1 /* 2 * Copyright (c) 1994,1997 John S. Dyson 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice immediately at the beginning of the file, without modification, 10 * this list of conditions, and the following disclaimer. 11 * 2. Absolutely no warranty of function or purpose is made by the author 12 * John S. Dyson. 13 * 14 * $FreeBSD$ 15 */ 16 17 /* 18 * this file contains a new buffer I/O scheme implementing a coherent 19 * VM object and buffer cache scheme. Pains have been taken to make 20 * sure that the performance degradation associated with schemes such 21 * as this is not realized. 22 * 23 * Author: John S. Dyson 24 * Significant help during the development and debugging phases 25 * had been provided by David Greenman, also of the FreeBSD core team. 26 * 27 * see man buf(9) for more info. 28 */ 29 30 #include <sys/param.h> 31 #include <sys/systm.h> 32 #include <sys/bio.h> 33 #include <sys/buf.h> 34 #include <sys/eventhandler.h> 35 #include <sys/lock.h> 36 #include <sys/malloc.h> 37 #include <sys/mount.h> 38 #include <sys/mutex.h> 39 #include <sys/kernel.h> 40 #include <sys/kthread.h> 41 #include <sys/ktr.h> 42 #include <sys/proc.h> 43 #include <sys/reboot.h> 44 #include <sys/resourcevar.h> 45 #include <sys/sysctl.h> 46 #include <sys/vmmeter.h> 47 #include <sys/vnode.h> 48 #include <vm/vm.h> 49 #include <vm/vm_param.h> 50 #include <vm/vm_kern.h> 51 #include <vm/vm_pageout.h> 52 #include <vm/vm_page.h> 53 #include <vm/vm_object.h> 54 #include <vm/vm_extern.h> 55 #include <vm/vm_map.h> 56 57 static MALLOC_DEFINE(M_BIOBUF, "BIO buffer", "BIO buffer"); 58 59 struct bio_ops bioops; /* I/O operation notification */ 60 61 struct buf_ops buf_ops_bio = { 62 "buf_ops_bio", 63 bwrite 64 }; 65 66 /* 67 * XXX buf is global because kern_shutdown.c and ffs_checkoverlap has 68 * carnal knowledge of buffers. This knowledge should be moved to vfs_bio.c. 69 */ 70 struct buf *buf; /* buffer header pool */ 71 struct mtx buftimelock; /* Interlock on setting prio and timo */ 72 73 static void vm_hold_free_pages(struct buf * bp, vm_offset_t from, 74 vm_offset_t to); 75 static void vm_hold_load_pages(struct buf * bp, vm_offset_t from, 76 vm_offset_t to); 77 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, 78 int pageno, vm_page_t m); 79 static void vfs_clean_pages(struct buf * bp); 80 static void vfs_setdirty(struct buf *bp); 81 static void vfs_vmio_release(struct buf *bp); 82 static void vfs_backgroundwritedone(struct buf *bp); 83 static int flushbufqueues(void); 84 static void buf_daemon(void); 85 86 int vmiodirenable = TRUE; 87 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, 88 "Use the VM system for directory writes"); 89 int runningbufspace; 90 SYSCTL_INT(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 91 "Amount of presently outstanding async buffer io"); 92 static int bufspace; 93 SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, 94 "KVA memory used for bufs"); 95 static int maxbufspace; 96 SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0, 97 "Maximum allowed value of bufspace (including buf_daemon)"); 98 static int bufmallocspace; 99 SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 100 "Amount of malloced memory for buffers"); 101 static int maxbufmallocspace; 102 SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0, 103 "Maximum amount of malloced memory for buffers"); 104 static int lobufspace; 105 SYSCTL_INT(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0, 106 "Minimum amount of buffers we want to have"); 107 static int hibufspace; 108 SYSCTL_INT(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0, 109 "Maximum allowed value of bufspace (excluding buf_daemon)"); 110 static int bufreusecnt; 111 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0, 112 "Number of times we have reused a buffer"); 113 static int buffreekvacnt; 114 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0, 115 "Number of times we have freed the KVA space from some buffer"); 116 static int bufdefragcnt; 117 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0, 118 "Number of times we have had to repeat buffer allocation to defragment"); 119 static int lorunningspace; 120 SYSCTL_INT(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0, 121 "Minimum preferred space used for in-progress I/O"); 122 static int hirunningspace; 123 SYSCTL_INT(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0, 124 "Maximum amount of space to use for in-progress I/O"); 125 static int numdirtybuffers; 126 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0, 127 "Number of buffers that are dirty (has unwritten changes) at the moment"); 128 static int lodirtybuffers; 129 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0, 130 "How many buffers we want to have free before bufdaemon can sleep"); 131 static int hidirtybuffers; 132 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0, 133 "When the number of dirty buffers is considered severe"); 134 static int numfreebuffers; 135 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, 136 "Number of free buffers"); 137 static int lofreebuffers; 138 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0, 139 "XXX Unused"); 140 static int hifreebuffers; 141 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0, 142 "XXX Complicatedly unused"); 143 static int getnewbufcalls; 144 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0, 145 "Number of calls to getnewbuf"); 146 static int getnewbufrestarts; 147 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0, 148 "Number of times getnewbuf has had to restart a buffer aquisition"); 149 static int dobkgrdwrite = 1; 150 SYSCTL_INT(_debug, OID_AUTO, dobkgrdwrite, CTLFLAG_RW, &dobkgrdwrite, 0, 151 "Do background writes (honoring the BX_BKGRDWRITE flag)?"); 152 153 /* 154 * Wakeup point for bufdaemon, as well as indicator of whether it is already 155 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it 156 * is idling. 157 */ 158 static int bd_request; 159 160 /* 161 * bogus page -- for I/O to/from partially complete buffers 162 * this is a temporary solution to the problem, but it is not 163 * really that bad. it would be better to split the buffer 164 * for input in the case of buffers partially already in memory, 165 * but the code is intricate enough already. 166 */ 167 vm_page_t bogus_page; 168 169 /* 170 * Offset for bogus_page. 171 * XXX bogus_offset should be local to bufinit 172 */ 173 static vm_offset_t bogus_offset; 174 175 /* 176 * Synchronization (sleep/wakeup) variable for active buffer space requests. 177 * Set when wait starts, cleared prior to wakeup(). 178 * Used in runningbufwakeup() and waitrunningbufspace(). 179 */ 180 static int runningbufreq; 181 182 /* 183 * Synchronization (sleep/wakeup) variable for buffer requests. 184 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done 185 * by and/or. 186 * Used in numdirtywakeup(), bufspacewakeup(), bufcountwakeup(), bwillwrite(), 187 * getnewbuf(), and getblk(). 188 */ 189 static int needsbuffer; 190 191 /* 192 * Mask for index into the buffer hash table, which needs to be power of 2 in 193 * size. Set in kern_vfs_bio_buffer_alloc. 194 */ 195 static int bufhashmask; 196 197 /* 198 * Hash table for all buffers, with a linked list hanging from each table 199 * entry. Set in kern_vfs_bio_buffer_alloc, initialized in buf_init. 200 */ 201 static LIST_HEAD(bufhashhdr, buf) *bufhashtbl; 202 203 /* 204 * Somewhere to store buffers when they are not in another list, to always 205 * have them in a list (and thus being able to use the same set of operations 206 * on them.) 207 */ 208 static struct bufhashhdr invalhash; 209 210 /* 211 * Definitions for the buffer free lists. 212 */ 213 #define BUFFER_QUEUES 6 /* number of free buffer queues */ 214 215 #define QUEUE_NONE 0 /* on no queue */ 216 #define QUEUE_LOCKED 1 /* locked buffers */ 217 #define QUEUE_CLEAN 2 /* non-B_DELWRI buffers */ 218 #define QUEUE_DIRTY 3 /* B_DELWRI buffers */ 219 #define QUEUE_EMPTYKVA 4 /* empty buffer headers w/KVA assignment */ 220 #define QUEUE_EMPTY 5 /* empty buffer headers */ 221 222 /* Queues for free buffers with various properties */ 223 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } }; 224 /* 225 * Single global constant for BUF_WMESG, to avoid getting multiple references. 226 * buf_wmesg is referred from macros. 227 */ 228 const char *buf_wmesg = BUF_WMESG; 229 230 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 231 #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */ 232 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ 233 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 234 235 /* 236 * Buffer hash table code. Note that the logical block scans linearly, which 237 * gives us some L1 cache locality. 238 */ 239 240 static __inline 241 struct bufhashhdr * 242 bufhash(struct vnode *vnp, daddr_t bn) 243 { 244 return(&bufhashtbl[(((uintptr_t)(vnp) >> 7) + (int)bn) & bufhashmask]); 245 } 246 247 /* 248 * numdirtywakeup: 249 * 250 * If someone is blocked due to there being too many dirty buffers, 251 * and numdirtybuffers is now reasonable, wake them up. 252 */ 253 254 static __inline void 255 numdirtywakeup(int level) 256 { 257 if (numdirtybuffers <= level) { 258 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) { 259 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH; 260 wakeup(&needsbuffer); 261 } 262 } 263 } 264 265 /* 266 * bufspacewakeup: 267 * 268 * Called when buffer space is potentially available for recovery. 269 * getnewbuf() will block on this flag when it is unable to free 270 * sufficient buffer space. Buffer space becomes recoverable when 271 * bp's get placed back in the queues. 272 */ 273 274 static __inline void 275 bufspacewakeup(void) 276 { 277 /* 278 * If someone is waiting for BUF space, wake them up. Even 279 * though we haven't freed the kva space yet, the waiting 280 * process will be able to now. 281 */ 282 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) { 283 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE; 284 wakeup(&needsbuffer); 285 } 286 } 287 288 /* 289 * runningbufwakeup() - in-progress I/O accounting. 290 * 291 */ 292 static __inline void 293 runningbufwakeup(struct buf *bp) 294 { 295 if (bp->b_runningbufspace) { 296 runningbufspace -= bp->b_runningbufspace; 297 bp->b_runningbufspace = 0; 298 if (runningbufreq && runningbufspace <= lorunningspace) { 299 runningbufreq = 0; 300 wakeup(&runningbufreq); 301 } 302 } 303 } 304 305 /* 306 * bufcountwakeup: 307 * 308 * Called when a buffer has been added to one of the free queues to 309 * account for the buffer and to wakeup anyone waiting for free buffers. 310 * This typically occurs when large amounts of metadata are being handled 311 * by the buffer cache ( else buffer space runs out first, usually ). 312 */ 313 314 static __inline void 315 bufcountwakeup(void) 316 { 317 ++numfreebuffers; 318 if (needsbuffer) { 319 needsbuffer &= ~VFS_BIO_NEED_ANY; 320 if (numfreebuffers >= hifreebuffers) 321 needsbuffer &= ~VFS_BIO_NEED_FREE; 322 wakeup(&needsbuffer); 323 } 324 } 325 326 /* 327 * waitrunningbufspace() 328 * 329 * runningbufspace is a measure of the amount of I/O currently 330 * running. This routine is used in async-write situations to 331 * prevent creating huge backups of pending writes to a device. 332 * Only asynchronous writes are governed by this function. 333 * 334 * Reads will adjust runningbufspace, but will not block based on it. 335 * The read load has a side effect of reducing the allowed write load. 336 * 337 * This does NOT turn an async write into a sync write. It waits 338 * for earlier writes to complete and generally returns before the 339 * caller's write has reached the device. 340 */ 341 static __inline void 342 waitrunningbufspace(void) 343 { 344 /* 345 * XXX race against wakeup interrupt, currently 346 * protected by Giant. FIXME! 