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 307672 2016-10-20 13:12:19Z 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 acquisition"); 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 * Artificially 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_bufobj->bo_flag & BO_DEAD) != 0) { 1178 bp->b_flags |= B_INVAL | B_RELBUF; 1179 bp->b_flags &= ~B_CACHE; 1180 brelse(bp); 1181 return (ENXIO); 1182 } 1183 if (bp->b_flags & B_INVAL) { 1184 brelse(bp); 1185 return (0); 1186 } 1187 1188 if (bp->b_flags & B_BARRIER) 1189 barrierwrites++; 1190 1191 oldflags = bp->b_flags; 1192 1193 BUF_ASSERT_HELD(bp); 1194 1195 if (bp->b_pin_count > 0) 1196 bunpin_wait(bp); 1197 1198 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 1199 ("FFS background buffer should not get here %p", bp)); 1200 1201 vp = bp->b_vp; 1202 if (vp) 1203 vp_md = vp->v_vflag & VV_MD; 1204 else 1205 vp_md = 0; 1206 1207 /* 1208 * Mark the buffer clean. Increment the bufobj write count 1209 * before bundirty() call, to prevent other thread from seeing 1210 * empty dirty list and zero counter for writes in progress, 1211 * falsely indicating that the bufobj is clean. 1212 */ 1213 bufobj_wref(bp->b_bufobj); 1214 bundirty(bp); 1215 1216 bp->b_flags &= ~B_DONE; 1217 bp->b_ioflags &= ~BIO_ERROR; 1218 bp->b_flags |= B_CACHE; 1219 bp->b_iocmd = BIO_WRITE; 1220 1221 vfs_busy_pages(bp, 1); 1222 1223 /* 1224 * Normal bwrites pipeline writes 1225 */ 1226 bp->b_runningbufspace = bp->b_bufsize; 1227 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace); 1228 1229 if (!TD_IS_IDLETHREAD(curthread)) 1230 curthread->td_ru.ru_oublock++; 1231 if (oldflags & B_ASYNC) 1232 BUF_KERNPROC(bp); 1233 bp->b_iooffset = dbtob(bp->b_blkno); 1234 bstrategy(bp); 1235 1236 if ((oldflags & B_ASYNC) == 0) { 1237 int rtval = bufwait(bp); 1238 brelse(bp); 1239 return (rtval); 1240 } else if (space > hirunningspace) { 1241 /* 1242 * don't allow the async write to saturate the I/O 1243 * system. We will not deadlock here because 1244 * we are blocking waiting for I/O that is already in-progress 1245 * to complete. We do not block here if it is the update 1246 * or syncer daemon trying to clean up as that can lead 1247 * to deadlock. 1248 */ 1249 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 1250 waitrunningbufspace(); 1251 } 1252 1253 return (0); 1254} 1255 1256void 1257bufbdflush(struct bufobj *bo, struct buf *bp) 1258{ 1259 struct buf *nbp; 1260 1261 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 1262 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 1263 altbufferflushes++; 1264 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 1265 BO_LOCK(bo); 1266 /* 1267 * Try to find a buffer to flush. 1268 */ 1269 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 1270 if ((nbp->b_vflags & BV_BKGRDINPROG) || 1271 BUF_LOCK(nbp, 1272 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 1273 continue; 1274 if (bp == nbp) 1275 panic("bdwrite: found ourselves"); 1276 BO_UNLOCK(bo); 1277 /* Don't countdeps with the bo lock held. */ 1278 if (buf_countdeps(nbp, 0)) { 1279 BO_LOCK(bo); 1280 BUF_UNLOCK(nbp); 1281 continue; 1282 } 1283 if (nbp->b_flags & B_CLUSTEROK) { 1284 vfs_bio_awrite(nbp); 1285 } else { 1286 bremfree(nbp); 1287 bawrite(nbp); 1288 } 1289 dirtybufferflushes++; 1290 break; 1291 } 1292 if (nbp == NULL) 1293 BO_UNLOCK(bo); 1294 } 1295} 1296 1297/* 1298 * Delayed write. (Buffer is marked dirty). Do not bother writing 1299 * anything if the buffer is marked invalid. 1300 * 1301 * Note that since the buffer must be completely valid, we can safely 1302 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 1303 * biodone() in order to prevent getblk from writing the buffer 1304 * out synchronously. 1305 */ 1306void 1307bdwrite(struct buf *bp) 1308{ 1309 struct thread *td = curthread; 1310 struct vnode *vp; 1311 struct bufobj *bo; 1312 1313 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1314 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1315 KASSERT((bp->b_flags & B_BARRIER) == 0, 1316 ("Barrier request in delayed write %p", bp)); 1317 BUF_ASSERT_HELD(bp); 1318 1319 if (bp->b_flags & B_INVAL) { 1320 brelse(bp); 1321 return; 1322 } 1323 1324 /* 1325 * If we have too many dirty buffers, don't create any more. 1326 * If we are wildly over our limit, then force a complete 1327 * cleanup. Otherwise, just keep the situation from getting 1328 * out of control. Note that we have to avoid a recursive 1329 * disaster and not try to clean up after our own cleanup! 1330 */ 1331 vp = bp->b_vp; 1332 bo = bp->b_bufobj; 1333 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 1334 td->td_pflags |= TDP_INBDFLUSH; 1335 BO_BDFLUSH(bo, bp); 1336 td->td_pflags &= ~TDP_INBDFLUSH; 1337 } else 1338 recursiveflushes++; 1339 1340 bdirty(bp); 1341 /* 1342 * Set B_CACHE, indicating that the buffer is fully valid. This is 1343 * true even of NFS now. 1344 */ 1345 bp->b_flags |= B_CACHE; 1346 1347 /* 1348 * This bmap keeps the system from needing to do the bmap later, 1349 * perhaps when the system is attempting to do a sync. Since it 1350 * is likely that the indirect block -- or whatever other datastructure 1351 * that the filesystem needs is still in memory now, it is a good 1352 * thing to do this. Note also, that if the pageout daemon is 1353 * requesting a sync -- there might not be enough memory to do 1354 * the bmap then... So, this is important to do. 1355 */ 1356 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 1357 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 1358 } 1359 1360 /* 1361 * Set the *dirty* buffer range based upon the VM system dirty 1362 * pages. 1363 * 1364 * Mark the buffer pages as clean. We need to do this here to 1365 * satisfy the vnode_pager and the pageout daemon, so that it 1366 * thinks that the pages have been "cleaned". Note that since 1367 * the pages are in a delayed write buffer -- the VFS layer 1368 * "will" see that the pages get written out on the next sync, 1369 * or perhaps the cluster will be completed. 1370 */ 1371 vfs_clean_pages_dirty_buf(bp); 1372 bqrelse(bp); 1373 1374 /* 1375 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 1376 * due to the softdep code. 1377 */ 1378} 1379 1380/* 1381 * bdirty: 1382 * 1383 * Turn buffer into delayed write request. We must clear BIO_READ and 1384 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 1385 * itself to properly update it in the dirty/clean lists. We mark it 1386 * B_DONE to ensure that any asynchronization of the buffer properly 1387 * clears B_DONE ( else a panic will occur later ). 1388 * 1389 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 1390 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 1391 * should only be called if the buffer is known-good. 1392 * 1393 * Since the buffer is not on a queue, we do not update the numfreebuffers 1394 * count. 1395 * 1396 * The buffer must be on QUEUE_NONE. 1397 */ 1398void 1399bdirty(struct buf *bp) 1400{ 1401 1402 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 1403 bp, bp->b_vp, bp->b_flags); 1404 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1405 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1406 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1407 BUF_ASSERT_HELD(bp); 1408 bp->b_flags &= ~(B_RELBUF); 1409 bp->b_iocmd = BIO_WRITE; 1410 1411 if ((bp->b_flags & B_DELWRI) == 0) { 1412 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 1413 reassignbuf(bp); 1414 bdirtyadd(); 1415 } 1416} 1417 1418/* 1419 * bundirty: 1420 * 1421 * Clear B_DELWRI for buffer. 1422 * 1423 * Since the buffer is not on a queue, we do not update the numfreebuffers 1424 * count. 1425 * 1426 * The buffer must be on QUEUE_NONE. 1427 */ 1428 1429void 1430bundirty(struct buf *bp) 1431{ 1432 1433 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1434 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1435 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1436 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1437 BUF_ASSERT_HELD(bp); 1438 1439 if (bp->b_flags & B_DELWRI) { 1440 bp->b_flags &= ~B_DELWRI; 1441 reassignbuf(bp); 1442 bdirtysub(); 1443 } 1444 /* 1445 * Since it is now being written, we can clear its deferred write flag. 1446 */ 1447 bp->b_flags &= ~B_DEFERRED; 1448} 1449 1450/* 1451 * bawrite: 1452 * 1453 * Asynchronous write. Start output on a buffer, but do not wait for 1454 * it to complete. The buffer is released when the output completes. 1455 * 1456 * bwrite() ( or the VOP routine anyway ) is responsible for handling 1457 * B_INVAL buffers. Not us. 1458 */ 1459void 1460bawrite(struct buf *bp) 1461{ 1462 1463 bp->b_flags |= B_ASYNC; 1464 (void) bwrite(bp); 1465} 1466 1467/* 1468 * babarrierwrite: 1469 * 1470 * Asynchronous barrier write. Start output on a buffer, but do not 1471 * wait for it to complete. Place a write barrier after this write so 1472 * that this buffer and all buffers written before it are committed to 1473 * the disk before any buffers written after this write are committed 1474 * to the disk. The buffer is released when the output completes. 1475 */ 1476void 1477babarrierwrite(struct buf *bp) 1478{ 1479 1480 bp->b_flags |= B_ASYNC | B_BARRIER; 1481 (void) bwrite(bp); 1482} 1483 1484/* 1485 * bbarrierwrite: 1486 * 1487 * Synchronous barrier write. Start output on a buffer and wait for 1488 * it to complete. Place a write barrier after this write so that 1489 * this buffer and all buffers written before it are committed to 1490 * the disk before any buffers written after this write are committed 1491 * to the disk. The buffer is released when the output completes. 1492 */ 1493int 1494bbarrierwrite(struct buf *bp) 1495{ 1496 1497 bp->b_flags |= B_BARRIER; 1498 return (bwrite(bp)); 1499} 1500 1501/* 1502 * bwillwrite: 1503 * 1504 * Called prior to the locking of any vnodes when we are expecting to 1505 * write. We do not want to starve the buffer cache with too many 1506 * dirty buffers so we block here. By blocking prior to the locking 1507 * of any vnodes we attempt to avoid the situation where a locked vnode 1508 * prevents the various system daemons from flushing related buffers. 1509 */ 1510void 1511bwillwrite(void) 1512{ 1513 1514 if (numdirtybuffers >= hidirtybuffers) { 1515 mtx_lock(&bdirtylock); 1516 while (numdirtybuffers >= hidirtybuffers) { 1517 bdirtywait = 1; 1518 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4), 1519 "flswai", 0); 1520 } 1521 mtx_unlock(&bdirtylock); 1522 } 1523} 1524 1525/* 1526 * Return true if we have too many dirty buffers. 1527 */ 1528int 1529buf_dirty_count_severe(void) 1530{ 1531 1532 return(numdirtybuffers >= hidirtybuffers); 1533} 1534 1535static __noinline int 1536buf_vm_page_count_severe(void) 1537{ 1538 1539 KFAIL_POINT_CODE(DEBUG_FP, buf_pressure, return 1); 1540 1541 return vm_page_count_severe(); 1542} 1543 1544/* 1545 * brelse: 1546 * 1547 * Release a busy buffer and, if requested, free its resources. The 1548 * buffer will be stashed in the appropriate bufqueue[] allowing it 1549 * to be accessed later as a cache entity or reused for other purposes. 1550 */ 1551void 1552brelse(struct buf *bp) 1553{ 1554 int qindex; 1555 1556 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 1557 bp, bp->b_vp, bp->b_flags); 1558 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1559 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1560 1561 if (BUF_LOCKRECURSED(bp)) { 1562 /* 1563 * Do not process, in particular, do not handle the 1564 * B_INVAL/B_RELBUF and do not release to free list. 1565 */ 1566 BUF_UNLOCK(bp); 1567 return; 1568 } 1569 1570 if (bp->b_flags & B_MANAGED) { 1571 bqrelse(bp); 1572 return; 1573 } 1574 1575 if ((bp->b_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) { 1576 BO_LOCK(bp->b_bufobj); 1577 bp->b_vflags &= ~BV_BKGRDERR; 1578 BO_UNLOCK(bp->b_bufobj); 1579 bdirty(bp); 1580 } 1581 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 1582 bp->b_error == EIO && !(bp->b_flags & B_INVAL)) { 1583 /* 1584 * Failed write, redirty. Must clear BIO_ERROR to prevent 1585 * pages from being scrapped. If the error is anything 1586 * other than an I/O error (EIO), assume that retrying 1587 * is futile. 1588 */ 1589 bp->b_ioflags &= ~BIO_ERROR; 1590 bdirty(bp); 1591 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 1592 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 1593 /* 1594 * Either a failed I/O or we were asked to free or not 1595 * cache the buffer. 