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 * $FreeBSD$ 15 */ 16 17 /* 18 * this file contains a new buffer I/O scheme implementing a coherent 19 * VM object and buffer cache scheme. Pains have been taken to make 20 * sure that the performance degradation associated with schemes such 21 * as this is not realized. 22 * 23 * Author: John S. Dyson 24 * Significant help during the development and debugging phases 25 * had been provided by David Greenman, also of the FreeBSD core team. 26 * 27 * see man buf(9) for more info. 28 */ 29 30 #include <sys/param.h> 31 #include <sys/systm.h> 32 #include <sys/bio.h> 33 #include <sys/buf.h> 34 #include <sys/eventhandler.h> 35 #include <sys/lock.h> 36 #include <sys/malloc.h> 37 #include <sys/mount.h> 38 #include <sys/mutex.h> 39 #include <sys/kernel.h> 40 #include <sys/kthread.h> 41 #include <sys/ktr.h> 42 #include <sys/proc.h> 43 #include <sys/reboot.h> 44 #include <sys/resourcevar.h> 45 #include <sys/sysctl.h> 46 #include <sys/vmmeter.h> 47 #include <sys/vnode.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 57 static MALLOC_DEFINE(M_BIOBUF, "BIO buffer", "BIO buffer"); 58 59 struct bio_ops bioops; /* I/O operation notification */ 60 61 struct buf *buf; /* buffer header pool */ 62 struct swqueue bswlist; 63 struct mtx buftimelock; /* Interlock on setting prio and timo */ 64 65 static void vm_hold_free_pages(struct buf * bp, vm_offset_t from, 66 vm_offset_t to); 67 static void vm_hold_load_pages(struct buf * bp, vm_offset_t from, 68 vm_offset_t to); 69 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, 70 int pageno, vm_page_t m); 71 static void vfs_clean_pages(struct buf * bp); 72 static void vfs_setdirty(struct buf *bp); 73 static void vfs_vmio_release(struct buf *bp); 74 static void vfs_backgroundwritedone(struct buf *bp); 75 static int flushbufqueues(void); 76 77 static int bd_request; 78 79 static void buf_daemon __P((void)); 80 /* 81 * bogus page -- for I/O to/from partially complete buffers 82 * this is a temporary solution to the problem, but it is not 83 * really that bad. it would be better to split the buffer 84 * for input in the case of buffers partially already in memory, 85 * but the code is intricate enough already. 86 */ 87 vm_page_t bogus_page; 88 int vmiodirenable = FALSE; 89 int runningbufspace; 90 static vm_offset_t bogus_offset; 91 92 static int bufspace, maxbufspace, 93 bufmallocspace, maxbufmallocspace, lobufspace, hibufspace; 94 static int bufreusecnt, bufdefragcnt, buffreekvacnt; 95 static int needsbuffer; 96 static int lorunningspace, hirunningspace, runningbufreq; 97 static int numdirtybuffers, lodirtybuffers, hidirtybuffers; 98 static int numfreebuffers, lofreebuffers, hifreebuffers; 99 static int getnewbufcalls; 100 static int getnewbufrestarts; 101 102 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, 103 &numdirtybuffers, 0, ""); 104 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, 105 &lodirtybuffers, 0, ""); 106 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, 107 &hidirtybuffers, 0, ""); 108 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, 109 &numfreebuffers, 0, ""); 110 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, 111 &lofreebuffers, 0, ""); 112 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, 113 &hifreebuffers, 0, ""); 114 SYSCTL_INT(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, 115 &runningbufspace, 0, ""); 116 SYSCTL_INT(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, 117 &lorunningspace, 0, ""); 118 SYSCTL_INT(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, 119 &hirunningspace, 0, ""); 120 SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, 121 &maxbufspace, 0, ""); 122 SYSCTL_INT(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, 123 &hibufspace, 0, ""); 124 SYSCTL_INT(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, 125 &lobufspace, 0, ""); 126 SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, 127 &bufspace, 0, ""); 128 SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, 129 &maxbufmallocspace, 0, ""); 130 SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, 131 &bufmallocspace, 0, ""); 132 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, 133 &getnewbufcalls, 0, ""); 134 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, 135 &getnewbufrestarts, 0, ""); 136 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, 137 &vmiodirenable, 0, ""); 138 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, 139 &bufdefragcnt, 0, ""); 140 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, 141 &buffreekvacnt, 0, ""); 142 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, 143 &bufreusecnt, 0, ""); 144 145 static int bufhashmask; 146 static LIST_HEAD(bufhashhdr, buf) *bufhashtbl, invalhash; 147 struct bqueues bufqueues[BUFFER_QUEUES] = { { 0 } }; 148 char *buf_wmesg = BUF_WMESG; 149 150 extern int vm_swap_size; 151 152 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 153 #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */ 154 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ 155 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 156 157 /* 158 * Buffer hash table code. Note that the logical block scans linearly, which 159 * gives us some L1 cache locality. 160 */ 161 162 static __inline 163 struct bufhashhdr * 164 bufhash(struct vnode *vnp, daddr_t bn) 165 { 166 return(&bufhashtbl[(((uintptr_t)(vnp) >> 7) + (int)bn) & bufhashmask]); 167 } 168 169 /* 170 * numdirtywakeup: 171 * 172 * If someone is blocked due to there being too many dirty buffers, 173 * and numdirtybuffers is now reasonable, wake them up. 174 */ 175 176 static __inline void 177 numdirtywakeup(int level) 178 { 179 if (numdirtybuffers <= level) { 180 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) { 181 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH; 182 wakeup(&needsbuffer); 183 } 184 } 185 } 186 187 /* 188 * bufspacewakeup: 189 * 190 * Called when buffer space is potentially available for recovery. 191 * getnewbuf() will block on this flag when it is unable to free 192 * sufficient buffer space. Buffer space becomes recoverable when 193 * bp's get placed back in the queues. 194 */ 195 196 static __inline void 197 bufspacewakeup(void) 198 { 199 /* 200 * If someone is waiting for BUF space, wake them up. Even 201 * though we haven't freed the kva space yet, the waiting 202 * process will be able to now. 203 */ 204 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) { 205 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE; 206 wakeup(&needsbuffer); 207 } 208 } 209 210 /* 211 * runningbufwakeup() - in-progress I/O accounting. 212 * 213 */ 214 static __inline void 215 runningbufwakeup(struct buf *bp) 216 { 217 if (bp->b_runningbufspace) { 218 runningbufspace -= bp->b_runningbufspace; 219 bp->b_runningbufspace = 0; 220 if (runningbufreq && runningbufspace <= lorunningspace) { 221 runningbufreq = 0; 222 wakeup(&runningbufreq); 223 } 224 } 225 } 226 227 /* 228 * bufcountwakeup: 229 * 230 * Called when a buffer has been added to one of the free queues to 231 * account for the buffer and to wakeup anyone waiting for free buffers. 232 * This typically occurs when large amounts of metadata are being handled 233 * by the buffer cache ( else buffer space runs out first, usually ). 234 */ 235 236 static __inline void 237 bufcountwakeup(void) 238 { 239 ++numfreebuffers; 240 if (needsbuffer) { 241 needsbuffer &= ~VFS_BIO_NEED_ANY; 242 if (numfreebuffers >= hifreebuffers) 243 needsbuffer &= ~VFS_BIO_NEED_FREE; 244 wakeup(&needsbuffer); 245 } 246 } 247 248 /* 249 * waitrunningbufspace() 250 * 251 * runningbufspace is a measure of the amount of I/O currently 252 * running. This routine is used in async-write situations to 253 * prevent creating huge backups of pending writes to a device. 254 * Only asynchronous writes are governed by this function. 255 * 256 * Reads will adjust runningbufspace, but will not block based on it. 257 * The read load has a side effect of reducing the allowed write load. 258 * 259 * This does NOT turn an async write into a sync write. It waits 260 * for earlier writes to complete and generally returns before the 261 * caller's write has reached the device. 262 */ 263 static __inline void 264 waitrunningbufspace(void) 265 { 266 while (runningbufspace > hirunningspace) { 267 ++runningbufreq; 268 tsleep(&runningbufreq, PVM, "wdrain", 0); 269 } 270 } 271 272 273 /* 274 * vfs_buf_test_cache: 275 * 276 * Called when a buffer is extended. This function clears the B_CACHE 277 * bit if the newly extended portion of the buffer does not contain 278 * valid data. 279 */ 280 static __inline__ 281 void 282 vfs_buf_test_cache(struct buf *bp, 283 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 284 vm_page_t m) 285 { 286 if (bp->b_flags & B_CACHE) { 287 int base = (foff + off) & PAGE_MASK; 288 if (vm_page_is_valid(m, base, size) == 0) 289 bp->b_flags &= ~B_CACHE; 290 } 291 } 292 293 static __inline__ 294 void 295 bd_wakeup(int dirtybuflevel) 296 { 297 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) { 298 bd_request = 1; 299 wakeup(&bd_request); 300 } 301 } 302 303 /* 304 * bd_speedup - speedup the buffer cache flushing code 305 */ 306 307 static __inline__ 308 void 309 bd_speedup(void) 310 { 311 bd_wakeup(1); 312 } 313 314 /* 315 * Initialize buffer headers and related structures. 316 */ 317 318 caddr_t 319 bufhashinit(caddr_t vaddr) 320 { 321 /* first, make a null hash table */ 322 for (bufhashmask = 8; bufhashmask < nbuf / 4; bufhashmask <<= 1) 323 ; 324 bufhashtbl = (void *)vaddr; 325 vaddr = vaddr + sizeof(*bufhashtbl) * bufhashmask; 326 --bufhashmask; 327 return(vaddr); 328 } 329 330 void 331 bufinit(void) 332 { 333 struct buf *bp; 334 int i; 335 336 TAILQ_INIT(&bswlist); 337 LIST_INIT(&invalhash); 338 mtx_init(&buftimelock, "buftime lock", MTX_DEF); 339 340 for (i = 0; i <= bufhashmask; i++) 341 LIST_INIT(&bufhashtbl[i]); 342 343 /* next, make a null set of free lists */ 344 for (i = 0; i < BUFFER_QUEUES; i++) 345 TAILQ_INIT(&bufqueues[i]); 346 347 /* finally, initialize each buffer header and stick on empty q */ 348 for (i = 0; i < nbuf; i++) { 349 bp = &buf[i]; 350 bzero(bp, sizeof *bp); 351 bp->b_flags = B_INVAL; /* we're just an empty header */ 352 bp->b_dev = NODEV; 353 bp->b_rcred = NOCRED; 354 bp->b_wcred = NOCRED; 355 bp->b_qindex = QUEUE_EMPTY; 356 bp->b_xflags = 0; 357 LIST_INIT(&bp->b_dep); 358 BUF_LOCKINIT(bp); 359 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 360 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 361 } 362 363 /* 364 * maxbufspace is the absolute maximum amount of buffer space we are 365 * allowed to reserve in KVM and in real terms. The absolute maximum 366 * is nominally used by buf_daemon. hibufspace is the nominal maximum 367 * used by most other processes. The differential is required to 368 * ensure that buf_daemon is able to run when other processes might 369 * be blocked waiting for buffer space. 370 * 371 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 372 * this may result in KVM fragmentation which is not handled optimally 373 * by the system. 374 */ 375 maxbufspace = nbuf * BKVASIZE; 376 hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 377 lobufspace = hibufspace - MAXBSIZE; 378 379 lorunningspace = 512 * 1024; 380 hirunningspace = 1024 * 1024; 381 382 /* 383 * Limit the amount of malloc memory since it is wired permanently into 384 * the kernel space. Even though this is accounted for in the buffer 385 * allocation, we don't want the malloced region to grow uncontrolled. 