1 /*- 2 * Copyright (c) 2004 Poul-Henning Kamp 3 * Copyright (c) 1994,1997 John S. Dyson 4 * Copyright (c) 2013 The FreeBSD Foundation 5 * All rights reserved. 6 * 7 * Portions of this software were developed by Konstantin Belousov 8 * under sponsorship from the FreeBSD Foundation. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 /* 33 * this file contains a new buffer I/O scheme implementing a coherent 34 * VM object and buffer cache scheme. Pains have been taken to make 35 * sure that the performance degradation associated with schemes such 36 * as this is not realized. 37 * 38 * Author: John S. Dyson 39 * Significant help during the development and debugging phases 40 * had been provided by David Greenman, also of the FreeBSD core team. 41 * 42 * see man buf(9) for more info. 43 */ 44 45 #include <sys/cdefs.h> 46 __FBSDID("$FreeBSD$"); 47 48 #include <sys/param.h> 49 #include <sys/systm.h> 50 #include <sys/bio.h> 51 #include <sys/conf.h> 52 #include <sys/buf.h> 53 #include <sys/devicestat.h> 54 #include <sys/eventhandler.h> 55 #include <sys/fail.h> 56 #include <sys/limits.h> 57 #include <sys/lock.h> 58 #include <sys/malloc.h> 59 #include <sys/mount.h> 60 #include <sys/mutex.h> 61 #include <sys/kernel.h> 62 #include <sys/kthread.h> 63 #include <sys/proc.h> 64 #include <sys/resourcevar.h> 65 #include <sys/rwlock.h> 66 #include <sys/sysctl.h> 67 #include <sys/vmem.h> 68 #include <sys/vmmeter.h> 69 #include <sys/vnode.h> 70 #include <geom/geom.h> 71 #include <vm/vm.h> 72 #include <vm/vm_param.h> 73 #include <vm/vm_kern.h> 74 #include <vm/vm_pageout.h> 75 #include <vm/vm_page.h> 76 #include <vm/vm_object.h> 77 #include <vm/vm_extern.h> 78 #include <vm/vm_map.h> 79 #include "opt_compat.h" 80 #include "opt_swap.h" 81 82 static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer"); 83 84 struct bio_ops bioops; /* I/O operation notification */ 85 86 struct buf_ops buf_ops_bio = { 87 .bop_name = "buf_ops_bio", 88 .bop_write = bufwrite, 89 .bop_strategy = bufstrategy, 90 .bop_sync = bufsync, 91 .bop_bdflush = bufbdflush, 92 }; 93 94 /* 95 * XXX buf is global because kern_shutdown.c and ffs_checkoverlap has 96 * carnal knowledge of buffers. This knowledge should be moved to vfs_bio.c. 97 */ 98 struct buf *buf; /* buffer header pool */ 99 caddr_t unmapped_buf; 100 101 /* Used below and for softdep flushing threads in ufs/ffs/ffs_softdep.c */ 102 struct proc *bufdaemonproc; 103 104 static int inmem(struct vnode *vp, daddr_t blkno); 105 static void vm_hold_free_pages(struct buf *bp, int newbsize); 106 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from, 107 vm_offset_t to); 108 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m); 109 static void vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, 110 vm_page_t m); 111 static void vfs_clean_pages_dirty_buf(struct buf *bp); 112 static void vfs_setdirty_locked_object(struct buf *bp); 113 static void vfs_vmio_release(struct buf *bp); 114 static int vfs_bio_clcheck(struct vnode *vp, int size, 115 daddr_t lblkno, daddr_t blkno); 116 static int buf_flush(int); 117 static int flushbufqueues(int, int); 118 static void buf_daemon(void); 119 static void bremfreel(struct buf *bp); 120 static __inline void bd_wakeup(void); 121 static int sysctl_runningspace(SYSCTL_HANDLER_ARGS); 122 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 123 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 124 static int sysctl_bufspace(SYSCTL_HANDLER_ARGS); 125 #endif 126 127 int vmiodirenable = TRUE; 128 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, 129 "Use the VM system for directory writes"); 130 long runningbufspace; 131 SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 132 "Amount of presently outstanding async buffer io"); 133 static long bufspace; 134 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 135 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 136 SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD, 137 &bufspace, 0, sysctl_bufspace, "L", "Virtual memory used for buffers"); 138 #else 139 SYSCTL_LONG(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, 140 "Virtual memory used for buffers"); 141 #endif 142 static long unmapped_bufspace; 143 SYSCTL_LONG(_vfs, OID_AUTO, unmapped_bufspace, CTLFLAG_RD, 144 &unmapped_bufspace, 0, 145 "Amount of unmapped buffers, inclusive in the bufspace"); 146 static long maxbufspace; 147 SYSCTL_LONG(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0, 148 "Maximum allowed value of bufspace (including buf_daemon)"); 149 static long bufmallocspace; 150 SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 151 "Amount of malloced memory for buffers"); 152 static long maxbufmallocspace; 153 SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0, 154 "Maximum amount of malloced memory for buffers"); 155 static long lobufspace; 156 SYSCTL_LONG(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0, 157 "Minimum amount of buffers we want to have"); 158 long hibufspace; 159 SYSCTL_LONG(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0, 160 "Maximum allowed value of bufspace (excluding buf_daemon)"); 161 static int bufreusecnt; 162 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0, 163 "Number of times we have reused a buffer"); 164 static int buffreekvacnt; 165 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0, 166 "Number of times we have freed the KVA space from some buffer"); 167 static int bufdefragcnt; 168 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0, 169 "Number of times we have had to repeat buffer allocation to defragment"); 170 static long lorunningspace; 171 SYSCTL_PROC(_vfs, OID_AUTO, lorunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE | 172 CTLFLAG_RW, &lorunningspace, 0, sysctl_runningspace, "L", 173 "Minimum preferred space used for in-progress I/O"); 174 static long hirunningspace; 175 SYSCTL_PROC(_vfs, OID_AUTO, hirunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE | 176 CTLFLAG_RW, &hirunningspace, 0, sysctl_runningspace, "L", 177 "Maximum amount of space to use for in-progress I/O"); 178 int dirtybufferflushes; 179 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes, 180 0, "Number of bdwrite to bawrite conversions to limit dirty buffers"); 181 int bdwriteskip; 182 SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip, 183 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk"); 184 int altbufferflushes; 185 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes, 186 0, "Number of fsync flushes to limit dirty buffers"); 187 static int recursiveflushes; 188 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes, 189 0, "Number of flushes skipped due to being recursive"); 190 static int numdirtybuffers; 191 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0, 192 "Number of buffers that are dirty (has unwritten changes) at the moment"); 193 static int lodirtybuffers; 194 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0, 195 "How many buffers we want to have free before bufdaemon can sleep"); 196 static int hidirtybuffers; 197 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0, 198 "When the number of dirty buffers is considered severe"); 199 int dirtybufthresh; 200 SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh, 201 0, "Number of bdwrite to bawrite conversions to clear dirty buffers"); 202 static int numfreebuffers; 203 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, 204 "Number of free buffers"); 205 static int lofreebuffers; 206 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0, 207 "XXX Unused"); 208 static int hifreebuffers; 209 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0, 210 "XXX Complicatedly unused"); 211 static int getnewbufcalls; 212 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0, 213 "Number of calls to getnewbuf"); 214 static int getnewbufrestarts; 215 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0, 216 "Number of times getnewbuf has had to restart a buffer aquisition"); 217 static int mappingrestarts; 218 SYSCTL_INT(_vfs, OID_AUTO, mappingrestarts, CTLFLAG_RW, &mappingrestarts, 0, 219 "Number of times getblk has had to restart a buffer mapping for " 220 "unmapped buffer"); 221 static int flushbufqtarget = 100; 222 SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0, 223 "Amount of work to do in flushbufqueues when helping bufdaemon"); 224 static long notbufdflushes; 225 SYSCTL_LONG(_vfs, OID_AUTO, notbufdflushes, CTLFLAG_RD, ¬bufdflushes, 0, 226 "Number of dirty buffer flushes done by the bufdaemon helpers"); 227 static long barrierwrites; 228 SYSCTL_LONG(_vfs, OID_AUTO, barrierwrites, CTLFLAG_RW, &barrierwrites, 0, 229 "Number of barrier writes"); 230 SYSCTL_INT(_vfs, OID_AUTO, unmapped_buf_allowed, CTLFLAG_RD, 231 &unmapped_buf_allowed, 0, 232 "Permit the use of the unmapped i/o"); 233 234 /* 235 * Lock for the non-dirty bufqueues 236 */ 237 static struct mtx_padalign bqclean; 238 239 /* 240 * Lock for the dirty queue. 241 */ 242 static struct mtx_padalign bqdirty; 243 244 /* 245 * This lock synchronizes access to bd_request. 246 */ 247 static struct mtx_padalign bdlock; 248 249 /* 250 * This lock protects the runningbufreq and synchronizes runningbufwakeup and 251 * waitrunningbufspace(). 252 */ 253 static struct mtx_padalign rbreqlock; 254 255 /* 256 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it. 257 */ 258 static struct rwlock_padalign nblock; 259 260 /* 261 * Lock that protects bdirtywait. 262 */ 263 static struct mtx_padalign bdirtylock; 264 265 /* 266 * Wakeup point for bufdaemon, as well as indicator of whether it is already 267 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it 268 * is idling. 269 */ 270 static int bd_request; 271 272 /* 273 * Request for the buf daemon to write more buffers than is indicated by 274 * lodirtybuf. This may be necessary to push out excess dependencies or 275 * defragment the address space where a simple count of the number of dirty 276 * buffers is insufficient to characterize the demand for flushing them. 277 */ 278 static int bd_speedupreq; 279 280 /* 281 * bogus page -- for I/O to/from partially complete buffers 282 * this is a temporary solution to the problem, but it is not 283 * really that bad. it would be better to split the buffer 284 * for input in the case of buffers partially already in memory, 285 * but the code is intricate enough already. 286 */ 287 vm_page_t bogus_page; 288 289 /* 290 * Synchronization (sleep/wakeup) variable for active buffer space requests. 291 * Set when wait starts, cleared prior to wakeup(). 292 * Used in runningbufwakeup() and waitrunningbufspace(). 293 */ 294 static int runningbufreq; 295 296 /* 297 * Synchronization (sleep/wakeup) variable for buffer requests. 298 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done 299 * by and/or. 300 * Used in numdirtywakeup(), bufspacewakeup(), bufcountadd(), bwillwrite(), 301 * getnewbuf(), and getblk(). 302 */ 303 static volatile int needsbuffer; 304 305 /* 306 * Synchronization for bwillwrite() waiters. 307 */ 308 static int bdirtywait; 309 310 /* 311 * Definitions for the buffer free lists. 312 */ 313 #define BUFFER_QUEUES 5 /* number of free buffer queues */ 314 315 #define QUEUE_NONE 0 /* on no queue */ 316 #define QUEUE_CLEAN 1 /* non-B_DELWRI buffers */ 317 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */ 318 #define QUEUE_EMPTYKVA 3 /* empty buffer headers w/KVA assignment */ 319 #define QUEUE_EMPTY 4 /* empty buffer headers */ 320 #define QUEUE_SENTINEL 1024 /* not an queue index, but mark for sentinel */ 321 322 /* Queues for free buffers with various properties */ 323 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } }; 324 #ifdef INVARIANTS 325 static int bq_len[BUFFER_QUEUES]; 326 #endif 327 328 /* 329 * Single global constant for BUF_WMESG, to avoid getting multiple references. 330 * buf_wmesg is referred from macros. 331 */ 332 const char *buf_wmesg = BUF_WMESG; 333 334 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 335 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ 336 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 337 338 static int 339 sysctl_runningspace(SYSCTL_HANDLER_ARGS) 340 { 341 long value; 342 int error; 343 344 value = *(long *)arg1; 345 error = sysctl_handle_long(oidp, &value, 0, req); 346 if (error != 0 || req->newptr == NULL) 347 return (error); 348 mtx_lock(&rbreqlock); 349 if (arg1 == &hirunningspace) { 350 if (value < lorunningspace) 351 error = EINVAL; 352 else 353 hirunningspace = value; 354 } else { 355 KASSERT(arg1 == &lorunningspace, 356 ("%s: unknown arg1", __func__)); 357 if (value > hirunningspace) 358 error = EINVAL; 359 else 360 lorunningspace = value; 361 } 362 mtx_unlock(&rbreqlock); 363 return (error); 364 } 365 366 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 367 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 368 static int 369 sysctl_bufspace(SYSCTL_HANDLER_ARGS) 370 { 371 long lvalue; 372 int ivalue; 373 374 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long)) 375 return (sysctl_handle_long(oidp, arg1, arg2, req)); 376 lvalue = *(long *)arg1; 377 if (lvalue > INT_MAX) 378 /* On overflow, still write out a long to trigger ENOMEM. */ 379 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 380 ivalue = lvalue; 381 return (sysctl_handle_int(oidp, &ivalue, 0, req)); 382 } 383 #endif 384 385 /* 386 * bqlock: 387 * 388 * Return the appropriate queue lock based on the index. 389 */ 390 static inline struct mtx * 391 bqlock(int qindex) 392 { 393 394 if (qindex == QUEUE_DIRTY) 395 return (struct mtx *)(&bqdirty); 396 return (struct mtx *)(&bqclean); 397 } 398 399 /* 400 * bdirtywakeup: 401 * 402 * Wakeup any bwillwrite() waiters. 403 */ 404 static void 405 bdirtywakeup(void) 406 { 407 mtx_lock(&bdirtylock); 408 if (bdirtywait) { 409 bdirtywait = 0; 410 wakeup(&bdirtywait); 411 } 412 mtx_unlock(&bdirtylock); 413 } 414 415 /* 416 * bdirtysub: 417 * 418 * Decrement the numdirtybuffers count by one and wakeup any 419 * threads blocked in bwillwrite(). 420 */ 421 static void 422 bdirtysub(void) 423 { 424 425 if (atomic_fetchadd_int(&numdirtybuffers, -1) == 426 (lodirtybuffers + hidirtybuffers) / 2) 427 bdirtywakeup(); 428 } 429 430 /* 431 * bdirtyadd: 432 * 433 * Increment the numdirtybuffers count by one and wakeup the buf 434 * daemon if needed. 435 */ 436 static void 437 bdirtyadd(void) 438 { 439 440 /* 441 * Only do the wakeup once as we cross the boundary. The 442 * buf daemon will keep running until the condition clears. 443 */ 444 if (atomic_fetchadd_int(&numdirtybuffers, 1) == 445 (lodirtybuffers + hidirtybuffers) / 2) 446 bd_wakeup(); 447 } 448 449 /* 450 * bufspacewakeup: 451 * 452 * Called when buffer space is potentially available for recovery. 453 * getnewbuf() will block on this flag when it is unable to free 454 * sufficient buffer space. Buffer space becomes recoverable when 455 * bp's get placed back in the queues. 456 */ 457 458 static __inline void 459 bufspacewakeup(void) 460 { 461 int need_wakeup, on; 462 463 /* 464 * If someone is waiting for BUF space, wake them up. Even 465 * though we haven't freed the kva space yet, the waiting 466 * process will be able to now. 467 */ 468 rw_rlock(&nblock); 469 for (;;) { 470 need_wakeup = 0; 471 on = needsbuffer; 472 if ((on & VFS_BIO_NEED_BUFSPACE) == 0) 473 break; 474 need_wakeup = 1; 475 if (atomic_cmpset_rel_int(&needsbuffer, on, 476 on & ~VFS_BIO_NEED_BUFSPACE)) 477 break; 478 } 479 if (need_wakeup) 480 wakeup(__DEVOLATILE(void *, &needsbuffer)); 481 rw_runlock(&nblock); 482 } 483 484 /* 485 * runningwakeup: 486 * 487 * Wake up processes that are waiting on asynchronous writes to fall 488 * below lorunningspace. 489 */ 490 static void 491 runningwakeup(void) 492 { 493 494 mtx_lock(&rbreqlock); 495 if (runningbufreq) { 496 runningbufreq = 0; 497 wakeup(&runningbufreq); 498 } 499 mtx_unlock(&rbreqlock); 500 } 501 502 /* 503 * runningbufwakeup: 504 * 505 * Decrement the outstanding write count according. 506 */ 507 void 508 runningbufwakeup(struct buf *bp) 509 { 510 long space, bspace; 511 512 bspace = bp->b_runningbufspace; 513 if (bspace == 0) 514 return; 515 space = atomic_fetchadd_long(&runningbufspace, -bspace); 516 KASSERT(space >= bspace, ("runningbufspace underflow %ld %ld", 517 space, bspace)); 518 bp->b_runningbufspace = 0; 519 /* 520 * Only acquire the lock and wakeup on the transition from exceeding 521 * the threshold to falling below it. 522 */ 523 if (space < lorunningspace) 524 return; 525 if (space - bspace > lorunningspace) 526 return; 527 runningwakeup(); 528 } 529 530 /* 531 * bufcountadd: 532 * 533 * Called when a buffer has been added to one of the free queues to 534 * account for the buffer and to wakeup anyone waiting for free buffers. 535 * This typically occurs when large amounts of metadata are being handled 536 * by the buffer cache ( else buffer space runs out first, usually ). 