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 1.17 2004/01/20 05:04:06 dillon 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 (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 /* 147 * Disable background writes for now. There appear to be races in the 148 * flags tests and locking operations as well as races in the completion 149 * code modifying the original bp (origbp) without holding a lock, assuming 150 * splbio protection when there might not be splbio protection. 151 */ 152 static int dobkgrdwrite = 0; 153 SYSCTL_INT(_debug, OID_AUTO, dobkgrdwrite, CTLFLAG_RW, &dobkgrdwrite, 0, 154 "Do background writes (honoring the BV_BKGRDWRITE flag)?"); 155 156 static int bufhashmask; 157 static LIST_HEAD(bufhashhdr, buf) *bufhashtbl, invalhash; 158 struct bqueues bufqueues[BUFFER_QUEUES] = { { 0 } }; 159 char *buf_wmesg = BUF_WMESG; 160 161 extern int vm_swap_size; 162 163 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 164 #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */ 165 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ 166 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 167 168 /* 169 * Buffer hash table code. Note that the logical block scans linearly, which 170 * gives us some L1 cache locality. 171 */ 172 173 static __inline 174 struct bufhashhdr * 175 bufhash(struct vnode *vnp, daddr_t bn) 176 { 177 return(&bufhashtbl[(((uintptr_t)(vnp) >> 7) + (int)bn) & bufhashmask]); 178 } 179 180 /* 181 * numdirtywakeup: 182 * 183 * If someone is blocked due to there being too many dirty buffers, 184 * and numdirtybuffers is now reasonable, wake them up. 185 */ 186 187 static __inline void 188 numdirtywakeup(int level) 189 { 190 if (numdirtybuffers <= level) { 191 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) { 192 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH; 193 wakeup(&needsbuffer); 194 } 195 } 196 } 197 198 /* 199 * bufspacewakeup: 200 * 201 * Called when buffer space is potentially available for recovery. 202 * getnewbuf() will block on this flag when it is unable to free 203 * sufficient buffer space. Buffer space becomes recoverable when 204 * bp's get placed back in the queues. 205 */ 206 207 static __inline void 208 bufspacewakeup(void) 209 { 210 /* 211 * If someone is waiting for BUF space, wake them up. Even 212 * though we haven't freed the kva space yet, the waiting 213 * process will be able to now. 214 */ 215 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) { 216 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE; 217 wakeup(&needsbuffer); 218 } 219 } 220 221 /* 222 * runningbufwakeup() - in-progress I/O accounting. 223 * 224 */ 225 static __inline void 226 runningbufwakeup(struct buf *bp) 227 { 228 if (bp->b_runningbufspace) { 229 runningbufspace -= bp->b_runningbufspace; 230 bp->b_runningbufspace = 0; 231 if (runningbufreq && runningbufspace <= lorunningspace) { 232 runningbufreq = 0; 233 wakeup(&runningbufreq); 234 } 235 } 236 } 237 238 /* 239 * bufcountwakeup: 240 * 241 * Called when a buffer has been added to one of the free queues to 242 * account for the buffer and to wakeup anyone waiting for free buffers. 243 * This typically occurs when large amounts of metadata are being handled 244 * by the buffer cache ( else buffer space runs out first, usually ). 245 */ 246 247 static __inline void 248 bufcountwakeup(void) 249 { 250 ++numfreebuffers; 251 if (needsbuffer) { 252 needsbuffer &= ~VFS_BIO_NEED_ANY; 253 if (numfreebuffers >= hifreebuffers) 254 needsbuffer &= ~VFS_BIO_NEED_FREE; 255 wakeup(&needsbuffer); 256 } 257 } 258 259 /* 260 * waitrunningbufspace() 261 * 262 * runningbufspace is a measure of the amount of I/O currently 263 * running. This routine is used in async-write situations to 264 * prevent creating huge backups of pending writes to a device. 265 * Only asynchronous writes are governed by this function. 266 * 267 * Reads will adjust runningbufspace, but will not block based on it. 268 * The read load has a side effect of reducing the allowed write load. 269 * 270 * This does NOT turn an async write into a sync write. It waits 271 * for earlier writes to complete and generally returns before the 272 * caller's write has reached the device. 273 */ 274 static __inline void 275 waitrunningbufspace(void) 276 { 277 while (runningbufspace > hirunningspace) { 278 int s; 279 280 s = splbio(); /* fix race against interrupt/biodone() */ 281 ++runningbufreq; 282 tsleep(&runningbufreq, 0, "wdrain", 0); 283 splx(s); 284 } 285 } 286 287 /* 288 * vfs_buf_test_cache: 289 * 290 * Called when a buffer is extended. This function clears the B_CACHE 291 * bit if the newly extended portion of the buffer does not contain 292 * valid data. 293 */ 294 static __inline__ 295 void 296 vfs_buf_test_cache(struct buf *bp, 297 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 298 vm_page_t m) 299 { 300 if (bp->b_flags & B_CACHE) { 301 int base = (foff + off) & PAGE_MASK; 302 if (vm_page_is_valid(m, base, size) == 0) 303 bp->b_flags &= ~B_CACHE; 304 } 305 } 306 307 static __inline__ 308 void 309 bd_wakeup(int dirtybuflevel) 310 { 311 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) { 312 bd_request = 1; 313 wakeup(&bd_request); 314 } 315 } 316 317 /* 318 * bd_speedup - speedup the buffer cache flushing code 319 */ 320 321 static __inline__ 322 void 323 bd_speedup(void) 324 { 325 bd_wakeup(1); 326 } 327 328 /* 329 * Initialize buffer headers and related structures. 330 */ 331 332 caddr_t 333 bufhashinit(caddr_t vaddr) 334 { 335 /* first, make a null hash table */ 336 for (bufhashmask = 8; bufhashmask < nbuf / 4; bufhashmask <<= 1) 337 ; 338 bufhashtbl = (void *)vaddr; 339 vaddr = vaddr + sizeof(*bufhashtbl) * bufhashmask; 340 --bufhashmask; 341 return(vaddr); 342 } 343 344 void 345 bufinit(void) 346 { 347 struct buf *bp; 348 int i; 349 350 TAILQ_INIT(&bswlist); 351 LIST_INIT(&invalhash); 352 lwkt_inittoken(&buftimetoken); 353 354 for (i = 0; i <= bufhashmask; i++) 355 LIST_INIT(&bufhashtbl[i]); 356 357 /* next, make a null set of free lists */ 358 for (i = 0; i < BUFFER_QUEUES; i++) 359 TAILQ_INIT(&bufqueues[i]); 360 361 /* finally, initialize each buffer header and stick on empty q */ 362 for (i = 0; i < nbuf; i++) { 363 bp = &buf[i]; 364 bzero(bp, sizeof *bp); 365 bp->b_flags = B_INVAL; /* we're just an empty header */ 366 bp->b_dev = NODEV; 367 bp->b_qindex = QUEUE_EMPTY; 368 bp->b_xflags = 0; 369 LIST_INIT(&bp->b_dep); 370 BUF_LOCKINIT(bp); 371 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 372 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 373 } 374 375 /* 376 * maxbufspace is the absolute maximum amount of buffer space we are 377 * allowed to reserve in KVM and in real terms. The absolute maximum 378 * is nominally used by buf_daemon. hibufspace is the nominal maximum 379 * used by most other processes. The differential is required to 380 * ensure that buf_daemon is able to run when other processes might 381 * be blocked waiting for buffer space. 382 * 383 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 384 * this may result in KVM fragmentation which is not handled optimally 385 * by the system. 386 */ 387 maxbufspace = nbuf * BKVASIZE; 388 hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 389 lobufspace = hibufspace - MAXBSIZE; 390 391 lorunningspace = 512 * 1024; 392 hirunningspace = 1024 * 1024; 393 394 /* 395 * Limit the amount of malloc memory since it is wired permanently into 396 * the kernel space. Even though this is accounted for in the buffer 397 * allocation, we don't want the malloced region to grow uncontrolled. 398 * The malloc scheme improves memory utilization significantly on average 399 * (small) directories. 400 */ 401 maxbufmallocspace = hibufspace / 20; 402 403 /* 404 * Reduce the chance of a deadlock occuring by limiting the number 405 * of delayed-write dirty buffers we allow to stack up. 406 */ 407 hidirtybuffers = nbuf / 4 + 20; 408 numdirtybuffers = 0; 409 /* 410 * To support extreme low-memory systems, make sure hidirtybuffers cannot 411 * eat up all available buffer space. This occurs when our minimum cannot 412 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 413 * BKVASIZE'd (8K) buffers. 414 */ 415 while (hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 416 hidirtybuffers >>= 1; 417 } 418 lodirtybuffers = hidirtybuffers / 2; 419 420 /* 421 * Try to keep the number of free buffers in the specified range, 422 * and give special processes (e.g. like buf_daemon) access to an 423 * emergency reserve. 424 */ 425 lofreebuffers = nbuf / 18 + 5; 426 hifreebuffers = 2 * lofreebuffers; 427 numfreebuffers = nbuf; 428 429 /* 430 * Maximum number of async ops initiated per buf_daemon loop. This is 431 * somewhat of a hack at the moment, we really need to limit ourselves 432 * based on the number of bytes of I/O in-transit that were initiated 433 * from buf_daemon. 434 */ 435 436 bogus_offset = kmem_alloc_pageable(kernel_map, PAGE_SIZE); 437 bogus_page = vm_page_alloc(kernel_object, 438 ((bogus_offset - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 439 VM_ALLOC_NORMAL); 440 vmstats.v_wire_count++; 441 442 } 443 444 /* 445 * bfreekva() - free the kva allocation for a buffer. 446 * 447 * Must be called at splbio() or higher as this is the only locking for 448 * buffer_map. 449 * 450 * Since this call frees up buffer space, we call bufspacewakeup(). 451 */ 452 static void 453 bfreekva(struct buf * bp) 454 { 455 int count; 456 457 if (bp->b_kvasize) { 458 ++buffreekvacnt; 459 count = vm_map_entry_reserve(MAP_RESERVE_COUNT); 460 vm_map_lock(buffer_map); 461 bufspace -= bp->b_kvasize; 462 vm_map_delete(buffer_map, 463 (vm_offset_t) bp->b_kvabase, 464 (vm_offset_t) bp->b_kvabase + bp->b_kvasize, 465 &count 466 ); 467 vm_map_unlock(buffer_map); 468 vm_map_entry_release(count); 469 bp->b_kvasize = 0; 470 bufspacewakeup(); 471 } 472 } 473 474 /* 475 * bremfree: 476 * 477 * Remove the buffer from the appropriate free list. 478 */ 479 void 480 bremfree(struct buf * bp) 481 { 482 int s = splbio(); 483 int old_qindex = bp->b_qindex; 484 485 if (bp->b_qindex != QUEUE_NONE) { 486 KASSERT(BUF_REFCNT(bp) == 1, ("bremfree: bp %p not locked",bp)); 487 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 488 bp->b_qindex = QUEUE_NONE; 489 } else { 490 if (BUF_REFCNT(bp) <= 1) 491 panic("bremfree: removing a buffer not on a queue"); 492 } 493 494 /* 495 * Fixup numfreebuffers count. If the buffer is invalid or not 496 * delayed-write, and it was on the EMPTY, LRU, or AGE queues, 497 * the buffer was free and we must decrement numfreebuffers. 498 */ 499 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { 500 switch(old_qindex) { 501 case QUEUE_DIRTY: 502 case QUEUE_CLEAN: 503 case QUEUE_EMPTY: 504 case QUEUE_EMPTYKVA: 505 --numfreebuffers; 506 break; 507 default: 508 break; 509 } 510 } 511 splx(s); 512 } 513 514 515 /* 516 * Get a buffer with the specified data. Look in the cache first. We 517 * must clear B_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 518 * is set, the buffer is valid and we do not have to do anything ( see 519 * getblk() ). 520 */ 521 int 522 bread(struct vnode * vp, daddr_t blkno, int size, struct buf ** bpp) 523 { 524 struct buf *bp; 525 526 bp = getblk(vp, blkno, size, 0, 0); 527 *bpp = bp; 528 529 /* if not found in cache, do some I/O */ 530 if ((bp->b_flags & B_CACHE) == 0) { 531 KASSERT(!