vfs_bio.c revision 103314
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: head/sys/kern/vfs_bio.c 103314 2002-09-14 09:02:28Z njl $ 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/stdint.h> 33#include <sys/bio.h> 34#include <sys/buf.h> 35#include <sys/eventhandler.h> 36#include <sys/lock.h> 37#include <sys/malloc.h> 38#include <sys/mount.h> 39#include <sys/mutex.h> 40#include <sys/kernel.h> 41#include <sys/kthread.h> 42#include <sys/ktr.h> 43#include <sys/proc.h> 44#include <sys/reboot.h> 45#include <sys/resourcevar.h> 46#include <sys/sysctl.h> 47#include <sys/vmmeter.h> 48#include <sys/vnode.h> 49#include <vm/vm.h> 50#include <vm/vm_param.h> 51#include <vm/vm_kern.h> 52#include <vm/vm_pageout.h> 53#include <vm/vm_page.h> 54#include <vm/vm_object.h> 55#include <vm/vm_extern.h> 56#include <vm/vm_map.h> 57 58static MALLOC_DEFINE(M_BIOBUF, "BIO buffer", "BIO buffer"); 59 60struct bio_ops bioops; /* I/O operation notification */ 61 62struct buf_ops buf_ops_bio = { 63 "buf_ops_bio", 64 bwrite 65}; 66 67/* 68 * XXX buf is global because kern_shutdown.c and ffs_checkoverlap has 69 * carnal knowledge of buffers. This knowledge should be moved to vfs_bio.c. 70 */ 71struct buf *buf; /* buffer header pool */ 72struct mtx buftimelock; /* Interlock on setting prio and timo */ 73 74static void vm_hold_free_pages(struct buf * bp, vm_offset_t from, 75 vm_offset_t to); 76static void vm_hold_load_pages(struct buf * bp, vm_offset_t from, 77 vm_offset_t to); 78static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, 79 int pageno, vm_page_t m); 80static void vfs_clean_pages(struct buf * bp); 81static void vfs_setdirty(struct buf *bp); 82static void vfs_vmio_release(struct buf *bp); 83static void vfs_backgroundwritedone(struct buf *bp); 84static int flushbufqueues(void); 85static void buf_daemon(void); 86 87int vmiodirenable = TRUE; 88SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, 89 "Use the VM system for directory writes"); 90int runningbufspace; 91SYSCTL_INT(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 92 "Amount of presently outstanding async buffer io"); 93static int bufspace; 94SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, 95 "KVA memory used for bufs"); 96static int maxbufspace; 97SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0, 98 "Maximum allowed value of bufspace (including buf_daemon)"); 99static int bufmallocspace; 100SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 101 "Amount of malloced memory for buffers"); 102static int maxbufmallocspace; 103SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0, 104 "Maximum amount of malloced memory for buffers"); 105static int lobufspace; 106SYSCTL_INT(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0, 107 "Minimum amount of buffers we want to have"); 108static int hibufspace; 109SYSCTL_INT(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0, 110 "Maximum allowed value of bufspace (excluding buf_daemon)"); 111static int bufreusecnt; 112SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0, 113 "Number of times we have reused a buffer"); 114static int buffreekvacnt; 115SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0, 116 "Number of times we have freed the KVA space from some buffer"); 117static int bufdefragcnt; 118SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0, 119 "Number of times we have had to repeat buffer allocation to defragment"); 120static int lorunningspace; 121SYSCTL_INT(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0, 122 "Minimum preferred space used for in-progress I/O"); 123static int hirunningspace; 124SYSCTL_INT(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0, 125 "Maximum amount of space to use for in-progress I/O"); 126static int numdirtybuffers; 127SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0, 128 "Number of buffers that are dirty (has unwritten changes) at the moment"); 129static int lodirtybuffers; 130SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0, 131 "How many buffers we want to have free before bufdaemon can sleep"); 132static int hidirtybuffers; 133SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0, 134 "When the number of dirty buffers is considered severe"); 135static int numfreebuffers; 136SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, 137 "Number of free buffers"); 138static int lofreebuffers; 139SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0, 140 "XXX Unused"); 141static int hifreebuffers; 142SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0, 143 "XXX Complicatedly unused"); 144static int getnewbufcalls; 145SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0, 146 "Number of calls to getnewbuf"); 147static int getnewbufrestarts; 148SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0, 149 "Number of times getnewbuf has had to restart a buffer aquisition"); 150static int dobkgrdwrite = 1; 151SYSCTL_INT(_debug, OID_AUTO, dobkgrdwrite, CTLFLAG_RW, &dobkgrdwrite, 0, 152 "Do background writes (honoring the BX_BKGRDWRITE flag)?"); 153 154/* 155 * Wakeup point for bufdaemon, as well as indicator of whether it is already 156 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it 157 * is idling. 158 */ 159static int bd_request; 160 161/* 162 * bogus page -- for I/O to/from partially complete buffers 163 * this is a temporary solution to the problem, but it is not 164 * really that bad. it would be better to split the buffer 165 * for input in the case of buffers partially already in memory, 166 * but the code is intricate enough already. 167 */ 168vm_page_t bogus_page; 169 170/* 171 * Offset for bogus_page. 172 * XXX bogus_offset should be local to bufinit 173 */ 174static vm_offset_t bogus_offset; 175 176/* 177 * Synchronization (sleep/wakeup) variable for active buffer space requests. 178 * Set when wait starts, cleared prior to wakeup(). 179 * Used in runningbufwakeup() and waitrunningbufspace(). 180 */ 181static int runningbufreq; 182 183/* 184 * Synchronization (sleep/wakeup) variable for buffer requests. 185 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done 186 * by and/or. 187 * Used in numdirtywakeup(), bufspacewakeup(), bufcountwakeup(), bwillwrite(), 188 * getnewbuf(), and getblk(). 189 */ 190static int needsbuffer; 191 192#ifdef USE_BUFHASH 193/* 194 * Mask for index into the buffer hash table, which needs to be power of 2 in 195 * size. Set in kern_vfs_bio_buffer_alloc. 196 */ 197static int bufhashmask; 198 199/* 200 * Hash table for all buffers, with a linked list hanging from each table 201 * entry. Set in kern_vfs_bio_buffer_alloc, initialized in buf_init. 202 */ 203static LIST_HEAD(bufhashhdr, buf) *bufhashtbl; 204 205/* 206 * Somewhere to store buffers when they are not in another list, to always 207 * have them in a list (and thus being able to use the same set of operations 208 * on them.) 209 */ 210static struct bufhashhdr invalhash; 211 212#endif 213 214/* 215 * Definitions for the buffer free lists. 216 */ 217#define BUFFER_QUEUES 6 /* number of free buffer queues */ 218 219#define QUEUE_NONE 0 /* on no queue */ 220#define QUEUE_LOCKED 1 /* locked buffers */ 221#define QUEUE_CLEAN 2 /* non-B_DELWRI buffers */ 222#define QUEUE_DIRTY 3 /* B_DELWRI buffers */ 223#define QUEUE_EMPTYKVA 4 /* empty buffer headers w/KVA assignment */ 224#define QUEUE_EMPTY 5 /* empty buffer headers */ 225 226/* Queues for free buffers with various properties */ 227static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } }; 228/* 229 * Single global constant for BUF_WMESG, to avoid getting multiple references. 230 * buf_wmesg is referred from macros. 231 */ 232const char *buf_wmesg = BUF_WMESG; 233 234#define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 235#define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */ 236#define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ 237#define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 238 239#ifdef USE_BUFHASH 240/* 241 * Buffer hash table code. Note that the logical block scans linearly, which 242 * gives us some L1 cache locality. 243 */ 244 245static __inline 246struct bufhashhdr * 247bufhash(struct vnode *vnp, daddr_t bn) 248{ 249 return(&bufhashtbl[(((uintptr_t)(vnp) >> 7) + (int)bn) & bufhashmask]); 250} 251 252#endif 253 254/* 255 * numdirtywakeup: 256 * 257 * If someone is blocked due to there being too many dirty buffers, 258 * and numdirtybuffers is now reasonable, wake them up. 259 */ 260 261static __inline void 262numdirtywakeup(int level) 263{ 264 if (numdirtybuffers <= level) { 265 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) { 266 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH; 267 wakeup(&needsbuffer); 268 } 269 } 270} 271 272/* 273 * bufspacewakeup: 274 * 275 * Called when buffer space is potentially available for recovery. 276 * getnewbuf() will block on this flag when it is unable to free 277 * sufficient buffer space. Buffer space becomes recoverable when 278 * bp's get placed back in the queues. 279 */ 280 281static __inline void 282bufspacewakeup(void) 283{ 284 /* 285 * If someone is waiting for BUF space, wake them up. Even 286 * though we haven't freed the kva space yet, the waiting 287 * process will be able to now. 288 */ 289 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) { 290 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE; 291 wakeup(&needsbuffer); 292 } 293} 294 295/* 296 * runningbufwakeup() - in-progress I/O accounting. 297 * 298 */ 299static __inline void 300runningbufwakeup(struct buf *bp) 301{ 302 if (bp->b_runningbufspace) { 303 runningbufspace -= bp->b_runningbufspace; 304 bp->b_runningbufspace = 0; 305 if (runningbufreq && runningbufspace <= lorunningspace) { 306 runningbufreq = 0; 307 wakeup(&runningbufreq); 308 } 309 } 310} 311 312/* 313 * bufcountwakeup: 314 * 315 * Called when a buffer has been added to one of the free queues to 316 * account for the buffer and to wakeup anyone waiting for free buffers. 317 * This typically occurs when large amounts of metadata are being handled 318 * by the buffer cache ( else buffer space runs out first, usually ). 319 */ 320 321static __inline void 322bufcountwakeup(void) 323{ 324 ++numfreebuffers; 325 if (needsbuffer) { 326 needsbuffer &= ~VFS_BIO_NEED_ANY; 327 if (numfreebuffers >= hifreebuffers) 328 needsbuffer &= ~VFS_BIO_NEED_FREE; 329 wakeup(&needsbuffer); 330 } 331} 332 333/* 334 * waitrunningbufspace() 335 * 336 * runningbufspace is a measure of the amount of I/O currently 337 * running. This routine is used in async-write situations to 338 * prevent creating huge backups of pending writes to a device. 339 * Only asynchronous writes are governed by this function. 340 * 341 * Reads will adjust runningbufspace, but will not block based on it. 342 * The read load has a side effect of reducing the allowed write load. 343 * 344 * This does NOT turn an async write into a sync write. It waits 345 * for earlier writes to complete and generally returns before the 346 * caller's write has reached the device. 347 */ 348static __inline void 349waitrunningbufspace(void) 350{ 351 /* 352 * XXX race against wakeup interrupt, currently 353 * protected by Giant. FIXME! 354 */ 355 while (runningbufspace > hirunningspace) { 356 ++runningbufreq; 357 tsleep(&runningbufreq, PVM, "wdrain", 0); 358 } 359} 360 361 362/* 363 * vfs_buf_test_cache: 364 * 365 * Called when a buffer is extended. This function clears the B_CACHE 366 * bit if the newly extended portion of the buffer does not contain 367 * valid data. 368 */ 369static __inline__ 370void 371vfs_buf_test_cache(struct buf *bp, 372 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 373 vm_page_t m) 374{ 375 GIANT_REQUIRED; 376 377 if (bp->b_flags & B_CACHE) { 378 int base = (foff + off) & PAGE_MASK; 379 if (vm_page_is_valid(m, base, size) == 0) 380 bp->b_flags &= ~B_CACHE; 381 } 382} 383 384/* Wake up the buffer deamon if necessary */ 385static __inline__ 386void 387bd_wakeup(int dirtybuflevel) 388{ 389 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) { 390 bd_request = 1; 391 wakeup(&bd_request); 392 } 393} 394 395/* 396 * bd_speedup - speedup the buffer cache flushing code 397 */ 398 399static __inline__ 400void 401bd_speedup(void) 402{ 403 bd_wakeup(1); 404} 405 406/* 407 * Calculating buffer cache scaling values and reserve space for buffer 408 * headers. This is called during low level kernel initialization and 409 * may be called more then once. We CANNOT write to the memory area 410 * being reserved at this time. 411 */ 412caddr_t 413kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 414{ 415 /* 416 * physmem_est is in pages. Convert it to kilobytes (assumes 417 * PAGE_SIZE is >= 1K) 418 */ 419 physmem_est = physmem_est * (PAGE_SIZE / 1024); 420 421 /* 422 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 423 * For the first 64MB of ram nominally allocate sufficient buffers to 424 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 425 * buffers to cover 1/20 of our ram over 64MB. When auto-sizing 426 * the buffer cache we limit the eventual kva reservation to 427 * maxbcache bytes. 