537 */ 538 static __inline void 539 bufcountadd(struct buf *bp) 540 { 541 int mask, need_wakeup, old, on; 542 543 KASSERT((bp->b_flags & B_INFREECNT) == 0, 544 ("buf %p already counted as free", bp)); 545 bp->b_flags |= B_INFREECNT; 546 old = atomic_fetchadd_int(&numfreebuffers, 1); 547 KASSERT(old >= 0 && old < nbuf, 548 ("numfreebuffers climbed to %d", old + 1)); 549 mask = VFS_BIO_NEED_ANY; 550 if (numfreebuffers >= hifreebuffers) 551 mask |= VFS_BIO_NEED_FREE; 552 rw_rlock(&nblock); 553 for (;;) { 554 need_wakeup = 0; 555 on = needsbuffer; 556 if (on == 0) 557 break; 558 need_wakeup = 1; 559 if (atomic_cmpset_rel_int(&needsbuffer, on, on & ~mask)) 560 break; 561 } 562 if (need_wakeup) 563 wakeup(__DEVOLATILE(void *, &needsbuffer)); 564 rw_runlock(&nblock); 565 } 566 567 /* 568 * bufcountsub: 569 * 570 * Decrement the numfreebuffers count as needed. 571 */ 572 static void 573 bufcountsub(struct buf *bp) 574 { 575 int old; 576 577 /* 578 * Fixup numfreebuffers count. If the buffer is invalid or not 579 * delayed-write, the buffer was free and we must decrement 580 * numfreebuffers. 581 */ 582 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { 583 KASSERT((bp->b_flags & B_INFREECNT) != 0, 584 ("buf %p not counted in numfreebuffers", bp)); 585 bp->b_flags &= ~B_INFREECNT; 586 old = atomic_fetchadd_int(&numfreebuffers, -1); 587 KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1)); 588 } 589 } 590 591 /* 592 * waitrunningbufspace() 593 * 594 * runningbufspace is a measure of the amount of I/O currently 595 * running. This routine is used in async-write situations to 596 * prevent creating huge backups of pending writes to a device. 597 * Only asynchronous writes are governed by this function. 598 * 599 * This does NOT turn an async write into a sync write. It waits 600 * for earlier writes to complete and generally returns before the 601 * caller's write has reached the device. 602 */ 603 void 604 waitrunningbufspace(void) 605 { 606 607 mtx_lock(&rbreqlock); 608 while (runningbufspace > hirunningspace) { 609 runningbufreq = 1; 610 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 611 } 612 mtx_unlock(&rbreqlock); 613 } 614 615 616 /* 617 * vfs_buf_test_cache: 618 * 619 * Called when a buffer is extended. This function clears the B_CACHE 620 * bit if the newly extended portion of the buffer does not contain 621 * valid data. 622 */ 623 static __inline 624 void 625 vfs_buf_test_cache(struct buf *bp, 626 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 627 vm_page_t m) 628 { 629 630 VM_OBJECT_ASSERT_LOCKED(m->object); 631 if (bp->b_flags & B_CACHE) { 632 int base = (foff + off) & PAGE_MASK; 633 if (vm_page_is_valid(m, base, size) == 0) 634 bp->b_flags &= ~B_CACHE; 635 } 636 } 637 638 /* Wake up the buffer daemon if necessary */ 639 static __inline void 640 bd_wakeup(void) 641 { 642 643 mtx_lock(&bdlock); 644 if (bd_request == 0) { 645 bd_request = 1; 646 wakeup(&bd_request); 647 } 648 mtx_unlock(&bdlock); 649 } 650 651 /* 652 * bd_speedup - speedup the buffer cache flushing code 653 */ 654 void 655 bd_speedup(void) 656 { 657 int needwake; 658 659 mtx_lock(&bdlock); 660 needwake = 0; 661 if (bd_speedupreq == 0 || bd_request == 0) 662 needwake = 1; 663 bd_speedupreq = 1; 664 bd_request = 1; 665 if (needwake) 666 wakeup(&bd_request); 667 mtx_unlock(&bdlock); 668 } 669 670 #ifdef __i386__ 671 #define TRANSIENT_DENOM 5 672 #else 673 #define TRANSIENT_DENOM 10 674 #endif 675 676 /* 677 * Calculating buffer cache scaling values and reserve space for buffer 678 * headers. This is called during low level kernel initialization and 679 * may be called more then once. We CANNOT write to the memory area 680 * being reserved at this time. 681 */ 682 caddr_t 683 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 684 { 685 int tuned_nbuf; 686 long maxbuf, maxbuf_sz, buf_sz, biotmap_sz; 687 688 /* 689 * physmem_est is in pages. Convert it to kilobytes (assumes 690 * PAGE_SIZE is >= 1K) 691 */ 692 physmem_est = physmem_est * (PAGE_SIZE / 1024); 693 694 /* 695 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 696 * For the first 64MB of ram nominally allocate sufficient buffers to 697 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 698 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing 699 * the buffer cache we limit the eventual kva reservation to 700 * maxbcache bytes. 701 * 702 * factor represents the 1/4 x ram conversion. 703 */ 704 if (nbuf == 0) { 705 int factor = 4 * BKVASIZE / 1024; 706 707 nbuf = 50; 708 if (physmem_est > 4096) 709 nbuf += min((physmem_est - 4096) / factor, 710 65536 / factor); 711 if (physmem_est > 65536) 712 nbuf += min((physmem_est - 65536) * 2 / (factor * 5), 713 32 * 1024 * 1024 / (factor * 5)); 714 715 if (maxbcache && nbuf > maxbcache / BKVASIZE) 716 nbuf = maxbcache / BKVASIZE; 717 tuned_nbuf = 1; 718 } else 719 tuned_nbuf = 0; 720 721 /* XXX Avoid unsigned long overflows later on with maxbufspace. */ 722 maxbuf = (LONG_MAX / 3) / BKVASIZE; 723 if (nbuf > maxbuf) { 724 if (!tuned_nbuf) 725 printf("Warning: nbufs lowered from %d to %ld\n", nbuf, 726 maxbuf); 727 nbuf = maxbuf; 728 } 729 730 /* 731 * Ideal allocation size for the transient bio submap is 10% 732 * of the maximal space buffer map. This roughly corresponds 733 * to the amount of the buffer mapped for typical UFS load. 734 * 735 * Clip the buffer map to reserve space for the transient 736 * BIOs, if its extent is bigger than 90% (80% on i386) of the 737 * maximum buffer map extent on the platform. 738 * 739 * The fall-back to the maxbuf in case of maxbcache unset, 740 * allows to not trim the buffer KVA for the architectures 741 * with ample KVA space. 742 */ 743 if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) { 744 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE; 745 buf_sz = (long)nbuf * BKVASIZE; 746 if (buf_sz < maxbuf_sz / TRANSIENT_DENOM * 747 (TRANSIENT_DENOM - 1)) { 748 /* 749 * There is more KVA than memory. Do not 750 * adjust buffer map size, and assign the rest 751 * of maxbuf to transient map. 752 */ 753 biotmap_sz = maxbuf_sz - buf_sz; 754 } else { 755 /* 756 * Buffer map spans all KVA we could afford on 757 * this platform. Give 10% (20% on i386) of 758 * the buffer map to the transient bio map. 759 */ 760 biotmap_sz = buf_sz / TRANSIENT_DENOM; 761 buf_sz -= biotmap_sz; 762 } 763 if (biotmap_sz / INT_MAX > MAXPHYS) 764 bio_transient_maxcnt = INT_MAX; 765 else 766 bio_transient_maxcnt = biotmap_sz / MAXPHYS; 767 /* 768 * Artifically limit to 1024 simultaneous in-flight I/Os 769 * using the transient mapping. 770 */ 771 if (bio_transient_maxcnt > 1024) 772 bio_transient_maxcnt = 1024; 773 if (tuned_nbuf) 774 nbuf = buf_sz / BKVASIZE; 775 } 776 777 /* 778 * swbufs are used as temporary holders for I/O, such as paging I/O. 779 * We have no less then 16 and no more then 256. 780 */ 781 nswbuf = max(min(nbuf/4, 256), 16); 782 #ifdef NSWBUF_MIN 783 if (nswbuf < NSWBUF_MIN) 784 nswbuf = NSWBUF_MIN; 785 #endif 786 787 /* 788 * Reserve space for the buffer cache buffers 789 */ 790 swbuf = (void *)v; 791 v = (caddr_t)(swbuf + nswbuf); 792 buf = (void *)v; 793 v = (caddr_t)(buf + nbuf); 794 795 return(v); 796 } 797 798 /* Initialize the buffer subsystem. Called before use of any buffers. */ 799 void 800 bufinit(void) 801 { 802 struct buf *bp; 803 int i; 804 805 mtx_init(&bqclean, "bufq clean lock", NULL, MTX_DEF); 806 mtx_init(&bqdirty, "bufq dirty lock", NULL, MTX_DEF); 807 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 808 rw_init(&nblock, "needsbuffer lock"); 809 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 810 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF); 811 812 /* next, make a null set of free lists */ 813 for (i = 0; i < BUFFER_QUEUES; i++) 814 TAILQ_INIT(&bufqueues[i]); 815 816 /* finally, initialize each buffer header and stick on empty q */ 817 for (i = 0; i < nbuf; i++) { 818 bp = &buf[i]; 819 bzero(bp, sizeof *bp); 820 bp->b_flags = B_INVAL | B_INFREECNT; 821 bp->b_rcred = NOCRED; 822 bp->b_wcred = NOCRED; 823 bp->b_qindex = QUEUE_EMPTY; 824 bp->b_xflags = 0; 825 LIST_INIT(&bp->b_dep); 826 BUF_LOCKINIT(bp); 827 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 828 #ifdef INVARIANTS 829 bq_len[QUEUE_EMPTY]++; 830 #endif 831 } 832 833 /* 834 * maxbufspace is the absolute maximum amount of buffer space we are 835 * allowed to reserve in KVM and in real terms. The absolute maximum 836 * is nominally used by buf_daemon. hibufspace is the nominal maximum 837 * used by most other processes. The differential is required to 838 * ensure that buf_daemon is able to run when other processes might 839 * be blocked waiting for buffer space. 840 * 841 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 842 * this may result in KVM fragmentation which is not handled optimally 843 * by the system. 844 */ 845 maxbufspace = (long)nbuf * BKVASIZE; 846 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 847 lobufspace = hibufspace - MAXBSIZE; 848 849 /* 850 * Note: The 16 MiB upper limit for hirunningspace was chosen 851 * arbitrarily and may need further tuning. It corresponds to 852 * 128 outstanding write IO requests (if IO size is 128 KiB), 853 * which fits with many RAID controllers' tagged queuing limits. 854 * The lower 1 MiB limit is the historical upper limit for 855 * hirunningspace. 856 */ 857 hirunningspace = lmax(lmin(roundup(hibufspace / 64, MAXBSIZE), 858 16 * 1024 * 1024), 1024 * 1024); 859 lorunningspace = roundup((hirunningspace * 2) / 3, MAXBSIZE); 860 861 /* 862 * Limit the amount of malloc memory since it is wired permanently into 863 * the kernel space. Even though this is accounted for in the buffer 864 * allocation, we don't want the malloced region to grow uncontrolled. 865 * The malloc scheme improves memory utilization significantly on average 866 * (small) directories. 867 */ 868 maxbufmallocspace = hibufspace / 20; 869 870 /* 871 * Reduce the chance of a deadlock occuring by limiting the number 872 * of delayed-write dirty buffers we allow to stack up. 873 */ 874 hidirtybuffers = nbuf / 4 + 20; 875 dirtybufthresh = hidirtybuffers * 9 / 10; 876 numdirtybuffers = 0; 877 /* 878 * To support extreme low-memory systems, make sure hidirtybuffers cannot 879 * eat up all available buffer space. This occurs when our minimum cannot 880 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 881 * BKVASIZE'd buffers. 882 */ 883 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 884 hidirtybuffers >>= 1; 885 } 886 lodirtybuffers = hidirtybuffers / 2; 887 888 /* 889 * Try to keep the number of free buffers in the specified range, 890 * and give special processes (e.g. like buf_daemon) access to an 891 * emergency reserve. 892 */ 893 lofreebuffers = nbuf / 18 + 5; 894 hifreebuffers = 2 * lofreebuffers; 895 numfreebuffers = nbuf; 896 897 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ | 898 VM_ALLOC_NORMAL | VM_ALLOC_WIRED); 899 unmapped_buf = (caddr_t)kva_alloc(MAXPHYS); 900 } 901 902 #ifdef INVARIANTS 903 static inline void 904 vfs_buf_check_mapped(struct buf *bp) 905 { 906 907 KASSERT((bp->b_flags & B_UNMAPPED) == 0, 908 ("mapped buf %p %x", bp, bp->b_flags)); 909 KASSERT(bp->b_kvabase != unmapped_buf, 910 ("mapped buf: b_kvabase was not updated %p", bp)); 911 KASSERT(bp->b_data != unmapped_buf, 912 ("mapped buf: b_data was not updated %p", bp)); 913 } 914 915 static inline void 916 vfs_buf_check_unmapped(struct buf *bp) 917 { 918 919 KASSERT((bp->b_flags & B_UNMAPPED) == B_UNMAPPED, 920 ("unmapped buf %p %x", bp, bp->b_flags)); 921 KASSERT(bp->b_kvabase == unmapped_buf, 922 ("unmapped buf: corrupted b_kvabase %p", bp)); 923 KASSERT(bp->b_data == unmapped_buf, 924 ("unmapped buf: corrupted b_data %p", bp)); 925 } 926 927 #define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp) 928 #define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp) 929 #else 930 #define BUF_CHECK_MAPPED(bp) do {} while (0) 931 #define BUF_CHECK_UNMAPPED(bp) do {} while (0) 932 #endif 933 934 static void 935 bpmap_qenter(struct buf *bp) 936 { 937 938 BUF_CHECK_MAPPED(bp); 939 940 /* 941 * bp->b_data is relative to bp->b_offset, but 942 * bp->b_offset may be offset into the first page. 943 */ 944 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data); 945 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages); 946 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 947 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 948 } 949 950 /* 951 * bfreekva() - free the kva allocation for a buffer. 952 * 953 * Since this call frees up buffer space, we call bufspacewakeup(). 954 */ 955 static void 956 bfreekva(struct buf *bp) 957 { 958 959 if (bp->b_kvasize == 0) 960 return; 961 962 atomic_add_int(&buffreekvacnt, 1); 963 atomic_subtract_long(&bufspace, bp->b_kvasize); 964 if ((bp->b_flags & B_UNMAPPED) == 0) { 965 BUF_CHECK_MAPPED(bp); 966 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, 967 bp->b_kvasize); 968 } else { 969 BUF_CHECK_UNMAPPED(bp); 970 if ((bp->b_flags & B_KVAALLOC) != 0) { 971 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvaalloc, 972 bp->b_kvasize); 973 } 974 atomic_subtract_long(&unmapped_bufspace, bp->b_kvasize); 975 bp->b_flags &= ~(B_UNMAPPED | B_KVAALLOC); 976 } 977 bp->b_kvasize = 0; 978 bufspacewakeup(); 979 } 980 981 /* 982 * binsfree: 983 * 984 * Insert the buffer into the appropriate free list. 985 */ 986 static void 987 binsfree(struct buf *bp, int qindex) 988 { 989 struct mtx *olock, *nlock; 990 991 BUF_ASSERT_XLOCKED(bp); 992 993 olock = bqlock(bp->b_qindex); 994 nlock = bqlock(qindex); 995 mtx_lock(olock); 996 /* Handle delayed bremfree() processing. */ 997 if (bp->b_flags & B_REMFREE) 998 bremfreel(bp); 999 1000 if (bp->b_qindex != QUEUE_NONE) 1001 panic("binsfree: free buffer onto another queue???"); 1002 1003 bp->b_qindex = qindex; 1004 if (olock != nlock) { 1005 mtx_unlock(olock); 1006 mtx_lock(nlock); 1007 } 1008 if (bp->b_flags & B_AGE) 1009 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1010 else 1011 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1012 #ifdef INVARIANTS 1013 bq_len[bp->b_qindex]++; 1014 #endif 1015 mtx_unlock(nlock); 1016 1017 /* 1018 * Something we can maybe free or reuse. 1019 */ 1020 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1021 bufspacewakeup(); 1022 1023 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI)) 1024 bufcountadd(bp); 1025 } 1026 1027 /* 1028 * bremfree: 1029 * 1030 * Mark the buffer for removal from the appropriate free list. 1031 * 1032 */ 1033 void 1034 bremfree(struct buf *bp) 1035 { 1036 1037 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1038 KASSERT((bp->b_flags & B_REMFREE) == 0, 1039 ("bremfree: buffer %p already marked for delayed removal.", bp)); 1040 KASSERT(bp->b_qindex != QUEUE_NONE, 1041 ("bremfree: buffer %p not on a queue.", bp)); 1042 BUF_ASSERT_XLOCKED(bp); 1043 1044 bp->b_flags |= B_REMFREE; 1045 bufcountsub(bp); 1046 } 1047 1048 /* 1049 * bremfreef: 1050 * 1051 * Force an immediate removal from a free list. Used only in nfs when 1052 * it abuses the b_freelist pointer. 1053 */ 1054 void 1055 bremfreef(struct buf *bp) 1056 { 1057 struct mtx *qlock; 1058 1059 qlock = bqlock(bp->b_qindex); 1060 mtx_lock(qlock); 1061 bremfreel(bp); 1062 mtx_unlock(qlock); 1063 } 1064 1065 /* 1066 * bremfreel: 1067 * 1068 * Removes a buffer from the free list, must be called with the 1069 * correct qlock held. 1070 */ 1071 static void 1072 bremfreel(struct buf *bp) 1073 { 1074 1075 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X", 1076 bp, bp->b_vp, bp->b_flags); 1077 KASSERT(bp->b_qindex != QUEUE_NONE, 1078 ("bremfreel: buffer %p not on a queue.", bp)); 1079 BUF_ASSERT_XLOCKED(bp); 1080 mtx_assert(bqlock(bp->b_qindex), MA_OWNED); 1081 1082 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 1083 #ifdef INVARIANTS 1084 KASSERT(bq_len[bp->b_qindex] >= 1, ("queue %d underflow", 1085 bp->b_qindex)); 1086 bq_len[bp->b_qindex]--; 1087 #endif 1088 bp->b_qindex = QUEUE_NONE; 1089 /* 1090 * If this was a delayed bremfree() we only need to remove the buffer 1091 * from the queue and return the stats are already done. 1092 */ 1093 if (bp->b_flags & B_REMFREE) { 1094 bp->b_flags &= ~B_REMFREE; 1095 return; 1096 } 1097 bufcountsub(bp); 1098 } 1099 1100 /* 1101 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 1102 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 1103 * the buffer is valid and we do not have to do anything. 