vfs_bio.c revision 255797
1/*- 2 * Copyright (c) 2004 Poul-Henning Kamp 3 * Copyright (c) 1994,1997 John S. Dyson 4 * Copyright (c) 2013 The FreeBSD Foundation 5 * All rights reserved. 6 * 7 * Portions of this software were developed by Konstantin Belousov 8 * under sponsorship from the FreeBSD Foundation. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32/* 33 * this file contains a new buffer I/O scheme implementing a coherent 34 * VM object and buffer cache scheme. Pains have been taken to make 35 * sure that the performance degradation associated with schemes such 36 * as this is not realized. 37 * 38 * Author: John S. Dyson 39 * Significant help during the development and debugging phases 40 * had been provided by David Greenman, also of the FreeBSD core team. 41 * 42 * see man buf(9) for more info. 43 */ 44 45#include <sys/cdefs.h> 46__FBSDID("$FreeBSD: head/sys/kern/vfs_bio.c 255797 2013-09-22 19:23:48Z kib $"); 47 48#include <sys/param.h> 49#include <sys/systm.h> 50#include <sys/bio.h> 51#include <sys/conf.h> 52#include <sys/buf.h> 53#include <sys/devicestat.h> 54#include <sys/eventhandler.h> 55#include <sys/fail.h> 56#include <sys/limits.h> 57#include <sys/lock.h> 58#include <sys/malloc.h> 59#include <sys/mount.h> 60#include <sys/mutex.h> 61#include <sys/kernel.h> 62#include <sys/kthread.h> 63#include <sys/proc.h> 64#include <sys/resourcevar.h> 65#include <sys/rwlock.h> 66#include <sys/sysctl.h> 67#include <sys/vmem.h> 68#include <sys/vmmeter.h> 69#include <sys/vnode.h> 70#include <geom/geom.h> 71#include <vm/vm.h> 72#include <vm/vm_param.h> 73#include <vm/vm_kern.h> 74#include <vm/vm_pageout.h> 75#include <vm/vm_page.h> 76#include <vm/vm_object.h> 77#include <vm/vm_extern.h> 78#include <vm/vm_map.h> 79#include "opt_compat.h" 80#include "opt_directio.h" 81#include "opt_swap.h" 82 83static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer"); 84 85struct bio_ops bioops; /* I/O operation notification */ 86 87struct buf_ops buf_ops_bio = { 88 .bop_name = "buf_ops_bio", 89 .bop_write = bufwrite, 90 .bop_strategy = bufstrategy, 91 .bop_sync = bufsync, 92 .bop_bdflush = bufbdflush, 93}; 94 95/* 96 * XXX buf is global because kern_shutdown.c and ffs_checkoverlap has 97 * carnal knowledge of buffers. This knowledge should be moved to vfs_bio.c. 98 */ 99struct buf *buf; /* buffer header pool */ 100caddr_t unmapped_buf; 101 102static struct proc *bufdaemonproc; 103 104static int inmem(struct vnode *vp, daddr_t blkno); 105static void vm_hold_free_pages(struct buf *bp, int newbsize); 106static void vm_hold_load_pages(struct buf *bp, vm_offset_t from, 107 vm_offset_t to); 108static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m); 109static void vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, 110 vm_page_t m); 111static void vfs_clean_pages_dirty_buf(struct buf *bp); 112static void vfs_setdirty_locked_object(struct buf *bp); 113static void vfs_vmio_release(struct buf *bp); 114static int vfs_bio_clcheck(struct vnode *vp, int size, 115 daddr_t lblkno, daddr_t blkno); 116static int buf_flush(struct vnode *vp, int); 117static int flushbufqueues(struct vnode *, int, int); 118static void buf_daemon(void); 119static void bremfreel(struct buf *bp); 120static __inline void bd_wakeup(void); 121#if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 122 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 123static int sysctl_bufspace(SYSCTL_HANDLER_ARGS); 124#endif 125 126int vmiodirenable = TRUE; 127SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, 128 "Use the VM system for directory writes"); 129long runningbufspace; 130SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 131 "Amount of presently outstanding async buffer io"); 132static long bufspace; 133#if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 134 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 135SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD, 136 &bufspace, 0, sysctl_bufspace, "L", "Virtual memory used for buffers"); 137#else 138SYSCTL_LONG(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, 139 "Virtual memory used for buffers"); 140#endif 141static long unmapped_bufspace; 142SYSCTL_LONG(_vfs, OID_AUTO, unmapped_bufspace, CTLFLAG_RD, 143 &unmapped_bufspace, 0, 144 "Amount of unmapped buffers, inclusive in the bufspace"); 145static long maxbufspace; 146SYSCTL_LONG(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0, 147 "Maximum allowed value of bufspace (including buf_daemon)"); 148static long bufmallocspace; 149SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 150 "Amount of malloced memory for buffers"); 151static long maxbufmallocspace; 152SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0, 153 "Maximum amount of malloced memory for buffers"); 154static long lobufspace; 155SYSCTL_LONG(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0, 156 "Minimum amount of buffers we want to have"); 157long hibufspace; 158SYSCTL_LONG(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0, 159 "Maximum allowed value of bufspace (excluding buf_daemon)"); 160static int bufreusecnt; 161SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0, 162 "Number of times we have reused a buffer"); 163static int buffreekvacnt; 164SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0, 165 "Number of times we have freed the KVA space from some buffer"); 166static int bufdefragcnt; 167SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0, 168 "Number of times we have had to repeat buffer allocation to defragment"); 169static long lorunningspace; 170SYSCTL_LONG(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0, 171 "Minimum preferred space used for in-progress I/O"); 172static long hirunningspace; 173SYSCTL_LONG(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0, 174 "Maximum amount of space to use for in-progress I/O"); 175int dirtybufferflushes; 176SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes, 177 0, "Number of bdwrite to bawrite conversions to limit dirty buffers"); 178int bdwriteskip; 179SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip, 180 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk"); 181int altbufferflushes; 182SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes, 183 0, "Number of fsync flushes to limit dirty buffers"); 184static int recursiveflushes; 185SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes, 186 0, "Number of flushes skipped due to being recursive"); 187static int numdirtybuffers; 188SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0, 189 "Number of buffers that are dirty (has unwritten changes) at the moment"); 190static int lodirtybuffers; 191SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0, 192 "How many buffers we want to have free before bufdaemon can sleep"); 193static int hidirtybuffers; 194SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0, 195 "When the number of dirty buffers is considered severe"); 196int dirtybufthresh; 197SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh, 198 0, "Number of bdwrite to bawrite conversions to clear dirty buffers"); 199static int numfreebuffers; 200SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, 201 "Number of free buffers"); 202static int lofreebuffers; 203SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0, 204 "XXX Unused"); 205static int hifreebuffers; 206SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0, 207 "XXX Complicatedly unused"); 208static int getnewbufcalls; 209SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0, 210 "Number of calls to getnewbuf"); 211static int getnewbufrestarts; 212SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0, 213 "Number of times getnewbuf has had to restart a buffer aquisition"); 214static int mappingrestarts; 215SYSCTL_INT(_vfs, OID_AUTO, mappingrestarts, CTLFLAG_RW, &mappingrestarts, 0, 216 "Number of times getblk has had to restart a buffer mapping for " 217 "unmapped buffer"); 218static int flushbufqtarget = 100; 219SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0, 220 "Amount of work to do in flushbufqueues when helping bufdaemon"); 221static long notbufdflushes; 222SYSCTL_LONG(_vfs, OID_AUTO, notbufdflushes, CTLFLAG_RD, ¬bufdflushes, 0, 223 "Number of dirty buffer flushes done by the bufdaemon helpers"); 224static long barrierwrites; 225SYSCTL_LONG(_vfs, OID_AUTO, barrierwrites, CTLFLAG_RW, &barrierwrites, 0, 226 "Number of barrier writes"); 227SYSCTL_INT(_vfs, OID_AUTO, unmapped_buf_allowed, CTLFLAG_RD, 228 &unmapped_buf_allowed, 0, 229 "Permit the use of the unmapped i/o"); 230 231/* 232 * Lock for the non-dirty bufqueues 233 */ 234static struct mtx_padalign bqclean; 235 236/* 237 * Lock for the dirty queue. 238 */ 239static struct mtx_padalign bqdirty; 240 241/* 242 * This lock synchronizes access to bd_request. 243 */ 244static struct mtx_padalign bdlock; 245 246/* 247 * This lock protects the runningbufreq and synchronizes runningbufwakeup and 248 * waitrunningbufspace(). 249 */ 250static struct mtx_padalign rbreqlock; 251 252/* 253 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it. 254 */ 255static struct mtx_padalign nblock; 256 257/* 258 * Lock that protects bdirtywait. 259 */ 260static struct mtx_padalign bdirtylock; 261 262/* 263 * Wakeup point for bufdaemon, as well as indicator of whether it is already 264 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it 265 * is idling. 266 */ 267static int bd_request; 268 269/* 270 * Request for the buf daemon to write more buffers than is indicated by 271 * lodirtybuf. This may be necessary to push out excess dependencies or 272 * defragment the address space where a simple count of the number of dirty 273 * buffers is insufficient to characterize the demand for flushing them. 274 */ 275static int bd_speedupreq; 276 277/* 278 * bogus page -- for I/O to/from partially complete buffers 279 * this is a temporary solution to the problem, but it is not 280 * really that bad. it would be better to split the buffer 281 * for input in the case of buffers partially already in memory, 282 * but the code is intricate enough already. 283 */ 284vm_page_t bogus_page; 285 286/* 287 * Synchronization (sleep/wakeup) variable for active buffer space requests. 288 * Set when wait starts, cleared prior to wakeup(). 289 * Used in runningbufwakeup() and waitrunningbufspace(). 290 */ 291static int runningbufreq; 292 293/* 294 * Synchronization (sleep/wakeup) variable for buffer requests. 295 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done 296 * by and/or. 297 * Used in numdirtywakeup(), bufspacewakeup(), bufcountadd(), bwillwrite(), 298 * getnewbuf(), and getblk(). 299 */ 300static int needsbuffer; 301 302/* 303 * Synchronization for bwillwrite() waiters. 304 */ 305static int bdirtywait; 306 307/* 308 * Definitions for the buffer free lists. 309 */ 310#define BUFFER_QUEUES 5 /* number of free buffer queues */ 311 312#define QUEUE_NONE 0 /* on no queue */ 313#define QUEUE_CLEAN 1 /* non-B_DELWRI buffers */ 314#define QUEUE_DIRTY 2 /* B_DELWRI buffers */ 315#define QUEUE_EMPTYKVA 3 /* empty buffer headers w/KVA assignment */ 316#define QUEUE_EMPTY 4 /* empty buffer headers */ 317#define QUEUE_SENTINEL 1024 /* not an queue index, but mark for sentinel */ 318 319/* Queues for free buffers with various properties */ 320static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } }; 321#ifdef INVARIANTS 322static int bq_len[BUFFER_QUEUES]; 323#endif 324 325/* 326 * Single global constant for BUF_WMESG, to avoid getting multiple references. 327 * buf_wmesg is referred from macros. 328 */ 329const char *buf_wmesg = BUF_WMESG; 330 331#define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 332#define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ 333#define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 334 335#if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 336 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 337static int 338sysctl_bufspace(SYSCTL_HANDLER_ARGS) 339{ 340 long lvalue; 341 int ivalue; 342 343 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long)) 344 return (sysctl_handle_long(oidp, arg1, arg2, req)); 345 lvalue = *(long *)arg1; 346 if (lvalue > INT_MAX) 347 /* On overflow, still write out a long to trigger ENOMEM. */ 348 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 349 ivalue = lvalue; 350 return (sysctl_handle_int(oidp, &ivalue, 0, req)); 351} 352#endif 353 354#ifdef DIRECTIO 355extern void ffs_rawread_setup(void); 356#endif /* DIRECTIO */ 357 358/* 359 * bqlock: 360 * 361 * Return the appropriate queue lock based on the index. 362 */ 363static inline struct mtx * 364bqlock(int qindex) 365{ 366 367 if (qindex == QUEUE_DIRTY) 368 return (struct mtx *)(&bqdirty); 369 return (struct mtx *)(&bqclean); 370} 371 372/* 373 * bdirtywakeup: 374 * 375 * Wakeup any bwillwrite() waiters. 376 */ 377static void 378bdirtywakeup(void) 379{ 380 mtx_lock(&bdirtylock); 381 if (bdirtywait) { 382 bdirtywait = 0; 383 wakeup(&bdirtywait); 384 } 385 mtx_unlock(&bdirtylock); 386} 387 388/* 389 * bdirtysub: 390 * 391 * Decrement the numdirtybuffers count by one and wakeup any 392 * threads blocked in bwillwrite(). 393 */ 394static void 395bdirtysub(void) 396{ 397 398 if (atomic_fetchadd_int(&numdirtybuffers, -1) == 399 (lodirtybuffers + hidirtybuffers) / 2) 400 bdirtywakeup(); 401} 402 403/* 404 * bdirtyadd: 405 * 406 * Increment the numdirtybuffers count by one and wakeup the buf 407 * daemon if needed. 408 */ 409static void 410bdirtyadd(void) 411{ 412 413 /* 414 * Only do the wakeup once as we cross the boundary. The 415 * buf daemon will keep running until the condition clears. 416 */ 417 if (atomic_fetchadd_int(&numdirtybuffers, 1) == 418 (lodirtybuffers + hidirtybuffers) / 2) 419 bd_wakeup(); 420} 421 422/* 423 * bufspacewakeup: 424 * 425 * Called when buffer space is potentially available for recovery. 426 * getnewbuf() will block on this flag when it is unable to free 427 * sufficient buffer space. Buffer space becomes recoverable when 428 * bp's get placed back in the queues. 429 */ 430 431static __inline void 432bufspacewakeup(void) 433{ 434 435 /* 436 * If someone is waiting for BUF space, wake them up. Even 437 * though we haven't freed the kva space yet, the waiting 438 * process will be able to now. 439 */ 440 mtx_lock(&nblock); 441 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) { 442 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE; 443 wakeup(&needsbuffer); 444 } 445 mtx_unlock(&nblock); 446} 447 448/* 449 * runningwakeup: 450 * 451 * Wake up processes that are waiting on asynchronous writes to fall 452 * below lorunningspace. 453 */ 454static void 455runningwakeup(void) 456{ 457 458 mtx_lock(&rbreqlock); 459 if (runningbufreq) { 460 runningbufreq = 0; 461 wakeup(&runningbufreq); 462 } 463 mtx_unlock(&rbreqlock); 464} 465 466/* 467 * runningbufwakeup: 468 * 469 * Decrement the outstanding write count according. 470 */ 471void 472runningbufwakeup(struct buf *bp) 473{ 474 long space, bspace; 475 476 bspace = bp->b_runningbufspace; 477 if (bspace == 0) 478 return; 479 space = atomic_fetchadd_long(&runningbufspace, -bspace); 480 KASSERT(space >= bspace, ("runningbufspace underflow %ld %ld", 481 space, bspace)); 482 bp->b_runningbufspace = 0; 483 /* 484 * Only acquire the lock and wakeup on the transition from exceeding 485 * the threshold to falling below it. 486 */ 487 if (space < lorunningspace) 488 return; 489 if (space - bspace > lorunningspace) 490 return; 491 runningwakeup(); 492} 493 494/* 495 * bufcountadd: 496 * 497 * Called when a buffer has been added to one of the free queues to 498 * account for the buffer and to wakeup anyone waiting for free buffers. 499 * This typically occurs when large amounts of metadata are being handled 500 * by the buffer cache ( else buffer space runs out first, usually ). 501 */ 502static __inline void 503bufcountadd(struct buf *bp) 504{ 505 int old; 506 507 KASSERT((bp->b_flags & B_INFREECNT) == 0, 508 ("buf %p already counted as free", bp)); 509 bp->b_flags |= B_INFREECNT; 510 old = atomic_fetchadd_int(&numfreebuffers, 1); 511 KASSERT(old >= 0 && old < nbuf, 512 ("numfreebuffers climbed to %d", old + 1)); 513 mtx_lock(&nblock); 514 if (needsbuffer) { 515 needsbuffer &= ~VFS_BIO_NEED_ANY; 516 if (numfreebuffers >= hifreebuffers) 517 needsbuffer &= ~VFS_BIO_NEED_FREE; 518 wakeup(&needsbuffer); 519 } 520 mtx_unlock(&nblock); 521} 522 523/* 524 * bufcountsub: 525 * 526 * Decrement the numfreebuffers count as needed. 527 */ 528static void 529bufcountsub(struct buf *bp) 530{ 531 int old; 532 533 /* 534 * Fixup numfreebuffers count. If the buffer is invalid or not 535 * delayed-write, the buffer was free and we must decrement 536 * numfreebuffers. 