428 * 429 * factor represents the 1/4 x ram conversion. 430 */ 431 if (nbuf == 0) { 432 int factor = 4 * BKVASIZE / 1024; 433 434 nbuf = 50; 435 if (physmem_est > 4096) 436 nbuf += min((physmem_est - 4096) / factor, 437 65536 / factor); 438 if (physmem_est > 65536) 439 nbuf += (physmem_est - 65536) * 2 / (factor * 5); 440 441 if (maxbcache && nbuf > maxbcache / BKVASIZE) 442 nbuf = maxbcache / BKVASIZE; 443 } 444 445#if 0 446 /* 447 * Do not allow the buffer_map to be more then 1/2 the size of the 448 * kernel_map. 449 */ 450 if (nbuf > (kernel_map->max_offset - kernel_map->min_offset) / 451 (BKVASIZE * 2)) { 452 nbuf = (kernel_map->max_offset - kernel_map->min_offset) / 453 (BKVASIZE * 2); 454 printf("Warning: nbufs capped at %d\n", nbuf); 455 } 456#endif 457 458 /* 459 * swbufs are used as temporary holders for I/O, such as paging I/O. 460 * We have no less then 16 and no more then 256. 461 */ 462 nswbuf = max(min(nbuf/4, 256), 16); 463 464 /* 465 * Reserve space for the buffer cache buffers 466 */ 467 swbuf = (void *)v; 468 v = (caddr_t)(swbuf + nswbuf); 469 buf = (void *)v; 470 v = (caddr_t)(buf + nbuf); 471 472#ifdef USE_BUFHASH 473 /* 474 * Calculate the hash table size and reserve space 475 */ 476 for (bufhashmask = 8; bufhashmask < nbuf / 4; bufhashmask <<= 1) 477 ; 478 bufhashtbl = (void *)v; 479 v = (caddr_t)(bufhashtbl + bufhashmask); 480 --bufhashmask; 481#endif 482 return(v); 483} 484 485/* Initialize the buffer subsystem. Called before use of any buffers. */ 486void 487bufinit(void) 488{ 489 struct buf *bp; 490 int i; 491 492 GIANT_REQUIRED; 493 494#ifdef USE_BUFHASH 495 LIST_INIT(&invalhash); 496#endif 497 mtx_init(&buftimelock, "buftime lock", NULL, MTX_DEF); 498 499#ifdef USE_BUFHASH 500 for (i = 0; i <= bufhashmask; i++) 501 LIST_INIT(&bufhashtbl[i]); 502#endif 503 504 /* next, make a null set of free lists */ 505 for (i = 0; i < BUFFER_QUEUES; i++) 506 TAILQ_INIT(&bufqueues[i]); 507 508 /* finally, initialize each buffer header and stick on empty q */ 509 for (i = 0; i < nbuf; i++) { 510 bp = &buf[i]; 511 bzero(bp, sizeof *bp); 512 bp->b_flags = B_INVAL; /* we're just an empty header */ 513 bp->b_dev = NODEV; 514 bp->b_rcred = NOCRED; 515 bp->b_wcred = NOCRED; 516 bp->b_qindex = QUEUE_EMPTY; 517 bp->b_xflags = 0; 518 LIST_INIT(&bp->b_dep); 519 BUF_LOCKINIT(bp); 520 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 521#ifdef USE_BUFHASH 522 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 523#endif 524 } 525 526 /* 527 * maxbufspace is the absolute maximum amount of buffer space we are 528 * allowed to reserve in KVM and in real terms. The absolute maximum 529 * is nominally used by buf_daemon. hibufspace is the nominal maximum 530 * used by most other processes. The differential is required to 531 * ensure that buf_daemon is able to run when other processes might 532 * be blocked waiting for buffer space. 533 * 534 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 535 * this may result in KVM fragmentation which is not handled optimally 536 * by the system. 537 */ 538 maxbufspace = nbuf * BKVASIZE; 539 hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 540 lobufspace = hibufspace - MAXBSIZE; 541 542 lorunningspace = 512 * 1024; 543 hirunningspace = 1024 * 1024; 544 545/* 546 * Limit the amount of malloc memory since it is wired permanently into 547 * the kernel space. Even though this is accounted for in the buffer 548 * allocation, we don't want the malloced region to grow uncontrolled. 549 * The malloc scheme improves memory utilization significantly on average 550 * (small) directories. 551 */ 552 maxbufmallocspace = hibufspace / 20; 553 554/* 555 * Reduce the chance of a deadlock occuring by limiting the number 556 * of delayed-write dirty buffers we allow to stack up. 557 */ 558 hidirtybuffers = nbuf / 4 + 20; 559 numdirtybuffers = 0; 560/* 561 * To support extreme low-memory systems, make sure hidirtybuffers cannot 562 * eat up all available buffer space. This occurs when our minimum cannot 563 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 564 * BKVASIZE'd (8K) buffers. 565 */ 566 while (hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 567 hidirtybuffers >>= 1; 568 } 569 lodirtybuffers = hidirtybuffers / 2; 570 571/* 572 * Try to keep the number of free buffers in the specified range, 573 * and give special processes (e.g. like buf_daemon) access to an 574 * emergency reserve. 575 */ 576 lofreebuffers = nbuf / 18 + 5; 577 hifreebuffers = 2 * lofreebuffers; 578 numfreebuffers = nbuf; 579 580/* 581 * Maximum number of async ops initiated per buf_daemon loop. This is 582 * somewhat of a hack at the moment, we really need to limit ourselves 583 * based on the number of bytes of I/O in-transit that were initiated 584 * from buf_daemon. 585 */ 586 587 bogus_offset = kmem_alloc_pageable(kernel_map, PAGE_SIZE); 588 bogus_page = vm_page_alloc(kernel_object, 589 ((bogus_offset - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 590 VM_ALLOC_NORMAL); 591 cnt.v_wire_count++; 592} 593 594/* 595 * bfreekva() - free the kva allocation for a buffer. 596 * 597 * Must be called at splbio() or higher as this is the only locking for 598 * buffer_map. 599 * 600 * Since this call frees up buffer space, we call bufspacewakeup(). 601 */ 602static void 603bfreekva(struct buf * bp) 604{ 605 GIANT_REQUIRED; 606 607 if (bp->b_kvasize) { 608 ++buffreekvacnt; 609 bufspace -= bp->b_kvasize; 610 vm_map_delete(buffer_map, 611 (vm_offset_t) bp->b_kvabase, 612 (vm_offset_t) bp->b_kvabase + bp->b_kvasize 613 ); 614 bp->b_kvasize = 0; 615 bufspacewakeup(); 616 } 617} 618 619/* 620 * bremfree: 621 * 622 * Remove the buffer from the appropriate free list. 623 */ 624void 625bremfree(struct buf * bp) 626{ 627 int s = splbio(); 628 int old_qindex = bp->b_qindex; 629 630 GIANT_REQUIRED; 631 632 if (bp->b_qindex != QUEUE_NONE) { 633 KASSERT(BUF_REFCNT(bp) == 1, ("bremfree: bp %p not locked",bp)); 634 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 635 bp->b_qindex = QUEUE_NONE; 636 } else { 637 if (BUF_REFCNT(bp) <= 1) 638 panic("bremfree: removing a buffer not on a queue"); 639 } 640 641 /* 642 * Fixup numfreebuffers count. If the buffer is invalid or not 643 * delayed-write, and it was on the EMPTY, LRU, or AGE queues, 644 * the buffer was free and we must decrement numfreebuffers. 645 */ 646 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { 647 switch(old_qindex) { 648 case QUEUE_DIRTY: 649 case QUEUE_CLEAN: 650 case QUEUE_EMPTY: 651 case QUEUE_EMPTYKVA: 652 --numfreebuffers; 653 break; 654 default: 655 break; 656 } 657 } 658 splx(s); 659} 660 661 662/* 663 * Get a buffer with the specified data. Look in the cache first. We 664 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 665 * is set, the buffer is valid and we do not have to do anything ( see 666 * getblk() ). This is really just a special case of breadn(). 667 */ 668int 669bread(struct vnode * vp, daddr_t blkno, int size, struct ucred * cred, 670 struct buf ** bpp) 671{ 672 673 return (breadn(vp, blkno, size, 0, 0, 0, cred, bpp)); 674} 675 676/* 677 * Operates like bread, but also starts asynchronous I/O on 678 * read-ahead blocks. We must clear BIO_ERROR and B_INVAL prior 679 * to initiating I/O . If B_CACHE is set, the buffer is valid 680 * and we do not have to do anything. 681 */ 682int 683breadn(struct vnode * vp, daddr_t blkno, int size, 684 daddr_t * rablkno, int *rabsize, 685 int cnt, struct ucred * cred, struct buf ** bpp) 686{ 687 struct buf *bp, *rabp; 688 int i; 689 int rv = 0, readwait = 0; 690 691 *bpp = bp = getblk(vp, blkno, size, 0, 0); 692 693 /* if not found in cache, do some I/O */ 694 if ((bp->b_flags & B_CACHE) == 0) { 695 if (curthread != PCPU_GET(idlethread)) 696 curthread->td_proc->p_stats->p_ru.ru_inblock++; 697 bp->b_iocmd = BIO_READ; 698 bp->b_flags &= ~B_INVAL; 699 bp->b_ioflags &= ~BIO_ERROR; 700 if (bp->b_rcred == NOCRED && cred != NOCRED) 701 bp->b_rcred = crhold(cred); 702 vfs_busy_pages(bp, 0); 703 VOP_STRATEGY(vp, bp); 704 ++readwait; 705 } 706 707 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 708 if (inmem(vp, *rablkno)) 709 continue; 710 rabp = getblk(vp, *rablkno, *rabsize, 0, 0); 711 712 if ((rabp->b_flags & B_CACHE) == 0) { 713 if (curthread != PCPU_GET(idlethread)) 714 curthread->td_proc->p_stats->p_ru.ru_inblock++; 715 rabp->b_flags |= B_ASYNC; 716 rabp->b_flags &= ~B_INVAL; 717 rabp->b_ioflags &= ~BIO_ERROR; 718 rabp->b_iocmd = BIO_READ; 719 if (rabp->b_rcred == NOCRED && cred != NOCRED) 720 rabp->b_rcred = crhold(cred); 721 vfs_busy_pages(rabp, 0); 722 BUF_KERNPROC(rabp); 723 VOP_STRATEGY(vp, rabp); 724 } else { 725 brelse(rabp); 726 } 727 } 728 729 if (readwait) { 730 rv = bufwait(bp); 731 } 732 return (rv); 733} 734 735/* 736 * Write, release buffer on completion. (Done by iodone 737 * if async). Do not bother writing anything if the buffer 738 * is invalid. 739 * 740 * Note that we set B_CACHE here, indicating that buffer is 741 * fully valid and thus cacheable. This is true even of NFS 742 * now so we set it generally. This could be set either here 743 * or in biodone() since the I/O is synchronous. We put it 744 * here. 745 */ 746 747int 748bwrite(struct buf * bp) 749{ 750 int oldflags, s; 751 struct buf *newbp; 752 753 if (bp->b_flags & B_INVAL) { 754 brelse(bp); 755 return (0); 756 } 757 758 oldflags = bp->b_flags; 759 760 if (BUF_REFCNT(bp) == 0) 761 panic("bwrite: buffer is not busy???"); 762 s = splbio(); 763 /* 764 * If a background write is already in progress, delay 765 * writing this block if it is asynchronous. Otherwise 766 * wait for the background write to complete. 767 */ 768 if (bp->b_xflags & BX_BKGRDINPROG) { 769 if (bp->b_flags & B_ASYNC) { 770 splx(s); 771 bdwrite(bp); 772 return (0); 773 } 774 bp->b_xflags |= BX_BKGRDWAIT; 775 tsleep(&bp->b_xflags, PRIBIO, "bwrbg", 0); 776 if (bp->b_xflags & BX_BKGRDINPROG) 777 panic("bwrite: still writing"); 778 } 779 780 /* Mark the buffer clean */ 781 bundirty(bp); 782 783 /* 784 * If this buffer is marked for background writing and we 785 * do not have to wait for it, make a copy and write the 786 * copy so as to leave this buffer ready for further use. 787 * 788 * This optimization eats a lot of memory. If we have a page 789 * or buffer shortfall we can't do it. 790 */ 791 if (dobkgrdwrite && (bp->b_xflags & BX_BKGRDWRITE) && 792 (bp->b_flags & B_ASYNC) && 793 !vm_page_count_severe() && 794 !buf_dirty_count_severe()) { 795 if (bp->b_iodone != NULL) { 796 printf("bp->b_iodone = %p\n", bp->b_iodone); 797 panic("bwrite: need chained iodone"); 798 } 799 800 /* get a new block */ 801 newbp = geteblk(bp->b_bufsize); 802 803 /* 804 * set it to be identical to the old block. We have to 805 * set b_lblkno and BKGRDMARKER before calling bgetvp() 806 * to avoid confusing the splay tree and gbincore(). 807 */ 808 memcpy(newbp->b_data, bp->b_data, bp->b_bufsize); 809 newbp->b_lblkno = bp->b_lblkno; 810 newbp->b_xflags |= BX_BKGRDMARKER; 811 bgetvp(bp->b_vp, newbp); 812 newbp->b_blkno = bp->b_blkno; 813 newbp->b_offset = bp->b_offset; 814 newbp->b_iodone = vfs_backgroundwritedone; 815 newbp->b_flags |= B_ASYNC; 816 newbp->b_flags &= ~B_INVAL; 817 818 /* move over the dependencies */ 819 if (LIST_FIRST(&bp->b_dep) != NULL) 820 buf_movedeps(bp, newbp); 821 822 /* 823 * Initiate write on the copy, release the original to 824 * the B_LOCKED queue so that it cannot go away until 825 * the background write completes. If not locked it could go 826 * away and then be reconstituted while it was being written. 