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 runningbufspace; 89 int vmiodirenable = FALSE; 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 maxbdrun; 96 static int needsbuffer; 97 static int numdirtybuffers, 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, hidirtybuffers, CTLFLAG_RW, 105 &hidirtybuffers, 0, ""); 106 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, 107 &numfreebuffers, 0, ""); 108 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, 109 &lofreebuffers, 0, ""); 110 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, 111 &hifreebuffers, 0, ""); 112 SYSCTL_INT(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, 113 &runningbufspace, 0, ""); 114 SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, 115 &maxbufspace, 0, ""); 116 SYSCTL_INT(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, 117 &hibufspace, 0, ""); 118 SYSCTL_INT(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, 119 &lobufspace, 0, ""); 120 SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, 121 &bufspace, 0, ""); 122 SYSCTL_INT(_vfs, OID_AUTO, maxbdrun, CTLFLAG_RW, 123 &maxbdrun, 0, ""); 124 SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, 125 &maxbufmallocspace, 0, ""); 126 SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, 127 &bufmallocspace, 0, ""); 128 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, 129 &getnewbufcalls, 0, ""); 130 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, 131 &getnewbufrestarts, 0, ""); 132 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, 133 &vmiodirenable, 0, ""); 134 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, 135 &bufdefragcnt, 0, ""); 136 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, 137 &buffreekvacnt, 0, ""); 138 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, 139 &bufreusecnt, 0, ""); 140 141 static int bufhashmask; 142 static LIST_HEAD(bufhashhdr, buf) *bufhashtbl, invalhash; 143 struct bqueues bufqueues[BUFFER_QUEUES] = { { 0 } }; 144 char *buf_wmesg = BUF_WMESG; 145 146 extern int vm_swap_size; 147 148 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 149 #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */ 150 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ 151 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 152 153 /* 154 * Buffer hash table code. Note that the logical block scans linearly, which 155 * gives us some L1 cache locality. 156 */ 157 158 static __inline 159 struct bufhashhdr * 160 bufhash(struct vnode *vnp, daddr_t bn) 161 { 162 return(&bufhashtbl[(((uintptr_t)(vnp) >> 7) + (int)bn) & bufhashmask]); 163 } 164 165 /* 166 * numdirtywakeup: 167 * 168 * If someone is blocked due to there being too many dirty buffers, 169 * and numdirtybuffers is now reasonable, wake them up. 170 */ 171 172 static __inline void 173 numdirtywakeup(void) 174 { 175 if (numdirtybuffers < hidirtybuffers) { 176 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) { 177 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH; 178 wakeup(&needsbuffer); 179 } 180 } 181 } 182 183 /* 184 * bufspacewakeup: 185 * 186 * Called when buffer space is potentially available for recovery. 187 * getnewbuf() will block on this flag when it is unable to free 188 * sufficient buffer space. Buffer space becomes recoverable when 189 * bp's get placed back in the queues. 190 */ 191 192 static __inline void 193 bufspacewakeup(void) 194 { 195 /* 196 * If someone is waiting for BUF space, wake them up. Even 197 * though we haven't freed the kva space yet, the waiting 198 * process will be able to now. 199 */ 200 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) { 201 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE; 202 wakeup(&needsbuffer); 203 } 204 } 205 206 /* 207 * bufcountwakeup: 208 * 209 * Called when a buffer has been added to one of the free queues to 210 * account for the buffer and to wakeup anyone waiting for free buffers. 211 * This typically occurs when large amounts of metadata are being handled 212 * by the buffer cache ( else buffer space runs out first, usually ). 213 */ 214 215 static __inline void 216 bufcountwakeup(void) 217 { 218 ++numfreebuffers; 219 if (needsbuffer) { 220 needsbuffer &= ~VFS_BIO_NEED_ANY; 221 if (numfreebuffers >= hifreebuffers) 222 needsbuffer &= ~VFS_BIO_NEED_FREE; 223 wakeup(&needsbuffer); 224 } 225 } 226 227 /* 228 * vfs_buf_test_cache: 229 * 230 * Called when a buffer is extended. This function clears the B_CACHE 231 * bit if the newly extended portion of the buffer does not contain 232 * valid data. 233 */ 234 static __inline__ 235 void 236 vfs_buf_test_cache(struct buf *bp, 237 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 238 vm_page_t m) 239 { 240 if (bp->b_flags & B_CACHE) { 241 int base = (foff + off) & PAGE_MASK; 242 if (vm_page_is_valid(m, base, size) == 0) 243 bp->b_flags &= ~B_CACHE; 244 } 245 } 246 247 static __inline__ 248 void 249 bd_wakeup(int dirtybuflevel) 250 { 251 if (numdirtybuffers >= dirtybuflevel && bd_request == 0) { 252 bd_request = 1; 253 wakeup(&bd_request); 254 } 255 } 256 257 /* 258 * bd_speedup - speedup the buffer cache flushing code 259 */ 260 261 static __inline__ 262 void 263 bd_speedup(void) 264 { 265 bd_wakeup(1); 266 } 267 268 /* 269 * Initialize buffer headers and related structures. 270 */ 271 272 caddr_t 273 bufhashinit(caddr_t vaddr) 274 { 275 /* first, make a null hash table */ 276 for (bufhashmask = 8; bufhashmask < nbuf / 4; bufhashmask <<= 1) 277 ; 278 bufhashtbl = (void *)vaddr; 279 vaddr = vaddr + sizeof(*bufhashtbl) * bufhashmask; 280 --bufhashmask; 281 return(vaddr); 282 } 283 284 void 285 bufinit(void) 286 { 287 struct buf *bp; 288 int i; 289 290 TAILQ_INIT(&bswlist); 291 LIST_INIT(&invalhash); 292 mtx_init(&buftimelock, "buftime lock", MTX_DEF); 293 294 for (i = 0; i <= bufhashmask; i++) 295 LIST_INIT(&bufhashtbl[i]); 296 297 /* next, make a null set of free lists */ 298 for (i = 0; i < BUFFER_QUEUES; i++) 299 TAILQ_INIT(&bufqueues[i]); 300 301 /* finally, initialize each buffer header and stick on empty q */ 302 for (i = 0; i < nbuf; i++) { 303 bp = &buf[i]; 304 bzero(bp, sizeof *bp); 305 bp->b_flags = B_INVAL; /* we're just an empty header */ 306 bp->b_dev = NODEV; 307 bp->b_rcred = NOCRED; 308 bp->b_wcred = NOCRED; 309 bp->b_qindex = QUEUE_EMPTY; 310 bp->b_xflags = 0; 311 LIST_INIT(&bp->b_dep); 312 BUF_LOCKINIT(bp); 313 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 314 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 315 } 316 317 /* 318 * maxbufspace is the absolute maximum amount of buffer space we are 319 * allowed to reserve in KVM and in real terms. The absolute maximum 320 * is nominally used by buf_daemon. hibufspace is the nominal maximum 321 * used by most other processes. The differential is required to 322 * ensure that buf_daemon is able to run when other processes might 323 * be blocked waiting for buffer space. 324 * 325 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 326 * this may result in KVM fragmentation which is not handled optimally 327 * by the system. 328 */ 329 maxbufspace = nbuf * BKVASIZE; 330 hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 331 lobufspace = hibufspace - MAXBSIZE; 332 333 /* 334 * Limit the amount of malloc memory since it is wired permanently into 335 * the kernel space. Even though this is accounted for in the buffer 336 * allocation, we don't want the malloced region to grow uncontrolled. 337 * The malloc scheme improves memory utilization significantly on average 338 * (small) directories. 339 */ 340 maxbufmallocspace = hibufspace / 20; 341 342 /* 343 * Reduce the chance of a deadlock occuring by limiting the number 344 * of delayed-write dirty buffers we allow to stack up. 345 */ 346 hidirtybuffers = nbuf / 4 + 20; 347 numdirtybuffers = 0; 348 /* 349 * To support extreme low-memory systems, make sure hidirtybuffers cannot 350 * eat up all available buffer space. This occurs when our minimum cannot 351 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 352 * BKVASIZE'd (8K) buffers. 353 */ 354 while (hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 355 hidirtybuffers >>= 1; 356 } 357 358 /* 359 * Try to keep the number of free buffers in the specified range, 360 * and give special processes (e.g. like buf_daemon) access to an 361 * emergency reserve. 362 */ 363 lofreebuffers = nbuf / 18 + 5; 364 hifreebuffers = 2 * lofreebuffers; 365 numfreebuffers = nbuf; 366 367 /* 368 * Maximum number of async ops initiated per buf_daemon loop. This is 369 * somewhat of a hack at the moment, we really need to limit ourselves 370 * based on the number of bytes of I/O in-transit that were initiated 371 * from buf_daemon. 372 */ 373 if ((maxbdrun = nswbuf / 4) < 4) 374 maxbdrun = 4; 375 376 bogus_offset = kmem_alloc_pageable(kernel_map, PAGE_SIZE); 377 bogus_page = vm_page_alloc(kernel_object, 378 ((bogus_offset - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 379 VM_ALLOC_NORMAL); 380 cnt.v_wire_count++; 381 382 } 383 384 /* 385 * bfreekva() - free the kva allocation for a buffer. 386 * 387 * Must be called at splbio() or higher as this is the only locking for 388 * buffer_map. 389 * 390 * Since this call frees up buffer space, we call bufspacewakeup(). 391 */ 392 static void 393 bfreekva(struct buf * bp) 394 { 395 if (bp->b_kvasize) { 396 ++buffreekvacnt; 397 bufspace -= bp->b_kvasize; 398 vm_map_delete(buffer_map, 399 (vm_offset_t) bp->b_kvabase, 400 (vm_offset_t) bp->b_kvabase + bp->b_kvasize 401 ); 402 bp->b_kvasize = 0; 403 bufspacewakeup(); 404 } 405 } 406 407 /* 408 * bremfree: 409 * 410 * Remove the buffer from the appropriate free list. 411 */ 412 void 413 bremfree(struct buf * bp) 414 { 415 int s = splbio(); 416 int old_qindex = bp->b_qindex; 417 418 if (bp->b_qindex != QUEUE_NONE) { 419 KASSERT(BUF_REFCNT(bp) == 1, ("bremfree: bp %p not locked",bp)); 420 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 421 bp->b_qindex = QUEUE_NONE; 422 runningbufspace += bp->b_bufsize; 423 } else { 424 if (BUF_REFCNT(bp) <= 1) 425 panic("bremfree: removing a buffer not on a queue"); 426 } 427 428 /* 429 * Fixup numfreebuffers count. If the buffer is invalid or not 430 * delayed-write, and it was on the EMPTY, LRU, or AGE queues, 431 * the buffer was free and we must decrement numfreebuffers. 432 */ 433 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { 434 switch(old_qindex) { 435 case QUEUE_DIRTY: 436 case QUEUE_CLEAN: 437 case QUEUE_EMPTY: 438 case QUEUE_EMPTYKVA: 439 --numfreebuffers; 440 break; 441 default: 442 break; 443 } 444 } 445 splx(s); 446 } 447 448 449 /* 450 * Get a buffer with the specified data. Look in the cache first. We 451 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 452 * is set, the buffer is valid and we do not have to do anything ( see 453 * getblk() ). 454 */ 455 int 456 bread(struct vnode * vp, daddr_t blkno, int size, struct ucred * cred, 457 struct buf ** bpp) 458 { 459 struct buf *bp; 460 461 bp = getblk(vp, blkno, size, 0, 0); 462 *bpp = bp; 463 464 /* if not found in cache, do some I/O */ 465 if ((bp->b_flags & B_CACHE) == 0) { 466 if (curproc != idleproc) 467 curproc->p_stats->p_ru.ru_inblock++; 468 KASSERT(!