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 #define VMIO 31 #include <sys/param.h> 32 #include <sys/systm.h> 33 #include <sys/kernel.h> 34 #include <sys/sysctl.h> 35 #include <sys/proc.h> 36 #include <sys/kthread.h> 37 #include <sys/vnode.h> 38 #include <sys/vmmeter.h> 39 #include <sys/lock.h> 40 #include <vm/vm.h> 41 #include <vm/vm_param.h> 42 #include <vm/vm_prot.h> 43 #include <vm/vm_kern.h> 44 #include <vm/vm_pageout.h> 45 #include <vm/vm_page.h> 46 #include <vm/vm_object.h> 47 #include <vm/vm_extern.h> 48 #include <vm/vm_map.h> 49 #include <sys/buf.h> 50 #include <sys/mount.h> 51 #include <sys/malloc.h> 52 #include <sys/resourcevar.h> 53 #include <sys/conf.h> 54 55 static MALLOC_DEFINE(M_BIOBUF, "BIO buffer", "BIO buffer"); 56 57 struct bio_ops bioops; /* I/O operation notification */ 58 59 struct buf *buf; /* buffer header pool */ 60 struct swqueue bswlist; 61 62 static void vm_hold_free_pages(struct buf * bp, vm_offset_t from, 63 vm_offset_t to); 64 static void vm_hold_load_pages(struct buf * bp, vm_offset_t from, 65 vm_offset_t to); 66 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, 67 int pageno, vm_page_t m); 68 static void vfs_clean_pages(struct buf * bp); 69 static void vfs_setdirty(struct buf *bp); 70 static void vfs_vmio_release(struct buf *bp); 71 static int flushbufqueues(void); 72 73 static int bd_request; 74 75 static void buf_daemon __P((void)); 76 /* 77 * bogus page -- for I/O to/from partially complete buffers 78 * this is a temporary solution to the problem, but it is not 79 * really that bad. it would be better to split the buffer 80 * for input in the case of buffers partially already in memory, 81 * but the code is intricate enough already. 82 */ 83 vm_page_t bogus_page; 84 int runningbufspace; 85 int vmiodirenable = FALSE; 86 static vm_offset_t bogus_offset; 87 88 static int bufspace, maxbufspace, vmiospace, 89 bufmallocspace, maxbufmallocspace, hibufspace; 90 #if 0 91 static int maxvmiobufspace; 92 #endif 93 static int maxbdrun; 94 static int needsbuffer; 95 static int numdirtybuffers, lodirtybuffers, hidirtybuffers; 96 static int numfreebuffers, lofreebuffers, hifreebuffers; 97 static int getnewbufcalls; 98 static int getnewbufrestarts; 99 static int kvafreespace; 100 101 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, 102 &numdirtybuffers, 0, ""); 103 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, 104 &lodirtybuffers, 0, ""); 105 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, 106 &hidirtybuffers, 0, ""); 107 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, 108 &numfreebuffers, 0, ""); 109 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, 110 &lofreebuffers, 0, ""); 111 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, 112 &hifreebuffers, 0, ""); 113 SYSCTL_INT(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, 114 &runningbufspace, 0, ""); 115 SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RW, 116 &maxbufspace, 0, ""); 117 SYSCTL_INT(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, 118 &hibufspace, 0, ""); 119 SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, 120 &bufspace, 0, ""); 121 SYSCTL_INT(_vfs, OID_AUTO, maxbdrun, CTLFLAG_RW, 122 &maxbdrun, 0, ""); 123 #if 0 124 SYSCTL_INT(_vfs, OID_AUTO, maxvmiobufspace, CTLFLAG_RW, 125 &maxvmiobufspace, 0, ""); 126 #endif 127 SYSCTL_INT(_vfs, OID_AUTO, vmiospace, CTLFLAG_RD, 128 &vmiospace, 0, ""); 129 SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, 130 &maxbufmallocspace, 0, ""); 131 SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, 132 &bufmallocspace, 0, ""); 133 SYSCTL_INT(_vfs, OID_AUTO, kvafreespace, CTLFLAG_RD, 134 &kvafreespace, 0, ""); 135 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, 136 &getnewbufcalls, 0, ""); 137 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, 138 &getnewbufrestarts, 0, ""); 139 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, 140 &vmiodirenable, 0, ""); 141 142 143 static int bufhashmask; 144 static LIST_HEAD(bufhashhdr, buf) *bufhashtbl, invalhash; 145 struct bqueues bufqueues[BUFFER_QUEUES] = { { 0 } }; 146 char *buf_wmesg = BUF_WMESG; 147 148 extern int vm_swap_size; 149 150 #define BUF_MAXUSE 24 151 152 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 153 #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */ 154 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ 155 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 156 #define VFS_BIO_NEED_KVASPACE 0x10 /* wait for buffer_map space, emerg */ 157 158 /* 159 * Buffer hash table code. Note that the logical block scans linearly, which 160 * gives us some L1 cache locality. 161 */ 162 163 static __inline 164 struct bufhashhdr * 165 bufhash(struct vnode *vnp, daddr_t bn) 166 { 167 return(&bufhashtbl[(((uintptr_t)(vnp) >> 7) + (int)bn) & bufhashmask]); 168 } 169 170 /* 171 * kvaspacewakeup: 172 * 173 * Called when kva space is potential available for recovery or when 174 * kva space is recovered in the buffer_map. This function wakes up 175 * anyone waiting for buffer_map kva space. Even though the buffer_map 176 * is larger then maxbufspace, this situation will typically occur 177 * when the buffer_map gets fragmented. 178 */ 179 180 static __inline void 181 kvaspacewakeup(void) 182 { 183 /* 184 * If someone is waiting for KVA space, wake them up. Even 185 * though we haven't freed the kva space yet, the waiting 186 * process will be able to now. 187 */ 188 if (needsbuffer & VFS_BIO_NEED_KVASPACE) { 189 needsbuffer &= ~VFS_BIO_NEED_KVASPACE; 190 wakeup(&needsbuffer); 191 } 192 } 193 194 /* 195 * numdirtywakeup: 196 * 197 * If someone is blocked due to there being too many dirty buffers, 198 * and numdirtybuffers is now reasonable, wake them up. 199 */ 200 201 static __inline void 202 numdirtywakeup(void) 203 { 204 if (numdirtybuffers < hidirtybuffers) { 205 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) { 206 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH; 207 wakeup(&needsbuffer); 208 } 209 } 210 } 211 212 /* 213 * bufspacewakeup: 214 * 215 * Called when buffer space is potentially available for recovery or when 216 * buffer space is recovered. getnewbuf() will block on this flag when 217 * it is unable to free sufficient buffer space. Buffer space becomes 218 * recoverable when bp's get placed back in the queues. 219 */ 220 221 static __inline void 222 bufspacewakeup(void) 223 { 224 /* 225 * If someone is waiting for BUF space, wake them up. Even 226 * though we haven't freed the kva space yet, the waiting 227 * process will be able to now. 228 */ 229 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) { 230 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE; 231 wakeup(&needsbuffer); 232 } 233 } 234 235 /* 236 * bufcountwakeup: 237 * 238 * Called when a buffer has been added to one of the free queues to 239 * account for the buffer and to wakeup anyone waiting for free buffers. 240 * This typically occurs when large amounts of metadata are being handled 241 * by the buffer cache ( else buffer space runs out first, usually ). 242 */ 243 244 static __inline void 245 bufcountwakeup(void) 246 { 247 ++numfreebuffers; 248 if (needsbuffer) { 249 needsbuffer &= ~VFS_BIO_NEED_ANY; 250 if (numfreebuffers >= hifreebuffers) 251 needsbuffer &= ~VFS_BIO_NEED_FREE; 252 wakeup(&needsbuffer); 253 } 254 } 255 256 /* 257 * vfs_buf_test_cache: 258 * 259 * Called when a buffer is extended. This function clears the B_CACHE 260 * bit if the newly extended portion of the buffer does not contain 261 * valid data. 262 */ 263 static __inline__ 264 void 265 vfs_buf_test_cache(struct buf *bp, 266 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 267 vm_page_t m) 268 { 269 if (bp->b_flags & B_CACHE) { 270 int base = (foff + off) & PAGE_MASK; 271 if (vm_page_is_valid(m, base, size) == 0) 272 bp->b_flags &= ~B_CACHE; 273 } 274 } 275 276 static __inline__ 277 void 278 bd_wakeup(int dirtybuflevel) 279 { 280 if (numdirtybuffers >= dirtybuflevel && bd_request == 0) { 281 bd_request = 1; 282 wakeup(&bd_request); 283 } 284 } 285 286 287 /* 288 * Initialize buffer headers and related structures. 289 */ 290 291 caddr_t 292 bufhashinit(caddr_t vaddr) 293 { 294 /* first, make a null hash table */ 295 for (bufhashmask = 8; bufhashmask < nbuf / 4; bufhashmask <<= 1) 296 ; 297 bufhashtbl = (void *)vaddr; 298 vaddr = vaddr + sizeof(*bufhashtbl) * bufhashmask; 299 --bufhashmask; 300 return(vaddr); 301 } 302 303 void 304 bufinit(void) 305 { 306 struct buf *bp; 307 int i; 308 309 TAILQ_INIT(&bswlist); 310 LIST_INIT(&invalhash); 311 simple_lock_init(&buftimelock); 312 313 for (i = 0; i <= bufhashmask; i++) 314 LIST_INIT(&bufhashtbl[i]); 315 316 /* next, make a null set of free lists */ 317 for (i = 0; i < BUFFER_QUEUES; i++) 318 TAILQ_INIT(&bufqueues[i]); 319 320 /* finally, initialize each buffer header and stick on empty q */ 321 for (i = 0; i < nbuf; i++) { 322 bp = &buf[i]; 323 bzero(bp, sizeof *bp); 324 bp->b_flags = B_INVAL; /* we're just an empty header */ 325 bp->b_dev = NODEV; 326 bp->b_rcred = NOCRED; 327 bp->b_wcred = NOCRED; 328 bp->b_qindex = QUEUE_EMPTY; 329 bp->b_xflags = 0; 330 LIST_INIT(&bp->b_dep); 331 BUF_LOCKINIT(bp); 332 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 333 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 334 } 335 336 /* 337 * maxbufspace is currently calculated to support all filesystem 338 * blocks to be 8K. If you happen to use a 16K filesystem, the size 339 * of the buffer cache is still the same as it would be for 8K 340 * filesystems. This keeps the size of the buffer cache "in check" 341 * for big block filesystems. 342 * 343 * maxbufspace is calculated as around 50% of the KVA available in 344 * the buffer_map ( DFLTSIZE vs BKVASIZE ), I presume to reduce the 345 * effect of fragmentation. 346 */ 347 maxbufspace = (nbuf + 8) * DFLTBSIZE; 348 if ((hibufspace = maxbufspace - MAXBSIZE * 5) <= MAXBSIZE) 349 hibufspace = 3 * maxbufspace / 4; 350 #if 0 351 /* 352 * reserve 1/3 of the buffers for metadata (VDIR) which might not be VMIO'ed 353 */ 354 maxvmiobufspace = 2 * hibufspace / 3; 355 #endif 356 /* 357 * Limit the amount of malloc memory since it is wired permanently into 358 * the kernel space. Even though this is accounted for in the buffer 359 * allocation, we don't want the malloced region to grow uncontrolled. 360 * The malloc scheme improves memory utilization significantly on average 361 * (small) directories. 362 */ 363 maxbufmallocspace = hibufspace / 20; 364 365 /* 366 * Reduce the chance of a deadlock occuring by limiting the number 367 * of delayed-write dirty buffers we allow to stack up. 368 */ 369 lodirtybuffers = nbuf / 7 + 10; 370 hidirtybuffers = nbuf / 4 + 20; 371 numdirtybuffers = 0; 372 373 /* 374 * Try to keep the number of free buffers in the specified range, 375 * and give the syncer access to an emergency reserve. 