1 /*- 2 * Copyright (c) 2004 Poul-Henning Kamp 3 * Copyright (c) 1994,1997 John S. Dyson 4 * Copyright (c) 2013 The FreeBSD Foundation 5 * All rights reserved. 6 * 7 * Portions of this software were developed by Konstantin Belousov 8 * under sponsorship from the FreeBSD Foundation. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 /* 33 * this file contains a new buffer I/O scheme implementing a coherent 34 * VM object and buffer cache scheme. Pains have been taken to make 35 * sure that the performance degradation associated with schemes such 36 * as this is not realized. 37 * 38 * Author: John S. Dyson 39 * Significant help during the development and debugging phases 40 * had been provided by David Greenman, also of the FreeBSD core team. 41 * 42 * see man buf(9) for more info. 43 */ 44 45 #include <sys/cdefs.h> 46 __FBSDID("$FreeBSD$"); 47 48 #include <sys/param.h> 49 #include <sys/systm.h> 50 #include <sys/bio.h> 51 #include <sys/conf.h> 52 #include <sys/buf.h> 53 #include <sys/devicestat.h> 54 #include <sys/eventhandler.h> 55 #include <sys/fail.h> 56 #include <sys/limits.h> 57 #include <sys/lock.h> 58 #include <sys/malloc.h> 59 #include <sys/mount.h> 60 #include <sys/mutex.h> 61 #include <sys/kernel.h> 62 #include <sys/kthread.h> 63 #include <sys/proc.h> 64 #include <sys/resourcevar.h> 65 #include <sys/rwlock.h> 66 #include <sys/sysctl.h> 67 #include <sys/sysproto.h> 68 #include <sys/vmem.h> 69 #include <sys/vmmeter.h> 70 #include <sys/vnode.h> 71 #include <sys/watchdog.h> 72 #include <geom/geom.h> 73 #include <vm/vm.h> 74 #include <vm/vm_param.h> 75 #include <vm/vm_kern.h> 76 #include <vm/vm_pageout.h> 77 #include <vm/vm_page.h> 78 #include <vm/vm_object.h> 79 #include <vm/vm_extern.h> 80 #include <vm/vm_map.h> 81 #include <vm/swap_pager.h> 82 #include "opt_compat.h" 83 #include "opt_swap.h" 84 85 static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer"); 86 87 struct bio_ops bioops; /* I/O operation notification */ 88 89 struct buf_ops buf_ops_bio = { 90 .bop_name = "buf_ops_bio", 91 .bop_write = bufwrite, 92 .bop_strategy = bufstrategy, 93 .bop_sync = bufsync, 94 .bop_bdflush = bufbdflush, 95 }; 96 97 static struct buf *buf; /* buffer header pool */ 98 extern struct buf *swbuf; /* Swap buffer header pool. */ 99 caddr_t unmapped_buf; 100 101 /* Used below and for softdep flushing threads in ufs/ffs/ffs_softdep.c */ 102 struct proc *bufdaemonproc; 103 104 static int inmem(struct vnode *vp, daddr_t blkno); 105 static void vm_hold_free_pages(struct buf *bp, int newbsize); 106 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from, 107 vm_offset_t to); 108 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m); 109 static void vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, 110 vm_page_t m); 111 static void vfs_clean_pages_dirty_buf(struct buf *bp); 112 static void vfs_setdirty_locked_object(struct buf *bp); 113 static void vfs_vmio_invalidate(struct buf *bp); 114 static void vfs_vmio_truncate(struct buf *bp, int npages); 115 static void vfs_vmio_extend(struct buf *bp, int npages, int size); 116 static int vfs_bio_clcheck(struct vnode *vp, int size, 117 daddr_t lblkno, daddr_t blkno); 118 static int buf_flush(struct vnode *vp, int); 119 static int flushbufqueues(struct vnode *, int, int); 120 static void buf_daemon(void); 121 static void bremfreel(struct buf *bp); 122 static __inline void bd_wakeup(void); 123 static int sysctl_runningspace(SYSCTL_HANDLER_ARGS); 124 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 125 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 126 static int sysctl_bufspace(SYSCTL_HANDLER_ARGS); 127 #endif 128 129 int vmiodirenable = TRUE; 130 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, 131 "Use the VM system for directory writes"); 132 long runningbufspace; 133 SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 134 "Amount of presently outstanding async buffer io"); 135 static long bufspace; 136 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 137 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 138 SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD, 139 &bufspace, 0, sysctl_bufspace, "L", "Virtual memory used for buffers"); 140 #else 141 SYSCTL_LONG(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, 142 "Physical memory used for buffers"); 143 #endif 144 static long bufkvaspace; 145 SYSCTL_LONG(_vfs, OID_AUTO, bufkvaspace, CTLFLAG_RD, &bufkvaspace, 0, 146 "Kernel virtual memory used for buffers"); 147 static long maxbufspace; 148 SYSCTL_LONG(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0, 149 "Maximum allowed value of bufspace (including buf_daemon)"); 150 static long bufmallocspace; 151 SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 152 "Amount of malloced memory for buffers"); 153 static long maxbufmallocspace; 154 SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0, 155 "Maximum amount of malloced memory for buffers"); 156 static long lobufspace; 157 SYSCTL_LONG(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0, 158 "Minimum amount of buffers we want to have"); 159 long hibufspace; 160 SYSCTL_LONG(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0, 161 "Maximum allowed value of bufspace (excluding buf_daemon)"); 162 static int bufreusecnt; 163 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0, 164 "Number of times we have reused a buffer"); 165 static int buffreekvacnt; 166 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0, 167 "Number of times we have freed the KVA space from some buffer"); 168 static int bufdefragcnt; 169 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0, 170 "Number of times we have had to repeat buffer allocation to defragment"); 171 static long lorunningspace; 172 SYSCTL_PROC(_vfs, OID_AUTO, lorunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE | 173 CTLFLAG_RW, &lorunningspace, 0, sysctl_runningspace, "L", 174 "Minimum preferred space used for in-progress I/O"); 175 static long hirunningspace; 176 SYSCTL_PROC(_vfs, OID_AUTO, hirunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE | 177 CTLFLAG_RW, &hirunningspace, 0, sysctl_runningspace, "L", 178 "Maximum amount of space to use for in-progress I/O"); 179 int dirtybufferflushes; 180 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes, 181 0, "Number of bdwrite to bawrite conversions to limit dirty buffers"); 182 int bdwriteskip; 183 SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip, 184 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk"); 185 int altbufferflushes; 186 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes, 187 0, "Number of fsync flushes to limit dirty buffers"); 188 static int recursiveflushes; 189 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes, 190 0, "Number of flushes skipped due to being recursive"); 191 static int numdirtybuffers; 192 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0, 193 "Number of buffers that are dirty (has unwritten changes) at the moment"); 194 static int lodirtybuffers; 195 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0, 196 "How many buffers we want to have free before bufdaemon can sleep"); 197 static int hidirtybuffers; 198 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0, 199 "When the number of dirty buffers is considered severe"); 200 int dirtybufthresh; 201 SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh, 202 0, "Number of bdwrite to bawrite conversions to clear dirty buffers"); 203 static int numfreebuffers; 204 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, 205 "Number of free buffers"); 206 static int lofreebuffers; 207 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0, 208 "XXX Unused"); 209 static int hifreebuffers; 210 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0, 211 "XXX Complicatedly unused"); 212 static int getnewbufcalls; 213 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0, 214 "Number of calls to getnewbuf"); 215 static int getnewbufrestarts; 216 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0, 217 "Number of times getnewbuf has had to restart a buffer aquisition"); 218 static int mappingrestarts; 219 SYSCTL_INT(_vfs, OID_AUTO, mappingrestarts, CTLFLAG_RW, &mappingrestarts, 0, 220 "Number of times getblk has had to restart a buffer mapping for " 221 "unmapped buffer"); 222 static int flushbufqtarget = 100; 223 SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0, 224 "Amount of work to do in flushbufqueues when helping bufdaemon"); 225 static long notbufdflushes; 226 SYSCTL_LONG(_vfs, OID_AUTO, notbufdflushes, CTLFLAG_RD, ¬bufdflushes, 0, 227 "Number of dirty buffer flushes done by the bufdaemon helpers"); 228 static long barrierwrites; 229 SYSCTL_LONG(_vfs, OID_AUTO, barrierwrites, CTLFLAG_RW, &barrierwrites, 0, 230 "Number of barrier writes"); 231 SYSCTL_INT(_vfs, OID_AUTO, unmapped_buf_allowed, CTLFLAG_RD, 232 &unmapped_buf_allowed, 0, 233 "Permit the use of the unmapped i/o"); 234 235 /* 236 * Lock for the non-dirty bufqueues 237 */ 238 static struct mtx_padalign bqclean; 239 240 /* 241 * Lock for the dirty queue. 242 */ 243 static struct mtx_padalign bqdirty; 244 245 /* 246 * This lock synchronizes access to bd_request. 247 */ 248 static struct mtx_padalign bdlock; 249 250 /* 251 * This lock protects the runningbufreq and synchronizes runningbufwakeup and 252 * waitrunningbufspace(). 253 */ 254 static struct mtx_padalign rbreqlock; 255 256 /* 257 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it. 258 */ 259 static struct rwlock_padalign nblock; 260 261 /* 262 * Lock that protects bdirtywait. 263 */ 264 static struct mtx_padalign bdirtylock; 265 266 /* 267 * Wakeup point for bufdaemon, as well as indicator of whether it is already 268 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it 269 * is idling. 270 */ 271 static int bd_request; 272 273 /* 274 * Request for the buf daemon to write more buffers than is indicated by 275 * lodirtybuf. This may be necessary to push out excess dependencies or 276 * defragment the address space where a simple count of the number of dirty 277 * buffers is insufficient to characterize the demand for flushing them. 278 */ 279 static int bd_speedupreq; 280 281 /* 282 * bogus page -- for I/O to/from partially complete buffers 283 * this is a temporary solution to the problem, but it is not 284 * really that bad. it would be better to split the buffer 285 * for input in the case of buffers partially already in memory, 286 * but the code is intricate enough already. 287 */ 288 vm_page_t bogus_page; 289 290 /* 291 * Synchronization (sleep/wakeup) variable for active buffer space requests. 292 * Set when wait starts, cleared prior to wakeup(). 293 * Used in runningbufwakeup() and waitrunningbufspace(). 294 */ 295 static int runningbufreq; 296 297 /* 298 * Synchronization (sleep/wakeup) variable for buffer requests. 299 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done 300 * by and/or. 301 * Used in numdirtywakeup(), bufspacewakeup(), bufcountadd(), bwillwrite(), 302 * getnewbuf(), and getblk(). 303 */ 304 static volatile int needsbuffer; 305 306 /* 307 * Synchronization for bwillwrite() waiters. 308 */ 309 static int bdirtywait; 310 311 /* 312 * Definitions for the buffer free lists. 313 */ 314 #define BUFFER_QUEUES 4 /* number of free buffer queues */ 315 316 #define QUEUE_NONE 0 /* on no queue */ 317 #define QUEUE_CLEAN 1 /* non-B_DELWRI buffers */ 318 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */ 319 #define QUEUE_EMPTY 3 /* empty buffer headers */ 320 #define QUEUE_SENTINEL 1024 /* not an queue index, but mark for sentinel */ 321 322 /* Queues for free buffers with various properties */ 323 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } }; 324 #ifdef INVARIANTS 325 static int bq_len[BUFFER_QUEUES]; 326 #endif 327 328 /* 329 * Single global constant for BUF_WMESG, to avoid getting multiple references. 330 * buf_wmesg is referred from macros. 331 */ 332 const char *buf_wmesg = BUF_WMESG; 333 334 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 335 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ 336 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 337 338 static int 339 sysctl_runningspace(SYSCTL_HANDLER_ARGS) 340 { 341 long value; 342 int error; 343 344 value = *(long *)arg1; 345 error = sysctl_handle_long(oidp, &value, 0, req); 346 if (error != 0 || req->newptr == NULL) 347 return (error); 348 mtx_lock(&rbreqlock); 349 if (arg1 == &hirunningspace) { 350 if (value < lorunningspace) 351 error = EINVAL; 352 else 353 hirunningspace = value; 354 } else { 355 KASSERT(arg1 == &lorunningspace, 356 ("%s: unknown arg1", __func__)); 357 if (value > hirunningspace) 358 error = EINVAL; 359 else 360 lorunningspace = value; 361 } 362 mtx_unlock(&rbreqlock); 363 return (error); 364 } 365 366 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 367 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 368 static int 369 sysctl_bufspace(SYSCTL_HANDLER_ARGS) 370 { 371 long lvalue; 372 int ivalue; 373 374 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long)) 375 return (sysctl_handle_long(oidp, arg1, arg2, req)); 376 lvalue = *(long *)arg1; 377 if (lvalue > INT_MAX) 378 /* On overflow, still write out a long to trigger ENOMEM. */ 379 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 380 ivalue = lvalue; 381 return (sysctl_handle_int(oidp, &ivalue, 0, req)); 382 } 383 #endif 384 385 /* 386 * bqlock: 387 * 388 * Return the appropriate queue lock based on the index. 389 */ 390 static inline struct mtx * 391 bqlock(int qindex) 392 { 393 394 if (qindex == QUEUE_DIRTY) 395 return (struct mtx *)(&bqdirty); 396 return (struct mtx *)(&bqclean); 397 } 398 399 /* 400 * bdirtywakeup: 401 * 402 * Wakeup any bwillwrite() waiters. 403 */ 404 static void 405 bdirtywakeup(void) 406 { 407 mtx_lock(&bdirtylock); 408 if (bdirtywait) { 409 bdirtywait = 0; 410 wakeup(&bdirtywait); 411 } 412 mtx_unlock(&bdirtylock); 413 } 414 415 /* 416 * bdirtysub: 417 * 418 * Decrement the numdirtybuffers count by one and wakeup any 419 * threads blocked in bwillwrite(). 420 */ 421 static void 422 bdirtysub(void) 423 { 424 425 if (atomic_fetchadd_int(&numdirtybuffers, -1) == 426 (lodirtybuffers + hidirtybuffers) / 2) 427 bdirtywakeup(); 428 } 429 430 /* 431 * bdirtyadd: 432 * 433 * Increment the numdirtybuffers count by one and wakeup the buf 434 * daemon if needed. 435 */ 436 static void 437 bdirtyadd(void) 438 { 439 440 /* 441 * Only do the wakeup once as we cross the boundary. The 442 * buf daemon will keep running until the condition clears. 443 */ 444 if (atomic_fetchadd_int(&numdirtybuffers, 1) == 445 (lodirtybuffers + hidirtybuffers) / 2) 446 bd_wakeup(); 447 } 448 449 /* 450 * bufspacewakeup: 451 * 452 * Called when buffer space is potentially available for recovery. 453 * getnewbuf() will block on this flag when it is unable to free 454 * sufficient buffer space. Buffer space becomes recoverable when 455 * bp's get placed back in the queues. 456 */ 457 static __inline void 458 bufspacewakeup(void) 459 { 460 int need_wakeup, on; 461 462 /* 463 * If someone is waiting for bufspace, wake them up. Even 464 * though we may not have freed the kva space yet, the waiting 465 * process will be able to now. 466 */ 467 rw_rlock(&nblock); 468 for (;;) { 469 need_wakeup = 0; 470 on = needsbuffer; 471 if ((on & VFS_BIO_NEED_BUFSPACE) == 0) 472 break; 473 need_wakeup = 1; 474 if (atomic_cmpset_rel_int(&needsbuffer, on, 475 on & ~VFS_BIO_NEED_BUFSPACE)) 476 break; 477 } 478 if (need_wakeup) 479 wakeup(__DEVOLATILE(void *, &needsbuffer)); 480 rw_runlock(&nblock); 481 } 482 483 /* 484 * bufspaceadjust: 485 * 486 * Adjust the reported bufspace for a KVA managed buffer, possibly 487 * waking any waiters. 488 */ 489 static void 490 bufspaceadjust(struct buf *bp, int bufsize) 491 { 492 int diff; 493 494 KASSERT((bp->b_flags & B_MALLOC) == 0, 495 ("bufspaceadjust: malloc buf %p", bp)); 496 diff = bufsize - bp->b_bufsize; 497 if (diff < 0) { 498 atomic_subtract_long(&bufspace, -diff); 499 bufspacewakeup(); 500 } else 501 atomic_add_long(&bufspace, diff); 502 bp->b_bufsize = bufsize; 503 } 504 505 /* 506 * bufmallocadjust: 507 * 508 * Adjust the reported bufspace for a malloc managed buffer, possibly 509 * waking any waiters. 510 */ 511 static void 512 bufmallocadjust(struct buf *bp, int bufsize) 513 { 514 int diff; 515 516 KASSERT((bp->b_flags & B_MALLOC) != 0, 517 ("bufmallocadjust: non-malloc buf %p", bp)); 518 diff = bufsize - bp->b_bufsize; 519 if (diff < 0) { 520 atomic_subtract_long(&bufmallocspace, -diff); 521 bufspacewakeup(); 522 } else 523 atomic_add_long(&bufmallocspace, diff); 524 bp->b_bufsize = bufsize; 525 } 526 527 /* 528 * runningwakeup: 529 * 530 * Wake up processes that are waiting on asynchronous writes to fall 531 * below lorunningspace. 