(bp->b_flags & B_ASYNC), ("bread: illegal async bp %p", bp)); 469 bp->b_iocmd = BIO_READ; 470 bp->b_flags &= ~B_INVAL; 471 bp->b_ioflags &= ~BIO_ERROR; 472 if (bp->b_rcred == NOCRED) { 473 if (cred != NOCRED) 474 crhold(cred); 475 bp->b_rcred = cred; 476 } 477 vfs_busy_pages(bp, 0); 478 VOP_STRATEGY(vp, bp); 479 return (bufwait(bp)); 480 } 481 return (0); 482 } 483 484 /* 485 * Operates like bread, but also starts asynchronous I/O on 486 * read-ahead blocks. We must clear BIO_ERROR and B_INVAL prior 487 * to initiating I/O . If B_CACHE is set, the buffer is valid 488 * and we do not have to do anything. 489 */ 490 int 491 breadn(struct vnode * vp, daddr_t blkno, int size, 492 daddr_t * rablkno, int *rabsize, 493 int cnt, struct ucred * cred, struct buf ** bpp) 494 { 495 struct buf *bp, *rabp; 496 int i; 497 int rv = 0, readwait = 0; 498 499 *bpp = bp = getblk(vp, blkno, size, 0, 0); 500 501 /* if not found in cache, do some I/O */ 502 if ((bp->b_flags & B_CACHE) == 0) { 503 if (curproc != idleproc) 504 curproc->p_stats->p_ru.ru_inblock++; 505 bp->b_iocmd = BIO_READ; 506 bp->b_flags &= ~B_INVAL; 507 bp->b_ioflags &= ~BIO_ERROR; 508 if (bp->b_rcred == NOCRED) { 509 if (cred != NOCRED) 510 crhold(cred); 511 bp->b_rcred = cred; 512 } 513 vfs_busy_pages(bp, 0); 514 VOP_STRATEGY(vp, bp); 515 ++readwait; 516 } 517 518 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 519 if (inmem(vp, *rablkno)) 520 continue; 521 rabp = getblk(vp, *rablkno, *rabsize, 0, 0); 522 523 if ((rabp->b_flags & B_CACHE) == 0) { 524 if (curproc != idleproc) 525 curproc->p_stats->p_ru.ru_inblock++; 526 rabp->b_flags |= B_ASYNC; 527 rabp->b_flags &= ~B_INVAL; 528 rabp->b_ioflags &= ~BIO_ERROR; 529 rabp->b_iocmd = BIO_READ; 530 if (rabp->b_rcred == NOCRED) { 531 if (cred != NOCRED) 532 crhold(cred); 533 rabp->b_rcred = cred; 534 } 535 vfs_busy_pages(rabp, 0); 536 BUF_KERNPROC(rabp); 537 VOP_STRATEGY(vp, rabp); 538 } else { 539 brelse(rabp); 540 } 541 } 542 543 if (readwait) { 544 rv = bufwait(bp); 545 } 546 return (rv); 547 } 548 549 /* 550 * Write, release buffer on completion. (Done by iodone 551 * if async). Do not bother writing anything if the buffer 552 * is invalid. 553 * 554 * Note that we set B_CACHE here, indicating that buffer is 555 * fully valid and thus cacheable. This is true even of NFS 556 * now so we set it generally. This could be set either here 557 * or in biodone() since the I/O is synchronous. We put it 558 * here. 559 */ 560 int 561 bwrite(struct buf * bp) 562 { 563 int oldflags, s; 564 struct buf *newbp; 565 566 if (bp->b_flags & B_INVAL) { 567 brelse(bp); 568 return (0); 569 } 570 571 oldflags = bp->b_flags; 572 573 if (BUF_REFCNT(bp) == 0) 574 panic("bwrite: buffer is not busy???"); 575 s = splbio(); 576 /* 577 * If a background write is already in progress, delay 578 * writing this block if it is asynchronous. Otherwise 579 * wait for the background write to complete. 580 */ 581 if (bp->b_xflags & BX_BKGRDINPROG) { 582 if (bp->b_flags & B_ASYNC) { 583 splx(s); 584 bdwrite(bp); 585 return (0); 586 } 587 bp->b_xflags |= BX_BKGRDWAIT; 588 tsleep(&bp->b_xflags, PRIBIO, "biord", 0); 589 if (bp->b_xflags & BX_BKGRDINPROG) 590 panic("bwrite: still writing"); 591 } 592 593 /* Mark the buffer clean */ 594 bundirty(bp); 595 596 /* 597 * If this buffer is marked for background writing and we 598 * do not have to wait for it, make a copy and write the 599 * copy so as to leave this buffer ready for further use. 600 * 601 * This optimization eats a lot of memory. If we have a page 602 * or buffer shortfall we can't do it. 603 */ 604 if ((bp->b_xflags & BX_BKGRDWRITE) && 605 (bp->b_flags & B_ASYNC) && 606 !vm_page_count_severe() && 607 !buf_dirty_count_severe()) { 608 if (bp->b_iodone != NULL) { 609 printf("bp->b_iodone = %p\n", bp->b_iodone); 610 panic("bwrite: need chained iodone"); 611 } 612 613 /* get a new block */ 614 newbp = geteblk(bp->b_bufsize); 615 616 /* set it to be identical to the old block */ 617 memcpy(newbp->b_data, bp->b_data, bp->b_bufsize); 618 bgetvp(bp->b_vp, newbp); 619 newbp->b_lblkno = bp->b_lblkno; 620 newbp->b_blkno = bp->b_blkno; 621 newbp->b_offset = bp->b_offset; 622 newbp->b_iodone = vfs_backgroundwritedone; 623 newbp->b_flags |= B_ASYNC; 624 newbp->b_flags &= ~B_INVAL; 625 626 /* move over the dependencies */ 627 if (LIST_FIRST(&bp->b_dep) != NULL) 628 buf_movedeps(bp, newbp); 629 630 /* 631 * Initiate write on the copy, release the original to 632 * the B_LOCKED queue so that it cannot go away until 633 * the background write completes. If not locked it could go 634 * away and then be reconstituted while it was being written. 635 * If the reconstituted buffer were written, we could end up 636 * with two background copies being written at the same time. 637 */ 638 bp->b_xflags |= BX_BKGRDINPROG; 639 bp->b_flags |= B_LOCKED; 640 bqrelse(bp); 641 bp = newbp; 642 } 643 644 bp->b_flags &= ~B_DONE; 645 bp->b_ioflags &= ~BIO_ERROR; 646 bp->b_flags |= B_WRITEINPROG | B_CACHE; 647 bp->b_iocmd = BIO_WRITE; 648 649 bp->b_vp->v_numoutput++; 650 vfs_busy_pages(bp, 1); 651 if (curproc != idleproc) 652 curproc->p_stats->p_ru.ru_oublock++; 653 splx(s); 654 if (oldflags & B_ASYNC) 655 BUF_KERNPROC(bp); 656 BUF_STRATEGY(bp); 657 658 if ((oldflags & B_ASYNC) == 0) { 659 int rtval = bufwait(bp); 660 brelse(bp); 661 return (rtval); 662 } 663 664 return (0); 665 } 666 667 /* 668 * Complete a background write started from bwrite. 669 */ 670 static void 671 vfs_backgroundwritedone(bp) 672 struct buf *bp; 673 { 674 struct buf *origbp; 675 676 /* 677 * Find the original buffer that we are writing. 678 */ 679 if ((origbp = gbincore(bp->b_vp, bp->b_lblkno)) == NULL) 680 panic("backgroundwritedone: lost buffer"); 681 /* 682 * Process dependencies then return any unfinished ones. 683 */ 684 if (LIST_FIRST(&bp->b_dep) != NULL) 685 buf_complete(bp); 686 if (LIST_FIRST(&bp->b_dep) != NULL) 687 buf_movedeps(bp, origbp); 688 /* 689 * Clear the BX_BKGRDINPROG flag in the original buffer 690 * and awaken it if it is waiting for the write to complete. 691 * If BX_BKGRDINPROG is not set in the original buffer it must 692 * have been released and re-instantiated - which is not legal. 693 */ 694 KASSERT((origbp->b_xflags & BX_BKGRDINPROG), ("backgroundwritedone: lost buffer2")); 695 origbp->b_xflags &= ~BX_BKGRDINPROG; 696 if (origbp->b_xflags & BX_BKGRDWAIT) { 697 origbp->b_xflags &= ~BX_BKGRDWAIT; 698 wakeup(&origbp->b_xflags); 699 } 700 /* 701 * Clear the B_LOCKED flag and remove it from the locked 702 * queue if it currently resides there. 703 */ 704 origbp->b_flags &= ~B_LOCKED; 705 if (BUF_LOCK(origbp, LK_EXCLUSIVE | LK_NOWAIT) == 0) { 706 bremfree(origbp); 707 bqrelse(origbp); 708 } 709 /* 710 * This buffer is marked B_NOCACHE, so when it is released 711 * by biodone, it will be tossed. We mark it with BIO_READ 712 * to avoid biodone doing a second vwakeup. 713 */ 714 bp->b_flags |= B_NOCACHE; 715 bp->b_iocmd = BIO_READ; 716 bp->b_flags &= ~(B_CACHE | B_DONE); 717 bp->b_iodone = 0; 718 bufdone(bp); 719 } 720 721 /* 722 * Delayed write. (Buffer is marked dirty). Do not bother writing 723 * anything if the buffer is marked invalid. 724 * 725 * Note that since the buffer must be completely valid, we can safely 726 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 727 * biodone() in order to prevent getblk from writing the buffer 728 * out synchronously. 729 */ 730 void 731 bdwrite(struct buf * bp) 732 { 733 if (BUF_REFCNT(bp) == 0) 734 panic("bdwrite: buffer is not busy"); 735 736 if (bp->b_flags & B_INVAL) { 737 brelse(bp); 738 return; 739 } 740 bdirty(bp); 741 742 /* 743 * Set B_CACHE, indicating that the buffer is fully valid. This is 744 * true even of NFS now. 745 */ 746 bp->b_flags |= B_CACHE; 747 748 /* 749 * This bmap keeps the system from needing to do the bmap later, 750 * perhaps when the system is attempting to do a sync. Since it 751 * is likely that the indirect block -- or whatever other datastructure 752 * that the filesystem needs is still in memory now, it is a good 753 * thing to do this. Note also, that if the pageout daemon is 754 * requesting a sync -- there might not be enough memory to do 755 * the bmap then... So, this is important to do. 756 */ 757 if (bp->b_lblkno == bp->b_blkno) { 758 VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 759 } 760 761 /* 762 * Set the *dirty* buffer range based upon the VM system dirty pages. 763 */ 764 vfs_setdirty(bp); 765 766 /* 767 * We need to do this here to satisfy the vnode_pager and the 768 * pageout daemon, so that it thinks that the pages have been 769 * "cleaned". Note that since the pages are in a delayed write 770 * buffer -- the VFS layer "will" see that the pages get written 771 * out on the next sync, or perhaps the cluster will be completed. 772 */ 773 vfs_clean_pages(bp); 774 bqrelse(bp); 775 776 /* 777 * Wakeup the buffer flushing daemon if we have saturated the 778 * buffer cache. 779 */ 780 781 bd_wakeup(hidirtybuffers); 782 783 /* 784 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 785 * due to the softdep code. 786 */ 787 } 788 789 /* 790 * bdirty: 791 * 792 * Turn buffer into delayed write request. We must clear BIO_READ and 793 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 794 * itself to properly update it in the dirty/clean lists. We mark it 795 * B_DONE to ensure that any asynchronization of the buffer properly 796 * clears B_DONE ( else a panic will occur later ). 797 * 798 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 799 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 800 * should only be called if the buffer is known-good. 801 * 802 * Since the buffer is not on a queue, we do not update the numfreebuffers 803 * count. 804 * 805 * Must be called at splbio(). 806 * The buffer must be on QUEUE_NONE. 807 */ 808 void 809 bdirty(bp) 810 struct buf *bp; 811 { 812 KASSERT(bp->b_qindex == QUEUE_NONE, ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 813 bp->b_flags &= ~(B_RELBUF); 814 bp->b_iocmd = BIO_WRITE; 815 816 if ((bp->b_flags & B_DELWRI) == 0) { 817 bp->b_flags |= B_DONE | B_DELWRI; 818 reassignbuf(bp, bp->b_vp); 819 ++numdirtybuffers; 820 bd_wakeup(hidirtybuffers); 821 } 822 } 823 824 /* 825 * bundirty: 826 * 827 * Clear B_DELWRI for buffer. 828 * 829 * Since the buffer is not on a queue, we do not update the numfreebuffers 830 * count. 831 * 832 * Must be called at splbio(). 833 * The buffer must be on QUEUE_NONE. 834 */ 835 836 void 837 bundirty(bp) 838 struct buf *bp; 839 { 840 KASSERT(bp->b_qindex == QUEUE_NONE, ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 841 842 if (bp->b_flags & B_DELWRI) { 843 bp->b_flags &= ~B_DELWRI; 844 reassignbuf(bp, bp->b_vp); 845 --numdirtybuffers; 846 numdirtywakeup(); 847 } 848 /* 849 * Since it is now being written, we can clear its deferred write flag. 850 */ 851 bp->b_flags &= ~B_DEFERRED; 852 } 853 854 /* 855 * bawrite: 856 * 857 * Asynchronous write. Start output on a buffer, but do not wait for 858 * it to complete. The buffer is released when the output completes. 