vfs_bio.c revision 270157
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: stable/10/sys/kern/vfs_bio.c 270157 2014-08-18 22:53:48Z mckusick $"); 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_swap.h" 81 82static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer"); 83 84struct bio_ops bioops; /* I/O operation notification */ 85 86struct buf_ops buf_ops_bio = { 87 .bop_name = "buf_ops_bio", 88 .bop_write = bufwrite, 89 .bop_strategy = bufstrategy, 90 .bop_sync = bufsync, 91 .bop_bdflush = bufbdflush, 92}; 93 94/* 95 * XXX buf is global because kern_shutdown.c and ffs_checkoverlap has 96 * carnal knowledge of buffers. This knowledge should be moved to vfs_bio.c. 97 */ 98struct buf *buf; /* buffer header pool */ 99caddr_t unmapped_buf; 100 101/* Used below and for softdep flushing threads in ufs/ffs/ffs_softdep.c */ 102struct 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(int); 117static int flushbufqueues(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 rwlock_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 volatile 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/* 355 * bqlock: 356 * 357 * Return the appropriate queue lock based on the index. 358 */ 359static inline struct mtx * 360bqlock(int qindex) 361{ 362 363 if (qindex == QUEUE_DIRTY) 364 return (struct mtx *)(&bqdirty); 365 return (struct mtx *)(&bqclean); 366} 367 368/* 369 * bdirtywakeup: 370 * 371 * Wakeup any bwillwrite() waiters. 372 */ 373static void 374bdirtywakeup(void) 375{ 376 mtx_lock(&bdirtylock); 377 if (bdirtywait) { 378 bdirtywait = 0; 379 wakeup(&bdirtywait); 380 } 381 mtx_unlock(&bdirtylock); 382} 383 384/* 385 * bdirtysub: 386 * 387 * Decrement the numdirtybuffers count by one and wakeup any 388 * threads blocked in bwillwrite(). 389 */ 390static void 391bdirtysub(void) 392{ 393 394 if (atomic_fetchadd_int(&numdirtybuffers, -1) == 395 (lodirtybuffers + hidirtybuffers) / 2) 396 bdirtywakeup(); 397} 398 399/* 400 * bdirtyadd: 401 * 402 * Increment the numdirtybuffers count by one and wakeup the buf 403 * daemon if needed. 404 */ 405static void 406bdirtyadd(void) 407{ 408 409 /* 410 * Only do the wakeup once as we cross the boundary. The 411 * buf daemon will keep running until the condition clears. 412 */ 413 if (atomic_fetchadd_int(&numdirtybuffers, 1) == 414 (lodirtybuffers + hidirtybuffers) / 2) 415 bd_wakeup(); 416} 417 418/* 419 * bufspacewakeup: 420 * 421 * Called when buffer space is potentially available for recovery. 422 * getnewbuf() will block on this flag when it is unable to free 423 * sufficient buffer space. Buffer space becomes recoverable when 424 * bp's get placed back in the queues. 425 */ 426 427static __inline void 428bufspacewakeup(void) 429{ 430 int need_wakeup, on; 431 432 /* 433 * If someone is waiting for BUF space, wake them up. Even 434 * though we haven't freed the kva space yet, the waiting 435 * process will be able to now. 436 */ 437 rw_rlock(&nblock); 438 for (;;) { 439 need_wakeup = 0; 440 on = needsbuffer; 441 if ((on & VFS_BIO_NEED_BUFSPACE) == 0) 442 break; 443 need_wakeup = 1; 444 if (atomic_cmpset_rel_int(&needsbuffer, on, 445 on & ~VFS_BIO_NEED_BUFSPACE)) 446 break; 447 } 448 if (need_wakeup) 449 wakeup(__DEVOLATILE(void *, &needsbuffer)); 450 rw_runlock(&nblock); 451} 452 453/* 454 * runningwakeup: 455 * 456 * Wake up processes that are waiting on asynchronous writes to fall 457 * below lorunningspace. 458 */ 459static void 460runningwakeup(void) 461{ 462 463 mtx_lock(&rbreqlock); 464 if (runningbufreq) { 465 runningbufreq = 0; 466 wakeup(&runningbufreq); 467 } 468 mtx_unlock(&rbreqlock); 469} 470 471/* 472 * runningbufwakeup: 473 * 474 * Decrement the outstanding write count according. 475 */ 476void 477runningbufwakeup(struct buf *bp) 478{ 479 long space, bspace; 480 481 bspace = bp->b_runningbufspace; 482 if (bspace == 0) 483 return; 484 space = atomic_fetchadd_long(&runningbufspace, -bspace); 485 KASSERT(space >= bspace, ("runningbufspace underflow %ld %ld", 486 space, bspace)); 487 bp->b_runningbufspace = 0; 488 /* 489 * Only acquire the lock and wakeup on the transition from exceeding 490 * the threshold to falling below it. 491 */ 492 if (space < lorunningspace) 493 return; 494 if (space - bspace > lorunningspace) 495 return; 496 runningwakeup(); 497} 498 499/* 500 * bufcountadd: 501 * 502 * Called when a buffer has been added to one of the free queues to 503 * account for the buffer and to wakeup anyone waiting for free buffers. 504 * This typically occurs when large amounts of metadata are being handled 505 * by the buffer cache ( else buffer space runs out first, usually ). 506 */ 507static __inline void 508bufcountadd(struct buf *bp) 509{ 510 int mask, need_wakeup, old, on; 511 512 KASSERT((bp->b_flags & B_INFREECNT) == 0, 513 ("buf %p already counted as free", bp)); 514 bp->b_flags |= B_INFREECNT; 515 old = atomic_fetchadd_int(&numfreebuffers, 1); 516 KASSERT(old >= 0 && old < nbuf, 517 ("numfreebuffers climbed to %d", old + 1)); 518 mask = VFS_BIO_NEED_ANY; 519 if (numfreebuffers >= hifreebuffers) 520 mask |= VFS_BIO_NEED_FREE; 521 rw_rlock(&nblock); 522 for (;;) { 523 need_wakeup = 0; 524 on = needsbuffer; 525 if (on == 0) 526 break; 527 need_wakeup = 1; 528 if (atomic_cmpset_rel_int(&needsbuffer, on, on & ~mask)) 529 break; 530 } 531 if (need_wakeup) 532 wakeup(__DEVOLATILE(void *, &needsbuffer)); 533 rw_runlock(&nblock); 534} 535 536/* 537 * bufcountsub: 538 * 539 * Decrement the numfreebuffers count as needed. 540 */ 541static void 542bufcountsub(struct buf *bp) 543{ 544 int old; 545 546 /* 547 * Fixup numfreebuffers count. If the buffer is invalid or not 548 * delayed-write, the buffer was free and we must decrement 549 * numfreebuffers. 550 */ 551 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { 552 KASSERT((bp->b_flags & B_INFREECNT) != 0, 553 ("buf %p not counted in numfreebuffers", bp)); 554 bp->b_flags &= ~B_INFREECNT; 555 old = atomic_fetchadd_int(&numfreebuffers, -1); 556 KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1)); 557 } 558} 559 560/* 561 * waitrunningbufspace() 562 * 563 * runningbufspace is a measure of the amount of I/O currently 564 * running. This routine is used in async-write situations to 565 * prevent creating huge backups of pending writes to a device. 566 * Only asynchronous writes are governed by this function. 567 * 568 * This does NOT turn an async write into a sync write. It waits 569 * for earlier writes to complete and generally returns before the 570 * caller's write has reached the device. 571 */ 572void 573waitrunningbufspace(void) 574{ 575 576 mtx_lock(&rbreqlock); 577 while (runningbufspace > hirunningspace) { 578 runningbufreq = 1; 579 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 580 } 581 mtx_unlock(&rbreqlock); 582} 583 584 585/* 586 * vfs_buf_test_cache: 587 * 588 * Called when a buffer is extended. This function clears the B_CACHE 589 * bit if the newly extended portion of the buffer does not contain 590 * valid data. 591 */ 592static __inline 593void 594vfs_buf_test_cache(struct buf *bp, 595 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 596 vm_page_t m) 597{ 598 599 VM_OBJECT_ASSERT_LOCKED(m->object); 600 if (bp->b_flags & B_CACHE) { 601 int base = (foff + off) & PAGE_MASK; 602 if (vm_page_is_valid(m, base, size) == 0) 603 bp->b_flags &= ~B_CACHE; 604 } 605} 606 607/* Wake up the buffer daemon if necessary */ 608static __inline void 609bd_wakeup(void) 610{ 611 612 mtx_lock(&bdlock); 613 if (bd_request == 0) { 614 bd_request = 1; 615 wakeup(&bd_request); 616 } 617 mtx_unlock(&bdlock); 618} 619 620/* 621 * bd_speedup - speedup the buffer cache flushing code 622 */ 623void 624bd_speedup(void) 625{ 626 int needwake; 627 628 mtx_lock(&bdlock); 629 needwake = 0; 630 if (bd_speedupreq == 0 || bd_request == 0) 631 needwake = 1; 632 bd_speedupreq = 1; 633 bd_request = 1; 634 if (needwake) 635 wakeup(&bd_request); 636 mtx_unlock(&bdlock); 637} 638 639#ifdef __i386__ 640#define TRANSIENT_DENOM 5 641#else 642#define TRANSIENT_DENOM 10 643#endif 644 645/* 646 * Calculating buffer cache scaling values and reserve space for buffer 647 * headers. This is called during low level kernel initialization and 648 * may be called more then once. We CANNOT write to the memory area 649 * being reserved at this time. 650 */ 651caddr_t 652kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 653{ 654 int tuned_nbuf; 655 long maxbuf, maxbuf_sz, buf_sz, biotmap_sz; 656 657 /* 658 * physmem_est is in pages. Convert it to kilobytes (assumes 659 * PAGE_SIZE is >= 1K) 660 */ 661 physmem_est = physmem_est * (PAGE_SIZE / 1024); 662 663 /* 664 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 665 * For the first 64MB of ram nominally allocate sufficient buffers to 666 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 667 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing 668 * the buffer cache we limit the eventual kva reservation to 669 * maxbcache bytes. 670 * 671 * factor represents the 1/4 x ram conversion. 672 */ 673 if (nbuf == 0) { 674 int factor = 4 * BKVASIZE / 1024; 675 676 nbuf = 50; 677 if (physmem_est > 4096) 678 nbuf += min((physmem_est - 4096) / factor, 679 65536 / factor); 680 if (physmem_est > 65536) 681 nbuf += min((physmem_est - 65536) * 2 / (factor * 5), 682 32 * 1024 * 1024 / (factor * 5)); 683 684 if (maxbcache && nbuf > maxbcache / BKVASIZE) 685 nbuf = maxbcache / BKVASIZE; 686 tuned_nbuf = 1; 687 } else 688 tuned_nbuf = 0; 689 690 /* XXX Avoid unsigned long overflows later on with maxbufspace. */ 691 maxbuf = (LONG_MAX / 3) / BKVASIZE; 692 if (nbuf > maxbuf) { 693 if (!tuned_nbuf) 694 printf("Warning: nbufs lowered from %d to %ld\n", nbuf, 695 maxbuf); 696 nbuf = maxbuf; 697 } 698 699 /* 700 * Ideal allocation size for the transient bio submap if 10% 701 * of the maximal space buffer map. This roughly corresponds 702 * to the amount of the buffer mapped for typical UFS load. 703 * 704 * Clip the buffer map to reserve space for the transient 705 * BIOs, if its extent is bigger than 90% (80% on i386) of the 706 * maximum buffer map extent on the platform. 707 * 708 * The fall-back to the maxbuf in case of maxbcache unset, 709 * allows to not trim the buffer KVA for the architectures 710 * with ample KVA space. 711 */ 712 if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) { 713 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE; 714 buf_sz = (long)nbuf * BKVASIZE; 715 if (buf_sz < maxbuf_sz / TRANSIENT_DENOM * 716 (TRANSIENT_DENOM - 1)) { 717 /* 718 * There is more KVA than memory. Do not 719 * adjust buffer map size, and assign the rest 720 * of maxbuf to transient map. 721 */ 722 biotmap_sz = maxbuf_sz - buf_sz; 723 } else { 724 /* 725 * Buffer map spans all KVA we could afford on 726 * this platform. Give 10% (20% on i386) of 727 * the buffer map to the transient bio map. 728 */ 729 biotmap_sz = buf_sz / TRANSIENT_DENOM; 730 buf_sz -= biotmap_sz; 731 } 732 if (biotmap_sz / INT_MAX > MAXPHYS) 733 bio_transient_maxcnt = INT_MAX; 734 else 735 bio_transient_maxcnt = biotmap_sz / MAXPHYS; 736 /* 737 * Artifically limit to 1024 simultaneous in-flight I/Os 738 * using the transient mapping. 739 */ 740 if (bio_transient_maxcnt > 1024) 741 bio_transient_maxcnt = 1024; 742 if (tuned_nbuf) 743 nbuf = buf_sz / BKVASIZE; 744 } 745 746 /* 747 * swbufs are used as temporary holders for I/O, such as paging I/O. 748 * We have no less then 16 and no more then 256. 749 */ 750 nswbuf = max(min(nbuf/4, 256), 16); 751#ifdef NSWBUF_MIN 752 if (nswbuf < NSWBUF_MIN) 753 nswbuf = NSWBUF_MIN; 754#endif 755 756 /* 757 * Reserve space for the buffer cache buffers 758 */ 759 swbuf = (void *)v; 760 v = (caddr_t)(swbuf + nswbuf); 761 buf = (void *)v; 762 v = (caddr_t)(buf + nbuf); 763 764 return(v); 765} 766 767/* Initialize the buffer subsystem. Called before use of any buffers. */ 768void 769bufinit(void) 770{ 771 struct buf *bp; 772 int i; 773 774 mtx_init(&bqclean, "bufq clean lock", NULL, MTX_DEF); 775 mtx_init(&bqdirty, "bufq dirty lock", NULL, MTX_DEF); 776 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 777 rw_init(&nblock, "needsbuffer lock"); 778 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 779 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF); 780 781 /* next, make a null set of free lists */ 782 for (i = 0; i < BUFFER_QUEUES; i++) 783 TAILQ_INIT(&bufqueues[i]); 784 785 /* finally, initialize each buffer header and stick on empty q */ 786 for (i = 0; i < nbuf; i++) { 787 bp = &buf[i]; 788 bzero(bp, sizeof *bp); 789 bp->b_flags = B_INVAL | B_INFREECNT; 790 bp->b_rcred = NOCRED; 791 bp->b_wcred = NOCRED; 792 bp->b_qindex = QUEUE_EMPTY; 793 bp->b_xflags = 0; 794 LIST_INIT(&bp->b_dep); 795 BUF_LOCKINIT(bp); 796 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 797#ifdef INVARIANTS 798 bq_len[QUEUE_EMPTY]++; 799#endif 800 } 801 802 /* 803 * maxbufspace is the absolute maximum amount of buffer space we are 804 * allowed to reserve in KVM and in real terms. The absolute maximum 805 * is nominally used by buf_daemon. hibufspace is the nominal maximum 806 * used by most other processes. The differential is required to 807 * ensure that buf_daemon is able to run when other processes might 808 * be blocked waiting for buffer space. 809 * 810 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 811 * this may result in KVM fragmentation which is not handled optimally 812 * by the system. 813 */ 814 maxbufspace = (long)nbuf * BKVASIZE; 815 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 816 lobufspace = hibufspace - MAXBSIZE; 817 818 /* 819 * Note: The 16 MiB upper limit for hirunningspace was chosen 820 * arbitrarily and may need further tuning. It corresponds to 821 * 128 outstanding write IO requests (if IO size is 128 KiB), 822 * which fits with many RAID controllers' tagged queuing limits. 823 * The lower 1 MiB limit is the historical upper limit for 824 * hirunningspace. 825 */ 826 hirunningspace = lmax(lmin(roundup(hibufspace / 64, MAXBSIZE), 827 16 * 1024 * 1024), 1024 * 1024); 828 lorunningspace = roundup((hirunningspace * 2) / 3, MAXBSIZE); 829 830/* 831 * Limit the amount of malloc memory since it is wired permanently into 832 * the kernel space. Even though this is accounted for in the buffer 833 * allocation, we don't want the malloced region to grow uncontrolled. 834 * The malloc scheme improves memory utilization significantly on average 835 * (small) directories. 836 */ 837 maxbufmallocspace = hibufspace / 20; 838 839/* 840 * Reduce the chance of a deadlock occuring by limiting the number 841 * of delayed-write dirty buffers we allow to stack up. 842 */ 843 hidirtybuffers = nbuf / 4 + 20; 844 dirtybufthresh = hidirtybuffers * 9 / 10; 845 numdirtybuffers = 0; 846/* 847 * To support extreme low-memory systems, make sure hidirtybuffers cannot 848 * eat up all available buffer space. This occurs when our minimum cannot 849 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 850 * BKVASIZE'd buffers. 851 */ 852 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 853 hidirtybuffers >>= 1; 854 } 855 lodirtybuffers = hidirtybuffers / 2; 856 857/* 858 * Try to keep the number of free buffers in the specified range, 859 * and give special processes (e.g. like buf_daemon) access to an 860 * emergency reserve. 