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 static struct proc *bufdaemonproc; 102 103 static int inmem(struct vnode *vp, daddr_t blkno); 104 static void vm_hold_free_pages(struct buf *bp, int newbsize); 105 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from, 106 vm_offset_t to); 107 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m); 108 static void vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, 109 vm_page_t m); 110 static void vfs_clean_pages_dirty_buf(struct buf *bp); 111 static void vfs_setdirty_locked_object(struct buf *bp); 112 static void vfs_vmio_release(struct buf *bp); 113 static int vfs_bio_clcheck(struct vnode *vp, int size, 114 daddr_t lblkno, daddr_t blkno); 115 static int buf_flush(int); 116 static int flushbufqueues(int, int); 117 static void buf_daemon(void); 118 static void bremfreel(struct buf *bp); 119 static __inline void bd_wakeup(void); 120 static int sysctl_runningspace(SYSCTL_HANDLER_ARGS); 121 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 122 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 123 static int sysctl_bufspace(SYSCTL_HANDLER_ARGS); 124 #endif 125 126 int vmiodirenable = TRUE; 127 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, 128 "Use the VM system for directory writes"); 129 long runningbufspace; 130 SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 131 "Amount of presently outstanding async buffer io"); 132 static long bufspace; 133 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 134 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 135 SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD, 136 &bufspace, 0, sysctl_bufspace, "L", "Virtual memory used for buffers"); 137 #else 138 SYSCTL_LONG(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, 139 "Virtual memory used for buffers"); 140 #endif 141 static long unmapped_bufspace; 142 SYSCTL_LONG(_vfs, OID_AUTO, unmapped_bufspace, CTLFLAG_RD, 143 &unmapped_bufspace, 0, 144 "Amount of unmapped buffers, inclusive in the bufspace"); 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 */ 456 457 static __inline void 458 bufspacewakeup(void) 459 { 460 int need_wakeup, on; 461 462 /* 463 * If someone is waiting for BUF space, wake them up. Even 464 * though we haven't freed the kva space yet, the waiting 465 * process will be able to now. 466 */ 467 rw_rlock(&nblock); 468 for (;;) { 469 need_wakeup = 0; 470 on = needsbuffer; 471 if ((on & VFS_BIO_NEED_BUFSPACE) == 0) 472 break; 473 need_wakeup = 1; 474 if (atomic_cmpset_rel_int(&needsbuffer, on, 475 on & ~VFS_BIO_NEED_BUFSPACE)) 476 break; 477 } 478 if (need_wakeup) 479 wakeup(__DEVOLATILE(void *, &needsbuffer)); 480 rw_runlock(&nblock); 481 } 482 483 /* 484 * runningwakeup: 485 * 486 * Wake up processes that are waiting on asynchronous writes to fall 487 * below lorunningspace. 488 */ 489 static void 490 runningwakeup(void) 491 { 492 493 mtx_lock(&rbreqlock); 494 if (runningbufreq) { 495 runningbufreq = 0; 496 wakeup(&runningbufreq); 497 } 498 mtx_unlock(&rbreqlock); 499 } 500 501 /* 502 * runningbufwakeup: 503 * 504 * Decrement the outstanding write count according. 505 */ 506 void 507 runningbufwakeup(struct buf *bp) 508 { 509 long space, bspace; 510 511 bspace = bp->b_runningbufspace; 512 if (bspace == 0) 513 return; 514 space = atomic_fetchadd_long(&runningbufspace, -bspace); 515 KASSERT(space >= bspace, ("runningbufspace underflow %ld %ld", 516 space, bspace)); 517 bp->b_runningbufspace = 0; 518 /* 519 * Only acquire the lock and wakeup on the transition from exceeding 520 * the threshold to falling below it. 521 */ 522 if (space < lorunningspace) 523 return; 524 if (space - bspace > lorunningspace) 525 return; 526 runningwakeup(); 527 } 528 529 /* 530 * bufcountadd: 531 * 532 * Called when a buffer has been added to one of the free queues to 533 * account for the buffer and to wakeup anyone waiting for free buffers. 534 * This typically occurs when large amounts of metadata are being handled 535 * by the buffer cache ( else buffer space runs out first, usually ). 536 */ 537 static __inline void 538 bufcountadd(struct buf *bp) 539 { 540 int mask, need_wakeup, old, on; 541 542 KASSERT((bp->b_flags & B_INFREECNT) == 0, 543 ("buf %p already counted as free", bp)); 544 bp->b_flags |= B_INFREECNT; 545 old = atomic_fetchadd_int(&numfreebuffers, 1); 546 KASSERT(old >= 0 && old < nbuf, 547 ("numfreebuffers climbed to %d", old + 1)); 548 mask = VFS_BIO_NEED_ANY; 549 if (numfreebuffers >= hifreebuffers) 550 mask |= VFS_BIO_NEED_FREE; 551 rw_rlock(&nblock); 552 for (;;) { 553 need_wakeup = 0; 554 on = needsbuffer; 555 if (on == 0) 556 break; 557 need_wakeup = 1; 558 if (atomic_cmpset_rel_int(&needsbuffer, on, on & ~mask)) 559 break; 560 } 561 if (need_wakeup) 562 wakeup(__DEVOLATILE(void *, &needsbuffer)); 563 rw_runlock(&nblock); 564 } 565 566 /* 567 * bufcountsub: 568 * 569 * Decrement the numfreebuffers count as needed. 570 */ 571 static void 572 bufcountsub(struct buf *bp) 573 { 574 int old; 575 576 /* 577 * Fixup numfreebuffers count. If the buffer is invalid or not 578 * delayed-write, the buffer was free and we must decrement 579 * numfreebuffers. 580 */ 581 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { 582 KASSERT((bp->b_flags & B_INFREECNT) != 0, 583 ("buf %p not counted in numfreebuffers", bp)); 584 bp->b_flags &= ~B_INFREECNT; 585 old = atomic_fetchadd_int(&numfreebuffers, -1); 586 KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1)); 587 } 588 } 589 590 /* 591 * waitrunningbufspace() 592 * 593 * runningbufspace is a measure of the amount of I/O currently 594 * running. This routine is used in async-write situations to 595 * prevent creating huge backups of pending writes to a device. 596 * Only asynchronous writes are governed by this function. 597 * 598 * This does NOT turn an async write into a sync write. It waits 599 * for earlier writes to complete and generally returns before the 600 * caller's write has reached the device. 601 */ 602 void 603 waitrunningbufspace(void) 604 { 605 606 mtx_lock(&rbreqlock); 607 while (runningbufspace > hirunningspace) { 608 runningbufreq = 1; 609 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 610 } 611 mtx_unlock(&rbreqlock); 612 } 613 614 615 /* 616 * vfs_buf_test_cache: 617 * 618 * Called when a buffer is extended. This function clears the B_CACHE 619 * bit if the newly extended portion of the buffer does not contain 620 * valid data. 621 */ 622 static __inline 623 void 624 vfs_buf_test_cache(struct buf *bp, 625 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 626 vm_page_t m) 627 { 628 629 VM_OBJECT_ASSERT_LOCKED(m->object); 630 if (bp->b_flags & B_CACHE) { 631 int base = (foff + off) & PAGE_MASK; 632 if (vm_page_is_valid(m, base, size) == 0) 633 bp->b_flags &= ~B_CACHE; 634 } 635 } 636 637 /* Wake up the buffer daemon if necessary */ 638 static __inline void 639 bd_wakeup(void) 640 { 641 642 mtx_lock(&bdlock); 643 if (bd_request == 0) { 644 bd_request = 1; 645 wakeup(&bd_request); 646 } 647 mtx_unlock(&bdlock); 648 } 649 650 /* 651 * bd_speedup - speedup the buffer cache flushing code 652 */ 653 void 654 bd_speedup(void) 655 { 656 int needwake; 657 658 mtx_lock(&bdlock); 659 needwake = 0; 660 if (bd_speedupreq == 0 || bd_request == 0) 661 needwake = 1; 662 bd_speedupreq = 1; 663 bd_request = 1; 664 if (needwake) 665 wakeup(&bd_request); 666 mtx_unlock(&bdlock); 667 } 668 669 #ifdef __i386__ 670 #define TRANSIENT_DENOM 5 671 #else 672 #define TRANSIENT_DENOM 10 673 #endif 674 675 /* 676 * Calculating buffer cache scaling values and reserve space for buffer 677 * headers. This is called during low level kernel initialization and 678 * may be called more then once. We CANNOT write to the memory area 679 * being reserved at this time. 680 */ 681 caddr_t 682 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 683 { 684 int tuned_nbuf; 685 long maxbuf, maxbuf_sz, buf_sz, biotmap_sz; 686 687 /* 688 * physmem_est is in pages. Convert it to kilobytes (assumes 689 * PAGE_SIZE is >= 1K) 690 */ 691 physmem_est = physmem_est * (PAGE_SIZE / 1024); 692 693 /* 694 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 695 * For the first 64MB of ram nominally allocate sufficient buffers to 696 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 697 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing 698 * the buffer cache we limit the eventual kva reservation to 699 * maxbcache bytes. 700 * 701 * factor represents the 1/4 x ram conversion. 702 */ 703 if (nbuf == 0) { 704 int factor = 4 * BKVASIZE / 1024; 705 706 nbuf = 50; 707 if (physmem_est > 4096) 708 nbuf += min((physmem_est - 4096) / factor, 709 65536 / factor); 710 if (physmem_est > 65536) 711 nbuf += min((physmem_est - 65536) * 2 / (factor * 5), 712 32 * 1024 * 1024 / (factor * 5)); 713 714 if (maxbcache && nbuf > maxbcache / BKVASIZE) 715 nbuf = maxbcache / BKVASIZE; 716 tuned_nbuf = 1; 717 } else 718 tuned_nbuf = 0; 719 720 /* XXX Avoid unsigned long overflows later on with maxbufspace. */ 721 maxbuf = (LONG_MAX / 3) / BKVASIZE; 722 if (nbuf > maxbuf) { 723 if (!tuned_nbuf) 724 printf("Warning: nbufs lowered from %d to %ld\n", nbuf, 725 maxbuf); 726 nbuf = maxbuf; 727 } 728 729 /* 730 * Ideal allocation size for the transient bio submap is 10% 731 * of the maximal space buffer map. This roughly corresponds 732 * to the amount of the buffer mapped for typical UFS load. 733 * 734 * Clip the buffer map to reserve space for the transient 735 * BIOs, if its extent is bigger than 90% (80% on i386) of the 736 * maximum buffer map extent on the platform. 737 * 738 * The fall-back to the maxbuf in case of maxbcache unset, 739 * allows to not trim the buffer KVA for the architectures 740 * with ample KVA space. 741 */ 742 if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) { 743 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE; 744 buf_sz = (long)nbuf * BKVASIZE; 745 if (buf_sz < maxbuf_sz / TRANSIENT_DENOM * 746 (TRANSIENT_DENOM - 1)) { 747 /* 748 * There is more KVA than memory. Do not 749 * adjust buffer map size, and assign the rest 750 * of maxbuf to transient map. 751 */ 752 biotmap_sz = maxbuf_sz - buf_sz; 753 } else { 754 /* 755 * Buffer map spans all KVA we could afford on 756 * this platform. Give 10% (20% on i386) of 757 * the buffer map to the transient bio map. 758 */ 759 biotmap_sz = buf_sz / TRANSIENT_DENOM; 760 buf_sz -= biotmap_sz; 761 } 762 if (biotmap_sz / INT_MAX > MAXPHYS) 763 bio_transient_maxcnt = INT_MAX; 764 else 765 bio_transient_maxcnt = biotmap_sz / MAXPHYS; 766 /* 767 * Artifically limit to 1024 simultaneous in-flight I/Os 768 * using the transient mapping. 769 */ 770 if (bio_transient_maxcnt > 1024) 771 bio_transient_maxcnt = 1024; 772 if (tuned_nbuf) 773 nbuf = buf_sz / BKVASIZE; 774 } 775 776 /* 777 * swbufs are used as temporary holders for I/O, such as paging I/O. 778 * We have no less then 16 and no more then 256. 779 */ 780 nswbuf = max(min(nbuf/4, 256), 16); 781 #ifdef NSWBUF_MIN 782 if (nswbuf < NSWBUF_MIN) 783 nswbuf = NSWBUF_MIN; 784 #endif 785 786 /* 787 * Reserve space for the buffer cache buffers 788 */ 789 swbuf = (void *)v; 790 v = (caddr_t)(swbuf + nswbuf); 791 buf = (void *)v; 792 v = (caddr_t)(buf + nbuf); 793 794 return(v); 795 } 796 797 /* Initialize the buffer subsystem. Called before use of any buffers. */ 798 void 799 bufinit(void) 800 { 801 struct buf *bp; 802 int i; 803 804 mtx_init(&bqclean, "bufq clean lock", NULL, MTX_DEF); 805 mtx_init(&bqdirty, "bufq dirty lock", NULL, MTX_DEF); 806 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 807 rw_init(&nblock, "needsbuffer lock"); 808 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 809 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF); 810 811 /* next, make a null set of free lists */ 812 for (i = 0; i < BUFFER_QUEUES; i++) 813 TAILQ_INIT(&bufqueues[i]); 814 815 /* finally, initialize each buffer header and stick on empty q */ 816 for (i = 0; i < nbuf; i++) { 817 bp = &buf[i]; 818 bzero(bp, sizeof *bp); 819 bp->b_flags = B_INVAL | B_INFREECNT; 820 bp->b_rcred = NOCRED; 821 bp->b_wcred = NOCRED; 822 bp->b_qindex = QUEUE_EMPTY; 823 bp->b_xflags = 0; 824 LIST_INIT(&bp->b_dep); 825 BUF_LOCKINIT(bp); 826 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 827 #ifdef INVARIANTS 828 bq_len[QUEUE_EMPTY]++; 829 #endif 830 } 831 832 /* 833 * maxbufspace is the absolute maximum amount of buffer space we are 834 * allowed to reserve in KVM and in real terms. The absolute maximum 835 * is nominally used by buf_daemon. hibufspace is the nominal maximum 836 * used by most other processes. The differential is required to 837 * ensure that buf_daemon is able to run when other processes might 838 * be blocked waiting for buffer space. 839 * 840 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 841 * this may result in KVM fragmentation which is not handled optimally 842 * by the system. 843 */ 844 maxbufspace = (long)nbuf * BKVASIZE; 845 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 846 lobufspace = hibufspace - MAXBSIZE; 847 848 /* 849 * Note: The 16 MiB upper limit for hirunningspace was chosen 850 * arbitrarily and may need further tuning. It corresponds to 851 * 128 outstanding write IO requests (if IO size is 128 KiB), 852 * which fits with many RAID controllers' tagged queuing limits. 853 * The lower 1 MiB limit is the historical upper limit for 854 * hirunningspace. 855 */ 856 hirunningspace = lmax(lmin(roundup(hibufspace / 64, MAXBSIZE), 857 16 * 1024 * 1024), 1024 * 1024); 858 lorunningspace = roundup((hirunningspace * 2) / 3, MAXBSIZE); 859 860 /* 861 * Limit the amount of malloc memory since it is wired permanently into 862 * the kernel space. Even though this is accounted for in the buffer 863 * allocation, we don't want the malloced region to grow uncontrolled. 864 * The malloc scheme improves memory utilization significantly on average 865 * (small) directories. 866 */ 867 maxbufmallocspace = hibufspace / 20; 868 869 /* 870 * Reduce the chance of a deadlock occuring by limiting the number 871 * of delayed-write dirty buffers we allow to stack up. 872 */ 873 hidirtybuffers = nbuf / 4 + 20; 874 dirtybufthresh = hidirtybuffers * 9 / 10; 875 numdirtybuffers = 0; 876 /* 877 * To support extreme low-memory systems, make sure hidirtybuffers cannot 878 * eat up all available buffer space. This occurs when our minimum cannot 879 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 880 * BKVASIZE'd buffers. 881 */ 882 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 883 hidirtybuffers >>= 1; 884 } 885 lodirtybuffers = hidirtybuffers / 2; 886 887 /* 888 * Try to keep the number of free buffers in the specified range, 889 * and give special processes (e.g. like buf_daemon) access to an 890 * emergency reserve. 