1596 */ 1597 bp->b_flags |= B_INVAL; 1598 if (!LIST_EMPTY(&bp->b_dep)) 1599 buf_deallocate(bp); 1600 if (bp->b_flags & B_DELWRI) 1601 bdirtysub(); 1602 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1603 if ((bp->b_flags & B_VMIO) == 0) { 1604 if (bp->b_bufsize) 1605 allocbuf(bp, 0); 1606 if (bp->b_vp) 1607 brelvp(bp); 1608 } 1609 } 1610 1611 /* 1612 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1613 * is called with B_DELWRI set, the underlying pages may wind up 1614 * getting freed causing a previous write (bdwrite()) to get 'lost' 1615 * because pages associated with a B_DELWRI bp are marked clean. 1616 * 1617 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1618 * if B_DELWRI is set. 1619 * 1620 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1621 * on pages to return pages to the VM page queues. 1622 */ 1623 if (bp->b_flags & B_DELWRI) 1624 bp->b_flags &= ~B_RELBUF; 1625 else if (buf_vm_page_count_severe()) { 1626 /* 1627 * BKGRDINPROG can only be set with the buf and bufobj 1628 * locks both held. We tolerate a race to clear it here. 1629 */ 1630 if (!(bp->b_vflags & BV_BKGRDINPROG)) 1631 bp->b_flags |= B_RELBUF; 1632 } 1633 1634 /* 1635 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1636 * constituted, not even NFS buffers now. Two flags effect this. If 1637 * B_INVAL, the struct buf is invalidated but the VM object is kept 1638 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1639 * 1640 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 1641 * invalidated. BIO_ERROR cannot be set for a failed write unless the 1642 * buffer is also B_INVAL because it hits the re-dirtying code above. 1643 * 1644 * Normally we can do this whether a buffer is B_DELWRI or not. If 1645 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1646 * the commit state and we cannot afford to lose the buffer. If the 1647 * buffer has a background write in progress, we need to keep it 1648 * around to prevent it from being reconstituted and starting a second 1649 * background write. 1650 */ 1651 if ((bp->b_flags & B_VMIO) 1652 && !(bp->b_vp->v_mount != NULL && 1653 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 1654 !vn_isdisk(bp->b_vp, NULL) && 1655 (bp->b_flags & B_DELWRI)) 1656 ) { 1657 1658 int i, j, resid; 1659 vm_page_t m; 1660 off_t foff; 1661 vm_pindex_t poff; 1662 vm_object_t obj; 1663 1664 obj = bp->b_bufobj->bo_object; 1665 1666 /* 1667 * Get the base offset and length of the buffer. Note that 1668 * in the VMIO case if the buffer block size is not 1669 * page-aligned then b_data pointer may not be page-aligned. 1670 * But our b_pages[] array *IS* page aligned. 1671 * 1672 * block sizes less then DEV_BSIZE (usually 512) are not 1673 * supported due to the page granularity bits (m->valid, 1674 * m->dirty, etc...). 1675 * 1676 * See man buf(9) for more information 1677 */ 1678 resid = bp->b_bufsize; 1679 foff = bp->b_offset; 1680 for (i = 0; i < bp->b_npages; i++) { 1681 int had_bogus = 0; 1682 1683 m = bp->b_pages[i]; 1684 1685 /* 1686 * If we hit a bogus page, fixup *all* the bogus pages 1687 * now. 1688 */ 1689 if (m == bogus_page) { 1690 poff = OFF_TO_IDX(bp->b_offset); 1691 had_bogus = 1; 1692 1693 VM_OBJECT_RLOCK(obj); 1694 for (j = i; j < bp->b_npages; j++) { 1695 vm_page_t mtmp; 1696 mtmp = bp->b_pages[j]; 1697 if (mtmp == bogus_page) { 1698 mtmp = vm_page_lookup(obj, poff + j); 1699 if (!mtmp) { 1700 panic("brelse: page missing\n"); 1701 } 1702 bp->b_pages[j] = mtmp; 1703 } 1704 } 1705 VM_OBJECT_RUNLOCK(obj); 1706 1707 if ((bp->b_flags & (B_INVAL | B_UNMAPPED)) == 0) { 1708 BUF_CHECK_MAPPED(bp); 1709 pmap_qenter( 1710 trunc_page((vm_offset_t)bp->b_data), 1711 bp->b_pages, bp->b_npages); 1712 } 1713 m = bp->b_pages[i]; 1714 } 1715 if ((bp->b_flags & B_NOCACHE) || 1716 (bp->b_ioflags & BIO_ERROR && 1717 bp->b_iocmd == BIO_READ)) { 1718 int poffset = foff & PAGE_MASK; 1719 int presid = resid > (PAGE_SIZE - poffset) ? 1720 (PAGE_SIZE - poffset) : resid; 1721 1722 KASSERT(presid >= 0, ("brelse: extra page")); 1723 VM_OBJECT_WLOCK(obj); 1724 while (vm_page_xbusied(m)) { 1725 vm_page_lock(m); 1726 VM_OBJECT_WUNLOCK(obj); 1727 vm_page_busy_sleep(m, "mbncsh", true); 1728 VM_OBJECT_WLOCK(obj); 1729 } 1730 if (pmap_page_wired_mappings(m) == 0) 1731 vm_page_set_invalid(m, poffset, presid); 1732 VM_OBJECT_WUNLOCK(obj); 1733 if (had_bogus) 1734 printf("avoided corruption bug in bogus_page/brelse code\n"); 1735 } 1736 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1737 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1738 } 1739 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1740 vfs_vmio_release(bp); 1741 1742 } else if (bp->b_flags & B_VMIO) { 1743 1744 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1745 vfs_vmio_release(bp); 1746 } 1747 1748 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) { 1749 if (bp->b_bufsize != 0) 1750 allocbuf(bp, 0); 1751 if (bp->b_vp != NULL) 1752 brelvp(bp); 1753 } 1754 1755 /* 1756 * If the buffer has junk contents signal it and eventually 1757 * clean up B_DELWRI and diassociate the vnode so that gbincore() 1758 * doesn't find it. 1759 */ 1760 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 1761 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 1762 bp->b_flags |= B_INVAL; 1763 if (bp->b_flags & B_INVAL) { 1764 if (bp->b_flags & B_DELWRI) 1765 bundirty(bp); 1766 if (bp->b_vp) 1767 brelvp(bp); 1768 } 1769 1770 /* buffers with no memory */ 1771 if (bp->b_bufsize == 0) { 1772 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1773 if (bp->b_vflags & BV_BKGRDINPROG) 1774 panic("losing buffer 1"); 1775 if (bp->b_kvasize) 1776 qindex = QUEUE_EMPTYKVA; 1777 else 1778 qindex = QUEUE_EMPTY; 1779 bp->b_flags |= B_AGE; 1780 /* buffers with junk contents */ 1781 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 1782 (bp->b_ioflags & BIO_ERROR)) { 1783 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1784 if (bp->b_vflags & BV_BKGRDINPROG) 1785 panic("losing buffer 2"); 1786 qindex = QUEUE_CLEAN; 1787 bp->b_flags |= B_AGE; 1788 /* remaining buffers */ 1789 } else if (bp->b_flags & B_DELWRI) 1790 qindex = QUEUE_DIRTY; 1791 else 1792 qindex = QUEUE_CLEAN; 1793 1794 binsfree(bp, qindex); 1795 1796 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 1797 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1798 panic("brelse: not dirty"); 1799 /* unlock */ 1800 BUF_UNLOCK(bp); 1801} 1802 1803/* 1804 * Release a buffer back to the appropriate queue but do not try to free 1805 * it. The buffer is expected to be used again soon. 1806 * 1807 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1808 * biodone() to requeue an async I/O on completion. It is also used when 1809 * known good buffers need to be requeued but we think we may need the data 1810 * again soon. 1811 * 1812 * XXX we should be able to leave the B_RELBUF hint set on completion. 1813 */ 1814void 1815bqrelse(struct buf *bp) 1816{ 1817 int qindex; 1818 1819 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1820 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1821 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1822 1823 if (BUF_LOCKRECURSED(bp)) { 1824 /* do not release to free list */ 1825 BUF_UNLOCK(bp); 1826 return; 1827 } 1828 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1829 1830 if (bp->b_flags & B_MANAGED) { 1831 if (bp->b_flags & B_REMFREE) 1832 bremfreef(bp); 1833 goto out; 1834 } 1835 1836 /* buffers with stale but valid contents */ 1837 if ((bp->b_flags & B_DELWRI) != 0 || (bp->b_vflags & (BV_BKGRDINPROG | 1838 BV_BKGRDERR)) == BV_BKGRDERR) { 1839 BO_LOCK(bp->b_bufobj); 1840 bp->b_vflags &= ~BV_BKGRDERR; 1841 BO_UNLOCK(bp->b_bufobj); 1842 qindex = QUEUE_DIRTY; 1843 } else { 1844 if ((bp->b_flags & B_DELWRI) == 0 && 1845 (bp->b_xflags & BX_VNDIRTY)) 1846 panic("bqrelse: not dirty"); 1847 /* 1848 * BKGRDINPROG can only be set with the buf and bufobj 1849 * locks both held. We tolerate a race to clear it here. 1850 */ 1851 if (buf_vm_page_count_severe() && 1852 (bp->b_vflags & BV_BKGRDINPROG) == 0) { 1853 /* 1854 * We are too low on memory, we have to try to free 1855 * the buffer (most importantly: the wired pages 1856 * making up its backing store) *now*. 1857 */ 1858 brelse(bp); 1859 return; 1860 } 1861 qindex = QUEUE_CLEAN; 1862 } 1863 binsfree(bp, qindex); 1864 1865out: 1866 /* unlock */ 1867 BUF_UNLOCK(bp); 1868} 1869 1870/* Give pages used by the bp back to the VM system (where possible) */ 1871static void 1872vfs_vmio_release(struct buf *bp) 1873{ 1874 vm_object_t obj; 1875 vm_page_t m; 1876 int i; 1877 1878 if ((bp->b_flags & B_UNMAPPED) == 0) { 1879 BUF_CHECK_MAPPED(bp); 1880 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages); 1881 } else 1882 BUF_CHECK_UNMAPPED(bp); 1883 obj = bp->b_bufobj->bo_object; 1884 if (obj != NULL) 1885 VM_OBJECT_WLOCK(obj); 1886 for (i = 0; i < bp->b_npages; i++) { 1887 m = bp->b_pages[i]; 1888 bp->b_pages[i] = NULL; 1889 /* 1890 * In order to keep page LRU ordering consistent, put 1891 * everything on the inactive queue. 1892 */ 1893 vm_page_lock(m); 1894 vm_page_unwire(m, 0); 1895 1896 /* 1897 * Might as well free the page if we can and it has 1898 * no valid data. We also free the page if the 1899 * buffer was used for direct I/O 1900 */ 1901 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid) { 1902 if (m->wire_count == 0 && !vm_page_busied(m)) 1903 vm_page_free(m); 1904 } else if (bp->b_flags & B_DIRECT) 1905 vm_page_try_to_free(m); 1906 else if (buf_vm_page_count_severe()) 1907 vm_page_try_to_cache(m); 1908 vm_page_unlock(m); 1909 } 1910 if (obj != NULL) 1911 VM_OBJECT_WUNLOCK(obj); 1912 1913 if (bp->b_bufsize) { 1914 bufspacewakeup(); 1915 bp->b_bufsize = 0; 1916 } 1917 bp->b_npages = 0; 1918 bp->b_flags &= ~B_VMIO; 1919 if (bp->b_vp) 1920 brelvp(bp); 1921} 1922 1923/* 1924 * Check to see if a block at a particular lbn is available for a clustered 1925 * write. 1926 */ 1927static int 1928vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 1929{ 1930 struct buf *bpa; 1931 int match; 1932 1933 match = 0; 1934 1935 /* If the buf isn't in core skip it */ 1936 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 1937 return (0); 1938 1939 /* If the buf is busy we don't want to wait for it */ 1940 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1941 return (0); 1942 1943 /* Only cluster with valid clusterable delayed write buffers */ 1944 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 1945 (B_DELWRI | B_CLUSTEROK)) 1946 goto done; 1947 1948 if (bpa->b_bufsize != size) 1949 goto done; 1950 1951 /* 1952 * Check to see if it is in the expected place on disk and that the 1953 * block has been mapped. 1954 */ 1955 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 1956 match = 1; 1957done: 1958 BUF_UNLOCK(bpa); 1959 return (match); 1960} 1961 1962/* 1963 * vfs_bio_awrite: 1964 * 1965 * Implement clustered async writes for clearing out B_DELWRI buffers. 1966 * This is much better then the old way of writing only one buffer at 1967 * a time. Note that we may not be presented with the buffers in the 1968 * correct order, so we search for the cluster in both directions. 1969 */ 1970int 1971vfs_bio_awrite(struct buf *bp) 1972{ 1973 struct bufobj *bo; 1974 int i; 1975 int j; 1976 daddr_t lblkno = bp->b_lblkno; 1977 struct vnode *vp = bp->b_vp; 1978 int ncl; 1979 int nwritten; 1980 int size; 1981 int maxcl; 1982 int gbflags; 1983 1984 bo = &vp->v_bufobj; 1985 gbflags = (bp->b_flags & B_UNMAPPED) != 0 ? GB_UNMAPPED : 0; 1986 /* 1987 * right now we support clustered writing only to regular files. If 1988 * we find a clusterable block we could be in the middle of a cluster 1989 * rather then at the beginning. 1990 */ 1991 if ((vp->v_type == VREG) && 1992 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1993 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1994 1995 size = vp->v_mount->mnt_stat.f_iosize; 1996 maxcl = MAXPHYS / size; 1997 1998 BO_RLOCK(bo); 1999 for (i = 1; i < maxcl; i++) 2000 if (vfs_bio_clcheck(vp, size, lblkno + i, 2001 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 2002 break; 2003 2004 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 2005 if (vfs_bio_clcheck(vp, size, lblkno - j, 2006 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 2007 break; 2008 BO_RUNLOCK(bo); 2009 --j; 2010 ncl = i + j; 2011 /* 2012 * this is a possible cluster write 2013 */ 2014 if (ncl != 1) { 2015 BUF_UNLOCK(bp); 2016 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl, 2017 gbflags); 2018 return (nwritten); 2019 } 2020 } 2021 bremfree(bp); 2022 bp->b_flags |= B_ASYNC; 2023 /* 2024 * default (old) behavior, writing out only one block 2025 * 2026 * XXX returns b_bufsize instead of b_bcount for nwritten? 