537 */ 538 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { 539 KASSERT((bp->b_flags & B_INFREECNT) != 0, 540 ("buf %p not counted in numfreebuffers", bp)); 541 bp->b_flags &= ~B_INFREECNT; 542 old = atomic_fetchadd_int(&numfreebuffers, -1); 543 KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1)); 544 } 545} 546 547/* 548 * waitrunningbufspace() 549 * 550 * runningbufspace is a measure of the amount of I/O currently 551 * running. This routine is used in async-write situations to 552 * prevent creating huge backups of pending writes to a device. 553 * Only asynchronous writes are governed by this function. 554 * 555 * This does NOT turn an async write into a sync write. It waits 556 * for earlier writes to complete and generally returns before the 557 * caller's write has reached the device. 558 */ 559void 560waitrunningbufspace(void) 561{ 562 563 mtx_lock(&rbreqlock); 564 while (runningbufspace > hirunningspace) { 565 runningbufreq = 1; 566 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 567 } 568 mtx_unlock(&rbreqlock); 569} 570 571 572/* 573 * vfs_buf_test_cache: 574 * 575 * Called when a buffer is extended. This function clears the B_CACHE 576 * bit if the newly extended portion of the buffer does not contain 577 * valid data. 578 */ 579static __inline 580void 581vfs_buf_test_cache(struct buf *bp, 582 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 583 vm_page_t m) 584{ 585 586 VM_OBJECT_ASSERT_LOCKED(m->object); 587 if (bp->b_flags & B_CACHE) { 588 int base = (foff + off) & PAGE_MASK; 589 if (vm_page_is_valid(m, base, size) == 0) 590 bp->b_flags &= ~B_CACHE; 591 } 592} 593 594/* Wake up the buffer daemon if necessary */ 595static __inline void 596bd_wakeup(void) 597{ 598 599 mtx_lock(&bdlock); 600 if (bd_request == 0) { 601 bd_request = 1; 602 wakeup(&bd_request); 603 } 604 mtx_unlock(&bdlock); 605} 606 607/* 608 * bd_speedup - speedup the buffer cache flushing code 609 */ 610void 611bd_speedup(void) 612{ 613 int needwake; 614 615 mtx_lock(&bdlock); 616 needwake = 0; 617 if (bd_speedupreq == 0 || bd_request == 0) 618 needwake = 1; 619 bd_speedupreq = 1; 620 bd_request = 1; 621 if (needwake) 622 wakeup(&bd_request); 623 mtx_unlock(&bdlock); 624} 625 626#ifdef __i386__ 627#define TRANSIENT_DENOM 5 628#else 629#define TRANSIENT_DENOM 10 630#endif 631 632/* 633 * Calculating buffer cache scaling values and reserve space for buffer 634 * headers. This is called during low level kernel initialization and 635 * may be called more then once. We CANNOT write to the memory area 636 * being reserved at this time. 637 */ 638caddr_t 639kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 640{ 641 int tuned_nbuf; 642 long maxbuf, maxbuf_sz, buf_sz, biotmap_sz; 643 644 /* 645 * physmem_est is in pages. Convert it to kilobytes (assumes 646 * PAGE_SIZE is >= 1K) 647 */ 648 physmem_est = physmem_est * (PAGE_SIZE / 1024); 649 650 /* 651 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 652 * For the first 64MB of ram nominally allocate sufficient buffers to 653 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 654 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing 655 * the buffer cache we limit the eventual kva reservation to 656 * maxbcache bytes. 657 * 658 * factor represents the 1/4 x ram conversion. 659 */ 660 if (nbuf == 0) { 661 int factor = 4 * BKVASIZE / 1024; 662 663 nbuf = 50; 664 if (physmem_est > 4096) 665 nbuf += min((physmem_est - 4096) / factor, 666 65536 / factor); 667 if (physmem_est > 65536) 668 nbuf += min((physmem_est - 65536) * 2 / (factor * 5), 669 32 * 1024 * 1024 / (factor * 5)); 670 671 if (maxbcache && nbuf > maxbcache / BKVASIZE) 672 nbuf = maxbcache / BKVASIZE; 673 tuned_nbuf = 1; 674 } else 675 tuned_nbuf = 0; 676 677 /* XXX Avoid unsigned long overflows later on with maxbufspace. */ 678 maxbuf = (LONG_MAX / 3) / BKVASIZE; 679 if (nbuf > maxbuf) { 680 if (!tuned_nbuf) 681 printf("Warning: nbufs lowered from %d to %ld\n", nbuf, 682 maxbuf); 683 nbuf = maxbuf; 684 } 685 686 /* 687 * Ideal allocation size for the transient bio submap if 10% 688 * of the maximal space buffer map. This roughly corresponds 689 * to the amount of the buffer mapped for typical UFS load. 690 * 691 * Clip the buffer map to reserve space for the transient 692 * BIOs, if its extent is bigger than 90% (80% on i386) of the 693 * maximum buffer map extent on the platform. 694 * 695 * The fall-back to the maxbuf in case of maxbcache unset, 696 * allows to not trim the buffer KVA for the architectures 697 * with ample KVA space. 698 */ 699 if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) { 700 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE; 701 buf_sz = (long)nbuf * BKVASIZE; 702 if (buf_sz < maxbuf_sz / TRANSIENT_DENOM * 703 (TRANSIENT_DENOM - 1)) { 704 /* 705 * There is more KVA than memory. Do not 706 * adjust buffer map size, and assign the rest 707 * of maxbuf to transient map. 708 */ 709 biotmap_sz = maxbuf_sz - buf_sz; 710 } else { 711 /* 712 * Buffer map spans all KVA we could afford on 713 * this platform. Give 10% (20% on i386) of 714 * the buffer map to the transient bio map. 715 */ 716 biotmap_sz = buf_sz / TRANSIENT_DENOM; 717 buf_sz -= biotmap_sz; 718 } 719 if (biotmap_sz / INT_MAX > MAXPHYS) 720 bio_transient_maxcnt = INT_MAX; 721 else 722 bio_transient_maxcnt = biotmap_sz / MAXPHYS; 723 /* 724 * Artifically limit to 1024 simultaneous in-flight I/Os 725 * using the transient mapping. 726 */ 727 if (bio_transient_maxcnt > 1024) 728 bio_transient_maxcnt = 1024; 729 if (tuned_nbuf) 730 nbuf = buf_sz / BKVASIZE; 731 } 732 733 /* 734 * swbufs are used as temporary holders for I/O, such as paging I/O. 735 * We have no less then 16 and no more then 256. 736 */ 737 nswbuf = max(min(nbuf/4, 256), 16); 738#ifdef NSWBUF_MIN 739 if (nswbuf < NSWBUF_MIN) 740 nswbuf = NSWBUF_MIN; 741#endif 742#ifdef DIRECTIO 743 ffs_rawread_setup(); 744#endif 745 746 /* 747 * Reserve space for the buffer cache buffers 748 */ 749 swbuf = (void *)v; 750 v = (caddr_t)(swbuf + nswbuf); 751 buf = (void *)v; 752 v = (caddr_t)(buf + nbuf); 753 754 return(v); 755} 756 757/* Initialize the buffer subsystem. Called before use of any buffers. */ 758void 759bufinit(void) 760{ 761 struct buf *bp; 762 int i; 763 764 mtx_init(&bqclean, "bufq clean lock", NULL, MTX_DEF); 765 mtx_init(&bqdirty, "bufq dirty lock", NULL, MTX_DEF); 766 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 767 mtx_init(&nblock, "needsbuffer lock", NULL, MTX_DEF); 768 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 769 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF); 770 771 /* next, make a null set of free lists */ 772 for (i = 0; i < BUFFER_QUEUES; i++) 773 TAILQ_INIT(&bufqueues[i]); 774 775 /* finally, initialize each buffer header and stick on empty q */ 776 for (i = 0; i < nbuf; i++) { 777 bp = &buf[i]; 778 bzero(bp, sizeof *bp); 779 bp->b_flags = B_INVAL | B_INFREECNT; 780 bp->b_rcred = NOCRED; 781 bp->b_wcred = NOCRED; 782 bp->b_qindex = QUEUE_EMPTY; 783 bp->b_xflags = 0; 784 LIST_INIT(&bp->b_dep); 785 BUF_LOCKINIT(bp); 786 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 787#ifdef INVARIANTS 788 bq_len[QUEUE_EMPTY]++; 789#endif 790 } 791 792 /* 793 * maxbufspace is the absolute maximum amount of buffer space we are 794 * allowed to reserve in KVM and in real terms. The absolute maximum 795 * is nominally used by buf_daemon. hibufspace is the nominal maximum 796 * used by most other processes. The differential is required to 797 * ensure that buf_daemon is able to run when other processes might 798 * be blocked waiting for buffer space. 799 * 800 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 801 * this may result in KVM fragmentation which is not handled optimally 802 * by the system. 803 */ 804 maxbufspace = (long)nbuf * BKVASIZE; 805 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 806 lobufspace = hibufspace - MAXBSIZE; 807 808 /* 809 * Note: The 16 MiB upper limit for hirunningspace was chosen 810 * arbitrarily and may need further tuning. It corresponds to 811 * 128 outstanding write IO requests (if IO size is 128 KiB), 812 * which fits with many RAID controllers' tagged queuing limits. 813 * The lower 1 MiB limit is the historical upper limit for 814 * hirunningspace. 815 */ 816 hirunningspace = lmax(lmin(roundup(hibufspace / 64, MAXBSIZE), 817 16 * 1024 * 1024), 1024 * 1024); 818 lorunningspace = roundup((hirunningspace * 2) / 3, MAXBSIZE); 819 820/* 821 * Limit the amount of malloc memory since it is wired permanently into 822 * the kernel space. Even though this is accounted for in the buffer 823 * allocation, we don't want the malloced region to grow uncontrolled. 824 * The malloc scheme improves memory utilization significantly on average 825 * (small) directories. 826 */ 827 maxbufmallocspace = hibufspace / 20; 828 829/* 830 * Reduce the chance of a deadlock occuring by limiting the number 831 * of delayed-write dirty buffers we allow to stack up. 832 */ 833 hidirtybuffers = nbuf / 4 + 20; 834 dirtybufthresh = hidirtybuffers * 9 / 10; 835 numdirtybuffers = 0; 836/* 837 * To support extreme low-memory systems, make sure hidirtybuffers cannot 838 * eat up all available buffer space. This occurs when our minimum cannot 839 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 840 * BKVASIZE'd buffers. 841 */ 842 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 843 hidirtybuffers >>= 1; 844 } 845 lodirtybuffers = hidirtybuffers / 2; 846 847/* 848 * Try to keep the number of free buffers in the specified range, 849 * and give special processes (e.g. like buf_daemon) access to an 850 * emergency reserve. 851 */ 852 lofreebuffers = nbuf / 18 + 5; 853 hifreebuffers = 2 * lofreebuffers; 854 numfreebuffers = nbuf; 855 856 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ | 857 VM_ALLOC_NORMAL | VM_ALLOC_WIRED); 858 unmapped_buf = (caddr_t)kva_alloc(MAXPHYS); 859} 860 861#ifdef INVARIANTS 862static inline void 863vfs_buf_check_mapped(struct buf *bp) 864{ 865 866 KASSERT((bp->b_flags & B_UNMAPPED) == 0, 867 ("mapped buf %p %x", bp, bp->b_flags)); 868 KASSERT(bp->b_kvabase != unmapped_buf, 869 ("mapped buf: b_kvabase was not updated %p", bp)); 870 KASSERT(bp->b_data != unmapped_buf, 871 ("mapped buf: b_data was not updated %p", bp)); 872} 873 874static inline void 875vfs_buf_check_unmapped(struct buf *bp) 876{ 877 878 KASSERT((bp->b_flags & B_UNMAPPED) == B_UNMAPPED, 879 ("unmapped buf %p %x", bp, bp->b_flags)); 880 KASSERT(bp->b_kvabase == unmapped_buf, 881 ("unmapped buf: corrupted b_kvabase %p", bp)); 882 KASSERT(bp->b_data == unmapped_buf, 883 ("unmapped buf: corrupted b_data %p", bp)); 884} 885 886#define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp) 887#define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp) 888#else 889#define BUF_CHECK_MAPPED(bp) do {} while (0) 890#define BUF_CHECK_UNMAPPED(bp) do {} while (0) 891#endif 892 893static void 894bpmap_qenter(struct buf *bp) 895{ 896 897 BUF_CHECK_MAPPED(bp); 898 899 /* 900 * bp->b_data is relative to bp->b_offset, but 901 * bp->b_offset may be offset into the first page. 902 */ 903 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data); 904 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages); 905 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 906 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 907} 908 909/* 910 * bfreekva() - free the kva allocation for a buffer. 911 * 912 * Since this call frees up buffer space, we call bufspacewakeup(). 913 */ 914static void 915bfreekva(struct buf *bp) 916{ 917 918 if (bp->b_kvasize == 0) 919 return; 920 921 atomic_add_int(&buffreekvacnt, 1); 922 atomic_subtract_long(&bufspace, bp->b_kvasize); 923 if ((bp->b_flags & B_UNMAPPED) == 0) { 924 BUF_CHECK_MAPPED(bp); 925 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, 926 bp->b_kvasize); 927 } else { 928 BUF_CHECK_UNMAPPED(bp); 929 if ((bp->b_flags & B_KVAALLOC) != 0) { 930 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvaalloc, 931 bp->b_kvasize); 932 } 933 atomic_subtract_long(&unmapped_bufspace, bp->b_kvasize); 934 bp->b_flags &= ~(B_UNMAPPED | B_KVAALLOC); 935 } 936 bp->b_kvasize = 0; 937 bufspacewakeup(); 938} 939 940/* 941 * binsfree: 942 * 943 * Insert the buffer into the appropriate free list. 944 */ 945static void 946binsfree(struct buf *bp, int qindex) 947{ 948 struct mtx *olock, *nlock; 949 950 BUF_ASSERT_XLOCKED(bp); 951 952 olock = bqlock(bp->b_qindex); 953 nlock = bqlock(qindex); 954 mtx_lock(olock); 955 /* Handle delayed bremfree() processing. */ 956 if (bp->b_flags & B_REMFREE) 957 bremfreel(bp); 958 959 if (bp->b_qindex != QUEUE_NONE) 960 panic("binsfree: free buffer onto another queue???"); 961 962 bp->b_qindex = qindex; 963 if (olock != nlock) { 964 mtx_unlock(olock); 965 mtx_lock(nlock); 966 } 967 if (bp->b_flags & B_AGE) 968 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 969 else 970 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 971#ifdef INVARIANTS 972 bq_len[bp->b_qindex]++; 973#endif 974 mtx_unlock(nlock); 975 976 /* 977 * Something we can maybe free or reuse. 978 */ 979 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 980 bufspacewakeup(); 981 982 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI)) 983 bufcountadd(bp); 984} 985 986/* 987 * bremfree: 988 * 989 * Mark the buffer for removal from the appropriate free list. 990 * 991 */ 992void 993bremfree(struct buf *bp) 994{ 995 996 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 997 KASSERT((bp->b_flags & B_REMFREE) == 0, 998 ("bremfree: buffer %p already marked for delayed removal.", bp)); 999 KASSERT(bp->b_qindex != QUEUE_NONE, 1000 ("bremfree: buffer %p not on a queue.", bp)); 1001 BUF_ASSERT_XLOCKED(bp); 1002 1003 bp->b_flags |= B_REMFREE; 1004 bufcountsub(bp); 1005} 1006 1007/* 1008 * bremfreef: 1009 * 1010 * Force an immediate removal from a free list. Used only in nfs when 1011 * it abuses the b_freelist pointer. 1012 */ 1013void 1014bremfreef(struct buf *bp) 1015{ 1016 struct mtx *qlock; 1017 1018 qlock = bqlock(bp->b_qindex); 1019 mtx_lock(qlock); 1020 bremfreel(bp); 1021 mtx_unlock(qlock); 1022} 1023 1024/* 1025 * bremfreel: 1026 * 1027 * Removes a buffer from the free list, must be called with the 1028 * correct qlock held. 1029 */ 1030static void 1031bremfreel(struct buf *bp) 1032{ 1033 1034 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X", 1035 bp, bp->b_vp, bp->b_flags); 1036 KASSERT(bp->b_qindex != QUEUE_NONE, 1037 ("bremfreel: buffer %p not on a queue.", bp)); 1038 BUF_ASSERT_XLOCKED(bp); 1039 mtx_assert(bqlock(bp->b_qindex), MA_OWNED); 1040 1041 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 1042#ifdef INVARIANTS 1043 KASSERT(bq_len[bp->b_qindex] >= 1, ("queue %d underflow", 1044 bp->b_qindex)); 1045 bq_len[bp->b_qindex]--; 1046#endif 1047 bp->b_qindex = QUEUE_NONE; 1048 /* 1049 * If this was a delayed bremfree() we only need to remove the buffer 1050 * from the queue and return the stats are already done. 1051 */ 1052 if (bp->b_flags & B_REMFREE) { 1053 bp->b_flags &= ~B_REMFREE; 1054 return; 1055 } 1056 bufcountsub(bp); 1057} 1058 1059/* 1060 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 1061 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 1062 * the buffer is valid and we do not have to do anything. 1063 */ 1064void 1065breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, 1066 int cnt, struct ucred * cred) 1067{ 1068 struct buf *rabp; 1069 int i; 1070 1071 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 1072 if (inmem(vp, *rablkno)) 1073 continue; 1074 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 1075 1076 if ((rabp->b_flags & B_CACHE) == 0) { 1077 if (!TD_IS_IDLETHREAD(curthread)) 1078 curthread->td_ru.ru_inblock++; 1079 rabp->b_flags |= B_ASYNC; 1080 rabp->b_flags &= ~B_INVAL; 1081 rabp->b_ioflags &= ~BIO_ERROR; 1082 rabp->b_iocmd = BIO_READ; 1083 if (rabp->b_rcred == NOCRED && cred != NOCRED) 1084 rabp->b_rcred = crhold(cred); 1085 vfs_busy_pages(rabp, 0); 1086 BUF_KERNPROC(rabp); 1087 rabp->b_iooffset = dbtob(rabp->b_blkno); 1088 bstrategy(rabp); 1089 } else { 1090 brelse(rabp); 1091 } 1092 } 1093} 1094 1095/* 1096 * Entry point for bread() and breadn() via #defines in sys/buf.h. 1097 * 1098 * Get a buffer with the specified data. Look in the cache first. We 1099 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 1100 * is set, the buffer is valid and we do not have to do anything, see 1101 * getblk(). Also starts asynchronous I/O on read-ahead blocks. 1102 */ 1103int 1104breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno, 1105 int *rabsize, int cnt, struct ucred *cred, int flags, struct buf **bpp) 1106{ 1107 struct buf *bp; 1108 int rv = 0, readwait = 0; 1109 1110 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 1111 /* 1112 * Can only return NULL if GB_LOCK_NOWAIT flag is specified. 