vfs_bio.c revision 135135
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 15/* 16 * this file contains a new buffer I/O scheme implementing a coherent 17 * VM object and buffer cache scheme. Pains have been taken to make 18 * sure that the performance degradation associated with schemes such 19 * as this is not realized. 20 * 21 * Author: John S. Dyson 22 * Significant help during the development and debugging phases 23 * had been provided by David Greenman, also of the FreeBSD core team. 24 * 25 * see man buf(9) for more info. 26 */ 27 28#include <sys/cdefs.h> 29__FBSDID("$FreeBSD: head/sys/kern/vfs_bio.c 135135 2004-09-13 06:50:42Z phk $"); 30 31#include <sys/param.h> 32#include <sys/systm.h> 33#include <sys/bio.h> 34#include <sys/conf.h> 35#include <sys/buf.h> 36#include <sys/devicestat.h> 37#include <sys/eventhandler.h> 38#include <sys/lock.h> 39#include <sys/malloc.h> 40#include <sys/mount.h> 41#include <sys/mutex.h> 42#include <sys/kernel.h> 43#include <sys/kthread.h> 44#include <sys/proc.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#include "opt_directio.h" 58#include "opt_swap.h" 59 60static MALLOC_DEFINE(M_BIOBUF, "BIO buffer", "BIO buffer"); 61 62struct bio_ops bioops; /* I/O operation notification */ 63 64static int ibwrite(struct buf *); 65 66struct buf_ops buf_ops_bio = { 67 "buf_ops_bio", 68 ibwrite 69}; 70 71/* 72 * XXX buf is global because kern_shutdown.c and ffs_checkoverlap has 73 * carnal knowledge of buffers. This knowledge should be moved to vfs_bio.c. 74 */ 75struct buf *buf; /* buffer header pool */ 76 77static struct proc *bufdaemonproc; 78 79static void vm_hold_free_pages(struct buf * bp, vm_offset_t from, 80 vm_offset_t to); 81static void vm_hold_load_pages(struct buf * bp, vm_offset_t from, 82 vm_offset_t to); 83static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, 84 int pageno, vm_page_t m); 85static void vfs_clean_pages(struct buf * bp); 86static void vfs_setdirty(struct buf *bp); 87static void vfs_vmio_release(struct buf *bp); 88static void vfs_backgroundwritedone(struct buf *bp); 89static int vfs_bio_clcheck(struct vnode *vp, int size, 90 daddr_t lblkno, daddr_t blkno); 91static int flushbufqueues(int flushdeps); 92static void buf_daemon(void); 93void bremfreel(struct buf * bp); 94 95int vmiodirenable = TRUE; 96SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, 97 "Use the VM system for directory writes"); 98int runningbufspace; 99SYSCTL_INT(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 100 "Amount of presently outstanding async buffer io"); 101static int bufspace; 102SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, 103 "KVA memory used for bufs"); 104static int maxbufspace; 105SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0, 106 "Maximum allowed value of bufspace (including buf_daemon)"); 107static int bufmallocspace; 108SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 109 "Amount of malloced memory for buffers"); 110static int maxbufmallocspace; 111SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0, 112 "Maximum amount of malloced memory for buffers"); 113static int lobufspace; 114SYSCTL_INT(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0, 115 "Minimum amount of buffers we want to have"); 116static int hibufspace; 117SYSCTL_INT(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0, 118 "Maximum allowed value of bufspace (excluding buf_daemon)"); 119static int bufreusecnt; 120SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0, 121 "Number of times we have reused a buffer"); 122static int buffreekvacnt; 123SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0, 124 "Number of times we have freed the KVA space from some buffer"); 125static int bufdefragcnt; 126SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0, 127 "Number of times we have had to repeat buffer allocation to defragment"); 128static int lorunningspace; 129SYSCTL_INT(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0, 130 "Minimum preferred space used for in-progress I/O"); 131static int hirunningspace; 132SYSCTL_INT(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0, 133 "Maximum amount of space to use for in-progress I/O"); 134static int dirtybufferflushes; 135SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes, 136 0, "Number of bdwrite to bawrite conversions to limit dirty buffers"); 137static int altbufferflushes; 138SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes, 139 0, "Number of fsync flushes to limit dirty buffers"); 140static int recursiveflushes; 141SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes, 142 0, "Number of flushes skipped due to being recursive"); 143static int numdirtybuffers; 144SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0, 145 "Number of buffers that are dirty (has unwritten changes) at the moment"); 146static int lodirtybuffers; 147SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0, 148 "How many buffers we want to have free before bufdaemon can sleep"); 149static int hidirtybuffers; 150SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0, 151 "When the number of dirty buffers is considered severe"); 152static int dirtybufthresh; 153SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh, 154 0, "Number of bdwrite to bawrite conversions to clear dirty buffers"); 155static int numfreebuffers; 156SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, 157 "Number of free buffers"); 158static int lofreebuffers; 159SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0, 160 "XXX Unused"); 161static int hifreebuffers; 162SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0, 163 "XXX Complicatedly unused"); 164static int getnewbufcalls; 165SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0, 166 "Number of calls to getnewbuf"); 167static int getnewbufrestarts; 168SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0, 169 "Number of times getnewbuf has had to restart a buffer aquisition"); 170static int dobkgrdwrite = 1; 171SYSCTL_INT(_debug, OID_AUTO, dobkgrdwrite, CTLFLAG_RW, &dobkgrdwrite, 0, 172 "Do background writes (honoring the BV_BKGRDWRITE flag)?"); 173 174/* 175 * Wakeup point for bufdaemon, as well as indicator of whether it is already 176 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it 177 * is idling. 178 */ 179static int bd_request; 180 181/* 182 * This lock synchronizes access to bd_request. 183 */ 184static struct mtx bdlock; 185 186/* 187 * bogus page -- for I/O to/from partially complete buffers 188 * this is a temporary solution to the problem, but it is not 189 * really that bad. it would be better to split the buffer 190 * for input in the case of buffers partially already in memory, 191 * but the code is intricate enough already. 192 */ 193vm_page_t bogus_page; 194 195/* 196 * Synchronization (sleep/wakeup) variable for active buffer space requests. 197 * Set when wait starts, cleared prior to wakeup(). 198 * Used in runningbufwakeup() and waitrunningbufspace(). 199 */ 200static int runningbufreq; 201 202/* 203 * This lock protects the runningbufreq and synchronizes runningbufwakeup and 204 * waitrunningbufspace(). 205 */ 206static struct mtx rbreqlock; 207 208/* 209 * Synchronization (sleep/wakeup) variable for buffer requests. 210 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done 211 * by and/or. 212 * Used in numdirtywakeup(), bufspacewakeup(), bufcountwakeup(), bwillwrite(), 213 * getnewbuf(), and getblk(). 214 */ 215static int needsbuffer; 216 217/* 218 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it. 219 */ 220static struct mtx nblock; 221 222/* 223 * Lock that protects against bwait()/bdone()/B_DONE races. 224 */ 225 226static struct mtx bdonelock; 227 228/* 229 * Definitions for the buffer free lists. 230 */ 231#define BUFFER_QUEUES 5 /* number of free buffer queues */ 232 233#define QUEUE_NONE 0 /* on no queue */ 234#define QUEUE_CLEAN 1 /* non-B_DELWRI buffers */ 235#define QUEUE_DIRTY 2 /* B_DELWRI buffers */ 236#define QUEUE_EMPTYKVA 3 /* empty buffer headers w/KVA assignment */ 237#define QUEUE_EMPTY 4 /* empty buffer headers */ 238 239/* Queues for free buffers with various properties */ 240static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } }; 241 242/* Lock for the bufqueues */ 243static struct mtx bqlock; 244 245/* 246 * Single global constant for BUF_WMESG, to avoid getting multiple references. 247 * buf_wmesg is referred from macros. 248 */ 249const char *buf_wmesg = BUF_WMESG; 250 251#define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 252#define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */ 253#define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ 254#define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 255 256#ifdef DIRECTIO 257extern void ffs_rawread_setup(void); 258#endif /* DIRECTIO */ 259/* 260 * numdirtywakeup: 261 * 262 * If someone is blocked due to there being too many dirty buffers, 263 * and numdirtybuffers is now reasonable, wake them up. 264 */ 265 266static __inline void 267numdirtywakeup(int level) 268{ 269 if (numdirtybuffers <= level) { 270 mtx_lock(&nblock); 271 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) { 272 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH; 273 wakeup(&needsbuffer); 274 } 275 mtx_unlock(&nblock); 276 } 277} 278 279/* 280 * bufspacewakeup: 281 * 282 * Called when buffer space is potentially available for recovery. 283 * getnewbuf() will block on this flag when it is unable to free 284 * sufficient buffer space. Buffer space becomes recoverable when 285 * bp's get placed back in the queues. 286 */ 287 288static __inline void 289bufspacewakeup(void) 290{ 291 /* 292 * If someone is waiting for BUF space, wake them up. Even 293 * though we haven't freed the kva space yet, the waiting 294 * process will be able to now. 295 */ 296 mtx_lock(&nblock); 297 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) { 298 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE; 299 wakeup(&needsbuffer); 300 } 301 mtx_unlock(&nblock); 302} 303 304/* 305 * runningbufwakeup() - in-progress I/O accounting. 306 * 307 */ 308static __inline void 309runningbufwakeup(struct buf *bp) 310{ 311 if (bp->b_runningbufspace) { 312 atomic_subtract_int(&runningbufspace, bp->b_runningbufspace); 313 bp->b_runningbufspace = 0; 314 mtx_lock(&rbreqlock); 315 if (runningbufreq && runningbufspace <= lorunningspace) { 316 runningbufreq = 0; 317 wakeup(&runningbufreq); 318 } 319 mtx_unlock(&rbreqlock); 320 } 321} 322 323/* 324 * bufcountwakeup: 325 * 326 * Called when a buffer has been added to one of the free queues to 327 * account for the buffer and to wakeup anyone waiting for free buffers. 328 * This typically occurs when large amounts of metadata are being handled 329 * by the buffer cache ( else buffer space runs out first, usually ). 330 */ 331 332static __inline void 333bufcountwakeup(void) 334{ 335 atomic_add_int(&numfreebuffers, 1); 336 mtx_lock(&nblock); 337 if (needsbuffer) { 338 needsbuffer &= ~VFS_BIO_NEED_ANY; 339 if (numfreebuffers >= hifreebuffers) 340 needsbuffer &= ~VFS_BIO_NEED_FREE; 341 wakeup(&needsbuffer); 342 } 343 mtx_unlock(&nblock); 344} 345 346/* 347 * waitrunningbufspace() 348 * 349 * runningbufspace is a measure of the amount of I/O currently 350 * running. This routine is used in async-write situations to 351 * prevent creating huge backups of pending writes to a device. 352 * Only asynchronous writes are governed by this function. 353 * 354 * Reads will adjust runningbufspace, but will not block based on it. 355 * The read load has a side effect of reducing the allowed write load. 356 * 357 * This does NOT turn an async write into a sync write. It waits 358 * for earlier writes to complete and generally returns before the 359 * caller's write has reached the device. 360 */ 361static __inline void 362waitrunningbufspace(void) 363{ 364 mtx_lock(&rbreqlock); 365 while (runningbufspace > hirunningspace) { 366 ++runningbufreq; 367 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 368 } 369 mtx_unlock(&rbreqlock); 370} 371 372 373/* 374 * vfs_buf_test_cache: 375 * 376 * Called when a buffer is extended. This function clears the B_CACHE 377 * bit if the newly extended portion of the buffer does not contain 378 * valid data. 379 */ 380static __inline 381void 382vfs_buf_test_cache(struct buf *bp, 383 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 384 vm_page_t m) 385{ 386 GIANT_REQUIRED; 387 388 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 389 if (bp->b_flags & B_CACHE) { 390 int base = (foff + off) & PAGE_MASK; 391 if (vm_page_is_valid(m, base, size) == 0) 392 bp->b_flags &= ~B_CACHE; 393 } 394} 395 396/* Wake up the buffer deamon if necessary */ 397static __inline 398void 399bd_wakeup(int dirtybuflevel) 400{ 401 mtx_lock(&bdlock); 402 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) { 403 bd_request = 1; 404 wakeup(&bd_request); 405 } 406 mtx_unlock(&bdlock); 407} 408 409/* 410 * bd_speedup - speedup the buffer cache flushing code 411 */ 412 413static __inline 414void 415bd_speedup(void) 416{ 417 bd_wakeup(1); 418} 419 420/* 421 * Calculating buffer cache scaling values and reserve space for buffer 422 * headers. This is called during low level kernel initialization and 423 * may be called more then once. We CANNOT write to the memory area 424 * being reserved at this time. 425 */ 426caddr_t 427kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 428{ 429 /* 430 * physmem_est is in pages. Convert it to kilobytes (assumes 431 * PAGE_SIZE is >= 1K) 432 */ 433 physmem_est = physmem_est * (PAGE_SIZE / 1024); 434 435 /* 436 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 437 * For the first 64MB of ram nominally allocate sufficient buffers to 438 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 439 * buffers to cover 1/20 of our ram over 64MB. When auto-sizing 440 * the buffer cache we limit the eventual kva reservation to 441 * maxbcache bytes. 