1104 */ 1105 void 1106 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, 1107 int cnt, struct ucred * cred) 1108 { 1109 struct buf *rabp; 1110 int i; 1111 1112 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 1113 if (inmem(vp, *rablkno)) 1114 continue; 1115 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 1116 1117 if ((rabp->b_flags & B_CACHE) == 0) { 1118 if (!TD_IS_IDLETHREAD(curthread)) 1119 curthread->td_ru.ru_inblock++; 1120 rabp->b_flags |= B_ASYNC; 1121 rabp->b_flags &= ~B_INVAL; 1122 rabp->b_ioflags &= ~BIO_ERROR; 1123 rabp->b_iocmd = BIO_READ; 1124 if (rabp->b_rcred == NOCRED && cred != NOCRED) 1125 rabp->b_rcred = crhold(cred); 1126 vfs_busy_pages(rabp, 0); 1127 BUF_KERNPROC(rabp); 1128 rabp->b_iooffset = dbtob(rabp->b_blkno); 1129 bstrategy(rabp); 1130 } else { 1131 brelse(rabp); 1132 } 1133 } 1134 } 1135 1136 /* 1137 * Entry point for bread() and breadn() via #defines in sys/buf.h. 1138 * 1139 * Get a buffer with the specified data. Look in the cache first. We 1140 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 1141 * is set, the buffer is valid and we do not have to do anything, see 1142 * getblk(). Also starts asynchronous I/O on read-ahead blocks. 1143 */ 1144 int 1145 breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno, 1146 int *rabsize, int cnt, struct ucred *cred, int flags, struct buf **bpp) 1147 { 1148 struct buf *bp; 1149 int rv = 0, readwait = 0; 1150 1151 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 1152 /* 1153 * Can only return NULL if GB_LOCK_NOWAIT flag is specified. 1154 */ 1155 *bpp = bp = getblk(vp, blkno, size, 0, 0, flags); 1156 if (bp == NULL) 1157 return (EBUSY); 1158 1159 /* if not found in cache, do some I/O */ 1160 if ((bp->b_flags & B_CACHE) == 0) { 1161 if (!TD_IS_IDLETHREAD(curthread)) 1162 curthread->td_ru.ru_inblock++; 1163 bp->b_iocmd = BIO_READ; 1164 bp->b_flags &= ~B_INVAL; 1165 bp->b_ioflags &= ~BIO_ERROR; 1166 if (bp->b_rcred == NOCRED && cred != NOCRED) 1167 bp->b_rcred = crhold(cred); 1168 vfs_busy_pages(bp, 0); 1169 bp->b_iooffset = dbtob(bp->b_blkno); 1170 bstrategy(bp); 1171 ++readwait; 1172 } 1173 1174 breada(vp, rablkno, rabsize, cnt, cred); 1175 1176 if (readwait) { 1177 rv = bufwait(bp); 1178 } 1179 return (rv); 1180 } 1181 1182 /* 1183 * Write, release buffer on completion. (Done by iodone 1184 * if async). Do not bother writing anything if the buffer 1185 * is invalid. 1186 * 1187 * Note that we set B_CACHE here, indicating that buffer is 1188 * fully valid and thus cacheable. This is true even of NFS 1189 * now so we set it generally. This could be set either here 1190 * or in biodone() since the I/O is synchronous. We put it 1191 * here. 1192 */ 1193 int 1194 bufwrite(struct buf *bp) 1195 { 1196 int oldflags; 1197 struct vnode *vp; 1198 long space; 1199 int vp_md; 1200 1201 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1202 if (bp->b_flags & B_INVAL) { 1203 brelse(bp); 1204 return (0); 1205 } 1206 1207 if (bp->b_flags & B_BARRIER) 1208 barrierwrites++; 1209 1210 oldflags = bp->b_flags; 1211 1212 BUF_ASSERT_HELD(bp); 1213 1214 if (bp->b_pin_count > 0) 1215 bunpin_wait(bp); 1216 1217 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 1218 ("FFS background buffer should not get here %p", bp)); 1219 1220 vp = bp->b_vp; 1221 if (vp) 1222 vp_md = vp->v_vflag & VV_MD; 1223 else 1224 vp_md = 0; 1225 1226 /* 1227 * Mark the buffer clean. Increment the bufobj write count 1228 * before bundirty() call, to prevent other thread from seeing 1229 * empty dirty list and zero counter for writes in progress, 1230 * falsely indicating that the bufobj is clean. 1231 */ 1232 bufobj_wref(bp->b_bufobj); 1233 bundirty(bp); 1234 1235 bp->b_flags &= ~B_DONE; 1236 bp->b_ioflags &= ~BIO_ERROR; 1237 bp->b_flags |= B_CACHE; 1238 bp->b_iocmd = BIO_WRITE; 1239 1240 vfs_busy_pages(bp, 1); 1241 1242 /* 1243 * Normal bwrites pipeline writes 1244 */ 1245 bp->b_runningbufspace = bp->b_bufsize; 1246 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace); 1247 1248 if (!TD_IS_IDLETHREAD(curthread)) 1249 curthread->td_ru.ru_oublock++; 1250 if (oldflags & B_ASYNC) 1251 BUF_KERNPROC(bp); 1252 bp->b_iooffset = dbtob(bp->b_blkno); 1253 bstrategy(bp); 1254 1255 if ((oldflags & B_ASYNC) == 0) { 1256 int rtval = bufwait(bp); 1257 brelse(bp); 1258 return (rtval); 1259 } else if (space > hirunningspace) { 1260 /* 1261 * don't allow the async write to saturate the I/O 1262 * system. We will not deadlock here because 1263 * we are blocking waiting for I/O that is already in-progress 1264 * to complete. We do not block here if it is the update 1265 * or syncer daemon trying to clean up as that can lead 1266 * to deadlock. 1267 */ 1268 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 1269 waitrunningbufspace(); 1270 } 1271 1272 return (0); 1273 } 1274 1275 void 1276 bufbdflush(struct bufobj *bo, struct buf *bp) 1277 { 1278 struct buf *nbp; 1279 1280 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 1281 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 1282 altbufferflushes++; 1283 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 1284 BO_LOCK(bo); 1285 /* 1286 * Try to find a buffer to flush. 1287 */ 1288 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 1289 if ((nbp->b_vflags & BV_BKGRDINPROG) || 1290 BUF_LOCK(nbp, 1291 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 1292 continue; 1293 if (bp == nbp) 1294 panic("bdwrite: found ourselves"); 1295 BO_UNLOCK(bo); 1296 /* Don't countdeps with the bo lock held. */ 1297 if (buf_countdeps(nbp, 0)) { 1298 BO_LOCK(bo); 1299 BUF_UNLOCK(nbp); 1300 continue; 1301 } 1302 if (nbp->b_flags & B_CLUSTEROK) { 1303 vfs_bio_awrite(nbp); 1304 } else { 1305 bremfree(nbp); 1306 bawrite(nbp); 1307 } 1308 dirtybufferflushes++; 1309 break; 1310 } 1311 if (nbp == NULL) 1312 BO_UNLOCK(bo); 1313 } 1314 } 1315 1316 /* 1317 * Delayed write. (Buffer is marked dirty). Do not bother writing 1318 * anything if the buffer is marked invalid. 1319 * 1320 * Note that since the buffer must be completely valid, we can safely 1321 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 1322 * biodone() in order to prevent getblk from writing the buffer 1323 * out synchronously. 1324 */ 1325 void 1326 bdwrite(struct buf *bp) 1327 { 1328 struct thread *td = curthread; 1329 struct vnode *vp; 1330 struct bufobj *bo; 1331 1332 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1333 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1334 KASSERT((bp->b_flags & B_BARRIER) == 0, 1335 ("Barrier request in delayed write %p", bp)); 1336 BUF_ASSERT_HELD(bp); 1337 1338 if (bp->b_flags & B_INVAL) { 1339 brelse(bp); 1340 return; 1341 } 1342 1343 /* 1344 * If we have too many dirty buffers, don't create any more. 1345 * If we are wildly over our limit, then force a complete 1346 * cleanup. Otherwise, just keep the situation from getting 1347 * out of control. Note that we have to avoid a recursive 1348 * disaster and not try to clean up after our own cleanup! 1349 */ 1350 vp = bp->b_vp; 1351 bo = bp->b_bufobj; 1352 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 1353 td->td_pflags |= TDP_INBDFLUSH; 1354 BO_BDFLUSH(bo, bp); 1355 td->td_pflags &= ~TDP_INBDFLUSH; 1356 } else 1357 recursiveflushes++; 1358 1359 bdirty(bp); 1360 /* 1361 * Set B_CACHE, indicating that the buffer is fully valid. This is 1362 * true even of NFS now. 1363 */ 1364 bp->b_flags |= B_CACHE; 1365 1366 /* 1367 * This bmap keeps the system from needing to do the bmap later, 1368 * perhaps when the system is attempting to do a sync. Since it 1369 * is likely that the indirect block -- or whatever other datastructure 1370 * that the filesystem needs is still in memory now, it is a good 1371 * thing to do this. Note also, that if the pageout daemon is 1372 * requesting a sync -- there might not be enough memory to do 1373 * the bmap then... So, this is important to do. 1374 */ 1375 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 1376 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 1377 } 1378 1379 /* 1380 * Set the *dirty* buffer range based upon the VM system dirty 1381 * pages. 1382 * 1383 * Mark the buffer pages as clean. We need to do this here to 1384 * satisfy the vnode_pager and the pageout daemon, so that it 1385 * thinks that the pages have been "cleaned". Note that since 1386 * the pages are in a delayed write buffer -- the VFS layer 1387 * "will" see that the pages get written out on the next sync, 1388 * or perhaps the cluster will be completed. 1389 */ 1390 vfs_clean_pages_dirty_buf(bp); 1391 bqrelse(bp); 1392 1393 /* 1394 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 1395 * due to the softdep code. 1396 */ 1397 } 1398 1399 /* 1400 * bdirty: 1401 * 1402 * Turn buffer into delayed write request. We must clear BIO_READ and 1403 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 1404 * itself to properly update it in the dirty/clean lists. We mark it 1405 * B_DONE to ensure that any asynchronization of the buffer properly 1406 * clears B_DONE ( else a panic will occur later ). 1407 * 1408 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 1409 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 1410 * should only be called if the buffer is known-good. 1411 * 1412 * Since the buffer is not on a queue, we do not update the numfreebuffers 1413 * count. 1414 * 1415 * The buffer must be on QUEUE_NONE. 1416 */ 1417 void 1418 bdirty(struct buf *bp) 1419 { 1420 1421 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 1422 bp, bp->b_vp, bp->b_flags); 1423 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1424 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1425 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1426 BUF_ASSERT_HELD(bp); 1427 bp->b_flags &= ~(B_RELBUF); 1428 bp->b_iocmd = BIO_WRITE; 1429 1430 if ((bp->b_flags & B_DELWRI) == 0) { 1431 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 1432 reassignbuf(bp); 1433 bdirtyadd(); 1434 } 1435 } 1436 1437 /* 1438 * bundirty: 1439 * 1440 * Clear B_DELWRI for buffer. 1441 * 1442 * Since the buffer is not on a queue, we do not update the numfreebuffers 1443 * count. 1444 * 1445 * The buffer must be on QUEUE_NONE. 1446 */ 1447 1448 void 1449 bundirty(struct buf *bp) 1450 { 1451 1452 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1453 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1454 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1455 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1456 BUF_ASSERT_HELD(bp); 1457 1458 if (bp->b_flags & B_DELWRI) { 1459 bp->b_flags &= ~B_DELWRI; 1460 reassignbuf(bp); 1461 bdirtysub(); 1462 } 1463 /* 1464 * Since it is now being written, we can clear its deferred write flag. 1465 */ 1466 bp->b_flags &= ~B_DEFERRED; 1467 } 1468 1469 /* 1470 * bawrite: 1471 * 1472 * Asynchronous write. Start output on a buffer, but do not wait for 1473 * it to complete. The buffer is released when the output completes. 1474 * 1475 * bwrite() ( or the VOP routine anyway ) is responsible for handling 1476 * B_INVAL buffers. Not us. 1477 */ 1478 void 1479 bawrite(struct buf *bp) 1480 { 1481 1482 bp->b_flags |= B_ASYNC; 1483 (void) bwrite(bp); 1484 } 1485 1486 /* 1487 * babarrierwrite: 1488 * 1489 * Asynchronous barrier write. Start output on a buffer, but do not 1490 * wait for it to complete. Place a write barrier after this write so 1491 * that this buffer and all buffers written before it are committed to 1492 * the disk before any buffers written after this write are committed 1493 * to the disk. The buffer is released when the output completes. 1494 */ 1495 void 1496 babarrierwrite(struct buf *bp) 1497 { 1498 1499 bp->b_flags |= B_ASYNC | B_BARRIER; 1500 (void) bwrite(bp); 1501 } 1502 1503 /* 1504 * bbarrierwrite: 1505 * 1506 * Synchronous barrier write. Start output on a buffer and wait for 1507 * it to complete. Place a write barrier after this write so that 1508 * this buffer and all buffers written before it are committed to 1509 * the disk before any buffers written after this write are committed 1510 * to the disk. The buffer is released when the output completes. 1511 */ 1512 int 1513 bbarrierwrite(struct buf *bp) 1514 { 1515 1516 bp->b_flags |= B_BARRIER; 1517 return (bwrite(bp)); 1518 } 1519 1520 /* 1521 * bwillwrite: 1522 * 1523 * Called prior to the locking of any vnodes when we are expecting to 1524 * write. We do not want to starve the buffer cache with too many 1525 * dirty buffers so we block here. By blocking prior to the locking 1526 * of any vnodes we attempt to avoid the situation where a locked vnode 1527 * prevents the various system daemons from flushing related buffers. 1528 */ 1529 void 1530 bwillwrite(void) 1531 { 1532 1533 if (numdirtybuffers >= hidirtybuffers) { 1534 mtx_lock(&bdirtylock); 1535 while (numdirtybuffers >= hidirtybuffers) { 1536 bdirtywait = 1; 1537 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4), 1538 "flswai", 0); 1539 } 1540 mtx_unlock(&bdirtylock); 1541 } 1542 } 1543 1544 /* 1545 * Return true if we have too many dirty buffers. 1546 */ 1547 int 1548 buf_dirty_count_severe(void) 1549 { 1550 1551 return(numdirtybuffers >= hidirtybuffers); 1552 } 1553 1554 static __noinline int 1555 buf_vm_page_count_severe(void) 1556 { 1557 1558 KFAIL_POINT_CODE(DEBUG_FP, buf_pressure, return 1); 1559 1560 return vm_page_count_severe(); 1561 } 1562 1563 /* 1564 * brelse: 1565 * 1566 * Release a busy buffer and, if requested, free its resources. The 1567 * buffer will be stashed in the appropriate bufqueue[] allowing it 1568 * to be accessed later as a cache entity or reused for other purposes. 1569 */ 1570 void 1571 brelse(struct buf *bp) 1572 { 1573 int qindex; 1574 1575 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 1576 bp, bp->b_vp, bp->b_flags); 1577 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1578 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1579 1580 if (BUF_LOCKRECURSED(bp)) { 1581 /* 1582 * Do not process, in particular, do not handle the 1583 * B_INVAL/B_RELBUF and do not release to free list. 1584 */ 1585 BUF_UNLOCK(bp); 1586 return; 1587 } 1588 1589 if (bp->b_flags & B_MANAGED) { 1590 bqrelse(bp); 1591 return; 1592 } 1593 1594 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 1595 bp->b_error == EIO && !(bp->b_flags & B_INVAL)) { 1596 /* 1597 * Failed write, redirty. Must clear BIO_ERROR to prevent 1598 * pages from being scrapped. If the error is anything 1599 * other than an I/O error (EIO), assume that retrying 1600 * is futile. 1601 */ 1602 bp->b_ioflags &= ~BIO_ERROR; 1603 bdirty(bp); 1604 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 1605 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 1606 /* 1607 * Either a failed I/O or we were asked to free or not 1608 * cache the buffer. 1609 */ 1610 bp->b_flags |= B_INVAL; 1611 if (!LIST_EMPTY(&bp->b_dep)) 1612 buf_deallocate(bp); 1613 if (bp->b_flags & B_DELWRI) 1614 bdirtysub(); 1615 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1616 if ((bp->b_flags & B_VMIO) == 0) { 1617 if (bp->b_bufsize) 1618 allocbuf(bp, 0); 1619 if (bp->b_vp) 1620 brelvp(bp); 1621 } 1622 } 1623 1624 /* 1625 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1626 * is called with B_DELWRI set, the underlying pages may wind up 1627 * getting freed causing a previous write (bdwrite()) to get 'lost' 1628 * because pages associated with a B_DELWRI bp are marked clean. 1629 * 1630 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1631 * if B_DELWRI is set. 1632 * 1633 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1634 * on pages to return pages to the VM page queues. 1635 */ 1636 if (bp->b_flags & B_DELWRI) 1637 bp->b_flags &= ~B_RELBUF; 1638 else if (buf_vm_page_count_severe()) { 1639 /* 1640 * BKGRDINPROG can only be set with the buf and bufobj 1641 * locks both held. We tolerate a race to clear it here. 1642 */ 1643 if (!(bp->b_vflags & BV_BKGRDINPROG)) 1644 bp->b_flags |= B_RELBUF; 1645 } 1646 1647 /* 1648 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1649 * constituted, not even NFS buffers now. Two flags effect this. If 1650 * B_INVAL, the struct buf is invalidated but the VM object is kept 1651 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1652 * 1653 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 1654 * invalidated. BIO_ERROR cannot be set for a failed write unless the 1655 * buffer is also B_INVAL because it hits the re-dirtying code above. 1656 * 1657 * Normally we can do this whether a buffer is B_DELWRI or not. If 1658 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1659 * the commit state and we cannot afford to lose the buffer. If the 1660 * buffer has a background write in progress, we need to keep it 1661 * around to prevent it from being reconstituted and starting a second 1662 * background write. 1663 */ 1664 if ((bp->b_flags & B_VMIO) 1665 && !(bp->b_vp->v_mount != NULL && 1666 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 1667 !vn_isdisk(bp->b_vp, NULL) && 1668 (bp->b_flags & B_DELWRI)) 1669 ) { 1670 1671 int i, j, resid; 1672 vm_page_t m; 1673 off_t foff; 1674 vm_pindex_t poff; 1675 vm_object_t obj; 1676 1677 obj = bp->b_bufobj->bo_object; 1678 1679 /* 1680 * Get the base offset and length of the buffer. Note that 1681 * in the VMIO case if the buffer block size is not 1682 * page-aligned then b_data pointer may not be page-aligned. 1683 * But our b_pages[] array *IS* page aligned. 1684 * 1685 * block sizes less then DEV_BSIZE (usually 512) are not 1686 * supported due to the page granularity bits (m->valid, 1687 * m->dirty, etc...). 