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 367145 2020-10-29 22:00:15Z brooks $"); 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); 134static void maxbcachebuf_adjust(void); 135 136#if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 137 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 138static int sysctl_bufspace(SYSCTL_HANDLER_ARGS); 139#endif 140 141int vmiodirenable = TRUE; 142SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, 143 "Use the VM system for directory writes"); 144long runningbufspace; 145SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 146 "Amount of presently outstanding async buffer io"); 147static long bufspace; 148#if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 149 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 150SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD, 151 &bufspace, 0, sysctl_bufspace, "L", "Virtual memory used for buffers"); 152#else 153SYSCTL_LONG(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, 154 "Physical memory used for buffers"); 155#endif 156static long bufkvaspace; 157SYSCTL_LONG(_vfs, OID_AUTO, bufkvaspace, CTLFLAG_RD, &bufkvaspace, 0, 158 "Kernel virtual memory used for buffers"); 159static long maxbufspace; 160SYSCTL_LONG(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RW, &maxbufspace, 0, 161 "Maximum allowed value of bufspace (including metadata)"); 162static long bufmallocspace; 163SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 164 "Amount of malloced memory for buffers"); 165static long maxbufmallocspace; 166SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 167 0, "Maximum amount of malloced memory for buffers"); 168static long lobufspace; 169SYSCTL_LONG(_vfs, OID_AUTO, lobufspace, CTLFLAG_RW, &lobufspace, 0, 170 "Minimum amount of buffers we want to have"); 171long hibufspace; 172SYSCTL_LONG(_vfs, OID_AUTO, hibufspace, CTLFLAG_RW, &hibufspace, 0, 173 "Maximum allowed value of bufspace (excluding metadata)"); 174long bufspacethresh; 175SYSCTL_LONG(_vfs, OID_AUTO, bufspacethresh, CTLFLAG_RW, &bufspacethresh, 176 0, "Bufspace consumed before waking the daemon to free some"); 177static int buffreekvacnt; 178SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0, 179 "Number of times we have freed the KVA space from some buffer"); 180static int bufdefragcnt; 181SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0, 182 "Number of times we have had to repeat buffer allocation to defragment"); 183static long lorunningspace; 184SYSCTL_PROC(_vfs, OID_AUTO, lorunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE | 185 CTLFLAG_RW, &lorunningspace, 0, sysctl_runningspace, "L", 186 "Minimum preferred space used for in-progress I/O"); 187static long hirunningspace; 188SYSCTL_PROC(_vfs, OID_AUTO, hirunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE | 189 CTLFLAG_RW, &hirunningspace, 0, sysctl_runningspace, "L", 190 "Maximum amount of space to use for in-progress I/O"); 191int dirtybufferflushes; 192SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes, 193 0, "Number of bdwrite to bawrite conversions to limit dirty buffers"); 194int bdwriteskip; 195SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip, 196 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk"); 197int altbufferflushes; 198SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes, 199 0, "Number of fsync flushes to limit dirty buffers"); 200static int recursiveflushes; 201SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes, 202 0, "Number of flushes skipped due to being recursive"); 203static int numdirtybuffers; 204SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0, 205 "Number of buffers that are dirty (has unwritten changes) at the moment"); 206static int lodirtybuffers; 207SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0, 208 "How many buffers we want to have free before bufdaemon can sleep"); 209static int hidirtybuffers; 210SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0, 211 "When the number of dirty buffers is considered severe"); 212int dirtybufthresh; 213SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh, 214 0, "Number of bdwrite to bawrite conversions to clear dirty buffers"); 215static int numfreebuffers; 216SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, 217 "Number of free buffers"); 218static int lofreebuffers; 219SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0, 220 "Target number of free buffers"); 221static int hifreebuffers; 222SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0, 223 "Threshold for clean buffer recycling"); 224static int getnewbufcalls; 225SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0, 226 "Number of calls to getnewbuf"); 227static int getnewbufrestarts; 228SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0, 229 "Number of times getnewbuf has had to restart a buffer acquisition"); 230static int mappingrestarts; 231SYSCTL_INT(_vfs, OID_AUTO, mappingrestarts, CTLFLAG_RW, &mappingrestarts, 0, 232 "Number of times getblk has had to restart a buffer mapping for " 233 "unmapped buffer"); 234static int numbufallocfails; 235SYSCTL_INT(_vfs, OID_AUTO, numbufallocfails, CTLFLAG_RW, &numbufallocfails, 0, 236 "Number of times buffer allocations failed"); 237static int flushbufqtarget = 100; 238SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0, 239 "Amount of work to do in flushbufqueues when helping bufdaemon"); 240static long notbufdflushes; 241SYSCTL_LONG(_vfs, OID_AUTO, notbufdflushes, CTLFLAG_RD, ¬bufdflushes, 0, 242 "Number of dirty buffer flushes done by the bufdaemon helpers"); 243static long barrierwrites; 244SYSCTL_LONG(_vfs, OID_AUTO, barrierwrites, CTLFLAG_RW, &barrierwrites, 0, 245 "Number of barrier writes"); 246SYSCTL_INT(_vfs, OID_AUTO, unmapped_buf_allowed, CTLFLAG_RD, 247 &unmapped_buf_allowed, 0, 248 "Permit the use of the unmapped i/o"); 249int maxbcachebuf = MAXBCACHEBUF; 250SYSCTL_INT(_vfs, OID_AUTO, maxbcachebuf, CTLFLAG_RDTUN, &maxbcachebuf, 0, 251 "Maximum size of a buffer cache block"); 252 253/* 254 * This lock synchronizes access to bd_request. 255 */ 256static struct mtx_padalign __exclusive_cache_line bdlock; 257 258/* 259 * This lock protects the runningbufreq and synchronizes runningbufwakeup and 260 * waitrunningbufspace(). 261 */ 262static struct mtx_padalign __exclusive_cache_line rbreqlock; 263 264/* 265 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it. 266 */ 267static struct rwlock_padalign __exclusive_cache_line nblock; 268 269/* 270 * Lock that protects bdirtywait. 271 */ 272static struct mtx_padalign __exclusive_cache_line bdirtylock; 273 274/* 275 * Wakeup point for bufdaemon, as well as indicator of whether it is already 276 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it 277 * is idling. 278 */ 279static int bd_request; 280 281/* 282 * Request/wakeup point for the bufspace daemon. 283 */ 284static int bufspace_request; 285 286/* 287 * Request for the buf daemon to write more buffers than is indicated by 288 * lodirtybuf. This may be necessary to push out excess dependencies or 289 * defragment the address space where a simple count of the number of dirty 290 * buffers is insufficient to characterize the demand for flushing them. 291 */ 292static int bd_speedupreq; 293 294/* 295 * bogus page -- for I/O to/from partially complete buffers 296 * this is a temporary solution to the problem, but it is not 297 * really that bad. it would be better to split the buffer 298 * for input in the case of buffers partially already in memory, 299 * but the code is intricate enough already. 300 */ 301vm_page_t bogus_page; 302 303/* 304 * Synchronization (sleep/wakeup) variable for active buffer space requests. 305 * Set when wait starts, cleared prior to wakeup(). 306 * Used in runningbufwakeup() and waitrunningbufspace(). 307 */ 308static int runningbufreq; 309 310/* 311 * Synchronization (sleep/wakeup) variable for buffer requests. 312 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done 313 * by and/or. 314 * Used in numdirtywakeup(), bufspace_wakeup(), bwillwrite(), 315 * getnewbuf(), and getblk(). 316 */ 317static volatile int needsbuffer; 318 319/* 320 * Synchronization for bwillwrite() waiters. 321 */ 322static int bdirtywait; 323 324/* 325 * Definitions for the buffer free lists. 326 */ 327#define QUEUE_NONE 0 /* on no queue */ 328#define QUEUE_EMPTY 1 /* empty buffer headers */ 329#define QUEUE_DIRTY 2 /* B_DELWRI buffers */ 330#define QUEUE_CLEAN 3 /* non-B_DELWRI buffers */ 331#define QUEUE_SENTINEL 1024 /* not an queue index, but mark for sentinel */ 332 333/* Maximum number of clean buffer queues. */ 334#define CLEAN_QUEUES 16 335 336/* Configured number of clean queues. */ 337static int clean_queues; 338 339/* Maximum number of buffer queues. */ 340#define BUFFER_QUEUES (QUEUE_CLEAN + CLEAN_QUEUES) 341 342/* Queues for free buffers with various properties */ 343static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } }; 344#ifdef INVARIANTS 345static int bq_len[BUFFER_QUEUES]; 346#endif 347 348/* 349 * Lock for each bufqueue 350 */ 351static struct mtx_padalign __exclusive_cache_line bqlocks[BUFFER_QUEUES]; 352 353/* 354 * per-cpu empty buffer cache. 355 */ 356uma_zone_t buf_zone; 357 358/* 359 * Single global constant for BUF_WMESG, to avoid getting multiple references. 360 * buf_wmesg is referred from macros. 361 */ 362const char *buf_wmesg = BUF_WMESG; 363 364static int 365sysctl_runningspace(SYSCTL_HANDLER_ARGS) 366{ 367 long value; 368 int error; 369 370 value = *(long *)arg1; 371 error = sysctl_handle_long(oidp, &value, 0, req); 372 if (error != 0 || req->newptr == NULL) 373 return (error); 374 mtx_lock(&rbreqlock); 375 if (arg1 == &hirunningspace) { 376 if (value < lorunningspace) 377 error = EINVAL; 378 else 379 hirunningspace = value; 380 } else { 381 KASSERT(arg1 == &lorunningspace, 382 ("%s: unknown arg1", __func__)); 383 if (value > hirunningspace) 384 error = EINVAL; 385 else 386 lorunningspace = value; 387 } 388 mtx_unlock(&rbreqlock); 389 return (error); 390} 391 392#if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 393 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 394static int 395sysctl_bufspace(SYSCTL_HANDLER_ARGS) 396{ 397 long lvalue; 398 int ivalue; 399 400 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long)) 401 return (sysctl_handle_long(oidp, arg1, arg2, req)); 402 lvalue = *(long *)arg1; 403 if (lvalue > INT_MAX) 404 /* On overflow, still write out a long to trigger ENOMEM. */ 405 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 406 ivalue = lvalue; 407 return (sysctl_handle_int(oidp, &ivalue, 0, req)); 408} 409#endif 410 411static int 412bqcleanq(void) 413{ 414 static int nextq; 415 416 return ((atomic_fetchadd_int(&nextq, 1) % clean_queues) + QUEUE_CLEAN); 417} 418 419static int 420bqisclean(int qindex) 421{ 422 423 return (qindex >= QUEUE_CLEAN && qindex < QUEUE_CLEAN + CLEAN_QUEUES); 424} 425 426/* 427 * bqlock: 428 * 429 * Return the appropriate queue lock based on the index. 430 */ 431static inline struct mtx * 432bqlock(int qindex) 433{ 434 435 return (struct mtx *)&bqlocks[qindex]; 436} 437 438/* 439 * bdirtywakeup: 440 * 441 * Wakeup any bwillwrite() waiters. 442 */ 443static void 444bdirtywakeup(void) 445{ 446 mtx_lock(&bdirtylock); 447 if (bdirtywait) { 448 bdirtywait = 0; 449 wakeup(&bdirtywait); 450 } 451 mtx_unlock(&bdirtylock); 452} 453 454/* 455 * bdirtysub: 456 * 457 * Decrement the numdirtybuffers count by one and wakeup any 458 * threads blocked in bwillwrite(). 459 */ 460static void 461bdirtysub(void) 462{ 463 464 if (atomic_fetchadd_int(&numdirtybuffers, -1) == 465 (lodirtybuffers + hidirtybuffers) / 2) 466 bdirtywakeup(); 467} 468 469/* 470 * bdirtyadd: 471 * 472 * Increment the numdirtybuffers count by one and wakeup the buf 473 * daemon if needed. 474 */ 475static void 476bdirtyadd(void) 477{ 478 479 /* 480 * Only do the wakeup once as we cross the boundary. The 481 * buf daemon will keep running until the condition clears. 482 */ 483 if (atomic_fetchadd_int(&numdirtybuffers, 1) == 484 (lodirtybuffers + hidirtybuffers) / 2) 485 bd_wakeup(); 486} 487 488/* 489 * bufspace_wakeup: 490 * 491 * Called when buffer space is potentially available for recovery. 492 * getnewbuf() will block on this flag when it is unable to free 493 * sufficient buffer space. Buffer space becomes recoverable when 494 * bp's get placed back in the queues. 495 */ 496static void 497bufspace_wakeup(void) 498{ 499 500 /* 501 * If someone is waiting for bufspace, wake them up. 502 * 503 * Since needsbuffer is set prior to doing an additional queue 504 * scan it is safe to check for the flag prior to acquiring the 505 * lock. The thread that is preparing to scan again before 506 * blocking would discover the buf we released. 507 */ 508 if (needsbuffer) { 509 rw_rlock(&nblock); 510 if (atomic_cmpset_int(&needsbuffer, 1, 0) == 1) 511 wakeup(__DEVOLATILE(void *, &needsbuffer)); 512 rw_runlock(&nblock); 513 } 514} 515 516/* 517 * bufspace_daemonwakeup: 518 * 519 * Wakeup the daemon responsible for freeing clean bufs. 520 */ 521static void 522bufspace_daemonwakeup(void) 523{ 524 rw_rlock(&nblock); 525 if (bufspace_request == 0) { 526 bufspace_request = 1; 527 wakeup(&bufspace_request); 528 } 529 rw_runlock(&nblock); 530} 531 532/* 533 * bufspace_adjust: 534 * 535 * Adjust the reported bufspace for a KVA managed buffer, possibly 536 * waking any waiters. 537 */ 538static void 539bufspace_adjust(struct buf *bp, int bufsize) 540{ 541 long space; 542 int diff; 543 544 KASSERT((bp->b_flags & B_MALLOC) == 0, 545 ("bufspace_adjust: malloc buf %p", bp)); 546 diff = bufsize - bp->b_bufsize; 547 if (diff < 0) { 548 atomic_subtract_long(&bufspace, -diff); 549 bufspace_wakeup(); 550 } else { 551 space = atomic_fetchadd_long(&bufspace, diff); 552 /* Wake up the daemon on the transition. */ 553 if (space < bufspacethresh && space + diff >= bufspacethresh) 554 bufspace_daemonwakeup(); 555 } 556 bp->b_bufsize = bufsize; 557} 558 559/* 560 * bufspace_reserve: 561 * 562 * Reserve bufspace before calling allocbuf(). metadata has a 563 * different space limit than data. 564 */ 565static int 566bufspace_reserve(int size, bool metadata) 567{ 568 long limit; 569 long space; 570 571 if (metadata) 572 limit = maxbufspace; 573 else 574 limit = hibufspace; 575 do { 576 space = bufspace; 577 if (space + size > limit) 578 return (ENOSPC); 579 } while (atomic_cmpset_long(&bufspace, space, space + size) == 0); 580 581 /* Wake up the daemon on the transition. */ 582 if (space < bufspacethresh && space + size >= bufspacethresh) 583 bufspace_daemonwakeup(); 584 585 return (0); 586} 587 588/* 589 * bufspace_release: 590 * 591 * Release reserved bufspace after bufspace_adjust() has consumed it. 592 */ 593static void 594bufspace_release(int size) 595{ 596 atomic_subtract_long(&bufspace, size); 597 bufspace_wakeup(); 598} 599 600/* 601 * bufspace_wait: 602 * 603 * Wait for bufspace, acting as the buf daemon if a locked vnode is 604 * supplied. needsbuffer must be set in a safe fashion prior to 605 * polling for space. The operation must be re-tried on return. 606 */ 607static void 608bufspace_wait(struct vnode *vp, int gbflags, int slpflag, int slptimeo) 609{ 610 struct thread *td; 611 int error, fl, norunbuf; 612 613 if ((gbflags & GB_NOWAIT_BD) != 0) 614 return; 615 616 td = curthread; 617 rw_wlock(&nblock); 618 while (needsbuffer != 0) { 619 if (vp != NULL && vp->v_type != VCHR && 620 (td->td_pflags & TDP_BUFNEED) == 0) { 621 rw_wunlock(&nblock); 622 /* 623 * getblk() is called with a vnode locked, and 624 * some majority of the dirty buffers may as 625 * well belong to the vnode. Flushing the 626 * buffers there would make a progress that 627 * cannot be achieved by the buf_daemon, that 628 * cannot lock the vnode. 629 */ 630 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) | 631 (td->td_pflags & TDP_NORUNNINGBUF); 632 633 /* 634 * Play bufdaemon. The getnewbuf() function 635 * may be called while the thread owns lock 636 * for another dirty buffer for the same 637 * vnode, which makes it impossible to use 638 * VOP_FSYNC() there, due to the buffer lock 639 * recursion. 640 */ 641 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF; 642 fl = buf_flush(vp, flushbufqtarget); 643 td->td_pflags &= norunbuf; 644 rw_wlock(&nblock); 645 if (fl != 0) 646 continue; 647 if (needsbuffer == 0) 648 break; 649 } 650 error = rw_sleep(__DEVOLATILE(void *, &needsbuffer), &nblock, 651 (PRIBIO + 4) | slpflag, "newbuf", slptimeo); 652 if (error != 0) 653 break; 654 } 655 rw_wunlock(&nblock); 656} 657 658 659/* 660 * bufspace_daemon: 661 * 662 * buffer space management daemon. Tries to maintain some marginal 663 * amount of free buffer space so that requesting processes neither 664 * block nor work to reclaim buffers. 665 */ 666static void 667bufspace_daemon(void) 668{ 669 for (;;) { 670 kproc_suspend_check(bufspacedaemonproc); 671 672 /* 673 * Free buffers from the clean queue until we meet our 674 * targets. 675 * 676 * Theory of operation: The buffer cache is most efficient 677 * when some free buffer headers and space are always 678 * available to getnewbuf(). This daemon attempts to prevent 679 * the excessive blocking and synchronization associated 680 * with shortfall. It goes through three phases according 681 * demand: 682 * 683 * 1) The daemon wakes up voluntarily once per-second 684 * during idle periods when the counters are below 685 * the wakeup thresholds (bufspacethresh, lofreebuffers). 686 * 687 * 2) The daemon wakes up as we cross the thresholds 688 * ahead of any potential blocking. This may bounce 689 * slightly according to the rate of consumption and 690 * release. 691 * 692 * 3) The daemon and consumers are starved for working 693 * clean buffers. This is the 'bufspace' sleep below 694 * which will inefficiently trade bufs with bqrelse 695 * until we return to condition 2. 