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/vmem.h> 68 #include <sys/vmmeter.h> 69 #include <sys/vnode.h> 70 #include <geom/geom.h> 71 #include <vm/vm.h> 72 #include <vm/vm_param.h> 73 #include <vm/vm_kern.h> 74 #include <vm/vm_pageout.h> 75 #include <vm/vm_page.h> 76 #include <vm/vm_object.h> 77 #include <vm/vm_extern.h> 78 #include <vm/vm_map.h> 79 #include "opt_compat.h" 80 #include "opt_swap.h" 81 82 static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer"); 83 84 struct bio_ops bioops; /* I/O operation notification */ 85 86 struct buf_ops buf_ops_bio = { 87 .bop_name = "buf_ops_bio", 88 .bop_write = bufwrite, 89 .bop_strategy = bufstrategy, 90 .bop_sync = bufsync, 91 .bop_bdflush = bufbdflush, 92 }; 93 94 /* 95 * XXX buf is global because kern_shutdown.c and ffs_checkoverlap has 96 * carnal knowledge of buffers. This knowledge should be moved to vfs_bio.c. 97 */ 98 struct buf *buf; /* 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_release(struct buf *bp); 114 static int vfs_bio_clcheck(struct vnode *vp, int size, 115 daddr_t lblkno, daddr_t blkno); 116 static int buf_flush(struct vnode *vp, int); 117 static int flushbufqueues(struct vnode *, int, int); 118 static void buf_daemon(void); 119 static void bremfreel(struct buf *bp); 120 static __inline void bd_wakeup(void); 121 static int sysctl_runningspace(SYSCTL_HANDLER_ARGS); 122 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 123 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 124 static int sysctl_bufspace(SYSCTL_HANDLER_ARGS); 125 #endif 126 127 int vmiodirenable = TRUE; 128 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, 129 "Use the VM system for directory writes"); 130 long runningbufspace; 131 SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 132 "Amount of presently outstanding async buffer io"); 133 static long bufspace; 134 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 135 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 136 SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD, 137 &bufspace, 0, sysctl_bufspace, "L", "Virtual memory used for buffers"); 138 #else 139 SYSCTL_LONG(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, 140 "Physical memory used for buffers"); 141 #endif 142 static long bufkvaspace; 143 SYSCTL_LONG(_vfs, OID_AUTO, bufkvaspace, CTLFLAG_RD, &bufkvaspace, 0, 144 "Kernel virtual memory used for buffers"); 145 static long maxbufspace; 146 SYSCTL_LONG(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0, 147 "Maximum allowed value of bufspace (including buf_daemon)"); 148 static long bufmallocspace; 149 SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 150 "Amount of malloced memory for buffers"); 151 static long maxbufmallocspace; 152 SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0, 153 "Maximum amount of malloced memory for buffers"); 154 static long lobufspace; 155 SYSCTL_LONG(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0, 156 "Minimum amount of buffers we want to have"); 157 long hibufspace; 158 SYSCTL_LONG(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0, 159 "Maximum allowed value of bufspace (excluding buf_daemon)"); 160 static int bufreusecnt; 161 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0, 162 "Number of times we have reused a buffer"); 163 static int buffreekvacnt; 164 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0, 165 "Number of times we have freed the KVA space from some buffer"); 166 static int bufdefragcnt; 167 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0, 168 "Number of times we have had to repeat buffer allocation to defragment"); 169 static long lorunningspace; 170 SYSCTL_PROC(_vfs, OID_AUTO, lorunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE | 171 CTLFLAG_RW, &lorunningspace, 0, sysctl_runningspace, "L", 172 "Minimum preferred space used for in-progress I/O"); 173 static long hirunningspace; 174 SYSCTL_PROC(_vfs, OID_AUTO, hirunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE | 175 CTLFLAG_RW, &hirunningspace, 0, sysctl_runningspace, "L", 176 "Maximum amount of space to use for in-progress I/O"); 177 int dirtybufferflushes; 178 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes, 179 0, "Number of bdwrite to bawrite conversions to limit dirty buffers"); 180 int bdwriteskip; 181 SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip, 182 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk"); 183 int altbufferflushes; 184 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes, 185 0, "Number of fsync flushes to limit dirty buffers"); 186 static int recursiveflushes; 187 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes, 188 0, "Number of flushes skipped due to being recursive"); 189 static int numdirtybuffers; 190 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0, 191 "Number of buffers that are dirty (has unwritten changes) at the moment"); 192 static int lodirtybuffers; 193 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0, 194 "How many buffers we want to have free before bufdaemon can sleep"); 195 static int hidirtybuffers; 196 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0, 197 "When the number of dirty buffers is considered severe"); 198 int dirtybufthresh; 199 SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh, 200 0, "Number of bdwrite to bawrite conversions to clear dirty buffers"); 201 static int numfreebuffers; 202 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, 203 "Number of free buffers"); 204 static int lofreebuffers; 205 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0, 206 "XXX Unused"); 207 static int hifreebuffers; 208 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0, 209 "XXX Complicatedly unused"); 210 static int getnewbufcalls; 211 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0, 212 "Number of calls to getnewbuf"); 213 static int getnewbufrestarts; 214 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0, 215 "Number of times getnewbuf has had to restart a buffer aquisition"); 216 static int mappingrestarts; 217 SYSCTL_INT(_vfs, OID_AUTO, mappingrestarts, CTLFLAG_RW, &mappingrestarts, 0, 218 "Number of times getblk has had to restart a buffer mapping for " 219 "unmapped buffer"); 220 static int flushbufqtarget = 100; 221 SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0, 222 "Amount of work to do in flushbufqueues when helping bufdaemon"); 223 static long notbufdflushes; 224 SYSCTL_LONG(_vfs, OID_AUTO, notbufdflushes, CTLFLAG_RD, ¬bufdflushes, 0, 225 "Number of dirty buffer flushes done by the bufdaemon helpers"); 226 static long barrierwrites; 227 SYSCTL_LONG(_vfs, OID_AUTO, barrierwrites, CTLFLAG_RW, &barrierwrites, 0, 228 "Number of barrier writes"); 229 SYSCTL_INT(_vfs, OID_AUTO, unmapped_buf_allowed, CTLFLAG_RD, 230 &unmapped_buf_allowed, 0, 231 "Permit the use of the unmapped i/o"); 232 233 /* 234 * Lock for the non-dirty bufqueues 235 */ 236 static struct mtx_padalign bqclean; 237 238 /* 239 * Lock for the dirty queue. 240 */ 241 static struct mtx_padalign bqdirty; 242 243 /* 244 * This lock synchronizes access to bd_request. 245 */ 246 static struct mtx_padalign bdlock; 247 248 /* 249 * This lock protects the runningbufreq and synchronizes runningbufwakeup and 250 * waitrunningbufspace(). 251 */ 252 static struct mtx_padalign rbreqlock; 253 254 /* 255 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it. 256 */ 257 static struct rwlock_padalign nblock; 258 259 /* 260 * Lock that protects bdirtywait. 261 */ 262 static struct mtx_padalign bdirtylock; 263 264 /* 265 * Wakeup point for bufdaemon, as well as indicator of whether it is already 266 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it 267 * is idling. 268 */ 269 static int bd_request; 270 271 /* 272 * Request for the buf daemon to write more buffers than is indicated by 273 * lodirtybuf. This may be necessary to push out excess dependencies or 274 * defragment the address space where a simple count of the number of dirty 275 * buffers is insufficient to characterize the demand for flushing them. 276 */ 277 static int bd_speedupreq; 278 279 /* 280 * bogus page -- for I/O to/from partially complete buffers 281 * this is a temporary solution to the problem, but it is not 282 * really that bad. it would be better to split the buffer 283 * for input in the case of buffers partially already in memory, 284 * but the code is intricate enough already. 285 */ 286 vm_page_t bogus_page; 287 288 /* 289 * Synchronization (sleep/wakeup) variable for active buffer space requests. 290 * Set when wait starts, cleared prior to wakeup(). 291 * Used in runningbufwakeup() and waitrunningbufspace(). 292 */ 293 static int runningbufreq; 294 295 /* 296 * Synchronization (sleep/wakeup) variable for buffer requests. 297 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done 298 * by and/or. 299 * Used in numdirtywakeup(), bufspacewakeup(), bufcountadd(), bwillwrite(), 300 * getnewbuf(), and getblk(). 301 */ 302 static volatile int needsbuffer; 303 304 /* 305 * Synchronization for bwillwrite() waiters. 306 */ 307 static int bdirtywait; 308 309 /* 310 * Definitions for the buffer free lists. 311 */ 312 #define BUFFER_QUEUES 5 /* number of free buffer queues */ 313 314 #define QUEUE_NONE 0 /* on no queue */ 315 #define QUEUE_CLEAN 1 /* non-B_DELWRI buffers */ 316 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */ 317 #define QUEUE_EMPTYKVA 3 /* empty buffer headers w/KVA assignment */ 318 #define QUEUE_EMPTY 4 /* empty buffer headers */ 319 #define QUEUE_SENTINEL 1024 /* not an queue index, but mark for sentinel */ 320 321 /* Queues for free buffers with various properties */ 322 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } }; 323 #ifdef INVARIANTS 324 static int bq_len[BUFFER_QUEUES]; 325 #endif 326 327 /* 328 * Single global constant for BUF_WMESG, to avoid getting multiple references. 329 * buf_wmesg is referred from macros. 330 */ 331 const char *buf_wmesg = BUF_WMESG; 332 333 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 334 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ 335 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 336 337 static int 338 sysctl_runningspace(SYSCTL_HANDLER_ARGS) 339 { 340 long value; 341 int error; 342 343 value = *(long *)arg1; 344 error = sysctl_handle_long(oidp, &value, 0, req); 345 if (error != 0 || req->newptr == NULL) 346 return (error); 347 mtx_lock(&rbreqlock); 348 if (arg1 == &hirunningspace) { 349 if (value < lorunningspace) 350 error = EINVAL; 351 else 352 hirunningspace = value; 353 } else { 354 KASSERT(arg1 == &lorunningspace, 355 ("%s: unknown arg1", __func__)); 356 if (value > hirunningspace) 357 error = EINVAL; 358 else 359 lorunningspace = value; 360 } 361 mtx_unlock(&rbreqlock); 362 return (error); 363 } 364 365 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 366 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 367 static int 368 sysctl_bufspace(SYSCTL_HANDLER_ARGS) 369 { 370 long lvalue; 371 int ivalue; 372 373 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long)) 374 return (sysctl_handle_long(oidp, arg1, arg2, req)); 375 lvalue = *(long *)arg1; 376 if (lvalue > INT_MAX) 377 /* On overflow, still write out a long to trigger ENOMEM. */ 378 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 379 ivalue = lvalue; 380 return (sysctl_handle_int(oidp, &ivalue, 0, req)); 381 } 382 #endif 383 384 /* 385 * bqlock: 386 * 387 * Return the appropriate queue lock based on the index. 388 */ 389 static inline struct mtx * 390 bqlock(int qindex) 391 { 392 393 if (qindex == QUEUE_DIRTY) 394 return (struct mtx *)(&bqdirty); 395 return (struct mtx *)(&bqclean); 396 } 397 398 /* 399 * bdirtywakeup: 400 * 401 * Wakeup any bwillwrite() waiters. 402 */ 403 static void 404 bdirtywakeup(void) 405 { 406 mtx_lock(&bdirtylock); 407 if (bdirtywait) { 408 bdirtywait = 0; 409 wakeup(&bdirtywait); 410 } 411 mtx_unlock(&bdirtylock); 412 } 413 414 /* 415 * bdirtysub: 416 * 417 * Decrement the numdirtybuffers count by one and wakeup any 418 * threads blocked in bwillwrite(). 419 */ 420 static void 421 bdirtysub(void) 422 { 423 424 if (atomic_fetchadd_int(&numdirtybuffers, -1) == 425 (lodirtybuffers + hidirtybuffers) / 2) 426 bdirtywakeup(); 427 } 428 429 /* 430 * bdirtyadd: 431 * 432 * Increment the numdirtybuffers count by one and wakeup the buf 433 * daemon if needed. 434 */ 435 static void 436 bdirtyadd(void) 437 { 438 439 /* 440 * Only do the wakeup once as we cross the boundary. The 441 * buf daemon will keep running until the condition clears. 442 */ 443 if (atomic_fetchadd_int(&numdirtybuffers, 1) == 444 (lodirtybuffers + hidirtybuffers) / 2) 445 bd_wakeup(); 446 } 447 448 /* 449 * bufspacewakeup: 450 * 451 * Called when buffer space is potentially available for recovery. 452 * getnewbuf() will block on this flag when it is unable to free 453 * sufficient buffer space. Buffer space becomes recoverable when 454 * bp's get placed back in the queues. 455 */ 456 static __inline void 457 bufspacewakeup(void) 458 { 459 int need_wakeup, on; 460 461 /* 462 * If someone is waiting for bufspace, wake them up. Even 463 * though we may not have freed the kva space yet, the waiting 464 * process will be able to now. 465 */ 466 rw_rlock(&nblock); 467 for (;;) { 468 need_wakeup = 0; 469 on = needsbuffer; 470 if ((on & VFS_BIO_NEED_BUFSPACE) == 0) 471 break; 472 need_wakeup = 1; 473 if (atomic_cmpset_rel_int(&needsbuffer, on, 474 on & ~VFS_BIO_NEED_BUFSPACE)) 475 break; 476 } 477 if (need_wakeup) 478 wakeup(__DEVOLATILE(void *, &needsbuffer)); 479 rw_runlock(&nblock); 480 } 481 482 /* 483 * bufspaceadjust: 484 * 485 * Adjust the reported bufspace for a KVA managed buffer, possibly 486 * waking any waiters. 487 */ 488 static void 489 bufspaceadjust(struct buf *bp, int bufsize) 490 { 491 int diff; 492 493 KASSERT((bp->b_flags & B_MALLOC) == 0, 494 ("bufspaceadjust: malloc buf %p", bp)); 495 diff = bufsize - bp->b_bufsize; 496 if (diff < 0) { 497 atomic_subtract_long(&bufspace, -diff); 498 bufspacewakeup(); 499 } else 500 atomic_add_long(&bufspace, diff); 501 bp->b_bufsize = bufsize; 502 } 503 504 /* 505 * bufmallocadjust: 506 * 507 * Adjust the reported bufspace for a malloc managed buffer, possibly 508 * waking any waiters. 509 */ 510 static void 511 bufmallocadjust(struct buf *bp, int bufsize) 512 { 513 int diff; 514 515 KASSERT((bp->b_flags & B_MALLOC) != 0, 516 ("bufmallocadjust: non-malloc buf %p", bp)); 517 diff = bufsize - bp->b_bufsize; 518 if (diff < 0) { 519 atomic_subtract_long(&bufmallocspace, -diff); 520 bufspacewakeup(); 521 } else 522 atomic_add_long(&bufmallocspace, diff); 523 bp->b_bufsize = bufsize; 524 } 525 526 /* 527 * runningwakeup: 528 * 529 * Wake up processes that are waiting on asynchronous writes to fall 530 * below lorunningspace. 531 */ 532 static void 533 runningwakeup(void) 534 { 535 536 mtx_lock(&rbreqlock); 537 if (runningbufreq) { 538 runningbufreq = 0; 539 wakeup(&runningbufreq); 540 } 541 mtx_unlock(&rbreqlock); 542 } 543 544 /* 545 * runningbufwakeup: 546 * 547 * Decrement the outstanding write count according. 548 */ 549 void 550 runningbufwakeup(struct buf *bp) 551 { 552 long space, bspace; 553 554 bspace = bp->b_runningbufspace; 555 if (bspace == 0) 556 return; 557 space = atomic_fetchadd_long(&runningbufspace, -bspace); 558 KASSERT(space >= bspace, ("runningbufspace underflow %ld %ld", 559 space, bspace)); 560 bp->b_runningbufspace = 0; 561 /* 562 * Only acquire the lock and wakeup on the transition from exceeding 563 * the threshold to falling below it. 564 */ 565 if (space < lorunningspace) 566 return; 567 if (space - bspace > lorunningspace) 568 return; 569 runningwakeup(); 570 } 571 572 /* 573 * bufcountadd: 574 * 575 * Called when a buffer has been added to one of the free queues to 576 * account for the buffer and to wakeup anyone waiting for free buffers. 577 * This typically occurs when large amounts of metadata are being handled 578 * by the buffer cache ( else buffer space runs out first, usually ). 579 */ 580 static __inline void 581 bufcountadd(struct buf *bp) 582 { 583 int mask, need_wakeup, old, on; 584 585 KASSERT((bp->b_flags & B_INFREECNT) == 0, 586 ("buf %p already counted as free", bp)); 587 bp->b_flags |= B_INFREECNT; 588 old = atomic_fetchadd_int(&numfreebuffers, 1); 589 KASSERT(old >= 0 && old < nbuf, 590 ("numfreebuffers climbed to %d", old + 1)); 591 mask = VFS_BIO_NEED_ANY; 592 if (numfreebuffers >= hifreebuffers) 593 mask |= VFS_BIO_NEED_FREE; 594 rw_rlock(&nblock); 595 for (;;) { 596 need_wakeup = 0; 597 on = needsbuffer; 598 if (on == 0) 599 break; 600 need_wakeup = 1; 601 if (atomic_cmpset_rel_int(&needsbuffer, on, on & ~mask)) 602 break; 603 } 604 if (need_wakeup) 605 wakeup(__DEVOLATILE(void *, &needsbuffer)); 606 rw_runlock(&nblock); 607 } 608 609 /* 610 * bufcountsub: 611 * 612 * Decrement the numfreebuffers count as needed. 