(bp->b_flags & B_ASYNC), ("bread: illegal async bp %p", bp)); 532 bp->b_flags |= B_READ; 533 bp->b_flags &= ~(B_ERROR | B_INVAL); 534 vfs_busy_pages(bp, 0); 535 VOP_STRATEGY(vp, bp); 536 return (biowait(bp)); 537 } 538 return (0); 539 } 540 541 /* 542 * Operates like bread, but also starts asynchronous I/O on 543 * read-ahead blocks. We must clear B_ERROR and B_INVAL prior 544 * to initiating I/O . If B_CACHE is set, the buffer is valid 545 * and we do not have to do anything. 546 */ 547 int 548 breadn(struct vnode * vp, daddr_t blkno, int size, daddr_t * rablkno, 549 int *rabsize, int cnt, struct buf ** bpp) 550 { 551 struct buf *bp, *rabp; 552 int i; 553 int rv = 0, readwait = 0; 554 555 *bpp = bp = getblk(vp, blkno, size, 0, 0); 556 557 /* if not found in cache, do some I/O */ 558 if ((bp->b_flags & B_CACHE) == 0) { 559 bp->b_flags |= B_READ; 560 bp->b_flags &= ~(B_ERROR | B_INVAL); 561 vfs_busy_pages(bp, 0); 562 VOP_STRATEGY(vp, bp); 563 ++readwait; 564 } 565 566 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 567 if (inmem(vp, *rablkno)) 568 continue; 569 rabp = getblk(vp, *rablkno, *rabsize, 0, 0); 570 571 if ((rabp->b_flags & B_CACHE) == 0) { 572 rabp->b_flags |= B_READ | B_ASYNC; 573 rabp->b_flags &= ~(B_ERROR | B_INVAL); 574 vfs_busy_pages(rabp, 0); 575 BUF_KERNPROC(rabp); 576 VOP_STRATEGY(vp, rabp); 577 } else { 578 brelse(rabp); 579 } 580 } 581 582 if (readwait) { 583 rv = biowait(bp); 584 } 585 return (rv); 586 } 587 588 /* 589 * Write, release buffer on completion. (Done by iodone 590 * if async). Do not bother writing anything if the buffer 591 * is invalid. 592 * 593 * Note that we set B_CACHE here, indicating that buffer is 594 * fully valid and thus cacheable. This is true even of NFS 595 * now so we set it generally. This could be set either here 596 * or in biodone() since the I/O is synchronous. We put it 597 * here. 598 */ 599 int 600 bwrite(struct buf * bp) 601 { 602 int oldflags, s; 603 struct buf *newbp; 604 605 if (bp->b_flags & B_INVAL) { 606 brelse(bp); 607 return (0); 608 } 609 610 oldflags = bp->b_flags; 611 612 if (BUF_REFCNT(bp) == 0) 613 panic("bwrite: buffer is not busy???"); 614 s = splbio(); 615 /* 616 * If a background write is already in progress, delay 617 * writing this block if it is asynchronous. Otherwise 618 * wait for the background write to complete. 619 */ 620 if (bp->b_xflags & BX_BKGRDINPROG) { 621 if (bp->b_flags & B_ASYNC) { 622 splx(s); 623 bdwrite(bp); 624 return (0); 625 } 626 bp->b_xflags |= BX_BKGRDWAIT; 627 tsleep(&bp->b_xflags, 0, "biord", 0); 628 if (bp->b_xflags & BX_BKGRDINPROG) 629 panic("bwrite: still writing"); 630 } 631 632 /* Mark the buffer clean */ 633 bundirty(bp); 634 635 /* 636 * If this buffer is marked for background writing and we 637 * do not have to wait for it, make a copy and write the 638 * copy so as to leave this buffer ready for further use. 639 * 640 * This optimization eats a lot of memory. If we have a page 641 * or buffer shortfull we can't do it. 642 */ 643 if (dobkgrdwrite && 644 (bp->b_xflags & BX_BKGRDWRITE) && 645 (bp->b_flags & B_ASYNC) && 646 !vm_page_count_severe() && 647 !buf_dirty_count_severe()) { 648 if (bp->b_flags & B_CALL) 649 panic("bwrite: need chained iodone"); 650 651 /* get a new block */ 652 newbp = geteblk(bp->b_bufsize); 653 654 /* set it to be identical to the old block */ 655 memcpy(newbp->b_data, bp->b_data, bp->b_bufsize); 656 bgetvp(bp->b_vp, newbp); 657 newbp->b_lblkno = bp->b_lblkno; 658 newbp->b_blkno = bp->b_blkno; 659 newbp->b_offset = bp->b_offset; 660 newbp->b_iodone = vfs_backgroundwritedone; 661 newbp->b_flags |= B_ASYNC | B_CALL; 662 newbp->b_flags &= ~B_INVAL; 663 664 /* move over the dependencies */ 665 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_movedeps) 666 (*bioops.io_movedeps)(bp, newbp); 667 668 /* 669 * Initiate write on the copy, release the original to 670 * the B_LOCKED queue so that it cannot go away until 671 * the background write completes. If not locked it could go 672 * away and then be reconstituted while it was being written. 673 * If the reconstituted buffer were written, we could end up 674 * with two background copies being written at the same time. 675 */ 676 bp->b_xflags |= BX_BKGRDINPROG; 677 bp->b_flags |= B_LOCKED; 678 bqrelse(bp); 679 bp = newbp; 680 } 681 682 bp->b_flags &= ~(B_READ | B_DONE | B_ERROR); 683 bp->b_flags |= B_WRITEINPROG | B_CACHE; 684 685 bp->b_vp->v_numoutput++; 686 vfs_busy_pages(bp, 1); 687 688 /* 689 * Normal bwrites pipeline writes 690 */ 691 bp->b_runningbufspace = bp->b_bufsize; 692 runningbufspace += bp->b_runningbufspace; 693 694 splx(s); 695 if (oldflags & B_ASYNC) 696 BUF_KERNPROC(bp); 697 VOP_STRATEGY(bp->b_vp, bp); 698 699 if ((oldflags & B_ASYNC) == 0) { 700 int rtval = biowait(bp); 701 brelse(bp); 702 return (rtval); 703 } else if ((oldflags & B_NOWDRAIN) == 0) { 704 /* 705 * don't allow the async write to saturate the I/O 706 * system. Deadlocks can occur only if a device strategy 707 * routine (like in VN) turns around and issues another 708 * high-level write, in which case B_NOWDRAIN is expected 709 * to be set. Otherwise we will not deadlock here because 710 * we are blocking waiting for I/O that is already in-progress 711 * to complete. 712 */ 713 waitrunningbufspace(); 714 } 715 716 return (0); 717 } 718 719 /* 720 * Complete a background write started from bwrite. 721 */ 722 static void 723 vfs_backgroundwritedone(bp) 724 struct buf *bp; 725 { 726 struct buf *origbp; 727 728 /* 729 * Find the original buffer that we are writing. 730 */ 731 if ((origbp = gbincore(bp->b_vp, bp->b_lblkno)) == NULL) 732 panic("backgroundwritedone: lost buffer"); 733 /* 734 * Process dependencies then return any unfinished ones. 735 */ 736 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_complete) 737 (*bioops.io_complete)(bp); 738 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_movedeps) 739 (*bioops.io_movedeps)(bp, origbp); 740 /* 741 * Clear the BX_BKGRDINPROG flag in the original buffer 742 * and awaken it if it is waiting for the write to complete. 743 * If BX_BKGRDINPROG is not set in the original buffer it must 744 * have been released and re-instantiated - which is not legal. 745 */ 746 KASSERT((origbp->b_xflags & BX_BKGRDINPROG), ("backgroundwritedone: lost buffer2")); 747 origbp->b_xflags &= ~BX_BKGRDINPROG; 748 if (origbp->b_xflags & BX_BKGRDWAIT) { 749 origbp->b_xflags &= ~BX_BKGRDWAIT; 750 wakeup(&origbp->b_xflags); 751 } 752 /* 753 * Clear the B_LOCKED flag and remove it from the locked 754 * queue if it currently resides there. 755 */ 756 origbp->b_flags &= ~B_LOCKED; 757 if (BUF_LOCK(origbp, LK_EXCLUSIVE | LK_NOWAIT) == 0) { 758 bremfree(origbp); 759 bqrelse(origbp); 760 } 761 /* 762 * This buffer is marked B_NOCACHE, so when it is released 763 * by biodone, it will be tossed. We mark it with B_READ 764 * to avoid biodone doing a second vwakeup. 765 */ 766 bp->b_flags |= B_NOCACHE | B_READ; 767 bp->b_flags &= ~(B_CACHE | B_CALL | B_DONE); 768 bp->b_iodone = 0; 769 biodone(bp); 770 } 771 772 /* 773 * Delayed write. (Buffer is marked dirty). Do not bother writing 774 * anything if the buffer is marked invalid. 775 * 776 * Note that since the buffer must be completely valid, we can safely 777 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 778 * biodone() in order to prevent getblk from writing the buffer 779 * out synchronously. 780 */ 781 void 782 bdwrite(struct buf * bp) 783 { 784 if (BUF_REFCNT(bp) == 0) 785 panic("bdwrite: buffer is not busy"); 786 787 if (bp->b_flags & B_INVAL) { 788 brelse(bp); 789 return; 790 } 791 bdirty(bp); 792 793 /* 794 * Set B_CACHE, indicating that the buffer is fully valid. This is 795 * true even of NFS now. 796 */ 797 bp->b_flags |= B_CACHE; 798 799 /* 800 * This bmap keeps the system from needing to do the bmap later, 801 * perhaps when the system is attempting to do a sync. Since it 802 * is likely that the indirect block -- or whatever other datastructure 803 * that the filesystem needs is still in memory now, it is a good 804 * thing to do this. Note also, that if the pageout daemon is 805 * requesting a sync -- there might not be enough memory to do 806 * the bmap then... So, this is important to do. 807 */ 808 if (bp->b_lblkno == bp->b_blkno) { 809 VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 810 } 811 812 /* 813 * Set the *dirty* buffer range based upon the VM system dirty pages. 814 */ 815 vfs_setdirty(bp); 816 817 /* 818 * We need to do this here to satisfy the vnode_pager and the 819 * pageout daemon, so that it thinks that the pages have been 820 * "cleaned". Note that since the pages are in a delayed write 821 * buffer -- the VFS layer "will" see that the pages get written 822 * out on the next sync, or perhaps the cluster will be completed. 823 */ 824 vfs_clean_pages(bp); 825 bqrelse(bp); 826 827 /* 828 * Wakeup the buffer flushing daemon if we have a lot of dirty 829 * buffers (midpoint between our recovery point and our stall 830 * point). 831 */ 832 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 833 834 /* 835 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 836 * due to the softdep code. 837 */ 838 } 839 840 /* 841 * bdirty: 842 * 843 * Turn buffer into delayed write request. We must clear B_READ and 844 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 845 * itself to properly update it in the dirty/clean lists. We mark it 846 * B_DONE to ensure that any asynchronization of the buffer properly 847 * clears B_DONE ( else a panic will occur later ). 848 * 849 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 850 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 851 * should only be called if the buffer is known-good. 852 * 853 * Since the buffer is not on a queue, we do not update the numfreebuffers 854 * count. 855 * 856 * Must be called at splbio(). 857 * The buffer must be on QUEUE_NONE. 858 */ 859 void 860 bdirty(bp) 861 struct buf *bp; 862 { 863 KASSERT(bp->b_qindex == QUEUE_NONE, ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 864 bp->b_flags &= ~(B_READ|B_RELBUF); 865 866 if ((bp->b_flags & B_DELWRI) == 0) { 867 bp->b_flags |= B_DONE | B_DELWRI; 868 reassignbuf(bp, bp->b_vp); 869 ++numdirtybuffers; 870 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 871 } 872 } 873 874 /* 875 * bundirty: 876 * 877 * Clear B_DELWRI for buffer. 878 * 879 * Since the buffer is not on a queue, we do not update the numfreebuffers 880 * count. 881 * 882 * Must be called at splbio(). 883 * The buffer must be on QUEUE_NONE. 884 */ 885 886 void 887 bundirty(bp) 888 struct buf *bp; 889 { 890 KASSERT(bp->b_qindex == QUEUE_NONE, ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 891 892 if (bp->b_flags & B_DELWRI) { 893 bp->b_flags &= ~B_DELWRI; 894 reassignbuf(bp, bp->b_vp); 895 --numdirtybuffers; 896 numdirtywakeup(lodirtybuffers); 897 } 898 /* 899 * Since it is now being written, we can clear its deferred write flag. 900 */ 901 bp->b_flags &= ~B_DEFERRED; 902 } 903 904 /* 905 * bawrite: 906 * 907 * Asynchronous write. Start output on a buffer, but do not wait for 908 * it to complete. The buffer is released when the output completes. 909 * 910 * bwrite() ( or the VOP routine anyway ) is responsible for handling 911 * B_INVAL buffers. Not us. 912 */ 913 void 914 bawrite(struct buf * bp) 915 { 916 bp->b_flags |= B_ASYNC; 917 (void) VOP_BWRITE(bp->b_vp, bp); 918 } 919 920 /* 921 * bowrite: 922 * 923 * Ordered write. Start output on a buffer, and flag it so that the 924 * device will write it in the order it was queued. The buffer is 925 * released when the output completes. bwrite() ( or the VOP routine 926 * anyway ) is responsible for handling B_INVAL buffers. 