vfs_bio.c revision 285402
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 285402 2015-07-11 19:11:40Z 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 CTASSERT(MAXBCACHEBUF >= MAXBSIZE); 778 mtx_init(&bqclean, "bufq clean lock", NULL, MTX_DEF); 779 mtx_init(&bqdirty, "bufq dirty lock", NULL, MTX_DEF); 780 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 781 rw_init(&nblock, "needsbuffer lock"); 782 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 783 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF); 784 785 /* next, make a null set of free lists */ 786 for (i = 0; i < BUFFER_QUEUES; i++) 787 TAILQ_INIT(&bufqueues[i]); 788 789 /* finally, initialize each buffer header and stick on empty q */ 790 for (i = 0; i < nbuf; i++) { 791 bp = &buf[i]; 792 bzero(bp, sizeof *bp); 793 bp->b_flags = B_INVAL | B_INFREECNT; 794 bp->b_rcred = NOCRED; 795 bp->b_wcred = NOCRED; 796 bp->b_qindex = QUEUE_EMPTY; 797 bp->b_xflags = 0; 798 LIST_INIT(&bp->b_dep); 799 BUF_LOCKINIT(bp); 800 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 801#ifdef INVARIANTS 802 bq_len[QUEUE_EMPTY]++; 803#endif 804 } 805 806 /* 807 * maxbufspace is the absolute maximum amount of buffer space we are 808 * allowed to reserve in KVM and in real terms. The absolute maximum 809 * is nominally used by buf_daemon. hibufspace is the nominal maximum 810 * used by most other processes. The differential is required to 811 * ensure that buf_daemon is able to run when other processes might 812 * be blocked waiting for buffer space. 813 * 814 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 815 * this may result in KVM fragmentation which is not handled optimally 816 * by the system. 817 */ 818 maxbufspace = (long)nbuf * BKVASIZE; 819 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - MAXBCACHEBUF * 10); 820 lobufspace = hibufspace - MAXBCACHEBUF; 821 822 /* 823 * Note: The 16 MiB upper limit for hirunningspace was chosen 824 * arbitrarily and may need further tuning. It corresponds to 825 * 128 outstanding write IO requests (if IO size is 128 KiB), 826 * which fits with many RAID controllers' tagged queuing limits. 827 * The lower 1 MiB limit is the historical upper limit for 828 * hirunningspace. 829 */ 830 hirunningspace = lmax(lmin(roundup(hibufspace / 64, MAXBCACHEBUF), 831 16 * 1024 * 1024), 1024 * 1024); 832 lorunningspace = roundup((hirunningspace * 2) / 3, MAXBCACHEBUF); 833 834/* 835 * Limit the amount of malloc memory since it is wired permanently into 836 * the kernel space. Even though this is accounted for in the buffer 837 * allocation, we don't want the malloced region to grow uncontrolled. 838 * The malloc scheme improves memory utilization significantly on average 839 * (small) directories. 840 */ 841 maxbufmallocspace = hibufspace / 20; 842 843/* 844 * Reduce the chance of a deadlock occuring by limiting the number 845 * of delayed-write dirty buffers we allow to stack up. 846 */ 847 hidirtybuffers = nbuf / 4 + 20; 848 dirtybufthresh = hidirtybuffers * 9 / 10; 849 numdirtybuffers = 0; 850/* 851 * To support extreme low-memory systems, make sure hidirtybuffers cannot 852 * eat up all available buffer space. This occurs when our minimum cannot 853 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 854 * BKVASIZE'd buffers. 855 */ 856 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 857 hidirtybuffers >>= 1; 858 } 859 lodirtybuffers = hidirtybuffers / 2; 860 861/* 862 * Try to keep the number of free buffers in the specified range, 863 * and give special processes (e.g. like buf_daemon) access to an 864 * emergency reserve. 865 */ 866 lofreebuffers = nbuf / 18 + 5; 867 hifreebuffers = 2 * lofreebuffers; 868 numfreebuffers = nbuf; 869 870 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ | 871 VM_ALLOC_NORMAL | VM_ALLOC_WIRED); 872 unmapped_buf = (caddr_t)kva_alloc(MAXPHYS); 873} 874 875#ifdef INVARIANTS 876static inline void 877vfs_buf_check_mapped(struct buf *bp) 878{ 879 880 KASSERT((bp->b_flags & B_UNMAPPED) == 0, 881 ("mapped buf %p %x", bp, bp->b_flags)); 882 KASSERT(bp->b_kvabase != unmapped_buf, 883 ("mapped buf: b_kvabase was not updated %p", bp)); 884 KASSERT(bp->b_data != unmapped_buf, 885 ("mapped buf: b_data was not updated %p", bp)); 886} 887 888static inline void 889vfs_buf_check_unmapped(struct buf *bp) 890{ 891 892 KASSERT((bp->b_flags & B_UNMAPPED) == B_UNMAPPED, 893 ("unmapped buf %p %x", bp, bp->b_flags)); 894 KASSERT(bp->b_kvabase == unmapped_buf, 895 ("unmapped buf: corrupted b_kvabase %p", bp)); 896 KASSERT(bp->b_data == unmapped_buf, 897 ("unmapped buf: corrupted b_data %p", bp)); 898} 899 900#define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp) 901#define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp) 902#else 903#define BUF_CHECK_MAPPED(bp) do {} while (0) 904#define BUF_CHECK_UNMAPPED(bp) do {} while (0) 905#endif 906 907static void 908bpmap_qenter(struct buf *bp) 909{ 910 911 BUF_CHECK_MAPPED(bp); 912 913 /* 914 * bp->b_data is relative to bp->b_offset, but 915 * bp->b_offset may be offset into the first page. 916 */ 917 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data); 918 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages); 919 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 920 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 921} 922 923/* 924 * bfreekva() - free the kva allocation for a buffer. 925 * 926 * Since this call frees up buffer space, we call bufspacewakeup(). 927 */ 928static void 929bfreekva(struct buf *bp) 930{ 931 932 if (bp->b_kvasize == 0) 933 return; 934 935 atomic_add_int(&buffreekvacnt, 1); 936 atomic_subtract_long(&bufspace, bp->b_kvasize); 937 if ((bp->b_flags & B_UNMAPPED) == 0) { 938 BUF_CHECK_MAPPED(bp); 939 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, 940 bp->b_kvasize); 941 } else { 942 BUF_CHECK_UNMAPPED(bp); 943 if ((bp->b_flags & B_KVAALLOC) != 0) { 944 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvaalloc, 945 bp->b_kvasize); 946 } 947 atomic_subtract_long(&unmapped_bufspace, bp->b_kvasize); 948 bp->b_flags &= ~(B_UNMAPPED | B_KVAALLOC); 949 } 950 bp->b_kvasize = 0; 951 bufspacewakeup(); 952} 953 954/* 955 * binsfree: 956 * 957 * Insert the buffer into the appropriate free list. 958 */ 959static void 960binsfree(struct buf *bp, int qindex) 961{ 962 struct mtx *olock, *nlock; 963 964 BUF_ASSERT_XLOCKED(bp); 965 966 nlock = bqlock(qindex); 967 /* Handle delayed bremfree() processing. */ 968 if (bp->b_flags & B_REMFREE) { 969 olock = bqlock(bp->b_qindex); 970 mtx_lock(olock); 971 bremfreel(bp); 972 if (olock != nlock) { 973 mtx_unlock(olock); 974 mtx_lock(nlock); 975 } 976 } else 977 mtx_lock(nlock); 978 979 if (bp->b_qindex != QUEUE_NONE) 980 panic("binsfree: free buffer onto another queue???"); 981 982 bp->b_qindex = qindex; 983 if (bp->b_flags & B_AGE) 984 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 985 else 986 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 987#ifdef INVARIANTS 988 bq_len[bp->b_qindex]++; 989#endif 990 mtx_unlock(nlock); 991 992 /* 993 * Something we can maybe free or reuse. 994 */ 995 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 996 bufspacewakeup(); 997 998 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI)) 999 bufcountadd(bp); 1000} 1001 1002/* 1003 * bremfree: 1004 * 1005 * Mark the buffer for removal from the appropriate free list. 1006 * 1007 */ 1008void 1009bremfree(struct buf *bp) 1010{ 1011 1012 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1013 KASSERT((bp->b_flags & B_REMFREE) == 0, 1014 ("bremfree: buffer %p already marked for delayed removal.", bp)); 1015 KASSERT(bp->b_qindex != QUEUE_NONE, 1016 ("bremfree: buffer %p not on a queue.", bp)); 1017 BUF_ASSERT_XLOCKED(bp); 1018 1019 bp->b_flags |= B_REMFREE; 1020 bufcountsub(bp); 1021} 1022 1023/* 1024 * bremfreef: 1025 * 1026 * Force an immediate removal from a free list. Used only in nfs when 1027 * it abuses the b_freelist pointer. 1028 */ 1029void 1030bremfreef(struct buf *bp) 1031{ 1032 struct mtx *qlock; 1033 1034 qlock = bqlock(bp->b_qindex); 1035 mtx_lock(qlock); 1036 bremfreel(bp); 1037 mtx_unlock(qlock); 1038} 1039 1040/* 1041 * bremfreel: 1042 * 1043 * Removes a buffer from the free list, must be called with the 1044 * correct qlock held. 1045 */ 1046static void 1047bremfreel(struct buf *bp) 1048{ 1049 1050 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X", 1051 bp, bp->b_vp, bp->b_flags); 1052 KASSERT(bp->b_qindex != QUEUE_NONE, 1053 ("bremfreel: buffer %p not on a queue.", bp)); 1054 BUF_ASSERT_XLOCKED(bp); 1055 mtx_assert(bqlock(bp->b_qindex), MA_OWNED); 1056 1057 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 1058#ifdef INVARIANTS 1059 KASSERT(bq_len[bp->b_qindex] >= 1, ("queue %d underflow", 1060 bp->b_qindex)); 1061 bq_len[bp->b_qindex]--; 1062#endif 1063 bp->b_qindex = QUEUE_NONE; 1064 /* 1065 * If this was a delayed bremfree() we only need to remove the buffer 1066 * from the queue and return the stats are already done. 1067 */ 1068 if (bp->b_flags & B_REMFREE) { 1069 bp->b_flags &= ~B_REMFREE; 1070 return; 1071 } 1072 bufcountsub(bp); 1073} 1074 1075/* 1076 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 1077 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 1078 * the buffer is valid and we do not have to do anything. 1079 */ 1080void 1081breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, 1082 int cnt, struct ucred * cred) 1083{ 1084 struct buf *rabp; 1085 int i; 1086 1087 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 1088 if (inmem(vp, *rablkno)) 1089 continue; 1090 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 1091 1092 if ((rabp->b_flags & B_CACHE) == 0) { 1093 if (!TD_IS_IDLETHREAD(curthread)) 1094 curthread->td_ru.ru_inblock++; 1095 rabp->b_flags |= B_ASYNC; 1096 rabp->b_flags &= ~B_INVAL; 1097 rabp->b_ioflags &= ~BIO_ERROR; 1098 rabp->b_iocmd = BIO_READ; 1099 if (rabp->b_rcred == NOCRED && cred != NOCRED) 1100 rabp->b_rcred = crhold(cred); 1101 vfs_busy_pages(rabp, 0); 1102 BUF_KERNPROC(rabp); 1103 rabp->b_iooffset = dbtob(rabp->b_blkno); 1104 bstrategy(rabp); 1105 } else { 1106 brelse(rabp); 1107 } 1108 } 1109} 1110 1111/* 1112 * Entry point for bread() and breadn() via #defines in sys/buf.h. 1113 * 1114 * Get a buffer with the specified data. Look in the cache first. We 1115 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 1116 * is set, the buffer is valid and we do not have to do anything, see 1117 * getblk(). Also starts asynchronous I/O on read-ahead blocks. 1118 */ 1119int 1120breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno, 1121 int *rabsize, int cnt, struct ucred *cred, int flags, struct buf **bpp) 1122{ 1123 struct buf *bp; 1124 int rv = 0, readwait = 0; 1125 1126 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 1127 /* 1128 * Can only return NULL if GB_LOCK_NOWAIT flag is specified. 1129 */ 1130 *bpp = bp = getblk(vp, blkno, size, 0, 0, flags); 1131 if (bp == NULL) 1132 return (EBUSY); 1133 1134 /* if not found in cache, do some I/O */ 1135 if ((bp->b_flags & B_CACHE) == 0) { 1136 if (!TD_IS_IDLETHREAD(curthread)) 1137 curthread->td_ru.ru_inblock++; 1138 bp->b_iocmd = BIO_READ; 1139 bp->b_flags &= ~B_INVAL; 1140 bp->b_ioflags &= ~BIO_ERROR; 1141 if (bp->b_rcred == NOCRED && cred != NOCRED) 1142 bp->b_rcred = crhold(cred); 1143 vfs_busy_pages(bp, 0); 1144 bp->b_iooffset = dbtob(bp->b_blkno); 1145 bstrategy(bp); 1146 ++readwait; 1147 } 1148 1149 breada(vp, rablkno, rabsize, cnt, cred); 1150 1151 if (readwait) { 1152 rv = bufwait(bp); 1153 } 1154 return (rv); 1155} 1156 1157/* 1158 * Write, release buffer on completion. (Done by iodone 1159 * if async). Do not bother writing anything if the buffer 1160 * is invalid. 1161 * 1162 * Note that we set B_CACHE here, indicating that buffer is 1163 * fully valid and thus cacheable. This is true even of NFS 1164 * now so we set it generally. This could be set either here 1165 * or in biodone() since the I/O is synchronous. We put it 1166 * here. 1167 */ 1168int 1169bufwrite(struct buf *bp) 1170{ 1171 int oldflags; 1172 struct vnode *vp; 1173 long space; 1174 int vp_md; 1175 1176 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1177 if (bp->b_flags & B_INVAL) { 1178 brelse(bp); 1179 return (0); 1180 } 1181 1182 if (bp->b_flags & B_BARRIER) 1183 barrierwrites++; 1184 1185 oldflags = bp->b_flags; 1186 1187 BUF_ASSERT_HELD(bp); 1188 1189 if (bp->b_pin_count > 0) 1190 bunpin_wait(bp); 1191 1192 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 1193 ("FFS background buffer should not get here %p", bp)); 1194 1195 vp = bp->b_vp; 1196 if (vp) 1197 vp_md = vp->v_vflag & VV_MD; 1198 else 1199 vp_md = 0; 1200 1201 /* 1202 * Mark the buffer clean. Increment the bufobj write count 1203 * before bundirty() call, to prevent other thread from seeing 1204 * empty dirty list and zero counter for writes in progress, 1205 * falsely indicating that the bufobj is clean. 1206 */ 1207 bufobj_wref(bp->b_bufobj); 1208 bundirty(bp); 1209 1210 bp->b_flags &= ~B_DONE; 1211 bp->b_ioflags &= ~BIO_ERROR; 1212 bp->b_flags |= B_CACHE; 1213 bp->b_iocmd = BIO_WRITE; 1214 1215 vfs_busy_pages(bp, 1); 1216 1217 /* 1218 * Normal bwrites pipeline writes 1219 */ 1220 bp->b_runningbufspace = bp->b_bufsize; 1221 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace); 1222 1223 if (!TD_IS_IDLETHREAD(curthread)) 1224 curthread->td_ru.ru_oublock++; 1225 if (oldflags & B_ASYNC) 1226 BUF_KERNPROC(bp); 1227 bp->b_iooffset = dbtob(bp->b_blkno); 1228 bstrategy(bp); 1229 1230 if ((oldflags & B_ASYNC) == 0) { 1231 int rtval = bufwait(bp); 1232 brelse(bp); 1233 return (rtval); 1234 } else if (space > hirunningspace) { 1235 /* 1236 * don't allow the async write to saturate the I/O 1237 * system. We will not deadlock here because 1238 * we are blocking waiting for I/O that is already in-progress 1239 * to complete. We do not block here if it is the update 1240 * or syncer daemon trying to clean up as that can lead 1241 * to deadlock. 