vfs_bio.c revision 316073
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/11/sys/kern/vfs_bio.c 316073 2017-03-28 06:07:59Z 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/racct.h> 65#include <sys/resourcevar.h> 66#include <sys/rwlock.h> 67#include <sys/smp.h> 68#include <sys/sysctl.h> 69#include <sys/sysproto.h> 70#include <sys/vmem.h> 71#include <sys/vmmeter.h> 72#include <sys/vnode.h> 73#include <sys/watchdog.h> 74#include <geom/geom.h> 75#include <vm/vm.h> 76#include <vm/vm_param.h> 77#include <vm/vm_kern.h> 78#include <vm/vm_object.h> 79#include <vm/vm_page.h> 80#include <vm/vm_pageout.h> 81#include <vm/vm_pager.h> 82#include <vm/vm_extern.h> 83#include <vm/vm_map.h> 84#include <vm/swap_pager.h> 85#include "opt_compat.h" 86#include "opt_swap.h" 87 88static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer"); 89 90struct bio_ops bioops; /* I/O operation notification */ 91 92struct buf_ops buf_ops_bio = { 93 .bop_name = "buf_ops_bio", 94 .bop_write = bufwrite, 95 .bop_strategy = bufstrategy, 96 .bop_sync = bufsync, 97 .bop_bdflush = bufbdflush, 98}; 99 100static struct buf *buf; /* buffer header pool */ 101extern struct buf *swbuf; /* Swap buffer header pool. */ 102caddr_t unmapped_buf; 103 104/* Used below and for softdep flushing threads in ufs/ffs/ffs_softdep.c */ 105struct proc *bufdaemonproc; 106struct proc *bufspacedaemonproc; 107 108static int inmem(struct vnode *vp, daddr_t blkno); 109static void vm_hold_free_pages(struct buf *bp, int newbsize); 110static void vm_hold_load_pages(struct buf *bp, vm_offset_t from, 111 vm_offset_t to); 112static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m); 113static void vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, 114 vm_page_t m); 115static void vfs_clean_pages_dirty_buf(struct buf *bp); 116static void vfs_setdirty_locked_object(struct buf *bp); 117static void vfs_vmio_invalidate(struct buf *bp); 118static void vfs_vmio_truncate(struct buf *bp, int npages); 119static void vfs_vmio_extend(struct buf *bp, int npages, int size); 120static int vfs_bio_clcheck(struct vnode *vp, int size, 121 daddr_t lblkno, daddr_t blkno); 122static int buf_flush(struct vnode *vp, int); 123static int buf_recycle(bool); 124static int buf_scan(bool); 125static int flushbufqueues(struct vnode *, int, int); 126static void buf_daemon(void); 127static void bremfreel(struct buf *bp); 128static __inline void bd_wakeup(void); 129static int sysctl_runningspace(SYSCTL_HANDLER_ARGS); 130static void bufkva_reclaim(vmem_t *, int); 131static void bufkva_free(struct buf *); 132static int buf_import(void *, void **, int, int); 133static void buf_release(void *, void **, int); 134 135#if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 136 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 137static int sysctl_bufspace(SYSCTL_HANDLER_ARGS); 138#endif 139 140int vmiodirenable = TRUE; 141SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, 142 "Use the VM system for directory writes"); 143long runningbufspace; 144SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 145 "Amount of presently outstanding async buffer io"); 146static long bufspace; 147#if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 148 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 149SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD, 150 &bufspace, 0, sysctl_bufspace, "L", "Virtual memory used for buffers"); 151#else 152SYSCTL_LONG(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, 153 "Physical memory used for buffers"); 154#endif 155static long bufkvaspace; 156SYSCTL_LONG(_vfs, OID_AUTO, bufkvaspace, CTLFLAG_RD, &bufkvaspace, 0, 157 "Kernel virtual memory used for buffers"); 158static long maxbufspace; 159SYSCTL_LONG(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RW, &maxbufspace, 0, 160 "Maximum allowed value of bufspace (including metadata)"); 161static long bufmallocspace; 162SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 163 "Amount of malloced memory for buffers"); 164static long maxbufmallocspace; 165SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 166 0, "Maximum amount of malloced memory for buffers"); 167static long lobufspace; 168SYSCTL_LONG(_vfs, OID_AUTO, lobufspace, CTLFLAG_RW, &lobufspace, 0, 169 "Minimum amount of buffers we want to have"); 170long hibufspace; 171SYSCTL_LONG(_vfs, OID_AUTO, hibufspace, CTLFLAG_RW, &hibufspace, 0, 172 "Maximum allowed value of bufspace (excluding metadata)"); 173long bufspacethresh; 174SYSCTL_LONG(_vfs, OID_AUTO, bufspacethresh, CTLFLAG_RW, &bufspacethresh, 175 0, "Bufspace consumed before waking the daemon to free some"); 176static int buffreekvacnt; 177SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0, 178 "Number of times we have freed the KVA space from some buffer"); 179static int bufdefragcnt; 180SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0, 181 "Number of times we have had to repeat buffer allocation to defragment"); 182static long lorunningspace; 183SYSCTL_PROC(_vfs, OID_AUTO, lorunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE | 184 CTLFLAG_RW, &lorunningspace, 0, sysctl_runningspace, "L", 185 "Minimum preferred space used for in-progress I/O"); 186static long hirunningspace; 187SYSCTL_PROC(_vfs, OID_AUTO, hirunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE | 188 CTLFLAG_RW, &hirunningspace, 0, sysctl_runningspace, "L", 189 "Maximum amount of space to use for in-progress I/O"); 190int dirtybufferflushes; 191SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes, 192 0, "Number of bdwrite to bawrite conversions to limit dirty buffers"); 193int bdwriteskip; 194SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip, 195 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk"); 196int altbufferflushes; 197SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes, 198 0, "Number of fsync flushes to limit dirty buffers"); 199static int recursiveflushes; 200SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes, 201 0, "Number of flushes skipped due to being recursive"); 202static int numdirtybuffers; 203SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0, 204 "Number of buffers that are dirty (has unwritten changes) at the moment"); 205static int lodirtybuffers; 206SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0, 207 "How many buffers we want to have free before bufdaemon can sleep"); 208static int hidirtybuffers; 209SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0, 210 "When the number of dirty buffers is considered severe"); 211int dirtybufthresh; 212SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh, 213 0, "Number of bdwrite to bawrite conversions to clear dirty buffers"); 214static int numfreebuffers; 215SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, 216 "Number of free buffers"); 217static int lofreebuffers; 218SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0, 219 "Target number of free buffers"); 220static int hifreebuffers; 221SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0, 222 "Threshold for clean buffer recycling"); 223static int getnewbufcalls; 224SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0, 225 "Number of calls to getnewbuf"); 226static int getnewbufrestarts; 227SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0, 228 "Number of times getnewbuf has had to restart a buffer acquisition"); 229static int mappingrestarts; 230SYSCTL_INT(_vfs, OID_AUTO, mappingrestarts, CTLFLAG_RW, &mappingrestarts, 0, 231 "Number of times getblk has had to restart a buffer mapping for " 232 "unmapped buffer"); 233static int numbufallocfails; 234SYSCTL_INT(_vfs, OID_AUTO, numbufallocfails, CTLFLAG_RW, &numbufallocfails, 0, 235 "Number of times buffer allocations failed"); 236static int flushbufqtarget = 100; 237SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0, 238 "Amount of work to do in flushbufqueues when helping bufdaemon"); 239static long notbufdflushes; 240SYSCTL_LONG(_vfs, OID_AUTO, notbufdflushes, CTLFLAG_RD, ¬bufdflushes, 0, 241 "Number of dirty buffer flushes done by the bufdaemon helpers"); 242static long barrierwrites; 243SYSCTL_LONG(_vfs, OID_AUTO, barrierwrites, CTLFLAG_RW, &barrierwrites, 0, 244 "Number of barrier writes"); 245SYSCTL_INT(_vfs, OID_AUTO, unmapped_buf_allowed, CTLFLAG_RD, 246 &unmapped_buf_allowed, 0, 247 "Permit the use of the unmapped i/o"); 248 249/* 250 * This lock synchronizes access to bd_request. 251 */ 252static struct mtx_padalign bdlock; 253 254/* 255 * This lock protects the runningbufreq and synchronizes runningbufwakeup and 256 * waitrunningbufspace(). 257 */ 258static struct mtx_padalign rbreqlock; 259 260/* 261 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it. 262 */ 263static struct rwlock_padalign nblock; 264 265/* 266 * Lock that protects bdirtywait. 267 */ 268static struct mtx_padalign bdirtylock; 269 270/* 271 * Wakeup point for bufdaemon, as well as indicator of whether it is already 272 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it 273 * is idling. 274 */ 275static int bd_request; 276 277/* 278 * Request/wakeup point for the bufspace daemon. 279 */ 280static int bufspace_request; 281 282/* 283 * Request for the buf daemon to write more buffers than is indicated by 284 * lodirtybuf. This may be necessary to push out excess dependencies or 285 * defragment the address space where a simple count of the number of dirty 286 * buffers is insufficient to characterize the demand for flushing them. 287 */ 288static int bd_speedupreq; 289 290/* 291 * bogus page -- for I/O to/from partially complete buffers 292 * this is a temporary solution to the problem, but it is not 293 * really that bad. it would be better to split the buffer 294 * for input in the case of buffers partially already in memory, 295 * but the code is intricate enough already. 296 */ 297vm_page_t bogus_page; 298 299/* 300 * Synchronization (sleep/wakeup) variable for active buffer space requests. 301 * Set when wait starts, cleared prior to wakeup(). 302 * Used in runningbufwakeup() and waitrunningbufspace(). 303 */ 304static int runningbufreq; 305 306/* 307 * Synchronization (sleep/wakeup) variable for buffer requests. 308 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done 309 * by and/or. 310 * Used in numdirtywakeup(), bufspace_wakeup(), bwillwrite(), 311 * getnewbuf(), and getblk(). 312 */ 313static volatile int needsbuffer; 314 315/* 316 * Synchronization for bwillwrite() waiters. 317 */ 318static int bdirtywait; 319 320/* 321 * Definitions for the buffer free lists. 322 */ 323#define QUEUE_NONE 0 /* on no queue */ 324#define QUEUE_EMPTY 1 /* empty buffer headers */ 325#define QUEUE_DIRTY 2 /* B_DELWRI buffers */ 326#define QUEUE_CLEAN 3 /* non-B_DELWRI buffers */ 327#define QUEUE_SENTINEL 1024 /* not an queue index, but mark for sentinel */ 328 329/* Maximum number of clean buffer queues. */ 330#define CLEAN_QUEUES 16 331 332/* Configured number of clean queues. */ 333static int clean_queues; 334 335/* Maximum number of buffer queues. */ 336#define BUFFER_QUEUES (QUEUE_CLEAN + CLEAN_QUEUES) 337 338/* Queues for free buffers with various properties */ 339static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } }; 340#ifdef INVARIANTS 341static int bq_len[BUFFER_QUEUES]; 342#endif 343 344/* 345 * Lock for each bufqueue 346 */ 347static struct mtx_padalign bqlocks[BUFFER_QUEUES]; 348 349/* 350 * per-cpu empty buffer cache. 351 */ 352uma_zone_t buf_zone; 353 354/* 355 * Single global constant for BUF_WMESG, to avoid getting multiple references. 356 * buf_wmesg is referred from macros. 357 */ 358const char *buf_wmesg = BUF_WMESG; 359 360static int 361sysctl_runningspace(SYSCTL_HANDLER_ARGS) 362{ 363 long value; 364 int error; 365 366 value = *(long *)arg1; 367 error = sysctl_handle_long(oidp, &value, 0, req); 368 if (error != 0 || req->newptr == NULL) 369 return (error); 370 mtx_lock(&rbreqlock); 371 if (arg1 == &hirunningspace) { 372 if (value < lorunningspace) 373 error = EINVAL; 374 else 375 hirunningspace = value; 376 } else { 377 KASSERT(arg1 == &lorunningspace, 378 ("%s: unknown arg1", __func__)); 379 if (value > hirunningspace) 380 error = EINVAL; 381 else 382 lorunningspace = value; 383 } 384 mtx_unlock(&rbreqlock); 385 return (error); 386} 387 388#if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 389 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 390static int 391sysctl_bufspace(SYSCTL_HANDLER_ARGS) 392{ 393 long lvalue; 394 int ivalue; 395 396 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long)) 397 return (sysctl_handle_long(oidp, arg1, arg2, req)); 398 lvalue = *(long *)arg1; 399 if (lvalue > INT_MAX) 400 /* On overflow, still write out a long to trigger ENOMEM. */ 401 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 402 ivalue = lvalue; 403 return (sysctl_handle_int(oidp, &ivalue, 0, req)); 404} 405#endif 406 407static int 408bqcleanq(void) 409{ 410 static int nextq; 411 412 return ((atomic_fetchadd_int(&nextq, 1) % clean_queues) + QUEUE_CLEAN); 413} 414 415static int 416bqisclean(int qindex) 417{ 418 419 return (qindex >= QUEUE_CLEAN && qindex < QUEUE_CLEAN + CLEAN_QUEUES); 420} 421 422/* 423 * bqlock: 424 * 425 * Return the appropriate queue lock based on the index. 426 */ 427static inline struct mtx * 428bqlock(int qindex) 429{ 430 431 return (struct mtx *)&bqlocks[qindex]; 432} 433 434/* 435 * bdirtywakeup: 436 * 437 * Wakeup any bwillwrite() waiters. 438 */ 439static void 440bdirtywakeup(void) 441{ 442 mtx_lock(&bdirtylock); 443 if (bdirtywait) { 444 bdirtywait = 0; 445 wakeup(&bdirtywait); 446 } 447 mtx_unlock(&bdirtylock); 448} 449 450/* 451 * bdirtysub: 452 * 453 * Decrement the numdirtybuffers count by one and wakeup any 454 * threads blocked in bwillwrite(). 455 */ 456static void 457bdirtysub(void) 458{ 459 460 if (atomic_fetchadd_int(&numdirtybuffers, -1) == 461 (lodirtybuffers + hidirtybuffers) / 2) 462 bdirtywakeup(); 463} 464 465/* 466 * bdirtyadd: 467 * 468 * Increment the numdirtybuffers count by one and wakeup the buf 469 * daemon if needed. 470 */ 471static void 472bdirtyadd(void) 473{ 474 475 /* 476 * Only do the wakeup once as we cross the boundary. The 477 * buf daemon will keep running until the condition clears. 478 */ 479 if (atomic_fetchadd_int(&numdirtybuffers, 1) == 480 (lodirtybuffers + hidirtybuffers) / 2) 481 bd_wakeup(); 482} 483 484/* 485 * bufspace_wakeup: 486 * 487 * Called when buffer space is potentially available for recovery. 488 * getnewbuf() will block on this flag when it is unable to free 489 * sufficient buffer space. Buffer space becomes recoverable when 490 * bp's get placed back in the queues. 491 */ 492static void 493bufspace_wakeup(void) 494{ 495 496 /* 497 * If someone is waiting for bufspace, wake them up. 498 * 499 * Since needsbuffer is set prior to doing an additional queue 500 * scan it is safe to check for the flag prior to acquiring the 501 * lock. The thread that is preparing to scan again before 502 * blocking would discover the buf we released. 503 */ 504 if (needsbuffer) { 505 rw_rlock(&nblock); 506 if (atomic_cmpset_int(&needsbuffer, 1, 0) == 1) 507 wakeup(__DEVOLATILE(void *, &needsbuffer)); 508 rw_runlock(&nblock); 509 } 510} 511 512/* 513 * bufspace_daemonwakeup: 514 * 515 * Wakeup the daemon responsible for freeing clean bufs. 516 */ 517static void 518bufspace_daemonwakeup(void) 519{ 520 rw_rlock(&nblock); 521 if (bufspace_request == 0) { 522 bufspace_request = 1; 523 wakeup(&bufspace_request); 524 } 525 rw_runlock(&nblock); 526} 527 528/* 529 * bufspace_adjust: 530 * 531 * Adjust the reported bufspace for a KVA managed buffer, possibly 532 * waking any waiters. 533 */ 534static void 535bufspace_adjust(struct buf *bp, int bufsize) 536{ 537 long space; 538 int diff; 539 540 KASSERT((bp->b_flags & B_MALLOC) == 0, 541 ("bufspace_adjust: malloc buf %p", bp)); 542 diff = bufsize - bp->b_bufsize; 543 if (diff < 0) { 544 atomic_subtract_long(&bufspace, -diff); 545 bufspace_wakeup(); 546 } else { 547 space = atomic_fetchadd_long(&bufspace, diff); 548 /* Wake up the daemon on the transition. */ 549 if (space < bufspacethresh && space + diff >= bufspacethresh) 550 bufspace_daemonwakeup(); 551 } 552 bp->b_bufsize = bufsize; 553} 554 555/* 556 * bufspace_reserve: 557 * 558 * Reserve bufspace before calling allocbuf(). metadata has a 559 * different space limit than data. 560 */ 561static int 562bufspace_reserve(int size, bool metadata) 563{ 564 long limit; 565 long space; 566 567 if (metadata) 568 limit = maxbufspace; 569 else 570 limit = hibufspace; 571 do { 572 space = bufspace; 573 if (space + size > limit) 574 return (ENOSPC); 575 } while (atomic_cmpset_long(&bufspace, space, space + size) == 0); 576 577 /* Wake up the daemon on the transition. */ 578 if (space < bufspacethresh && space + size >= bufspacethresh) 579 bufspace_daemonwakeup(); 580 581 return (0); 582} 583 584/* 585 * bufspace_release: 586 * 587 * Release reserved bufspace after bufspace_adjust() has consumed it. 588 */ 589static void 590bufspace_release(int size) 591{ 592 atomic_subtract_long(&bufspace, size); 593 bufspace_wakeup(); 594} 595 596/* 597 * bufspace_wait: 598 * 599 * Wait for bufspace, acting as the buf daemon if a locked vnode is 600 * supplied. needsbuffer must be set in a safe fashion prior to 601 * polling for space. The operation must be re-tried on return. 602 */ 603static void 604bufspace_wait(struct vnode *vp, int gbflags, int slpflag, int slptimeo) 605{ 606 struct thread *td; 607 int error, fl, norunbuf; 608 609 if ((gbflags & GB_NOWAIT_BD) != 0) 610 return; 611 612 td = curthread; 613 rw_wlock(&nblock); 614 while (needsbuffer != 0) { 615 if (vp != NULL && vp->v_type != VCHR && 616 (td->td_pflags & TDP_BUFNEED) == 0) { 617 rw_wunlock(&nblock); 618 /* 619 * getblk() is called with a vnode locked, and 620 * some majority of the dirty buffers may as 621 * well belong to the vnode. Flushing the 622 * buffers there would make a progress that 623 * cannot be achieved by the buf_daemon, that 624 * cannot lock the vnode. 