696 */ 697 while (bufspace > lobufspace || 698 numfreebuffers < hifreebuffers) { 699 if (buf_recycle(false) != 0) { 700 atomic_set_int(&needsbuffer, 1); 701 if (buf_recycle(false) != 0) { 702 rw_wlock(&nblock); 703 if (needsbuffer) 704 rw_sleep(__DEVOLATILE(void *, 705 &needsbuffer), &nblock, 706 PRIBIO|PDROP, "bufspace", 707 hz/10); 708 else 709 rw_wunlock(&nblock); 710 } 711 } 712 maybe_yield(); 713 } 714 715 /* 716 * Re-check our limits under the exclusive nblock. 717 */ 718 rw_wlock(&nblock); 719 if (bufspace < bufspacethresh && 720 numfreebuffers > lofreebuffers) { 721 bufspace_request = 0; 722 rw_sleep(&bufspace_request, &nblock, PRIBIO|PDROP, 723 "-", hz); 724 } else 725 rw_wunlock(&nblock); 726 } 727} 728 729static struct kproc_desc bufspace_kp = { 730 "bufspacedaemon", 731 bufspace_daemon, 732 &bufspacedaemonproc 733}; 734SYSINIT(bufspacedaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, 735 &bufspace_kp); 736 737/* 738 * bufmallocadjust: 739 * 740 * Adjust the reported bufspace for a malloc managed buffer, possibly 741 * waking any waiters. 742 */ 743static void 744bufmallocadjust(struct buf *bp, int bufsize) 745{ 746 int diff; 747 748 KASSERT((bp->b_flags & B_MALLOC) != 0, 749 ("bufmallocadjust: non-malloc buf %p", bp)); 750 diff = bufsize - bp->b_bufsize; 751 if (diff < 0) 752 atomic_subtract_long(&bufmallocspace, -diff); 753 else 754 atomic_add_long(&bufmallocspace, diff); 755 bp->b_bufsize = bufsize; 756} 757 758/* 759 * runningwakeup: 760 * 761 * Wake up processes that are waiting on asynchronous writes to fall 762 * below lorunningspace. 763 */ 764static void 765runningwakeup(void) 766{ 767 768 mtx_lock(&rbreqlock); 769 if (runningbufreq) { 770 runningbufreq = 0; 771 wakeup(&runningbufreq); 772 } 773 mtx_unlock(&rbreqlock); 774} 775 776/* 777 * runningbufwakeup: 778 * 779 * Decrement the outstanding write count according. 780 */ 781void 782runningbufwakeup(struct buf *bp) 783{ 784 long space, bspace; 785 786 bspace = bp->b_runningbufspace; 787 if (bspace == 0) 788 return; 789 space = atomic_fetchadd_long(&runningbufspace, -bspace); 790 KASSERT(space >= bspace, ("runningbufspace underflow %ld %ld", 791 space, bspace)); 792 bp->b_runningbufspace = 0; 793 /* 794 * Only acquire the lock and wakeup on the transition from exceeding 795 * the threshold to falling below it. 796 */ 797 if (space < lorunningspace) 798 return; 799 if (space - bspace > lorunningspace) 800 return; 801 runningwakeup(); 802} 803 804/* 805 * waitrunningbufspace() 806 * 807 * runningbufspace is a measure of the amount of I/O currently 808 * running. This routine is used in async-write situations to 809 * prevent creating huge backups of pending writes to a device. 810 * Only asynchronous writes are governed by this function. 811 * 812 * This does NOT turn an async write into a sync write. It waits 813 * for earlier writes to complete and generally returns before the 814 * caller's write has reached the device. 815 */ 816void 817waitrunningbufspace(void) 818{ 819 820 mtx_lock(&rbreqlock); 821 while (runningbufspace > hirunningspace) { 822 runningbufreq = 1; 823 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 824 } 825 mtx_unlock(&rbreqlock); 826} 827 828 829/* 830 * vfs_buf_test_cache: 831 * 832 * Called when a buffer is extended. This function clears the B_CACHE 833 * bit if the newly extended portion of the buffer does not contain 834 * valid data. 835 */ 836static __inline void 837vfs_buf_test_cache(struct buf *bp, vm_ooffset_t foff, vm_offset_t off, 838 vm_offset_t size, vm_page_t m) 839{ 840 841 VM_OBJECT_ASSERT_LOCKED(m->object); 842 if (bp->b_flags & B_CACHE) { 843 int base = (foff + off) & PAGE_MASK; 844 if (vm_page_is_valid(m, base, size) == 0) 845 bp->b_flags &= ~B_CACHE; 846 } 847} 848 849/* Wake up the buffer daemon if necessary */ 850static __inline void 851bd_wakeup(void) 852{ 853 854 mtx_lock(&bdlock); 855 if (bd_request == 0) { 856 bd_request = 1; 857 wakeup(&bd_request); 858 } 859 mtx_unlock(&bdlock); 860} 861 862/* 863 * Adjust the maxbcachbuf tunable. 864 */ 865static void 866maxbcachebuf_adjust(void) 867{ 868 int i; 869 870 /* 871 * maxbcachebuf must be a power of 2 >= MAXBSIZE. 872 */ 873 i = 2; 874 while (i * 2 <= maxbcachebuf) 875 i *= 2; 876 maxbcachebuf = i; 877 if (maxbcachebuf < MAXBSIZE) 878 maxbcachebuf = MAXBSIZE; 879 if (maxbcachebuf > MAXPHYS) 880 maxbcachebuf = MAXPHYS; 881 if (bootverbose != 0 && maxbcachebuf != MAXBCACHEBUF) 882 printf("maxbcachebuf=%d\n", maxbcachebuf); 883} 884 885/* 886 * bd_speedup - speedup the buffer cache flushing code 887 */ 888void 889bd_speedup(void) 890{ 891 int needwake; 892 893 mtx_lock(&bdlock); 894 needwake = 0; 895 if (bd_speedupreq == 0 || bd_request == 0) 896 needwake = 1; 897 bd_speedupreq = 1; 898 bd_request = 1; 899 if (needwake) 900 wakeup(&bd_request); 901 mtx_unlock(&bdlock); 902} 903 904#ifndef NSWBUF_MIN 905#define NSWBUF_MIN 16 906#endif 907 908#ifdef __i386__ 909#define TRANSIENT_DENOM 5 910#else 911#define TRANSIENT_DENOM 10 912#endif 913 914/* 915 * Calculating buffer cache scaling values and reserve space for buffer 916 * headers. This is called during low level kernel initialization and 917 * may be called more then once. We CANNOT write to the memory area 918 * being reserved at this time. 919 */ 920caddr_t 921kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 922{ 923 int tuned_nbuf; 924 long maxbuf, maxbuf_sz, buf_sz, biotmap_sz; 925 926 /* 927 * physmem_est is in pages. Convert it to kilobytes (assumes 928 * PAGE_SIZE is >= 1K) 929 */ 930 physmem_est = physmem_est * (PAGE_SIZE / 1024); 931 932 maxbcachebuf_adjust(); 933 /* 934 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 935 * For the first 64MB of ram nominally allocate sufficient buffers to 936 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 937 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing 938 * the buffer cache we limit the eventual kva reservation to 939 * maxbcache bytes. 940 * 941 * factor represents the 1/4 x ram conversion. 942 */ 943 if (nbuf == 0) { 944 int factor = 4 * BKVASIZE / 1024; 945 946 nbuf = 50; 947 if (physmem_est > 4096) 948 nbuf += min((physmem_est - 4096) / factor, 949 65536 / factor); 950 if (physmem_est > 65536) 951 nbuf += min((physmem_est - 65536) * 2 / (factor * 5), 952 32 * 1024 * 1024 / (factor * 5)); 953 954 if (maxbcache && nbuf > maxbcache / BKVASIZE) 955 nbuf = maxbcache / BKVASIZE; 956 tuned_nbuf = 1; 957 } else 958 tuned_nbuf = 0; 959 960 /* XXX Avoid unsigned long overflows later on with maxbufspace. */ 961 maxbuf = (LONG_MAX / 3) / BKVASIZE; 962 if (nbuf > maxbuf) { 963 if (!tuned_nbuf) 964 printf("Warning: nbufs lowered from %d to %ld\n", nbuf, 965 maxbuf); 966 nbuf = maxbuf; 967 } 968 969 /* 970 * Ideal allocation size for the transient bio submap is 10% 971 * of the maximal space buffer map. This roughly corresponds 972 * to the amount of the buffer mapped for typical UFS load. 973 * 974 * Clip the buffer map to reserve space for the transient 975 * BIOs, if its extent is bigger than 90% (80% on i386) of the 976 * maximum buffer map extent on the platform. 977 * 978 * The fall-back to the maxbuf in case of maxbcache unset, 979 * allows to not trim the buffer KVA for the architectures 980 * with ample KVA space. 981 */ 982 if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) { 983 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE; 984 buf_sz = (long)nbuf * BKVASIZE; 985 if (buf_sz < maxbuf_sz / TRANSIENT_DENOM * 986 (TRANSIENT_DENOM - 1)) { 987 /* 988 * There is more KVA than memory. Do not 989 * adjust buffer map size, and assign the rest 990 * of maxbuf to transient map. 991 */ 992 biotmap_sz = maxbuf_sz - buf_sz; 993 } else { 994 /* 995 * Buffer map spans all KVA we could afford on 996 * this platform. Give 10% (20% on i386) of 997 * the buffer map to the transient bio map. 998 */ 999 biotmap_sz = buf_sz / TRANSIENT_DENOM; 1000 buf_sz -= biotmap_sz; 1001 } 1002 if (biotmap_sz / INT_MAX > MAXPHYS) 1003 bio_transient_maxcnt = INT_MAX; 1004 else 1005 bio_transient_maxcnt = biotmap_sz / MAXPHYS; 1006 /* 1007 * Artificially limit to 1024 simultaneous in-flight I/Os 1008 * using the transient mapping. 1009 */ 1010 if (bio_transient_maxcnt > 1024) 1011 bio_transient_maxcnt = 1024; 1012 if (tuned_nbuf) 1013 nbuf = buf_sz / BKVASIZE; 1014 } 1015 1016 /* 1017 * swbufs are used as temporary holders for I/O, such as paging I/O. 1018 * We have no less then 16 and no more then 256. 1019 */ 1020 nswbuf = min(nbuf / 4, 256); 1021 TUNABLE_INT_FETCH("kern.nswbuf", &nswbuf); 1022 if (nswbuf < NSWBUF_MIN) 1023 nswbuf = NSWBUF_MIN; 1024 1025 /* 1026 * Reserve space for the buffer cache buffers 1027 */ 1028 swbuf = (void *)v; 1029 v = (caddr_t)(swbuf + nswbuf); 1030 buf = (void *)v; 1031 v = (caddr_t)(buf + nbuf); 1032 1033 return(v); 1034} 1035 1036/* Initialize the buffer subsystem. Called before use of any buffers. */ 1037void 1038bufinit(void) 1039{ 1040 struct buf *bp; 1041 int i; 1042 1043 KASSERT(maxbcachebuf >= MAXBSIZE, 1044 ("maxbcachebuf (%d) must be >= MAXBSIZE (%d)\n", maxbcachebuf, 1045 MAXBSIZE)); 1046 mtx_init(&bqlocks[QUEUE_DIRTY], "bufq dirty lock", NULL, MTX_DEF); 1047 mtx_init(&bqlocks[QUEUE_EMPTY], "bufq empty lock", NULL, MTX_DEF); 1048 for (i = QUEUE_CLEAN; i < QUEUE_CLEAN + CLEAN_QUEUES; i++) 1049 mtx_init(&bqlocks[i], "bufq clean lock", NULL, MTX_DEF); 1050 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 1051 rw_init(&nblock, "needsbuffer lock"); 1052 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 1053 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF); 1054 1055 /* next, make a null set of free lists */ 1056 for (i = 0; i < BUFFER_QUEUES; i++) 1057 TAILQ_INIT(&bufqueues[i]); 1058 1059 unmapped_buf = (caddr_t)kva_alloc(MAXPHYS); 1060 1061 /* finally, initialize each buffer header and stick on empty q */ 1062 for (i = 0; i < nbuf; i++) { 1063 bp = &buf[i]; 1064 bzero(bp, sizeof *bp); 1065 bp->b_flags = B_INVAL; 1066 bp->b_rcred = NOCRED; 1067 bp->b_wcred = NOCRED; 1068 bp->b_qindex = QUEUE_EMPTY; 1069 bp->b_xflags = 0; 1070 bp->b_data = bp->b_kvabase = unmapped_buf; 1071 LIST_INIT(&bp->b_dep); 1072 BUF_LOCKINIT(bp); 1073 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 1074#ifdef INVARIANTS 1075 bq_len[QUEUE_EMPTY]++; 1076#endif 1077 } 1078 1079 /* 1080 * maxbufspace is the absolute maximum amount of buffer space we are 1081 * allowed to reserve in KVM and in real terms. The absolute maximum 1082 * is nominally used by metadata. hibufspace is the nominal maximum 1083 * used by most other requests. The differential is required to 1084 * ensure that metadata deadlocks don't occur. 1085 * 1086 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 1087 * this may result in KVM fragmentation which is not handled optimally 1088 * by the system. XXX This is less true with vmem. We could use 1089 * PAGE_SIZE. 1090 */ 1091 maxbufspace = (long)nbuf * BKVASIZE; 1092 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - maxbcachebuf * 10); 1093 lobufspace = (hibufspace / 20) * 19; /* 95% */ 1094 bufspacethresh = lobufspace + (hibufspace - lobufspace) / 2; 1095 1096 /* 1097 * Note: The 16 MiB upper limit for hirunningspace was chosen 1098 * arbitrarily and may need further tuning. It corresponds to 1099 * 128 outstanding write IO requests (if IO size is 128 KiB), 1100 * which fits with many RAID controllers' tagged queuing limits. 1101 * The lower 1 MiB limit is the historical upper limit for 1102 * hirunningspace. 1103 */ 1104 hirunningspace = lmax(lmin(roundup(hibufspace / 64, maxbcachebuf), 1105 16 * 1024 * 1024), 1024 * 1024); 1106 lorunningspace = roundup((hirunningspace * 2) / 3, maxbcachebuf); 1107 1108 /* 1109 * Limit the amount of malloc memory since it is wired permanently into 1110 * the kernel space. Even though this is accounted for in the buffer 1111 * allocation, we don't want the malloced region to grow uncontrolled. 1112 * The malloc scheme improves memory utilization significantly on 1113 * average (small) directories. 1114 */ 1115 maxbufmallocspace = hibufspace / 20; 1116 1117 /* 1118 * Reduce the chance of a deadlock occurring by limiting the number 1119 * of delayed-write dirty buffers we allow to stack up. 1120 */ 1121 hidirtybuffers = nbuf / 4 + 20; 1122 dirtybufthresh = hidirtybuffers * 9 / 10; 1123 numdirtybuffers = 0; 1124 /* 1125 * To support extreme low-memory systems, make sure hidirtybuffers 1126 * cannot eat up all available buffer space. This occurs when our 1127 * minimum cannot be met. We try to size hidirtybuffers to 3/4 our 1128 * buffer space assuming BKVASIZE'd buffers. 1129 */ 1130 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 1131 hidirtybuffers >>= 1; 1132 } 1133 lodirtybuffers = hidirtybuffers / 2; 1134 1135 /* 1136 * lofreebuffers should be sufficient to avoid stalling waiting on 1137 * buf headers under heavy utilization. The bufs in per-cpu caches 1138 * are counted as free but will be unavailable to threads executing 1139 * on other cpus. 1140 * 1141 * hifreebuffers is the free target for the bufspace daemon. This 1142 * should be set appropriately to limit work per-iteration. 1143 */ 1144 lofreebuffers = MIN((nbuf / 25) + (20 * mp_ncpus), 128 * mp_ncpus); 1145 hifreebuffers = (3 * lofreebuffers) / 2; 1146 numfreebuffers = nbuf; 1147 1148 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ | 1149 VM_ALLOC_NORMAL | VM_ALLOC_WIRED); 1150 1151 /* Setup the kva and free list allocators. */ 1152 vmem_set_reclaim(buffer_arena, bufkva_reclaim); 1153 buf_zone = uma_zcache_create("buf free cache", sizeof(struct buf), 1154 NULL, NULL, NULL, NULL, buf_import, buf_release, NULL, 0); 1155 1156 /* 1157 * Size the clean queue according to the amount of buffer space. 1158 * One queue per-256mb up to the max. More queues gives better 1159 * concurrency but less accurate LRU. 1160 */ 1161 clean_queues = MIN(howmany(maxbufspace, 256*1024*1024), CLEAN_QUEUES); 1162 1163} 1164 1165#ifdef INVARIANTS 1166static inline void 1167vfs_buf_check_mapped(struct buf *bp) 1168{ 1169 1170 KASSERT(bp->b_kvabase != unmapped_buf, 1171 ("mapped buf: b_kvabase was not updated %p", bp)); 1172 KASSERT(bp->b_data != unmapped_buf, 1173 ("mapped buf: b_data was not updated %p", bp)); 1174 KASSERT(bp->b_data < unmapped_buf || bp->b_data >= unmapped_buf + 1175 MAXPHYS, ("b_data + b_offset unmapped %p", bp)); 1176} 1177 1178static inline void 1179vfs_buf_check_unmapped(struct buf *bp) 1180{ 1181 1182 KASSERT(bp->b_data == unmapped_buf, 1183 ("unmapped buf: corrupted b_data %p", bp)); 1184} 1185 1186#define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp) 1187#define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp) 1188#else 1189#define BUF_CHECK_MAPPED(bp) do {} while (0) 1190#define BUF_CHECK_UNMAPPED(bp) do {} while (0) 1191#endif 1192 1193static int 1194isbufbusy(struct buf *bp) 1195{ 1196 if (((bp->b_flags & B_INVAL) == 0 && BUF_ISLOCKED(bp)) || 1197 ((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI)) 1198 return (1); 1199 return (0); 1200} 1201 1202/* 1203 * Shutdown the system cleanly to prepare for reboot, halt, or power off. 1204 */ 1205void 1206bufshutdown(int show_busybufs) 1207{ 1208 static int first_buf_printf = 1; 1209 struct buf *bp; 1210 int iter, nbusy, pbusy; 1211#ifndef PREEMPTION 1212 int subiter; 1213#endif 1214 1215 /* 1216 * Sync filesystems for shutdown 1217 */ 1218 wdog_kern_pat(WD_LASTVAL); 1219 sys_sync(curthread, NULL); 1220 1221 /* 1222 * With soft updates, some buffers that are 1223 * written will be remarked as dirty until other 1224 * buffers are written. 1225 */ 1226 for (iter = pbusy = 0; iter < 20; iter++) { 1227 nbusy = 0; 1228 for (bp = &buf[nbuf]; --bp >= buf; ) 1229 if (isbufbusy(bp)) 1230 nbusy++; 1231 if (nbusy == 0) { 1232 if (first_buf_printf) 1233 printf("All buffers synced."); 1234 break; 1235 } 1236 if (first_buf_printf) { 1237 printf("Syncing disks, buffers remaining... "); 1238 first_buf_printf = 0; 1239 } 1240 printf("%d ", nbusy); 1241 if (nbusy < pbusy) 1242 iter = 0; 1243 pbusy = nbusy; 1244 1245 wdog_kern_pat(WD_LASTVAL); 1246 sys_sync(curthread, NULL); 1247 1248#ifdef PREEMPTION 1249 /* 1250 * Drop Giant and spin for a while to allow 1251 * interrupt threads to run. 1252 */ 1253 DROP_GIANT(); 1254 DELAY(50000 * iter); 1255 PICKUP_GIANT(); 1256#else 1257 /* 1258 * Drop Giant and context switch several times to 1259 * allow interrupt threads to run. 1260 */ 1261 DROP_GIANT(); 1262 for (subiter = 0; subiter < 50 * iter; subiter++) { 1263 thread_lock(curthread); 1264 mi_switch(SW_VOL, NULL); 1265 thread_unlock(curthread); 1266 DELAY(1000); 1267 } 1268 PICKUP_GIANT(); 1269#endif 1270 } 1271 printf("\n"); 1272 /* 1273 * Count only busy local buffers to prevent forcing 1274 * a fsck if we're just a client of a wedged NFS server 1275 */ 1276 nbusy = 0; 1277 for (bp = &buf[nbuf]; --bp >= buf; ) { 1278 if (isbufbusy(bp)) { 1279#if 0 1280/* XXX: This is bogus. We should probably have a BO_REMOTE flag instead */ 1281 if (bp->b_dev == NULL) { 1282 TAILQ_REMOVE(&mountlist, 1283 bp->b_vp->v_mount, mnt_list); 1284 continue; 1285 } 1286#endif 1287 nbusy++; 1288 if (show_busybufs > 0) { 1289 printf( 1290 "%d: buf:%p, vnode:%p, flags:%0x, blkno:%jd, lblkno:%jd, buflock:", 1291 nbusy, bp, bp->b_vp, bp->b_flags, 1292 (intmax_t)bp->b_blkno, 1293 (intmax_t)bp->b_lblkno); 1294 BUF_LOCKPRINTINFO(bp); 1295 if (show_busybufs > 1) 1296 vn_printf(bp->b_vp, 1297 "vnode content: "); 1298 } 1299 } 1300 } 1301 if (nbusy) { 1302 /* 1303 * Failed to sync all blocks. Indicate this and don't 1304 * unmount filesystems (thus forcing an fsck on reboot). 