAGE_SIZE, pidx++) { 3207 /* 3208 * Do the vm_fault if needed; do the copy-on-write thing 3209 * when reading stuff off device into memory. 3210 */ 3211 retry: 3212 i = vm_fault_quick((addr >= bp->b_data) ? addr : bp->b_data, 3213 (bp->b_flags&B_READ)?(VM_PROT_READ|VM_PROT_WRITE):VM_PROT_READ); 3214 if (i < 0) { 3215 for (i = 0; i < pidx; ++i) { 3216 vm_page_unhold(bp->b_pages[i]); 3217 bp->b_pages[i] = NULL; 3218 } 3219 return(-1); 3220 } 3221 3222 /* 3223 * WARNING! If sparc support is MFCd in the future this will 3224 * have to be changed from pmap_kextract() to pmap_extract() 3225 * ala -current. 3226 */ 3227 #ifdef __sparc64__ 3228 #error "If MFCing sparc support use pmap_extract" 3229 #endif 3230 pa = pmap_kextract((vm_offset_t)addr); 3231 if (pa == 0) { 3232 printf("vmapbuf: warning, race against user address during I/O"); 3233 goto retry; 3234 } 3235 m = PHYS_TO_VM_PAGE(pa); 3236 vm_page_hold(m); 3237 bp->b_pages[pidx] = m; 3238 } 3239 if (pidx > btoc(MAXPHYS)) 3240 panic("vmapbuf: mapped more than MAXPHYS"); 3241 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx); 3242 3243 kva = bp->b_saveaddr; 3244 bp->b_npages = pidx; 3245 bp->b_saveaddr = bp->b_data; 3246 bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK); 3247 return(0); 3248 } 3249 3250 /* 3251 * Free the io map PTEs associated with this IO operation. 3252 * We also invalidate the TLB entries and restore the original b_addr. 3253 */ 3254 void 3255 vunmapbuf(bp) 3256 struct buf *bp; 3257 { 3258 int pidx; 3259 int npages; 3260 vm_page_t *m; 3261 3262 if ((bp->b_flags & B_PHYS) == 0) 3263 panic("vunmapbuf"); 3264 3265 npages = bp->b_npages; 3266 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), 3267 npages); 3268 m = bp->b_pages; 3269 for (pidx = 0; pidx < npages; pidx++) 3270 vm_page_unhold(*m++); 3271 3272 bp->b_data = bp->b_saveaddr; 3273 } 3274 3275 #include "opt_ddb.h" 3276 #ifdef DDB 3277 #include <ddb/ddb.h> 3278 3279 DB_SHOW_COMMAND(buffer, db_show_buffer) 3280 { 3281 /* get args */ 3282 struct buf *bp = (struct buf *)addr; 3283 3284 if (!have_addr) { 3285 db_printf("usage: show buffer <addr>\n"); 3286 return; 3287 } 3288 3289 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS); 3290 db_printf("b_error = %d, b_bufsize = %ld, b_bcount = %ld, " 3291 "b_resid = %ld\nb_dev = (%d,%d), b_data = %p, " 3292 "b_blkno = %d, b_pblkno = %d\n", 3293 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 3294 major(bp->b_dev), minor(bp->b_dev), 3295 bp->b_data, bp->b_blkno, bp->b_pblkno); 3296 if (bp->b_npages) { 3297 int i; 3298 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 3299 for (i = 0; i < bp->b_npages; i++) { 3300 vm_page_t m; 3301 m = bp->b_pages[i]; 3302 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 3303 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 3304 if ((i + 1) < bp->b_npages) 3305 db_printf(","); 3306 } 3307 db_printf("\n"); 3308 } 3309 } 3310 #endif /* DDB */ 3311