861 */ 862 lofreebuffers = nbuf / 18 + 5; 863 hifreebuffers = 2 * lofreebuffers; 864 numfreebuffers = nbuf; 865 866 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ | 867 VM_ALLOC_NORMAL | VM_ALLOC_WIRED); 868 unmapped_buf = (caddr_t)kva_alloc(MAXPHYS); 869} 870 871#ifdef INVARIANTS 872static inline void 873vfs_buf_check_mapped(struct buf *bp) 874{ 875 876 KASSERT((bp->b_flags & B_UNMAPPED) == 0, 877 ("mapped buf %p %x", bp, bp->b_flags)); 878 KASSERT(bp->b_kvabase != unmapped_buf, 879 ("mapped buf: b_kvabase was not updated %p", bp)); 880 KASSERT(bp->b_data != unmapped_buf, 881 ("mapped buf: b_data was not updated %p", bp)); 882} 883 884static inline void 885vfs_buf_check_unmapped(struct buf *bp) 886{ 887 888 KASSERT((bp->b_flags & B_UNMAPPED) == B_UNMAPPED, 889 ("unmapped buf %p %x", bp, bp->b_flags)); 890 KASSERT(bp->b_kvabase == unmapped_buf, 891 ("unmapped buf: corrupted b_kvabase %p", bp)); 892 KASSERT(bp->b_data == unmapped_buf, 893 ("unmapped buf: corrupted b_data %p", bp)); 894} 895 896#define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp) 897#define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp) 898#else 899#define BUF_CHECK_MAPPED(bp) do {} while (0) 900#define BUF_CHECK_UNMAPPED(bp) do {} while (0) 901#endif 902 903static void 904bpmap_qenter(struct buf *bp) 905{ 906 907 BUF_CHECK_MAPPED(bp); 908 909 /* 910 * bp->b_data is relative to bp->b_offset, but 911 * bp->b_offset may be offset into the first page. 912 */ 913 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data); 914 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages); 915 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 916 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 917} 918 919/* 920 * bfreekva() - free the kva allocation for a buffer. 921 * 922 * Since this call frees up buffer space, we call bufspacewakeup(). 923 */ 924static void 925bfreekva(struct buf *bp) 926{ 927 928 if (bp->b_kvasize == 0) 929 return; 930 931 atomic_add_int(&buffreekvacnt, 1); 932 atomic_subtract_long(&bufspace, bp->b_kvasize); 933 if ((bp->b_flags & B_UNMAPPED) == 0) { 934 BUF_CHECK_MAPPED(bp); 935 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, 936 bp->b_kvasize); 937 } else { 938 BUF_CHECK_UNMAPPED(bp); 939 if ((bp->b_flags & B_KVAALLOC) != 0) { 940 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvaalloc, 941 bp->b_kvasize); 942 } 943 atomic_subtract_long(&unmapped_bufspace, bp->b_kvasize); 944 bp->b_flags &= ~(B_UNMAPPED | B_KVAALLOC); 945 } 946 bp->b_kvasize = 0; 947 bufspacewakeup(); 948} 949 950/* 951 * binsfree: 952 * 953 * Insert the buffer into the appropriate free list. 954 */ 955static void 956binsfree(struct buf *bp, int qindex) 957{ 958 struct mtx *olock, *nlock; 959 960 BUF_ASSERT_XLOCKED(bp); 961 962 olock = bqlock(bp->b_qindex); 963 nlock = bqlock(qindex); 964 mtx_lock(olock); 965 /* Handle delayed bremfree() processing. */ 966 if (bp->b_flags & B_REMFREE) 967 bremfreel(bp); 968 969 if (bp->b_qindex != QUEUE_NONE) 970 panic("binsfree: free buffer onto another queue???"); 971 972 bp->b_qindex = qindex; 973 if (olock != nlock) { 974 mtx_unlock(olock); 975 mtx_lock(nlock); 976 } 977 if (bp->b_flags & B_AGE) 978 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 979 else 980 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 981#ifdef INVARIANTS 982 bq_len[bp->b_qindex]++; 983#endif 984 mtx_unlock(nlock); 985 986 /* 987 * Something we can maybe free or reuse. 988 */ 989 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 990 bufspacewakeup(); 991 992 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI)) 993 bufcountadd(bp); 994} 995 996/* 997 * bremfree: 998 * 999 * Mark the buffer for removal from the appropriate free list. 1000 * 1001 */ 1002void 1003bremfree(struct buf *bp) 1004{ 1005 1006 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1007 KASSERT((bp->b_flags & B_REMFREE) == 0, 1008 ("bremfree: buffer %p already marked for delayed removal.", bp)); 1009 KASSERT(bp->b_qindex != QUEUE_NONE, 1010 ("bremfree: buffer %p not on a queue.", bp)); 1011 BUF_ASSERT_XLOCKED(bp); 1012 1013 bp->b_flags |= B_REMFREE; 1014 bufcountsub(bp); 1015} 1016 1017/* 1018 * bremfreef: 1019 * 1020 * Force an immediate removal from a free list. Used only in nfs when 1021 * it abuses the b_freelist pointer. 1022 */ 1023void 1024bremfreef(struct buf *bp) 1025{ 1026 struct mtx *qlock; 1027 1028 qlock = bqlock(bp->b_qindex); 1029 mtx_lock(qlock); 1030 bremfreel(bp); 1031 mtx_unlock(qlock); 1032} 1033 1034/* 1035 * bremfreel: 1036 * 1037 * Removes a buffer from the free list, must be called with the 1038 * correct qlock held. 1039 */ 1040static void 1041bremfreel(struct buf *bp) 1042{ 1043 1044 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X", 1045 bp, bp->b_vp, bp->b_flags); 1046 KASSERT(bp->b_qindex != QUEUE_NONE, 1047 ("bremfreel: buffer %p not on a queue.", bp)); 1048 BUF_ASSERT_XLOCKED(bp); 1049 mtx_assert(bqlock(bp->b_qindex), MA_OWNED); 1050 1051 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 1052#ifdef INVARIANTS 1053 KASSERT(bq_len[bp->b_qindex] >= 1, ("queue %d underflow", 1054 bp->b_qindex)); 1055 bq_len[bp->b_qindex]--; 1056#endif 1057 bp->b_qindex = QUEUE_NONE; 1058 /* 1059 * If this was a delayed bremfree() we only need to remove the buffer 1060 * from the queue and return the stats are already done. 1061 */ 1062 if (bp->b_flags & B_REMFREE) { 1063 bp->b_flags &= ~B_REMFREE; 1064 return; 1065 } 1066 bufcountsub(bp); 1067} 1068 1069/* 1070 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 1071 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 1072 * the buffer is valid and we do not have to do anything. 1073 */ 1074void 1075breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, 1076 int cnt, struct ucred * cred) 1077{ 1078 struct buf *rabp; 1079 int i; 1080 1081 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 1082 if (inmem(vp, *rablkno)) 1083 continue; 1084 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 1085 1086 if ((rabp->b_flags & B_CACHE) == 0) { 1087 if (!TD_IS_IDLETHREAD(curthread)) 1088 curthread->td_ru.ru_inblock++; 1089 rabp->b_flags |= B_ASYNC; 1090 rabp->b_flags &= ~B_INVAL; 1091 rabp->b_ioflags &= ~BIO_ERROR; 1092 rabp->b_iocmd = BIO_READ; 1093 if (rabp->b_rcred == NOCRED && cred != NOCRED) 1094 rabp->b_rcred = crhold(cred); 1095 vfs_busy_pages(rabp, 0); 1096 BUF_KERNPROC(rabp); 1097 rabp->b_iooffset = dbtob(rabp->b_blkno); 1098 bstrategy(rabp); 1099 } else { 1100 brelse(rabp); 1101 } 1102 } 1103} 1104 1105/* 1106 * Entry point for bread() and breadn() via #defines in sys/buf.h. 1107 * 1108 * Get a buffer with the specified data. Look in the cache first. We 1109 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 1110 * is set, the buffer is valid and we do not have to do anything, see 1111 * getblk(). Also starts asynchronous I/O on read-ahead blocks. 1112 */ 1113int 1114breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno, 1115 int *rabsize, int cnt, struct ucred *cred, int flags, struct buf **bpp) 1116{ 1117 struct buf *bp; 1118 int rv = 0, readwait = 0; 1119 1120 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 1121 /* 1122 * Can only return NULL if GB_LOCK_NOWAIT flag is specified. 1123 */ 1124 *bpp = bp = getblk(vp, blkno, size, 0, 0, flags); 1125 if (bp == NULL) 1126 return (EBUSY); 1127 1128 /* if not found in cache, do some I/O */ 1129 if ((bp->b_flags & B_CACHE) == 0) { 1130 if (!TD_IS_IDLETHREAD(curthread)) 1131 curthread->td_ru.ru_inblock++; 1132 bp->b_iocmd = BIO_READ; 1133 bp->b_flags &= ~B_INVAL; 1134 bp->b_ioflags &= ~BIO_ERROR; 1135 if (bp->b_rcred == NOCRED && cred != NOCRED) 1136 bp->b_rcred = crhold(cred); 1137 vfs_busy_pages(bp, 0); 1138 bp->b_iooffset = dbtob(bp->b_blkno); 1139 bstrategy(bp); 1140 ++readwait; 1141 } 1142 1143 breada(vp, rablkno, rabsize, cnt, cred); 1144 1145 if (readwait) { 1146 rv = bufwait(bp); 1147 } 1148 return (rv); 1149} 1150 1151/* 1152 * Write, release buffer on completion. (Done by iodone 1153 * if async). Do not bother writing anything if the buffer 1154 * is invalid. 1155 * 1156 * Note that we set B_CACHE here, indicating that buffer is 1157 * fully valid and thus cacheable. This is true even of NFS 1158 * now so we set it generally. This could be set either here 1159 * or in biodone() since the I/O is synchronous. We put it 1160 * here. 1161 */ 1162int 1163bufwrite(struct buf *bp) 1164{ 1165 int oldflags; 1166 struct vnode *vp; 1167 long space; 1168 int vp_md; 1169 1170 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1171 if (bp->b_flags & B_INVAL) { 1172 brelse(bp); 1173 return (0); 1174 } 1175 1176 if (bp->b_flags & B_BARRIER) 1177 barrierwrites++; 1178 1179 oldflags = bp->b_flags; 1180 1181 BUF_ASSERT_HELD(bp); 1182 1183 if (bp->b_pin_count > 0) 1184 bunpin_wait(bp); 1185 1186 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 1187 ("FFS background buffer should not get here %p", bp)); 1188 1189 vp = bp->b_vp; 1190 if (vp) 1191 vp_md = vp->v_vflag & VV_MD; 1192 else 1193 vp_md = 0; 1194 1195 /* 1196 * Mark the buffer clean. Increment the bufobj write count 1197 * before bundirty() call, to prevent other thread from seeing 1198 * empty dirty list and zero counter for writes in progress, 1199 * falsely indicating that the bufobj is clean. 1200 */ 1201 bufobj_wref(bp->b_bufobj); 1202 bundirty(bp); 1203 1204 bp->b_flags &= ~B_DONE; 1205 bp->b_ioflags &= ~BIO_ERROR; 1206 bp->b_flags |= B_CACHE; 1207 bp->b_iocmd = BIO_WRITE; 1208 1209 vfs_busy_pages(bp, 1); 1210 1211 /* 1212 * Normal bwrites pipeline writes 1213 */ 1214 bp->b_runningbufspace = bp->b_bufsize; 1215 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace); 1216 1217 if (!TD_IS_IDLETHREAD(curthread)) 1218 curthread->td_ru.ru_oublock++; 1219 if (oldflags & B_ASYNC) 1220 BUF_KERNPROC(bp); 1221 bp->b_iooffset = dbtob(bp->b_blkno); 1222 bstrategy(bp); 1223 1224 if ((oldflags & B_ASYNC) == 0) { 1225 int rtval = bufwait(bp); 1226 brelse(bp); 1227 return (rtval); 1228 } else if (space > hirunningspace) { 1229 /* 1230 * don't allow the async write to saturate the I/O 1231 * system. We will not deadlock here because 1232 * we are blocking waiting for I/O that is already in-progress 1233 * to complete. We do not block here if it is the update 1234 * or syncer daemon trying to clean up as that can lead 1235 * to deadlock. 1236 */ 1237 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 1238 waitrunningbufspace(); 1239 } 1240 1241 return (0); 1242} 1243 1244void 1245bufbdflush(struct bufobj *bo, struct buf *bp) 1246{ 1247 struct buf *nbp; 1248 1249 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 1250 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 1251 altbufferflushes++; 1252 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 1253 BO_LOCK(bo); 1254 /* 1255 * Try to find a buffer to flush. 1256 */ 1257 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 1258 if ((nbp->b_vflags & BV_BKGRDINPROG) || 1259 BUF_LOCK(nbp, 1260 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 1261 continue; 1262 if (bp == nbp) 1263 panic("bdwrite: found ourselves"); 1264 BO_UNLOCK(bo); 1265 /* Don't countdeps with the bo lock held. */ 1266 if (buf_countdeps(nbp, 0)) { 1267 BO_LOCK(bo); 1268 BUF_UNLOCK(nbp); 1269 continue; 1270 } 1271 if (nbp->b_flags & B_CLUSTEROK) { 1272 vfs_bio_awrite(nbp); 1273 } else { 1274 bremfree(nbp); 1275 bawrite(nbp); 1276 } 1277 dirtybufferflushes++; 1278 break; 1279 } 1280 if (nbp == NULL) 1281 BO_UNLOCK(bo); 1282 } 1283} 1284 1285/* 1286 * Delayed write. (Buffer is marked dirty). Do not bother writing 1287 * anything if the buffer is marked invalid. 1288 * 1289 * Note that since the buffer must be completely valid, we can safely 1290 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 1291 * biodone() in order to prevent getblk from writing the buffer 1292 * out synchronously. 1293 */ 1294void 1295bdwrite(struct buf *bp) 1296{ 1297 struct thread *td = curthread; 1298 struct vnode *vp; 1299 struct bufobj *bo; 1300 1301 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1302 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1303 KASSERT((bp->b_flags & B_BARRIER) == 0, 1304 ("Barrier request in delayed write %p", bp)); 1305 BUF_ASSERT_HELD(bp); 1306 1307 if (bp->b_flags & B_INVAL) { 1308 brelse(bp); 1309 return; 1310 } 1311 1312 /* 1313 * If we have too many dirty buffers, don't create any more. 1314 * If we are wildly over our limit, then force a complete 1315 * cleanup. Otherwise, just keep the situation from getting 1316 * out of control. Note that we have to avoid a recursive 1317 * disaster and not try to clean up after our own cleanup! 1318 */ 1319 vp = bp->b_vp; 1320 bo = bp->b_bufobj; 1321 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 1322 td->td_pflags |= TDP_INBDFLUSH; 1323 BO_BDFLUSH(bo, bp); 1324 td->td_pflags &= ~TDP_INBDFLUSH; 1325 } else 1326 recursiveflushes++; 1327 1328 bdirty(bp); 1329 /* 1330 * Set B_CACHE, indicating that the buffer is fully valid. This is 1331 * true even of NFS now. 1332 */ 1333 bp->b_flags |= B_CACHE; 1334 1335 /* 1336 * This bmap keeps the system from needing to do the bmap later, 1337 * perhaps when the system is attempting to do a sync. Since it 1338 * is likely that the indirect block -- or whatever other datastructure 1339 * that the filesystem needs is still in memory now, it is a good 1340 * thing to do this. Note also, that if the pageout daemon is 1341 * requesting a sync -- there might not be enough memory to do 1342 * the bmap then... So, this is important to do. 1343 */ 1344 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 1345 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 1346 } 1347 1348 /* 1349 * Set the *dirty* buffer range based upon the VM system dirty 1350 * pages. 1351 * 1352 * Mark the buffer pages as clean. We need to do this here to 1353 * satisfy the vnode_pager and the pageout daemon, so that it 1354 * thinks that the pages have been "cleaned". Note that since 1355 * the pages are in a delayed write buffer -- the VFS layer 1356 * "will" see that the pages get written out on the next sync, 1357 * or perhaps the cluster will be completed. 1358 */ 1359 vfs_clean_pages_dirty_buf(bp); 1360 bqrelse(bp); 1361 1362 /* 1363 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 1364 * due to the softdep code. 1365 */ 1366} 1367 1368/* 1369 * bdirty: 1370 * 1371 * Turn buffer into delayed write request. We must clear BIO_READ and 1372 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 1373 * itself to properly update it in the dirty/clean lists. We mark it 1374 * B_DONE to ensure that any asynchronization of the buffer properly 1375 * clears B_DONE ( else a panic will occur later ). 1376 * 1377 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 1378 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 1379 * should only be called if the buffer is known-good. 1380 * 1381 * Since the buffer is not on a queue, we do not update the numfreebuffers 1382 * count. 1383 * 1384 * The buffer must be on QUEUE_NONE. 1385 */ 1386void 1387bdirty(struct buf *bp) 1388{ 1389 1390 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 1391 bp, bp->b_vp, bp->b_flags); 1392 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1393 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1394 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1395 BUF_ASSERT_HELD(bp); 1396 bp->b_flags &= ~(B_RELBUF); 1397 bp->b_iocmd = BIO_WRITE; 1398 1399 if ((bp->b_flags & B_DELWRI) == 0) { 1400 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 1401 reassignbuf(bp); 1402 bdirtyadd(); 1403 } 1404} 1405 1406/* 1407 * bundirty: 1408 * 1409 * Clear B_DELWRI for buffer. 