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