1305 */ 1306 printf("Giving up on %d buffers\n", nbusy); 1307 DELAY(5000000); /* 5 seconds */ 1308 } else { 1309 if (!first_buf_printf) 1310 printf("Final sync complete\n"); 1311 /* 1312 * Unmount filesystems 1313 */ 1314 if (panicstr == NULL) 1315 vfs_unmountall(); 1316 } 1317 swapoff_all(); 1318 DELAY(100000); /* wait for console output to finish */ 1319} 1320 1321static void 1322bpmap_qenter(struct buf *bp) 1323{ 1324 1325 BUF_CHECK_MAPPED(bp); 1326 1327 /* 1328 * bp->b_data is relative to bp->b_offset, but 1329 * bp->b_offset may be offset into the first page. 1330 */ 1331 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data); 1332 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages); 1333 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 1334 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 1335} 1336 1337/* 1338 * binsfree: 1339 * 1340 * Insert the buffer into the appropriate free list. 1341 */ 1342static void 1343binsfree(struct buf *bp, int qindex) 1344{ 1345 struct mtx *olock, *nlock; 1346 1347 if (qindex != QUEUE_EMPTY) { 1348 BUF_ASSERT_XLOCKED(bp); 1349 } 1350 1351 /* 1352 * Stick to the same clean queue for the lifetime of the buf to 1353 * limit locking below. Otherwise pick ont sequentially. 1354 */ 1355 if (qindex == QUEUE_CLEAN) { 1356 if (bqisclean(bp->b_qindex)) 1357 qindex = bp->b_qindex; 1358 else 1359 qindex = bqcleanq(); 1360 } 1361 1362 /* 1363 * Handle delayed bremfree() processing. 1364 */ 1365 nlock = bqlock(qindex); 1366 if (bp->b_flags & B_REMFREE) { 1367 olock = bqlock(bp->b_qindex); 1368 mtx_lock(olock); 1369 bremfreel(bp); 1370 if (olock != nlock) { 1371 mtx_unlock(olock); 1372 mtx_lock(nlock); 1373 } 1374 } else 1375 mtx_lock(nlock); 1376 1377 if (bp->b_qindex != QUEUE_NONE) 1378 panic("binsfree: free buffer onto another queue???"); 1379 1380 bp->b_qindex = qindex; 1381 if (bp->b_flags & B_AGE) 1382 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1383 else 1384 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1385#ifdef INVARIANTS 1386 bq_len[bp->b_qindex]++; 1387#endif 1388 mtx_unlock(nlock); 1389} 1390 1391/* 1392 * buf_free: 1393 * 1394 * Free a buffer to the buf zone once it no longer has valid contents. 1395 */ 1396static void 1397buf_free(struct buf *bp) 1398{ 1399 1400 if (bp->b_flags & B_REMFREE) 1401 bremfreef(bp); 1402 if (bp->b_vflags & BV_BKGRDINPROG) 1403 panic("losing buffer 1"); 1404 if (bp->b_rcred != NOCRED) { 1405 crfree(bp->b_rcred); 1406 bp->b_rcred = NOCRED; 1407 } 1408 if (bp->b_wcred != NOCRED) { 1409 crfree(bp->b_wcred); 1410 bp->b_wcred = NOCRED; 1411 } 1412 if (!LIST_EMPTY(&bp->b_dep)) 1413 buf_deallocate(bp); 1414 bufkva_free(bp); 1415 BUF_UNLOCK(bp); 1416 uma_zfree(buf_zone, bp); 1417 atomic_add_int(&numfreebuffers, 1); 1418 bufspace_wakeup(); 1419} 1420 1421/* 1422 * buf_import: 1423 * 1424 * Import bufs into the uma cache from the buf list. The system still 1425 * expects a static array of bufs and much of the synchronization 1426 * around bufs assumes type stable storage. As a result, UMA is used 1427 * only as a per-cpu cache of bufs still maintained on a global list. 1428 */ 1429static int 1430buf_import(void *arg, void **store, int cnt, int flags) 1431{ 1432 struct buf *bp; 1433 int i; 1434 1435 mtx_lock(&bqlocks[QUEUE_EMPTY]); 1436 for (i = 0; i < cnt; i++) { 1437 bp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1438 if (bp == NULL) 1439 break; 1440 bremfreel(bp); 1441 store[i] = bp; 1442 } 1443 mtx_unlock(&bqlocks[QUEUE_EMPTY]); 1444 1445 return (i); 1446} 1447 1448/* 1449 * buf_release: 1450 * 1451 * Release bufs from the uma cache back to the buffer queues. 1452 */ 1453static void 1454buf_release(void *arg, void **store, int cnt) 1455{ 1456 int i; 1457 1458 for (i = 0; i < cnt; i++) 1459 binsfree(store[i], QUEUE_EMPTY); 1460} 1461 1462/* 1463 * buf_alloc: 1464 * 1465 * Allocate an empty buffer header. 1466 */ 1467static struct buf * 1468buf_alloc(void) 1469{ 1470 struct buf *bp; 1471 1472 bp = uma_zalloc(buf_zone, M_NOWAIT); 1473 if (bp == NULL) { 1474 bufspace_daemonwakeup(); 1475 atomic_add_int(&numbufallocfails, 1); 1476 return (NULL); 1477 } 1478 1479 /* 1480 * Wake-up the bufspace daemon on transition. 1481 */ 1482 if (atomic_fetchadd_int(&numfreebuffers, -1) == lofreebuffers) 1483 bufspace_daemonwakeup(); 1484 1485 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1486 panic("getnewbuf_empty: Locked buf %p on free queue.", bp); 1487 1488 KASSERT(bp->b_vp == NULL, 1489 ("bp: %p still has vnode %p.", bp, bp->b_vp)); 1490 KASSERT((bp->b_flags & (B_DELWRI | B_NOREUSE)) == 0, 1491 ("invalid buffer %p flags %#x", bp, bp->b_flags)); 1492 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 1493 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags)); 1494 KASSERT(bp->b_npages == 0, 1495 ("bp: %p still has %d vm pages\n", bp, bp->b_npages)); 1496 KASSERT(bp->b_kvasize == 0, ("bp: %p still has kva\n", bp)); 1497 KASSERT(bp->b_bufsize == 0, ("bp: %p still has bufspace\n", bp)); 1498 1499 bp->b_flags = 0; 1500 bp->b_ioflags = 0; 1501 bp->b_xflags = 0; 1502 bp->b_vflags = 0; 1503 bp->b_vp = NULL; 1504 bp->b_blkno = bp->b_lblkno = 0; 1505 bp->b_offset = NOOFFSET; 1506 bp->b_iodone = 0; 1507 bp->b_error = 0; 1508 bp->b_resid = 0; 1509 bp->b_bcount = 0; 1510 bp->b_npages = 0; 1511 bp->b_dirtyoff = bp->b_dirtyend = 0; 1512 bp->b_bufobj = NULL; 1513 bp->b_pin_count = 0; 1514 bp->b_data = bp->b_kvabase = unmapped_buf; 1515 bp->b_fsprivate1 = NULL; 1516 bp->b_fsprivate2 = NULL; 1517 bp->b_fsprivate3 = NULL; 1518 LIST_INIT(&bp->b_dep); 1519 1520 return (bp); 1521} 1522 1523/* 1524 * buf_qrecycle: 1525 * 1526 * Free a buffer from the given bufqueue. kva controls whether the 1527 * freed buf must own some kva resources. This is used for 1528 * defragmenting. 1529 */ 1530static int 1531buf_qrecycle(int qindex, bool kva) 1532{ 1533 struct buf *bp, *nbp; 1534 1535 if (kva) 1536 atomic_add_int(&bufdefragcnt, 1); 1537 nbp = NULL; 1538 mtx_lock(&bqlocks[qindex]); 1539 nbp = TAILQ_FIRST(&bufqueues[qindex]); 1540 1541 /* 1542 * Run scan, possibly freeing data and/or kva mappings on the fly 1543 * depending. 1544 */ 1545 while ((bp = nbp) != NULL) { 1546 /* 1547 * Calculate next bp (we can only use it if we do not 1548 * release the bqlock). 1549 */ 1550 nbp = TAILQ_NEXT(bp, b_freelist); 1551 1552 /* 1553 * If we are defragging then we need a buffer with 1554 * some kva to reclaim. 1555 */ 1556 if (kva && bp->b_kvasize == 0) 1557 continue; 1558 1559 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1560 continue; 1561 1562 /* 1563 * Skip buffers with background writes in progress. 1564 */ 1565 if ((bp->b_vflags & BV_BKGRDINPROG) != 0) { 1566 BUF_UNLOCK(bp); 1567 continue; 1568 } 1569 1570 KASSERT(bp->b_qindex == qindex, 1571 ("getnewbuf: inconsistent queue %d bp %p", qindex, bp)); 1572 /* 1573 * NOTE: nbp is now entirely invalid. We can only restart 1574 * the scan from this point on. 1575 */ 1576 bremfreel(bp); 1577 mtx_unlock(&bqlocks[qindex]); 1578 1579 /* 1580 * Requeue the background write buffer with error and 1581 * restart the scan. 1582 */ 1583 if ((bp->b_vflags & BV_BKGRDERR) != 0) { 1584 bqrelse(bp); 1585 mtx_lock(&bqlocks[qindex]); 1586 nbp = TAILQ_FIRST(&bufqueues[qindex]); 1587 continue; 1588 } 1589 bp->b_flags |= B_INVAL; 1590 brelse(bp); 1591 return (0); 1592 } 1593 mtx_unlock(&bqlocks[qindex]); 1594 1595 return (ENOBUFS); 1596} 1597 1598/* 1599 * buf_recycle: 1600 * 1601 * Iterate through all clean queues until we find a buf to recycle or 1602 * exhaust the search. 1603 */ 1604static int 1605buf_recycle(bool kva) 1606{ 1607 int qindex, first_qindex; 1608 1609 qindex = first_qindex = bqcleanq(); 1610 do { 1611 if (buf_qrecycle(qindex, kva) == 0) 1612 return (0); 1613 if (++qindex == QUEUE_CLEAN + clean_queues) 1614 qindex = QUEUE_CLEAN; 1615 } while (qindex != first_qindex); 1616 1617 return (ENOBUFS); 1618} 1619 1620/* 1621 * buf_scan: 1622 * 1623 * Scan the clean queues looking for a buffer to recycle. needsbuffer 1624 * is set on failure so that the caller may optionally bufspace_wait() 1625 * in a race-free fashion. 1626 */ 1627static int 1628buf_scan(bool defrag) 1629{ 1630 int error; 1631 1632 /* 1633 * To avoid heavy synchronization and wakeup races we set 1634 * needsbuffer and re-poll before failing. This ensures that 1635 * no frees can be missed between an unsuccessful poll and 1636 * going to sleep in a synchronized fashion. 1637 */ 1638 if ((error = buf_recycle(defrag)) != 0) { 1639 atomic_set_int(&needsbuffer, 1); 1640 bufspace_daemonwakeup(); 1641 error = buf_recycle(defrag); 1642 } 1643 if (error == 0) 1644 atomic_add_int(&getnewbufrestarts, 1); 1645 return (error); 1646} 1647 1648/* 1649 * bremfree: 1650 * 1651 * Mark the buffer for removal from the appropriate free list. 1652 * 1653 */ 1654void 1655bremfree(struct buf *bp) 1656{ 1657 1658 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1659 KASSERT((bp->b_flags & B_REMFREE) == 0, 1660 ("bremfree: buffer %p already marked for delayed removal.", bp)); 1661 KASSERT(bp->b_qindex != QUEUE_NONE, 1662 ("bremfree: buffer %p not on a queue.", bp)); 1663 BUF_ASSERT_XLOCKED(bp); 1664 1665 bp->b_flags |= B_REMFREE; 1666} 1667 1668/* 1669 * bremfreef: 1670 * 1671 * Force an immediate removal from a free list. Used only in nfs when 1672 * it abuses the b_freelist pointer. 1673 */ 1674void 1675bremfreef(struct buf *bp) 1676{ 1677 struct mtx *qlock; 1678 1679 qlock = bqlock(bp->b_qindex); 1680 mtx_lock(qlock); 1681 bremfreel(bp); 1682 mtx_unlock(qlock); 1683} 1684 1685/* 1686 * bremfreel: 1687 * 1688 * Removes a buffer from the free list, must be called with the 1689 * correct qlock held. 1690 */ 1691static void 1692bremfreel(struct buf *bp) 1693{ 1694 1695 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X", 1696 bp, bp->b_vp, bp->b_flags); 1697 KASSERT(bp->b_qindex != QUEUE_NONE, 1698 ("bremfreel: buffer %p not on a queue.", bp)); 1699 if (bp->b_qindex != QUEUE_EMPTY) { 1700 BUF_ASSERT_XLOCKED(bp); 1701 } 1702 mtx_assert(bqlock(bp->b_qindex), MA_OWNED); 1703 1704 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 1705#ifdef INVARIANTS 1706 KASSERT(bq_len[bp->b_qindex] >= 1, ("queue %d underflow", 1707 bp->b_qindex)); 1708 bq_len[bp->b_qindex]--; 1709#endif 1710 bp->b_qindex = QUEUE_NONE; 1711 bp->b_flags &= ~B_REMFREE; 1712} 1713 1714/* 1715 * bufkva_free: 1716 * 1717 * Free the kva allocation for a buffer. 1718 * 1719 */ 1720static void 1721bufkva_free(struct buf *bp) 1722{ 1723 1724#ifdef INVARIANTS 1725 if (bp->b_kvasize == 0) { 1726 KASSERT(bp->b_kvabase == unmapped_buf && 1727 bp->b_data == unmapped_buf, 1728 ("Leaked KVA space on %p", bp)); 1729 } else if (buf_mapped(bp)) 1730 BUF_CHECK_MAPPED(bp); 1731 else 1732 BUF_CHECK_UNMAPPED(bp); 1733#endif 1734 if (bp->b_kvasize == 0) 1735 return; 1736 1737 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, bp->b_kvasize); 1738 atomic_subtract_long(&bufkvaspace, bp->b_kvasize); 1739 atomic_add_int(&buffreekvacnt, 1); 1740 bp->b_data = bp->b_kvabase = unmapped_buf; 1741 bp->b_kvasize = 0; 1742} 1743 1744/* 1745 * bufkva_alloc: 1746 * 1747 * Allocate the buffer KVA and set b_kvasize and b_kvabase. 1748 */ 1749static int 1750bufkva_alloc(struct buf *bp, int maxsize, int gbflags) 1751{ 1752 vm_offset_t addr; 1753 int error; 1754 1755 KASSERT((gbflags & GB_UNMAPPED) == 0 || (gbflags & GB_KVAALLOC) != 0, 1756 ("Invalid gbflags 0x%x in %s", gbflags, __func__)); 1757 1758 bufkva_free(bp); 1759 1760 addr = 0; 1761 error = vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr); 1762 if (error != 0) { 1763 /* 1764 * Buffer map is too fragmented. Request the caller 1765 * to defragment the map. 1766 */ 1767 return (error); 1768 } 1769 bp->b_kvabase = (caddr_t)addr; 1770 bp->b_kvasize = maxsize; 1771 atomic_add_long(&bufkvaspace, bp->b_kvasize); 1772 if ((gbflags & GB_UNMAPPED) != 0) { 1773 bp->b_data = unmapped_buf; 1774 BUF_CHECK_UNMAPPED(bp); 1775 } else { 1776 bp->b_data = bp->b_kvabase; 1777 BUF_CHECK_MAPPED(bp); 1778 } 1779 return (0); 1780} 1781 1782/* 1783 * bufkva_reclaim: 1784 * 1785 * Reclaim buffer kva by freeing buffers holding kva. This is a vmem 1786 * callback that fires to avoid returning failure. 1787 */ 1788static void 1789bufkva_reclaim(vmem_t *vmem, int flags) 1790{ 1791 int i; 1792 1793 for (i = 0; i < 5; i++) 1794 if (buf_scan(true) != 0) 1795 break; 1796 return; 1797} 1798 1799 1800/* 1801 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 1802 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 1803 * the buffer is valid and we do not have to do anything. 1804 */ 1805void 1806breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, 1807 int cnt, struct ucred * cred) 1808{ 1809 struct buf *rabp; 1810 int i; 1811 1812 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 1813 if (inmem(vp, *rablkno)) 1814 continue; 1815 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 1816 1817 if ((rabp->b_flags & B_CACHE) == 0) { 1818 if (!TD_IS_IDLETHREAD(curthread)) { 1819#ifdef RACCT 1820 if (racct_enable) { 1821 PROC_LOCK(curproc); 1822 racct_add_buf(curproc, rabp, 0); 1823 PROC_UNLOCK(curproc); 1824 } 1825#endif /* RACCT */ 1826 curthread->td_ru.ru_inblock++; 1827 } 1828 rabp->b_flags |= B_ASYNC; 1829 rabp->b_flags &= ~B_INVAL; 1830 rabp->b_ioflags &= ~BIO_ERROR; 1831 rabp->b_iocmd = BIO_READ; 1832 if (rabp->b_rcred == NOCRED && cred != NOCRED) 1833 rabp->b_rcred = crhold(cred); 1834 vfs_busy_pages(rabp, 0); 1835 BUF_KERNPROC(rabp); 1836 rabp->b_iooffset = dbtob(rabp->b_blkno); 1837 bstrategy(rabp); 1838 } else { 1839 brelse(rabp); 1840 } 1841 } 1842} 1843 1844/* 1845 * Entry point for bread() and breadn() via #defines in sys/buf.h. 1846 * 1847 * Get a buffer with the specified data. Look in the cache first. We 1848 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 1849 * is set, the buffer is valid and we do not have to do anything, see 1850 * getblk(). Also starts asynchronous I/O on read-ahead blocks. 1851 * 1852 * Always return a NULL buffer pointer (in bpp) when returning an error. 1853 */ 1854int 1855breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno, 1856 int *rabsize, int cnt, struct ucred *cred, int flags, struct buf **bpp) 1857{ 1858 struct buf *bp; 1859 int rv = 0, readwait = 0; 1860 1861 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 1862 /* 1863 * Can only return NULL if GB_LOCK_NOWAIT flag is specified. 1864 */ 1865 *bpp = bp = getblk(vp, blkno, size, 0, 0, flags); 1866 if (bp == NULL) 1867 return (EBUSY); 1868 1869 /* if not found in cache, do some I/O */ 1870 if ((bp->b_flags & B_CACHE) == 0) { 1871 if (!TD_IS_IDLETHREAD(curthread)) { 1872#ifdef RACCT 1873 if (racct_enable) { 1874 PROC_LOCK(curproc); 1875 racct_add_buf(curproc, bp, 0); 1876 PROC_UNLOCK(curproc); 1877 } 1878#endif /* RACCT */ 1879 curthread->td_ru.ru_inblock++; 1880 } 1881 bp->b_iocmd = BIO_READ; 1882 bp->b_flags &= ~B_INVAL; 1883 bp->b_ioflags &= ~BIO_ERROR; 1884 if (bp->b_rcred == NOCRED && cred != NOCRED) 1885 bp->b_rcred = crhold(cred); 1886 vfs_busy_pages(bp, 0); 1887 bp->b_iooffset = dbtob(bp->b_blkno); 1888 bstrategy(bp); 1889 ++readwait; 1890 } 1891 1892 breada(vp, rablkno, rabsize, cnt, cred); 1893 1894 if (readwait) { 1895 rv = bufwait(bp); 1896 if (rv != 0) { 1897 brelse(bp); 1898 *bpp = NULL; 1899 } 1900 } 1901 return (rv); 1902} 1903 1904/* 1905 * Write, release buffer on completion. (Done by iodone 1906 * if async). Do not bother writing anything if the buffer 1907 * is invalid. 1908 * 1909 * Note that we set B_CACHE here, indicating that buffer is 1910 * fully valid and thus cacheable. This is true even of NFS 1911 * now so we set it generally. This could be set either here 1912 * or in biodone() since the I/O is synchronous. We put it 1913 * here. 1914 */ 1915int 1916bufwrite(struct buf *bp) 1917{ 1918 int oldflags; 1919 struct vnode *vp; 1920 long space; 1921 int vp_md; 1922 1923 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1924 if ((bp->b_bufobj->bo_flag & BO_DEAD) != 0) { 1925 bp->b_flags |= B_INVAL | B_RELBUF; 1926 bp->b_flags &= ~B_CACHE; 1927 brelse(bp); 1928 return (ENXIO); 1929 } 1930 if (bp->b_flags & B_INVAL) { 1931 brelse(bp); 1932 return (0); 1933 } 1934 1935 if (bp->b_flags & B_BARRIER) 1936 atomic_add_long(&barrierwrites, 1); 1937 1938 oldflags = bp->b_flags; 1939 1940 BUF_ASSERT_HELD(bp); 1941 1942 if (bp->b_pin_count > 0) 1943 bunpin_wait(bp); 1944 1945 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 1946 ("FFS background buffer should not get here %p", bp)); 1947 1948 vp = bp->b_vp; 1949 if (vp) 1950 vp_md = vp->v_vflag & VV_MD; 1951 else 1952 vp_md = 0; 1953 1954 /* 1955 * Mark the buffer clean. Increment the bufobj write count 1956 * before bundirty() call, to prevent other thread from seeing 1957 * empty dirty list and zero counter for writes in progress, 1958 * falsely indicating that the bufobj is clean. 1959 */ 1960 bufobj_wref(bp->b_bufobj); 1961 bundirty(bp); 1962 1963 bp->b_flags &= ~B_DONE; 1964 bp->b_ioflags &= ~BIO_ERROR; 1965 bp->b_flags |= B_CACHE; 1966 bp->b_iocmd = BIO_WRITE; 1967 1968 vfs_busy_pages(bp, 1); 1969 1970 /* 1971 * Normal bwrites pipeline writes 1972 */ 1973 bp->b_runningbufspace = bp->b_bufsize; 1974 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace); 1975 1976 if (!TD_IS_IDLETHREAD(curthread)) { 1977#ifdef RACCT 1978 if (racct_enable) { 1979 PROC_LOCK(curproc); 1980 racct_add_buf(curproc, bp, 1); 1981 PROC_UNLOCK(curproc); 1982 } 1983#endif /* RACCT */ 1984 curthread->td_ru.ru_oublock++; 1985 } 1986 if (oldflags & B_ASYNC) 1987 BUF_KERNPROC(bp); 1988 bp->b_iooffset = dbtob(bp->b_blkno); 1989 bstrategy(bp); 1990 1991 if ((oldflags & B_ASYNC) == 0) { 1992 int rtval = bufwait(bp); 1993 brelse(bp); 1994 return (rtval); 1995 } else if (space > hirunningspace) { 1996 /* 1997 * don't allow the async write to saturate the I/O 1998 * system. We will not deadlock here because 1999 * we are blocking waiting for I/O that is already in-progress 2000 * to complete. We do not block here if it is the update 2001 * or syncer daemon trying to clean up as that can lead 2002 * to deadlock. 