532 */ 533 static void 534 runningwakeup(void) 535 { 536 537 mtx_lock(&rbreqlock); 538 if (runningbufreq) { 539 runningbufreq = 0; 540 wakeup(&runningbufreq); 541 } 542 mtx_unlock(&rbreqlock); 543 } 544 545 /* 546 * runningbufwakeup: 547 * 548 * Decrement the outstanding write count according. 549 */ 550 void 551 runningbufwakeup(struct buf *bp) 552 { 553 long space, bspace; 554 555 bspace = bp->b_runningbufspace; 556 if (bspace == 0) 557 return; 558 space = atomic_fetchadd_long(&runningbufspace, -bspace); 559 KASSERT(space >= bspace, ("runningbufspace underflow %ld %ld", 560 space, bspace)); 561 bp->b_runningbufspace = 0; 562 /* 563 * Only acquire the lock and wakeup on the transition from exceeding 564 * the threshold to falling below it. 565 */ 566 if (space < lorunningspace) 567 return; 568 if (space - bspace > lorunningspace) 569 return; 570 runningwakeup(); 571 } 572 573 /* 574 * bufcountadd: 575 * 576 * Called when a buffer has been added to one of the free queues to 577 * account for the buffer and to wakeup anyone waiting for free buffers. 578 * This typically occurs when large amounts of metadata are being handled 579 * by the buffer cache ( else buffer space runs out first, usually ). 580 */ 581 static __inline void 582 bufcountadd(struct buf *bp) 583 { 584 int mask, need_wakeup, old, on; 585 586 KASSERT((bp->b_flags & B_INFREECNT) == 0, 587 ("buf %p already counted as free", bp)); 588 bp->b_flags |= B_INFREECNT; 589 old = atomic_fetchadd_int(&numfreebuffers, 1); 590 KASSERT(old >= 0 && old < nbuf, 591 ("numfreebuffers climbed to %d", old + 1)); 592 mask = VFS_BIO_NEED_ANY; 593 if (numfreebuffers >= hifreebuffers) 594 mask |= VFS_BIO_NEED_FREE; 595 rw_rlock(&nblock); 596 for (;;) { 597 need_wakeup = 0; 598 on = needsbuffer; 599 if (on == 0) 600 break; 601 need_wakeup = 1; 602 if (atomic_cmpset_rel_int(&needsbuffer, on, on & ~mask)) 603 break; 604 } 605 if (need_wakeup) 606 wakeup(__DEVOLATILE(void *, &needsbuffer)); 607 rw_runlock(&nblock); 608 } 609 610 /* 611 * bufcountsub: 612 * 613 * Decrement the numfreebuffers count as needed. 614 */ 615 static void 616 bufcountsub(struct buf *bp) 617 { 618 int old; 619 620 /* 621 * Fixup numfreebuffers count. If the buffer is invalid or not 622 * delayed-write, the buffer was free and we must decrement 623 * numfreebuffers. 624 */ 625 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { 626 KASSERT((bp->b_flags & B_INFREECNT) != 0, 627 ("buf %p not counted in numfreebuffers", bp)); 628 bp->b_flags &= ~B_INFREECNT; 629 old = atomic_fetchadd_int(&numfreebuffers, -1); 630 KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1)); 631 } 632 } 633 634 /* 635 * waitrunningbufspace() 636 * 637 * runningbufspace is a measure of the amount of I/O currently 638 * running. This routine is used in async-write situations to 639 * prevent creating huge backups of pending writes to a device. 640 * Only asynchronous writes are governed by this function. 641 * 642 * This does NOT turn an async write into a sync write. It waits 643 * for earlier writes to complete and generally returns before the 644 * caller's write has reached the device. 645 */ 646 void 647 waitrunningbufspace(void) 648 { 649 650 mtx_lock(&rbreqlock); 651 while (runningbufspace > hirunningspace) { 652 runningbufreq = 1; 653 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 654 } 655 mtx_unlock(&rbreqlock); 656 } 657 658 659 /* 660 * vfs_buf_test_cache: 661 * 662 * Called when a buffer is extended. This function clears the B_CACHE 663 * bit if the newly extended portion of the buffer does not contain 664 * valid data. 665 */ 666 static __inline void 667 vfs_buf_test_cache(struct buf *bp, vm_ooffset_t foff, vm_offset_t off, 668 vm_offset_t size, vm_page_t m) 669 { 670 671 VM_OBJECT_ASSERT_LOCKED(m->object); 672 if (bp->b_flags & B_CACHE) { 673 int base = (foff + off) & PAGE_MASK; 674 if (vm_page_is_valid(m, base, size) == 0) 675 bp->b_flags &= ~B_CACHE; 676 } 677 } 678 679 /* Wake up the buffer daemon if necessary */ 680 static __inline void 681 bd_wakeup(void) 682 { 683 684 mtx_lock(&bdlock); 685 if (bd_request == 0) { 686 bd_request = 1; 687 wakeup(&bd_request); 688 } 689 mtx_unlock(&bdlock); 690 } 691 692 /* 693 * bd_speedup - speedup the buffer cache flushing code 694 */ 695 void 696 bd_speedup(void) 697 { 698 int needwake; 699 700 mtx_lock(&bdlock); 701 needwake = 0; 702 if (bd_speedupreq == 0 || bd_request == 0) 703 needwake = 1; 704 bd_speedupreq = 1; 705 bd_request = 1; 706 if (needwake) 707 wakeup(&bd_request); 708 mtx_unlock(&bdlock); 709 } 710 711 #ifndef NSWBUF_MIN 712 #define NSWBUF_MIN 16 713 #endif 714 715 #ifdef __i386__ 716 #define TRANSIENT_DENOM 5 717 #else 718 #define TRANSIENT_DENOM 10 719 #endif 720 721 /* 722 * Calculating buffer cache scaling values and reserve space for buffer 723 * headers. This is called during low level kernel initialization and 724 * may be called more then once. We CANNOT write to the memory area 725 * being reserved at this time. 726 */ 727 caddr_t 728 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 729 { 730 int tuned_nbuf; 731 long maxbuf, maxbuf_sz, buf_sz, biotmap_sz; 732 733 /* 734 * physmem_est is in pages. Convert it to kilobytes (assumes 735 * PAGE_SIZE is >= 1K) 736 */ 737 physmem_est = physmem_est * (PAGE_SIZE / 1024); 738 739 /* 740 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 741 * For the first 64MB of ram nominally allocate sufficient buffers to 742 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 743 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing 744 * the buffer cache we limit the eventual kva reservation to 745 * maxbcache bytes. 746 * 747 * factor represents the 1/4 x ram conversion. 748 */ 749 if (nbuf == 0) { 750 int factor = 4 * BKVASIZE / 1024; 751 752 nbuf = 50; 753 if (physmem_est > 4096) 754 nbuf += min((physmem_est - 4096) / factor, 755 65536 / factor); 756 if (physmem_est > 65536) 757 nbuf += min((physmem_est - 65536) * 2 / (factor * 5), 758 32 * 1024 * 1024 / (factor * 5)); 759 760 if (maxbcache && nbuf > maxbcache / BKVASIZE) 761 nbuf = maxbcache / BKVASIZE; 762 tuned_nbuf = 1; 763 } else 764 tuned_nbuf = 0; 765 766 /* XXX Avoid unsigned long overflows later on with maxbufspace. */ 767 maxbuf = (LONG_MAX / 3) / BKVASIZE; 768 if (nbuf > maxbuf) { 769 if (!tuned_nbuf) 770 printf("Warning: nbufs lowered from %d to %ld\n", nbuf, 771 maxbuf); 772 nbuf = maxbuf; 773 } 774 775 /* 776 * Ideal allocation size for the transient bio submap is 10% 777 * of the maximal space buffer map. This roughly corresponds 778 * to the amount of the buffer mapped for typical UFS load. 779 * 780 * Clip the buffer map to reserve space for the transient 781 * BIOs, if its extent is bigger than 90% (80% on i386) of the 782 * maximum buffer map extent on the platform. 783 * 784 * The fall-back to the maxbuf in case of maxbcache unset, 785 * allows to not trim the buffer KVA for the architectures 786 * with ample KVA space. 787 */ 788 if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) { 789 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE; 790 buf_sz = (long)nbuf * BKVASIZE; 791 if (buf_sz < maxbuf_sz / TRANSIENT_DENOM * 792 (TRANSIENT_DENOM - 1)) { 793 /* 794 * There is more KVA than memory. Do not 795 * adjust buffer map size, and assign the rest 796 * of maxbuf to transient map. 797 */ 798 biotmap_sz = maxbuf_sz - buf_sz; 799 } else { 800 /* 801 * Buffer map spans all KVA we could afford on 802 * this platform. Give 10% (20% on i386) of 803 * the buffer map to the transient bio map. 804 */ 805 biotmap_sz = buf_sz / TRANSIENT_DENOM; 806 buf_sz -= biotmap_sz; 807 } 808 if (biotmap_sz / INT_MAX > MAXPHYS) 809 bio_transient_maxcnt = INT_MAX; 810 else 811 bio_transient_maxcnt = biotmap_sz / MAXPHYS; 812 /* 813 * Artifically limit to 1024 simultaneous in-flight I/Os 814 * using the transient mapping. 815 */ 816 if (bio_transient_maxcnt > 1024) 817 bio_transient_maxcnt = 1024; 818 if (tuned_nbuf) 819 nbuf = buf_sz / BKVASIZE; 820 } 821 822 /* 823 * swbufs are used as temporary holders for I/O, such as paging I/O. 824 * We have no less then 16 and no more then 256. 825 */ 826 nswbuf = min(nbuf / 4, 256); 827 TUNABLE_INT_FETCH("kern.nswbuf", &nswbuf); 828 if (nswbuf < NSWBUF_MIN) 829 nswbuf = NSWBUF_MIN; 830 831 /* 832 * Reserve space for the buffer cache buffers 833 */ 834 swbuf = (void *)v; 835 v = (caddr_t)(swbuf + nswbuf); 836 buf = (void *)v; 837 v = (caddr_t)(buf + nbuf); 838 839 return(v); 840 } 841 842 /* Initialize the buffer subsystem. Called before use of any buffers. */ 843 void 844 bufinit(void) 845 { 846 struct buf *bp; 847 int i; 848 849 CTASSERT(MAXBCACHEBUF >= MAXBSIZE); 850 mtx_init(&bqclean, "bufq clean lock", NULL, MTX_DEF); 851 mtx_init(&bqdirty, "bufq dirty lock", NULL, MTX_DEF); 852 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 853 rw_init(&nblock, "needsbuffer lock"); 854 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 855 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF); 856 857 /* next, make a null set of free lists */ 858 for (i = 0; i < BUFFER_QUEUES; i++) 859 TAILQ_INIT(&bufqueues[i]); 860 861 unmapped_buf = (caddr_t)kva_alloc(MAXPHYS); 862 863 /* finally, initialize each buffer header and stick on empty q */ 864 for (i = 0; i < nbuf; i++) { 865 bp = &buf[i]; 866 bzero(bp, sizeof *bp); 867 bp->b_flags = B_INVAL | B_INFREECNT; 868 bp->b_rcred = NOCRED; 869 bp->b_wcred = NOCRED; 870 bp->b_qindex = QUEUE_EMPTY; 871 bp->b_xflags = 0; 872 bp->b_data = bp->b_kvabase = unmapped_buf; 873 LIST_INIT(&bp->b_dep); 874 BUF_LOCKINIT(bp); 875 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 876 #ifdef INVARIANTS 877 bq_len[QUEUE_EMPTY]++; 878 #endif 879 } 880 881 /* 882 * maxbufspace is the absolute maximum amount of buffer space we are 883 * allowed to reserve in KVM and in real terms. The absolute maximum 884 * is nominally used by buf_daemon. hibufspace is the nominal maximum 885 * used by most other processes. The differential is required to 886 * ensure that buf_daemon is able to run when other processes might 887 * be blocked waiting for buffer space. 888 * 889 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 890 * this may result in KVM fragmentation which is not handled optimally 891 * by the system. 892 */ 893 maxbufspace = (long)nbuf * BKVASIZE; 894 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - MAXBCACHEBUF * 10); 895 lobufspace = hibufspace - MAXBCACHEBUF; 896 897 /* 898 * Note: The 16 MiB upper limit for hirunningspace was chosen 899 * arbitrarily and may need further tuning. It corresponds to 900 * 128 outstanding write IO requests (if IO size is 128 KiB), 901 * which fits with many RAID controllers' tagged queuing limits. 902 * The lower 1 MiB limit is the historical upper limit for 903 * hirunningspace. 904 */ 905 hirunningspace = lmax(lmin(roundup(hibufspace / 64, MAXBCACHEBUF), 906 16 * 1024 * 1024), 1024 * 1024); 907 lorunningspace = roundup((hirunningspace * 2) / 3, MAXBCACHEBUF); 908 909 /* 910 * Limit the amount of malloc memory since it is wired permanently into 911 * the kernel space. Even though this is accounted for in the buffer 912 * allocation, we don't want the malloced region to grow uncontrolled. 913 * The malloc scheme improves memory utilization significantly on average 914 * (small) directories. 915 */ 916 maxbufmallocspace = hibufspace / 20; 917 918 /* 919 * Reduce the chance of a deadlock occuring by limiting the number 920 * of delayed-write dirty buffers we allow to stack up. 921 */ 922 hidirtybuffers = nbuf / 4 + 20; 923 dirtybufthresh = hidirtybuffers * 9 / 10; 924 numdirtybuffers = 0; 925 /* 926 * To support extreme low-memory systems, make sure hidirtybuffers cannot 927 * eat up all available buffer space. This occurs when our minimum cannot 928 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 929 * BKVASIZE'd buffers. 930 */ 931 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 932 hidirtybuffers >>= 1; 933 } 934 lodirtybuffers = hidirtybuffers / 2; 935 936 /* 937 * Try to keep the number of free buffers in the specified range, 938 * and give special processes (e.g. like buf_daemon) access to an 939 * emergency reserve. 940 */ 941 lofreebuffers = nbuf / 18 + 5; 942 hifreebuffers = 2 * lofreebuffers; 943 numfreebuffers = nbuf; 944 945 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ | 946 VM_ALLOC_NORMAL | VM_ALLOC_WIRED); 947 } 948 949 #ifdef INVARIANTS 950 static inline void 951 vfs_buf_check_mapped(struct buf *bp) 952 { 953 954 KASSERT(bp->b_kvabase != unmapped_buf, 955 ("mapped buf: b_kvabase was not updated %p", bp)); 956 KASSERT(bp->b_data != unmapped_buf, 957 ("mapped buf: b_data was not updated %p", bp)); 958 KASSERT(bp->b_data < unmapped_buf || bp->b_data >= unmapped_buf + 959 MAXPHYS, ("b_data + b_offset unmapped %p", bp)); 960 } 961 962 static inline void 963 vfs_buf_check_unmapped(struct buf *bp) 964 { 965 966 KASSERT(bp->b_data == unmapped_buf, 967 ("unmapped buf: corrupted b_data %p", bp)); 968 } 969 970 #define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp) 971 #define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp) 972 #else 973 #define BUF_CHECK_MAPPED(bp) do {} while (0) 974 #define BUF_CHECK_UNMAPPED(bp) do {} while (0) 975 #endif 976 977 static int 978 isbufbusy(struct buf *bp) 979 { 980 if (((bp->b_flags & (B_INVAL | B_PERSISTENT)) == 0 && 981 BUF_ISLOCKED(bp)) || 982 ((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI)) 983 return (1); 984 return (0); 985 } 986 987 /* 988 * Shutdown the system cleanly to prepare for reboot, halt, or power off. 989 */ 990 void 991 bufshutdown(int show_busybufs) 992 { 993 static int first_buf_printf = 1; 994 struct buf *bp; 995 int iter, nbusy, pbusy; 996 #ifndef PREEMPTION 997 int subiter; 998 #endif 999 1000 /* 1001 * Sync filesystems for shutdown 1002 */ 1003 wdog_kern_pat(WD_LASTVAL); 1004 sys_sync(curthread, NULL); 1005 1006 /* 1007 * With soft updates, some buffers that are 1008 * written will be remarked as dirty until other 1009 * buffers are written. 1010 */ 1011 for (iter = pbusy = 0; iter < 20; iter++) { 1012 nbusy = 0; 1013 for (bp = &buf[nbuf]; --bp >= buf; ) 1014 if (isbufbusy(bp)) 1015 nbusy++; 1016 if (nbusy == 0) { 1017 if (first_buf_printf) 1018 printf("All buffers synced."); 1019 break; 1020 } 1021 if (first_buf_printf) { 1022 printf("Syncing disks, buffers remaining... "); 1023 first_buf_printf = 0; 1024 } 1025 printf("%d ", nbusy); 1026 if (nbusy < pbusy) 1027 iter = 0; 1028 pbusy = nbusy; 1029 1030 wdog_kern_pat(WD_LASTVAL); 1031 sys_sync(curthread, NULL); 1032 1033 #ifdef PREEMPTION 1034 /* 1035 * Drop Giant and spin for a while to allow 1036 * interrupt threads to run. 1037 */ 1038 DROP_GIANT(); 1039 DELAY(50000 * iter); 1040 PICKUP_GIANT(); 1041 #else 1042 /* 1043 * Drop Giant and context switch several times to 1044 * allow interrupt threads to run. 1045 */ 1046 DROP_GIANT(); 1047 for (subiter = 0; subiter < 50 * iter; subiter++) { 1048 thread_lock(curthread); 1049 mi_switch(SW_VOL, NULL); 1050 thread_unlock(curthread); 1051 DELAY(1000); 1052 } 1053 PICKUP_GIANT(); 1054 #endif 1055 } 1056 printf("\n"); 1057 /* 1058 * Count only busy local buffers to prevent forcing 1059 * a fsck if we're just a client of a wedged NFS server 1060 */ 1061 nbusy = 0; 1062 for (bp = &buf[nbuf]; --bp >= buf; ) { 1063 if (isbufbusy(bp)) { 1064 #if 0 1065 /* XXX: This is bogus. We should probably have a BO_REMOTE flag instead */ 1066 if (bp->b_dev == NULL) { 1067 TAILQ_REMOVE(&mountlist, 1068 bp->b_vp->v_mount, mnt_list); 1069 continue; 1070 } 1071 #endif 1072 nbusy++; 1073 if (show_busybufs > 0) { 1074 printf( 1075 "%d: buf:%p, vnode:%p, flags:%0x, blkno:%jd, lblkno:%jd, buflock:", 1076 nbusy, bp, bp->b_vp, bp->b_flags, 1077 (intmax_t)bp->b_blkno, 1078 (intmax_t)bp->b_lblkno); 1079 BUF_LOCKPRINTINFO(bp); 1080 if (show_busybufs > 1) 1081 vn_printf(bp->b_vp, 1082 "vnode content: "); 1083 } 1084 } 1085 } 1086 if (nbusy) { 1087 /* 1088 * Failed to sync all blocks. Indicate this and don't 1089 * unmount filesystems (thus forcing an fsck on reboot). 