1 /* 2 * Copyright (c) 1994,1997 John S. Dyson 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice immediately at the beginning of the file, without modification, 10 * this list of conditions, and the following disclaimer. 11 * 2. Absolutely no warranty of function or purpose is made by the author 12 * John S. Dyson. 13 * 14 * $FreeBSD: src/sys/kern/vfs_bio.c,v 1.242.2.20 2003/05/28 18:38:10 alc Exp $ 15 * $DragonFly: src/sys/kern/vfs_bio.c,v 1.30 2004/07/14 03:43:58 hmp Exp $ 16 */ 17 18 /* 19 * this file contains a new buffer I/O scheme implementing a coherent 20 * VM object and buffer cache scheme. Pains have been taken to make 21 * sure that the performance degradation associated with schemes such 22 * as this is not realized. 23 * 24 * Author: John S. Dyson 25 * Significant help during the development and debugging phases 26 * had been provided by David Greenman, also of the FreeBSD core team. 27 * 28 * see man buf(9) for more info. 29 */ 30 31 #include <sys/param.h> 32 #include <sys/systm.h> 33 #include <sys/buf.h> 34 #include <sys/conf.h> 35 #include <sys/eventhandler.h> 36 #include <sys/lock.h> 37 #include <sys/malloc.h> 38 #include <sys/mount.h> 39 #include <sys/kernel.h> 40 #include <sys/kthread.h> 41 #include <sys/proc.h> 42 #include <sys/reboot.h> 43 #include <sys/resourcevar.h> 44 #include <sys/sysctl.h> 45 #include <sys/vmmeter.h> 46 #include <sys/vnode.h> 47 #include <sys/proc.h> 48 #include <vm/vm.h> 49 #include <vm/vm_param.h> 50 #include <vm/vm_kern.h> 51 #include <vm/vm_pageout.h> 52 #include <vm/vm_page.h> 53 #include <vm/vm_object.h> 54 #include <vm/vm_extern.h> 55 #include <vm/vm_map.h> 56 #include <sys/buf2.h> 57 #include <vm/vm_page2.h> 58 59 static MALLOC_DEFINE(M_BIOBUF, "BIO buffer", "BIO buffer"); 60 61 struct bio_ops bioops; /* I/O operation notification */ 62 63 struct buf *buf; /* buffer header pool */ 64 struct swqueue bswlist; 65 66 static void vm_hold_free_pages(struct buf * bp, vm_offset_t from, 67 vm_offset_t to); 68 static void vm_hold_load_pages(struct buf * bp, vm_offset_t from, 69 vm_offset_t to); 70 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, 71 int pageno, vm_page_t m); 72 static void vfs_clean_pages(struct buf * bp); 73 static void vfs_setdirty(struct buf *bp); 74 static void vfs_vmio_release(struct buf *bp); 75 static void vfs_backgroundwritedone(struct buf *bp); 76 static int flushbufqueues(void); 77 78 static int bd_request; 79 80 static void buf_daemon (void); 81 /* 82 * bogus page -- for I/O to/from partially complete buffers 83 * this is a temporary solution to the problem, but it is not 84 * really that bad. it would be better to split the buffer 85 * for input in the case of buffers partially already in memory, 86 * but the code is intricate enough already. 87 */ 88 vm_page_t bogus_page; 89 int vmiodirenable = TRUE; 90 int runningbufspace; 91 struct lwkt_token buftimetoken; /* Interlock on setting prio and timo */ 92 93 static vm_offset_t bogus_offset; 94 95 static int bufspace, maxbufspace, 96 bufmallocspace, maxbufmallocspace, lobufspace, hibufspace; 97 static int bufreusecnt, bufdefragcnt, buffreekvacnt; 98 static int needsbuffer; 99 static int lorunningspace, hirunningspace, runningbufreq; 100 static int numdirtybuffers, lodirtybuffers, hidirtybuffers; 101 static int numfreebuffers, lofreebuffers, hifreebuffers; 102 static int getnewbufcalls; 103 static int getnewbufrestarts; 104 105 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, 106 &numdirtybuffers, 0, ""); 107 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, 108 &lodirtybuffers, 0, ""); 109 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, 110 &hidirtybuffers, 0, ""); 111 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, 112 &numfreebuffers, 0, ""); 113 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, 114 &lofreebuffers, 0, ""); 115 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, 116 &hifreebuffers, 0, ""); 117 SYSCTL_INT(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, 118 &runningbufspace, 0, ""); 119 SYSCTL_INT(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, 120 &lorunningspace, 0, ""); 121 SYSCTL_INT(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, 122 &hirunningspace, 0, ""); 123 SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, 124 &maxbufspace, 0, ""); 125 SYSCTL_INT(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, 126 &hibufspace, 0, ""); 127 SYSCTL_INT(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, 128 &lobufspace, 0, ""); 129 SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, 130 &bufspace, 0, ""); 131 SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, 132 &maxbufmallocspace, 0, ""); 133 SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, 134 &bufmallocspace, 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 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, 142 &bufdefragcnt, 0, ""); 143 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, 144 &buffreekvacnt, 0, ""); 145 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, 146 &bufreusecnt, 0, ""); 147 148 /* 149 * Disable background writes for now. There appear to be races in the 150 * flags tests and locking operations as well as races in the completion 151 * code modifying the original bp (origbp) without holding a lock, assuming 152 * splbio protection when there might not be splbio protection. 153 */ 154 static int dobkgrdwrite = 0; 155 SYSCTL_INT(_debug, OID_AUTO, dobkgrdwrite, CTLFLAG_RW, &dobkgrdwrite, 0, 156 "Do background writes (honoring the BV_BKGRDWRITE flag)?"); 157 158 static int bufhashmask; 159 static int bufhashshift; 160 static LIST_HEAD(bufhashhdr, buf) *bufhashtbl, invalhash; 161 struct bqueues bufqueues[BUFFER_QUEUES] = { { 0 } }; 162 char *buf_wmesg = BUF_WMESG; 163 164 extern int vm_swap_size; 165 166 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 167 #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */ 168 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ 169 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 170 171 /* 172 * Buffer hash table code. Note that the logical block scans linearly, which 173 * gives us some L1 cache locality. 174 */ 175 176 static __inline 177 struct bufhashhdr * 178 bufhash(struct vnode *vnp, daddr_t bn) 179 { 180 u_int64_t hashkey64; 181 int hashkey; 182 183 /* 184 * A variation on the Fibonacci hash that Knuth credits to 185 * R. W. Floyd, see Knuth's _Art of Computer Programming, 186 * Volume 3 / Sorting and Searching_ 187 * 188 * We reduce the argument to 32 bits before doing the hash to 189 * avoid the need for a slow 64x64 multiply on 32 bit platforms. 190 * 191 * sizeof(struct vnode) is 168 on i386, so toss some of the lower 192 * bits of the vnode address to reduce the key range, which 193 * improves the distribution of keys across buckets. 194 * 195 * The file system cylinder group blocks are very heavily 196 * used. They are located at invervals of fbg, which is 197 * on the order of 89 to 94 * 2^10, depending on other 198 * filesystem parameters, for a 16k block size. Smaller block 199 * sizes will reduce fpg approximately proportionally. This 200 * will cause the cylinder group index to be hashed using the 201 * lower bits of the hash multiplier, which will not distribute 202 * the keys as uniformly in a classic Fibonacci hash where a 203 * relatively small number of the upper bits of the result 204 * are used. Using 2^16 as a close-enough approximation to 205 * fpg, split the hash multiplier in half, with the upper 16 206 * bits being the inverse of the golden ratio, and the lower 207 * 16 bits being a fraction between 1/3 and 3/7 (closer to 208 * 3/7 in this case), that gives good experimental results. 209 */ 210 hashkey64 = ((u_int64_t)(uintptr_t)vnp >> 3) + (u_int64_t)bn; 211 hashkey = (((u_int32_t)(hashkey64 + (hashkey64 >> 32)) * 0x9E376DB1u) >> 212 bufhashshift) & bufhashmask; 213 return(&bufhashtbl[hashkey]); 214 } 215 216 /* 217 * numdirtywakeup: 218 * 219 * If someone is blocked due to there being too many dirty buffers, 220 * and numdirtybuffers is now reasonable, wake them up. 221 */ 222 223 static __inline void 224 numdirtywakeup(int level) 225 { 226 if (numdirtybuffers <= level) { 227 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) { 228 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH; 229 wakeup(&needsbuffer); 230 } 231 } 232 } 233 234 /* 235 * bufspacewakeup: 236 * 237 * Called when buffer space is potentially available for recovery. 238 * getnewbuf() will block on this flag when it is unable to free 239 * sufficient buffer space. Buffer space becomes recoverable when 240 * bp's get placed back in the queues. 241 */ 242 243 static __inline void 244 bufspacewakeup(void) 245 { 246 /* 247 * If someone is waiting for BUF space, wake them up. Even 248 * though we haven't freed the kva space yet, the waiting 249 * process will be able to now. 250 */ 251 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) { 252 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE; 253 wakeup(&needsbuffer); 254 } 255 } 256 257 /* 258 * runningbufwakeup() - in-progress I/O accounting. 259 * 260 */ 261 static __inline void 262 runningbufwakeup(struct buf *bp) 263 { 264 if (bp->b_runningbufspace) { 265 runningbufspace -= bp->b_runningbufspace; 266 bp->b_runningbufspace = 0; 267 if (runningbufreq && runningbufspace <= lorunningspace) { 268 runningbufreq = 0; 269 wakeup(&runningbufreq); 270 } 271 } 272 } 273 274 /* 275 * bufcountwakeup: 276 * 277 * Called when a buffer has been added to one of the free queues to 278 * account for the buffer and to wakeup anyone waiting for free buffers. 279 * This typically occurs when large amounts of metadata are being handled 280 * by the buffer cache ( else buffer space runs out first, usually ). 281 */ 282 283 static __inline void 284 bufcountwakeup(void) 285 { 286 ++numfreebuffers; 287 if (needsbuffer) { 288 needsbuffer &= ~VFS_BIO_NEED_ANY; 289 if (numfreebuffers >= hifreebuffers) 290 needsbuffer &= ~VFS_BIO_NEED_FREE; 291 wakeup(&needsbuffer); 292 } 293 } 294 295 /* 296 * waitrunningbufspace() 297 * 298 * runningbufspace is a measure of the amount of I/O currently 299 * running. This routine is used in async-write situations to 300 * prevent creating huge backups of pending writes to a device. 301 * Only asynchronous writes are governed by this function. 302 * 303 * Reads will adjust runningbufspace, but will not block based on it. 304 * The read load has a side effect of reducing the allowed write load. 305 * 306 * This does NOT turn an async write into a sync write. It waits 307 * for earlier writes to complete and generally returns before the 308 * caller's write has reached the device. 309 */ 310 static __inline void 311 waitrunningbufspace(void) 312 { 313 while (runningbufspace > hirunningspace) { 314 int s; 315 316 s = splbio(); /* fix race against interrupt/biodone() */ 317 ++runningbufreq; 318 tsleep(&runningbufreq, 0, "wdrain", 0); 319 splx(s); 320 } 321 } 322 323 /* 324 * vfs_buf_test_cache: 325 * 326 * Called when a buffer is extended. This function clears the B_CACHE 327 * bit if the newly extended portion of the buffer does not contain 328 * valid data. 329 */ 330 static __inline__ 331 void 332 vfs_buf_test_cache(struct buf *bp, 333 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 334 vm_page_t m) 335 { 336 if (bp->b_flags & B_CACHE) { 337 int base = (foff + off) & PAGE_MASK; 338 if (vm_page_is_valid(m, base, size) == 0) 339 bp->b_flags &= ~B_CACHE; 340 } 341 } 342 343 static __inline__ 344 void 345 bd_wakeup(int dirtybuflevel) 346 { 347 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) { 348 bd_request = 1; 349 wakeup(&bd_request); 350 } 351 } 352 353 /* 354 * bd_speedup - speedup the buffer cache flushing code 355 */ 356 357 static __inline__ 358 void 359 bd_speedup(void) 360 { 361 bd_wakeup(1); 362 } 363 364 /* 365 * Initialize buffer headers and related structures. 