376 */ 377 lofreebuffers = nbuf / 18 + 5; 378 hifreebuffers = 2 * lofreebuffers; 379 numfreebuffers = nbuf; 380 381 /* 382 * Maximum number of async ops initiated per buf_daemon loop. This is 383 * somewhat of a hack at the moment, we really need to limit ourselves 384 * based on the number of bytes of I/O in-transit that were initiated 385 * from buf_daemon. 386 */ 387 if ((maxbdrun = nswbuf / 4) < 4) 388 maxbdrun = 4; 389 390 kvafreespace = 0; 391 392 bogus_offset = kmem_alloc_pageable(kernel_map, PAGE_SIZE); 393 bogus_page = vm_page_alloc(kernel_object, 394 ((bogus_offset - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 395 VM_ALLOC_NORMAL); 396 cnt.v_wire_count++; 397 398 } 399 400 /* 401 * Free the kva allocation for a buffer 402 * Must be called only at splbio or higher, 403 * as this is the only locking for buffer_map. 404 */ 405 static void 406 bfreekva(struct buf * bp) 407 { 408 if (bp->b_kvasize) { 409 vm_map_delete(buffer_map, 410 (vm_offset_t) bp->b_kvabase, 411 (vm_offset_t) bp->b_kvabase + bp->b_kvasize 412 ); 413 bp->b_kvasize = 0; 414 kvaspacewakeup(); 415 } 416 } 417 418 /* 419 * bremfree: 420 * 421 * Remove the buffer from the appropriate free list. 422 */ 423 void 424 bremfree(struct buf * bp) 425 { 426 int s = splbio(); 427 int old_qindex = bp->b_qindex; 428 429 if (bp->b_qindex != QUEUE_NONE) { 430 if (bp->b_qindex == QUEUE_EMPTYKVA) { 431 kvafreespace -= bp->b_kvasize; 432 } 433 KASSERT(BUF_REFCNT(bp) == 1, ("bremfree: bp %p not locked",bp)); 434 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 435 bp->b_qindex = QUEUE_NONE; 436 runningbufspace += bp->b_bufsize; 437 } else { 438 #if !defined(MAX_PERF) 439 if (BUF_REFCNT(bp) <= 1) 440 panic("bremfree: removing a buffer not on a queue"); 441 #endif 442 } 443 444 /* 445 * Fixup numfreebuffers count. If the buffer is invalid or not 446 * delayed-write, and it was on the EMPTY, LRU, or AGE queues, 447 * the buffer was free and we must decrement numfreebuffers. 448 */ 449 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { 450 switch(old_qindex) { 451 case QUEUE_DIRTY: 452 case QUEUE_CLEAN: 453 case QUEUE_EMPTY: 454 case QUEUE_EMPTYKVA: 455 --numfreebuffers; 456 break; 457 default: 458 break; 459 } 460 } 461 splx(s); 462 } 463 464 465 /* 466 * Get a buffer with the specified data. Look in the cache first. We 467 * must clear B_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 468 * is set, the buffer is valid and we do not have to do anything ( see 469 * getblk() ). 470 */ 471 int 472 bread(struct vnode * vp, daddr_t blkno, int size, struct ucred * cred, 473 struct buf ** bpp) 474 { 475 struct buf *bp; 476 477 bp = getblk(vp, blkno, size, 0, 0); 478 *bpp = bp; 479 480 /* if not found in cache, do some I/O */ 481 if ((bp->b_flags & B_CACHE) == 0) { 482 if (curproc != NULL) 483 curproc->p_stats->p_ru.ru_inblock++; 484 KASSERT(!(bp->b_flags & B_ASYNC), ("bread: illegal async bp %p", bp)); 485 bp->b_flags |= B_READ; 486 bp->b_flags &= ~(B_ERROR | B_INVAL); 487 if (bp->b_rcred == NOCRED) { 488 if (cred != NOCRED) 489 crhold(cred); 490 bp->b_rcred = cred; 491 } 492 vfs_busy_pages(bp, 0); 493 VOP_STRATEGY(vp, bp); 494 return (biowait(bp)); 495 } 496 return (0); 497 } 498 499 /* 500 * Operates like bread, but also starts asynchronous I/O on 501 * read-ahead blocks. We must clear B_ERROR and B_INVAL prior 502 * to initiating I/O . If B_CACHE is set, the buffer is valid 503 * and we do not have to do anything. 504 */ 505 int 506 breadn(struct vnode * vp, daddr_t blkno, int size, 507 daddr_t * rablkno, int *rabsize, 508 int cnt, struct ucred * cred, struct buf ** bpp) 509 { 510 struct buf *bp, *rabp; 511 int i; 512 int rv = 0, readwait = 0; 513 514 *bpp = bp = getblk(vp, blkno, size, 0, 0); 515 516 /* if not found in cache, do some I/O */ 517 if ((bp->b_flags & B_CACHE) == 0) { 518 if (curproc != NULL) 519 curproc->p_stats->p_ru.ru_inblock++; 520 bp->b_flags |= B_READ; 521 bp->b_flags &= ~(B_ERROR | B_INVAL); 522 if (bp->b_rcred == NOCRED) { 523 if (cred != NOCRED) 524 crhold(cred); 525 bp->b_rcred = cred; 526 } 527 vfs_busy_pages(bp, 0); 528 VOP_STRATEGY(vp, bp); 529 ++readwait; 530 } 531 532 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 533 if (inmem(vp, *rablkno)) 534 continue; 535 rabp = getblk(vp, *rablkno, *rabsize, 0, 0); 536 537 if ((rabp->b_flags & B_CACHE) == 0) { 538 if (curproc != NULL) 539 curproc->p_stats->p_ru.ru_inblock++; 540 rabp->b_flags |= B_READ | B_ASYNC; 541 rabp->b_flags &= ~(B_ERROR | B_INVAL); 542 if (rabp->b_rcred == NOCRED) { 543 if (cred != NOCRED) 544 crhold(cred); 545 rabp->b_rcred = cred; 546 } 547 vfs_busy_pages(rabp, 0); 548 BUF_KERNPROC(rabp); 549 VOP_STRATEGY(vp, rabp); 550 } else { 551 brelse(rabp); 552 } 553 } 554 555 if (readwait) { 556 rv = biowait(bp); 557 } 558 return (rv); 559 } 560 561 /* 562 * Write, release buffer on completion. (Done by iodone 563 * if async). Do not bother writing anything if the buffer 564 * is invalid. 565 * 566 * Note that we set B_CACHE here, indicating that buffer is 567 * fully valid and thus cacheable. This is true even of NFS 568 * now so we set it generally. This could be set either here 569 * or in biodone() since the I/O is synchronous. We put it 570 * here. 571 */ 572 int 573 bwrite(struct buf * bp) 574 { 575 int oldflags, s; 576 struct vnode *vp; 577 struct mount *mp; 578 579 if (bp->b_flags & B_INVAL) { 580 brelse(bp); 581 return (0); 582 } 583 584 oldflags = bp->b_flags; 585 586 #if !defined(MAX_PERF) 587 if (BUF_REFCNT(bp) == 0) 588 panic("bwrite: buffer is not busy???"); 589 #endif 590 s = splbio(); 591 bundirty(bp); 592 593 bp->b_flags &= ~(B_READ | B_DONE | B_ERROR); 594 bp->b_flags |= B_WRITEINPROG | B_CACHE; 595 596 bp->b_vp->v_numoutput++; 597 vfs_busy_pages(bp, 1); 598 if (curproc != NULL) 599 curproc->p_stats->p_ru.ru_oublock++; 600 splx(s); 601 if (oldflags & B_ASYNC) 602 BUF_KERNPROC(bp); 603 VOP_STRATEGY(bp->b_vp, bp); 604 605 /* 606 * Collect statistics on synchronous and asynchronous writes. 607 * Writes to block devices are charged to their associated 608 * filesystem (if any). 609 */ 610 if ((vp = bp->b_vp) != NULL) { 611 if (vp->v_type == VBLK) 612 mp = vp->v_specmountpoint; 613 else 614 mp = vp->v_mount; 615 if (mp != NULL) { 616 if ((oldflags & B_ASYNC) == 0) 617 mp->mnt_stat.f_syncwrites++; 618 else 619 mp->mnt_stat.f_asyncwrites++; 620 } 621 } 622 623 if ((oldflags & B_ASYNC) == 0) { 624 int rtval = biowait(bp); 625 brelse(bp); 626 return (rtval); 627 } 628 629 return (0); 630 } 631 632 /* 633 * Delayed write. (Buffer is marked dirty). Do not bother writing 634 * anything if the buffer is marked invalid. 635 * 636 * Note that since the buffer must be completely valid, we can safely 637 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 638 * biodone() in order to prevent getblk from writing the buffer 639 * out synchronously. 640 */ 641 void 642 bdwrite(struct buf * bp) 643 { 644 #if 0 645 struct vnode *vp; 646 #endif 647 648 #if !defined(MAX_PERF) 649 if (BUF_REFCNT(bp) == 0) 650 panic("bdwrite: buffer is not busy"); 651 #endif 652 653 if (bp->b_flags & B_INVAL) { 654 brelse(bp); 655 return; 656 } 657 bdirty(bp); 658 659 /* 660 * Set B_CACHE, indicating that the buffer is fully valid. This is 661 * true even of NFS now. 662 */ 663 bp->b_flags |= B_CACHE; 664 665 /* 666 * This bmap keeps the system from needing to do the bmap later, 667 * perhaps when the system is attempting to do a sync. Since it 668 * is likely that the indirect block -- or whatever other datastructure 669 * that the filesystem needs is still in memory now, it is a good 670 * thing to do this. Note also, that if the pageout daemon is 671 * requesting a sync -- there might not be enough memory to do 672 * the bmap then... So, this is important to do. 673 */ 674 if (bp->b_lblkno == bp->b_blkno) { 675 VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 676 } 677 678 /* 679 * Set the *dirty* buffer range based upon the VM system dirty pages. 680 */ 681 vfs_setdirty(bp); 682 683 /* 684 * We need to do this here to satisfy the vnode_pager and the 685 * pageout daemon, so that it thinks that the pages have been 686 * "cleaned". Note that since the pages are in a delayed write 687 * buffer -- the VFS layer "will" see that the pages get written 688 * out on the next sync, or perhaps the cluster will be completed. 689 */ 690 vfs_clean_pages(bp); 691 bqrelse(bp); 692 693 /* 694 * Wakeup the buffer flushing daemon if we have saturated the 695 * buffer cache. 696 */ 697 698 bd_wakeup(hidirtybuffers); 699 700 /* 701 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 702 * due to the softdep code. 703 */ 704 #if 0 705 /* 706 * XXX The soft dependency code is not prepared to 707 * have I/O done when a bdwrite is requested. For 708 * now we just let the write be delayed if it is 709 * requested by the soft dependency code. 710 */ 711 if ((vp = bp->b_vp) && 712 ((vp->v_type == VBLK && vp->v_specmountpoint && 713 (vp->v_specmountpoint->mnt_flag & MNT_SOFTDEP)) || 714 (vp->v_mount && (vp->v_mount->mnt_flag & MNT_SOFTDEP)))) 715 return; 716 #endif 717 } 718 719 /* 720 * bdirty: 721 * 722 * Turn buffer into delayed write request. We must clear B_READ and 723 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 724 * itself to properly update it in the dirty/clean lists. We mark it 725 * B_DONE to ensure that any asynchronization of the buffer properly 726 * clears B_DONE ( else a panic will occur later ). 727 * 728 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 729 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 730 * should only be called if the buffer is known-good. 731 * 732 * Since the buffer is not on a queue, we do not update the numfreebuffers 733 * count. 734 * 735 * Must be called at splbio(). 736 * The buffer must be on QUEUE_NONE. 737 */ 738 void 739 bdirty(bp) 740 struct buf *bp; 741 { 742 KASSERT(bp->b_qindex == QUEUE_NONE, ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 743 bp->b_flags &= ~(B_READ|B_RELBUF); 744 745 if ((bp->b_flags & B_DELWRI) == 0) { 746 bp->b_flags |= B_DONE | B_DELWRI; 747 reassignbuf(bp, bp->b_vp); 748 ++numdirtybuffers; 749 bd_wakeup(hidirtybuffers); 750 } 751 } 752 753 /* 754 * bundirty: 755 * 756 * Clear B_DELWRI for buffer. 757 * 758 * Since the buffer is not on a queue, we do not update the numfreebuffers 759 * count. 760 * 761 * Must be called at splbio(). 762 * The buffer must be on QUEUE_NONE. 763 */ 764 765 void 766 bundirty(bp) 767 struct buf *bp; 768 { 769 KASSERT(bp->b_qindex == QUEUE_NONE, ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 770 771 if (bp->b_flags & B_DELWRI) { 772 bp->b_flags &= ~B_DELWRI; 773 reassignbuf(bp, bp->b_vp); 774 --numdirtybuffers; 775 numdirtywakeup(); 776 } 777 } 778 779 /* 780 * bawrite: 781 * 782 * Asynchronous write. Start output on a buffer, but do not wait for 783 * it to complete. The buffer is released when the output completes. 