613 */ 614 static void 615 bufcountsub(struct buf *bp) 616 { 617 int old; 618 619 /* 620 * Fixup numfreebuffers count. If the buffer is invalid or not 621 * delayed-write, the buffer was free and we must decrement 622 * numfreebuffers. 623 */ 624 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { 625 KASSERT((bp->b_flags & B_INFREECNT) != 0, 626 ("buf %p not counted in numfreebuffers", bp)); 627 bp->b_flags &= ~B_INFREECNT; 628 old = atomic_fetchadd_int(&numfreebuffers, -1); 629 KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1)); 630 } 631 } 632 633 /* 634 * waitrunningbufspace() 635 * 636 * runningbufspace is a measure of the amount of I/O currently 637 * running. This routine is used in async-write situations to 638 * prevent creating huge backups of pending writes to a device. 639 * Only asynchronous writes are governed by this function. 640 * 641 * This does NOT turn an async write into a sync write. It waits 642 * for earlier writes to complete and generally returns before the 643 * caller's write has reached the device. 644 */ 645 void 646 waitrunningbufspace(void) 647 { 648 649 mtx_lock(&rbreqlock); 650 while (runningbufspace > hirunningspace) { 651 runningbufreq = 1; 652 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 653 } 654 mtx_unlock(&rbreqlock); 655 } 656 657 658 /* 659 * vfs_buf_test_cache: 660 * 661 * Called when a buffer is extended. This function clears the B_CACHE 662 * bit if the newly extended portion of the buffer does not contain 663 * valid data. 664 */ 665 static __inline 666 void 667 vfs_buf_test_cache(struct buf *bp, 668 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 669 vm_page_t m) 670 { 671 672 VM_OBJECT_ASSERT_LOCKED(m->object); 673 if (bp->b_flags & B_CACHE) { 674 int base = (foff + off) & PAGE_MASK; 675 if (vm_page_is_valid(m, base, size) == 0) 676 bp->b_flags &= ~B_CACHE; 677 } 678 } 679 680 /* Wake up the buffer daemon if necessary */ 681 static __inline void 682 bd_wakeup(void) 683 { 684 685 mtx_lock(&bdlock); 686 if (bd_request == 0) { 687 bd_request = 1; 688 wakeup(&bd_request); 689 } 690 mtx_unlock(&bdlock); 691 } 692 693 /* 694 * bd_speedup - speedup the buffer cache flushing code 695 */ 696 void 697 bd_speedup(void) 698 { 699 int needwake; 700 701 mtx_lock(&bdlock); 702 needwake = 0; 703 if (bd_speedupreq == 0 || bd_request == 0) 704 needwake = 1; 705 bd_speedupreq = 1; 706 bd_request = 1; 707 if (needwake) 708 wakeup(&bd_request); 709 mtx_unlock(&bdlock); 710 } 711 712 #ifndef NSWBUF_MIN 713 #define NSWBUF_MIN 16 714 #endif 715 716 #ifdef __i386__ 717 #define TRANSIENT_DENOM 5 718 #else 719 #define TRANSIENT_DENOM 10 720 #endif 721 722 /* 723 * Calculating buffer cache scaling values and reserve space for buffer 724 * headers. This is called during low level kernel initialization and 725 * may be called more then once. We CANNOT write to the memory area 726 * being reserved at this time. 727 */ 728 caddr_t 729 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 730 { 731 int tuned_nbuf; 732 long maxbuf, maxbuf_sz, buf_sz, biotmap_sz; 733 734 /* 735 * physmem_est is in pages. Convert it to kilobytes (assumes 736 * PAGE_SIZE is >= 1K) 737 */ 738 physmem_est = physmem_est * (PAGE_SIZE / 1024); 739 740 /* 741 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 742 * For the first 64MB of ram nominally allocate sufficient buffers to 743 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 744 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing 745 * the buffer cache we limit the eventual kva reservation to 746 * maxbcache bytes. 747 * 748 * factor represents the 1/4 x ram conversion. 749 */ 750 if (nbuf == 0) { 751 int factor = 4 * BKVASIZE / 1024; 752 753 nbuf = 50; 754 if (physmem_est > 4096) 755 nbuf += min((physmem_est - 4096) / factor, 756 65536 / factor); 757 if (physmem_est > 65536) 758 nbuf += min((physmem_est - 65536) * 2 / (factor * 5), 759 32 * 1024 * 1024 / (factor * 5)); 760 761 if (maxbcache && nbuf > maxbcache / BKVASIZE) 762 nbuf = maxbcache / BKVASIZE; 763 tuned_nbuf = 1; 764 } else 765 tuned_nbuf = 0; 766 767 /* XXX Avoid unsigned long overflows later on with maxbufspace. */ 768 maxbuf = (LONG_MAX / 3) / BKVASIZE; 769 if (nbuf > maxbuf) { 770 if (!tuned_nbuf) 771 printf("Warning: nbufs lowered from %d to %ld\n", nbuf, 772 maxbuf); 773 nbuf = maxbuf; 774 } 775 776 /* 777 * Ideal allocation size for the transient bio submap is 10% 778 * of the maximal space buffer map. This roughly corresponds 779 * to the amount of the buffer mapped for typical UFS load. 780 * 781 * Clip the buffer map to reserve space for the transient 782 * BIOs, if its extent is bigger than 90% (80% on i386) of the 783 * maximum buffer map extent on the platform. 784 * 785 * The fall-back to the maxbuf in case of maxbcache unset, 786 * allows to not trim the buffer KVA for the architectures 787 * with ample KVA space. 788 */ 789 if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) { 790 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE; 791 buf_sz = (long)nbuf * BKVASIZE; 792 if (buf_sz < maxbuf_sz / TRANSIENT_DENOM * 793 (TRANSIENT_DENOM - 1)) { 794 /* 795 * There is more KVA than memory. Do not 796 * adjust buffer map size, and assign the rest 797 * of maxbuf to transient map. 798 */ 799 biotmap_sz = maxbuf_sz - buf_sz; 800 } else { 801 /* 802 * Buffer map spans all KVA we could afford on 803 * this platform. Give 10% (20% on i386) of 804 * the buffer map to the transient bio map. 805 */ 806 biotmap_sz = buf_sz / TRANSIENT_DENOM; 807 buf_sz -= biotmap_sz; 808 } 809 if (biotmap_sz / INT_MAX > MAXPHYS) 810 bio_transient_maxcnt = INT_MAX; 811 else 812 bio_transient_maxcnt = biotmap_sz / MAXPHYS; 813 /* 814 * Artifically limit to 1024 simultaneous in-flight I/Os 815 * using the transient mapping. 816 */ 817 if (bio_transient_maxcnt > 1024) 818 bio_transient_maxcnt = 1024; 819 if (tuned_nbuf) 820 nbuf = buf_sz / BKVASIZE; 821 } 822 823 /* 824 * swbufs are used as temporary holders for I/O, such as paging I/O. 825 * We have no less then 16 and no more then 256. 826 */ 827 nswbuf = min(nbuf / 4, 256); 828 TUNABLE_INT_FETCH("kern.nswbuf", &nswbuf); 829 if (nswbuf < NSWBUF_MIN) 830 nswbuf = NSWBUF_MIN; 831 832 /* 833 * Reserve space for the buffer cache buffers 834 */ 835 swbuf = (void *)v; 836 v = (caddr_t)(swbuf + nswbuf); 837 buf = (void *)v; 838 v = (caddr_t)(buf + nbuf); 839 840 return(v); 841 } 842 843 /* Initialize the buffer subsystem. Called before use of any buffers. */ 844 void 845 bufinit(void) 846 { 847 struct buf *bp; 848 int i; 849 850 CTASSERT(MAXBCACHEBUF >= MAXBSIZE); 851 mtx_init(&bqclean, "bufq clean lock", NULL, MTX_DEF); 852 mtx_init(&bqdirty, "bufq dirty lock", NULL, MTX_DEF); 853 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 854 rw_init(&nblock, "needsbuffer lock"); 855 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 856 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF); 857 858 /* next, make a null set of free lists */ 859 for (i = 0; i < BUFFER_QUEUES; i++) 860 TAILQ_INIT(&bufqueues[i]); 861 862 unmapped_buf = (caddr_t)kva_alloc(MAXPHYS); 863 864 /* finally, initialize each buffer header and stick on empty q */ 865 for (i = 0; i < nbuf; i++) { 866 bp = &buf[i]; 867 bzero(bp, sizeof *bp); 868 bp->b_flags = B_INVAL | B_INFREECNT; 869 bp->b_rcred = NOCRED; 870 bp->b_wcred = NOCRED; 871 bp->b_qindex = QUEUE_EMPTY; 872 bp->b_xflags = 0; 873 bp->b_data = bp->b_kvabase = unmapped_buf; 874 LIST_INIT(&bp->b_dep); 875 BUF_LOCKINIT(bp); 876 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 877 #ifdef INVARIANTS 878 bq_len[QUEUE_EMPTY]++; 879 #endif 880 } 881 882 /* 883 * maxbufspace is the absolute maximum amount of buffer space we are 884 * allowed to reserve in KVM and in real terms. The absolute maximum 885 * is nominally used by buf_daemon. hibufspace is the nominal maximum 886 * used by most other processes. The differential is required to 887 * ensure that buf_daemon is able to run when other processes might 888 * be blocked waiting for buffer space. 889 * 890 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 891 * this may result in KVM fragmentation which is not handled optimally 892 * by the system. 893 */ 894 maxbufspace = (long)nbuf * BKVASIZE; 895 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - MAXBCACHEBUF * 10); 896 lobufspace = hibufspace - MAXBCACHEBUF; 897 898 /* 899 * Note: The 16 MiB upper limit for hirunningspace was chosen 900 * arbitrarily and may need further tuning. It corresponds to 901 * 128 outstanding write IO requests (if IO size is 128 KiB), 902 * which fits with many RAID controllers' tagged queuing limits. 903 * The lower 1 MiB limit is the historical upper limit for 904 * hirunningspace. 905 */ 906 hirunningspace = lmax(lmin(roundup(hibufspace / 64, MAXBCACHEBUF), 907 16 * 1024 * 1024), 1024 * 1024); 908 lorunningspace = roundup((hirunningspace * 2) / 3, MAXBCACHEBUF); 909 910 /* 911 * Limit the amount of malloc memory since it is wired permanently into 912 * the kernel space. Even though this is accounted for in the buffer 913 * allocation, we don't want the malloced region to grow uncontrolled. 914 * The malloc scheme improves memory utilization significantly on average 915 * (small) directories. 916 */ 917 maxbufmallocspace = hibufspace / 20; 918 919 /* 920 * Reduce the chance of a deadlock occuring by limiting the number 921 * of delayed-write dirty buffers we allow to stack up. 922 */ 923 hidirtybuffers = nbuf / 4 + 20; 924 dirtybufthresh = hidirtybuffers * 9 / 10; 925 numdirtybuffers = 0; 926 /* 927 * To support extreme low-memory systems, make sure hidirtybuffers cannot 928 * eat up all available buffer space. This occurs when our minimum cannot 929 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 930 * BKVASIZE'd buffers. 931 */ 932 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 933 hidirtybuffers >>= 1; 934 } 935 lodirtybuffers = hidirtybuffers / 2; 936 937 /* 938 * Try to keep the number of free buffers in the specified range, 939 * and give special processes (e.g. like buf_daemon) access to an 940 * emergency reserve. 941 */ 942 lofreebuffers = nbuf / 18 + 5; 943 hifreebuffers = 2 * lofreebuffers; 944 numfreebuffers = nbuf; 945 946 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ | 947 VM_ALLOC_NORMAL | VM_ALLOC_WIRED); 948 } 949 950 #ifdef INVARIANTS 951 static inline void 952 vfs_buf_check_mapped(struct buf *bp) 953 { 954 955 KASSERT(bp->b_kvabase != unmapped_buf, 956 ("mapped buf: b_kvabase was not updated %p", bp)); 957 KASSERT(bp->b_data != unmapped_buf, 958 ("mapped buf: b_data was not updated %p", bp)); 959 KASSERT(bp->b_data < unmapped_buf || bp->b_data > unmapped_buf + 960 MAXPHYS, ("b_data + b_offset unmapped %p", bp)); 961 } 962 963 static inline void 964 vfs_buf_check_unmapped(struct buf *bp) 965 { 966 967 KASSERT(bp->b_data == unmapped_buf, 968 ("unmapped buf: corrupted b_data %p", bp)); 969 } 970 971 #define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp) 972 #define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp) 973 #else 974 #define BUF_CHECK_MAPPED(bp) do {} while (0) 975 #define BUF_CHECK_UNMAPPED(bp) do {} while (0) 976 #endif 977 978 static void 979 bpmap_qenter(struct buf *bp) 980 { 981 982 BUF_CHECK_MAPPED(bp); 983 984 /* 985 * bp->b_data is relative to bp->b_offset, but 986 * bp->b_offset may be offset into the first page. 987 */ 988 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data); 989 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages); 990 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 991 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 992 } 993 994 /* 995 * binsfree: 996 * 997 * Insert the buffer into the appropriate free list. 998 */ 999 static void 1000 binsfree(struct buf *bp, int qindex) 1001 { 1002 struct mtx *olock, *nlock; 1003 1004 BUF_ASSERT_XLOCKED(bp); 1005 1006 nlock = bqlock(qindex); 1007 /* Handle delayed bremfree() processing. */ 1008 if (bp->b_flags & B_REMFREE) { 1009 olock = bqlock(bp->b_qindex); 1010 mtx_lock(olock); 1011 bremfreel(bp); 1012 if (olock != nlock) { 1013 mtx_unlock(olock); 1014 mtx_lock(nlock); 1015 } 1016 } else 1017 mtx_lock(nlock); 1018 1019 if (bp->b_qindex != QUEUE_NONE) 1020 panic("binsfree: free buffer onto another queue???"); 1021 1022 bp->b_qindex = qindex; 1023 if (bp->b_flags & B_AGE) 1024 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1025 else 1026 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1027 #ifdef INVARIANTS 1028 bq_len[bp->b_qindex]++; 1029 #endif 1030 mtx_unlock(nlock); 1031 1032 /* 1033 * Something we can maybe free or reuse. 1034 */ 1035 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1036 bufspacewakeup(); 1037 1038 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI)) 1039 bufcountadd(bp); 1040 } 1041 1042 /* 1043 * bremfree: 1044 * 1045 * Mark the buffer for removal from the appropriate free list. 1046 * 1047 */ 1048 void 1049 bremfree(struct buf *bp) 1050 { 1051 1052 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1053 KASSERT((bp->b_flags & B_REMFREE) == 0, 1054 ("bremfree: buffer %p already marked for delayed removal.", bp)); 1055 KASSERT(bp->b_qindex != QUEUE_NONE, 1056 ("bremfree: buffer %p not on a queue.", bp)); 1057 BUF_ASSERT_XLOCKED(bp); 1058 1059 bp->b_flags |= B_REMFREE; 1060 bufcountsub(bp); 1061 } 1062 1063 /* 1064 * bremfreef: 1065 * 1066 * Force an immediate removal from a free list. Used only in nfs when 1067 * it abuses the b_freelist pointer. 1068 */ 1069 void 1070 bremfreef(struct buf *bp) 1071 { 1072 struct mtx *qlock; 1073 1074 qlock = bqlock(bp->b_qindex); 1075 mtx_lock(qlock); 1076 bremfreel(bp); 1077 mtx_unlock(qlock); 1078 } 1079 1080 /* 1081 * bremfreel: 1082 * 1083 * Removes a buffer from the free list, must be called with the 1084 * correct qlock held. 1085 */ 1086 static void 1087 bremfreel(struct buf *bp) 1088 { 1089 1090 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X", 1091 bp, bp->b_vp, bp->b_flags); 1092 KASSERT(bp->b_qindex != QUEUE_NONE, 1093 ("bremfreel: buffer %p not on a queue.", bp)); 1094 BUF_ASSERT_XLOCKED(bp); 1095 mtx_assert(bqlock(bp->b_qindex), MA_OWNED); 1096 1097 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 1098 #ifdef INVARIANTS 1099 KASSERT(bq_len[bp->b_qindex] >= 1, ("queue %d underflow", 1100 bp->b_qindex)); 1101 bq_len[bp->b_qindex]--; 1102 #endif 1103 bp->b_qindex = QUEUE_NONE; 1104 /* 1105 * If this was a delayed bremfree() we only need to remove the buffer 1106 * from the queue and return the stats are already done. 1107 */ 1108 if (bp->b_flags & B_REMFREE) { 1109 bp->b_flags &= ~B_REMFREE; 1110 return; 1111 } 1112 bufcountsub(bp); 1113 } 1114 1115 /* 1116 * bufkvafree: 1117 * 1118 * Free the kva allocation for a buffer. 1119 * 1120 */ 1121 static void 1122 bufkvafree(struct buf *bp) 1123 { 1124 1125 #ifdef INVARIANTS 1126 if (bp->b_kvasize == 0) { 1127 KASSERT(bp->b_kvabase == unmapped_buf && 1128 bp->b_data == unmapped_buf, 1129 ("Leaked KVA space on %p", bp)); 1130 } else if (buf_mapped(bp)) 1131 BUF_CHECK_MAPPED(bp); 1132 else 1133 BUF_CHECK_UNMAPPED(bp); 1134 #endif 1135 if (bp->b_kvasize == 0) 1136 return; 1137 1138 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, bp->b_kvasize); 1139 atomic_subtract_long(&bufkvaspace, bp->b_kvasize); 1140 atomic_add_int(&buffreekvacnt, 1); 1141 bp->b_data = bp->b_kvabase = unmapped_buf; 1142 bp->b_kvasize = 0; 1143 } 1144 1145 /* 1146 * bufkvaalloc: 1147 * 1148 * Allocate the buffer KVA and set b_kvasize and b_kvabase. 1149 */ 1150 static int 1151 bufkvaalloc(struct buf *bp, int maxsize, int gbflags) 1152 { 1153 vm_offset_t addr; 1154 int error; 1155 1156 KASSERT((gbflags & GB_UNMAPPED) == 0 || (gbflags & GB_KVAALLOC) != 0, 1157 ("Invalid gbflags 0x%x in %s", gbflags, __func__)); 1158 1159 bufkvafree(bp); 1160 1161 addr = 0; 1162 error = vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr); 1163 if (error != 0) { 1164 /* 1165 * Buffer map is too fragmented. Request the caller 1166 * to defragment the map. 1167 */ 1168 atomic_add_int(&bufdefragcnt, 1); 1169 return (error); 1170 } 1171 bp->b_kvabase = (caddr_t)addr; 1172 bp->b_kvasize = maxsize; 1173 atomic_add_long(&bufkvaspace, bp->b_kvasize); 1174 if ((gbflags & GB_UNMAPPED) != 0) { 1175 bp->b_data = unmapped_buf; 1176 BUF_CHECK_UNMAPPED(bp); 1177 } else { 1178 bp->b_data = bp->b_kvabase; 1179 BUF_CHECK_MAPPED(bp); 1180 } 1181 return (0); 1182 } 1183 1184 /* 1185 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 1186 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 1187 * the buffer is valid and we do not have to do anything. 