347 */ 348 while (runningbufspace > hirunningspace) { 349 ++runningbufreq; 350 tsleep(&runningbufreq, PVM, "wdrain", 0); 351 } 352 } 353 354 355 /* 356 * vfs_buf_test_cache: 357 * 358 * Called when a buffer is extended. This function clears the B_CACHE 359 * bit if the newly extended portion of the buffer does not contain 360 * valid data. 361 */ 362 static __inline__ 363 void 364 vfs_buf_test_cache(struct buf *bp, 365 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 366 vm_page_t m) 367 { 368 GIANT_REQUIRED; 369 370 if (bp->b_flags & B_CACHE) { 371 int base = (foff + off) & PAGE_MASK; 372 if (vm_page_is_valid(m, base, size) == 0) 373 bp->b_flags &= ~B_CACHE; 374 } 375 } 376 377 /* Wake up the buffer deamon if necessary */ 378 static __inline__ 379 void 380 bd_wakeup(int dirtybuflevel) 381 { 382 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) { 383 bd_request = 1; 384 wakeup(&bd_request); 385 } 386 } 387 388 /* 389 * bd_speedup - speedup the buffer cache flushing code 390 */ 391 392 static __inline__ 393 void 394 bd_speedup(void) 395 { 396 bd_wakeup(1); 397 } 398 399 /* 400 * Calculating buffer cache scaling values and reserve space for buffer 401 * headers. This is called during low level kernel initialization and 402 * may be called more then once. We CANNOT write to the memory area 403 * being reserved at this time. 404 */ 405 caddr_t 406 kern_vfs_bio_buffer_alloc(caddr_t v, int physmem_est) 407 { 408 /* 409 * physmem_est is in pages. Convert it to kilobytes (assumes 410 * PAGE_SIZE is >= 1K) 411 */ 412 physmem_est = physmem_est * (PAGE_SIZE / 1024); 413 414 /* 415 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 416 * For the first 64MB of ram nominally allocate sufficient buffers to 417 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 418 * buffers to cover 1/20 of our ram over 64MB. When auto-sizing 419 * the buffer cache we limit the eventual kva reservation to 420 * maxbcache bytes. 421 * 422 * factor represents the 1/4 x ram conversion. 423 */ 424 if (nbuf == 0) { 425 int factor = 4 * BKVASIZE / 1024; 426 427 nbuf = 50; 428 if (physmem_est > 4096) 429 nbuf += min((physmem_est - 4096) / factor, 430 65536 / factor); 431 if (physmem_est > 65536) 432 nbuf += (physmem_est - 65536) * 2 / (factor * 5); 433 434 if (maxbcache && nbuf > maxbcache / BKVASIZE) 435 nbuf = maxbcache / BKVASIZE; 436 } 437 438 #if 0 439 /* 440 * Do not allow the buffer_map to be more then 1/2 the size of the 441 * kernel_map. 442 */ 443 if (nbuf > (kernel_map->max_offset - kernel_map->min_offset) / 444 (BKVASIZE * 2)) { 445 nbuf = (kernel_map->max_offset - kernel_map->min_offset) / 446 (BKVASIZE * 2); 447 printf("Warning: nbufs capped at %d\n", nbuf); 448 } 449 #endif 450 451 /* 452 * swbufs are used as temporary holders for I/O, such as paging I/O. 453 * We have no less then 16 and no more then 256. 454 */ 455 nswbuf = max(min(nbuf/4, 256), 16); 456 457 /* 458 * Reserve space for the buffer cache buffers 459 */ 460 swbuf = (void *)v; 461 v = (caddr_t)(swbuf + nswbuf); 462 buf = (void *)v; 463 v = (caddr_t)(buf + nbuf); 464 465 /* 466 * Calculate the hash table size and reserve space 467 */ 468 for (bufhashmask = 8; bufhashmask < nbuf / 4; bufhashmask <<= 1) 469 ; 470 bufhashtbl = (void *)v; 471 v = (caddr_t)(bufhashtbl + bufhashmask); 472 --bufhashmask; 473 474 return(v); 475 } 476 477 /* Initialize the buffer subsystem. Called before use of any buffers. */ 478 void 479 bufinit(void) 480 { 481 struct buf *bp; 482 int i; 483 484 GIANT_REQUIRED; 485 486 LIST_INIT(&invalhash); 487 mtx_init(&buftimelock, "buftime lock", MTX_DEF); 488 489 for (i = 0; i <= bufhashmask; i++) 490 LIST_INIT(&bufhashtbl[i]); 491 492 /* next, make a null set of free lists */ 493 for (i = 0; i < BUFFER_QUEUES; i++) 494 TAILQ_INIT(&bufqueues[i]); 495 496 /* finally, initialize each buffer header and stick on empty q */ 497 for (i = 0; i < nbuf; i++) { 498 bp = &buf[i]; 499 bzero(bp, sizeof *bp); 500 bp->b_flags = B_INVAL; /* we're just an empty header */ 501 bp->b_dev = NODEV; 502 bp->b_rcred = NOCRED; 503 bp->b_wcred = NOCRED; 504 bp->b_qindex = QUEUE_EMPTY; 505 bp->b_xflags = 0; 506 LIST_INIT(&bp->b_dep); 507 BUF_LOCKINIT(bp); 508 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 509 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 510 } 511 512 /* 513 * maxbufspace is the absolute maximum amount of buffer space we are 514 * allowed to reserve in KVM and in real terms. The absolute maximum 515 * is nominally used by buf_daemon. hibufspace is the nominal maximum 516 * used by most other processes. The differential is required to 517 * ensure that buf_daemon is able to run when other processes might 518 * be blocked waiting for buffer space. 519 * 520 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 521 * this may result in KVM fragmentation which is not handled optimally 522 * by the system. 523 */ 524 maxbufspace = nbuf * BKVASIZE; 525 hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 526 lobufspace = hibufspace - MAXBSIZE; 527 528 lorunningspace = 512 * 1024; 529 hirunningspace = 1024 * 1024; 530 531 /* 532 * Limit the amount of malloc memory since it is wired permanently into 533 * the kernel space. Even though this is accounted for in the buffer 534 * allocation, we don't want the malloced region to grow uncontrolled. 535 * The malloc scheme improves memory utilization significantly on average 536 * (small) directories. 537 */ 538 maxbufmallocspace = hibufspace / 20; 539 540 /* 541 * Reduce the chance of a deadlock occuring by limiting the number 542 * of delayed-write dirty buffers we allow to stack up. 543 */ 544 hidirtybuffers = nbuf / 4 + 20; 545 numdirtybuffers = 0; 546 /* 547 * To support extreme low-memory systems, make sure hidirtybuffers cannot 548 * eat up all available buffer space. This occurs when our minimum cannot 549 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 550 * BKVASIZE'd (8K) buffers. 551 */ 552 while (hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 553 hidirtybuffers >>= 1; 554 } 555 lodirtybuffers = hidirtybuffers / 2; 556 557 /* 558 * Try to keep the number of free buffers in the specified range, 559 * and give special processes (e.g. like buf_daemon) access to an 560 * emergency reserve. 561 */ 562 lofreebuffers = nbuf / 18 + 5; 563 hifreebuffers = 2 * lofreebuffers; 564 numfreebuffers = nbuf; 565 566 /* 567 * Maximum number of async ops initiated per buf_daemon loop. This is 568 * somewhat of a hack at the moment, we really need to limit ourselves 569 * based on the number of bytes of I/O in-transit that were initiated 570 * from buf_daemon. 571 */ 572 573 bogus_offset = kmem_alloc_pageable(kernel_map, PAGE_SIZE); 574 bogus_page = vm_page_alloc(kernel_object, 575 ((bogus_offset - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 576 VM_ALLOC_NORMAL); 577 cnt.v_wire_count++; 578 } 579 580 /* 581 * bfreekva() - free the kva allocation for a buffer. 582 * 583 * Must be called at splbio() or higher as this is the only locking for 584 * buffer_map. 585 * 586 * Since this call frees up buffer space, we call bufspacewakeup(). 587 */ 588 static void 589 bfreekva(struct buf * bp) 590 { 591 GIANT_REQUIRED; 592 593 if (bp->b_kvasize) { 594 ++buffreekvacnt; 595 bufspace -= bp->b_kvasize; 596 vm_map_delete(buffer_map, 597 (vm_offset_t) bp->b_kvabase, 598 (vm_offset_t) bp->b_kvabase + bp->b_kvasize 599 ); 600 bp->b_kvasize = 0; 601 bufspacewakeup(); 602 } 603 } 604 605 /* 606 * bremfree: 607 * 608 * Remove the buffer from the appropriate free list. 609 */ 610 void 611 bremfree(struct buf * bp) 612 { 613 int s = splbio(); 614 int old_qindex = bp->b_qindex; 615 616 GIANT_REQUIRED; 617 618 if (bp->b_qindex != QUEUE_NONE) { 619 KASSERT(BUF_REFCNT(bp) == 1, ("bremfree: bp %p not locked",bp)); 620 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 621 bp->b_qindex = QUEUE_NONE; 622 } else { 623 if (BUF_REFCNT(bp) <= 1) 624 panic("bremfree: removing a buffer not on a queue"); 625 } 626 627 /* 628 * Fixup numfreebuffers count. If the buffer is invalid or not 629 * delayed-write, and it was on the EMPTY, LRU, or AGE queues, 630 * the buffer was free and we must decrement numfreebuffers. 631 */ 632 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { 633 switch(old_qindex) { 634 case QUEUE_DIRTY: 635 case QUEUE_CLEAN: 636 case QUEUE_EMPTY: 637 case QUEUE_EMPTYKVA: 638 --numfreebuffers; 639 break; 640 default: 641 break; 642 } 643 } 644 splx(s); 645 } 646 647 648 /* 649 * Get a buffer with the specified data. Look in the cache first. We 650 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 651 * is set, the buffer is valid and we do not have to do anything ( see 652 * getblk() ). This is really just a special case of breadn(). 653 */ 654 int 655 bread(struct vnode * vp, daddr_t blkno, int size, struct ucred * cred, 656 struct buf ** bpp) 657 { 658 659 return (breadn(vp, blkno, size, 0, 0, 0, cred, bpp)); 660 } 661 662 /* 663 * Operates like bread, but also starts asynchronous I/O on 664 * read-ahead blocks. We must clear BIO_ERROR and B_INVAL prior 665 * to initiating I/O . If B_CACHE is set, the buffer is valid 666 * and we do not have to do anything. 667 */ 668 int 669 breadn(struct vnode * vp, daddr_t blkno, int size, 670 daddr_t * rablkno, int *rabsize, 671 int cnt, struct ucred * cred, struct buf ** bpp) 672 { 673 struct buf *bp, *rabp; 674 int i; 675 int rv = 0, readwait = 0; 676 677 *bpp = bp = getblk(vp, blkno, size, 0, 0); 678 679 /* if not found in cache, do some I/O */ 680 if ((bp->b_flags & B_CACHE) == 0) { 681 if (curthread != PCPU_GET(idlethread)) 682 curthread->td_proc->p_stats->p_ru.ru_inblock++; 683 bp->b_iocmd = BIO_READ; 684 bp->b_flags &= ~B_INVAL; 685 bp->b_ioflags &= ~BIO_ERROR; 686 if (bp->b_rcred == NOCRED && cred != NOCRED) 687 bp->b_rcred = crhold(cred); 688 vfs_busy_pages(bp, 0); 689 VOP_STRATEGY(vp, bp); 690 ++readwait; 691 } 692 693 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 694 if (inmem(vp, *rablkno)) 695 continue; 696 rabp = getblk(vp, *rablkno, *rabsize, 0, 0); 697 698 if ((rabp->b_flags & B_CACHE) == 0) { 699 if (curthread != PCPU_GET(idlethread)) 700 curthread->td_proc->p_stats->p_ru.ru_inblock++; 701 rabp->b_flags |= B_ASYNC; 702 rabp->b_flags &= ~B_INVAL; 703 rabp->b_ioflags &= ~BIO_ERROR; 704 rabp->b_iocmd = BIO_READ; 705 if (rabp->b_rcred == NOCRED && cred != NOCRED) 706 rabp->b_rcred = crhold(cred); 707 vfs_busy_pages(rabp, 0); 708 BUF_KERNPROC(rabp); 709 VOP_STRATEGY(vp, rabp); 710 } else { 711 brelse(rabp); 712 } 713 } 714 715 if (readwait) { 716 rv = bufwait(bp); 717 } 718 return (rv); 719 } 720 721 /* 722 * Write, release buffer on completion. (Done by iodone 723 * if async). Do not bother writing anything if the buffer 724 * is invalid. 725 * 726 * Note that we set B_CACHE here, indicating that buffer is 727 * fully valid and thus cacheable. This is true even of NFS 728 * now so we set it generally. This could be set either here 729 * or in biodone() since the I/O is synchronous. We put it 730 * here. 731 */ 732 733 int 734 bwrite(struct buf * bp) 735 { 736 int oldflags, s; 737 struct buf *newbp; 738 739 if (bp->b_flags & B_INVAL) { 740 brelse(bp); 741 return (0); 742 } 743 744 oldflags = bp->b_flags; 745 746 if (BUF_REFCNT(bp) == 0) 747 panic("bwrite: buffer is not busy???"); 748 s = splbio(); 749 /* 750 * If a background write is already in progress, delay 751 * writing this block if it is asynchronous. Otherwise 752 * wait for the background write to complete. 753 */ 754 if (bp->b_xflags & BX_BKGRDINPROG) { 755 if (bp->b_flags & B_ASYNC) { 756 splx(s); 757 bdwrite(bp); 758 return (0); 759 } 760 bp->b_xflags |= BX_BKGRDWAIT; 761 tsleep(&bp->b_xflags, PRIBIO, "biord", 0); 762 if (bp->b_xflags & BX_BKGRDINPROG) 763 panic("bwrite: still writing"); 764 } 765 766 /* Mark the buffer clean */ 767 bundirty(bp); 768 769 /* 770 * If this buffer is marked for background writing and we 771 * do not have to wait for it, make a copy and write the 772 * copy so as to leave this buffer ready for further use. 773 * 774 * This optimization eats a lot of memory. If we have a page 775 * or buffer shortfall we can't do it. 776 */ 777 if (dobkgrdwrite && (bp->b_xflags & BX_BKGRDWRITE) && 778 (bp->b_flags & B_ASYNC) && 779 !vm_page_count_severe() && 780 !buf_dirty_count_severe()) { 781 if (bp->b_iodone != NULL) { 782 printf("bp->b_iodone = %p\n", bp->b_iodone); 783 panic("bwrite: need chained iodone"); 784 } 785 786 /* get a new block */ 787 newbp = geteblk(bp->b_bufsize); 788 789 /* set it to be identical to the old block */ 790 memcpy(newbp->b_data, bp->b_data, bp->b_bufsize); 791 bgetvp(bp->b_vp, newbp); 792 newbp->b_lblkno = bp->b_lblkno; 793 newbp->b_blkno = bp->b_blkno; 794 newbp->b_offset = bp->b_offset; 795 newbp->b_iodone = vfs_backgroundwritedone; 796 newbp->b_flags |= B_ASYNC; 797 newbp->b_flags &= ~B_INVAL; 798 799 /* move over the dependencies */ 800 if (LIST_FIRST(&bp->b_dep) != NULL) 801 buf_movedeps(bp, newbp); 802 803 /* 804 * Initiate write on the copy, release the original to 805 * the B_LOCKED queue so that it cannot go away until 806 * the background write completes. If not locked it could go 807 * away and then be reconstituted while it was being written. 