784 * 785 * bwrite() ( or the VOP routine anyway ) is responsible for handling 786 * B_INVAL buffers. Not us. 787 */ 788 void 789 bawrite(struct buf * bp) 790 { 791 bp->b_flags |= B_ASYNC; 792 (void) VOP_BWRITE(bp->b_vp, bp); 793 } 794 795 /* 796 * bowrite: 797 * 798 * Ordered write. Start output on a buffer, and flag it so that the 799 * device will write it in the order it was queued. The buffer is 800 * released when the output completes. bwrite() ( or the VOP routine 801 * anyway ) is responsible for handling B_INVAL buffers. 802 */ 803 int 804 bowrite(struct buf * bp) 805 { 806 bp->b_flags |= B_ORDERED | B_ASYNC; 807 return (VOP_BWRITE(bp->b_vp, bp)); 808 } 809 810 /* 811 * bwillwrite: 812 * 813 * Called prior to the locking of any vnodes when we are expecting to 814 * write. We do not want to starve the buffer cache with too many 815 * dirty buffers so we block here. By blocking prior to the locking 816 * of any vnodes we attempt to avoid the situation where a locked vnode 817 * prevents the various system daemons from flushing related buffers. 818 */ 819 820 void 821 bwillwrite(void) 822 { 823 int twenty = (hidirtybuffers - lodirtybuffers) / 5; 824 825 if (numdirtybuffers > hidirtybuffers + twenty) { 826 int s; 827 828 s = splbio(); 829 while (numdirtybuffers > hidirtybuffers) { 830 bd_wakeup(hidirtybuffers); 831 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH; 832 tsleep(&needsbuffer, (PRIBIO + 4), "flswai", 0); 833 } 834 splx(s); 835 } 836 } 837 838 /* 839 * brelse: 840 * 841 * Release a busy buffer and, if requested, free its resources. The 842 * buffer will be stashed in the appropriate bufqueue[] allowing it 843 * to be accessed later as a cache entity or reused for other purposes. 844 */ 845 void 846 brelse(struct buf * bp) 847 { 848 int s; 849 850 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 851 852 #if 0 853 if (bp->b_flags & B_CLUSTER) { 854 relpbuf(bp, NULL); 855 return; 856 } 857 #endif 858 859 s = splbio(); 860 861 if (bp->b_flags & B_LOCKED) 862 bp->b_flags &= ~B_ERROR; 863 864 if ((bp->b_flags & (B_READ | B_ERROR | B_INVAL)) == B_ERROR) { 865 /* 866 * Failed write, redirty. Must clear B_ERROR to prevent 867 * pages from being scrapped. If B_INVAL is set then 868 * this case is not run and the next case is run to 869 * destroy the buffer. B_INVAL can occur if the buffer 870 * is outside the range supported by the underlying device. 871 */ 872 bp->b_flags &= ~B_ERROR; 873 bdirty(bp); 874 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR | B_FREEBUF)) || 875 (bp->b_bufsize <= 0)) { 876 /* 877 * Either a failed I/O or we were asked to free or not 878 * cache the buffer. 879 */ 880 bp->b_flags |= B_INVAL; 881 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_deallocate) 882 (*bioops.io_deallocate)(bp); 883 if (bp->b_flags & B_DELWRI) { 884 --numdirtybuffers; 885 numdirtywakeup(); 886 } 887 bp->b_flags &= ~(B_DELWRI | B_CACHE | B_FREEBUF); 888 if ((bp->b_flags & B_VMIO) == 0) { 889 if (bp->b_bufsize) 890 allocbuf(bp, 0); 891 if (bp->b_vp) 892 brelvp(bp); 893 } 894 } 895 896 /* 897 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 898 * is called with B_DELWRI set, the underlying pages may wind up 899 * getting freed causing a previous write (bdwrite()) to get 'lost' 900 * because pages associated with a B_DELWRI bp are marked clean. 901 * 902 * We still allow the B_INVAL case to call vfs_vmio_release(), even 903 * if B_DELWRI is set. 904 */ 905 906 if (bp->b_flags & B_DELWRI) 907 bp->b_flags &= ~B_RELBUF; 908 909 /* 910 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 911 * constituted, not even NFS buffers now. Two flags effect this. If 912 * B_INVAL, the struct buf is invalidated but the VM object is kept 913 * around ( i.e. so it is trivial to reconstitute the buffer later ). 914 * 915 * If B_ERROR or B_NOCACHE is set, pages in the VM object will be 916 * invalidated. B_ERROR cannot be set for a failed write unless the 917 * buffer is also B_INVAL because it hits the re-dirtying code above. 918 * 919 * Normally we can do this whether a buffer is B_DELWRI or not. If 920 * the buffer is an NFS buffer, it is tracking piecemeal writes or 921 * the commit state and we cannot afford to lose the buffer. 922 */ 923 if ((bp->b_flags & B_VMIO) 924 && !(bp->b_vp->v_tag == VT_NFS && 925 bp->b_vp->v_type != VBLK && 926 (bp->b_flags & B_DELWRI)) 927 ) { 928 929 int i, j, resid; 930 vm_page_t m; 931 off_t foff; 932 vm_pindex_t poff; 933 vm_object_t obj; 934 struct vnode *vp; 935 936 vp = bp->b_vp; 937 938 /* 939 * Get the base offset and length of the buffer. Note that 940 * for block sizes that are less then PAGE_SIZE, the b_data 941 * base of the buffer does not represent exactly b_offset and 942 * neither b_offset nor b_size are necessarily page aligned. 943 * Instead, the starting position of b_offset is: 944 * 945 * b_data + (b_offset & PAGE_MASK) 946 * 947 * block sizes less then DEV_BSIZE (usually 512) are not 948 * supported due to the page granularity bits (m->valid, 949 * m->dirty, etc...). 950 * 951 * See man buf(9) for more information 952 */ 953 954 resid = bp->b_bufsize; 955 foff = bp->b_offset; 956 957 for (i = 0; i < bp->b_npages; i++) { 958 m = bp->b_pages[i]; 959 vm_page_flag_clear(m, PG_ZERO); 960 if (m == bogus_page) { 961 962 obj = (vm_object_t) vp->v_object; 963 poff = OFF_TO_IDX(bp->b_offset); 964 965 for (j = i; j < bp->b_npages; j++) { 966 m = bp->b_pages[j]; 967 if (m == bogus_page) { 968 m = vm_page_lookup(obj, poff + j); 969 #if !defined(MAX_PERF) 970 if (!m) { 971 panic("brelse: page missing\n"); 972 } 973 #endif 974 bp->b_pages[j] = m; 975 } 976 } 977 978 if ((bp->b_flags & B_INVAL) == 0) { 979 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 980 } 981 } 982 if (bp->b_flags & (B_NOCACHE|B_ERROR)) { 983 int poffset = foff & PAGE_MASK; 984 int presid = resid > (PAGE_SIZE - poffset) ? 985 (PAGE_SIZE - poffset) : resid; 986 987 KASSERT(presid >= 0, ("brelse: extra page")); 988 vm_page_set_invalid(m, poffset, presid); 989 } 990 resid -= PAGE_SIZE - (foff & PAGE_MASK); 991 foff = (foff + PAGE_SIZE) & ~PAGE_MASK; 992 } 993 994 if (bp->b_flags & (B_INVAL | B_RELBUF)) 995 vfs_vmio_release(bp); 996 997 } else if (bp->b_flags & B_VMIO) { 998 999 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1000 vfs_vmio_release(bp); 1001 1002 } 1003 1004 #if !defined(MAX_PERF) 1005 if (bp->b_qindex != QUEUE_NONE) 1006 panic("brelse: free buffer onto another queue???"); 1007 #endif 1008 if (BUF_REFCNT(bp) > 1) { 1009 /* Temporary panic to verify exclusive locking */ 1010 /* This panic goes away when we allow shared refs */ 1011 panic("brelse: multiple refs"); 1012 /* do not release to free list */ 1013 BUF_UNLOCK(bp); 1014 splx(s); 1015 return; 1016 } 1017 1018 /* enqueue */ 1019 1020 /* buffers with no memory */ 1021 if (bp->b_bufsize == 0) { 1022 bp->b_flags |= B_INVAL; 1023 if (bp->b_kvasize) 1024 bp->b_qindex = QUEUE_EMPTYKVA; 1025 else 1026 bp->b_qindex = QUEUE_EMPTY; 1027 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1028 LIST_REMOVE(bp, b_hash); 1029 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1030 bp->b_dev = NODEV; 1031 kvafreespace += bp->b_kvasize; 1032 if (bp->b_kvasize) 1033 kvaspacewakeup(); 1034 /* buffers with junk contents */ 1035 } else if (bp->b_flags & (B_ERROR | B_INVAL | B_NOCACHE | B_RELBUF)) { 1036 bp->b_flags |= B_INVAL; 1037 bp->b_qindex = QUEUE_CLEAN; 1038 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1039 LIST_REMOVE(bp, b_hash); 1040 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1041 bp->b_dev = NODEV; 1042 1043 /* buffers that are locked */ 1044 } else if (bp->b_flags & B_LOCKED) { 1045 bp->b_qindex = QUEUE_LOCKED; 1046 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LOCKED], bp, b_freelist); 1047 1048 /* remaining buffers */ 1049 } else { 1050 switch(bp->b_flags & (B_DELWRI|B_AGE)) { 1051 case B_DELWRI | B_AGE: 1052 bp->b_qindex = QUEUE_DIRTY; 1053 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_DIRTY], bp, b_freelist); 1054 break; 1055 case B_DELWRI: 1056 bp->b_qindex = QUEUE_DIRTY; 1057 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist); 1058 break; 1059 case B_AGE: 1060 bp->b_qindex = QUEUE_CLEAN; 1061 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1062 break; 1063 default: 1064 bp->b_qindex = QUEUE_CLEAN; 1065 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1066 break; 1067 } 1068 } 1069 1070 /* 1071 * If B_INVAL, clear B_DELWRI. We've already placed the buffer 1072 * on the correct queue. 1073 */ 1074 if ((bp->b_flags & (B_INVAL|B_DELWRI)) == (B_INVAL|B_DELWRI)) { 1075 bp->b_flags &= ~B_DELWRI; 1076 --numdirtybuffers; 1077 numdirtywakeup(); 1078 } 1079 1080 runningbufspace -= bp->b_bufsize; 1081 1082 /* 1083 * Fixup numfreebuffers count. The bp is on an appropriate queue 1084 * unless locked. We then bump numfreebuffers if it is not B_DELWRI. 1085 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1086 * if B_INVAL is set ). 1087 */ 1088 1089 if ((bp->b_flags & B_LOCKED) == 0 && !(bp->b_flags & B_DELWRI)) 1090 bufcountwakeup(); 1091 1092 /* 1093 * Something we can maybe free. 1094 */ 1095 1096 if (bp->b_bufsize) 1097 bufspacewakeup(); 1098 1099 /* unlock */ 1100 BUF_UNLOCK(bp); 1101 bp->b_flags &= ~(B_ORDERED | B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1102 splx(s); 1103 } 1104 1105 /* 1106 * Release a buffer back to the appropriate queue but do not try to free 1107 * it. 1108 * 1109 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1110 * biodone() to requeue an async I/O on completion. It is also used when 1111 * known good buffers need to be requeued but we think we may need the data 1112 * again soon. 1113 */ 1114 void 1115 bqrelse(struct buf * bp) 1116 { 1117 int s; 1118 1119 s = splbio(); 1120 1121 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1122 1123 #if !defined(MAX_PERF) 1124 if (bp->b_qindex != QUEUE_NONE) 1125 panic("bqrelse: free buffer onto another queue???"); 1126 #endif 1127 if (BUF_REFCNT(bp) > 1) { 1128 /* do not release to free list */ 1129 panic("bqrelse: multiple refs"); 1130 BUF_UNLOCK(bp); 1131 splx(s); 1132 return; 1133 } 1134 if (bp->b_flags & B_LOCKED) { 1135 bp->b_flags &= ~B_ERROR; 1136 bp->b_qindex = QUEUE_LOCKED; 1137 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LOCKED], bp, b_freelist); 1138 /* buffers with stale but valid contents */ 1139 } else if (bp->b_flags & B_DELWRI) { 1140 bp->b_qindex = QUEUE_DIRTY; 1141 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist); 1142 } else { 1143 bp->b_qindex = QUEUE_CLEAN; 1144 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1145 } 1146 1147 runningbufspace -= bp->b_bufsize; 1148 1149 if ((bp->b_flags & B_LOCKED) == 0 && 1150 ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI))) { 1151 bufcountwakeup(); 1152 } 1153 1154 /* 1155 * Something we can maybe wakeup 1156 */ 1157 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1158 bufspacewakeup(); 1159 1160 /* unlock */ 1161 BUF_UNLOCK(bp); 1162 bp->b_flags &= ~(B_ORDERED | B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1163 splx(s); 1164 } 1165 1166 static void 1167 vfs_vmio_release(bp) 1168 struct buf *bp; 1169 { 1170 int i, s; 1171 vm_page_t m; 1172 1173 s = splvm(); 1174 for (i = 0; i < bp->b_npages; i++) { 1175 m = bp->b_pages[i]; 1176 bp->b_pages[i] = NULL; 1177 /* 1178 * In order to keep page LRU ordering consistent, put 1179 * everything on the inactive queue. 