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 vm_object_t obj; 1887 vm_page_t m; 1888 int i; 1889 1890 if ((bp->b_flags & B_UNMAPPED) == 0) { 1891 BUF_CHECK_MAPPED(bp); 1892 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages); 1893 } else 1894 BUF_CHECK_UNMAPPED(bp); 1895 obj = bp->b_bufobj->bo_object; 1896 if (obj != NULL) 1897 VM_OBJECT_WLOCK(obj); 1898 for (i = 0; i < bp->b_npages; i++) { 1899 m = bp->b_pages[i]; 1900 bp->b_pages[i] = NULL; 1901 /* 1902 * In order to keep page LRU ordering consistent, put 1903 * everything on the inactive queue. 1904 */ 1905 vm_page_lock(m); 1906 vm_page_unwire(m, PQ_INACTIVE); 1907 1908 /* 1909 * Might as well free the page if we can and it has 1910 * no valid data. We also free the page if the 1911 * buffer was used for direct I/O 1912 */ 1913 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid) { 1914 if (m->wire_count == 0 && !vm_page_busied(m)) 1915 vm_page_free(m); 1916 } else if (bp->b_flags & B_DIRECT) 1917 vm_page_try_to_free(m); 1918 else if (buf_vm_page_count_severe()) 1919 vm_page_try_to_cache(m); 1920 vm_page_unlock(m); 1921 } 1922 if (obj != NULL) 1923 VM_OBJECT_WUNLOCK(obj); 1924 1925 if (bp->b_bufsize) { 1926 bufspacewakeup(); 1927 bp->b_bufsize = 0; 1928 } 1929 bp->b_npages = 0; 1930 bp->b_flags &= ~B_VMIO; 1931 if (bp->b_vp) 1932 brelvp(bp); 1933 } 1934 1935 /* 1936 * Check to see if a block at a particular lbn is available for a clustered 1937 * write. 1938 */ 1939 static int 1940 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 1941 { 1942 struct buf *bpa; 1943 int match; 1944 1945 match = 0; 1946 1947 /* If the buf isn't in core skip it */ 1948 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 1949 return (0); 1950 1951 /* If the buf is busy we don't want to wait for it */ 1952 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1953 return (0); 1954 1955 /* Only cluster with valid clusterable delayed write buffers */ 1956 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 1957 (B_DELWRI | B_CLUSTEROK)) 1958 goto done; 1959 1960 if (bpa->b_bufsize != size) 1961 goto done; 1962 1963 /* 1964 * Check to see if it is in the expected place on disk and that the 1965 * block has been mapped. 1966 */ 1967 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 1968 match = 1; 1969 done: 1970 BUF_UNLOCK(bpa); 1971 return (match); 1972 } 1973 1974 /* 1975 * vfs_bio_awrite: 1976 * 1977 * Implement clustered async writes for clearing out B_DELWRI buffers. 1978 * This is much better then the old way of writing only one buffer at 1979 * a time. Note that we may not be presented with the buffers in the 1980 * correct order, so we search for the cluster in both directions. 1981 */ 1982 int 1983 vfs_bio_awrite(struct buf *bp) 1984 { 1985 struct bufobj *bo; 1986 int i; 1987 int j; 1988 daddr_t lblkno = bp->b_lblkno; 1989 struct vnode *vp = bp->b_vp; 1990 int ncl; 1991 int nwritten; 1992 int size; 1993 int maxcl; 1994 int gbflags; 1995 1996 bo = &vp->v_bufobj; 1997 gbflags = (bp->b_flags & B_UNMAPPED) != 0 ? GB_UNMAPPED : 0; 1998 /* 1999 * right now we support clustered writing only to regular files. If 2000 * we find a clusterable block we could be in the middle of a cluster 2001 * rather then at the beginning. 2002 */ 2003 if ((vp->v_type == VREG) && 2004 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 2005 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 2006 2007 size = vp->v_mount->mnt_stat.f_iosize; 2008 maxcl = MAXPHYS / size; 2009 2010 BO_RLOCK(bo); 2011 for (i = 1; i < maxcl; i++) 2012 if (vfs_bio_clcheck(vp, size, lblkno + i, 2013 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 2014 break; 2015 2016 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 2017 if (vfs_bio_clcheck(vp, size, lblkno - j, 2018 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 2019 break; 2020 BO_RUNLOCK(bo); 2021 --j; 2022 ncl = i + j; 2023 /* 2024 * this is a possible cluster write 2025 */ 2026 if (ncl != 1) { 2027 BUF_UNLOCK(bp); 2028 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl, 2029 gbflags); 2030 return (nwritten); 2031 } 2032 } 2033 bremfree(bp); 2034 bp->b_flags |= B_ASYNC; 2035 /* 2036 * default (old) behavior, writing out only one block 2037 * 2038 * XXX returns b_bufsize instead of b_bcount for nwritten? 2039 */ 2040 nwritten = bp->b_bufsize; 2041 (void) bwrite(bp); 2042 2043 return (nwritten); 2044 } 2045 2046 static void 2047 setbufkva(struct buf *bp, vm_offset_t addr, int maxsize, int gbflags) 2048 { 2049 2050 KASSERT((bp->b_flags & (B_UNMAPPED | B_KVAALLOC)) == 0 && 2051 bp->b_kvasize == 0, ("call bfreekva(%p)", bp)); 2052 if ((gbflags & GB_UNMAPPED) == 0) { 2053 bp->b_kvabase = (caddr_t)addr; 2054 } else if ((gbflags & GB_KVAALLOC) != 0) { 2055 KASSERT((gbflags & GB_UNMAPPED) != 0, 2056 ("GB_KVAALLOC without GB_UNMAPPED")); 2057 bp->b_kvaalloc = (caddr_t)addr; 2058 bp->b_flags |= B_UNMAPPED | B_KVAALLOC; 2059 atomic_add_long(&unmapped_bufspace, bp->b_kvasize); 2060 } 2061 bp->b_kvasize = maxsize; 2062 } 2063 2064 /* 2065 * Allocate the buffer KVA and set b_kvasize. Also set b_kvabase if 2066 * needed. 2067 */ 2068 static int 2069 allocbufkva(struct buf *bp, int maxsize, int gbflags) 2070 { 2071 vm_offset_t addr; 2072 2073 bfreekva(bp); 2074 addr = 0; 2075 2076 if (vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr)) { 2077 /* 2078 * Buffer map is too fragmented. Request the caller 2079 * to defragment the map. 2080 */ 2081 atomic_add_int(&bufdefragcnt, 1); 2082 return (1); 2083 } 2084 setbufkva(bp, addr, maxsize, gbflags); 2085 atomic_add_long(&bufspace, bp->b_kvasize); 2086 return (0); 2087 } 2088 2089 /* 2090 * Ask the bufdaemon for help, or act as bufdaemon itself, when a 2091 * locked vnode is supplied. 