2003 */ 2004 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 2005 waitrunningbufspace(); 2006 } 2007 2008 return (0); 2009} 2010 2011void 2012bufbdflush(struct bufobj *bo, struct buf *bp) 2013{ 2014 struct buf *nbp; 2015 2016 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 2017 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 2018 altbufferflushes++; 2019 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 2020 BO_LOCK(bo); 2021 /* 2022 * Try to find a buffer to flush. 2023 */ 2024 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 2025 if ((nbp->b_vflags & BV_BKGRDINPROG) || 2026 BUF_LOCK(nbp, 2027 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 2028 continue; 2029 if (bp == nbp) 2030 panic("bdwrite: found ourselves"); 2031 BO_UNLOCK(bo); 2032 /* Don't countdeps with the bo lock held. */ 2033 if (buf_countdeps(nbp, 0)) { 2034 BO_LOCK(bo); 2035 BUF_UNLOCK(nbp); 2036 continue; 2037 } 2038 if (nbp->b_flags & B_CLUSTEROK) { 2039 vfs_bio_awrite(nbp); 2040 } else { 2041 bremfree(nbp); 2042 bawrite(nbp); 2043 } 2044 dirtybufferflushes++; 2045 break; 2046 } 2047 if (nbp == NULL) 2048 BO_UNLOCK(bo); 2049 } 2050} 2051 2052/* 2053 * Delayed write. (Buffer is marked dirty). Do not bother writing 2054 * anything if the buffer is marked invalid. 2055 * 2056 * Note that since the buffer must be completely valid, we can safely 2057 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 2058 * biodone() in order to prevent getblk from writing the buffer 2059 * out synchronously. 2060 */ 2061void 2062bdwrite(struct buf *bp) 2063{ 2064 struct thread *td = curthread; 2065 struct vnode *vp; 2066 struct bufobj *bo; 2067 2068 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2069 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2070 KASSERT((bp->b_flags & B_BARRIER) == 0, 2071 ("Barrier request in delayed write %p", bp)); 2072 BUF_ASSERT_HELD(bp); 2073 2074 if (bp->b_flags & B_INVAL) { 2075 brelse(bp); 2076 return; 2077 } 2078 2079 /* 2080 * If we have too many dirty buffers, don't create any more. 2081 * If we are wildly over our limit, then force a complete 2082 * cleanup. Otherwise, just keep the situation from getting 2083 * out of control. Note that we have to avoid a recursive 2084 * disaster and not try to clean up after our own cleanup! 2085 */ 2086 vp = bp->b_vp; 2087 bo = bp->b_bufobj; 2088 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 2089 td->td_pflags |= TDP_INBDFLUSH; 2090 BO_BDFLUSH(bo, bp); 2091 td->td_pflags &= ~TDP_INBDFLUSH; 2092 } else 2093 recursiveflushes++; 2094 2095 bdirty(bp); 2096 /* 2097 * Set B_CACHE, indicating that the buffer is fully valid. This is 2098 * true even of NFS now. 2099 */ 2100 bp->b_flags |= B_CACHE; 2101 2102 /* 2103 * This bmap keeps the system from needing to do the bmap later, 2104 * perhaps when the system is attempting to do a sync. Since it 2105 * is likely that the indirect block -- or whatever other datastructure 2106 * that the filesystem needs is still in memory now, it is a good 2107 * thing to do this. Note also, that if the pageout daemon is 2108 * requesting a sync -- there might not be enough memory to do 2109 * the bmap then... So, this is important to do. 2110 */ 2111 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 2112 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 2113 } 2114 2115 /* 2116 * Set the *dirty* buffer range based upon the VM system dirty 2117 * pages. 2118 * 2119 * Mark the buffer pages as clean. We need to do this here to 2120 * satisfy the vnode_pager and the pageout daemon, so that it 2121 * thinks that the pages have been "cleaned". Note that since 2122 * the pages are in a delayed write buffer -- the VFS layer 2123 * "will" see that the pages get written out on the next sync, 2124 * or perhaps the cluster will be completed. 2125 */ 2126 vfs_clean_pages_dirty_buf(bp); 2127 bqrelse(bp); 2128 2129 /* 2130 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 2131 * due to the softdep code. 2132 */ 2133} 2134 2135/* 2136 * bdirty: 2137 * 2138 * Turn buffer into delayed write request. We must clear BIO_READ and 2139 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 2140 * itself to properly update it in the dirty/clean lists. We mark it 2141 * B_DONE to ensure that any asynchronization of the buffer properly 2142 * clears B_DONE ( else a panic will occur later ). 2143 * 2144 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 2145 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 2146 * should only be called if the buffer is known-good. 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 */ 2153void 2154bdirty(struct buf *bp) 2155{ 2156 2157 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 2158 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 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 2162 BUF_ASSERT_HELD(bp); 2163 bp->b_flags &= ~(B_RELBUF); 2164 bp->b_iocmd = BIO_WRITE; 2165 2166 if ((bp->b_flags & B_DELWRI) == 0) { 2167 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 2168 reassignbuf(bp); 2169 bdirtyadd(); 2170 } 2171} 2172 2173/* 2174 * bundirty: 2175 * 2176 * Clear B_DELWRI for buffer. 2177 * 2178 * Since the buffer is not on a queue, we do not update the numfreebuffers 2179 * count. 2180 * 2181 * The buffer must be on QUEUE_NONE. 2182 */ 2183 2184void 2185bundirty(struct buf *bp) 2186{ 2187 2188 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2189 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2190 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 2191 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 2192 BUF_ASSERT_HELD(bp); 2193 2194 if (bp->b_flags & B_DELWRI) { 2195 bp->b_flags &= ~B_DELWRI; 2196 reassignbuf(bp); 2197 bdirtysub(); 2198 } 2199 /* 2200 * Since it is now being written, we can clear its deferred write flag. 2201 */ 2202 bp->b_flags &= ~B_DEFERRED; 2203} 2204 2205/* 2206 * bawrite: 2207 * 2208 * Asynchronous write. Start output on a buffer, but do not wait for 2209 * it to complete. The buffer is released when the output completes. 2210 * 2211 * bwrite() ( or the VOP routine anyway ) is responsible for handling 2212 * B_INVAL buffers. Not us. 2213 */ 2214void 2215bawrite(struct buf *bp) 2216{ 2217 2218 bp->b_flags |= B_ASYNC; 2219 (void) bwrite(bp); 2220} 2221 2222/* 2223 * babarrierwrite: 2224 * 2225 * Asynchronous barrier write. Start output on a buffer, but do not 2226 * wait for it to complete. Place a write barrier after this write so 2227 * that this buffer and all buffers written before it are committed to 2228 * the disk before any buffers written after this write are committed 2229 * to the disk. The buffer is released when the output completes. 2230 */ 2231void 2232babarrierwrite(struct buf *bp) 2233{ 2234 2235 bp->b_flags |= B_ASYNC | B_BARRIER; 2236 (void) bwrite(bp); 2237} 2238 2239/* 2240 * bbarrierwrite: 2241 * 2242 * Synchronous barrier write. Start output on a buffer and wait for 2243 * it to complete. Place a write barrier after this write so that 2244 * this buffer and all buffers written before it are committed to 2245 * the disk before any buffers written after this write are committed 2246 * to the disk. The buffer is released when the output completes. 2247 */ 2248int 2249bbarrierwrite(struct buf *bp) 2250{ 2251 2252 bp->b_flags |= B_BARRIER; 2253 return (bwrite(bp)); 2254} 2255 2256/* 2257 * bwillwrite: 2258 * 2259 * Called prior to the locking of any vnodes when we are expecting to 2260 * write. We do not want to starve the buffer cache with too many 2261 * dirty buffers so we block here. By blocking prior to the locking 2262 * of any vnodes we attempt to avoid the situation where a locked vnode 2263 * prevents the various system daemons from flushing related buffers. 2264 */ 2265void 2266bwillwrite(void) 2267{ 2268 2269 if (numdirtybuffers >= hidirtybuffers) { 2270 mtx_lock(&bdirtylock); 2271 while (numdirtybuffers >= hidirtybuffers) { 2272 bdirtywait = 1; 2273 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4), 2274 "flswai", 0); 2275 } 2276 mtx_unlock(&bdirtylock); 2277 } 2278} 2279 2280/* 2281 * Return true if we have too many dirty buffers. 2282 */ 2283int 2284buf_dirty_count_severe(void) 2285{ 2286 2287 return(numdirtybuffers >= hidirtybuffers); 2288} 2289 2290/* 2291 * brelse: 2292 * 2293 * Release a busy buffer and, if requested, free its resources. The 2294 * buffer will be stashed in the appropriate bufqueue[] allowing it 2295 * to be accessed later as a cache entity or reused for other purposes. 2296 */ 2297void 2298brelse(struct buf *bp) 2299{ 2300 int qindex; 2301 2302 /* 2303 * Many functions erroneously call brelse with a NULL bp under rare 2304 * error conditions. Simply return when called with a NULL bp. 2305 */ 2306 if (bp == NULL) 2307 return; 2308 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 2309 bp, bp->b_vp, bp->b_flags); 2310 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 2311 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 2312 KASSERT((bp->b_flags & B_VMIO) != 0 || (bp->b_flags & B_NOREUSE) == 0, 2313 ("brelse: non-VMIO buffer marked NOREUSE")); 2314 2315 if (BUF_LOCKRECURSED(bp)) { 2316 /* 2317 * Do not process, in particular, do not handle the 2318 * B_INVAL/B_RELBUF and do not release to free list. 2319 */ 2320 BUF_UNLOCK(bp); 2321 return; 2322 } 2323 2324 if (bp->b_flags & B_MANAGED) { 2325 bqrelse(bp); 2326 return; 2327 } 2328 2329 if ((bp->b_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) { 2330 BO_LOCK(bp->b_bufobj); 2331 bp->b_vflags &= ~BV_BKGRDERR; 2332 BO_UNLOCK(bp->b_bufobj); 2333 bdirty(bp); 2334 } 2335 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 2336 (bp->b_error != ENXIO || !LIST_EMPTY(&bp->b_dep)) && 2337 !(bp->b_flags & B_INVAL)) { 2338 /* 2339 * Failed write, redirty. All errors except ENXIO (which 2340 * means the device is gone) are expected to be potentially 2341 * transient - underlying media might work if tried again 2342 * after EIO, and memory might be available after an ENOMEM. 2343 * 2344 * Do this also for buffers that failed with ENXIO, but have 2345 * non-empty dependencies - the soft updates code might need 2346 * to access the buffer to untangle them. 2347 * 2348 * Must clear BIO_ERROR to prevent pages from being scrapped. 2349 */ 2350 bp->b_ioflags &= ~BIO_ERROR; 2351 bdirty(bp); 2352 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 2353 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 2354 /* 2355 * Either a failed read I/O, or we were asked to free or not 2356 * cache the buffer, or we failed to write to a device that's 2357 * no longer present. 2358 */ 2359 bp->b_flags |= B_INVAL; 2360 if (!LIST_EMPTY(&bp->b_dep)) 2361 buf_deallocate(bp); 2362 if (bp->b_flags & B_DELWRI) 2363 bdirtysub(); 2364 bp->b_flags &= ~(B_DELWRI | B_CACHE); 2365 if ((bp->b_flags & B_VMIO) == 0) { 2366 allocbuf(bp, 0); 2367 if (bp->b_vp) 2368 brelvp(bp); 2369 } 2370 } 2371 2372 /* 2373 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_truncate() 2374 * is called with B_DELWRI set, the underlying pages may wind up 2375 * getting freed causing a previous write (bdwrite()) to get 'lost' 2376 * because pages associated with a B_DELWRI bp are marked clean. 2377 * 2378 * We still allow the B_INVAL case to call vfs_vmio_truncate(), even 2379 * if B_DELWRI is set. 2380 */ 2381 if (bp->b_flags & B_DELWRI) 2382 bp->b_flags &= ~B_RELBUF; 2383 2384 /* 2385 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 2386 * constituted, not even NFS buffers now. Two flags effect this. If 2387 * B_INVAL, the struct buf is invalidated but the VM object is kept 2388 * around ( i.e. so it is trivial to reconstitute the buffer later ). 2389 * 2390 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 2391 * invalidated. BIO_ERROR cannot be set for a failed write unless the 2392 * buffer is also B_INVAL because it hits the re-dirtying code above. 2393 * 2394 * Normally we can do this whether a buffer is B_DELWRI or not. If 2395 * the buffer is an NFS buffer, it is tracking piecemeal writes or 2396 * the commit state and we cannot afford to lose the buffer. If the 2397 * buffer has a background write in progress, we need to keep it 2398 * around to prevent it from being reconstituted and starting a second 2399 * background write. 2400 */ 2401 if ((bp->b_flags & B_VMIO) && (bp->b_flags & B_NOCACHE || 2402 (bp->b_ioflags & BIO_ERROR && bp->b_iocmd == BIO_READ)) && 2403 !(bp->b_vp->v_mount != NULL && 2404 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 2405 !vn_isdisk(bp->b_vp, NULL) && (bp->b_flags & B_DELWRI))) { 2406 vfs_vmio_invalidate(bp); 2407 allocbuf(bp, 0); 2408 } 2409 2410 if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0 || 2411 (bp->b_flags & (B_DELWRI | B_NOREUSE)) == B_NOREUSE) { 2412 allocbuf(bp, 0); 2413 bp->b_flags &= ~B_NOREUSE; 2414 if (bp->b_vp != NULL) 2415 brelvp(bp); 2416 } 2417 2418 /* 2419 * If the buffer has junk contents signal it and eventually 2420 * clean up B_DELWRI and diassociate the vnode so that gbincore() 2421 * doesn't find it. 2422 */ 2423 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 2424 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 2425 bp->b_flags |= B_INVAL; 2426 if (bp->b_flags & B_INVAL) { 2427 if (bp->b_flags & B_DELWRI) 2428 bundirty(bp); 2429 if (bp->b_vp) 2430 brelvp(bp); 2431 } 2432 2433 /* buffers with no memory */ 2434 if (bp->b_bufsize == 0) { 2435 buf_free(bp); 2436 return; 2437 } 2438 /* buffers with junk contents */ 2439 if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 2440 (bp->b_ioflags & BIO_ERROR)) { 2441 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 2442 if (bp->b_vflags & BV_BKGRDINPROG) 2443 panic("losing buffer 2"); 2444 qindex = QUEUE_CLEAN; 2445 bp->b_flags |= B_AGE; 2446 /* remaining buffers */ 2447 } else if (bp->b_flags & B_DELWRI) 2448 qindex = QUEUE_DIRTY; 2449 else 2450 qindex = QUEUE_CLEAN; 2451 2452 binsfree(bp, qindex); 2453 2454 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 2455 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 2456 panic("brelse: not dirty"); 2457 /* unlock */ 2458 BUF_UNLOCK(bp); 2459 if (qindex == QUEUE_CLEAN) 2460 bufspace_wakeup(); 2461} 2462 2463/* 2464 * Release a buffer back to the appropriate queue but do not try to free 2465 * it. The buffer is expected to be used again soon. 2466 * 2467 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 2468 * biodone() to requeue an async I/O on completion. It is also used when 2469 * known good buffers need to be requeued but we think we may need the data 2470 * again soon. 2471 * 2472 * XXX we should be able to leave the B_RELBUF hint set on completion. 2473 */ 2474void 2475bqrelse(struct buf *bp) 2476{ 2477 int qindex; 2478 2479 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2480 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 2481 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 2482 2483 qindex = QUEUE_NONE; 2484 if (BUF_LOCKRECURSED(bp)) { 2485 /* do not release to free list */ 2486 BUF_UNLOCK(bp); 2487 return; 2488 } 2489 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 2490 2491 if (bp->b_flags & B_MANAGED) { 2492 if (bp->b_flags & B_REMFREE) 2493 bremfreef(bp); 2494 goto out; 2495 } 2496 2497 /* buffers with stale but valid contents */ 2498 if ((bp->b_flags & B_DELWRI) != 0 || (bp->b_vflags & (BV_BKGRDINPROG | 2499 BV_BKGRDERR)) == BV_BKGRDERR) { 2500 BO_LOCK(bp->b_bufobj); 2501 bp->b_vflags &= ~BV_BKGRDERR; 2502 BO_UNLOCK(bp->b_bufobj); 2503 qindex = QUEUE_DIRTY; 2504 } else { 2505 if ((bp->b_flags & B_DELWRI) == 0 && 2506 (bp->b_xflags & BX_VNDIRTY)) 2507 panic("bqrelse: not dirty"); 2508 if ((bp->b_flags & B_NOREUSE) != 0) { 2509 brelse(bp); 2510 return; 2511 } 2512 qindex = QUEUE_CLEAN; 2513 } 2514 binsfree(bp, qindex); 2515 2516out: 2517 /* unlock */ 2518 BUF_UNLOCK(bp); 2519 if (qindex == QUEUE_CLEAN) 2520 bufspace_wakeup(); 2521} 2522 2523/* 2524 * Complete I/O to a VMIO backed page. Validate the pages as appropriate, 2525 * restore bogus pages. 2526 */ 2527static void 2528vfs_vmio_iodone(struct buf *bp) 2529{ 2530 vm_ooffset_t foff; 2531 vm_page_t m; 2532 vm_object_t obj; 2533 struct vnode *vp; 2534 int i, iosize, resid; 2535 bool bogus; 2536 2537 obj = bp->b_bufobj->bo_object; 2538 KASSERT(obj->paging_in_progress >= bp->b_npages, 2539 ("vfs_vmio_iodone: paging in progress(%d) < b_npages(%d)", 2540 obj->paging_in_progress, bp->b_npages)); 2541 2542 vp = bp->b_vp; 2543 KASSERT(vp->v_holdcnt > 0, 2544 ("vfs_vmio_iodone: vnode %p has zero hold count", vp)); 2545 KASSERT(vp->v_object != NULL, 2546 ("vfs_vmio_iodone: vnode %p has no vm_object", vp)); 2547 2548 foff = bp->b_offset; 2549 KASSERT(bp->b_offset != NOOFFSET, 2550 ("vfs_vmio_iodone: bp %p has no buffer offset", bp)); 2551 2552 bogus = false; 2553 iosize = bp->b_bcount - bp->b_resid; 2554 VM_OBJECT_WLOCK(obj); 2555 for (i = 0; i < bp->b_npages; i++) { 2556 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 2557 if (resid > iosize) 2558 resid = iosize; 2559 2560 /* 2561 * cleanup bogus pages, restoring the originals 2562 */ 2563 m = bp->b_pages[i]; 2564 if (m == bogus_page) { 2565 bogus = true; 2566 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 2567 if (m == NULL) 2568 panic("biodone: page disappeared!"); 2569 bp->b_pages[i] = m; 2570 } else if ((bp->b_iocmd == BIO_READ) && resid > 0) { 2571 /* 2572 * In the write case, the valid and clean bits are 2573 * already changed correctly ( see bdwrite() ), so we 2574 * only need to do this here in the read case. 2575 */ 2576 KASSERT((m->dirty & vm_page_bits(foff & PAGE_MASK, 2577 resid)) == 0, ("vfs_vmio_iodone: page %p " 2578 "has unexpected dirty bits", m)); 2579 vfs_page_set_valid(bp, foff, m); 2580 } 2581 KASSERT(OFF_TO_IDX(foff) == m->pindex, 2582 ("vfs_vmio_iodone: foff(%jd)/pindex(%ju) mismatch", 2583 (intmax_t)foff, (uintmax_t)m->pindex)); 2584 2585 vm_page_sunbusy(m); 2586 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2587 iosize -= resid; 2588 } 2589 vm_object_pip_wakeupn(obj, bp->b_npages); 2590 VM_OBJECT_WUNLOCK(obj); 2591 if (bogus && buf_mapped(bp)) { 2592 BUF_CHECK_MAPPED(bp); 2593 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 2594 bp->b_pages, bp->b_npages); 2595 } 2596} 2597 2598/* 2599 * Unwire a page held by a buf and place it on the appropriate vm queue. 