366 */ 367 368 caddr_t 369 bufhashinit(caddr_t vaddr) 370 { 371 /* first, make a null hash table */ 372 bufhashshift = 29; 373 for (bufhashmask = 8; bufhashmask < nbuf / 4; bufhashmask <<= 1) 374 bufhashshift--; 375 bufhashtbl = (void *)vaddr; 376 vaddr = vaddr + sizeof(*bufhashtbl) * bufhashmask; 377 --bufhashmask; 378 return(vaddr); 379 } 380 381 void 382 bufinit(void) 383 { 384 struct buf *bp; 385 int i; 386 387 TAILQ_INIT(&bswlist); 388 LIST_INIT(&invalhash); 389 lwkt_token_init(&buftimetoken); 390 391 for (i = 0; i <= bufhashmask; i++) 392 LIST_INIT(&bufhashtbl[i]); 393 394 /* next, make a null set of free lists */ 395 for (i = 0; i < BUFFER_QUEUES; i++) 396 TAILQ_INIT(&bufqueues[i]); 397 398 /* finally, initialize each buffer header and stick on empty q */ 399 for (i = 0; i < nbuf; i++) { 400 bp = &buf[i]; 401 bzero(bp, sizeof *bp); 402 bp->b_flags = B_INVAL; /* we're just an empty header */ 403 bp->b_dev = NODEV; 404 bp->b_qindex = QUEUE_EMPTY; 405 bp->b_xflags = 0; 406 xio_init(&bp->b_xio); 407 LIST_INIT(&bp->b_dep); 408 BUF_LOCKINIT(bp); 409 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 410 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 411 } 412 413 /* 414 * maxbufspace is the absolute maximum amount of buffer space we are 415 * allowed to reserve in KVM and in real terms. The absolute maximum 416 * is nominally used by buf_daemon. hibufspace is the nominal maximum 417 * used by most other processes. The differential is required to 418 * ensure that buf_daemon is able to run when other processes might 419 * be blocked waiting for buffer space. 420 * 421 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 422 * this may result in KVM fragmentation which is not handled optimally 423 * by the system. 424 */ 425 maxbufspace = nbuf * BKVASIZE; 426 hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 427 lobufspace = hibufspace - MAXBSIZE; 428 429 lorunningspace = 512 * 1024; 430 hirunningspace = 1024 * 1024; 431 432 /* 433 * Limit the amount of malloc memory since it is wired permanently into 434 * the kernel space. Even though this is accounted for in the buffer 435 * allocation, we don't want the malloced region to grow uncontrolled. 436 * The malloc scheme improves memory utilization significantly on average 437 * (small) directories. 438 */ 439 maxbufmallocspace = hibufspace / 20; 440 441 /* 442 * Reduce the chance of a deadlock occuring by limiting the number 443 * of delayed-write dirty buffers we allow to stack up. 444 */ 445 hidirtybuffers = nbuf / 4 + 20; 446 numdirtybuffers = 0; 447 /* 448 * To support extreme low-memory systems, make sure hidirtybuffers cannot 449 * eat up all available buffer space. This occurs when our minimum cannot 450 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 451 * BKVASIZE'd (8K) buffers. 452 */ 453 while (hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 454 hidirtybuffers >>= 1; 455 } 456 lodirtybuffers = hidirtybuffers / 2; 457 458 /* 459 * Try to keep the number of free buffers in the specified range, 460 * and give special processes (e.g. like buf_daemon) access to an 461 * emergency reserve. 462 */ 463 lofreebuffers = nbuf / 18 + 5; 464 hifreebuffers = 2 * lofreebuffers; 465 numfreebuffers = nbuf; 466 467 /* 468 * Maximum number of async ops initiated per buf_daemon loop. This is 469 * somewhat of a hack at the moment, we really need to limit ourselves 470 * based on the number of bytes of I/O in-transit that were initiated 471 * from buf_daemon. 472 */ 473 474 bogus_offset = kmem_alloc_pageable(kernel_map, PAGE_SIZE); 475 bogus_page = vm_page_alloc(kernel_object, 476 ((bogus_offset - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 477 VM_ALLOC_NORMAL); 478 vmstats.v_wire_count++; 479 480 } 481 482 /* 483 * bfreekva() - free the kva allocation for a buffer. 484 * 485 * Must be called at splbio() or higher as this is the only locking for 486 * buffer_map. 487 * 488 * Since this call frees up buffer space, we call bufspacewakeup(). 489 */ 490 static void 491 bfreekva(struct buf * bp) 492 { 493 int count; 494 495 if (bp->b_kvasize) { 496 ++buffreekvacnt; 497 count = vm_map_entry_reserve(MAP_RESERVE_COUNT); 498 vm_map_lock(buffer_map); 499 bufspace -= bp->b_kvasize; 500 vm_map_delete(buffer_map, 501 (vm_offset_t) bp->b_kvabase, 502 (vm_offset_t) bp->b_kvabase + bp->b_kvasize, 503 &count 504 ); 505 vm_map_unlock(buffer_map); 506 vm_map_entry_release(count); 507 bp->b_kvasize = 0; 508 bufspacewakeup(); 509 } 510 } 511 512 /* 513 * bremfree: 514 * 515 * Remove the buffer from the appropriate free list. 516 */ 517 void 518 bremfree(struct buf * bp) 519 { 520 int s = splbio(); 521 int old_qindex = bp->b_qindex; 522 523 if (bp->b_qindex != QUEUE_NONE) { 524 KASSERT(BUF_REFCNT(bp) == 1, ("bremfree: bp %p not locked",bp)); 525 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 526 bp->b_qindex = QUEUE_NONE; 527 } else { 528 if (BUF_REFCNT(bp) <= 1) 529 panic("bremfree: removing a buffer not on a queue"); 530 } 531 532 /* 533 * Fixup numfreebuffers count. If the buffer is invalid or not 534 * delayed-write, and it was on the EMPTY, LRU, or AGE queues, 535 * the buffer was free and we must decrement numfreebuffers. 536 */ 537 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { 538 switch(old_qindex) { 539 case QUEUE_DIRTY: 540 case QUEUE_CLEAN: 541 case QUEUE_EMPTY: 542 case QUEUE_EMPTYKVA: 543 --numfreebuffers; 544 break; 545 default: 546 break; 547 } 548 } 549 splx(s); 550 } 551 552 553 /* 554 * Get a buffer with the specified data. Look in the cache first. We 555 * must clear B_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 556 * is set, the buffer is valid and we do not have to do anything ( see 557 * getblk() ). 558 */ 559 int 560 bread(struct vnode * vp, daddr_t blkno, int size, struct buf ** bpp) 561 { 562 struct buf *bp; 563 564 bp = getblk(vp, blkno, size, 0, 0); 565 *bpp = bp; 566 567 /* if not found in cache, do some I/O */ 568 if ((bp->b_flags & B_CACHE) == 0) { 569 KASSERT(!(bp->b_flags & B_ASYNC), ("bread: illegal async bp %p", bp)); 570 bp->b_flags |= B_READ; 571 bp->b_flags &= ~(B_ERROR | B_INVAL); 572 vfs_busy_pages(bp, 0); 573 VOP_STRATEGY(vp, bp); 574 return (biowait(bp)); 575 } 576 return (0); 577 } 578 579 /* 580 * Operates like bread, but also starts asynchronous I/O on 581 * read-ahead blocks. We must clear B_ERROR and B_INVAL prior 582 * to initiating I/O . If B_CACHE is set, the buffer is valid 583 * and we do not have to do anything. 584 */ 585 int 586 breadn(struct vnode * vp, daddr_t blkno, int size, daddr_t * rablkno, 587 int *rabsize, int cnt, struct buf ** bpp) 588 { 589 struct buf *bp, *rabp; 590 int i; 591 int rv = 0, readwait = 0; 592 593 *bpp = bp = getblk(vp, blkno, size, 0, 0); 594 595 /* if not found in cache, do some I/O */ 596 if ((bp->b_flags & B_CACHE) == 0) { 597 bp->b_flags |= B_READ; 598 bp->b_flags &= ~(B_ERROR | B_INVAL); 599 vfs_busy_pages(bp, 0); 600 VOP_STRATEGY(vp, bp); 601 ++readwait; 602 } 603 604 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 605 if (inmem(vp, *rablkno)) 606 continue; 607 rabp = getblk(vp, *rablkno, *rabsize, 0, 0); 608 609 if ((rabp->b_flags & B_CACHE) == 0) { 610 rabp->b_flags |= B_READ | B_ASYNC; 611 rabp->b_flags &= ~(B_ERROR | B_INVAL); 612 vfs_busy_pages(rabp, 0); 613 BUF_KERNPROC(rabp); 614 VOP_STRATEGY(vp, rabp); 615 } else { 616 brelse(rabp); 617 } 618 } 619 620 if (readwait) { 621 rv = biowait(bp); 622 } 623 return (rv); 624 } 625 626 /* 627 * Write, release buffer on completion. (Done by iodone 628 * if async). Do not bother writing anything if the buffer 629 * is invalid. 630 * 631 * Note that we set B_CACHE here, indicating that buffer is 632 * fully valid and thus cacheable. This is true even of NFS 633 * now so we set it generally. This could be set either here 634 * or in biodone() since the I/O is synchronous. We put it 635 * here. 636 */ 637 int 638 bwrite(struct buf * bp) 639 { 640 int oldflags, s; 641 struct buf *newbp; 642 643 if (bp->b_flags & B_INVAL) { 644 brelse(bp); 645 return (0); 646 } 647 648 oldflags = bp->b_flags; 649 650 if (BUF_REFCNT(bp) == 0) 651 panic("bwrite: buffer is not busy???"); 652 s = splbio(); 653 /* 654 * If a background write is already in progress, delay 655 * writing this block if it is asynchronous. Otherwise 656 * wait for the background write to complete. 657 */ 658 if (bp->b_xflags & BX_BKGRDINPROG) { 659 if (bp->b_flags & B_ASYNC) { 660 splx(s); 661 bdwrite(bp); 662 return (0); 663 } 664 bp->b_xflags |= BX_BKGRDWAIT; 665 tsleep(&bp->b_xflags, 0, "biord", 0); 666 if (bp->b_xflags & BX_BKGRDINPROG) 667 panic("bwrite: still writing"); 668 } 669 670 /* Mark the buffer clean */ 671 bundirty(bp); 672 673 /* 674 * If this buffer is marked for background writing and we 675 * do not have to wait for it, make a copy and write the 676 * copy so as to leave this buffer ready for further use. 677 * 678 * This optimization eats a lot of memory. If we have a page 679 * or buffer shortfull we can't do it. 680 */ 681 if (dobkgrdwrite && 682 (bp->b_xflags & BX_BKGRDWRITE) && 683 (bp->b_flags & B_ASYNC) && 684 !vm_page_count_severe() && 685 !buf_dirty_count_severe()) { 686 if (bp->b_flags & B_CALL) 687 panic("bwrite: need chained iodone"); 688 689 /* get a new block */ 690 newbp = geteblk(bp->b_bufsize); 691 692 /* set it to be identical to the old block */ 693 memcpy(newbp->b_data, bp->b_data, bp->b_bufsize); 694 bgetvp(bp->b_vp, newbp); 695 newbp->b_lblkno = bp->b_lblkno; 696 newbp->b_blkno = bp->b_blkno; 697 newbp->b_offset = bp->b_offset; 698 newbp->b_iodone = vfs_backgroundwritedone; 699 newbp->b_flags |= B_ASYNC | B_CALL; 700 newbp->b_flags &= ~B_INVAL; 701 702 /* move over the dependencies */ 703 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_movedeps) 704 (*bioops.io_movedeps)(bp, newbp); 705 706 /* 707 * Initiate write on the copy, release the original to 708 * the B_LOCKED queue so that it cannot go away until 709 * the background write completes. If not locked it could go 710 * away and then be reconstituted while it was being written. 711 * If the reconstituted buffer were written, we could end up 712 * with two background copies being written at the same time. 713 */ 714 bp->b_xflags |= BX_BKGRDINPROG; 715 bp->b_flags |= B_LOCKED; 716 bqrelse(bp); 717 bp = newbp; 718 } 719 720 bp->b_flags &= ~(B_READ | B_DONE | B_ERROR); 721 bp->b_flags |= B_WRITEINPROG | B_CACHE; 722 723 bp->b_vp->v_numoutput++; 724 vfs_busy_pages(bp, 1); 725 726 /* 727 * Normal bwrites pipeline writes 728 */ 729 bp->b_runningbufspace = bp->b_bufsize; 730 runningbufspace += bp->b_runningbufspace; 731 732 splx(s); 733 if (oldflags & B_ASYNC) 734 BUF_KERNPROC(bp); 735 VOP_STRATEGY(bp->b_vp, bp); 736 737 if ((oldflags & B_ASYNC) == 0) { 738 int rtval = biowait(bp); 739 brelse(bp); 740 return (rtval); 741 } else if ((oldflags & B_NOWDRAIN) == 0) { 742 /* 743 * don't allow the async write to saturate the I/O 744 * system. Deadlocks can occur only if a device strategy 745 * routine (like in VN) turns around and issues another 746 * high-level write, in which case B_NOWDRAIN is expected 747 * to be set. Otherwise we will not deadlock here because 748 * we are blocking waiting for I/O that is already in-progress 749 * to complete. 750 */ 751 waitrunningbufspace(); 752 } 753 754 return (0); 755 } 756 757 /* 758 * Complete a background write started from bwrite. 759 */ 760 static void 761 vfs_backgroundwritedone(struct buf *bp) 762 { 763 struct buf *origbp; 764 765 /* 766 * Find the original buffer that we are writing. 767 */ 768 if ((origbp = gbincore(bp->b_vp, bp->b_lblkno)) == NULL) 769 panic("backgroundwritedone: lost buffer"); 770 /* 771 * Process dependencies then return any unfinished ones. 772 */ 773 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_complete) 774 (*bioops.io_complete)(bp); 775 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_movedeps) 776 (*bioops.io_movedeps)(bp, origbp); 777 /* 778 * Clear the BX_BKGRDINPROG flag in the original buffer 779 * and awaken it if it is waiting for the write to complete. 780 * If BX_BKGRDINPROG is not set in the original buffer it must 781 * have been released and re-instantiated - which is not legal. 782 */ 783 KASSERT((origbp->b_xflags & BX_BKGRDINPROG), ("backgroundwritedone: lost buffer2")); 784 origbp->b_xflags &= ~BX_BKGRDINPROG; 785 if (origbp->b_xflags & BX_BKGRDWAIT) { 786 origbp->b_xflags &= ~BX_BKGRDWAIT; 787 wakeup(&origbp->b_xflags); 788 } 789 /* 790 * Clear the B_LOCKED flag and remove it from the locked 791 * queue if it currently resides there. 792 */ 793 origbp->b_flags &= ~B_LOCKED; 794 if (BUF_LOCK(origbp, LK_EXCLUSIVE | LK_NOWAIT) == 0) { 795 bremfree(origbp); 796 bqrelse(origbp); 797 } 798 /* 799 * This buffer is marked B_NOCACHE, so when it is released 800 * by biodone, it will be tossed. We mark it with B_READ 801 * to avoid biodone doing a second vwakeup. 802 */ 803 bp->b_flags |= B_NOCACHE | B_READ; 804 bp->b_flags &= ~(B_CACHE | B_CALL | B_DONE); 805 bp->b_iodone = 0; 806 biodone(bp); 807 } 808 809 /* 810 * Delayed write. (Buffer is marked dirty). Do not bother writing 811 * anything if the buffer is marked invalid. 812 * 813 * Note that since the buffer must be completely valid, we can safely 814 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 815 * biodone() in order to prevent getblk from writing the buffer 816 * out synchronously. 