1188 */ 1189 void 1190 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, 1191 int cnt, struct ucred * cred) 1192 { 1193 struct buf *rabp; 1194 int i; 1195 1196 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 1197 if (inmem(vp, *rablkno)) 1198 continue; 1199 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 1200 1201 if ((rabp->b_flags & B_CACHE) == 0) { 1202 if (!TD_IS_IDLETHREAD(curthread)) 1203 curthread->td_ru.ru_inblock++; 1204 rabp->b_flags |= B_ASYNC; 1205 rabp->b_flags &= ~B_INVAL; 1206 rabp->b_ioflags &= ~BIO_ERROR; 1207 rabp->b_iocmd = BIO_READ; 1208 if (rabp->b_rcred == NOCRED && cred != NOCRED) 1209 rabp->b_rcred = crhold(cred); 1210 vfs_busy_pages(rabp, 0); 1211 BUF_KERNPROC(rabp); 1212 rabp->b_iooffset = dbtob(rabp->b_blkno); 1213 bstrategy(rabp); 1214 } else { 1215 brelse(rabp); 1216 } 1217 } 1218 } 1219 1220 /* 1221 * Entry point for bread() and breadn() via #defines in sys/buf.h. 1222 * 1223 * Get a buffer with the specified data. Look in the cache first. We 1224 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 1225 * is set, the buffer is valid and we do not have to do anything, see 1226 * getblk(). Also starts asynchronous I/O on read-ahead blocks. 1227 */ 1228 int 1229 breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno, 1230 int *rabsize, int cnt, struct ucred *cred, int flags, struct buf **bpp) 1231 { 1232 struct buf *bp; 1233 int rv = 0, readwait = 0; 1234 1235 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 1236 /* 1237 * Can only return NULL if GB_LOCK_NOWAIT flag is specified. 1238 */ 1239 *bpp = bp = getblk(vp, blkno, size, 0, 0, flags); 1240 if (bp == NULL) 1241 return (EBUSY); 1242 1243 /* if not found in cache, do some I/O */ 1244 if ((bp->b_flags & B_CACHE) == 0) { 1245 if (!TD_IS_IDLETHREAD(curthread)) 1246 curthread->td_ru.ru_inblock++; 1247 bp->b_iocmd = BIO_READ; 1248 bp->b_flags &= ~B_INVAL; 1249 bp->b_ioflags &= ~BIO_ERROR; 1250 if (bp->b_rcred == NOCRED && cred != NOCRED) 1251 bp->b_rcred = crhold(cred); 1252 vfs_busy_pages(bp, 0); 1253 bp->b_iooffset = dbtob(bp->b_blkno); 1254 bstrategy(bp); 1255 ++readwait; 1256 } 1257 1258 breada(vp, rablkno, rabsize, cnt, cred); 1259 1260 if (readwait) { 1261 rv = bufwait(bp); 1262 } 1263 return (rv); 1264 } 1265 1266 /* 1267 * Write, release buffer on completion. (Done by iodone 1268 * if async). Do not bother writing anything if the buffer 1269 * is invalid. 1270 * 1271 * Note that we set B_CACHE here, indicating that buffer is 1272 * fully valid and thus cacheable. This is true even of NFS 1273 * now so we set it generally. This could be set either here 1274 * or in biodone() since the I/O is synchronous. We put it 1275 * here. 1276 */ 1277 int 1278 bufwrite(struct buf *bp) 1279 { 1280 int oldflags; 1281 struct vnode *vp; 1282 long space; 1283 int vp_md; 1284 1285 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1286 if ((bp->b_bufobj->bo_flag & BO_DEAD) != 0) { 1287 bp->b_flags |= B_INVAL | B_RELBUF; 1288 bp->b_flags &= ~B_CACHE; 1289 brelse(bp); 1290 return (ENXIO); 1291 } 1292 if (bp->b_flags & B_INVAL) { 1293 brelse(bp); 1294 return (0); 1295 } 1296 1297 if (bp->b_flags & B_BARRIER) 1298 barrierwrites++; 1299 1300 oldflags = bp->b_flags; 1301 1302 BUF_ASSERT_HELD(bp); 1303 1304 if (bp->b_pin_count > 0) 1305 bunpin_wait(bp); 1306 1307 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 1308 ("FFS background buffer should not get here %p", bp)); 1309 1310 vp = bp->b_vp; 1311 if (vp) 1312 vp_md = vp->v_vflag & VV_MD; 1313 else 1314 vp_md = 0; 1315 1316 /* 1317 * Mark the buffer clean. Increment the bufobj write count 1318 * before bundirty() call, to prevent other thread from seeing 1319 * empty dirty list and zero counter for writes in progress, 1320 * falsely indicating that the bufobj is clean. 1321 */ 1322 bufobj_wref(bp->b_bufobj); 1323 bundirty(bp); 1324 1325 bp->b_flags &= ~B_DONE; 1326 bp->b_ioflags &= ~BIO_ERROR; 1327 bp->b_flags |= B_CACHE; 1328 bp->b_iocmd = BIO_WRITE; 1329 1330 vfs_busy_pages(bp, 1); 1331 1332 /* 1333 * Normal bwrites pipeline writes 1334 */ 1335 bp->b_runningbufspace = bp->b_bufsize; 1336 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace); 1337 1338 if (!TD_IS_IDLETHREAD(curthread)) 1339 curthread->td_ru.ru_oublock++; 1340 if (oldflags & B_ASYNC) 1341 BUF_KERNPROC(bp); 1342 bp->b_iooffset = dbtob(bp->b_blkno); 1343 bstrategy(bp); 1344 1345 if ((oldflags & B_ASYNC) == 0) { 1346 int rtval = bufwait(bp); 1347 brelse(bp); 1348 return (rtval); 1349 } else if (space > hirunningspace) { 1350 /* 1351 * don't allow the async write to saturate the I/O 1352 * system. We will not deadlock here because 1353 * we are blocking waiting for I/O that is already in-progress 1354 * to complete. We do not block here if it is the update 1355 * or syncer daemon trying to clean up as that can lead 1356 * to deadlock. 1357 */ 1358 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 1359 waitrunningbufspace(); 1360 } 1361 1362 return (0); 1363 } 1364 1365 void 1366 bufbdflush(struct bufobj *bo, struct buf *bp) 1367 { 1368 struct buf *nbp; 1369 1370 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 1371 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 1372 altbufferflushes++; 1373 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 1374 BO_LOCK(bo); 1375 /* 1376 * Try to find a buffer to flush. 1377 */ 1378 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 1379 if ((nbp->b_vflags & BV_BKGRDINPROG) || 1380 BUF_LOCK(nbp, 1381 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 1382 continue; 1383 if (bp == nbp) 1384 panic("bdwrite: found ourselves"); 1385 BO_UNLOCK(bo); 1386 /* Don't countdeps with the bo lock held. */ 1387 if (buf_countdeps(nbp, 0)) { 1388 BO_LOCK(bo); 1389 BUF_UNLOCK(nbp); 1390 continue; 1391 } 1392 if (nbp->b_flags & B_CLUSTEROK) { 1393 vfs_bio_awrite(nbp); 1394 } else { 1395 bremfree(nbp); 1396 bawrite(nbp); 1397 } 1398 dirtybufferflushes++; 1399 break; 1400 } 1401 if (nbp == NULL) 1402 BO_UNLOCK(bo); 1403 } 1404 } 1405 1406 /* 1407 * Delayed write. (Buffer is marked dirty). Do not bother writing 1408 * anything if the buffer is marked invalid. 1409 * 1410 * Note that since the buffer must be completely valid, we can safely 1411 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 1412 * biodone() in order to prevent getblk from writing the buffer 1413 * out synchronously. 1414 */ 1415 void 1416 bdwrite(struct buf *bp) 1417 { 1418 struct thread *td = curthread; 1419 struct vnode *vp; 1420 struct bufobj *bo; 1421 1422 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1423 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1424 KASSERT((bp->b_flags & B_BARRIER) == 0, 1425 ("Barrier request in delayed write %p", bp)); 1426 BUF_ASSERT_HELD(bp); 1427 1428 if (bp->b_flags & B_INVAL) { 1429 brelse(bp); 1430 return; 1431 } 1432 1433 /* 1434 * If we have too many dirty buffers, don't create any more. 1435 * If we are wildly over our limit, then force a complete 1436 * cleanup. Otherwise, just keep the situation from getting 1437 * out of control. Note that we have to avoid a recursive 1438 * disaster and not try to clean up after our own cleanup! 1439 */ 1440 vp = bp->b_vp; 1441 bo = bp->b_bufobj; 1442 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 1443 td->td_pflags |= TDP_INBDFLUSH; 1444 BO_BDFLUSH(bo, bp); 1445 td->td_pflags &= ~TDP_INBDFLUSH; 1446 } else 1447 recursiveflushes++; 1448 1449 bdirty(bp); 1450 /* 1451 * Set B_CACHE, indicating that the buffer is fully valid. This is 1452 * true even of NFS now. 1453 */ 1454 bp->b_flags |= B_CACHE; 1455 1456 /* 1457 * This bmap keeps the system from needing to do the bmap later, 1458 * perhaps when the system is attempting to do a sync. Since it 1459 * is likely that the indirect block -- or whatever other datastructure 1460 * that the filesystem needs is still in memory now, it is a good 1461 * thing to do this. Note also, that if the pageout daemon is 1462 * requesting a sync -- there might not be enough memory to do 1463 * the bmap then... So, this is important to do. 1464 */ 1465 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 1466 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 1467 } 1468 1469 /* 1470 * Set the *dirty* buffer range based upon the VM system dirty 1471 * pages. 1472 * 1473 * Mark the buffer pages as clean. We need to do this here to 1474 * satisfy the vnode_pager and the pageout daemon, so that it 1475 * thinks that the pages have been "cleaned". Note that since 1476 * the pages are in a delayed write buffer -- the VFS layer 1477 * "will" see that the pages get written out on the next sync, 1478 * or perhaps the cluster will be completed. 1479 */ 1480 vfs_clean_pages_dirty_buf(bp); 1481 bqrelse(bp); 1482 1483 /* 1484 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 1485 * due to the softdep code. 1486 */ 1487 } 1488 1489 /* 1490 * bdirty: 1491 * 1492 * Turn buffer into delayed write request. We must clear BIO_READ and 1493 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 1494 * itself to properly update it in the dirty/clean lists. We mark it 1495 * B_DONE to ensure that any asynchronization of the buffer properly 1496 * clears B_DONE ( else a panic will occur later ). 1497 * 1498 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 1499 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 1500 * should only be called if the buffer is known-good. 1501 * 1502 * Since the buffer is not on a queue, we do not update the numfreebuffers 1503 * count. 1504 * 1505 * The buffer must be on QUEUE_NONE. 1506 */ 1507 void 1508 bdirty(struct buf *bp) 1509 { 1510 1511 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 1512 bp, bp->b_vp, bp->b_flags); 1513 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1514 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1515 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1516 BUF_ASSERT_HELD(bp); 1517 bp->b_flags &= ~(B_RELBUF); 1518 bp->b_iocmd = BIO_WRITE; 1519 1520 if ((bp->b_flags & B_DELWRI) == 0) { 1521 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 1522 reassignbuf(bp); 1523 bdirtyadd(); 1524 } 1525 } 1526 1527 /* 1528 * bundirty: 1529 * 1530 * Clear B_DELWRI for buffer. 1531 * 1532 * Since the buffer is not on a queue, we do not update the numfreebuffers 1533 * count. 1534 * 1535 * The buffer must be on QUEUE_NONE. 1536 */ 1537 1538 void 1539 bundirty(struct buf *bp) 1540 { 1541 1542 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1543 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1544 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1545 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1546 BUF_ASSERT_HELD(bp); 1547 1548 if (bp->b_flags & B_DELWRI) { 1549 bp->b_flags &= ~B_DELWRI; 1550 reassignbuf(bp); 1551 bdirtysub(); 1552 } 1553 /* 1554 * Since it is now being written, we can clear its deferred write flag. 1555 */ 1556 bp->b_flags &= ~B_DEFERRED; 1557 } 1558 1559 /* 1560 * bawrite: 1561 * 1562 * Asynchronous write. Start output on a buffer, but do not wait for 1563 * it to complete. The buffer is released when the output completes. 1564 * 1565 * bwrite() ( or the VOP routine anyway ) is responsible for handling 1566 * B_INVAL buffers. Not us. 1567 */ 1568 void 1569 bawrite(struct buf *bp) 1570 { 1571 1572 bp->b_flags |= B_ASYNC; 1573 (void) bwrite(bp); 1574 } 1575 1576 /* 1577 * babarrierwrite: 1578 * 1579 * Asynchronous barrier write. Start output on a buffer, but do not 1580 * wait for it to complete. Place a write barrier after this write so 1581 * that this buffer and all buffers written before it are committed to 1582 * the disk before any buffers written after this write are committed 1583 * to the disk. The buffer is released when the output completes. 1584 */ 1585 void 1586 babarrierwrite(struct buf *bp) 1587 { 1588 1589 bp->b_flags |= B_ASYNC | B_BARRIER; 1590 (void) bwrite(bp); 1591 } 1592 1593 /* 1594 * bbarrierwrite: 1595 * 1596 * Synchronous barrier write. Start output on a buffer and wait for 1597 * it to complete. Place a write barrier after this write so that 1598 * this buffer and all buffers written before it are committed to 1599 * the disk before any buffers written after this write are committed 1600 * to the disk. The buffer is released when the output completes. 1601 */ 1602 int 1603 bbarrierwrite(struct buf *bp) 1604 { 1605 1606 bp->b_flags |= B_BARRIER; 1607 return (bwrite(bp)); 1608 } 1609 1610 /* 1611 * bwillwrite: 1612 * 1613 * Called prior to the locking of any vnodes when we are expecting to 1614 * write. We do not want to starve the buffer cache with too many 1615 * dirty buffers so we block here. By blocking prior to the locking 1616 * of any vnodes we attempt to avoid the situation where a locked vnode 1617 * prevents the various system daemons from flushing related buffers. 1618 */ 1619 void 1620 bwillwrite(void) 1621 { 1622 1623 if (numdirtybuffers >= hidirtybuffers) { 1624 mtx_lock(&bdirtylock); 1625 while (numdirtybuffers >= hidirtybuffers) { 1626 bdirtywait = 1; 1627 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4), 1628 "flswai", 0); 1629 } 1630 mtx_unlock(&bdirtylock); 1631 } 1632 } 1633 1634 /* 1635 * Return true if we have too many dirty buffers. 1636 */ 1637 int 1638 buf_dirty_count_severe(void) 1639 { 1640 1641 return(numdirtybuffers >= hidirtybuffers); 1642 } 1643 1644 /* 1645 * brelse: 1646 * 1647 * Release a busy buffer and, if requested, free its resources. The 1648 * buffer will be stashed in the appropriate bufqueue[] allowing it 1649 * to be accessed later as a cache entity or reused for other purposes. 1650 */ 1651 void 1652 brelse(struct buf *bp) 1653 { 1654 int qindex; 1655 1656 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 1657 bp, bp->b_vp, bp->b_flags); 1658 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1659 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1660 1661 if (BUF_LOCKRECURSED(bp)) { 1662 /* 1663 * Do not process, in particular, do not handle the 1664 * B_INVAL/B_RELBUF and do not release to free list. 1665 */ 1666 BUF_UNLOCK(bp); 1667 return; 1668 } 1669 1670 if (bp->b_flags & B_MANAGED) { 1671 bqrelse(bp); 1672 return; 1673 } 1674 1675 if ((bp->b_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) { 1676 BO_LOCK(bp->b_bufobj); 1677 bp->b_vflags &= ~BV_BKGRDERR; 1678 BO_UNLOCK(bp->b_bufobj); 1679 bdirty(bp); 1680 } 1681 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 1682 bp->b_error == EIO && !(bp->b_flags & B_INVAL)) { 1683 /* 1684 * Failed write, redirty. Must clear BIO_ERROR to prevent 1685 * pages from being scrapped. If the error is anything 1686 * other than an I/O error (EIO), assume that retrying 1687 * is futile. 1688 */ 1689 bp->b_ioflags &= ~BIO_ERROR; 1690 bdirty(bp); 1691 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 1692 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 1693 /* 1694 * Either a failed I/O or we were asked to free or not 1695 * cache the buffer. 1696 */ 1697 bp->b_flags |= B_INVAL; 1698 if (!LIST_EMPTY(&bp->b_dep)) 1699 buf_deallocate(bp); 1700 if (bp->b_flags & B_DELWRI) 1701 bdirtysub(); 1702 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1703 if ((bp->b_flags & B_VMIO) == 0) { 1704 if (bp->b_bufsize) 1705 allocbuf(bp, 0); 1706 if (bp->b_vp) 1707 brelvp(bp); 1708 } 1709 } 1710 1711 /* 1712 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1713 * is called with B_DELWRI set, the underlying pages may wind up 1714 * getting freed causing a previous write (bdwrite()) to get 'lost' 1715 * because pages associated with a B_DELWRI bp are marked clean. 1716 * 1717 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1718 * if B_DELWRI is set. 1719 */ 1720 if (bp->b_flags & B_DELWRI) 1721 bp->b_flags &= ~B_RELBUF; 1722 1723 /* 1724 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1725 * constituted, not even NFS buffers now. Two flags effect this. If 1726 * B_INVAL, the struct buf is invalidated but the VM object is kept 1727 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1728 * 1729 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 1730 * invalidated. BIO_ERROR cannot be set for a failed write unless the 1731 * buffer is also B_INVAL because it hits the re-dirtying code above. 1732 * 1733 * Normally we can do this whether a buffer is B_DELWRI or not. If 1734 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1735 * the commit state and we cannot afford to lose the buffer. If the 1736 * buffer has a background write in progress, we need to keep it 1737 * around to prevent it from being reconstituted and starting a second 1738 * background write. 