1410 * 1411 * Since the buffer is not on a queue, we do not update the numfreebuffers 1412 * count. 1413 * 1414 * The buffer must be on QUEUE_NONE. 1415 */ 1416 1417void 1418bundirty(struct buf *bp) 1419{ 1420 1421 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1422 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1423 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1424 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1425 BUF_ASSERT_HELD(bp); 1426 1427 if (bp->b_flags & B_DELWRI) { 1428 bp->b_flags &= ~B_DELWRI; 1429 reassignbuf(bp); 1430 bdirtysub(); 1431 } 1432 /* 1433 * Since it is now being written, we can clear its deferred write flag. 1434 */ 1435 bp->b_flags &= ~B_DEFERRED; 1436} 1437 1438/* 1439 * bawrite: 1440 * 1441 * Asynchronous write. Start output on a buffer, but do not wait for 1442 * it to complete. The buffer is released when the output completes. 1443 * 1444 * bwrite() ( or the VOP routine anyway ) is responsible for handling 1445 * B_INVAL buffers. Not us. 1446 */ 1447void 1448bawrite(struct buf *bp) 1449{ 1450 1451 bp->b_flags |= B_ASYNC; 1452 (void) bwrite(bp); 1453} 1454 1455/* 1456 * babarrierwrite: 1457 * 1458 * Asynchronous barrier write. Start output on a buffer, but do not 1459 * wait for it to complete. Place a write barrier after this write so 1460 * that this buffer and all buffers written before it are committed to 1461 * the disk before any buffers written after this write are committed 1462 * to the disk. The buffer is released when the output completes. 1463 */ 1464void 1465babarrierwrite(struct buf *bp) 1466{ 1467 1468 bp->b_flags |= B_ASYNC | B_BARRIER; 1469 (void) bwrite(bp); 1470} 1471 1472/* 1473 * bbarrierwrite: 1474 * 1475 * Synchronous barrier write. Start output on a buffer and wait for 1476 * it to complete. Place a write barrier after this write so that 1477 * this buffer and all buffers written before it are committed to 1478 * the disk before any buffers written after this write are committed 1479 * to the disk. The buffer is released when the output completes. 1480 */ 1481int 1482bbarrierwrite(struct buf *bp) 1483{ 1484 1485 bp->b_flags |= B_BARRIER; 1486 return (bwrite(bp)); 1487} 1488 1489/* 1490 * bwillwrite: 1491 * 1492 * Called prior to the locking of any vnodes when we are expecting to 1493 * write. We do not want to starve the buffer cache with too many 1494 * dirty buffers so we block here. By blocking prior to the locking 1495 * of any vnodes we attempt to avoid the situation where a locked vnode 1496 * prevents the various system daemons from flushing related buffers. 1497 */ 1498void 1499bwillwrite(void) 1500{ 1501 1502 if (numdirtybuffers >= hidirtybuffers) { 1503 mtx_lock(&bdirtylock); 1504 while (numdirtybuffers >= hidirtybuffers) { 1505 bdirtywait = 1; 1506 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4), 1507 "flswai", 0); 1508 } 1509 mtx_unlock(&bdirtylock); 1510 } 1511} 1512 1513/* 1514 * Return true if we have too many dirty buffers. 1515 */ 1516int 1517buf_dirty_count_severe(void) 1518{ 1519 1520 return(numdirtybuffers >= hidirtybuffers); 1521} 1522 1523static __noinline int 1524buf_vm_page_count_severe(void) 1525{ 1526 1527 KFAIL_POINT_CODE(DEBUG_FP, buf_pressure, return 1); 1528 1529 return vm_page_count_severe(); 1530} 1531 1532/* 1533 * brelse: 1534 * 1535 * Release a busy buffer and, if requested, free its resources. The 1536 * buffer will be stashed in the appropriate bufqueue[] allowing it 1537 * to be accessed later as a cache entity or reused for other purposes. 1538 */ 1539void 1540brelse(struct buf *bp) 1541{ 1542 int qindex; 1543 1544 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 1545 bp, bp->b_vp, bp->b_flags); 1546 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1547 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1548 1549 if (BUF_LOCKRECURSED(bp)) { 1550 /* 1551 * Do not process, in particular, do not handle the 1552 * B_INVAL/B_RELBUF and do not release to free list. 1553 */ 1554 BUF_UNLOCK(bp); 1555 return; 1556 } 1557 1558 if (bp->b_flags & B_MANAGED) { 1559 bqrelse(bp); 1560 return; 1561 } 1562 1563 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 1564 bp->b_error == EIO && !(bp->b_flags & B_INVAL)) { 1565 /* 1566 * Failed write, redirty. Must clear BIO_ERROR to prevent 1567 * pages from being scrapped. If the error is anything 1568 * other than an I/O error (EIO), assume that retrying 1569 * is futile. 1570 */ 1571 bp->b_ioflags &= ~BIO_ERROR; 1572 bdirty(bp); 1573 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 1574 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 1575 /* 1576 * Either a failed I/O or we were asked to free or not 1577 * cache the buffer. 1578 */ 1579 bp->b_flags |= B_INVAL; 1580 if (!LIST_EMPTY(&bp->b_dep)) 1581 buf_deallocate(bp); 1582 if (bp->b_flags & B_DELWRI) 1583 bdirtysub(); 1584 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1585 if ((bp->b_flags & B_VMIO) == 0) { 1586 if (bp->b_bufsize) 1587 allocbuf(bp, 0); 1588 if (bp->b_vp) 1589 brelvp(bp); 1590 } 1591 } 1592 1593 /* 1594 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1595 * is called with B_DELWRI set, the underlying pages may wind up 1596 * getting freed causing a previous write (bdwrite()) to get 'lost' 1597 * because pages associated with a B_DELWRI bp are marked clean. 1598 * 1599 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1600 * if B_DELWRI is set. 1601 * 1602 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1603 * on pages to return pages to the VM page queues. 1604 */ 1605 if (bp->b_flags & B_DELWRI) 1606 bp->b_flags &= ~B_RELBUF; 1607 else if (buf_vm_page_count_severe()) { 1608 /* 1609 * BKGRDINPROG can only be set with the buf and bufobj 1610 * locks both held. We tolerate a race to clear it here. 1611 */ 1612 if (!(bp->b_vflags & BV_BKGRDINPROG)) 1613 bp->b_flags |= B_RELBUF; 1614 } 1615 1616 /* 1617 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1618 * constituted, not even NFS buffers now. Two flags effect this. If 1619 * B_INVAL, the struct buf is invalidated but the VM object is kept 1620 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1621 * 1622 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 1623 * invalidated. BIO_ERROR cannot be set for a failed write unless the 1624 * buffer is also B_INVAL because it hits the re-dirtying code above. 1625 * 1626 * Normally we can do this whether a buffer is B_DELWRI or not. If 1627 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1628 * the commit state and we cannot afford to lose the buffer. If the 1629 * buffer has a background write in progress, we need to keep it 1630 * around to prevent it from being reconstituted and starting a second 1631 * background write. 1632 */ 1633 if ((bp->b_flags & B_VMIO) 1634 && !(bp->b_vp->v_mount != NULL && 1635 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 1636 !vn_isdisk(bp->b_vp, NULL) && 1637 (bp->b_flags & B_DELWRI)) 1638 ) { 1639 1640 int i, j, resid; 1641 vm_page_t m; 1642 off_t foff; 1643 vm_pindex_t poff; 1644 vm_object_t obj; 1645 1646 obj = bp->b_bufobj->bo_object; 1647 1648 /* 1649 * Get the base offset and length of the buffer. Note that 1650 * in the VMIO case if the buffer block size is not 1651 * page-aligned then b_data pointer may not be page-aligned. 1652 * But our b_pages[] array *IS* page aligned. 1653 * 1654 * block sizes less then DEV_BSIZE (usually 512) are not 1655 * supported due to the page granularity bits (m->valid, 1656 * m->dirty, etc...). 1657 * 1658 * See man buf(9) for more information 1659 */ 1660 resid = bp->b_bufsize; 1661 foff = bp->b_offset; 1662 for (i = 0; i < bp->b_npages; i++) { 1663 int had_bogus = 0; 1664 1665 m = bp->b_pages[i]; 1666 1667 /* 1668 * If we hit a bogus page, fixup *all* the bogus pages 1669 * now. 1670 */ 1671 if (m == bogus_page) { 1672 poff = OFF_TO_IDX(bp->b_offset); 1673 had_bogus = 1; 1674 1675 VM_OBJECT_RLOCK(obj); 1676 for (j = i; j < bp->b_npages; j++) { 1677 vm_page_t mtmp; 1678 mtmp = bp->b_pages[j]; 1679 if (mtmp == bogus_page) { 1680 mtmp = vm_page_lookup(obj, poff + j); 1681 if (!mtmp) { 1682 panic("brelse: page missing\n"); 1683 } 1684 bp->b_pages[j] = mtmp; 1685 } 1686 } 1687 VM_OBJECT_RUNLOCK(obj); 1688 1689 if ((bp->b_flags & (B_INVAL | B_UNMAPPED)) == 0) { 1690 BUF_CHECK_MAPPED(bp); 1691 pmap_qenter( 1692 trunc_page((vm_offset_t)bp->b_data), 1693 bp->b_pages, bp->b_npages); 1694 } 1695 m = bp->b_pages[i]; 1696 } 1697 if ((bp->b_flags & B_NOCACHE) || 1698 (bp->b_ioflags & BIO_ERROR && 1699 bp->b_iocmd == BIO_READ)) { 1700 int poffset = foff & PAGE_MASK; 1701 int presid = resid > (PAGE_SIZE - poffset) ? 1702 (PAGE_SIZE - poffset) : resid; 1703 1704 KASSERT(presid >= 0, ("brelse: extra page")); 1705 VM_OBJECT_WLOCK(obj); 1706 while (vm_page_xbusied(m)) { 1707 vm_page_lock(m); 1708 VM_OBJECT_WUNLOCK(obj); 1709 vm_page_busy_sleep(m, "mbncsh"); 1710 VM_OBJECT_WLOCK(obj); 1711 } 1712 if (pmap_page_wired_mappings(m) == 0) 1713 vm_page_set_invalid(m, poffset, presid); 1714 VM_OBJECT_WUNLOCK(obj); 1715 if (had_bogus) 1716 printf("avoided corruption bug in bogus_page/brelse code\n"); 1717 } 1718 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1719 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1720 } 1721 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1722 vfs_vmio_release(bp); 1723 1724 } else if (bp->b_flags & B_VMIO) { 1725 1726 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1727 vfs_vmio_release(bp); 1728 } 1729 1730 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) { 1731 if (bp->b_bufsize != 0) 1732 allocbuf(bp, 0); 1733 if (bp->b_vp != NULL) 1734 brelvp(bp); 1735 } 1736 1737 /* 1738 * If the buffer has junk contents signal it and eventually 1739 * clean up B_DELWRI and diassociate the vnode so that gbincore() 1740 * doesn't find it. 1741 */ 1742 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 1743 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 1744 bp->b_flags |= B_INVAL; 1745 if (bp->b_flags & B_INVAL) { 1746 if (bp->b_flags & B_DELWRI) 1747 bundirty(bp); 1748 if (bp->b_vp) 1749 brelvp(bp); 1750 } 1751 1752 /* buffers with no memory */ 1753 if (bp->b_bufsize == 0) { 1754 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1755 if (bp->b_vflags & BV_BKGRDINPROG) 1756 panic("losing buffer 1"); 1757 if (bp->b_kvasize) 1758 qindex = QUEUE_EMPTYKVA; 1759 else 1760 qindex = QUEUE_EMPTY; 1761 bp->b_flags |= B_AGE; 1762 /* buffers with junk contents */ 1763 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 1764 (bp->b_ioflags & BIO_ERROR)) { 1765 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1766 if (bp->b_vflags & BV_BKGRDINPROG) 1767 panic("losing buffer 2"); 1768 qindex = QUEUE_CLEAN; 1769 bp->b_flags |= B_AGE; 1770 /* remaining buffers */ 1771 } else if (bp->b_flags & B_DELWRI) 1772 qindex = QUEUE_DIRTY; 1773 else 1774 qindex = QUEUE_CLEAN; 1775 1776 binsfree(bp, qindex); 1777 1778 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 1779 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1780 panic("brelse: not dirty"); 1781 /* unlock */ 1782 BUF_UNLOCK(bp); 1783} 1784 1785/* 1786 * Release a buffer back to the appropriate queue but do not try to free 1787 * it. The buffer is expected to be used again soon. 1788 * 1789 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1790 * biodone() to requeue an async I/O on completion. It is also used when 1791 * known good buffers need to be requeued but we think we may need the data 1792 * again soon. 1793 * 1794 * XXX we should be able to leave the B_RELBUF hint set on completion. 1795 */ 1796void 1797bqrelse(struct buf *bp) 1798{ 1799 int qindex; 1800 1801 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1802 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1803 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1804 1805 if (BUF_LOCKRECURSED(bp)) { 1806 /* do not release to free list */ 1807 BUF_UNLOCK(bp); 1808 return; 1809 } 1810 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1811 1812 if (bp->b_flags & B_MANAGED) { 1813 if (bp->b_flags & B_REMFREE) 1814 bremfreef(bp); 1815 goto out; 1816 } 1817 1818 /* buffers with stale but valid contents */ 1819 if (bp->b_flags & B_DELWRI) { 1820 qindex = QUEUE_DIRTY; 1821 } else { 1822 if ((bp->b_flags & B_DELWRI) == 0 && 1823 (bp->b_xflags & BX_VNDIRTY)) 1824 panic("bqrelse: not dirty"); 1825 /* 1826 * BKGRDINPROG can only be set with the buf and bufobj 1827 * locks both held. We tolerate a race to clear it here. 1828 */ 1829 if (buf_vm_page_count_severe() && 1830 (bp->b_vflags & BV_BKGRDINPROG) == 0) { 1831 /* 1832 * We are too low on memory, we have to try to free 1833 * the buffer (most importantly: the wired pages 1834 * making up its backing store) *now*. 1835 */ 1836 brelse(bp); 1837 return; 1838 } 1839 qindex = QUEUE_CLEAN; 1840 } 1841 binsfree(bp, qindex); 1842 1843out: 1844 /* unlock */ 1845 BUF_UNLOCK(bp); 1846} 1847 1848/* Give pages used by the bp back to the VM system (where possible) */ 1849static void 1850vfs_vmio_release(struct buf *bp) 1851{ 1852 int i; 1853 vm_page_t m; 1854 1855 if ((bp->b_flags & B_UNMAPPED) == 0) { 1856 BUF_CHECK_MAPPED(bp); 1857 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages); 1858 } else 1859 BUF_CHECK_UNMAPPED(bp); 1860 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 1861 for (i = 0; i < bp->b_npages; i++) { 1862 m = bp->b_pages[i]; 1863 bp->b_pages[i] = NULL; 1864 /* 1865 * In order to keep page LRU ordering consistent, put 1866 * everything on the inactive queue. 1867 */ 1868 vm_page_lock(m); 1869 vm_page_unwire(m, 0); 1870 1871 /* 1872 * Might as well free the page if we can and it has 1873 * no valid data. We also free the page if the 1874 * buffer was used for direct I/O 1875 */ 1876 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid) { 1877 if (m->wire_count == 0 && !vm_page_busied(m)) 1878 vm_page_free(m); 1879 } else if (bp->b_flags & B_DIRECT) 1880 vm_page_try_to_free(m); 1881 else if (buf_vm_page_count_severe()) 1882 vm_page_try_to_cache(m); 1883 vm_page_unlock(m); 1884 } 1885 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 1886 1887 if (bp->b_bufsize) { 1888 bufspacewakeup(); 1889 bp->b_bufsize = 0; 1890 } 1891 bp->b_npages = 0; 1892 bp->b_flags &= ~B_VMIO; 1893 if (bp->b_vp) 1894 brelvp(bp); 1895} 1896 1897/* 1898 * Check to see if a block at a particular lbn is available for a clustered 1899 * write. 1900 */ 1901static int 1902vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 1903{ 1904 struct buf *bpa; 1905 int match; 1906 1907 match = 0; 1908 1909 /* If the buf isn't in core skip it */ 1910 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 1911 return (0); 1912 1913 /* If the buf is busy we don't want to wait for it */ 1914 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1915 return (0); 1916 1917 /* Only cluster with valid clusterable delayed write buffers */ 1918 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 1919 (B_DELWRI | B_CLUSTEROK)) 1920 goto done; 1921 1922 if (bpa->b_bufsize != size) 1923 goto done; 1924 1925 /* 1926 * Check to see if it is in the expected place on disk and that the 1927 * block has been mapped. 