2027 */ 2028 nwritten = bp->b_bufsize; 2029 (void) bwrite(bp); 2030 2031 return (nwritten); 2032} 2033 2034static void 2035setbufkva(struct buf *bp, vm_offset_t addr, int maxsize, int gbflags) 2036{ 2037 2038 KASSERT((bp->b_flags & (B_UNMAPPED | B_KVAALLOC)) == 0 && 2039 bp->b_kvasize == 0, ("call bfreekva(%p)", bp)); 2040 if ((gbflags & GB_UNMAPPED) == 0) { 2041 bp->b_kvabase = (caddr_t)addr; 2042 } else if ((gbflags & GB_KVAALLOC) != 0) { 2043 KASSERT((gbflags & GB_UNMAPPED) != 0, 2044 ("GB_KVAALLOC without GB_UNMAPPED")); 2045 bp->b_kvaalloc = (caddr_t)addr; 2046 bp->b_flags |= B_UNMAPPED | B_KVAALLOC; 2047 atomic_add_long(&unmapped_bufspace, bp->b_kvasize); 2048 } 2049 bp->b_kvasize = maxsize; 2050} 2051 2052/* 2053 * Allocate the buffer KVA and set b_kvasize. Also set b_kvabase if 2054 * needed. 2055 */ 2056static int 2057allocbufkva(struct buf *bp, int maxsize, int gbflags) 2058{ 2059 vm_offset_t addr; 2060 2061 bfreekva(bp); 2062 addr = 0; 2063 2064 if (vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr)) { 2065 /* 2066 * Buffer map is too fragmented. Request the caller 2067 * to defragment the map. 2068 */ 2069 atomic_add_int(&bufdefragcnt, 1); 2070 return (1); 2071 } 2072 setbufkva(bp, addr, maxsize, gbflags); 2073 atomic_add_long(&bufspace, bp->b_kvasize); 2074 return (0); 2075} 2076 2077/* 2078 * Ask the bufdaemon for help, or act as bufdaemon itself, when a 2079 * locked vnode is supplied. 2080 */ 2081static void 2082getnewbuf_bufd_help(struct vnode *vp, int gbflags, int slpflag, int slptimeo, 2083 int defrag) 2084{ 2085 struct thread *td; 2086 char *waitmsg; 2087 int error, fl, flags, norunbuf; 2088 2089 mtx_assert(&bqclean, MA_OWNED); 2090 2091 if (defrag) { 2092 flags = VFS_BIO_NEED_BUFSPACE; 2093 waitmsg = "nbufkv"; 2094 } else if (bufspace >= hibufspace) { 2095 waitmsg = "nbufbs"; 2096 flags = VFS_BIO_NEED_BUFSPACE; 2097 } else { 2098 waitmsg = "newbuf"; 2099 flags = VFS_BIO_NEED_ANY; 2100 } 2101 atomic_set_int(&needsbuffer, flags); 2102 mtx_unlock(&bqclean); 2103 2104 bd_speedup(); /* heeeelp */ 2105 if ((gbflags & GB_NOWAIT_BD) != 0) 2106 return; 2107 2108 td = curthread; 2109 rw_wlock(&nblock); 2110 while ((needsbuffer & flags) != 0) { 2111 if (vp != NULL && vp->v_type != VCHR && 2112 (td->td_pflags & TDP_BUFNEED) == 0) { 2113 rw_wunlock(&nblock); 2114 /* 2115 * getblk() is called with a vnode locked, and 2116 * some majority of the dirty buffers may as 2117 * well belong to the vnode. Flushing the 2118 * buffers there would make a progress that 2119 * cannot be achieved by the buf_daemon, that 2120 * cannot lock the vnode. 2121 */ 2122 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) | 2123 (td->td_pflags & TDP_NORUNNINGBUF); 2124 2125 /* 2126 * Play bufdaemon. The getnewbuf() function 2127 * may be called while the thread owns lock 2128 * for another dirty buffer for the same 2129 * vnode, which makes it impossible to use 2130 * VOP_FSYNC() there, due to the buffer lock 2131 * recursion. 2132 */ 2133 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF; 2134 fl = buf_flush(vp, flushbufqtarget); 2135 td->td_pflags &= norunbuf; 2136 rw_wlock(&nblock); 2137 if (fl != 0) 2138 continue; 2139 if ((needsbuffer & flags) == 0) 2140 break; 2141 } 2142 error = rw_sleep(__DEVOLATILE(void *, &needsbuffer), &nblock, 2143 (PRIBIO + 4) | slpflag, waitmsg, slptimeo); 2144 if (error != 0) 2145 break; 2146 } 2147 rw_wunlock(&nblock); 2148} 2149 2150static void 2151getnewbuf_reuse_bp(struct buf *bp, int qindex) 2152{ 2153 2154 CTR6(KTR_BUF, "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d " 2155 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags, 2156 bp->b_kvasize, bp->b_bufsize, qindex); 2157 mtx_assert(&bqclean, MA_NOTOWNED); 2158 2159 /* 2160 * Note: we no longer distinguish between VMIO and non-VMIO 2161 * buffers. 2162 */ 2163 KASSERT((bp->b_flags & B_DELWRI) == 0, 2164 ("delwri buffer %p found in queue %d", bp, qindex)); 2165 2166 if (qindex == QUEUE_CLEAN) { 2167 if (bp->b_flags & B_VMIO) { 2168 bp->b_flags &= ~B_ASYNC; 2169 vfs_vmio_release(bp); 2170 } 2171 if (bp->b_vp != NULL) 2172 brelvp(bp); 2173 } 2174 2175 /* 2176 * Get the rest of the buffer freed up. b_kva* is still valid 2177 * after this operation. 2178 */ 2179 2180 if (bp->b_rcred != NOCRED) { 2181 crfree(bp->b_rcred); 2182 bp->b_rcred = NOCRED; 2183 } 2184 if (bp->b_wcred != NOCRED) { 2185 crfree(bp->b_wcred); 2186 bp->b_wcred = NOCRED; 2187 } 2188 if (!LIST_EMPTY(&bp->b_dep)) 2189 buf_deallocate(bp); 2190 if (bp->b_vflags & BV_BKGRDINPROG) 2191 panic("losing buffer 3"); 2192 KASSERT(bp->b_vp == NULL, ("bp: %p still has vnode %p. qindex: %d", 2193 bp, bp->b_vp, qindex)); 2194 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 2195 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags)); 2196 2197 if (bp->b_bufsize) 2198 allocbuf(bp, 0); 2199 2200 bp->b_flags &= B_UNMAPPED | B_KVAALLOC; 2201 bp->b_ioflags = 0; 2202 bp->b_xflags = 0; 2203 KASSERT((bp->b_flags & B_INFREECNT) == 0, 2204 ("buf %p still counted as free?", bp)); 2205 bp->b_vflags = 0; 2206 bp->b_vp = NULL; 2207 bp->b_blkno = bp->b_lblkno = 0; 2208 bp->b_offset = NOOFFSET; 2209 bp->b_iodone = 0; 2210 bp->b_error = 0; 2211 bp->b_resid = 0; 2212 bp->b_bcount = 0; 2213 bp->b_npages = 0; 2214 bp->b_dirtyoff = bp->b_dirtyend = 0; 2215 bp->b_bufobj = NULL; 2216 bp->b_pin_count = 0; 2217 bp->b_fsprivate1 = NULL; 2218 bp->b_fsprivate2 = NULL; 2219 bp->b_fsprivate3 = NULL; 2220 2221 LIST_INIT(&bp->b_dep); 2222} 2223 2224static int flushingbufs; 2225 2226static struct buf * 2227getnewbuf_scan(int maxsize, int defrag, int unmapped, int metadata) 2228{ 2229 struct buf *bp, *nbp; 2230 int nqindex, qindex, pass; 2231 2232 KASSERT(!unmapped || !defrag, ("both unmapped and defrag")); 2233 2234 pass = 1; 2235restart: 2236 atomic_add_int(&getnewbufrestarts, 1); 2237 2238 /* 2239 * Setup for scan. If we do not have enough free buffers, 2240 * we setup a degenerate case that immediately fails. Note 2241 * that if we are specially marked process, we are allowed to 2242 * dip into our reserves. 2243 * 2244 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 2245 * for the allocation of the mapped buffer. For unmapped, the 2246 * easiest is to start with EMPTY outright. 2247 * 2248 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 2249 * However, there are a number of cases (defragging, reusing, ...) 2250 * where we cannot backup. 2251 */ 2252 nbp = NULL; 2253 mtx_lock(&bqclean); 2254 if (!defrag && unmapped) { 2255 nqindex = QUEUE_EMPTY; 2256 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 2257 } 2258 if (nbp == NULL) { 2259 nqindex = QUEUE_EMPTYKVA; 2260 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 2261 } 2262 2263 /* 2264 * If no EMPTYKVA buffers and we are either defragging or 2265 * reusing, locate a CLEAN buffer to free or reuse. If 2266 * bufspace useage is low skip this step so we can allocate a 2267 * new buffer. 2268 */ 2269 if (nbp == NULL && (defrag || bufspace >= lobufspace)) { 2270 nqindex = QUEUE_CLEAN; 2271 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2272 } 2273 2274 /* 2275 * If we could not find or were not allowed to reuse a CLEAN 2276 * buffer, check to see if it is ok to use an EMPTY buffer. 2277 * We can only use an EMPTY buffer if allocating its KVA would 2278 * not otherwise run us out of buffer space. No KVA is needed 2279 * for the unmapped allocation. 2280 */ 2281 if (nbp == NULL && defrag == 0 && (bufspace + maxsize < hibufspace || 2282 metadata)) { 2283 nqindex = QUEUE_EMPTY; 2284 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 2285 } 2286 2287 /* 2288 * All available buffers might be clean, retry ignoring the 2289 * lobufspace as the last resort. 2290 */ 2291 if (nbp == NULL && !TAILQ_EMPTY(&bufqueues[QUEUE_CLEAN])) { 2292 nqindex = QUEUE_CLEAN; 2293 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2294 } 2295 2296 /* 2297 * Run scan, possibly freeing data and/or kva mappings on the fly 2298 * depending. 2299 */ 2300 while ((bp = nbp) != NULL) { 2301 qindex = nqindex; 2302 2303 /* 2304 * Calculate next bp (we can only use it if we do not 2305 * block or do other fancy things). 2306 */ 2307 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 2308 switch (qindex) { 2309 case QUEUE_EMPTY: 2310 nqindex = QUEUE_EMPTYKVA; 2311 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 2312 if (nbp != NULL) 2313 break; 2314 /* FALLTHROUGH */ 2315 case QUEUE_EMPTYKVA: 2316 nqindex = QUEUE_CLEAN; 2317 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2318 if (nbp != NULL) 2319 break; 2320 /* FALLTHROUGH */ 2321 case QUEUE_CLEAN: 2322 if (metadata && pass == 1) { 2323 pass = 2; 2324 nqindex = QUEUE_EMPTY; 2325 nbp = TAILQ_FIRST( 2326 &bufqueues[QUEUE_EMPTY]); 2327 } 2328 /* 2329 * nbp is NULL. 2330 */ 2331 break; 2332 } 2333 } 2334 /* 2335 * If we are defragging then we need a buffer with 2336 * b_kvasize != 0. XXX this situation should no longer 2337 * occur, if defrag is non-zero the buffer's b_kvasize 2338 * should also be non-zero at this point. XXX 2339 */ 2340 if (defrag && bp->b_kvasize == 0) { 2341 printf("Warning: defrag empty buffer %p\n", bp); 2342 continue; 2343 } 2344 2345 /* 2346 * Start freeing the bp. This is somewhat involved. nbp 2347 * remains valid only for QUEUE_EMPTY[KVA] bp's. 2348 */ 2349 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2350 continue; 2351 /* 2352 * BKGRDINPROG can only be set with the buf and bufobj 2353 * locks both held. We tolerate a race to clear it here. 2354 */ 2355 if (bp->b_vflags & BV_BKGRDINPROG) { 2356 BUF_UNLOCK(bp); 2357 continue; 2358 } 2359 2360 /* 2361 * Requeue the background write buffer with error. 2362 */ 2363 if ((bp->b_vflags & BV_BKGRDERR) != 0) { 2364 bremfreel(bp); 2365 mtx_unlock(&bqclean); 2366 bqrelse(bp); 2367 continue; 2368 } 2369 2370 KASSERT(bp->b_qindex == qindex, 2371 ("getnewbuf: inconsistent queue %d bp %p", qindex, bp)); 2372 2373 bremfreel(bp); 2374 mtx_unlock(&bqclean); 2375 /* 2376 * NOTE: nbp is now entirely invalid. We can only restart 2377 * the scan from this point on. 2378 */ 2379 2380 getnewbuf_reuse_bp(bp, qindex); 2381 mtx_assert(&bqclean, MA_NOTOWNED); 2382 2383 /* 2384 * If we are defragging then free the buffer. 2385 */ 2386 if (defrag) { 2387 bp->b_flags |= B_INVAL; 2388 bfreekva(bp); 2389 brelse(bp); 2390 defrag = 0; 2391 goto restart; 2392 } 2393 2394 /* 2395 * Notify any waiters for the buffer lock about 2396 * identity change by freeing the buffer. 2397 */ 2398 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp)) { 2399 bp->b_flags |= B_INVAL; 2400 bfreekva(bp); 2401 brelse(bp); 2402 goto restart; 2403 } 2404 2405 if (metadata) 2406 break; 2407 2408 /* 2409 * If we are overcomitted then recover the buffer and its 2410 * KVM space. This occurs in rare situations when multiple 2411 * processes are blocked in getnewbuf() or allocbuf(). 2412 */ 2413 if (bufspace >= hibufspace) 2414 flushingbufs = 1; 2415 if (flushingbufs && bp->b_kvasize != 0) { 2416 bp->b_flags |= B_INVAL; 2417 bfreekva(bp); 2418 brelse(bp); 2419 goto restart; 2420 } 2421 if (bufspace < lobufspace) 2422 flushingbufs = 0; 2423 break; 2424 } 2425 return (bp); 2426} 2427 2428/* 2429 * getnewbuf: 2430 * 2431 * Find and initialize a new buffer header, freeing up existing buffers 2432 * in the bufqueues as necessary. The new buffer is returned locked. 2433 * 2434 * Important: B_INVAL is not set. If the caller wishes to throw the 2435 * buffer away, the caller must set B_INVAL prior to calling brelse(). 2436 * 2437 * We block if: 2438 * We have insufficient buffer headers 2439 * We have insufficient buffer space 2440 * buffer_arena is too fragmented ( space reservation fails ) 2441 * If we have to flush dirty buffers ( but we try to avoid this ) 2442 */ 2443static struct buf * 2444getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int size, int maxsize, 2445 int gbflags) 2446{ 2447 struct buf *bp; 2448 int defrag, metadata; 2449 2450 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 2451 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 2452 if (!unmapped_buf_allowed) 2453 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC); 2454 2455 defrag = 0; 2456 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 || 2457 vp->v_type == VCHR) 2458 metadata = 1; 2459 else 2460 metadata = 0; 2461 /* 2462 * We can't afford to block since we might be holding a vnode lock, 2463 * which may prevent system daemons from running. We deal with 2464 * low-memory situations by proactively returning memory and running 2465 * async I/O rather then sync I/O. 2466 */ 2467 atomic_add_int(&getnewbufcalls, 1); 2468 atomic_subtract_int(&getnewbufrestarts, 1); 2469restart: 2470 bp = getnewbuf_scan(maxsize, defrag, (gbflags & (GB_UNMAPPED | 2471 GB_KVAALLOC)) == GB_UNMAPPED, metadata); 2472 if (bp != NULL) 2473 defrag = 0; 2474 2475 /* 2476 * If we exhausted our list, sleep as appropriate. We may have to 2477 * wakeup various daemons and write out some dirty buffers. 