827 * If the reconstituted buffer were written, we could end up 828 * with two background copies being written at the same time. 829 */ 830 bp->b_xflags |= BX_BKGRDINPROG; 831 bp->b_flags |= B_LOCKED; 832 bqrelse(bp); 833 bp = newbp; 834 } 835 836 bp->b_flags &= ~B_DONE; 837 bp->b_ioflags &= ~BIO_ERROR; 838 bp->b_flags |= B_WRITEINPROG | B_CACHE; 839 bp->b_iocmd = BIO_WRITE; 840 841 bp->b_vp->v_numoutput++; 842 vfs_busy_pages(bp, 1); 843 844 /* 845 * Normal bwrites pipeline writes 846 */ 847 bp->b_runningbufspace = bp->b_bufsize; 848 runningbufspace += bp->b_runningbufspace; 849 850 if (curthread != PCPU_GET(idlethread)) 851 curthread->td_proc->p_stats->p_ru.ru_oublock++; 852 splx(s); 853 if (oldflags & B_ASYNC) 854 BUF_KERNPROC(bp); 855 BUF_STRATEGY(bp); 856 857 if ((oldflags & B_ASYNC) == 0) { 858 int rtval = bufwait(bp); 859 brelse(bp); 860 return (rtval); 861 } else if ((oldflags & B_NOWDRAIN) == 0) { 862 /* 863 * don't allow the async write to saturate the I/O 864 * system. Deadlocks can occur only if a device strategy 865 * routine (like in MD) turns around and issues another 866 * high-level write, in which case B_NOWDRAIN is expected 867 * to be set. Otherwise we will not deadlock here because 868 * we are blocking waiting for I/O that is already in-progress 869 * to complete. 870 */ 871 waitrunningbufspace(); 872 } 873 874 return (0); 875} 876 877/* 878 * Complete a background write started from bwrite. 879 */ 880static void 881vfs_backgroundwritedone(bp) 882 struct buf *bp; 883{ 884 struct buf *origbp; 885 886 /* 887 * Find the original buffer that we are writing. 888 */ 889 if ((origbp = gbincore(bp->b_vp, bp->b_lblkno)) == NULL) 890 panic("backgroundwritedone: lost buffer"); 891 /* 892 * Process dependencies then return any unfinished ones. 893 */ 894 if (LIST_FIRST(&bp->b_dep) != NULL) 895 buf_complete(bp); 896 if (LIST_FIRST(&bp->b_dep) != NULL) 897 buf_movedeps(bp, origbp); 898 /* 899 * Clear the BX_BKGRDINPROG flag in the original buffer 900 * and awaken it if it is waiting for the write to complete. 901 * If BX_BKGRDINPROG is not set in the original buffer it must 902 * have been released and re-instantiated - which is not legal. 903 */ 904 KASSERT((origbp->b_xflags & BX_BKGRDINPROG), 905 ("backgroundwritedone: lost buffer2")); 906 origbp->b_xflags &= ~BX_BKGRDINPROG; 907 if (origbp->b_xflags & BX_BKGRDWAIT) { 908 origbp->b_xflags &= ~BX_BKGRDWAIT; 909 wakeup(&origbp->b_xflags); 910 } 911 /* 912 * Clear the B_LOCKED flag and remove it from the locked 913 * queue if it currently resides there. 914 */ 915 origbp->b_flags &= ~B_LOCKED; 916 if (BUF_LOCK(origbp, LK_EXCLUSIVE | LK_NOWAIT) == 0) { 917 bremfree(origbp); 918 bqrelse(origbp); 919 } 920 /* 921 * This buffer is marked B_NOCACHE, so when it is released 922 * by biodone, it will be tossed. We mark it with BIO_READ 923 * to avoid biodone doing a second vwakeup. 924 */ 925 bp->b_flags |= B_NOCACHE; 926 bp->b_iocmd = BIO_READ; 927 bp->b_flags &= ~(B_CACHE | B_DONE); 928 bp->b_iodone = 0; 929 bufdone(bp); 930} 931 932/* 933 * Delayed write. (Buffer is marked dirty). Do not bother writing 934 * anything if the buffer is marked invalid. 935 * 936 * Note that since the buffer must be completely valid, we can safely 937 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 938 * biodone() in order to prevent getblk from writing the buffer 939 * out synchronously. 940 */ 941void 942bdwrite(struct buf * bp) 943{ 944 GIANT_REQUIRED; 945 946 if (BUF_REFCNT(bp) == 0) 947 panic("bdwrite: buffer is not busy"); 948 949 if (bp->b_flags & B_INVAL) { 950 brelse(bp); 951 return; 952 } 953 bdirty(bp); 954 955 /* 956 * Set B_CACHE, indicating that the buffer is fully valid. This is 957 * true even of NFS now. 958 */ 959 bp->b_flags |= B_CACHE; 960 961 /* 962 * This bmap keeps the system from needing to do the bmap later, 963 * perhaps when the system is attempting to do a sync. Since it 964 * is likely that the indirect block -- or whatever other datastructure 965 * that the filesystem needs is still in memory now, it is a good 966 * thing to do this. Note also, that if the pageout daemon is 967 * requesting a sync -- there might not be enough memory to do 968 * the bmap then... So, this is important to do. 969 */ 970 if (bp->b_lblkno == bp->b_blkno) { 971 VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 972 } 973 974 /* 975 * Set the *dirty* buffer range based upon the VM system dirty pages. 976 */ 977 vfs_setdirty(bp); 978 979 /* 980 * We need to do this here to satisfy the vnode_pager and the 981 * pageout daemon, so that it thinks that the pages have been 982 * "cleaned". Note that since the pages are in a delayed write 983 * buffer -- the VFS layer "will" see that the pages get written 984 * out on the next sync, or perhaps the cluster will be completed. 985 */ 986 vfs_clean_pages(bp); 987 bqrelse(bp); 988 989 /* 990 * Wakeup the buffer flushing daemon if we have a lot of dirty 991 * buffers (midpoint between our recovery point and our stall 992 * point). 993 */ 994 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 995 996 /* 997 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 998 * due to the softdep code. 999 */ 1000} 1001 1002/* 1003 * bdirty: 1004 * 1005 * Turn buffer into delayed write request. We must clear BIO_READ and 1006 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 1007 * itself to properly update it in the dirty/clean lists. We mark it 1008 * B_DONE to ensure that any asynchronization of the buffer properly 1009 * clears B_DONE ( else a panic will occur later ). 1010 * 1011 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 1012 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 1013 * should only be called if the buffer is known-good. 1014 * 1015 * Since the buffer is not on a queue, we do not update the numfreebuffers 1016 * count. 1017 * 1018 * Must be called at splbio(). 1019 * The buffer must be on QUEUE_NONE. 1020 */ 1021void 1022bdirty(bp) 1023 struct buf *bp; 1024{ 1025 KASSERT(bp->b_qindex == QUEUE_NONE, 1026 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1027 bp->b_flags &= ~(B_RELBUF); 1028 bp->b_iocmd = BIO_WRITE; 1029 1030 if ((bp->b_flags & B_DELWRI) == 0) { 1031 bp->b_flags |= B_DONE | B_DELWRI; 1032 reassignbuf(bp, bp->b_vp); 1033 ++numdirtybuffers; 1034 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 1035 } 1036} 1037 1038/* 1039 * bundirty: 1040 * 1041 * Clear B_DELWRI for buffer. 1042 * 1043 * Since the buffer is not on a queue, we do not update the numfreebuffers 1044 * count. 1045 * 1046 * Must be called at splbio(). 1047 * The buffer must be on QUEUE_NONE. 1048 */ 1049 1050void 1051bundirty(bp) 1052 struct buf *bp; 1053{ 1054 KASSERT(bp->b_qindex == QUEUE_NONE, 1055 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1056 1057 if (bp->b_flags & B_DELWRI) { 1058 bp->b_flags &= ~B_DELWRI; 1059 reassignbuf(bp, bp->b_vp); 1060 --numdirtybuffers; 1061 numdirtywakeup(lodirtybuffers); 1062 } 1063 /* 1064 * Since it is now being written, we can clear its deferred write flag. 1065 */ 1066 bp->b_flags &= ~B_DEFERRED; 1067} 1068 1069/* 1070 * bawrite: 1071 * 1072 * Asynchronous write. Start output on a buffer, but do not wait for 1073 * it to complete. The buffer is released when the output completes. 1074 * 1075 * bwrite() ( or the VOP routine anyway ) is responsible for handling 1076 * B_INVAL buffers. Not us. 1077 */ 1078void 1079bawrite(struct buf * bp) 1080{ 1081 bp->b_flags |= B_ASYNC; 1082 (void) BUF_WRITE(bp); 1083} 1084 1085/* 1086 * bwillwrite: 1087 * 1088 * Called prior to the locking of any vnodes when we are expecting to 1089 * write. We do not want to starve the buffer cache with too many 1090 * dirty buffers so we block here. By blocking prior to the locking 1091 * of any vnodes we attempt to avoid the situation where a locked vnode 1092 * prevents the various system daemons from flushing related buffers. 1093 */ 1094 1095void 1096bwillwrite(void) 1097{ 1098 if (numdirtybuffers >= hidirtybuffers) { 1099 int s; 1100 1101 mtx_lock(&Giant); 1102 s = splbio(); 1103 while (numdirtybuffers >= hidirtybuffers) { 1104 bd_wakeup(1); 1105 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH; 1106 tsleep(&needsbuffer, (PRIBIO + 4), "flswai", 0); 1107 } 1108 splx(s); 1109 mtx_unlock(&Giant); 1110 } 1111} 1112 1113/* 1114 * Return true if we have too many dirty buffers. 1115 */ 1116int 1117buf_dirty_count_severe(void) 1118{ 1119 return(numdirtybuffers >= hidirtybuffers); 1120} 1121 1122/* 1123 * brelse: 1124 * 1125 * Release a busy buffer and, if requested, free its resources. The 1126 * buffer will be stashed in the appropriate bufqueue[] allowing it 1127 * to be accessed later as a cache entity or reused for other purposes. 1128 */ 1129void 1130brelse(struct buf * bp) 1131{ 1132 int s; 1133 1134 GIANT_REQUIRED; 1135 1136 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1137 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1138 1139 s = splbio(); 1140 1141 if (bp->b_flags & B_LOCKED) 1142 bp->b_ioflags &= ~BIO_ERROR; 1143 1144 if (bp->b_iocmd == BIO_WRITE && 1145 (bp->b_ioflags & BIO_ERROR) && 1146 !(bp->b_flags & B_INVAL)) { 1147 /* 1148 * Failed write, redirty. Must clear BIO_ERROR to prevent 1149 * pages from being scrapped. If B_INVAL is set then 1150 * this case is not run and the next case is run to 1151 * destroy the buffer. B_INVAL can occur if the buffer 1152 * is outside the range supported by the underlying device. 1153 */ 1154 bp->b_ioflags &= ~BIO_ERROR; 1155 bdirty(bp); 1156 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 1157 (bp->b_ioflags & BIO_ERROR) || 1158 bp->b_iocmd == BIO_DELETE || (bp->b_bufsize <= 0)) { 1159 /* 1160 * Either a failed I/O or we were asked to free or not 1161 * cache the buffer. 1162 */ 1163 bp->b_flags |= B_INVAL; 1164 if (LIST_FIRST(&bp->b_dep) != NULL) 1165 buf_deallocate(bp); 1166 if (bp->b_flags & B_DELWRI) { 1167 --numdirtybuffers; 1168 numdirtywakeup(lodirtybuffers); 1169 } 1170 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1171 if ((bp->b_flags & B_VMIO) == 0) { 1172 if (bp->b_bufsize) 1173 allocbuf(bp, 0); 1174 if (bp->b_vp) 1175 brelvp(bp); 1176 } 1177 } 1178 1179 /* 1180 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1181 * is called with B_DELWRI set, the underlying pages may wind up 1182 * getting freed causing a previous write (bdwrite()) to get 'lost' 1183 * because pages associated with a B_DELWRI bp are marked clean. 1184 * 1185 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1186 * if B_DELWRI is set. 1187 * 1188 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1189 * on pages to return pages to the VM page queues. 1190 */ 1191 if (bp->b_flags & B_DELWRI) 1192 bp->b_flags &= ~B_RELBUF; 1193 else if (vm_page_count_severe() && !(bp->b_xflags & BX_BKGRDINPROG)) 1194 bp->b_flags |= B_RELBUF; 1195 1196 /* 1197 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1198 * constituted, not even NFS buffers now. Two flags effect this. If 1199 * B_INVAL, the struct buf is invalidated but the VM object is kept 1200 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1201 * 1202 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 1203 * invalidated. BIO_ERROR cannot be set for a failed write unless the 1204 * buffer is also B_INVAL because it hits the re-dirtying code above. 1205 * 1206 * Normally we can do this whether a buffer is B_DELWRI or not. If 1207 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1208 * the commit state and we cannot afford to lose the buffer. If the 1209 * buffer has a background write in progress, we need to keep it 1210 * around to prevent it from being reconstituted and starting a second 1211 * background write. 1212 */ 1213 if ((bp->b_flags & B_VMIO) 1214 && !(bp->b_vp->v_mount != NULL && 1215 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 1216 !vn_isdisk(bp->b_vp, NULL) && 1217 (bp->b_flags & B_DELWRI)) 1218 ) { 1219 1220 int i, j, resid; 1221 vm_page_t m; 1222 off_t foff; 1223 vm_pindex_t poff; 1224 vm_object_t obj; 1225 struct vnode *vp; 1226 1227 vp = bp->b_vp; 1228 obj = bp->b_object; 1229 1230 /* 1231 * Get the base offset and length of the buffer. Note that 1232 * in the VMIO case if the buffer block size is not 1233 * page-aligned then b_data pointer may not be page-aligned. 1234 * But our b_pages[] array *IS* page aligned. 1235 * 1236 * block sizes less then DEV_BSIZE (usually 512) are not 1237 * supported due to the page granularity bits (m->valid, 1238 * m->dirty, etc...). 