vfs_bio.c revision 282411
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 282411 2015-05-04 08:16:32Z kib $"); 47 48#include <sys/param.h> 49#include <sys/systm.h> 50#include <sys/bio.h> 51#include <sys/conf.h> 52#include <sys/buf.h> 53#include <sys/devicestat.h> 54#include <sys/eventhandler.h> 55#include <sys/fail.h> 56#include <sys/limits.h> 57#include <sys/lock.h> 58#include <sys/malloc.h> 59#include <sys/mount.h> 60#include <sys/mutex.h> 61#include <sys/kernel.h> 62#include <sys/kthread.h> 63#include <sys/proc.h> 64#include <sys/resourcevar.h> 65#include <sys/rwlock.h> 66#include <sys/sysctl.h> 67#include <sys/vmem.h> 68#include <sys/vmmeter.h> 69#include <sys/vnode.h> 70#include <geom/geom.h> 71#include <vm/vm.h> 72#include <vm/vm_param.h> 73#include <vm/vm_kern.h> 74#include <vm/vm_pageout.h> 75#include <vm/vm_page.h> 76#include <vm/vm_object.h> 77#include <vm/vm_extern.h> 78#include <vm/vm_map.h> 79#include "opt_compat.h" 80#include "opt_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(struct vnode *vp, int); 117static int flushbufqueues(struct vnode *, int, int); 118static void buf_daemon(void); 119static void bremfreel(struct buf *bp); 120static __inline void bd_wakeup(void); 121#if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 122 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 123static int sysctl_bufspace(SYSCTL_HANDLER_ARGS); 124#endif 125 126int vmiodirenable = TRUE; 127SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, 128 "Use the VM system for directory writes"); 129long runningbufspace; 130SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 131 "Amount of presently outstanding async buffer io"); 132static long bufspace; 133#if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 134 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 135SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD, 136 &bufspace, 0, sysctl_bufspace, "L", "Virtual memory used for buffers"); 137#else 138SYSCTL_LONG(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, 139 "Virtual memory used for buffers"); 140#endif 141static long unmapped_bufspace; 142SYSCTL_LONG(_vfs, OID_AUTO, unmapped_bufspace, CTLFLAG_RD, 143 &unmapped_bufspace, 0, 144 "Amount of unmapped buffers, inclusive in the bufspace"); 145static long maxbufspace; 146SYSCTL_LONG(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0, 147 "Maximum allowed value of bufspace (including buf_daemon)"); 148static long bufmallocspace; 149SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 150 "Amount of malloced memory for buffers"); 151static long maxbufmallocspace; 152SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0, 153 "Maximum amount of malloced memory for buffers"); 154static long lobufspace; 155SYSCTL_LONG(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0, 156 "Minimum amount of buffers we want to have"); 157long hibufspace; 158SYSCTL_LONG(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0, 159 "Maximum allowed value of bufspace (excluding buf_daemon)"); 160static int bufreusecnt; 161SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0, 162 "Number of times we have reused a buffer"); 163static int buffreekvacnt; 164SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0, 165 "Number of times we have freed the KVA space from some buffer"); 166static int bufdefragcnt; 167SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0, 168 "Number of times we have had to repeat buffer allocation to defragment"); 169static long lorunningspace; 170SYSCTL_LONG(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0, 171 "Minimum preferred space used for in-progress I/O"); 172static long hirunningspace; 173SYSCTL_LONG(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0, 174 "Maximum amount of space to use for in-progress I/O"); 175int dirtybufferflushes; 176SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes, 177 0, "Number of bdwrite to bawrite conversions to limit dirty buffers"); 178int bdwriteskip; 179SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip, 180 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk"); 181int altbufferflushes; 182SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes, 183 0, "Number of fsync flushes to limit dirty buffers"); 184static int recursiveflushes; 185SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes, 186 0, "Number of flushes skipped due to being recursive"); 187static int numdirtybuffers; 188SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0, 189 "Number of buffers that are dirty (has unwritten changes) at the moment"); 190static int lodirtybuffers; 191SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0, 192 "How many buffers we want to have free before bufdaemon can sleep"); 193static int hidirtybuffers; 194SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0, 195 "When the number of dirty buffers is considered severe"); 196int dirtybufthresh; 197SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh, 198 0, "Number of bdwrite to bawrite conversions to clear dirty buffers"); 199static int numfreebuffers; 200SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, 201 "Number of free buffers"); 202static int lofreebuffers; 203SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0, 204 "XXX Unused"); 205static int hifreebuffers; 206SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0, 207 "XXX Complicatedly unused"); 208static int getnewbufcalls; 209SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0, 210 "Number of calls to getnewbuf"); 211static int getnewbufrestarts; 212SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0, 213 "Number of times getnewbuf has had to restart a buffer aquisition"); 214static int mappingrestarts; 215SYSCTL_INT(_vfs, OID_AUTO, mappingrestarts, CTLFLAG_RW, &mappingrestarts, 0, 216 "Number of times getblk has had to restart a buffer mapping for " 217 "unmapped buffer"); 218static int flushbufqtarget = 100; 219SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0, 220 "Amount of work to do in flushbufqueues when helping bufdaemon"); 221static long notbufdflushes; 222SYSCTL_LONG(_vfs, OID_AUTO, notbufdflushes, CTLFLAG_RD, ¬bufdflushes, 0, 223 "Number of dirty buffer flushes done by the bufdaemon helpers"); 224static long barrierwrites; 225SYSCTL_LONG(_vfs, OID_AUTO, barrierwrites, CTLFLAG_RW, &barrierwrites, 0, 226 "Number of barrier writes"); 227SYSCTL_INT(_vfs, OID_AUTO, unmapped_buf_allowed, CTLFLAG_RD, 228 &unmapped_buf_allowed, 0, 229 "Permit the use of the unmapped i/o"); 230 231/* 232 * Lock for the non-dirty bufqueues 233 */ 234static struct mtx_padalign bqclean; 235 236/* 237 * Lock for the dirty queue. 238 */ 239static struct mtx_padalign bqdirty; 240 241/* 242 * This lock synchronizes access to bd_request. 243 */ 244static struct mtx_padalign bdlock; 245 246/* 247 * This lock protects the runningbufreq and synchronizes runningbufwakeup and 248 * waitrunningbufspace(). 249 */ 250static struct mtx_padalign rbreqlock; 251 252/* 253 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it. 254 */ 255static struct 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#ifndef NSWBUF_MIN 640#define NSWBUF_MIN 16 641#endif 642 643#ifdef __i386__ 644#define TRANSIENT_DENOM 5 645#else 646#define TRANSIENT_DENOM 10 647#endif 648 649/* 650 * Calculating buffer cache scaling values and reserve space for buffer 651 * headers. This is called during low level kernel initialization and 652 * may be called more then once. We CANNOT write to the memory area 653 * being reserved at this time. 654 */ 655caddr_t 656kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 657{ 658 int tuned_nbuf; 659 long maxbuf, maxbuf_sz, buf_sz, biotmap_sz; 660 661 /* 662 * physmem_est is in pages. Convert it to kilobytes (assumes 663 * PAGE_SIZE is >= 1K) 664 */ 665 physmem_est = physmem_est * (PAGE_SIZE / 1024); 666 667 /* 668 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 669 * For the first 64MB of ram nominally allocate sufficient buffers to 670 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 671 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing 672 * the buffer cache we limit the eventual kva reservation to 673 * maxbcache bytes. 674 * 675 * factor represents the 1/4 x ram conversion. 676 */ 677 if (nbuf == 0) { 678 int factor = 4 * BKVASIZE / 1024; 679 680 nbuf = 50; 681 if (physmem_est > 4096) 682 nbuf += min((physmem_est - 4096) / factor, 683 65536 / factor); 684 if (physmem_est > 65536) 685 nbuf += min((physmem_est - 65536) * 2 / (factor * 5), 686 32 * 1024 * 1024 / (factor * 5)); 687 688 if (maxbcache && nbuf > maxbcache / BKVASIZE) 689 nbuf = maxbcache / BKVASIZE; 690 tuned_nbuf = 1; 691 } else 692 tuned_nbuf = 0; 693 694 /* XXX Avoid unsigned long overflows later on with maxbufspace. */ 695 maxbuf = (LONG_MAX / 3) / BKVASIZE; 696 if (nbuf > maxbuf) { 697 if (!tuned_nbuf) 698 printf("Warning: nbufs lowered from %d to %ld\n", nbuf, 699 maxbuf); 700 nbuf = maxbuf; 701 } 702 703 /* 704 * Ideal allocation size for the transient bio submap if 10% 705 * of the maximal space buffer map. This roughly corresponds 706 * to the amount of the buffer mapped for typical UFS load. 707 * 708 * Clip the buffer map to reserve space for the transient 709 * BIOs, if its extent is bigger than 90% (80% on i386) of the 710 * maximum buffer map extent on the platform. 711 * 712 * The fall-back to the maxbuf in case of maxbcache unset, 713 * allows to not trim the buffer KVA for the architectures 714 * with ample KVA space. 715 */ 716 if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) { 717 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE; 718 buf_sz = (long)nbuf * BKVASIZE; 719 if (buf_sz < maxbuf_sz / TRANSIENT_DENOM * 720 (TRANSIENT_DENOM - 1)) { 721 /* 722 * There is more KVA than memory. Do not 723 * adjust buffer map size, and assign the rest 724 * of maxbuf to transient map. 725 */ 726 biotmap_sz = maxbuf_sz - buf_sz; 727 } else { 728 /* 729 * Buffer map spans all KVA we could afford on 730 * this platform. Give 10% (20% on i386) of 731 * the buffer map to the transient bio map. 732 */ 733 biotmap_sz = buf_sz / TRANSIENT_DENOM; 734 buf_sz -= biotmap_sz; 735 } 736 if (biotmap_sz / INT_MAX > MAXPHYS) 737 bio_transient_maxcnt = INT_MAX; 738 else 739 bio_transient_maxcnt = biotmap_sz / MAXPHYS; 740 /* 741 * Artifically limit to 1024 simultaneous in-flight I/Os 742 * using the transient mapping. 743 */ 744 if (bio_transient_maxcnt > 1024) 745 bio_transient_maxcnt = 1024; 746 if (tuned_nbuf) 747 nbuf = buf_sz / BKVASIZE; 748 } 749 750 /* 751 * swbufs are used as temporary holders for I/O, such as paging I/O. 752 * We have no less then 16 and no more then 256. 753 */ 754 nswbuf = min(nbuf / 4, 256); 755 TUNABLE_INT_FETCH("kern.nswbuf", &nswbuf); 756 if (nswbuf < NSWBUF_MIN) 757 nswbuf = NSWBUF_MIN; 758 759 /* 760 * Reserve space for the buffer cache buffers 761 */ 762 swbuf = (void *)v; 763 v = (caddr_t)(swbuf + nswbuf); 764 buf = (void *)v; 765 v = (caddr_t)(buf + nbuf); 766 767 return(v); 768} 769 770/* Initialize the buffer subsystem. Called before use of any buffers. */ 771void 772bufinit(void) 773{ 774 struct buf *bp; 775 int i; 776 777 mtx_init(&bqclean, "bufq clean lock", NULL, MTX_DEF); 778 mtx_init(&bqdirty, "bufq dirty lock", NULL, MTX_DEF); 779 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 780 rw_init(&nblock, "needsbuffer lock"); 781 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 782 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF); 783 784 /* next, make a null set of free lists */ 785 for (i = 0; i < BUFFER_QUEUES; i++) 786 TAILQ_INIT(&bufqueues[i]); 787 788 /* finally, initialize each buffer header and stick on empty q */ 789 for (i = 0; i < nbuf; i++) { 790 bp = &buf[i]; 791 bzero(bp, sizeof *bp); 792 bp->b_flags = B_INVAL | B_INFREECNT; 793 bp->b_rcred = NOCRED; 794 bp->b_wcred = NOCRED; 795 bp->b_qindex = QUEUE_EMPTY; 796 bp->b_xflags = 0; 797 LIST_INIT(&bp->b_dep); 798 BUF_LOCKINIT(bp); 799 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 800#ifdef INVARIANTS 801 bq_len[QUEUE_EMPTY]++; 802#endif 803 } 804 805 /* 806 * maxbufspace is the absolute maximum amount of buffer space we are 807 * allowed to reserve in KVM and in real terms. The absolute maximum 808 * is nominally used by buf_daemon. hibufspace is the nominal maximum 809 * used by most other processes. The differential is required to 810 * ensure that buf_daemon is able to run when other processes might 811 * be blocked waiting for buffer space. 812 * 813 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 814 * this may result in KVM fragmentation which is not handled optimally 815 * by the system. 816 */ 817 maxbufspace = (long)nbuf * BKVASIZE; 818 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 819 lobufspace = hibufspace - MAXBSIZE; 820 821 /* 822 * Note: The 16 MiB upper limit for hirunningspace was chosen 823 * arbitrarily and may need further tuning. It corresponds to 824 * 128 outstanding write IO requests (if IO size is 128 KiB), 825 * which fits with many RAID controllers' tagged queuing limits. 826 * The lower 1 MiB limit is the historical upper limit for 827 * hirunningspace. 828 */ 829 hirunningspace = lmax(lmin(roundup(hibufspace / 64, MAXBSIZE), 830 16 * 1024 * 1024), 1024 * 1024); 831 lorunningspace = roundup((hirunningspace * 2) / 3, MAXBSIZE); 832 833/* 834 * Limit the amount of malloc memory since it is wired permanently into 835 * the kernel space. Even though this is accounted for in the buffer 836 * allocation, we don't want the malloced region to grow uncontrolled. 837 * The malloc scheme improves memory utilization significantly on average 838 * (small) directories. 839 */ 840 maxbufmallocspace = hibufspace / 20; 841 842/* 843 * Reduce the chance of a deadlock occuring by limiting the number 844 * of delayed-write dirty buffers we allow to stack up. 845 */ 846 hidirtybuffers = nbuf / 4 + 20; 847 dirtybufthresh = hidirtybuffers * 9 / 10; 848 numdirtybuffers = 0; 849/* 850 * To support extreme low-memory systems, make sure hidirtybuffers cannot 851 * eat up all available buffer space. This occurs when our minimum cannot 852 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 853 * BKVASIZE'd buffers. 854 */ 855 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 856 hidirtybuffers >>= 1; 857 } 858 lodirtybuffers = hidirtybuffers / 2; 859 860/* 861 * Try to keep the number of free buffers in the specified range, 862 * and give special processes (e.g. like buf_daemon) access to an 863 * emergency reserve. 