1739 */ 1740 if ((bp->b_flags & B_VMIO) 1741 && !(bp->b_vp->v_mount != NULL && 1742 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 1743 !vn_isdisk(bp->b_vp, NULL) && 1744 (bp->b_flags & B_DELWRI)) 1745 ) { 1746 1747 int i, j, resid; 1748 vm_page_t m; 1749 off_t foff; 1750 vm_pindex_t poff; 1751 vm_object_t obj; 1752 1753 obj = bp->b_bufobj->bo_object; 1754 1755 /* 1756 * Get the base offset and length of the buffer. Note that 1757 * in the VMIO case if the buffer block size is not 1758 * page-aligned then b_data pointer may not be page-aligned. 1759 * But our b_pages[] array *IS* page aligned. 1760 * 1761 * block sizes less then DEV_BSIZE (usually 512) are not 1762 * supported due to the page granularity bits (m->valid, 1763 * m->dirty, etc...). 1764 * 1765 * See man buf(9) for more information 1766 */ 1767 resid = bp->b_bufsize; 1768 foff = bp->b_offset; 1769 for (i = 0; i < bp->b_npages; i++) { 1770 int had_bogus = 0; 1771 1772 m = bp->b_pages[i]; 1773 1774 /* 1775 * If we hit a bogus page, fixup *all* the bogus pages 1776 * now. 1777 */ 1778 if (m == bogus_page) { 1779 poff = OFF_TO_IDX(bp->b_offset); 1780 had_bogus = 1; 1781 1782 VM_OBJECT_RLOCK(obj); 1783 for (j = i; j < bp->b_npages; j++) { 1784 vm_page_t mtmp; 1785 mtmp = bp->b_pages[j]; 1786 if (mtmp == bogus_page) { 1787 mtmp = vm_page_lookup(obj, poff + j); 1788 if (!mtmp) { 1789 panic("brelse: page missing\n"); 1790 } 1791 bp->b_pages[j] = mtmp; 1792 } 1793 } 1794 VM_OBJECT_RUNLOCK(obj); 1795 1796 if ((bp->b_flags & B_INVAL) == 0 && 1797 buf_mapped(bp)) { 1798 BUF_CHECK_MAPPED(bp); 1799 pmap_qenter( 1800 trunc_page((vm_offset_t)bp->b_data), 1801 bp->b_pages, bp->b_npages); 1802 } 1803 m = bp->b_pages[i]; 1804 } 1805 if ((bp->b_flags & B_NOCACHE) || 1806 (bp->b_ioflags & BIO_ERROR && 1807 bp->b_iocmd == BIO_READ)) { 1808 int poffset = foff & PAGE_MASK; 1809 int presid = resid > (PAGE_SIZE - poffset) ? 1810 (PAGE_SIZE - poffset) : resid; 1811 1812 KASSERT(presid >= 0, ("brelse: extra page")); 1813 VM_OBJECT_WLOCK(obj); 1814 while (vm_page_xbusied(m)) { 1815 vm_page_lock(m); 1816 VM_OBJECT_WUNLOCK(obj); 1817 vm_page_busy_sleep(m, "mbncsh"); 1818 VM_OBJECT_WLOCK(obj); 1819 } 1820 if (pmap_page_wired_mappings(m) == 0) 1821 vm_page_set_invalid(m, poffset, presid); 1822 VM_OBJECT_WUNLOCK(obj); 1823 if (had_bogus) 1824 printf("avoided corruption bug in bogus_page/brelse code\n"); 1825 } 1826 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1827 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1828 } 1829 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1830 vfs_vmio_release(bp); 1831 1832 } else if (bp->b_flags & B_VMIO) { 1833 1834 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1835 vfs_vmio_release(bp); 1836 } 1837 1838 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) { 1839 if (bp->b_bufsize != 0) 1840 allocbuf(bp, 0); 1841 if (bp->b_vp != NULL) 1842 brelvp(bp); 1843 } 1844 1845 /* 1846 * If the buffer has junk contents signal it and eventually 1847 * clean up B_DELWRI and diassociate the vnode so that gbincore() 1848 * doesn't find it. 1849 */ 1850 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 1851 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 1852 bp->b_flags |= B_INVAL; 1853 if (bp->b_flags & B_INVAL) { 1854 if (bp->b_flags & B_DELWRI) 1855 bundirty(bp); 1856 if (bp->b_vp) 1857 brelvp(bp); 1858 } 1859 1860 /* buffers with no memory */ 1861 if (bp->b_bufsize == 0) { 1862 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1863 if (bp->b_vflags & BV_BKGRDINPROG) 1864 panic("losing buffer 1"); 1865 if (bp->b_kvasize) 1866 qindex = QUEUE_EMPTYKVA; 1867 else 1868 qindex = QUEUE_EMPTY; 1869 bp->b_flags |= B_AGE; 1870 /* buffers with junk contents */ 1871 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 1872 (bp->b_ioflags & BIO_ERROR)) { 1873 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1874 if (bp->b_vflags & BV_BKGRDINPROG) 1875 panic("losing buffer 2"); 1876 qindex = QUEUE_CLEAN; 1877 bp->b_flags |= B_AGE; 1878 /* remaining buffers */ 1879 } else if (bp->b_flags & B_DELWRI) 1880 qindex = QUEUE_DIRTY; 1881 else 1882 qindex = QUEUE_CLEAN; 1883 1884 binsfree(bp, qindex); 1885 1886 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 1887 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1888 panic("brelse: not dirty"); 1889 /* unlock */ 1890 BUF_UNLOCK(bp); 1891 } 1892 1893 /* 1894 * Release a buffer back to the appropriate queue but do not try to free 1895 * it. The buffer is expected to be used again soon. 1896 * 1897 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1898 * biodone() to requeue an async I/O on completion. It is also used when 1899 * known good buffers need to be requeued but we think we may need the data 1900 * again soon. 1901 * 1902 * XXX we should be able to leave the B_RELBUF hint set on completion. 1903 */ 1904 void 1905 bqrelse(struct buf *bp) 1906 { 1907 int qindex; 1908 1909 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1910 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1911 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1912 1913 if (BUF_LOCKRECURSED(bp)) { 1914 /* do not release to free list */ 1915 BUF_UNLOCK(bp); 1916 return; 1917 } 1918 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1919 1920 if (bp->b_flags & B_MANAGED) { 1921 if (bp->b_flags & B_REMFREE) 1922 bremfreef(bp); 1923 goto out; 1924 } 1925 1926 /* buffers with stale but valid contents */ 1927 if ((bp->b_flags & B_DELWRI) != 0 || (bp->b_vflags & (BV_BKGRDINPROG | 1928 BV_BKGRDERR)) == BV_BKGRDERR) { 1929 BO_LOCK(bp->b_bufobj); 1930 bp->b_vflags &= ~BV_BKGRDERR; 1931 BO_UNLOCK(bp->b_bufobj); 1932 qindex = QUEUE_DIRTY; 1933 } else { 1934 if ((bp->b_flags & B_DELWRI) == 0 && 1935 (bp->b_xflags & BX_VNDIRTY)) 1936 panic("bqrelse: not dirty"); 1937 qindex = QUEUE_CLEAN; 1938 } 1939 binsfree(bp, qindex); 1940 1941 out: 1942 /* unlock */ 1943 BUF_UNLOCK(bp); 1944 } 1945 1946 /* Give pages used by the bp back to the VM system (where possible) */ 1947 static void 1948 vfs_vmio_release(struct buf *bp) 1949 { 1950 vm_object_t obj; 1951 vm_page_t m; 1952 int i; 1953 1954 if (buf_mapped(bp)) { 1955 BUF_CHECK_MAPPED(bp); 1956 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages); 1957 } else 1958 BUF_CHECK_UNMAPPED(bp); 1959 obj = bp->b_bufobj->bo_object; 1960 if (obj != NULL) 1961 VM_OBJECT_WLOCK(obj); 1962 for (i = 0; i < bp->b_npages; i++) { 1963 m = bp->b_pages[i]; 1964 bp->b_pages[i] = NULL; 1965 /* 1966 * In order to keep page LRU ordering consistent, put 1967 * everything on the inactive queue. 1968 */ 1969 vm_page_lock(m); 1970 vm_page_unwire(m, PQ_INACTIVE); 1971 1972 /* 1973 * Might as well free the page if we can and it has 1974 * no valid data. We also free the page if the 1975 * buffer was used for direct I/O 1976 */ 1977 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid) { 1978 if (m->wire_count == 0 && !vm_page_busied(m)) 1979 vm_page_free(m); 1980 } else if (bp->b_flags & B_DIRECT) 1981 vm_page_try_to_free(m); 1982 vm_page_unlock(m); 1983 } 1984 if (obj != NULL) 1985 VM_OBJECT_WUNLOCK(obj); 1986 1987 if (bp->b_bufsize) 1988 bufspaceadjust(bp, 0); 1989 bp->b_npages = 0; 1990 bp->b_flags &= ~B_VMIO; 1991 if (bp->b_vp) 1992 brelvp(bp); 1993 } 1994 1995 /* 1996 * Check to see if a block at a particular lbn is available for a clustered 1997 * write. 1998 */ 1999 static int 2000 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 2001 { 2002 struct buf *bpa; 2003 int match; 2004 2005 match = 0; 2006 2007 /* If the buf isn't in core skip it */ 2008 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 2009 return (0); 2010 2011 /* If the buf is busy we don't want to wait for it */ 2012 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2013 return (0); 2014 2015 /* Only cluster with valid clusterable delayed write buffers */ 2016 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 2017 (B_DELWRI | B_CLUSTEROK)) 2018 goto done; 2019 2020 if (bpa->b_bufsize != size) 2021 goto done; 2022 2023 /* 2024 * Check to see if it is in the expected place on disk and that the 2025 * block has been mapped. 2026 */ 2027 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 2028 match = 1; 2029 done: 2030 BUF_UNLOCK(bpa); 2031 return (match); 2032 } 2033 2034 /* 2035 * vfs_bio_awrite: 2036 * 2037 * Implement clustered async writes for clearing out B_DELWRI buffers. 2038 * This is much better then the old way of writing only one buffer at 2039 * a time. Note that we may not be presented with the buffers in the 2040 * correct order, so we search for the cluster in both directions. 2041 */ 2042 int 2043 vfs_bio_awrite(struct buf *bp) 2044 { 2045 struct bufobj *bo; 2046 int i; 2047 int j; 2048 daddr_t lblkno = bp->b_lblkno; 2049 struct vnode *vp = bp->b_vp; 2050 int ncl; 2051 int nwritten; 2052 int size; 2053 int maxcl; 2054 int gbflags; 2055 2056 bo = &vp->v_bufobj; 2057 gbflags = (bp->b_data == unmapped_buf) ? GB_UNMAPPED : 0; 2058 /* 2059 * right now we support clustered writing only to regular files. If 2060 * we find a clusterable block we could be in the middle of a cluster 2061 * rather then at the beginning. 2062 */ 2063 if ((vp->v_type == VREG) && 2064 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 2065 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 2066 2067 size = vp->v_mount->mnt_stat.f_iosize; 2068 maxcl = MAXPHYS / size; 2069 2070 BO_RLOCK(bo); 2071 for (i = 1; i < maxcl; i++) 2072 if (vfs_bio_clcheck(vp, size, lblkno + i, 2073 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 2074 break; 2075 2076 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 2077 if (vfs_bio_clcheck(vp, size, lblkno - j, 2078 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 2079 break; 2080 BO_RUNLOCK(bo); 2081 --j; 2082 ncl = i + j; 2083 /* 2084 * this is a possible cluster write 2085 */ 2086 if (ncl != 1) { 2087 BUF_UNLOCK(bp); 2088 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl, 2089 gbflags); 2090 return (nwritten); 2091 } 2092 } 2093 bremfree(bp); 2094 bp->b_flags |= B_ASYNC; 2095 /* 2096 * default (old) behavior, writing out only one block 2097 * 2098 * XXX returns b_bufsize instead of b_bcount for nwritten? 2099 */ 2100 nwritten = bp->b_bufsize; 2101 (void) bwrite(bp); 2102 2103 return (nwritten); 2104 } 2105 2106 /* 2107 * Ask the bufdaemon for help, or act as bufdaemon itself, when a 2108 * locked vnode is supplied. 2109 */ 2110 static void 2111 getnewbuf_bufd_help(struct vnode *vp, int gbflags, int slpflag, int slptimeo, 2112 int defrag) 2113 { 2114 struct thread *td; 2115 char *waitmsg; 2116 int error, fl, flags, norunbuf; 2117 2118 mtx_assert(&bqclean, MA_OWNED); 2119 2120 if (defrag) { 2121 flags = VFS_BIO_NEED_BUFSPACE; 2122 waitmsg = "nbufkv"; 2123 } else if (bufspace >= hibufspace) { 2124 waitmsg = "nbufbs"; 2125 flags = VFS_BIO_NEED_BUFSPACE; 2126 } else { 2127 waitmsg = "newbuf"; 2128 flags = VFS_BIO_NEED_ANY; 2129 } 2130 atomic_set_int(&needsbuffer, flags); 2131 mtx_unlock(&bqclean); 2132 2133 bd_speedup(); /* heeeelp */ 2134 if ((gbflags & GB_NOWAIT_BD) != 0) 2135 return; 2136 2137 td = curthread; 2138 rw_wlock(&nblock); 2139 while ((needsbuffer & flags) != 0) { 2140 if (vp != NULL && vp->v_type != VCHR && 2141 (td->td_pflags & TDP_BUFNEED) == 0) { 2142 rw_wunlock(&nblock); 2143 /* 2144 * getblk() is called with a vnode locked, and 2145 * some majority of the dirty buffers may as 2146 * well belong to the vnode. Flushing the 2147 * buffers there would make a progress that 2148 * cannot be achieved by the buf_daemon, that 2149 * cannot lock the vnode. 2150 */ 2151 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) | 2152 (td->td_pflags & TDP_NORUNNINGBUF); 2153 2154 /* 2155 * Play bufdaemon. The getnewbuf() function 2156 * may be called while the thread owns lock 2157 * for another dirty buffer for the same 2158 * vnode, which makes it impossible to use 2159 * VOP_FSYNC() there, due to the buffer lock 2160 * recursion. 2161 */ 2162 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF; 2163 fl = buf_flush(vp, flushbufqtarget); 2164 td->td_pflags &= norunbuf; 2165 rw_wlock(&nblock); 2166 if (fl != 0) 2167 continue; 2168 if ((needsbuffer & flags) == 0) 2169 break; 2170 } 2171 error = rw_sleep(__DEVOLATILE(void *, &needsbuffer), &nblock, 2172 (PRIBIO + 4) | slpflag, waitmsg, slptimeo); 2173 if (error != 0) 2174 break; 2175 } 2176 rw_wunlock(&nblock); 2177 } 2178 2179 static void 2180 getnewbuf_reuse_bp(struct buf *bp, int qindex) 2181 { 2182 2183 CTR6(KTR_BUF, "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d " 2184 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags, 2185 bp->b_kvasize, bp->b_bufsize, qindex); 2186 mtx_assert(&bqclean, MA_NOTOWNED); 2187 2188 /* 2189 * Note: we no longer distinguish between VMIO and non-VMIO 2190 * buffers. 2191 */ 2192 KASSERT((bp->b_flags & B_DELWRI) == 0, 2193 ("delwri buffer %p found in queue %d", bp, qindex)); 2194 2195 if (qindex == QUEUE_CLEAN) { 2196 if (bp->b_flags & B_VMIO) { 2197 bp->b_flags &= ~B_ASYNC; 2198 vfs_vmio_release(bp); 2199 } 2200 if (bp->b_vp != NULL) 2201 brelvp(bp); 2202 } 2203 2204 /* 2205 * Get the rest of the buffer freed up. b_kva* is still valid 2206 * after this operation. 2207 */ 2208 2209 if (bp->b_rcred != NOCRED) { 2210 crfree(bp->b_rcred); 2211 bp->b_rcred = NOCRED; 2212 } 2213 if (bp->b_wcred != NOCRED) { 2214 crfree(bp->b_wcred); 2215 bp->b_wcred = NOCRED; 2216 } 2217 if (!LIST_EMPTY(&bp->b_dep)) 2218 buf_deallocate(bp); 2219 if (bp->b_vflags & BV_BKGRDINPROG) 2220 panic("losing buffer 3"); 2221 KASSERT(bp->b_vp == NULL, ("bp: %p still has vnode %p. qindex: %d", 2222 bp, bp->b_vp, qindex)); 2223 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 2224 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags)); 2225 2226 if (bp->b_bufsize) 2227 allocbuf(bp, 0); 2228 2229 bp->b_flags = 0; 2230 bp->b_ioflags = 0; 2231 bp->b_xflags = 0; 2232 KASSERT((bp->b_flags & B_INFREECNT) == 0, 2233 ("buf %p still counted as free?", bp)); 2234 bp->b_vflags = 0; 2235 bp->b_vp = NULL; 2236 bp->b_blkno = bp->b_lblkno = 0; 2237 bp->b_offset = NOOFFSET; 2238 bp->b_iodone = 0; 2239 bp->b_error = 0; 2240 bp->b_resid = 0; 2241 bp->b_bcount = 0; 2242 bp->b_npages = 0; 2243 bp->b_dirtyoff = bp->b_dirtyend = 0; 2244 bp->b_bufobj = NULL; 2245 bp->b_pin_count = 0; 2246 bp->b_data = bp->b_kvabase; 2247 bp->b_fsprivate1 = NULL; 2248 bp->b_fsprivate2 = NULL; 2249 bp->b_fsprivate3 = NULL; 2250 2251 LIST_INIT(&bp->b_dep); 2252 } 2253 2254 static int flushingbufs; 2255 2256 static struct buf * 2257 getnewbuf_scan(int maxsize, int defrag, int unmapped, int metadata) 2258 { 2259 struct buf *bp, *nbp; 2260 int nqindex, qindex, pass; 2261 2262 KASSERT(!unmapped || !defrag, ("both unmapped and defrag")); 2263 2264 pass = 1; 2265 restart: 2266 atomic_add_int(&getnewbufrestarts, 1); 2267 2268 /* 2269 * Setup for scan. If we do not have enough free buffers, 2270 * we setup a degenerate case that immediately fails. Note 2271 * that if we are specially marked process, we are allowed to 2272 * dip into our reserves. 2273 * 2274 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 2275 * for the allocation of the mapped buffer. For unmapped, the 2276 * easiest is to start with EMPTY outright. 2277 * 2278 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 2279 * However, there are a number of cases (defragging, reusing, ...) 2280 * where we cannot backup. 2281 */ 2282 nbp = NULL; 2283 mtx_lock(&bqclean); 2284 if (!defrag && unmapped) { 2285 nqindex = QUEUE_EMPTY; 2286 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 2287 } 2288 if (nbp == NULL) { 2289 nqindex = QUEUE_EMPTYKVA; 2290 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 2291 } 2292 2293 /* 2294 * If no EMPTYKVA buffers and we are either defragging or 2295 * reusing, locate a CLEAN buffer to free or reuse. If 2296 * bufspace useage is low skip this step so we can allocate a 2297 * new buffer. 2298 */ 2299 if (nbp == NULL && (defrag || bufspace >= lobufspace)) { 2300 nqindex = QUEUE_CLEAN; 2301 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2302 } 2303 2304 /* 2305 * If we could not find or were not allowed to reuse a CLEAN 2306 * buffer, check to see if it is ok to use an EMPTY buffer. 2307 * We can only use an EMPTY buffer if allocating its KVA would 2308 * not otherwise run us out of buffer space. No KVA is needed 2309 * for the unmapped allocation. 2310 */ 2311 if (nbp == NULL && defrag == 0 && (bufspace + maxsize < hibufspace || 2312 metadata)) { 2313 nqindex = QUEUE_EMPTY; 2314 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 2315 } 2316 2317 /* 2318 * All available buffers might be clean, retry ignoring the 2319 * lobufspace as the last resort. 