442 * 443 * factor represents the 1/4 x ram conversion. 444 */ 445 if (nbuf == 0) { 446 int factor = 4 * BKVASIZE / 1024; 447 448 nbuf = 50; 449 if (physmem_est > 4096) 450 nbuf += min((physmem_est - 4096) / factor, 451 65536 / factor); 452 if (physmem_est > 65536) 453 nbuf += (physmem_est - 65536) * 2 / (factor * 5); 454 455 if (maxbcache && nbuf > maxbcache / BKVASIZE) 456 nbuf = maxbcache / BKVASIZE; 457 } 458 459#if 0 460 /* 461 * Do not allow the buffer_map to be more then 1/2 the size of the 462 * kernel_map. 463 */ 464 if (nbuf > (kernel_map->max_offset - kernel_map->min_offset) / 465 (BKVASIZE * 2)) { 466 nbuf = (kernel_map->max_offset - kernel_map->min_offset) / 467 (BKVASIZE * 2); 468 printf("Warning: nbufs capped at %d\n", nbuf); 469 } 470#endif 471 472 /* 473 * swbufs are used as temporary holders for I/O, such as paging I/O. 474 * We have no less then 16 and no more then 256. 475 */ 476 nswbuf = max(min(nbuf/4, 256), 16); 477#ifdef NSWBUF_MIN 478 if (nswbuf < NSWBUF_MIN) 479 nswbuf = NSWBUF_MIN; 480#endif 481#ifdef DIRECTIO 482 ffs_rawread_setup(); 483#endif 484 485 /* 486 * Reserve space for the buffer cache buffers 487 */ 488 swbuf = (void *)v; 489 v = (caddr_t)(swbuf + nswbuf); 490 buf = (void *)v; 491 v = (caddr_t)(buf + nbuf); 492 493 return(v); 494} 495 496/* Initialize the buffer subsystem. Called before use of any buffers. */ 497void 498bufinit(void) 499{ 500 struct buf *bp; 501 int i; 502 503 GIANT_REQUIRED; 504 505 mtx_init(&bqlock, "buf queue lock", NULL, MTX_DEF); 506 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 507 mtx_init(&nblock, "needsbuffer lock", NULL, MTX_DEF); 508 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 509 mtx_init(&bdonelock, "bdone lock", NULL, MTX_DEF); 510 511 /* next, make a null set of free lists */ 512 for (i = 0; i < BUFFER_QUEUES; i++) 513 TAILQ_INIT(&bufqueues[i]); 514 515 /* finally, initialize each buffer header and stick on empty q */ 516 for (i = 0; i < nbuf; i++) { 517 bp = &buf[i]; 518 bzero(bp, sizeof *bp); 519 bp->b_flags = B_INVAL; /* we're just an empty header */ 520 bp->b_dev = NULL; 521 bp->b_rcred = NOCRED; 522 bp->b_wcred = NOCRED; 523 bp->b_qindex = QUEUE_EMPTY; 524 bp->b_vflags = 0; 525 bp->b_xflags = 0; 526 LIST_INIT(&bp->b_dep); 527 BUF_LOCKINIT(bp); 528 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 529 } 530 531 /* 532 * maxbufspace is the absolute maximum amount of buffer space we are 533 * allowed to reserve in KVM and in real terms. The absolute maximum 534 * is nominally used by buf_daemon. hibufspace is the nominal maximum 535 * used by most other processes. The differential is required to 536 * ensure that buf_daemon is able to run when other processes might 537 * be blocked waiting for buffer space. 538 * 539 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 540 * this may result in KVM fragmentation which is not handled optimally 541 * by the system. 542 */ 543 maxbufspace = nbuf * BKVASIZE; 544 hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 545 lobufspace = hibufspace - MAXBSIZE; 546 547 lorunningspace = 512 * 1024; 548 hirunningspace = 1024 * 1024; 549 550/* 551 * Limit the amount of malloc memory since it is wired permanently into 552 * the kernel space. Even though this is accounted for in the buffer 553 * allocation, we don't want the malloced region to grow uncontrolled. 554 * The malloc scheme improves memory utilization significantly on average 555 * (small) directories. 556 */ 557 maxbufmallocspace = hibufspace / 20; 558 559/* 560 * Reduce the chance of a deadlock occuring by limiting the number 561 * of delayed-write dirty buffers we allow to stack up. 562 */ 563 hidirtybuffers = nbuf / 4 + 20; 564 dirtybufthresh = hidirtybuffers * 9 / 10; 565 numdirtybuffers = 0; 566/* 567 * To support extreme low-memory systems, make sure hidirtybuffers cannot 568 * eat up all available buffer space. This occurs when our minimum cannot 569 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 570 * BKVASIZE'd (8K) buffers. 571 */ 572 while (hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 573 hidirtybuffers >>= 1; 574 } 575 lodirtybuffers = hidirtybuffers / 2; 576 577/* 578 * Try to keep the number of free buffers in the specified range, 579 * and give special processes (e.g. like buf_daemon) access to an 580 * emergency reserve. 581 */ 582 lofreebuffers = nbuf / 18 + 5; 583 hifreebuffers = 2 * lofreebuffers; 584 numfreebuffers = nbuf; 585 586/* 587 * Maximum number of async ops initiated per buf_daemon loop. This is 588 * somewhat of a hack at the moment, we really need to limit ourselves 589 * based on the number of bytes of I/O in-transit that were initiated 590 * from buf_daemon. 591 */ 592 593 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ | 594 VM_ALLOC_NORMAL | VM_ALLOC_WIRED); 595} 596 597/* 598 * bfreekva() - free the kva allocation for a buffer. 599 * 600 * Must be called at splbio() or higher as this is the only locking for 601 * buffer_map. 602 * 603 * Since this call frees up buffer space, we call bufspacewakeup(). 604 */ 605static void 606bfreekva(struct buf * bp) 607{ 608 GIANT_REQUIRED; 609 610 if (bp->b_kvasize) { 611 atomic_add_int(&buffreekvacnt, 1); 612 atomic_subtract_int(&bufspace, bp->b_kvasize); 613 vm_map_delete(buffer_map, 614 (vm_offset_t) bp->b_kvabase, 615 (vm_offset_t) bp->b_kvabase + bp->b_kvasize 616 ); 617 bp->b_kvasize = 0; 618 bufspacewakeup(); 619 } 620} 621 622/* 623 * bremfree: 624 * 625 * Remove the buffer from the appropriate free list. 626 */ 627void 628bremfree(struct buf * bp) 629{ 630 mtx_lock(&bqlock); 631 bremfreel(bp); 632 mtx_unlock(&bqlock); 633} 634 635void 636bremfreel(struct buf * bp) 637{ 638 int s = splbio(); 639 int old_qindex = bp->b_qindex; 640 641 GIANT_REQUIRED; 642 643 if (bp->b_qindex != QUEUE_NONE) { 644 KASSERT(BUF_REFCNT(bp) == 1, ("bremfree: bp %p not locked",bp)); 645 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 646 bp->b_qindex = QUEUE_NONE; 647 } else { 648 if (BUF_REFCNT(bp) <= 1) 649 panic("bremfree: removing a buffer not on a queue"); 650 } 651 652 /* 653 * Fixup numfreebuffers count. If the buffer is invalid or not 654 * delayed-write, and it was on the EMPTY, LRU, or AGE queues, 655 * the buffer was free and we must decrement numfreebuffers. 656 */ 657 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { 658 switch(old_qindex) { 659 case QUEUE_DIRTY: 660 case QUEUE_CLEAN: 661 case QUEUE_EMPTY: 662 case QUEUE_EMPTYKVA: 663 atomic_subtract_int(&numfreebuffers, 1); 664 break; 665 default: 666 break; 667 } 668 } 669 splx(s); 670} 671 672 673/* 674 * Get a buffer with the specified data. Look in the cache first. We 675 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 676 * is set, the buffer is valid and we do not have to do anything ( see 677 * getblk() ). This is really just a special case of breadn(). 678 */ 679int 680bread(struct vnode * vp, daddr_t blkno, int size, struct ucred * cred, 681 struct buf ** bpp) 682{ 683 684 return (breadn(vp, blkno, size, 0, 0, 0, cred, bpp)); 685} 686 687/* 688 * Operates like bread, but also starts asynchronous I/O on 689 * read-ahead blocks. We must clear BIO_ERROR and B_INVAL prior 690 * to initiating I/O . If B_CACHE is set, the buffer is valid 691 * and we do not have to do anything. 692 */ 693int 694breadn(struct vnode * vp, daddr_t blkno, int size, 695 daddr_t * rablkno, int *rabsize, 696 int cnt, struct ucred * cred, struct buf ** bpp) 697{ 698 struct buf *bp, *rabp; 699 int i; 700 int rv = 0, readwait = 0; 701 702 *bpp = bp = getblk(vp, blkno, size, 0, 0, 0); 703 704 /* if not found in cache, do some I/O */ 705 if ((bp->b_flags & B_CACHE) == 0) { 706 if (curthread != PCPU_GET(idlethread)) 707 curthread->td_proc->p_stats->p_ru.ru_inblock++; 708 bp->b_iocmd = BIO_READ; 709 bp->b_flags &= ~B_INVAL; 710 bp->b_ioflags &= ~BIO_ERROR; 711 if (bp->b_rcred == NOCRED && cred != NOCRED) 712 bp->b_rcred = crhold(cred); 713 vfs_busy_pages(bp, 0); 714 bp->b_iooffset = dbtob(bp->b_blkno); 715 if (vp->v_type == VCHR) 716 VOP_SPECSTRATEGY(vp, bp); 717 else 718 VOP_STRATEGY(vp, bp); 719 ++readwait; 720 } 721 722 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 723 if (inmem(vp, *rablkno)) 724 continue; 725 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 726 727 if ((rabp->b_flags & B_CACHE) == 0) { 728 if (curthread != PCPU_GET(idlethread)) 729 curthread->td_proc->p_stats->p_ru.ru_inblock++; 730 rabp->b_flags |= B_ASYNC; 731 rabp->b_flags &= ~B_INVAL; 732 rabp->b_ioflags &= ~BIO_ERROR; 733 rabp->b_iocmd = BIO_READ; 734 if (rabp->b_rcred == NOCRED && cred != NOCRED) 735 rabp->b_rcred = crhold(cred); 736 vfs_busy_pages(rabp, 0); 737 BUF_KERNPROC(rabp); 738 rabp->b_iooffset = dbtob(rabp->b_blkno); 739 if (vp->v_type == VCHR) 740 VOP_SPECSTRATEGY(vp, rabp); 741 else 742 VOP_STRATEGY(vp, rabp); 743 } else { 744 brelse(rabp); 745 } 746 } 747 748 if (readwait) { 749 rv = bufwait(bp); 750 } 751 return (rv); 752} 753 754/* 755 * Write, release buffer on completion. (Done by iodone 756 * if async). Do not bother writing anything if the buffer 757 * is invalid. 758 * 759 * Note that we set B_CACHE here, indicating that buffer is 760 * fully valid and thus cacheable. This is true even of NFS 761 * now so we set it generally. This could be set either here 762 * or in biodone() since the I/O is synchronous. We put it 763 * here. 764 */ 765int 766bwrite(struct buf * bp) 767{ 768 769 KASSERT(bp->b_op != NULL && bp->b_op->bop_write != NULL, 770 ("Martian buffer %p in bwrite: nobody to write it.", bp)); 771 return (bp->b_op->bop_write(bp)); 772} 773 774static int 775ibwrite(struct buf * bp) 776{ 777 int oldflags, s; 778 struct buf *newbp; 779 780 if (bp->b_flags & B_INVAL) { 781 brelse(bp); 782 return (0); 783 } 784 785 oldflags = bp->b_flags; 786 787 if (BUF_REFCNT(bp) == 0) 788 panic("ibwrite: buffer is not busy???"); 789 s = splbio(); 790 /* 791 * If a background write is already in progress, delay 792 * writing this block if it is asynchronous. Otherwise 793 * wait for the background write to complete. 794 */ 795 VI_LOCK(bp->b_vp); 796 if (bp->b_vflags & BV_BKGRDINPROG) { 797 if (bp->b_flags & B_ASYNC) { 798 VI_UNLOCK(bp->b_vp); 799 splx(s); 800 bdwrite(bp); 801 return (0); 802 } 803 bp->b_vflags |= BV_BKGRDWAIT; 804 msleep(&bp->b_xflags, VI_MTX(bp->b_vp), PRIBIO, "bwrbg", 0); 805 if (bp->b_vflags & BV_BKGRDINPROG) 806 panic("ibwrite: still writing"); 807 } 808 VI_UNLOCK(bp->b_vp); 809 810 /* Mark the buffer clean */ 811 bundirty(bp); 812 813 /* 814 * If this buffer is marked for background writing and we 815 * do not have to wait for it, make a copy and write the 816 * copy so as to leave this buffer ready for further use. 817 * 818 * This optimization eats a lot of memory. If we have a page 819 * or buffer shortfall we can't do it. 820 */ 821 if (dobkgrdwrite && (bp->b_xflags & BX_BKGRDWRITE) && 822 (bp->b_flags & B_ASYNC) && 823 !vm_page_count_severe() && 824 !buf_dirty_count_severe()) { 825 if (bp->b_iodone != NULL) { 826 printf("bp->b_iodone = %p\n", bp->b_iodone); 827 panic("ibwrite: need chained iodone"); 828 } 829 830 /* get a new block */ 831 newbp = geteblk(bp->b_bufsize); 832 833 /* 834 * set it to be identical to the old block. We have to 835 * set b_lblkno and BKGRDMARKER before calling bgetvp() 836 * to avoid confusing the splay tree and gbincore(). 837 */ 838 memcpy(newbp->b_data, bp->b_data, bp->b_bufsize); 839 newbp->b_lblkno = bp->b_lblkno; 840 newbp->b_xflags |= BX_BKGRDMARKER; 841 VI_LOCK(bp->b_vp); 842 bp->b_vflags |= BV_BKGRDINPROG; 843 bgetvp(bp->b_vp, newbp); 844 VI_UNLOCK(bp->b_vp); 845 newbp->b_blkno = bp->b_blkno; 846 newbp->b_offset = bp->b_offset; 847 newbp->b_iodone = vfs_backgroundwritedone; 848 newbp->b_flags |= B_ASYNC; 849 newbp->b_flags &= ~B_INVAL; 850 851 /* move over the dependencies */ 852 if (LIST_FIRST(&bp->b_dep) != NULL) 853 buf_movedeps(bp, newbp); 854 855 /* 856 * Initiate write on the copy, release the original to 857 * the B_LOCKED queue so that it cannot go away until 858 * the background write completes. If not locked it could go 859 * away and then be reconstituted while it was being written. 860 * If the reconstituted buffer were written, we could end up 861 * with two background copies being written at the same time. 862 */ 863 bqrelse(bp); 864 bp = newbp; 865 } 866 867 bp->b_flags &= ~B_DONE; 868 bp->b_ioflags &= ~BIO_ERROR; 869 bp->b_flags |= B_WRITEINPROG | B_CACHE; 870 bp->b_iocmd = BIO_WRITE; 871 872 VI_LOCK(bp->b_vp); 873 bp->b_vp->v_numoutput++; 874 VI_UNLOCK(bp->b_vp); 875 vfs_busy_pages(bp, 1); 876 877 /* 878 * Normal bwrites pipeline writes 879 */ 880 bp->b_runningbufspace = bp->b_bufsize; 881 atomic_add_int(&runningbufspace, bp->b_runningbufspace); 882 883 if (curthread != PCPU_GET(idlethread)) 884 curthread->td_proc->p_stats->p_ru.ru_oublock++; 885 splx(s); 886 if (oldflags & B_ASYNC) 887 BUF_KERNPROC(bp); 888 bp->b_iooffset = dbtob(bp->b_blkno); 889 if (bp->b_vp->v_type == VCHR) { 890 if (!buf_prewrite(bp->b_vp, bp)) 891 VOP_SPECSTRATEGY(bp->b_vp, bp); 892 } else { 893 VOP_STRATEGY(bp->b_vp, bp); 894 } 895 896 if ((oldflags & B_ASYNC) == 0) { 897 int rtval = bufwait(bp); 898 brelse(bp); 899 return (rtval); 900 } else { 901 /* 902 * don't allow the async write to saturate the I/O 903 * system. We will not deadlock here because 904 * we are blocking waiting for I/O that is already in-progress 905 * to complete. We do not block here if it is the update 906 * or syncer daemon trying to clean up as that can lead 907 * to deadlock. 