625 */ 626 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) | 627 (td->td_pflags & TDP_NORUNNINGBUF); 628 629 /* 630 * Play bufdaemon. The getnewbuf() function 631 * may be called while the thread owns lock 632 * for another dirty buffer for the same 633 * vnode, which makes it impossible to use 634 * VOP_FSYNC() there, due to the buffer lock 635 * recursion. 636 */ 637 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF; 638 fl = buf_flush(vp, flushbufqtarget); 639 td->td_pflags &= norunbuf; 640 rw_wlock(&nblock); 641 if (fl != 0) 642 continue; 643 if (needsbuffer == 0) 644 break; 645 } 646 error = rw_sleep(__DEVOLATILE(void *, &needsbuffer), &nblock, 647 (PRIBIO + 4) | slpflag, "newbuf", slptimeo); 648 if (error != 0) 649 break; 650 } 651 rw_wunlock(&nblock); 652} 653 654 655/* 656 * bufspace_daemon: 657 * 658 * buffer space management daemon. Tries to maintain some marginal 659 * amount of free buffer space so that requesting processes neither 660 * block nor work to reclaim buffers. 661 */ 662static void 663bufspace_daemon(void) 664{ 665 for (;;) { 666 kproc_suspend_check(bufspacedaemonproc); 667 668 /* 669 * Free buffers from the clean queue until we meet our 670 * targets. 671 * 672 * Theory of operation: The buffer cache is most efficient 673 * when some free buffer headers and space are always 674 * available to getnewbuf(). This daemon attempts to prevent 675 * the excessive blocking and synchronization associated 676 * with shortfall. It goes through three phases according 677 * demand: 678 * 679 * 1) The daemon wakes up voluntarily once per-second 680 * during idle periods when the counters are below 681 * the wakeup thresholds (bufspacethresh, lofreebuffers). 682 * 683 * 2) The daemon wakes up as we cross the thresholds 684 * ahead of any potential blocking. This may bounce 685 * slightly according to the rate of consumption and 686 * release. 687 * 688 * 3) The daemon and consumers are starved for working 689 * clean buffers. This is the 'bufspace' sleep below 690 * which will inefficiently trade bufs with bqrelse 691 * until we return to condition 2. 692 */ 693 while (bufspace > lobufspace || 694 numfreebuffers < hifreebuffers) { 695 if (buf_recycle(false) != 0) { 696 atomic_set_int(&needsbuffer, 1); 697 if (buf_recycle(false) != 0) { 698 rw_wlock(&nblock); 699 if (needsbuffer) 700 rw_sleep(__DEVOLATILE(void *, 701 &needsbuffer), &nblock, 702 PRIBIO|PDROP, "bufspace", 703 hz/10); 704 else 705 rw_wunlock(&nblock); 706 } 707 } 708 maybe_yield(); 709 } 710 711 /* 712 * Re-check our limits under the exclusive nblock. 713 */ 714 rw_wlock(&nblock); 715 if (bufspace < bufspacethresh && 716 numfreebuffers > lofreebuffers) { 717 bufspace_request = 0; 718 rw_sleep(&bufspace_request, &nblock, PRIBIO|PDROP, 719 "-", hz); 720 } else 721 rw_wunlock(&nblock); 722 } 723} 724 725static struct kproc_desc bufspace_kp = { 726 "bufspacedaemon", 727 bufspace_daemon, 728 &bufspacedaemonproc 729}; 730SYSINIT(bufspacedaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, 731 &bufspace_kp); 732 733/* 734 * bufmallocadjust: 735 * 736 * Adjust the reported bufspace for a malloc managed buffer, possibly 737 * waking any waiters. 738 */ 739static void 740bufmallocadjust(struct buf *bp, int bufsize) 741{ 742 int diff; 743 744 KASSERT((bp->b_flags & B_MALLOC) != 0, 745 ("bufmallocadjust: non-malloc buf %p", bp)); 746 diff = bufsize - bp->b_bufsize; 747 if (diff < 0) 748 atomic_subtract_long(&bufmallocspace, -diff); 749 else 750 atomic_add_long(&bufmallocspace, diff); 751 bp->b_bufsize = bufsize; 752} 753 754/* 755 * runningwakeup: 756 * 757 * Wake up processes that are waiting on asynchronous writes to fall 758 * below lorunningspace. 759 */ 760static void 761runningwakeup(void) 762{ 763 764 mtx_lock(&rbreqlock); 765 if (runningbufreq) { 766 runningbufreq = 0; 767 wakeup(&runningbufreq); 768 } 769 mtx_unlock(&rbreqlock); 770} 771 772/* 773 * runningbufwakeup: 774 * 775 * Decrement the outstanding write count according. 776 */ 777void 778runningbufwakeup(struct buf *bp) 779{ 780 long space, bspace; 781 782 bspace = bp->b_runningbufspace; 783 if (bspace == 0) 784 return; 785 space = atomic_fetchadd_long(&runningbufspace, -bspace); 786 KASSERT(space >= bspace, ("runningbufspace underflow %ld %ld", 787 space, bspace)); 788 bp->b_runningbufspace = 0; 789 /* 790 * Only acquire the lock and wakeup on the transition from exceeding 791 * the threshold to falling below it. 792 */ 793 if (space < lorunningspace) 794 return; 795 if (space - bspace > lorunningspace) 796 return; 797 runningwakeup(); 798} 799 800/* 801 * waitrunningbufspace() 802 * 803 * runningbufspace is a measure of the amount of I/O currently 804 * running. This routine is used in async-write situations to 805 * prevent creating huge backups of pending writes to a device. 806 * Only asynchronous writes are governed by this function. 807 * 808 * This does NOT turn an async write into a sync write. It waits 809 * for earlier writes to complete and generally returns before the 810 * caller's write has reached the device. 811 */ 812void 813waitrunningbufspace(void) 814{ 815 816 mtx_lock(&rbreqlock); 817 while (runningbufspace > hirunningspace) { 818 runningbufreq = 1; 819 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 820 } 821 mtx_unlock(&rbreqlock); 822} 823 824 825/* 826 * vfs_buf_test_cache: 827 * 828 * Called when a buffer is extended. This function clears the B_CACHE 829 * bit if the newly extended portion of the buffer does not contain 830 * valid data. 831 */ 832static __inline void 833vfs_buf_test_cache(struct buf *bp, vm_ooffset_t foff, vm_offset_t off, 834 vm_offset_t size, vm_page_t m) 835{ 836 837 VM_OBJECT_ASSERT_LOCKED(m->object); 838 if (bp->b_flags & B_CACHE) { 839 int base = (foff + off) & PAGE_MASK; 840 if (vm_page_is_valid(m, base, size) == 0) 841 bp->b_flags &= ~B_CACHE; 842 } 843} 844 845/* Wake up the buffer daemon if necessary */ 846static __inline void 847bd_wakeup(void) 848{ 849 850 mtx_lock(&bdlock); 851 if (bd_request == 0) { 852 bd_request = 1; 853 wakeup(&bd_request); 854 } 855 mtx_unlock(&bdlock); 856} 857 858/* 859 * bd_speedup - speedup the buffer cache flushing code 860 */ 861void 862bd_speedup(void) 863{ 864 int needwake; 865 866 mtx_lock(&bdlock); 867 needwake = 0; 868 if (bd_speedupreq == 0 || bd_request == 0) 869 needwake = 1; 870 bd_speedupreq = 1; 871 bd_request = 1; 872 if (needwake) 873 wakeup(&bd_request); 874 mtx_unlock(&bdlock); 875} 876 877#ifndef NSWBUF_MIN 878#define NSWBUF_MIN 16 879#endif 880 881#ifdef __i386__ 882#define TRANSIENT_DENOM 5 883#else 884#define TRANSIENT_DENOM 10 885#endif 886 887/* 888 * Calculating buffer cache scaling values and reserve space for buffer 889 * headers. This is called during low level kernel initialization and 890 * may be called more then once. We CANNOT write to the memory area 891 * being reserved at this time. 892 */ 893caddr_t 894kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 895{ 896 int tuned_nbuf; 897 long maxbuf, maxbuf_sz, buf_sz, biotmap_sz; 898 899 /* 900 * physmem_est is in pages. Convert it to kilobytes (assumes 901 * PAGE_SIZE is >= 1K) 902 */ 903 physmem_est = physmem_est * (PAGE_SIZE / 1024); 904 905 /* 906 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 907 * For the first 64MB of ram nominally allocate sufficient buffers to 908 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 909 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing 910 * the buffer cache we limit the eventual kva reservation to 911 * maxbcache bytes. 912 * 913 * factor represents the 1/4 x ram conversion. 914 */ 915 if (nbuf == 0) { 916 int factor = 4 * BKVASIZE / 1024; 917 918 nbuf = 50; 919 if (physmem_est > 4096) 920 nbuf += min((physmem_est - 4096) / factor, 921 65536 / factor); 922 if (physmem_est > 65536) 923 nbuf += min((physmem_est - 65536) * 2 / (factor * 5), 924 32 * 1024 * 1024 / (factor * 5)); 925 926 if (maxbcache && nbuf > maxbcache / BKVASIZE) 927 nbuf = maxbcache / BKVASIZE; 928 tuned_nbuf = 1; 929 } else 930 tuned_nbuf = 0; 931 932 /* XXX Avoid unsigned long overflows later on with maxbufspace. */ 933 maxbuf = (LONG_MAX / 3) / BKVASIZE; 934 if (nbuf > maxbuf) { 935 if (!tuned_nbuf) 936 printf("Warning: nbufs lowered from %d to %ld\n", nbuf, 937 maxbuf); 938 nbuf = maxbuf; 939 } 940 941 /* 942 * Ideal allocation size for the transient bio submap is 10% 943 * of the maximal space buffer map. This roughly corresponds 944 * to the amount of the buffer mapped for typical UFS load. 945 * 946 * Clip the buffer map to reserve space for the transient 947 * BIOs, if its extent is bigger than 90% (80% on i386) of the 948 * maximum buffer map extent on the platform. 949 * 950 * The fall-back to the maxbuf in case of maxbcache unset, 951 * allows to not trim the buffer KVA for the architectures 952 * with ample KVA space. 953 */ 954 if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) { 955 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE; 956 buf_sz = (long)nbuf * BKVASIZE; 957 if (buf_sz < maxbuf_sz / TRANSIENT_DENOM * 958 (TRANSIENT_DENOM - 1)) { 959 /* 960 * There is more KVA than memory. Do not 961 * adjust buffer map size, and assign the rest 962 * of maxbuf to transient map. 963 */ 964 biotmap_sz = maxbuf_sz - buf_sz; 965 } else { 966 /* 967 * Buffer map spans all KVA we could afford on 968 * this platform. Give 10% (20% on i386) of 969 * the buffer map to the transient bio map. 970 */ 971 biotmap_sz = buf_sz / TRANSIENT_DENOM; 972 buf_sz -= biotmap_sz; 973 } 974 if (biotmap_sz / INT_MAX > MAXPHYS) 975 bio_transient_maxcnt = INT_MAX; 976 else 977 bio_transient_maxcnt = biotmap_sz / MAXPHYS; 978 /* 979 * Artificially limit to 1024 simultaneous in-flight I/Os 980 * using the transient mapping. 981 */ 982 if (bio_transient_maxcnt > 1024) 983 bio_transient_maxcnt = 1024; 984 if (tuned_nbuf) 985 nbuf = buf_sz / BKVASIZE; 986 } 987 988 /* 989 * swbufs are used as temporary holders for I/O, such as paging I/O. 990 * We have no less then 16 and no more then 256. 991 */ 992 nswbuf = min(nbuf / 4, 256); 993 TUNABLE_INT_FETCH("kern.nswbuf", &nswbuf); 994 if (nswbuf < NSWBUF_MIN) 995 nswbuf = NSWBUF_MIN; 996 997 /* 998 * Reserve space for the buffer cache buffers 999 */ 1000 swbuf = (void *)v; 1001 v = (caddr_t)(swbuf + nswbuf); 1002 buf = (void *)v; 1003 v = (caddr_t)(buf + nbuf); 1004 1005 return(v); 1006} 1007 1008/* Initialize the buffer subsystem. Called before use of any buffers. */ 1009void 1010bufinit(void) 1011{ 1012 struct buf *bp; 1013 int i; 1014 1015 CTASSERT(MAXBCACHEBUF >= MAXBSIZE); 1016 mtx_init(&bqlocks[QUEUE_DIRTY], "bufq dirty lock", NULL, MTX_DEF); 1017 mtx_init(&bqlocks[QUEUE_EMPTY], "bufq empty lock", NULL, MTX_DEF); 1018 for (i = QUEUE_CLEAN; i < QUEUE_CLEAN + CLEAN_QUEUES; i++) 1019 mtx_init(&bqlocks[i], "bufq clean lock", NULL, MTX_DEF); 1020 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 1021 rw_init(&nblock, "needsbuffer lock"); 1022 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 1023 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF); 1024 1025 /* next, make a null set of free lists */ 1026 for (i = 0; i < BUFFER_QUEUES; i++) 1027 TAILQ_INIT(&bufqueues[i]); 1028 1029 unmapped_buf = (caddr_t)kva_alloc(MAXPHYS); 1030 1031 /* finally, initialize each buffer header and stick on empty q */ 1032 for (i = 0; i < nbuf; i++) { 1033 bp = &buf[i]; 1034 bzero(bp, sizeof *bp); 1035 bp->b_flags = B_INVAL; 1036 bp->b_rcred = NOCRED; 1037 bp->b_wcred = NOCRED; 1038 bp->b_qindex = QUEUE_EMPTY; 1039 bp->b_xflags = 0; 1040 bp->b_data = bp->b_kvabase = unmapped_buf; 1041 LIST_INIT(&bp->b_dep); 1042 BUF_LOCKINIT(bp); 1043 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 1044#ifdef INVARIANTS 1045 bq_len[QUEUE_EMPTY]++; 1046#endif 1047 } 1048 1049 /* 1050 * maxbufspace is the absolute maximum amount of buffer space we are 1051 * allowed to reserve in KVM and in real terms. The absolute maximum 1052 * is nominally used by metadata. hibufspace is the nominal maximum 1053 * used by most other requests. The differential is required to 1054 * ensure that metadata deadlocks don't occur. 1055 * 1056 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 1057 * this may result in KVM fragmentation which is not handled optimally 1058 * by the system. XXX This is less true with vmem. We could use 1059 * PAGE_SIZE. 1060 */ 1061 maxbufspace = (long)nbuf * BKVASIZE; 1062 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - MAXBCACHEBUF * 10); 1063 lobufspace = (hibufspace / 20) * 19; /* 95% */ 1064 bufspacethresh = lobufspace + (hibufspace - lobufspace) / 2; 1065 1066 /* 1067 * Note: The 16 MiB upper limit for hirunningspace was chosen 1068 * arbitrarily and may need further tuning. It corresponds to 1069 * 128 outstanding write IO requests (if IO size is 128 KiB), 1070 * which fits with many RAID controllers' tagged queuing limits. 1071 * The lower 1 MiB limit is the historical upper limit for 1072 * hirunningspace. 1073 */ 1074 hirunningspace = lmax(lmin(roundup(hibufspace / 64, MAXBCACHEBUF), 1075 16 * 1024 * 1024), 1024 * 1024); 1076 lorunningspace = roundup((hirunningspace * 2) / 3, MAXBCACHEBUF); 1077 1078 /* 1079 * Limit the amount of malloc memory since it is wired permanently into 1080 * the kernel space. Even though this is accounted for in the buffer 1081 * allocation, we don't want the malloced region to grow uncontrolled. 1082 * The malloc scheme improves memory utilization significantly on 1083 * average (small) directories. 1084 */ 1085 maxbufmallocspace = hibufspace / 20; 1086 1087 /* 1088 * Reduce the chance of a deadlock occurring by limiting the number 1089 * of delayed-write dirty buffers we allow to stack up. 1090 */ 1091 hidirtybuffers = nbuf / 4 + 20; 1092 dirtybufthresh = hidirtybuffers * 9 / 10; 1093 numdirtybuffers = 0; 1094 /* 1095 * To support extreme low-memory systems, make sure hidirtybuffers 1096 * cannot eat up all available buffer space. This occurs when our 1097 * minimum cannot be met. We try to size hidirtybuffers to 3/4 our 1098 * buffer space assuming BKVASIZE'd buffers. 1099 */ 1100 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 1101 hidirtybuffers >>= 1; 1102 } 1103 lodirtybuffers = hidirtybuffers / 2; 1104 1105 /* 1106 * lofreebuffers should be sufficient to avoid stalling waiting on 1107 * buf headers under heavy utilization. The bufs in per-cpu caches 1108 * are counted as free but will be unavailable to threads executing 1109 * on other cpus. 1110 * 1111 * hifreebuffers is the free target for the bufspace daemon. This 1112 * should be set appropriately to limit work per-iteration. 1113 */ 1114 lofreebuffers = MIN((nbuf / 25) + (20 * mp_ncpus), 128 * mp_ncpus); 1115 hifreebuffers = (3 * lofreebuffers) / 2; 1116 numfreebuffers = nbuf; 1117 1118 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ | 1119 VM_ALLOC_NORMAL | VM_ALLOC_WIRED); 1120 1121 /* Setup the kva and free list allocators. */ 1122 vmem_set_reclaim(buffer_arena, bufkva_reclaim); 1123 buf_zone = uma_zcache_create("buf free cache", sizeof(struct buf), 1124 NULL, NULL, NULL, NULL, buf_import, buf_release, NULL, 0); 1125 1126 /* 1127 * Size the clean queue according to the amount of buffer space. 1128 * One queue per-256mb up to the max. More queues gives better 1129 * concurrency but less accurate LRU. 1130 */ 1131 clean_queues = MIN(howmany(maxbufspace, 256*1024*1024), CLEAN_QUEUES); 1132 1133} 1134 1135#ifdef INVARIANTS 1136static inline void 1137vfs_buf_check_mapped(struct buf *bp) 1138{ 1139 1140 KASSERT(bp->b_kvabase != unmapped_buf, 1141 ("mapped buf: b_kvabase was not updated %p", bp)); 1142 KASSERT(bp->b_data != unmapped_buf, 1143 ("mapped buf: b_data was not updated %p", bp)); 1144 KASSERT(bp->b_data < unmapped_buf || bp->b_data >= unmapped_buf + 1145 MAXPHYS, ("b_data + b_offset unmapped %p", bp)); 1146} 1147 1148static inline void 1149vfs_buf_check_unmapped(struct buf *bp) 1150{ 1151 1152 KASSERT(bp->b_data == unmapped_buf, 1153 ("unmapped buf: corrupted b_data %p", bp)); 1154} 1155 1156#define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp) 1157#define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp) 1158#else 1159#define BUF_CHECK_MAPPED(bp) do {} while (0) 1160#define BUF_CHECK_UNMAPPED(bp) do {} while (0) 1161#endif 1162 1163static int 1164isbufbusy(struct buf *bp) 1165{ 1166 if (((bp->b_flags & B_INVAL) == 0 && BUF_ISLOCKED(bp)) || 1167 ((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI)) 1168 return (1); 1169 return (0); 1170} 1171 1172/* 1173 * Shutdown the system cleanly to prepare for reboot, halt, or power off. 1174 */ 1175void 1176bufshutdown(int show_busybufs) 1177{ 1178 static int first_buf_printf = 1; 1179 struct buf *bp; 1180 int iter, nbusy, pbusy; 1181#ifndef PREEMPTION 1182 int subiter; 1183#endif 1184 1185 /* 1186 * Sync filesystems for shutdown 1187 */ 1188 wdog_kern_pat(WD_LASTVAL); 1189 sys_sync(curthread, NULL); 1190 1191 /* 1192 * With soft updates, some buffers that are 1193 * written will be remarked as dirty until other 1194 * buffers are written. 