891 */ 892 lofreebuffers = nbuf / 18 + 5; 893 hifreebuffers = 2 * lofreebuffers; 894 numfreebuffers = nbuf; 895 896 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ | 897 VM_ALLOC_NORMAL | VM_ALLOC_WIRED); 898 unmapped_buf = (caddr_t)kva_alloc(MAXPHYS); 899 } 900 901 #ifdef INVARIANTS 902 static inline void 903 vfs_buf_check_mapped(struct buf *bp) 904 { 905 906 KASSERT((bp->b_flags & B_UNMAPPED) == 0, 907 ("mapped buf %p %x", bp, bp->b_flags)); 908 KASSERT(bp->b_kvabase != unmapped_buf, 909 ("mapped buf: b_kvabase was not updated %p", bp)); 910 KASSERT(bp->b_data != unmapped_buf, 911 ("mapped buf: b_data was not updated %p", bp)); 912 } 913 914 static inline void 915 vfs_buf_check_unmapped(struct buf *bp) 916 { 917 918 KASSERT((bp->b_flags & B_UNMAPPED) == B_UNMAPPED, 919 ("unmapped buf %p %x", bp, bp->b_flags)); 920 KASSERT(bp->b_kvabase == unmapped_buf, 921 ("unmapped buf: corrupted b_kvabase %p", bp)); 922 KASSERT(bp->b_data == unmapped_buf, 923 ("unmapped buf: corrupted b_data %p", bp)); 924 } 925 926 #define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp) 927 #define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp) 928 #else 929 #define BUF_CHECK_MAPPED(bp) do {} while (0) 930 #define BUF_CHECK_UNMAPPED(bp) do {} while (0) 931 #endif 932 933 static void 934 bpmap_qenter(struct buf *bp) 935 { 936 937 BUF_CHECK_MAPPED(bp); 938 939 /* 940 * bp->b_data is relative to bp->b_offset, but 941 * bp->b_offset may be offset into the first page. 942 */ 943 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data); 944 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages); 945 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 946 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 947 } 948 949 /* 950 * bfreekva() - free the kva allocation for a buffer. 951 * 952 * Since this call frees up buffer space, we call bufspacewakeup(). 953 */ 954 static void 955 bfreekva(struct buf *bp) 956 { 957 958 if (bp->b_kvasize == 0) 959 return; 960 961 atomic_add_int(&buffreekvacnt, 1); 962 atomic_subtract_long(&bufspace, bp->b_kvasize); 963 if ((bp->b_flags & B_UNMAPPED) == 0) { 964 BUF_CHECK_MAPPED(bp); 965 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, 966 bp->b_kvasize); 967 } else { 968 BUF_CHECK_UNMAPPED(bp); 969 if ((bp->b_flags & B_KVAALLOC) != 0) { 970 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvaalloc, 971 bp->b_kvasize); 972 } 973 atomic_subtract_long(&unmapped_bufspace, bp->b_kvasize); 974 bp->b_flags &= ~(B_UNMAPPED | B_KVAALLOC); 975 } 976 bp->b_kvasize = 0; 977 bufspacewakeup(); 978 } 979 980 /* 981 * binsfree: 982 * 983 * Insert the buffer into the appropriate free list. 984 */ 985 static void 986 binsfree(struct buf *bp, int qindex) 987 { 988 struct mtx *olock, *nlock; 989 990 BUF_ASSERT_XLOCKED(bp); 991 992 olock = bqlock(bp->b_qindex); 993 nlock = bqlock(qindex); 994 mtx_lock(olock); 995 /* Handle delayed bremfree() processing. */ 996 if (bp->b_flags & B_REMFREE) 997 bremfreel(bp); 998 999 if (bp->b_qindex != QUEUE_NONE) 1000 panic("binsfree: free buffer onto another queue???"); 1001 1002 bp->b_qindex = qindex; 1003 if (olock != nlock) { 1004 mtx_unlock(olock); 1005 mtx_lock(nlock); 1006 } 1007 if (bp->b_flags & B_AGE) 1008 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1009 else 1010 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1011 #ifdef INVARIANTS 1012 bq_len[bp->b_qindex]++; 1013 #endif 1014 mtx_unlock(nlock); 1015 1016 /* 1017 * Something we can maybe free or reuse. 1018 */ 1019 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1020 bufspacewakeup(); 1021 1022 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI)) 1023 bufcountadd(bp); 1024 } 1025 1026 /* 1027 * bremfree: 1028 * 1029 * Mark the buffer for removal from the appropriate free list. 1030 * 1031 */ 1032 void 1033 bremfree(struct buf *bp) 1034 { 1035 1036 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1037 KASSERT((bp->b_flags & B_REMFREE) == 0, 1038 ("bremfree: buffer %p already marked for delayed removal.", bp)); 1039 KASSERT(bp->b_qindex != QUEUE_NONE, 1040 ("bremfree: buffer %p not on a queue.", bp)); 1041 BUF_ASSERT_XLOCKED(bp); 1042 1043 bp->b_flags |= B_REMFREE; 1044 bufcountsub(bp); 1045 } 1046 1047 /* 1048 * bremfreef: 1049 * 1050 * Force an immediate removal from a free list. Used only in nfs when 1051 * it abuses the b_freelist pointer. 1052 */ 1053 void 1054 bremfreef(struct buf *bp) 1055 { 1056 struct mtx *qlock; 1057 1058 qlock = bqlock(bp->b_qindex); 1059 mtx_lock(qlock); 1060 bremfreel(bp); 1061 mtx_unlock(qlock); 1062 } 1063 1064 /* 1065 * bremfreel: 1066 * 1067 * Removes a buffer from the free list, must be called with the 1068 * correct qlock held. 1069 */ 1070 static void 1071 bremfreel(struct buf *bp) 1072 { 1073 1074 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X", 1075 bp, bp->b_vp, bp->b_flags); 1076 KASSERT(bp->b_qindex != QUEUE_NONE, 1077 ("bremfreel: buffer %p not on a queue.", bp)); 1078 BUF_ASSERT_XLOCKED(bp); 1079 mtx_assert(bqlock(bp->b_qindex), MA_OWNED); 1080 1081 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 1082 #ifdef INVARIANTS 1083 KASSERT(bq_len[bp->b_qindex] >= 1, ("queue %d underflow", 1084 bp->b_qindex)); 1085 bq_len[bp->b_qindex]--; 1086 #endif 1087 bp->b_qindex = QUEUE_NONE; 1088 /* 1089 * If this was a delayed bremfree() we only need to remove the buffer 1090 * from the queue and return the stats are already done. 1091 */ 1092 if (bp->b_flags & B_REMFREE) { 1093 bp->b_flags &= ~B_REMFREE; 1094 return; 1095 } 1096 bufcountsub(bp); 1097 } 1098 1099 /* 1100 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 1101 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 1102 * the buffer is valid and we do not have to do anything. 1103 */ 1104 void 1105 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, 1106 int cnt, struct ucred * cred) 1107 { 1108 struct buf *rabp; 1109 int i; 1110 1111 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 1112 if (inmem(vp, *rablkno)) 1113 continue; 1114 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 1115 1116 if ((rabp->b_flags & B_CACHE) == 0) { 1117 if (!TD_IS_IDLETHREAD(curthread)) 1118 curthread->td_ru.ru_inblock++; 1119 rabp->b_flags |= B_ASYNC; 1120 rabp->b_flags &= ~B_INVAL; 1121 rabp->b_ioflags &= ~BIO_ERROR; 1122 rabp->b_iocmd = BIO_READ; 1123 if (rabp->b_rcred == NOCRED && cred != NOCRED) 1124 rabp->b_rcred = crhold(cred); 1125 vfs_busy_pages(rabp, 0); 1126 BUF_KERNPROC(rabp); 1127 rabp->b_iooffset = dbtob(rabp->b_blkno); 1128 bstrategy(rabp); 1129 } else { 1130 brelse(rabp); 1131 } 1132 } 1133 } 1134 1135 /* 1136 * Entry point for bread() and breadn() via #defines in sys/buf.h. 1137 * 1138 * Get a buffer with the specified data. Look in the cache first. We 1139 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 1140 * is set, the buffer is valid and we do not have to do anything, see 1141 * getblk(). Also starts asynchronous I/O on read-ahead blocks. 1142 */ 1143 int 1144 breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno, 1145 int *rabsize, int cnt, struct ucred *cred, int flags, struct buf **bpp) 1146 { 1147 struct buf *bp; 1148 int rv = 0, readwait = 0; 1149 1150 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 1151 /* 1152 * Can only return NULL if GB_LOCK_NOWAIT flag is specified. 1153 */ 1154 *bpp = bp = getblk(vp, blkno, size, 0, 0, flags); 1155 if (bp == NULL) 1156 return (EBUSY); 1157 1158 /* if not found in cache, do some I/O */ 1159 if ((bp->b_flags & B_CACHE) == 0) { 1160 if (!TD_IS_IDLETHREAD(curthread)) 1161 curthread->td_ru.ru_inblock++; 1162 bp->b_iocmd = BIO_READ; 1163 bp->b_flags &= ~B_INVAL; 1164 bp->b_ioflags &= ~BIO_ERROR; 1165 if (bp->b_rcred == NOCRED && cred != NOCRED) 1166 bp->b_rcred = crhold(cred); 1167 vfs_busy_pages(bp, 0); 1168 bp->b_iooffset = dbtob(bp->b_blkno); 1169 bstrategy(bp); 1170 ++readwait; 1171 } 1172 1173 breada(vp, rablkno, rabsize, cnt, cred); 1174 1175 if (readwait) { 1176 rv = bufwait(bp); 1177 } 1178 return (rv); 1179 } 1180 1181 /* 1182 * Write, release buffer on completion. (Done by iodone 1183 * if async). Do not bother writing anything if the buffer 1184 * is invalid. 1185 * 1186 * Note that we set B_CACHE here, indicating that buffer is 1187 * fully valid and thus cacheable. This is true even of NFS 1188 * now so we set it generally. This could be set either here 1189 * or in biodone() since the I/O is synchronous. We put it 1190 * here. 1191 */ 1192 int 1193 bufwrite(struct buf *bp) 1194 { 1195 int oldflags; 1196 struct vnode *vp; 1197 long space; 1198 int vp_md; 1199 1200 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1201 if (bp->b_flags & B_INVAL) { 1202 brelse(bp); 1203 return (0); 1204 } 1205 1206 if (bp->b_flags & B_BARRIER) 1207 barrierwrites++; 1208 1209 oldflags = bp->b_flags; 1210 1211 BUF_ASSERT_HELD(bp); 1212 1213 if (bp->b_pin_count > 0) 1214 bunpin_wait(bp); 1215 1216 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 1217 ("FFS background buffer should not get here %p", bp)); 1218 1219 vp = bp->b_vp; 1220 if (vp) 1221 vp_md = vp->v_vflag & VV_MD; 1222 else 1223 vp_md = 0; 1224 1225 /* 1226 * Mark the buffer clean. Increment the bufobj write count 1227 * before bundirty() call, to prevent other thread from seeing 1228 * empty dirty list and zero counter for writes in progress, 1229 * falsely indicating that the bufobj is clean. 1230 */ 1231 bufobj_wref(bp->b_bufobj); 1232 bundirty(bp); 1233 1234 bp->b_flags &= ~B_DONE; 1235 bp->b_ioflags &= ~BIO_ERROR; 1236 bp->b_flags |= B_CACHE; 1237 bp->b_iocmd = BIO_WRITE; 1238 1239 vfs_busy_pages(bp, 1); 1240 1241 /* 1242 * Normal bwrites pipeline writes 1243 */ 1244 bp->b_runningbufspace = bp->b_bufsize; 1245 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace); 1246 1247 if (!TD_IS_IDLETHREAD(curthread)) 1248 curthread->td_ru.ru_oublock++; 1249 if (oldflags & B_ASYNC) 1250 BUF_KERNPROC(bp); 1251 bp->b_iooffset = dbtob(bp->b_blkno); 1252 bstrategy(bp); 1253 1254 if ((oldflags & B_ASYNC) == 0) { 1255 int rtval = bufwait(bp); 1256 brelse(bp); 1257 return (rtval); 1258 } else if (space > hirunningspace) { 1259 /* 1260 * don't allow the async write to saturate the I/O 1261 * system. We will not deadlock here because 1262 * we are blocking waiting for I/O that is already in-progress 1263 * to complete. We do not block here if it is the update 1264 * or syncer daemon trying to clean up as that can lead 1265 * to deadlock. 1266 */ 1267 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 1268 waitrunningbufspace(); 1269 } 1270 1271 return (0); 1272 } 1273 1274 void 1275 bufbdflush(struct bufobj *bo, struct buf *bp) 1276 { 1277 struct buf *nbp; 1278 1279 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 1280 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 1281 altbufferflushes++; 1282 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 1283 BO_LOCK(bo); 1284 /* 1285 * Try to find a buffer to flush. 1286 */ 1287 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 1288 if ((nbp->b_vflags & BV_BKGRDINPROG) || 1289 BUF_LOCK(nbp, 1290 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 1291 continue; 1292 if (bp == nbp) 1293 panic("bdwrite: found ourselves"); 1294 BO_UNLOCK(bo); 1295 /* Don't countdeps with the bo lock held. */ 1296 if (buf_countdeps(nbp, 0)) { 1297 BO_LOCK(bo); 1298 BUF_UNLOCK(nbp); 1299 continue; 1300 } 1301 if (nbp->b_flags & B_CLUSTEROK) { 1302 vfs_bio_awrite(nbp); 1303 } else { 1304 bremfree(nbp); 1305 bawrite(nbp); 1306 } 1307 dirtybufferflushes++; 1308 break; 1309 } 1310 if (nbp == NULL) 1311 BO_UNLOCK(bo); 1312 } 1313 } 1314 1315 /* 1316 * Delayed write. (Buffer is marked dirty). Do not bother writing 1317 * anything if the buffer is marked invalid. 1318 * 1319 * Note that since the buffer must be completely valid, we can safely 1320 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 1321 * biodone() in order to prevent getblk from writing the buffer 1322 * out synchronously. 1323 */ 1324 void 1325 bdwrite(struct buf *bp) 1326 { 1327 struct thread *td = curthread; 1328 struct vnode *vp; 1329 struct bufobj *bo; 1330 1331 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1332 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1333 KASSERT((bp->b_flags & B_BARRIER) == 0, 1334 ("Barrier request in delayed write %p", bp)); 1335 BUF_ASSERT_HELD(bp); 1336 1337 if (bp->b_flags & B_INVAL) { 1338 brelse(bp); 1339 return; 1340 } 1341 1342 /* 1343 * If we have too many dirty buffers, don't create any more. 1344 * If we are wildly over our limit, then force a complete 1345 * cleanup. Otherwise, just keep the situation from getting 1346 * out of control. Note that we have to avoid a recursive 1347 * disaster and not try to clean up after our own cleanup! 1348 */ 1349 vp = bp->b_vp; 1350 bo = bp->b_bufobj; 1351 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 1352 td->td_pflags |= TDP_INBDFLUSH; 1353 BO_BDFLUSH(bo, bp); 1354 td->td_pflags &= ~TDP_INBDFLUSH; 1355 } else 1356 recursiveflushes++; 1357 1358 bdirty(bp); 1359 /* 1360 * Set B_CACHE, indicating that the buffer is fully valid. This is 1361 * true even of NFS now. 1362 */ 1363 bp->b_flags |= B_CACHE; 1364 1365 /* 1366 * This bmap keeps the system from needing to do the bmap later, 1367 * perhaps when the system is attempting to do a sync. Since it 1368 * is likely that the indirect block -- or whatever other datastructure 1369 * that the filesystem needs is still in memory now, it is a good 1370 * thing to do this. Note also, that if the pageout daemon is 1371 * requesting a sync -- there might not be enough memory to do 1372 * the bmap then... So, this is important to do. 1373 */ 1374 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 1375 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 1376 } 1377 1378 /* 1379 * Set the *dirty* buffer range based upon the VM system dirty 1380 * pages. 1381 * 1382 * Mark the buffer pages as clean. We need to do this here to 1383 * satisfy the vnode_pager and the pageout daemon, so that it 1384 * thinks that the pages have been "cleaned". Note that since 1385 * the pages are in a delayed write buffer -- the VFS layer 1386 * "will" see that the pages get written out on the next sync, 1387 * or perhaps the cluster will be completed. 1388 */ 1389 vfs_clean_pages_dirty_buf(bp); 1390 bqrelse(bp); 1391 1392 /* 1393 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 1394 * due to the softdep code. 1395 */ 1396 } 1397 1398 /* 1399 * bdirty: 1400 * 1401 * Turn buffer into delayed write request. We must clear BIO_READ and 1402 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 1403 * itself to properly update it in the dirty/clean lists. We mark it 1404 * B_DONE to ensure that any asynchronization of the buffer properly 1405 * clears B_DONE ( else a panic will occur later ). 1406 * 1407 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 1408 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 1409 * should only be called if the buffer is known-good. 1410 * 1411 * Since the buffer is not on a queue, we do not update the numfreebuffers 1412 * count. 1413 * 1414 * The buffer must be on QUEUE_NONE. 1415 */ 1416 void 1417 bdirty(struct buf *bp) 1418 { 1419 1420 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 1421 bp, bp->b_vp, bp->b_flags); 1422 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1423 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1424 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1425 BUF_ASSERT_HELD(bp); 1426 bp->b_flags &= ~(B_RELBUF); 1427 bp->b_iocmd = BIO_WRITE; 1428 1429 if ((bp->b_flags & B_DELWRI) == 0) { 1430 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 1431 reassignbuf(bp); 1432 bdirtyadd(); 1433 } 1434 } 1435 1436 /* 1437 * bundirty: 1438 * 1439 * Clear B_DELWRI for buffer. 