864 */ 865 lofreebuffers = nbuf / 18 + 5; 866 hifreebuffers = 2 * lofreebuffers; 867 numfreebuffers = nbuf; 868 869 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ | 870 VM_ALLOC_NORMAL | VM_ALLOC_WIRED); 871 unmapped_buf = (caddr_t)kva_alloc(MAXPHYS); 872} 873 874#ifdef INVARIANTS 875static inline void 876vfs_buf_check_mapped(struct buf *bp) 877{ 878 879 KASSERT((bp->b_flags & B_UNMAPPED) == 0, 880 ("mapped buf %p %x", bp, bp->b_flags)); 881 KASSERT(bp->b_kvabase != unmapped_buf, 882 ("mapped buf: b_kvabase was not updated %p", bp)); 883 KASSERT(bp->b_data != unmapped_buf, 884 ("mapped buf: b_data was not updated %p", bp)); 885} 886 887static inline void 888vfs_buf_check_unmapped(struct buf *bp) 889{ 890 891 KASSERT((bp->b_flags & B_UNMAPPED) == B_UNMAPPED, 892 ("unmapped buf %p %x", bp, bp->b_flags)); 893 KASSERT(bp->b_kvabase == unmapped_buf, 894 ("unmapped buf: corrupted b_kvabase %p", bp)); 895 KASSERT(bp->b_data == unmapped_buf, 896 ("unmapped buf: corrupted b_data %p", bp)); 897} 898 899#define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp) 900#define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp) 901#else 902#define BUF_CHECK_MAPPED(bp) do {} while (0) 903#define BUF_CHECK_UNMAPPED(bp) do {} while (0) 904#endif 905 906static void 907bpmap_qenter(struct buf *bp) 908{ 909 910 BUF_CHECK_MAPPED(bp); 911 912 /* 913 * bp->b_data is relative to bp->b_offset, but 914 * bp->b_offset may be offset into the first page. 915 */ 916 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data); 917 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages); 918 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 919 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 920} 921 922/* 923 * bfreekva() - free the kva allocation for a buffer. 924 * 925 * Since this call frees up buffer space, we call bufspacewakeup(). 926 */ 927static void 928bfreekva(struct buf *bp) 929{ 930 931 if (bp->b_kvasize == 0) 932 return; 933 934 atomic_add_int(&buffreekvacnt, 1); 935 atomic_subtract_long(&bufspace, bp->b_kvasize); 936 if ((bp->b_flags & B_UNMAPPED) == 0) { 937 BUF_CHECK_MAPPED(bp); 938 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, 939 bp->b_kvasize); 940 } else { 941 BUF_CHECK_UNMAPPED(bp); 942 if ((bp->b_flags & B_KVAALLOC) != 0) { 943 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvaalloc, 944 bp->b_kvasize); 945 } 946 atomic_subtract_long(&unmapped_bufspace, bp->b_kvasize); 947 bp->b_flags &= ~(B_UNMAPPED | B_KVAALLOC); 948 } 949 bp->b_kvasize = 0; 950 bufspacewakeup(); 951} 952 953/* 954 * binsfree: 955 * 956 * Insert the buffer into the appropriate free list. 957 */ 958static void 959binsfree(struct buf *bp, int qindex) 960{ 961 struct mtx *olock, *nlock; 962 963 BUF_ASSERT_XLOCKED(bp); 964 965 olock = bqlock(bp->b_qindex); 966 nlock = bqlock(qindex); 967 mtx_lock(olock); 968 /* Handle delayed bremfree() processing. */ 969 if (bp->b_flags & B_REMFREE) 970 bremfreel(bp); 971 972 if (bp->b_qindex != QUEUE_NONE) 973 panic("binsfree: free buffer onto another queue???"); 974 975 bp->b_qindex = qindex; 976 if (olock != nlock) { 977 mtx_unlock(olock); 978 mtx_lock(nlock); 979 } 980 if (bp->b_flags & B_AGE) 981 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 982 else 983 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 984#ifdef INVARIANTS 985 bq_len[bp->b_qindex]++; 986#endif 987 mtx_unlock(nlock); 988 989 /* 990 * Something we can maybe free or reuse. 991 */ 992 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 993 bufspacewakeup(); 994 995 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI)) 996 bufcountadd(bp); 997} 998 999/* 1000 * bremfree: 1001 * 1002 * Mark the buffer for removal from the appropriate free list. 1003 * 1004 */ 1005void 1006bremfree(struct buf *bp) 1007{ 1008 1009 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1010 KASSERT((bp->b_flags & B_REMFREE) == 0, 1011 ("bremfree: buffer %p already marked for delayed removal.", bp)); 1012 KASSERT(bp->b_qindex != QUEUE_NONE, 1013 ("bremfree: buffer %p not on a queue.", bp)); 1014 BUF_ASSERT_XLOCKED(bp); 1015 1016 bp->b_flags |= B_REMFREE; 1017 bufcountsub(bp); 1018} 1019 1020/* 1021 * bremfreef: 1022 * 1023 * Force an immediate removal from a free list. Used only in nfs when 1024 * it abuses the b_freelist pointer. 1025 */ 1026void 1027bremfreef(struct buf *bp) 1028{ 1029 struct mtx *qlock; 1030 1031 qlock = bqlock(bp->b_qindex); 1032 mtx_lock(qlock); 1033 bremfreel(bp); 1034 mtx_unlock(qlock); 1035} 1036 1037/* 1038 * bremfreel: 1039 * 1040 * Removes a buffer from the free list, must be called with the 1041 * correct qlock held. 1042 */ 1043static void 1044bremfreel(struct buf *bp) 1045{ 1046 1047 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X", 1048 bp, bp->b_vp, bp->b_flags); 1049 KASSERT(bp->b_qindex != QUEUE_NONE, 1050 ("bremfreel: buffer %p not on a queue.", bp)); 1051 BUF_ASSERT_XLOCKED(bp); 1052 mtx_assert(bqlock(bp->b_qindex), MA_OWNED); 1053 1054 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 1055#ifdef INVARIANTS 1056 KASSERT(bq_len[bp->b_qindex] >= 1, ("queue %d underflow", 1057 bp->b_qindex)); 1058 bq_len[bp->b_qindex]--; 1059#endif 1060 bp->b_qindex = QUEUE_NONE; 1061 /* 1062 * If this was a delayed bremfree() we only need to remove the buffer 1063 * from the queue and return the stats are already done. 1064 */ 1065 if (bp->b_flags & B_REMFREE) { 1066 bp->b_flags &= ~B_REMFREE; 1067 return; 1068 } 1069 bufcountsub(bp); 1070} 1071 1072/* 1073 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 1074 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 1075 * the buffer is valid and we do not have to do anything. 1076 */ 1077void 1078breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, 1079 int cnt, struct ucred * cred) 1080{ 1081 struct buf *rabp; 1082 int i; 1083 1084 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 1085 if (inmem(vp, *rablkno)) 1086 continue; 1087 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 1088 1089 if ((rabp->b_flags & B_CACHE) == 0) { 1090 if (!TD_IS_IDLETHREAD(curthread)) 1091 curthread->td_ru.ru_inblock++; 1092 rabp->b_flags |= B_ASYNC; 1093 rabp->b_flags &= ~B_INVAL; 1094 rabp->b_ioflags &= ~BIO_ERROR; 1095 rabp->b_iocmd = BIO_READ; 1096 if (rabp->b_rcred == NOCRED && cred != NOCRED) 1097 rabp->b_rcred = crhold(cred); 1098 vfs_busy_pages(rabp, 0); 1099 BUF_KERNPROC(rabp); 1100 rabp->b_iooffset = dbtob(rabp->b_blkno); 1101 bstrategy(rabp); 1102 } else { 1103 brelse(rabp); 1104 } 1105 } 1106} 1107 1108/* 1109 * Entry point for bread() and breadn() via #defines in sys/buf.h. 1110 * 1111 * Get a buffer with the specified data. Look in the cache first. We 1112 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 1113 * is set, the buffer is valid and we do not have to do anything, see 1114 * getblk(). Also starts asynchronous I/O on read-ahead blocks. 1115 */ 1116int 1117breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno, 1118 int *rabsize, int cnt, struct ucred *cred, int flags, struct buf **bpp) 1119{ 1120 struct buf *bp; 1121 int rv = 0, readwait = 0; 1122 1123 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 1124 /* 1125 * Can only return NULL if GB_LOCK_NOWAIT flag is specified. 1126 */ 1127 *bpp = bp = getblk(vp, blkno, size, 0, 0, flags); 1128 if (bp == NULL) 1129 return (EBUSY); 1130 1131 /* if not found in cache, do some I/O */ 1132 if ((bp->b_flags & B_CACHE) == 0) { 1133 if (!TD_IS_IDLETHREAD(curthread)) 1134 curthread->td_ru.ru_inblock++; 1135 bp->b_iocmd = BIO_READ; 1136 bp->b_flags &= ~B_INVAL; 1137 bp->b_ioflags &= ~BIO_ERROR; 1138 if (bp->b_rcred == NOCRED && cred != NOCRED) 1139 bp->b_rcred = crhold(cred); 1140 vfs_busy_pages(bp, 0); 1141 bp->b_iooffset = dbtob(bp->b_blkno); 1142 bstrategy(bp); 1143 ++readwait; 1144 } 1145 1146 breada(vp, rablkno, rabsize, cnt, cred); 1147 1148 if (readwait) { 1149 rv = bufwait(bp); 1150 } 1151 return (rv); 1152} 1153 1154/* 1155 * Write, release buffer on completion. (Done by iodone 1156 * if async). Do not bother writing anything if the buffer 1157 * is invalid. 1158 * 1159 * Note that we set B_CACHE here, indicating that buffer is 1160 * fully valid and thus cacheable. This is true even of NFS 1161 * now so we set it generally. This could be set either here 1162 * or in biodone() since the I/O is synchronous. We put it 1163 * here. 1164 */ 1165int 1166bufwrite(struct buf *bp) 1167{ 1168 int oldflags; 1169 struct vnode *vp; 1170 long space; 1171 int vp_md; 1172 1173 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1174 if (bp->b_flags & B_INVAL) { 1175 brelse(bp); 1176 return (0); 1177 } 1178 1179 if (bp->b_flags & B_BARRIER) 1180 barrierwrites++; 1181 1182 oldflags = bp->b_flags; 1183 1184 BUF_ASSERT_HELD(bp); 1185 1186 if (bp->b_pin_count > 0) 1187 bunpin_wait(bp); 1188 1189 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 1190 ("FFS background buffer should not get here %p", bp)); 1191 1192 vp = bp->b_vp; 1193 if (vp) 1194 vp_md = vp->v_vflag & VV_MD; 1195 else 1196 vp_md = 0; 1197 1198 /* 1199 * Mark the buffer clean. Increment the bufobj write count 1200 * before bundirty() call, to prevent other thread from seeing 1201 * empty dirty list and zero counter for writes in progress, 1202 * falsely indicating that the bufobj is clean. 1203 */ 1204 bufobj_wref(bp->b_bufobj); 1205 bundirty(bp); 1206 1207 bp->b_flags &= ~B_DONE; 1208 bp->b_ioflags &= ~BIO_ERROR; 1209 bp->b_flags |= B_CACHE; 1210 bp->b_iocmd = BIO_WRITE; 1211 1212 vfs_busy_pages(bp, 1); 1213 1214 /* 1215 * Normal bwrites pipeline writes 1216 */ 1217 bp->b_runningbufspace = bp->b_bufsize; 1218 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace); 1219 1220 if (!TD_IS_IDLETHREAD(curthread)) 1221 curthread->td_ru.ru_oublock++; 1222 if (oldflags & B_ASYNC) 1223 BUF_KERNPROC(bp); 1224 bp->b_iooffset = dbtob(bp->b_blkno); 1225 bstrategy(bp); 1226 1227 if ((oldflags & B_ASYNC) == 0) { 1228 int rtval = bufwait(bp); 1229 brelse(bp); 1230 return (rtval); 1231 } else if (space > hirunningspace) { 1232 /* 1233 * don't allow the async write to saturate the I/O 1234 * system. We will not deadlock here because 1235 * we are blocking waiting for I/O that is already in-progress 1236 * to complete. We do not block here if it is the update 1237 * or syncer daemon trying to clean up as that can lead 1238 * to deadlock. 1239 */ 1240 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 1241 waitrunningbufspace(); 1242 } 1243 1244 return (0); 1245} 1246 1247void 1248bufbdflush(struct bufobj *bo, struct buf *bp) 1249{ 1250 struct buf *nbp; 1251 1252 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 1253 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 1254 altbufferflushes++; 1255 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 1256 BO_LOCK(bo); 1257 /* 1258 * Try to find a buffer to flush. 1259 */ 1260 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 1261 if ((nbp->b_vflags & BV_BKGRDINPROG) || 1262 BUF_LOCK(nbp, 1263 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 1264 continue; 1265 if (bp == nbp) 1266 panic("bdwrite: found ourselves"); 1267 BO_UNLOCK(bo); 1268 /* Don't countdeps with the bo lock held. */ 1269 if (buf_countdeps(nbp, 0)) { 1270 BO_LOCK(bo); 1271 BUF_UNLOCK(nbp); 1272 continue; 1273 } 1274 if (nbp->b_flags & B_CLUSTEROK) { 1275 vfs_bio_awrite(nbp); 1276 } else { 1277 bremfree(nbp); 1278 bawrite(nbp); 1279 } 1280 dirtybufferflushes++; 1281 break; 1282 } 1283 if (nbp == NULL) 1284 BO_UNLOCK(bo); 1285 } 1286} 1287 1288/* 1289 * Delayed write. (Buffer is marked dirty). Do not bother writing 1290 * anything if the buffer is marked invalid. 1291 * 1292 * Note that since the buffer must be completely valid, we can safely 1293 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 1294 * biodone() in order to prevent getblk from writing the buffer 1295 * out synchronously. 1296 */ 1297void 1298bdwrite(struct buf *bp) 1299{ 1300 struct thread *td = curthread; 1301 struct vnode *vp; 1302 struct bufobj *bo; 1303 1304 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1305 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1306 KASSERT((bp->b_flags & B_BARRIER) == 0, 1307 ("Barrier request in delayed write %p", bp)); 1308 BUF_ASSERT_HELD(bp); 1309 1310 if (bp->b_flags & B_INVAL) { 1311 brelse(bp); 1312 return; 1313 } 1314 1315 /* 1316 * If we have too many dirty buffers, don't create any more. 1317 * If we are wildly over our limit, then force a complete 1318 * cleanup. Otherwise, just keep the situation from getting 1319 * out of control. Note that we have to avoid a recursive 1320 * disaster and not try to clean up after our own cleanup! 1321 */ 1322 vp = bp->b_vp; 1323 bo = bp->b_bufobj; 1324 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 1325 td->td_pflags |= TDP_INBDFLUSH; 1326 BO_BDFLUSH(bo, bp); 1327 td->td_pflags &= ~TDP_INBDFLUSH; 1328 } else 1329 recursiveflushes++; 1330 1331 bdirty(bp); 1332 /* 1333 * Set B_CACHE, indicating that the buffer is fully valid. This is 1334 * true even of NFS now. 1335 */ 1336 bp->b_flags |= B_CACHE; 1337 1338 /* 1339 * This bmap keeps the system from needing to do the bmap later, 1340 * perhaps when the system is attempting to do a sync. Since it 1341 * is likely that the indirect block -- or whatever other datastructure 1342 * that the filesystem needs is still in memory now, it is a good 1343 * thing to do this. Note also, that if the pageout daemon is 1344 * requesting a sync -- there might not be enough memory to do 1345 * the bmap then... So, this is important to do. 1346 */ 1347 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 1348 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 1349 } 1350 1351 /* 1352 * Set the *dirty* buffer range based upon the VM system dirty 1353 * pages. 1354 * 1355 * Mark the buffer pages as clean. We need to do this here to 1356 * satisfy the vnode_pager and the pageout daemon, so that it 1357 * thinks that the pages have been "cleaned". Note that since 1358 * the pages are in a delayed write buffer -- the VFS layer 1359 * "will" see that the pages get written out on the next sync, 1360 * or perhaps the cluster will be completed. 1361 */ 1362 vfs_clean_pages_dirty_buf(bp); 1363 bqrelse(bp); 1364 1365 /* 1366 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 1367 * due to the softdep code. 1368 */ 1369} 1370 1371/* 1372 * bdirty: 1373 * 1374 * Turn buffer into delayed write request. We must clear BIO_READ and 1375 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 1376 * itself to properly update it in the dirty/clean lists. We mark it 1377 * B_DONE to ensure that any asynchronization of the buffer properly 1378 * clears B_DONE ( else a panic will occur later ). 1379 * 1380 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 1381 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 1382 * should only be called if the buffer is known-good. 1383 * 1384 * Since the buffer is not on a queue, we do not update the numfreebuffers 1385 * count. 1386 * 1387 * The buffer must be on QUEUE_NONE. 1388 */ 1389void 1390bdirty(struct buf *bp) 1391{ 1392 1393 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 1394 bp, bp->b_vp, bp->b_flags); 1395 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1396 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1397 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1398 BUF_ASSERT_HELD(bp); 1399 bp->b_flags &= ~(B_RELBUF); 1400 bp->b_iocmd = BIO_WRITE; 1401 1402 if ((bp->b_flags & B_DELWRI) == 0) { 1403 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 1404 reassignbuf(bp); 1405 bdirtyadd(); 1406 } 1407} 1408 1409/* 1410 * bundirty: 1411 * 1412 * Clear B_DELWRI for buffer. 1413 * 1414 * Since the buffer is not on a queue, we do not update the numfreebuffers 1415 * count. 1416 * 1417 * The buffer must be on QUEUE_NONE. 1418 */ 1419 1420void 1421bundirty(struct buf *bp) 1422{ 1423 1424 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1425 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1426 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1427 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1428 BUF_ASSERT_HELD(bp); 1429 1430 if (bp->b_flags & B_DELWRI) { 1431 bp->b_flags &= ~B_DELWRI; 1432 reassignbuf(bp); 1433 bdirtysub(); 1434 } 1435 /* 1436 * Since it is now being written, we can clear its deferred write flag. 1437 */ 1438 bp->b_flags &= ~B_DEFERRED; 1439} 1440 1441/* 1442 * bawrite: 1443 * 1444 * Asynchronous write. Start output on a buffer, but do not wait for 1445 * it to complete. The buffer is released when the output completes. 