386 * The malloc scheme improves memory utilization significantly on average 387 * (small) directories. 388 */ 389 maxbufmallocspace = hibufspace / 20; 390 391 /* 392 * Reduce the chance of a deadlock occuring by limiting the number 393 * of delayed-write dirty buffers we allow to stack up. 394 */ 395 hidirtybuffers = nbuf / 4 + 20; 396 numdirtybuffers = 0; 397 /* 398 * To support extreme low-memory systems, make sure hidirtybuffers cannot 399 * eat up all available buffer space. This occurs when our minimum cannot 400 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 401 * BKVASIZE'd (8K) buffers. 402 */ 403 while (hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 404 hidirtybuffers >>= 1; 405 } 406 lodirtybuffers = hidirtybuffers / 2; 407 408 /* 409 * Try to keep the number of free buffers in the specified range, 410 * and give special processes (e.g. like buf_daemon) access to an 411 * emergency reserve. 412 */ 413 lofreebuffers = nbuf / 18 + 5; 414 hifreebuffers = 2 * lofreebuffers; 415 numfreebuffers = nbuf; 416 417 /* 418 * Maximum number of async ops initiated per buf_daemon loop. This is 419 * somewhat of a hack at the moment, we really need to limit ourselves 420 * based on the number of bytes of I/O in-transit that were initiated 421 * from buf_daemon. 422 */ 423 424 bogus_offset = kmem_alloc_pageable(kernel_map, PAGE_SIZE); 425 bogus_page = vm_page_alloc(kernel_object, 426 ((bogus_offset - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 427 VM_ALLOC_NORMAL); 428 cnt.v_wire_count++; 429 430 } 431 432 /* 433 * bfreekva() - free the kva allocation for a buffer. 434 * 435 * Must be called at splbio() or higher as this is the only locking for 436 * buffer_map. 437 * 438 * Since this call frees up buffer space, we call bufspacewakeup(). 439 */ 440 static void 441 bfreekva(struct buf * bp) 442 { 443 if (bp->b_kvasize) { 444 ++buffreekvacnt; 445 bufspace -= bp->b_kvasize; 446 vm_map_delete(buffer_map, 447 (vm_offset_t) bp->b_kvabase, 448 (vm_offset_t) bp->b_kvabase + bp->b_kvasize 449 ); 450 bp->b_kvasize = 0; 451 bufspacewakeup(); 452 } 453 } 454 455 /* 456 * bremfree: 457 * 458 * Remove the buffer from the appropriate free list. 459 */ 460 void 461 bremfree(struct buf * bp) 462 { 463 int s = splbio(); 464 int old_qindex = bp->b_qindex; 465 466 if (bp->b_qindex != QUEUE_NONE) { 467 KASSERT(BUF_REFCNT(bp) == 1, ("bremfree: bp %p not locked",bp)); 468 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 469 bp->b_qindex = QUEUE_NONE; 470 } else { 471 if (BUF_REFCNT(bp) <= 1) 472 panic("bremfree: removing a buffer not on a queue"); 473 } 474 475 /* 476 * Fixup numfreebuffers count. If the buffer is invalid or not 477 * delayed-write, and it was on the EMPTY, LRU, or AGE queues, 478 * the buffer was free and we must decrement numfreebuffers. 479 */ 480 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { 481 switch(old_qindex) { 482 case QUEUE_DIRTY: 483 case QUEUE_CLEAN: 484 case QUEUE_EMPTY: 485 case QUEUE_EMPTYKVA: 486 --numfreebuffers; 487 break; 488 default: 489 break; 490 } 491 } 492 splx(s); 493 } 494 495 496 /* 497 * Get a buffer with the specified data. Look in the cache first. We 498 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 499 * is set, the buffer is valid and we do not have to do anything ( see 500 * getblk() ). 501 */ 502 int 503 bread(struct vnode * vp, daddr_t blkno, int size, struct ucred * cred, 504 struct buf ** bpp) 505 { 506 struct buf *bp; 507 508 bp = getblk(vp, blkno, size, 0, 0); 509 *bpp = bp; 510 511 /* if not found in cache, do some I/O */ 512 if ((bp->b_flags & B_CACHE) == 0) { 513 if (curproc != idleproc) 514 curproc->p_stats->p_ru.ru_inblock++; 515 KASSERT(!(bp->b_flags & B_ASYNC), ("bread: illegal async bp %p", bp)); 516 bp->b_iocmd = BIO_READ; 517 bp->b_flags &= ~B_INVAL; 518 bp->b_ioflags &= ~BIO_ERROR; 519 if (bp->b_rcred == NOCRED) { 520 if (cred != NOCRED) 521 crhold(cred); 522 bp->b_rcred = cred; 523 } 524 vfs_busy_pages(bp, 0); 525 VOP_STRATEGY(vp, bp); 526 return (bufwait(bp)); 527 } 528 return (0); 529 } 530 531 /* 532 * Operates like bread, but also starts asynchronous I/O on 533 * read-ahead blocks. We must clear BIO_ERROR and B_INVAL prior 534 * to initiating I/O . If B_CACHE is set, the buffer is valid 535 * and we do not have to do anything. 536 */ 537 int 538 breadn(struct vnode * vp, daddr_t blkno, int size, 539 daddr_t * rablkno, int *rabsize, 540 int cnt, struct ucred * cred, struct buf ** bpp) 541 { 542 struct buf *bp, *rabp; 543 int i; 544 int rv = 0, readwait = 0; 545 546 *bpp = bp = getblk(vp, blkno, size, 0, 0); 547 548 /* if not found in cache, do some I/O */ 549 if ((bp->b_flags & B_CACHE) == 0) { 550 if (curproc != idleproc) 551 curproc->p_stats->p_ru.ru_inblock++; 552 bp->b_iocmd = BIO_READ; 553 bp->b_flags &= ~B_INVAL; 554 bp->b_ioflags &= ~BIO_ERROR; 555 if (bp->b_rcred == NOCRED) { 556 if (cred != NOCRED) 557 crhold(cred); 558 bp->b_rcred = cred; 559 } 560 vfs_busy_pages(bp, 0); 561 VOP_STRATEGY(vp, bp); 562 ++readwait; 563 } 564 565 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 566 if (inmem(vp, *rablkno)) 567 continue; 568 rabp = getblk(vp, *rablkno, *rabsize, 0, 0); 569 570 if ((rabp->b_flags & B_CACHE) == 0) { 571 if (curproc != idleproc) 572 curproc->p_stats->p_ru.ru_inblock++; 573 rabp->b_flags |= B_ASYNC; 574 rabp->b_flags &= ~B_INVAL; 575 rabp->b_ioflags &= ~BIO_ERROR; 576 rabp->b_iocmd = BIO_READ; 577 if (rabp->b_rcred == NOCRED) { 578 if (cred != NOCRED) 579 crhold(cred); 580 rabp->b_rcred = cred; 581 } 582 vfs_busy_pages(rabp, 0); 583 BUF_KERNPROC(rabp); 584 VOP_STRATEGY(vp, rabp); 585 } else { 586 brelse(rabp); 587 } 588 } 589 590 if (readwait) { 591 rv = bufwait(bp); 592 } 593 return (rv); 594 } 595 596 /* 597 * Write, release buffer on completion. (Done by iodone 598 * if async). Do not bother writing anything if the buffer 599 * is invalid. 600 * 601 * Note that we set B_CACHE here, indicating that buffer is 602 * fully valid and thus cacheable. This is true even of NFS 603 * now so we set it generally. This could be set either here 604 * or in biodone() since the I/O is synchronous. We put it 605 * here. 606 */ 607 int 608 bwrite(struct buf * bp) 609 { 610 int oldflags, s; 611 struct buf *newbp; 612 613 if (bp->b_flags & B_INVAL) { 614 brelse(bp); 615 return (0); 616 } 617 618 oldflags = bp->b_flags; 619 620 if (BUF_REFCNT(bp) == 0) 621 panic("bwrite: buffer is not busy???"); 622 s = splbio(); 623 /* 624 * If a background write is already in progress, delay 625 * writing this block if it is asynchronous. Otherwise 626 * wait for the background write to complete. 627 */ 628 if (bp->b_xflags & BX_BKGRDINPROG) { 629 if (bp->b_flags & B_ASYNC) { 630 splx(s); 631 bdwrite(bp); 632 return (0); 633 } 634 bp->b_xflags |= BX_BKGRDWAIT; 635 tsleep(&bp->b_xflags, PRIBIO, "biord", 0); 636 if (bp->b_xflags & BX_BKGRDINPROG) 637 panic("bwrite: still writing"); 638 } 639 640 /* Mark the buffer clean */ 641 bundirty(bp); 642 643 /* 644 * If this buffer is marked for background writing and we 645 * do not have to wait for it, make a copy and write the 646 * copy so as to leave this buffer ready for further use. 647 * 648 * This optimization eats a lot of memory. If we have a page 649 * or buffer shortfall we can't do it. 650 */ 651 if ((bp->b_xflags & BX_BKGRDWRITE) && 652 (bp->b_flags & B_ASYNC) && 653 !vm_page_count_severe() && 654 !buf_dirty_count_severe()) { 655 if (bp->b_iodone != NULL) { 656 printf("bp->b_iodone = %p\n", bp->b_iodone); 657 panic("bwrite: need chained iodone"); 658 } 659 660 /* get a new block */ 661 newbp = geteblk(bp->b_bufsize); 662 663 /* set it to be identical to the old block */ 664 memcpy(newbp->b_data, bp->b_data, bp->b_bufsize); 665 bgetvp(bp->b_vp, newbp); 666 newbp->b_lblkno = bp->b_lblkno; 667 newbp->b_blkno = bp->b_blkno; 668 newbp->b_offset = bp->b_offset; 669 newbp->b_iodone = vfs_backgroundwritedone; 670 newbp->b_flags |= B_ASYNC; 671 newbp->b_flags &= ~B_INVAL; 672 673 /* move over the dependencies */ 674 if (LIST_FIRST(&bp->b_dep) != NULL) 675 buf_movedeps(bp, newbp); 676 677 /* 678 * Initiate write on the copy, release the original to 679 * the B_LOCKED queue so that it cannot go away until 680 * the background write completes. If not locked it could go 681 * away and then be reconstituted while it was being written. 682 * If the reconstituted buffer were written, we could end up 683 * with two background copies being written at the same time. 684 */ 685 bp->b_xflags |= BX_BKGRDINPROG; 686 bp->b_flags |= B_LOCKED; 687 bqrelse(bp); 688 bp = newbp; 689 } 690 691 bp->b_flags &= ~B_DONE; 692 bp->b_ioflags &= ~BIO_ERROR; 693 bp->b_flags |= B_WRITEINPROG | B_CACHE; 694 bp->b_iocmd = BIO_WRITE; 695 696 bp->b_vp->v_numoutput++; 697 vfs_busy_pages(bp, 1); 698 if (curproc != idleproc) 699 curproc->p_stats->p_ru.ru_oublock++; 700 splx(s); 701 if (oldflags & B_ASYNC) 702 BUF_KERNPROC(bp); 703 BUF_STRATEGY(bp); 704 705 if ((oldflags & B_ASYNC) == 0) { 706 int rtval = bufwait(bp); 707 brelse(bp); 708 return (rtval); 709 } else { 710 /* 711 * don't allow the async write to saturate the I/O 712 * system. There is no chance of deadlock here because 713 * we are blocking on I/O that is already in-progress. 714 */ 715 waitrunningbufspace(); 716 } 717 718 return (0); 719 } 720 721 /* 722 * Complete a background write started from bwrite. 723 */ 724 static void 725 vfs_backgroundwritedone(bp) 726 struct buf *bp; 727 { 728 struct buf *origbp; 729 730 /* 731 * Find the original buffer that we are writing. 732 */ 733 if ((origbp = gbincore(bp->b_vp, bp->b_lblkno)) == NULL) 734 panic("backgroundwritedone: lost buffer"); 735 /* 736 * Process dependencies then return any unfinished ones. 737 */ 738 if (LIST_FIRST(&bp->b_dep) != NULL) 739 buf_complete(bp); 740 if (LIST_FIRST(&bp->b_dep) != NULL) 741 buf_movedeps(bp, origbp); 742 /* 743 * Clear the BX_BKGRDINPROG flag in the original buffer 744 * and awaken it if it is waiting for the write to complete. 745 * If BX_BKGRDINPROG is not set in the original buffer it must 746 * have been released and re-instantiated - which is not legal. 747 */ 748 KASSERT((origbp->b_xflags & BX_BKGRDINPROG), ("backgroundwritedone: lost buffer2")); 749 origbp->b_xflags &= ~BX_BKGRDINPROG; 750 if (origbp->b_xflags & BX_BKGRDWAIT) { 751 origbp->b_xflags &= ~BX_BKGRDWAIT; 752 wakeup(&origbp->b_xflags); 753 } 754 /* 755 * Clear the B_LOCKED flag and remove it from the locked 756 * queue if it currently resides there. 757 */ 758 origbp->b_flags &= ~B_LOCKED; 759 if (BUF_LOCK(origbp, LK_EXCLUSIVE | LK_NOWAIT) == 0) { 760 bremfree(origbp); 761 bqrelse(origbp); 762 } 763 /* 764 * This buffer is marked B_NOCACHE, so when it is released 765 * by biodone, it will be tossed. We mark it with BIO_READ 766 * to avoid biodone doing a second vwakeup. 767 */ 768 bp->b_flags |= B_NOCACHE; 769 bp->b_iocmd = BIO_READ; 770 bp->b_flags &= ~(B_CACHE | B_DONE); 771 bp->b_iodone = 0; 772 bufdone(bp); 773 } 774 775 /* 776 * Delayed write. (Buffer is marked dirty). Do not bother writing 777 * anything if the buffer is marked invalid. 778 * 779 * Note that since the buffer must be completely valid, we can safely 780 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 781 * biodone() in order to prevent getblk from writing the buffer 782 * out synchronously. 