1113 */ 1114 *bpp = bp = getblk(vp, blkno, size, 0, 0, flags); 1115 if (bp == NULL) 1116 return (EBUSY); 1117 1118 /* if not found in cache, do some I/O */ 1119 if ((bp->b_flags & B_CACHE) == 0) { 1120 if (!TD_IS_IDLETHREAD(curthread)) 1121 curthread->td_ru.ru_inblock++; 1122 bp->b_iocmd = BIO_READ; 1123 bp->b_flags &= ~B_INVAL; 1124 bp->b_ioflags &= ~BIO_ERROR; 1125 if (bp->b_rcred == NOCRED && cred != NOCRED) 1126 bp->b_rcred = crhold(cred); 1127 vfs_busy_pages(bp, 0); 1128 bp->b_iooffset = dbtob(bp->b_blkno); 1129 bstrategy(bp); 1130 ++readwait; 1131 } 1132 1133 breada(vp, rablkno, rabsize, cnt, cred); 1134 1135 if (readwait) { 1136 rv = bufwait(bp); 1137 } 1138 return (rv); 1139} 1140 1141/* 1142 * Write, release buffer on completion. (Done by iodone 1143 * if async). Do not bother writing anything if the buffer 1144 * is invalid. 1145 * 1146 * Note that we set B_CACHE here, indicating that buffer is 1147 * fully valid and thus cacheable. This is true even of NFS 1148 * now so we set it generally. This could be set either here 1149 * or in biodone() since the I/O is synchronous. We put it 1150 * here. 1151 */ 1152int 1153bufwrite(struct buf *bp) 1154{ 1155 int oldflags; 1156 struct vnode *vp; 1157 long space; 1158 int vp_md; 1159 1160 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1161 if (bp->b_flags & B_INVAL) { 1162 brelse(bp); 1163 return (0); 1164 } 1165 1166 if (bp->b_flags & B_BARRIER) 1167 barrierwrites++; 1168 1169 oldflags = bp->b_flags; 1170 1171 BUF_ASSERT_HELD(bp); 1172 1173 if (bp->b_pin_count > 0) 1174 bunpin_wait(bp); 1175 1176 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 1177 ("FFS background buffer should not get here %p", bp)); 1178 1179 vp = bp->b_vp; 1180 if (vp) 1181 vp_md = vp->v_vflag & VV_MD; 1182 else 1183 vp_md = 0; 1184 1185 /* 1186 * Mark the buffer clean. Increment the bufobj write count 1187 * before bundirty() call, to prevent other thread from seeing 1188 * empty dirty list and zero counter for writes in progress, 1189 * falsely indicating that the bufobj is clean. 1190 */ 1191 bufobj_wref(bp->b_bufobj); 1192 bundirty(bp); 1193 1194 bp->b_flags &= ~B_DONE; 1195 bp->b_ioflags &= ~BIO_ERROR; 1196 bp->b_flags |= B_CACHE; 1197 bp->b_iocmd = BIO_WRITE; 1198 1199 vfs_busy_pages(bp, 1); 1200 1201 /* 1202 * Normal bwrites pipeline writes 1203 */ 1204 bp->b_runningbufspace = bp->b_bufsize; 1205 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace); 1206 1207 if (!TD_IS_IDLETHREAD(curthread)) 1208 curthread->td_ru.ru_oublock++; 1209 if (oldflags & B_ASYNC) 1210 BUF_KERNPROC(bp); 1211 bp->b_iooffset = dbtob(bp->b_blkno); 1212 bstrategy(bp); 1213 1214 if ((oldflags & B_ASYNC) == 0) { 1215 int rtval = bufwait(bp); 1216 brelse(bp); 1217 return (rtval); 1218 } else if (space > hirunningspace) { 1219 /* 1220 * don't allow the async write to saturate the I/O 1221 * system. We will not deadlock here because 1222 * we are blocking waiting for I/O that is already in-progress 1223 * to complete. We do not block here if it is the update 1224 * or syncer daemon trying to clean up as that can lead 1225 * to deadlock. 1226 */ 1227 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 1228 waitrunningbufspace(); 1229 } 1230 1231 return (0); 1232} 1233 1234void 1235bufbdflush(struct bufobj *bo, struct buf *bp) 1236{ 1237 struct buf *nbp; 1238 1239 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 1240 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 1241 altbufferflushes++; 1242 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 1243 BO_LOCK(bo); 1244 /* 1245 * Try to find a buffer to flush. 1246 */ 1247 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 1248 if ((nbp->b_vflags & BV_BKGRDINPROG) || 1249 BUF_LOCK(nbp, 1250 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 1251 continue; 1252 if (bp == nbp) 1253 panic("bdwrite: found ourselves"); 1254 BO_UNLOCK(bo); 1255 /* Don't countdeps with the bo lock held. */ 1256 if (buf_countdeps(nbp, 0)) { 1257 BO_LOCK(bo); 1258 BUF_UNLOCK(nbp); 1259 continue; 1260 } 1261 if (nbp->b_flags & B_CLUSTEROK) { 1262 vfs_bio_awrite(nbp); 1263 } else { 1264 bremfree(nbp); 1265 bawrite(nbp); 1266 } 1267 dirtybufferflushes++; 1268 break; 1269 } 1270 if (nbp == NULL) 1271 BO_UNLOCK(bo); 1272 } 1273} 1274 1275/* 1276 * Delayed write. (Buffer is marked dirty). Do not bother writing 1277 * anything if the buffer is marked invalid. 1278 * 1279 * Note that since the buffer must be completely valid, we can safely 1280 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 1281 * biodone() in order to prevent getblk from writing the buffer 1282 * out synchronously. 1283 */ 1284void 1285bdwrite(struct buf *bp) 1286{ 1287 struct thread *td = curthread; 1288 struct vnode *vp; 1289 struct bufobj *bo; 1290 1291 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1292 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1293 KASSERT((bp->b_flags & B_BARRIER) == 0, 1294 ("Barrier request in delayed write %p", bp)); 1295 BUF_ASSERT_HELD(bp); 1296 1297 if (bp->b_flags & B_INVAL) { 1298 brelse(bp); 1299 return; 1300 } 1301 1302 /* 1303 * If we have too many dirty buffers, don't create any more. 1304 * If we are wildly over our limit, then force a complete 1305 * cleanup. Otherwise, just keep the situation from getting 1306 * out of control. Note that we have to avoid a recursive 1307 * disaster and not try to clean up after our own cleanup! 1308 */ 1309 vp = bp->b_vp; 1310 bo = bp->b_bufobj; 1311 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 1312 td->td_pflags |= TDP_INBDFLUSH; 1313 BO_BDFLUSH(bo, bp); 1314 td->td_pflags &= ~TDP_INBDFLUSH; 1315 } else 1316 recursiveflushes++; 1317 1318 bdirty(bp); 1319 /* 1320 * Set B_CACHE, indicating that the buffer is fully valid. This is 1321 * true even of NFS now. 1322 */ 1323 bp->b_flags |= B_CACHE; 1324 1325 /* 1326 * This bmap keeps the system from needing to do the bmap later, 1327 * perhaps when the system is attempting to do a sync. Since it 1328 * is likely that the indirect block -- or whatever other datastructure 1329 * that the filesystem needs is still in memory now, it is a good 1330 * thing to do this. Note also, that if the pageout daemon is 1331 * requesting a sync -- there might not be enough memory to do 1332 * the bmap then... So, this is important to do. 1333 */ 1334 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 1335 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 1336 } 1337 1338 /* 1339 * Set the *dirty* buffer range based upon the VM system dirty 1340 * pages. 1341 * 1342 * Mark the buffer pages as clean. We need to do this here to 1343 * satisfy the vnode_pager and the pageout daemon, so that it 1344 * thinks that the pages have been "cleaned". Note that since 1345 * the pages are in a delayed write buffer -- the VFS layer 1346 * "will" see that the pages get written out on the next sync, 1347 * or perhaps the cluster will be completed. 1348 */ 1349 vfs_clean_pages_dirty_buf(bp); 1350 bqrelse(bp); 1351 1352 /* 1353 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 1354 * due to the softdep code. 1355 */ 1356} 1357 1358/* 1359 * bdirty: 1360 * 1361 * Turn buffer into delayed write request. We must clear BIO_READ and 1362 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 1363 * itself to properly update it in the dirty/clean lists. We mark it 1364 * B_DONE to ensure that any asynchronization of the buffer properly 1365 * clears B_DONE ( else a panic will occur later ). 1366 * 1367 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 1368 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 1369 * should only be called if the buffer is known-good. 1370 * 1371 * Since the buffer is not on a queue, we do not update the numfreebuffers 1372 * count. 1373 * 1374 * The buffer must be on QUEUE_NONE. 1375 */ 1376void 1377bdirty(struct buf *bp) 1378{ 1379 1380 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 1381 bp, bp->b_vp, bp->b_flags); 1382 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1383 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1384 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1385 BUF_ASSERT_HELD(bp); 1386 bp->b_flags &= ~(B_RELBUF); 1387 bp->b_iocmd = BIO_WRITE; 1388 1389 if ((bp->b_flags & B_DELWRI) == 0) { 1390 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 1391 reassignbuf(bp); 1392 bdirtyadd(); 1393 } 1394} 1395 1396/* 1397 * bundirty: 1398 * 1399 * Clear B_DELWRI for buffer. 1400 * 1401 * Since the buffer is not on a queue, we do not update the numfreebuffers 1402 * count. 1403 * 1404 * The buffer must be on QUEUE_NONE. 1405 */ 1406 1407void 1408bundirty(struct buf *bp) 1409{ 1410 1411 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1412 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1413 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1414 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1415 BUF_ASSERT_HELD(bp); 1416 1417 if (bp->b_flags & B_DELWRI) { 1418 bp->b_flags &= ~B_DELWRI; 1419 reassignbuf(bp); 1420 bdirtysub(); 1421 } 1422 /* 1423 * Since it is now being written, we can clear its deferred write flag. 1424 */ 1425 bp->b_flags &= ~B_DEFERRED; 1426} 1427 1428/* 1429 * bawrite: 1430 * 1431 * Asynchronous write. Start output on a buffer, but do not wait for 1432 * it to complete. The buffer is released when the output completes. 1433 * 1434 * bwrite() ( or the VOP routine anyway ) is responsible for handling 1435 * B_INVAL buffers. Not us. 1436 */ 1437void 1438bawrite(struct buf *bp) 1439{ 1440 1441 bp->b_flags |= B_ASYNC; 1442 (void) bwrite(bp); 1443} 1444 1445/* 1446 * babarrierwrite: 1447 * 1448 * Asynchronous barrier write. Start output on a buffer, but do not 1449 * wait for it to complete. Place a write barrier after this write so 1450 * that this buffer and all buffers written before it are committed to 1451 * the disk before any buffers written after this write are committed 1452 * to the disk. The buffer is released when the output completes. 1453 */ 1454void 1455babarrierwrite(struct buf *bp) 1456{ 1457 1458 bp->b_flags |= B_ASYNC | B_BARRIER; 1459 (void) bwrite(bp); 1460} 1461 1462/* 1463 * bbarrierwrite: 1464 * 1465 * Synchronous barrier write. Start output on a buffer and wait for 1466 * it to complete. Place a write barrier after this write so that 1467 * this buffer and all buffers written before it are committed to 1468 * the disk before any buffers written after this write are committed 1469 * to the disk. The buffer is released when the output completes. 1470 */ 1471int 1472bbarrierwrite(struct buf *bp) 1473{ 1474 1475 bp->b_flags |= B_BARRIER; 1476 return (bwrite(bp)); 1477} 1478 1479/* 1480 * bwillwrite: 1481 * 1482 * Called prior to the locking of any vnodes when we are expecting to 1483 * write. We do not want to starve the buffer cache with too many 1484 * dirty buffers so we block here. By blocking prior to the locking 1485 * of any vnodes we attempt to avoid the situation where a locked vnode 1486 * prevents the various system daemons from flushing related buffers. 1487 */ 1488void 1489bwillwrite(void) 1490{ 1491 1492 if (numdirtybuffers >= hidirtybuffers) { 1493 mtx_lock(&bdirtylock); 1494 while (numdirtybuffers >= hidirtybuffers) { 1495 bdirtywait = 1; 1496 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4), 1497 "flswai", 0); 1498 } 1499 mtx_unlock(&bdirtylock); 1500 } 1501} 1502 1503/* 1504 * Return true if we have too many dirty buffers. 1505 */ 1506int 1507buf_dirty_count_severe(void) 1508{ 1509 1510 return(numdirtybuffers >= hidirtybuffers); 1511} 1512 1513static __noinline int 1514buf_vm_page_count_severe(void) 1515{ 1516 1517 KFAIL_POINT_CODE(DEBUG_FP, buf_pressure, return 1); 1518 1519 return vm_page_count_severe(); 1520} 1521 1522/* 1523 * brelse: 1524 * 1525 * Release a busy buffer and, if requested, free its resources. The 1526 * buffer will be stashed in the appropriate bufqueue[] allowing it 1527 * to be accessed later as a cache entity or reused for other purposes. 1528 */ 1529void 1530brelse(struct buf *bp) 1531{ 1532 int qindex; 1533 1534 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 1535 bp, bp->b_vp, bp->b_flags); 1536 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1537 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1538 1539 if (BUF_LOCKRECURSED(bp)) { 1540 /* 1541 * Do not process, in particular, do not handle the 1542 * B_INVAL/B_RELBUF and do not release to free list. 1543 */ 1544 BUF_UNLOCK(bp); 1545 return; 1546 } 1547 1548 if (bp->b_flags & B_MANAGED) { 1549 bqrelse(bp); 1550 return; 1551 } 1552 1553 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 1554 bp->b_error == EIO && !(bp->b_flags & B_INVAL)) { 1555 /* 1556 * Failed write, redirty. Must clear BIO_ERROR to prevent 1557 * pages from being scrapped. If the error is anything 1558 * other than an I/O error (EIO), assume that retrying 1559 * is futile. 1560 */ 1561 bp->b_ioflags &= ~BIO_ERROR; 1562 bdirty(bp); 1563 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 1564 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 1565 /* 1566 * Either a failed I/O or we were asked to free or not 1567 * cache the buffer. 1568 */ 1569 bp->b_flags |= B_INVAL; 1570 if (!LIST_EMPTY(&bp->b_dep)) 1571 buf_deallocate(bp); 1572 if (bp->b_flags & B_DELWRI) 1573 bdirtysub(); 1574 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1575 if ((bp->b_flags & B_VMIO) == 0) { 1576 if (bp->b_bufsize) 1577 allocbuf(bp, 0); 1578 if (bp->b_vp) 1579 brelvp(bp); 1580 } 1581 } 1582 1583 /* 1584 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1585 * is called with B_DELWRI set, the underlying pages may wind up 1586 * getting freed causing a previous write (bdwrite()) to get 'lost' 1587 * because pages associated with a B_DELWRI bp are marked clean. 1588 * 1589 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1590 * if B_DELWRI is set. 1591 * 1592 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1593 * on pages to return pages to the VM page queues. 1594 */ 1595 if (bp->b_flags & B_DELWRI) 1596 bp->b_flags &= ~B_RELBUF; 1597 else if (buf_vm_page_count_severe()) { 1598 /* 1599 * BKGRDINPROG can only be set with the buf and bufobj 1600 * locks both held. We tolerate a race to clear it here. 1601 */ 1602 if (!(bp->b_vflags & BV_BKGRDINPROG)) 1603 bp->b_flags |= B_RELBUF; 1604 } 1605 1606 /* 1607 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1608 * constituted, not even NFS buffers now. Two flags effect this. If 1609 * B_INVAL, the struct buf is invalidated but the VM object is kept 1610 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1611 * 1612 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 1613 * invalidated. BIO_ERROR cannot be set for a failed write unless the 1614 * buffer is also B_INVAL because it hits the re-dirtying code above. 1615 * 1616 * Normally we can do this whether a buffer is B_DELWRI or not. If 1617 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1618 * the commit state and we cannot afford to lose the buffer. If the 1619 * buffer has a background write in progress, we need to keep it 1620 * around to prevent it from being reconstituted and starting a second 1621 * background write. 1622 */ 1623 if ((bp->b_flags & B_VMIO) 1624 && !(bp->b_vp->v_mount != NULL && 1625 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 1626 !vn_isdisk(bp->b_vp, NULL) && 1627 (bp->b_flags & B_DELWRI)) 1628 ) { 1629 1630 int i, j, resid; 1631 vm_page_t m; 1632 off_t foff; 1633 vm_pindex_t poff; 1634 vm_object_t obj; 1635 1636 obj = bp->b_bufobj->bo_object; 1637 1638 /* 1639 * Get the base offset and length of the buffer. Note that 1640 * in the VMIO case if the buffer block size is not 1641 * page-aligned then b_data pointer may not be page-aligned. 1642 * But our b_pages[] array *IS* page aligned. 1643 * 1644 * block sizes less then DEV_BSIZE (usually 512) are not 1645 * supported due to the page granularity bits (m->valid, 1646 * m->dirty, etc...). 1647 * 1648 * See man buf(9) for more information 1649 */ 1650 resid = bp->b_bufsize; 1651 foff = bp->b_offset; 1652 for (i = 0; i < bp->b_npages; i++) { 1653 int had_bogus = 0; 1654 1655 m = bp->b_pages[i]; 1656 1657 /* 1658 * If we hit a bogus page, fixup *all* the bogus pages 1659 * now. 1660 */ 1661 if (m == bogus_page) { 1662 poff = OFF_TO_IDX(bp->b_offset); 1663 had_bogus = 1; 1664 1665 VM_OBJECT_RLOCK(obj); 1666 for (j = i; j < bp->b_npages; j++) { 1667 vm_page_t mtmp; 1668 mtmp = bp->b_pages[j]; 1669 if (mtmp == bogus_page) { 1670 mtmp = vm_page_lookup(obj, poff + j); 1671 if (!mtmp) { 1672 panic("brelse: page missing\n"); 1673 } 1674 bp->b_pages[j] = mtmp; 1675 } 1676 } 1677 VM_OBJECT_RUNLOCK(obj); 1678 1679 if ((bp->b_flags & (B_INVAL | B_UNMAPPED)) == 0) { 1680 BUF_CHECK_MAPPED(bp); 1681 pmap_qenter( 1682 trunc_page((vm_offset_t)bp->b_data), 1683 bp->b_pages, bp->b_npages); 1684 } 1685 m = bp->b_pages[i]; 1686 } 1687 if ((bp->b_flags & B_NOCACHE) || 1688 (bp->b_ioflags & BIO_ERROR && 1689 bp->b_iocmd == BIO_READ)) { 1690 int poffset = foff & PAGE_MASK; 1691 int presid = resid > (PAGE_SIZE - poffset) ? 