808 * If the reconstituted buffer were written, we could end up 809 * with two background copies being written at the same time. 810 */ 811 bp->b_xflags |= BX_BKGRDINPROG; 812 bp->b_flags |= B_LOCKED; 813 bqrelse(bp); 814 bp = newbp; 815 } 816 817 bp->b_flags &= ~B_DONE; 818 bp->b_ioflags &= ~BIO_ERROR; 819 bp->b_flags |= B_WRITEINPROG | B_CACHE; 820 bp->b_iocmd = BIO_WRITE; 821 822 bp->b_vp->v_numoutput++; 823 vfs_busy_pages(bp, 1); 824 825 /* 826 * Normal bwrites pipeline writes 827 */ 828 bp->b_runningbufspace = bp->b_bufsize; 829 runningbufspace += bp->b_runningbufspace; 830 831 if (curthread != PCPU_GET(idlethread)) 832 curthread->td_proc->p_stats->p_ru.ru_oublock++; 833 splx(s); 834 if (oldflags & B_ASYNC) 835 BUF_KERNPROC(bp); 836 BUF_STRATEGY(bp); 837 838 if ((oldflags & B_ASYNC) == 0) { 839 int rtval = bufwait(bp); 840 brelse(bp); 841 return (rtval); 842 } else if ((oldflags & B_NOWDRAIN) == 0) { 843 /* 844 * don't allow the async write to saturate the I/O 845 * system. Deadlocks can occur only if a device strategy 846 * routine (like in MD) turns around and issues another 847 * high-level write, in which case B_NOWDRAIN is expected 848 * to be set. Otherwise we will not deadlock here because 849 * we are blocking waiting for I/O that is already in-progress 850 * to complete. 851 */ 852 waitrunningbufspace(); 853 } 854 855 return (0); 856 } 857 858 /* 859 * Complete a background write started from bwrite. 860 */ 861 static void 862 vfs_backgroundwritedone(bp) 863 struct buf *bp; 864 { 865 struct buf *origbp; 866 867 /* 868 * Find the original buffer that we are writing. 869 */ 870 if ((origbp = gbincore(bp->b_vp, bp->b_lblkno)) == NULL) 871 panic("backgroundwritedone: lost buffer"); 872 /* 873 * Process dependencies then return any unfinished ones. 874 */ 875 if (LIST_FIRST(&bp->b_dep) != NULL) 876 buf_complete(bp); 877 if (LIST_FIRST(&bp->b_dep) != NULL) 878 buf_movedeps(bp, origbp); 879 /* 880 * Clear the BX_BKGRDINPROG flag in the original buffer 881 * and awaken it if it is waiting for the write to complete. 882 * If BX_BKGRDINPROG is not set in the original buffer it must 883 * have been released and re-instantiated - which is not legal. 884 */ 885 KASSERT((origbp->b_xflags & BX_BKGRDINPROG), 886 ("backgroundwritedone: lost buffer2")); 887 origbp->b_xflags &= ~BX_BKGRDINPROG; 888 if (origbp->b_xflags & BX_BKGRDWAIT) { 889 origbp->b_xflags &= ~BX_BKGRDWAIT; 890 wakeup(&origbp->b_xflags); 891 } 892 /* 893 * Clear the B_LOCKED flag and remove it from the locked 894 * queue if it currently resides there. 895 */ 896 origbp->b_flags &= ~B_LOCKED; 897 if (BUF_LOCK(origbp, LK_EXCLUSIVE | LK_NOWAIT) == 0) { 898 bremfree(origbp); 899 bqrelse(origbp); 900 } 901 /* 902 * This buffer is marked B_NOCACHE, so when it is released 903 * by biodone, it will be tossed. We mark it with BIO_READ 904 * to avoid biodone doing a second vwakeup. 905 */ 906 bp->b_flags |= B_NOCACHE; 907 bp->b_iocmd = BIO_READ; 908 bp->b_flags &= ~(B_CACHE | B_DONE); 909 bp->b_iodone = 0; 910 bufdone(bp); 911 } 912 913 /* 914 * Delayed write. (Buffer is marked dirty). Do not bother writing 915 * anything if the buffer is marked invalid. 916 * 917 * Note that since the buffer must be completely valid, we can safely 918 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 919 * biodone() in order to prevent getblk from writing the buffer 920 * out synchronously. 921 */ 922 void 923 bdwrite(struct buf * bp) 924 { 925 GIANT_REQUIRED; 926 927 if (BUF_REFCNT(bp) == 0) 928 panic("bdwrite: buffer is not busy"); 929 930 if (bp->b_flags & B_INVAL) { 931 brelse(bp); 932 return; 933 } 934 bdirty(bp); 935 936 /* 937 * Set B_CACHE, indicating that the buffer is fully valid. This is 938 * true even of NFS now. 939 */ 940 bp->b_flags |= B_CACHE; 941 942 /* 943 * This bmap keeps the system from needing to do the bmap later, 944 * perhaps when the system is attempting to do a sync. Since it 945 * is likely that the indirect block -- or whatever other datastructure 946 * that the filesystem needs is still in memory now, it is a good 947 * thing to do this. Note also, that if the pageout daemon is 948 * requesting a sync -- there might not be enough memory to do 949 * the bmap then... So, this is important to do. 950 */ 951 if (bp->b_lblkno == bp->b_blkno) { 952 VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 953 } 954 955 /* 956 * Set the *dirty* buffer range based upon the VM system dirty pages. 957 */ 958 vfs_setdirty(bp); 959 960 /* 961 * We need to do this here to satisfy the vnode_pager and the 962 * pageout daemon, so that it thinks that the pages have been 963 * "cleaned". Note that since the pages are in a delayed write 964 * buffer -- the VFS layer "will" see that the pages get written 965 * out on the next sync, or perhaps the cluster will be completed. 966 */ 967 vfs_clean_pages(bp); 968 bqrelse(bp); 969 970 /* 971 * Wakeup the buffer flushing daemon if we have a lot of dirty 972 * buffers (midpoint between our recovery point and our stall 973 * point). 974 */ 975 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 976 977 /* 978 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 979 * due to the softdep code. 980 */ 981 } 982 983 /* 984 * bdirty: 985 * 986 * Turn buffer into delayed write request. We must clear BIO_READ and 987 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 988 * itself to properly update it in the dirty/clean lists. We mark it 989 * B_DONE to ensure that any asynchronization of the buffer properly 990 * clears B_DONE ( else a panic will occur later ). 991 * 992 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 993 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 994 * should only be called if the buffer is known-good. 995 * 996 * Since the buffer is not on a queue, we do not update the numfreebuffers 997 * count. 998 * 999 * Must be called at splbio(). 1000 * The buffer must be on QUEUE_NONE. 1001 */ 1002 void 1003 bdirty(bp) 1004 struct buf *bp; 1005 { 1006 KASSERT(bp->b_qindex == QUEUE_NONE, 1007 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1008 bp->b_flags &= ~(B_RELBUF); 1009 bp->b_iocmd = BIO_WRITE; 1010 1011 if ((bp->b_flags & B_DELWRI) == 0) { 1012 bp->b_flags |= B_DONE | B_DELWRI; 1013 reassignbuf(bp, bp->b_vp); 1014 ++numdirtybuffers; 1015 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 1016 } 1017 } 1018 1019 /* 1020 * bundirty: 1021 * 1022 * Clear B_DELWRI for buffer. 1023 * 1024 * Since the buffer is not on a queue, we do not update the numfreebuffers 1025 * count. 1026 * 1027 * Must be called at splbio(). 1028 * The buffer must be on QUEUE_NONE. 1029 */ 1030 1031 void 1032 bundirty(bp) 1033 struct buf *bp; 1034 { 1035 KASSERT(bp->b_qindex == QUEUE_NONE, 1036 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1037 1038 if (bp->b_flags & B_DELWRI) { 1039 bp->b_flags &= ~B_DELWRI; 1040 reassignbuf(bp, bp->b_vp); 1041 --numdirtybuffers; 1042 numdirtywakeup(lodirtybuffers); 1043 } 1044 /* 1045 * Since it is now being written, we can clear its deferred write flag. 1046 */ 1047 bp->b_flags &= ~B_DEFERRED; 1048 } 1049 1050 /* 1051 * bawrite: 1052 * 1053 * Asynchronous write. Start output on a buffer, but do not wait for 1054 * it to complete. The buffer is released when the output completes. 1055 * 1056 * bwrite() ( or the VOP routine anyway ) is responsible for handling 1057 * B_INVAL buffers. Not us. 1058 */ 1059 void 1060 bawrite(struct buf * bp) 1061 { 1062 bp->b_flags |= B_ASYNC; 1063 (void) BUF_WRITE(bp); 1064 } 1065 1066 /* 1067 * bwillwrite: 1068 * 1069 * Called prior to the locking of any vnodes when we are expecting to 1070 * write. We do not want to starve the buffer cache with too many 1071 * dirty buffers so we block here. By blocking prior to the locking 1072 * of any vnodes we attempt to avoid the situation where a locked vnode 1073 * prevents the various system daemons from flushing related buffers. 1074 */ 1075 1076 void 1077 bwillwrite(void) 1078 { 1079 if (numdirtybuffers >= hidirtybuffers) { 1080 int s; 1081 1082 mtx_lock(&Giant); 1083 s = splbio(); 1084 while (numdirtybuffers >= hidirtybuffers) { 1085 bd_wakeup(1); 1086 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH; 1087 tsleep(&needsbuffer, (PRIBIO + 4), "flswai", 0); 1088 } 1089 splx(s); 1090 mtx_unlock(&Giant); 1091 } 1092 } 1093 1094 /* 1095 * Return true if we have too many dirty buffers. 1096 */ 1097 int 1098 buf_dirty_count_severe(void) 1099 { 1100 return(numdirtybuffers >= hidirtybuffers); 1101 } 1102 1103 /* 1104 * brelse: 1105 * 1106 * Release a busy buffer and, if requested, free its resources. The 1107 * buffer will be stashed in the appropriate bufqueue[] allowing it 1108 * to be accessed later as a cache entity or reused for other purposes. 1109 */ 1110 void 1111 brelse(struct buf * bp) 1112 { 1113 int s; 1114 1115 GIANT_REQUIRED; 1116 1117 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1118 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1119 1120 s = splbio(); 1121 1122 if (bp->b_flags & B_LOCKED) 1123 bp->b_ioflags &= ~BIO_ERROR; 1124 1125 if (bp->b_iocmd == BIO_WRITE && 1126 (bp->b_ioflags & BIO_ERROR) && 1127 !(bp->b_flags & B_INVAL)) { 1128 /* 1129 * Failed write, redirty. Must clear BIO_ERROR to prevent 1130 * pages from being scrapped. If B_INVAL is set then 1131 * this case is not run and the next case is run to 1132 * destroy the buffer. B_INVAL can occur if the buffer 1133 * is outside the range supported by the underlying device. 1134 */ 1135 bp->b_ioflags &= ~BIO_ERROR; 1136 bdirty(bp); 1137 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 1138 (bp->b_ioflags & BIO_ERROR) || 1139 bp->b_iocmd == BIO_DELETE || (bp->b_bufsize <= 0)) { 1140 /* 1141 * Either a failed I/O or we were asked to free or not 1142 * cache the buffer. 1143 */ 1144 bp->b_flags |= B_INVAL; 1145 if (LIST_FIRST(&bp->b_dep) != NULL) 1146 buf_deallocate(bp); 1147 if (bp->b_flags & B_DELWRI) { 1148 --numdirtybuffers; 1149 numdirtywakeup(lodirtybuffers); 1150 } 1151 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1152 if ((bp->b_flags & B_VMIO) == 0) { 1153 if (bp->b_bufsize) 1154 allocbuf(bp, 0); 1155 if (bp->b_vp) 1156 brelvp(bp); 1157 } 1158 } 1159 1160 /* 1161 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1162 * is called with B_DELWRI set, the underlying pages may wind up 1163 * getting freed causing a previous write (bdwrite()) to get 'lost' 1164 * because pages associated with a B_DELWRI bp are marked clean. 1165 * 1166 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1167 * if B_DELWRI is set. 1168 * 1169 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1170 * on pages to return pages to the VM page queues. 1171 */ 1172 if (bp->b_flags & B_DELWRI) 1173 bp->b_flags &= ~B_RELBUF; 1174 else if (vm_page_count_severe() && !(bp->b_xflags & BX_BKGRDINPROG)) 1175 bp->b_flags |= B_RELBUF; 1176 1177 /* 1178 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1179 * constituted, not even NFS buffers now. Two flags effect this. If 1180 * B_INVAL, the struct buf is invalidated but the VM object is kept 1181 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1182 * 1183 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 1184 * invalidated. BIO_ERROR cannot be set for a failed write unless the 1185 * buffer is also B_INVAL because it hits the re-dirtying code above. 1186 * 1187 * Normally we can do this whether a buffer is B_DELWRI or not. If 1188 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1189 * the commit state and we cannot afford to lose the buffer. If the 1190 * buffer has a background write in progress, we need to keep it 1191 * around to prevent it from being reconstituted and starting a second 1192 * background write. 1193 */ 1194 if ((bp->b_flags & B_VMIO) 1195 && !