927 */ 928 int 929 bowrite(struct buf * bp) 930 { 931 bp->b_flags |= B_ORDERED | B_ASYNC; 932 return (VOP_BWRITE(bp->b_vp, bp)); 933 } 934 935 /* 936 * bwillwrite: 937 * 938 * Called prior to the locking of any vnodes when we are expecting to 939 * write. We do not want to starve the buffer cache with too many 940 * dirty buffers so we block here. By blocking prior to the locking 941 * of any vnodes we attempt to avoid the situation where a locked vnode 942 * prevents the various system daemons from flushing related buffers. 943 */ 944 945 void 946 bwillwrite(void) 947 { 948 if (numdirtybuffers >= hidirtybuffers) { 949 int s; 950 951 s = splbio(); 952 while (numdirtybuffers >= hidirtybuffers) { 953 bd_wakeup(1); 954 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH; 955 tsleep(&needsbuffer, 0, "flswai", 0); 956 } 957 splx(s); 958 } 959 } 960 961 /* 962 * Return true if we have too many dirty buffers. 963 */ 964 int 965 buf_dirty_count_severe(void) 966 { 967 return(numdirtybuffers >= hidirtybuffers); 968 } 969 970 /* 971 * brelse: 972 * 973 * Release a busy buffer and, if requested, free its resources. The 974 * buffer will be stashed in the appropriate bufqueue[] allowing it 975 * to be accessed later as a cache entity or reused for other purposes. 976 */ 977 void 978 brelse(struct buf * bp) 979 { 980 int s; 981 982 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 983 984 s = splbio(); 985 986 if (bp->b_flags & B_LOCKED) 987 bp->b_flags &= ~B_ERROR; 988 989 if ((bp->b_flags & (B_READ | B_ERROR | B_INVAL)) == B_ERROR) { 990 /* 991 * Failed write, redirty. Must clear B_ERROR to prevent 992 * pages from being scrapped. If B_INVAL is set then 993 * this case is not run and the next case is run to 994 * destroy the buffer. B_INVAL can occur if the buffer 995 * is outside the range supported by the underlying device. 996 */ 997 bp->b_flags &= ~B_ERROR; 998 bdirty(bp); 999 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR | B_FREEBUF)) || 1000 (bp->b_bufsize <= 0)) { 1001 /* 1002 * Either a failed I/O or we were asked to free or not 1003 * cache the buffer. 1004 */ 1005 bp->b_flags |= B_INVAL; 1006 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_deallocate) 1007 (*bioops.io_deallocate)(bp); 1008 if (bp->b_flags & B_DELWRI) { 1009 --numdirtybuffers; 1010 numdirtywakeup(lodirtybuffers); 1011 } 1012 bp->b_flags &= ~(B_DELWRI | B_CACHE | B_FREEBUF); 1013 if ((bp->b_flags & B_VMIO) == 0) { 1014 if (bp->b_bufsize) 1015 allocbuf(bp, 0); 1016 if (bp->b_vp) 1017 brelvp(bp); 1018 } 1019 } 1020 1021 /* 1022 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1023 * is called with B_DELWRI set, the underlying pages may wind up 1024 * getting freed causing a previous write (bdwrite()) to get 'lost' 1025 * because pages associated with a B_DELWRI bp are marked clean. 1026 * 1027 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1028 * if B_DELWRI is set. 1029 * 1030 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1031 * on pages to return pages to the VM page queues. 1032 */ 1033 if (bp->b_flags & B_DELWRI) 1034 bp->b_flags &= ~B_RELBUF; 1035 else if (vm_page_count_severe() && !(bp->b_xflags & BX_BKGRDINPROG)) 1036 bp->b_flags |= B_RELBUF; 1037 1038 /* 1039 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1040 * constituted, not even NFS buffers now. Two flags effect this. If 1041 * B_INVAL, the struct buf is invalidated but the VM object is kept 1042 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1043 * 1044 * If B_ERROR or B_NOCACHE is set, pages in the VM object will be 1045 * invalidated. B_ERROR cannot be set for a failed write unless the 1046 * buffer is also B_INVAL because it hits the re-dirtying code above. 1047 * 1048 * Normally we can do this whether a buffer is B_DELWRI or not. If 1049 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1050 * the commit state and we cannot afford to lose the buffer. If the 1051 * buffer has a background write in progress, we need to keep it 1052 * around to prevent it from being reconstituted and starting a second 1053 * background write. 1054 */ 1055 if ((bp->b_flags & B_VMIO) 1056 && !(bp->b_vp->v_tag == VT_NFS && 1057 !vn_isdisk(bp->b_vp, NULL) && 1058 (bp->b_flags & B_DELWRI)) 1059 ) { 1060 1061 int i, j, resid; 1062 vm_page_t m; 1063 off_t foff; 1064 vm_pindex_t poff; 1065 vm_object_t obj; 1066 struct vnode *vp; 1067 1068 vp = bp->b_vp; 1069 1070 /* 1071 * Get the base offset and length of the buffer. Note that 1072 * in the VMIO case if the buffer block size is not 1073 * page-aligned then b_data pointer may not be page-aligned. 1074 * But our b_pages[] array *IS* page aligned. 1075 * 1076 * block sizes less then DEV_BSIZE (usually 512) are not 1077 * supported due to the page granularity bits (m->valid, 1078 * m->dirty, etc...). 1079 * 1080 * See man buf(9) for more information 1081 */ 1082 1083 resid = bp->b_bufsize; 1084 foff = bp->b_offset; 1085 1086 for (i = 0; i < bp->b_npages; i++) { 1087 m = bp->b_pages[i]; 1088 vm_page_flag_clear(m, PG_ZERO); 1089 /* 1090 * If we hit a bogus page, fixup *all* of them 1091 * now. 1092 */ 1093 if (m == bogus_page) { 1094 VOP_GETVOBJECT(vp, &obj); 1095 poff = OFF_TO_IDX(bp->b_offset); 1096 1097 for (j = i; j < bp->b_npages; j++) { 1098 vm_page_t mtmp; 1099 1100 mtmp = bp->b_pages[j]; 1101 if (mtmp == bogus_page) { 1102 mtmp = vm_page_lookup(obj, poff + j); 1103 if (!mtmp) { 1104 panic("brelse: page missing\n"); 1105 } 1106 bp->b_pages[j] = mtmp; 1107 } 1108 } 1109 1110 if ((bp->b_flags & B_INVAL) == 0) { 1111 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 1112 } 1113 m = bp->b_pages[i]; 1114 } 1115 if (bp->b_flags & (B_NOCACHE|B_ERROR)) { 1116 int poffset = foff & PAGE_MASK; 1117 int presid = resid > (PAGE_SIZE - poffset) ? 1118 (PAGE_SIZE - poffset) : resid; 1119 1120 KASSERT(presid >= 0, ("brelse: extra page")); 1121 vm_page_set_invalid(m, poffset, presid); 1122 } 1123 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1124 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1125 } 1126 1127 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1128 vfs_vmio_release(bp); 1129 1130 } else if (bp->b_flags & B_VMIO) { 1131 1132 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1133 vfs_vmio_release(bp); 1134 1135 } 1136 1137 if (bp->b_qindex != QUEUE_NONE) 1138 panic("brelse: free buffer onto another queue???"); 1139 if (BUF_REFCNT(bp) > 1) { 1140 /* Temporary panic to verify exclusive locking */ 1141 /* This panic goes away when we allow shared refs */ 1142 panic("brelse: multiple refs"); 1143 /* do not release to free list */ 1144 BUF_UNLOCK(bp); 1145 splx(s); 1146 return; 1147 } 1148 1149 /* enqueue */ 1150 1151 /* buffers with no memory */ 1152 if (bp->b_bufsize == 0) { 1153 bp->b_flags |= B_INVAL; 1154 bp->b_xflags &= ~BX_BKGRDWRITE; 1155 if (bp->b_xflags & BX_BKGRDINPROG) 1156 panic("losing buffer 1"); 1157 if (bp->b_kvasize) { 1158 bp->b_qindex = QUEUE_EMPTYKVA; 1159 } else { 1160 bp->b_qindex = QUEUE_EMPTY; 1161 } 1162 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1163 LIST_REMOVE(bp, b_hash); 1164 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1165 bp->b_dev = NODEV; 1166 /* buffers with junk contents */ 1167 } else if (bp->b_flags & (B_ERROR | B_INVAL | B_NOCACHE | B_RELBUF)) { 1168 bp->b_flags |= B_INVAL; 1169 bp->b_xflags &= ~BX_BKGRDWRITE; 1170 if (bp->b_xflags & BX_BKGRDINPROG) 1171 panic("losing buffer 2"); 1172 bp->b_qindex = QUEUE_CLEAN; 1173 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1174 LIST_REMOVE(bp, b_hash); 1175 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1176 bp->b_dev = NODEV; 1177 1178 /* buffers that are locked */ 1179 } else if (bp->b_flags & B_LOCKED) { 1180 bp->b_qindex = QUEUE_LOCKED; 1181 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LOCKED], bp, b_freelist); 1182 1183 /* remaining buffers */ 1184 } else { 1185 switch(bp->b_flags & (B_DELWRI|B_AGE)) { 1186 case B_DELWRI | B_AGE: 1187 bp->b_qindex = QUEUE_DIRTY; 1188 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_DIRTY], bp, b_freelist); 1189 break; 1190 case B_DELWRI: 1191 bp->b_qindex = QUEUE_DIRTY; 1192 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist); 1193 break; 1194 case B_AGE: 1195 bp->b_qindex = QUEUE_CLEAN; 1196 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1197 break; 1198 default: 1199 bp->b_qindex = QUEUE_CLEAN; 1200 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1201 break; 1202 } 1203 } 1204 1205 /* 1206 * If B_INVAL, clear B_DELWRI. We've already placed the buffer 1207 * on the correct queue. 1208 */ 1209 if ((bp->b_flags & (B_INVAL|B_DELWRI)) == (B_INVAL|B_DELWRI)) 1210 bundirty(bp); 1211 1212 /* 1213 * Fixup numfreebuffers count. The bp is on an appropriate queue 1214 * unless locked. We then bump numfreebuffers if it is not B_DELWRI. 1215 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1216 * if B_INVAL is set ). 1217 */ 1218 1219 if ((bp->b_flags & B_LOCKED) == 0 && !(bp->b_flags & B_DELWRI)) 1220 bufcountwakeup(); 1221 1222 /* 1223 * Something we can maybe free or reuse 1224 */ 1225 if (bp->b_bufsize || bp->b_kvasize) 1226 bufspacewakeup(); 1227 1228 /* unlock */ 1229 BUF_UNLOCK(bp); 1230 bp->b_flags &= ~(B_ORDERED | B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | 1231 B_DIRECT | B_NOWDRAIN); 1232 splx(s); 1233 } 1234 1235 /* 1236 * Release a buffer back to the appropriate queue but do not try to free 1237 * it. The buffer is expected to be used again soon. 1238 * 1239 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1240 * biodone() to requeue an async I/O on completion. It is also used when 1241 * known good buffers need to be requeued but we think we may need the data 1242 * again soon. 1243 * 1244 * XXX we should be able to leave the B_RELBUF hint set on completion. 1245 */ 1246 void 1247 bqrelse(struct buf * bp) 1248 { 1249 int s; 1250 1251 s = splbio(); 1252 1253 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1254 1255 if (bp->b_qindex != QUEUE_NONE) 1256 panic("bqrelse: free buffer onto another queue???"); 1257 if (BUF_REFCNT(bp) > 1) { 1258 /* do not release to free list */ 1259 panic("bqrelse: multiple refs"); 1260 BUF_UNLOCK(bp); 1261 splx(s); 1262 return; 1263 } 1264 if (bp->b_flags & B_LOCKED) { 1265 bp->b_flags &= ~B_ERROR; 1266 bp->b_qindex = QUEUE_LOCKED; 1267 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LOCKED], bp, b_freelist); 1268 /* buffers with stale but valid contents */ 1269 } else if (bp->b_flags & B_DELWRI) { 1270 bp->b_qindex = QUEUE_DIRTY; 1271 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist); 1272 } else if (vm_page_count_severe()) { 1273 /* 1274 * We are too low on memory, we have to try to free the 1275 * buffer (most importantly: the wired pages making up its 1276 * backing store) *now*. 1277 */ 1278 splx(s); 1279 brelse(bp); 1280 return; 1281 } else { 1282 bp->b_qindex = QUEUE_CLEAN; 1283 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1284 } 1285 1286 if ((bp->b_flags & B_LOCKED) == 0 && 1287 ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI))) { 1288 bufcountwakeup(); 1289 } 1290 1291 /* 1292 * Something we can maybe free or reuse. 