1440 * 1441 * Since the buffer is not on a queue, we do not update the numfreebuffers 1442 * count. 1443 * 1444 * The buffer must be on QUEUE_NONE. 1445 */ 1446 1447 void 1448 bundirty(struct buf *bp) 1449 { 1450 1451 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1452 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1453 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1454 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1455 BUF_ASSERT_HELD(bp); 1456 1457 if (bp->b_flags & B_DELWRI) { 1458 bp->b_flags &= ~B_DELWRI; 1459 reassignbuf(bp); 1460 bdirtysub(); 1461 } 1462 /* 1463 * Since it is now being written, we can clear its deferred write flag. 1464 */ 1465 bp->b_flags &= ~B_DEFERRED; 1466 } 1467 1468 /* 1469 * bawrite: 1470 * 1471 * Asynchronous write. Start output on a buffer, but do not wait for 1472 * it to complete. The buffer is released when the output completes. 1473 * 1474 * bwrite() ( or the VOP routine anyway ) is responsible for handling 1475 * B_INVAL buffers. Not us. 1476 */ 1477 void 1478 bawrite(struct buf *bp) 1479 { 1480 1481 bp->b_flags |= B_ASYNC; 1482 (void) bwrite(bp); 1483 } 1484 1485 /* 1486 * babarrierwrite: 1487 * 1488 * Asynchronous barrier write. Start output on a buffer, but do not 1489 * wait for it to complete. Place a write barrier after this write so 1490 * that this buffer and all buffers written before it are committed to 1491 * the disk before any buffers written after this write are committed 1492 * to the disk. The buffer is released when the output completes. 1493 */ 1494 void 1495 babarrierwrite(struct buf *bp) 1496 { 1497 1498 bp->b_flags |= B_ASYNC | B_BARRIER; 1499 (void) bwrite(bp); 1500 } 1501 1502 /* 1503 * bbarrierwrite: 1504 * 1505 * Synchronous barrier write. Start output on a buffer and wait for 1506 * it to complete. Place a write barrier after this write so that 1507 * this buffer and all buffers written before it are committed to 1508 * the disk before any buffers written after this write are committed 1509 * to the disk. The buffer is released when the output completes. 1510 */ 1511 int 1512 bbarrierwrite(struct buf *bp) 1513 { 1514 1515 bp->b_flags |= B_BARRIER; 1516 return (bwrite(bp)); 1517 } 1518 1519 /* 1520 * bwillwrite: 1521 * 1522 * Called prior to the locking of any vnodes when we are expecting to 1523 * write. We do not want to starve the buffer cache with too many 1524 * dirty buffers so we block here. By blocking prior to the locking 1525 * of any vnodes we attempt to avoid the situation where a locked vnode 1526 * prevents the various system daemons from flushing related buffers. 1527 */ 1528 void 1529 bwillwrite(void) 1530 { 1531 1532 if (numdirtybuffers >= hidirtybuffers) { 1533 mtx_lock(&bdirtylock); 1534 while (numdirtybuffers >= hidirtybuffers) { 1535 bdirtywait = 1; 1536 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4), 1537 "flswai", 0); 1538 } 1539 mtx_unlock(&bdirtylock); 1540 } 1541 } 1542 1543 /* 1544 * Return true if we have too many dirty buffers. 1545 */ 1546 int 1547 buf_dirty_count_severe(void) 1548 { 1549 1550 return(numdirtybuffers >= hidirtybuffers); 1551 } 1552 1553 static __noinline int 1554 buf_vm_page_count_severe(void) 1555 { 1556 1557 KFAIL_POINT_CODE(DEBUG_FP, buf_pressure, return 1); 1558 1559 return vm_page_count_severe(); 1560 } 1561 1562 /* 1563 * brelse: 1564 * 1565 * Release a busy buffer and, if requested, free its resources. The 1566 * buffer will be stashed in the appropriate bufqueue[] allowing it 1567 * to be accessed later as a cache entity or reused for other purposes. 1568 */ 1569 void 1570 brelse(struct buf *bp) 1571 { 1572 int qindex; 1573 1574 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 1575 bp, bp->b_vp, bp->b_flags); 1576 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1577 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1578 1579 if (BUF_LOCKRECURSED(bp)) { 1580 /* 1581 * Do not process, in particular, do not handle the 1582 * B_INVAL/B_RELBUF and do not release to free list. 1583 */ 1584 BUF_UNLOCK(bp); 1585 return; 1586 } 1587 1588 if (bp->b_flags & B_MANAGED) { 1589 bqrelse(bp); 1590 return; 1591 } 1592 1593 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 1594 bp->b_error == EIO && !(bp->b_flags & B_INVAL)) { 1595 /* 1596 * Failed write, redirty. Must clear BIO_ERROR to prevent 1597 * pages from being scrapped. If the error is anything 1598 * other than an I/O error (EIO), assume that retrying 1599 * is futile. 1600 */ 1601 bp->b_ioflags &= ~BIO_ERROR; 1602 bdirty(bp); 1603 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 1604 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 1605 /* 1606 * Either a failed I/O or we were asked to free or not 1607 * cache the buffer. 1608 */ 1609 bp->b_flags |= B_INVAL; 1610 if (!LIST_EMPTY(&bp->b_dep)) 1611 buf_deallocate(bp); 1612 if (bp->b_flags & B_DELWRI) 1613 bdirtysub(); 1614 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1615 if ((bp->b_flags & B_VMIO) == 0) { 1616 if (bp->b_bufsize) 1617 allocbuf(bp, 0); 1618 if (bp->b_vp) 1619 brelvp(bp); 1620 } 1621 } 1622 1623 /* 1624 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1625 * is called with B_DELWRI set, the underlying pages may wind up 1626 * getting freed causing a previous write (bdwrite()) to get 'lost' 1627 * because pages associated with a B_DELWRI bp are marked clean. 1628 * 1629 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1630 * if B_DELWRI is set. 1631 * 1632 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1633 * on pages to return pages to the VM page queues. 1634 */ 1635 if (bp->b_flags & B_DELWRI) 1636 bp->b_flags &= ~B_RELBUF; 1637 else if (buf_vm_page_count_severe()) { 1638 /* 1639 * BKGRDINPROG can only be set with the buf and bufobj 1640 * locks both held. We tolerate a race to clear it here. 1641 */ 1642 if (!(bp->b_vflags & BV_BKGRDINPROG)) 1643 bp->b_flags |= B_RELBUF; 1644 } 1645 1646 /* 1647 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1648 * constituted, not even NFS buffers now. Two flags effect this. If 1649 * B_INVAL, the struct buf is invalidated but the VM object is kept 1650 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1651 * 1652 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 1653 * invalidated. BIO_ERROR cannot be set for a failed write unless the 1654 * buffer is also B_INVAL because it hits the re-dirtying code above. 1655 * 1656 * Normally we can do this whether a buffer is B_DELWRI or not. If 1657 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1658 * the commit state and we cannot afford to lose the buffer. If the 1659 * buffer has a background write in progress, we need to keep it 1660 * around to prevent it from being reconstituted and starting a second 1661 * background write. 1662 */ 1663 if ((bp->b_flags & B_VMIO) 1664 && !(bp->b_vp->v_mount != NULL && 1665 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 1666 !vn_isdisk(bp->b_vp, NULL) && 1667 (bp->b_flags & B_DELWRI)) 1668 ) { 1669 1670 int i, j, resid; 1671 vm_page_t m; 1672 off_t foff; 1673 vm_pindex_t poff; 1674 vm_object_t obj; 1675 1676 obj = bp->b_bufobj->bo_object; 1677 1678 /* 1679 * Get the base offset and length of the buffer. Note that 1680 * in the VMIO case if the buffer block size is not 1681 * page-aligned then b_data pointer may not be page-aligned. 1682 * But our b_pages[] array *IS* page aligned. 1683 * 1684 * block sizes less then DEV_BSIZE (usually 512) are not 1685 * supported due to the page granularity bits (m->valid, 1686 * m->dirty, etc...). 1687 * 1688 * See man buf(9) for more information 1689 */ 1690 resid = bp->b_bufsize; 1691 foff = bp->b_offset; 1692 for (i = 0; i < bp->b_npages; i++) { 1693 int had_bogus = 0; 1694 1695 m = bp->b_pages[i]; 1696 1697 /* 1698 * If we hit a bogus page, fixup *all* the bogus pages 1699 * now. 1700 */ 1701 if (m == bogus_page) { 1702 poff = OFF_TO_IDX(bp->b_offset); 1703 had_bogus = 1; 1704 1705 VM_OBJECT_RLOCK(obj); 1706 for (j = i; j < bp->b_npages; j++) { 1707 vm_page_t mtmp; 1708 mtmp = bp->b_pages[j]; 1709 if (mtmp == bogus_page) { 1710 mtmp = vm_page_lookup(obj, poff + j); 1711 if (!mtmp) { 1712 panic("brelse: page missing\n"); 1713 } 1714 bp->b_pages[j] = mtmp; 1715 } 1716 } 1717 VM_OBJECT_RUNLOCK(obj); 1718 1719 if ((bp->b_flags & (B_INVAL | B_UNMAPPED)) == 0) { 1720 BUF_CHECK_MAPPED(bp); 1721 pmap_qenter( 1722 trunc_page((vm_offset_t)bp->b_data), 1723 bp->b_pages, bp->b_npages); 1724 } 1725 m = bp->b_pages[i]; 1726 } 1727 if ((bp->b_flags & B_NOCACHE) || 1728 (bp->b_ioflags & BIO_ERROR && 1729 bp->b_iocmd == BIO_READ)) { 1730 int poffset = foff & PAGE_MASK; 1731 int presid = resid > (PAGE_SIZE - poffset) ? 1732 (PAGE_SIZE - poffset) : resid; 1733 1734 KASSERT(presid >= 0, ("brelse: extra page")); 1735 VM_OBJECT_WLOCK(obj); 1736 while (vm_page_xbusied(m)) { 1737 vm_page_lock(m); 1738 VM_OBJECT_WUNLOCK(obj); 1739 vm_page_busy_sleep(m, "mbncsh"); 1740 VM_OBJECT_WLOCK(obj); 1741 } 1742 if (pmap_page_wired_mappings(m) == 0) 1743 vm_page_set_invalid(m, poffset, presid); 1744 VM_OBJECT_WUNLOCK(obj); 1745 if (had_bogus) 1746 printf("avoided corruption bug in bogus_page/brelse code\n"); 1747 } 1748 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1749 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1750 } 1751 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1752 vfs_vmio_release(bp); 1753 1754 } else if (bp->b_flags & B_VMIO) { 1755 1756 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1757 vfs_vmio_release(bp); 1758 } 1759 1760 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) { 1761 if (bp->b_bufsize != 0) 1762 allocbuf(bp, 0); 1763 if (bp->b_vp != NULL) 1764 brelvp(bp); 1765 } 1766 1767 /* 1768 * If the buffer has junk contents signal it and eventually 1769 * clean up B_DELWRI and diassociate the vnode so that gbincore() 1770 * doesn't find it. 1771 */ 1772 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 1773 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 1774 bp->b_flags |= B_INVAL; 1775 if (bp->b_flags & B_INVAL) { 1776 if (bp->b_flags & B_DELWRI) 1777 bundirty(bp); 1778 if (bp->b_vp) 1779 brelvp(bp); 1780 } 1781 1782 /* buffers with no memory */ 1783 if (bp->b_bufsize == 0) { 1784 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1785 if (bp->b_vflags & BV_BKGRDINPROG) 1786 panic("losing buffer 1"); 1787 if (bp->b_kvasize) 1788 qindex = QUEUE_EMPTYKVA; 1789 else 1790 qindex = QUEUE_EMPTY; 1791 bp->b_flags |= B_AGE; 1792 /* buffers with junk contents */ 1793 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 1794 (bp->b_ioflags & BIO_ERROR)) { 1795 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1796 if (bp->b_vflags & BV_BKGRDINPROG) 1797 panic("losing buffer 2"); 1798 qindex = QUEUE_CLEAN; 1799 bp->b_flags |= B_AGE; 1800 /* remaining buffers */ 1801 } else if (bp->b_flags & B_DELWRI) 1802 qindex = QUEUE_DIRTY; 1803 else 1804 qindex = QUEUE_CLEAN; 1805 1806 binsfree(bp, qindex); 1807 1808 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 1809 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1810 panic("brelse: not dirty"); 1811 /* unlock */ 1812 BUF_UNLOCK(bp); 1813 } 1814 1815 /* 1816 * Release a buffer back to the appropriate queue but do not try to free 1817 * it. The buffer is expected to be used again soon. 1818 * 1819 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1820 * biodone() to requeue an async I/O on completion. It is also used when 1821 * known good buffers need to be requeued but we think we may need the data 1822 * again soon. 1823 * 1824 * XXX we should be able to leave the B_RELBUF hint set on completion. 1825 */ 1826 void 1827 bqrelse(struct buf *bp) 1828 { 1829 int qindex; 1830 1831 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1832 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1833 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1834 1835 if (BUF_LOCKRECURSED(bp)) { 1836 /* do not release to free list */ 1837 BUF_UNLOCK(bp); 1838 return; 1839 } 1840 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1841 1842 if (bp->b_flags & B_MANAGED) { 1843 if (bp->b_flags & B_REMFREE) 1844 bremfreef(bp); 1845 goto out; 1846 } 1847 1848 /* buffers with stale but valid contents */ 1849 if (bp->b_flags & B_DELWRI) { 1850 qindex = QUEUE_DIRTY; 1851 } else { 1852 if ((bp->b_flags & B_DELWRI) == 0 && 1853 (bp->b_xflags & BX_VNDIRTY)) 1854 panic("bqrelse: not dirty"); 1855 /* 1856 * BKGRDINPROG can only be set with the buf and bufobj 1857 * locks both held. We tolerate a race to clear it here. 1858 */ 1859 if (buf_vm_page_count_severe() && 1860 (bp->b_vflags & BV_BKGRDINPROG) == 0) { 1861 /* 1862 * We are too low on memory, we have to try to free 1863 * the buffer (most importantly: the wired pages 1864 * making up its backing store) *now*. 1865 */ 1866 brelse(bp); 1867 return; 1868 } 1869 qindex = QUEUE_CLEAN; 1870 } 1871 binsfree(bp, qindex); 1872 1873 out: 1874 /* unlock */ 1875 BUF_UNLOCK(bp); 1876 } 1877 1878 /* Give pages used by the bp back to the VM system (where possible) */ 1879 static void 1880 vfs_vmio_release(struct buf *bp) 1881 { 1882 int i; 1883 vm_page_t m; 1884 1885 if ((bp->b_flags & B_UNMAPPED) == 0) { 1886 BUF_CHECK_MAPPED(bp); 1887 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages); 1888 } else 1889 BUF_CHECK_UNMAPPED(bp); 1890 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 1891 for (i = 0; i < bp->b_npages; i++) { 1892 m = bp->b_pages[i]; 1893 bp->b_pages[i] = NULL; 1894 /* 1895 * In order to keep page LRU ordering consistent, put 1896 * everything on the inactive queue. 1897 */ 1898 vm_page_lock(m); 1899 vm_page_unwire(m, PQ_INACTIVE); 1900 1901 /* 1902 * Might as well free the page if we can and it has 1903 * no valid data. We also free the page if the 1904 * buffer was used for direct I/O 1905 */ 1906 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid) { 1907 if (m->wire_count == 0 && !vm_page_busied(m)) 1908 vm_page_free(m); 1909 } else if (bp->b_flags & B_DIRECT) 1910 vm_page_try_to_free(m); 1911 else if (buf_vm_page_count_severe()) 1912 vm_page_try_to_cache(m); 1913 vm_page_unlock(m); 1914 } 1915 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 1916 1917 if (bp->b_bufsize) { 1918 bufspacewakeup(); 1919 bp->b_bufsize = 0; 1920 } 1921 bp->b_npages = 0; 1922 bp->b_flags &= ~B_VMIO; 1923 if (bp->b_vp) 1924 brelvp(bp); 1925 } 1926 1927 /* 1928 * Check to see if a block at a particular lbn is available for a clustered 1929 * write. 1930 */ 1931 static int 1932 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 1933 { 1934 struct buf *bpa; 1935 int match; 1936 1937 match = 0; 1938 1939 /* If the buf isn't in core skip it */ 1940 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 1941 return (0); 1942 1943 /* If the buf is busy we don't want to wait for it */ 1944 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1945 return (0); 1946 1947 /* Only cluster with valid clusterable delayed write buffers */ 1948 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 1949 (B_DELWRI | B_CLUSTEROK)) 1950 goto done; 1951 1952 if (bpa->b_bufsize != size) 1953 goto done; 1954 1955 /* 1956 * Check to see if it is in the expected place on disk and that the 1957 * block has been mapped. 