1692 (PAGE_SIZE - poffset) : resid; 1693 1694 KASSERT(presid >= 0, ("brelse: extra page")); 1695 VM_OBJECT_WLOCK(obj); 1696 while (vm_page_xbusied(m)) { 1697 vm_page_lock(m); 1698 VM_OBJECT_WUNLOCK(obj); 1699 vm_page_busy_sleep(m, "mbncsh"); 1700 VM_OBJECT_WLOCK(obj); 1701 } 1702 if (pmap_page_wired_mappings(m) == 0) 1703 vm_page_set_invalid(m, poffset, presid); 1704 VM_OBJECT_WUNLOCK(obj); 1705 if (had_bogus) 1706 printf("avoided corruption bug in bogus_page/brelse code\n"); 1707 } 1708 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1709 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1710 } 1711 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1712 vfs_vmio_release(bp); 1713 1714 } else if (bp->b_flags & B_VMIO) { 1715 1716 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1717 vfs_vmio_release(bp); 1718 } 1719 1720 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) { 1721 if (bp->b_bufsize != 0) 1722 allocbuf(bp, 0); 1723 if (bp->b_vp != NULL) 1724 brelvp(bp); 1725 } 1726 1727 /* 1728 * If the buffer has junk contents signal it and eventually 1729 * clean up B_DELWRI and diassociate the vnode so that gbincore() 1730 * doesn't find it. 1731 */ 1732 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 1733 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 1734 bp->b_flags |= B_INVAL; 1735 if (bp->b_flags & B_INVAL) { 1736 if (bp->b_flags & B_DELWRI) 1737 bundirty(bp); 1738 if (bp->b_vp) 1739 brelvp(bp); 1740 } 1741 1742 /* buffers with no memory */ 1743 if (bp->b_bufsize == 0) { 1744 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1745 if (bp->b_vflags & BV_BKGRDINPROG) 1746 panic("losing buffer 1"); 1747 if (bp->b_kvasize) 1748 qindex = QUEUE_EMPTYKVA; 1749 else 1750 qindex = QUEUE_EMPTY; 1751 bp->b_flags |= B_AGE; 1752 /* buffers with junk contents */ 1753 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 1754 (bp->b_ioflags & BIO_ERROR)) { 1755 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1756 if (bp->b_vflags & BV_BKGRDINPROG) 1757 panic("losing buffer 2"); 1758 qindex = QUEUE_CLEAN; 1759 bp->b_flags |= B_AGE; 1760 /* remaining buffers */ 1761 } else if (bp->b_flags & B_DELWRI) 1762 qindex = QUEUE_DIRTY; 1763 else 1764 qindex = QUEUE_CLEAN; 1765 1766 binsfree(bp, qindex); 1767 1768 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 1769 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1770 panic("brelse: not dirty"); 1771 /* unlock */ 1772 BUF_UNLOCK(bp); 1773} 1774 1775/* 1776 * Release a buffer back to the appropriate queue but do not try to free 1777 * it. The buffer is expected to be used again soon. 1778 * 1779 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1780 * biodone() to requeue an async I/O on completion. It is also used when 1781 * known good buffers need to be requeued but we think we may need the data 1782 * again soon. 1783 * 1784 * XXX we should be able to leave the B_RELBUF hint set on completion. 1785 */ 1786void 1787bqrelse(struct buf *bp) 1788{ 1789 int qindex; 1790 1791 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1792 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1793 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1794 1795 if (BUF_LOCKRECURSED(bp)) { 1796 /* do not release to free list */ 1797 BUF_UNLOCK(bp); 1798 return; 1799 } 1800 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1801 1802 if (bp->b_flags & B_MANAGED) { 1803 if (bp->b_flags & B_REMFREE) 1804 bremfreef(bp); 1805 goto out; 1806 } 1807 1808 /* buffers with stale but valid contents */ 1809 if (bp->b_flags & B_DELWRI) { 1810 qindex = QUEUE_DIRTY; 1811 } else { 1812 if ((bp->b_flags & B_DELWRI) == 0 && 1813 (bp->b_xflags & BX_VNDIRTY)) 1814 panic("bqrelse: not dirty"); 1815 /* 1816 * BKGRDINPROG can only be set with the buf and bufobj 1817 * locks both held. We tolerate a race to clear it here. 1818 */ 1819 if (buf_vm_page_count_severe() && 1820 (bp->b_vflags & BV_BKGRDINPROG) == 0) { 1821 /* 1822 * We are too low on memory, we have to try to free 1823 * the buffer (most importantly: the wired pages 1824 * making up its backing store) *now*. 1825 */ 1826 brelse(bp); 1827 return; 1828 } 1829 qindex = QUEUE_CLEAN; 1830 } 1831 binsfree(bp, qindex); 1832 1833out: 1834 /* unlock */ 1835 BUF_UNLOCK(bp); 1836} 1837 1838/* Give pages used by the bp back to the VM system (where possible) */ 1839static void 1840vfs_vmio_release(struct buf *bp) 1841{ 1842 int i; 1843 vm_page_t m; 1844 1845 if ((bp->b_flags & B_UNMAPPED) == 0) { 1846 BUF_CHECK_MAPPED(bp); 1847 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages); 1848 } else 1849 BUF_CHECK_UNMAPPED(bp); 1850 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 1851 for (i = 0; i < bp->b_npages; i++) { 1852 m = bp->b_pages[i]; 1853 bp->b_pages[i] = NULL; 1854 /* 1855 * In order to keep page LRU ordering consistent, put 1856 * everything on the inactive queue. 1857 */ 1858 vm_page_lock(m); 1859 vm_page_unwire(m, 0); 1860 1861 /* 1862 * Might as well free the page if we can and it has 1863 * no valid data. We also free the page if the 1864 * buffer was used for direct I/O 1865 */ 1866 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid) { 1867 if (m->wire_count == 0 && !vm_page_busied(m)) 1868 vm_page_free(m); 1869 } else if (bp->b_flags & B_DIRECT) 1870 vm_page_try_to_free(m); 1871 else if (buf_vm_page_count_severe()) 1872 vm_page_try_to_cache(m); 1873 vm_page_unlock(m); 1874 } 1875 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 1876 1877 if (bp->b_bufsize) { 1878 bufspacewakeup(); 1879 bp->b_bufsize = 0; 1880 } 1881 bp->b_npages = 0; 1882 bp->b_flags &= ~B_VMIO; 1883 if (bp->b_vp) 1884 brelvp(bp); 1885} 1886 1887/* 1888 * Check to see if a block at a particular lbn is available for a clustered 1889 * write. 1890 */ 1891static int 1892vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 1893{ 1894 struct buf *bpa; 1895 int match; 1896 1897 match = 0; 1898 1899 /* If the buf isn't in core skip it */ 1900 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 1901 return (0); 1902 1903 /* If the buf is busy we don't want to wait for it */ 1904 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1905 return (0); 1906 1907 /* Only cluster with valid clusterable delayed write buffers */ 1908 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 1909 (B_DELWRI | B_CLUSTEROK)) 1910 goto done; 1911 1912 if (bpa->b_bufsize != size) 1913 goto done; 1914 1915 /* 1916 * Check to see if it is in the expected place on disk and that the 1917 * block has been mapped. 1918 */ 1919 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 1920 match = 1; 1921done: 1922 BUF_UNLOCK(bpa); 1923 return (match); 1924} 1925 1926/* 1927 * vfs_bio_awrite: 1928 * 1929 * Implement clustered async writes for clearing out B_DELWRI buffers. 1930 * This is much better then the old way of writing only one buffer at 1931 * a time. Note that we may not be presented with the buffers in the 1932 * correct order, so we search for the cluster in both directions. 1933 */ 1934int 1935vfs_bio_awrite(struct buf *bp) 1936{ 1937 struct bufobj *bo; 1938 int i; 1939 int j; 1940 daddr_t lblkno = bp->b_lblkno; 1941 struct vnode *vp = bp->b_vp; 1942 int ncl; 1943 int nwritten; 1944 int size; 1945 int maxcl; 1946 int gbflags; 1947 1948 bo = &vp->v_bufobj; 1949 gbflags = (bp->b_flags & B_UNMAPPED) != 0 ? GB_UNMAPPED : 0; 1950 /* 1951 * right now we support clustered writing only to regular files. If 1952 * we find a clusterable block we could be in the middle of a cluster 1953 * rather then at the beginning. 1954 */ 1955 if ((vp->v_type == VREG) && 1956 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1957 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1958 1959 size = vp->v_mount->mnt_stat.f_iosize; 1960 maxcl = MAXPHYS / size; 1961 1962 BO_RLOCK(bo); 1963 for (i = 1; i < maxcl; i++) 1964 if (vfs_bio_clcheck(vp, size, lblkno + i, 1965 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 1966 break; 1967 1968 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 1969 if (vfs_bio_clcheck(vp, size, lblkno - j, 1970 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 1971 break; 1972 BO_RUNLOCK(bo); 1973 --j; 1974 ncl = i + j; 1975 /* 1976 * this is a possible cluster write 1977 */ 1978 if (ncl != 1) { 1979 BUF_UNLOCK(bp); 1980 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl, 1981 gbflags); 1982 return (nwritten); 1983 } 1984 } 1985 bremfree(bp); 1986 bp->b_flags |= B_ASYNC; 1987 /* 1988 * default (old) behavior, writing out only one block 1989 * 1990 * XXX returns b_bufsize instead of b_bcount for nwritten? 1991 */ 1992 nwritten = bp->b_bufsize; 1993 (void) bwrite(bp); 1994 1995 return (nwritten); 1996} 1997 1998static void 1999setbufkva(struct buf *bp, vm_offset_t addr, int maxsize, int gbflags) 2000{ 2001 2002 KASSERT((bp->b_flags & (B_UNMAPPED | B_KVAALLOC)) == 0 && 2003 bp->b_kvasize == 0, ("call bfreekva(%p)", bp)); 2004 if ((gbflags & GB_UNMAPPED) == 0) { 2005 bp->b_kvabase = (caddr_t)addr; 2006 } else if ((gbflags & GB_KVAALLOC) != 0) { 2007 KASSERT((gbflags & GB_UNMAPPED) != 0, 2008 ("GB_KVAALLOC without GB_UNMAPPED")); 2009 bp->b_kvaalloc = (caddr_t)addr; 2010 bp->b_flags |= B_UNMAPPED | B_KVAALLOC; 2011 atomic_add_long(&unmapped_bufspace, bp->b_kvasize); 2012 } 2013 bp->b_kvasize = maxsize; 2014} 2015 2016/* 2017 * Allocate the buffer KVA and set b_kvasize. Also set b_kvabase if 2018 * needed. 2019 */ 2020static int 2021allocbufkva(struct buf *bp, int maxsize, int gbflags) 2022{ 2023 vm_offset_t addr; 2024 2025 bfreekva(bp); 2026 addr = 0; 2027 2028 if (vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr)) { 2029 /* 2030 * Buffer map is too fragmented. Request the caller 2031 * to defragment the map. 2032 */ 2033 atomic_add_int(&bufdefragcnt, 1); 2034 return (1); 2035 } 2036 setbufkva(bp, addr, maxsize, gbflags); 2037 atomic_add_long(&bufspace, bp->b_kvasize); 2038 return (0); 2039} 2040 2041/* 2042 * Ask the bufdaemon for help, or act as bufdaemon itself, when a 2043 * locked vnode is supplied. 2044 */ 2045static void 2046getnewbuf_bufd_help(struct vnode *vp, int gbflags, int slpflag, int slptimeo, 2047 int defrag) 2048{ 2049 struct thread *td; 2050 char *waitmsg; 2051 int fl, flags, norunbuf; 2052 2053 mtx_assert(&bqclean, MA_OWNED); 2054 2055 if (defrag) { 2056 flags = VFS_BIO_NEED_BUFSPACE; 2057 waitmsg = "nbufkv"; 2058 } else if (bufspace >= hibufspace) { 2059 waitmsg = "nbufbs"; 2060 flags = VFS_BIO_NEED_BUFSPACE; 2061 } else { 2062 waitmsg = "newbuf"; 2063 flags = VFS_BIO_NEED_ANY; 2064 } 2065 mtx_lock(&nblock); 2066 needsbuffer |= flags; 2067 mtx_unlock(&nblock); 2068 mtx_unlock(&bqclean); 2069 2070 bd_speedup(); /* heeeelp */ 2071 if ((gbflags & GB_NOWAIT_BD) != 0) 2072 return; 2073 2074 td = curthread; 2075 mtx_lock(&nblock); 2076 while (needsbuffer & flags) { 2077 if (vp != NULL && (td->td_pflags & TDP_BUFNEED) == 0) { 2078 mtx_unlock(&nblock); 2079 /* 2080 * getblk() is called with a vnode locked, and 2081 * some majority of the dirty buffers may as 2082 * well belong to the vnode. Flushing the 2083 * buffers there would make a progress that 2084 * cannot be achieved by the buf_daemon, that 2085 * cannot lock the vnode. 2086 */ 2087 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) | 2088 (td->td_pflags & TDP_NORUNNINGBUF); 2089 /* play bufdaemon */ 2090 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF; 2091 fl = buf_flush(vp, flushbufqtarget); 2092 td->td_pflags &= norunbuf; 2093 mtx_lock(&nblock); 2094 if (fl != 0) 2095 continue; 2096 if ((needsbuffer & flags) == 0) 2097 break; 2098 } 2099 if (msleep(&needsbuffer, &nblock, (PRIBIO + 4) | slpflag, 2100 waitmsg, slptimeo)) 2101 break; 2102 } 2103 mtx_unlock(&nblock); 2104} 2105 2106static void 2107getnewbuf_reuse_bp(struct buf *bp, int qindex) 2108{ 2109 2110 CTR6(KTR_BUF, "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d " 2111 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags, 2112 bp->b_kvasize, bp->b_bufsize, qindex); 2113 mtx_assert(&bqclean, MA_NOTOWNED); 2114 2115 /* 2116 * Note: we no longer distinguish between VMIO and non-VMIO 2117 * buffers. 2118 */ 2119 KASSERT((bp->b_flags & B_DELWRI) == 0, 2120 ("delwri buffer %p found in queue %d", bp, qindex)); 2121 2122 if (qindex == QUEUE_CLEAN) { 2123 if (bp->b_flags & B_VMIO) { 2124 bp->b_flags &= ~B_ASYNC; 2125 vfs_vmio_release(bp); 2126 } 2127 if (bp->b_vp != NULL) 2128 brelvp(bp); 2129 } 2130 2131 /* 2132 * Get the rest of the buffer freed up. b_kva* is still valid 2133 * after this operation. 2134 */ 2135 2136 if (bp->b_rcred != NOCRED) { 2137 crfree(bp->b_rcred); 2138 bp->b_rcred = NOCRED; 2139 } 2140 if (bp->b_wcred != NOCRED) { 2141 crfree(bp->b_wcred); 2142 bp->b_wcred = NOCRED; 2143 } 2144 if (!LIST_EMPTY(&bp->b_dep)) 2145 buf_deallocate(bp); 2146 if (bp->b_vflags & BV_BKGRDINPROG) 2147 panic("losing buffer 3"); 2148 KASSERT(bp->b_vp == NULL, ("bp: %p still has vnode %p. qindex: %d", 2149 bp, bp->b_vp, qindex)); 2150 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 2151 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags)); 2152 2153 if (bp->b_bufsize) 2154 allocbuf(bp, 0); 2155 2156 bp->b_flags &= B_UNMAPPED | B_KVAALLOC; 2157 bp->b_ioflags = 0; 2158 bp->b_xflags = 0; 2159 KASSERT((bp->b_flags & B_INFREECNT) == 0, 2160 ("buf %p still counted as free?", bp)); 2161 bp->b_vflags = 0; 2162 bp->b_vp = NULL; 2163 bp->b_blkno = bp->b_lblkno = 0; 2164 bp->b_offset = NOOFFSET; 2165 bp->b_iodone = 0; 2166 bp->b_error = 0; 2167 bp->b_resid = 0; 2168 bp->b_bcount = 0; 2169 bp->b_npages = 0; 2170 bp->b_dirtyoff = bp->b_dirtyend = 0; 2171 bp->b_bufobj = NULL; 2172 bp->b_pin_count = 0; 2173 bp->b_fsprivate1 = NULL; 2174 bp->b_fsprivate2 = NULL; 2175 bp->b_fsprivate3 = NULL; 2176 2177 LIST_INIT(&bp->b_dep); 2178} 2179 2180static int flushingbufs; 2181 2182static struct buf * 2183getnewbuf_scan(int maxsize, int defrag, int unmapped, int metadata) 2184{ 2185 struct buf *bp, *nbp; 2186 int nqindex, qindex, pass; 2187 2188 KASSERT(!unmapped || !defrag, ("both unmapped and defrag")); 2189 2190 pass = 1; 2191restart: 2192 atomic_add_int(&getnewbufrestarts, 1); 2193 2194 /* 2195 * Setup for scan. If we do not have enough free buffers, 2196 * we setup a degenerate case that immediately fails. Note 2197 * that if we are specially marked process, we are allowed to 2198 * dip into our reserves. 2199 * 2200 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 2201 * for the allocation of the mapped buffer. For unmapped, the 2202 * easiest is to start with EMPTY outright. 2203 * 2204 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 2205 * However, there are a number of cases (defragging, reusing, ...) 2206 * where we cannot backup. 2207 */ 2208 nbp = NULL; 2209 mtx_lock(&bqclean); 2210 if (!defrag && unmapped) { 2211 nqindex = QUEUE_EMPTY; 2212 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 2213 } 2214 if (nbp == NULL) { 2215 nqindex = QUEUE_EMPTYKVA; 2216 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 2217 } 2218 2219 /* 2220 * If no EMPTYKVA buffers and we are either defragging or 2221 * reusing, locate a CLEAN buffer to free or reuse. If 2222 * bufspace useage is low skip this step so we can allocate a 2223 * new buffer. 2224 */ 2225 if (nbp == NULL && (defrag || bufspace >= lobufspace)) { 2226 nqindex = QUEUE_CLEAN; 2227 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2228 } 2229 2230 /* 2231 * If we could not find or were not allowed to reuse a CLEAN 2232 * buffer, check to see if it is ok to use an EMPTY buffer. 2233 * We can only use an EMPTY buffer if allocating its KVA would 2234 * not otherwise run us out of buffer space. No KVA is needed 2235 * for the unmapped allocation. 2236 */ 2237 if (nbp == NULL && defrag == 0 && (bufspace + maxsize < hibufspace || 2238 metadata)) { 2239 nqindex = QUEUE_EMPTY; 2240 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 2241 } 2242 2243 /* 2244 * All available buffers might be clean, retry ignoring the 2245 * lobufspace as the last resort. 2246 */ 2247 if (nbp == NULL && !TAILQ_EMPTY(&bufqueues[QUEUE_CLEAN])) { 2248 nqindex = QUEUE_CLEAN; 2249 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2250 } 2251 2252 /* 2253 * Run scan, possibly freeing data and/or kva mappings on the fly 2254 * depending. 2255 */ 2256 while ((bp = nbp) != NULL) { 2257 qindex = nqindex; 2258 2259 /* 2260 * Calculate next bp (we can only use it if we do not 2261 * block or do other fancy things). 