1928 */ 1929 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 1930 match = 1; 1931done: 1932 BUF_UNLOCK(bpa); 1933 return (match); 1934} 1935 1936/* 1937 * vfs_bio_awrite: 1938 * 1939 * Implement clustered async writes for clearing out B_DELWRI buffers. 1940 * This is much better then the old way of writing only one buffer at 1941 * a time. Note that we may not be presented with the buffers in the 1942 * correct order, so we search for the cluster in both directions. 1943 */ 1944int 1945vfs_bio_awrite(struct buf *bp) 1946{ 1947 struct bufobj *bo; 1948 int i; 1949 int j; 1950 daddr_t lblkno = bp->b_lblkno; 1951 struct vnode *vp = bp->b_vp; 1952 int ncl; 1953 int nwritten; 1954 int size; 1955 int maxcl; 1956 int gbflags; 1957 1958 bo = &vp->v_bufobj; 1959 gbflags = (bp->b_flags & B_UNMAPPED) != 0 ? GB_UNMAPPED : 0; 1960 /* 1961 * right now we support clustered writing only to regular files. If 1962 * we find a clusterable block we could be in the middle of a cluster 1963 * rather then at the beginning. 1964 */ 1965 if ((vp->v_type == VREG) && 1966 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1967 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1968 1969 size = vp->v_mount->mnt_stat.f_iosize; 1970 maxcl = MAXPHYS / size; 1971 1972 BO_RLOCK(bo); 1973 for (i = 1; i < maxcl; i++) 1974 if (vfs_bio_clcheck(vp, size, lblkno + i, 1975 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 1976 break; 1977 1978 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 1979 if (vfs_bio_clcheck(vp, size, lblkno - j, 1980 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 1981 break; 1982 BO_RUNLOCK(bo); 1983 --j; 1984 ncl = i + j; 1985 /* 1986 * this is a possible cluster write 1987 */ 1988 if (ncl != 1) { 1989 BUF_UNLOCK(bp); 1990 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl, 1991 gbflags); 1992 return (nwritten); 1993 } 1994 } 1995 bremfree(bp); 1996 bp->b_flags |= B_ASYNC; 1997 /* 1998 * default (old) behavior, writing out only one block 1999 * 2000 * XXX returns b_bufsize instead of b_bcount for nwritten? 2001 */ 2002 nwritten = bp->b_bufsize; 2003 (void) bwrite(bp); 2004 2005 return (nwritten); 2006} 2007 2008static void 2009setbufkva(struct buf *bp, vm_offset_t addr, int maxsize, int gbflags) 2010{ 2011 2012 KASSERT((bp->b_flags & (B_UNMAPPED | B_KVAALLOC)) == 0 && 2013 bp->b_kvasize == 0, ("call bfreekva(%p)", bp)); 2014 if ((gbflags & GB_UNMAPPED) == 0) { 2015 bp->b_kvabase = (caddr_t)addr; 2016 } else if ((gbflags & GB_KVAALLOC) != 0) { 2017 KASSERT((gbflags & GB_UNMAPPED) != 0, 2018 ("GB_KVAALLOC without GB_UNMAPPED")); 2019 bp->b_kvaalloc = (caddr_t)addr; 2020 bp->b_flags |= B_UNMAPPED | B_KVAALLOC; 2021 atomic_add_long(&unmapped_bufspace, bp->b_kvasize); 2022 } 2023 bp->b_kvasize = maxsize; 2024} 2025 2026/* 2027 * Allocate the buffer KVA and set b_kvasize. Also set b_kvabase if 2028 * needed. 2029 */ 2030static int 2031allocbufkva(struct buf *bp, int maxsize, int gbflags) 2032{ 2033 vm_offset_t addr; 2034 2035 bfreekva(bp); 2036 addr = 0; 2037 2038 if (vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr)) { 2039 /* 2040 * Buffer map is too fragmented. Request the caller 2041 * to defragment the map. 2042 */ 2043 atomic_add_int(&bufdefragcnt, 1); 2044 return (1); 2045 } 2046 setbufkva(bp, addr, maxsize, gbflags); 2047 atomic_add_long(&bufspace, bp->b_kvasize); 2048 return (0); 2049} 2050 2051/* 2052 * Ask the bufdaemon for help, or act as bufdaemon itself, when a 2053 * locked vnode is supplied. 2054 */ 2055static void 2056getnewbuf_bufd_help(struct vnode *vp, int gbflags, int slpflag, int slptimeo, 2057 int defrag) 2058{ 2059 struct thread *td; 2060 char *waitmsg; 2061 int cnt, error, flags, norunbuf, wait; 2062 2063 mtx_assert(&bqclean, MA_OWNED); 2064 2065 if (defrag) { 2066 flags = VFS_BIO_NEED_BUFSPACE; 2067 waitmsg = "nbufkv"; 2068 } else if (bufspace >= hibufspace) { 2069 waitmsg = "nbufbs"; 2070 flags = VFS_BIO_NEED_BUFSPACE; 2071 } else { 2072 waitmsg = "newbuf"; 2073 flags = VFS_BIO_NEED_ANY; 2074 } 2075 atomic_set_int(&needsbuffer, flags); 2076 mtx_unlock(&bqclean); 2077 2078 bd_speedup(); /* heeeelp */ 2079 if ((gbflags & GB_NOWAIT_BD) != 0) 2080 return; 2081 2082 td = curthread; 2083 cnt = 0; 2084 wait = MNT_NOWAIT; 2085 rw_wlock(&nblock); 2086 while ((needsbuffer & flags) != 0) { 2087 if (vp != NULL && vp->v_type != VCHR && 2088 (td->td_pflags & TDP_BUFNEED) == 0) { 2089 rw_wunlock(&nblock); 2090 /* 2091 * getblk() is called with a vnode locked, and 2092 * some majority of the dirty buffers may as 2093 * well belong to the vnode. Flushing the 2094 * buffers there would make a progress that 2095 * cannot be achieved by the buf_daemon, that 2096 * cannot lock the vnode. 2097 */ 2098 if (cnt++ > 2) 2099 wait = MNT_WAIT; 2100 ASSERT_VOP_LOCKED(vp, "bufd_helper"); 2101 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 : 2102 vn_lock(vp, LK_TRYUPGRADE); 2103 if (error == 0) { 2104 /* play bufdaemon */ 2105 norunbuf = curthread_pflags_set(TDP_BUFNEED | 2106 TDP_NORUNNINGBUF); 2107 VOP_FSYNC(vp, wait, td); 2108 atomic_add_long(¬bufdflushes, 1); 2109 curthread_pflags_restore(norunbuf); 2110 } 2111 rw_wlock(&nblock); 2112 if ((needsbuffer & flags) == 0) 2113 break; 2114 } 2115 error = rw_sleep(__DEVOLATILE(void *, &needsbuffer), &nblock, 2116 (PRIBIO + 4) | slpflag, waitmsg, slptimeo); 2117 if (error != 0) 2118 break; 2119 } 2120 rw_wunlock(&nblock); 2121} 2122 2123static void 2124getnewbuf_reuse_bp(struct buf *bp, int qindex) 2125{ 2126 2127 CTR6(KTR_BUF, "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d " 2128 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags, 2129 bp->b_kvasize, bp->b_bufsize, qindex); 2130 mtx_assert(&bqclean, MA_NOTOWNED); 2131 2132 /* 2133 * Note: we no longer distinguish between VMIO and non-VMIO 2134 * buffers. 2135 */ 2136 KASSERT((bp->b_flags & B_DELWRI) == 0, 2137 ("delwri buffer %p found in queue %d", bp, qindex)); 2138 2139 if (qindex == QUEUE_CLEAN) { 2140 if (bp->b_flags & B_VMIO) { 2141 bp->b_flags &= ~B_ASYNC; 2142 vfs_vmio_release(bp); 2143 } 2144 if (bp->b_vp != NULL) 2145 brelvp(bp); 2146 } 2147 2148 /* 2149 * Get the rest of the buffer freed up. b_kva* is still valid 2150 * after this operation. 2151 */ 2152 2153 if (bp->b_rcred != NOCRED) { 2154 crfree(bp->b_rcred); 2155 bp->b_rcred = NOCRED; 2156 } 2157 if (bp->b_wcred != NOCRED) { 2158 crfree(bp->b_wcred); 2159 bp->b_wcred = NOCRED; 2160 } 2161 if (!LIST_EMPTY(&bp->b_dep)) 2162 buf_deallocate(bp); 2163 if (bp->b_vflags & BV_BKGRDINPROG) 2164 panic("losing buffer 3"); 2165 KASSERT(bp->b_vp == NULL, ("bp: %p still has vnode %p. qindex: %d", 2166 bp, bp->b_vp, qindex)); 2167 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 2168 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags)); 2169 2170 if (bp->b_bufsize) 2171 allocbuf(bp, 0); 2172 2173 bp->b_flags &= B_UNMAPPED | B_KVAALLOC; 2174 bp->b_ioflags = 0; 2175 bp->b_xflags = 0; 2176 KASSERT((bp->b_flags & B_INFREECNT) == 0, 2177 ("buf %p still counted as free?", bp)); 2178 bp->b_vflags = 0; 2179 bp->b_vp = NULL; 2180 bp->b_blkno = bp->b_lblkno = 0; 2181 bp->b_offset = NOOFFSET; 2182 bp->b_iodone = 0; 2183 bp->b_error = 0; 2184 bp->b_resid = 0; 2185 bp->b_bcount = 0; 2186 bp->b_npages = 0; 2187 bp->b_dirtyoff = bp->b_dirtyend = 0; 2188 bp->b_bufobj = NULL; 2189 bp->b_pin_count = 0; 2190 bp->b_fsprivate1 = NULL; 2191 bp->b_fsprivate2 = NULL; 2192 bp->b_fsprivate3 = NULL; 2193 2194 LIST_INIT(&bp->b_dep); 2195} 2196 2197static int flushingbufs; 2198 2199static struct buf * 2200getnewbuf_scan(int maxsize, int defrag, int unmapped, int metadata) 2201{ 2202 struct buf *bp, *nbp; 2203 int nqindex, qindex, pass; 2204 2205 KASSERT(!unmapped || !defrag, ("both unmapped and defrag")); 2206 2207 pass = 1; 2208restart: 2209 atomic_add_int(&getnewbufrestarts, 1); 2210 2211 /* 2212 * Setup for scan. If we do not have enough free buffers, 2213 * we setup a degenerate case that immediately fails. Note 2214 * that if we are specially marked process, we are allowed to 2215 * dip into our reserves. 2216 * 2217 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 2218 * for the allocation of the mapped buffer. For unmapped, the 2219 * easiest is to start with EMPTY outright. 2220 * 2221 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 2222 * However, there are a number of cases (defragging, reusing, ...) 2223 * where we cannot backup. 2224 */ 2225 nbp = NULL; 2226 mtx_lock(&bqclean); 2227 if (!defrag && unmapped) { 2228 nqindex = QUEUE_EMPTY; 2229 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 2230 } 2231 if (nbp == NULL) { 2232 nqindex = QUEUE_EMPTYKVA; 2233 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 2234 } 2235 2236 /* 2237 * If no EMPTYKVA buffers and we are either defragging or 2238 * reusing, locate a CLEAN buffer to free or reuse. If 2239 * bufspace useage is low skip this step so we can allocate a 2240 * new buffer. 2241 */ 2242 if (nbp == NULL && (defrag || bufspace >= lobufspace)) { 2243 nqindex = QUEUE_CLEAN; 2244 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2245 } 2246 2247 /* 2248 * If we could not find or were not allowed to reuse a CLEAN 2249 * buffer, check to see if it is ok to use an EMPTY buffer. 2250 * We can only use an EMPTY buffer if allocating its KVA would 2251 * not otherwise run us out of buffer space. No KVA is needed 2252 * for the unmapped allocation. 2253 */ 2254 if (nbp == NULL && defrag == 0 && (bufspace + maxsize < hibufspace || 2255 metadata)) { 2256 nqindex = QUEUE_EMPTY; 2257 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 2258 } 2259 2260 /* 2261 * All available buffers might be clean, retry ignoring the 2262 * lobufspace as the last resort. 2263 */ 2264 if (nbp == NULL && !TAILQ_EMPTY(&bufqueues[QUEUE_CLEAN])) { 2265 nqindex = QUEUE_CLEAN; 2266 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2267 } 2268 2269 /* 2270 * Run scan, possibly freeing data and/or kva mappings on the fly 2271 * depending. 2272 */ 2273 while ((bp = nbp) != NULL) { 2274 qindex = nqindex; 2275 2276 /* 2277 * Calculate next bp (we can only use it if we do not 2278 * block or do other fancy things). 2279 */ 2280 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 2281 switch (qindex) { 2282 case QUEUE_EMPTY: 2283 nqindex = QUEUE_EMPTYKVA; 2284 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 2285 if (nbp != NULL) 2286 break; 2287 /* FALLTHROUGH */ 2288 case QUEUE_EMPTYKVA: 2289 nqindex = QUEUE_CLEAN; 2290 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2291 if (nbp != NULL) 2292 break; 2293 /* FALLTHROUGH */ 2294 case QUEUE_CLEAN: 2295 if (metadata && pass == 1) { 2296 pass = 2; 2297 nqindex = QUEUE_EMPTY; 2298 nbp = TAILQ_FIRST( 2299 &bufqueues[QUEUE_EMPTY]); 2300 } 2301 /* 2302 * nbp is NULL. 2303 */ 2304 break; 2305 } 2306 } 2307 /* 2308 * If we are defragging then we need a buffer with 2309 * b_kvasize != 0. XXX this situation should no longer 2310 * occur, if defrag is non-zero the buffer's b_kvasize 2311 * should also be non-zero at this point. XXX 2312 */ 2313 if (defrag && bp->b_kvasize == 0) { 2314 printf("Warning: defrag empty buffer %p\n", bp); 2315 continue; 2316 } 2317 2318 /* 2319 * Start freeing the bp. This is somewhat involved. nbp 2320 * remains valid only for QUEUE_EMPTY[KVA] bp's. 2321 */ 2322 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2323 continue; 2324 /* 2325 * BKGRDINPROG can only be set with the buf and bufobj 2326 * locks both held. We tolerate a race to clear it here. 2327 */ 2328 if (bp->b_vflags & BV_BKGRDINPROG) { 2329 BUF_UNLOCK(bp); 2330 continue; 2331 } 2332 2333 KASSERT(bp->b_qindex == qindex, 2334 ("getnewbuf: inconsistent queue %d bp %p", qindex, bp)); 2335 2336 bremfreel(bp); 2337 mtx_unlock(&bqclean); 2338 /* 2339 * NOTE: nbp is now entirely invalid. We can only restart 2340 * the scan from this point on. 2341 */ 2342 2343 getnewbuf_reuse_bp(bp, qindex); 2344 mtx_assert(&bqclean, MA_NOTOWNED); 2345 2346 /* 2347 * If we are defragging then free the buffer. 2348 */ 2349 if (defrag) { 2350 bp->b_flags |= B_INVAL; 2351 bfreekva(bp); 2352 brelse(bp); 2353 defrag = 0; 2354 goto restart; 2355 } 2356 2357 /* 2358 * Notify any waiters for the buffer lock about 2359 * identity change by freeing the buffer. 2360 */ 2361 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp)) { 2362 bp->b_flags |= B_INVAL; 2363 bfreekva(bp); 2364 brelse(bp); 2365 goto restart; 2366 } 2367 2368 if (metadata) 2369 break; 2370 2371 /* 2372 * If we are overcomitted then recover the buffer and its 2373 * KVM space. This occurs in rare situations when multiple 2374 * processes are blocked in getnewbuf() or allocbuf(). 2375 */ 2376 if (bufspace >= hibufspace) 2377 flushingbufs = 1; 2378 if (flushingbufs && bp->b_kvasize != 0) { 2379 bp->b_flags |= B_INVAL; 2380 bfreekva(bp); 2381 brelse(bp); 2382 goto restart; 2383 } 2384 if (bufspace < lobufspace) 2385 flushingbufs = 0; 2386 break; 2387 } 2388 return (bp); 2389} 2390 2391/* 2392 * getnewbuf: 2393 * 2394 * Find and initialize a new buffer header, freeing up existing buffers 2395 * in the bufqueues as necessary. The new buffer is returned locked. 2396 * 2397 * Important: B_INVAL is not set. If the caller wishes to throw the 2398 * buffer away, the caller must set B_INVAL prior to calling brelse(). 2399 * 2400 * We block if: 2401 * We have insufficient buffer headers 2402 * We have insufficient buffer space 2403 * buffer_arena is too fragmented ( space reservation fails ) 2404 * If we have to flush dirty buffers ( but we try to avoid this ) 2405 */ 2406static struct buf * 2407getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int size, int maxsize, 2408 int gbflags) 2409{ 2410 struct buf *bp; 2411 int defrag, metadata; 2412 2413 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 2414 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 2415 if (!unmapped_buf_allowed) 2416 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC); 2417 2418 defrag = 0; 2419 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 || 2420 vp->v_type == VCHR) 2421 metadata = 1; 2422 else 2423 metadata = 0; 2424 /* 2425 * We can't afford to block since we might be holding a vnode lock, 2426 * which may prevent system daemons from running. We deal with 2427 * low-memory situations by proactively returning memory and running 2428 * async I/O rather then sync I/O. 2429 */ 2430 atomic_add_int(&getnewbufcalls, 1); 2431 atomic_subtract_int(&getnewbufrestarts, 1); 2432restart: 2433 bp = getnewbuf_scan(maxsize, defrag, (gbflags & (GB_UNMAPPED | 2434 GB_KVAALLOC)) == GB_UNMAPPED, metadata); 2435 if (bp != NULL) 2436 defrag = 0; 2437 2438 /* 2439 * If we exhausted our list, sleep as appropriate. We may have to 2440 * wakeup various daemons and write out some dirty buffers. 2441 * 2442 * Generally we are sleeping due to insufficient buffer space. 2443 */ 2444 if (bp == NULL) { 2445 mtx_assert(&bqclean, MA_OWNED); 2446 getnewbuf_bufd_help(vp, gbflags, slpflag, slptimeo, defrag); 2447 mtx_assert(&bqclean, MA_NOTOWNED); 2448 } else if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == GB_UNMAPPED) { 2449 mtx_assert(&bqclean, MA_NOTOWNED); 2450 2451 bfreekva(bp); 2452 bp->b_flags |= B_UNMAPPED; 2453 bp->b_kvabase = bp->b_data = unmapped_buf; 2454 bp->b_kvasize = maxsize; 2455 atomic_add_long(&bufspace, bp->b_kvasize); 2456 atomic_add_long(&unmapped_bufspace, bp->b_kvasize); 2457 atomic_add_int(&bufreusecnt, 1); 2458 } else { 2459 mtx_assert(&bqclean, MA_NOTOWNED); 2460 2461 /* 2462 * We finally have a valid bp. We aren't quite out of the 2463 * woods, we still have to reserve kva space. In order 2464 * to keep fragmentation sane we only allocate kva in 2465 * BKVASIZE chunks. 