2092 */ 2093 static void 2094 getnewbuf_bufd_help(struct vnode *vp, int gbflags, int slpflag, int slptimeo, 2095 int defrag) 2096 { 2097 struct thread *td; 2098 char *waitmsg; 2099 int cnt, error, flags, norunbuf, wait; 2100 2101 mtx_assert(&bqclean, MA_OWNED); 2102 2103 if (defrag) { 2104 flags = VFS_BIO_NEED_BUFSPACE; 2105 waitmsg = "nbufkv"; 2106 } else if (bufspace >= hibufspace) { 2107 waitmsg = "nbufbs"; 2108 flags = VFS_BIO_NEED_BUFSPACE; 2109 } else { 2110 waitmsg = "newbuf"; 2111 flags = VFS_BIO_NEED_ANY; 2112 } 2113 atomic_set_int(&needsbuffer, flags); 2114 mtx_unlock(&bqclean); 2115 2116 bd_speedup(); /* heeeelp */ 2117 if ((gbflags & GB_NOWAIT_BD) != 0) 2118 return; 2119 2120 td = curthread; 2121 cnt = 0; 2122 wait = MNT_NOWAIT; 2123 rw_wlock(&nblock); 2124 while ((needsbuffer & flags) != 0) { 2125 if (vp != NULL && vp->v_type != VCHR && 2126 (td->td_pflags & TDP_BUFNEED) == 0) { 2127 rw_wunlock(&nblock); 2128 /* 2129 * getblk() is called with a vnode locked, and 2130 * some majority of the dirty buffers may as 2131 * well belong to the vnode. Flushing the 2132 * buffers there would make a progress that 2133 * cannot be achieved by the buf_daemon, that 2134 * cannot lock the vnode. 2135 */ 2136 if (cnt++ > 2) 2137 wait = MNT_WAIT; 2138 ASSERT_VOP_LOCKED(vp, "bufd_helper"); 2139 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 : 2140 vn_lock(vp, LK_TRYUPGRADE); 2141 if (error == 0) { 2142 /* play bufdaemon */ 2143 norunbuf = curthread_pflags_set(TDP_BUFNEED | 2144 TDP_NORUNNINGBUF); 2145 VOP_FSYNC(vp, wait, td); 2146 atomic_add_long(¬bufdflushes, 1); 2147 curthread_pflags_restore(norunbuf); 2148 } 2149 rw_wlock(&nblock); 2150 if ((needsbuffer & flags) == 0) 2151 break; 2152 } 2153 error = rw_sleep(__DEVOLATILE(void *, &needsbuffer), &nblock, 2154 (PRIBIO + 4) | slpflag, waitmsg, slptimeo); 2155 if (error != 0) 2156 break; 2157 } 2158 rw_wunlock(&nblock); 2159 } 2160 2161 static void 2162 getnewbuf_reuse_bp(struct buf *bp, int qindex) 2163 { 2164 2165 CTR6(KTR_BUF, "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d " 2166 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags, 2167 bp->b_kvasize, bp->b_bufsize, qindex); 2168 mtx_assert(&bqclean, MA_NOTOWNED); 2169 2170 /* 2171 * Note: we no longer distinguish between VMIO and non-VMIO 2172 * buffers. 2173 */ 2174 KASSERT((bp->b_flags & B_DELWRI) == 0, 2175 ("delwri buffer %p found in queue %d", bp, qindex)); 2176 2177 if (qindex == QUEUE_CLEAN) { 2178 if (bp->b_flags & B_VMIO) { 2179 bp->b_flags &= ~B_ASYNC; 2180 vfs_vmio_release(bp); 2181 } 2182 if (bp->b_vp != NULL) 2183 brelvp(bp); 2184 } 2185 2186 /* 2187 * Get the rest of the buffer freed up. b_kva* is still valid 2188 * after this operation. 2189 */ 2190 2191 if (bp->b_rcred != NOCRED) { 2192 crfree(bp->b_rcred); 2193 bp->b_rcred = NOCRED; 2194 } 2195 if (bp->b_wcred != NOCRED) { 2196 crfree(bp->b_wcred); 2197 bp->b_wcred = NOCRED; 2198 } 2199 if (!LIST_EMPTY(&bp->b_dep)) 2200 buf_deallocate(bp); 2201 if (bp->b_vflags & BV_BKGRDINPROG) 2202 panic("losing buffer 3"); 2203 KASSERT(bp->b_vp == NULL, ("bp: %p still has vnode %p. qindex: %d", 2204 bp, bp->b_vp, qindex)); 2205 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 2206 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags)); 2207 2208 if (bp->b_bufsize) 2209 allocbuf(bp, 0); 2210 2211 bp->b_flags &= B_UNMAPPED | B_KVAALLOC; 2212 bp->b_ioflags = 0; 2213 bp->b_xflags = 0; 2214 KASSERT((bp->b_flags & B_INFREECNT) == 0, 2215 ("buf %p still counted as free?", bp)); 2216 bp->b_vflags = 0; 2217 bp->b_vp = NULL; 2218 bp->b_blkno = bp->b_lblkno = 0; 2219 bp->b_offset = NOOFFSET; 2220 bp->b_iodone = 0; 2221 bp->b_error = 0; 2222 bp->b_resid = 0; 2223 bp->b_bcount = 0; 2224 bp->b_npages = 0; 2225 bp->b_dirtyoff = bp->b_dirtyend = 0; 2226 bp->b_bufobj = NULL; 2227 bp->b_pin_count = 0; 2228 bp->b_fsprivate1 = NULL; 2229 bp->b_fsprivate2 = NULL; 2230 bp->b_fsprivate3 = NULL; 2231 2232 LIST_INIT(&bp->b_dep); 2233 } 2234 2235 static int flushingbufs; 2236 2237 static struct buf * 2238 getnewbuf_scan(int maxsize, int defrag, int unmapped, int metadata) 2239 { 2240 struct buf *bp, *nbp; 2241 int nqindex, qindex, pass; 2242 2243 KASSERT(!unmapped || !defrag, ("both unmapped and defrag")); 2244 2245 pass = 1; 2246 restart: 2247 atomic_add_int(&getnewbufrestarts, 1); 2248 2249 /* 2250 * Setup for scan. If we do not have enough free buffers, 2251 * we setup a degenerate case that immediately fails. Note 2252 * that if we are specially marked process, we are allowed to 2253 * dip into our reserves. 2254 * 2255 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 2256 * for the allocation of the mapped buffer. For unmapped, the 2257 * easiest is to start with EMPTY outright. 2258 * 2259 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 2260 * However, there are a number of cases (defragging, reusing, ...) 2261 * where we cannot backup. 2262 */ 2263 nbp = NULL; 2264 mtx_lock(&bqclean); 2265 if (!defrag && unmapped) { 2266 nqindex = QUEUE_EMPTY; 2267 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 2268 } 2269 if (nbp == NULL) { 2270 nqindex = QUEUE_EMPTYKVA; 2271 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 2272 } 2273 2274 /* 2275 * If no EMPTYKVA buffers and we are either defragging or 2276 * reusing, locate a CLEAN buffer to free or reuse. If 2277 * bufspace useage is low skip this step so we can allocate a 2278 * new buffer. 2279 */ 2280 if (nbp == NULL && (defrag || bufspace >= lobufspace)) { 2281 nqindex = QUEUE_CLEAN; 2282 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2283 } 2284 2285 /* 2286 * If we could not find or were not allowed to reuse a CLEAN 2287 * buffer, check to see if it is ok to use an EMPTY buffer. 2288 * We can only use an EMPTY buffer if allocating its KVA would 2289 * not otherwise run us out of buffer space. No KVA is needed 2290 * for the unmapped allocation. 