1958 */ 1959 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 1960 match = 1; 1961 done: 1962 BUF_UNLOCK(bpa); 1963 return (match); 1964 } 1965 1966 /* 1967 * vfs_bio_awrite: 1968 * 1969 * Implement clustered async writes for clearing out B_DELWRI buffers. 1970 * This is much better then the old way of writing only one buffer at 1971 * a time. Note that we may not be presented with the buffers in the 1972 * correct order, so we search for the cluster in both directions. 1973 */ 1974 int 1975 vfs_bio_awrite(struct buf *bp) 1976 { 1977 struct bufobj *bo; 1978 int i; 1979 int j; 1980 daddr_t lblkno = bp->b_lblkno; 1981 struct vnode *vp = bp->b_vp; 1982 int ncl; 1983 int nwritten; 1984 int size; 1985 int maxcl; 1986 int gbflags; 1987 1988 bo = &vp->v_bufobj; 1989 gbflags = (bp->b_flags & B_UNMAPPED) != 0 ? GB_UNMAPPED : 0; 1990 /* 1991 * right now we support clustered writing only to regular files. If 1992 * we find a clusterable block we could be in the middle of a cluster 1993 * rather then at the beginning. 1994 */ 1995 if ((vp->v_type == VREG) && 1996 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1997 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1998 1999 size = vp->v_mount->mnt_stat.f_iosize; 2000 maxcl = MAXPHYS / size; 2001 2002 BO_RLOCK(bo); 2003 for (i = 1; i < maxcl; i++) 2004 if (vfs_bio_clcheck(vp, size, lblkno + i, 2005 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 2006 break; 2007 2008 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 2009 if (vfs_bio_clcheck(vp, size, lblkno - j, 2010 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 2011 break; 2012 BO_RUNLOCK(bo); 2013 --j; 2014 ncl = i + j; 2015 /* 2016 * this is a possible cluster write 2017 */ 2018 if (ncl != 1) { 2019 BUF_UNLOCK(bp); 2020 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl, 2021 gbflags); 2022 return (nwritten); 2023 } 2024 } 2025 bremfree(bp); 2026 bp->b_flags |= B_ASYNC; 2027 /* 2028 * default (old) behavior, writing out only one block 2029 * 2030 * XXX returns b_bufsize instead of b_bcount for nwritten? 2031 */ 2032 nwritten = bp->b_bufsize; 2033 (void) bwrite(bp); 2034 2035 return (nwritten); 2036 } 2037 2038 static void 2039 setbufkva(struct buf *bp, vm_offset_t addr, int maxsize, int gbflags) 2040 { 2041 2042 KASSERT((bp->b_flags & (B_UNMAPPED | B_KVAALLOC)) == 0 && 2043 bp->b_kvasize == 0, ("call bfreekva(%p)", bp)); 2044 if ((gbflags & GB_UNMAPPED) == 0) { 2045 bp->b_kvabase = (caddr_t)addr; 2046 } else if ((gbflags & GB_KVAALLOC) != 0) { 2047 KASSERT((gbflags & GB_UNMAPPED) != 0, 2048 ("GB_KVAALLOC without GB_UNMAPPED")); 2049 bp->b_kvaalloc = (caddr_t)addr; 2050 bp->b_flags |= B_UNMAPPED | B_KVAALLOC; 2051 atomic_add_long(&unmapped_bufspace, bp->b_kvasize); 2052 } 2053 bp->b_kvasize = maxsize; 2054 } 2055 2056 /* 2057 * Allocate the buffer KVA and set b_kvasize. Also set b_kvabase if 2058 * needed. 2059 */ 2060 static int 2061 allocbufkva(struct buf *bp, int maxsize, int gbflags) 2062 { 2063 vm_offset_t addr; 2064 2065 bfreekva(bp); 2066 addr = 0; 2067 2068 if (vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr)) { 2069 /* 2070 * Buffer map is too fragmented. Request the caller 2071 * to defragment the map. 2072 */ 2073 atomic_add_int(&bufdefragcnt, 1); 2074 return (1); 2075 } 2076 setbufkva(bp, addr, maxsize, gbflags); 2077 atomic_add_long(&bufspace, bp->b_kvasize); 2078 return (0); 2079 } 2080 2081 /* 2082 * Ask the bufdaemon for help, or act as bufdaemon itself, when a 2083 * locked vnode is supplied. 2084 */ 2085 static void 2086 getnewbuf_bufd_help(struct vnode *vp, int gbflags, int slpflag, int slptimeo, 2087 int defrag) 2088 { 2089 struct thread *td; 2090 char *waitmsg; 2091 int cnt, error, flags, norunbuf, wait; 2092 2093 mtx_assert(&bqclean, MA_OWNED); 2094 2095 if (defrag) { 2096 flags = VFS_BIO_NEED_BUFSPACE; 2097 waitmsg = "nbufkv"; 2098 } else if (bufspace >= hibufspace) { 2099 waitmsg = "nbufbs"; 2100 flags = VFS_BIO_NEED_BUFSPACE; 2101 } else { 2102 waitmsg = "newbuf"; 2103 flags = VFS_BIO_NEED_ANY; 2104 } 2105 atomic_set_int(&needsbuffer, flags); 2106 mtx_unlock(&bqclean); 2107 2108 bd_speedup(); /* heeeelp */ 2109 if ((gbflags & GB_NOWAIT_BD) != 0) 2110 return; 2111 2112 td = curthread; 2113 cnt = 0; 2114 wait = MNT_NOWAIT; 2115 rw_wlock(&nblock); 2116 while ((needsbuffer & flags) != 0) { 2117 if (vp != NULL && vp->v_type != VCHR && 2118 (td->td_pflags & TDP_BUFNEED) == 0) { 2119 rw_wunlock(&nblock); 2120 /* 2121 * getblk() is called with a vnode locked, and 2122 * some majority of the dirty buffers may as 2123 * well belong to the vnode. Flushing the 2124 * buffers there would make a progress that 2125 * cannot be achieved by the buf_daemon, that 2126 * cannot lock the vnode. 2127 */ 2128 if (cnt++ > 2) 2129 wait = MNT_WAIT; 2130 ASSERT_VOP_LOCKED(vp, "bufd_helper"); 2131 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 : 2132 vn_lock(vp, LK_TRYUPGRADE); 2133 if (error == 0) { 2134 /* play bufdaemon */ 2135 norunbuf = curthread_pflags_set(TDP_BUFNEED | 2136 TDP_NORUNNINGBUF); 2137 VOP_FSYNC(vp, wait, td); 2138 atomic_add_long(¬bufdflushes, 1); 2139 curthread_pflags_restore(norunbuf); 2140 } 2141 rw_wlock(&nblock); 2142 if ((needsbuffer & flags) == 0) 2143 break; 2144 } 2145 error = rw_sleep(__DEVOLATILE(void *, &needsbuffer), &nblock, 2146 (PRIBIO + 4) | slpflag, waitmsg, slptimeo); 2147 if (error != 0) 2148 break; 2149 } 2150 rw_wunlock(&nblock); 2151 } 2152 2153 static void 2154 getnewbuf_reuse_bp(struct buf *bp, int qindex) 2155 { 2156 2157 CTR6(KTR_BUF, "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d " 2158 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags, 2159 bp->b_kvasize, bp->b_bufsize, qindex); 2160 mtx_assert(&bqclean, MA_NOTOWNED); 2161 2162 /* 2163 * Note: we no longer distinguish between VMIO and non-VMIO 2164 * buffers. 2165 */ 2166 KASSERT((bp->b_flags & B_DELWRI) == 0, 2167 ("delwri buffer %p found in queue %d", bp, qindex)); 2168 2169 if (qindex == QUEUE_CLEAN) { 2170 if (bp->b_flags & B_VMIO) { 2171 bp->b_flags &= ~B_ASYNC; 2172 vfs_vmio_release(bp); 2173 } 2174 if (bp->b_vp != NULL) 2175 brelvp(bp); 2176 } 2177 2178 /* 2179 * Get the rest of the buffer freed up. b_kva* is still valid 2180 * after this operation. 2181 */ 2182 2183 if (bp->b_rcred != NOCRED) { 2184 crfree(bp->b_rcred); 2185 bp->b_rcred = NOCRED; 2186 } 2187 if (bp->b_wcred != NOCRED) { 2188 crfree(bp->b_wcred); 2189 bp->b_wcred = NOCRED; 2190 } 2191 if (!LIST_EMPTY(&bp->b_dep)) 2192 buf_deallocate(bp); 2193 if (bp->b_vflags & BV_BKGRDINPROG) 2194 panic("losing buffer 3"); 2195 KASSERT(bp->b_vp == NULL, ("bp: %p still has vnode %p. qindex: %d", 2196 bp, bp->b_vp, qindex)); 2197 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 2198 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags)); 2199 2200 if (bp->b_bufsize) 2201 allocbuf(bp, 0); 2202 2203 bp->b_flags &= B_UNMAPPED | B_KVAALLOC; 2204 bp->b_ioflags = 0; 2205 bp->b_xflags = 0; 2206 KASSERT((bp->b_flags & B_INFREECNT) == 0, 2207 ("buf %p still counted as free?", bp)); 2208 bp->b_vflags = 0; 2209 bp->b_vp = NULL; 2210 bp->b_blkno = bp->b_lblkno = 0; 2211 bp->b_offset = NOOFFSET; 2212 bp->b_iodone = 0; 2213 bp->b_error = 0; 2214 bp->b_resid = 0; 2215 bp->b_bcount = 0; 2216 bp->b_npages = 0; 2217 bp->b_dirtyoff = bp->b_dirtyend = 0; 2218 bp->b_bufobj = NULL; 2219 bp->b_pin_count = 0; 2220 bp->b_fsprivate1 = NULL; 2221 bp->b_fsprivate2 = NULL; 2222 bp->b_fsprivate3 = NULL; 2223 2224 LIST_INIT(&bp->b_dep); 2225 } 2226 2227 static int flushingbufs; 2228 2229 static struct buf * 2230 getnewbuf_scan(int maxsize, int defrag, int unmapped, int metadata) 2231 { 2232 struct buf *bp, *nbp; 2233 int nqindex, qindex, pass; 2234 2235 KASSERT(!unmapped || !defrag, ("both unmapped and defrag")); 2236 2237 pass = 1; 2238 restart: 2239 atomic_add_int(&getnewbufrestarts, 1); 2240 2241 /* 2242 * Setup for scan. If we do not have enough free buffers, 2243 * we setup a degenerate case that immediately fails. Note 2244 * that if we are specially marked process, we are allowed to 2245 * dip into our reserves. 2246 * 2247 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 2248 * for the allocation of the mapped buffer. For unmapped, the 2249 * easiest is to start with EMPTY outright. 2250 * 2251 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 2252 * However, there are a number of cases (defragging, reusing, ...) 2253 * where we cannot backup. 2254 */ 2255 nbp = NULL; 2256 mtx_lock(&bqclean); 2257 if (!defrag && unmapped) { 2258 nqindex = QUEUE_EMPTY; 2259 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 2260 } 2261 if (nbp == NULL) { 2262 nqindex = QUEUE_EMPTYKVA; 2263 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 2264 } 2265 2266 /* 2267 * If no EMPTYKVA buffers and we are either defragging or 2268 * reusing, locate a CLEAN buffer to free or reuse. If 2269 * bufspace useage is low skip this step so we can allocate a 2270 * new buffer. 2271 */ 2272 if (nbp == NULL && (defrag || bufspace >= lobufspace)) { 2273 nqindex = QUEUE_CLEAN; 2274 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2275 } 2276 2277 /* 2278 * If we could not find or were not allowed to reuse a CLEAN 2279 * buffer, check to see if it is ok to use an EMPTY buffer. 2280 * We can only use an EMPTY buffer if allocating its KVA would 2281 * not otherwise run us out of buffer space. No KVA is needed 2282 * for the unmapped allocation. 2283 */ 2284 if (nbp == NULL && defrag == 0 && (bufspace + maxsize < hibufspace || 2285 metadata)) { 2286 nqindex = QUEUE_EMPTY; 2287 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 2288 } 2289 2290 /* 2291 * All available buffers might be clean, retry ignoring the 2292 * lobufspace as the last resort. 2293 */ 2294 if (nbp == NULL && !TAILQ_EMPTY(&bufqueues[QUEUE_CLEAN])) { 2295 nqindex = QUEUE_CLEAN; 2296 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2297 } 2298 2299 /* 2300 * Run scan, possibly freeing data and/or kva mappings on the fly 2301 * depending. 2302 */ 2303 while ((bp = nbp) != NULL) { 2304 qindex = nqindex; 2305 2306 /* 2307 * Calculate next bp (we can only use it if we do not 2308 * block or do other fancy things). 2309 */ 2310 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 2311 switch (qindex) { 2312 case QUEUE_EMPTY: 2313 nqindex = QUEUE_EMPTYKVA; 2314 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 2315 if (nbp != NULL) 2316 break; 2317 /* FALLTHROUGH */ 2318 case QUEUE_EMPTYKVA: 2319 nqindex = QUEUE_CLEAN; 2320 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2321 if (nbp != NULL) 2322 break; 2323 /* FALLTHROUGH */ 2324 case QUEUE_CLEAN: 2325 if (metadata && pass == 1) { 2326 pass = 2; 2327 nqindex = QUEUE_EMPTY; 2328 nbp = TAILQ_FIRST( 2329 &bufqueues[QUEUE_EMPTY]); 2330 } 2331 /* 2332 * nbp is NULL. 2333 */ 2334 break; 2335 } 2336 } 2337 /* 2338 * If we are defragging then we need a buffer with 2339 * b_kvasize != 0. XXX this situation should no longer 2340 * occur, if defrag is non-zero the buffer's b_kvasize 2341 * should also be non-zero at this point. XXX 2342 */ 2343 if (defrag && bp->b_kvasize == 0) { 2344 printf("Warning: defrag empty buffer %p\n", bp); 2345 continue; 2346 } 2347 2348 /* 2349 * Start freeing the bp. This is somewhat involved. nbp 2350 * remains valid only for QUEUE_EMPTY[KVA] bp's. 2351 */ 2352 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2353 continue; 2354 /* 2355 * BKGRDINPROG can only be set with the buf and bufobj 2356 * locks both held. We tolerate a race to clear it here. 2357 */ 2358 if (bp->b_vflags & BV_BKGRDINPROG) { 2359 BUF_UNLOCK(bp); 2360 continue; 2361 } 2362 2363 KASSERT(bp->b_qindex == qindex, 2364 ("getnewbuf: inconsistent queue %d bp %p", qindex, bp)); 2365 2366 bremfreel(bp); 2367 mtx_unlock(&bqclean); 2368 /* 2369 * NOTE: nbp is now entirely invalid. We can only restart 2370 * the scan from this point on. 2371 */ 2372 2373 getnewbuf_reuse_bp(bp, qindex); 2374 mtx_assert(&bqclean, MA_NOTOWNED); 2375 2376 /* 2377 * If we are defragging then free the buffer. 2378 */ 2379 if (defrag) { 2380 bp->b_flags |= B_INVAL; 2381 bfreekva(bp); 2382 brelse(bp); 2383 defrag = 0; 2384 goto restart; 2385 } 2386 2387 /* 2388 * Notify any waiters for the buffer lock about 2389 * identity change by freeing the buffer. 2390 */ 2391 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp)) { 2392 bp->b_flags |= B_INVAL; 2393 bfreekva(bp); 2394 brelse(bp); 2395 goto restart; 2396 } 2397 2398 if (metadata) 2399 break; 2400 2401 /* 2402 * If we are overcomitted then recover the buffer and its 2403 * KVM space. This occurs in rare situations when multiple 2404 * processes are blocked in getnewbuf() or allocbuf(). 2405 */ 2406 if (bufspace >= hibufspace) 2407 flushingbufs = 1; 2408 if (flushingbufs && bp->b_kvasize != 0) { 2409 bp->b_flags |= B_INVAL; 2410 bfreekva(bp); 2411 brelse(bp); 2412 goto restart; 2413 } 2414 if (bufspace < lobufspace) 2415 flushingbufs = 0; 2416 break; 2417 } 2418 return (bp); 2419 } 2420 2421 /* 2422 * getnewbuf: 2423 * 2424 * Find and initialize a new buffer header, freeing up existing buffers 2425 * in the bufqueues as necessary. The new buffer is returned locked. 2426 * 2427 * Important: B_INVAL is not set. If the caller wishes to throw the 2428 * buffer away, the caller must set B_INVAL prior to calling brelse(). 2429 * 2430 * We block if: 2431 * We have insufficient buffer headers 2432 * We have insufficient buffer space 2433 * buffer_arena is too fragmented ( space reservation fails ) 2434 * If we have to flush dirty buffers ( but we try to avoid this ) 2435 */ 2436 static struct buf * 2437 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int size, int maxsize, 2438 int gbflags) 2439 { 2440 struct buf *bp; 2441 int defrag, metadata; 2442 2443 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 2444 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 2445 if (!unmapped_buf_allowed) 2446 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC); 2447 2448 defrag = 0; 2449 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 || 2450 vp->v_type == VCHR) 2451 metadata = 1; 2452 else 2453 metadata = 0; 2454 /* 2455 * We can't afford to block since we might be holding a vnode lock, 2456 * which may prevent system daemons from running. We deal with 2457 * low-memory situations by proactively returning memory and running 2458 * async I/O rather then sync I/O. 2459 */ 2460 atomic_add_int(&getnewbufcalls, 1); 2461 atomic_subtract_int(&getnewbufrestarts, 1); 2462 restart: 2463 bp = getnewbuf_scan(maxsize, defrag, (gbflags & (GB_UNMAPPED | 2464 GB_KVAALLOC)) == GB_UNMAPPED, metadata); 2465 if (bp != NULL) 2466 defrag = 0; 2467 2468 /* 2469 * If we exhausted our list, sleep as appropriate. We may have to 2470 * wakeup various daemons and write out some dirty buffers. 2471 * 2472 * Generally we are sleeping due to insufficient buffer space. 2473 */ 2474 if (bp == NULL) { 2475 mtx_assert(&bqclean, MA_OWNED); 2476 getnewbuf_bufd_help(vp, gbflags, slpflag, slptimeo, defrag); 2477 mtx_assert(&bqclean, MA_NOTOWNED); 2478 } else if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == GB_UNMAPPED) { 2479 mtx_assert(&bqclean, MA_NOTOWNED); 2480 2481 bfreekva(bp); 2482 bp->b_flags |= B_UNMAPPED; 2483 bp->b_kvabase = bp->b_data = unmapped_buf; 2484 bp->b_kvasize = maxsize; 2485 atomic_add_long(&bufspace, bp->b_kvasize); 2486 atomic_add_long(&unmapped_bufspace, bp->b_kvasize); 2487 atomic_add_int(&bufreusecnt, 1); 2488 } else { 2489 mtx_assert(&bqclean, MA_NOTOWNED); 2490 2491 /* 2492 * We finally have a valid bp. We aren't quite out of the 2493 * woods, we still have to reserve kva space. In order 2494 * to keep fragmentation sane we only allocate kva in 2495 * BKVASIZE chunks. 