783 */ 784 void 785 bdwrite(struct buf * bp) 786 { 787 if (BUF_REFCNT(bp) == 0) 788 panic("bdwrite: buffer is not busy"); 789 790 if (bp->b_flags & B_INVAL) { 791 brelse(bp); 792 return; 793 } 794 bdirty(bp); 795 796 /* 797 * Set B_CACHE, indicating that the buffer is fully valid. This is 798 * true even of NFS now. 799 */ 800 bp->b_flags |= B_CACHE; 801 802 /* 803 * This bmap keeps the system from needing to do the bmap later, 804 * perhaps when the system is attempting to do a sync. Since it 805 * is likely that the indirect block -- or whatever other datastructure 806 * that the filesystem needs is still in memory now, it is a good 807 * thing to do this. Note also, that if the pageout daemon is 808 * requesting a sync -- there might not be enough memory to do 809 * the bmap then... So, this is important to do. 810 */ 811 if (bp->b_lblkno == bp->b_blkno) { 812 VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 813 } 814 815 /* 816 * Set the *dirty* buffer range based upon the VM system dirty pages. 817 */ 818 vfs_setdirty(bp); 819 820 /* 821 * We need to do this here to satisfy the vnode_pager and the 822 * pageout daemon, so that it thinks that the pages have been 823 * "cleaned". Note that since the pages are in a delayed write 824 * buffer -- the VFS layer "will" see that the pages get written 825 * out on the next sync, or perhaps the cluster will be completed. 826 */ 827 vfs_clean_pages(bp); 828 bqrelse(bp); 829 830 /* 831 * Wakeup the buffer flushing daemon if we have a lot of dirty 832 * buffers (midpoint between our recovery point and our stall 833 * point). 834 */ 835 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 836 837 /* 838 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 839 * due to the softdep code. 840 */ 841 } 842 843 /* 844 * bdirty: 845 * 846 * Turn buffer into delayed write request. We must clear BIO_READ and 847 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 848 * itself to properly update it in the dirty/clean lists. We mark it 849 * B_DONE to ensure that any asynchronization of the buffer properly 850 * clears B_DONE ( else a panic will occur later ). 851 * 852 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 853 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 854 * should only be called if the buffer is known-good. 855 * 856 * Since the buffer is not on a queue, we do not update the numfreebuffers 857 * count. 858 * 859 * Must be called at splbio(). 860 * The buffer must be on QUEUE_NONE. 861 */ 862 void 863 bdirty(bp) 864 struct buf *bp; 865 { 866 KASSERT(bp->b_qindex == QUEUE_NONE, ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 867 bp->b_flags &= ~(B_RELBUF); 868 bp->b_iocmd = BIO_WRITE; 869 870 if ((bp->b_flags & B_DELWRI) == 0) { 871 bp->b_flags |= B_DONE | B_DELWRI; 872 reassignbuf(bp, bp->b_vp); 873 ++numdirtybuffers; 874 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 875 } 876 } 877 878 /* 879 * bundirty: 880 * 881 * Clear B_DELWRI for buffer. 882 * 883 * Since the buffer is not on a queue, we do not update the numfreebuffers 884 * count. 885 * 886 * Must be called at splbio(). 887 * The buffer must be on QUEUE_NONE. 888 */ 889 890 void 891 bundirty(bp) 892 struct buf *bp; 893 { 894 KASSERT(bp->b_qindex == QUEUE_NONE, ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 895 896 if (bp->b_flags & B_DELWRI) { 897 bp->b_flags &= ~B_DELWRI; 898 reassignbuf(bp, bp->b_vp); 899 --numdirtybuffers; 900 numdirtywakeup(lodirtybuffers); 901 } 902 /* 903 * Since it is now being written, we can clear its deferred write flag. 904 */ 905 bp->b_flags &= ~B_DEFERRED; 906 } 907 908 /* 909 * bawrite: 910 * 911 * Asynchronous write. Start output on a buffer, but do not wait for 912 * it to complete. The buffer is released when the output completes. 913 * 914 * bwrite() ( or the VOP routine anyway ) is responsible for handling 915 * B_INVAL buffers. Not us. 916 */ 917 void 918 bawrite(struct buf * bp) 919 { 920 bp->b_flags |= B_ASYNC; 921 (void) BUF_WRITE(bp); 922 } 923 924 /* 925 * bowrite: 926 * 927 * Ordered write. Start output on a buffer, and flag it so that the 928 * device will write it in the order it was queued. The buffer is 929 * released when the output completes. bwrite() ( or the VOP routine 930 * anyway ) is responsible for handling B_INVAL buffers. 931 */ 932 int 933 bowrite(struct buf * bp) 934 { 935 bp->b_ioflags |= BIO_ORDERED; 936 bp->b_flags |= B_ASYNC; 937 return (BUF_WRITE(bp)); 938 } 939 940 /* 941 * bwillwrite: 942 * 943 * Called prior to the locking of any vnodes when we are expecting to 944 * write. We do not want to starve the buffer cache with too many 945 * dirty buffers so we block here. By blocking prior to the locking 946 * of any vnodes we attempt to avoid the situation where a locked vnode 947 * prevents the various system daemons from flushing related buffers. 948 */ 949 950 void 951 bwillwrite(void) 952 { 953 if (numdirtybuffers >= hidirtybuffers) { 954 int s; 955 956 s = splbio(); 957 while (numdirtybuffers >= hidirtybuffers) { 958 bd_wakeup(1); 959 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH; 960 tsleep(&needsbuffer, (PRIBIO + 4), "flswai", 0); 961 } 962 splx(s); 963 } 964 } 965 966 /* 967 * Return true if we have too many dirty buffers. 968 */ 969 int 970 buf_dirty_count_severe(void) 971 { 972 return(numdirtybuffers >= hidirtybuffers); 973 } 974 975 /* 976 * brelse: 977 * 978 * Release a busy buffer and, if requested, free its resources. The 979 * buffer will be stashed in the appropriate bufqueue[] allowing it 980 * to be accessed later as a cache entity or reused for other purposes. 981 */ 982 void 983 brelse(struct buf * bp) 984 { 985 int s; 986 987 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 988 989 s = splbio(); 990 991 if (bp->b_flags & B_LOCKED) 992 bp->b_ioflags &= ~BIO_ERROR; 993 994 if (bp->b_iocmd == BIO_WRITE && 995 (bp->b_ioflags & BIO_ERROR) && 996 !(bp->b_flags & B_INVAL)) { 997 /* 998 * Failed write, redirty. Must clear BIO_ERROR to prevent 999 * pages from being scrapped. If B_INVAL is set then 1000 * this case is not run and the next case is run to 1001 * destroy the buffer. B_INVAL can occur if the buffer 1002 * is outside the range supported by the underlying device. 1003 */ 1004 bp->b_ioflags &= ~BIO_ERROR; 1005 bdirty(bp); 1006 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 1007 (bp->b_ioflags & BIO_ERROR) || 1008 bp->b_iocmd == BIO_DELETE || (bp->b_bufsize <= 0)) { 1009 /* 1010 * Either a failed I/O or we were asked to free or not 1011 * cache the buffer. 1012 */ 1013 bp->b_flags |= B_INVAL; 1014 if (LIST_FIRST(&bp->b_dep) != NULL) 1015 buf_deallocate(bp); 1016 if (bp->b_flags & B_DELWRI) { 1017 --numdirtybuffers; 1018 numdirtywakeup(lodirtybuffers); 1019 } 1020 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1021 if ((bp->b_flags & B_VMIO) == 0) { 1022 if (bp->b_bufsize) 1023 allocbuf(bp, 0); 1024 if (bp->b_vp) 1025 brelvp(bp); 1026 } 1027 } 1028 1029 /* 1030 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1031 * is called with B_DELWRI set, the underlying pages may wind up 1032 * getting freed causing a previous write (bdwrite()) to get 'lost' 1033 * because pages associated with a B_DELWRI bp are marked clean. 1034 * 1035 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1036 * if B_DELWRI is set. 1037 * 1038 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1039 * on pages to return pages to the VM page queues. 1040 */ 1041 if (bp->b_flags & B_DELWRI) 1042 bp->b_flags &= ~B_RELBUF; 1043 else if (vm_page_count_severe() && !(bp->b_xflags & BX_BKGRDINPROG)) 1044 bp->b_flags |= B_RELBUF; 1045 1046 /* 1047 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1048 * constituted, not even NFS buffers now. Two flags effect this. If 1049 * B_INVAL, the struct buf is invalidated but the VM object is kept 1050 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1051 * 1052 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 1053 * invalidated. BIO_ERROR cannot be set for a failed write unless the 1054 * buffer is also B_INVAL because it hits the re-dirtying code above. 1055 * 1056 * Normally we can do this whether a buffer is B_DELWRI or not. If 1057 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1058 * the commit state and we cannot afford to lose the buffer. If the 1059 * buffer has a background write in progress, we need to keep it 1060 * around to prevent it from being reconstituted and starting a second 1061 * background write. 1062 */ 1063 if ((bp->b_flags & B_VMIO) 1064 && !(bp->b_vp->v_tag == VT_NFS && 1065 !vn_isdisk(bp->b_vp, NULL) && 1066 (bp->b_flags & B_DELWRI)) 1067 ) { 1068 1069 int i, j, resid; 1070 vm_page_t m; 1071 off_t foff; 1072 vm_pindex_t poff; 1073 vm_object_t obj; 1074 struct vnode *vp; 1075 1076 vp = bp->b_vp; 1077 1078 /* 1079 * Get the base offset and length of the buffer. Note that 1080 * for block sizes that are less then PAGE_SIZE, the b_data 1081 * base of the buffer does not represent exactly b_offset and 1082 * neither b_offset nor b_size are necessarily page aligned. 1083 * Instead, the starting position of b_offset is: 1084 * 1085 * b_data + (b_offset & PAGE_MASK) 1086 * 1087 * block sizes less then DEV_BSIZE (usually 512) are not 1088 * supported due to the page granularity bits (m->valid, 1089 * m->dirty, etc...). 1090 * 1091 * See man buf(9) for more information 1092 */ 1093 resid = bp->b_bufsize; 1094 foff = bp->b_offset; 1095 1096 for (i = 0; i < bp->b_npages; i++) { 1097 int had_bogus = 0; 1098 1099 m = bp->b_pages[i]; 1100 vm_page_flag_clear(m, PG_ZERO); 1101 1102 /* 1103 * If we hit a bogus page, fixup *all* the bogus pages 1104 * now. 1105 */ 1106 if (m == bogus_page) { 1107 VOP_GETVOBJECT(vp, &obj); 1108 poff = OFF_TO_IDX(bp->b_offset); 1109 had_bogus = 1; 1110 1111 for (j = i; j < bp->b_npages; j++) { 1112 vm_page_t mtmp; 1113 mtmp = bp->b_pages[j]; 1114 if (mtmp == bogus_page) { 1115 mtmp = vm_page_lookup(obj, poff + j); 1116 if (!mtmp) { 1117 panic("brelse: page missing\n"); 1118 } 1119 bp->b_pages[j] = mtmp; 1120 } 1121 } 1122 1123 if ((bp->b_flags & B_INVAL) == 0) { 1124 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 1125 } 1126 m = bp->b_pages[i]; 1127 } 1128 if ((bp->b_flags & B_NOCACHE) || (bp->b_ioflags & BIO_ERROR)) { 1129 int poffset = foff & PAGE_MASK; 1130 int presid = resid > (PAGE_SIZE - poffset) ? 