2262 */ 2263 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 2264 switch (qindex) { 2265 case QUEUE_EMPTY: 2266 nqindex = QUEUE_EMPTYKVA; 2267 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 2268 if (nbp != NULL) 2269 break; 2270 /* FALLTHROUGH */ 2271 case QUEUE_EMPTYKVA: 2272 nqindex = QUEUE_CLEAN; 2273 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2274 if (nbp != NULL) 2275 break; 2276 /* FALLTHROUGH */ 2277 case QUEUE_CLEAN: 2278 if (metadata && pass == 1) { 2279 pass = 2; 2280 nqindex = QUEUE_EMPTY; 2281 nbp = TAILQ_FIRST( 2282 &bufqueues[QUEUE_EMPTY]); 2283 } 2284 /* 2285 * nbp is NULL. 2286 */ 2287 break; 2288 } 2289 } 2290 /* 2291 * If we are defragging then we need a buffer with 2292 * b_kvasize != 0. XXX this situation should no longer 2293 * occur, if defrag is non-zero the buffer's b_kvasize 2294 * should also be non-zero at this point. XXX 2295 */ 2296 if (defrag && bp->b_kvasize == 0) { 2297 printf("Warning: defrag empty buffer %p\n", bp); 2298 continue; 2299 } 2300 2301 /* 2302 * Start freeing the bp. This is somewhat involved. nbp 2303 * remains valid only for QUEUE_EMPTY[KVA] bp's. 2304 */ 2305 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2306 continue; 2307 /* 2308 * BKGRDINPROG can only be set with the buf and bufobj 2309 * locks both held. We tolerate a race to clear it here. 2310 */ 2311 if (bp->b_vflags & BV_BKGRDINPROG) { 2312 BUF_UNLOCK(bp); 2313 continue; 2314 } 2315 2316 KASSERT(bp->b_qindex == qindex, 2317 ("getnewbuf: inconsistent queue %d bp %p", qindex, bp)); 2318 2319 bremfreel(bp); 2320 mtx_unlock(&bqclean); 2321 /* 2322 * NOTE: nbp is now entirely invalid. We can only restart 2323 * the scan from this point on. 2324 */ 2325 2326 getnewbuf_reuse_bp(bp, qindex); 2327 mtx_assert(&bqclean, MA_NOTOWNED); 2328 2329 /* 2330 * If we are defragging then free the buffer. 2331 */ 2332 if (defrag) { 2333 bp->b_flags |= B_INVAL; 2334 bfreekva(bp); 2335 brelse(bp); 2336 defrag = 0; 2337 goto restart; 2338 } 2339 2340 /* 2341 * Notify any waiters for the buffer lock about 2342 * identity change by freeing the buffer. 2343 */ 2344 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp)) { 2345 bp->b_flags |= B_INVAL; 2346 bfreekva(bp); 2347 brelse(bp); 2348 goto restart; 2349 } 2350 2351 if (metadata) 2352 break; 2353 2354 /* 2355 * If we are overcomitted then recover the buffer and its 2356 * KVM space. This occurs in rare situations when multiple 2357 * processes are blocked in getnewbuf() or allocbuf(). 2358 */ 2359 if (bufspace >= hibufspace) 2360 flushingbufs = 1; 2361 if (flushingbufs && bp->b_kvasize != 0) { 2362 bp->b_flags |= B_INVAL; 2363 bfreekva(bp); 2364 brelse(bp); 2365 goto restart; 2366 } 2367 if (bufspace < lobufspace) 2368 flushingbufs = 0; 2369 break; 2370 } 2371 return (bp); 2372} 2373 2374/* 2375 * getnewbuf: 2376 * 2377 * Find and initialize a new buffer header, freeing up existing buffers 2378 * in the bufqueues as necessary. The new buffer is returned locked. 2379 * 2380 * Important: B_INVAL is not set. If the caller wishes to throw the 2381 * buffer away, the caller must set B_INVAL prior to calling brelse(). 2382 * 2383 * We block if: 2384 * We have insufficient buffer headers 2385 * We have insufficient buffer space 2386 * buffer_arena is too fragmented ( space reservation fails ) 2387 * If we have to flush dirty buffers ( but we try to avoid this ) 2388 */ 2389static struct buf * 2390getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int size, int maxsize, 2391 int gbflags) 2392{ 2393 struct buf *bp; 2394 int defrag, metadata; 2395 2396 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 2397 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 2398 if (!unmapped_buf_allowed) 2399 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC); 2400 2401 defrag = 0; 2402 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 || 2403 vp->v_type == VCHR) 2404 metadata = 1; 2405 else 2406 metadata = 0; 2407 /* 2408 * We can't afford to block since we might be holding a vnode lock, 2409 * which may prevent system daemons from running. We deal with 2410 * low-memory situations by proactively returning memory and running 2411 * async I/O rather then sync I/O. 2412 */ 2413 atomic_add_int(&getnewbufcalls, 1); 2414 atomic_subtract_int(&getnewbufrestarts, 1); 2415restart: 2416 bp = getnewbuf_scan(maxsize, defrag, (gbflags & (GB_UNMAPPED | 2417 GB_KVAALLOC)) == GB_UNMAPPED, metadata); 2418 if (bp != NULL) 2419 defrag = 0; 2420 2421 /* 2422 * If we exhausted our list, sleep as appropriate. We may have to 2423 * wakeup various daemons and write out some dirty buffers. 2424 * 2425 * Generally we are sleeping due to insufficient buffer space. 2426 */ 2427 if (bp == NULL) { 2428 mtx_assert(&bqclean, MA_OWNED); 2429 getnewbuf_bufd_help(vp, gbflags, slpflag, slptimeo, defrag); 2430 mtx_assert(&bqclean, MA_NOTOWNED); 2431 } else if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == GB_UNMAPPED) { 2432 mtx_assert(&bqclean, MA_NOTOWNED); 2433 2434 bfreekva(bp); 2435 bp->b_flags |= B_UNMAPPED; 2436 bp->b_kvabase = bp->b_data = unmapped_buf; 2437 bp->b_kvasize = maxsize; 2438 atomic_add_long(&bufspace, bp->b_kvasize); 2439 atomic_add_long(&unmapped_bufspace, bp->b_kvasize); 2440 atomic_add_int(&bufreusecnt, 1); 2441 } else { 2442 mtx_assert(&bqclean, MA_NOTOWNED); 2443 2444 /* 2445 * We finally have a valid bp. We aren't quite out of the 2446 * woods, we still have to reserve kva space. In order 2447 * to keep fragmentation sane we only allocate kva in 2448 * BKVASIZE chunks. 2449 */ 2450 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2451 2452 if (maxsize != bp->b_kvasize || (bp->b_flags & (B_UNMAPPED | 2453 B_KVAALLOC)) == B_UNMAPPED) { 2454 if (allocbufkva(bp, maxsize, gbflags)) { 2455 defrag = 1; 2456 bp->b_flags |= B_INVAL; 2457 brelse(bp); 2458 goto restart; 2459 } 2460 atomic_add_int(&bufreusecnt, 1); 2461 } else if ((bp->b_flags & B_KVAALLOC) != 0 && 2462 (gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == 0) { 2463 /* 2464 * If the reused buffer has KVA allocated, 2465 * reassign b_kvaalloc to b_kvabase. 2466 */ 2467 bp->b_kvabase = bp->b_kvaalloc; 2468 bp->b_flags &= ~B_KVAALLOC; 2469 atomic_subtract_long(&unmapped_bufspace, 2470 bp->b_kvasize); 2471 atomic_add_int(&bufreusecnt, 1); 2472 } else if ((bp->b_flags & (B_UNMAPPED | B_KVAALLOC)) == 0 && 2473 (gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == (GB_UNMAPPED | 2474 GB_KVAALLOC)) { 2475 /* 2476 * The case of reused buffer already have KVA 2477 * mapped, but the request is for unmapped 2478 * buffer with KVA allocated. 2479 */ 2480 bp->b_kvaalloc = bp->b_kvabase; 2481 bp->b_data = bp->b_kvabase = unmapped_buf; 2482 bp->b_flags |= B_UNMAPPED | B_KVAALLOC; 2483 atomic_add_long(&unmapped_bufspace, 2484 bp->b_kvasize); 2485 atomic_add_int(&bufreusecnt, 1); 2486 } 2487 if ((gbflags & GB_UNMAPPED) == 0) { 2488 bp->b_saveaddr = bp->b_kvabase; 2489 bp->b_data = bp->b_saveaddr; 2490 bp->b_flags &= ~B_UNMAPPED; 2491 BUF_CHECK_MAPPED(bp); 2492 } 2493 } 2494 return (bp); 2495} 2496 2497/* 2498 * buf_daemon: 2499 * 2500 * buffer flushing daemon. Buffers are normally flushed by the 2501 * update daemon but if it cannot keep up this process starts to 2502 * take the load in an attempt to prevent getnewbuf() from blocking. 2503 */ 2504 2505static struct kproc_desc buf_kp = { 2506 "bufdaemon", 2507 buf_daemon, 2508 &bufdaemonproc 2509}; 2510SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 2511 2512static int 2513buf_flush(struct vnode *vp, int target) 2514{ 2515 int flushed; 2516 2517 flushed = flushbufqueues(vp, target, 0); 2518 if (flushed == 0) { 2519 /* 2520 * Could not find any buffers without rollback 2521 * dependencies, so just write the first one 2522 * in the hopes of eventually making progress. 2523 */ 2524 if (vp != NULL && target > 2) 2525 target /= 2; 2526 flushbufqueues(vp, target, 1); 2527 } 2528 return (flushed); 2529} 2530 2531static void 2532buf_daemon() 2533{ 2534 int lodirty; 2535 2536 /* 2537 * This process needs to be suspended prior to shutdown sync. 2538 */ 2539 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2540 SHUTDOWN_PRI_LAST); 2541 2542 /* 2543 * This process is allowed to take the buffer cache to the limit 2544 */ 2545 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 2546 mtx_lock(&bdlock); 2547 for (;;) { 2548 bd_request = 0; 2549 mtx_unlock(&bdlock); 2550 2551 kproc_suspend_check(bufdaemonproc); 2552 lodirty = lodirtybuffers; 2553 if (bd_speedupreq) { 2554 lodirty = numdirtybuffers / 2; 2555 bd_speedupreq = 0; 2556 } 2557 /* 2558 * Do the flush. Limit the amount of in-transit I/O we 2559 * allow to build up, otherwise we would completely saturate 2560 * the I/O system. 2561 */ 2562 while (numdirtybuffers > lodirty) { 2563 if (buf_flush(NULL, numdirtybuffers - lodirty) == 0) 2564 break; 2565 kern_yield(PRI_USER); 2566 } 2567 2568 /* 2569 * Only clear bd_request if we have reached our low water 2570 * mark. The buf_daemon normally waits 1 second and 2571 * then incrementally flushes any dirty buffers that have 2572 * built up, within reason. 2573 * 2574 * If we were unable to hit our low water mark and couldn't 2575 * find any flushable buffers, we sleep for a short period 2576 * to avoid endless loops on unlockable buffers. 2577 */ 2578 mtx_lock(&bdlock); 2579 if (numdirtybuffers <= lodirtybuffers) { 2580 /* 2581 * We reached our low water mark, reset the 2582 * request and sleep until we are needed again. 2583 * The sleep is just so the suspend code works. 2584 */ 2585 bd_request = 0; 2586 /* 2587 * Do an extra wakeup in case dirty threshold 2588 * changed via sysctl and the explicit transition 2589 * out of shortfall was missed. 2590 */ 2591 bdirtywakeup(); 2592 if (runningbufspace <= lorunningspace) 2593 runningwakeup(); 2594 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 2595 } else { 2596 /* 2597 * We couldn't find any flushable dirty buffers but 2598 * still have too many dirty buffers, we 2599 * have to sleep and try again. (rare) 2600 */ 2601 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 2602 } 2603 } 2604} 2605 2606/* 2607 * flushbufqueues: 2608 * 2609 * Try to flush a buffer in the dirty queue. We must be careful to 2610 * free up B_INVAL buffers instead of write them, which NFS is 2611 * particularly sensitive to. 2612 */ 2613static int flushwithdeps = 0; 2614SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 2615 0, "Number of buffers flushed with dependecies that require rollbacks"); 2616 2617static int 2618flushbufqueues(struct vnode *lvp, int target, int flushdeps) 2619{ 2620 struct buf *sentinel; 2621 struct vnode *vp; 2622 struct mount *mp; 2623 struct buf *bp; 2624 int hasdeps; 2625 int flushed; 2626 int queue; 2627 int error; 2628 bool unlock; 2629 2630 flushed = 0; 2631 queue = QUEUE_DIRTY; 2632 bp = NULL; 2633 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 2634 sentinel->b_qindex = QUEUE_SENTINEL; 2635 mtx_lock(&bqdirty); 2636 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist); 2637 while (flushed != target) { 2638 bp = TAILQ_NEXT(sentinel, b_freelist); 2639 if (bp != NULL) { 2640 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2641 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel, 2642 b_freelist); 2643 } else 2644 break; 2645 /* 2646 * Skip sentinels inserted by other invocations of the 2647 * flushbufqueues(), taking care to not reorder them. 2648 */ 2649 if (bp->b_qindex == QUEUE_SENTINEL) 2650 continue; 2651 /* 2652 * Only flush the buffers that belong to the 2653 * vnode locked by the curthread. 2654 */ 2655 if (lvp != NULL && bp->b_vp != lvp) 2656 continue; 2657 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2658 continue; 2659 if (bp->b_pin_count > 0) { 2660 BUF_UNLOCK(bp); 2661 continue; 2662 } 2663 /* 2664 * BKGRDINPROG can only be set with the buf and bufobj 2665 * locks both held. We tolerate a race to clear it here. 2666 */ 2667 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 2668 (bp->b_flags & B_DELWRI) == 0) { 2669 BUF_UNLOCK(bp); 2670 continue; 2671 } 2672 if (bp->b_flags & B_INVAL) { 2673 bremfreel(bp); 2674 mtx_unlock(&bqdirty); 2675 brelse(bp); 2676 flushed++; 2677 mtx_lock(&bqdirty); 2678 continue; 2679 } 2680 2681 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 2682 if (flushdeps == 0) { 2683 BUF_UNLOCK(bp); 2684 continue; 2685 } 2686 hasdeps = 1; 2687 } else 2688 hasdeps = 0; 2689 /* 2690 * We must hold the lock on a vnode before writing 2691 * one of its buffers. Otherwise we may confuse, or 2692 * in the case of a snapshot vnode, deadlock the 2693 * system. 2694 * 2695 * The lock order here is the reverse of the normal 2696 * of vnode followed by buf lock. This is ok because 2697 * the NOWAIT will prevent deadlock. 2698 */ 2699 vp = bp->b_vp; 2700 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 2701 BUF_UNLOCK(bp); 2702 continue; 2703 } 2704 if (lvp == NULL) { 2705 unlock = true; 2706 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT); 2707 } else { 2708 ASSERT_VOP_LOCKED(vp, "getbuf"); 2709 unlock = false; 2710 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 : 2711 vn_lock(vp, LK_UPGRADE | LK_NOWAIT); 2712 } 2713 if (error == 0) { 2714 mtx_unlock(&bqdirty); 2715 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 2716 bp, bp->b_vp, bp->b_flags); 2717 if (curproc == bufdaemonproc) 2718 vfs_bio_awrite(bp); 2719 else { 2720 bremfree(bp); 2721 bwrite(bp); 2722 notbufdflushes++; 2723 } 2724 vn_finished_write(mp); 2725 if (unlock) 2726 VOP_UNLOCK(vp, 0); 2727 flushwithdeps += hasdeps; 2728 flushed++; 2729 2730 /* 2731 * Sleeping on runningbufspace while holding 2732 * vnode lock leads to deadlock. 2733 */ 2734 if (curproc == bufdaemonproc && 2735 runningbufspace > hirunningspace) 2736 waitrunningbufspace(); 2737 mtx_lock(&bqdirty); 2738 continue; 2739 } 2740 vn_finished_write(mp); 2741 BUF_UNLOCK(bp); 2742 } 2743 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2744 mtx_unlock(&bqdirty); 2745 free(sentinel, M_TEMP); 2746 return (flushed); 2747} 2748 2749/* 2750 * Check to see if a block is currently memory resident. 2751 */ 2752struct buf * 2753incore(struct bufobj *bo, daddr_t blkno) 2754{ 2755 struct buf *bp; 2756 2757 BO_RLOCK(bo); 2758 bp = gbincore(bo, blkno); 2759 BO_RUNLOCK(bo); 2760 return (bp); 2761} 2762 2763/* 2764 * Returns true if no I/O is needed to access the 2765 * associated VM object. This is like incore except 2766 * it also hunts around in the VM system for the data. 2767 */ 2768 2769static int 2770inmem(struct vnode * vp, daddr_t blkno) 2771{ 2772 vm_object_t obj; 2773 vm_offset_t toff, tinc, size; 2774 vm_page_t m; 2775 vm_ooffset_t off; 2776 2777 ASSERT_VOP_LOCKED(vp, "inmem"); 2778 2779 if (incore(&vp->v_bufobj, blkno)) 2780 return 1; 2781 if (vp->v_mount == NULL) 2782 return 0; 2783 obj = vp->v_object; 2784 if (obj == NULL) 2785 return (0); 2786 2787 size = PAGE_SIZE; 2788 if (size > vp->v_mount->mnt_stat.f_iosize) 2789 size = vp->v_mount->mnt_stat.f_iosize; 2790 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2791 2792 VM_OBJECT_RLOCK(obj); 2793 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2794 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2795 if (!m) 2796 goto notinmem; 2797 tinc = size; 2798 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2799 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2800 if (vm_page_is_valid(m, 2801 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2802 goto notinmem; 2803 } 2804 VM_OBJECT_RUNLOCK(obj); 2805 return 1; 2806 2807notinmem: 2808 VM_OBJECT_RUNLOCK(obj); 2809 return (0); 2810} 2811 2812/* 2813 * Set the dirty range for a buffer based on the status of the dirty 2814 * bits in the pages comprising the buffer. The range is limited 2815 * to the size of the buffer. 2816 * 2817 * Tell the VM system that the pages associated with this buffer 2818 * are clean. This is used for delayed writes where the data is 2819 * going to go to disk eventually without additional VM intevention. 2820 * 2821 * Note that while we only really need to clean through to b_bcount, we 2822 * just go ahead and clean through to b_bufsize. 2823 */ 2824static void 2825vfs_clean_pages_dirty_buf(struct buf *bp) 2826{ 2827 vm_ooffset_t foff, noff, eoff; 2828 vm_page_t m; 2829 int i; 2830 2831 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 2832 return; 2833 2834 foff = bp->b_offset; 2835 KASSERT(bp->b_offset != NOOFFSET, 2836 ("vfs_clean_pages_dirty_buf: no buffer offset")); 2837 2838 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 2839 vfs_drain_busy_pages(bp); 2840 vfs_setdirty_locked_object(bp); 2841 for (i = 0; i < bp->b_npages; i++) { 2842 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2843 eoff = noff; 2844 if (eoff > bp->b_offset + bp->b_bufsize) 2845 eoff = bp->b_offset + bp->b_bufsize; 2846 m = bp->b_pages[i]; 2847 vfs_page_set_validclean(bp, foff, m); 2848 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 2849 foff = noff; 2850 } 2851 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 2852} 2853 2854static void 2855vfs_setdirty_locked_object(struct buf *bp) 2856{ 2857 vm_object_t object; 2858 int i; 2859 2860 object = bp->b_bufobj->bo_object; 2861 VM_OBJECT_ASSERT_WLOCKED(object); 2862 2863 /* 2864 * We qualify the scan for modified pages on whether the 2865 * object has been flushed yet. 2866 */ 2867 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) { 2868 vm_offset_t boffset; 2869 vm_offset_t eoffset; 2870 2871 /* 2872 * test the pages to see if they have been modified directly 2873 * by users through the VM system. 