1180 */ 1181 vm_page_unwire(m, 0); 1182 /* 1183 * We don't mess with busy pages, it is 1184 * the responsibility of the process that 1185 * busied the pages to deal with them. 1186 */ 1187 if ((m->flags & PG_BUSY) || (m->busy != 0)) 1188 continue; 1189 1190 if (m->wire_count == 0) { 1191 vm_page_flag_clear(m, PG_ZERO); 1192 /* 1193 * Might as well free the page if we can and it has 1194 * no valid data. 1195 */ 1196 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && m->hold_count == 0) { 1197 vm_page_busy(m); 1198 vm_page_protect(m, VM_PROT_NONE); 1199 vm_page_free(m); 1200 } 1201 } 1202 } 1203 bufspace -= bp->b_bufsize; 1204 vmiospace -= bp->b_bufsize; 1205 runningbufspace -= bp->b_bufsize; 1206 splx(s); 1207 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages); 1208 if (bp->b_bufsize) 1209 bufspacewakeup(); 1210 bp->b_npages = 0; 1211 bp->b_bufsize = 0; 1212 bp->b_flags &= ~B_VMIO; 1213 if (bp->b_vp) 1214 brelvp(bp); 1215 } 1216 1217 /* 1218 * Check to see if a block is currently memory resident. 1219 */ 1220 struct buf * 1221 gbincore(struct vnode * vp, daddr_t blkno) 1222 { 1223 struct buf *bp; 1224 struct bufhashhdr *bh; 1225 1226 bh = bufhash(vp, blkno); 1227 bp = bh->lh_first; 1228 1229 /* Search hash chain */ 1230 while (bp != NULL) { 1231 /* hit */ 1232 if (bp->b_vp == vp && bp->b_lblkno == blkno && 1233 (bp->b_flags & B_INVAL) == 0) { 1234 break; 1235 } 1236 bp = bp->b_hash.le_next; 1237 } 1238 return (bp); 1239 } 1240 1241 /* 1242 * vfs_bio_awrite: 1243 * 1244 * Implement clustered async writes for clearing out B_DELWRI buffers. 1245 * This is much better then the old way of writing only one buffer at 1246 * a time. Note that we may not be presented with the buffers in the 1247 * correct order, so we search for the cluster in both directions. 1248 */ 1249 int 1250 vfs_bio_awrite(struct buf * bp) 1251 { 1252 int i; 1253 int j; 1254 daddr_t lblkno = bp->b_lblkno; 1255 struct vnode *vp = bp->b_vp; 1256 int s; 1257 int ncl; 1258 struct buf *bpa; 1259 int nwritten; 1260 int size; 1261 int maxcl; 1262 1263 s = splbio(); 1264 /* 1265 * right now we support clustered writing only to regular files. If 1266 * we find a clusterable block we could be in the middle of a cluster 1267 * rather then at the beginning. 1268 */ 1269 if ((vp->v_type == VREG) && 1270 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1271 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1272 1273 size = vp->v_mount->mnt_stat.f_iosize; 1274 maxcl = MAXPHYS / size; 1275 1276 for (i = 1; i < maxcl; i++) { 1277 if ((bpa = gbincore(vp, lblkno + i)) && 1278 BUF_REFCNT(bpa) == 0 && 1279 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == 1280 (B_DELWRI | B_CLUSTEROK)) && 1281 (bpa->b_bufsize == size)) { 1282 if ((bpa->b_blkno == bpa->b_lblkno) || 1283 (bpa->b_blkno != 1284 bp->b_blkno + ((i * size) >> DEV_BSHIFT))) 1285 break; 1286 } else { 1287 break; 1288 } 1289 } 1290 for (j = 1; i + j <= maxcl && j <= lblkno; j++) { 1291 if ((bpa = gbincore(vp, lblkno - j)) && 1292 BUF_REFCNT(bpa) == 0 && 1293 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == 1294 (B_DELWRI | B_CLUSTEROK)) && 1295 (bpa->b_bufsize == size)) { 1296 if ((bpa->b_blkno == bpa->b_lblkno) || 1297 (bpa->b_blkno != 1298 bp->b_blkno - ((j * size) >> DEV_BSHIFT))) 1299 break; 1300 } else { 1301 break; 1302 } 1303 } 1304 --j; 1305 ncl = i + j; 1306 /* 1307 * this is a possible cluster write 1308 */ 1309 if (ncl != 1) { 1310 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl); 1311 splx(s); 1312 return nwritten; 1313 } 1314 } 1315 1316 BUF_LOCK(bp, LK_EXCLUSIVE); 1317 bremfree(bp); 1318 bp->b_flags |= B_ASYNC; 1319 1320 splx(s); 1321 /* 1322 * default (old) behavior, writing out only one block 1323 * 1324 * XXX returns b_bufsize instead of b_bcount for nwritten? 1325 */ 1326 nwritten = bp->b_bufsize; 1327 (void) VOP_BWRITE(bp->b_vp, bp); 1328 1329 return nwritten; 1330 } 1331 1332 /* 1333 * getnewbuf: 1334 * 1335 * Find and initialize a new buffer header, freeing up existing buffers 1336 * in the bufqueues as necessary. The new buffer is returned locked. 1337 * 1338 * Important: B_INVAL is not set. If the caller wishes to throw the 1339 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1340 * 1341 * We block if: 1342 * We have insufficient buffer headers 1343 * We have insufficient buffer space 1344 * buffer_map is too fragmented ( space reservation fails ) 1345 * If we have to flush dirty buffers ( but we try to avoid this ) 1346 * 1347 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1348 * Instead we ask the buf daemon to do it for us. We attempt to 1349 * avoid piecemeal wakeups of the pageout daemon. 1350 */ 1351 1352 static struct buf * 1353 getnewbuf(int slpflag, int slptimeo, int size, int maxsize) 1354 { 1355 struct buf *bp; 1356 struct buf *nbp; 1357 struct buf *dbp; 1358 int outofspace; 1359 int nqindex; 1360 int defrag = 0; 1361 1362 ++getnewbufcalls; 1363 --getnewbufrestarts; 1364 restart: 1365 ++getnewbufrestarts; 1366 1367 /* 1368 * Calculate whether we are out of buffer space. This state is 1369 * recalculated on every restart. If we are out of space, we 1370 * have to turn off defragmentation. Setting defrag to -1 when 1371 * outofspace is positive means "defrag while freeing buffers". 1372 * The looping conditional will be muffed up if defrag is left 1373 * positive when outofspace is positive. 1374 */ 1375 1376 dbp = NULL; 1377 outofspace = 0; 1378 if (bufspace >= hibufspace) { 1379 if ((curproc && (curproc->p_flag & P_BUFEXHAUST) == 0) || 1380 bufspace >= maxbufspace) { 1381 outofspace = 1; 1382 if (defrag > 0) 1383 defrag = -1; 1384 } 1385 } 1386 1387 /* 1388 * defrag state is semi-persistant. 1 means we are flagged for 1389 * defragging. -1 means we actually defragged something. 1390 */ 1391 /* nop */ 1392 1393 /* 1394 * Setup for scan. If we do not have enough free buffers, 1395 * we setup a degenerate case that immediately fails. Note 1396 * that if we are specially marked process, we are allowed to 1397 * dip into our reserves. 1398 * 1399 * Normally we want to find an EMPTYKVA buffer. That is, a 1400 * buffer with kva already allocated. If there are no EMPTYKVA 1401 * buffers we back up to the truely EMPTY buffers. When defragging 1402 * we do not bother backing up since we have to locate buffers with 1403 * kva to defrag. If we are out of space we skip both EMPTY and 1404 * EMPTYKVA and dig right into the CLEAN queue. 1405 * 1406 * In this manner we avoid scanning unnecessary buffers. It is very 1407 * important for us to do this because the buffer cache is almost 1408 * constantly out of space or in need of defragmentation. 1409 */ 1410 1411 if (curproc && (curproc->p_flag & P_BUFEXHAUST) == 0 && 1412 numfreebuffers < lofreebuffers) { 1413 nqindex = QUEUE_CLEAN; 1414 nbp = NULL; 1415 } else { 1416 nqindex = QUEUE_EMPTYKVA; 1417 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 1418 if (nbp == NULL) { 1419 if (defrag <= 0) { 1420 nqindex = QUEUE_EMPTY; 1421 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1422 } 1423 } 1424 if (outofspace || nbp == NULL) { 1425 nqindex = QUEUE_CLEAN; 1426 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 1427 } 1428 } 1429 1430 /* 1431 * Run scan, possibly freeing data and/or kva mappings on the fly 1432 * depending. 1433 */ 1434 1435 while ((bp = nbp) != NULL) { 1436 int qindex = nqindex; 1437 1438 /* 1439 * Calculate next bp ( we can only use it if we do not block 1440 * or do other fancy things ). 1441 */ 1442 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 1443 switch(qindex) { 1444 case QUEUE_EMPTY: 1445 nqindex = QUEUE_EMPTYKVA; 1446 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]))) 1447 break; 1448 /* fall through */ 1449 case QUEUE_EMPTYKVA: 1450 nqindex = QUEUE_CLEAN; 1451 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]))) 1452 break; 1453 /* fall through */ 1454 case QUEUE_CLEAN: 1455 /* 1456 * nbp is NULL. 1457 */ 1458 break; 1459 } 1460 } 1461 1462 /* 1463 * Sanity Checks 1464 */ 1465 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp)); 1466 1467 /* 1468 * Note: we no longer distinguish between VMIO and non-VMIO 1469 * buffers. 1470 */ 1471 1472 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); 1473 1474 /* 1475 * If we are defragging and the buffer isn't useful for fixing 1476 * that problem we continue. If we are out of space and the 1477 * buffer isn't useful for fixing that problem we continue. 1478 */ 1479 1480 if (defrag > 0 && bp->b_kvasize == 0) 1481 continue; 1482 if (outofspace > 0 && bp->b_bufsize == 0) 1483 continue; 1484 1485 /* 1486 * Start freeing the bp. This is somewhat involved. nbp 1487 * remains valid only for QUEUE_EMPTY[KVA] bp's. 1488 */ 1489 1490 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) 1491 panic("getnewbuf: locked buf"); 1492 bremfree(bp); 1493 1494 if (qindex == QUEUE_CLEAN) { 1495 if (bp->b_flags & B_VMIO) { 1496 bp->b_flags &= ~B_ASYNC; 1497 vfs_vmio_release(bp); 1498 } 1499 if (bp->b_vp) 1500 brelvp(bp); 1501 } 1502 1503 /* 1504 * NOTE: nbp is now entirely invalid. We can only restart 1505 * the scan from this point on. 1506 * 1507 * Get the rest of the buffer freed up. b_kva* is still 1508 * valid after this operation. 1509 */ 1510 1511 if (bp->b_rcred != NOCRED) { 1512 crfree(bp->b_rcred); 1513 bp->b_rcred = NOCRED; 1514 } 1515 if (bp->b_wcred != NOCRED) { 1516 crfree(bp->b_wcred); 1517 bp->b_wcred = NOCRED; 1518 } 1519 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_deallocate) 1520 (*bioops.io_deallocate)(bp); 1521 LIST_REMOVE(bp, b_hash); 1522 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1523 1524 if (bp->b_bufsize) 1525 allocbuf(bp, 0); 1526 1527 bp->b_flags = 0; 1528 bp->b_dev = NODEV; 1529 bp->b_vp = NULL; 1530 bp->b_blkno = bp->b_lblkno = 0; 1531 bp->b_offset = NOOFFSET; 1532 bp->b_iodone = 0; 1533 bp->b_error = 0; 1534 bp->b_resid = 0; 1535 bp->b_bcount = 0; 1536 bp->b_npages = 0; 1537 bp->b_dirtyoff = bp->b_dirtyend = 0; 1538 1539 LIST_INIT(&bp->b_dep); 1540 1541 /* 1542 * Ok, now that we have a free buffer, if we are defragging 1543 * we have to recover the kvaspace. If we are out of space 1544 * we have to free the buffer (which we just did), but we 1545 * do not have to recover kva space unless we hit a defrag 1546 * hicup. Being able to avoid freeing the kva space leads 1547 * to a significant reduction in overhead. 