(bp->b_vp->v_tag == VT_NFS && 1196 !vn_isdisk(bp->b_vp, NULL) && 1197 (bp->b_flags & B_DELWRI)) 1198 ) { 1199 1200 int i, j, resid; 1201 vm_page_t m; 1202 off_t foff; 1203 vm_pindex_t poff; 1204 vm_object_t obj; 1205 struct vnode *vp; 1206 1207 vp = bp->b_vp; 1208 1209 /* 1210 * Get the base offset and length of the buffer. Note that 1211 * in the VMIO case if the buffer block size is not 1212 * page-aligned then b_data pointer may not be page-aligned. 1213 * But our b_pages[] array *IS* page aligned. 1214 * 1215 * block sizes less then DEV_BSIZE (usually 512) are not 1216 * supported due to the page granularity bits (m->valid, 1217 * m->dirty, etc...). 1218 * 1219 * See man buf(9) for more information 1220 */ 1221 resid = bp->b_bufsize; 1222 foff = bp->b_offset; 1223 1224 for (i = 0; i < bp->b_npages; i++) { 1225 int had_bogus = 0; 1226 1227 m = bp->b_pages[i]; 1228 vm_page_flag_clear(m, PG_ZERO); 1229 1230 /* 1231 * If we hit a bogus page, fixup *all* the bogus pages 1232 * now. 1233 */ 1234 if (m == bogus_page) { 1235 VOP_GETVOBJECT(vp, &obj); 1236 poff = OFF_TO_IDX(bp->b_offset); 1237 had_bogus = 1; 1238 1239 for (j = i; j < bp->b_npages; j++) { 1240 vm_page_t mtmp; 1241 mtmp = bp->b_pages[j]; 1242 if (mtmp == bogus_page) { 1243 mtmp = vm_page_lookup(obj, poff + j); 1244 if (!mtmp) { 1245 panic("brelse: page missing\n"); 1246 } 1247 bp->b_pages[j] = mtmp; 1248 } 1249 } 1250 1251 if ((bp->b_flags & B_INVAL) == 0) { 1252 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 1253 } 1254 m = bp->b_pages[i]; 1255 } 1256 if ((bp->b_flags & B_NOCACHE) || (bp->b_ioflags & BIO_ERROR)) { 1257 int poffset = foff & PAGE_MASK; 1258 int presid = resid > (PAGE_SIZE - poffset) ? 1259 (PAGE_SIZE - poffset) : resid; 1260 1261 KASSERT(presid >= 0, ("brelse: extra page")); 1262 vm_page_set_invalid(m, poffset, presid); 1263 if (had_bogus) 1264 printf("avoided corruption bug in bogus_page/brelse code\n"); 1265 } 1266 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1267 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1268 } 1269 1270 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1271 vfs_vmio_release(bp); 1272 1273 } else if (bp->b_flags & B_VMIO) { 1274 1275 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1276 vfs_vmio_release(bp); 1277 } 1278 1279 } 1280 1281 if (bp->b_qindex != QUEUE_NONE) 1282 panic("brelse: free buffer onto another queue???"); 1283 if (BUF_REFCNT(bp) > 1) { 1284 /* do not release to free list */ 1285 BUF_UNLOCK(bp); 1286 splx(s); 1287 return; 1288 } 1289 1290 /* enqueue */ 1291 1292 /* buffers with no memory */ 1293 if (bp->b_bufsize == 0) { 1294 bp->b_flags |= B_INVAL; 1295 bp->b_xflags &= ~BX_BKGRDWRITE; 1296 if (bp->b_xflags & BX_BKGRDINPROG) 1297 panic("losing buffer 1"); 1298 if (bp->b_kvasize) { 1299 bp->b_qindex = QUEUE_EMPTYKVA; 1300 } else { 1301 bp->b_qindex = QUEUE_EMPTY; 1302 } 1303 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1304 LIST_REMOVE(bp, b_hash); 1305 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1306 bp->b_dev = NODEV; 1307 /* buffers with junk contents */ 1308 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 1309 (bp->b_ioflags & BIO_ERROR)) { 1310 bp->b_flags |= B_INVAL; 1311 bp->b_xflags &= ~BX_BKGRDWRITE; 1312 if (bp->b_xflags & BX_BKGRDINPROG) 1313 panic("losing buffer 2"); 1314 bp->b_qindex = QUEUE_CLEAN; 1315 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1316 LIST_REMOVE(bp, b_hash); 1317 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1318 bp->b_dev = NODEV; 1319 1320 /* buffers that are locked */ 1321 } else if (bp->b_flags & B_LOCKED) { 1322 bp->b_qindex = QUEUE_LOCKED; 1323 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LOCKED], bp, b_freelist); 1324 1325 /* remaining buffers */ 1326 } else { 1327 if (bp->b_flags & B_DELWRI) 1328 bp->b_qindex = QUEUE_DIRTY; 1329 else 1330 bp->b_qindex = QUEUE_CLEAN; 1331 if (bp->b_flags & B_AGE) 1332 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1333 else 1334 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1335 } 1336 1337 /* 1338 * If B_INVAL, clear B_DELWRI. We've already placed the buffer 1339 * on the correct queue. 1340 */ 1341 if ((bp->b_flags & (B_INVAL|B_DELWRI)) == (B_INVAL|B_DELWRI)) { 1342 bp->b_flags &= ~B_DELWRI; 1343 --numdirtybuffers; 1344 numdirtywakeup(lodirtybuffers); 1345 } 1346 1347 /* 1348 * Fixup numfreebuffers count. The bp is on an appropriate queue 1349 * unless locked. We then bump numfreebuffers if it is not B_DELWRI. 1350 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1351 * if B_INVAL is set ). 1352 */ 1353 1354 if ((bp->b_flags & B_LOCKED) == 0 && !(bp->b_flags & B_DELWRI)) 1355 bufcountwakeup(); 1356 1357 /* 1358 * Something we can maybe free or reuse 1359 */ 1360 if (bp->b_bufsize || bp->b_kvasize) 1361 bufspacewakeup(); 1362 1363 /* unlock */ 1364 BUF_UNLOCK(bp); 1365 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | 1366 B_DIRECT | B_NOWDRAIN); 1367 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1368 panic("brelse: not dirty"); 1369 splx(s); 1370 } 1371 1372 /* 1373 * Release a buffer back to the appropriate queue but do not try to free 1374 * it. The buffer is expected to be used again soon. 1375 * 1376 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1377 * biodone() to requeue an async I/O on completion. It is also used when 1378 * known good buffers need to be requeued but we think we may need the data 1379 * again soon. 1380 * 1381 * XXX we should be able to leave the B_RELBUF hint set on completion. 1382 */ 1383 void 1384 bqrelse(struct buf * bp) 1385 { 1386 int s; 1387 1388 s = splbio(); 1389 1390 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1391 1392 if (bp->b_qindex != QUEUE_NONE) 1393 panic("bqrelse: free buffer onto another queue???"); 1394 if (BUF_REFCNT(bp) > 1) { 1395 /* do not release to free list */ 1396 BUF_UNLOCK(bp); 1397 splx(s); 1398 return; 1399 } 1400 if (bp->b_flags & B_LOCKED) { 1401 bp->b_ioflags &= ~BIO_ERROR; 1402 bp->b_qindex = QUEUE_LOCKED; 1403 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LOCKED], bp, b_freelist); 1404 /* buffers with stale but valid contents */ 1405 } else if (bp->b_flags & B_DELWRI) { 1406 bp->b_qindex = QUEUE_DIRTY; 1407 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist); 1408 } else if (vm_page_count_severe()) { 1409 /* 1410 * We are too low on memory, we have to try to free the 1411 * buffer (most importantly: the wired pages making up its 1412 * backing store) *now*. 1413 */ 1414 splx(s); 1415 brelse(bp); 1416 return; 1417 } else { 1418 bp->b_qindex = QUEUE_CLEAN; 1419 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1420 } 1421 1422 if ((bp->b_flags & B_LOCKED) == 0 && 1423 ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI))) { 1424 bufcountwakeup(); 1425 } 1426 1427 /* 1428 * Something we can maybe free or reuse. 1429 */ 1430 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1431 bufspacewakeup(); 1432 1433 /* unlock */ 1434 BUF_UNLOCK(bp); 1435 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1436 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1437 panic("bqrelse: not dirty"); 1438 splx(s); 1439 } 1440 1441 /* Give pages used by the bp back to the VM system (where possible) */ 1442 static void 1443 vfs_vmio_release(bp) 1444 struct buf *bp; 1445 { 1446 int i; 1447 vm_page_t m; 1448 1449 GIANT_REQUIRED; 1450 1451 for (i = 0; i < bp->b_npages; i++) { 1452 m = bp->b_pages[i]; 1453 bp->b_pages[i] = NULL; 1454 /* 1455 * In order to keep page LRU ordering consistent, put 1456 * everything on the inactive queue. 1457 */ 1458 vm_page_unwire(m, 0); 1459 /* 1460 * We don't mess with busy pages, it is 1461 * the responsibility of the process that 1462 * busied the pages to deal with them. 1463 */ 1464 if ((m->flags & PG_BUSY) || (m->busy != 0)) 1465 continue; 1466 1467 if (m->wire_count == 0) { 1468 vm_page_flag_clear(m, PG_ZERO); 1469 /* 1470 * Might as well free the page if we can and it has 1471 * no valid data. We also free the page if the 1472 * buffer was used for direct I/O 1473 */ 1474 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && 1475 m->hold_count == 0) { 1476 vm_page_busy(m); 1477 vm_page_protect(m, VM_PROT_NONE); 1478 vm_page_free(m); 1479 } else if (bp->b_flags & B_DIRECT) { 1480 vm_page_try_to_free(m); 1481 } else if (vm_page_count_severe()) { 1482 vm_page_try_to_cache(m); 1483 } 1484 } 1485 } 1486 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages); 1487 1488 if (bp->b_bufsize) { 1489 bufspacewakeup(); 1490 bp->b_bufsize = 0; 1491 } 1492 bp->b_npages = 0; 1493 bp->b_flags &= ~B_VMIO; 1494 if (bp->b_vp) 1495 brelvp(bp); 1496 } 1497 1498 /* 1499 * Check to see if a block is currently memory resident. 1500 */ 1501 struct buf * 1502 gbincore(struct vnode * vp, daddr_t blkno) 1503 { 1504 struct buf *bp; 1505 struct bufhashhdr *bh; 1506 1507 bh = bufhash(vp, blkno); 1508 1509 /* Search hash chain */ 1510 LIST_FOREACH(bp, bh, b_hash) { 1511 /* hit */ 1512 if (bp->b_vp == vp && bp->b_lblkno == blkno && 1513 (bp->b_flags & B_INVAL) == 0) { 1514 break; 1515 } 1516 } 1517 return (bp); 1518 } 1519 1520 /* 1521 * vfs_bio_awrite: 1522 * 1523 * Implement clustered async writes for clearing out B_DELWRI buffers. 1524 * This is much better then the old way of writing only one buffer at 1525 * a time. Note that we may not be presented with the buffers in the 1526 * correct order, so we search for the cluster in both directions. 1527 */ 1528 int 1529 vfs_bio_awrite(struct buf * bp) 1530 { 1531 int i; 1532 int j; 1533 daddr_t lblkno = bp->b_lblkno; 1534 struct vnode *vp = bp->b_vp; 1535 int s; 1536 int ncl; 1537 struct buf *bpa; 1538 int nwritten; 1539 int size; 1540 int maxcl; 1541 1542 s = splbio(); 1543 /* 1544 * right now we support clustered writing only to regular files. If 1545 * we find a clusterable block we could be in the middle of a cluster 1546 * rather then at the beginning. 1547 */ 1548 if ((vp->v_type == VREG) && 1549 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1550 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1551 1552 size = vp->v_mount->mnt_stat.f_iosize; 1553 maxcl = MAXPHYS / size; 1554 1555 for (i = 1; i < maxcl; i++) { 1556 if ((bpa = gbincore(vp, lblkno + i)) && 1557 BUF_REFCNT(bpa) == 0 && 1558 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == 1559 (B_DELWRI | B_CLUSTEROK)) && 1560 (bpa->b_bufsize == size)) { 1561 if ((bpa->b_blkno == bpa->b_lblkno) || 1562 (bpa->b_blkno != 1563 bp->b_blkno + ((i * size) >> DEV_BSHIFT))) 1564 break; 1565 } else { 1566 break; 1567 } 1568 } 1569 for (j = 1; i + j <= maxcl && j <= lblkno; j++) { 1570 if ((bpa = gbincore(vp, lblkno - j)) && 1571 BUF_REFCNT(bpa) == 0 && 1572 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == 1573 (B_DELWRI | B_CLUSTEROK)) && 1574 (bpa->b_bufsize == size)) { 1575 if ((bpa->b_blkno == bpa->b_lblkno) || 1576 (bpa->b_blkno != 1577 bp->b_blkno - ((j * size) >> DEV_BSHIFT))) 1578 break; 1579 } else { 1580 break; 1581 } 1582 } 1583 --j; 1584 ncl = i + j; 1585 /* 1586 * this is a possible cluster write 1587 */ 1588 if (ncl != 1) { 1589 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl); 1590 splx(s); 1591 return nwritten; 1592 } 1593 } 1594 1595 BUF_LOCK(bp, LK_EXCLUSIVE); 1596 bremfree(bp); 1597 bp->b_flags |= B_ASYNC; 1598 1599 splx(s); 1600 /* 1601 * default (old) behavior, writing out only one block 1602 * 1603 * XXX returns b_bufsize instead of b_bcount for nwritten? 1604 */ 1605 nwritten = bp->b_bufsize; 1606 (void) BUF_WRITE(bp); 1607 1608 return nwritten; 1609 } 1610 1611 /* 1612 * getnewbuf: 1613 * 1614 * Find and initialize a new buffer header, freeing up existing buffers 1615 * in the bufqueues as necessary. The new buffer is returned locked. 1616 * 1617 * Important: B_INVAL is not set. If the caller wishes to throw the 1618 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1619 * 1620 * We block if: 1621 * We have insufficient buffer headers 1622 * We have insufficient buffer space 1623 * buffer_map is too fragmented ( space reservation fails ) 1624 * If we have to flush dirty buffers ( but we try to avoid this ) 1625 * 1626 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1627 * Instead we ask the buf daemon to do it for us. We attempt to 1628 * avoid piecemeal wakeups of the pageout daemon. 