2478 * 2479 * Generally we are sleeping due to insufficient buffer space. 2480 */ 2481 if (bp == NULL) { 2482 mtx_assert(&bqclean, MA_OWNED); 2483 getnewbuf_bufd_help(vp, gbflags, slpflag, slptimeo, defrag); 2484 mtx_assert(&bqclean, MA_NOTOWNED); 2485 } else if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == GB_UNMAPPED) { 2486 mtx_assert(&bqclean, MA_NOTOWNED); 2487 2488 bfreekva(bp); 2489 bp->b_flags |= B_UNMAPPED; 2490 bp->b_kvabase = bp->b_data = unmapped_buf; 2491 bp->b_kvasize = maxsize; 2492 atomic_add_long(&bufspace, bp->b_kvasize); 2493 atomic_add_long(&unmapped_bufspace, bp->b_kvasize); 2494 atomic_add_int(&bufreusecnt, 1); 2495 } else { 2496 mtx_assert(&bqclean, MA_NOTOWNED); 2497 2498 /* 2499 * We finally have a valid bp. We aren't quite out of the 2500 * woods, we still have to reserve kva space. In order 2501 * to keep fragmentation sane we only allocate kva in 2502 * BKVASIZE chunks. 2503 */ 2504 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2505 2506 if (maxsize != bp->b_kvasize || (bp->b_flags & (B_UNMAPPED | 2507 B_KVAALLOC)) == B_UNMAPPED) { 2508 if (allocbufkva(bp, maxsize, gbflags)) { 2509 defrag = 1; 2510 bp->b_flags |= B_INVAL; 2511 brelse(bp); 2512 goto restart; 2513 } 2514 atomic_add_int(&bufreusecnt, 1); 2515 } else if ((bp->b_flags & B_KVAALLOC) != 0 && 2516 (gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == 0) { 2517 /* 2518 * If the reused buffer has KVA allocated, 2519 * reassign b_kvaalloc to b_kvabase. 2520 */ 2521 bp->b_kvabase = bp->b_kvaalloc; 2522 bp->b_flags &= ~B_KVAALLOC; 2523 atomic_subtract_long(&unmapped_bufspace, 2524 bp->b_kvasize); 2525 atomic_add_int(&bufreusecnt, 1); 2526 } else if ((bp->b_flags & (B_UNMAPPED | B_KVAALLOC)) == 0 && 2527 (gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == (GB_UNMAPPED | 2528 GB_KVAALLOC)) { 2529 /* 2530 * The case of reused buffer already have KVA 2531 * mapped, but the request is for unmapped 2532 * buffer with KVA allocated. 2533 */ 2534 bp->b_kvaalloc = bp->b_kvabase; 2535 bp->b_data = bp->b_kvabase = unmapped_buf; 2536 bp->b_flags |= B_UNMAPPED | B_KVAALLOC; 2537 atomic_add_long(&unmapped_bufspace, 2538 bp->b_kvasize); 2539 atomic_add_int(&bufreusecnt, 1); 2540 } 2541 if ((gbflags & GB_UNMAPPED) == 0) { 2542 bp->b_saveaddr = bp->b_kvabase; 2543 bp->b_data = bp->b_saveaddr; 2544 bp->b_flags &= ~B_UNMAPPED; 2545 BUF_CHECK_MAPPED(bp); 2546 } 2547 } 2548 return (bp); 2549} 2550 2551/* 2552 * buf_daemon: 2553 * 2554 * buffer flushing daemon. Buffers are normally flushed by the 2555 * update daemon but if it cannot keep up this process starts to 2556 * take the load in an attempt to prevent getnewbuf() from blocking. 2557 */ 2558 2559static struct kproc_desc buf_kp = { 2560 "bufdaemon", 2561 buf_daemon, 2562 &bufdaemonproc 2563}; 2564SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 2565 2566static int 2567buf_flush(struct vnode *vp, int target) 2568{ 2569 int flushed; 2570 2571 flushed = flushbufqueues(vp, target, 0); 2572 if (flushed == 0) { 2573 /* 2574 * Could not find any buffers without rollback 2575 * dependencies, so just write the first one 2576 * in the hopes of eventually making progress. 2577 */ 2578 if (vp != NULL && target > 2) 2579 target /= 2; 2580 flushbufqueues(vp, target, 1); 2581 } 2582 return (flushed); 2583} 2584 2585static void 2586buf_daemon() 2587{ 2588 int lodirty; 2589 2590 /* 2591 * This process needs to be suspended prior to shutdown sync. 2592 */ 2593 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2594 SHUTDOWN_PRI_LAST); 2595 2596 /* 2597 * This process is allowed to take the buffer cache to the limit 2598 */ 2599 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 2600 mtx_lock(&bdlock); 2601 for (;;) { 2602 bd_request = 0; 2603 mtx_unlock(&bdlock); 2604 2605 kproc_suspend_check(bufdaemonproc); 2606 lodirty = lodirtybuffers; 2607 if (bd_speedupreq) { 2608 lodirty = numdirtybuffers / 2; 2609 bd_speedupreq = 0; 2610 } 2611 /* 2612 * Do the flush. Limit the amount of in-transit I/O we 2613 * allow to build up, otherwise we would completely saturate 2614 * the I/O system. 2615 */ 2616 while (numdirtybuffers > lodirty) { 2617 if (buf_flush(NULL, numdirtybuffers - lodirty) == 0) 2618 break; 2619 kern_yield(PRI_USER); 2620 } 2621 2622 /* 2623 * Only clear bd_request if we have reached our low water 2624 * mark. The buf_daemon normally waits 1 second and 2625 * then incrementally flushes any dirty buffers that have 2626 * built up, within reason. 2627 * 2628 * If we were unable to hit our low water mark and couldn't 2629 * find any flushable buffers, we sleep for a short period 2630 * to avoid endless loops on unlockable buffers. 2631 */ 2632 mtx_lock(&bdlock); 2633 if (numdirtybuffers <= lodirtybuffers) { 2634 /* 2635 * We reached our low water mark, reset the 2636 * request and sleep until we are needed again. 2637 * The sleep is just so the suspend code works. 2638 */ 2639 bd_request = 0; 2640 /* 2641 * Do an extra wakeup in case dirty threshold 2642 * changed via sysctl and the explicit transition 2643 * out of shortfall was missed. 2644 */ 2645 bdirtywakeup(); 2646 if (runningbufspace <= lorunningspace) 2647 runningwakeup(); 2648 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 2649 } else { 2650 /* 2651 * We couldn't find any flushable dirty buffers but 2652 * still have too many dirty buffers, we 2653 * have to sleep and try again. (rare) 2654 */ 2655 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 2656 } 2657 } 2658} 2659 2660/* 2661 * flushbufqueues: 2662 * 2663 * Try to flush a buffer in the dirty queue. We must be careful to 2664 * free up B_INVAL buffers instead of write them, which NFS is 2665 * particularly sensitive to. 2666 */ 2667static int flushwithdeps = 0; 2668SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 2669 0, "Number of buffers flushed with dependecies that require rollbacks"); 2670 2671static int 2672flushbufqueues(struct vnode *lvp, int target, int flushdeps) 2673{ 2674 struct buf *sentinel; 2675 struct vnode *vp; 2676 struct mount *mp; 2677 struct buf *bp; 2678 int hasdeps; 2679 int flushed; 2680 int queue; 2681 int error; 2682 bool unlock; 2683 2684 flushed = 0; 2685 queue = QUEUE_DIRTY; 2686 bp = NULL; 2687 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 2688 sentinel->b_qindex = QUEUE_SENTINEL; 2689 mtx_lock(&bqdirty); 2690 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist); 2691 mtx_unlock(&bqdirty); 2692 while (flushed != target) { 2693 maybe_yield(); 2694 mtx_lock(&bqdirty); 2695 bp = TAILQ_NEXT(sentinel, b_freelist); 2696 if (bp != NULL) { 2697 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2698 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel, 2699 b_freelist); 2700 } else { 2701 mtx_unlock(&bqdirty); 2702 break; 2703 } 2704 /* 2705 * Skip sentinels inserted by other invocations of the 2706 * flushbufqueues(), taking care to not reorder them. 2707 * 2708 * Only flush the buffers that belong to the 2709 * vnode locked by the curthread. 2710 */ 2711 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL && 2712 bp->b_vp != lvp)) { 2713 mtx_unlock(&bqdirty); 2714 continue; 2715 } 2716 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL); 2717 mtx_unlock(&bqdirty); 2718 if (error != 0) 2719 continue; 2720 if (bp->b_pin_count > 0) { 2721 BUF_UNLOCK(bp); 2722 continue; 2723 } 2724 /* 2725 * BKGRDINPROG can only be set with the buf and bufobj 2726 * locks both held. We tolerate a race to clear it here. 2727 */ 2728 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 2729 (bp->b_flags & B_DELWRI) == 0) { 2730 BUF_UNLOCK(bp); 2731 continue; 2732 } 2733 if (bp->b_flags & B_INVAL) { 2734 bremfreef(bp); 2735 brelse(bp); 2736 flushed++; 2737 continue; 2738 } 2739 2740 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 2741 if (flushdeps == 0) { 2742 BUF_UNLOCK(bp); 2743 continue; 2744 } 2745 hasdeps = 1; 2746 } else 2747 hasdeps = 0; 2748 /* 2749 * We must hold the lock on a vnode before writing 2750 * one of its buffers. Otherwise we may confuse, or 2751 * in the case of a snapshot vnode, deadlock the 2752 * system. 2753 * 2754 * The lock order here is the reverse of the normal 2755 * of vnode followed by buf lock. This is ok because 2756 * the NOWAIT will prevent deadlock. 2757 */ 2758 vp = bp->b_vp; 2759 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 2760 BUF_UNLOCK(bp); 2761 continue; 2762 } 2763 if (lvp == NULL) { 2764 unlock = true; 2765 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT); 2766 } else { 2767 ASSERT_VOP_LOCKED(vp, "getbuf"); 2768 unlock = false; 2769 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 : 2770 vn_lock(vp, LK_TRYUPGRADE); 2771 } 2772 if (error == 0) { 2773 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 2774 bp, bp->b_vp, bp->b_flags); 2775 if (curproc == bufdaemonproc) { 2776 vfs_bio_awrite(bp); 2777 } else { 2778 bremfree(bp); 2779 bwrite(bp); 2780 notbufdflushes++; 2781 } 2782 vn_finished_write(mp); 2783 if (unlock) 2784 VOP_UNLOCK(vp, 0); 2785 flushwithdeps += hasdeps; 2786 flushed++; 2787 2788 /* 2789 * Sleeping on runningbufspace while holding 2790 * vnode lock leads to deadlock. 2791 */ 2792 if (curproc == bufdaemonproc && 2793 runningbufspace > hirunningspace) 2794 waitrunningbufspace(); 2795 continue; 2796 } 2797 vn_finished_write(mp); 2798 BUF_UNLOCK(bp); 2799 } 2800 mtx_lock(&bqdirty); 2801 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2802 mtx_unlock(&bqdirty); 2803 free(sentinel, M_TEMP); 2804 return (flushed); 2805} 2806 2807/* 2808 * Check to see if a block is currently memory resident. 2809 */ 2810struct buf * 2811incore(struct bufobj *bo, daddr_t blkno) 2812{ 2813 struct buf *bp; 2814 2815 BO_RLOCK(bo); 2816 bp = gbincore(bo, blkno); 2817 BO_RUNLOCK(bo); 2818 return (bp); 2819} 2820 2821/* 2822 * Returns true if no I/O is needed to access the 2823 * associated VM object. This is like incore except 2824 * it also hunts around in the VM system for the data. 2825 */ 2826 2827static int 2828inmem(struct vnode * vp, daddr_t blkno) 2829{ 2830 vm_object_t obj; 2831 vm_offset_t toff, tinc, size; 2832 vm_page_t m; 2833 vm_ooffset_t off; 2834 2835 ASSERT_VOP_LOCKED(vp, "inmem"); 2836 2837 if (incore(&vp->v_bufobj, blkno)) 2838 return 1; 2839 if (vp->v_mount == NULL) 2840 return 0; 2841 obj = vp->v_object; 2842 if (obj == NULL) 2843 return (0); 2844 2845 size = PAGE_SIZE; 2846 if (size > vp->v_mount->mnt_stat.f_iosize) 2847 size = vp->v_mount->mnt_stat.f_iosize; 2848 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2849 2850 VM_OBJECT_RLOCK(obj); 2851 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2852 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2853 if (!m) 2854 goto notinmem; 2855 tinc = size; 2856 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2857 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2858 if (vm_page_is_valid(m, 2859 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2860 goto notinmem; 2861 } 2862 VM_OBJECT_RUNLOCK(obj); 2863 return 1; 2864 2865notinmem: 2866 VM_OBJECT_RUNLOCK(obj); 2867 return (0); 2868} 2869 2870/* 2871 * Set the dirty range for a buffer based on the status of the dirty 2872 * bits in the pages comprising the buffer. The range is limited 2873 * to the size of the buffer. 2874 * 2875 * Tell the VM system that the pages associated with this buffer 2876 * are clean. This is used for delayed writes where the data is 2877 * going to go to disk eventually without additional VM intevention. 2878 * 2879 * Note that while we only really need to clean through to b_bcount, we 2880 * just go ahead and clean through to b_bufsize. 2881 */ 2882static void 2883vfs_clean_pages_dirty_buf(struct buf *bp) 2884{ 2885 vm_ooffset_t foff, noff, eoff; 2886 vm_page_t m; 2887 int i; 2888 2889 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 2890 return; 2891 2892 foff = bp->b_offset; 2893 KASSERT(bp->b_offset != NOOFFSET, 2894 ("vfs_clean_pages_dirty_buf: no buffer offset")); 2895 2896 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 2897 vfs_drain_busy_pages(bp); 2898 vfs_setdirty_locked_object(bp); 2899 for (i = 0; i < bp->b_npages; i++) { 2900 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2901 eoff = noff; 2902 if (eoff > bp->b_offset + bp->b_bufsize) 2903 eoff = bp->b_offset + bp->b_bufsize; 2904 m = bp->b_pages[i]; 2905 vfs_page_set_validclean(bp, foff, m); 2906 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 2907 foff = noff; 2908 } 2909 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 2910} 2911 2912static void 2913vfs_setdirty_locked_object(struct buf *bp) 2914{ 2915 vm_object_t object; 2916 int i; 2917 2918 object = bp->b_bufobj->bo_object; 2919 VM_OBJECT_ASSERT_WLOCKED(object); 2920 2921 /* 2922 * We qualify the scan for modified pages on whether the 2923 * object has been flushed yet. 2924 */ 2925 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) { 2926 vm_offset_t boffset; 2927 vm_offset_t eoffset; 2928 2929 /* 2930 * test the pages to see if they have been modified directly 2931 * by users through the VM system. 