908 */ 909 if (curthread->td_proc != bufdaemonproc && 910 curthread->td_proc != updateproc) 911 waitrunningbufspace(); 912 } 913 914 return (0); 915} 916 917/* 918 * Complete a background write started from bwrite. 919 */ 920static void 921vfs_backgroundwritedone(bp) 922 struct buf *bp; 923{ 924 struct buf *origbp; 925 926 /* 927 * Find the original buffer that we are writing. 928 */ 929 VI_LOCK(bp->b_vp); 930 if ((origbp = gbincore(bp->b_vp, bp->b_lblkno)) == NULL) 931 panic("backgroundwritedone: lost buffer"); 932 933 /* 934 * Clear the BV_BKGRDINPROG flag in the original buffer 935 * and awaken it if it is waiting for the write to complete. 936 * If BV_BKGRDINPROG is not set in the original buffer it must 937 * have been released and re-instantiated - which is not legal. 938 */ 939 KASSERT((origbp->b_vflags & BV_BKGRDINPROG), 940 ("backgroundwritedone: lost buffer2")); 941 origbp->b_vflags &= ~BV_BKGRDINPROG; 942 if (origbp->b_vflags & BV_BKGRDWAIT) { 943 origbp->b_vflags &= ~BV_BKGRDWAIT; 944 wakeup(&origbp->b_xflags); 945 } 946 VI_UNLOCK(bp->b_vp); 947 /* 948 * Process dependencies then return any unfinished ones. 949 */ 950 if (LIST_FIRST(&bp->b_dep) != NULL) 951 buf_complete(bp); 952 if (LIST_FIRST(&bp->b_dep) != NULL) 953 buf_movedeps(bp, origbp); 954 955 /* 956 * This buffer is marked B_NOCACHE, so when it is released 957 * by biodone, it will be tossed. We mark it with BIO_READ 958 * to avoid biodone doing a second vwakeup. 959 */ 960 bp->b_flags |= B_NOCACHE; 961 bp->b_iocmd = BIO_READ; 962 bp->b_flags &= ~(B_CACHE | B_DONE); 963 bp->b_iodone = 0; 964 bufdone(bp); 965} 966 967/* 968 * Delayed write. (Buffer is marked dirty). Do not bother writing 969 * anything if the buffer is marked invalid. 970 * 971 * Note that since the buffer must be completely valid, we can safely 972 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 973 * biodone() in order to prevent getblk from writing the buffer 974 * out synchronously. 975 */ 976void 977bdwrite(struct buf * bp) 978{ 979 struct thread *td = curthread; 980 struct vnode *vp; 981 struct buf *nbp; 982 983 GIANT_REQUIRED; 984 985 if (BUF_REFCNT(bp) == 0) 986 panic("bdwrite: buffer is not busy"); 987 988 if (bp->b_flags & B_INVAL) { 989 brelse(bp); 990 return; 991 } 992 993 /* 994 * If we have too many dirty buffers, don't create any more. 995 * If we are wildly over our limit, then force a complete 996 * cleanup. Otherwise, just keep the situation from getting 997 * out of control. Note that we have to avoid a recursive 998 * disaster and not try to clean up after our own cleanup! 999 */ 1000 vp = bp->b_vp; 1001 VI_LOCK(vp); 1002 if (td->td_pflags & TDP_COWINPROGRESS) { 1003 recursiveflushes++; 1004 } else if (vp != NULL && vp->v_dirtybufcnt > dirtybufthresh + 10) { 1005 VI_UNLOCK(vp); 1006 (void) VOP_FSYNC(vp, td->td_ucred, MNT_NOWAIT, td); 1007 VI_LOCK(vp); 1008 altbufferflushes++; 1009 } else if (vp != NULL && vp->v_dirtybufcnt > dirtybufthresh) { 1010 /* 1011 * Try to find a buffer to flush. 1012 */ 1013 TAILQ_FOREACH(nbp, &vp->v_dirtyblkhd, b_vnbufs) { 1014 if ((nbp->b_vflags & BV_BKGRDINPROG) || 1015 buf_countdeps(nbp, 0) || 1016 BUF_LOCK(nbp, LK_EXCLUSIVE | LK_NOWAIT, NULL)) 1017 continue; 1018 if (bp == nbp) 1019 panic("bdwrite: found ourselves"); 1020 VI_UNLOCK(vp); 1021 if (nbp->b_flags & B_CLUSTEROK) { 1022 vfs_bio_awrite(nbp); 1023 } else { 1024 bremfree(nbp); 1025 bawrite(nbp); 1026 } 1027 VI_LOCK(vp); 1028 dirtybufferflushes++; 1029 break; 1030 } 1031 } 1032 VI_UNLOCK(vp); 1033 1034 bdirty(bp); 1035 /* 1036 * Set B_CACHE, indicating that the buffer is fully valid. This is 1037 * true even of NFS now. 1038 */ 1039 bp->b_flags |= B_CACHE; 1040 1041 /* 1042 * This bmap keeps the system from needing to do the bmap later, 1043 * perhaps when the system is attempting to do a sync. Since it 1044 * is likely that the indirect block -- or whatever other datastructure 1045 * that the filesystem needs is still in memory now, it is a good 1046 * thing to do this. Note also, that if the pageout daemon is 1047 * requesting a sync -- there might not be enough memory to do 1048 * the bmap then... So, this is important to do. 1049 */ 1050 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 1051 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 1052 } 1053 1054 /* 1055 * Set the *dirty* buffer range based upon the VM system dirty pages. 1056 */ 1057 vfs_setdirty(bp); 1058 1059 /* 1060 * We need to do this here to satisfy the vnode_pager and the 1061 * pageout daemon, so that it thinks that the pages have been 1062 * "cleaned". Note that since the pages are in a delayed write 1063 * buffer -- the VFS layer "will" see that the pages get written 1064 * out on the next sync, or perhaps the cluster will be completed. 1065 */ 1066 vfs_clean_pages(bp); 1067 bqrelse(bp); 1068 1069 /* 1070 * Wakeup the buffer flushing daemon if we have a lot of dirty 1071 * buffers (midpoint between our recovery point and our stall 1072 * point). 1073 */ 1074 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 1075 1076 /* 1077 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 1078 * due to the softdep code. 1079 */ 1080} 1081 1082/* 1083 * bdirty: 1084 * 1085 * Turn buffer into delayed write request. We must clear BIO_READ and 1086 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 1087 * itself to properly update it in the dirty/clean lists. We mark it 1088 * B_DONE to ensure that any asynchronization of the buffer properly 1089 * clears B_DONE ( else a panic will occur later ). 1090 * 1091 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 1092 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 1093 * should only be called if the buffer is known-good. 1094 * 1095 * Since the buffer is not on a queue, we do not update the numfreebuffers 1096 * count. 1097 * 1098 * Must be called at splbio(). 1099 * The buffer must be on QUEUE_NONE. 1100 */ 1101void 1102bdirty(bp) 1103 struct buf *bp; 1104{ 1105 KASSERT(bp->b_qindex == QUEUE_NONE, 1106 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1107 bp->b_flags &= ~(B_RELBUF); 1108 bp->b_iocmd = BIO_WRITE; 1109 1110 if ((bp->b_flags & B_DELWRI) == 0) { 1111 bp->b_flags |= B_DONE | B_DELWRI; 1112 reassignbuf(bp); 1113 atomic_add_int(&numdirtybuffers, 1); 1114 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 1115 } 1116} 1117 1118/* 1119 * bundirty: 1120 * 1121 * Clear B_DELWRI for buffer. 1122 * 1123 * Since the buffer is not on a queue, we do not update the numfreebuffers 1124 * count. 1125 * 1126 * Must be called at splbio(). 1127 * The buffer must be on QUEUE_NONE. 1128 */ 1129 1130void 1131bundirty(bp) 1132 struct buf *bp; 1133{ 1134 KASSERT(bp->b_qindex == QUEUE_NONE, 1135 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1136 1137 if (bp->b_flags & B_DELWRI) { 1138 bp->b_flags &= ~B_DELWRI; 1139 reassignbuf(bp); 1140 atomic_subtract_int(&numdirtybuffers, 1); 1141 numdirtywakeup(lodirtybuffers); 1142 } 1143 /* 1144 * Since it is now being written, we can clear its deferred write flag. 1145 */ 1146 bp->b_flags &= ~B_DEFERRED; 1147} 1148 1149/* 1150 * bawrite: 1151 * 1152 * Asynchronous write. Start output on a buffer, but do not wait for 1153 * it to complete. The buffer is released when the output completes. 1154 * 1155 * bwrite() ( or the VOP routine anyway ) is responsible for handling 1156 * B_INVAL buffers. Not us. 1157 */ 1158void 1159bawrite(struct buf * bp) 1160{ 1161 bp->b_flags |= B_ASYNC; 1162 (void) bwrite(bp); 1163} 1164 1165/* 1166 * bwillwrite: 1167 * 1168 * Called prior to the locking of any vnodes when we are expecting to 1169 * write. We do not want to starve the buffer cache with too many 1170 * dirty buffers so we block here. By blocking prior to the locking 1171 * of any vnodes we attempt to avoid the situation where a locked vnode 1172 * prevents the various system daemons from flushing related buffers. 1173 */ 1174 1175void 1176bwillwrite(void) 1177{ 1178 if (numdirtybuffers >= hidirtybuffers) { 1179 int s; 1180 1181 mtx_lock(&Giant); 1182 s = splbio(); 1183 mtx_lock(&nblock); 1184 while (numdirtybuffers >= hidirtybuffers) { 1185 bd_wakeup(1); 1186 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH; 1187 msleep(&needsbuffer, &nblock, 1188 (PRIBIO + 4), "flswai", 0); 1189 } 1190 splx(s); 1191 mtx_unlock(&nblock); 1192 mtx_unlock(&Giant); 1193 } 1194} 1195 1196/* 1197 * Return true if we have too many dirty buffers. 1198 */ 1199int 1200buf_dirty_count_severe(void) 1201{ 1202 return(numdirtybuffers >= hidirtybuffers); 1203} 1204 1205/* 1206 * brelse: 1207 * 1208 * Release a busy buffer and, if requested, free its resources. The 1209 * buffer will be stashed in the appropriate bufqueue[] allowing it 1210 * to be accessed later as a cache entity or reused for other purposes. 1211 */ 1212void 1213brelse(struct buf * bp) 1214{ 1215 int s; 1216 1217 GIANT_REQUIRED; 1218 1219 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1220 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1221 1222 s = splbio(); 1223 1224 if (bp->b_iocmd == BIO_WRITE && 1225 (bp->b_ioflags & BIO_ERROR) && 1226 !(bp->b_flags & B_INVAL)) { 1227 /* 1228 * Failed write, redirty. Must clear BIO_ERROR to prevent 1229 * pages from being scrapped. If B_INVAL is set then 1230 * this case is not run and the next case is run to 1231 * destroy the buffer. B_INVAL can occur if the buffer 1232 * is outside the range supported by the underlying device. 1233 */ 1234 bp->b_ioflags &= ~BIO_ERROR; 1235 bdirty(bp); 1236 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 1237 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 1238 /* 1239 * Either a failed I/O or we were asked to free or not 1240 * cache the buffer. 1241 */ 1242 bp->b_flags |= B_INVAL; 1243 if (LIST_FIRST(&bp->b_dep) != NULL) 1244 buf_deallocate(bp); 1245 if (bp->b_flags & B_DELWRI) { 1246 atomic_subtract_int(&numdirtybuffers, 1); 1247 numdirtywakeup(lodirtybuffers); 1248 } 1249 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1250 if ((bp->b_flags & B_VMIO) == 0) { 1251 if (bp->b_bufsize) 1252 allocbuf(bp, 0); 1253 if (bp->b_vp) 1254 brelvp(bp); 1255 } 1256 } 1257 1258 /* 1259 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1260 * is called with B_DELWRI set, the underlying pages may wind up 1261 * getting freed causing a previous write (bdwrite()) to get 'lost' 1262 * because pages associated with a B_DELWRI bp are marked clean. 1263 * 1264 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1265 * if B_DELWRI is set. 1266 * 1267 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1268 * on pages to return pages to the VM page queues. 1269 */ 1270 if (bp->b_flags & B_DELWRI) 1271 bp->b_flags &= ~B_RELBUF; 1272 else if (vm_page_count_severe()) { 1273 /* 1274 * XXX This lock may not be necessary since BKGRDINPROG 1275 * cannot be set while we hold the buf lock, it can only be 1276 * cleared if it is already pending. 1277 */ 1278 if (bp->b_vp) { 1279 VI_LOCK(bp->b_vp); 1280 if (!(bp->b_vflags & BV_BKGRDINPROG)) 1281 bp->b_flags |= B_RELBUF; 1282 VI_UNLOCK(bp->b_vp); 1283 } else 1284 bp->b_flags |= B_RELBUF; 1285 } 1286 1287 /* 1288 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1289 * constituted, not even NFS buffers now. Two flags effect this. If 1290 * B_INVAL, the struct buf is invalidated but the VM object is kept 1291 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1292 * 1293 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 1294 * invalidated. BIO_ERROR cannot be set for a failed write unless the 1295 * buffer is also B_INVAL because it hits the re-dirtying code above. 1296 * 1297 * Normally we can do this whether a buffer is B_DELWRI or not. If 1298 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1299 * the commit state and we cannot afford to lose the buffer. If the 1300 * buffer has a background write in progress, we need to keep it 1301 * around to prevent it from being reconstituted and starting a second 1302 * background write. 1303 */ 1304 if ((bp->b_flags & B_VMIO) 1305 && !(bp->b_vp->v_mount != NULL && 1306 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 1307 !vn_isdisk(bp->b_vp, NULL) && 1308 (bp->b_flags & B_DELWRI)) 1309 ) { 1310 1311 int i, j, resid; 1312 vm_page_t m; 1313 off_t foff; 1314 vm_pindex_t poff; 1315 vm_object_t obj; 1316 1317 obj = bp->b_object; 1318 1319 /* 1320 * Get the base offset and length of the buffer. Note that 1321 * in the VMIO case if the buffer block size is not 1322 * page-aligned then b_data pointer may not be page-aligned. 1323 * But our b_pages[] array *IS* page aligned. 1324 * 1325 * block sizes less then DEV_BSIZE (usually 512) are not 1326 * supported due to the page granularity bits (m->valid, 1327 * m->dirty, etc...). 1328 * 1329 * See man buf(9) for more information 1330 */ 1331 resid = bp->b_bufsize; 1332 foff = bp->b_offset; 1333 VM_OBJECT_LOCK(obj); 1334 for (i = 0; i < bp->b_npages; i++) { 1335 int had_bogus = 0; 1336 1337 m = bp->b_pages[i]; 1338 1339 /* 1340 * If we hit a bogus page, fixup *all* the bogus pages 1341 * now. 1342 */ 1343 if (m == bogus_page) { 1344 poff = OFF_TO_IDX(bp->b_offset); 1345 had_bogus = 1; 1346 1347 for (j = i; j < bp->b_npages; j++) { 1348 vm_page_t mtmp; 1349 mtmp = bp->b_pages[j]; 1350 if (mtmp == bogus_page) { 1351 mtmp = vm_page_lookup(obj, poff + j); 1352 if (!mtmp) { 1353 panic("brelse: page missing\n"); 1354 } 1355 bp->b_pages[j] = mtmp; 1356 } 1357 } 1358 1359 if ((bp->b_flags & B_INVAL) == 0) { 1360 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 1361 } 1362 m = bp->b_pages[i]; 1363 } 1364 if ((bp->b_flags & B_NOCACHE) || (bp->b_ioflags & BIO_ERROR)) { 1365 int poffset = foff & PAGE_MASK; 1366 int presid = resid > (PAGE_SIZE - poffset) ? 