1239 * 1240 * See man buf(9) for more information 1241 */ 1242 resid = bp->b_bufsize; 1243 foff = bp->b_offset; 1244 1245 for (i = 0; i < bp->b_npages; i++) { 1246 int had_bogus = 0; 1247 1248 m = bp->b_pages[i]; 1249 vm_page_flag_clear(m, PG_ZERO); 1250 1251 /* 1252 * If we hit a bogus page, fixup *all* the bogus pages 1253 * now. 1254 */ 1255 if (m == bogus_page) { 1256 poff = OFF_TO_IDX(bp->b_offset); 1257 had_bogus = 1; 1258 1259 for (j = i; j < bp->b_npages; j++) { 1260 vm_page_t mtmp; 1261 mtmp = bp->b_pages[j]; 1262 if (mtmp == bogus_page) { 1263 mtmp = vm_page_lookup(obj, poff + j); 1264 if (!mtmp) { 1265 panic("brelse: page missing\n"); 1266 } 1267 bp->b_pages[j] = mtmp; 1268 } 1269 } 1270 1271 if ((bp->b_flags & B_INVAL) == 0) { 1272 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 1273 } 1274 m = bp->b_pages[i]; 1275 } 1276 if ((bp->b_flags & B_NOCACHE) || (bp->b_ioflags & BIO_ERROR)) { 1277 int poffset = foff & PAGE_MASK; 1278 int presid = resid > (PAGE_SIZE - poffset) ? 1279 (PAGE_SIZE - poffset) : resid; 1280 1281 KASSERT(presid >= 0, ("brelse: extra page")); 1282 vm_page_set_invalid(m, poffset, presid); 1283 if (had_bogus) 1284 printf("avoided corruption bug in bogus_page/brelse code\n"); 1285 } 1286 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1287 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1288 } 1289 1290 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1291 vfs_vmio_release(bp); 1292 1293 } else if (bp->b_flags & B_VMIO) { 1294 1295 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1296 vfs_vmio_release(bp); 1297 } 1298 1299 } 1300 1301 if (bp->b_qindex != QUEUE_NONE) 1302 panic("brelse: free buffer onto another queue???"); 1303 if (BUF_REFCNT(bp) > 1) { 1304 /* do not release to free list */ 1305 BUF_UNLOCK(bp); 1306 splx(s); 1307 return; 1308 } 1309 1310 /* enqueue */ 1311 1312 /* buffers with no memory */ 1313 if (bp->b_bufsize == 0) { 1314 bp->b_flags |= B_INVAL; 1315 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1316 if (bp->b_xflags & BX_BKGRDINPROG) 1317 panic("losing buffer 1"); 1318 if (bp->b_kvasize) { 1319 bp->b_qindex = QUEUE_EMPTYKVA; 1320 } else { 1321 bp->b_qindex = QUEUE_EMPTY; 1322 } 1323 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1324#ifdef USE_BUFHASH 1325 LIST_REMOVE(bp, b_hash); 1326 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1327#endif 1328 bp->b_dev = NODEV; 1329 /* buffers with junk contents */ 1330 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 1331 (bp->b_ioflags & BIO_ERROR)) { 1332 bp->b_flags |= B_INVAL; 1333 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1334 if (bp->b_xflags & BX_BKGRDINPROG) 1335 panic("losing buffer 2"); 1336 bp->b_qindex = QUEUE_CLEAN; 1337 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1338#ifdef USE_BUFHASH 1339 LIST_REMOVE(bp, b_hash); 1340 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1341#endif 1342 bp->b_dev = NODEV; 1343 1344 /* buffers that are locked */ 1345 } else if (bp->b_flags & B_LOCKED) { 1346 bp->b_qindex = QUEUE_LOCKED; 1347 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LOCKED], bp, b_freelist); 1348 1349 /* remaining buffers */ 1350 } else { 1351 if (bp->b_flags & B_DELWRI) 1352 bp->b_qindex = QUEUE_DIRTY; 1353 else 1354 bp->b_qindex = QUEUE_CLEAN; 1355 if (bp->b_flags & B_AGE) 1356 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1357 else 1358 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1359 } 1360 1361 /* 1362 * If B_INVAL and B_DELWRI is set, clear B_DELWRI. We have already 1363 * placed the buffer on the correct queue. We must also disassociate 1364 * the device and vnode for a B_INVAL buffer so gbincore() doesn't 1365 * find it. 1366 */ 1367 if (bp->b_flags & B_INVAL) { 1368 if (bp->b_flags & B_DELWRI) 1369 bundirty(bp); 1370 if (bp->b_vp) 1371 brelvp(bp); 1372 } 1373 1374 /* 1375 * Fixup numfreebuffers count. The bp is on an appropriate queue 1376 * unless locked. We then bump numfreebuffers if it is not B_DELWRI. 1377 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1378 * if B_INVAL is set ). 1379 */ 1380 1381 if ((bp->b_flags & B_LOCKED) == 0 && !(bp->b_flags & B_DELWRI)) 1382 bufcountwakeup(); 1383 1384 /* 1385 * Something we can maybe free or reuse 1386 */ 1387 if (bp->b_bufsize || bp->b_kvasize) 1388 bufspacewakeup(); 1389 1390 /* unlock */ 1391 BUF_UNLOCK(bp); 1392 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | 1393 B_DIRECT | B_NOWDRAIN); 1394 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1395 panic("brelse: not dirty"); 1396 splx(s); 1397} 1398 1399/* 1400 * Release a buffer back to the appropriate queue but do not try to free 1401 * it. The buffer is expected to be used again soon. 1402 * 1403 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1404 * biodone() to requeue an async I/O on completion. It is also used when 1405 * known good buffers need to be requeued but we think we may need the data 1406 * again soon. 1407 * 1408 * XXX we should be able to leave the B_RELBUF hint set on completion. 1409 */ 1410void 1411bqrelse(struct buf * bp) 1412{ 1413 int s; 1414 1415 s = splbio(); 1416 1417 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1418 1419 if (bp->b_qindex != QUEUE_NONE) 1420 panic("bqrelse: free buffer onto another queue???"); 1421 if (BUF_REFCNT(bp) > 1) { 1422 /* do not release to free list */ 1423 BUF_UNLOCK(bp); 1424 splx(s); 1425 return; 1426 } 1427 if (bp->b_flags & B_LOCKED) { 1428 bp->b_ioflags &= ~BIO_ERROR; 1429 bp->b_qindex = QUEUE_LOCKED; 1430 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LOCKED], bp, b_freelist); 1431 /* buffers with stale but valid contents */ 1432 } else if (bp->b_flags & B_DELWRI) { 1433 bp->b_qindex = QUEUE_DIRTY; 1434 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist); 1435 } else if (vm_page_count_severe()) { 1436 /* 1437 * We are too low on memory, we have to try to free the 1438 * buffer (most importantly: the wired pages making up its 1439 * backing store) *now*. 1440 */ 1441 splx(s); 1442 brelse(bp); 1443 return; 1444 } else { 1445 bp->b_qindex = QUEUE_CLEAN; 1446 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1447 } 1448 1449 if ((bp->b_flags & B_LOCKED) == 0 && 1450 ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI))) { 1451 bufcountwakeup(); 1452 } 1453 1454 /* 1455 * Something we can maybe free or reuse. 1456 */ 1457 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1458 bufspacewakeup(); 1459 1460 /* unlock */ 1461 BUF_UNLOCK(bp); 1462 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1463 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1464 panic("bqrelse: not dirty"); 1465 splx(s); 1466} 1467 1468/* Give pages used by the bp back to the VM system (where possible) */ 1469static void 1470vfs_vmio_release(bp) 1471 struct buf *bp; 1472{ 1473 int i; 1474 vm_page_t m; 1475 1476 GIANT_REQUIRED; 1477 vm_page_lock_queues(); 1478 for (i = 0; i < bp->b_npages; i++) { 1479 m = bp->b_pages[i]; 1480 bp->b_pages[i] = NULL; 1481 /* 1482 * In order to keep page LRU ordering consistent, put 1483 * everything on the inactive queue. 1484 */ 1485 vm_page_unwire(m, 0); 1486 /* 1487 * We don't mess with busy pages, it is 1488 * the responsibility of the process that 1489 * busied the pages to deal with them. 1490 */ 1491 if ((m->flags & PG_BUSY) || (m->busy != 0)) 1492 continue; 1493 1494 if (m->wire_count == 0) { 1495 vm_page_flag_clear(m, PG_ZERO); 1496 /* 1497 * Might as well free the page if we can and it has 1498 * no valid data. We also free the page if the 1499 * buffer was used for direct I/O 1500 */ 1501 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && 1502 m->hold_count == 0) { 1503 vm_page_busy(m); 1504 vm_page_protect(m, VM_PROT_NONE); 1505 vm_page_free(m); 1506 } else if (bp->b_flags & B_DIRECT) { 1507 vm_page_try_to_free(m); 1508 } else if (vm_page_count_severe()) { 1509 vm_page_try_to_cache(m); 1510 } 1511 } 1512 } 1513 vm_page_unlock_queues(); 1514 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages); 1515 1516 if (bp->b_bufsize) { 1517 bufspacewakeup(); 1518 bp->b_bufsize = 0; 1519 } 1520 bp->b_npages = 0; 1521 bp->b_flags &= ~B_VMIO; 1522 if (bp->b_vp) 1523 brelvp(bp); 1524} 1525 1526#ifdef USE_BUFHASH 1527/* 1528 * XXX MOVED TO VFS_SUBR.C 1529 * 1530 * Check to see if a block is currently memory resident. 1531 */ 1532struct buf * 1533gbincore(struct vnode * vp, daddr_t blkno) 1534{ 1535 struct buf *bp; 1536 struct bufhashhdr *bh; 1537 1538 bh = bufhash(vp, blkno); 1539 1540 /* Search hash chain */ 1541 LIST_FOREACH(bp, bh, b_hash) { 1542 /* hit */ 1543 if (bp->b_vp == vp && bp->b_lblkno == blkno && 1544 (bp->b_flags & B_INVAL) == 0) { 1545 break; 1546 } 1547 } 1548 return (bp); 1549} 1550#endif 1551 1552/* 1553 * vfs_bio_awrite: 1554 * 1555 * Implement clustered async writes for clearing out B_DELWRI buffers. 1556 * This is much better then the old way of writing only one buffer at 1557 * a time. Note that we may not be presented with the buffers in the 1558 * correct order, so we search for the cluster in both directions. 1559 */ 1560int 1561vfs_bio_awrite(struct buf * bp) 1562{ 1563 int i; 1564 int j; 1565 daddr_t lblkno = bp->b_lblkno; 1566 struct vnode *vp = bp->b_vp; 1567 int s; 1568 int ncl; 1569 struct buf *bpa; 1570 int nwritten; 1571 int size; 1572 int maxcl; 1573 1574 s = splbio(); 1575 /* 1576 * right now we support clustered writing only to regular files. If 1577 * we find a clusterable block we could be in the middle of a cluster 1578 * rather then at the beginning. 1579 */ 1580 if ((vp->v_type == VREG) && 1581 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1582 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1583 1584 size = vp->v_mount->mnt_stat.f_iosize; 1585 maxcl = MAXPHYS / size; 1586 1587 for (i = 1; i < maxcl; i++) { 1588 if ((bpa = gbincore(vp, lblkno + i)) && 1589 BUF_REFCNT(bpa) == 0 && 1590 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == 1591 (B_DELWRI | B_CLUSTEROK)) && 1592 (bpa->b_bufsize == size)) { 1593 if ((bpa->b_blkno == bpa->b_lblkno) || 1594 (bpa->b_blkno != 1595 bp->b_blkno + ((i * size) >> DEV_BSHIFT))) 1596 break; 1597 } else { 1598 break; 1599 } 1600 } 1601 for (j = 1; i + j <= maxcl && j <= lblkno; j++) { 1602 if ((bpa = gbincore(vp, lblkno - j)) && 1603 BUF_REFCNT(bpa) == 0 && 1604 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == 1605 (B_DELWRI | B_CLUSTEROK)) && 1606 (bpa->b_bufsize == size)) { 1607 if ((bpa->b_blkno == bpa->b_lblkno) || 1608 (bpa->b_blkno != 1609 bp->b_blkno - ((j * size) >> DEV_BSHIFT))) 1610 break; 1611 } else { 1612 break; 1613 } 1614 } 1615 --j; 1616 ncl = i + j; 1617 /* 1618 * this is a possible cluster write 1619 */ 1620 if (ncl != 1) { 1621 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl); 1622 splx(s); 1623 return nwritten; 1624 } 1625 } 1626 1627 BUF_LOCK(bp, LK_EXCLUSIVE); 1628 bremfree(bp); 1629 bp->b_flags |= B_ASYNC; 1630 1631 splx(s); 1632 /* 1633 * default (old) behavior, writing out only one block 1634 * 1635 * XXX returns b_bufsize instead of b_bcount for nwritten? 1636 */ 1637 nwritten = bp->b_bufsize; 1638 (void) BUF_WRITE(bp); 1639 1640 return nwritten; 1641} 1642 1643/* 1644 * getnewbuf: 1645 * 1646 * Find and initialize a new buffer header, freeing up existing buffers 1647 * in the bufqueues as necessary. The new buffer is returned locked. 1648 * 1649 * Important: B_INVAL is not set. If the caller wishes to throw the 1650 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1651 * 1652 * We block if: 1653 * We have insufficient buffer headers 1654 * We have insufficient buffer space 1655 * buffer_map is too fragmented ( space reservation fails ) 1656 * If we have to flush dirty buffers ( but we try to avoid this ) 1657 * 1658 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1659 * Instead we ask the buf daemon to do it for us. We attempt to 1660 * avoid piecemeal wakeups of the pageout daemon. 1661 */ 1662 1663static struct buf * 1664getnewbuf(int slpflag, int slptimeo, int size, int maxsize) 1665{ 1666 struct buf *bp; 1667 struct buf *nbp; 1668 int defrag = 0; 1669 int nqindex; 1670 static int flushingbufs; 1671 1672 GIANT_REQUIRED; 1673 1674 /* 1675 * We can't afford to block since we might be holding a vnode lock, 1676 * which may prevent system daemons from running. We deal with 1677 * low-memory situations by proactively returning memory and running 1678 * async I/O rather then sync I/O. 1679 */ 1680 1681 ++getnewbufcalls; 1682 --getnewbufrestarts; 1683restart: 1684 ++getnewbufrestarts; 1685 1686 /* 1687 * Setup for scan. If we do not have enough free buffers, 1688 * we setup a degenerate case that immediately fails. Note 1689 * that if we are specially marked process, we are allowed to 1690 * dip into our reserves. 