2320 */ 2321 if (nbp == NULL && !TAILQ_EMPTY(&bufqueues[QUEUE_CLEAN])) { 2322 nqindex = QUEUE_CLEAN; 2323 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2324 } 2325 2326 /* 2327 * Run scan, possibly freeing data and/or kva mappings on the fly 2328 * depending. 2329 */ 2330 while ((bp = nbp) != NULL) { 2331 qindex = nqindex; 2332 2333 /* 2334 * Calculate next bp (we can only use it if we do not 2335 * block or do other fancy things). 2336 */ 2337 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 2338 switch (qindex) { 2339 case QUEUE_EMPTY: 2340 nqindex = QUEUE_EMPTYKVA; 2341 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 2342 if (nbp != NULL) 2343 break; 2344 /* FALLTHROUGH */ 2345 case QUEUE_EMPTYKVA: 2346 nqindex = QUEUE_CLEAN; 2347 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2348 if (nbp != NULL) 2349 break; 2350 /* FALLTHROUGH */ 2351 case QUEUE_CLEAN: 2352 if (metadata && pass == 1) { 2353 pass = 2; 2354 nqindex = QUEUE_EMPTY; 2355 nbp = TAILQ_FIRST( 2356 &bufqueues[QUEUE_EMPTY]); 2357 } 2358 /* 2359 * nbp is NULL. 2360 */ 2361 break; 2362 } 2363 } 2364 /* 2365 * If we are defragging then we need a buffer with 2366 * b_kvasize != 0. This situation occurs when we 2367 * have many unmapped bufs. 2368 */ 2369 if (defrag && bp->b_kvasize == 0) 2370 continue; 2371 2372 /* 2373 * Start freeing the bp. This is somewhat involved. nbp 2374 * remains valid only for QUEUE_EMPTY[KVA] bp's. 2375 */ 2376 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2377 continue; 2378 /* 2379 * BKGRDINPROG can only be set with the buf and bufobj 2380 * locks both held. We tolerate a race to clear it here. 2381 */ 2382 if (bp->b_vflags & BV_BKGRDINPROG) { 2383 BUF_UNLOCK(bp); 2384 continue; 2385 } 2386 2387 /* 2388 * Requeue the background write buffer with error. 2389 */ 2390 if ((bp->b_vflags & BV_BKGRDERR) != 0) { 2391 bremfreel(bp); 2392 mtx_unlock(&bqclean); 2393 bqrelse(bp); 2394 continue; 2395 } 2396 2397 KASSERT(bp->b_qindex == qindex, 2398 ("getnewbuf: inconsistent queue %d bp %p", qindex, bp)); 2399 2400 bremfreel(bp); 2401 mtx_unlock(&bqclean); 2402 /* 2403 * NOTE: nbp is now entirely invalid. We can only restart 2404 * the scan from this point on. 2405 */ 2406 2407 getnewbuf_reuse_bp(bp, qindex); 2408 mtx_assert(&bqclean, MA_NOTOWNED); 2409 2410 /* 2411 * If we are defragging then free the buffer. 2412 */ 2413 if (defrag) { 2414 bp->b_flags |= B_INVAL; 2415 bufkvafree(bp); 2416 brelse(bp); 2417 defrag = 0; 2418 goto restart; 2419 } 2420 2421 /* 2422 * Notify any waiters for the buffer lock about 2423 * identity change by freeing the buffer. 2424 */ 2425 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp)) { 2426 bp->b_flags |= B_INVAL; 2427 bufkvafree(bp); 2428 brelse(bp); 2429 goto restart; 2430 } 2431 2432 if (metadata) 2433 break; 2434 2435 /* 2436 * If we are overcomitted then recover the buffer and its 2437 * KVM space. This occurs in rare situations when multiple 2438 * processes are blocked in getnewbuf() or allocbuf(). 2439 */ 2440 if (bufspace >= hibufspace) 2441 flushingbufs = 1; 2442 if (flushingbufs && bp->b_kvasize != 0) { 2443 bp->b_flags |= B_INVAL; 2444 bufkvafree(bp); 2445 brelse(bp); 2446 goto restart; 2447 } 2448 if (bufspace < lobufspace) 2449 flushingbufs = 0; 2450 break; 2451 } 2452 return (bp); 2453 } 2454 2455 /* 2456 * getnewbuf: 2457 * 2458 * Find and initialize a new buffer header, freeing up existing buffers 2459 * in the bufqueues as necessary. The new buffer is returned locked. 2460 * 2461 * Important: B_INVAL is not set. If the caller wishes to throw the 2462 * buffer away, the caller must set B_INVAL prior to calling brelse(). 2463 * 2464 * We block if: 2465 * We have insufficient buffer headers 2466 * We have insufficient buffer space 2467 * buffer_arena is too fragmented ( space reservation fails ) 2468 * If we have to flush dirty buffers ( but we try to avoid this ) 2469 */ 2470 static struct buf * 2471 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int size, int maxsize, 2472 int gbflags) 2473 { 2474 struct buf *bp; 2475 int defrag, metadata; 2476 2477 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 2478 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 2479 if (!unmapped_buf_allowed) 2480 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC); 2481 2482 defrag = 0; 2483 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 || 2484 vp->v_type == VCHR) 2485 metadata = 1; 2486 else 2487 metadata = 0; 2488 /* 2489 * We can't afford to block since we might be holding a vnode lock, 2490 * which may prevent system daemons from running. We deal with 2491 * low-memory situations by proactively returning memory and running 2492 * async I/O rather then sync I/O. 2493 */ 2494 atomic_add_int(&getnewbufcalls, 1); 2495 atomic_subtract_int(&getnewbufrestarts, 1); 2496 restart: 2497 bp = getnewbuf_scan(maxsize, defrag, (gbflags & (GB_UNMAPPED | 2498 GB_KVAALLOC)) == GB_UNMAPPED, metadata); 2499 if (bp != NULL) 2500 defrag = 0; 2501 2502 /* 2503 * If we exhausted our list, sleep as appropriate. We may have to 2504 * wakeup various daemons and write out some dirty buffers. 2505 * 2506 * Generally we are sleeping due to insufficient buffer space. 2507 */ 2508 if (bp == NULL) { 2509 mtx_assert(&bqclean, MA_OWNED); 2510 getnewbuf_bufd_help(vp, gbflags, slpflag, slptimeo, defrag); 2511 mtx_assert(&bqclean, MA_NOTOWNED); 2512 } else if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == GB_UNMAPPED) { 2513 mtx_assert(&bqclean, MA_NOTOWNED); 2514 2515 bufkvafree(bp); 2516 atomic_add_int(&bufreusecnt, 1); 2517 } else { 2518 mtx_assert(&bqclean, MA_NOTOWNED); 2519 2520 /* 2521 * We finally have a valid bp. We aren't quite out of the 2522 * woods, we still have to reserve kva space. In order to 2523 * keep fragmentation sane we only allocate kva in BKVASIZE 2524 * chunks. 2525 */ 2526 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2527 2528 if (maxsize != bp->b_kvasize && 2529 bufkvaalloc(bp, maxsize, gbflags)) { 2530 defrag = 1; 2531 bp->b_flags |= B_INVAL; 2532 brelse(bp); 2533 goto restart; 2534 } else if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == 2535 (GB_UNMAPPED | GB_KVAALLOC)) { 2536 bp->b_data = unmapped_buf; 2537 BUF_CHECK_UNMAPPED(bp); 2538 } 2539 atomic_add_int(&bufreusecnt, 1); 2540 } 2541 return (bp); 2542 } 2543 2544 /* 2545 * buf_daemon: 2546 * 2547 * buffer flushing daemon. Buffers are normally flushed by the 2548 * update daemon but if it cannot keep up this process starts to 2549 * take the load in an attempt to prevent getnewbuf() from blocking. 2550 */ 2551 2552 static struct kproc_desc buf_kp = { 2553 "bufdaemon", 2554 buf_daemon, 2555 &bufdaemonproc 2556 }; 2557 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 2558 2559 static int 2560 buf_flush(struct vnode *vp, int target) 2561 { 2562 int flushed; 2563 2564 flushed = flushbufqueues(vp, target, 0); 2565 if (flushed == 0) { 2566 /* 2567 * Could not find any buffers without rollback 2568 * dependencies, so just write the first one 2569 * in the hopes of eventually making progress. 2570 */ 2571 if (vp != NULL && target > 2) 2572 target /= 2; 2573 flushbufqueues(vp, target, 1); 2574 } 2575 return (flushed); 2576 } 2577 2578 static void 2579 buf_daemon() 2580 { 2581 int lodirty; 2582 2583 /* 2584 * This process needs to be suspended prior to shutdown sync. 2585 */ 2586 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2587 SHUTDOWN_PRI_LAST); 2588 2589 /* 2590 * This process is allowed to take the buffer cache to the limit 2591 */ 2592 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 2593 mtx_lock(&bdlock); 2594 for (;;) { 2595 bd_request = 0; 2596 mtx_unlock(&bdlock); 2597 2598 kproc_suspend_check(bufdaemonproc); 2599 lodirty = lodirtybuffers; 2600 if (bd_speedupreq) { 2601 lodirty = numdirtybuffers / 2; 2602 bd_speedupreq = 0; 2603 } 2604 /* 2605 * Do the flush. Limit the amount of in-transit I/O we 2606 * allow to build up, otherwise we would completely saturate 2607 * the I/O system. 2608 */ 2609 while (numdirtybuffers > lodirty) { 2610 if (buf_flush(NULL, numdirtybuffers - lodirty) == 0) 2611 break; 2612 kern_yield(PRI_USER); 2613 } 2614 2615 /* 2616 * Only clear bd_request if we have reached our low water 2617 * mark. The buf_daemon normally waits 1 second and 2618 * then incrementally flushes any dirty buffers that have 2619 * built up, within reason. 2620 * 2621 * If we were unable to hit our low water mark and couldn't 2622 * find any flushable buffers, we sleep for a short period 2623 * to avoid endless loops on unlockable buffers. 2624 */ 2625 mtx_lock(&bdlock); 2626 if (numdirtybuffers <= lodirtybuffers) { 2627 /* 2628 * We reached our low water mark, reset the 2629 * request and sleep until we are needed again. 2630 * The sleep is just so the suspend code works. 2631 */ 2632 bd_request = 0; 2633 /* 2634 * Do an extra wakeup in case dirty threshold 2635 * changed via sysctl and the explicit transition 2636 * out of shortfall was missed. 2637 */ 2638 bdirtywakeup(); 2639 if (runningbufspace <= lorunningspace) 2640 runningwakeup(); 2641 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 2642 } else { 2643 /* 2644 * We couldn't find any flushable dirty buffers but 2645 * still have too many dirty buffers, we 2646 * have to sleep and try again. (rare) 2647 */ 2648 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 2649 } 2650 } 2651 } 2652 2653 /* 2654 * flushbufqueues: 2655 * 2656 * Try to flush a buffer in the dirty queue. We must be careful to 2657 * free up B_INVAL buffers instead of write them, which NFS is 2658 * particularly sensitive to. 2659 */ 2660 static int flushwithdeps = 0; 2661 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 2662 0, "Number of buffers flushed with dependecies that require rollbacks"); 2663 2664 static int 2665 flushbufqueues(struct vnode *lvp, int target, int flushdeps) 2666 { 2667 struct buf *sentinel; 2668 struct vnode *vp; 2669 struct mount *mp; 2670 struct buf *bp; 2671 int hasdeps; 2672 int flushed; 2673 int queue; 2674 int error; 2675 bool unlock; 2676 2677 flushed = 0; 2678 queue = QUEUE_DIRTY; 2679 bp = NULL; 2680 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 2681 sentinel->b_qindex = QUEUE_SENTINEL; 2682 mtx_lock(&bqdirty); 2683 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist); 2684 mtx_unlock(&bqdirty); 2685 while (flushed != target) { 2686 maybe_yield(); 2687 mtx_lock(&bqdirty); 2688 bp = TAILQ_NEXT(sentinel, b_freelist); 2689 if (bp != NULL) { 2690 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2691 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel, 2692 b_freelist); 2693 } else { 2694 mtx_unlock(&bqdirty); 2695 break; 2696 } 2697 /* 2698 * Skip sentinels inserted by other invocations of the 2699 * flushbufqueues(), taking care to not reorder them. 2700 * 2701 * Only flush the buffers that belong to the 2702 * vnode locked by the curthread. 2703 */ 2704 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL && 2705 bp->b_vp != lvp)) { 2706 mtx_unlock(&bqdirty); 2707 continue; 2708 } 2709 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL); 2710 mtx_unlock(&bqdirty); 2711 if (error != 0) 2712 continue; 2713 if (bp->b_pin_count > 0) { 2714 BUF_UNLOCK(bp); 2715 continue; 2716 } 2717 /* 2718 * BKGRDINPROG can only be set with the buf and bufobj 2719 * locks both held. We tolerate a race to clear it here. 2720 */ 2721 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 2722 (bp->b_flags & B_DELWRI) == 0) { 2723 BUF_UNLOCK(bp); 2724 continue; 2725 } 2726 if (bp->b_flags & B_INVAL) { 2727 bremfreef(bp); 2728 brelse(bp); 2729 flushed++; 2730 continue; 2731 } 2732 2733 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 2734 if (flushdeps == 0) { 2735 BUF_UNLOCK(bp); 2736 continue; 2737 } 2738 hasdeps = 1; 2739 } else 2740 hasdeps = 0; 2741 /* 2742 * We must hold the lock on a vnode before writing 2743 * one of its buffers. Otherwise we may confuse, or 2744 * in the case of a snapshot vnode, deadlock the 2745 * system. 2746 * 2747 * The lock order here is the reverse of the normal 2748 * of vnode followed by buf lock. This is ok because 2749 * the NOWAIT will prevent deadlock. 2750 */ 2751 vp = bp->b_vp; 2752 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 2753 BUF_UNLOCK(bp); 2754 continue; 2755 } 2756 if (lvp == NULL) { 2757 unlock = true; 2758 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT); 2759 } else { 2760 ASSERT_VOP_LOCKED(vp, "getbuf"); 2761 unlock = false; 2762 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 : 2763 vn_lock(vp, LK_TRYUPGRADE); 2764 } 2765 if (error == 0) { 2766 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 2767 bp, bp->b_vp, bp->b_flags); 2768 if (curproc == bufdaemonproc) { 2769 vfs_bio_awrite(bp); 2770 } else { 2771 bremfree(bp); 2772 bwrite(bp); 2773 notbufdflushes++; 2774 } 2775 vn_finished_write(mp); 2776 if (unlock) 2777 VOP_UNLOCK(vp, 0); 2778 flushwithdeps += hasdeps; 2779 flushed++; 2780 2781 /* 2782 * Sleeping on runningbufspace while holding 2783 * vnode lock leads to deadlock. 2784 */ 2785 if (curproc == bufdaemonproc && 2786 runningbufspace > hirunningspace) 2787 waitrunningbufspace(); 2788 continue; 2789 } 2790 vn_finished_write(mp); 2791 BUF_UNLOCK(bp); 2792 } 2793 mtx_lock(&bqdirty); 2794 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2795 mtx_unlock(&bqdirty); 2796 free(sentinel, M_TEMP); 2797 return (flushed); 2798 } 2799 2800 /* 2801 * Check to see if a block is currently memory resident. 2802 */ 2803 struct buf * 2804 incore(struct bufobj *bo, daddr_t blkno) 2805 { 2806 struct buf *bp; 2807 2808 BO_RLOCK(bo); 2809 bp = gbincore(bo, blkno); 2810 BO_RUNLOCK(bo); 2811 return (bp); 2812 } 2813 2814 /* 2815 * Returns true if no I/O is needed to access the 2816 * associated VM object. This is like incore except 2817 * it also hunts around in the VM system for the data. 2818 */ 2819 2820 static int 2821 inmem(struct vnode * vp, daddr_t blkno) 2822 { 2823 vm_object_t obj; 2824 vm_offset_t toff, tinc, size; 2825 vm_page_t m; 2826 vm_ooffset_t off; 2827 2828 ASSERT_VOP_LOCKED(vp, "inmem"); 2829 2830 if (incore(&vp->v_bufobj, blkno)) 2831 return 1; 2832 if (vp->v_mount == NULL) 2833 return 0; 2834 obj = vp->v_object; 2835 if (obj == NULL) 2836 return (0); 2837 2838 size = PAGE_SIZE; 2839 if (size > vp->v_mount->mnt_stat.f_iosize) 2840 size = vp->v_mount->mnt_stat.f_iosize; 2841 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2842 2843 VM_OBJECT_RLOCK(obj); 2844 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2845 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2846 if (!m) 2847 goto notinmem; 2848 tinc = size; 2849 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2850 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2851 if (vm_page_is_valid(m, 2852 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2853 goto notinmem; 2854 } 2855 VM_OBJECT_RUNLOCK(obj); 2856 return 1; 2857 2858 notinmem: 2859 VM_OBJECT_RUNLOCK(obj); 2860 return (0); 2861 } 2862 2863 /* 2864 * Set the dirty range for a buffer based on the status of the dirty 2865 * bits in the pages comprising the buffer. The range is limited 2866 * to the size of the buffer. 2867 * 2868 * Tell the VM system that the pages associated with this buffer 2869 * are clean. This is used for delayed writes where the data is 2870 * going to go to disk eventually without additional VM intevention. 2871 * 2872 * Note that while we only really need to clean through to b_bcount, we 2873 * just go ahead and clean through to b_bufsize. 2874 */ 2875 static void 2876 vfs_clean_pages_dirty_buf(struct buf *bp) 2877 { 2878 vm_ooffset_t foff, noff, eoff; 2879 vm_page_t m; 2880 int i; 2881 2882 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 2883 return; 2884 2885 foff = bp->b_offset; 2886 KASSERT(bp->b_offset != NOOFFSET, 2887 ("vfs_clean_pages_dirty_buf: no buffer offset")); 2888 2889 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 2890 vfs_drain_busy_pages(bp); 2891 vfs_setdirty_locked_object(bp); 2892 for (i = 0; i < bp->b_npages; i++) { 2893 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2894 eoff = noff; 2895 if (eoff > bp->b_offset + bp->b_bufsize) 2896 eoff = bp->b_offset + bp->b_bufsize; 2897 m = bp->b_pages[i]; 2898 vfs_page_set_validclean(bp, foff, m); 2899 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 2900 foff = noff; 2901 } 2902 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 2903 } 2904 2905 static void 2906 vfs_setdirty_locked_object(struct buf *bp) 2907 { 2908 vm_object_t object; 2909 int i; 2910 2911 object = bp->b_bufobj->bo_object; 2912 VM_OBJECT_ASSERT_WLOCKED(object); 2913 2914 /* 2915 * We qualify the scan for modified pages on whether the 2916 * object has been flushed yet. 2917 */ 2918 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) { 2919 vm_offset_t boffset; 2920 vm_offset_t eoffset; 2921 2922 /* 2923 * test the pages to see if they have been modified directly 2924 * by users through the VM system. 