859 * 860 * bwrite() ( or the VOP routine anyway ) is responsible for handling 861 * B_INVAL buffers. Not us. 862 */ 863 void 864 bawrite(struct buf * bp) 865 { 866 bp->b_flags |= B_ASYNC; 867 (void) BUF_WRITE(bp); 868 } 869 870 /* 871 * bowrite: 872 * 873 * Ordered write. Start output on a buffer, and flag it so that the 874 * device will write it in the order it was queued. The buffer is 875 * released when the output completes. bwrite() ( or the VOP routine 876 * anyway ) is responsible for handling B_INVAL buffers. 877 */ 878 int 879 bowrite(struct buf * bp) 880 { 881 bp->b_ioflags |= BIO_ORDERED; 882 bp->b_flags |= B_ASYNC; 883 return (BUF_WRITE(bp)); 884 } 885 886 /* 887 * bwillwrite: 888 * 889 * Called prior to the locking of any vnodes when we are expecting to 890 * write. We do not want to starve the buffer cache with too many 891 * dirty buffers so we block here. By blocking prior to the locking 892 * of any vnodes we attempt to avoid the situation where a locked vnode 893 * prevents the various system daemons from flushing related buffers. 894 */ 895 896 void 897 bwillwrite(void) 898 { 899 int slop = hidirtybuffers / 10; 900 901 if (numdirtybuffers > hidirtybuffers + slop) { 902 int s; 903 904 s = splbio(); 905 while (numdirtybuffers > hidirtybuffers) { 906 bd_wakeup(hidirtybuffers); 907 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH; 908 tsleep(&needsbuffer, (PRIBIO + 4), "flswai", 0); 909 } 910 splx(s); 911 } 912 } 913 914 /* 915 * Return true if we have too many dirty buffers. 916 */ 917 int 918 buf_dirty_count_severe(void) 919 { 920 return(numdirtybuffers >= hidirtybuffers); 921 } 922 923 /* 924 * brelse: 925 * 926 * Release a busy buffer and, if requested, free its resources. The 927 * buffer will be stashed in the appropriate bufqueue[] allowing it 928 * to be accessed later as a cache entity or reused for other purposes. 929 */ 930 void 931 brelse(struct buf * bp) 932 { 933 int s; 934 935 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 936 937 s = splbio(); 938 939 if (bp->b_flags & B_LOCKED) 940 bp->b_ioflags &= ~BIO_ERROR; 941 942 if (bp->b_iocmd == BIO_WRITE && 943 (bp->b_ioflags & BIO_ERROR) && 944 !(bp->b_flags & B_INVAL)) { 945 /* 946 * Failed write, redirty. Must clear BIO_ERROR to prevent 947 * pages from being scrapped. If B_INVAL is set then 948 * this case is not run and the next case is run to 949 * destroy the buffer. B_INVAL can occur if the buffer 950 * is outside the range supported by the underlying device. 951 */ 952 bp->b_ioflags &= ~BIO_ERROR; 953 bdirty(bp); 954 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 955 (bp->b_ioflags & BIO_ERROR) || 956 bp->b_iocmd == BIO_DELETE || (bp->b_bufsize <= 0)) { 957 /* 958 * Either a failed I/O or we were asked to free or not 959 * cache the buffer. 960 */ 961 bp->b_flags |= B_INVAL; 962 if (LIST_FIRST(&bp->b_dep) != NULL) 963 buf_deallocate(bp); 964 if (bp->b_flags & B_DELWRI) { 965 --numdirtybuffers; 966 numdirtywakeup(); 967 } 968 bp->b_flags &= ~(B_DELWRI | B_CACHE); 969 if ((bp->b_flags & B_VMIO) == 0) { 970 if (bp->b_bufsize) 971 allocbuf(bp, 0); 972 if (bp->b_vp) 973 brelvp(bp); 974 } 975 } 976 977 /* 978 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 979 * is called with B_DELWRI set, the underlying pages may wind up 980 * getting freed causing a previous write (bdwrite()) to get 'lost' 981 * because pages associated with a B_DELWRI bp are marked clean. 982 * 983 * We still allow the B_INVAL case to call vfs_vmio_release(), even 984 * if B_DELWRI is set. 985 * 986 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 987 * on pages to return pages to the VM page queues. 988 */ 989 if (bp->b_flags & B_DELWRI) 990 bp->b_flags &= ~B_RELBUF; 991 else if (vm_page_count_severe() && !(bp->b_xflags & BX_BKGRDINPROG)) 992 bp->b_flags |= B_RELBUF; 993 994 /* 995 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 996 * constituted, not even NFS buffers now. Two flags effect this. If 997 * B_INVAL, the struct buf is invalidated but the VM object is kept 998 * around ( i.e. so it is trivial to reconstitute the buffer later ). 999 * 1000 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 1001 * invalidated. BIO_ERROR cannot be set for a failed write unless the 1002 * buffer is also B_INVAL because it hits the re-dirtying code above. 1003 * 1004 * Normally we can do this whether a buffer is B_DELWRI or not. If 1005 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1006 * the commit state and we cannot afford to lose the buffer. If the 1007 * buffer has a background write in progress, we need to keep it 1008 * around to prevent it from being reconstituted and starting a second 1009 * background write. 1010 */ 1011 if ((bp->b_flags & B_VMIO) 1012 && !(bp->b_vp->v_tag == VT_NFS && 1013 !vn_isdisk(bp->b_vp, NULL) && 1014 (bp->b_flags & B_DELWRI)) 1015 ) { 1016 1017 int i, j, resid; 1018 vm_page_t m; 1019 off_t foff; 1020 vm_pindex_t poff; 1021 vm_object_t obj; 1022 struct vnode *vp; 1023 1024 vp = bp->b_vp; 1025 1026 /* 1027 * Get the base offset and length of the buffer. Note that 1028 * for block sizes that are less then PAGE_SIZE, the b_data 1029 * base of the buffer does not represent exactly b_offset and 1030 * neither b_offset nor b_size are necessarily page aligned. 1031 * Instead, the starting position of b_offset is: 1032 * 1033 * b_data + (b_offset & PAGE_MASK) 1034 * 1035 * block sizes less then DEV_BSIZE (usually 512) are not 1036 * supported due to the page granularity bits (m->valid, 1037 * m->dirty, etc...). 1038 * 1039 * See man buf(9) for more information 1040 */ 1041 resid = bp->b_bufsize; 1042 foff = bp->b_offset; 1043 1044 for (i = 0; i < bp->b_npages; i++) { 1045 int had_bogus = 0; 1046 1047 m = bp->b_pages[i]; 1048 vm_page_flag_clear(m, PG_ZERO); 1049 1050 /* 1051 * If we hit a bogus page, fixup *all* the bogus pages 1052 * now. 1053 */ 1054 if (m == bogus_page) { 1055 VOP_GETVOBJECT(vp, &obj); 1056 poff = OFF_TO_IDX(bp->b_offset); 1057 had_bogus = 1; 1058 1059 for (j = i; j < bp->b_npages; j++) { 1060 vm_page_t mtmp; 1061 mtmp = bp->b_pages[j]; 1062 if (mtmp == bogus_page) { 1063 mtmp = vm_page_lookup(obj, poff + j); 1064 if (!mtmp) { 1065 panic("brelse: page missing\n"); 1066 } 1067 bp->b_pages[j] = mtmp; 1068 } 1069 } 1070 1071 if ((bp->b_flags & B_INVAL) == 0) { 1072 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 1073 } 1074 m = bp->b_pages[i]; 1075 } 1076 if ((bp->b_flags & B_NOCACHE) || (bp->b_ioflags & BIO_ERROR)) { 1077 int poffset = foff & PAGE_MASK; 1078 int presid = resid > (PAGE_SIZE - poffset) ? 1079 (PAGE_SIZE - poffset) : resid; 1080 1081 KASSERT(presid >= 0, ("brelse: extra page")); 1082 vm_page_set_invalid(m, poffset, presid); 1083 if (had_bogus) 1084 printf("avoided corruption bug in bogus_page/brelse code\n"); 1085 } 1086 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1087 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1088 } 1089 1090 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1091 vfs_vmio_release(bp); 1092 1093 } else if (bp->b_flags & B_VMIO) { 1094 1095 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1096 vfs_vmio_release(bp); 1097 1098 } 1099 1100 if (bp->b_qindex != QUEUE_NONE) 1101 panic("brelse: free buffer onto another queue???"); 1102 if (BUF_REFCNT(bp) > 1) { 1103 /* do not release to free list */ 1104 BUF_UNLOCK(bp); 1105 splx(s); 1106 return; 1107 } 1108 1109 /* enqueue */ 1110 1111 /* buffers with no memory */ 1112 if (bp->b_bufsize == 0) { 1113 bp->b_flags |= B_INVAL; 1114 bp->b_xflags &= ~BX_BKGRDWRITE; 1115 if (bp->b_xflags & BX_BKGRDINPROG) 1116 panic("losing buffer 1"); 1117 if (bp->b_kvasize) { 1118 bp->b_qindex = QUEUE_EMPTYKVA; 1119 } else { 1120 bp->b_qindex = QUEUE_EMPTY; 1121 } 1122 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1123 LIST_REMOVE(bp, b_hash); 1124 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1125 bp->b_dev = NODEV; 1126 /* buffers with junk contents */ 1127 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || (bp->b_ioflags & BIO_ERROR)) { 1128 bp->b_flags |= B_INVAL; 1129 bp->b_xflags &= ~BX_BKGRDWRITE; 1130 if (bp->b_xflags & BX_BKGRDINPROG) 1131 panic("losing buffer 2"); 1132 bp->b_qindex = QUEUE_CLEAN; 1133 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1134 LIST_REMOVE(bp, b_hash); 1135 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1136 bp->b_dev = NODEV; 1137 1138 /* buffers that are locked */ 1139 } else if (bp->b_flags & B_LOCKED) { 1140 bp->b_qindex = QUEUE_LOCKED; 1141 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LOCKED], bp, b_freelist); 1142 1143 /* remaining buffers */ 1144 } else { 1145 switch(bp->b_flags & (B_DELWRI|B_AGE)) { 1146 case B_DELWRI | B_AGE: 1147 bp->b_qindex = QUEUE_DIRTY; 1148 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_DIRTY], bp, b_freelist); 1149 break; 1150 case B_DELWRI: 1151 bp->b_qindex = QUEUE_DIRTY; 1152 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist); 1153 break; 1154 case B_AGE: 1155 bp->b_qindex = QUEUE_CLEAN; 1156 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1157 break; 1158 default: 1159 bp->b_qindex = QUEUE_CLEAN; 1160 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1161 break; 1162 } 1163 } 1164 1165 /* 1166 * If B_INVAL, clear B_DELWRI. We've already placed the buffer 1167 * on the correct queue. 1168 */ 1169 if ((bp->b_flags & (B_INVAL|B_DELWRI)) == (B_INVAL|B_DELWRI)) { 1170 bp->b_flags &= ~B_DELWRI; 1171 --numdirtybuffers; 1172 numdirtywakeup(); 1173 } 1174 1175 runningbufspace -= bp->b_bufsize; 1176 1177 /* 1178 * Fixup numfreebuffers count. The bp is on an appropriate queue 1179 * unless locked. We then bump numfreebuffers if it is not B_DELWRI. 1180 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1181 * if B_INVAL is set ). 1182 */ 1183 1184 if ((bp->b_flags & B_LOCKED) == 0 && !(bp->b_flags & B_DELWRI)) 1185 bufcountwakeup(); 1186 1187 /* 1188 * Something we can maybe free. 1189 */ 1190 1191 if (bp->b_bufsize || bp->b_kvasize) 1192 bufspacewakeup(); 1193 1194 /* unlock */ 1195 BUF_UNLOCK(bp); 1196 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1197 bp->b_ioflags &= ~BIO_ORDERED; 1198 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1199 panic("brelse: not dirty"); 1200 splx(s); 1201 } 1202 1203 /* 1204 * Release a buffer back to the appropriate queue but do not try to free 1205 * it. The buffer is expected to be used again soon. 1206 * 1207 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1208 * biodone() to requeue an async I/O on completion. It is also used when 1209 * known good buffers need to be requeued but we think we may need the data 1210 * again soon. 1211 */ 1212 void 1213 bqrelse(struct buf * bp) 1214 { 1215 int s; 1216 1217 s = splbio(); 1218 1219 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1220 1221 if (bp->b_qindex != QUEUE_NONE) 1222 panic("bqrelse: free buffer onto another queue???"); 1223 if (BUF_REFCNT(bp) > 1) { 1224 /* do not release to free list */ 1225 BUF_UNLOCK(bp); 1226 splx(s); 1227 return; 1228 } 1229 if (bp->b_flags & B_LOCKED) { 1230 bp->b_ioflags &= ~BIO_ERROR; 1231 bp->b_qindex = QUEUE_LOCKED; 1232 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LOCKED], bp, b_freelist); 1233 /* buffers with stale but valid contents */ 1234 } else if (bp->b_flags & B_DELWRI) { 1235 bp->b_qindex = QUEUE_DIRTY; 1236 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist); 1237 } else if (vm_page_count_severe()) { 1238 /* 1239 * We are too low on memory, we have to try to free the 1240 * buffer (most importantly: the wired pages making up its 1241 * backing store) *now*. 