1/*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2004 Poul-Henning Kamp 5 * Copyright (c) 1994,1997 John S. Dyson 6 * Copyright (c) 2013 The FreeBSD Foundation 7 * All rights reserved. 8 * 9 * Portions of this software were developed by Konstantin Belousov 10 * under sponsorship from the FreeBSD Foundation. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34/* 35 * this file contains a new buffer I/O scheme implementing a coherent 36 * VM object and buffer cache scheme. Pains have been taken to make 37 * sure that the performance degradation associated with schemes such 38 * as this is not realized. 39 * 40 * Author: John S. Dyson 41 * Significant help during the development and debugging phases 42 * had been provided by David Greenman, also of the FreeBSD core team. 43 * 44 * see man buf(9) for more info. 45 */ 46 47#include <sys/cdefs.h> 48__FBSDID("$FreeBSD$"); 49 50#include <sys/param.h> 51#include <sys/systm.h> 52#include <sys/bio.h> 53#include <sys/bitset.h> 54#include <sys/conf.h> 55#include <sys/counter.h> 56#include <sys/buf.h> 57#include <sys/devicestat.h> 58#include <sys/eventhandler.h> 59#include <sys/fail.h> 60#include <sys/ktr.h> 61#include <sys/limits.h> 62#include <sys/lock.h> 63#include <sys/malloc.h> 64#include <sys/mount.h> 65#include <sys/mutex.h> 66#include <sys/kernel.h> 67#include <sys/kthread.h> 68#include <sys/proc.h> 69#include <sys/racct.h> 70#include <sys/refcount.h> 71#include <sys/resourcevar.h> 72#include <sys/rwlock.h> 73#include <sys/smp.h> 74#include <sys/sysctl.h> 75#include <sys/syscallsubr.h> 76#include <sys/vmem.h> 77#include <sys/vmmeter.h> 78#include <sys/vnode.h> 79#include <sys/watchdog.h> 80#include <geom/geom.h> 81#include <vm/vm.h> 82#include <vm/vm_param.h> 83#include <vm/vm_kern.h> 84#include <vm/vm_object.h> 85#include <vm/vm_page.h> 86#include <vm/vm_pageout.h> 87#include <vm/vm_pager.h> 88#include <vm/vm_extern.h> 89#include <vm/vm_map.h> 90#include <vm/swap_pager.h> 91 92static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer"); 93 94struct bio_ops bioops; /* I/O operation notification */ 95 96struct buf_ops buf_ops_bio = { 97 .bop_name = "buf_ops_bio", 98 .bop_write = bufwrite, 99 .bop_strategy = bufstrategy, 100 .bop_sync = bufsync, 101 .bop_bdflush = bufbdflush, 102}; 103 104struct bufqueue { 105 struct mtx_padalign bq_lock; 106 TAILQ_HEAD(, buf) bq_queue; 107 uint8_t bq_index; 108 uint16_t bq_subqueue; 109 int bq_len; 110} __aligned(CACHE_LINE_SIZE); 111 112#define BQ_LOCKPTR(bq) (&(bq)->bq_lock) 113#define BQ_LOCK(bq) mtx_lock(BQ_LOCKPTR((bq))) 114#define BQ_UNLOCK(bq) mtx_unlock(BQ_LOCKPTR((bq))) 115#define BQ_ASSERT_LOCKED(bq) mtx_assert(BQ_LOCKPTR((bq)), MA_OWNED) 116 117struct bufdomain { 118 struct bufqueue bd_subq[MAXCPU + 1]; /* Per-cpu sub queues + global */ 119 struct bufqueue bd_dirtyq; 120 struct bufqueue *bd_cleanq; 121 struct mtx_padalign bd_run_lock; 122 /* Constants */ 123 long bd_maxbufspace; 124 long bd_hibufspace; 125 long bd_lobufspace; 126 long bd_bufspacethresh; 127 int bd_hifreebuffers; 128 int bd_lofreebuffers; 129 int bd_hidirtybuffers; 130 int bd_lodirtybuffers; 131 int bd_dirtybufthresh; 132 int bd_lim; 133 /* atomics */ 134 int bd_wanted; 135 int __aligned(CACHE_LINE_SIZE) bd_numdirtybuffers; 136 int __aligned(CACHE_LINE_SIZE) bd_running; 137 long __aligned(CACHE_LINE_SIZE) bd_bufspace; 138 int __aligned(CACHE_LINE_SIZE) bd_freebuffers; 139} __aligned(CACHE_LINE_SIZE); 140 141#define BD_LOCKPTR(bd) (&(bd)->bd_cleanq->bq_lock) 142#define BD_LOCK(bd) mtx_lock(BD_LOCKPTR((bd))) 143#define BD_UNLOCK(bd) mtx_unlock(BD_LOCKPTR((bd))) 144#define BD_ASSERT_LOCKED(bd) mtx_assert(BD_LOCKPTR((bd)), MA_OWNED) 145#define BD_RUN_LOCKPTR(bd) (&(bd)->bd_run_lock) 146#define BD_RUN_LOCK(bd) mtx_lock(BD_RUN_LOCKPTR((bd))) 147#define BD_RUN_UNLOCK(bd) mtx_unlock(BD_RUN_LOCKPTR((bd))) 148#define BD_DOMAIN(bd) (bd - bdomain) 149 150static char *buf; /* buffer header pool */ 151static struct buf * 152nbufp(unsigned i) 153{ 154 return ((struct buf *)(buf + (sizeof(struct buf) + 155 sizeof(vm_page_t) * atop(maxbcachebuf)) * i)); 156} 157 158caddr_t __read_mostly unmapped_buf; 159 160/* Used below and for softdep flushing threads in ufs/ffs/ffs_softdep.c */ 161struct proc *bufdaemonproc; 162 163static void vm_hold_free_pages(struct buf *bp, int newbsize); 164static void vm_hold_load_pages(struct buf *bp, vm_offset_t from, 165 vm_offset_t to); 166static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m); 167static void vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, 168 vm_page_t m); 169static void vfs_clean_pages_dirty_buf(struct buf *bp); 170static void vfs_setdirty_range(struct buf *bp); 171static void vfs_vmio_invalidate(struct buf *bp); 172static void vfs_vmio_truncate(struct buf *bp, int npages); 173static void vfs_vmio_extend(struct buf *bp, int npages, int size); 174static int vfs_bio_clcheck(struct vnode *vp, int size, 175 daddr_t lblkno, daddr_t blkno); 176static void breada(struct vnode *, daddr_t *, int *, int, struct ucred *, int, 177 void (*)(struct buf *)); 178static int buf_flush(struct vnode *vp, struct bufdomain *, int); 179static int flushbufqueues(struct vnode *, struct bufdomain *, int, int); 180static void buf_daemon(void); 181static __inline void bd_wakeup(void); 182static int sysctl_runningspace(SYSCTL_HANDLER_ARGS); 183static void bufkva_reclaim(vmem_t *, int); 184static void bufkva_free(struct buf *); 185static int buf_import(void *, void **, int, int, int); 186static void buf_release(void *, void **, int); 187static void maxbcachebuf_adjust(void); 188static inline struct bufdomain *bufdomain(struct buf *); 189static void bq_remove(struct bufqueue *bq, struct buf *bp); 190static void bq_insert(struct bufqueue *bq, struct buf *bp, bool unlock); 191static int buf_recycle(struct bufdomain *, bool kva); 192static void bq_init(struct bufqueue *bq, int qindex, int cpu, 193 const char *lockname); 194static void bd_init(struct bufdomain *bd); 195static int bd_flushall(struct bufdomain *bd); 196static int sysctl_bufdomain_long(SYSCTL_HANDLER_ARGS); 197static int sysctl_bufdomain_int(SYSCTL_HANDLER_ARGS); 198 199static int sysctl_bufspace(SYSCTL_HANDLER_ARGS); 200int vmiodirenable = TRUE; 201SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, 202 "Use the VM system for directory writes"); 203long runningbufspace; 204SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 205 "Amount of presently outstanding async buffer io"); 206SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD, 207 NULL, 0, sysctl_bufspace, "L", "Physical memory used for buffers"); 208static counter_u64_t bufkvaspace; 209SYSCTL_COUNTER_U64(_vfs, OID_AUTO, bufkvaspace, CTLFLAG_RD, &bufkvaspace, 210 "Kernel virtual memory used for buffers"); 211static long maxbufspace; 212SYSCTL_PROC(_vfs, OID_AUTO, maxbufspace, 213 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &maxbufspace, 214 __offsetof(struct bufdomain, bd_maxbufspace), sysctl_bufdomain_long, "L", 215 "Maximum allowed value of bufspace (including metadata)"); 216static long bufmallocspace; 217SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 218 "Amount of malloced memory for buffers"); 219static long maxbufmallocspace; 220SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 221 0, "Maximum amount of malloced memory for buffers"); 222static long lobufspace; 223SYSCTL_PROC(_vfs, OID_AUTO, lobufspace, 224 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &lobufspace, 225 __offsetof(struct bufdomain, bd_lobufspace), sysctl_bufdomain_long, "L", 226 "Minimum amount of buffers we want to have"); 227long hibufspace; 228SYSCTL_PROC(_vfs, OID_AUTO, hibufspace, 229 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &hibufspace, 230 __offsetof(struct bufdomain, bd_hibufspace), sysctl_bufdomain_long, "L", 231 "Maximum allowed value of bufspace (excluding metadata)"); 232long bufspacethresh; 233SYSCTL_PROC(_vfs, OID_AUTO, bufspacethresh, 234 CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RW, &bufspacethresh, 235 __offsetof(struct bufdomain, bd_bufspacethresh), sysctl_bufdomain_long, "L", 236 "Bufspace consumed before waking the daemon to free some"); 237static counter_u64_t buffreekvacnt; 238SYSCTL_COUNTER_U64(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 239 "Number of times we have freed the KVA space from some buffer"); 240static counter_u64_t bufdefragcnt; 241SYSCTL_COUNTER_U64(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 242 "Number of times we have had to repeat buffer allocation to defragment"); 243static long lorunningspace; 244SYSCTL_PROC(_vfs, OID_AUTO, lorunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE | 245 CTLFLAG_RW, &lorunningspace, 0, sysctl_runningspace, "L", 246 "Minimum preferred space used for in-progress I/O"); 247static long hirunningspace; 248SYSCTL_PROC(_vfs, OID_AUTO, hirunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE | 249 CTLFLAG_RW, &hirunningspace, 0, sysctl_runningspace, "L", 250 "Maximum amount of space to use for in-progress I/O"); 251int dirtybufferflushes; 252SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes, 253 0, "Number of bdwrite to bawrite conversions to limit dirty buffers"); 254int bdwriteskip; 255SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip, 256 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk"); 257int altbufferflushes; 258SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW | CTLFLAG_STATS, 259 &altbufferflushes, 0, "Number of fsync flushes to limit dirty buffers"); 260static int recursiveflushes; 261SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW | CTLFLAG_STATS, 262 &recursiveflushes, 0, "Number of flushes skipped due to being recursive"); 263static int sysctl_numdirtybuffers(SYSCTL_HANDLER_ARGS); 264SYSCTL_PROC(_vfs, OID_AUTO, numdirtybuffers, 265 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RD, NULL, 0, sysctl_numdirtybuffers, "I", 266 "Number of buffers that are dirty (has unwritten changes) at the moment"); 267static int lodirtybuffers; 268SYSCTL_PROC(_vfs, OID_AUTO, lodirtybuffers, 269 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &lodirtybuffers, 270 __offsetof(struct bufdomain, bd_lodirtybuffers), sysctl_bufdomain_int, "I", 271 "How many buffers we want to have free before bufdaemon can sleep"); 272static int hidirtybuffers; 273SYSCTL_PROC(_vfs, OID_AUTO, hidirtybuffers, 274 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &hidirtybuffers, 275 __offsetof(struct bufdomain, bd_hidirtybuffers), sysctl_bufdomain_int, "I", 276 "When the number of dirty buffers is considered severe"); 277int dirtybufthresh; 278SYSCTL_PROC(_vfs, OID_AUTO, dirtybufthresh, 279 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &dirtybufthresh, 280 __offsetof(struct bufdomain, bd_dirtybufthresh), sysctl_bufdomain_int, "I", 281 "Number of bdwrite to bawrite conversions to clear dirty buffers"); 282static int numfreebuffers; 283SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, 284 "Number of free buffers"); 285static int lofreebuffers; 286SYSCTL_PROC(_vfs, OID_AUTO, lofreebuffers, 287 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &lofreebuffers, 288 __offsetof(struct bufdomain, bd_lofreebuffers), sysctl_bufdomain_int, "I", 289 "Target number of free buffers"); 290static int hifreebuffers; 291SYSCTL_PROC(_vfs, OID_AUTO, hifreebuffers, 292 CTLTYPE_INT|CTLFLAG_MPSAFE|CTLFLAG_RW, &hifreebuffers, 293 __offsetof(struct bufdomain, bd_hifreebuffers), sysctl_bufdomain_int, "I", 294 "Threshold for clean buffer recycling"); 295static counter_u64_t getnewbufcalls; 296SYSCTL_COUNTER_U64(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RD, 297 &getnewbufcalls, "Number of calls to getnewbuf"); 298static counter_u64_t getnewbufrestarts; 299SYSCTL_COUNTER_U64(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RD, 300 &getnewbufrestarts, 301 "Number of times getnewbuf has had to restart a buffer acquisition"); 302static counter_u64_t mappingrestarts; 303SYSCTL_COUNTER_U64(_vfs, OID_AUTO, mappingrestarts, CTLFLAG_RD, 304 &mappingrestarts, 305 "Number of times getblk has had to restart a buffer mapping for " 306 "unmapped buffer"); 307static counter_u64_t numbufallocfails; 308SYSCTL_COUNTER_U64(_vfs, OID_AUTO, numbufallocfails, CTLFLAG_RW, 309 &numbufallocfails, "Number of times buffer allocations failed"); 310static int flushbufqtarget = 100; 311SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0, 312 "Amount of work to do in flushbufqueues when helping bufdaemon"); 313static counter_u64_t notbufdflushes; 314SYSCTL_COUNTER_U64(_vfs, OID_AUTO, notbufdflushes, CTLFLAG_RD, ¬bufdflushes, 315 "Number of dirty buffer flushes done by the bufdaemon helpers"); 316static long barrierwrites; 317SYSCTL_LONG(_vfs, OID_AUTO, barrierwrites, CTLFLAG_RW | CTLFLAG_STATS, 318 &barrierwrites, 0, "Number of barrier writes"); 319SYSCTL_INT(_vfs, OID_AUTO, unmapped_buf_allowed, CTLFLAG_RD, 320 &unmapped_buf_allowed, 0, 321 "Permit the use of the unmapped i/o"); 322int maxbcachebuf = MAXBCACHEBUF; 323SYSCTL_INT(_vfs, OID_AUTO, maxbcachebuf, CTLFLAG_RDTUN, &maxbcachebuf, 0, 324 "Maximum size of a buffer cache block"); 325 326/* 327 * This lock synchronizes access to bd_request. 328 */ 329static struct mtx_padalign __exclusive_cache_line bdlock; 330 331/* 332 * This lock protects the runningbufreq and synchronizes runningbufwakeup and 333 * waitrunningbufspace(). 334 */ 335static struct mtx_padalign __exclusive_cache_line rbreqlock; 336 337/* 338 * Lock that protects bdirtywait. 339 */ 340static struct mtx_padalign __exclusive_cache_line bdirtylock; 341 342/* 343 * Wakeup point for bufdaemon, as well as indicator of whether it is already 344 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it 345 * is idling. 346 */ 347static int bd_request; 348 349/* 350 * Request for the buf daemon to write more buffers than is indicated by 351 * lodirtybuf. This may be necessary to push out excess dependencies or 352 * defragment the address space where a simple count of the number of dirty 353 * buffers is insufficient to characterize the demand for flushing them. 354 */ 355static int bd_speedupreq; 356 357/* 358 * Synchronization (sleep/wakeup) variable for active buffer space requests. 359 * Set when wait starts, cleared prior to wakeup(). 360 * Used in runningbufwakeup() and waitrunningbufspace(). 361 */ 362static int runningbufreq; 363 364/* 365 * Synchronization for bwillwrite() waiters. 366 */ 367static int bdirtywait; 368 369/* 370 * Definitions for the buffer free lists. 371 */ 372#define QUEUE_NONE 0 /* on no queue */ 373#define QUEUE_EMPTY 1 /* empty buffer headers */ 374#define QUEUE_DIRTY 2 /* B_DELWRI buffers */ 375#define QUEUE_CLEAN 3 /* non-B_DELWRI buffers */ 376#define QUEUE_SENTINEL 4 /* not an queue index, but mark for sentinel */ 377 378/* Maximum number of buffer domains. */ 379#define BUF_DOMAINS 8 380 381struct bufdomainset bdlodirty; /* Domains > lodirty */ 382struct bufdomainset bdhidirty; /* Domains > hidirty */ 383 384/* Configured number of clean queues. */ 385static int __read_mostly buf_domains; 386 387BITSET_DEFINE(bufdomainset, BUF_DOMAINS); 388struct bufdomain __exclusive_cache_line bdomain[BUF_DOMAINS]; 389struct bufqueue __exclusive_cache_line bqempty; 390 391/* 392 * per-cpu empty buffer cache. 393 */ 394uma_zone_t buf_zone; 395 396/* 397 * Single global constant for BUF_WMESG, to avoid getting multiple references. 398 * buf_wmesg is referred from macros. 399 */ 400const char *buf_wmesg = BUF_WMESG; 401 402static int 403sysctl_runningspace(SYSCTL_HANDLER_ARGS) 404{ 405 long value; 406 int error; 407 408 value = *(long *)arg1; 409 error = sysctl_handle_long(oidp, &value, 0, req); 410 if (error != 0 || req->newptr == NULL) 411 return (error); 412 mtx_lock(&rbreqlock); 413 if (arg1 == &hirunningspace) { 414 if (value < lorunningspace) 415 error = EINVAL; 416 else 417 hirunningspace = value; 418 } else { 419 KASSERT(arg1 == &lorunningspace, 420 ("%s: unknown arg1", __func__)); 421 if (value > hirunningspace) 422 error = EINVAL; 423 else 424 lorunningspace = value; 425 } 426 mtx_unlock(&rbreqlock); 427 return (error); 428} 429 430static int 431sysctl_bufdomain_int(SYSCTL_HANDLER_ARGS) 432{ 433 int error; 434 int value; 435 int i; 436 437 value = *(int *)arg1; 438 error = sysctl_handle_int(oidp, &value, 0, req); 439 if (error != 0 || req->newptr == NULL) 440 return (error); 441 *(int *)arg1 = value; 442 for (i = 0; i < buf_domains; i++) 443 *(int *)(uintptr_t)(((uintptr_t)&bdomain[i]) + arg2) = 444 value / buf_domains; 445 446 return (error); 447} 448 449static int 450sysctl_bufdomain_long(SYSCTL_HANDLER_ARGS) 451{ 452 long value; 453 int error; 454 int i; 455 456 value = *(long *)arg1; 457 error = sysctl_handle_long(oidp, &value, 0, req); 458 if (error != 0 || req->newptr == NULL) 459 return (error); 460 *(long *)arg1 = value; 461 for (i = 0; i < buf_domains; i++) 462 *(long *)(uintptr_t)(((uintptr_t)&bdomain[i]) + arg2) = 463 value / buf_domains; 464 465 return (error); 466} 467 468#if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 469 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 470static int 471sysctl_bufspace(SYSCTL_HANDLER_ARGS) 472{ 473 long lvalue; 474 int ivalue; 475 int i; 476 477 lvalue = 0; 478 for (i = 0; i < buf_domains; i++) 479 lvalue += bdomain[i].bd_bufspace; 480 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long)) 481 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 482 if (lvalue > INT_MAX) 483 /* On overflow, still write out a long to trigger ENOMEM. */ 484 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 485 ivalue = lvalue; 486 return (sysctl_handle_int(oidp, &ivalue, 0, req)); 487} 488#else 489static int 490sysctl_bufspace(SYSCTL_HANDLER_ARGS) 491{ 492 long lvalue; 493 int i; 494 495 lvalue = 0; 496 for (i = 0; i < buf_domains; i++) 497 lvalue += bdomain[i].bd_bufspace; 498 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 499} 500#endif 501 502static int 503sysctl_numdirtybuffers(SYSCTL_HANDLER_ARGS) 504{ 505 int value; 506 int i; 507 508 value = 0; 509 for (i = 0; i < buf_domains; i++) 510 value += bdomain[i].bd_numdirtybuffers; 511 return (sysctl_handle_int(oidp, &value, 0, req)); 512} 513 514/* 515 * bdirtywakeup: 516 * 517 * Wakeup any bwillwrite() waiters. 518 */ 519static void 520bdirtywakeup(void) 521{ 522 mtx_lock(&bdirtylock); 523 if (bdirtywait) { 524 bdirtywait = 0; 525 wakeup(&bdirtywait); 526 } 527 mtx_unlock(&bdirtylock); 528} 529 530/* 531 * bd_clear: 532 * 533 * Clear a domain from the appropriate bitsets when dirtybuffers 534 * is decremented. 535 */ 536static void 537bd_clear(struct bufdomain *bd) 538{ 539 540 mtx_lock(&bdirtylock); 541 if (bd->bd_numdirtybuffers <= bd->bd_lodirtybuffers) 542 BIT_CLR(BUF_DOMAINS, BD_DOMAIN(bd), &bdlodirty); 543 if (bd->bd_numdirtybuffers <= bd->bd_hidirtybuffers) 544 BIT_CLR(BUF_DOMAINS, BD_DOMAIN(bd), &bdhidirty); 545 mtx_unlock(&bdirtylock); 546} 547 548/* 549 * bd_set: 550 * 551 * Set a domain in the appropriate bitsets when dirtybuffers 552 * is incremented. 553 */ 554static void 555bd_set(struct bufdomain *bd) 556{ 557 558 mtx_lock(&bdirtylock); 559 if (bd->bd_numdirtybuffers > bd->bd_lodirtybuffers) 560 BIT_SET(BUF_DOMAINS, BD_DOMAIN(bd), &bdlodirty); 561 if (bd->bd_numdirtybuffers > bd->bd_hidirtybuffers) 562 BIT_SET(BUF_DOMAINS, BD_DOMAIN(bd), &bdhidirty); 563 mtx_unlock(&bdirtylock); 564} 565 566/* 567 * bdirtysub: 568 * 569 * Decrement the numdirtybuffers count by one and wakeup any 570 * threads blocked in bwillwrite(). 571 */ 572static void 573bdirtysub(struct buf *bp) 574{ 575 struct bufdomain *bd; 576 int num; 577 578 bd = bufdomain(bp); 579 num = atomic_fetchadd_int(&bd->bd_numdirtybuffers, -1); 580 if (num == (bd->bd_lodirtybuffers + bd->bd_hidirtybuffers) / 2) 581 bdirtywakeup(); 582 if (num == bd->bd_lodirtybuffers || num == bd->bd_hidirtybuffers) 583 bd_clear(bd); 584} 585 586/* 587 * bdirtyadd: 588 * 589 * Increment the numdirtybuffers count by one and wakeup the buf 590 * daemon if needed. 591 */ 592static void 593bdirtyadd(struct buf *bp) 594{ 595 struct bufdomain *bd; 596 int num; 597 598 /* 599 * Only do the wakeup once as we cross the boundary. The 600 * buf daemon will keep running until the condition clears. 601 */ 602 bd = bufdomain(bp); 603 num = atomic_fetchadd_int(&bd->bd_numdirtybuffers, 1); 604 if (num == (bd->bd_lodirtybuffers + bd->bd_hidirtybuffers) / 2) 605 bd_wakeup(); 606 if (num == bd->bd_lodirtybuffers || num == bd->bd_hidirtybuffers) 607 bd_set(bd); 608} 609 610/* 611 * bufspace_daemon_wakeup: 612 * 613 * Wakeup the daemons responsible for freeing clean bufs. 614 */ 615static void 616bufspace_daemon_wakeup(struct bufdomain *bd) 617{ 618 619 /* 620 * avoid the lock if the daemon is running. 