1691 * 1692 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 1693 * 1694 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 1695 * However, there are a number of cases (defragging, reusing, ...) 1696 * where we cannot backup. 1697 */ 1698 nqindex = QUEUE_EMPTYKVA; 1699 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 1700 1701 if (nbp == NULL) { 1702 /* 1703 * If no EMPTYKVA buffers and we are either 1704 * defragging or reusing, locate a CLEAN buffer 1705 * to free or reuse. If bufspace useage is low 1706 * skip this step so we can allocate a new buffer. 1707 */ 1708 if (defrag || bufspace >= lobufspace) { 1709 nqindex = QUEUE_CLEAN; 1710 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 1711 } 1712 1713 /* 1714 * If we could not find or were not allowed to reuse a 1715 * CLEAN buffer, check to see if it is ok to use an EMPTY 1716 * buffer. We can only use an EMPTY buffer if allocating 1717 * its KVA would not otherwise run us out of buffer space. 1718 */ 1719 if (nbp == NULL && defrag == 0 && 1720 bufspace + maxsize < hibufspace) { 1721 nqindex = QUEUE_EMPTY; 1722 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1723 } 1724 } 1725 1726 /* 1727 * Run scan, possibly freeing data and/or kva mappings on the fly 1728 * depending. 1729 */ 1730 1731 while ((bp = nbp) != NULL) { 1732 int qindex = nqindex; 1733 1734 /* 1735 * Calculate next bp ( we can only use it if we do not block 1736 * or do other fancy things ). 1737 */ 1738 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 1739 switch(qindex) { 1740 case QUEUE_EMPTY: 1741 nqindex = QUEUE_EMPTYKVA; 1742 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]))) 1743 break; 1744 /* FALLTHROUGH */ 1745 case QUEUE_EMPTYKVA: 1746 nqindex = QUEUE_CLEAN; 1747 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]))) 1748 break; 1749 /* FALLTHROUGH */ 1750 case QUEUE_CLEAN: 1751 /* 1752 * nbp is NULL. 1753 */ 1754 break; 1755 } 1756 } 1757 1758 /* 1759 * Sanity Checks 1760 */ 1761 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp)); 1762 1763 /* 1764 * Note: we no longer distinguish between VMIO and non-VMIO 1765 * buffers. 1766 */ 1767 1768 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); 1769 1770 /* 1771 * If we are defragging then we need a buffer with 1772 * b_kvasize != 0. XXX this situation should no longer 1773 * occur, if defrag is non-zero the buffer's b_kvasize 1774 * should also be non-zero at this point. XXX 1775 */ 1776 if (defrag && bp->b_kvasize == 0) { 1777 printf("Warning: defrag empty buffer %p\n", bp); 1778 continue; 1779 } 1780 1781 /* 1782 * Start freeing the bp. This is somewhat involved. nbp 1783 * remains valid only for QUEUE_EMPTY[KVA] bp's. 1784 */ 1785 1786 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) 1787 panic("getnewbuf: locked buf"); 1788 bremfree(bp); 1789 1790 if (qindex == QUEUE_CLEAN) { 1791 if (bp->b_flags & B_VMIO) { 1792 bp->b_flags &= ~B_ASYNC; 1793 vfs_vmio_release(bp); 1794 } 1795 if (bp->b_vp) 1796 brelvp(bp); 1797 } 1798 1799 /* 1800 * NOTE: nbp is now entirely invalid. We can only restart 1801 * the scan from this point on. 1802 * 1803 * Get the rest of the buffer freed up. b_kva* is still 1804 * valid after this operation. 1805 */ 1806 1807 if (bp->b_rcred != NOCRED) { 1808 crfree(bp->b_rcred); 1809 bp->b_rcred = NOCRED; 1810 } 1811 if (bp->b_wcred != NOCRED) { 1812 crfree(bp->b_wcred); 1813 bp->b_wcred = NOCRED; 1814 } 1815 if (LIST_FIRST(&bp->b_dep) != NULL) 1816 buf_deallocate(bp); 1817 if (bp->b_xflags & BX_BKGRDINPROG) 1818 panic("losing buffer 3"); 1819#ifdef USE_BUFHASH 1820 LIST_REMOVE(bp, b_hash); 1821 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1822#endif 1823 1824 if (bp->b_bufsize) 1825 allocbuf(bp, 0); 1826 1827 bp->b_flags = 0; 1828 bp->b_ioflags = 0; 1829 bp->b_xflags = 0; 1830 bp->b_dev = NODEV; 1831 bp->b_vp = NULL; 1832 bp->b_blkno = bp->b_lblkno = 0; 1833 bp->b_offset = NOOFFSET; 1834 bp->b_iodone = 0; 1835 bp->b_error = 0; 1836 bp->b_resid = 0; 1837 bp->b_bcount = 0; 1838 bp->b_npages = 0; 1839 bp->b_dirtyoff = bp->b_dirtyend = 0; 1840 bp->b_magic = B_MAGIC_BIO; 1841 bp->b_op = &buf_ops_bio; 1842 bp->b_object = NULL; 1843 1844 LIST_INIT(&bp->b_dep); 1845 1846 /* 1847 * If we are defragging then free the buffer. 1848 */ 1849 if (defrag) { 1850 bp->b_flags |= B_INVAL; 1851 bfreekva(bp); 1852 brelse(bp); 1853 defrag = 0; 1854 goto restart; 1855 } 1856 1857 /* 1858 * If we are overcomitted then recover the buffer and its 1859 * KVM space. This occurs in rare situations when multiple 1860 * processes are blocked in getnewbuf() or allocbuf(). 1861 */ 1862 if (bufspace >= hibufspace) 1863 flushingbufs = 1; 1864 if (flushingbufs && bp->b_kvasize != 0) { 1865 bp->b_flags |= B_INVAL; 1866 bfreekva(bp); 1867 brelse(bp); 1868 goto restart; 1869 } 1870 if (bufspace < lobufspace) 1871 flushingbufs = 0; 1872 break; 1873 } 1874 1875 /* 1876 * If we exhausted our list, sleep as appropriate. We may have to 1877 * wakeup various daemons and write out some dirty buffers. 1878 * 1879 * Generally we are sleeping due to insufficient buffer space. 1880 */ 1881 1882 if (bp == NULL) { 1883 int flags; 1884 char *waitmsg; 1885 1886 if (defrag) { 1887 flags = VFS_BIO_NEED_BUFSPACE; 1888 waitmsg = "nbufkv"; 1889 } else if (bufspace >= hibufspace) { 1890 waitmsg = "nbufbs"; 1891 flags = VFS_BIO_NEED_BUFSPACE; 1892 } else { 1893 waitmsg = "newbuf"; 1894 flags = VFS_BIO_NEED_ANY; 1895 } 1896 1897 bd_speedup(); /* heeeelp */ 1898 1899 needsbuffer |= flags; 1900 while (needsbuffer & flags) { 1901 if (tsleep(&needsbuffer, (PRIBIO + 4) | slpflag, 1902 waitmsg, slptimeo)) 1903 return (NULL); 1904 } 1905 } else { 1906 /* 1907 * We finally have a valid bp. We aren't quite out of the 1908 * woods, we still have to reserve kva space. In order 1909 * to keep fragmentation sane we only allocate kva in 1910 * BKVASIZE chunks. 1911 */ 1912 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 1913 1914 if (maxsize != bp->b_kvasize) { 1915 vm_offset_t addr = 0; 1916 1917 bfreekva(bp); 1918 1919 if (vm_map_findspace(buffer_map, 1920 vm_map_min(buffer_map), maxsize, &addr)) { 1921 /* 1922 * Uh oh. Buffer map is to fragmented. We 1923 * must defragment the map. 1924 */ 1925 ++bufdefragcnt; 1926 defrag = 1; 1927 bp->b_flags |= B_INVAL; 1928 brelse(bp); 1929 goto restart; 1930 } 1931 if (addr) { 1932 vm_map_insert(buffer_map, NULL, 0, 1933 addr, addr + maxsize, 1934 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT); 1935 1936 bp->b_kvabase = (caddr_t) addr; 1937 bp->b_kvasize = maxsize; 1938 bufspace += bp->b_kvasize; 1939 ++bufreusecnt; 1940 } 1941 } 1942 bp->b_data = bp->b_kvabase; 1943 } 1944 return(bp); 1945} 1946 1947/* 1948 * buf_daemon: 1949 * 1950 * buffer flushing daemon. Buffers are normally flushed by the 1951 * update daemon but if it cannot keep up this process starts to 1952 * take the load in an attempt to prevent getnewbuf() from blocking. 1953 */ 1954 1955static struct proc *bufdaemonproc; 1956 1957static struct kproc_desc buf_kp = { 1958 "bufdaemon", 1959 buf_daemon, 1960 &bufdaemonproc 1961}; 1962SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp) 1963 1964static void 1965buf_daemon() 1966{ 1967 int s; 1968 1969 mtx_lock(&Giant); 1970 1971 /* 1972 * This process needs to be suspended prior to shutdown sync. 1973 */ 1974 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 1975 SHUTDOWN_PRI_LAST); 1976 1977 /* 1978 * This process is allowed to take the buffer cache to the limit 1979 */ 1980 s = splbio(); 1981 1982 for (;;) { 1983 kthread_suspend_check(bufdaemonproc); 1984 1985 bd_request = 0; 1986 1987 /* 1988 * Do the flush. Limit the amount of in-transit I/O we 1989 * allow to build up, otherwise we would completely saturate 1990 * the I/O system. Wakeup any waiting processes before we 1991 * normally would so they can run in parallel with our drain. 1992 */ 1993 while (numdirtybuffers > lodirtybuffers) { 1994 if (flushbufqueues() == 0) 1995 break; 1996 waitrunningbufspace(); 1997 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 1998 } 1999 2000 /* 2001 * Only clear bd_request if we have reached our low water 2002 * mark. The buf_daemon normally waits 1 second and 2003 * then incrementally flushes any dirty buffers that have 2004 * built up, within reason. 2005 * 2006 * If we were unable to hit our low water mark and couldn't 2007 * find any flushable buffers, we sleep half a second. 2008 * Otherwise we loop immediately. 2009 */ 2010 if (numdirtybuffers <= lodirtybuffers) { 2011 /* 2012 * We reached our low water mark, reset the 2013 * request and sleep until we are needed again. 2014 * The sleep is just so the suspend code works. 2015 */ 2016 bd_request = 0; 2017 tsleep(&bd_request, PVM, "psleep", hz); 2018 } else { 2019 /* 2020 * We couldn't find any flushable dirty buffers but 2021 * still have too many dirty buffers, we 2022 * have to sleep and try again. (rare) 2023 */ 2024 tsleep(&bd_request, PVM, "qsleep", hz / 2); 2025 } 2026 } 2027} 2028 2029/* 2030 * flushbufqueues: 2031 * 2032 * Try to flush a buffer in the dirty queue. We must be careful to 2033 * free up B_INVAL buffers instead of write them, which NFS is 2034 * particularly sensitive to. 2035 */ 2036 2037static int 2038flushbufqueues(void) 2039{ 2040 struct buf *bp; 2041 int r = 0; 2042 2043 bp = TAILQ_FIRST(&bufqueues[QUEUE_DIRTY]); 2044 2045 while (bp) { 2046 KASSERT((bp->b_flags & B_DELWRI), ("unexpected clean buffer %p", bp)); 2047 if ((bp->b_flags & B_DELWRI) != 0 && 2048 (bp->b_xflags & BX_BKGRDINPROG) == 0) { 2049 if (bp->b_flags & B_INVAL) { 2050 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) 2051 panic("flushbufqueues: locked buf"); 2052 bremfree(bp); 2053 brelse(bp); 2054 ++r; 2055 break; 2056 } 2057 if (LIST_FIRST(&bp->b_dep) != NULL && 2058 (bp->b_flags & B_DEFERRED) == 0 && 2059 buf_countdeps(bp, 0)) { 2060 TAILQ_REMOVE(&bufqueues[QUEUE_DIRTY], 2061 bp, b_freelist); 2062 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], 2063 bp, b_freelist); 2064 bp->b_flags |= B_DEFERRED; 2065 bp = TAILQ_FIRST(&bufqueues[QUEUE_DIRTY]); 2066 continue; 2067 } 2068 vfs_bio_awrite(bp); 2069 ++r; 2070 break; 2071 } 2072 bp = TAILQ_NEXT(bp, b_freelist); 2073 } 2074 return (r); 2075} 2076 2077/* 2078 * Check to see if a block is currently memory resident. 2079 */ 2080struct buf * 2081incore(struct vnode * vp, daddr_t blkno) 2082{ 2083 struct buf *bp; 2084 2085 int s = splbio(); 2086 bp = gbincore(vp, blkno); 2087 splx(s); 2088 return (bp); 2089} 2090 2091/* 2092 * Returns true if no I/O is needed to access the 2093 * associated VM object. This is like incore except 2094 * it also hunts around in the VM system for the data. 2095 */ 2096 2097int 2098inmem(struct vnode * vp, daddr_t blkno) 2099{ 2100 vm_object_t obj; 2101 vm_offset_t toff, tinc, size; 2102 vm_page_t m; 2103 vm_ooffset_t off; 2104 2105 GIANT_REQUIRED; 2106 2107 if (incore(vp, blkno)) 2108 return 1; 2109 if (vp->v_mount == NULL) 2110 return 0; 2111 if (VOP_GETVOBJECT(vp, &obj) != 0 || (vp->v_vflag & VV_OBJBUF) == 0) 2112 return 0; 2113 2114 size = PAGE_SIZE; 2115 if (size > vp->v_mount->mnt_stat.f_iosize) 2116 size = vp->v_mount->mnt_stat.f_iosize; 2117 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2118 2119 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2120 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2121 if (!m) 2122 goto notinmem; 2123 tinc = size; 2124 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2125 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2126 if (vm_page_is_valid(m, 2127 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2128 goto notinmem; 2129 } 2130 return 1; 2131 2132notinmem: 2133 return (0); 2134} 2135 2136/* 2137 * vfs_setdirty: 2138 * 2139 * Sets the dirty range for a buffer based on the status of the dirty 2140 * bits in the pages comprising the buffer. 2141 * 2142 * The range is limited to the size of the buffer. 2143 * 2144 * This routine is primarily used by NFS, but is generalized for the 2145 * B_VMIO case. 2146 */ 2147static void 2148vfs_setdirty(struct buf *bp) 2149{ 2150 int i; 2151 vm_object_t object; 2152 2153 GIANT_REQUIRED; 2154 /* 2155 * Degenerate case - empty buffer 2156 */ 2157 2158 if (bp->b_bufsize == 0) 2159 return; 2160 2161 /* 2162 * We qualify the scan for modified pages on whether the 2163 * object has been flushed yet. The OBJ_WRITEABLE flag 2164 * is not cleared simply by protecting pages off. 2165 */ 2166 2167 if ((bp->b_flags & B_VMIO) == 0) 2168 return; 2169 2170 object = bp->b_pages[0]->object; 2171 2172 if ((object->flags & OBJ_WRITEABLE) && !