2874 */ 2875 for (i = 0; i < bp->b_npages; i++) 2876 vm_page_test_dirty(bp->b_pages[i]); 2877 2878 /* 2879 * Calculate the encompassing dirty range, boffset and eoffset, 2880 * (eoffset - boffset) bytes. 2881 */ 2882 2883 for (i = 0; i < bp->b_npages; i++) { 2884 if (bp->b_pages[i]->dirty) 2885 break; 2886 } 2887 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2888 2889 for (i = bp->b_npages - 1; i >= 0; --i) { 2890 if (bp->b_pages[i]->dirty) { 2891 break; 2892 } 2893 } 2894 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2895 2896 /* 2897 * Fit it to the buffer. 2898 */ 2899 2900 if (eoffset > bp->b_bcount) 2901 eoffset = bp->b_bcount; 2902 2903 /* 2904 * If we have a good dirty range, merge with the existing 2905 * dirty range. 2906 */ 2907 2908 if (boffset < eoffset) { 2909 if (bp->b_dirtyoff > boffset) 2910 bp->b_dirtyoff = boffset; 2911 if (bp->b_dirtyend < eoffset) 2912 bp->b_dirtyend = eoffset; 2913 } 2914 } 2915} 2916 2917/* 2918 * Allocate the KVA mapping for an existing buffer. It handles the 2919 * cases of both B_UNMAPPED buffer, and buffer with the preallocated 2920 * KVA which is not mapped (B_KVAALLOC). 2921 */ 2922static void 2923bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags) 2924{ 2925 struct buf *scratch_bp; 2926 int bsize, maxsize, need_mapping, need_kva; 2927 off_t offset; 2928 2929 need_mapping = (bp->b_flags & B_UNMAPPED) != 0 && 2930 (gbflags & GB_UNMAPPED) == 0; 2931 need_kva = (bp->b_flags & (B_KVAALLOC | B_UNMAPPED)) == B_UNMAPPED && 2932 (gbflags & GB_KVAALLOC) != 0; 2933 if (!need_mapping && !need_kva) 2934 return; 2935 2936 BUF_CHECK_UNMAPPED(bp); 2937 2938 if (need_mapping && (bp->b_flags & B_KVAALLOC) != 0) { 2939 /* 2940 * Buffer is not mapped, but the KVA was already 2941 * reserved at the time of the instantiation. Use the 2942 * allocated space. 2943 */ 2944 bp->b_flags &= ~B_KVAALLOC; 2945 KASSERT(bp->b_kvaalloc != 0, ("kvaalloc == 0")); 2946 bp->b_kvabase = bp->b_kvaalloc; 2947 atomic_subtract_long(&unmapped_bufspace, bp->b_kvasize); 2948 goto has_addr; 2949 } 2950 2951 /* 2952 * Calculate the amount of the address space we would reserve 2953 * if the buffer was mapped. 2954 */ 2955 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize; 2956 offset = blkno * bsize; 2957 maxsize = size + (offset & PAGE_MASK); 2958 maxsize = imax(maxsize, bsize); 2959 2960mapping_loop: 2961 if (allocbufkva(bp, maxsize, gbflags)) { 2962 /* 2963 * Request defragmentation. getnewbuf() returns us the 2964 * allocated space by the scratch buffer KVA. 2965 */ 2966 scratch_bp = getnewbuf(bp->b_vp, 0, 0, size, maxsize, gbflags | 2967 (GB_UNMAPPED | GB_KVAALLOC)); 2968 if (scratch_bp == NULL) { 2969 if ((gbflags & GB_NOWAIT_BD) != 0) { 2970 /* 2971 * XXXKIB: defragmentation cannot 2972 * succeed, not sure what else to do. 2973 */ 2974 panic("GB_NOWAIT_BD and B_UNMAPPED %p", bp); 2975 } 2976 atomic_add_int(&mappingrestarts, 1); 2977 goto mapping_loop; 2978 } 2979 KASSERT((scratch_bp->b_flags & B_KVAALLOC) != 0, 2980 ("scratch bp !B_KVAALLOC %p", scratch_bp)); 2981 setbufkva(bp, (vm_offset_t)scratch_bp->b_kvaalloc, 2982 scratch_bp->b_kvasize, gbflags); 2983 2984 /* Get rid of the scratch buffer. */ 2985 scratch_bp->b_kvasize = 0; 2986 scratch_bp->b_flags |= B_INVAL; 2987 scratch_bp->b_flags &= ~(B_UNMAPPED | B_KVAALLOC); 2988 brelse(scratch_bp); 2989 } 2990 if (!need_mapping) 2991 return; 2992 2993has_addr: 2994 bp->b_saveaddr = bp->b_kvabase; 2995 bp->b_data = bp->b_saveaddr; /* b_offset is handled by bpmap_qenter */ 2996 bp->b_flags &= ~B_UNMAPPED; 2997 BUF_CHECK_MAPPED(bp); 2998 bpmap_qenter(bp); 2999} 3000 3001/* 3002 * getblk: 3003 * 3004 * Get a block given a specified block and offset into a file/device. 3005 * The buffers B_DONE bit will be cleared on return, making it almost 3006 * ready for an I/O initiation. B_INVAL may or may not be set on 3007 * return. The caller should clear B_INVAL prior to initiating a 3008 * READ. 3009 * 3010 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 3011 * an existing buffer. 3012 * 3013 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 3014 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 3015 * and then cleared based on the backing VM. If the previous buffer is 3016 * non-0-sized but invalid, B_CACHE will be cleared. 3017 * 3018 * If getblk() must create a new buffer, the new buffer is returned with 3019 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 3020 * case it is returned with B_INVAL clear and B_CACHE set based on the 3021 * backing VM. 3022 * 3023 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 3024 * B_CACHE bit is clear. 3025 * 3026 * What this means, basically, is that the caller should use B_CACHE to 3027 * determine whether the buffer is fully valid or not and should clear 3028 * B_INVAL prior to issuing a read. If the caller intends to validate 3029 * the buffer by loading its data area with something, the caller needs 3030 * to clear B_INVAL. If the caller does this without issuing an I/O, 3031 * the caller should set B_CACHE ( as an optimization ), else the caller 3032 * should issue the I/O and biodone() will set B_CACHE if the I/O was 3033 * a write attempt or if it was a successfull read. If the caller 3034 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 3035 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 3036 */ 3037struct buf * 3038getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3039 int flags) 3040{ 3041 struct buf *bp; 3042 struct bufobj *bo; 3043 int bsize, error, maxsize, vmio; 3044 off_t offset; 3045 3046 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 3047 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3048 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3049 ASSERT_VOP_LOCKED(vp, "getblk"); 3050 if (size > MAXBSIZE) 3051 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 3052 if (!unmapped_buf_allowed) 3053 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3054 3055 bo = &vp->v_bufobj; 3056loop: 3057 BO_RLOCK(bo); 3058 bp = gbincore(bo, blkno); 3059 if (bp != NULL) { 3060 int lockflags; 3061 /* 3062 * Buffer is in-core. If the buffer is not busy nor managed, 3063 * it must be on a queue. 3064 */ 3065 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 3066 3067 if (flags & GB_LOCK_NOWAIT) 3068 lockflags |= LK_NOWAIT; 3069 3070 error = BUF_TIMELOCK(bp, lockflags, 3071 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo); 3072 3073 /* 3074 * If we slept and got the lock we have to restart in case 3075 * the buffer changed identities. 3076 */ 3077 if (error == ENOLCK) 3078 goto loop; 3079 /* We timed out or were interrupted. */ 3080 else if (error) 3081 return (NULL); 3082 /* If recursed, assume caller knows the rules. */ 3083 else if (BUF_LOCKRECURSED(bp)) 3084 goto end; 3085 3086 /* 3087 * The buffer is locked. B_CACHE is cleared if the buffer is 3088 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 3089 * and for a VMIO buffer B_CACHE is adjusted according to the 3090 * backing VM cache. 3091 */ 3092 if (bp->b_flags & B_INVAL) 3093 bp->b_flags &= ~B_CACHE; 3094 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 3095 bp->b_flags |= B_CACHE; 3096 if (bp->b_flags & B_MANAGED) 3097 MPASS(bp->b_qindex == QUEUE_NONE); 3098 else 3099 bremfree(bp); 3100 3101 /* 3102 * check for size inconsistencies for non-VMIO case. 3103 */ 3104 if (bp->b_bcount != size) { 3105 if ((bp->b_flags & B_VMIO) == 0 || 3106 (size > bp->b_kvasize)) { 3107 if (bp->b_flags & B_DELWRI) { 3108 /* 3109 * If buffer is pinned and caller does 3110 * not want sleep waiting for it to be 3111 * unpinned, bail out 3112 * */ 3113 if (bp->b_pin_count > 0) { 3114 if (flags & GB_LOCK_NOWAIT) { 3115 bqrelse(bp); 3116 return (NULL); 3117 } else { 3118 bunpin_wait(bp); 3119 } 3120 } 3121 bp->b_flags |= B_NOCACHE; 3122 bwrite(bp); 3123 } else { 3124 if (LIST_EMPTY(&bp->b_dep)) { 3125 bp->b_flags |= B_RELBUF; 3126 brelse(bp); 3127 } else { 3128 bp->b_flags |= B_NOCACHE; 3129 bwrite(bp); 3130 } 3131 } 3132 goto loop; 3133 } 3134 } 3135 3136 /* 3137 * Handle the case of unmapped buffer which should 3138 * become mapped, or the buffer for which KVA 3139 * reservation is requested. 3140 */ 3141 bp_unmapped_get_kva(bp, blkno, size, flags); 3142 3143 /* 3144 * If the size is inconsistant in the VMIO case, we can resize 3145 * the buffer. This might lead to B_CACHE getting set or 3146 * cleared. If the size has not changed, B_CACHE remains 3147 * unchanged from its previous state. 3148 */ 3149 if (bp->b_bcount != size) 3150 allocbuf(bp, size); 3151 3152 KASSERT(bp->b_offset != NOOFFSET, 3153 ("getblk: no buffer offset")); 3154 3155 /* 3156 * A buffer with B_DELWRI set and B_CACHE clear must 3157 * be committed before we can return the buffer in 3158 * order to prevent the caller from issuing a read 3159 * ( due to B_CACHE not being set ) and overwriting 3160 * it. 3161 * 3162 * Most callers, including NFS and FFS, need this to 3163 * operate properly either because they assume they 3164 * can issue a read if B_CACHE is not set, or because 3165 * ( for example ) an uncached B_DELWRI might loop due 3166 * to softupdates re-dirtying the buffer. In the latter 3167 * case, B_CACHE is set after the first write completes, 3168 * preventing further loops. 3169 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 3170 * above while extending the buffer, we cannot allow the 3171 * buffer to remain with B_CACHE set after the write 3172 * completes or it will represent a corrupt state. To 3173 * deal with this we set B_NOCACHE to scrap the buffer 3174 * after the write. 3175 * 3176 * We might be able to do something fancy, like setting 3177 * B_CACHE in bwrite() except if B_DELWRI is already set, 3178 * so the below call doesn't set B_CACHE, but that gets real 3179 * confusing. This is much easier. 3180 */ 3181 3182 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 3183 bp->b_flags |= B_NOCACHE; 3184 bwrite(bp); 3185 goto loop; 3186 } 3187 bp->b_flags &= ~B_DONE; 3188 } else { 3189 /* 3190 * Buffer is not in-core, create new buffer. The buffer 3191 * returned by getnewbuf() is locked. Note that the returned 3192 * buffer is also considered valid (not marked B_INVAL). 3193 */ 3194 BO_RUNLOCK(bo); 3195 /* 3196 * If the user does not want us to create the buffer, bail out 3197 * here. 3198 */ 3199 if (flags & GB_NOCREAT) 3200 return NULL; 3201 if (numfreebuffers == 0 && TD_IS_IDLETHREAD(curthread)) 3202 return NULL; 3203 3204 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize; 3205 offset = blkno * bsize; 3206 vmio = vp->v_object != NULL; 3207 if (vmio) { 3208 maxsize = size + (offset & PAGE_MASK); 3209 } else { 3210 maxsize = size; 3211 /* Do not allow non-VMIO notmapped buffers. */ 3212 flags &= ~GB_UNMAPPED; 3213 } 3214 maxsize = imax(maxsize, bsize); 3215 3216 bp = getnewbuf(vp, slpflag, slptimeo, size, maxsize, flags); 3217 if (bp == NULL) { 3218 if (slpflag || slptimeo) 3219 return NULL; 3220 goto loop; 3221 } 3222 3223 /* 3224 * This code is used to make sure that a buffer is not 3225 * created while the getnewbuf routine is blocked. 3226 * This can be a problem whether the vnode is locked or not. 3227 * If the buffer is created out from under us, we have to 3228 * throw away the one we just created. 3229 * 3230 * Note: this must occur before we associate the buffer 3231 * with the vp especially considering limitations in 3232 * the splay tree implementation when dealing with duplicate 3233 * lblkno's. 3234 */ 3235 BO_LOCK(bo); 3236 if (gbincore(bo, blkno)) { 3237 BO_UNLOCK(bo); 3238 bp->b_flags |= B_INVAL; 3239 brelse(bp); 3240 goto loop; 3241 } 3242 3243 /* 3244 * Insert the buffer into the hash, so that it can 3245 * be found by incore. 3246 */ 3247 bp->b_blkno = bp->b_lblkno = blkno; 3248 bp->b_offset = offset; 3249 bgetvp(vp, bp); 3250 BO_UNLOCK(bo); 3251 3252 /* 3253 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 3254 * buffer size starts out as 0, B_CACHE will be set by 3255 * allocbuf() for the VMIO case prior to it testing the 3256 * backing store for validity. 3257 */ 3258 3259 if (vmio) { 3260 bp->b_flags |= B_VMIO; 3261 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 3262 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 3263 bp, vp->v_object, bp->b_bufobj->bo_object)); 3264 } else { 3265 bp->b_flags &= ~B_VMIO; 3266 KASSERT(bp->b_bufobj->bo_object == NULL, 3267 ("ARGH! has b_bufobj->bo_object %p %p\n", 3268 bp, bp->b_bufobj->bo_object)); 3269 BUF_CHECK_MAPPED(bp); 3270 } 3271 3272 allocbuf(bp, size); 3273 bp->b_flags &= ~B_DONE; 3274 } 3275 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 3276 BUF_ASSERT_HELD(bp); 3277end: 3278 KASSERT(bp->b_bufobj == bo, 3279 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 3280 return (bp); 3281} 3282 3283/* 3284 * Get an empty, disassociated buffer of given size. The buffer is initially 3285 * set to B_INVAL. 3286 */ 3287struct buf * 3288geteblk(int size, int flags) 3289{ 3290 struct buf *bp; 3291 int maxsize; 3292 3293 maxsize = (size + BKVAMASK) & ~BKVAMASK; 3294 while ((bp = getnewbuf(NULL, 0, 0, size, maxsize, flags)) == NULL) { 3295 if ((flags & GB_NOWAIT_BD) && 3296 (curthread->td_pflags & TDP_BUFNEED) != 0) 3297 return (NULL); 3298 } 3299 allocbuf(bp, size); 3300 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 3301 BUF_ASSERT_HELD(bp); 3302 return (bp); 3303} 3304 3305 3306/* 3307 * This code constitutes the buffer memory from either anonymous system 3308 * memory (in the case of non-VMIO operations) or from an associated 3309 * VM object (in the case of VMIO operations). This code is able to 3310 * resize a buffer up or down. 3311 * 3312 * Note that this code is tricky, and has many complications to resolve 3313 * deadlock or inconsistant data situations. Tread lightly!!! 3314 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 3315 * the caller. Calling this code willy nilly can result in the loss of data. 3316 * 3317 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 3318 * B_CACHE for the non-VMIO case. 3319 */ 3320 3321int 3322allocbuf(struct buf *bp, int size) 3323{ 3324 int newbsize, mbsize; 3325 int i; 3326 3327 BUF_ASSERT_HELD(bp); 3328 3329 if (bp->b_kvasize < size) 3330 panic("allocbuf: buffer too small"); 3331 3332 if ((bp->b_flags & B_VMIO) == 0) { 3333 caddr_t origbuf; 3334 int origbufsize; 3335 /* 3336 * Just get anonymous memory from the kernel. Don't 3337 * mess with B_CACHE. 3338 */ 3339 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3340 if (bp->b_flags & B_MALLOC) 3341 newbsize = mbsize; 3342 else 3343 newbsize = round_page(size); 3344 3345 if (newbsize < bp->b_bufsize) { 3346 /* 3347 * malloced buffers are not shrunk 3348 */ 3349 if (bp->b_flags & B_MALLOC) { 3350 if (newbsize) { 3351 bp->b_bcount = size; 3352 } else { 3353 free(bp->b_data, M_BIOBUF); 3354 if (bp->b_bufsize) { 3355 atomic_subtract_long( 3356 &bufmallocspace, 3357 bp->b_bufsize); 3358 bufspacewakeup(); 3359 bp->b_bufsize = 0; 3360 } 3361 bp->b_saveaddr = bp->b_kvabase; 3362 bp->b_data = bp->b_saveaddr; 3363 bp->b_bcount = 0; 3364 bp->b_flags &= ~B_MALLOC; 3365 } 3366 return 1; 3367 } 3368 vm_hold_free_pages(bp, newbsize); 3369 } else if (newbsize > bp->b_bufsize) { 3370 /* 3371 * We only use malloced memory on the first allocation. 3372 * and revert to page-allocated memory when the buffer 3373 * grows. 3374 */ 3375 /* 3376 * There is a potential smp race here that could lead 3377 * to bufmallocspace slightly passing the max. It 3378 * is probably extremely rare and not worth worrying 3379 * over. 3380 */ 3381 if ( (bufmallocspace < maxbufmallocspace) && 3382 (bp->b_bufsize == 0) && 3383 (mbsize <= PAGE_SIZE/2)) { 3384 3385 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 3386 bp->b_bufsize = mbsize; 3387 bp->b_bcount = size; 3388 bp->b_flags |= B_MALLOC; 3389 atomic_add_long(&bufmallocspace, mbsize); 3390 return 1; 3391 } 3392 origbuf = NULL; 3393 origbufsize = 0; 3394 /* 3395 * If the buffer is growing on its other-than-first allocation, 3396 * then we revert to the page-allocation scheme. 