621 */ 622 if (atomic_fetchadd_int(&bd->bd_running, 1) == 0) { 623 BD_RUN_LOCK(bd); 624 atomic_store_int(&bd->bd_running, 1); 625 wakeup(&bd->bd_running); 626 BD_RUN_UNLOCK(bd); 627 } 628} 629 630/* 631 * bufspace_daemon_wait: 632 * 633 * Sleep until the domain falls below a limit or one second passes. 634 */ 635static void 636bufspace_daemon_wait(struct bufdomain *bd) 637{ 638 /* 639 * Re-check our limits and sleep. bd_running must be 640 * cleared prior to checking the limits to avoid missed 641 * wakeups. The waker will adjust one of bufspace or 642 * freebuffers prior to checking bd_running. 643 */ 644 BD_RUN_LOCK(bd); 645 atomic_store_int(&bd->bd_running, 0); 646 if (bd->bd_bufspace < bd->bd_bufspacethresh && 647 bd->bd_freebuffers > bd->bd_lofreebuffers) { 648 msleep(&bd->bd_running, BD_RUN_LOCKPTR(bd), PRIBIO|PDROP, 649 "-", hz); 650 } else { 651 /* Avoid spurious wakeups while running. */ 652 atomic_store_int(&bd->bd_running, 1); 653 BD_RUN_UNLOCK(bd); 654 } 655} 656 657/* 658 * bufspace_adjust: 659 * 660 * Adjust the reported bufspace for a KVA managed buffer, possibly 661 * waking any waiters. 662 */ 663static void 664bufspace_adjust(struct buf *bp, int bufsize) 665{ 666 struct bufdomain *bd; 667 long space; 668 int diff; 669 670 KASSERT((bp->b_flags & B_MALLOC) == 0, 671 ("bufspace_adjust: malloc buf %p", bp)); 672 bd = bufdomain(bp); 673 diff = bufsize - bp->b_bufsize; 674 if (diff < 0) { 675 atomic_subtract_long(&bd->bd_bufspace, -diff); 676 } else if (diff > 0) { 677 space = atomic_fetchadd_long(&bd->bd_bufspace, diff); 678 /* Wake up the daemon on the transition. */ 679 if (space < bd->bd_bufspacethresh && 680 space + diff >= bd->bd_bufspacethresh) 681 bufspace_daemon_wakeup(bd); 682 } 683 bp->b_bufsize = bufsize; 684} 685 686/* 687 * bufspace_reserve: 688 * 689 * Reserve bufspace before calling allocbuf(). metadata has a 690 * different space limit than data. 691 */ 692static int 693bufspace_reserve(struct bufdomain *bd, int size, bool metadata) 694{ 695 long limit, new; 696 long space; 697 698 if (metadata) 699 limit = bd->bd_maxbufspace; 700 else 701 limit = bd->bd_hibufspace; 702 space = atomic_fetchadd_long(&bd->bd_bufspace, size); 703 new = space + size; 704 if (new > limit) { 705 atomic_subtract_long(&bd->bd_bufspace, size); 706 return (ENOSPC); 707 } 708 709 /* Wake up the daemon on the transition. */ 710 if (space < bd->bd_bufspacethresh && new >= bd->bd_bufspacethresh) 711 bufspace_daemon_wakeup(bd); 712 713 return (0); 714} 715 716/* 717 * bufspace_release: 718 * 719 * Release reserved bufspace after bufspace_adjust() has consumed it. 720 */ 721static void 722bufspace_release(struct bufdomain *bd, int size) 723{ 724 725 atomic_subtract_long(&bd->bd_bufspace, size); 726} 727 728/* 729 * bufspace_wait: 730 * 731 * Wait for bufspace, acting as the buf daemon if a locked vnode is 732 * supplied. bd_wanted must be set prior to polling for space. The 733 * operation must be re-tried on return. 734 */ 735static void 736bufspace_wait(struct bufdomain *bd, struct vnode *vp, int gbflags, 737 int slpflag, int slptimeo) 738{ 739 struct thread *td; 740 int error, fl, norunbuf; 741 742 if ((gbflags & GB_NOWAIT_BD) != 0) 743 return; 744 745 td = curthread; 746 BD_LOCK(bd); 747 while (bd->bd_wanted) { 748 if (vp != NULL && vp->v_type != VCHR && 749 (td->td_pflags & TDP_BUFNEED) == 0) { 750 BD_UNLOCK(bd); 751 /* 752 * getblk() is called with a vnode locked, and 753 * some majority of the dirty buffers may as 754 * well belong to the vnode. Flushing the 755 * buffers there would make a progress that 756 * cannot be achieved by the buf_daemon, that 757 * cannot lock the vnode. 758 */ 759 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) | 760 (td->td_pflags & TDP_NORUNNINGBUF); 761 762 /* 763 * Play bufdaemon. The getnewbuf() function 764 * may be called while the thread owns lock 765 * for another dirty buffer for the same 766 * vnode, which makes it impossible to use 767 * VOP_FSYNC() there, due to the buffer lock 768 * recursion. 769 */ 770 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF; 771 fl = buf_flush(vp, bd, flushbufqtarget); 772 td->td_pflags &= norunbuf; 773 BD_LOCK(bd); 774 if (fl != 0) 775 continue; 776 if (bd->bd_wanted == 0) 777 break; 778 } 779 error = msleep(&bd->bd_wanted, BD_LOCKPTR(bd), 780 (PRIBIO + 4) | slpflag, "newbuf", slptimeo); 781 if (error != 0) 782 break; 783 } 784 BD_UNLOCK(bd); 785} 786 787/* 788 * bufspace_daemon: 789 * 790 * buffer space management daemon. Tries to maintain some marginal 791 * amount of free buffer space so that requesting processes neither 792 * block nor work to reclaim buffers. 793 */ 794static void 795bufspace_daemon(void *arg) 796{ 797 struct bufdomain *bd; 798 799 EVENTHANDLER_REGISTER(shutdown_pre_sync, kthread_shutdown, curthread, 800 SHUTDOWN_PRI_LAST + 100); 801 802 bd = arg; 803 for (;;) { 804 kthread_suspend_check(); 805 806 /* 807 * Free buffers from the clean queue until we meet our 808 * targets. 809 * 810 * Theory of operation: The buffer cache is most efficient 811 * when some free buffer headers and space are always 812 * available to getnewbuf(). This daemon attempts to prevent 813 * the excessive blocking and synchronization associated 814 * with shortfall. It goes through three phases according 815 * demand: 816 * 817 * 1) The daemon wakes up voluntarily once per-second 818 * during idle periods when the counters are below 819 * the wakeup thresholds (bufspacethresh, lofreebuffers). 820 * 821 * 2) The daemon wakes up as we cross the thresholds 822 * ahead of any potential blocking. This may bounce 823 * slightly according to the rate of consumption and 824 * release. 825 * 826 * 3) The daemon and consumers are starved for working 827 * clean buffers. This is the 'bufspace' sleep below 828 * which will inefficiently trade bufs with bqrelse 829 * until we return to condition 2. 830 */ 831 while (bd->bd_bufspace > bd->bd_lobufspace || 832 bd->bd_freebuffers < bd->bd_hifreebuffers) { 833 if (buf_recycle(bd, false) != 0) { 834 if (bd_flushall(bd)) 835 continue; 836 /* 837 * Speedup dirty if we've run out of clean 838 * buffers. This is possible in particular 839 * because softdep may held many bufs locked 840 * pending writes to other bufs which are 841 * marked for delayed write, exhausting 842 * clean space until they are written. 843 */ 844 bd_speedup(); 845 BD_LOCK(bd); 846 if (bd->bd_wanted) { 847 msleep(&bd->bd_wanted, BD_LOCKPTR(bd), 848 PRIBIO|PDROP, "bufspace", hz/10); 849 } else 850 BD_UNLOCK(bd); 851 } 852 maybe_yield(); 853 } 854 bufspace_daemon_wait(bd); 855 } 856} 857 858/* 859 * bufmallocadjust: 860 * 861 * Adjust the reported bufspace for a malloc managed buffer, possibly 862 * waking any waiters. 863 */ 864static void 865bufmallocadjust(struct buf *bp, int bufsize) 866{ 867 int diff; 868 869 KASSERT((bp->b_flags & B_MALLOC) != 0, 870 ("bufmallocadjust: non-malloc buf %p", bp)); 871 diff = bufsize - bp->b_bufsize; 872 if (diff < 0) 873 atomic_subtract_long(&bufmallocspace, -diff); 874 else 875 atomic_add_long(&bufmallocspace, diff); 876 bp->b_bufsize = bufsize; 877} 878 879/* 880 * runningwakeup: 881 * 882 * Wake up processes that are waiting on asynchronous writes to fall 883 * below lorunningspace. 884 */ 885static void 886runningwakeup(void) 887{ 888 889 mtx_lock(&rbreqlock); 890 if (runningbufreq) { 891 runningbufreq = 0; 892 wakeup(&runningbufreq); 893 } 894 mtx_unlock(&rbreqlock); 895} 896 897/* 898 * runningbufwakeup: 899 * 900 * Decrement the outstanding write count according. 901 */ 902void 903runningbufwakeup(struct buf *bp) 904{ 905 long space, bspace; 906 907 bspace = bp->b_runningbufspace; 908 if (bspace == 0) 909 return; 910 space = atomic_fetchadd_long(&runningbufspace, -bspace); 911 KASSERT(space >= bspace, ("runningbufspace underflow %ld %ld", 912 space, bspace)); 913 bp->b_runningbufspace = 0; 914 /* 915 * Only acquire the lock and wakeup on the transition from exceeding 916 * the threshold to falling below it. 917 */ 918 if (space < lorunningspace) 919 return; 920 if (space - bspace > lorunningspace) 921 return; 922 runningwakeup(); 923} 924 925/* 926 * waitrunningbufspace() 927 * 928 * runningbufspace is a measure of the amount of I/O currently 929 * running. This routine is used in async-write situations to 930 * prevent creating huge backups of pending writes to a device. 931 * Only asynchronous writes are governed by this function. 932 * 933 * This does NOT turn an async write into a sync write. It waits 934 * for earlier writes to complete and generally returns before the 935 * caller's write has reached the device. 936 */ 937void 938waitrunningbufspace(void) 939{ 940 941 mtx_lock(&rbreqlock); 942 while (runningbufspace > hirunningspace) { 943 runningbufreq = 1; 944 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 945 } 946 mtx_unlock(&rbreqlock); 947} 948 949/* 950 * vfs_buf_test_cache: 951 * 952 * Called when a buffer is extended. This function clears the B_CACHE 953 * bit if the newly extended portion of the buffer does not contain 954 * valid data. 955 */ 956static __inline void 957vfs_buf_test_cache(struct buf *bp, vm_ooffset_t foff, vm_offset_t off, 958 vm_offset_t size, vm_page_t m) 959{ 960 961 /* 962 * This function and its results are protected by higher level 963 * synchronization requiring vnode and buf locks to page in and 964 * validate pages. 965 */ 966 if (bp->b_flags & B_CACHE) { 967 int base = (foff + off) & PAGE_MASK; 968 if (vm_page_is_valid(m, base, size) == 0) 969 bp->b_flags &= ~B_CACHE; 970 } 971} 972 973/* Wake up the buffer daemon if necessary */ 974static void 975bd_wakeup(void) 976{ 977 978 mtx_lock(&bdlock); 979 if (bd_request == 0) { 980 bd_request = 1; 981 wakeup(&bd_request); 982 } 983 mtx_unlock(&bdlock); 984} 985 986/* 987 * Adjust the maxbcachbuf tunable. 988 */ 989static void 990maxbcachebuf_adjust(void) 991{ 992 int i; 993 994 /* 995 * maxbcachebuf must be a power of 2 >= MAXBSIZE. 996 */ 997 i = 2; 998 while (i * 2 <= maxbcachebuf) 999 i *= 2; 1000 maxbcachebuf = i; 1001 if (maxbcachebuf < MAXBSIZE) 1002 maxbcachebuf = MAXBSIZE; 1003 if (maxbcachebuf > maxphys) 1004 maxbcachebuf = maxphys; 1005 if (bootverbose != 0 && maxbcachebuf != MAXBCACHEBUF) 1006 printf("maxbcachebuf=%d\n", maxbcachebuf); 1007} 1008 1009/* 1010 * bd_speedup - speedup the buffer cache flushing code 1011 */ 1012void 1013bd_speedup(void) 1014{ 1015 int needwake; 1016 1017 mtx_lock(&bdlock); 1018 needwake = 0; 1019 if (bd_speedupreq == 0 || bd_request == 0) 1020 needwake = 1; 1021 bd_speedupreq = 1; 1022 bd_request = 1; 1023 if (needwake) 1024 wakeup(&bd_request); 1025 mtx_unlock(&bdlock); 1026} 1027 1028#ifdef __i386__ 1029#define TRANSIENT_DENOM 5 1030#else 1031#define TRANSIENT_DENOM 10 1032#endif 1033 1034/* 1035 * Calculating buffer cache scaling values and reserve space for buffer 1036 * headers. This is called during low level kernel initialization and 1037 * may be called more then once. We CANNOT write to the memory area 1038 * being reserved at this time. 1039 */ 1040caddr_t 1041kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 1042{ 1043 int tuned_nbuf; 1044 long maxbuf, maxbuf_sz, buf_sz, biotmap_sz; 1045 1046 /* 1047 * physmem_est is in pages. Convert it to kilobytes (assumes 1048 * PAGE_SIZE is >= 1K) 1049 */ 1050 physmem_est = physmem_est * (PAGE_SIZE / 1024); 1051 1052 maxbcachebuf_adjust(); 1053 /* 1054 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 1055 * For the first 64MB of ram nominally allocate sufficient buffers to 1056 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 1057 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing 1058 * the buffer cache we limit the eventual kva reservation to 1059 * maxbcache bytes. 1060 * 1061 * factor represents the 1/4 x ram conversion. 1062 */ 1063 if (nbuf == 0) { 1064 int factor = 4 * BKVASIZE / 1024; 1065 1066 nbuf = 50; 1067 if (physmem_est > 4096) 1068 nbuf += min((physmem_est - 4096) / factor, 1069 65536 / factor); 1070 if (physmem_est > 65536) 1071 nbuf += min((physmem_est - 65536) * 2 / (factor * 5), 1072 32 * 1024 * 1024 / (factor * 5)); 1073 1074 if (maxbcache && nbuf > maxbcache / BKVASIZE) 1075 nbuf = maxbcache / BKVASIZE; 1076 tuned_nbuf = 1; 1077 } else 1078 tuned_nbuf = 0; 1079 1080 /* XXX Avoid unsigned long overflows later on with maxbufspace. */ 1081 maxbuf = (LONG_MAX / 3) / BKVASIZE; 1082 if (nbuf > maxbuf) { 1083 if (!tuned_nbuf) 1084 printf("Warning: nbufs lowered from %d to %ld\n", nbuf, 1085 maxbuf); 1086 nbuf = maxbuf; 1087 } 1088 1089 /* 1090 * Ideal allocation size for the transient bio submap is 10% 1091 * of the maximal space buffer map. This roughly corresponds 1092 * to the amount of the buffer mapped for typical UFS load. 1093 * 1094 * Clip the buffer map to reserve space for the transient 1095 * BIOs, if its extent is bigger than 90% (80% on i386) of the 1096 * maximum buffer map extent on the platform. 1097 * 1098 * The fall-back to the maxbuf in case of maxbcache unset, 1099 * allows to not trim the buffer KVA for the architectures 1100 * with ample KVA space. 1101 */ 1102 if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) { 1103 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE; 1104 buf_sz = (long)nbuf * BKVASIZE; 1105 if (buf_sz < maxbuf_sz / TRANSIENT_DENOM * 1106 (TRANSIENT_DENOM - 1)) { 1107 /* 1108 * There is more KVA than memory. Do not 1109 * adjust buffer map size, and assign the rest 1110 * of maxbuf to transient map. 1111 */ 1112 biotmap_sz = maxbuf_sz - buf_sz; 1113 } else { 1114 /* 1115 * Buffer map spans all KVA we could afford on 1116 * this platform. Give 10% (20% on i386) of 1117 * the buffer map to the transient bio map. 1118 */ 1119 biotmap_sz = buf_sz / TRANSIENT_DENOM; 1120 buf_sz -= biotmap_sz; 1121 } 1122 if (biotmap_sz / INT_MAX > maxphys) 1123 bio_transient_maxcnt = INT_MAX; 1124 else 1125 bio_transient_maxcnt = biotmap_sz / maxphys; 1126 /* 1127 * Artificially limit to 1024 simultaneous in-flight I/Os 1128 * using the transient mapping. 1129 */ 1130 if (bio_transient_maxcnt > 1024) 1131 bio_transient_maxcnt = 1024; 1132 if (tuned_nbuf) 1133 nbuf = buf_sz / BKVASIZE; 1134 } 1135 1136 if (nswbuf == 0) { 1137 nswbuf = min(nbuf / 4, 256); 1138 if (nswbuf < NSWBUF_MIN) 1139 nswbuf = NSWBUF_MIN; 1140 } 1141 1142 /* 1143 * Reserve space for the buffer cache buffers 1144 */ 1145 buf = (char *)v; 1146 v = (caddr_t)buf + (sizeof(struct buf) + sizeof(vm_page_t) * 1147 atop(maxbcachebuf)) * nbuf; 1148 1149 return (v); 1150} 1151 1152/* Initialize the buffer subsystem. Called before use of any buffers. */ 1153void 1154bufinit(void) 1155{ 1156 struct buf *bp; 1157 int i; 1158 1159 KASSERT(maxbcachebuf >= MAXBSIZE, 1160 ("maxbcachebuf (%d) must be >= MAXBSIZE (%d)\n", maxbcachebuf, 1161 MAXBSIZE)); 1162 bq_init(&bqempty, QUEUE_EMPTY, -1, "bufq empty lock"); 1163 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 1164 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 1165 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF); 1166 1167 unmapped_buf = (caddr_t)kva_alloc(maxphys); 1168 1169 /* finally, initialize each buffer header and stick on empty q */ 1170 for (i = 0; i < nbuf; i++) { 1171 bp = nbufp(i); 1172 bzero(bp, sizeof(*bp) + sizeof(vm_page_t) * atop(maxbcachebuf)); 1173 bp->b_flags = B_INVAL; 1174 bp->b_rcred = NOCRED; 1175 bp->b_wcred = NOCRED; 1176 bp->b_qindex = QUEUE_NONE; 1177 bp->b_domain = -1; 1178 bp->b_subqueue = mp_maxid + 1; 1179 bp->b_xflags = 0; 1180 bp->b_data = bp->b_kvabase = unmapped_buf; 1181 LIST_INIT(&bp->b_dep); 1182 BUF_LOCKINIT(bp); 1183 bq_insert(&bqempty, bp, false); 1184 } 1185 1186 /* 1187 * maxbufspace is the absolute maximum amount of buffer space we are 1188 * allowed to reserve in KVM and in real terms. The absolute maximum 1189 * is nominally used by metadata. hibufspace is the nominal maximum 1190 * used by most other requests. The differential is required to 1191 * ensure that metadata deadlocks don't occur. 1192 * 1193 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 1194 * this may result in KVM fragmentation which is not handled optimally 1195 * by the system. XXX This is less true with vmem. We could use 1196 * PAGE_SIZE. 1197 */ 1198 maxbufspace = (long)nbuf * BKVASIZE; 1199 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - maxbcachebuf * 10); 1200 lobufspace = (hibufspace / 20) * 19; /* 95% */ 1201 bufspacethresh = lobufspace + (hibufspace - lobufspace) / 2; 1202 1203 /* 1204 * Note: The 16 MiB upper limit for hirunningspace was chosen 1205 * arbitrarily and may need further tuning. It corresponds to 1206 * 128 outstanding write IO requests (if IO size is 128 KiB), 1207 * which fits with many RAID controllers' tagged queuing limits. 1208 * The lower 1 MiB limit is the historical upper limit for 1209 * hirunningspace. 1210 */ 1211 hirunningspace = lmax(lmin(roundup(hibufspace / 64, maxbcachebuf), 1212 16 * 1024 * 1024), 1024 * 1024); 1213 lorunningspace = roundup((hirunningspace * 2) / 3, maxbcachebuf); 1214 1215 /* 1216 * Limit the amount of malloc memory since it is wired permanently into 1217 * the kernel space. Even though this is accounted for in the buffer 1218 * allocation, we don't want the malloced region to grow uncontrolled. 1219 * The malloc scheme improves memory utilization significantly on 1220 * average (small) directories. 1221 */ 1222 maxbufmallocspace = hibufspace / 20; 1223 1224 /* 1225 * Reduce the chance of a deadlock occurring by limiting the number 1226 * of delayed-write dirty buffers we allow to stack up. 1227 */ 1228 hidirtybuffers = nbuf / 4 + 20; 1229 dirtybufthresh = hidirtybuffers * 9 / 10; 1230 /* 1231 * To support extreme low-memory systems, make sure hidirtybuffers 1232 * cannot eat up all available buffer space. This occurs when our 1233 * minimum cannot be met. We try to size hidirtybuffers to 3/4 our 1234 * buffer space assuming BKVASIZE'd buffers. 1235 */ 1236 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 1237 hidirtybuffers >>= 1; 1238 } 1239 lodirtybuffers = hidirtybuffers / 2; 1240 1241 /* 1242 * lofreebuffers should be sufficient to avoid stalling waiting on 1243 * buf headers under heavy utilization. The bufs in per-cpu caches 1244 * are counted as free but will be unavailable to threads executing 1245 * on other cpus. 1246 * 1247 * hifreebuffers is the free target for the bufspace daemon. This 1248 * should be set appropriately to limit work per-iteration. 1249 */ 1250 lofreebuffers = MIN((nbuf / 25) + (20 * mp_ncpus), 128 * mp_ncpus); 1251 hifreebuffers = (3 * lofreebuffers) / 2; 1252 numfreebuffers = nbuf; 1253 1254 /* Setup the kva and free list allocators. */ 1255 vmem_set_reclaim(buffer_arena, bufkva_reclaim); 1256 buf_zone = uma_zcache_create("buf free cache", 1257 sizeof(struct buf) + sizeof(vm_page_t) * atop(maxbcachebuf), 1258 NULL, NULL, NULL, NULL, buf_import, buf_release, NULL, 0); 1259 1260 /* 1261 * Size the clean queue according to the amount of buffer space. 