1446 * 1447 * bwrite() ( or the VOP routine anyway ) is responsible for handling 1448 * B_INVAL buffers. Not us. 1449 */ 1450void 1451bawrite(struct buf *bp) 1452{ 1453 1454 bp->b_flags |= B_ASYNC; 1455 (void) bwrite(bp); 1456} 1457 1458/* 1459 * babarrierwrite: 1460 * 1461 * Asynchronous barrier write. Start output on a buffer, but do not 1462 * wait for it to complete. Place a write barrier after this write so 1463 * that this buffer and all buffers written before it are committed to 1464 * the disk before any buffers written after this write are committed 1465 * to the disk. The buffer is released when the output completes. 1466 */ 1467void 1468babarrierwrite(struct buf *bp) 1469{ 1470 1471 bp->b_flags |= B_ASYNC | B_BARRIER; 1472 (void) bwrite(bp); 1473} 1474 1475/* 1476 * bbarrierwrite: 1477 * 1478 * Synchronous barrier write. Start output on a buffer and wait for 1479 * it to complete. Place a write barrier after this write so that 1480 * this buffer and all buffers written before it are committed to 1481 * the disk before any buffers written after this write are committed 1482 * to the disk. The buffer is released when the output completes. 1483 */ 1484int 1485bbarrierwrite(struct buf *bp) 1486{ 1487 1488 bp->b_flags |= B_BARRIER; 1489 return (bwrite(bp)); 1490} 1491 1492/* 1493 * bwillwrite: 1494 * 1495 * Called prior to the locking of any vnodes when we are expecting to 1496 * write. We do not want to starve the buffer cache with too many 1497 * dirty buffers so we block here. By blocking prior to the locking 1498 * of any vnodes we attempt to avoid the situation where a locked vnode 1499 * prevents the various system daemons from flushing related buffers. 1500 */ 1501void 1502bwillwrite(void) 1503{ 1504 1505 if (numdirtybuffers >= hidirtybuffers) { 1506 mtx_lock(&bdirtylock); 1507 while (numdirtybuffers >= hidirtybuffers) { 1508 bdirtywait = 1; 1509 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4), 1510 "flswai", 0); 1511 } 1512 mtx_unlock(&bdirtylock); 1513 } 1514} 1515 1516/* 1517 * Return true if we have too many dirty buffers. 1518 */ 1519int 1520buf_dirty_count_severe(void) 1521{ 1522 1523 return(numdirtybuffers >= hidirtybuffers); 1524} 1525 1526static __noinline int 1527buf_vm_page_count_severe(void) 1528{ 1529 1530 KFAIL_POINT_CODE(DEBUG_FP, buf_pressure, return 1); 1531 1532 return vm_page_count_severe(); 1533} 1534 1535/* 1536 * brelse: 1537 * 1538 * Release a busy buffer and, if requested, free its resources. The 1539 * buffer will be stashed in the appropriate bufqueue[] allowing it 1540 * to be accessed later as a cache entity or reused for other purposes. 1541 */ 1542void 1543brelse(struct buf *bp) 1544{ 1545 int qindex; 1546 1547 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 1548 bp, bp->b_vp, bp->b_flags); 1549 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1550 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1551 1552 if (BUF_LOCKRECURSED(bp)) { 1553 /* 1554 * Do not process, in particular, do not handle the 1555 * B_INVAL/B_RELBUF and do not release to free list. 1556 */ 1557 BUF_UNLOCK(bp); 1558 return; 1559 } 1560 1561 if (bp->b_flags & B_MANAGED) { 1562 bqrelse(bp); 1563 return; 1564 } 1565 1566 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 1567 bp->b_error == EIO && !(bp->b_flags & B_INVAL)) { 1568 /* 1569 * Failed write, redirty. Must clear BIO_ERROR to prevent 1570 * pages from being scrapped. If the error is anything 1571 * other than an I/O error (EIO), assume that retrying 1572 * is futile. 1573 */ 1574 bp->b_ioflags &= ~BIO_ERROR; 1575 bdirty(bp); 1576 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 1577 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 1578 /* 1579 * Either a failed I/O or we were asked to free or not 1580 * cache the buffer. 1581 */ 1582 bp->b_flags |= B_INVAL; 1583 if (!LIST_EMPTY(&bp->b_dep)) 1584 buf_deallocate(bp); 1585 if (bp->b_flags & B_DELWRI) 1586 bdirtysub(); 1587 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1588 if ((bp->b_flags & B_VMIO) == 0) { 1589 if (bp->b_bufsize) 1590 allocbuf(bp, 0); 1591 if (bp->b_vp) 1592 brelvp(bp); 1593 } 1594 } 1595 1596 /* 1597 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1598 * is called with B_DELWRI set, the underlying pages may wind up 1599 * getting freed causing a previous write (bdwrite()) to get 'lost' 1600 * because pages associated with a B_DELWRI bp are marked clean. 1601 * 1602 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1603 * if B_DELWRI is set. 1604 * 1605 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1606 * on pages to return pages to the VM page queues. 1607 */ 1608 if (bp->b_flags & B_DELWRI) 1609 bp->b_flags &= ~B_RELBUF; 1610 else if (buf_vm_page_count_severe()) { 1611 /* 1612 * BKGRDINPROG can only be set with the buf and bufobj 1613 * locks both held. We tolerate a race to clear it here. 1614 */ 1615 if (!(bp->b_vflags & BV_BKGRDINPROG)) 1616 bp->b_flags |= B_RELBUF; 1617 } 1618 1619 /* 1620 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1621 * constituted, not even NFS buffers now. Two flags effect this. If 1622 * B_INVAL, the struct buf is invalidated but the VM object is kept 1623 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1624 * 1625 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 1626 * invalidated. BIO_ERROR cannot be set for a failed write unless the 1627 * buffer is also B_INVAL because it hits the re-dirtying code above. 1628 * 1629 * Normally we can do this whether a buffer is B_DELWRI or not. If 1630 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1631 * the commit state and we cannot afford to lose the buffer. If the 1632 * buffer has a background write in progress, we need to keep it 1633 * around to prevent it from being reconstituted and starting a second 1634 * background write. 1635 */ 1636 if ((bp->b_flags & B_VMIO) 1637 && !(bp->b_vp->v_mount != NULL && 1638 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 1639 !vn_isdisk(bp->b_vp, NULL) && 1640 (bp->b_flags & B_DELWRI)) 1641 ) { 1642 1643 int i, j, resid; 1644 vm_page_t m; 1645 off_t foff; 1646 vm_pindex_t poff; 1647 vm_object_t obj; 1648 1649 obj = bp->b_bufobj->bo_object; 1650 1651 /* 1652 * Get the base offset and length of the buffer. Note that 1653 * in the VMIO case if the buffer block size is not 1654 * page-aligned then b_data pointer may not be page-aligned. 1655 * But our b_pages[] array *IS* page aligned. 1656 * 1657 * block sizes less then DEV_BSIZE (usually 512) are not 1658 * supported due to the page granularity bits (m->valid, 1659 * m->dirty, etc...). 1660 * 1661 * See man buf(9) for more information 1662 */ 1663 resid = bp->b_bufsize; 1664 foff = bp->b_offset; 1665 for (i = 0; i < bp->b_npages; i++) { 1666 int had_bogus = 0; 1667 1668 m = bp->b_pages[i]; 1669 1670 /* 1671 * If we hit a bogus page, fixup *all* the bogus pages 1672 * now. 1673 */ 1674 if (m == bogus_page) { 1675 poff = OFF_TO_IDX(bp->b_offset); 1676 had_bogus = 1; 1677 1678 VM_OBJECT_RLOCK(obj); 1679 for (j = i; j < bp->b_npages; j++) { 1680 vm_page_t mtmp; 1681 mtmp = bp->b_pages[j]; 1682 if (mtmp == bogus_page) { 1683 mtmp = vm_page_lookup(obj, poff + j); 1684 if (!mtmp) { 1685 panic("brelse: page missing\n"); 1686 } 1687 bp->b_pages[j] = mtmp; 1688 } 1689 } 1690 VM_OBJECT_RUNLOCK(obj); 1691 1692 if ((bp->b_flags & (B_INVAL | B_UNMAPPED)) == 0) { 1693 BUF_CHECK_MAPPED(bp); 1694 pmap_qenter( 1695 trunc_page((vm_offset_t)bp->b_data), 1696 bp->b_pages, bp->b_npages); 1697 } 1698 m = bp->b_pages[i]; 1699 } 1700 if ((bp->b_flags & B_NOCACHE) || 1701 (bp->b_ioflags & BIO_ERROR && 1702 bp->b_iocmd == BIO_READ)) { 1703 int poffset = foff & PAGE_MASK; 1704 int presid = resid > (PAGE_SIZE - poffset) ? 1705 (PAGE_SIZE - poffset) : resid; 1706 1707 KASSERT(presid >= 0, ("brelse: extra page")); 1708 VM_OBJECT_WLOCK(obj); 1709 while (vm_page_xbusied(m)) { 1710 vm_page_lock(m); 1711 VM_OBJECT_WUNLOCK(obj); 1712 vm_page_busy_sleep(m, "mbncsh"); 1713 VM_OBJECT_WLOCK(obj); 1714 } 1715 if (pmap_page_wired_mappings(m) == 0) 1716 vm_page_set_invalid(m, poffset, presid); 1717 VM_OBJECT_WUNLOCK(obj); 1718 if (had_bogus) 1719 printf("avoided corruption bug in bogus_page/brelse code\n"); 1720 } 1721 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1722 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1723 } 1724 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1725 vfs_vmio_release(bp); 1726 1727 } else if (bp->b_flags & B_VMIO) { 1728 1729 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1730 vfs_vmio_release(bp); 1731 } 1732 1733 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) { 1734 if (bp->b_bufsize != 0) 1735 allocbuf(bp, 0); 1736 if (bp->b_vp != NULL) 1737 brelvp(bp); 1738 } 1739 1740 /* 1741 * If the buffer has junk contents signal it and eventually 1742 * clean up B_DELWRI and diassociate the vnode so that gbincore() 1743 * doesn't find it. 1744 */ 1745 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 1746 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 1747 bp->b_flags |= B_INVAL; 1748 if (bp->b_flags & B_INVAL) { 1749 if (bp->b_flags & B_DELWRI) 1750 bundirty(bp); 1751 if (bp->b_vp) 1752 brelvp(bp); 1753 } 1754 1755 /* buffers with no memory */ 1756 if (bp->b_bufsize == 0) { 1757 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1758 if (bp->b_vflags & BV_BKGRDINPROG) 1759 panic("losing buffer 1"); 1760 if (bp->b_kvasize) 1761 qindex = QUEUE_EMPTYKVA; 1762 else 1763 qindex = QUEUE_EMPTY; 1764 bp->b_flags |= B_AGE; 1765 /* buffers with junk contents */ 1766 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 1767 (bp->b_ioflags & BIO_ERROR)) { 1768 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1769 if (bp->b_vflags & BV_BKGRDINPROG) 1770 panic("losing buffer 2"); 1771 qindex = QUEUE_CLEAN; 1772 bp->b_flags |= B_AGE; 1773 /* remaining buffers */ 1774 } else if (bp->b_flags & B_DELWRI) 1775 qindex = QUEUE_DIRTY; 1776 else 1777 qindex = QUEUE_CLEAN; 1778 1779 binsfree(bp, qindex); 1780 1781 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 1782 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1783 panic("brelse: not dirty"); 1784 /* unlock */ 1785 BUF_UNLOCK(bp); 1786} 1787 1788/* 1789 * Release a buffer back to the appropriate queue but do not try to free 1790 * it. The buffer is expected to be used again soon. 1791 * 1792 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1793 * biodone() to requeue an async I/O on completion. It is also used when 1794 * known good buffers need to be requeued but we think we may need the data 1795 * again soon. 1796 * 1797 * XXX we should be able to leave the B_RELBUF hint set on completion. 1798 */ 1799void 1800bqrelse(struct buf *bp) 1801{ 1802 int qindex; 1803 1804 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1805 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1806 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1807 1808 if (BUF_LOCKRECURSED(bp)) { 1809 /* do not release to free list */ 1810 BUF_UNLOCK(bp); 1811 return; 1812 } 1813 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1814 1815 if (bp->b_flags & B_MANAGED) { 1816 if (bp->b_flags & B_REMFREE) 1817 bremfreef(bp); 1818 goto out; 1819 } 1820 1821 /* buffers with stale but valid contents */ 1822 if (bp->b_flags & B_DELWRI) { 1823 qindex = QUEUE_DIRTY; 1824 } else { 1825 if ((bp->b_flags & B_DELWRI) == 0 && 1826 (bp->b_xflags & BX_VNDIRTY)) 1827 panic("bqrelse: not dirty"); 1828 /* 1829 * BKGRDINPROG can only be set with the buf and bufobj 1830 * locks both held. We tolerate a race to clear it here. 1831 */ 1832 if (buf_vm_page_count_severe() && 1833 (bp->b_vflags & BV_BKGRDINPROG) == 0) { 1834 /* 1835 * We are too low on memory, we have to try to free 1836 * the buffer (most importantly: the wired pages 1837 * making up its backing store) *now*. 1838 */ 1839 brelse(bp); 1840 return; 1841 } 1842 qindex = QUEUE_CLEAN; 1843 } 1844 binsfree(bp, qindex); 1845 1846out: 1847 /* unlock */ 1848 BUF_UNLOCK(bp); 1849} 1850 1851/* Give pages used by the bp back to the VM system (where possible) */ 1852static void 1853vfs_vmio_release(struct buf *bp) 1854{ 1855 vm_object_t obj; 1856 vm_page_t m; 1857 int i; 1858 1859 if ((bp->b_flags & B_UNMAPPED) == 0) { 1860 BUF_CHECK_MAPPED(bp); 1861 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages); 1862 } else 1863 BUF_CHECK_UNMAPPED(bp); 1864 obj = bp->b_bufobj->bo_object; 1865 if (obj != NULL) 1866 VM_OBJECT_WLOCK(obj); 1867 for (i = 0; i < bp->b_npages; i++) { 1868 m = bp->b_pages[i]; 1869 bp->b_pages[i] = NULL; 1870 /* 1871 * In order to keep page LRU ordering consistent, put 1872 * everything on the inactive queue. 1873 */ 1874 vm_page_lock(m); 1875 vm_page_unwire(m, 0); 1876 1877 /* 1878 * Might as well free the page if we can and it has 1879 * no valid data. We also free the page if the 1880 * buffer was used for direct I/O 1881 */ 1882 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid) { 1883 if (m->wire_count == 0 && !vm_page_busied(m)) 1884 vm_page_free(m); 1885 } else if (bp->b_flags & B_DIRECT) 1886 vm_page_try_to_free(m); 1887 else if (buf_vm_page_count_severe()) 1888 vm_page_try_to_cache(m); 1889 vm_page_unlock(m); 1890 } 1891 if (obj != NULL) 1892 VM_OBJECT_WUNLOCK(obj); 1893 1894 if (bp->b_bufsize) { 1895 bufspacewakeup(); 1896 bp->b_bufsize = 0; 1897 } 1898 bp->b_npages = 0; 1899 bp->b_flags &= ~B_VMIO; 1900 if (bp->b_vp) 1901 brelvp(bp); 1902} 1903 1904/* 1905 * Check to see if a block at a particular lbn is available for a clustered 1906 * write. 1907 */ 1908static int 1909vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 1910{ 1911 struct buf *bpa; 1912 int match; 1913 1914 match = 0; 1915 1916 /* If the buf isn't in core skip it */ 1917 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 1918 return (0); 1919 1920 /* If the buf is busy we don't want to wait for it */ 1921 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1922 return (0); 1923 1924 /* Only cluster with valid clusterable delayed write buffers */ 1925 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 1926 (B_DELWRI | B_CLUSTEROK)) 1927 goto done; 1928 1929 if (bpa->b_bufsize != size) 1930 goto done; 1931 1932 /* 1933 * Check to see if it is in the expected place on disk and that the 1934 * block has been mapped. 1935 */ 1936 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 1937 match = 1; 1938done: 1939 BUF_UNLOCK(bpa); 1940 return (match); 1941} 1942 1943/* 1944 * vfs_bio_awrite: 1945 * 1946 * Implement clustered async writes for clearing out B_DELWRI buffers. 1947 * This is much better then the old way of writing only one buffer at 1948 * a time. Note that we may not be presented with the buffers in the 1949 * correct order, so we search for the cluster in both directions. 1950 */ 1951int 1952vfs_bio_awrite(struct buf *bp) 1953{ 1954 struct bufobj *bo; 1955 int i; 1956 int j; 1957 daddr_t lblkno = bp->b_lblkno; 1958 struct vnode *vp = bp->b_vp; 1959 int ncl; 1960 int nwritten; 1961 int size; 1962 int maxcl; 1963 int gbflags; 1964 1965 bo = &vp->v_bufobj; 1966 gbflags = (bp->b_flags & B_UNMAPPED) != 0 ? GB_UNMAPPED : 0; 1967 /* 1968 * right now we support clustered writing only to regular files. If 1969 * we find a clusterable block we could be in the middle of a cluster 1970 * rather then at the beginning. 