2291 */ 2292 if (nbp == NULL && defrag == 0 && (bufspace + maxsize < hibufspace || 2293 metadata)) { 2294 nqindex = QUEUE_EMPTY; 2295 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 2296 } 2297 2298 /* 2299 * All available buffers might be clean, retry ignoring the 2300 * lobufspace as the last resort. 2301 */ 2302 if (nbp == NULL && !TAILQ_EMPTY(&bufqueues[QUEUE_CLEAN])) { 2303 nqindex = QUEUE_CLEAN; 2304 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2305 } 2306 2307 /* 2308 * Run scan, possibly freeing data and/or kva mappings on the fly 2309 * depending. 2310 */ 2311 while ((bp = nbp) != NULL) { 2312 qindex = nqindex; 2313 2314 /* 2315 * Calculate next bp (we can only use it if we do not 2316 * block or do other fancy things). 2317 */ 2318 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 2319 switch (qindex) { 2320 case QUEUE_EMPTY: 2321 nqindex = QUEUE_EMPTYKVA; 2322 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 2323 if (nbp != NULL) 2324 break; 2325 /* FALLTHROUGH */ 2326 case QUEUE_EMPTYKVA: 2327 nqindex = QUEUE_CLEAN; 2328 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2329 if (nbp != NULL) 2330 break; 2331 /* FALLTHROUGH */ 2332 case QUEUE_CLEAN: 2333 if (metadata && pass == 1) { 2334 pass = 2; 2335 nqindex = QUEUE_EMPTY; 2336 nbp = TAILQ_FIRST( 2337 &bufqueues[QUEUE_EMPTY]); 2338 } 2339 /* 2340 * nbp is NULL. 2341 */ 2342 break; 2343 } 2344 } 2345 /* 2346 * If we are defragging then we need a buffer with 2347 * b_kvasize != 0. XXX this situation should no longer 2348 * occur, if defrag is non-zero the buffer's b_kvasize 2349 * should also be non-zero at this point. XXX 2350 */ 2351 if (defrag && bp->b_kvasize == 0) { 2352 printf("Warning: defrag empty buffer %p\n", bp); 2353 continue; 2354 } 2355 2356 /* 2357 * Start freeing the bp. This is somewhat involved. nbp 2358 * remains valid only for QUEUE_EMPTY[KVA] bp's. 2359 */ 2360 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2361 continue; 2362 /* 2363 * BKGRDINPROG can only be set with the buf and bufobj 2364 * locks both held. We tolerate a race to clear it here. 2365 */ 2366 if (bp->b_vflags & BV_BKGRDINPROG) { 2367 BUF_UNLOCK(bp); 2368 continue; 2369 } 2370 2371 KASSERT(bp->b_qindex == qindex, 2372 ("getnewbuf: inconsistent queue %d bp %p", qindex, bp)); 2373 2374 bremfreel(bp); 2375 mtx_unlock(&bqclean); 2376 /* 2377 * NOTE: nbp is now entirely invalid. We can only restart 2378 * the scan from this point on. 2379 */ 2380 2381 getnewbuf_reuse_bp(bp, qindex); 2382 mtx_assert(&bqclean, MA_NOTOWNED); 2383 2384 /* 2385 * If we are defragging then free the buffer. 2386 */ 2387 if (defrag) { 2388 bp->b_flags |= B_INVAL; 2389 bfreekva(bp); 2390 brelse(bp); 2391 defrag = 0; 2392 goto restart; 2393 } 2394 2395 /* 2396 * Notify any waiters for the buffer lock about 2397 * identity change by freeing the buffer. 2398 */ 2399 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp)) { 2400 bp->b_flags |= B_INVAL; 2401 bfreekva(bp); 2402 brelse(bp); 2403 goto restart; 2404 } 2405 2406 if (metadata) 2407 break; 2408 2409 /* 2410 * If we are overcomitted then recover the buffer and its 2411 * KVM space. This occurs in rare situations when multiple 2412 * processes are blocked in getnewbuf() or allocbuf(). 2413 */ 2414 if (bufspace >= hibufspace) 2415 flushingbufs = 1; 2416 if (flushingbufs && bp->b_kvasize != 0) { 2417 bp->b_flags |= B_INVAL; 2418 bfreekva(bp); 2419 brelse(bp); 2420 goto restart; 2421 } 2422 if (bufspace < lobufspace) 2423 flushingbufs = 0; 2424 break; 2425 } 2426 return (bp); 2427 } 2428 2429 /* 2430 * getnewbuf: 2431 * 2432 * Find and initialize a new buffer header, freeing up existing buffers 2433 * in the bufqueues as necessary. The new buffer is returned locked. 2434 * 2435 * Important: B_INVAL is not set. If the caller wishes to throw the 2436 * buffer away, the caller must set B_INVAL prior to calling brelse(). 2437 * 2438 * We block if: 2439 * We have insufficient buffer headers 2440 * We have insufficient buffer space 2441 * buffer_arena is too fragmented ( space reservation fails ) 2442 * If we have to flush dirty buffers ( but we try to avoid this ) 2443 */ 2444 static struct buf * 2445 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int size, int maxsize, 2446 int gbflags) 2447 { 2448 struct buf *bp; 2449 int defrag, metadata; 2450 2451 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 2452 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 2453 if (!unmapped_buf_allowed) 2454 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC); 2455 2456 defrag = 0; 2457 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 || 2458 vp->v_type == VCHR) 2459 metadata = 1; 2460 else 2461 metadata = 0; 2462 /* 2463 * We can't afford to block since we might be holding a vnode lock, 2464 * which may prevent system daemons from running. We deal with 2465 * low-memory situations by proactively returning memory and running 2466 * async I/O rather then sync I/O. 2467 */ 2468 atomic_add_int(&getnewbufcalls, 1); 2469 atomic_subtract_int(&getnewbufrestarts, 1); 2470 restart: 2471 bp = getnewbuf_scan(maxsize, defrag, (gbflags & (GB_UNMAPPED | 2472 GB_KVAALLOC)) == GB_UNMAPPED, metadata); 2473 if (bp != NULL) 2474 defrag = 0; 2475 2476 /* 2477 * If we exhausted our list, sleep as appropriate. We may have to 2478 * wakeup various daemons and write out some dirty buffers. 2479 * 2480 * Generally we are sleeping due to insufficient buffer space. 2481 */ 2482 if (bp == NULL) { 2483 mtx_assert(&bqclean, MA_OWNED); 2484 getnewbuf_bufd_help(vp, gbflags, slpflag, slptimeo, defrag); 2485 mtx_assert(&bqclean, MA_NOTOWNED); 2486 } else if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == GB_UNMAPPED) { 2487 mtx_assert(&bqclean, MA_NOTOWNED); 2488 2489 bfreekva(bp); 2490 bp->b_flags |= B_UNMAPPED; 2491 bp->b_kvabase = bp->b_data = unmapped_buf; 2492 bp->b_kvasize = maxsize; 2493 atomic_add_long(&bufspace, bp->b_kvasize); 2494 atomic_add_long(&unmapped_bufspace, bp->b_kvasize); 2495 atomic_add_int(&bufreusecnt, 1); 2496 } else { 2497 mtx_assert(&bqclean, MA_NOTOWNED); 2498 2499 /* 2500 * We finally have a valid bp. We aren't quite out of the 2501 * woods, we still have to reserve kva space. In order 2502 * to keep fragmentation sane we only allocate kva in 2503 * BKVASIZE chunks. 