1242 */ 1243 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 1244 waitrunningbufspace(); 1245 } 1246 1247 return (0); 1248} 1249 1250void 1251bufbdflush(struct bufobj *bo, struct buf *bp) 1252{ 1253 struct buf *nbp; 1254 1255 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 1256 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 1257 altbufferflushes++; 1258 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 1259 BO_LOCK(bo); 1260 /* 1261 * Try to find a buffer to flush. 1262 */ 1263 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 1264 if ((nbp->b_vflags & BV_BKGRDINPROG) || 1265 BUF_LOCK(nbp, 1266 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 1267 continue; 1268 if (bp == nbp) 1269 panic("bdwrite: found ourselves"); 1270 BO_UNLOCK(bo); 1271 /* Don't countdeps with the bo lock held. */ 1272 if (buf_countdeps(nbp, 0)) { 1273 BO_LOCK(bo); 1274 BUF_UNLOCK(nbp); 1275 continue; 1276 } 1277 if (nbp->b_flags & B_CLUSTEROK) { 1278 vfs_bio_awrite(nbp); 1279 } else { 1280 bremfree(nbp); 1281 bawrite(nbp); 1282 } 1283 dirtybufferflushes++; 1284 break; 1285 } 1286 if (nbp == NULL) 1287 BO_UNLOCK(bo); 1288 } 1289} 1290 1291/* 1292 * Delayed write. (Buffer is marked dirty). Do not bother writing 1293 * anything if the buffer is marked invalid. 1294 * 1295 * Note that since the buffer must be completely valid, we can safely 1296 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 1297 * biodone() in order to prevent getblk from writing the buffer 1298 * out synchronously. 1299 */ 1300void 1301bdwrite(struct buf *bp) 1302{ 1303 struct thread *td = curthread; 1304 struct vnode *vp; 1305 struct bufobj *bo; 1306 1307 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1308 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1309 KASSERT((bp->b_flags & B_BARRIER) == 0, 1310 ("Barrier request in delayed write %p", bp)); 1311 BUF_ASSERT_HELD(bp); 1312 1313 if (bp->b_flags & B_INVAL) { 1314 brelse(bp); 1315 return; 1316 } 1317 1318 /* 1319 * If we have too many dirty buffers, don't create any more. 1320 * If we are wildly over our limit, then force a complete 1321 * cleanup. Otherwise, just keep the situation from getting 1322 * out of control. Note that we have to avoid a recursive 1323 * disaster and not try to clean up after our own cleanup! 1324 */ 1325 vp = bp->b_vp; 1326 bo = bp->b_bufobj; 1327 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 1328 td->td_pflags |= TDP_INBDFLUSH; 1329 BO_BDFLUSH(bo, bp); 1330 td->td_pflags &= ~TDP_INBDFLUSH; 1331 } else 1332 recursiveflushes++; 1333 1334 bdirty(bp); 1335 /* 1336 * Set B_CACHE, indicating that the buffer is fully valid. This is 1337 * true even of NFS now. 1338 */ 1339 bp->b_flags |= B_CACHE; 1340 1341 /* 1342 * This bmap keeps the system from needing to do the bmap later, 1343 * perhaps when the system is attempting to do a sync. Since it 1344 * is likely that the indirect block -- or whatever other datastructure 1345 * that the filesystem needs is still in memory now, it is a good 1346 * thing to do this. Note also, that if the pageout daemon is 1347 * requesting a sync -- there might not be enough memory to do 1348 * the bmap then... So, this is important to do. 1349 */ 1350 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 1351 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 1352 } 1353 1354 /* 1355 * Set the *dirty* buffer range based upon the VM system dirty 1356 * pages. 1357 * 1358 * Mark the buffer pages as clean. We need to do this here to 1359 * satisfy the vnode_pager and the pageout daemon, so that it 1360 * thinks that the pages have been "cleaned". Note that since 1361 * the pages are in a delayed write buffer -- the VFS layer 1362 * "will" see that the pages get written out on the next sync, 1363 * or perhaps the cluster will be completed. 1364 */ 1365 vfs_clean_pages_dirty_buf(bp); 1366 bqrelse(bp); 1367 1368 /* 1369 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 1370 * due to the softdep code. 1371 */ 1372} 1373 1374/* 1375 * bdirty: 1376 * 1377 * Turn buffer into delayed write request. We must clear BIO_READ and 1378 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 1379 * itself to properly update it in the dirty/clean lists. We mark it 1380 * B_DONE to ensure that any asynchronization of the buffer properly 1381 * clears B_DONE ( else a panic will occur later ). 1382 * 1383 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 1384 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 1385 * should only be called if the buffer is known-good. 1386 * 1387 * Since the buffer is not on a queue, we do not update the numfreebuffers 1388 * count. 1389 * 1390 * The buffer must be on QUEUE_NONE. 1391 */ 1392void 1393bdirty(struct buf *bp) 1394{ 1395 1396 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 1397 bp, bp->b_vp, bp->b_flags); 1398 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1399 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1400 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1401 BUF_ASSERT_HELD(bp); 1402 bp->b_flags &= ~(B_RELBUF); 1403 bp->b_iocmd = BIO_WRITE; 1404 1405 if ((bp->b_flags & B_DELWRI) == 0) { 1406 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 1407 reassignbuf(bp); 1408 bdirtyadd(); 1409 } 1410} 1411 1412/* 1413 * bundirty: 1414 * 1415 * Clear B_DELWRI for buffer. 1416 * 1417 * Since the buffer is not on a queue, we do not update the numfreebuffers 1418 * count. 1419 * 1420 * The buffer must be on QUEUE_NONE. 1421 */ 1422 1423void 1424bundirty(struct buf *bp) 1425{ 1426 1427 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1428 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1429 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1430 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1431 BUF_ASSERT_HELD(bp); 1432 1433 if (bp->b_flags & B_DELWRI) { 1434 bp->b_flags &= ~B_DELWRI; 1435 reassignbuf(bp); 1436 bdirtysub(); 1437 } 1438 /* 1439 * Since it is now being written, we can clear its deferred write flag. 1440 */ 1441 bp->b_flags &= ~B_DEFERRED; 1442} 1443 1444/* 1445 * bawrite: 1446 * 1447 * Asynchronous write. Start output on a buffer, but do not wait for 1448 * it to complete. The buffer is released when the output completes. 1449 * 1450 * bwrite() ( or the VOP routine anyway ) is responsible for handling 1451 * B_INVAL buffers. Not us. 1452 */ 1453void 1454bawrite(struct buf *bp) 1455{ 1456 1457 bp->b_flags |= B_ASYNC; 1458 (void) bwrite(bp); 1459} 1460 1461/* 1462 * babarrierwrite: 1463 * 1464 * Asynchronous barrier write. Start output on a buffer, but do not 1465 * wait for it to complete. Place a write barrier after this write so 1466 * that this buffer and all buffers written before it are committed to 1467 * the disk before any buffers written after this write are committed 1468 * to the disk. The buffer is released when the output completes. 1469 */ 1470void 1471babarrierwrite(struct buf *bp) 1472{ 1473 1474 bp->b_flags |= B_ASYNC | B_BARRIER; 1475 (void) bwrite(bp); 1476} 1477 1478/* 1479 * bbarrierwrite: 1480 * 1481 * Synchronous barrier write. Start output on a buffer and wait for 1482 * it to complete. Place a write barrier after this write so that 1483 * this buffer and all buffers written before it are committed to 1484 * the disk before any buffers written after this write are committed 1485 * to the disk. The buffer is released when the output completes. 1486 */ 1487int 1488bbarrierwrite(struct buf *bp) 1489{ 1490 1491 bp->b_flags |= B_BARRIER; 1492 return (bwrite(bp)); 1493} 1494 1495/* 1496 * bwillwrite: 1497 * 1498 * Called prior to the locking of any vnodes when we are expecting to 1499 * write. We do not want to starve the buffer cache with too many 1500 * dirty buffers so we block here. By blocking prior to the locking 1501 * of any vnodes we attempt to avoid the situation where a locked vnode 1502 * prevents the various system daemons from flushing related buffers. 1503 */ 1504void 1505bwillwrite(void) 1506{ 1507 1508 if (numdirtybuffers >= hidirtybuffers) { 1509 mtx_lock(&bdirtylock); 1510 while (numdirtybuffers >= hidirtybuffers) { 1511 bdirtywait = 1; 1512 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4), 1513 "flswai", 0); 1514 } 1515 mtx_unlock(&bdirtylock); 1516 } 1517} 1518 1519/* 1520 * Return true if we have too many dirty buffers. 1521 */ 1522int 1523buf_dirty_count_severe(void) 1524{ 1525 1526 return(numdirtybuffers >= hidirtybuffers); 1527} 1528 1529static __noinline int 1530buf_vm_page_count_severe(void) 1531{ 1532 1533 KFAIL_POINT_CODE(DEBUG_FP, buf_pressure, return 1); 1534 1535 return vm_page_count_severe(); 1536} 1537 1538/* 1539 * brelse: 1540 * 1541 * Release a busy buffer and, if requested, free its resources. The 1542 * buffer will be stashed in the appropriate bufqueue[] allowing it 1543 * to be accessed later as a cache entity or reused for other purposes. 1544 */ 1545void 1546brelse(struct buf *bp) 1547{ 1548 int qindex; 1549 1550 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 1551 bp, bp->b_vp, bp->b_flags); 1552 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1553 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1554 1555 if (BUF_LOCKRECURSED(bp)) { 1556 /* 1557 * Do not process, in particular, do not handle the 1558 * B_INVAL/B_RELBUF and do not release to free list. 1559 */ 1560 BUF_UNLOCK(bp); 1561 return; 1562 } 1563 1564 if (bp->b_flags & B_MANAGED) { 1565 bqrelse(bp); 1566 return; 1567 } 1568 1569 if ((bp->b_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) { 1570 BO_LOCK(bp->b_bufobj); 1571 bp->b_vflags &= ~BV_BKGRDERR; 1572 BO_UNLOCK(bp->b_bufobj); 1573 bdirty(bp); 1574 } 1575 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 1576 bp->b_error == EIO && !(bp->b_flags & B_INVAL)) { 1577 /* 1578 * Failed write, redirty. Must clear BIO_ERROR to prevent 1579 * pages from being scrapped. If the error is anything 1580 * other than an I/O error (EIO), assume that retrying 1581 * is futile. 1582 */ 1583 bp->b_ioflags &= ~BIO_ERROR; 1584 bdirty(bp); 1585 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 1586 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 1587 /* 1588 * Either a failed I/O or we were asked to free or not 1589 * cache the buffer. 1590 */ 1591 bp->b_flags |= B_INVAL; 1592 if (!LIST_EMPTY(&bp->b_dep)) 1593 buf_deallocate(bp); 1594 if (bp->b_flags & B_DELWRI) 1595 bdirtysub(); 1596 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1597 if ((bp->b_flags & B_VMIO) == 0) { 1598 if (bp->b_bufsize) 1599 allocbuf(bp, 0); 1600 if (bp->b_vp) 1601 brelvp(bp); 1602 } 1603 } 1604 1605 /* 1606 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1607 * is called with B_DELWRI set, the underlying pages may wind up 1608 * getting freed causing a previous write (bdwrite()) to get 'lost' 1609 * because pages associated with a B_DELWRI bp are marked clean. 1610 * 1611 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1612 * if B_DELWRI is set. 1613 * 1614 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1615 * on pages to return pages to the VM page queues. 1616 */ 1617 if (bp->b_flags & B_DELWRI) 1618 bp->b_flags &= ~B_RELBUF; 1619 else if (buf_vm_page_count_severe()) { 1620 /* 1621 * BKGRDINPROG can only be set with the buf and bufobj 1622 * locks both held. We tolerate a race to clear it here. 1623 */ 1624 if (!(bp->b_vflags & BV_BKGRDINPROG)) 1625 bp->b_flags |= B_RELBUF; 1626 } 1627 1628 /* 1629 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1630 * constituted, not even NFS buffers now. Two flags effect this. If 1631 * B_INVAL, the struct buf is invalidated but the VM object is kept 1632 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1633 * 1634 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 1635 * invalidated. BIO_ERROR cannot be set for a failed write unless the 1636 * buffer is also B_INVAL because it hits the re-dirtying code above. 1637 * 1638 * Normally we can do this whether a buffer is B_DELWRI or not. If 1639 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1640 * the commit state and we cannot afford to lose the buffer. If the 1641 * buffer has a background write in progress, we need to keep it 1642 * around to prevent it from being reconstituted and starting a second 1643 * background write. 1644 */ 1645 if ((bp->b_flags & B_VMIO) 1646 && !(bp->b_vp->v_mount != NULL && 1647 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 1648 !vn_isdisk(bp->b_vp, NULL) && 1649 (bp->b_flags & B_DELWRI)) 1650 ) { 1651 1652 int i, j, resid; 1653 vm_page_t m; 1654 off_t foff; 1655 vm_pindex_t poff; 1656 vm_object_t obj; 1657 1658 obj = bp->b_bufobj->bo_object; 1659 1660 /* 1661 * Get the base offset and length of the buffer. Note that 1662 * in the VMIO case if the buffer block size is not 1663 * page-aligned then b_data pointer may not be page-aligned. 1664 * But our b_pages[] array *IS* page aligned. 1665 * 1666 * block sizes less then DEV_BSIZE (usually 512) are not 1667 * supported due to the page granularity bits (m->valid, 1668 * m->dirty, etc...). 1669 * 1670 * See man buf(9) for more information 1671 */ 1672 resid = bp->b_bufsize; 1673 foff = bp->b_offset; 1674 for (i = 0; i < bp->b_npages; i++) { 1675 int had_bogus = 0; 1676 1677 m = bp->b_pages[i]; 1678 1679 /* 1680 * If we hit a bogus page, fixup *all* the bogus pages 1681 * now. 1682 */ 1683 if (m == bogus_page) { 1684 poff = OFF_TO_IDX(bp->b_offset); 1685 had_bogus = 1; 1686 1687 VM_OBJECT_RLOCK(obj); 1688 for (j = i; j < bp->b_npages; j++) { 1689 vm_page_t mtmp; 1690 mtmp = bp->b_pages[j]; 1691 if (mtmp == bogus_page) { 1692 mtmp = vm_page_lookup(obj, poff + j); 1693 if (!mtmp) { 1694 panic("brelse: page missing\n"); 1695 } 1696 bp->b_pages[j] = mtmp; 1697 } 1698 } 1699 VM_OBJECT_RUNLOCK(obj); 1700 1701 if ((bp->b_flags & (B_INVAL | B_UNMAPPED)) == 0) { 1702 BUF_CHECK_MAPPED(bp); 1703 pmap_qenter( 1704 trunc_page((vm_offset_t)bp->b_data), 1705 bp->b_pages, bp->b_npages); 1706 } 1707 m = bp->b_pages[i]; 1708 } 1709 if ((bp->b_flags & B_NOCACHE) || 1710 (bp->b_ioflags & BIO_ERROR && 1711 bp->b_iocmd == BIO_READ)) { 1712 int poffset = foff & PAGE_MASK; 1713 int presid = resid > (PAGE_SIZE - poffset) ? 