817 */ 818 void 819 bdwrite(struct buf *bp) 820 { 821 if (BUF_REFCNT(bp) == 0) 822 panic("bdwrite: buffer is not busy"); 823 824 if (bp->b_flags & B_INVAL) { 825 brelse(bp); 826 return; 827 } 828 bdirty(bp); 829 830 /* 831 * Set B_CACHE, indicating that the buffer is fully valid. This is 832 * true even of NFS now. 833 */ 834 bp->b_flags |= B_CACHE; 835 836 /* 837 * This bmap keeps the system from needing to do the bmap later, 838 * perhaps when the system is attempting to do a sync. Since it 839 * is likely that the indirect block -- or whatever other datastructure 840 * that the filesystem needs is still in memory now, it is a good 841 * thing to do this. Note also, that if the pageout daemon is 842 * requesting a sync -- there might not be enough memory to do 843 * the bmap then... So, this is important to do. 844 */ 845 if (bp->b_lblkno == bp->b_blkno) { 846 VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 847 } 848 849 /* 850 * Set the *dirty* buffer range based upon the VM system dirty pages. 851 */ 852 vfs_setdirty(bp); 853 854 /* 855 * We need to do this here to satisfy the vnode_pager and the 856 * pageout daemon, so that it thinks that the pages have been 857 * "cleaned". Note that since the pages are in a delayed write 858 * buffer -- the VFS layer "will" see that the pages get written 859 * out on the next sync, or perhaps the cluster will be completed. 860 */ 861 vfs_clean_pages(bp); 862 bqrelse(bp); 863 864 /* 865 * Wakeup the buffer flushing daemon if we have a lot of dirty 866 * buffers (midpoint between our recovery point and our stall 867 * point). 868 */ 869 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 870 871 /* 872 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 873 * due to the softdep code. 874 */ 875 } 876 877 /* 878 * bdirty: 879 * 880 * Turn buffer into delayed write request. We must clear B_READ and 881 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 882 * itself to properly update it in the dirty/clean lists. We mark it 883 * B_DONE to ensure that any asynchronization of the buffer properly 884 * clears B_DONE ( else a panic will occur later ). 885 * 886 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 887 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 888 * should only be called if the buffer is known-good. 889 * 890 * Since the buffer is not on a queue, we do not update the numfreebuffers 891 * count. 892 * 893 * Must be called at splbio(). 894 * The buffer must be on QUEUE_NONE. 895 */ 896 void 897 bdirty(struct buf *bp) 898 { 899 KASSERT(bp->b_qindex == QUEUE_NONE, ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 900 bp->b_flags &= ~(B_READ|B_RELBUF); 901 902 if ((bp->b_flags & B_DELWRI) == 0) { 903 bp->b_flags |= B_DONE | B_DELWRI; 904 reassignbuf(bp, bp->b_vp); 905 ++numdirtybuffers; 906 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 907 } 908 } 909 910 /* 911 * bundirty: 912 * 913 * Clear B_DELWRI for buffer. 914 * 915 * Since the buffer is not on a queue, we do not update the numfreebuffers 916 * count. 917 * 918 * Must be called at splbio(). 919 * The buffer must be on QUEUE_NONE. 920 */ 921 922 void 923 bundirty(struct buf *bp) 924 { 925 KASSERT(bp->b_qindex == QUEUE_NONE, ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 926 927 if (bp->b_flags & B_DELWRI) { 928 bp->b_flags &= ~B_DELWRI; 929 reassignbuf(bp, bp->b_vp); 930 --numdirtybuffers; 931 numdirtywakeup(lodirtybuffers); 932 } 933 /* 934 * Since it is now being written, we can clear its deferred write flag. 935 */ 936 bp->b_flags &= ~B_DEFERRED; 937 } 938 939 /* 940 * bawrite: 941 * 942 * Asynchronous write. Start output on a buffer, but do not wait for 943 * it to complete. The buffer is released when the output completes. 944 * 945 * bwrite() ( or the VOP routine anyway ) is responsible for handling 946 * B_INVAL buffers. Not us. 947 */ 948 void 949 bawrite(struct buf * bp) 950 { 951 bp->b_flags |= B_ASYNC; 952 (void) VOP_BWRITE(bp->b_vp, bp); 953 } 954 955 /* 956 * bowrite: 957 * 958 * Ordered write. Start output on a buffer, and flag it so that the 959 * device will write it in the order it was queued. The buffer is 960 * released when the output completes. bwrite() ( or the VOP routine 961 * anyway ) is responsible for handling B_INVAL buffers. 962 */ 963 int 964 bowrite(struct buf * bp) 965 { 966 bp->b_flags |= B_ORDERED | B_ASYNC; 967 return (VOP_BWRITE(bp->b_vp, bp)); 968 } 969 970 /* 971 * bwillwrite: 972 * 973 * Called prior to the locking of any vnodes when we are expecting to 974 * write. We do not want to starve the buffer cache with too many 975 * dirty buffers so we block here. By blocking prior to the locking 976 * of any vnodes we attempt to avoid the situation where a locked vnode 977 * prevents the various system daemons from flushing related buffers. 978 */ 979 980 void 981 bwillwrite(void) 982 { 983 if (numdirtybuffers >= hidirtybuffers) { 984 int s; 985 986 s = splbio(); 987 while (numdirtybuffers >= hidirtybuffers) { 988 bd_wakeup(1); 989 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH; 990 tsleep(&needsbuffer, 0, "flswai", 0); 991 } 992 splx(s); 993 } 994 } 995 996 /* 997 * Return true if we have too many dirty buffers. 998 */ 999 int 1000 buf_dirty_count_severe(void) 1001 { 1002 return(numdirtybuffers >= hidirtybuffers); 1003 } 1004 1005 /* 1006 * brelse: 1007 * 1008 * Release a busy buffer and, if requested, free its resources. The 1009 * buffer will be stashed in the appropriate bufqueue[] allowing it 1010 * to be accessed later as a cache entity or reused for other purposes. 1011 */ 1012 void 1013 brelse(struct buf * bp) 1014 { 1015 int s; 1016 1017 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1018 1019 s = splbio(); 1020 1021 if (bp->b_flags & B_LOCKED) 1022 bp->b_flags &= ~B_ERROR; 1023 1024 if ((bp->b_flags & (B_READ | B_ERROR | B_INVAL)) == B_ERROR) { 1025 /* 1026 * Failed write, redirty. Must clear B_ERROR to prevent 1027 * pages from being scrapped. If B_INVAL is set then 1028 * this case is not run and the next case is run to 1029 * destroy the buffer. B_INVAL can occur if the buffer 1030 * is outside the range supported by the underlying device. 1031 */ 1032 bp->b_flags &= ~B_ERROR; 1033 bdirty(bp); 1034 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR | B_FREEBUF)) || 1035 (bp->b_bufsize <= 0)) { 1036 /* 1037 * Either a failed I/O or we were asked to free or not 1038 * cache the buffer. 1039 */ 1040 bp->b_flags |= B_INVAL; 1041 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_deallocate) 1042 (*bioops.io_deallocate)(bp); 1043 if (bp->b_flags & B_DELWRI) { 1044 --numdirtybuffers; 1045 numdirtywakeup(lodirtybuffers); 1046 } 1047 bp->b_flags &= ~(B_DELWRI | B_CACHE | B_FREEBUF); 1048 if ((bp->b_flags & B_VMIO) == 0) { 1049 if (bp->b_bufsize) 1050 allocbuf(bp, 0); 1051 if (bp->b_vp) 1052 brelvp(bp); 1053 } 1054 } 1055 1056 /* 1057 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1058 * is called with B_DELWRI set, the underlying pages may wind up 1059 * getting freed causing a previous write (bdwrite()) to get 'lost' 1060 * because pages associated with a B_DELWRI bp are marked clean. 1061 * 1062 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1063 * if B_DELWRI is set. 1064 * 1065 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1066 * on pages to return pages to the VM page queues. 1067 */ 1068 if (bp->b_flags & B_DELWRI) 1069 bp->b_flags &= ~B_RELBUF; 1070 else if (vm_page_count_severe() && !(bp->b_xflags & BX_BKGRDINPROG)) 1071 bp->b_flags |= B_RELBUF; 1072 1073 /* 1074 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1075 * constituted, not even NFS buffers now. Two flags effect this. If 1076 * B_INVAL, the struct buf is invalidated but the VM object is kept 1077 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1078 * 1079 * If B_ERROR or B_NOCACHE is set, pages in the VM object will be 1080 * invalidated. B_ERROR cannot be set for a failed write unless the 1081 * buffer is also B_INVAL because it hits the re-dirtying code above. 1082 * 1083 * Normally we can do this whether a buffer is B_DELWRI or not. If 1084 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1085 * the commit state and we cannot afford to lose the buffer. If the 1086 * buffer has a background write in progress, we need to keep it 1087 * around to prevent it from being reconstituted and starting a second 1088 * background write. 1089 */ 1090 if ((bp->b_flags & B_VMIO) 1091 && !(bp->b_vp->v_tag == VT_NFS && 1092 !vn_isdisk(bp->b_vp, NULL) && 1093 (bp->b_flags & B_DELWRI)) 1094 ) { 1095 1096 int i, j, resid; 1097 vm_page_t m; 1098 off_t foff; 1099 vm_pindex_t poff; 1100 vm_object_t obj; 1101 struct vnode *vp; 1102 1103 vp = bp->b_vp; 1104 1105 /* 1106 * Get the base offset and length of the buffer. Note that 1107 * in the VMIO case if the buffer block size is not 1108 * page-aligned then b_data pointer may not be page-aligned. 1109 * But our b_xio.xio_pages array *IS* page aligned. 1110 * 1111 * block sizes less then DEV_BSIZE (usually 512) are not 1112 * supported due to the page granularity bits (m->valid, 1113 * m->dirty, etc...). 1114 * 1115 * See man buf(9) for more information 1116 */ 1117 1118 resid = bp->b_bufsize; 1119 foff = bp->b_offset; 1120 1121 for (i = 0; i < bp->b_xio.xio_npages; i++) { 1122 m = bp->b_xio.xio_pages[i]; 1123 vm_page_flag_clear(m, PG_ZERO); 1124 /* 1125 * If we hit a bogus page, fixup *all* of them 1126 * now. Note that we left these pages wired 1127 * when we removed them so they had better exist, 1128 * and they cannot be ripped out from under us so 1129 * no splvm() protection is necessary. 1130 */ 1131 if (m == bogus_page) { 1132 VOP_GETVOBJECT(vp, &obj); 1133 poff = OFF_TO_IDX(bp->b_offset); 1134 1135 for (j = i; j < bp->b_xio.xio_npages; j++) { 1136 vm_page_t mtmp; 1137 1138 mtmp = bp->b_xio.xio_pages[j]; 1139 if (mtmp == bogus_page) { 1140 mtmp = vm_page_lookup(obj, poff + j); 1141 if (!mtmp) { 1142 panic("brelse: page missing"); 1143 } 1144 bp->b_xio.xio_pages[j] = mtmp; 1145 } 1146 } 1147 1148 if ((bp->b_flags & B_INVAL) == 0) { 1149 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 1150 bp->b_xio.xio_pages, bp->b_xio.xio_npages); 1151 } 1152 m = bp->b_xio.xio_pages[i]; 1153 } 1154 1155 /* 1156 * Invalidate the backing store if B_NOCACHE is set 1157 * (e.g. used with vinvalbuf()). If this is NFS 1158 * we impose a requirement that the block size be 1159 * a multiple of PAGE_SIZE and create a temporary 1160 * hack to basically invalidate the whole page. The 1161 * problem is that NFS uses really odd buffer sizes 1162 * especially when tracking piecemeal writes and 1163 * it also vinvalbuf()'s a lot, which would result 1164 * in only partial page validation and invalidation 1165 * here. If the file page is mmap()'d, however, 1166 * all the valid bits get set so after we invalidate 1167 * here we would end up with weird m->valid values 1168 * like 0xfc. nfs_getpages() can't handle this so 1169 * we clear all the valid bits for the NFS case 1170 * instead of just some of them. 1171 * 1172 * The real bug is the VM system having to set m->valid 1173 * to VM_PAGE_BITS_ALL for faulted-in pages, which 1174 * itself is an artifact of the whole 512-byte 1175 * granular mess that exists to support odd block 1176 * sizes and UFS meta-data block sizes (e.g. 6144). 1177 * A complete rewrite is required. 