1090 */ 1091 printf("Giving up on %d buffers\n", nbusy); 1092 DELAY(5000000); /* 5 seconds */ 1093 } else { 1094 if (!first_buf_printf) 1095 printf("Final sync complete\n"); 1096 /* 1097 * Unmount filesystems 1098 */ 1099 if (panicstr == 0) 1100 vfs_unmountall(); 1101 } 1102 swapoff_all(); 1103 DELAY(100000); /* wait for console output to finish */ 1104 } 1105 1106 static void 1107 bpmap_qenter(struct buf *bp) 1108 { 1109 1110 BUF_CHECK_MAPPED(bp); 1111 1112 /* 1113 * bp->b_data is relative to bp->b_offset, but 1114 * bp->b_offset may be offset into the first page. 1115 */ 1116 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data); 1117 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages); 1118 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 1119 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 1120 } 1121 1122 /* 1123 * binsfree: 1124 * 1125 * Insert the buffer into the appropriate free list. 1126 */ 1127 static void 1128 binsfree(struct buf *bp, int qindex) 1129 { 1130 struct mtx *olock, *nlock; 1131 1132 BUF_ASSERT_XLOCKED(bp); 1133 1134 nlock = bqlock(qindex); 1135 /* Handle delayed bremfree() processing. */ 1136 if (bp->b_flags & B_REMFREE) { 1137 olock = bqlock(bp->b_qindex); 1138 mtx_lock(olock); 1139 bremfreel(bp); 1140 if (olock != nlock) { 1141 mtx_unlock(olock); 1142 mtx_lock(nlock); 1143 } 1144 } else 1145 mtx_lock(nlock); 1146 1147 if (bp->b_qindex != QUEUE_NONE) 1148 panic("binsfree: free buffer onto another queue???"); 1149 1150 bp->b_qindex = qindex; 1151 if (bp->b_flags & B_AGE) 1152 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1153 else 1154 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1155 #ifdef INVARIANTS 1156 bq_len[bp->b_qindex]++; 1157 #endif 1158 mtx_unlock(nlock); 1159 1160 /* 1161 * Something we can maybe free or reuse. 1162 */ 1163 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1164 bufspacewakeup(); 1165 1166 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI)) 1167 bufcountadd(bp); 1168 } 1169 1170 /* 1171 * bremfree: 1172 * 1173 * Mark the buffer for removal from the appropriate free list. 1174 * 1175 */ 1176 void 1177 bremfree(struct buf *bp) 1178 { 1179 1180 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1181 KASSERT((bp->b_flags & B_REMFREE) == 0, 1182 ("bremfree: buffer %p already marked for delayed removal.", bp)); 1183 KASSERT(bp->b_qindex != QUEUE_NONE, 1184 ("bremfree: buffer %p not on a queue.", bp)); 1185 BUF_ASSERT_XLOCKED(bp); 1186 1187 bp->b_flags |= B_REMFREE; 1188 bufcountsub(bp); 1189 } 1190 1191 /* 1192 * bremfreef: 1193 * 1194 * Force an immediate removal from a free list. Used only in nfs when 1195 * it abuses the b_freelist pointer. 1196 */ 1197 void 1198 bremfreef(struct buf *bp) 1199 { 1200 struct mtx *qlock; 1201 1202 qlock = bqlock(bp->b_qindex); 1203 mtx_lock(qlock); 1204 bremfreel(bp); 1205 mtx_unlock(qlock); 1206 } 1207 1208 /* 1209 * bremfreel: 1210 * 1211 * Removes a buffer from the free list, must be called with the 1212 * correct qlock held. 1213 */ 1214 static void 1215 bremfreel(struct buf *bp) 1216 { 1217 1218 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X", 1219 bp, bp->b_vp, bp->b_flags); 1220 KASSERT(bp->b_qindex != QUEUE_NONE, 1221 ("bremfreel: buffer %p not on a queue.", bp)); 1222 BUF_ASSERT_XLOCKED(bp); 1223 mtx_assert(bqlock(bp->b_qindex), MA_OWNED); 1224 1225 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 1226 #ifdef INVARIANTS 1227 KASSERT(bq_len[bp->b_qindex] >= 1, ("queue %d underflow", 1228 bp->b_qindex)); 1229 bq_len[bp->b_qindex]--; 1230 #endif 1231 bp->b_qindex = QUEUE_NONE; 1232 /* 1233 * If this was a delayed bremfree() we only need to remove the buffer 1234 * from the queue and return the stats are already done. 1235 */ 1236 if (bp->b_flags & B_REMFREE) { 1237 bp->b_flags &= ~B_REMFREE; 1238 return; 1239 } 1240 bufcountsub(bp); 1241 } 1242 1243 /* 1244 * bufkvafree: 1245 * 1246 * Free the kva allocation for a buffer. 1247 * 1248 */ 1249 static void 1250 bufkvafree(struct buf *bp) 1251 { 1252 1253 #ifdef INVARIANTS 1254 if (bp->b_kvasize == 0) { 1255 KASSERT(bp->b_kvabase == unmapped_buf && 1256 bp->b_data == unmapped_buf, 1257 ("Leaked KVA space on %p", bp)); 1258 } else if (buf_mapped(bp)) 1259 BUF_CHECK_MAPPED(bp); 1260 else 1261 BUF_CHECK_UNMAPPED(bp); 1262 #endif 1263 if (bp->b_kvasize == 0) 1264 return; 1265 1266 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, bp->b_kvasize); 1267 atomic_subtract_long(&bufkvaspace, bp->b_kvasize); 1268 atomic_add_int(&buffreekvacnt, 1); 1269 bp->b_data = bp->b_kvabase = unmapped_buf; 1270 bp->b_kvasize = 0; 1271 } 1272 1273 /* 1274 * bufkvaalloc: 1275 * 1276 * Allocate the buffer KVA and set b_kvasize and b_kvabase. 1277 */ 1278 static int 1279 bufkvaalloc(struct buf *bp, int maxsize, int gbflags) 1280 { 1281 vm_offset_t addr; 1282 int error; 1283 1284 KASSERT((gbflags & GB_UNMAPPED) == 0 || (gbflags & GB_KVAALLOC) != 0, 1285 ("Invalid gbflags 0x%x in %s", gbflags, __func__)); 1286 1287 bufkvafree(bp); 1288 1289 addr = 0; 1290 error = vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr); 1291 if (error != 0) { 1292 /* 1293 * Buffer map is too fragmented. Request the caller 1294 * to defragment the map. 1295 */ 1296 atomic_add_int(&bufdefragcnt, 1); 1297 return (error); 1298 } 1299 bp->b_kvabase = (caddr_t)addr; 1300 bp->b_kvasize = maxsize; 1301 atomic_add_long(&bufkvaspace, bp->b_kvasize); 1302 if ((gbflags & GB_UNMAPPED) != 0) { 1303 bp->b_data = unmapped_buf; 1304 BUF_CHECK_UNMAPPED(bp); 1305 } else { 1306 bp->b_data = bp->b_kvabase; 1307 BUF_CHECK_MAPPED(bp); 1308 } 1309 return (0); 1310 } 1311 1312 /* 1313 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 1314 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 1315 * the buffer is valid and we do not have to do anything. 1316 */ 1317 void 1318 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, 1319 int cnt, struct ucred * cred) 1320 { 1321 struct buf *rabp; 1322 int i; 1323 1324 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 1325 if (inmem(vp, *rablkno)) 1326 continue; 1327 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 1328 1329 if ((rabp->b_flags & B_CACHE) == 0) { 1330 if (!TD_IS_IDLETHREAD(curthread)) 1331 curthread->td_ru.ru_inblock++; 1332 rabp->b_flags |= B_ASYNC; 1333 rabp->b_flags &= ~B_INVAL; 1334 rabp->b_ioflags &= ~BIO_ERROR; 1335 rabp->b_iocmd = BIO_READ; 1336 if (rabp->b_rcred == NOCRED && cred != NOCRED) 1337 rabp->b_rcred = crhold(cred); 1338 vfs_busy_pages(rabp, 0); 1339 BUF_KERNPROC(rabp); 1340 rabp->b_iooffset = dbtob(rabp->b_blkno); 1341 bstrategy(rabp); 1342 } else { 1343 brelse(rabp); 1344 } 1345 } 1346 } 1347 1348 /* 1349 * Entry point for bread() and breadn() via #defines in sys/buf.h. 1350 * 1351 * Get a buffer with the specified data. Look in the cache first. We 1352 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 1353 * is set, the buffer is valid and we do not have to do anything, see 1354 * getblk(). Also starts asynchronous I/O on read-ahead blocks. 1355 */ 1356 int 1357 breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno, 1358 int *rabsize, int cnt, struct ucred *cred, int flags, struct buf **bpp) 1359 { 1360 struct buf *bp; 1361 int rv = 0, readwait = 0; 1362 1363 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 1364 /* 1365 * Can only return NULL if GB_LOCK_NOWAIT flag is specified. 1366 */ 1367 *bpp = bp = getblk(vp, blkno, size, 0, 0, flags); 1368 if (bp == NULL) 1369 return (EBUSY); 1370 1371 /* if not found in cache, do some I/O */ 1372 if ((bp->b_flags & B_CACHE) == 0) { 1373 if (!TD_IS_IDLETHREAD(curthread)) 1374 curthread->td_ru.ru_inblock++; 1375 bp->b_iocmd = BIO_READ; 1376 bp->b_flags &= ~B_INVAL; 1377 bp->b_ioflags &= ~BIO_ERROR; 1378 if (bp->b_rcred == NOCRED && cred != NOCRED) 1379 bp->b_rcred = crhold(cred); 1380 vfs_busy_pages(bp, 0); 1381 bp->b_iooffset = dbtob(bp->b_blkno); 1382 bstrategy(bp); 1383 ++readwait; 1384 } 1385 1386 breada(vp, rablkno, rabsize, cnt, cred); 1387 1388 if (readwait) { 1389 rv = bufwait(bp); 1390 } 1391 return (rv); 1392 } 1393 1394 /* 1395 * Write, release buffer on completion. (Done by iodone 1396 * if async). Do not bother writing anything if the buffer 1397 * is invalid. 1398 * 1399 * Note that we set B_CACHE here, indicating that buffer is 1400 * fully valid and thus cacheable. This is true even of NFS 1401 * now so we set it generally. This could be set either here 1402 * or in biodone() since the I/O is synchronous. We put it 1403 * here. 1404 */ 1405 int 1406 bufwrite(struct buf *bp) 1407 { 1408 int oldflags; 1409 struct vnode *vp; 1410 long space; 1411 int vp_md; 1412 1413 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1414 if ((bp->b_bufobj->bo_flag & BO_DEAD) != 0) { 1415 bp->b_flags |= B_INVAL | B_RELBUF; 1416 bp->b_flags &= ~B_CACHE; 1417 brelse(bp); 1418 return (ENXIO); 1419 } 1420 if (bp->b_flags & B_INVAL) { 1421 brelse(bp); 1422 return (0); 1423 } 1424 1425 if (bp->b_flags & B_BARRIER) 1426 barrierwrites++; 1427 1428 oldflags = bp->b_flags; 1429 1430 BUF_ASSERT_HELD(bp); 1431 1432 if (bp->b_pin_count > 0) 1433 bunpin_wait(bp); 1434 1435 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 1436 ("FFS background buffer should not get here %p", bp)); 1437 1438 vp = bp->b_vp; 1439 if (vp) 1440 vp_md = vp->v_vflag & VV_MD; 1441 else 1442 vp_md = 0; 1443 1444 /* 1445 * Mark the buffer clean. Increment the bufobj write count 1446 * before bundirty() call, to prevent other thread from seeing 1447 * empty dirty list and zero counter for writes in progress, 1448 * falsely indicating that the bufobj is clean. 1449 */ 1450 bufobj_wref(bp->b_bufobj); 1451 bundirty(bp); 1452 1453 bp->b_flags &= ~B_DONE; 1454 bp->b_ioflags &= ~BIO_ERROR; 1455 bp->b_flags |= B_CACHE; 1456 bp->b_iocmd = BIO_WRITE; 1457 1458 vfs_busy_pages(bp, 1); 1459 1460 /* 1461 * Normal bwrites pipeline writes 1462 */ 1463 bp->b_runningbufspace = bp->b_bufsize; 1464 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace); 1465 1466 if (!TD_IS_IDLETHREAD(curthread)) 1467 curthread->td_ru.ru_oublock++; 1468 if (oldflags & B_ASYNC) 1469 BUF_KERNPROC(bp); 1470 bp->b_iooffset = dbtob(bp->b_blkno); 1471 bstrategy(bp); 1472 1473 if ((oldflags & B_ASYNC) == 0) { 1474 int rtval = bufwait(bp); 1475 brelse(bp); 1476 return (rtval); 1477 } else if (space > hirunningspace) { 1478 /* 1479 * don't allow the async write to saturate the I/O 1480 * system. We will not deadlock here because 1481 * we are blocking waiting for I/O that is already in-progress 1482 * to complete. We do not block here if it is the update 1483 * or syncer daemon trying to clean up as that can lead 1484 * to deadlock. 1485 */ 1486 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 1487 waitrunningbufspace(); 1488 } 1489 1490 return (0); 1491 } 1492 1493 void 1494 bufbdflush(struct bufobj *bo, struct buf *bp) 1495 { 1496 struct buf *nbp; 1497 1498 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 1499 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 1500 altbufferflushes++; 1501 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 1502 BO_LOCK(bo); 1503 /* 1504 * Try to find a buffer to flush. 1505 */ 1506 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 1507 if ((nbp->b_vflags & BV_BKGRDINPROG) || 1508 BUF_LOCK(nbp, 1509 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 1510 continue; 1511 if (bp == nbp) 1512 panic("bdwrite: found ourselves"); 1513 BO_UNLOCK(bo); 1514 /* Don't countdeps with the bo lock held. */ 1515 if (buf_countdeps(nbp, 0)) { 1516 BO_LOCK(bo); 1517 BUF_UNLOCK(nbp); 1518 continue; 1519 } 1520 if (nbp->b_flags & B_CLUSTEROK) { 1521 vfs_bio_awrite(nbp); 1522 } else { 1523 bremfree(nbp); 1524 bawrite(nbp); 1525 } 1526 dirtybufferflushes++; 1527 break; 1528 } 1529 if (nbp == NULL) 1530 BO_UNLOCK(bo); 1531 } 1532 } 1533 1534 /* 1535 * Delayed write. (Buffer is marked dirty). Do not bother writing 1536 * anything if the buffer is marked invalid. 1537 * 1538 * Note that since the buffer must be completely valid, we can safely 1539 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 1540 * biodone() in order to prevent getblk from writing the buffer 1541 * out synchronously. 1542 */ 1543 void 1544 bdwrite(struct buf *bp) 1545 { 1546 struct thread *td = curthread; 1547 struct vnode *vp; 1548 struct bufobj *bo; 1549 1550 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1551 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1552 KASSERT((bp->b_flags & B_BARRIER) == 0, 1553 ("Barrier request in delayed write %p", bp)); 1554 BUF_ASSERT_HELD(bp); 1555 1556 if (bp->b_flags & B_INVAL) { 1557 brelse(bp); 1558 return; 1559 } 1560 1561 /* 1562 * If we have too many dirty buffers, don't create any more. 1563 * If we are wildly over our limit, then force a complete 1564 * cleanup. Otherwise, just keep the situation from getting 1565 * out of control. Note that we have to avoid a recursive 1566 * disaster and not try to clean up after our own cleanup! 1567 */ 1568 vp = bp->b_vp; 1569 bo = bp->b_bufobj; 1570 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 1571 td->td_pflags |= TDP_INBDFLUSH; 1572 BO_BDFLUSH(bo, bp); 1573 td->td_pflags &= ~TDP_INBDFLUSH; 1574 } else 1575 recursiveflushes++; 1576 1577 bdirty(bp); 1578 /* 1579 * Set B_CACHE, indicating that the buffer is fully valid. This is 1580 * true even of NFS now. 1581 */ 1582 bp->b_flags |= B_CACHE; 1583 1584 /* 1585 * This bmap keeps the system from needing to do the bmap later, 1586 * perhaps when the system is attempting to do a sync. Since it 1587 * is likely that the indirect block -- or whatever other datastructure 1588 * that the filesystem needs is still in memory now, it is a good 1589 * thing to do this. Note also, that if the pageout daemon is 1590 * requesting a sync -- there might not be enough memory to do 1591 * the bmap then... So, this is important to do. 1592 */ 1593 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 1594 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 1595 } 1596 1597 /* 1598 * Set the *dirty* buffer range based upon the VM system dirty 1599 * pages. 1600 * 1601 * Mark the buffer pages as clean. We need to do this here to 1602 * satisfy the vnode_pager and the pageout daemon, so that it 1603 * thinks that the pages have been "cleaned". Note that since 1604 * the pages are in a delayed write buffer -- the VFS layer 1605 * "will" see that the pages get written out on the next sync, 1606 * or perhaps the cluster will be completed. 1607 */ 1608 vfs_clean_pages_dirty_buf(bp); 1609 bqrelse(bp); 1610 1611 /* 1612 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 1613 * due to the softdep code. 1614 */ 1615 } 1616 1617 /* 1618 * bdirty: 1619 * 1620 * Turn buffer into delayed write request. We must clear BIO_READ and 1621 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 1622 * itself to properly update it in the dirty/clean lists. We mark it 1623 * B_DONE to ensure that any asynchronization of the buffer properly 1624 * clears B_DONE ( else a panic will occur later ). 1625 * 1626 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 1627 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 1628 * should only be called if the buffer is known-good. 1629 * 1630 * Since the buffer is not on a queue, we do not update the numfreebuffers 1631 * count. 1632 * 1633 * The buffer must be on QUEUE_NONE. 1634 */ 1635 void 1636 bdirty(struct buf *bp) 1637 { 1638 1639 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 1640 bp, bp->b_vp, bp->b_flags); 1641 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1642 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1643 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1644 BUF_ASSERT_HELD(bp); 1645 bp->b_flags &= ~(B_RELBUF); 1646 bp->b_iocmd = BIO_WRITE; 1647 1648 if ((bp->b_flags & B_DELWRI) == 0) { 1649 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 1650 reassignbuf(bp); 1651 bdirtyadd(); 1652 } 1653 } 1654 1655 /* 1656 * bundirty: 1657 * 1658 * Clear B_DELWRI for buffer. 1659 * 1660 * Since the buffer is not on a queue, we do not update the numfreebuffers 1661 * count. 1662 * 1663 * The buffer must be on QUEUE_NONE. 1664 */ 1665 1666 void 1667 bundirty(struct buf *bp) 1668 { 1669 1670 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1671 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1672 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1673 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1674 BUF_ASSERT_HELD(bp); 1675 1676 if (bp->b_flags & B_DELWRI) { 1677 bp->b_flags &= ~B_DELWRI; 1678 reassignbuf(bp); 1679 bdirtysub(); 1680 } 1681 /* 1682 * Since it is now being written, we can clear its deferred write flag. 1683 */ 1684 bp->b_flags &= ~B_DEFERRED; 1685 } 1686 1687 /* 1688 * bawrite: 1689 * 1690 * Asynchronous write. Start output on a buffer, but do not wait for 1691 * it to complete. The buffer is released when the output completes. 1692 * 1693 * bwrite() ( or the VOP routine anyway ) is responsible for handling 1694 * B_INVAL buffers. Not us. 1695 */ 1696 void 1697 bawrite(struct buf *bp) 1698 { 1699 1700 bp->b_flags |= B_ASYNC; 1701 (void) bwrite(bp); 1702 } 1703 1704 /* 1705 * babarrierwrite: 1706 * 1707 * Asynchronous barrier write. Start output on a buffer, but do not 1708 * wait for it to complete. Place a write barrier after this write so 1709 * that this buffer and all buffers written before it are committed to 1710 * the disk before any buffers written after this write are committed 1711 * to the disk. The buffer is released when the output completes. 