2504 */ 2505 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2506 2507 if (maxsize != bp->b_kvasize || (bp->b_flags & (B_UNMAPPED | 2508 B_KVAALLOC)) == B_UNMAPPED) { 2509 if (allocbufkva(bp, maxsize, gbflags)) { 2510 defrag = 1; 2511 bp->b_flags |= B_INVAL; 2512 brelse(bp); 2513 goto restart; 2514 } 2515 atomic_add_int(&bufreusecnt, 1); 2516 } else if ((bp->b_flags & B_KVAALLOC) != 0 && 2517 (gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == 0) { 2518 /* 2519 * If the reused buffer has KVA allocated, 2520 * reassign b_kvaalloc to b_kvabase. 2521 */ 2522 bp->b_kvabase = bp->b_kvaalloc; 2523 bp->b_flags &= ~B_KVAALLOC; 2524 atomic_subtract_long(&unmapped_bufspace, 2525 bp->b_kvasize); 2526 atomic_add_int(&bufreusecnt, 1); 2527 } else if ((bp->b_flags & (B_UNMAPPED | B_KVAALLOC)) == 0 && 2528 (gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == (GB_UNMAPPED | 2529 GB_KVAALLOC)) { 2530 /* 2531 * The case of reused buffer already have KVA 2532 * mapped, but the request is for unmapped 2533 * buffer with KVA allocated. 2534 */ 2535 bp->b_kvaalloc = bp->b_kvabase; 2536 bp->b_data = bp->b_kvabase = unmapped_buf; 2537 bp->b_flags |= B_UNMAPPED | B_KVAALLOC; 2538 atomic_add_long(&unmapped_bufspace, 2539 bp->b_kvasize); 2540 atomic_add_int(&bufreusecnt, 1); 2541 } 2542 if ((gbflags & GB_UNMAPPED) == 0) { 2543 bp->b_saveaddr = bp->b_kvabase; 2544 bp->b_data = bp->b_saveaddr; 2545 bp->b_flags &= ~B_UNMAPPED; 2546 BUF_CHECK_MAPPED(bp); 2547 } 2548 } 2549 return (bp); 2550 } 2551 2552 /* 2553 * buf_daemon: 2554 * 2555 * buffer flushing daemon. Buffers are normally flushed by the 2556 * update daemon but if it cannot keep up this process starts to 2557 * take the load in an attempt to prevent getnewbuf() from blocking. 2558 */ 2559 2560 static struct kproc_desc buf_kp = { 2561 "bufdaemon", 2562 buf_daemon, 2563 &bufdaemonproc 2564 }; 2565 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 2566 2567 static int 2568 buf_flush(int target) 2569 { 2570 int flushed; 2571 2572 flushed = flushbufqueues(target, 0); 2573 if (flushed == 0) { 2574 /* 2575 * Could not find any buffers without rollback 2576 * dependencies, so just write the first one 2577 * in the hopes of eventually making progress. 2578 */ 2579 flushed = flushbufqueues(target, 1); 2580 } 2581 return (flushed); 2582 } 2583 2584 static void 2585 buf_daemon() 2586 { 2587 int lodirty; 2588 2589 /* 2590 * This process needs to be suspended prior to shutdown sync. 2591 */ 2592 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2593 SHUTDOWN_PRI_LAST); 2594 2595 /* 2596 * This process is allowed to take the buffer cache to the limit 2597 */ 2598 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 2599 mtx_lock(&bdlock); 2600 for (;;) { 2601 bd_request = 0; 2602 mtx_unlock(&bdlock); 2603 2604 kproc_suspend_check(bufdaemonproc); 2605 lodirty = lodirtybuffers; 2606 if (bd_speedupreq) { 2607 lodirty = numdirtybuffers / 2; 2608 bd_speedupreq = 0; 2609 } 2610 /* 2611 * Do the flush. Limit the amount of in-transit I/O we 2612 * allow to build up, otherwise we would completely saturate 2613 * the I/O system. 2614 */ 2615 while (numdirtybuffers > lodirty) { 2616 if (buf_flush(numdirtybuffers - lodirty) == 0) 2617 break; 2618 kern_yield(PRI_USER); 2619 } 2620 2621 /* 2622 * Only clear bd_request if we have reached our low water 2623 * mark. The buf_daemon normally waits 1 second and 2624 * then incrementally flushes any dirty buffers that have 2625 * built up, within reason. 2626 * 2627 * If we were unable to hit our low water mark and couldn't 2628 * find any flushable buffers, we sleep for a short period 2629 * to avoid endless loops on unlockable buffers. 2630 */ 2631 mtx_lock(&bdlock); 2632 if (numdirtybuffers <= lodirtybuffers) { 2633 /* 2634 * We reached our low water mark, reset the 2635 * request and sleep until we are needed again. 2636 * The sleep is just so the suspend code works. 2637 */ 2638 bd_request = 0; 2639 /* 2640 * Do an extra wakeup in case dirty threshold 2641 * changed via sysctl and the explicit transition 2642 * out of shortfall was missed. 2643 */ 2644 bdirtywakeup(); 2645 if (runningbufspace <= lorunningspace) 2646 runningwakeup(); 2647 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 2648 } else { 2649 /* 2650 * We couldn't find any flushable dirty buffers but 2651 * still have too many dirty buffers, we 2652 * have to sleep and try again. (rare) 2653 */ 2654 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 2655 } 2656 } 2657 } 2658 2659 /* 2660 * flushbufqueues: 2661 * 2662 * Try to flush a buffer in the dirty queue. We must be careful to 2663 * free up B_INVAL buffers instead of write them, which NFS is 2664 * particularly sensitive to. 2665 */ 2666 static int flushwithdeps = 0; 2667 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 2668 0, "Number of buffers flushed with dependecies that require rollbacks"); 2669 2670 static int 2671 flushbufqueues(int target, int flushdeps) 2672 { 2673 struct buf *sentinel; 2674 struct vnode *vp; 2675 struct mount *mp; 2676 struct buf *bp; 2677 int hasdeps; 2678 int flushed; 2679 int queue; 2680 int error; 2681 2682 flushed = 0; 2683 queue = QUEUE_DIRTY; 2684 bp = NULL; 2685 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 2686 sentinel->b_qindex = QUEUE_SENTINEL; 2687 mtx_lock(&bqdirty); 2688 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist); 2689 mtx_unlock(&bqdirty); 2690 while (flushed != target) { 2691 maybe_yield(); 2692 