1242 */ 1243 splx(s); 1244 brelse(bp); 1245 return; 1246 } else { 1247 bp->b_qindex = QUEUE_CLEAN; 1248 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1249 } 1250 1251 runningbufspace -= bp->b_bufsize; 1252 1253 if ((bp->b_flags & B_LOCKED) == 0 && 1254 ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI))) { 1255 bufcountwakeup(); 1256 } 1257 1258 /* 1259 * Something we can maybe wakeup 1260 */ 1261 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1262 bufspacewakeup(); 1263 1264 /* unlock */ 1265 BUF_UNLOCK(bp); 1266 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1267 bp->b_ioflags &= ~BIO_ORDERED; 1268 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1269 panic("bqrelse: not dirty"); 1270 splx(s); 1271 } 1272 1273 static void 1274 vfs_vmio_release(bp) 1275 struct buf *bp; 1276 { 1277 int i, s; 1278 vm_page_t m; 1279 1280 s = splvm(); 1281 for (i = 0; i < bp->b_npages; i++) { 1282 m = bp->b_pages[i]; 1283 bp->b_pages[i] = NULL; 1284 /* 1285 * In order to keep page LRU ordering consistent, put 1286 * everything on the inactive queue. 1287 */ 1288 vm_page_unwire(m, 0); 1289 /* 1290 * We don't mess with busy pages, it is 1291 * the responsibility of the process that 1292 * busied the pages to deal with them. 1293 */ 1294 if ((m->flags & PG_BUSY) || (m->busy != 0)) 1295 continue; 1296 1297 if (m->wire_count == 0) { 1298 vm_page_flag_clear(m, PG_ZERO); 1299 /* 1300 * Might as well free the page if we can and it has 1301 * no valid data. 1302 */ 1303 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && m->hold_count == 0) { 1304 vm_page_busy(m); 1305 vm_page_protect(m, VM_PROT_NONE); 1306 vm_page_free(m); 1307 } else if (vm_page_count_severe()) { 1308 vm_page_try_to_cache(m); 1309 } 1310 } 1311 } 1312 runningbufspace -= bp->b_bufsize; 1313 splx(s); 1314 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages); 1315 if (bp->b_bufsize) 1316 bufspacewakeup(); 1317 bp->b_npages = 0; 1318 bp->b_bufsize = 0; 1319 bp->b_flags &= ~B_VMIO; 1320 if (bp->b_vp) 1321 brelvp(bp); 1322 } 1323 1324 /* 1325 * Check to see if a block is currently memory resident. 1326 */ 1327 struct buf * 1328 gbincore(struct vnode * vp, daddr_t blkno) 1329 { 1330 struct buf *bp; 1331 struct bufhashhdr *bh; 1332 1333 bh = bufhash(vp, blkno); 1334 1335 /* Search hash chain */ 1336 LIST_FOREACH(bp, bh, b_hash) { 1337 /* hit */ 1338 if (bp->b_vp == vp && bp->b_lblkno == blkno && 1339 (bp->b_flags & B_INVAL) == 0) { 1340 break; 1341 } 1342 } 1343 return (bp); 1344 } 1345 1346 /* 1347 * vfs_bio_awrite: 1348 * 1349 * Implement clustered async writes for clearing out B_DELWRI buffers. 1350 * This is much better then the old way of writing only one buffer at 1351 * a time. Note that we may not be presented with the buffers in the 1352 * correct order, so we search for the cluster in both directions. 1353 */ 1354 int 1355 vfs_bio_awrite(struct buf * bp) 1356 { 1357 int i; 1358 int j; 1359 daddr_t lblkno = bp->b_lblkno; 1360 struct vnode *vp = bp->b_vp; 1361 int s; 1362 int ncl; 1363 struct buf *bpa; 1364 int nwritten; 1365 int size; 1366 int maxcl; 1367 1368 s = splbio(); 1369 /* 1370 * right now we support clustered writing only to regular files. If 1371 * we find a clusterable block we could be in the middle of a cluster 1372 * rather then at the beginning. 1373 */ 1374 if ((vp->v_type == VREG) && 1375 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1376 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1377 1378 size = vp->v_mount->mnt_stat.f_iosize; 1379 maxcl = MAXPHYS / size; 1380 1381 for (i = 1; i < maxcl; i++) { 1382 if ((bpa = gbincore(vp, lblkno + i)) && 1383 BUF_REFCNT(bpa) == 0 && 1384 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == 1385 (B_DELWRI | B_CLUSTEROK)) && 1386 (bpa->b_bufsize == size)) { 1387 if ((bpa->b_blkno == bpa->b_lblkno) || 1388 (bpa->b_blkno != 1389 bp->b_blkno + ((i * size) >> DEV_BSHIFT))) 1390 break; 1391 } else { 1392 break; 1393 } 1394 } 1395 for (j = 1; i + j <= maxcl && j <= lblkno; j++) { 1396 if ((bpa = gbincore(vp, lblkno - j)) && 1397 BUF_REFCNT(bpa) == 0 && 1398 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == 1399 (B_DELWRI | B_CLUSTEROK)) && 1400 (bpa->b_bufsize == size)) { 1401 if ((bpa->b_blkno == bpa->b_lblkno) || 1402 (bpa->b_blkno != 1403 bp->b_blkno - ((j * size) >> DEV_BSHIFT))) 1404 break; 1405 } else { 1406 break; 1407 } 1408 } 1409 --j; 1410 ncl = i + j; 1411 /* 1412 * this is a possible cluster write 1413 */ 1414 if (ncl != 1) { 1415 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl); 1416 splx(s); 1417 return nwritten; 1418 } 1419 } 1420 1421 BUF_LOCK(bp, LK_EXCLUSIVE); 1422 bremfree(bp); 1423 bp->b_flags |= B_ASYNC; 1424 1425 splx(s); 1426 /* 1427 * default (old) behavior, writing out only one block 1428 * 1429 * XXX returns b_bufsize instead of b_bcount for nwritten? 1430 */ 1431 nwritten = bp->b_bufsize; 1432 (void) BUF_WRITE(bp); 1433 1434 return nwritten; 1435 } 1436 1437 /* 1438 * getnewbuf: 1439 * 1440 * Find and initialize a new buffer header, freeing up existing buffers 1441 * in the bufqueues as necessary. The new buffer is returned locked. 1442 * 1443 * Important: B_INVAL is not set. If the caller wishes to throw the 1444 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1445 * 1446 * We block if: 1447 * We have insufficient buffer headers 1448 * We have insufficient buffer space 1449 * buffer_map is too fragmented ( space reservation fails ) 1450 * If we have to flush dirty buffers ( but we try to avoid this ) 1451 * 1452 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1453 * Instead we ask the buf daemon to do it for us. We attempt to 1454 * avoid piecemeal wakeups of the pageout daemon. 1455 */ 1456 1457 static struct buf * 1458 getnewbuf(int slpflag, int slptimeo, int size, int maxsize) 1459 { 1460 struct buf *bp; 1461 struct buf *nbp; 1462 int defrag = 0; 1463 int nqindex; 1464 static int flushingbufs; 1465 1466 /* 1467 * We can't afford to block since we might be holding a vnode lock, 1468 * which may prevent system daemons from running. We deal with 1469 * low-memory situations by proactively returning memory and running 1470 * async I/O rather then sync I/O. 1471 */ 1472 1473 ++getnewbufcalls; 1474 --getnewbufrestarts; 1475 restart: 1476 ++getnewbufrestarts; 1477 1478 /* 1479 * Setup for scan. If we do not have enough free buffers, 1480 * we setup a degenerate case that immediately fails. Note 1481 * that if we are specially marked process, we are allowed to 1482 * dip into our reserves. 1483 * 1484 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 1485 * 1486 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 1487 * However, there are a number of cases (defragging, reusing, ...) 1488 * where we cannot backup. 1489 */ 1490 nqindex = QUEUE_EMPTYKVA; 1491 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 1492 1493 if (nbp == NULL) { 1494 /* 1495 * If no EMPTYKVA buffers and we are either 1496 * defragging or reusing, locate a CLEAN buffer 1497 * to free or reuse. If bufspace useage is low 1498 * skip this step so we can allocate a new buffer. 1499 */ 1500 if (defrag || bufspace >= lobufspace) { 1501 nqindex = QUEUE_CLEAN; 1502 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 1503 } 1504 1505 /* 1506 * Nada. If we are allowed to allocate an EMPTY 1507 * buffer, go get one. 1508 */ 1509 if (nbp == NULL && defrag == 0 && bufspace < hibufspace) { 1510 nqindex = QUEUE_EMPTY; 1511 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1512 } 1513 } 1514 1515 /* 1516 * Run scan, possibly freeing data and/or kva mappings on the fly 1517 * depending. 1518 */ 1519 1520 while ((bp = nbp) != NULL) { 1521 int qindex = nqindex; 1522 1523 /* 1524 * Calculate next bp ( we can only use it if we do not block 1525 * or do other fancy things ). 1526 */ 1527 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 1528 switch(qindex) { 1529 case QUEUE_EMPTY: 1530 nqindex = QUEUE_EMPTYKVA; 1531 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]))) 1532 break; 1533 /* fall through */ 1534 case QUEUE_EMPTYKVA: 1535 nqindex = QUEUE_CLEAN; 1536 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]))) 1537 break; 1538 /* fall through */ 1539 case QUEUE_CLEAN: 1540 /* 1541 * nbp is NULL. 1542 */ 1543 break; 1544 } 1545 } 1546 1547 /* 1548 * Sanity Checks 1549 */ 1550 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp)); 1551 1552 /* 1553 * Note: we no longer distinguish between VMIO and non-VMIO 1554 * buffers. 1555 */ 1556 1557 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); 1558 1559 /* 1560 * If we are defragging then we need a buffer with 1561 * b_kvasize != 0. XXX this situation should no longer 1562 * occur, if defrag is non-zero the buffer's b_kvasize 1563 * should also be non-zero at this point. XXX 1564 */ 1565 if (defrag && bp->b_kvasize == 0) { 1566 printf("Warning: defrag empty buffer %p\n", bp); 1567 continue; 1568 } 1569 1570 /* 1571 * Start freeing the bp. This is somewhat involved. nbp 1572 * remains valid only for QUEUE_EMPTY[KVA] bp's. 1573 */ 1574 1575 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) 1576 panic("getnewbuf: locked buf"); 1577 bremfree(bp); 1578 1579 if (qindex == QUEUE_CLEAN) { 1580 if (bp->b_flags & B_VMIO) { 1581 bp->b_flags &= ~B_ASYNC; 1582 vfs_vmio_release(bp); 1583 } 1584 if (bp->b_vp) 1585 brelvp(bp); 1586 } 1587 1588 /* 1589 * NOTE: nbp is now entirely invalid. We can only restart 1590 * the scan from this point on. 1591 * 1592 * Get the rest of the buffer freed up. b_kva* is still 1593 * valid after this operation. 1594 */ 1595 1596 if (bp->b_rcred != NOCRED) { 1597 crfree(bp->b_rcred); 1598 bp->b_rcred = NOCRED; 1599 } 1600 if (bp->b_wcred != NOCRED) { 1601 crfree(bp->b_wcred); 1602 bp->b_wcred = NOCRED; 1603 } 1604 if (LIST_FIRST(&bp->b_dep) != NULL) 1605 buf_deallocate(bp); 1606 if (bp->b_xflags & BX_BKGRDINPROG) 1607 panic("losing buffer 3"); 1608 LIST_REMOVE(bp, b_hash); 1609 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1610 1611 if (bp->b_bufsize) 1612 allocbuf(bp, 0); 1613 1614 bp->b_flags = 0; 1615 bp->b_ioflags = 0; 1616 bp->b_xflags = 0; 1617 bp->b_dev = NODEV; 1618 bp->b_vp = NULL; 1619 bp->b_blkno = bp->b_lblkno = 0; 1620 bp->b_offset = NOOFFSET; 1621 bp->b_iodone = 0; 1622 bp->b_error = 0; 1623 bp->b_resid = 0; 1624 bp->b_bcount = 0; 1625 bp->b_npages = 0; 1626 bp->b_dirtyoff = bp->b_dirtyend = 0; 1627 1628 LIST_INIT(&bp->b_dep); 1629 1630 /* 1631 * If we are defragging then free the buffer. 1632 */ 1633 if (defrag) { 1634 bp->b_flags |= B_INVAL; 1635 bfreekva(bp); 1636 brelse(bp); 1637 defrag = 0; 1638 goto restart; 1639 } 1640 1641 if (bufspace >= hibufspace) 1642 flushingbufs = 1; 1643 if (flushingbufs && bp->b_kvasize != 0) { 1644 bp->b_flags |= B_INVAL; 1645 bfreekva(bp); 1646 brelse(bp); 1647 goto restart; 1648 } 1649 if (bufspace < lobufspace) 1650 flushingbufs = 0; 1651 break; 1652 } 1653 1654 /* 1655 * If we exhausted our list, sleep as appropriate. We may have to 1656 * wakeup various daemons and write out some dirty buffers. 