1367 (PAGE_SIZE - poffset) : resid; 1368 1369 KASSERT(presid >= 0, ("brelse: extra page")); 1370 vm_page_lock_queues(); 1371 vm_page_set_invalid(m, poffset, presid); 1372 vm_page_unlock_queues(); 1373 if (had_bogus) 1374 printf("avoided corruption bug in bogus_page/brelse code\n"); 1375 } 1376 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1377 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1378 } 1379 VM_OBJECT_UNLOCK(obj); 1380 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1381 vfs_vmio_release(bp); 1382 1383 } else if (bp->b_flags & B_VMIO) { 1384 1385 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1386 vfs_vmio_release(bp); 1387 } 1388 1389 } 1390 1391 if (bp->b_qindex != QUEUE_NONE) 1392 panic("brelse: free buffer onto another queue???"); 1393 if (BUF_REFCNT(bp) > 1) { 1394 /* do not release to free list */ 1395 BUF_UNLOCK(bp); 1396 splx(s); 1397 return; 1398 } 1399 1400 /* enqueue */ 1401 mtx_lock(&bqlock); 1402 1403 /* buffers with no memory */ 1404 if (bp->b_bufsize == 0) { 1405 bp->b_flags |= B_INVAL; 1406 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1407 if (bp->b_vflags & BV_BKGRDINPROG) 1408 panic("losing buffer 1"); 1409 if (bp->b_kvasize) { 1410 bp->b_qindex = QUEUE_EMPTYKVA; 1411 } else { 1412 bp->b_qindex = QUEUE_EMPTY; 1413 } 1414 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1415 bp->b_dev = NULL; 1416 /* buffers with junk contents */ 1417 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 1418 (bp->b_ioflags & BIO_ERROR)) { 1419 bp->b_flags |= B_INVAL; 1420 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1421 if (bp->b_vflags & BV_BKGRDINPROG) 1422 panic("losing buffer 2"); 1423 bp->b_qindex = QUEUE_CLEAN; 1424 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1425 bp->b_dev = NULL; 1426 /* remaining buffers */ 1427 } else { 1428 if (bp->b_flags & B_DELWRI) 1429 bp->b_qindex = QUEUE_DIRTY; 1430 else 1431 bp->b_qindex = QUEUE_CLEAN; 1432 if (bp->b_flags & B_AGE) 1433 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1434 else 1435 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1436 } 1437 mtx_unlock(&bqlock); 1438 1439 /* 1440 * If B_INVAL and B_DELWRI is set, clear B_DELWRI. We have already 1441 * placed the buffer on the correct queue. We must also disassociate 1442 * the device and vnode for a B_INVAL buffer so gbincore() doesn't 1443 * find it. 1444 */ 1445 if (bp->b_flags & B_INVAL) { 1446 if (bp->b_flags & B_DELWRI) 1447 bundirty(bp); 1448 if (bp->b_vp) 1449 brelvp(bp); 1450 } 1451 1452 /* 1453 * Fixup numfreebuffers count. The bp is on an appropriate queue 1454 * unless locked. We then bump numfreebuffers if it is not B_DELWRI. 1455 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1456 * if B_INVAL is set ). 1457 */ 1458 1459 if (!(bp->b_flags & B_DELWRI)) 1460 bufcountwakeup(); 1461 1462 /* 1463 * Something we can maybe free or reuse 1464 */ 1465 if (bp->b_bufsize || bp->b_kvasize) 1466 bufspacewakeup(); 1467 1468 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 1469 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1470 panic("brelse: not dirty"); 1471 /* unlock */ 1472 BUF_UNLOCK(bp); 1473 splx(s); 1474} 1475 1476/* 1477 * Release a buffer back to the appropriate queue but do not try to free 1478 * it. The buffer is expected to be used again soon. 1479 * 1480 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1481 * biodone() to requeue an async I/O on completion. It is also used when 1482 * known good buffers need to be requeued but we think we may need the data 1483 * again soon. 1484 * 1485 * XXX we should be able to leave the B_RELBUF hint set on completion. 1486 */ 1487void 1488bqrelse(struct buf * bp) 1489{ 1490 int s; 1491 1492 s = splbio(); 1493 1494 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1495 1496 if (bp->b_qindex != QUEUE_NONE) 1497 panic("bqrelse: free buffer onto another queue???"); 1498 if (BUF_REFCNT(bp) > 1) { 1499 /* do not release to free list */ 1500 BUF_UNLOCK(bp); 1501 splx(s); 1502 return; 1503 } 1504 mtx_lock(&bqlock); 1505 /* buffers with stale but valid contents */ 1506 if (bp->b_flags & B_DELWRI) { 1507 bp->b_qindex = QUEUE_DIRTY; 1508 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist); 1509 } else { 1510 /* 1511 * XXX This lock may not be necessary since BKGRDINPROG 1512 * cannot be set while we hold the buf lock, it can only be 1513 * cleared if it is already pending. 1514 */ 1515 VI_LOCK(bp->b_vp); 1516 if (!vm_page_count_severe() || bp->b_vflags & BV_BKGRDINPROG) { 1517 VI_UNLOCK(bp->b_vp); 1518 bp->b_qindex = QUEUE_CLEAN; 1519 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, 1520 b_freelist); 1521 } else { 1522 /* 1523 * We are too low on memory, we have to try to free 1524 * the buffer (most importantly: the wired pages 1525 * making up its backing store) *now*. 1526 */ 1527 VI_UNLOCK(bp->b_vp); 1528 mtx_unlock(&bqlock); 1529 splx(s); 1530 brelse(bp); 1531 return; 1532 } 1533 } 1534 mtx_unlock(&bqlock); 1535 1536 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI)) 1537 bufcountwakeup(); 1538 1539 /* 1540 * Something we can maybe free or reuse. 1541 */ 1542 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1543 bufspacewakeup(); 1544 1545 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1546 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1547 panic("bqrelse: not dirty"); 1548 /* unlock */ 1549 BUF_UNLOCK(bp); 1550 splx(s); 1551} 1552 1553/* Give pages used by the bp back to the VM system (where possible) */ 1554static void 1555vfs_vmio_release(bp) 1556 struct buf *bp; 1557{ 1558 int i; 1559 vm_page_t m; 1560 1561 GIANT_REQUIRED; 1562 VM_OBJECT_LOCK(bp->b_object); 1563 vm_page_lock_queues(); 1564 for (i = 0; i < bp->b_npages; i++) { 1565 m = bp->b_pages[i]; 1566 bp->b_pages[i] = NULL; 1567 /* 1568 * In order to keep page LRU ordering consistent, put 1569 * everything on the inactive queue. 1570 */ 1571 vm_page_unwire(m, 0); 1572 /* 1573 * We don't mess with busy pages, it is 1574 * the responsibility of the process that 1575 * busied the pages to deal with them. 1576 */ 1577 if ((m->flags & PG_BUSY) || (m->busy != 0)) 1578 continue; 1579 1580 if (m->wire_count == 0) { 1581 /* 1582 * Might as well free the page if we can and it has 1583 * no valid data. We also free the page if the 1584 * buffer was used for direct I/O 1585 */ 1586 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && 1587 m->hold_count == 0) { 1588 vm_page_busy(m); 1589 pmap_remove_all(m); 1590 vm_page_free(m); 1591 } else if (bp->b_flags & B_DIRECT) { 1592 vm_page_try_to_free(m); 1593 } else if (vm_page_count_severe()) { 1594 vm_page_try_to_cache(m); 1595 } 1596 } 1597 } 1598 vm_page_unlock_queues(); 1599 VM_OBJECT_UNLOCK(bp->b_object); 1600 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages); 1601 1602 if (bp->b_bufsize) { 1603 bufspacewakeup(); 1604 bp->b_bufsize = 0; 1605 } 1606 bp->b_npages = 0; 1607 bp->b_flags &= ~B_VMIO; 1608 if (bp->b_vp) 1609 brelvp(bp); 1610} 1611 1612/* 1613 * Check to see if a block at a particular lbn is available for a clustered 1614 * write. 1615 */ 1616static int 1617vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 1618{ 1619 struct buf *bpa; 1620 int match; 1621 1622 match = 0; 1623 1624 /* If the buf isn't in core skip it */ 1625 if ((bpa = gbincore(vp, lblkno)) == NULL) 1626 return (0); 1627 1628 /* If the buf is busy we don't want to wait for it */ 1629 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1630 return (0); 1631 1632 /* Only cluster with valid clusterable delayed write buffers */ 1633 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 1634 (B_DELWRI | B_CLUSTEROK)) 1635 goto done; 1636 1637 if (bpa->b_bufsize != size) 1638 goto done; 1639 1640 /* 1641 * Check to see if it is in the expected place on disk and that the 1642 * block has been mapped. 1643 */ 1644 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 1645 match = 1; 1646done: 1647 BUF_UNLOCK(bpa); 1648 return (match); 1649} 1650 1651/* 1652 * vfs_bio_awrite: 1653 * 1654 * Implement clustered async writes for clearing out B_DELWRI buffers. 1655 * This is much better then the old way of writing only one buffer at 1656 * a time. Note that we may not be presented with the buffers in the 1657 * correct order, so we search for the cluster in both directions. 1658 */ 1659int 1660vfs_bio_awrite(struct buf * bp) 1661{ 1662 int i; 1663 int j; 1664 daddr_t lblkno = bp->b_lblkno; 1665 struct vnode *vp = bp->b_vp; 1666 int s; 1667 int ncl; 1668 int nwritten; 1669 int size; 1670 int maxcl; 1671 1672 s = splbio(); 1673 /* 1674 * right now we support clustered writing only to regular files. If 1675 * we find a clusterable block we could be in the middle of a cluster 1676 * rather then at the beginning. 1677 */ 1678 if ((vp->v_type == VREG) && 1679 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1680 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1681 1682 size = vp->v_mount->mnt_stat.f_iosize; 1683 maxcl = MAXPHYS / size; 1684 1685 VI_LOCK(vp); 1686 for (i = 1; i < maxcl; i++) 1687 if (vfs_bio_clcheck(vp, size, lblkno + i, 1688 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 1689 break; 1690 1691 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 1692 if (vfs_bio_clcheck(vp, size, lblkno - j, 1693 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 1694 break; 1695 1696 VI_UNLOCK(vp); 1697 --j; 1698 ncl = i + j; 1699 /* 1700 * this is a possible cluster write 1701 */ 1702 if (ncl != 1) { 1703 BUF_UNLOCK(bp); 1704 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl); 1705 splx(s); 1706 return nwritten; 1707 } 1708 } 1709 1710 bremfree(bp); 1711 bp->b_flags |= B_ASYNC; 1712 1713 splx(s); 1714 /* 1715 * default (old) behavior, writing out only one block 1716 * 1717 * XXX returns b_bufsize instead of b_bcount for nwritten? 1718 */ 1719 nwritten = bp->b_bufsize; 1720 (void) bwrite(bp); 1721 1722 return nwritten; 1723} 1724 1725/* 1726 * getnewbuf: 1727 * 1728 * Find and initialize a new buffer header, freeing up existing buffers 1729 * in the bufqueues as necessary. The new buffer is returned locked. 1730 * 1731 * Important: B_INVAL is not set. If the caller wishes to throw the 1732 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1733 * 1734 * We block if: 1735 * We have insufficient buffer headers 1736 * We have insufficient buffer space 1737 * buffer_map is too fragmented ( space reservation fails ) 1738 * If we have to flush dirty buffers ( but we try to avoid this ) 1739 * 1740 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1741 * Instead we ask the buf daemon to do it for us. We attempt to 1742 * avoid piecemeal wakeups of the pageout daemon. 1743 */ 1744 1745static struct buf * 1746getnewbuf(int slpflag, int slptimeo, int size, int maxsize) 1747{ 1748 struct buf *bp; 1749 struct buf *nbp; 1750 int defrag = 0; 1751 int nqindex; 1752 static int flushingbufs; 1753 1754 GIANT_REQUIRED; 1755 1756 /* 1757 * We can't afford to block since we might be holding a vnode lock, 1758 * which may prevent system daemons from running. We deal with 1759 * low-memory situations by proactively returning memory and running 1760 * async I/O rather then sync I/O. 1761 */ 1762 1763 atomic_add_int(&getnewbufcalls, 1); 1764 atomic_subtract_int(&getnewbufrestarts, 1); 1765restart: 1766 atomic_add_int(&getnewbufrestarts, 1); 1767 1768 /* 1769 * Setup for scan. If we do not have enough free buffers, 1770 * we setup a degenerate case that immediately fails. Note 1771 * that if we are specially marked process, we are allowed to 1772 * dip into our reserves. 1773 * 1774 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 1775 * 1776 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 1777 * However, there are a number of cases (defragging, reusing, ...) 1778 * where we cannot backup. 1779 */ 1780 mtx_lock(&bqlock); 1781 nqindex = QUEUE_EMPTYKVA; 1782 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 1783 1784 if (nbp == NULL) { 1785 /* 1786 * If no EMPTYKVA buffers and we are either 1787 * defragging or reusing, locate a CLEAN buffer 1788 * to free or reuse. If bufspace useage is low 1789 * skip this step so we can allocate a new buffer. 1790 */ 1791 if (defrag || bufspace >= lobufspace) { 1792 nqindex = QUEUE_CLEAN; 1793 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 1794 } 1795 1796 /* 1797 * If we could not find or were not allowed to reuse a 1798 * CLEAN buffer, check to see if it is ok to use an EMPTY 1799 * buffer. We can only use an EMPTY buffer if allocating 1800 * its KVA would not otherwise run us out of buffer space. 1801 */ 1802 if (nbp == NULL && defrag == 0 && 1803 bufspace + maxsize < hibufspace) { 1804 nqindex = QUEUE_EMPTY; 1805 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1806 } 1807 } 1808 1809 /* 1810 * Run scan, possibly freeing data and/or kva mappings on the fly 1811 * depending. 1812 */ 1813 1814 while ((bp = nbp) != NULL) { 1815 int qindex = nqindex; 1816 1817 /* 1818 * Calculate next bp ( we can only use it if we do not block 1819 * or do other fancy things ). 1820 */ 1821 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 1822 switch(qindex) { 1823 case QUEUE_EMPTY: 1824 nqindex = QUEUE_EMPTYKVA; 1825 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]))) 1826 break; 1827 /* FALLTHROUGH */ 1828 case QUEUE_EMPTYKVA: 1829 nqindex = QUEUE_CLEAN; 1830 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]))) 1831 break; 1832 /* FALLTHROUGH */ 1833 case QUEUE_CLEAN: 1834 /* 1835 * nbp is NULL. 1836 */ 1837 break; 1838 } 1839 } 1840 if (bp->b_vp) { 1841 VI_LOCK(bp->b_vp); 1842 if (bp->b_vflags & BV_BKGRDINPROG) { 1843 VI_UNLOCK(bp->b_vp); 1844 continue; 1845 } 1846 VI_UNLOCK(bp->b_vp); 1847 } 1848 1849 /* 1850 * Sanity Checks 1851 */ 1852 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp)); 1853 1854 /* 1855 * Note: we no longer distinguish between VMIO and non-VMIO 1856 * buffers. 