1688 * 1689 * See man buf(9) for more information 1690 */ 1691 resid = bp->b_bufsize; 1692 foff = bp->b_offset; 1693 for (i = 0; i < bp->b_npages; i++) { 1694 int had_bogus = 0; 1695 1696 m = bp->b_pages[i]; 1697 1698 /* 1699 * If we hit a bogus page, fixup *all* the bogus pages 1700 * now. 1701 */ 1702 if (m == bogus_page) { 1703 poff = OFF_TO_IDX(bp->b_offset); 1704 had_bogus = 1; 1705 1706 VM_OBJECT_RLOCK(obj); 1707 for (j = i; j < bp->b_npages; j++) { 1708 vm_page_t mtmp; 1709 mtmp = bp->b_pages[j]; 1710 if (mtmp == bogus_page) { 1711 mtmp = vm_page_lookup(obj, poff + j); 1712 if (!mtmp) { 1713 panic("brelse: page missing\n"); 1714 } 1715 bp->b_pages[j] = mtmp; 1716 } 1717 } 1718 VM_OBJECT_RUNLOCK(obj); 1719 1720 if ((bp->b_flags & (B_INVAL | B_UNMAPPED)) == 0) { 1721 BUF_CHECK_MAPPED(bp); 1722 pmap_qenter( 1723 trunc_page((vm_offset_t)bp->b_data), 1724 bp->b_pages, bp->b_npages); 1725 } 1726 m = bp->b_pages[i]; 1727 } 1728 if ((bp->b_flags & B_NOCACHE) || 1729 (bp->b_ioflags & BIO_ERROR && 1730 bp->b_iocmd == BIO_READ)) { 1731 int poffset = foff & PAGE_MASK; 1732 int presid = resid > (PAGE_SIZE - poffset) ? 1733 (PAGE_SIZE - poffset) : resid; 1734 1735 KASSERT(presid >= 0, ("brelse: extra page")); 1736 VM_OBJECT_WLOCK(obj); 1737 while (vm_page_xbusied(m)) { 1738 vm_page_lock(m); 1739 VM_OBJECT_WUNLOCK(obj); 1740 vm_page_busy_sleep(m, "mbncsh"); 1741 VM_OBJECT_WLOCK(obj); 1742 } 1743 if (pmap_page_wired_mappings(m) == 0) 1744 vm_page_set_invalid(m, poffset, presid); 1745 VM_OBJECT_WUNLOCK(obj); 1746 if (had_bogus) 1747 printf("avoided corruption bug in bogus_page/brelse code\n"); 1748 } 1749 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1750 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1751 } 1752 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1753 vfs_vmio_release(bp); 1754 1755 } else if (bp->b_flags & B_VMIO) { 1756 1757 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1758 vfs_vmio_release(bp); 1759 } 1760 1761 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) { 1762 if (bp->b_bufsize != 0) 1763 allocbuf(bp, 0); 1764 if (bp->b_vp != NULL) 1765 brelvp(bp); 1766 } 1767 1768 /* 1769 * If the buffer has junk contents signal it and eventually 1770 * clean up B_DELWRI and diassociate the vnode so that gbincore() 1771 * doesn't find it. 1772 */ 1773 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 1774 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 1775 bp->b_flags |= B_INVAL; 1776 if (bp->b_flags & B_INVAL) { 1777 if (bp->b_flags & B_DELWRI) 1778 bundirty(bp); 1779 if (bp->b_vp) 1780 brelvp(bp); 1781 } 1782 1783 /* buffers with no memory */ 1784 if (bp->b_bufsize == 0) { 1785 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1786 if (bp->b_vflags & BV_BKGRDINPROG) 1787 panic("losing buffer 1"); 1788 if (bp->b_kvasize) 1789 qindex = QUEUE_EMPTYKVA; 1790 else 1791 qindex = QUEUE_EMPTY; 1792 bp->b_flags |= B_AGE; 1793 /* buffers with junk contents */ 1794 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 1795 (bp->b_ioflags & BIO_ERROR)) { 1796 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1797 if (bp->b_vflags & BV_BKGRDINPROG) 1798 panic("losing buffer 2"); 1799 qindex = QUEUE_CLEAN; 1800 bp->b_flags |= B_AGE; 1801 /* remaining buffers */ 1802 } else if (bp->b_flags & B_DELWRI) 1803 qindex = QUEUE_DIRTY; 1804 else 1805 qindex = QUEUE_CLEAN; 1806 1807 binsfree(bp, qindex); 1808 1809 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 1810 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1811 panic("brelse: not dirty"); 1812 /* unlock */ 1813 BUF_UNLOCK(bp); 1814 } 1815 1816 /* 1817 * Release a buffer back to the appropriate queue but do not try to free 1818 * it. The buffer is expected to be used again soon. 1819 * 1820 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1821 * biodone() to requeue an async I/O on completion. It is also used when 1822 * known good buffers need to be requeued but we think we may need the data 1823 * again soon. 1824 * 1825 * XXX we should be able to leave the B_RELBUF hint set on completion. 1826 */ 1827 void 1828 bqrelse(struct buf *bp) 1829 { 1830 int qindex; 1831 1832 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1833 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1834 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1835 1836 if (BUF_LOCKRECURSED(bp)) { 1837 /* do not release to free list */ 1838 BUF_UNLOCK(bp); 1839 return; 1840 } 1841 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1842 1843 if (bp->b_flags & B_MANAGED) { 1844 if (bp->b_flags & B_REMFREE) 1845 bremfreef(bp); 1846 goto out; 1847 } 1848 1849 /* buffers with stale but valid contents */ 1850 if (bp->b_flags & B_DELWRI) { 1851 qindex = QUEUE_DIRTY; 1852 } else { 1853 if ((bp->b_flags & B_DELWRI) == 0 && 1854 (bp->b_xflags & BX_VNDIRTY)) 1855 panic("bqrelse: not dirty"); 1856 /* 1857 * BKGRDINPROG can only be set with the buf and bufobj 1858 * locks both held. We tolerate a race to clear it here. 1859 */ 1860 if (buf_vm_page_count_severe() && 1861 (bp->b_vflags & BV_BKGRDINPROG) == 0) { 1862 /* 1863 * We are too low on memory, we have to try to free 1864 * the buffer (most importantly: the wired pages 1865 * making up its backing store) *now*. 1866 */ 1867 brelse(bp); 1868 return; 1869 } 1870 qindex = QUEUE_CLEAN; 1871 } 1872 binsfree(bp, qindex); 1873 1874 out: 1875 /* unlock */ 1876 BUF_UNLOCK(bp); 1877 } 1878 1879 /* Give pages used by the bp back to the VM system (where possible) */ 1880 static void 1881 vfs_vmio_release(struct buf *bp) 1882 { 1883 int i; 1884 vm_page_t m; 1885 1886 if ((bp->b_flags & B_UNMAPPED) == 0) { 1887 BUF_CHECK_MAPPED(bp); 1888 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages); 1889 } else 1890 BUF_CHECK_UNMAPPED(bp); 1891 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 1892 for (i = 0; i < bp->b_npages; i++) { 1893 m = bp->b_pages[i]; 1894 bp->b_pages[i] = NULL; 1895 /* 1896 * In order to keep page LRU ordering consistent, put 1897 * everything on the inactive queue. 1898 */ 1899 vm_page_lock(m); 1900 vm_page_unwire(m, PQ_INACTIVE); 1901 1902 /* 1903 * Might as well free the page if we can and it has 1904 * no valid data. We also free the page if the 1905 * buffer was used for direct I/O 1906 */ 1907 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid) { 1908 if (m->wire_count == 0 && !vm_page_busied(m)) 1909 vm_page_free(m); 1910 } else if (bp->b_flags & B_DIRECT) 1911 vm_page_try_to_free(m); 1912 else if (buf_vm_page_count_severe()) 1913 vm_page_try_to_cache(m); 1914 vm_page_unlock(m); 1915 } 1916 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 1917 1918 if (bp->b_bufsize) { 1919 bufspacewakeup(); 1920 bp->b_bufsize = 0; 1921 } 1922 bp->b_npages = 0; 1923 bp->b_flags &= ~B_VMIO; 1924 if (bp->b_vp) 1925 brelvp(bp); 1926 } 1927 1928 /* 1929 * Check to see if a block at a particular lbn is available for a clustered 1930 * write. 1931 */ 1932 static int 1933 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 1934 { 1935 struct buf *bpa; 1936 int match; 1937 1938 match = 0; 1939 1940 /* If the buf isn't in core skip it */ 1941 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 1942 return (0); 1943 1944 /* If the buf is busy we don't want to wait for it */ 1945 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1946 return (0); 1947 1948 /* Only cluster with valid clusterable delayed write buffers */ 1949 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 1950 (B_DELWRI | B_CLUSTEROK)) 1951 goto done; 1952 1953 if (bpa->b_bufsize != size) 1954 goto done; 1955 1956 /* 1957 * Check to see if it is in the expected place on disk and that the 1958 * block has been mapped. 1959 */ 1960 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 1961 match = 1; 1962 done: 1963 BUF_UNLOCK(bpa); 1964 return (match); 1965 } 1966 1967 /* 1968 * vfs_bio_awrite: 1969 * 1970 * Implement clustered async writes for clearing out B_DELWRI buffers. 1971 * This is much better then the old way of writing only one buffer at 1972 * a time. Note that we may not be presented with the buffers in the 1973 * correct order, so we search for the cluster in both directions. 1974 */ 1975 int 1976 vfs_bio_awrite(struct buf *bp) 1977 { 1978 struct bufobj *bo; 1979 int i; 1980 int j; 1981 daddr_t lblkno = bp->b_lblkno; 1982 struct vnode *vp = bp->b_vp; 1983 int ncl; 1984 int nwritten; 1985 int size; 1986 int maxcl; 1987 int gbflags; 1988 1989 bo = &vp->v_bufobj; 1990 gbflags = (bp->b_flags & B_UNMAPPED) != 0 ? GB_UNMAPPED : 0; 1991 /* 1992 * right now we support clustered writing only to regular files. If 1993 * we find a clusterable block we could be in the middle of a cluster 1994 * rather then at the beginning. 1995 */ 1996 if ((vp->v_type == VREG) && 1997 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1998 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1999 2000 size = vp->v_mount->mnt_stat.f_iosize; 2001 maxcl = MAXPHYS / size; 2002 2003 BO_RLOCK(bo); 2004 for (i = 1; i < maxcl; i++) 2005 if (vfs_bio_clcheck(vp, size, lblkno + i, 2006 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 2007 break; 2008 2009 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 2010 if (vfs_bio_clcheck(vp, size, lblkno - j, 2011 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 2012 break; 2013 BO_RUNLOCK(bo); 2014 --j; 2015 ncl = i + j; 2016 /* 2017 * this is a possible cluster write 2018 */ 2019 if (ncl != 1) { 2020 BUF_UNLOCK(bp); 2021 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl, 2022 gbflags); 2023 return (nwritten); 2024 } 2025 } 2026 bremfree(bp); 2027 bp->b_flags |= B_ASYNC; 2028 /* 2029 * default (old) behavior, writing out only one block 2030 * 2031 * XXX returns b_bufsize instead of b_bcount for nwritten? 2032 */ 2033 nwritten = bp->b_bufsize; 2034 (void) bwrite(bp); 2035 2036 return (nwritten); 2037 } 2038 2039 static void 2040 setbufkva(struct buf *bp, vm_offset_t addr, int maxsize, int gbflags) 2041 { 2042 2043 KASSERT((bp->b_flags & (B_UNMAPPED | B_KVAALLOC)) == 0 && 2044 bp->b_kvasize == 0, ("call bfreekva(%p)", bp)); 2045 if ((gbflags & GB_UNMAPPED) == 0) { 2046 bp->b_kvabase = (caddr_t)addr; 2047 } else if ((gbflags & GB_KVAALLOC) != 0) { 2048 KASSERT((gbflags & GB_UNMAPPED) != 0, 2049 ("GB_KVAALLOC without GB_UNMAPPED")); 2050 bp->b_kvaalloc = (caddr_t)addr; 2051 bp->b_flags |= B_UNMAPPED | B_KVAALLOC; 2052 atomic_add_long(&unmapped_bufspace, bp->b_kvasize); 2053 } 2054 bp->b_kvasize = maxsize; 2055 } 2056 2057 /* 2058 * Allocate the buffer KVA and set b_kvasize. Also set b_kvabase if 2059 * needed. 2060 */ 2061 static int 2062 allocbufkva(struct buf *bp, int maxsize, int gbflags) 2063 { 2064 vm_offset_t addr; 2065 2066 bfreekva(bp); 2067 addr = 0; 2068 2069 if (vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr)) { 2070 /* 2071 * Buffer map is too fragmented. Request the caller 2072 * to defragment the map. 2073 */ 2074 atomic_add_int(&bufdefragcnt, 1); 2075 return (1); 2076 } 2077 setbufkva(bp, addr, maxsize, gbflags); 2078 atomic_add_long(&bufspace, bp->b_kvasize); 2079 return (0); 2080 } 2081 2082 /* 2083 * Ask the bufdaemon for help, or act as bufdaemon itself, when a 2084 * locked vnode is supplied. 2085 */ 2086 static void 2087 getnewbuf_bufd_help(struct vnode *vp, int gbflags, int slpflag, int slptimeo, 2088 int defrag) 2089 { 2090 struct thread *td; 2091 char *waitmsg; 2092 int cnt, error, flags, norunbuf, wait; 2093 2094 mtx_assert(&bqclean, MA_OWNED); 2095 2096 if (defrag) { 2097 flags = VFS_BIO_NEED_BUFSPACE; 2098 waitmsg = "nbufkv"; 2099 } else if (bufspace >= hibufspace) { 2100 waitmsg = "nbufbs"; 2101 flags = VFS_BIO_NEED_BUFSPACE; 2102 } else { 2103 waitmsg = "newbuf"; 2104 flags = VFS_BIO_NEED_ANY; 2105 } 2106 atomic_set_int(&needsbuffer, flags); 2107 mtx_unlock(&bqclean); 2108 2109 bd_speedup(); /* heeeelp */ 2110 if ((gbflags & GB_NOWAIT_BD) != 0) 2111 return; 2112 2113 td = curthread; 2114 cnt = 0; 2115 wait = MNT_NOWAIT; 2116 rw_wlock(&nblock); 2117 while ((needsbuffer & flags) != 0) { 2118 if (vp != NULL && vp->v_type != VCHR && 2119 (td->td_pflags & TDP_BUFNEED) == 0) { 2120 rw_wunlock(&nblock); 2121 /* 2122 * getblk() is called with a vnode locked, and 2123 * some majority of the dirty buffers may as 2124 * well belong to the vnode. Flushing the 2125 * buffers there would make a progress that 2126 * cannot be achieved by the buf_daemon, that 2127 * cannot lock the vnode. 2128 */ 2129 if (cnt++ > 2) 2130 wait = MNT_WAIT; 2131 ASSERT_VOP_LOCKED(vp, "bufd_helper"); 2132 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 : 2133 vn_lock(vp, LK_TRYUPGRADE); 2134 if (error == 0) { 2135 /* play bufdaemon */ 2136 norunbuf = curthread_pflags_set(TDP_BUFNEED | 2137 TDP_NORUNNINGBUF); 2138 VOP_FSYNC(vp, wait, td); 2139 atomic_add_long(¬bufdflushes, 1); 2140 curthread_pflags_restore(norunbuf); 2141 } 2142 rw_wlock(&nblock); 2143 if ((needsbuffer & flags) == 0) 2144 break; 2145 } 2146 error = rw_sleep(__DEVOLATILE(void *, &needsbuffer), &nblock, 2147 (PRIBIO + 4) | slpflag, waitmsg, slptimeo); 2148 if (error != 0) 2149 break; 2150 } 2151 rw_wunlock(&nblock); 2152 } 2153 2154 static void 2155 getnewbuf_reuse_bp(struct buf *bp, int qindex) 2156 { 2157 2158 CTR6(KTR_BUF, "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d " 2159 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags, 2160 bp->b_kvasize, bp->b_bufsize, qindex); 2161 mtx_assert(&bqclean, MA_NOTOWNED); 2162 2163 /* 2164 * Note: we no longer distinguish between VMIO and non-VMIO 2165 * buffers. 2166 */ 2167 KASSERT((bp->b_flags & B_DELWRI) == 0, 2168 ("delwri buffer %p found in queue %d", bp, qindex)); 2169 2170 if (qindex == QUEUE_CLEAN) { 2171 if (bp->b_flags & B_VMIO) { 2172 bp->b_flags &= ~B_ASYNC; 2173 vfs_vmio_release(bp); 2174 } 2175 if (bp->b_vp != NULL) 2176 brelvp(bp); 2177 } 2178 2179 /* 2180 * Get the rest of the buffer freed up. b_kva* is still valid 2181 * after this operation. 2182 */ 2183 2184 if (bp->b_rcred != NOCRED) { 2185 crfree(bp->b_rcred); 2186 bp->b_rcred = NOCRED; 2187 } 2188 if (bp->b_wcred != NOCRED) { 2189 crfree(bp->b_wcred); 2190 bp->b_wcred = NOCRED; 2191 } 2192 if (!LIST_EMPTY(&bp->b_dep)) 2193 buf_deallocate(bp); 2194 if (bp->b_vflags & BV_BKGRDINPROG) 2195 panic("losing buffer 3"); 2196 KASSERT(bp->b_vp == NULL, ("bp: %p still has vnode %p. qindex: %d", 2197 bp, bp->b_vp, qindex)); 2198 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 2199 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags)); 2200 2201 if (bp->b_bufsize) 2202 allocbuf(bp, 0); 2203 2204 bp->b_flags &= B_UNMAPPED | B_KVAALLOC; 2205 bp->b_ioflags = 0; 2206 bp->b_xflags = 0; 2207 KASSERT((bp->b_flags & B_INFREECNT) == 0, 2208 ("buf %p still counted as free?", bp)); 2209 bp->b_vflags = 0; 2210 bp->b_vp = NULL; 2211 bp->b_blkno = bp->b_lblkno = 0; 2212 bp->b_offset = NOOFFSET; 2213 bp->b_iodone = 0; 2214 bp->b_error = 0; 2215 bp->b_resid = 0; 2216 bp->b_bcount = 0; 2217 bp->b_npages = 0; 2218 bp->b_dirtyoff = bp->b_dirtyend = 0; 2219 bp->b_bufobj = NULL; 2220 bp->b_pin_count = 0; 2221 bp->b_fsprivate1 = NULL; 2222 bp->b_fsprivate2 = NULL; 2223 bp->b_fsprivate3 = NULL; 2224 2225 LIST_INIT(&bp->b_dep); 2226 } 2227 2228 static int flushingbufs; 2229 2230 static struct buf * 2231 getnewbuf_scan(int maxsize, int defrag, int unmapped, int metadata) 2232 { 2233 struct buf *bp, *nbp; 2234 int nqindex, qindex, pass; 2235 2236 KASSERT(!unmapped || !defrag, ("both unmapped and defrag")); 2237 2238 pass = 1; 2239 restart: 2240 atomic_add_int(&getnewbufrestarts, 1); 2241 2242 /* 2243 * Setup for scan. If we do not have enough free buffers, 2244 * we setup a degenerate case that immediately fails. Note 2245 * that if we are specially marked process, we are allowed to 2246 * dip into our reserves. 2247 * 2248 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 2249 * for the allocation of the mapped buffer. For unmapped, the 2250 * easiest is to start with EMPTY outright. 2251 * 2252 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 2253 * However, there are a number of cases (defragging, reusing, ...) 2254 * where we cannot backup. 2255 */ 2256 nbp = NULL; 2257 mtx_lock(&bqclean); 2258 if (!defrag && unmapped) { 2259 nqindex = QUEUE_EMPTY; 2260 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 2261 } 2262 if (nbp == NULL) { 2263 nqindex = QUEUE_EMPTYKVA; 2264 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 2265 } 2266 2267 /* 2268 * If no EMPTYKVA buffers and we are either defragging or 2269 * reusing, locate a CLEAN buffer to free or reuse. If 2270 * bufspace useage is low skip this step so we can allocate a 2271 * new buffer. 2272 */ 2273 if (nbp == NULL && (defrag || bufspace >= lobufspace)) { 2274 nqindex = QUEUE_CLEAN; 2275 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2276 } 2277 2278 /* 2279 * If we could not find or were not allowed to reuse a CLEAN 2280 * buffer, check to see if it is ok to use an EMPTY buffer. 