1548 */ 1549 1550 if (defrag > 0) { 1551 defrag = -1; 1552 bp->b_flags |= B_INVAL; 1553 bfreekva(bp); 1554 brelse(bp); 1555 goto restart; 1556 } 1557 1558 if (outofspace > 0) { 1559 outofspace = -1; 1560 bp->b_flags |= B_INVAL; 1561 if (defrag < 0) 1562 bfreekva(bp); 1563 brelse(bp); 1564 goto restart; 1565 } 1566 1567 /* 1568 * We are done 1569 */ 1570 break; 1571 } 1572 1573 /* 1574 * If we exhausted our list, sleep as appropriate. We may have to 1575 * wakeup various daemons and write out some dirty buffers. 1576 * 1577 * Generally we are sleeping due to insufficient buffer space. 1578 */ 1579 1580 if (bp == NULL) { 1581 int flags; 1582 char *waitmsg; 1583 1584 dosleep: 1585 if (defrag > 0) { 1586 flags = VFS_BIO_NEED_KVASPACE; 1587 waitmsg = "nbufkv"; 1588 } else if (outofspace > 0) { 1589 waitmsg = "nbufbs"; 1590 flags = VFS_BIO_NEED_BUFSPACE; 1591 } else { 1592 waitmsg = "newbuf"; 1593 flags = VFS_BIO_NEED_ANY; 1594 } 1595 1596 /* XXX */ 1597 1598 (void) speedup_syncer(); 1599 needsbuffer |= flags; 1600 while (needsbuffer & flags) { 1601 if (tsleep(&needsbuffer, (PRIBIO + 4) | slpflag, 1602 waitmsg, slptimeo)) 1603 return (NULL); 1604 } 1605 } else { 1606 /* 1607 * We finally have a valid bp. We aren't quite out of the 1608 * woods, we still have to reserve kva space. 1609 */ 1610 vm_offset_t addr = 0; 1611 1612 maxsize = (maxsize + PAGE_MASK) & ~PAGE_MASK; 1613 1614 if (maxsize != bp->b_kvasize) { 1615 bfreekva(bp); 1616 1617 if (vm_map_findspace(buffer_map, 1618 vm_map_min(buffer_map), maxsize, &addr)) { 1619 /* 1620 * Uh oh. Buffer map is to fragmented. Try 1621 * to defragment. 1622 */ 1623 if (defrag <= 0) { 1624 defrag = 1; 1625 bp->b_flags |= B_INVAL; 1626 brelse(bp); 1627 goto restart; 1628 } 1629 /* 1630 * Uh oh. We couldn't seem to defragment 1631 */ 1632 bp = NULL; 1633 goto dosleep; 1634 } 1635 } 1636 if (addr) { 1637 vm_map_insert(buffer_map, NULL, 0, 1638 addr, addr + maxsize, 1639 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT); 1640 1641 bp->b_kvabase = (caddr_t) addr; 1642 bp->b_kvasize = maxsize; 1643 } 1644 bp->b_data = bp->b_kvabase; 1645 } 1646 return(bp); 1647 } 1648 1649 /* 1650 * waitfreebuffers: 1651 * 1652 * Wait for sufficient free buffers. Only called from normal processes. 1653 */ 1654 1655 static void 1656 waitfreebuffers(int slpflag, int slptimeo) 1657 { 1658 while (numfreebuffers < hifreebuffers) { 1659 if (numfreebuffers >= hifreebuffers) 1660 break; 1661 needsbuffer |= VFS_BIO_NEED_FREE; 1662 if (tsleep(&needsbuffer, (PRIBIO + 4)|slpflag, "biofre", slptimeo)) 1663 break; 1664 } 1665 } 1666 1667 /* 1668 * buf_daemon: 1669 * 1670 * buffer flushing daemon. Buffers are normally flushed by the 1671 * update daemon but if it cannot keep up this process starts to 1672 * take the load in an attempt to prevent getnewbuf() from blocking. 1673 */ 1674 1675 static struct proc *bufdaemonproc; 1676 static int bd_interval; 1677 static int bd_flushto; 1678 1679 static struct kproc_desc buf_kp = { 1680 "bufdaemon", 1681 buf_daemon, 1682 &bufdaemonproc 1683 }; 1684 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp) 1685 1686 static void 1687 buf_daemon() 1688 { 1689 int s; 1690 /* 1691 * This process is allowed to take the buffer cache to the limit 1692 */ 1693 curproc->p_flag |= P_BUFEXHAUST; 1694 s = splbio(); 1695 1696 bd_interval = 5 * hz; /* dynamically adjusted */ 1697 bd_flushto = hidirtybuffers; /* dynamically adjusted */ 1698 1699 while (TRUE) { 1700 bd_request = 0; 1701 1702 /* 1703 * Do the flush. Limit the number of buffers we flush in one 1704 * go. The failure condition occurs when processes are writing 1705 * buffers faster then we can dispose of them. In this case 1706 * we may be flushing so often that the previous set of flushes 1707 * have not had time to complete, causing us to run out of 1708 * physical buffers and block. 1709 */ 1710 { 1711 int runcount = maxbdrun; 1712 1713 while (numdirtybuffers > bd_flushto && runcount) { 1714 --runcount; 1715 if (flushbufqueues() == 0) 1716 break; 1717 } 1718 } 1719 1720 /* 1721 * If nobody is requesting anything we sleep 1722 */ 1723 if (bd_request == 0) 1724 tsleep(&bd_request, PVM, "psleep", bd_interval); 1725 1726 /* 1727 * We calculate how much to add or subtract from bd_flushto 1728 * and bd_interval based on how far off we are from the 1729 * optimal number of dirty buffers, which is 20% below the 1730 * hidirtybuffers mark. We cannot use hidirtybuffers straight 1731 * because being right on the mark will cause getnewbuf() 1732 * to oscillate our wakeup. 1733 * 1734 * The larger the error in either direction, the more we adjust 1735 * bd_flushto and bd_interval. The time interval is adjusted 1736 * by 2 seconds per whole-buffer-range of error. This is an 1737 * exponential convergence algorithm, with large errors 1738 * producing large changes and small errors producing small 1739 * changes. 1740 */ 1741 1742 { 1743 int brange = hidirtybuffers - lodirtybuffers; 1744 int middb = hidirtybuffers - brange / 5; 1745 int deltabuf = middb - numdirtybuffers; 1746 1747 bd_flushto += deltabuf / 20; 1748 bd_interval += deltabuf * (2 * hz) / (brange * 1); 1749 } 1750 if (bd_flushto < lodirtybuffers) 1751 bd_flushto = lodirtybuffers; 1752 if (bd_flushto > hidirtybuffers) 1753 bd_flushto = hidirtybuffers; 1754 if (bd_interval < hz / 10) 1755 bd_interval = hz / 10; 1756 if (bd_interval > 5 * hz) 1757 bd_interval = 5 * hz; 1758 } 1759 } 1760 1761 /* 1762 * flushbufqueues: 1763 * 1764 * Try to flush a buffer in the dirty queue. We must be careful to 1765 * free up B_INVAL buffers instead of write them, which NFS is 1766 * particularly sensitive to. 1767 */ 1768 1769 static int 1770 flushbufqueues(void) 1771 { 1772 struct buf *bp; 1773 int r = 0; 1774 1775 bp = TAILQ_FIRST(&bufqueues[QUEUE_DIRTY]); 1776 1777 while (bp) { 1778 KASSERT((bp->b_flags & B_DELWRI), ("unexpected clean buffer %p", bp)); 1779 if ((bp->b_flags & B_DELWRI) != 0) { 1780 if (bp->b_flags & B_INVAL) { 1781 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) 1782 panic("flushbufqueues: locked buf"); 1783 bremfree(bp); 1784 brelse(bp); 1785 ++r; 1786 break; 1787 } 1788 vfs_bio_awrite(bp); 1789 ++r; 1790 break; 1791 } 1792 bp = TAILQ_NEXT(bp, b_freelist); 1793 } 1794 return(r); 1795 } 1796 1797 /* 1798 * Check to see if a block is currently memory resident. 1799 */ 1800 struct buf * 1801 incore(struct vnode * vp, daddr_t blkno) 1802 { 1803 struct buf *bp; 1804 1805 int s = splbio(); 1806 bp = gbincore(vp, blkno); 1807 splx(s); 1808 return (bp); 1809 } 1810 1811 /* 1812 * Returns true if no I/O is needed to access the 1813 * associated VM object. This is like incore except 1814 * it also hunts around in the VM system for the data. 1815 */ 1816 1817 int 1818 inmem(struct vnode * vp, daddr_t blkno) 1819 { 1820 vm_object_t obj; 1821 vm_offset_t toff, tinc, size; 1822 vm_page_t m; 1823 vm_ooffset_t off; 1824 1825 if (incore(vp, blkno)) 1826 return 1; 1827 if (vp->v_mount == NULL) 1828 return 0; 1829 if ((vp->v_object == NULL) || (vp->v_flag & VOBJBUF) == 0) 1830 return 0; 1831 1832 obj = vp->v_object; 1833 size = PAGE_SIZE; 1834 if (size > vp->v_mount->mnt_stat.f_iosize) 1835 size = vp->v_mount->mnt_stat.f_iosize; 1836 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 1837 1838 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 1839 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 1840 if (!m) 1841 return 0; 1842 tinc = size; 1843 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 1844 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 1845 if (vm_page_is_valid(m, 1846 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 1847 return 0; 1848 } 1849 return 1; 1850 } 1851 1852 /* 1853 * vfs_setdirty: 1854 * 1855 * Sets the dirty range for a buffer based on the status of the dirty 1856 * bits in the pages comprising the buffer. 1857 * 1858 * The range is limited to the size of the buffer. 1859 * 1860 * This routine is primarily used by NFS, but is generalized for the 1861 * B_VMIO case. 1862 */ 1863 static void 1864 vfs_setdirty(struct buf *bp) 1865 { 1866 int i; 1867 vm_object_t object; 1868 1869 /* 1870 * Degenerate case - empty buffer 1871 */ 1872 1873 if (bp->b_bufsize == 0) 1874 return; 1875 1876 /* 1877 * We qualify the scan for modified pages on whether the 1878 * object has been flushed yet. The OBJ_WRITEABLE flag 1879 * is not cleared simply by protecting pages off. 1880 */ 1881 1882 if ((bp->b_flags & B_VMIO) == 0) 1883 return; 1884 1885 object = bp->b_pages[0]->object; 1886 1887 if ((object->flags & OBJ_WRITEABLE) && !(object->flags & OBJ_MIGHTBEDIRTY)) 1888 printf("Warning: object %p writeable but not mightbedirty\n", object); 1889 if (!(object->flags & OBJ_WRITEABLE) && (object->flags & OBJ_MIGHTBEDIRTY)) 1890 printf("Warning: object %p mightbedirty but not writeable\n", object); 1891 1892 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) { 1893 vm_offset_t boffset; 1894 vm_offset_t eoffset; 1895 1896 /* 1897 * test the pages to see if they have been modified directly 1898 * by users through the VM system. 1899 */ 1900 for (i = 0; i < bp->b_npages; i++) { 1901 vm_page_flag_clear(bp->b_pages[i], PG_ZERO); 1902 vm_page_test_dirty(bp->b_pages[i]); 1903 } 1904 1905 /* 1906 * Calculate the encompassing dirty range, boffset and eoffset, 1907 * (eoffset - boffset) bytes. 1908 */ 1909 1910 for (i = 0; i < bp->b_npages; i++) { 1911 if (bp->b_pages[i]->dirty) 1912 break; 1913 } 1914 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 1915 1916 for (i = bp->b_npages - 1; i >= 0; --i) { 1917 if (bp->b_pages[i]->dirty) { 1918 break; 1919 } 1920 } 1921 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 1922 1923 /* 1924 * Fit it to the buffer. 1925 */ 1926 1927 if (eoffset > bp->b_bcount) 1928 eoffset = bp->b_bcount; 1929 1930 /* 1931 * If we have a good dirty range, merge with the existing 1932 * dirty range. 1933 */ 1934 1935 if (boffset < eoffset) { 1936 if (bp->b_dirtyoff > boffset) 1937 bp->b_dirtyoff = boffset; 1938 if (bp->b_dirtyend < eoffset) 1939 bp->b_dirtyend = eoffset; 1940 } 1941 } 1942 } 1943 1944 /* 1945 * getblk: 1946 * 1947 * Get a block given a specified block and offset into a file/device. 1948 * The buffers B_DONE bit will be cleared on return, making it almost 1949 * ready for an I/O initiation. B_INVAL may or may not be set on 1950 * return. The caller should clear B_INVAL prior to initiating a 1951 * READ. 1952 * 1953 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 1954 * an existing buffer. 1955 * 1956 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 1957 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 1958 * and then cleared based on the backing VM. If the previous buffer is 1959 * non-0-sized but invalid, B_CACHE will be cleared. 1960 * 1961 * If getblk() must create a new buffer, the new buffer is returned with 1962 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 1963 * case it is returned with B_INVAL clear and B_CACHE set based on the 1964 * backing VM. 1965 * 1966 * getblk() also forces a VOP_BWRITE() for any B_DELWRI buffer whos 1967 * B_CACHE bit is clear. 