1195 */ 1196 for (iter = pbusy = 0; iter < 20; iter++) { 1197 nbusy = 0; 1198 for (bp = &buf[nbuf]; --bp >= buf; ) 1199 if (isbufbusy(bp)) 1200 nbusy++; 1201 if (nbusy == 0) { 1202 if (first_buf_printf) 1203 printf("All buffers synced."); 1204 break; 1205 } 1206 if (first_buf_printf) { 1207 printf("Syncing disks, buffers remaining... "); 1208 first_buf_printf = 0; 1209 } 1210 printf("%d ", nbusy); 1211 if (nbusy < pbusy) 1212 iter = 0; 1213 pbusy = nbusy; 1214 1215 wdog_kern_pat(WD_LASTVAL); 1216 sys_sync(curthread, NULL); 1217 1218#ifdef PREEMPTION 1219 /* 1220 * Drop Giant and spin for a while to allow 1221 * interrupt threads to run. 1222 */ 1223 DROP_GIANT(); 1224 DELAY(50000 * iter); 1225 PICKUP_GIANT(); 1226#else 1227 /* 1228 * Drop Giant and context switch several times to 1229 * allow interrupt threads to run. 1230 */ 1231 DROP_GIANT(); 1232 for (subiter = 0; subiter < 50 * iter; subiter++) { 1233 thread_lock(curthread); 1234 mi_switch(SW_VOL, NULL); 1235 thread_unlock(curthread); 1236 DELAY(1000); 1237 } 1238 PICKUP_GIANT(); 1239#endif 1240 } 1241 printf("\n"); 1242 /* 1243 * Count only busy local buffers to prevent forcing 1244 * a fsck if we're just a client of a wedged NFS server 1245 */ 1246 nbusy = 0; 1247 for (bp = &buf[nbuf]; --bp >= buf; ) { 1248 if (isbufbusy(bp)) { 1249#if 0 1250/* XXX: This is bogus. We should probably have a BO_REMOTE flag instead */ 1251 if (bp->b_dev == NULL) { 1252 TAILQ_REMOVE(&mountlist, 1253 bp->b_vp->v_mount, mnt_list); 1254 continue; 1255 } 1256#endif 1257 nbusy++; 1258 if (show_busybufs > 0) { 1259 printf( 1260 "%d: buf:%p, vnode:%p, flags:%0x, blkno:%jd, lblkno:%jd, buflock:", 1261 nbusy, bp, bp->b_vp, bp->b_flags, 1262 (intmax_t)bp->b_blkno, 1263 (intmax_t)bp->b_lblkno); 1264 BUF_LOCKPRINTINFO(bp); 1265 if (show_busybufs > 1) 1266 vn_printf(bp->b_vp, 1267 "vnode content: "); 1268 } 1269 } 1270 } 1271 if (nbusy) { 1272 /* 1273 * Failed to sync all blocks. Indicate this and don't 1274 * unmount filesystems (thus forcing an fsck on reboot). 1275 */ 1276 printf("Giving up on %d buffers\n", nbusy); 1277 DELAY(5000000); /* 5 seconds */ 1278 } else { 1279 if (!first_buf_printf) 1280 printf("Final sync complete\n"); 1281 /* 1282 * Unmount filesystems 1283 */ 1284 if (panicstr == NULL) 1285 vfs_unmountall(); 1286 } 1287 swapoff_all(); 1288 DELAY(100000); /* wait for console output to finish */ 1289} 1290 1291static void 1292bpmap_qenter(struct buf *bp) 1293{ 1294 1295 BUF_CHECK_MAPPED(bp); 1296 1297 /* 1298 * bp->b_data is relative to bp->b_offset, but 1299 * bp->b_offset may be offset into the first page. 1300 */ 1301 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data); 1302 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages); 1303 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 1304 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 1305} 1306 1307/* 1308 * binsfree: 1309 * 1310 * Insert the buffer into the appropriate free list. 1311 */ 1312static void 1313binsfree(struct buf *bp, int qindex) 1314{ 1315 struct mtx *olock, *nlock; 1316 1317 if (qindex != QUEUE_EMPTY) { 1318 BUF_ASSERT_XLOCKED(bp); 1319 } 1320 1321 /* 1322 * Stick to the same clean queue for the lifetime of the buf to 1323 * limit locking below. Otherwise pick ont sequentially. 1324 */ 1325 if (qindex == QUEUE_CLEAN) { 1326 if (bqisclean(bp->b_qindex)) 1327 qindex = bp->b_qindex; 1328 else 1329 qindex = bqcleanq(); 1330 } 1331 1332 /* 1333 * Handle delayed bremfree() processing. 1334 */ 1335 nlock = bqlock(qindex); 1336 if (bp->b_flags & B_REMFREE) { 1337 olock = bqlock(bp->b_qindex); 1338 mtx_lock(olock); 1339 bremfreel(bp); 1340 if (olock != nlock) { 1341 mtx_unlock(olock); 1342 mtx_lock(nlock); 1343 } 1344 } else 1345 mtx_lock(nlock); 1346 1347 if (bp->b_qindex != QUEUE_NONE) 1348 panic("binsfree: free buffer onto another queue???"); 1349 1350 bp->b_qindex = qindex; 1351 if (bp->b_flags & B_AGE) 1352 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1353 else 1354 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1355#ifdef INVARIANTS 1356 bq_len[bp->b_qindex]++; 1357#endif 1358 mtx_unlock(nlock); 1359} 1360 1361/* 1362 * buf_free: 1363 * 1364 * Free a buffer to the buf zone once it no longer has valid contents. 1365 */ 1366static void 1367buf_free(struct buf *bp) 1368{ 1369 1370 if (bp->b_flags & B_REMFREE) 1371 bremfreef(bp); 1372 if (bp->b_vflags & BV_BKGRDINPROG) 1373 panic("losing buffer 1"); 1374 if (bp->b_rcred != NOCRED) { 1375 crfree(bp->b_rcred); 1376 bp->b_rcred = NOCRED; 1377 } 1378 if (bp->b_wcred != NOCRED) { 1379 crfree(bp->b_wcred); 1380 bp->b_wcred = NOCRED; 1381 } 1382 if (!LIST_EMPTY(&bp->b_dep)) 1383 buf_deallocate(bp); 1384 bufkva_free(bp); 1385 BUF_UNLOCK(bp); 1386 uma_zfree(buf_zone, bp); 1387 atomic_add_int(&numfreebuffers, 1); 1388 bufspace_wakeup(); 1389} 1390 1391/* 1392 * buf_import: 1393 * 1394 * Import bufs into the uma cache from the buf list. The system still 1395 * expects a static array of bufs and much of the synchronization 1396 * around bufs assumes type stable storage. As a result, UMA is used 1397 * only as a per-cpu cache of bufs still maintained on a global list. 1398 */ 1399static int 1400buf_import(void *arg, void **store, int cnt, int flags) 1401{ 1402 struct buf *bp; 1403 int i; 1404 1405 mtx_lock(&bqlocks[QUEUE_EMPTY]); 1406 for (i = 0; i < cnt; i++) { 1407 bp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1408 if (bp == NULL) 1409 break; 1410 bremfreel(bp); 1411 store[i] = bp; 1412 } 1413 mtx_unlock(&bqlocks[QUEUE_EMPTY]); 1414 1415 return (i); 1416} 1417 1418/* 1419 * buf_release: 1420 * 1421 * Release bufs from the uma cache back to the buffer queues. 1422 */ 1423static void 1424buf_release(void *arg, void **store, int cnt) 1425{ 1426 int i; 1427 1428 for (i = 0; i < cnt; i++) 1429 binsfree(store[i], QUEUE_EMPTY); 1430} 1431 1432/* 1433 * buf_alloc: 1434 * 1435 * Allocate an empty buffer header. 1436 */ 1437static struct buf * 1438buf_alloc(void) 1439{ 1440 struct buf *bp; 1441 1442 bp = uma_zalloc(buf_zone, M_NOWAIT); 1443 if (bp == NULL) { 1444 bufspace_daemonwakeup(); 1445 atomic_add_int(&numbufallocfails, 1); 1446 return (NULL); 1447 } 1448 1449 /* 1450 * Wake-up the bufspace daemon on transition. 1451 */ 1452 if (atomic_fetchadd_int(&numfreebuffers, -1) == lofreebuffers) 1453 bufspace_daemonwakeup(); 1454 1455 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1456 panic("getnewbuf_empty: Locked buf %p on free queue.", bp); 1457 1458 KASSERT(bp->b_vp == NULL, 1459 ("bp: %p still has vnode %p.", bp, bp->b_vp)); 1460 KASSERT((bp->b_flags & (B_DELWRI | B_NOREUSE)) == 0, 1461 ("invalid buffer %p flags %#x", bp, bp->b_flags)); 1462 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 1463 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags)); 1464 KASSERT(bp->b_npages == 0, 1465 ("bp: %p still has %d vm pages\n", bp, bp->b_npages)); 1466 KASSERT(bp->b_kvasize == 0, ("bp: %p still has kva\n", bp)); 1467 KASSERT(bp->b_bufsize == 0, ("bp: %p still has bufspace\n", bp)); 1468 1469 bp->b_flags = 0; 1470 bp->b_ioflags = 0; 1471 bp->b_xflags = 0; 1472 bp->b_vflags = 0; 1473 bp->b_vp = NULL; 1474 bp->b_blkno = bp->b_lblkno = 0; 1475 bp->b_offset = NOOFFSET; 1476 bp->b_iodone = 0; 1477 bp->b_error = 0; 1478 bp->b_resid = 0; 1479 bp->b_bcount = 0; 1480 bp->b_npages = 0; 1481 bp->b_dirtyoff = bp->b_dirtyend = 0; 1482 bp->b_bufobj = NULL; 1483 bp->b_pin_count = 0; 1484 bp->b_data = bp->b_kvabase = unmapped_buf; 1485 bp->b_fsprivate1 = NULL; 1486 bp->b_fsprivate2 = NULL; 1487 bp->b_fsprivate3 = NULL; 1488 LIST_INIT(&bp->b_dep); 1489 1490 return (bp); 1491} 1492 1493/* 1494 * buf_qrecycle: 1495 * 1496 * Free a buffer from the given bufqueue. kva controls whether the 1497 * freed buf must own some kva resources. This is used for 1498 * defragmenting. 1499 */ 1500static int 1501buf_qrecycle(int qindex, bool kva) 1502{ 1503 struct buf *bp, *nbp; 1504 1505 if (kva) 1506 atomic_add_int(&bufdefragcnt, 1); 1507 nbp = NULL; 1508 mtx_lock(&bqlocks[qindex]); 1509 nbp = TAILQ_FIRST(&bufqueues[qindex]); 1510 1511 /* 1512 * Run scan, possibly freeing data and/or kva mappings on the fly 1513 * depending. 1514 */ 1515 while ((bp = nbp) != NULL) { 1516 /* 1517 * Calculate next bp (we can only use it if we do not 1518 * release the bqlock). 1519 */ 1520 nbp = TAILQ_NEXT(bp, b_freelist); 1521 1522 /* 1523 * If we are defragging then we need a buffer with 1524 * some kva to reclaim. 1525 */ 1526 if (kva && bp->b_kvasize == 0) 1527 continue; 1528 1529 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1530 continue; 1531 1532 /* 1533 * Skip buffers with background writes in progress. 1534 */ 1535 if ((bp->b_vflags & BV_BKGRDINPROG) != 0) { 1536 BUF_UNLOCK(bp); 1537 continue; 1538 } 1539 1540 KASSERT(bp->b_qindex == qindex, 1541 ("getnewbuf: inconsistent queue %d bp %p", qindex, bp)); 1542 /* 1543 * NOTE: nbp is now entirely invalid. We can only restart 1544 * the scan from this point on. 1545 */ 1546 bremfreel(bp); 1547 mtx_unlock(&bqlocks[qindex]); 1548 1549 /* 1550 * Requeue the background write buffer with error and 1551 * restart the scan. 1552 */ 1553 if ((bp->b_vflags & BV_BKGRDERR) != 0) { 1554 bqrelse(bp); 1555 mtx_lock(&bqlocks[qindex]); 1556 nbp = TAILQ_FIRST(&bufqueues[qindex]); 1557 continue; 1558 } 1559 bp->b_flags |= B_INVAL; 1560 brelse(bp); 1561 return (0); 1562 } 1563 mtx_unlock(&bqlocks[qindex]); 1564 1565 return (ENOBUFS); 1566} 1567 1568/* 1569 * buf_recycle: 1570 * 1571 * Iterate through all clean queues until we find a buf to recycle or 1572 * exhaust the search. 1573 */ 1574static int 1575buf_recycle(bool kva) 1576{ 1577 int qindex, first_qindex; 1578 1579 qindex = first_qindex = bqcleanq(); 1580 do { 1581 if (buf_qrecycle(qindex, kva) == 0) 1582 return (0); 1583 if (++qindex == QUEUE_CLEAN + clean_queues) 1584 qindex = QUEUE_CLEAN; 1585 } while (qindex != first_qindex); 1586 1587 return (ENOBUFS); 1588} 1589 1590/* 1591 * buf_scan: 1592 * 1593 * Scan the clean queues looking for a buffer to recycle. needsbuffer 1594 * is set on failure so that the caller may optionally bufspace_wait() 1595 * in a race-free fashion. 1596 */ 1597static int 1598buf_scan(bool defrag) 1599{ 1600 int error; 1601 1602 /* 1603 * To avoid heavy synchronization and wakeup races we set 1604 * needsbuffer and re-poll before failing. This ensures that 1605 * no frees can be missed between an unsuccessful poll and 1606 * going to sleep in a synchronized fashion. 1607 */ 1608 if ((error = buf_recycle(defrag)) != 0) { 1609 atomic_set_int(&needsbuffer, 1); 1610 bufspace_daemonwakeup(); 1611 error = buf_recycle(defrag); 1612 } 1613 if (error == 0) 1614 atomic_add_int(&getnewbufrestarts, 1); 1615 return (error); 1616} 1617 1618/* 1619 * bremfree: 1620 * 1621 * Mark the buffer for removal from the appropriate free list. 1622 * 1623 */ 1624void 1625bremfree(struct buf *bp) 1626{ 1627 1628 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1629 KASSERT((bp->b_flags & B_REMFREE) == 0, 1630 ("bremfree: buffer %p already marked for delayed removal.", bp)); 1631 KASSERT(bp->b_qindex != QUEUE_NONE, 1632 ("bremfree: buffer %p not on a queue.", bp)); 1633 BUF_ASSERT_XLOCKED(bp); 1634 1635 bp->b_flags |= B_REMFREE; 1636} 1637 1638/* 1639 * bremfreef: 1640 * 1641 * Force an immediate removal from a free list. Used only in nfs when 1642 * it abuses the b_freelist pointer. 1643 */ 1644void 1645bremfreef(struct buf *bp) 1646{ 1647 struct mtx *qlock; 1648 1649 qlock = bqlock(bp->b_qindex); 1650 mtx_lock(qlock); 1651 bremfreel(bp); 1652 mtx_unlock(qlock); 1653} 1654 1655/* 1656 * bremfreel: 1657 * 1658 * Removes a buffer from the free list, must be called with the 1659 * correct qlock held. 1660 */ 1661static void 1662bremfreel(struct buf *bp) 1663{ 1664 1665 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X", 1666 bp, bp->b_vp, bp->b_flags); 1667 KASSERT(bp->b_qindex != QUEUE_NONE, 1668 ("bremfreel: buffer %p not on a queue.", bp)); 1669 if (bp->b_qindex != QUEUE_EMPTY) { 1670 BUF_ASSERT_XLOCKED(bp); 1671 } 1672 mtx_assert(bqlock(bp->b_qindex), MA_OWNED); 1673 1674 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 1675#ifdef INVARIANTS 1676 KASSERT(bq_len[bp->b_qindex] >= 1, ("queue %d underflow", 1677 bp->b_qindex)); 1678 bq_len[bp->b_qindex]--; 1679#endif 1680 bp->b_qindex = QUEUE_NONE; 1681 bp->b_flags &= ~B_REMFREE; 1682} 1683 1684/* 1685 * bufkva_free: 1686 * 1687 * Free the kva allocation for a buffer. 1688 * 1689 */ 1690static void 1691bufkva_free(struct buf *bp) 1692{ 1693 1694#ifdef INVARIANTS 1695 if (bp->b_kvasize == 0) { 1696 KASSERT(bp->b_kvabase == unmapped_buf && 1697 bp->b_data == unmapped_buf, 1698 ("Leaked KVA space on %p", bp)); 1699 } else if (buf_mapped(bp)) 1700 BUF_CHECK_MAPPED(bp); 1701 else 1702 BUF_CHECK_UNMAPPED(bp); 1703#endif 1704 if (bp->b_kvasize == 0) 1705 return; 1706 1707 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, bp->b_kvasize); 1708 atomic_subtract_long(&bufkvaspace, bp->b_kvasize); 1709 atomic_add_int(&buffreekvacnt, 1); 1710 bp->b_data = bp->b_kvabase = unmapped_buf; 1711 bp->b_kvasize = 0; 1712} 1713 1714/* 1715 * bufkva_alloc: 1716 * 1717 * Allocate the buffer KVA and set b_kvasize and b_kvabase. 1718 */ 1719static int 1720bufkva_alloc(struct buf *bp, int maxsize, int gbflags) 1721{ 1722 vm_offset_t addr; 1723 int error; 1724 1725 KASSERT((gbflags & GB_UNMAPPED) == 0 || (gbflags & GB_KVAALLOC) != 0, 1726 ("Invalid gbflags 0x%x in %s", gbflags, __func__)); 1727 1728 bufkva_free(bp); 1729 1730 addr = 0; 1731 error = vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr); 1732 if (error != 0) { 1733 /* 1734 * Buffer map is too fragmented. Request the caller 1735 * to defragment the map. 1736 */ 1737 return (error); 1738 } 1739 bp->b_kvabase = (caddr_t)addr; 1740 bp->b_kvasize = maxsize; 1741 atomic_add_long(&bufkvaspace, bp->b_kvasize); 1742 if ((gbflags & GB_UNMAPPED) != 0) { 1743 bp->b_data = unmapped_buf; 1744 BUF_CHECK_UNMAPPED(bp); 1745 } else { 1746 bp->b_data = bp->b_kvabase; 1747 BUF_CHECK_MAPPED(bp); 1748 } 1749 return (0); 1750} 1751 1752/* 1753 * bufkva_reclaim: 1754 * 1755 * Reclaim buffer kva by freeing buffers holding kva. This is a vmem 1756 * callback that fires to avoid returning failure. 1757 */ 1758static void 1759bufkva_reclaim(vmem_t *vmem, int flags) 1760{ 1761 int i; 1762 1763 for (i = 0; i < 5; i++) 1764 if (buf_scan(true) != 0) 1765 break; 1766 return; 1767} 1768 1769 1770/* 1771 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 1772 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 1773 * the buffer is valid and we do not have to do anything. 1774 */ 1775void 1776breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, 1777 int cnt, struct ucred * cred) 1778{ 1779 struct buf *rabp; 1780 int i; 1781 1782 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 1783 if (inmem(vp, *rablkno)) 1784 continue; 1785 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 1786 1787 if ((rabp->b_flags & B_CACHE) == 0) { 1788 if (!TD_IS_IDLETHREAD(curthread)) { 1789#ifdef RACCT 1790 if (racct_enable) { 1791 PROC_LOCK(curproc); 1792 racct_add_buf(curproc, rabp, 0); 1793 PROC_UNLOCK(curproc); 1794 } 1795#endif /* RACCT */ 1796 curthread->td_ru.ru_inblock++; 1797 } 1798 rabp->b_flags |= B_ASYNC; 1799 rabp->b_flags &= ~B_INVAL; 1800 rabp->b_ioflags &= ~BIO_ERROR; 1801 rabp->b_iocmd = BIO_READ; 1802 if (rabp->b_rcred == NOCRED && cred != NOCRED) 1803 rabp->b_rcred = crhold(cred); 1804 vfs_busy_pages(rabp, 0); 1805 BUF_KERNPROC(rabp); 1806 rabp->b_iooffset = dbtob(rabp->b_blkno); 1807 bstrategy(rabp); 1808 } else { 1809 brelse(rabp); 1810 } 1811 } 1812} 1813 1814/* 1815 * Entry point for bread() and breadn() via #defines in sys/buf.h. 1816 * 1817 * Get a buffer with the specified data. Look in the cache first. We 1818 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 1819 * is set, the buffer is valid and we do not have to do anything, see 1820 * getblk(). Also starts asynchronous I/O on read-ahead blocks. 1821 * 1822 * Always return a NULL buffer pointer (in bpp) when returning an error. 1823 */ 1824int 1825breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno, 1826 int *rabsize, int cnt, struct ucred *cred, int flags, struct buf **bpp) 1827{ 1828 struct buf *bp; 1829 int rv = 0, readwait = 0; 1830 1831 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 1832 /* 1833 * Can only return NULL if GB_LOCK_NOWAIT flag is specified. 1834 */ 1835 *bpp = bp = getblk(vp, blkno, size, 0, 0, flags); 1836 if (bp == NULL) 1837 return (EBUSY); 1838 1839 /* if not found in cache, do some I/O */ 1840 if ((bp->b_flags & B_CACHE) == 0) { 1841 if (!TD_IS_IDLETHREAD(curthread)) { 1842#ifdef RACCT 1843 if (racct_enable) { 1844 PROC_LOCK(curproc); 1845 racct_add_buf(curproc, bp, 0); 1846 PROC_UNLOCK(curproc); 1847 } 1848#endif /* RACCT */ 1849 curthread->td_ru.ru_inblock++; 1850 } 1851 bp->b_iocmd = BIO_READ; 1852 bp->b_flags &= ~B_INVAL; 1853 bp->b_ioflags &= ~BIO_ERROR; 1854 if (bp->b_rcred == NOCRED && cred != NOCRED) 1855 bp->b_rcred = crhold(cred); 1856 vfs_busy_pages(bp, 0); 1857 bp->b_iooffset = dbtob(bp->b_blkno); 1858 bstrategy(bp); 1859 ++readwait; 1860 } 1861 1862 breada(vp, rablkno, rabsize, cnt, cred); 1863 1864 if (readwait) { 1865 rv = bufwait(bp); 1866 if (rv != 0) { 1867 brelse(bp); 1868 *bpp = NULL; 1869 } 1870 } 1871 return (rv); 1872} 1873 1874/* 1875 * Write, release buffer on completion. (Done by iodone 1876 * if async). Do not bother writing anything if the buffer 1877 * is invalid. 1878 * 1879 * Note that we set B_CACHE here, indicating that buffer is 1880 * fully valid and thus cacheable. This is true even of NFS 1881 * now so we set it generally. This could be set either here 1882 * or in biodone() since the I/O is synchronous. We put it 1883 * here. 1884 */ 1885int 1886bufwrite(struct buf *bp) 1887{ 1888 int oldflags; 1889 struct vnode *vp; 1890 long space; 1891 int vp_md; 1892 1893 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1894 if ((bp->b_bufobj->bo_flag & BO_DEAD) != 0) { 1895 bp->b_flags |= B_INVAL | B_RELBUF; 1896 bp->b_flags &= ~B_CACHE; 1897 brelse(bp); 1898 return (ENXIO); 1899 } 1900 if (bp->b_flags & B_INVAL) { 1901 brelse(bp); 1902 return (0); 1903 } 1904 1905 if (bp->b_flags & B_BARRIER) 1906 barrierwrites++; 1907 1908 oldflags = bp->b_flags; 1909 1910 BUF_ASSERT_HELD(bp); 1911 1912 if (bp->b_pin_count > 0) 1913 bunpin_wait(bp); 1914 1915 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 1916 ("FFS background buffer should not get here %p", bp)); 1917 1918 vp = bp->b_vp; 1919 if (vp) 1920 vp_md = vp->v_vflag & VV_MD; 1921 else 1922 vp_md = 0; 1923 1924 /* 1925 * Mark the buffer clean. Increment the bufobj write count 1926 * before bundirty() call, to prevent other thread from seeing 1927 * empty dirty list and zero counter for writes in progress, 1928 * falsely indicating that the bufobj is clean. 