2932 */ 2933 for (i = 0; i < bp->b_npages; i++) 2934 vm_page_test_dirty(bp->b_pages[i]); 2935 2936 /* 2937 * Calculate the encompassing dirty range, boffset and eoffset, 2938 * (eoffset - boffset) bytes. 2939 */ 2940 2941 for (i = 0; i < bp->b_npages; i++) { 2942 if (bp->b_pages[i]->dirty) 2943 break; 2944 } 2945 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2946 2947 for (i = bp->b_npages - 1; i >= 0; --i) { 2948 if (bp->b_pages[i]->dirty) { 2949 break; 2950 } 2951 } 2952 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2953 2954 /* 2955 * Fit it to the buffer. 2956 */ 2957 2958 if (eoffset > bp->b_bcount) 2959 eoffset = bp->b_bcount; 2960 2961 /* 2962 * If we have a good dirty range, merge with the existing 2963 * dirty range. 2964 */ 2965 2966 if (boffset < eoffset) { 2967 if (bp->b_dirtyoff > boffset) 2968 bp->b_dirtyoff = boffset; 2969 if (bp->b_dirtyend < eoffset) 2970 bp->b_dirtyend = eoffset; 2971 } 2972 } 2973} 2974 2975/* 2976 * Allocate the KVA mapping for an existing buffer. It handles the 2977 * cases of both B_UNMAPPED buffer, and buffer with the preallocated 2978 * KVA which is not mapped (B_KVAALLOC). 2979 */ 2980static void 2981bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags) 2982{ 2983 struct buf *scratch_bp; 2984 int bsize, maxsize, need_mapping, need_kva; 2985 off_t offset; 2986 2987 need_mapping = (bp->b_flags & B_UNMAPPED) != 0 && 2988 (gbflags & GB_UNMAPPED) == 0; 2989 need_kva = (bp->b_flags & (B_KVAALLOC | B_UNMAPPED)) == B_UNMAPPED && 2990 (gbflags & GB_KVAALLOC) != 0; 2991 if (!need_mapping && !need_kva) 2992 return; 2993 2994 BUF_CHECK_UNMAPPED(bp); 2995 2996 if (need_mapping && (bp->b_flags & B_KVAALLOC) != 0) { 2997 /* 2998 * Buffer is not mapped, but the KVA was already 2999 * reserved at the time of the instantiation. Use the 3000 * allocated space. 3001 */ 3002 bp->b_flags &= ~B_KVAALLOC; 3003 KASSERT(bp->b_kvaalloc != 0, ("kvaalloc == 0")); 3004 bp->b_kvabase = bp->b_kvaalloc; 3005 atomic_subtract_long(&unmapped_bufspace, bp->b_kvasize); 3006 goto has_addr; 3007 } 3008 3009 /* 3010 * Calculate the amount of the address space we would reserve 3011 * if the buffer was mapped. 3012 */ 3013 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize; 3014 offset = blkno * bsize; 3015 maxsize = size + (offset & PAGE_MASK); 3016 maxsize = imax(maxsize, bsize); 3017 3018mapping_loop: 3019 if (allocbufkva(bp, maxsize, gbflags)) { 3020 /* 3021 * Request defragmentation. getnewbuf() returns us the 3022 * allocated space by the scratch buffer KVA. 3023 */ 3024 scratch_bp = getnewbuf(bp->b_vp, 0, 0, size, maxsize, gbflags | 3025 (GB_UNMAPPED | GB_KVAALLOC)); 3026 if (scratch_bp == NULL) { 3027 if ((gbflags & GB_NOWAIT_BD) != 0) { 3028 /* 3029 * XXXKIB: defragmentation cannot 3030 * succeed, not sure what else to do. 3031 */ 3032 panic("GB_NOWAIT_BD and B_UNMAPPED %p", bp); 3033 } 3034 atomic_add_int(&mappingrestarts, 1); 3035 goto mapping_loop; 3036 } 3037 KASSERT((scratch_bp->b_flags & B_KVAALLOC) != 0, 3038 ("scratch bp !B_KVAALLOC %p", scratch_bp)); 3039 setbufkva(bp, (vm_offset_t)scratch_bp->b_kvaalloc, 3040 scratch_bp->b_kvasize, gbflags); 3041 3042 /* Get rid of the scratch buffer. */ 3043 scratch_bp->b_kvasize = 0; 3044 scratch_bp->b_flags |= B_INVAL; 3045 scratch_bp->b_flags &= ~(B_UNMAPPED | B_KVAALLOC); 3046 brelse(scratch_bp); 3047 } 3048 if (!need_mapping) 3049 return; 3050 3051has_addr: 3052 bp->b_saveaddr = bp->b_kvabase; 3053 bp->b_data = bp->b_saveaddr; /* b_offset is handled by bpmap_qenter */ 3054 bp->b_flags &= ~B_UNMAPPED; 3055 BUF_CHECK_MAPPED(bp); 3056 bpmap_qenter(bp); 3057} 3058 3059/* 3060 * getblk: 3061 * 3062 * Get a block given a specified block and offset into a file/device. 3063 * The buffers B_DONE bit will be cleared on return, making it almost 3064 * ready for an I/O initiation. B_INVAL may or may not be set on 3065 * return. The caller should clear B_INVAL prior to initiating a 3066 * READ. 3067 * 3068 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 3069 * an existing buffer. 3070 * 3071 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 3072 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 3073 * and then cleared based on the backing VM. If the previous buffer is 3074 * non-0-sized but invalid, B_CACHE will be cleared. 3075 * 3076 * If getblk() must create a new buffer, the new buffer is returned with 3077 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 3078 * case it is returned with B_INVAL clear and B_CACHE set based on the 3079 * backing VM. 3080 * 3081 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 3082 * B_CACHE bit is clear. 3083 * 3084 * What this means, basically, is that the caller should use B_CACHE to 3085 * determine whether the buffer is fully valid or not and should clear 3086 * B_INVAL prior to issuing a read. If the caller intends to validate 3087 * the buffer by loading its data area with something, the caller needs 3088 * to clear B_INVAL. If the caller does this without issuing an I/O, 3089 * the caller should set B_CACHE ( as an optimization ), else the caller 3090 * should issue the I/O and biodone() will set B_CACHE if the I/O was 3091 * a write attempt or if it was a successful read. If the caller 3092 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 3093 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 3094 */ 3095struct buf * 3096getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3097 int flags) 3098{ 3099 struct buf *bp; 3100 struct bufobj *bo; 3101 int bsize, error, maxsize, vmio; 3102 off_t offset; 3103 3104 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 3105 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3106 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3107 ASSERT_VOP_LOCKED(vp, "getblk"); 3108 if (size > MAXBCACHEBUF) 3109 panic("getblk: size(%d) > MAXBCACHEBUF(%d)\n", size, 3110 MAXBCACHEBUF); 3111 if (!unmapped_buf_allowed) 3112 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3113 3114 bo = &vp->v_bufobj; 3115loop: 3116 BO_RLOCK(bo); 3117 bp = gbincore(bo, blkno); 3118 if (bp != NULL) { 3119 int lockflags; 3120 /* 3121 * Buffer is in-core. If the buffer is not busy nor managed, 3122 * it must be on a queue. 3123 */ 3124 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 3125 3126 if (flags & GB_LOCK_NOWAIT) 3127 lockflags |= LK_NOWAIT; 3128 3129 error = BUF_TIMELOCK(bp, lockflags, 3130 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo); 3131 3132 /* 3133 * If we slept and got the lock we have to restart in case 3134 * the buffer changed identities. 3135 */ 3136 if (error == ENOLCK) 3137 goto loop; 3138 /* We timed out or were interrupted. */ 3139 else if (error) 3140 return (NULL); 3141 /* If recursed, assume caller knows the rules. */ 3142 else if (BUF_LOCKRECURSED(bp)) 3143 goto end; 3144 3145 /* 3146 * The buffer is locked. B_CACHE is cleared if the buffer is 3147 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 3148 * and for a VMIO buffer B_CACHE is adjusted according to the 3149 * backing VM cache. 3150 */ 3151 if (bp->b_flags & B_INVAL) 3152 bp->b_flags &= ~B_CACHE; 3153 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 3154 bp->b_flags |= B_CACHE; 3155 if (bp->b_flags & B_MANAGED) 3156 MPASS(bp->b_qindex == QUEUE_NONE); 3157 else 3158 bremfree(bp); 3159 3160 /* 3161 * check for size inconsistencies for non-VMIO case. 3162 */ 3163 if (bp->b_bcount != size) { 3164 if ((bp->b_flags & B_VMIO) == 0 || 3165 (size > bp->b_kvasize)) { 3166 if (bp->b_flags & B_DELWRI) { 3167 /* 3168 * If buffer is pinned and caller does 3169 * not want sleep waiting for it to be 3170 * unpinned, bail out 3171 * */ 3172 if (bp->b_pin_count > 0) { 3173 if (flags & GB_LOCK_NOWAIT) { 3174 bqrelse(bp); 3175 return (NULL); 3176 } else { 3177 bunpin_wait(bp); 3178 } 3179 } 3180 bp->b_flags |= B_NOCACHE; 3181 bwrite(bp); 3182 } else { 3183 if (LIST_EMPTY(&bp->b_dep)) { 3184 bp->b_flags |= B_RELBUF; 3185 brelse(bp); 3186 } else { 3187 bp->b_flags |= B_NOCACHE; 3188 bwrite(bp); 3189 } 3190 } 3191 goto loop; 3192 } 3193 } 3194 3195 /* 3196 * Handle the case of unmapped buffer which should 3197 * become mapped, or the buffer for which KVA 3198 * reservation is requested. 3199 */ 3200 bp_unmapped_get_kva(bp, blkno, size, flags); 3201 3202 /* 3203 * If the size is inconsistent in the VMIO case, we can resize 3204 * the buffer. This might lead to B_CACHE getting set or 3205 * cleared. If the size has not changed, B_CACHE remains 3206 * unchanged from its previous state. 3207 */ 3208 if (bp->b_bcount != size) 3209 allocbuf(bp, size); 3210 3211 KASSERT(bp->b_offset != NOOFFSET, 3212 ("getblk: no buffer offset")); 3213 3214 /* 3215 * A buffer with B_DELWRI set and B_CACHE clear must 3216 * be committed before we can return the buffer in 3217 * order to prevent the caller from issuing a read 3218 * ( due to B_CACHE not being set ) and overwriting 3219 * it. 3220 * 3221 * Most callers, including NFS and FFS, need this to 3222 * operate properly either because they assume they 3223 * can issue a read if B_CACHE is not set, or because 3224 * ( for example ) an uncached B_DELWRI might loop due 3225 * to softupdates re-dirtying the buffer. In the latter 3226 * case, B_CACHE is set after the first write completes, 3227 * preventing further loops. 3228 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 3229 * above while extending the buffer, we cannot allow the 3230 * buffer to remain with B_CACHE set after the write 3231 * completes or it will represent a corrupt state. To 3232 * deal with this we set B_NOCACHE to scrap the buffer 3233 * after the write. 3234 * 3235 * We might be able to do something fancy, like setting 3236 * B_CACHE in bwrite() except if B_DELWRI is already set, 3237 * so the below call doesn't set B_CACHE, but that gets real 3238 * confusing. This is much easier. 3239 */ 3240 3241 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 3242 bp->b_flags |= B_NOCACHE; 3243 bwrite(bp); 3244 goto loop; 3245 } 3246 bp->b_flags &= ~B_DONE; 3247 } else { 3248 /* 3249 * Buffer is not in-core, create new buffer. The buffer 3250 * returned by getnewbuf() is locked. Note that the returned 3251 * buffer is also considered valid (not marked B_INVAL). 3252 */ 3253 BO_RUNLOCK(bo); 3254 /* 3255 * If the user does not want us to create the buffer, bail out 3256 * here. 3257 */ 3258 if (flags & GB_NOCREAT) 3259 return NULL; 3260 if (numfreebuffers == 0 && TD_IS_IDLETHREAD(curthread)) 3261 return NULL; 3262 3263 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize; 3264 offset = blkno * bsize; 3265 vmio = vp->v_object != NULL; 3266 if (vmio) { 3267 maxsize = size + (offset & PAGE_MASK); 3268 } else { 3269 maxsize = size; 3270 /* Do not allow non-VMIO notmapped buffers. */ 3271 flags &= ~GB_UNMAPPED; 3272 } 3273 maxsize = imax(maxsize, bsize); 3274 3275 bp = getnewbuf(vp, slpflag, slptimeo, size, maxsize, flags); 3276 if (bp == NULL) { 3277 if (slpflag || slptimeo) 3278 return NULL; 3279 goto loop; 3280 } 3281 3282 /* 3283 * This code is used to make sure that a buffer is not 3284 * created while the getnewbuf routine is blocked. 3285 * This can be a problem whether the vnode is locked or not. 3286 * If the buffer is created out from under us, we have to 3287 * throw away the one we just created. 3288 * 3289 * Note: this must occur before we associate the buffer 3290 * with the vp especially considering limitations in 3291 * the splay tree implementation when dealing with duplicate 3292 * lblkno's. 3293 */ 3294 BO_LOCK(bo); 3295 if (gbincore(bo, blkno)) { 3296 BO_UNLOCK(bo); 3297 bp->b_flags |= B_INVAL; 3298 brelse(bp); 3299 goto loop; 3300 } 3301 3302 /* 3303 * Insert the buffer into the hash, so that it can 3304 * be found by incore. 3305 */ 3306 bp->b_blkno = bp->b_lblkno = blkno; 3307 bp->b_offset = offset; 3308 bgetvp(vp, bp); 3309 BO_UNLOCK(bo); 3310 3311 /* 3312 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 3313 * buffer size starts out as 0, B_CACHE will be set by 3314 * allocbuf() for the VMIO case prior to it testing the 3315 * backing store for validity. 