1178 */ 1179 if (bp->b_flags & (B_NOCACHE|B_ERROR)) { 1180 int poffset = foff & PAGE_MASK; 1181 int presid; 1182 1183 presid = PAGE_SIZE - poffset; 1184 if (bp->b_vp->v_tag == VT_NFS && 1185 bp->b_vp->v_type == VREG) { 1186 ; /* entire page */ 1187 } else if (presid > resid) { 1188 presid = resid; 1189 } 1190 KASSERT(presid >= 0, ("brelse: extra page")); 1191 vm_page_set_invalid(m, poffset, presid); 1192 } 1193 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1194 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1195 } 1196 1197 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1198 vfs_vmio_release(bp); 1199 1200 } else if (bp->b_flags & B_VMIO) { 1201 1202 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1203 vfs_vmio_release(bp); 1204 1205 } 1206 1207 if (bp->b_qindex != QUEUE_NONE) 1208 panic("brelse: free buffer onto another queue???"); 1209 if (BUF_REFCNT(bp) > 1) { 1210 /* Temporary panic to verify exclusive locking */ 1211 /* This panic goes away when we allow shared refs */ 1212 panic("brelse: multiple refs"); 1213 /* do not release to free list */ 1214 BUF_UNLOCK(bp); 1215 splx(s); 1216 return; 1217 } 1218 1219 /* enqueue */ 1220 1221 /* buffers with no memory */ 1222 if (bp->b_bufsize == 0) { 1223 bp->b_flags |= B_INVAL; 1224 bp->b_xflags &= ~BX_BKGRDWRITE; 1225 if (bp->b_xflags & BX_BKGRDINPROG) 1226 panic("losing buffer 1"); 1227 if (bp->b_kvasize) { 1228 bp->b_qindex = QUEUE_EMPTYKVA; 1229 } else { 1230 bp->b_qindex = QUEUE_EMPTY; 1231 } 1232 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1233 LIST_REMOVE(bp, b_hash); 1234 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1235 bp->b_dev = NODEV; 1236 /* buffers with junk contents */ 1237 } else if (bp->b_flags & (B_ERROR | B_INVAL | B_NOCACHE | B_RELBUF)) { 1238 bp->b_flags |= B_INVAL; 1239 bp->b_xflags &= ~BX_BKGRDWRITE; 1240 if (bp->b_xflags & BX_BKGRDINPROG) 1241 panic("losing buffer 2"); 1242 bp->b_qindex = QUEUE_CLEAN; 1243 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1244 LIST_REMOVE(bp, b_hash); 1245 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1246 bp->b_dev = NODEV; 1247 1248 /* buffers that are locked */ 1249 } else if (bp->b_flags & B_LOCKED) { 1250 bp->b_qindex = QUEUE_LOCKED; 1251 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LOCKED], bp, b_freelist); 1252 1253 /* remaining buffers */ 1254 } else { 1255 switch(bp->b_flags & (B_DELWRI|B_AGE)) { 1256 case B_DELWRI | B_AGE: 1257 bp->b_qindex = QUEUE_DIRTY; 1258 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_DIRTY], bp, b_freelist); 1259 break; 1260 case B_DELWRI: 1261 bp->b_qindex = QUEUE_DIRTY; 1262 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist); 1263 break; 1264 case B_AGE: 1265 bp->b_qindex = QUEUE_CLEAN; 1266 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1267 break; 1268 default: 1269 bp->b_qindex = QUEUE_CLEAN; 1270 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1271 break; 1272 } 1273 } 1274 1275 /* 1276 * If B_INVAL, clear B_DELWRI. We've already placed the buffer 1277 * on the correct queue. 1278 */ 1279 if ((bp->b_flags & (B_INVAL|B_DELWRI)) == (B_INVAL|B_DELWRI)) 1280 bundirty(bp); 1281 1282 /* 1283 * Fixup numfreebuffers count. The bp is on an appropriate queue 1284 * unless locked. We then bump numfreebuffers if it is not B_DELWRI. 1285 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1286 * if B_INVAL is set ). 1287 */ 1288 1289 if ((bp->b_flags & B_LOCKED) == 0 && !(bp->b_flags & B_DELWRI)) 1290 bufcountwakeup(); 1291 1292 /* 1293 * Something we can maybe free or reuse 1294 */ 1295 if (bp->b_bufsize || bp->b_kvasize) 1296 bufspacewakeup(); 1297 1298 /* unlock */ 1299 BUF_UNLOCK(bp); 1300 bp->b_flags &= ~(B_ORDERED | B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | 1301 B_DIRECT | B_NOWDRAIN); 1302 splx(s); 1303 } 1304 1305 /* 1306 * Release a buffer back to the appropriate queue but do not try to free 1307 * it. The buffer is expected to be used again soon. 1308 * 1309 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1310 * biodone() to requeue an async I/O on completion. It is also used when 1311 * known good buffers need to be requeued but we think we may need the data 1312 * again soon. 1313 * 1314 * XXX we should be able to leave the B_RELBUF hint set on completion. 1315 */ 1316 void 1317 bqrelse(struct buf * bp) 1318 { 1319 int s; 1320 1321 s = splbio(); 1322 1323 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1324 1325 if (bp->b_qindex != QUEUE_NONE) 1326 panic("bqrelse: free buffer onto another queue???"); 1327 if (BUF_REFCNT(bp) > 1) { 1328 /* do not release to free list */ 1329 panic("bqrelse: multiple refs"); 1330 BUF_UNLOCK(bp); 1331 splx(s); 1332 return; 1333 } 1334 if (bp->b_flags & B_LOCKED) { 1335 bp->b_flags &= ~B_ERROR; 1336 bp->b_qindex = QUEUE_LOCKED; 1337 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LOCKED], bp, b_freelist); 1338 /* buffers with stale but valid contents */ 1339 } else if (bp->b_flags & B_DELWRI) { 1340 bp->b_qindex = QUEUE_DIRTY; 1341 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist); 1342 } else if (vm_page_count_severe()) { 1343 /* 1344 * We are too low on memory, we have to try to free the 1345 * buffer (most importantly: the wired pages making up its 1346 * backing store) *now*. 1347 */ 1348 splx(s); 1349 brelse(bp); 1350 return; 1351 } else { 1352 bp->b_qindex = QUEUE_CLEAN; 1353 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1354 } 1355 1356 if ((bp->b_flags & B_LOCKED) == 0 && 1357 ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI))) { 1358 bufcountwakeup(); 1359 } 1360 1361 /* 1362 * Something we can maybe free or reuse. 1363 */ 1364 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1365 bufspacewakeup(); 1366 1367 /* unlock */ 1368 BUF_UNLOCK(bp); 1369 bp->b_flags &= ~(B_ORDERED | B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1370 splx(s); 1371 } 1372 1373 static void 1374 vfs_vmio_release(struct buf *bp) 1375 { 1376 int i, s; 1377 vm_page_t m; 1378 1379 s = splvm(); 1380 for (i = 0; i < bp->b_xio.xio_npages; i++) { 1381 m = bp->b_xio.xio_pages[i]; 1382 bp->b_xio.xio_pages[i] = NULL; 1383 /* 1384 * In order to keep page LRU ordering consistent, put 1385 * everything on the inactive queue. 1386 */ 1387 vm_page_unwire(m, 0); 1388 /* 1389 * We don't mess with busy pages, it is 1390 * the responsibility of the process that 1391 * busied the pages to deal with them. 1392 */ 1393 if ((m->flags & PG_BUSY) || (m->busy != 0)) 1394 continue; 1395 1396 if (m->wire_count == 0) { 1397 vm_page_flag_clear(m, PG_ZERO); 1398 /* 1399 * Might as well free the page if we can and it has 1400 * no valid data. We also free the page if the 1401 * buffer was used for direct I/O. 1402 */ 1403 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && m->hold_count == 0) { 1404 vm_page_busy(m); 1405 vm_page_protect(m, VM_PROT_NONE); 1406 vm_page_free(m); 1407 } else if (bp->b_flags & B_DIRECT) { 1408 vm_page_try_to_free(m); 1409 } else if (vm_page_count_severe()) { 1410 vm_page_try_to_cache(m); 1411 } 1412 } 1413 } 1414 splx(s); 1415 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_xio.xio_npages); 1416 if (bp->b_bufsize) { 1417 bufspacewakeup(); 1418 bp->b_bufsize = 0; 1419 } 1420 bp->b_xio.xio_npages = 0; 1421 bp->b_flags &= ~B_VMIO; 1422 if (bp->b_vp) 1423 brelvp(bp); 1424 } 1425 1426 /* 1427 * Check to see if a block is currently memory resident. 1428 */ 1429 struct buf * 1430 gbincore(struct vnode * vp, daddr_t blkno) 1431 { 1432 struct buf *bp; 1433 struct bufhashhdr *bh; 1434 1435 bh = bufhash(vp, blkno); 1436 1437 /* Search hash chain */ 1438 LIST_FOREACH(bp, bh, b_hash) { 1439 /* hit */ 1440 if (bp->b_vp == vp && bp->b_lblkno == blkno && 1441 (bp->b_flags & B_INVAL) == 0) { 1442 break; 1443 } 1444 } 1445 return (bp); 1446 } 1447 1448 /* 1449 * vfs_bio_awrite: 1450 * 1451 * Implement clustered async writes for clearing out B_DELWRI buffers. 1452 * This is much better then the old way of writing only one buffer at 1453 * a time. Note that we may not be presented with the buffers in the 1454 * correct order, so we search for the cluster in both directions. 1455 */ 1456 int 1457 vfs_bio_awrite(struct buf * bp) 1458 { 1459 int i; 1460 int j; 1461 daddr_t lblkno = bp->b_lblkno; 1462 struct vnode *vp = bp->b_vp; 1463 int s; 1464 int ncl; 1465 struct buf *bpa; 1466 int nwritten; 1467 int size; 1468 int maxcl; 1469 1470 s = splbio(); 1471 /* 1472 * right now we support clustered writing only to regular files. If 1473 * we find a clusterable block we could be in the middle of a cluster 1474 * rather then at the beginning. 1475 */ 1476 if ((vp->v_type == VREG) && 1477 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1478 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1479 1480 size = vp->v_mount->mnt_stat.f_iosize; 1481 maxcl = MAXPHYS / size; 1482 1483 for (i = 1; i < maxcl; i++) { 1484 if ((bpa = gbincore(vp, lblkno + i)) && 1485 BUF_REFCNT(bpa) == 0 && 1486 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == 1487 (B_DELWRI | B_CLUSTEROK)) && 1488 (bpa->b_bufsize == size)) { 1489 if ((bpa->b_blkno == bpa->b_lblkno) || 1490 (bpa->b_blkno != 1491 bp->b_blkno + ((i * size) >> DEV_BSHIFT))) 1492 break; 1493 } else { 1494 break; 1495 } 1496 } 1497 for (j = 1; i + j <= maxcl && j <= lblkno; j++) { 1498 if ((bpa = gbincore(vp, lblkno - j)) && 1499 BUF_REFCNT(bpa) == 0 && 1500 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == 1501 (B_DELWRI | B_CLUSTEROK)) && 1502 (bpa->b_bufsize == size)) { 1503 if ((bpa->b_blkno == bpa->b_lblkno) || 1504 (bpa->b_blkno != 1505 bp->b_blkno - ((j * size) >> DEV_BSHIFT))) 1506 break; 1507 } else { 1508 break; 1509 } 1510 } 1511 --j; 1512 ncl = i + j; 1513 /* 1514 * this is a possible cluster write 1515 */ 1516 if (ncl != 1) { 1517 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl); 1518 splx(s); 1519 return nwritten; 1520 } 1521 } 1522 1523 BUF_LOCK(bp, LK_EXCLUSIVE); 1524 bremfree(bp); 1525 bp->b_flags |= B_ASYNC; 1526 1527 splx(s); 1528 /* 1529 * default (old) behavior, writing out only one block 1530 * 1531 * XXX returns b_bufsize instead of b_bcount for nwritten? 1532 */ 1533 nwritten = bp->b_bufsize; 1534 (void) VOP_BWRITE(bp->b_vp, bp); 1535 1536 return nwritten; 1537 } 1538 1539 /* 1540 * getnewbuf: 1541 * 1542 * Find and initialize a new buffer header, freeing up existing buffers 1543 * in the bufqueues as necessary. The new buffer is returned locked. 1544 * 1545 * Important: B_INVAL is not set. If the caller wishes to throw the 1546 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1547 * 1548 * We block if: 1549 * We have insufficient buffer headers 1550 * We have insufficient buffer space 1551 * buffer_map is too fragmented ( space reservation fails ) 1552 * If we have to flush dirty buffers ( but we try to avoid this ) 1553 * 1554 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1555 * Instead we ask the buf daemon to do it for us. We attempt to 1556 * avoid piecemeal wakeups of the pageout daemon. 1557 */ 1558 1559 static struct buf * 1560 getnewbuf(int slpflag, int slptimeo, int size, int maxsize) 1561 { 1562 struct buf *bp; 1563 struct buf *nbp; 1564 int defrag = 0; 1565 int nqindex; 1566 static int flushingbufs; 1567 1568 /* 1569 * We can't afford to block since we might be holding a vnode lock, 1570 * which may prevent system daemons from running. We deal with 1571 * low-memory situations by proactively returning memory and running 1572 * async I/O rather then sync I/O. 1573 */ 1574 1575 ++getnewbufcalls; 1576 --getnewbufrestarts; 1577 restart: 1578 ++getnewbufrestarts; 1579 1580 /* 1581 * Setup for scan. If we do not have enough free buffers, 1582 * we setup a degenerate case that immediately fails. Note 1583 * that if we are specially marked process, we are allowed to 1584 * dip into our reserves. 1585 * 1586 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 1587 * 1588 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 1589 * However, there are a number of cases (defragging, reusing, ...) 1590 * where we cannot backup. 1591 */ 1592 nqindex = QUEUE_EMPTYKVA; 1593 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 1594 1595 if (nbp == NULL) { 1596 /* 1597 * If no EMPTYKVA buffers and we are either 1598 * defragging or reusing, locate a CLEAN buffer 1599 * to free or reuse. If bufspace useage is low 1600 * skip this step so we can allocate a new buffer. 1601 */ 1602 if (defrag || bufspace >= lobufspace) { 1603 nqindex = QUEUE_CLEAN; 1604 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 1605 } 1606 1607 /* 1608 * If we could not find or were not allowed to reuse a 1609 * CLEAN buffer, check to see if it is ok to use an EMPTY 1610 * buffer. We can only use an EMPTY buffer if allocating 1611 * its KVA would not otherwise run us out of buffer space. 1612 */ 1613 if (nbp == NULL && defrag == 0 && 1614 bufspace + maxsize < hibufspace) { 1615 nqindex = QUEUE_EMPTY; 1616 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1617 } 1618 } 1619 1620 /* 1621 * Run scan, possibly freeing data and/or kva mappings on the fly 1622 * depending. 1623 */ 1624 1625 while ((bp = nbp) != NULL) { 1626 int qindex = nqindex; 1627 1628 /* 1629 * Calculate next bp ( we can only use it if we do not block 1630 * or do other fancy things ). 1631 */ 1632 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 1633 switch(qindex) { 1634 case QUEUE_EMPTY: 1635 nqindex = QUEUE_EMPTYKVA; 1636 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]))) 1637 break; 1638 /* fall through */ 1639 case QUEUE_EMPTYKVA: 1640 nqindex = QUEUE_CLEAN; 1641 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]))) 1642 break; 1643 /* fall through */ 1644 case QUEUE_CLEAN: 1645 /* 1646 * nbp is NULL. 1647 */ 1648 break; 1649 } 1650 } 1651 1652 /* 1653 * Sanity Checks 1654 */ 1655 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp)); 1656 1657 /* 1658 * Note: we no longer distinguish between VMIO and non-VMIO 1659 * buffers. 