2281 * We can only use an EMPTY buffer if allocating its KVA would 2282 * not otherwise run us out of buffer space. No KVA is needed 2283 * for the unmapped allocation. 2284 */ 2285 if (nbp == NULL && defrag == 0 && (bufspace + maxsize < hibufspace || 2286 metadata)) { 2287 nqindex = QUEUE_EMPTY; 2288 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 2289 } 2290 2291 /* 2292 * All available buffers might be clean, retry ignoring the 2293 * lobufspace as the last resort. 2294 */ 2295 if (nbp == NULL && !TAILQ_EMPTY(&bufqueues[QUEUE_CLEAN])) { 2296 nqindex = QUEUE_CLEAN; 2297 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2298 } 2299 2300 /* 2301 * Run scan, possibly freeing data and/or kva mappings on the fly 2302 * depending. 2303 */ 2304 while ((bp = nbp) != NULL) { 2305 qindex = nqindex; 2306 2307 /* 2308 * Calculate next bp (we can only use it if we do not 2309 * block or do other fancy things). 2310 */ 2311 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 2312 switch (qindex) { 2313 case QUEUE_EMPTY: 2314 nqindex = QUEUE_EMPTYKVA; 2315 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 2316 if (nbp != NULL) 2317 break; 2318 /* FALLTHROUGH */ 2319 case QUEUE_EMPTYKVA: 2320 nqindex = QUEUE_CLEAN; 2321 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2322 if (nbp != NULL) 2323 break; 2324 /* FALLTHROUGH */ 2325 case QUEUE_CLEAN: 2326 if (metadata && pass == 1) { 2327 pass = 2; 2328 nqindex = QUEUE_EMPTY; 2329 nbp = TAILQ_FIRST( 2330 &bufqueues[QUEUE_EMPTY]); 2331 } 2332 /* 2333 * nbp is NULL. 2334 */ 2335 break; 2336 } 2337 } 2338 /* 2339 * If we are defragging then we need a buffer with 2340 * b_kvasize != 0. XXX this situation should no longer 2341 * occur, if defrag is non-zero the buffer's b_kvasize 2342 * should also be non-zero at this point. XXX 2343 */ 2344 if (defrag && bp->b_kvasize == 0) { 2345 printf("Warning: defrag empty buffer %p\n", bp); 2346 continue; 2347 } 2348 2349 /* 2350 * Start freeing the bp. This is somewhat involved. nbp 2351 * remains valid only for QUEUE_EMPTY[KVA] bp's. 2352 */ 2353 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2354 continue; 2355 /* 2356 * BKGRDINPROG can only be set with the buf and bufobj 2357 * locks both held. We tolerate a race to clear it here. 2358 */ 2359 if (bp->b_vflags & BV_BKGRDINPROG) { 2360 BUF_UNLOCK(bp); 2361 continue; 2362 } 2363 2364 KASSERT(bp->b_qindex == qindex, 2365 ("getnewbuf: inconsistent queue %d bp %p", qindex, bp)); 2366 2367 bremfreel(bp); 2368 mtx_unlock(&bqclean); 2369 /* 2370 * NOTE: nbp is now entirely invalid. We can only restart 2371 * the scan from this point on. 2372 */ 2373 2374 getnewbuf_reuse_bp(bp, qindex); 2375 mtx_assert(&bqclean, MA_NOTOWNED); 2376 2377 /* 2378 * If we are defragging then free the buffer. 2379 */ 2380 if (defrag) { 2381 bp->b_flags |= B_INVAL; 2382 bfreekva(bp); 2383 brelse(bp); 2384 defrag = 0; 2385 goto restart; 2386 } 2387 2388 /* 2389 * Notify any waiters for the buffer lock about 2390 * identity change by freeing the buffer. 2391 */ 2392 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp)) { 2393 bp->b_flags |= B_INVAL; 2394 bfreekva(bp); 2395 brelse(bp); 2396 goto restart; 2397 } 2398 2399 if (metadata) 2400 break; 2401 2402 /* 2403 * If we are overcomitted then recover the buffer and its 2404 * KVM space. This occurs in rare situations when multiple 2405 * processes are blocked in getnewbuf() or allocbuf(). 2406 */ 2407 if (bufspace >= hibufspace) 2408 flushingbufs = 1; 2409 if (flushingbufs && bp->b_kvasize != 0) { 2410 bp->b_flags |= B_INVAL; 2411 bfreekva(bp); 2412 brelse(bp); 2413 goto restart; 2414 } 2415 if (bufspace < lobufspace) 2416 flushingbufs = 0; 2417 break; 2418 } 2419 return (bp); 2420 } 2421 2422 /* 2423 * getnewbuf: 2424 * 2425 * Find and initialize a new buffer header, freeing up existing buffers 2426 * in the bufqueues as necessary. The new buffer is returned locked. 2427 * 2428 * Important: B_INVAL is not set. If the caller wishes to throw the 2429 * buffer away, the caller must set B_INVAL prior to calling brelse(). 2430 * 2431 * We block if: 2432 * We have insufficient buffer headers 2433 * We have insufficient buffer space 2434 * buffer_arena is too fragmented ( space reservation fails ) 2435 * If we have to flush dirty buffers ( but we try to avoid this ) 2436 */ 2437 static struct buf * 2438 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int size, int maxsize, 2439 int gbflags) 2440 { 2441 struct buf *bp; 2442 int defrag, metadata; 2443 2444 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 2445 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 2446 if (!unmapped_buf_allowed) 2447 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC); 2448 2449 defrag = 0; 2450 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 || 2451 vp->v_type == VCHR) 2452 metadata = 1; 2453 else 2454 metadata = 0; 2455 /* 2456 * We can't afford to block since we might be holding a vnode lock, 2457 * which may prevent system daemons from running. We deal with 2458 * low-memory situations by proactively returning memory and running 2459 * async I/O rather then sync I/O. 2460 */ 2461 atomic_add_int(&getnewbufcalls, 1); 2462 atomic_subtract_int(&getnewbufrestarts, 1); 2463 restart: 2464 bp = getnewbuf_scan(maxsize, defrag, (gbflags & (GB_UNMAPPED | 2465 GB_KVAALLOC)) == GB_UNMAPPED, metadata); 2466 if (bp != NULL) 2467 defrag = 0; 2468 2469 /* 2470 * If we exhausted our list, sleep as appropriate. We may have to 2471 * wakeup various daemons and write out some dirty buffers. 2472 * 2473 * Generally we are sleeping due to insufficient buffer space. 2474 */ 2475 if (bp == NULL) { 2476 mtx_assert(&bqclean, MA_OWNED); 2477 getnewbuf_bufd_help(vp, gbflags, slpflag, slptimeo, defrag); 2478 mtx_assert(&bqclean, MA_NOTOWNED); 2479 } else if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == GB_UNMAPPED) { 2480 mtx_assert(&bqclean, MA_NOTOWNED); 2481 2482 bfreekva(bp); 2483 bp->b_flags |= B_UNMAPPED; 2484 bp->b_kvabase = bp->b_data = unmapped_buf; 2485 bp->b_kvasize = maxsize; 2486 atomic_add_long(&bufspace, bp->b_kvasize); 2487 atomic_add_long(&unmapped_bufspace, bp->b_kvasize); 2488 atomic_add_int(&bufreusecnt, 1); 2489 } else { 2490 mtx_assert(&bqclean, MA_NOTOWNED); 2491 2492 /* 2493 * We finally have a valid bp. We aren't quite out of the 2494 * woods, we still have to reserve kva space. In order 2495 * to keep fragmentation sane we only allocate kva in 2496 * BKVASIZE chunks. 2497 */ 2498 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2499 2500 if (maxsize != bp->b_kvasize || (bp->b_flags & (B_UNMAPPED | 2501 B_KVAALLOC)) == B_UNMAPPED) { 2502 if (allocbufkva(bp, maxsize, gbflags)) { 2503 defrag = 1; 2504 bp->b_flags |= B_INVAL; 2505 brelse(bp); 2506 goto restart; 2507 } 2508 atomic_add_int(&bufreusecnt, 1); 2509 } else if ((bp->b_flags & B_KVAALLOC) != 0 && 2510 (gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == 0) { 2511 /* 2512 * If the reused buffer has KVA allocated, 2513 * reassign b_kvaalloc to b_kvabase. 2514 */ 2515 bp->b_kvabase = bp->b_kvaalloc; 2516 bp->b_flags &= ~B_KVAALLOC; 2517 atomic_subtract_long(&unmapped_bufspace, 2518 bp->b_kvasize); 2519 atomic_add_int(&bufreusecnt, 1); 2520 } else if ((bp->b_flags & (B_UNMAPPED | B_KVAALLOC)) == 0 && 2521 (gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == (GB_UNMAPPED | 2522 GB_KVAALLOC)) { 2523 /* 2524 * The case of reused buffer already have KVA 2525 * mapped, but the request is for unmapped 2526 * buffer with KVA allocated. 2527 */ 2528 bp->b_kvaalloc = bp->b_kvabase; 2529 bp->b_data = bp->b_kvabase = unmapped_buf; 2530 bp->b_flags |= B_UNMAPPED | B_KVAALLOC; 2531 atomic_add_long(&unmapped_bufspace, 2532 bp->b_kvasize); 2533 atomic_add_int(&bufreusecnt, 1); 2534 } 2535 if ((gbflags & GB_UNMAPPED) == 0) { 2536 bp->b_saveaddr = bp->b_kvabase; 2537 bp->b_data = bp->b_saveaddr; 2538 bp->b_flags &= ~B_UNMAPPED; 2539 BUF_CHECK_MAPPED(bp); 2540 } 2541 } 2542 return (bp); 2543 } 2544 2545 /* 2546 * buf_daemon: 2547 * 2548 * buffer flushing daemon. Buffers are normally flushed by the 2549 * update daemon but if it cannot keep up this process starts to 2550 * take the load in an attempt to prevent getnewbuf() from blocking. 2551 */ 2552 2553 static struct kproc_desc buf_kp = { 2554 "bufdaemon", 2555 buf_daemon, 2556 &bufdaemonproc 2557 }; 2558 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 2559 2560 static int 2561 buf_flush(int target) 2562 { 2563 int flushed; 2564 2565 flushed = flushbufqueues(target, 0); 2566 if (flushed == 0) { 2567 /* 2568 * Could not find any buffers without rollback 2569 * dependencies, so just write the first one 2570 * in the hopes of eventually making progress. 2571 */ 2572 flushed = flushbufqueues(target, 1); 2573 } 2574 return (flushed); 2575 } 2576 2577 static void 2578 buf_daemon() 2579 { 2580 int lodirty; 2581 2582 /* 2583 * This process needs to be suspended prior to shutdown sync. 2584 */ 2585 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2586 SHUTDOWN_PRI_LAST); 2587 2588 /* 2589 * This process is allowed to take the buffer cache to the limit 2590 */ 2591 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 2592 mtx_lock(&bdlock); 2593 for (;;) { 2594 bd_request = 0; 2595 mtx_unlock(&bdlock); 2596 2597 kproc_suspend_check(bufdaemonproc); 2598 lodirty = lodirtybuffers; 2599 if (bd_speedupreq) { 2600 lodirty = numdirtybuffers / 2; 2601 bd_speedupreq = 0; 2602 } 2603 /* 2604 * Do the flush. Limit the amount of in-transit I/O we 2605 * allow to build up, otherwise we would completely saturate 2606 * the I/O system. 2607 */ 2608 while (numdirtybuffers > lodirty) { 2609 if (buf_flush(numdirtybuffers - lodirty) == 0) 2610 break; 2611 kern_yield(PRI_USER); 2612 } 2613 2614 /* 2615 * Only clear bd_request if we have reached our low water 2616 * mark. The buf_daemon normally waits 1 second and 2617 * then incrementally flushes any dirty buffers that have 2618 * built up, within reason. 2619 * 2620 * If we were unable to hit our low water mark and couldn't 2621 * find any flushable buffers, we sleep for a short period 2622 * to avoid endless loops on unlockable buffers. 2623 */ 2624 mtx_lock(&bdlock); 2625 if (numdirtybuffers <= lodirtybuffers) { 2626 /* 2627 * We reached our low water mark, reset the 2628 * request and sleep until we are needed again. 2629 * The sleep is just so the suspend code works. 2630 */ 2631 bd_request = 0; 2632 /* 2633 * Do an extra wakeup in case dirty threshold 2634 * changed via sysctl and the explicit transition 2635 * out of shortfall was missed. 2636 */ 2637 bdirtywakeup(); 2638 if (runningbufspace <= lorunningspace) 2639 runningwakeup(); 2640 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 2641 } else { 2642 /* 2643 * We couldn't find any flushable dirty buffers but 2644 * still have too many dirty buffers, we 2645 * have to sleep and try again. (rare) 2646 */ 2647 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 2648 } 2649 } 2650 } 2651 2652 /* 2653 * flushbufqueues: 2654 * 2655 * Try to flush a buffer in the dirty queue. We must be careful to 2656 * free up B_INVAL buffers instead of write them, which NFS is 2657 * particularly sensitive to. 2658 */ 2659 static int flushwithdeps = 0; 2660 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 2661 0, "Number of buffers flushed with dependecies that require rollbacks"); 2662 2663 static int 2664 flushbufqueues(int target, int flushdeps) 2665 { 2666 struct buf *sentinel; 2667 struct vnode *vp; 2668 struct mount *mp; 2669 struct buf *bp; 2670 int hasdeps; 2671 int flushed; 2672 int queue; 2673 int error; 2674 2675 flushed = 0; 2676 queue = QUEUE_DIRTY; 2677 bp = NULL; 2678 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 2679 sentinel->b_qindex = QUEUE_SENTINEL; 2680 mtx_lock(&bqdirty); 2681 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist); 2682 mtx_unlock(&bqdirty); 2683 while (flushed != target) { 2684 maybe_yield(); 2685 mtx_lock(&bqdirty); 2686 bp = TAILQ_NEXT(sentinel, b_freelist); 2687 if (bp != NULL) { 2688 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2689 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel, 2690 b_freelist); 2691 } else { 2692 mtx_unlock(&bqdirty); 2693 break; 2694 } 2695 KASSERT(bp->b_qindex != QUEUE_SENTINEL, 2696 ("parallel calls to flushbufqueues() bp %p", bp)); 2697 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL); 2698 mtx_unlock(&bqdirty); 2699 if (error != 0) 2700 continue; 2701 if (bp->b_pin_count > 0) { 2702 BUF_UNLOCK(bp); 2703 continue; 2704 } 2705 /* 2706 * BKGRDINPROG can only be set with the buf and bufobj 2707 * locks both held. We tolerate a race to clear it here. 2708 */ 2709 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 2710 (bp->b_flags & B_DELWRI) == 0) { 2711 BUF_UNLOCK(bp); 2712 continue; 2713 } 2714 if (bp->b_flags & B_INVAL) { 2715 bremfreef(bp); 2716 brelse(bp); 2717 flushed++; 2718 continue; 2719 } 2720 2721 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 2722 if (flushdeps == 0) { 2723 BUF_UNLOCK(bp); 2724 continue; 2725 } 2726 hasdeps = 1; 2727 } else 2728 hasdeps = 0; 2729 /* 2730 * We must hold the lock on a vnode before writing 2731 * one of its buffers. Otherwise we may confuse, or 2732 * in the case of a snapshot vnode, deadlock the 2733 * system. 2734 * 2735 * The lock order here is the reverse of the normal 2736 * of vnode followed by buf lock. This is ok because 2737 * the NOWAIT will prevent deadlock. 2738 */ 2739 vp = bp->b_vp; 2740 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 2741 BUF_UNLOCK(bp); 2742 continue; 2743 } 2744 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT); 2745 if (error == 0) { 2746 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 2747 bp, bp->b_vp, bp->b_flags); 2748 vfs_bio_awrite(bp); 2749 vn_finished_write(mp); 2750 VOP_UNLOCK(vp, 0); 2751 flushwithdeps += hasdeps; 2752 flushed++; 2753 if (runningbufspace > hirunningspace) 2754 waitrunningbufspace(); 2755 continue; 2756 } 2757 vn_finished_write(mp); 2758 BUF_UNLOCK(bp); 2759 } 2760 mtx_lock(&bqdirty); 2761 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2762 mtx_unlock(&bqdirty); 2763 free(sentinel, M_TEMP); 2764 return (flushed); 2765 } 2766 2767 /* 2768 * Check to see if a block is currently memory resident. 2769 */ 2770 struct buf * 2771 incore(struct bufobj *bo, daddr_t blkno) 2772 { 2773 struct buf *bp; 2774 2775 BO_RLOCK(bo); 2776 bp = gbincore(bo, blkno); 2777 BO_RUNLOCK(bo); 2778 return (bp); 2779 } 2780 2781 /* 2782 * Returns true if no I/O is needed to access the 2783 * associated VM object. This is like incore except 2784 * it also hunts around in the VM system for the data. 2785 */ 2786 2787 static int 2788 inmem(struct vnode * vp, daddr_t blkno) 2789 { 2790 vm_object_t obj; 2791 vm_offset_t toff, tinc, size; 2792 vm_page_t m; 2793 vm_ooffset_t off; 2794 2795 ASSERT_VOP_LOCKED(vp, "inmem"); 2796 2797 if (incore(&vp->v_bufobj, blkno)) 2798 return 1; 2799 if (vp->v_mount == NULL) 2800 return 0; 2801 obj = vp->v_object; 2802 if (obj == NULL) 2803 return (0); 2804 2805 size = PAGE_SIZE; 2806 if (size > vp->v_mount->mnt_stat.f_iosize) 2807 size = vp->v_mount->mnt_stat.f_iosize; 2808 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2809 2810 VM_OBJECT_RLOCK(obj); 2811 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2812 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2813 if (!m) 2814 goto notinmem; 2815 tinc = size; 2816 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2817 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2818 if (vm_page_is_valid(m, 2819 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2820 goto notinmem; 2821 } 2822 VM_OBJECT_RUNLOCK(obj); 2823 return 1; 2824 2825 notinmem: 2826 VM_OBJECT_RUNLOCK(obj); 2827 return (0); 2828 } 2829 2830 /* 2831 * Set the dirty range for a buffer based on the status of the dirty 2832 * bits in the pages comprising the buffer. The range is limited 2833 * to the size of the buffer. 2834 * 2835 * Tell the VM system that the pages associated with this buffer 2836 * are clean. This is used for delayed writes where the data is 2837 * going to go to disk eventually without additional VM intevention. 2838 * 2839 * Note that while we only really need to clean through to b_bcount, we 2840 * just go ahead and clean through to b_bufsize. 