2496 */ 2497 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2498 2499 if (maxsize != bp->b_kvasize || (bp->b_flags & (B_UNMAPPED | 2500 B_KVAALLOC)) == B_UNMAPPED) { 2501 if (allocbufkva(bp, maxsize, gbflags)) { 2502 defrag = 1; 2503 bp->b_flags |= B_INVAL; 2504 brelse(bp); 2505 goto restart; 2506 } 2507 atomic_add_int(&bufreusecnt, 1); 2508 } else if ((bp->b_flags & B_KVAALLOC) != 0 && 2509 (gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == 0) { 2510 /* 2511 * If the reused buffer has KVA allocated, 2512 * reassign b_kvaalloc to b_kvabase. 2513 */ 2514 bp->b_kvabase = bp->b_kvaalloc; 2515 bp->b_flags &= ~B_KVAALLOC; 2516 atomic_subtract_long(&unmapped_bufspace, 2517 bp->b_kvasize); 2518 atomic_add_int(&bufreusecnt, 1); 2519 } else if ((bp->b_flags & (B_UNMAPPED | B_KVAALLOC)) == 0 && 2520 (gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == (GB_UNMAPPED | 2521 GB_KVAALLOC)) { 2522 /* 2523 * The case of reused buffer already have KVA 2524 * mapped, but the request is for unmapped 2525 * buffer with KVA allocated. 2526 */ 2527 bp->b_kvaalloc = bp->b_kvabase; 2528 bp->b_data = bp->b_kvabase = unmapped_buf; 2529 bp->b_flags |= B_UNMAPPED | B_KVAALLOC; 2530 atomic_add_long(&unmapped_bufspace, 2531 bp->b_kvasize); 2532 atomic_add_int(&bufreusecnt, 1); 2533 } 2534 if ((gbflags & GB_UNMAPPED) == 0) { 2535 bp->b_saveaddr = bp->b_kvabase; 2536 bp->b_data = bp->b_saveaddr; 2537 bp->b_flags &= ~B_UNMAPPED; 2538 BUF_CHECK_MAPPED(bp); 2539 } 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(int target) 2561 { 2562 int flushed; 2563 2564 flushed = flushbufqueues(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 flushed = flushbufqueues(target, 1); 2572 } 2573 return (flushed); 2574 } 2575 2576 static void 2577 buf_daemon() 2578 { 2579 int lodirty; 2580 2581 /* 2582 * This process needs to be suspended prior to shutdown sync. 2583 */ 2584 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2585 SHUTDOWN_PRI_LAST); 2586 2587 /* 2588 * This process is allowed to take the buffer cache to the limit 2589 */ 2590 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 2591 mtx_lock(&bdlock); 2592 for (;;) { 2593 bd_request = 0; 2594 mtx_unlock(&bdlock); 2595 2596 kproc_suspend_check(bufdaemonproc); 2597 lodirty = lodirtybuffers; 2598 if (bd_speedupreq) { 2599 lodirty = numdirtybuffers / 2; 2600 bd_speedupreq = 0; 2601 } 2602 /* 2603 * Do the flush. Limit the amount of in-transit I/O we 2604 * allow to build up, otherwise we would completely saturate 2605 * the I/O system. 2606 */ 2607 while (numdirtybuffers > lodirty) { 2608 if (buf_flush(numdirtybuffers - lodirty) == 0) 2609 break; 2610 kern_yield(PRI_USER); 2611 } 2612 2613 /* 2614 * Only clear bd_request if we have reached our low water 2615 * mark. The buf_daemon normally waits 1 second and 2616 * then incrementally flushes any dirty buffers that have 2617 * built up, within reason. 2618 * 2619 * If we were unable to hit our low water mark and couldn't 2620 * find any flushable buffers, we sleep for a short period 2621 * to avoid endless loops on unlockable buffers. 2622 */ 2623 mtx_lock(&bdlock); 2624 if (numdirtybuffers <= lodirtybuffers) { 2625 /* 2626 * We reached our low water mark, reset the 2627 * request and sleep until we are needed again. 2628 * The sleep is just so the suspend code works. 2629 */ 2630 bd_request = 0; 2631 /* 2632 * Do an extra wakeup in case dirty threshold 2633 * changed via sysctl and the explicit transition 2634 * out of shortfall was missed. 2635 */ 2636 bdirtywakeup(); 2637 if (runningbufspace <= lorunningspace) 2638 runningwakeup(); 2639 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 2640 } else { 2641 /* 2642 * We couldn't find any flushable dirty buffers but 2643 * still have too many dirty buffers, we 2644 * have to sleep and try again. (rare) 2645 */ 2646 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 2647 } 2648 } 2649 } 2650 2651 /* 2652 * flushbufqueues: 2653 * 2654 * Try to flush a buffer in the dirty queue. We must be careful to 2655 * free up B_INVAL buffers instead of write them, which NFS is 2656 * particularly sensitive to. 2657 */ 2658 static int flushwithdeps = 0; 2659 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 2660 0, "Number of buffers flushed with dependecies that require rollbacks"); 2661 2662 static int 2663 flushbufqueues(int target, int flushdeps) 2664 { 2665 struct buf *sentinel; 2666 struct vnode *vp; 2667 struct mount *mp; 2668 struct buf *bp; 2669 int hasdeps; 2670 int flushed; 2671 int queue; 2672 int error; 2673 2674 flushed = 0; 2675 queue = QUEUE_DIRTY; 2676 bp = NULL; 2677 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 2678 sentinel->b_qindex = QUEUE_SENTINEL; 2679 mtx_lock(&bqdirty); 2680 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist); 2681 mtx_unlock(&bqdirty); 2682 while (flushed != target) { 2683 maybe_yield(); 2684 mtx_lock(&bqdirty); 2685 bp = TAILQ_NEXT(sentinel, b_freelist); 2686 if (bp != NULL) { 2687 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2688 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel, 2689 b_freelist); 2690 } else { 2691 mtx_unlock(&bqdirty); 2692 break; 2693 } 2694 KASSERT(bp->b_qindex != QUEUE_SENTINEL, 2695 ("parallel calls to flushbufqueues() bp %p", bp)); 2696 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL); 2697 mtx_unlock(&bqdirty); 2698 if (error != 0) 2699 continue; 2700 if (bp->b_pin_count > 0) { 2701 BUF_UNLOCK(bp); 2702 continue; 2703 } 2704 /* 2705 * BKGRDINPROG can only be set with the buf and bufobj 2706 * locks both held. We tolerate a race to clear it here. 2707 */ 2708 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 2709 (bp->b_flags & B_DELWRI) == 0) { 2710 BUF_UNLOCK(bp); 2711 continue; 2712 } 2713 if (bp->b_flags & B_INVAL) { 2714 bremfreef(bp); 2715 brelse(bp); 2716 flushed++; 2717 continue; 2718 } 2719 2720 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 2721 if (flushdeps == 0) { 2722 BUF_UNLOCK(bp); 2723 continue; 2724 } 2725 hasdeps = 1; 2726 } else 2727 hasdeps = 0; 2728 /* 2729 * We must hold the lock on a vnode before writing 2730 * one of its buffers. Otherwise we may confuse, or 2731 * in the case of a snapshot vnode, deadlock the 2732 * system. 2733 * 2734 * The lock order here is the reverse of the normal 2735 * of vnode followed by buf lock. This is ok because 2736 * the NOWAIT will prevent deadlock. 2737 */ 2738 vp = bp->b_vp; 2739 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 2740 BUF_UNLOCK(bp); 2741 continue; 2742 } 2743 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT); 2744 if (error == 0) { 2745 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 2746 bp, bp->b_vp, bp->b_flags); 2747 vfs_bio_awrite(bp); 2748 vn_finished_write(mp); 2749 VOP_UNLOCK(vp, 0); 2750 flushwithdeps += hasdeps; 2751 flushed++; 2752 if (runningbufspace > hirunningspace) 2753 waitrunningbufspace(); 2754 continue; 2755 } 2756 vn_finished_write(mp); 2757 BUF_UNLOCK(bp); 2758 } 2759 mtx_lock(&bqdirty); 2760 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2761 mtx_unlock(&bqdirty); 2762 free(sentinel, M_TEMP); 2763 return (flushed); 2764 } 2765 2766 /* 2767 * Check to see if a block is currently memory resident. 2768 */ 2769 struct buf * 2770 incore(struct bufobj *bo, daddr_t blkno) 2771 { 2772 struct buf *bp; 2773 2774 BO_RLOCK(bo); 2775 bp = gbincore(bo, blkno); 2776 BO_RUNLOCK(bo); 2777 return (bp); 2778 } 2779 2780 /* 2781 * Returns true if no I/O is needed to access the 2782 * associated VM object. This is like incore except 2783 * it also hunts around in the VM system for the data. 2784 */ 2785 2786 static int 2787 inmem(struct vnode * vp, daddr_t blkno) 2788 { 2789 vm_object_t obj; 2790 vm_offset_t toff, tinc, size; 2791 vm_page_t m; 2792 vm_ooffset_t off; 2793 2794 ASSERT_VOP_LOCKED(vp, "inmem"); 2795 2796 if (incore(&vp->v_bufobj, blkno)) 2797 return 1; 2798 if (vp->v_mount == NULL) 2799 return 0; 2800 obj = vp->v_object; 2801 if (obj == NULL) 2802 return (0); 2803 2804 size = PAGE_SIZE; 2805 if (size > vp->v_mount->mnt_stat.f_iosize) 2806 size = vp->v_mount->mnt_stat.f_iosize; 2807 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2808 2809 VM_OBJECT_RLOCK(obj); 2810 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2811 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2812 if (!m) 2813 goto notinmem; 2814 tinc = size; 2815 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2816 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2817 if (vm_page_is_valid(m, 2818 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2819 goto notinmem; 2820 } 2821 VM_OBJECT_RUNLOCK(obj); 2822 return 1; 2823 2824 notinmem: 2825 VM_OBJECT_RUNLOCK(obj); 2826 return (0); 2827 } 2828 2829 /* 2830 * Set the dirty range for a buffer based on the status of the dirty 2831 * bits in the pages comprising the buffer. The range is limited 2832 * to the size of the buffer. 2833 * 2834 * Tell the VM system that the pages associated with this buffer 2835 * are clean. This is used for delayed writes where the data is 2836 * going to go to disk eventually without additional VM intevention. 2837 * 2838 * Note that while we only really need to clean through to b_bcount, we 2839 * just go ahead and clean through to b_bufsize. 2840 */ 2841 static void 2842 vfs_clean_pages_dirty_buf(struct buf *bp) 2843 { 2844 vm_ooffset_t foff, noff, eoff; 2845 vm_page_t m; 2846 int i; 2847 2848 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 2849 return; 2850 2851 foff = bp->b_offset; 2852 KASSERT(bp->b_offset != NOOFFSET, 2853 ("vfs_clean_pages_dirty_buf: no buffer offset")); 2854 2855 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 2856 vfs_drain_busy_pages(bp); 2857 vfs_setdirty_locked_object(bp); 2858 for (i = 0; i < bp->b_npages; i++) { 2859 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2860 eoff = noff; 2861 if (eoff > bp->b_offset + bp->b_bufsize) 2862 eoff = bp->b_offset + bp->b_bufsize; 2863 m = bp->b_pages[i]; 2864 vfs_page_set_validclean(bp, foff, m); 2865 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 2866 foff = noff; 2867 } 2868 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 2869 } 2870 2871 static void 2872 vfs_setdirty_locked_object(struct buf *bp) 2873 { 2874 vm_object_t object; 2875 int i; 2876 2877 object = bp->b_bufobj->bo_object; 2878 VM_OBJECT_ASSERT_WLOCKED(object); 2879 2880 /* 2881 * We qualify the scan for modified pages on whether the 2882 * object has been flushed yet. 2883 */ 2884 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) { 2885 vm_offset_t boffset; 2886 vm_offset_t eoffset; 2887 2888 /* 2889 * test the pages to see if they have been modified directly 2890 * by users through the VM system. 2891 */ 2892 for (i = 0; i < bp->b_npages; i++) 2893 vm_page_test_dirty(bp->b_pages[i]); 2894 2895 /* 2896 * Calculate the encompassing dirty range, boffset and eoffset, 2897 * (eoffset - boffset) bytes. 2898 */ 2899 2900 for (i = 0; i < bp->b_npages; i++) { 2901 if (bp->b_pages[i]->dirty) 2902 break; 2903 } 2904 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2905 2906 for (i = bp->b_npages - 1; i >= 0; --i) { 2907 if (bp->b_pages[i]->dirty) { 2908 break; 2909 } 2910 } 2911 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2912 2913 /* 2914 * Fit it to the buffer. 2915 */ 2916 2917 if (eoffset > bp->b_bcount) 2918 eoffset = bp->b_bcount; 2919 2920 /* 2921 * If we have a good dirty range, merge with the existing 2922 * dirty range. 2923 */ 2924 2925 if (boffset < eoffset) { 2926 if (bp->b_dirtyoff > boffset) 2927 bp->b_dirtyoff = boffset; 2928 if (bp->b_dirtyend < eoffset) 2929 bp->b_dirtyend = eoffset; 2930 } 2931 } 2932 } 2933 2934 /* 2935 * Allocate the KVA mapping for an existing buffer. It handles the 2936 * cases of both B_UNMAPPED buffer, and buffer with the preallocated 2937 * KVA which is not mapped (B_KVAALLOC). 2938 */ 2939 static void 2940 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags) 2941 { 2942 struct buf *scratch_bp; 2943 int bsize, maxsize, need_mapping, need_kva; 2944 off_t offset; 2945 2946 need_mapping = (bp->b_flags & B_UNMAPPED) != 0 && 2947 (gbflags & GB_UNMAPPED) == 0; 2948 need_kva = (bp->b_flags & (B_KVAALLOC | B_UNMAPPED)) == B_UNMAPPED && 2949 (gbflags & GB_KVAALLOC) != 0; 2950 if (!need_mapping && !need_kva) 2951 return; 2952 2953 BUF_CHECK_UNMAPPED(bp); 2954 2955 if (need_mapping && (bp->b_flags & B_KVAALLOC) != 0) { 2956 /* 2957 * Buffer is not mapped, but the KVA was already 2958 * reserved at the time of the instantiation. Use the 2959 * allocated space. 2960 */ 2961 bp->b_flags &= ~B_KVAALLOC; 2962 KASSERT(bp->b_kvaalloc != 0, ("kvaalloc == 0")); 2963 bp->b_kvabase = bp->b_kvaalloc; 2964 atomic_subtract_long(&unmapped_bufspace, bp->b_kvasize); 2965 goto has_addr; 2966 } 2967 2968 /* 2969 * Calculate the amount of the address space we would reserve 2970 * if the buffer was mapped. 2971 */ 2972 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize; 2973 offset = blkno * bsize; 2974 maxsize = size + (offset & PAGE_MASK); 2975 maxsize = imax(maxsize, bsize); 2976 2977 mapping_loop: 2978 if (allocbufkva(bp, maxsize, gbflags)) { 2979 /* 2980 * Request defragmentation. getnewbuf() returns us the 2981 * allocated space by the scratch buffer KVA. 2982 */ 2983 scratch_bp = getnewbuf(bp->b_vp, 0, 0, size, maxsize, gbflags | 2984 (GB_UNMAPPED | GB_KVAALLOC)); 2985 if (scratch_bp == NULL) { 2986 if ((gbflags & GB_NOWAIT_BD) != 0) { 2987 /* 2988 * XXXKIB: defragmentation cannot 2989 * succeed, not sure what else to do. 2990 */ 2991 panic("GB_NOWAIT_BD and B_UNMAPPED %p", bp); 2992 } 2993 atomic_add_int(&mappingrestarts, 1); 2994 goto mapping_loop; 2995 } 2996 KASSERT((scratch_bp->b_flags & B_KVAALLOC) != 0, 2997 ("scratch bp !B_KVAALLOC %p", scratch_bp)); 2998 setbufkva(bp, (vm_offset_t)scratch_bp->b_kvaalloc, 2999 scratch_bp->b_kvasize, gbflags); 3000 3001 /* Get rid of the scratch buffer. */ 3002 scratch_bp->b_kvasize = 0; 3003 scratch_bp->b_flags |= B_INVAL; 3004 scratch_bp->b_flags &= ~(B_UNMAPPED | B_KVAALLOC); 3005 brelse(scratch_bp); 3006 } 3007 if (!need_mapping) 3008 return; 3009 3010 has_addr: 3011 bp->b_saveaddr = bp->b_kvabase; 3012 bp->b_data = bp->b_saveaddr; /* b_offset is handled by bpmap_qenter */ 3013 bp->b_flags &= ~B_UNMAPPED; 3014 BUF_CHECK_MAPPED(bp); 3015 bpmap_qenter(bp); 3016 } 3017 3018 /* 3019 * getblk: 3020 * 3021 * Get a block given a specified block and offset into a file/device. 3022 * The buffers B_DONE bit will be cleared on return, making it almost 3023 * ready for an I/O initiation. B_INVAL may or may not be set on 3024 * return. The caller should clear B_INVAL prior to initiating a 3025 * READ. 3026 * 3027 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 3028 * an existing buffer. 3029 * 3030 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 3031 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 3032 * and then cleared based on the backing VM. If the previous buffer is 3033 * non-0-sized but invalid, B_CACHE will be cleared. 