2600 */ 2601static void 2602vfs_vmio_unwire(struct buf *bp, vm_page_t m) 2603{ 2604 bool freed; 2605 2606 vm_page_lock(m); 2607 if (vm_page_unwire(m, PQ_NONE)) { 2608 /* 2609 * Determine if the page should be freed before adding 2610 * it to the inactive queue. 2611 */ 2612 if (m->valid == 0) { 2613 freed = !vm_page_busied(m); 2614 if (freed) 2615 vm_page_free(m); 2616 } else if ((bp->b_flags & B_DIRECT) != 0) 2617 freed = vm_page_try_to_free(m); 2618 else 2619 freed = false; 2620 if (!freed) { 2621 /* 2622 * If the page is unlikely to be reused, let the 2623 * VM know. Otherwise, maintain LRU page 2624 * ordering and put the page at the tail of the 2625 * inactive queue. 2626 */ 2627 if ((bp->b_flags & B_NOREUSE) != 0) 2628 vm_page_deactivate_noreuse(m); 2629 else 2630 vm_page_deactivate(m); 2631 } 2632 } 2633 vm_page_unlock(m); 2634} 2635 2636/* 2637 * Perform page invalidation when a buffer is released. The fully invalid 2638 * pages will be reclaimed later in vfs_vmio_truncate(). 2639 */ 2640static void 2641vfs_vmio_invalidate(struct buf *bp) 2642{ 2643 vm_object_t obj; 2644 vm_page_t m; 2645 int i, resid, poffset, presid; 2646 2647 if (buf_mapped(bp)) { 2648 BUF_CHECK_MAPPED(bp); 2649 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages); 2650 } else 2651 BUF_CHECK_UNMAPPED(bp); 2652 /* 2653 * Get the base offset and length of the buffer. Note that 2654 * in the VMIO case if the buffer block size is not 2655 * page-aligned then b_data pointer may not be page-aligned. 2656 * But our b_pages[] array *IS* page aligned. 2657 * 2658 * block sizes less then DEV_BSIZE (usually 512) are not 2659 * supported due to the page granularity bits (m->valid, 2660 * m->dirty, etc...). 2661 * 2662 * See man buf(9) for more information 2663 */ 2664 obj = bp->b_bufobj->bo_object; 2665 resid = bp->b_bufsize; 2666 poffset = bp->b_offset & PAGE_MASK; 2667 VM_OBJECT_WLOCK(obj); 2668 for (i = 0; i < bp->b_npages; i++) { 2669 m = bp->b_pages[i]; 2670 if (m == bogus_page) 2671 panic("vfs_vmio_invalidate: Unexpected bogus page."); 2672 bp->b_pages[i] = NULL; 2673 2674 presid = resid > (PAGE_SIZE - poffset) ? 2675 (PAGE_SIZE - poffset) : resid; 2676 KASSERT(presid >= 0, ("brelse: extra page")); 2677 while (vm_page_xbusied(m)) { 2678 vm_page_lock(m); 2679 VM_OBJECT_WUNLOCK(obj); 2680 vm_page_busy_sleep(m, "mbncsh", true); 2681 VM_OBJECT_WLOCK(obj); 2682 } 2683 if (pmap_page_wired_mappings(m) == 0) 2684 vm_page_set_invalid(m, poffset, presid); 2685 vfs_vmio_unwire(bp, m); 2686 resid -= presid; 2687 poffset = 0; 2688 } 2689 VM_OBJECT_WUNLOCK(obj); 2690 bp->b_npages = 0; 2691} 2692 2693/* 2694 * Page-granular truncation of an existing VMIO buffer. 2695 */ 2696static void 2697vfs_vmio_truncate(struct buf *bp, int desiredpages) 2698{ 2699 vm_object_t obj; 2700 vm_page_t m; 2701 int i; 2702 2703 if (bp->b_npages == desiredpages) 2704 return; 2705 2706 if (buf_mapped(bp)) { 2707 BUF_CHECK_MAPPED(bp); 2708 pmap_qremove((vm_offset_t)trunc_page((vm_offset_t)bp->b_data) + 2709 (desiredpages << PAGE_SHIFT), bp->b_npages - desiredpages); 2710 } else 2711 BUF_CHECK_UNMAPPED(bp); 2712 obj = bp->b_bufobj->bo_object; 2713 if (obj != NULL) 2714 VM_OBJECT_WLOCK(obj); 2715 for (i = desiredpages; i < bp->b_npages; i++) { 2716 m = bp->b_pages[i]; 2717 KASSERT(m != bogus_page, ("allocbuf: bogus page found")); 2718 bp->b_pages[i] = NULL; 2719 vfs_vmio_unwire(bp, m); 2720 } 2721 if (obj != NULL) 2722 VM_OBJECT_WUNLOCK(obj); 2723 bp->b_npages = desiredpages; 2724} 2725 2726/* 2727 * Byte granular extension of VMIO buffers. 2728 */ 2729static void 2730vfs_vmio_extend(struct buf *bp, int desiredpages, int size) 2731{ 2732 /* 2733 * We are growing the buffer, possibly in a 2734 * byte-granular fashion. 2735 */ 2736 vm_object_t obj; 2737 vm_offset_t toff; 2738 vm_offset_t tinc; 2739 vm_page_t m; 2740 2741 /* 2742 * Step 1, bring in the VM pages from the object, allocating 2743 * them if necessary. We must clear B_CACHE if these pages 2744 * are not valid for the range covered by the buffer. 2745 */ 2746 obj = bp->b_bufobj->bo_object; 2747 VM_OBJECT_WLOCK(obj); 2748 if (bp->b_npages < desiredpages) { 2749 /* 2750 * We must allocate system pages since blocking 2751 * here could interfere with paging I/O, no 2752 * matter which process we are. 2753 * 2754 * Only exclusive busy can be tested here. 2755 * Blocking on shared busy might lead to 2756 * deadlocks once allocbuf() is called after 2757 * pages are vfs_busy_pages(). 2758 */ 2759 (void)vm_page_grab_pages(obj, 2760 OFF_TO_IDX(bp->b_offset) + bp->b_npages, 2761 VM_ALLOC_SYSTEM | VM_ALLOC_IGN_SBUSY | 2762 VM_ALLOC_NOBUSY | VM_ALLOC_WIRED, 2763 &bp->b_pages[bp->b_npages], desiredpages - bp->b_npages); 2764 bp->b_npages = desiredpages; 2765 } 2766 2767 /* 2768 * Step 2. We've loaded the pages into the buffer, 2769 * we have to figure out if we can still have B_CACHE 2770 * set. Note that B_CACHE is set according to the 2771 * byte-granular range ( bcount and size ), not the 2772 * aligned range ( newbsize ). 2773 * 2774 * The VM test is against m->valid, which is DEV_BSIZE 2775 * aligned. Needless to say, the validity of the data 2776 * needs to also be DEV_BSIZE aligned. Note that this 2777 * fails with NFS if the server or some other client 2778 * extends the file's EOF. If our buffer is resized, 2779 * B_CACHE may remain set! XXX 2780 */ 2781 toff = bp->b_bcount; 2782 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 2783 while ((bp->b_flags & B_CACHE) && toff < size) { 2784 vm_pindex_t pi; 2785 2786 if (tinc > (size - toff)) 2787 tinc = size - toff; 2788 pi = ((bp->b_offset & PAGE_MASK) + toff) >> PAGE_SHIFT; 2789 m = bp->b_pages[pi]; 2790 vfs_buf_test_cache(bp, bp->b_offset, toff, tinc, m); 2791 toff += tinc; 2792 tinc = PAGE_SIZE; 2793 } 2794 VM_OBJECT_WUNLOCK(obj); 2795 2796 /* 2797 * Step 3, fixup the KVA pmap. 2798 */ 2799 if (buf_mapped(bp)) 2800 bpmap_qenter(bp); 2801 else 2802 BUF_CHECK_UNMAPPED(bp); 2803} 2804 2805/* 2806 * Check to see if a block at a particular lbn is available for a clustered 2807 * write. 2808 */ 2809static int 2810vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 2811{ 2812 struct buf *bpa; 2813 int match; 2814 2815 match = 0; 2816 2817 /* If the buf isn't in core skip it */ 2818 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 2819 return (0); 2820 2821 /* If the buf is busy we don't want to wait for it */ 2822 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2823 return (0); 2824 2825 /* Only cluster with valid clusterable delayed write buffers */ 2826 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 2827 (B_DELWRI | B_CLUSTEROK)) 2828 goto done; 2829 2830 if (bpa->b_bufsize != size) 2831 goto done; 2832 2833 /* 2834 * Check to see if it is in the expected place on disk and that the 2835 * block has been mapped. 2836 */ 2837 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 2838 match = 1; 2839done: 2840 BUF_UNLOCK(bpa); 2841 return (match); 2842} 2843 2844/* 2845 * vfs_bio_awrite: 2846 * 2847 * Implement clustered async writes for clearing out B_DELWRI buffers. 2848 * This is much better then the old way of writing only one buffer at 2849 * a time. Note that we may not be presented with the buffers in the 2850 * correct order, so we search for the cluster in both directions. 2851 */ 2852int 2853vfs_bio_awrite(struct buf *bp) 2854{ 2855 struct bufobj *bo; 2856 int i; 2857 int j; 2858 daddr_t lblkno = bp->b_lblkno; 2859 struct vnode *vp = bp->b_vp; 2860 int ncl; 2861 int nwritten; 2862 int size; 2863 int maxcl; 2864 int gbflags; 2865 2866 bo = &vp->v_bufobj; 2867 gbflags = (bp->b_data == unmapped_buf) ? GB_UNMAPPED : 0; 2868 /* 2869 * right now we support clustered writing only to regular files. If 2870 * we find a clusterable block we could be in the middle of a cluster 2871 * rather then at the beginning. 2872 */ 2873 if ((vp->v_type == VREG) && 2874 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 2875 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 2876 2877 size = vp->v_mount->mnt_stat.f_iosize; 2878 maxcl = MAXPHYS / size; 2879 2880 BO_RLOCK(bo); 2881 for (i = 1; i < maxcl; i++) 2882 if (vfs_bio_clcheck(vp, size, lblkno + i, 2883 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 2884 break; 2885 2886 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 2887 if (vfs_bio_clcheck(vp, size, lblkno - j, 2888 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 2889 break; 2890 BO_RUNLOCK(bo); 2891 --j; 2892 ncl = i + j; 2893 /* 2894 * this is a possible cluster write 2895 */ 2896 if (ncl != 1) { 2897 BUF_UNLOCK(bp); 2898 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl, 2899 gbflags); 2900 return (nwritten); 2901 } 2902 } 2903 bremfree(bp); 2904 bp->b_flags |= B_ASYNC; 2905 /* 2906 * default (old) behavior, writing out only one block 2907 * 2908 * XXX returns b_bufsize instead of b_bcount for nwritten? 2909 */ 2910 nwritten = bp->b_bufsize; 2911 (void) bwrite(bp); 2912 2913 return (nwritten); 2914} 2915 2916/* 2917 * getnewbuf_kva: 2918 * 2919 * Allocate KVA for an empty buf header according to gbflags. 2920 */ 2921static int 2922getnewbuf_kva(struct buf *bp, int gbflags, int maxsize) 2923{ 2924 2925 if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_UNMAPPED) { 2926 /* 2927 * In order to keep fragmentation sane we only allocate kva 2928 * in BKVASIZE chunks. XXX with vmem we can do page size. 2929 */ 2930 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2931 2932 if (maxsize != bp->b_kvasize && 2933 bufkva_alloc(bp, maxsize, gbflags)) 2934 return (ENOSPC); 2935 } 2936 return (0); 2937} 2938 2939/* 2940 * getnewbuf: 2941 * 2942 * Find and initialize a new buffer header, freeing up existing buffers 2943 * in the bufqueues as necessary. The new buffer is returned locked. 2944 * 2945 * We block if: 2946 * We have insufficient buffer headers 2947 * We have insufficient buffer space 2948 * buffer_arena is too fragmented ( space reservation fails ) 2949 * If we have to flush dirty buffers ( but we try to avoid this ) 2950 * 2951 * The caller is responsible for releasing the reserved bufspace after 2952 * allocbuf() is called. 2953 */ 2954static struct buf * 2955getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int maxsize, int gbflags) 2956{ 2957 struct buf *bp; 2958 bool metadata, reserved; 2959 2960 bp = NULL; 2961 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 2962 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 2963 if (!unmapped_buf_allowed) 2964 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC); 2965 2966 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 || 2967 vp->v_type == VCHR) 2968 metadata = true; 2969 else 2970 metadata = false; 2971 atomic_add_int(&getnewbufcalls, 1); 2972 reserved = false; 2973 do { 2974 if (reserved == false && 2975 bufspace_reserve(maxsize, metadata) != 0) 2976 continue; 2977 reserved = true; 2978 if ((bp = buf_alloc()) == NULL) 2979 continue; 2980 if (getnewbuf_kva(bp, gbflags, maxsize) == 0) 2981 return (bp); 2982 break; 2983 } while(buf_scan(false) == 0); 2984 2985 if (reserved) 2986 atomic_subtract_long(&bufspace, maxsize); 2987 if (bp != NULL) { 2988 bp->b_flags |= B_INVAL; 2989 brelse(bp); 2990 } 2991 bufspace_wait(vp, gbflags, slpflag, slptimeo); 2992 2993 return (NULL); 2994} 2995 2996/* 2997 * buf_daemon: 2998 * 2999 * buffer flushing daemon. Buffers are normally flushed by the 3000 * update daemon but if it cannot keep up this process starts to 3001 * take the load in an attempt to prevent getnewbuf() from blocking. 3002 */ 3003static struct kproc_desc buf_kp = { 3004 "bufdaemon", 3005 buf_daemon, 3006 &bufdaemonproc 3007}; 3008SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 3009 3010static int 3011buf_flush(struct vnode *vp, int target) 3012{ 3013 int flushed; 3014 3015 flushed = flushbufqueues(vp, target, 0); 3016 if (flushed == 0) { 3017 /* 3018 * Could not find any buffers without rollback 3019 * dependencies, so just write the first one 3020 * in the hopes of eventually making progress. 3021 */ 3022 if (vp != NULL && target > 2) 3023 target /= 2; 3024 flushbufqueues(vp, target, 1); 3025 } 3026 return (flushed); 3027} 3028 3029static void 3030buf_daemon() 3031{ 3032 int lodirty; 3033 3034 /* 3035 * This process needs to be suspended prior to shutdown sync. 3036 */ 3037 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 3038 SHUTDOWN_PRI_LAST); 3039 3040 /* 3041 * This process is allowed to take the buffer cache to the limit 3042 */ 3043 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 3044 mtx_lock(&bdlock); 3045 for (;;) { 3046 bd_request = 0; 3047 mtx_unlock(&bdlock); 3048 3049 kproc_suspend_check(bufdaemonproc); 3050 lodirty = lodirtybuffers; 3051 if (bd_speedupreq) { 3052 lodirty = numdirtybuffers / 2; 3053 bd_speedupreq = 0; 3054 } 3055 /* 3056 * Do the flush. Limit the amount of in-transit I/O we 3057 * allow to build up, otherwise we would completely saturate 3058 * the I/O system. 3059 */ 3060 while (numdirtybuffers > lodirty) { 3061 if (buf_flush(NULL, numdirtybuffers - lodirty) == 0) 3062 break; 3063 kern_yield(PRI_USER); 3064 } 3065 3066 /* 3067 * Only clear bd_request if we have reached our low water 3068 * mark. The buf_daemon normally waits 1 second and 3069 * then incrementally flushes any dirty buffers that have 3070 * built up, within reason. 3071 * 3072 * If we were unable to hit our low water mark and couldn't 3073 * find any flushable buffers, we sleep for a short period 3074 * to avoid endless loops on unlockable buffers. 3075 */ 3076 mtx_lock(&bdlock); 3077 if (numdirtybuffers <= lodirtybuffers) { 3078 /* 3079 * We reached our low water mark, reset the 3080 * request and sleep until we are needed again. 3081 * The sleep is just so the suspend code works. 3082 */ 3083 bd_request = 0; 3084 /* 3085 * Do an extra wakeup in case dirty threshold 3086 * changed via sysctl and the explicit transition 3087 * out of shortfall was missed. 3088 */ 3089 bdirtywakeup(); 3090 if (runningbufspace <= lorunningspace) 3091 runningwakeup(); 3092 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 3093 } else { 3094 /* 3095 * We couldn't find any flushable dirty buffers but 3096 * still have too many dirty buffers, we 3097 * have to sleep and try again. (rare) 3098 */ 3099 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 3100 } 3101 } 3102} 3103 3104/* 3105 * flushbufqueues: 3106 * 3107 * Try to flush a buffer in the dirty queue. We must be careful to 3108 * free up B_INVAL buffers instead of write them, which NFS is 3109 * particularly sensitive to. 3110 */ 3111static int flushwithdeps = 0; 3112SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 3113 0, "Number of buffers flushed with dependecies that require rollbacks"); 3114 3115static int 3116flushbufqueues(struct vnode *lvp, int target, int flushdeps) 3117{ 3118 struct buf *sentinel; 3119 struct vnode *vp; 3120 struct mount *mp; 3121 struct buf *bp; 3122 int hasdeps; 3123 int flushed; 3124 int queue; 3125 int error; 3126 bool unlock; 3127 3128 flushed = 0; 3129 queue = QUEUE_DIRTY; 3130 bp = NULL; 3131 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 3132 sentinel->b_qindex = QUEUE_SENTINEL; 3133 mtx_lock(&bqlocks[queue]); 3134 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist); 3135 mtx_unlock(&bqlocks[queue]); 3136 while (flushed != target) { 3137 maybe_yield(); 3138 mtx_lock(&bqlocks[queue]); 3139 bp = TAILQ_NEXT(sentinel, b_freelist); 3140 if (bp != NULL) { 3141 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 3142 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel, 3143 b_freelist); 3144 } else { 3145 mtx_unlock(&bqlocks[queue]); 3146 break; 3147 } 3148 /* 3149 * Skip sentinels inserted by other invocations of the 3150 * flushbufqueues(), taking care to not reorder them. 3151 * 3152 * Only flush the buffers that belong to the 3153 * vnode locked by the curthread. 3154 */ 3155 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL && 3156 bp->b_vp != lvp)) { 3157 mtx_unlock(&bqlocks[queue]); 3158 continue; 3159 } 3160 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL); 3161 mtx_unlock(&bqlocks[queue]); 3162 if (error != 0) 3163 continue; 3164 if (bp->b_pin_count > 0) { 3165 BUF_UNLOCK(bp); 3166 continue; 3167 } 3168 /* 3169 * BKGRDINPROG can only be set with the buf and bufobj 3170 * locks both held. We tolerate a race to clear it here. 3171 */ 3172 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 3173 (bp->b_flags & B_DELWRI) == 0) { 3174 BUF_UNLOCK(bp); 3175 continue; 3176 } 3177 if (bp->b_flags & B_INVAL) { 3178 bremfreef(bp); 3179 brelse(bp); 3180 flushed++; 3181 continue; 3182 } 3183 3184 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 3185 if (flushdeps == 0) { 3186 BUF_UNLOCK(bp); 3187 continue; 3188 } 3189 hasdeps = 1; 3190 } else 3191 hasdeps = 0; 3192 /* 3193 * We must hold the lock on a vnode before writing 3194 * one of its buffers. Otherwise we may confuse, or 3195 * in the case of a snapshot vnode, deadlock the 3196 * system. 3197 * 3198 * The lock order here is the reverse of the normal 3199 * of vnode followed by buf lock. This is ok because 3200 * the NOWAIT will prevent deadlock. 3201 */ 3202 vp = bp->b_vp; 3203 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 3204 BUF_UNLOCK(bp); 3205 continue; 3206 } 3207 if (lvp == NULL) { 3208 unlock = true; 3209 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT); 3210 } else { 3211 ASSERT_VOP_LOCKED(vp, "getbuf"); 3212 unlock = false; 3213 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 : 3214 vn_lock(vp, LK_TRYUPGRADE); 3215 } 3216 if (error == 0) { 3217 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 3218 bp, bp->b_vp, bp->b_flags); 3219 if (curproc == bufdaemonproc) { 3220 vfs_bio_awrite(bp); 3221 } else { 3222 bremfree(bp); 3223 bwrite(bp); 3224 notbufdflushes++; 3225 } 3226 vn_finished_write(mp); 3227 if (unlock) 3228 VOP_UNLOCK(vp, 0); 3229 flushwithdeps += hasdeps; 3230 flushed++; 3231 3232 /* 3233 * Sleeping on runningbufspace while holding 3234 * vnode lock leads to deadlock. 