3316 */ 3317 3318 if (vmio) { 3319 bp->b_flags |= B_VMIO; 3320 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 3321 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 3322 bp, vp->v_object, bp->b_bufobj->bo_object)); 3323 } else { 3324 bp->b_flags &= ~B_VMIO; 3325 KASSERT(bp->b_bufobj->bo_object == NULL, 3326 ("ARGH! has b_bufobj->bo_object %p %p\n", 3327 bp, bp->b_bufobj->bo_object)); 3328 BUF_CHECK_MAPPED(bp); 3329 } 3330 3331 allocbuf(bp, size); 3332 bp->b_flags &= ~B_DONE; 3333 } 3334 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 3335 BUF_ASSERT_HELD(bp); 3336end: 3337 KASSERT(bp->b_bufobj == bo, 3338 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 3339 return (bp); 3340} 3341 3342/* 3343 * Get an empty, disassociated buffer of given size. The buffer is initially 3344 * set to B_INVAL. 3345 */ 3346struct buf * 3347geteblk(int size, int flags) 3348{ 3349 struct buf *bp; 3350 int maxsize; 3351 3352 maxsize = (size + BKVAMASK) & ~BKVAMASK; 3353 while ((bp = getnewbuf(NULL, 0, 0, size, maxsize, flags)) == NULL) { 3354 if ((flags & GB_NOWAIT_BD) && 3355 (curthread->td_pflags & TDP_BUFNEED) != 0) 3356 return (NULL); 3357 } 3358 allocbuf(bp, size); 3359 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 3360 BUF_ASSERT_HELD(bp); 3361 return (bp); 3362} 3363 3364 3365/* 3366 * This code constitutes the buffer memory from either anonymous system 3367 * memory (in the case of non-VMIO operations) or from an associated 3368 * VM object (in the case of VMIO operations). This code is able to 3369 * resize a buffer up or down. 3370 * 3371 * Note that this code is tricky, and has many complications to resolve 3372 * deadlock or inconsistent data situations. Tread lightly!!! 3373 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 3374 * the caller. Calling this code willy nilly can result in the loss of data. 3375 * 3376 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 3377 * B_CACHE for the non-VMIO case. 3378 */ 3379 3380int 3381allocbuf(struct buf *bp, int size) 3382{ 3383 int newbsize, mbsize; 3384 int i; 3385 3386 BUF_ASSERT_HELD(bp); 3387 3388 if (bp->b_kvasize < size) 3389 panic("allocbuf: buffer too small"); 3390 3391 if ((bp->b_flags & B_VMIO) == 0) { 3392 caddr_t origbuf; 3393 int origbufsize; 3394 /* 3395 * Just get anonymous memory from the kernel. Don't 3396 * mess with B_CACHE. 3397 */ 3398 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3399 if (bp->b_flags & B_MALLOC) 3400 newbsize = mbsize; 3401 else 3402 newbsize = round_page(size); 3403 3404 if (newbsize < bp->b_bufsize) { 3405 /* 3406 * malloced buffers are not shrunk 3407 */ 3408 if (bp->b_flags & B_MALLOC) { 3409 if (newbsize) { 3410 bp->b_bcount = size; 3411 } else { 3412 free(bp->b_data, M_BIOBUF); 3413 if (bp->b_bufsize) { 3414 atomic_subtract_long( 3415 &bufmallocspace, 3416 bp->b_bufsize); 3417 bufspacewakeup(); 3418 bp->b_bufsize = 0; 3419 } 3420 bp->b_saveaddr = bp->b_kvabase; 3421 bp->b_data = bp->b_saveaddr; 3422 bp->b_bcount = 0; 3423 bp->b_flags &= ~B_MALLOC; 3424 } 3425 return 1; 3426 } 3427 vm_hold_free_pages(bp, newbsize); 3428 } else if (newbsize > bp->b_bufsize) { 3429 /* 3430 * We only use malloced memory on the first allocation. 3431 * and revert to page-allocated memory when the buffer 3432 * grows. 3433 */ 3434 /* 3435 * There is a potential smp race here that could lead 3436 * to bufmallocspace slightly passing the max. It 3437 * is probably extremely rare and not worth worrying 3438 * over. 3439 */ 3440 if ( (bufmallocspace < maxbufmallocspace) && 3441 (bp->b_bufsize == 0) && 3442 (mbsize <= PAGE_SIZE/2)) { 3443 3444 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 3445 bp->b_bufsize = mbsize; 3446 bp->b_bcount = size; 3447 bp->b_flags |= B_MALLOC; 3448 atomic_add_long(&bufmallocspace, mbsize); 3449 return 1; 3450 } 3451 origbuf = NULL; 3452 origbufsize = 0; 3453 /* 3454 * If the buffer is growing on its other-than-first allocation, 3455 * then we revert to the page-allocation scheme. 3456 */ 3457 if (bp->b_flags & B_MALLOC) { 3458 origbuf = bp->b_data; 3459 origbufsize = bp->b_bufsize; 3460 bp->b_data = bp->b_kvabase; 3461 if (bp->b_bufsize) { 3462 atomic_subtract_long(&bufmallocspace, 3463 bp->b_bufsize); 3464 bufspacewakeup(); 3465 bp->b_bufsize = 0; 3466 } 3467 bp->b_flags &= ~B_MALLOC; 3468 newbsize = round_page(newbsize); 3469 } 3470 vm_hold_load_pages( 3471 bp, 3472 (vm_offset_t) bp->b_data + bp->b_bufsize, 3473 (vm_offset_t) bp->b_data + newbsize); 3474 if (origbuf) { 3475 bcopy(origbuf, bp->b_data, origbufsize); 3476 free(origbuf, M_BIOBUF); 3477 } 3478 } 3479 } else { 3480 int desiredpages; 3481 3482 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3483 desiredpages = (size == 0) ? 0 : 3484 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 3485 3486 if (bp->b_flags & B_MALLOC) 3487 panic("allocbuf: VMIO buffer can't be malloced"); 3488 /* 3489 * Set B_CACHE initially if buffer is 0 length or will become 3490 * 0-length. 3491 */ 3492 if (size == 0 || bp->b_bufsize == 0) 3493 bp->b_flags |= B_CACHE; 3494 3495 if (newbsize < bp->b_bufsize) { 3496 /* 3497 * DEV_BSIZE aligned new buffer size is less then the 3498 * DEV_BSIZE aligned existing buffer size. Figure out 3499 * if we have to remove any pages. 3500 */ 3501 if (desiredpages < bp->b_npages) { 3502 vm_page_t m; 3503 3504 if ((bp->b_flags & B_UNMAPPED) == 0) { 3505 BUF_CHECK_MAPPED(bp); 3506 pmap_qremove((vm_offset_t)trunc_page( 3507 (vm_offset_t)bp->b_data) + 3508 (desiredpages << PAGE_SHIFT), 3509 (bp->b_npages - desiredpages)); 3510 } else 3511 BUF_CHECK_UNMAPPED(bp); 3512 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 3513 for (i = desiredpages; i < bp->b_npages; i++) { 3514 /* 3515 * the page is not freed here -- it 3516 * is the responsibility of 3517 * vnode_pager_setsize 3518 */ 3519 m = bp->b_pages[i]; 3520 KASSERT(m != bogus_page, 3521 ("allocbuf: bogus page found")); 3522 while (vm_page_sleep_if_busy(m, 3523 "biodep")) 3524 continue; 3525 3526 bp->b_pages[i] = NULL; 3527 vm_page_lock(m); 3528 vm_page_unwire(m, 0); 3529 vm_page_unlock(m); 3530 } 3531 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 3532 bp->b_npages = desiredpages; 3533 } 3534 } else if (size > bp->b_bcount) { 3535 /* 3536 * We are growing the buffer, possibly in a 3537 * byte-granular fashion. 3538 */ 3539 vm_object_t obj; 3540 vm_offset_t toff; 3541 vm_offset_t tinc; 3542 3543 /* 3544 * Step 1, bring in the VM pages from the object, 3545 * allocating them if necessary. We must clear 3546 * B_CACHE if these pages are not valid for the 3547 * range covered by the buffer. 3548 */ 3549 3550 obj = bp->b_bufobj->bo_object; 3551 3552 VM_OBJECT_WLOCK(obj); 3553 while (bp->b_npages < desiredpages) { 3554 vm_page_t m; 3555 3556 /* 3557 * We must allocate system pages since blocking 3558 * here could interfere with paging I/O, no 3559 * matter which process we are. 3560 * 3561 * Only exclusive busy can be tested here. 3562 * Blocking on shared busy might lead to 3563 * deadlocks once allocbuf() is called after 3564 * pages are vfs_busy_pages(). 3565 */ 3566 m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) + 3567 bp->b_npages, VM_ALLOC_NOBUSY | 3568 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED | 3569 VM_ALLOC_IGN_SBUSY | 3570 VM_ALLOC_COUNT(desiredpages - bp->b_npages)); 3571 if (m->valid == 0) 3572 bp->b_flags &= ~B_CACHE; 3573 bp->b_pages[bp->b_npages] = m; 3574 ++bp->b_npages; 3575 } 3576 3577 /* 3578 * Step 2. We've loaded the pages into the buffer, 3579 * we have to figure out if we can still have B_CACHE 3580 * set. Note that B_CACHE is set according to the 3581 * byte-granular range ( bcount and size ), new the 3582 * aligned range ( newbsize ). 3583 * 3584 * The VM test is against m->valid, which is DEV_BSIZE 3585 * aligned. Needless to say, the validity of the data 3586 * needs to also be DEV_BSIZE aligned. Note that this 3587 * fails with NFS if the server or some other client 3588 * extends the file's EOF. If our buffer is resized, 3589 * B_CACHE may remain set! XXX 3590 */ 3591 3592 toff = bp->b_bcount; 3593 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 3594 3595 while ((bp->b_flags & B_CACHE) && toff < size) { 3596 vm_pindex_t pi; 3597 3598 if (tinc > (size - toff)) 3599 tinc = size - toff; 3600 3601 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 3602 PAGE_SHIFT; 3603 3604 vfs_buf_test_cache( 3605 bp, 3606 bp->b_offset, 3607 toff, 3608 tinc, 3609 bp->b_pages[pi] 3610 ); 3611 toff += tinc; 3612 tinc = PAGE_SIZE; 3613 } 3614 VM_OBJECT_WUNLOCK(obj); 3615 3616 /* 3617 * Step 3, fixup the KVM pmap. 3618 */ 3619 if ((bp->b_flags & B_UNMAPPED) == 0) 3620 bpmap_qenter(bp); 3621 else 3622 BUF_CHECK_UNMAPPED(bp); 3623 } 3624 } 3625 if (newbsize < bp->b_bufsize) 3626 bufspacewakeup(); 3627 bp->b_bufsize = newbsize; /* actual buffer allocation */ 3628 bp->b_bcount = size; /* requested buffer size */ 3629 return 1; 3630} 3631 3632extern int inflight_transient_maps; 3633 3634void 3635biodone(struct bio *bp) 3636{ 3637 struct mtx *mtxp; 3638 void (*done)(struct bio *); 3639 vm_offset_t start, end; 3640 3641 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) { 3642 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING; 3643 bp->bio_flags |= BIO_UNMAPPED; 3644 start = trunc_page((vm_offset_t)bp->bio_data); 3645 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length); 3646 pmap_qremove(start, OFF_TO_IDX(end - start)); 3647 vmem_free(transient_arena, start, end - start); 3648 atomic_add_int(&inflight_transient_maps, -1); 3649 } 3650 done = bp->bio_done; 3651 if (done == NULL) { 3652 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3653 mtx_lock(mtxp); 3654 bp->bio_flags |= BIO_DONE; 3655 wakeup(bp); 3656 mtx_unlock(mtxp); 3657 } else { 3658 bp->bio_flags |= BIO_DONE; 3659 done(bp); 3660 } 3661} 3662 3663/* 3664 * Wait for a BIO to finish. 3665 */ 3666int 3667biowait(struct bio *bp, const char *wchan) 3668{ 3669 struct mtx *mtxp; 3670 3671 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3672 mtx_lock(mtxp); 3673 while ((bp->bio_flags & BIO_DONE) == 0) 3674 msleep(bp, mtxp, PRIBIO, wchan, 0); 3675 mtx_unlock(mtxp); 3676 if (bp->bio_error != 0) 3677 return (bp->bio_error); 3678 if (!(bp->bio_flags & BIO_ERROR)) 3679 return (0); 3680 return (EIO); 3681} 3682 3683void 3684biofinish(struct bio *bp, struct devstat *stat, int error) 3685{ 3686 3687 if (error) { 3688 bp->bio_error = error; 3689 bp->bio_flags |= BIO_ERROR; 3690 } 3691 if (stat != NULL) 3692 devstat_end_transaction_bio(stat, bp); 3693 biodone(bp); 3694} 3695 3696/* 3697 * bufwait: 3698 * 3699 * Wait for buffer I/O completion, returning error status. The buffer 3700 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3701 * error and cleared. 3702 */ 3703int 3704bufwait(struct buf *bp) 3705{ 3706 if (bp->b_iocmd == BIO_READ) 3707 bwait(bp, PRIBIO, "biord"); 3708 else 3709 bwait(bp, PRIBIO, "biowr"); 3710 if (bp->b_flags & B_EINTR) { 3711 bp->b_flags &= ~B_EINTR; 3712 return (EINTR); 3713 } 3714 if (bp->b_ioflags & BIO_ERROR) { 3715 return (bp->b_error ? bp->b_error : EIO); 3716 } else { 3717 return (0); 3718 } 3719} 3720 3721 /* 3722 * Call back function from struct bio back up to struct buf. 3723 */ 3724static void 3725bufdonebio(struct bio *bip) 3726{ 3727 struct buf *bp; 3728 3729 bp = bip->bio_caller2; 3730 bp->b_resid = bp->b_bcount - bip->bio_completed; 3731 bp->b_resid = bip->bio_resid; /* XXX: remove */ 3732 bp->b_ioflags = bip->bio_flags; 3733 bp->b_error = bip->bio_error; 3734 if (bp->b_error) 3735 bp->b_ioflags |= BIO_ERROR; 3736 bufdone(bp); 3737 g_destroy_bio(bip); 3738} 3739 3740void 3741dev_strategy(struct cdev *dev, struct buf *bp) 3742{ 3743 struct cdevsw *csw; 3744 int ref; 3745 3746 KASSERT(dev->si_refcount > 0, 3747 ("dev_strategy on un-referenced struct cdev *(%s) %p", 3748 devtoname(dev), dev)); 3749 3750 csw = dev_refthread(dev, &ref); 3751 dev_strategy_csw(dev, csw, bp); 3752 dev_relthread(dev, ref); 3753} 3754 3755void 3756dev_strategy_csw(struct cdev *dev, struct cdevsw *csw, struct buf *bp) 3757{ 3758 struct bio *bip; 3759 3760 KASSERT(bp->b_iocmd == BIO_READ || bp->b_iocmd == BIO_WRITE, 3761 ("b_iocmd botch")); 3762 KASSERT(((dev->si_flags & SI_ETERNAL) != 0 && csw != NULL) || 3763 dev->si_threadcount > 0, 3764 ("dev_strategy_csw threadcount cdev *(%s) %p", devtoname(dev), 3765 dev)); 3766 if (csw == NULL) { 3767 bp->b_error = ENXIO; 3768 bp->b_ioflags = BIO_ERROR; 3769 bufdone(bp); 3770 return; 3771 } 3772 for (;;) { 3773 bip = g_new_bio(); 3774 if (bip != NULL) 3775 break; 3776 /* Try again later */ 3777 tsleep(&bp, PRIBIO, "dev_strat", hz/10); 3778 } 3779 bip->bio_cmd = bp->b_iocmd; 3780 bip->bio_offset = bp->b_iooffset; 3781 bip->bio_length = bp->b_bcount; 3782 bip->bio_bcount = bp->b_bcount; /* XXX: remove */ 3783 bdata2bio(bp, bip); 3784 bip->bio_done = bufdonebio; 3785 bip->bio_caller2 = bp; 3786 bip->bio_dev = dev; 3787 (*csw->d_strategy)(bip); 3788} 3789 3790/* 3791 * bufdone: 3792 * 3793 * Finish I/O on a buffer, optionally calling a completion function. 