1629 */ 1630 1631 static struct buf * 1632 getnewbuf(int slpflag, int slptimeo, int size, int maxsize) 1633 { 1634 struct buf *bp; 1635 struct buf *nbp; 1636 int defrag = 0; 1637 int nqindex; 1638 static int flushingbufs; 1639 1640 GIANT_REQUIRED; 1641 1642 /* 1643 * We can't afford to block since we might be holding a vnode lock, 1644 * which may prevent system daemons from running. We deal with 1645 * low-memory situations by proactively returning memory and running 1646 * async I/O rather then sync I/O. 1647 */ 1648 1649 ++getnewbufcalls; 1650 --getnewbufrestarts; 1651 restart: 1652 ++getnewbufrestarts; 1653 1654 /* 1655 * Setup for scan. If we do not have enough free buffers, 1656 * we setup a degenerate case that immediately fails. Note 1657 * that if we are specially marked process, we are allowed to 1658 * dip into our reserves. 1659 * 1660 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 1661 * 1662 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 1663 * However, there are a number of cases (defragging, reusing, ...) 1664 * where we cannot backup. 1665 */ 1666 nqindex = QUEUE_EMPTYKVA; 1667 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 1668 1669 if (nbp == NULL) { 1670 /* 1671 * If no EMPTYKVA buffers and we are either 1672 * defragging or reusing, locate a CLEAN buffer 1673 * to free or reuse. If bufspace useage is low 1674 * skip this step so we can allocate a new buffer. 1675 */ 1676 if (defrag || bufspace >= lobufspace) { 1677 nqindex = QUEUE_CLEAN; 1678 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 1679 } 1680 1681 /* 1682 * If we could not find or were not allowed to reuse a 1683 * CLEAN buffer, check to see if it is ok to use an EMPTY 1684 * buffer. We can only use an EMPTY buffer if allocating 1685 * its KVA would not otherwise run us out of buffer space. 1686 */ 1687 if (nbp == NULL && defrag == 0 && 1688 bufspace + maxsize < hibufspace) { 1689 nqindex = QUEUE_EMPTY; 1690 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1691 } 1692 } 1693 1694 /* 1695 * Run scan, possibly freeing data and/or kva mappings on the fly 1696 * depending. 1697 */ 1698 1699 while ((bp = nbp) != NULL) { 1700 int qindex = nqindex; 1701 1702 /* 1703 * Calculate next bp ( we can only use it if we do not block 1704 * or do other fancy things ). 1705 */ 1706 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 1707 switch(qindex) { 1708 case QUEUE_EMPTY: 1709 nqindex = QUEUE_EMPTYKVA; 1710 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]))) 1711 break; 1712 /* fall through */ 1713 case QUEUE_EMPTYKVA: 1714 nqindex = QUEUE_CLEAN; 1715 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]))) 1716 break; 1717 /* fall through */ 1718 case QUEUE_CLEAN: 1719 /* 1720 * nbp is NULL. 1721 */ 1722 break; 1723 } 1724 } 1725 1726 /* 1727 * Sanity Checks 1728 */ 1729 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp)); 1730 1731 /* 1732 * Note: we no longer distinguish between VMIO and non-VMIO 1733 * buffers. 1734 */ 1735 1736 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); 1737 1738 /* 1739 * If we are defragging then we need a buffer with 1740 * b_kvasize != 0. XXX this situation should no longer 1741 * occur, if defrag is non-zero the buffer's b_kvasize 1742 * should also be non-zero at this point. XXX 1743 */ 1744 if (defrag && bp->b_kvasize == 0) { 1745 printf("Warning: defrag empty buffer %p\n", bp); 1746 continue; 1747 } 1748 1749 /* 1750 * Start freeing the bp. This is somewhat involved. nbp 1751 * remains valid only for QUEUE_EMPTY[KVA] bp's. 1752 */ 1753 1754 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) 1755 panic("getnewbuf: locked buf"); 1756 bremfree(bp); 1757 1758 if (qindex == QUEUE_CLEAN) { 1759 if (bp->b_flags & B_VMIO) { 1760 bp->b_flags &= ~B_ASYNC; 1761 vfs_vmio_release(bp); 1762 } 1763 if (bp->b_vp) 1764 brelvp(bp); 1765 } 1766 1767 /* 1768 * NOTE: nbp is now entirely invalid. We can only restart 1769 * the scan from this point on. 1770 * 1771 * Get the rest of the buffer freed up. b_kva* is still 1772 * valid after this operation. 1773 */ 1774 1775 if (bp->b_rcred != NOCRED) { 1776 crfree(bp->b_rcred); 1777 bp->b_rcred = NOCRED; 1778 } 1779 if (bp->b_wcred != NOCRED) { 1780 crfree(bp->b_wcred); 1781 bp->b_wcred = NOCRED; 1782 } 1783 if (LIST_FIRST(&bp->b_dep) != NULL) 1784 buf_deallocate(bp); 1785 if (bp->b_xflags & BX_BKGRDINPROG) 1786 panic("losing buffer 3"); 1787 LIST_REMOVE(bp, b_hash); 1788 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1789 1790 if (bp->b_bufsize) 1791 allocbuf(bp, 0); 1792 1793 bp->b_flags = 0; 1794 bp->b_ioflags = 0; 1795 bp->b_xflags = 0; 1796 bp->b_dev = NODEV; 1797 bp->b_vp = NULL; 1798 bp->b_blkno = bp->b_lblkno = 0; 1799 bp->b_offset = NOOFFSET; 1800 bp->b_iodone = 0; 1801 bp->b_error = 0; 1802 bp->b_resid = 0; 1803 bp->b_bcount = 0; 1804 bp->b_npages = 0; 1805 bp->b_dirtyoff = bp->b_dirtyend = 0; 1806 bp->b_magic = B_MAGIC_BIO; 1807 bp->b_op = &buf_ops_bio; 1808 1809 LIST_INIT(&bp->b_dep); 1810 1811 /* 1812 * If we are defragging then free the buffer. 1813 */ 1814 if (defrag) { 1815 bp->b_flags |= B_INVAL; 1816 bfreekva(bp); 1817 brelse(bp); 1818 defrag = 0; 1819 goto restart; 1820 } 1821 1822 /* 1823 * If we are overcomitted then recover the buffer and its 1824 * KVM space. This occurs in rare situations when multiple 1825 * processes are blocked in getnewbuf() or allocbuf(). 1826 */ 1827 if (bufspace >= hibufspace) 1828 flushingbufs = 1; 1829 if (flushingbufs && bp->b_kvasize != 0) { 1830 bp->b_flags |= B_INVAL; 1831 bfreekva(bp); 1832 brelse(bp); 1833 goto restart; 1834 } 1835 if (bufspace < lobufspace) 1836 flushingbufs = 0; 1837 break; 1838 } 1839 1840 /* 1841 * If we exhausted our list, sleep as appropriate. We may have to 1842 * wakeup various daemons and write out some dirty buffers. 1843 * 1844 * Generally we are sleeping due to insufficient buffer space. 1845 */ 1846 1847 if (bp == NULL) { 1848 int flags; 1849 char *waitmsg; 1850 1851 if (defrag) { 1852 flags = VFS_BIO_NEED_BUFSPACE; 1853 waitmsg = "nbufkv"; 1854 } else if (bufspace >= hibufspace) { 1855 waitmsg = "nbufbs"; 1856 flags = VFS_BIO_NEED_BUFSPACE; 1857 } else { 1858 waitmsg = "newbuf"; 1859 flags = VFS_BIO_NEED_ANY; 1860 } 1861 1862 bd_speedup(); /* heeeelp */ 1863 1864 needsbuffer |= flags; 1865 while (needsbuffer & flags) { 1866 if (tsleep(&needsbuffer, (PRIBIO + 4) | slpflag, 1867 waitmsg, slptimeo)) 1868 return (NULL); 1869 } 1870 } else { 1871 /* 1872 * We finally have a valid bp. We aren't quite out of the 1873 * woods, we still have to reserve kva space. In order 1874 * to keep fragmentation sane we only allocate kva in 1875 * BKVASIZE chunks. 1876 */ 1877 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 1878 1879 if (maxsize != bp->b_kvasize) { 1880 vm_offset_t addr = 0; 1881 1882 bfreekva(bp); 1883 1884 if (vm_map_findspace(buffer_map, 1885 vm_map_min(buffer_map), maxsize, &addr)) { 1886 /* 1887 * Uh oh. Buffer map is to fragmented. We 1888 * must defragment the map. 1889 */ 1890 ++bufdefragcnt; 1891 defrag = 1; 1892 bp->b_flags |= B_INVAL; 1893 brelse(bp); 1894 goto restart; 1895 } 1896 if (addr) { 1897 vm_map_insert(buffer_map, NULL, 0, 1898 addr, addr + maxsize, 1899 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT); 1900 1901 bp->b_kvabase = (caddr_t) addr; 1902 bp->b_kvasize = maxsize; 1903 bufspace += bp->b_kvasize; 1904 ++bufreusecnt; 1905 } 1906 } 1907 bp->b_data = bp->b_kvabase; 1908 } 1909 return(bp); 1910 } 1911 1912 /* 1913 * buf_daemon: 1914 * 1915 * buffer flushing daemon. Buffers are normally flushed by the 1916 * update daemon but if it cannot keep up this process starts to 1917 * take the load in an attempt to prevent getnewbuf() from blocking. 1918 */ 1919 1920 static struct proc *bufdaemonproc; 1921 1922 static struct kproc_desc buf_kp = { 1923 "bufdaemon", 1924 buf_daemon, 1925 &bufdaemonproc 1926 }; 1927 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp) 1928 1929 static void 1930 buf_daemon() 1931 { 1932 int s; 1933 1934 mtx_lock(&Giant); 1935 1936 /* 1937 * This process needs to be suspended prior to shutdown sync. 1938 */ 1939 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 1940 SHUTDOWN_PRI_LAST); 1941 1942 /* 1943 * This process is allowed to take the buffer cache to the limit 1944 */ 1945 s = splbio(); 1946 1947 for (;;) { 1948 kthread_suspend_check(bufdaemonproc); 1949 1950 bd_request = 0; 1951 1952 /* 1953 * Do the flush. Limit the amount of in-transit I/O we 1954 * allow to build up, otherwise we would completely saturate 1955 * the I/O system. Wakeup any waiting processes before we 1956 * normally would so they can run in parallel with our drain. 1957 */ 1958 while (numdirtybuffers > lodirtybuffers) { 1959 if (flushbufqueues() == 0) 1960 break; 1961 waitrunningbufspace(); 1962 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 1963 } 1964 1965 /* 1966 * Only clear bd_request if we have reached our low water 1967 * mark. The buf_daemon normally waits 1 second and 1968 * then incrementally flushes any dirty buffers that have 1969 * built up, within reason. 1970 * 1971 * If we were unable to hit our low water mark and couldn't 1972 * find any flushable buffers, we sleep half a second. 1973 * Otherwise we loop immediately. 1974 */ 1975 if (numdirtybuffers <= lodirtybuffers) { 1976 /* 1977 * We reached our low water mark, reset the 1978 * request and sleep until we are needed again. 1979 * The sleep is just so the suspend code works. 1980 */ 1981 bd_request = 0; 1982 tsleep(&bd_request, PVM, "psleep", hz); 1983 } else { 1984 /* 1985 * We couldn't find any flushable dirty buffers but 1986 * still have too many dirty buffers, we 1987 * have to sleep and try again. (rare) 1988 */ 1989 tsleep(&bd_request, PVM, "qsleep", hz / 2); 1990 } 1991 } 1992 } 1993 1994 /* 1995 * flushbufqueues: 1996 * 1997 * Try to flush a buffer in the dirty queue. We must be careful to 1998 * free up B_INVAL buffers instead of write them, which NFS is 1999 * particularly sensitive to. 2000 */ 2001 2002 static int 2003 flushbufqueues(void) 2004 { 2005 struct buf *bp; 2006 int r = 0; 2007 2008 bp = TAILQ_FIRST(&bufqueues[QUEUE_DIRTY]); 2009 2010 while (bp) { 2011 KASSERT((bp->b_flags & B_DELWRI), ("unexpected clean buffer %p", bp)); 2012 if ((bp->b_flags & B_DELWRI) != 0 && 2013 (bp->b_xflags & BX_BKGRDINPROG) == 0) { 2014 if (bp->b_flags & B_INVAL) { 2015 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) 2016 panic("flushbufqueues: locked buf"); 2017 bremfree(bp); 2018 brelse(bp); 2019 ++r; 2020 break; 2021 } 2022 if (LIST_FIRST(&bp->b_dep) != NULL && 2023 (bp->b_flags & B_DEFERRED) == 0 && 2024 buf_countdeps(bp, 0)) { 2025 TAILQ_REMOVE(&bufqueues[QUEUE_DIRTY], 2026 bp, b_freelist); 2027 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], 2028 bp, b_freelist); 2029 bp->b_flags |= B_DEFERRED; 2030 bp = TAILQ_FIRST(&bufqueues[QUEUE_DIRTY]); 2031 continue; 2032 } 2033 vfs_bio_awrite(bp); 2034 ++r; 2035 break; 2036 } 2037 bp = TAILQ_NEXT(bp, b_freelist); 2038 } 2039 return (r); 2040 } 2041 2042 /* 2043 * Check to see if a block is currently memory resident. 2044 */ 2045 struct buf * 2046 incore(struct vnode * vp, daddr_t blkno) 2047 { 2048 struct buf *bp; 2049 2050 int s = splbio(); 2051 bp = gbincore(vp, blkno); 2052 splx(s); 2053 return (bp); 2054 } 2055 2056 /* 2057 * Returns true if no I/O is needed to access the 2058 * associated VM object. This is like incore except 2059 * it also hunts around in the VM system for the data. 2060 */ 2061 2062 int 2063 inmem(struct vnode * vp, daddr_t blkno) 2064 { 2065 vm_object_t obj; 2066 vm_offset_t toff, tinc, size; 2067 vm_page_t m; 2068 vm_ooffset_t off; 2069 2070 GIANT_REQUIRED; 2071 2072 if (incore(vp, blkno)) 2073 return 1; 2074 if (vp->v_mount == NULL) 2075 return 0; 2076 if (VOP_GETVOBJECT(vp, &obj) != 0 || (vp->v_flag & VOBJBUF) == 0) 2077 return 0; 2078 2079 size = PAGE_SIZE; 2080 if (size > vp->v_mount->mnt_stat.f_iosize) 2081 size = vp->v_mount->mnt_stat.f_iosize; 2082 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2083 2084 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2085 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2086 if (!m) 2087 goto notinmem; 2088 tinc = size; 2089 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2090 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2091 if (vm_page_is_valid(m, 2092 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2093 goto notinmem; 2094 } 2095 return 1; 2096 2097 notinmem: 2098 return (0); 2099 } 2100 2101 /* 2102 * vfs_setdirty: 2103 * 2104 * Sets the dirty range for a buffer based on the status of the dirty 2105 * bits in the pages comprising the buffer. 