1857 */ 1858 1859 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); 1860 1861 /* 1862 * If we are defragging then we need a buffer with 1863 * b_kvasize != 0. XXX this situation should no longer 1864 * occur, if defrag is non-zero the buffer's b_kvasize 1865 * should also be non-zero at this point. XXX 1866 */ 1867 if (defrag && bp->b_kvasize == 0) { 1868 printf("Warning: defrag empty buffer %p\n", bp); 1869 continue; 1870 } 1871 1872 /* 1873 * Start freeing the bp. This is somewhat involved. nbp 1874 * remains valid only for QUEUE_EMPTY[KVA] bp's. 1875 */ 1876 1877 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1878 panic("getnewbuf: locked buf"); 1879 bremfreel(bp); 1880 mtx_unlock(&bqlock); 1881 1882 if (qindex == QUEUE_CLEAN) { 1883 if (bp->b_flags & B_VMIO) { 1884 bp->b_flags &= ~B_ASYNC; 1885 vfs_vmio_release(bp); 1886 } 1887 if (bp->b_vp) 1888 brelvp(bp); 1889 } 1890 1891 /* 1892 * NOTE: nbp is now entirely invalid. We can only restart 1893 * the scan from this point on. 1894 * 1895 * Get the rest of the buffer freed up. b_kva* is still 1896 * valid after this operation. 1897 */ 1898 1899 if (bp->b_rcred != NOCRED) { 1900 crfree(bp->b_rcred); 1901 bp->b_rcred = NOCRED; 1902 } 1903 if (bp->b_wcred != NOCRED) { 1904 crfree(bp->b_wcred); 1905 bp->b_wcred = NOCRED; 1906 } 1907 if (LIST_FIRST(&bp->b_dep) != NULL) 1908 buf_deallocate(bp); 1909 if (bp->b_vflags & BV_BKGRDINPROG) 1910 panic("losing buffer 3"); 1911 1912 if (bp->b_bufsize) 1913 allocbuf(bp, 0); 1914 1915 bp->b_flags = 0; 1916 bp->b_ioflags = 0; 1917 bp->b_xflags = 0; 1918 bp->b_vflags = 0; 1919 bp->b_dev = NULL; 1920 bp->b_vp = NULL; 1921 bp->b_blkno = bp->b_lblkno = 0; 1922 bp->b_offset = NOOFFSET; 1923 bp->b_iodone = 0; 1924 bp->b_error = 0; 1925 bp->b_resid = 0; 1926 bp->b_bcount = 0; 1927 bp->b_npages = 0; 1928 bp->b_dirtyoff = bp->b_dirtyend = 0; 1929 bp->b_magic = B_MAGIC_BIO; 1930 bp->b_op = &buf_ops_bio; 1931 bp->b_object = NULL; 1932 1933 LIST_INIT(&bp->b_dep); 1934 1935 /* 1936 * If we are defragging then free the buffer. 1937 */ 1938 if (defrag) { 1939 bp->b_flags |= B_INVAL; 1940 bfreekva(bp); 1941 brelse(bp); 1942 defrag = 0; 1943 goto restart; 1944 } 1945 1946 /* 1947 * If we are overcomitted then recover the buffer and its 1948 * KVM space. This occurs in rare situations when multiple 1949 * processes are blocked in getnewbuf() or allocbuf(). 1950 */ 1951 if (bufspace >= hibufspace) 1952 flushingbufs = 1; 1953 if (flushingbufs && bp->b_kvasize != 0) { 1954 bp->b_flags |= B_INVAL; 1955 bfreekva(bp); 1956 brelse(bp); 1957 goto restart; 1958 } 1959 if (bufspace < lobufspace) 1960 flushingbufs = 0; 1961 break; 1962 } 1963 1964 /* 1965 * If we exhausted our list, sleep as appropriate. We may have to 1966 * wakeup various daemons and write out some dirty buffers. 1967 * 1968 * Generally we are sleeping due to insufficient buffer space. 1969 */ 1970 1971 if (bp == NULL) { 1972 int flags; 1973 char *waitmsg; 1974 1975 mtx_unlock(&bqlock); 1976 if (defrag) { 1977 flags = VFS_BIO_NEED_BUFSPACE; 1978 waitmsg = "nbufkv"; 1979 } else if (bufspace >= hibufspace) { 1980 waitmsg = "nbufbs"; 1981 flags = VFS_BIO_NEED_BUFSPACE; 1982 } else { 1983 waitmsg = "newbuf"; 1984 flags = VFS_BIO_NEED_ANY; 1985 } 1986 1987 bd_speedup(); /* heeeelp */ 1988 1989 mtx_lock(&nblock); 1990 needsbuffer |= flags; 1991 while (needsbuffer & flags) { 1992 if (msleep(&needsbuffer, &nblock, 1993 (PRIBIO + 4) | slpflag, waitmsg, slptimeo)) { 1994 mtx_unlock(&nblock); 1995 return (NULL); 1996 } 1997 } 1998 mtx_unlock(&nblock); 1999 } else { 2000 /* 2001 * We finally have a valid bp. We aren't quite out of the 2002 * woods, we still have to reserve kva space. In order 2003 * to keep fragmentation sane we only allocate kva in 2004 * BKVASIZE chunks. 2005 */ 2006 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2007 2008 if (maxsize != bp->b_kvasize) { 2009 vm_offset_t addr = 0; 2010 2011 bfreekva(bp); 2012 2013 if (vm_map_findspace(buffer_map, 2014 vm_map_min(buffer_map), maxsize, &addr)) { 2015 /* 2016 * Uh oh. Buffer map is to fragmented. We 2017 * must defragment the map. 2018 */ 2019 atomic_add_int(&bufdefragcnt, 1); 2020 defrag = 1; 2021 bp->b_flags |= B_INVAL; 2022 brelse(bp); 2023 goto restart; 2024 } 2025 if (addr) { 2026 vm_map_insert(buffer_map, NULL, 0, 2027 addr, addr + maxsize, 2028 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT); 2029 2030 bp->b_kvabase = (caddr_t) addr; 2031 bp->b_kvasize = maxsize; 2032 atomic_add_int(&bufspace, bp->b_kvasize); 2033 atomic_add_int(&bufreusecnt, 1); 2034 } 2035 } 2036 bp->b_saveaddr = bp->b_kvabase; 2037 bp->b_data = bp->b_saveaddr; 2038 } 2039 return(bp); 2040} 2041 2042/* 2043 * buf_daemon: 2044 * 2045 * buffer flushing daemon. Buffers are normally flushed by the 2046 * update daemon but if it cannot keep up this process starts to 2047 * take the load in an attempt to prevent getnewbuf() from blocking. 2048 */ 2049 2050static struct kproc_desc buf_kp = { 2051 "bufdaemon", 2052 buf_daemon, 2053 &bufdaemonproc 2054}; 2055SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp) 2056 2057static void 2058buf_daemon() 2059{ 2060 int s; 2061 2062 mtx_lock(&Giant); 2063 2064 /* 2065 * This process needs to be suspended prior to shutdown sync. 2066 */ 2067 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2068 SHUTDOWN_PRI_LAST); 2069 2070 /* 2071 * This process is allowed to take the buffer cache to the limit 2072 */ 2073 s = splbio(); 2074 mtx_lock(&bdlock); 2075 2076 for (;;) { 2077 bd_request = 0; 2078 mtx_unlock(&bdlock); 2079 2080 kthread_suspend_check(bufdaemonproc); 2081 2082 /* 2083 * Do the flush. Limit the amount of in-transit I/O we 2084 * allow to build up, otherwise we would completely saturate 2085 * the I/O system. Wakeup any waiting processes before we 2086 * normally would so they can run in parallel with our drain. 2087 */ 2088 while (numdirtybuffers > lodirtybuffers) { 2089 if (flushbufqueues(0) == 0) { 2090 /* 2091 * Could not find any buffers without rollback 2092 * dependencies, so just write the first one 2093 * in the hopes of eventually making progress. 2094 */ 2095 flushbufqueues(1); 2096 break; 2097 } 2098 waitrunningbufspace(); 2099 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2100 } 2101 2102 /* 2103 * Only clear bd_request if we have reached our low water 2104 * mark. The buf_daemon normally waits 1 second and 2105 * then incrementally flushes any dirty buffers that have 2106 * built up, within reason. 2107 * 2108 * If we were unable to hit our low water mark and couldn't 2109 * find any flushable buffers, we sleep half a second. 2110 * Otherwise we loop immediately. 2111 */ 2112 mtx_lock(&bdlock); 2113 if (numdirtybuffers <= lodirtybuffers) { 2114 /* 2115 * We reached our low water mark, reset the 2116 * request and sleep until we are needed again. 2117 * The sleep is just so the suspend code works. 2118 */ 2119 bd_request = 0; 2120 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 2121 } else { 2122 /* 2123 * We couldn't find any flushable dirty buffers but 2124 * still have too many dirty buffers, we 2125 * have to sleep and try again. (rare) 2126 */ 2127 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 2128 } 2129 } 2130} 2131 2132/* 2133 * flushbufqueues: 2134 * 2135 * Try to flush a buffer in the dirty queue. We must be careful to 2136 * free up B_INVAL buffers instead of write them, which NFS is 2137 * particularly sensitive to. 2138 */ 2139int flushwithdeps = 0; 2140SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 2141 0, "Number of buffers flushed with dependecies that require rollbacks"); 2142static int 2143flushbufqueues(int flushdeps) 2144{ 2145 struct thread *td = curthread; 2146 struct vnode *vp; 2147 struct mount *mp; 2148 struct buf *bp; 2149 int hasdeps; 2150 2151 mtx_lock(&bqlock); 2152 TAILQ_FOREACH(bp, &bufqueues[QUEUE_DIRTY], b_freelist) { 2153 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2154 continue; 2155 KASSERT((bp->b_flags & B_DELWRI), 2156 ("unexpected clean buffer %p", bp)); 2157 VI_LOCK(bp->b_vp); 2158 if ((bp->b_vflags & BV_BKGRDINPROG) != 0) { 2159 VI_UNLOCK(bp->b_vp); 2160 BUF_UNLOCK(bp); 2161 continue; 2162 } 2163 VI_UNLOCK(bp->b_vp); 2164 if (bp->b_flags & B_INVAL) { 2165 bremfreel(bp); 2166 mtx_unlock(&bqlock); 2167 brelse(bp); 2168 return (1); 2169 } 2170 2171 if (LIST_FIRST(&bp->b_dep) != NULL && buf_countdeps(bp, 0)) { 2172 if (flushdeps == 0) { 2173 BUF_UNLOCK(bp); 2174 continue; 2175 } 2176 hasdeps = 1; 2177 } else 2178 hasdeps = 0; 2179 /* 2180 * We must hold the lock on a vnode before writing 2181 * one of its buffers. Otherwise we may confuse, or 2182 * in the case of a snapshot vnode, deadlock the 2183 * system. 2184 * 2185 * The lock order here is the reverse of the normal 2186 * of vnode followed by buf lock. This is ok because 2187 * the NOWAIT will prevent deadlock. 2188 */ 2189 vp = bp->b_vp; 2190 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 2191 BUF_UNLOCK(bp); 2192 continue; 2193 } 2194 if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT, td) == 0) { 2195 mtx_unlock(&bqlock); 2196 vfs_bio_awrite(bp); 2197 vn_finished_write(mp); 2198 VOP_UNLOCK(vp, 0, td); 2199 flushwithdeps += hasdeps; 2200 return (1); 2201 } 2202 vn_finished_write(mp); 2203 BUF_UNLOCK(bp); 2204 } 2205 mtx_unlock(&bqlock); 2206 return (0); 2207} 2208 2209/* 2210 * Check to see if a block is currently memory resident. 2211 */ 2212struct buf * 2213incore(struct vnode * vp, daddr_t blkno) 2214{ 2215 struct buf *bp; 2216 2217 int s = splbio(); 2218 VI_LOCK(vp); 2219 bp = gbincore(vp, blkno); 2220 VI_UNLOCK(vp); 2221 splx(s); 2222 return (bp); 2223} 2224 2225/* 2226 * Returns true if no I/O is needed to access the 2227 * associated VM object. This is like incore except 2228 * it also hunts around in the VM system for the data. 2229 */ 2230 2231int 2232inmem(struct vnode * vp, daddr_t blkno) 2233{ 2234 vm_object_t obj; 2235 vm_offset_t toff, tinc, size; 2236 vm_page_t m; 2237 vm_ooffset_t off; 2238 2239 GIANT_REQUIRED; 2240 ASSERT_VOP_LOCKED(vp, "inmem"); 2241 2242 if (incore(vp, blkno)) 2243 return 1; 2244 if (vp->v_mount == NULL) 2245 return 0; 2246 if (VOP_GETVOBJECT(vp, &obj) != 0 || (vp->v_vflag & VV_OBJBUF) == 0) 2247 return 0; 2248 2249 size = PAGE_SIZE; 2250 if (size > vp->v_mount->mnt_stat.f_iosize) 2251 size = vp->v_mount->mnt_stat.f_iosize; 2252 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2253 2254 VM_OBJECT_LOCK(obj); 2255 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2256 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2257 if (!m) 2258 goto notinmem; 2259 tinc = size; 2260 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2261 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2262 if (vm_page_is_valid(m, 2263 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2264 goto notinmem; 2265 } 2266 VM_OBJECT_UNLOCK(obj); 2267 return 1; 2268 2269notinmem: 2270 VM_OBJECT_UNLOCK(obj); 2271 return (0); 2272} 2273 2274/* 2275 * vfs_setdirty: 2276 * 2277 * Sets the dirty range for a buffer based on the status of the dirty 2278 * bits in the pages comprising the buffer. 2279 * 2280 * The range is limited to the size of the buffer. 2281 * 2282 * This routine is primarily used by NFS, but is generalized for the 2283 * B_VMIO case. 2284 */ 2285static void 2286vfs_setdirty(struct buf *bp) 2287{ 2288 int i; 2289 vm_object_t object; 2290 2291 GIANT_REQUIRED; 2292 /* 2293 * Degenerate case - empty buffer 2294 */ 2295 2296 if (bp->b_bufsize == 0) 2297 return; 2298 2299 /* 2300 * We qualify the scan for modified pages on whether the 2301 * object has been flushed yet. The OBJ_WRITEABLE flag 2302 * is not cleared simply by protecting pages off. 2303 */ 2304 2305 if ((bp->b_flags & B_VMIO) == 0) 2306 return; 2307 2308 object = bp->b_pages[0]->object; 2309 VM_OBJECT_LOCK(object); 2310 if ((object->flags & OBJ_WRITEABLE) && !(object->flags & OBJ_MIGHTBEDIRTY)) 2311 printf("Warning: object %p writeable but not mightbedirty\n", object); 2312 if (!(object->flags & OBJ_WRITEABLE) && (object->flags & OBJ_MIGHTBEDIRTY)) 2313 printf("Warning: object %p mightbedirty but not writeable\n", object); 2314 2315 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) { 2316 vm_offset_t boffset; 2317 vm_offset_t eoffset; 2318 2319 vm_page_lock_queues(); 2320 /* 2321 * test the pages to see if they have been modified directly 2322 * by users through the VM system. 2323 */ 2324 for (i = 0; i < bp->b_npages; i++) 2325 vm_page_test_dirty(bp->b_pages[i]); 2326 2327 /* 2328 * Calculate the encompassing dirty range, boffset and eoffset, 2329 * (eoffset - boffset) bytes. 2330 */ 2331 2332 for (i = 0; i < bp->b_npages; i++) { 2333 if (bp->b_pages[i]->dirty) 2334 break; 2335 } 2336 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2337 2338 for (i = bp->b_npages - 1; i >= 0; --i) { 2339 if (bp->b_pages[i]->dirty) { 2340 break; 2341 } 2342 } 2343 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2344 2345 vm_page_unlock_queues(); 2346 /* 2347 * Fit it to the buffer. 2348 */ 2349 2350 if (eoffset > bp->b_bcount) 2351 eoffset = bp->b_bcount; 2352 2353 /* 2354 * If we have a good dirty range, merge with the existing 2355 * dirty range. 2356 */ 2357 2358 if (boffset < eoffset) { 2359 if (bp->b_dirtyoff > boffset) 2360 bp->b_dirtyoff = boffset; 2361 if (bp->b_dirtyend < eoffset) 2362 bp->b_dirtyend = eoffset; 2363 } 2364 } 2365 VM_OBJECT_UNLOCK(object); 2366} 2367 2368/* 2369 * getblk: 2370 * 2371 * Get a block given a specified block and offset into a file/device. 