1714 (PAGE_SIZE - poffset) : resid; 1715 1716 KASSERT(presid >= 0, ("brelse: extra page")); 1717 VM_OBJECT_WLOCK(obj); 1718 while (vm_page_xbusied(m)) { 1719 vm_page_lock(m); 1720 VM_OBJECT_WUNLOCK(obj); 1721 vm_page_busy_sleep(m, "mbncsh"); 1722 VM_OBJECT_WLOCK(obj); 1723 } 1724 if (pmap_page_wired_mappings(m) == 0) 1725 vm_page_set_invalid(m, poffset, presid); 1726 VM_OBJECT_WUNLOCK(obj); 1727 if (had_bogus) 1728 printf("avoided corruption bug in bogus_page/brelse code\n"); 1729 } 1730 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1731 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1732 } 1733 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1734 vfs_vmio_release(bp); 1735 1736 } else if (bp->b_flags & B_VMIO) { 1737 1738 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1739 vfs_vmio_release(bp); 1740 } 1741 1742 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) { 1743 if (bp->b_bufsize != 0) 1744 allocbuf(bp, 0); 1745 if (bp->b_vp != NULL) 1746 brelvp(bp); 1747 } 1748 1749 /* 1750 * If the buffer has junk contents signal it and eventually 1751 * clean up B_DELWRI and diassociate the vnode so that gbincore() 1752 * doesn't find it. 1753 */ 1754 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 1755 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 1756 bp->b_flags |= B_INVAL; 1757 if (bp->b_flags & B_INVAL) { 1758 if (bp->b_flags & B_DELWRI) 1759 bundirty(bp); 1760 if (bp->b_vp) 1761 brelvp(bp); 1762 } 1763 1764 /* buffers with no memory */ 1765 if (bp->b_bufsize == 0) { 1766 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1767 if (bp->b_vflags & BV_BKGRDINPROG) 1768 panic("losing buffer 1"); 1769 if (bp->b_kvasize) 1770 qindex = QUEUE_EMPTYKVA; 1771 else 1772 qindex = QUEUE_EMPTY; 1773 bp->b_flags |= B_AGE; 1774 /* buffers with junk contents */ 1775 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 1776 (bp->b_ioflags & BIO_ERROR)) { 1777 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1778 if (bp->b_vflags & BV_BKGRDINPROG) 1779 panic("losing buffer 2"); 1780 qindex = QUEUE_CLEAN; 1781 bp->b_flags |= B_AGE; 1782 /* remaining buffers */ 1783 } else if (bp->b_flags & B_DELWRI) 1784 qindex = QUEUE_DIRTY; 1785 else 1786 qindex = QUEUE_CLEAN; 1787 1788 binsfree(bp, qindex); 1789 1790 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 1791 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1792 panic("brelse: not dirty"); 1793 /* unlock */ 1794 BUF_UNLOCK(bp); 1795} 1796 1797/* 1798 * Release a buffer back to the appropriate queue but do not try to free 1799 * it. The buffer is expected to be used again soon. 1800 * 1801 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1802 * biodone() to requeue an async I/O on completion. It is also used when 1803 * known good buffers need to be requeued but we think we may need the data 1804 * again soon. 1805 * 1806 * XXX we should be able to leave the B_RELBUF hint set on completion. 1807 */ 1808void 1809bqrelse(struct buf *bp) 1810{ 1811 int qindex; 1812 1813 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1814 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1815 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1816 1817 if (BUF_LOCKRECURSED(bp)) { 1818 /* do not release to free list */ 1819 BUF_UNLOCK(bp); 1820 return; 1821 } 1822 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1823 1824 if (bp->b_flags & B_MANAGED) { 1825 if (bp->b_flags & B_REMFREE) 1826 bremfreef(bp); 1827 goto out; 1828 } 1829 1830 /* buffers with stale but valid contents */ 1831 if ((bp->b_flags & B_DELWRI) != 0 || (bp->b_vflags & (BV_BKGRDINPROG | 1832 BV_BKGRDERR)) == BV_BKGRDERR) { 1833 BO_LOCK(bp->b_bufobj); 1834 bp->b_vflags &= ~BV_BKGRDERR; 1835 BO_UNLOCK(bp->b_bufobj); 1836 qindex = QUEUE_DIRTY; 1837 } else { 1838 if ((bp->b_flags & B_DELWRI) == 0 && 1839 (bp->b_xflags & BX_VNDIRTY)) 1840 panic("bqrelse: not dirty"); 1841 /* 1842 * BKGRDINPROG can only be set with the buf and bufobj 1843 * locks both held. We tolerate a race to clear it here. 1844 */ 1845 if (buf_vm_page_count_severe() && 1846 (bp->b_vflags & BV_BKGRDINPROG) == 0) { 1847 /* 1848 * We are too low on memory, we have to try to free 1849 * the buffer (most importantly: the wired pages 1850 * making up its backing store) *now*. 1851 */ 1852 brelse(bp); 1853 return; 1854 } 1855 qindex = QUEUE_CLEAN; 1856 } 1857 binsfree(bp, qindex); 1858 1859out: 1860 /* unlock */ 1861 BUF_UNLOCK(bp); 1862} 1863 1864/* Give pages used by the bp back to the VM system (where possible) */ 1865static void 1866vfs_vmio_release(struct buf *bp) 1867{ 1868 vm_object_t obj; 1869 vm_page_t m; 1870 int i; 1871 1872 if ((bp->b_flags & B_UNMAPPED) == 0) { 1873 BUF_CHECK_MAPPED(bp); 1874 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages); 1875 } else 1876 BUF_CHECK_UNMAPPED(bp); 1877 obj = bp->b_bufobj->bo_object; 1878 if (obj != NULL) 1879 VM_OBJECT_WLOCK(obj); 1880 for (i = 0; i < bp->b_npages; i++) { 1881 m = bp->b_pages[i]; 1882 bp->b_pages[i] = NULL; 1883 /* 1884 * In order to keep page LRU ordering consistent, put 1885 * everything on the inactive queue. 1886 */ 1887 vm_page_lock(m); 1888 vm_page_unwire(m, 0); 1889 1890 /* 1891 * Might as well free the page if we can and it has 1892 * no valid data. We also free the page if the 1893 * buffer was used for direct I/O 1894 */ 1895 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid) { 1896 if (m->wire_count == 0 && !vm_page_busied(m)) 1897 vm_page_free(m); 1898 } else if (bp->b_flags & B_DIRECT) 1899 vm_page_try_to_free(m); 1900 else if (buf_vm_page_count_severe()) 1901 vm_page_try_to_cache(m); 1902 vm_page_unlock(m); 1903 } 1904 if (obj != NULL) 1905 VM_OBJECT_WUNLOCK(obj); 1906 1907 if (bp->b_bufsize) { 1908 bufspacewakeup(); 1909 bp->b_bufsize = 0; 1910 } 1911 bp->b_npages = 0; 1912 bp->b_flags &= ~B_VMIO; 1913 if (bp->b_vp) 1914 brelvp(bp); 1915} 1916 1917/* 1918 * Check to see if a block at a particular lbn is available for a clustered 1919 * write. 1920 */ 1921static int 1922vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 1923{ 1924 struct buf *bpa; 1925 int match; 1926 1927 match = 0; 1928 1929 /* If the buf isn't in core skip it */ 1930 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 1931 return (0); 1932 1933 /* If the buf is busy we don't want to wait for it */ 1934 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1935 return (0); 1936 1937 /* Only cluster with valid clusterable delayed write buffers */ 1938 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 1939 (B_DELWRI | B_CLUSTEROK)) 1940 goto done; 1941 1942 if (bpa->b_bufsize != size) 1943 goto done; 1944 1945 /* 1946 * Check to see if it is in the expected place on disk and that the 1947 * block has been mapped. 1948 */ 1949 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 1950 match = 1; 1951done: 1952 BUF_UNLOCK(bpa); 1953 return (match); 1954} 1955 1956/* 1957 * vfs_bio_awrite: 1958 * 1959 * Implement clustered async writes for clearing out B_DELWRI buffers. 1960 * This is much better then the old way of writing only one buffer at 1961 * a time. Note that we may not be presented with the buffers in the 1962 * correct order, so we search for the cluster in both directions. 1963 */ 1964int 1965vfs_bio_awrite(struct buf *bp) 1966{ 1967 struct bufobj *bo; 1968 int i; 1969 int j; 1970 daddr_t lblkno = bp->b_lblkno; 1971 struct vnode *vp = bp->b_vp; 1972 int ncl; 1973 int nwritten; 1974 int size; 1975 int maxcl; 1976 int gbflags; 1977 1978 bo = &vp->v_bufobj; 1979 gbflags = (bp->b_flags & B_UNMAPPED) != 0 ? GB_UNMAPPED : 0; 1980 /* 1981 * right now we support clustered writing only to regular files. If 1982 * we find a clusterable block we could be in the middle of a cluster 1983 * rather then at the beginning. 1984 */ 1985 if ((vp->v_type == VREG) && 1986 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1987 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1988 1989 size = vp->v_mount->mnt_stat.f_iosize; 1990 maxcl = MAXPHYS / size; 1991 1992 BO_RLOCK(bo); 1993 for (i = 1; i < maxcl; i++) 1994 if (vfs_bio_clcheck(vp, size, lblkno + i, 1995 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 1996 break; 1997 1998 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 1999 if (vfs_bio_clcheck(vp, size, lblkno - j, 2000 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 2001 break; 2002 BO_RUNLOCK(bo); 2003 --j; 2004 ncl = i + j; 2005 /* 2006 * this is a possible cluster write 2007 */ 2008 if (ncl != 1) { 2009 BUF_UNLOCK(bp); 2010 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl, 2011 gbflags); 2012 return (nwritten); 2013 } 2014 } 2015 bremfree(bp); 2016 bp->b_flags |= B_ASYNC; 2017 /* 2018 * default (old) behavior, writing out only one block 2019 * 2020 * XXX returns b_bufsize instead of b_bcount for nwritten? 2021 */ 2022 nwritten = bp->b_bufsize; 2023 (void) bwrite(bp); 2024 2025 return (nwritten); 2026} 2027 2028static void 2029setbufkva(struct buf *bp, vm_offset_t addr, int maxsize, int gbflags) 2030{ 2031 2032 KASSERT((bp->b_flags & (B_UNMAPPED | B_KVAALLOC)) == 0 && 2033 bp->b_kvasize == 0, ("call bfreekva(%p)", bp)); 2034 if ((gbflags & GB_UNMAPPED) == 0) { 2035 bp->b_kvabase = (caddr_t)addr; 2036 } else if ((gbflags & GB_KVAALLOC) != 0) { 2037 KASSERT((gbflags & GB_UNMAPPED) != 0, 2038 ("GB_KVAALLOC without GB_UNMAPPED")); 2039 bp->b_kvaalloc = (caddr_t)addr; 2040 bp->b_flags |= B_UNMAPPED | B_KVAALLOC; 2041 atomic_add_long(&unmapped_bufspace, bp->b_kvasize); 2042 } 2043 bp->b_kvasize = maxsize; 2044} 2045 2046/* 2047 * Allocate the buffer KVA and set b_kvasize. Also set b_kvabase if 2048 * needed. 2049 */ 2050static int 2051allocbufkva(struct buf *bp, int maxsize, int gbflags) 2052{ 2053 vm_offset_t addr; 2054 2055 bfreekva(bp); 2056 addr = 0; 2057 2058 if (vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr)) { 2059 /* 2060 * Buffer map is too fragmented. Request the caller 2061 * to defragment the map. 2062 */ 2063 atomic_add_int(&bufdefragcnt, 1); 2064 return (1); 2065 } 2066 setbufkva(bp, addr, maxsize, gbflags); 2067 atomic_add_long(&bufspace, bp->b_kvasize); 2068 return (0); 2069} 2070 2071/* 2072 * Ask the bufdaemon for help, or act as bufdaemon itself, when a 2073 * locked vnode is supplied. 2074 */ 2075static void 2076getnewbuf_bufd_help(struct vnode *vp, int gbflags, int slpflag, int slptimeo, 2077 int defrag) 2078{ 2079 struct thread *td; 2080 char *waitmsg; 2081 int error, fl, flags, norunbuf; 2082 2083 mtx_assert(&bqclean, MA_OWNED); 2084 2085 if (defrag) { 2086 flags = VFS_BIO_NEED_BUFSPACE; 2087 waitmsg = "nbufkv"; 2088 } else if (bufspace >= hibufspace) { 2089 waitmsg = "nbufbs"; 2090 flags = VFS_BIO_NEED_BUFSPACE; 2091 } else { 2092 waitmsg = "newbuf"; 2093 flags = VFS_BIO_NEED_ANY; 2094 } 2095 atomic_set_int(&needsbuffer, flags); 2096 mtx_unlock(&bqclean); 2097 2098 bd_speedup(); /* heeeelp */ 2099 if ((gbflags & GB_NOWAIT_BD) != 0) 2100 return; 2101 2102 td = curthread; 2103 rw_wlock(&nblock); 2104 while ((needsbuffer & flags) != 0) { 2105 if (vp != NULL && vp->v_type != VCHR && 2106 (td->td_pflags & TDP_BUFNEED) == 0) { 2107 rw_wunlock(&nblock); 2108 /* 2109 * getblk() is called with a vnode locked, and 2110 * some majority of the dirty buffers may as 2111 * well belong to the vnode. Flushing the 2112 * buffers there would make a progress that 2113 * cannot be achieved by the buf_daemon, that 2114 * cannot lock the vnode. 2115 */ 2116 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) | 2117 (td->td_pflags & TDP_NORUNNINGBUF); 2118 2119 /* 2120 * Play bufdaemon. The getnewbuf() function 2121 * may be called while the thread owns lock 2122 * for another dirty buffer for the same 2123 * vnode, which makes it impossible to use 2124 * VOP_FSYNC() there, due to the buffer lock 2125 * recursion. 2126 */ 2127 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF; 2128 fl = buf_flush(vp, flushbufqtarget); 2129 td->td_pflags &= norunbuf; 2130 rw_wlock(&nblock); 2131 if (fl != 0) 2132 continue; 2133 if ((needsbuffer & flags) == 0) 2134 break; 2135 } 2136 error = rw_sleep(__DEVOLATILE(void *, &needsbuffer), &nblock, 2137 (PRIBIO + 4) | slpflag, waitmsg, slptimeo); 2138 if (error != 0) 2139 break; 2140 } 2141 rw_wunlock(&nblock); 2142} 2143 2144static void 2145getnewbuf_reuse_bp(struct buf *bp, int qindex) 2146{ 2147 2148 CTR6(KTR_BUF, "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d " 2149 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags, 2150 bp->b_kvasize, bp->b_bufsize, qindex); 2151 mtx_assert(&bqclean, MA_NOTOWNED); 2152 2153 /* 2154 * Note: we no longer distinguish between VMIO and non-VMIO 2155 * buffers. 2156 */ 2157 KASSERT((bp->b_flags & B_DELWRI) == 0, 2158 ("delwri buffer %p found in queue %d", bp, qindex)); 2159 2160 if (qindex == QUEUE_CLEAN) { 2161 if (bp->b_flags & B_VMIO) { 2162 bp->b_flags &= ~B_ASYNC; 2163 vfs_vmio_release(bp); 2164 } 2165 if (bp->b_vp != NULL) 2166 brelvp(bp); 2167 } 2168 2169 /* 2170 * Get the rest of the buffer freed up. b_kva* is still valid 2171 * after this operation. 2172 */ 2173 2174 if (bp->b_rcred != NOCRED) { 2175 crfree(bp->b_rcred); 2176 bp->b_rcred = NOCRED; 2177 } 2178 if (bp->b_wcred != NOCRED) { 2179 crfree(bp->b_wcred); 2180 bp->b_wcred = NOCRED; 2181 } 2182 if (!LIST_EMPTY(&bp->b_dep)) 2183 buf_deallocate(bp); 2184 if (bp->b_vflags & BV_BKGRDINPROG) 2185 panic("losing buffer 3"); 2186 KASSERT(bp->b_vp == NULL, ("bp: %p still has vnode %p. qindex: %d", 2187 bp, bp->b_vp, qindex)); 2188 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 2189 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags)); 2190 2191 if (bp->b_bufsize) 2192 allocbuf(bp, 0); 2193 2194 bp->b_flags &= B_UNMAPPED | B_KVAALLOC; 2195 bp->b_ioflags = 0; 2196 bp->b_xflags = 0; 2197 KASSERT((bp->b_flags & B_INFREECNT) == 0, 2198 ("buf %p still counted as free?", bp)); 2199 bp->b_vflags = 0; 2200 bp->b_vp = NULL; 2201 bp->b_blkno = bp->b_lblkno = 0; 2202 bp->b_offset = NOOFFSET; 2203 bp->b_iodone = 0; 2204 bp->b_error = 0; 2205 bp->b_resid = 0; 2206 bp->b_bcount = 0; 2207 bp->b_npages = 0; 2208 bp->b_dirtyoff = bp->b_dirtyend = 0; 2209 bp->b_bufobj = NULL; 2210 bp->b_pin_count = 0; 2211 bp->b_fsprivate1 = NULL; 2212 bp->b_fsprivate2 = NULL; 2213 bp->b_fsprivate3 = NULL; 2214 2215 LIST_INIT(&bp->b_dep); 2216} 2217 2218static int flushingbufs; 2219 2220static struct buf * 2221getnewbuf_scan(int maxsize, int defrag, int unmapped, int metadata) 2222{ 2223 struct buf *bp, *nbp; 2224 int nqindex, qindex, pass; 2225 2226 KASSERT(!unmapped || !defrag, ("both unmapped and defrag")); 2227 2228 pass = 1; 2229restart: 2230 atomic_add_int(&getnewbufrestarts, 1); 2231 2232 /* 2233 * Setup for scan. If we do not have enough free buffers, 2234 * we setup a degenerate case that immediately fails. Note 2235 * that if we are specially marked process, we are allowed to 2236 * dip into our reserves. 