1971 */ 1972 if ((vp->v_type == VREG) && 1973 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1974 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1975 1976 size = vp->v_mount->mnt_stat.f_iosize; 1977 maxcl = MAXPHYS / size; 1978 1979 BO_RLOCK(bo); 1980 for (i = 1; i < maxcl; i++) 1981 if (vfs_bio_clcheck(vp, size, lblkno + i, 1982 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 1983 break; 1984 1985 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 1986 if (vfs_bio_clcheck(vp, size, lblkno - j, 1987 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 1988 break; 1989 BO_RUNLOCK(bo); 1990 --j; 1991 ncl = i + j; 1992 /* 1993 * this is a possible cluster write 1994 */ 1995 if (ncl != 1) { 1996 BUF_UNLOCK(bp); 1997 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl, 1998 gbflags); 1999 return (nwritten); 2000 } 2001 } 2002 bremfree(bp); 2003 bp->b_flags |= B_ASYNC; 2004 /* 2005 * default (old) behavior, writing out only one block 2006 * 2007 * XXX returns b_bufsize instead of b_bcount for nwritten? 2008 */ 2009 nwritten = bp->b_bufsize; 2010 (void) bwrite(bp); 2011 2012 return (nwritten); 2013} 2014 2015static void 2016setbufkva(struct buf *bp, vm_offset_t addr, int maxsize, int gbflags) 2017{ 2018 2019 KASSERT((bp->b_flags & (B_UNMAPPED | B_KVAALLOC)) == 0 && 2020 bp->b_kvasize == 0, ("call bfreekva(%p)", bp)); 2021 if ((gbflags & GB_UNMAPPED) == 0) { 2022 bp->b_kvabase = (caddr_t)addr; 2023 } else if ((gbflags & GB_KVAALLOC) != 0) { 2024 KASSERT((gbflags & GB_UNMAPPED) != 0, 2025 ("GB_KVAALLOC without GB_UNMAPPED")); 2026 bp->b_kvaalloc = (caddr_t)addr; 2027 bp->b_flags |= B_UNMAPPED | B_KVAALLOC; 2028 atomic_add_long(&unmapped_bufspace, bp->b_kvasize); 2029 } 2030 bp->b_kvasize = maxsize; 2031} 2032 2033/* 2034 * Allocate the buffer KVA and set b_kvasize. Also set b_kvabase if 2035 * needed. 2036 */ 2037static int 2038allocbufkva(struct buf *bp, int maxsize, int gbflags) 2039{ 2040 vm_offset_t addr; 2041 2042 bfreekva(bp); 2043 addr = 0; 2044 2045 if (vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr)) { 2046 /* 2047 * Buffer map is too fragmented. Request the caller 2048 * to defragment the map. 2049 */ 2050 atomic_add_int(&bufdefragcnt, 1); 2051 return (1); 2052 } 2053 setbufkva(bp, addr, maxsize, gbflags); 2054 atomic_add_long(&bufspace, bp->b_kvasize); 2055 return (0); 2056} 2057 2058/* 2059 * Ask the bufdaemon for help, or act as bufdaemon itself, when a 2060 * locked vnode is supplied. 2061 */ 2062static void 2063getnewbuf_bufd_help(struct vnode *vp, int gbflags, int slpflag, int slptimeo, 2064 int defrag) 2065{ 2066 struct thread *td; 2067 char *waitmsg; 2068 int error, fl, flags, norunbuf; 2069 2070 mtx_assert(&bqclean, MA_OWNED); 2071 2072 if (defrag) { 2073 flags = VFS_BIO_NEED_BUFSPACE; 2074 waitmsg = "nbufkv"; 2075 } else if (bufspace >= hibufspace) { 2076 waitmsg = "nbufbs"; 2077 flags = VFS_BIO_NEED_BUFSPACE; 2078 } else { 2079 waitmsg = "newbuf"; 2080 flags = VFS_BIO_NEED_ANY; 2081 } 2082 atomic_set_int(&needsbuffer, flags); 2083 mtx_unlock(&bqclean); 2084 2085 bd_speedup(); /* heeeelp */ 2086 if ((gbflags & GB_NOWAIT_BD) != 0) 2087 return; 2088 2089 td = curthread; 2090 rw_wlock(&nblock); 2091 while ((needsbuffer & flags) != 0) { 2092 if (vp != NULL && vp->v_type != VCHR && 2093 (td->td_pflags & TDP_BUFNEED) == 0) { 2094 rw_wunlock(&nblock); 2095 /* 2096 * getblk() is called with a vnode locked, and 2097 * some majority of the dirty buffers may as 2098 * well belong to the vnode. Flushing the 2099 * buffers there would make a progress that 2100 * cannot be achieved by the buf_daemon, that 2101 * cannot lock the vnode. 2102 */ 2103 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) | 2104 (td->td_pflags & TDP_NORUNNINGBUF); 2105 2106 /* 2107 * Play bufdaemon. The getnewbuf() function 2108 * may be called while the thread owns lock 2109 * for another dirty buffer for the same 2110 * vnode, which makes it impossible to use 2111 * VOP_FSYNC() there, due to the buffer lock 2112 * recursion. 2113 */ 2114 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF; 2115 fl = buf_flush(vp, flushbufqtarget); 2116 td->td_pflags &= norunbuf; 2117 rw_wlock(&nblock); 2118 if (fl != 0) 2119 continue; 2120 if ((needsbuffer & flags) == 0) 2121 break; 2122 } 2123 error = rw_sleep(__DEVOLATILE(void *, &needsbuffer), &nblock, 2124 (PRIBIO + 4) | slpflag, waitmsg, slptimeo); 2125 if (error != 0) 2126 break; 2127 } 2128 rw_wunlock(&nblock); 2129} 2130 2131static void 2132getnewbuf_reuse_bp(struct buf *bp, int qindex) 2133{ 2134 2135 CTR6(KTR_BUF, "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d " 2136 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags, 2137 bp->b_kvasize, bp->b_bufsize, qindex); 2138 mtx_assert(&bqclean, MA_NOTOWNED); 2139 2140 /* 2141 * Note: we no longer distinguish between VMIO and non-VMIO 2142 * buffers. 2143 */ 2144 KASSERT((bp->b_flags & B_DELWRI) == 0, 2145 ("delwri buffer %p found in queue %d", bp, qindex)); 2146 2147 if (qindex == QUEUE_CLEAN) { 2148 if (bp->b_flags & B_VMIO) { 2149 bp->b_flags &= ~B_ASYNC; 2150 vfs_vmio_release(bp); 2151 } 2152 if (bp->b_vp != NULL) 2153 brelvp(bp); 2154 } 2155 2156 /* 2157 * Get the rest of the buffer freed up. b_kva* is still valid 2158 * after this operation. 2159 */ 2160 2161 if (bp->b_rcred != NOCRED) { 2162 crfree(bp->b_rcred); 2163 bp->b_rcred = NOCRED; 2164 } 2165 if (bp->b_wcred != NOCRED) { 2166 crfree(bp->b_wcred); 2167 bp->b_wcred = NOCRED; 2168 } 2169 if (!LIST_EMPTY(&bp->b_dep)) 2170 buf_deallocate(bp); 2171 if (bp->b_vflags & BV_BKGRDINPROG) 2172 panic("losing buffer 3"); 2173 KASSERT(bp->b_vp == NULL, ("bp: %p still has vnode %p. qindex: %d", 2174 bp, bp->b_vp, qindex)); 2175 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 2176 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags)); 2177 2178 if (bp->b_bufsize) 2179 allocbuf(bp, 0); 2180 2181 bp->b_flags &= B_UNMAPPED | B_KVAALLOC; 2182 bp->b_ioflags = 0; 2183 bp->b_xflags = 0; 2184 KASSERT((bp->b_flags & B_INFREECNT) == 0, 2185 ("buf %p still counted as free?", bp)); 2186 bp->b_vflags = 0; 2187 bp->b_vp = NULL; 2188 bp->b_blkno = bp->b_lblkno = 0; 2189 bp->b_offset = NOOFFSET; 2190 bp->b_iodone = 0; 2191 bp->b_error = 0; 2192 bp->b_resid = 0; 2193 bp->b_bcount = 0; 2194 bp->b_npages = 0; 2195 bp->b_dirtyoff = bp->b_dirtyend = 0; 2196 bp->b_bufobj = NULL; 2197 bp->b_pin_count = 0; 2198 bp->b_fsprivate1 = NULL; 2199 bp->b_fsprivate2 = NULL; 2200 bp->b_fsprivate3 = NULL; 2201 2202 LIST_INIT(&bp->b_dep); 2203} 2204 2205static int flushingbufs; 2206 2207static struct buf * 2208getnewbuf_scan(int maxsize, int defrag, int unmapped, int metadata) 2209{ 2210 struct buf *bp, *nbp; 2211 int nqindex, qindex, pass; 2212 2213 KASSERT(!unmapped || !defrag, ("both unmapped and defrag")); 2214 2215 pass = 1; 2216restart: 2217 atomic_add_int(&getnewbufrestarts, 1); 2218 2219 /* 2220 * Setup for scan. If we do not have enough free buffers, 2221 * we setup a degenerate case that immediately fails. Note 2222 * that if we are specially marked process, we are allowed to 2223 * dip into our reserves. 2224 * 2225 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 2226 * for the allocation of the mapped buffer. For unmapped, the 2227 * easiest is to start with EMPTY outright. 2228 * 2229 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 2230 * However, there are a number of cases (defragging, reusing, ...) 2231 * where we cannot backup. 2232 */ 2233 nbp = NULL; 2234 mtx_lock(&bqclean); 2235 if (!defrag && unmapped) { 2236 nqindex = QUEUE_EMPTY; 2237 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 2238 } 2239 if (nbp == NULL) { 2240 nqindex = QUEUE_EMPTYKVA; 2241 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 2242 } 2243 2244 /* 2245 * If no EMPTYKVA buffers and we are either defragging or 2246 * reusing, locate a CLEAN buffer to free or reuse. If 2247 * bufspace useage is low skip this step so we can allocate a 2248 * new buffer. 2249 */ 2250 if (nbp == NULL && (defrag || bufspace >= lobufspace)) { 2251 nqindex = QUEUE_CLEAN; 2252 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2253 } 2254 2255 /* 2256 * If we could not find or were not allowed to reuse a CLEAN 2257 * buffer, check to see if it is ok to use an EMPTY buffer. 2258 * We can only use an EMPTY buffer if allocating its KVA would 2259 * not otherwise run us out of buffer space. No KVA is needed 2260 * for the unmapped allocation. 2261 */ 2262 if (nbp == NULL && defrag == 0 && (bufspace + maxsize < hibufspace || 2263 metadata)) { 2264 nqindex = QUEUE_EMPTY; 2265 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 2266 } 2267 2268 /* 2269 * All available buffers might be clean, retry ignoring the 2270 * lobufspace as the last resort. 2271 */ 2272 if (nbp == NULL && !TAILQ_EMPTY(&bufqueues[QUEUE_CLEAN])) { 2273 nqindex = QUEUE_CLEAN; 2274 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2275 } 2276 2277 /* 2278 * Run scan, possibly freeing data and/or kva mappings on the fly 2279 * depending. 2280 */ 2281 while ((bp = nbp) != NULL) { 2282 qindex = nqindex; 2283 2284 /* 2285 * Calculate next bp (we can only use it if we do not 2286 * block or do other fancy things). 2287 */ 2288 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 2289 switch (qindex) { 2290 case QUEUE_EMPTY: 2291 nqindex = QUEUE_EMPTYKVA; 2292 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 2293 if (nbp != NULL) 2294 break; 2295 /* FALLTHROUGH */ 2296 case QUEUE_EMPTYKVA: 2297 nqindex = QUEUE_CLEAN; 2298 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2299 if (nbp != NULL) 2300 break; 2301 /* FALLTHROUGH */ 2302 case QUEUE_CLEAN: 2303 if (metadata && pass == 1) { 2304 pass = 2; 2305 nqindex = QUEUE_EMPTY; 2306 nbp = TAILQ_FIRST( 2307 &bufqueues[QUEUE_EMPTY]); 2308 } 2309 /* 2310 * nbp is NULL. 2311 */ 2312 break; 2313 } 2314 } 2315 /* 2316 * If we are defragging then we need a buffer with 2317 * b_kvasize != 0. XXX this situation should no longer 2318 * occur, if defrag is non-zero the buffer's b_kvasize 2319 * should also be non-zero at this point. XXX 2320 */ 2321 if (defrag && bp->b_kvasize == 0) { 2322 printf("Warning: defrag empty buffer %p\n", bp); 2323 continue; 2324 } 2325 2326 /* 2327 * Start freeing the bp. This is somewhat involved. nbp 2328 * remains valid only for QUEUE_EMPTY[KVA] bp's. 2329 */ 2330 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2331 continue; 2332 /* 2333 * BKGRDINPROG can only be set with the buf and bufobj 2334 * locks both held. We tolerate a race to clear it here. 2335 */ 2336 if (bp->b_vflags & BV_BKGRDINPROG) { 2337 BUF_UNLOCK(bp); 2338 continue; 2339 } 2340 2341 KASSERT(bp->b_qindex == qindex, 2342 ("getnewbuf: inconsistent queue %d bp %p", qindex, bp)); 2343 2344 bremfreel(bp); 2345 mtx_unlock(&bqclean); 2346 /* 2347 * NOTE: nbp is now entirely invalid. We can only restart 2348 * the scan from this point on. 2349 */ 2350 2351 getnewbuf_reuse_bp(bp, qindex); 2352 mtx_assert(&bqclean, MA_NOTOWNED); 2353 2354 /* 2355 * If we are defragging then free the buffer. 2356 */ 2357 if (defrag) { 2358 bp->b_flags |= B_INVAL; 2359 bfreekva(bp); 2360 brelse(bp); 2361 defrag = 0; 2362 goto restart; 2363 } 2364 2365 /* 2366 * Notify any waiters for the buffer lock about 2367 * identity change by freeing the buffer. 2368 */ 2369 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp)) { 2370 bp->b_flags |= B_INVAL; 2371 bfreekva(bp); 2372 brelse(bp); 2373 goto restart; 2374 } 2375 2376 if (metadata) 2377 break; 2378 2379 /* 2380 * If we are overcomitted then recover the buffer and its 2381 * KVM space. This occurs in rare situations when multiple 2382 * processes are blocked in getnewbuf() or allocbuf(). 2383 */ 2384 if (bufspace >= hibufspace) 2385 flushingbufs = 1; 2386 if (flushingbufs && bp->b_kvasize != 0) { 2387 bp->b_flags |= B_INVAL; 2388 bfreekva(bp); 2389 brelse(bp); 2390 goto restart; 2391 } 2392 if (bufspace < lobufspace) 2393 flushingbufs = 0; 2394 break; 2395 } 2396 return (bp); 2397} 2398 2399/* 2400 * getnewbuf: 2401 * 2402 * Find and initialize a new buffer header, freeing up existing buffers 2403 * in the bufqueues as necessary. The new buffer is returned locked. 2404 * 2405 * Important: B_INVAL is not set. If the caller wishes to throw the 2406 * buffer away, the caller must set B_INVAL prior to calling brelse(). 2407 * 2408 * We block if: 2409 * We have insufficient buffer headers 2410 * We have insufficient buffer space 2411 * buffer_arena is too fragmented ( space reservation fails ) 2412 * If we have to flush dirty buffers ( but we try to avoid this ) 2413 */ 2414static struct buf * 2415getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int size, int maxsize, 2416 int gbflags) 2417{ 2418 struct buf *bp; 2419 int defrag, metadata; 2420 2421 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 2422 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 2423 if (!unmapped_buf_allowed) 2424 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC); 2425 2426 defrag = 0; 2427 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 || 2428 vp->v_type == VCHR) 2429 metadata = 1; 2430 else 2431 metadata = 0; 2432 /* 2433 * We can't afford to block since we might be holding a vnode lock, 2434 * which may prevent system daemons from running. We deal with 2435 * low-memory situations by proactively returning memory and running 2436 * async I/O rather then sync I/O. 2437 */ 2438 atomic_add_int(&getnewbufcalls, 1); 2439 atomic_subtract_int(&getnewbufrestarts, 1); 2440restart: 2441 bp = getnewbuf_scan(maxsize, defrag, (gbflags & (GB_UNMAPPED | 2442 GB_KVAALLOC)) == GB_UNMAPPED, metadata); 2443 if (bp != NULL) 2444 defrag = 0; 2445 2446 /* 2447 * If we exhausted our list, sleep as appropriate. We may have to 2448 * wakeup various daemons and write out some dirty buffers. 2449 * 2450 * Generally we are sleeping due to insufficient buffer space. 2451 */ 2452 if (bp == NULL) { 2453 mtx_assert(&bqclean, MA_OWNED); 2454 getnewbuf_bufd_help(vp, gbflags, slpflag, slptimeo, defrag); 2455 mtx_assert(&bqclean, MA_NOTOWNED); 2456 } else if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == GB_UNMAPPED) { 2457 mtx_assert(&bqclean, MA_NOTOWNED); 2458 2459 bfreekva(bp); 2460 bp->b_flags |= B_UNMAPPED; 2461 bp->b_kvabase = bp->b_data = unmapped_buf; 2462 bp->b_kvasize = maxsize; 2463 atomic_add_long(&bufspace, bp->b_kvasize); 2464 atomic_add_long(&unmapped_bufspace, bp->b_kvasize); 2465 atomic_add_int(&bufreusecnt, 1); 2466 } else { 2467 mtx_assert(&bqclean, MA_NOTOWNED); 2468 2469 /* 2470 * We finally have a valid bp. We aren't quite out of the 2471 * woods, we still have to reserve kva space. In order 2472 * to keep fragmentation sane we only allocate kva in 2473 * BKVASIZE chunks. 2474 */ 2475 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2476 2477 if (maxsize != bp->b_kvasize || (bp->b_flags & (B_UNMAPPED | 2478 B_KVAALLOC)) == B_UNMAPPED) { 2479 if (allocbufkva(bp, maxsize, gbflags)) { 2480 defrag = 1; 2481 bp->b_flags |= B_INVAL; 2482 brelse(bp); 2483 goto restart; 2484 } 2485 atomic_add_int(&bufreusecnt, 1); 2486 } else if ((bp->b_flags & B_KVAALLOC) != 0 && 2487 (gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == 0) { 2488 /* 2489 * If the reused buffer has KVA allocated, 2490 * reassign b_kvaalloc to b_kvabase. 