2106 * 2107 * The range is limited to the size of the buffer. 2108 * 2109 * This routine is primarily used by NFS, but is generalized for the 2110 * B_VMIO case. 2111 */ 2112 static void 2113 vfs_setdirty(struct buf *bp) 2114 { 2115 int i; 2116 vm_object_t object; 2117 2118 GIANT_REQUIRED; 2119 /* 2120 * Degenerate case - empty buffer 2121 */ 2122 2123 if (bp->b_bufsize == 0) 2124 return; 2125 2126 /* 2127 * We qualify the scan for modified pages on whether the 2128 * object has been flushed yet. The OBJ_WRITEABLE flag 2129 * is not cleared simply by protecting pages off. 2130 */ 2131 2132 if ((bp->b_flags & B_VMIO) == 0) 2133 return; 2134 2135 object = bp->b_pages[0]->object; 2136 2137 if ((object->flags & OBJ_WRITEABLE) && !(object->flags & OBJ_MIGHTBEDIRTY)) 2138 printf("Warning: object %p writeable but not mightbedirty\n", object); 2139 if (!(object->flags & OBJ_WRITEABLE) && (object->flags & OBJ_MIGHTBEDIRTY)) 2140 printf("Warning: object %p mightbedirty but not writeable\n", object); 2141 2142 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) { 2143 vm_offset_t boffset; 2144 vm_offset_t eoffset; 2145 2146 /* 2147 * test the pages to see if they have been modified directly 2148 * by users through the VM system. 2149 */ 2150 for (i = 0; i < bp->b_npages; i++) { 2151 vm_page_flag_clear(bp->b_pages[i], PG_ZERO); 2152 vm_page_test_dirty(bp->b_pages[i]); 2153 } 2154 2155 /* 2156 * Calculate the encompassing dirty range, boffset and eoffset, 2157 * (eoffset - boffset) bytes. 2158 */ 2159 2160 for (i = 0; i < bp->b_npages; i++) { 2161 if (bp->b_pages[i]->dirty) 2162 break; 2163 } 2164 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2165 2166 for (i = bp->b_npages - 1; i >= 0; --i) { 2167 if (bp->b_pages[i]->dirty) { 2168 break; 2169 } 2170 } 2171 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2172 2173 /* 2174 * Fit it to the buffer. 2175 */ 2176 2177 if (eoffset > bp->b_bcount) 2178 eoffset = bp->b_bcount; 2179 2180 /* 2181 * If we have a good dirty range, merge with the existing 2182 * dirty range. 2183 */ 2184 2185 if (boffset < eoffset) { 2186 if (bp->b_dirtyoff > boffset) 2187 bp->b_dirtyoff = boffset; 2188 if (bp->b_dirtyend < eoffset) 2189 bp->b_dirtyend = eoffset; 2190 } 2191 } 2192 } 2193 2194 /* 2195 * getblk: 2196 * 2197 * Get a block given a specified block and offset into a file/device. 2198 * The buffers B_DONE bit will be cleared on return, making it almost 2199 * ready for an I/O initiation. B_INVAL may or may not be set on 2200 * return. The caller should clear B_INVAL prior to initiating a 2201 * READ. 2202 * 2203 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2204 * an existing buffer. 2205 * 2206 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2207 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2208 * and then cleared based on the backing VM. If the previous buffer is 2209 * non-0-sized but invalid, B_CACHE will be cleared. 2210 * 2211 * If getblk() must create a new buffer, the new buffer is returned with 2212 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2213 * case it is returned with B_INVAL clear and B_CACHE set based on the 2214 * backing VM. 2215 * 2216 * getblk() also forces a BUF_WRITE() for any B_DELWRI buffer whos 2217 * B_CACHE bit is clear. 2218 * 2219 * What this means, basically, is that the caller should use B_CACHE to 2220 * determine whether the buffer is fully valid or not and should clear 2221 * B_INVAL prior to issuing a read. If the caller intends to validate 2222 * the buffer by loading its data area with something, the caller needs 2223 * to clear B_INVAL. If the caller does this without issuing an I/O, 2224 * the caller should set B_CACHE ( as an optimization ), else the caller 2225 * should issue the I/O and biodone() will set B_CACHE if the I/O was 2226 * a write attempt or if it was a successfull read. If the caller 2227 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 2228 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 2229 */ 2230 struct buf * 2231 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo) 2232 { 2233 struct buf *bp; 2234 int s; 2235 struct bufhashhdr *bh; 2236 2237 if (size > MAXBSIZE) 2238 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 2239 2240 s = splbio(); 2241 loop: 2242 /* 2243 * Block if we are low on buffers. Certain processes are allowed 2244 * to completely exhaust the buffer cache. 2245 * 2246 * If this check ever becomes a bottleneck it may be better to 2247 * move it into the else, when gbincore() fails. At the moment 2248 * it isn't a problem. 2249 * 2250 * XXX remove if 0 sections (clean this up after its proven) 2251 */ 2252 if (numfreebuffers == 0) { 2253 if (curthread == PCPU_GET(idlethread)) 2254 return NULL; 2255 needsbuffer |= VFS_BIO_NEED_ANY; 2256 } 2257 2258 if ((bp = gbincore(vp, blkno))) { 2259 /* 2260 * Buffer is in-core. If the buffer is not busy, it must 2261 * be on a queue. 2262 */ 2263 2264 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) { 2265 if (BUF_TIMELOCK(bp, LK_EXCLUSIVE | LK_SLEEPFAIL, 2266 "getblk", slpflag, slptimeo) == ENOLCK) 2267 goto loop; 2268 splx(s); 2269 return (struct buf *) NULL; 2270 } 2271 2272 /* 2273 * The buffer is locked. B_CACHE is cleared if the buffer is 2274 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 2275 * and for a VMIO buffer B_CACHE is adjusted according to the 2276 * backing VM cache. 2277 */ 2278 if (bp->b_flags & B_INVAL) 2279 bp->b_flags &= ~B_CACHE; 2280 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 2281 bp->b_flags |= B_CACHE; 2282 bremfree(bp); 2283 2284 /* 2285 * check for size inconsistancies for non-VMIO case. 2286 */ 2287 2288 if (bp->b_bcount != size) { 2289 if ((bp->b_flags & B_VMIO) == 0 || 2290 (size > bp->b_kvasize)) { 2291 if (bp->b_flags & B_DELWRI) { 2292 bp->b_flags |= B_NOCACHE; 2293 BUF_WRITE(bp); 2294 } else { 2295 if ((bp->b_flags & B_VMIO) && 2296 (LIST_FIRST(&bp->b_dep) == NULL)) { 2297 bp->b_flags |= B_RELBUF; 2298 brelse(bp); 2299 } else { 2300 bp->b_flags |= B_NOCACHE; 2301 BUF_WRITE(bp); 2302 } 2303 } 2304 goto loop; 2305 } 2306 } 2307 2308 /* 2309 * If the size is inconsistant in the VMIO case, we can resize 2310 * the buffer. This might lead to B_CACHE getting set or 2311 * cleared. If the size has not changed, B_CACHE remains 2312 * unchanged from its previous state. 2313 */ 2314 2315 if (bp->b_bcount != size) 2316 allocbuf(bp, size); 2317 2318 KASSERT(bp->b_offset != NOOFFSET, 2319 ("getblk: no buffer offset")); 2320 2321 /* 2322 * A buffer with B_DELWRI set and B_CACHE clear must 2323 * be committed before we can return the buffer in 2324 * order to prevent the caller from issuing a read 2325 * ( due to B_CACHE not being set ) and overwriting 2326 * it. 2327 * 2328 * Most callers, including NFS and FFS, need this to 2329 * operate properly either because they assume they 2330 * can issue a read if B_CACHE is not set, or because 2331 * ( for example ) an uncached B_DELWRI might loop due 2332 * to softupdates re-dirtying the buffer. In the latter 2333 * case, B_CACHE is set after the first write completes, 2334 * preventing further loops. 2335 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 2336 * above while extending the buffer, we cannot allow the 2337 * buffer to remain with B_CACHE set after the write 2338 * completes or it will represent a corrupt state. To 2339 * deal with this we set B_NOCACHE to scrap the buffer 2340 * after the write. 2341 * 2342 * We might be able to do something fancy, like setting 2343 * B_CACHE in bwrite() except if B_DELWRI is already set, 2344 * so the below call doesn't set B_CACHE, but that gets real 2345 * confusing. This is much easier. 2346 */ 2347 2348 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 2349 bp->b_flags |= B_NOCACHE; 2350 BUF_WRITE(bp); 2351 goto loop; 2352 } 2353 2354 splx(s); 2355 bp->b_flags &= ~B_DONE; 2356 } else { 2357 /* 2358 * Buffer is not in-core, create new buffer. The buffer 2359 * returned by getnewbuf() is locked. Note that the returned 2360 * buffer is also considered valid (not marked B_INVAL). 2361 */ 2362 int bsize, maxsize, vmio; 2363 off_t offset; 2364 2365 if (vn_isdisk(vp, NULL)) 2366 bsize = DEV_BSIZE; 2367 else if (vp->v_mountedhere) 2368 bsize = vp->v_mountedhere->mnt_stat.f_iosize; 2369 else if (vp->v_mount) 2370 bsize = vp->v_mount->mnt_stat.f_iosize; 2371 else 2372 bsize = size; 2373 2374 offset = (off_t)blkno * bsize; 2375 vmio = (VOP_GETVOBJECT(vp, NULL) == 0) && (vp->v_flag & VOBJBUF); 2376 maxsize = vmio ? size + (offset & PAGE_MASK) : size; 2377 maxsize = imax(maxsize, bsize); 2378 2379 if ((bp = getnewbuf(slpflag, slptimeo, size, maxsize)) == NULL) { 2380 if (slpflag || slptimeo) { 2381 splx(s); 2382 return NULL; 2383 } 2384 goto loop; 2385 } 2386 2387 /* 2388 * This code is used to make sure that a buffer is not 2389 * created while the getnewbuf routine is blocked. 2390 * This can be a problem whether the vnode is locked or not. 2391 * If the buffer is created out from under us, we have to 2392 * throw away the one we just created. There is now window 2393 * race because we are safely running at splbio() from the 2394 * point of the duplicate buffer creation through to here, 2395 * and we've locked the buffer. 2396 */ 2397 if (gbincore(vp, blkno)) { 2398 bp->b_flags |= B_INVAL; 2399 brelse(bp); 2400 goto loop; 2401 } 2402 2403 /* 2404 * Insert the buffer into the hash, so that it can 2405 * be found by incore. 2406 */ 2407 bp->b_blkno = bp->b_lblkno = blkno; 2408 bp->b_offset = offset; 2409 2410 bgetvp(vp, bp); 2411 LIST_REMOVE(bp, b_hash); 2412 bh = bufhash(vp, blkno); 2413 LIST_INSERT_HEAD(bh, bp, b_hash); 2414 2415 /* 2416 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 2417 * buffer size starts out as 0, B_CACHE will be set by 2418 * allocbuf() for the VMIO case prior to it testing the 2419 * backing store for validity. 2420 */ 2421 2422 if (vmio) { 2423 bp->b_flags |= B_VMIO; 2424 #if defined(VFS_BIO_DEBUG) 2425 if (vp->v_type != VREG) 2426 printf("getblk: vmioing file type %d???\n", vp->v_type); 2427 #endif 2428 } else { 2429 bp->b_flags &= ~B_VMIO; 2430 } 2431 2432 allocbuf(bp, size); 2433 2434 splx(s); 2435 bp->b_flags &= ~B_DONE; 2436 } 2437 return (bp); 2438 } 2439 2440 /* 2441 * Get an empty, disassociated buffer of given size. The buffer is initially 2442 * set to B_INVAL. 2443 */ 2444 struct buf * 2445 geteblk(int size) 2446 { 2447 struct buf *bp; 2448 int s; 2449 int maxsize; 2450 2451 maxsize = (size + BKVAMASK) & ~BKVAMASK; 2452 2453 s = splbio(); 2454 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0); 2455 splx(s); 2456 allocbuf(bp, size); 2457 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 2458 return (bp); 2459 } 2460 2461 2462 /* 2463 * This code constitutes the buffer memory from either anonymous system 2464 * memory (in the case of non-VMIO operations) or from an associated 2465 * VM object (in the case of VMIO operations). This code is able to 2466 * resize a buffer up or down. 2467 * 2468 * Note that this code is tricky, and has many complications to resolve 2469 * deadlock or inconsistant data situations. Tread lightly!!! 2470 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 2471 * the caller. Calling this code willy nilly can result in the loss of data. 2472 * 2473 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 2474 * B_CACHE for the non-VMIO case. 2475 */ 2476 2477 int 2478 allocbuf(struct buf *bp, int size) 2479 { 2480 int newbsize, mbsize; 2481 int i; 2482 2483 GIANT_REQUIRED; 2484 2485 if (BUF_REFCNT(bp) == 0) 2486 panic("allocbuf: buffer not busy"); 2487 2488 if (bp->b_kvasize < size) 2489 panic("allocbuf: buffer too small"); 2490 2491 if ((bp->b_flags & B_VMIO) == 0) { 2492 caddr_t origbuf; 2493 int origbufsize; 2494 /* 2495 * Just get anonymous memory from the kernel. Don't 2496 * mess with B_CACHE. 