2372 * The buffers B_DONE bit will be cleared on return, making it almost 2373 * ready for an I/O initiation. B_INVAL may or may not be set on 2374 * return. The caller should clear B_INVAL prior to initiating a 2375 * READ. 2376 * 2377 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2378 * an existing buffer. 2379 * 2380 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2381 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2382 * and then cleared based on the backing VM. If the previous buffer is 2383 * non-0-sized but invalid, B_CACHE will be cleared. 2384 * 2385 * If getblk() must create a new buffer, the new buffer is returned with 2386 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2387 * case it is returned with B_INVAL clear and B_CACHE set based on the 2388 * backing VM. 2389 * 2390 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 2391 * B_CACHE bit is clear. 2392 * 2393 * What this means, basically, is that the caller should use B_CACHE to 2394 * determine whether the buffer is fully valid or not and should clear 2395 * B_INVAL prior to issuing a read. If the caller intends to validate 2396 * the buffer by loading its data area with something, the caller needs 2397 * to clear B_INVAL. If the caller does this without issuing an I/O, 2398 * the caller should set B_CACHE ( as an optimization ), else the caller 2399 * should issue the I/O and biodone() will set B_CACHE if the I/O was 2400 * a write attempt or if it was a successfull read. If the caller 2401 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 2402 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 2403 */ 2404struct buf * 2405getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo, 2406 int flags) 2407{ 2408 struct buf *bp; 2409 int s; 2410 int error; 2411 ASSERT_VOP_LOCKED(vp, "getblk"); 2412 2413 if (size > MAXBSIZE) 2414 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 2415 2416 s = splbio(); 2417loop: 2418 /* 2419 * Block if we are low on buffers. Certain processes are allowed 2420 * to completely exhaust the buffer cache. 2421 * 2422 * If this check ever becomes a bottleneck it may be better to 2423 * move it into the else, when gbincore() fails. At the moment 2424 * it isn't a problem. 2425 * 2426 * XXX remove if 0 sections (clean this up after its proven) 2427 */ 2428 if (numfreebuffers == 0) { 2429 if (curthread == PCPU_GET(idlethread)) 2430 return NULL; 2431 mtx_lock(&nblock); 2432 needsbuffer |= VFS_BIO_NEED_ANY; 2433 mtx_unlock(&nblock); 2434 } 2435 2436 VI_LOCK(vp); 2437 if ((bp = gbincore(vp, blkno))) { 2438 int lockflags; 2439 /* 2440 * Buffer is in-core. If the buffer is not busy, it must 2441 * be on a queue. 2442 */ 2443 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 2444 2445 if (flags & GB_LOCK_NOWAIT) 2446 lockflags |= LK_NOWAIT; 2447 2448 error = BUF_TIMELOCK(bp, lockflags, 2449 VI_MTX(vp), "getblk", slpflag, slptimeo); 2450 2451 /* 2452 * If we slept and got the lock we have to restart in case 2453 * the buffer changed identities. 2454 */ 2455 if (error == ENOLCK) 2456 goto loop; 2457 /* We timed out or were interrupted. */ 2458 else if (error) 2459 return (NULL); 2460 2461 /* 2462 * The buffer is locked. B_CACHE is cleared if the buffer is 2463 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 2464 * and for a VMIO buffer B_CACHE is adjusted according to the 2465 * backing VM cache. 2466 */ 2467 if (bp->b_flags & B_INVAL) 2468 bp->b_flags &= ~B_CACHE; 2469 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 2470 bp->b_flags |= B_CACHE; 2471 bremfree(bp); 2472 2473 /* 2474 * check for size inconsistancies for non-VMIO case. 2475 */ 2476 2477 if (bp->b_bcount != size) { 2478 if ((bp->b_flags & B_VMIO) == 0 || 2479 (size > bp->b_kvasize)) { 2480 if (bp->b_flags & B_DELWRI) { 2481 bp->b_flags |= B_NOCACHE; 2482 bwrite(bp); 2483 } else { 2484 if ((bp->b_flags & B_VMIO) && 2485 (LIST_FIRST(&bp->b_dep) == NULL)) { 2486 bp->b_flags |= B_RELBUF; 2487 brelse(bp); 2488 } else { 2489 bp->b_flags |= B_NOCACHE; 2490 bwrite(bp); 2491 } 2492 } 2493 goto loop; 2494 } 2495 } 2496 2497 /* 2498 * If the size is inconsistant in the VMIO case, we can resize 2499 * the buffer. This might lead to B_CACHE getting set or 2500 * cleared. If the size has not changed, B_CACHE remains 2501 * unchanged from its previous state. 2502 */ 2503 2504 if (bp->b_bcount != size) 2505 allocbuf(bp, size); 2506 2507 KASSERT(bp->b_offset != NOOFFSET, 2508 ("getblk: no buffer offset")); 2509 2510 /* 2511 * A buffer with B_DELWRI set and B_CACHE clear must 2512 * be committed before we can return the buffer in 2513 * order to prevent the caller from issuing a read 2514 * ( due to B_CACHE not being set ) and overwriting 2515 * it. 2516 * 2517 * Most callers, including NFS and FFS, need this to 2518 * operate properly either because they assume they 2519 * can issue a read if B_CACHE is not set, or because 2520 * ( for example ) an uncached B_DELWRI might loop due 2521 * to softupdates re-dirtying the buffer. In the latter 2522 * case, B_CACHE is set after the first write completes, 2523 * preventing further loops. 2524 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 2525 * above while extending the buffer, we cannot allow the 2526 * buffer to remain with B_CACHE set after the write 2527 * completes or it will represent a corrupt state. To 2528 * deal with this we set B_NOCACHE to scrap the buffer 2529 * after the write. 2530 * 2531 * We might be able to do something fancy, like setting 2532 * B_CACHE in bwrite() except if B_DELWRI is already set, 2533 * so the below call doesn't set B_CACHE, but that gets real 2534 * confusing. This is much easier. 2535 */ 2536 2537 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 2538 bp->b_flags |= B_NOCACHE; 2539 bwrite(bp); 2540 goto loop; 2541 } 2542 2543 splx(s); 2544 bp->b_flags &= ~B_DONE; 2545 } else { 2546 int bsize, maxsize, vmio; 2547 off_t offset; 2548 2549 /* 2550 * Buffer is not in-core, create new buffer. The buffer 2551 * returned by getnewbuf() is locked. Note that the returned 2552 * buffer is also considered valid (not marked B_INVAL). 2553 */ 2554 VI_UNLOCK(vp); 2555 /* 2556 * If the user does not want us to create the buffer, bail out 2557 * here. 2558 */ 2559 if (flags & GB_NOCREAT) { 2560 splx(s); 2561 return NULL; 2562 } 2563 if (vn_isdisk(vp, NULL)) 2564 bsize = DEV_BSIZE; 2565 else if (vp->v_mountedhere) 2566 bsize = vp->v_mountedhere->mnt_stat.f_iosize; 2567 else if (vp->v_mount) 2568 bsize = vp->v_mount->mnt_stat.f_iosize; 2569 else 2570 bsize = size; 2571 2572 if (vp->v_bsize != bsize) { 2573#if 0 2574 printf("WARNING: Wrong block size on vnode: %d should be %d\n", vp->v_bsize, bsize); 2575#endif 2576 vp->v_bsize = bsize; 2577 } 2578 2579 offset = blkno * bsize; 2580 vmio = (VOP_GETVOBJECT(vp, NULL) == 0) && 2581 (vp->v_vflag & VV_OBJBUF); 2582 maxsize = vmio ? size + (offset & PAGE_MASK) : size; 2583 maxsize = imax(maxsize, bsize); 2584 2585 if ((bp = getnewbuf(slpflag, slptimeo, size, maxsize)) == NULL) { 2586 if (slpflag || slptimeo) { 2587 splx(s); 2588 return NULL; 2589 } 2590 goto loop; 2591 } 2592 2593 /* 2594 * This code is used to make sure that a buffer is not 2595 * created while the getnewbuf routine is blocked. 2596 * This can be a problem whether the vnode is locked or not. 2597 * If the buffer is created out from under us, we have to 2598 * throw away the one we just created. There is now window 2599 * race because we are safely running at splbio() from the 2600 * point of the duplicate buffer creation through to here, 2601 * and we've locked the buffer. 2602 * 2603 * Note: this must occur before we associate the buffer 2604 * with the vp especially considering limitations in 2605 * the splay tree implementation when dealing with duplicate 2606 * lblkno's. 2607 */ 2608 VI_LOCK(vp); 2609 if (gbincore(vp, blkno)) { 2610 VI_UNLOCK(vp); 2611 bp->b_flags |= B_INVAL; 2612 brelse(bp); 2613 goto loop; 2614 } 2615 2616 /* 2617 * Insert the buffer into the hash, so that it can 2618 * be found by incore. 2619 */ 2620 bp->b_blkno = bp->b_lblkno = blkno; 2621 bp->b_offset = offset; 2622 2623 bgetvp(vp, bp); 2624 VI_UNLOCK(vp); 2625 2626 /* 2627 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 2628 * buffer size starts out as 0, B_CACHE will be set by 2629 * allocbuf() for the VMIO case prior to it testing the 2630 * backing store for validity. 2631 */ 2632 2633 if (vmio) { 2634 bp->b_flags |= B_VMIO; 2635#if defined(VFS_BIO_DEBUG) 2636 if (vn_canvmio(vp) != TRUE) 2637 printf("getblk: VMIO on vnode type %d\n", 2638 vp->v_type); 2639#endif 2640 VOP_GETVOBJECT(vp, &bp->b_object); 2641 } else { 2642 bp->b_flags &= ~B_VMIO; 2643 bp->b_object = NULL; 2644 } 2645 2646 allocbuf(bp, size); 2647 2648 splx(s); 2649 bp->b_flags &= ~B_DONE; 2650 } 2651 KASSERT(BUF_REFCNT(bp) == 1, ("getblk: bp %p not locked",bp)); 2652 return (bp); 2653} 2654 2655/* 2656 * Get an empty, disassociated buffer of given size. The buffer is initially 2657 * set to B_INVAL. 2658 */ 2659struct buf * 2660geteblk(int size) 2661{ 2662 struct buf *bp; 2663 int s; 2664 int maxsize; 2665 2666 maxsize = (size + BKVAMASK) & ~BKVAMASK; 2667 2668 s = splbio(); 2669 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0) 2670 continue; 2671 splx(s); 2672 allocbuf(bp, size); 2673 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 2674 KASSERT(BUF_REFCNT(bp) == 1, ("geteblk: bp %p not locked",bp)); 2675 return (bp); 2676} 2677 2678 2679/* 2680 * This code constitutes the buffer memory from either anonymous system 2681 * memory (in the case of non-VMIO operations) or from an associated 2682 * VM object (in the case of VMIO operations). This code is able to 2683 * resize a buffer up or down. 2684 * 2685 * Note that this code is tricky, and has many complications to resolve 2686 * deadlock or inconsistant data situations. Tread lightly!!! 2687 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 2688 * the caller. Calling this code willy nilly can result in the loss of data. 2689 * 2690 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 2691 * B_CACHE for the non-VMIO case. 2692 */ 2693 2694int 2695allocbuf(struct buf *bp, int size) 2696{ 2697 int newbsize, mbsize; 2698 int i; 2699 2700 GIANT_REQUIRED; 2701 2702 if (BUF_REFCNT(bp) == 0) 2703 panic("allocbuf: buffer not busy"); 2704 2705 if (bp->b_kvasize < size) 2706 panic("allocbuf: buffer too small"); 2707 2708 if ((bp->b_flags & B_VMIO) == 0) { 2709 caddr_t origbuf; 2710 int origbufsize; 2711 /* 2712 * Just get anonymous memory from the kernel. Don't 2713 * mess with B_CACHE. 2714 */ 2715 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2716 if (bp->b_flags & B_MALLOC) 2717 newbsize = mbsize; 2718 else 2719 newbsize = round_page(size); 2720 2721 if (newbsize < bp->b_bufsize) { 2722 /* 2723 * malloced buffers are not shrunk 2724 */ 2725 if (bp->b_flags & B_MALLOC) { 2726 if (newbsize) { 2727 bp->b_bcount = size; 2728 } else { 2729 free(bp->b_data, M_BIOBUF); 2730 if (bp->b_bufsize) { 2731 atomic_subtract_int( 2732 &bufmallocspace, 2733 bp->b_bufsize); 2734 bufspacewakeup(); 2735 bp->b_bufsize = 0; 2736 } 2737 bp->b_saveaddr = bp->b_kvabase; 2738 bp->b_data = bp->b_saveaddr; 2739 bp->b_bcount = 0; 2740 bp->b_flags &= ~B_MALLOC; 2741 } 2742 return 1; 2743 } 2744 vm_hold_free_pages( 2745 bp, 2746 (vm_offset_t) bp->b_data + newbsize, 2747 (vm_offset_t) bp->b_data + bp->b_bufsize); 2748 } else if (newbsize > bp->b_bufsize) { 2749 /* 2750 * We only use malloced memory on the first allocation. 2751 * and revert to page-allocated memory when the buffer 2752 * grows. 2753 */ 2754 /* 2755 * There is a potential smp race here that could lead 2756 * to bufmallocspace slightly passing the max. It 2757 * is probably extremely rare and not worth worrying 2758 * over. 2759 */ 2760 if ( (bufmallocspace < maxbufmallocspace) && 2761 (bp->b_bufsize == 0) && 2762 (mbsize <= PAGE_SIZE/2)) { 2763 2764 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 2765 bp->b_bufsize = mbsize; 2766 bp->b_bcount = size; 2767 bp->b_flags |= B_MALLOC; 2768 atomic_add_int(&bufmallocspace, mbsize); 2769 return 1; 2770 } 2771 origbuf = NULL; 2772 origbufsize = 0; 2773 /* 2774 * If the buffer is growing on its other-than-first allocation, 2775 * then we revert to the page-allocation scheme. 2776 */ 2777 if (bp->b_flags & B_MALLOC) { 2778 origbuf = bp->b_data; 2779 origbufsize = bp->b_bufsize; 2780 bp->b_data = bp->b_kvabase; 2781 if (bp->b_bufsize) { 2782 atomic_subtract_int(&bufmallocspace, 2783 bp->b_bufsize); 2784 bufspacewakeup(); 2785 bp->b_bufsize = 0; 2786 } 2787 bp->b_flags &= ~B_MALLOC; 2788 newbsize = round_page(newbsize); 2789 } 2790 vm_hold_load_pages( 2791 bp, 2792 (vm_offset_t) bp->b_data + bp->b_bufsize, 2793 (vm_offset_t) bp->b_data + newbsize); 2794 if (origbuf) { 2795 bcopy(origbuf, bp->b_data, origbufsize); 2796 free(origbuf, M_BIOBUF); 2797 } 2798 } 2799 } else { 2800 int desiredpages; 2801 2802 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2803 desiredpages = (size == 0) ? 0 : 2804 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 2805 2806 if (bp->b_flags & B_MALLOC) 2807 panic("allocbuf: VMIO buffer can't be malloced"); 2808 /* 2809 * Set B_CACHE initially if buffer is 0 length or will become 2810 * 0-length. 2811 */ 2812 if (size == 0 || bp->b_bufsize == 0) 2813 bp->b_flags |= B_CACHE; 2814 2815 if (newbsize < bp->b_bufsize) { 2816 /* 2817 * DEV_BSIZE aligned new buffer size is less then the 2818 * DEV_BSIZE aligned existing buffer size. Figure out 2819 * if we have to remove any pages. 