1660 */ 1661 1662 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); 1663 1664 /* 1665 * If we are defragging then we need a buffer with 1666 * b_kvasize != 0. XXX this situation should no longer 1667 * occur, if defrag is non-zero the buffer's b_kvasize 1668 * should also be non-zero at this point. XXX 1669 */ 1670 if (defrag && bp->b_kvasize == 0) { 1671 printf("Warning: defrag empty buffer %p\n", bp); 1672 continue; 1673 } 1674 1675 /* 1676 * Start freeing the bp. This is somewhat involved. nbp 1677 * remains valid only for QUEUE_EMPTY[KVA] bp's. 1678 */ 1679 1680 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) 1681 panic("getnewbuf: locked buf"); 1682 bremfree(bp); 1683 1684 if (qindex == QUEUE_CLEAN) { 1685 if (bp->b_flags & B_VMIO) { 1686 bp->b_flags &= ~B_ASYNC; 1687 vfs_vmio_release(bp); 1688 } 1689 if (bp->b_vp) 1690 brelvp(bp); 1691 } 1692 1693 /* 1694 * NOTE: nbp is now entirely invalid. We can only restart 1695 * the scan from this point on. 1696 * 1697 * Get the rest of the buffer freed up. b_kva* is still 1698 * valid after this operation. 1699 */ 1700 1701 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_deallocate) 1702 (*bioops.io_deallocate)(bp); 1703 if (bp->b_xflags & BX_BKGRDINPROG) 1704 panic("losing buffer 3"); 1705 LIST_REMOVE(bp, b_hash); 1706 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1707 1708 /* 1709 * spl protection not required when scrapping a buffer's 1710 * contents because it is already wired. 1711 */ 1712 if (bp->b_bufsize) 1713 allocbuf(bp, 0); 1714 1715 bp->b_flags = 0; 1716 bp->b_xflags = 0; 1717 bp->b_dev = NODEV; 1718 bp->b_vp = NULL; 1719 bp->b_blkno = bp->b_lblkno = 0; 1720 bp->b_offset = NOOFFSET; 1721 bp->b_iodone = 0; 1722 bp->b_error = 0; 1723 bp->b_resid = 0; 1724 bp->b_bcount = 0; 1725 bp->b_xio.xio_npages = 0; 1726 bp->b_dirtyoff = bp->b_dirtyend = 0; 1727 1728 LIST_INIT(&bp->b_dep); 1729 1730 /* 1731 * If we are defragging then free the buffer. 1732 */ 1733 if (defrag) { 1734 bp->b_flags |= B_INVAL; 1735 bfreekva(bp); 1736 brelse(bp); 1737 defrag = 0; 1738 goto restart; 1739 } 1740 1741 /* 1742 * If we are overcomitted then recover the buffer and its 1743 * KVM space. This occurs in rare situations when multiple 1744 * processes are blocked in getnewbuf() or allocbuf(). 1745 */ 1746 if (bufspace >= hibufspace) 1747 flushingbufs = 1; 1748 if (flushingbufs && bp->b_kvasize != 0) { 1749 bp->b_flags |= B_INVAL; 1750 bfreekva(bp); 1751 brelse(bp); 1752 goto restart; 1753 } 1754 if (bufspace < lobufspace) 1755 flushingbufs = 0; 1756 break; 1757 } 1758 1759 /* 1760 * If we exhausted our list, sleep as appropriate. We may have to 1761 * wakeup various daemons and write out some dirty buffers. 1762 * 1763 * Generally we are sleeping due to insufficient buffer space. 1764 */ 1765 1766 if (bp == NULL) { 1767 int flags; 1768 char *waitmsg; 1769 1770 if (defrag) { 1771 flags = VFS_BIO_NEED_BUFSPACE; 1772 waitmsg = "nbufkv"; 1773 } else if (bufspace >= hibufspace) { 1774 waitmsg = "nbufbs"; 1775 flags = VFS_BIO_NEED_BUFSPACE; 1776 } else { 1777 waitmsg = "newbuf"; 1778 flags = VFS_BIO_NEED_ANY; 1779 } 1780 1781 bd_speedup(); /* heeeelp */ 1782 1783 needsbuffer |= flags; 1784 while (needsbuffer & flags) { 1785 if (tsleep(&needsbuffer, slpflag, waitmsg, slptimeo)) 1786 return (NULL); 1787 } 1788 } else { 1789 /* 1790 * We finally have a valid bp. We aren't quite out of the 1791 * woods, we still have to reserve kva space. In order 1792 * to keep fragmentation sane we only allocate kva in 1793 * BKVASIZE chunks. 1794 */ 1795 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 1796 1797 if (maxsize != bp->b_kvasize) { 1798 vm_offset_t addr = 0; 1799 int count; 1800 1801 bfreekva(bp); 1802 1803 count = vm_map_entry_reserve(MAP_RESERVE_COUNT); 1804 vm_map_lock(buffer_map); 1805 1806 if (vm_map_findspace(buffer_map, 1807 vm_map_min(buffer_map), maxsize, 1808 maxsize, &addr)) { 1809 /* 1810 * Uh oh. Buffer map is to fragmented. We 1811 * must defragment the map. 1812 */ 1813 vm_map_unlock(buffer_map); 1814 vm_map_entry_release(count); 1815 ++bufdefragcnt; 1816 defrag = 1; 1817 bp->b_flags |= B_INVAL; 1818 brelse(bp); 1819 goto restart; 1820 } 1821 if (addr) { 1822 vm_map_insert(buffer_map, &count, 1823 NULL, 0, 1824 addr, addr + maxsize, 1825 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT); 1826 1827 bp->b_kvabase = (caddr_t) addr; 1828 bp->b_kvasize = maxsize; 1829 bufspace += bp->b_kvasize; 1830 ++bufreusecnt; 1831 } 1832 vm_map_unlock(buffer_map); 1833 vm_map_entry_release(count); 1834 } 1835 bp->b_data = bp->b_kvabase; 1836 } 1837 return(bp); 1838 } 1839 1840 /* 1841 * buf_daemon: 1842 * 1843 * buffer flushing daemon. Buffers are normally flushed by the 1844 * update daemon but if it cannot keep up this process starts to 1845 * take the load in an attempt to prevent getnewbuf() from blocking. 1846 */ 1847 1848 static struct thread *bufdaemonthread; 1849 1850 static struct kproc_desc buf_kp = { 1851 "bufdaemon", 1852 buf_daemon, 1853 &bufdaemonthread 1854 }; 1855 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp) 1856 1857 static void 1858 buf_daemon() 1859 { 1860 int s; 1861 1862 /* 1863 * This process needs to be suspended prior to shutdown sync. 1864 */ 1865 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc, 1866 bufdaemonthread, SHUTDOWN_PRI_LAST); 1867 1868 /* 1869 * This process is allowed to take the buffer cache to the limit 1870 */ 1871 s = splbio(); 1872 1873 for (;;) { 1874 kproc_suspend_loop(); 1875 1876 /* 1877 * Do the flush. Limit the amount of in-transit I/O we 1878 * allow to build up, otherwise we would completely saturate 1879 * the I/O system. Wakeup any waiting processes before we 1880 * normally would so they can run in parallel with our drain. 1881 */ 1882 while (numdirtybuffers > lodirtybuffers) { 1883 if (flushbufqueues() == 0) 1884 break; 1885 waitrunningbufspace(); 1886 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 1887 } 1888 1889 /* 1890 * Only clear bd_request if we have reached our low water 1891 * mark. The buf_daemon normally waits 5 seconds and 1892 * then incrementally flushes any dirty buffers that have 1893 * built up, within reason. 1894 * 1895 * If we were unable to hit our low water mark and couldn't 1896 * find any flushable buffers, we sleep half a second. 1897 * Otherwise we loop immediately. 1898 */ 1899 if (numdirtybuffers <= lodirtybuffers) { 1900 /* 1901 * We reached our low water mark, reset the 1902 * request and sleep until we are needed again. 1903 * The sleep is just so the suspend code works. 1904 */ 1905 bd_request = 0; 1906 tsleep(&bd_request, 0, "psleep", hz); 1907 } else { 1908 /* 1909 * We couldn't find any flushable dirty buffers but 1910 * still have too many dirty buffers, we 1911 * have to sleep and try again. (rare) 1912 */ 1913 tsleep(&bd_request, 0, "qsleep", hz / 2); 1914 } 1915 } 1916 } 1917 1918 /* 1919 * flushbufqueues: 1920 * 1921 * Try to flush a buffer in the dirty queue. We must be careful to 1922 * free up B_INVAL buffers instead of write them, which NFS is 1923 * particularly sensitive to. 1924 */ 1925 1926 static int 1927 flushbufqueues(void) 1928 { 1929 struct buf *bp; 1930 int r = 0; 1931 1932 bp = TAILQ_FIRST(&bufqueues[QUEUE_DIRTY]); 1933 1934 while (bp) { 1935 KASSERT((bp->b_flags & B_DELWRI), ("unexpected clean buffer %p", bp)); 1936 if ((bp->b_flags & B_DELWRI) != 0 && 1937 (bp->b_xflags & BX_BKGRDINPROG) == 0) { 1938 if (bp->b_flags & B_INVAL) { 1939 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) 1940 panic("flushbufqueues: locked buf"); 1941 bremfree(bp); 1942 brelse(bp); 1943 ++r; 1944 break; 1945 } 1946 if (LIST_FIRST(&bp->b_dep) != NULL && 1947 bioops.io_countdeps && 1948 (bp->b_flags & B_DEFERRED) == 0 && 1949 (*bioops.io_countdeps)(bp, 0)) { 1950 TAILQ_REMOVE(&bufqueues[QUEUE_DIRTY], 1951 bp, b_freelist); 1952 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], 1953 bp, b_freelist); 1954 bp->b_flags |= B_DEFERRED; 1955 bp = TAILQ_FIRST(&bufqueues[QUEUE_DIRTY]); 1956 continue; 1957 } 1958 vfs_bio_awrite(bp); 1959 ++r; 1960 break; 1961 } 1962 bp = TAILQ_NEXT(bp, b_freelist); 1963 } 1964 return (r); 1965 } 1966 1967 /* 1968 * Check to see if a block is currently memory resident. 1969 */ 1970 struct buf * 1971 incore(struct vnode * vp, daddr_t blkno) 1972 { 1973 struct buf *bp; 1974 1975 int s = splbio(); 1976 bp = gbincore(vp, blkno); 1977 splx(s); 1978 return (bp); 1979 } 1980 1981 /* 1982 * Returns true if no I/O is needed to access the associated VM object. 1983 * This is like incore except it also hunts around in the VM system for 1984 * the data. 1985 * 1986 * Note that we ignore vm_page_free() races from interrupts against our 1987 * lookup, since if the caller is not protected our return value will not 1988 * be any more valid then otherwise once we splx(). 1989 */ 1990 int 1991 inmem(struct vnode * vp, daddr_t blkno) 1992 { 1993 vm_object_t obj; 1994 vm_offset_t toff, tinc, size; 1995 vm_page_t m; 1996 vm_ooffset_t off; 1997 1998 if (incore(vp, blkno)) 1999 return 1; 2000 if (vp->v_mount == NULL) 2001 return 0; 2002 if (VOP_GETVOBJECT(vp, &obj) != 0 || (vp->v_flag & VOBJBUF) == 0) 2003 return 0; 2004 2005 size = PAGE_SIZE; 2006 if (size > vp->v_mount->mnt_stat.f_iosize) 2007 size = vp->v_mount->mnt_stat.f_iosize; 2008 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2009 2010 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2011 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2012 if (!m) 2013 return 0; 2014 tinc = size; 2015 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2016 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2017 if (vm_page_is_valid(m, 2018 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2019 return 0; 2020 } 2021 return 1; 2022 } 2023 2024 /* 2025 * vfs_setdirty: 2026 * 2027 * Sets the dirty range for a buffer based on the status of the dirty 2028 * bits in the pages comprising the buffer. 2029 * 2030 * The range is limited to the size of the buffer. 2031 * 2032 * This routine is primarily used by NFS, but is generalized for the 2033 * B_VMIO case. 2034 */ 2035 static void 2036 vfs_setdirty(struct buf *bp) 2037 { 2038 int i; 2039 vm_object_t object; 2040 2041 /* 2042 * Degenerate case - empty buffer 2043 */ 2044 2045 if (bp->b_bufsize == 0) 2046 return; 2047 2048 /* 2049 * We qualify the scan for modified pages on whether the 2050 * object has been flushed yet. The OBJ_WRITEABLE flag 2051 * is not cleared simply by protecting pages off. 2052 */ 2053 2054 if ((bp->b_flags & B_VMIO) == 0) 2055 return; 2056 2057 object = bp->b_xio.xio_pages[0]->object; 2058 2059 if ((object->flags & OBJ_WRITEABLE) && !(object->flags & OBJ_MIGHTBEDIRTY)) 2060 printf("Warning: object %p writeable but not mightbedirty\n", object); 2061 if (!(object->flags & OBJ_WRITEABLE) && (object->flags & OBJ_MIGHTBEDIRTY)) 2062 printf("Warning: object %p mightbedirty but not writeable\n", object); 2063 2064 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) { 2065 vm_offset_t boffset; 2066 vm_offset_t eoffset; 2067 2068 /* 2069 * test the pages to see if they have been modified directly 2070 * by users through the VM system. 2071 */ 2072 for (i = 0; i < bp->b_xio.xio_npages; i++) { 2073 vm_page_flag_clear(bp->b_xio.xio_pages[i], PG_ZERO); 2074 vm_page_test_dirty(bp->b_xio.xio_pages[i]); 2075 } 2076 2077 /* 2078 * Calculate the encompassing dirty range, boffset and eoffset, 2079 * (eoffset - boffset) bytes. 2080 */ 2081 2082 for (i = 0; i < bp->b_xio.xio_npages; i++) { 2083 if (bp->b_xio.xio_pages[i]->dirty) 2084 break; 2085 } 2086 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2087 2088 for (i = bp->b_xio.xio_npages - 1; i >= 0; --i) { 2089 if (bp->b_xio.xio_pages[i]->dirty) { 2090 break; 2091 } 2092 } 2093 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2094 2095 /* 2096 * Fit it to the buffer. 2097 */ 2098 2099 if (eoffset > bp->b_bcount) 2100 eoffset = bp->b_bcount; 2101 2102 /* 2103 * If we have a good dirty range, merge with the existing 2104 * dirty range. 2105 */ 2106 2107 if (boffset < eoffset) { 2108 if (bp->b_dirtyoff > boffset) 2109 bp->b_dirtyoff = boffset; 2110 if (bp->b_dirtyend < eoffset) 2111 bp->b_dirtyend = eoffset; 2112 } 2113 } 2114 } 2115 2116 /* 2117 * getblk: 2118 * 2119 * Get a block given a specified block and offset into a file/device. 2120 * The buffers B_DONE bit will be cleared on return, making it almost 2121 * ready for an I/O initiation. B_INVAL may or may not be set on 2122 * return. The caller should clear B_INVAL prior to initiating a 2123 * READ. 2124 * 2125 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2126 * an existing buffer. 2127 * 2128 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2129 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2130 * and then cleared based on the backing VM. If the previous buffer is 2131 * non-0-sized but invalid, B_CACHE will be cleared. 