1657 * 1658 * Generally we are sleeping due to insufficient buffer space. 1659 */ 1660 1661 if (bp == NULL) { 1662 int flags; 1663 char *waitmsg; 1664 1665 if (defrag) { 1666 flags = VFS_BIO_NEED_BUFSPACE; 1667 waitmsg = "nbufkv"; 1668 } else if (bufspace >= hibufspace) { 1669 waitmsg = "nbufbs"; 1670 flags = VFS_BIO_NEED_BUFSPACE; 1671 } else { 1672 waitmsg = "newbuf"; 1673 flags = VFS_BIO_NEED_ANY; 1674 } 1675 1676 bd_speedup(); /* heeeelp */ 1677 1678 needsbuffer |= flags; 1679 while (needsbuffer & flags) { 1680 if (tsleep(&needsbuffer, (PRIBIO + 4) | slpflag, 1681 waitmsg, slptimeo)) 1682 return (NULL); 1683 } 1684 } else { 1685 /* 1686 * We finally have a valid bp. We aren't quite out of the 1687 * woods, we still have to reserve kva space. In order 1688 * to keep fragmentation sane we only allocate kva in 1689 * BKVASIZE chunks. 1690 */ 1691 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 1692 1693 if (maxsize != bp->b_kvasize) { 1694 vm_offset_t addr = 0; 1695 1696 bfreekva(bp); 1697 1698 if (vm_map_findspace(buffer_map, 1699 vm_map_min(buffer_map), maxsize, &addr)) { 1700 /* 1701 * Uh oh. Buffer map is to fragmented. We 1702 * must defragment the map. 1703 */ 1704 ++bufdefragcnt; 1705 defrag = 1; 1706 bp->b_flags |= B_INVAL; 1707 brelse(bp); 1708 goto restart; 1709 } 1710 if (addr) { 1711 vm_map_insert(buffer_map, NULL, 0, 1712 addr, addr + maxsize, 1713 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT); 1714 1715 bp->b_kvabase = (caddr_t) addr; 1716 bp->b_kvasize = maxsize; 1717 bufspace += bp->b_kvasize; 1718 ++bufreusecnt; 1719 } 1720 } 1721 bp->b_data = bp->b_kvabase; 1722 } 1723 return(bp); 1724 } 1725 1726 #if 0 1727 /* 1728 * waitfreebuffers: 1729 * 1730 * Wait for sufficient free buffers. Only called from normal processes. 1731 */ 1732 1733 static void 1734 waitfreebuffers(int slpflag, int slptimeo) 1735 { 1736 while (numfreebuffers < hifreebuffers) { 1737 if (numfreebuffers >= hifreebuffers) 1738 break; 1739 needsbuffer |= VFS_BIO_NEED_FREE; 1740 if (tsleep(&needsbuffer, (PRIBIO + 4)|slpflag, "biofre", slptimeo)) 1741 break; 1742 } 1743 } 1744 1745 #endif 1746 1747 /* 1748 * buf_daemon: 1749 * 1750 * buffer flushing daemon. Buffers are normally flushed by the 1751 * update daemon but if it cannot keep up this process starts to 1752 * take the load in an attempt to prevent getnewbuf() from blocking. 1753 */ 1754 1755 static struct proc *bufdaemonproc; 1756 static int bd_interval; 1757 static int bd_flushto; 1758 static int bd_flushinc; 1759 1760 static struct kproc_desc buf_kp = { 1761 "bufdaemon", 1762 buf_daemon, 1763 &bufdaemonproc 1764 }; 1765 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp) 1766 1767 static void 1768 buf_daemon() 1769 { 1770 int s; 1771 1772 mtx_enter(&Giant, MTX_DEF); 1773 1774 /* 1775 * This process needs to be suspended prior to shutdown sync. 1776 */ 1777 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc, bufdaemonproc, 1778 SHUTDOWN_PRI_LAST); 1779 1780 /* 1781 * This process is allowed to take the buffer cache to the limit 1782 */ 1783 curproc->p_flag |= P_BUFEXHAUST; 1784 s = splbio(); 1785 1786 bd_interval = 5 * hz; /* dynamically adjusted */ 1787 bd_flushto = hidirtybuffers; /* dynamically adjusted */ 1788 bd_flushinc = 1; 1789 1790 for (;;) { 1791 kproc_suspend_loop(bufdaemonproc); 1792 1793 bd_request = 0; 1794 1795 /* 1796 * Do the flush. Limit the number of buffers we flush in one 1797 * go. The failure condition occurs when processes are writing 1798 * buffers faster then we can dispose of them. In this case 1799 * we may be flushing so often that the previous set of flushes 1800 * have not had time to complete, causing us to run out of 1801 * physical buffers and block. 1802 */ 1803 { 1804 int runcount = maxbdrun; 1805 1806 while (numdirtybuffers > bd_flushto && runcount) { 1807 --runcount; 1808 if (flushbufqueues() == 0) 1809 break; 1810 } 1811 } 1812 1813 if (bd_request || 1814 tsleep(&bd_request, PVM, "psleep", bd_interval) == 0) { 1815 /* 1816 * Another request is pending or we were woken up 1817 * without timing out. Flush more. 1818 */ 1819 --bd_flushto; 1820 if (bd_flushto >= numdirtybuffers - 5) { 1821 bd_flushto = numdirtybuffers - 10; 1822 bd_flushinc = 1; 1823 } 1824 if (bd_flushto < 2) 1825 bd_flushto = 2; 1826 } else { 1827 /* 1828 * We slept and timed out, we can slow down. 1829 */ 1830 bd_flushto += bd_flushinc; 1831 if (bd_flushto > hidirtybuffers) 1832 bd_flushto = hidirtybuffers; 1833 ++bd_flushinc; 1834 if (bd_flushinc > hidirtybuffers / 20 + 1) 1835 bd_flushinc = hidirtybuffers / 20 + 1; 1836 } 1837 1838 /* 1839 * Set the interval on a linear scale based on hidirtybuffers 1840 * with a maximum frequency of 1/10 second. 1841 */ 1842 bd_interval = bd_flushto * 5 * hz / hidirtybuffers; 1843 if (bd_interval < hz / 10) 1844 bd_interval = hz / 10; 1845 } 1846 } 1847 1848 /* 1849 * flushbufqueues: 1850 * 1851 * Try to flush a buffer in the dirty queue. We must be careful to 1852 * free up B_INVAL buffers instead of write them, which NFS is 1853 * particularly sensitive to. 1854 */ 1855 1856 static int 1857 flushbufqueues(void) 1858 { 1859 struct buf *bp; 1860 int r = 0; 1861 1862 bp = TAILQ_FIRST(&bufqueues[QUEUE_DIRTY]); 1863 1864 while (bp) { 1865 KASSERT((bp->b_flags & B_DELWRI), ("unexpected clean buffer %p", bp)); 1866 if ((bp->b_flags & B_DELWRI) != 0 && 1867 (bp->b_xflags & BX_BKGRDINPROG) == 0) { 1868 if (bp->b_flags & B_INVAL) { 1869 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) 1870 panic("flushbufqueues: locked buf"); 1871 bremfree(bp); 1872 brelse(bp); 1873 ++r; 1874 break; 1875 } 1876 if (LIST_FIRST(&bp->b_dep) != NULL && 1877 (bp->b_flags & B_DEFERRED) == 0 && 1878 buf_countdeps(bp, 0)) { 1879 TAILQ_REMOVE(&bufqueues[QUEUE_DIRTY], 1880 bp, b_freelist); 1881 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], 1882 bp, b_freelist); 1883 bp->b_flags |= B_DEFERRED; 1884 bp = TAILQ_FIRST(&bufqueues[QUEUE_DIRTY]); 1885 continue; 1886 } 1887 vfs_bio_awrite(bp); 1888 ++r; 1889 break; 1890 } 1891 bp = TAILQ_NEXT(bp, b_freelist); 1892 } 1893 return (r); 1894 } 1895 1896 /* 1897 * Check to see if a block is currently memory resident. 1898 */ 1899 struct buf * 1900 incore(struct vnode * vp, daddr_t blkno) 1901 { 1902 struct buf *bp; 1903 1904 int s = splbio(); 1905 bp = gbincore(vp, blkno); 1906 splx(s); 1907 return (bp); 1908 } 1909 1910 /* 1911 * Returns true if no I/O is needed to access the 1912 * associated VM object. This is like incore except 1913 * it also hunts around in the VM system for the data. 1914 */ 1915 1916 int 1917 inmem(struct vnode * vp, daddr_t blkno) 1918 { 1919 vm_object_t obj; 1920 vm_offset_t toff, tinc, size; 1921 vm_page_t m; 1922 vm_ooffset_t off; 1923 1924 if (incore(vp, blkno)) 1925 return 1; 1926 if (vp->v_mount == NULL) 1927 return 0; 1928 if (VOP_GETVOBJECT(vp, &obj) != 0 || (vp->v_flag & VOBJBUF) == 0) 1929 return 0; 1930 1931 size = PAGE_SIZE; 1932 if (size > vp->v_mount->mnt_stat.f_iosize) 1933 size = vp->v_mount->mnt_stat.f_iosize; 1934 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 1935 1936 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 1937 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 1938 if (!m) 1939 return 0; 1940 tinc = size; 1941 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 1942 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 1943 if (vm_page_is_valid(m, 1944 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 1945 return 0; 1946 } 1947 return 1; 1948 } 1949 1950 /* 1951 * vfs_setdirty: 1952 * 1953 * Sets the dirty range for a buffer based on the status of the dirty 1954 * bits in the pages comprising the buffer. 1955 * 1956 * The range is limited to the size of the buffer. 1957 * 1958 * This routine is primarily used by NFS, but is generalized for the 1959 * B_VMIO case. 1960 */ 1961 static void 1962 vfs_setdirty(struct buf *bp) 1963 { 1964 int i; 1965 vm_object_t object; 1966 1967 /* 1968 * Degenerate case - empty buffer 1969 */ 1970 1971 if (bp->b_bufsize == 0) 1972 return; 1973 1974 /* 1975 * We qualify the scan for modified pages on whether the 1976 * object has been flushed yet. The OBJ_WRITEABLE flag 1977 * is not cleared simply by protecting pages off. 1978 */ 1979 1980 if ((bp->b_flags & B_VMIO) == 0) 1981 return; 1982 1983 object = bp->b_pages[0]->object; 1984 1985 if ((object->flags & OBJ_WRITEABLE) && !(object->flags & OBJ_MIGHTBEDIRTY)) 1986 printf("Warning: object %p writeable but not mightbedirty\n", object); 1987 if (!(object->flags & OBJ_WRITEABLE) && (object->flags & OBJ_MIGHTBEDIRTY)) 1988 printf("Warning: object %p mightbedirty but not writeable\n", object); 1989 1990 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) { 1991 vm_offset_t boffset; 1992 vm_offset_t eoffset; 1993 1994 /* 1995 * test the pages to see if they have been modified directly 1996 * by users through the VM system. 1997 */ 1998 for (i = 0; i < bp->b_npages; i++) { 1999 vm_page_flag_clear(bp->b_pages[i], PG_ZERO); 2000 vm_page_test_dirty(bp->b_pages[i]); 2001 } 2002 2003 /* 2004 * Calculate the encompassing dirty range, boffset and eoffset, 2005 * (eoffset - boffset) bytes. 2006 */ 2007 2008 for (i = 0; i < bp->b_npages; i++) { 2009 if (bp->b_pages[i]->dirty) 2010 break; 2011 } 2012 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2013 2014 for (i = bp->b_npages - 1; i >= 0; --i) { 2015 if (bp->b_pages[i]->dirty) { 2016 break; 2017 } 2018 } 2019 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2020 2021 /* 2022 * Fit it to the buffer. 2023 */ 2024 2025 if (eoffset > bp->b_bcount) 2026 eoffset = bp->b_bcount; 2027 2028 /* 2029 * If we have a good dirty range, merge with the existing 2030 * dirty range. 2031 */ 2032 2033 if (boffset < eoffset) { 2034 if (bp->b_dirtyoff > boffset) 2035 bp->b_dirtyoff = boffset; 2036 if (bp->b_dirtyend < eoffset) 2037 bp->b_dirtyend = eoffset; 2038 } 2039 } 2040 } 2041 2042 /* 2043 * getblk: 2044 * 2045 * Get a block given a specified block and offset into a file/device. 2046 * The buffers B_DONE bit will be cleared on return, making it almost 2047 * ready for an I/O initiation. B_INVAL may or may not be set on 2048 * return. The caller should clear B_INVAL prior to initiating a 2049 * READ. 2050 * 2051 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2052 * an existing buffer. 2053 * 2054 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2055 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2056 * and then cleared based on the backing VM. If the previous buffer is 2057 * non-0-sized but invalid, B_CACHE will be cleared. 2058 * 2059 * If getblk() must create a new buffer, the new buffer is returned with 2060 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2061 * case it is returned with B_INVAL clear and B_CACHE set based on the 2062 * backing VM. 2063 * 2064 * getblk() also forces a VOP_BWRITE() for any B_DELWRI buffer whos 2065 * B_CACHE bit is clear. 