mtx_lock(&bqdirty); 2693 bp = TAILQ_NEXT(sentinel, b_freelist); 2694 if (bp != NULL) { 2695 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2696 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel, 2697 b_freelist); 2698 } else { 2699 mtx_unlock(&bqdirty); 2700 break; 2701 } 2702 KASSERT(bp->b_qindex != QUEUE_SENTINEL, 2703 ("parallel calls to flushbufqueues() bp %p", bp)); 2704 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL); 2705 mtx_unlock(&bqdirty); 2706 if (error != 0) 2707 continue; 2708 if (bp->b_pin_count > 0) { 2709 BUF_UNLOCK(bp); 2710 continue; 2711 } 2712 /* 2713 * BKGRDINPROG can only be set with the buf and bufobj 2714 * locks both held. We tolerate a race to clear it here. 2715 */ 2716 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 2717 (bp->b_flags & B_DELWRI) == 0) { 2718 BUF_UNLOCK(bp); 2719 continue; 2720 } 2721 if (bp->b_flags & B_INVAL) { 2722 bremfreef(bp); 2723 brelse(bp); 2724 flushed++; 2725 continue; 2726 } 2727 2728 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 2729 if (flushdeps == 0) { 2730 BUF_UNLOCK(bp); 2731 continue; 2732 } 2733 hasdeps = 1; 2734 } else 2735 hasdeps = 0; 2736 /* 2737 * We must hold the lock on a vnode before writing 2738 * one of its buffers. Otherwise we may confuse, or 2739 * in the case of a snapshot vnode, deadlock the 2740 * system. 2741 * 2742 * The lock order here is the reverse of the normal 2743 * of vnode followed by buf lock. This is ok because 2744 * the NOWAIT will prevent deadlock. 2745 */ 2746 vp = bp->b_vp; 2747 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 2748 BUF_UNLOCK(bp); 2749 continue; 2750 } 2751 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT); 2752 if (error == 0) { 2753 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 2754 bp, bp->b_vp, bp->b_flags); 2755 vfs_bio_awrite(bp); 2756 vn_finished_write(mp); 2757 VOP_UNLOCK(vp, 0); 2758 flushwithdeps += hasdeps; 2759 flushed++; 2760 if (runningbufspace > hirunningspace) 2761 waitrunningbufspace(); 2762 continue; 2763 } 2764 vn_finished_write(mp); 2765 BUF_UNLOCK(bp); 2766 } 2767 mtx_lock(&bqdirty); 2768 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2769 mtx_unlock(&bqdirty); 2770 free(sentinel, M_TEMP); 2771 return (flushed); 2772 } 2773 2774 /* 2775 * Check to see if a block is currently memory resident. 2776 */ 2777 struct buf * 2778 incore(struct bufobj *bo, daddr_t blkno) 2779 { 2780 struct buf *bp; 2781 2782 BO_RLOCK(bo); 2783 bp = gbincore(bo, blkno); 2784 BO_RUNLOCK(bo); 2785 return (bp); 2786 } 2787 2788 /* 2789 * Returns true if no I/O is needed to access the 2790 * associated VM object. This is like incore except 2791 * it also hunts around in the VM system for the data. 2792 */ 2793 2794 static int 2795 inmem(struct vnode * vp, daddr_t blkno) 2796 { 2797 vm_object_t obj; 2798 vm_offset_t toff, tinc, size; 2799 vm_page_t m; 2800 vm_ooffset_t off; 2801 2802 ASSERT_VOP_LOCKED(vp, "inmem"); 2803 2804 if (incore(&vp->v_bufobj, blkno)) 2805 return 1; 2806 if (vp->v_mount == NULL) 2807 return 0; 2808 obj = vp->v_object; 2809 if (obj == NULL) 2810 return (0); 2811 2812 size = PAGE_SIZE; 2813 if (size > vp->v_mount->mnt_stat.f_iosize) 2814 size = vp->v_mount->mnt_stat.f_iosize; 2815 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2816 2817 VM_OBJECT_RLOCK(obj); 2818 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2819 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2820 if (!m) 2821 goto notinmem; 2822 tinc = size; 2823 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2824 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2825 if (vm_page_is_valid(m, 2826 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2827 goto notinmem; 2828 } 2829 VM_OBJECT_RUNLOCK(obj); 2830 return 1; 2831 2832 notinmem: 2833 VM_OBJECT_RUNLOCK(obj); 2834 return (0); 2835 } 2836 2837 /* 2838 * Set the dirty range for a buffer based on the status of the dirty 2839 * bits in the pages comprising the buffer. The range is limited 2840 * to the size of the buffer. 2841 * 2842 * Tell the VM system that the pages associated with this buffer 2843 * are clean. This is used for delayed writes where the data is 2844 * going to go to disk eventually without additional VM intevention. 2845 * 2846 * Note that while we only really need to clean through to b_bcount, we 2847 * just go ahead and clean through to b_bufsize. 2848 */ 2849 static void 2850 vfs_clean_pages_dirty_buf(struct buf *bp) 2851 { 2852 vm_ooffset_t foff, noff, eoff; 2853 vm_page_t m; 2854 int i; 2855 2856 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 2857 return; 2858 2859 foff = bp->b_offset; 2860 KASSERT(bp->b_offset != NOOFFSET, 2861 ("vfs_clean_pages_dirty_buf: no buffer offset")); 2862 2863 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 2864 vfs_drain_busy_pages(bp); 2865 vfs_setdirty_locked_object(bp); 2866 for (i = 0; i < bp->b_npages; i++) { 2867 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2868 eoff = noff; 2869 if (eoff > bp->b_offset + bp->b_bufsize) 2870 eoff = bp->b_offset + bp->b_bufsize; 2871 m = bp->b_pages[i]; 2872 vfs_page_set_validclean(bp, foff, m); 2873 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 2874 foff = noff; 2875 } 2876 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 2877 } 2878 2879 static void 2880 vfs_setdirty_locked_object(struct buf *bp) 2881 { 2882 vm_object_t object; 2883 int i; 2884 2885 object = bp->b_bufobj->bo_object; 2886 VM_OBJECT_ASSERT_WLOCKED(object); 2887 2888 /* 2889 * We qualify the scan for modified pages on whether the 2890 * object has been flushed yet. 2891 */ 2892 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) { 2893 vm_offset_t boffset; 2894 vm_offset_t eoffset; 2895 2896 /* 2897 * test the pages to see if they have been modified directly 2898 * by users through the VM system. 