1262 * One queue per-256mb up to the max. More queues gives better 1263 * concurrency but less accurate LRU. 1264 */ 1265 buf_domains = MIN(howmany(maxbufspace, 256*1024*1024), BUF_DOMAINS); 1266 for (i = 0 ; i < buf_domains; i++) { 1267 struct bufdomain *bd; 1268 1269 bd = &bdomain[i]; 1270 bd_init(bd); 1271 bd->bd_freebuffers = nbuf / buf_domains; 1272 bd->bd_hifreebuffers = hifreebuffers / buf_domains; 1273 bd->bd_lofreebuffers = lofreebuffers / buf_domains; 1274 bd->bd_bufspace = 0; 1275 bd->bd_maxbufspace = maxbufspace / buf_domains; 1276 bd->bd_hibufspace = hibufspace / buf_domains; 1277 bd->bd_lobufspace = lobufspace / buf_domains; 1278 bd->bd_bufspacethresh = bufspacethresh / buf_domains; 1279 bd->bd_numdirtybuffers = 0; 1280 bd->bd_hidirtybuffers = hidirtybuffers / buf_domains; 1281 bd->bd_lodirtybuffers = lodirtybuffers / buf_domains; 1282 bd->bd_dirtybufthresh = dirtybufthresh / buf_domains; 1283 /* Don't allow more than 2% of bufs in the per-cpu caches. */ 1284 bd->bd_lim = nbuf / buf_domains / 50 / mp_ncpus; 1285 } 1286 getnewbufcalls = counter_u64_alloc(M_WAITOK); 1287 getnewbufrestarts = counter_u64_alloc(M_WAITOK); 1288 mappingrestarts = counter_u64_alloc(M_WAITOK); 1289 numbufallocfails = counter_u64_alloc(M_WAITOK); 1290 notbufdflushes = counter_u64_alloc(M_WAITOK); 1291 buffreekvacnt = counter_u64_alloc(M_WAITOK); 1292 bufdefragcnt = counter_u64_alloc(M_WAITOK); 1293 bufkvaspace = counter_u64_alloc(M_WAITOK); 1294} 1295 1296#ifdef INVARIANTS 1297static inline void 1298vfs_buf_check_mapped(struct buf *bp) 1299{ 1300 1301 KASSERT(bp->b_kvabase != unmapped_buf, 1302 ("mapped buf: b_kvabase was not updated %p", bp)); 1303 KASSERT(bp->b_data != unmapped_buf, 1304 ("mapped buf: b_data was not updated %p", bp)); 1305 KASSERT(bp->b_data < unmapped_buf || bp->b_data >= unmapped_buf + 1306 maxphys, ("b_data + b_offset unmapped %p", bp)); 1307} 1308 1309static inline void 1310vfs_buf_check_unmapped(struct buf *bp) 1311{ 1312 1313 KASSERT(bp->b_data == unmapped_buf, 1314 ("unmapped buf: corrupted b_data %p", bp)); 1315} 1316 1317#define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp) 1318#define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp) 1319#else 1320#define BUF_CHECK_MAPPED(bp) do {} while (0) 1321#define BUF_CHECK_UNMAPPED(bp) do {} while (0) 1322#endif 1323 1324static int 1325isbufbusy(struct buf *bp) 1326{ 1327 if (((bp->b_flags & B_INVAL) == 0 && BUF_ISLOCKED(bp)) || 1328 ((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI)) 1329 return (1); 1330 return (0); 1331} 1332 1333/* 1334 * Shutdown the system cleanly to prepare for reboot, halt, or power off. 1335 */ 1336void 1337bufshutdown(int show_busybufs) 1338{ 1339 static int first_buf_printf = 1; 1340 struct buf *bp; 1341 int i, iter, nbusy, pbusy; 1342#ifndef PREEMPTION 1343 int subiter; 1344#endif 1345 1346 /* 1347 * Sync filesystems for shutdown 1348 */ 1349 wdog_kern_pat(WD_LASTVAL); 1350 kern_sync(curthread); 1351 1352 /* 1353 * With soft updates, some buffers that are 1354 * written will be remarked as dirty until other 1355 * buffers are written. 1356 */ 1357 for (iter = pbusy = 0; iter < 20; iter++) { 1358 nbusy = 0; 1359 for (i = nbuf - 1; i >= 0; i--) { 1360 bp = nbufp(i); 1361 if (isbufbusy(bp)) 1362 nbusy++; 1363 } 1364 if (nbusy == 0) { 1365 if (first_buf_printf) 1366 printf("All buffers synced."); 1367 break; 1368 } 1369 if (first_buf_printf) { 1370 printf("Syncing disks, buffers remaining... "); 1371 first_buf_printf = 0; 1372 } 1373 printf("%d ", nbusy); 1374 if (nbusy < pbusy) 1375 iter = 0; 1376 pbusy = nbusy; 1377 1378 wdog_kern_pat(WD_LASTVAL); 1379 kern_sync(curthread); 1380 1381#ifdef PREEMPTION 1382 /* 1383 * Spin for a while to allow interrupt threads to run. 1384 */ 1385 DELAY(50000 * iter); 1386#else 1387 /* 1388 * Context switch several times to allow interrupt 1389 * threads to run. 1390 */ 1391 for (subiter = 0; subiter < 50 * iter; subiter++) { 1392 thread_lock(curthread); 1393 mi_switch(SW_VOL); 1394 DELAY(1000); 1395 } 1396#endif 1397 } 1398 printf("\n"); 1399 /* 1400 * Count only busy local buffers to prevent forcing 1401 * a fsck if we're just a client of a wedged NFS server 1402 */ 1403 nbusy = 0; 1404 for (i = nbuf - 1; i >= 0; i--) { 1405 bp = nbufp(i); 1406 if (isbufbusy(bp)) { 1407#if 0 1408/* XXX: This is bogus. We should probably have a BO_REMOTE flag instead */ 1409 if (bp->b_dev == NULL) { 1410 TAILQ_REMOVE(&mountlist, 1411 bp->b_vp->v_mount, mnt_list); 1412 continue; 1413 } 1414#endif 1415 nbusy++; 1416 if (show_busybufs > 0) { 1417 printf( 1418 "%d: buf:%p, vnode:%p, flags:%0x, blkno:%jd, lblkno:%jd, buflock:", 1419 nbusy, bp, bp->b_vp, bp->b_flags, 1420 (intmax_t)bp->b_blkno, 1421 (intmax_t)bp->b_lblkno); 1422 BUF_LOCKPRINTINFO(bp); 1423 if (show_busybufs > 1) 1424 vn_printf(bp->b_vp, 1425 "vnode content: "); 1426 } 1427 } 1428 } 1429 if (nbusy) { 1430 /* 1431 * Failed to sync all blocks. Indicate this and don't 1432 * unmount filesystems (thus forcing an fsck on reboot). 1433 */ 1434 printf("Giving up on %d buffers\n", nbusy); 1435 DELAY(5000000); /* 5 seconds */ 1436 } else { 1437 if (!first_buf_printf) 1438 printf("Final sync complete\n"); 1439 /* 1440 * Unmount filesystems 1441 */ 1442 if (!KERNEL_PANICKED()) 1443 vfs_unmountall(); 1444 } 1445 swapoff_all(); 1446 DELAY(100000); /* wait for console output to finish */ 1447} 1448 1449static void 1450bpmap_qenter(struct buf *bp) 1451{ 1452 1453 BUF_CHECK_MAPPED(bp); 1454 1455 /* 1456 * bp->b_data is relative to bp->b_offset, but 1457 * bp->b_offset may be offset into the first page. 1458 */ 1459 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data); 1460 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages); 1461 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 1462 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 1463} 1464 1465static inline struct bufdomain * 1466bufdomain(struct buf *bp) 1467{ 1468 1469 return (&bdomain[bp->b_domain]); 1470} 1471 1472static struct bufqueue * 1473bufqueue(struct buf *bp) 1474{ 1475 1476 switch (bp->b_qindex) { 1477 case QUEUE_NONE: 1478 /* FALLTHROUGH */ 1479 case QUEUE_SENTINEL: 1480 return (NULL); 1481 case QUEUE_EMPTY: 1482 return (&bqempty); 1483 case QUEUE_DIRTY: 1484 return (&bufdomain(bp)->bd_dirtyq); 1485 case QUEUE_CLEAN: 1486 return (&bufdomain(bp)->bd_subq[bp->b_subqueue]); 1487 default: 1488 break; 1489 } 1490 panic("bufqueue(%p): Unhandled type %d\n", bp, bp->b_qindex); 1491} 1492 1493/* 1494 * Return the locked bufqueue that bp is a member of. 1495 */ 1496static struct bufqueue * 1497bufqueue_acquire(struct buf *bp) 1498{ 1499 struct bufqueue *bq, *nbq; 1500 1501 /* 1502 * bp can be pushed from a per-cpu queue to the 1503 * cleanq while we're waiting on the lock. Retry 1504 * if the queues don't match. 1505 */ 1506 bq = bufqueue(bp); 1507 BQ_LOCK(bq); 1508 for (;;) { 1509 nbq = bufqueue(bp); 1510 if (bq == nbq) 1511 break; 1512 BQ_UNLOCK(bq); 1513 BQ_LOCK(nbq); 1514 bq = nbq; 1515 } 1516 return (bq); 1517} 1518 1519/* 1520 * binsfree: 1521 * 1522 * Insert the buffer into the appropriate free list. Requires a 1523 * locked buffer on entry and buffer is unlocked before return. 1524 */ 1525static void 1526binsfree(struct buf *bp, int qindex) 1527{ 1528 struct bufdomain *bd; 1529 struct bufqueue *bq; 1530 1531 KASSERT(qindex == QUEUE_CLEAN || qindex == QUEUE_DIRTY, 1532 ("binsfree: Invalid qindex %d", qindex)); 1533 BUF_ASSERT_XLOCKED(bp); 1534 1535 /* 1536 * Handle delayed bremfree() processing. 1537 */ 1538 if (bp->b_flags & B_REMFREE) { 1539 if (bp->b_qindex == qindex) { 1540 bp->b_flags |= B_REUSE; 1541 bp->b_flags &= ~B_REMFREE; 1542 BUF_UNLOCK(bp); 1543 return; 1544 } 1545 bq = bufqueue_acquire(bp); 1546 bq_remove(bq, bp); 1547 BQ_UNLOCK(bq); 1548 } 1549 bd = bufdomain(bp); 1550 if (qindex == QUEUE_CLEAN) { 1551 if (bd->bd_lim != 0) 1552 bq = &bd->bd_subq[PCPU_GET(cpuid)]; 1553 else 1554 bq = bd->bd_cleanq; 1555 } else 1556 bq = &bd->bd_dirtyq; 1557 bq_insert(bq, bp, true); 1558} 1559 1560/* 1561 * buf_free: 1562 * 1563 * Free a buffer to the buf zone once it no longer has valid contents. 1564 */ 1565static void 1566buf_free(struct buf *bp) 1567{ 1568 1569 if (bp->b_flags & B_REMFREE) 1570 bremfreef(bp); 1571 if (bp->b_vflags & BV_BKGRDINPROG) 1572 panic("losing buffer 1"); 1573 if (bp->b_rcred != NOCRED) { 1574 crfree(bp->b_rcred); 1575 bp->b_rcred = NOCRED; 1576 } 1577 if (bp->b_wcred != NOCRED) { 1578 crfree(bp->b_wcred); 1579 bp->b_wcred = NOCRED; 1580 } 1581 if (!LIST_EMPTY(&bp->b_dep)) 1582 buf_deallocate(bp); 1583 bufkva_free(bp); 1584 atomic_add_int(&bufdomain(bp)->bd_freebuffers, 1); 1585 MPASS((bp->b_flags & B_MAXPHYS) == 0); 1586 BUF_UNLOCK(bp); 1587 uma_zfree(buf_zone, bp); 1588} 1589 1590/* 1591 * buf_import: 1592 * 1593 * Import bufs into the uma cache from the buf list. The system still 1594 * expects a static array of bufs and much of the synchronization 1595 * around bufs assumes type stable storage. As a result, UMA is used 1596 * only as a per-cpu cache of bufs still maintained on a global list. 1597 */ 1598static int 1599buf_import(void *arg, void **store, int cnt, int domain, int flags) 1600{ 1601 struct buf *bp; 1602 int i; 1603 1604 BQ_LOCK(&bqempty); 1605 for (i = 0; i < cnt; i++) { 1606 bp = TAILQ_FIRST(&bqempty.bq_queue); 1607 if (bp == NULL) 1608 break; 1609 bq_remove(&bqempty, bp); 1610 store[i] = bp; 1611 } 1612 BQ_UNLOCK(&bqempty); 1613 1614 return (i); 1615} 1616 1617/* 1618 * buf_release: 1619 * 1620 * Release bufs from the uma cache back to the buffer queues. 1621 */ 1622static void 1623buf_release(void *arg, void **store, int cnt) 1624{ 1625 struct bufqueue *bq; 1626 struct buf *bp; 1627 int i; 1628 1629 bq = &bqempty; 1630 BQ_LOCK(bq); 1631 for (i = 0; i < cnt; i++) { 1632 bp = store[i]; 1633 /* Inline bq_insert() to batch locking. */ 1634 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist); 1635 bp->b_flags &= ~(B_AGE | B_REUSE); 1636 bq->bq_len++; 1637 bp->b_qindex = bq->bq_index; 1638 } 1639 BQ_UNLOCK(bq); 1640} 1641 1642/* 1643 * buf_alloc: 1644 * 1645 * Allocate an empty buffer header. 1646 */ 1647static struct buf * 1648buf_alloc(struct bufdomain *bd) 1649{ 1650 struct buf *bp; 1651 int freebufs, error; 1652 1653 /* 1654 * We can only run out of bufs in the buf zone if the average buf 1655 * is less than BKVASIZE. In this case the actual wait/block will 1656 * come from buf_reycle() failing to flush one of these small bufs. 1657 */ 1658 bp = NULL; 1659 freebufs = atomic_fetchadd_int(&bd->bd_freebuffers, -1); 1660 if (freebufs > 0) 1661 bp = uma_zalloc(buf_zone, M_NOWAIT); 1662 if (bp == NULL) { 1663 atomic_add_int(&bd->bd_freebuffers, 1); 1664 bufspace_daemon_wakeup(bd); 1665 counter_u64_add(numbufallocfails, 1); 1666 return (NULL); 1667 } 1668 /* 1669 * Wake-up the bufspace daemon on transition below threshold. 1670 */ 1671 if (freebufs == bd->bd_lofreebuffers) 1672 bufspace_daemon_wakeup(bd); 1673 1674 error = BUF_LOCK(bp, LK_EXCLUSIVE, NULL); 1675 KASSERT(error == 0, ("%s: BUF_LOCK on free buf %p: %d.", __func__, bp, 1676 error)); 1677 (void)error; 1678 1679 KASSERT(bp->b_vp == NULL, 1680 ("bp: %p still has vnode %p.", bp, bp->b_vp)); 1681 KASSERT((bp->b_flags & (B_DELWRI | B_NOREUSE)) == 0, 1682 ("invalid buffer %p flags %#x", bp, bp->b_flags)); 1683 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 1684 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags)); 1685 KASSERT(bp->b_npages == 0, 1686 ("bp: %p still has %d vm pages\n", bp, bp->b_npages)); 1687 KASSERT(bp->b_kvasize == 0, ("bp: %p still has kva\n", bp)); 1688 KASSERT(bp->b_bufsize == 0, ("bp: %p still has bufspace\n", bp)); 1689 MPASS((bp->b_flags & B_MAXPHYS) == 0); 1690 1691 bp->b_domain = BD_DOMAIN(bd); 1692 bp->b_flags = 0; 1693 bp->b_ioflags = 0; 1694 bp->b_xflags = 0; 1695 bp->b_vflags = 0; 1696 bp->b_vp = NULL; 1697 bp->b_blkno = bp->b_lblkno = 0; 1698 bp->b_offset = NOOFFSET; 1699 bp->b_iodone = 0; 1700 bp->b_error = 0; 1701 bp->b_resid = 0; 1702 bp->b_bcount = 0; 1703 bp->b_npages = 0; 1704 bp->b_dirtyoff = bp->b_dirtyend = 0; 1705 bp->b_bufobj = NULL; 1706 bp->b_data = bp->b_kvabase = unmapped_buf; 1707 bp->b_fsprivate1 = NULL; 1708 bp->b_fsprivate2 = NULL; 1709 bp->b_fsprivate3 = NULL; 1710 LIST_INIT(&bp->b_dep); 1711 1712 return (bp); 1713} 1714 1715/* 1716 * buf_recycle: 1717 * 1718 * Free a buffer from the given bufqueue. kva controls whether the 1719 * freed buf must own some kva resources. This is used for 1720 * defragmenting. 1721 */ 1722static int 1723buf_recycle(struct bufdomain *bd, bool kva) 1724{ 1725 struct bufqueue *bq; 1726 struct buf *bp, *nbp; 1727 1728 if (kva) 1729 counter_u64_add(bufdefragcnt, 1); 1730 nbp = NULL; 1731 bq = bd->bd_cleanq; 1732 BQ_LOCK(bq); 1733 KASSERT(BQ_LOCKPTR(bq) == BD_LOCKPTR(bd), 1734 ("buf_recycle: Locks don't match")); 1735 nbp = TAILQ_FIRST(&bq->bq_queue); 1736 1737 /* 1738 * Run scan, possibly freeing data and/or kva mappings on the fly 1739 * depending. 1740 */ 1741 while ((bp = nbp) != NULL) { 1742 /* 1743 * Calculate next bp (we can only use it if we do not 1744 * release the bqlock). 1745 */ 1746 nbp = TAILQ_NEXT(bp, b_freelist); 1747 1748 /* 1749 * If we are defragging then we need a buffer with 1750 * some kva to reclaim. 1751 */ 1752 if (kva && bp->b_kvasize == 0) 1753 continue; 1754 1755 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1756 continue; 1757 1758 /* 1759 * Implement a second chance algorithm for frequently 1760 * accessed buffers. 1761 */ 1762 if ((bp->b_flags & B_REUSE) != 0) { 1763 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist); 1764 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist); 1765 bp->b_flags &= ~B_REUSE; 1766 BUF_UNLOCK(bp); 1767 continue; 1768 } 1769 1770 /* 1771 * Skip buffers with background writes in progress. 1772 */ 1773 if ((bp->b_vflags & BV_BKGRDINPROG) != 0) { 1774 BUF_UNLOCK(bp); 1775 continue; 1776 } 1777 1778 KASSERT(bp->b_qindex == QUEUE_CLEAN, 1779 ("buf_recycle: inconsistent queue %d bp %p", 1780 bp->b_qindex, bp)); 1781 KASSERT(bp->b_domain == BD_DOMAIN(bd), 1782 ("getnewbuf: queue domain %d doesn't match request %d", 1783 bp->b_domain, (int)BD_DOMAIN(bd))); 1784 /* 1785 * NOTE: nbp is now entirely invalid. We can only restart 1786 * the scan from this point on. 1787 */ 1788 bq_remove(bq, bp); 1789 BQ_UNLOCK(bq); 1790 1791 /* 1792 * Requeue the background write buffer with error and 1793 * restart the scan. 1794 */ 1795 if ((bp->b_vflags & BV_BKGRDERR) != 0) { 1796 bqrelse(bp); 1797 BQ_LOCK(bq); 1798 nbp = TAILQ_FIRST(&bq->bq_queue); 1799 continue; 1800 } 1801 bp->b_flags |= B_INVAL; 1802 brelse(bp); 1803 return (0); 1804 } 1805 bd->bd_wanted = 1; 1806 BQ_UNLOCK(bq); 1807 1808 return (ENOBUFS); 1809} 1810 1811/* 1812 * bremfree: 1813 * 1814 * Mark the buffer for removal from the appropriate free list. 1815 * 1816 */ 1817void 1818bremfree(struct buf *bp) 1819{ 1820 1821 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1822 KASSERT((bp->b_flags & B_REMFREE) == 0, 1823 ("bremfree: buffer %p already marked for delayed removal.", bp)); 1824 KASSERT(bp->b_qindex != QUEUE_NONE, 1825 ("bremfree: buffer %p not on a queue.", bp)); 1826 BUF_ASSERT_XLOCKED(bp); 1827 1828 bp->b_flags |= B_REMFREE; 1829} 1830 1831/* 1832 * bremfreef: 1833 * 1834 * Force an immediate removal from a free list. Used only in nfs when 1835 * it abuses the b_freelist pointer. 1836 */ 1837void 1838bremfreef(struct buf *bp) 1839{ 1840 struct bufqueue *bq; 1841 1842 bq = bufqueue_acquire(bp); 1843 bq_remove(bq, bp); 1844 BQ_UNLOCK(bq); 1845} 1846 1847static void 1848bq_init(struct bufqueue *bq, int qindex, int subqueue, const char *lockname) 1849{ 1850 1851 mtx_init(&bq->bq_lock, lockname, NULL, MTX_DEF); 1852 TAILQ_INIT(&bq->bq_queue); 1853 bq->bq_len = 0; 1854 bq->bq_index = qindex; 1855 bq->bq_subqueue = subqueue; 1856} 1857 1858static void 1859bd_init(struct bufdomain *bd) 1860{ 1861 int i; 1862 1863 bd->bd_cleanq = &bd->bd_subq[mp_maxid + 1]; 1864 bq_init(bd->bd_cleanq, QUEUE_CLEAN, mp_maxid + 1, "bufq clean lock"); 1865 bq_init(&bd->bd_dirtyq, QUEUE_DIRTY, -1, "bufq dirty lock"); 1866 for (i = 0; i <= mp_maxid; i++) 1867 bq_init(&bd->bd_subq[i], QUEUE_CLEAN, i, 1868 "bufq clean subqueue lock"); 1869 mtx_init(&bd->bd_run_lock, "bufspace daemon run lock", NULL, MTX_DEF); 1870} 1871 1872/* 1873 * bq_remove: 1874 * 1875 * Removes a buffer from the free list, must be called with the 1876 * correct qlock held. 1877 */ 1878static void 1879bq_remove(struct bufqueue *bq, struct buf *bp) 1880{ 1881 1882 CTR3(KTR_BUF, "bq_remove(%p) vp %p flags %X", 1883 bp, bp->b_vp, bp->b_flags); 1884 KASSERT(bp->b_qindex != QUEUE_NONE, 1885 ("bq_remove: buffer %p not on a queue.", bp)); 1886 KASSERT(bufqueue(bp) == bq, 1887 ("bq_remove: Remove buffer %p from wrong queue.", bp)); 1888 1889 BQ_ASSERT_LOCKED(bq); 1890 if (bp->b_qindex != QUEUE_EMPTY) { 1891 BUF_ASSERT_XLOCKED(bp); 1892 } 1893 KASSERT(bq->bq_len >= 1, 1894 ("queue %d underflow", bp->b_qindex)); 1895 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist); 1896 bq->bq_len--; 1897 bp->b_qindex = QUEUE_NONE; 1898 bp->b_flags &= ~(B_REMFREE | B_REUSE); 1899} 1900 1901static void 1902bd_flush(struct bufdomain *bd, struct bufqueue *bq) 1903{ 1904 struct buf *bp; 1905 1906 BQ_ASSERT_LOCKED(bq); 1907 if (bq != bd->bd_cleanq) { 1908 BD_LOCK(bd); 1909 while ((bp = TAILQ_FIRST(&bq->bq_queue)) != NULL) { 1910 TAILQ_REMOVE(&bq->bq_queue, bp, b_freelist); 1911 TAILQ_INSERT_TAIL(&bd->bd_cleanq->bq_queue, bp, 1912 b_freelist); 1913 bp->b_subqueue = bd->bd_cleanq->bq_subqueue; 1914 } 1915 bd->bd_cleanq->bq_len += bq->bq_len; 1916 bq->bq_len = 0; 1917 } 1918 if (bd->bd_wanted) { 1919 bd->bd_wanted = 0; 1920 wakeup(&bd->bd_wanted); 1921 } 1922 if (bq != bd->bd_cleanq) 1923 BD_UNLOCK(bd); 1924} 1925 1926static int 1927bd_flushall(struct bufdomain *bd) 1928{ 1929 struct bufqueue *bq; 1930 int flushed; 1931 int i; 1932 1933 if (bd->bd_lim == 0) 1934 return (0); 1935 flushed = 0; 1936 for (i = 0; i <= mp_maxid; i++) { 1937 bq = &bd->bd_subq[i]; 1938 if (bq->bq_len == 0) 1939 continue; 1940 BQ_LOCK(bq); 1941 bd_flush(bd, bq); 1942 BQ_UNLOCK(bq); 1943 flushed++; 1944 } 1945 1946 return (flushed); 1947} 1948 1949static void 1950bq_insert(struct bufqueue *bq, struct buf *bp, bool unlock) 1951{ 1952 struct bufdomain *bd; 1953 1954 if (bp->b_qindex != QUEUE_NONE) 1955 panic("bq_insert: free buffer %p onto another queue?", bp); 1956 1957 bd = bufdomain(bp); 1958 if (bp->b_flags & B_AGE) { 1959 /* Place this buf directly on the real queue. */ 1960 if (bq->bq_index == QUEUE_CLEAN) 1961 bq = bd->bd_cleanq; 1962 BQ_LOCK(bq); 1963 TAILQ_INSERT_HEAD(&bq->bq_queue, bp, b_freelist); 1964 } else { 1965 BQ_LOCK(bq); 1966 TAILQ_INSERT_TAIL(&bq->bq_queue, bp, b_freelist); 1967 } 1968 bp->b_flags &= ~(B_AGE | B_REUSE); 1969 bq->bq_len++; 1970 bp->b_qindex = bq->bq_index; 1971 bp->b_subqueue = bq->bq_subqueue; 1972 1973 /* 1974 * Unlock before we notify so that we don't wakeup a waiter that 1975 * fails a trylock on the buf and sleeps again. 1976 */ 1977 if (unlock) 1978 BUF_UNLOCK(bp); 1979 1980 if (bp->b_qindex == QUEUE_CLEAN) { 1981 /* 1982 * Flush the per-cpu queue and notify any waiters. 1983 */ 1984 if (bd->bd_wanted || (bq != bd->bd_cleanq && 1985 bq->bq_len >= bd->bd_lim)) 1986 bd_flush(bd, bq); 1987 } 1988 BQ_UNLOCK(bq); 1989} 1990 1991/* 1992 * bufkva_free: 1993 * 1994 * Free the kva allocation for a buffer. 1995 * 1996 */ 1997static void 1998bufkva_free(struct buf *bp) 1999{ 2000 2001#ifdef INVARIANTS 2002 if (bp->b_kvasize == 0) { 2003 KASSERT(bp->b_kvabase == unmapped_buf && 2004 bp->b_data == unmapped_buf, 2005 ("Leaked KVA space on %p", bp)); 2006 } else if (buf_mapped(bp)) 2007 BUF_CHECK_MAPPED(bp); 2008 else 2009 BUF_CHECK_UNMAPPED(bp); 2010#endif 2011 if (bp->b_kvasize == 0) 2012 return; 2013 2014 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, bp->b_kvasize); 2015 counter_u64_add(bufkvaspace, -bp->b_kvasize); 2016 counter_u64_add(buffreekvacnt, 1); 2017 bp->b_data = bp->b_kvabase = unmapped_buf; 2018 bp->b_kvasize = 0; 2019} 2020 2021/* 2022 * bufkva_alloc: 2023 * 2024 * Allocate the buffer KVA and set b_kvasize and b_kvabase. 2025 */ 2026static int 2027bufkva_alloc(struct buf *bp, int maxsize, int gbflags) 2028{ 2029 vm_offset_t addr; 2030 int error; 2031 2032 KASSERT((gbflags & GB_UNMAPPED) == 0 || (gbflags & GB_KVAALLOC) != 0, 2033 ("Invalid gbflags 0x%x in %s", gbflags, __func__)); 2034 MPASS((bp->b_flags & B_MAXPHYS) == 0); 2035 KASSERT(maxsize <= maxbcachebuf, 2036 ("bufkva_alloc kva too large %d %u", maxsize, maxbcachebuf)); 2037 2038 bufkva_free(bp); 2039 2040 addr = 0; 2041 error = vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr); 2042 if (error != 0) { 2043 /* 2044 * Buffer map is too fragmented. Request the caller 2045 * to defragment the map. 2046 */ 2047 return (error); 2048 } 2049 bp->b_kvabase = (caddr_t)addr; 2050 bp->b_kvasize = maxsize; 2051 counter_u64_add(bufkvaspace, bp->b_kvasize); 2052 if ((gbflags & GB_UNMAPPED) != 0) { 2053 bp->b_data = unmapped_buf; 2054 BUF_CHECK_UNMAPPED(bp); 2055 } else { 2056 bp->b_data = bp->b_kvabase; 2057 BUF_CHECK_MAPPED(bp); 2058 } 2059 return (0); 2060} 2061 2062/* 2063 * bufkva_reclaim: 2064 * 2065 * Reclaim buffer kva by freeing buffers holding kva. This is a vmem 2066 * callback that fires to avoid returning failure. 2067 */ 2068static void 2069bufkva_reclaim(vmem_t *vmem, int flags) 2070{ 2071 bool done; 2072 int q; 2073 int i; 2074 2075 done = false; 2076 for (i = 0; i < 5; i++) { 2077 for (q = 0; q < buf_domains; q++) 2078 if (buf_recycle(&bdomain[q], true) != 0) 2079 done = true; 2080 if (done) 2081 break; 2082 } 2083 return; 2084} 2085 2086/* 2087 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 2088 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 2089 * the buffer is valid and we do not have to do anything. 