2237 * 2238 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 2239 * for the allocation of the mapped buffer. For unmapped, the 2240 * easiest is to start with EMPTY outright. 2241 * 2242 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 2243 * However, there are a number of cases (defragging, reusing, ...) 2244 * where we cannot backup. 2245 */ 2246 nbp = NULL; 2247 mtx_lock(&bqclean); 2248 if (!defrag && unmapped) { 2249 nqindex = QUEUE_EMPTY; 2250 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 2251 } 2252 if (nbp == NULL) { 2253 nqindex = QUEUE_EMPTYKVA; 2254 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 2255 } 2256 2257 /* 2258 * If no EMPTYKVA buffers and we are either defragging or 2259 * reusing, locate a CLEAN buffer to free or reuse. If 2260 * bufspace useage is low skip this step so we can allocate a 2261 * new buffer. 2262 */ 2263 if (nbp == NULL && (defrag || bufspace >= lobufspace)) { 2264 nqindex = QUEUE_CLEAN; 2265 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2266 } 2267 2268 /* 2269 * If we could not find or were not allowed to reuse a CLEAN 2270 * buffer, check to see if it is ok to use an EMPTY buffer. 2271 * We can only use an EMPTY buffer if allocating its KVA would 2272 * not otherwise run us out of buffer space. No KVA is needed 2273 * for the unmapped allocation. 2274 */ 2275 if (nbp == NULL && defrag == 0 && (bufspace + maxsize < hibufspace || 2276 metadata)) { 2277 nqindex = QUEUE_EMPTY; 2278 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 2279 } 2280 2281 /* 2282 * All available buffers might be clean, retry ignoring the 2283 * lobufspace as the last resort. 2284 */ 2285 if (nbp == NULL && !TAILQ_EMPTY(&bufqueues[QUEUE_CLEAN])) { 2286 nqindex = QUEUE_CLEAN; 2287 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2288 } 2289 2290 /* 2291 * Run scan, possibly freeing data and/or kva mappings on the fly 2292 * depending. 2293 */ 2294 while ((bp = nbp) != NULL) { 2295 qindex = nqindex; 2296 2297 /* 2298 * Calculate next bp (we can only use it if we do not 2299 * block or do other fancy things). 2300 */ 2301 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 2302 switch (qindex) { 2303 case QUEUE_EMPTY: 2304 nqindex = QUEUE_EMPTYKVA; 2305 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 2306 if (nbp != NULL) 2307 break; 2308 /* FALLTHROUGH */ 2309 case QUEUE_EMPTYKVA: 2310 nqindex = QUEUE_CLEAN; 2311 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2312 if (nbp != NULL) 2313 break; 2314 /* FALLTHROUGH */ 2315 case QUEUE_CLEAN: 2316 if (metadata && pass == 1) { 2317 pass = 2; 2318 nqindex = QUEUE_EMPTY; 2319 nbp = TAILQ_FIRST( 2320 &bufqueues[QUEUE_EMPTY]); 2321 } 2322 /* 2323 * nbp is NULL. 2324 */ 2325 break; 2326 } 2327 } 2328 /* 2329 * If we are defragging then we need a buffer with 2330 * b_kvasize != 0. XXX this situation should no longer 2331 * occur, if defrag is non-zero the buffer's b_kvasize 2332 * should also be non-zero at this point. XXX 2333 */ 2334 if (defrag && bp->b_kvasize == 0) { 2335 printf("Warning: defrag empty buffer %p\n", bp); 2336 continue; 2337 } 2338 2339 /* 2340 * Start freeing the bp. This is somewhat involved. nbp 2341 * remains valid only for QUEUE_EMPTY[KVA] bp's. 2342 */ 2343 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2344 continue; 2345 /* 2346 * BKGRDINPROG can only be set with the buf and bufobj 2347 * locks both held. We tolerate a race to clear it here. 2348 */ 2349 if (bp->b_vflags & BV_BKGRDINPROG) { 2350 BUF_UNLOCK(bp); 2351 continue; 2352 } 2353 2354 /* 2355 * Requeue the background write buffer with error. 2356 */ 2357 if ((bp->b_vflags & BV_BKGRDERR) != 0) { 2358 bremfreel(bp); 2359 mtx_unlock(&bqclean); 2360 bqrelse(bp); 2361 continue; 2362 } 2363 2364 KASSERT(bp->b_qindex == qindex, 2365 ("getnewbuf: inconsistent queue %d bp %p", qindex, bp)); 2366 2367 bremfreel(bp); 2368 mtx_unlock(&bqclean); 2369 /* 2370 * NOTE: nbp is now entirely invalid. We can only restart 2371 * the scan from this point on. 2372 */ 2373 2374 getnewbuf_reuse_bp(bp, qindex); 2375 mtx_assert(&bqclean, MA_NOTOWNED); 2376 2377 /* 2378 * If we are defragging then free the buffer. 2379 */ 2380 if (defrag) { 2381 bp->b_flags |= B_INVAL; 2382 bfreekva(bp); 2383 brelse(bp); 2384 defrag = 0; 2385 goto restart; 2386 } 2387 2388 /* 2389 * Notify any waiters for the buffer lock about 2390 * identity change by freeing the buffer. 2391 */ 2392 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp)) { 2393 bp->b_flags |= B_INVAL; 2394 bfreekva(bp); 2395 brelse(bp); 2396 goto restart; 2397 } 2398 2399 if (metadata) 2400 break; 2401 2402 /* 2403 * If we are overcomitted then recover the buffer and its 2404 * KVM space. This occurs in rare situations when multiple 2405 * processes are blocked in getnewbuf() or allocbuf(). 2406 */ 2407 if (bufspace >= hibufspace) 2408 flushingbufs = 1; 2409 if (flushingbufs && bp->b_kvasize != 0) { 2410 bp->b_flags |= B_INVAL; 2411 bfreekva(bp); 2412 brelse(bp); 2413 goto restart; 2414 } 2415 if (bufspace < lobufspace) 2416 flushingbufs = 0; 2417 break; 2418 } 2419 return (bp); 2420} 2421 2422/* 2423 * getnewbuf: 2424 * 2425 * Find and initialize a new buffer header, freeing up existing buffers 2426 * in the bufqueues as necessary. The new buffer is returned locked. 2427 * 2428 * Important: B_INVAL is not set. If the caller wishes to throw the 2429 * buffer away, the caller must set B_INVAL prior to calling brelse(). 2430 * 2431 * We block if: 2432 * We have insufficient buffer headers 2433 * We have insufficient buffer space 2434 * buffer_arena is too fragmented ( space reservation fails ) 2435 * If we have to flush dirty buffers ( but we try to avoid this ) 2436 */ 2437static struct buf * 2438getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int size, int maxsize, 2439 int gbflags) 2440{ 2441 struct buf *bp; 2442 int defrag, metadata; 2443 2444 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 2445 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 2446 if (!unmapped_buf_allowed) 2447 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC); 2448 2449 defrag = 0; 2450 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 || 2451 vp->v_type == VCHR) 2452 metadata = 1; 2453 else 2454 metadata = 0; 2455 /* 2456 * We can't afford to block since we might be holding a vnode lock, 2457 * which may prevent system daemons from running. We deal with 2458 * low-memory situations by proactively returning memory and running 2459 * async I/O rather then sync I/O. 2460 */ 2461 atomic_add_int(&getnewbufcalls, 1); 2462 atomic_subtract_int(&getnewbufrestarts, 1); 2463restart: 2464 bp = getnewbuf_scan(maxsize, defrag, (gbflags & (GB_UNMAPPED | 2465 GB_KVAALLOC)) == GB_UNMAPPED, metadata); 2466 if (bp != NULL) 2467 defrag = 0; 2468 2469 /* 2470 * If we exhausted our list, sleep as appropriate. We may have to 2471 * wakeup various daemons and write out some dirty buffers. 2472 * 2473 * Generally we are sleeping due to insufficient buffer space. 2474 */ 2475 if (bp == NULL) { 2476 mtx_assert(&bqclean, MA_OWNED); 2477 getnewbuf_bufd_help(vp, gbflags, slpflag, slptimeo, defrag); 2478 mtx_assert(&bqclean, MA_NOTOWNED); 2479 } else if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == GB_UNMAPPED) { 2480 mtx_assert(&bqclean, MA_NOTOWNED); 2481 2482 bfreekva(bp); 2483 bp->b_flags |= B_UNMAPPED; 2484 bp->b_kvabase = bp->b_data = unmapped_buf; 2485 bp->b_kvasize = maxsize; 2486 atomic_add_long(&bufspace, bp->b_kvasize); 2487 atomic_add_long(&unmapped_bufspace, bp->b_kvasize); 2488 atomic_add_int(&bufreusecnt, 1); 2489 } else { 2490 mtx_assert(&bqclean, MA_NOTOWNED); 2491 2492 /* 2493 * We finally have a valid bp. We aren't quite out of the 2494 * woods, we still have to reserve kva space. In order 2495 * to keep fragmentation sane we only allocate kva in 2496 * BKVASIZE chunks. 2497 */ 2498 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2499 2500 if (maxsize != bp->b_kvasize || (bp->b_flags & (B_UNMAPPED | 2501 B_KVAALLOC)) == B_UNMAPPED) { 2502 if (allocbufkva(bp, maxsize, gbflags)) { 2503 defrag = 1; 2504 bp->b_flags |= B_INVAL; 2505 brelse(bp); 2506 goto restart; 2507 } 2508 atomic_add_int(&bufreusecnt, 1); 2509 } else if ((bp->b_flags & B_KVAALLOC) != 0 && 2510 (gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == 0) { 2511 /* 2512 * If the reused buffer has KVA allocated, 2513 * reassign b_kvaalloc to b_kvabase. 2514 */ 2515 bp->b_kvabase = bp->b_kvaalloc; 2516 bp->b_flags &= ~B_KVAALLOC; 2517 atomic_subtract_long(&unmapped_bufspace, 2518 bp->b_kvasize); 2519 atomic_add_int(&bufreusecnt, 1); 2520 } else if ((bp->b_flags & (B_UNMAPPED | B_KVAALLOC)) == 0 && 2521 (gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == (GB_UNMAPPED | 2522 GB_KVAALLOC)) { 2523 /* 2524 * The case of reused buffer already have KVA 2525 * mapped, but the request is for unmapped 2526 * buffer with KVA allocated. 2527 */ 2528 bp->b_kvaalloc = bp->b_kvabase; 2529 bp->b_data = bp->b_kvabase = unmapped_buf; 2530 bp->b_flags |= B_UNMAPPED | B_KVAALLOC; 2531 atomic_add_long(&unmapped_bufspace, 2532 bp->b_kvasize); 2533 atomic_add_int(&bufreusecnt, 1); 2534 } 2535 if ((gbflags & GB_UNMAPPED) == 0) { 2536 bp->b_saveaddr = bp->b_kvabase; 2537 bp->b_data = bp->b_saveaddr; 2538 bp->b_flags &= ~B_UNMAPPED; 2539 BUF_CHECK_MAPPED(bp); 2540 } 2541 } 2542 return (bp); 2543} 2544 2545/* 2546 * buf_daemon: 2547 * 2548 * buffer flushing daemon. Buffers are normally flushed by the 2549 * update daemon but if it cannot keep up this process starts to 2550 * take the load in an attempt to prevent getnewbuf() from blocking. 2551 */ 2552 2553static struct kproc_desc buf_kp = { 2554 "bufdaemon", 2555 buf_daemon, 2556 &bufdaemonproc 2557}; 2558SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 2559 2560static int 2561buf_flush(struct vnode *vp, int target) 2562{ 2563 int flushed; 2564 2565 flushed = flushbufqueues(vp, target, 0); 2566 if (flushed == 0) { 2567 /* 2568 * Could not find any buffers without rollback 2569 * dependencies, so just write the first one 2570 * in the hopes of eventually making progress. 2571 */ 2572 if (vp != NULL && target > 2) 2573 target /= 2; 2574 flushbufqueues(vp, target, 1); 2575 } 2576 return (flushed); 2577} 2578 2579static void 2580buf_daemon() 2581{ 2582 int lodirty; 2583 2584 /* 2585 * This process needs to be suspended prior to shutdown sync. 2586 */ 2587 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2588 SHUTDOWN_PRI_LAST); 2589 2590 /* 2591 * This process is allowed to take the buffer cache to the limit 2592 */ 2593 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 2594 mtx_lock(&bdlock); 2595 for (;;) { 2596 bd_request = 0; 2597 mtx_unlock(&bdlock); 2598 2599 kproc_suspend_check(bufdaemonproc); 2600 lodirty = lodirtybuffers; 2601 if (bd_speedupreq) { 2602 lodirty = numdirtybuffers / 2; 2603 bd_speedupreq = 0; 2604 } 2605 /* 2606 * Do the flush. Limit the amount of in-transit I/O we 2607 * allow to build up, otherwise we would completely saturate 2608 * the I/O system. 2609 */ 2610 while (numdirtybuffers > lodirty) { 2611 if (buf_flush(NULL, numdirtybuffers - lodirty) == 0) 2612 break; 2613 kern_yield(PRI_USER); 2614 } 2615 2616 /* 2617 * Only clear bd_request if we have reached our low water 2618 * mark. The buf_daemon normally waits 1 second and 2619 * then incrementally flushes any dirty buffers that have 2620 * built up, within reason. 2621 * 2622 * If we were unable to hit our low water mark and couldn't 2623 * find any flushable buffers, we sleep for a short period 2624 * to avoid endless loops on unlockable buffers. 2625 */ 2626 mtx_lock(&bdlock); 2627 if (numdirtybuffers <= lodirtybuffers) { 2628 /* 2629 * We reached our low water mark, reset the 2630 * request and sleep until we are needed again. 2631 * The sleep is just so the suspend code works. 2632 */ 2633 bd_request = 0; 2634 /* 2635 * Do an extra wakeup in case dirty threshold 2636 * changed via sysctl and the explicit transition 2637 * out of shortfall was missed. 2638 */ 2639 bdirtywakeup(); 2640 if (runningbufspace <= lorunningspace) 2641 runningwakeup(); 2642 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 2643 } else { 2644 /* 2645 * We couldn't find any flushable dirty buffers but 2646 * still have too many dirty buffers, we 2647 * have to sleep and try again. (rare) 2648 */ 2649 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 2650 } 2651 } 2652} 2653 2654/* 2655 * flushbufqueues: 2656 * 2657 * Try to flush a buffer in the dirty queue. We must be careful to 2658 * free up B_INVAL buffers instead of write them, which NFS is 2659 * particularly sensitive to. 2660 */ 2661static int flushwithdeps = 0; 2662SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 2663 0, "Number of buffers flushed with dependecies that require rollbacks"); 2664 2665static int 2666flushbufqueues(struct vnode *lvp, int target, int flushdeps) 2667{ 2668 struct buf *sentinel; 2669 struct vnode *vp; 2670 struct mount *mp; 2671 struct buf *bp; 2672 int hasdeps; 2673 int flushed; 2674 int queue; 2675 int error; 2676 bool unlock; 2677 2678 flushed = 0; 2679 queue = QUEUE_DIRTY; 2680 bp = NULL; 2681 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 2682 sentinel->b_qindex = QUEUE_SENTINEL; 2683 mtx_lock(&bqdirty); 2684 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist); 2685 mtx_unlock(&bqdirty); 2686 while (flushed != target) { 2687 maybe_yield(); 2688 mtx_lock(&bqdirty); 2689 bp = TAILQ_NEXT(sentinel, b_freelist); 2690 if (bp != NULL) { 2691 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2692 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel, 2693 b_freelist); 2694 } else { 2695 mtx_unlock(&bqdirty); 2696 break; 2697 } 2698 /* 2699 * Skip sentinels inserted by other invocations of the 2700 * flushbufqueues(), taking care to not reorder them. 2701 * 2702 * Only flush the buffers that belong to the 2703 * vnode locked by the curthread. 