(object->flags & OBJ_MIGHTBEDIRTY)) 2173 printf("Warning: object %p writeable but not mightbedirty\n", object); 2174 if (!(object->flags & OBJ_WRITEABLE) && (object->flags & OBJ_MIGHTBEDIRTY)) 2175 printf("Warning: object %p mightbedirty but not writeable\n", object); 2176 2177 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) { 2178 vm_offset_t boffset; 2179 vm_offset_t eoffset; 2180 2181 /* 2182 * test the pages to see if they have been modified directly 2183 * by users through the VM system. 2184 */ 2185 for (i = 0; i < bp->b_npages; i++) { 2186 vm_page_flag_clear(bp->b_pages[i], PG_ZERO); 2187 vm_page_test_dirty(bp->b_pages[i]); 2188 } 2189 2190 /* 2191 * Calculate the encompassing dirty range, boffset and eoffset, 2192 * (eoffset - boffset) bytes. 2193 */ 2194 2195 for (i = 0; i < bp->b_npages; i++) { 2196 if (bp->b_pages[i]->dirty) 2197 break; 2198 } 2199 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2200 2201 for (i = bp->b_npages - 1; i >= 0; --i) { 2202 if (bp->b_pages[i]->dirty) { 2203 break; 2204 } 2205 } 2206 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2207 2208 /* 2209 * Fit it to the buffer. 2210 */ 2211 2212 if (eoffset > bp->b_bcount) 2213 eoffset = bp->b_bcount; 2214 2215 /* 2216 * If we have a good dirty range, merge with the existing 2217 * dirty range. 2218 */ 2219 2220 if (boffset < eoffset) { 2221 if (bp->b_dirtyoff > boffset) 2222 bp->b_dirtyoff = boffset; 2223 if (bp->b_dirtyend < eoffset) 2224 bp->b_dirtyend = eoffset; 2225 } 2226 } 2227} 2228 2229/* 2230 * getblk: 2231 * 2232 * Get a block given a specified block and offset into a file/device. 2233 * The buffers B_DONE bit will be cleared on return, making it almost 2234 * ready for an I/O initiation. B_INVAL may or may not be set on 2235 * return. The caller should clear B_INVAL prior to initiating a 2236 * READ. 2237 * 2238 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2239 * an existing buffer. 2240 * 2241 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2242 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2243 * and then cleared based on the backing VM. If the previous buffer is 2244 * non-0-sized but invalid, B_CACHE will be cleared. 2245 * 2246 * If getblk() must create a new buffer, the new buffer is returned with 2247 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2248 * case it is returned with B_INVAL clear and B_CACHE set based on the 2249 * backing VM. 2250 * 2251 * getblk() also forces a BUF_WRITE() for any B_DELWRI buffer whos 2252 * B_CACHE bit is clear. 2253 * 2254 * What this means, basically, is that the caller should use B_CACHE to 2255 * determine whether the buffer is fully valid or not and should clear 2256 * B_INVAL prior to issuing a read. If the caller intends to validate 2257 * the buffer by loading its data area with something, the caller needs 2258 * to clear B_INVAL. If the caller does this without issuing an I/O, 2259 * the caller should set B_CACHE ( as an optimization ), else the caller 2260 * should issue the I/O and biodone() will set B_CACHE if the I/O was 2261 * a write attempt or if it was a successfull read. If the caller 2262 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 2263 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 2264 */ 2265struct buf * 2266getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo) 2267{ 2268 struct buf *bp; 2269 int s; 2270#ifdef USE_BUFHASH 2271 struct bufhashhdr *bh; 2272#endif 2273 2274 if (size > MAXBSIZE) 2275 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 2276 2277 s = splbio(); 2278loop: 2279 /* 2280 * Block if we are low on buffers. Certain processes are allowed 2281 * to completely exhaust the buffer cache. 2282 * 2283 * If this check ever becomes a bottleneck it may be better to 2284 * move it into the else, when gbincore() fails. At the moment 2285 * it isn't a problem. 2286 * 2287 * XXX remove if 0 sections (clean this up after its proven) 2288 */ 2289 if (numfreebuffers == 0) { 2290 if (curthread == PCPU_GET(idlethread)) 2291 return NULL; 2292 needsbuffer |= VFS_BIO_NEED_ANY; 2293 } 2294 2295 if ((bp = gbincore(vp, blkno))) { 2296 /* 2297 * Buffer is in-core. If the buffer is not busy, it must 2298 * be on a queue. 2299 */ 2300 2301 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) { 2302 if (BUF_TIMELOCK(bp, LK_EXCLUSIVE | LK_SLEEPFAIL, 2303 "getblk", slpflag, slptimeo) == ENOLCK) 2304 goto loop; 2305 splx(s); 2306 return (struct buf *) NULL; 2307 } 2308 2309 /* 2310 * The buffer is locked. B_CACHE is cleared if the buffer is 2311 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 2312 * and for a VMIO buffer B_CACHE is adjusted according to the 2313 * backing VM cache. 2314 */ 2315 if (bp->b_flags & B_INVAL) 2316 bp->b_flags &= ~B_CACHE; 2317 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 2318 bp->b_flags |= B_CACHE; 2319 bremfree(bp); 2320 2321 /* 2322 * check for size inconsistancies for non-VMIO case. 2323 */ 2324 2325 if (bp->b_bcount != size) { 2326 if ((bp->b_flags & B_VMIO) == 0 || 2327 (size > bp->b_kvasize)) { 2328 if (bp->b_flags & B_DELWRI) { 2329 bp->b_flags |= B_NOCACHE; 2330 BUF_WRITE(bp); 2331 } else { 2332 if ((bp->b_flags & B_VMIO) && 2333 (LIST_FIRST(&bp->b_dep) == NULL)) { 2334 bp->b_flags |= B_RELBUF; 2335 brelse(bp); 2336 } else { 2337 bp->b_flags |= B_NOCACHE; 2338 BUF_WRITE(bp); 2339 } 2340 } 2341 goto loop; 2342 } 2343 } 2344 2345 /* 2346 * If the size is inconsistant in the VMIO case, we can resize 2347 * the buffer. This might lead to B_CACHE getting set or 2348 * cleared. If the size has not changed, B_CACHE remains 2349 * unchanged from its previous state. 2350 */ 2351 2352 if (bp->b_bcount != size) 2353 allocbuf(bp, size); 2354 2355 KASSERT(bp->b_offset != NOOFFSET, 2356 ("getblk: no buffer offset")); 2357 2358 /* 2359 * A buffer with B_DELWRI set and B_CACHE clear must 2360 * be committed before we can return the buffer in 2361 * order to prevent the caller from issuing a read 2362 * ( due to B_CACHE not being set ) and overwriting 2363 * it. 2364 * 2365 * Most callers, including NFS and FFS, need this to 2366 * operate properly either because they assume they 2367 * can issue a read if B_CACHE is not set, or because 2368 * ( for example ) an uncached B_DELWRI might loop due 2369 * to softupdates re-dirtying the buffer. In the latter 2370 * case, B_CACHE is set after the first write completes, 2371 * preventing further loops. 2372 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 2373 * above while extending the buffer, we cannot allow the 2374 * buffer to remain with B_CACHE set after the write 2375 * completes or it will represent a corrupt state. To 2376 * deal with this we set B_NOCACHE to scrap the buffer 2377 * after the write. 2378 * 2379 * We might be able to do something fancy, like setting 2380 * B_CACHE in bwrite() except if B_DELWRI is already set, 2381 * so the below call doesn't set B_CACHE, but that gets real 2382 * confusing. This is much easier. 2383 */ 2384 2385 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 2386 bp->b_flags |= B_NOCACHE; 2387 BUF_WRITE(bp); 2388 goto loop; 2389 } 2390 2391 splx(s); 2392 bp->b_flags &= ~B_DONE; 2393 } else { 2394 /* 2395 * Buffer is not in-core, create new buffer. The buffer 2396 * returned by getnewbuf() is locked. Note that the returned 2397 * buffer is also considered valid (not marked B_INVAL). 2398 */ 2399 int bsize, maxsize, vmio; 2400 off_t offset; 2401 2402 if (vn_isdisk(vp, NULL)) 2403 bsize = DEV_BSIZE; 2404 else if (vp->v_mountedhere) 2405 bsize = vp->v_mountedhere->mnt_stat.f_iosize; 2406 else if (vp->v_mount) 2407 bsize = vp->v_mount->mnt_stat.f_iosize; 2408 else 2409 bsize = size; 2410 2411 offset = blkno * bsize; 2412 vmio = (VOP_GETVOBJECT(vp, NULL) == 0) && 2413 (vp->v_vflag & VV_OBJBUF); 2414 maxsize = vmio ? size + (offset & PAGE_MASK) : size; 2415 maxsize = imax(maxsize, bsize); 2416 2417 if ((bp = getnewbuf(slpflag, slptimeo, size, maxsize)) == NULL) { 2418 if (slpflag || slptimeo) { 2419 splx(s); 2420 return NULL; 2421 } 2422 goto loop; 2423 } 2424 2425 /* 2426 * This code is used to make sure that a buffer is not 2427 * created while the getnewbuf routine is blocked. 2428 * This can be a problem whether the vnode is locked or not. 2429 * If the buffer is created out from under us, we have to 2430 * throw away the one we just created. There is now window 2431 * race because we are safely running at splbio() from the 2432 * point of the duplicate buffer creation through to here, 2433 * and we've locked the buffer. 2434 * 2435 * Note: this must occur before we associate the buffer 2436 * with the vp especially considering limitations in 2437 * the splay tree implementation when dealing with duplicate 2438 * lblkno's. 2439 */ 2440 if (gbincore(vp, blkno)) { 2441 bp->b_flags |= B_INVAL; 2442 brelse(bp); 2443 goto loop; 2444 } 2445 2446 /* 2447 * Insert the buffer into the hash, so that it can 2448 * be found by incore. 2449 */ 2450 bp->b_blkno = bp->b_lblkno = blkno; 2451 bp->b_offset = offset; 2452 2453 bgetvp(vp, bp); 2454#ifdef USE_BUFHASH 2455 LIST_REMOVE(bp, b_hash); 2456 bh = bufhash(vp, blkno); 2457 LIST_INSERT_HEAD(bh, bp, b_hash); 2458#endif 2459 2460 /* 2461 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 2462 * buffer size starts out as 0, B_CACHE will be set by 2463 * allocbuf() for the VMIO case prior to it testing the 2464 * backing store for validity. 2465 */ 2466 2467 if (vmio) { 2468 bp->b_flags |= B_VMIO; 2469#if defined(VFS_BIO_DEBUG) 2470 if (vp->v_type != VREG) 2471 printf("getblk: vmioing file type %d???\n", vp->v_type); 2472#endif 2473 VOP_GETVOBJECT(vp, &bp->b_object); 2474 } else { 2475 bp->b_flags &= ~B_VMIO; 2476 bp->b_object = NULL; 2477 } 2478 2479 allocbuf(bp, size); 2480 2481 splx(s); 2482 bp->b_flags &= ~B_DONE; 2483 } 2484 KASSERT(BUF_REFCNT(bp) == 1, ("getblk: bp %p not locked",bp)); 2485 return (bp); 2486} 2487 2488/* 2489 * Get an empty, disassociated buffer of given size. The buffer is initially 2490 * set to B_INVAL. 2491 */ 2492struct buf * 2493geteblk(int size) 2494{ 2495 struct buf *bp; 2496 int s; 2497 int maxsize; 2498 2499 maxsize = (size + BKVAMASK) & ~BKVAMASK; 2500 2501 s = splbio(); 2502 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0); 2503 splx(s); 2504 allocbuf(bp, size); 2505 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 2506 KASSERT(BUF_REFCNT(bp) == 1, ("geteblk: bp %p not locked",bp)); 2507 return (bp); 2508} 2509 2510 2511/* 2512 * This code constitutes the buffer memory from either anonymous system 2513 * memory (in the case of non-VMIO operations) or from an associated 2514 * VM object (in the case of VMIO operations). This code is able to 2515 * resize a buffer up or down. 2516 * 2517 * Note that this code is tricky, and has many complications to resolve 2518 * deadlock or inconsistant data situations. Tread lightly!!! 2519 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 2520 * the caller. Calling this code willy nilly can result in the loss of data. 2521 * 2522 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 2523 * B_CACHE for the non-VMIO case. 2524 */ 2525 2526int 2527allocbuf(struct buf *bp, int size) 2528{ 2529 int newbsize, mbsize; 2530 int i; 2531 2532 GIANT_REQUIRED; 2533 2534 if (BUF_REFCNT(bp) == 0) 2535 panic("allocbuf: buffer not busy"); 2536 2537 if (bp->b_kvasize < size) 2538 panic("allocbuf: buffer too small"); 2539 2540 if ((bp->b_flags & B_VMIO) == 0) { 2541 caddr_t origbuf; 2542 int origbufsize; 2543 /* 2544 * Just get anonymous memory from the kernel. Don't 2545 * mess with B_CACHE. 2546 */ 2547 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2548 if (bp->b_flags & B_MALLOC) 2549 newbsize = mbsize; 2550 else 2551 newbsize = round_page(size); 2552 2553 if (newbsize < bp->b_bufsize) { 2554 /* 2555 * malloced buffers are not shrunk 2556 */ 2557 if (bp->b_flags & B_MALLOC) { 2558 if (newbsize) { 2559 bp->b_bcount = size; 2560 } else { 2561 free(bp->b_data, M_BIOBUF); 2562 if (bp->b_bufsize) { 2563 bufmallocspace -= bp->b_bufsize; 2564 bufspacewakeup(); 2565 bp->b_bufsize = 0; 2566 } 2567 bp->b_data = bp->b_kvabase; 2568 bp->b_bcount = 0; 2569 bp->b_flags &= ~B_MALLOC; 2570 } 2571 return 1; 2572 } 2573 vm_hold_free_pages( 2574 bp, 2575 (vm_offset_t) bp->b_data + newbsize, 2576 (vm_offset_t) bp->b_data + bp->b_bufsize); 2577 } else if (newbsize > bp->b_bufsize) { 2578 /* 2579 * We only use malloced memory on the first allocation. 