3235 */ 3236 if (curproc == bufdaemonproc && 3237 runningbufspace > hirunningspace) 3238 waitrunningbufspace(); 3239 continue; 3240 } 3241 vn_finished_write(mp); 3242 BUF_UNLOCK(bp); 3243 } 3244 mtx_lock(&bqlocks[queue]); 3245 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 3246 mtx_unlock(&bqlocks[queue]); 3247 free(sentinel, M_TEMP); 3248 return (flushed); 3249} 3250 3251/* 3252 * Check to see if a block is currently memory resident. 3253 */ 3254struct buf * 3255incore(struct bufobj *bo, daddr_t blkno) 3256{ 3257 struct buf *bp; 3258 3259 BO_RLOCK(bo); 3260 bp = gbincore(bo, blkno); 3261 BO_RUNLOCK(bo); 3262 return (bp); 3263} 3264 3265/* 3266 * Returns true if no I/O is needed to access the 3267 * associated VM object. This is like incore except 3268 * it also hunts around in the VM system for the data. 3269 */ 3270 3271static int 3272inmem(struct vnode * vp, daddr_t blkno) 3273{ 3274 vm_object_t obj; 3275 vm_offset_t toff, tinc, size; 3276 vm_page_t m; 3277 vm_ooffset_t off; 3278 3279 ASSERT_VOP_LOCKED(vp, "inmem"); 3280 3281 if (incore(&vp->v_bufobj, blkno)) 3282 return 1; 3283 if (vp->v_mount == NULL) 3284 return 0; 3285 obj = vp->v_object; 3286 if (obj == NULL) 3287 return (0); 3288 3289 size = PAGE_SIZE; 3290 if (size > vp->v_mount->mnt_stat.f_iosize) 3291 size = vp->v_mount->mnt_stat.f_iosize; 3292 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 3293 3294 VM_OBJECT_RLOCK(obj); 3295 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 3296 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 3297 if (!m) 3298 goto notinmem; 3299 tinc = size; 3300 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 3301 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 3302 if (vm_page_is_valid(m, 3303 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 3304 goto notinmem; 3305 } 3306 VM_OBJECT_RUNLOCK(obj); 3307 return 1; 3308 3309notinmem: 3310 VM_OBJECT_RUNLOCK(obj); 3311 return (0); 3312} 3313 3314/* 3315 * Set the dirty range for a buffer based on the status of the dirty 3316 * bits in the pages comprising the buffer. The range is limited 3317 * to the size of the buffer. 3318 * 3319 * Tell the VM system that the pages associated with this buffer 3320 * are clean. This is used for delayed writes where the data is 3321 * going to go to disk eventually without additional VM intevention. 3322 * 3323 * Note that while we only really need to clean through to b_bcount, we 3324 * just go ahead and clean through to b_bufsize. 3325 */ 3326static void 3327vfs_clean_pages_dirty_buf(struct buf *bp) 3328{ 3329 vm_ooffset_t foff, noff, eoff; 3330 vm_page_t m; 3331 int i; 3332 3333 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 3334 return; 3335 3336 foff = bp->b_offset; 3337 KASSERT(bp->b_offset != NOOFFSET, 3338 ("vfs_clean_pages_dirty_buf: no buffer offset")); 3339 3340 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 3341 vfs_drain_busy_pages(bp); 3342 vfs_setdirty_locked_object(bp); 3343 for (i = 0; i < bp->b_npages; i++) { 3344 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3345 eoff = noff; 3346 if (eoff > bp->b_offset + bp->b_bufsize) 3347 eoff = bp->b_offset + bp->b_bufsize; 3348 m = bp->b_pages[i]; 3349 vfs_page_set_validclean(bp, foff, m); 3350 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3351 foff = noff; 3352 } 3353 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 3354} 3355 3356static void 3357vfs_setdirty_locked_object(struct buf *bp) 3358{ 3359 vm_object_t object; 3360 int i; 3361 3362 object = bp->b_bufobj->bo_object; 3363 VM_OBJECT_ASSERT_WLOCKED(object); 3364 3365 /* 3366 * We qualify the scan for modified pages on whether the 3367 * object has been flushed yet. 3368 */ 3369 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) { 3370 vm_offset_t boffset; 3371 vm_offset_t eoffset; 3372 3373 /* 3374 * test the pages to see if they have been modified directly 3375 * by users through the VM system. 3376 */ 3377 for (i = 0; i < bp->b_npages; i++) 3378 vm_page_test_dirty(bp->b_pages[i]); 3379 3380 /* 3381 * Calculate the encompassing dirty range, boffset and eoffset, 3382 * (eoffset - boffset) bytes. 3383 */ 3384 3385 for (i = 0; i < bp->b_npages; i++) { 3386 if (bp->b_pages[i]->dirty) 3387 break; 3388 } 3389 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3390 3391 for (i = bp->b_npages - 1; i >= 0; --i) { 3392 if (bp->b_pages[i]->dirty) { 3393 break; 3394 } 3395 } 3396 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3397 3398 /* 3399 * Fit it to the buffer. 3400 */ 3401 3402 if (eoffset > bp->b_bcount) 3403 eoffset = bp->b_bcount; 3404 3405 /* 3406 * If we have a good dirty range, merge with the existing 3407 * dirty range. 3408 */ 3409 3410 if (boffset < eoffset) { 3411 if (bp->b_dirtyoff > boffset) 3412 bp->b_dirtyoff = boffset; 3413 if (bp->b_dirtyend < eoffset) 3414 bp->b_dirtyend = eoffset; 3415 } 3416 } 3417} 3418 3419/* 3420 * Allocate the KVA mapping for an existing buffer. 3421 * If an unmapped buffer is provided but a mapped buffer is requested, take 3422 * also care to properly setup mappings between pages and KVA. 3423 */ 3424static void 3425bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags) 3426{ 3427 int bsize, maxsize, need_mapping, need_kva; 3428 off_t offset; 3429 3430 need_mapping = bp->b_data == unmapped_buf && 3431 (gbflags & GB_UNMAPPED) == 0; 3432 need_kva = bp->b_kvabase == unmapped_buf && 3433 bp->b_data == unmapped_buf && 3434 (gbflags & GB_KVAALLOC) != 0; 3435 if (!need_mapping && !need_kva) 3436 return; 3437 3438 BUF_CHECK_UNMAPPED(bp); 3439 3440 if (need_mapping && bp->b_kvabase != unmapped_buf) { 3441 /* 3442 * Buffer is not mapped, but the KVA was already 3443 * reserved at the time of the instantiation. Use the 3444 * allocated space. 3445 */ 3446 goto has_addr; 3447 } 3448 3449 /* 3450 * Calculate the amount of the address space we would reserve 3451 * if the buffer was mapped. 3452 */ 3453 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize; 3454 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3455 offset = blkno * bsize; 3456 maxsize = size + (offset & PAGE_MASK); 3457 maxsize = imax(maxsize, bsize); 3458 3459 while (bufkva_alloc(bp, maxsize, gbflags) != 0) { 3460 if ((gbflags & GB_NOWAIT_BD) != 0) { 3461 /* 3462 * XXXKIB: defragmentation cannot 3463 * succeed, not sure what else to do. 3464 */ 3465 panic("GB_NOWAIT_BD and GB_UNMAPPED %p", bp); 3466 } 3467 atomic_add_int(&mappingrestarts, 1); 3468 bufspace_wait(bp->b_vp, gbflags, 0, 0); 3469 } 3470has_addr: 3471 if (need_mapping) { 3472 /* b_offset is handled by bpmap_qenter. */ 3473 bp->b_data = bp->b_kvabase; 3474 BUF_CHECK_MAPPED(bp); 3475 bpmap_qenter(bp); 3476 } 3477} 3478 3479/* 3480 * getblk: 3481 * 3482 * Get a block given a specified block and offset into a file/device. 3483 * The buffers B_DONE bit will be cleared on return, making it almost 3484 * ready for an I/O initiation. B_INVAL may or may not be set on 3485 * return. The caller should clear B_INVAL prior to initiating a 3486 * READ. 3487 * 3488 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 3489 * an existing buffer. 3490 * 3491 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 3492 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 3493 * and then cleared based on the backing VM. If the previous buffer is 3494 * non-0-sized but invalid, B_CACHE will be cleared. 3495 * 3496 * If getblk() must create a new buffer, the new buffer is returned with 3497 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 3498 * case it is returned with B_INVAL clear and B_CACHE set based on the 3499 * backing VM. 3500 * 3501 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 3502 * B_CACHE bit is clear. 3503 * 3504 * What this means, basically, is that the caller should use B_CACHE to 3505 * determine whether the buffer is fully valid or not and should clear 3506 * B_INVAL prior to issuing a read. If the caller intends to validate 3507 * the buffer by loading its data area with something, the caller needs 3508 * to clear B_INVAL. If the caller does this without issuing an I/O, 3509 * the caller should set B_CACHE ( as an optimization ), else the caller 3510 * should issue the I/O and biodone() will set B_CACHE if the I/O was 3511 * a write attempt or if it was a successful read. If the caller 3512 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 3513 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 3514 */ 3515struct buf * 3516getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3517 int flags) 3518{ 3519 struct buf *bp; 3520 struct bufobj *bo; 3521 int bsize, error, maxsize, vmio; 3522 off_t offset; 3523 3524 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 3525 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3526 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3527 ASSERT_VOP_LOCKED(vp, "getblk"); 3528 if (size > maxbcachebuf) 3529 panic("getblk: size(%d) > maxbcachebuf(%d)\n", size, 3530 maxbcachebuf); 3531 if (!unmapped_buf_allowed) 3532 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3533 3534 bo = &vp->v_bufobj; 3535loop: 3536 BO_RLOCK(bo); 3537 bp = gbincore(bo, blkno); 3538 if (bp != NULL) { 3539 int lockflags; 3540 /* 3541 * Buffer is in-core. If the buffer is not busy nor managed, 3542 * it must be on a queue. 3543 */ 3544 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 3545 3546 if (flags & GB_LOCK_NOWAIT) 3547 lockflags |= LK_NOWAIT; 3548 3549 error = BUF_TIMELOCK(bp, lockflags, 3550 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo); 3551 3552 /* 3553 * If we slept and got the lock we have to restart in case 3554 * the buffer changed identities. 3555 */ 3556 if (error == ENOLCK) 3557 goto loop; 3558 /* We timed out or were interrupted. */ 3559 else if (error) 3560 return (NULL); 3561 /* If recursed, assume caller knows the rules. */ 3562 else if (BUF_LOCKRECURSED(bp)) 3563 goto end; 3564 3565 /* 3566 * The buffer is locked. B_CACHE is cleared if the buffer is 3567 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 3568 * and for a VMIO buffer B_CACHE is adjusted according to the 3569 * backing VM cache. 3570 */ 3571 if (bp->b_flags & B_INVAL) 3572 bp->b_flags &= ~B_CACHE; 3573 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 3574 bp->b_flags |= B_CACHE; 3575 if (bp->b_flags & B_MANAGED) 3576 MPASS(bp->b_qindex == QUEUE_NONE); 3577 else 3578 bremfree(bp); 3579 3580 /* 3581 * check for size inconsistencies for non-VMIO case. 3582 */ 3583 if (bp->b_bcount != size) { 3584 if ((bp->b_flags & B_VMIO) == 0 || 3585 (size > bp->b_kvasize)) { 3586 if (bp->b_flags & B_DELWRI) { 3587 /* 3588 * If buffer is pinned and caller does 3589 * not want sleep waiting for it to be 3590 * unpinned, bail out 3591 * */ 3592 if (bp->b_pin_count > 0) { 3593 if (flags & GB_LOCK_NOWAIT) { 3594 bqrelse(bp); 3595 return (NULL); 3596 } else { 3597 bunpin_wait(bp); 3598 } 3599 } 3600 bp->b_flags |= B_NOCACHE; 3601 bwrite(bp); 3602 } else { 3603 if (LIST_EMPTY(&bp->b_dep)) { 3604 bp->b_flags |= B_RELBUF; 3605 brelse(bp); 3606 } else { 3607 bp->b_flags |= B_NOCACHE; 3608 bwrite(bp); 3609 } 3610 } 3611 goto loop; 3612 } 3613 } 3614 3615 /* 3616 * Handle the case of unmapped buffer which should 3617 * become mapped, or the buffer for which KVA 3618 * reservation is requested. 3619 */ 3620 bp_unmapped_get_kva(bp, blkno, size, flags); 3621 3622 /* 3623 * If the size is inconsistent in the VMIO case, we can resize 3624 * the buffer. This might lead to B_CACHE getting set or 3625 * cleared. If the size has not changed, B_CACHE remains 3626 * unchanged from its previous state. 3627 */ 3628 allocbuf(bp, size); 3629 3630 KASSERT(bp->b_offset != NOOFFSET, 3631 ("getblk: no buffer offset")); 3632 3633 /* 3634 * A buffer with B_DELWRI set and B_CACHE clear must 3635 * be committed before we can return the buffer in 3636 * order to prevent the caller from issuing a read 3637 * ( due to B_CACHE not being set ) and overwriting 3638 * it. 3639 * 3640 * Most callers, including NFS and FFS, need this to 3641 * operate properly either because they assume they 3642 * can issue a read if B_CACHE is not set, or because 3643 * ( for example ) an uncached B_DELWRI might loop due 3644 * to softupdates re-dirtying the buffer. In the latter 3645 * case, B_CACHE is set after the first write completes, 3646 * preventing further loops. 3647 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 3648 * above while extending the buffer, we cannot allow the 3649 * buffer to remain with B_CACHE set after the write 3650 * completes or it will represent a corrupt state. To 3651 * deal with this we set B_NOCACHE to scrap the buffer 3652 * after the write. 3653 * 3654 * We might be able to do something fancy, like setting 3655 * B_CACHE in bwrite() except if B_DELWRI is already set, 3656 * so the below call doesn't set B_CACHE, but that gets real 3657 * confusing. This is much easier. 3658 */ 3659 3660 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 3661 bp->b_flags |= B_NOCACHE; 3662 bwrite(bp); 3663 goto loop; 3664 } 3665 bp->b_flags &= ~B_DONE; 3666 } else { 3667 /* 3668 * Buffer is not in-core, create new buffer. The buffer 3669 * returned by getnewbuf() is locked. Note that the returned 3670 * buffer is also considered valid (not marked B_INVAL). 3671 */ 3672 BO_RUNLOCK(bo); 3673 /* 3674 * If the user does not want us to create the buffer, bail out 3675 * here. 3676 */ 3677 if (flags & GB_NOCREAT) 3678 return NULL; 3679 if (numfreebuffers == 0 && TD_IS_IDLETHREAD(curthread)) 3680 return NULL; 3681 3682 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize; 3683 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3684 offset = blkno * bsize; 3685 vmio = vp->v_object != NULL; 3686 if (vmio) { 3687 maxsize = size + (offset & PAGE_MASK); 3688 } else { 3689 maxsize = size; 3690 /* Do not allow non-VMIO notmapped buffers. */ 3691 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3692 } 3693 maxsize = imax(maxsize, bsize); 3694 3695 bp = getnewbuf(vp, slpflag, slptimeo, maxsize, flags); 3696 if (bp == NULL) { 3697 if (slpflag || slptimeo) 3698 return NULL; 3699 /* 3700 * XXX This is here until the sleep path is diagnosed 3701 * enough to work under very low memory conditions. 3702 * 3703 * There's an issue on low memory, 4BSD+non-preempt 3704 * systems (eg MIPS routers with 32MB RAM) where buffer 3705 * exhaustion occurs without sleeping for buffer 3706 * reclaimation. This just sticks in a loop and 3707 * constantly attempts to allocate a buffer, which 3708 * hits exhaustion and tries to wakeup bufdaemon. 3709 * This never happens because we never yield. 3710 * 3711 * The real solution is to identify and fix these cases 3712 * so we aren't effectively busy-waiting in a loop 3713 * until the reclaimation path has cycles to run. 3714 */ 3715 kern_yield(PRI_USER); 3716 goto loop; 3717 } 3718 3719 /* 3720 * This code is used to make sure that a buffer is not 3721 * created while the getnewbuf routine is blocked. 3722 * This can be a problem whether the vnode is locked or not. 3723 * If the buffer is created out from under us, we have to 3724 * throw away the one we just created. 3725 * 3726 * Note: this must occur before we associate the buffer 3727 * with the vp especially considering limitations in 3728 * the splay tree implementation when dealing with duplicate 3729 * lblkno's. 3730 */ 3731 BO_LOCK(bo); 3732 if (gbincore(bo, blkno)) { 3733 BO_UNLOCK(bo); 3734 bp->b_flags |= B_INVAL; 3735 brelse(bp); 3736 bufspace_release(maxsize); 3737 goto loop; 3738 } 3739 3740 /* 3741 * Insert the buffer into the hash, so that it can 3742 * be found by incore. 3743 */ 3744 bp->b_blkno = bp->b_lblkno = blkno; 3745 bp->b_offset = offset; 3746 bgetvp(vp, bp); 3747 BO_UNLOCK(bo); 3748 3749 /* 3750 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 3751 * buffer size starts out as 0, B_CACHE will be set by 3752 * allocbuf() for the VMIO case prior to it testing the 3753 * backing store for validity. 3754 */ 3755 3756 if (vmio) { 3757 bp->b_flags |= B_VMIO; 3758 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 3759 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 3760 bp, vp->v_object, bp->b_bufobj->bo_object)); 3761 } else { 3762 bp->b_flags &= ~B_VMIO; 3763 KASSERT(bp->b_bufobj->bo_object == NULL, 3764 ("ARGH! has b_bufobj->bo_object %p %p\n", 3765 bp, bp->b_bufobj->bo_object)); 3766 BUF_CHECK_MAPPED(bp); 3767 } 3768 3769 allocbuf(bp, size); 3770 bufspace_release(maxsize); 3771 bp->b_flags &= ~B_DONE; 3772 } 3773 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 3774 BUF_ASSERT_HELD(bp); 3775end: 3776 KASSERT(bp->b_bufobj == bo, 3777 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 3778 return (bp); 3779} 3780 3781/* 3782 * Get an empty, disassociated buffer of given size. The buffer is initially 3783 * set to B_INVAL. 3784 */ 3785struct buf * 3786geteblk(int size, int flags) 3787{ 3788 struct buf *bp; 3789 int maxsize; 3790 3791 maxsize = (size + BKVAMASK) & ~BKVAMASK; 3792 while ((bp = getnewbuf(NULL, 0, 0, maxsize, flags)) == NULL) { 3793 if ((flags & GB_NOWAIT_BD) && 3794 (curthread->td_pflags & TDP_BUFNEED) != 0) 3795 return (NULL); 3796 } 3797 allocbuf(bp, size); 3798 bufspace_release(maxsize); 3799 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 3800 BUF_ASSERT_HELD(bp); 3801 return (bp); 3802} 3803 3804/* 3805 * Truncate the backing store for a non-vmio buffer. 3806 */ 3807static void 3808vfs_nonvmio_truncate(struct buf *bp, int newbsize) 3809{ 3810 3811 if (bp->b_flags & B_MALLOC) { 3812 /* 3813 * malloced buffers are not shrunk 3814 */ 3815 if (newbsize == 0) { 3816 bufmallocadjust(bp, 0); 3817 free(bp->b_data, M_BIOBUF); 3818 bp->b_data = bp->b_kvabase; 3819 bp->b_flags &= ~B_MALLOC; 3820 } 3821 return; 3822 } 3823 vm_hold_free_pages(bp, newbsize); 3824 bufspace_adjust(bp, newbsize); 3825} 3826 3827/* 3828 * Extend the backing for a non-VMIO buffer. 