1712 */ 1713 void 1714 babarrierwrite(struct buf *bp) 1715 { 1716 1717 bp->b_flags |= B_ASYNC | B_BARRIER; 1718 (void) bwrite(bp); 1719 } 1720 1721 /* 1722 * bbarrierwrite: 1723 * 1724 * Synchronous barrier write. Start output on a buffer and wait for 1725 * it to complete. Place a write barrier after this write so that 1726 * this buffer and all buffers written before it are committed to 1727 * the disk before any buffers written after this write are committed 1728 * to the disk. The buffer is released when the output completes. 1729 */ 1730 int 1731 bbarrierwrite(struct buf *bp) 1732 { 1733 1734 bp->b_flags |= B_BARRIER; 1735 return (bwrite(bp)); 1736 } 1737 1738 /* 1739 * bwillwrite: 1740 * 1741 * Called prior to the locking of any vnodes when we are expecting to 1742 * write. We do not want to starve the buffer cache with too many 1743 * dirty buffers so we block here. By blocking prior to the locking 1744 * of any vnodes we attempt to avoid the situation where a locked vnode 1745 * prevents the various system daemons from flushing related buffers. 1746 */ 1747 void 1748 bwillwrite(void) 1749 { 1750 1751 if (numdirtybuffers >= hidirtybuffers) { 1752 mtx_lock(&bdirtylock); 1753 while (numdirtybuffers >= hidirtybuffers) { 1754 bdirtywait = 1; 1755 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4), 1756 "flswai", 0); 1757 } 1758 mtx_unlock(&bdirtylock); 1759 } 1760 } 1761 1762 /* 1763 * Return true if we have too many dirty buffers. 1764 */ 1765 int 1766 buf_dirty_count_severe(void) 1767 { 1768 1769 return(numdirtybuffers >= hidirtybuffers); 1770 } 1771 1772 /* 1773 * brelse: 1774 * 1775 * Release a busy buffer and, if requested, free its resources. The 1776 * buffer will be stashed in the appropriate bufqueue[] allowing it 1777 * to be accessed later as a cache entity or reused for other purposes. 1778 */ 1779 void 1780 brelse(struct buf *bp) 1781 { 1782 int qindex; 1783 1784 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 1785 bp, bp->b_vp, bp->b_flags); 1786 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1787 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1788 KASSERT((bp->b_flags & B_VMIO) != 0 || (bp->b_flags & B_NOREUSE) == 0, 1789 ("brelse: non-VMIO buffer marked NOREUSE")); 1790 1791 if (BUF_LOCKRECURSED(bp)) { 1792 /* 1793 * Do not process, in particular, do not handle the 1794 * B_INVAL/B_RELBUF and do not release to free list. 1795 */ 1796 BUF_UNLOCK(bp); 1797 return; 1798 } 1799 1800 if (bp->b_flags & B_MANAGED) { 1801 bqrelse(bp); 1802 return; 1803 } 1804 1805 if ((bp->b_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) { 1806 BO_LOCK(bp->b_bufobj); 1807 bp->b_vflags &= ~BV_BKGRDERR; 1808 BO_UNLOCK(bp->b_bufobj); 1809 bdirty(bp); 1810 } 1811 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 1812 bp->b_error == EIO && !(bp->b_flags & B_INVAL)) { 1813 /* 1814 * Failed write, redirty. Must clear BIO_ERROR to prevent 1815 * pages from being scrapped. If the error is anything 1816 * other than an I/O error (EIO), assume that retrying 1817 * is futile. 1818 */ 1819 bp->b_ioflags &= ~BIO_ERROR; 1820 bdirty(bp); 1821 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 1822 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 1823 /* 1824 * Either a failed I/O or we were asked to free or not 1825 * cache the buffer. 1826 */ 1827 bp->b_flags |= B_INVAL; 1828 if (!LIST_EMPTY(&bp->b_dep)) 1829 buf_deallocate(bp); 1830 if (bp->b_flags & B_DELWRI) 1831 bdirtysub(); 1832 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1833 if ((bp->b_flags & B_VMIO) == 0) { 1834 allocbuf(bp, 0); 1835 if (bp->b_vp) 1836 brelvp(bp); 1837 } 1838 } 1839 1840 /* 1841 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_truncate() 1842 * is called with B_DELWRI set, the underlying pages may wind up 1843 * getting freed causing a previous write (bdwrite()) to get 'lost' 1844 * because pages associated with a B_DELWRI bp are marked clean. 1845 * 1846 * We still allow the B_INVAL case to call vfs_vmio_truncate(), even 1847 * if B_DELWRI is set. 1848 */ 1849 if (bp->b_flags & B_DELWRI) 1850 bp->b_flags &= ~B_RELBUF; 1851 1852 /* 1853 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1854 * constituted, not even NFS buffers now. Two flags effect this. If 1855 * B_INVAL, the struct buf is invalidated but the VM object is kept 1856 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1857 * 1858 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 1859 * invalidated. BIO_ERROR cannot be set for a failed write unless the 1860 * buffer is also B_INVAL because it hits the re-dirtying code above. 1861 * 1862 * Normally we can do this whether a buffer is B_DELWRI or not. If 1863 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1864 * the commit state and we cannot afford to lose the buffer. If the 1865 * buffer has a background write in progress, we need to keep it 1866 * around to prevent it from being reconstituted and starting a second 1867 * background write. 1868 */ 1869 if ((bp->b_flags & B_VMIO) && (bp->b_flags & B_NOCACHE || 1870 (bp->b_ioflags & BIO_ERROR && bp->b_iocmd == BIO_READ)) && 1871 !(bp->b_vp->v_mount != NULL && 1872 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 1873 !vn_isdisk(bp->b_vp, NULL) && (bp->b_flags & B_DELWRI))) { 1874 vfs_vmio_invalidate(bp); 1875 allocbuf(bp, 0); 1876 } 1877 1878 if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0 || 1879 (bp->b_flags & (B_DELWRI | B_NOREUSE)) == B_NOREUSE) { 1880 allocbuf(bp, 0); 1881 bp->b_flags &= ~B_NOREUSE; 1882 if (bp->b_vp != NULL) 1883 brelvp(bp); 1884 } 1885 1886 /* 1887 * If the buffer has junk contents signal it and eventually 1888 * clean up B_DELWRI and diassociate the vnode so that gbincore() 1889 * doesn't find it. 1890 */ 1891 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 1892 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 1893 bp->b_flags |= B_INVAL; 1894 if (bp->b_flags & B_INVAL) { 1895 if (bp->b_flags & B_DELWRI) 1896 bundirty(bp); 1897 if (bp->b_vp) 1898 brelvp(bp); 1899 } 1900 1901 /* buffers with no memory */ 1902 if (bp->b_bufsize == 0) { 1903 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1904 if (bp->b_vflags & BV_BKGRDINPROG) 1905 panic("losing buffer 1"); 1906 bufkvafree(bp); 1907 qindex = QUEUE_EMPTY; 1908 bp->b_flags |= B_AGE; 1909 /* buffers with junk contents */ 1910 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 1911 (bp->b_ioflags & BIO_ERROR)) { 1912 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1913 if (bp->b_vflags & BV_BKGRDINPROG) 1914 panic("losing buffer 2"); 1915 qindex = QUEUE_CLEAN; 1916 bp->b_flags |= B_AGE; 1917 /* remaining buffers */ 1918 } else if (bp->b_flags & B_DELWRI) 1919 qindex = QUEUE_DIRTY; 1920 else 1921 qindex = QUEUE_CLEAN; 1922 1923 binsfree(bp, qindex); 1924 1925 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 1926 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1927 panic("brelse: not dirty"); 1928 /* unlock */ 1929 BUF_UNLOCK(bp); 1930 } 1931 1932 /* 1933 * Release a buffer back to the appropriate queue but do not try to free 1934 * it. The buffer is expected to be used again soon. 1935 * 1936 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1937 * biodone() to requeue an async I/O on completion. It is also used when 1938 * known good buffers need to be requeued but we think we may need the data 1939 * again soon. 1940 * 1941 * XXX we should be able to leave the B_RELBUF hint set on completion. 1942 */ 1943 void 1944 bqrelse(struct buf *bp) 1945 { 1946 int qindex; 1947 1948 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1949 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1950 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1951 1952 if (BUF_LOCKRECURSED(bp)) { 1953 /* do not release to free list */ 1954 BUF_UNLOCK(bp); 1955 return; 1956 } 1957 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1958 1959 if (bp->b_flags & B_MANAGED) { 1960 if (bp->b_flags & B_REMFREE) 1961 bremfreef(bp); 1962 goto out; 1963 } 1964 1965 /* buffers with stale but valid contents */ 1966 if ((bp->b_flags & B_DELWRI) != 0 || (bp->b_vflags & (BV_BKGRDINPROG | 1967 BV_BKGRDERR)) == BV_BKGRDERR) { 1968 BO_LOCK(bp->b_bufobj); 1969 bp->b_vflags &= ~BV_BKGRDERR; 1970 BO_UNLOCK(bp->b_bufobj); 1971 qindex = QUEUE_DIRTY; 1972 } else { 1973 if ((bp->b_flags & B_DELWRI) == 0 && 1974 (bp->b_xflags & BX_VNDIRTY)) 1975 panic("bqrelse: not dirty"); 1976 if ((bp->b_flags & B_NOREUSE) != 0) { 1977 brelse(bp); 1978 return; 1979 } 1980 qindex = QUEUE_CLEAN; 1981 } 1982 binsfree(bp, qindex); 1983 1984 out: 1985 /* unlock */ 1986 BUF_UNLOCK(bp); 1987 } 1988 1989 /* 1990 * Complete I/O to a VMIO backed page. Validate the pages as appropriate, 1991 * restore bogus pages. 1992 */ 1993 static void 1994 vfs_vmio_iodone(struct buf *bp) 1995 { 1996 vm_ooffset_t foff; 1997 vm_page_t m; 1998 vm_object_t obj; 1999 struct vnode *vp; 2000 int bogus, i, iosize; 2001 2002 obj = bp->b_bufobj->bo_object; 2003 KASSERT(obj->paging_in_progress >= bp->b_npages, 2004 ("vfs_vmio_iodone: paging in progress(%d) < b_npages(%d)", 2005 obj->paging_in_progress, bp->b_npages)); 2006 2007 vp = bp->b_vp; 2008 KASSERT(vp->v_holdcnt > 0, 2009 ("vfs_vmio_iodone: vnode %p has zero hold count", vp)); 2010 KASSERT(vp->v_object != NULL, 2011 ("vfs_vmio_iodone: vnode %p has no vm_object", vp)); 2012 2013 foff = bp->b_offset; 2014 KASSERT(bp->b_offset != NOOFFSET, 2015 ("vfs_vmio_iodone: bp %p has no buffer offset", bp)); 2016 2017 bogus = 0; 2018 iosize = bp->b_bcount - bp->b_resid; 2019 VM_OBJECT_WLOCK(obj); 2020 for (i = 0; i < bp->b_npages; i++) { 2021 int resid; 2022 2023 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 2024 if (resid > iosize) 2025 resid = iosize; 2026 2027 /* 2028 * cleanup bogus pages, restoring the originals 2029 */ 2030 m = bp->b_pages[i]; 2031 if (m == bogus_page) { 2032 bogus = 1; 2033 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 2034 if (m == NULL) 2035 panic("biodone: page disappeared!"); 2036 bp->b_pages[i] = m; 2037 } else if ((bp->b_iocmd == BIO_READ) && resid > 0) { 2038 /* 2039 * In the write case, the valid and clean bits are 2040 * already changed correctly ( see bdwrite() ), so we 2041 * only need to do this here in the read case. 2042 */ 2043 KASSERT((m->dirty & vm_page_bits(foff & PAGE_MASK, 2044 resid)) == 0, ("vfs_vmio_iodone: page %p " 2045 "has unexpected dirty bits", m)); 2046 vfs_page_set_valid(bp, foff, m); 2047 } 2048 KASSERT(OFF_TO_IDX(foff) == m->pindex, 2049 ("vfs_vmio_iodone: foff(%jd)/pindex(%ju) mismatch", 2050 (intmax_t)foff, (uintmax_t)m->pindex)); 2051 2052 vm_page_sunbusy(m); 2053 vm_object_pip_subtract(obj, 1); 2054 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2055 iosize -= resid; 2056 } 2057 vm_object_pip_wakeupn(obj, 0); 2058 VM_OBJECT_WUNLOCK(obj); 2059 if (bogus && buf_mapped(bp)) { 2060 BUF_CHECK_MAPPED(bp); 2061 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 2062 bp->b_pages, bp->b_npages); 2063 } 2064 } 2065 2066 /* 2067 * Unwire a page held by a buf and place it on the appropriate vm queue. 2068 */ 2069 static void 2070 vfs_vmio_unwire(struct buf *bp, vm_page_t m) 2071 { 2072 bool freed; 2073 2074 vm_page_lock(m); 2075 if (vm_page_unwire(m, PQ_NONE)) { 2076 /* 2077 * Determine if the page should be freed before adding 2078 * it to the inactive queue. 2079 */ 2080 if (m->valid == 0) { 2081 freed = !vm_page_busied(m); 2082 if (freed) 2083 vm_page_free(m); 2084 } else if ((bp->b_flags & B_DIRECT) != 0) 2085 freed = vm_page_try_to_free(m); 2086 else 2087 freed = false; 2088 if (!freed) { 2089 /* 2090 * If the page is unlikely to be reused, let the 2091 * VM know. Otherwise, maintain LRU page 2092 * ordering and put the page at the tail of the 2093 * inactive queue. 2094 */ 2095 if ((bp->b_flags & B_NOREUSE) != 0) 2096 vm_page_deactivate_noreuse(m); 2097 else 2098 vm_page_deactivate(m); 2099 } 2100 } 2101 vm_page_unlock(m); 2102 } 2103 2104 /* 2105 * Perform page invalidation when a buffer is released. The fully invalid 2106 * pages will be reclaimed later in vfs_vmio_truncate(). 2107 */ 2108 static void 2109 vfs_vmio_invalidate(struct buf *bp) 2110 { 2111 vm_object_t obj; 2112 vm_page_t m; 2113 int i, resid, poffset, presid; 2114 2115 if (buf_mapped(bp)) { 2116 BUF_CHECK_MAPPED(bp); 2117 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages); 2118 } else 2119 BUF_CHECK_UNMAPPED(bp); 2120 /* 2121 * Get the base offset and length of the buffer. Note that 2122 * in the VMIO case if the buffer block size is not 2123 * page-aligned then b_data pointer may not be page-aligned. 2124 * But our b_pages[] array *IS* page aligned. 2125 * 2126 * block sizes less then DEV_BSIZE (usually 512) are not 2127 * supported due to the page granularity bits (m->valid, 2128 * m->dirty, etc...). 2129 * 2130 * See man buf(9) for more information 2131 */ 2132 obj = bp->b_bufobj->bo_object; 2133 resid = bp->b_bufsize; 2134 poffset = bp->b_offset & PAGE_MASK; 2135 VM_OBJECT_WLOCK(obj); 2136 for (i = 0; i < bp->b_npages; i++) { 2137 m = bp->b_pages[i]; 2138 if (m == bogus_page) 2139 panic("vfs_vmio_invalidate: Unexpected bogus page."); 2140 bp->b_pages[i] = NULL; 2141 2142 presid = resid > (PAGE_SIZE - poffset) ? 2143 (PAGE_SIZE - poffset) : resid; 2144 KASSERT(presid >= 0, ("brelse: extra page")); 2145 while (vm_page_xbusied(m)) { 2146 vm_page_lock(m); 2147 VM_OBJECT_WUNLOCK(obj); 2148 vm_page_busy_sleep(m, "mbncsh"); 2149 VM_OBJECT_WLOCK(obj); 2150 } 2151 if (pmap_page_wired_mappings(m) == 0) 2152 vm_page_set_invalid(m, poffset, presid); 2153 vfs_vmio_unwire(bp, m); 2154 resid -= presid; 2155 poffset = 0; 2156 } 2157 VM_OBJECT_WUNLOCK(obj); 2158 bp->b_npages = 0; 2159 } 2160 2161 /* 2162 * Page-granular truncation of an existing VMIO buffer. 2163 */ 2164 static void 2165 vfs_vmio_truncate(struct buf *bp, int desiredpages) 2166 { 2167 vm_object_t obj; 2168 vm_page_t m; 2169 int i; 2170 2171 if (bp->b_npages == desiredpages) 2172 return; 2173 2174 if (buf_mapped(bp)) { 2175 BUF_CHECK_MAPPED(bp); 2176 pmap_qremove((vm_offset_t)trunc_page((vm_offset_t)bp->b_data) + 2177 (desiredpages << PAGE_SHIFT), bp->b_npages - desiredpages); 2178 } else 2179 BUF_CHECK_UNMAPPED(bp); 2180 obj = bp->b_bufobj->bo_object; 2181 if (obj != NULL) 2182 VM_OBJECT_WLOCK(obj); 2183 for (i = desiredpages; i < bp->b_npages; i++) { 2184 m = bp->b_pages[i]; 2185 KASSERT(m != bogus_page, ("allocbuf: bogus page found")); 2186 bp->b_pages[i] = NULL; 2187 vfs_vmio_unwire(bp, m); 2188 } 2189 if (obj != NULL) 2190 VM_OBJECT_WUNLOCK(obj); 2191 bp->b_npages = desiredpages; 2192 } 2193 2194 /* 2195 * Byte granular extension of VMIO buffers. 2196 */ 2197 static void 2198 vfs_vmio_extend(struct buf *bp, int desiredpages, int size) 2199 { 2200 /* 2201 * We are growing the buffer, possibly in a 2202 * byte-granular fashion. 2203 */ 2204 vm_object_t obj; 2205 vm_offset_t toff; 2206 vm_offset_t tinc; 2207 vm_page_t m; 2208 2209 /* 2210 * Step 1, bring in the VM pages from the object, allocating 2211 * them if necessary. We must clear B_CACHE if these pages 2212 * are not valid for the range covered by the buffer. 2213 */ 2214 obj = bp->b_bufobj->bo_object; 2215 VM_OBJECT_WLOCK(obj); 2216 while (bp->b_npages < desiredpages) { 2217 /* 2218 * We must allocate system pages since blocking 2219 * here could interfere with paging I/O, no 2220 * matter which process we are. 2221 * 2222 * Only exclusive busy can be tested here. 2223 * Blocking on shared busy might lead to 2224 * deadlocks once allocbuf() is called after 2225 * pages are vfs_busy_pages(). 2226 */ 2227 m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) + bp->b_npages, 2228 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM | 2229 VM_ALLOC_WIRED | VM_ALLOC_IGN_SBUSY | 2230 VM_ALLOC_COUNT(desiredpages - bp->b_npages)); 2231 if (m->valid == 0) 2232 bp->b_flags &= ~B_CACHE; 2233 bp->b_pages[bp->b_npages] = m; 2234 ++bp->b_npages; 2235 } 2236 2237 /* 2238 * Step 2. We've loaded the pages into the buffer, 2239 * we have to figure out if we can still have B_CACHE 2240 * set. Note that B_CACHE is set according to the 2241 * byte-granular range ( bcount and size ), not the 2242 * aligned range ( newbsize ). 2243 * 2244 * The VM test is against m->valid, which is DEV_BSIZE 2245 * aligned. Needless to say, the validity of the data 2246 * needs to also be DEV_BSIZE aligned. Note that this 2247 * fails with NFS if the server or some other client 2248 * extends the file's EOF. If our buffer is resized, 2249 * B_CACHE may remain set! XXX 2250 */ 2251 toff = bp->b_bcount; 2252 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 2253 while ((bp->b_flags & B_CACHE) && toff < size) { 2254 vm_pindex_t pi; 2255 2256 if (tinc > (size - toff)) 2257 tinc = size - toff; 2258 pi = ((bp->b_offset & PAGE_MASK) + toff) >> PAGE_SHIFT; 2259 m = bp->b_pages[pi]; 2260 vfs_buf_test_cache(bp, bp->b_offset, toff, tinc, m); 2261 toff += tinc; 2262 tinc = PAGE_SIZE; 2263 } 2264 VM_OBJECT_WUNLOCK(obj); 2265 2266 /* 2267 * Step 3, fixup the KVA pmap. 2268 */ 2269 if (buf_mapped(bp)) 2270 bpmap_qenter(bp); 2271 else 2272 BUF_CHECK_UNMAPPED(bp); 2273 } 2274 2275 /* 2276 * Check to see if a block at a particular lbn is available for a clustered 2277 * write. 