1293 */ 1294 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1295 bufspacewakeup(); 1296 1297 /* unlock */ 1298 BUF_UNLOCK(bp); 1299 bp->b_flags &= ~(B_ORDERED | B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1300 splx(s); 1301 } 1302 1303 static void 1304 vfs_vmio_release(bp) 1305 struct buf *bp; 1306 { 1307 int i, s; 1308 vm_page_t m; 1309 1310 s = splvm(); 1311 for (i = 0; i < bp->b_npages; i++) { 1312 m = bp->b_pages[i]; 1313 bp->b_pages[i] = NULL; 1314 /* 1315 * In order to keep page LRU ordering consistent, put 1316 * everything on the inactive queue. 1317 */ 1318 vm_page_unwire(m, 0); 1319 /* 1320 * We don't mess with busy pages, it is 1321 * the responsibility of the process that 1322 * busied the pages to deal with them. 1323 */ 1324 if ((m->flags & PG_BUSY) || (m->busy != 0)) 1325 continue; 1326 1327 if (m->wire_count == 0) { 1328 vm_page_flag_clear(m, PG_ZERO); 1329 /* 1330 * Might as well free the page if we can and it has 1331 * no valid data. We also free the page if the 1332 * buffer was used for direct I/O. 1333 */ 1334 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && m->hold_count == 0) { 1335 vm_page_busy(m); 1336 vm_page_protect(m, VM_PROT_NONE); 1337 vm_page_free(m); 1338 } else if (bp->b_flags & B_DIRECT) { 1339 vm_page_try_to_free(m); 1340 } else if (vm_page_count_severe()) { 1341 vm_page_try_to_cache(m); 1342 } 1343 } 1344 } 1345 splx(s); 1346 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages); 1347 if (bp->b_bufsize) { 1348 bufspacewakeup(); 1349 bp->b_bufsize = 0; 1350 } 1351 bp->b_npages = 0; 1352 bp->b_flags &= ~B_VMIO; 1353 if (bp->b_vp) 1354 brelvp(bp); 1355 } 1356 1357 /* 1358 * Check to see if a block is currently memory resident. 1359 */ 1360 struct buf * 1361 gbincore(struct vnode * vp, daddr_t blkno) 1362 { 1363 struct buf *bp; 1364 struct bufhashhdr *bh; 1365 1366 bh = bufhash(vp, blkno); 1367 1368 /* Search hash chain */ 1369 LIST_FOREACH(bp, bh, b_hash) { 1370 /* hit */ 1371 if (bp->b_vp == vp && bp->b_lblkno == blkno && 1372 (bp->b_flags & B_INVAL) == 0) { 1373 break; 1374 } 1375 } 1376 return (bp); 1377 } 1378 1379 /* 1380 * vfs_bio_awrite: 1381 * 1382 * Implement clustered async writes for clearing out B_DELWRI buffers. 1383 * This is much better then the old way of writing only one buffer at 1384 * a time. Note that we may not be presented with the buffers in the 1385 * correct order, so we search for the cluster in both directions. 1386 */ 1387 int 1388 vfs_bio_awrite(struct buf * bp) 1389 { 1390 int i; 1391 int j; 1392 daddr_t lblkno = bp->b_lblkno; 1393 struct vnode *vp = bp->b_vp; 1394 int s; 1395 int ncl; 1396 struct buf *bpa; 1397 int nwritten; 1398 int size; 1399 int maxcl; 1400 1401 s = splbio(); 1402 /* 1403 * right now we support clustered writing only to regular files. If 1404 * we find a clusterable block we could be in the middle of a cluster 1405 * rather then at the beginning. 1406 */ 1407 if ((vp->v_type == VREG) && 1408 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1409 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1410 1411 size = vp->v_mount->mnt_stat.f_iosize; 1412 maxcl = MAXPHYS / size; 1413 1414 for (i = 1; i < maxcl; i++) { 1415 if ((bpa = gbincore(vp, lblkno + i)) && 1416 BUF_REFCNT(bpa) == 0 && 1417 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == 1418 (B_DELWRI | B_CLUSTEROK)) && 1419 (bpa->b_bufsize == size)) { 1420 if ((bpa->b_blkno == bpa->b_lblkno) || 1421 (bpa->b_blkno != 1422 bp->b_blkno + ((i * size) >> DEV_BSHIFT))) 1423 break; 1424 } else { 1425 break; 1426 } 1427 } 1428 for (j = 1; i + j <= maxcl && j <= lblkno; j++) { 1429 if ((bpa = gbincore(vp, lblkno - j)) && 1430 BUF_REFCNT(bpa) == 0 && 1431 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == 1432 (B_DELWRI | B_CLUSTEROK)) && 1433 (bpa->b_bufsize == size)) { 1434 if ((bpa->b_blkno == bpa->b_lblkno) || 1435 (bpa->b_blkno != 1436 bp->b_blkno - ((j * size) >> DEV_BSHIFT))) 1437 break; 1438 } else { 1439 break; 1440 } 1441 } 1442 --j; 1443 ncl = i + j; 1444 /* 1445 * this is a possible cluster write 1446 */ 1447 if (ncl != 1) { 1448 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl); 1449 splx(s); 1450 return nwritten; 1451 } 1452 } 1453 1454 BUF_LOCK(bp, LK_EXCLUSIVE); 1455 bremfree(bp); 1456 bp->b_flags |= B_ASYNC; 1457 1458 splx(s); 1459 /* 1460 * default (old) behavior, writing out only one block 1461 * 1462 * XXX returns b_bufsize instead of b_bcount for nwritten? 1463 */ 1464 nwritten = bp->b_bufsize; 1465 (void) VOP_BWRITE(bp->b_vp, bp); 1466 1467 return nwritten; 1468 } 1469 1470 /* 1471 * getnewbuf: 1472 * 1473 * Find and initialize a new buffer header, freeing up existing buffers 1474 * in the bufqueues as necessary. The new buffer is returned locked. 1475 * 1476 * Important: B_INVAL is not set. If the caller wishes to throw the 1477 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1478 * 1479 * We block if: 1480 * We have insufficient buffer headers 1481 * We have insufficient buffer space 1482 * buffer_map is too fragmented ( space reservation fails ) 1483 * If we have to flush dirty buffers ( but we try to avoid this ) 1484 * 1485 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1486 * Instead we ask the buf daemon to do it for us. We attempt to 1487 * avoid piecemeal wakeups of the pageout daemon. 1488 */ 1489 1490 static struct buf * 1491 getnewbuf(int slpflag, int slptimeo, int size, int maxsize) 1492 { 1493 struct buf *bp; 1494 struct buf *nbp; 1495 int defrag = 0; 1496 int nqindex; 1497 static int flushingbufs; 1498 1499 /* 1500 * We can't afford to block since we might be holding a vnode lock, 1501 * which may prevent system daemons from running. We deal with 1502 * low-memory situations by proactively returning memory and running 1503 * async I/O rather then sync I/O. 1504 */ 1505 1506 ++getnewbufcalls; 1507 --getnewbufrestarts; 1508 restart: 1509 ++getnewbufrestarts; 1510 1511 /* 1512 * Setup for scan. If we do not have enough free buffers, 1513 * we setup a degenerate case that immediately fails. Note 1514 * that if we are specially marked process, we are allowed to 1515 * dip into our reserves. 1516 * 1517 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 1518 * 1519 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 1520 * However, there are a number of cases (defragging, reusing, ...) 1521 * where we cannot backup. 1522 */ 1523 nqindex = QUEUE_EMPTYKVA; 1524 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 1525 1526 if (nbp == NULL) { 1527 /* 1528 * If no EMPTYKVA buffers and we are either 1529 * defragging or reusing, locate a CLEAN buffer 1530 * to free or reuse. If bufspace useage is low 1531 * skip this step so we can allocate a new buffer. 1532 */ 1533 if (defrag || bufspace >= lobufspace) { 1534 nqindex = QUEUE_CLEAN; 1535 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 1536 } 1537 1538 /* 1539 * If we could not find or were not allowed to reuse a 1540 * CLEAN buffer, check to see if it is ok to use an EMPTY 1541 * buffer. We can only use an EMPTY buffer if allocating 1542 * its KVA would not otherwise run us out of buffer space. 1543 */ 1544 if (nbp == NULL && defrag == 0 && 1545 bufspace + maxsize < hibufspace) { 1546 nqindex = QUEUE_EMPTY; 1547 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1548 } 1549 } 1550 1551 /* 1552 * Run scan, possibly freeing data and/or kva mappings on the fly 1553 * depending. 1554 */ 1555 1556 while ((bp = nbp) != NULL) { 1557 int qindex = nqindex; 1558 1559 /* 1560 * Calculate next bp ( we can only use it if we do not block 1561 * or do other fancy things ). 1562 */ 1563 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 1564 switch(qindex) { 1565 case QUEUE_EMPTY: 1566 nqindex = QUEUE_EMPTYKVA; 1567 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]))) 1568 break; 1569 /* fall through */ 1570 case QUEUE_EMPTYKVA: 1571 nqindex = QUEUE_CLEAN; 1572 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]))) 1573 break; 1574 /* fall through */ 1575 case QUEUE_CLEAN: 1576 /* 1577 * nbp is NULL. 1578 */ 1579 break; 1580 } 1581 } 1582 1583 /* 1584 * Sanity Checks 1585 */ 1586 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp)); 1587 1588 /* 1589 * Note: we no longer distinguish between VMIO and non-VMIO 1590 * buffers. 1591 */ 1592 1593 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); 1594 1595 /* 1596 * If we are defragging then we need a buffer with 1597 * b_kvasize != 0. XXX this situation should no longer 1598 * occur, if defrag is non-zero the buffer's b_kvasize 1599 * should also be non-zero at this point. XXX 1600 */ 1601 if (defrag && bp->b_kvasize == 0) { 1602 printf("Warning: defrag empty buffer %p\n", bp); 1603 continue; 1604 } 1605 1606 /* 1607 * Start freeing the bp. This is somewhat involved. nbp 1608 * remains valid only for QUEUE_EMPTY[KVA] bp's. 1609 */ 1610 1611 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) 1612 panic("getnewbuf: locked buf"); 1613 bremfree(bp); 1614 1615 if (qindex == QUEUE_CLEAN) { 1616 if (bp->b_flags & B_VMIO) { 1617 bp->b_flags &= ~B_ASYNC; 1618 vfs_vmio_release(bp); 1619 } 1620 if (bp->b_vp) 1621 brelvp(bp); 1622 } 1623 1624 /* 1625 * NOTE: nbp is now entirely invalid. We can only restart 1626 * the scan from this point on. 1627 * 1628 * Get the rest of the buffer freed up. b_kva* is still 1629 * valid after this operation. 1630 */ 1631 1632 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_deallocate) 1633 (*bioops.io_deallocate)(bp); 1634 if (bp->b_xflags & BX_BKGRDINPROG) 1635 panic("losing buffer 3"); 1636 LIST_REMOVE(bp, b_hash); 1637 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1638 1639 if (bp->b_bufsize) 1640 allocbuf(bp, 0); 1641 1642 bp->b_flags = 0; 1643 bp->b_xflags = 0; 1644 bp->b_dev = NODEV; 1645 bp->b_vp = NULL; 1646 bp->b_blkno = bp->b_lblkno = 0; 1647 bp->b_offset = NOOFFSET; 1648 bp->b_iodone = 0; 1649 bp->b_error = 0; 1650 bp->b_resid = 0; 1651 bp->b_bcount = 0; 1652 bp->b_npages = 0; 1653 bp->b_dirtyoff = bp->b_dirtyend = 0; 1654 1655 LIST_INIT(&bp->b_dep); 1656 1657 /* 1658 * If we are defragging then free the buffer. 1659 */ 1660 if (defrag) { 1661 bp->b_flags |= B_INVAL; 1662 bfreekva(bp); 1663 brelse(bp); 1664 defrag = 0; 1665 goto restart; 1666 } 1667 1668 /* 1669 * If we are overcomitted then recover the buffer and its 1670 * KVM space. This occurs in rare situations when multiple 1671 * processes are blocked in getnewbuf() or allocbuf(). 1672 */ 1673 if (bufspace >= hibufspace) 1674 flushingbufs = 1; 1675 if (flushingbufs && bp->b_kvasize != 0) { 1676 bp->b_flags |= B_INVAL; 1677 bfreekva(bp); 1678 brelse(bp); 1679 goto restart; 1680 } 1681 if (bufspace < lobufspace) 1682 flushingbufs = 0; 1683 break; 1684 } 1685 1686 /* 1687 * If we exhausted our list, sleep as appropriate. We may have to 1688 * wakeup various daemons and write out some dirty buffers. 1689 * 1690 * Generally we are sleeping due to insufficient buffer space. 1691 */ 1692 1693 if (bp == NULL) { 1694 int flags; 1695 char *waitmsg; 1696 1697 if (defrag) { 1698 flags = VFS_BIO_NEED_BUFSPACE; 1699 waitmsg = "nbufkv"; 1700 } else if (bufspace >= hibufspace) { 1701 waitmsg = "nbufbs"; 1702 flags = VFS_BIO_NEED_BUFSPACE; 1703 } else { 1704 waitmsg = "newbuf"; 1705 flags = VFS_BIO_NEED_ANY; 1706 } 1707 1708 bd_speedup(); /* heeeelp */ 1709 1710 needsbuffer |= flags; 1711 while (needsbuffer & flags) { 1712 if (tsleep(&needsbuffer, slpflag, waitmsg, slptimeo)) 1713 return (NULL); 1714 } 1715 } else { 1716 /* 1717 * We finally have a valid bp. We aren't quite out of the 1718 * woods, we still have to reserve kva space. In order 1719 * to keep fragmentation sane we only allocate kva in 1720 * BKVASIZE chunks. 