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