2132 * 2133 * If getblk() must create a new buffer, the new buffer is returned with 2134 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2135 * case it is returned with B_INVAL clear and B_CACHE set based on the 2136 * backing VM. 2137 * 2138 * getblk() also forces a VOP_BWRITE() for any B_DELWRI buffer whos 2139 * B_CACHE bit is clear. 2140 * 2141 * What this means, basically, is that the caller should use B_CACHE to 2142 * determine whether the buffer is fully valid or not and should clear 2143 * B_INVAL prior to issuing a read. If the caller intends to validate 2144 * the buffer by loading its data area with something, the caller needs 2145 * to clear B_INVAL. If the caller does this without issuing an I/O, 2146 * the caller should set B_CACHE ( as an optimization ), else the caller 2147 * should issue the I/O and biodone() will set B_CACHE if the I/O was 2148 * a write attempt or if it was a successfull read. If the caller 2149 * intends to issue a READ, the caller must clear B_INVAL and B_ERROR 2150 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 2151 */ 2152 struct buf * 2153 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo) 2154 { 2155 struct buf *bp; 2156 int s; 2157 struct bufhashhdr *bh; 2158 2159 if (size > MAXBSIZE) 2160 panic("getblk: size(%d) > MAXBSIZE(%d)", size, MAXBSIZE); 2161 2162 s = splbio(); 2163 loop: 2164 /* 2165 * Block if we are low on buffers. Certain processes are allowed 2166 * to completely exhaust the buffer cache. 2167 * 2168 * If this check ever becomes a bottleneck it may be better to 2169 * move it into the else, when gbincore() fails. At the moment 2170 * it isn't a problem. 2171 * 2172 * XXX remove, we cannot afford to block anywhere if holding a vnode 2173 * lock in low-memory situation, so take it to the max. 2174 */ 2175 if (numfreebuffers == 0) { 2176 if (!curproc) 2177 return NULL; 2178 needsbuffer |= VFS_BIO_NEED_ANY; 2179 tsleep(&needsbuffer, slpflag, "newbuf", slptimeo); 2180 } 2181 2182 if ((bp = gbincore(vp, blkno))) { 2183 /* 2184 * Buffer is in-core. If the buffer is not busy, it must 2185 * be on a queue. 2186 */ 2187 2188 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) { 2189 if (BUF_TIMELOCK(bp, LK_EXCLUSIVE | LK_SLEEPFAIL, 2190 "getblk", slpflag, slptimeo) == ENOLCK) 2191 goto loop; 2192 splx(s); 2193 return (struct buf *) NULL; 2194 } 2195 2196 /* 2197 * The buffer is locked. B_CACHE is cleared if the buffer is 2198 * invalid. Ohterwise, for a non-VMIO buffer, B_CACHE is set 2199 * and for a VMIO buffer B_CACHE is adjusted according to the 2200 * backing VM cache. 2201 */ 2202 if (bp->b_flags & B_INVAL) 2203 bp->b_flags &= ~B_CACHE; 2204 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 2205 bp->b_flags |= B_CACHE; 2206 bremfree(bp); 2207 2208 /* 2209 * check for size inconsistancies for non-VMIO case. 2210 */ 2211 2212 if (bp->b_bcount != size) { 2213 if ((bp->b_flags & B_VMIO) == 0 || 2214 (size > bp->b_kvasize)) { 2215 if (bp->b_flags & B_DELWRI) { 2216 bp->b_flags |= B_NOCACHE; 2217 VOP_BWRITE(bp->b_vp, bp); 2218 } else { 2219 if ((bp->b_flags & B_VMIO) && 2220 (LIST_FIRST(&bp->b_dep) == NULL)) { 2221 bp->b_flags |= B_RELBUF; 2222 brelse(bp); 2223 } else { 2224 bp->b_flags |= B_NOCACHE; 2225 VOP_BWRITE(bp->b_vp, bp); 2226 } 2227 } 2228 goto loop; 2229 } 2230 } 2231 2232 /* 2233 * If the size is inconsistant in the VMIO case, we can resize 2234 * the buffer. This might lead to B_CACHE getting set or 2235 * cleared. If the size has not changed, B_CACHE remains 2236 * unchanged from its previous state. 2237 */ 2238 2239 if (bp->b_bcount != size) 2240 allocbuf(bp, size); 2241 2242 KASSERT(bp->b_offset != NOOFFSET, 2243 ("getblk: no buffer offset")); 2244 2245 /* 2246 * A buffer with B_DELWRI set and B_CACHE clear must 2247 * be committed before we can return the buffer in 2248 * order to prevent the caller from issuing a read 2249 * ( due to B_CACHE not being set ) and overwriting 2250 * it. 2251 * 2252 * Most callers, including NFS and FFS, need this to 2253 * operate properly either because they assume they 2254 * can issue a read if B_CACHE is not set, or because 2255 * ( for example ) an uncached B_DELWRI might loop due 2256 * to softupdates re-dirtying the buffer. In the latter 2257 * case, B_CACHE is set after the first write completes, 2258 * preventing further loops. 2259 * 2260 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 2261 * above while extending the buffer, we cannot allow the 2262 * buffer to remain with B_CACHE set after the write 2263 * completes or it will represent a corrupt state. To 2264 * deal with this we set B_NOCACHE to scrap the buffer 2265 * after the write. 2266 * 2267 * We might be able to do something fancy, like setting 2268 * B_CACHE in bwrite() except if B_DELWRI is already set, 2269 * so the below call doesn't set B_CACHE, but that gets real 2270 * confusing. This is much easier. 2271 */ 2272 2273 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 2274 bp->b_flags |= B_NOCACHE; 2275 VOP_BWRITE(bp->b_vp, bp); 2276 goto loop; 2277 } 2278 2279 splx(s); 2280 bp->b_flags &= ~B_DONE; 2281 } else { 2282 /* 2283 * Buffer is not in-core, create new buffer. The buffer 2284 * returned by getnewbuf() is locked. Note that the returned 2285 * buffer is also considered valid (not marked B_INVAL). 2286 */ 2287 int bsize, maxsize, vmio; 2288 off_t offset; 2289 2290 if (vn_isdisk(vp, NULL)) 2291 bsize = DEV_BSIZE; 2292 else if (vp->v_mountedhere) 2293 bsize = vp->v_mountedhere->mnt_stat.f_iosize; 2294 else if (vp->v_mount) 2295 bsize = vp->v_mount->mnt_stat.f_iosize; 2296 else 2297 bsize = size; 2298 2299 offset = (off_t)blkno * bsize; 2300 vmio = (VOP_GETVOBJECT(vp, NULL) == 0) && (vp->v_flag & VOBJBUF); 2301 maxsize = vmio ? size + (offset & PAGE_MASK) : size; 2302 maxsize = imax(maxsize, bsize); 2303 2304 if ((bp = getnewbuf(slpflag, slptimeo, size, maxsize)) == NULL) { 2305 if (slpflag || slptimeo) { 2306 splx(s); 2307 return NULL; 2308 } 2309 goto loop; 2310 } 2311 2312 /* 2313 * This code is used to make sure that a buffer is not 2314 * created while the getnewbuf routine is blocked. 2315 * This can be a problem whether the vnode is locked or not. 2316 * If the buffer is created out from under us, we have to 2317 * throw away the one we just created. There is now window 2318 * race because we are safely running at splbio() from the 2319 * point of the duplicate buffer creation through to here, 2320 * and we've locked the buffer. 2321 */ 2322 if (gbincore(vp, blkno)) { 2323 bp->b_flags |= B_INVAL; 2324 brelse(bp); 2325 goto loop; 2326 } 2327 2328 /* 2329 * Insert the buffer into the hash, so that it can 2330 * be found by incore. 2331 */ 2332 bp->b_blkno = bp->b_lblkno = blkno; 2333 bp->b_offset = offset; 2334 2335 bgetvp(vp, bp); 2336 LIST_REMOVE(bp, b_hash); 2337 bh = bufhash(vp, blkno); 2338 LIST_INSERT_HEAD(bh, bp, b_hash); 2339 2340 /* 2341 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 2342 * buffer size starts out as 0, B_CACHE will be set by 2343 * allocbuf() for the VMIO case prior to it testing the 2344 * backing store for validity. 2345 */ 2346 2347 if (vmio) { 2348 bp->b_flags |= B_VMIO; 2349 #if defined(VFS_BIO_DEBUG) 2350 if (vn_canvmio(vp) != TRUE) 2351 printf("getblk: vmioing file type %d???\n", vp->v_type); 2352 #endif 2353 } else { 2354 bp->b_flags &= ~B_VMIO; 2355 } 2356 2357 allocbuf(bp, size); 2358 2359 splx(s); 2360 bp->b_flags &= ~B_DONE; 2361 } 2362 return (bp); 2363 } 2364 2365 /* 2366 * Get an empty, disassociated buffer of given size. The buffer is initially 2367 * set to B_INVAL. 2368 * 2369 * spl protection is not required for the allocbuf() call because races are 2370 * impossible here. 2371 */ 2372 struct buf * 2373 geteblk(int size) 2374 { 2375 struct buf *bp; 2376 int s; 2377 int maxsize; 2378 2379 maxsize = (size + BKVAMASK) & ~BKVAMASK; 2380 2381 s = splbio(); 2382 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0); 2383 splx(s); 2384 allocbuf(bp, size); 2385 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 2386 return (bp); 2387 } 2388 2389 2390 /* 2391 * This code constitutes the buffer memory from either anonymous system 2392 * memory (in the case of non-VMIO operations) or from an associated 2393 * VM object (in the case of VMIO operations). This code is able to 2394 * resize a buffer up or down. 2395 * 2396 * Note that this code is tricky, and has many complications to resolve 2397 * deadlock or inconsistant data situations. Tread lightly!!! 2398 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 2399 * the caller. Calling this code willy nilly can result in the loss of data. 2400 * 2401 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 2402 * B_CACHE for the non-VMIO case. 2403 * 2404 * This routine does not need to be called at splbio() but you must own the 2405 * buffer. 2406 */ 2407 int 2408 allocbuf(struct buf *bp, int size) 2409 { 2410 int newbsize, mbsize; 2411 int i; 2412 2413 if (BUF_REFCNT(bp) == 0) 2414 panic("allocbuf: buffer not busy"); 2415 2416 if (bp->b_kvasize < size) 2417 panic("allocbuf: buffer too small"); 2418 2419 if ((bp->b_flags & B_VMIO) == 0) { 2420 caddr_t origbuf; 2421 int origbufsize; 2422 /* 2423 * Just get anonymous memory from the kernel. Don't 2424 * mess with B_CACHE. 2425 */ 2426 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2427 #if !defined(NO_B_MALLOC) 2428 if (bp->b_flags & B_MALLOC) 2429 newbsize = mbsize; 2430 else 2431 #endif 2432 newbsize = round_page(size); 2433 2434 if (newbsize < bp->b_bufsize) { 2435 #if !defined(NO_B_MALLOC) 2436 /* 2437 * malloced buffers are not shrunk 2438 */ 2439 if (bp->b_flags & B_MALLOC) { 2440 if (newbsize) { 2441 bp->b_bcount = size; 2442 } else { 2443 free(bp->b_data, M_BIOBUF); 2444 if (bp->b_bufsize) { 2445 bufmallocspace -= bp->b_bufsize; 2446 bufspacewakeup(); 2447 bp->b_bufsize = 0; 2448 } 2449 bp->b_data = bp->b_kvabase; 2450 bp->b_bcount = 0; 2451 bp->b_flags &= ~B_MALLOC; 2452 } 2453 return 1; 2454 } 2455 #endif 2456 vm_hold_free_pages( 2457 bp, 2458 (vm_offset_t) bp->b_data + newbsize, 2459 (vm_offset_t) bp->b_data + bp->b_bufsize); 2460 } else if (newbsize > bp->b_bufsize) { 2461 #if !defined(NO_B_MALLOC) 2462 /* 2463 * We only use malloced memory on the first allocation. 2464 * and revert to page-allocated memory when the buffer 2465 * grows. 2466 */ 2467 if ( (bufmallocspace < maxbufmallocspace) && 2468 (bp->b_bufsize == 0) && 2469 (mbsize <= PAGE_SIZE/2)) { 2470 2471 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 2472 bp->b_bufsize = mbsize; 2473 bp->b_bcount = size; 2474 bp->b_flags |= B_MALLOC; 2475 bufmallocspace += mbsize; 2476 return 1; 2477 } 2478 #endif 2479 origbuf = NULL; 2480 origbufsize = 0; 2481 #if !defined(NO_B_MALLOC) 2482 /* 2483 * If the buffer is growing on its other-than-first allocation, 2484 * then we revert to the page-allocation scheme. 2485 */ 2486 if (bp->b_flags & B_MALLOC) { 2487 origbuf = bp->b_data; 2488 origbufsize = bp->b_bufsize; 2489 bp->b_data = bp->b_kvabase; 2490 if (bp->b_bufsize) { 2491 bufmallocspace -= bp->b_bufsize; 2492 bufspacewakeup(); 2493 bp->b_bufsize = 0; 2494 } 2495 bp->b_flags &= ~B_MALLOC; 2496 newbsize = round_page(newbsize); 2497 } 2498 #endif 2499 vm_hold_load_pages( 2500 bp, 2501 (vm_offset_t) bp->b_data + bp->b_bufsize, 2502 (vm_offset_t) bp->b_data + newbsize); 2503 #if !defined(NO_B_MALLOC) 2504 if (origbuf) { 2505 bcopy(origbuf, bp->b_data, origbufsize); 2506 free(origbuf, M_BIOBUF); 2507 } 2508 #endif 2509 } 2510 } else { 2511 vm_page_t m; 2512 int desiredpages; 2513 2514 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2515 desiredpages = (size == 0) ? 0 : 2516 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 2517 2518 #if !defined(NO_B_MALLOC) 2519 if (bp->b_flags & B_MALLOC) 2520 panic("allocbuf: VMIO buffer can't be malloced"); 2521 #endif 2522 /* 2523 * Set B_CACHE initially if buffer is 0 length or will become 2524 * 0-length. 2525 */ 2526 if (size == 0 || bp->b_bufsize == 0) 2527 bp->b_flags |= B_CACHE; 2528 2529 if (newbsize < bp->b_bufsize) { 2530 /* 2531 * DEV_BSIZE aligned new buffer size is less then the 2532 * DEV_BSIZE aligned existing buffer size. Figure out 2533 * if we have to remove any pages. 2534 */ 2535 if (desiredpages < bp->b_xio.xio_npages) { 2536 for (i = desiredpages; i < bp->b_xio.xio_npages; i++) { 2537 /* 2538 * the page is not freed here -- it 2539 * is the responsibility of 2540 * vnode_pager_setsize 2541 */ 2542 m = bp->b_xio.xio_pages[i]; 2543 KASSERT(m != bogus_page, 2544 ("allocbuf: bogus page found")); 2545 while (vm_page_sleep_busy(m, TRUE, "biodep")) 2546 ; 2547 2548 bp->b_xio.xio_pages[i] = NULL; 2549 vm_page_unwire(m, 0); 2550 } 2551 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) + 2552 (desiredpages << PAGE_SHIFT), (bp->b_xio.xio_npages - desiredpages)); 2553 bp->b_xio.xio_npages = desiredpages; 2554 } 2555 } else if (size > bp->b_bcount) { 2556 /* 2557 * We are growing the buffer, possibly in a 2558 * byte-granular fashion. 