2704 */ 2705 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL && 2706 bp->b_vp != lvp)) { 2707 mtx_unlock(&bqdirty); 2708 continue; 2709 } 2710 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL); 2711 mtx_unlock(&bqdirty); 2712 if (error != 0) 2713 continue; 2714 if (bp->b_pin_count > 0) { 2715 BUF_UNLOCK(bp); 2716 continue; 2717 } 2718 /* 2719 * BKGRDINPROG can only be set with the buf and bufobj 2720 * locks both held. We tolerate a race to clear it here. 2721 */ 2722 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 2723 (bp->b_flags & B_DELWRI) == 0) { 2724 BUF_UNLOCK(bp); 2725 continue; 2726 } 2727 if (bp->b_flags & B_INVAL) { 2728 bremfreef(bp); 2729 brelse(bp); 2730 flushed++; 2731 continue; 2732 } 2733 2734 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 2735 if (flushdeps == 0) { 2736 BUF_UNLOCK(bp); 2737 continue; 2738 } 2739 hasdeps = 1; 2740 } else 2741 hasdeps = 0; 2742 /* 2743 * We must hold the lock on a vnode before writing 2744 * one of its buffers. Otherwise we may confuse, or 2745 * in the case of a snapshot vnode, deadlock the 2746 * system. 2747 * 2748 * The lock order here is the reverse of the normal 2749 * of vnode followed by buf lock. This is ok because 2750 * the NOWAIT will prevent deadlock. 2751 */ 2752 vp = bp->b_vp; 2753 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 2754 BUF_UNLOCK(bp); 2755 continue; 2756 } 2757 if (lvp == NULL) { 2758 unlock = true; 2759 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT); 2760 } else { 2761 ASSERT_VOP_LOCKED(vp, "getbuf"); 2762 unlock = false; 2763 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 : 2764 vn_lock(vp, LK_TRYUPGRADE); 2765 } 2766 if (error == 0) { 2767 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 2768 bp, bp->b_vp, bp->b_flags); 2769 if (curproc == bufdaemonproc) { 2770 vfs_bio_awrite(bp); 2771 } else { 2772 bremfree(bp); 2773 bwrite(bp); 2774 notbufdflushes++; 2775 } 2776 vn_finished_write(mp); 2777 if (unlock) 2778 VOP_UNLOCK(vp, 0); 2779 flushwithdeps += hasdeps; 2780 flushed++; 2781 2782 /* 2783 * Sleeping on runningbufspace while holding 2784 * vnode lock leads to deadlock. 2785 */ 2786 if (curproc == bufdaemonproc && 2787 runningbufspace > hirunningspace) 2788 waitrunningbufspace(); 2789 continue; 2790 } 2791 vn_finished_write(mp); 2792 BUF_UNLOCK(bp); 2793 } 2794 mtx_lock(&bqdirty); 2795 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2796 mtx_unlock(&bqdirty); 2797 free(sentinel, M_TEMP); 2798 return (flushed); 2799} 2800 2801/* 2802 * Check to see if a block is currently memory resident. 2803 */ 2804struct buf * 2805incore(struct bufobj *bo, daddr_t blkno) 2806{ 2807 struct buf *bp; 2808 2809 BO_RLOCK(bo); 2810 bp = gbincore(bo, blkno); 2811 BO_RUNLOCK(bo); 2812 return (bp); 2813} 2814 2815/* 2816 * Returns true if no I/O is needed to access the 2817 * associated VM object. This is like incore except 2818 * it also hunts around in the VM system for the data. 2819 */ 2820 2821static int 2822inmem(struct vnode * vp, daddr_t blkno) 2823{ 2824 vm_object_t obj; 2825 vm_offset_t toff, tinc, size; 2826 vm_page_t m; 2827 vm_ooffset_t off; 2828 2829 ASSERT_VOP_LOCKED(vp, "inmem"); 2830 2831 if (incore(&vp->v_bufobj, blkno)) 2832 return 1; 2833 if (vp->v_mount == NULL) 2834 return 0; 2835 obj = vp->v_object; 2836 if (obj == NULL) 2837 return (0); 2838 2839 size = PAGE_SIZE; 2840 if (size > vp->v_mount->mnt_stat.f_iosize) 2841 size = vp->v_mount->mnt_stat.f_iosize; 2842 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2843 2844 VM_OBJECT_RLOCK(obj); 2845 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2846 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2847 if (!m) 2848 goto notinmem; 2849 tinc = size; 2850 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2851 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2852 if (vm_page_is_valid(m, 2853 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2854 goto notinmem; 2855 } 2856 VM_OBJECT_RUNLOCK(obj); 2857 return 1; 2858 2859notinmem: 2860 VM_OBJECT_RUNLOCK(obj); 2861 return (0); 2862} 2863 2864/* 2865 * Set the dirty range for a buffer based on the status of the dirty 2866 * bits in the pages comprising the buffer. The range is limited 2867 * to the size of the buffer. 2868 * 2869 * Tell the VM system that the pages associated with this buffer 2870 * are clean. This is used for delayed writes where the data is 2871 * going to go to disk eventually without additional VM intevention. 2872 * 2873 * Note that while we only really need to clean through to b_bcount, we 2874 * just go ahead and clean through to b_bufsize. 2875 */ 2876static void 2877vfs_clean_pages_dirty_buf(struct buf *bp) 2878{ 2879 vm_ooffset_t foff, noff, eoff; 2880 vm_page_t m; 2881 int i; 2882 2883 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 2884 return; 2885 2886 foff = bp->b_offset; 2887 KASSERT(bp->b_offset != NOOFFSET, 2888 ("vfs_clean_pages_dirty_buf: no buffer offset")); 2889 2890 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 2891 vfs_drain_busy_pages(bp); 2892 vfs_setdirty_locked_object(bp); 2893 for (i = 0; i < bp->b_npages; i++) { 2894 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2895 eoff = noff; 2896 if (eoff > bp->b_offset + bp->b_bufsize) 2897 eoff = bp->b_offset + bp->b_bufsize; 2898 m = bp->b_pages[i]; 2899 vfs_page_set_validclean(bp, foff, m); 2900 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 2901 foff = noff; 2902 } 2903 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 2904} 2905 2906static void 2907vfs_setdirty_locked_object(struct buf *bp) 2908{ 2909 vm_object_t object; 2910 int i; 2911 2912 object = bp->b_bufobj->bo_object; 2913 VM_OBJECT_ASSERT_WLOCKED(object); 2914 2915 /* 2916 * We qualify the scan for modified pages on whether the 2917 * object has been flushed yet. 2918 */ 2919 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) { 2920 vm_offset_t boffset; 2921 vm_offset_t eoffset; 2922 2923 /* 2924 * test the pages to see if they have been modified directly 2925 * by users through the VM system. 2926 */ 2927 for (i = 0; i < bp->b_npages; i++) 2928 vm_page_test_dirty(bp->b_pages[i]); 2929 2930 /* 2931 * Calculate the encompassing dirty range, boffset and eoffset, 2932 * (eoffset - boffset) bytes. 2933 */ 2934 2935 for (i = 0; i < bp->b_npages; i++) { 2936 if (bp->b_pages[i]->dirty) 2937 break; 2938 } 2939 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2940 2941 for (i = bp->b_npages - 1; i >= 0; --i) { 2942 if (bp->b_pages[i]->dirty) { 2943 break; 2944 } 2945 } 2946 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2947 2948 /* 2949 * Fit it to the buffer. 2950 */ 2951 2952 if (eoffset > bp->b_bcount) 2953 eoffset = bp->b_bcount; 2954 2955 /* 2956 * If we have a good dirty range, merge with the existing 2957 * dirty range. 2958 */ 2959 2960 if (boffset < eoffset) { 2961 if (bp->b_dirtyoff > boffset) 2962 bp->b_dirtyoff = boffset; 2963 if (bp->b_dirtyend < eoffset) 2964 bp->b_dirtyend = eoffset; 2965 } 2966 } 2967} 2968 2969/* 2970 * Allocate the KVA mapping for an existing buffer. It handles the 2971 * cases of both B_UNMAPPED buffer, and buffer with the preallocated 2972 * KVA which is not mapped (B_KVAALLOC). 2973 */ 2974static void 2975bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags) 2976{ 2977 struct buf *scratch_bp; 2978 int bsize, maxsize, need_mapping, need_kva; 2979 off_t offset; 2980 2981 need_mapping = (bp->b_flags & B_UNMAPPED) != 0 && 2982 (gbflags & GB_UNMAPPED) == 0; 2983 need_kva = (bp->b_flags & (B_KVAALLOC | B_UNMAPPED)) == B_UNMAPPED && 2984 (gbflags & GB_KVAALLOC) != 0; 2985 if (!need_mapping && !need_kva) 2986 return; 2987 2988 BUF_CHECK_UNMAPPED(bp); 2989 2990 if (need_mapping && (bp->b_flags & B_KVAALLOC) != 0) { 2991 /* 2992 * Buffer is not mapped, but the KVA was already 2993 * reserved at the time of the instantiation. Use the 2994 * allocated space. 2995 */ 2996 bp->b_flags &= ~B_KVAALLOC; 2997 KASSERT(bp->b_kvaalloc != 0, ("kvaalloc == 0")); 2998 bp->b_kvabase = bp->b_kvaalloc; 2999 atomic_subtract_long(&unmapped_bufspace, bp->b_kvasize); 3000 goto has_addr; 3001 } 3002 3003 /* 3004 * Calculate the amount of the address space we would reserve 3005 * if the buffer was mapped. 3006 */ 3007 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize; 3008 offset = blkno * bsize; 3009 maxsize = size + (offset & PAGE_MASK); 3010 maxsize = imax(maxsize, bsize); 3011 3012mapping_loop: 3013 if (allocbufkva(bp, maxsize, gbflags)) { 3014 /* 3015 * Request defragmentation. getnewbuf() returns us the 3016 * allocated space by the scratch buffer KVA. 3017 */ 3018 scratch_bp = getnewbuf(bp->b_vp, 0, 0, size, maxsize, gbflags | 3019 (GB_UNMAPPED | GB_KVAALLOC)); 3020 if (scratch_bp == NULL) { 3021 if ((gbflags & GB_NOWAIT_BD) != 0) { 3022 /* 3023 * XXXKIB: defragmentation cannot 3024 * succeed, not sure what else to do. 3025 */ 3026 panic("GB_NOWAIT_BD and B_UNMAPPED %p", bp); 3027 } 3028 atomic_add_int(&mappingrestarts, 1); 3029 goto mapping_loop; 3030 } 3031 KASSERT((scratch_bp->b_flags & B_KVAALLOC) != 0, 3032 ("scratch bp !B_KVAALLOC %p", scratch_bp)); 3033 setbufkva(bp, (vm_offset_t)scratch_bp->b_kvaalloc, 3034 scratch_bp->b_kvasize, gbflags); 3035 3036 /* Get rid of the scratch buffer. */ 3037 scratch_bp->b_kvasize = 0; 3038 scratch_bp->b_flags |= B_INVAL; 3039 scratch_bp->b_flags &= ~(B_UNMAPPED | B_KVAALLOC); 3040 brelse(scratch_bp); 3041 } 3042 if (!need_mapping) 3043 return; 3044 3045has_addr: 3046 bp->b_saveaddr = bp->b_kvabase; 3047 bp->b_data = bp->b_saveaddr; /* b_offset is handled by bpmap_qenter */ 3048 bp->b_flags &= ~B_UNMAPPED; 3049 BUF_CHECK_MAPPED(bp); 3050 bpmap_qenter(bp); 3051} 3052 3053/* 3054 * getblk: 3055 * 3056 * Get a block given a specified block and offset into a file/device. 3057 * The buffers B_DONE bit will be cleared on return, making it almost 3058 * ready for an I/O initiation. B_INVAL may or may not be set on 3059 * return. The caller should clear B_INVAL prior to initiating a 3060 * READ. 3061 * 3062 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 3063 * an existing buffer. 3064 * 3065 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 3066 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 3067 * and then cleared based on the backing VM. If the previous buffer is 3068 * non-0-sized but invalid, B_CACHE will be cleared. 3069 * 3070 * If getblk() must create a new buffer, the new buffer is returned with 3071 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 3072 * case it is returned with B_INVAL clear and B_CACHE set based on the 3073 * backing VM. 3074 * 3075 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 3076 * B_CACHE bit is clear. 3077 * 3078 * What this means, basically, is that the caller should use B_CACHE to 3079 * determine whether the buffer is fully valid or not and should clear 3080 * B_INVAL prior to issuing a read. If the caller intends to validate 3081 * the buffer by loading its data area with something, the caller needs 3082 * to clear B_INVAL. If the caller does this without issuing an I/O, 3083 * the caller should set B_CACHE ( as an optimization ), else the caller 3084 * should issue the I/O and biodone() will set B_CACHE if the I/O was 3085 * a write attempt or if it was a successfull read. If the caller 3086 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 3087 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 3088 */ 3089struct buf * 3090getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3091 int flags) 3092{ 3093 struct buf *bp; 3094 struct bufobj *bo; 3095 int bsize, error, maxsize, vmio; 3096 off_t offset; 3097 3098 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 3099 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3100 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3101 ASSERT_VOP_LOCKED(vp, "getblk"); 3102 if (size > MAXBCACHEBUF) 3103 panic("getblk: size(%d) > MAXBCACHEBUF(%d)\n", size, 3104 MAXBCACHEBUF); 3105 if (!unmapped_buf_allowed) 3106 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3107 3108 bo = &vp->v_bufobj; 3109loop: 3110 BO_RLOCK(bo); 3111 bp = gbincore(bo, blkno); 3112 if (bp != NULL) { 3113 int lockflags; 3114 /* 3115 * Buffer is in-core. If the buffer is not busy nor managed, 3116 * it must be on a queue. 3117 */ 3118 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 3119 3120 if (flags & GB_LOCK_NOWAIT) 3121 lockflags |= LK_NOWAIT; 3122 3123 error = BUF_TIMELOCK(bp, lockflags, 3124 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo); 3125 3126 /* 3127 * If we slept and got the lock we have to restart in case 3128 * the buffer changed identities. 3129 */ 3130 if (error == ENOLCK) 3131 goto loop; 3132 /* We timed out or were interrupted. */ 3133 else if (error) 3134 return (NULL); 3135 /* If recursed, assume caller knows the rules. */ 3136 else if (BUF_LOCKRECURSED(bp)) 3137 goto end; 3138 3139 /* 3140 * The buffer is locked. B_CACHE is cleared if the buffer is 3141 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 3142 * and for a VMIO buffer B_CACHE is adjusted according to the 3143 * backing VM cache. 