1721 */ 1722 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 1723 1724 if (maxsize != bp->b_kvasize) { 1725 vm_offset_t addr = 0; 1726 int count; 1727 1728 bfreekva(bp); 1729 1730 count = vm_map_entry_reserve(MAP_RESERVE_COUNT); 1731 vm_map_lock(buffer_map); 1732 1733 if (vm_map_findspace(buffer_map, 1734 vm_map_min(buffer_map), maxsize, 1735 maxsize, &addr)) { 1736 /* 1737 * Uh oh. Buffer map is to fragmented. We 1738 * must defragment the map. 1739 */ 1740 vm_map_unlock(buffer_map); 1741 vm_map_entry_release(count); 1742 ++bufdefragcnt; 1743 defrag = 1; 1744 bp->b_flags |= B_INVAL; 1745 brelse(bp); 1746 goto restart; 1747 } 1748 if (addr) { 1749 vm_map_insert(buffer_map, &count, 1750 NULL, 0, 1751 addr, addr + maxsize, 1752 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT); 1753 1754 bp->b_kvabase = (caddr_t) addr; 1755 bp->b_kvasize = maxsize; 1756 bufspace += bp->b_kvasize; 1757 ++bufreusecnt; 1758 } 1759 vm_map_unlock(buffer_map); 1760 vm_map_entry_release(count); 1761 } 1762 bp->b_data = bp->b_kvabase; 1763 } 1764 return(bp); 1765 } 1766 1767 /* 1768 * buf_daemon: 1769 * 1770 * buffer flushing daemon. Buffers are normally flushed by the 1771 * update daemon but if it cannot keep up this process starts to 1772 * take the load in an attempt to prevent getnewbuf() from blocking. 1773 */ 1774 1775 static struct thread *bufdaemonthread; 1776 1777 static struct kproc_desc buf_kp = { 1778 "bufdaemon", 1779 buf_daemon, 1780 &bufdaemonthread 1781 }; 1782 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp) 1783 1784 static void 1785 buf_daemon() 1786 { 1787 int s; 1788 1789 /* 1790 * This process needs to be suspended prior to shutdown sync. 1791 */ 1792 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc, 1793 bufdaemonthread, SHUTDOWN_PRI_LAST); 1794 1795 /* 1796 * This process is allowed to take the buffer cache to the limit 1797 */ 1798 s = splbio(); 1799 1800 for (;;) { 1801 kproc_suspend_loop(); 1802 1803 /* 1804 * Do the flush. Limit the amount of in-transit I/O we 1805 * allow to build up, otherwise we would completely saturate 1806 * the I/O system. Wakeup any waiting processes before we 1807 * normally would so they can run in parallel with our drain. 1808 */ 1809 while (numdirtybuffers > lodirtybuffers) { 1810 if (flushbufqueues() == 0) 1811 break; 1812 waitrunningbufspace(); 1813 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 1814 } 1815 1816 /* 1817 * Only clear bd_request if we have reached our low water 1818 * mark. The buf_daemon normally waits 5 seconds and 1819 * then incrementally flushes any dirty buffers that have 1820 * built up, within reason. 1821 * 1822 * If we were unable to hit our low water mark and couldn't 1823 * find any flushable buffers, we sleep half a second. 1824 * Otherwise we loop immediately. 1825 */ 1826 if (numdirtybuffers <= lodirtybuffers) { 1827 /* 1828 * We reached our low water mark, reset the 1829 * request and sleep until we are needed again. 1830 * The sleep is just so the suspend code works. 1831 */ 1832 bd_request = 0; 1833 tsleep(&bd_request, 0, "psleep", hz); 1834 } else { 1835 /* 1836 * We couldn't find any flushable dirty buffers but 1837 * still have too many dirty buffers, we 1838 * have to sleep and try again. (rare) 1839 */ 1840 tsleep(&bd_request, 0, "qsleep", hz / 2); 1841 } 1842 } 1843 } 1844 1845 /* 1846 * flushbufqueues: 1847 * 1848 * Try to flush a buffer in the dirty queue. We must be careful to 1849 * free up B_INVAL buffers instead of write them, which NFS is 1850 * particularly sensitive to. 1851 */ 1852 1853 static int 1854 flushbufqueues(void) 1855 { 1856 struct buf *bp; 1857 int r = 0; 1858 1859 bp = TAILQ_FIRST(&bufqueues[QUEUE_DIRTY]); 1860 1861 while (bp) { 1862 KASSERT((bp->b_flags & B_DELWRI), ("unexpected clean buffer %p", bp)); 1863 if ((bp->b_flags & B_DELWRI) != 0 && 1864 (bp->b_xflags & BX_BKGRDINPROG) == 0) { 1865 if (bp->b_flags & B_INVAL) { 1866 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) 1867 panic("flushbufqueues: locked buf"); 1868 bremfree(bp); 1869 brelse(bp); 1870 ++r; 1871 break; 1872 } 1873 if (LIST_FIRST(&bp->b_dep) != NULL && 1874 bioops.io_countdeps && 1875 (bp->b_flags & B_DEFERRED) == 0 && 1876 (*bioops.io_countdeps)(bp, 0)) { 1877 TAILQ_REMOVE(&bufqueues[QUEUE_DIRTY], 1878 bp, b_freelist); 1879 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], 1880 bp, b_freelist); 1881 bp->b_flags |= B_DEFERRED; 1882 bp = TAILQ_FIRST(&bufqueues[QUEUE_DIRTY]); 1883 continue; 1884 } 1885 vfs_bio_awrite(bp); 1886 ++r; 1887 break; 1888 } 1889 bp = TAILQ_NEXT(bp, b_freelist); 1890 } 1891 return (r); 1892 } 1893 1894 /* 1895 * Check to see if a block is currently memory resident. 1896 */ 1897 struct buf * 1898 incore(struct vnode * vp, daddr_t blkno) 1899 { 1900 struct buf *bp; 1901 1902 int s = splbio(); 1903 bp = gbincore(vp, blkno); 1904 splx(s); 1905 return (bp); 1906 } 1907 1908 /* 1909 * Returns true if no I/O is needed to access the 1910 * associated VM object. This is like incore except 1911 * it also hunts around in the VM system for the data. 1912 */ 1913 1914 int 1915 inmem(struct vnode * vp, daddr_t blkno) 1916 { 1917 vm_object_t obj; 1918 vm_offset_t toff, tinc, size; 1919 vm_page_t m; 1920 vm_ooffset_t off; 1921 1922 if (incore(vp, blkno)) 1923 return 1; 1924 if (vp->v_mount == NULL) 1925 return 0; 1926 if (VOP_GETVOBJECT(vp, &obj) != 0 || (vp->v_flag & VOBJBUF) == 0) 1927 return 0; 1928 1929 size = PAGE_SIZE; 1930 if (size > vp->v_mount->mnt_stat.f_iosize) 1931 size = vp->v_mount->mnt_stat.f_iosize; 1932 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 1933 1934 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 1935 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 1936 if (!m) 1937 return 0; 1938 tinc = size; 1939 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 1940 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 1941 if (vm_page_is_valid(m, 1942 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 1943 return 0; 1944 } 1945 return 1; 1946 } 1947 1948 /* 1949 * vfs_setdirty: 1950 * 1951 * Sets the dirty range for a buffer based on the status of the dirty 1952 * bits in the pages comprising the buffer. 1953 * 1954 * The range is limited to the size of the buffer. 1955 * 1956 * This routine is primarily used by NFS, but is generalized for the 1957 * B_VMIO case. 1958 */ 1959 static void 1960 vfs_setdirty(struct buf *bp) 1961 { 1962 int i; 1963 vm_object_t object; 1964 1965 /* 1966 * Degenerate case - empty buffer 1967 */ 1968 1969 if (bp->b_bufsize == 0) 1970 return; 1971 1972 /* 1973 * We qualify the scan for modified pages on whether the 1974 * object has been flushed yet. The OBJ_WRITEABLE flag 1975 * is not cleared simply by protecting pages off. 1976 */ 1977 1978 if ((bp->b_flags & B_VMIO) == 0) 1979 return; 1980 1981 object = bp->b_pages[0]->object; 1982 1983 if ((object->flags & OBJ_WRITEABLE) && !(object->flags & OBJ_MIGHTBEDIRTY)) 1984 printf("Warning: object %p writeable but not mightbedirty\n", object); 1985 if (!(object->flags & OBJ_WRITEABLE) && (object->flags & OBJ_MIGHTBEDIRTY)) 1986 printf("Warning: object %p mightbedirty but not writeable\n", object); 1987 1988 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) { 1989 vm_offset_t boffset; 1990 vm_offset_t eoffset; 1991 1992 /* 1993 * test the pages to see if they have been modified directly 1994 * by users through the VM system. 1995 */ 1996 for (i = 0; i < bp->b_npages; i++) { 1997 vm_page_flag_clear(bp->b_pages[i], PG_ZERO); 1998 vm_page_test_dirty(bp->b_pages[i]); 1999 } 2000 2001 /* 2002 * Calculate the encompassing dirty range, boffset and eoffset, 2003 * (eoffset - boffset) bytes. 2004 */ 2005 2006 for (i = 0; i < bp->b_npages; i++) { 2007 if (bp->b_pages[i]->dirty) 2008 break; 2009 } 2010 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2011 2012 for (i = bp->b_npages - 1; i >= 0; --i) { 2013 if (bp->b_pages[i]->dirty) { 2014 break; 2015 } 2016 } 2017 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2018 2019 /* 2020 * Fit it to the buffer. 2021 */ 2022 2023 if (eoffset > bp->b_bcount) 2024 eoffset = bp->b_bcount; 2025 2026 /* 2027 * If we have a good dirty range, merge with the existing 2028 * dirty range. 2029 */ 2030 2031 if (boffset < eoffset) { 2032 if (bp->b_dirtyoff > boffset) 2033 bp->b_dirtyoff = boffset; 2034 if (bp->b_dirtyend < eoffset) 2035 bp->b_dirtyend = eoffset; 2036 } 2037 } 2038 } 2039 2040 /* 2041 * getblk: 2042 * 2043 * Get a block given a specified block and offset into a file/device. 2044 * The buffers B_DONE bit will be cleared on return, making it almost 2045 * ready for an I/O initiation. B_INVAL may or may not be set on 2046 * return. The caller should clear B_INVAL prior to initiating a 2047 * READ. 2048 * 2049 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2050 * an existing buffer. 2051 * 2052 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2053 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2054 * and then cleared based on the backing VM. If the previous buffer is 2055 * non-0-sized but invalid, B_CACHE will be cleared. 2056 * 2057 * If getblk() must create a new buffer, the new buffer is returned with 2058 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2059 * case it is returned with B_INVAL clear and B_CACHE set based on the 2060 * backing VM. 2061 * 2062 * getblk() also forces a VOP_BWRITE() for any B_DELWRI buffer whos 2063 * B_CACHE bit is clear. 2064 * 2065 * What this means, basically, is that the caller should use B_CACHE to 2066 * determine whether the buffer is fully valid or not and should clear 2067 * B_INVAL prior to issuing a read. If the caller intends to validate 2068 * the buffer by loading its data area with something, the caller needs 2069 * to clear B_INVAL. If the caller does this without issuing an I/O, 2070 * the caller should set B_CACHE ( as an optimization ), else the caller 2071 * should issue the I/O and biodone() will set B_CACHE if the I/O was 2072 * a write attempt or if it was a successfull read. If the caller 2073 * intends to issue a READ, the caller must clear B_INVAL and B_ERROR 2074 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 2075 */ 2076 struct buf * 2077 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo) 2078 { 2079 struct buf *bp; 2080 int s; 2081 struct bufhashhdr *bh; 2082 2083 if (size > MAXBSIZE) 2084 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 2085 2086 s = splbio(); 2087 loop: 2088 /* 2089 * Block if we are low on buffers. Certain processes are allowed 2090 * to completely exhaust the buffer cache. 2091 * 2092 * If this check ever becomes a bottleneck it may be better to 2093 * move it into the else, when gbincore() fails. At the moment 2094 * it isn't a problem. 2095 * 2096 * XXX remove, we cannot afford to block anywhere if holding a vnode 2097 * lock in low-memory situation, so take it to the max. 2098 */ 2099 if (numfreebuffers == 0) { 2100 if (!curproc) 2101 return NULL; 2102 needsbuffer |= VFS_BIO_NEED_ANY; 2103 tsleep(&needsbuffer, slpflag, "newbuf", slptimeo); 2104 } 2105 2106 if ((bp = gbincore(vp, blkno))) { 2107 /* 2108 * Buffer is in-core. If the buffer is not busy, it must 2109 * be on a queue. 