3397 */ 3398 if (bp->b_flags & B_MALLOC) { 3399 origbuf = bp->b_data; 3400 origbufsize = bp->b_bufsize; 3401 bp->b_data = bp->b_kvabase; 3402 if (bp->b_bufsize) { 3403 atomic_subtract_long(&bufmallocspace, 3404 bp->b_bufsize); 3405 bufspacewakeup(); 3406 bp->b_bufsize = 0; 3407 } 3408 bp->b_flags &= ~B_MALLOC; 3409 newbsize = round_page(newbsize); 3410 } 3411 vm_hold_load_pages( 3412 bp, 3413 (vm_offset_t) bp->b_data + bp->b_bufsize, 3414 (vm_offset_t) bp->b_data + newbsize); 3415 if (origbuf) { 3416 bcopy(origbuf, bp->b_data, origbufsize); 3417 free(origbuf, M_BIOBUF); 3418 } 3419 } 3420 } else { 3421 int desiredpages; 3422 3423 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3424 desiredpages = (size == 0) ? 0 : 3425 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 3426 3427 if (bp->b_flags & B_MALLOC) 3428 panic("allocbuf: VMIO buffer can't be malloced"); 3429 /* 3430 * Set B_CACHE initially if buffer is 0 length or will become 3431 * 0-length. 3432 */ 3433 if (size == 0 || bp->b_bufsize == 0) 3434 bp->b_flags |= B_CACHE; 3435 3436 if (newbsize < bp->b_bufsize) { 3437 /* 3438 * DEV_BSIZE aligned new buffer size is less then the 3439 * DEV_BSIZE aligned existing buffer size. Figure out 3440 * if we have to remove any pages. 3441 */ 3442 if (desiredpages < bp->b_npages) { 3443 vm_page_t m; 3444 3445 if ((bp->b_flags & B_UNMAPPED) == 0) { 3446 BUF_CHECK_MAPPED(bp); 3447 pmap_qremove((vm_offset_t)trunc_page( 3448 (vm_offset_t)bp->b_data) + 3449 (desiredpages << PAGE_SHIFT), 3450 (bp->b_npages - desiredpages)); 3451 } else 3452 BUF_CHECK_UNMAPPED(bp); 3453 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 3454 for (i = desiredpages; i < bp->b_npages; i++) { 3455 /* 3456 * the page is not freed here -- it 3457 * is the responsibility of 3458 * vnode_pager_setsize 3459 */ 3460 m = bp->b_pages[i]; 3461 KASSERT(m != bogus_page, 3462 ("allocbuf: bogus page found")); 3463 while (vm_page_sleep_if_busy(m, 3464 "biodep")) 3465 continue; 3466 3467 bp->b_pages[i] = NULL; 3468 vm_page_lock(m); 3469 vm_page_unwire(m, 0); 3470 vm_page_unlock(m); 3471 } 3472 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 3473 bp->b_npages = desiredpages; 3474 } 3475 } else if (size > bp->b_bcount) { 3476 /* 3477 * We are growing the buffer, possibly in a 3478 * byte-granular fashion. 3479 */ 3480 vm_object_t obj; 3481 vm_offset_t toff; 3482 vm_offset_t tinc; 3483 3484 /* 3485 * Step 1, bring in the VM pages from the object, 3486 * allocating them if necessary. We must clear 3487 * B_CACHE if these pages are not valid for the 3488 * range covered by the buffer. 3489 */ 3490 3491 obj = bp->b_bufobj->bo_object; 3492 3493 VM_OBJECT_WLOCK(obj); 3494 while (bp->b_npages < desiredpages) { 3495 vm_page_t m; 3496 3497 /* 3498 * We must allocate system pages since blocking 3499 * here could interfere with paging I/O, no 3500 * matter which process we are. 3501 * 3502 * Only exclusive busy can be tested here. 3503 * Blocking on shared busy might lead to 3504 * deadlocks once allocbuf() is called after 3505 * pages are vfs_busy_pages(). 3506 */ 3507 m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) + 3508 bp->b_npages, VM_ALLOC_NOBUSY | 3509 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED | 3510 VM_ALLOC_IGN_SBUSY | 3511 VM_ALLOC_COUNT(desiredpages - bp->b_npages)); 3512 if (m->valid == 0) 3513 bp->b_flags &= ~B_CACHE; 3514 bp->b_pages[bp->b_npages] = m; 3515 ++bp->b_npages; 3516 } 3517 3518 /* 3519 * Step 2. We've loaded the pages into the buffer, 3520 * we have to figure out if we can still have B_CACHE 3521 * set. Note that B_CACHE is set according to the 3522 * byte-granular range ( bcount and size ), new the 3523 * aligned range ( newbsize ). 3524 * 3525 * The VM test is against m->valid, which is DEV_BSIZE 3526 * aligned. Needless to say, the validity of the data 3527 * needs to also be DEV_BSIZE aligned. Note that this 3528 * fails with NFS if the server or some other client 3529 * extends the file's EOF. If our buffer is resized, 3530 * B_CACHE may remain set! XXX 3531 */ 3532 3533 toff = bp->b_bcount; 3534 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 3535 3536 while ((bp->b_flags & B_CACHE) && toff < size) { 3537 vm_pindex_t pi; 3538 3539 if (tinc > (size - toff)) 3540 tinc = size - toff; 3541 3542 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 3543 PAGE_SHIFT; 3544 3545 vfs_buf_test_cache( 3546 bp, 3547 bp->b_offset, 3548 toff, 3549 tinc, 3550 bp->b_pages[pi] 3551 ); 3552 toff += tinc; 3553 tinc = PAGE_SIZE; 3554 } 3555 VM_OBJECT_WUNLOCK(obj); 3556 3557 /* 3558 * Step 3, fixup the KVM pmap. 3559 */ 3560 if ((bp->b_flags & B_UNMAPPED) == 0) 3561 bpmap_qenter(bp); 3562 else 3563 BUF_CHECK_UNMAPPED(bp); 3564 } 3565 } 3566 if (newbsize < bp->b_bufsize) 3567 bufspacewakeup(); 3568 bp->b_bufsize = newbsize; /* actual buffer allocation */ 3569 bp->b_bcount = size; /* requested buffer size */ 3570 return 1; 3571} 3572 3573extern int inflight_transient_maps; 3574 3575void 3576biodone(struct bio *bp) 3577{ 3578 struct mtx *mtxp; 3579 void (*done)(struct bio *); 3580 vm_offset_t start, end; 3581 int transient; 3582 3583 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3584 mtx_lock(mtxp); 3585 bp->bio_flags |= BIO_DONE; 3586 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) { 3587 start = trunc_page((vm_offset_t)bp->bio_data); 3588 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length); 3589 transient = 1; 3590 } else { 3591 transient = 0; 3592 start = end = 0; 3593 } 3594 done = bp->bio_done; 3595 if (done == NULL) 3596 wakeup(bp); 3597 mtx_unlock(mtxp); 3598 if (done != NULL) 3599 done(bp); 3600 if (transient) { 3601 pmap_qremove(start, OFF_TO_IDX(end - start)); 3602 vmem_free(transient_arena, start, end - start); 3603 atomic_add_int(&inflight_transient_maps, -1); 3604 } 3605} 3606 3607/* 3608 * Wait for a BIO to finish. 3609 * 3610 * XXX: resort to a timeout for now. The optimal locking (if any) for this 3611 * case is not yet clear. 3612 */ 3613int 3614biowait(struct bio *bp, const char *wchan) 3615{ 3616 struct mtx *mtxp; 3617 3618 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3619 mtx_lock(mtxp); 3620 while ((bp->bio_flags & BIO_DONE) == 0) 3621 msleep(bp, mtxp, PRIBIO, wchan, hz / 10); 3622 mtx_unlock(mtxp); 3623 if (bp->bio_error != 0) 3624 return (bp->bio_error); 3625 if (!(bp->bio_flags & BIO_ERROR)) 3626 return (0); 3627 return (EIO); 3628} 3629 3630void 3631biofinish(struct bio *bp, struct devstat *stat, int error) 3632{ 3633 3634 if (error) { 3635 bp->bio_error = error; 3636 bp->bio_flags |= BIO_ERROR; 3637 } 3638 if (stat != NULL) 3639 devstat_end_transaction_bio(stat, bp); 3640 biodone(bp); 3641} 3642 3643/* 3644 * bufwait: 3645 * 3646 * Wait for buffer I/O completion, returning error status. The buffer 3647 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3648 * error and cleared. 3649 */ 3650int 3651bufwait(struct buf *bp) 3652{ 3653 if (bp->b_iocmd == BIO_READ) 3654 bwait(bp, PRIBIO, "biord"); 3655 else 3656 bwait(bp, PRIBIO, "biowr"); 3657 if (bp->b_flags & B_EINTR) { 3658 bp->b_flags &= ~B_EINTR; 3659 return (EINTR); 3660 } 3661 if (bp->b_ioflags & BIO_ERROR) { 3662 return (bp->b_error ? bp->b_error : EIO); 3663 } else { 3664 return (0); 3665 } 3666} 3667 3668 /* 3669 * Call back function from struct bio back up to struct buf. 3670 */ 3671static void 3672bufdonebio(struct bio *bip) 3673{ 3674 struct buf *bp; 3675 3676 bp = bip->bio_caller2; 3677 bp->b_resid = bp->b_bcount - bip->bio_completed; 3678 bp->b_resid = bip->bio_resid; /* XXX: remove */ 3679 bp->b_ioflags = bip->bio_flags; 3680 bp->b_error = bip->bio_error; 3681 if (bp->b_error) 3682 bp->b_ioflags |= BIO_ERROR; 3683 bufdone(bp); 3684 g_destroy_bio(bip); 3685} 3686 3687void 3688dev_strategy(struct cdev *dev, struct buf *bp) 3689{ 3690 struct cdevsw *csw; 3691 int ref; 3692 3693 KASSERT(dev->si_refcount > 0, 3694 ("dev_strategy on un-referenced struct cdev *(%s) %p", 3695 devtoname(dev), dev)); 3696 3697 csw = dev_refthread(dev, &ref); 3698 dev_strategy_csw(dev, csw, bp); 3699 dev_relthread(dev, ref); 3700} 3701 3702void 3703dev_strategy_csw(struct cdev *dev, struct cdevsw *csw, struct buf *bp) 3704{ 3705 struct bio *bip; 3706 3707 KASSERT(bp->b_iocmd == BIO_READ || bp->b_iocmd == BIO_WRITE, 3708 ("b_iocmd botch")); 3709 KASSERT(((dev->si_flags & SI_ETERNAL) != 0 && csw != NULL) || 3710 dev->si_threadcount > 0, 3711 ("dev_strategy_csw threadcount cdev *(%s) %p", devtoname(dev), 3712 dev)); 3713 if (csw == NULL) { 3714 bp->b_error = ENXIO; 3715 bp->b_ioflags = BIO_ERROR; 3716 bufdone(bp); 3717 return; 3718 } 3719 for (;;) { 3720 bip = g_new_bio(); 3721 if (bip != NULL) 3722 break; 3723 /* Try again later */ 3724 tsleep(&bp, PRIBIO, "dev_strat", hz/10); 3725 } 3726 bip->bio_cmd = bp->b_iocmd; 3727 bip->bio_offset = bp->b_iooffset; 3728 bip->bio_length = bp->b_bcount; 3729 bip->bio_bcount = bp->b_bcount; /* XXX: remove */ 3730 bdata2bio(bp, bip); 3731 bip->bio_done = bufdonebio; 3732 bip->bio_caller2 = bp; 3733 bip->bio_dev = dev; 3734 (*csw->d_strategy)(bip); 3735} 3736 3737/* 3738 * bufdone: 3739 * 3740 * Finish I/O on a buffer, optionally calling a completion function. 3741 * This is usually called from an interrupt so process blocking is 3742 * not allowed. 3743 * 3744 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3745 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3746 * assuming B_INVAL is clear. 3747 * 3748 * For the VMIO case, we set B_CACHE if the op was a read and no 3749 * read error occured, or if the op was a write. B_CACHE is never 3750 * set if the buffer is invalid or otherwise uncacheable. 3751 * 3752 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3753 * initiator to leave B_INVAL set to brelse the buffer out of existance 3754 * in the biodone routine. 3755 */ 3756void 3757bufdone(struct buf *bp) 3758{ 3759 struct bufobj *dropobj; 3760 void (*biodone)(struct buf *); 3761 3762 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 3763 dropobj = NULL; 3764 3765 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 3766 BUF_ASSERT_HELD(bp); 3767 3768 runningbufwakeup(bp); 3769 if (bp->b_iocmd == BIO_WRITE) 3770 dropobj = bp->b_bufobj; 3771 /* call optional completion function if requested */ 3772 if (bp->b_iodone != NULL) { 3773 biodone = bp->b_iodone; 3774 bp->b_iodone = NULL; 3775 (*biodone) (bp); 3776 if (dropobj) 3777 bufobj_wdrop(dropobj); 3778 return; 3779 } 3780 3781 bufdone_finish(bp); 3782 3783 if (dropobj) 3784 bufobj_wdrop(dropobj); 3785} 3786 3787void 3788bufdone_finish(struct buf *bp) 3789{ 3790 BUF_ASSERT_HELD(bp); 3791 3792 if (!LIST_EMPTY(&bp->b_dep)) 3793 buf_complete(bp); 3794 3795 if (bp->b_flags & B_VMIO) { 3796 vm_ooffset_t foff; 3797 vm_page_t m; 3798 vm_object_t obj; 3799 struct vnode *vp; 3800 int bogus, i, iosize; 3801 3802 obj = bp->b_bufobj->bo_object; 3803 KASSERT(obj->paging_in_progress >= bp->b_npages, 3804 ("biodone_finish: paging in progress(%d) < b_npages(%d)", 3805 obj->paging_in_progress, bp->b_npages)); 3806 3807 vp = bp->b_vp; 3808 KASSERT(vp->v_holdcnt > 0, 3809 ("biodone_finish: vnode %p has zero hold count", vp)); 3810 KASSERT(vp->v_object != NULL, 3811 ("biodone_finish: vnode %p has no vm_object", vp)); 3812 3813 foff = bp->b_offset; 3814 KASSERT(bp->b_offset != NOOFFSET, 3815 ("biodone_finish: bp %p has no buffer offset", bp)); 3816 3817 /* 3818 * Set B_CACHE if the op was a normal read and no error 3819 * occured. B_CACHE is set for writes in the b*write() 3820 * routines. 3821 */ 3822 iosize = bp->b_bcount - bp->b_resid; 3823 if (bp->b_iocmd == BIO_READ && 3824 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 3825 !(bp->b_ioflags & BIO_ERROR)) { 3826 bp->b_flags |= B_CACHE; 3827 } 3828 bogus = 0; 3829 VM_OBJECT_WLOCK(obj); 3830 for (i = 0; i < bp->b_npages; i++) { 3831 int bogusflag = 0; 3832 int resid; 3833 3834 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 3835 if (resid > iosize) 3836 resid = iosize; 3837 3838 /* 3839 * cleanup bogus pages, restoring the originals 3840 */ 3841 m = bp->b_pages[i]; 3842 if (m == bogus_page) { 3843 bogus = bogusflag = 1; 3844 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3845 if (m == NULL) 3846 panic("biodone: page disappeared!"); 3847 bp->b_pages[i] = m; 3848 } 3849 KASSERT(OFF_TO_IDX(foff) == m->pindex, 3850 ("biodone_finish: foff(%jd)/pindex(%ju) mismatch", 3851 (intmax_t)foff, (uintmax_t)m->pindex)); 3852 3853 /* 3854 * In the write case, the valid and clean bits are 3855 * already changed correctly ( see bdwrite() ), so we 3856 * only need to do this here in the read case. 3857 */ 3858 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 3859 KASSERT((m->dirty & vm_page_bits(foff & 3860 PAGE_MASK, resid)) == 0, ("bufdone_finish:" 3861 " page %p has unexpected dirty bits", m)); 3862 vfs_page_set_valid(bp, foff, m); 3863 } 3864 3865 vm_page_sunbusy(m); 3866 vm_object_pip_subtract(obj, 1); 3867 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3868 iosize -= resid; 3869 } 3870 vm_object_pip_wakeupn(obj, 0); 3871 VM_OBJECT_WUNLOCK(obj); 3872 if (bogus && (bp->b_flags & B_UNMAPPED) == 0) { 3873 BUF_CHECK_MAPPED(bp); 3874 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3875 bp->b_pages, bp->b_npages); 3876 } 3877 } 3878 3879 /* 3880 * For asynchronous completions, release the buffer now. The brelse 3881 * will do a wakeup there if necessary - so no need to do a wakeup 3882 * here in the async case. The sync case always needs to do a wakeup. 3883 */ 3884 3885 if (bp->b_flags & B_ASYNC) { 3886 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 3887 brelse(bp); 3888 else 3889 bqrelse(bp); 3890 } else 3891 bdone(bp); 3892} 3893 3894/* 3895 * This routine is called in lieu of iodone in the case of 3896 * incomplete I/O. This keeps the busy status for pages 3897 * consistant. 3898 */ 3899void 3900vfs_unbusy_pages(struct buf *bp) 3901{ 3902 int i; 3903 vm_object_t obj; 3904 vm_page_t m; 3905 3906 runningbufwakeup(bp); 3907 if (!(bp->b_flags & B_VMIO)) 3908 return; 3909 3910 obj = bp->b_bufobj->bo_object; 3911 VM_OBJECT_WLOCK(obj); 3912 for (i = 0; i < bp->b_npages; i++) { 3913 m = bp->b_pages[i]; 3914 if (m == bogus_page) { 3915 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 3916 if (!m) 3917 panic("vfs_unbusy_pages: page missing\n"); 3918 bp->b_pages[i] = m; 3919 if ((bp->b_flags & B_UNMAPPED) == 0) { 3920 BUF_CHECK_MAPPED(bp); 3921 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3922 bp->b_pages, bp->b_npages); 3923 } else 3924 BUF_CHECK_UNMAPPED(bp); 3925 } 3926 vm_object_pip_subtract(obj, 1); 3927 vm_page_sunbusy(m); 3928 } 3929 vm_object_pip_wakeupn(obj, 0); 3930 VM_OBJECT_WUNLOCK(obj); 3931} 3932 3933/* 3934 * vfs_page_set_valid: 3935 * 3936 * Set the valid bits in a page based on the supplied offset. The 3937 * range is restricted to the buffer's size. 3938 * 3939 * This routine is typically called after a read completes. 3940 */ 3941static void 3942vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3943{ 3944 vm_ooffset_t eoff; 3945 3946 /* 3947 * Compute the end offset, eoff, such that [off, eoff) does not span a 3948 * page boundary and eoff is not greater than the end of the buffer. 3949 * The end of the buffer, in this case, is our file EOF, not the 3950 * allocation size of the buffer. 3951 */ 3952 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 3953 if (eoff > bp->b_offset + bp->b_bcount) 3954 eoff = bp->b_offset + bp->b_bcount; 3955 3956 /* 3957 * Set valid range. This is typically the entire buffer and thus the 3958 * entire page. 3959 */ 3960 if (eoff > off) 3961 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off); 3962} 3963 3964/* 3965 * vfs_page_set_validclean: 3966 * 3967 * Set the valid bits and clear the dirty bits in a page based on the 3968 * supplied offset. The range is restricted to the buffer's size. 3969 */ 3970static void 3971vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3972{ 3973 vm_ooffset_t soff, eoff; 3974 3975 /* 3976 * Start and end offsets in buffer. eoff - soff may not cross a 3977 * page boundry or cross the end of the buffer. The end of the 3978 * buffer, in this case, is our file EOF, not the allocation size 3979 * of the buffer. 3980 */ 3981 soff = off; 3982 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3983 if (eoff > bp->b_offset + bp->b_bcount) 3984 eoff = bp->b_offset + bp->b_bcount; 3985 3986 /* 3987 * Set valid range. This is typically the entire buffer and thus the 3988 * entire page. 3989 */ 3990 if (eoff > soff) { 3991 vm_page_set_validclean( 3992 m, 3993 (vm_offset_t) (soff & PAGE_MASK), 3994 (vm_offset_t) (eoff - soff) 3995 ); 3996 } 3997} 3998 3999/* 4000 * Ensure that all buffer pages are not exclusive busied. If any page is 4001 * exclusive busy, drain it. 4002 */ 4003void 4004vfs_drain_busy_pages(struct buf *bp) 4005{ 4006 vm_page_t m; 4007 int i, last_busied; 4008 4009 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object); 4010 last_busied = 0; 4011 for (i = 0; i < bp->b_npages; i++) { 4012 m = bp->b_pages[i]; 4013 if (vm_page_xbusied(m)) { 4014 for (; last_busied < i; last_busied++) 4015 vm_page_sbusy(bp->b_pages[last_busied]); 4016 while (vm_page_xbusied(m)) { 4017 vm_page_lock(m); 4018 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4019 vm_page_busy_sleep(m, "vbpage"); 4020 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4021 } 4022 } 4023 } 4024 for (i = 0; i < last_busied; i++) 4025 vm_page_sunbusy(bp->b_pages[i]); 4026} 4027 4028/* 4029 * This routine is called before a device strategy routine. 