2090 */ 2091static void 2092breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, int cnt, 2093 struct ucred * cred, int flags, void (*ckhashfunc)(struct buf *)) 2094{ 2095 struct buf *rabp; 2096 struct thread *td; 2097 int i; 2098 2099 td = curthread; 2100 2101 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 2102 if (inmem(vp, *rablkno)) 2103 continue; 2104 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 2105 if ((rabp->b_flags & B_CACHE) != 0) { 2106 brelse(rabp); 2107 continue; 2108 } 2109#ifdef RACCT 2110 if (racct_enable) { 2111 PROC_LOCK(curproc); 2112 racct_add_buf(curproc, rabp, 0); 2113 PROC_UNLOCK(curproc); 2114 } 2115#endif /* RACCT */ 2116 td->td_ru.ru_inblock++; 2117 rabp->b_flags |= B_ASYNC; 2118 rabp->b_flags &= ~B_INVAL; 2119 if ((flags & GB_CKHASH) != 0) { 2120 rabp->b_flags |= B_CKHASH; 2121 rabp->b_ckhashcalc = ckhashfunc; 2122 } 2123 rabp->b_ioflags &= ~BIO_ERROR; 2124 rabp->b_iocmd = BIO_READ; 2125 if (rabp->b_rcred == NOCRED && cred != NOCRED) 2126 rabp->b_rcred = crhold(cred); 2127 vfs_busy_pages(rabp, 0); 2128 BUF_KERNPROC(rabp); 2129 rabp->b_iooffset = dbtob(rabp->b_blkno); 2130 bstrategy(rabp); 2131 } 2132} 2133 2134/* 2135 * Entry point for bread() and breadn() via #defines in sys/buf.h. 2136 * 2137 * Get a buffer with the specified data. Look in the cache first. We 2138 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 2139 * is set, the buffer is valid and we do not have to do anything, see 2140 * getblk(). Also starts asynchronous I/O on read-ahead blocks. 2141 * 2142 * Always return a NULL buffer pointer (in bpp) when returning an error. 2143 * 2144 * The blkno parameter is the logical block being requested. Normally 2145 * the mapping of logical block number to disk block address is done 2146 * by calling VOP_BMAP(). However, if the mapping is already known, the 2147 * disk block address can be passed using the dblkno parameter. If the 2148 * disk block address is not known, then the same value should be passed 2149 * for blkno and dblkno. 2150 */ 2151int 2152breadn_flags(struct vnode *vp, daddr_t blkno, daddr_t dblkno, int size, 2153 daddr_t *rablkno, int *rabsize, int cnt, struct ucred *cred, int flags, 2154 void (*ckhashfunc)(struct buf *), struct buf **bpp) 2155{ 2156 struct buf *bp; 2157 struct thread *td; 2158 int error, readwait, rv; 2159 2160 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 2161 td = curthread; 2162 /* 2163 * Can only return NULL if GB_LOCK_NOWAIT or GB_SPARSE flags 2164 * are specified. 2165 */ 2166 error = getblkx(vp, blkno, dblkno, size, 0, 0, flags, &bp); 2167 if (error != 0) { 2168 *bpp = NULL; 2169 return (error); 2170 } 2171 KASSERT(blkno == bp->b_lblkno, 2172 ("getblkx returned buffer for blkno %jd instead of blkno %jd", 2173 (intmax_t)bp->b_lblkno, (intmax_t)blkno)); 2174 flags &= ~GB_NOSPARSE; 2175 *bpp = bp; 2176 2177 /* 2178 * If not found in cache, do some I/O 2179 */ 2180 readwait = 0; 2181 if ((bp->b_flags & B_CACHE) == 0) { 2182#ifdef RACCT 2183 if (racct_enable) { 2184 PROC_LOCK(td->td_proc); 2185 racct_add_buf(td->td_proc, bp, 0); 2186 PROC_UNLOCK(td->td_proc); 2187 } 2188#endif /* RACCT */ 2189 td->td_ru.ru_inblock++; 2190 bp->b_iocmd = BIO_READ; 2191 bp->b_flags &= ~B_INVAL; 2192 if ((flags & GB_CKHASH) != 0) { 2193 bp->b_flags |= B_CKHASH; 2194 bp->b_ckhashcalc = ckhashfunc; 2195 } 2196 if ((flags & GB_CVTENXIO) != 0) 2197 bp->b_xflags |= BX_CVTENXIO; 2198 bp->b_ioflags &= ~BIO_ERROR; 2199 if (bp->b_rcred == NOCRED && cred != NOCRED) 2200 bp->b_rcred = crhold(cred); 2201 vfs_busy_pages(bp, 0); 2202 bp->b_iooffset = dbtob(bp->b_blkno); 2203 bstrategy(bp); 2204 ++readwait; 2205 } 2206 2207 /* 2208 * Attempt to initiate asynchronous I/O on read-ahead blocks. 2209 */ 2210 breada(vp, rablkno, rabsize, cnt, cred, flags, ckhashfunc); 2211 2212 rv = 0; 2213 if (readwait) { 2214 rv = bufwait(bp); 2215 if (rv != 0) { 2216 brelse(bp); 2217 *bpp = NULL; 2218 } 2219 } 2220 return (rv); 2221} 2222 2223/* 2224 * Write, release buffer on completion. (Done by iodone 2225 * if async). Do not bother writing anything if the buffer 2226 * is invalid. 2227 * 2228 * Note that we set B_CACHE here, indicating that buffer is 2229 * fully valid and thus cacheable. This is true even of NFS 2230 * now so we set it generally. This could be set either here 2231 * or in biodone() since the I/O is synchronous. We put it 2232 * here. 2233 */ 2234int 2235bufwrite(struct buf *bp) 2236{ 2237 int oldflags; 2238 struct vnode *vp; 2239 long space; 2240 int vp_md; 2241 2242 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2243 if ((bp->b_bufobj->bo_flag & BO_DEAD) != 0) { 2244 bp->b_flags |= B_INVAL | B_RELBUF; 2245 bp->b_flags &= ~B_CACHE; 2246 brelse(bp); 2247 return (ENXIO); 2248 } 2249 if (bp->b_flags & B_INVAL) { 2250 brelse(bp); 2251 return (0); 2252 } 2253 2254 if (bp->b_flags & B_BARRIER) 2255 atomic_add_long(&barrierwrites, 1); 2256 2257 oldflags = bp->b_flags; 2258 2259 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 2260 ("FFS background buffer should not get here %p", bp)); 2261 2262 vp = bp->b_vp; 2263 if (vp) 2264 vp_md = vp->v_vflag & VV_MD; 2265 else 2266 vp_md = 0; 2267 2268 /* 2269 * Mark the buffer clean. Increment the bufobj write count 2270 * before bundirty() call, to prevent other thread from seeing 2271 * empty dirty list and zero counter for writes in progress, 2272 * falsely indicating that the bufobj is clean. 2273 */ 2274 bufobj_wref(bp->b_bufobj); 2275 bundirty(bp); 2276 2277 bp->b_flags &= ~B_DONE; 2278 bp->b_ioflags &= ~BIO_ERROR; 2279 bp->b_flags |= B_CACHE; 2280 bp->b_iocmd = BIO_WRITE; 2281 2282 vfs_busy_pages(bp, 1); 2283 2284 /* 2285 * Normal bwrites pipeline writes 2286 */ 2287 bp->b_runningbufspace = bp->b_bufsize; 2288 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace); 2289 2290#ifdef RACCT 2291 if (racct_enable) { 2292 PROC_LOCK(curproc); 2293 racct_add_buf(curproc, bp, 1); 2294 PROC_UNLOCK(curproc); 2295 } 2296#endif /* RACCT */ 2297 curthread->td_ru.ru_oublock++; 2298 if (oldflags & B_ASYNC) 2299 BUF_KERNPROC(bp); 2300 bp->b_iooffset = dbtob(bp->b_blkno); 2301 buf_track(bp, __func__); 2302 bstrategy(bp); 2303 2304 if ((oldflags & B_ASYNC) == 0) { 2305 int rtval = bufwait(bp); 2306 brelse(bp); 2307 return (rtval); 2308 } else if (space > hirunningspace) { 2309 /* 2310 * don't allow the async write to saturate the I/O 2311 * system. We will not deadlock here because 2312 * we are blocking waiting for I/O that is already in-progress 2313 * to complete. We do not block here if it is the update 2314 * or syncer daemon trying to clean up as that can lead 2315 * to deadlock. 2316 */ 2317 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 2318 waitrunningbufspace(); 2319 } 2320 2321 return (0); 2322} 2323 2324void 2325bufbdflush(struct bufobj *bo, struct buf *bp) 2326{ 2327 struct buf *nbp; 2328 struct bufdomain *bd; 2329 2330 bd = &bdomain[bo->bo_domain]; 2331 if (bo->bo_dirty.bv_cnt > bd->bd_dirtybufthresh + 10) { 2332 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 2333 altbufferflushes++; 2334 } else if (bo->bo_dirty.bv_cnt > bd->bd_dirtybufthresh) { 2335 BO_LOCK(bo); 2336 /* 2337 * Try to find a buffer to flush. 2338 */ 2339 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 2340 if ((nbp->b_vflags & BV_BKGRDINPROG) || 2341 BUF_LOCK(nbp, 2342 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 2343 continue; 2344 if (bp == nbp) 2345 panic("bdwrite: found ourselves"); 2346 BO_UNLOCK(bo); 2347 /* Don't countdeps with the bo lock held. */ 2348 if (buf_countdeps(nbp, 0)) { 2349 BO_LOCK(bo); 2350 BUF_UNLOCK(nbp); 2351 continue; 2352 } 2353 if (nbp->b_flags & B_CLUSTEROK) { 2354 vfs_bio_awrite(nbp); 2355 } else { 2356 bremfree(nbp); 2357 bawrite(nbp); 2358 } 2359 dirtybufferflushes++; 2360 break; 2361 } 2362 if (nbp == NULL) 2363 BO_UNLOCK(bo); 2364 } 2365} 2366 2367/* 2368 * Delayed write. (Buffer is marked dirty). Do not bother writing 2369 * anything if the buffer is marked invalid. 2370 * 2371 * Note that since the buffer must be completely valid, we can safely 2372 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 2373 * biodone() in order to prevent getblk from writing the buffer 2374 * out synchronously. 2375 */ 2376void 2377bdwrite(struct buf *bp) 2378{ 2379 struct thread *td = curthread; 2380 struct vnode *vp; 2381 struct bufobj *bo; 2382 2383 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2384 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2385 KASSERT((bp->b_flags & B_BARRIER) == 0, 2386 ("Barrier request in delayed write %p", bp)); 2387 2388 if (bp->b_flags & B_INVAL) { 2389 brelse(bp); 2390 return; 2391 } 2392 2393 /* 2394 * If we have too many dirty buffers, don't create any more. 2395 * If we are wildly over our limit, then force a complete 2396 * cleanup. Otherwise, just keep the situation from getting 2397 * out of control. Note that we have to avoid a recursive 2398 * disaster and not try to clean up after our own cleanup! 2399 */ 2400 vp = bp->b_vp; 2401 bo = bp->b_bufobj; 2402 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 2403 td->td_pflags |= TDP_INBDFLUSH; 2404 BO_BDFLUSH(bo, bp); 2405 td->td_pflags &= ~TDP_INBDFLUSH; 2406 } else 2407 recursiveflushes++; 2408 2409 bdirty(bp); 2410 /* 2411 * Set B_CACHE, indicating that the buffer is fully valid. This is 2412 * true even of NFS now. 2413 */ 2414 bp->b_flags |= B_CACHE; 2415 2416 /* 2417 * This bmap keeps the system from needing to do the bmap later, 2418 * perhaps when the system is attempting to do a sync. Since it 2419 * is likely that the indirect block -- or whatever other datastructure 2420 * that the filesystem needs is still in memory now, it is a good 2421 * thing to do this. Note also, that if the pageout daemon is 2422 * requesting a sync -- there might not be enough memory to do 2423 * the bmap then... So, this is important to do. 2424 */ 2425 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 2426 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 2427 } 2428 2429 buf_track(bp, __func__); 2430 2431 /* 2432 * Set the *dirty* buffer range based upon the VM system dirty 2433 * pages. 2434 * 2435 * Mark the buffer pages as clean. We need to do this here to 2436 * satisfy the vnode_pager and the pageout daemon, so that it 2437 * thinks that the pages have been "cleaned". Note that since 2438 * the pages are in a delayed write buffer -- the VFS layer 2439 * "will" see that the pages get written out on the next sync, 2440 * or perhaps the cluster will be completed. 2441 */ 2442 vfs_clean_pages_dirty_buf(bp); 2443 bqrelse(bp); 2444 2445 /* 2446 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 2447 * due to the softdep code. 2448 */ 2449} 2450 2451/* 2452 * bdirty: 2453 * 2454 * Turn buffer into delayed write request. We must clear BIO_READ and 2455 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 2456 * itself to properly update it in the dirty/clean lists. We mark it 2457 * B_DONE to ensure that any asynchronization of the buffer properly 2458 * clears B_DONE ( else a panic will occur later ). 2459 * 2460 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 2461 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 2462 * should only be called if the buffer is known-good. 2463 * 2464 * Since the buffer is not on a queue, we do not update the numfreebuffers 2465 * count. 2466 * 2467 * The buffer must be on QUEUE_NONE. 2468 */ 2469void 2470bdirty(struct buf *bp) 2471{ 2472 2473 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 2474 bp, bp->b_vp, bp->b_flags); 2475 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2476 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 2477 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 2478 bp->b_flags &= ~(B_RELBUF); 2479 bp->b_iocmd = BIO_WRITE; 2480 2481 if ((bp->b_flags & B_DELWRI) == 0) { 2482 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 2483 reassignbuf(bp); 2484 bdirtyadd(bp); 2485 } 2486} 2487 2488/* 2489 * bundirty: 2490 * 2491 * Clear B_DELWRI for buffer. 2492 * 2493 * Since the buffer is not on a queue, we do not update the numfreebuffers 2494 * count. 2495 * 2496 * The buffer must be on QUEUE_NONE. 2497 */ 2498 2499void 2500bundirty(struct buf *bp) 2501{ 2502 2503 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2504 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2505 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 2506 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 2507 2508 if (bp->b_flags & B_DELWRI) { 2509 bp->b_flags &= ~B_DELWRI; 2510 reassignbuf(bp); 2511 bdirtysub(bp); 2512 } 2513 /* 2514 * Since it is now being written, we can clear its deferred write flag. 2515 */ 2516 bp->b_flags &= ~B_DEFERRED; 2517} 2518 2519/* 2520 * bawrite: 2521 * 2522 * Asynchronous write. Start output on a buffer, but do not wait for 2523 * it to complete. The buffer is released when the output completes. 2524 * 2525 * bwrite() ( or the VOP routine anyway ) is responsible for handling 2526 * B_INVAL buffers. Not us. 2527 */ 2528void 2529bawrite(struct buf *bp) 2530{ 2531 2532 bp->b_flags |= B_ASYNC; 2533 (void) bwrite(bp); 2534} 2535 2536/* 2537 * babarrierwrite: 2538 * 2539 * Asynchronous barrier write. Start output on a buffer, but do not 2540 * wait for it to complete. Place a write barrier after this write so 2541 * that this buffer and all buffers written before it are committed to 2542 * the disk before any buffers written after this write are committed 2543 * to the disk. The buffer is released when the output completes. 2544 */ 2545void 2546babarrierwrite(struct buf *bp) 2547{ 2548 2549 bp->b_flags |= B_ASYNC | B_BARRIER; 2550 (void) bwrite(bp); 2551} 2552 2553/* 2554 * bbarrierwrite: 2555 * 2556 * Synchronous barrier write. Start output on a buffer and wait for 2557 * it to complete. Place a write barrier after this write so that 2558 * this buffer and all buffers written before it are committed to 2559 * the disk before any buffers written after this write are committed 2560 * to the disk. The buffer is released when the output completes. 2561 */ 2562int 2563bbarrierwrite(struct buf *bp) 2564{ 2565 2566 bp->b_flags |= B_BARRIER; 2567 return (bwrite(bp)); 2568} 2569 2570/* 2571 * bwillwrite: 2572 * 2573 * Called prior to the locking of any vnodes when we are expecting to 2574 * write. We do not want to starve the buffer cache with too many 2575 * dirty buffers so we block here. By blocking prior to the locking 2576 * of any vnodes we attempt to avoid the situation where a locked vnode 2577 * prevents the various system daemons from flushing related buffers. 2578 */ 2579void 2580bwillwrite(void) 2581{ 2582 2583 if (buf_dirty_count_severe()) { 2584 mtx_lock(&bdirtylock); 2585 while (buf_dirty_count_severe()) { 2586 bdirtywait = 1; 2587 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4), 2588 "flswai", 0); 2589 } 2590 mtx_unlock(&bdirtylock); 2591 } 2592} 2593 2594/* 2595 * Return true if we have too many dirty buffers. 2596 */ 2597int 2598buf_dirty_count_severe(void) 2599{ 2600 2601 return (!BIT_EMPTY(BUF_DOMAINS, &bdhidirty)); 2602} 2603 2604/* 2605 * brelse: 2606 * 2607 * Release a busy buffer and, if requested, free its resources. The 2608 * buffer will be stashed in the appropriate bufqueue[] allowing it 2609 * to be accessed later as a cache entity or reused for other purposes. 2610 */ 2611void 2612brelse(struct buf *bp) 2613{ 2614 struct mount *v_mnt; 2615 int qindex; 2616 2617 /* 2618 * Many functions erroneously call brelse with a NULL bp under rare 2619 * error conditions. Simply return when called with a NULL bp. 2620 */ 2621 if (bp == NULL) 2622 return; 2623 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 2624 bp, bp->b_vp, bp->b_flags); 2625 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 2626 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 2627 KASSERT((bp->b_flags & B_VMIO) != 0 || (bp->b_flags & B_NOREUSE) == 0, 2628 ("brelse: non-VMIO buffer marked NOREUSE")); 2629 2630 if (BUF_LOCKRECURSED(bp)) { 2631 /* 2632 * Do not process, in particular, do not handle the 2633 * B_INVAL/B_RELBUF and do not release to free list. 2634 */ 2635 BUF_UNLOCK(bp); 2636 return; 2637 } 2638 2639 if (bp->b_flags & B_MANAGED) { 2640 bqrelse(bp); 2641 return; 2642 } 2643 2644 if (LIST_EMPTY(&bp->b_dep)) { 2645 bp->b_flags &= ~B_IOSTARTED; 2646 } else { 2647 KASSERT((bp->b_flags & B_IOSTARTED) == 0, 2648 ("brelse: SU io not finished bp %p", bp)); 2649 } 2650 2651 if ((bp->b_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) { 2652 BO_LOCK(bp->b_bufobj); 2653 bp->b_vflags &= ~BV_BKGRDERR; 2654 BO_UNLOCK(bp->b_bufobj); 2655 bdirty(bp); 2656 } 2657 2658 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 2659 (bp->b_flags & B_INVALONERR)) { 2660 /* 2661 * Forced invalidation of dirty buffer contents, to be used 2662 * after a failed write in the rare case that the loss of the 2663 * contents is acceptable. The buffer is invalidated and 2664 * freed. 2665 */ 2666 bp->b_flags |= B_INVAL | B_RELBUF | B_NOCACHE; 2667 bp->b_flags &= ~(B_ASYNC | B_CACHE); 2668 } 2669 2670 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 2671 (bp->b_error != ENXIO || !LIST_EMPTY(&bp->b_dep)) && 2672 !(bp->b_flags & B_INVAL)) { 2673 /* 2674 * Failed write, redirty. All errors except ENXIO (which 2675 * means the device is gone) are treated as being 2676 * transient. 2677 * 2678 * XXX Treating EIO as transient is not correct; the 2679 * contract with the local storage device drivers is that 2680 * they will only return EIO once the I/O is no longer 2681 * retriable. Network I/O also respects this through the 2682 * guarantees of TCP and/or the internal retries of NFS. 2683 * ENOMEM might be transient, but we also have no way of 2684 * knowing when its ok to retry/reschedule. In general, 2685 * this entire case should be made obsolete through better 2686 * error handling/recovery and resource scheduling. 2687 * 2688 * Do this also for buffers that failed with ENXIO, but have 2689 * non-empty dependencies - the soft updates code might need 2690 * to access the buffer to untangle them. 2691 * 2692 * Must clear BIO_ERROR to prevent pages from being scrapped. 2693 */ 2694 bp->b_ioflags &= ~BIO_ERROR; 2695 bdirty(bp); 2696 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 2697 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 2698 /* 2699 * Either a failed read I/O, or we were asked to free or not 2700 * cache the buffer, or we failed to write to a device that's 2701 * no longer present. 2702 */ 2703 bp->b_flags |= B_INVAL; 2704 if (!LIST_EMPTY(&bp->b_dep)) 2705 buf_deallocate(bp); 2706 if (bp->b_flags & B_DELWRI) 2707 bdirtysub(bp); 2708 bp->b_flags &= ~(B_DELWRI | B_CACHE); 2709 if ((bp->b_flags & B_VMIO) == 0) { 2710 allocbuf(bp, 0); 2711 if (bp->b_vp) 2712 brelvp(bp); 2713 } 2714 } 2715 2716 /* 2717 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_truncate() 2718 * is called with B_DELWRI set, the underlying pages may wind up 2719 * getting freed causing a previous write (bdwrite()) to get 'lost' 2720 * because pages associated with a B_DELWRI bp are marked clean. 2721 * 2722 * We still allow the B_INVAL case to call vfs_vmio_truncate(), even 2723 * if B_DELWRI is set. 2724 */ 2725 if (bp->b_flags & B_DELWRI) 2726 bp->b_flags &= ~B_RELBUF; 2727 2728 /* 2729 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 2730 * constituted, not even NFS buffers now. Two flags effect this. If 2731 * B_INVAL, the struct buf is invalidated but the VM object is kept 2732 * around ( i.e. so it is trivial to reconstitute the buffer later ). 2733 * 2734 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 2735 * invalidated. BIO_ERROR cannot be set for a failed write unless the 2736 * buffer is also B_INVAL because it hits the re-dirtying code above. 2737 * 2738 * Normally we can do this whether a buffer is B_DELWRI or not. If 2739 * the buffer is an NFS buffer, it is tracking piecemeal writes or 2740 * the commit state and we cannot afford to lose the buffer. If the 2741 * buffer has a background write in progress, we need to keep it 2742 * around to prevent it from being reconstituted and starting a second 2743 * background write. 