1929 */ 1930 bufobj_wref(bp->b_bufobj); 1931 bundirty(bp); 1932 1933 bp->b_flags &= ~B_DONE; 1934 bp->b_ioflags &= ~BIO_ERROR; 1935 bp->b_flags |= B_CACHE; 1936 bp->b_iocmd = BIO_WRITE; 1937 1938 vfs_busy_pages(bp, 1); 1939 1940 /* 1941 * Normal bwrites pipeline writes 1942 */ 1943 bp->b_runningbufspace = bp->b_bufsize; 1944 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace); 1945 1946 if (!TD_IS_IDLETHREAD(curthread)) { 1947#ifdef RACCT 1948 if (racct_enable) { 1949 PROC_LOCK(curproc); 1950 racct_add_buf(curproc, bp, 1); 1951 PROC_UNLOCK(curproc); 1952 } 1953#endif /* RACCT */ 1954 curthread->td_ru.ru_oublock++; 1955 } 1956 if (oldflags & B_ASYNC) 1957 BUF_KERNPROC(bp); 1958 bp->b_iooffset = dbtob(bp->b_blkno); 1959 bstrategy(bp); 1960 1961 if ((oldflags & B_ASYNC) == 0) { 1962 int rtval = bufwait(bp); 1963 brelse(bp); 1964 return (rtval); 1965 } else if (space > hirunningspace) { 1966 /* 1967 * don't allow the async write to saturate the I/O 1968 * system. We will not deadlock here because 1969 * we are blocking waiting for I/O that is already in-progress 1970 * to complete. We do not block here if it is the update 1971 * or syncer daemon trying to clean up as that can lead 1972 * to deadlock. 1973 */ 1974 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 1975 waitrunningbufspace(); 1976 } 1977 1978 return (0); 1979} 1980 1981void 1982bufbdflush(struct bufobj *bo, struct buf *bp) 1983{ 1984 struct buf *nbp; 1985 1986 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 1987 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 1988 altbufferflushes++; 1989 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 1990 BO_LOCK(bo); 1991 /* 1992 * Try to find a buffer to flush. 1993 */ 1994 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 1995 if ((nbp->b_vflags & BV_BKGRDINPROG) || 1996 BUF_LOCK(nbp, 1997 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 1998 continue; 1999 if (bp == nbp) 2000 panic("bdwrite: found ourselves"); 2001 BO_UNLOCK(bo); 2002 /* Don't countdeps with the bo lock held. */ 2003 if (buf_countdeps(nbp, 0)) { 2004 BO_LOCK(bo); 2005 BUF_UNLOCK(nbp); 2006 continue; 2007 } 2008 if (nbp->b_flags & B_CLUSTEROK) { 2009 vfs_bio_awrite(nbp); 2010 } else { 2011 bremfree(nbp); 2012 bawrite(nbp); 2013 } 2014 dirtybufferflushes++; 2015 break; 2016 } 2017 if (nbp == NULL) 2018 BO_UNLOCK(bo); 2019 } 2020} 2021 2022/* 2023 * Delayed write. (Buffer is marked dirty). Do not bother writing 2024 * anything if the buffer is marked invalid. 2025 * 2026 * Note that since the buffer must be completely valid, we can safely 2027 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 2028 * biodone() in order to prevent getblk from writing the buffer 2029 * out synchronously. 2030 */ 2031void 2032bdwrite(struct buf *bp) 2033{ 2034 struct thread *td = curthread; 2035 struct vnode *vp; 2036 struct bufobj *bo; 2037 2038 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2039 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2040 KASSERT((bp->b_flags & B_BARRIER) == 0, 2041 ("Barrier request in delayed write %p", bp)); 2042 BUF_ASSERT_HELD(bp); 2043 2044 if (bp->b_flags & B_INVAL) { 2045 brelse(bp); 2046 return; 2047 } 2048 2049 /* 2050 * If we have too many dirty buffers, don't create any more. 2051 * If we are wildly over our limit, then force a complete 2052 * cleanup. Otherwise, just keep the situation from getting 2053 * out of control. Note that we have to avoid a recursive 2054 * disaster and not try to clean up after our own cleanup! 2055 */ 2056 vp = bp->b_vp; 2057 bo = bp->b_bufobj; 2058 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 2059 td->td_pflags |= TDP_INBDFLUSH; 2060 BO_BDFLUSH(bo, bp); 2061 td->td_pflags &= ~TDP_INBDFLUSH; 2062 } else 2063 recursiveflushes++; 2064 2065 bdirty(bp); 2066 /* 2067 * Set B_CACHE, indicating that the buffer is fully valid. This is 2068 * true even of NFS now. 2069 */ 2070 bp->b_flags |= B_CACHE; 2071 2072 /* 2073 * This bmap keeps the system from needing to do the bmap later, 2074 * perhaps when the system is attempting to do a sync. Since it 2075 * is likely that the indirect block -- or whatever other datastructure 2076 * that the filesystem needs is still in memory now, it is a good 2077 * thing to do this. Note also, that if the pageout daemon is 2078 * requesting a sync -- there might not be enough memory to do 2079 * the bmap then... So, this is important to do. 2080 */ 2081 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 2082 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 2083 } 2084 2085 /* 2086 * Set the *dirty* buffer range based upon the VM system dirty 2087 * pages. 2088 * 2089 * Mark the buffer pages as clean. We need to do this here to 2090 * satisfy the vnode_pager and the pageout daemon, so that it 2091 * thinks that the pages have been "cleaned". Note that since 2092 * the pages are in a delayed write buffer -- the VFS layer 2093 * "will" see that the pages get written out on the next sync, 2094 * or perhaps the cluster will be completed. 2095 */ 2096 vfs_clean_pages_dirty_buf(bp); 2097 bqrelse(bp); 2098 2099 /* 2100 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 2101 * due to the softdep code. 2102 */ 2103} 2104 2105/* 2106 * bdirty: 2107 * 2108 * Turn buffer into delayed write request. We must clear BIO_READ and 2109 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 2110 * itself to properly update it in the dirty/clean lists. We mark it 2111 * B_DONE to ensure that any asynchronization of the buffer properly 2112 * clears B_DONE ( else a panic will occur later ). 2113 * 2114 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 2115 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 2116 * should only be called if the buffer is known-good. 2117 * 2118 * Since the buffer is not on a queue, we do not update the numfreebuffers 2119 * count. 2120 * 2121 * The buffer must be on QUEUE_NONE. 2122 */ 2123void 2124bdirty(struct buf *bp) 2125{ 2126 2127 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 2128 bp, bp->b_vp, bp->b_flags); 2129 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2130 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 2131 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 2132 BUF_ASSERT_HELD(bp); 2133 bp->b_flags &= ~(B_RELBUF); 2134 bp->b_iocmd = BIO_WRITE; 2135 2136 if ((bp->b_flags & B_DELWRI) == 0) { 2137 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 2138 reassignbuf(bp); 2139 bdirtyadd(); 2140 } 2141} 2142 2143/* 2144 * bundirty: 2145 * 2146 * Clear B_DELWRI for buffer. 2147 * 2148 * Since the buffer is not on a queue, we do not update the numfreebuffers 2149 * count. 2150 * 2151 * The buffer must be on QUEUE_NONE. 2152 */ 2153 2154void 2155bundirty(struct buf *bp) 2156{ 2157 2158 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2159 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2160 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 2161 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 2162 BUF_ASSERT_HELD(bp); 2163 2164 if (bp->b_flags & B_DELWRI) { 2165 bp->b_flags &= ~B_DELWRI; 2166 reassignbuf(bp); 2167 bdirtysub(); 2168 } 2169 /* 2170 * Since it is now being written, we can clear its deferred write flag. 2171 */ 2172 bp->b_flags &= ~B_DEFERRED; 2173} 2174 2175/* 2176 * bawrite: 2177 * 2178 * Asynchronous write. Start output on a buffer, but do not wait for 2179 * it to complete. The buffer is released when the output completes. 2180 * 2181 * bwrite() ( or the VOP routine anyway ) is responsible for handling 2182 * B_INVAL buffers. Not us. 2183 */ 2184void 2185bawrite(struct buf *bp) 2186{ 2187 2188 bp->b_flags |= B_ASYNC; 2189 (void) bwrite(bp); 2190} 2191 2192/* 2193 * babarrierwrite: 2194 * 2195 * Asynchronous barrier write. Start output on a buffer, but do not 2196 * wait for it to complete. Place a write barrier after this write so 2197 * that this buffer and all buffers written before it are committed to 2198 * the disk before any buffers written after this write are committed 2199 * to the disk. The buffer is released when the output completes. 2200 */ 2201void 2202babarrierwrite(struct buf *bp) 2203{ 2204 2205 bp->b_flags |= B_ASYNC | B_BARRIER; 2206 (void) bwrite(bp); 2207} 2208 2209/* 2210 * bbarrierwrite: 2211 * 2212 * Synchronous barrier write. Start output on a buffer and wait for 2213 * it to complete. Place a write barrier after this write so that 2214 * this buffer and all buffers written before it are committed to 2215 * the disk before any buffers written after this write are committed 2216 * to the disk. The buffer is released when the output completes. 2217 */ 2218int 2219bbarrierwrite(struct buf *bp) 2220{ 2221 2222 bp->b_flags |= B_BARRIER; 2223 return (bwrite(bp)); 2224} 2225 2226/* 2227 * bwillwrite: 2228 * 2229 * Called prior to the locking of any vnodes when we are expecting to 2230 * write. We do not want to starve the buffer cache with too many 2231 * dirty buffers so we block here. By blocking prior to the locking 2232 * of any vnodes we attempt to avoid the situation where a locked vnode 2233 * prevents the various system daemons from flushing related buffers. 2234 */ 2235void 2236bwillwrite(void) 2237{ 2238 2239 if (numdirtybuffers >= hidirtybuffers) { 2240 mtx_lock(&bdirtylock); 2241 while (numdirtybuffers >= hidirtybuffers) { 2242 bdirtywait = 1; 2243 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4), 2244 "flswai", 0); 2245 } 2246 mtx_unlock(&bdirtylock); 2247 } 2248} 2249 2250/* 2251 * Return true if we have too many dirty buffers. 2252 */ 2253int 2254buf_dirty_count_severe(void) 2255{ 2256 2257 return(numdirtybuffers >= hidirtybuffers); 2258} 2259 2260/* 2261 * brelse: 2262 * 2263 * Release a busy buffer and, if requested, free its resources. The 2264 * buffer will be stashed in the appropriate bufqueue[] allowing it 2265 * to be accessed later as a cache entity or reused for other purposes. 2266 */ 2267void 2268brelse(struct buf *bp) 2269{ 2270 int qindex; 2271 2272 /* 2273 * Many functions erroneously call brelse with a NULL bp under rare 2274 * error conditions. Simply return when called with a NULL bp. 2275 */ 2276 if (bp == NULL) 2277 return; 2278 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 2279 bp, bp->b_vp, bp->b_flags); 2280 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 2281 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 2282 KASSERT((bp->b_flags & B_VMIO) != 0 || (bp->b_flags & B_NOREUSE) == 0, 2283 ("brelse: non-VMIO buffer marked NOREUSE")); 2284 2285 if (BUF_LOCKRECURSED(bp)) { 2286 /* 2287 * Do not process, in particular, do not handle the 2288 * B_INVAL/B_RELBUF and do not release to free list. 2289 */ 2290 BUF_UNLOCK(bp); 2291 return; 2292 } 2293 2294 if (bp->b_flags & B_MANAGED) { 2295 bqrelse(bp); 2296 return; 2297 } 2298 2299 if ((bp->b_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) { 2300 BO_LOCK(bp->b_bufobj); 2301 bp->b_vflags &= ~BV_BKGRDERR; 2302 BO_UNLOCK(bp->b_bufobj); 2303 bdirty(bp); 2304 } 2305 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 2306 !(bp->b_flags & B_INVAL)) { 2307 /* 2308 * Failed write, redirty. Must clear BIO_ERROR to prevent 2309 * pages from being scrapped. 2310 */ 2311 bp->b_ioflags &= ~BIO_ERROR; 2312 bdirty(bp); 2313 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 2314 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 2315 /* 2316 * Either a failed read I/O or we were asked to free or not 2317 * cache the buffer. 2318 */ 2319 bp->b_flags |= B_INVAL; 2320 if (!LIST_EMPTY(&bp->b_dep)) 2321 buf_deallocate(bp); 2322 if (bp->b_flags & B_DELWRI) 2323 bdirtysub(); 2324 bp->b_flags &= ~(B_DELWRI | B_CACHE); 2325 if ((bp->b_flags & B_VMIO) == 0) { 2326 allocbuf(bp, 0); 2327 if (bp->b_vp) 2328 brelvp(bp); 2329 } 2330 } 2331 2332 /* 2333 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_truncate() 2334 * is called with B_DELWRI set, the underlying pages may wind up 2335 * getting freed causing a previous write (bdwrite()) to get 'lost' 2336 * because pages associated with a B_DELWRI bp are marked clean. 2337 * 2338 * We still allow the B_INVAL case to call vfs_vmio_truncate(), even 2339 * if B_DELWRI is set. 2340 */ 2341 if (bp->b_flags & B_DELWRI) 2342 bp->b_flags &= ~B_RELBUF; 2343 2344 /* 2345 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 2346 * constituted, not even NFS buffers now. Two flags effect this. If 2347 * B_INVAL, the struct buf is invalidated but the VM object is kept 2348 * around ( i.e. so it is trivial to reconstitute the buffer later ). 2349 * 2350 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 2351 * invalidated. BIO_ERROR cannot be set for a failed write unless the 2352 * buffer is also B_INVAL because it hits the re-dirtying code above. 2353 * 2354 * Normally we can do this whether a buffer is B_DELWRI or not. If 2355 * the buffer is an NFS buffer, it is tracking piecemeal writes or 2356 * the commit state and we cannot afford to lose the buffer. If the 2357 * buffer has a background write in progress, we need to keep it 2358 * around to prevent it from being reconstituted and starting a second 2359 * background write. 2360 */ 2361 if ((bp->b_flags & B_VMIO) && (bp->b_flags & B_NOCACHE || 2362 (bp->b_ioflags & BIO_ERROR && bp->b_iocmd == BIO_READ)) && 2363 !(bp->b_vp->v_mount != NULL && 2364 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 2365 !vn_isdisk(bp->b_vp, NULL) && (bp->b_flags & B_DELWRI))) { 2366 vfs_vmio_invalidate(bp); 2367 allocbuf(bp, 0); 2368 } 2369 2370 if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0 || 2371 (bp->b_flags & (B_DELWRI | B_NOREUSE)) == B_NOREUSE) { 2372 allocbuf(bp, 0); 2373 bp->b_flags &= ~B_NOREUSE; 2374 if (bp->b_vp != NULL) 2375 brelvp(bp); 2376 } 2377 2378 /* 2379 * If the buffer has junk contents signal it and eventually 2380 * clean up B_DELWRI and diassociate the vnode so that gbincore() 2381 * doesn't find it. 2382 */ 2383 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 2384 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 2385 bp->b_flags |= B_INVAL; 2386 if (bp->b_flags & B_INVAL) { 2387 if (bp->b_flags & B_DELWRI) 2388 bundirty(bp); 2389 if (bp->b_vp) 2390 brelvp(bp); 2391 } 2392 2393 /* buffers with no memory */ 2394 if (bp->b_bufsize == 0) { 2395 buf_free(bp); 2396 return; 2397 } 2398 /* buffers with junk contents */ 2399 if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 2400 (bp->b_ioflags & BIO_ERROR)) { 2401 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 2402 if (bp->b_vflags & BV_BKGRDINPROG) 2403 panic("losing buffer 2"); 2404 qindex = QUEUE_CLEAN; 2405 bp->b_flags |= B_AGE; 2406 /* remaining buffers */ 2407 } else if (bp->b_flags & B_DELWRI) 2408 qindex = QUEUE_DIRTY; 2409 else 2410 qindex = QUEUE_CLEAN; 2411 2412 binsfree(bp, qindex); 2413 2414 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 2415 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 2416 panic("brelse: not dirty"); 2417 /* unlock */ 2418 BUF_UNLOCK(bp); 2419 if (qindex == QUEUE_CLEAN) 2420 bufspace_wakeup(); 2421} 2422 2423/* 2424 * Release a buffer back to the appropriate queue but do not try to free 2425 * it. The buffer is expected to be used again soon. 2426 * 2427 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 2428 * biodone() to requeue an async I/O on completion. It is also used when 2429 * known good buffers need to be requeued but we think we may need the data 2430 * again soon. 2431 * 2432 * XXX we should be able to leave the B_RELBUF hint set on completion. 2433 */ 2434void 2435bqrelse(struct buf *bp) 2436{ 2437 int qindex; 2438 2439 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2440 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 2441 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 2442 2443 qindex = QUEUE_NONE; 2444 if (BUF_LOCKRECURSED(bp)) { 2445 /* do not release to free list */ 2446 BUF_UNLOCK(bp); 2447 return; 2448 } 2449 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 2450 2451 if (bp->b_flags & B_MANAGED) { 2452 if (bp->b_flags & B_REMFREE) 2453 bremfreef(bp); 2454 goto out; 2455 } 2456 2457 /* buffers with stale but valid contents */ 2458 if ((bp->b_flags & B_DELWRI) != 0 || (bp->b_vflags & (BV_BKGRDINPROG | 2459 BV_BKGRDERR)) == BV_BKGRDERR) { 2460 BO_LOCK(bp->b_bufobj); 2461 bp->b_vflags &= ~BV_BKGRDERR; 2462 BO_UNLOCK(bp->b_bufobj); 2463 qindex = QUEUE_DIRTY; 2464 } else { 2465 if ((bp->b_flags & B_DELWRI) == 0 && 2466 (bp->b_xflags & BX_VNDIRTY)) 2467 panic("bqrelse: not dirty"); 2468 if ((bp->b_flags & B_NOREUSE) != 0) { 2469 brelse(bp); 2470 return; 2471 } 2472 qindex = QUEUE_CLEAN; 2473 } 2474 binsfree(bp, qindex); 2475 2476out: 2477 /* unlock */ 2478 BUF_UNLOCK(bp); 2479 if (qindex == QUEUE_CLEAN) 2480 bufspace_wakeup(); 2481} 2482 2483/* 2484 * Complete I/O to a VMIO backed page. Validate the pages as appropriate, 2485 * restore bogus pages. 