2559 */ 2560 struct vnode *vp; 2561 vm_object_t obj; 2562 vm_offset_t toff; 2563 vm_offset_t tinc; 2564 int s; 2565 2566 /* 2567 * Step 1, bring in the VM pages from the object, 2568 * allocating them if necessary. We must clear 2569 * B_CACHE if these pages are not valid for the 2570 * range covered by the buffer. 2571 * 2572 * spl protection is required to protect against 2573 * interrupts unbusying and freeing pages between 2574 * our vm_page_lookup() and our busycheck/wiring 2575 * call. 2576 */ 2577 vp = bp->b_vp; 2578 VOP_GETVOBJECT(vp, &obj); 2579 2580 s = splbio(); 2581 while (bp->b_xio.xio_npages < desiredpages) { 2582 vm_page_t m; 2583 vm_pindex_t pi; 2584 2585 pi = OFF_TO_IDX(bp->b_offset) + bp->b_xio.xio_npages; 2586 if ((m = vm_page_lookup(obj, pi)) == NULL) { 2587 /* 2588 * note: must allocate system pages 2589 * since blocking here could intefere 2590 * with paging I/O, no matter which 2591 * process we are. 2592 */ 2593 m = vm_page_alloc(obj, pi, VM_ALLOC_NORMAL | VM_ALLOC_SYSTEM); 2594 if (m == NULL) { 2595 vm_wait(); 2596 vm_pageout_deficit += desiredpages - 2597 bp->b_xio.xio_npages; 2598 } else { 2599 vm_page_wire(m); 2600 vm_page_wakeup(m); 2601 bp->b_flags &= ~B_CACHE; 2602 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 2603 ++bp->b_xio.xio_npages; 2604 } 2605 continue; 2606 } 2607 2608 /* 2609 * We found a page. If we have to sleep on it, 2610 * retry because it might have gotten freed out 2611 * from under us. 2612 * 2613 * We can only test PG_BUSY here. Blocking on 2614 * m->busy might lead to a deadlock: 2615 * 2616 * vm_fault->getpages->cluster_read->allocbuf 2617 * 2618 */ 2619 2620 if (vm_page_sleep_busy(m, FALSE, "pgtblk")) 2621 continue; 2622 2623 /* 2624 * We have a good page. Should we wakeup the 2625 * page daemon? 2626 */ 2627 if ((curthread != pagethread) && 2628 ((m->queue - m->pc) == PQ_CACHE) && 2629 ((vmstats.v_free_count + vmstats.v_cache_count) < 2630 (vmstats.v_free_min + vmstats.v_cache_min))) { 2631 pagedaemon_wakeup(); 2632 } 2633 vm_page_flag_clear(m, PG_ZERO); 2634 vm_page_wire(m); 2635 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 2636 ++bp->b_xio.xio_npages; 2637 } 2638 splx(s); 2639 2640 /* 2641 * Step 2. We've loaded the pages into the buffer, 2642 * we have to figure out if we can still have B_CACHE 2643 * set. Note that B_CACHE is set according to the 2644 * byte-granular range ( bcount and size ), new the 2645 * aligned range ( newbsize ). 2646 * 2647 * The VM test is against m->valid, which is DEV_BSIZE 2648 * aligned. Needless to say, the validity of the data 2649 * needs to also be DEV_BSIZE aligned. Note that this 2650 * fails with NFS if the server or some other client 2651 * extends the file's EOF. If our buffer is resized, 2652 * B_CACHE may remain set! XXX 2653 */ 2654 2655 toff = bp->b_bcount; 2656 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 2657 2658 while ((bp->b_flags & B_CACHE) && toff < size) { 2659 vm_pindex_t pi; 2660 2661 if (tinc > (size - toff)) 2662 tinc = size - toff; 2663 2664 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 2665 PAGE_SHIFT; 2666 2667 vfs_buf_test_cache( 2668 bp, 2669 bp->b_offset, 2670 toff, 2671 tinc, 2672 bp->b_xio.xio_pages[pi] 2673 ); 2674 toff += tinc; 2675 tinc = PAGE_SIZE; 2676 } 2677 2678 /* 2679 * Step 3, fixup the KVM pmap. Remember that 2680 * bp->b_data is relative to bp->b_offset, but 2681 * bp->b_offset may be offset into the first page. 2682 */ 2683 2684 bp->b_data = (caddr_t) 2685 trunc_page((vm_offset_t)bp->b_data); 2686 pmap_qenter( 2687 (vm_offset_t)bp->b_data, 2688 bp->b_xio.xio_pages, 2689 bp->b_xio.xio_npages 2690 ); 2691 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 2692 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 2693 } 2694 } 2695 if (newbsize < bp->b_bufsize) 2696 bufspacewakeup(); 2697 bp->b_bufsize = newbsize; /* actual buffer allocation */ 2698 bp->b_bcount = size; /* requested buffer size */ 2699 return 1; 2700 } 2701 2702 /* 2703 * biowait: 2704 * 2705 * Wait for buffer I/O completion, returning error status. The buffer 2706 * is left locked and B_DONE on return. B_EINTR is converted into a EINTR 2707 * error and cleared. 2708 */ 2709 int 2710 biowait(struct buf * bp) 2711 { 2712 int s; 2713 2714 s = splbio(); 2715 while ((bp->b_flags & B_DONE) == 0) { 2716 #if defined(NO_SCHEDULE_MODS) 2717 tsleep(bp, 0, "biowait", 0); 2718 #else 2719 if (bp->b_flags & B_READ) 2720 tsleep(bp, 0, "biord", 0); 2721 else 2722 tsleep(bp, 0, "biowr", 0); 2723 #endif 2724 } 2725 splx(s); 2726 if (bp->b_flags & B_EINTR) { 2727 bp->b_flags &= ~B_EINTR; 2728 return (EINTR); 2729 } 2730 if (bp->b_flags & B_ERROR) { 2731 return (bp->b_error ? bp->b_error : EIO); 2732 } else { 2733 return (0); 2734 } 2735 } 2736 2737 /* 2738 * biodone: 2739 * 2740 * Finish I/O on a buffer, optionally calling a completion function. 2741 * This is usually called from an interrupt so process blocking is 2742 * not allowed. 2743 * 2744 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 2745 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 2746 * assuming B_INVAL is clear. 2747 * 2748 * For the VMIO case, we set B_CACHE if the op was a read and no 2749 * read error occured, or if the op was a write. B_CACHE is never 2750 * set if the buffer is invalid or otherwise uncacheable. 2751 * 2752 * biodone does not mess with B_INVAL, allowing the I/O routine or the 2753 * initiator to leave B_INVAL set to brelse the buffer out of existance 2754 * in the biodone routine. 2755 * 2756 * b_dev is required to be reinitialized prior to the top level strategy 2757 * call in a device stack. To avoid improper reuse, biodone() sets 2758 * b_dev to NODEV. 2759 */ 2760 void 2761 biodone(struct buf *bp) 2762 { 2763 int s, error; 2764 2765 s = splbio(); 2766 2767 KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp, BUF_REFCNT(bp))); 2768 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 2769 2770 bp->b_flags |= B_DONE; 2771 bp->b_dev = NODEV; 2772 runningbufwakeup(bp); 2773 2774 if (bp->b_flags & B_FREEBUF) { 2775 brelse(bp); 2776 splx(s); 2777 return; 2778 } 2779 2780 if ((bp->b_flags & B_READ) == 0) { 2781 vwakeup(bp); 2782 } 2783 2784 /* call optional completion function if requested */ 2785 if (bp->b_flags & B_CALL) { 2786 bp->b_flags &= ~B_CALL; 2787 (*bp->b_iodone) (bp); 2788 splx(s); 2789 return; 2790 } 2791 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_complete) 2792 (*bioops.io_complete)(bp); 2793 2794 if (bp->b_flags & B_VMIO) { 2795 int i; 2796 vm_ooffset_t foff; 2797 vm_page_t m; 2798 vm_object_t obj; 2799 int iosize; 2800 struct vnode *vp = bp->b_vp; 2801 2802 error = VOP_GETVOBJECT(vp, &obj); 2803 2804 #if defined(VFS_BIO_DEBUG) 2805 if (vp->v_holdcnt == 0) { 2806 panic("biodone: zero vnode hold count"); 2807 } 2808 2809 if (error) { 2810 panic("biodone: missing VM object"); 2811 } 2812 2813 if ((vp->v_flag & VOBJBUF) == 0) { 2814 panic("biodone: vnode is not setup for merged cache"); 2815 } 2816 #endif 2817 2818 foff = bp->b_offset; 2819 KASSERT(bp->b_offset != NOOFFSET, 2820 ("biodone: no buffer offset")); 2821 2822 if (error) { 2823 panic("biodone: no object"); 2824 } 2825 #if defined(VFS_BIO_DEBUG) 2826 if (obj->paging_in_progress < bp->b_xio.xio_npages) { 2827 printf("biodone: paging in progress(%d) < bp->b_xio.xio_npages(%d)\n", 2828 obj->paging_in_progress, bp->b_xio.xio_npages); 2829 } 2830 #endif 2831 2832 /* 2833 * Set B_CACHE if the op was a normal read and no error 2834 * occured. B_CACHE is set for writes in the b*write() 2835 * routines. 2836 */ 2837 iosize = bp->b_bcount - bp->b_resid; 2838 if ((bp->b_flags & (B_READ|B_FREEBUF|B_INVAL|B_NOCACHE|B_ERROR)) == B_READ) { 2839 bp->b_flags |= B_CACHE; 2840 } 2841 2842 for (i = 0; i < bp->b_xio.xio_npages; i++) { 2843 int bogusflag = 0; 2844 int resid; 2845 2846 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 2847 if (resid > iosize) 2848 resid = iosize; 2849 2850 /* 2851 * cleanup bogus pages, restoring the originals. Since 2852 * the originals should still be wired, we don't have 2853 * to worry about interrupt/freeing races destroying 2854 * the VM object association. 2855 */ 2856 m = bp->b_xio.xio_pages[i]; 2857 if (m == bogus_page) { 2858 bogusflag = 1; 2859 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 2860 if (m == NULL) 2861 panic("biodone: page disappeared"); 2862 bp->b_xio.xio_pages[i] = m; 2863 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 2864 bp->b_xio.xio_pages, bp->b_xio.xio_npages); 2865 } 2866 #if defined(VFS_BIO_DEBUG) 2867 if (OFF_TO_IDX(foff) != m->pindex) { 2868 printf( 2869 "biodone: foff(%lu)/m->pindex(%d) mismatch\n", 2870 (unsigned long)foff, m->pindex); 2871 } 2872 #endif 2873 2874 /* 2875 * In the write case, the valid and clean bits are 2876 * already changed correctly ( see bdwrite() ), so we 2877 * only need to do this here in the read case. 2878 */ 2879 if ((bp->b_flags & B_READ) && !bogusflag && resid > 0) { 2880 vfs_page_set_valid(bp, foff, i, m); 2881 } 2882 vm_page_flag_clear(m, PG_ZERO); 2883 2884 /* 2885 * when debugging new filesystems or buffer I/O methods, this 2886 * is the most common error that pops up. if you see this, you 2887 * have not set the page busy flag correctly!!! 2888 */ 2889 if (m->busy == 0) { 2890 printf("biodone: page busy < 0, " 2891 "pindex: %d, foff: 0x(%x,%x), " 2892 "resid: %d, index: %d\n", 2893 (int) m->pindex, (int)(foff >> 32), 2894 (int) foff & 0xffffffff, resid, i); 2895 if (!vn_isdisk(vp, NULL)) 2896 printf(" iosize: %ld, lblkno: %d, flags: 0x%lx, npages: %d\n", 2897 bp->b_vp->v_mount->mnt_stat.f_iosize, 2898 (int) bp->b_lblkno, 2899 bp->b_flags, bp->b_xio.xio_npages); 2900 else 2901 printf(" VDEV, lblkno: %d, flags: 0x%lx, npages: %d\n", 2902 (int) bp->b_lblkno, 2903 bp->b_flags, bp->b_xio.xio_npages); 2904 printf(" valid: 0x%x, dirty: 0x%x, wired: %d\n", 2905 m->valid, m->dirty, m->wire_count); 2906 panic("biodone: page busy < 0"); 2907 } 2908 vm_page_io_finish(m); 2909 vm_object_pip_subtract(obj, 1); 2910 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2911 iosize -= resid; 2912 } 2913 if (obj) 2914 vm_object_pip_wakeupn(obj, 0); 2915 } 2916 2917 /* 2918 * For asynchronous completions, release the buffer now. The brelse 2919 * will do a wakeup there if necessary - so no need to do a wakeup 2920 * here in the async case. The sync case always needs to do a wakeup. 2921 */ 2922 2923 if (bp->b_flags & B_ASYNC) { 2924 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR | B_RELBUF)) != 0) 2925 brelse(bp); 2926 else 2927 bqrelse(bp); 2928 } else { 2929 wakeup(bp); 2930 } 2931 splx(s); 2932 } 2933 2934 /* 2935 * This routine is called in lieu of iodone in the case of 2936 * incomplete I/O. This keeps the busy status for pages 2937 * consistant. 2938 */ 2939 void 2940 vfs_unbusy_pages(struct buf *bp) 2941 { 2942 int i; 2943 2944 runningbufwakeup(bp); 2945 if (bp->b_flags & B_VMIO) { 2946 struct vnode *vp = bp->b_vp; 2947 vm_object_t obj; 2948 2949 VOP_GETVOBJECT(vp, &obj); 2950 2951 for (i = 0; i < bp->b_xio.xio_npages; i++) { 2952 vm_page_t m = bp->b_xio.xio_pages[i]; 2953 2954 /* 2955 * When restoring bogus changes the original pages 2956 * should still be wired, so we are in no danger of 2957 * losing the object association and do not need 2958 * spl protection particularly. 2959 */ 2960 if (m == bogus_page) { 2961 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 2962 if (!m) { 2963 panic("vfs_unbusy_pages: page missing"); 2964 } 2965 bp->b_xio.xio_pages[i] = m; 2966 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 2967 bp->b_xio.xio_pages, bp->b_xio.xio_npages); 2968 } 2969 vm_object_pip_subtract(obj, 1); 2970 vm_page_flag_clear(m, PG_ZERO); 2971 vm_page_io_finish(m); 2972 } 2973 vm_object_pip_wakeupn(obj, 0); 2974 } 2975 } 2976 2977 /* 2978 * vfs_page_set_valid: 2979 * 2980 * Set the valid bits in a page based on the supplied offset. The 2981 * range is restricted to the buffer's size. 2982 * 2983 * This routine is typically called after a read completes. 2984 */ 2985 static void 2986 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m) 2987 { 2988 vm_ooffset_t soff, eoff; 2989 2990 /* 2991 * Start and end offsets in buffer. eoff - soff may not cross a 2992 * page boundry or cross the end of the buffer. The end of the 2993 * buffer, in this case, is our file EOF, not the allocation size 2994 * of the buffer. 