1131 (PAGE_SIZE - poffset) : resid; 1132 1133 KASSERT(presid >= 0, ("brelse: extra page")); 1134 vm_page_set_invalid(m, poffset, presid); 1135 if (had_bogus) 1136 printf("avoided corruption bug in bogus_page/brelse code\n"); 1137 } 1138 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1139 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1140 } 1141 1142 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1143 vfs_vmio_release(bp); 1144 1145 } else if (bp->b_flags & B_VMIO) { 1146 1147 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1148 vfs_vmio_release(bp); 1149 1150 } 1151 1152 if (bp->b_qindex != QUEUE_NONE) 1153 panic("brelse: free buffer onto another queue???"); 1154 if (BUF_REFCNT(bp) > 1) { 1155 /* do not release to free list */ 1156 BUF_UNLOCK(bp); 1157 splx(s); 1158 return; 1159 } 1160 1161 /* enqueue */ 1162 1163 /* buffers with no memory */ 1164 if (bp->b_bufsize == 0) { 1165 bp->b_flags |= B_INVAL; 1166 bp->b_xflags &= ~BX_BKGRDWRITE; 1167 if (bp->b_xflags & BX_BKGRDINPROG) 1168 panic("losing buffer 1"); 1169 if (bp->b_kvasize) { 1170 bp->b_qindex = QUEUE_EMPTYKVA; 1171 } else { 1172 bp->b_qindex = QUEUE_EMPTY; 1173 } 1174 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1175 LIST_REMOVE(bp, b_hash); 1176 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1177 bp->b_dev = NODEV; 1178 /* buffers with junk contents */ 1179 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || (bp->b_ioflags & BIO_ERROR)) { 1180 bp->b_flags |= B_INVAL; 1181 bp->b_xflags &= ~BX_BKGRDWRITE; 1182 if (bp->b_xflags & BX_BKGRDINPROG) 1183 panic("losing buffer 2"); 1184 bp->b_qindex = QUEUE_CLEAN; 1185 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1186 LIST_REMOVE(bp, b_hash); 1187 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1188 bp->b_dev = NODEV; 1189 1190 /* buffers that are locked */ 1191 } else if (bp->b_flags & B_LOCKED) { 1192 bp->b_qindex = QUEUE_LOCKED; 1193 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LOCKED], bp, b_freelist); 1194 1195 /* remaining buffers */ 1196 } else { 1197 switch(bp->b_flags & (B_DELWRI|B_AGE)) { 1198 case B_DELWRI | B_AGE: 1199 bp->b_qindex = QUEUE_DIRTY; 1200 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_DIRTY], bp, b_freelist); 1201 break; 1202 case B_DELWRI: 1203 bp->b_qindex = QUEUE_DIRTY; 1204 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist); 1205 break; 1206 case B_AGE: 1207 bp->b_qindex = QUEUE_CLEAN; 1208 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1209 break; 1210 default: 1211 bp->b_qindex = QUEUE_CLEAN; 1212 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1213 break; 1214 } 1215 } 1216 1217 /* 1218 * If B_INVAL, clear B_DELWRI. We've already placed the buffer 1219 * on the correct queue. 1220 */ 1221 if ((bp->b_flags & (B_INVAL|B_DELWRI)) == (B_INVAL|B_DELWRI)) { 1222 bp->b_flags &= ~B_DELWRI; 1223 --numdirtybuffers; 1224 numdirtywakeup(lodirtybuffers); 1225 } 1226 1227 /* 1228 * Fixup numfreebuffers count. The bp is on an appropriate queue 1229 * unless locked. We then bump numfreebuffers if it is not B_DELWRI. 1230 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1231 * if B_INVAL is set ). 1232 */ 1233 1234 if ((bp->b_flags & B_LOCKED) == 0 && !(bp->b_flags & B_DELWRI)) 1235 bufcountwakeup(); 1236 1237 /* 1238 * Something we can maybe free. 1239 */ 1240 1241 if (bp->b_bufsize || bp->b_kvasize) 1242 bufspacewakeup(); 1243 1244 /* unlock */ 1245 BUF_UNLOCK(bp); 1246 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1247 bp->b_ioflags &= ~BIO_ORDERED; 1248 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1249 panic("brelse: not dirty"); 1250 splx(s); 1251 } 1252 1253 /* 1254 * Release a buffer back to the appropriate queue but do not try to free 1255 * it. The buffer is expected to be used again soon. 1256 * 1257 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1258 * biodone() to requeue an async I/O on completion. It is also used when 1259 * known good buffers need to be requeued but we think we may need the data 1260 * again soon. 1261 */ 1262 void 1263 bqrelse(struct buf * bp) 1264 { 1265 int s; 1266 1267 s = splbio(); 1268 1269 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1270 1271 if (bp->b_qindex != QUEUE_NONE) 1272 panic("bqrelse: free buffer onto another queue???"); 1273 if (BUF_REFCNT(bp) > 1) { 1274 /* do not release to free list */ 1275 BUF_UNLOCK(bp); 1276 splx(s); 1277 return; 1278 } 1279 if (bp->b_flags & B_LOCKED) { 1280 bp->b_ioflags &= ~BIO_ERROR; 1281 bp->b_qindex = QUEUE_LOCKED; 1282 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LOCKED], bp, b_freelist); 1283 /* buffers with stale but valid contents */ 1284 } else if (bp->b_flags & B_DELWRI) { 1285 bp->b_qindex = QUEUE_DIRTY; 1286 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist); 1287 } else if (vm_page_count_severe()) { 1288 /* 1289 * We are too low on memory, we have to try to free the 1290 * buffer (most importantly: the wired pages making up its 1291 * backing store) *now*. 1292 */ 1293 splx(s); 1294 brelse(bp); 1295 return; 1296 } else { 1297 bp->b_qindex = QUEUE_CLEAN; 1298 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1299 } 1300 1301 if ((bp->b_flags & B_LOCKED) == 0 && 1302 ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI))) { 1303 bufcountwakeup(); 1304 } 1305 1306 /* 1307 * Something we can maybe wakeup 1308 */ 1309 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1310 bufspacewakeup(); 1311 1312 /* unlock */ 1313 BUF_UNLOCK(bp); 1314 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1315 bp->b_ioflags &= ~BIO_ORDERED; 1316 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1317 panic("bqrelse: not dirty"); 1318 splx(s); 1319 } 1320 1321 static void 1322 vfs_vmio_release(bp) 1323 struct buf *bp; 1324 { 1325 int i, s; 1326 vm_page_t m; 1327 1328 s = splvm(); 1329 for (i = 0; i < bp->b_npages; i++) { 1330 m = bp->b_pages[i]; 1331 bp->b_pages[i] = NULL; 1332 /* 1333 * In order to keep page LRU ordering consistent, put 1334 * everything on the inactive queue. 1335 */ 1336 vm_page_unwire(m, 0); 1337 /* 1338 * We don't mess with busy pages, it is 1339 * the responsibility of the process that 1340 * busied the pages to deal with them. 1341 */ 1342 if ((m->flags & PG_BUSY) || (m->busy != 0)) 1343 continue; 1344 1345 if (m->wire_count == 0) { 1346 vm_page_flag_clear(m, PG_ZERO); 1347 /* 1348 * Might as well free the page if we can and it has 1349 * no valid data. 1350 */ 1351 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && m->hold_count == 0) { 1352 vm_page_busy(m); 1353 vm_page_protect(m, VM_PROT_NONE); 1354 vm_page_free(m); 1355 } else if (vm_page_count_severe()) { 1356 vm_page_try_to_cache(m); 1357 } 1358 } 1359 } 1360 splx(s); 1361 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages); 1362 if (bp->b_bufsize) { 1363 bufspacewakeup(); 1364 bp->b_bufsize = 0; 1365 } 1366 bp->b_npages = 0; 1367 bp->b_flags &= ~B_VMIO; 1368 if (bp->b_vp) 1369 brelvp(bp); 1370 } 1371 1372 /* 1373 * Check to see if a block is currently memory resident. 1374 */ 1375 struct buf * 1376 gbincore(struct vnode * vp, daddr_t blkno) 1377 { 1378 struct buf *bp; 1379 struct bufhashhdr *bh; 1380 1381 bh = bufhash(vp, blkno); 1382 1383 /* Search hash chain */ 1384 LIST_FOREACH(bp, bh, b_hash) { 1385 /* hit */ 1386 if (bp->b_vp == vp && bp->b_lblkno == blkno && 1387 (bp->b_flags & B_INVAL) == 0) { 1388 break; 1389 } 1390 } 1391 return (bp); 1392 } 1393 1394 /* 1395 * vfs_bio_awrite: 1396 * 1397 * Implement clustered async writes for clearing out B_DELWRI buffers. 1398 * This is much better then the old way of writing only one buffer at 1399 * a time. Note that we may not be presented with the buffers in the 1400 * correct order, so we search for the cluster in both directions. 1401 */ 1402 int 1403 vfs_bio_awrite(struct buf * bp) 1404 { 1405 int i; 1406 int j; 1407 daddr_t lblkno = bp->b_lblkno; 1408 struct vnode *vp = bp->b_vp; 1409 int s; 1410 int ncl; 1411 struct buf *bpa; 1412 int nwritten; 1413 int size; 1414 int maxcl; 1415 1416 s = splbio(); 1417 /* 1418 * right now we support clustered writing only to regular files. If 1419 * we find a clusterable block we could be in the middle of a cluster 1420 * rather then at the beginning. 1421 */ 1422 if ((vp->v_type == VREG) && 1423 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1424 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1425 1426 size = vp->v_mount->mnt_stat.f_iosize; 1427 maxcl = MAXPHYS / size; 1428 1429 for (i = 1; i < maxcl; i++) { 1430 if ((bpa = gbincore(vp, lblkno + i)) && 1431 BUF_REFCNT(bpa) == 0 && 1432 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == 1433 (B_DELWRI | B_CLUSTEROK)) && 1434 (bpa->b_bufsize == size)) { 1435 if ((bpa->b_blkno == bpa->b_lblkno) || 1436 (bpa->b_blkno != 1437 bp->b_blkno + ((i * size) >> DEV_BSHIFT))) 1438 break; 1439 } else { 1440 break; 1441 } 1442 } 1443 for (j = 1; i + j <= maxcl && j <= lblkno; j++) { 1444 if ((bpa = gbincore(vp, lblkno - j)) && 1445 BUF_REFCNT(bpa) == 0 && 1446 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == 1447 (B_DELWRI | B_CLUSTEROK)) && 1448 (bpa->b_bufsize == size)) { 1449 if ((bpa->b_blkno == bpa->b_lblkno) || 1450 (bpa->b_blkno != 1451 bp->b_blkno - ((j * size) >> DEV_BSHIFT))) 1452 break; 1453 } else { 1454 break; 1455 } 1456 } 1457 --j; 1458 ncl = i + j; 1459 /* 1460 * this is a possible cluster write 1461 */ 1462 if (ncl != 1) { 1463 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl); 1464 splx(s); 1465 return nwritten; 1466 } 1467 } 1468 1469 BUF_LOCK(bp, LK_EXCLUSIVE); 1470 bremfree(bp); 1471 bp->b_flags |= B_ASYNC; 1472 1473 splx(s); 1474 /* 1475 * default (old) behavior, writing out only one block 1476 * 1477 * XXX returns b_bufsize instead of b_bcount for nwritten? 1478 */ 1479 nwritten = bp->b_bufsize; 1480 (void) BUF_WRITE(bp); 1481 1482 return nwritten; 1483 } 1484 1485 /* 1486 * getnewbuf: 1487 * 1488 * Find and initialize a new buffer header, freeing up existing buffers 1489 * in the bufqueues as necessary. The new buffer is returned locked. 1490 * 1491 * Important: B_INVAL is not set. If the caller wishes to throw the 1492 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1493 * 1494 * We block if: 1495 * We have insufficient buffer headers 1496 * We have insufficient buffer space 1497 * buffer_map is too fragmented ( space reservation fails ) 1498 * If we have to flush dirty buffers ( but we try to avoid this ) 1499 * 1500 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1501 * Instead we ask the buf daemon to do it for us. We attempt to 1502 * avoid piecemeal wakeups of the pageout daemon. 1503 */ 1504 1505 static struct buf * 1506 getnewbuf(int slpflag, int slptimeo, int size, int maxsize) 1507 { 1508 struct buf *bp; 1509 struct buf *nbp; 1510 int defrag = 0; 1511 int nqindex; 1512 static int flushingbufs; 1513 1514 /* 1515 * We can't afford to block since we might be holding a vnode lock, 1516 * which may prevent system daemons from running. We deal with 1517 * low-memory situations by proactively returning memory and running 1518 * async I/O rather then sync I/O. 1519 */ 1520 1521 ++getnewbufcalls; 1522 --getnewbufrestarts; 1523 restart: 1524 ++getnewbufrestarts; 1525 1526 /* 1527 * Setup for scan. If we do not have enough free buffers, 1528 * we setup a degenerate case that immediately fails. Note 1529 * that if we are specially marked process, we are allowed to 1530 * dip into our reserves. 1531 * 1532 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 1533 * 1534 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 1535 * However, there are a number of cases (defragging, reusing, ...) 1536 * where we cannot backup. 1537 */ 1538 nqindex = QUEUE_EMPTYKVA; 1539 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 1540 1541 if (nbp == NULL) { 1542 /* 1543 * If no EMPTYKVA buffers and we are either 1544 * defragging or reusing, locate a CLEAN buffer 1545 * to free or reuse. If bufspace useage is low 1546 * skip this step so we can allocate a new buffer. 1547 */ 1548 if (defrag || bufspace >= lobufspace) { 1549 nqindex = QUEUE_CLEAN; 1550 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 1551 } 1552 1553 /* 1554 * Nada. If we are allowed to allocate an EMPTY 1555 * buffer, go get one. 1556 */ 1557 if (nbp == NULL && defrag == 0 && bufspace < hibufspace) { 1558 nqindex = QUEUE_EMPTY; 1559 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1560 } 1561 } 1562 1563 /* 1564 * Run scan, possibly freeing data and/or kva mappings on the fly 1565 * depending. 1566 */ 1567 1568 while ((bp = nbp) != NULL) { 1569 int qindex = nqindex; 1570 1571 /* 1572 * Calculate next bp ( we can only use it if we do not block 1573 * or do other fancy things ). 