2841 */ 2842 static void 2843 vfs_clean_pages_dirty_buf(struct buf *bp) 2844 { 2845 vm_ooffset_t foff, noff, eoff; 2846 vm_page_t m; 2847 int i; 2848 2849 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 2850 return; 2851 2852 foff = bp->b_offset; 2853 KASSERT(bp->b_offset != NOOFFSET, 2854 ("vfs_clean_pages_dirty_buf: no buffer offset")); 2855 2856 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 2857 vfs_drain_busy_pages(bp); 2858 vfs_setdirty_locked_object(bp); 2859 for (i = 0; i < bp->b_npages; i++) { 2860 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2861 eoff = noff; 2862 if (eoff > bp->b_offset + bp->b_bufsize) 2863 eoff = bp->b_offset + bp->b_bufsize; 2864 m = bp->b_pages[i]; 2865 vfs_page_set_validclean(bp, foff, m); 2866 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 2867 foff = noff; 2868 } 2869 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 2870 } 2871 2872 static void 2873 vfs_setdirty_locked_object(struct buf *bp) 2874 { 2875 vm_object_t object; 2876 int i; 2877 2878 object = bp->b_bufobj->bo_object; 2879 VM_OBJECT_ASSERT_WLOCKED(object); 2880 2881 /* 2882 * We qualify the scan for modified pages on whether the 2883 * object has been flushed yet. 2884 */ 2885 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) { 2886 vm_offset_t boffset; 2887 vm_offset_t eoffset; 2888 2889 /* 2890 * test the pages to see if they have been modified directly 2891 * by users through the VM system. 2892 */ 2893 for (i = 0; i < bp->b_npages; i++) 2894 vm_page_test_dirty(bp->b_pages[i]); 2895 2896 /* 2897 * Calculate the encompassing dirty range, boffset and eoffset, 2898 * (eoffset - boffset) bytes. 2899 */ 2900 2901 for (i = 0; i < bp->b_npages; i++) { 2902 if (bp->b_pages[i]->dirty) 2903 break; 2904 } 2905 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2906 2907 for (i = bp->b_npages - 1; i >= 0; --i) { 2908 if (bp->b_pages[i]->dirty) { 2909 break; 2910 } 2911 } 2912 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2913 2914 /* 2915 * Fit it to the buffer. 2916 */ 2917 2918 if (eoffset > bp->b_bcount) 2919 eoffset = bp->b_bcount; 2920 2921 /* 2922 * If we have a good dirty range, merge with the existing 2923 * dirty range. 2924 */ 2925 2926 if (boffset < eoffset) { 2927 if (bp->b_dirtyoff > boffset) 2928 bp->b_dirtyoff = boffset; 2929 if (bp->b_dirtyend < eoffset) 2930 bp->b_dirtyend = eoffset; 2931 } 2932 } 2933 } 2934 2935 /* 2936 * Allocate the KVA mapping for an existing buffer. It handles the 2937 * cases of both B_UNMAPPED buffer, and buffer with the preallocated 2938 * KVA which is not mapped (B_KVAALLOC). 2939 */ 2940 static void 2941 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags) 2942 { 2943 struct buf *scratch_bp; 2944 int bsize, maxsize, need_mapping, need_kva; 2945 off_t offset; 2946 2947 need_mapping = (bp->b_flags & B_UNMAPPED) != 0 && 2948 (gbflags & GB_UNMAPPED) == 0; 2949 need_kva = (bp->b_flags & (B_KVAALLOC | B_UNMAPPED)) == B_UNMAPPED && 2950 (gbflags & GB_KVAALLOC) != 0; 2951 if (!need_mapping && !need_kva) 2952 return; 2953 2954 BUF_CHECK_UNMAPPED(bp); 2955 2956 if (need_mapping && (bp->b_flags & B_KVAALLOC) != 0) { 2957 /* 2958 * Buffer is not mapped, but the KVA was already 2959 * reserved at the time of the instantiation. Use the 2960 * allocated space. 2961 */ 2962 bp->b_flags &= ~B_KVAALLOC; 2963 KASSERT(bp->b_kvaalloc != 0, ("kvaalloc == 0")); 2964 bp->b_kvabase = bp->b_kvaalloc; 2965 atomic_subtract_long(&unmapped_bufspace, bp->b_kvasize); 2966 goto has_addr; 2967 } 2968 2969 /* 2970 * Calculate the amount of the address space we would reserve 2971 * if the buffer was mapped. 2972 */ 2973 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize; 2974 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 2975 offset = blkno * bsize; 2976 maxsize = size + (offset & PAGE_MASK); 2977 maxsize = imax(maxsize, bsize); 2978 2979 mapping_loop: 2980 if (allocbufkva(bp, maxsize, gbflags)) { 2981 /* 2982 * Request defragmentation. getnewbuf() returns us the 2983 * allocated space by the scratch buffer KVA. 2984 */ 2985 scratch_bp = getnewbuf(bp->b_vp, 0, 0, size, maxsize, gbflags | 2986 (GB_UNMAPPED | GB_KVAALLOC)); 2987 if (scratch_bp == NULL) { 2988 if ((gbflags & GB_NOWAIT_BD) != 0) { 2989 /* 2990 * XXXKIB: defragmentation cannot 2991 * succeed, not sure what else to do. 2992 */ 2993 panic("GB_NOWAIT_BD and B_UNMAPPED %p", bp); 2994 } 2995 atomic_add_int(&mappingrestarts, 1); 2996 goto mapping_loop; 2997 } 2998 KASSERT((scratch_bp->b_flags & B_KVAALLOC) != 0, 2999 ("scratch bp !B_KVAALLOC %p", scratch_bp)); 3000 setbufkva(bp, (vm_offset_t)scratch_bp->b_kvaalloc, 3001 scratch_bp->b_kvasize, gbflags); 3002 3003 /* Get rid of the scratch buffer. */ 3004 scratch_bp->b_kvasize = 0; 3005 scratch_bp->b_flags |= B_INVAL; 3006 scratch_bp->b_flags &= ~(B_UNMAPPED | B_KVAALLOC); 3007 brelse(scratch_bp); 3008 } 3009 if (!need_mapping) 3010 return; 3011 3012 has_addr: 3013 bp->b_saveaddr = bp->b_kvabase; 3014 bp->b_data = bp->b_saveaddr; /* b_offset is handled by bpmap_qenter */ 3015 bp->b_flags &= ~B_UNMAPPED; 3016 BUF_CHECK_MAPPED(bp); 3017 bpmap_qenter(bp); 3018 } 3019 3020 /* 3021 * getblk: 3022 * 3023 * Get a block given a specified block and offset into a file/device. 3024 * The buffers B_DONE bit will be cleared on return, making it almost 3025 * ready for an I/O initiation. B_INVAL may or may not be set on 3026 * return. The caller should clear B_INVAL prior to initiating a 3027 * READ. 3028 * 3029 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 3030 * an existing buffer. 3031 * 3032 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 3033 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 3034 * and then cleared based on the backing VM. If the previous buffer is 3035 * non-0-sized but invalid, B_CACHE will be cleared. 3036 * 3037 * If getblk() must create a new buffer, the new buffer is returned with 3038 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 3039 * case it is returned with B_INVAL clear and B_CACHE set based on the 3040 * backing VM. 3041 * 3042 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 3043 * B_CACHE bit is clear. 3044 * 3045 * What this means, basically, is that the caller should use B_CACHE to 3046 * determine whether the buffer is fully valid or not and should clear 3047 * B_INVAL prior to issuing a read. If the caller intends to validate 3048 * the buffer by loading its data area with something, the caller needs 3049 * to clear B_INVAL. If the caller does this without issuing an I/O, 3050 * the caller should set B_CACHE ( as an optimization ), else the caller 3051 * should issue the I/O and biodone() will set B_CACHE if the I/O was 3052 * a write attempt or if it was a successfull read. If the caller 3053 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 3054 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 3055 */ 3056 struct buf * 3057 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3058 int flags) 3059 { 3060 struct buf *bp; 3061 struct bufobj *bo; 3062 int bsize, error, maxsize, vmio; 3063 off_t offset; 3064 3065 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 3066 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3067 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3068 ASSERT_VOP_LOCKED(vp, "getblk"); 3069 if (size > MAXBSIZE) 3070 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 3071 if (!unmapped_buf_allowed) 3072 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3073 3074 bo = &vp->v_bufobj; 3075 loop: 3076 BO_RLOCK(bo); 3077 bp = gbincore(bo, blkno); 3078 if (bp != NULL) { 3079 int lockflags; 3080 /* 3081 * Buffer is in-core. If the buffer is not busy nor managed, 3082 * it must be on a queue. 3083 */ 3084 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 3085 3086 if (flags & GB_LOCK_NOWAIT) 3087 lockflags |= LK_NOWAIT; 3088 3089 error = BUF_TIMELOCK(bp, lockflags, 3090 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo); 3091 3092 /* 3093 * If we slept and got the lock we have to restart in case 3094 * the buffer changed identities. 3095 */ 3096 if (error == ENOLCK) 3097 goto loop; 3098 /* We timed out or were interrupted. */ 3099 else if (error) 3100 return (NULL); 3101 /* If recursed, assume caller knows the rules. */ 3102 else if (BUF_LOCKRECURSED(bp)) 3103 goto end; 3104 3105 /* 3106 * The buffer is locked. B_CACHE is cleared if the buffer is 3107 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 3108 * and for a VMIO buffer B_CACHE is adjusted according to the 3109 * backing VM cache. 3110 */ 3111 if (bp->b_flags & B_INVAL) 3112 bp->b_flags &= ~B_CACHE; 3113 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 3114 bp->b_flags |= B_CACHE; 3115 if (bp->b_flags & B_MANAGED) 3116 MPASS(bp->b_qindex == QUEUE_NONE); 3117 else 3118 bremfree(bp); 3119 3120 /* 3121 * check for size inconsistencies for non-VMIO case. 3122 */ 3123 if (bp->b_bcount != size) { 3124 if ((bp->b_flags & B_VMIO) == 0 || 3125 (size > bp->b_kvasize)) { 3126 if (bp->b_flags & B_DELWRI) { 3127 /* 3128 * If buffer is pinned and caller does 3129 * not want sleep waiting for it to be 3130 * unpinned, bail out 3131 * */ 3132 if (bp->b_pin_count > 0) { 3133 if (flags & GB_LOCK_NOWAIT) { 3134 bqrelse(bp); 3135 return (NULL); 3136 } else { 3137 bunpin_wait(bp); 3138 } 3139 } 3140 bp->b_flags |= B_NOCACHE; 3141 bwrite(bp); 3142 } else { 3143 if (LIST_EMPTY(&bp->b_dep)) { 3144 bp->b_flags |= B_RELBUF; 3145 brelse(bp); 3146 } else { 3147 bp->b_flags |= B_NOCACHE; 3148 bwrite(bp); 3149 } 3150 } 3151 goto loop; 3152 } 3153 } 3154 3155 /* 3156 * Handle the case of unmapped buffer which should 3157 * become mapped, or the buffer for which KVA 3158 * reservation is requested. 3159 */ 3160 bp_unmapped_get_kva(bp, blkno, size, flags); 3161 3162 /* 3163 * If the size is inconsistant in the VMIO case, we can resize 3164 * the buffer. This might lead to B_CACHE getting set or 3165 * cleared. If the size has not changed, B_CACHE remains 3166 * unchanged from its previous state. 3167 */ 3168 if (bp->b_bcount != size) 3169 allocbuf(bp, size); 3170 3171 KASSERT(bp->b_offset != NOOFFSET, 3172 ("getblk: no buffer offset")); 3173 3174 /* 3175 * A buffer with B_DELWRI set and B_CACHE clear must 3176 * be committed before we can return the buffer in 3177 * order to prevent the caller from issuing a read 3178 * ( due to B_CACHE not being set ) and overwriting 3179 * it. 3180 * 3181 * Most callers, including NFS and FFS, need this to 3182 * operate properly either because they assume they 3183 * can issue a read if B_CACHE is not set, or because 3184 * ( for example ) an uncached B_DELWRI might loop due 3185 * to softupdates re-dirtying the buffer. In the latter 3186 * case, B_CACHE is set after the first write completes, 3187 * preventing further loops. 3188 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 3189 * above while extending the buffer, we cannot allow the 3190 * buffer to remain with B_CACHE set after the write 3191 * completes or it will represent a corrupt state. To 3192 * deal with this we set B_NOCACHE to scrap the buffer 3193 * after the write. 3194 * 3195 * We might be able to do something fancy, like setting 3196 * B_CACHE in bwrite() except if B_DELWRI is already set, 3197 * so the below call doesn't set B_CACHE, but that gets real 3198 * confusing. This is much easier. 3199 */ 3200 3201 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 3202 bp->b_flags |= B_NOCACHE; 3203 bwrite(bp); 3204 goto loop; 3205 } 3206 bp->b_flags &= ~B_DONE; 3207 } else { 3208 /* 3209 * Buffer is not in-core, create new buffer. The buffer 3210 * returned by getnewbuf() is locked. Note that the returned 3211 * buffer is also considered valid (not marked B_INVAL). 3212 */ 3213 BO_RUNLOCK(bo); 3214 /* 3215 * If the user does not want us to create the buffer, bail out 3216 * here. 3217 */ 3218 if (flags & GB_NOCREAT) 3219 return NULL; 3220 if (numfreebuffers == 0 && TD_IS_IDLETHREAD(curthread)) 3221 return NULL; 3222 3223 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize; 3224 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3225 offset = blkno * bsize; 3226 vmio = vp->v_object != NULL; 3227 if (vmio) { 3228 maxsize = size + (offset & PAGE_MASK); 3229 } else { 3230 maxsize = size; 3231 /* Do not allow non-VMIO notmapped buffers. */ 3232 flags &= ~GB_UNMAPPED; 3233 } 3234 maxsize = imax(maxsize, bsize); 3235 3236 bp = getnewbuf(vp, slpflag, slptimeo, size, maxsize, flags); 3237 if (bp == NULL) { 3238 if (slpflag || slptimeo) 3239 return NULL; 3240 goto loop; 3241 } 3242 3243 /* 3244 * This code is used to make sure that a buffer is not 3245 * created while the getnewbuf routine is blocked. 3246 * This can be a problem whether the vnode is locked or not. 3247 * If the buffer is created out from under us, we have to 3248 * throw away the one we just created. 3249 * 3250 * Note: this must occur before we associate the buffer 3251 * with the vp especially considering limitations in 3252 * the splay tree implementation when dealing with duplicate 3253 * lblkno's. 3254 */ 3255 BO_LOCK(bo); 3256 if (gbincore(bo, blkno)) { 3257 BO_UNLOCK(bo); 3258 bp->b_flags |= B_INVAL; 3259 brelse(bp); 3260 goto loop; 3261 } 3262 3263 /* 3264 * Insert the buffer into the hash, so that it can 3265 * be found by incore. 3266 */ 3267 bp->b_blkno = bp->b_lblkno = blkno; 3268 bp->b_offset = offset; 3269 bgetvp(vp, bp); 3270 BO_UNLOCK(bo); 3271 3272 /* 3273 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 3274 * buffer size starts out as 0, B_CACHE will be set by 3275 * allocbuf() for the VMIO case prior to it testing the 3276 * backing store for validity. 3277 */ 3278 3279 if (vmio) { 3280 bp->b_flags |= B_VMIO; 3281 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 3282 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 3283 bp, vp->v_object, bp->b_bufobj->bo_object)); 3284 } else { 3285 bp->b_flags &= ~B_VMIO; 3286 KASSERT(bp->b_bufobj->bo_object == NULL, 3287 ("ARGH! has b_bufobj->bo_object %p %p\n", 3288 bp, bp->b_bufobj->bo_object)); 3289 BUF_CHECK_MAPPED(bp); 3290 } 3291 3292 allocbuf(bp, size); 3293 bp->b_flags &= ~B_DONE; 3294 } 3295 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 3296 BUF_ASSERT_HELD(bp); 3297 end: 3298 KASSERT(bp->b_bufobj == bo, 3299 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 3300 return (bp); 3301 } 3302 3303 /* 3304 * Get an empty, disassociated buffer of given size. The buffer is initially 3305 * set to B_INVAL. 3306 */ 3307 struct buf * 3308 geteblk(int size, int flags) 3309 { 3310 struct buf *bp; 3311 int maxsize; 3312 3313 maxsize = (size + BKVAMASK) & ~BKVAMASK; 3314 while ((bp = getnewbuf(NULL, 0, 0, size, maxsize, flags)) == NULL) { 3315 if ((flags & GB_NOWAIT_BD) && 3316 (curthread->td_pflags & TDP_BUFNEED) != 0) 3317 return (NULL); 3318 } 3319 allocbuf(bp, size); 3320 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 3321 BUF_ASSERT_HELD(bp); 3322 return (bp); 3323 } 3324 3325 3326 /* 3327 * This code constitutes the buffer memory from either anonymous system 3328 * memory (in the case of non-VMIO operations) or from an associated 3329 * VM object (in the case of VMIO operations). This code is able to 3330 * resize a buffer up or down. 3331 * 3332 * Note that this code is tricky, and has many complications to resolve 3333 * deadlock or inconsistant data situations. Tread lightly!!! 3334 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 3335 * the caller. Calling this code willy nilly can result in the loss of data. 3336 * 3337 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 3338 * B_CACHE for the non-VMIO case. 3339 */ 3340 3341 int 3342 allocbuf(struct buf *bp, int size) 3343 { 3344 int newbsize, mbsize; 3345 int i; 3346 3347 BUF_ASSERT_HELD(bp); 3348 3349 if (bp->b_kvasize < size) 3350 panic("allocbuf: buffer too small"); 3351 3352 if ((bp->b_flags & B_VMIO) == 0) { 3353 caddr_t origbuf; 3354 int origbufsize; 3355 /* 3356 * Just get anonymous memory from the kernel. Don't 3357 * mess with B_CACHE. 3358 */ 3359 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3360 if (bp->b_flags & B_MALLOC) 3361 newbsize = mbsize; 3362 else 3363 newbsize = round_page(size); 3364 3365 if (newbsize < bp->b_bufsize) { 3366 /* 3367 * malloced buffers are not shrunk 3368 */ 3369 if (bp->b_flags & B_MALLOC) { 3370 if (newbsize) { 3371 bp->b_bcount = size; 3372 } else { 3373 free(bp->b_data, M_BIOBUF); 3374 if (bp->b_bufsize) { 3375 atomic_subtract_long( 3376 &bufmallocspace, 3377 bp->b_bufsize); 3378 bufspacewakeup(); 3379 bp->b_bufsize = 0; 3380 } 3381 bp->b_saveaddr = bp->b_kvabase; 3382 bp->b_data = bp->b_saveaddr; 3383 bp->b_bcount = 0; 3384 bp->b_flags &= ~B_MALLOC; 3385 } 3386 return 1; 3387 } 3388 vm_hold_free_pages(bp, newbsize); 3389 } else if (newbsize > bp->b_bufsize) { 3390 /* 3391 * We only use malloced memory on the first allocation. 3392 * and revert to page-allocated memory when the buffer 3393 * grows. 3394 */ 3395 /* 3396 * There is a potential smp race here that could lead 3397 * to bufmallocspace slightly passing the max. It 3398 * is probably extremely rare and not worth worrying 3399 * over. 3400 */ 3401 if ( (bufmallocspace < maxbufmallocspace) && 3402 (bp->b_bufsize == 0) && 3403 (mbsize <= PAGE_SIZE/2)) { 3404 3405 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 3406 bp->b_bufsize = mbsize; 3407 bp->b_bcount = size; 3408 bp->b_flags |= B_MALLOC; 3409 atomic_add_long(&bufmallocspace, mbsize); 3410 return 1; 3411 } 3412 origbuf = NULL; 3413 origbufsize = 0; 3414 /* 3415 * If the buffer is growing on its other-than-first allocation, 3416 * then we revert to the page-allocation scheme. 