2486 */ 2487static void 2488vfs_vmio_iodone(struct buf *bp) 2489{ 2490 vm_ooffset_t foff; 2491 vm_page_t m; 2492 vm_object_t obj; 2493 struct vnode *vp; 2494 int bogus, i, iosize; 2495 2496 obj = bp->b_bufobj->bo_object; 2497 KASSERT(obj->paging_in_progress >= bp->b_npages, 2498 ("vfs_vmio_iodone: paging in progress(%d) < b_npages(%d)", 2499 obj->paging_in_progress, bp->b_npages)); 2500 2501 vp = bp->b_vp; 2502 KASSERT(vp->v_holdcnt > 0, 2503 ("vfs_vmio_iodone: vnode %p has zero hold count", vp)); 2504 KASSERT(vp->v_object != NULL, 2505 ("vfs_vmio_iodone: vnode %p has no vm_object", vp)); 2506 2507 foff = bp->b_offset; 2508 KASSERT(bp->b_offset != NOOFFSET, 2509 ("vfs_vmio_iodone: bp %p has no buffer offset", bp)); 2510 2511 bogus = 0; 2512 iosize = bp->b_bcount - bp->b_resid; 2513 VM_OBJECT_WLOCK(obj); 2514 for (i = 0; i < bp->b_npages; i++) { 2515 int resid; 2516 2517 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 2518 if (resid > iosize) 2519 resid = iosize; 2520 2521 /* 2522 * cleanup bogus pages, restoring the originals 2523 */ 2524 m = bp->b_pages[i]; 2525 if (m == bogus_page) { 2526 bogus = 1; 2527 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 2528 if (m == NULL) 2529 panic("biodone: page disappeared!"); 2530 bp->b_pages[i] = m; 2531 } else if ((bp->b_iocmd == BIO_READ) && resid > 0) { 2532 /* 2533 * In the write case, the valid and clean bits are 2534 * already changed correctly ( see bdwrite() ), so we 2535 * only need to do this here in the read case. 2536 */ 2537 KASSERT((m->dirty & vm_page_bits(foff & PAGE_MASK, 2538 resid)) == 0, ("vfs_vmio_iodone: page %p " 2539 "has unexpected dirty bits", m)); 2540 vfs_page_set_valid(bp, foff, m); 2541 } 2542 KASSERT(OFF_TO_IDX(foff) == m->pindex, 2543 ("vfs_vmio_iodone: foff(%jd)/pindex(%ju) mismatch", 2544 (intmax_t)foff, (uintmax_t)m->pindex)); 2545 2546 vm_page_sunbusy(m); 2547 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2548 iosize -= resid; 2549 } 2550 vm_object_pip_wakeupn(obj, bp->b_npages); 2551 VM_OBJECT_WUNLOCK(obj); 2552 if (bogus && buf_mapped(bp)) { 2553 BUF_CHECK_MAPPED(bp); 2554 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 2555 bp->b_pages, bp->b_npages); 2556 } 2557} 2558 2559/* 2560 * Unwire a page held by a buf and place it on the appropriate vm queue. 2561 */ 2562static void 2563vfs_vmio_unwire(struct buf *bp, vm_page_t m) 2564{ 2565 bool freed; 2566 2567 vm_page_lock(m); 2568 if (vm_page_unwire(m, PQ_NONE)) { 2569 /* 2570 * Determine if the page should be freed before adding 2571 * it to the inactive queue. 2572 */ 2573 if (m->valid == 0) { 2574 freed = !vm_page_busied(m); 2575 if (freed) 2576 vm_page_free(m); 2577 } else if ((bp->b_flags & B_DIRECT) != 0) 2578 freed = vm_page_try_to_free(m); 2579 else 2580 freed = false; 2581 if (!freed) { 2582 /* 2583 * If the page is unlikely to be reused, let the 2584 * VM know. Otherwise, maintain LRU page 2585 * ordering and put the page at the tail of the 2586 * inactive queue. 2587 */ 2588 if ((bp->b_flags & B_NOREUSE) != 0) 2589 vm_page_deactivate_noreuse(m); 2590 else 2591 vm_page_deactivate(m); 2592 } 2593 } 2594 vm_page_unlock(m); 2595} 2596 2597/* 2598 * Perform page invalidation when a buffer is released. The fully invalid 2599 * pages will be reclaimed later in vfs_vmio_truncate(). 2600 */ 2601static void 2602vfs_vmio_invalidate(struct buf *bp) 2603{ 2604 vm_object_t obj; 2605 vm_page_t m; 2606 int i, resid, poffset, presid; 2607 2608 if (buf_mapped(bp)) { 2609 BUF_CHECK_MAPPED(bp); 2610 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages); 2611 } else 2612 BUF_CHECK_UNMAPPED(bp); 2613 /* 2614 * Get the base offset and length of the buffer. Note that 2615 * in the VMIO case if the buffer block size is not 2616 * page-aligned then b_data pointer may not be page-aligned. 2617 * But our b_pages[] array *IS* page aligned. 2618 * 2619 * block sizes less then DEV_BSIZE (usually 512) are not 2620 * supported due to the page granularity bits (m->valid, 2621 * m->dirty, etc...). 2622 * 2623 * See man buf(9) for more information 2624 */ 2625 obj = bp->b_bufobj->bo_object; 2626 resid = bp->b_bufsize; 2627 poffset = bp->b_offset & PAGE_MASK; 2628 VM_OBJECT_WLOCK(obj); 2629 for (i = 0; i < bp->b_npages; i++) { 2630 m = bp->b_pages[i]; 2631 if (m == bogus_page) 2632 panic("vfs_vmio_invalidate: Unexpected bogus page."); 2633 bp->b_pages[i] = NULL; 2634 2635 presid = resid > (PAGE_SIZE - poffset) ? 2636 (PAGE_SIZE - poffset) : resid; 2637 KASSERT(presid >= 0, ("brelse: extra page")); 2638 while (vm_page_xbusied(m)) { 2639 vm_page_lock(m); 2640 VM_OBJECT_WUNLOCK(obj); 2641 vm_page_busy_sleep(m, "mbncsh", true); 2642 VM_OBJECT_WLOCK(obj); 2643 } 2644 if (pmap_page_wired_mappings(m) == 0) 2645 vm_page_set_invalid(m, poffset, presid); 2646 vfs_vmio_unwire(bp, m); 2647 resid -= presid; 2648 poffset = 0; 2649 } 2650 VM_OBJECT_WUNLOCK(obj); 2651 bp->b_npages = 0; 2652} 2653 2654/* 2655 * Page-granular truncation of an existing VMIO buffer. 2656 */ 2657static void 2658vfs_vmio_truncate(struct buf *bp, int desiredpages) 2659{ 2660 vm_object_t obj; 2661 vm_page_t m; 2662 int i; 2663 2664 if (bp->b_npages == desiredpages) 2665 return; 2666 2667 if (buf_mapped(bp)) { 2668 BUF_CHECK_MAPPED(bp); 2669 pmap_qremove((vm_offset_t)trunc_page((vm_offset_t)bp->b_data) + 2670 (desiredpages << PAGE_SHIFT), bp->b_npages - desiredpages); 2671 } else 2672 BUF_CHECK_UNMAPPED(bp); 2673 obj = bp->b_bufobj->bo_object; 2674 if (obj != NULL) 2675 VM_OBJECT_WLOCK(obj); 2676 for (i = desiredpages; i < bp->b_npages; i++) { 2677 m = bp->b_pages[i]; 2678 KASSERT(m != bogus_page, ("allocbuf: bogus page found")); 2679 bp->b_pages[i] = NULL; 2680 vfs_vmio_unwire(bp, m); 2681 } 2682 if (obj != NULL) 2683 VM_OBJECT_WUNLOCK(obj); 2684 bp->b_npages = desiredpages; 2685} 2686 2687/* 2688 * Byte granular extension of VMIO buffers. 2689 */ 2690static void 2691vfs_vmio_extend(struct buf *bp, int desiredpages, int size) 2692{ 2693 /* 2694 * We are growing the buffer, possibly in a 2695 * byte-granular fashion. 2696 */ 2697 vm_object_t obj; 2698 vm_offset_t toff; 2699 vm_offset_t tinc; 2700 vm_page_t m; 2701 2702 /* 2703 * Step 1, bring in the VM pages from the object, allocating 2704 * them if necessary. We must clear B_CACHE if these pages 2705 * are not valid for the range covered by the buffer. 2706 */ 2707 obj = bp->b_bufobj->bo_object; 2708 VM_OBJECT_WLOCK(obj); 2709 while (bp->b_npages < desiredpages) { 2710 /* 2711 * We must allocate system pages since blocking 2712 * here could interfere with paging I/O, no 2713 * matter which process we are. 2714 * 2715 * Only exclusive busy can be tested here. 2716 * Blocking on shared busy might lead to 2717 * deadlocks once allocbuf() is called after 2718 * pages are vfs_busy_pages(). 2719 */ 2720 m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) + bp->b_npages, 2721 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM | 2722 VM_ALLOC_WIRED | VM_ALLOC_IGN_SBUSY | 2723 VM_ALLOC_COUNT(desiredpages - bp->b_npages)); 2724 if (m->valid == 0) 2725 bp->b_flags &= ~B_CACHE; 2726 bp->b_pages[bp->b_npages] = m; 2727 ++bp->b_npages; 2728 } 2729 2730 /* 2731 * Step 2. We've loaded the pages into the buffer, 2732 * we have to figure out if we can still have B_CACHE 2733 * set. Note that B_CACHE is set according to the 2734 * byte-granular range ( bcount and size ), not the 2735 * aligned range ( newbsize ). 2736 * 2737 * The VM test is against m->valid, which is DEV_BSIZE 2738 * aligned. Needless to say, the validity of the data 2739 * needs to also be DEV_BSIZE aligned. Note that this 2740 * fails with NFS if the server or some other client 2741 * extends the file's EOF. If our buffer is resized, 2742 * B_CACHE may remain set! XXX 2743 */ 2744 toff = bp->b_bcount; 2745 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 2746 while ((bp->b_flags & B_CACHE) && toff < size) { 2747 vm_pindex_t pi; 2748 2749 if (tinc > (size - toff)) 2750 tinc = size - toff; 2751 pi = ((bp->b_offset & PAGE_MASK) + toff) >> PAGE_SHIFT; 2752 m = bp->b_pages[pi]; 2753 vfs_buf_test_cache(bp, bp->b_offset, toff, tinc, m); 2754 toff += tinc; 2755 tinc = PAGE_SIZE; 2756 } 2757 VM_OBJECT_WUNLOCK(obj); 2758 2759 /* 2760 * Step 3, fixup the KVA pmap. 2761 */ 2762 if (buf_mapped(bp)) 2763 bpmap_qenter(bp); 2764 else 2765 BUF_CHECK_UNMAPPED(bp); 2766} 2767 2768/* 2769 * Check to see if a block at a particular lbn is available for a clustered 2770 * write. 2771 */ 2772static int 2773vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 2774{ 2775 struct buf *bpa; 2776 int match; 2777 2778 match = 0; 2779 2780 /* If the buf isn't in core skip it */ 2781 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 2782 return (0); 2783 2784 /* If the buf is busy we don't want to wait for it */ 2785 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2786 return (0); 2787 2788 /* Only cluster with valid clusterable delayed write buffers */ 2789 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 2790 (B_DELWRI | B_CLUSTEROK)) 2791 goto done; 2792 2793 if (bpa->b_bufsize != size) 2794 goto done; 2795 2796 /* 2797 * Check to see if it is in the expected place on disk and that the 2798 * block has been mapped. 2799 */ 2800 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 2801 match = 1; 2802done: 2803 BUF_UNLOCK(bpa); 2804 return (match); 2805} 2806 2807/* 2808 * vfs_bio_awrite: 2809 * 2810 * Implement clustered async writes for clearing out B_DELWRI buffers. 2811 * This is much better then the old way of writing only one buffer at 2812 * a time. Note that we may not be presented with the buffers in the 2813 * correct order, so we search for the cluster in both directions. 2814 */ 2815int 2816vfs_bio_awrite(struct buf *bp) 2817{ 2818 struct bufobj *bo; 2819 int i; 2820 int j; 2821 daddr_t lblkno = bp->b_lblkno; 2822 struct vnode *vp = bp->b_vp; 2823 int ncl; 2824 int nwritten; 2825 int size; 2826 int maxcl; 2827 int gbflags; 2828 2829 bo = &vp->v_bufobj; 2830 gbflags = (bp->b_data == unmapped_buf) ? GB_UNMAPPED : 0; 2831 /* 2832 * right now we support clustered writing only to regular files. If 2833 * we find a clusterable block we could be in the middle of a cluster 2834 * rather then at the beginning. 2835 */ 2836 if ((vp->v_type == VREG) && 2837 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 2838 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 2839 2840 size = vp->v_mount->mnt_stat.f_iosize; 2841 maxcl = MAXPHYS / size; 2842 2843 BO_RLOCK(bo); 2844 for (i = 1; i < maxcl; i++) 2845 if (vfs_bio_clcheck(vp, size, lblkno + i, 2846 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 2847 break; 2848 2849 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 2850 if (vfs_bio_clcheck(vp, size, lblkno - j, 2851 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 2852 break; 2853 BO_RUNLOCK(bo); 2854 --j; 2855 ncl = i + j; 2856 /* 2857 * this is a possible cluster write 2858 */ 2859 if (ncl != 1) { 2860 BUF_UNLOCK(bp); 2861 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl, 2862 gbflags); 2863 return (nwritten); 2864 } 2865 } 2866 bremfree(bp); 2867 bp->b_flags |= B_ASYNC; 2868 /* 2869 * default (old) behavior, writing out only one block 2870 * 2871 * XXX returns b_bufsize instead of b_bcount for nwritten? 2872 */ 2873 nwritten = bp->b_bufsize; 2874 (void) bwrite(bp); 2875 2876 return (nwritten); 2877} 2878 2879/* 2880 * getnewbuf_kva: 2881 * 2882 * Allocate KVA for an empty buf header according to gbflags. 2883 */ 2884static int 2885getnewbuf_kva(struct buf *bp, int gbflags, int maxsize) 2886{ 2887 2888 if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_UNMAPPED) { 2889 /* 2890 * In order to keep fragmentation sane we only allocate kva 2891 * in BKVASIZE chunks. XXX with vmem we can do page size. 2892 */ 2893 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2894 2895 if (maxsize != bp->b_kvasize && 2896 bufkva_alloc(bp, maxsize, gbflags)) 2897 return (ENOSPC); 2898 } 2899 return (0); 2900} 2901 2902/* 2903 * getnewbuf: 2904 * 2905 * Find and initialize a new buffer header, freeing up existing buffers 2906 * in the bufqueues as necessary. The new buffer is returned locked. 2907 * 2908 * We block if: 2909 * We have insufficient buffer headers 2910 * We have insufficient buffer space 2911 * buffer_arena is too fragmented ( space reservation fails ) 2912 * If we have to flush dirty buffers ( but we try to avoid this ) 2913 * 2914 * The caller is responsible for releasing the reserved bufspace after 2915 * allocbuf() is called. 2916 */ 2917static struct buf * 2918getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int maxsize, int gbflags) 2919{ 2920 struct buf *bp; 2921 bool metadata, reserved; 2922 2923 bp = NULL; 2924 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 2925 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 2926 if (!unmapped_buf_allowed) 2927 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC); 2928 2929 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 || 2930 vp->v_type == VCHR) 2931 metadata = true; 2932 else 2933 metadata = false; 2934 atomic_add_int(&getnewbufcalls, 1); 2935 reserved = false; 2936 do { 2937 if (reserved == false && 2938 bufspace_reserve(maxsize, metadata) != 0) 2939 continue; 2940 reserved = true; 2941 if ((bp = buf_alloc()) == NULL) 2942 continue; 2943 if (getnewbuf_kva(bp, gbflags, maxsize) == 0) 2944 return (bp); 2945 break; 2946 } while(buf_scan(false) == 0); 2947 2948 if (reserved) 2949 atomic_subtract_long(&bufspace, maxsize); 2950 if (bp != NULL) { 2951 bp->b_flags |= B_INVAL; 2952 brelse(bp); 2953 } 2954 bufspace_wait(vp, gbflags, slpflag, slptimeo); 2955 2956 return (NULL); 2957} 2958 2959/* 2960 * buf_daemon: 2961 * 2962 * buffer flushing daemon. Buffers are normally flushed by the 2963 * update daemon but if it cannot keep up this process starts to 2964 * take the load in an attempt to prevent getnewbuf() from blocking. 2965 */ 2966static struct kproc_desc buf_kp = { 2967 "bufdaemon", 2968 buf_daemon, 2969 &bufdaemonproc 2970}; 2971SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 2972 2973static int 2974buf_flush(struct vnode *vp, int target) 2975{ 2976 int flushed; 2977 2978 flushed = flushbufqueues(vp, target, 0); 2979 if (flushed == 0) { 2980 /* 2981 * Could not find any buffers without rollback 2982 * dependencies, so just write the first one 2983 * in the hopes of eventually making progress. 2984 */ 2985 if (vp != NULL && target > 2) 2986 target /= 2; 2987 flushbufqueues(vp, target, 1); 2988 } 2989 return (flushed); 2990} 2991 2992static void 2993buf_daemon() 2994{ 2995 int lodirty; 2996 2997 /* 2998 * This process needs to be suspended prior to shutdown sync. 2999 */ 3000 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 3001 SHUTDOWN_PRI_LAST); 3002 3003 /* 3004 * This process is allowed to take the buffer cache to the limit 3005 */ 3006 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 3007 mtx_lock(&bdlock); 3008 for (;;) { 3009 bd_request = 0; 3010 mtx_unlock(&bdlock); 3011 3012 kproc_suspend_check(bufdaemonproc); 3013 lodirty = lodirtybuffers; 3014 if (bd_speedupreq) { 3015 lodirty = numdirtybuffers / 2; 3016 bd_speedupreq = 0; 3017 } 3018 /* 3019 * Do the flush. Limit the amount of in-transit I/O we 3020 * allow to build up, otherwise we would completely saturate 3021 * the I/O system. 3022 */ 3023 while (numdirtybuffers > lodirty) { 3024 if (buf_flush(NULL, numdirtybuffers - lodirty) == 0) 3025 break; 3026 kern_yield(PRI_USER); 3027 } 3028 3029 /* 3030 * Only clear bd_request if we have reached our low water 3031 * mark. The buf_daemon normally waits 1 second and 3032 * then incrementally flushes any dirty buffers that have 3033 * built up, within reason. 3034 * 3035 * If we were unable to hit our low water mark and couldn't 3036 * find any flushable buffers, we sleep for a short period 3037 * to avoid endless loops on unlockable buffers. 3038 */ 3039 mtx_lock(&bdlock); 3040 if (numdirtybuffers <= lodirtybuffers) { 3041 /* 3042 * We reached our low water mark, reset the 3043 * request and sleep until we are needed again. 3044 * The sleep is just so the suspend code works. 3045 */ 3046 bd_request = 0; 3047 /* 3048 * Do an extra wakeup in case dirty threshold 3049 * changed via sysctl and the explicit transition 3050 * out of shortfall was missed. 3051 */ 3052 bdirtywakeup(); 3053 if (runningbufspace <= lorunningspace) 3054 runningwakeup(); 3055 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 3056 } else { 3057 /* 3058 * We couldn't find any flushable dirty buffers but 3059 * still have too many dirty buffers, we 3060 * have to sleep and try again. (rare) 3061 */ 3062 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 3063 } 3064 } 3065} 3066 3067/* 3068 * flushbufqueues: 3069 * 3070 * Try to flush a buffer in the dirty queue. We must be careful to 3071 * free up B_INVAL buffers instead of write them, which NFS is 3072 * particularly sensitive to. 3073 */ 3074static int flushwithdeps = 0; 3075SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 3076 0, "Number of buffers flushed with dependecies that require rollbacks"); 3077 3078static int 3079flushbufqueues(struct vnode *lvp, int target, int flushdeps) 3080{ 3081 struct buf *sentinel; 3082 struct vnode *vp; 3083 struct mount *mp; 3084 struct buf *bp; 3085 int hasdeps; 3086 int flushed; 3087 int queue; 3088 int error; 3089 bool unlock; 3090 3091 flushed = 0; 3092 queue = QUEUE_DIRTY; 3093 bp = NULL; 3094 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 3095 sentinel->b_qindex = QUEUE_SENTINEL; 3096 mtx_lock(&bqlocks[queue]); 3097 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist); 3098 mtx_unlock(&bqlocks[queue]); 3099 while (flushed != target) { 3100 maybe_yield(); 3101 mtx_lock(&bqlocks[queue]); 3102 bp = TAILQ_NEXT(sentinel, b_freelist); 3103 if (bp != NULL) { 3104 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 3105 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel, 3106 b_freelist); 3107 } else { 3108 mtx_unlock(&bqlocks[queue]); 3109 break; 3110 } 3111 /* 3112 * Skip sentinels inserted by other invocations of the 3113 * flushbufqueues(), taking care to not reorder them. 3114 * 3115 * Only flush the buffers that belong to the 3116 * vnode locked by the curthread. 