2466 */ 2467 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2468 2469 if (maxsize != bp->b_kvasize || (bp->b_flags & (B_UNMAPPED | 2470 B_KVAALLOC)) == B_UNMAPPED) { 2471 if (allocbufkva(bp, maxsize, gbflags)) { 2472 defrag = 1; 2473 bp->b_flags |= B_INVAL; 2474 brelse(bp); 2475 goto restart; 2476 } 2477 atomic_add_int(&bufreusecnt, 1); 2478 } else if ((bp->b_flags & B_KVAALLOC) != 0 && 2479 (gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == 0) { 2480 /* 2481 * If the reused buffer has KVA allocated, 2482 * reassign b_kvaalloc to b_kvabase. 2483 */ 2484 bp->b_kvabase = bp->b_kvaalloc; 2485 bp->b_flags &= ~B_KVAALLOC; 2486 atomic_subtract_long(&unmapped_bufspace, 2487 bp->b_kvasize); 2488 atomic_add_int(&bufreusecnt, 1); 2489 } else if ((bp->b_flags & (B_UNMAPPED | B_KVAALLOC)) == 0 && 2490 (gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == (GB_UNMAPPED | 2491 GB_KVAALLOC)) { 2492 /* 2493 * The case of reused buffer already have KVA 2494 * mapped, but the request is for unmapped 2495 * buffer with KVA allocated. 2496 */ 2497 bp->b_kvaalloc = bp->b_kvabase; 2498 bp->b_data = bp->b_kvabase = unmapped_buf; 2499 bp->b_flags |= B_UNMAPPED | B_KVAALLOC; 2500 atomic_add_long(&unmapped_bufspace, 2501 bp->b_kvasize); 2502 atomic_add_int(&bufreusecnt, 1); 2503 } 2504 if ((gbflags & GB_UNMAPPED) == 0) { 2505 bp->b_saveaddr = bp->b_kvabase; 2506 bp->b_data = bp->b_saveaddr; 2507 bp->b_flags &= ~B_UNMAPPED; 2508 BUF_CHECK_MAPPED(bp); 2509 } 2510 } 2511 return (bp); 2512} 2513 2514/* 2515 * buf_daemon: 2516 * 2517 * buffer flushing daemon. Buffers are normally flushed by the 2518 * update daemon but if it cannot keep up this process starts to 2519 * take the load in an attempt to prevent getnewbuf() from blocking. 2520 */ 2521 2522static struct kproc_desc buf_kp = { 2523 "bufdaemon", 2524 buf_daemon, 2525 &bufdaemonproc 2526}; 2527SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 2528 2529static int 2530buf_flush(int target) 2531{ 2532 int flushed; 2533 2534 flushed = flushbufqueues(target, 0); 2535 if (flushed == 0) { 2536 /* 2537 * Could not find any buffers without rollback 2538 * dependencies, so just write the first one 2539 * in the hopes of eventually making progress. 2540 */ 2541 flushed = flushbufqueues(target, 1); 2542 } 2543 return (flushed); 2544} 2545 2546static void 2547buf_daemon() 2548{ 2549 int lodirty; 2550 2551 /* 2552 * This process needs to be suspended prior to shutdown sync. 2553 */ 2554 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2555 SHUTDOWN_PRI_LAST); 2556 2557 /* 2558 * This process is allowed to take the buffer cache to the limit 2559 */ 2560 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 2561 mtx_lock(&bdlock); 2562 for (;;) { 2563 bd_request = 0; 2564 mtx_unlock(&bdlock); 2565 2566 kproc_suspend_check(bufdaemonproc); 2567 lodirty = lodirtybuffers; 2568 if (bd_speedupreq) { 2569 lodirty = numdirtybuffers / 2; 2570 bd_speedupreq = 0; 2571 } 2572 /* 2573 * Do the flush. Limit the amount of in-transit I/O we 2574 * allow to build up, otherwise we would completely saturate 2575 * the I/O system. 2576 */ 2577 while (numdirtybuffers > lodirty) { 2578 if (buf_flush(numdirtybuffers - lodirty) == 0) 2579 break; 2580 kern_yield(PRI_USER); 2581 } 2582 2583 /* 2584 * Only clear bd_request if we have reached our low water 2585 * mark. The buf_daemon normally waits 1 second and 2586 * then incrementally flushes any dirty buffers that have 2587 * built up, within reason. 2588 * 2589 * If we were unable to hit our low water mark and couldn't 2590 * find any flushable buffers, we sleep for a short period 2591 * to avoid endless loops on unlockable buffers. 2592 */ 2593 mtx_lock(&bdlock); 2594 if (numdirtybuffers <= lodirtybuffers) { 2595 /* 2596 * We reached our low water mark, reset the 2597 * request and sleep until we are needed again. 2598 * The sleep is just so the suspend code works. 2599 */ 2600 bd_request = 0; 2601 /* 2602 * Do an extra wakeup in case dirty threshold 2603 * changed via sysctl and the explicit transition 2604 * out of shortfall was missed. 2605 */ 2606 bdirtywakeup(); 2607 if (runningbufspace <= lorunningspace) 2608 runningwakeup(); 2609 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 2610 } else { 2611 /* 2612 * We couldn't find any flushable dirty buffers but 2613 * still have too many dirty buffers, we 2614 * have to sleep and try again. (rare) 2615 */ 2616 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 2617 } 2618 } 2619} 2620 2621/* 2622 * flushbufqueues: 2623 * 2624 * Try to flush a buffer in the dirty queue. We must be careful to 2625 * free up B_INVAL buffers instead of write them, which NFS is 2626 * particularly sensitive to. 2627 */ 2628static int flushwithdeps = 0; 2629SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 2630 0, "Number of buffers flushed with dependecies that require rollbacks"); 2631 2632static int 2633flushbufqueues(int target, int flushdeps) 2634{ 2635 struct buf *sentinel; 2636 struct vnode *vp; 2637 struct mount *mp; 2638 struct buf *bp; 2639 int hasdeps; 2640 int flushed; 2641 int queue; 2642 int error; 2643 2644 flushed = 0; 2645 queue = QUEUE_DIRTY; 2646 bp = NULL; 2647 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 2648 sentinel->b_qindex = QUEUE_SENTINEL; 2649 mtx_lock(&bqdirty); 2650 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist); 2651 mtx_unlock(&bqdirty); 2652 while (flushed != target) { 2653 maybe_yield(); 2654 mtx_lock(&bqdirty); 2655 bp = TAILQ_NEXT(sentinel, b_freelist); 2656 if (bp != NULL) { 2657 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2658 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel, 2659 b_freelist); 2660 } else { 2661 mtx_unlock(&bqdirty); 2662 break; 2663 } 2664 KASSERT(bp->b_qindex != QUEUE_SENTINEL, 2665 ("parallel calls to flushbufqueues() bp %p", bp)); 2666 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL); 2667 mtx_unlock(&bqdirty); 2668 if (error != 0) 2669 continue; 2670 if (bp->b_pin_count > 0) { 2671 BUF_UNLOCK(bp); 2672 continue; 2673 } 2674 /* 2675 * BKGRDINPROG can only be set with the buf and bufobj 2676 * locks both held. We tolerate a race to clear it here. 2677 */ 2678 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 2679 (bp->b_flags & B_DELWRI) == 0) { 2680 BUF_UNLOCK(bp); 2681 continue; 2682 } 2683 if (bp->b_flags & B_INVAL) { 2684 bremfreef(bp); 2685 brelse(bp); 2686 flushed++; 2687 continue; 2688 } 2689 2690 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 2691 if (flushdeps == 0) { 2692 BUF_UNLOCK(bp); 2693 continue; 2694 } 2695 hasdeps = 1; 2696 } else 2697 hasdeps = 0; 2698 /* 2699 * We must hold the lock on a vnode before writing 2700 * one of its buffers. Otherwise we may confuse, or 2701 * in the case of a snapshot vnode, deadlock the 2702 * system. 2703 * 2704 * The lock order here is the reverse of the normal 2705 * of vnode followed by buf lock. This is ok because 2706 * the NOWAIT will prevent deadlock. 2707 */ 2708 vp = bp->b_vp; 2709 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 2710 BUF_UNLOCK(bp); 2711 continue; 2712 } 2713 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT); 2714 if (error == 0) { 2715 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 2716 bp, bp->b_vp, bp->b_flags); 2717 vfs_bio_awrite(bp); 2718 vn_finished_write(mp); 2719 VOP_UNLOCK(vp, 0); 2720 flushwithdeps += hasdeps; 2721 flushed++; 2722 if (runningbufspace > hirunningspace) 2723 waitrunningbufspace(); 2724 continue; 2725 } 2726 vn_finished_write(mp); 2727 BUF_UNLOCK(bp); 2728 } 2729 mtx_lock(&bqdirty); 2730 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2731 mtx_unlock(&bqdirty); 2732 free(sentinel, M_TEMP); 2733 return (flushed); 2734} 2735 2736/* 2737 * Check to see if a block is currently memory resident. 2738 */ 2739struct buf * 2740incore(struct bufobj *bo, daddr_t blkno) 2741{ 2742 struct buf *bp; 2743 2744 BO_RLOCK(bo); 2745 bp = gbincore(bo, blkno); 2746 BO_RUNLOCK(bo); 2747 return (bp); 2748} 2749 2750/* 2751 * Returns true if no I/O is needed to access the 2752 * associated VM object. This is like incore except 2753 * it also hunts around in the VM system for the data. 2754 */ 2755 2756static int 2757inmem(struct vnode * vp, daddr_t blkno) 2758{ 2759 vm_object_t obj; 2760 vm_offset_t toff, tinc, size; 2761 vm_page_t m; 2762 vm_ooffset_t off; 2763 2764 ASSERT_VOP_LOCKED(vp, "inmem"); 2765 2766 if (incore(&vp->v_bufobj, blkno)) 2767 return 1; 2768 if (vp->v_mount == NULL) 2769 return 0; 2770 obj = vp->v_object; 2771 if (obj == NULL) 2772 return (0); 2773 2774 size = PAGE_SIZE; 2775 if (size > vp->v_mount->mnt_stat.f_iosize) 2776 size = vp->v_mount->mnt_stat.f_iosize; 2777 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2778 2779 VM_OBJECT_RLOCK(obj); 2780 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2781 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2782 if (!m) 2783 goto notinmem; 2784 tinc = size; 2785 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2786 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2787 if (vm_page_is_valid(m, 2788 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2789 goto notinmem; 2790 } 2791 VM_OBJECT_RUNLOCK(obj); 2792 return 1; 2793 2794notinmem: 2795 VM_OBJECT_RUNLOCK(obj); 2796 return (0); 2797} 2798 2799/* 2800 * Set the dirty range for a buffer based on the status of the dirty 2801 * bits in the pages comprising the buffer. The range is limited 2802 * to the size of the buffer. 2803 * 2804 * Tell the VM system that the pages associated with this buffer 2805 * are clean. This is used for delayed writes where the data is 2806 * going to go to disk eventually without additional VM intevention. 2807 * 2808 * Note that while we only really need to clean through to b_bcount, we 2809 * just go ahead and clean through to b_bufsize. 2810 */ 2811static void 2812vfs_clean_pages_dirty_buf(struct buf *bp) 2813{ 2814 vm_ooffset_t foff, noff, eoff; 2815 vm_page_t m; 2816 int i; 2817 2818 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 2819 return; 2820 2821 foff = bp->b_offset; 2822 KASSERT(bp->b_offset != NOOFFSET, 2823 ("vfs_clean_pages_dirty_buf: no buffer offset")); 2824 2825 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 2826 vfs_drain_busy_pages(bp); 2827 vfs_setdirty_locked_object(bp); 2828 for (i = 0; i < bp->b_npages; i++) { 2829 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2830 eoff = noff; 2831 if (eoff > bp->b_offset + bp->b_bufsize) 2832 eoff = bp->b_offset + bp->b_bufsize; 2833 m = bp->b_pages[i]; 2834 vfs_page_set_validclean(bp, foff, m); 2835 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 2836 foff = noff; 2837 } 2838 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 2839} 2840 2841static void 2842vfs_setdirty_locked_object(struct buf *bp) 2843{ 2844 vm_object_t object; 2845 int i; 2846 2847 object = bp->b_bufobj->bo_object; 2848 VM_OBJECT_ASSERT_WLOCKED(object); 2849 2850 /* 2851 * We qualify the scan for modified pages on whether the 2852 * object has been flushed yet. 2853 */ 2854 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) { 2855 vm_offset_t boffset; 2856 vm_offset_t eoffset; 2857 2858 /* 2859 * test the pages to see if they have been modified directly 2860 * by users through the VM system. 2861 */ 2862 for (i = 0; i < bp->b_npages; i++) 2863 vm_page_test_dirty(bp->b_pages[i]); 2864 2865 /* 2866 * Calculate the encompassing dirty range, boffset and eoffset, 2867 * (eoffset - boffset) bytes. 2868 */ 2869 2870 for (i = 0; i < bp->b_npages; i++) { 2871 if (bp->b_pages[i]->dirty) 2872 break; 2873 } 2874 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2875 2876 for (i = bp->b_npages - 1; i >= 0; --i) { 2877 if (bp->b_pages[i]->dirty) { 2878 break; 2879 } 2880 } 2881 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2882 2883 /* 2884 * Fit it to the buffer. 2885 */ 2886 2887 if (eoffset > bp->b_bcount) 2888 eoffset = bp->b_bcount; 2889 2890 /* 2891 * If we have a good dirty range, merge with the existing 2892 * dirty range. 2893 */ 2894 2895 if (boffset < eoffset) { 2896 if (bp->b_dirtyoff > boffset) 2897 bp->b_dirtyoff = boffset; 2898 if (bp->b_dirtyend < eoffset) 2899 bp->b_dirtyend = eoffset; 2900 } 2901 } 2902} 2903 2904/* 2905 * Allocate the KVA mapping for an existing buffer. It handles the 2906 * cases of both B_UNMAPPED buffer, and buffer with the preallocated 2907 * KVA which is not mapped (B_KVAALLOC). 2908 */ 2909static void 2910bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags) 2911{ 2912 struct buf *scratch_bp; 2913 int bsize, maxsize, need_mapping, need_kva; 2914 off_t offset; 2915 2916 need_mapping = (bp->b_flags & B_UNMAPPED) != 0 && 2917 (gbflags & GB_UNMAPPED) == 0; 2918 need_kva = (bp->b_flags & (B_KVAALLOC | B_UNMAPPED)) == B_UNMAPPED && 2919 (gbflags & GB_KVAALLOC) != 0; 2920 if (!need_mapping && !need_kva) 2921 return; 2922 2923 BUF_CHECK_UNMAPPED(bp); 2924 2925 if (need_mapping && (bp->b_flags & B_KVAALLOC) != 0) { 2926 /* 2927 * Buffer is not mapped, but the KVA was already 2928 * reserved at the time of the instantiation. Use the 2929 * allocated space. 2930 */ 2931 bp->b_flags &= ~B_KVAALLOC; 2932 KASSERT(bp->b_kvaalloc != 0, ("kvaalloc == 0")); 2933 bp->b_kvabase = bp->b_kvaalloc; 2934 atomic_subtract_long(&unmapped_bufspace, bp->b_kvasize); 2935 goto has_addr; 2936 } 2937 2938 /* 2939 * Calculate the amount of the address space we would reserve 2940 * if the buffer was mapped. 2941 */ 2942 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize; 2943 offset = blkno * bsize; 2944 maxsize = size + (offset & PAGE_MASK); 2945 maxsize = imax(maxsize, bsize); 2946 2947mapping_loop: 2948 if (allocbufkva(bp, maxsize, gbflags)) { 2949 /* 2950 * Request defragmentation. getnewbuf() returns us the 2951 * allocated space by the scratch buffer KVA. 2952 */ 2953 scratch_bp = getnewbuf(bp->b_vp, 0, 0, size, maxsize, gbflags | 2954 (GB_UNMAPPED | GB_KVAALLOC)); 2955 if (scratch_bp == NULL) { 2956 if ((gbflags & GB_NOWAIT_BD) != 0) { 2957 /* 2958 * XXXKIB: defragmentation cannot 2959 * succeed, not sure what else to do. 2960 */ 2961 panic("GB_NOWAIT_BD and B_UNMAPPED %p", bp); 2962 } 2963 atomic_add_int(&mappingrestarts, 1); 2964 goto mapping_loop; 2965 } 2966 KASSERT((scratch_bp->b_flags & B_KVAALLOC) != 0, 2967 ("scratch bp !B_KVAALLOC %p", scratch_bp)); 2968 setbufkva(bp, (vm_offset_t)scratch_bp->b_kvaalloc, 2969 scratch_bp->b_kvasize, gbflags); 2970 2971 /* Get rid of the scratch buffer. */ 2972 scratch_bp->b_kvasize = 0; 2973 scratch_bp->b_flags |= B_INVAL; 2974 scratch_bp->b_flags &= ~(B_UNMAPPED | B_KVAALLOC); 2975 brelse(scratch_bp); 2976 } 2977 if (!need_mapping) 2978 return; 2979 2980has_addr: 2981 bp->b_saveaddr = bp->b_kvabase; 2982 bp->b_data = bp->b_saveaddr; /* b_offset is handled by bpmap_qenter */ 2983 bp->b_flags &= ~B_UNMAPPED; 2984 BUF_CHECK_MAPPED(bp); 2985 bpmap_qenter(bp); 2986} 2987 2988/* 2989 * getblk: 2990 * 2991 * Get a block given a specified block and offset into a file/device. 