2278 */ 2279 static int 2280 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 2281 { 2282 struct buf *bpa; 2283 int match; 2284 2285 match = 0; 2286 2287 /* If the buf isn't in core skip it */ 2288 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 2289 return (0); 2290 2291 /* If the buf is busy we don't want to wait for it */ 2292 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2293 return (0); 2294 2295 /* Only cluster with valid clusterable delayed write buffers */ 2296 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 2297 (B_DELWRI | B_CLUSTEROK)) 2298 goto done; 2299 2300 if (bpa->b_bufsize != size) 2301 goto done; 2302 2303 /* 2304 * Check to see if it is in the expected place on disk and that the 2305 * block has been mapped. 2306 */ 2307 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 2308 match = 1; 2309 done: 2310 BUF_UNLOCK(bpa); 2311 return (match); 2312 } 2313 2314 /* 2315 * vfs_bio_awrite: 2316 * 2317 * Implement clustered async writes for clearing out B_DELWRI buffers. 2318 * This is much better then the old way of writing only one buffer at 2319 * a time. Note that we may not be presented with the buffers in the 2320 * correct order, so we search for the cluster in both directions. 2321 */ 2322 int 2323 vfs_bio_awrite(struct buf *bp) 2324 { 2325 struct bufobj *bo; 2326 int i; 2327 int j; 2328 daddr_t lblkno = bp->b_lblkno; 2329 struct vnode *vp = bp->b_vp; 2330 int ncl; 2331 int nwritten; 2332 int size; 2333 int maxcl; 2334 int gbflags; 2335 2336 bo = &vp->v_bufobj; 2337 gbflags = (bp->b_data == unmapped_buf) ? GB_UNMAPPED : 0; 2338 /* 2339 * right now we support clustered writing only to regular files. If 2340 * we find a clusterable block we could be in the middle of a cluster 2341 * rather then at the beginning. 2342 */ 2343 if ((vp->v_type == VREG) && 2344 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 2345 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 2346 2347 size = vp->v_mount->mnt_stat.f_iosize; 2348 maxcl = MAXPHYS / size; 2349 2350 BO_RLOCK(bo); 2351 for (i = 1; i < maxcl; i++) 2352 if (vfs_bio_clcheck(vp, size, lblkno + i, 2353 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 2354 break; 2355 2356 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 2357 if (vfs_bio_clcheck(vp, size, lblkno - j, 2358 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 2359 break; 2360 BO_RUNLOCK(bo); 2361 --j; 2362 ncl = i + j; 2363 /* 2364 * this is a possible cluster write 2365 */ 2366 if (ncl != 1) { 2367 BUF_UNLOCK(bp); 2368 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl, 2369 gbflags); 2370 return (nwritten); 2371 } 2372 } 2373 bremfree(bp); 2374 bp->b_flags |= B_ASYNC; 2375 /* 2376 * default (old) behavior, writing out only one block 2377 * 2378 * XXX returns b_bufsize instead of b_bcount for nwritten? 2379 */ 2380 nwritten = bp->b_bufsize; 2381 (void) bwrite(bp); 2382 2383 return (nwritten); 2384 } 2385 2386 /* 2387 * Ask the bufdaemon for help, or act as bufdaemon itself, when a 2388 * locked vnode is supplied. 2389 */ 2390 static void 2391 getnewbuf_bufd_help(struct vnode *vp, int gbflags, int slpflag, int slptimeo, 2392 int defrag) 2393 { 2394 struct thread *td; 2395 char *waitmsg; 2396 int error, fl, flags, norunbuf; 2397 2398 mtx_assert(&bqclean, MA_OWNED); 2399 2400 if (defrag) { 2401 flags = VFS_BIO_NEED_BUFSPACE; 2402 waitmsg = "nbufkv"; 2403 } else if (bufspace >= hibufspace) { 2404 waitmsg = "nbufbs"; 2405 flags = VFS_BIO_NEED_BUFSPACE; 2406 } else { 2407 waitmsg = "newbuf"; 2408 flags = VFS_BIO_NEED_ANY; 2409 } 2410 atomic_set_int(&needsbuffer, flags); 2411 mtx_unlock(&bqclean); 2412 2413 bd_speedup(); /* heeeelp */ 2414 if ((gbflags & GB_NOWAIT_BD) != 0) 2415 return; 2416 2417 td = curthread; 2418 rw_wlock(&nblock); 2419 while ((needsbuffer & flags) != 0) { 2420 if (vp != NULL && vp->v_type != VCHR && 2421 (td->td_pflags & TDP_BUFNEED) == 0) { 2422 rw_wunlock(&nblock); 2423 /* 2424 * getblk() is called with a vnode locked, and 2425 * some majority of the dirty buffers may as 2426 * well belong to the vnode. Flushing the 2427 * buffers there would make a progress that 2428 * cannot be achieved by the buf_daemon, that 2429 * cannot lock the vnode. 2430 */ 2431 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) | 2432 (td->td_pflags & TDP_NORUNNINGBUF); 2433 2434 /* 2435 * Play bufdaemon. The getnewbuf() function 2436 * may be called while the thread owns lock 2437 * for another dirty buffer for the same 2438 * vnode, which makes it impossible to use 2439 * VOP_FSYNC() there, due to the buffer lock 2440 * recursion. 2441 */ 2442 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF; 2443 fl = buf_flush(vp, flushbufqtarget); 2444 td->td_pflags &= norunbuf; 2445 rw_wlock(&nblock); 2446 if (fl != 0) 2447 continue; 2448 if ((needsbuffer & flags) == 0) 2449 break; 2450 } 2451 error = rw_sleep(__DEVOLATILE(void *, &needsbuffer), &nblock, 2452 (PRIBIO + 4) | slpflag, waitmsg, slptimeo); 2453 if (error != 0) 2454 break; 2455 } 2456 rw_wunlock(&nblock); 2457 } 2458 2459 static void 2460 getnewbuf_reuse_bp(struct buf *bp, int qindex) 2461 { 2462 2463 CTR6(KTR_BUF, "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d " 2464 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags, 2465 bp->b_kvasize, bp->b_bufsize, qindex); 2466 mtx_assert(&bqclean, MA_NOTOWNED); 2467 2468 /* 2469 * Note: we no longer distinguish between VMIO and non-VMIO 2470 * buffers. 2471 */ 2472 KASSERT((bp->b_flags & (B_DELWRI | B_NOREUSE)) == 0, 2473 ("invalid buffer %p flags %#x found in queue %d", bp, bp->b_flags, 2474 qindex)); 2475 2476 /* 2477 * When recycling a clean buffer we have to truncate it and 2478 * release the vnode. 2479 */ 2480 if (qindex == QUEUE_CLEAN) { 2481 allocbuf(bp, 0); 2482 if (bp->b_vp != NULL) 2483 brelvp(bp); 2484 } 2485 2486 /* 2487 * Get the rest of the buffer freed up. b_kva* is still valid 2488 * after this operation. 2489 */ 2490 if (bp->b_rcred != NOCRED) { 2491 crfree(bp->b_rcred); 2492 bp->b_rcred = NOCRED; 2493 } 2494 if (bp->b_wcred != NOCRED) { 2495 crfree(bp->b_wcred); 2496 bp->b_wcred = NOCRED; 2497 } 2498 if (!LIST_EMPTY(&bp->b_dep)) 2499 buf_deallocate(bp); 2500 if (bp->b_vflags & BV_BKGRDINPROG) 2501 panic("losing buffer 3"); 2502 KASSERT(bp->b_vp == NULL, ("bp: %p still has vnode %p. qindex: %d", 2503 bp, bp->b_vp, qindex)); 2504 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 2505 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags)); 2506 KASSERT(bp->b_npages == 0, 2507 ("bp: %p still has %d vm pages\n", bp, bp->b_npages)); 2508 2509 bp->b_flags = 0; 2510 bp->b_ioflags = 0; 2511 bp->b_xflags = 0; 2512 KASSERT((bp->b_flags & B_INFREECNT) == 0, 2513 ("buf %p still counted as free?", bp)); 2514 bp->b_vflags = 0; 2515 bp->b_vp = NULL; 2516 bp->b_blkno = bp->b_lblkno = 0; 2517 bp->b_offset = NOOFFSET; 2518 bp->b_iodone = 0; 2519 bp->b_error = 0; 2520 bp->b_resid = 0; 2521 bp->b_bcount = 0; 2522 bp->b_npages = 0; 2523 bp->b_dirtyoff = bp->b_dirtyend = 0; 2524 bp->b_bufobj = NULL; 2525 bp->b_pin_count = 0; 2526 bp->b_data = bp->b_kvabase; 2527 bp->b_fsprivate1 = NULL; 2528 bp->b_fsprivate2 = NULL; 2529 bp->b_fsprivate3 = NULL; 2530 2531 LIST_INIT(&bp->b_dep); 2532 } 2533 2534 static struct buf * 2535 getnewbuf_scan(int maxsize, int defrag, int unmapped, int metadata) 2536 { 2537 struct buf *bp, *nbp; 2538 int nqindex, qindex, pass; 2539 2540 KASSERT(!unmapped || !defrag, ("both unmapped and defrag")); 2541 2542 pass = 0; 2543 restart: 2544 if (pass != 0) 2545 atomic_add_int(&getnewbufrestarts, 1); 2546 2547 nbp = NULL; 2548 mtx_lock(&bqclean); 2549 /* 2550 * If we're not defragging or low on bufspace attempt to make a new 2551 * buf from a header. 2552 */ 2553 if (defrag == 0 && bufspace + maxsize < hibufspace) { 2554 nqindex = QUEUE_EMPTY; 2555 nbp = TAILQ_FIRST(&bufqueues[nqindex]); 2556 } 2557 /* 2558 * All available buffers might be clean or we need to start recycling. 2559 */ 2560 if (nbp == NULL) { 2561 nqindex = QUEUE_CLEAN; 2562 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2563 } 2564 2565 /* 2566 * Run scan, possibly freeing data and/or kva mappings on the fly 2567 * depending. 2568 */ 2569 while ((bp = nbp) != NULL) { 2570 qindex = nqindex; 2571 2572 /* 2573 * Calculate next bp (we can only use it if we do not 2574 * release the bqlock) 2575 */ 2576 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 2577 switch (qindex) { 2578 case QUEUE_EMPTY: 2579 nqindex = QUEUE_CLEAN; 2580 nbp = TAILQ_FIRST(&bufqueues[nqindex]); 2581 if (nbp != NULL) 2582 break; 2583 /* FALLTHROUGH */ 2584 case QUEUE_CLEAN: 2585 if (metadata && pass == 0) { 2586 pass = 1; 2587 nqindex = QUEUE_EMPTY; 2588 nbp = TAILQ_FIRST(&bufqueues[nqindex]); 2589 } 2590 /* 2591 * nbp is NULL. 2592 */ 2593 break; 2594 } 2595 } 2596 /* 2597 * If we are defragging then we need a buffer with 2598 * b_kvasize != 0. This situation occurs when we 2599 * have many unmapped bufs. 2600 */ 2601 if (defrag && bp->b_kvasize == 0) 2602 continue; 2603 2604 /* 2605 * Start freeing the bp. This is somewhat involved. nbp 2606 * remains valid only for QUEUE_EMPTY[KVA] bp's. 2607 */ 2608 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2609 continue; 2610 /* 2611 * BKGRDINPROG can only be set with the buf and bufobj 2612 * locks both held. We tolerate a race to clear it here. 2613 */ 2614 if (bp->b_vflags & BV_BKGRDINPROG) { 2615 BUF_UNLOCK(bp); 2616 continue; 2617 } 2618 2619 /* 2620 * Requeue the background write buffer with error. 2621 */ 2622 if ((bp->b_vflags & BV_BKGRDERR) != 0) { 2623 bremfreel(bp); 2624 mtx_unlock(&bqclean); 2625 bqrelse(bp); 2626 continue; 2627 } 2628 2629 KASSERT(bp->b_qindex == qindex, 2630 ("getnewbuf: inconsistent queue %d bp %p", qindex, bp)); 2631 2632 bremfreel(bp); 2633 mtx_unlock(&bqclean); 2634 2635 /* 2636 * NOTE: nbp is now entirely invalid. We can only restart 2637 * the scan from this point on. 2638 */ 2639 getnewbuf_reuse_bp(bp, qindex); 2640 mtx_assert(&bqclean, MA_NOTOWNED); 2641 2642 /* 2643 * If we are defragging then free the buffer. 2644 */ 2645 if (defrag) { 2646 bp->b_flags |= B_INVAL; 2647 brelse(bp); 2648 defrag = 0; 2649 goto restart; 2650 } 2651 2652 /* 2653 * Notify any waiters for the buffer lock about 2654 * identity change by freeing the buffer. 2655 */ 2656 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp)) { 2657 bp->b_flags |= B_INVAL; 2658 brelse(bp); 2659 goto restart; 2660 } 2661 2662 if (metadata) 2663 break; 2664 2665 /* 2666 * If we are overcomitted then recover the buffer and its 2667 * KVM space. This occurs in rare situations when multiple 2668 * processes are blocked in getnewbuf() or allocbuf(). 2669 */ 2670 if (bufspace >= hibufspace && bp->b_kvasize != 0) { 2671 bp->b_flags |= B_INVAL; 2672 brelse(bp); 2673 goto restart; 2674 } 2675 break; 2676 } 2677 return (bp); 2678 } 2679 2680 /* 2681 * getnewbuf: 2682 * 2683 * Find and initialize a new buffer header, freeing up existing buffers 2684 * in the bufqueues as necessary. The new buffer is returned locked. 2685 * 2686 * Important: B_INVAL is not set. If the caller wishes to throw the 2687 * buffer away, the caller must set B_INVAL prior to calling brelse(). 2688 * 2689 * We block if: 2690 * We have insufficient buffer headers 2691 * We have insufficient buffer space 2692 * buffer_arena is too fragmented ( space reservation fails ) 2693 * If we have to flush dirty buffers ( but we try to avoid this ) 2694 */ 2695 static struct buf * 2696 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int size, int maxsize, 2697 int gbflags) 2698 { 2699 struct buf *bp; 2700 int defrag, metadata; 2701 2702 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 2703 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 2704 if (!unmapped_buf_allowed) 2705 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC); 2706 2707 defrag = 0; 2708 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 || 2709 vp->v_type == VCHR) 2710 metadata = 1; 2711 else 2712 metadata = 0; 2713 /* 2714 * We can't afford to block since we might be holding a vnode lock, 2715 * which may prevent system daemons from running. We deal with 2716 * low-memory situations by proactively returning memory and running 2717 * async I/O rather then sync I/O. 2718 */ 2719 atomic_add_int(&getnewbufcalls, 1); 2720 restart: 2721 bp = getnewbuf_scan(maxsize, defrag, (gbflags & (GB_UNMAPPED | 2722 GB_KVAALLOC)) == GB_UNMAPPED, metadata); 2723 if (bp != NULL) 2724 defrag = 0; 2725 2726 /* 2727 * If we exhausted our list, sleep as appropriate. We may have to 2728 * wakeup various daemons and write out some dirty buffers. 2729 * 2730 * Generally we are sleeping due to insufficient buffer space. 2731 */ 2732 if (bp == NULL) { 2733 mtx_assert(&bqclean, MA_OWNED); 2734 getnewbuf_bufd_help(vp, gbflags, slpflag, slptimeo, defrag); 2735 mtx_assert(&bqclean, MA_NOTOWNED); 2736 } else if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == GB_UNMAPPED) { 2737 mtx_assert(&bqclean, MA_NOTOWNED); 2738 2739 bufkvafree(bp); 2740 atomic_add_int(&bufreusecnt, 1); 2741 } else { 2742 mtx_assert(&bqclean, MA_NOTOWNED); 2743 2744 /* 2745 * We finally have a valid bp. We aren't quite out of the 2746 * woods, we still have to reserve kva space. In order to 2747 * keep fragmentation sane we only allocate kva in BKVASIZE 2748 * chunks. 2749 */ 2750 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2751 2752 if (maxsize != bp->b_kvasize && 2753 bufkvaalloc(bp, maxsize, gbflags)) { 2754 defrag = 1; 2755 bp->b_flags |= B_INVAL; 2756 brelse(bp); 2757 goto restart; 2758 } else if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == 2759 (GB_UNMAPPED | GB_KVAALLOC)) { 2760 bp->b_data = unmapped_buf; 2761 BUF_CHECK_UNMAPPED(bp); 2762 } 2763 atomic_add_int(&bufreusecnt, 1); 2764 } 2765 return (bp); 2766 } 2767 2768 /* 2769 * buf_daemon: 2770 * 2771 * buffer flushing daemon. Buffers are normally flushed by the 2772 * update daemon but if it cannot keep up this process starts to 2773 * take the load in an attempt to prevent getnewbuf() from blocking. 2774 */ 2775 2776 static struct kproc_desc buf_kp = { 2777 "bufdaemon", 2778 buf_daemon, 2779 &bufdaemonproc 2780 }; 2781 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 2782 2783 static int 2784 buf_flush(struct vnode *vp, int target) 2785 { 2786 int flushed; 2787 2788 flushed = flushbufqueues(vp, target, 0); 2789 if (flushed == 0) { 2790 /* 2791 * Could not find any buffers without rollback 2792 * dependencies, so just write the first one 2793 * in the hopes of eventually making progress. 2794 */ 2795 if (vp != NULL && target > 2) 2796 target /= 2; 2797 flushbufqueues(vp, target, 1); 2798 } 2799 return (flushed); 2800 } 2801 2802 static void 2803 buf_daemon() 2804 { 2805 int lodirty; 2806 2807 /* 2808 * This process needs to be suspended prior to shutdown sync. 2809 */ 2810 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2811 SHUTDOWN_PRI_LAST); 2812 2813 /* 2814 * This process is allowed to take the buffer cache to the limit 2815 */ 2816 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 2817 mtx_lock(&bdlock); 2818 for (;;) { 2819 bd_request = 0; 2820 mtx_unlock(&bdlock); 2821 2822 kproc_suspend_check(bufdaemonproc); 2823 lodirty = lodirtybuffers; 2824 if (bd_speedupreq) { 2825 lodirty = numdirtybuffers / 2; 2826 bd_speedupreq = 0; 2827 } 2828 /* 2829 * Do the flush. Limit the amount of in-transit I/O we 2830 * allow to build up, otherwise we would completely saturate 2831 * the I/O system. 2832 */ 2833 while (numdirtybuffers > lodirty) { 2834 if (buf_flush(NULL, numdirtybuffers - lodirty) == 0) 2835 break; 2836 kern_yield(PRI_USER); 2837 } 2838 2839 /* 2840 * Only clear bd_request if we have reached our low water 2841 * mark. The buf_daemon normally waits 1 second and 2842 * then incrementally flushes any dirty buffers that have 2843 * built up, within reason. 2844 * 2845 * If we were unable to hit our low water mark and couldn't 2846 * find any flushable buffers, we sleep for a short period 2847 * to avoid endless loops on unlockable buffers. 2848 */ 2849 mtx_lock(&bdlock); 2850 if (numdirtybuffers <= lodirtybuffers) { 2851 /* 2852 * We reached our low water mark, reset the 2853 * request and sleep until we are needed again. 2854 * The sleep is just so the suspend code works. 2855 */ 2856 bd_request = 0; 2857 /* 2858 * Do an extra wakeup in case dirty threshold 2859 * changed via sysctl and the explicit transition 2860 * out of shortfall was missed. 