1968 * 1969 * What this means, basically, is that the caller should use B_CACHE to 1970 * determine whether the buffer is fully valid or not and should clear 1971 * B_INVAL prior to issuing a read. If the caller intends to validate 1972 * the buffer by loading its data area with something, the caller needs 1973 * to clear B_INVAL. If the caller does this without issuing an I/O, 1974 * the caller should set B_CACHE ( as an optimization ), else the caller 1975 * should issue the I/O and biodone() will set B_CACHE if the I/O was 1976 * a write attempt or if it was a successfull read. If the caller 1977 * intends to issue a READ, the caller must clear B_INVAL and B_ERROR 1978 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 1979 */ 1980 struct buf * 1981 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo) 1982 { 1983 struct buf *bp; 1984 int s; 1985 struct bufhashhdr *bh; 1986 1987 #if !defined(MAX_PERF) 1988 if (size > MAXBSIZE) 1989 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 1990 #endif 1991 1992 s = splbio(); 1993 loop: 1994 /* 1995 * Block if we are low on buffers. Certain processes are allowed 1996 * to completely exhaust the buffer cache. 1997 * 1998 * If this check ever becomes a bottleneck it may be better to 1999 * move it into the else, when gbincore() fails. At the moment 2000 * it isn't a problem. 2001 */ 2002 if (!curproc || (curproc->p_flag & P_BUFEXHAUST)) { 2003 if (numfreebuffers == 0) { 2004 if (!curproc) 2005 return NULL; 2006 needsbuffer |= VFS_BIO_NEED_ANY; 2007 tsleep(&needsbuffer, (PRIBIO + 4) | slpflag, "newbuf", 2008 slptimeo); 2009 } 2010 } else if (numfreebuffers < lofreebuffers) { 2011 waitfreebuffers(slpflag, slptimeo); 2012 } 2013 2014 if ((bp = gbincore(vp, blkno))) { 2015 /* 2016 * Buffer is in-core. If the buffer is not busy, it must 2017 * be on a queue. 2018 */ 2019 2020 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) { 2021 if (BUF_TIMELOCK(bp, LK_EXCLUSIVE | LK_SLEEPFAIL, 2022 "getblk", slpflag, slptimeo) == ENOLCK) 2023 goto loop; 2024 splx(s); 2025 return (struct buf *) NULL; 2026 } 2027 2028 /* 2029 * The buffer is locked. B_CACHE is cleared if the buffer is 2030 * invalid. Ohterwise, for a non-VMIO buffer, B_CACHE is set 2031 * and for a VMIO buffer B_CACHE is adjusted according to the 2032 * backing VM cache. 2033 */ 2034 if (bp->b_flags & B_INVAL) 2035 bp->b_flags &= ~B_CACHE; 2036 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 2037 bp->b_flags |= B_CACHE; 2038 bremfree(bp); 2039 2040 /* 2041 * check for size inconsistancies for non-VMIO case. 2042 */ 2043 2044 if (bp->b_bcount != size) { 2045 if ((bp->b_flags & B_VMIO) == 0 || 2046 (size > bp->b_kvasize)) { 2047 if (bp->b_flags & B_DELWRI) { 2048 bp->b_flags |= B_NOCACHE; 2049 VOP_BWRITE(bp->b_vp, bp); 2050 } else { 2051 if ((bp->b_flags & B_VMIO) && 2052 (LIST_FIRST(&bp->b_dep) == NULL)) { 2053 bp->b_flags |= B_RELBUF; 2054 brelse(bp); 2055 } else { 2056 bp->b_flags |= B_NOCACHE; 2057 VOP_BWRITE(bp->b_vp, bp); 2058 } 2059 } 2060 goto loop; 2061 } 2062 } 2063 2064 /* 2065 * If the size is inconsistant in the VMIO case, we can resize 2066 * the buffer. This might lead to B_CACHE getting set or 2067 * cleared. If the size has not changed, B_CACHE remains 2068 * unchanged from its previous state. 2069 */ 2070 2071 if (bp->b_bcount != size) 2072 allocbuf(bp, size); 2073 2074 KASSERT(bp->b_offset != NOOFFSET, 2075 ("getblk: no buffer offset")); 2076 2077 /* 2078 * A buffer with B_DELWRI set and B_CACHE clear must 2079 * be committed before we can return the buffer in 2080 * order to prevent the caller from issuing a read 2081 * ( due to B_CACHE not being set ) and overwriting 2082 * it. 2083 * 2084 * Most callers, including NFS and FFS, need this to 2085 * operate properly either because they assume they 2086 * can issue a read if B_CACHE is not set, or because 2087 * ( for example ) an uncached B_DELWRI might loop due 2088 * to softupdates re-dirtying the buffer. In the latter 2089 * case, B_CACHE is set after the first write completes, 2090 * preventing further loops. 2091 */ 2092 2093 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 2094 VOP_BWRITE(bp->b_vp, bp); 2095 goto loop; 2096 } 2097 2098 splx(s); 2099 bp->b_flags &= ~B_DONE; 2100 } else { 2101 /* 2102 * Buffer is not in-core, create new buffer. The buffer 2103 * returned by getnewbuf() is locked. Note that the returned 2104 * buffer is also considered valid (not marked B_INVAL). 2105 */ 2106 int bsize, maxsize, vmio; 2107 off_t offset; 2108 2109 if (vp->v_type == VBLK) 2110 bsize = DEV_BSIZE; 2111 else if (vp->v_mountedhere) 2112 bsize = vp->v_mountedhere->mnt_stat.f_iosize; 2113 else if (vp->v_mount) 2114 bsize = vp->v_mount->mnt_stat.f_iosize; 2115 else 2116 bsize = size; 2117 2118 offset = (off_t)blkno * bsize; 2119 vmio = (vp->v_object != 0) && (vp->v_flag & VOBJBUF); 2120 maxsize = vmio ? size + (offset & PAGE_MASK) : size; 2121 maxsize = imax(maxsize, bsize); 2122 2123 if ((bp = getnewbuf(slpflag, slptimeo, size, maxsize)) == NULL) { 2124 if (slpflag || slptimeo) { 2125 splx(s); 2126 return NULL; 2127 } 2128 goto loop; 2129 } 2130 2131 /* 2132 * This code is used to make sure that a buffer is not 2133 * created while the getnewbuf routine is blocked. 2134 * This can be a problem whether the vnode is locked or not. 2135 * If the buffer is created out from under us, we have to 2136 * throw away the one we just created. There is now window 2137 * race because we are safely running at splbio() from the 2138 * point of the duplicate buffer creation through to here, 2139 * and we've locked the buffer. 2140 */ 2141 if (gbincore(vp, blkno)) { 2142 bp->b_flags |= B_INVAL; 2143 brelse(bp); 2144 goto loop; 2145 } 2146 2147 /* 2148 * Insert the buffer into the hash, so that it can 2149 * be found by incore. 2150 */ 2151 bp->b_blkno = bp->b_lblkno = blkno; 2152 bp->b_offset = offset; 2153 2154 bgetvp(vp, bp); 2155 LIST_REMOVE(bp, b_hash); 2156 bh = bufhash(vp, blkno); 2157 LIST_INSERT_HEAD(bh, bp, b_hash); 2158 2159 /* 2160 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 2161 * buffer size starts out as 0, B_CACHE will be set by 2162 * allocbuf() for the VMIO case prior to it testing the 2163 * backing store for validity. 2164 */ 2165 2166 if (vmio) { 2167 bp->b_flags |= B_VMIO; 2168 #if defined(VFS_BIO_DEBUG) 2169 if (vp->v_type != VREG && vp->v_type != VBLK) 2170 printf("getblk: vmioing file type %d???\n", vp->v_type); 2171 #endif 2172 } else { 2173 bp->b_flags &= ~B_VMIO; 2174 } 2175 2176 allocbuf(bp, size); 2177 2178 splx(s); 2179 bp->b_flags &= ~B_DONE; 2180 } 2181 return (bp); 2182 } 2183 2184 /* 2185 * Get an empty, disassociated buffer of given size. The buffer is initially 2186 * set to B_INVAL. 2187 */ 2188 struct buf * 2189 geteblk(int size) 2190 { 2191 struct buf *bp; 2192 int s; 2193 2194 s = splbio(); 2195 while ((bp = getnewbuf(0, 0, size, MAXBSIZE)) == 0); 2196 splx(s); 2197 allocbuf(bp, size); 2198 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 2199 return (bp); 2200 } 2201 2202 2203 /* 2204 * This code constitutes the buffer memory from either anonymous system 2205 * memory (in the case of non-VMIO operations) or from an associated 2206 * VM object (in the case of VMIO operations). This code is able to 2207 * resize a buffer up or down. 2208 * 2209 * Note that this code is tricky, and has many complications to resolve 2210 * deadlock or inconsistant data situations. Tread lightly!!! 2211 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 2212 * the caller. Calling this code willy nilly can result in the loss of data. 2213 * 2214 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 2215 * B_CACHE for the non-VMIO case. 2216 */ 2217 2218 int 2219 allocbuf(struct buf *bp, int size) 2220 { 2221 int newbsize, mbsize; 2222 int i; 2223 2224 #if !defined(MAX_PERF) 2225 if (BUF_REFCNT(bp) == 0) 2226 panic("allocbuf: buffer not busy"); 2227 2228 if (bp->b_kvasize < size) 2229 panic("allocbuf: buffer too small"); 2230 #endif 2231 2232 if ((bp->b_flags & B_VMIO) == 0) { 2233 caddr_t origbuf; 2234 int origbufsize; 2235 /* 2236 * Just get anonymous memory from the kernel. Don't 2237 * mess with B_CACHE. 2238 */ 2239 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2240 #if !defined(NO_B_MALLOC) 2241 if (bp->b_flags & B_MALLOC) 2242 newbsize = mbsize; 2243 else 2244 #endif 2245 newbsize = round_page(size); 2246 2247 if (newbsize < bp->b_bufsize) { 2248 #if !defined(NO_B_MALLOC) 2249 /* 2250 * malloced buffers are not shrunk 2251 */ 2252 if (bp->b_flags & B_MALLOC) { 2253 if (newbsize) { 2254 bp->b_bcount = size; 2255 } else { 2256 free(bp->b_data, M_BIOBUF); 2257 bufspace -= bp->b_bufsize; 2258 bufmallocspace -= bp->b_bufsize; 2259 runningbufspace -= bp->b_bufsize; 2260 if (bp->b_bufsize) 2261 bufspacewakeup(); 2262 bp->b_data = bp->b_kvabase; 2263 bp->b_bufsize = 0; 2264 bp->b_bcount = 0; 2265 bp->b_flags &= ~B_MALLOC; 2266 } 2267 return 1; 2268 } 2269 #endif 2270 vm_hold_free_pages( 2271 bp, 2272 (vm_offset_t) bp->b_data + newbsize, 2273 (vm_offset_t) bp->b_data + bp->b_bufsize); 2274 } else if (newbsize > bp->b_bufsize) { 2275 #if !defined(NO_B_MALLOC) 2276 /* 2277 * We only use malloced memory on the first allocation. 2278 * and revert to page-allocated memory when the buffer 2279 * grows. 2280 */ 2281 if ( (bufmallocspace < maxbufmallocspace) && 2282 (bp->b_bufsize == 0) && 2283 (mbsize <= PAGE_SIZE/2)) { 2284 2285 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 2286 bp->b_bufsize = mbsize; 2287 bp->b_bcount = size; 2288 bp->b_flags |= B_MALLOC; 2289 bufspace += mbsize; 2290 bufmallocspace += mbsize; 2291 runningbufspace += bp->b_bufsize; 2292 return 1; 2293 } 2294 #endif 2295 origbuf = NULL; 2296 origbufsize = 0; 2297 #if !defined(NO_B_MALLOC) 2298 /* 2299 * If the buffer is growing on its other-than-first allocation, 2300 * then we revert to the page-allocation scheme. 2301 */ 2302 if (bp->b_flags & B_MALLOC) { 2303 origbuf = bp->b_data; 2304 origbufsize = bp->b_bufsize; 2305 bp->b_data = bp->b_kvabase; 2306 bufspace -= bp->b_bufsize; 2307 bufmallocspace -= bp->b_bufsize; 2308 runningbufspace -= bp->b_bufsize; 2309 if (bp->b_bufsize) 2310 bufspacewakeup(); 2311 bp->b_bufsize = 0; 2312 bp->b_flags &= ~B_MALLOC; 2313 newbsize = round_page(newbsize); 2314 } 2315 #endif 2316 vm_hold_load_pages( 2317 bp, 2318 (vm_offset_t) bp->b_data + bp->b_bufsize, 2319 (vm_offset_t) bp->b_data + newbsize); 2320 #if !defined(NO_B_MALLOC) 2321 if (origbuf) { 2322 bcopy(origbuf, bp->b_data, origbufsize); 2323 free(origbuf, M_BIOBUF); 2324 } 2325 #endif 2326 } 2327 } else { 2328 vm_page_t m; 2329 int desiredpages; 2330 2331 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2332 desiredpages = (size == 0) ? 0 : 2333 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 2334 2335 #if !defined(NO_B_MALLOC) 2336 if (bp->b_flags & B_MALLOC) 2337 panic("allocbuf: VMIO buffer can't be malloced"); 2338 #endif 2339 /* 2340 * Set B_CACHE initially if buffer is 0 length or will become 2341 * 0-length. 