2820 */ 2821 if (desiredpages < bp->b_npages) { 2822 vm_page_t m; 2823 2824 vm_page_lock_queues(); 2825 for (i = desiredpages; i < bp->b_npages; i++) { 2826 /* 2827 * the page is not freed here -- it 2828 * is the responsibility of 2829 * vnode_pager_setsize 2830 */ 2831 m = bp->b_pages[i]; 2832 KASSERT(m != bogus_page, 2833 ("allocbuf: bogus page found")); 2834 while (vm_page_sleep_if_busy(m, TRUE, "biodep")) 2835 vm_page_lock_queues(); 2836 2837 bp->b_pages[i] = NULL; 2838 vm_page_unwire(m, 0); 2839 } 2840 vm_page_unlock_queues(); 2841 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) + 2842 (desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages)); 2843 bp->b_npages = desiredpages; 2844 } 2845 } else if (size > bp->b_bcount) { 2846 /* 2847 * We are growing the buffer, possibly in a 2848 * byte-granular fashion. 2849 */ 2850 struct vnode *vp; 2851 vm_object_t obj; 2852 vm_offset_t toff; 2853 vm_offset_t tinc; 2854 2855 /* 2856 * Step 1, bring in the VM pages from the object, 2857 * allocating them if necessary. We must clear 2858 * B_CACHE if these pages are not valid for the 2859 * range covered by the buffer. 2860 */ 2861 2862 vp = bp->b_vp; 2863 obj = bp->b_object; 2864 2865 VM_OBJECT_LOCK(obj); 2866 while (bp->b_npages < desiredpages) { 2867 vm_page_t m; 2868 vm_pindex_t pi; 2869 2870 pi = OFF_TO_IDX(bp->b_offset) + bp->b_npages; 2871 if ((m = vm_page_lookup(obj, pi)) == NULL) { 2872 /* 2873 * note: must allocate system pages 2874 * since blocking here could intefere 2875 * with paging I/O, no matter which 2876 * process we are. 2877 */ 2878 m = vm_page_alloc(obj, pi, 2879 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED); 2880 if (m == NULL) { 2881 atomic_add_int(&vm_pageout_deficit, 2882 desiredpages - bp->b_npages); 2883 VM_OBJECT_UNLOCK(obj); 2884 VM_WAIT; 2885 VM_OBJECT_LOCK(obj); 2886 } else { 2887 vm_page_lock_queues(); 2888 vm_page_wakeup(m); 2889 vm_page_unlock_queues(); 2890 bp->b_flags &= ~B_CACHE; 2891 bp->b_pages[bp->b_npages] = m; 2892 ++bp->b_npages; 2893 } 2894 continue; 2895 } 2896 2897 /* 2898 * We found a page. If we have to sleep on it, 2899 * retry because it might have gotten freed out 2900 * from under us. 2901 * 2902 * We can only test PG_BUSY here. Blocking on 2903 * m->busy might lead to a deadlock: 2904 * 2905 * vm_fault->getpages->cluster_read->allocbuf 2906 * 2907 */ 2908 vm_page_lock_queues(); 2909 if (vm_page_sleep_if_busy(m, FALSE, "pgtblk")) 2910 continue; 2911 2912 /* 2913 * We have a good page. Should we wakeup the 2914 * page daemon? 2915 */ 2916 if ((curproc != pageproc) && 2917 ((m->queue - m->pc) == PQ_CACHE) && 2918 ((cnt.v_free_count + cnt.v_cache_count) < 2919 (cnt.v_free_min + cnt.v_cache_min))) { 2920 pagedaemon_wakeup(); 2921 } 2922 vm_page_wire(m); 2923 vm_page_unlock_queues(); 2924 bp->b_pages[bp->b_npages] = m; 2925 ++bp->b_npages; 2926 } 2927 2928 /* 2929 * Step 2. We've loaded the pages into the buffer, 2930 * we have to figure out if we can still have B_CACHE 2931 * set. Note that B_CACHE is set according to the 2932 * byte-granular range ( bcount and size ), new the 2933 * aligned range ( newbsize ). 2934 * 2935 * The VM test is against m->valid, which is DEV_BSIZE 2936 * aligned. Needless to say, the validity of the data 2937 * needs to also be DEV_BSIZE aligned. Note that this 2938 * fails with NFS if the server or some other client 2939 * extends the file's EOF. If our buffer is resized, 2940 * B_CACHE may remain set! XXX 2941 */ 2942 2943 toff = bp->b_bcount; 2944 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 2945 2946 while ((bp->b_flags & B_CACHE) && toff < size) { 2947 vm_pindex_t pi; 2948 2949 if (tinc > (size - toff)) 2950 tinc = size - toff; 2951 2952 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 2953 PAGE_SHIFT; 2954 2955 vfs_buf_test_cache( 2956 bp, 2957 bp->b_offset, 2958 toff, 2959 tinc, 2960 bp->b_pages[pi] 2961 ); 2962 toff += tinc; 2963 tinc = PAGE_SIZE; 2964 } 2965 VM_OBJECT_UNLOCK(obj); 2966 2967 /* 2968 * Step 3, fixup the KVM pmap. Remember that 2969 * bp->b_data is relative to bp->b_offset, but 2970 * bp->b_offset may be offset into the first page. 2971 */ 2972 2973 bp->b_data = (caddr_t) 2974 trunc_page((vm_offset_t)bp->b_data); 2975 pmap_qenter( 2976 (vm_offset_t)bp->b_data, 2977 bp->b_pages, 2978 bp->b_npages 2979 ); 2980 2981 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 2982 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 2983 } 2984 } 2985 if (newbsize < bp->b_bufsize) 2986 bufspacewakeup(); 2987 bp->b_bufsize = newbsize; /* actual buffer allocation */ 2988 bp->b_bcount = size; /* requested buffer size */ 2989 return 1; 2990} 2991 2992void 2993biodone(struct bio *bp) 2994{ 2995 mtx_lock(&bdonelock); 2996 bp->bio_flags |= BIO_DONE; 2997 if (bp->bio_done == NULL) 2998 wakeup(bp); 2999 mtx_unlock(&bdonelock); 3000 if (bp->bio_done != NULL) 3001 bp->bio_done(bp); 3002} 3003 3004/* 3005 * Wait for a BIO to finish. 3006 * 3007 * XXX: resort to a timeout for now. The optimal locking (if any) for this 3008 * case is not yet clear. 3009 */ 3010int 3011biowait(struct bio *bp, const char *wchan) 3012{ 3013 3014 mtx_lock(&bdonelock); 3015 while ((bp->bio_flags & BIO_DONE) == 0) 3016 msleep(bp, &bdonelock, PRIBIO, wchan, hz / 10); 3017 mtx_unlock(&bdonelock); 3018 if (bp->bio_error != 0) 3019 return (bp->bio_error); 3020 if (!(bp->bio_flags & BIO_ERROR)) 3021 return (0); 3022 return (EIO); 3023} 3024 3025void 3026biofinish(struct bio *bp, struct devstat *stat, int error) 3027{ 3028 3029 if (error) { 3030 bp->bio_error = error; 3031 bp->bio_flags |= BIO_ERROR; 3032 } 3033 if (stat != NULL) 3034 devstat_end_transaction_bio(stat, bp); 3035 biodone(bp); 3036} 3037 3038/* 3039 * bufwait: 3040 * 3041 * Wait for buffer I/O completion, returning error status. The buffer 3042 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3043 * error and cleared. 3044 */ 3045int 3046bufwait(register struct buf * bp) 3047{ 3048 int s; 3049 3050 s = splbio(); 3051 if (bp->b_iocmd == BIO_READ) 3052 bwait(bp, PRIBIO, "biord"); 3053 else 3054 bwait(bp, PRIBIO, "biowr"); 3055 splx(s); 3056 if (bp->b_flags & B_EINTR) { 3057 bp->b_flags &= ~B_EINTR; 3058 return (EINTR); 3059 } 3060 if (bp->b_ioflags & BIO_ERROR) { 3061 return (bp->b_error ? bp->b_error : EIO); 3062 } else { 3063 return (0); 3064 } 3065} 3066 3067 /* 3068 * Call back function from struct bio back up to struct buf. 3069 */ 3070static void 3071bufdonebio(struct bio *bp) 3072{ 3073 3074 /* Device drivers may or may not hold giant, hold it here. */ 3075 mtx_lock(&Giant); 3076 bufdone(bp->bio_caller2); 3077 mtx_unlock(&Giant); 3078} 3079 3080void 3081dev_strategy(struct buf *bp) 3082{ 3083 struct cdevsw *csw; 3084 3085 if ((!bp->b_iocmd) || (bp->b_iocmd & (bp->b_iocmd - 1))) 3086 panic("b_iocmd botch"); 3087 bp->b_io.bio_done = bufdonebio; 3088 bp->b_io.bio_caller2 = bp; 3089 csw = devsw(bp->b_io.bio_dev); 3090 KASSERT(bp->b_io.bio_dev->si_refcount > 0, 3091 ("dev_strategy on un-referenced struct cdev *(%s)", 3092 devtoname(bp->b_io.bio_dev))); 3093 cdevsw_ref(csw); 3094 (*devsw(bp->b_io.bio_dev)->d_strategy)(&bp->b_io); 3095 cdevsw_rel(csw); 3096} 3097 3098/* 3099 * bufdone: 3100 * 3101 * Finish I/O on a buffer, optionally calling a completion function. 3102 * This is usually called from an interrupt so process blocking is 3103 * not allowed. 3104 * 3105 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3106 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3107 * assuming B_INVAL is clear. 3108 * 3109 * For the VMIO case, we set B_CACHE if the op was a read and no 3110 * read error occured, or if the op was a write. B_CACHE is never 3111 * set if the buffer is invalid or otherwise uncacheable. 3112 * 3113 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3114 * initiator to leave B_INVAL set to brelse the buffer out of existance 3115 * in the biodone routine. 3116 */ 3117void 3118bufdone(struct buf *bp) 3119{ 3120 int s; 3121 void (*biodone)(struct buf *); 3122 3123 3124 s = splbio(); 3125 3126 KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp, BUF_REFCNT(bp))); 3127 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 3128 3129 bp->b_flags |= B_DONE; 3130 runningbufwakeup(bp); 3131 3132 if (bp->b_iocmd == BIO_WRITE) { 3133 vwakeup(bp); 3134 } 3135 3136 /* call optional completion function if requested */ 3137 if (bp->b_iodone != NULL) { 3138 biodone = bp->b_iodone; 3139 bp->b_iodone = NULL; 3140 (*biodone) (bp); 3141 splx(s); 3142 return; 3143 } 3144 if (LIST_FIRST(&bp->b_dep) != NULL) 3145 buf_complete(bp); 3146 3147 if (bp->b_flags & B_VMIO) { 3148 int i; 3149 vm_ooffset_t foff; 3150 vm_page_t m; 3151 vm_object_t obj; 3152 int iosize; 3153 struct vnode *vp = bp->b_vp; 3154 3155 obj = bp->b_object; 3156 3157#if defined(VFS_BIO_DEBUG) 3158 mp_fixme("usecount and vflag accessed without locks."); 3159 if (vp->v_usecount == 0) { 3160 panic("biodone: zero vnode ref count"); 3161 } 3162 3163 if ((vp->v_vflag & VV_OBJBUF) == 0) { 3164 panic("biodone: vnode is not setup for merged cache"); 3165 } 3166#endif 3167 3168 foff = bp->b_offset; 3169 KASSERT(bp->b_offset != NOOFFSET, 3170 ("biodone: no buffer offset")); 3171 3172 VM_OBJECT_LOCK(obj); 3173#if defined(VFS_BIO_DEBUG) 3174 if (obj->paging_in_progress < bp->b_npages) { 3175 printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n", 3176 obj->paging_in_progress, bp->b_npages); 3177 } 3178#endif 3179 3180 /* 3181 * Set B_CACHE if the op was a normal read and no error 3182 * occured. B_CACHE is set for writes in the b*write() 3183 * routines. 3184 */ 3185 iosize = bp->b_bcount - bp->b_resid; 3186 if (bp->b_iocmd == BIO_READ && 3187 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 3188 !(bp->b_ioflags & BIO_ERROR)) { 3189 bp->b_flags |= B_CACHE; 3190 } 3191 vm_page_lock_queues(); 3192 for (i = 0; i < bp->b_npages; i++) { 3193 int bogusflag = 0; 3194 int resid; 3195 3196 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 3197 if (resid > iosize) 3198 resid = iosize; 3199 3200 /* 3201 * cleanup bogus pages, restoring the originals 3202 */ 3203 m = bp->b_pages[i]; 3204 if (m == bogus_page) { 3205 bogusflag = 1; 3206 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3207 if (m == NULL) 3208 panic("biodone: page disappeared!"); 3209 bp->b_pages[i] = m; 3210 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 3211 } 3212#if defined(VFS_BIO_DEBUG) 3213 if (OFF_TO_IDX(foff) != m->pindex) { 3214 printf( 3215"biodone: foff(%jd)/m->pindex(%ju) mismatch\n", 3216 (intmax_t)foff, (uintmax_t)m->pindex); 3217 } 3218#endif 3219 3220 /* 3221 * In the write case, the valid and clean bits are 3222 * already changed correctly ( see bdwrite() ), so we 3223 * only need to do this here in the read case. 3224 */ 3225 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 3226 vfs_page_set_valid(bp, foff, i, m); 3227 } 3228 3229 /* 3230 * when debugging new filesystems or buffer I/O methods, this 3231 * is the most common error that pops up. if you see this, you 3232 * have not set the page busy flag correctly!!! 3233 */ 3234 if (m->busy == 0) { 3235 printf("biodone: page busy < 0, " 3236 "pindex: %d, foff: 0x(%x,%x), " 3237 "resid: %d, index: %d\n", 3238 (int) m->pindex, (int)(foff >> 32), 3239 (int) foff & 0xffffffff, resid, i); 3240 if (!vn_isdisk(vp, NULL)) 3241 printf(" iosize: %jd, lblkno: %jd, flags: 0x%x, npages: %d\n", 3242 (intmax_t)bp->b_vp->v_mount->mnt_stat.f_iosize, 3243 (intmax_t) bp->b_lblkno, 3244 bp->b_flags, bp->b_npages); 3245 else 3246 printf(" VDEV, lblkno: %jd, flags: 0x%x, npages: %d\n", 3247 (intmax_t) bp->b_lblkno, 3248 bp->b_flags, bp->b_npages); 3249 printf(" valid: 0x%lx, dirty: 0x%lx, wired: %d\n", 3250 (u_long)m->valid, (u_long)m->dirty, 3251 m->wire_count); 3252 panic("biodone: page busy < 0\n"); 3253 } 3254 vm_page_io_finish(m); 3255 vm_object_pip_subtract(obj, 1); 3256 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3257 iosize -= resid; 3258 } 3259 vm_page_unlock_queues(); 3260 vm_object_pip_wakeupn(obj, 0); 3261 VM_OBJECT_UNLOCK(obj); 3262 } 3263 3264 /* 3265 * For asynchronous completions, release the buffer now. The brelse 3266 * will do a wakeup there if necessary - so no need to do a wakeup 3267 * here in the async case. The sync case always needs to do a wakeup. 3268 */ 3269 3270 if (bp->b_flags & B_ASYNC) { 3271 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 3272 brelse(bp); 3273 else 3274 bqrelse(bp); 3275 } else { 3276 bdone(bp); 3277 } 3278 splx(s); 3279} 3280 3281/* 3282 * This routine is called in lieu of iodone in the case of 3283 * incomplete I/O. This keeps the busy status for pages 3284 * consistant. 3285 */ 3286void 3287vfs_unbusy_pages(struct buf * bp) 3288{ 3289 int i; 3290 3291 runningbufwakeup(bp); 3292 if (bp->b_flags & B_VMIO) { 3293 vm_object_t obj; 3294 3295 obj = bp->b_object; 3296 VM_OBJECT_LOCK(obj); 3297 vm_page_lock_queues(); 3298 for (i = 0; i < bp->b_npages; i++) { 3299 vm_page_t m = bp->b_pages[i]; 3300 3301 if (m == bogus_page) { 3302 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 3303 if (!m) { 3304 panic("vfs_unbusy_pages: page missing\n"); 3305 } 3306 bp->b_pages[i] = m; 3307 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 3308 } 3309 vm_object_pip_subtract(obj, 1); 3310 vm_page_io_finish(m); 3311 } 3312 vm_page_unlock_queues(); 3313 vm_object_pip_wakeupn(obj, 0); 3314 VM_OBJECT_UNLOCK(obj); 3315 } 3316} 3317 3318/* 3319 * vfs_page_set_valid: 3320 * 3321 * Set the valid bits in a page based on the supplied offset. The 3322 * range is restricted to the buffer's size. 3323 * 3324 * This routine is typically called after a read completes. 3325 */ 3326static void 3327vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m) 3328{ 3329 vm_ooffset_t soff, eoff; 3330 3331 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 3332 /* 3333 * Start and end offsets in buffer. eoff - soff may not cross a 3334 * page boundry or cross the end of the buffer. The end of the 3335 * buffer, in this case, is our file EOF, not the allocation size 3336 * of the buffer. 