2925 */ 2926 for (i = 0; i < bp->b_npages; i++) 2927 vm_page_test_dirty(bp->b_pages[i]); 2928 2929 /* 2930 * Calculate the encompassing dirty range, boffset and eoffset, 2931 * (eoffset - boffset) bytes. 2932 */ 2933 2934 for (i = 0; i < bp->b_npages; i++) { 2935 if (bp->b_pages[i]->dirty) 2936 break; 2937 } 2938 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2939 2940 for (i = bp->b_npages - 1; i >= 0; --i) { 2941 if (bp->b_pages[i]->dirty) { 2942 break; 2943 } 2944 } 2945 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2946 2947 /* 2948 * Fit it to the buffer. 2949 */ 2950 2951 if (eoffset > bp->b_bcount) 2952 eoffset = bp->b_bcount; 2953 2954 /* 2955 * If we have a good dirty range, merge with the existing 2956 * dirty range. 2957 */ 2958 2959 if (boffset < eoffset) { 2960 if (bp->b_dirtyoff > boffset) 2961 bp->b_dirtyoff = boffset; 2962 if (bp->b_dirtyend < eoffset) 2963 bp->b_dirtyend = eoffset; 2964 } 2965 } 2966 } 2967 2968 /* 2969 * Allocate the KVA mapping for an existing buffer. 2970 * If an unmapped buffer is provided but a mapped buffer is requested, take 2971 * also care to properly setup mappings between pages and KVA. 2972 */ 2973 static void 2974 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags) 2975 { 2976 struct buf *scratch_bp; 2977 int bsize, maxsize, need_mapping, need_kva; 2978 off_t offset; 2979 2980 need_mapping = bp->b_data == unmapped_buf && 2981 (gbflags & GB_UNMAPPED) == 0; 2982 need_kva = bp->b_kvabase == unmapped_buf && 2983 bp->b_data == unmapped_buf && 2984 (gbflags & GB_KVAALLOC) != 0; 2985 if (!need_mapping && !need_kva) 2986 return; 2987 2988 BUF_CHECK_UNMAPPED(bp); 2989 2990 if (need_mapping && bp->b_kvabase != unmapped_buf) { 2991 /* 2992 * Buffer is not mapped, but the KVA was already 2993 * reserved at the time of the instantiation. Use the 2994 * allocated space. 2995 */ 2996 goto has_addr; 2997 } 2998 2999 /* 3000 * Calculate the amount of the address space we would reserve 3001 * if the buffer was mapped. 3002 */ 3003 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize; 3004 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3005 offset = blkno * bsize; 3006 maxsize = size + (offset & PAGE_MASK); 3007 maxsize = imax(maxsize, bsize); 3008 3009 mapping_loop: 3010 if (bufkvaalloc(bp, maxsize, gbflags)) { 3011 /* 3012 * Request defragmentation. getnewbuf() returns us the 3013 * allocated space by the scratch buffer KVA. 3014 */ 3015 scratch_bp = getnewbuf(bp->b_vp, 0, 0, size, maxsize, gbflags | 3016 (GB_UNMAPPED | GB_KVAALLOC)); 3017 if (scratch_bp == NULL) { 3018 if ((gbflags & GB_NOWAIT_BD) != 0) { 3019 /* 3020 * XXXKIB: defragmentation cannot 3021 * succeed, not sure what else to do. 3022 */ 3023 panic("GB_NOWAIT_BD and GB_UNMAPPED %p", bp); 3024 } 3025 atomic_add_int(&mappingrestarts, 1); 3026 goto mapping_loop; 3027 } 3028 KASSERT(scratch_bp->b_kvabase != unmapped_buf, 3029 ("scratch bp has no KVA %p", scratch_bp)); 3030 /* Grab pointers. */ 3031 bp->b_kvabase = scratch_bp->b_kvabase; 3032 bp->b_kvasize = scratch_bp->b_kvasize; 3033 bp->b_data = scratch_bp->b_data; 3034 3035 /* Get rid of the scratch buffer. */ 3036 scratch_bp->b_kvasize = 0; 3037 scratch_bp->b_flags |= B_INVAL; 3038 scratch_bp->b_data = scratch_bp->b_kvabase = unmapped_buf; 3039 brelse(scratch_bp); 3040 } 3041 has_addr: 3042 if (need_mapping) { 3043 /* b_offset is handled by bpmap_qenter. */ 3044 bp->b_data = bp->b_kvabase; 3045 BUF_CHECK_MAPPED(bp); 3046 bpmap_qenter(bp); 3047 } 3048 } 3049 3050 /* 3051 * getblk: 3052 * 3053 * Get a block given a specified block and offset into a file/device. 3054 * The buffers B_DONE bit will be cleared on return, making it almost 3055 * ready for an I/O initiation. B_INVAL may or may not be set on 3056 * return. The caller should clear B_INVAL prior to initiating a 3057 * READ. 3058 * 3059 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 3060 * an existing buffer. 3061 * 3062 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 3063 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 3064 * and then cleared based on the backing VM. If the previous buffer is 3065 * non-0-sized but invalid, B_CACHE will be cleared. 3066 * 3067 * If getblk() must create a new buffer, the new buffer is returned with 3068 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 3069 * case it is returned with B_INVAL clear and B_CACHE set based on the 3070 * backing VM. 3071 * 3072 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 3073 * B_CACHE bit is clear. 3074 * 3075 * What this means, basically, is that the caller should use B_CACHE to 3076 * determine whether the buffer is fully valid or not and should clear 3077 * B_INVAL prior to issuing a read. If the caller intends to validate 3078 * the buffer by loading its data area with something, the caller needs 3079 * to clear B_INVAL. If the caller does this without issuing an I/O, 3080 * the caller should set B_CACHE ( as an optimization ), else the caller 3081 * should issue the I/O and biodone() will set B_CACHE if the I/O was 3082 * a write attempt or if it was a successfull read. If the caller 3083 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 3084 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 3085 */ 3086 struct buf * 3087 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3088 int flags) 3089 { 3090 struct buf *bp; 3091 struct bufobj *bo; 3092 int bsize, error, maxsize, vmio; 3093 off_t offset; 3094 3095 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 3096 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3097 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3098 ASSERT_VOP_LOCKED(vp, "getblk"); 3099 if (size > MAXBCACHEBUF) 3100 panic("getblk: size(%d) > MAXBCACHEBUF(%d)\n", size, 3101 MAXBCACHEBUF); 3102 if (!unmapped_buf_allowed) 3103 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3104 3105 bo = &vp->v_bufobj; 3106 loop: 3107 BO_RLOCK(bo); 3108 bp = gbincore(bo, blkno); 3109 if (bp != NULL) { 3110 int lockflags; 3111 /* 3112 * Buffer is in-core. If the buffer is not busy nor managed, 3113 * it must be on a queue. 3114 */ 3115 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 3116 3117 if (flags & GB_LOCK_NOWAIT) 3118 lockflags |= LK_NOWAIT; 3119 3120 error = BUF_TIMELOCK(bp, lockflags, 3121 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo); 3122 3123 /* 3124 * If we slept and got the lock we have to restart in case 3125 * the buffer changed identities. 3126 */ 3127 if (error == ENOLCK) 3128 goto loop; 3129 /* We timed out or were interrupted. */ 3130 else if (error) 3131 return (NULL); 3132 /* If recursed, assume caller knows the rules. */ 3133 else if (BUF_LOCKRECURSED(bp)) 3134 goto end; 3135 3136 /* 3137 * The buffer is locked. B_CACHE is cleared if the buffer is 3138 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 3139 * and for a VMIO buffer B_CACHE is adjusted according to the 3140 * backing VM cache. 3141 */ 3142 if (bp->b_flags & B_INVAL) 3143 bp->b_flags &= ~B_CACHE; 3144 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 3145 bp->b_flags |= B_CACHE; 3146 if (bp->b_flags & B_MANAGED) 3147 MPASS(bp->b_qindex == QUEUE_NONE); 3148 else 3149 bremfree(bp); 3150 3151 /* 3152 * check for size inconsistencies for non-VMIO case. 3153 */ 3154 if (bp->b_bcount != size) { 3155 if ((bp->b_flags & B_VMIO) == 0 || 3156 (size > bp->b_kvasize)) { 3157 if (bp->b_flags & B_DELWRI) { 3158 /* 3159 * If buffer is pinned and caller does 3160 * not want sleep waiting for it to be 3161 * unpinned, bail out 3162 * */ 3163 if (bp->b_pin_count > 0) { 3164 if (flags & GB_LOCK_NOWAIT) { 3165 bqrelse(bp); 3166 return (NULL); 3167 } else { 3168 bunpin_wait(bp); 3169 } 3170 } 3171 bp->b_flags |= B_NOCACHE; 3172 bwrite(bp); 3173 } else { 3174 if (LIST_EMPTY(&bp->b_dep)) { 3175 bp->b_flags |= B_RELBUF; 3176 brelse(bp); 3177 } else { 3178 bp->b_flags |= B_NOCACHE; 3179 bwrite(bp); 3180 } 3181 } 3182 goto loop; 3183 } 3184 } 3185 3186 /* 3187 * Handle the case of unmapped buffer which should 3188 * become mapped, or the buffer for which KVA 3189 * reservation is requested. 3190 */ 3191 bp_unmapped_get_kva(bp, blkno, size, flags); 3192 3193 /* 3194 * If the size is inconsistant in the VMIO case, we can resize 3195 * the buffer. This might lead to B_CACHE getting set or 3196 * cleared. If the size has not changed, B_CACHE remains 3197 * unchanged from its previous state. 3198 */ 3199 if (bp->b_bcount != size) 3200 allocbuf(bp, size); 3201 3202 KASSERT(bp->b_offset != NOOFFSET, 3203 ("getblk: no buffer offset")); 3204 3205 /* 3206 * A buffer with B_DELWRI set and B_CACHE clear must 3207 * be committed before we can return the buffer in 3208 * order to prevent the caller from issuing a read 3209 * ( due to B_CACHE not being set ) and overwriting 3210 * it. 3211 * 3212 * Most callers, including NFS and FFS, need this to 3213 * operate properly either because they assume they 3214 * can issue a read if B_CACHE is not set, or because 3215 * ( for example ) an uncached B_DELWRI might loop due 3216 * to softupdates re-dirtying the buffer. In the latter 3217 * case, B_CACHE is set after the first write completes, 3218 * preventing further loops. 3219 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 3220 * above while extending the buffer, we cannot allow the 3221 * buffer to remain with B_CACHE set after the write 3222 * completes or it will represent a corrupt state. To 3223 * deal with this we set B_NOCACHE to scrap the buffer 3224 * after the write. 3225 * 3226 * We might be able to do something fancy, like setting 3227 * B_CACHE in bwrite() except if B_DELWRI is already set, 3228 * so the below call doesn't set B_CACHE, but that gets real 3229 * confusing. This is much easier. 3230 */ 3231 3232 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 3233 bp->b_flags |= B_NOCACHE; 3234 bwrite(bp); 3235 goto loop; 3236 } 3237 bp->b_flags &= ~B_DONE; 3238 } else { 3239 /* 3240 * Buffer is not in-core, create new buffer. The buffer 3241 * returned by getnewbuf() is locked. Note that the returned 3242 * buffer is also considered valid (not marked B_INVAL). 3243 */ 3244 BO_RUNLOCK(bo); 3245 /* 3246 * If the user does not want us to create the buffer, bail out 3247 * here. 3248 */ 3249 if (flags & GB_NOCREAT) 3250 return NULL; 3251 if (numfreebuffers == 0 && TD_IS_IDLETHREAD(curthread)) 3252 return NULL; 3253 3254 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize; 3255 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3256 offset = blkno * bsize; 3257 vmio = vp->v_object != NULL; 3258 if (vmio) { 3259 maxsize = size + (offset & PAGE_MASK); 3260 } else { 3261 maxsize = size; 3262 /* Do not allow non-VMIO notmapped buffers. */ 3263 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3264 } 3265 maxsize = imax(maxsize, bsize); 3266 3267 bp = getnewbuf(vp, slpflag, slptimeo, size, maxsize, flags); 3268 if (bp == NULL) { 3269 if (slpflag || slptimeo) 3270 return NULL; 3271 goto loop; 3272 } 3273 3274 /* 3275 * This code is used to make sure that a buffer is not 3276 * created while the getnewbuf routine is blocked. 3277 * This can be a problem whether the vnode is locked or not. 3278 * If the buffer is created out from under us, we have to 3279 * throw away the one we just created. 3280 * 3281 * Note: this must occur before we associate the buffer 3282 * with the vp especially considering limitations in 3283 * the splay tree implementation when dealing with duplicate 3284 * lblkno's. 3285 */ 3286 BO_LOCK(bo); 3287 if (gbincore(bo, blkno)) { 3288 BO_UNLOCK(bo); 3289 bp->b_flags |= B_INVAL; 3290 brelse(bp); 3291 goto loop; 3292 } 3293 3294 /* 3295 * Insert the buffer into the hash, so that it can 3296 * be found by incore. 3297 */ 3298 bp->b_blkno = bp->b_lblkno = blkno; 3299 bp->b_offset = offset; 3300 bgetvp(vp, bp); 3301 BO_UNLOCK(bo); 3302 3303 /* 3304 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 3305 * buffer size starts out as 0, B_CACHE will be set by 3306 * allocbuf() for the VMIO case prior to it testing the 3307 * backing store for validity. 3308 */ 3309 3310 if (vmio) { 3311 bp->b_flags |= B_VMIO; 3312 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 3313 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 3314 bp, vp->v_object, bp->b_bufobj->bo_object)); 3315 } else { 3316 bp->b_flags &= ~B_VMIO; 3317 KASSERT(bp->b_bufobj->bo_object == NULL, 3318 ("ARGH! has b_bufobj->bo_object %p %p\n", 3319 bp, bp->b_bufobj->bo_object)); 3320 BUF_CHECK_MAPPED(bp); 3321 } 3322 3323 allocbuf(bp, size); 3324 bp->b_flags &= ~B_DONE; 3325 } 3326 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 3327 BUF_ASSERT_HELD(bp); 3328 end: 3329 KASSERT(bp->b_bufobj == bo, 3330 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 3331 return (bp); 3332 } 3333 3334 /* 3335 * Get an empty, disassociated buffer of given size. The buffer is initially 3336 * set to B_INVAL. 3337 */ 3338 struct buf * 3339 geteblk(int size, int flags) 3340 { 3341 struct buf *bp; 3342 int maxsize; 3343 3344 maxsize = (size + BKVAMASK) & ~BKVAMASK; 3345 while ((bp = getnewbuf(NULL, 0, 0, size, maxsize, flags)) == NULL) { 3346 if ((flags & GB_NOWAIT_BD) && 3347 (curthread->td_pflags & TDP_BUFNEED) != 0) 3348 return (NULL); 3349 } 3350 allocbuf(bp, size); 3351 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 3352 BUF_ASSERT_HELD(bp); 3353 return (bp); 3354 } 3355 3356 /* 3357 * This code constitutes the buffer memory from either anonymous system 3358 * memory (in the case of non-VMIO operations) or from an associated 3359 * VM object (in the case of VMIO operations). This code is able to 3360 * resize a buffer up or down. 3361 * 3362 * Note that this code is tricky, and has many complications to resolve 3363 * deadlock or inconsistant data situations. Tread lightly!!! 3364 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 3365 * the caller. Calling this code willy nilly can result in the loss of data. 3366 * 3367 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 3368 * B_CACHE for the non-VMIO case. 3369 */ 3370 3371 int 3372 allocbuf(struct buf *bp, int size) 3373 { 3374 int newbsize, mbsize; 3375 int i; 3376 3377 BUF_ASSERT_HELD(bp); 3378 3379 if (bp->b_kvasize != 0 && bp->b_kvasize < size) 3380 panic("allocbuf: buffer too small"); 3381 3382 if ((bp->b_flags & B_VMIO) == 0) { 3383 caddr_t origbuf; 3384 int origbufsize; 3385 /* 3386 * Just get anonymous memory from the kernel. Don't 3387 * mess with B_CACHE. 3388 */ 3389 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3390 if (bp->b_flags & B_MALLOC) 3391 newbsize = mbsize; 3392 else 3393 newbsize = round_page(size); 3394 3395 if (newbsize < bp->b_bufsize) { 3396 /* 3397 * malloced buffers are not shrunk 3398 */ 3399 if (bp->b_flags & B_MALLOC) { 3400 if (newbsize) { 3401 bp->b_bcount = size; 3402 } else { 3403 free(bp->b_data, M_BIOBUF); 3404 bufmallocadjust(bp, 0); 3405 bp->b_data = bp->b_kvabase; 3406 bp->b_bcount = 0; 3407 bp->b_flags &= ~B_MALLOC; 3408 } 3409 return 1; 3410 } 3411 vm_hold_free_pages(bp, newbsize); 3412 } else if (newbsize > bp->b_bufsize) { 3413 /* 3414 * We only use malloced memory on the first allocation. 3415 * and revert to page-allocated memory when the buffer 3416 * grows. 3417 */ 3418 /* 3419 * There is a potential smp race here that could lead 3420 * to bufmallocspace slightly passing the max. It 3421 * is probably extremely rare and not worth worrying 3422 * over. 3423 */ 3424 if ((bufmallocspace < maxbufmallocspace) && 3425 (bp->b_bufsize == 0) && 3426 (mbsize <= PAGE_SIZE/2)) { 3427 3428 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 3429 bp->b_bcount = size; 3430 bp->b_flags |= B_MALLOC; 3431 bufmallocadjust(bp, mbsize); 3432 return 1; 3433 } 3434 origbuf = NULL; 3435 origbufsize = 0; 3436 /* 3437 * If the buffer is growing on its other-than-first 3438 * allocation then we revert to the page-allocation 3439 * scheme. 3440 */ 3441 if (bp->b_flags & B_MALLOC) { 3442 origbuf = bp->b_data; 3443 origbufsize = bp->b_bufsize; 3444 bp->b_data = bp->b_kvabase; 3445 bufmallocadjust(bp, 0); 3446 bp->b_flags &= ~B_MALLOC; 3447 newbsize = round_page(newbsize); 3448 } 3449 vm_hold_load_pages( 3450 bp, 3451 (vm_offset_t) bp->b_data + bp->b_bufsize, 3452 (vm_offset_t) bp->b_data + newbsize); 3453 if (origbuf) { 3454 bcopy(origbuf, bp->b_data, origbufsize); 3455 free(origbuf, M_BIOBUF); 3456 } 3457 } 3458 } else { 3459 int desiredpages; 3460 3461 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3462 desiredpages = (size == 0) ? 