2995 */ 2996 soff = off; 2997 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2998 if (eoff > bp->b_offset + bp->b_bcount) 2999 eoff = bp->b_offset + bp->b_bcount; 3000 3001 /* 3002 * Set valid range. This is typically the entire buffer and thus the 3003 * entire page. 3004 */ 3005 if (eoff > soff) { 3006 vm_page_set_validclean( 3007 m, 3008 (vm_offset_t) (soff & PAGE_MASK), 3009 (vm_offset_t) (eoff - soff) 3010 ); 3011 } 3012 } 3013 3014 /* 3015 * This routine is called before a device strategy routine. 3016 * It is used to tell the VM system that paging I/O is in 3017 * progress, and treat the pages associated with the buffer 3018 * almost as being PG_BUSY. Also the object paging_in_progress 3019 * flag is handled to make sure that the object doesn't become 3020 * inconsistant. 3021 * 3022 * Since I/O has not been initiated yet, certain buffer flags 3023 * such as B_ERROR or B_INVAL may be in an inconsistant state 3024 * and should be ignored. 3025 */ 3026 void 3027 vfs_busy_pages(struct buf *bp, int clear_modify) 3028 { 3029 int i, bogus; 3030 3031 if (bp->b_flags & B_VMIO) { 3032 struct vnode *vp = bp->b_vp; 3033 vm_object_t obj; 3034 vm_ooffset_t foff; 3035 3036 VOP_GETVOBJECT(vp, &obj); 3037 foff = bp->b_offset; 3038 KASSERT(bp->b_offset != NOOFFSET, 3039 ("vfs_busy_pages: no buffer offset")); 3040 vfs_setdirty(bp); 3041 3042 retry: 3043 for (i = 0; i < bp->b_xio.xio_npages; i++) { 3044 vm_page_t m = bp->b_xio.xio_pages[i]; 3045 if (vm_page_sleep_busy(m, FALSE, "vbpage")) 3046 goto retry; 3047 } 3048 3049 bogus = 0; 3050 for (i = 0; i < bp->b_xio.xio_npages; i++) { 3051 vm_page_t m = bp->b_xio.xio_pages[i]; 3052 3053 vm_page_flag_clear(m, PG_ZERO); 3054 if ((bp->b_flags & B_CLUSTER) == 0) { 3055 vm_object_pip_add(obj, 1); 3056 vm_page_io_start(m); 3057 } 3058 3059 /* 3060 * When readying a buffer for a read ( i.e 3061 * clear_modify == 0 ), it is important to do 3062 * bogus_page replacement for valid pages in 3063 * partially instantiated buffers. Partially 3064 * instantiated buffers can, in turn, occur when 3065 * reconstituting a buffer from its VM backing store 3066 * base. We only have to do this if B_CACHE is 3067 * clear ( which causes the I/O to occur in the 3068 * first place ). The replacement prevents the read 3069 * I/O from overwriting potentially dirty VM-backed 3070 * pages. XXX bogus page replacement is, uh, bogus. 3071 * It may not work properly with small-block devices. 3072 * We need to find a better way. 3073 */ 3074 3075 vm_page_protect(m, VM_PROT_NONE); 3076 if (clear_modify) 3077 vfs_page_set_valid(bp, foff, i, m); 3078 else if (m->valid == VM_PAGE_BITS_ALL && 3079 (bp->b_flags & B_CACHE) == 0) { 3080 bp->b_xio.xio_pages[i] = bogus_page; 3081 bogus++; 3082 } 3083 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3084 } 3085 if (bogus) 3086 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3087 bp->b_xio.xio_pages, bp->b_xio.xio_npages); 3088 } 3089 3090 /* 3091 * This is the easiest place to put the process accounting for the I/O 3092 * for now. 3093 */ 3094 { 3095 struct proc *p; 3096 3097 if ((p = curthread->td_proc) != NULL) { 3098 if (bp->b_flags & B_READ) 3099 p->p_stats->p_ru.ru_inblock++; 3100 else 3101 p->p_stats->p_ru.ru_oublock++; 3102 } 3103 } 3104 } 3105 3106 /* 3107 * Tell the VM system that the pages associated with this buffer 3108 * are clean. This is used for delayed writes where the data is 3109 * going to go to disk eventually without additional VM intevention. 3110 * 3111 * Note that while we only really need to clean through to b_bcount, we 3112 * just go ahead and clean through to b_bufsize. 3113 */ 3114 static void 3115 vfs_clean_pages(struct buf *bp) 3116 { 3117 int i; 3118 3119 if (bp->b_flags & B_VMIO) { 3120 vm_ooffset_t foff; 3121 3122 foff = bp->b_offset; 3123 KASSERT(bp->b_offset != NOOFFSET, 3124 ("vfs_clean_pages: no buffer offset")); 3125 for (i = 0; i < bp->b_xio.xio_npages; i++) { 3126 vm_page_t m = bp->b_xio.xio_pages[i]; 3127 vm_ooffset_t noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3128 vm_ooffset_t eoff = noff; 3129 3130 if (eoff > bp->b_offset + bp->b_bufsize) 3131 eoff = bp->b_offset + bp->b_bufsize; 3132 vfs_page_set_valid(bp, foff, i, m); 3133 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3134 foff = noff; 3135 } 3136 } 3137 } 3138 3139 /* 3140 * vfs_bio_set_validclean: 3141 * 3142 * Set the range within the buffer to valid and clean. The range is 3143 * relative to the beginning of the buffer, b_offset. Note that b_offset 3144 * itself may be offset from the beginning of the first page. 3145 */ 3146 3147 void 3148 vfs_bio_set_validclean(struct buf *bp, int base, int size) 3149 { 3150 if (bp->b_flags & B_VMIO) { 3151 int i; 3152 int n; 3153 3154 /* 3155 * Fixup base to be relative to beginning of first page. 3156 * Set initial n to be the maximum number of bytes in the 3157 * first page that can be validated. 3158 */ 3159 3160 base += (bp->b_offset & PAGE_MASK); 3161 n = PAGE_SIZE - (base & PAGE_MASK); 3162 3163 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_xio.xio_npages; ++i) { 3164 vm_page_t m = bp->b_xio.xio_pages[i]; 3165 3166 if (n > size) 3167 n = size; 3168 3169 vm_page_set_validclean(m, base & PAGE_MASK, n); 3170 base += n; 3171 size -= n; 3172 n = PAGE_SIZE; 3173 } 3174 } 3175 } 3176 3177 /* 3178 * vfs_bio_clrbuf: 3179 * 3180 * clear a buffer. This routine essentially fakes an I/O, so we need 3181 * to clear B_ERROR and B_INVAL. 3182 * 3183 * Note that while we only theoretically need to clear through b_bcount, 3184 * we go ahead and clear through b_bufsize. 3185 */ 3186 3187 void 3188 vfs_bio_clrbuf(struct buf *bp) 3189 { 3190 int i, mask = 0; 3191 caddr_t sa, ea; 3192 if ((bp->b_flags & (B_VMIO | B_MALLOC)) == B_VMIO) { 3193 bp->b_flags &= ~(B_INVAL|B_ERROR); 3194 if ((bp->b_xio.xio_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 3195 (bp->b_offset & PAGE_MASK) == 0) { 3196 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 3197 if ((bp->b_xio.xio_pages[0]->valid & mask) == mask) { 3198 bp->b_resid = 0; 3199 return; 3200 } 3201 if (((bp->b_xio.xio_pages[0]->flags & PG_ZERO) == 0) && 3202 ((bp->b_xio.xio_pages[0]->valid & mask) == 0)) { 3203 bzero(bp->b_data, bp->b_bufsize); 3204 bp->b_xio.xio_pages[0]->valid |= mask; 3205 bp->b_resid = 0; 3206 return; 3207 } 3208 } 3209 ea = sa = bp->b_data; 3210 for(i=0;i<bp->b_xio.xio_npages;i++,sa=ea) { 3211 int j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; 3212 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); 3213 ea = (caddr_t)(vm_offset_t)ulmin( 3214 (u_long)(vm_offset_t)ea, 3215 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); 3216 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 3217 if ((bp->b_xio.xio_pages[i]->valid & mask) == mask) 3218 continue; 3219 if ((bp->b_xio.xio_pages[i]->valid & mask) == 0) { 3220 if ((bp->b_xio.xio_pages[i]->flags & PG_ZERO) == 0) { 3221 bzero(sa, ea - sa); 3222 } 3223 } else { 3224 for (; sa < ea; sa += DEV_BSIZE, j++) { 3225 if (((bp->b_xio.xio_pages[i]->flags & PG_ZERO) == 0) && 3226 (bp->b_xio.xio_pages[i]->valid & (1<<j)) == 0) 3227 bzero(sa, DEV_BSIZE); 3228 } 3229 } 3230 bp->b_xio.xio_pages[i]->valid |= mask; 3231 vm_page_flag_clear(bp->b_xio.xio_pages[i], PG_ZERO); 3232 } 3233 bp->b_resid = 0; 3234 } else { 3235 clrbuf(bp); 3236 } 3237 } 3238 3239 /* 3240 * vm_hold_load_pages and vm_hold_unload pages get pages into 3241 * a buffers address space. The pages are anonymous and are 3242 * not associated with a file object. 3243 */ 3244 void 3245 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 3246 { 3247 vm_offset_t pg; 3248 vm_page_t p; 3249 int index; 3250 3251 to = round_page(to); 3252 from = round_page(from); 3253 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3254 3255 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3256 3257 tryagain: 3258 3259 /* 3260 * note: must allocate system pages since blocking here 3261 * could intefere with paging I/O, no matter which 3262 * process we are. 3263 */ 3264 p = vm_page_alloc(kernel_object, 3265 ((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 3266 VM_ALLOC_NORMAL | VM_ALLOC_SYSTEM); 3267 if (!p) { 3268 vm_pageout_deficit += (to - from) >> PAGE_SHIFT; 3269 vm_wait(); 3270 goto tryagain; 3271 } 3272 vm_page_wire(p); 3273 p->valid = VM_PAGE_BITS_ALL; 3274 vm_page_flag_clear(p, PG_ZERO); 3275 pmap_kenter(pg, VM_PAGE_TO_PHYS(p)); 3276 bp->b_xio.xio_pages[index] = p; 3277 vm_page_wakeup(p); 3278 } 3279 bp->b_xio.xio_npages = index; 3280 } 3281 3282 void 3283 vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 3284 { 3285 vm_offset_t pg; 3286 vm_page_t p; 3287 int index, newnpages; 3288 3289 from = round_page(from); 3290 to = round_page(to); 3291 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3292 3293 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3294 p = bp->b_xio.xio_pages[index]; 3295 if (p && (index < bp->b_xio.xio_npages)) { 3296 if (p->busy) { 3297 printf("vm_hold_free_pages: blkno: %d, lblkno: %d\n", 3298 bp->b_blkno, bp->b_lblkno); 3299 } 3300 bp->b_xio.xio_pages[index] = NULL; 3301 pmap_kremove(pg); 3302 vm_page_busy(p); 3303 vm_page_unwire(p, 0); 3304 vm_page_free(p); 3305 } 3306 } 3307 bp->b_xio.xio_npages = newnpages; 3308 } 3309 3310 /* 3311 * Map an IO request into kernel virtual address space. 3312 * 3313 * All requests are (re)mapped into kernel VA space. 3314 * Notice that we use b_bufsize for the size of the buffer 3315 * to be mapped. b_bcount might be modified by the driver. 3316 */ 3317 int 3318 vmapbuf(struct buf *bp) 3319 { 3320 caddr_t addr, v, kva; 3321 vm_paddr_t pa; 3322 int pidx; 3323 int i; 3324 struct vm_page *m; 3325 3326 if ((bp->b_flags & B_PHYS) == 0) 3327 panic("vmapbuf"); 3328 if (bp->b_bufsize < 0) 3329 return (-1); 3330 for (v = bp->b_saveaddr, 3331 addr = (caddr_t)trunc_page((vm_offset_t)bp->b_data), 3332 pidx = 0; 3333 addr < bp->b_data + bp->b_bufsize; 3334 addr += PAGE_SIZE, v += PAGE_SIZE, pidx++) { 3335 /* 3336 * Do the vm_fault if needed; do the copy-on-write thing 3337 * when reading stuff off device into memory. 3338 */ 3339 retry: 3340 i = vm_fault_quick((addr >= bp->b_data) ? addr : bp->b_data, 3341 (bp->b_flags&B_READ)?(VM_PROT_READ|VM_PROT_WRITE):VM_PROT_READ); 3342 if (i < 0) { 3343 for (i = 0; i < pidx; ++i) { 3344 vm_page_unhold(bp->b_xio.xio_pages[i]); 3345 bp->b_xio.xio_pages[i] = NULL; 3346 } 3347 return(-1); 3348 } 3349 3350 /* 3351 * WARNING! If sparc support is MFCd in the future this will 3352 * have to be changed from pmap_kextract() to pmap_extract() 3353 * ala -current. 3354 */ 3355 #ifdef __sparc64__ 3356 #error "If MFCing sparc support use pmap_extract" 3357 #endif 3358 pa = pmap_kextract((vm_offset_t)addr); 3359 if (pa == 0) { 3360 printf("vmapbuf: warning, race against user address during I/O"); 3361 goto retry; 3362 } 3363 m = PHYS_TO_VM_PAGE(pa); 3364 vm_page_hold(m); 3365 bp->b_xio.xio_pages[pidx] = m; 3366 } 3367 if (pidx > btoc(MAXPHYS)) 3368 panic("vmapbuf: mapped more than MAXPHYS"); 3369 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_xio.xio_pages, pidx); 3370 3371 kva = bp->b_saveaddr; 3372 bp->b_xio.xio_npages = pidx; 3373 bp->b_saveaddr = bp->b_data; 3374 bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK); 3375 return(0); 3376 } 3377 3378 /* 3379 * Free the io map PTEs associated with this IO operation. 3380 * We also invalidate the TLB entries and restore the original b_addr. 3381 */ 3382 void 3383 vunmapbuf(struct buf *bp) 3384 { 3385 int pidx; 3386 int npages; 3387 vm_page_t *m; 3388 3389 if ((bp->b_flags & B_PHYS) == 0) 3390 panic("vunmapbuf"); 3391 3392 npages = bp->b_xio.xio_npages; 3393 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), 3394 npages); 3395 m = bp->b_xio.xio_pages; 3396 for (pidx = 0; pidx < npages; pidx++) 3397 vm_page_unhold(*m++); 3398 3399 bp->b_data = bp->b_saveaddr; 3400 } 3401 3402 #include "opt_ddb.h" 3403 #ifdef DDB 3404 #include <ddb/ddb.h> 3405 3406 DB_SHOW_COMMAND(buffer, db_show_buffer) 3407 { 3408 /* get args */ 3409 struct buf *bp = (struct buf *)addr; 3410 3411 if (!have_addr) { 3412 db_printf("usage: show buffer <addr>\n"); 3413 return; 3414 } 3415 3416 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS); 3417 db_printf("b_error = %d, b_bufsize = %ld, b_bcount = %ld, " 3418 "b_resid = %ld\nb_dev = (%d,%d), b_data = %p, " 3419 "b_blkno = %d, b_pblkno = %d\n", 3420 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 3421 major(bp->b_dev), minor(bp->b_dev), 3422 bp->b_data, bp->b_blkno, bp->b_pblkno); 3423 if (bp->b_xio.xio_npages) { 3424 int i; 3425 db_printf("b_xio.xio_npages = %d, pages(OBJ, IDX, PA): ", 3426 bp->b_xio.xio_npages); 3427 for (i = 0; i < bp->b_xio.xio_npages; i++) { 3428 vm_page_t m; 3429 m = bp->b_xio.xio_pages[i]; 3430 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 3431 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 3432 if ((i + 1) < bp->b_xio.xio_npages) 3433 db_printf(","); 3434 } 3435 db_printf("\n"); 3436 } 3437 } 3438 #endif /* DDB */ 3439