2744 */ 2745 2746 v_mnt = bp->b_vp != NULL ? bp->b_vp->v_mount : NULL; 2747 2748 if ((bp->b_flags & B_VMIO) && (bp->b_flags & B_NOCACHE || 2749 (bp->b_ioflags & BIO_ERROR && bp->b_iocmd == BIO_READ)) && 2750 (v_mnt == NULL || (v_mnt->mnt_vfc->vfc_flags & VFCF_NETWORK) == 0 || 2751 vn_isdisk(bp->b_vp) || (bp->b_flags & B_DELWRI) == 0)) { 2752 vfs_vmio_invalidate(bp); 2753 allocbuf(bp, 0); 2754 } 2755 2756 if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0 || 2757 (bp->b_flags & (B_DELWRI | B_NOREUSE)) == B_NOREUSE) { 2758 allocbuf(bp, 0); 2759 bp->b_flags &= ~B_NOREUSE; 2760 if (bp->b_vp != NULL) 2761 brelvp(bp); 2762 } 2763 2764 /* 2765 * If the buffer has junk contents signal it and eventually 2766 * clean up B_DELWRI and diassociate the vnode so that gbincore() 2767 * doesn't find it. 2768 */ 2769 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 2770 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 2771 bp->b_flags |= B_INVAL; 2772 if (bp->b_flags & B_INVAL) { 2773 if (bp->b_flags & B_DELWRI) 2774 bundirty(bp); 2775 if (bp->b_vp) 2776 brelvp(bp); 2777 } 2778 2779 buf_track(bp, __func__); 2780 2781 /* buffers with no memory */ 2782 if (bp->b_bufsize == 0) { 2783 buf_free(bp); 2784 return; 2785 } 2786 /* buffers with junk contents */ 2787 if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 2788 (bp->b_ioflags & BIO_ERROR)) { 2789 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 2790 if (bp->b_vflags & BV_BKGRDINPROG) 2791 panic("losing buffer 2"); 2792 qindex = QUEUE_CLEAN; 2793 bp->b_flags |= B_AGE; 2794 /* remaining buffers */ 2795 } else if (bp->b_flags & B_DELWRI) 2796 qindex = QUEUE_DIRTY; 2797 else 2798 qindex = QUEUE_CLEAN; 2799 2800 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 2801 panic("brelse: not dirty"); 2802 2803 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_RELBUF | B_DIRECT); 2804 bp->b_xflags &= ~(BX_CVTENXIO); 2805 /* binsfree unlocks bp. */ 2806 binsfree(bp, qindex); 2807} 2808 2809/* 2810 * Release a buffer back to the appropriate queue but do not try to free 2811 * it. The buffer is expected to be used again soon. 2812 * 2813 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 2814 * biodone() to requeue an async I/O on completion. It is also used when 2815 * known good buffers need to be requeued but we think we may need the data 2816 * again soon. 2817 * 2818 * XXX we should be able to leave the B_RELBUF hint set on completion. 2819 */ 2820void 2821bqrelse(struct buf *bp) 2822{ 2823 int qindex; 2824 2825 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2826 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 2827 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 2828 2829 qindex = QUEUE_NONE; 2830 if (BUF_LOCKRECURSED(bp)) { 2831 /* do not release to free list */ 2832 BUF_UNLOCK(bp); 2833 return; 2834 } 2835 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 2836 bp->b_xflags &= ~(BX_CVTENXIO); 2837 2838 if (LIST_EMPTY(&bp->b_dep)) { 2839 bp->b_flags &= ~B_IOSTARTED; 2840 } else { 2841 KASSERT((bp->b_flags & B_IOSTARTED) == 0, 2842 ("bqrelse: SU io not finished bp %p", bp)); 2843 } 2844 2845 if (bp->b_flags & B_MANAGED) { 2846 if (bp->b_flags & B_REMFREE) 2847 bremfreef(bp); 2848 goto out; 2849 } 2850 2851 /* buffers with stale but valid contents */ 2852 if ((bp->b_flags & B_DELWRI) != 0 || (bp->b_vflags & (BV_BKGRDINPROG | 2853 BV_BKGRDERR)) == BV_BKGRDERR) { 2854 BO_LOCK(bp->b_bufobj); 2855 bp->b_vflags &= ~BV_BKGRDERR; 2856 BO_UNLOCK(bp->b_bufobj); 2857 qindex = QUEUE_DIRTY; 2858 } else { 2859 if ((bp->b_flags & B_DELWRI) == 0 && 2860 (bp->b_xflags & BX_VNDIRTY)) 2861 panic("bqrelse: not dirty"); 2862 if ((bp->b_flags & B_NOREUSE) != 0) { 2863 brelse(bp); 2864 return; 2865 } 2866 qindex = QUEUE_CLEAN; 2867 } 2868 buf_track(bp, __func__); 2869 /* binsfree unlocks bp. */ 2870 binsfree(bp, qindex); 2871 return; 2872 2873out: 2874 buf_track(bp, __func__); 2875 /* unlock */ 2876 BUF_UNLOCK(bp); 2877} 2878 2879/* 2880 * Complete I/O to a VMIO backed page. Validate the pages as appropriate, 2881 * restore bogus pages. 2882 */ 2883static void 2884vfs_vmio_iodone(struct buf *bp) 2885{ 2886 vm_ooffset_t foff; 2887 vm_page_t m; 2888 vm_object_t obj; 2889 struct vnode *vp __unused; 2890 int i, iosize, resid; 2891 bool bogus; 2892 2893 obj = bp->b_bufobj->bo_object; 2894 KASSERT(blockcount_read(&obj->paging_in_progress) >= bp->b_npages, 2895 ("vfs_vmio_iodone: paging in progress(%d) < b_npages(%d)", 2896 blockcount_read(&obj->paging_in_progress), bp->b_npages)); 2897 2898 vp = bp->b_vp; 2899 VNPASS(vp->v_holdcnt > 0, vp); 2900 VNPASS(vp->v_object != NULL, vp); 2901 2902 foff = bp->b_offset; 2903 KASSERT(bp->b_offset != NOOFFSET, 2904 ("vfs_vmio_iodone: bp %p has no buffer offset", bp)); 2905 2906 bogus = false; 2907 iosize = bp->b_bcount - bp->b_resid; 2908 for (i = 0; i < bp->b_npages; i++) { 2909 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 2910 if (resid > iosize) 2911 resid = iosize; 2912 2913 /* 2914 * cleanup bogus pages, restoring the originals 2915 */ 2916 m = bp->b_pages[i]; 2917 if (m == bogus_page) { 2918 bogus = true; 2919 m = vm_page_relookup(obj, OFF_TO_IDX(foff)); 2920 if (m == NULL) 2921 panic("biodone: page disappeared!"); 2922 bp->b_pages[i] = m; 2923 } else if ((bp->b_iocmd == BIO_READ) && resid > 0) { 2924 /* 2925 * In the write case, the valid and clean bits are 2926 * already changed correctly ( see bdwrite() ), so we 2927 * only need to do this here in the read case. 2928 */ 2929 KASSERT((m->dirty & vm_page_bits(foff & PAGE_MASK, 2930 resid)) == 0, ("vfs_vmio_iodone: page %p " 2931 "has unexpected dirty bits", m)); 2932 vfs_page_set_valid(bp, foff, m); 2933 } 2934 KASSERT(OFF_TO_IDX(foff) == m->pindex, 2935 ("vfs_vmio_iodone: foff(%jd)/pindex(%ju) mismatch", 2936 (intmax_t)foff, (uintmax_t)m->pindex)); 2937 2938 vm_page_sunbusy(m); 2939 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2940 iosize -= resid; 2941 } 2942 vm_object_pip_wakeupn(obj, bp->b_npages); 2943 if (bogus && buf_mapped(bp)) { 2944 BUF_CHECK_MAPPED(bp); 2945 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 2946 bp->b_pages, bp->b_npages); 2947 } 2948} 2949 2950/* 2951 * Perform page invalidation when a buffer is released. The fully invalid 2952 * pages will be reclaimed later in vfs_vmio_truncate(). 2953 */ 2954static void 2955vfs_vmio_invalidate(struct buf *bp) 2956{ 2957 vm_object_t obj; 2958 vm_page_t m; 2959 int flags, i, resid, poffset, presid; 2960 2961 if (buf_mapped(bp)) { 2962 BUF_CHECK_MAPPED(bp); 2963 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages); 2964 } else 2965 BUF_CHECK_UNMAPPED(bp); 2966 /* 2967 * Get the base offset and length of the buffer. Note that 2968 * in the VMIO case if the buffer block size is not 2969 * page-aligned then b_data pointer may not be page-aligned. 2970 * But our b_pages[] array *IS* page aligned. 2971 * 2972 * block sizes less then DEV_BSIZE (usually 512) are not 2973 * supported due to the page granularity bits (m->valid, 2974 * m->dirty, etc...). 2975 * 2976 * See man buf(9) for more information 2977 */ 2978 flags = (bp->b_flags & B_NOREUSE) != 0 ? VPR_NOREUSE : 0; 2979 obj = bp->b_bufobj->bo_object; 2980 resid = bp->b_bufsize; 2981 poffset = bp->b_offset & PAGE_MASK; 2982 VM_OBJECT_WLOCK(obj); 2983 for (i = 0; i < bp->b_npages; i++) { 2984 m = bp->b_pages[i]; 2985 if (m == bogus_page) 2986 panic("vfs_vmio_invalidate: Unexpected bogus page."); 2987 bp->b_pages[i] = NULL; 2988 2989 presid = resid > (PAGE_SIZE - poffset) ? 2990 (PAGE_SIZE - poffset) : resid; 2991 KASSERT(presid >= 0, ("brelse: extra page")); 2992 vm_page_busy_acquire(m, VM_ALLOC_SBUSY); 2993 if (pmap_page_wired_mappings(m) == 0) 2994 vm_page_set_invalid(m, poffset, presid); 2995 vm_page_sunbusy(m); 2996 vm_page_release_locked(m, flags); 2997 resid -= presid; 2998 poffset = 0; 2999 } 3000 VM_OBJECT_WUNLOCK(obj); 3001 bp->b_npages = 0; 3002} 3003 3004/* 3005 * Page-granular truncation of an existing VMIO buffer. 3006 */ 3007static void 3008vfs_vmio_truncate(struct buf *bp, int desiredpages) 3009{ 3010 vm_object_t obj; 3011 vm_page_t m; 3012 int flags, i; 3013 3014 if (bp->b_npages == desiredpages) 3015 return; 3016 3017 if (buf_mapped(bp)) { 3018 BUF_CHECK_MAPPED(bp); 3019 pmap_qremove((vm_offset_t)trunc_page((vm_offset_t)bp->b_data) + 3020 (desiredpages << PAGE_SHIFT), bp->b_npages - desiredpages); 3021 } else 3022 BUF_CHECK_UNMAPPED(bp); 3023 3024 /* 3025 * The object lock is needed only if we will attempt to free pages. 3026 */ 3027 flags = (bp->b_flags & B_NOREUSE) != 0 ? VPR_NOREUSE : 0; 3028 if ((bp->b_flags & B_DIRECT) != 0) { 3029 flags |= VPR_TRYFREE; 3030 obj = bp->b_bufobj->bo_object; 3031 VM_OBJECT_WLOCK(obj); 3032 } else { 3033 obj = NULL; 3034 } 3035 for (i = desiredpages; i < bp->b_npages; i++) { 3036 m = bp->b_pages[i]; 3037 KASSERT(m != bogus_page, ("allocbuf: bogus page found")); 3038 bp->b_pages[i] = NULL; 3039 if (obj != NULL) 3040 vm_page_release_locked(m, flags); 3041 else 3042 vm_page_release(m, flags); 3043 } 3044 if (obj != NULL) 3045 VM_OBJECT_WUNLOCK(obj); 3046 bp->b_npages = desiredpages; 3047} 3048 3049/* 3050 * Byte granular extension of VMIO buffers. 3051 */ 3052static void 3053vfs_vmio_extend(struct buf *bp, int desiredpages, int size) 3054{ 3055 /* 3056 * We are growing the buffer, possibly in a 3057 * byte-granular fashion. 3058 */ 3059 vm_object_t obj; 3060 vm_offset_t toff; 3061 vm_offset_t tinc; 3062 vm_page_t m; 3063 3064 /* 3065 * Step 1, bring in the VM pages from the object, allocating 3066 * them if necessary. We must clear B_CACHE if these pages 3067 * are not valid for the range covered by the buffer. 3068 */ 3069 obj = bp->b_bufobj->bo_object; 3070 if (bp->b_npages < desiredpages) { 3071 KASSERT(desiredpages <= atop(maxbcachebuf), 3072 ("vfs_vmio_extend past maxbcachebuf %p %d %u", 3073 bp, desiredpages, maxbcachebuf)); 3074 3075 /* 3076 * We must allocate system pages since blocking 3077 * here could interfere with paging I/O, no 3078 * matter which process we are. 3079 * 3080 * Only exclusive busy can be tested here. 3081 * Blocking on shared busy might lead to 3082 * deadlocks once allocbuf() is called after 3083 * pages are vfs_busy_pages(). 3084 */ 3085 (void)vm_page_grab_pages_unlocked(obj, 3086 OFF_TO_IDX(bp->b_offset) + bp->b_npages, 3087 VM_ALLOC_SYSTEM | VM_ALLOC_IGN_SBUSY | 3088 VM_ALLOC_NOBUSY | VM_ALLOC_WIRED, 3089 &bp->b_pages[bp->b_npages], desiredpages - bp->b_npages); 3090 bp->b_npages = desiredpages; 3091 } 3092 3093 /* 3094 * Step 2. We've loaded the pages into the buffer, 3095 * we have to figure out if we can still have B_CACHE 3096 * set. Note that B_CACHE is set according to the 3097 * byte-granular range ( bcount and size ), not the 3098 * aligned range ( newbsize ). 3099 * 3100 * The VM test is against m->valid, which is DEV_BSIZE 3101 * aligned. Needless to say, the validity of the data 3102 * needs to also be DEV_BSIZE aligned. Note that this 3103 * fails with NFS if the server or some other client 3104 * extends the file's EOF. If our buffer is resized, 3105 * B_CACHE may remain set! XXX 3106 */ 3107 toff = bp->b_bcount; 3108 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 3109 while ((bp->b_flags & B_CACHE) && toff < size) { 3110 vm_pindex_t pi; 3111 3112 if (tinc > (size - toff)) 3113 tinc = size - toff; 3114 pi = ((bp->b_offset & PAGE_MASK) + toff) >> PAGE_SHIFT; 3115 m = bp->b_pages[pi]; 3116 vfs_buf_test_cache(bp, bp->b_offset, toff, tinc, m); 3117 toff += tinc; 3118 tinc = PAGE_SIZE; 3119 } 3120 3121 /* 3122 * Step 3, fixup the KVA pmap. 3123 */ 3124 if (buf_mapped(bp)) 3125 bpmap_qenter(bp); 3126 else 3127 BUF_CHECK_UNMAPPED(bp); 3128} 3129 3130/* 3131 * Check to see if a block at a particular lbn is available for a clustered 3132 * write. 3133 */ 3134static int 3135vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 3136{ 3137 struct buf *bpa; 3138 int match; 3139 3140 match = 0; 3141 3142 /* If the buf isn't in core skip it */ 3143 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 3144 return (0); 3145 3146 /* If the buf is busy we don't want to wait for it */ 3147 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 3148 return (0); 3149 3150 /* Only cluster with valid clusterable delayed write buffers */ 3151 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 3152 (B_DELWRI | B_CLUSTEROK)) 3153 goto done; 3154 3155 if (bpa->b_bufsize != size) 3156 goto done; 3157 3158 /* 3159 * Check to see if it is in the expected place on disk and that the 3160 * block has been mapped. 3161 */ 3162 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 3163 match = 1; 3164done: 3165 BUF_UNLOCK(bpa); 3166 return (match); 3167} 3168 3169/* 3170 * vfs_bio_awrite: 3171 * 3172 * Implement clustered async writes for clearing out B_DELWRI buffers. 3173 * This is much better then the old way of writing only one buffer at 3174 * a time. Note that we may not be presented with the buffers in the 3175 * correct order, so we search for the cluster in both directions. 3176 */ 3177int 3178vfs_bio_awrite(struct buf *bp) 3179{ 3180 struct bufobj *bo; 3181 int i; 3182 int j; 3183 daddr_t lblkno = bp->b_lblkno; 3184 struct vnode *vp = bp->b_vp; 3185 int ncl; 3186 int nwritten; 3187 int size; 3188 int maxcl; 3189 int gbflags; 3190 3191 bo = &vp->v_bufobj; 3192 gbflags = (bp->b_data == unmapped_buf) ? GB_UNMAPPED : 0; 3193 /* 3194 * right now we support clustered writing only to regular files. If 3195 * we find a clusterable block we could be in the middle of a cluster 3196 * rather then at the beginning. 3197 */ 3198 if ((vp->v_type == VREG) && 3199 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 3200 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 3201 size = vp->v_mount->mnt_stat.f_iosize; 3202 maxcl = maxphys / size; 3203 3204 BO_RLOCK(bo); 3205 for (i = 1; i < maxcl; i++) 3206 if (vfs_bio_clcheck(vp, size, lblkno + i, 3207 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 3208 break; 3209 3210 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 3211 if (vfs_bio_clcheck(vp, size, lblkno - j, 3212 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 3213 break; 3214 BO_RUNLOCK(bo); 3215 --j; 3216 ncl = i + j; 3217 /* 3218 * this is a possible cluster write 3219 */ 3220 if (ncl != 1) { 3221 BUF_UNLOCK(bp); 3222 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl, 3223 gbflags); 3224 return (nwritten); 3225 } 3226 } 3227 bremfree(bp); 3228 bp->b_flags |= B_ASYNC; 3229 /* 3230 * default (old) behavior, writing out only one block 3231 * 3232 * XXX returns b_bufsize instead of b_bcount for nwritten? 3233 */ 3234 nwritten = bp->b_bufsize; 3235 (void) bwrite(bp); 3236 3237 return (nwritten); 3238} 3239 3240/* 3241 * getnewbuf_kva: 3242 * 3243 * Allocate KVA for an empty buf header according to gbflags. 3244 */ 3245static int 3246getnewbuf_kva(struct buf *bp, int gbflags, int maxsize) 3247{ 3248 3249 if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_UNMAPPED) { 3250 /* 3251 * In order to keep fragmentation sane we only allocate kva 3252 * in BKVASIZE chunks. XXX with vmem we can do page size. 3253 */ 3254 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 3255 3256 if (maxsize != bp->b_kvasize && 3257 bufkva_alloc(bp, maxsize, gbflags)) 3258 return (ENOSPC); 3259 } 3260 return (0); 3261} 3262 3263/* 3264 * getnewbuf: 3265 * 3266 * Find and initialize a new buffer header, freeing up existing buffers 3267 * in the bufqueues as necessary. The new buffer is returned locked. 3268 * 3269 * We block if: 3270 * We have insufficient buffer headers 3271 * We have insufficient buffer space 3272 * buffer_arena is too fragmented ( space reservation fails ) 3273 * If we have to flush dirty buffers ( but we try to avoid this ) 3274 * 3275 * The caller is responsible for releasing the reserved bufspace after 3276 * allocbuf() is called. 3277 */ 3278static struct buf * 3279getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int maxsize, int gbflags) 3280{ 3281 struct bufdomain *bd; 3282 struct buf *bp; 3283 bool metadata, reserved; 3284 3285 bp = NULL; 3286 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3287 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3288 if (!unmapped_buf_allowed) 3289 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3290 3291 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 || 3292 vp->v_type == VCHR) 3293 metadata = true; 3294 else 3295 metadata = false; 3296 if (vp == NULL) 3297 bd = &bdomain[0]; 3298 else 3299 bd = &bdomain[vp->v_bufobj.bo_domain]; 3300 3301 counter_u64_add(getnewbufcalls, 1); 3302 reserved = false; 3303 do { 3304 if (reserved == false && 3305 bufspace_reserve(bd, maxsize, metadata) != 0) { 3306 counter_u64_add(getnewbufrestarts, 1); 3307 continue; 3308 } 3309 reserved = true; 3310 if ((bp = buf_alloc(bd)) == NULL) { 3311 counter_u64_add(getnewbufrestarts, 1); 3312 continue; 3313 } 3314 if (getnewbuf_kva(bp, gbflags, maxsize) == 0) 3315 return (bp); 3316 break; 3317 } while (buf_recycle(bd, false) == 0); 3318 3319 if (reserved) 3320 bufspace_release(bd, maxsize); 3321 if (bp != NULL) { 3322 bp->b_flags |= B_INVAL; 3323 brelse(bp); 3324 } 3325 bufspace_wait(bd, vp, gbflags, slpflag, slptimeo); 3326 3327 return (NULL); 3328} 3329 3330/* 3331 * buf_daemon: 3332 * 3333 * buffer flushing daemon. Buffers are normally flushed by the 3334 * update daemon but if it cannot keep up this process starts to 3335 * take the load in an attempt to prevent getnewbuf() from blocking. 3336 */ 3337static struct kproc_desc buf_kp = { 3338 "bufdaemon", 3339 buf_daemon, 3340 &bufdaemonproc 3341}; 3342SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 3343 3344static int 3345buf_flush(struct vnode *vp, struct bufdomain *bd, int target) 3346{ 3347 int flushed; 3348 3349 flushed = flushbufqueues(vp, bd, target, 0); 3350 if (flushed == 0) { 3351 /* 3352 * Could not find any buffers without rollback 3353 * dependencies, so just write the first one 3354 * in the hopes of eventually making progress. 3355 */ 3356 if (vp != NULL && target > 2) 3357 target /= 2; 3358 flushbufqueues(vp, bd, target, 1); 3359 } 3360 return (flushed); 3361} 3362 3363static void 3364buf_daemon() 3365{ 3366 struct bufdomain *bd; 3367 int speedupreq; 3368 int lodirty; 3369 int i; 3370 3371 /* 3372 * This process needs to be suspended prior to shutdown sync. 3373 */ 3374 EVENTHANDLER_REGISTER(shutdown_pre_sync, kthread_shutdown, curthread, 3375 SHUTDOWN_PRI_LAST + 100); 3376 3377 /* 3378 * Start the buf clean daemons as children threads. 3379 */ 3380 for (i = 0 ; i < buf_domains; i++) { 3381 int error; 3382 3383 error = kthread_add((void (*)(void *))bufspace_daemon, 3384 &bdomain[i], curproc, NULL, 0, 0, "bufspacedaemon-%d", i); 3385 if (error) 3386 panic("error %d spawning bufspace daemon", error); 3387 } 3388 3389 /* 3390 * This process is allowed to take the buffer cache to the limit 3391 */ 3392 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 3393 mtx_lock(&bdlock); 3394 for (;;) { 3395 bd_request = 0; 3396 mtx_unlock(&bdlock); 3397 3398 kthread_suspend_check(); 3399 3400 /* 3401 * Save speedupreq for this pass and reset to capture new 3402 * requests. 3403 */ 3404 speedupreq = bd_speedupreq; 3405 bd_speedupreq = 0; 3406 3407 /* 3408 * Flush each domain sequentially according to its level and 3409 * the speedup request. 3410 */ 3411 for (i = 0; i < buf_domains; i++) { 3412 bd = &bdomain[i]; 3413 if (speedupreq) 3414 lodirty = bd->bd_numdirtybuffers / 2; 3415 else 3416 lodirty = bd->bd_lodirtybuffers; 3417 while (bd->bd_numdirtybuffers > lodirty) { 3418 if (buf_flush(NULL, bd, 3419 bd->bd_numdirtybuffers - lodirty) == 0) 3420 break; 3421 kern_yield(PRI_USER); 3422 } 3423 } 3424 3425 /* 3426 * Only clear bd_request if we have reached our low water 3427 * mark. The buf_daemon normally waits 1 second and 3428 * then incrementally flushes any dirty buffers that have 3429 * built up, within reason. 3430 * 3431 * If we were unable to hit our low water mark and couldn't 3432 * find any flushable buffers, we sleep for a short period 3433 * to avoid endless loops on unlockable buffers. 3434 */ 3435 mtx_lock(&bdlock); 3436 if (!BIT_EMPTY(BUF_DOMAINS, &bdlodirty)) { 3437 /* 3438 * We reached our low water mark, reset the 3439 * request and sleep until we are needed again. 3440 * The sleep is just so the suspend code works. 3441 */ 3442 bd_request = 0; 3443 /* 3444 * Do an extra wakeup in case dirty threshold 3445 * changed via sysctl and the explicit transition 3446 * out of shortfall was missed. 