1574 */ 1575 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 1576 switch(qindex) { 1577 case QUEUE_EMPTY: 1578 nqindex = QUEUE_EMPTYKVA; 1579 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]))) 1580 break; 1581 /* fall through */ 1582 case QUEUE_EMPTYKVA: 1583 nqindex = QUEUE_CLEAN; 1584 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]))) 1585 break; 1586 /* fall through */ 1587 case QUEUE_CLEAN: 1588 /* 1589 * nbp is NULL. 1590 */ 1591 break; 1592 } 1593 } 1594 1595 /* 1596 * Sanity Checks 1597 */ 1598 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp)); 1599 1600 /* 1601 * Note: we no longer distinguish between VMIO and non-VMIO 1602 * buffers. 1603 */ 1604 1605 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); 1606 1607 /* 1608 * If we are defragging then we need a buffer with 1609 * b_kvasize != 0. XXX this situation should no longer 1610 * occur, if defrag is non-zero the buffer's b_kvasize 1611 * should also be non-zero at this point. XXX 1612 */ 1613 if (defrag && bp->b_kvasize == 0) { 1614 printf("Warning: defrag empty buffer %p\n", bp); 1615 continue; 1616 } 1617 1618 /* 1619 * Start freeing the bp. This is somewhat involved. nbp 1620 * remains valid only for QUEUE_EMPTY[KVA] bp's. 1621 */ 1622 1623 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) 1624 panic("getnewbuf: locked buf"); 1625 bremfree(bp); 1626 1627 if (qindex == QUEUE_CLEAN) { 1628 if (bp->b_flags & B_VMIO) { 1629 bp->b_flags &= ~B_ASYNC; 1630 vfs_vmio_release(bp); 1631 } 1632 if (bp->b_vp) 1633 brelvp(bp); 1634 } 1635 1636 /* 1637 * NOTE: nbp is now entirely invalid. We can only restart 1638 * the scan from this point on. 1639 * 1640 * Get the rest of the buffer freed up. b_kva* is still 1641 * valid after this operation. 1642 */ 1643 1644 if (bp->b_rcred != NOCRED) { 1645 crfree(bp->b_rcred); 1646 bp->b_rcred = NOCRED; 1647 } 1648 if (bp->b_wcred != NOCRED) { 1649 crfree(bp->b_wcred); 1650 bp->b_wcred = NOCRED; 1651 } 1652 if (LIST_FIRST(&bp->b_dep) != NULL) 1653 buf_deallocate(bp); 1654 if (bp->b_xflags & BX_BKGRDINPROG) 1655 panic("losing buffer 3"); 1656 LIST_REMOVE(bp, b_hash); 1657 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1658 1659 if (bp->b_bufsize) 1660 allocbuf(bp, 0); 1661 1662 bp->b_flags = 0; 1663 bp->b_ioflags = 0; 1664 bp->b_xflags = 0; 1665 bp->b_dev = NODEV; 1666 bp->b_vp = NULL; 1667 bp->b_blkno = bp->b_lblkno = 0; 1668 bp->b_offset = NOOFFSET; 1669 bp->b_iodone = 0; 1670 bp->b_error = 0; 1671 bp->b_resid = 0; 1672 bp->b_bcount = 0; 1673 bp->b_npages = 0; 1674 bp->b_dirtyoff = bp->b_dirtyend = 0; 1675 1676 LIST_INIT(&bp->b_dep); 1677 1678 /* 1679 * If we are defragging then free the buffer. 1680 */ 1681 if (defrag) { 1682 bp->b_flags |= B_INVAL; 1683 bfreekva(bp); 1684 brelse(bp); 1685 defrag = 0; 1686 goto restart; 1687 } 1688 1689 if (bufspace >= hibufspace) 1690 flushingbufs = 1; 1691 if (flushingbufs && bp->b_kvasize != 0) { 1692 bp->b_flags |= B_INVAL; 1693 bfreekva(bp); 1694 brelse(bp); 1695 goto restart; 1696 } 1697 if (bufspace < lobufspace) 1698 flushingbufs = 0; 1699 break; 1700 } 1701 1702 /* 1703 * If we exhausted our list, sleep as appropriate. We may have to 1704 * wakeup various daemons and write out some dirty buffers. 1705 * 1706 * Generally we are sleeping due to insufficient buffer space. 1707 */ 1708 1709 if (bp == NULL) { 1710 int flags; 1711 char *waitmsg; 1712 1713 if (defrag) { 1714 flags = VFS_BIO_NEED_BUFSPACE; 1715 waitmsg = "nbufkv"; 1716 } else if (bufspace >= hibufspace) { 1717 waitmsg = "nbufbs"; 1718 flags = VFS_BIO_NEED_BUFSPACE; 1719 } else { 1720 waitmsg = "newbuf"; 1721 flags = VFS_BIO_NEED_ANY; 1722 } 1723 1724 bd_speedup(); /* heeeelp */ 1725 1726 needsbuffer |= flags; 1727 while (needsbuffer & flags) { 1728 if (tsleep(&needsbuffer, (PRIBIO + 4) | slpflag, 1729 waitmsg, slptimeo)) 1730 return (NULL); 1731 } 1732 } else { 1733 /* 1734 * We finally have a valid bp. We aren't quite out of the 1735 * woods, we still have to reserve kva space. In order 1736 * to keep fragmentation sane we only allocate kva in 1737 * BKVASIZE chunks. 1738 */ 1739 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 1740 1741 if (maxsize != bp->b_kvasize) { 1742 vm_offset_t addr = 0; 1743 1744 bfreekva(bp); 1745 1746 if (vm_map_findspace(buffer_map, 1747 vm_map_min(buffer_map), maxsize, &addr)) { 1748 /* 1749 * Uh oh. Buffer map is to fragmented. We 1750 * must defragment the map. 1751 */ 1752 ++bufdefragcnt; 1753 defrag = 1; 1754 bp->b_flags |= B_INVAL; 1755 brelse(bp); 1756 goto restart; 1757 } 1758 if (addr) { 1759 vm_map_insert(buffer_map, NULL, 0, 1760 addr, addr + maxsize, 1761 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT); 1762 1763 bp->b_kvabase = (caddr_t) addr; 1764 bp->b_kvasize = maxsize; 1765 bufspace += bp->b_kvasize; 1766 ++bufreusecnt; 1767 } 1768 } 1769 bp->b_data = bp->b_kvabase; 1770 } 1771 return(bp); 1772 } 1773 1774 /* 1775 * buf_daemon: 1776 * 1777 * buffer flushing daemon. Buffers are normally flushed by the 1778 * update daemon but if it cannot keep up this process starts to 1779 * take the load in an attempt to prevent getnewbuf() from blocking. 1780 */ 1781 1782 static struct proc *bufdaemonproc; 1783 1784 static struct kproc_desc buf_kp = { 1785 "bufdaemon", 1786 buf_daemon, 1787 &bufdaemonproc 1788 }; 1789 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp) 1790 1791 static void 1792 buf_daemon() 1793 { 1794 int s; 1795 1796 mtx_enter(&Giant, MTX_DEF); 1797 1798 /* 1799 * This process needs to be suspended prior to shutdown sync. 1800 */ 1801 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 1802 SHUTDOWN_PRI_LAST); 1803 1804 /* 1805 * This process is allowed to take the buffer cache to the limit 1806 */ 1807 curproc->p_flag |= P_BUFEXHAUST; 1808 s = splbio(); 1809 1810 for (;;) { 1811 kthread_suspend_check(bufdaemonproc); 1812 1813 bd_request = 0; 1814 1815 /* 1816 * Do the flush. Limit the amount of in-transit I/O we 1817 * allow to build up, otherwise we would completely saturate 1818 * the I/O system. Wakeup any waiting processes before we 1819 * normally would so they can run in parallel with our drain. 1820 */ 1821 while (numdirtybuffers > lodirtybuffers) { 1822 if (flushbufqueues() == 0) 1823 break; 1824 waitrunningbufspace(); 1825 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 1826 } 1827 1828 /* 1829 * Only clear bd_request if we have reached our low water 1830 * mark. The buf_daemon normally waits 5 seconds and 1831 * then incrementally flushes any dirty buffers that have 1832 * built up, within reason. 1833 * 1834 * If we were unable to hit our low water mark and couldn't 1835 * find any flushable buffers, we sleep half a second. 1836 * Otherwise we loop immediately. 1837 */ 1838 if (numdirtybuffers <= lodirtybuffers) { 1839 /* 1840 * We reached our low water mark, reset the 1841 * request and sleep until we are needed again. 1842 * The sleep is just so the suspend code works. 1843 */ 1844 bd_request = 0; 1845 tsleep(&bd_request, PVM, "psleep", hz); 1846 } else { 1847 /* 1848 * We couldn't find any flushable dirty buffers but 1849 * still have too many dirty buffers, we 1850 * have to sleep and try again. (rare) 1851 */ 1852 tsleep(&bd_request, PVM, "qsleep", hz / 2); 1853 } 1854 } 1855 } 1856 1857 /* 1858 * flushbufqueues: 1859 * 1860 * Try to flush a buffer in the dirty queue. We must be careful to 1861 * free up B_INVAL buffers instead of write them, which NFS is 1862 * particularly sensitive to. 1863 */ 1864 1865 static int 1866 flushbufqueues(void) 1867 { 1868 struct buf *bp; 1869 int r = 0; 1870 1871 bp = TAILQ_FIRST(&bufqueues[QUEUE_DIRTY]); 1872 1873 while (bp) { 1874 KASSERT((bp->b_flags & B_DELWRI), ("unexpected clean buffer %p", bp)); 1875 if ((bp->b_flags & B_DELWRI) != 0 && 1876 (bp->b_xflags & BX_BKGRDINPROG) == 0) { 1877 if (bp->b_flags & B_INVAL) { 1878 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) 1879 panic("flushbufqueues: locked buf"); 1880 bremfree(bp); 1881 brelse(bp); 1882 ++r; 1883 break; 1884 } 1885 if (LIST_FIRST(&bp->b_dep) != NULL && 1886 (bp->b_flags & B_DEFERRED) == 0 && 1887 buf_countdeps(bp, 0)) { 1888 TAILQ_REMOVE(&bufqueues[QUEUE_DIRTY], 1889 bp, b_freelist); 1890 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], 1891 bp, b_freelist); 1892 bp->b_flags |= B_DEFERRED; 1893 bp = TAILQ_FIRST(&bufqueues[QUEUE_DIRTY]); 1894 continue; 1895 } 1896 vfs_bio_awrite(bp); 1897 ++r; 1898 break; 1899 } 1900 bp = TAILQ_NEXT(bp, b_freelist); 1901 } 1902 return (r); 1903 } 1904 1905 /* 1906 * Check to see if a block is currently memory resident. 1907 */ 1908 struct buf * 1909 incore(struct vnode * vp, daddr_t blkno) 1910 { 1911 struct buf *bp; 1912 1913 int s = splbio(); 1914 bp = gbincore(vp, blkno); 1915 splx(s); 1916 return (bp); 1917 } 1918 1919 /* 1920 * Returns true if no I/O is needed to access the 1921 * associated VM object. This is like incore except 1922 * it also hunts around in the VM system for the data. 1923 */ 1924 1925 int 1926 inmem(struct vnode * vp, daddr_t blkno) 1927 { 1928 vm_object_t obj; 1929 vm_offset_t toff, tinc, size; 1930 vm_page_t m; 1931 vm_ooffset_t off; 1932 1933 if (incore(vp, blkno)) 1934 return 1; 1935 if (vp->v_mount == NULL) 1936 return 0; 1937 if (VOP_GETVOBJECT(vp, &obj) != 0 || (vp->v_flag & VOBJBUF) == 0) 1938 return 0; 1939 1940 size = PAGE_SIZE; 1941 if (size > vp->v_mount->mnt_stat.f_iosize) 1942 size = vp->v_mount->mnt_stat.f_iosize; 1943 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 1944 1945 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 1946 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 1947 if (!m) 1948 return 0; 1949 tinc = size; 1950 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 1951 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 1952 if (vm_page_is_valid(m, 1953 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 1954 return 0; 1955 } 1956 return 1; 1957 } 1958 1959 /* 1960 * vfs_setdirty: 1961 * 1962 * Sets the dirty range for a buffer based on the status of the dirty 1963 * bits in the pages comprising the buffer. 1964 * 1965 * The range is limited to the size of the buffer. 1966 * 1967 * This routine is primarily used by NFS, but is generalized for the 1968 * B_VMIO case. 1969 */ 1970 static void 1971 vfs_setdirty(struct buf *bp) 1972 { 1973 int i; 1974 vm_object_t object; 1975 1976 /* 1977 * Degenerate case - empty buffer 1978 */ 1979 1980 if (bp->b_bufsize == 0) 1981 return; 1982 1983 /* 1984 * We qualify the scan for modified pages on whether the 1985 * object has been flushed yet. The OBJ_WRITEABLE flag 1986 * is not cleared simply by protecting pages off. 1987 */ 1988 1989 if ((bp->b_flags & B_VMIO) == 0) 1990 return; 1991 1992 object = bp->b_pages[0]->object; 1993 1994 if ((object->flags & OBJ_WRITEABLE) && !(object->flags & OBJ_MIGHTBEDIRTY)) 1995 printf("Warning: object %p writeable but not mightbedirty\n", object); 1996 if (!(object->flags & OBJ_WRITEABLE) && (object->flags & OBJ_MIGHTBEDIRTY)) 1997 printf("Warning: object %p mightbedirty but not writeable\n", object); 1998 1999 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) { 2000 vm_offset_t boffset; 2001 vm_offset_t eoffset; 2002 2003 /* 2004 * test the pages to see if they have been modified directly 2005 * by users through the VM system. 2006 */ 2007 for (i = 0; i < bp->b_npages; i++) { 2008 vm_page_flag_clear(bp->b_pages[i], PG_ZERO); 2009 vm_page_test_dirty(bp->b_pages[i]); 2010 } 2011 2012 /* 2013 * Calculate the encompassing dirty range, boffset and eoffset, 2014 * (eoffset - boffset) bytes. 