2110 */ 2111 2112 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) { 2113 if (BUF_TIMELOCK(bp, LK_EXCLUSIVE | LK_SLEEPFAIL, 2114 "getblk", slpflag, slptimeo) == ENOLCK) 2115 goto loop; 2116 splx(s); 2117 return (struct buf *) NULL; 2118 } 2119 2120 /* 2121 * The buffer is locked. B_CACHE is cleared if the buffer is 2122 * invalid. Ohterwise, for a non-VMIO buffer, B_CACHE is set 2123 * and for a VMIO buffer B_CACHE is adjusted according to the 2124 * backing VM cache. 2125 */ 2126 if (bp->b_flags & B_INVAL) 2127 bp->b_flags &= ~B_CACHE; 2128 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 2129 bp->b_flags |= B_CACHE; 2130 bremfree(bp); 2131 2132 /* 2133 * check for size inconsistancies for non-VMIO case. 2134 */ 2135 2136 if (bp->b_bcount != size) { 2137 if ((bp->b_flags & B_VMIO) == 0 || 2138 (size > bp->b_kvasize)) { 2139 if (bp->b_flags & B_DELWRI) { 2140 bp->b_flags |= B_NOCACHE; 2141 VOP_BWRITE(bp->b_vp, bp); 2142 } else { 2143 if ((bp->b_flags & B_VMIO) && 2144 (LIST_FIRST(&bp->b_dep) == NULL)) { 2145 bp->b_flags |= B_RELBUF; 2146 brelse(bp); 2147 } else { 2148 bp->b_flags |= B_NOCACHE; 2149 VOP_BWRITE(bp->b_vp, bp); 2150 } 2151 } 2152 goto loop; 2153 } 2154 } 2155 2156 /* 2157 * If the size is inconsistant in the VMIO case, we can resize 2158 * the buffer. This might lead to B_CACHE getting set or 2159 * cleared. If the size has not changed, B_CACHE remains 2160 * unchanged from its previous state. 2161 */ 2162 2163 if (bp->b_bcount != size) 2164 allocbuf(bp, size); 2165 2166 KASSERT(bp->b_offset != NOOFFSET, 2167 ("getblk: no buffer offset")); 2168 2169 /* 2170 * A buffer with B_DELWRI set and B_CACHE clear must 2171 * be committed before we can return the buffer in 2172 * order to prevent the caller from issuing a read 2173 * ( due to B_CACHE not being set ) and overwriting 2174 * it. 2175 * 2176 * Most callers, including NFS and FFS, need this to 2177 * operate properly either because they assume they 2178 * can issue a read if B_CACHE is not set, or because 2179 * ( for example ) an uncached B_DELWRI might loop due 2180 * to softupdates re-dirtying the buffer. In the latter 2181 * case, B_CACHE is set after the first write completes, 2182 * preventing further loops. 2183 * 2184 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 2185 * above while extending the buffer, we cannot allow the 2186 * buffer to remain with B_CACHE set after the write 2187 * completes or it will represent a corrupt state. To 2188 * deal with this we set B_NOCACHE to scrap the buffer 2189 * after the write. 2190 * 2191 * We might be able to do something fancy, like setting 2192 * B_CACHE in bwrite() except if B_DELWRI is already set, 2193 * so the below call doesn't set B_CACHE, but that gets real 2194 * confusing. This is much easier. 2195 */ 2196 2197 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 2198 bp->b_flags |= B_NOCACHE; 2199 VOP_BWRITE(bp->b_vp, bp); 2200 goto loop; 2201 } 2202 2203 splx(s); 2204 bp->b_flags &= ~B_DONE; 2205 } else { 2206 /* 2207 * Buffer is not in-core, create new buffer. The buffer 2208 * returned by getnewbuf() is locked. Note that the returned 2209 * buffer is also considered valid (not marked B_INVAL). 2210 */ 2211 int bsize, maxsize, vmio; 2212 off_t offset; 2213 2214 if (vn_isdisk(vp, NULL)) 2215 bsize = DEV_BSIZE; 2216 else if (vp->v_mountedhere) 2217 bsize = vp->v_mountedhere->mnt_stat.f_iosize; 2218 else if (vp->v_mount) 2219 bsize = vp->v_mount->mnt_stat.f_iosize; 2220 else 2221 bsize = size; 2222 2223 offset = (off_t)blkno * bsize; 2224 vmio = (VOP_GETVOBJECT(vp, NULL) == 0) && (vp->v_flag & VOBJBUF); 2225 maxsize = vmio ? size + (offset & PAGE_MASK) : size; 2226 maxsize = imax(maxsize, bsize); 2227 2228 if ((bp = getnewbuf(slpflag, slptimeo, size, maxsize)) == NULL) { 2229 if (slpflag || slptimeo) { 2230 splx(s); 2231 return NULL; 2232 } 2233 goto loop; 2234 } 2235 2236 /* 2237 * This code is used to make sure that a buffer is not 2238 * created while the getnewbuf routine is blocked. 2239 * This can be a problem whether the vnode is locked or not. 2240 * If the buffer is created out from under us, we have to 2241 * throw away the one we just created. There is now window 2242 * race because we are safely running at splbio() from the 2243 * point of the duplicate buffer creation through to here, 2244 * and we've locked the buffer. 2245 */ 2246 if (gbincore(vp, blkno)) { 2247 bp->b_flags |= B_INVAL; 2248 brelse(bp); 2249 goto loop; 2250 } 2251 2252 /* 2253 * Insert the buffer into the hash, so that it can 2254 * be found by incore. 2255 */ 2256 bp->b_blkno = bp->b_lblkno = blkno; 2257 bp->b_offset = offset; 2258 2259 bgetvp(vp, bp); 2260 LIST_REMOVE(bp, b_hash); 2261 bh = bufhash(vp, blkno); 2262 LIST_INSERT_HEAD(bh, bp, b_hash); 2263 2264 /* 2265 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 2266 * buffer size starts out as 0, B_CACHE will be set by 2267 * allocbuf() for the VMIO case prior to it testing the 2268 * backing store for validity. 2269 */ 2270 2271 if (vmio) { 2272 bp->b_flags |= B_VMIO; 2273 #if defined(VFS_BIO_DEBUG) 2274 if (vp->v_type != VREG && vp->v_type != VBLK) 2275 printf("getblk: vmioing file type %d???\n", vp->v_type); 2276 #endif 2277 } else { 2278 bp->b_flags &= ~B_VMIO; 2279 } 2280 2281 allocbuf(bp, size); 2282 2283 splx(s); 2284 bp->b_flags &= ~B_DONE; 2285 } 2286 return (bp); 2287 } 2288 2289 /* 2290 * Get an empty, disassociated buffer of given size. The buffer is initially 2291 * set to B_INVAL. 2292 */ 2293 struct buf * 2294 geteblk(int size) 2295 { 2296 struct buf *bp; 2297 int s; 2298 int maxsize; 2299 2300 maxsize = (size + BKVAMASK) & ~BKVAMASK; 2301 2302 s = splbio(); 2303 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0); 2304 splx(s); 2305 allocbuf(bp, size); 2306 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 2307 return (bp); 2308 } 2309 2310 2311 /* 2312 * This code constitutes the buffer memory from either anonymous system 2313 * memory (in the case of non-VMIO operations) or from an associated 2314 * VM object (in the case of VMIO operations). This code is able to 2315 * resize a buffer up or down. 2316 * 2317 * Note that this code is tricky, and has many complications to resolve 2318 * deadlock or inconsistant data situations. Tread lightly!!! 2319 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 2320 * the caller. Calling this code willy nilly can result in the loss of data. 2321 * 2322 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 2323 * B_CACHE for the non-VMIO case. 2324 */ 2325 2326 int 2327 allocbuf(struct buf *bp, int size) 2328 { 2329 int newbsize, mbsize; 2330 int i; 2331 2332 if (BUF_REFCNT(bp) == 0) 2333 panic("allocbuf: buffer not busy"); 2334 2335 if (bp->b_kvasize < size) 2336 panic("allocbuf: buffer too small"); 2337 2338 if ((bp->b_flags & B_VMIO) == 0) { 2339 caddr_t origbuf; 2340 int origbufsize; 2341 /* 2342 * Just get anonymous memory from the kernel. Don't 2343 * mess with B_CACHE. 2344 */ 2345 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2346 #if !defined(NO_B_MALLOC) 2347 if (bp->b_flags & B_MALLOC) 2348 newbsize = mbsize; 2349 else 2350 #endif 2351 newbsize = round_page(size); 2352 2353 if (newbsize < bp->b_bufsize) { 2354 #if !defined(NO_B_MALLOC) 2355 /* 2356 * malloced buffers are not shrunk 2357 */ 2358 if (bp->b_flags & B_MALLOC) { 2359 if (newbsize) { 2360 bp->b_bcount = size; 2361 } else { 2362 free(bp->b_data, M_BIOBUF); 2363 if (bp->b_bufsize) { 2364 bufmallocspace -= bp->b_bufsize; 2365 bufspacewakeup(); 2366 bp->b_bufsize = 0; 2367 } 2368 bp->b_data = bp->b_kvabase; 2369 bp->b_bcount = 0; 2370 bp->b_flags &= ~B_MALLOC; 2371 } 2372 return 1; 2373 } 2374 #endif 2375 vm_hold_free_pages( 2376 bp, 2377 (vm_offset_t) bp->b_data + newbsize, 2378 (vm_offset_t) bp->b_data + bp->b_bufsize); 2379 } else if (newbsize > bp->b_bufsize) { 2380 #if !defined(NO_B_MALLOC) 2381 /* 2382 * We only use malloced memory on the first allocation. 2383 * and revert to page-allocated memory when the buffer 2384 * grows. 2385 */ 2386 if ( (bufmallocspace < maxbufmallocspace) && 2387 (bp->b_bufsize == 0) && 2388 (mbsize <= PAGE_SIZE/2)) { 2389 2390 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 2391 bp->b_bufsize = mbsize; 2392 bp->b_bcount = size; 2393 bp->b_flags |= B_MALLOC; 2394 bufmallocspace += mbsize; 2395 return 1; 2396 } 2397 #endif 2398 origbuf = NULL; 2399 origbufsize = 0; 2400 #if !defined(NO_B_MALLOC) 2401 /* 2402 * If the buffer is growing on its other-than-first allocation, 2403 * then we revert to the page-allocation scheme. 2404 */ 2405 if (bp->b_flags & B_MALLOC) { 2406 origbuf = bp->b_data; 2407 origbufsize = bp->b_bufsize; 2408 bp->b_data = bp->b_kvabase; 2409 if (bp->b_bufsize) { 2410 bufmallocspace -= bp->b_bufsize; 2411 bufspacewakeup(); 2412 bp->b_bufsize = 0; 2413 } 2414 bp->b_flags &= ~B_MALLOC; 2415 newbsize = round_page(newbsize); 2416 } 2417 #endif 2418 vm_hold_load_pages( 2419 bp, 2420 (vm_offset_t) bp->b_data + bp->b_bufsize, 2421 (vm_offset_t) bp->b_data + newbsize); 2422 #if !defined(NO_B_MALLOC) 2423 if (origbuf) { 2424 bcopy(origbuf, bp->b_data, origbufsize); 2425 free(origbuf, M_BIOBUF); 2426 } 2427 #endif 2428 } 2429 } else { 2430 vm_page_t m; 2431 int desiredpages; 2432 2433 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2434 desiredpages = (size == 0) ? 0 : 2435 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 2436 2437 #if !defined(NO_B_MALLOC) 2438 if (bp->b_flags & B_MALLOC) 2439 panic("allocbuf: VMIO buffer can't be malloced"); 2440 #endif 2441 /* 2442 * Set B_CACHE initially if buffer is 0 length or will become 2443 * 0-length. 2444 */ 2445 if (size == 0 || bp->b_bufsize == 0) 2446 bp->b_flags |= B_CACHE; 2447 2448 if (newbsize < bp->b_bufsize) { 2449 /* 2450 * DEV_BSIZE aligned new buffer size is less then the 2451 * DEV_BSIZE aligned existing buffer size. Figure out 2452 * if we have to remove any pages. 2453 */ 2454 if (desiredpages < bp->b_npages) { 2455 for (i = desiredpages; i < bp->b_npages; i++) { 2456 /* 2457 * the page is not freed here -- it 2458 * is the responsibility of 2459 * vnode_pager_setsize 2460 */ 2461 m = bp->b_pages[i]; 2462 KASSERT(m != bogus_page, 2463 ("allocbuf: bogus page found")); 2464 while (vm_page_sleep_busy(m, TRUE, "biodep")) 2465 ; 2466 2467 bp->b_pages[i] = NULL; 2468 vm_page_unwire(m, 0); 2469 } 2470 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) + 2471 (desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages)); 2472 bp->b_npages = desiredpages; 2473 } 2474 } else if (size > bp->b_bcount) { 2475 /* 2476 * We are growing the buffer, possibly in a 2477 * byte-granular fashion. 2478 */ 2479 struct vnode *vp; 2480 vm_object_t obj; 2481 vm_offset_t toff; 2482 vm_offset_t tinc; 2483 2484 /* 2485 * Step 1, bring in the VM pages from the object, 2486 * allocating them if necessary. We must clear 2487 * B_CACHE if these pages are not valid for the 2488 * range covered by the buffer. 2489 */ 2490 2491 vp = bp->b_vp; 2492 VOP_GETVOBJECT(vp, &obj); 2493 2494 while (bp->b_npages < desiredpages) { 2495 vm_page_t m; 2496 vm_pindex_t pi; 2497 2498 pi = OFF_TO_IDX(bp->b_offset) + bp->b_npages; 2499 if ((m = vm_page_lookup(obj, pi)) == NULL) { 2500 /* 2501 * note: must allocate system pages 2502 * since blocking here could intefere 2503 * with paging I/O, no matter which 2504 * process we are. 2505 */ 2506 m = vm_page_alloc(obj, pi, VM_ALLOC_NORMAL | VM_ALLOC_SYSTEM); 2507 if (m == NULL) { 2508 VM_WAIT; 2509 vm_pageout_deficit += desiredpages - bp->b_npages; 2510 } else { 2511 vm_page_wire(m); 2512 vm_page_wakeup(m); 2513 bp->b_flags &= ~B_CACHE; 2514 bp->b_pages[bp->b_npages] = m; 2515 ++bp->b_npages; 2516 } 2517 continue; 2518 } 2519 2520 /* 2521 * We found a page. If we have to sleep on it, 2522 * retry because it might have gotten freed out 2523 * from under us. 2524 * 2525 * We can only test PG_BUSY here. Blocking on 2526 * m->busy might lead to a deadlock: 2527 * 2528 * vm_fault->getpages->cluster_read->allocbuf 2529 * 2530 */ 2531 2532 if (vm_page_sleep_busy(m, FALSE, "pgtblk")) 2533 continue; 2534 2535 /* 2536 * We have a good page. Should we wakeup the 2537 * page daemon? 