3447 */ 3448 bdirtywakeup(); 3449 if (runningbufspace <= lorunningspace) 3450 runningwakeup(); 3451 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 3452 } else { 3453 /* 3454 * We couldn't find any flushable dirty buffers but 3455 * still have too many dirty buffers, we 3456 * have to sleep and try again. (rare) 3457 */ 3458 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 3459 } 3460 } 3461} 3462 3463/* 3464 * flushbufqueues: 3465 * 3466 * Try to flush a buffer in the dirty queue. We must be careful to 3467 * free up B_INVAL buffers instead of write them, which NFS is 3468 * particularly sensitive to. 3469 */ 3470static int flushwithdeps = 0; 3471SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW | CTLFLAG_STATS, 3472 &flushwithdeps, 0, 3473 "Number of buffers flushed with dependecies that require rollbacks"); 3474 3475static int 3476flushbufqueues(struct vnode *lvp, struct bufdomain *bd, int target, 3477 int flushdeps) 3478{ 3479 struct bufqueue *bq; 3480 struct buf *sentinel; 3481 struct vnode *vp; 3482 struct mount *mp; 3483 struct buf *bp; 3484 int hasdeps; 3485 int flushed; 3486 int error; 3487 bool unlock; 3488 3489 flushed = 0; 3490 bq = &bd->bd_dirtyq; 3491 bp = NULL; 3492 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 3493 sentinel->b_qindex = QUEUE_SENTINEL; 3494 BQ_LOCK(bq); 3495 TAILQ_INSERT_HEAD(&bq->bq_queue, sentinel, b_freelist); 3496 BQ_UNLOCK(bq); 3497 while (flushed != target) { 3498 maybe_yield(); 3499 BQ_LOCK(bq); 3500 bp = TAILQ_NEXT(sentinel, b_freelist); 3501 if (bp != NULL) { 3502 TAILQ_REMOVE(&bq->bq_queue, sentinel, b_freelist); 3503 TAILQ_INSERT_AFTER(&bq->bq_queue, bp, sentinel, 3504 b_freelist); 3505 } else { 3506 BQ_UNLOCK(bq); 3507 break; 3508 } 3509 /* 3510 * Skip sentinels inserted by other invocations of the 3511 * flushbufqueues(), taking care to not reorder them. 3512 * 3513 * Only flush the buffers that belong to the 3514 * vnode locked by the curthread. 3515 */ 3516 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL && 3517 bp->b_vp != lvp)) { 3518 BQ_UNLOCK(bq); 3519 continue; 3520 } 3521 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL); 3522 BQ_UNLOCK(bq); 3523 if (error != 0) 3524 continue; 3525 3526 /* 3527 * BKGRDINPROG can only be set with the buf and bufobj 3528 * locks both held. We tolerate a race to clear it here. 3529 */ 3530 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 3531 (bp->b_flags & B_DELWRI) == 0) { 3532 BUF_UNLOCK(bp); 3533 continue; 3534 } 3535 if (bp->b_flags & B_INVAL) { 3536 bremfreef(bp); 3537 brelse(bp); 3538 flushed++; 3539 continue; 3540 } 3541 3542 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 3543 if (flushdeps == 0) { 3544 BUF_UNLOCK(bp); 3545 continue; 3546 } 3547 hasdeps = 1; 3548 } else 3549 hasdeps = 0; 3550 /* 3551 * We must hold the lock on a vnode before writing 3552 * one of its buffers. Otherwise we may confuse, or 3553 * in the case of a snapshot vnode, deadlock the 3554 * system. 3555 * 3556 * The lock order here is the reverse of the normal 3557 * of vnode followed by buf lock. This is ok because 3558 * the NOWAIT will prevent deadlock. 3559 */ 3560 vp = bp->b_vp; 3561 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 3562 BUF_UNLOCK(bp); 3563 continue; 3564 } 3565 if (lvp == NULL) { 3566 unlock = true; 3567 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT); 3568 } else { 3569 ASSERT_VOP_LOCKED(vp, "getbuf"); 3570 unlock = false; 3571 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 : 3572 vn_lock(vp, LK_TRYUPGRADE); 3573 } 3574 if (error == 0) { 3575 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 3576 bp, bp->b_vp, bp->b_flags); 3577 if (curproc == bufdaemonproc) { 3578 vfs_bio_awrite(bp); 3579 } else { 3580 bremfree(bp); 3581 bwrite(bp); 3582 counter_u64_add(notbufdflushes, 1); 3583 } 3584 vn_finished_write(mp); 3585 if (unlock) 3586 VOP_UNLOCK(vp); 3587 flushwithdeps += hasdeps; 3588 flushed++; 3589 3590 /* 3591 * Sleeping on runningbufspace while holding 3592 * vnode lock leads to deadlock. 3593 */ 3594 if (curproc == bufdaemonproc && 3595 runningbufspace > hirunningspace) 3596 waitrunningbufspace(); 3597 continue; 3598 } 3599 vn_finished_write(mp); 3600 BUF_UNLOCK(bp); 3601 } 3602 BQ_LOCK(bq); 3603 TAILQ_REMOVE(&bq->bq_queue, sentinel, b_freelist); 3604 BQ_UNLOCK(bq); 3605 free(sentinel, M_TEMP); 3606 return (flushed); 3607} 3608 3609/* 3610 * Check to see if a block is currently memory resident. 3611 */ 3612struct buf * 3613incore(struct bufobj *bo, daddr_t blkno) 3614{ 3615 return (gbincore_unlocked(bo, blkno)); 3616} 3617 3618/* 3619 * Returns true if no I/O is needed to access the 3620 * associated VM object. This is like incore except 3621 * it also hunts around in the VM system for the data. 3622 */ 3623bool 3624inmem(struct vnode * vp, daddr_t blkno) 3625{ 3626 vm_object_t obj; 3627 vm_offset_t toff, tinc, size; 3628 vm_page_t m, n; 3629 vm_ooffset_t off; 3630 int valid; 3631 3632 ASSERT_VOP_LOCKED(vp, "inmem"); 3633 3634 if (incore(&vp->v_bufobj, blkno)) 3635 return (true); 3636 if (vp->v_mount == NULL) 3637 return (false); 3638 obj = vp->v_object; 3639 if (obj == NULL) 3640 return (false); 3641 3642 size = PAGE_SIZE; 3643 if (size > vp->v_mount->mnt_stat.f_iosize) 3644 size = vp->v_mount->mnt_stat.f_iosize; 3645 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 3646 3647 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 3648 m = vm_page_lookup_unlocked(obj, OFF_TO_IDX(off + toff)); 3649recheck: 3650 if (m == NULL) 3651 return (false); 3652 3653 tinc = size; 3654 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 3655 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 3656 /* 3657 * Consider page validity only if page mapping didn't change 3658 * during the check. 3659 */ 3660 valid = vm_page_is_valid(m, 3661 (vm_offset_t)((toff + off) & PAGE_MASK), tinc); 3662 n = vm_page_lookup_unlocked(obj, OFF_TO_IDX(off + toff)); 3663 if (m != n) { 3664 m = n; 3665 goto recheck; 3666 } 3667 if (!valid) 3668 return (false); 3669 } 3670 return (true); 3671} 3672 3673/* 3674 * Set the dirty range for a buffer based on the status of the dirty 3675 * bits in the pages comprising the buffer. The range is limited 3676 * to the size of the buffer. 3677 * 3678 * Tell the VM system that the pages associated with this buffer 3679 * are clean. This is used for delayed writes where the data is 3680 * going to go to disk eventually without additional VM intevention. 3681 * 3682 * Note that while we only really need to clean through to b_bcount, we 3683 * just go ahead and clean through to b_bufsize. 3684 */ 3685static void 3686vfs_clean_pages_dirty_buf(struct buf *bp) 3687{ 3688 vm_ooffset_t foff, noff, eoff; 3689 vm_page_t m; 3690 int i; 3691 3692 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 3693 return; 3694 3695 foff = bp->b_offset; 3696 KASSERT(bp->b_offset != NOOFFSET, 3697 ("vfs_clean_pages_dirty_buf: no buffer offset")); 3698 3699 vfs_busy_pages_acquire(bp); 3700 vfs_setdirty_range(bp); 3701 for (i = 0; i < bp->b_npages; i++) { 3702 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3703 eoff = noff; 3704 if (eoff > bp->b_offset + bp->b_bufsize) 3705 eoff = bp->b_offset + bp->b_bufsize; 3706 m = bp->b_pages[i]; 3707 vfs_page_set_validclean(bp, foff, m); 3708 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3709 foff = noff; 3710 } 3711 vfs_busy_pages_release(bp); 3712} 3713 3714static void 3715vfs_setdirty_range(struct buf *bp) 3716{ 3717 vm_offset_t boffset; 3718 vm_offset_t eoffset; 3719 int i; 3720 3721 /* 3722 * test the pages to see if they have been modified directly 3723 * by users through the VM system. 3724 */ 3725 for (i = 0; i < bp->b_npages; i++) 3726 vm_page_test_dirty(bp->b_pages[i]); 3727 3728 /* 3729 * Calculate the encompassing dirty range, boffset and eoffset, 3730 * (eoffset - boffset) bytes. 3731 */ 3732 3733 for (i = 0; i < bp->b_npages; i++) { 3734 if (bp->b_pages[i]->dirty) 3735 break; 3736 } 3737 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3738 3739 for (i = bp->b_npages - 1; i >= 0; --i) { 3740 if (bp->b_pages[i]->dirty) { 3741 break; 3742 } 3743 } 3744 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3745 3746 /* 3747 * Fit it to the buffer. 3748 */ 3749 3750 if (eoffset > bp->b_bcount) 3751 eoffset = bp->b_bcount; 3752 3753 /* 3754 * If we have a good dirty range, merge with the existing 3755 * dirty range. 3756 */ 3757 3758 if (boffset < eoffset) { 3759 if (bp->b_dirtyoff > boffset) 3760 bp->b_dirtyoff = boffset; 3761 if (bp->b_dirtyend < eoffset) 3762 bp->b_dirtyend = eoffset; 3763 } 3764} 3765 3766/* 3767 * Allocate the KVA mapping for an existing buffer. 3768 * If an unmapped buffer is provided but a mapped buffer is requested, take 3769 * also care to properly setup mappings between pages and KVA. 3770 */ 3771static void 3772bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags) 3773{ 3774 int bsize, maxsize, need_mapping, need_kva; 3775 off_t offset; 3776 3777 need_mapping = bp->b_data == unmapped_buf && 3778 (gbflags & GB_UNMAPPED) == 0; 3779 need_kva = bp->b_kvabase == unmapped_buf && 3780 bp->b_data == unmapped_buf && 3781 (gbflags & GB_KVAALLOC) != 0; 3782 if (!need_mapping && !need_kva) 3783 return; 3784 3785 BUF_CHECK_UNMAPPED(bp); 3786 3787 if (need_mapping && bp->b_kvabase != unmapped_buf) { 3788 /* 3789 * Buffer is not mapped, but the KVA was already 3790 * reserved at the time of the instantiation. Use the 3791 * allocated space. 3792 */ 3793 goto has_addr; 3794 } 3795 3796 /* 3797 * Calculate the amount of the address space we would reserve 3798 * if the buffer was mapped. 3799 */ 3800 bsize = vn_isdisk(bp->b_vp) ? DEV_BSIZE : bp->b_bufobj->bo_bsize; 3801 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3802 offset = blkno * bsize; 3803 maxsize = size + (offset & PAGE_MASK); 3804 maxsize = imax(maxsize, bsize); 3805 3806 while (bufkva_alloc(bp, maxsize, gbflags) != 0) { 3807 if ((gbflags & GB_NOWAIT_BD) != 0) { 3808 /* 3809 * XXXKIB: defragmentation cannot 3810 * succeed, not sure what else to do. 3811 */ 3812 panic("GB_NOWAIT_BD and GB_UNMAPPED %p", bp); 3813 } 3814 counter_u64_add(mappingrestarts, 1); 3815 bufspace_wait(bufdomain(bp), bp->b_vp, gbflags, 0, 0); 3816 } 3817has_addr: 3818 if (need_mapping) { 3819 /* b_offset is handled by bpmap_qenter. */ 3820 bp->b_data = bp->b_kvabase; 3821 BUF_CHECK_MAPPED(bp); 3822 bpmap_qenter(bp); 3823 } 3824} 3825 3826struct buf * 3827getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3828 int flags) 3829{ 3830 struct buf *bp; 3831 int error; 3832 3833 error = getblkx(vp, blkno, blkno, size, slpflag, slptimeo, flags, &bp); 3834 if (error != 0) 3835 return (NULL); 3836 return (bp); 3837} 3838 3839/* 3840 * getblkx: 3841 * 3842 * Get a block given a specified block and offset into a file/device. 3843 * The buffers B_DONE bit will be cleared on return, making it almost 3844 * ready for an I/O initiation. B_INVAL may or may not be set on 3845 * return. The caller should clear B_INVAL prior to initiating a 3846 * READ. 3847 * 3848 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 3849 * an existing buffer. 3850 * 3851 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 3852 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 3853 * and then cleared based on the backing VM. If the previous buffer is 3854 * non-0-sized but invalid, B_CACHE will be cleared. 3855 * 3856 * If getblk() must create a new buffer, the new buffer is returned with 3857 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 3858 * case it is returned with B_INVAL clear and B_CACHE set based on the 3859 * backing VM. 3860 * 3861 * getblk() also forces a bwrite() for any B_DELWRI buffer whose 3862 * B_CACHE bit is clear. 3863 * 3864 * What this means, basically, is that the caller should use B_CACHE to 3865 * determine whether the buffer is fully valid or not and should clear 3866 * B_INVAL prior to issuing a read. If the caller intends to validate 3867 * the buffer by loading its data area with something, the caller needs 3868 * to clear B_INVAL. If the caller does this without issuing an I/O, 3869 * the caller should set B_CACHE ( as an optimization ), else the caller 3870 * should issue the I/O and biodone() will set B_CACHE if the I/O was 3871 * a write attempt or if it was a successful read. If the caller 3872 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 3873 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 3874 * 3875 * The blkno parameter is the logical block being requested. Normally 3876 * the mapping of logical block number to disk block address is done 3877 * by calling VOP_BMAP(). However, if the mapping is already known, the 3878 * disk block address can be passed using the dblkno parameter. If the 3879 * disk block address is not known, then the same value should be passed 3880 * for blkno and dblkno. 3881 */ 3882int 3883getblkx(struct vnode *vp, daddr_t blkno, daddr_t dblkno, int size, int slpflag, 3884 int slptimeo, int flags, struct buf **bpp) 3885{ 3886 struct buf *bp; 3887 struct bufobj *bo; 3888 daddr_t d_blkno; 3889 int bsize, error, maxsize, vmio; 3890 off_t offset; 3891 3892 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 3893 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3894 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3895 ASSERT_VOP_LOCKED(vp, "getblk"); 3896 if (size > maxbcachebuf) 3897 panic("getblk: size(%d) > maxbcachebuf(%d)\n", size, 3898 maxbcachebuf); 3899 if (!unmapped_buf_allowed) 3900 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3901 3902 bo = &vp->v_bufobj; 3903 d_blkno = dblkno; 3904 3905 /* Attempt lockless lookup first. */ 3906 bp = gbincore_unlocked(bo, blkno); 3907 if (bp == NULL) 3908 goto newbuf_unlocked; 3909 3910 error = BUF_TIMELOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL, "getblku", 0, 3911 0); 3912 if (error != 0) 3913 goto loop; 3914 3915 /* Verify buf identify has not changed since lookup. */ 3916 if (bp->b_bufobj == bo && bp->b_lblkno == blkno) 3917 goto foundbuf_fastpath; 3918 3919 /* It changed, fallback to locked lookup. */ 3920 BUF_UNLOCK_RAW(bp); 3921 3922loop: 3923 BO_RLOCK(bo); 3924 bp = gbincore(bo, blkno); 3925 if (bp != NULL) { 3926 int lockflags; 3927 3928 /* 3929 * Buffer is in-core. If the buffer is not busy nor managed, 3930 * it must be on a queue. 3931 */ 3932 lockflags = LK_EXCLUSIVE | LK_INTERLOCK | 3933 ((flags & GB_LOCK_NOWAIT) ? LK_NOWAIT : LK_SLEEPFAIL); 3934 3935 error = BUF_TIMELOCK(bp, lockflags, 3936 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo); 3937 3938 /* 3939 * If we slept and got the lock we have to restart in case 3940 * the buffer changed identities. 3941 */ 3942 if (error == ENOLCK) 3943 goto loop; 3944 /* We timed out or were interrupted. */ 3945 else if (error != 0) 3946 return (error); 3947 3948foundbuf_fastpath: 3949 /* If recursed, assume caller knows the rules. */ 3950 if (BUF_LOCKRECURSED(bp)) 3951 goto end; 3952 3953 /* 3954 * The buffer is locked. B_CACHE is cleared if the buffer is 3955 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 3956 * and for a VMIO buffer B_CACHE is adjusted according to the 3957 * backing VM cache. 3958 */ 3959 if (bp->b_flags & B_INVAL) 3960 bp->b_flags &= ~B_CACHE; 3961 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 3962 bp->b_flags |= B_CACHE; 3963 if (bp->b_flags & B_MANAGED) 3964 MPASS(bp->b_qindex == QUEUE_NONE); 3965 else 3966 bremfree(bp); 3967 3968 /* 3969 * check for size inconsistencies for non-VMIO case. 3970 */ 3971 if (bp->b_bcount != size) { 3972 if ((bp->b_flags & B_VMIO) == 0 || 3973 (size > bp->b_kvasize)) { 3974 if (bp->b_flags & B_DELWRI) { 3975 bp->b_flags |= B_NOCACHE; 3976 bwrite(bp); 3977 } else { 3978 if (LIST_EMPTY(&bp->b_dep)) { 3979 bp->b_flags |= B_RELBUF; 3980 brelse(bp); 3981 } else { 3982 bp->b_flags |= B_NOCACHE; 3983 bwrite(bp); 3984 } 3985 } 3986 goto loop; 3987 } 3988 } 3989 3990 /* 3991 * Handle the case of unmapped buffer which should 3992 * become mapped, or the buffer for which KVA 3993 * reservation is requested. 3994 */ 3995 bp_unmapped_get_kva(bp, blkno, size, flags); 3996 3997 /* 3998 * If the size is inconsistent in the VMIO case, we can resize 3999 * the buffer. This might lead to B_CACHE getting set or 4000 * cleared. If the size has not changed, B_CACHE remains 4001 * unchanged from its previous state. 4002 */ 4003 allocbuf(bp, size); 4004 4005 KASSERT(bp->b_offset != NOOFFSET, 4006 ("getblk: no buffer offset")); 4007 4008 /* 4009 * A buffer with B_DELWRI set and B_CACHE clear must 4010 * be committed before we can return the buffer in 4011 * order to prevent the caller from issuing a read 4012 * ( due to B_CACHE not being set ) and overwriting 4013 * it. 4014 * 4015 * Most callers, including NFS and FFS, need this to 4016 * operate properly either because they assume they 4017 * can issue a read if B_CACHE is not set, or because 4018 * ( for example ) an uncached B_DELWRI might loop due 4019 * to softupdates re-dirtying the buffer. In the latter 4020 * case, B_CACHE is set after the first write completes, 4021 * preventing further loops. 4022 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 4023 * above while extending the buffer, we cannot allow the 4024 * buffer to remain with B_CACHE set after the write 4025 * completes or it will represent a corrupt state. To 4026 * deal with this we set B_NOCACHE to scrap the buffer 4027 * after the write. 4028 * 4029 * We might be able to do something fancy, like setting 4030 * B_CACHE in bwrite() except if B_DELWRI is already set, 4031 * so the below call doesn't set B_CACHE, but that gets real 4032 * confusing. This is much easier. 4033 */ 4034 4035 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 4036 bp->b_flags |= B_NOCACHE; 4037 bwrite(bp); 4038 goto loop; 4039 } 4040 bp->b_flags &= ~B_DONE; 4041 } else { 4042 /* 4043 * Buffer is not in-core, create new buffer. The buffer 4044 * returned by getnewbuf() is locked. Note that the returned 4045 * buffer is also considered valid (not marked B_INVAL). 4046 */ 4047 BO_RUNLOCK(bo); 4048newbuf_unlocked: 4049 /* 4050 * If the user does not want us to create the buffer, bail out 4051 * here. 4052 */ 4053 if (flags & GB_NOCREAT) 4054 return (EEXIST); 4055 4056 bsize = vn_isdisk(vp) ? DEV_BSIZE : bo->bo_bsize; 4057 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 4058 offset = blkno * bsize; 4059 vmio = vp->v_object != NULL; 4060 if (vmio) { 4061 maxsize = size + (offset & PAGE_MASK); 4062 } else { 4063 maxsize = size; 4064 /* Do not allow non-VMIO notmapped buffers. */ 4065 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 4066 } 4067 maxsize = imax(maxsize, bsize); 4068 if ((flags & GB_NOSPARSE) != 0 && vmio && 4069 !vn_isdisk(vp)) { 4070 error = VOP_BMAP(vp, blkno, NULL, &d_blkno, 0, 0); 4071 KASSERT(error != EOPNOTSUPP, 4072 ("GB_NOSPARSE from fs not supporting bmap, vp %p", 4073 vp)); 4074 if (error != 0) 4075 return (error); 4076 if (d_blkno == -1) 4077 return (EJUSTRETURN); 4078 } 4079 4080 bp = getnewbuf(vp, slpflag, slptimeo, maxsize, flags); 4081 if (bp == NULL) { 4082 if (slpflag || slptimeo) 4083 return (ETIMEDOUT); 4084 /* 4085 * XXX This is here until the sleep path is diagnosed 4086 * enough to work under very low memory conditions. 4087 * 4088 * There's an issue on low memory, 4BSD+non-preempt 4089 * systems (eg MIPS routers with 32MB RAM) where buffer 4090 * exhaustion occurs without sleeping for buffer 4091 * reclaimation. This just sticks in a loop and 4092 * constantly attempts to allocate a buffer, which 4093 * hits exhaustion and tries to wakeup bufdaemon. 4094 * This never happens because we never yield. 4095 * 4096 * The real solution is to identify and fix these cases 4097 * so we aren't effectively busy-waiting in a loop 4098 * until the reclaimation path has cycles to run. 4099 */ 4100 kern_yield(PRI_USER); 4101 goto loop; 4102 } 4103 4104 /* 4105 * This code is used to make sure that a buffer is not 4106 * created while the getnewbuf routine is blocked. 4107 * This can be a problem whether the vnode is locked or not. 4108 * If the buffer is created out from under us, we have to 4109 * throw away the one we just created. 4110 * 4111 * Note: this must occur before we associate the buffer 4112 * with the vp especially considering limitations in 4113 * the splay tree implementation when dealing with duplicate 4114 * lblkno's. 4115 */ 4116 BO_LOCK(bo); 4117 if (gbincore(bo, blkno)) { 4118 BO_UNLOCK(bo); 4119 bp->b_flags |= B_INVAL; 4120 bufspace_release(bufdomain(bp), maxsize); 4121 brelse(bp); 4122 goto loop; 4123 } 4124 4125 /* 4126 * Insert the buffer into the hash, so that it can 4127 * be found by incore. 