3794 * This is usually called from an interrupt so process blocking is 3795 * not allowed. 3796 * 3797 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3798 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3799 * assuming B_INVAL is clear. 3800 * 3801 * For the VMIO case, we set B_CACHE if the op was a read and no 3802 * read error occurred, or if the op was a write. B_CACHE is never 3803 * set if the buffer is invalid or otherwise uncacheable. 3804 * 3805 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3806 * initiator to leave B_INVAL set to brelse the buffer out of existence 3807 * in the biodone routine. 3808 */ 3809void 3810bufdone(struct buf *bp) 3811{ 3812 struct bufobj *dropobj; 3813 void (*biodone)(struct buf *); 3814 3815 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 3816 dropobj = NULL; 3817 3818 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 3819 BUF_ASSERT_HELD(bp); 3820 3821 runningbufwakeup(bp); 3822 if (bp->b_iocmd == BIO_WRITE) 3823 dropobj = bp->b_bufobj; 3824 /* call optional completion function if requested */ 3825 if (bp->b_iodone != NULL) { 3826 biodone = bp->b_iodone; 3827 bp->b_iodone = NULL; 3828 (*biodone) (bp); 3829 if (dropobj) 3830 bufobj_wdrop(dropobj); 3831 return; 3832 } 3833 3834 bufdone_finish(bp); 3835 3836 if (dropobj) 3837 bufobj_wdrop(dropobj); 3838} 3839 3840void 3841bufdone_finish(struct buf *bp) 3842{ 3843 BUF_ASSERT_HELD(bp); 3844 3845 if (!LIST_EMPTY(&bp->b_dep)) 3846 buf_complete(bp); 3847 3848 if (bp->b_flags & B_VMIO) { 3849 vm_ooffset_t foff; 3850 vm_page_t m; 3851 vm_object_t obj; 3852 struct vnode *vp; 3853 int bogus, i, iosize; 3854 3855 obj = bp->b_bufobj->bo_object; 3856 KASSERT(obj->paging_in_progress >= bp->b_npages, 3857 ("biodone_finish: paging in progress(%d) < b_npages(%d)", 3858 obj->paging_in_progress, bp->b_npages)); 3859 3860 vp = bp->b_vp; 3861 KASSERT(vp->v_holdcnt > 0, 3862 ("biodone_finish: vnode %p has zero hold count", vp)); 3863 KASSERT(vp->v_object != NULL, 3864 ("biodone_finish: vnode %p has no vm_object", vp)); 3865 3866 foff = bp->b_offset; 3867 KASSERT(bp->b_offset != NOOFFSET, 3868 ("biodone_finish: bp %p has no buffer offset", bp)); 3869 3870 /* 3871 * Set B_CACHE if the op was a normal read and no error 3872 * occurred. B_CACHE is set for writes in the b*write() 3873 * routines. 3874 */ 3875 iosize = bp->b_bcount - bp->b_resid; 3876 if (bp->b_iocmd == BIO_READ && 3877 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 3878 !(bp->b_ioflags & BIO_ERROR)) { 3879 bp->b_flags |= B_CACHE; 3880 } 3881 bogus = 0; 3882 VM_OBJECT_WLOCK(obj); 3883 for (i = 0; i < bp->b_npages; i++) { 3884 int bogusflag = 0; 3885 int resid; 3886 3887 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 3888 if (resid > iosize) 3889 resid = iosize; 3890 3891 /* 3892 * cleanup bogus pages, restoring the originals 3893 */ 3894 m = bp->b_pages[i]; 3895 if (m == bogus_page) { 3896 bogus = bogusflag = 1; 3897 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3898 if (m == NULL) 3899 panic("biodone: page disappeared!"); 3900 bp->b_pages[i] = m; 3901 } 3902 KASSERT(OFF_TO_IDX(foff) == m->pindex, 3903 ("biodone_finish: foff(%jd)/pindex(%ju) mismatch", 3904 (intmax_t)foff, (uintmax_t)m->pindex)); 3905 3906 /* 3907 * In the write case, the valid and clean bits are 3908 * already changed correctly ( see bdwrite() ), so we 3909 * only need to do this here in the read case. 3910 */ 3911 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 3912 KASSERT((m->dirty & vm_page_bits(foff & 3913 PAGE_MASK, resid)) == 0, ("bufdone_finish:" 3914 " page %p has unexpected dirty bits", m)); 3915 vfs_page_set_valid(bp, foff, m); 3916 } 3917 3918 vm_page_sunbusy(m); 3919 vm_object_pip_subtract(obj, 1); 3920 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3921 iosize -= resid; 3922 } 3923 vm_object_pip_wakeupn(obj, 0); 3924 VM_OBJECT_WUNLOCK(obj); 3925 if (bogus && (bp->b_flags & B_UNMAPPED) == 0) { 3926 BUF_CHECK_MAPPED(bp); 3927 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3928 bp->b_pages, bp->b_npages); 3929 } 3930 } 3931 3932 /* 3933 * For asynchronous completions, release the buffer now. The brelse 3934 * will do a wakeup there if necessary - so no need to do a wakeup 3935 * here in the async case. The sync case always needs to do a wakeup. 3936 */ 3937 3938 if (bp->b_flags & B_ASYNC) { 3939 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 3940 brelse(bp); 3941 else 3942 bqrelse(bp); 3943 } else 3944 bdone(bp); 3945} 3946 3947/* 3948 * This routine is called in lieu of iodone in the case of 3949 * incomplete I/O. This keeps the busy status for pages 3950 * consistent. 3951 */ 3952void 3953vfs_unbusy_pages(struct buf *bp) 3954{ 3955 int i; 3956 vm_object_t obj; 3957 vm_page_t m; 3958 3959 runningbufwakeup(bp); 3960 if (!(bp->b_flags & B_VMIO)) 3961 return; 3962 3963 obj = bp->b_bufobj->bo_object; 3964 VM_OBJECT_WLOCK(obj); 3965 for (i = 0; i < bp->b_npages; i++) { 3966 m = bp->b_pages[i]; 3967 if (m == bogus_page) { 3968 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 3969 if (!m) 3970 panic("vfs_unbusy_pages: page missing\n"); 3971 bp->b_pages[i] = m; 3972 if ((bp->b_flags & B_UNMAPPED) == 0) { 3973 BUF_CHECK_MAPPED(bp); 3974 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3975 bp->b_pages, bp->b_npages); 3976 } else 3977 BUF_CHECK_UNMAPPED(bp); 3978 } 3979 vm_object_pip_subtract(obj, 1); 3980 vm_page_sunbusy(m); 3981 } 3982 vm_object_pip_wakeupn(obj, 0); 3983 VM_OBJECT_WUNLOCK(obj); 3984} 3985 3986/* 3987 * vfs_page_set_valid: 3988 * 3989 * Set the valid bits in a page based on the supplied offset. The 3990 * range is restricted to the buffer's size. 3991 * 3992 * This routine is typically called after a read completes. 3993 */ 3994static void 3995vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3996{ 3997 vm_ooffset_t eoff; 3998 3999 /* 4000 * Compute the end offset, eoff, such that [off, eoff) does not span a 4001 * page boundary and eoff is not greater than the end of the buffer. 4002 * The end of the buffer, in this case, is our file EOF, not the 4003 * allocation size of the buffer. 4004 */ 4005 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 4006 if (eoff > bp->b_offset + bp->b_bcount) 4007 eoff = bp->b_offset + bp->b_bcount; 4008 4009 /* 4010 * Set valid range. This is typically the entire buffer and thus the 4011 * entire page. 4012 */ 4013 if (eoff > off) 4014 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off); 4015} 4016 4017/* 4018 * vfs_page_set_validclean: 4019 * 4020 * Set the valid bits and clear the dirty bits in a page based on the 4021 * supplied offset. The range is restricted to the buffer's size. 4022 */ 4023static void 4024vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4025{ 4026 vm_ooffset_t soff, eoff; 4027 4028 /* 4029 * Start and end offsets in buffer. eoff - soff may not cross a 4030 * page boundary or cross the end of the buffer. The end of the 4031 * buffer, in this case, is our file EOF, not the allocation size 4032 * of the buffer. 4033 */ 4034 soff = off; 4035 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4036 if (eoff > bp->b_offset + bp->b_bcount) 4037 eoff = bp->b_offset + bp->b_bcount; 4038 4039 /* 4040 * Set valid range. This is typically the entire buffer and thus the 4041 * entire page. 4042 */ 4043 if (eoff > soff) { 4044 vm_page_set_validclean( 4045 m, 4046 (vm_offset_t) (soff & PAGE_MASK), 4047 (vm_offset_t) (eoff - soff) 4048 ); 4049 } 4050} 4051 4052/* 4053 * Ensure that all buffer pages are not exclusive busied. If any page is 4054 * exclusive busy, drain it. 4055 */ 4056void 4057vfs_drain_busy_pages(struct buf *bp) 4058{ 4059 vm_page_t m; 4060 int i, last_busied; 4061 4062 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object); 4063 last_busied = 0; 4064 for (i = 0; i < bp->b_npages; i++) { 4065 m = bp->b_pages[i]; 4066 if (vm_page_xbusied(m)) { 4067 for (; last_busied < i; last_busied++) 4068 vm_page_sbusy(bp->b_pages[last_busied]); 4069 while (vm_page_xbusied(m)) { 4070 vm_page_lock(m); 4071 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4072 vm_page_busy_sleep(m, "vbpage", true); 4073 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4074 } 4075 } 4076 } 4077 for (i = 0; i < last_busied; i++) 4078 vm_page_sunbusy(bp->b_pages[i]); 4079} 4080 4081/* 4082 * This routine is called before a device strategy routine. 4083 * It is used to tell the VM system that paging I/O is in 4084 * progress, and treat the pages associated with the buffer 4085 * almost as being exclusive busy. Also the object paging_in_progress 4086 * flag is handled to make sure that the object doesn't become 4087 * inconsistent. 4088 * 4089 * Since I/O has not been initiated yet, certain buffer flags 4090 * such as BIO_ERROR or B_INVAL may be in an inconsistent state 4091 * and should be ignored. 4092 */ 4093void 4094vfs_busy_pages(struct buf *bp, int clear_modify) 4095{ 4096 int i, bogus; 4097 vm_object_t obj; 4098 vm_ooffset_t foff; 4099 vm_page_t m; 4100 4101 if (!(bp->b_flags & B_VMIO)) 4102 return; 4103 4104 obj = bp->b_bufobj->bo_object; 4105 foff = bp->b_offset; 4106 KASSERT(bp->b_offset != NOOFFSET, 4107 ("vfs_busy_pages: no buffer offset")); 4108 VM_OBJECT_WLOCK(obj); 4109 vfs_drain_busy_pages(bp); 4110 if (bp->b_bufsize != 0) 4111 vfs_setdirty_locked_object(bp); 4112 bogus = 0; 4113 for (i = 0; i < bp->b_npages; i++) { 4114 m = bp->b_pages[i]; 4115 4116 if ((bp->b_flags & B_CLUSTER) == 0) { 4117 vm_object_pip_add(obj, 1); 4118 vm_page_sbusy(m); 4119 } 4120 /* 4121 * When readying a buffer for a read ( i.e 4122 * clear_modify == 0 ), it is important to do 4123 * bogus_page replacement for valid pages in 4124 * partially instantiated buffers. Partially 4125 * instantiated buffers can, in turn, occur when 4126 * reconstituting a buffer from its VM backing store 4127 * base. We only have to do this if B_CACHE is 4128 * clear ( which causes the I/O to occur in the 4129 * first place ). The replacement prevents the read 4130 * I/O from overwriting potentially dirty VM-backed 4131 * pages. XXX bogus page replacement is, uh, bogus. 4132 * It may not work properly with small-block devices. 4133 * We need to find a better way. 4134 */ 4135 if (clear_modify) { 4136 pmap_remove_write(m); 4137 vfs_page_set_validclean(bp, foff, m); 4138 } else if (m->valid == VM_PAGE_BITS_ALL && 4139 (bp->b_flags & B_CACHE) == 0) { 4140 bp->b_pages[i] = bogus_page; 4141 bogus++; 4142 } 4143 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4144 } 4145 VM_OBJECT_WUNLOCK(obj); 4146 if (bogus && (bp->b_flags & B_UNMAPPED) == 0) { 4147 BUF_CHECK_MAPPED(bp); 4148 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4149 bp->b_pages, bp->b_npages); 4150 } 4151} 4152 4153/* 4154 * vfs_bio_set_valid: 4155 * 4156 * Set the range within the buffer to valid. The range is 4157 * relative to the beginning of the buffer, b_offset. Note that 4158 * b_offset itself may be offset from the beginning of the first 4159 * page. 4160 */ 4161void 4162vfs_bio_set_valid(struct buf *bp, int base, int size) 4163{ 4164 int i, n; 4165 vm_page_t m; 4166 4167 if (!(bp->b_flags & B_VMIO)) 4168 return; 4169 4170 /* 4171 * Fixup base to be relative to beginning of first page. 4172 * Set initial n to be the maximum number of bytes in the 4173 * first page that can be validated. 4174 */ 4175 base += (bp->b_offset & PAGE_MASK); 4176 n = PAGE_SIZE - (base & PAGE_MASK); 4177 4178 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4179 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4180 m = bp->b_pages[i]; 4181 if (n > size) 4182 n = size; 4183 vm_page_set_valid_range(m, base & PAGE_MASK, n); 4184 base += n; 4185 size -= n; 4186 n = PAGE_SIZE; 4187 } 4188 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4189} 4190 4191/* 4192 * vfs_bio_clrbuf: 4193 * 4194 * If the specified buffer is a non-VMIO buffer, clear the entire 4195 * buffer. If the specified buffer is a VMIO buffer, clear and 4196 * validate only the previously invalid portions of the buffer. 4197 * This routine essentially fakes an I/O, so we need to clear 4198 * BIO_ERROR and B_INVAL. 