2066 * 2067 * What this means, basically, is that the caller should use B_CACHE to 2068 * determine whether the buffer is fully valid or not and should clear 2069 * B_INVAL prior to issuing a read. If the caller intends to validate 2070 * the buffer by loading its data area with something, the caller needs 2071 * to clear B_INVAL. If the caller does this without issuing an I/O, 2072 * the caller should set B_CACHE ( as an optimization ), else the caller 2073 * should issue the I/O and biodone() will set B_CACHE if the I/O was 2074 * a write attempt or if it was a successfull read. If the caller 2075 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 2076 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 2077 */ 2078 struct buf * 2079 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo) 2080 { 2081 struct buf *bp; 2082 int s; 2083 struct bufhashhdr *bh; 2084 2085 if (size > MAXBSIZE) 2086 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 2087 2088 s = splbio(); 2089 loop: 2090 /* 2091 * Block if we are low on buffers. Certain processes are allowed 2092 * to completely exhaust the buffer cache. 2093 * 2094 * If this check ever becomes a bottleneck it may be better to 2095 * move it into the else, when gbincore() fails. At the moment 2096 * it isn't a problem. 2097 * 2098 * XXX remove if 0 sections (clean this up after its proven) 2099 */ 2100 #if 0 2101 if (curproc == idleproc || (curproc->p_flag & P_BUFEXHAUST)) { 2102 #endif 2103 if (numfreebuffers == 0) { 2104 if (curproc == idleproc) 2105 return NULL; 2106 needsbuffer |= VFS_BIO_NEED_ANY; 2107 tsleep(&needsbuffer, (PRIBIO + 4) | slpflag, "newbuf", 2108 slptimeo); 2109 } 2110 #if 0 2111 } else if (numfreebuffers < lofreebuffers) { 2112 waitfreebuffers(slpflag, slptimeo); 2113 } 2114 #endif 2115 2116 if ((bp = gbincore(vp, blkno))) { 2117 /* 2118 * Buffer is in-core. If the buffer is not busy, it must 2119 * be on a queue. 2120 */ 2121 2122 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) { 2123 if (BUF_TIMELOCK(bp, LK_EXCLUSIVE | LK_SLEEPFAIL, 2124 "getblk", slpflag, slptimeo) == ENOLCK) 2125 goto loop; 2126 splx(s); 2127 return (struct buf *) NULL; 2128 } 2129 2130 /* 2131 * The buffer is locked. B_CACHE is cleared if the buffer is 2132 * invalid. Ohterwise, for a non-VMIO buffer, B_CACHE is set 2133 * and for a VMIO buffer B_CACHE is adjusted according to the 2134 * backing VM cache. 2135 */ 2136 if (bp->b_flags & B_INVAL) 2137 bp->b_flags &= ~B_CACHE; 2138 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 2139 bp->b_flags |= B_CACHE; 2140 bremfree(bp); 2141 2142 /* 2143 * check for size inconsistancies for non-VMIO case. 2144 */ 2145 2146 if (bp->b_bcount != size) { 2147 if ((bp->b_flags & B_VMIO) == 0 || 2148 (size > bp->b_kvasize)) { 2149 if (bp->b_flags & B_DELWRI) { 2150 bp->b_flags |= B_NOCACHE; 2151 BUF_WRITE(bp); 2152 } else { 2153 if ((bp->b_flags & B_VMIO) && 2154 (LIST_FIRST(&bp->b_dep) == NULL)) { 2155 bp->b_flags |= B_RELBUF; 2156 brelse(bp); 2157 } else { 2158 bp->b_flags |= B_NOCACHE; 2159 BUF_WRITE(bp); 2160 } 2161 } 2162 goto loop; 2163 } 2164 } 2165 2166 /* 2167 * If the size is inconsistant in the VMIO case, we can resize 2168 * the buffer. This might lead to B_CACHE getting set or 2169 * cleared. If the size has not changed, B_CACHE remains 2170 * unchanged from its previous state. 2171 */ 2172 2173 if (bp->b_bcount != size) 2174 allocbuf(bp, size); 2175 2176 KASSERT(bp->b_offset != NOOFFSET, 2177 ("getblk: no buffer offset")); 2178 2179 /* 2180 * A buffer with B_DELWRI set and B_CACHE clear must 2181 * be committed before we can return the buffer in 2182 * order to prevent the caller from issuing a read 2183 * ( due to B_CACHE not being set ) and overwriting 2184 * it. 2185 * 2186 * Most callers, including NFS and FFS, need this to 2187 * operate properly either because they assume they 2188 * can issue a read if B_CACHE is not set, or because 2189 * ( for example ) an uncached B_DELWRI might loop due 2190 * to softupdates re-dirtying the buffer. In the latter 2191 * case, B_CACHE is set after the first write completes, 2192 * preventing further loops. 2193 */ 2194 2195 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 2196 BUF_WRITE(bp); 2197 goto loop; 2198 } 2199 2200 splx(s); 2201 bp->b_flags &= ~B_DONE; 2202 } else { 2203 /* 2204 * Buffer is not in-core, create new buffer. The buffer 2205 * returned by getnewbuf() is locked. Note that the returned 2206 * buffer is also considered valid (not marked B_INVAL). 2207 */ 2208 int bsize, maxsize, vmio; 2209 off_t offset; 2210 2211 if (vn_isdisk(vp, NULL)) 2212 bsize = DEV_BSIZE; 2213 else if (vp->v_mountedhere) 2214 bsize = vp->v_mountedhere->mnt_stat.f_iosize; 2215 else if (vp->v_mount) 2216 bsize = vp->v_mount->mnt_stat.f_iosize; 2217 else 2218 bsize = size; 2219 2220 offset = (off_t)blkno * bsize; 2221 vmio = (VOP_GETVOBJECT(vp, NULL) == 0) && (vp->v_flag & VOBJBUF); 2222 maxsize = vmio ? size + (offset & PAGE_MASK) : size; 2223 maxsize = imax(maxsize, bsize); 2224 2225 if ((bp = getnewbuf(slpflag, slptimeo, size, maxsize)) == NULL) { 2226 if (slpflag || slptimeo) { 2227 splx(s); 2228 return NULL; 2229 } 2230 goto loop; 2231 } 2232 2233 /* 2234 * This code is used to make sure that a buffer is not 2235 * created while the getnewbuf routine is blocked. 2236 * This can be a problem whether the vnode is locked or not. 2237 * If the buffer is created out from under us, we have to 2238 * throw away the one we just created. There is now window 2239 * race because we are safely running at splbio() from the 2240 * point of the duplicate buffer creation through to here, 2241 * and we've locked the buffer. 2242 */ 2243 if (gbincore(vp, blkno)) { 2244 bp->b_flags |= B_INVAL; 2245 brelse(bp); 2246 goto loop; 2247 } 2248 2249 /* 2250 * Insert the buffer into the hash, so that it can 2251 * be found by incore. 2252 */ 2253 bp->b_blkno = bp->b_lblkno = blkno; 2254 bp->b_offset = offset; 2255 2256 bgetvp(vp, bp); 2257 LIST_REMOVE(bp, b_hash); 2258 bh = bufhash(vp, blkno); 2259 LIST_INSERT_HEAD(bh, bp, b_hash); 2260 2261 /* 2262 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 2263 * buffer size starts out as 0, B_CACHE will be set by 2264 * allocbuf() for the VMIO case prior to it testing the 2265 * backing store for validity. 2266 */ 2267 2268 if (vmio) { 2269 bp->b_flags |= B_VMIO; 2270 #if defined(VFS_BIO_DEBUG) 2271 if (vp->v_type != VREG) 2272 printf("getblk: vmioing file type %d???\n", vp->v_type); 2273 #endif 2274 } else { 2275 bp->b_flags &= ~B_VMIO; 2276 } 2277 2278 allocbuf(bp, size); 2279 2280 splx(s); 2281 bp->b_flags &= ~B_DONE; 2282 } 2283 return (bp); 2284 } 2285 2286 /* 2287 * Get an empty, disassociated buffer of given size. The buffer is initially 2288 * set to B_INVAL. 2289 */ 2290 struct buf * 2291 geteblk(int size) 2292 { 2293 struct buf *bp; 2294 int s; 2295 int maxsize; 2296 2297 maxsize = (size + BKVAMASK) & ~BKVAMASK; 2298 2299 s = splbio(); 2300 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0); 2301 splx(s); 2302 allocbuf(bp, size); 2303 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 2304 return (bp); 2305 } 2306 2307 2308 /* 2309 * This code constitutes the buffer memory from either anonymous system 2310 * memory (in the case of non-VMIO operations) or from an associated 2311 * VM object (in the case of VMIO operations). This code is able to 2312 * resize a buffer up or down. 2313 * 2314 * Note that this code is tricky, and has many complications to resolve 2315 * deadlock or inconsistant data situations. Tread lightly!!! 2316 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 2317 * the caller. Calling this code willy nilly can result in the loss of data. 2318 * 2319 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 2320 * B_CACHE for the non-VMIO case. 2321 */ 2322 2323 int 2324 allocbuf(struct buf *bp, int size) 2325 { 2326 int newbsize, mbsize; 2327 int i; 2328 2329 if (BUF_REFCNT(bp) == 0) 2330 panic("allocbuf: buffer not busy"); 2331 2332 if (bp->b_kvasize < size) 2333 panic("allocbuf: buffer too small"); 2334 2335 if ((bp->b_flags & B_VMIO) == 0) { 2336 caddr_t origbuf; 2337 int origbufsize; 2338 /* 2339 * Just get anonymous memory from the kernel. Don't 2340 * mess with B_CACHE. 2341 */ 2342 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2343 #if !defined(NO_B_MALLOC) 2344 if (bp->b_flags & B_MALLOC) 2345 newbsize = mbsize; 2346 else 2347 #endif 2348 newbsize = round_page(size); 2349 2350 if (newbsize < bp->b_bufsize) { 2351 #if !defined(NO_B_MALLOC) 2352 /* 2353 * malloced buffers are not shrunk 2354 */ 2355 if (bp->b_flags & B_MALLOC) { 2356 if (newbsize) { 2357 bp->b_bcount = size; 2358 } else { 2359 free(bp->b_data, M_BIOBUF); 2360 bufmallocspace -= bp->b_bufsize; 2361 runningbufspace -= bp->b_bufsize; 2362 if (bp->b_bufsize) 2363 bufspacewakeup(); 2364 bp->b_data = bp->b_kvabase; 2365 bp->b_bufsize = 0; 2366 bp->b_bcount = 0; 2367 bp->b_flags &= ~B_MALLOC; 2368 } 2369 return 1; 2370 } 2371 #endif 2372 vm_hold_free_pages( 2373 bp, 2374 (vm_offset_t) bp->b_data + newbsize, 2375 (vm_offset_t) bp->b_data + bp->b_bufsize); 2376 } else if (newbsize > bp->b_bufsize) { 2377 #if !defined(NO_B_MALLOC) 2378 /* 2379 * We only use malloced memory on the first allocation. 2380 * and revert to page-allocated memory when the buffer 2381 * grows. 2382 */ 2383 if ( (bufmallocspace < maxbufmallocspace) && 2384 (bp->b_bufsize == 0) && 2385 (mbsize <= PAGE_SIZE/2)) { 2386 2387 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 2388 bp->b_bufsize = mbsize; 2389 bp->b_bcount = size; 2390 bp->b_flags |= B_MALLOC; 2391 bufmallocspace += mbsize; 2392 runningbufspace += bp->b_bufsize; 2393 return 1; 2394 } 2395 #endif 2396 origbuf = NULL; 2397 origbufsize = 0; 2398 #if !defined(NO_B_MALLOC) 2399 /* 2400 * If the buffer is growing on its other-than-first allocation, 2401 * then we revert to the page-allocation scheme. 2402 */ 2403 if (bp->b_flags & B_MALLOC) { 2404 origbuf = bp->b_data; 2405 origbufsize = bp->b_bufsize; 2406 bp->b_data = bp->b_kvabase; 2407 bufmallocspace -= bp->b_bufsize; 2408 runningbufspace -= bp->b_bufsize; 2409 if (bp->b_bufsize) 2410 bufspacewakeup(); 2411 bp->b_bufsize = 0; 2412 bp->b_flags &= ~B_MALLOC; 2413 newbsize = round_page(newbsize); 2414 } 2415 #endif 2416 vm_hold_load_pages( 2417 bp, 2418 (vm_offset_t) bp->b_data + bp->b_bufsize, 2419 (vm_offset_t) bp->b_data + newbsize); 2420 #if !defined(NO_B_MALLOC) 2421 if (origbuf) { 2422 bcopy(origbuf, bp->b_data, origbufsize); 2423 free(origbuf, M_BIOBUF); 2424 } 2425 #endif 2426 } 2427 } else { 2428 vm_page_t m; 2429 int desiredpages; 2430 2431 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2432 desiredpages = (size == 0) ? 0 : 2433 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 2434 2435 #if !defined(NO_B_MALLOC) 2436 if (bp->b_flags & B_MALLOC) 2437 panic("allocbuf: VMIO buffer can't be malloced"); 2438 #endif 2439 /* 2440 * Set B_CACHE initially if buffer is 0 length or will become 2441 * 0-length. 