2992 * The buffers B_DONE bit will be cleared on return, making it almost 2993 * ready for an I/O initiation. B_INVAL may or may not be set on 2994 * return. The caller should clear B_INVAL prior to initiating a 2995 * READ. 2996 * 2997 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2998 * an existing buffer. 2999 * 3000 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 3001 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 3002 * and then cleared based on the backing VM. If the previous buffer is 3003 * non-0-sized but invalid, B_CACHE will be cleared. 3004 * 3005 * If getblk() must create a new buffer, the new buffer is returned with 3006 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 3007 * case it is returned with B_INVAL clear and B_CACHE set based on the 3008 * backing VM. 3009 * 3010 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 3011 * B_CACHE bit is clear. 3012 * 3013 * What this means, basically, is that the caller should use B_CACHE to 3014 * determine whether the buffer is fully valid or not and should clear 3015 * B_INVAL prior to issuing a read. If the caller intends to validate 3016 * the buffer by loading its data area with something, the caller needs 3017 * to clear B_INVAL. If the caller does this without issuing an I/O, 3018 * the caller should set B_CACHE ( as an optimization ), else the caller 3019 * should issue the I/O and biodone() will set B_CACHE if the I/O was 3020 * a write attempt or if it was a successfull read. If the caller 3021 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 3022 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 3023 */ 3024struct buf * 3025getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3026 int flags) 3027{ 3028 struct buf *bp; 3029 struct bufobj *bo; 3030 int bsize, error, maxsize, vmio; 3031 off_t offset; 3032 3033 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 3034 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3035 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3036 ASSERT_VOP_LOCKED(vp, "getblk"); 3037 if (size > MAXBSIZE) 3038 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 3039 if (!unmapped_buf_allowed) 3040 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3041 3042 bo = &vp->v_bufobj; 3043loop: 3044 BO_RLOCK(bo); 3045 bp = gbincore(bo, blkno); 3046 if (bp != NULL) { 3047 int lockflags; 3048 /* 3049 * Buffer is in-core. If the buffer is not busy nor managed, 3050 * it must be on a queue. 3051 */ 3052 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 3053 3054 if (flags & GB_LOCK_NOWAIT) 3055 lockflags |= LK_NOWAIT; 3056 3057 error = BUF_TIMELOCK(bp, lockflags, 3058 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo); 3059 3060 /* 3061 * If we slept and got the lock we have to restart in case 3062 * the buffer changed identities. 3063 */ 3064 if (error == ENOLCK) 3065 goto loop; 3066 /* We timed out or were interrupted. */ 3067 else if (error) 3068 return (NULL); 3069 /* If recursed, assume caller knows the rules. */ 3070 else if (BUF_LOCKRECURSED(bp)) 3071 goto end; 3072 3073 /* 3074 * The buffer is locked. B_CACHE is cleared if the buffer is 3075 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 3076 * and for a VMIO buffer B_CACHE is adjusted according to the 3077 * backing VM cache. 3078 */ 3079 if (bp->b_flags & B_INVAL) 3080 bp->b_flags &= ~B_CACHE; 3081 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 3082 bp->b_flags |= B_CACHE; 3083 if (bp->b_flags & B_MANAGED) 3084 MPASS(bp->b_qindex == QUEUE_NONE); 3085 else 3086 bremfree(bp); 3087 3088 /* 3089 * check for size inconsistencies for non-VMIO case. 3090 */ 3091 if (bp->b_bcount != size) { 3092 if ((bp->b_flags & B_VMIO) == 0 || 3093 (size > bp->b_kvasize)) { 3094 if (bp->b_flags & B_DELWRI) { 3095 /* 3096 * If buffer is pinned and caller does 3097 * not want sleep waiting for it to be 3098 * unpinned, bail out 3099 * */ 3100 if (bp->b_pin_count > 0) { 3101 if (flags & GB_LOCK_NOWAIT) { 3102 bqrelse(bp); 3103 return (NULL); 3104 } else { 3105 bunpin_wait(bp); 3106 } 3107 } 3108 bp->b_flags |= B_NOCACHE; 3109 bwrite(bp); 3110 } else { 3111 if (LIST_EMPTY(&bp->b_dep)) { 3112 bp->b_flags |= B_RELBUF; 3113 brelse(bp); 3114 } else { 3115 bp->b_flags |= B_NOCACHE; 3116 bwrite(bp); 3117 } 3118 } 3119 goto loop; 3120 } 3121 } 3122 3123 /* 3124 * Handle the case of unmapped buffer which should 3125 * become mapped, or the buffer for which KVA 3126 * reservation is requested. 3127 */ 3128 bp_unmapped_get_kva(bp, blkno, size, flags); 3129 3130 /* 3131 * If the size is inconsistant in the VMIO case, we can resize 3132 * the buffer. This might lead to B_CACHE getting set or 3133 * cleared. If the size has not changed, B_CACHE remains 3134 * unchanged from its previous state. 3135 */ 3136 if (bp->b_bcount != size) 3137 allocbuf(bp, size); 3138 3139 KASSERT(bp->b_offset != NOOFFSET, 3140 ("getblk: no buffer offset")); 3141 3142 /* 3143 * A buffer with B_DELWRI set and B_CACHE clear must 3144 * be committed before we can return the buffer in 3145 * order to prevent the caller from issuing a read 3146 * ( due to B_CACHE not being set ) and overwriting 3147 * it. 3148 * 3149 * Most callers, including NFS and FFS, need this to 3150 * operate properly either because they assume they 3151 * can issue a read if B_CACHE is not set, or because 3152 * ( for example ) an uncached B_DELWRI might loop due 3153 * to softupdates re-dirtying the buffer. In the latter 3154 * case, B_CACHE is set after the first write completes, 3155 * preventing further loops. 3156 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 3157 * above while extending the buffer, we cannot allow the 3158 * buffer to remain with B_CACHE set after the write 3159 * completes or it will represent a corrupt state. To 3160 * deal with this we set B_NOCACHE to scrap the buffer 3161 * after the write. 3162 * 3163 * We might be able to do something fancy, like setting 3164 * B_CACHE in bwrite() except if B_DELWRI is already set, 3165 * so the below call doesn't set B_CACHE, but that gets real 3166 * confusing. This is much easier. 3167 */ 3168 3169 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 3170 bp->b_flags |= B_NOCACHE; 3171 bwrite(bp); 3172 goto loop; 3173 } 3174 bp->b_flags &= ~B_DONE; 3175 } else { 3176 /* 3177 * Buffer is not in-core, create new buffer. The buffer 3178 * returned by getnewbuf() is locked. Note that the returned 3179 * buffer is also considered valid (not marked B_INVAL). 3180 */ 3181 BO_RUNLOCK(bo); 3182 /* 3183 * If the user does not want us to create the buffer, bail out 3184 * here. 3185 */ 3186 if (flags & GB_NOCREAT) 3187 return NULL; 3188 if (numfreebuffers == 0 && TD_IS_IDLETHREAD(curthread)) 3189 return NULL; 3190 3191 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize; 3192 offset = blkno * bsize; 3193 vmio = vp->v_object != NULL; 3194 if (vmio) { 3195 maxsize = size + (offset & PAGE_MASK); 3196 } else { 3197 maxsize = size; 3198 /* Do not allow non-VMIO notmapped buffers. */ 3199 flags &= ~GB_UNMAPPED; 3200 } 3201 maxsize = imax(maxsize, bsize); 3202 3203 bp = getnewbuf(vp, slpflag, slptimeo, size, maxsize, flags); 3204 if (bp == NULL) { 3205 if (slpflag || slptimeo) 3206 return NULL; 3207 goto loop; 3208 } 3209 3210 /* 3211 * This code is used to make sure that a buffer is not 3212 * created while the getnewbuf routine is blocked. 3213 * This can be a problem whether the vnode is locked or not. 3214 * If the buffer is created out from under us, we have to 3215 * throw away the one we just created. 3216 * 3217 * Note: this must occur before we associate the buffer 3218 * with the vp especially considering limitations in 3219 * the splay tree implementation when dealing with duplicate 3220 * lblkno's. 3221 */ 3222 BO_LOCK(bo); 3223 if (gbincore(bo, blkno)) { 3224 BO_UNLOCK(bo); 3225 bp->b_flags |= B_INVAL; 3226 brelse(bp); 3227 goto loop; 3228 } 3229 3230 /* 3231 * Insert the buffer into the hash, so that it can 3232 * be found by incore. 3233 */ 3234 bp->b_blkno = bp->b_lblkno = blkno; 3235 bp->b_offset = offset; 3236 bgetvp(vp, bp); 3237 BO_UNLOCK(bo); 3238 3239 /* 3240 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 3241 * buffer size starts out as 0, B_CACHE will be set by 3242 * allocbuf() for the VMIO case prior to it testing the 3243 * backing store for validity. 3244 */ 3245 3246 if (vmio) { 3247 bp->b_flags |= B_VMIO; 3248 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 3249 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 3250 bp, vp->v_object, bp->b_bufobj->bo_object)); 3251 } else { 3252 bp->b_flags &= ~B_VMIO; 3253 KASSERT(bp->b_bufobj->bo_object == NULL, 3254 ("ARGH! has b_bufobj->bo_object %p %p\n", 3255 bp, bp->b_bufobj->bo_object)); 3256 BUF_CHECK_MAPPED(bp); 3257 } 3258 3259 allocbuf(bp, size); 3260 bp->b_flags &= ~B_DONE; 3261 } 3262 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 3263 BUF_ASSERT_HELD(bp); 3264end: 3265 KASSERT(bp->b_bufobj == bo, 3266 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 3267 return (bp); 3268} 3269 3270/* 3271 * Get an empty, disassociated buffer of given size. The buffer is initially 3272 * set to B_INVAL. 3273 */ 3274struct buf * 3275geteblk(int size, int flags) 3276{ 3277 struct buf *bp; 3278 int maxsize; 3279 3280 maxsize = (size + BKVAMASK) & ~BKVAMASK; 3281 while ((bp = getnewbuf(NULL, 0, 0, size, maxsize, flags)) == NULL) { 3282 if ((flags & GB_NOWAIT_BD) && 3283 (curthread->td_pflags & TDP_BUFNEED) != 0) 3284 return (NULL); 3285 } 3286 allocbuf(bp, size); 3287 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 3288 BUF_ASSERT_HELD(bp); 3289 return (bp); 3290} 3291 3292 3293/* 3294 * This code constitutes the buffer memory from either anonymous system 3295 * memory (in the case of non-VMIO operations) or from an associated 3296 * VM object (in the case of VMIO operations). This code is able to 3297 * resize a buffer up or down. 3298 * 3299 * Note that this code is tricky, and has many complications to resolve 3300 * deadlock or inconsistant data situations. Tread lightly!!! 3301 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 3302 * the caller. Calling this code willy nilly can result in the loss of data. 3303 * 3304 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 3305 * B_CACHE for the non-VMIO case. 3306 */ 3307 3308int 3309allocbuf(struct buf *bp, int size) 3310{ 3311 int newbsize, mbsize; 3312 int i; 3313 3314 BUF_ASSERT_HELD(bp); 3315 3316 if (bp->b_kvasize < size) 3317 panic("allocbuf: buffer too small"); 3318 3319 if ((bp->b_flags & B_VMIO) == 0) { 3320 caddr_t origbuf; 3321 int origbufsize; 3322 /* 3323 * Just get anonymous memory from the kernel. Don't 3324 * mess with B_CACHE. 3325 */ 3326 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3327 if (bp->b_flags & B_MALLOC) 3328 newbsize = mbsize; 3329 else 3330 newbsize = round_page(size); 3331 3332 if (newbsize < bp->b_bufsize) { 3333 /* 3334 * malloced buffers are not shrunk 3335 */ 3336 if (bp->b_flags & B_MALLOC) { 3337 if (newbsize) { 3338 bp->b_bcount = size; 3339 } else { 3340 free(bp->b_data, M_BIOBUF); 3341 if (bp->b_bufsize) { 3342 atomic_subtract_long( 3343 &bufmallocspace, 3344 bp->b_bufsize); 3345 bufspacewakeup(); 3346 bp->b_bufsize = 0; 3347 } 3348 bp->b_saveaddr = bp->b_kvabase; 3349 bp->b_data = bp->b_saveaddr; 3350 bp->b_bcount = 0; 3351 bp->b_flags &= ~B_MALLOC; 3352 } 3353 return 1; 3354 } 3355 vm_hold_free_pages(bp, newbsize); 3356 } else if (newbsize > bp->b_bufsize) { 3357 /* 3358 * We only use malloced memory on the first allocation. 3359 * and revert to page-allocated memory when the buffer 3360 * grows. 3361 */ 3362 /* 3363 * There is a potential smp race here that could lead 3364 * to bufmallocspace slightly passing the max. It 3365 * is probably extremely rare and not worth worrying 3366 * over. 3367 */ 3368 if ( (bufmallocspace < maxbufmallocspace) && 3369 (bp->b_bufsize == 0) && 3370 (mbsize <= PAGE_SIZE/2)) { 3371 3372 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 3373 bp->b_bufsize = mbsize; 3374 bp->b_bcount = size; 3375 bp->b_flags |= B_MALLOC; 3376 atomic_add_long(&bufmallocspace, mbsize); 3377 return 1; 3378 } 3379 origbuf = NULL; 3380 origbufsize = 0; 3381 /* 3382 * If the buffer is growing on its other-than-first allocation, 3383 * then we revert to the page-allocation scheme. 3384 */ 3385 if (bp->b_flags & B_MALLOC) { 3386 origbuf = bp->b_data; 3387 origbufsize = bp->b_bufsize; 3388 bp->b_data = bp->b_kvabase; 3389 if (bp->b_bufsize) { 3390 atomic_subtract_long(&bufmallocspace, 3391 bp->b_bufsize); 3392 bufspacewakeup(); 3393 bp->b_bufsize = 0; 3394 } 3395 bp->b_flags &= ~B_MALLOC; 3396 newbsize = round_page(newbsize); 3397 } 3398 vm_hold_load_pages( 3399 bp, 3400 (vm_offset_t) bp->b_data + bp->b_bufsize, 3401 (vm_offset_t) bp->b_data + newbsize); 3402 if (origbuf) { 3403 bcopy(origbuf, bp->b_data, origbufsize); 3404 free(origbuf, M_BIOBUF); 3405 } 3406 } 3407 } else { 3408 int desiredpages; 3409 3410 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3411 desiredpages = (size == 0) ? 0 : 3412 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 3413 3414 if (bp->b_flags & B_MALLOC) 3415 panic("allocbuf: VMIO buffer can't be malloced"); 3416 /* 3417 * Set B_CACHE initially if buffer is 0 length or will become 3418 * 0-length. 3419 */ 3420 if (size == 0 || bp->b_bufsize == 0) 3421 bp->b_flags |= B_CACHE; 3422 3423 if (newbsize < bp->b_bufsize) { 3424 /* 3425 * DEV_BSIZE aligned new buffer size is less then the 3426 * DEV_BSIZE aligned existing buffer size. Figure out 3427 * if we have to remove any pages. 3428 */ 3429 if (desiredpages < bp->b_npages) { 3430 vm_page_t m; 3431 3432 if ((bp->b_flags & B_UNMAPPED) == 0) { 3433 BUF_CHECK_MAPPED(bp); 3434 pmap_qremove((vm_offset_t)trunc_page( 3435 (vm_offset_t)bp->b_data) + 3436 (desiredpages << PAGE_SHIFT), 3437 (bp->b_npages - desiredpages)); 3438 } else 3439 BUF_CHECK_UNMAPPED(bp); 3440 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 3441 for (i = desiredpages; i < bp->b_npages; i++) { 3442 /* 3443 * the page is not freed here -- it 3444 * is the responsibility of 3445 * vnode_pager_setsize 3446 */ 3447 m = bp->b_pages[i]; 3448 KASSERT(m != bogus_page, 3449 ("allocbuf: bogus page found")); 3450 while (vm_page_sleep_if_busy(m, 3451 "biodep")) 3452 continue; 3453 3454 bp->b_pages[i] = NULL; 3455 vm_page_lock(m); 3456 vm_page_unwire(m, 0); 3457 vm_page_unlock(m); 3458 } 3459 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 3460 bp->b_npages = desiredpages; 3461 } 3462 } else if (size > bp->b_bcount) { 3463 /* 3464 * We are growing the buffer, possibly in a 3465 * byte-granular fashion. 3466 */ 3467 vm_object_t obj; 3468 vm_offset_t toff; 3469 vm_offset_t tinc; 3470 3471 /* 3472 * Step 1, bring in the VM pages from the object, 3473 * allocating them if necessary. We must clear 3474 * B_CACHE if these pages are not valid for the 3475 * range covered by the buffer. 3476 */ 3477 3478 obj = bp->b_bufobj->bo_object; 3479 3480 VM_OBJECT_WLOCK(obj); 3481 while (bp->b_npages < desiredpages) { 3482 vm_page_t m; 3483 3484 /* 3485 * We must allocate system pages since blocking 3486 * here could interfere with paging I/O, no 3487 * matter which process we are. 3488 * 3489 * Only exclusive busy can be tested here. 3490 * Blocking on shared busy might lead to 3491 * deadlocks once allocbuf() is called after 3492 * pages are vfs_busy_pages(). 