2538 */ 2539 if ((curthread != pagethread) && 2540 ((m->queue - m->pc) == PQ_CACHE) && 2541 ((vmstats.v_free_count + vmstats.v_cache_count) < 2542 (vmstats.v_free_min + vmstats.v_cache_min))) { 2543 pagedaemon_wakeup(); 2544 } 2545 vm_page_flag_clear(m, PG_ZERO); 2546 vm_page_wire(m); 2547 bp->b_pages[bp->b_npages] = m; 2548 ++bp->b_npages; 2549 } 2550 2551 /* 2552 * Step 2. We've loaded the pages into the buffer, 2553 * we have to figure out if we can still have B_CACHE 2554 * set. Note that B_CACHE is set according to the 2555 * byte-granular range ( bcount and size ), new the 2556 * aligned range ( newbsize ). 2557 * 2558 * The VM test is against m->valid, which is DEV_BSIZE 2559 * aligned. Needless to say, the validity of the data 2560 * needs to also be DEV_BSIZE aligned. Note that this 2561 * fails with NFS if the server or some other client 2562 * extends the file's EOF. If our buffer is resized, 2563 * B_CACHE may remain set! XXX 2564 */ 2565 2566 toff = bp->b_bcount; 2567 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 2568 2569 while ((bp->b_flags & B_CACHE) && toff < size) { 2570 vm_pindex_t pi; 2571 2572 if (tinc > (size - toff)) 2573 tinc = size - toff; 2574 2575 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 2576 PAGE_SHIFT; 2577 2578 vfs_buf_test_cache( 2579 bp, 2580 bp->b_offset, 2581 toff, 2582 tinc, 2583 bp->b_pages[pi] 2584 ); 2585 toff += tinc; 2586 tinc = PAGE_SIZE; 2587 } 2588 2589 /* 2590 * Step 3, fixup the KVM pmap. Remember that 2591 * bp->b_data is relative to bp->b_offset, but 2592 * bp->b_offset may be offset into the first page. 2593 */ 2594 2595 bp->b_data = (caddr_t) 2596 trunc_page((vm_offset_t)bp->b_data); 2597 pmap_qenter( 2598 (vm_offset_t)bp->b_data, 2599 bp->b_pages, 2600 bp->b_npages 2601 ); 2602 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 2603 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 2604 } 2605 } 2606 if (newbsize < bp->b_bufsize) 2607 bufspacewakeup(); 2608 bp->b_bufsize = newbsize; /* actual buffer allocation */ 2609 bp->b_bcount = size; /* requested buffer size */ 2610 return 1; 2611 } 2612 2613 /* 2614 * biowait: 2615 * 2616 * Wait for buffer I/O completion, returning error status. The buffer 2617 * is left locked and B_DONE on return. B_EINTR is converted into a EINTR 2618 * error and cleared. 2619 */ 2620 int 2621 biowait(struct buf * bp) 2622 { 2623 int s; 2624 2625 s = splbio(); 2626 while ((bp->b_flags & B_DONE) == 0) { 2627 #if defined(NO_SCHEDULE_MODS) 2628 tsleep(bp, 0, "biowait", 0); 2629 #else 2630 if (bp->b_flags & B_READ) 2631 tsleep(bp, 0, "biord", 0); 2632 else 2633 tsleep(bp, 0, "biowr", 0); 2634 #endif 2635 } 2636 splx(s); 2637 if (bp->b_flags & B_EINTR) { 2638 bp->b_flags &= ~B_EINTR; 2639 return (EINTR); 2640 } 2641 if (bp->b_flags & B_ERROR) { 2642 return (bp->b_error ? bp->b_error : EIO); 2643 } else { 2644 return (0); 2645 } 2646 } 2647 2648 /* 2649 * biodone: 2650 * 2651 * Finish I/O on a buffer, optionally calling a completion function. 2652 * This is usually called from an interrupt so process blocking is 2653 * not allowed. 2654 * 2655 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 2656 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 2657 * assuming B_INVAL is clear. 2658 * 2659 * For the VMIO case, we set B_CACHE if the op was a read and no 2660 * read error occured, or if the op was a write. B_CACHE is never 2661 * set if the buffer is invalid or otherwise uncacheable. 2662 * 2663 * biodone does not mess with B_INVAL, allowing the I/O routine or the 2664 * initiator to leave B_INVAL set to brelse the buffer out of existance 2665 * in the biodone routine. 2666 */ 2667 void 2668 biodone(struct buf * bp) 2669 { 2670 int s, error; 2671 2672 s = splbio(); 2673 2674 KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp, BUF_REFCNT(bp))); 2675 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 2676 2677 bp->b_flags |= B_DONE; 2678 runningbufwakeup(bp); 2679 2680 if (bp->b_flags & B_FREEBUF) { 2681 brelse(bp); 2682 splx(s); 2683 return; 2684 } 2685 2686 if ((bp->b_flags & B_READ) == 0) { 2687 vwakeup(bp); 2688 } 2689 2690 /* call optional completion function if requested */ 2691 if (bp->b_flags & B_CALL) { 2692 bp->b_flags &= ~B_CALL; 2693 (*bp->b_iodone) (bp); 2694 splx(s); 2695 return; 2696 } 2697 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_complete) 2698 (*bioops.io_complete)(bp); 2699 2700 if (bp->b_flags & B_VMIO) { 2701 int i; 2702 vm_ooffset_t foff; 2703 vm_page_t m; 2704 vm_object_t obj; 2705 int iosize; 2706 struct vnode *vp = bp->b_vp; 2707 2708 error = VOP_GETVOBJECT(vp, &obj); 2709 2710 #if defined(VFS_BIO_DEBUG) 2711 if (vp->v_usecount == 0) { 2712 panic("biodone: zero vnode ref count"); 2713 } 2714 2715 if (error) { 2716 panic("biodone: missing VM object"); 2717 } 2718 2719 if ((vp->v_flag & VOBJBUF) == 0) { 2720 panic("biodone: vnode is not setup for merged cache"); 2721 } 2722 #endif 2723 2724 foff = bp->b_offset; 2725 KASSERT(bp->b_offset != NOOFFSET, 2726 ("biodone: no buffer offset")); 2727 2728 if (error) { 2729 panic("biodone: no object"); 2730 } 2731 #if defined(VFS_BIO_DEBUG) 2732 if (obj->paging_in_progress < bp->b_npages) { 2733 printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n", 2734 obj->paging_in_progress, bp->b_npages); 2735 } 2736 #endif 2737 2738 /* 2739 * Set B_CACHE if the op was a normal read and no error 2740 * occured. B_CACHE is set for writes in the b*write() 2741 * routines. 2742 */ 2743 iosize = bp->b_bcount - bp->b_resid; 2744 if ((bp->b_flags & (B_READ|B_FREEBUF|B_INVAL|B_NOCACHE|B_ERROR)) == B_READ) { 2745 bp->b_flags |= B_CACHE; 2746 } 2747 2748 for (i = 0; i < bp->b_npages; i++) { 2749 int bogusflag = 0; 2750 int resid; 2751 2752 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 2753 if (resid > iosize) 2754 resid = iosize; 2755 2756 /* 2757 * cleanup bogus pages, restoring the originals 2758 */ 2759 m = bp->b_pages[i]; 2760 if (m == bogus_page) { 2761 bogusflag = 1; 2762 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 2763 if (m == NULL) 2764 panic("biodone: page disappeared"); 2765 bp->b_pages[i] = m; 2766 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 2767 } 2768 #if defined(VFS_BIO_DEBUG) 2769 if (OFF_TO_IDX(foff) != m->pindex) { 2770 printf( 2771 "biodone: foff(%lu)/m->pindex(%d) mismatch\n", 2772 (unsigned long)foff, m->pindex); 2773 } 2774 #endif 2775 2776 /* 2777 * In the write case, the valid and clean bits are 2778 * already changed correctly ( see bdwrite() ), so we 2779 * only need to do this here in the read case. 2780 */ 2781 if ((bp->b_flags & B_READ) && !bogusflag && resid > 0) { 2782 vfs_page_set_valid(bp, foff, i, m); 2783 } 2784 vm_page_flag_clear(m, PG_ZERO); 2785 2786 /* 2787 * when debugging new filesystems or buffer I/O methods, this 2788 * is the most common error that pops up. if you see this, you 2789 * have not set the page busy flag correctly!!! 2790 */ 2791 if (m->busy == 0) { 2792 printf("biodone: page busy < 0, " 2793 "pindex: %d, foff: 0x(%x,%x), " 2794 "resid: %d, index: %d\n", 2795 (int) m->pindex, (int)(foff >> 32), 2796 (int) foff & 0xffffffff, resid, i); 2797 if (!vn_isdisk(vp, NULL)) 2798 printf(" iosize: %ld, lblkno: %d, flags: 0x%lx, npages: %d\n", 2799 bp->b_vp->v_mount->mnt_stat.f_iosize, 2800 (int) bp->b_lblkno, 2801 bp->b_flags, bp->b_npages); 2802 else 2803 printf(" VDEV, lblkno: %d, flags: 0x%lx, npages: %d\n", 2804 (int) bp->b_lblkno, 2805 bp->b_flags, bp->b_npages); 2806 printf(" valid: 0x%x, dirty: 0x%x, wired: %d\n", 2807 m->valid, m->dirty, m->wire_count); 2808 panic("biodone: page busy < 0\n"); 2809 } 2810 vm_page_io_finish(m); 2811 vm_object_pip_subtract(obj, 1); 2812 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2813 iosize -= resid; 2814 } 2815 if (obj) 2816 vm_object_pip_wakeupn(obj, 0); 2817 } 2818 2819 /* 2820 * For asynchronous completions, release the buffer now. The brelse 2821 * will do a wakeup there if necessary - so no need to do a wakeup 2822 * here in the async case. The sync case always needs to do a wakeup. 2823 */ 2824 2825 if (bp->b_flags & B_ASYNC) { 2826 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR | B_RELBUF)) != 0) 2827 brelse(bp); 2828 else 2829 bqrelse(bp); 2830 } else { 2831 wakeup(bp); 2832 } 2833 splx(s); 2834 } 2835 2836 /* 2837 * This routine is called in lieu of iodone in the case of 2838 * incomplete I/O. This keeps the busy status for pages 2839 * consistant. 2840 */ 2841 void 2842 vfs_unbusy_pages(struct buf * bp) 2843 { 2844 int i; 2845 2846 runningbufwakeup(bp); 2847 if (bp->b_flags & B_VMIO) { 2848 struct vnode *vp = bp->b_vp; 2849 vm_object_t obj; 2850 2851 VOP_GETVOBJECT(vp, &obj); 2852 2853 for (i = 0; i < bp->b_npages; i++) { 2854 vm_page_t m = bp->b_pages[i]; 2855 2856 if (m == bogus_page) { 2857 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 2858 if (!m) { 2859 panic("vfs_unbusy_pages: page missing\n"); 2860 } 2861 bp->b_pages[i] = m; 2862 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 2863 } 2864 vm_object_pip_subtract(obj, 1); 2865 vm_page_flag_clear(m, PG_ZERO); 2866 vm_page_io_finish(m); 2867 } 2868 vm_object_pip_wakeupn(obj, 0); 2869 } 2870 } 2871 2872 /* 2873 * vfs_page_set_valid: 2874 * 2875 * Set the valid bits in a page based on the supplied offset. The 2876 * range is restricted to the buffer's size. 2877 * 2878 * This routine is typically called after a read completes. 2879 */ 2880 static void 2881 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m) 2882 { 2883 vm_ooffset_t soff, eoff; 2884 2885 /* 2886 * Start and end offsets in buffer. eoff - soff may not cross a 2887 * page boundry or cross the end of the buffer. The end of the 2888 * buffer, in this case, is our file EOF, not the allocation size 2889 * of the buffer. 2890 */ 2891 soff = off; 2892 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2893 if (eoff > bp->b_offset + bp->b_bcount) 2894 eoff = bp->b_offset + bp->b_bcount; 2895 2896 /* 2897 * Set valid range. This is typically the entire buffer and thus the 2898 * entire page. 2899 */ 2900 if (eoff > soff) { 2901 vm_page_set_validclean( 2902 m, 2903 (vm_offset_t) (soff & PAGE_MASK), 2904 (vm_offset_t) (eoff - soff) 2905 ); 2906 } 2907 } 2908 2909 /* 2910 * This routine is called before a device strategy routine. 2911 * It is used to tell the VM system that paging I/O is in 2912 * progress, and treat the pages associated with the buffer 2913 * almost as being PG_BUSY. Also the object paging_in_progress 2914 * flag is handled to make sure that the object doesn't become 2915 * inconsistant. 2916 * 2917 * Since I/O has not been initiated yet, certain buffer flags 2918 * such as B_ERROR or B_INVAL may be in an inconsistant state 2919 * and should be ignored. 