3034 * 3035 * If getblk() must create a new buffer, the new buffer is returned with 3036 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 3037 * case it is returned with B_INVAL clear and B_CACHE set based on the 3038 * backing VM. 3039 * 3040 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 3041 * B_CACHE bit is clear. 3042 * 3043 * What this means, basically, is that the caller should use B_CACHE to 3044 * determine whether the buffer is fully valid or not and should clear 3045 * B_INVAL prior to issuing a read. If the caller intends to validate 3046 * the buffer by loading its data area with something, the caller needs 3047 * to clear B_INVAL. If the caller does this without issuing an I/O, 3048 * the caller should set B_CACHE ( as an optimization ), else the caller 3049 * should issue the I/O and biodone() will set B_CACHE if the I/O was 3050 * a write attempt or if it was a successfull read. If the caller 3051 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 3052 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 3053 */ 3054 struct buf * 3055 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3056 int flags) 3057 { 3058 struct buf *bp; 3059 struct bufobj *bo; 3060 int bsize, error, maxsize, vmio; 3061 off_t offset; 3062 3063 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 3064 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3065 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3066 ASSERT_VOP_LOCKED(vp, "getblk"); 3067 if (size > MAXBSIZE) 3068 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 3069 if (!unmapped_buf_allowed) 3070 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3071 3072 bo = &vp->v_bufobj; 3073 loop: 3074 BO_RLOCK(bo); 3075 bp = gbincore(bo, blkno); 3076 if (bp != NULL) { 3077 int lockflags; 3078 /* 3079 * Buffer is in-core. If the buffer is not busy nor managed, 3080 * it must be on a queue. 3081 */ 3082 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 3083 3084 if (flags & GB_LOCK_NOWAIT) 3085 lockflags |= LK_NOWAIT; 3086 3087 error = BUF_TIMELOCK(bp, lockflags, 3088 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo); 3089 3090 /* 3091 * If we slept and got the lock we have to restart in case 3092 * the buffer changed identities. 3093 */ 3094 if (error == ENOLCK) 3095 goto loop; 3096 /* We timed out or were interrupted. */ 3097 else if (error) 3098 return (NULL); 3099 /* If recursed, assume caller knows the rules. */ 3100 else if (BUF_LOCKRECURSED(bp)) 3101 goto end; 3102 3103 /* 3104 * The buffer is locked. B_CACHE is cleared if the buffer is 3105 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 3106 * and for a VMIO buffer B_CACHE is adjusted according to the 3107 * backing VM cache. 3108 */ 3109 if (bp->b_flags & B_INVAL) 3110 bp->b_flags &= ~B_CACHE; 3111 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 3112 bp->b_flags |= B_CACHE; 3113 if (bp->b_flags & B_MANAGED) 3114 MPASS(bp->b_qindex == QUEUE_NONE); 3115 else 3116 bremfree(bp); 3117 3118 /* 3119 * check for size inconsistencies for non-VMIO case. 3120 */ 3121 if (bp->b_bcount != size) { 3122 if ((bp->b_flags & B_VMIO) == 0 || 3123 (size > bp->b_kvasize)) { 3124 if (bp->b_flags & B_DELWRI) { 3125 /* 3126 * If buffer is pinned and caller does 3127 * not want sleep waiting for it to be 3128 * unpinned, bail out 3129 * */ 3130 if (bp->b_pin_count > 0) { 3131 if (flags & GB_LOCK_NOWAIT) { 3132 bqrelse(bp); 3133 return (NULL); 3134 } else { 3135 bunpin_wait(bp); 3136 } 3137 } 3138 bp->b_flags |= B_NOCACHE; 3139 bwrite(bp); 3140 } else { 3141 if (LIST_EMPTY(&bp->b_dep)) { 3142 bp->b_flags |= B_RELBUF; 3143 brelse(bp); 3144 } else { 3145 bp->b_flags |= B_NOCACHE; 3146 bwrite(bp); 3147 } 3148 } 3149 goto loop; 3150 } 3151 } 3152 3153 /* 3154 * Handle the case of unmapped buffer which should 3155 * become mapped, or the buffer for which KVA 3156 * reservation is requested. 3157 */ 3158 bp_unmapped_get_kva(bp, blkno, size, flags); 3159 3160 /* 3161 * If the size is inconsistant in the VMIO case, we can resize 3162 * the buffer. This might lead to B_CACHE getting set or 3163 * cleared. If the size has not changed, B_CACHE remains 3164 * unchanged from its previous state. 3165 */ 3166 if (bp->b_bcount != size) 3167 allocbuf(bp, size); 3168 3169 KASSERT(bp->b_offset != NOOFFSET, 3170 ("getblk: no buffer offset")); 3171 3172 /* 3173 * A buffer with B_DELWRI set and B_CACHE clear must 3174 * be committed before we can return the buffer in 3175 * order to prevent the caller from issuing a read 3176 * ( due to B_CACHE not being set ) and overwriting 3177 * it. 3178 * 3179 * Most callers, including NFS and FFS, need this to 3180 * operate properly either because they assume they 3181 * can issue a read if B_CACHE is not set, or because 3182 * ( for example ) an uncached B_DELWRI might loop due 3183 * to softupdates re-dirtying the buffer. In the latter 3184 * case, B_CACHE is set after the first write completes, 3185 * preventing further loops. 3186 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 3187 * above while extending the buffer, we cannot allow the 3188 * buffer to remain with B_CACHE set after the write 3189 * completes or it will represent a corrupt state. To 3190 * deal with this we set B_NOCACHE to scrap the buffer 3191 * after the write. 3192 * 3193 * We might be able to do something fancy, like setting 3194 * B_CACHE in bwrite() except if B_DELWRI is already set, 3195 * so the below call doesn't set B_CACHE, but that gets real 3196 * confusing. This is much easier. 3197 */ 3198 3199 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 3200 bp->b_flags |= B_NOCACHE; 3201 bwrite(bp); 3202 goto loop; 3203 } 3204 bp->b_flags &= ~B_DONE; 3205 } else { 3206 /* 3207 * Buffer is not in-core, create new buffer. The buffer 3208 * returned by getnewbuf() is locked. Note that the returned 3209 * buffer is also considered valid (not marked B_INVAL). 3210 */ 3211 BO_RUNLOCK(bo); 3212 /* 3213 * If the user does not want us to create the buffer, bail out 3214 * here. 3215 */ 3216 if (flags & GB_NOCREAT) 3217 return NULL; 3218 if (numfreebuffers == 0 && TD_IS_IDLETHREAD(curthread)) 3219 return NULL; 3220 3221 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize; 3222 offset = blkno * bsize; 3223 vmio = vp->v_object != NULL; 3224 if (vmio) { 3225 maxsize = size + (offset & PAGE_MASK); 3226 } else { 3227 maxsize = size; 3228 /* Do not allow non-VMIO notmapped buffers. */ 3229 flags &= ~GB_UNMAPPED; 3230 } 3231 maxsize = imax(maxsize, bsize); 3232 3233 bp = getnewbuf(vp, slpflag, slptimeo, size, maxsize, flags); 3234 if (bp == NULL) { 3235 if (slpflag || slptimeo) 3236 return NULL; 3237 goto loop; 3238 } 3239 3240 /* 3241 * This code is used to make sure that a buffer is not 3242 * created while the getnewbuf routine is blocked. 3243 * This can be a problem whether the vnode is locked or not. 3244 * If the buffer is created out from under us, we have to 3245 * throw away the one we just created. 3246 * 3247 * Note: this must occur before we associate the buffer 3248 * with the vp especially considering limitations in 3249 * the splay tree implementation when dealing with duplicate 3250 * lblkno's. 3251 */ 3252 BO_LOCK(bo); 3253 if (gbincore(bo, blkno)) { 3254 BO_UNLOCK(bo); 3255 bp->b_flags |= B_INVAL; 3256 brelse(bp); 3257 goto loop; 3258 } 3259 3260 /* 3261 * Insert the buffer into the hash, so that it can 3262 * be found by incore. 3263 */ 3264 bp->b_blkno = bp->b_lblkno = blkno; 3265 bp->b_offset = offset; 3266 bgetvp(vp, bp); 3267 BO_UNLOCK(bo); 3268 3269 /* 3270 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 3271 * buffer size starts out as 0, B_CACHE will be set by 3272 * allocbuf() for the VMIO case prior to it testing the 3273 * backing store for validity. 3274 */ 3275 3276 if (vmio) { 3277 bp->b_flags |= B_VMIO; 3278 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 3279 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 3280 bp, vp->v_object, bp->b_bufobj->bo_object)); 3281 } else { 3282 bp->b_flags &= ~B_VMIO; 3283 KASSERT(bp->b_bufobj->bo_object == NULL, 3284 ("ARGH! has b_bufobj->bo_object %p %p\n", 3285 bp, bp->b_bufobj->bo_object)); 3286 BUF_CHECK_MAPPED(bp); 3287 } 3288 3289 allocbuf(bp, size); 3290 bp->b_flags &= ~B_DONE; 3291 } 3292 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 3293 BUF_ASSERT_HELD(bp); 3294 end: 3295 KASSERT(bp->b_bufobj == bo, 3296 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 3297 return (bp); 3298 } 3299 3300 /* 3301 * Get an empty, disassociated buffer of given size. The buffer is initially 3302 * set to B_INVAL. 3303 */ 3304 struct buf * 3305 geteblk(int size, int flags) 3306 { 3307 struct buf *bp; 3308 int maxsize; 3309 3310 maxsize = (size + BKVAMASK) & ~BKVAMASK; 3311 while ((bp = getnewbuf(NULL, 0, 0, size, maxsize, flags)) == NULL) { 3312 if ((flags & GB_NOWAIT_BD) && 3313 (curthread->td_pflags & TDP_BUFNEED) != 0) 3314 return (NULL); 3315 } 3316 allocbuf(bp, size); 3317 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 3318 BUF_ASSERT_HELD(bp); 3319 return (bp); 3320 } 3321 3322 3323 /* 3324 * This code constitutes the buffer memory from either anonymous system 3325 * memory (in the case of non-VMIO operations) or from an associated 3326 * VM object (in the case of VMIO operations). This code is able to 3327 * resize a buffer up or down. 3328 * 3329 * Note that this code is tricky, and has many complications to resolve 3330 * deadlock or inconsistant data situations. Tread lightly!!! 3331 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 3332 * the caller. Calling this code willy nilly can result in the loss of data. 3333 * 3334 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 3335 * B_CACHE for the non-VMIO case. 3336 */ 3337 3338 int 3339 allocbuf(struct buf *bp, int size) 3340 { 3341 int newbsize, mbsize; 3342 int i; 3343 3344 BUF_ASSERT_HELD(bp); 3345 3346 if (bp->b_kvasize < size) 3347 panic("allocbuf: buffer too small"); 3348 3349 if ((bp->b_flags & B_VMIO) == 0) { 3350 caddr_t origbuf; 3351 int origbufsize; 3352 /* 3353 * Just get anonymous memory from the kernel. Don't 3354 * mess with B_CACHE. 3355 */ 3356 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3357 if (bp->b_flags & B_MALLOC) 3358 newbsize = mbsize; 3359 else 3360 newbsize = round_page(size); 3361 3362 if (newbsize < bp->b_bufsize) { 3363 /* 3364 * malloced buffers are not shrunk 3365 */ 3366 if (bp->b_flags & B_MALLOC) { 3367 if (newbsize) { 3368 bp->b_bcount = size; 3369 } else { 3370 free(bp->b_data, M_BIOBUF); 3371 if (bp->b_bufsize) { 3372 atomic_subtract_long( 3373 &bufmallocspace, 3374 bp->b_bufsize); 3375 bufspacewakeup(); 3376 bp->b_bufsize = 0; 3377 } 3378 bp->b_saveaddr = bp->b_kvabase; 3379 bp->b_data = bp->b_saveaddr; 3380 bp->b_bcount = 0; 3381 bp->b_flags &= ~B_MALLOC; 3382 } 3383 return 1; 3384 } 3385 vm_hold_free_pages(bp, newbsize); 3386 } else if (newbsize > bp->b_bufsize) { 3387 /* 3388 * We only use malloced memory on the first allocation. 3389 * and revert to page-allocated memory when the buffer 3390 * grows. 3391 */ 3392 /* 3393 * There is a potential smp race here that could lead 3394 * to bufmallocspace slightly passing the max. It 3395 * is probably extremely rare and not worth worrying 3396 * over. 3397 */ 3398 if ( (bufmallocspace < maxbufmallocspace) && 3399 (bp->b_bufsize == 0) && 3400 (mbsize <= PAGE_SIZE/2)) { 3401 3402 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 3403 bp->b_bufsize = mbsize; 3404 bp->b_bcount = size; 3405 bp->b_flags |= B_MALLOC; 3406 atomic_add_long(&bufmallocspace, mbsize); 3407 return 1; 3408 } 3409 origbuf = NULL; 3410 origbufsize = 0; 3411 /* 3412 * If the buffer is growing on its other-than-first allocation, 3413 * then we revert to the page-allocation scheme. 3414 */ 3415 if (bp->b_flags & B_MALLOC) { 3416 origbuf = bp->b_data; 3417 origbufsize = bp->b_bufsize; 3418 bp->b_data = bp->b_kvabase; 3419 if (bp->b_bufsize) { 3420 atomic_subtract_long(&bufmallocspace, 3421 bp->b_bufsize); 3422 bufspacewakeup(); 3423 bp->b_bufsize = 0; 3424 } 3425 bp->b_flags &= ~B_MALLOC; 3426 newbsize = round_page(newbsize); 3427 } 3428 vm_hold_load_pages( 3429 bp, 3430 (vm_offset_t) bp->b_data + bp->b_bufsize, 3431 (vm_offset_t) bp->b_data + newbsize); 3432 if (origbuf) { 3433 bcopy(origbuf, bp->b_data, origbufsize); 3434 free(origbuf, M_BIOBUF); 3435 } 3436 } 3437 } else { 3438 int desiredpages; 3439 3440 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3441 desiredpages = (size == 0) ? 0 : 3442 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 3443 3444 if (bp->b_flags & B_MALLOC) 3445 panic("allocbuf: VMIO buffer can't be malloced"); 3446 /* 3447 * Set B_CACHE initially if buffer is 0 length or will become 3448 * 0-length. 3449 */ 3450 if (size == 0 || bp->b_bufsize == 0) 3451 bp->b_flags |= B_CACHE; 3452 3453 if (newbsize < bp->b_bufsize) { 3454 /* 3455 * DEV_BSIZE aligned new buffer size is less then the 3456 * DEV_BSIZE aligned existing buffer size. Figure out 3457 * if we have to remove any pages. 3458 */ 3459 if (desiredpages < bp->b_npages) { 3460 vm_page_t m; 3461 3462 if ((bp->b_flags & B_UNMAPPED) == 0) { 3463 BUF_CHECK_MAPPED(bp); 3464 pmap_qremove((vm_offset_t)trunc_page( 3465 (vm_offset_t)bp->b_data) + 3466 (desiredpages << PAGE_SHIFT), 3467 (bp->b_npages - desiredpages)); 3468 } else 3469 BUF_CHECK_UNMAPPED(bp); 3470 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 3471 for (i = desiredpages; i < bp->b_npages; i++) { 3472 /* 3473 * the page is not freed here -- it 3474 * is the responsibility of 3475 * vnode_pager_setsize 3476 */ 3477 m = bp->b_pages[i]; 3478 KASSERT(m != bogus_page, 3479 ("allocbuf: bogus page found")); 3480 while (vm_page_sleep_if_busy(m, 3481 "biodep")) 3482 continue; 3483 3484 bp->b_pages[i] = NULL; 3485 vm_page_lock(m); 3486 vm_page_unwire(m, PQ_INACTIVE); 3487 vm_page_unlock(m); 3488 } 3489 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 3490 bp->b_npages = desiredpages; 3491 } 3492 } else if (size > bp->b_bcount) { 3493 /* 3494 * We are growing the buffer, possibly in a 3495 * byte-granular fashion. 3496 */ 3497 vm_object_t obj; 3498 vm_offset_t toff; 3499 vm_offset_t tinc; 3500 3501 /* 3502 * Step 1, bring in the VM pages from the object, 3503 * allocating them if necessary. We must clear 3504 * B_CACHE if these pages are not valid for the 3505 * range covered by the buffer. 3506 */ 3507 3508 obj = bp->b_bufobj->bo_object; 3509 3510 VM_OBJECT_WLOCK(obj); 3511 while (bp->b_npages < desiredpages) { 3512 vm_page_t m; 3513 3514 /* 3515 * We must allocate system pages since blocking 3516 * here could interfere with paging I/O, no 3517 * matter which process we are. 3518 * 3519 * Only exclusive busy can be tested here. 3520 * Blocking on shared busy might lead to 3521 * deadlocks once allocbuf() is called after 3522 * pages are vfs_busy_pages(). 3523 */ 3524 m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) + 3525 bp->b_npages, VM_ALLOC_NOBUSY | 3526 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED | 3527 VM_ALLOC_IGN_SBUSY | 3528 VM_ALLOC_COUNT(desiredpages - bp->b_npages)); 3529 if (m->valid == 0) 3530 bp->b_flags &= ~B_CACHE; 3531 bp->b_pages[bp->b_npages] = m; 3532 ++bp->b_npages; 3533 } 3534 3535 /* 3536 * Step 2. We've loaded the pages into the buffer, 3537 * we have to figure out if we can still have B_CACHE 3538 * set. Note that B_CACHE is set according to the 3539 * byte-granular range ( bcount and size ), new the 3540 * aligned range ( newbsize ). 