4199 * 4200 * Note that while we only theoretically need to clear through b_bcount, 4201 * we go ahead and clear through b_bufsize. 4202 */ 4203void 4204vfs_bio_clrbuf(struct buf *bp) 4205{ 4206 int i, j, mask, sa, ea, slide; 4207 4208 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 4209 clrbuf(bp); 4210 return; 4211 } 4212 bp->b_flags &= ~B_INVAL; 4213 bp->b_ioflags &= ~BIO_ERROR; 4214 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4215 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 4216 (bp->b_offset & PAGE_MASK) == 0) { 4217 if (bp->b_pages[0] == bogus_page) 4218 goto unlock; 4219 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 4220 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object); 4221 if ((bp->b_pages[0]->valid & mask) == mask) 4222 goto unlock; 4223 if ((bp->b_pages[0]->valid & mask) == 0) { 4224 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize); 4225 bp->b_pages[0]->valid |= mask; 4226 goto unlock; 4227 } 4228 } 4229 sa = bp->b_offset & PAGE_MASK; 4230 slide = 0; 4231 for (i = 0; i < bp->b_npages; i++, sa = 0) { 4232 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize); 4233 ea = slide & PAGE_MASK; 4234 if (ea == 0) 4235 ea = PAGE_SIZE; 4236 if (bp->b_pages[i] == bogus_page) 4237 continue; 4238 j = sa / DEV_BSIZE; 4239 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 4240 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object); 4241 if ((bp->b_pages[i]->valid & mask) == mask) 4242 continue; 4243 if ((bp->b_pages[i]->valid & mask) == 0) 4244 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa); 4245 else { 4246 for (; sa < ea; sa += DEV_BSIZE, j++) { 4247 if ((bp->b_pages[i]->valid & (1 << j)) == 0) { 4248 pmap_zero_page_area(bp->b_pages[i], 4249 sa, DEV_BSIZE); 4250 } 4251 } 4252 } 4253 bp->b_pages[i]->valid |= mask; 4254 } 4255unlock: 4256 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4257 bp->b_resid = 0; 4258} 4259 4260void 4261vfs_bio_bzero_buf(struct buf *bp, int base, int size) 4262{ 4263 vm_page_t m; 4264 int i, n; 4265 4266 if ((bp->b_flags & B_UNMAPPED) == 0) { 4267 BUF_CHECK_MAPPED(bp); 4268 bzero(bp->b_data + base, size); 4269 } else { 4270 BUF_CHECK_UNMAPPED(bp); 4271 n = PAGE_SIZE - (base & PAGE_MASK); 4272 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4273 m = bp->b_pages[i]; 4274 if (n > size) 4275 n = size; 4276 pmap_zero_page_area(m, base & PAGE_MASK, n); 4277 base += n; 4278 size -= n; 4279 n = PAGE_SIZE; 4280 } 4281 } 4282} 4283 4284/* 4285 * vm_hold_load_pages and vm_hold_free_pages get pages into 4286 * a buffers address space. The pages are anonymous and are 4287 * not associated with a file object. 4288 */ 4289static void 4290vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4291{ 4292 vm_offset_t pg; 4293 vm_page_t p; 4294 int index; 4295 4296 BUF_CHECK_MAPPED(bp); 4297 4298 to = round_page(to); 4299 from = round_page(from); 4300 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4301 4302 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 4303tryagain: 4304 /* 4305 * note: must allocate system pages since blocking here 4306 * could interfere with paging I/O, no matter which 4307 * process we are. 4308 */ 4309 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ | 4310 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT)); 4311 if (p == NULL) { 4312 VM_WAIT; 4313 goto tryagain; 4314 } 4315 pmap_qenter(pg, &p, 1); 4316 bp->b_pages[index] = p; 4317 } 4318 bp->b_npages = index; 4319} 4320 4321/* Return pages associated with this buf to the vm system */ 4322static void 4323vm_hold_free_pages(struct buf *bp, int newbsize) 4324{ 4325 vm_offset_t from; 4326 vm_page_t p; 4327 int index, newnpages; 4328 4329 BUF_CHECK_MAPPED(bp); 4330 4331 from = round_page((vm_offset_t)bp->b_data + newbsize); 4332 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4333 if (bp->b_npages > newnpages) 4334 pmap_qremove(from, bp->b_npages - newnpages); 4335 for (index = newnpages; index < bp->b_npages; index++) { 4336 p = bp->b_pages[index]; 4337 bp->b_pages[index] = NULL; 4338 if (vm_page_sbusied(p)) 4339 printf("vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 4340 (intmax_t)bp->b_blkno, (intmax_t)bp->b_lblkno); 4341 p->wire_count--; 4342 vm_page_free(p); 4343 atomic_subtract_int(&cnt.v_wire_count, 1); 4344 } 4345 bp->b_npages = newnpages; 4346} 4347 4348/* 4349 * Map an IO request into kernel virtual address space. 4350 * 4351 * All requests are (re)mapped into kernel VA space. 4352 * Notice that we use b_bufsize for the size of the buffer 4353 * to be mapped. b_bcount might be modified by the driver. 4354 * 4355 * Note that even if the caller determines that the address space should 4356 * be valid, a race or a smaller-file mapped into a larger space may 4357 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 4358 * check the return value. 4359 */ 4360int 4361vmapbuf(struct buf *bp, int mapbuf) 4362{ 4363 caddr_t kva; 4364 vm_prot_t prot; 4365 int pidx; 4366 4367 if (bp->b_bufsize < 0) 4368 return (-1); 4369 prot = VM_PROT_READ; 4370 if (bp->b_iocmd == BIO_READ) 4371 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 4372 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 4373 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages, 4374 btoc(MAXPHYS))) < 0) 4375 return (-1); 4376 bp->b_npages = pidx; 4377 if (mapbuf || !unmapped_buf_allowed) { 4378 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx); 4379 kva = bp->b_saveaddr; 4380 bp->b_saveaddr = bp->b_data; 4381 bp->b_data = kva + (((vm_offset_t)bp->b_data) & PAGE_MASK); 4382 bp->b_flags &= ~B_UNMAPPED; 4383 } else { 4384 bp->b_flags |= B_UNMAPPED; 4385 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK; 4386 bp->b_saveaddr = bp->b_data; 4387 bp->b_data = unmapped_buf; 4388 } 4389 return(0); 4390} 4391 4392/* 4393 * Free the io map PTEs associated with this IO operation. 4394 * We also invalidate the TLB entries and restore the original b_addr. 4395 */ 4396void 4397vunmapbuf(struct buf *bp) 4398{ 4399 int npages; 4400 4401 npages = bp->b_npages; 4402 if (bp->b_flags & B_UNMAPPED) 4403 bp->b_flags &= ~B_UNMAPPED; 4404 else 4405 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 4406 vm_page_unhold_pages(bp->b_pages, npages); 4407 4408 bp->b_data = bp->b_saveaddr; 4409} 4410 4411void 4412bdone(struct buf *bp) 4413{ 4414 struct mtx *mtxp; 4415 4416 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4417 mtx_lock(mtxp); 4418 bp->b_flags |= B_DONE; 4419 wakeup(bp); 4420 mtx_unlock(mtxp); 4421} 4422 4423void 4424bwait(struct buf *bp, u_char pri, const char *wchan) 4425{ 4426 struct mtx *mtxp; 4427 4428 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4429 mtx_lock(mtxp); 4430 while ((bp->b_flags & B_DONE) == 0) 4431 msleep(bp, mtxp, pri, wchan, 0); 4432 mtx_unlock(mtxp); 4433} 4434 4435int 4436bufsync(struct bufobj *bo, int waitfor) 4437{ 4438 4439 return (VOP_FSYNC(bo->__bo_vnode, waitfor, curthread)); 4440} 4441 4442void 4443bufstrategy(struct bufobj *bo, struct buf *bp) 4444{ 4445 int i = 0; 4446 struct vnode *vp; 4447 4448 vp = bp->b_vp; 4449 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 4450 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 4451 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 4452 i = VOP_STRATEGY(vp, bp); 4453 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 4454} 4455 4456void 4457bufobj_wrefl(struct bufobj *bo) 4458{ 4459 4460 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4461 ASSERT_BO_WLOCKED(bo); 4462 bo->bo_numoutput++; 4463} 4464 4465void 4466bufobj_wref(struct bufobj *bo) 4467{ 4468 4469 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4470 BO_LOCK(bo); 4471 bo->bo_numoutput++; 4472 BO_UNLOCK(bo); 4473} 4474 4475void 4476bufobj_wdrop(struct bufobj *bo) 4477{ 4478 4479 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 4480 BO_LOCK(bo); 4481 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 4482 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 4483 bo->bo_flag &= ~BO_WWAIT; 4484 wakeup(&bo->bo_numoutput); 4485 } 4486 BO_UNLOCK(bo); 4487} 4488 4489int 4490bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 4491{ 4492 int error; 4493 4494 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 4495 ASSERT_BO_WLOCKED(bo); 4496 error = 0; 4497 while (bo->bo_numoutput) { 4498 bo->bo_flag |= BO_WWAIT; 4499 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo), 4500 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 4501 if (error) 4502 break; 4503 } 4504 return (error); 4505} 4506 4507void 4508bpin(struct buf *bp) 4509{ 4510 struct mtx *mtxp; 4511 4512 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4513 mtx_lock(mtxp); 4514 bp->b_pin_count++; 4515 mtx_unlock(mtxp); 4516} 4517 4518void 4519bunpin(struct buf *bp) 4520{ 4521 struct mtx *mtxp; 4522 4523 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4524 mtx_lock(mtxp); 4525 if (--bp->b_pin_count == 0) 4526 wakeup(bp); 4527 mtx_unlock(mtxp); 4528} 4529 4530void 4531bunpin_wait(struct buf *bp) 4532{ 4533 struct mtx *mtxp; 4534 4535 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4536 mtx_lock(mtxp); 4537 while (bp->b_pin_count > 0) 4538 msleep(bp, mtxp, PRIBIO, "bwunpin", 0); 4539 mtx_unlock(mtxp); 4540} 4541 4542/* 4543 * Set bio_data or bio_ma for struct bio from the struct buf. 4544 */ 4545void 4546bdata2bio(struct buf *bp, struct bio *bip) 4547{ 4548 4549 if ((bp->b_flags & B_UNMAPPED) != 0) { 4550 KASSERT(unmapped_buf_allowed, ("unmapped")); 4551 bip->bio_ma = bp->b_pages; 4552 bip->bio_ma_n = bp->b_npages; 4553 bip->bio_data = unmapped_buf; 4554 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 4555 bip->bio_flags |= BIO_UNMAPPED; 4556 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) / 4557 PAGE_SIZE == bp->b_npages, 4558 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset, 4559 (long long)bip->bio_length, bip->bio_ma_n)); 4560 } else { 4561 bip->bio_data = bp->b_data; 4562 bip->bio_ma = NULL; 4563 } 4564} 4565 4566#include "opt_ddb.h" 4567#ifdef DDB 4568#include <ddb/ddb.h> 4569 4570/* DDB command to show buffer data */ 4571DB_SHOW_COMMAND(buffer, db_show_buffer) 4572{ 4573 /* get args */ 4574 struct buf *bp = (struct buf *)addr; 4575 4576 if (!have_addr) { 4577 db_printf("usage: show buffer <addr>\n"); 4578 return; 4579 } 4580 4581 db_printf("buf at %p\n", bp); 4582 db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n", 4583 (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags, 4584 PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS); 4585 db_printf( 4586 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 4587 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, " 4588 "b_dep = %p\n", 4589 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 4590 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 4591 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first); 4592 if (bp->b_npages) { 4593 int i; 4594 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 4595 for (i = 0; i < bp->b_npages; i++) { 4596 vm_page_t m; 4597 m = bp->b_pages[i]; 4598 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 4599 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 4600 if ((i + 1) < bp->b_npages) 4601 db_printf(","); 4602 } 4603 db_printf("\n"); 4604 } 4605 db_printf(" "); 4606 BUF_LOCKPRINTINFO(bp); 4607} 4608 4609DB_SHOW_COMMAND(lockedbufs, lockedbufs) 4610{ 4611 struct buf *bp; 4612 int i; 4613 4614 for (i = 0; i < nbuf; i++) { 4615 bp = &buf[i]; 4616 if (BUF_ISLOCKED(bp)) { 4617 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4618 db_printf("\n"); 4619 } 4620 } 4621} 4622 4623DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 4624{ 4625 struct vnode *vp; 4626 struct buf *bp; 4627 4628 if (!have_addr) { 4629 db_printf("usage: show vnodebufs <addr>\n"); 4630 return; 4631 } 4632 vp = (struct vnode *)addr; 4633 db_printf("Clean buffers:\n"); 4634 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 4635 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4636 db_printf("\n"); 4637 } 4638 db_printf("Dirty buffers:\n"); 4639 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 4640 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4641 db_printf("\n"); 4642 } 4643} 4644 4645DB_COMMAND(countfreebufs, db_coundfreebufs) 4646{ 4647 struct buf *bp; 4648 int i, used = 0, nfree = 0; 4649 4650 if (have_addr) { 4651 db_printf("usage: countfreebufs\n"); 4652 return; 4653 } 4654 4655 for (i = 0; i < nbuf; i++) { 4656 bp = &buf[i]; 4657 if ((bp->b_flags & B_INFREECNT) != 0) 4658 nfree++; 4659 else 4660 used++; 4661 } 4662 4663 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 4664 nfree + used); 4665 db_printf("numfreebuffers is %d\n", numfreebuffers); 4666} 4667#endif /* DDB */ 4668