2920 */ 2921 void 2922 vfs_busy_pages(struct buf * bp, int clear_modify) 2923 { 2924 int i, bogus; 2925 2926 if (bp->b_flags & B_VMIO) { 2927 struct vnode *vp = bp->b_vp; 2928 vm_object_t obj; 2929 vm_ooffset_t foff; 2930 2931 VOP_GETVOBJECT(vp, &obj); 2932 foff = bp->b_offset; 2933 KASSERT(bp->b_offset != NOOFFSET, 2934 ("vfs_busy_pages: no buffer offset")); 2935 vfs_setdirty(bp); 2936 2937 retry: 2938 for (i = 0; i < bp->b_npages; i++) { 2939 vm_page_t m = bp->b_pages[i]; 2940 if (vm_page_sleep_busy(m, FALSE, "vbpage")) 2941 goto retry; 2942 } 2943 2944 bogus = 0; 2945 for (i = 0; i < bp->b_npages; i++) { 2946 vm_page_t m = bp->b_pages[i]; 2947 2948 vm_page_flag_clear(m, PG_ZERO); 2949 if ((bp->b_flags & B_CLUSTER) == 0) { 2950 vm_object_pip_add(obj, 1); 2951 vm_page_io_start(m); 2952 } 2953 2954 /* 2955 * When readying a buffer for a read ( i.e 2956 * clear_modify == 0 ), it is important to do 2957 * bogus_page replacement for valid pages in 2958 * partially instantiated buffers. Partially 2959 * instantiated buffers can, in turn, occur when 2960 * reconstituting a buffer from its VM backing store 2961 * base. We only have to do this if B_CACHE is 2962 * clear ( which causes the I/O to occur in the 2963 * first place ). The replacement prevents the read 2964 * I/O from overwriting potentially dirty VM-backed 2965 * pages. XXX bogus page replacement is, uh, bogus. 2966 * It may not work properly with small-block devices. 2967 * We need to find a better way. 2968 */ 2969 2970 vm_page_protect(m, VM_PROT_NONE); 2971 if (clear_modify) 2972 vfs_page_set_valid(bp, foff, i, m); 2973 else if (m->valid == VM_PAGE_BITS_ALL && 2974 (bp->b_flags & B_CACHE) == 0) { 2975 bp->b_pages[i] = bogus_page; 2976 bogus++; 2977 } 2978 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2979 } 2980 if (bogus) 2981 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 2982 } 2983 2984 /* 2985 * This is the easiest place to put the process accounting for the I/O 2986 * for now. 2987 */ 2988 { 2989 struct proc *p; 2990 2991 if ((p = curthread->td_proc) != NULL) { 2992 if (bp->b_flags & B_READ) 2993 p->p_stats->p_ru.ru_inblock++; 2994 else 2995 p->p_stats->p_ru.ru_oublock++; 2996 } 2997 } 2998 } 2999 3000 /* 3001 * Tell the VM system that the pages associated with this buffer 3002 * are clean. This is used for delayed writes where the data is 3003 * going to go to disk eventually without additional VM intevention. 3004 * 3005 * Note that while we only really need to clean through to b_bcount, we 3006 * just go ahead and clean through to b_bufsize. 3007 */ 3008 static void 3009 vfs_clean_pages(struct buf * bp) 3010 { 3011 int i; 3012 3013 if (bp->b_flags & B_VMIO) { 3014 vm_ooffset_t foff; 3015 3016 foff = bp->b_offset; 3017 KASSERT(bp->b_offset != NOOFFSET, 3018 ("vfs_clean_pages: no buffer offset")); 3019 for (i = 0; i < bp->b_npages; i++) { 3020 vm_page_t m = bp->b_pages[i]; 3021 vm_ooffset_t noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3022 vm_ooffset_t eoff = noff; 3023 3024 if (eoff > bp->b_offset + bp->b_bufsize) 3025 eoff = bp->b_offset + bp->b_bufsize; 3026 vfs_page_set_valid(bp, foff, i, m); 3027 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3028 foff = noff; 3029 } 3030 } 3031 } 3032 3033 /* 3034 * vfs_bio_set_validclean: 3035 * 3036 * Set the range within the buffer to valid and clean. The range is 3037 * relative to the beginning of the buffer, b_offset. Note that b_offset 3038 * itself may be offset from the beginning of the first page. 3039 */ 3040 3041 void 3042 vfs_bio_set_validclean(struct buf *bp, int base, int size) 3043 { 3044 if (bp->b_flags & B_VMIO) { 3045 int i; 3046 int n; 3047 3048 /* 3049 * Fixup base to be relative to beginning of first page. 3050 * Set initial n to be the maximum number of bytes in the 3051 * first page that can be validated. 3052 */ 3053 3054 base += (bp->b_offset & PAGE_MASK); 3055 n = PAGE_SIZE - (base & PAGE_MASK); 3056 3057 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 3058 vm_page_t m = bp->b_pages[i]; 3059 3060 if (n > size) 3061 n = size; 3062 3063 vm_page_set_validclean(m, base & PAGE_MASK, n); 3064 base += n; 3065 size -= n; 3066 n = PAGE_SIZE; 3067 } 3068 } 3069 } 3070 3071 /* 3072 * vfs_bio_clrbuf: 3073 * 3074 * clear a buffer. This routine essentially fakes an I/O, so we need 3075 * to clear B_ERROR and B_INVAL. 3076 * 3077 * Note that while we only theoretically need to clear through b_bcount, 3078 * we go ahead and clear through b_bufsize. 3079 */ 3080 3081 void 3082 vfs_bio_clrbuf(struct buf *bp) 3083 { 3084 int i, mask = 0; 3085 caddr_t sa, ea; 3086 if ((bp->b_flags & (B_VMIO | B_MALLOC)) == B_VMIO) { 3087 bp->b_flags &= ~(B_INVAL|B_ERROR); 3088 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 3089 (bp->b_offset & PAGE_MASK) == 0) { 3090 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 3091 if ((bp->b_pages[0]->valid & mask) == mask) { 3092 bp->b_resid = 0; 3093 return; 3094 } 3095 if (((bp->b_pages[0]->flags & PG_ZERO) == 0) && 3096 ((bp->b_pages[0]->valid & mask) == 0)) { 3097 bzero(bp->b_data, bp->b_bufsize); 3098 bp->b_pages[0]->valid |= mask; 3099 bp->b_resid = 0; 3100 return; 3101 } 3102 } 3103 ea = sa = bp->b_data; 3104 for(i=0;i<bp->b_npages;i++,sa=ea) { 3105 int j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; 3106 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); 3107 ea = (caddr_t)(vm_offset_t)ulmin( 3108 (u_long)(vm_offset_t)ea, 3109 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); 3110 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 3111 if ((bp->b_pages[i]->valid & mask) == mask) 3112 continue; 3113 if ((bp->b_pages[i]->valid & mask) == 0) { 3114 if ((bp->b_pages[i]->flags & PG_ZERO) == 0) { 3115 bzero(sa, ea - sa); 3116 } 3117 } else { 3118 for (; sa < ea; sa += DEV_BSIZE, j++) { 3119 if (((bp->b_pages[i]->flags & PG_ZERO) == 0) && 3120 (bp->b_pages[i]->valid & (1<<j)) == 0) 3121 bzero(sa, DEV_BSIZE); 3122 } 3123 } 3124 bp->b_pages[i]->valid |= mask; 3125 vm_page_flag_clear(bp->b_pages[i], PG_ZERO); 3126 } 3127 bp->b_resid = 0; 3128 } else { 3129 clrbuf(bp); 3130 } 3131 } 3132 3133 /* 3134 * vm_hold_load_pages and vm_hold_unload pages get pages into 3135 * a buffers address space. The pages are anonymous and are 3136 * not associated with a file object. 3137 */ 3138 void 3139 vm_hold_load_pages(struct buf * bp, vm_offset_t from, vm_offset_t to) 3140 { 3141 vm_offset_t pg; 3142 vm_page_t p; 3143 int index; 3144 3145 to = round_page(to); 3146 from = round_page(from); 3147 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3148 3149 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3150 3151 tryagain: 3152 3153 /* 3154 * note: must allocate system pages since blocking here 3155 * could intefere with paging I/O, no matter which 3156 * process we are. 3157 */ 3158 p = vm_page_alloc(kernel_object, 3159 ((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 3160 VM_ALLOC_NORMAL | VM_ALLOC_SYSTEM); 3161 if (!p) { 3162 vm_pageout_deficit += (to - from) >> PAGE_SHIFT; 3163 VM_WAIT; 3164 goto tryagain; 3165 } 3166 vm_page_wire(p); 3167 p->valid = VM_PAGE_BITS_ALL; 3168 vm_page_flag_clear(p, PG_ZERO); 3169 pmap_kenter(pg, VM_PAGE_TO_PHYS(p)); 3170 bp->b_pages[index] = p; 3171 vm_page_wakeup(p); 3172 } 3173 bp->b_npages = index; 3174 } 3175 3176 void 3177 vm_hold_free_pages(struct buf * bp, vm_offset_t from, vm_offset_t to) 3178 { 3179 vm_offset_t pg; 3180 vm_page_t p; 3181 int index, newnpages; 3182 3183 from = round_page(from); 3184 to = round_page(to); 3185 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3186 3187 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3188 p = bp->b_pages[index]; 3189 if (p && (index < bp->b_npages)) { 3190 if (p->busy) { 3191 printf("vm_hold_free_pages: blkno: %d, lblkno: %d\n", 3192 bp->b_blkno, bp->b_lblkno); 3193 } 3194 bp->b_pages[index] = NULL; 3195 pmap_kremove(pg); 3196 vm_page_busy(p); 3197 vm_page_unwire(p, 0); 3198 vm_page_free(p); 3199 } 3200 } 3201 bp->b_npages = newnpages; 3202 } 3203 3204 /* 3205 * Map an IO request into kernel virtual address space. 3206 * 3207 * All requests are (re)mapped into kernel VA space. 3208 * Notice that we use b_bufsize for the size of the buffer 3209 * to be mapped. b_bcount might be modified by the driver. 3210 */ 3211 int 3212 vmapbuf(struct buf *bp) 3213 { 3214 caddr_t addr, v, kva; 3215 vm_paddr_t pa; 3216 int pidx; 3217 int i; 3218 struct vm_page *m; 3219 3220 if ((bp->b_flags & B_PHYS) == 0) 3221 panic("vmapbuf"); 3222 if (bp->b_bufsize < 0) 3223 return (-1); 3224 for (v = bp->b_saveaddr, 3225 addr = (caddr_t)trunc_page((vm_offset_t)bp->b_data), 3226 pidx = 0; 3227 addr < bp->b_data + bp->b_bufsize; 3228 addr += PAGE_SIZE, v += PAGE_SIZE, pidx++) { 3229 /* 3230 * Do the vm_fault if needed; do the copy-on-write thing 3231 * when reading stuff off device into memory. 3232 */ 3233 retry: 3234 i = vm_fault_quick((addr >= bp->b_data) ? addr : bp->b_data, 3235 (bp->b_flags&B_READ)?(VM_PROT_READ|VM_PROT_WRITE):VM_PROT_READ); 3236 if (i < 0) { 3237 for (i = 0; i < pidx; ++i) { 3238 vm_page_unhold(bp->b_pages[i]); 3239 bp->b_pages[i] = NULL; 3240 } 3241 return(-1); 3242 } 3243 3244 /* 3245 * WARNING! If sparc support is MFCd in the future this will 3246 * have to be changed from pmap_kextract() to pmap_extract() 3247 * ala -current. 3248 */ 3249 #ifdef __sparc64__ 3250 #error "If MFCing sparc support use pmap_extract" 3251 #endif 3252 pa = pmap_kextract((vm_offset_t)addr); 3253 if (pa == 0) { 3254 printf("vmapbuf: warning, race against user address during I/O"); 3255 goto retry; 3256 } 3257 m = PHYS_TO_VM_PAGE(pa); 3258 vm_page_hold(m); 3259 bp->b_pages[pidx] = m; 3260 } 3261 if (pidx > btoc(MAXPHYS)) 3262 panic("vmapbuf: mapped more than MAXPHYS"); 3263 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx); 3264 3265 kva = bp->b_saveaddr; 3266 bp->b_npages = pidx; 3267 bp->b_saveaddr = bp->b_data; 3268 bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK); 3269 return(0); 3270 } 3271 3272 /* 3273 * Free the io map PTEs associated with this IO operation. 3274 * We also invalidate the TLB entries and restore the original b_addr. 3275 */ 3276 void 3277 vunmapbuf(bp) 3278 struct buf *bp; 3279 { 3280 int pidx; 3281 int npages; 3282 vm_page_t *m; 3283 3284 if ((bp->b_flags & B_PHYS) == 0) 3285 panic("vunmapbuf"); 3286 3287 npages = bp->b_npages; 3288 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), 3289 npages); 3290 m = bp->b_pages; 3291 for (pidx = 0; pidx < npages; pidx++) 3292 vm_page_unhold(*m++); 3293 3294 bp->b_data = bp->b_saveaddr; 3295 } 3296 3297 #include "opt_ddb.h" 3298 #ifdef DDB 3299 #include <ddb/ddb.h> 3300 3301 DB_SHOW_COMMAND(buffer, db_show_buffer) 3302 { 3303 /* get args */ 3304 struct buf *bp = (struct buf *)addr; 3305 3306 if (!have_addr) { 3307 db_printf("usage: show buffer <addr>\n"); 3308 return; 3309 } 3310 3311 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS); 3312 db_printf("b_error = %d, b_bufsize = %ld, b_bcount = %ld, " 3313 "b_resid = %ld\nb_dev = (%d,%d), b_data = %p, " 3314 "b_blkno = %d, b_pblkno = %d\n", 3315 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 3316 major(bp->b_dev), minor(bp->b_dev), 3317 bp->b_data, bp->b_blkno, bp->b_pblkno); 3318 if (bp->b_npages) { 3319 int i; 3320 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 3321 for (i = 0; i < bp->b_npages; i++) { 3322 vm_page_t m; 3323 m = bp->b_pages[i]; 3324 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 3325 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 3326 if ((i + 1) < bp->b_npages) 3327 db_printf(","); 3328 } 3329 db_printf("\n"); 3330 } 3331 } 3332 #endif /* DDB */ 3333