3417 */ 3418 if (bp->b_flags & B_MALLOC) { 3419 origbuf = bp->b_data; 3420 origbufsize = bp->b_bufsize; 3421 bp->b_data = bp->b_kvabase; 3422 if (bp->b_bufsize) { 3423 atomic_subtract_long(&bufmallocspace, 3424 bp->b_bufsize); 3425 bufspacewakeup(); 3426 bp->b_bufsize = 0; 3427 } 3428 bp->b_flags &= ~B_MALLOC; 3429 newbsize = round_page(newbsize); 3430 } 3431 vm_hold_load_pages( 3432 bp, 3433 (vm_offset_t) bp->b_data + bp->b_bufsize, 3434 (vm_offset_t) bp->b_data + newbsize); 3435 if (origbuf) { 3436 bcopy(origbuf, bp->b_data, origbufsize); 3437 free(origbuf, M_BIOBUF); 3438 } 3439 } 3440 } else { 3441 int desiredpages; 3442 3443 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3444 desiredpages = (size == 0) ? 0 : 3445 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 3446 3447 if (bp->b_flags & B_MALLOC) 3448 panic("allocbuf: VMIO buffer can't be malloced"); 3449 /* 3450 * Set B_CACHE initially if buffer is 0 length or will become 3451 * 0-length. 3452 */ 3453 if (size == 0 || bp->b_bufsize == 0) 3454 bp->b_flags |= B_CACHE; 3455 3456 if (newbsize < bp->b_bufsize) { 3457 /* 3458 * DEV_BSIZE aligned new buffer size is less then the 3459 * DEV_BSIZE aligned existing buffer size. Figure out 3460 * if we have to remove any pages. 3461 */ 3462 if (desiredpages < bp->b_npages) { 3463 vm_page_t m; 3464 3465 if ((bp->b_flags & B_UNMAPPED) == 0) { 3466 BUF_CHECK_MAPPED(bp); 3467 pmap_qremove((vm_offset_t)trunc_page( 3468 (vm_offset_t)bp->b_data) + 3469 (desiredpages << PAGE_SHIFT), 3470 (bp->b_npages - desiredpages)); 3471 } else 3472 BUF_CHECK_UNMAPPED(bp); 3473 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 3474 for (i = desiredpages; i < bp->b_npages; i++) { 3475 /* 3476 * the page is not freed here -- it 3477 * is the responsibility of 3478 * vnode_pager_setsize 3479 */ 3480 m = bp->b_pages[i]; 3481 KASSERT(m != bogus_page, 3482 ("allocbuf: bogus page found")); 3483 while (vm_page_sleep_if_busy(m, 3484 "biodep")) 3485 continue; 3486 3487 bp->b_pages[i] = NULL; 3488 vm_page_lock(m); 3489 vm_page_unwire(m, PQ_INACTIVE); 3490 vm_page_unlock(m); 3491 } 3492 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 3493 bp->b_npages = desiredpages; 3494 } 3495 } else if (size > bp->b_bcount) { 3496 /* 3497 * We are growing the buffer, possibly in a 3498 * byte-granular fashion. 3499 */ 3500 vm_object_t obj; 3501 vm_offset_t toff; 3502 vm_offset_t tinc; 3503 3504 /* 3505 * Step 1, bring in the VM pages from the object, 3506 * allocating them if necessary. We must clear 3507 * B_CACHE if these pages are not valid for the 3508 * range covered by the buffer. 3509 */ 3510 3511 obj = bp->b_bufobj->bo_object; 3512 3513 VM_OBJECT_WLOCK(obj); 3514 while (bp->b_npages < desiredpages) { 3515 vm_page_t m; 3516 3517 /* 3518 * We must allocate system pages since blocking 3519 * here could interfere with paging I/O, no 3520 * matter which process we are. 3521 * 3522 * Only exclusive busy can be tested here. 3523 * Blocking on shared busy might lead to 3524 * deadlocks once allocbuf() is called after 3525 * pages are vfs_busy_pages(). 3526 */ 3527 m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) + 3528 bp->b_npages, VM_ALLOC_NOBUSY | 3529 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED | 3530 VM_ALLOC_IGN_SBUSY | 3531 VM_ALLOC_COUNT(desiredpages - bp->b_npages)); 3532 if (m->valid == 0) 3533 bp->b_flags &= ~B_CACHE; 3534 bp->b_pages[bp->b_npages] = m; 3535 ++bp->b_npages; 3536 } 3537 3538 /* 3539 * Step 2. We've loaded the pages into the buffer, 3540 * we have to figure out if we can still have B_CACHE 3541 * set. Note that B_CACHE is set according to the 3542 * byte-granular range ( bcount and size ), new the 3543 * aligned range ( newbsize ). 3544 * 3545 * The VM test is against m->valid, which is DEV_BSIZE 3546 * aligned. Needless to say, the validity of the data 3547 * needs to also be DEV_BSIZE aligned. Note that this 3548 * fails with NFS if the server or some other client 3549 * extends the file's EOF. If our buffer is resized, 3550 * B_CACHE may remain set! XXX 3551 */ 3552 3553 toff = bp->b_bcount; 3554 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 3555 3556 while ((bp->b_flags & B_CACHE) && toff < size) { 3557 vm_pindex_t pi; 3558 3559 if (tinc > (size - toff)) 3560 tinc = size - toff; 3561 3562 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 3563 PAGE_SHIFT; 3564 3565 vfs_buf_test_cache( 3566 bp, 3567 bp->b_offset, 3568 toff, 3569 tinc, 3570 bp->b_pages[pi] 3571 ); 3572 toff += tinc; 3573 tinc = PAGE_SIZE; 3574 } 3575 VM_OBJECT_WUNLOCK(obj); 3576 3577 /* 3578 * Step 3, fixup the KVM pmap. 3579 */ 3580 if ((bp->b_flags & B_UNMAPPED) == 0) 3581 bpmap_qenter(bp); 3582 else 3583 BUF_CHECK_UNMAPPED(bp); 3584 } 3585 } 3586 if (newbsize < bp->b_bufsize) 3587 bufspacewakeup(); 3588 bp->b_bufsize = newbsize; /* actual buffer allocation */ 3589 bp->b_bcount = size; /* requested buffer size */ 3590 return 1; 3591 } 3592 3593 extern int inflight_transient_maps; 3594 3595 void 3596 biodone(struct bio *bp) 3597 { 3598 struct mtx *mtxp; 3599 void (*done)(struct bio *); 3600 vm_offset_t start, end; 3601 3602 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) { 3603 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING; 3604 bp->bio_flags |= BIO_UNMAPPED; 3605 start = trunc_page((vm_offset_t)bp->bio_data); 3606 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length); 3607 pmap_qremove(start, OFF_TO_IDX(end - start)); 3608 vmem_free(transient_arena, start, end - start); 3609 atomic_add_int(&inflight_transient_maps, -1); 3610 } 3611 done = bp->bio_done; 3612 if (done == NULL) { 3613 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3614 mtx_lock(mtxp); 3615 bp->bio_flags |= BIO_DONE; 3616 wakeup(bp); 3617 mtx_unlock(mtxp); 3618 } else { 3619 bp->bio_flags |= BIO_DONE; 3620 done(bp); 3621 } 3622 } 3623 3624 /* 3625 * Wait for a BIO to finish. 3626 */ 3627 int 3628 biowait(struct bio *bp, const char *wchan) 3629 { 3630 struct mtx *mtxp; 3631 3632 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3633 mtx_lock(mtxp); 3634 while ((bp->bio_flags & BIO_DONE) == 0) 3635 msleep(bp, mtxp, PRIBIO, wchan, 0); 3636 mtx_unlock(mtxp); 3637 if (bp->bio_error != 0) 3638 return (bp->bio_error); 3639 if (!(bp->bio_flags & BIO_ERROR)) 3640 return (0); 3641 return (EIO); 3642 } 3643 3644 void 3645 biofinish(struct bio *bp, struct devstat *stat, int error) 3646 { 3647 3648 if (error) { 3649 bp->bio_error = error; 3650 bp->bio_flags |= BIO_ERROR; 3651 } 3652 if (stat != NULL) 3653 devstat_end_transaction_bio(stat, bp); 3654 biodone(bp); 3655 } 3656 3657 /* 3658 * bufwait: 3659 * 3660 * Wait for buffer I/O completion, returning error status. The buffer 3661 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3662 * error and cleared. 3663 */ 3664 int 3665 bufwait(struct buf *bp) 3666 { 3667 if (bp->b_iocmd == BIO_READ) 3668 bwait(bp, PRIBIO, "biord"); 3669 else 3670 bwait(bp, PRIBIO, "biowr"); 3671 if (bp->b_flags & B_EINTR) { 3672 bp->b_flags &= ~B_EINTR; 3673 return (EINTR); 3674 } 3675 if (bp->b_ioflags & BIO_ERROR) { 3676 return (bp->b_error ? bp->b_error : EIO); 3677 } else { 3678 return (0); 3679 } 3680 } 3681 3682 /* 3683 * Call back function from struct bio back up to struct buf. 3684 */ 3685 static void 3686 bufdonebio(struct bio *bip) 3687 { 3688 struct buf *bp; 3689 3690 bp = bip->bio_caller2; 3691 bp->b_resid = bip->bio_resid; 3692 bp->b_ioflags = bip->bio_flags; 3693 bp->b_error = bip->bio_error; 3694 if (bp->b_error) 3695 bp->b_ioflags |= BIO_ERROR; 3696 bufdone(bp); 3697 g_destroy_bio(bip); 3698 } 3699 3700 void 3701 dev_strategy(struct cdev *dev, struct buf *bp) 3702 { 3703 struct cdevsw *csw; 3704 int ref; 3705 3706 KASSERT(dev->si_refcount > 0, 3707 ("dev_strategy on un-referenced struct cdev *(%s) %p", 3708 devtoname(dev), dev)); 3709 3710 csw = dev_refthread(dev, &ref); 3711 dev_strategy_csw(dev, csw, bp); 3712 dev_relthread(dev, ref); 3713 } 3714 3715 void 3716 dev_strategy_csw(struct cdev *dev, struct cdevsw *csw, struct buf *bp) 3717 { 3718 struct bio *bip; 3719 3720 KASSERT(bp->b_iocmd == BIO_READ || bp->b_iocmd == BIO_WRITE, 3721 ("b_iocmd botch")); 3722 KASSERT(((dev->si_flags & SI_ETERNAL) != 0 && csw != NULL) || 3723 dev->si_threadcount > 0, 3724 ("dev_strategy_csw threadcount cdev *(%s) %p", devtoname(dev), 3725 dev)); 3726 if (csw == NULL) { 3727 bp->b_error = ENXIO; 3728 bp->b_ioflags = BIO_ERROR; 3729 bufdone(bp); 3730 return; 3731 } 3732 for (;;) { 3733 bip = g_new_bio(); 3734 if (bip != NULL) 3735 break; 3736 /* Try again later */ 3737 tsleep(&bp, PRIBIO, "dev_strat", hz/10); 3738 } 3739 bip->bio_cmd = bp->b_iocmd; 3740 bip->bio_offset = bp->b_iooffset; 3741 bip->bio_length = bp->b_bcount; 3742 bip->bio_bcount = bp->b_bcount; /* XXX: remove */ 3743 bdata2bio(bp, bip); 3744 bip->bio_done = bufdonebio; 3745 bip->bio_caller2 = bp; 3746 bip->bio_dev = dev; 3747 (*csw->d_strategy)(bip); 3748 } 3749 3750 /* 3751 * bufdone: 3752 * 3753 * Finish I/O on a buffer, optionally calling a completion function. 3754 * This is usually called from an interrupt so process blocking is 3755 * not allowed. 3756 * 3757 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3758 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3759 * assuming B_INVAL is clear. 3760 * 3761 * For the VMIO case, we set B_CACHE if the op was a read and no 3762 * read error occured, or if the op was a write. B_CACHE is never 3763 * set if the buffer is invalid or otherwise uncacheable. 3764 * 3765 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3766 * initiator to leave B_INVAL set to brelse the buffer out of existance 3767 * in the biodone routine. 3768 */ 3769 void 3770 bufdone(struct buf *bp) 3771 { 3772 struct bufobj *dropobj; 3773 void (*biodone)(struct buf *); 3774 3775 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 3776 dropobj = NULL; 3777 3778 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 3779 BUF_ASSERT_HELD(bp); 3780 3781 runningbufwakeup(bp); 3782 if (bp->b_iocmd == BIO_WRITE) 3783 dropobj = bp->b_bufobj; 3784 /* call optional completion function if requested */ 3785 if (bp->b_iodone != NULL) { 3786 biodone = bp->b_iodone; 3787 bp->b_iodone = NULL; 3788 (*biodone) (bp); 3789 if (dropobj) 3790 bufobj_wdrop(dropobj); 3791 return; 3792 } 3793 3794 bufdone_finish(bp); 3795 3796 if (dropobj) 3797 bufobj_wdrop(dropobj); 3798 } 3799 3800 void 3801 bufdone_finish(struct buf *bp) 3802 { 3803 BUF_ASSERT_HELD(bp); 3804 3805 if (!LIST_EMPTY(&bp->b_dep)) 3806 buf_complete(bp); 3807 3808 if (bp->b_flags & B_VMIO) { 3809 vm_ooffset_t foff; 3810 vm_page_t m; 3811 vm_object_t obj; 3812 struct vnode *vp; 3813 int bogus, i, iosize; 3814 3815 obj = bp->b_bufobj->bo_object; 3816 KASSERT(obj->paging_in_progress >= bp->b_npages, 3817 ("biodone_finish: paging in progress(%d) < b_npages(%d)", 3818 obj->paging_in_progress, bp->b_npages)); 3819 3820 vp = bp->b_vp; 3821 KASSERT(vp->v_holdcnt > 0, 3822 ("biodone_finish: vnode %p has zero hold count", vp)); 3823 KASSERT(vp->v_object != NULL, 3824 ("biodone_finish: vnode %p has no vm_object", vp)); 3825 3826 foff = bp->b_offset; 3827 KASSERT(bp->b_offset != NOOFFSET, 3828 ("biodone_finish: bp %p has no buffer offset", bp)); 3829 3830 /* 3831 * Set B_CACHE if the op was a normal read and no error 3832 * occured. B_CACHE is set for writes in the b*write() 3833 * routines. 3834 */ 3835 iosize = bp->b_bcount - bp->b_resid; 3836 if (bp->b_iocmd == BIO_READ && 3837 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 3838 !(bp->b_ioflags & BIO_ERROR)) { 3839 bp->b_flags |= B_CACHE; 3840 } 3841 bogus = 0; 3842 VM_OBJECT_WLOCK(obj); 3843 for (i = 0; i < bp->b_npages; i++) { 3844 int bogusflag = 0; 3845 int resid; 3846 3847 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 3848 if (resid > iosize) 3849 resid = iosize; 3850 3851 /* 3852 * cleanup bogus pages, restoring the originals 3853 */ 3854 m = bp->b_pages[i]; 3855 if (m == bogus_page) { 3856 bogus = bogusflag = 1; 3857 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3858 if (m == NULL) 3859 panic("biodone: page disappeared!"); 3860 bp->b_pages[i] = m; 3861 } 3862 KASSERT(OFF_TO_IDX(foff) == m->pindex, 3863 ("biodone_finish: foff(%jd)/pindex(%ju) mismatch", 3864 (intmax_t)foff, (uintmax_t)m->pindex)); 3865 3866 /* 3867 * In the write case, the valid and clean bits are 3868 * already changed correctly ( see bdwrite() ), so we 3869 * only need to do this here in the read case. 3870 */ 3871 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 3872 KASSERT((m->dirty & vm_page_bits(foff & 3873 PAGE_MASK, resid)) == 0, ("bufdone_finish:" 3874 " page %p has unexpected dirty bits", m)); 3875 vfs_page_set_valid(bp, foff, m); 3876 } 3877 3878 vm_page_sunbusy(m); 3879 vm_object_pip_subtract(obj, 1); 3880 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3881 iosize -= resid; 3882 } 3883 vm_object_pip_wakeupn(obj, 0); 3884 VM_OBJECT_WUNLOCK(obj); 3885 if (bogus && (bp->b_flags & B_UNMAPPED) == 0) { 3886 BUF_CHECK_MAPPED(bp); 3887 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3888 bp->b_pages, bp->b_npages); 3889 } 3890 } 3891 3892 /* 3893 * For asynchronous completions, release the buffer now. The brelse 3894 * will do a wakeup there if necessary - so no need to do a wakeup 3895 * here in the async case. The sync case always needs to do a wakeup. 3896 */ 3897 3898 if (bp->b_flags & B_ASYNC) { 3899 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 3900 brelse(bp); 3901 else 3902 bqrelse(bp); 3903 } else 3904 bdone(bp); 3905 } 3906 3907 /* 3908 * This routine is called in lieu of iodone in the case of 3909 * incomplete I/O. This keeps the busy status for pages 3910 * consistant. 3911 */ 3912 void 3913 vfs_unbusy_pages(struct buf *bp) 3914 { 3915 int i; 3916 vm_object_t obj; 3917 vm_page_t m; 3918 3919 runningbufwakeup(bp); 3920 if (!(bp->b_flags & B_VMIO)) 3921 return; 3922 3923 obj = bp->b_bufobj->bo_object; 3924 VM_OBJECT_WLOCK(obj); 3925 for (i = 0; i < bp->b_npages; i++) { 3926 m = bp->b_pages[i]; 3927 if (m == bogus_page) { 3928 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 3929 if (!m) 3930 panic("vfs_unbusy_pages: page missing\n"); 3931 bp->b_pages[i] = m; 3932 if ((bp->b_flags & B_UNMAPPED) == 0) { 3933 BUF_CHECK_MAPPED(bp); 3934 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3935 bp->b_pages, bp->b_npages); 3936 } else 3937 BUF_CHECK_UNMAPPED(bp); 3938 } 3939 vm_object_pip_subtract(obj, 1); 3940 vm_page_sunbusy(m); 3941 } 3942 vm_object_pip_wakeupn(obj, 0); 3943 VM_OBJECT_WUNLOCK(obj); 3944 } 3945 3946 /* 3947 * vfs_page_set_valid: 3948 * 3949 * Set the valid bits in a page based on the supplied offset. The 3950 * range is restricted to the buffer's size. 3951 * 3952 * This routine is typically called after a read completes. 3953 */ 3954 static void 3955 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3956 { 3957 vm_ooffset_t eoff; 3958 3959 /* 3960 * Compute the end offset, eoff, such that [off, eoff) does not span a 3961 * page boundary and eoff is not greater than the end of the buffer. 3962 * The end of the buffer, in this case, is our file EOF, not the 3963 * allocation size of the buffer. 3964 */ 3965 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 3966 if (eoff > bp->b_offset + bp->b_bcount) 3967 eoff = bp->b_offset + bp->b_bcount; 3968 3969 /* 3970 * Set valid range. This is typically the entire buffer and thus the 3971 * entire page. 3972 */ 3973 if (eoff > off) 3974 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off); 3975 } 3976 3977 /* 3978 * vfs_page_set_validclean: 3979 * 3980 * Set the valid bits and clear the dirty bits in a page based on the 3981 * supplied offset. The range is restricted to the buffer's size. 3982 */ 3983 static void 3984 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3985 { 3986 vm_ooffset_t soff, eoff; 3987 3988 /* 3989 * Start and end offsets in buffer. eoff - soff may not cross a 3990 * page boundry or cross the end of the buffer. The end of the 3991 * buffer, in this case, is our file EOF, not the allocation size 3992 * of the buffer. 3993 */ 3994 soff = off; 3995 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3996 if (eoff > bp->b_offset + bp->b_bcount) 3997 eoff = bp->b_offset + bp->b_bcount; 3998 3999 /* 4000 * Set valid range. This is typically the entire buffer and thus the 4001 * entire page. 4002 */ 4003 if (eoff > soff) { 4004 vm_page_set_validclean( 4005 m, 4006 (vm_offset_t) (soff & PAGE_MASK), 4007 (vm_offset_t) (eoff - soff) 4008 ); 4009 } 4010 } 4011 4012 /* 4013 * Ensure that all buffer pages are not exclusive busied. If any page is 4014 * exclusive busy, drain it. 4015 */ 4016 void 4017 vfs_drain_busy_pages(struct buf *bp) 4018 { 4019 vm_page_t m; 4020 int i, last_busied; 4021 4022 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object); 4023 last_busied = 0; 4024 for (i = 0; i < bp->b_npages; i++) { 4025 m = bp->b_pages[i]; 4026 if (vm_page_xbusied(m)) { 4027 for (; last_busied < i; last_busied++) 4028 vm_page_sbusy(bp->b_pages[last_busied]); 4029 while (vm_page_xbusied(m)) { 4030 vm_page_lock(m); 4031 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4032 vm_page_busy_sleep(m, "vbpage"); 4033 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4034 } 4035 } 4036 } 4037 for (i = 0; i < last_busied; i++) 4038 vm_page_sunbusy(bp->b_pages[i]); 4039 } 4040 4041 /* 4042 * This routine is called before a device strategy routine. 