2015 */ 2016 2017 for (i = 0; i < bp->b_npages; i++) { 2018 if (bp->b_pages[i]->dirty) 2019 break; 2020 } 2021 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2022 2023 for (i = bp->b_npages - 1; i >= 0; --i) { 2024 if (bp->b_pages[i]->dirty) { 2025 break; 2026 } 2027 } 2028 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2029 2030 /* 2031 * Fit it to the buffer. 2032 */ 2033 2034 if (eoffset > bp->b_bcount) 2035 eoffset = bp->b_bcount; 2036 2037 /* 2038 * If we have a good dirty range, merge with the existing 2039 * dirty range. 2040 */ 2041 2042 if (boffset < eoffset) { 2043 if (bp->b_dirtyoff > boffset) 2044 bp->b_dirtyoff = boffset; 2045 if (bp->b_dirtyend < eoffset) 2046 bp->b_dirtyend = eoffset; 2047 } 2048 } 2049 } 2050 2051 /* 2052 * getblk: 2053 * 2054 * Get a block given a specified block and offset into a file/device. 2055 * The buffers B_DONE bit will be cleared on return, making it almost 2056 * ready for an I/O initiation. B_INVAL may or may not be set on 2057 * return. The caller should clear B_INVAL prior to initiating a 2058 * READ. 2059 * 2060 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2061 * an existing buffer. 2062 * 2063 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2064 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2065 * and then cleared based on the backing VM. If the previous buffer is 2066 * non-0-sized but invalid, B_CACHE will be cleared. 2067 * 2068 * If getblk() must create a new buffer, the new buffer is returned with 2069 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2070 * case it is returned with B_INVAL clear and B_CACHE set based on the 2071 * backing VM. 2072 * 2073 * getblk() also forces a VOP_BWRITE() for any B_DELWRI buffer whos 2074 * B_CACHE bit is clear. 2075 * 2076 * What this means, basically, is that the caller should use B_CACHE to 2077 * determine whether the buffer is fully valid or not and should clear 2078 * B_INVAL prior to issuing a read. If the caller intends to validate 2079 * the buffer by loading its data area with something, the caller needs 2080 * to clear B_INVAL. If the caller does this without issuing an I/O, 2081 * the caller should set B_CACHE ( as an optimization ), else the caller 2082 * should issue the I/O and biodone() will set B_CACHE if the I/O was 2083 * a write attempt or if it was a successfull read. If the caller 2084 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 2085 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 2086 */ 2087 struct buf * 2088 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo) 2089 { 2090 struct buf *bp; 2091 int s; 2092 struct bufhashhdr *bh; 2093 2094 if (size > MAXBSIZE) 2095 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 2096 2097 s = splbio(); 2098 loop: 2099 /* 2100 * Block if we are low on buffers. Certain processes are allowed 2101 * to completely exhaust the buffer cache. 2102 * 2103 * If this check ever becomes a bottleneck it may be better to 2104 * move it into the else, when gbincore() fails. At the moment 2105 * it isn't a problem. 2106 * 2107 * XXX remove if 0 sections (clean this up after its proven) 2108 */ 2109 if (numfreebuffers == 0) { 2110 if (curproc == idleproc) 2111 return NULL; 2112 needsbuffer |= VFS_BIO_NEED_ANY; 2113 } 2114 2115 if ((bp = gbincore(vp, blkno))) { 2116 /* 2117 * Buffer is in-core. If the buffer is not busy, it must 2118 * be on a queue. 2119 */ 2120 2121 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) { 2122 if (BUF_TIMELOCK(bp, LK_EXCLUSIVE | LK_SLEEPFAIL, 2123 "getblk", slpflag, slptimeo) == ENOLCK) 2124 goto loop; 2125 splx(s); 2126 return (struct buf *) NULL; 2127 } 2128 2129 /* 2130 * The buffer is locked. B_CACHE is cleared if the buffer is 2131 * invalid. Ohterwise, for a non-VMIO buffer, B_CACHE is set 2132 * and for a VMIO buffer B_CACHE is adjusted according to the 2133 * backing VM cache. 2134 */ 2135 if (bp->b_flags & B_INVAL) 2136 bp->b_flags &= ~B_CACHE; 2137 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 2138 bp->b_flags |= B_CACHE; 2139 bremfree(bp); 2140 2141 /* 2142 * check for size inconsistancies for non-VMIO case. 2143 */ 2144 2145 if (bp->b_bcount != size) { 2146 if ((bp->b_flags & B_VMIO) == 0 || 2147 (size > bp->b_kvasize)) { 2148 if (bp->b_flags & B_DELWRI) { 2149 bp->b_flags |= B_NOCACHE; 2150 BUF_WRITE(bp); 2151 } else { 2152 if ((bp->b_flags & B_VMIO) && 2153 (LIST_FIRST(&bp->b_dep) == NULL)) { 2154 bp->b_flags |= B_RELBUF; 2155 brelse(bp); 2156 } else { 2157 bp->b_flags |= B_NOCACHE; 2158 BUF_WRITE(bp); 2159 } 2160 } 2161 goto loop; 2162 } 2163 } 2164 2165 /* 2166 * If the size is inconsistant in the VMIO case, we can resize 2167 * the buffer. This might lead to B_CACHE getting set or 2168 * cleared. If the size has not changed, B_CACHE remains 2169 * unchanged from its previous state. 2170 */ 2171 2172 if (bp->b_bcount != size) 2173 allocbuf(bp, size); 2174 2175 KASSERT(bp->b_offset != NOOFFSET, 2176 ("getblk: no buffer offset")); 2177 2178 /* 2179 * A buffer with B_DELWRI set and B_CACHE clear must 2180 * be committed before we can return the buffer in 2181 * order to prevent the caller from issuing a read 2182 * ( due to B_CACHE not being set ) and overwriting 2183 * it. 2184 * 2185 * Most callers, including NFS and FFS, need this to 2186 * operate properly either because they assume they 2187 * can issue a read if B_CACHE is not set, or because 2188 * ( for example ) an uncached B_DELWRI might loop due 2189 * to softupdates re-dirtying the buffer. In the latter 2190 * case, B_CACHE is set after the first write completes, 2191 * preventing further loops. 2192 */ 2193 2194 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 2195 BUF_WRITE(bp); 2196 goto loop; 2197 } 2198 2199 splx(s); 2200 bp->b_flags &= ~B_DONE; 2201 } else { 2202 /* 2203 * Buffer is not in-core, create new buffer. The buffer 2204 * returned by getnewbuf() is locked. Note that the returned 2205 * buffer is also considered valid (not marked B_INVAL). 2206 */ 2207 int bsize, maxsize, vmio; 2208 off_t offset; 2209 2210 if (vn_isdisk(vp, NULL)) 2211 bsize = DEV_BSIZE; 2212 else if (vp->v_mountedhere) 2213 bsize = vp->v_mountedhere->mnt_stat.f_iosize; 2214 else if (vp->v_mount) 2215 bsize = vp->v_mount->mnt_stat.f_iosize; 2216 else 2217 bsize = size; 2218 2219 offset = (off_t)blkno * bsize; 2220 vmio = (VOP_GETVOBJECT(vp, NULL) == 0) && (vp->v_flag & VOBJBUF); 2221 maxsize = vmio ? size + (offset & PAGE_MASK) : size; 2222 maxsize = imax(maxsize, bsize); 2223 2224 if ((bp = getnewbuf(slpflag, slptimeo, size, maxsize)) == NULL) { 2225 if (slpflag || slptimeo) { 2226 splx(s); 2227 return NULL; 2228 } 2229 goto loop; 2230 } 2231 2232 /* 2233 * This code is used to make sure that a buffer is not 2234 * created while the getnewbuf routine is blocked. 2235 * This can be a problem whether the vnode is locked or not. 2236 * If the buffer is created out from under us, we have to 2237 * throw away the one we just created. There is now window 2238 * race because we are safely running at splbio() from the 2239 * point of the duplicate buffer creation through to here, 2240 * and we've locked the buffer. 2241 */ 2242 if (gbincore(vp, blkno)) { 2243 bp->b_flags |= B_INVAL; 2244 brelse(bp); 2245 goto loop; 2246 } 2247 2248 /* 2249 * Insert the buffer into the hash, so that it can 2250 * be found by incore. 2251 */ 2252 bp->b_blkno = bp->b_lblkno = blkno; 2253 bp->b_offset = offset; 2254 2255 bgetvp(vp, bp); 2256 LIST_REMOVE(bp, b_hash); 2257 bh = bufhash(vp, blkno); 2258 LIST_INSERT_HEAD(bh, bp, b_hash); 2259 2260 /* 2261 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 2262 * buffer size starts out as 0, B_CACHE will be set by 2263 * allocbuf() for the VMIO case prior to it testing the 2264 * backing store for validity. 2265 */ 2266 2267 if (vmio) { 2268 bp->b_flags |= B_VMIO; 2269 #if defined(VFS_BIO_DEBUG) 2270 if (vp->v_type != VREG) 2271 printf("getblk: vmioing file type %d???\n", vp->v_type); 2272 #endif 2273 } else { 2274 bp->b_flags &= ~B_VMIO; 2275 } 2276 2277 allocbuf(bp, size); 2278 2279 splx(s); 2280 bp->b_flags &= ~B_DONE; 2281 } 2282 return (bp); 2283 } 2284 2285 /* 2286 * Get an empty, disassociated buffer of given size. The buffer is initially 2287 * set to B_INVAL. 2288 */ 2289 struct buf * 2290 geteblk(int size) 2291 { 2292 struct buf *bp; 2293 int s; 2294 int maxsize; 2295 2296 maxsize = (size + BKVAMASK) & ~BKVAMASK; 2297 2298 s = splbio(); 2299 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0); 2300 splx(s); 2301 allocbuf(bp, size); 2302 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 2303 return (bp); 2304 } 2305 2306 2307 /* 2308 * This code constitutes the buffer memory from either anonymous system 2309 * memory (in the case of non-VMIO operations) or from an associated 2310 * VM object (in the case of VMIO operations). This code is able to 2311 * resize a buffer up or down. 2312 * 2313 * Note that this code is tricky, and has many complications to resolve 2314 * deadlock or inconsistant data situations. Tread lightly!!! 2315 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 2316 * the caller. Calling this code willy nilly can result in the loss of data. 2317 * 2318 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 2319 * B_CACHE for the non-VMIO case. 2320 */ 2321 2322 int 2323 allocbuf(struct buf *bp, int size) 2324 { 2325 int newbsize, mbsize; 2326 int i; 2327 2328 if (BUF_REFCNT(bp) == 0) 2329 panic("allocbuf: buffer not busy"); 2330 2331 if (bp->b_kvasize < size) 2332 panic("allocbuf: buffer too small"); 2333 2334 if ((bp->b_flags & B_VMIO) == 0) { 2335 caddr_t origbuf; 2336 int origbufsize; 2337 /* 2338 * Just get anonymous memory from the kernel. Don't 2339 * mess with B_CACHE. 2340 */ 2341 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2342 #if !defined(NO_B_MALLOC) 2343 if (bp->b_flags & B_MALLOC) 2344 newbsize = mbsize; 2345 else 2346 #endif 2347 newbsize = round_page(size); 2348 2349 if (newbsize < bp->b_bufsize) { 2350 #if !defined(NO_B_MALLOC) 2351 /* 2352 * malloced buffers are not shrunk 2353 */ 2354 if (bp->b_flags & B_MALLOC) { 2355 if (newbsize) { 2356 bp->b_bcount = size; 2357 } else { 2358 free(bp->b_data, M_BIOBUF); 2359 if (bp->b_bufsize) { 2360 bufmallocspace -= bp->b_bufsize; 2361 bufspacewakeup(); 2362 bp->b_bufsize = 0; 2363 } 2364 bp->b_data = bp->b_kvabase; 2365 bp->b_bcount = 0; 2366 bp->b_flags &= ~B_MALLOC; 2367 } 2368 return 1; 2369 } 2370 #endif 2371 vm_hold_free_pages( 2372 bp, 2373 (vm_offset_t) bp->b_data + newbsize, 2374 (vm_offset_t) bp->b_data + bp->b_bufsize); 2375 } else if (newbsize > bp->b_bufsize) { 2376 #if !defined(NO_B_MALLOC) 2377 /* 2378 * We only use malloced memory on the first allocation. 2379 * and revert to page-allocated memory when the buffer 2380 * grows. 2381 */ 2382 if ( (bufmallocspace < maxbufmallocspace) && 2383 (bp->b_bufsize == 0) && 2384 (mbsize <= PAGE_SIZE/2)) { 2385 2386 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 2387 bp->b_bufsize = mbsize; 2388 bp->b_bcount = size; 2389 bp->b_flags |= B_MALLOC; 2390 bufmallocspace += mbsize; 2391 return 1; 2392 } 2393 #endif 2394 origbuf = NULL; 2395 origbufsize = 0; 2396 #if !defined(NO_B_MALLOC) 2397 /* 2398 * If the buffer is growing on its other-than-first allocation, 2399 * then we revert to the page-allocation scheme. 