2442 */ 2443 if (size == 0 || bp->b_bufsize == 0) 2444 bp->b_flags |= B_CACHE; 2445 2446 if (newbsize < bp->b_bufsize) { 2447 /* 2448 * DEV_BSIZE aligned new buffer size is less then the 2449 * DEV_BSIZE aligned existing buffer size. Figure out 2450 * if we have to remove any pages. 2451 */ 2452 if (desiredpages < bp->b_npages) { 2453 for (i = desiredpages; i < bp->b_npages; i++) { 2454 /* 2455 * the page is not freed here -- it 2456 * is the responsibility of 2457 * vnode_pager_setsize 2458 */ 2459 m = bp->b_pages[i]; 2460 KASSERT(m != bogus_page, 2461 ("allocbuf: bogus page found")); 2462 while (vm_page_sleep_busy(m, TRUE, "biodep")) 2463 ; 2464 2465 bp->b_pages[i] = NULL; 2466 vm_page_unwire(m, 0); 2467 } 2468 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) + 2469 (desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages)); 2470 bp->b_npages = desiredpages; 2471 } 2472 } else if (size > bp->b_bcount) { 2473 /* 2474 * We are growing the buffer, possibly in a 2475 * byte-granular fashion. 2476 */ 2477 struct vnode *vp; 2478 vm_object_t obj; 2479 vm_offset_t toff; 2480 vm_offset_t tinc; 2481 2482 /* 2483 * Step 1, bring in the VM pages from the object, 2484 * allocating them if necessary. We must clear 2485 * B_CACHE if these pages are not valid for the 2486 * range covered by the buffer. 2487 */ 2488 2489 vp = bp->b_vp; 2490 VOP_GETVOBJECT(vp, &obj); 2491 2492 while (bp->b_npages < desiredpages) { 2493 vm_page_t m; 2494 vm_pindex_t pi; 2495 2496 pi = OFF_TO_IDX(bp->b_offset) + bp->b_npages; 2497 if ((m = vm_page_lookup(obj, pi)) == NULL) { 2498 /* 2499 * note: must allocate system pages 2500 * since blocking here could intefere 2501 * with paging I/O, no matter which 2502 * process we are. 2503 */ 2504 m = vm_page_alloc(obj, pi, VM_ALLOC_SYSTEM); 2505 if (m == NULL) { 2506 VM_WAIT; 2507 vm_pageout_deficit += desiredpages - bp->b_npages; 2508 } else { 2509 vm_page_wire(m); 2510 vm_page_wakeup(m); 2511 bp->b_flags &= ~B_CACHE; 2512 bp->b_pages[bp->b_npages] = m; 2513 ++bp->b_npages; 2514 } 2515 continue; 2516 } 2517 2518 /* 2519 * We found a page. If we have to sleep on it, 2520 * retry because it might have gotten freed out 2521 * from under us. 2522 * 2523 * We can only test PG_BUSY here. Blocking on 2524 * m->busy might lead to a deadlock: 2525 * 2526 * vm_fault->getpages->cluster_read->allocbuf 2527 * 2528 */ 2529 2530 if (vm_page_sleep_busy(m, FALSE, "pgtblk")) 2531 continue; 2532 2533 /* 2534 * We have a good page. Should we wakeup the 2535 * page daemon? 2536 */ 2537 if ((curproc != pageproc) && 2538 ((m->queue - m->pc) == PQ_CACHE) && 2539 ((cnt.v_free_count + cnt.v_cache_count) < 2540 (cnt.v_free_min + cnt.v_cache_min))) { 2541 pagedaemon_wakeup(); 2542 } 2543 vm_page_flag_clear(m, PG_ZERO); 2544 vm_page_wire(m); 2545 bp->b_pages[bp->b_npages] = m; 2546 ++bp->b_npages; 2547 } 2548 2549 /* 2550 * Step 2. We've loaded the pages into the buffer, 2551 * we have to figure out if we can still have B_CACHE 2552 * set. Note that B_CACHE is set according to the 2553 * byte-granular range ( bcount and size ), new the 2554 * aligned range ( newbsize ). 2555 * 2556 * The VM test is against m->valid, which is DEV_BSIZE 2557 * aligned. Needless to say, the validity of the data 2558 * needs to also be DEV_BSIZE aligned. Note that this 2559 * fails with NFS if the server or some other client 2560 * extends the file's EOF. If our buffer is resized, 2561 * B_CACHE may remain set! XXX 2562 */ 2563 2564 toff = bp->b_bcount; 2565 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 2566 2567 while ((bp->b_flags & B_CACHE) && toff < size) { 2568 vm_pindex_t pi; 2569 2570 if (tinc > (size - toff)) 2571 tinc = size - toff; 2572 2573 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 2574 PAGE_SHIFT; 2575 2576 vfs_buf_test_cache( 2577 bp, 2578 bp->b_offset, 2579 toff, 2580 tinc, 2581 bp->b_pages[pi] 2582 ); 2583 toff += tinc; 2584 tinc = PAGE_SIZE; 2585 } 2586 2587 /* 2588 * Step 3, fixup the KVM pmap. Remember that 2589 * bp->b_data is relative to bp->b_offset, but 2590 * bp->b_offset may be offset into the first page. 2591 */ 2592 2593 bp->b_data = (caddr_t) 2594 trunc_page((vm_offset_t)bp->b_data); 2595 pmap_qenter( 2596 (vm_offset_t)bp->b_data, 2597 bp->b_pages, 2598 bp->b_npages 2599 ); 2600 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 2601 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 2602 } 2603 } 2604 runningbufspace += (newbsize - bp->b_bufsize); 2605 if (newbsize < bp->b_bufsize) 2606 bufspacewakeup(); 2607 bp->b_bufsize = newbsize; /* actual buffer allocation */ 2608 bp->b_bcount = size; /* requested buffer size */ 2609 return 1; 2610 } 2611 2612 /* 2613 * bufwait: 2614 * 2615 * Wait for buffer I/O completion, returning error status. The buffer 2616 * is left locked and B_DONE on return. B_EINTR is converted into a EINTR 2617 * error and cleared. 2618 */ 2619 int 2620 bufwait(register struct buf * bp) 2621 { 2622 int s; 2623 2624 s = splbio(); 2625 while ((bp->b_flags & B_DONE) == 0) { 2626 if (bp->b_iocmd == BIO_READ) 2627 tsleep(bp, PRIBIO, "biord", 0); 2628 else 2629 tsleep(bp, PRIBIO, "biowr", 0); 2630 } 2631 splx(s); 2632 if (bp->b_flags & B_EINTR) { 2633 bp->b_flags &= ~B_EINTR; 2634 return (EINTR); 2635 } 2636 if (bp->b_ioflags & BIO_ERROR) { 2637 return (bp->b_error ? bp->b_error : EIO); 2638 } else { 2639 return (0); 2640 } 2641 } 2642 2643 /* 2644 * Call back function from struct bio back up to struct buf. 2645 * The corresponding initialization lives in sys/conf.h:DEV_STRATEGY(). 2646 */ 2647 void 2648 bufdonebio(struct bio *bp) 2649 { 2650 bufdone(bp->bio_caller2); 2651 } 2652 2653 /* 2654 * bufdone: 2655 * 2656 * Finish I/O on a buffer, optionally calling a completion function. 2657 * This is usually called from an interrupt so process blocking is 2658 * not allowed. 2659 * 2660 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 2661 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 2662 * assuming B_INVAL is clear. 2663 * 2664 * For the VMIO case, we set B_CACHE if the op was a read and no 2665 * read error occured, or if the op was a write. B_CACHE is never 2666 * set if the buffer is invalid or otherwise uncacheable. 2667 * 2668 * biodone does not mess with B_INVAL, allowing the I/O routine or the 2669 * initiator to leave B_INVAL set to brelse the buffer out of existance 2670 * in the biodone routine. 2671 */ 2672 void 2673 bufdone(struct buf *bp) 2674 { 2675 int s, error; 2676 void (*biodone) __P((struct buf *)); 2677 2678 s = splbio(); 2679 2680 KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp, BUF_REFCNT(bp))); 2681 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 2682 2683 bp->b_flags |= B_DONE; 2684 2685 if (bp->b_iocmd == BIO_DELETE) { 2686 brelse(bp); 2687 splx(s); 2688 return; 2689 } 2690 2691 if (bp->b_iocmd == BIO_WRITE) { 2692 vwakeup(bp); 2693 } 2694 2695 /* call optional completion function if requested */ 2696 if (bp->b_iodone != NULL) { 2697 biodone = bp->b_iodone; 2698 bp->b_iodone = NULL; 2699 (*biodone) (bp); 2700 splx(s); 2701 return; 2702 } 2703 if (LIST_FIRST(&bp->b_dep) != NULL) 2704 buf_complete(bp); 2705 2706 if (bp->b_flags & B_VMIO) { 2707 int i; 2708 vm_ooffset_t foff; 2709 vm_page_t m; 2710 vm_object_t obj; 2711 int iosize; 2712 struct vnode *vp = bp->b_vp; 2713 2714 error = VOP_GETVOBJECT(vp, &obj); 2715 2716 #if defined(VFS_BIO_DEBUG) 2717 if (vp->v_usecount == 0) { 2718 panic("biodone: zero vnode ref count"); 2719 } 2720 2721 if (error) { 2722 panic("biodone: missing VM object"); 2723 } 2724 2725 if ((vp->v_flag & VOBJBUF) == 0) { 2726 panic("biodone: vnode is not setup for merged cache"); 2727 } 2728 #endif 2729 2730 foff = bp->b_offset; 2731 KASSERT(bp->b_offset != NOOFFSET, 2732 ("biodone: no buffer offset")); 2733 2734 if (error) { 2735 panic("biodone: no object"); 2736 } 2737 #if defined(VFS_BIO_DEBUG) 2738 if (obj->paging_in_progress < bp->b_npages) { 2739 printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n", 2740 obj->paging_in_progress, bp->b_npages); 2741 } 2742 #endif 2743 2744 /* 2745 * Set B_CACHE if the op was a normal read and no error 2746 * occured. B_CACHE is set for writes in the b*write() 2747 * routines. 2748 */ 2749 iosize = bp->b_bcount - bp->b_resid; 2750 if (bp->b_iocmd == BIO_READ && 2751 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 2752 !(bp->b_ioflags & BIO_ERROR)) { 2753 bp->b_flags |= B_CACHE; 2754 } 2755 2756 for (i = 0; i < bp->b_npages; i++) { 2757 int bogusflag = 0; 2758 int resid; 2759 2760 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 2761 if (resid > iosize) 2762 resid = iosize; 2763 2764 /* 2765 * cleanup bogus pages, restoring the originals 2766 */ 2767 m = bp->b_pages[i]; 2768 if (m == bogus_page) { 2769 bogusflag = 1; 2770 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 2771 if (!m) { 2772 panic("biodone: page disappeared!"); 2773 #if defined(VFS_BIO_DEBUG) 2774 printf("biodone: page disappeared\n"); 2775 #endif 2776 vm_object_pip_subtract(obj, 1); 2777 bp->b_flags &= ~B_CACHE; 2778 foff = (foff + PAGE_SIZE) & 2779 ~(off_t)PAGE_MASK; 2780 iosize -= resid; 2781 continue; 2782 } 2783 bp->b_pages[i] = m; 2784 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 2785 } 2786 #if defined(VFS_BIO_DEBUG) 2787 if (OFF_TO_IDX(foff) != m->pindex) { 2788 printf( 2789 "biodone: foff(%lu)/m->pindex(%d) mismatch\n", 2790 (unsigned long)foff, m->pindex); 2791 } 2792 #endif 2793 2794 /* 2795 * In the write case, the valid and clean bits are 2796 * already changed correctly ( see bdwrite() ), so we 2797 * only need to do this here in the read case. 2798 */ 2799 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 2800 vfs_page_set_valid(bp, foff, i, m); 2801 } 2802 vm_page_flag_clear(m, PG_ZERO); 2803 2804 /* 2805 * when debugging new filesystems or buffer I/O methods, this 2806 * is the most common error that pops up. if you see this, you 2807 * have not set the page busy flag correctly!!! 2808 */ 2809 if (m->busy == 0) { 2810 printf("biodone: page busy < 0, " 2811 "pindex: %d, foff: 0x(%x,%x), " 2812 "resid: %d, index: %d\n", 2813 (int) m->pindex, (int)(foff >> 32), 2814 (int) foff & 0xffffffff, resid, i); 2815 if (!vn_isdisk(vp, NULL)) 2816 printf(" iosize: %ld, lblkno: %d, flags: 0x%lx, npages: %d\n", 2817 bp->b_vp->v_mount->mnt_stat.f_iosize, 2818 (int) bp->b_lblkno, 2819 bp->b_flags, bp->b_npages); 2820 else 2821 printf(" VDEV, lblkno: %d, flags: 0x%lx, npages: %d\n", 2822 (int) bp->b_lblkno, 2823 bp->b_flags, bp->b_npages); 2824 printf(" valid: 0x%x, dirty: 0x%x, wired: %d\n", 2825 m->valid, m->dirty, m->wire_count); 2826 panic("biodone: page busy < 0\n"); 2827 } 2828 vm_page_io_finish(m); 2829 vm_object_pip_subtract(obj, 1); 2830 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2831 iosize -= resid; 2832 } 2833 if (obj) 2834 vm_object_pip_wakeupn(obj, 0); 2835 } 2836 /* 2837 * For asynchronous completions, release the buffer now. The brelse 2838 * will do a wakeup there if necessary - so no need to do a wakeup 2839 * here in the async case. The sync case always needs to do a wakeup. 