3493 */ 3494 m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) + 3495 bp->b_npages, VM_ALLOC_NOBUSY | 3496 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED | 3497 VM_ALLOC_IGN_SBUSY | 3498 VM_ALLOC_COUNT(desiredpages - bp->b_npages)); 3499 if (m->valid == 0) 3500 bp->b_flags &= ~B_CACHE; 3501 bp->b_pages[bp->b_npages] = m; 3502 ++bp->b_npages; 3503 } 3504 3505 /* 3506 * Step 2. We've loaded the pages into the buffer, 3507 * we have to figure out if we can still have B_CACHE 3508 * set. Note that B_CACHE is set according to the 3509 * byte-granular range ( bcount and size ), new the 3510 * aligned range ( newbsize ). 3511 * 3512 * The VM test is against m->valid, which is DEV_BSIZE 3513 * aligned. Needless to say, the validity of the data 3514 * needs to also be DEV_BSIZE aligned. Note that this 3515 * fails with NFS if the server or some other client 3516 * extends the file's EOF. If our buffer is resized, 3517 * B_CACHE may remain set! XXX 3518 */ 3519 3520 toff = bp->b_bcount; 3521 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 3522 3523 while ((bp->b_flags & B_CACHE) && toff < size) { 3524 vm_pindex_t pi; 3525 3526 if (tinc > (size - toff)) 3527 tinc = size - toff; 3528 3529 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 3530 PAGE_SHIFT; 3531 3532 vfs_buf_test_cache( 3533 bp, 3534 bp->b_offset, 3535 toff, 3536 tinc, 3537 bp->b_pages[pi] 3538 ); 3539 toff += tinc; 3540 tinc = PAGE_SIZE; 3541 } 3542 VM_OBJECT_WUNLOCK(obj); 3543 3544 /* 3545 * Step 3, fixup the KVM pmap. 3546 */ 3547 if ((bp->b_flags & B_UNMAPPED) == 0) 3548 bpmap_qenter(bp); 3549 else 3550 BUF_CHECK_UNMAPPED(bp); 3551 } 3552 } 3553 if (newbsize < bp->b_bufsize) 3554 bufspacewakeup(); 3555 bp->b_bufsize = newbsize; /* actual buffer allocation */ 3556 bp->b_bcount = size; /* requested buffer size */ 3557 return 1; 3558} 3559 3560extern int inflight_transient_maps; 3561 3562void 3563biodone(struct bio *bp) 3564{ 3565 struct mtx *mtxp; 3566 void (*done)(struct bio *); 3567 vm_offset_t start, end; 3568 3569 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) { 3570 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING; 3571 bp->bio_flags |= BIO_UNMAPPED; 3572 start = trunc_page((vm_offset_t)bp->bio_data); 3573 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length); 3574 pmap_qremove(start, OFF_TO_IDX(end - start)); 3575 vmem_free(transient_arena, start, end - start); 3576 atomic_add_int(&inflight_transient_maps, -1); 3577 } 3578 done = bp->bio_done; 3579 if (done == NULL) { 3580 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3581 mtx_lock(mtxp); 3582 bp->bio_flags |= BIO_DONE; 3583 wakeup(bp); 3584 mtx_unlock(mtxp); 3585 } else { 3586 bp->bio_flags |= BIO_DONE; 3587 done(bp); 3588 } 3589} 3590 3591/* 3592 * Wait for a BIO to finish. 3593 */ 3594int 3595biowait(struct bio *bp, const char *wchan) 3596{ 3597 struct mtx *mtxp; 3598 3599 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3600 mtx_lock(mtxp); 3601 while ((bp->bio_flags & BIO_DONE) == 0) 3602 msleep(bp, mtxp, PRIBIO, wchan, 0); 3603 mtx_unlock(mtxp); 3604 if (bp->bio_error != 0) 3605 return (bp->bio_error); 3606 if (!(bp->bio_flags & BIO_ERROR)) 3607 return (0); 3608 return (EIO); 3609} 3610 3611void 3612biofinish(struct bio *bp, struct devstat *stat, int error) 3613{ 3614 3615 if (error) { 3616 bp->bio_error = error; 3617 bp->bio_flags |= BIO_ERROR; 3618 } 3619 if (stat != NULL) 3620 devstat_end_transaction_bio(stat, bp); 3621 biodone(bp); 3622} 3623 3624/* 3625 * bufwait: 3626 * 3627 * Wait for buffer I/O completion, returning error status. The buffer 3628 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3629 * error and cleared. 3630 */ 3631int 3632bufwait(struct buf *bp) 3633{ 3634 if (bp->b_iocmd == BIO_READ) 3635 bwait(bp, PRIBIO, "biord"); 3636 else 3637 bwait(bp, PRIBIO, "biowr"); 3638 if (bp->b_flags & B_EINTR) { 3639 bp->b_flags &= ~B_EINTR; 3640 return (EINTR); 3641 } 3642 if (bp->b_ioflags & BIO_ERROR) { 3643 return (bp->b_error ? bp->b_error : EIO); 3644 } else { 3645 return (0); 3646 } 3647} 3648 3649 /* 3650 * Call back function from struct bio back up to struct buf. 3651 */ 3652static void 3653bufdonebio(struct bio *bip) 3654{ 3655 struct buf *bp; 3656 3657 bp = bip->bio_caller2; 3658 bp->b_resid = bp->b_bcount - bip->bio_completed; 3659 bp->b_resid = bip->bio_resid; /* XXX: remove */ 3660 bp->b_ioflags = bip->bio_flags; 3661 bp->b_error = bip->bio_error; 3662 if (bp->b_error) 3663 bp->b_ioflags |= BIO_ERROR; 3664 bufdone(bp); 3665 g_destroy_bio(bip); 3666} 3667 3668void 3669dev_strategy(struct cdev *dev, struct buf *bp) 3670{ 3671 struct cdevsw *csw; 3672 int ref; 3673 3674 KASSERT(dev->si_refcount > 0, 3675 ("dev_strategy on un-referenced struct cdev *(%s) %p", 3676 devtoname(dev), dev)); 3677 3678 csw = dev_refthread(dev, &ref); 3679 dev_strategy_csw(dev, csw, bp); 3680 dev_relthread(dev, ref); 3681} 3682 3683void 3684dev_strategy_csw(struct cdev *dev, struct cdevsw *csw, struct buf *bp) 3685{ 3686 struct bio *bip; 3687 3688 KASSERT(bp->b_iocmd == BIO_READ || bp->b_iocmd == BIO_WRITE, 3689 ("b_iocmd botch")); 3690 KASSERT(((dev->si_flags & SI_ETERNAL) != 0 && csw != NULL) || 3691 dev->si_threadcount > 0, 3692 ("dev_strategy_csw threadcount cdev *(%s) %p", devtoname(dev), 3693 dev)); 3694 if (csw == NULL) { 3695 bp->b_error = ENXIO; 3696 bp->b_ioflags = BIO_ERROR; 3697 bufdone(bp); 3698 return; 3699 } 3700 for (;;) { 3701 bip = g_new_bio(); 3702 if (bip != NULL) 3703 break; 3704 /* Try again later */ 3705 tsleep(&bp, PRIBIO, "dev_strat", hz/10); 3706 } 3707 bip->bio_cmd = bp->b_iocmd; 3708 bip->bio_offset = bp->b_iooffset; 3709 bip->bio_length = bp->b_bcount; 3710 bip->bio_bcount = bp->b_bcount; /* XXX: remove */ 3711 bdata2bio(bp, bip); 3712 bip->bio_done = bufdonebio; 3713 bip->bio_caller2 = bp; 3714 bip->bio_dev = dev; 3715 (*csw->d_strategy)(bip); 3716} 3717 3718/* 3719 * bufdone: 3720 * 3721 * Finish I/O on a buffer, optionally calling a completion function. 3722 * This is usually called from an interrupt so process blocking is 3723 * not allowed. 3724 * 3725 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3726 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3727 * assuming B_INVAL is clear. 3728 * 3729 * For the VMIO case, we set B_CACHE if the op was a read and no 3730 * read error occured, or if the op was a write. B_CACHE is never 3731 * set if the buffer is invalid or otherwise uncacheable. 3732 * 3733 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3734 * initiator to leave B_INVAL set to brelse the buffer out of existance 3735 * in the biodone routine. 3736 */ 3737void 3738bufdone(struct buf *bp) 3739{ 3740 struct bufobj *dropobj; 3741 void (*biodone)(struct buf *); 3742 3743 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 3744 dropobj = NULL; 3745 3746 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 3747 BUF_ASSERT_HELD(bp); 3748 3749 runningbufwakeup(bp); 3750 if (bp->b_iocmd == BIO_WRITE) 3751 dropobj = bp->b_bufobj; 3752 /* call optional completion function if requested */ 3753 if (bp->b_iodone != NULL) { 3754 biodone = bp->b_iodone; 3755 bp->b_iodone = NULL; 3756 (*biodone) (bp); 3757 if (dropobj) 3758 bufobj_wdrop(dropobj); 3759 return; 3760 } 3761 3762 bufdone_finish(bp); 3763 3764 if (dropobj) 3765 bufobj_wdrop(dropobj); 3766} 3767 3768void 3769bufdone_finish(struct buf *bp) 3770{ 3771 BUF_ASSERT_HELD(bp); 3772 3773 if (!LIST_EMPTY(&bp->b_dep)) 3774 buf_complete(bp); 3775 3776 if (bp->b_flags & B_VMIO) { 3777 vm_ooffset_t foff; 3778 vm_page_t m; 3779 vm_object_t obj; 3780 struct vnode *vp; 3781 int bogus, i, iosize; 3782 3783 obj = bp->b_bufobj->bo_object; 3784 KASSERT(obj->paging_in_progress >= bp->b_npages, 3785 ("biodone_finish: paging in progress(%d) < b_npages(%d)", 3786 obj->paging_in_progress, bp->b_npages)); 3787 3788 vp = bp->b_vp; 3789 KASSERT(vp->v_holdcnt > 0, 3790 ("biodone_finish: vnode %p has zero hold count", vp)); 3791 KASSERT(vp->v_object != NULL, 3792 ("biodone_finish: vnode %p has no vm_object", vp)); 3793 3794 foff = bp->b_offset; 3795 KASSERT(bp->b_offset != NOOFFSET, 3796 ("biodone_finish: bp %p has no buffer offset", bp)); 3797 3798 /* 3799 * Set B_CACHE if the op was a normal read and no error 3800 * occured. B_CACHE is set for writes in the b*write() 3801 * routines. 3802 */ 3803 iosize = bp->b_bcount - bp->b_resid; 3804 if (bp->b_iocmd == BIO_READ && 3805 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 3806 !(bp->b_ioflags & BIO_ERROR)) { 3807 bp->b_flags |= B_CACHE; 3808 } 3809 bogus = 0; 3810 VM_OBJECT_WLOCK(obj); 3811 for (i = 0; i < bp->b_npages; i++) { 3812 int bogusflag = 0; 3813 int resid; 3814 3815 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 3816 if (resid > iosize) 3817 resid = iosize; 3818 3819 /* 3820 * cleanup bogus pages, restoring the originals 3821 */ 3822 m = bp->b_pages[i]; 3823 if (m == bogus_page) { 3824 bogus = bogusflag = 1; 3825 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3826 if (m == NULL) 3827 panic("biodone: page disappeared!"); 3828 bp->b_pages[i] = m; 3829 } 3830 KASSERT(OFF_TO_IDX(foff) == m->pindex, 3831 ("biodone_finish: foff(%jd)/pindex(%ju) mismatch", 3832 (intmax_t)foff, (uintmax_t)m->pindex)); 3833 3834 /* 3835 * In the write case, the valid and clean bits are 3836 * already changed correctly ( see bdwrite() ), so we 3837 * only need to do this here in the read case. 3838 */ 3839 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 3840 KASSERT((m->dirty & vm_page_bits(foff & 3841 PAGE_MASK, resid)) == 0, ("bufdone_finish:" 3842 " page %p has unexpected dirty bits", m)); 3843 vfs_page_set_valid(bp, foff, m); 3844 } 3845 3846 vm_page_sunbusy(m); 3847 vm_object_pip_subtract(obj, 1); 3848 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3849 iosize -= resid; 3850 } 3851 vm_object_pip_wakeupn(obj, 0); 3852 VM_OBJECT_WUNLOCK(obj); 3853 if (bogus && (bp->b_flags & B_UNMAPPED) == 0) { 3854 BUF_CHECK_MAPPED(bp); 3855 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3856 bp->b_pages, bp->b_npages); 3857 } 3858 } 3859 3860 /* 3861 * For asynchronous completions, release the buffer now. The brelse 3862 * will do a wakeup there if necessary - so no need to do a wakeup 3863 * here in the async case. The sync case always needs to do a wakeup. 3864 */ 3865 3866 if (bp->b_flags & B_ASYNC) { 3867 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 3868 brelse(bp); 3869 else 3870 bqrelse(bp); 3871 } else 3872 bdone(bp); 3873} 3874 3875/* 3876 * This routine is called in lieu of iodone in the case of 3877 * incomplete I/O. This keeps the busy status for pages 3878 * consistant. 3879 */ 3880void 3881vfs_unbusy_pages(struct buf *bp) 3882{ 3883 int i; 3884 vm_object_t obj; 3885 vm_page_t m; 3886 3887 runningbufwakeup(bp); 3888 if (!(bp->b_flags & B_VMIO)) 3889 return; 3890 3891 obj = bp->b_bufobj->bo_object; 3892 VM_OBJECT_WLOCK(obj); 3893 for (i = 0; i < bp->b_npages; i++) { 3894 m = bp->b_pages[i]; 3895 if (m == bogus_page) { 3896 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 3897 if (!m) 3898 panic("vfs_unbusy_pages: page missing\n"); 3899 bp->b_pages[i] = m; 3900 if ((bp->b_flags & B_UNMAPPED) == 0) { 3901 BUF_CHECK_MAPPED(bp); 3902 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3903 bp->b_pages, bp->b_npages); 3904 } else 3905 BUF_CHECK_UNMAPPED(bp); 3906 } 3907 vm_object_pip_subtract(obj, 1); 3908 vm_page_sunbusy(m); 3909 } 3910 vm_object_pip_wakeupn(obj, 0); 3911 VM_OBJECT_WUNLOCK(obj); 3912} 3913 3914/* 3915 * vfs_page_set_valid: 3916 * 3917 * Set the valid bits in a page based on the supplied offset. The 3918 * range is restricted to the buffer's size. 3919 * 3920 * This routine is typically called after a read completes. 3921 */ 3922static void 3923vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3924{ 3925 vm_ooffset_t eoff; 3926 3927 /* 3928 * Compute the end offset, eoff, such that [off, eoff) does not span a 3929 * page boundary and eoff is not greater than the end of the buffer. 3930 * The end of the buffer, in this case, is our file EOF, not the 3931 * allocation size of the buffer. 3932 */ 3933 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 3934 if (eoff > bp->b_offset + bp->b_bcount) 3935 eoff = bp->b_offset + bp->b_bcount; 3936 3937 /* 3938 * Set valid range. This is typically the entire buffer and thus the 3939 * entire page. 3940 */ 3941 if (eoff > off) 3942 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off); 3943} 3944 3945/* 3946 * vfs_page_set_validclean: 3947 * 3948 * Set the valid bits and clear the dirty bits in a page based on the 3949 * supplied offset. The range is restricted to the buffer's size. 3950 */ 3951static void 3952vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3953{ 3954 vm_ooffset_t soff, eoff; 3955 3956 /* 3957 * Start and end offsets in buffer. eoff - soff may not cross a 3958 * page boundry or cross the end of the buffer. The end of the 3959 * buffer, in this case, is our file EOF, not the allocation size 3960 * of the buffer. 3961 */ 3962 soff = off; 3963 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3964 if (eoff > bp->b_offset + bp->b_bcount) 3965 eoff = bp->b_offset + bp->b_bcount; 3966 3967 /* 3968 * Set valid range. This is typically the entire buffer and thus the 3969 * entire page. 3970 */ 3971 if (eoff > soff) { 3972 vm_page_set_validclean( 3973 m, 3974 (vm_offset_t) (soff & PAGE_MASK), 3975 (vm_offset_t) (eoff - soff) 3976 ); 3977 } 3978} 3979 3980/* 3981 * Ensure that all buffer pages are not exclusive busied. If any page is 3982 * exclusive busy, drain it. 3983 */ 3984void 3985vfs_drain_busy_pages(struct buf *bp) 3986{ 3987 vm_page_t m; 3988 int i, last_busied; 3989 3990 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object); 3991 last_busied = 0; 3992 for (i = 0; i < bp->b_npages; i++) { 3993 m = bp->b_pages[i]; 3994 if (vm_page_xbusied(m)) { 3995 for (; last_busied < i; last_busied++) 3996 vm_page_sbusy(bp->b_pages[last_busied]); 3997 while (vm_page_xbusied(m)) { 3998 vm_page_lock(m); 3999 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4000 vm_page_busy_sleep(m, "vbpage"); 4001 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4002 } 4003 } 4004 } 4005 for (i = 0; i < last_busied; i++) 4006 vm_page_sunbusy(bp->b_pages[i]); 4007} 4008 4009/* 4010 * This routine is called before a device strategy routine. 4011 * It is used to tell the VM system that paging I/O is in 4012 * progress, and treat the pages associated with the buffer 4013 * almost as being exclusive busy. Also the object paging_in_progress 4014 * flag is handled to make sure that the object doesn't become 4015 * inconsistant. 4016 * 4017 * Since I/O has not been initiated yet, certain buffer flags 4018 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 4019 * and should be ignored. 4020 */ 4021void 4022vfs_busy_pages(struct buf *bp, int clear_modify) 4023{ 4024 int i, bogus; 4025 vm_object_t obj; 4026 vm_ooffset_t foff; 4027 vm_page_t m; 4028 4029 if (!