2580 * and revert to page-allocated memory when the buffer 2581 * grows. 2582 */ 2583 if ( (bufmallocspace < maxbufmallocspace) && 2584 (bp->b_bufsize == 0) && 2585 (mbsize <= PAGE_SIZE/2)) { 2586 2587 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 2588 bp->b_bufsize = mbsize; 2589 bp->b_bcount = size; 2590 bp->b_flags |= B_MALLOC; 2591 bufmallocspace += mbsize; 2592 return 1; 2593 } 2594 origbuf = NULL; 2595 origbufsize = 0; 2596 /* 2597 * If the buffer is growing on its other-than-first allocation, 2598 * then we revert to the page-allocation scheme. 2599 */ 2600 if (bp->b_flags & B_MALLOC) { 2601 origbuf = bp->b_data; 2602 origbufsize = bp->b_bufsize; 2603 bp->b_data = bp->b_kvabase; 2604 if (bp->b_bufsize) { 2605 bufmallocspace -= bp->b_bufsize; 2606 bufspacewakeup(); 2607 bp->b_bufsize = 0; 2608 } 2609 bp->b_flags &= ~B_MALLOC; 2610 newbsize = round_page(newbsize); 2611 } 2612 vm_hold_load_pages( 2613 bp, 2614 (vm_offset_t) bp->b_data + bp->b_bufsize, 2615 (vm_offset_t) bp->b_data + newbsize); 2616 if (origbuf) { 2617 bcopy(origbuf, bp->b_data, origbufsize); 2618 free(origbuf, M_BIOBUF); 2619 } 2620 } 2621 } else { 2622 vm_page_t m; 2623 int desiredpages; 2624 2625 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2626 desiredpages = (size == 0) ? 0 : 2627 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 2628 2629 if (bp->b_flags & B_MALLOC) 2630 panic("allocbuf: VMIO buffer can't be malloced"); 2631 /* 2632 * Set B_CACHE initially if buffer is 0 length or will become 2633 * 0-length. 2634 */ 2635 if (size == 0 || bp->b_bufsize == 0) 2636 bp->b_flags |= B_CACHE; 2637 2638 if (newbsize < bp->b_bufsize) { 2639 /* 2640 * DEV_BSIZE aligned new buffer size is less then the 2641 * DEV_BSIZE aligned existing buffer size. Figure out 2642 * if we have to remove any pages. 2643 */ 2644 if (desiredpages < bp->b_npages) { 2645 vm_page_lock_queues(); 2646 for (i = desiredpages; i < bp->b_npages; i++) { 2647 /* 2648 * the page is not freed here -- it 2649 * is the responsibility of 2650 * vnode_pager_setsize 2651 */ 2652 m = bp->b_pages[i]; 2653 KASSERT(m != bogus_page, 2654 ("allocbuf: bogus page found")); 2655 while (vm_page_sleep_if_busy(m, TRUE, "biodep")) 2656 vm_page_lock_queues(); 2657 2658 bp->b_pages[i] = NULL; 2659 vm_page_unwire(m, 0); 2660 } 2661 vm_page_unlock_queues(); 2662 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) + 2663 (desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages)); 2664 bp->b_npages = desiredpages; 2665 } 2666 } else if (size > bp->b_bcount) { 2667 /* 2668 * We are growing the buffer, possibly in a 2669 * byte-granular fashion. 2670 */ 2671 struct vnode *vp; 2672 vm_object_t obj; 2673 vm_offset_t toff; 2674 vm_offset_t tinc; 2675 2676 /* 2677 * Step 1, bring in the VM pages from the object, 2678 * allocating them if necessary. We must clear 2679 * B_CACHE if these pages are not valid for the 2680 * range covered by the buffer. 2681 */ 2682 2683 vp = bp->b_vp; 2684 obj = bp->b_object; 2685 2686 while (bp->b_npages < desiredpages) { 2687 vm_page_t m; 2688 vm_pindex_t pi; 2689 2690 pi = OFF_TO_IDX(bp->b_offset) + bp->b_npages; 2691 if ((m = vm_page_lookup(obj, pi)) == NULL) { 2692 /* 2693 * note: must allocate system pages 2694 * since blocking here could intefere 2695 * with paging I/O, no matter which 2696 * process we are. 2697 */ 2698 m = vm_page_alloc(obj, pi, 2699 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED); 2700 if (m == NULL) { 2701 VM_WAIT; 2702 vm_pageout_deficit += desiredpages - bp->b_npages; 2703 } else { 2704 vm_page_lock_queues(); 2705 vm_page_wakeup(m); 2706 vm_page_unlock_queues(); 2707 bp->b_flags &= ~B_CACHE; 2708 bp->b_pages[bp->b_npages] = m; 2709 ++bp->b_npages; 2710 } 2711 continue; 2712 } 2713 2714 /* 2715 * We found a page. If we have to sleep on it, 2716 * retry because it might have gotten freed out 2717 * from under us. 2718 * 2719 * We can only test PG_BUSY here. Blocking on 2720 * m->busy might lead to a deadlock: 2721 * 2722 * vm_fault->getpages->cluster_read->allocbuf 2723 * 2724 */ 2725 vm_page_lock_queues(); 2726 if (vm_page_sleep_if_busy(m, FALSE, "pgtblk")) 2727 continue; 2728 2729 /* 2730 * We have a good page. Should we wakeup the 2731 * page daemon? 2732 */ 2733 if ((curproc != pageproc) && 2734 ((m->queue - m->pc) == PQ_CACHE) && 2735 ((cnt.v_free_count + cnt.v_cache_count) < 2736 (cnt.v_free_min + cnt.v_cache_min))) { 2737 pagedaemon_wakeup(); 2738 } 2739 vm_page_flag_clear(m, PG_ZERO); 2740 vm_page_wire(m); 2741 vm_page_unlock_queues(); 2742 bp->b_pages[bp->b_npages] = m; 2743 ++bp->b_npages; 2744 } 2745 2746 /* 2747 * Step 2. We've loaded the pages into the buffer, 2748 * we have to figure out if we can still have B_CACHE 2749 * set. Note that B_CACHE is set according to the 2750 * byte-granular range ( bcount and size ), new the 2751 * aligned range ( newbsize ). 2752 * 2753 * The VM test is against m->valid, which is DEV_BSIZE 2754 * aligned. Needless to say, the validity of the data 2755 * needs to also be DEV_BSIZE aligned. Note that this 2756 * fails with NFS if the server or some other client 2757 * extends the file's EOF. If our buffer is resized, 2758 * B_CACHE may remain set! XXX 2759 */ 2760 2761 toff = bp->b_bcount; 2762 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 2763 2764 while ((bp->b_flags & B_CACHE) && toff < size) { 2765 vm_pindex_t pi; 2766 2767 if (tinc > (size - toff)) 2768 tinc = size - toff; 2769 2770 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 2771 PAGE_SHIFT; 2772 2773 vfs_buf_test_cache( 2774 bp, 2775 bp->b_offset, 2776 toff, 2777 tinc, 2778 bp->b_pages[pi] 2779 ); 2780 toff += tinc; 2781 tinc = PAGE_SIZE; 2782 } 2783 2784 /* 2785 * Step 3, fixup the KVM pmap. Remember that 2786 * bp->b_data is relative to bp->b_offset, but 2787 * bp->b_offset may be offset into the first page. 2788 */ 2789 2790 bp->b_data = (caddr_t) 2791 trunc_page((vm_offset_t)bp->b_data); 2792 pmap_qenter( 2793 (vm_offset_t)bp->b_data, 2794 bp->b_pages, 2795 bp->b_npages 2796 ); 2797 2798 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 2799 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 2800 } 2801 } 2802 if (newbsize < bp->b_bufsize) 2803 bufspacewakeup(); 2804 bp->b_bufsize = newbsize; /* actual buffer allocation */ 2805 bp->b_bcount = size; /* requested buffer size */ 2806 return 1; 2807} 2808 2809void 2810biodone(struct bio *bp) 2811{ 2812 bp->bio_flags |= BIO_DONE; 2813 if (bp->bio_done != NULL) 2814 bp->bio_done(bp); 2815 else 2816 wakeup(bp); 2817} 2818 2819/* 2820 * Wait for a BIO to finish. 2821 * XXX: For now resort to a timeout, the optimal locking (if any) for this 2822 * case is not at this point obvious. 2823 */ 2824int 2825biowait(struct bio *bp, const char *wchan) 2826{ 2827 2828 while ((bp->bio_flags & BIO_DONE) == 0) 2829 msleep(bp, NULL, 0, wchan, hz); 2830 if (!(bp->bio_flags & BIO_ERROR)) 2831 return (0); 2832 if (bp->bio_error) 2833 return (bp->bio_error); 2834 return (EIO); 2835} 2836 2837/* 2838 * bufwait: 2839 * 2840 * Wait for buffer I/O completion, returning error status. The buffer 2841 * is left locked and B_DONE on return. B_EINTR is converted into a EINTR 2842 * error and cleared. 2843 */ 2844int 2845bufwait(register struct buf * bp) 2846{ 2847 int s; 2848 2849 s = splbio(); 2850 while ((bp->b_flags & B_DONE) == 0) { 2851 if (bp->b_iocmd == BIO_READ) 2852 tsleep(bp, PRIBIO, "biord", 0); 2853 else 2854 tsleep(bp, PRIBIO, "biowr", 0); 2855 } 2856 splx(s); 2857 if (bp->b_flags & B_EINTR) { 2858 bp->b_flags &= ~B_EINTR; 2859 return (EINTR); 2860 } 2861 if (bp->b_ioflags & BIO_ERROR) { 2862 return (bp->b_error ? bp->b_error : EIO); 2863 } else { 2864 return (0); 2865 } 2866} 2867 2868 /* 2869 * Call back function from struct bio back up to struct buf. 2870 * The corresponding initialization lives in sys/conf.h:DEV_STRATEGY(). 2871 */ 2872void 2873bufdonebio(struct bio *bp) 2874{ 2875 bufdone(bp->bio_caller2); 2876} 2877 2878/* 2879 * bufdone: 2880 * 2881 * Finish I/O on a buffer, optionally calling a completion function. 2882 * This is usually called from an interrupt so process blocking is 2883 * not allowed. 2884 * 2885 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 2886 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 2887 * assuming B_INVAL is clear. 2888 * 2889 * For the VMIO case, we set B_CACHE if the op was a read and no 2890 * read error occured, or if the op was a write. B_CACHE is never 2891 * set if the buffer is invalid or otherwise uncacheable. 2892 * 2893 * biodone does not mess with B_INVAL, allowing the I/O routine or the 2894 * initiator to leave B_INVAL set to brelse the buffer out of existance 2895 * in the biodone routine. 2896 */ 2897void 2898bufdone(struct buf *bp) 2899{ 2900 int s; 2901 void (*biodone)(struct buf *); 2902 2903 GIANT_REQUIRED; 2904 2905 s = splbio(); 2906 2907 KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp, BUF_REFCNT(bp))); 2908 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 2909 2910 bp->b_flags |= B_DONE; 2911 runningbufwakeup(bp); 2912 2913 if (bp->b_iocmd == BIO_DELETE) { 2914 brelse(bp); 2915 splx(s); 2916 return; 2917 } 2918 2919 if (bp->b_iocmd == BIO_WRITE) { 2920 vwakeup(bp); 2921 } 2922 2923 /* call optional completion function if requested */ 2924 if (bp->b_iodone != NULL) { 2925 biodone = bp->b_iodone; 2926 bp->b_iodone = NULL; 2927 (*biodone) (bp); 2928 splx(s); 2929 return; 2930 } 2931 if (LIST_FIRST(&bp->b_dep) != NULL) 2932 buf_complete(bp); 2933 2934 if (bp->b_flags & B_VMIO) { 2935 int i; 2936 vm_ooffset_t foff; 2937 vm_page_t m; 2938 vm_object_t obj; 2939 int iosize; 2940 struct vnode *vp = bp->b_vp; 2941 2942 obj = bp->b_object; 2943 2944#if defined(VFS_BIO_DEBUG) 2945 mp_fixme("usecount and vflag accessed without locks."); 2946 if (vp->v_usecount == 0) { 2947 panic("biodone: zero vnode ref count"); 2948 } 2949 2950 if ((vp->v_vflag & VV_OBJBUF) == 0) { 2951 panic("biodone: vnode is not setup for merged cache"); 2952 } 2953#endif 2954 2955 foff = bp->b_offset; 2956 KASSERT(bp->b_offset != NOOFFSET, 2957 ("biodone: no buffer offset")); 2958 2959#if defined(VFS_BIO_DEBUG) 2960 if (obj->paging_in_progress < bp->b_npages) { 2961 printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n", 2962 obj->paging_in_progress, bp->b_npages); 2963 } 2964#endif 2965 2966 /* 2967 * Set B_CACHE if the op was a normal read and no error 2968 * occured. B_CACHE is set for writes in the b*write() 2969 * routines. 2970 */ 2971 iosize = bp->b_bcount - bp->b_resid; 2972 if (bp->b_iocmd == BIO_READ && 2973 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 2974 !(bp->b_ioflags & BIO_ERROR)) { 2975 bp->b_flags |= B_CACHE; 2976 } 2977 vm_page_lock_queues(); 2978 for (i = 0; i < bp->b_npages; i++) { 2979 int bogusflag = 0; 2980 int resid; 2981 2982 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 2983 if (resid > iosize) 2984 resid = iosize; 2985 2986 /* 2987 * cleanup bogus pages, restoring the originals 2988 */ 2989 m = bp->b_pages[i]; 2990 if (m == bogus_page) { 2991 bogusflag = 1; 2992 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 2993 if (m == NULL) 2994 panic("biodone: page disappeared!"); 2995 bp->b_pages[i] = m; 2996 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 2997 } 2998#if defined(VFS_BIO_DEBUG) 2999 if (OFF_TO_IDX(foff) != m->pindex) { 3000 printf( 3001"biodone: foff(%jd)/m->pindex(%ju) mismatch\n", 3002 (intmax_t)foff, (uintmax_t)m->pindex); 3003 } 3004#endif 3005 3006 /* 3007 * In the write case, the valid and clean bits are 3008 * already changed correctly ( see bdwrite() ), so we 3009 * only need to do this here in the read case. 3010 */ 3011 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 3012 vfs_page_set_valid(bp, foff, i, m); 3013 } 3014 vm_page_flag_clear(m, PG_ZERO); 3015 3016 /* 3017 * when debugging new filesystems or buffer I/O methods, this 3018 * is the most common error that pops up. if you see this, you 3019 * have not set the page busy flag correctly!!! 