2899 */ 2900 for (i = 0; i < bp->b_npages; i++) 2901 vm_page_test_dirty(bp->b_pages[i]); 2902 2903 /* 2904 * Calculate the encompassing dirty range, boffset and eoffset, 2905 * (eoffset - boffset) bytes. 2906 */ 2907 2908 for (i = 0; i < bp->b_npages; i++) { 2909 if (bp->b_pages[i]->dirty) 2910 break; 2911 } 2912 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2913 2914 for (i = bp->b_npages - 1; i >= 0; --i) { 2915 if (bp->b_pages[i]->dirty) { 2916 break; 2917 } 2918 } 2919 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2920 2921 /* 2922 * Fit it to the buffer. 2923 */ 2924 2925 if (eoffset > bp->b_bcount) 2926 eoffset = bp->b_bcount; 2927 2928 /* 2929 * If we have a good dirty range, merge with the existing 2930 * dirty range. 2931 */ 2932 2933 if (boffset < eoffset) { 2934 if (bp->b_dirtyoff > boffset) 2935 bp->b_dirtyoff = boffset; 2936 if (bp->b_dirtyend < eoffset) 2937 bp->b_dirtyend = eoffset; 2938 } 2939 } 2940 } 2941 2942 /* 2943 * Allocate the KVA mapping for an existing buffer. It handles the 2944 * cases of both B_UNMAPPED buffer, and buffer with the preallocated 2945 * KVA which is not mapped (B_KVAALLOC). 2946 */ 2947 static void 2948 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags) 2949 { 2950 struct buf *scratch_bp; 2951 int bsize, maxsize, need_mapping, need_kva; 2952 off_t offset; 2953 2954 need_mapping = (bp->b_flags & B_UNMAPPED) != 0 && 2955 (gbflags & GB_UNMAPPED) == 0; 2956 need_kva = (bp->b_flags & (B_KVAALLOC | B_UNMAPPED)) == B_UNMAPPED && 2957 (gbflags & GB_KVAALLOC) != 0; 2958 if (!need_mapping && !need_kva) 2959 return; 2960 2961 BUF_CHECK_UNMAPPED(bp); 2962 2963 if (need_mapping && (bp->b_flags & B_KVAALLOC) != 0) { 2964 /* 2965 * Buffer is not mapped, but the KVA was already 2966 * reserved at the time of the instantiation. Use the 2967 * allocated space. 2968 */ 2969 bp->b_flags &= ~B_KVAALLOC; 2970 KASSERT(bp->b_kvaalloc != 0, ("kvaalloc == 0")); 2971 bp->b_kvabase = bp->b_kvaalloc; 2972 atomic_subtract_long(&unmapped_bufspace, bp->b_kvasize); 2973 goto has_addr; 2974 } 2975 2976 /* 2977 * Calculate the amount of the address space we would reserve 2978 * if the buffer was mapped. 2979 */ 2980 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize; 2981 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 2982 offset = blkno * bsize; 2983 maxsize = size + (offset & PAGE_MASK); 2984 maxsize = imax(maxsize, bsize); 2985 2986 mapping_loop: 2987 if (allocbufkva(bp, maxsize, gbflags)) { 2988 /* 2989 * Request defragmentation. getnewbuf() returns us the 2990 * allocated space by the scratch buffer KVA. 2991 */ 2992 scratch_bp = getnewbuf(bp->b_vp, 0, 0, size, maxsize, gbflags | 2993 (GB_UNMAPPED | GB_KVAALLOC)); 2994 if (scratch_bp == NULL) { 2995 if ((gbflags & GB_NOWAIT_BD) != 0) { 2996 /* 2997 * XXXKIB: defragmentation cannot 2998 * succeed, not sure what else to do. 2999 */ 3000 panic("GB_NOWAIT_BD and B_UNMAPPED %p", bp); 3001 } 3002 atomic_add_int(&mappingrestarts, 1); 3003 goto mapping_loop; 3004 } 3005 KASSERT((scratch_bp->b_flags & B_KVAALLOC) != 0, 3006 ("scratch bp !B_KVAALLOC %p", scratch_bp)); 3007 setbufkva(bp, (vm_offset_t)scratch_bp->b_kvaalloc, 3008 scratch_bp->b_kvasize, gbflags); 3009 3010 /* Get rid of the scratch buffer. */ 3011 scratch_bp->b_kvasize = 0; 3012 scratch_bp->b_flags |= B_INVAL; 3013 scratch_bp->b_flags &= ~(B_UNMAPPED | B_KVAALLOC); 3014 brelse(scratch_bp); 3015 } 3016 if (!need_mapping) 3017 return; 3018 3019 has_addr: 3020 bp->b_saveaddr = bp->b_kvabase; 3021 bp->b_data = bp->b_saveaddr; /* b_offset is handled by bpmap_qenter */ 3022 bp->b_flags &= ~B_UNMAPPED; 3023 BUF_CHECK_MAPPED(bp); 3024 bpmap_qenter(bp); 3025 } 3026 3027 /* 3028 * getblk: 3029 * 3030 * Get a block given a specified block and offset into a file/device. 3031 * The buffers B_DONE bit will be cleared on return, making it almost 3032 * ready for an I/O initiation. B_INVAL may or may not be set on 3033 * return. The caller should clear B_INVAL prior to initiating a 3034 * READ. 3035 * 3036 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 3037 * an existing buffer. 3038 * 3039 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 3040 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 3041 * and then cleared based on the backing VM. If the previous buffer is 3042 * non-0-sized but invalid, B_CACHE will be cleared. 3043 * 3044 * If getblk() must create a new buffer, the new buffer is returned with 3045 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 3046 * case it is returned with B_INVAL clear and B_CACHE set based on the 3047 * backing VM. 3048 * 3049 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 3050 * B_CACHE bit is clear. 3051 * 3052 * What this means, basically, is that the caller should use B_CACHE to 3053 * determine whether the buffer is fully valid or not and should clear 3054 * B_INVAL prior to issuing a read. If the caller intends to validate 3055 * the buffer by loading its data area with something, the caller needs 3056 * to clear B_INVAL. If the caller does this without issuing an I/O, 3057 * the caller should set B_CACHE ( as an optimization ), else the caller 3058 * should issue the I/O and biodone() will set B_CACHE if the I/O was 3059 * a write attempt or if it was a successfull read. If the caller 3060 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 3061 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 3062 */ 3063 struct buf * 3064 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3065 int flags) 3066 { 3067 struct buf *bp; 3068 struct bufobj *bo; 3069 int bsize, error, maxsize, vmio; 3070 off_t offset; 3071 3072 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 3073 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3074 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3075 ASSERT_VOP_LOCKED(vp, "getblk"); 3076 if (size > MAXBSIZE) 3077 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 3078 if (!unmapped_buf_allowed) 3079 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3080 3081 bo = &vp->v_bufobj; 3082 loop: 3083 BO_RLOCK(bo); 3084 bp = gbincore(bo, blkno); 3085 if (bp != NULL) { 3086 int lockflags; 3087 /* 3088 * Buffer is in-core. If the buffer is not busy nor managed, 3089 * it must be on a queue. 