4128 */ 4129 bp->b_lblkno = blkno; 4130 bp->b_blkno = d_blkno; 4131 bp->b_offset = offset; 4132 bgetvp(vp, bp); 4133 BO_UNLOCK(bo); 4134 4135 /* 4136 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 4137 * buffer size starts out as 0, B_CACHE will be set by 4138 * allocbuf() for the VMIO case prior to it testing the 4139 * backing store for validity. 4140 */ 4141 4142 if (vmio) { 4143 bp->b_flags |= B_VMIO; 4144 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 4145 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 4146 bp, vp->v_object, bp->b_bufobj->bo_object)); 4147 } else { 4148 bp->b_flags &= ~B_VMIO; 4149 KASSERT(bp->b_bufobj->bo_object == NULL, 4150 ("ARGH! has b_bufobj->bo_object %p %p\n", 4151 bp, bp->b_bufobj->bo_object)); 4152 BUF_CHECK_MAPPED(bp); 4153 } 4154 4155 allocbuf(bp, size); 4156 bufspace_release(bufdomain(bp), maxsize); 4157 bp->b_flags &= ~B_DONE; 4158 } 4159 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 4160end: 4161 buf_track(bp, __func__); 4162 KASSERT(bp->b_bufobj == bo, 4163 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 4164 *bpp = bp; 4165 return (0); 4166} 4167 4168/* 4169 * Get an empty, disassociated buffer of given size. The buffer is initially 4170 * set to B_INVAL. 4171 */ 4172struct buf * 4173geteblk(int size, int flags) 4174{ 4175 struct buf *bp; 4176 int maxsize; 4177 4178 maxsize = (size + BKVAMASK) & ~BKVAMASK; 4179 while ((bp = getnewbuf(NULL, 0, 0, maxsize, flags)) == NULL) { 4180 if ((flags & GB_NOWAIT_BD) && 4181 (curthread->td_pflags & TDP_BUFNEED) != 0) 4182 return (NULL); 4183 } 4184 allocbuf(bp, size); 4185 bufspace_release(bufdomain(bp), maxsize); 4186 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 4187 return (bp); 4188} 4189 4190/* 4191 * Truncate the backing store for a non-vmio buffer. 4192 */ 4193static void 4194vfs_nonvmio_truncate(struct buf *bp, int newbsize) 4195{ 4196 4197 if (bp->b_flags & B_MALLOC) { 4198 /* 4199 * malloced buffers are not shrunk 4200 */ 4201 if (newbsize == 0) { 4202 bufmallocadjust(bp, 0); 4203 free(bp->b_data, M_BIOBUF); 4204 bp->b_data = bp->b_kvabase; 4205 bp->b_flags &= ~B_MALLOC; 4206 } 4207 return; 4208 } 4209 vm_hold_free_pages(bp, newbsize); 4210 bufspace_adjust(bp, newbsize); 4211} 4212 4213/* 4214 * Extend the backing for a non-VMIO buffer. 4215 */ 4216static void 4217vfs_nonvmio_extend(struct buf *bp, int newbsize) 4218{ 4219 caddr_t origbuf; 4220 int origbufsize; 4221 4222 /* 4223 * We only use malloced memory on the first allocation. 4224 * and revert to page-allocated memory when the buffer 4225 * grows. 4226 * 4227 * There is a potential smp race here that could lead 4228 * to bufmallocspace slightly passing the max. It 4229 * is probably extremely rare and not worth worrying 4230 * over. 4231 */ 4232 if (bp->b_bufsize == 0 && newbsize <= PAGE_SIZE/2 && 4233 bufmallocspace < maxbufmallocspace) { 4234 bp->b_data = malloc(newbsize, M_BIOBUF, M_WAITOK); 4235 bp->b_flags |= B_MALLOC; 4236 bufmallocadjust(bp, newbsize); 4237 return; 4238 } 4239 4240 /* 4241 * If the buffer is growing on its other-than-first 4242 * allocation then we revert to the page-allocation 4243 * scheme. 4244 */ 4245 origbuf = NULL; 4246 origbufsize = 0; 4247 if (bp->b_flags & B_MALLOC) { 4248 origbuf = bp->b_data; 4249 origbufsize = bp->b_bufsize; 4250 bp->b_data = bp->b_kvabase; 4251 bufmallocadjust(bp, 0); 4252 bp->b_flags &= ~B_MALLOC; 4253 newbsize = round_page(newbsize); 4254 } 4255 vm_hold_load_pages(bp, (vm_offset_t) bp->b_data + bp->b_bufsize, 4256 (vm_offset_t) bp->b_data + newbsize); 4257 if (origbuf != NULL) { 4258 bcopy(origbuf, bp->b_data, origbufsize); 4259 free(origbuf, M_BIOBUF); 4260 } 4261 bufspace_adjust(bp, newbsize); 4262} 4263 4264/* 4265 * This code constitutes the buffer memory from either anonymous system 4266 * memory (in the case of non-VMIO operations) or from an associated 4267 * VM object (in the case of VMIO operations). This code is able to 4268 * resize a buffer up or down. 4269 * 4270 * Note that this code is tricky, and has many complications to resolve 4271 * deadlock or inconsistent data situations. Tread lightly!!! 4272 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 4273 * the caller. Calling this code willy nilly can result in the loss of data. 4274 * 4275 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 4276 * B_CACHE for the non-VMIO case. 4277 */ 4278int 4279allocbuf(struct buf *bp, int size) 4280{ 4281 int newbsize; 4282 4283 if (bp->b_bcount == size) 4284 return (1); 4285 4286 if (bp->b_kvasize != 0 && bp->b_kvasize < size) 4287 panic("allocbuf: buffer too small"); 4288 4289 newbsize = roundup2(size, DEV_BSIZE); 4290 if ((bp->b_flags & B_VMIO) == 0) { 4291 if ((bp->b_flags & B_MALLOC) == 0) 4292 newbsize = round_page(newbsize); 4293 /* 4294 * Just get anonymous memory from the kernel. Don't 4295 * mess with B_CACHE. 4296 */ 4297 if (newbsize < bp->b_bufsize) 4298 vfs_nonvmio_truncate(bp, newbsize); 4299 else if (newbsize > bp->b_bufsize) 4300 vfs_nonvmio_extend(bp, newbsize); 4301 } else { 4302 int desiredpages; 4303 4304 desiredpages = (size == 0) ? 0 : 4305 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 4306 4307 if (bp->b_flags & B_MALLOC) 4308 panic("allocbuf: VMIO buffer can't be malloced"); 4309 /* 4310 * Set B_CACHE initially if buffer is 0 length or will become 4311 * 0-length. 4312 */ 4313 if (size == 0 || bp->b_bufsize == 0) 4314 bp->b_flags |= B_CACHE; 4315 4316 if (newbsize < bp->b_bufsize) 4317 vfs_vmio_truncate(bp, desiredpages); 4318 /* XXX This looks as if it should be newbsize > b_bufsize */ 4319 else if (size > bp->b_bcount) 4320 vfs_vmio_extend(bp, desiredpages, size); 4321 bufspace_adjust(bp, newbsize); 4322 } 4323 bp->b_bcount = size; /* requested buffer size. */ 4324 return (1); 4325} 4326 4327extern int inflight_transient_maps; 4328 4329static struct bio_queue nondump_bios; 4330 4331void 4332biodone(struct bio *bp) 4333{ 4334 struct mtx *mtxp; 4335 void (*done)(struct bio *); 4336 vm_offset_t start, end; 4337 4338 biotrack(bp, __func__); 4339 4340 /* 4341 * Avoid completing I/O when dumping after a panic since that may 4342 * result in a deadlock in the filesystem or pager code. Note that 4343 * this doesn't affect dumps that were started manually since we aim 4344 * to keep the system usable after it has been resumed. 4345 */ 4346 if (__predict_false(dumping && SCHEDULER_STOPPED())) { 4347 TAILQ_INSERT_HEAD(&nondump_bios, bp, bio_queue); 4348 return; 4349 } 4350 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) { 4351 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING; 4352 bp->bio_flags |= BIO_UNMAPPED; 4353 start = trunc_page((vm_offset_t)bp->bio_data); 4354 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length); 4355 bp->bio_data = unmapped_buf; 4356 pmap_qremove(start, atop(end - start)); 4357 vmem_free(transient_arena, start, end - start); 4358 atomic_add_int(&inflight_transient_maps, -1); 4359 } 4360 done = bp->bio_done; 4361 if (done == NULL) { 4362 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4363 mtx_lock(mtxp); 4364 bp->bio_flags |= BIO_DONE; 4365 wakeup(bp); 4366 mtx_unlock(mtxp); 4367 } else 4368 done(bp); 4369} 4370 4371/* 4372 * Wait for a BIO to finish. 4373 */ 4374int 4375biowait(struct bio *bp, const char *wchan) 4376{ 4377 struct mtx *mtxp; 4378 4379 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4380 mtx_lock(mtxp); 4381 while ((bp->bio_flags & BIO_DONE) == 0) 4382 msleep(bp, mtxp, PRIBIO, wchan, 0); 4383 mtx_unlock(mtxp); 4384 if (bp->bio_error != 0) 4385 return (bp->bio_error); 4386 if (!(bp->bio_flags & BIO_ERROR)) 4387 return (0); 4388 return (EIO); 4389} 4390 4391void 4392biofinish(struct bio *bp, struct devstat *stat, int error) 4393{ 4394 4395 if (error) { 4396 bp->bio_error = error; 4397 bp->bio_flags |= BIO_ERROR; 4398 } 4399 if (stat != NULL) 4400 devstat_end_transaction_bio(stat, bp); 4401 biodone(bp); 4402} 4403 4404#if defined(BUF_TRACKING) || defined(FULL_BUF_TRACKING) 4405void 4406biotrack_buf(struct bio *bp, const char *location) 4407{ 4408 4409 buf_track(bp->bio_track_bp, location); 4410} 4411#endif 4412 4413/* 4414 * bufwait: 4415 * 4416 * Wait for buffer I/O completion, returning error status. The buffer 4417 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 4418 * error and cleared. 4419 */ 4420int 4421bufwait(struct buf *bp) 4422{ 4423 if (bp->b_iocmd == BIO_READ) 4424 bwait(bp, PRIBIO, "biord"); 4425 else 4426 bwait(bp, PRIBIO, "biowr"); 4427 if (bp->b_flags & B_EINTR) { 4428 bp->b_flags &= ~B_EINTR; 4429 return (EINTR); 4430 } 4431 if (bp->b_ioflags & BIO_ERROR) { 4432 return (bp->b_error ? bp->b_error : EIO); 4433 } else { 4434 return (0); 4435 } 4436} 4437 4438/* 4439 * bufdone: 4440 * 4441 * Finish I/O on a buffer, optionally calling a completion function. 4442 * This is usually called from an interrupt so process blocking is 4443 * not allowed. 4444 * 4445 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 4446 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 4447 * assuming B_INVAL is clear. 4448 * 4449 * For the VMIO case, we set B_CACHE if the op was a read and no 4450 * read error occurred, or if the op was a write. B_CACHE is never 4451 * set if the buffer is invalid or otherwise uncacheable. 4452 * 4453 * bufdone does not mess with B_INVAL, allowing the I/O routine or the 4454 * initiator to leave B_INVAL set to brelse the buffer out of existence 4455 * in the biodone routine. 4456 */ 4457void 4458bufdone(struct buf *bp) 4459{ 4460 struct bufobj *dropobj; 4461 void (*biodone)(struct buf *); 4462 4463 buf_track(bp, __func__); 4464 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 4465 dropobj = NULL; 4466 4467 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 4468 4469 runningbufwakeup(bp); 4470 if (bp->b_iocmd == BIO_WRITE) 4471 dropobj = bp->b_bufobj; 4472 /* call optional completion function if requested */ 4473 if (bp->b_iodone != NULL) { 4474 biodone = bp->b_iodone; 4475 bp->b_iodone = NULL; 4476 (*biodone) (bp); 4477 if (dropobj) 4478 bufobj_wdrop(dropobj); 4479 return; 4480 } 4481 if (bp->b_flags & B_VMIO) { 4482 /* 4483 * Set B_CACHE if the op was a normal read and no error 4484 * occurred. B_CACHE is set for writes in the b*write() 4485 * routines. 4486 */ 4487 if (bp->b_iocmd == BIO_READ && 4488 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 4489 !(bp->b_ioflags & BIO_ERROR)) 4490 bp->b_flags |= B_CACHE; 4491 vfs_vmio_iodone(bp); 4492 } 4493 if (!LIST_EMPTY(&bp->b_dep)) 4494 buf_complete(bp); 4495 if ((bp->b_flags & B_CKHASH) != 0) { 4496 KASSERT(bp->b_iocmd == BIO_READ, 4497 ("bufdone: b_iocmd %d not BIO_READ", bp->b_iocmd)); 4498 KASSERT(buf_mapped(bp), ("bufdone: bp %p not mapped", bp)); 4499 (*bp->b_ckhashcalc)(bp); 4500 } 4501 /* 4502 * For asynchronous completions, release the buffer now. The brelse 4503 * will do a wakeup there if necessary - so no need to do a wakeup 4504 * here in the async case. The sync case always needs to do a wakeup. 4505 */ 4506 if (bp->b_flags & B_ASYNC) { 4507 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || 4508 (bp->b_ioflags & BIO_ERROR)) 4509 brelse(bp); 4510 else 4511 bqrelse(bp); 4512 } else 4513 bdone(bp); 4514 if (dropobj) 4515 bufobj_wdrop(dropobj); 4516} 4517 4518/* 4519 * This routine is called in lieu of iodone in the case of 4520 * incomplete I/O. This keeps the busy status for pages 4521 * consistent. 4522 */ 4523void 4524vfs_unbusy_pages(struct buf *bp) 4525{ 4526 int i; 4527 vm_object_t obj; 4528 vm_page_t m; 4529 4530 runningbufwakeup(bp); 4531 if (!(bp->b_flags & B_VMIO)) 4532 return; 4533 4534 obj = bp->b_bufobj->bo_object; 4535 for (i = 0; i < bp->b_npages; i++) { 4536 m = bp->b_pages[i]; 4537 if (m == bogus_page) { 4538 m = vm_page_relookup(obj, OFF_TO_IDX(bp->b_offset) + i); 4539 if (!m) 4540 panic("vfs_unbusy_pages: page missing\n"); 4541 bp->b_pages[i] = m; 4542 if (buf_mapped(bp)) { 4543 BUF_CHECK_MAPPED(bp); 4544 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4545 bp->b_pages, bp->b_npages); 4546 } else 4547 BUF_CHECK_UNMAPPED(bp); 4548 } 4549 vm_page_sunbusy(m); 4550 } 4551 vm_object_pip_wakeupn(obj, bp->b_npages); 4552} 4553 4554/* 4555 * vfs_page_set_valid: 4556 * 4557 * Set the valid bits in a page based on the supplied offset. The 4558 * range is restricted to the buffer's size. 4559 * 4560 * This routine is typically called after a read completes. 4561 */ 4562static void 4563vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4564{ 4565 vm_ooffset_t eoff; 4566 4567 /* 4568 * Compute the end offset, eoff, such that [off, eoff) does not span a 4569 * page boundary and eoff is not greater than the end of the buffer. 4570 * The end of the buffer, in this case, is our file EOF, not the 4571 * allocation size of the buffer. 4572 */ 4573 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 4574 if (eoff > bp->b_offset + bp->b_bcount) 4575 eoff = bp->b_offset + bp->b_bcount; 4576 4577 /* 4578 * Set valid range. This is typically the entire buffer and thus the 4579 * entire page. 4580 */ 4581 if (eoff > off) 4582 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off); 4583} 4584 4585/* 4586 * vfs_page_set_validclean: 4587 * 4588 * Set the valid bits and clear the dirty bits in a page based on the 4589 * supplied offset. The range is restricted to the buffer's size. 4590 */ 4591static void 4592vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4593{ 4594 vm_ooffset_t soff, eoff; 4595 4596 /* 4597 * Start and end offsets in buffer. eoff - soff may not cross a 4598 * page boundary or cross the end of the buffer. The end of the 4599 * buffer, in this case, is our file EOF, not the allocation size 4600 * of the buffer. 4601 */ 4602 soff = off; 4603 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4604 if (eoff > bp->b_offset + bp->b_bcount) 4605 eoff = bp->b_offset + bp->b_bcount; 4606 4607 /* 4608 * Set valid range. This is typically the entire buffer and thus the 4609 * entire page. 4610 */ 4611 if (eoff > soff) { 4612 vm_page_set_validclean( 4613 m, 4614 (vm_offset_t) (soff & PAGE_MASK), 4615 (vm_offset_t) (eoff - soff) 4616 ); 4617 } 4618} 4619 4620/* 4621 * Acquire a shared busy on all pages in the buf. 4622 */ 4623void 4624vfs_busy_pages_acquire(struct buf *bp) 4625{ 4626 int i; 4627 4628 for (i = 0; i < bp->b_npages; i++) 4629 vm_page_busy_acquire(bp->b_pages[i], VM_ALLOC_SBUSY); 4630} 4631 4632void 4633vfs_busy_pages_release(struct buf *bp) 4634{ 4635 int i; 4636 4637 for (i = 0; i < bp->b_npages; i++) 4638 vm_page_sunbusy(bp->b_pages[i]); 4639} 4640 4641/* 4642 * This routine is called before a device strategy routine. 4643 * It is used to tell the VM system that paging I/O is in 4644 * progress, and treat the pages associated with the buffer 4645 * almost as being exclusive busy. Also the object paging_in_progress 4646 * flag is handled to make sure that the object doesn't become 4647 * inconsistent. 4648 * 4649 * Since I/O has not been initiated yet, certain buffer flags 4650 * such as BIO_ERROR or B_INVAL may be in an inconsistent state 4651 * and should be ignored. 4652 */ 4653void 4654vfs_busy_pages(struct buf *bp, int clear_modify) 4655{ 4656 vm_object_t obj; 4657 vm_ooffset_t foff; 4658 vm_page_t m; 4659 int i; 4660 bool bogus; 4661 4662 if (!(bp->b_flags & B_VMIO)) 4663 return; 4664 4665 obj = bp->b_bufobj->bo_object; 4666 foff = bp->b_offset; 4667 KASSERT(bp->b_offset != NOOFFSET, 4668 ("vfs_busy_pages: no buffer offset")); 4669 if ((bp->b_flags & B_CLUSTER) == 0) { 4670 vm_object_pip_add(obj, bp->b_npages); 4671 vfs_busy_pages_acquire(bp); 4672 } 4673 if (bp->b_bufsize != 0) 4674 vfs_setdirty_range(bp); 4675 bogus = false; 4676 for (i = 0; i < bp->b_npages; i++) { 4677 m = bp->b_pages[i]; 4678 vm_page_assert_sbusied(m); 4679 4680 /* 4681 * When readying a buffer for a read ( i.e 4682 * clear_modify == 0 ), it is important to do 4683 * bogus_page replacement for valid pages in 4684 * partially instantiated buffers. Partially 4685 * instantiated buffers can, in turn, occur when 4686 * reconstituting a buffer from its VM backing store 4687 * base. We only have to do this if B_CACHE is 4688 * clear ( which causes the I/O to occur in the 4689 * first place ). The replacement prevents the read 4690 * I/O from overwriting potentially dirty VM-backed 4691 * pages. XXX bogus page replacement is, uh, bogus. 4692 * It may not work properly with small-block devices. 4693 * We need to find a better way. 4694 */ 4695 if (clear_modify) { 4696 pmap_remove_write(m); 4697 vfs_page_set_validclean(bp, foff, m); 4698 } else if (vm_page_all_valid(m) && 4699 (bp->b_flags & B_CACHE) == 0) { 4700 bp->b_pages[i] = bogus_page; 4701 bogus = true; 4702 } 4703 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4704 } 4705 if (bogus && buf_mapped(bp)) { 4706 BUF_CHECK_MAPPED(bp); 4707 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4708 bp->b_pages, bp->b_npages); 4709 } 4710} 4711 4712/* 4713 * vfs_bio_set_valid: 4714 * 4715 * Set the range within the buffer to valid. The range is 4716 * relative to the beginning of the buffer, b_offset. Note that 4717 * b_offset itself may be offset from the beginning of the first 4718 * page. 4719 */ 4720void 4721vfs_bio_set_valid(struct buf *bp, int base, int size) 4722{ 4723 int i, n; 4724 vm_page_t m; 4725 4726 if (!(bp->b_flags & B_VMIO)) 4727 return; 4728 4729 /* 4730 * Fixup base to be relative to beginning of first page. 4731 * Set initial n to be the maximum number of bytes in the 4732 * first page that can be validated. 4733 */ 4734 base += (bp->b_offset & PAGE_MASK); 4735 n = PAGE_SIZE - (base & PAGE_MASK); 4736 4737 /* 4738 * Busy may not be strictly necessary here because the pages are 4739 * unlikely to be fully valid and the vnode lock will synchronize 4740 * their access via getpages. It is grabbed for consistency with 4741 * other page validation. 4742 */ 4743 vfs_busy_pages_acquire(bp); 4744 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4745 m = bp->b_pages[i]; 4746 if (n > size) 4747 n = size; 4748 vm_page_set_valid_range(m, base & PAGE_MASK, n); 4749 base += n; 4750 size -= n; 4751 n = PAGE_SIZE; 4752 } 4753 vfs_busy_pages_release(bp); 4754} 4755 4756/* 4757 * vfs_bio_clrbuf: 4758 * 4759 * If the specified buffer is a non-VMIO buffer, clear the entire 4760 * buffer. If the specified buffer is a VMIO buffer, clear and 4761 * validate only the previously invalid portions of the buffer. 4762 * This routine essentially fakes an I/O, so we need to clear 4763 * BIO_ERROR and B_INVAL. 4764 * 4765 * Note that while we only theoretically need to clear through b_bcount, 4766 * we go ahead and clear through b_bufsize. 4767 */ 4768void 4769vfs_bio_clrbuf(struct buf *bp) 4770{ 4771 int i, j, mask, sa, ea, slide; 4772 4773 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 4774 clrbuf(bp); 4775 return; 4776 } 4777 bp->b_flags &= ~B_INVAL; 4778 bp->b_ioflags &= ~BIO_ERROR; 4779 vfs_busy_pages_acquire(bp); 4780 sa = bp->b_offset & PAGE_MASK; 4781 slide = 0; 4782 for (i = 0; i < bp->b_npages; i++, sa = 0) { 4783 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize); 4784 ea = slide & PAGE_MASK; 4785 if (ea == 0) 4786 ea = PAGE_SIZE; 4787 if (bp->b_pages[i] == bogus_page) 4788 continue; 4789 j = sa / DEV_BSIZE; 4790 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 4791 if ((bp->b_pages[i]->valid & mask) == mask) 4792 continue; 4793 if ((bp->b_pages[i]->valid & mask) == 0) 4794 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa); 4795 else { 4796 for (; sa < ea; sa += DEV_BSIZE, j++) { 4797 if ((bp->b_pages[i]->valid & (1 << j)) == 0) { 4798 pmap_zero_page_area(bp->b_pages[i], 4799 sa, DEV_BSIZE); 4800 } 4801 } 4802 } 4803 vm_page_set_valid_range(bp->b_pages[i], j * DEV_BSIZE, 4804 roundup2(ea - sa, DEV_BSIZE)); 4805 } 4806 vfs_busy_pages_release(bp); 4807 bp->b_resid = 0; 4808} 4809 4810void 4811vfs_bio_bzero_buf(struct buf *bp, int base, int size) 4812{ 4813 vm_page_t m; 4814 int i, n; 4815 4816 if (buf_mapped(bp)) { 4817 BUF_CHECK_MAPPED(bp); 4818 bzero(bp->b_data + base, size); 4819 } else { 4820 BUF_CHECK_UNMAPPED(bp); 4821 n = PAGE_SIZE - (base & PAGE_MASK); 4822 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4823 m = bp->b_pages[i]; 4824 if (n > size) 4825 n = size; 4826 pmap_zero_page_area(m, base & PAGE_MASK, n); 4827 base += n; 4828 size -= n; 4829 n = PAGE_SIZE; 4830 } 4831 } 4832} 4833 4834/* 4835 * Update buffer flags based on I/O request parameters, optionally releasing the 4836 * buffer. If it's VMIO or direct I/O, the buffer pages are released to the VM, 4837 * where they may be placed on a page queue (VMIO) or freed immediately (direct 4838 * I/O). Otherwise the buffer is released to the cache. 