3144 */ 3145 if (bp->b_flags & B_INVAL) 3146 bp->b_flags &= ~B_CACHE; 3147 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 3148 bp->b_flags |= B_CACHE; 3149 if (bp->b_flags & B_MANAGED) 3150 MPASS(bp->b_qindex == QUEUE_NONE); 3151 else 3152 bremfree(bp); 3153 3154 /* 3155 * check for size inconsistencies for non-VMIO case. 3156 */ 3157 if (bp->b_bcount != size) { 3158 if ((bp->b_flags & B_VMIO) == 0 || 3159 (size > bp->b_kvasize)) { 3160 if (bp->b_flags & B_DELWRI) { 3161 /* 3162 * If buffer is pinned and caller does 3163 * not want sleep waiting for it to be 3164 * unpinned, bail out 3165 * */ 3166 if (bp->b_pin_count > 0) { 3167 if (flags & GB_LOCK_NOWAIT) { 3168 bqrelse(bp); 3169 return (NULL); 3170 } else { 3171 bunpin_wait(bp); 3172 } 3173 } 3174 bp->b_flags |= B_NOCACHE; 3175 bwrite(bp); 3176 } else { 3177 if (LIST_EMPTY(&bp->b_dep)) { 3178 bp->b_flags |= B_RELBUF; 3179 brelse(bp); 3180 } else { 3181 bp->b_flags |= B_NOCACHE; 3182 bwrite(bp); 3183 } 3184 } 3185 goto loop; 3186 } 3187 } 3188 3189 /* 3190 * Handle the case of unmapped buffer which should 3191 * become mapped, or the buffer for which KVA 3192 * reservation is requested. 3193 */ 3194 bp_unmapped_get_kva(bp, blkno, size, flags); 3195 3196 /* 3197 * If the size is inconsistant in the VMIO case, we can resize 3198 * the buffer. This might lead to B_CACHE getting set or 3199 * cleared. If the size has not changed, B_CACHE remains 3200 * unchanged from its previous state. 3201 */ 3202 if (bp->b_bcount != size) 3203 allocbuf(bp, size); 3204 3205 KASSERT(bp->b_offset != NOOFFSET, 3206 ("getblk: no buffer offset")); 3207 3208 /* 3209 * A buffer with B_DELWRI set and B_CACHE clear must 3210 * be committed before we can return the buffer in 3211 * order to prevent the caller from issuing a read 3212 * ( due to B_CACHE not being set ) and overwriting 3213 * it. 3214 * 3215 * Most callers, including NFS and FFS, need this to 3216 * operate properly either because they assume they 3217 * can issue a read if B_CACHE is not set, or because 3218 * ( for example ) an uncached B_DELWRI might loop due 3219 * to softupdates re-dirtying the buffer. In the latter 3220 * case, B_CACHE is set after the first write completes, 3221 * preventing further loops. 3222 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 3223 * above while extending the buffer, we cannot allow the 3224 * buffer to remain with B_CACHE set after the write 3225 * completes or it will represent a corrupt state. To 3226 * deal with this we set B_NOCACHE to scrap the buffer 3227 * after the write. 3228 * 3229 * We might be able to do something fancy, like setting 3230 * B_CACHE in bwrite() except if B_DELWRI is already set, 3231 * so the below call doesn't set B_CACHE, but that gets real 3232 * confusing. This is much easier. 3233 */ 3234 3235 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 3236 bp->b_flags |= B_NOCACHE; 3237 bwrite(bp); 3238 goto loop; 3239 } 3240 bp->b_flags &= ~B_DONE; 3241 } else { 3242 /* 3243 * Buffer is not in-core, create new buffer. The buffer 3244 * returned by getnewbuf() is locked. Note that the returned 3245 * buffer is also considered valid (not marked B_INVAL). 3246 */ 3247 BO_RUNLOCK(bo); 3248 /* 3249 * If the user does not want us to create the buffer, bail out 3250 * here. 3251 */ 3252 if (flags & GB_NOCREAT) 3253 return NULL; 3254 if (numfreebuffers == 0 && TD_IS_IDLETHREAD(curthread)) 3255 return NULL; 3256 3257 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize; 3258 offset = blkno * bsize; 3259 vmio = vp->v_object != NULL; 3260 if (vmio) { 3261 maxsize = size + (offset & PAGE_MASK); 3262 } else { 3263 maxsize = size; 3264 /* Do not allow non-VMIO notmapped buffers. */ 3265 flags &= ~GB_UNMAPPED; 3266 } 3267 maxsize = imax(maxsize, bsize); 3268 3269 bp = getnewbuf(vp, slpflag, slptimeo, size, maxsize, flags); 3270 if (bp == NULL) { 3271 if (slpflag || slptimeo) 3272 return NULL; 3273 goto loop; 3274 } 3275 3276 /* 3277 * This code is used to make sure that a buffer is not 3278 * created while the getnewbuf routine is blocked. 3279 * This can be a problem whether the vnode is locked or not. 3280 * If the buffer is created out from under us, we have to 3281 * throw away the one we just created. 3282 * 3283 * Note: this must occur before we associate the buffer 3284 * with the vp especially considering limitations in 3285 * the splay tree implementation when dealing with duplicate 3286 * lblkno's. 3287 */ 3288 BO_LOCK(bo); 3289 if (gbincore(bo, blkno)) { 3290 BO_UNLOCK(bo); 3291 bp->b_flags |= B_INVAL; 3292 brelse(bp); 3293 goto loop; 3294 } 3295 3296 /* 3297 * Insert the buffer into the hash, so that it can 3298 * be found by incore. 3299 */ 3300 bp->b_blkno = bp->b_lblkno = blkno; 3301 bp->b_offset = offset; 3302 bgetvp(vp, bp); 3303 BO_UNLOCK(bo); 3304 3305 /* 3306 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 3307 * buffer size starts out as 0, B_CACHE will be set by 3308 * allocbuf() for the VMIO case prior to it testing the 3309 * backing store for validity. 3310 */ 3311 3312 if (vmio) { 3313 bp->b_flags |= B_VMIO; 3314 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 3315 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 3316 bp, vp->v_object, bp->b_bufobj->bo_object)); 3317 } else { 3318 bp->b_flags &= ~B_VMIO; 3319 KASSERT(bp->b_bufobj->bo_object == NULL, 3320 ("ARGH! has b_bufobj->bo_object %p %p\n", 3321 bp, bp->b_bufobj->bo_object)); 3322 BUF_CHECK_MAPPED(bp); 3323 } 3324 3325 allocbuf(bp, size); 3326 bp->b_flags &= ~B_DONE; 3327 } 3328 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 3329 BUF_ASSERT_HELD(bp); 3330end: 3331 KASSERT(bp->b_bufobj == bo, 3332 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 3333 return (bp); 3334} 3335 3336/* 3337 * Get an empty, disassociated buffer of given size. The buffer is initially 3338 * set to B_INVAL. 3339 */ 3340struct buf * 3341geteblk(int size, int flags) 3342{ 3343 struct buf *bp; 3344 int maxsize; 3345 3346 maxsize = (size + BKVAMASK) & ~BKVAMASK; 3347 while ((bp = getnewbuf(NULL, 0, 0, size, maxsize, flags)) == NULL) { 3348 if ((flags & GB_NOWAIT_BD) && 3349 (curthread->td_pflags & TDP_BUFNEED) != 0) 3350 return (NULL); 3351 } 3352 allocbuf(bp, size); 3353 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 3354 BUF_ASSERT_HELD(bp); 3355 return (bp); 3356} 3357 3358 3359/* 3360 * This code constitutes the buffer memory from either anonymous system 3361 * memory (in the case of non-VMIO operations) or from an associated 3362 * VM object (in the case of VMIO operations). This code is able to 3363 * resize a buffer up or down. 3364 * 3365 * Note that this code is tricky, and has many complications to resolve 3366 * deadlock or inconsistant data situations. Tread lightly!!! 3367 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 3368 * the caller. Calling this code willy nilly can result in the loss of data. 3369 * 3370 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 3371 * B_CACHE for the non-VMIO case. 3372 */ 3373 3374int 3375allocbuf(struct buf *bp, int size) 3376{ 3377 int newbsize, mbsize; 3378 int i; 3379 3380 BUF_ASSERT_HELD(bp); 3381 3382 if (bp->b_kvasize < size) 3383 panic("allocbuf: buffer too small"); 3384 3385 if ((bp->b_flags & B_VMIO) == 0) { 3386 caddr_t origbuf; 3387 int origbufsize; 3388 /* 3389 * Just get anonymous memory from the kernel. Don't 3390 * mess with B_CACHE. 3391 */ 3392 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3393 if (bp->b_flags & B_MALLOC) 3394 newbsize = mbsize; 3395 else 3396 newbsize = round_page(size); 3397 3398 if (newbsize < bp->b_bufsize) { 3399 /* 3400 * malloced buffers are not shrunk 3401 */ 3402 if (bp->b_flags & B_MALLOC) { 3403 if (newbsize) { 3404 bp->b_bcount = size; 3405 } else { 3406 free(bp->b_data, M_BIOBUF); 3407 if (bp->b_bufsize) { 3408 atomic_subtract_long( 3409 &bufmallocspace, 3410 bp->b_bufsize); 3411 bufspacewakeup(); 3412 bp->b_bufsize = 0; 3413 } 3414 bp->b_saveaddr = bp->b_kvabase; 3415 bp->b_data = bp->b_saveaddr; 3416 bp->b_bcount = 0; 3417 bp->b_flags &= ~B_MALLOC; 3418 } 3419 return 1; 3420 } 3421 vm_hold_free_pages(bp, newbsize); 3422 } else if (newbsize > bp->b_bufsize) { 3423 /* 3424 * We only use malloced memory on the first allocation. 3425 * and revert to page-allocated memory when the buffer 3426 * grows. 3427 */ 3428 /* 3429 * There is a potential smp race here that could lead 3430 * to bufmallocspace slightly passing the max. It 3431 * is probably extremely rare and not worth worrying 3432 * over. 3433 */ 3434 if ( (bufmallocspace < maxbufmallocspace) && 3435 (bp->b_bufsize == 0) && 3436 (mbsize <= PAGE_SIZE/2)) { 3437 3438 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 3439 bp->b_bufsize = mbsize; 3440 bp->b_bcount = size; 3441 bp->b_flags |= B_MALLOC; 3442 atomic_add_long(&bufmallocspace, mbsize); 3443 return 1; 3444 } 3445 origbuf = NULL; 3446 origbufsize = 0; 3447 /* 3448 * If the buffer is growing on its other-than-first allocation, 3449 * then we revert to the page-allocation scheme. 3450 */ 3451 if (bp->b_flags & B_MALLOC) { 3452 origbuf = bp->b_data; 3453 origbufsize = bp->b_bufsize; 3454 bp->b_data = bp->b_kvabase; 3455 if (bp->b_bufsize) { 3456 atomic_subtract_long(&bufmallocspace, 3457 bp->b_bufsize); 3458 bufspacewakeup(); 3459 bp->b_bufsize = 0; 3460 } 3461 bp->b_flags &= ~B_MALLOC; 3462 newbsize = round_page(newbsize); 3463 } 3464 vm_hold_load_pages( 3465 bp, 3466 (vm_offset_t) bp->b_data + bp->b_bufsize, 3467 (vm_offset_t) bp->b_data + newbsize); 3468 if (origbuf) { 3469 bcopy(origbuf, bp->b_data, origbufsize); 3470 free(origbuf, M_BIOBUF); 3471 } 3472 } 3473 } else { 3474 int desiredpages; 3475 3476 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3477 desiredpages = (size == 0) ? 0 : 3478 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 3479 3480 if (bp->b_flags & B_MALLOC) 3481 panic("allocbuf: VMIO buffer can't be malloced"); 3482 /* 3483 * Set B_CACHE initially if buffer is 0 length or will become 3484 * 0-length. 3485 */ 3486 if (size == 0 || bp->b_bufsize == 0) 3487 bp->b_flags |= B_CACHE; 3488 3489 if (newbsize < bp->b_bufsize) { 3490 /* 3491 * DEV_BSIZE aligned new buffer size is less then the 3492 * DEV_BSIZE aligned existing buffer size. Figure out 3493 * if we have to remove any pages. 3494 */ 3495 if (desiredpages < bp->b_npages) { 3496 vm_page_t m; 3497 3498 if ((bp->b_flags & B_UNMAPPED) == 0) { 3499 BUF_CHECK_MAPPED(bp); 3500 pmap_qremove((vm_offset_t)trunc_page( 3501 (vm_offset_t)bp->b_data) + 3502 (desiredpages << PAGE_SHIFT), 3503 (bp->b_npages - desiredpages)); 3504 } else 3505 BUF_CHECK_UNMAPPED(bp); 3506 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 3507 for (i = desiredpages; i < bp->b_npages; i++) { 3508 /* 3509 * the page is not freed here -- it 3510 * is the responsibility of 3511 * vnode_pager_setsize 3512 */ 3513 m = bp->b_pages[i]; 3514 KASSERT(m != bogus_page, 3515 ("allocbuf: bogus page found")); 3516 while (vm_page_sleep_if_busy(m, 3517 "biodep")) 3518 continue; 3519 3520 bp->b_pages[i] = NULL; 3521 vm_page_lock(m); 3522 vm_page_unwire(m, 0); 3523 vm_page_unlock(m); 3524 } 3525 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 3526 bp->b_npages = desiredpages; 3527 } 3528 } else if (size > bp->b_bcount) { 3529 /* 3530 * We are growing the buffer, possibly in a 3531 * byte-granular fashion. 3532 */ 3533 vm_object_t obj; 3534 vm_offset_t toff; 3535 vm_offset_t tinc; 3536 3537 /* 3538 * Step 1, bring in the VM pages from the object, 3539 * allocating them if necessary. We must clear 3540 * B_CACHE if these pages are not valid for the 3541 * range covered by the buffer. 3542 */ 3543 3544 obj = bp->b_bufobj->bo_object; 3545 3546 VM_OBJECT_WLOCK(obj); 3547 while (bp->b_npages < desiredpages) { 3548 vm_page_t m; 3549 3550 /* 3551 * We must allocate system pages since blocking 3552 * here could interfere with paging I/O, no 3553 * matter which process we are. 3554 * 3555 * Only exclusive busy can be tested here. 3556 * Blocking on shared busy might lead to 3557 * deadlocks once allocbuf() is called after 3558 * pages are vfs_busy_pages(). 3559 */ 3560 m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) + 3561 bp->b_npages, VM_ALLOC_NOBUSY | 3562 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED | 3563 VM_ALLOC_IGN_SBUSY | 3564 VM_ALLOC_COUNT(desiredpages - bp->b_npages)); 3565 if (m->valid == 0) 3566 bp->b_flags &= ~B_CACHE; 3567 bp->b_pages[bp->b_npages] = m; 3568 ++bp->b_npages; 3569 } 3570 3571 /* 3572 * Step 2. We've loaded the pages into the buffer, 3573 * we have to figure out if we can still have B_CACHE 3574 * set. Note that B_CACHE is set according to the 3575 * byte-granular range ( bcount and size ), new the 3576 * aligned range ( newbsize ). 3577 * 3578 * The VM test is against m->valid, which is DEV_BSIZE 3579 * aligned. Needless to say, the validity of the data 3580 * needs to also be DEV_BSIZE aligned. Note that this 3581 * fails with NFS if the server or some other client 3582 * extends the file's EOF. If our buffer is resized, 3583 * B_CACHE may remain set! XXX 3584 */ 3585 3586 toff = bp->b_bcount; 3587 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 3588 3589 while ((bp->b_flags & B_CACHE) && toff < size) { 3590 vm_pindex_t pi; 3591 3592 if (tinc > (size - toff)) 3593 tinc = size - toff; 3594 3595 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 3596 PAGE_SHIFT; 3597 3598 vfs_buf_test_cache( 3599 bp, 3600 bp->b_offset, 3601 toff, 3602 tinc, 3603 bp->b_pages[pi] 3604 ); 3605 toff += tinc; 3606 tinc = PAGE_SIZE; 3607 } 3608 VM_OBJECT_WUNLOCK(obj); 3609 3610 /* 3611 * Step 3, fixup the KVM pmap. 3612 */ 3613 if ((bp->b_flags & B_UNMAPPED) == 0) 3614 bpmap_qenter(bp); 3615 else 3616 BUF_CHECK_UNMAPPED(bp); 3617 } 3618 } 3619 if (newbsize < bp->b_bufsize) 3620 bufspacewakeup(); 3621 bp->b_bufsize = newbsize; /* actual buffer allocation */ 3622 bp->b_bcount = size; /* requested buffer size */ 3623 return 1; 3624} 3625 3626extern int inflight_transient_maps; 3627 3628void 3629biodone(struct bio *bp) 3630{ 3631 struct mtx *mtxp; 3632 void (*done)(struct bio *); 3633 vm_offset_t start, end; 3634 3635 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) { 3636 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING; 3637 bp->bio_flags |= BIO_UNMAPPED; 3638 start = trunc_page((vm_offset_t)bp->bio_data); 3639 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length); 3640 pmap_qremove(start, OFF_TO_IDX(end - start)); 3641 vmem_free(transient_arena, start, end - start); 3642 atomic_add_int(&inflight_transient_maps, -1); 3643 } 3644 done = bp->bio_done; 3645 if (done == NULL) { 3646 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3647 mtx_lock(mtxp); 3648 bp->bio_flags |= BIO_DONE; 3649 wakeup(bp); 3650 mtx_unlock(mtxp); 3651 } else { 3652 bp->bio_flags |= BIO_DONE; 3653 done(bp); 3654 } 3655} 3656 3657/* 3658 * Wait for a BIO to finish. 