3117 */ 3118 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL && 3119 bp->b_vp != lvp)) { 3120 mtx_unlock(&bqlocks[queue]); 3121 continue; 3122 } 3123 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL); 3124 mtx_unlock(&bqlocks[queue]); 3125 if (error != 0) 3126 continue; 3127 if (bp->b_pin_count > 0) { 3128 BUF_UNLOCK(bp); 3129 continue; 3130 } 3131 /* 3132 * BKGRDINPROG can only be set with the buf and bufobj 3133 * locks both held. We tolerate a race to clear it here. 3134 */ 3135 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 3136 (bp->b_flags & B_DELWRI) == 0) { 3137 BUF_UNLOCK(bp); 3138 continue; 3139 } 3140 if (bp->b_flags & B_INVAL) { 3141 bremfreef(bp); 3142 brelse(bp); 3143 flushed++; 3144 continue; 3145 } 3146 3147 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 3148 if (flushdeps == 0) { 3149 BUF_UNLOCK(bp); 3150 continue; 3151 } 3152 hasdeps = 1; 3153 } else 3154 hasdeps = 0; 3155 /* 3156 * We must hold the lock on a vnode before writing 3157 * one of its buffers. Otherwise we may confuse, or 3158 * in the case of a snapshot vnode, deadlock the 3159 * system. 3160 * 3161 * The lock order here is the reverse of the normal 3162 * of vnode followed by buf lock. This is ok because 3163 * the NOWAIT will prevent deadlock. 3164 */ 3165 vp = bp->b_vp; 3166 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 3167 BUF_UNLOCK(bp); 3168 continue; 3169 } 3170 if (lvp == NULL) { 3171 unlock = true; 3172 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT); 3173 } else { 3174 ASSERT_VOP_LOCKED(vp, "getbuf"); 3175 unlock = false; 3176 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 : 3177 vn_lock(vp, LK_TRYUPGRADE); 3178 } 3179 if (error == 0) { 3180 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 3181 bp, bp->b_vp, bp->b_flags); 3182 if (curproc == bufdaemonproc) { 3183 vfs_bio_awrite(bp); 3184 } else { 3185 bremfree(bp); 3186 bwrite(bp); 3187 notbufdflushes++; 3188 } 3189 vn_finished_write(mp); 3190 if (unlock) 3191 VOP_UNLOCK(vp, 0); 3192 flushwithdeps += hasdeps; 3193 flushed++; 3194 3195 /* 3196 * Sleeping on runningbufspace while holding 3197 * vnode lock leads to deadlock. 3198 */ 3199 if (curproc == bufdaemonproc && 3200 runningbufspace > hirunningspace) 3201 waitrunningbufspace(); 3202 continue; 3203 } 3204 vn_finished_write(mp); 3205 BUF_UNLOCK(bp); 3206 } 3207 mtx_lock(&bqlocks[queue]); 3208 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 3209 mtx_unlock(&bqlocks[queue]); 3210 free(sentinel, M_TEMP); 3211 return (flushed); 3212} 3213 3214/* 3215 * Check to see if a block is currently memory resident. 3216 */ 3217struct buf * 3218incore(struct bufobj *bo, daddr_t blkno) 3219{ 3220 struct buf *bp; 3221 3222 BO_RLOCK(bo); 3223 bp = gbincore(bo, blkno); 3224 BO_RUNLOCK(bo); 3225 return (bp); 3226} 3227 3228/* 3229 * Returns true if no I/O is needed to access the 3230 * associated VM object. This is like incore except 3231 * it also hunts around in the VM system for the data. 3232 */ 3233 3234static int 3235inmem(struct vnode * vp, daddr_t blkno) 3236{ 3237 vm_object_t obj; 3238 vm_offset_t toff, tinc, size; 3239 vm_page_t m; 3240 vm_ooffset_t off; 3241 3242 ASSERT_VOP_LOCKED(vp, "inmem"); 3243 3244 if (incore(&vp->v_bufobj, blkno)) 3245 return 1; 3246 if (vp->v_mount == NULL) 3247 return 0; 3248 obj = vp->v_object; 3249 if (obj == NULL) 3250 return (0); 3251 3252 size = PAGE_SIZE; 3253 if (size > vp->v_mount->mnt_stat.f_iosize) 3254 size = vp->v_mount->mnt_stat.f_iosize; 3255 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 3256 3257 VM_OBJECT_RLOCK(obj); 3258 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 3259 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 3260 if (!m) 3261 goto notinmem; 3262 tinc = size; 3263 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 3264 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 3265 if (vm_page_is_valid(m, 3266 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 3267 goto notinmem; 3268 } 3269 VM_OBJECT_RUNLOCK(obj); 3270 return 1; 3271 3272notinmem: 3273 VM_OBJECT_RUNLOCK(obj); 3274 return (0); 3275} 3276 3277/* 3278 * Set the dirty range for a buffer based on the status of the dirty 3279 * bits in the pages comprising the buffer. The range is limited 3280 * to the size of the buffer. 3281 * 3282 * Tell the VM system that the pages associated with this buffer 3283 * are clean. This is used for delayed writes where the data is 3284 * going to go to disk eventually without additional VM intevention. 3285 * 3286 * Note that while we only really need to clean through to b_bcount, we 3287 * just go ahead and clean through to b_bufsize. 3288 */ 3289static void 3290vfs_clean_pages_dirty_buf(struct buf *bp) 3291{ 3292 vm_ooffset_t foff, noff, eoff; 3293 vm_page_t m; 3294 int i; 3295 3296 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 3297 return; 3298 3299 foff = bp->b_offset; 3300 KASSERT(bp->b_offset != NOOFFSET, 3301 ("vfs_clean_pages_dirty_buf: no buffer offset")); 3302 3303 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 3304 vfs_drain_busy_pages(bp); 3305 vfs_setdirty_locked_object(bp); 3306 for (i = 0; i < bp->b_npages; i++) { 3307 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3308 eoff = noff; 3309 if (eoff > bp->b_offset + bp->b_bufsize) 3310 eoff = bp->b_offset + bp->b_bufsize; 3311 m = bp->b_pages[i]; 3312 vfs_page_set_validclean(bp, foff, m); 3313 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3314 foff = noff; 3315 } 3316 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 3317} 3318 3319static void 3320vfs_setdirty_locked_object(struct buf *bp) 3321{ 3322 vm_object_t object; 3323 int i; 3324 3325 object = bp->b_bufobj->bo_object; 3326 VM_OBJECT_ASSERT_WLOCKED(object); 3327 3328 /* 3329 * We qualify the scan for modified pages on whether the 3330 * object has been flushed yet. 3331 */ 3332 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) { 3333 vm_offset_t boffset; 3334 vm_offset_t eoffset; 3335 3336 /* 3337 * test the pages to see if they have been modified directly 3338 * by users through the VM system. 3339 */ 3340 for (i = 0; i < bp->b_npages; i++) 3341 vm_page_test_dirty(bp->b_pages[i]); 3342 3343 /* 3344 * Calculate the encompassing dirty range, boffset and eoffset, 3345 * (eoffset - boffset) bytes. 3346 */ 3347 3348 for (i = 0; i < bp->b_npages; i++) { 3349 if (bp->b_pages[i]->dirty) 3350 break; 3351 } 3352 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3353 3354 for (i = bp->b_npages - 1; i >= 0; --i) { 3355 if (bp->b_pages[i]->dirty) { 3356 break; 3357 } 3358 } 3359 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3360 3361 /* 3362 * Fit it to the buffer. 3363 */ 3364 3365 if (eoffset > bp->b_bcount) 3366 eoffset = bp->b_bcount; 3367 3368 /* 3369 * If we have a good dirty range, merge with the existing 3370 * dirty range. 3371 */ 3372 3373 if (boffset < eoffset) { 3374 if (bp->b_dirtyoff > boffset) 3375 bp->b_dirtyoff = boffset; 3376 if (bp->b_dirtyend < eoffset) 3377 bp->b_dirtyend = eoffset; 3378 } 3379 } 3380} 3381 3382/* 3383 * Allocate the KVA mapping for an existing buffer. 3384 * If an unmapped buffer is provided but a mapped buffer is requested, take 3385 * also care to properly setup mappings between pages and KVA. 3386 */ 3387static void 3388bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags) 3389{ 3390 int bsize, maxsize, need_mapping, need_kva; 3391 off_t offset; 3392 3393 need_mapping = bp->b_data == unmapped_buf && 3394 (gbflags & GB_UNMAPPED) == 0; 3395 need_kva = bp->b_kvabase == unmapped_buf && 3396 bp->b_data == unmapped_buf && 3397 (gbflags & GB_KVAALLOC) != 0; 3398 if (!need_mapping && !need_kva) 3399 return; 3400 3401 BUF_CHECK_UNMAPPED(bp); 3402 3403 if (need_mapping && bp->b_kvabase != unmapped_buf) { 3404 /* 3405 * Buffer is not mapped, but the KVA was already 3406 * reserved at the time of the instantiation. Use the 3407 * allocated space. 3408 */ 3409 goto has_addr; 3410 } 3411 3412 /* 3413 * Calculate the amount of the address space we would reserve 3414 * if the buffer was mapped. 3415 */ 3416 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize; 3417 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3418 offset = blkno * bsize; 3419 maxsize = size + (offset & PAGE_MASK); 3420 maxsize = imax(maxsize, bsize); 3421 3422 while (bufkva_alloc(bp, maxsize, gbflags) != 0) { 3423 if ((gbflags & GB_NOWAIT_BD) != 0) { 3424 /* 3425 * XXXKIB: defragmentation cannot 3426 * succeed, not sure what else to do. 3427 */ 3428 panic("GB_NOWAIT_BD and GB_UNMAPPED %p", bp); 3429 } 3430 atomic_add_int(&mappingrestarts, 1); 3431 bufspace_wait(bp->b_vp, gbflags, 0, 0); 3432 } 3433has_addr: 3434 if (need_mapping) { 3435 /* b_offset is handled by bpmap_qenter. */ 3436 bp->b_data = bp->b_kvabase; 3437 BUF_CHECK_MAPPED(bp); 3438 bpmap_qenter(bp); 3439 } 3440} 3441 3442/* 3443 * getblk: 3444 * 3445 * Get a block given a specified block and offset into a file/device. 3446 * The buffers B_DONE bit will be cleared on return, making it almost 3447 * ready for an I/O initiation. B_INVAL may or may not be set on 3448 * return. The caller should clear B_INVAL prior to initiating a 3449 * READ. 3450 * 3451 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 3452 * an existing buffer. 3453 * 3454 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 3455 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 3456 * and then cleared based on the backing VM. If the previous buffer is 3457 * non-0-sized but invalid, B_CACHE will be cleared. 3458 * 3459 * If getblk() must create a new buffer, the new buffer is returned with 3460 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 3461 * case it is returned with B_INVAL clear and B_CACHE set based on the 3462 * backing VM. 3463 * 3464 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 3465 * B_CACHE bit is clear. 3466 * 3467 * What this means, basically, is that the caller should use B_CACHE to 3468 * determine whether the buffer is fully valid or not and should clear 3469 * B_INVAL prior to issuing a read. If the caller intends to validate 3470 * the buffer by loading its data area with something, the caller needs 3471 * to clear B_INVAL. If the caller does this without issuing an I/O, 3472 * the caller should set B_CACHE ( as an optimization ), else the caller 3473 * should issue the I/O and biodone() will set B_CACHE if the I/O was 3474 * a write attempt or if it was a successful read. If the caller 3475 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 3476 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 3477 */ 3478struct buf * 3479getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3480 int flags) 3481{ 3482 struct buf *bp; 3483 struct bufobj *bo; 3484 int bsize, error, maxsize, vmio; 3485 off_t offset; 3486 3487 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 3488 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3489 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3490 ASSERT_VOP_LOCKED(vp, "getblk"); 3491 if (size > MAXBCACHEBUF) 3492 panic("getblk: size(%d) > MAXBCACHEBUF(%d)\n", size, 3493 MAXBCACHEBUF); 3494 if (!unmapped_buf_allowed) 3495 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3496 3497 bo = &vp->v_bufobj; 3498loop: 3499 BO_RLOCK(bo); 3500 bp = gbincore(bo, blkno); 3501 if (bp != NULL) { 3502 int lockflags; 3503 /* 3504 * Buffer is in-core. If the buffer is not busy nor managed, 3505 * it must be on a queue. 3506 */ 3507 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 3508 3509 if (flags & GB_LOCK_NOWAIT) 3510 lockflags |= LK_NOWAIT; 3511 3512 error = BUF_TIMELOCK(bp, lockflags, 3513 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo); 3514 3515 /* 3516 * If we slept and got the lock we have to restart in case 3517 * the buffer changed identities. 3518 */ 3519 if (error == ENOLCK) 3520 goto loop; 3521 /* We timed out or were interrupted. */ 3522 else if (error) 3523 return (NULL); 3524 /* If recursed, assume caller knows the rules. */ 3525 else if (BUF_LOCKRECURSED(bp)) 3526 goto end; 3527 3528 /* 3529 * The buffer is locked. B_CACHE is cleared if the buffer is 3530 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 3531 * and for a VMIO buffer B_CACHE is adjusted according to the 3532 * backing VM cache. 3533 */ 3534 if (bp->b_flags & B_INVAL) 3535 bp->b_flags &= ~B_CACHE; 3536 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 3537 bp->b_flags |= B_CACHE; 3538 if (bp->b_flags & B_MANAGED) 3539 MPASS(bp->b_qindex == QUEUE_NONE); 3540 else 3541 bremfree(bp); 3542 3543 /* 3544 * check for size inconsistencies for non-VMIO case. 3545 */ 3546 if (bp->b_bcount != size) { 3547 if ((bp->b_flags & B_VMIO) == 0 || 3548 (size > bp->b_kvasize)) { 3549 if (bp->b_flags & B_DELWRI) { 3550 /* 3551 * If buffer is pinned and caller does 3552 * not want sleep waiting for it to be 3553 * unpinned, bail out 3554 * */ 3555 if (bp->b_pin_count > 0) { 3556 if (flags & GB_LOCK_NOWAIT) { 3557 bqrelse(bp); 3558 return (NULL); 3559 } else { 3560 bunpin_wait(bp); 3561 } 3562 } 3563 bp->b_flags |= B_NOCACHE; 3564 bwrite(bp); 3565 } else { 3566 if (LIST_EMPTY(&bp->b_dep)) { 3567 bp->b_flags |= B_RELBUF; 3568 brelse(bp); 3569 } else { 3570 bp->b_flags |= B_NOCACHE; 3571 bwrite(bp); 3572 } 3573 } 3574 goto loop; 3575 } 3576 } 3577 3578 /* 3579 * Handle the case of unmapped buffer which should 3580 * become mapped, or the buffer for which KVA 3581 * reservation is requested. 3582 */ 3583 bp_unmapped_get_kva(bp, blkno, size, flags); 3584 3585 /* 3586 * If the size is inconsistent in the VMIO case, we can resize 3587 * the buffer. This might lead to B_CACHE getting set or 3588 * cleared. If the size has not changed, B_CACHE remains 3589 * unchanged from its previous state. 3590 */ 3591 allocbuf(bp, size); 3592 3593 KASSERT(bp->b_offset != NOOFFSET, 3594 ("getblk: no buffer offset")); 3595 3596 /* 3597 * A buffer with B_DELWRI set and B_CACHE clear must 3598 * be committed before we can return the buffer in 3599 * order to prevent the caller from issuing a read 3600 * ( due to B_CACHE not being set ) and overwriting 3601 * it. 3602 * 3603 * Most callers, including NFS and FFS, need this to 3604 * operate properly either because they assume they 3605 * can issue a read if B_CACHE is not set, or because 3606 * ( for example ) an uncached B_DELWRI might loop due 3607 * to softupdates re-dirtying the buffer. In the latter 3608 * case, B_CACHE is set after the first write completes, 3609 * preventing further loops. 3610 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 3611 * above while extending the buffer, we cannot allow the 3612 * buffer to remain with B_CACHE set after the write 3613 * completes or it will represent a corrupt state. To 3614 * deal with this we set B_NOCACHE to scrap the buffer 3615 * after the write. 3616 * 3617 * We might be able to do something fancy, like setting 3618 * B_CACHE in bwrite() except if B_DELWRI is already set, 3619 * so the below call doesn't set B_CACHE, but that gets real 3620 * confusing. This is much easier. 3621 */ 3622 3623 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 3624 bp->b_flags |= B_NOCACHE; 3625 bwrite(bp); 3626 goto loop; 3627 } 3628 bp->b_flags &= ~B_DONE; 3629 } else { 3630 /* 3631 * Buffer is not in-core, create new buffer. The buffer 3632 * returned by getnewbuf() is locked. Note that the returned 3633 * buffer is also considered valid (not marked B_INVAL). 3634 */ 3635 BO_RUNLOCK(bo); 3636 /* 3637 * If the user does not want us to create the buffer, bail out 3638 * here. 3639 */ 3640 if (flags & GB_NOCREAT) 3641 return NULL; 3642 if (numfreebuffers == 0 && TD_IS_IDLETHREAD(curthread)) 3643 return NULL; 3644 3645 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize; 3646 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3647 offset = blkno * bsize; 3648 vmio = vp->v_object != NULL; 3649 if (vmio) { 3650 maxsize = size + (offset & PAGE_MASK); 3651 } else { 3652 maxsize = size; 3653 /* Do not allow non-VMIO notmapped buffers. */ 3654 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3655 } 3656 maxsize = imax(maxsize, bsize); 3657 3658 bp = getnewbuf(vp, slpflag, slptimeo, maxsize, flags); 3659 if (bp == NULL) { 3660 if (slpflag || slptimeo) 3661 return NULL; 3662 /* 3663 * XXX This is here until the sleep path is diagnosed 3664 * enough to work under very low memory conditions. 3665 * 3666 * There's an issue on low memory, 4BSD+non-preempt 3667 * systems (eg MIPS routers with 32MB RAM) where buffer 3668 * exhaustion occurs without sleeping for buffer 3669 * reclaimation. This just sticks in a loop and 3670 * constantly attempts to allocate a buffer, which 3671 * hits exhaustion and tries to wakeup bufdaemon. 3672 * This never happens because we never yield. 3673 * 3674 * The real solution is to identify and fix these cases 3675 * so we aren't effectively busy-waiting in a loop 3676 * until the reclaimation path has cycles to run. 3677 */ 3678 kern_yield(PRI_USER); 3679 goto loop; 3680 } 3681 3682 /* 3683 * This code is used to make sure that a buffer is not 3684 * created while the getnewbuf routine is blocked. 3685 * This can be a problem whether the vnode is locked or not. 3686 * If the buffer is created out from under us, we have to 3687 * throw away the one we just created. 3688 * 3689 * Note: this must occur before we associate the buffer 3690 * with the vp especially considering limitations in 3691 * the splay tree implementation when dealing with duplicate 3692 * lblkno's. 3693 */ 3694 BO_LOCK(bo); 3695 if (gbincore(bo, blkno)) { 3696 BO_UNLOCK(bo); 3697 bp->b_flags |= B_INVAL; 3698 brelse(bp); 3699 bufspace_release(maxsize); 3700 goto loop; 3701 } 3702 3703 /* 3704 * Insert the buffer into the hash, so that it can 3705 * be found by incore. 3706 */ 3707 bp->b_blkno = bp->b_lblkno = blkno; 3708 bp->b_offset = offset; 3709 bgetvp(vp, bp); 3710 BO_UNLOCK(bo); 3711 3712 /* 3713 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 3714 * buffer size starts out as 0, B_CACHE will be set by 3715 * allocbuf() for the VMIO case prior to it testing the 3716 * backing store for validity. 