2491 */ 2492 bp->b_kvabase = bp->b_kvaalloc; 2493 bp->b_flags &= ~B_KVAALLOC; 2494 atomic_subtract_long(&unmapped_bufspace, 2495 bp->b_kvasize); 2496 atomic_add_int(&bufreusecnt, 1); 2497 } else if ((bp->b_flags & (B_UNMAPPED | B_KVAALLOC)) == 0 && 2498 (gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == (GB_UNMAPPED | 2499 GB_KVAALLOC)) { 2500 /* 2501 * The case of reused buffer already have KVA 2502 * mapped, but the request is for unmapped 2503 * buffer with KVA allocated. 2504 */ 2505 bp->b_kvaalloc = bp->b_kvabase; 2506 bp->b_data = bp->b_kvabase = unmapped_buf; 2507 bp->b_flags |= B_UNMAPPED | B_KVAALLOC; 2508 atomic_add_long(&unmapped_bufspace, 2509 bp->b_kvasize); 2510 atomic_add_int(&bufreusecnt, 1); 2511 } 2512 if ((gbflags & GB_UNMAPPED) == 0) { 2513 bp->b_saveaddr = bp->b_kvabase; 2514 bp->b_data = bp->b_saveaddr; 2515 bp->b_flags &= ~B_UNMAPPED; 2516 BUF_CHECK_MAPPED(bp); 2517 } 2518 } 2519 return (bp); 2520} 2521 2522/* 2523 * buf_daemon: 2524 * 2525 * buffer flushing daemon. Buffers are normally flushed by the 2526 * update daemon but if it cannot keep up this process starts to 2527 * take the load in an attempt to prevent getnewbuf() from blocking. 2528 */ 2529 2530static struct kproc_desc buf_kp = { 2531 "bufdaemon", 2532 buf_daemon, 2533 &bufdaemonproc 2534}; 2535SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 2536 2537static int 2538buf_flush(struct vnode *vp, int target) 2539{ 2540 int flushed; 2541 2542 flushed = flushbufqueues(vp, target, 0); 2543 if (flushed == 0) { 2544 /* 2545 * Could not find any buffers without rollback 2546 * dependencies, so just write the first one 2547 * in the hopes of eventually making progress. 2548 */ 2549 if (vp != NULL && target > 2) 2550 target /= 2; 2551 flushbufqueues(vp, target, 1); 2552 } 2553 return (flushed); 2554} 2555 2556static void 2557buf_daemon() 2558{ 2559 int lodirty; 2560 2561 /* 2562 * This process needs to be suspended prior to shutdown sync. 2563 */ 2564 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2565 SHUTDOWN_PRI_LAST); 2566 2567 /* 2568 * This process is allowed to take the buffer cache to the limit 2569 */ 2570 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 2571 mtx_lock(&bdlock); 2572 for (;;) { 2573 bd_request = 0; 2574 mtx_unlock(&bdlock); 2575 2576 kproc_suspend_check(bufdaemonproc); 2577 lodirty = lodirtybuffers; 2578 if (bd_speedupreq) { 2579 lodirty = numdirtybuffers / 2; 2580 bd_speedupreq = 0; 2581 } 2582 /* 2583 * Do the flush. Limit the amount of in-transit I/O we 2584 * allow to build up, otherwise we would completely saturate 2585 * the I/O system. 2586 */ 2587 while (numdirtybuffers > lodirty) { 2588 if (buf_flush(NULL, numdirtybuffers - lodirty) == 0) 2589 break; 2590 kern_yield(PRI_USER); 2591 } 2592 2593 /* 2594 * Only clear bd_request if we have reached our low water 2595 * mark. The buf_daemon normally waits 1 second and 2596 * then incrementally flushes any dirty buffers that have 2597 * built up, within reason. 2598 * 2599 * If we were unable to hit our low water mark and couldn't 2600 * find any flushable buffers, we sleep for a short period 2601 * to avoid endless loops on unlockable buffers. 2602 */ 2603 mtx_lock(&bdlock); 2604 if (numdirtybuffers <= lodirtybuffers) { 2605 /* 2606 * We reached our low water mark, reset the 2607 * request and sleep until we are needed again. 2608 * The sleep is just so the suspend code works. 2609 */ 2610 bd_request = 0; 2611 /* 2612 * Do an extra wakeup in case dirty threshold 2613 * changed via sysctl and the explicit transition 2614 * out of shortfall was missed. 2615 */ 2616 bdirtywakeup(); 2617 if (runningbufspace <= lorunningspace) 2618 runningwakeup(); 2619 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 2620 } else { 2621 /* 2622 * We couldn't find any flushable dirty buffers but 2623 * still have too many dirty buffers, we 2624 * have to sleep and try again. (rare) 2625 */ 2626 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 2627 } 2628 } 2629} 2630 2631/* 2632 * flushbufqueues: 2633 * 2634 * Try to flush a buffer in the dirty queue. We must be careful to 2635 * free up B_INVAL buffers instead of write them, which NFS is 2636 * particularly sensitive to. 2637 */ 2638static int flushwithdeps = 0; 2639SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 2640 0, "Number of buffers flushed with dependecies that require rollbacks"); 2641 2642static int 2643flushbufqueues(struct vnode *lvp, int target, int flushdeps) 2644{ 2645 struct buf *sentinel; 2646 struct vnode *vp; 2647 struct mount *mp; 2648 struct buf *bp; 2649 int hasdeps; 2650 int flushed; 2651 int queue; 2652 int error; 2653 bool unlock; 2654 2655 flushed = 0; 2656 queue = QUEUE_DIRTY; 2657 bp = NULL; 2658 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 2659 sentinel->b_qindex = QUEUE_SENTINEL; 2660 mtx_lock(&bqdirty); 2661 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist); 2662 mtx_unlock(&bqdirty); 2663 while (flushed != target) { 2664 maybe_yield(); 2665 mtx_lock(&bqdirty); 2666 bp = TAILQ_NEXT(sentinel, b_freelist); 2667 if (bp != NULL) { 2668 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2669 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel, 2670 b_freelist); 2671 } else { 2672 mtx_unlock(&bqdirty); 2673 break; 2674 } 2675 /* 2676 * Skip sentinels inserted by other invocations of the 2677 * flushbufqueues(), taking care to not reorder them. 2678 * 2679 * Only flush the buffers that belong to the 2680 * vnode locked by the curthread. 2681 */ 2682 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL && 2683 bp->b_vp != lvp)) { 2684 mtx_unlock(&bqdirty); 2685 continue; 2686 } 2687 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL); 2688 mtx_unlock(&bqdirty); 2689 if (error != 0) 2690 continue; 2691 if (bp->b_pin_count > 0) { 2692 BUF_UNLOCK(bp); 2693 continue; 2694 } 2695 /* 2696 * BKGRDINPROG can only be set with the buf and bufobj 2697 * locks both held. We tolerate a race to clear it here. 2698 */ 2699 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 2700 (bp->b_flags & B_DELWRI) == 0) { 2701 BUF_UNLOCK(bp); 2702 continue; 2703 } 2704 if (bp->b_flags & B_INVAL) { 2705 bremfreef(bp); 2706 brelse(bp); 2707 flushed++; 2708 continue; 2709 } 2710 2711 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 2712 if (flushdeps == 0) { 2713 BUF_UNLOCK(bp); 2714 continue; 2715 } 2716 hasdeps = 1; 2717 } else 2718 hasdeps = 0; 2719 /* 2720 * We must hold the lock on a vnode before writing 2721 * one of its buffers. Otherwise we may confuse, or 2722 * in the case of a snapshot vnode, deadlock the 2723 * system. 2724 * 2725 * The lock order here is the reverse of the normal 2726 * of vnode followed by buf lock. This is ok because 2727 * the NOWAIT will prevent deadlock. 2728 */ 2729 vp = bp->b_vp; 2730 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 2731 BUF_UNLOCK(bp); 2732 continue; 2733 } 2734 if (lvp == NULL) { 2735 unlock = true; 2736 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT); 2737 } else { 2738 ASSERT_VOP_LOCKED(vp, "getbuf"); 2739 unlock = false; 2740 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 : 2741 vn_lock(vp, LK_TRYUPGRADE); 2742 } 2743 if (error == 0) { 2744 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 2745 bp, bp->b_vp, bp->b_flags); 2746 if (curproc == bufdaemonproc) { 2747 vfs_bio_awrite(bp); 2748 } else { 2749 bremfree(bp); 2750 bwrite(bp); 2751 notbufdflushes++; 2752 } 2753 vn_finished_write(mp); 2754 if (unlock) 2755 VOP_UNLOCK(vp, 0); 2756 flushwithdeps += hasdeps; 2757 flushed++; 2758 2759 /* 2760 * Sleeping on runningbufspace while holding 2761 * vnode lock leads to deadlock. 2762 */ 2763 if (curproc == bufdaemonproc && 2764 runningbufspace > hirunningspace) 2765 waitrunningbufspace(); 2766 continue; 2767 } 2768 vn_finished_write(mp); 2769 BUF_UNLOCK(bp); 2770 } 2771 mtx_lock(&bqdirty); 2772 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2773 mtx_unlock(&bqdirty); 2774 free(sentinel, M_TEMP); 2775 return (flushed); 2776} 2777 2778/* 2779 * Check to see if a block is currently memory resident. 2780 */ 2781struct buf * 2782incore(struct bufobj *bo, daddr_t blkno) 2783{ 2784 struct buf *bp; 2785 2786 BO_RLOCK(bo); 2787 bp = gbincore(bo, blkno); 2788 BO_RUNLOCK(bo); 2789 return (bp); 2790} 2791 2792/* 2793 * Returns true if no I/O is needed to access the 2794 * associated VM object. This is like incore except 2795 * it also hunts around in the VM system for the data. 2796 */ 2797 2798static int 2799inmem(struct vnode * vp, daddr_t blkno) 2800{ 2801 vm_object_t obj; 2802 vm_offset_t toff, tinc, size; 2803 vm_page_t m; 2804 vm_ooffset_t off; 2805 2806 ASSERT_VOP_LOCKED(vp, "inmem"); 2807 2808 if (incore(&vp->v_bufobj, blkno)) 2809 return 1; 2810 if (vp->v_mount == NULL) 2811 return 0; 2812 obj = vp->v_object; 2813 if (obj == NULL) 2814 return (0); 2815 2816 size = PAGE_SIZE; 2817 if (size > vp->v_mount->mnt_stat.f_iosize) 2818 size = vp->v_mount->mnt_stat.f_iosize; 2819 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2820 2821 VM_OBJECT_RLOCK(obj); 2822 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2823 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2824 if (!m) 2825 goto notinmem; 2826 tinc = size; 2827 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2828 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2829 if (vm_page_is_valid(m, 2830 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2831 goto notinmem; 2832 } 2833 VM_OBJECT_RUNLOCK(obj); 2834 return 1; 2835 2836notinmem: 2837 VM_OBJECT_RUNLOCK(obj); 2838 return (0); 2839} 2840 2841/* 2842 * Set the dirty range for a buffer based on the status of the dirty 2843 * bits in the pages comprising the buffer. The range is limited 2844 * to the size of the buffer. 2845 * 2846 * Tell the VM system that the pages associated with this buffer 2847 * are clean. This is used for delayed writes where the data is 2848 * going to go to disk eventually without additional VM intevention. 2849 * 2850 * Note that while we only really need to clean through to b_bcount, we 2851 * just go ahead and clean through to b_bufsize. 2852 */ 2853static void 2854vfs_clean_pages_dirty_buf(struct buf *bp) 2855{ 2856 vm_ooffset_t foff, noff, eoff; 2857 vm_page_t m; 2858 int i; 2859 2860 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 2861 return; 2862 2863 foff = bp->b_offset; 2864 KASSERT(bp->b_offset != NOOFFSET, 2865 ("vfs_clean_pages_dirty_buf: no buffer offset")); 2866 2867 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 2868 vfs_drain_busy_pages(bp); 2869 vfs_setdirty_locked_object(bp); 2870 for (i = 0; i < bp->b_npages; i++) { 2871 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2872 eoff = noff; 2873 if (eoff > bp->b_offset + bp->b_bufsize) 2874 eoff = bp->b_offset + bp->b_bufsize; 2875 m = bp->b_pages[i]; 2876 vfs_page_set_validclean(bp, foff, m); 2877 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 2878 foff = noff; 2879 } 2880 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 2881} 2882 2883static void 2884vfs_setdirty_locked_object(struct buf *bp) 2885{ 2886 vm_object_t object; 2887 int i; 2888 2889 object = bp->b_bufobj->bo_object; 2890 VM_OBJECT_ASSERT_WLOCKED(object); 2891 2892 /* 2893 * We qualify the scan for modified pages on whether the 2894 * object has been flushed yet. 2895 */ 2896 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) { 2897 vm_offset_t boffset; 2898 vm_offset_t eoffset; 2899 2900 /* 2901 * test the pages to see if they have been modified directly 2902 * by users through the VM system. 2903 */ 2904 for (i = 0; i < bp->b_npages; i++) 2905 vm_page_test_dirty(bp->b_pages[i]); 2906 2907 /* 2908 * Calculate the encompassing dirty range, boffset and eoffset, 2909 * (eoffset - boffset) bytes. 2910 */ 2911 2912 for (i = 0; i < bp->b_npages; i++) { 2913 if (bp->b_pages[i]->dirty) 2914 break; 2915 } 2916 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2917 2918 for (i = bp->b_npages - 1; i >= 0; --i) { 2919 if (bp->b_pages[i]->dirty) { 2920 break; 2921 } 2922 } 2923 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2924 2925 /* 2926 * Fit it to the buffer. 2927 */ 2928 2929 if (eoffset > bp->b_bcount) 2930 eoffset = bp->b_bcount; 2931 2932 /* 2933 * If we have a good dirty range, merge with the existing 2934 * dirty range. 2935 */ 2936 2937 if (boffset < eoffset) { 2938 if (bp->b_dirtyoff > boffset) 2939 bp->b_dirtyoff = boffset; 2940 if (bp->b_dirtyend < eoffset) 2941 bp->b_dirtyend = eoffset; 2942 } 2943 } 2944} 2945 2946/* 2947 * Allocate the KVA mapping for an existing buffer. It handles the 2948 * cases of both B_UNMAPPED buffer, and buffer with the preallocated 2949 * KVA which is not mapped (B_KVAALLOC). 2950 */ 2951static void 2952bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags) 2953{ 2954 struct buf *scratch_bp; 2955 int bsize, maxsize, need_mapping, need_kva; 2956 off_t offset; 2957 2958 need_mapping = (bp->b_flags & B_UNMAPPED) != 0 && 2959 (gbflags & GB_UNMAPPED) == 0; 2960 need_kva = (bp->b_flags & (B_KVAALLOC | B_UNMAPPED)) == B_UNMAPPED && 2961 (gbflags & GB_KVAALLOC) != 0; 2962 if (!need_mapping && !need_kva) 2963 return; 2964 2965 BUF_CHECK_UNMAPPED(bp); 2966 2967 if (need_mapping && (bp->b_flags & B_KVAALLOC) != 0) { 2968 /* 2969 * Buffer is not mapped, but the KVA was already 2970 * reserved at the time of the instantiation. Use the 2971 * allocated space. 2972 */ 2973 bp->b_flags &= ~B_KVAALLOC; 2974 KASSERT(bp->b_kvaalloc != 0, ("kvaalloc == 0")); 2975 bp->b_kvabase = bp->b_kvaalloc; 2976 atomic_subtract_long(&unmapped_bufspace, bp->b_kvasize); 2977 goto has_addr; 2978 } 2979 2980 /* 2981 * Calculate the amount of the address space we would reserve 2982 * if the buffer was mapped. 2983 */ 2984 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize; 2985 offset = blkno * bsize; 2986 maxsize = size + (offset & PAGE_MASK); 2987 maxsize = imax(maxsize, bsize); 2988 2989mapping_loop: 2990 if (allocbufkva(bp, maxsize, gbflags)) { 2991 /* 2992 * Request defragmentation. getnewbuf() returns us the 2993 * allocated space by the scratch buffer KVA. 2994 */ 2995 scratch_bp = getnewbuf(bp->b_vp, 0, 0, size, maxsize, gbflags | 2996 (GB_UNMAPPED | GB_KVAALLOC)); 2997 if (scratch_bp == NULL) { 2998 if ((gbflags & GB_NOWAIT_BD) != 0) { 2999 /* 3000 * XXXKIB: defragmentation cannot 3001 * succeed, not sure what else to do. 3002 */ 3003 panic("GB_NOWAIT_BD and B_UNMAPPED %p", bp); 3004 } 3005 atomic_add_int(&mappingrestarts, 1); 3006 goto mapping_loop; 3007 } 3008 KASSERT((scratch_bp->b_flags & B_KVAALLOC) != 0, 3009 ("scratch bp !B_KVAALLOC %p", scratch_bp)); 3010 setbufkva(bp, (vm_offset_t)scratch_bp->b_kvaalloc, 3011 scratch_bp->b_kvasize, gbflags); 3012 3013 /* Get rid of the scratch buffer. */ 3014 scratch_bp->b_kvasize = 0; 3015 scratch_bp->b_flags |= B_INVAL; 3016 scratch_bp->b_flags &= ~(B_UNMAPPED | B_KVAALLOC); 3017 brelse(scratch_bp); 3018 } 3019 if (!need_mapping) 3020 return; 3021 3022has_addr: 3023 bp->b_saveaddr = bp->b_kvabase; 3024 bp->b_data = bp->b_saveaddr; /* b_offset is handled by bpmap_qenter */ 3025 bp->b_flags &= ~B_UNMAPPED; 3026 BUF_CHECK_MAPPED(bp); 3027 bpmap_qenter(bp); 3028} 3029 3030/* 3031 * getblk: 3032 * 3033 * Get a block given a specified block and offset into a file/device. 