3541 * 3542 * The VM test is against m->valid, which is DEV_BSIZE 3543 * aligned. Needless to say, the validity of the data 3544 * needs to also be DEV_BSIZE aligned. Note that this 3545 * fails with NFS if the server or some other client 3546 * extends the file's EOF. If our buffer is resized, 3547 * B_CACHE may remain set! XXX 3548 */ 3549 3550 toff = bp->b_bcount; 3551 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 3552 3553 while ((bp->b_flags & B_CACHE) && toff < size) { 3554 vm_pindex_t pi; 3555 3556 if (tinc > (size - toff)) 3557 tinc = size - toff; 3558 3559 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 3560 PAGE_SHIFT; 3561 3562 vfs_buf_test_cache( 3563 bp, 3564 bp->b_offset, 3565 toff, 3566 tinc, 3567 bp->b_pages[pi] 3568 ); 3569 toff += tinc; 3570 tinc = PAGE_SIZE; 3571 } 3572 VM_OBJECT_WUNLOCK(obj); 3573 3574 /* 3575 * Step 3, fixup the KVM pmap. 3576 */ 3577 if ((bp->b_flags & B_UNMAPPED) == 0) 3578 bpmap_qenter(bp); 3579 else 3580 BUF_CHECK_UNMAPPED(bp); 3581 } 3582 } 3583 if (newbsize < bp->b_bufsize) 3584 bufspacewakeup(); 3585 bp->b_bufsize = newbsize; /* actual buffer allocation */ 3586 bp->b_bcount = size; /* requested buffer size */ 3587 return 1; 3588 } 3589 3590 extern int inflight_transient_maps; 3591 3592 void 3593 biodone(struct bio *bp) 3594 { 3595 struct mtx *mtxp; 3596 void (*done)(struct bio *); 3597 vm_offset_t start, end; 3598 3599 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) { 3600 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING; 3601 bp->bio_flags |= BIO_UNMAPPED; 3602 start = trunc_page((vm_offset_t)bp->bio_data); 3603 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length); 3604 pmap_qremove(start, OFF_TO_IDX(end - start)); 3605 vmem_free(transient_arena, start, end - start); 3606 atomic_add_int(&inflight_transient_maps, -1); 3607 } 3608 done = bp->bio_done; 3609 if (done == NULL) { 3610 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3611 mtx_lock(mtxp); 3612 bp->bio_flags |= BIO_DONE; 3613 wakeup(bp); 3614 mtx_unlock(mtxp); 3615 } else { 3616 bp->bio_flags |= BIO_DONE; 3617 done(bp); 3618 } 3619 } 3620 3621 /* 3622 * Wait for a BIO to finish. 3623 */ 3624 int 3625 biowait(struct bio *bp, const char *wchan) 3626 { 3627 struct mtx *mtxp; 3628 3629 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3630 mtx_lock(mtxp); 3631 while ((bp->bio_flags & BIO_DONE) == 0) 3632 msleep(bp, mtxp, PRIBIO, wchan, 0); 3633 mtx_unlock(mtxp); 3634 if (bp->bio_error != 0) 3635 return (bp->bio_error); 3636 if (!(bp->bio_flags & BIO_ERROR)) 3637 return (0); 3638 return (EIO); 3639 } 3640 3641 void 3642 biofinish(struct bio *bp, struct devstat *stat, int error) 3643 { 3644 3645 if (error) { 3646 bp->bio_error = error; 3647 bp->bio_flags |= BIO_ERROR; 3648 } 3649 if (stat != NULL) 3650 devstat_end_transaction_bio(stat, bp); 3651 biodone(bp); 3652 } 3653 3654 /* 3655 * bufwait: 3656 * 3657 * Wait for buffer I/O completion, returning error status. The buffer 3658 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3659 * error and cleared. 3660 */ 3661 int 3662 bufwait(struct buf *bp) 3663 { 3664 if (bp->b_iocmd == BIO_READ) 3665 bwait(bp, PRIBIO, "biord"); 3666 else 3667 bwait(bp, PRIBIO, "biowr"); 3668 if (bp->b_flags & B_EINTR) { 3669 bp->b_flags &= ~B_EINTR; 3670 return (EINTR); 3671 } 3672 if (bp->b_ioflags & BIO_ERROR) { 3673 return (bp->b_error ? bp->b_error : EIO); 3674 } else { 3675 return (0); 3676 } 3677 } 3678 3679 /* 3680 * Call back function from struct bio back up to struct buf. 3681 */ 3682 static void 3683 bufdonebio(struct bio *bip) 3684 { 3685 struct buf *bp; 3686 3687 bp = bip->bio_caller2; 3688 bp->b_resid = bip->bio_resid; 3689 bp->b_ioflags = bip->bio_flags; 3690 bp->b_error = bip->bio_error; 3691 if (bp->b_error) 3692 bp->b_ioflags |= BIO_ERROR; 3693 bufdone(bp); 3694 g_destroy_bio(bip); 3695 } 3696 3697 void 3698 dev_strategy(struct cdev *dev, struct buf *bp) 3699 { 3700 struct cdevsw *csw; 3701 int ref; 3702 3703 KASSERT(dev->si_refcount > 0, 3704 ("dev_strategy on un-referenced struct cdev *(%s) %p", 3705 devtoname(dev), dev)); 3706 3707 csw = dev_refthread(dev, &ref); 3708 dev_strategy_csw(dev, csw, bp); 3709 dev_relthread(dev, ref); 3710 } 3711 3712 void 3713 dev_strategy_csw(struct cdev *dev, struct cdevsw *csw, struct buf *bp) 3714 { 3715 struct bio *bip; 3716 3717 KASSERT(bp->b_iocmd == BIO_READ || bp->b_iocmd == BIO_WRITE, 3718 ("b_iocmd botch")); 3719 KASSERT(((dev->si_flags & SI_ETERNAL) != 0 && csw != NULL) || 3720 dev->si_threadcount > 0, 3721 ("dev_strategy_csw threadcount cdev *(%s) %p", devtoname(dev), 3722 dev)); 3723 if (csw == NULL) { 3724 bp->b_error = ENXIO; 3725 bp->b_ioflags = BIO_ERROR; 3726 bufdone(bp); 3727 return; 3728 } 3729 for (;;) { 3730 bip = g_new_bio(); 3731 if (bip != NULL) 3732 break; 3733 /* Try again later */ 3734 tsleep(&bp, PRIBIO, "dev_strat", hz/10); 3735 } 3736 bip->bio_cmd = bp->b_iocmd; 3737 bip->bio_offset = bp->b_iooffset; 3738 bip->bio_length = bp->b_bcount; 3739 bip->bio_bcount = bp->b_bcount; /* XXX: remove */ 3740 bdata2bio(bp, bip); 3741 bip->bio_done = bufdonebio; 3742 bip->bio_caller2 = bp; 3743 bip->bio_dev = dev; 3744 (*csw->d_strategy)(bip); 3745 } 3746 3747 /* 3748 * bufdone: 3749 * 3750 * Finish I/O on a buffer, optionally calling a completion function. 3751 * This is usually called from an interrupt so process blocking is 3752 * not allowed. 3753 * 3754 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3755 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3756 * assuming B_INVAL is clear. 3757 * 3758 * For the VMIO case, we set B_CACHE if the op was a read and no 3759 * read error occured, or if the op was a write. B_CACHE is never 3760 * set if the buffer is invalid or otherwise uncacheable. 3761 * 3762 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3763 * initiator to leave B_INVAL set to brelse the buffer out of existance 3764 * in the biodone routine. 3765 */ 3766 void 3767 bufdone(struct buf *bp) 3768 { 3769 struct bufobj *dropobj; 3770 void (*biodone)(struct buf *); 3771 3772 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 3773 dropobj = NULL; 3774 3775 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 3776 BUF_ASSERT_HELD(bp); 3777 3778 runningbufwakeup(bp); 3779 if (bp->b_iocmd == BIO_WRITE) 3780 dropobj = bp->b_bufobj; 3781 /* call optional completion function if requested */ 3782 if (bp->b_iodone != NULL) { 3783 biodone = bp->b_iodone; 3784 bp->b_iodone = NULL; 3785 (*biodone) (bp); 3786 if (dropobj) 3787 bufobj_wdrop(dropobj); 3788 return; 3789 } 3790 3791 bufdone_finish(bp); 3792 3793 if (dropobj) 3794 bufobj_wdrop(dropobj); 3795 } 3796 3797 void 3798 bufdone_finish(struct buf *bp) 3799 { 3800 BUF_ASSERT_HELD(bp); 3801 3802 if (!LIST_EMPTY(&bp->b_dep)) 3803 buf_complete(bp); 3804 3805 if (bp->b_flags & B_VMIO) { 3806 vm_ooffset_t foff; 3807 vm_page_t m; 3808 vm_object_t obj; 3809 struct vnode *vp; 3810 int bogus, i, iosize; 3811 3812 obj = bp->b_bufobj->bo_object; 3813 KASSERT(obj->paging_in_progress >= bp->b_npages, 3814 ("biodone_finish: paging in progress(%d) < b_npages(%d)", 3815 obj->paging_in_progress, bp->b_npages)); 3816 3817 vp = bp->b_vp; 3818 KASSERT(vp->v_holdcnt > 0, 3819 ("biodone_finish: vnode %p has zero hold count", vp)); 3820 KASSERT(vp->v_object != NULL, 3821 ("biodone_finish: vnode %p has no vm_object", vp)); 3822 3823 foff = bp->b_offset; 3824 KASSERT(bp->b_offset != NOOFFSET, 3825 ("biodone_finish: bp %p has no buffer offset", bp)); 3826 3827 /* 3828 * Set B_CACHE if the op was a normal read and no error 3829 * occured. B_CACHE is set for writes in the b*write() 3830 * routines. 3831 */ 3832 iosize = bp->b_bcount - bp->b_resid; 3833 if (bp->b_iocmd == BIO_READ && 3834 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 3835 !(bp->b_ioflags & BIO_ERROR)) { 3836 bp->b_flags |= B_CACHE; 3837 } 3838 bogus = 0; 3839 VM_OBJECT_WLOCK(obj); 3840 for (i = 0; i < bp->b_npages; i++) { 3841 int bogusflag = 0; 3842 int resid; 3843 3844 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 3845 if (resid > iosize) 3846 resid = iosize; 3847 3848 /* 3849 * cleanup bogus pages, restoring the originals 3850 */ 3851 m = bp->b_pages[i]; 3852 if (m == bogus_page) { 3853 bogus = bogusflag = 1; 3854 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3855 if (m == NULL) 3856 panic("biodone: page disappeared!"); 3857 bp->b_pages[i] = m; 3858 } 3859 KASSERT(OFF_TO_IDX(foff) == m->pindex, 3860 ("biodone_finish: foff(%jd)/pindex(%ju) mismatch", 3861 (intmax_t)foff, (uintmax_t)m->pindex)); 3862 3863 /* 3864 * In the write case, the valid and clean bits are 3865 * already changed correctly ( see bdwrite() ), so we 3866 * only need to do this here in the read case. 3867 */ 3868 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 3869 KASSERT((m->dirty & vm_page_bits(foff & 3870 PAGE_MASK, resid)) == 0, ("bufdone_finish:" 3871 " page %p has unexpected dirty bits", m)); 3872 vfs_page_set_valid(bp, foff, m); 3873 } 3874 3875 vm_page_sunbusy(m); 3876 vm_object_pip_subtract(obj, 1); 3877 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3878 iosize -= resid; 3879 } 3880 vm_object_pip_wakeupn(obj, 0); 3881 VM_OBJECT_WUNLOCK(obj); 3882 if (bogus && (bp->b_flags & B_UNMAPPED) == 0) { 3883 BUF_CHECK_MAPPED(bp); 3884 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3885 bp->b_pages, bp->b_npages); 3886 } 3887 } 3888 3889 /* 3890 * For asynchronous completions, release the buffer now. The brelse 3891 * will do a wakeup there if necessary - so no need to do a wakeup 3892 * here in the async case. The sync case always needs to do a wakeup. 3893 */ 3894 3895 if (bp->b_flags & B_ASYNC) { 3896 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 3897 brelse(bp); 3898 else 3899 bqrelse(bp); 3900 } else 3901 bdone(bp); 3902 } 3903 3904 /* 3905 * This routine is called in lieu of iodone in the case of 3906 * incomplete I/O. This keeps the busy status for pages 3907 * consistant. 3908 */ 3909 void 3910 vfs_unbusy_pages(struct buf *bp) 3911 { 3912 int i; 3913 vm_object_t obj; 3914 vm_page_t m; 3915 3916 runningbufwakeup(bp); 3917 if (!(bp->b_flags & B_VMIO)) 3918 return; 3919 3920 obj = bp->b_bufobj->bo_object; 3921 VM_OBJECT_WLOCK(obj); 3922 for (i = 0; i < bp->b_npages; i++) { 3923 m = bp->b_pages[i]; 3924 if (m == bogus_page) { 3925 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 3926 if (!m) 3927 panic("vfs_unbusy_pages: page missing\n"); 3928 bp->b_pages[i] = m; 3929 if ((bp->b_flags & B_UNMAPPED) == 0) { 3930 BUF_CHECK_MAPPED(bp); 3931 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3932 bp->b_pages, bp->b_npages); 3933 } else 3934 BUF_CHECK_UNMAPPED(bp); 3935 } 3936 vm_object_pip_subtract(obj, 1); 3937 vm_page_sunbusy(m); 3938 } 3939 vm_object_pip_wakeupn(obj, 0); 3940 VM_OBJECT_WUNLOCK(obj); 3941 } 3942 3943 /* 3944 * vfs_page_set_valid: 3945 * 3946 * Set the valid bits in a page based on the supplied offset. The 3947 * range is restricted to the buffer's size. 3948 * 3949 * This routine is typically called after a read completes. 3950 */ 3951 static void 3952 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3953 { 3954 vm_ooffset_t eoff; 3955 3956 /* 3957 * Compute the end offset, eoff, such that [off, eoff) does not span a 3958 * page boundary and eoff is not greater than the end of the buffer. 3959 * The end of the buffer, in this case, is our file EOF, not the 3960 * allocation size of the buffer. 3961 */ 3962 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 3963 if (eoff > bp->b_offset + bp->b_bcount) 3964 eoff = bp->b_offset + bp->b_bcount; 3965 3966 /* 3967 * Set valid range. This is typically the entire buffer and thus the 3968 * entire page. 3969 */ 3970 if (eoff > off) 3971 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off); 3972 } 3973 3974 /* 3975 * vfs_page_set_validclean: 3976 * 3977 * Set the valid bits and clear the dirty bits in a page based on the 3978 * supplied offset. The range is restricted to the buffer's size. 3979 */ 3980 static void 3981 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3982 { 3983 vm_ooffset_t soff, eoff; 3984 3985 /* 3986 * Start and end offsets in buffer. eoff - soff may not cross a 3987 * page boundry or cross the end of the buffer. The end of the 3988 * buffer, in this case, is our file EOF, not the allocation size 3989 * of the buffer. 3990 */ 3991 soff = off; 3992 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3993 if (eoff > bp->b_offset + bp->b_bcount) 3994 eoff = bp->b_offset + bp->b_bcount; 3995 3996 /* 3997 * Set valid range. This is typically the entire buffer and thus the 3998 * entire page. 3999 */ 4000 if (eoff > soff) { 4001 vm_page_set_validclean( 4002 m, 4003 (vm_offset_t) (soff & PAGE_MASK), 4004 (vm_offset_t) (eoff - soff) 4005 ); 4006 } 4007 } 4008 4009 /* 4010 * Ensure that all buffer pages are not exclusive busied. If any page is 4011 * exclusive busy, drain it. 4012 */ 4013 void 4014 vfs_drain_busy_pages(struct buf *bp) 4015 { 4016 vm_page_t m; 4017 int i, last_busied; 4018 4019 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object); 4020 last_busied = 0; 4021 for (i = 0; i < bp->b_npages; i++) { 4022 m = bp->b_pages[i]; 4023 if (vm_page_xbusied(m)) { 4024 for (; last_busied < i; last_busied++) 4025 vm_page_sbusy(bp->b_pages[last_busied]); 4026 while (vm_page_xbusied(m)) { 4027 vm_page_lock(m); 4028 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4029 vm_page_busy_sleep(m, "vbpage"); 4030 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4031 } 4032 } 4033 } 4034 for (i = 0; i < last_busied; i++) 4035 vm_page_sunbusy(bp->b_pages[i]); 4036 } 4037 4038 /* 4039 * This routine is called before a device strategy routine. 4040 * It is used to tell the VM system that paging I/O is in 4041 * progress, and treat the pages associated with the buffer 4042 * almost as being exclusive busy. Also the object paging_in_progress 4043 * flag is handled to make sure that the object doesn't become 4044 * inconsistant. 4045 * 4046 * Since I/O has not been initiated yet, certain buffer flags 4047 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 4048 * and should be ignored. 4049 */ 4050 void 4051 vfs_busy_pages(struct buf *bp, int clear_modify) 4052 { 4053 int i, bogus; 4054 vm_object_t obj; 4055 vm_ooffset_t foff; 4056 vm_page_t m; 4057 4058 if (!(bp->b_flags & B_VMIO)) 4059 return; 4060 4061 obj = bp->b_bufobj->bo_object; 4062 foff = bp->b_offset; 4063 KASSERT(bp->b_offset != NOOFFSET, 4064 ("vfs_busy_pages: no buffer offset")); 4065 VM_OBJECT_WLOCK(obj); 4066 vfs_drain_busy_pages(bp); 4067 if (bp->b_bufsize != 0) 4068 vfs_setdirty_locked_object(bp); 4069 bogus = 0; 4070 for (i = 0; i < bp->b_npages; i++) { 4071 m = bp->b_pages[i]; 4072 4073 if ((bp->b_flags & B_CLUSTER) == 0) { 4074 vm_object_pip_add(obj, 1); 4075 vm_page_sbusy(m); 4076 } 4077 /* 4078 * When readying a buffer for a read ( i.e 4079 * clear_modify == 0 ), it is important to do 4080 * bogus_page replacement for valid pages in 4081 * partially instantiated buffers. Partially 4082 * instantiated buffers can, in turn, occur when 4083 * reconstituting a buffer from its VM backing store 4084 * base. We only have to do this if B_CACHE is 4085 * clear ( which causes the I/O to occur in the 4086 * first place ). The replacement prevents the read 4087 * I/O from overwriting potentially dirty VM-backed 4088 * pages. XXX bogus page replacement is, uh, bogus. 