3717 */ 3718 3719 if (vmio) { 3720 bp->b_flags |= B_VMIO; 3721 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 3722 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 3723 bp, vp->v_object, bp->b_bufobj->bo_object)); 3724 } else { 3725 bp->b_flags &= ~B_VMIO; 3726 KASSERT(bp->b_bufobj->bo_object == NULL, 3727 ("ARGH! has b_bufobj->bo_object %p %p\n", 3728 bp, bp->b_bufobj->bo_object)); 3729 BUF_CHECK_MAPPED(bp); 3730 } 3731 3732 allocbuf(bp, size); 3733 bufspace_release(maxsize); 3734 bp->b_flags &= ~B_DONE; 3735 } 3736 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 3737 BUF_ASSERT_HELD(bp); 3738end: 3739 KASSERT(bp->b_bufobj == bo, 3740 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 3741 return (bp); 3742} 3743 3744/* 3745 * Get an empty, disassociated buffer of given size. The buffer is initially 3746 * set to B_INVAL. 3747 */ 3748struct buf * 3749geteblk(int size, int flags) 3750{ 3751 struct buf *bp; 3752 int maxsize; 3753 3754 maxsize = (size + BKVAMASK) & ~BKVAMASK; 3755 while ((bp = getnewbuf(NULL, 0, 0, maxsize, flags)) == NULL) { 3756 if ((flags & GB_NOWAIT_BD) && 3757 (curthread->td_pflags & TDP_BUFNEED) != 0) 3758 return (NULL); 3759 } 3760 allocbuf(bp, size); 3761 bufspace_release(maxsize); 3762 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 3763 BUF_ASSERT_HELD(bp); 3764 return (bp); 3765} 3766 3767/* 3768 * Truncate the backing store for a non-vmio buffer. 3769 */ 3770static void 3771vfs_nonvmio_truncate(struct buf *bp, int newbsize) 3772{ 3773 3774 if (bp->b_flags & B_MALLOC) { 3775 /* 3776 * malloced buffers are not shrunk 3777 */ 3778 if (newbsize == 0) { 3779 bufmallocadjust(bp, 0); 3780 free(bp->b_data, M_BIOBUF); 3781 bp->b_data = bp->b_kvabase; 3782 bp->b_flags &= ~B_MALLOC; 3783 } 3784 return; 3785 } 3786 vm_hold_free_pages(bp, newbsize); 3787 bufspace_adjust(bp, newbsize); 3788} 3789 3790/* 3791 * Extend the backing for a non-VMIO buffer. 3792 */ 3793static void 3794vfs_nonvmio_extend(struct buf *bp, int newbsize) 3795{ 3796 caddr_t origbuf; 3797 int origbufsize; 3798 3799 /* 3800 * We only use malloced memory on the first allocation. 3801 * and revert to page-allocated memory when the buffer 3802 * grows. 3803 * 3804 * There is a potential smp race here that could lead 3805 * to bufmallocspace slightly passing the max. It 3806 * is probably extremely rare and not worth worrying 3807 * over. 3808 */ 3809 if (bp->b_bufsize == 0 && newbsize <= PAGE_SIZE/2 && 3810 bufmallocspace < maxbufmallocspace) { 3811 bp->b_data = malloc(newbsize, M_BIOBUF, M_WAITOK); 3812 bp->b_flags |= B_MALLOC; 3813 bufmallocadjust(bp, newbsize); 3814 return; 3815 } 3816 3817 /* 3818 * If the buffer is growing on its other-than-first 3819 * allocation then we revert to the page-allocation 3820 * scheme. 3821 */ 3822 origbuf = NULL; 3823 origbufsize = 0; 3824 if (bp->b_flags & B_MALLOC) { 3825 origbuf = bp->b_data; 3826 origbufsize = bp->b_bufsize; 3827 bp->b_data = bp->b_kvabase; 3828 bufmallocadjust(bp, 0); 3829 bp->b_flags &= ~B_MALLOC; 3830 newbsize = round_page(newbsize); 3831 } 3832 vm_hold_load_pages(bp, (vm_offset_t) bp->b_data + bp->b_bufsize, 3833 (vm_offset_t) bp->b_data + newbsize); 3834 if (origbuf != NULL) { 3835 bcopy(origbuf, bp->b_data, origbufsize); 3836 free(origbuf, M_BIOBUF); 3837 } 3838 bufspace_adjust(bp, newbsize); 3839} 3840 3841/* 3842 * This code constitutes the buffer memory from either anonymous system 3843 * memory (in the case of non-VMIO operations) or from an associated 3844 * VM object (in the case of VMIO operations). This code is able to 3845 * resize a buffer up or down. 3846 * 3847 * Note that this code is tricky, and has many complications to resolve 3848 * deadlock or inconsistent data situations. Tread lightly!!! 3849 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 3850 * the caller. Calling this code willy nilly can result in the loss of data. 3851 * 3852 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 3853 * B_CACHE for the non-VMIO case. 3854 */ 3855int 3856allocbuf(struct buf *bp, int size) 3857{ 3858 int newbsize; 3859 3860 BUF_ASSERT_HELD(bp); 3861 3862 if (bp->b_bcount == size) 3863 return (1); 3864 3865 if (bp->b_kvasize != 0 && bp->b_kvasize < size) 3866 panic("allocbuf: buffer too small"); 3867 3868 newbsize = roundup2(size, DEV_BSIZE); 3869 if ((bp->b_flags & B_VMIO) == 0) { 3870 if ((bp->b_flags & B_MALLOC) == 0) 3871 newbsize = round_page(newbsize); 3872 /* 3873 * Just get anonymous memory from the kernel. Don't 3874 * mess with B_CACHE. 3875 */ 3876 if (newbsize < bp->b_bufsize) 3877 vfs_nonvmio_truncate(bp, newbsize); 3878 else if (newbsize > bp->b_bufsize) 3879 vfs_nonvmio_extend(bp, newbsize); 3880 } else { 3881 int desiredpages; 3882 3883 desiredpages = (size == 0) ? 0 : 3884 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 3885 3886 if (bp->b_flags & B_MALLOC) 3887 panic("allocbuf: VMIO buffer can't be malloced"); 3888 /* 3889 * Set B_CACHE initially if buffer is 0 length or will become 3890 * 0-length. 3891 */ 3892 if (size == 0 || bp->b_bufsize == 0) 3893 bp->b_flags |= B_CACHE; 3894 3895 if (newbsize < bp->b_bufsize) 3896 vfs_vmio_truncate(bp, desiredpages); 3897 /* XXX This looks as if it should be newbsize > b_bufsize */ 3898 else if (size > bp->b_bcount) 3899 vfs_vmio_extend(bp, desiredpages, size); 3900 bufspace_adjust(bp, newbsize); 3901 } 3902 bp->b_bcount = size; /* requested buffer size. */ 3903 return (1); 3904} 3905 3906extern int inflight_transient_maps; 3907 3908void 3909biodone(struct bio *bp) 3910{ 3911 struct mtx *mtxp; 3912 void (*done)(struct bio *); 3913 vm_offset_t start, end; 3914 3915 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) { 3916 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING; 3917 bp->bio_flags |= BIO_UNMAPPED; 3918 start = trunc_page((vm_offset_t)bp->bio_data); 3919 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length); 3920 bp->bio_data = unmapped_buf; 3921 pmap_qremove(start, atop(end - start)); 3922 vmem_free(transient_arena, start, end - start); 3923 atomic_add_int(&inflight_transient_maps, -1); 3924 } 3925 done = bp->bio_done; 3926 if (done == NULL) { 3927 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3928 mtx_lock(mtxp); 3929 bp->bio_flags |= BIO_DONE; 3930 wakeup(bp); 3931 mtx_unlock(mtxp); 3932 } else 3933 done(bp); 3934} 3935 3936/* 3937 * Wait for a BIO to finish. 3938 */ 3939int 3940biowait(struct bio *bp, const char *wchan) 3941{ 3942 struct mtx *mtxp; 3943 3944 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3945 mtx_lock(mtxp); 3946 while ((bp->bio_flags & BIO_DONE) == 0) 3947 msleep(bp, mtxp, PRIBIO, wchan, 0); 3948 mtx_unlock(mtxp); 3949 if (bp->bio_error != 0) 3950 return (bp->bio_error); 3951 if (!(bp->bio_flags & BIO_ERROR)) 3952 return (0); 3953 return (EIO); 3954} 3955 3956void 3957biofinish(struct bio *bp, struct devstat *stat, int error) 3958{ 3959 3960 if (error) { 3961 bp->bio_error = error; 3962 bp->bio_flags |= BIO_ERROR; 3963 } 3964 if (stat != NULL) 3965 devstat_end_transaction_bio(stat, bp); 3966 biodone(bp); 3967} 3968 3969/* 3970 * bufwait: 3971 * 3972 * Wait for buffer I/O completion, returning error status. The buffer 3973 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3974 * error and cleared. 3975 */ 3976int 3977bufwait(struct buf *bp) 3978{ 3979 if (bp->b_iocmd == BIO_READ) 3980 bwait(bp, PRIBIO, "biord"); 3981 else 3982 bwait(bp, PRIBIO, "biowr"); 3983 if (bp->b_flags & B_EINTR) { 3984 bp->b_flags &= ~B_EINTR; 3985 return (EINTR); 3986 } 3987 if (bp->b_ioflags & BIO_ERROR) { 3988 return (bp->b_error ? bp->b_error : EIO); 3989 } else { 3990 return (0); 3991 } 3992} 3993 3994/* 3995 * bufdone: 3996 * 3997 * Finish I/O on a buffer, optionally calling a completion function. 3998 * This is usually called from an interrupt so process blocking is 3999 * not allowed. 4000 * 4001 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 4002 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 4003 * assuming B_INVAL is clear. 4004 * 4005 * For the VMIO case, we set B_CACHE if the op was a read and no 4006 * read error occurred, or if the op was a write. B_CACHE is never 4007 * set if the buffer is invalid or otherwise uncacheable. 4008 * 4009 * biodone does not mess with B_INVAL, allowing the I/O routine or the 4010 * initiator to leave B_INVAL set to brelse the buffer out of existence 4011 * in the biodone routine. 4012 */ 4013void 4014bufdone(struct buf *bp) 4015{ 4016 struct bufobj *dropobj; 4017 void (*biodone)(struct buf *); 4018 4019 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 4020 dropobj = NULL; 4021 4022 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 4023 BUF_ASSERT_HELD(bp); 4024 4025 runningbufwakeup(bp); 4026 if (bp->b_iocmd == BIO_WRITE) 4027 dropobj = bp->b_bufobj; 4028 /* call optional completion function if requested */ 4029 if (bp->b_iodone != NULL) { 4030 biodone = bp->b_iodone; 4031 bp->b_iodone = NULL; 4032 (*biodone) (bp); 4033 if (dropobj) 4034 bufobj_wdrop(dropobj); 4035 return; 4036 } 4037 4038 bufdone_finish(bp); 4039 4040 if (dropobj) 4041 bufobj_wdrop(dropobj); 4042} 4043 4044void 4045bufdone_finish(struct buf *bp) 4046{ 4047 BUF_ASSERT_HELD(bp); 4048 4049 if (!LIST_EMPTY(&bp->b_dep)) 4050 buf_complete(bp); 4051 4052 if (bp->b_flags & B_VMIO) { 4053 /* 4054 * Set B_CACHE if the op was a normal read and no error 4055 * occurred. B_CACHE is set for writes in the b*write() 4056 * routines. 4057 */ 4058 if (bp->b_iocmd == BIO_READ && 4059 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 4060 !(bp->b_ioflags & BIO_ERROR)) 4061 bp->b_flags |= B_CACHE; 4062 vfs_vmio_iodone(bp); 4063 } 4064 4065 /* 4066 * For asynchronous completions, release the buffer now. The brelse 4067 * will do a wakeup there if necessary - so no need to do a wakeup 4068 * here in the async case. The sync case always needs to do a wakeup. 4069 */ 4070 if (bp->b_flags & B_ASYNC) { 4071 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || 4072 (bp->b_ioflags & BIO_ERROR)) 4073 brelse(bp); 4074 else 4075 bqrelse(bp); 4076 } else 4077 bdone(bp); 4078} 4079 4080/* 4081 * This routine is called in lieu of iodone in the case of 4082 * incomplete I/O. This keeps the busy status for pages 4083 * consistent. 4084 */ 4085void 4086vfs_unbusy_pages(struct buf *bp) 4087{ 4088 int i; 4089 vm_object_t obj; 4090 vm_page_t m; 4091 4092 runningbufwakeup(bp); 4093 if (!(bp->b_flags & B_VMIO)) 4094 return; 4095 4096 obj = bp->b_bufobj->bo_object; 4097 VM_OBJECT_WLOCK(obj); 4098 for (i = 0; i < bp->b_npages; i++) { 4099 m = bp->b_pages[i]; 4100 if (m == bogus_page) { 4101 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 4102 if (!m) 4103 panic("vfs_unbusy_pages: page missing\n"); 4104 bp->b_pages[i] = m; 4105 if (buf_mapped(bp)) { 4106 BUF_CHECK_MAPPED(bp); 4107 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4108 bp->b_pages, bp->b_npages); 4109 } else 4110 BUF_CHECK_UNMAPPED(bp); 4111 } 4112 vm_page_sunbusy(m); 4113 } 4114 vm_object_pip_wakeupn(obj, bp->b_npages); 4115 VM_OBJECT_WUNLOCK(obj); 4116} 4117 4118/* 4119 * vfs_page_set_valid: 4120 * 4121 * Set the valid bits in a page based on the supplied offset. The 4122 * range is restricted to the buffer's size. 4123 * 4124 * This routine is typically called after a read completes. 4125 */ 4126static void 4127vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4128{ 4129 vm_ooffset_t eoff; 4130 4131 /* 4132 * Compute the end offset, eoff, such that [off, eoff) does not span a 4133 * page boundary and eoff is not greater than the end of the buffer. 4134 * The end of the buffer, in this case, is our file EOF, not the 4135 * allocation size of the buffer. 4136 */ 4137 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 4138 if (eoff > bp->b_offset + bp->b_bcount) 4139 eoff = bp->b_offset + bp->b_bcount; 4140 4141 /* 4142 * Set valid range. This is typically the entire buffer and thus the 4143 * entire page. 4144 */ 4145 if (eoff > off) 4146 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off); 4147} 4148 4149/* 4150 * vfs_page_set_validclean: 4151 * 4152 * Set the valid bits and clear the dirty bits in a page based on the 4153 * supplied offset. The range is restricted to the buffer's size. 4154 */ 4155static void 4156vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4157{ 4158 vm_ooffset_t soff, eoff; 4159 4160 /* 4161 * Start and end offsets in buffer. eoff - soff may not cross a 4162 * page boundary or cross the end of the buffer. The end of the 4163 * buffer, in this case, is our file EOF, not the allocation size 4164 * of the buffer. 4165 */ 4166 soff = off; 4167 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4168 if (eoff > bp->b_offset + bp->b_bcount) 4169 eoff = bp->b_offset + bp->b_bcount; 4170 4171 /* 4172 * Set valid range. This is typically the entire buffer and thus the 4173 * entire page. 4174 */ 4175 if (eoff > soff) { 4176 vm_page_set_validclean( 4177 m, 4178 (vm_offset_t) (soff & PAGE_MASK), 4179 (vm_offset_t) (eoff - soff) 4180 ); 4181 } 4182} 4183 4184/* 4185 * Ensure that all buffer pages are not exclusive busied. If any page is 4186 * exclusive busy, drain it. 4187 */ 4188void 4189vfs_drain_busy_pages(struct buf *bp) 4190{ 4191 vm_page_t m; 4192 int i, last_busied; 4193 4194 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object); 4195 last_busied = 0; 4196 for (i = 0; i < bp->b_npages; i++) { 4197 m = bp->b_pages[i]; 4198 if (vm_page_xbusied(m)) { 4199 for (; last_busied < i; last_busied++) 4200 vm_page_sbusy(bp->b_pages[last_busied]); 4201 while (vm_page_xbusied(m)) { 4202 vm_page_lock(m); 4203 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4204 vm_page_busy_sleep(m, "vbpage", true); 4205 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4206 } 4207 } 4208 } 4209 for (i = 0; i < last_busied; i++) 4210 vm_page_sunbusy(bp->b_pages[i]); 4211} 4212 4213/* 4214 * This routine is called before a device strategy routine. 4215 * It is used to tell the VM system that paging I/O is in 4216 * progress, and treat the pages associated with the buffer 4217 * almost as being exclusive busy. Also the object paging_in_progress 4218 * flag is handled to make sure that the object doesn't become 4219 * inconsistent. 4220 * 4221 * Since I/O has not been initiated yet, certain buffer flags 4222 * such as BIO_ERROR or B_INVAL may be in an inconsistent state 4223 * and should be ignored. 4224 */ 4225void 4226vfs_busy_pages(struct buf *bp, int clear_modify) 4227{ 4228 int i, bogus; 4229 vm_object_t obj; 4230 vm_ooffset_t foff; 4231 vm_page_t m; 4232 4233 if (!(bp->b_flags & B_VMIO)) 4234 return; 4235 4236 obj = bp->b_bufobj->bo_object; 4237 foff = bp->b_offset; 4238 KASSERT(bp->b_offset != NOOFFSET, 4239 ("vfs_busy_pages: no buffer offset")); 4240 VM_OBJECT_WLOCK(obj); 4241 vfs_drain_busy_pages(bp); 4242 if (bp->b_bufsize != 0) 4243 vfs_setdirty_locked_object(bp); 4244 bogus = 0; 4245 for (i = 0; i < bp->b_npages; i++) { 4246 m = bp->b_pages[i]; 4247 4248 if ((bp->b_flags & B_CLUSTER) == 0) { 4249 vm_object_pip_add(obj, 1); 4250 vm_page_sbusy(m); 4251 } 4252 /* 4253 * When readying a buffer for a read ( i.e 4254 * clear_modify == 0 ), it is important to do 4255 * bogus_page replacement for valid pages in 4256 * partially instantiated buffers. Partially 4257 * instantiated buffers can, in turn, occur when 4258 * reconstituting a buffer from its VM backing store 4259 * base. We only have to do this if B_CACHE is 4260 * clear ( which causes the I/O to occur in the 4261 * first place ). The replacement prevents the read 4262 * I/O from overwriting potentially dirty VM-backed 4263 * pages. XXX bogus page replacement is, uh, bogus. 4264 * It may not work properly with small-block devices. 4265 * We need to find a better way. 4266 */ 4267 if (clear_modify) { 4268 pmap_remove_write(m); 4269 vfs_page_set_validclean(bp, foff, m); 4270 } else if (m->valid == VM_PAGE_BITS_ALL && 4271 (bp->b_flags & B_CACHE) == 0) { 4272 bp->b_pages[i] = bogus_page; 4273 bogus++; 4274 } 4275 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4276 } 4277 VM_OBJECT_WUNLOCK(obj); 4278 if (bogus && buf_mapped(bp)) { 4279 BUF_CHECK_MAPPED(bp); 4280 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4281 bp->b_pages, bp->b_npages); 4282 } 4283} 4284 4285/* 4286 * vfs_bio_set_valid: 4287 * 4288 * Set the range within the buffer to valid. The range is 4289 * relative to the beginning of the buffer, b_offset. Note that 4290 * b_offset itself may be offset from the beginning of the first 4291 * page. 4292 */ 4293void 4294vfs_bio_set_valid(struct buf *bp, int base, int size) 4295{ 4296 int i, n; 4297 vm_page_t m; 4298 4299 if (!(bp->b_flags & B_VMIO)) 4300 return; 4301 4302 /* 4303 * Fixup base to be relative to beginning of first page. 4304 * Set initial n to be the maximum number of bytes in the 4305 * first page that can be validated. 4306 */ 4307 base += (bp->b_offset & PAGE_MASK); 4308 n = PAGE_SIZE - (base & PAGE_MASK); 4309 4310 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4311 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4312 m = bp->b_pages[i]; 4313 if (n > size) 4314 n = size; 4315 vm_page_set_valid_range(m, base & PAGE_MASK, n); 4316 base += n; 4317 size -= n; 4318 n = PAGE_SIZE; 4319 } 4320 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4321} 4322 4323/* 4324 * vfs_bio_clrbuf: 4325 * 4326 * If the specified buffer is a non-VMIO buffer, clear the entire 4327 * buffer. If the specified buffer is a VMIO buffer, clear and 4328 * validate only the previously invalid portions of the buffer. 4329 * This routine essentially fakes an I/O, so we need to clear 4330 * BIO_ERROR and B_INVAL. 4331 * 4332 * Note that while we only theoretically need to clear through b_bcount, 4333 * we go ahead and clear through b_bufsize. 