(bp->b_flags & B_VMIO)) 4030 return; 4031 4032 obj = bp->b_bufobj->bo_object; 4033 foff = bp->b_offset; 4034 KASSERT(bp->b_offset != NOOFFSET, 4035 ("vfs_busy_pages: no buffer offset")); 4036 VM_OBJECT_WLOCK(obj); 4037 vfs_drain_busy_pages(bp); 4038 if (bp->b_bufsize != 0) 4039 vfs_setdirty_locked_object(bp); 4040 bogus = 0; 4041 for (i = 0; i < bp->b_npages; i++) { 4042 m = bp->b_pages[i]; 4043 4044 if ((bp->b_flags & B_CLUSTER) == 0) { 4045 vm_object_pip_add(obj, 1); 4046 vm_page_sbusy(m); 4047 } 4048 /* 4049 * When readying a buffer for a read ( i.e 4050 * clear_modify == 0 ), it is important to do 4051 * bogus_page replacement for valid pages in 4052 * partially instantiated buffers. Partially 4053 * instantiated buffers can, in turn, occur when 4054 * reconstituting a buffer from its VM backing store 4055 * base. We only have to do this if B_CACHE is 4056 * clear ( which causes the I/O to occur in the 4057 * first place ). The replacement prevents the read 4058 * I/O from overwriting potentially dirty VM-backed 4059 * pages. XXX bogus page replacement is, uh, bogus. 4060 * It may not work properly with small-block devices. 4061 * We need to find a better way. 4062 */ 4063 if (clear_modify) { 4064 pmap_remove_write(m); 4065 vfs_page_set_validclean(bp, foff, m); 4066 } else if (m->valid == VM_PAGE_BITS_ALL && 4067 (bp->b_flags & B_CACHE) == 0) { 4068 bp->b_pages[i] = bogus_page; 4069 bogus++; 4070 } 4071 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4072 } 4073 VM_OBJECT_WUNLOCK(obj); 4074 if (bogus && (bp->b_flags & B_UNMAPPED) == 0) { 4075 BUF_CHECK_MAPPED(bp); 4076 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4077 bp->b_pages, bp->b_npages); 4078 } 4079} 4080 4081/* 4082 * vfs_bio_set_valid: 4083 * 4084 * Set the range within the buffer to valid. The range is 4085 * relative to the beginning of the buffer, b_offset. Note that 4086 * b_offset itself may be offset from the beginning of the first 4087 * page. 4088 */ 4089void 4090vfs_bio_set_valid(struct buf *bp, int base, int size) 4091{ 4092 int i, n; 4093 vm_page_t m; 4094 4095 if (!(bp->b_flags & B_VMIO)) 4096 return; 4097 4098 /* 4099 * Fixup base to be relative to beginning of first page. 4100 * Set initial n to be the maximum number of bytes in the 4101 * first page that can be validated. 4102 */ 4103 base += (bp->b_offset & PAGE_MASK); 4104 n = PAGE_SIZE - (base & PAGE_MASK); 4105 4106 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4107 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4108 m = bp->b_pages[i]; 4109 if (n > size) 4110 n = size; 4111 vm_page_set_valid_range(m, base & PAGE_MASK, n); 4112 base += n; 4113 size -= n; 4114 n = PAGE_SIZE; 4115 } 4116 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4117} 4118 4119/* 4120 * vfs_bio_clrbuf: 4121 * 4122 * If the specified buffer is a non-VMIO buffer, clear the entire 4123 * buffer. If the specified buffer is a VMIO buffer, clear and 4124 * validate only the previously invalid portions of the buffer. 4125 * This routine essentially fakes an I/O, so we need to clear 4126 * BIO_ERROR and B_INVAL. 4127 * 4128 * Note that while we only theoretically need to clear through b_bcount, 4129 * we go ahead and clear through b_bufsize. 4130 */ 4131void 4132vfs_bio_clrbuf(struct buf *bp) 4133{ 4134 int i, j, mask, sa, ea, slide; 4135 4136 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 4137 clrbuf(bp); 4138 return; 4139 } 4140 bp->b_flags &= ~B_INVAL; 4141 bp->b_ioflags &= ~BIO_ERROR; 4142 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4143 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 4144 (bp->b_offset & PAGE_MASK) == 0) { 4145 if (bp->b_pages[0] == bogus_page) 4146 goto unlock; 4147 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 4148 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object); 4149 if ((bp->b_pages[0]->valid & mask) == mask) 4150 goto unlock; 4151 if ((bp->b_pages[0]->valid & mask) == 0) { 4152 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize); 4153 bp->b_pages[0]->valid |= mask; 4154 goto unlock; 4155 } 4156 } 4157 sa = bp->b_offset & PAGE_MASK; 4158 slide = 0; 4159 for (i = 0; i < bp->b_npages; i++, sa = 0) { 4160 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize); 4161 ea = slide & PAGE_MASK; 4162 if (ea == 0) 4163 ea = PAGE_SIZE; 4164 if (bp->b_pages[i] == bogus_page) 4165 continue; 4166 j = sa / DEV_BSIZE; 4167 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 4168 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object); 4169 if ((bp->b_pages[i]->valid & mask) == mask) 4170 continue; 4171 if ((bp->b_pages[i]->valid & mask) == 0) 4172 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa); 4173 else { 4174 for (; sa < ea; sa += DEV_BSIZE, j++) { 4175 if ((bp->b_pages[i]->valid & (1 << j)) == 0) { 4176 pmap_zero_page_area(bp->b_pages[i], 4177 sa, DEV_BSIZE); 4178 } 4179 } 4180 } 4181 bp->b_pages[i]->valid |= mask; 4182 } 4183unlock: 4184 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4185 bp->b_resid = 0; 4186} 4187 4188void 4189vfs_bio_bzero_buf(struct buf *bp, int base, int size) 4190{ 4191 vm_page_t m; 4192 int i, n; 4193 4194 if ((bp->b_flags & B_UNMAPPED) == 0) { 4195 BUF_CHECK_MAPPED(bp); 4196 bzero(bp->b_data + base, size); 4197 } else { 4198 BUF_CHECK_UNMAPPED(bp); 4199 n = PAGE_SIZE - (base & PAGE_MASK); 4200 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4201 m = bp->b_pages[i]; 4202 if (n > size) 4203 n = size; 4204 pmap_zero_page_area(m, base & PAGE_MASK, n); 4205 base += n; 4206 size -= n; 4207 n = PAGE_SIZE; 4208 } 4209 } 4210} 4211 4212/* 4213 * vm_hold_load_pages and vm_hold_free_pages get pages into 4214 * a buffers address space. The pages are anonymous and are 4215 * not associated with a file object. 4216 */ 4217static void 4218vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4219{ 4220 vm_offset_t pg; 4221 vm_page_t p; 4222 int index; 4223 4224 BUF_CHECK_MAPPED(bp); 4225 4226 to = round_page(to); 4227 from = round_page(from); 4228 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4229 4230 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 4231tryagain: 4232 /* 4233 * note: must allocate system pages since blocking here 4234 * could interfere with paging I/O, no matter which 4235 * process we are. 4236 */ 4237 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ | 4238 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT)); 4239 if (p == NULL) { 4240 VM_WAIT; 4241 goto tryagain; 4242 } 4243 pmap_qenter(pg, &p, 1); 4244 bp->b_pages[index] = p; 4245 } 4246 bp->b_npages = index; 4247} 4248 4249/* Return pages associated with this buf to the vm system */ 4250static void 4251vm_hold_free_pages(struct buf *bp, int newbsize) 4252{ 4253 vm_offset_t from; 4254 vm_page_t p; 4255 int index, newnpages; 4256 4257 BUF_CHECK_MAPPED(bp); 4258 4259 from = round_page((vm_offset_t)bp->b_data + newbsize); 4260 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4261 if (bp->b_npages > newnpages) 4262 pmap_qremove(from, bp->b_npages - newnpages); 4263 for (index = newnpages; index < bp->b_npages; index++) { 4264 p = bp->b_pages[index]; 4265 bp->b_pages[index] = NULL; 4266 if (vm_page_sbusied(p)) 4267 printf("vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 4268 (intmax_t)bp->b_blkno, (intmax_t)bp->b_lblkno); 4269 p->wire_count--; 4270 vm_page_free(p); 4271 atomic_subtract_int(&cnt.v_wire_count, 1); 4272 } 4273 bp->b_npages = newnpages; 4274} 4275 4276/* 4277 * Map an IO request into kernel virtual address space. 4278 * 4279 * All requests are (re)mapped into kernel VA space. 4280 * Notice that we use b_bufsize for the size of the buffer 4281 * to be mapped. b_bcount might be modified by the driver. 4282 * 4283 * Note that even if the caller determines that the address space should 4284 * be valid, a race or a smaller-file mapped into a larger space may 4285 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 4286 * check the return value. 4287 */ 4288int 4289vmapbuf(struct buf *bp, int mapbuf) 4290{ 4291 caddr_t kva; 4292 vm_prot_t prot; 4293 int pidx; 4294 4295 if (bp->b_bufsize < 0) 4296 return (-1); 4297 prot = VM_PROT_READ; 4298 if (bp->b_iocmd == BIO_READ) 4299 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 4300 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 4301 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages, 4302 btoc(MAXPHYS))) < 0) 4303 return (-1); 4304 bp->b_npages = pidx; 4305 if (mapbuf || !unmapped_buf_allowed) { 4306 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx); 4307 kva = bp->b_saveaddr; 4308 bp->b_saveaddr = bp->b_data; 4309 bp->b_data = kva + (((vm_offset_t)bp->b_data) & PAGE_MASK); 4310 bp->b_flags &= ~B_UNMAPPED; 4311 } else { 4312 bp->b_flags |= B_UNMAPPED; 4313 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK; 4314 bp->b_saveaddr = bp->b_data; 4315 bp->b_data = unmapped_buf; 4316 } 4317 return(0); 4318} 4319 4320/* 4321 * Free the io map PTEs associated with this IO operation. 4322 * We also invalidate the TLB entries and restore the original b_addr. 4323 */ 4324void 4325vunmapbuf(struct buf *bp) 4326{ 4327 int npages; 4328 4329 npages = bp->b_npages; 4330 if (bp->b_flags & B_UNMAPPED) 4331 bp->b_flags &= ~B_UNMAPPED; 4332 else 4333 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 4334 vm_page_unhold_pages(bp->b_pages, npages); 4335 4336 bp->b_data = bp->b_saveaddr; 4337} 4338 4339void 4340bdone(struct buf *bp) 4341{ 4342 struct mtx *mtxp; 4343 4344 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4345 mtx_lock(mtxp); 4346 bp->b_flags |= B_DONE; 4347 wakeup(bp); 4348 mtx_unlock(mtxp); 4349} 4350 4351void 4352bwait(struct buf *bp, u_char pri, const char *wchan) 4353{ 4354 struct mtx *mtxp; 4355 4356 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4357 mtx_lock(mtxp); 4358 while ((bp->b_flags & B_DONE) == 0) 4359 msleep(bp, mtxp, pri, wchan, 0); 4360 mtx_unlock(mtxp); 4361} 4362 4363int 4364bufsync(struct bufobj *bo, int waitfor) 4365{ 4366 4367 return (VOP_FSYNC(bo->__bo_vnode, waitfor, curthread)); 4368} 4369 4370void 4371bufstrategy(struct bufobj *bo, struct buf *bp) 4372{ 4373 int i = 0; 4374 struct vnode *vp; 4375 4376 vp = bp->b_vp; 4377 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 4378 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 4379 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 4380 i = VOP_STRATEGY(vp, bp); 4381 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 4382} 4383 4384void 4385bufobj_wrefl(struct bufobj *bo) 4386{ 4387 4388 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4389 ASSERT_BO_WLOCKED(bo); 4390 bo->bo_numoutput++; 4391} 4392 4393void 4394bufobj_wref(struct bufobj *bo) 4395{ 4396 4397 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4398 BO_LOCK(bo); 4399 bo->bo_numoutput++; 4400 BO_UNLOCK(bo); 4401} 4402 4403void 4404bufobj_wdrop(struct bufobj *bo) 4405{ 4406 4407 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 4408 BO_LOCK(bo); 4409 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 4410 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 4411 bo->bo_flag &= ~BO_WWAIT; 4412 wakeup(&bo->bo_numoutput); 4413 } 4414 BO_UNLOCK(bo); 4415} 4416 4417int 4418bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 4419{ 4420 int error; 4421 4422 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 4423 ASSERT_BO_WLOCKED(bo); 4424 error = 0; 4425 while (bo->bo_numoutput) { 4426 bo->bo_flag |= BO_WWAIT; 4427 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo), 4428 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 4429 if (error) 4430 break; 4431 } 4432 return (error); 4433} 4434 4435void 4436bpin(struct buf *bp) 4437{ 4438 struct mtx *mtxp; 4439 4440 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4441 mtx_lock(mtxp); 4442 bp->b_pin_count++; 4443 mtx_unlock(mtxp); 4444} 4445 4446void 4447bunpin(struct buf *bp) 4448{ 4449 struct mtx *mtxp; 4450 4451 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4452 mtx_lock(mtxp); 4453 if (--bp->b_pin_count == 0) 4454 wakeup(bp); 4455 mtx_unlock(mtxp); 4456} 4457 4458void 4459bunpin_wait(struct buf *bp) 4460{ 4461 struct mtx *mtxp; 4462 4463 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4464 mtx_lock(mtxp); 4465 while (bp->b_pin_count > 0) 4466 msleep(bp, mtxp, PRIBIO, "bwunpin", 0); 4467 mtx_unlock(mtxp); 4468} 4469 4470/* 4471 * Set bio_data or bio_ma for struct bio from the struct buf. 4472 */ 4473void 4474bdata2bio(struct buf *bp, struct bio *bip) 4475{ 4476 4477 if ((bp->b_flags & B_UNMAPPED) != 0) { 4478 KASSERT(unmapped_buf_allowed, ("unmapped")); 4479 bip->bio_ma = bp->b_pages; 4480 bip->bio_ma_n = bp->b_npages; 4481 bip->bio_data = unmapped_buf; 4482 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 4483 bip->bio_flags |= BIO_UNMAPPED; 4484 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) / 4485 PAGE_SIZE == bp->b_npages, 4486 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset, 4487 (long long)bip->bio_length, bip->bio_ma_n)); 4488 } else { 4489 bip->bio_data = bp->b_data; 4490 bip->bio_ma = NULL; 4491 } 4492} 4493 4494#include "opt_ddb.h" 4495#ifdef DDB 4496#include <ddb/ddb.h> 4497 4498/* DDB command to show buffer data */ 4499DB_SHOW_COMMAND(buffer, db_show_buffer) 4500{ 4501 /* get args */ 4502 struct buf *bp = (struct buf *)addr; 4503 4504 if (!have_addr) { 4505 db_printf("usage: show buffer <addr>\n"); 4506 return; 4507 } 4508 4509 db_printf("buf at %p\n", bp); 4510 db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n", 4511 (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags, 4512 PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS); 4513 db_printf( 4514 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 4515 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, " 4516 "b_dep = %p\n", 4517 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 4518 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 4519 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first); 4520 if (bp->b_npages) { 4521 int i; 4522 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 4523 for (i = 0; i < bp->b_npages; i++) { 4524 vm_page_t m; 4525 m = bp->b_pages[i]; 4526 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 4527 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 4528 if ((i + 1) < bp->b_npages) 4529 db_printf(","); 4530 } 4531 db_printf("\n"); 4532 } 4533 db_printf(" "); 4534 BUF_LOCKPRINTINFO(bp); 4535} 4536 4537DB_SHOW_COMMAND(lockedbufs, lockedbufs) 4538{ 4539 struct buf *bp; 4540 int i; 4541 4542 for (i = 0; i < nbuf; i++) { 4543 bp = &buf[i]; 4544 if (BUF_ISLOCKED(bp)) { 4545 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4546 db_printf("\n"); 4547 } 4548 } 4549} 4550 4551DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 4552{ 4553 struct vnode *vp; 4554 struct buf *bp; 4555 4556 if (!have_addr) { 4557 db_printf("usage: show vnodebufs <addr>\n"); 4558 return; 4559 } 4560 vp = (struct vnode *)addr; 4561 db_printf("Clean buffers:\n"); 4562 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 4563 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4564 db_printf("\n"); 4565 } 4566 db_printf("Dirty buffers:\n"); 4567 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 4568 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4569 db_printf("\n"); 4570 } 4571} 4572 4573DB_COMMAND(countfreebufs, db_coundfreebufs) 4574{ 4575 struct buf *bp; 4576 int i, used = 0, nfree = 0; 4577 4578 if (have_addr) { 4579 db_printf("usage: countfreebufs\n"); 4580 return; 4581 } 4582 4583 for (i = 0; i < nbuf; i++) { 4584 bp = &buf[i]; 4585 if ((bp->b_flags & B_INFREECNT) != 0) 4586 nfree++; 4587 else 4588 used++; 4589 } 4590 4591 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 4592 nfree + used); 4593 db_printf("numfreebuffers is %d\n", numfreebuffers); 4594} 4595#endif /* DDB */ 4596