2497 */ 2498 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2499 #if !defined(NO_B_MALLOC) 2500 if (bp->b_flags & B_MALLOC) 2501 newbsize = mbsize; 2502 else 2503 #endif 2504 newbsize = round_page(size); 2505 2506 if (newbsize < bp->b_bufsize) { 2507 #if !defined(NO_B_MALLOC) 2508 /* 2509 * malloced buffers are not shrunk 2510 */ 2511 if (bp->b_flags & B_MALLOC) { 2512 if (newbsize) { 2513 bp->b_bcount = size; 2514 } else { 2515 free(bp->b_data, M_BIOBUF); 2516 if (bp->b_bufsize) { 2517 bufmallocspace -= bp->b_bufsize; 2518 bufspacewakeup(); 2519 bp->b_bufsize = 0; 2520 } 2521 bp->b_data = bp->b_kvabase; 2522 bp->b_bcount = 0; 2523 bp->b_flags &= ~B_MALLOC; 2524 } 2525 return 1; 2526 } 2527 #endif 2528 vm_hold_free_pages( 2529 bp, 2530 (vm_offset_t) bp->b_data + newbsize, 2531 (vm_offset_t) bp->b_data + bp->b_bufsize); 2532 } else if (newbsize > bp->b_bufsize) { 2533 #if !defined(NO_B_MALLOC) 2534 /* 2535 * We only use malloced memory on the first allocation. 2536 * and revert to page-allocated memory when the buffer 2537 * grows. 2538 */ 2539 if ( (bufmallocspace < maxbufmallocspace) && 2540 (bp->b_bufsize == 0) && 2541 (mbsize <= PAGE_SIZE/2)) { 2542 2543 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 2544 bp->b_bufsize = mbsize; 2545 bp->b_bcount = size; 2546 bp->b_flags |= B_MALLOC; 2547 bufmallocspace += mbsize; 2548 return 1; 2549 } 2550 #endif 2551 origbuf = NULL; 2552 origbufsize = 0; 2553 #if !defined(NO_B_MALLOC) 2554 /* 2555 * If the buffer is growing on its other-than-first allocation, 2556 * then we revert to the page-allocation scheme. 2557 */ 2558 if (bp->b_flags & B_MALLOC) { 2559 origbuf = bp->b_data; 2560 origbufsize = bp->b_bufsize; 2561 bp->b_data = bp->b_kvabase; 2562 if (bp->b_bufsize) { 2563 bufmallocspace -= bp->b_bufsize; 2564 bufspacewakeup(); 2565 bp->b_bufsize = 0; 2566 } 2567 bp->b_flags &= ~B_MALLOC; 2568 newbsize = round_page(newbsize); 2569 } 2570 #endif 2571 vm_hold_load_pages( 2572 bp, 2573 (vm_offset_t) bp->b_data + bp->b_bufsize, 2574 (vm_offset_t) bp->b_data + newbsize); 2575 #if !defined(NO_B_MALLOC) 2576 if (origbuf) { 2577 bcopy(origbuf, bp->b_data, origbufsize); 2578 free(origbuf, M_BIOBUF); 2579 } 2580 #endif 2581 } 2582 } else { 2583 vm_page_t m; 2584 int desiredpages; 2585 2586 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2587 desiredpages = (size == 0) ? 0 : 2588 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 2589 2590 #if !defined(NO_B_MALLOC) 2591 if (bp->b_flags & B_MALLOC) 2592 panic("allocbuf: VMIO buffer can't be malloced"); 2593 #endif 2594 /* 2595 * Set B_CACHE initially if buffer is 0 length or will become 2596 * 0-length. 2597 */ 2598 if (size == 0 || bp->b_bufsize == 0) 2599 bp->b_flags |= B_CACHE; 2600 2601 if (newbsize < bp->b_bufsize) { 2602 /* 2603 * DEV_BSIZE aligned new buffer size is less then the 2604 * DEV_BSIZE aligned existing buffer size. Figure out 2605 * if we have to remove any pages. 2606 */ 2607 if (desiredpages < bp->b_npages) { 2608 for (i = desiredpages; i < bp->b_npages; i++) { 2609 /* 2610 * the page is not freed here -- it 2611 * is the responsibility of 2612 * vnode_pager_setsize 2613 */ 2614 m = bp->b_pages[i]; 2615 KASSERT(m != bogus_page, 2616 ("allocbuf: bogus page found")); 2617 while (vm_page_sleep_busy(m, TRUE, "biodep")) 2618 ; 2619 2620 bp->b_pages[i] = NULL; 2621 vm_page_unwire(m, 0); 2622 } 2623 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) + 2624 (desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages)); 2625 bp->b_npages = desiredpages; 2626 } 2627 } else if (size > bp->b_bcount) { 2628 /* 2629 * We are growing the buffer, possibly in a 2630 * byte-granular fashion. 2631 */ 2632 struct vnode *vp; 2633 vm_object_t obj; 2634 vm_offset_t toff; 2635 vm_offset_t tinc; 2636 2637 /* 2638 * Step 1, bring in the VM pages from the object, 2639 * allocating them if necessary. We must clear 2640 * B_CACHE if these pages are not valid for the 2641 * range covered by the buffer. 2642 */ 2643 2644 vp = bp->b_vp; 2645 VOP_GETVOBJECT(vp, &obj); 2646 2647 while (bp->b_npages < desiredpages) { 2648 vm_page_t m; 2649 vm_pindex_t pi; 2650 2651 pi = OFF_TO_IDX(bp->b_offset) + bp->b_npages; 2652 if ((m = vm_page_lookup(obj, pi)) == NULL) { 2653 /* 2654 * note: must allocate system pages 2655 * since blocking here could intefere 2656 * with paging I/O, no matter which 2657 * process we are. 2658 */ 2659 m = vm_page_alloc(obj, pi, VM_ALLOC_SYSTEM); 2660 if (m == NULL) { 2661 VM_WAIT; 2662 vm_pageout_deficit += desiredpages - bp->b_npages; 2663 } else { 2664 vm_page_wire(m); 2665 vm_page_wakeup(m); 2666 bp->b_flags &= ~B_CACHE; 2667 bp->b_pages[bp->b_npages] = m; 2668 ++bp->b_npages; 2669 } 2670 continue; 2671 } 2672 2673 /* 2674 * We found a page. If we have to sleep on it, 2675 * retry because it might have gotten freed out 2676 * from under us. 2677 * 2678 * We can only test PG_BUSY here. Blocking on 2679 * m->busy might lead to a deadlock: 2680 * 2681 * vm_fault->getpages->cluster_read->allocbuf 2682 * 2683 */ 2684 2685 if (vm_page_sleep_busy(m, FALSE, "pgtblk")) 2686 continue; 2687 2688 /* 2689 * We have a good page. Should we wakeup the 2690 * page daemon? 2691 */ 2692 if ((curproc != pageproc) && 2693 ((m->queue - m->pc) == PQ_CACHE) && 2694 ((cnt.v_free_count + cnt.v_cache_count) < 2695 (cnt.v_free_min + cnt.v_cache_min))) { 2696 pagedaemon_wakeup(); 2697 } 2698 vm_page_flag_clear(m, PG_ZERO); 2699 vm_page_wire(m); 2700 bp->b_pages[bp->b_npages] = m; 2701 ++bp->b_npages; 2702 } 2703 2704 /* 2705 * Step 2. We've loaded the pages into the buffer, 2706 * we have to figure out if we can still have B_CACHE 2707 * set. Note that B_CACHE is set according to the 2708 * byte-granular range ( bcount and size ), new the 2709 * aligned range ( newbsize ). 2710 * 2711 * The VM test is against m->valid, which is DEV_BSIZE 2712 * aligned. Needless to say, the validity of the data 2713 * needs to also be DEV_BSIZE aligned. Note that this 2714 * fails with NFS if the server or some other client 2715 * extends the file's EOF. If our buffer is resized, 2716 * B_CACHE may remain set! XXX 2717 */ 2718 2719 toff = bp->b_bcount; 2720 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 2721 2722 while ((bp->b_flags & B_CACHE) && toff < size) { 2723 vm_pindex_t pi; 2724 2725 if (tinc > (size - toff)) 2726 tinc = size - toff; 2727 2728 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 2729 PAGE_SHIFT; 2730 2731 vfs_buf_test_cache( 2732 bp, 2733 bp->b_offset, 2734 toff, 2735 tinc, 2736 bp->b_pages[pi] 2737 ); 2738 toff += tinc; 2739 tinc = PAGE_SIZE; 2740 } 2741 2742 /* 2743 * Step 3, fixup the KVM pmap. Remember that 2744 * bp->b_data is relative to bp->b_offset, but 2745 * bp->b_offset may be offset into the first page. 2746 */ 2747 2748 bp->b_data = (caddr_t) 2749 trunc_page((vm_offset_t)bp->b_data); 2750 pmap_qenter( 2751 (vm_offset_t)bp->b_data, 2752 bp->b_pages, 2753 bp->b_npages 2754 ); 2755 2756 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 2757 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 2758 } 2759 } 2760 if (newbsize < bp->b_bufsize) 2761 bufspacewakeup(); 2762 bp->b_bufsize = newbsize; /* actual buffer allocation */ 2763 bp->b_bcount = size; /* requested buffer size */ 2764 return 1; 2765 } 2766 2767 /* 2768 * bufwait: 2769 * 2770 * Wait for buffer I/O completion, returning error status. The buffer 2771 * is left locked and B_DONE on return. B_EINTR is converted into a EINTR 2772 * error and cleared. 2773 */ 2774 int 2775 bufwait(register struct buf * bp) 2776 { 2777 int s; 2778 2779 s = splbio(); 2780 while ((bp->b_flags & B_DONE) == 0) { 2781 if (bp->b_iocmd == BIO_READ) 2782 tsleep(bp, PRIBIO, "biord", 0); 2783 else 2784 tsleep(bp, PRIBIO, "biowr", 0); 2785 } 2786 splx(s); 2787 if (bp->b_flags & B_EINTR) { 2788 bp->b_flags &= ~B_EINTR; 2789 return (EINTR); 2790 } 2791 if (bp->b_ioflags & BIO_ERROR) { 2792 return (bp->b_error ? bp->b_error : EIO); 2793 } else { 2794 return (0); 2795 } 2796 } 2797 2798 /* 2799 * Call back function from struct bio back up to struct buf. 2800 * The corresponding initialization lives in sys/conf.h:DEV_STRATEGY(). 2801 */ 2802 void 2803 bufdonebio(struct bio *bp) 2804 { 2805 bufdone(bp->bio_caller2); 2806 } 2807 2808 /* 2809 * bufdone: 2810 * 2811 * Finish I/O on a buffer, optionally calling a completion function. 2812 * This is usually called from an interrupt so process blocking is 2813 * not allowed. 2814 * 2815 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 2816 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 2817 * assuming B_INVAL is clear. 2818 * 2819 * For the VMIO case, we set B_CACHE if the op was a read and no 2820 * read error occured, or if the op was a write. B_CACHE is never 2821 * set if the buffer is invalid or otherwise uncacheable. 2822 * 2823 * biodone does not mess with B_INVAL, allowing the I/O routine or the 2824 * initiator to leave B_INVAL set to brelse the buffer out of existance 2825 * in the biodone routine. 2826 */ 2827 void 2828 bufdone(struct buf *bp) 2829 { 2830 int s, error; 2831 void (*biodone)(struct buf *); 2832 2833 GIANT_REQUIRED; 2834 2835 s = splbio(); 2836 2837 KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp, BUF_REFCNT(bp))); 2838 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 2839 2840 bp->b_flags |= B_DONE; 2841 runningbufwakeup(bp); 2842 2843 if (bp->b_iocmd == BIO_DELETE) { 2844 brelse(bp); 2845 splx(s); 2846 return; 2847 } 2848 2849 if (bp->b_iocmd == BIO_WRITE) { 2850 vwakeup(bp); 2851 } 2852 2853 /* call optional completion function if requested */ 2854 if (bp->b_iodone != NULL) { 2855 biodone = bp->b_iodone; 2856 bp->b_iodone = NULL; 2857 (*biodone) (bp); 2858 splx(s); 2859 return; 2860 } 2861 if (LIST_FIRST(&bp->b_dep) != NULL) 2862 buf_complete(bp); 2863 2864 if (bp->b_flags & B_VMIO) { 2865 int i; 2866 vm_ooffset_t foff; 2867 vm_page_t m; 2868 vm_object_t obj; 2869 int iosize; 2870 struct vnode *vp = bp->b_vp; 2871 2872 error = VOP_GETVOBJECT(vp, &obj); 2873 2874 #if defined(VFS_BIO_DEBUG) 2875 if (vp->v_usecount == 0) { 2876 panic("biodone: zero vnode ref count"); 2877 } 2878 2879 if (error) { 2880 panic("biodone: missing VM object"); 2881 } 2882 2883 if ((vp->v_flag & VOBJBUF) == 0) { 2884 panic("biodone: vnode is not setup for merged cache"); 2885 } 2886 #endif 2887 2888 foff = bp->b_offset; 2889 KASSERT(bp->b_offset != NOOFFSET, 2890 ("biodone: no buffer offset")); 2891 2892 if (error) { 2893 panic("biodone: no object"); 2894 } 2895 #if defined(VFS_BIO_DEBUG) 2896 if (obj->paging_in_progress < bp->b_npages) { 2897 printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n", 2898 obj->paging_in_progress, bp->b_npages); 2899 } 2900 #endif 2901 2902 /* 2903 * Set B_CACHE if the op was a normal read and no error 2904 * occured. B_CACHE is set for writes in the b*write() 2905 * routines. 2906 */ 2907 iosize = bp->b_bcount - bp->b_resid; 2908 if (bp->b_iocmd == BIO_READ && 2909 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 2910 !(bp->b_ioflags & BIO_ERROR)) { 2911 bp->b_flags |= B_CACHE; 2912 } 2913 2914 for (i = 0; i < bp->b_npages; i++) { 2915 int bogusflag = 0; 2916 int resid; 2917 2918 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 2919 if (resid > iosize) 2920 resid = iosize; 2921 2922 /* 2923 * cleanup bogus pages, restoring the originals 2924 */ 2925 m = bp->b_pages[i]; 2926 if (m == bogus_page) { 2927 bogusflag = 1; 2928 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 2929 if (m == NULL) 2930 panic("biodone: page disappeared!"); 2931 bp->b_pages[i] = m; 2932 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 2933 } 2934 #if defined(VFS_BIO_DEBUG) 2935 if (OFF_TO_IDX(foff) != m->pindex) { 2936 printf( 2937 "biodone: foff(%lu)/m->pindex(%d) mismatch\n", 2938 (unsigned long)foff, m->pindex); 2939 } 2940 #endif 2941 2942 /* 2943 * In the write case, the valid and clean bits are 2944 * already changed correctly ( see bdwrite() ), so we 2945 * only need to do this here in the read case. 2946 */ 2947 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 2948 vfs_page_set_valid(bp, foff, i, m); 2949 } 2950 vm_page_flag_clear(m, PG_ZERO); 2951 2952 /* 2953 * when debugging new filesystems or buffer I/O methods, this 2954 * is the most common error that pops up. if you see this, you 2955 * have not set the page busy flag correctly!!! 