4839 */ 4840static void 4841b_io_dismiss(struct buf *bp, int ioflag, bool release) 4842{ 4843 4844 KASSERT((ioflag & IO_NOREUSE) == 0 || (ioflag & IO_VMIO) != 0, 4845 ("buf %p non-VMIO noreuse", bp)); 4846 4847 if ((ioflag & IO_DIRECT) != 0) 4848 bp->b_flags |= B_DIRECT; 4849 if ((ioflag & IO_EXT) != 0) 4850 bp->b_xflags |= BX_ALTDATA; 4851 if ((ioflag & (IO_VMIO | IO_DIRECT)) != 0 && LIST_EMPTY(&bp->b_dep)) { 4852 bp->b_flags |= B_RELBUF; 4853 if ((ioflag & IO_NOREUSE) != 0) 4854 bp->b_flags |= B_NOREUSE; 4855 if (release) 4856 brelse(bp); 4857 } else if (release) 4858 bqrelse(bp); 4859} 4860 4861void 4862vfs_bio_brelse(struct buf *bp, int ioflag) 4863{ 4864 4865 b_io_dismiss(bp, ioflag, true); 4866} 4867 4868void 4869vfs_bio_set_flags(struct buf *bp, int ioflag) 4870{ 4871 4872 b_io_dismiss(bp, ioflag, false); 4873} 4874 4875/* 4876 * vm_hold_load_pages and vm_hold_free_pages get pages into 4877 * a buffers address space. The pages are anonymous and are 4878 * not associated with a file object. 4879 */ 4880static void 4881vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4882{ 4883 vm_offset_t pg; 4884 vm_page_t p; 4885 int index; 4886 4887 BUF_CHECK_MAPPED(bp); 4888 4889 to = round_page(to); 4890 from = round_page(from); 4891 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4892 MPASS((bp->b_flags & B_MAXPHYS) == 0); 4893 KASSERT(to - from <= maxbcachebuf, 4894 ("vm_hold_load_pages too large %p %#jx %#jx %u", 4895 bp, (uintmax_t)from, (uintmax_t)to, maxbcachebuf)); 4896 4897 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 4898 /* 4899 * note: must allocate system pages since blocking here 4900 * could interfere with paging I/O, no matter which 4901 * process we are. 4902 */ 4903 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ | 4904 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT) | 4905 VM_ALLOC_WAITOK); 4906 pmap_qenter(pg, &p, 1); 4907 bp->b_pages[index] = p; 4908 } 4909 bp->b_npages = index; 4910} 4911 4912/* Return pages associated with this buf to the vm system */ 4913static void 4914vm_hold_free_pages(struct buf *bp, int newbsize) 4915{ 4916 vm_offset_t from; 4917 vm_page_t p; 4918 int index, newnpages; 4919 4920 BUF_CHECK_MAPPED(bp); 4921 4922 from = round_page((vm_offset_t)bp->b_data + newbsize); 4923 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4924 if (bp->b_npages > newnpages) 4925 pmap_qremove(from, bp->b_npages - newnpages); 4926 for (index = newnpages; index < bp->b_npages; index++) { 4927 p = bp->b_pages[index]; 4928 bp->b_pages[index] = NULL; 4929 vm_page_unwire_noq(p); 4930 vm_page_free(p); 4931 } 4932 bp->b_npages = newnpages; 4933} 4934 4935/* 4936 * Map an IO request into kernel virtual address space. 4937 * 4938 * All requests are (re)mapped into kernel VA space. 4939 * Notice that we use b_bufsize for the size of the buffer 4940 * to be mapped. b_bcount might be modified by the driver. 4941 * 4942 * Note that even if the caller determines that the address space should 4943 * be valid, a race or a smaller-file mapped into a larger space may 4944 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 4945 * check the return value. 4946 * 4947 * This function only works with pager buffers. 4948 */ 4949int 4950vmapbuf(struct buf *bp, void *uaddr, size_t len, int mapbuf) 4951{ 4952 vm_prot_t prot; 4953 int pidx; 4954 4955 MPASS((bp->b_flags & B_MAXPHYS) != 0); 4956 prot = VM_PROT_READ; 4957 if (bp->b_iocmd == BIO_READ) 4958 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 4959 pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 4960 (vm_offset_t)uaddr, len, prot, bp->b_pages, PBUF_PAGES); 4961 if (pidx < 0) 4962 return (-1); 4963 bp->b_bufsize = len; 4964 bp->b_npages = pidx; 4965 bp->b_offset = ((vm_offset_t)uaddr) & PAGE_MASK; 4966 if (mapbuf || !unmapped_buf_allowed) { 4967 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_pages, pidx); 4968 bp->b_data = bp->b_kvabase + bp->b_offset; 4969 } else 4970 bp->b_data = unmapped_buf; 4971 return (0); 4972} 4973 4974/* 4975 * Free the io map PTEs associated with this IO operation. 4976 * We also invalidate the TLB entries and restore the original b_addr. 4977 * 4978 * This function only works with pager buffers. 4979 */ 4980void 4981vunmapbuf(struct buf *bp) 4982{ 4983 int npages; 4984 4985 npages = bp->b_npages; 4986 if (buf_mapped(bp)) 4987 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 4988 vm_page_unhold_pages(bp->b_pages, npages); 4989 4990 bp->b_data = unmapped_buf; 4991} 4992 4993void 4994bdone(struct buf *bp) 4995{ 4996 struct mtx *mtxp; 4997 4998 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4999 mtx_lock(mtxp); 5000 bp->b_flags |= B_DONE; 5001 wakeup(bp); 5002 mtx_unlock(mtxp); 5003} 5004 5005void 5006bwait(struct buf *bp, u_char pri, const char *wchan) 5007{ 5008 struct mtx *mtxp; 5009 5010 mtxp = mtx_pool_find(mtxpool_sleep, bp); 5011 mtx_lock(mtxp); 5012 while ((bp->b_flags & B_DONE) == 0) 5013 msleep(bp, mtxp, pri, wchan, 0); 5014 mtx_unlock(mtxp); 5015} 5016 5017int 5018bufsync(struct bufobj *bo, int waitfor) 5019{ 5020 5021 return (VOP_FSYNC(bo2vnode(bo), waitfor, curthread)); 5022} 5023 5024void 5025bufstrategy(struct bufobj *bo, struct buf *bp) 5026{ 5027 int i __unused; 5028 struct vnode *vp; 5029 5030 vp = bp->b_vp; 5031 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 5032 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 5033 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 5034 i = VOP_STRATEGY(vp, bp); 5035 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 5036} 5037 5038/* 5039 * Initialize a struct bufobj before use. Memory is assumed zero filled. 5040 */ 5041void 5042bufobj_init(struct bufobj *bo, void *private) 5043{ 5044 static volatile int bufobj_cleanq; 5045 5046 bo->bo_domain = 5047 atomic_fetchadd_int(&bufobj_cleanq, 1) % buf_domains; 5048 rw_init(BO_LOCKPTR(bo), "bufobj interlock"); 5049 bo->bo_private = private; 5050 TAILQ_INIT(&bo->bo_clean.bv_hd); 5051 TAILQ_INIT(&bo->bo_dirty.bv_hd); 5052} 5053 5054void 5055bufobj_wrefl(struct bufobj *bo) 5056{ 5057 5058 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 5059 ASSERT_BO_WLOCKED(bo); 5060 bo->bo_numoutput++; 5061} 5062 5063void 5064bufobj_wref(struct bufobj *bo) 5065{ 5066 5067 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 5068 BO_LOCK(bo); 5069 bo->bo_numoutput++; 5070 BO_UNLOCK(bo); 5071} 5072 5073void 5074bufobj_wdrop(struct bufobj *bo) 5075{ 5076 5077 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 5078 BO_LOCK(bo); 5079 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 5080 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 5081 bo->bo_flag &= ~BO_WWAIT; 5082 wakeup(&bo->bo_numoutput); 5083 } 5084 BO_UNLOCK(bo); 5085} 5086 5087int 5088bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 5089{ 5090 int error; 5091 5092 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 5093 ASSERT_BO_WLOCKED(bo); 5094 error = 0; 5095 while (bo->bo_numoutput) { 5096 bo->bo_flag |= BO_WWAIT; 5097 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo), 5098 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 5099 if (error) 5100 break; 5101 } 5102 return (error); 5103} 5104 5105/* 5106 * Set bio_data or bio_ma for struct bio from the struct buf. 5107 */ 5108void 5109bdata2bio(struct buf *bp, struct bio *bip) 5110{ 5111 5112 if (!buf_mapped(bp)) { 5113 KASSERT(unmapped_buf_allowed, ("unmapped")); 5114 bip->bio_ma = bp->b_pages; 5115 bip->bio_ma_n = bp->b_npages; 5116 bip->bio_data = unmapped_buf; 5117 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 5118 bip->bio_flags |= BIO_UNMAPPED; 5119 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) / 5120 PAGE_SIZE == bp->b_npages, 5121 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset, 5122 (long long)bip->bio_length, bip->bio_ma_n)); 5123 } else { 5124 bip->bio_data = bp->b_data; 5125 bip->bio_ma = NULL; 5126 } 5127} 5128 5129/* 5130 * The MIPS pmap code currently doesn't handle aliased pages. 5131 * The VIPT caches may not handle page aliasing themselves, leading 5132 * to data corruption. 5133 * 5134 * As such, this code makes a system extremely unhappy if said 5135 * system doesn't support unaliasing the above situation in hardware. 5136 * Some "recent" systems (eg some mips24k/mips74k cores) don't enable 5137 * this feature at build time, so it has to be handled in software. 5138 * 5139 * Once the MIPS pmap/cache code grows to support this function on 5140 * earlier chips, it should be flipped back off. 5141 */ 5142#ifdef __mips__ 5143static int buf_pager_relbuf = 1; 5144#else 5145static int buf_pager_relbuf = 0; 5146#endif 5147SYSCTL_INT(_vfs, OID_AUTO, buf_pager_relbuf, CTLFLAG_RWTUN, 5148 &buf_pager_relbuf, 0, 5149 "Make buffer pager release buffers after reading"); 5150 5151/* 5152 * The buffer pager. It uses buffer reads to validate pages. 5153 * 5154 * In contrast to the generic local pager from vm/vnode_pager.c, this 5155 * pager correctly and easily handles volumes where the underlying 5156 * device block size is greater than the machine page size. The 5157 * buffer cache transparently extends the requested page run to be 5158 * aligned at the block boundary, and does the necessary bogus page 5159 * replacements in the addends to avoid obliterating already valid 5160 * pages. 5161 * 5162 * The only non-trivial issue is that the exclusive busy state for 5163 * pages, which is assumed by the vm_pager_getpages() interface, is 5164 * incompatible with the VMIO buffer cache's desire to share-busy the 5165 * pages. This function performs a trivial downgrade of the pages' 5166 * state before reading buffers, and a less trivial upgrade from the 5167 * shared-busy to excl-busy state after the read. 5168 */ 5169int 5170vfs_bio_getpages(struct vnode *vp, vm_page_t *ma, int count, 5171 int *rbehind, int *rahead, vbg_get_lblkno_t get_lblkno, 5172 vbg_get_blksize_t get_blksize) 5173{ 5174 vm_page_t m; 5175 vm_object_t object; 5176 struct buf *bp; 5177 struct mount *mp; 5178 daddr_t lbn, lbnp; 5179 vm_ooffset_t la, lb, poff, poffe; 5180 long bsize; 5181 int bo_bs, br_flags, error, i, pgsin, pgsin_a, pgsin_b; 5182 bool redo, lpart; 5183 5184 object = vp->v_object; 5185 mp = vp->v_mount; 5186 error = 0; 5187 la = IDX_TO_OFF(ma[count - 1]->pindex); 5188 if (la >= object->un_pager.vnp.vnp_size) 5189 return (VM_PAGER_BAD); 5190 5191 /* 5192 * Change the meaning of la from where the last requested page starts 5193 * to where it ends, because that's the end of the requested region 5194 * and the start of the potential read-ahead region. 5195 */ 5196 la += PAGE_SIZE; 5197 lpart = la > object->un_pager.vnp.vnp_size; 5198 bo_bs = get_blksize(vp, get_lblkno(vp, IDX_TO_OFF(ma[0]->pindex))); 5199 5200 /* 5201 * Calculate read-ahead, behind and total pages. 5202 */ 5203 pgsin = count; 5204 lb = IDX_TO_OFF(ma[0]->pindex); 5205 pgsin_b = OFF_TO_IDX(lb - rounddown2(lb, bo_bs)); 5206 pgsin += pgsin_b; 5207 if (rbehind != NULL) 5208 *rbehind = pgsin_b; 5209 pgsin_a = OFF_TO_IDX(roundup2(la, bo_bs) - la); 5210 if (la + IDX_TO_OFF(pgsin_a) >= object->un_pager.vnp.vnp_size) 5211 pgsin_a = OFF_TO_IDX(roundup2(object->un_pager.vnp.vnp_size, 5212 PAGE_SIZE) - la); 5213 pgsin += pgsin_a; 5214 if (rahead != NULL) 5215 *rahead = pgsin_a; 5216 VM_CNT_INC(v_vnodein); 5217 VM_CNT_ADD(v_vnodepgsin, pgsin); 5218 5219 br_flags = (mp != NULL && (mp->mnt_kern_flag & MNTK_UNMAPPED_BUFS) 5220 != 0) ? GB_UNMAPPED : 0; 5221again: 5222 for (i = 0; i < count; i++) { 5223 if (ma[i] != bogus_page) 5224 vm_page_busy_downgrade(ma[i]); 5225 } 5226 5227 lbnp = -1; 5228 for (i = 0; i < count; i++) { 5229 m = ma[i]; 5230 if (m == bogus_page) 5231 continue; 5232 5233 /* 5234 * Pages are shared busy and the object lock is not 5235 * owned, which together allow for the pages' 5236 * invalidation. The racy test for validity avoids 5237 * useless creation of the buffer for the most typical 5238 * case when invalidation is not used in redo or for 5239 * parallel read. The shared->excl upgrade loop at 5240 * the end of the function catches the race in a 5241 * reliable way (protected by the object lock). 5242 */ 5243 if (vm_page_all_valid(m)) 5244 continue; 5245 5246 poff = IDX_TO_OFF(m->pindex); 5247 poffe = MIN(poff + PAGE_SIZE, object->un_pager.vnp.vnp_size); 5248 for (; poff < poffe; poff += bsize) { 5249 lbn = get_lblkno(vp, poff); 5250 if (lbn == lbnp) 5251 goto next_page; 5252 lbnp = lbn; 5253 5254 bsize = get_blksize(vp, lbn); 5255 error = bread_gb(vp, lbn, bsize, curthread->td_ucred, 5256 br_flags, &bp); 5257 if (error != 0) 5258 goto end_pages; 5259 if (bp->b_rcred == curthread->td_ucred) { 5260 crfree(bp->b_rcred); 5261 bp->b_rcred = NOCRED; 5262 } 5263 if (LIST_EMPTY(&bp->b_dep)) { 5264 /* 5265 * Invalidation clears m->valid, but 5266 * may leave B_CACHE flag if the 5267 * buffer existed at the invalidation 5268 * time. In this case, recycle the 5269 * buffer to do real read on next 5270 * bread() after redo. 5271 * 5272 * Otherwise B_RELBUF is not strictly 5273 * necessary, enable to reduce buf 5274 * cache pressure. 5275 */ 5276 if (buf_pager_relbuf || 5277 !vm_page_all_valid(m)) 5278 bp->b_flags |= B_RELBUF; 5279 5280 bp->b_flags &= ~B_NOCACHE; 5281 brelse(bp); 5282 } else { 5283 bqrelse(bp); 5284 } 5285 } 5286 KASSERT(1 /* racy, enable for debugging */ || 5287 vm_page_all_valid(m) || i == count - 1, 5288 ("buf %d %p invalid", i, m)); 5289 if (i == count - 1 && lpart) { 5290 if (!vm_page_none_valid(m) && 5291 !vm_page_all_valid(m)) 5292 vm_page_zero_invalid(m, TRUE); 5293 } 5294next_page:; 5295 } 5296end_pages: 5297 5298 redo = false; 5299 for (i = 0; i < count; i++) { 5300 if (ma[i] == bogus_page) 5301 continue; 5302 if (vm_page_busy_tryupgrade(ma[i]) == 0) { 5303 vm_page_sunbusy(ma[i]); 5304 ma[i] = vm_page_grab_unlocked(object, ma[i]->pindex, 5305 VM_ALLOC_NORMAL); 5306 } 5307 5308 /* 5309 * Since the pages were only sbusy while neither the 5310 * buffer nor the object lock was held by us, or 5311 * reallocated while vm_page_grab() slept for busy 5312 * relinguish, they could have been invalidated. 5313 * Recheck the valid bits and re-read as needed. 5314 * 5315 * Note that the last page is made fully valid in the 5316 * read loop, and partial validity for the page at 5317 * index count - 1 could mean that the page was 5318 * invalidated or removed, so we must restart for 5319 * safety as well. 5320 */ 5321 if (!vm_page_all_valid(ma[i])) 5322 redo = true; 5323 } 5324 if (redo && error == 0) 5325 goto again; 5326 return (error != 0 ? VM_PAGER_ERROR : VM_PAGER_OK); 5327} 5328 5329#include "opt_ddb.h" 5330#ifdef DDB 5331#include <ddb/ddb.h> 5332 5333/* DDB command to show buffer data */ 5334DB_SHOW_COMMAND(buffer, db_show_buffer) 5335{ 5336 /* get args */ 5337 struct buf *bp = (struct buf *)addr; 5338#ifdef FULL_BUF_TRACKING 5339 uint32_t i, j; 5340#endif 5341 5342 if (!have_addr) { 5343 db_printf("usage: show buffer <addr>\n"); 5344 return; 5345 } 5346 5347 db_printf("buf at %p\n", bp); 5348 db_printf("b_flags = 0x%b, b_xflags=0x%b\n", 5349 (u_int)bp->b_flags, PRINT_BUF_FLAGS, 5350 (u_int)bp->b_xflags, PRINT_BUF_XFLAGS); 5351 db_printf("b_vflags=0x%b b_ioflags0x%b\n", 5352 (u_int)bp->b_vflags, PRINT_BUF_VFLAGS, 5353 (u_int)bp->b_ioflags, PRINT_BIO_FLAGS); 5354 db_printf( 5355 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 5356 "b_bufobj = (%p), b_data = %p\n, b_blkno = %jd, b_lblkno = %jd, " 5357 "b_vp = %p, b_dep = %p\n", 5358 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 5359 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 5360 (intmax_t)bp->b_lblkno, bp->b_vp, bp->b_dep.lh_first); 5361 db_printf("b_kvabase = %p, b_kvasize = %d\n", 5362 bp->b_kvabase, bp->b_kvasize); 5363 if (bp->b_npages) { 5364 int i; 5365 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 5366 for (i = 0; i < bp->b_npages; i++) { 5367 vm_page_t m; 5368 m = bp->b_pages[i]; 5369 if (m != NULL) 5370 db_printf("(%p, 0x%lx, 0x%lx)", m->object, 5371 (u_long)m->pindex, 5372 (u_long)VM_PAGE_TO_PHYS(m)); 5373 else 5374 db_printf("( ??? )"); 5375 if ((i + 1) < bp->b_npages) 5376 db_printf(","); 5377 } 5378 db_printf("\n"); 5379 } 5380 BUF_LOCKPRINTINFO(bp); 5381#if defined(FULL_BUF_TRACKING) 5382 db_printf("b_io_tracking: b_io_tcnt = %u\n", bp->b_io_tcnt); 5383 5384 i = bp->b_io_tcnt % BUF_TRACKING_SIZE; 5385 for (j = 1; j <= BUF_TRACKING_SIZE; j++) { 5386 if (bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)] == NULL) 5387 continue; 5388 db_printf(" %2u: %s\n", j, 5389 bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)]); 5390 } 5391#elif defined(BUF_TRACKING) 5392 db_printf("b_io_tracking: %s\n", bp->b_io_tracking); 5393#endif 5394 db_printf(" "); 5395} 5396 5397DB_SHOW_COMMAND(bufqueues, bufqueues) 5398{ 5399 struct bufdomain *bd; 5400 struct buf *bp; 5401 long total; 5402 int i, j, cnt; 5403 5404 db_printf("bqempty: %d\n", bqempty.bq_len); 5405 5406 for (i = 0; i < buf_domains; i++) { 5407 bd = &bdomain[i]; 5408 db_printf("Buf domain %d\n", i); 5409 db_printf("\tfreebufs\t%d\n", bd->bd_freebuffers); 5410 db_printf("\tlofreebufs\t%d\n", bd->bd_lofreebuffers); 5411 db_printf("\thifreebufs\t%d\n", bd->bd_hifreebuffers); 5412 db_printf("\n"); 5413 db_printf("\tbufspace\t%ld\n", bd->bd_bufspace); 5414 db_printf("\tmaxbufspace\t%ld\n", bd->bd_maxbufspace); 5415 db_printf("\thibufspace\t%ld\n", bd->bd_hibufspace); 5416 db_printf("\tlobufspace\t%ld\n", bd->bd_lobufspace); 5417 db_printf("\tbufspacethresh\t%ld\n", bd->bd_bufspacethresh); 5418 db_printf("\n"); 5419 db_printf("\tnumdirtybuffers\t%d\n", bd->bd_numdirtybuffers); 5420 db_printf("\tlodirtybuffers\t%d\n", bd->bd_lodirtybuffers); 5421 db_printf("\thidirtybuffers\t%d\n", bd->bd_hidirtybuffers); 5422 db_printf("\tdirtybufthresh\t%d\n", bd->bd_dirtybufthresh); 5423 db_printf("\n"); 5424 total = 0; 5425 TAILQ_FOREACH(bp, &bd->bd_cleanq->bq_queue, b_freelist) 5426 total += bp->b_bufsize; 5427 db_printf("\tcleanq count\t%d (%ld)\n", 5428 bd->bd_cleanq->bq_len, total); 5429 total = 0; 5430 TAILQ_FOREACH(bp, &bd->bd_dirtyq.bq_queue, b_freelist) 5431 total += bp->b_bufsize; 5432 db_printf("\tdirtyq count\t%d (%ld)\n", 5433 bd->bd_dirtyq.bq_len, total); 5434 db_printf("\twakeup\t\t%d\n", bd->bd_wanted); 5435 db_printf("\tlim\t\t%d\n", bd->bd_lim); 5436 db_printf("\tCPU "); 5437 for (j = 0; j <= mp_maxid; j++) 5438 db_printf("%d, ", bd->bd_subq[j].bq_len); 5439 db_printf("\n"); 5440 cnt = 0; 5441 total = 0; 5442 for (j = 0; j < nbuf; j++) { 5443 bp = nbufp(j); 5444 if (bp->b_domain == i && BUF_ISLOCKED(bp)) { 5445 cnt++; 5446 total += bp->b_bufsize; 5447 } 5448 } 5449 db_printf("\tLocked buffers: %d space %ld\n", cnt, total); 5450 cnt = 0; 5451 total = 0; 5452 for (j = 0; j < nbuf; j++) { 5453 bp = nbufp(j); 5454 if (bp->b_domain == i) { 5455 cnt++; 5456 total += bp->b_bufsize; 5457 } 5458 } 5459 db_printf("\tTotal buffers: %d space %ld\n", cnt, total); 5460 } 5461} 5462 5463DB_SHOW_COMMAND(lockedbufs, lockedbufs) 5464{ 5465 struct buf *bp; 5466 int i; 5467 5468 for (i = 0; i < nbuf; i++) { 5469 bp = nbufp(i); 5470 if (BUF_ISLOCKED(bp)) { 5471 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 5472 db_printf("\n"); 5473 if (db_pager_quit) 5474 break; 5475 } 5476 } 5477} 5478 5479DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 5480{ 5481 struct vnode *vp; 5482 struct buf *bp; 5483 5484 if (!have_addr) { 5485 db_printf("usage: show vnodebufs <addr>\n"); 5486 return; 5487 } 5488 vp = (struct vnode *)addr; 5489 db_printf("Clean buffers:\n"); 5490 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 5491 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 5492 db_printf("\n"); 5493 } 5494 db_printf("Dirty buffers:\n"); 5495 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 5496 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 5497 db_printf("\n"); 5498 } 5499} 5500 5501DB_COMMAND(countfreebufs, db_coundfreebufs) 5502{ 5503 struct buf *bp; 5504 int i, used = 0, nfree = 0; 5505 5506 if (have_addr) { 5507 db_printf("usage: countfreebufs\n"); 5508 return; 5509 } 5510 5511 for (i = 0; i < nbuf; i++) { 5512 bp = nbufp(i); 5513 if (bp->b_qindex == QUEUE_EMPTY) 5514 nfree++; 5515 else 5516 used++; 5517 } 5518 5519 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 5520 nfree + used); 5521 db_printf("numfreebuffers is %d\n", numfreebuffers); 5522} 5523#endif /* DDB */ 5524