3020 */ 3021 if (m->busy == 0) { 3022 printf("biodone: page busy < 0, " 3023 "pindex: %d, foff: 0x(%x,%x), " 3024 "resid: %d, index: %d\n", 3025 (int) m->pindex, (int)(foff >> 32), 3026 (int) foff & 0xffffffff, resid, i); 3027 if (!vn_isdisk(vp, NULL)) 3028 printf(" iosize: %ld, lblkno: %jd, flags: 0x%lx, npages: %d\n", 3029 bp->b_vp->v_mount->mnt_stat.f_iosize, 3030 (intmax_t) bp->b_lblkno, 3031 bp->b_flags, bp->b_npages); 3032 else 3033 printf(" VDEV, lblkno: %jd, flags: 0x%lx, npages: %d\n", 3034 (intmax_t) bp->b_lblkno, 3035 bp->b_flags, bp->b_npages); 3036 printf(" valid: 0x%x, dirty: 0x%x, wired: %d\n", 3037 m->valid, m->dirty, m->wire_count); 3038 panic("biodone: page busy < 0\n"); 3039 } 3040 vm_page_io_finish(m); 3041 vm_object_pip_subtract(obj, 1); 3042 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3043 iosize -= resid; 3044 } 3045 vm_page_unlock_queues(); 3046 if (obj) 3047 vm_object_pip_wakeupn(obj, 0); 3048 } 3049 3050 /* 3051 * For asynchronous completions, release the buffer now. The brelse 3052 * will do a wakeup there if necessary - so no need to do a wakeup 3053 * here in the async case. The sync case always needs to do a wakeup. 3054 */ 3055 3056 if (bp->b_flags & B_ASYNC) { 3057 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 3058 brelse(bp); 3059 else 3060 bqrelse(bp); 3061 } else { 3062 wakeup(bp); 3063 } 3064 splx(s); 3065} 3066 3067/* 3068 * This routine is called in lieu of iodone in the case of 3069 * incomplete I/O. This keeps the busy status for pages 3070 * consistant. 3071 */ 3072void 3073vfs_unbusy_pages(struct buf * bp) 3074{ 3075 int i; 3076 3077 GIANT_REQUIRED; 3078 3079 runningbufwakeup(bp); 3080 if (bp->b_flags & B_VMIO) { 3081 vm_object_t obj; 3082 3083 obj = bp->b_object; 3084 vm_page_lock_queues(); 3085 for (i = 0; i < bp->b_npages; i++) { 3086 vm_page_t m = bp->b_pages[i]; 3087 3088 if (m == bogus_page) { 3089 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 3090 if (!m) { 3091 panic("vfs_unbusy_pages: page missing\n"); 3092 } 3093 bp->b_pages[i] = m; 3094 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 3095 } 3096 vm_object_pip_subtract(obj, 1); 3097 vm_page_flag_clear(m, PG_ZERO); 3098 vm_page_io_finish(m); 3099 } 3100 vm_page_unlock_queues(); 3101 vm_object_pip_wakeupn(obj, 0); 3102 } 3103} 3104 3105/* 3106 * vfs_page_set_valid: 3107 * 3108 * Set the valid bits in a page based on the supplied offset. The 3109 * range is restricted to the buffer's size. 3110 * 3111 * This routine is typically called after a read completes. 3112 */ 3113static void 3114vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m) 3115{ 3116 vm_ooffset_t soff, eoff; 3117 3118 GIANT_REQUIRED; 3119 /* 3120 * Start and end offsets in buffer. eoff - soff may not cross a 3121 * page boundry or cross the end of the buffer. The end of the 3122 * buffer, in this case, is our file EOF, not the allocation size 3123 * of the buffer. 3124 */ 3125 soff = off; 3126 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3127 if (eoff > bp->b_offset + bp->b_bcount) 3128 eoff = bp->b_offset + bp->b_bcount; 3129 3130 /* 3131 * Set valid range. This is typically the entire buffer and thus the 3132 * entire page. 3133 */ 3134 if (eoff > soff) { 3135 vm_page_set_validclean( 3136 m, 3137 (vm_offset_t) (soff & PAGE_MASK), 3138 (vm_offset_t) (eoff - soff) 3139 ); 3140 } 3141} 3142 3143/* 3144 * This routine is called before a device strategy routine. 3145 * It is used to tell the VM system that paging I/O is in 3146 * progress, and treat the pages associated with the buffer 3147 * almost as being PG_BUSY. Also the object paging_in_progress 3148 * flag is handled to make sure that the object doesn't become 3149 * inconsistant. 3150 * 3151 * Since I/O has not been initiated yet, certain buffer flags 3152 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 3153 * and should be ignored. 3154 */ 3155void 3156vfs_busy_pages(struct buf * bp, int clear_modify) 3157{ 3158 int i, bogus; 3159 3160 if (bp->b_flags & B_VMIO) { 3161 vm_object_t obj; 3162 vm_ooffset_t foff; 3163 3164 obj = bp->b_object; 3165 foff = bp->b_offset; 3166 KASSERT(bp->b_offset != NOOFFSET, 3167 ("vfs_busy_pages: no buffer offset")); 3168 vfs_setdirty(bp); 3169retry: 3170 vm_page_lock_queues(); 3171 for (i = 0; i < bp->b_npages; i++) { 3172 vm_page_t m = bp->b_pages[i]; 3173 3174 if (vm_page_sleep_if_busy(m, FALSE, "vbpage")) 3175 goto retry; 3176 } 3177 bogus = 0; 3178 for (i = 0; i < bp->b_npages; i++) { 3179 vm_page_t m = bp->b_pages[i]; 3180 3181 vm_page_flag_clear(m, PG_ZERO); 3182 if ((bp->b_flags & B_CLUSTER) == 0) { 3183 vm_object_pip_add(obj, 1); 3184 vm_page_io_start(m); 3185 } 3186 /* 3187 * When readying a buffer for a read ( i.e 3188 * clear_modify == 0 ), it is important to do 3189 * bogus_page replacement for valid pages in 3190 * partially instantiated buffers. Partially 3191 * instantiated buffers can, in turn, occur when 3192 * reconstituting a buffer from its VM backing store 3193 * base. We only have to do this if B_CACHE is 3194 * clear ( which causes the I/O to occur in the 3195 * first place ). The replacement prevents the read 3196 * I/O from overwriting potentially dirty VM-backed 3197 * pages. XXX bogus page replacement is, uh, bogus. 3198 * It may not work properly with small-block devices. 3199 * We need to find a better way. 3200 */ 3201 vm_page_protect(m, VM_PROT_NONE); 3202 if (clear_modify) 3203 vfs_page_set_valid(bp, foff, i, m); 3204 else if (m->valid == VM_PAGE_BITS_ALL && 3205 (bp->b_flags & B_CACHE) == 0) { 3206 bp->b_pages[i] = bogus_page; 3207 bogus++; 3208 } 3209 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3210 } 3211 vm_page_unlock_queues(); 3212 if (bogus) 3213 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 3214 } 3215} 3216 3217/* 3218 * Tell the VM system that the pages associated with this buffer 3219 * are clean. This is used for delayed writes where the data is 3220 * going to go to disk eventually without additional VM intevention. 3221 * 3222 * Note that while we only really need to clean through to b_bcount, we 3223 * just go ahead and clean through to b_bufsize. 3224 */ 3225static void 3226vfs_clean_pages(struct buf * bp) 3227{ 3228 int i; 3229 3230 GIANT_REQUIRED; 3231 3232 if (bp->b_flags & B_VMIO) { 3233 vm_ooffset_t foff; 3234 3235 foff = bp->b_offset; 3236 KASSERT(bp->b_offset != NOOFFSET, 3237 ("vfs_clean_pages: no buffer offset")); 3238 for (i = 0; i < bp->b_npages; i++) { 3239 vm_page_t m = bp->b_pages[i]; 3240 vm_ooffset_t noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3241 vm_ooffset_t eoff = noff; 3242 3243 if (eoff > bp->b_offset + bp->b_bufsize) 3244 eoff = bp->b_offset + bp->b_bufsize; 3245 vfs_page_set_valid(bp, foff, i, m); 3246 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3247 foff = noff; 3248 } 3249 } 3250} 3251 3252/* 3253 * vfs_bio_set_validclean: 3254 * 3255 * Set the range within the buffer to valid and clean. The range is 3256 * relative to the beginning of the buffer, b_offset. Note that b_offset 3257 * itself may be offset from the beginning of the first page. 3258 * 3259 */ 3260 3261void 3262vfs_bio_set_validclean(struct buf *bp, int base, int size) 3263{ 3264 if (bp->b_flags & B_VMIO) { 3265 int i; 3266 int n; 3267 3268 /* 3269 * Fixup base to be relative to beginning of first page. 3270 * Set initial n to be the maximum number of bytes in the 3271 * first page that can be validated. 3272 */ 3273 3274 base += (bp->b_offset & PAGE_MASK); 3275 n = PAGE_SIZE - (base & PAGE_MASK); 3276 3277 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 3278 vm_page_t m = bp->b_pages[i]; 3279 3280 if (n > size) 3281 n = size; 3282 3283 vm_page_set_validclean(m, base & PAGE_MASK, n); 3284 base += n; 3285 size -= n; 3286 n = PAGE_SIZE; 3287 } 3288 } 3289} 3290 3291/* 3292 * vfs_bio_clrbuf: 3293 * 3294 * clear a buffer. This routine essentially fakes an I/O, so we need 3295 * to clear BIO_ERROR and B_INVAL. 3296 * 3297 * Note that while we only theoretically need to clear through b_bcount, 3298 * we go ahead and clear through b_bufsize. 3299 */ 3300 3301void 3302vfs_bio_clrbuf(struct buf *bp) 3303{ 3304 int i, mask = 0; 3305 caddr_t sa, ea; 3306 3307 GIANT_REQUIRED; 3308 3309 if ((bp->b_flags & (B_VMIO | B_MALLOC)) == B_VMIO) { 3310 bp->b_flags &= ~B_INVAL; 3311 bp->b_ioflags &= ~BIO_ERROR; 3312 if( (bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 3313 (bp->b_offset & PAGE_MASK) == 0) { 3314 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 3315 if ((bp->b_pages[0]->valid & mask) == mask) { 3316 bp->b_resid = 0; 3317 return; 3318 } 3319 if (((bp->b_pages[0]->flags & PG_ZERO) == 0) && 3320 ((bp->b_pages[0]->valid & mask) == 0)) { 3321 bzero(bp->b_data, bp->b_bufsize); 3322 bp->b_pages[0]->valid |= mask; 3323 bp->b_resid = 0; 3324 return; 3325 } 3326 } 3327 ea = sa = bp->b_data; 3328 for(i=0;i<bp->b_npages;i++,sa=ea) { 3329 int j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; 3330 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); 3331 ea = (caddr_t)(vm_offset_t)ulmin( 3332 (u_long)(vm_offset_t)ea, 3333 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); 3334 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 3335 if ((bp->b_pages[i]->valid & mask) == mask) 3336 continue; 3337 if ((bp->b_pages[i]->valid & mask) == 0) { 3338 if ((bp->b_pages[i]->flags & PG_ZERO) == 0) { 3339 bzero(sa, ea - sa); 3340 } 3341 } else { 3342 for (; sa < ea; sa += DEV_BSIZE, j++) { 3343 if (((bp->b_pages[i]->flags & PG_ZERO) == 0) && 3344 (bp->b_pages[i]->valid & (1<<j)) == 0) 3345 bzero(sa, DEV_BSIZE); 3346 } 3347 } 3348 bp->b_pages[i]->valid |= mask; 3349 vm_page_flag_clear(bp->b_pages[i], PG_ZERO); 3350 } 3351 bp->b_resid = 0; 3352 } else { 3353 clrbuf(bp); 3354 } 3355} 3356 3357/* 3358 * vm_hold_load_pages and vm_hold_free_pages get pages into 3359 * a buffers address space. The pages are anonymous and are 3360 * not associated with a file object. 3361 */ 3362static void 3363vm_hold_load_pages(struct buf * bp, vm_offset_t from, vm_offset_t to) 3364{ 3365 vm_offset_t pg; 3366 vm_page_t p; 3367 int index; 3368 3369 GIANT_REQUIRED; 3370 3371 to = round_page(to); 3372 from = round_page(from); 3373 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3374 3375 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3376tryagain: 3377 /* 3378 * note: must allocate system pages since blocking here 3379 * could intefere with paging I/O, no matter which 3380 * process we are. 3381 */ 3382 p = vm_page_alloc(kernel_object, 3383 ((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 3384 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED); 3385 if (!p) { 3386 vm_pageout_deficit += (to - from) >> PAGE_SHIFT; 3387 VM_WAIT; 3388 goto tryagain; 3389 } 3390 vm_page_lock_queues(); 3391 p->valid = VM_PAGE_BITS_ALL; 3392 vm_page_flag_clear(p, PG_ZERO); 3393 vm_page_unlock_queues(); 3394 pmap_qenter(pg, &p, 1); 3395 bp->b_pages[index] = p; 3396 vm_page_wakeup(p); 3397 } 3398 bp->b_npages = index; 3399} 3400 3401/* Return pages associated with this buf to the vm system */ 3402void 3403vm_hold_free_pages(struct buf * bp, vm_offset_t from, vm_offset_t to) 3404{ 3405 vm_offset_t pg; 3406 vm_page_t p; 3407 int index, newnpages; 3408 3409 GIANT_REQUIRED; 3410 3411 from = round_page(from); 3412 to = round_page(to); 3413 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3414 3415 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3416 p = bp->b_pages[index]; 3417 if (p && (index < bp->b_npages)) { 3418 if (p->busy) { 3419 printf( 3420 "vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 3421 (intmax_t)bp->b_blkno, 3422 (intmax_t)bp->b_lblkno); 3423 } 3424 bp->b_pages[index] = NULL; 3425 pmap_qremove(pg, 1); 3426 vm_page_lock_queues(); 3427 vm_page_busy(p); 3428 vm_page_unwire(p, 0); 3429 vm_page_free(p); 3430 vm_page_unlock_queues(); 3431 } 3432 } 3433 bp->b_npages = newnpages; 3434} 3435 3436 3437#include "opt_ddb.h" 3438#ifdef DDB 3439#include <ddb/ddb.h> 3440 3441/* DDB command to show buffer data */ 3442DB_SHOW_COMMAND(buffer, db_show_buffer) 3443{ 3444 /* get args */ 3445 struct buf *bp = (struct buf *)addr; 3446 3447 if (!have_addr) { 3448 db_printf("usage: show buffer <addr>\n"); 3449 return; 3450 } 3451 3452 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS); 3453 db_printf( 3454 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 3455 "b_dev = (%d,%d), b_data = %p, b_blkno = %jd, b_pblkno = %jd\n", 3456 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 3457 major(bp->b_dev), minor(bp->b_dev), bp->b_data, 3458 (intmax_t)bp->b_blkno, (intmax_t)bp->b_pblkno); 3459 if (bp->b_npages) { 3460 int i; 3461 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 3462 for (i = 0; i < bp->b_npages; i++) { 3463 vm_page_t m; 3464 m = bp->b_pages[i]; 3465 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 3466 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 3467 if ((i + 1) < bp->b_npages) 3468 db_printf(","); 3469 } 3470 db_printf("\n"); 3471 } 3472} 3473#endif /* DDB */ 3474