2342 */ 2343 if (size == 0 || bp->b_bufsize == 0) 2344 bp->b_flags |= B_CACHE; 2345 2346 if (newbsize < bp->b_bufsize) { 2347 /* 2348 * DEV_BSIZE aligned new buffer size is less then the 2349 * DEV_BSIZE aligned existing buffer size. Figure out 2350 * if we have to remove any pages. 2351 */ 2352 if (desiredpages < bp->b_npages) { 2353 for (i = desiredpages; i < bp->b_npages; i++) { 2354 /* 2355 * the page is not freed here -- it 2356 * is the responsibility of 2357 * vnode_pager_setsize 2358 */ 2359 m = bp->b_pages[i]; 2360 KASSERT(m != bogus_page, 2361 ("allocbuf: bogus page found")); 2362 while (vm_page_sleep_busy(m, TRUE, "biodep")) 2363 ; 2364 2365 bp->b_pages[i] = NULL; 2366 vm_page_unwire(m, 0); 2367 } 2368 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) + 2369 (desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages)); 2370 bp->b_npages = desiredpages; 2371 } 2372 } else if (size > bp->b_bcount) { 2373 /* 2374 * We are growing the buffer, possibly in a 2375 * byte-granular fashion. 2376 */ 2377 struct vnode *vp; 2378 vm_object_t obj; 2379 vm_offset_t toff; 2380 vm_offset_t tinc; 2381 2382 /* 2383 * Step 1, bring in the VM pages from the object, 2384 * allocating them if necessary. We must clear 2385 * B_CACHE if these pages are not valid for the 2386 * range covered by the buffer. 2387 */ 2388 2389 vp = bp->b_vp; 2390 obj = vp->v_object; 2391 2392 while (bp->b_npages < desiredpages) { 2393 vm_page_t m; 2394 vm_pindex_t pi; 2395 2396 pi = OFF_TO_IDX(bp->b_offset) + bp->b_npages; 2397 if ((m = vm_page_lookup(obj, pi)) == NULL) { 2398 m = vm_page_alloc(obj, pi, VM_ALLOC_NORMAL); 2399 if (m == NULL) { 2400 VM_WAIT; 2401 vm_pageout_deficit += desiredpages - bp->b_npages; 2402 } else { 2403 vm_page_wire(m); 2404 vm_page_wakeup(m); 2405 bp->b_flags &= ~B_CACHE; 2406 bp->b_pages[bp->b_npages] = m; 2407 ++bp->b_npages; 2408 } 2409 continue; 2410 } 2411 2412 /* 2413 * We found a page. If we have to sleep on it, 2414 * retry because it might have gotten freed out 2415 * from under us. 2416 * 2417 * We can only test PG_BUSY here. Blocking on 2418 * m->busy might lead to a deadlock: 2419 * 2420 * vm_fault->getpages->cluster_read->allocbuf 2421 * 2422 */ 2423 2424 if (vm_page_sleep_busy(m, FALSE, "pgtblk")) 2425 continue; 2426 2427 /* 2428 * We have a good page. Should we wakeup the 2429 * page daemon? 2430 */ 2431 if ((curproc != pageproc) && 2432 ((m->queue - m->pc) == PQ_CACHE) && 2433 ((cnt.v_free_count + cnt.v_cache_count) < 2434 (cnt.v_free_min + cnt.v_cache_min))) { 2435 pagedaemon_wakeup(); 2436 } 2437 vm_page_flag_clear(m, PG_ZERO); 2438 vm_page_wire(m); 2439 bp->b_pages[bp->b_npages] = m; 2440 ++bp->b_npages; 2441 } 2442 2443 /* 2444 * Step 2. We've loaded the pages into the buffer, 2445 * we have to figure out if we can still have B_CACHE 2446 * set. Note that B_CACHE is set according to the 2447 * byte-granular range ( bcount and size ), new the 2448 * aligned range ( newbsize ). 2449 * 2450 * The VM test is against m->valid, which is DEV_BSIZE 2451 * aligned. Needless to say, the validity of the data 2452 * needs to also be DEV_BSIZE aligned. Note that this 2453 * fails with NFS if the server or some other client 2454 * extends the file's EOF. If our buffer is resized, 2455 * B_CACHE may remain set! XXX 2456 */ 2457 2458 toff = bp->b_bcount; 2459 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 2460 2461 while ((bp->b_flags & B_CACHE) && toff < size) { 2462 vm_pindex_t pi; 2463 2464 if (tinc > (size - toff)) 2465 tinc = size - toff; 2466 2467 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 2468 PAGE_SHIFT; 2469 2470 vfs_buf_test_cache( 2471 bp, 2472 bp->b_offset, 2473 toff, 2474 tinc, 2475 bp->b_pages[pi] 2476 ); 2477 toff += tinc; 2478 tinc = PAGE_SIZE; 2479 } 2480 2481 /* 2482 * Step 3, fixup the KVM pmap. Remember that 2483 * bp->b_data is relative to bp->b_offset, but 2484 * bp->b_offset may be offset into the first page. 2485 */ 2486 2487 bp->b_data = (caddr_t) 2488 trunc_page((vm_offset_t)bp->b_data); 2489 pmap_qenter( 2490 (vm_offset_t)bp->b_data, 2491 bp->b_pages, 2492 bp->b_npages 2493 ); 2494 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 2495 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 2496 } 2497 } 2498 if (bp->b_flags & B_VMIO) 2499 vmiospace += (newbsize - bp->b_bufsize); 2500 bufspace += (newbsize - bp->b_bufsize); 2501 runningbufspace += (newbsize - bp->b_bufsize); 2502 if (newbsize < bp->b_bufsize) 2503 bufspacewakeup(); 2504 bp->b_bufsize = newbsize; /* actual buffer allocation */ 2505 bp->b_bcount = size; /* requested buffer size */ 2506 return 1; 2507 } 2508 2509 /* 2510 * biowait: 2511 * 2512 * Wait for buffer I/O completion, returning error status. The buffer 2513 * is left locked and B_DONE on return. B_EINTR is converted into a EINTR 2514 * error and cleared. 2515 */ 2516 int 2517 biowait(register struct buf * bp) 2518 { 2519 int s; 2520 2521 s = splbio(); 2522 while ((bp->b_flags & B_DONE) == 0) { 2523 #if defined(NO_SCHEDULE_MODS) 2524 tsleep(bp, PRIBIO, "biowait", 0); 2525 #else 2526 if (bp->b_flags & B_READ) 2527 tsleep(bp, PRIBIO, "biord", 0); 2528 else 2529 tsleep(bp, PRIBIO, "biowr", 0); 2530 #endif 2531 } 2532 splx(s); 2533 if (bp->b_flags & B_EINTR) { 2534 bp->b_flags &= ~B_EINTR; 2535 return (EINTR); 2536 } 2537 if (bp->b_flags & B_ERROR) { 2538 return (bp->b_error ? bp->b_error : EIO); 2539 } else { 2540 return (0); 2541 } 2542 } 2543 2544 /* 2545 * biodone: 2546 * 2547 * Finish I/O on a buffer, optionally calling a completion function. 2548 * This is usually called from an interrupt so process blocking is 2549 * not allowed. 2550 * 2551 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 2552 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 2553 * assuming B_INVAL is clear. 2554 * 2555 * For the VMIO case, we set B_CACHE if the op was a read and no 2556 * read error occured, or if the op was a write. B_CACHE is never 2557 * set if the buffer is invalid or otherwise uncacheable. 2558 * 2559 * biodone does not mess with B_INVAL, allowing the I/O routine or the 2560 * initiator to leave B_INVAL set to brelse the buffer out of existance 2561 * in the biodone routine. 2562 */ 2563 void 2564 biodone(register struct buf * bp) 2565 { 2566 int s; 2567 2568 s = splbio(); 2569 2570 KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp, BUF_REFCNT(bp))); 2571 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 2572 2573 bp->b_flags |= B_DONE; 2574 2575 if (bp->b_flags & B_FREEBUF) { 2576 brelse(bp); 2577 splx(s); 2578 return; 2579 } 2580 2581 if ((bp->b_flags & B_READ) == 0) { 2582 vwakeup(bp); 2583 } 2584 2585 /* call optional completion function if requested */ 2586 if (bp->b_flags & B_CALL) { 2587 bp->b_flags &= ~B_CALL; 2588 (*bp->b_iodone) (bp); 2589 splx(s); 2590 return; 2591 } 2592 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_complete) 2593 (*bioops.io_complete)(bp); 2594 2595 if (bp->b_flags & B_VMIO) { 2596 int i, resid; 2597 vm_ooffset_t foff; 2598 vm_page_t m; 2599 vm_object_t obj; 2600 int iosize; 2601 struct vnode *vp = bp->b_vp; 2602 2603 obj = vp->v_object; 2604 2605 #if defined(VFS_BIO_DEBUG) 2606 if (vp->v_usecount == 0) { 2607 panic("biodone: zero vnode ref count"); 2608 } 2609 2610 if (vp->v_object == NULL) { 2611 panic("biodone: missing VM object"); 2612 } 2613 2614 if ((vp->v_flag & VOBJBUF) == 0) { 2615 panic("biodone: vnode is not setup for merged cache"); 2616 } 2617 #endif 2618 2619 foff = bp->b_offset; 2620 KASSERT(bp->b_offset != NOOFFSET, 2621 ("biodone: no buffer offset")); 2622 2623 #if !defined(MAX_PERF) 2624 if (!obj) { 2625 panic("biodone: no object"); 2626 } 2627 #endif 2628 #if defined(VFS_BIO_DEBUG) 2629 if (obj->paging_in_progress < bp->b_npages) { 2630 printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n", 2631 obj->paging_in_progress, bp->b_npages); 2632 } 2633 #endif 2634 2635 /* 2636 * Set B_CACHE if the op was a normal read and no error 2637 * occured. B_CACHE is set for writes in the b*write() 2638 * routines. 2639 */ 2640 iosize = bp->b_bcount; 2641 if ((bp->b_flags & (B_READ|B_FREEBUF|B_INVAL|B_NOCACHE|B_ERROR)) == B_READ) { 2642 bp->b_flags |= B_CACHE; 2643 } 2644 2645 for (i = 0; i < bp->b_npages; i++) { 2646 int bogusflag = 0; 2647 m = bp->b_pages[i]; 2648 if (m == bogus_page) { 2649 bogusflag = 1; 2650 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 2651 if (!m) { 2652 #if defined(VFS_BIO_DEBUG) 2653 printf("biodone: page disappeared\n"); 2654 #endif 2655 vm_object_pip_subtract(obj, 1); 2656 bp->b_flags &= ~B_CACHE; 2657 continue; 2658 } 2659 bp->b_pages[i] = m; 2660 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 2661 } 2662 #if defined(VFS_BIO_DEBUG) 2663 if (OFF_TO_IDX(foff) != m->pindex) { 2664 printf( 2665 "biodone: foff(%lu)/m->pindex(%d) mismatch\n", 2666 (unsigned long)foff, m->pindex); 2667 } 2668 #endif 2669 resid = IDX_TO_OFF(m->pindex + 1) - foff; 2670 if (resid > iosize) 2671 resid = iosize; 2672 2673 /* 2674 * In the write case, the valid and clean bits are 2675 * already changed correctly ( see bdwrite() ), so we 2676 * only need to do this here in the read case. 2677 */ 2678 if ((bp->b_flags & B_READ) && !bogusflag && resid > 0) { 2679 vfs_page_set_valid(bp, foff, i, m); 2680 } 2681 vm_page_flag_clear(m, PG_ZERO); 2682 2683 /* 2684 * when debugging new filesystems or buffer I/O methods, this 2685 * is the most common error that pops up. if you see this, you 2686 * have not set the page busy flag correctly!!! 2687 */ 2688 if (m->busy == 0) { 2689 #if !defined(MAX_PERF) 2690 printf("biodone: page busy < 0, " 2691 "pindex: %d, foff: 0x(%x,%x), " 2692 "resid: %d, index: %d\n", 2693 (int) m->pindex, (int)(foff >> 32), 2694 (int) foff & 0xffffffff, resid, i); 2695 #endif 2696 if (vp->v_type != VBLK) 2697 #if !defined(MAX_PERF) 2698 printf(" iosize: %ld, lblkno: %d, flags: 0x%lx, npages: %d\n", 2699 bp->b_vp->v_mount->mnt_stat.f_iosize, 2700 (int) bp->b_lblkno, 2701 bp->b_flags, bp->b_npages); 2702 else 2703 printf(" VDEV, lblkno: %d, flags: 0x%lx, npages: %d\n", 2704 (int) bp->b_lblkno, 2705 bp->b_flags, bp->b_npages); 2706 printf(" valid: 0x%x, dirty: 0x%x, wired: %d\n", 2707 m->valid, m->dirty, m->wire_count); 2708 #endif 2709 panic("biodone: page busy < 0\n"); 2710 } 2711 vm_page_io_finish(m); 2712 vm_object_pip_subtract(obj, 1); 2713 foff += resid; 2714 iosize -= resid; 2715 } 2716 if (obj) 2717 vm_object_pip_wakeupn(obj, 0); 2718 } 2719 /* 2720 * For asynchronous completions, release the buffer now. The brelse 2721 * will do a wakeup there if necessary - so no need to do a wakeup 2722 * here in the async case. The sync case always needs to do a wakeup. 2723 */ 2724 2725 if (bp->b_flags & B_ASYNC) { 2726 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR | B_RELBUF)) != 0) 2727 brelse(bp); 2728 else 2729 bqrelse(bp); 2730 } else { 2731 wakeup(bp); 2732 } 2733 splx(s); 2734 } 2735 2736 /* 2737 * This routine is called in lieu of iodone in the case of 2738 * incomplete I/O. This keeps the busy status for pages 2739 * consistant. 