3659 */ 3660int 3661biowait(struct bio *bp, const char *wchan) 3662{ 3663 struct mtx *mtxp; 3664 3665 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3666 mtx_lock(mtxp); 3667 while ((bp->bio_flags & BIO_DONE) == 0) 3668 msleep(bp, mtxp, PRIBIO, wchan, 0); 3669 mtx_unlock(mtxp); 3670 if (bp->bio_error != 0) 3671 return (bp->bio_error); 3672 if (!(bp->bio_flags & BIO_ERROR)) 3673 return (0); 3674 return (EIO); 3675} 3676 3677void 3678biofinish(struct bio *bp, struct devstat *stat, int error) 3679{ 3680 3681 if (error) { 3682 bp->bio_error = error; 3683 bp->bio_flags |= BIO_ERROR; 3684 } 3685 if (stat != NULL) 3686 devstat_end_transaction_bio(stat, bp); 3687 biodone(bp); 3688} 3689 3690/* 3691 * bufwait: 3692 * 3693 * Wait for buffer I/O completion, returning error status. The buffer 3694 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3695 * error and cleared. 3696 */ 3697int 3698bufwait(struct buf *bp) 3699{ 3700 if (bp->b_iocmd == BIO_READ) 3701 bwait(bp, PRIBIO, "biord"); 3702 else 3703 bwait(bp, PRIBIO, "biowr"); 3704 if (bp->b_flags & B_EINTR) { 3705 bp->b_flags &= ~B_EINTR; 3706 return (EINTR); 3707 } 3708 if (bp->b_ioflags & BIO_ERROR) { 3709 return (bp->b_error ? bp->b_error : EIO); 3710 } else { 3711 return (0); 3712 } 3713} 3714 3715 /* 3716 * Call back function from struct bio back up to struct buf. 3717 */ 3718static void 3719bufdonebio(struct bio *bip) 3720{ 3721 struct buf *bp; 3722 3723 bp = bip->bio_caller2; 3724 bp->b_resid = bp->b_bcount - bip->bio_completed; 3725 bp->b_resid = bip->bio_resid; /* XXX: remove */ 3726 bp->b_ioflags = bip->bio_flags; 3727 bp->b_error = bip->bio_error; 3728 if (bp->b_error) 3729 bp->b_ioflags |= BIO_ERROR; 3730 bufdone(bp); 3731 g_destroy_bio(bip); 3732} 3733 3734void 3735dev_strategy(struct cdev *dev, struct buf *bp) 3736{ 3737 struct cdevsw *csw; 3738 int ref; 3739 3740 KASSERT(dev->si_refcount > 0, 3741 ("dev_strategy on un-referenced struct cdev *(%s) %p", 3742 devtoname(dev), dev)); 3743 3744 csw = dev_refthread(dev, &ref); 3745 dev_strategy_csw(dev, csw, bp); 3746 dev_relthread(dev, ref); 3747} 3748 3749void 3750dev_strategy_csw(struct cdev *dev, struct cdevsw *csw, struct buf *bp) 3751{ 3752 struct bio *bip; 3753 3754 KASSERT(bp->b_iocmd == BIO_READ || bp->b_iocmd == BIO_WRITE, 3755 ("b_iocmd botch")); 3756 KASSERT(((dev->si_flags & SI_ETERNAL) != 0 && csw != NULL) || 3757 dev->si_threadcount > 0, 3758 ("dev_strategy_csw threadcount cdev *(%s) %p", devtoname(dev), 3759 dev)); 3760 if (csw == NULL) { 3761 bp->b_error = ENXIO; 3762 bp->b_ioflags = BIO_ERROR; 3763 bufdone(bp); 3764 return; 3765 } 3766 for (;;) { 3767 bip = g_new_bio(); 3768 if (bip != NULL) 3769 break; 3770 /* Try again later */ 3771 tsleep(&bp, PRIBIO, "dev_strat", hz/10); 3772 } 3773 bip->bio_cmd = bp->b_iocmd; 3774 bip->bio_offset = bp->b_iooffset; 3775 bip->bio_length = bp->b_bcount; 3776 bip->bio_bcount = bp->b_bcount; /* XXX: remove */ 3777 bdata2bio(bp, bip); 3778 bip->bio_done = bufdonebio; 3779 bip->bio_caller2 = bp; 3780 bip->bio_dev = dev; 3781 (*csw->d_strategy)(bip); 3782} 3783 3784/* 3785 * bufdone: 3786 * 3787 * Finish I/O on a buffer, optionally calling a completion function. 3788 * This is usually called from an interrupt so process blocking is 3789 * not allowed. 3790 * 3791 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3792 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3793 * assuming B_INVAL is clear. 3794 * 3795 * For the VMIO case, we set B_CACHE if the op was a read and no 3796 * read error occured, or if the op was a write. B_CACHE is never 3797 * set if the buffer is invalid or otherwise uncacheable. 3798 * 3799 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3800 * initiator to leave B_INVAL set to brelse the buffer out of existance 3801 * in the biodone routine. 3802 */ 3803void 3804bufdone(struct buf *bp) 3805{ 3806 struct bufobj *dropobj; 3807 void (*biodone)(struct buf *); 3808 3809 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 3810 dropobj = NULL; 3811 3812 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 3813 BUF_ASSERT_HELD(bp); 3814 3815 runningbufwakeup(bp); 3816 if (bp->b_iocmd == BIO_WRITE) 3817 dropobj = bp->b_bufobj; 3818 /* call optional completion function if requested */ 3819 if (bp->b_iodone != NULL) { 3820 biodone = bp->b_iodone; 3821 bp->b_iodone = NULL; 3822 (*biodone) (bp); 3823 if (dropobj) 3824 bufobj_wdrop(dropobj); 3825 return; 3826 } 3827 3828 bufdone_finish(bp); 3829 3830 if (dropobj) 3831 bufobj_wdrop(dropobj); 3832} 3833 3834void 3835bufdone_finish(struct buf *bp) 3836{ 3837 BUF_ASSERT_HELD(bp); 3838 3839 if (!LIST_EMPTY(&bp->b_dep)) 3840 buf_complete(bp); 3841 3842 if (bp->b_flags & B_VMIO) { 3843 vm_ooffset_t foff; 3844 vm_page_t m; 3845 vm_object_t obj; 3846 struct vnode *vp; 3847 int bogus, i, iosize; 3848 3849 obj = bp->b_bufobj->bo_object; 3850 KASSERT(obj->paging_in_progress >= bp->b_npages, 3851 ("biodone_finish: paging in progress(%d) < b_npages(%d)", 3852 obj->paging_in_progress, bp->b_npages)); 3853 3854 vp = bp->b_vp; 3855 KASSERT(vp->v_holdcnt > 0, 3856 ("biodone_finish: vnode %p has zero hold count", vp)); 3857 KASSERT(vp->v_object != NULL, 3858 ("biodone_finish: vnode %p has no vm_object", vp)); 3859 3860 foff = bp->b_offset; 3861 KASSERT(bp->b_offset != NOOFFSET, 3862 ("biodone_finish: bp %p has no buffer offset", bp)); 3863 3864 /* 3865 * Set B_CACHE if the op was a normal read and no error 3866 * occured. B_CACHE is set for writes in the b*write() 3867 * routines. 3868 */ 3869 iosize = bp->b_bcount - bp->b_resid; 3870 if (bp->b_iocmd == BIO_READ && 3871 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 3872 !(bp->b_ioflags & BIO_ERROR)) { 3873 bp->b_flags |= B_CACHE; 3874 } 3875 bogus = 0; 3876 VM_OBJECT_WLOCK(obj); 3877 for (i = 0; i < bp->b_npages; i++) { 3878 int bogusflag = 0; 3879 int resid; 3880 3881 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 3882 if (resid > iosize) 3883 resid = iosize; 3884 3885 /* 3886 * cleanup bogus pages, restoring the originals 3887 */ 3888 m = bp->b_pages[i]; 3889 if (m == bogus_page) { 3890 bogus = bogusflag = 1; 3891 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3892 if (m == NULL) 3893 panic("biodone: page disappeared!"); 3894 bp->b_pages[i] = m; 3895 } 3896 KASSERT(OFF_TO_IDX(foff) == m->pindex, 3897 ("biodone_finish: foff(%jd)/pindex(%ju) mismatch", 3898 (intmax_t)foff, (uintmax_t)m->pindex)); 3899 3900 /* 3901 * In the write case, the valid and clean bits are 3902 * already changed correctly ( see bdwrite() ), so we 3903 * only need to do this here in the read case. 3904 */ 3905 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 3906 KASSERT((m->dirty & vm_page_bits(foff & 3907 PAGE_MASK, resid)) == 0, ("bufdone_finish:" 3908 " page %p has unexpected dirty bits", m)); 3909 vfs_page_set_valid(bp, foff, m); 3910 } 3911 3912 vm_page_sunbusy(m); 3913 vm_object_pip_subtract(obj, 1); 3914 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3915 iosize -= resid; 3916 } 3917 vm_object_pip_wakeupn(obj, 0); 3918 VM_OBJECT_WUNLOCK(obj); 3919 if (bogus && (bp->b_flags & B_UNMAPPED) == 0) { 3920 BUF_CHECK_MAPPED(bp); 3921 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3922 bp->b_pages, bp->b_npages); 3923 } 3924 } 3925 3926 /* 3927 * For asynchronous completions, release the buffer now. The brelse 3928 * will do a wakeup there if necessary - so no need to do a wakeup 3929 * here in the async case. The sync case always needs to do a wakeup. 3930 */ 3931 3932 if (bp->b_flags & B_ASYNC) { 3933 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 3934 brelse(bp); 3935 else 3936 bqrelse(bp); 3937 } else 3938 bdone(bp); 3939} 3940 3941/* 3942 * This routine is called in lieu of iodone in the case of 3943 * incomplete I/O. This keeps the busy status for pages 3944 * consistant. 3945 */ 3946void 3947vfs_unbusy_pages(struct buf *bp) 3948{ 3949 int i; 3950 vm_object_t obj; 3951 vm_page_t m; 3952 3953 runningbufwakeup(bp); 3954 if (!(bp->b_flags & B_VMIO)) 3955 return; 3956 3957 obj = bp->b_bufobj->bo_object; 3958 VM_OBJECT_WLOCK(obj); 3959 for (i = 0; i < bp->b_npages; i++) { 3960 m = bp->b_pages[i]; 3961 if (m == bogus_page) { 3962 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 3963 if (!m) 3964 panic("vfs_unbusy_pages: page missing\n"); 3965 bp->b_pages[i] = m; 3966 if ((bp->b_flags & B_UNMAPPED) == 0) { 3967 BUF_CHECK_MAPPED(bp); 3968 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3969 bp->b_pages, bp->b_npages); 3970 } else 3971 BUF_CHECK_UNMAPPED(bp); 3972 } 3973 vm_object_pip_subtract(obj, 1); 3974 vm_page_sunbusy(m); 3975 } 3976 vm_object_pip_wakeupn(obj, 0); 3977 VM_OBJECT_WUNLOCK(obj); 3978} 3979 3980/* 3981 * vfs_page_set_valid: 3982 * 3983 * Set the valid bits in a page based on the supplied offset. The 3984 * range is restricted to the buffer's size. 3985 * 3986 * This routine is typically called after a read completes. 3987 */ 3988static void 3989vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3990{ 3991 vm_ooffset_t eoff; 3992 3993 /* 3994 * Compute the end offset, eoff, such that [off, eoff) does not span a 3995 * page boundary and eoff is not greater than the end of the buffer. 3996 * The end of the buffer, in this case, is our file EOF, not the 3997 * allocation size of the buffer. 3998 */ 3999 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 4000 if (eoff > bp->b_offset + bp->b_bcount) 4001 eoff = bp->b_offset + bp->b_bcount; 4002 4003 /* 4004 * Set valid range. This is typically the entire buffer and thus the 4005 * entire page. 4006 */ 4007 if (eoff > off) 4008 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off); 4009} 4010 4011/* 4012 * vfs_page_set_validclean: 4013 * 4014 * Set the valid bits and clear the dirty bits in a page based on the 4015 * supplied offset. The range is restricted to the buffer's size. 4016 */ 4017static void 4018vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4019{ 4020 vm_ooffset_t soff, eoff; 4021 4022 /* 4023 * Start and end offsets in buffer. eoff - soff may not cross a 4024 * page boundry or cross the end of the buffer. The end of the 4025 * buffer, in this case, is our file EOF, not the allocation size 4026 * of the buffer. 4027 */ 4028 soff = off; 4029 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4030 if (eoff > bp->b_offset + bp->b_bcount) 4031 eoff = bp->b_offset + bp->b_bcount; 4032 4033 /* 4034 * Set valid range. This is typically the entire buffer and thus the 4035 * entire page. 4036 */ 4037 if (eoff > soff) { 4038 vm_page_set_validclean( 4039 m, 4040 (vm_offset_t) (soff & PAGE_MASK), 4041 (vm_offset_t) (eoff - soff) 4042 ); 4043 } 4044} 4045 4046/* 4047 * Ensure that all buffer pages are not exclusive busied. If any page is 4048 * exclusive busy, drain it. 4049 */ 4050void 4051vfs_drain_busy_pages(struct buf *bp) 4052{ 4053 vm_page_t m; 4054 int i, last_busied; 4055 4056 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object); 4057 last_busied = 0; 4058 for (i = 0; i < bp->b_npages; i++) { 4059 m = bp->b_pages[i]; 4060 if (vm_page_xbusied(m)) { 4061 for (; last_busied < i; last_busied++) 4062 vm_page_sbusy(bp->b_pages[last_busied]); 4063 while (vm_page_xbusied(m)) { 4064 vm_page_lock(m); 4065 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4066 vm_page_busy_sleep(m, "vbpage"); 4067 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4068 } 4069 } 4070 } 4071 for (i = 0; i < last_busied; i++) 4072 vm_page_sunbusy(bp->b_pages[i]); 4073} 4074 4075/* 4076 * This routine is called before a device strategy routine. 4077 * It is used to tell the VM system that paging I/O is in 4078 * progress, and treat the pages associated with the buffer 4079 * almost as being exclusive busy. Also the object paging_in_progress 4080 * flag is handled to make sure that the object doesn't become 4081 * inconsistant. 4082 * 4083 * Since I/O has not been initiated yet, certain buffer flags 4084 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 4085 * and should be ignored. 4086 */ 4087void 4088vfs_busy_pages(struct buf *bp, int clear_modify) 4089{ 4090 int i, bogus; 4091 vm_object_t obj; 4092 vm_ooffset_t foff; 4093 vm_page_t m; 4094 4095 if (!(bp->b_flags & B_VMIO)) 4096 return; 4097 4098 obj = bp->b_bufobj->bo_object; 4099 foff = bp->b_offset; 4100 KASSERT(bp->b_offset != NOOFFSET, 4101 ("vfs_busy_pages: no buffer offset")); 4102 VM_OBJECT_WLOCK(obj); 4103 vfs_drain_busy_pages(bp); 4104 if (bp->b_bufsize != 0) 4105 vfs_setdirty_locked_object(bp); 4106 bogus = 0; 4107 for (i = 0; i < bp->b_npages; i++) { 4108 m = bp->b_pages[i]; 4109 4110 if ((bp->b_flags & B_CLUSTER) == 0) { 4111 vm_object_pip_add(obj, 1); 4112 vm_page_sbusy(m); 4113 } 4114 /* 4115 * When readying a buffer for a read ( i.e 4116 * clear_modify == 0 ), it is important to do 4117 * bogus_page replacement for valid pages in 4118 * partially instantiated buffers. Partially 4119 * instantiated buffers can, in turn, occur when 4120 * reconstituting a buffer from its VM backing store 4121 * base. We only have to do this if B_CACHE is 4122 * clear ( which causes the I/O to occur in the 4123 * first place ). The replacement prevents the read 4124 * I/O from overwriting potentially dirty VM-backed 4125 * pages. XXX bogus page replacement is, uh, bogus. 4126 * It may not work properly with small-block devices. 4127 * We need to find a better way. 4128 */ 4129 if (clear_modify) { 4130 pmap_remove_write(m); 4131 vfs_page_set_validclean(bp, foff, m); 4132 } else if (m->valid == VM_PAGE_BITS_ALL && 4133 (bp->b_flags & B_CACHE) == 0) { 4134 bp->b_pages[i] = bogus_page; 4135 bogus++; 4136 } 4137 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4138 } 4139 VM_OBJECT_WUNLOCK(obj); 4140 if (bogus && (bp->b_flags & B_UNMAPPED) == 0) { 4141 BUF_CHECK_MAPPED(bp); 4142 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4143 bp->b_pages, bp->b_npages); 4144 } 4145} 4146 4147/* 4148 * vfs_bio_set_valid: 4149 * 4150 * Set the range within the buffer to valid. The range is 4151 * relative to the beginning of the buffer, b_offset. Note that 4152 * b_offset itself may be offset from the beginning of the first 4153 * page. 4154 */ 4155void 4156vfs_bio_set_valid(struct buf *bp, int base, int size) 4157{ 4158 int i, n; 4159 vm_page_t m; 4160 4161 if (!