4089 * It may not work properly with small-block devices. 4090 * We need to find a better way. 4091 */ 4092 if (clear_modify) { 4093 pmap_remove_write(m); 4094 vfs_page_set_validclean(bp, foff, m); 4095 } else if (m->valid == VM_PAGE_BITS_ALL && 4096 (bp->b_flags & B_CACHE) == 0) { 4097 bp->b_pages[i] = bogus_page; 4098 bogus++; 4099 } 4100 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4101 } 4102 VM_OBJECT_WUNLOCK(obj); 4103 if (bogus && (bp->b_flags & B_UNMAPPED) == 0) { 4104 BUF_CHECK_MAPPED(bp); 4105 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4106 bp->b_pages, bp->b_npages); 4107 } 4108 } 4109 4110 /* 4111 * vfs_bio_set_valid: 4112 * 4113 * Set the range within the buffer to valid. The range is 4114 * relative to the beginning of the buffer, b_offset. Note that 4115 * b_offset itself may be offset from the beginning of the first 4116 * page. 4117 */ 4118 void 4119 vfs_bio_set_valid(struct buf *bp, int base, int size) 4120 { 4121 int i, n; 4122 vm_page_t m; 4123 4124 if (!(bp->b_flags & B_VMIO)) 4125 return; 4126 4127 /* 4128 * Fixup base to be relative to beginning of first page. 4129 * Set initial n to be the maximum number of bytes in the 4130 * first page that can be validated. 4131 */ 4132 base += (bp->b_offset & PAGE_MASK); 4133 n = PAGE_SIZE - (base & PAGE_MASK); 4134 4135 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4136 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4137 m = bp->b_pages[i]; 4138 if (n > size) 4139 n = size; 4140 vm_page_set_valid_range(m, base & PAGE_MASK, n); 4141 base += n; 4142 size -= n; 4143 n = PAGE_SIZE; 4144 } 4145 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4146 } 4147 4148 /* 4149 * vfs_bio_clrbuf: 4150 * 4151 * If the specified buffer is a non-VMIO buffer, clear the entire 4152 * buffer. If the specified buffer is a VMIO buffer, clear and 4153 * validate only the previously invalid portions of the buffer. 4154 * This routine essentially fakes an I/O, so we need to clear 4155 * BIO_ERROR and B_INVAL. 4156 * 4157 * Note that while we only theoretically need to clear through b_bcount, 4158 * we go ahead and clear through b_bufsize. 4159 */ 4160 void 4161 vfs_bio_clrbuf(struct buf *bp) 4162 { 4163 int i, j, mask, sa, ea, slide; 4164 4165 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 4166 clrbuf(bp); 4167 return; 4168 } 4169 bp->b_flags &= ~B_INVAL; 4170 bp->b_ioflags &= ~BIO_ERROR; 4171 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4172 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 4173 (bp->b_offset & PAGE_MASK) == 0) { 4174 if (bp->b_pages[0] == bogus_page) 4175 goto unlock; 4176 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 4177 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object); 4178 if ((bp->b_pages[0]->valid & mask) == mask) 4179 goto unlock; 4180 if ((bp->b_pages[0]->valid & mask) == 0) { 4181 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize); 4182 bp->b_pages[0]->valid |= mask; 4183 goto unlock; 4184 } 4185 } 4186 sa = bp->b_offset & PAGE_MASK; 4187 slide = 0; 4188 for (i = 0; i < bp->b_npages; i++, sa = 0) { 4189 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize); 4190 ea = slide & PAGE_MASK; 4191 if (ea == 0) 4192 ea = PAGE_SIZE; 4193 if (bp->b_pages[i] == bogus_page) 4194 continue; 4195 j = sa / DEV_BSIZE; 4196 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 4197 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object); 4198 if ((bp->b_pages[i]->valid & mask) == mask) 4199 continue; 4200 if ((bp->b_pages[i]->valid & mask) == 0) 4201 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa); 4202 else { 4203 for (; sa < ea; sa += DEV_BSIZE, j++) { 4204 if ((bp->b_pages[i]->valid & (1 << j)) == 0) { 4205 pmap_zero_page_area(bp->b_pages[i], 4206 sa, DEV_BSIZE); 4207 } 4208 } 4209 } 4210 bp->b_pages[i]->valid |= mask; 4211 } 4212 unlock: 4213 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4214 bp->b_resid = 0; 4215 } 4216 4217 void 4218 vfs_bio_bzero_buf(struct buf *bp, int base, int size) 4219 { 4220 vm_page_t m; 4221 int i, n; 4222 4223 if ((bp->b_flags & B_UNMAPPED) == 0) { 4224 BUF_CHECK_MAPPED(bp); 4225 bzero(bp->b_data + base, size); 4226 } else { 4227 BUF_CHECK_UNMAPPED(bp); 4228 n = PAGE_SIZE - (base & PAGE_MASK); 4229 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4230 m = bp->b_pages[i]; 4231 if (n > size) 4232 n = size; 4233 pmap_zero_page_area(m, base & PAGE_MASK, n); 4234 base += n; 4235 size -= n; 4236 n = PAGE_SIZE; 4237 } 4238 } 4239 } 4240 4241 /* 4242 * vm_hold_load_pages and vm_hold_free_pages get pages into 4243 * a buffers address space. The pages are anonymous and are 4244 * not associated with a file object. 4245 */ 4246 static void 4247 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4248 { 4249 vm_offset_t pg; 4250 vm_page_t p; 4251 int index; 4252 4253 BUF_CHECK_MAPPED(bp); 4254 4255 to = round_page(to); 4256 from = round_page(from); 4257 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4258 4259 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 4260 tryagain: 4261 /* 4262 * note: must allocate system pages since blocking here 4263 * could interfere with paging I/O, no matter which 4264 * process we are. 4265 */ 4266 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ | 4267 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT)); 4268 if (p == NULL) { 4269 VM_WAIT; 4270 goto tryagain; 4271 } 4272 pmap_qenter(pg, &p, 1); 4273 bp->b_pages[index] = p; 4274 } 4275 bp->b_npages = index; 4276 } 4277 4278 /* Return pages associated with this buf to the vm system */ 4279 static void 4280 vm_hold_free_pages(struct buf *bp, int newbsize) 4281 { 4282 vm_offset_t from; 4283 vm_page_t p; 4284 int index, newnpages; 4285 4286 BUF_CHECK_MAPPED(bp); 4287 4288 from = round_page((vm_offset_t)bp->b_data + newbsize); 4289 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4290 if (bp->b_npages > newnpages) 4291 pmap_qremove(from, bp->b_npages - newnpages); 4292 for (index = newnpages; index < bp->b_npages; index++) { 4293 p = bp->b_pages[index]; 4294 bp->b_pages[index] = NULL; 4295 if (vm_page_sbusied(p)) 4296 printf("vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 4297 (intmax_t)bp->b_blkno, (intmax_t)bp->b_lblkno); 4298 p->wire_count--; 4299 vm_page_free(p); 4300 atomic_subtract_int(&vm_cnt.v_wire_count, 1); 4301 } 4302 bp->b_npages = newnpages; 4303 } 4304 4305 /* 4306 * Map an IO request into kernel virtual address space. 4307 * 4308 * All requests are (re)mapped into kernel VA space. 4309 * Notice that we use b_bufsize for the size of the buffer 4310 * to be mapped. b_bcount might be modified by the driver. 4311 * 4312 * Note that even if the caller determines that the address space should 4313 * be valid, a race or a smaller-file mapped into a larger space may 4314 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 4315 * check the return value. 4316 */ 4317 int 4318 vmapbuf(struct buf *bp, int mapbuf) 4319 { 4320 caddr_t kva; 4321 vm_prot_t prot; 4322 int pidx; 4323 4324 if (bp->b_bufsize < 0) 4325 return (-1); 4326 prot = VM_PROT_READ; 4327 if (bp->b_iocmd == BIO_READ) 4328 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 4329 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 4330 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages, 4331 btoc(MAXPHYS))) < 0) 4332 return (-1); 4333 bp->b_npages = pidx; 4334 if (mapbuf || !unmapped_buf_allowed) { 4335 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx); 4336 kva = bp->b_saveaddr; 4337 bp->b_saveaddr = bp->b_data; 4338 bp->b_data = kva + (((vm_offset_t)bp->b_data) & PAGE_MASK); 4339 bp->b_flags &= ~B_UNMAPPED; 4340 } else { 4341 bp->b_flags |= B_UNMAPPED; 4342 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK; 4343 bp->b_saveaddr = bp->b_data; 4344 bp->b_data = unmapped_buf; 4345 } 4346 return(0); 4347 } 4348 4349 /* 4350 * Free the io map PTEs associated with this IO operation. 4351 * We also invalidate the TLB entries and restore the original b_addr. 4352 */ 4353 void 4354 vunmapbuf(struct buf *bp) 4355 { 4356 int npages; 4357 4358 npages = bp->b_npages; 4359 if (bp->b_flags & B_UNMAPPED) 4360 bp->b_flags &= ~B_UNMAPPED; 4361 else 4362 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 4363 vm_page_unhold_pages(bp->b_pages, npages); 4364 4365 bp->b_data = bp->b_saveaddr; 4366 } 4367 4368 void 4369 bdone(struct buf *bp) 4370 { 4371 struct mtx *mtxp; 4372 4373 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4374 mtx_lock(mtxp); 4375 bp->b_flags |= B_DONE; 4376 wakeup(bp); 4377 mtx_unlock(mtxp); 4378 } 4379 4380 void 4381 bwait(struct buf *bp, u_char pri, const char *wchan) 4382 { 4383 struct mtx *mtxp; 4384 4385 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4386 mtx_lock(mtxp); 4387 while ((bp->b_flags & B_DONE) == 0) 4388 msleep(bp, mtxp, pri, wchan, 0); 4389 mtx_unlock(mtxp); 4390 } 4391 4392 int 4393 bufsync(struct bufobj *bo, int waitfor) 4394 { 4395 4396 return (VOP_FSYNC(bo->__bo_vnode, waitfor, curthread)); 4397 } 4398 4399 void 4400 bufstrategy(struct bufobj *bo, struct buf *bp) 4401 { 4402 int i = 0; 4403 struct vnode *vp; 4404 4405 vp = bp->b_vp; 4406 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 4407 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 4408 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 4409 i = VOP_STRATEGY(vp, bp); 4410 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 4411 } 4412 4413 void 4414 bufobj_wrefl(struct bufobj *bo) 4415 { 4416 4417 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4418 ASSERT_BO_WLOCKED(bo); 4419 bo->bo_numoutput++; 4420 } 4421 4422 void 4423 bufobj_wref(struct bufobj *bo) 4424 { 4425 4426 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4427 BO_LOCK(bo); 4428 bo->bo_numoutput++; 4429 BO_UNLOCK(bo); 4430 } 4431 4432 void 4433 bufobj_wdrop(struct bufobj *bo) 4434 { 4435 4436 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 4437 BO_LOCK(bo); 4438 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 4439 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 4440 bo->bo_flag &= ~BO_WWAIT; 4441 wakeup(&bo->bo_numoutput); 4442 } 4443 BO_UNLOCK(bo); 4444 } 4445 4446 int 4447 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 4448 { 4449 int error; 4450 4451 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 4452 ASSERT_BO_WLOCKED(bo); 4453 error = 0; 4454 while (bo->bo_numoutput) { 4455 bo->bo_flag |= BO_WWAIT; 4456 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo), 4457 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 4458 if (error) 4459 break; 4460 } 4461 return (error); 4462 } 4463 4464 void 4465 bpin(struct buf *bp) 4466 { 4467 struct mtx *mtxp; 4468 4469 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4470 mtx_lock(mtxp); 4471 bp->b_pin_count++; 4472 mtx_unlock(mtxp); 4473 } 4474 4475 void 4476 bunpin(struct buf *bp) 4477 { 4478 struct mtx *mtxp; 4479 4480 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4481 mtx_lock(mtxp); 4482 if (--bp->b_pin_count == 0) 4483 wakeup(bp); 4484 mtx_unlock(mtxp); 4485 } 4486 4487 void 4488 bunpin_wait(struct buf *bp) 4489 { 4490 struct mtx *mtxp; 4491 4492 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4493 mtx_lock(mtxp); 4494 while (bp->b_pin_count > 0) 4495 msleep(bp, mtxp, PRIBIO, "bwunpin", 0); 4496 mtx_unlock(mtxp); 4497 } 4498 4499 /* 4500 * Set bio_data or bio_ma for struct bio from the struct buf. 4501 */ 4502 void 4503 bdata2bio(struct buf *bp, struct bio *bip) 4504 { 4505 4506 if ((bp->b_flags & B_UNMAPPED) != 0) { 4507 KASSERT(unmapped_buf_allowed, ("unmapped")); 4508 bip->bio_ma = bp->b_pages; 4509 bip->bio_ma_n = bp->b_npages; 4510 bip->bio_data = unmapped_buf; 4511 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 4512 bip->bio_flags |= BIO_UNMAPPED; 4513 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) / 4514 PAGE_SIZE == bp->b_npages, 4515 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset, 4516 (long long)bip->bio_length, bip->bio_ma_n)); 4517 } else { 4518 bip->bio_data = bp->b_data; 4519 bip->bio_ma = NULL; 4520 } 4521 } 4522 4523 #include "opt_ddb.h" 4524 #ifdef DDB 4525 #include <ddb/ddb.h> 4526 4527 /* DDB command to show buffer data */ 4528 DB_SHOW_COMMAND(buffer, db_show_buffer) 4529 { 4530 /* get args */ 4531 struct buf *bp = (struct buf *)addr; 4532 4533 if (!have_addr) { 4534 db_printf("usage: show buffer <addr>\n"); 4535 return; 4536 } 4537 4538 db_printf("buf at %p\n", bp); 4539 db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n", 4540 (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags, 4541 PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS); 4542 db_printf( 4543 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 4544 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, " 4545 "b_dep = %p\n", 4546 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 4547 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 4548 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first); 4549 if (bp->b_npages) { 4550 int i; 4551 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 4552 for (i = 0; i < bp->b_npages; i++) { 4553 vm_page_t m; 4554 m = bp->b_pages[i]; 4555 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 4556 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 4557 if ((i + 1) < bp->b_npages) 4558 db_printf(","); 4559 } 4560 db_printf("\n"); 4561 } 4562 db_printf(" "); 4563 BUF_LOCKPRINTINFO(bp); 4564 } 4565 4566 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 4567 { 4568 struct buf *bp; 4569 int i; 4570 4571 for (i = 0; i < nbuf; i++) { 4572 bp = &buf[i]; 4573 if (BUF_ISLOCKED(bp)) { 4574 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4575 db_printf("\n"); 4576 } 4577 } 4578 } 4579 4580 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 4581 { 4582 struct vnode *vp; 4583 struct buf *bp; 4584 4585 if (!have_addr) { 4586 db_printf("usage: show vnodebufs <addr>\n"); 4587 return; 4588 } 4589 vp = (struct vnode *)addr; 4590 db_printf("Clean buffers:\n"); 4591 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 4592 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4593 db_printf("\n"); 4594 } 4595 db_printf("Dirty buffers:\n"); 4596 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 4597 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4598 db_printf("\n"); 4599 } 4600 } 4601 4602 DB_COMMAND(countfreebufs, db_coundfreebufs) 4603 { 4604 struct buf *bp; 4605 int i, used = 0, nfree = 0; 4606 4607 if (have_addr) { 4608 db_printf("usage: countfreebufs\n"); 4609 return; 4610 } 4611 4612 for (i = 0; i < nbuf; i++) { 4613 bp = &buf[i]; 4614 if ((bp->b_flags & B_INFREECNT) != 0) 4615 nfree++; 4616 else 4617 used++; 4618 } 4619 4620 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 4621 nfree + used); 4622 db_printf("numfreebuffers is %d\n", numfreebuffers); 4623 } 4624 #endif /* DDB */ 4625