3090 */ 3091 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 3092 3093 if (flags & GB_LOCK_NOWAIT) 3094 lockflags |= LK_NOWAIT; 3095 3096 error = BUF_TIMELOCK(bp, lockflags, 3097 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo); 3098 3099 /* 3100 * If we slept and got the lock we have to restart in case 3101 * the buffer changed identities. 3102 */ 3103 if (error == ENOLCK) 3104 goto loop; 3105 /* We timed out or were interrupted. */ 3106 else if (error) 3107 return (NULL); 3108 /* If recursed, assume caller knows the rules. */ 3109 else if (BUF_LOCKRECURSED(bp)) 3110 goto end; 3111 3112 /* 3113 * The buffer is locked. B_CACHE is cleared if the buffer is 3114 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 3115 * and for a VMIO buffer B_CACHE is adjusted according to the 3116 * backing VM cache. 3117 */ 3118 if (bp->b_flags & B_INVAL) 3119 bp->b_flags &= ~B_CACHE; 3120 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 3121 bp->b_flags |= B_CACHE; 3122 if (bp->b_flags & B_MANAGED) 3123 MPASS(bp->b_qindex == QUEUE_NONE); 3124 else 3125 bremfree(bp); 3126 3127 /* 3128 * check for size inconsistencies for non-VMIO case. 3129 */ 3130 if (bp->b_bcount != size) { 3131 if ((bp->b_flags & B_VMIO) == 0 || 3132 (size > bp->b_kvasize)) { 3133 if (bp->b_flags & B_DELWRI) { 3134 /* 3135 * If buffer is pinned and caller does 3136 * not want sleep waiting for it to be 3137 * unpinned, bail out 3138 * */ 3139 if (bp->b_pin_count > 0) { 3140 if (flags & GB_LOCK_NOWAIT) { 3141 bqrelse(bp); 3142 return (NULL); 3143 } else { 3144 bunpin_wait(bp); 3145 } 3146 } 3147 bp->b_flags |= B_NOCACHE; 3148 bwrite(bp); 3149 } else { 3150 if (LIST_EMPTY(&bp->b_dep)) { 3151 bp->b_flags |= B_RELBUF; 3152 brelse(bp); 3153 } else { 3154 bp->b_flags |= B_NOCACHE; 3155 bwrite(bp); 3156 } 3157 } 3158 goto loop; 3159 } 3160 } 3161 3162 /* 3163 * Handle the case of unmapped buffer which should 3164 * become mapped, or the buffer for which KVA 3165 * reservation is requested. 3166 */ 3167 bp_unmapped_get_kva(bp, blkno, size, flags); 3168 3169 /* 3170 * If the size is inconsistant in the VMIO case, we can resize 3171 * the buffer. This might lead to B_CACHE getting set or 3172 * cleared. If the size has not changed, B_CACHE remains 3173 * unchanged from its previous state. 3174 */ 3175 if (bp->b_bcount != size) 3176 allocbuf(bp, size); 3177 3178 KASSERT(bp->b_offset != NOOFFSET, 3179 ("getblk: no buffer offset")); 3180 3181 /* 3182 * A buffer with B_DELWRI set and B_CACHE clear must 3183 * be committed before we can return the buffer in 3184 * order to prevent the caller from issuing a read 3185 * ( due to B_CACHE not being set ) and overwriting 3186 * it. 3187 * 3188 * Most callers, including NFS and FFS, need this to 3189 * operate properly either because they assume they 3190 * can issue a read if B_CACHE is not set, or because 3191 * ( for example ) an uncached B_DELWRI might loop due 3192 * to softupdates re-dirtying the buffer. In the latter 3193 * case, B_CACHE is set after the first write completes, 3194 * preventing further loops. 3195 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 3196 * above while extending the buffer, we cannot allow the 3197 * buffer to remain with B_CACHE set after the write 3198 * completes or it will represent a corrupt state. To 3199 * deal with this we set B_NOCACHE to scrap the buffer 3200 * after the write. 3201 * 3202 * We might be able to do something fancy, like setting 3203 * B_CACHE in bwrite() except if B_DELWRI is already set, 3204 * so the below call doesn't set B_CACHE, but that gets real 3205 * confusing. This is much easier. 3206 */ 3207 3208 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 3209 bp->b_flags |= B_NOCACHE; 3210 bwrite(bp); 3211 goto loop; 3212 } 3213 bp->b_flags &= ~B_DONE; 3214 } else { 3215 /* 3216 * Buffer is not in-core, create new buffer. The buffer 3217 * returned by getnewbuf() is locked. Note that the returned 3218 * buffer is also considered valid (not marked B_INVAL). 3219 */ 3220 BO_RUNLOCK(bo); 3221 /* 3222 * If the user does not want us to create the buffer, bail out 3223 * here. 3224 */ 3225 if (flags & GB_NOCREAT) 3226 return NULL; 3227 if (numfreebuffers == 0 && TD_IS_IDLETHREAD(curthread)) 3228 return NULL; 3229 3230 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize; 3231 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3232 offset = blkno * bsize; 3233 vmio = vp->v_object != NULL; 3234 if (vmio) { 3235 maxsize = size + (offset & PAGE_MASK); 3236 } else { 3237 maxsize = size; 3238 /* Do not allow non-VMIO notmapped buffers. */ 3239 flags &= ~GB_UNMAPPED; 3240 } 3241 maxsize = imax(maxsize, bsize); 3242 3243 bp = getnewbuf(vp, slpflag, slptimeo, size, maxsize, flags); 3244 if (bp == NULL) { 3245 if (slpflag || slptimeo) 3246 return NULL; 3247 goto loop; 3248 } 3249 3250 /* 3251 * This code is used to make sure that a buffer is not 3252 * created while the getnewbuf routine is blocked. 3253 * This can be a problem whether the vnode is locked or not. 3254 * If the buffer is created out from under us, we have to 3255 * throw away the one we just created. 3256 * 3257 * Note: this must occur before we associate the buffer 3258 * with the vp especially considering limitations in 3259 * the splay tree implementation when dealing with duplicate 3260 * lblkno's. 3261 */ 3262 BO_LOCK(bo); 3263 if (gbincore(bo, blkno)) { 3264 BO_UNLOCK(bo); 3265 bp->b_flags |= B_INVAL; 3266 brelse(bp); 3267 goto loop; 3268 } 3269 3270 /* 3271 * Insert the buffer into the hash, so that it can 3272 * be found by incore. 