2840 */ 2841 2842 if (bp->b_flags & B_ASYNC) { 2843 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 2844 brelse(bp); 2845 else 2846 bqrelse(bp); 2847 } else { 2848 wakeup(bp); 2849 } 2850 splx(s); 2851 } 2852 2853 /* 2854 * This routine is called in lieu of iodone in the case of 2855 * incomplete I/O. This keeps the busy status for pages 2856 * consistant. 2857 */ 2858 void 2859 vfs_unbusy_pages(struct buf * bp) 2860 { 2861 int i; 2862 2863 if (bp->b_flags & B_VMIO) { 2864 struct vnode *vp = bp->b_vp; 2865 vm_object_t obj; 2866 2867 VOP_GETVOBJECT(vp, &obj); 2868 2869 for (i = 0; i < bp->b_npages; i++) { 2870 vm_page_t m = bp->b_pages[i]; 2871 2872 if (m == bogus_page) { 2873 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 2874 if (!m) { 2875 panic("vfs_unbusy_pages: page missing\n"); 2876 } 2877 bp->b_pages[i] = m; 2878 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 2879 } 2880 vm_object_pip_subtract(obj, 1); 2881 vm_page_flag_clear(m, PG_ZERO); 2882 vm_page_io_finish(m); 2883 } 2884 vm_object_pip_wakeupn(obj, 0); 2885 } 2886 } 2887 2888 /* 2889 * vfs_page_set_valid: 2890 * 2891 * Set the valid bits in a page based on the supplied offset. The 2892 * range is restricted to the buffer's size. 2893 * 2894 * This routine is typically called after a read completes. 2895 */ 2896 static void 2897 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m) 2898 { 2899 vm_ooffset_t soff, eoff; 2900 2901 /* 2902 * Start and end offsets in buffer. eoff - soff may not cross a 2903 * page boundry or cross the end of the buffer. The end of the 2904 * buffer, in this case, is our file EOF, not the allocation size 2905 * of the buffer. 2906 */ 2907 soff = off; 2908 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2909 if (eoff > bp->b_offset + bp->b_bcount) 2910 eoff = bp->b_offset + bp->b_bcount; 2911 2912 /* 2913 * Set valid range. This is typically the entire buffer and thus the 2914 * entire page. 2915 */ 2916 if (eoff > soff) { 2917 vm_page_set_validclean( 2918 m, 2919 (vm_offset_t) (soff & PAGE_MASK), 2920 (vm_offset_t) (eoff - soff) 2921 ); 2922 } 2923 } 2924 2925 /* 2926 * This routine is called before a device strategy routine. 2927 * It is used to tell the VM system that paging I/O is in 2928 * progress, and treat the pages associated with the buffer 2929 * almost as being PG_BUSY. Also the object paging_in_progress 2930 * flag is handled to make sure that the object doesn't become 2931 * inconsistant. 2932 * 2933 * Since I/O has not been initiated yet, certain buffer flags 2934 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 2935 * and should be ignored. 2936 */ 2937 void 2938 vfs_busy_pages(struct buf * bp, int clear_modify) 2939 { 2940 int i, bogus; 2941 2942 if (bp->b_flags & B_VMIO) { 2943 struct vnode *vp = bp->b_vp; 2944 vm_object_t obj; 2945 vm_ooffset_t foff; 2946 2947 VOP_GETVOBJECT(vp, &obj); 2948 foff = bp->b_offset; 2949 KASSERT(bp->b_offset != NOOFFSET, 2950 ("vfs_busy_pages: no buffer offset")); 2951 vfs_setdirty(bp); 2952 2953 retry: 2954 for (i = 0; i < bp->b_npages; i++) { 2955 vm_page_t m = bp->b_pages[i]; 2956 if (vm_page_sleep_busy(m, FALSE, "vbpage")) 2957 goto retry; 2958 } 2959 2960 bogus = 0; 2961 for (i = 0; i < bp->b_npages; i++) { 2962 vm_page_t m = bp->b_pages[i]; 2963 2964 vm_page_flag_clear(m, PG_ZERO); 2965 if ((bp->b_flags & B_CLUSTER) == 0) { 2966 vm_object_pip_add(obj, 1); 2967 vm_page_io_start(m); 2968 } 2969 2970 /* 2971 * When readying a buffer for a read ( i.e 2972 * clear_modify == 0 ), it is important to do 2973 * bogus_page replacement for valid pages in 2974 * partially instantiated buffers. Partially 2975 * instantiated buffers can, in turn, occur when 2976 * reconstituting a buffer from its VM backing store 2977 * base. We only have to do this if B_CACHE is 2978 * clear ( which causes the I/O to occur in the 2979 * first place ). The replacement prevents the read 2980 * I/O from overwriting potentially dirty VM-backed 2981 * pages. XXX bogus page replacement is, uh, bogus. 2982 * It may not work properly with small-block devices. 2983 * We need to find a better way. 2984 */ 2985 2986 vm_page_protect(m, VM_PROT_NONE); 2987 if (clear_modify) 2988 vfs_page_set_valid(bp, foff, i, m); 2989 else if (m->valid == VM_PAGE_BITS_ALL && 2990 (bp->b_flags & B_CACHE) == 0) { 2991 bp->b_pages[i] = bogus_page; 2992 bogus++; 2993 } 2994 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2995 } 2996 if (bogus) 2997 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 2998 } 2999 } 3000 3001 /* 3002 * Tell the VM system that the pages associated with this buffer 3003 * are clean. This is used for delayed writes where the data is 3004 * going to go to disk eventually without additional VM intevention. 3005 * 3006 * Note that while we only really need to clean through to b_bcount, we 3007 * just go ahead and clean through to b_bufsize. 3008 */ 3009 static void 3010 vfs_clean_pages(struct buf * bp) 3011 { 3012 int i; 3013 3014 if (bp->b_flags & B_VMIO) { 3015 vm_ooffset_t foff; 3016 3017 foff = bp->b_offset; 3018 KASSERT(bp->b_offset != NOOFFSET, 3019 ("vfs_clean_pages: no buffer offset")); 3020 for (i = 0; i < bp->b_npages; i++) { 3021 vm_page_t m = bp->b_pages[i]; 3022 vm_ooffset_t noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3023 vm_ooffset_t eoff = noff; 3024 3025 if (eoff > bp->b_offset + bp->b_bufsize) 3026 eoff = bp->b_offset + bp->b_bufsize; 3027 vfs_page_set_valid(bp, foff, i, m); 3028 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3029 foff = noff; 3030 } 3031 } 3032 } 3033 3034 /* 3035 * vfs_bio_set_validclean: 3036 * 3037 * Set the range within the buffer to valid and clean. The range is 3038 * relative to the beginning of the buffer, b_offset. Note that b_offset 3039 * itself may be offset from the beginning of the first page. 3040 */ 3041 3042 void 3043 vfs_bio_set_validclean(struct buf *bp, int base, int size) 3044 { 3045 if (bp->b_flags & B_VMIO) { 3046 int i; 3047 int n; 3048 3049 /* 3050 * Fixup base to be relative to beginning of first page. 3051 * Set initial n to be the maximum number of bytes in the 3052 * first page that can be validated. 3053 */ 3054 3055 base += (bp->b_offset & PAGE_MASK); 3056 n = PAGE_SIZE - (base & PAGE_MASK); 3057 3058 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 3059 vm_page_t m = bp->b_pages[i]; 3060 3061 if (n > size) 3062 n = size; 3063 3064 vm_page_set_validclean(m, base & PAGE_MASK, n); 3065 base += n; 3066 size -= n; 3067 n = PAGE_SIZE; 3068 } 3069 } 3070 } 3071 3072 /* 3073 * vfs_bio_clrbuf: 3074 * 3075 * clear a buffer. This routine essentially fakes an I/O, so we need 3076 * to clear BIO_ERROR and B_INVAL. 3077 * 3078 * Note that while we only theoretically need to clear through b_bcount, 3079 * we go ahead and clear through b_bufsize. 3080 */ 3081 3082 void 3083 vfs_bio_clrbuf(struct buf *bp) { 3084 int i, mask = 0; 3085 caddr_t sa, ea; 3086 if ((bp->b_flags & (B_VMIO | B_MALLOC)) == B_VMIO) { 3087 bp->b_flags &= ~B_INVAL; 3088 bp->b_ioflags &= ~BIO_ERROR; 3089 if( (bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 3090 (bp->b_offset & PAGE_MASK) == 0) { 3091 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 3092 if (((bp->b_pages[0]->flags & PG_ZERO) == 0) && 3093 ((bp->b_pages[0]->valid & mask) != mask)) { 3094 bzero(bp->b_data, bp->b_bufsize); 3095 } 3096 bp->b_pages[0]->valid |= mask; 3097 bp->b_resid = 0; 3098 return; 3099 } 3100 ea = sa = bp->b_data; 3101 for(i=0;i<bp->b_npages;i++,sa=ea) { 3102 int j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; 3103 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); 3104 ea = (caddr_t)(vm_offset_t)ulmin( 3105 (u_long)(vm_offset_t)ea, 3106 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); 3107 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 3108 if ((bp->b_pages[i]->valid & mask) == mask) 3109 continue; 3110 if ((bp->b_pages[i]->valid & mask) == 0) { 3111 if ((bp->b_pages[i]->flags & PG_ZERO) == 0) { 3112 bzero(sa, ea - sa); 3113 } 3114 } else { 3115 for (; sa < ea; sa += DEV_BSIZE, j++) { 3116 if (((bp->b_pages[i]->flags & PG_ZERO) == 0) && 3117 (bp->b_pages[i]->valid & (1<<j)) == 0) 3118 bzero(sa, DEV_BSIZE); 3119 } 3120 } 3121 bp->b_pages[i]->valid |= mask; 3122 vm_page_flag_clear(bp->b_pages[i], PG_ZERO); 3123 } 3124 bp->b_resid = 0; 3125 } else { 3126 clrbuf(bp); 3127 } 3128 } 3129 3130 /* 3131 * vm_hold_load_pages and vm_hold_unload pages get pages into 3132 * a buffers address space. The pages are anonymous and are 3133 * not associated with a file object. 3134 */ 3135 void 3136 vm_hold_load_pages(struct buf * bp, vm_offset_t from, vm_offset_t to) 3137 { 3138 vm_offset_t pg; 3139 vm_page_t p; 3140 int index; 3141 3142 to = round_page(to); 3143 from = round_page(from); 3144 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3145 3146 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3147 3148 tryagain: 3149 3150 /* 3151 * note: must allocate system pages since blocking here 3152 * could intefere with paging I/O, no matter which 3153 * process we are. 3154 */ 3155 p = vm_page_alloc(kernel_object, 3156 ((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 3157 VM_ALLOC_SYSTEM); 3158 if (!p) { 3159 vm_pageout_deficit += (to - from) >> PAGE_SHIFT; 3160 VM_WAIT; 3161 goto tryagain; 3162 } 3163 vm_page_wire(p); 3164 p->valid = VM_PAGE_BITS_ALL; 3165 vm_page_flag_clear(p, PG_ZERO); 3166 pmap_kenter(pg, VM_PAGE_TO_PHYS(p)); 3167 bp->b_pages[index] = p; 3168 vm_page_wakeup(p); 3169 } 3170 bp->b_npages = index; 3171 } 3172 3173 void 3174 vm_hold_free_pages(struct buf * bp, vm_offset_t from, vm_offset_t to) 3175 { 3176 vm_offset_t pg; 3177 vm_page_t p; 3178 int index, newnpages; 3179 3180 from = round_page(from); 3181 to = round_page(to); 3182 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3183 3184 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3185 p = bp->b_pages[index]; 3186 if (p && (index < bp->b_npages)) { 3187 if (p->busy) { 3188 printf("vm_hold_free_pages: blkno: %d, lblkno: %d\n", 3189 bp->b_blkno, bp->b_lblkno); 3190 } 3191 bp->b_pages[index] = NULL; 3192 pmap_kremove(pg); 3193 vm_page_busy(p); 3194 vm_page_unwire(p, 0); 3195 vm_page_free(p); 3196 } 3197 } 3198 bp->b_npages = newnpages; 3199 } 3200 3201 3202 #include "opt_ddb.h" 3203 #ifdef DDB 3204 #include <ddb/ddb.h> 3205 3206 DB_SHOW_COMMAND(buffer, db_show_buffer) 3207 { 3208 /* get args */ 3209 struct buf *bp = (struct buf *)addr; 3210 3211 if (!have_addr) { 3212 db_printf("usage: show buffer <addr>\n"); 3213 return; 3214 } 3215 3216 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS); 3217 db_printf("b_error = %d, b_bufsize = %ld, b_bcount = %ld, " 3218 "b_resid = %ld\nb_dev = (%d,%d), b_data = %p, " 3219 "b_blkno = %d, b_pblkno = %d\n", 3220 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 3221 major(bp->b_dev), minor(bp->b_dev), 3222 bp->b_data, bp->b_blkno, bp->b_pblkno); 3223 if (bp->b_npages) { 3224 int i; 3225 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 3226 for (i = 0; i < bp->b_npages; i++) { 3227 vm_page_t m; 3228 m = bp->b_pages[i]; 3229 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 3230 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 3231 if ((i + 1) < bp->b_npages) 3232 db_printf(","); 3233 } 3234 db_printf("\n"); 3235 } 3236 } 3237 #endif /* DDB */ 3238