2956 */ 2957 if (m->busy == 0) { 2958 printf("biodone: page busy < 0, " 2959 "pindex: %d, foff: 0x(%x,%x), " 2960 "resid: %d, index: %d\n", 2961 (int) m->pindex, (int)(foff >> 32), 2962 (int) foff & 0xffffffff, resid, i); 2963 if (!vn_isdisk(vp, NULL)) 2964 printf(" iosize: %ld, lblkno: %d, flags: 0x%lx, npages: %d\n", 2965 bp->b_vp->v_mount->mnt_stat.f_iosize, 2966 (int) bp->b_lblkno, 2967 bp->b_flags, bp->b_npages); 2968 else 2969 printf(" VDEV, lblkno: %d, flags: 0x%lx, npages: %d\n", 2970 (int) bp->b_lblkno, 2971 bp->b_flags, bp->b_npages); 2972 printf(" valid: 0x%x, dirty: 0x%x, wired: %d\n", 2973 m->valid, m->dirty, m->wire_count); 2974 panic("biodone: page busy < 0\n"); 2975 } 2976 vm_page_io_finish(m); 2977 vm_object_pip_subtract(obj, 1); 2978 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2979 iosize -= resid; 2980 } 2981 if (obj) 2982 vm_object_pip_wakeupn(obj, 0); 2983 } 2984 2985 /* 2986 * For asynchronous completions, release the buffer now. The brelse 2987 * will do a wakeup there if necessary - so no need to do a wakeup 2988 * here in the async case. The sync case always needs to do a wakeup. 2989 */ 2990 2991 if (bp->b_flags & B_ASYNC) { 2992 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 2993 brelse(bp); 2994 else 2995 bqrelse(bp); 2996 } else { 2997 wakeup(bp); 2998 } 2999 splx(s); 3000 } 3001 3002 /* 3003 * This routine is called in lieu of iodone in the case of 3004 * incomplete I/O. This keeps the busy status for pages 3005 * consistant. 3006 */ 3007 void 3008 vfs_unbusy_pages(struct buf * bp) 3009 { 3010 int i; 3011 3012 GIANT_REQUIRED; 3013 3014 runningbufwakeup(bp); 3015 if (bp->b_flags & B_VMIO) { 3016 struct vnode *vp = bp->b_vp; 3017 vm_object_t obj; 3018 3019 VOP_GETVOBJECT(vp, &obj); 3020 3021 for (i = 0; i < bp->b_npages; i++) { 3022 vm_page_t m = bp->b_pages[i]; 3023 3024 if (m == bogus_page) { 3025 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 3026 if (!m) { 3027 panic("vfs_unbusy_pages: page missing\n"); 3028 } 3029 bp->b_pages[i] = m; 3030 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 3031 } 3032 vm_object_pip_subtract(obj, 1); 3033 vm_page_flag_clear(m, PG_ZERO); 3034 vm_page_io_finish(m); 3035 } 3036 vm_object_pip_wakeupn(obj, 0); 3037 } 3038 } 3039 3040 /* 3041 * vfs_page_set_valid: 3042 * 3043 * Set the valid bits in a page based on the supplied offset. The 3044 * range is restricted to the buffer's size. 3045 * 3046 * This routine is typically called after a read completes. 3047 */ 3048 static void 3049 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m) 3050 { 3051 vm_ooffset_t soff, eoff; 3052 3053 GIANT_REQUIRED; 3054 /* 3055 * Start and end offsets in buffer. eoff - soff may not cross a 3056 * page boundry or cross the end of the buffer. The end of the 3057 * buffer, in this case, is our file EOF, not the allocation size 3058 * of the buffer. 3059 */ 3060 soff = off; 3061 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3062 if (eoff > bp->b_offset + bp->b_bcount) 3063 eoff = bp->b_offset + bp->b_bcount; 3064 3065 /* 3066 * Set valid range. This is typically the entire buffer and thus the 3067 * entire page. 3068 */ 3069 if (eoff > soff) { 3070 vm_page_set_validclean( 3071 m, 3072 (vm_offset_t) (soff & PAGE_MASK), 3073 (vm_offset_t) (eoff - soff) 3074 ); 3075 } 3076 } 3077 3078 /* 3079 * This routine is called before a device strategy routine. 3080 * It is used to tell the VM system that paging I/O is in 3081 * progress, and treat the pages associated with the buffer 3082 * almost as being PG_BUSY. Also the object paging_in_progress 3083 * flag is handled to make sure that the object doesn't become 3084 * inconsistant. 3085 * 3086 * Since I/O has not been initiated yet, certain buffer flags 3087 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 3088 * and should be ignored. 3089 */ 3090 void 3091 vfs_busy_pages(struct buf * bp, int clear_modify) 3092 { 3093 int i, bogus; 3094 3095 GIANT_REQUIRED; 3096 3097 if (bp->b_flags & B_VMIO) { 3098 struct vnode *vp = bp->b_vp; 3099 vm_object_t obj; 3100 vm_ooffset_t foff; 3101 3102 VOP_GETVOBJECT(vp, &obj); 3103 foff = bp->b_offset; 3104 KASSERT(bp->b_offset != NOOFFSET, 3105 ("vfs_busy_pages: no buffer offset")); 3106 vfs_setdirty(bp); 3107 3108 retry: 3109 for (i = 0; i < bp->b_npages; i++) { 3110 vm_page_t m = bp->b_pages[i]; 3111 if (vm_page_sleep_busy(m, FALSE, "vbpage")) 3112 goto retry; 3113 } 3114 3115 bogus = 0; 3116 for (i = 0; i < bp->b_npages; i++) { 3117 vm_page_t m = bp->b_pages[i]; 3118 3119 vm_page_flag_clear(m, PG_ZERO); 3120 if ((bp->b_flags & B_CLUSTER) == 0) { 3121 vm_object_pip_add(obj, 1); 3122 vm_page_io_start(m); 3123 } 3124 3125 /* 3126 * When readying a buffer for a read ( i.e 3127 * clear_modify == 0 ), it is important to do 3128 * bogus_page replacement for valid pages in 3129 * partially instantiated buffers. Partially 3130 * instantiated buffers can, in turn, occur when 3131 * reconstituting a buffer from its VM backing store 3132 * base. We only have to do this if B_CACHE is 3133 * clear ( which causes the I/O to occur in the 3134 * first place ). The replacement prevents the read 3135 * I/O from overwriting potentially dirty VM-backed 3136 * pages. XXX bogus page replacement is, uh, bogus. 3137 * It may not work properly with small-block devices. 3138 * We need to find a better way. 3139 */ 3140 3141 vm_page_protect(m, VM_PROT_NONE); 3142 if (clear_modify) 3143 vfs_page_set_valid(bp, foff, i, m); 3144 else if (m->valid == VM_PAGE_BITS_ALL && 3145 (bp->b_flags & B_CACHE) == 0) { 3146 bp->b_pages[i] = bogus_page; 3147 bogus++; 3148 } 3149 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3150 } 3151 if (bogus) 3152 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 3153 } 3154 } 3155 3156 /* 3157 * Tell the VM system that the pages associated with this buffer 3158 * are clean. This is used for delayed writes where the data is 3159 * going to go to disk eventually without additional VM intevention. 3160 * 3161 * Note that while we only really need to clean through to b_bcount, we 3162 * just go ahead and clean through to b_bufsize. 3163 */ 3164 static void 3165 vfs_clean_pages(struct buf * bp) 3166 { 3167 int i; 3168 3169 GIANT_REQUIRED; 3170 3171 if (bp->b_flags & B_VMIO) { 3172 vm_ooffset_t foff; 3173 3174 foff = bp->b_offset; 3175 KASSERT(bp->b_offset != NOOFFSET, 3176 ("vfs_clean_pages: no buffer offset")); 3177 for (i = 0; i < bp->b_npages; i++) { 3178 vm_page_t m = bp->b_pages[i]; 3179 vm_ooffset_t noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3180 vm_ooffset_t eoff = noff; 3181 3182 if (eoff > bp->b_offset + bp->b_bufsize) 3183 eoff = bp->b_offset + bp->b_bufsize; 3184 vfs_page_set_valid(bp, foff, i, m); 3185 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3186 foff = noff; 3187 } 3188 } 3189 } 3190 3191 /* 3192 * vfs_bio_set_validclean: 3193 * 3194 * Set the range within the buffer to valid and clean. The range is 3195 * relative to the beginning of the buffer, b_offset. Note that b_offset 3196 * itself may be offset from the beginning of the first page. 3197 * 3198 */ 3199 3200 void 3201 vfs_bio_set_validclean(struct buf *bp, int base, int size) 3202 { 3203 if (bp->b_flags & B_VMIO) { 3204 int i; 3205 int n; 3206 3207 /* 3208 * Fixup base to be relative to beginning of first page. 3209 * Set initial n to be the maximum number of bytes in the 3210 * first page that can be validated. 3211 */ 3212 3213 base += (bp->b_offset & PAGE_MASK); 3214 n = PAGE_SIZE - (base & PAGE_MASK); 3215 3216 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 3217 vm_page_t m = bp->b_pages[i]; 3218 3219 if (n > size) 3220 n = size; 3221 3222 vm_page_set_validclean(m, base & PAGE_MASK, n); 3223 base += n; 3224 size -= n; 3225 n = PAGE_SIZE; 3226 } 3227 } 3228 } 3229 3230 /* 3231 * vfs_bio_clrbuf: 3232 * 3233 * clear a buffer. This routine essentially fakes an I/O, so we need 3234 * to clear BIO_ERROR and B_INVAL. 3235 * 3236 * Note that while we only theoretically need to clear through b_bcount, 3237 * we go ahead and clear through b_bufsize. 3238 */ 3239 3240 void 3241 vfs_bio_clrbuf(struct buf *bp) { 3242 int i, mask = 0; 3243 caddr_t sa, ea; 3244 3245 GIANT_REQUIRED; 3246 3247 if ((bp->b_flags & (B_VMIO | B_MALLOC)) == B_VMIO) { 3248 bp->b_flags &= ~B_INVAL; 3249 bp->b_ioflags &= ~BIO_ERROR; 3250 if( (bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 3251 (bp->b_offset & PAGE_MASK) == 0) { 3252 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 3253 if (((bp->b_pages[0]->flags & PG_ZERO) == 0) && 3254 ((bp->b_pages[0]->valid & mask) != mask)) { 3255 bzero(bp->b_data, bp->b_bufsize); 3256 } 3257 bp->b_pages[0]->valid |= mask; 3258 bp->b_resid = 0; 3259 return; 3260 } 3261 ea = sa = bp->b_data; 3262 for(i=0;i<bp->b_npages;i++,sa=ea) { 3263 int j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; 3264 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); 3265 ea = (caddr_t)(vm_offset_t)ulmin( 3266 (u_long)(vm_offset_t)ea, 3267 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); 3268 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 3269 if ((bp->b_pages[i]->valid & mask) == mask) 3270 continue; 3271 if ((bp->b_pages[i]->valid & mask) == 0) { 3272 if ((bp->b_pages[i]->flags & PG_ZERO) == 0) { 3273 bzero(sa, ea - sa); 3274 } 3275 } else { 3276 for (; sa < ea; sa += DEV_BSIZE, j++) { 3277 if (((bp->b_pages[i]->flags & PG_ZERO) == 0) && 3278 (bp->b_pages[i]->valid & (1<<j)) == 0) 3279 bzero(sa, DEV_BSIZE); 3280 } 3281 } 3282 bp->b_pages[i]->valid |= mask; 3283 vm_page_flag_clear(bp->b_pages[i], PG_ZERO); 3284 } 3285 bp->b_resid = 0; 3286 } else { 3287 clrbuf(bp); 3288 } 3289 } 3290 3291 /* 3292 * vm_hold_load_pages and vm_hold_free_pages get pages into 3293 * a buffers address space. The pages are anonymous and are 3294 * not associated with a file object. 3295 */ 3296 static void 3297 vm_hold_load_pages(struct buf * bp, vm_offset_t from, vm_offset_t to) 3298 { 3299 vm_offset_t pg; 3300 vm_page_t p; 3301 int index; 3302 3303 GIANT_REQUIRED; 3304 3305 to = round_page(to); 3306 from = round_page(from); 3307 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3308 3309 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3310 tryagain: 3311 /* 3312 * note: must allocate system pages since blocking here 3313 * could intefere with paging I/O, no matter which 3314 * process we are. 3315 */ 3316 p = vm_page_alloc(kernel_object, 3317 ((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 3318 VM_ALLOC_SYSTEM); 3319 if (!p) { 3320 vm_pageout_deficit += (to - from) >> PAGE_SHIFT; 3321 VM_WAIT; 3322 goto tryagain; 3323 } 3324 vm_page_wire(p); 3325 p->valid = VM_PAGE_BITS_ALL; 3326 vm_page_flag_clear(p, PG_ZERO); 3327 pmap_qenter(pg, &p, 1); 3328 bp->b_pages[index] = p; 3329 vm_page_wakeup(p); 3330 } 3331 bp->b_npages = index; 3332 } 3333 3334 /* Return pages associated with this buf to the vm system */ 3335 void 3336 vm_hold_free_pages(struct buf * bp, vm_offset_t from, vm_offset_t to) 3337 { 3338 vm_offset_t pg; 3339 vm_page_t p; 3340 int index, newnpages; 3341 3342 GIANT_REQUIRED; 3343 3344 from = round_page(from); 3345 to = round_page(to); 3346 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3347 3348 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3349 p = bp->b_pages[index]; 3350 if (p && (index < bp->b_npages)) { 3351 if (p->busy) { 3352 printf( 3353 "vm_hold_free_pages: blkno: %lld, lblkno: %lld\n", 3354 (long long)bp->b_blkno, 3355 (long long)bp->b_lblkno); 3356 } 3357 bp->b_pages[index] = NULL; 3358 pmap_qremove(pg, 1); 3359 vm_page_busy(p); 3360 vm_page_unwire(p, 0); 3361 vm_page_free(p); 3362 } 3363 } 3364 bp->b_npages = newnpages; 3365 } 3366 3367 3368 #include "opt_ddb.h" 3369 #ifdef DDB 3370 #include <ddb/ddb.h> 3371 3372 /* DDB command to show buffer data */ 3373 DB_SHOW_COMMAND(buffer, db_show_buffer) 3374 { 3375 /* get args */ 3376 struct buf *bp = (struct buf *)addr; 3377 3378 if (!have_addr) { 3379 db_printf("usage: show buffer <addr>\n"); 3380 return; 3381 } 3382 3383 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS); 3384 db_printf( 3385 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 3386 "b_dev = (%d,%d), b_data = %p, b_blkno = %lld, b_pblkno = %lld\n", 3387 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 3388 major(bp->b_dev), minor(bp->b_dev), bp->b_data, 3389 (long long)bp->b_blkno, (long long)bp->b_pblkno); 3390 if (bp->b_npages) { 3391 int i; 3392 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 3393 for (i = 0; i < bp->b_npages; i++) { 3394 vm_page_t m; 3395 m = bp->b_pages[i]; 3396 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 3397 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 3398 if ((i + 1) < bp->b_npages) 3399 db_printf(","); 3400 } 3401 db_printf("\n"); 3402 } 3403 } 3404 #endif /* DDB */ 3405