4043 * It is used to tell the VM system that paging I/O is in 4044 * progress, and treat the pages associated with the buffer 4045 * almost as being exclusive busy. Also the object paging_in_progress 4046 * flag is handled to make sure that the object doesn't become 4047 * inconsistant. 4048 * 4049 * Since I/O has not been initiated yet, certain buffer flags 4050 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 4051 * and should be ignored. 4052 */ 4053 void 4054 vfs_busy_pages(struct buf *bp, int clear_modify) 4055 { 4056 int i, bogus; 4057 vm_object_t obj; 4058 vm_ooffset_t foff; 4059 vm_page_t m; 4060 4061 if (!(bp->b_flags & B_VMIO)) 4062 return; 4063 4064 obj = bp->b_bufobj->bo_object; 4065 foff = bp->b_offset; 4066 KASSERT(bp->b_offset != NOOFFSET, 4067 ("vfs_busy_pages: no buffer offset")); 4068 VM_OBJECT_WLOCK(obj); 4069 vfs_drain_busy_pages(bp); 4070 if (bp->b_bufsize != 0) 4071 vfs_setdirty_locked_object(bp); 4072 bogus = 0; 4073 for (i = 0; i < bp->b_npages; i++) { 4074 m = bp->b_pages[i]; 4075 4076 if ((bp->b_flags & B_CLUSTER) == 0) { 4077 vm_object_pip_add(obj, 1); 4078 vm_page_sbusy(m); 4079 } 4080 /* 4081 * When readying a buffer for a read ( i.e 4082 * clear_modify == 0 ), it is important to do 4083 * bogus_page replacement for valid pages in 4084 * partially instantiated buffers. Partially 4085 * instantiated buffers can, in turn, occur when 4086 * reconstituting a buffer from its VM backing store 4087 * base. We only have to do this if B_CACHE is 4088 * clear ( which causes the I/O to occur in the 4089 * first place ). The replacement prevents the read 4090 * I/O from overwriting potentially dirty VM-backed 4091 * pages. XXX bogus page replacement is, uh, bogus. 4092 * It may not work properly with small-block devices. 4093 * We need to find a better way. 4094 */ 4095 if (clear_modify) { 4096 pmap_remove_write(m); 4097 vfs_page_set_validclean(bp, foff, m); 4098 } else if (m->valid == VM_PAGE_BITS_ALL && 4099 (bp->b_flags & B_CACHE) == 0) { 4100 bp->b_pages[i] = bogus_page; 4101 bogus++; 4102 } 4103 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4104 } 4105 VM_OBJECT_WUNLOCK(obj); 4106 if (bogus && (bp->b_flags & B_UNMAPPED) == 0) { 4107 BUF_CHECK_MAPPED(bp); 4108 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4109 bp->b_pages, bp->b_npages); 4110 } 4111 } 4112 4113 /* 4114 * vfs_bio_set_valid: 4115 * 4116 * Set the range within the buffer to valid. The range is 4117 * relative to the beginning of the buffer, b_offset. Note that 4118 * b_offset itself may be offset from the beginning of the first 4119 * page. 4120 */ 4121 void 4122 vfs_bio_set_valid(struct buf *bp, int base, int size) 4123 { 4124 int i, n; 4125 vm_page_t m; 4126 4127 if (!(bp->b_flags & B_VMIO)) 4128 return; 4129 4130 /* 4131 * Fixup base to be relative to beginning of first page. 4132 * Set initial n to be the maximum number of bytes in the 4133 * first page that can be validated. 4134 */ 4135 base += (bp->b_offset & PAGE_MASK); 4136 n = PAGE_SIZE - (base & PAGE_MASK); 4137 4138 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4139 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4140 m = bp->b_pages[i]; 4141 if (n > size) 4142 n = size; 4143 vm_page_set_valid_range(m, base & PAGE_MASK, n); 4144 base += n; 4145 size -= n; 4146 n = PAGE_SIZE; 4147 } 4148 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4149 } 4150 4151 /* 4152 * vfs_bio_clrbuf: 4153 * 4154 * If the specified buffer is a non-VMIO buffer, clear the entire 4155 * buffer. If the specified buffer is a VMIO buffer, clear and 4156 * validate only the previously invalid portions of the buffer. 4157 * This routine essentially fakes an I/O, so we need to clear 4158 * BIO_ERROR and B_INVAL. 4159 * 4160 * Note that while we only theoretically need to clear through b_bcount, 4161 * we go ahead and clear through b_bufsize. 4162 */ 4163 void 4164 vfs_bio_clrbuf(struct buf *bp) 4165 { 4166 int i, j, mask, sa, ea, slide; 4167 4168 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 4169 clrbuf(bp); 4170 return; 4171 } 4172 bp->b_flags &= ~B_INVAL; 4173 bp->b_ioflags &= ~BIO_ERROR; 4174 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4175 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 4176 (bp->b_offset & PAGE_MASK) == 0) { 4177 if (bp->b_pages[0] == bogus_page) 4178 goto unlock; 4179 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 4180 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object); 4181 if ((bp->b_pages[0]->valid & mask) == mask) 4182 goto unlock; 4183 if ((bp->b_pages[0]->valid & mask) == 0) { 4184 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize); 4185 bp->b_pages[0]->valid |= mask; 4186 goto unlock; 4187 } 4188 } 4189 sa = bp->b_offset & PAGE_MASK; 4190 slide = 0; 4191 for (i = 0; i < bp->b_npages; i++, sa = 0) { 4192 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize); 4193 ea = slide & PAGE_MASK; 4194 if (ea == 0) 4195 ea = PAGE_SIZE; 4196 if (bp->b_pages[i] == bogus_page) 4197 continue; 4198 j = sa / DEV_BSIZE; 4199 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 4200 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object); 4201 if ((bp->b_pages[i]->valid & mask) == mask) 4202 continue; 4203 if ((bp->b_pages[i]->valid & mask) == 0) 4204 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa); 4205 else { 4206 for (; sa < ea; sa += DEV_BSIZE, j++) { 4207 if ((bp->b_pages[i]->valid & (1 << j)) == 0) { 4208 pmap_zero_page_area(bp->b_pages[i], 4209 sa, DEV_BSIZE); 4210 } 4211 } 4212 } 4213 bp->b_pages[i]->valid |= mask; 4214 } 4215 unlock: 4216 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4217 bp->b_resid = 0; 4218 } 4219 4220 void 4221 vfs_bio_bzero_buf(struct buf *bp, int base, int size) 4222 { 4223 vm_page_t m; 4224 int i, n; 4225 4226 if ((bp->b_flags & B_UNMAPPED) == 0) { 4227 BUF_CHECK_MAPPED(bp); 4228 bzero(bp->b_data + base, size); 4229 } else { 4230 BUF_CHECK_UNMAPPED(bp); 4231 n = PAGE_SIZE - (base & PAGE_MASK); 4232 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4233 m = bp->b_pages[i]; 4234 if (n > size) 4235 n = size; 4236 pmap_zero_page_area(m, base & PAGE_MASK, n); 4237 base += n; 4238 size -= n; 4239 n = PAGE_SIZE; 4240 } 4241 } 4242 } 4243 4244 /* 4245 * vm_hold_load_pages and vm_hold_free_pages get pages into 4246 * a buffers address space. The pages are anonymous and are 4247 * not associated with a file object. 4248 */ 4249 static void 4250 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4251 { 4252 vm_offset_t pg; 4253 vm_page_t p; 4254 int index; 4255 4256 BUF_CHECK_MAPPED(bp); 4257 4258 to = round_page(to); 4259 from = round_page(from); 4260 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4261 4262 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 4263 tryagain: 4264 /* 4265 * note: must allocate system pages since blocking here 4266 * could interfere with paging I/O, no matter which 4267 * process we are. 4268 */ 4269 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ | 4270 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT)); 4271 if (p == NULL) { 4272 VM_WAIT; 4273 goto tryagain; 4274 } 4275 pmap_qenter(pg, &p, 1); 4276 bp->b_pages[index] = p; 4277 } 4278 bp->b_npages = index; 4279 } 4280 4281 /* Return pages associated with this buf to the vm system */ 4282 static void 4283 vm_hold_free_pages(struct buf *bp, int newbsize) 4284 { 4285 vm_offset_t from; 4286 vm_page_t p; 4287 int index, newnpages; 4288 4289 BUF_CHECK_MAPPED(bp); 4290 4291 from = round_page((vm_offset_t)bp->b_data + newbsize); 4292 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4293 if (bp->b_npages > newnpages) 4294 pmap_qremove(from, bp->b_npages - newnpages); 4295 for (index = newnpages; index < bp->b_npages; index++) { 4296 p = bp->b_pages[index]; 4297 bp->b_pages[index] = NULL; 4298 if (vm_page_sbusied(p)) 4299 printf("vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 4300 (intmax_t)bp->b_blkno, (intmax_t)bp->b_lblkno); 4301 p->wire_count--; 4302 vm_page_free(p); 4303 atomic_subtract_int(&vm_cnt.v_wire_count, 1); 4304 } 4305 bp->b_npages = newnpages; 4306 } 4307 4308 /* 4309 * Map an IO request into kernel virtual address space. 4310 * 4311 * All requests are (re)mapped into kernel VA space. 4312 * Notice that we use b_bufsize for the size of the buffer 4313 * to be mapped. b_bcount might be modified by the driver. 4314 * 4315 * Note that even if the caller determines that the address space should 4316 * be valid, a race or a smaller-file mapped into a larger space may 4317 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 4318 * check the return value. 4319 */ 4320 int 4321 vmapbuf(struct buf *bp, int mapbuf) 4322 { 4323 caddr_t kva; 4324 vm_prot_t prot; 4325 int pidx; 4326 4327 if (bp->b_bufsize < 0) 4328 return (-1); 4329 prot = VM_PROT_READ; 4330 if (bp->b_iocmd == BIO_READ) 4331 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 4332 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 4333 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages, 4334 btoc(MAXPHYS))) < 0) 4335 return (-1); 4336 bp->b_npages = pidx; 4337 if (mapbuf || !unmapped_buf_allowed) { 4338 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx); 4339 kva = bp->b_saveaddr; 4340 bp->b_saveaddr = bp->b_data; 4341 bp->b_data = kva + (((vm_offset_t)bp->b_data) & PAGE_MASK); 4342 bp->b_flags &= ~B_UNMAPPED; 4343 } else { 4344 bp->b_flags |= B_UNMAPPED; 4345 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK; 4346 bp->b_saveaddr = bp->b_data; 4347 bp->b_data = unmapped_buf; 4348 } 4349 return(0); 4350 } 4351 4352 /* 4353 * Free the io map PTEs associated with this IO operation. 4354 * We also invalidate the TLB entries and restore the original b_addr. 4355 */ 4356 void 4357 vunmapbuf(struct buf *bp) 4358 { 4359 int npages; 4360 4361 npages = bp->b_npages; 4362 if (bp->b_flags & B_UNMAPPED) 4363 bp->b_flags &= ~B_UNMAPPED; 4364 else 4365 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 4366 vm_page_unhold_pages(bp->b_pages, npages); 4367 4368 bp->b_data = bp->b_saveaddr; 4369 } 4370 4371 void 4372 bdone(struct buf *bp) 4373 { 4374 struct mtx *mtxp; 4375 4376 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4377 mtx_lock(mtxp); 4378 bp->b_flags |= B_DONE; 4379 wakeup(bp); 4380 mtx_unlock(mtxp); 4381 } 4382 4383 void 4384 bwait(struct buf *bp, u_char pri, const char *wchan) 4385 { 4386 struct mtx *mtxp; 4387 4388 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4389 mtx_lock(mtxp); 4390 while ((bp->b_flags & B_DONE) == 0) 4391 msleep(bp, mtxp, pri, wchan, 0); 4392 mtx_unlock(mtxp); 4393 } 4394 4395 int 4396 bufsync(struct bufobj *bo, int waitfor) 4397 { 4398 4399 return (VOP_FSYNC(bo->__bo_vnode, waitfor, curthread)); 4400 } 4401 4402 void 4403 bufstrategy(struct bufobj *bo, struct buf *bp) 4404 { 4405 int i = 0; 4406 struct vnode *vp; 4407 4408 vp = bp->b_vp; 4409 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 4410 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 4411 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 4412 i = VOP_STRATEGY(vp, bp); 4413 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 4414 } 4415 4416 void 4417 bufobj_wrefl(struct bufobj *bo) 4418 { 4419 4420 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4421 ASSERT_BO_WLOCKED(bo); 4422 bo->bo_numoutput++; 4423 } 4424 4425 void 4426 bufobj_wref(struct bufobj *bo) 4427 { 4428 4429 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4430 BO_LOCK(bo); 4431 bo->bo_numoutput++; 4432 BO_UNLOCK(bo); 4433 } 4434 4435 void 4436 bufobj_wdrop(struct bufobj *bo) 4437 { 4438 4439 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 4440 BO_LOCK(bo); 4441 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 4442 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 4443 bo->bo_flag &= ~BO_WWAIT; 4444 wakeup(&bo->bo_numoutput); 4445 } 4446 BO_UNLOCK(bo); 4447 } 4448 4449 int 4450 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 4451 { 4452 int error; 4453 4454 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 4455 ASSERT_BO_WLOCKED(bo); 4456 error = 0; 4457 while (bo->bo_numoutput) { 4458 bo->bo_flag |= BO_WWAIT; 4459 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo), 4460 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 4461 if (error) 4462 break; 4463 } 4464 return (error); 4465 } 4466 4467 void 4468 bpin(struct buf *bp) 4469 { 4470 struct mtx *mtxp; 4471 4472 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4473 mtx_lock(mtxp); 4474 bp->b_pin_count++; 4475 mtx_unlock(mtxp); 4476 } 4477 4478 void 4479 bunpin(struct buf *bp) 4480 { 4481 struct mtx *mtxp; 4482 4483 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4484 mtx_lock(mtxp); 4485 if (--bp->b_pin_count == 0) 4486 wakeup(bp); 4487 mtx_unlock(mtxp); 4488 } 4489 4490 void 4491 bunpin_wait(struct buf *bp) 4492 { 4493 struct mtx *mtxp; 4494 4495 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4496 mtx_lock(mtxp); 4497 while (bp->b_pin_count > 0) 4498 msleep(bp, mtxp, PRIBIO, "bwunpin", 0); 4499 mtx_unlock(mtxp); 4500 } 4501 4502 /* 4503 * Set bio_data or bio_ma for struct bio from the struct buf. 4504 */ 4505 void 4506 bdata2bio(struct buf *bp, struct bio *bip) 4507 { 4508 4509 if ((bp->b_flags & B_UNMAPPED) != 0) { 4510 KASSERT(unmapped_buf_allowed, ("unmapped")); 4511 bip->bio_ma = bp->b_pages; 4512 bip->bio_ma_n = bp->b_npages; 4513 bip->bio_data = unmapped_buf; 4514 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 4515 bip->bio_flags |= BIO_UNMAPPED; 4516 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) / 4517 PAGE_SIZE == bp->b_npages, 4518 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset, 4519 (long long)bip->bio_length, bip->bio_ma_n)); 4520 } else { 4521 bip->bio_data = bp->b_data; 4522 bip->bio_ma = NULL; 4523 } 4524 } 4525 4526 #include "opt_ddb.h" 4527 #ifdef DDB 4528 #include <ddb/ddb.h> 4529 4530 /* DDB command to show buffer data */ 4531 DB_SHOW_COMMAND(buffer, db_show_buffer) 4532 { 4533 /* get args */ 4534 struct buf *bp = (struct buf *)addr; 4535 4536 if (!have_addr) { 4537 db_printf("usage: show buffer <addr>\n"); 4538 return; 4539 } 4540 4541 db_printf("buf at %p\n", bp); 4542 db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n", 4543 (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags, 4544 PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS); 4545 db_printf( 4546 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 4547 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, " 4548 "b_dep = %p\n", 4549 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 4550 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 4551 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first); 4552 if (bp->b_npages) { 4553 int i; 4554 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 4555 for (i = 0; i < bp->b_npages; i++) { 4556 vm_page_t m; 4557 m = bp->b_pages[i]; 4558 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 4559 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 4560 if ((i + 1) < bp->b_npages) 4561 db_printf(","); 4562 } 4563 db_printf("\n"); 4564 } 4565 db_printf(" "); 4566 BUF_LOCKPRINTINFO(bp); 4567 } 4568 4569 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 4570 { 4571 struct buf *bp; 4572 int i; 4573 4574 for (i = 0; i < nbuf; i++) { 4575 bp = &buf[i]; 4576 if (BUF_ISLOCKED(bp)) { 4577 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4578 db_printf("\n"); 4579 } 4580 } 4581 } 4582 4583 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 4584 { 4585 struct vnode *vp; 4586 struct buf *bp; 4587 4588 if (!have_addr) { 4589 db_printf("usage: show vnodebufs <addr>\n"); 4590 return; 4591 } 4592 vp = (struct vnode *)addr; 4593 db_printf("Clean buffers:\n"); 4594 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 4595 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4596 db_printf("\n"); 4597 } 4598 db_printf("Dirty buffers:\n"); 4599 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 4600 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4601 db_printf("\n"); 4602 } 4603 } 4604 4605 DB_COMMAND(countfreebufs, db_coundfreebufs) 4606 { 4607 struct buf *bp; 4608 int i, used = 0, nfree = 0; 4609 4610 if (have_addr) { 4611 db_printf("usage: countfreebufs\n"); 4612 return; 4613 } 4614 4615 for (i = 0; i < nbuf; i++) { 4616 bp = &buf[i]; 4617 if ((bp->b_flags & B_INFREECNT) != 0) 4618 nfree++; 4619 else 4620 used++; 4621 } 4622 4623 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 4624 nfree + used); 4625 db_printf("numfreebuffers is %d\n", numfreebuffers); 4626 } 4627 #endif /* DDB */ 4628