2400 */ 2401 if (bp->b_flags & B_MALLOC) { 2402 origbuf = bp->b_data; 2403 origbufsize = bp->b_bufsize; 2404 bp->b_data = bp->b_kvabase; 2405 if (bp->b_bufsize) { 2406 bufmallocspace -= bp->b_bufsize; 2407 bufspacewakeup(); 2408 bp->b_bufsize = 0; 2409 } 2410 bp->b_flags &= ~B_MALLOC; 2411 newbsize = round_page(newbsize); 2412 } 2413 #endif 2414 vm_hold_load_pages( 2415 bp, 2416 (vm_offset_t) bp->b_data + bp->b_bufsize, 2417 (vm_offset_t) bp->b_data + newbsize); 2418 #if !defined(NO_B_MALLOC) 2419 if (origbuf) { 2420 bcopy(origbuf, bp->b_data, origbufsize); 2421 free(origbuf, M_BIOBUF); 2422 } 2423 #endif 2424 } 2425 } else { 2426 vm_page_t m; 2427 int desiredpages; 2428 2429 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2430 desiredpages = (size == 0) ? 0 : 2431 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 2432 2433 #if !defined(NO_B_MALLOC) 2434 if (bp->b_flags & B_MALLOC) 2435 panic("allocbuf: VMIO buffer can't be malloced"); 2436 #endif 2437 /* 2438 * Set B_CACHE initially if buffer is 0 length or will become 2439 * 0-length. 2440 */ 2441 if (size == 0 || bp->b_bufsize == 0) 2442 bp->b_flags |= B_CACHE; 2443 2444 if (newbsize < bp->b_bufsize) { 2445 /* 2446 * DEV_BSIZE aligned new buffer size is less then the 2447 * DEV_BSIZE aligned existing buffer size. Figure out 2448 * if we have to remove any pages. 2449 */ 2450 if (desiredpages < bp->b_npages) { 2451 for (i = desiredpages; i < bp->b_npages; i++) { 2452 /* 2453 * the page is not freed here -- it 2454 * is the responsibility of 2455 * vnode_pager_setsize 2456 */ 2457 m = bp->b_pages[i]; 2458 KASSERT(m != bogus_page, 2459 ("allocbuf: bogus page found")); 2460 while (vm_page_sleep_busy(m, TRUE, "biodep")) 2461 ; 2462 2463 bp->b_pages[i] = NULL; 2464 vm_page_unwire(m, 0); 2465 } 2466 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) + 2467 (desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages)); 2468 bp->b_npages = desiredpages; 2469 } 2470 } else if (size > bp->b_bcount) { 2471 /* 2472 * We are growing the buffer, possibly in a 2473 * byte-granular fashion. 2474 */ 2475 struct vnode *vp; 2476 vm_object_t obj; 2477 vm_offset_t toff; 2478 vm_offset_t tinc; 2479 2480 /* 2481 * Step 1, bring in the VM pages from the object, 2482 * allocating them if necessary. We must clear 2483 * B_CACHE if these pages are not valid for the 2484 * range covered by the buffer. 2485 */ 2486 2487 vp = bp->b_vp; 2488 VOP_GETVOBJECT(vp, &obj); 2489 2490 while (bp->b_npages < desiredpages) { 2491 vm_page_t m; 2492 vm_pindex_t pi; 2493 2494 pi = OFF_TO_IDX(bp->b_offset) + bp->b_npages; 2495 if ((m = vm_page_lookup(obj, pi)) == NULL) { 2496 /* 2497 * note: must allocate system pages 2498 * since blocking here could intefere 2499 * with paging I/O, no matter which 2500 * process we are. 2501 */ 2502 m = vm_page_alloc(obj, pi, VM_ALLOC_SYSTEM); 2503 if (m == NULL) { 2504 VM_WAIT; 2505 vm_pageout_deficit += desiredpages - bp->b_npages; 2506 } else { 2507 vm_page_wire(m); 2508 vm_page_wakeup(m); 2509 bp->b_flags &= ~B_CACHE; 2510 bp->b_pages[bp->b_npages] = m; 2511 ++bp->b_npages; 2512 } 2513 continue; 2514 } 2515 2516 /* 2517 * We found a page. If we have to sleep on it, 2518 * retry because it might have gotten freed out 2519 * from under us. 2520 * 2521 * We can only test PG_BUSY here. Blocking on 2522 * m->busy might lead to a deadlock: 2523 * 2524 * vm_fault->getpages->cluster_read->allocbuf 2525 * 2526 */ 2527 2528 if (vm_page_sleep_busy(m, FALSE, "pgtblk")) 2529 continue; 2530 2531 /* 2532 * We have a good page. Should we wakeup the 2533 * page daemon? 2534 */ 2535 if ((curproc != pageproc) && 2536 ((m->queue - m->pc) == PQ_CACHE) && 2537 ((cnt.v_free_count + cnt.v_cache_count) < 2538 (cnt.v_free_min + cnt.v_cache_min))) { 2539 pagedaemon_wakeup(); 2540 } 2541 vm_page_flag_clear(m, PG_ZERO); 2542 vm_page_wire(m); 2543 bp->b_pages[bp->b_npages] = m; 2544 ++bp->b_npages; 2545 } 2546 2547 /* 2548 * Step 2. We've loaded the pages into the buffer, 2549 * we have to figure out if we can still have B_CACHE 2550 * set. Note that B_CACHE is set according to the 2551 * byte-granular range ( bcount and size ), new the 2552 * aligned range ( newbsize ). 2553 * 2554 * The VM test is against m->valid, which is DEV_BSIZE 2555 * aligned. Needless to say, the validity of the data 2556 * needs to also be DEV_BSIZE aligned. Note that this 2557 * fails with NFS if the server or some other client 2558 * extends the file's EOF. If our buffer is resized, 2559 * B_CACHE may remain set! XXX 2560 */ 2561 2562 toff = bp->b_bcount; 2563 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 2564 2565 while ((bp->b_flags & B_CACHE) && toff < size) { 2566 vm_pindex_t pi; 2567 2568 if (tinc > (size - toff)) 2569 tinc = size - toff; 2570 2571 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 2572 PAGE_SHIFT; 2573 2574 vfs_buf_test_cache( 2575 bp, 2576 bp->b_offset, 2577 toff, 2578 tinc, 2579 bp->b_pages[pi] 2580 ); 2581 toff += tinc; 2582 tinc = PAGE_SIZE; 2583 } 2584 2585 /* 2586 * Step 3, fixup the KVM pmap. Remember that 2587 * bp->b_data is relative to bp->b_offset, but 2588 * bp->b_offset may be offset into the first page. 2589 */ 2590 2591 bp->b_data = (caddr_t) 2592 trunc_page((vm_offset_t)bp->b_data); 2593 pmap_qenter( 2594 (vm_offset_t)bp->b_data, 2595 bp->b_pages, 2596 bp->b_npages 2597 ); 2598 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 2599 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 2600 } 2601 } 2602 if (newbsize < bp->b_bufsize) 2603 bufspacewakeup(); 2604 bp->b_bufsize = newbsize; /* actual buffer allocation */ 2605 bp->b_bcount = size; /* requested buffer size */ 2606 return 1; 2607 } 2608 2609 /* 2610 * bufwait: 2611 * 2612 * Wait for buffer I/O completion, returning error status. The buffer 2613 * is left locked and B_DONE on return. B_EINTR is converted into a EINTR 2614 * error and cleared. 2615 */ 2616 int 2617 bufwait(register struct buf * bp) 2618 { 2619 int s; 2620 2621 s = splbio(); 2622 while ((bp->b_flags & B_DONE) == 0) { 2623 if (bp->b_iocmd == BIO_READ) 2624 tsleep(bp, PRIBIO, "biord", 0); 2625 else 2626 tsleep(bp, PRIBIO, "biowr", 0); 2627 } 2628 splx(s); 2629 if (bp->b_flags & B_EINTR) { 2630 bp->b_flags &= ~B_EINTR; 2631 return (EINTR); 2632 } 2633 if (bp->b_ioflags & BIO_ERROR) { 2634 return (bp->b_error ? bp->b_error : EIO); 2635 } else { 2636 return (0); 2637 } 2638 } 2639 2640 /* 2641 * Call back function from struct bio back up to struct buf. 2642 * The corresponding initialization lives in sys/conf.h:DEV_STRATEGY(). 2643 */ 2644 void 2645 bufdonebio(struct bio *bp) 2646 { 2647 bufdone(bp->bio_caller2); 2648 } 2649 2650 /* 2651 * bufdone: 2652 * 2653 * Finish I/O on a buffer, optionally calling a completion function. 2654 * This is usually called from an interrupt so process blocking is 2655 * not allowed. 2656 * 2657 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 2658 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 2659 * assuming B_INVAL is clear. 2660 * 2661 * For the VMIO case, we set B_CACHE if the op was a read and no 2662 * read error occured, or if the op was a write. B_CACHE is never 2663 * set if the buffer is invalid or otherwise uncacheable. 2664 * 2665 * biodone does not mess with B_INVAL, allowing the I/O routine or the 2666 * initiator to leave B_INVAL set to brelse the buffer out of existance 2667 * in the biodone routine. 2668 */ 2669 void 2670 bufdone(struct buf *bp) 2671 { 2672 int s, error; 2673 void (*biodone) __P((struct buf *)); 2674 2675 s = splbio(); 2676 2677 KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp, BUF_REFCNT(bp))); 2678 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 2679 2680 bp->b_flags |= B_DONE; 2681 runningbufwakeup(bp); 2682 2683 if (bp->b_iocmd == BIO_DELETE) { 2684 brelse(bp); 2685 splx(s); 2686 return; 2687 } 2688 2689 if (bp->b_iocmd == BIO_WRITE) { 2690 vwakeup(bp); 2691 } 2692 2693 /* call optional completion function if requested */ 2694 if (bp->b_iodone != NULL) { 2695 biodone = bp->b_iodone; 2696 bp->b_iodone = NULL; 2697 (*biodone) (bp); 2698 splx(s); 2699 return; 2700 } 2701 if (LIST_FIRST(&bp->b_dep) != NULL) 2702 buf_complete(bp); 2703 2704 if (bp->b_flags & B_VMIO) { 2705 int i; 2706 vm_ooffset_t foff; 2707 vm_page_t m; 2708 vm_object_t obj; 2709 int iosize; 2710 struct vnode *vp = bp->b_vp; 2711 2712 error = VOP_GETVOBJECT(vp, &obj); 2713 2714 #if defined(VFS_BIO_DEBUG) 2715 if (vp->v_usecount == 0) { 2716 panic("biodone: zero vnode ref count"); 2717 } 2718 2719 if (error) { 2720 panic("biodone: missing VM object"); 2721 } 2722 2723 if ((vp->v_flag & VOBJBUF) == 0) { 2724 panic("biodone: vnode is not setup for merged cache"); 2725 } 2726 #endif 2727 2728 foff = bp->b_offset; 2729 KASSERT(bp->b_offset != NOOFFSET, 2730 ("biodone: no buffer offset")); 2731 2732 if (error) { 2733 panic("biodone: no object"); 2734 } 2735 #if defined(VFS_BIO_DEBUG) 2736 if (obj->paging_in_progress < bp->b_npages) { 2737 printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n", 2738 obj->paging_in_progress, bp->b_npages); 2739 } 2740 #endif 2741 2742 /* 2743 * Set B_CACHE if the op was a normal read and no error 2744 * occured. B_CACHE is set for writes in the b*write() 2745 * routines. 2746 */ 2747 iosize = bp->b_bcount - bp->b_resid; 2748 if (bp->b_iocmd == BIO_READ && 2749 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 2750 !(bp->b_ioflags & BIO_ERROR)) { 2751 bp->b_flags |= B_CACHE; 2752 } 2753 2754 for (i = 0; i < bp->b_npages; i++) { 2755 int bogusflag = 0; 2756 int resid; 2757 2758 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 2759 if (resid > iosize) 2760 resid = iosize; 2761 2762 /* 2763 * cleanup bogus pages, restoring the originals 2764 */ 2765 m = bp->b_pages[i]; 2766 if (m == bogus_page) { 2767 bogusflag = 1; 2768 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 2769 if (m == NULL) 2770 panic("biodone: page disappeared!"); 2771 bp->b_pages[i] = m; 2772 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 2773 } 2774 #if defined(VFS_BIO_DEBUG) 2775 if (OFF_TO_IDX(foff) != m->pindex) { 2776 printf( 2777 "biodone: foff(%lu)/m->pindex(%d) mismatch\n", 2778 (unsigned long)foff, m->pindex); 2779 } 2780 #endif 2781 2782 /* 2783 * In the write case, the valid and clean bits are 2784 * already changed correctly ( see bdwrite() ), so we 2785 * only need to do this here in the read case. 2786 */ 2787 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 2788 vfs_page_set_valid(bp, foff, i, m); 2789 } 2790 vm_page_flag_clear(m, PG_ZERO); 2791 2792 /* 2793 * when debugging new filesystems or buffer I/O methods, this 2794 * is the most common error that pops up. if you see this, you 2795 * have not set the page busy flag correctly!!! 2796 */ 2797 if (m->busy == 0) { 2798 printf("biodone: page busy < 0, " 2799 "pindex: %d, foff: 0x(%x,%x), " 2800 "resid: %d, index: %d\n", 2801 (int) m->pindex, (int)(foff >> 32), 2802 (int) foff & 0xffffffff, resid, i); 2803 if (!vn_isdisk(vp, NULL)) 2804 printf(" iosize: %ld, lblkno: %d, flags: 0x%lx, npages: %d\n", 2805 bp->b_vp->v_mount->mnt_stat.f_iosize, 2806 (int) bp->b_lblkno, 2807 bp->b_flags, bp->b_npages); 2808 else 2809 printf(" VDEV, lblkno: %d, flags: 0x%lx, npages: %d\n", 2810 (int) bp->b_lblkno, 2811 bp->b_flags, bp->b_npages); 2812 printf(" valid: 0x%x, dirty: 0x%x, wired: %d\n", 2813 m->valid, m->dirty, m->wire_count); 2814 panic("biodone: page busy < 0\n"); 2815 } 2816 vm_page_io_finish(m); 2817 vm_object_pip_subtract(obj, 1); 2818 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2819 iosize -= resid; 2820 } 2821 if (obj) 2822 vm_object_pip_wakeupn(obj, 0); 2823 } 2824 2825 /* 2826 * For asynchronous completions, release the buffer now. The brelse 2827 * will do a wakeup there if necessary - so no need to do a wakeup 2828 * here in the async case. The sync case always needs to do a wakeup. 