0 : 3463 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 3464 3465 if (bp->b_flags & B_MALLOC) 3466 panic("allocbuf: VMIO buffer can't be malloced"); 3467 /* 3468 * Set B_CACHE initially if buffer is 0 length or will become 3469 * 0-length. 3470 */ 3471 if (size == 0 || bp->b_bufsize == 0) 3472 bp->b_flags |= B_CACHE; 3473 3474 if (newbsize < bp->b_bufsize) { 3475 /* 3476 * DEV_BSIZE aligned new buffer size is less then the 3477 * DEV_BSIZE aligned existing buffer size. Figure out 3478 * if we have to remove any pages. 3479 */ 3480 if (desiredpages < bp->b_npages) { 3481 vm_page_t m; 3482 3483 if (buf_mapped(bp)) { 3484 BUF_CHECK_MAPPED(bp); 3485 pmap_qremove((vm_offset_t)trunc_page( 3486 (vm_offset_t)bp->b_data) + 3487 (desiredpages << PAGE_SHIFT), 3488 (bp->b_npages - desiredpages)); 3489 } else 3490 BUF_CHECK_UNMAPPED(bp); 3491 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 3492 for (i = desiredpages; i < bp->b_npages; i++) { 3493 /* 3494 * the page is not freed here -- it 3495 * is the responsibility of 3496 * vnode_pager_setsize 3497 */ 3498 m = bp->b_pages[i]; 3499 KASSERT(m != bogus_page, 3500 ("allocbuf: bogus page found")); 3501 while (vm_page_sleep_if_busy(m, 3502 "biodep")) 3503 continue; 3504 3505 bp->b_pages[i] = NULL; 3506 vm_page_lock(m); 3507 vm_page_unwire(m, PQ_INACTIVE); 3508 vm_page_unlock(m); 3509 } 3510 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 3511 bp->b_npages = desiredpages; 3512 } 3513 } else if (size > bp->b_bcount) { 3514 /* 3515 * We are growing the buffer, possibly in a 3516 * byte-granular fashion. 3517 */ 3518 vm_object_t obj; 3519 vm_offset_t toff; 3520 vm_offset_t tinc; 3521 3522 /* 3523 * Step 1, bring in the VM pages from the object, 3524 * allocating them if necessary. We must clear 3525 * B_CACHE if these pages are not valid for the 3526 * range covered by the buffer. 3527 */ 3528 3529 obj = bp->b_bufobj->bo_object; 3530 3531 VM_OBJECT_WLOCK(obj); 3532 while (bp->b_npages < desiredpages) { 3533 vm_page_t m; 3534 3535 /* 3536 * We must allocate system pages since blocking 3537 * here could interfere with paging I/O, no 3538 * matter which process we are. 3539 * 3540 * Only exclusive busy can be tested here. 3541 * Blocking on shared busy might lead to 3542 * deadlocks once allocbuf() is called after 3543 * pages are vfs_busy_pages(). 3544 */ 3545 m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) + 3546 bp->b_npages, VM_ALLOC_NOBUSY | 3547 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED | 3548 VM_ALLOC_IGN_SBUSY | 3549 VM_ALLOC_COUNT(desiredpages - bp->b_npages)); 3550 if (m->valid == 0) 3551 bp->b_flags &= ~B_CACHE; 3552 bp->b_pages[bp->b_npages] = m; 3553 ++bp->b_npages; 3554 } 3555 3556 /* 3557 * Step 2. We've loaded the pages into the buffer, 3558 * we have to figure out if we can still have B_CACHE 3559 * set. Note that B_CACHE is set according to the 3560 * byte-granular range ( bcount and size ), new the 3561 * aligned range ( newbsize ). 3562 * 3563 * The VM test is against m->valid, which is DEV_BSIZE 3564 * aligned. Needless to say, the validity of the data 3565 * needs to also be DEV_BSIZE aligned. Note that this 3566 * fails with NFS if the server or some other client 3567 * extends the file's EOF. If our buffer is resized, 3568 * B_CACHE may remain set! XXX 3569 */ 3570 3571 toff = bp->b_bcount; 3572 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 3573 3574 while ((bp->b_flags & B_CACHE) && toff < size) { 3575 vm_pindex_t pi; 3576 3577 if (tinc > (size - toff)) 3578 tinc = size - toff; 3579 3580 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 3581 PAGE_SHIFT; 3582 3583 vfs_buf_test_cache( 3584 bp, 3585 bp->b_offset, 3586 toff, 3587 tinc, 3588 bp->b_pages[pi] 3589 ); 3590 toff += tinc; 3591 tinc = PAGE_SIZE; 3592 } 3593 VM_OBJECT_WUNLOCK(obj); 3594 3595 /* 3596 * Step 3, fixup the KVA pmap. 3597 */ 3598 if (buf_mapped(bp)) 3599 bpmap_qenter(bp); 3600 else 3601 BUF_CHECK_UNMAPPED(bp); 3602 } 3603 } 3604 /* Record changes in allocation size. */ 3605 if (bp->b_bufsize != newbsize) 3606 bufspaceadjust(bp, newbsize); 3607 bp->b_bcount = size; /* requested buffer size. */ 3608 return 1; 3609 } 3610 3611 extern int inflight_transient_maps; 3612 3613 void 3614 biodone(struct bio *bp) 3615 { 3616 struct mtx *mtxp; 3617 void (*done)(struct bio *); 3618 vm_offset_t start, end; 3619 3620 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) { 3621 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING; 3622 bp->bio_flags |= BIO_UNMAPPED; 3623 start = trunc_page((vm_offset_t)bp->bio_data); 3624 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length); 3625 bp->bio_data = unmapped_buf; 3626 pmap_qremove(start, OFF_TO_IDX(end - start)); 3627 vmem_free(transient_arena, start, end - start); 3628 atomic_add_int(&inflight_transient_maps, -1); 3629 } 3630 done = bp->bio_done; 3631 if (done == NULL) { 3632 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3633 mtx_lock(mtxp); 3634 bp->bio_flags |= BIO_DONE; 3635 wakeup(bp); 3636 mtx_unlock(mtxp); 3637 } else { 3638 bp->bio_flags |= BIO_DONE; 3639 done(bp); 3640 } 3641 } 3642 3643 /* 3644 * Wait for a BIO to finish. 3645 */ 3646 int 3647 biowait(struct bio *bp, const char *wchan) 3648 { 3649 struct mtx *mtxp; 3650 3651 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3652 mtx_lock(mtxp); 3653 while ((bp->bio_flags & BIO_DONE) == 0) 3654 msleep(bp, mtxp, PRIBIO, wchan, 0); 3655 mtx_unlock(mtxp); 3656 if (bp->bio_error != 0) 3657 return (bp->bio_error); 3658 if (!(bp->bio_flags & BIO_ERROR)) 3659 return (0); 3660 return (EIO); 3661 } 3662 3663 void 3664 biofinish(struct bio *bp, struct devstat *stat, int error) 3665 { 3666 3667 if (error) { 3668 bp->bio_error = error; 3669 bp->bio_flags |= BIO_ERROR; 3670 } 3671 if (stat != NULL) 3672 devstat_end_transaction_bio(stat, bp); 3673 biodone(bp); 3674 } 3675 3676 /* 3677 * bufwait: 3678 * 3679 * Wait for buffer I/O completion, returning error status. The buffer 3680 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3681 * error and cleared. 3682 */ 3683 int 3684 bufwait(struct buf *bp) 3685 { 3686 if (bp->b_iocmd == BIO_READ) 3687 bwait(bp, PRIBIO, "biord"); 3688 else 3689 bwait(bp, PRIBIO, "biowr"); 3690 if (bp->b_flags & B_EINTR) { 3691 bp->b_flags &= ~B_EINTR; 3692 return (EINTR); 3693 } 3694 if (bp->b_ioflags & BIO_ERROR) { 3695 return (bp->b_error ? bp->b_error : EIO); 3696 } else { 3697 return (0); 3698 } 3699 } 3700 3701 /* 3702 * Call back function from struct bio back up to struct buf. 3703 */ 3704 static void 3705 bufdonebio(struct bio *bip) 3706 { 3707 struct buf *bp; 3708 3709 bp = bip->bio_caller2; 3710 bp->b_resid = bip->bio_resid; 3711 bp->b_ioflags = bip->bio_flags; 3712 bp->b_error = bip->bio_error; 3713 if (bp->b_error) 3714 bp->b_ioflags |= BIO_ERROR; 3715 bufdone(bp); 3716 g_destroy_bio(bip); 3717 } 3718 3719 void 3720 dev_strategy(struct cdev *dev, struct buf *bp) 3721 { 3722 struct cdevsw *csw; 3723 int ref; 3724 3725 KASSERT(dev->si_refcount > 0, 3726 ("dev_strategy on un-referenced struct cdev *(%s) %p", 3727 devtoname(dev), dev)); 3728 3729 csw = dev_refthread(dev, &ref); 3730 dev_strategy_csw(dev, csw, bp); 3731 dev_relthread(dev, ref); 3732 } 3733 3734 void 3735 dev_strategy_csw(struct cdev *dev, struct cdevsw *csw, struct buf *bp) 3736 { 3737 struct bio *bip; 3738 3739 KASSERT(bp->b_iocmd == BIO_READ || bp->b_iocmd == BIO_WRITE, 3740 ("b_iocmd botch")); 3741 KASSERT(((dev->si_flags & SI_ETERNAL) != 0 && csw != NULL) || 3742 dev->si_threadcount > 0, 3743 ("dev_strategy_csw threadcount cdev *(%s) %p", devtoname(dev), 3744 dev)); 3745 if (csw == NULL) { 3746 bp->b_error = ENXIO; 3747 bp->b_ioflags = BIO_ERROR; 3748 bufdone(bp); 3749 return; 3750 } 3751 for (;;) { 3752 bip = g_new_bio(); 3753 if (bip != NULL) 3754 break; 3755 /* Try again later */ 3756 tsleep(&bp, PRIBIO, "dev_strat", hz/10); 3757 } 3758 bip->bio_cmd = bp->b_iocmd; 3759 bip->bio_offset = bp->b_iooffset; 3760 bip->bio_length = bp->b_bcount; 3761 bip->bio_bcount = bp->b_bcount; /* XXX: remove */ 3762 bdata2bio(bp, bip); 3763 bip->bio_done = bufdonebio; 3764 bip->bio_caller2 = bp; 3765 bip->bio_dev = dev; 3766 (*csw->d_strategy)(bip); 3767 } 3768 3769 /* 3770 * bufdone: 3771 * 3772 * Finish I/O on a buffer, optionally calling a completion function. 3773 * This is usually called from an interrupt so process blocking is 3774 * not allowed. 3775 * 3776 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3777 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3778 * assuming B_INVAL is clear. 3779 * 3780 * For the VMIO case, we set B_CACHE if the op was a read and no 3781 * read error occured, or if the op was a write. B_CACHE is never 3782 * set if the buffer is invalid or otherwise uncacheable. 3783 * 3784 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3785 * initiator to leave B_INVAL set to brelse the buffer out of existance 3786 * in the biodone routine. 3787 */ 3788 void 3789 bufdone(struct buf *bp) 3790 { 3791 struct bufobj *dropobj; 3792 void (*biodone)(struct buf *); 3793 3794 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 3795 dropobj = NULL; 3796 3797 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 3798 BUF_ASSERT_HELD(bp); 3799 3800 runningbufwakeup(bp); 3801 if (bp->b_iocmd == BIO_WRITE) 3802 dropobj = bp->b_bufobj; 3803 /* call optional completion function if requested */ 3804 if (bp->b_iodone != NULL) { 3805 biodone = bp->b_iodone; 3806 bp->b_iodone = NULL; 3807 (*biodone) (bp); 3808 if (dropobj) 3809 bufobj_wdrop(dropobj); 3810 return; 3811 } 3812 3813 bufdone_finish(bp); 3814 3815 if (dropobj) 3816 bufobj_wdrop(dropobj); 3817 } 3818 3819 void 3820 bufdone_finish(struct buf *bp) 3821 { 3822 BUF_ASSERT_HELD(bp); 3823 3824 if (!LIST_EMPTY(&bp->b_dep)) 3825 buf_complete(bp); 3826 3827 if (bp->b_flags & B_VMIO) { 3828 vm_ooffset_t foff; 3829 vm_page_t m; 3830 vm_object_t obj; 3831 struct vnode *vp; 3832 int bogus, i, iosize; 3833 3834 obj = bp->b_bufobj->bo_object; 3835 KASSERT(obj->paging_in_progress >= bp->b_npages, 3836 ("biodone_finish: paging in progress(%d) < b_npages(%d)", 3837 obj->paging_in_progress, bp->b_npages)); 3838 3839 vp = bp->b_vp; 3840 KASSERT(vp->v_holdcnt > 0, 3841 ("biodone_finish: vnode %p has zero hold count", vp)); 3842 KASSERT(vp->v_object != NULL, 3843 ("biodone_finish: vnode %p has no vm_object", vp)); 3844 3845 foff = bp->b_offset; 3846 KASSERT(bp->b_offset != NOOFFSET, 3847 ("biodone_finish: bp %p has no buffer offset", bp)); 3848 3849 /* 3850 * Set B_CACHE if the op was a normal read and no error 3851 * occured. B_CACHE is set for writes in the b*write() 3852 * routines. 3853 */ 3854 iosize = bp->b_bcount - bp->b_resid; 3855 if (bp->b_iocmd == BIO_READ && 3856 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 3857 !(bp->b_ioflags & BIO_ERROR)) { 3858 bp->b_flags |= B_CACHE; 3859 } 3860 bogus = 0; 3861 VM_OBJECT_WLOCK(obj); 3862 for (i = 0; i < bp->b_npages; i++) { 3863 int bogusflag = 0; 3864 int resid; 3865 3866 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 3867 if (resid > iosize) 3868 resid = iosize; 3869 3870 /* 3871 * cleanup bogus pages, restoring the originals 3872 */ 3873 m = bp->b_pages[i]; 3874 if (m == bogus_page) { 3875 bogus = bogusflag = 1; 3876 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3877 if (m == NULL) 3878 panic("biodone: page disappeared!"); 3879 bp->b_pages[i] = m; 3880 } 3881 KASSERT(OFF_TO_IDX(foff) == m->pindex, 3882 ("biodone_finish: foff(%jd)/pindex(%ju) mismatch", 3883 (intmax_t)foff, (uintmax_t)m->pindex)); 3884 3885 /* 3886 * In the write case, the valid and clean bits are 3887 * already changed correctly ( see bdwrite() ), so we 3888 * only need to do this here in the read case. 3889 */ 3890 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 3891 KASSERT((m->dirty & vm_page_bits(foff & 3892 PAGE_MASK, resid)) == 0, ("bufdone_finish:" 3893 " page %p has unexpected dirty bits", m)); 3894 vfs_page_set_valid(bp, foff, m); 3895 } 3896 3897 vm_page_sunbusy(m); 3898 vm_object_pip_subtract(obj, 1); 3899 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3900 iosize -= resid; 3901 } 3902 vm_object_pip_wakeupn(obj, 0); 3903 VM_OBJECT_WUNLOCK(obj); 3904 if (bogus && buf_mapped(bp)) { 3905 BUF_CHECK_MAPPED(bp); 3906 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3907 bp->b_pages, bp->b_npages); 3908 } 3909 } 3910 3911 /* 3912 * For asynchronous completions, release the buffer now. The brelse 3913 * will do a wakeup there if necessary - so no need to do a wakeup 3914 * here in the async case. The sync case always needs to do a wakeup. 3915 */ 3916 3917 if (bp->b_flags & B_ASYNC) { 3918 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 3919 brelse(bp); 3920 else 3921 bqrelse(bp); 3922 } else 3923 bdone(bp); 3924 } 3925 3926 /* 3927 * This routine is called in lieu of iodone in the case of 3928 * incomplete I/O. This keeps the busy status for pages 3929 * consistant. 3930 */ 3931 void 3932 vfs_unbusy_pages(struct buf *bp) 3933 { 3934 int i; 3935 vm_object_t obj; 3936 vm_page_t m; 3937 3938 runningbufwakeup(bp); 3939 if (!(bp->b_flags & B_VMIO)) 3940 return; 3941 3942 obj = bp->b_bufobj->bo_object; 3943 VM_OBJECT_WLOCK(obj); 3944 for (i = 0; i < bp->b_npages; i++) { 3945 m = bp->b_pages[i]; 3946 if (m == bogus_page) { 3947 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 3948 if (!m) 3949 panic("vfs_unbusy_pages: page missing\n"); 3950 bp->b_pages[i] = m; 3951 if (buf_mapped(bp)) { 3952 BUF_CHECK_MAPPED(bp); 3953 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3954 bp->b_pages, bp->b_npages); 3955 } else 3956 BUF_CHECK_UNMAPPED(bp); 3957 } 3958 vm_object_pip_subtract(obj, 1); 3959 vm_page_sunbusy(m); 3960 } 3961 vm_object_pip_wakeupn(obj, 0); 3962 VM_OBJECT_WUNLOCK(obj); 3963 } 3964 3965 /* 3966 * vfs_page_set_valid: 3967 * 3968 * Set the valid bits in a page based on the supplied offset. The 3969 * range is restricted to the buffer's size. 3970 * 3971 * This routine is typically called after a read completes. 3972 */ 3973 static void 3974 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3975 { 3976 vm_ooffset_t eoff; 3977 3978 /* 3979 * Compute the end offset, eoff, such that [off, eoff) does not span a 3980 * page boundary and eoff is not greater than the end of the buffer. 3981 * The end of the buffer, in this case, is our file EOF, not the 3982 * allocation size of the buffer. 3983 */ 3984 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 3985 if (eoff > bp->b_offset + bp->b_bcount) 3986 eoff = bp->b_offset + bp->b_bcount; 3987 3988 /* 3989 * Set valid range. This is typically the entire buffer and thus the 3990 * entire page. 3991 */ 3992 if (eoff > off) 3993 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off); 3994 } 3995 3996 /* 3997 * vfs_page_set_validclean: 3998 * 3999 * Set the valid bits and clear the dirty bits in a page based on the 4000 * supplied offset. The range is restricted to the buffer's size. 4001 */ 4002 static void 4003 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4004 { 4005 vm_ooffset_t soff, eoff; 4006 4007 /* 4008 * Start and end offsets in buffer. eoff - soff may not cross a 4009 * page boundry or cross the end of the buffer. The end of the 4010 * buffer, in this case, is our file EOF, not the allocation size 4011 * of the buffer. 4012 */ 4013 soff = off; 4014 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4015 if (eoff > bp->b_offset + bp->b_bcount) 4016 eoff = bp->b_offset + bp->b_bcount; 4017 4018 /* 4019 * Set valid range. This is typically the entire buffer and thus the 4020 * entire page. 4021 */ 4022 if (eoff > soff) { 4023 vm_page_set_validclean( 4024 m, 4025 (vm_offset_t) (soff & PAGE_MASK), 4026 (vm_offset_t) (eoff - soff) 4027 ); 4028 } 4029 } 4030 4031 /* 4032 * Ensure that all buffer pages are not exclusive busied. If any page is 4033 * exclusive busy, drain it. 4034 */ 4035 void 4036 vfs_drain_busy_pages(struct buf *bp) 4037 { 4038 vm_page_t m; 4039 int i, last_busied; 4040 4041 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object); 4042 last_busied = 0; 4043 for (i = 0; i < bp->b_npages; i++) { 4044 m = bp->b_pages[i]; 4045 if (vm_page_xbusied(m)) { 4046 for (; last_busied < i; last_busied++) 4047 vm_page_sbusy(bp->b_pages[last_busied]); 4048 while (vm_page_xbusied(m)) { 4049 vm_page_lock(m); 4050 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4051 vm_page_busy_sleep(m, "vbpage"); 4052 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4053 } 4054 } 4055 } 4056 for (i = 0; i < last_busied; i++) 4057 vm_page_sunbusy(bp->b_pages[i]); 4058 } 4059 4060 /* 4061 * This routine is called before a device strategy routine. 