2861 */ 2862 bdirtywakeup(); 2863 if (runningbufspace <= lorunningspace) 2864 runningwakeup(); 2865 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 2866 } else { 2867 /* 2868 * We couldn't find any flushable dirty buffers but 2869 * still have too many dirty buffers, we 2870 * have to sleep and try again. (rare) 2871 */ 2872 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 2873 } 2874 } 2875 } 2876 2877 /* 2878 * flushbufqueues: 2879 * 2880 * Try to flush a buffer in the dirty queue. We must be careful to 2881 * free up B_INVAL buffers instead of write them, which NFS is 2882 * particularly sensitive to. 2883 */ 2884 static int flushwithdeps = 0; 2885 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 2886 0, "Number of buffers flushed with dependecies that require rollbacks"); 2887 2888 static int 2889 flushbufqueues(struct vnode *lvp, int target, int flushdeps) 2890 { 2891 struct buf *sentinel; 2892 struct vnode *vp; 2893 struct mount *mp; 2894 struct buf *bp; 2895 int hasdeps; 2896 int flushed; 2897 int queue; 2898 int error; 2899 bool unlock; 2900 2901 flushed = 0; 2902 queue = QUEUE_DIRTY; 2903 bp = NULL; 2904 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 2905 sentinel->b_qindex = QUEUE_SENTINEL; 2906 mtx_lock(&bqdirty); 2907 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist); 2908 mtx_unlock(&bqdirty); 2909 while (flushed != target) { 2910 maybe_yield(); 2911 mtx_lock(&bqdirty); 2912 bp = TAILQ_NEXT(sentinel, b_freelist); 2913 if (bp != NULL) { 2914 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2915 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel, 2916 b_freelist); 2917 } else { 2918 mtx_unlock(&bqdirty); 2919 break; 2920 } 2921 /* 2922 * Skip sentinels inserted by other invocations of the 2923 * flushbufqueues(), taking care to not reorder them. 2924 * 2925 * Only flush the buffers that belong to the 2926 * vnode locked by the curthread. 2927 */ 2928 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL && 2929 bp->b_vp != lvp)) { 2930 mtx_unlock(&bqdirty); 2931 continue; 2932 } 2933 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL); 2934 mtx_unlock(&bqdirty); 2935 if (error != 0) 2936 continue; 2937 if (bp->b_pin_count > 0) { 2938 BUF_UNLOCK(bp); 2939 continue; 2940 } 2941 /* 2942 * BKGRDINPROG can only be set with the buf and bufobj 2943 * locks both held. We tolerate a race to clear it here. 2944 */ 2945 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 2946 (bp->b_flags & B_DELWRI) == 0) { 2947 BUF_UNLOCK(bp); 2948 continue; 2949 } 2950 if (bp->b_flags & B_INVAL) { 2951 bremfreef(bp); 2952 brelse(bp); 2953 flushed++; 2954 continue; 2955 } 2956 2957 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 2958 if (flushdeps == 0) { 2959 BUF_UNLOCK(bp); 2960 continue; 2961 } 2962 hasdeps = 1; 2963 } else 2964 hasdeps = 0; 2965 /* 2966 * We must hold the lock on a vnode before writing 2967 * one of its buffers. Otherwise we may confuse, or 2968 * in the case of a snapshot vnode, deadlock the 2969 * system. 2970 * 2971 * The lock order here is the reverse of the normal 2972 * of vnode followed by buf lock. This is ok because 2973 * the NOWAIT will prevent deadlock. 2974 */ 2975 vp = bp->b_vp; 2976 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 2977 BUF_UNLOCK(bp); 2978 continue; 2979 } 2980 if (lvp == NULL) { 2981 unlock = true; 2982 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT); 2983 } else { 2984 ASSERT_VOP_LOCKED(vp, "getbuf"); 2985 unlock = false; 2986 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 : 2987 vn_lock(vp, LK_TRYUPGRADE); 2988 } 2989 if (error == 0) { 2990 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 2991 bp, bp->b_vp, bp->b_flags); 2992 if (curproc == bufdaemonproc) { 2993 vfs_bio_awrite(bp); 2994 } else { 2995 bremfree(bp); 2996 bwrite(bp); 2997 notbufdflushes++; 2998 } 2999 vn_finished_write(mp); 3000 if (unlock) 3001 VOP_UNLOCK(vp, 0); 3002 flushwithdeps += hasdeps; 3003 flushed++; 3004 3005 /* 3006 * Sleeping on runningbufspace while holding 3007 * vnode lock leads to deadlock. 3008 */ 3009 if (curproc == bufdaemonproc && 3010 runningbufspace > hirunningspace) 3011 waitrunningbufspace(); 3012 continue; 3013 } 3014 vn_finished_write(mp); 3015 BUF_UNLOCK(bp); 3016 } 3017 mtx_lock(&bqdirty); 3018 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 3019 mtx_unlock(&bqdirty); 3020 free(sentinel, M_TEMP); 3021 return (flushed); 3022 } 3023 3024 /* 3025 * Check to see if a block is currently memory resident. 3026 */ 3027 struct buf * 3028 incore(struct bufobj *bo, daddr_t blkno) 3029 { 3030 struct buf *bp; 3031 3032 BO_RLOCK(bo); 3033 bp = gbincore(bo, blkno); 3034 BO_RUNLOCK(bo); 3035 return (bp); 3036 } 3037 3038 /* 3039 * Returns true if no I/O is needed to access the 3040 * associated VM object. This is like incore except 3041 * it also hunts around in the VM system for the data. 3042 */ 3043 3044 static int 3045 inmem(struct vnode * vp, daddr_t blkno) 3046 { 3047 vm_object_t obj; 3048 vm_offset_t toff, tinc, size; 3049 vm_page_t m; 3050 vm_ooffset_t off; 3051 3052 ASSERT_VOP_LOCKED(vp, "inmem"); 3053 3054 if (incore(&vp->v_bufobj, blkno)) 3055 return 1; 3056 if (vp->v_mount == NULL) 3057 return 0; 3058 obj = vp->v_object; 3059 if (obj == NULL) 3060 return (0); 3061 3062 size = PAGE_SIZE; 3063 if (size > vp->v_mount->mnt_stat.f_iosize) 3064 size = vp->v_mount->mnt_stat.f_iosize; 3065 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 3066 3067 VM_OBJECT_RLOCK(obj); 3068 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 3069 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 3070 if (!m) 3071 goto notinmem; 3072 tinc = size; 3073 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 3074 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 3075 if (vm_page_is_valid(m, 3076 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 3077 goto notinmem; 3078 } 3079 VM_OBJECT_RUNLOCK(obj); 3080 return 1; 3081 3082 notinmem: 3083 VM_OBJECT_RUNLOCK(obj); 3084 return (0); 3085 } 3086 3087 /* 3088 * Set the dirty range for a buffer based on the status of the dirty 3089 * bits in the pages comprising the buffer. The range is limited 3090 * to the size of the buffer. 3091 * 3092 * Tell the VM system that the pages associated with this buffer 3093 * are clean. This is used for delayed writes where the data is 3094 * going to go to disk eventually without additional VM intevention. 3095 * 3096 * Note that while we only really need to clean through to b_bcount, we 3097 * just go ahead and clean through to b_bufsize. 3098 */ 3099 static void 3100 vfs_clean_pages_dirty_buf(struct buf *bp) 3101 { 3102 vm_ooffset_t foff, noff, eoff; 3103 vm_page_t m; 3104 int i; 3105 3106 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 3107 return; 3108 3109 foff = bp->b_offset; 3110 KASSERT(bp->b_offset != NOOFFSET, 3111 ("vfs_clean_pages_dirty_buf: no buffer offset")); 3112 3113 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 3114 vfs_drain_busy_pages(bp); 3115 vfs_setdirty_locked_object(bp); 3116 for (i = 0; i < bp->b_npages; i++) { 3117 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3118 eoff = noff; 3119 if (eoff > bp->b_offset + bp->b_bufsize) 3120 eoff = bp->b_offset + bp->b_bufsize; 3121 m = bp->b_pages[i]; 3122 vfs_page_set_validclean(bp, foff, m); 3123 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3124 foff = noff; 3125 } 3126 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 3127 } 3128 3129 static void 3130 vfs_setdirty_locked_object(struct buf *bp) 3131 { 3132 vm_object_t object; 3133 int i; 3134 3135 object = bp->b_bufobj->bo_object; 3136 VM_OBJECT_ASSERT_WLOCKED(object); 3137 3138 /* 3139 * We qualify the scan for modified pages on whether the 3140 * object has been flushed yet. 3141 */ 3142 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) { 3143 vm_offset_t boffset; 3144 vm_offset_t eoffset; 3145 3146 /* 3147 * test the pages to see if they have been modified directly 3148 * by users through the VM system. 3149 */ 3150 for (i = 0; i < bp->b_npages; i++) 3151 vm_page_test_dirty(bp->b_pages[i]); 3152 3153 /* 3154 * Calculate the encompassing dirty range, boffset and eoffset, 3155 * (eoffset - boffset) bytes. 3156 */ 3157 3158 for (i = 0; i < bp->b_npages; i++) { 3159 if (bp->b_pages[i]->dirty) 3160 break; 3161 } 3162 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3163 3164 for (i = bp->b_npages - 1; i >= 0; --i) { 3165 if (bp->b_pages[i]->dirty) { 3166 break; 3167 } 3168 } 3169 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3170 3171 /* 3172 * Fit it to the buffer. 3173 */ 3174 3175 if (eoffset > bp->b_bcount) 3176 eoffset = bp->b_bcount; 3177 3178 /* 3179 * If we have a good dirty range, merge with the existing 3180 * dirty range. 3181 */ 3182 3183 if (boffset < eoffset) { 3184 if (bp->b_dirtyoff > boffset) 3185 bp->b_dirtyoff = boffset; 3186 if (bp->b_dirtyend < eoffset) 3187 bp->b_dirtyend = eoffset; 3188 } 3189 } 3190 } 3191 3192 /* 3193 * Allocate the KVA mapping for an existing buffer. 3194 * If an unmapped buffer is provided but a mapped buffer is requested, take 3195 * also care to properly setup mappings between pages and KVA. 3196 */ 3197 static void 3198 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags) 3199 { 3200 struct buf *scratch_bp; 3201 int bsize, maxsize, need_mapping, need_kva; 3202 off_t offset; 3203 3204 need_mapping = bp->b_data == unmapped_buf && 3205 (gbflags & GB_UNMAPPED) == 0; 3206 need_kva = bp->b_kvabase == unmapped_buf && 3207 bp->b_data == unmapped_buf && 3208 (gbflags & GB_KVAALLOC) != 0; 3209 if (!need_mapping && !need_kva) 3210 return; 3211 3212 BUF_CHECK_UNMAPPED(bp); 3213 3214 if (need_mapping && bp->b_kvabase != unmapped_buf) { 3215 /* 3216 * Buffer is not mapped, but the KVA was already 3217 * reserved at the time of the instantiation. Use the 3218 * allocated space. 3219 */ 3220 goto has_addr; 3221 } 3222 3223 /* 3224 * Calculate the amount of the address space we would reserve 3225 * if the buffer was mapped. 3226 */ 3227 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize; 3228 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3229 offset = blkno * bsize; 3230 maxsize = size + (offset & PAGE_MASK); 3231 maxsize = imax(maxsize, bsize); 3232 3233 mapping_loop: 3234 if (bufkvaalloc(bp, maxsize, gbflags)) { 3235 /* 3236 * Request defragmentation. getnewbuf() returns us the 3237 * allocated space by the scratch buffer KVA. 3238 */ 3239 scratch_bp = getnewbuf(bp->b_vp, 0, 0, size, maxsize, gbflags | 3240 (GB_UNMAPPED | GB_KVAALLOC)); 3241 if (scratch_bp == NULL) { 3242 if ((gbflags & GB_NOWAIT_BD) != 0) { 3243 /* 3244 * XXXKIB: defragmentation cannot 3245 * succeed, not sure what else to do. 3246 */ 3247 panic("GB_NOWAIT_BD and GB_UNMAPPED %p", bp); 3248 } 3249 atomic_add_int(&mappingrestarts, 1); 3250 goto mapping_loop; 3251 } 3252 KASSERT(scratch_bp->b_kvabase != unmapped_buf, 3253 ("scratch bp has no KVA %p", scratch_bp)); 3254 /* Grab pointers. */ 3255 bp->b_kvabase = scratch_bp->b_kvabase; 3256 bp->b_kvasize = scratch_bp->b_kvasize; 3257 bp->b_data = scratch_bp->b_data; 3258 3259 /* Get rid of the scratch buffer. */ 3260 scratch_bp->b_kvasize = 0; 3261 scratch_bp->b_flags |= B_INVAL; 3262 scratch_bp->b_data = scratch_bp->b_kvabase = unmapped_buf; 3263 brelse(scratch_bp); 3264 } 3265 has_addr: 3266 if (need_mapping) { 3267 /* b_offset is handled by bpmap_qenter. */ 3268 bp->b_data = bp->b_kvabase; 3269 BUF_CHECK_MAPPED(bp); 3270 bpmap_qenter(bp); 3271 } 3272 } 3273 3274 /* 3275 * getblk: 3276 * 3277 * Get a block given a specified block and offset into a file/device. 3278 * The buffers B_DONE bit will be cleared on return, making it almost 3279 * ready for an I/O initiation. B_INVAL may or may not be set on 3280 * return. The caller should clear B_INVAL prior to initiating a 3281 * READ. 3282 * 3283 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 3284 * an existing buffer. 3285 * 3286 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 3287 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 3288 * and then cleared based on the backing VM. If the previous buffer is 3289 * non-0-sized but invalid, B_CACHE will be cleared. 3290 * 3291 * If getblk() must create a new buffer, the new buffer is returned with 3292 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 3293 * case it is returned with B_INVAL clear and B_CACHE set based on the 3294 * backing VM. 3295 * 3296 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 3297 * B_CACHE bit is clear. 3298 * 3299 * What this means, basically, is that the caller should use B_CACHE to 3300 * determine whether the buffer is fully valid or not and should clear 3301 * B_INVAL prior to issuing a read. If the caller intends to validate 3302 * the buffer by loading its data area with something, the caller needs 3303 * to clear B_INVAL. If the caller does this without issuing an I/O, 3304 * the caller should set B_CACHE ( as an optimization ), else the caller 3305 * should issue the I/O and biodone() will set B_CACHE if the I/O was 3306 * a write attempt or if it was a successfull read. If the caller 3307 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 3308 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 3309 */ 3310 struct buf * 3311 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3312 int flags) 3313 { 3314 struct buf *bp; 3315 struct bufobj *bo; 3316 int bsize, error, maxsize, vmio; 3317 off_t offset; 3318 3319 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 3320 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3321 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3322 ASSERT_VOP_LOCKED(vp, "getblk"); 3323 if (size > MAXBCACHEBUF) 3324 panic("getblk: size(%d) > MAXBCACHEBUF(%d)\n", size, 3325 MAXBCACHEBUF); 3326 if (!unmapped_buf_allowed) 3327 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3328 3329 bo = &vp->v_bufobj; 3330 loop: 3331 BO_RLOCK(bo); 3332 bp = gbincore(bo, blkno); 3333 if (bp != NULL) { 3334 int lockflags; 3335 /* 3336 * Buffer is in-core. If the buffer is not busy nor managed, 3337 * it must be on a queue. 3338 */ 3339 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 3340 3341 if (flags & GB_LOCK_NOWAIT) 3342 lockflags |= LK_NOWAIT; 3343 3344 error = BUF_TIMELOCK(bp, lockflags, 3345 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo); 3346 3347 /* 3348 * If we slept and got the lock we have to restart in case 3349 * the buffer changed identities. 3350 */ 3351 if (error == ENOLCK) 3352 goto loop; 3353 /* We timed out or were interrupted. */ 3354 else if (error) 3355 return (NULL); 3356 /* If recursed, assume caller knows the rules. */ 3357 else if (BUF_LOCKRECURSED(bp)) 3358 goto end; 3359 3360 /* 3361 * The buffer is locked. B_CACHE is cleared if the buffer is 3362 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 3363 * and for a VMIO buffer B_CACHE is adjusted according to the 3364 * backing VM cache. 3365 */ 3366 if (bp->b_flags & B_INVAL) 3367 bp->b_flags &= ~B_CACHE; 3368 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 3369 bp->b_flags |= B_CACHE; 3370 if (bp->b_flags & B_MANAGED) 3371 MPASS(bp->b_qindex == QUEUE_NONE); 3372 else 3373 bremfree(bp); 3374 3375 /* 3376 * check for size inconsistencies for non-VMIO case. 3377 */ 3378 if (bp->b_bcount != size) { 3379 if ((bp->b_flags & B_VMIO) == 0 || 3380 (size > bp->b_kvasize)) { 3381 if (bp->b_flags & B_DELWRI) { 3382 /* 3383 * If buffer is pinned and caller does 3384 * not want sleep waiting for it to be 3385 * unpinned, bail out 3386 * */ 3387 if (bp->b_pin_count > 0) { 3388 if (flags & GB_LOCK_NOWAIT) { 3389 bqrelse(bp); 3390 return (NULL); 3391 } else { 3392 bunpin_wait(bp); 3393 } 3394 } 3395 bp->b_flags |= B_NOCACHE; 3396 bwrite(bp); 3397 } else { 3398 if (LIST_EMPTY(&bp->b_dep)) { 3399 bp->b_flags |= B_RELBUF; 3400 brelse(bp); 3401 } else { 3402 bp->b_flags |= B_NOCACHE; 3403 bwrite(bp); 3404 } 3405 } 3406 goto loop; 3407 } 3408 } 3409 3410 /* 3411 * Handle the case of unmapped buffer which should 3412 * become mapped, or the buffer for which KVA 3413 * reservation is requested. 3414 */ 3415 bp_unmapped_get_kva(bp, blkno, size, flags); 3416 3417 /* 3418 * If the size is inconsistant in the VMIO case, we can resize 3419 * the buffer. This might lead to B_CACHE getting set or 3420 * cleared. If the size has not changed, B_CACHE remains 3421 * unchanged from its previous state. 3422 */ 3423 allocbuf(bp, size); 3424 3425 KASSERT(bp->b_offset != NOOFFSET, 3426 ("getblk: no buffer offset")); 3427 3428 /* 3429 * A buffer with B_DELWRI set and B_CACHE clear must 3430 * be committed before we can return the buffer in 3431 * order to prevent the caller from issuing a read 3432 * ( due to B_CACHE not being set ) and overwriting 3433 * it. 3434 * 3435 * Most callers, including NFS and FFS, need this to 3436 * operate properly either because they assume they 3437 * can issue a read if B_CACHE is not set, or because 3438 * ( for example ) an uncached B_DELWRI might loop due 3439 * to softupdates re-dirtying the buffer. In the latter 3440 * case, B_CACHE is set after the first write completes, 3441 * preventing further loops. 