3829 */ 3830static void 3831vfs_nonvmio_extend(struct buf *bp, int newbsize) 3832{ 3833 caddr_t origbuf; 3834 int origbufsize; 3835 3836 /* 3837 * We only use malloced memory on the first allocation. 3838 * and revert to page-allocated memory when the buffer 3839 * grows. 3840 * 3841 * There is a potential smp race here that could lead 3842 * to bufmallocspace slightly passing the max. It 3843 * is probably extremely rare and not worth worrying 3844 * over. 3845 */ 3846 if (bp->b_bufsize == 0 && newbsize <= PAGE_SIZE/2 && 3847 bufmallocspace < maxbufmallocspace) { 3848 bp->b_data = malloc(newbsize, M_BIOBUF, M_WAITOK); 3849 bp->b_flags |= B_MALLOC; 3850 bufmallocadjust(bp, newbsize); 3851 return; 3852 } 3853 3854 /* 3855 * If the buffer is growing on its other-than-first 3856 * allocation then we revert to the page-allocation 3857 * scheme. 3858 */ 3859 origbuf = NULL; 3860 origbufsize = 0; 3861 if (bp->b_flags & B_MALLOC) { 3862 origbuf = bp->b_data; 3863 origbufsize = bp->b_bufsize; 3864 bp->b_data = bp->b_kvabase; 3865 bufmallocadjust(bp, 0); 3866 bp->b_flags &= ~B_MALLOC; 3867 newbsize = round_page(newbsize); 3868 } 3869 vm_hold_load_pages(bp, (vm_offset_t) bp->b_data + bp->b_bufsize, 3870 (vm_offset_t) bp->b_data + newbsize); 3871 if (origbuf != NULL) { 3872 bcopy(origbuf, bp->b_data, origbufsize); 3873 free(origbuf, M_BIOBUF); 3874 } 3875 bufspace_adjust(bp, newbsize); 3876} 3877 3878/* 3879 * This code constitutes the buffer memory from either anonymous system 3880 * memory (in the case of non-VMIO operations) or from an associated 3881 * VM object (in the case of VMIO operations). This code is able to 3882 * resize a buffer up or down. 3883 * 3884 * Note that this code is tricky, and has many complications to resolve 3885 * deadlock or inconsistent data situations. Tread lightly!!! 3886 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 3887 * the caller. Calling this code willy nilly can result in the loss of data. 3888 * 3889 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 3890 * B_CACHE for the non-VMIO case. 3891 */ 3892int 3893allocbuf(struct buf *bp, int size) 3894{ 3895 int newbsize; 3896 3897 BUF_ASSERT_HELD(bp); 3898 3899 if (bp->b_bcount == size) 3900 return (1); 3901 3902 if (bp->b_kvasize != 0 && bp->b_kvasize < size) 3903 panic("allocbuf: buffer too small"); 3904 3905 newbsize = roundup2(size, DEV_BSIZE); 3906 if ((bp->b_flags & B_VMIO) == 0) { 3907 if ((bp->b_flags & B_MALLOC) == 0) 3908 newbsize = round_page(newbsize); 3909 /* 3910 * Just get anonymous memory from the kernel. Don't 3911 * mess with B_CACHE. 3912 */ 3913 if (newbsize < bp->b_bufsize) 3914 vfs_nonvmio_truncate(bp, newbsize); 3915 else if (newbsize > bp->b_bufsize) 3916 vfs_nonvmio_extend(bp, newbsize); 3917 } else { 3918 int desiredpages; 3919 3920 desiredpages = (size == 0) ? 0 : 3921 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 3922 3923 if (bp->b_flags & B_MALLOC) 3924 panic("allocbuf: VMIO buffer can't be malloced"); 3925 /* 3926 * Set B_CACHE initially if buffer is 0 length or will become 3927 * 0-length. 3928 */ 3929 if (size == 0 || bp->b_bufsize == 0) 3930 bp->b_flags |= B_CACHE; 3931 3932 if (newbsize < bp->b_bufsize) 3933 vfs_vmio_truncate(bp, desiredpages); 3934 /* XXX This looks as if it should be newbsize > b_bufsize */ 3935 else if (size > bp->b_bcount) 3936 vfs_vmio_extend(bp, desiredpages, size); 3937 bufspace_adjust(bp, newbsize); 3938 } 3939 bp->b_bcount = size; /* requested buffer size. */ 3940 return (1); 3941} 3942 3943extern int inflight_transient_maps; 3944 3945static struct bio_queue nondump_bios; 3946 3947void 3948biodone(struct bio *bp) 3949{ 3950 struct mtx *mtxp; 3951 void (*done)(struct bio *); 3952 vm_offset_t start, end; 3953 3954 3955 /* 3956 * Avoid completing I/O when dumping after a panic since that may 3957 * result in a deadlock in the filesystem or pager code. Note that 3958 * this doesn't affect dumps that were started manually since we aim 3959 * to keep the system usable after it has been resumed. 3960 */ 3961 if (__predict_false(dumping && SCHEDULER_STOPPED())) { 3962 TAILQ_INSERT_HEAD(&nondump_bios, bp, bio_queue); 3963 return; 3964 } 3965 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) { 3966 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING; 3967 bp->bio_flags |= BIO_UNMAPPED; 3968 start = trunc_page((vm_offset_t)bp->bio_data); 3969 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length); 3970 bp->bio_data = unmapped_buf; 3971 pmap_qremove(start, atop(end - start)); 3972 vmem_free(transient_arena, start, end - start); 3973 atomic_add_int(&inflight_transient_maps, -1); 3974 } 3975 done = bp->bio_done; 3976 if (done == NULL) { 3977 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3978 mtx_lock(mtxp); 3979 bp->bio_flags |= BIO_DONE; 3980 wakeup(bp); 3981 mtx_unlock(mtxp); 3982 } else 3983 done(bp); 3984} 3985 3986/* 3987 * Wait for a BIO to finish. 3988 */ 3989int 3990biowait(struct bio *bp, const char *wchan) 3991{ 3992 struct mtx *mtxp; 3993 3994 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3995 mtx_lock(mtxp); 3996 while ((bp->bio_flags & BIO_DONE) == 0) 3997 msleep(bp, mtxp, PRIBIO, wchan, 0); 3998 mtx_unlock(mtxp); 3999 if (bp->bio_error != 0) 4000 return (bp->bio_error); 4001 if (!(bp->bio_flags & BIO_ERROR)) 4002 return (0); 4003 return (EIO); 4004} 4005 4006void 4007biofinish(struct bio *bp, struct devstat *stat, int error) 4008{ 4009 4010 if (error) { 4011 bp->bio_error = error; 4012 bp->bio_flags |= BIO_ERROR; 4013 } 4014 if (stat != NULL) 4015 devstat_end_transaction_bio(stat, bp); 4016 biodone(bp); 4017} 4018 4019/* 4020 * bufwait: 4021 * 4022 * Wait for buffer I/O completion, returning error status. The buffer 4023 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 4024 * error and cleared. 4025 */ 4026int 4027bufwait(struct buf *bp) 4028{ 4029 if (bp->b_iocmd == BIO_READ) 4030 bwait(bp, PRIBIO, "biord"); 4031 else 4032 bwait(bp, PRIBIO, "biowr"); 4033 if (bp->b_flags & B_EINTR) { 4034 bp->b_flags &= ~B_EINTR; 4035 return (EINTR); 4036 } 4037 if (bp->b_ioflags & BIO_ERROR) { 4038 return (bp->b_error ? bp->b_error : EIO); 4039 } else { 4040 return (0); 4041 } 4042} 4043 4044/* 4045 * bufdone: 4046 * 4047 * Finish I/O on a buffer, optionally calling a completion function. 4048 * This is usually called from an interrupt so process blocking is 4049 * not allowed. 4050 * 4051 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 4052 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 4053 * assuming B_INVAL is clear. 4054 * 4055 * For the VMIO case, we set B_CACHE if the op was a read and no 4056 * read error occurred, or if the op was a write. B_CACHE is never 4057 * set if the buffer is invalid or otherwise uncacheable. 4058 * 4059 * bufdone does not mess with B_INVAL, allowing the I/O routine or the 4060 * initiator to leave B_INVAL set to brelse the buffer out of existence 4061 * in the biodone routine. 4062 */ 4063void 4064bufdone(struct buf *bp) 4065{ 4066 struct bufobj *dropobj; 4067 void (*biodone)(struct buf *); 4068 4069 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 4070 dropobj = NULL; 4071 4072 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 4073 BUF_ASSERT_HELD(bp); 4074 4075 runningbufwakeup(bp); 4076 if (bp->b_iocmd == BIO_WRITE) 4077 dropobj = bp->b_bufobj; 4078 /* call optional completion function if requested */ 4079 if (bp->b_iodone != NULL) { 4080 biodone = bp->b_iodone; 4081 bp->b_iodone = NULL; 4082 (*biodone) (bp); 4083 if (dropobj) 4084 bufobj_wdrop(dropobj); 4085 return; 4086 } 4087 4088 bufdone_finish(bp); 4089 4090 if (dropobj) 4091 bufobj_wdrop(dropobj); 4092} 4093 4094void 4095bufdone_finish(struct buf *bp) 4096{ 4097 BUF_ASSERT_HELD(bp); 4098 4099 if (!LIST_EMPTY(&bp->b_dep)) 4100 buf_complete(bp); 4101 4102 if (bp->b_flags & B_VMIO) { 4103 /* 4104 * Set B_CACHE if the op was a normal read and no error 4105 * occurred. B_CACHE is set for writes in the b*write() 4106 * routines. 4107 */ 4108 if (bp->b_iocmd == BIO_READ && 4109 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 4110 !(bp->b_ioflags & BIO_ERROR)) 4111 bp->b_flags |= B_CACHE; 4112 vfs_vmio_iodone(bp); 4113 } 4114 4115 /* 4116 * For asynchronous completions, release the buffer now. The brelse 4117 * will do a wakeup there if necessary - so no need to do a wakeup 4118 * here in the async case. The sync case always needs to do a wakeup. 4119 */ 4120 if (bp->b_flags & B_ASYNC) { 4121 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || 4122 (bp->b_ioflags & BIO_ERROR)) 4123 brelse(bp); 4124 else 4125 bqrelse(bp); 4126 } else 4127 bdone(bp); 4128} 4129 4130/* 4131 * This routine is called in lieu of iodone in the case of 4132 * incomplete I/O. This keeps the busy status for pages 4133 * consistent. 4134 */ 4135void 4136vfs_unbusy_pages(struct buf *bp) 4137{ 4138 int i; 4139 vm_object_t obj; 4140 vm_page_t m; 4141 4142 runningbufwakeup(bp); 4143 if (!(bp->b_flags & B_VMIO)) 4144 return; 4145 4146 obj = bp->b_bufobj->bo_object; 4147 VM_OBJECT_WLOCK(obj); 4148 for (i = 0; i < bp->b_npages; i++) { 4149 m = bp->b_pages[i]; 4150 if (m == bogus_page) { 4151 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 4152 if (!m) 4153 panic("vfs_unbusy_pages: page missing\n"); 4154 bp->b_pages[i] = m; 4155 if (buf_mapped(bp)) { 4156 BUF_CHECK_MAPPED(bp); 4157 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4158 bp->b_pages, bp->b_npages); 4159 } else 4160 BUF_CHECK_UNMAPPED(bp); 4161 } 4162 vm_page_sunbusy(m); 4163 } 4164 vm_object_pip_wakeupn(obj, bp->b_npages); 4165 VM_OBJECT_WUNLOCK(obj); 4166} 4167 4168/* 4169 * vfs_page_set_valid: 4170 * 4171 * Set the valid bits in a page based on the supplied offset. The 4172 * range is restricted to the buffer's size. 4173 * 4174 * This routine is typically called after a read completes. 4175 */ 4176static void 4177vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4178{ 4179 vm_ooffset_t eoff; 4180 4181 /* 4182 * Compute the end offset, eoff, such that [off, eoff) does not span a 4183 * page boundary and eoff is not greater than the end of the buffer. 4184 * The end of the buffer, in this case, is our file EOF, not the 4185 * allocation size of the buffer. 4186 */ 4187 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 4188 if (eoff > bp->b_offset + bp->b_bcount) 4189 eoff = bp->b_offset + bp->b_bcount; 4190 4191 /* 4192 * Set valid range. This is typically the entire buffer and thus the 4193 * entire page. 4194 */ 4195 if (eoff > off) 4196 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off); 4197} 4198 4199/* 4200 * vfs_page_set_validclean: 4201 * 4202 * Set the valid bits and clear the dirty bits in a page based on the 4203 * supplied offset. The range is restricted to the buffer's size. 4204 */ 4205static void 4206vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4207{ 4208 vm_ooffset_t soff, eoff; 4209 4210 /* 4211 * Start and end offsets in buffer. eoff - soff may not cross a 4212 * page boundary or cross the end of the buffer. The end of the 4213 * buffer, in this case, is our file EOF, not the allocation size 4214 * of the buffer. 4215 */ 4216 soff = off; 4217 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4218 if (eoff > bp->b_offset + bp->b_bcount) 4219 eoff = bp->b_offset + bp->b_bcount; 4220 4221 /* 4222 * Set valid range. This is typically the entire buffer and thus the 4223 * entire page. 4224 */ 4225 if (eoff > soff) { 4226 vm_page_set_validclean( 4227 m, 4228 (vm_offset_t) (soff & PAGE_MASK), 4229 (vm_offset_t) (eoff - soff) 4230 ); 4231 } 4232} 4233 4234/* 4235 * Ensure that all buffer pages are not exclusive busied. If any page is 4236 * exclusive busy, drain it. 4237 */ 4238void 4239vfs_drain_busy_pages(struct buf *bp) 4240{ 4241 vm_page_t m; 4242 int i, last_busied; 4243 4244 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object); 4245 last_busied = 0; 4246 for (i = 0; i < bp->b_npages; i++) { 4247 m = bp->b_pages[i]; 4248 if (vm_page_xbusied(m)) { 4249 for (; last_busied < i; last_busied++) 4250 vm_page_sbusy(bp->b_pages[last_busied]); 4251 while (vm_page_xbusied(m)) { 4252 vm_page_lock(m); 4253 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4254 vm_page_busy_sleep(m, "vbpage", true); 4255 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4256 } 4257 } 4258 } 4259 for (i = 0; i < last_busied; i++) 4260 vm_page_sunbusy(bp->b_pages[i]); 4261} 4262 4263/* 4264 * This routine is called before a device strategy routine. 4265 * It is used to tell the VM system that paging I/O is in 4266 * progress, and treat the pages associated with the buffer 4267 * almost as being exclusive busy. Also the object paging_in_progress 4268 * flag is handled to make sure that the object doesn't become 4269 * inconsistent. 4270 * 4271 * Since I/O has not been initiated yet, certain buffer flags 4272 * such as BIO_ERROR or B_INVAL may be in an inconsistent state 4273 * and should be ignored. 4274 */ 4275void 4276vfs_busy_pages(struct buf *bp, int clear_modify) 4277{ 4278 vm_object_t obj; 4279 vm_ooffset_t foff; 4280 vm_page_t m; 4281 int i; 4282 bool bogus; 4283 4284 if (!(bp->b_flags & B_VMIO)) 4285 return; 4286 4287 obj = bp->b_bufobj->bo_object; 4288 foff = bp->b_offset; 4289 KASSERT(bp->b_offset != NOOFFSET, 4290 ("vfs_busy_pages: no buffer offset")); 4291 VM_OBJECT_WLOCK(obj); 4292 vfs_drain_busy_pages(bp); 4293 if (bp->b_bufsize != 0) 4294 vfs_setdirty_locked_object(bp); 4295 bogus = false; 4296 for (i = 0; i < bp->b_npages; i++) { 4297 m = bp->b_pages[i]; 4298 4299 if ((bp->b_flags & B_CLUSTER) == 0) { 4300 vm_object_pip_add(obj, 1); 4301 vm_page_sbusy(m); 4302 } 4303 /* 4304 * When readying a buffer for a read ( i.e 4305 * clear_modify == 0 ), it is important to do 4306 * bogus_page replacement for valid pages in 4307 * partially instantiated buffers. Partially 4308 * instantiated buffers can, in turn, occur when 4309 * reconstituting a buffer from its VM backing store 4310 * base. We only have to do this if B_CACHE is 4311 * clear ( which causes the I/O to occur in the 4312 * first place ). The replacement prevents the read 4313 * I/O from overwriting potentially dirty VM-backed 4314 * pages. XXX bogus page replacement is, uh, bogus. 4315 * It may not work properly with small-block devices. 4316 * We need to find a better way. 4317 */ 4318 if (clear_modify) { 4319 pmap_remove_write(m); 4320 vfs_page_set_validclean(bp, foff, m); 4321 } else if (m->valid == VM_PAGE_BITS_ALL && 4322 (bp->b_flags & B_CACHE) == 0) { 4323 bp->b_pages[i] = bogus_page; 4324 bogus = true; 4325 } 4326 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4327 } 4328 VM_OBJECT_WUNLOCK(obj); 4329 if (bogus && buf_mapped(bp)) { 4330 BUF_CHECK_MAPPED(bp); 4331 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4332 bp->b_pages, bp->b_npages); 4333 } 4334} 4335 4336/* 4337 * vfs_bio_set_valid: 4338 * 4339 * Set the range within the buffer to valid. The range is 4340 * relative to the beginning of the buffer, b_offset. Note that 4341 * b_offset itself may be offset from the beginning of the first 4342 * page. 4343 */ 4344void 4345vfs_bio_set_valid(struct buf *bp, int base, int size) 4346{ 4347 int i, n; 4348 vm_page_t m; 4349 4350 if (!(bp->b_flags & B_VMIO)) 4351 return; 4352 4353 /* 4354 * Fixup base to be relative to beginning of first page. 4355 * Set initial n to be the maximum number of bytes in the 4356 * first page that can be validated. 4357 */ 4358 base += (bp->b_offset & PAGE_MASK); 4359 n = PAGE_SIZE - (base & PAGE_MASK); 4360 4361 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4362 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4363 m = bp->b_pages[i]; 4364 if (n > size) 4365 n = size; 4366 vm_page_set_valid_range(m, base & PAGE_MASK, n); 4367 base += n; 4368 size -= n; 4369 n = PAGE_SIZE; 4370 } 4371 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4372} 4373 4374/* 4375 * vfs_bio_clrbuf: 4376 * 4377 * If the specified buffer is a non-VMIO buffer, clear the entire 4378 * buffer. If the specified buffer is a VMIO buffer, clear and 4379 * validate only the previously invalid portions of the buffer. 4380 * This routine essentially fakes an I/O, so we need to clear 4381 * BIO_ERROR and B_INVAL. 4382 * 4383 * Note that while we only theoretically need to clear through b_bcount, 4384 * we go ahead and clear through b_bufsize. 4385 */ 4386void 4387vfs_bio_clrbuf(struct buf *bp) 4388{ 4389 int i, j, mask, sa, ea, slide; 4390 4391 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 4392 clrbuf(bp); 4393 return; 4394 } 4395 bp->b_flags &= ~B_INVAL; 4396 bp->b_ioflags &= ~BIO_ERROR; 4397 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4398 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 4399 (bp->b_offset & PAGE_MASK) == 0) { 4400 if (bp->b_pages[0] == bogus_page) 4401 goto unlock; 4402 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 4403 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object); 4404 if ((bp->b_pages[0]->valid & mask) == mask) 4405 goto unlock; 4406 if ((bp->b_pages[0]->valid & mask) == 0) { 4407 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize); 4408 bp->b_pages[0]->valid |= mask; 4409 goto unlock; 4410 } 4411 } 4412 sa = bp->b_offset & PAGE_MASK; 4413 slide = 0; 4414 for (i = 0; i < bp->b_npages; i++, sa = 0) { 4415 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize); 4416 ea = slide & PAGE_MASK; 4417 if (ea == 0) 4418 ea = PAGE_SIZE; 4419 if (bp->b_pages[i] == bogus_page) 4420 continue; 4421 j = sa / DEV_BSIZE; 4422 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 4423 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object); 4424 if ((bp->b_pages[i]->valid & mask) == mask) 4425 continue; 4426 if ((bp->b_pages[i]->valid & mask) == 0) 4427 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa); 4428 else { 4429 for (; sa < ea; sa += DEV_BSIZE, j++) { 4430 if ((bp->b_pages[i]->valid & (1 << j)) == 0) { 4431 pmap_zero_page_area(bp->b_pages[i], 4432 sa, DEV_BSIZE); 4433 } 4434 } 4435 } 4436 bp->b_pages[i]->valid |= mask; 4437 } 4438unlock: 4439 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4440 bp->b_resid = 0; 4441} 4442 4443void 4444vfs_bio_bzero_buf(struct buf *bp, int base, int size) 4445{ 4446 vm_page_t m; 4447 int i, n; 4448 4449 if (buf_mapped(bp)) { 4450 BUF_CHECK_MAPPED(bp); 4451 bzero(bp->b_data + base, size); 4452 } else { 4453 BUF_CHECK_UNMAPPED(bp); 4454 n = PAGE_SIZE - (base & PAGE_MASK); 4455 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4456 m = bp->b_pages[i]; 4457 if (n > size) 4458 n = size; 4459 pmap_zero_page_area(m, base & PAGE_MASK, n); 4460 base += n; 4461 size -= n; 4462 n = PAGE_SIZE; 4463 } 4464 } 4465} 4466 4467/* 4468 * Update buffer flags based on I/O request parameters, optionally releasing the 4469 * buffer. If it's VMIO or direct I/O, the buffer pages are released to the VM, 4470 * where they may be placed on a page queue (VMIO) or freed immediately (direct 4471 * I/O). Otherwise the buffer is released to the cache. 