3034 * The buffers B_DONE bit will be cleared on return, making it almost 3035 * ready for an I/O initiation. B_INVAL may or may not be set on 3036 * return. The caller should clear B_INVAL prior to initiating a 3037 * READ. 3038 * 3039 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 3040 * an existing buffer. 3041 * 3042 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 3043 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 3044 * and then cleared based on the backing VM. If the previous buffer is 3045 * non-0-sized but invalid, B_CACHE will be cleared. 3046 * 3047 * If getblk() must create a new buffer, the new buffer is returned with 3048 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 3049 * case it is returned with B_INVAL clear and B_CACHE set based on the 3050 * backing VM. 3051 * 3052 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 3053 * B_CACHE bit is clear. 3054 * 3055 * What this means, basically, is that the caller should use B_CACHE to 3056 * determine whether the buffer is fully valid or not and should clear 3057 * B_INVAL prior to issuing a read. If the caller intends to validate 3058 * the buffer by loading its data area with something, the caller needs 3059 * to clear B_INVAL. If the caller does this without issuing an I/O, 3060 * the caller should set B_CACHE ( as an optimization ), else the caller 3061 * should issue the I/O and biodone() will set B_CACHE if the I/O was 3062 * a write attempt or if it was a successfull read. If the caller 3063 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 3064 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 3065 */ 3066struct buf * 3067getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3068 int flags) 3069{ 3070 struct buf *bp; 3071 struct bufobj *bo; 3072 int bsize, error, maxsize, vmio; 3073 off_t offset; 3074 3075 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 3076 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3077 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3078 ASSERT_VOP_LOCKED(vp, "getblk"); 3079 if (size > MAXBSIZE) 3080 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 3081 if (!unmapped_buf_allowed) 3082 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3083 3084 bo = &vp->v_bufobj; 3085loop: 3086 BO_RLOCK(bo); 3087 bp = gbincore(bo, blkno); 3088 if (bp != NULL) { 3089 int lockflags; 3090 /* 3091 * Buffer is in-core. If the buffer is not busy nor managed, 3092 * it must be on a queue. 3093 */ 3094 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 3095 3096 if (flags & GB_LOCK_NOWAIT) 3097 lockflags |= LK_NOWAIT; 3098 3099 error = BUF_TIMELOCK(bp, lockflags, 3100 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo); 3101 3102 /* 3103 * If we slept and got the lock we have to restart in case 3104 * the buffer changed identities. 3105 */ 3106 if (error == ENOLCK) 3107 goto loop; 3108 /* We timed out or were interrupted. */ 3109 else if (error) 3110 return (NULL); 3111 /* If recursed, assume caller knows the rules. */ 3112 else if (BUF_LOCKRECURSED(bp)) 3113 goto end; 3114 3115 /* 3116 * The buffer is locked. B_CACHE is cleared if the buffer is 3117 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 3118 * and for a VMIO buffer B_CACHE is adjusted according to the 3119 * backing VM cache. 3120 */ 3121 if (bp->b_flags & B_INVAL) 3122 bp->b_flags &= ~B_CACHE; 3123 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 3124 bp->b_flags |= B_CACHE; 3125 if (bp->b_flags & B_MANAGED) 3126 MPASS(bp->b_qindex == QUEUE_NONE); 3127 else 3128 bremfree(bp); 3129 3130 /* 3131 * check for size inconsistencies for non-VMIO case. 3132 */ 3133 if (bp->b_bcount != size) { 3134 if ((bp->b_flags & B_VMIO) == 0 || 3135 (size > bp->b_kvasize)) { 3136 if (bp->b_flags & B_DELWRI) { 3137 /* 3138 * If buffer is pinned and caller does 3139 * not want sleep waiting for it to be 3140 * unpinned, bail out 3141 * */ 3142 if (bp->b_pin_count > 0) { 3143 if (flags & GB_LOCK_NOWAIT) { 3144 bqrelse(bp); 3145 return (NULL); 3146 } else { 3147 bunpin_wait(bp); 3148 } 3149 } 3150 bp->b_flags |= B_NOCACHE; 3151 bwrite(bp); 3152 } else { 3153 if (LIST_EMPTY(&bp->b_dep)) { 3154 bp->b_flags |= B_RELBUF; 3155 brelse(bp); 3156 } else { 3157 bp->b_flags |= B_NOCACHE; 3158 bwrite(bp); 3159 } 3160 } 3161 goto loop; 3162 } 3163 } 3164 3165 /* 3166 * Handle the case of unmapped buffer which should 3167 * become mapped, or the buffer for which KVA 3168 * reservation is requested. 3169 */ 3170 bp_unmapped_get_kva(bp, blkno, size, flags); 3171 3172 /* 3173 * If the size is inconsistant in the VMIO case, we can resize 3174 * the buffer. This might lead to B_CACHE getting set or 3175 * cleared. If the size has not changed, B_CACHE remains 3176 * unchanged from its previous state. 3177 */ 3178 if (bp->b_bcount != size) 3179 allocbuf(bp, size); 3180 3181 KASSERT(bp->b_offset != NOOFFSET, 3182 ("getblk: no buffer offset")); 3183 3184 /* 3185 * A buffer with B_DELWRI set and B_CACHE clear must 3186 * be committed before we can return the buffer in 3187 * order to prevent the caller from issuing a read 3188 * ( due to B_CACHE not being set ) and overwriting 3189 * it. 3190 * 3191 * Most callers, including NFS and FFS, need this to 3192 * operate properly either because they assume they 3193 * can issue a read if B_CACHE is not set, or because 3194 * ( for example ) an uncached B_DELWRI might loop due 3195 * to softupdates re-dirtying the buffer. In the latter 3196 * case, B_CACHE is set after the first write completes, 3197 * preventing further loops. 3198 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 3199 * above while extending the buffer, we cannot allow the 3200 * buffer to remain with B_CACHE set after the write 3201 * completes or it will represent a corrupt state. To 3202 * deal with this we set B_NOCACHE to scrap the buffer 3203 * after the write. 3204 * 3205 * We might be able to do something fancy, like setting 3206 * B_CACHE in bwrite() except if B_DELWRI is already set, 3207 * so the below call doesn't set B_CACHE, but that gets real 3208 * confusing. This is much easier. 3209 */ 3210 3211 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 3212 bp->b_flags |= B_NOCACHE; 3213 bwrite(bp); 3214 goto loop; 3215 } 3216 bp->b_flags &= ~B_DONE; 3217 } else { 3218 /* 3219 * Buffer is not in-core, create new buffer. The buffer 3220 * returned by getnewbuf() is locked. Note that the returned 3221 * buffer is also considered valid (not marked B_INVAL). 3222 */ 3223 BO_RUNLOCK(bo); 3224 /* 3225 * If the user does not want us to create the buffer, bail out 3226 * here. 3227 */ 3228 if (flags & GB_NOCREAT) 3229 return NULL; 3230 if (numfreebuffers == 0 && TD_IS_IDLETHREAD(curthread)) 3231 return NULL; 3232 3233 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize; 3234 offset = blkno * bsize; 3235 vmio = vp->v_object != NULL; 3236 if (vmio) { 3237 maxsize = size + (offset & PAGE_MASK); 3238 } else { 3239 maxsize = size; 3240 /* Do not allow non-VMIO notmapped buffers. */ 3241 flags &= ~GB_UNMAPPED; 3242 } 3243 maxsize = imax(maxsize, bsize); 3244 3245 bp = getnewbuf(vp, slpflag, slptimeo, size, maxsize, flags); 3246 if (bp == NULL) { 3247 if (slpflag || slptimeo) 3248 return NULL; 3249 goto loop; 3250 } 3251 3252 /* 3253 * This code is used to make sure that a buffer is not 3254 * created while the getnewbuf routine is blocked. 3255 * This can be a problem whether the vnode is locked or not. 3256 * If the buffer is created out from under us, we have to 3257 * throw away the one we just created. 3258 * 3259 * Note: this must occur before we associate the buffer 3260 * with the vp especially considering limitations in 3261 * the splay tree implementation when dealing with duplicate 3262 * lblkno's. 3263 */ 3264 BO_LOCK(bo); 3265 if (gbincore(bo, blkno)) { 3266 BO_UNLOCK(bo); 3267 bp->b_flags |= B_INVAL; 3268 brelse(bp); 3269 goto loop; 3270 } 3271 3272 /* 3273 * Insert the buffer into the hash, so that it can 3274 * be found by incore. 3275 */ 3276 bp->b_blkno = bp->b_lblkno = blkno; 3277 bp->b_offset = offset; 3278 bgetvp(vp, bp); 3279 BO_UNLOCK(bo); 3280 3281 /* 3282 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 3283 * buffer size starts out as 0, B_CACHE will be set by 3284 * allocbuf() for the VMIO case prior to it testing the 3285 * backing store for validity. 3286 */ 3287 3288 if (vmio) { 3289 bp->b_flags |= B_VMIO; 3290 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 3291 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 3292 bp, vp->v_object, bp->b_bufobj->bo_object)); 3293 } else { 3294 bp->b_flags &= ~B_VMIO; 3295 KASSERT(bp->b_bufobj->bo_object == NULL, 3296 ("ARGH! has b_bufobj->bo_object %p %p\n", 3297 bp, bp->b_bufobj->bo_object)); 3298 BUF_CHECK_MAPPED(bp); 3299 } 3300 3301 allocbuf(bp, size); 3302 bp->b_flags &= ~B_DONE; 3303 } 3304 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 3305 BUF_ASSERT_HELD(bp); 3306end: 3307 KASSERT(bp->b_bufobj == bo, 3308 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 3309 return (bp); 3310} 3311 3312/* 3313 * Get an empty, disassociated buffer of given size. The buffer is initially 3314 * set to B_INVAL. 3315 */ 3316struct buf * 3317geteblk(int size, int flags) 3318{ 3319 struct buf *bp; 3320 int maxsize; 3321 3322 maxsize = (size + BKVAMASK) & ~BKVAMASK; 3323 while ((bp = getnewbuf(NULL, 0, 0, size, maxsize, flags)) == NULL) { 3324 if ((flags & GB_NOWAIT_BD) && 3325 (curthread->td_pflags & TDP_BUFNEED) != 0) 3326 return (NULL); 3327 } 3328 allocbuf(bp, size); 3329 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 3330 BUF_ASSERT_HELD(bp); 3331 return (bp); 3332} 3333 3334 3335/* 3336 * This code constitutes the buffer memory from either anonymous system 3337 * memory (in the case of non-VMIO operations) or from an associated 3338 * VM object (in the case of VMIO operations). This code is able to 3339 * resize a buffer up or down. 3340 * 3341 * Note that this code is tricky, and has many complications to resolve 3342 * deadlock or inconsistant data situations. Tread lightly!!! 3343 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 3344 * the caller. Calling this code willy nilly can result in the loss of data. 3345 * 3346 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 3347 * B_CACHE for the non-VMIO case. 3348 */ 3349 3350int 3351allocbuf(struct buf *bp, int size) 3352{ 3353 int newbsize, mbsize; 3354 int i; 3355 3356 BUF_ASSERT_HELD(bp); 3357 3358 if (bp->b_kvasize < size) 3359 panic("allocbuf: buffer too small"); 3360 3361 if ((bp->b_flags & B_VMIO) == 0) { 3362 caddr_t origbuf; 3363 int origbufsize; 3364 /* 3365 * Just get anonymous memory from the kernel. Don't 3366 * mess with B_CACHE. 3367 */ 3368 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3369 if (bp->b_flags & B_MALLOC) 3370 newbsize = mbsize; 3371 else 3372 newbsize = round_page(size); 3373 3374 if (newbsize < bp->b_bufsize) { 3375 /* 3376 * malloced buffers are not shrunk 3377 */ 3378 if (bp->b_flags & B_MALLOC) { 3379 if (newbsize) { 3380 bp->b_bcount = size; 3381 } else { 3382 free(bp->b_data, M_BIOBUF); 3383 if (bp->b_bufsize) { 3384 atomic_subtract_long( 3385 &bufmallocspace, 3386 bp->b_bufsize); 3387 bufspacewakeup(); 3388 bp->b_bufsize = 0; 3389 } 3390 bp->b_saveaddr = bp->b_kvabase; 3391 bp->b_data = bp->b_saveaddr; 3392 bp->b_bcount = 0; 3393 bp->b_flags &= ~B_MALLOC; 3394 } 3395 return 1; 3396 } 3397 vm_hold_free_pages(bp, newbsize); 3398 } else if (newbsize > bp->b_bufsize) { 3399 /* 3400 * We only use malloced memory on the first allocation. 3401 * and revert to page-allocated memory when the buffer 3402 * grows. 3403 */ 3404 /* 3405 * There is a potential smp race here that could lead 3406 * to bufmallocspace slightly passing the max. It 3407 * is probably extremely rare and not worth worrying 3408 * over. 3409 */ 3410 if ( (bufmallocspace < maxbufmallocspace) && 3411 (bp->b_bufsize == 0) && 3412 (mbsize <= PAGE_SIZE/2)) { 3413 3414 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 3415 bp->b_bufsize = mbsize; 3416 bp->b_bcount = size; 3417 bp->b_flags |= B_MALLOC; 3418 atomic_add_long(&bufmallocspace, mbsize); 3419 return 1; 3420 } 3421 origbuf = NULL; 3422 origbufsize = 0; 3423 /* 3424 * If the buffer is growing on its other-than-first allocation, 3425 * then we revert to the page-allocation scheme. 3426 */ 3427 if (bp->b_flags & B_MALLOC) { 3428 origbuf = bp->b_data; 3429 origbufsize = bp->b_bufsize; 3430 bp->b_data = bp->b_kvabase; 3431 if (bp->b_bufsize) { 3432 atomic_subtract_long(&bufmallocspace, 3433 bp->b_bufsize); 3434 bufspacewakeup(); 3435 bp->b_bufsize = 0; 3436 } 3437 bp->b_flags &= ~B_MALLOC; 3438 newbsize = round_page(newbsize); 3439 } 3440 vm_hold_load_pages( 3441 bp, 3442 (vm_offset_t) bp->b_data + bp->b_bufsize, 3443 (vm_offset_t) bp->b_data + newbsize); 3444 if (origbuf) { 3445 bcopy(origbuf, bp->b_data, origbufsize); 3446 free(origbuf, M_BIOBUF); 3447 } 3448 } 3449 } else { 3450 int desiredpages; 3451 3452 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3453 desiredpages = (size == 0) ? 0 : 3454 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 3455 3456 if (bp->b_flags & B_MALLOC) 3457 panic("allocbuf: VMIO buffer can't be malloced"); 3458 /* 3459 * Set B_CACHE initially if buffer is 0 length or will become 3460 * 0-length. 3461 */ 3462 if (size == 0 || bp->b_bufsize == 0) 3463 bp->b_flags |= B_CACHE; 3464 3465 if (newbsize < bp->b_bufsize) { 3466 /* 3467 * DEV_BSIZE aligned new buffer size is less then the 3468 * DEV_BSIZE aligned existing buffer size. Figure out 3469 * if we have to remove any pages. 3470 */ 3471 if (desiredpages < bp->b_npages) { 3472 vm_page_t m; 3473 3474 if ((bp->b_flags & B_UNMAPPED) == 0) { 3475 BUF_CHECK_MAPPED(bp); 3476 pmap_qremove((vm_offset_t)trunc_page( 3477 (vm_offset_t)bp->b_data) + 3478 (desiredpages << PAGE_SHIFT), 3479 (bp->b_npages - desiredpages)); 3480 } else 3481 BUF_CHECK_UNMAPPED(bp); 3482 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 3483 for (i = desiredpages; i < bp->b_npages; i++) { 3484 /* 3485 * the page is not freed here -- it 3486 * is the responsibility of 3487 * vnode_pager_setsize 3488 */ 3489 m = bp->b_pages[i]; 3490 KASSERT(m != bogus_page, 3491 ("allocbuf: bogus page found")); 3492 while (vm_page_sleep_if_busy(m, 3493 "biodep")) 3494 continue; 3495 3496 bp->b_pages[i] = NULL; 3497 vm_page_lock(m); 3498 vm_page_unwire(m, 0); 3499 vm_page_unlock(m); 3500 } 3501 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 3502 bp->b_npages = desiredpages; 3503 } 3504 } else if (size > bp->b_bcount) { 3505 /* 3506 * We are growing the buffer, possibly in a 3507 * byte-granular fashion. 3508 */ 3509 vm_object_t obj; 3510 vm_offset_t toff; 3511 vm_offset_t tinc; 3512 3513 /* 3514 * Step 1, bring in the VM pages from the object, 3515 * allocating them if necessary. We must clear 3516 * B_CACHE if these pages are not valid for the 3517 * range covered by the buffer. 3518 */ 3519 3520 obj = bp->b_bufobj->bo_object; 3521 3522 VM_OBJECT_WLOCK(obj); 3523 while (bp->b_npages < desiredpages) { 3524 vm_page_t m; 3525 3526 /* 3527 * We must allocate system pages since blocking 3528 * here could interfere with paging I/O, no 3529 * matter which process we are. 3530 * 3531 * Only exclusive busy can be tested here. 3532 * Blocking on shared busy might lead to 3533 * deadlocks once allocbuf() is called after 3534 * pages are vfs_busy_pages(). 