3442 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 3443 * above while extending the buffer, we cannot allow the 3444 * buffer to remain with B_CACHE set after the write 3445 * completes or it will represent a corrupt state. To 3446 * deal with this we set B_NOCACHE to scrap the buffer 3447 * after the write. 3448 * 3449 * We might be able to do something fancy, like setting 3450 * B_CACHE in bwrite() except if B_DELWRI is already set, 3451 * so the below call doesn't set B_CACHE, but that gets real 3452 * confusing. This is much easier. 3453 */ 3454 3455 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 3456 bp->b_flags |= B_NOCACHE; 3457 bwrite(bp); 3458 goto loop; 3459 } 3460 bp->b_flags &= ~B_DONE; 3461 } else { 3462 /* 3463 * Buffer is not in-core, create new buffer. The buffer 3464 * returned by getnewbuf() is locked. Note that the returned 3465 * buffer is also considered valid (not marked B_INVAL). 3466 */ 3467 BO_RUNLOCK(bo); 3468 /* 3469 * If the user does not want us to create the buffer, bail out 3470 * here. 3471 */ 3472 if (flags & GB_NOCREAT) 3473 return NULL; 3474 if (numfreebuffers == 0 && TD_IS_IDLETHREAD(curthread)) 3475 return NULL; 3476 3477 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize; 3478 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3479 offset = blkno * bsize; 3480 vmio = vp->v_object != NULL; 3481 if (vmio) { 3482 maxsize = size + (offset & PAGE_MASK); 3483 } else { 3484 maxsize = size; 3485 /* Do not allow non-VMIO notmapped buffers. */ 3486 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3487 } 3488 maxsize = imax(maxsize, bsize); 3489 3490 bp = getnewbuf(vp, slpflag, slptimeo, size, maxsize, flags); 3491 if (bp == NULL) { 3492 if (slpflag || slptimeo) 3493 return NULL; 3494 goto loop; 3495 } 3496 3497 /* 3498 * This code is used to make sure that a buffer is not 3499 * created while the getnewbuf routine is blocked. 3500 * This can be a problem whether the vnode is locked or not. 3501 * If the buffer is created out from under us, we have to 3502 * throw away the one we just created. 3503 * 3504 * Note: this must occur before we associate the buffer 3505 * with the vp especially considering limitations in 3506 * the splay tree implementation when dealing with duplicate 3507 * lblkno's. 3508 */ 3509 BO_LOCK(bo); 3510 if (gbincore(bo, blkno)) { 3511 BO_UNLOCK(bo); 3512 bp->b_flags |= B_INVAL; 3513 brelse(bp); 3514 goto loop; 3515 } 3516 3517 /* 3518 * Insert the buffer into the hash, so that it can 3519 * be found by incore. 3520 */ 3521 bp->b_blkno = bp->b_lblkno = blkno; 3522 bp->b_offset = offset; 3523 bgetvp(vp, bp); 3524 BO_UNLOCK(bo); 3525 3526 /* 3527 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 3528 * buffer size starts out as 0, B_CACHE will be set by 3529 * allocbuf() for the VMIO case prior to it testing the 3530 * backing store for validity. 3531 */ 3532 3533 if (vmio) { 3534 bp->b_flags |= B_VMIO; 3535 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 3536 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 3537 bp, vp->v_object, bp->b_bufobj->bo_object)); 3538 } else { 3539 bp->b_flags &= ~B_VMIO; 3540 KASSERT(bp->b_bufobj->bo_object == NULL, 3541 ("ARGH! has b_bufobj->bo_object %p %p\n", 3542 bp, bp->b_bufobj->bo_object)); 3543 BUF_CHECK_MAPPED(bp); 3544 } 3545 3546 allocbuf(bp, size); 3547 bp->b_flags &= ~B_DONE; 3548 } 3549 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 3550 BUF_ASSERT_HELD(bp); 3551 end: 3552 KASSERT(bp->b_bufobj == bo, 3553 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 3554 return (bp); 3555 } 3556 3557 /* 3558 * Get an empty, disassociated buffer of given size. The buffer is initially 3559 * set to B_INVAL. 3560 */ 3561 struct buf * 3562 geteblk(int size, int flags) 3563 { 3564 struct buf *bp; 3565 int maxsize; 3566 3567 maxsize = (size + BKVAMASK) & ~BKVAMASK; 3568 while ((bp = getnewbuf(NULL, 0, 0, size, maxsize, flags)) == NULL) { 3569 if ((flags & GB_NOWAIT_BD) && 3570 (curthread->td_pflags & TDP_BUFNEED) != 0) 3571 return (NULL); 3572 } 3573 allocbuf(bp, size); 3574 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 3575 BUF_ASSERT_HELD(bp); 3576 return (bp); 3577 } 3578 3579 /* 3580 * Truncate the backing store for a non-vmio buffer. 3581 */ 3582 static void 3583 vfs_nonvmio_truncate(struct buf *bp, int newbsize) 3584 { 3585 3586 if (bp->b_flags & B_MALLOC) { 3587 /* 3588 * malloced buffers are not shrunk 3589 */ 3590 if (newbsize == 0) { 3591 bufmallocadjust(bp, 0); 3592 free(bp->b_data, M_BIOBUF); 3593 bp->b_data = bp->b_kvabase; 3594 bp->b_flags &= ~B_MALLOC; 3595 } 3596 return; 3597 } 3598 vm_hold_free_pages(bp, newbsize); 3599 bufspaceadjust(bp, newbsize); 3600 } 3601 3602 /* 3603 * Extend the backing for a non-VMIO buffer. 3604 */ 3605 static void 3606 vfs_nonvmio_extend(struct buf *bp, int newbsize) 3607 { 3608 caddr_t origbuf; 3609 int origbufsize; 3610 3611 /* 3612 * We only use malloced memory on the first allocation. 3613 * and revert to page-allocated memory when the buffer 3614 * grows. 3615 * 3616 * There is a potential smp race here that could lead 3617 * to bufmallocspace slightly passing the max. It 3618 * is probably extremely rare and not worth worrying 3619 * over. 3620 */ 3621 if (bp->b_bufsize == 0 && newbsize <= PAGE_SIZE/2 && 3622 bufmallocspace < maxbufmallocspace) { 3623 bp->b_data = malloc(newbsize, M_BIOBUF, M_WAITOK); 3624 bp->b_flags |= B_MALLOC; 3625 bufmallocadjust(bp, newbsize); 3626 return; 3627 } 3628 3629 /* 3630 * If the buffer is growing on its other-than-first 3631 * allocation then we revert to the page-allocation 3632 * scheme. 3633 */ 3634 origbuf = NULL; 3635 origbufsize = 0; 3636 if (bp->b_flags & B_MALLOC) { 3637 origbuf = bp->b_data; 3638 origbufsize = bp->b_bufsize; 3639 bp->b_data = bp->b_kvabase; 3640 bufmallocadjust(bp, 0); 3641 bp->b_flags &= ~B_MALLOC; 3642 newbsize = round_page(newbsize); 3643 } 3644 vm_hold_load_pages(bp, (vm_offset_t) bp->b_data + bp->b_bufsize, 3645 (vm_offset_t) bp->b_data + newbsize); 3646 if (origbuf != NULL) { 3647 bcopy(origbuf, bp->b_data, origbufsize); 3648 free(origbuf, M_BIOBUF); 3649 } 3650 bufspaceadjust(bp, newbsize); 3651 } 3652 3653 /* 3654 * This code constitutes the buffer memory from either anonymous system 3655 * memory (in the case of non-VMIO operations) or from an associated 3656 * VM object (in the case of VMIO operations). This code is able to 3657 * resize a buffer up or down. 3658 * 3659 * Note that this code is tricky, and has many complications to resolve 3660 * deadlock or inconsistant data situations. Tread lightly!!! 3661 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 3662 * the caller. Calling this code willy nilly can result in the loss of data. 3663 * 3664 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 3665 * B_CACHE for the non-VMIO case. 3666 */ 3667 int 3668 allocbuf(struct buf *bp, int size) 3669 { 3670 int newbsize; 3671 3672 BUF_ASSERT_HELD(bp); 3673 3674 if (bp->b_bcount == size) 3675 return (1); 3676 3677 if (bp->b_kvasize != 0 && bp->b_kvasize < size) 3678 panic("allocbuf: buffer too small"); 3679 3680 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3681 if ((bp->b_flags & B_VMIO) == 0) { 3682 if ((bp->b_flags & B_MALLOC) == 0) 3683 newbsize = round_page(newbsize); 3684 /* 3685 * Just get anonymous memory from the kernel. Don't 3686 * mess with B_CACHE. 3687 */ 3688 if (newbsize < bp->b_bufsize) 3689 vfs_nonvmio_truncate(bp, newbsize); 3690 else if (newbsize > bp->b_bufsize) 3691 vfs_nonvmio_extend(bp, newbsize); 3692 } else { 3693 int desiredpages; 3694 3695 desiredpages = (size == 0) ? 0 : 3696 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 3697 3698 if (bp->b_flags & B_MALLOC) 3699 panic("allocbuf: VMIO buffer can't be malloced"); 3700 /* 3701 * Set B_CACHE initially if buffer is 0 length or will become 3702 * 0-length. 3703 */ 3704 if (size == 0 || bp->b_bufsize == 0) 3705 bp->b_flags |= B_CACHE; 3706 3707 if (newbsize < bp->b_bufsize) 3708 vfs_vmio_truncate(bp, desiredpages); 3709 /* XXX This looks as if it should be newbsize > b_bufsize */ 3710 else if (size > bp->b_bcount) 3711 vfs_vmio_extend(bp, desiredpages, size); 3712 bufspaceadjust(bp, newbsize); 3713 } 3714 bp->b_bcount = size; /* requested buffer size. */ 3715 return (1); 3716 } 3717 3718 extern int inflight_transient_maps; 3719 3720 void 3721 biodone(struct bio *bp) 3722 { 3723 struct mtx *mtxp; 3724 void (*done)(struct bio *); 3725 vm_offset_t start, end; 3726 3727 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) { 3728 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING; 3729 bp->bio_flags |= BIO_UNMAPPED; 3730 start = trunc_page((vm_offset_t)bp->bio_data); 3731 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length); 3732 bp->bio_data = unmapped_buf; 3733 pmap_qremove(start, OFF_TO_IDX(end - start)); 3734 vmem_free(transient_arena, start, end - start); 3735 atomic_add_int(&inflight_transient_maps, -1); 3736 } 3737 done = bp->bio_done; 3738 if (done == NULL) { 3739 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3740 mtx_lock(mtxp); 3741 bp->bio_flags |= BIO_DONE; 3742 wakeup(bp); 3743 mtx_unlock(mtxp); 3744 } else { 3745 bp->bio_flags |= BIO_DONE; 3746 done(bp); 3747 } 3748 } 3749 3750 /* 3751 * Wait for a BIO to finish. 3752 */ 3753 int 3754 biowait(struct bio *bp, const char *wchan) 3755 { 3756 struct mtx *mtxp; 3757 3758 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3759 mtx_lock(mtxp); 3760 while ((bp->bio_flags & BIO_DONE) == 0) 3761 msleep(bp, mtxp, PRIBIO, wchan, 0); 3762 mtx_unlock(mtxp); 3763 if (bp->bio_error != 0) 3764 return (bp->bio_error); 3765 if (!(bp->bio_flags & BIO_ERROR)) 3766 return (0); 3767 return (EIO); 3768 } 3769 3770 void 3771 biofinish(struct bio *bp, struct devstat *stat, int error) 3772 { 3773 3774 if (error) { 3775 bp->bio_error = error; 3776 bp->bio_flags |= BIO_ERROR; 3777 } 3778 if (stat != NULL) 3779 devstat_end_transaction_bio(stat, bp); 3780 biodone(bp); 3781 } 3782 3783 /* 3784 * bufwait: 3785 * 3786 * Wait for buffer I/O completion, returning error status. The buffer 3787 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3788 * error and cleared. 3789 */ 3790 int 3791 bufwait(struct buf *bp) 3792 { 3793 if (bp->b_iocmd == BIO_READ) 3794 bwait(bp, PRIBIO, "biord"); 3795 else 3796 bwait(bp, PRIBIO, "biowr"); 3797 if (bp->b_flags & B_EINTR) { 3798 bp->b_flags &= ~B_EINTR; 3799 return (EINTR); 3800 } 3801 if (bp->b_ioflags & BIO_ERROR) { 3802 return (bp->b_error ? bp->b_error : EIO); 3803 } else { 3804 return (0); 3805 } 3806 } 3807 3808 /* 3809 * bufdone: 3810 * 3811 * Finish I/O on a buffer, optionally calling a completion function. 3812 * This is usually called from an interrupt so process blocking is 3813 * not allowed. 3814 * 3815 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3816 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3817 * assuming B_INVAL is clear. 3818 * 3819 * For the VMIO case, we set B_CACHE if the op was a read and no 3820 * read error occured, or if the op was a write. B_CACHE is never 3821 * set if the buffer is invalid or otherwise uncacheable. 3822 * 3823 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3824 * initiator to leave B_INVAL set to brelse the buffer out of existance 3825 * in the biodone routine. 3826 */ 3827 void 3828 bufdone(struct buf *bp) 3829 { 3830 struct bufobj *dropobj; 3831 void (*biodone)(struct buf *); 3832 3833 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 3834 dropobj = NULL; 3835 3836 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 3837 BUF_ASSERT_HELD(bp); 3838 3839 runningbufwakeup(bp); 3840 if (bp->b_iocmd == BIO_WRITE) 3841 dropobj = bp->b_bufobj; 3842 /* call optional completion function if requested */ 3843 if (bp->b_iodone != NULL) { 3844 biodone = bp->b_iodone; 3845 bp->b_iodone = NULL; 3846 (*biodone) (bp); 3847 if (dropobj) 3848 bufobj_wdrop(dropobj); 3849 return; 3850 } 3851 3852 bufdone_finish(bp); 3853 3854 if (dropobj) 3855 bufobj_wdrop(dropobj); 3856 } 3857 3858 void 3859 bufdone_finish(struct buf *bp) 3860 { 3861 BUF_ASSERT_HELD(bp); 3862 3863 if (!LIST_EMPTY(&bp->b_dep)) 3864 buf_complete(bp); 3865 3866 if (bp->b_flags & B_VMIO) { 3867 /* 3868 * Set B_CACHE if the op was a normal read and no error 3869 * occured. B_CACHE is set for writes in the b*write() 3870 * routines. 3871 */ 3872 if (bp->b_iocmd == BIO_READ && 3873 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 3874 !(bp->b_ioflags & BIO_ERROR)) 3875 bp->b_flags |= B_CACHE; 3876 vfs_vmio_iodone(bp); 3877 } 3878 3879 /* 3880 * For asynchronous completions, release the buffer now. The brelse 3881 * will do a wakeup there if necessary - so no need to do a wakeup 3882 * here in the async case. The sync case always needs to do a wakeup. 3883 */ 3884 if (bp->b_flags & B_ASYNC) { 3885 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || 3886 (bp->b_ioflags & BIO_ERROR)) 3887 brelse(bp); 3888 else 3889 bqrelse(bp); 3890 } else 3891 bdone(bp); 3892 } 3893 3894 /* 3895 * This routine is called in lieu of iodone in the case of 3896 * incomplete I/O. This keeps the busy status for pages 3897 * consistant. 3898 */ 3899 void 3900 vfs_unbusy_pages(struct buf *bp) 3901 { 3902 int i; 3903 vm_object_t obj; 3904 vm_page_t m; 3905 3906 runningbufwakeup(bp); 3907 if (!(bp->b_flags & B_VMIO)) 3908 return; 3909 3910 obj = bp->b_bufobj->bo_object; 3911 VM_OBJECT_WLOCK(obj); 3912 for (i = 0; i < bp->b_npages; i++) { 3913 m = bp->b_pages[i]; 3914 if (m == bogus_page) { 3915 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 3916 if (!m) 3917 panic("vfs_unbusy_pages: page missing\n"); 3918 bp->b_pages[i] = m; 3919 if (buf_mapped(bp)) { 3920 BUF_CHECK_MAPPED(bp); 3921 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3922 bp->b_pages, bp->b_npages); 3923 } else 3924 BUF_CHECK_UNMAPPED(bp); 3925 } 3926 vm_object_pip_subtract(obj, 1); 3927 vm_page_sunbusy(m); 3928 } 3929 vm_object_pip_wakeupn(obj, 0); 3930 VM_OBJECT_WUNLOCK(obj); 3931 } 3932 3933 /* 3934 * vfs_page_set_valid: 3935 * 3936 * Set the valid bits in a page based on the supplied offset. The 3937 * range is restricted to the buffer's size. 3938 * 3939 * This routine is typically called after a read completes. 3940 */ 3941 static void 3942 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3943 { 3944 vm_ooffset_t eoff; 3945 3946 /* 3947 * Compute the end offset, eoff, such that [off, eoff) does not span a 3948 * page boundary and eoff is not greater than the end of the buffer. 3949 * The end of the buffer, in this case, is our file EOF, not the 3950 * allocation size of the buffer. 3951 */ 3952 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 3953 if (eoff > bp->b_offset + bp->b_bcount) 3954 eoff = bp->b_offset + bp->b_bcount; 3955 3956 /* 3957 * Set valid range. This is typically the entire buffer and thus the 3958 * entire page. 3959 */ 3960 if (eoff > off) 3961 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off); 3962 } 3963 3964 /* 3965 * vfs_page_set_validclean: 3966 * 3967 * Set the valid bits and clear the dirty bits in a page based on the 3968 * supplied offset. The range is restricted to the buffer's size. 3969 */ 3970 static void 3971 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3972 { 3973 vm_ooffset_t soff, eoff; 3974 3975 /* 3976 * Start and end offsets in buffer. eoff - soff may not cross a 3977 * page boundry or cross the end of the buffer. The end of the 3978 * buffer, in this case, is our file EOF, not the allocation size 3979 * of the buffer. 3980 */ 3981 soff = off; 3982 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3983 if (eoff > bp->b_offset + bp->b_bcount) 3984 eoff = bp->b_offset + bp->b_bcount; 3985 3986 /* 3987 * Set valid range. This is typically the entire buffer and thus the 3988 * entire page. 3989 */ 3990 if (eoff > soff) { 3991 vm_page_set_validclean( 3992 m, 3993 (vm_offset_t) (soff & PAGE_MASK), 3994 (vm_offset_t) (eoff - soff) 3995 ); 3996 } 3997 } 3998 3999 /* 4000 * Ensure that all buffer pages are not exclusive busied. If any page is 4001 * exclusive busy, drain it. 4002 */ 4003 void 4004 vfs_drain_busy_pages(struct buf *bp) 4005 { 4006 vm_page_t m; 4007 int i, last_busied; 4008 4009 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object); 4010 last_busied = 0; 4011 for (i = 0; i < bp->b_npages; i++) { 4012 m = bp->b_pages[i]; 4013 if (vm_page_xbusied(m)) { 4014 for (; last_busied < i; last_busied++) 4015 vm_page_sbusy(bp->b_pages[last_busied]); 4016 while (vm_page_xbusied(m)) { 4017 vm_page_lock(m); 4018 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4019 vm_page_busy_sleep(m, "vbpage"); 4020 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4021 } 4022 } 4023 } 4024 for (i = 0; i < last_busied; i++) 4025 vm_page_sunbusy(bp->b_pages[i]); 4026 } 4027 4028 /* 4029 * This routine is called before a device strategy routine. 