2829 */ 2830 2831 if (bp->b_flags & B_ASYNC) { 2832 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 2833 brelse(bp); 2834 else 2835 bqrelse(bp); 2836 } else { 2837 wakeup(bp); 2838 } 2839 splx(s); 2840 } 2841 2842 /* 2843 * This routine is called in lieu of iodone in the case of 2844 * incomplete I/O. This keeps the busy status for pages 2845 * consistant. 2846 */ 2847 void 2848 vfs_unbusy_pages(struct buf * bp) 2849 { 2850 int i; 2851 2852 runningbufwakeup(bp); 2853 if (bp->b_flags & B_VMIO) { 2854 struct vnode *vp = bp->b_vp; 2855 vm_object_t obj; 2856 2857 VOP_GETVOBJECT(vp, &obj); 2858 2859 for (i = 0; i < bp->b_npages; i++) { 2860 vm_page_t m = bp->b_pages[i]; 2861 2862 if (m == bogus_page) { 2863 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 2864 if (!m) { 2865 panic("vfs_unbusy_pages: page missing\n"); 2866 } 2867 bp->b_pages[i] = m; 2868 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 2869 } 2870 vm_object_pip_subtract(obj, 1); 2871 vm_page_flag_clear(m, PG_ZERO); 2872 vm_page_io_finish(m); 2873 } 2874 vm_object_pip_wakeupn(obj, 0); 2875 } 2876 } 2877 2878 /* 2879 * vfs_page_set_valid: 2880 * 2881 * Set the valid bits in a page based on the supplied offset. The 2882 * range is restricted to the buffer's size. 2883 * 2884 * This routine is typically called after a read completes. 2885 */ 2886 static void 2887 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m) 2888 { 2889 vm_ooffset_t soff, eoff; 2890 2891 /* 2892 * Start and end offsets in buffer. eoff - soff may not cross a 2893 * page boundry or cross the end of the buffer. The end of the 2894 * buffer, in this case, is our file EOF, not the allocation size 2895 * of the buffer. 2896 */ 2897 soff = off; 2898 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2899 if (eoff > bp->b_offset + bp->b_bcount) 2900 eoff = bp->b_offset + bp->b_bcount; 2901 2902 /* 2903 * Set valid range. This is typically the entire buffer and thus the 2904 * entire page. 2905 */ 2906 if (eoff > soff) { 2907 vm_page_set_validclean( 2908 m, 2909 (vm_offset_t) (soff & PAGE_MASK), 2910 (vm_offset_t) (eoff - soff) 2911 ); 2912 } 2913 } 2914 2915 /* 2916 * This routine is called before a device strategy routine. 2917 * It is used to tell the VM system that paging I/O is in 2918 * progress, and treat the pages associated with the buffer 2919 * almost as being PG_BUSY. Also the object paging_in_progress 2920 * flag is handled to make sure that the object doesn't become 2921 * inconsistant. 2922 * 2923 * Since I/O has not been initiated yet, certain buffer flags 2924 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 2925 * and should be ignored. 2926 */ 2927 void 2928 vfs_busy_pages(struct buf * bp, int clear_modify) 2929 { 2930 int i, bogus; 2931 2932 bp->b_runningbufspace = bp->b_bufsize; 2933 runningbufspace += bp->b_runningbufspace; 2934 2935 if (bp->b_flags & B_VMIO) { 2936 struct vnode *vp = bp->b_vp; 2937 vm_object_t obj; 2938 vm_ooffset_t foff; 2939 2940 VOP_GETVOBJECT(vp, &obj); 2941 foff = bp->b_offset; 2942 KASSERT(bp->b_offset != NOOFFSET, 2943 ("vfs_busy_pages: no buffer offset")); 2944 vfs_setdirty(bp); 2945 2946 retry: 2947 for (i = 0; i < bp->b_npages; i++) { 2948 vm_page_t m = bp->b_pages[i]; 2949 if (vm_page_sleep_busy(m, FALSE, "vbpage")) 2950 goto retry; 2951 } 2952 2953 bogus = 0; 2954 for (i = 0; i < bp->b_npages; i++) { 2955 vm_page_t m = bp->b_pages[i]; 2956 2957 vm_page_flag_clear(m, PG_ZERO); 2958 if ((bp->b_flags & B_CLUSTER) == 0) { 2959 vm_object_pip_add(obj, 1); 2960 vm_page_io_start(m); 2961 } 2962 2963 /* 2964 * When readying a buffer for a read ( i.e 2965 * clear_modify == 0 ), it is important to do 2966 * bogus_page replacement for valid pages in 2967 * partially instantiated buffers. Partially 2968 * instantiated buffers can, in turn, occur when 2969 * reconstituting a buffer from its VM backing store 2970 * base. We only have to do this if B_CACHE is 2971 * clear ( which causes the I/O to occur in the 2972 * first place ). The replacement prevents the read 2973 * I/O from overwriting potentially dirty VM-backed 2974 * pages. XXX bogus page replacement is, uh, bogus. 2975 * It may not work properly with small-block devices. 2976 * We need to find a better way. 2977 */ 2978 2979 vm_page_protect(m, VM_PROT_NONE); 2980 if (clear_modify) 2981 vfs_page_set_valid(bp, foff, i, m); 2982 else if (m->valid == VM_PAGE_BITS_ALL && 2983 (bp->b_flags & B_CACHE) == 0) { 2984 bp->b_pages[i] = bogus_page; 2985 bogus++; 2986 } 2987 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2988 } 2989 if (bogus) 2990 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 2991 } 2992 } 2993 2994 /* 2995 * Tell the VM system that the pages associated with this buffer 2996 * are clean. This is used for delayed writes where the data is 2997 * going to go to disk eventually without additional VM intevention. 2998 * 2999 * Note that while we only really need to clean through to b_bcount, we 3000 * just go ahead and clean through to b_bufsize. 3001 */ 3002 static void 3003 vfs_clean_pages(struct buf * bp) 3004 { 3005 int i; 3006 3007 if (bp->b_flags & B_VMIO) { 3008 vm_ooffset_t foff; 3009 3010 foff = bp->b_offset; 3011 KASSERT(bp->b_offset != NOOFFSET, 3012 ("vfs_clean_pages: no buffer offset")); 3013 for (i = 0; i < bp->b_npages; i++) { 3014 vm_page_t m = bp->b_pages[i]; 3015 vm_ooffset_t noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3016 vm_ooffset_t eoff = noff; 3017 3018 if (eoff > bp->b_offset + bp->b_bufsize) 3019 eoff = bp->b_offset + bp->b_bufsize; 3020 vfs_page_set_valid(bp, foff, i, m); 3021 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3022 foff = noff; 3023 } 3024 } 3025 } 3026 3027 /* 3028 * vfs_bio_set_validclean: 3029 * 3030 * Set the range within the buffer to valid and clean. The range is 3031 * relative to the beginning of the buffer, b_offset. Note that b_offset 3032 * itself may be offset from the beginning of the first page. 3033 */ 3034 3035 void 3036 vfs_bio_set_validclean(struct buf *bp, int base, int size) 3037 { 3038 if (bp->b_flags & B_VMIO) { 3039 int i; 3040 int n; 3041 3042 /* 3043 * Fixup base to be relative to beginning of first page. 3044 * Set initial n to be the maximum number of bytes in the 3045 * first page that can be validated. 3046 */ 3047 3048 base += (bp->b_offset & PAGE_MASK); 3049 n = PAGE_SIZE - (base & PAGE_MASK); 3050 3051 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 3052 vm_page_t m = bp->b_pages[i]; 3053 3054 if (n > size) 3055 n = size; 3056 3057 vm_page_set_validclean(m, base & PAGE_MASK, n); 3058 base += n; 3059 size -= n; 3060 n = PAGE_SIZE; 3061 } 3062 } 3063 } 3064 3065 /* 3066 * vfs_bio_clrbuf: 3067 * 3068 * clear a buffer. This routine essentially fakes an I/O, so we need 3069 * to clear BIO_ERROR and B_INVAL. 3070 * 3071 * Note that while we only theoretically need to clear through b_bcount, 3072 * we go ahead and clear through b_bufsize. 3073 */ 3074 3075 void 3076 vfs_bio_clrbuf(struct buf *bp) { 3077 int i, mask = 0; 3078 caddr_t sa, ea; 3079 if ((bp->b_flags & (B_VMIO | B_MALLOC)) == B_VMIO) { 3080 bp->b_flags &= ~B_INVAL; 3081 bp->b_ioflags &= ~BIO_ERROR; 3082 if( (bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 3083 (bp->b_offset & PAGE_MASK) == 0) { 3084 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 3085 if (((bp->b_pages[0]->flags & PG_ZERO) == 0) && 3086 ((bp->b_pages[0]->valid & mask) != mask)) { 3087 bzero(bp->b_data, bp->b_bufsize); 3088 } 3089 bp->b_pages[0]->valid |= mask; 3090 bp->b_resid = 0; 3091 return; 3092 } 3093 ea = sa = bp->b_data; 3094 for(i=0;i<bp->b_npages;i++,sa=ea) { 3095 int j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; 3096 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); 3097 ea = (caddr_t)(vm_offset_t)ulmin( 3098 (u_long)(vm_offset_t)ea, 3099 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); 3100 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 3101 if ((bp->b_pages[i]->valid & mask) == mask) 3102 continue; 3103 if ((bp->b_pages[i]->valid & mask) == 0) { 3104 if ((bp->b_pages[i]->flags & PG_ZERO) == 0) { 3105 bzero(sa, ea - sa); 3106 } 3107 } else { 3108 for (; sa < ea; sa += DEV_BSIZE, j++) { 3109 if (((bp->b_pages[i]->flags & PG_ZERO) == 0) && 3110 (bp->b_pages[i]->valid & (1<<j)) == 0) 3111 bzero(sa, DEV_BSIZE); 3112 } 3113 } 3114 bp->b_pages[i]->valid |= mask; 3115 vm_page_flag_clear(bp->b_pages[i], PG_ZERO); 3116 } 3117 bp->b_resid = 0; 3118 } else { 3119 clrbuf(bp); 3120 } 3121 } 3122 3123 /* 3124 * vm_hold_load_pages and vm_hold_unload pages get pages into 3125 * a buffers address space. The pages are anonymous and are 3126 * not associated with a file object. 3127 */ 3128 void 3129 vm_hold_load_pages(struct buf * bp, vm_offset_t from, vm_offset_t to) 3130 { 3131 vm_offset_t pg; 3132 vm_page_t p; 3133 int index; 3134 3135 to = round_page(to); 3136 from = round_page(from); 3137 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3138 3139 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3140 3141 tryagain: 3142 3143 /* 3144 * note: must allocate system pages since blocking here 3145 * could intefere with paging I/O, no matter which 3146 * process we are. 3147 */ 3148 p = vm_page_alloc(kernel_object, 3149 ((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 3150 VM_ALLOC_SYSTEM); 3151 if (!p) { 3152 vm_pageout_deficit += (to - from) >> PAGE_SHIFT; 3153 VM_WAIT; 3154 goto tryagain; 3155 } 3156 vm_page_wire(p); 3157 p->valid = VM_PAGE_BITS_ALL; 3158 vm_page_flag_clear(p, PG_ZERO); 3159 pmap_kenter(pg, VM_PAGE_TO_PHYS(p)); 3160 bp->b_pages[index] = p; 3161 vm_page_wakeup(p); 3162 } 3163 bp->b_npages = index; 3164 } 3165 3166 void 3167 vm_hold_free_pages(struct buf * bp, vm_offset_t from, vm_offset_t to) 3168 { 3169 vm_offset_t pg; 3170 vm_page_t p; 3171 int index, newnpages; 3172 3173 from = round_page(from); 3174 to = round_page(to); 3175 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3176 3177 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3178 p = bp->b_pages[index]; 3179 if (p && (index < bp->b_npages)) { 3180 if (p->busy) { 3181 printf("vm_hold_free_pages: blkno: %d, lblkno: %d\n", 3182 bp->b_blkno, bp->b_lblkno); 3183 } 3184 bp->b_pages[index] = NULL; 3185 pmap_kremove(pg); 3186 vm_page_busy(p); 3187 vm_page_unwire(p, 0); 3188 vm_page_free(p); 3189 } 3190 } 3191 bp->b_npages = newnpages; 3192 } 3193 3194 3195 #include "opt_ddb.h" 3196 #ifdef DDB 3197 #include <ddb/ddb.h> 3198 3199 DB_SHOW_COMMAND(buffer, db_show_buffer) 3200 { 3201 /* get args */ 3202 struct buf *bp = (struct buf *)addr; 3203 3204 if (!have_addr) { 3205 db_printf("usage: show buffer <addr>\n"); 3206 return; 3207 } 3208 3209 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS); 3210 db_printf("b_error = %d, b_bufsize = %ld, b_bcount = %ld, " 3211 "b_resid = %ld\nb_dev = (%d,%d), b_data = %p, " 3212 "b_blkno = %d, b_pblkno = %d\n", 3213 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 3214 major(bp->b_dev), minor(bp->b_dev), 3215 bp->b_data, bp->b_blkno, bp->b_pblkno); 3216 if (bp->b_npages) { 3217 int i; 3218 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 3219 for (i = 0; i < bp->b_npages; i++) { 3220 vm_page_t m; 3221 m = bp->b_pages[i]; 3222 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 3223 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 3224 if ((i + 1) < bp->b_npages) 3225 db_printf(","); 3226 } 3227 db_printf("\n"); 3228 } 3229 } 3230 #endif /* DDB */ 3231