4030 * It is used to tell the VM system that paging I/O is in 4031 * progress, and treat the pages associated with the buffer 4032 * almost as being exclusive busy. Also the object paging_in_progress 4033 * flag is handled to make sure that the object doesn't become 4034 * inconsistant. 4035 * 4036 * Since I/O has not been initiated yet, certain buffer flags 4037 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 4038 * and should be ignored. 4039 */ 4040void 4041vfs_busy_pages(struct buf *bp, int clear_modify) 4042{ 4043 int i, bogus; 4044 vm_object_t obj; 4045 vm_ooffset_t foff; 4046 vm_page_t m; 4047 4048 if (!(bp->b_flags & B_VMIO)) 4049 return; 4050 4051 obj = bp->b_bufobj->bo_object; 4052 foff = bp->b_offset; 4053 KASSERT(bp->b_offset != NOOFFSET, 4054 ("vfs_busy_pages: no buffer offset")); 4055 VM_OBJECT_WLOCK(obj); 4056 vfs_drain_busy_pages(bp); 4057 if (bp->b_bufsize != 0) 4058 vfs_setdirty_locked_object(bp); 4059 bogus = 0; 4060 for (i = 0; i < bp->b_npages; i++) { 4061 m = bp->b_pages[i]; 4062 4063 if ((bp->b_flags & B_CLUSTER) == 0) { 4064 vm_object_pip_add(obj, 1); 4065 vm_page_sbusy(m); 4066 } 4067 /* 4068 * When readying a buffer for a read ( i.e 4069 * clear_modify == 0 ), it is important to do 4070 * bogus_page replacement for valid pages in 4071 * partially instantiated buffers. Partially 4072 * instantiated buffers can, in turn, occur when 4073 * reconstituting a buffer from its VM backing store 4074 * base. We only have to do this if B_CACHE is 4075 * clear ( which causes the I/O to occur in the 4076 * first place ). The replacement prevents the read 4077 * I/O from overwriting potentially dirty VM-backed 4078 * pages. XXX bogus page replacement is, uh, bogus. 4079 * It may not work properly with small-block devices. 4080 * We need to find a better way. 4081 */ 4082 if (clear_modify) { 4083 pmap_remove_write(m); 4084 vfs_page_set_validclean(bp, foff, m); 4085 } else if (m->valid == VM_PAGE_BITS_ALL && 4086 (bp->b_flags & B_CACHE) == 0) { 4087 bp->b_pages[i] = bogus_page; 4088 bogus++; 4089 } 4090 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4091 } 4092 VM_OBJECT_WUNLOCK(obj); 4093 if (bogus && (bp->b_flags & B_UNMAPPED) == 0) { 4094 BUF_CHECK_MAPPED(bp); 4095 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4096 bp->b_pages, bp->b_npages); 4097 } 4098} 4099 4100/* 4101 * vfs_bio_set_valid: 4102 * 4103 * Set the range within the buffer to valid. The range is 4104 * relative to the beginning of the buffer, b_offset. Note that 4105 * b_offset itself may be offset from the beginning of the first 4106 * page. 4107 */ 4108void 4109vfs_bio_set_valid(struct buf *bp, int base, int size) 4110{ 4111 int i, n; 4112 vm_page_t m; 4113 4114 if (!(bp->b_flags & B_VMIO)) 4115 return; 4116 4117 /* 4118 * Fixup base to be relative to beginning of first page. 4119 * Set initial n to be the maximum number of bytes in the 4120 * first page that can be validated. 4121 */ 4122 base += (bp->b_offset & PAGE_MASK); 4123 n = PAGE_SIZE - (base & PAGE_MASK); 4124 4125 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4126 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4127 m = bp->b_pages[i]; 4128 if (n > size) 4129 n = size; 4130 vm_page_set_valid_range(m, base & PAGE_MASK, n); 4131 base += n; 4132 size -= n; 4133 n = PAGE_SIZE; 4134 } 4135 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4136} 4137 4138/* 4139 * vfs_bio_clrbuf: 4140 * 4141 * If the specified buffer is a non-VMIO buffer, clear the entire 4142 * buffer. If the specified buffer is a VMIO buffer, clear and 4143 * validate only the previously invalid portions of the buffer. 4144 * This routine essentially fakes an I/O, so we need to clear 4145 * BIO_ERROR and B_INVAL. 4146 * 4147 * Note that while we only theoretically need to clear through b_bcount, 4148 * we go ahead and clear through b_bufsize. 4149 */ 4150void 4151vfs_bio_clrbuf(struct buf *bp) 4152{ 4153 int i, j, mask, sa, ea, slide; 4154 4155 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 4156 clrbuf(bp); 4157 return; 4158 } 4159 bp->b_flags &= ~B_INVAL; 4160 bp->b_ioflags &= ~BIO_ERROR; 4161 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4162 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 4163 (bp->b_offset & PAGE_MASK) == 0) { 4164 if (bp->b_pages[0] == bogus_page) 4165 goto unlock; 4166 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 4167 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object); 4168 if ((bp->b_pages[0]->valid & mask) == mask) 4169 goto unlock; 4170 if ((bp->b_pages[0]->valid & mask) == 0) { 4171 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize); 4172 bp->b_pages[0]->valid |= mask; 4173 goto unlock; 4174 } 4175 } 4176 sa = bp->b_offset & PAGE_MASK; 4177 slide = 0; 4178 for (i = 0; i < bp->b_npages; i++, sa = 0) { 4179 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize); 4180 ea = slide & PAGE_MASK; 4181 if (ea == 0) 4182 ea = PAGE_SIZE; 4183 if (bp->b_pages[i] == bogus_page) 4184 continue; 4185 j = sa / DEV_BSIZE; 4186 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 4187 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object); 4188 if ((bp->b_pages[i]->valid & mask) == mask) 4189 continue; 4190 if ((bp->b_pages[i]->valid & mask) == 0) 4191 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa); 4192 else { 4193 for (; sa < ea; sa += DEV_BSIZE, j++) { 4194 if ((bp->b_pages[i]->valid & (1 << j)) == 0) { 4195 pmap_zero_page_area(bp->b_pages[i], 4196 sa, DEV_BSIZE); 4197 } 4198 } 4199 } 4200 bp->b_pages[i]->valid |= mask; 4201 } 4202unlock: 4203 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4204 bp->b_resid = 0; 4205} 4206 4207void 4208vfs_bio_bzero_buf(struct buf *bp, int base, int size) 4209{ 4210 vm_page_t m; 4211 int i, n; 4212 4213 if ((bp->b_flags & B_UNMAPPED) == 0) { 4214 BUF_CHECK_MAPPED(bp); 4215 bzero(bp->b_data + base, size); 4216 } else { 4217 BUF_CHECK_UNMAPPED(bp); 4218 n = PAGE_SIZE - (base & PAGE_MASK); 4219 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4220 m = bp->b_pages[i]; 4221 if (n > size) 4222 n = size; 4223 pmap_zero_page_area(m, base & PAGE_MASK, n); 4224 base += n; 4225 size -= n; 4226 n = PAGE_SIZE; 4227 } 4228 } 4229} 4230 4231/* 4232 * vm_hold_load_pages and vm_hold_free_pages get pages into 4233 * a buffers address space. The pages are anonymous and are 4234 * not associated with a file object. 4235 */ 4236static void 4237vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4238{ 4239 vm_offset_t pg; 4240 vm_page_t p; 4241 int index; 4242 4243 BUF_CHECK_MAPPED(bp); 4244 4245 to = round_page(to); 4246 from = round_page(from); 4247 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4248 4249 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 4250tryagain: 4251 /* 4252 * note: must allocate system pages since blocking here 4253 * could interfere with paging I/O, no matter which 4254 * process we are. 4255 */ 4256 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ | 4257 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT)); 4258 if (p == NULL) { 4259 VM_WAIT; 4260 goto tryagain; 4261 } 4262 pmap_qenter(pg, &p, 1); 4263 bp->b_pages[index] = p; 4264 } 4265 bp->b_npages = index; 4266} 4267 4268/* Return pages associated with this buf to the vm system */ 4269static void 4270vm_hold_free_pages(struct buf *bp, int newbsize) 4271{ 4272 vm_offset_t from; 4273 vm_page_t p; 4274 int index, newnpages; 4275 4276 BUF_CHECK_MAPPED(bp); 4277 4278 from = round_page((vm_offset_t)bp->b_data + newbsize); 4279 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4280 if (bp->b_npages > newnpages) 4281 pmap_qremove(from, bp->b_npages - newnpages); 4282 for (index = newnpages; index < bp->b_npages; index++) { 4283 p = bp->b_pages[index]; 4284 bp->b_pages[index] = NULL; 4285 if (vm_page_sbusied(p)) 4286 printf("vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 4287 (intmax_t)bp->b_blkno, (intmax_t)bp->b_lblkno); 4288 p->wire_count--; 4289 vm_page_free(p); 4290 atomic_subtract_int(&cnt.v_wire_count, 1); 4291 } 4292 bp->b_npages = newnpages; 4293} 4294 4295/* 4296 * Map an IO request into kernel virtual address space. 4297 * 4298 * All requests are (re)mapped into kernel VA space. 4299 * Notice that we use b_bufsize for the size of the buffer 4300 * to be mapped. b_bcount might be modified by the driver. 4301 * 4302 * Note that even if the caller determines that the address space should 4303 * be valid, a race or a smaller-file mapped into a larger space may 4304 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 4305 * check the return value. 4306 */ 4307int 4308vmapbuf(struct buf *bp, int mapbuf) 4309{ 4310 caddr_t kva; 4311 vm_prot_t prot; 4312 int pidx; 4313 4314 if (bp->b_bufsize < 0) 4315 return (-1); 4316 prot = VM_PROT_READ; 4317 if (bp->b_iocmd == BIO_READ) 4318 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 4319 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 4320 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages, 4321 btoc(MAXPHYS))) < 0) 4322 return (-1); 4323 bp->b_npages = pidx; 4324 if (mapbuf || !unmapped_buf_allowed) { 4325 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx); 4326 kva = bp->b_saveaddr; 4327 bp->b_saveaddr = bp->b_data; 4328 bp->b_data = kva + (((vm_offset_t)bp->b_data) & PAGE_MASK); 4329 bp->b_flags &= ~B_UNMAPPED; 4330 } else { 4331 bp->b_flags |= B_UNMAPPED; 4332 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK; 4333 bp->b_saveaddr = bp->b_data; 4334 bp->b_data = unmapped_buf; 4335 } 4336 return(0); 4337} 4338 4339/* 4340 * Free the io map PTEs associated with this IO operation. 4341 * We also invalidate the TLB entries and restore the original b_addr. 4342 */ 4343void 4344vunmapbuf(struct buf *bp) 4345{ 4346 int npages; 4347 4348 npages = bp->b_npages; 4349 if (bp->b_flags & B_UNMAPPED) 4350 bp->b_flags &= ~B_UNMAPPED; 4351 else 4352 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 4353 vm_page_unhold_pages(bp->b_pages, npages); 4354 4355 bp->b_data = bp->b_saveaddr; 4356} 4357 4358void 4359bdone(struct buf *bp) 4360{ 4361 struct mtx *mtxp; 4362 4363 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4364 mtx_lock(mtxp); 4365 bp->b_flags |= B_DONE; 4366 wakeup(bp); 4367 mtx_unlock(mtxp); 4368} 4369 4370void 4371bwait(struct buf *bp, u_char pri, const char *wchan) 4372{ 4373 struct mtx *mtxp; 4374 4375 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4376 mtx_lock(mtxp); 4377 while ((bp->b_flags & B_DONE) == 0) 4378 msleep(bp, mtxp, pri, wchan, 0); 4379 mtx_unlock(mtxp); 4380} 4381 4382int 4383bufsync(struct bufobj *bo, int waitfor) 4384{ 4385 4386 return (VOP_FSYNC(bo->__bo_vnode, waitfor, curthread)); 4387} 4388 4389void 4390bufstrategy(struct bufobj *bo, struct buf *bp) 4391{ 4392 int i = 0; 4393 struct vnode *vp; 4394 4395 vp = bp->b_vp; 4396 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 4397 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 4398 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 4399 i = VOP_STRATEGY(vp, bp); 4400 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 4401} 4402 4403void 4404bufobj_wrefl(struct bufobj *bo) 4405{ 4406 4407 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4408 ASSERT_BO_WLOCKED(bo); 4409 bo->bo_numoutput++; 4410} 4411 4412void 4413bufobj_wref(struct bufobj *bo) 4414{ 4415 4416 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4417 BO_LOCK(bo); 4418 bo->bo_numoutput++; 4419 BO_UNLOCK(bo); 4420} 4421 4422void 4423bufobj_wdrop(struct bufobj *bo) 4424{ 4425 4426 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 4427 BO_LOCK(bo); 4428 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 4429 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 4430 bo->bo_flag &= ~BO_WWAIT; 4431 wakeup(&bo->bo_numoutput); 4432 } 4433 BO_UNLOCK(bo); 4434} 4435 4436int 4437bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 4438{ 4439 int error; 4440 4441 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 4442 ASSERT_BO_WLOCKED(bo); 4443 error = 0; 4444 while (bo->bo_numoutput) { 4445 bo->bo_flag |= BO_WWAIT; 4446 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo), 4447 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 4448 if (error) 4449 break; 4450 } 4451 return (error); 4452} 4453 4454void 4455bpin(struct buf *bp) 4456{ 4457 struct mtx *mtxp; 4458 4459 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4460 mtx_lock(mtxp); 4461 bp->b_pin_count++; 4462 mtx_unlock(mtxp); 4463} 4464 4465void 4466bunpin(struct buf *bp) 4467{ 4468 struct mtx *mtxp; 4469 4470 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4471 mtx_lock(mtxp); 4472 if (--bp->b_pin_count == 0) 4473 wakeup(bp); 4474 mtx_unlock(mtxp); 4475} 4476 4477void 4478bunpin_wait(struct buf *bp) 4479{ 4480 struct mtx *mtxp; 4481 4482 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4483 mtx_lock(mtxp); 4484 while (bp->b_pin_count > 0) 4485 msleep(bp, mtxp, PRIBIO, "bwunpin", 0); 4486 mtx_unlock(mtxp); 4487} 4488 4489/* 4490 * Set bio_data or bio_ma for struct bio from the struct buf. 4491 */ 4492void 4493bdata2bio(struct buf *bp, struct bio *bip) 4494{ 4495 4496 if ((bp->b_flags & B_UNMAPPED) != 0) { 4497 KASSERT(unmapped_buf_allowed, ("unmapped")); 4498 bip->bio_ma = bp->b_pages; 4499 bip->bio_ma_n = bp->b_npages; 4500 bip->bio_data = unmapped_buf; 4501 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 4502 bip->bio_flags |= BIO_UNMAPPED; 4503 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) / 4504 PAGE_SIZE == bp->b_npages, 4505 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset, 4506 (long long)bip->bio_length, bip->bio_ma_n)); 4507 } else { 4508 bip->bio_data = bp->b_data; 4509 bip->bio_ma = NULL; 4510 } 4511} 4512 4513#include "opt_ddb.h" 4514#ifdef DDB 4515#include <ddb/ddb.h> 4516 4517/* DDB command to show buffer data */ 4518DB_SHOW_COMMAND(buffer, db_show_buffer) 4519{ 4520 /* get args */ 4521 struct buf *bp = (struct buf *)addr; 4522 4523 if (!have_addr) { 4524 db_printf("usage: show buffer <addr>\n"); 4525 return; 4526 } 4527 4528 db_printf("buf at %p\n", bp); 4529 db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n", 4530 (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags, 4531 PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS); 4532 db_printf( 4533 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 4534 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, " 4535 "b_dep = %p\n", 4536 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 4537 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 4538 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first); 4539 if (bp->b_npages) { 4540 int i; 4541 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 4542 for (i = 0; i < bp->b_npages; i++) { 4543 vm_page_t m; 4544 m = bp->b_pages[i]; 4545 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 4546 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 4547 if ((i + 1) < bp->b_npages) 4548 db_printf(","); 4549 } 4550 db_printf("\n"); 4551 } 4552 db_printf(" "); 4553 BUF_LOCKPRINTINFO(bp); 4554} 4555 4556DB_SHOW_COMMAND(lockedbufs, lockedbufs) 4557{ 4558 struct buf *bp; 4559 int i; 4560 4561 for (i = 0; i < nbuf; i++) { 4562 bp = &buf[i]; 4563 if (BUF_ISLOCKED(bp)) { 4564 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4565 db_printf("\n"); 4566 } 4567 } 4568} 4569 4570DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 4571{ 4572 struct vnode *vp; 4573 struct buf *bp; 4574 4575 if (!have_addr) { 4576 db_printf("usage: show vnodebufs <addr>\n"); 4577 return; 4578 } 4579 vp = (struct vnode *)addr; 4580 db_printf("Clean buffers:\n"); 4581 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 4582 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4583 db_printf("\n"); 4584 } 4585 db_printf("Dirty buffers:\n"); 4586 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 4587 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4588 db_printf("\n"); 4589 } 4590} 4591 4592DB_COMMAND(countfreebufs, db_coundfreebufs) 4593{ 4594 struct buf *bp; 4595 int i, used = 0, nfree = 0; 4596 4597 if (have_addr) { 4598 db_printf("usage: countfreebufs\n"); 4599 return; 4600 } 4601 4602 for (i = 0; i < nbuf; i++) { 4603 bp = &buf[i]; 4604 if ((bp->b_flags & B_INFREECNT) != 0) 4605 nfree++; 4606 else 4607 used++; 4608 } 4609 4610 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 4611 nfree + used); 4612 db_printf("numfreebuffers is %d\n", numfreebuffers); 4613} 4614#endif /* DDB */ 4615