4030 * It is used to tell the VM system that paging I/O is in 4031 * progress, and treat the pages associated with the buffer 4032 * almost as being exclusive busy. Also the object paging_in_progress 4033 * flag is handled to make sure that the object doesn't become 4034 * inconsistant. 4035 * 4036 * Since I/O has not been initiated yet, certain buffer flags 4037 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 4038 * and should be ignored. 4039 */ 4040 void 4041 vfs_busy_pages(struct buf *bp, int clear_modify) 4042 { 4043 int i, bogus; 4044 vm_object_t obj; 4045 vm_ooffset_t foff; 4046 vm_page_t m; 4047 4048 if (!(bp->b_flags & B_VMIO)) 4049 return; 4050 4051 obj = bp->b_bufobj->bo_object; 4052 foff = bp->b_offset; 4053 KASSERT(bp->b_offset != NOOFFSET, 4054 ("vfs_busy_pages: no buffer offset")); 4055 VM_OBJECT_WLOCK(obj); 4056 vfs_drain_busy_pages(bp); 4057 if (bp->b_bufsize != 0) 4058 vfs_setdirty_locked_object(bp); 4059 bogus = 0; 4060 for (i = 0; i < bp->b_npages; i++) { 4061 m = bp->b_pages[i]; 4062 4063 if ((bp->b_flags & B_CLUSTER) == 0) { 4064 vm_object_pip_add(obj, 1); 4065 vm_page_sbusy(m); 4066 } 4067 /* 4068 * When readying a buffer for a read ( i.e 4069 * clear_modify == 0 ), it is important to do 4070 * bogus_page replacement for valid pages in 4071 * partially instantiated buffers. Partially 4072 * instantiated buffers can, in turn, occur when 4073 * reconstituting a buffer from its VM backing store 4074 * base. We only have to do this if B_CACHE is 4075 * clear ( which causes the I/O to occur in the 4076 * first place ). The replacement prevents the read 4077 * I/O from overwriting potentially dirty VM-backed 4078 * pages. XXX bogus page replacement is, uh, bogus. 4079 * It may not work properly with small-block devices. 4080 * We need to find a better way. 4081 */ 4082 if (clear_modify) { 4083 pmap_remove_write(m); 4084 vfs_page_set_validclean(bp, foff, m); 4085 } else if (m->valid == VM_PAGE_BITS_ALL && 4086 (bp->b_flags & B_CACHE) == 0) { 4087 bp->b_pages[i] = bogus_page; 4088 bogus++; 4089 } 4090 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4091 } 4092 VM_OBJECT_WUNLOCK(obj); 4093 if (bogus && buf_mapped(bp)) { 4094 BUF_CHECK_MAPPED(bp); 4095 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4096 bp->b_pages, bp->b_npages); 4097 } 4098 } 4099 4100 /* 4101 * vfs_bio_set_valid: 4102 * 4103 * Set the range within the buffer to valid. The range is 4104 * relative to the beginning of the buffer, b_offset. Note that 4105 * b_offset itself may be offset from the beginning of the first 4106 * page. 4107 */ 4108 void 4109 vfs_bio_set_valid(struct buf *bp, int base, int size) 4110 { 4111 int i, n; 4112 vm_page_t m; 4113 4114 if (!(bp->b_flags & B_VMIO)) 4115 return; 4116 4117 /* 4118 * Fixup base to be relative to beginning of first page. 4119 * Set initial n to be the maximum number of bytes in the 4120 * first page that can be validated. 4121 */ 4122 base += (bp->b_offset & PAGE_MASK); 4123 n = PAGE_SIZE - (base & PAGE_MASK); 4124 4125 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4126 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4127 m = bp->b_pages[i]; 4128 if (n > size) 4129 n = size; 4130 vm_page_set_valid_range(m, base & PAGE_MASK, n); 4131 base += n; 4132 size -= n; 4133 n = PAGE_SIZE; 4134 } 4135 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4136 } 4137 4138 /* 4139 * vfs_bio_clrbuf: 4140 * 4141 * If the specified buffer is a non-VMIO buffer, clear the entire 4142 * buffer. If the specified buffer is a VMIO buffer, clear and 4143 * validate only the previously invalid portions of the buffer. 4144 * This routine essentially fakes an I/O, so we need to clear 4145 * BIO_ERROR and B_INVAL. 4146 * 4147 * Note that while we only theoretically need to clear through b_bcount, 4148 * we go ahead and clear through b_bufsize. 4149 */ 4150 void 4151 vfs_bio_clrbuf(struct buf *bp) 4152 { 4153 int i, j, mask, sa, ea, slide; 4154 4155 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 4156 clrbuf(bp); 4157 return; 4158 } 4159 bp->b_flags &= ~B_INVAL; 4160 bp->b_ioflags &= ~BIO_ERROR; 4161 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4162 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 4163 (bp->b_offset & PAGE_MASK) == 0) { 4164 if (bp->b_pages[0] == bogus_page) 4165 goto unlock; 4166 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 4167 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object); 4168 if ((bp->b_pages[0]->valid & mask) == mask) 4169 goto unlock; 4170 if ((bp->b_pages[0]->valid & mask) == 0) { 4171 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize); 4172 bp->b_pages[0]->valid |= mask; 4173 goto unlock; 4174 } 4175 } 4176 sa = bp->b_offset & PAGE_MASK; 4177 slide = 0; 4178 for (i = 0; i < bp->b_npages; i++, sa = 0) { 4179 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize); 4180 ea = slide & PAGE_MASK; 4181 if (ea == 0) 4182 ea = PAGE_SIZE; 4183 if (bp->b_pages[i] == bogus_page) 4184 continue; 4185 j = sa / DEV_BSIZE; 4186 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 4187 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object); 4188 if ((bp->b_pages[i]->valid & mask) == mask) 4189 continue; 4190 if ((bp->b_pages[i]->valid & mask) == 0) 4191 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa); 4192 else { 4193 for (; sa < ea; sa += DEV_BSIZE, j++) { 4194 if ((bp->b_pages[i]->valid & (1 << j)) == 0) { 4195 pmap_zero_page_area(bp->b_pages[i], 4196 sa, DEV_BSIZE); 4197 } 4198 } 4199 } 4200 bp->b_pages[i]->valid |= mask; 4201 } 4202 unlock: 4203 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4204 bp->b_resid = 0; 4205 } 4206 4207 void 4208 vfs_bio_bzero_buf(struct buf *bp, int base, int size) 4209 { 4210 vm_page_t m; 4211 int i, n; 4212 4213 if (buf_mapped(bp)) { 4214 BUF_CHECK_MAPPED(bp); 4215 bzero(bp->b_data + base, size); 4216 } else { 4217 BUF_CHECK_UNMAPPED(bp); 4218 n = PAGE_SIZE - (base & PAGE_MASK); 4219 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4220 m = bp->b_pages[i]; 4221 if (n > size) 4222 n = size; 4223 pmap_zero_page_area(m, base & PAGE_MASK, n); 4224 base += n; 4225 size -= n; 4226 n = PAGE_SIZE; 4227 } 4228 } 4229 } 4230 4231 /* 4232 * vm_hold_load_pages and vm_hold_free_pages get pages into 4233 * a buffers address space. The pages are anonymous and are 4234 * not associated with a file object. 4235 */ 4236 static void 4237 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4238 { 4239 vm_offset_t pg; 4240 vm_page_t p; 4241 int index; 4242 4243 BUF_CHECK_MAPPED(bp); 4244 4245 to = round_page(to); 4246 from = round_page(from); 4247 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4248 4249 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 4250 tryagain: 4251 /* 4252 * note: must allocate system pages since blocking here 4253 * could interfere with paging I/O, no matter which 4254 * process we are. 4255 */ 4256 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ | 4257 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT)); 4258 if (p == NULL) { 4259 VM_WAIT; 4260 goto tryagain; 4261 } 4262 pmap_qenter(pg, &p, 1); 4263 bp->b_pages[index] = p; 4264 } 4265 bp->b_npages = index; 4266 } 4267 4268 /* Return pages associated with this buf to the vm system */ 4269 static void 4270 vm_hold_free_pages(struct buf *bp, int newbsize) 4271 { 4272 vm_offset_t from; 4273 vm_page_t p; 4274 int index, newnpages; 4275 4276 BUF_CHECK_MAPPED(bp); 4277 4278 from = round_page((vm_offset_t)bp->b_data + newbsize); 4279 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4280 if (bp->b_npages > newnpages) 4281 pmap_qremove(from, bp->b_npages - newnpages); 4282 for (index = newnpages; index < bp->b_npages; index++) { 4283 p = bp->b_pages[index]; 4284 bp->b_pages[index] = NULL; 4285 if (vm_page_sbusied(p)) 4286 printf("vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 4287 (intmax_t)bp->b_blkno, (intmax_t)bp->b_lblkno); 4288 p->wire_count--; 4289 vm_page_free(p); 4290 atomic_subtract_int(&vm_cnt.v_wire_count, 1); 4291 } 4292 bp->b_npages = newnpages; 4293 } 4294 4295 /* 4296 * Map an IO request into kernel virtual address space. 4297 * 4298 * All requests are (re)mapped into kernel VA space. 4299 * Notice that we use b_bufsize for the size of the buffer 4300 * to be mapped. b_bcount might be modified by the driver. 4301 * 4302 * Note that even if the caller determines that the address space should 4303 * be valid, a race or a smaller-file mapped into a larger space may 4304 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 4305 * check the return value. 4306 * 4307 * This function only works with pager buffers. 4308 */ 4309 int 4310 vmapbuf(struct buf *bp, int mapbuf) 4311 { 4312 vm_prot_t prot; 4313 int pidx; 4314 4315 if (bp->b_bufsize < 0) 4316 return (-1); 4317 prot = VM_PROT_READ; 4318 if (bp->b_iocmd == BIO_READ) 4319 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 4320 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 4321 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages, 4322 btoc(MAXPHYS))) < 0) 4323 return (-1); 4324 bp->b_npages = pidx; 4325 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK; 4326 if (mapbuf || !unmapped_buf_allowed) { 4327 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_pages, pidx); 4328 bp->b_data = bp->b_kvabase + bp->b_offset; 4329 } else 4330 bp->b_data = unmapped_buf; 4331 return(0); 4332 } 4333 4334 /* 4335 * Free the io map PTEs associated with this IO operation. 4336 * We also invalidate the TLB entries and restore the original b_addr. 4337 * 4338 * This function only works with pager buffers. 4339 */ 4340 void 4341 vunmapbuf(struct buf *bp) 4342 { 4343 int npages; 4344 4345 npages = bp->b_npages; 4346 if (buf_mapped(bp)) 4347 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 4348 vm_page_unhold_pages(bp->b_pages, npages); 4349 4350 bp->b_data = unmapped_buf; 4351 } 4352 4353 void 4354 bdone(struct buf *bp) 4355 { 4356 struct mtx *mtxp; 4357 4358 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4359 mtx_lock(mtxp); 4360 bp->b_flags |= B_DONE; 4361 wakeup(bp); 4362 mtx_unlock(mtxp); 4363 } 4364 4365 void 4366 bwait(struct buf *bp, u_char pri, const char *wchan) 4367 { 4368 struct mtx *mtxp; 4369 4370 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4371 mtx_lock(mtxp); 4372 while ((bp->b_flags & B_DONE) == 0) 4373 msleep(bp, mtxp, pri, wchan, 0); 4374 mtx_unlock(mtxp); 4375 } 4376 4377 int 4378 bufsync(struct bufobj *bo, int waitfor) 4379 { 4380 4381 return (VOP_FSYNC(bo->__bo_vnode, waitfor, curthread)); 4382 } 4383 4384 void 4385 bufstrategy(struct bufobj *bo, struct buf *bp) 4386 { 4387 int i = 0; 4388 struct vnode *vp; 4389 4390 vp = bp->b_vp; 4391 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 4392 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 4393 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 4394 i = VOP_STRATEGY(vp, bp); 4395 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 4396 } 4397 4398 void 4399 bufobj_wrefl(struct bufobj *bo) 4400 { 4401 4402 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4403 ASSERT_BO_WLOCKED(bo); 4404 bo->bo_numoutput++; 4405 } 4406 4407 void 4408 bufobj_wref(struct bufobj *bo) 4409 { 4410 4411 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4412 BO_LOCK(bo); 4413 bo->bo_numoutput++; 4414 BO_UNLOCK(bo); 4415 } 4416 4417 void 4418 bufobj_wdrop(struct bufobj *bo) 4419 { 4420 4421 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 4422 BO_LOCK(bo); 4423 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 4424 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 4425 bo->bo_flag &= ~BO_WWAIT; 4426 wakeup(&bo->bo_numoutput); 4427 } 4428 BO_UNLOCK(bo); 4429 } 4430 4431 int 4432 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 4433 { 4434 int error; 4435 4436 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 4437 ASSERT_BO_WLOCKED(bo); 4438 error = 0; 4439 while (bo->bo_numoutput) { 4440 bo->bo_flag |= BO_WWAIT; 4441 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo), 4442 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 4443 if (error) 4444 break; 4445 } 4446 return (error); 4447 } 4448 4449 void 4450 bpin(struct buf *bp) 4451 { 4452 struct mtx *mtxp; 4453 4454 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4455 mtx_lock(mtxp); 4456 bp->b_pin_count++; 4457 mtx_unlock(mtxp); 4458 } 4459 4460 void 4461 bunpin(struct buf *bp) 4462 { 4463 struct mtx *mtxp; 4464 4465 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4466 mtx_lock(mtxp); 4467 if (--bp->b_pin_count == 0) 4468 wakeup(bp); 4469 mtx_unlock(mtxp); 4470 } 4471 4472 void 4473 bunpin_wait(struct buf *bp) 4474 { 4475 struct mtx *mtxp; 4476 4477 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4478 mtx_lock(mtxp); 4479 while (bp->b_pin_count > 0) 4480 msleep(bp, mtxp, PRIBIO, "bwunpin", 0); 4481 mtx_unlock(mtxp); 4482 } 4483 4484 /* 4485 * Set bio_data or bio_ma for struct bio from the struct buf. 4486 */ 4487 void 4488 bdata2bio(struct buf *bp, struct bio *bip) 4489 { 4490 4491 if (!buf_mapped(bp)) { 4492 KASSERT(unmapped_buf_allowed, ("unmapped")); 4493 bip->bio_ma = bp->b_pages; 4494 bip->bio_ma_n = bp->b_npages; 4495 bip->bio_data = unmapped_buf; 4496 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 4497 bip->bio_flags |= BIO_UNMAPPED; 4498 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) / 4499 PAGE_SIZE == bp->b_npages, 4500 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset, 4501 (long long)bip->bio_length, bip->bio_ma_n)); 4502 } else { 4503 bip->bio_data = bp->b_data; 4504 bip->bio_ma = NULL; 4505 } 4506 } 4507 4508 #include "opt_ddb.h" 4509 #ifdef DDB 4510 #include <ddb/ddb.h> 4511 4512 /* DDB command to show buffer data */ 4513 DB_SHOW_COMMAND(buffer, db_show_buffer) 4514 { 4515 /* get args */ 4516 struct buf *bp = (struct buf *)addr; 4517 4518 if (!have_addr) { 4519 db_printf("usage: show buffer <addr>\n"); 4520 return; 4521 } 4522 4523 db_printf("buf at %p\n", bp); 4524 db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n", 4525 (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags, 4526 PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS); 4527 db_printf( 4528 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 4529 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, " 4530 "b_dep = %p\n", 4531 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 4532 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 4533 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first); 4534 db_printf("b_kvabase = %p, b_kvasize = %d\n", 4535 bp->b_kvabase, bp->b_kvasize); 4536 if (bp->b_npages) { 4537 int i; 4538 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 4539 for (i = 0; i < bp->b_npages; i++) { 4540 vm_page_t m; 4541 m = bp->b_pages[i]; 4542 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 4543 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 4544 if ((i + 1) < bp->b_npages) 4545 db_printf(","); 4546 } 4547 db_printf("\n"); 4548 } 4549 db_printf(" "); 4550 BUF_LOCKPRINTINFO(bp); 4551 } 4552 4553 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 4554 { 4555 struct buf *bp; 4556 int i; 4557 4558 for (i = 0; i < nbuf; i++) { 4559 bp = &buf[i]; 4560 if (BUF_ISLOCKED(bp)) { 4561 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4562 db_printf("\n"); 4563 } 4564 } 4565 } 4566 4567 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 4568 { 4569 struct vnode *vp; 4570 struct buf *bp; 4571 4572 if (!have_addr) { 4573 db_printf("usage: show vnodebufs <addr>\n"); 4574 return; 4575 } 4576 vp = (struct vnode *)addr; 4577 db_printf("Clean buffers:\n"); 4578 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 4579 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4580 db_printf("\n"); 4581 } 4582 db_printf("Dirty buffers:\n"); 4583 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 4584 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4585 db_printf("\n"); 4586 } 4587 } 4588 4589 DB_COMMAND(countfreebufs, db_coundfreebufs) 4590 { 4591 struct buf *bp; 4592 int i, used = 0, nfree = 0; 4593 4594 if (have_addr) { 4595 db_printf("usage: countfreebufs\n"); 4596 return; 4597 } 4598 4599 for (i = 0; i < nbuf; i++) { 4600 bp = &buf[i]; 4601 if ((bp->b_flags & B_INFREECNT) != 0) 4602 nfree++; 4603 else 4604 used++; 4605 } 4606 4607 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 4608 nfree + used); 4609 db_printf("numfreebuffers is %d\n", numfreebuffers); 4610 } 4611 #endif /* DDB */ 4612