4472 */ 4473static void 4474b_io_dismiss(struct buf *bp, int ioflag, bool release) 4475{ 4476 4477 KASSERT((ioflag & IO_NOREUSE) == 0 || (ioflag & IO_VMIO) != 0, 4478 ("buf %p non-VMIO noreuse", bp)); 4479 4480 if ((ioflag & IO_DIRECT) != 0) 4481 bp->b_flags |= B_DIRECT; 4482 if ((ioflag & IO_EXT) != 0) 4483 bp->b_xflags |= BX_ALTDATA; 4484 if ((ioflag & (IO_VMIO | IO_DIRECT)) != 0 && LIST_EMPTY(&bp->b_dep)) { 4485 bp->b_flags |= B_RELBUF; 4486 if ((ioflag & IO_NOREUSE) != 0) 4487 bp->b_flags |= B_NOREUSE; 4488 if (release) 4489 brelse(bp); 4490 } else if (release) 4491 bqrelse(bp); 4492} 4493 4494void 4495vfs_bio_brelse(struct buf *bp, int ioflag) 4496{ 4497 4498 b_io_dismiss(bp, ioflag, true); 4499} 4500 4501void 4502vfs_bio_set_flags(struct buf *bp, int ioflag) 4503{ 4504 4505 b_io_dismiss(bp, ioflag, false); 4506} 4507 4508/* 4509 * vm_hold_load_pages and vm_hold_free_pages get pages into 4510 * a buffers address space. The pages are anonymous and are 4511 * not associated with a file object. 4512 */ 4513static void 4514vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4515{ 4516 vm_offset_t pg; 4517 vm_page_t p; 4518 int index; 4519 4520 BUF_CHECK_MAPPED(bp); 4521 4522 to = round_page(to); 4523 from = round_page(from); 4524 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4525 4526 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 4527 /* 4528 * note: must allocate system pages since blocking here 4529 * could interfere with paging I/O, no matter which 4530 * process we are. 4531 */ 4532 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ | 4533 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT) | 4534 VM_ALLOC_WAITOK); 4535 pmap_qenter(pg, &p, 1); 4536 bp->b_pages[index] = p; 4537 } 4538 bp->b_npages = index; 4539} 4540 4541/* Return pages associated with this buf to the vm system */ 4542static void 4543vm_hold_free_pages(struct buf *bp, int newbsize) 4544{ 4545 vm_offset_t from; 4546 vm_page_t p; 4547 int index, newnpages; 4548 4549 BUF_CHECK_MAPPED(bp); 4550 4551 from = round_page((vm_offset_t)bp->b_data + newbsize); 4552 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4553 if (bp->b_npages > newnpages) 4554 pmap_qremove(from, bp->b_npages - newnpages); 4555 for (index = newnpages; index < bp->b_npages; index++) { 4556 p = bp->b_pages[index]; 4557 bp->b_pages[index] = NULL; 4558 p->wire_count--; 4559 vm_page_free(p); 4560 } 4561 atomic_subtract_int(&vm_cnt.v_wire_count, bp->b_npages - newnpages); 4562 bp->b_npages = newnpages; 4563} 4564 4565/* 4566 * Map an IO request into kernel virtual address space. 4567 * 4568 * All requests are (re)mapped into kernel VA space. 4569 * Notice that we use b_bufsize for the size of the buffer 4570 * to be mapped. b_bcount might be modified by the driver. 4571 * 4572 * Note that even if the caller determines that the address space should 4573 * be valid, a race or a smaller-file mapped into a larger space may 4574 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 4575 * check the return value. 4576 * 4577 * This function only works with pager buffers. 4578 */ 4579int 4580vmapbuf(struct buf *bp, void *uaddr, size_t len, int mapbuf) 4581{ 4582 vm_prot_t prot; 4583 int pidx; 4584 4585 prot = VM_PROT_READ; 4586 if (bp->b_iocmd == BIO_READ) 4587 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 4588 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 4589 (vm_offset_t)uaddr, len, prot, bp->b_pages, 4590 btoc(MAXPHYS))) < 0) 4591 return (-1); 4592 bp->b_bufsize = len; 4593 bp->b_npages = pidx; 4594 bp->b_offset = ((vm_offset_t)uaddr) & PAGE_MASK; 4595 if (mapbuf || !unmapped_buf_allowed) { 4596 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_pages, pidx); 4597 bp->b_data = bp->b_kvabase + bp->b_offset; 4598 } else 4599 bp->b_data = unmapped_buf; 4600 return(0); 4601} 4602 4603/* 4604 * Free the io map PTEs associated with this IO operation. 4605 * We also invalidate the TLB entries and restore the original b_addr. 4606 * 4607 * This function only works with pager buffers. 4608 */ 4609void 4610vunmapbuf(struct buf *bp) 4611{ 4612 int npages; 4613 4614 npages = bp->b_npages; 4615 if (buf_mapped(bp)) 4616 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 4617 vm_page_unhold_pages(bp->b_pages, npages); 4618 4619 bp->b_data = unmapped_buf; 4620} 4621 4622void 4623bdone(struct buf *bp) 4624{ 4625 struct mtx *mtxp; 4626 4627 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4628 mtx_lock(mtxp); 4629 bp->b_flags |= B_DONE; 4630 wakeup(bp); 4631 mtx_unlock(mtxp); 4632} 4633 4634void 4635bwait(struct buf *bp, u_char pri, const char *wchan) 4636{ 4637 struct mtx *mtxp; 4638 4639 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4640 mtx_lock(mtxp); 4641 while ((bp->b_flags & B_DONE) == 0) 4642 msleep(bp, mtxp, pri, wchan, 0); 4643 mtx_unlock(mtxp); 4644} 4645 4646int 4647bufsync(struct bufobj *bo, int waitfor) 4648{ 4649 4650 return (VOP_FSYNC(bo->__bo_vnode, waitfor, curthread)); 4651} 4652 4653void 4654bufstrategy(struct bufobj *bo, struct buf *bp) 4655{ 4656 int i = 0; 4657 struct vnode *vp; 4658 4659 vp = bp->b_vp; 4660 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 4661 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 4662 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 4663 i = VOP_STRATEGY(vp, bp); 4664 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 4665} 4666 4667void 4668bufobj_wrefl(struct bufobj *bo) 4669{ 4670 4671 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4672 ASSERT_BO_WLOCKED(bo); 4673 bo->bo_numoutput++; 4674} 4675 4676void 4677bufobj_wref(struct bufobj *bo) 4678{ 4679 4680 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4681 BO_LOCK(bo); 4682 bo->bo_numoutput++; 4683 BO_UNLOCK(bo); 4684} 4685 4686void 4687bufobj_wdrop(struct bufobj *bo) 4688{ 4689 4690 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 4691 BO_LOCK(bo); 4692 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 4693 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 4694 bo->bo_flag &= ~BO_WWAIT; 4695 wakeup(&bo->bo_numoutput); 4696 } 4697 BO_UNLOCK(bo); 4698} 4699 4700int 4701bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 4702{ 4703 int error; 4704 4705 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 4706 ASSERT_BO_WLOCKED(bo); 4707 error = 0; 4708 while (bo->bo_numoutput) { 4709 bo->bo_flag |= BO_WWAIT; 4710 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo), 4711 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 4712 if (error) 4713 break; 4714 } 4715 return (error); 4716} 4717 4718void 4719bpin(struct buf *bp) 4720{ 4721 struct mtx *mtxp; 4722 4723 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4724 mtx_lock(mtxp); 4725 bp->b_pin_count++; 4726 mtx_unlock(mtxp); 4727} 4728 4729void 4730bunpin(struct buf *bp) 4731{ 4732 struct mtx *mtxp; 4733 4734 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4735 mtx_lock(mtxp); 4736 if (--bp->b_pin_count == 0) 4737 wakeup(bp); 4738 mtx_unlock(mtxp); 4739} 4740 4741void 4742bunpin_wait(struct buf *bp) 4743{ 4744 struct mtx *mtxp; 4745 4746 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4747 mtx_lock(mtxp); 4748 while (bp->b_pin_count > 0) 4749 msleep(bp, mtxp, PRIBIO, "bwunpin", 0); 4750 mtx_unlock(mtxp); 4751} 4752 4753/* 4754 * Set bio_data or bio_ma for struct bio from the struct buf. 4755 */ 4756void 4757bdata2bio(struct buf *bp, struct bio *bip) 4758{ 4759 4760 if (!buf_mapped(bp)) { 4761 KASSERT(unmapped_buf_allowed, ("unmapped")); 4762 bip->bio_ma = bp->b_pages; 4763 bip->bio_ma_n = bp->b_npages; 4764 bip->bio_data = unmapped_buf; 4765 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 4766 bip->bio_flags |= BIO_UNMAPPED; 4767 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) / 4768 PAGE_SIZE == bp->b_npages, 4769 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset, 4770 (long long)bip->bio_length, bip->bio_ma_n)); 4771 } else { 4772 bip->bio_data = bp->b_data; 4773 bip->bio_ma = NULL; 4774 } 4775} 4776 4777static int buf_pager_relbuf; 4778SYSCTL_INT(_vfs, OID_AUTO, buf_pager_relbuf, CTLFLAG_RWTUN, 4779 &buf_pager_relbuf, 0, 4780 "Make buffer pager release buffers after reading"); 4781 4782/* 4783 * The buffer pager. It uses buffer reads to validate pages. 4784 * 4785 * In contrast to the generic local pager from vm/vnode_pager.c, this 4786 * pager correctly and easily handles volumes where the underlying 4787 * device block size is greater than the machine page size. The 4788 * buffer cache transparently extends the requested page run to be 4789 * aligned at the block boundary, and does the necessary bogus page 4790 * replacements in the addends to avoid obliterating already valid 4791 * pages. 4792 * 4793 * The only non-trivial issue is that the exclusive busy state for 4794 * pages, which is assumed by the vm_pager_getpages() interface, is 4795 * incompatible with the VMIO buffer cache's desire to share-busy the 4796 * pages. This function performs a trivial downgrade of the pages' 4797 * state before reading buffers, and a less trivial upgrade from the 4798 * shared-busy to excl-busy state after the read. 4799 */ 4800int 4801vfs_bio_getpages(struct vnode *vp, vm_page_t *ma, int count, 4802 int *rbehind, int *rahead, vbg_get_lblkno_t get_lblkno, 4803 vbg_get_blksize_t get_blksize) 4804{ 4805 vm_page_t m; 4806 vm_object_t object; 4807 struct buf *bp; 4808 struct mount *mp; 4809 daddr_t lbn, lbnp; 4810 vm_ooffset_t la, lb, poff, poffe; 4811 long bsize; 4812 int bo_bs, br_flags, error, i, pgsin, pgsin_a, pgsin_b; 4813 bool redo, lpart; 4814 4815 object = vp->v_object; 4816 mp = vp->v_mount; 4817 la = IDX_TO_OFF(ma[count - 1]->pindex); 4818 if (la >= object->un_pager.vnp.vnp_size) 4819 return (VM_PAGER_BAD); 4820 4821 /* 4822 * Change the meaning of la from where the last requested page starts 4823 * to where it ends, because that's the end of the requested region 4824 * and the start of the potential read-ahead region. 4825 */ 4826 la += PAGE_SIZE; 4827 lpart = la > object->un_pager.vnp.vnp_size; 4828 bo_bs = get_blksize(vp, get_lblkno(vp, IDX_TO_OFF(ma[0]->pindex))); 4829 4830 /* 4831 * Calculate read-ahead, behind and total pages. 4832 */ 4833 pgsin = count; 4834 lb = IDX_TO_OFF(ma[0]->pindex); 4835 pgsin_b = OFF_TO_IDX(lb - rounddown2(lb, bo_bs)); 4836 pgsin += pgsin_b; 4837 if (rbehind != NULL) 4838 *rbehind = pgsin_b; 4839 pgsin_a = OFF_TO_IDX(roundup2(la, bo_bs) - la); 4840 if (la + IDX_TO_OFF(pgsin_a) >= object->un_pager.vnp.vnp_size) 4841 pgsin_a = OFF_TO_IDX(roundup2(object->un_pager.vnp.vnp_size, 4842 PAGE_SIZE) - la); 4843 pgsin += pgsin_a; 4844 if (rahead != NULL) 4845 *rahead = pgsin_a; 4846 PCPU_INC(cnt.v_vnodein); 4847 PCPU_ADD(cnt.v_vnodepgsin, pgsin); 4848 4849 br_flags = (mp != NULL && (mp->mnt_kern_flag & MNTK_UNMAPPED_BUFS) 4850 != 0) ? GB_UNMAPPED : 0; 4851 VM_OBJECT_WLOCK(object); 4852again: 4853 for (i = 0; i < count; i++) 4854 vm_page_busy_downgrade(ma[i]); 4855 VM_OBJECT_WUNLOCK(object); 4856 4857 lbnp = -1; 4858 for (i = 0; i < count; i++) { 4859 m = ma[i]; 4860 4861 /* 4862 * Pages are shared busy and the object lock is not 4863 * owned, which together allow for the pages' 4864 * invalidation. The racy test for validity avoids 4865 * useless creation of the buffer for the most typical 4866 * case when invalidation is not used in redo or for 4867 * parallel read. The shared->excl upgrade loop at 4868 * the end of the function catches the race in a 4869 * reliable way (protected by the object lock). 4870 */ 4871 if (m->valid == VM_PAGE_BITS_ALL) 4872 continue; 4873 4874 poff = IDX_TO_OFF(m->pindex); 4875 poffe = MIN(poff + PAGE_SIZE, object->un_pager.vnp.vnp_size); 4876 for (; poff < poffe; poff += bsize) { 4877 lbn = get_lblkno(vp, poff); 4878 if (lbn == lbnp) 4879 goto next_page; 4880 lbnp = lbn; 4881 4882 bsize = get_blksize(vp, lbn); 4883 error = bread_gb(vp, lbn, bsize, curthread->td_ucred, 4884 br_flags, &bp); 4885 if (error != 0) 4886 goto end_pages; 4887 if (LIST_EMPTY(&bp->b_dep)) { 4888 /* 4889 * Invalidation clears m->valid, but 4890 * may leave B_CACHE flag if the 4891 * buffer existed at the invalidation 4892 * time. In this case, recycle the 4893 * buffer to do real read on next 4894 * bread() after redo. 4895 * 4896 * Otherwise B_RELBUF is not strictly 4897 * necessary, enable to reduce buf 4898 * cache pressure. 4899 */ 4900 if (buf_pager_relbuf || 4901 m->valid != VM_PAGE_BITS_ALL) 4902 bp->b_flags |= B_RELBUF; 4903 4904 bp->b_flags &= ~B_NOCACHE; 4905 brelse(bp); 4906 } else { 4907 bqrelse(bp); 4908 } 4909 } 4910 KASSERT(1 /* racy, enable for debugging */ || 4911 m->valid == VM_PAGE_BITS_ALL || i == count - 1, 4912 ("buf %d %p invalid", i, m)); 4913 if (i == count - 1 && lpart) { 4914 VM_OBJECT_WLOCK(object); 4915 if (m->valid != 0 && 4916 m->valid != VM_PAGE_BITS_ALL) 4917 vm_page_zero_invalid(m, TRUE); 4918 VM_OBJECT_WUNLOCK(object); 4919 } 4920next_page:; 4921 } 4922end_pages: 4923 4924 VM_OBJECT_WLOCK(object); 4925 redo = false; 4926 for (i = 0; i < count; i++) { 4927 vm_page_sunbusy(ma[i]); 4928 ma[i] = vm_page_grab(object, ma[i]->pindex, VM_ALLOC_NORMAL); 4929 4930 /* 4931 * Since the pages were only sbusy while neither the 4932 * buffer nor the object lock was held by us, or 4933 * reallocated while vm_page_grab() slept for busy 4934 * relinguish, they could have been invalidated. 4935 * Recheck the valid bits and re-read as needed. 4936 * 4937 * Note that the last page is made fully valid in the 4938 * read loop, and partial validity for the page at 4939 * index count - 1 could mean that the page was 4940 * invalidated or removed, so we must restart for 4941 * safety as well. 4942 */ 4943 if (ma[i]->valid != VM_PAGE_BITS_ALL) 4944 redo = true; 4945 } 4946 if (redo && error == 0) 4947 goto again; 4948 VM_OBJECT_WUNLOCK(object); 4949 return (error != 0 ? VM_PAGER_ERROR : VM_PAGER_OK); 4950} 4951 4952#include "opt_ddb.h" 4953#ifdef DDB 4954#include <ddb/ddb.h> 4955 4956/* DDB command to show buffer data */ 4957DB_SHOW_COMMAND(buffer, db_show_buffer) 4958{ 4959 /* get args */ 4960 struct buf *bp = (struct buf *)addr; 4961 4962 if (!have_addr) { 4963 db_printf("usage: show buffer <addr>\n"); 4964 return; 4965 } 4966 4967 db_printf("buf at %p\n", bp); 4968 db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n", 4969 (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags, 4970 PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS); 4971 db_printf( 4972 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 4973 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, " 4974 "b_dep = %p\n", 4975 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 4976 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 4977 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first); 4978 db_printf("b_kvabase = %p, b_kvasize = %d\n", 4979 bp->b_kvabase, bp->b_kvasize); 4980 if (bp->b_npages) { 4981 int i; 4982 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 4983 for (i = 0; i < bp->b_npages; i++) { 4984 vm_page_t m; 4985 m = bp->b_pages[i]; 4986 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 4987 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 4988 if ((i + 1) < bp->b_npages) 4989 db_printf(","); 4990 } 4991 db_printf("\n"); 4992 } 4993 db_printf(" "); 4994 BUF_LOCKPRINTINFO(bp); 4995} 4996 4997DB_SHOW_COMMAND(lockedbufs, lockedbufs) 4998{ 4999 struct buf *bp; 5000 int i; 5001 5002 for (i = 0; i < nbuf; i++) { 5003 bp = &buf[i]; 5004 if (BUF_ISLOCKED(bp)) { 5005 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 5006 db_printf("\n"); 5007 if (db_pager_quit) 5008 break; 5009 } 5010 } 5011} 5012 5013DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 5014{ 5015 struct vnode *vp; 5016 struct buf *bp; 5017 5018 if (!have_addr) { 5019 db_printf("usage: show vnodebufs <addr>\n"); 5020 return; 5021 } 5022 vp = (struct vnode *)addr; 5023 db_printf("Clean buffers:\n"); 5024 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 5025 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 5026 db_printf("\n"); 5027 } 5028 db_printf("Dirty buffers:\n"); 5029 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 5030 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 5031 db_printf("\n"); 5032 } 5033} 5034 5035DB_COMMAND(countfreebufs, db_coundfreebufs) 5036{ 5037 struct buf *bp; 5038 int i, used = 0, nfree = 0; 5039 5040 if (have_addr) { 5041 db_printf("usage: countfreebufs\n"); 5042 return; 5043 } 5044 5045 for (i = 0; i < nbuf; i++) { 5046 bp = &buf[i]; 5047 if (bp->b_qindex == QUEUE_EMPTY) 5048 nfree++; 5049 else 5050 used++; 5051 } 5052 5053 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 5054 nfree + used); 5055 db_printf("numfreebuffers is %d\n", numfreebuffers); 5056} 5057#endif /* DDB */ 5058