2740 */ 2741 void 2742 vfs_unbusy_pages(struct buf * bp) 2743 { 2744 int i; 2745 2746 if (bp->b_flags & B_VMIO) { 2747 struct vnode *vp = bp->b_vp; 2748 vm_object_t obj = vp->v_object; 2749 2750 for (i = 0; i < bp->b_npages; i++) { 2751 vm_page_t m = bp->b_pages[i]; 2752 2753 if (m == bogus_page) { 2754 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 2755 #if !defined(MAX_PERF) 2756 if (!m) { 2757 panic("vfs_unbusy_pages: page missing\n"); 2758 } 2759 #endif 2760 bp->b_pages[i] = m; 2761 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 2762 } 2763 vm_object_pip_subtract(obj, 1); 2764 vm_page_flag_clear(m, PG_ZERO); 2765 vm_page_io_finish(m); 2766 } 2767 vm_object_pip_wakeupn(obj, 0); 2768 } 2769 } 2770 2771 /* 2772 * vfs_page_set_valid: 2773 * 2774 * Set the valid bits in a page based on the supplied offset. The 2775 * range is restricted to the buffer's size. 2776 * 2777 * This routine is typically called after a read completes. 2778 */ 2779 static void 2780 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m) 2781 { 2782 vm_ooffset_t soff, eoff; 2783 2784 /* 2785 * Start and end offsets in buffer. eoff - soff may not cross a 2786 * page boundry or cross the end of the buffer. The end of the 2787 * buffer, in this case, is our file EOF, not the allocation size 2788 * of the buffer. 2789 */ 2790 soff = off; 2791 eoff = (off + PAGE_SIZE) & ~PAGE_MASK; 2792 if (eoff > bp->b_offset + bp->b_bcount) 2793 eoff = bp->b_offset + bp->b_bcount; 2794 2795 /* 2796 * Set valid range. This is typically the entire buffer and thus the 2797 * entire page. 2798 */ 2799 if (eoff > soff) { 2800 vm_page_set_validclean( 2801 m, 2802 (vm_offset_t) (soff & PAGE_MASK), 2803 (vm_offset_t) (eoff - soff) 2804 ); 2805 } 2806 } 2807 2808 /* 2809 * This routine is called before a device strategy routine. 2810 * It is used to tell the VM system that paging I/O is in 2811 * progress, and treat the pages associated with the buffer 2812 * almost as being PG_BUSY. Also the object paging_in_progress 2813 * flag is handled to make sure that the object doesn't become 2814 * inconsistant. 2815 * 2816 * Since I/O has not been initiated yet, certain buffer flags 2817 * such as B_ERROR or B_INVAL may be in an inconsistant state 2818 * and should be ignored. 2819 */ 2820 void 2821 vfs_busy_pages(struct buf * bp, int clear_modify) 2822 { 2823 int i, bogus; 2824 2825 if (bp->b_flags & B_VMIO) { 2826 struct vnode *vp = bp->b_vp; 2827 vm_object_t obj = vp->v_object; 2828 vm_ooffset_t foff; 2829 2830 foff = bp->b_offset; 2831 KASSERT(bp->b_offset != NOOFFSET, 2832 ("vfs_busy_pages: no buffer offset")); 2833 vfs_setdirty(bp); 2834 2835 retry: 2836 for (i = 0; i < bp->b_npages; i++) { 2837 vm_page_t m = bp->b_pages[i]; 2838 if (vm_page_sleep_busy(m, FALSE, "vbpage")) 2839 goto retry; 2840 } 2841 2842 bogus = 0; 2843 for (i = 0; i < bp->b_npages; i++) { 2844 vm_page_t m = bp->b_pages[i]; 2845 2846 vm_page_flag_clear(m, PG_ZERO); 2847 if ((bp->b_flags & B_CLUSTER) == 0) { 2848 vm_object_pip_add(obj, 1); 2849 vm_page_io_start(m); 2850 } 2851 2852 /* 2853 * When readying a buffer for a read ( i.e 2854 * clear_modify == 0 ), it is important to do 2855 * bogus_page replacement for valid pages in 2856 * partially instantiated buffers. Partially 2857 * instantiated buffers can, in turn, occur when 2858 * reconstituting a buffer from its VM backing store 2859 * base. We only have to do this if B_CACHE is 2860 * clear ( which causes the I/O to occur in the 2861 * first place ). The replacement prevents the read 2862 * I/O from overwriting potentially dirty VM-backed 2863 * pages. XXX bogus page replacement is, uh, bogus. 2864 * It may not work properly with small-block devices. 2865 * We need to find a better way. 2866 */ 2867 2868 vm_page_protect(m, VM_PROT_NONE); 2869 if (clear_modify) 2870 vfs_page_set_valid(bp, foff, i, m); 2871 else if (m->valid == VM_PAGE_BITS_ALL && 2872 (bp->b_flags & B_CACHE) == 0) { 2873 bp->b_pages[i] = bogus_page; 2874 bogus++; 2875 } 2876 foff = (foff + PAGE_SIZE) & ~PAGE_MASK; 2877 } 2878 if (bogus) 2879 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 2880 } 2881 } 2882 2883 /* 2884 * Tell the VM system that the pages associated with this buffer 2885 * are clean. This is used for delayed writes where the data is 2886 * going to go to disk eventually without additional VM intevention. 2887 * 2888 * Note that while we only really need to clean through to b_bcount, we 2889 * just go ahead and clean through to b_bufsize. 2890 */ 2891 static void 2892 vfs_clean_pages(struct buf * bp) 2893 { 2894 int i; 2895 2896 if (bp->b_flags & B_VMIO) { 2897 vm_ooffset_t foff; 2898 2899 foff = bp->b_offset; 2900 KASSERT(bp->b_offset != NOOFFSET, 2901 ("vfs_clean_pages: no buffer offset")); 2902 for (i = 0; i < bp->b_npages; i++) { 2903 vm_page_t m = bp->b_pages[i]; 2904 vm_ooffset_t noff = (foff + PAGE_SIZE) & ~PAGE_MASK; 2905 vm_ooffset_t eoff = noff; 2906 2907 if (eoff > bp->b_offset + bp->b_bufsize) 2908 eoff = bp->b_offset + bp->b_bufsize; 2909 vfs_page_set_valid(bp, foff, i, m); 2910 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 2911 foff = noff; 2912 } 2913 } 2914 } 2915 2916 /* 2917 * vfs_bio_set_validclean: 2918 * 2919 * Set the range within the buffer to valid and clean. The range is 2920 * relative to the beginning of the buffer, b_offset. Note that b_offset 2921 * itself may be offset from the beginning of the first page. 2922 */ 2923 2924 void 2925 vfs_bio_set_validclean(struct buf *bp, int base, int size) 2926 { 2927 if (bp->b_flags & B_VMIO) { 2928 int i; 2929 int n; 2930 2931 /* 2932 * Fixup base to be relative to beginning of first page. 2933 * Set initial n to be the maximum number of bytes in the 2934 * first page that can be validated. 2935 */ 2936 2937 base += (bp->b_offset & PAGE_MASK); 2938 n = PAGE_SIZE - (base & PAGE_MASK); 2939 2940 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 2941 vm_page_t m = bp->b_pages[i]; 2942 2943 if (n > size) 2944 n = size; 2945 2946 vm_page_set_validclean(m, base & PAGE_MASK, n); 2947 base += n; 2948 size -= n; 2949 n = PAGE_SIZE; 2950 } 2951 } 2952 } 2953 2954 /* 2955 * vfs_bio_clrbuf: 2956 * 2957 * clear a buffer. This routine essentially fakes an I/O, so we need 2958 * to clear B_ERROR and B_INVAL. 2959 * 2960 * Note that while we only theoretically need to clear through b_bcount, 2961 * we go ahead and clear through b_bufsize. 2962 */ 2963 2964 void 2965 vfs_bio_clrbuf(struct buf *bp) { 2966 int i, mask = 0; 2967 caddr_t sa, ea; 2968 if ((bp->b_flags & (B_VMIO | B_MALLOC)) == B_VMIO) { 2969 bp->b_flags &= ~(B_INVAL|B_ERROR); 2970 if( (bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 2971 (bp->b_offset & PAGE_MASK) == 0) { 2972 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 2973 if (((bp->b_pages[0]->flags & PG_ZERO) == 0) && 2974 ((bp->b_pages[0]->valid & mask) != mask)) { 2975 bzero(bp->b_data, bp->b_bufsize); 2976 } 2977 bp->b_pages[0]->valid |= mask; 2978 bp->b_resid = 0; 2979 return; 2980 } 2981 ea = sa = bp->b_data; 2982 for(i=0;i<bp->b_npages;i++,sa=ea) { 2983 int j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; 2984 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); 2985 ea = (caddr_t)(vm_offset_t)ulmin( 2986 (u_long)(vm_offset_t)ea, 2987 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); 2988 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 2989 if ((bp->b_pages[i]->valid & mask) == mask) 2990 continue; 2991 if ((bp->b_pages[i]->valid & mask) == 0) { 2992 if ((bp->b_pages[i]->flags & PG_ZERO) == 0) { 2993 bzero(sa, ea - sa); 2994 } 2995 } else { 2996 for (; sa < ea; sa += DEV_BSIZE, j++) { 2997 if (((bp->b_pages[i]->flags & PG_ZERO) == 0) && 2998 (bp->b_pages[i]->valid & (1<<j)) == 0) 2999 bzero(sa, DEV_BSIZE); 3000 } 3001 } 3002 bp->b_pages[i]->valid |= mask; 3003 vm_page_flag_clear(bp->b_pages[i], PG_ZERO); 3004 } 3005 bp->b_resid = 0; 3006 } else { 3007 clrbuf(bp); 3008 } 3009 } 3010 3011 /* 3012 * vm_hold_load_pages and vm_hold_unload pages get pages into 3013 * a buffers address space. The pages are anonymous and are 3014 * not associated with a file object. 3015 */ 3016 void 3017 vm_hold_load_pages(struct buf * bp, vm_offset_t from, vm_offset_t to) 3018 { 3019 vm_offset_t pg; 3020 vm_page_t p; 3021 int index; 3022 3023 to = round_page(to); 3024 from = round_page(from); 3025 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3026 3027 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3028 3029 tryagain: 3030 3031 p = vm_page_alloc(kernel_object, 3032 ((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 3033 VM_ALLOC_NORMAL); 3034 if (!p) { 3035 vm_pageout_deficit += (to - from) >> PAGE_SHIFT; 3036 VM_WAIT; 3037 goto tryagain; 3038 } 3039 vm_page_wire(p); 3040 p->valid = VM_PAGE_BITS_ALL; 3041 vm_page_flag_clear(p, PG_ZERO); 3042 pmap_kenter(pg, VM_PAGE_TO_PHYS(p)); 3043 bp->b_pages[index] = p; 3044 vm_page_wakeup(p); 3045 } 3046 bp->b_npages = index; 3047 } 3048 3049 void 3050 vm_hold_free_pages(struct buf * bp, vm_offset_t from, vm_offset_t to) 3051 { 3052 vm_offset_t pg; 3053 vm_page_t p; 3054 int index, newnpages; 3055 3056 from = round_page(from); 3057 to = round_page(to); 3058 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3059 3060 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3061 p = bp->b_pages[index]; 3062 if (p && (index < bp->b_npages)) { 3063 #if !defined(MAX_PERF) 3064 if (p->busy) { 3065 printf("vm_hold_free_pages: blkno: %d, lblkno: %d\n", 3066 bp->b_blkno, bp->b_lblkno); 3067 } 3068 #endif 3069 bp->b_pages[index] = NULL; 3070 pmap_kremove(pg); 3071 vm_page_busy(p); 3072 vm_page_unwire(p, 0); 3073 vm_page_free(p); 3074 } 3075 } 3076 bp->b_npages = newnpages; 3077 } 3078 3079 3080 #include "opt_ddb.h" 3081 #ifdef DDB 3082 #include <ddb/ddb.h> 3083 3084 DB_SHOW_COMMAND(buffer, db_show_buffer) 3085 { 3086 /* get args */ 3087 struct buf *bp = (struct buf *)addr; 3088 3089 if (!have_addr) { 3090 db_printf("usage: show buffer <addr>\n"); 3091 return; 3092 } 3093 3094 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS); 3095 db_printf("b_error = %d, b_bufsize = %ld, b_bcount = %ld, " 3096 "b_resid = %ld\nb_dev = (%d,%d), b_data = %p, " 3097 "b_blkno = %d, b_pblkno = %d\n", 3098 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 3099 major(bp->b_dev), minor(bp->b_dev), 3100 bp->b_data, bp->b_blkno, bp->b_pblkno); 3101 if (bp->b_npages) { 3102 int i; 3103 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 3104 for (i = 0; i < bp->b_npages; i++) { 3105 vm_page_t m; 3106 m = bp->b_pages[i]; 3107 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 3108 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 3109 if ((i + 1) < bp->b_npages) 3110 db_printf(","); 3111 } 3112 db_printf("\n"); 3113 } 3114 } 3115 #endif /* DDB */ 3116