3535 */ 3536 m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) + 3537 bp->b_npages, VM_ALLOC_NOBUSY | 3538 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED | 3539 VM_ALLOC_IGN_SBUSY | 3540 VM_ALLOC_COUNT(desiredpages - bp->b_npages)); 3541 if (m->valid == 0) 3542 bp->b_flags &= ~B_CACHE; 3543 bp->b_pages[bp->b_npages] = m; 3544 ++bp->b_npages; 3545 } 3546 3547 /* 3548 * Step 2. We've loaded the pages into the buffer, 3549 * we have to figure out if we can still have B_CACHE 3550 * set. Note that B_CACHE is set according to the 3551 * byte-granular range ( bcount and size ), new the 3552 * aligned range ( newbsize ). 3553 * 3554 * The VM test is against m->valid, which is DEV_BSIZE 3555 * aligned. Needless to say, the validity of the data 3556 * needs to also be DEV_BSIZE aligned. Note that this 3557 * fails with NFS if the server or some other client 3558 * extends the file's EOF. If our buffer is resized, 3559 * B_CACHE may remain set! XXX 3560 */ 3561 3562 toff = bp->b_bcount; 3563 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 3564 3565 while ((bp->b_flags & B_CACHE) && toff < size) { 3566 vm_pindex_t pi; 3567 3568 if (tinc > (size - toff)) 3569 tinc = size - toff; 3570 3571 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 3572 PAGE_SHIFT; 3573 3574 vfs_buf_test_cache( 3575 bp, 3576 bp->b_offset, 3577 toff, 3578 tinc, 3579 bp->b_pages[pi] 3580 ); 3581 toff += tinc; 3582 tinc = PAGE_SIZE; 3583 } 3584 VM_OBJECT_WUNLOCK(obj); 3585 3586 /* 3587 * Step 3, fixup the KVM pmap. 3588 */ 3589 if ((bp->b_flags & B_UNMAPPED) == 0) 3590 bpmap_qenter(bp); 3591 else 3592 BUF_CHECK_UNMAPPED(bp); 3593 } 3594 } 3595 if (newbsize < bp->b_bufsize) 3596 bufspacewakeup(); 3597 bp->b_bufsize = newbsize; /* actual buffer allocation */ 3598 bp->b_bcount = size; /* requested buffer size */ 3599 return 1; 3600} 3601 3602extern int inflight_transient_maps; 3603 3604void 3605biodone(struct bio *bp) 3606{ 3607 struct mtx *mtxp; 3608 void (*done)(struct bio *); 3609 vm_offset_t start, end; 3610 3611 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) { 3612 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING; 3613 bp->bio_flags |= BIO_UNMAPPED; 3614 start = trunc_page((vm_offset_t)bp->bio_data); 3615 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length); 3616 pmap_qremove(start, OFF_TO_IDX(end - start)); 3617 vmem_free(transient_arena, start, end - start); 3618 atomic_add_int(&inflight_transient_maps, -1); 3619 } 3620 done = bp->bio_done; 3621 if (done == NULL) { 3622 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3623 mtx_lock(mtxp); 3624 bp->bio_flags |= BIO_DONE; 3625 wakeup(bp); 3626 mtx_unlock(mtxp); 3627 } else { 3628 bp->bio_flags |= BIO_DONE; 3629 done(bp); 3630 } 3631} 3632 3633/* 3634 * Wait for a BIO to finish. 3635 */ 3636int 3637biowait(struct bio *bp, const char *wchan) 3638{ 3639 struct mtx *mtxp; 3640 3641 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3642 mtx_lock(mtxp); 3643 while ((bp->bio_flags & BIO_DONE) == 0) 3644 msleep(bp, mtxp, PRIBIO, wchan, 0); 3645 mtx_unlock(mtxp); 3646 if (bp->bio_error != 0) 3647 return (bp->bio_error); 3648 if (!(bp->bio_flags & BIO_ERROR)) 3649 return (0); 3650 return (EIO); 3651} 3652 3653void 3654biofinish(struct bio *bp, struct devstat *stat, int error) 3655{ 3656 3657 if (error) { 3658 bp->bio_error = error; 3659 bp->bio_flags |= BIO_ERROR; 3660 } 3661 if (stat != NULL) 3662 devstat_end_transaction_bio(stat, bp); 3663 biodone(bp); 3664} 3665 3666/* 3667 * bufwait: 3668 * 3669 * Wait for buffer I/O completion, returning error status. The buffer 3670 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3671 * error and cleared. 3672 */ 3673int 3674bufwait(struct buf *bp) 3675{ 3676 if (bp->b_iocmd == BIO_READ) 3677 bwait(bp, PRIBIO, "biord"); 3678 else 3679 bwait(bp, PRIBIO, "biowr"); 3680 if (bp->b_flags & B_EINTR) { 3681 bp->b_flags &= ~B_EINTR; 3682 return (EINTR); 3683 } 3684 if (bp->b_ioflags & BIO_ERROR) { 3685 return (bp->b_error ? bp->b_error : EIO); 3686 } else { 3687 return (0); 3688 } 3689} 3690 3691 /* 3692 * Call back function from struct bio back up to struct buf. 3693 */ 3694static void 3695bufdonebio(struct bio *bip) 3696{ 3697 struct buf *bp; 3698 3699 bp = bip->bio_caller2; 3700 bp->b_resid = bp->b_bcount - bip->bio_completed; 3701 bp->b_resid = bip->bio_resid; /* XXX: remove */ 3702 bp->b_ioflags = bip->bio_flags; 3703 bp->b_error = bip->bio_error; 3704 if (bp->b_error) 3705 bp->b_ioflags |= BIO_ERROR; 3706 bufdone(bp); 3707 g_destroy_bio(bip); 3708} 3709 3710void 3711dev_strategy(struct cdev *dev, struct buf *bp) 3712{ 3713 struct cdevsw *csw; 3714 int ref; 3715 3716 KASSERT(dev->si_refcount > 0, 3717 ("dev_strategy on un-referenced struct cdev *(%s) %p", 3718 devtoname(dev), dev)); 3719 3720 csw = dev_refthread(dev, &ref); 3721 dev_strategy_csw(dev, csw, bp); 3722 dev_relthread(dev, ref); 3723} 3724 3725void 3726dev_strategy_csw(struct cdev *dev, struct cdevsw *csw, struct buf *bp) 3727{ 3728 struct bio *bip; 3729 3730 KASSERT(bp->b_iocmd == BIO_READ || bp->b_iocmd == BIO_WRITE, 3731 ("b_iocmd botch")); 3732 KASSERT(((dev->si_flags & SI_ETERNAL) != 0 && csw != NULL) || 3733 dev->si_threadcount > 0, 3734 ("dev_strategy_csw threadcount cdev *(%s) %p", devtoname(dev), 3735 dev)); 3736 if (csw == NULL) { 3737 bp->b_error = ENXIO; 3738 bp->b_ioflags = BIO_ERROR; 3739 bufdone(bp); 3740 return; 3741 } 3742 for (;;) { 3743 bip = g_new_bio(); 3744 if (bip != NULL) 3745 break; 3746 /* Try again later */ 3747 tsleep(&bp, PRIBIO, "dev_strat", hz/10); 3748 } 3749 bip->bio_cmd = bp->b_iocmd; 3750 bip->bio_offset = bp->b_iooffset; 3751 bip->bio_length = bp->b_bcount; 3752 bip->bio_bcount = bp->b_bcount; /* XXX: remove */ 3753 bdata2bio(bp, bip); 3754 bip->bio_done = bufdonebio; 3755 bip->bio_caller2 = bp; 3756 bip->bio_dev = dev; 3757 (*csw->d_strategy)(bip); 3758} 3759 3760/* 3761 * bufdone: 3762 * 3763 * Finish I/O on a buffer, optionally calling a completion function. 3764 * This is usually called from an interrupt so process blocking is 3765 * not allowed. 3766 * 3767 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3768 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3769 * assuming B_INVAL is clear. 3770 * 3771 * For the VMIO case, we set B_CACHE if the op was a read and no 3772 * read error occured, or if the op was a write. B_CACHE is never 3773 * set if the buffer is invalid or otherwise uncacheable. 3774 * 3775 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3776 * initiator to leave B_INVAL set to brelse the buffer out of existance 3777 * in the biodone routine. 3778 */ 3779void 3780bufdone(struct buf *bp) 3781{ 3782 struct bufobj *dropobj; 3783 void (*biodone)(struct buf *); 3784 3785 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 3786 dropobj = NULL; 3787 3788 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 3789 BUF_ASSERT_HELD(bp); 3790 3791 runningbufwakeup(bp); 3792 if (bp->b_iocmd == BIO_WRITE) 3793 dropobj = bp->b_bufobj; 3794 /* call optional completion function if requested */ 3795 if (bp->b_iodone != NULL) { 3796 biodone = bp->b_iodone; 3797 bp->b_iodone = NULL; 3798 (*biodone) (bp); 3799 if (dropobj) 3800 bufobj_wdrop(dropobj); 3801 return; 3802 } 3803 3804 bufdone_finish(bp); 3805 3806 if (dropobj) 3807 bufobj_wdrop(dropobj); 3808} 3809 3810void 3811bufdone_finish(struct buf *bp) 3812{ 3813 BUF_ASSERT_HELD(bp); 3814 3815 if (!LIST_EMPTY(&bp->b_dep)) 3816 buf_complete(bp); 3817 3818 if (bp->b_flags & B_VMIO) { 3819 vm_ooffset_t foff; 3820 vm_page_t m; 3821 vm_object_t obj; 3822 struct vnode *vp; 3823 int bogus, i, iosize; 3824 3825 obj = bp->b_bufobj->bo_object; 3826 KASSERT(obj->paging_in_progress >= bp->b_npages, 3827 ("biodone_finish: paging in progress(%d) < b_npages(%d)", 3828 obj->paging_in_progress, bp->b_npages)); 3829 3830 vp = bp->b_vp; 3831 KASSERT(vp->v_holdcnt > 0, 3832 ("biodone_finish: vnode %p has zero hold count", vp)); 3833 KASSERT(vp->v_object != NULL, 3834 ("biodone_finish: vnode %p has no vm_object", vp)); 3835 3836 foff = bp->b_offset; 3837 KASSERT(bp->b_offset != NOOFFSET, 3838 ("biodone_finish: bp %p has no buffer offset", bp)); 3839 3840 /* 3841 * Set B_CACHE if the op was a normal read and no error 3842 * occured. B_CACHE is set for writes in the b*write() 3843 * routines. 3844 */ 3845 iosize = bp->b_bcount - bp->b_resid; 3846 if (bp->b_iocmd == BIO_READ && 3847 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 3848 !(bp->b_ioflags & BIO_ERROR)) { 3849 bp->b_flags |= B_CACHE; 3850 } 3851 bogus = 0; 3852 VM_OBJECT_WLOCK(obj); 3853 for (i = 0; i < bp->b_npages; i++) { 3854 int bogusflag = 0; 3855 int resid; 3856 3857 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 3858 if (resid > iosize) 3859 resid = iosize; 3860 3861 /* 3862 * cleanup bogus pages, restoring the originals 3863 */ 3864 m = bp->b_pages[i]; 3865 if (m == bogus_page) { 3866 bogus = bogusflag = 1; 3867 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3868 if (m == NULL) 3869 panic("biodone: page disappeared!"); 3870 bp->b_pages[i] = m; 3871 } 3872 KASSERT(OFF_TO_IDX(foff) == m->pindex, 3873 ("biodone_finish: foff(%jd)/pindex(%ju) mismatch", 3874 (intmax_t)foff, (uintmax_t)m->pindex)); 3875 3876 /* 3877 * In the write case, the valid and clean bits are 3878 * already changed correctly ( see bdwrite() ), so we 3879 * only need to do this here in the read case. 3880 */ 3881 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 3882 KASSERT((m->dirty & vm_page_bits(foff & 3883 PAGE_MASK, resid)) == 0, ("bufdone_finish:" 3884 " page %p has unexpected dirty bits", m)); 3885 vfs_page_set_valid(bp, foff, m); 3886 } 3887 3888 vm_page_sunbusy(m); 3889 vm_object_pip_subtract(obj, 1); 3890 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3891 iosize -= resid; 3892 } 3893 vm_object_pip_wakeupn(obj, 0); 3894 VM_OBJECT_WUNLOCK(obj); 3895 if (bogus && (bp->b_flags & B_UNMAPPED) == 0) { 3896 BUF_CHECK_MAPPED(bp); 3897 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3898 bp->b_pages, bp->b_npages); 3899 } 3900 } 3901 3902 /* 3903 * For asynchronous completions, release the buffer now. The brelse 3904 * will do a wakeup there if necessary - so no need to do a wakeup 3905 * here in the async case. The sync case always needs to do a wakeup. 3906 */ 3907 3908 if (bp->b_flags & B_ASYNC) { 3909 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 3910 brelse(bp); 3911 else 3912 bqrelse(bp); 3913 } else 3914 bdone(bp); 3915} 3916 3917/* 3918 * This routine is called in lieu of iodone in the case of 3919 * incomplete I/O. This keeps the busy status for pages 3920 * consistant. 3921 */ 3922void 3923vfs_unbusy_pages(struct buf *bp) 3924{ 3925 int i; 3926 vm_object_t obj; 3927 vm_page_t m; 3928 3929 runningbufwakeup(bp); 3930 if (!(bp->b_flags & B_VMIO)) 3931 return; 3932 3933 obj = bp->b_bufobj->bo_object; 3934 VM_OBJECT_WLOCK(obj); 3935 for (i = 0; i < bp->b_npages; i++) { 3936 m = bp->b_pages[i]; 3937 if (m == bogus_page) { 3938 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 3939 if (!m) 3940 panic("vfs_unbusy_pages: page missing\n"); 3941 bp->b_pages[i] = m; 3942 if ((bp->b_flags & B_UNMAPPED) == 0) { 3943 BUF_CHECK_MAPPED(bp); 3944 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3945 bp->b_pages, bp->b_npages); 3946 } else 3947 BUF_CHECK_UNMAPPED(bp); 3948 } 3949 vm_object_pip_subtract(obj, 1); 3950 vm_page_sunbusy(m); 3951 } 3952 vm_object_pip_wakeupn(obj, 0); 3953 VM_OBJECT_WUNLOCK(obj); 3954} 3955 3956/* 3957 * vfs_page_set_valid: 3958 * 3959 * Set the valid bits in a page based on the supplied offset. The 3960 * range is restricted to the buffer's size. 3961 * 3962 * This routine is typically called after a read completes. 3963 */ 3964static void 3965vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3966{ 3967 vm_ooffset_t eoff; 3968 3969 /* 3970 * Compute the end offset, eoff, such that [off, eoff) does not span a 3971 * page boundary and eoff is not greater than the end of the buffer. 3972 * The end of the buffer, in this case, is our file EOF, not the 3973 * allocation size of the buffer. 3974 */ 3975 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 3976 if (eoff > bp->b_offset + bp->b_bcount) 3977 eoff = bp->b_offset + bp->b_bcount; 3978 3979 /* 3980 * Set valid range. This is typically the entire buffer and thus the 3981 * entire page. 3982 */ 3983 if (eoff > off) 3984 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off); 3985} 3986 3987/* 3988 * vfs_page_set_validclean: 3989 * 3990 * Set the valid bits and clear the dirty bits in a page based on the 3991 * supplied offset. The range is restricted to the buffer's size. 3992 */ 3993static void 3994vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3995{ 3996 vm_ooffset_t soff, eoff; 3997 3998 /* 3999 * Start and end offsets in buffer. eoff - soff may not cross a 4000 * page boundry or cross the end of the buffer. The end of the 4001 * buffer, in this case, is our file EOF, not the allocation size 4002 * of the buffer. 4003 */ 4004 soff = off; 4005 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4006 if (eoff > bp->b_offset + bp->b_bcount) 4007 eoff = bp->b_offset + bp->b_bcount; 4008 4009 /* 4010 * Set valid range. This is typically the entire buffer and thus the 4011 * entire page. 4012 */ 4013 if (eoff > soff) { 4014 vm_page_set_validclean( 4015 m, 4016 (vm_offset_t) (soff & PAGE_MASK), 4017 (vm_offset_t) (eoff - soff) 4018 ); 4019 } 4020} 4021 4022/* 4023 * Ensure that all buffer pages are not exclusive busied. If any page is 4024 * exclusive busy, drain it. 4025 */ 4026void 4027vfs_drain_busy_pages(struct buf *bp) 4028{ 4029 vm_page_t m; 4030 int i, last_busied; 4031 4032 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object); 4033 last_busied = 0; 4034 for (i = 0; i < bp->b_npages; i++) { 4035 m = bp->b_pages[i]; 4036 if (vm_page_xbusied(m)) { 4037 for (; last_busied < i; last_busied++) 4038 vm_page_sbusy(bp->b_pages[last_busied]); 4039 while (vm_page_xbusied(m)) { 4040 vm_page_lock(m); 4041 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4042 vm_page_busy_sleep(m, "vbpage"); 4043 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4044 } 4045 } 4046 } 4047 for (i = 0; i < last_busied; i++) 4048 vm_page_sunbusy(bp->b_pages[i]); 4049} 4050 4051/* 4052 * This routine is called before a device strategy routine. 4053 * It is used to tell the VM system that paging I/O is in 4054 * progress, and treat the pages associated with the buffer 4055 * almost as being exclusive busy. Also the object paging_in_progress 4056 * flag is handled to make sure that the object doesn't become 4057 * inconsistant. 4058 * 4059 * Since I/O has not been initiated yet, certain buffer flags 4060 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 4061 * and should be ignored. 4062 */ 4063void 4064vfs_busy_pages(struct buf *bp, int clear_modify) 4065{ 4066 int i, bogus; 4067 vm_object_t obj; 4068 vm_ooffset_t foff; 4069 vm_page_t m; 4070 4071 if (!