4062 * It is used to tell the VM system that paging I/O is in 4063 * progress, and treat the pages associated with the buffer 4064 * almost as being exclusive busy. Also the object paging_in_progress 4065 * flag is handled to make sure that the object doesn't become 4066 * inconsistant. 4067 * 4068 * Since I/O has not been initiated yet, certain buffer flags 4069 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 4070 * and should be ignored. 4071 */ 4072 void 4073 vfs_busy_pages(struct buf *bp, int clear_modify) 4074 { 4075 int i, bogus; 4076 vm_object_t obj; 4077 vm_ooffset_t foff; 4078 vm_page_t m; 4079 4080 if (!(bp->b_flags & B_VMIO)) 4081 return; 4082 4083 obj = bp->b_bufobj->bo_object; 4084 foff = bp->b_offset; 4085 KASSERT(bp->b_offset != NOOFFSET, 4086 ("vfs_busy_pages: no buffer offset")); 4087 VM_OBJECT_WLOCK(obj); 4088 vfs_drain_busy_pages(bp); 4089 if (bp->b_bufsize != 0) 4090 vfs_setdirty_locked_object(bp); 4091 bogus = 0; 4092 for (i = 0; i < bp->b_npages; i++) { 4093 m = bp->b_pages[i]; 4094 4095 if ((bp->b_flags & B_CLUSTER) == 0) { 4096 vm_object_pip_add(obj, 1); 4097 vm_page_sbusy(m); 4098 } 4099 /* 4100 * When readying a buffer for a read ( i.e 4101 * clear_modify == 0 ), it is important to do 4102 * bogus_page replacement for valid pages in 4103 * partially instantiated buffers. Partially 4104 * instantiated buffers can, in turn, occur when 4105 * reconstituting a buffer from its VM backing store 4106 * base. We only have to do this if B_CACHE is 4107 * clear ( which causes the I/O to occur in the 4108 * first place ). The replacement prevents the read 4109 * I/O from overwriting potentially dirty VM-backed 4110 * pages. XXX bogus page replacement is, uh, bogus. 4111 * It may not work properly with small-block devices. 4112 * We need to find a better way. 4113 */ 4114 if (clear_modify) { 4115 pmap_remove_write(m); 4116 vfs_page_set_validclean(bp, foff, m); 4117 } else if (m->valid == VM_PAGE_BITS_ALL && 4118 (bp->b_flags & B_CACHE) == 0) { 4119 bp->b_pages[i] = bogus_page; 4120 bogus++; 4121 } 4122 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4123 } 4124 VM_OBJECT_WUNLOCK(obj); 4125 if (bogus && buf_mapped(bp)) { 4126 BUF_CHECK_MAPPED(bp); 4127 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4128 bp->b_pages, bp->b_npages); 4129 } 4130 } 4131 4132 /* 4133 * vfs_bio_set_valid: 4134 * 4135 * Set the range within the buffer to valid. The range is 4136 * relative to the beginning of the buffer, b_offset. Note that 4137 * b_offset itself may be offset from the beginning of the first 4138 * page. 4139 */ 4140 void 4141 vfs_bio_set_valid(struct buf *bp, int base, int size) 4142 { 4143 int i, n; 4144 vm_page_t m; 4145 4146 if (!(bp->b_flags & B_VMIO)) 4147 return; 4148 4149 /* 4150 * Fixup base to be relative to beginning of first page. 4151 * Set initial n to be the maximum number of bytes in the 4152 * first page that can be validated. 4153 */ 4154 base += (bp->b_offset & PAGE_MASK); 4155 n = PAGE_SIZE - (base & PAGE_MASK); 4156 4157 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4158 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4159 m = bp->b_pages[i]; 4160 if (n > size) 4161 n = size; 4162 vm_page_set_valid_range(m, base & PAGE_MASK, n); 4163 base += n; 4164 size -= n; 4165 n = PAGE_SIZE; 4166 } 4167 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4168 } 4169 4170 /* 4171 * vfs_bio_clrbuf: 4172 * 4173 * If the specified buffer is a non-VMIO buffer, clear the entire 4174 * buffer. If the specified buffer is a VMIO buffer, clear and 4175 * validate only the previously invalid portions of the buffer. 4176 * This routine essentially fakes an I/O, so we need to clear 4177 * BIO_ERROR and B_INVAL. 4178 * 4179 * Note that while we only theoretically need to clear through b_bcount, 4180 * we go ahead and clear through b_bufsize. 4181 */ 4182 void 4183 vfs_bio_clrbuf(struct buf *bp) 4184 { 4185 int i, j, mask, sa, ea, slide; 4186 4187 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 4188 clrbuf(bp); 4189 return; 4190 } 4191 bp->b_flags &= ~B_INVAL; 4192 bp->b_ioflags &= ~BIO_ERROR; 4193 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4194 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 4195 (bp->b_offset & PAGE_MASK) == 0) { 4196 if (bp->b_pages[0] == bogus_page) 4197 goto unlock; 4198 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 4199 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object); 4200 if ((bp->b_pages[0]->valid & mask) == mask) 4201 goto unlock; 4202 if ((bp->b_pages[0]->valid & mask) == 0) { 4203 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize); 4204 bp->b_pages[0]->valid |= mask; 4205 goto unlock; 4206 } 4207 } 4208 sa = bp->b_offset & PAGE_MASK; 4209 slide = 0; 4210 for (i = 0; i < bp->b_npages; i++, sa = 0) { 4211 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize); 4212 ea = slide & PAGE_MASK; 4213 if (ea == 0) 4214 ea = PAGE_SIZE; 4215 if (bp->b_pages[i] == bogus_page) 4216 continue; 4217 j = sa / DEV_BSIZE; 4218 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 4219 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object); 4220 if ((bp->b_pages[i]->valid & mask) == mask) 4221 continue; 4222 if ((bp->b_pages[i]->valid & mask) == 0) 4223 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa); 4224 else { 4225 for (; sa < ea; sa += DEV_BSIZE, j++) { 4226 if ((bp->b_pages[i]->valid & (1 << j)) == 0) { 4227 pmap_zero_page_area(bp->b_pages[i], 4228 sa, DEV_BSIZE); 4229 } 4230 } 4231 } 4232 bp->b_pages[i]->valid |= mask; 4233 } 4234 unlock: 4235 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4236 bp->b_resid = 0; 4237 } 4238 4239 void 4240 vfs_bio_bzero_buf(struct buf *bp, int base, int size) 4241 { 4242 vm_page_t m; 4243 int i, n; 4244 4245 if (buf_mapped(bp)) { 4246 BUF_CHECK_MAPPED(bp); 4247 bzero(bp->b_data + base, size); 4248 } else { 4249 BUF_CHECK_UNMAPPED(bp); 4250 n = PAGE_SIZE - (base & PAGE_MASK); 4251 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4252 m = bp->b_pages[i]; 4253 if (n > size) 4254 n = size; 4255 pmap_zero_page_area(m, base & PAGE_MASK, n); 4256 base += n; 4257 size -= n; 4258 n = PAGE_SIZE; 4259 } 4260 } 4261 } 4262 4263 /* 4264 * vm_hold_load_pages and vm_hold_free_pages get pages into 4265 * a buffers address space. The pages are anonymous and are 4266 * not associated with a file object. 4267 */ 4268 static void 4269 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4270 { 4271 vm_offset_t pg; 4272 vm_page_t p; 4273 int index; 4274 4275 BUF_CHECK_MAPPED(bp); 4276 4277 to = round_page(to); 4278 from = round_page(from); 4279 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4280 4281 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 4282 tryagain: 4283 /* 4284 * note: must allocate system pages since blocking here 4285 * could interfere with paging I/O, no matter which 4286 * process we are. 4287 */ 4288 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ | 4289 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT)); 4290 if (p == NULL) { 4291 VM_WAIT; 4292 goto tryagain; 4293 } 4294 pmap_qenter(pg, &p, 1); 4295 bp->b_pages[index] = p; 4296 } 4297 bp->b_npages = index; 4298 } 4299 4300 /* Return pages associated with this buf to the vm system */ 4301 static void 4302 vm_hold_free_pages(struct buf *bp, int newbsize) 4303 { 4304 vm_offset_t from; 4305 vm_page_t p; 4306 int index, newnpages; 4307 4308 BUF_CHECK_MAPPED(bp); 4309 4310 from = round_page((vm_offset_t)bp->b_data + newbsize); 4311 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4312 if (bp->b_npages > newnpages) 4313 pmap_qremove(from, bp->b_npages - newnpages); 4314 for (index = newnpages; index < bp->b_npages; index++) { 4315 p = bp->b_pages[index]; 4316 bp->b_pages[index] = NULL; 4317 if (vm_page_sbusied(p)) 4318 printf("vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 4319 (intmax_t)bp->b_blkno, (intmax_t)bp->b_lblkno); 4320 p->wire_count--; 4321 vm_page_free(p); 4322 atomic_subtract_int(&vm_cnt.v_wire_count, 1); 4323 } 4324 bp->b_npages = newnpages; 4325 } 4326 4327 /* 4328 * Map an IO request into kernel virtual address space. 4329 * 4330 * All requests are (re)mapped into kernel VA space. 4331 * Notice that we use b_bufsize for the size of the buffer 4332 * to be mapped. b_bcount might be modified by the driver. 4333 * 4334 * Note that even if the caller determines that the address space should 4335 * be valid, a race or a smaller-file mapped into a larger space may 4336 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 4337 * check the return value. 4338 * 4339 * This function only works with pager buffers. 4340 */ 4341 int 4342 vmapbuf(struct buf *bp, int mapbuf) 4343 { 4344 vm_prot_t prot; 4345 int pidx; 4346 4347 if (bp->b_bufsize < 0) 4348 return (-1); 4349 prot = VM_PROT_READ; 4350 if (bp->b_iocmd == BIO_READ) 4351 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 4352 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 4353 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages, 4354 btoc(MAXPHYS))) < 0) 4355 return (-1); 4356 bp->b_npages = pidx; 4357 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK; 4358 if (mapbuf || !unmapped_buf_allowed) { 4359 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_pages, pidx); 4360 bp->b_data = bp->b_kvabase + bp->b_offset; 4361 } else 4362 bp->b_data = unmapped_buf; 4363 return(0); 4364 } 4365 4366 /* 4367 * Free the io map PTEs associated with this IO operation. 4368 * We also invalidate the TLB entries and restore the original b_addr. 4369 * 4370 * This function only works with pager buffers. 4371 */ 4372 void 4373 vunmapbuf(struct buf *bp) 4374 { 4375 int npages; 4376 4377 npages = bp->b_npages; 4378 if (buf_mapped(bp)) 4379 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 4380 vm_page_unhold_pages(bp->b_pages, npages); 4381 4382 bp->b_data = unmapped_buf; 4383 } 4384 4385 void 4386 bdone(struct buf *bp) 4387 { 4388 struct mtx *mtxp; 4389 4390 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4391 mtx_lock(mtxp); 4392 bp->b_flags |= B_DONE; 4393 wakeup(bp); 4394 mtx_unlock(mtxp); 4395 } 4396 4397 void 4398 bwait(struct buf *bp, u_char pri, const char *wchan) 4399 { 4400 struct mtx *mtxp; 4401 4402 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4403 mtx_lock(mtxp); 4404 while ((bp->b_flags & B_DONE) == 0) 4405 msleep(bp, mtxp, pri, wchan, 0); 4406 mtx_unlock(mtxp); 4407 } 4408 4409 int 4410 bufsync(struct bufobj *bo, int waitfor) 4411 { 4412 4413 return (VOP_FSYNC(bo->__bo_vnode, waitfor, curthread)); 4414 } 4415 4416 void 4417 bufstrategy(struct bufobj *bo, struct buf *bp) 4418 { 4419 int i = 0; 4420 struct vnode *vp; 4421 4422 vp = bp->b_vp; 4423 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 4424 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 4425 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 4426 i = VOP_STRATEGY(vp, bp); 4427 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 4428 } 4429 4430 void 4431 bufobj_wrefl(struct bufobj *bo) 4432 { 4433 4434 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4435 ASSERT_BO_WLOCKED(bo); 4436 bo->bo_numoutput++; 4437 } 4438 4439 void 4440 bufobj_wref(struct bufobj *bo) 4441 { 4442 4443 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4444 BO_LOCK(bo); 4445 bo->bo_numoutput++; 4446 BO_UNLOCK(bo); 4447 } 4448 4449 void 4450 bufobj_wdrop(struct bufobj *bo) 4451 { 4452 4453 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 4454 BO_LOCK(bo); 4455 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 4456 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 4457 bo->bo_flag &= ~BO_WWAIT; 4458 wakeup(&bo->bo_numoutput); 4459 } 4460 BO_UNLOCK(bo); 4461 } 4462 4463 int 4464 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 4465 { 4466 int error; 4467 4468 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 4469 ASSERT_BO_WLOCKED(bo); 4470 error = 0; 4471 while (bo->bo_numoutput) { 4472 bo->bo_flag |= BO_WWAIT; 4473 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo), 4474 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 4475 if (error) 4476 break; 4477 } 4478 return (error); 4479 } 4480 4481 void 4482 bpin(struct buf *bp) 4483 { 4484 struct mtx *mtxp; 4485 4486 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4487 mtx_lock(mtxp); 4488 bp->b_pin_count++; 4489 mtx_unlock(mtxp); 4490 } 4491 4492 void 4493 bunpin(struct buf *bp) 4494 { 4495 struct mtx *mtxp; 4496 4497 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4498 mtx_lock(mtxp); 4499 if (--bp->b_pin_count == 0) 4500 wakeup(bp); 4501 mtx_unlock(mtxp); 4502 } 4503 4504 void 4505 bunpin_wait(struct buf *bp) 4506 { 4507 struct mtx *mtxp; 4508 4509 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4510 mtx_lock(mtxp); 4511 while (bp->b_pin_count > 0) 4512 msleep(bp, mtxp, PRIBIO, "bwunpin", 0); 4513 mtx_unlock(mtxp); 4514 } 4515 4516 /* 4517 * Set bio_data or bio_ma for struct bio from the struct buf. 4518 */ 4519 void 4520 bdata2bio(struct buf *bp, struct bio *bip) 4521 { 4522 4523 if (!buf_mapped(bp)) { 4524 KASSERT(unmapped_buf_allowed, ("unmapped")); 4525 bip->bio_ma = bp->b_pages; 4526 bip->bio_ma_n = bp->b_npages; 4527 bip->bio_data = unmapped_buf; 4528 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 4529 bip->bio_flags |= BIO_UNMAPPED; 4530 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) / 4531 PAGE_SIZE == bp->b_npages, 4532 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset, 4533 (long long)bip->bio_length, bip->bio_ma_n)); 4534 } else { 4535 bip->bio_data = bp->b_data; 4536 bip->bio_ma = NULL; 4537 } 4538 } 4539 4540 #include "opt_ddb.h" 4541 #ifdef DDB 4542 #include <ddb/ddb.h> 4543 4544 /* DDB command to show buffer data */ 4545 DB_SHOW_COMMAND(buffer, db_show_buffer) 4546 { 4547 /* get args */ 4548 struct buf *bp = (struct buf *)addr; 4549 4550 if (!have_addr) { 4551 db_printf("usage: show buffer <addr>\n"); 4552 return; 4553 } 4554 4555 db_printf("buf at %p\n", bp); 4556 db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n", 4557 (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags, 4558 PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS); 4559 db_printf( 4560 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 4561 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, " 4562 "b_dep = %p\n", 4563 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 4564 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 4565 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first); 4566 db_printf("b_kvabase = %p, b_kvasize = %d\n", 4567 bp->b_kvabase, bp->b_kvasize); 4568 if (bp->b_npages) { 4569 int i; 4570 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 4571 for (i = 0; i < bp->b_npages; i++) { 4572 vm_page_t m; 4573 m = bp->b_pages[i]; 4574 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 4575 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 4576 if ((i + 1) < bp->b_npages) 4577 db_printf(","); 4578 } 4579 db_printf("\n"); 4580 } 4581 db_printf(" "); 4582 BUF_LOCKPRINTINFO(bp); 4583 } 4584 4585 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 4586 { 4587 struct buf *bp; 4588 int i; 4589 4590 for (i = 0; i < nbuf; i++) { 4591 bp = &buf[i]; 4592 if (BUF_ISLOCKED(bp)) { 4593 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4594 db_printf("\n"); 4595 } 4596 } 4597 } 4598 4599 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 4600 { 4601 struct vnode *vp; 4602 struct buf *bp; 4603 4604 if (!have_addr) { 4605 db_printf("usage: show vnodebufs <addr>\n"); 4606 return; 4607 } 4608 vp = (struct vnode *)addr; 4609 db_printf("Clean buffers:\n"); 4610 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 4611 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4612 db_printf("\n"); 4613 } 4614 db_printf("Dirty buffers:\n"); 4615 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 4616 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4617 db_printf("\n"); 4618 } 4619 } 4620 4621 DB_COMMAND(countfreebufs, db_coundfreebufs) 4622 { 4623 struct buf *bp; 4624 int i, used = 0, nfree = 0; 4625 4626 if (have_addr) { 4627 db_printf("usage: countfreebufs\n"); 4628 return; 4629 } 4630 4631 for (i = 0; i < nbuf; i++) { 4632 bp = &buf[i]; 4633 if ((bp->b_flags & B_INFREECNT) != 0) 4634 nfree++; 4635 else 4636 used++; 4637 } 4638 4639 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 4640 nfree + used); 4641 db_printf("numfreebuffers is %d\n", numfreebuffers); 4642 } 4643 #endif /* DDB */ 4644