4334 */ 4335void 4336vfs_bio_clrbuf(struct buf *bp) 4337{ 4338 int i, j, mask, sa, ea, slide; 4339 4340 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 4341 clrbuf(bp); 4342 return; 4343 } 4344 bp->b_flags &= ~B_INVAL; 4345 bp->b_ioflags &= ~BIO_ERROR; 4346 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4347 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 4348 (bp->b_offset & PAGE_MASK) == 0) { 4349 if (bp->b_pages[0] == bogus_page) 4350 goto unlock; 4351 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 4352 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object); 4353 if ((bp->b_pages[0]->valid & mask) == mask) 4354 goto unlock; 4355 if ((bp->b_pages[0]->valid & mask) == 0) { 4356 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize); 4357 bp->b_pages[0]->valid |= mask; 4358 goto unlock; 4359 } 4360 } 4361 sa = bp->b_offset & PAGE_MASK; 4362 slide = 0; 4363 for (i = 0; i < bp->b_npages; i++, sa = 0) { 4364 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize); 4365 ea = slide & PAGE_MASK; 4366 if (ea == 0) 4367 ea = PAGE_SIZE; 4368 if (bp->b_pages[i] == bogus_page) 4369 continue; 4370 j = sa / DEV_BSIZE; 4371 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 4372 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object); 4373 if ((bp->b_pages[i]->valid & mask) == mask) 4374 continue; 4375 if ((bp->b_pages[i]->valid & mask) == 0) 4376 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa); 4377 else { 4378 for (; sa < ea; sa += DEV_BSIZE, j++) { 4379 if ((bp->b_pages[i]->valid & (1 << j)) == 0) { 4380 pmap_zero_page_area(bp->b_pages[i], 4381 sa, DEV_BSIZE); 4382 } 4383 } 4384 } 4385 bp->b_pages[i]->valid |= mask; 4386 } 4387unlock: 4388 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4389 bp->b_resid = 0; 4390} 4391 4392void 4393vfs_bio_bzero_buf(struct buf *bp, int base, int size) 4394{ 4395 vm_page_t m; 4396 int i, n; 4397 4398 if (buf_mapped(bp)) { 4399 BUF_CHECK_MAPPED(bp); 4400 bzero(bp->b_data + base, size); 4401 } else { 4402 BUF_CHECK_UNMAPPED(bp); 4403 n = PAGE_SIZE - (base & PAGE_MASK); 4404 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4405 m = bp->b_pages[i]; 4406 if (n > size) 4407 n = size; 4408 pmap_zero_page_area(m, base & PAGE_MASK, n); 4409 base += n; 4410 size -= n; 4411 n = PAGE_SIZE; 4412 } 4413 } 4414} 4415 4416/* 4417 * vm_hold_load_pages and vm_hold_free_pages get pages into 4418 * a buffers address space. The pages are anonymous and are 4419 * not associated with a file object. 4420 */ 4421static void 4422vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4423{ 4424 vm_offset_t pg; 4425 vm_page_t p; 4426 int index; 4427 4428 BUF_CHECK_MAPPED(bp); 4429 4430 to = round_page(to); 4431 from = round_page(from); 4432 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4433 4434 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 4435tryagain: 4436 /* 4437 * note: must allocate system pages since blocking here 4438 * could interfere with paging I/O, no matter which 4439 * process we are. 4440 */ 4441 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ | 4442 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT)); 4443 if (p == NULL) { 4444 VM_WAIT; 4445 goto tryagain; 4446 } 4447 pmap_qenter(pg, &p, 1); 4448 bp->b_pages[index] = p; 4449 } 4450 bp->b_npages = index; 4451} 4452 4453/* Return pages associated with this buf to the vm system */ 4454static void 4455vm_hold_free_pages(struct buf *bp, int newbsize) 4456{ 4457 vm_offset_t from; 4458 vm_page_t p; 4459 int index, newnpages; 4460 4461 BUF_CHECK_MAPPED(bp); 4462 4463 from = round_page((vm_offset_t)bp->b_data + newbsize); 4464 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4465 if (bp->b_npages > newnpages) 4466 pmap_qremove(from, bp->b_npages - newnpages); 4467 for (index = newnpages; index < bp->b_npages; index++) { 4468 p = bp->b_pages[index]; 4469 bp->b_pages[index] = NULL; 4470 if (vm_page_sbusied(p)) 4471 printf("vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 4472 (intmax_t)bp->b_blkno, (intmax_t)bp->b_lblkno); 4473 p->wire_count--; 4474 vm_page_free(p); 4475 atomic_subtract_int(&vm_cnt.v_wire_count, 1); 4476 } 4477 bp->b_npages = newnpages; 4478} 4479 4480/* 4481 * Map an IO request into kernel virtual address space. 4482 * 4483 * All requests are (re)mapped into kernel VA space. 4484 * Notice that we use b_bufsize for the size of the buffer 4485 * to be mapped. b_bcount might be modified by the driver. 4486 * 4487 * Note that even if the caller determines that the address space should 4488 * be valid, a race or a smaller-file mapped into a larger space may 4489 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 4490 * check the return value. 4491 * 4492 * This function only works with pager buffers. 4493 */ 4494int 4495vmapbuf(struct buf *bp, int mapbuf) 4496{ 4497 vm_prot_t prot; 4498 int pidx; 4499 4500 if (bp->b_bufsize < 0) 4501 return (-1); 4502 prot = VM_PROT_READ; 4503 if (bp->b_iocmd == BIO_READ) 4504 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 4505 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 4506 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages, 4507 btoc(MAXPHYS))) < 0) 4508 return (-1); 4509 bp->b_npages = pidx; 4510 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK; 4511 if (mapbuf || !unmapped_buf_allowed) { 4512 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_pages, pidx); 4513 bp->b_data = bp->b_kvabase + bp->b_offset; 4514 } else 4515 bp->b_data = unmapped_buf; 4516 return(0); 4517} 4518 4519/* 4520 * Free the io map PTEs associated with this IO operation. 4521 * We also invalidate the TLB entries and restore the original b_addr. 4522 * 4523 * This function only works with pager buffers. 4524 */ 4525void 4526vunmapbuf(struct buf *bp) 4527{ 4528 int npages; 4529 4530 npages = bp->b_npages; 4531 if (buf_mapped(bp)) 4532 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 4533 vm_page_unhold_pages(bp->b_pages, npages); 4534 4535 bp->b_data = unmapped_buf; 4536} 4537 4538void 4539bdone(struct buf *bp) 4540{ 4541 struct mtx *mtxp; 4542 4543 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4544 mtx_lock(mtxp); 4545 bp->b_flags |= B_DONE; 4546 wakeup(bp); 4547 mtx_unlock(mtxp); 4548} 4549 4550void 4551bwait(struct buf *bp, u_char pri, const char *wchan) 4552{ 4553 struct mtx *mtxp; 4554 4555 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4556 mtx_lock(mtxp); 4557 while ((bp->b_flags & B_DONE) == 0) 4558 msleep(bp, mtxp, pri, wchan, 0); 4559 mtx_unlock(mtxp); 4560} 4561 4562int 4563bufsync(struct bufobj *bo, int waitfor) 4564{ 4565 4566 return (VOP_FSYNC(bo->__bo_vnode, waitfor, curthread)); 4567} 4568 4569void 4570bufstrategy(struct bufobj *bo, struct buf *bp) 4571{ 4572 int i = 0; 4573 struct vnode *vp; 4574 4575 vp = bp->b_vp; 4576 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 4577 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 4578 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 4579 i = VOP_STRATEGY(vp, bp); 4580 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 4581} 4582 4583void 4584bufobj_wrefl(struct bufobj *bo) 4585{ 4586 4587 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4588 ASSERT_BO_WLOCKED(bo); 4589 bo->bo_numoutput++; 4590} 4591 4592void 4593bufobj_wref(struct bufobj *bo) 4594{ 4595 4596 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4597 BO_LOCK(bo); 4598 bo->bo_numoutput++; 4599 BO_UNLOCK(bo); 4600} 4601 4602void 4603bufobj_wdrop(struct bufobj *bo) 4604{ 4605 4606 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 4607 BO_LOCK(bo); 4608 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 4609 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 4610 bo->bo_flag &= ~BO_WWAIT; 4611 wakeup(&bo->bo_numoutput); 4612 } 4613 BO_UNLOCK(bo); 4614} 4615 4616int 4617bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 4618{ 4619 int error; 4620 4621 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 4622 ASSERT_BO_WLOCKED(bo); 4623 error = 0; 4624 while (bo->bo_numoutput) { 4625 bo->bo_flag |= BO_WWAIT; 4626 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo), 4627 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 4628 if (error) 4629 break; 4630 } 4631 return (error); 4632} 4633 4634void 4635bpin(struct buf *bp) 4636{ 4637 struct mtx *mtxp; 4638 4639 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4640 mtx_lock(mtxp); 4641 bp->b_pin_count++; 4642 mtx_unlock(mtxp); 4643} 4644 4645void 4646bunpin(struct buf *bp) 4647{ 4648 struct mtx *mtxp; 4649 4650 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4651 mtx_lock(mtxp); 4652 if (--bp->b_pin_count == 0) 4653 wakeup(bp); 4654 mtx_unlock(mtxp); 4655} 4656 4657void 4658bunpin_wait(struct buf *bp) 4659{ 4660 struct mtx *mtxp; 4661 4662 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4663 mtx_lock(mtxp); 4664 while (bp->b_pin_count > 0) 4665 msleep(bp, mtxp, PRIBIO, "bwunpin", 0); 4666 mtx_unlock(mtxp); 4667} 4668 4669/* 4670 * Set bio_data or bio_ma for struct bio from the struct buf. 4671 */ 4672void 4673bdata2bio(struct buf *bp, struct bio *bip) 4674{ 4675 4676 if (!buf_mapped(bp)) { 4677 KASSERT(unmapped_buf_allowed, ("unmapped")); 4678 bip->bio_ma = bp->b_pages; 4679 bip->bio_ma_n = bp->b_npages; 4680 bip->bio_data = unmapped_buf; 4681 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 4682 bip->bio_flags |= BIO_UNMAPPED; 4683 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) / 4684 PAGE_SIZE == bp->b_npages, 4685 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset, 4686 (long long)bip->bio_length, bip->bio_ma_n)); 4687 } else { 4688 bip->bio_data = bp->b_data; 4689 bip->bio_ma = NULL; 4690 } 4691} 4692 4693static int buf_pager_relbuf; 4694SYSCTL_INT(_vfs, OID_AUTO, buf_pager_relbuf, CTLFLAG_RWTUN, 4695 &buf_pager_relbuf, 0, 4696 "Make buffer pager release buffers after reading"); 4697 4698/* 4699 * The buffer pager. It uses buffer reads to validate pages. 4700 * 4701 * In contrast to the generic local pager from vm/vnode_pager.c, this 4702 * pager correctly and easily handles volumes where the underlying 4703 * device block size is greater than the machine page size. The 4704 * buffer cache transparently extends the requested page run to be 4705 * aligned at the block boundary, and does the necessary bogus page 4706 * replacements in the addends to avoid obliterating already valid 4707 * pages. 4708 * 4709 * The only non-trivial issue is that the exclusive busy state for 4710 * pages, which is assumed by the vm_pager_getpages() interface, is 4711 * incompatible with the VMIO buffer cache's desire to share-busy the 4712 * pages. This function performs a trivial downgrade of the pages' 4713 * state before reading buffers, and a less trivial upgrade from the 4714 * shared-busy to excl-busy state after the read. 4715 */ 4716int 4717vfs_bio_getpages(struct vnode *vp, vm_page_t *ma, int count, 4718 int *rbehind, int *rahead, vbg_get_lblkno_t get_lblkno, 4719 vbg_get_blksize_t get_blksize) 4720{ 4721 vm_page_t m; 4722 vm_object_t object; 4723 struct buf *bp; 4724 struct mount *mp; 4725 daddr_t lbn, lbnp; 4726 vm_ooffset_t la, lb, poff, poffe; 4727 long bsize; 4728 int bo_bs, br_flags, error, i, pgsin, pgsin_a, pgsin_b; 4729 bool redo, lpart; 4730 4731 object = vp->v_object; 4732 mp = vp->v_mount; 4733 la = IDX_TO_OFF(ma[count - 1]->pindex); 4734 if (la >= object->un_pager.vnp.vnp_size) 4735 return (VM_PAGER_BAD); 4736 lpart = la + PAGE_SIZE > object->un_pager.vnp.vnp_size; 4737 bo_bs = get_blksize(vp, get_lblkno(vp, IDX_TO_OFF(ma[0]->pindex))); 4738 4739 /* 4740 * Calculate read-ahead, behind and total pages. 4741 */ 4742 pgsin = count; 4743 lb = IDX_TO_OFF(ma[0]->pindex); 4744 pgsin_b = OFF_TO_IDX(lb - rounddown2(lb, bo_bs)); 4745 pgsin += pgsin_b; 4746 if (rbehind != NULL) 4747 *rbehind = pgsin_b; 4748 pgsin_a = OFF_TO_IDX(roundup2(la, bo_bs) - la); 4749 if (la + IDX_TO_OFF(pgsin_a) >= object->un_pager.vnp.vnp_size) 4750 pgsin_a = OFF_TO_IDX(roundup2(object->un_pager.vnp.vnp_size, 4751 PAGE_SIZE) - la); 4752 pgsin += pgsin_a; 4753 if (rahead != NULL) 4754 *rahead = pgsin_a; 4755 PCPU_INC(cnt.v_vnodein); 4756 PCPU_ADD(cnt.v_vnodepgsin, pgsin); 4757 4758 br_flags = (mp != NULL && (mp->mnt_kern_flag & MNTK_UNMAPPED_BUFS) 4759 != 0) ? GB_UNMAPPED : 0; 4760 VM_OBJECT_WLOCK(object); 4761again: 4762 for (i = 0; i < count; i++) 4763 vm_page_busy_downgrade(ma[i]); 4764 VM_OBJECT_WUNLOCK(object); 4765 4766 lbnp = -1; 4767 for (i = 0; i < count; i++) { 4768 m = ma[i]; 4769 4770 /* 4771 * Pages are shared busy and the object lock is not 4772 * owned, which together allow for the pages' 4773 * invalidation. The racy test for validity avoids 4774 * useless creation of the buffer for the most typical 4775 * case when invalidation is not used in redo or for 4776 * parallel read. The shared->excl upgrade loop at 4777 * the end of the function catches the race in a 4778 * reliable way (protected by the object lock). 4779 */ 4780 if (m->valid == VM_PAGE_BITS_ALL) 4781 continue; 4782 4783 poff = IDX_TO_OFF(m->pindex); 4784 poffe = MIN(poff + PAGE_SIZE, object->un_pager.vnp.vnp_size); 4785 for (; poff < poffe; poff += bsize) { 4786 lbn = get_lblkno(vp, poff); 4787 if (lbn == lbnp) 4788 goto next_page; 4789 lbnp = lbn; 4790 4791 bsize = get_blksize(vp, lbn); 4792 error = bread_gb(vp, lbn, bsize, curthread->td_ucred, 4793 br_flags, &bp); 4794 if (error != 0) 4795 goto end_pages; 4796 if (LIST_EMPTY(&bp->b_dep)) { 4797 /* 4798 * Invalidation clears m->valid, but 4799 * may leave B_CACHE flag if the 4800 * buffer existed at the invalidation 4801 * time. In this case, recycle the 4802 * buffer to do real read on next 4803 * bread() after redo. 4804 * 4805 * Otherwise B_RELBUF is not strictly 4806 * necessary, enable to reduce buf 4807 * cache pressure. 4808 */ 4809 if (buf_pager_relbuf || 4810 m->valid != VM_PAGE_BITS_ALL) 4811 bp->b_flags |= B_RELBUF; 4812 4813 bp->b_flags &= ~B_NOCACHE; 4814 brelse(bp); 4815 } else { 4816 bqrelse(bp); 4817 } 4818 } 4819 KASSERT(1 /* racy, enable for debugging */ || 4820 m->valid == VM_PAGE_BITS_ALL || i == count - 1, 4821 ("buf %d %p invalid", i, m)); 4822 if (i == count - 1 && lpart) { 4823 VM_OBJECT_WLOCK(object); 4824 if (m->valid != 0 && 4825 m->valid != VM_PAGE_BITS_ALL) 4826 vm_page_zero_invalid(m, TRUE); 4827 VM_OBJECT_WUNLOCK(object); 4828 } 4829next_page:; 4830 } 4831end_pages: 4832 4833 VM_OBJECT_WLOCK(object); 4834 redo = false; 4835 for (i = 0; i < count; i++) { 4836 vm_page_sunbusy(ma[i]); 4837 ma[i] = vm_page_grab(object, ma[i]->pindex, VM_ALLOC_NORMAL); 4838 4839 /* 4840 * Since the pages were only sbusy while neither the 4841 * buffer nor the object lock was held by us, or 4842 * reallocated while vm_page_grab() slept for busy 4843 * relinguish, they could have been invalidated. 4844 * Recheck the valid bits and re-read as needed. 4845 * 4846 * Note that the last page is made fully valid in the 4847 * read loop, and partial validity for the page at 4848 * index count - 1 could mean that the page was 4849 * invalidated or removed, so we must restart for 4850 * safety as well. 4851 */ 4852 if (ma[i]->valid != VM_PAGE_BITS_ALL) 4853 redo = true; 4854 } 4855 if (redo && error == 0) 4856 goto again; 4857 VM_OBJECT_WUNLOCK(object); 4858 return (error != 0 ? VM_PAGER_ERROR : VM_PAGER_OK); 4859} 4860 4861#include "opt_ddb.h" 4862#ifdef DDB 4863#include <ddb/ddb.h> 4864 4865/* DDB command to show buffer data */ 4866DB_SHOW_COMMAND(buffer, db_show_buffer) 4867{ 4868 /* get args */ 4869 struct buf *bp = (struct buf *)addr; 4870 4871 if (!have_addr) { 4872 db_printf("usage: show buffer <addr>\n"); 4873 return; 4874 } 4875 4876 db_printf("buf at %p\n", bp); 4877 db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n", 4878 (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags, 4879 PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS); 4880 db_printf( 4881 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 4882 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, " 4883 "b_dep = %p\n", 4884 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 4885 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 4886 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first); 4887 db_printf("b_kvabase = %p, b_kvasize = %d\n", 4888 bp->b_kvabase, bp->b_kvasize); 4889 if (bp->b_npages) { 4890 int i; 4891 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 4892 for (i = 0; i < bp->b_npages; i++) { 4893 vm_page_t m; 4894 m = bp->b_pages[i]; 4895 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 4896 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 4897 if ((i + 1) < bp->b_npages) 4898 db_printf(","); 4899 } 4900 db_printf("\n"); 4901 } 4902 db_printf(" "); 4903 BUF_LOCKPRINTINFO(bp); 4904} 4905 4906DB_SHOW_COMMAND(lockedbufs, lockedbufs) 4907{ 4908 struct buf *bp; 4909 int i; 4910 4911 for (i = 0; i < nbuf; i++) { 4912 bp = &buf[i]; 4913 if (BUF_ISLOCKED(bp)) { 4914 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4915 db_printf("\n"); 4916 } 4917 } 4918} 4919 4920DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 4921{ 4922 struct vnode *vp; 4923 struct buf *bp; 4924 4925 if (!have_addr) { 4926 db_printf("usage: show vnodebufs <addr>\n"); 4927 return; 4928 } 4929 vp = (struct vnode *)addr; 4930 db_printf("Clean buffers:\n"); 4931 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 4932 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4933 db_printf("\n"); 4934 } 4935 db_printf("Dirty buffers:\n"); 4936 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 4937 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4938 db_printf("\n"); 4939 } 4940} 4941 4942DB_COMMAND(countfreebufs, db_coundfreebufs) 4943{ 4944 struct buf *bp; 4945 int i, used = 0, nfree = 0; 4946 4947 if (have_addr) { 4948 db_printf("usage: countfreebufs\n"); 4949 return; 4950 } 4951 4952 for (i = 0; i < nbuf; i++) { 4953 bp = &buf[i]; 4954 if (bp->b_qindex == QUEUE_EMPTY) 4955 nfree++; 4956 else 4957 used++; 4958 } 4959 4960 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 4961 nfree + used); 4962 db_printf("numfreebuffers is %d\n", numfreebuffers); 4963} 4964#endif /* DDB */ 4965