(bp->b_flags & B_VMIO)) 4072 return; 4073 4074 obj = bp->b_bufobj->bo_object; 4075 foff = bp->b_offset; 4076 KASSERT(bp->b_offset != NOOFFSET, 4077 ("vfs_busy_pages: no buffer offset")); 4078 VM_OBJECT_WLOCK(obj); 4079 vfs_drain_busy_pages(bp); 4080 if (bp->b_bufsize != 0) 4081 vfs_setdirty_locked_object(bp); 4082 bogus = 0; 4083 for (i = 0; i < bp->b_npages; i++) { 4084 m = bp->b_pages[i]; 4085 4086 if ((bp->b_flags & B_CLUSTER) == 0) { 4087 vm_object_pip_add(obj, 1); 4088 vm_page_sbusy(m); 4089 } 4090 /* 4091 * When readying a buffer for a read ( i.e 4092 * clear_modify == 0 ), it is important to do 4093 * bogus_page replacement for valid pages in 4094 * partially instantiated buffers. Partially 4095 * instantiated buffers can, in turn, occur when 4096 * reconstituting a buffer from its VM backing store 4097 * base. We only have to do this if B_CACHE is 4098 * clear ( which causes the I/O to occur in the 4099 * first place ). The replacement prevents the read 4100 * I/O from overwriting potentially dirty VM-backed 4101 * pages. XXX bogus page replacement is, uh, bogus. 4102 * It may not work properly with small-block devices. 4103 * We need to find a better way. 4104 */ 4105 if (clear_modify) { 4106 pmap_remove_write(m); 4107 vfs_page_set_validclean(bp, foff, m); 4108 } else if (m->valid == VM_PAGE_BITS_ALL && 4109 (bp->b_flags & B_CACHE) == 0) { 4110 bp->b_pages[i] = bogus_page; 4111 bogus++; 4112 } 4113 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4114 } 4115 VM_OBJECT_WUNLOCK(obj); 4116 if (bogus && (bp->b_flags & B_UNMAPPED) == 0) { 4117 BUF_CHECK_MAPPED(bp); 4118 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4119 bp->b_pages, bp->b_npages); 4120 } 4121} 4122 4123/* 4124 * vfs_bio_set_valid: 4125 * 4126 * Set the range within the buffer to valid. The range is 4127 * relative to the beginning of the buffer, b_offset. Note that 4128 * b_offset itself may be offset from the beginning of the first 4129 * page. 4130 */ 4131void 4132vfs_bio_set_valid(struct buf *bp, int base, int size) 4133{ 4134 int i, n; 4135 vm_page_t m; 4136 4137 if (!(bp->b_flags & B_VMIO)) 4138 return; 4139 4140 /* 4141 * Fixup base to be relative to beginning of first page. 4142 * Set initial n to be the maximum number of bytes in the 4143 * first page that can be validated. 4144 */ 4145 base += (bp->b_offset & PAGE_MASK); 4146 n = PAGE_SIZE - (base & PAGE_MASK); 4147 4148 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4149 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4150 m = bp->b_pages[i]; 4151 if (n > size) 4152 n = size; 4153 vm_page_set_valid_range(m, base & PAGE_MASK, n); 4154 base += n; 4155 size -= n; 4156 n = PAGE_SIZE; 4157 } 4158 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4159} 4160 4161/* 4162 * vfs_bio_clrbuf: 4163 * 4164 * If the specified buffer is a non-VMIO buffer, clear the entire 4165 * buffer. If the specified buffer is a VMIO buffer, clear and 4166 * validate only the previously invalid portions of the buffer. 4167 * This routine essentially fakes an I/O, so we need to clear 4168 * BIO_ERROR and B_INVAL. 4169 * 4170 * Note that while we only theoretically need to clear through b_bcount, 4171 * we go ahead and clear through b_bufsize. 4172 */ 4173void 4174vfs_bio_clrbuf(struct buf *bp) 4175{ 4176 int i, j, mask, sa, ea, slide; 4177 4178 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 4179 clrbuf(bp); 4180 return; 4181 } 4182 bp->b_flags &= ~B_INVAL; 4183 bp->b_ioflags &= ~BIO_ERROR; 4184 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4185 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 4186 (bp->b_offset & PAGE_MASK) == 0) { 4187 if (bp->b_pages[0] == bogus_page) 4188 goto unlock; 4189 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 4190 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object); 4191 if ((bp->b_pages[0]->valid & mask) == mask) 4192 goto unlock; 4193 if ((bp->b_pages[0]->valid & mask) == 0) { 4194 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize); 4195 bp->b_pages[0]->valid |= mask; 4196 goto unlock; 4197 } 4198 } 4199 sa = bp->b_offset & PAGE_MASK; 4200 slide = 0; 4201 for (i = 0; i < bp->b_npages; i++, sa = 0) { 4202 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize); 4203 ea = slide & PAGE_MASK; 4204 if (ea == 0) 4205 ea = PAGE_SIZE; 4206 if (bp->b_pages[i] == bogus_page) 4207 continue; 4208 j = sa / DEV_BSIZE; 4209 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 4210 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object); 4211 if ((bp->b_pages[i]->valid & mask) == mask) 4212 continue; 4213 if ((bp->b_pages[i]->valid & mask) == 0) 4214 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa); 4215 else { 4216 for (; sa < ea; sa += DEV_BSIZE, j++) { 4217 if ((bp->b_pages[i]->valid & (1 << j)) == 0) { 4218 pmap_zero_page_area(bp->b_pages[i], 4219 sa, DEV_BSIZE); 4220 } 4221 } 4222 } 4223 bp->b_pages[i]->valid |= mask; 4224 } 4225unlock: 4226 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4227 bp->b_resid = 0; 4228} 4229 4230void 4231vfs_bio_bzero_buf(struct buf *bp, int base, int size) 4232{ 4233 vm_page_t m; 4234 int i, n; 4235 4236 if ((bp->b_flags & B_UNMAPPED) == 0) { 4237 BUF_CHECK_MAPPED(bp); 4238 bzero(bp->b_data + base, size); 4239 } else { 4240 BUF_CHECK_UNMAPPED(bp); 4241 n = PAGE_SIZE - (base & PAGE_MASK); 4242 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4243 m = bp->b_pages[i]; 4244 if (n > size) 4245 n = size; 4246 pmap_zero_page_area(m, base & PAGE_MASK, n); 4247 base += n; 4248 size -= n; 4249 n = PAGE_SIZE; 4250 } 4251 } 4252} 4253 4254/* 4255 * vm_hold_load_pages and vm_hold_free_pages get pages into 4256 * a buffers address space. The pages are anonymous and are 4257 * not associated with a file object. 4258 */ 4259static void 4260vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4261{ 4262 vm_offset_t pg; 4263 vm_page_t p; 4264 int index; 4265 4266 BUF_CHECK_MAPPED(bp); 4267 4268 to = round_page(to); 4269 from = round_page(from); 4270 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4271 4272 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 4273tryagain: 4274 /* 4275 * note: must allocate system pages since blocking here 4276 * could interfere with paging I/O, no matter which 4277 * process we are. 4278 */ 4279 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ | 4280 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT)); 4281 if (p == NULL) { 4282 VM_WAIT; 4283 goto tryagain; 4284 } 4285 pmap_qenter(pg, &p, 1); 4286 bp->b_pages[index] = p; 4287 } 4288 bp->b_npages = index; 4289} 4290 4291/* Return pages associated with this buf to the vm system */ 4292static void 4293vm_hold_free_pages(struct buf *bp, int newbsize) 4294{ 4295 vm_offset_t from; 4296 vm_page_t p; 4297 int index, newnpages; 4298 4299 BUF_CHECK_MAPPED(bp); 4300 4301 from = round_page((vm_offset_t)bp->b_data + newbsize); 4302 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4303 if (bp->b_npages > newnpages) 4304 pmap_qremove(from, bp->b_npages - newnpages); 4305 for (index = newnpages; index < bp->b_npages; index++) { 4306 p = bp->b_pages[index]; 4307 bp->b_pages[index] = NULL; 4308 if (vm_page_sbusied(p)) 4309 printf("vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 4310 (intmax_t)bp->b_blkno, (intmax_t)bp->b_lblkno); 4311 p->wire_count--; 4312 vm_page_free(p); 4313 atomic_subtract_int(&cnt.v_wire_count, 1); 4314 } 4315 bp->b_npages = newnpages; 4316} 4317 4318/* 4319 * Map an IO request into kernel virtual address space. 4320 * 4321 * All requests are (re)mapped into kernel VA space. 4322 * Notice that we use b_bufsize for the size of the buffer 4323 * to be mapped. b_bcount might be modified by the driver. 4324 * 4325 * Note that even if the caller determines that the address space should 4326 * be valid, a race or a smaller-file mapped into a larger space may 4327 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 4328 * check the return value. 4329 */ 4330int 4331vmapbuf(struct buf *bp, int mapbuf) 4332{ 4333 caddr_t kva; 4334 vm_prot_t prot; 4335 int pidx; 4336 4337 if (bp->b_bufsize < 0) 4338 return (-1); 4339 prot = VM_PROT_READ; 4340 if (bp->b_iocmd == BIO_READ) 4341 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 4342 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 4343 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages, 4344 btoc(MAXPHYS))) < 0) 4345 return (-1); 4346 bp->b_npages = pidx; 4347 if (mapbuf || !unmapped_buf_allowed) { 4348 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx); 4349 kva = bp->b_saveaddr; 4350 bp->b_saveaddr = bp->b_data; 4351 bp->b_data = kva + (((vm_offset_t)bp->b_data) & PAGE_MASK); 4352 bp->b_flags &= ~B_UNMAPPED; 4353 } else { 4354 bp->b_flags |= B_UNMAPPED; 4355 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK; 4356 bp->b_saveaddr = bp->b_data; 4357 bp->b_data = unmapped_buf; 4358 } 4359 return(0); 4360} 4361 4362/* 4363 * Free the io map PTEs associated with this IO operation. 4364 * We also invalidate the TLB entries and restore the original b_addr. 4365 */ 4366void 4367vunmapbuf(struct buf *bp) 4368{ 4369 int npages; 4370 4371 npages = bp->b_npages; 4372 if (bp->b_flags & B_UNMAPPED) 4373 bp->b_flags &= ~B_UNMAPPED; 4374 else 4375 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 4376 vm_page_unhold_pages(bp->b_pages, npages); 4377 4378 bp->b_data = bp->b_saveaddr; 4379} 4380 4381void 4382bdone(struct buf *bp) 4383{ 4384 struct mtx *mtxp; 4385 4386 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4387 mtx_lock(mtxp); 4388 bp->b_flags |= B_DONE; 4389 wakeup(bp); 4390 mtx_unlock(mtxp); 4391} 4392 4393void 4394bwait(struct buf *bp, u_char pri, const char *wchan) 4395{ 4396 struct mtx *mtxp; 4397 4398 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4399 mtx_lock(mtxp); 4400 while ((bp->b_flags & B_DONE) == 0) 4401 msleep(bp, mtxp, pri, wchan, 0); 4402 mtx_unlock(mtxp); 4403} 4404 4405int 4406bufsync(struct bufobj *bo, int waitfor) 4407{ 4408 4409 return (VOP_FSYNC(bo->__bo_vnode, waitfor, curthread)); 4410} 4411 4412void 4413bufstrategy(struct bufobj *bo, struct buf *bp) 4414{ 4415 int i = 0; 4416 struct vnode *vp; 4417 4418 vp = bp->b_vp; 4419 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 4420 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 4421 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 4422 i = VOP_STRATEGY(vp, bp); 4423 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 4424} 4425 4426void 4427bufobj_wrefl(struct bufobj *bo) 4428{ 4429 4430 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4431 ASSERT_BO_WLOCKED(bo); 4432 bo->bo_numoutput++; 4433} 4434 4435void 4436bufobj_wref(struct bufobj *bo) 4437{ 4438 4439 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4440 BO_LOCK(bo); 4441 bo->bo_numoutput++; 4442 BO_UNLOCK(bo); 4443} 4444 4445void 4446bufobj_wdrop(struct bufobj *bo) 4447{ 4448 4449 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 4450 BO_LOCK(bo); 4451 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 4452 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 4453 bo->bo_flag &= ~BO_WWAIT; 4454 wakeup(&bo->bo_numoutput); 4455 } 4456 BO_UNLOCK(bo); 4457} 4458 4459int 4460bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 4461{ 4462 int error; 4463 4464 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 4465 ASSERT_BO_WLOCKED(bo); 4466 error = 0; 4467 while (bo->bo_numoutput) { 4468 bo->bo_flag |= BO_WWAIT; 4469 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo), 4470 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 4471 if (error) 4472 break; 4473 } 4474 return (error); 4475} 4476 4477void 4478bpin(struct buf *bp) 4479{ 4480 struct mtx *mtxp; 4481 4482 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4483 mtx_lock(mtxp); 4484 bp->b_pin_count++; 4485 mtx_unlock(mtxp); 4486} 4487 4488void 4489bunpin(struct buf *bp) 4490{ 4491 struct mtx *mtxp; 4492 4493 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4494 mtx_lock(mtxp); 4495 if (--bp->b_pin_count == 0) 4496 wakeup(bp); 4497 mtx_unlock(mtxp); 4498} 4499 4500void 4501bunpin_wait(struct buf *bp) 4502{ 4503 struct mtx *mtxp; 4504 4505 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4506 mtx_lock(mtxp); 4507 while (bp->b_pin_count > 0) 4508 msleep(bp, mtxp, PRIBIO, "bwunpin", 0); 4509 mtx_unlock(mtxp); 4510} 4511 4512/* 4513 * Set bio_data or bio_ma for struct bio from the struct buf. 4514 */ 4515void 4516bdata2bio(struct buf *bp, struct bio *bip) 4517{ 4518 4519 if ((bp->b_flags & B_UNMAPPED) != 0) { 4520 KASSERT(unmapped_buf_allowed, ("unmapped")); 4521 bip->bio_ma = bp->b_pages; 4522 bip->bio_ma_n = bp->b_npages; 4523 bip->bio_data = unmapped_buf; 4524 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 4525 bip->bio_flags |= BIO_UNMAPPED; 4526 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) / 4527 PAGE_SIZE == bp->b_npages, 4528 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset, 4529 (long long)bip->bio_length, bip->bio_ma_n)); 4530 } else { 4531 bip->bio_data = bp->b_data; 4532 bip->bio_ma = NULL; 4533 } 4534} 4535 4536#include "opt_ddb.h" 4537#ifdef DDB 4538#include <ddb/ddb.h> 4539 4540/* DDB command to show buffer data */ 4541DB_SHOW_COMMAND(buffer, db_show_buffer) 4542{ 4543 /* get args */ 4544 struct buf *bp = (struct buf *)addr; 4545 4546 if (!have_addr) { 4547 db_printf("usage: show buffer <addr>\n"); 4548 return; 4549 } 4550 4551 db_printf("buf at %p\n", bp); 4552 db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n", 4553 (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags, 4554 PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS); 4555 db_printf( 4556 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 4557 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, " 4558 "b_dep = %p\n", 4559 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 4560 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 4561 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first); 4562 if (bp->b_npages) { 4563 int i; 4564 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 4565 for (i = 0; i < bp->b_npages; i++) { 4566 vm_page_t m; 4567 m = bp->b_pages[i]; 4568 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 4569 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 4570 if ((i + 1) < bp->b_npages) 4571 db_printf(","); 4572 } 4573 db_printf("\n"); 4574 } 4575 db_printf(" "); 4576 BUF_LOCKPRINTINFO(bp); 4577} 4578 4579DB_SHOW_COMMAND(lockedbufs, lockedbufs) 4580{ 4581 struct buf *bp; 4582 int i; 4583 4584 for (i = 0; i < nbuf; i++) { 4585 bp = &buf[i]; 4586 if (BUF_ISLOCKED(bp)) { 4587 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4588 db_printf("\n"); 4589 } 4590 } 4591} 4592 4593DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 4594{ 4595 struct vnode *vp; 4596 struct buf *bp; 4597 4598 if (!have_addr) { 4599 db_printf("usage: show vnodebufs <addr>\n"); 4600 return; 4601 } 4602 vp = (struct vnode *)addr; 4603 db_printf("Clean buffers:\n"); 4604 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 4605 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4606 db_printf("\n"); 4607 } 4608 db_printf("Dirty buffers:\n"); 4609 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 4610 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4611 db_printf("\n"); 4612 } 4613} 4614 4615DB_COMMAND(countfreebufs, db_coundfreebufs) 4616{ 4617 struct buf *bp; 4618 int i, used = 0, nfree = 0; 4619 4620 if (have_addr) { 4621 db_printf("usage: countfreebufs\n"); 4622 return; 4623 } 4624 4625 for (i = 0; i < nbuf; i++) { 4626 bp = &buf[i]; 4627 if ((bp->b_flags & B_INFREECNT) != 0) 4628 nfree++; 4629 else 4630 used++; 4631 } 4632 4633 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 4634 nfree + used); 4635 db_printf("numfreebuffers is %d\n", numfreebuffers); 4636} 4637#endif /* DDB */ 4638