3337 */ 3338 soff = off; 3339 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3340 if (eoff > bp->b_offset + bp->b_bcount) 3341 eoff = bp->b_offset + bp->b_bcount; 3342 3343 /* 3344 * Set valid range. This is typically the entire buffer and thus the 3345 * entire page. 3346 */ 3347 if (eoff > soff) { 3348 vm_page_set_validclean( 3349 m, 3350 (vm_offset_t) (soff & PAGE_MASK), 3351 (vm_offset_t) (eoff - soff) 3352 ); 3353 } 3354} 3355 3356/* 3357 * This routine is called before a device strategy routine. 3358 * It is used to tell the VM system that paging I/O is in 3359 * progress, and treat the pages associated with the buffer 3360 * almost as being PG_BUSY. Also the object paging_in_progress 3361 * flag is handled to make sure that the object doesn't become 3362 * inconsistant. 3363 * 3364 * Since I/O has not been initiated yet, certain buffer flags 3365 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 3366 * and should be ignored. 3367 */ 3368void 3369vfs_busy_pages(struct buf * bp, int clear_modify) 3370{ 3371 int i, bogus; 3372 3373 if (bp->b_flags & B_VMIO) { 3374 vm_object_t obj; 3375 vm_ooffset_t foff; 3376 3377 obj = bp->b_object; 3378 foff = bp->b_offset; 3379 KASSERT(bp->b_offset != NOOFFSET, 3380 ("vfs_busy_pages: no buffer offset")); 3381 vfs_setdirty(bp); 3382 VM_OBJECT_LOCK(obj); 3383retry: 3384 vm_page_lock_queues(); 3385 for (i = 0; i < bp->b_npages; i++) { 3386 vm_page_t m = bp->b_pages[i]; 3387 3388 if (vm_page_sleep_if_busy(m, FALSE, "vbpage")) 3389 goto retry; 3390 } 3391 bogus = 0; 3392 for (i = 0; i < bp->b_npages; i++) { 3393 vm_page_t m = bp->b_pages[i]; 3394 3395 if ((bp->b_flags & B_CLUSTER) == 0) { 3396 vm_object_pip_add(obj, 1); 3397 vm_page_io_start(m); 3398 } 3399 /* 3400 * When readying a buffer for a read ( i.e 3401 * clear_modify == 0 ), it is important to do 3402 * bogus_page replacement for valid pages in 3403 * partially instantiated buffers. Partially 3404 * instantiated buffers can, in turn, occur when 3405 * reconstituting a buffer from its VM backing store 3406 * base. We only have to do this if B_CACHE is 3407 * clear ( which causes the I/O to occur in the 3408 * first place ). The replacement prevents the read 3409 * I/O from overwriting potentially dirty VM-backed 3410 * pages. XXX bogus page replacement is, uh, bogus. 3411 * It may not work properly with small-block devices. 3412 * We need to find a better way. 3413 */ 3414 pmap_remove_all(m); 3415 if (clear_modify) 3416 vfs_page_set_valid(bp, foff, i, m); 3417 else if (m->valid == VM_PAGE_BITS_ALL && 3418 (bp->b_flags & B_CACHE) == 0) { 3419 bp->b_pages[i] = bogus_page; 3420 bogus++; 3421 } 3422 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3423 } 3424 vm_page_unlock_queues(); 3425 VM_OBJECT_UNLOCK(obj); 3426 if (bogus) 3427 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 3428 } 3429} 3430 3431/* 3432 * Tell the VM system that the pages associated with this buffer 3433 * are clean. This is used for delayed writes where the data is 3434 * going to go to disk eventually without additional VM intevention. 3435 * 3436 * Note that while we only really need to clean through to b_bcount, we 3437 * just go ahead and clean through to b_bufsize. 3438 */ 3439static void 3440vfs_clean_pages(struct buf * bp) 3441{ 3442 int i; 3443 3444 if (bp->b_flags & B_VMIO) { 3445 vm_ooffset_t foff; 3446 3447 foff = bp->b_offset; 3448 KASSERT(bp->b_offset != NOOFFSET, 3449 ("vfs_clean_pages: no buffer offset")); 3450 VM_OBJECT_LOCK(bp->b_object); 3451 vm_page_lock_queues(); 3452 for (i = 0; i < bp->b_npages; i++) { 3453 vm_page_t m = bp->b_pages[i]; 3454 vm_ooffset_t noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3455 vm_ooffset_t eoff = noff; 3456 3457 if (eoff > bp->b_offset + bp->b_bufsize) 3458 eoff = bp->b_offset + bp->b_bufsize; 3459 vfs_page_set_valid(bp, foff, i, m); 3460 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3461 foff = noff; 3462 } 3463 vm_page_unlock_queues(); 3464 VM_OBJECT_UNLOCK(bp->b_object); 3465 } 3466} 3467 3468/* 3469 * vfs_bio_set_validclean: 3470 * 3471 * Set the range within the buffer to valid and clean. The range is 3472 * relative to the beginning of the buffer, b_offset. Note that b_offset 3473 * itself may be offset from the beginning of the first page. 3474 * 3475 */ 3476 3477void 3478vfs_bio_set_validclean(struct buf *bp, int base, int size) 3479{ 3480 if (bp->b_flags & B_VMIO) { 3481 int i; 3482 int n; 3483 3484 /* 3485 * Fixup base to be relative to beginning of first page. 3486 * Set initial n to be the maximum number of bytes in the 3487 * first page that can be validated. 3488 */ 3489 3490 base += (bp->b_offset & PAGE_MASK); 3491 n = PAGE_SIZE - (base & PAGE_MASK); 3492 3493 VM_OBJECT_LOCK(bp->b_object); 3494 vm_page_lock_queues(); 3495 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 3496 vm_page_t m = bp->b_pages[i]; 3497 3498 if (n > size) 3499 n = size; 3500 3501 vm_page_set_validclean(m, base & PAGE_MASK, n); 3502 base += n; 3503 size -= n; 3504 n = PAGE_SIZE; 3505 } 3506 vm_page_unlock_queues(); 3507 VM_OBJECT_UNLOCK(bp->b_object); 3508 } 3509} 3510 3511/* 3512 * vfs_bio_clrbuf: 3513 * 3514 * clear a buffer. This routine essentially fakes an I/O, so we need 3515 * to clear BIO_ERROR and B_INVAL. 3516 * 3517 * Note that while we only theoretically need to clear through b_bcount, 3518 * we go ahead and clear through b_bufsize. 3519 */ 3520 3521void 3522vfs_bio_clrbuf(struct buf *bp) 3523{ 3524 int i, j, mask = 0; 3525 caddr_t sa, ea; 3526 3527 GIANT_REQUIRED; 3528 3529 if ((bp->b_flags & (B_VMIO | B_MALLOC)) == B_VMIO) { 3530 bp->b_flags &= ~B_INVAL; 3531 bp->b_ioflags &= ~BIO_ERROR; 3532 VM_OBJECT_LOCK(bp->b_object); 3533 if( (bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 3534 (bp->b_offset & PAGE_MASK) == 0) { 3535 if (bp->b_pages[0] == bogus_page) 3536 goto unlock; 3537 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 3538 VM_OBJECT_LOCK_ASSERT(bp->b_pages[0]->object, MA_OWNED); 3539 if ((bp->b_pages[0]->valid & mask) == mask) 3540 goto unlock; 3541 if (((bp->b_pages[0]->flags & PG_ZERO) == 0) && 3542 ((bp->b_pages[0]->valid & mask) == 0)) { 3543 bzero(bp->b_data, bp->b_bufsize); 3544 bp->b_pages[0]->valid |= mask; 3545 goto unlock; 3546 } 3547 } 3548 ea = sa = bp->b_data; 3549 for(i=0;i<bp->b_npages;i++,sa=ea) { 3550 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); 3551 ea = (caddr_t)(vm_offset_t)ulmin( 3552 (u_long)(vm_offset_t)ea, 3553 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); 3554 if (bp->b_pages[i] == bogus_page) 3555 continue; 3556 j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; 3557 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 3558 VM_OBJECT_LOCK_ASSERT(bp->b_pages[i]->object, MA_OWNED); 3559 if ((bp->b_pages[i]->valid & mask) == mask) 3560 continue; 3561 if ((bp->b_pages[i]->valid & mask) == 0) { 3562 if ((bp->b_pages[i]->flags & PG_ZERO) == 0) { 3563 bzero(sa, ea - sa); 3564 } 3565 } else { 3566 for (; sa < ea; sa += DEV_BSIZE, j++) { 3567 if (((bp->b_pages[i]->flags & PG_ZERO) == 0) && 3568 (bp->b_pages[i]->valid & (1<<j)) == 0) 3569 bzero(sa, DEV_BSIZE); 3570 } 3571 } 3572 bp->b_pages[i]->valid |= mask; 3573 } 3574unlock: 3575 VM_OBJECT_UNLOCK(bp->b_object); 3576 bp->b_resid = 0; 3577 } else { 3578 clrbuf(bp); 3579 } 3580} 3581 3582/* 3583 * vm_hold_load_pages and vm_hold_free_pages get pages into 3584 * a buffers address space. The pages are anonymous and are 3585 * not associated with a file object. 3586 */ 3587static void 3588vm_hold_load_pages(struct buf * bp, vm_offset_t from, vm_offset_t to) 3589{ 3590 vm_offset_t pg; 3591 vm_page_t p; 3592 int index; 3593 3594 to = round_page(to); 3595 from = round_page(from); 3596 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3597 3598 VM_OBJECT_LOCK(kernel_object); 3599 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3600tryagain: 3601 /* 3602 * note: must allocate system pages since blocking here 3603 * could intefere with paging I/O, no matter which 3604 * process we are. 3605 */ 3606 p = vm_page_alloc(kernel_object, 3607 ((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 3608 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED); 3609 if (!p) { 3610 atomic_add_int(&vm_pageout_deficit, 3611 (to - pg) >> PAGE_SHIFT); 3612 VM_OBJECT_UNLOCK(kernel_object); 3613 VM_WAIT; 3614 VM_OBJECT_LOCK(kernel_object); 3615 goto tryagain; 3616 } 3617 p->valid = VM_PAGE_BITS_ALL; 3618 pmap_qenter(pg, &p, 1); 3619 bp->b_pages[index] = p; 3620 vm_page_lock_queues(); 3621 vm_page_wakeup(p); 3622 vm_page_unlock_queues(); 3623 } 3624 VM_OBJECT_UNLOCK(kernel_object); 3625 bp->b_npages = index; 3626} 3627 3628/* Return pages associated with this buf to the vm system */ 3629static void 3630vm_hold_free_pages(struct buf * bp, vm_offset_t from, vm_offset_t to) 3631{ 3632 vm_offset_t pg; 3633 vm_page_t p; 3634 int index, newnpages; 3635 3636 GIANT_REQUIRED; 3637 3638 from = round_page(from); 3639 to = round_page(to); 3640 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3641 3642 VM_OBJECT_LOCK(kernel_object); 3643 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3644 p = bp->b_pages[index]; 3645 if (p && (index < bp->b_npages)) { 3646 if (p->busy) { 3647 printf( 3648 "vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 3649 (intmax_t)bp->b_blkno, 3650 (intmax_t)bp->b_lblkno); 3651 } 3652 bp->b_pages[index] = NULL; 3653 pmap_qremove(pg, 1); 3654 vm_page_lock_queues(); 3655 vm_page_busy(p); 3656 vm_page_unwire(p, 0); 3657 vm_page_free(p); 3658 vm_page_unlock_queues(); 3659 } 3660 } 3661 VM_OBJECT_UNLOCK(kernel_object); 3662 bp->b_npages = newnpages; 3663} 3664 3665/* 3666 * Map an IO request into kernel virtual address space. 3667 * 3668 * All requests are (re)mapped into kernel VA space. 3669 * Notice that we use b_bufsize for the size of the buffer 3670 * to be mapped. b_bcount might be modified by the driver. 3671 * 3672 * Note that even if the caller determines that the address space should 3673 * be valid, a race or a smaller-file mapped into a larger space may 3674 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 3675 * check the return value. 3676 */ 3677int 3678vmapbuf(struct buf *bp) 3679{ 3680 caddr_t addr, kva; 3681 vm_prot_t prot; 3682 int pidx, i; 3683 struct vm_page *m; 3684 struct pmap *pmap = &curproc->p_vmspace->vm_pmap; 3685 3686 if (bp->b_bufsize < 0) 3687 return (-1); 3688 prot = (bp->b_iocmd == BIO_READ) ? VM_PROT_READ | VM_PROT_WRITE : 3689 VM_PROT_READ; 3690 for (addr = (caddr_t)trunc_page((vm_offset_t)bp->b_data), pidx = 0; 3691 addr < bp->b_data + bp->b_bufsize; 3692 addr += PAGE_SIZE, pidx++) { 3693 /* 3694 * Do the vm_fault if needed; do the copy-on-write thing 3695 * when reading stuff off device into memory. 3696 * 3697 * NOTE! Must use pmap_extract() because addr may be in 3698 * the userland address space, and kextract is only guarenteed 3699 * to work for the kernland address space (see: sparc64 port). 3700 */ 3701retry: 3702 if (vm_fault_quick(addr >= bp->b_data ? addr : bp->b_data, 3703 prot) < 0) { 3704 vm_page_lock_queues(); 3705 for (i = 0; i < pidx; ++i) { 3706 vm_page_unhold(bp->b_pages[i]); 3707 bp->b_pages[i] = NULL; 3708 } 3709 vm_page_unlock_queues(); 3710 return(-1); 3711 } 3712 m = pmap_extract_and_hold(pmap, (vm_offset_t)addr, prot); 3713 if (m == NULL) 3714 goto retry; 3715 bp->b_pages[pidx] = m; 3716 } 3717 if (pidx > btoc(MAXPHYS)) 3718 panic("vmapbuf: mapped more than MAXPHYS"); 3719 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx); 3720 3721 kva = bp->b_saveaddr; 3722 bp->b_npages = pidx; 3723 bp->b_saveaddr = bp->b_data; 3724 bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK); 3725 return(0); 3726} 3727 3728/* 3729 * Free the io map PTEs associated with this IO operation. 3730 * We also invalidate the TLB entries and restore the original b_addr. 3731 */ 3732void 3733vunmapbuf(struct buf *bp) 3734{ 3735 int pidx; 3736 int npages; 3737 3738 npages = bp->b_npages; 3739 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), 3740 npages); 3741 vm_page_lock_queues(); 3742 for (pidx = 0; pidx < npages; pidx++) 3743 vm_page_unhold(bp->b_pages[pidx]); 3744 vm_page_unlock_queues(); 3745 3746 bp->b_data = bp->b_saveaddr; 3747} 3748 3749void 3750bdone(struct buf *bp) 3751{ 3752 mtx_lock(&bdonelock); 3753 bp->b_flags |= B_DONE; 3754 wakeup(bp); 3755 mtx_unlock(&bdonelock); 3756} 3757 3758void 3759bwait(struct buf *bp, u_char pri, const char *wchan) 3760{ 3761 mtx_lock(&bdonelock); 3762 while ((bp->b_flags & B_DONE) == 0) 3763 msleep(bp, &bdonelock, pri, wchan, 0); 3764 mtx_unlock(&bdonelock); 3765} 3766 3767#include "opt_ddb.h" 3768#ifdef DDB 3769#include <ddb/ddb.h> 3770 3771/* DDB command to show buffer data */ 3772DB_SHOW_COMMAND(buffer, db_show_buffer) 3773{ 3774 /* get args */ 3775 struct buf *bp = (struct buf *)addr; 3776 3777 if (!have_addr) { 3778 db_printf("usage: show buffer <addr>\n"); 3779 return; 3780 } 3781 3782 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS); 3783 db_printf( 3784 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 3785 "b_dev = (%d,%d), b_data = %p, b_blkno = %jd\n", 3786 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 3787 major(bp->b_dev), minor(bp->b_dev), bp->b_data, 3788 (intmax_t)bp->b_blkno); 3789 if (bp->b_npages) { 3790 int i; 3791 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 3792 for (i = 0; i < bp->b_npages; i++) { 3793 vm_page_t m; 3794 m = bp->b_pages[i]; 3795 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 3796 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 3797 if ((i + 1) < bp->b_npages) 3798 db_printf(","); 3799 } 3800 db_printf("\n"); 3801 } 3802} 3803#endif /* DDB */ 3804