(bp->b_flags & B_VMIO)) 4162 return; 4163 4164 /* 4165 * Fixup base to be relative to beginning of first page. 4166 * Set initial n to be the maximum number of bytes in the 4167 * first page that can be validated. 4168 */ 4169 base += (bp->b_offset & PAGE_MASK); 4170 n = PAGE_SIZE - (base & PAGE_MASK); 4171 4172 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4173 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4174 m = bp->b_pages[i]; 4175 if (n > size) 4176 n = size; 4177 vm_page_set_valid_range(m, base & PAGE_MASK, n); 4178 base += n; 4179 size -= n; 4180 n = PAGE_SIZE; 4181 } 4182 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4183} 4184 4185/* 4186 * vfs_bio_clrbuf: 4187 * 4188 * If the specified buffer is a non-VMIO buffer, clear the entire 4189 * buffer. If the specified buffer is a VMIO buffer, clear and 4190 * validate only the previously invalid portions of the buffer. 4191 * This routine essentially fakes an I/O, so we need to clear 4192 * BIO_ERROR and B_INVAL. 4193 * 4194 * Note that while we only theoretically need to clear through b_bcount, 4195 * we go ahead and clear through b_bufsize. 4196 */ 4197void 4198vfs_bio_clrbuf(struct buf *bp) 4199{ 4200 int i, j, mask, sa, ea, slide; 4201 4202 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 4203 clrbuf(bp); 4204 return; 4205 } 4206 bp->b_flags &= ~B_INVAL; 4207 bp->b_ioflags &= ~BIO_ERROR; 4208 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4209 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 4210 (bp->b_offset & PAGE_MASK) == 0) { 4211 if (bp->b_pages[0] == bogus_page) 4212 goto unlock; 4213 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 4214 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object); 4215 if ((bp->b_pages[0]->valid & mask) == mask) 4216 goto unlock; 4217 if ((bp->b_pages[0]->valid & mask) == 0) { 4218 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize); 4219 bp->b_pages[0]->valid |= mask; 4220 goto unlock; 4221 } 4222 } 4223 sa = bp->b_offset & PAGE_MASK; 4224 slide = 0; 4225 for (i = 0; i < bp->b_npages; i++, sa = 0) { 4226 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize); 4227 ea = slide & PAGE_MASK; 4228 if (ea == 0) 4229 ea = PAGE_SIZE; 4230 if (bp->b_pages[i] == bogus_page) 4231 continue; 4232 j = sa / DEV_BSIZE; 4233 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 4234 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object); 4235 if ((bp->b_pages[i]->valid & mask) == mask) 4236 continue; 4237 if ((bp->b_pages[i]->valid & mask) == 0) 4238 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa); 4239 else { 4240 for (; sa < ea; sa += DEV_BSIZE, j++) { 4241 if ((bp->b_pages[i]->valid & (1 << j)) == 0) { 4242 pmap_zero_page_area(bp->b_pages[i], 4243 sa, DEV_BSIZE); 4244 } 4245 } 4246 } 4247 bp->b_pages[i]->valid |= mask; 4248 } 4249unlock: 4250 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4251 bp->b_resid = 0; 4252} 4253 4254void 4255vfs_bio_bzero_buf(struct buf *bp, int base, int size) 4256{ 4257 vm_page_t m; 4258 int i, n; 4259 4260 if ((bp->b_flags & B_UNMAPPED) == 0) { 4261 BUF_CHECK_MAPPED(bp); 4262 bzero(bp->b_data + base, size); 4263 } else { 4264 BUF_CHECK_UNMAPPED(bp); 4265 n = PAGE_SIZE - (base & PAGE_MASK); 4266 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4267 m = bp->b_pages[i]; 4268 if (n > size) 4269 n = size; 4270 pmap_zero_page_area(m, base & PAGE_MASK, n); 4271 base += n; 4272 size -= n; 4273 n = PAGE_SIZE; 4274 } 4275 } 4276} 4277 4278/* 4279 * vm_hold_load_pages and vm_hold_free_pages get pages into 4280 * a buffers address space. The pages are anonymous and are 4281 * not associated with a file object. 4282 */ 4283static void 4284vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4285{ 4286 vm_offset_t pg; 4287 vm_page_t p; 4288 int index; 4289 4290 BUF_CHECK_MAPPED(bp); 4291 4292 to = round_page(to); 4293 from = round_page(from); 4294 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4295 4296 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 4297tryagain: 4298 /* 4299 * note: must allocate system pages since blocking here 4300 * could interfere with paging I/O, no matter which 4301 * process we are. 4302 */ 4303 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ | 4304 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT)); 4305 if (p == NULL) { 4306 VM_WAIT; 4307 goto tryagain; 4308 } 4309 pmap_qenter(pg, &p, 1); 4310 bp->b_pages[index] = p; 4311 } 4312 bp->b_npages = index; 4313} 4314 4315/* Return pages associated with this buf to the vm system */ 4316static void 4317vm_hold_free_pages(struct buf *bp, int newbsize) 4318{ 4319 vm_offset_t from; 4320 vm_page_t p; 4321 int index, newnpages; 4322 4323 BUF_CHECK_MAPPED(bp); 4324 4325 from = round_page((vm_offset_t)bp->b_data + newbsize); 4326 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4327 if (bp->b_npages > newnpages) 4328 pmap_qremove(from, bp->b_npages - newnpages); 4329 for (index = newnpages; index < bp->b_npages; index++) { 4330 p = bp->b_pages[index]; 4331 bp->b_pages[index] = NULL; 4332 if (vm_page_sbusied(p)) 4333 printf("vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 4334 (intmax_t)bp->b_blkno, (intmax_t)bp->b_lblkno); 4335 p->wire_count--; 4336 vm_page_free(p); 4337 atomic_subtract_int(&cnt.v_wire_count, 1); 4338 } 4339 bp->b_npages = newnpages; 4340} 4341 4342/* 4343 * Map an IO request into kernel virtual address space. 4344 * 4345 * All requests are (re)mapped into kernel VA space. 4346 * Notice that we use b_bufsize for the size of the buffer 4347 * to be mapped. b_bcount might be modified by the driver. 4348 * 4349 * Note that even if the caller determines that the address space should 4350 * be valid, a race or a smaller-file mapped into a larger space may 4351 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 4352 * check the return value. 4353 */ 4354int 4355vmapbuf(struct buf *bp, int mapbuf) 4356{ 4357 caddr_t kva; 4358 vm_prot_t prot; 4359 int pidx; 4360 4361 if (bp->b_bufsize < 0) 4362 return (-1); 4363 prot = VM_PROT_READ; 4364 if (bp->b_iocmd == BIO_READ) 4365 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 4366 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 4367 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages, 4368 btoc(MAXPHYS))) < 0) 4369 return (-1); 4370 bp->b_npages = pidx; 4371 if (mapbuf || !unmapped_buf_allowed) { 4372 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx); 4373 kva = bp->b_saveaddr; 4374 bp->b_saveaddr = bp->b_data; 4375 bp->b_data = kva + (((vm_offset_t)bp->b_data) & PAGE_MASK); 4376 bp->b_flags &= ~B_UNMAPPED; 4377 } else { 4378 bp->b_flags |= B_UNMAPPED; 4379 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK; 4380 bp->b_saveaddr = bp->b_data; 4381 bp->b_data = unmapped_buf; 4382 } 4383 return(0); 4384} 4385 4386/* 4387 * Free the io map PTEs associated with this IO operation. 4388 * We also invalidate the TLB entries and restore the original b_addr. 4389 */ 4390void 4391vunmapbuf(struct buf *bp) 4392{ 4393 int npages; 4394 4395 npages = bp->b_npages; 4396 if (bp->b_flags & B_UNMAPPED) 4397 bp->b_flags &= ~B_UNMAPPED; 4398 else 4399 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 4400 vm_page_unhold_pages(bp->b_pages, npages); 4401 4402 bp->b_data = bp->b_saveaddr; 4403} 4404 4405void 4406bdone(struct buf *bp) 4407{ 4408 struct mtx *mtxp; 4409 4410 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4411 mtx_lock(mtxp); 4412 bp->b_flags |= B_DONE; 4413 wakeup(bp); 4414 mtx_unlock(mtxp); 4415} 4416 4417void 4418bwait(struct buf *bp, u_char pri, const char *wchan) 4419{ 4420 struct mtx *mtxp; 4421 4422 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4423 mtx_lock(mtxp); 4424 while ((bp->b_flags & B_DONE) == 0) 4425 msleep(bp, mtxp, pri, wchan, 0); 4426 mtx_unlock(mtxp); 4427} 4428 4429int 4430bufsync(struct bufobj *bo, int waitfor) 4431{ 4432 4433 return (VOP_FSYNC(bo->__bo_vnode, waitfor, curthread)); 4434} 4435 4436void 4437bufstrategy(struct bufobj *bo, struct buf *bp) 4438{ 4439 int i = 0; 4440 struct vnode *vp; 4441 4442 vp = bp->b_vp; 4443 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 4444 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 4445 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 4446 i = VOP_STRATEGY(vp, bp); 4447 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 4448} 4449 4450void 4451bufobj_wrefl(struct bufobj *bo) 4452{ 4453 4454 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4455 ASSERT_BO_WLOCKED(bo); 4456 bo->bo_numoutput++; 4457} 4458 4459void 4460bufobj_wref(struct bufobj *bo) 4461{ 4462 4463 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4464 BO_LOCK(bo); 4465 bo->bo_numoutput++; 4466 BO_UNLOCK(bo); 4467} 4468 4469void 4470bufobj_wdrop(struct bufobj *bo) 4471{ 4472 4473 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 4474 BO_LOCK(bo); 4475 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 4476 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 4477 bo->bo_flag &= ~BO_WWAIT; 4478 wakeup(&bo->bo_numoutput); 4479 } 4480 BO_UNLOCK(bo); 4481} 4482 4483int 4484bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 4485{ 4486 int error; 4487 4488 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 4489 ASSERT_BO_WLOCKED(bo); 4490 error = 0; 4491 while (bo->bo_numoutput) { 4492 bo->bo_flag |= BO_WWAIT; 4493 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo), 4494 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 4495 if (error) 4496 break; 4497 } 4498 return (error); 4499} 4500 4501void 4502bpin(struct buf *bp) 4503{ 4504 struct mtx *mtxp; 4505 4506 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4507 mtx_lock(mtxp); 4508 bp->b_pin_count++; 4509 mtx_unlock(mtxp); 4510} 4511 4512void 4513bunpin(struct buf *bp) 4514{ 4515 struct mtx *mtxp; 4516 4517 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4518 mtx_lock(mtxp); 4519 if (--bp->b_pin_count == 0) 4520 wakeup(bp); 4521 mtx_unlock(mtxp); 4522} 4523 4524void 4525bunpin_wait(struct buf *bp) 4526{ 4527 struct mtx *mtxp; 4528 4529 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4530 mtx_lock(mtxp); 4531 while (bp->b_pin_count > 0) 4532 msleep(bp, mtxp, PRIBIO, "bwunpin", 0); 4533 mtx_unlock(mtxp); 4534} 4535 4536/* 4537 * Set bio_data or bio_ma for struct bio from the struct buf. 4538 */ 4539void 4540bdata2bio(struct buf *bp, struct bio *bip) 4541{ 4542 4543 if ((bp->b_flags & B_UNMAPPED) != 0) { 4544 KASSERT(unmapped_buf_allowed, ("unmapped")); 4545 bip->bio_ma = bp->b_pages; 4546 bip->bio_ma_n = bp->b_npages; 4547 bip->bio_data = unmapped_buf; 4548 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 4549 bip->bio_flags |= BIO_UNMAPPED; 4550 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) / 4551 PAGE_SIZE == bp->b_npages, 4552 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset, 4553 (long long)bip->bio_length, bip->bio_ma_n)); 4554 } else { 4555 bip->bio_data = bp->b_data; 4556 bip->bio_ma = NULL; 4557 } 4558} 4559 4560#include "opt_ddb.h" 4561#ifdef DDB 4562#include <ddb/ddb.h> 4563 4564/* DDB command to show buffer data */ 4565DB_SHOW_COMMAND(buffer, db_show_buffer) 4566{ 4567 /* get args */ 4568 struct buf *bp = (struct buf *)addr; 4569 4570 if (!have_addr) { 4571 db_printf("usage: show buffer <addr>\n"); 4572 return; 4573 } 4574 4575 db_printf("buf at %p\n", bp); 4576 db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n", 4577 (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags, 4578 PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS); 4579 db_printf( 4580 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 4581 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, " 4582 "b_dep = %p\n", 4583 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 4584 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 4585 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first); 4586 if (bp->b_npages) { 4587 int i; 4588 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 4589 for (i = 0; i < bp->b_npages; i++) { 4590 vm_page_t m; 4591 m = bp->b_pages[i]; 4592 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 4593 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 4594 if ((i + 1) < bp->b_npages) 4595 db_printf(","); 4596 } 4597 db_printf("\n"); 4598 } 4599 db_printf(" "); 4600 BUF_LOCKPRINTINFO(bp); 4601} 4602 4603DB_SHOW_COMMAND(lockedbufs, lockedbufs) 4604{ 4605 struct buf *bp; 4606 int i; 4607 4608 for (i = 0; i < nbuf; i++) { 4609 bp = &buf[i]; 4610 if (BUF_ISLOCKED(bp)) { 4611 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4612 db_printf("\n"); 4613 } 4614 } 4615} 4616 4617DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 4618{ 4619 struct vnode *vp; 4620 struct buf *bp; 4621 4622 if (!have_addr) { 4623 db_printf("usage: show vnodebufs <addr>\n"); 4624 return; 4625 } 4626 vp = (struct vnode *)addr; 4627 db_printf("Clean buffers:\n"); 4628 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 4629 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4630 db_printf("\n"); 4631 } 4632 db_printf("Dirty buffers:\n"); 4633 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 4634 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4635 db_printf("\n"); 4636 } 4637} 4638 4639DB_COMMAND(countfreebufs, db_coundfreebufs) 4640{ 4641 struct buf *bp; 4642 int i, used = 0, nfree = 0; 4643 4644 if (have_addr) { 4645 db_printf("usage: countfreebufs\n"); 4646 return; 4647 } 4648 4649 for (i = 0; i < nbuf; i++) { 4650 bp = &buf[i]; 4651 if ((bp->b_flags & B_INFREECNT) != 0) 4652 nfree++; 4653 else 4654 used++; 4655 } 4656 4657 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 4658 nfree + used); 4659 db_printf("numfreebuffers is %d\n", numfreebuffers); 4660} 4661#endif /* DDB */ 4662