3273 */ 3274 bp->b_blkno = bp->b_lblkno = blkno; 3275 bp->b_offset = offset; 3276 bgetvp(vp, bp); 3277 BO_UNLOCK(bo); 3278 3279 /* 3280 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 3281 * buffer size starts out as 0, B_CACHE will be set by 3282 * allocbuf() for the VMIO case prior to it testing the 3283 * backing store for validity. 3284 */ 3285 3286 if (vmio) { 3287 bp->b_flags |= B_VMIO; 3288 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 3289 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 3290 bp, vp->v_object, bp->b_bufobj->bo_object)); 3291 } else { 3292 bp->b_flags &= ~B_VMIO; 3293 KASSERT(bp->b_bufobj->bo_object == NULL, 3294 ("ARGH! has b_bufobj->bo_object %p %p\n", 3295 bp, bp->b_bufobj->bo_object)); 3296 BUF_CHECK_MAPPED(bp); 3297 } 3298 3299 allocbuf(bp, size); 3300 bp->b_flags &= ~B_DONE; 3301 } 3302 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 3303 BUF_ASSERT_HELD(bp); 3304 end: 3305 KASSERT(bp->b_bufobj == bo, 3306 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 3307 return (bp); 3308 } 3309 3310 /* 3311 * Get an empty, disassociated buffer of given size. The buffer is initially 3312 * set to B_INVAL. 3313 */ 3314 struct buf * 3315 geteblk(int size, int flags) 3316 { 3317 struct buf *bp; 3318 int maxsize; 3319 3320 maxsize = (size + BKVAMASK) & ~BKVAMASK; 3321 while ((bp = getnewbuf(NULL, 0, 0, size, maxsize, flags)) == NULL) { 3322 if ((flags & GB_NOWAIT_BD) && 3323 (curthread->td_pflags & TDP_BUFNEED) != 0) 3324 return (NULL); 3325 } 3326 allocbuf(bp, size); 3327 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 3328 BUF_ASSERT_HELD(bp); 3329 return (bp); 3330 } 3331 3332 3333 /* 3334 * This code constitutes the buffer memory from either anonymous system 3335 * memory (in the case of non-VMIO operations) or from an associated 3336 * VM object (in the case of VMIO operations). This code is able to 3337 * resize a buffer up or down. 3338 * 3339 * Note that this code is tricky, and has many complications to resolve 3340 * deadlock or inconsistant data situations. Tread lightly!!! 3341 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 3342 * the caller. Calling this code willy nilly can result in the loss of data. 3343 * 3344 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 3345 * B_CACHE for the non-VMIO case. 3346 */ 3347 3348 int 3349 allocbuf(struct buf *bp, int size) 3350 { 3351 int newbsize, mbsize; 3352 int i; 3353 3354 BUF_ASSERT_HELD(bp); 3355 3356 if (bp->b_kvasize < size) 3357 panic("allocbuf: buffer too small"); 3358 3359 if ((bp->b_flags & B_VMIO) == 0) { 3360 caddr_t origbuf; 3361 int origbufsize; 3362 /* 3363 * Just get anonymous memory from the kernel. Don't 3364 * mess with B_CACHE. 3365 */ 3366 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3367 if (bp->b_flags & B_MALLOC) 3368 newbsize = mbsize; 3369 else 3370 newbsize = round_page(size); 3371 3372 if (newbsize < bp->b_bufsize) { 3373 /* 3374 * malloced buffers are not shrunk 3375 */ 3376 if (bp->b_flags & B_MALLOC) { 3377 if (newbsize) { 3378 bp->b_bcount = size; 3379 } else { 3380 free(bp->b_data, M_BIOBUF); 3381 if (bp->b_bufsize) { 3382 atomic_subtract_long( 3383 &bufmallocspace, 3384 bp->b_bufsize); 3385 bufspacewakeup(); 3386 bp->b_bufsize = 0; 3387 } 3388 bp->b_saveaddr = bp->b_kvabase; 3389 bp->b_data = bp->b_saveaddr; 3390 bp->b_bcount = 0; 3391 bp->b_flags &= ~B_MALLOC; 3392 } 3393 return 1; 3394 } 3395 vm_hold_free_pages(bp, newbsize); 3396 } else if (newbsize > bp->b_bufsize) { 3397 /* 3398 * We only use malloced memory on the first allocation. 3399 * and revert to page-allocated memory when the buffer 3400 * grows. 3401 */ 3402 /* 3403 * There is a potential smp race here that could lead 3404 * to bufmallocspace slightly passing the max. It 3405 * is probably extremely rare and not worth worrying 3406 * over. 3407 */ 3408 if ( (bufmallocspace < maxbufmallocspace) && 3409 (bp->b_bufsize == 0) && 3410 (mbsize <= PAGE_SIZE/2)) { 3411 3412 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 3413 bp->b_bufsize = mbsize; 3414 bp->b_bcount = size; 3415 bp->b_flags |= B_MALLOC; 3416 atomic_add_long(&bufmallocspace, mbsize); 3417 return 1; 3418 } 3419 origbuf = NULL; 3420 origbufsize = 0; 3421 /* 3422 * If the buffer is growing on its other-than-first allocation, 3423 * then we revert to the page-allocation scheme. 3424 */ 3425 if (bp->b_flags & B_MALLOC) { 3426 origbuf = bp->b_data; 3427 origbufsize = bp->b_bufsize; 3428 bp->b_data = bp->b_kvabase; 3429 if (bp->b_bufsize) { 3430 atomic_subtract_long(&bufmallocspace, 3431 bp->b_bufsize); 3432 bufspacewakeup(); 3433 bp->b_bufsize = 0; 3434 } 3435 bp->b_flags &= ~B_MALLOC; 3436 newbsize = round_page(newbsize); 3437 } 3438 vm_hold_load_pages( 3439 bp, 3440 (vm_offset_t) bp->b_data + bp->b_bufsize, 3441 (vm_offset_t) bp->b_data + newbsize); 3442 if (origbuf) { 3443 bcopy(origbuf, bp->b_data, origbufsize); 3444 free(origbuf, M_BIOBUF); 3445 } 3446 } 3447 } else { 3448 int desiredpages; 3449 3450 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3451 desiredpages = (size == 0) ? 0 : 3452 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 3453 3454 if (bp->b_flags & B_MALLOC) 3455 panic("allocbuf: VMIO buffer can't be malloced"); 3456 /* 3457 * Set B_CACHE initially if buffer is 0 length or will become 3458 * 0-length. 3459 */ 3460 if (size == 0 || bp->b_bufsize == 0) 3461 bp->b_flags |= B_CACHE; 3462 3463 if (newbsize < bp->b_bufsize) { 3464 /* 3465 * DEV_BSIZE aligned new buffer size is less then the 3466 * DEV_BSIZE aligned existing buffer size. Figure out 3467 * if we have to remove any pages. 3468 */ 3469 if (desiredpages < bp->b_npages) { 3470 vm_page_t m; 3471 3472 if ((bp->b_flags & B_UNMAPPED) == 0) { 3473 BUF_CHECK_MAPPED(bp); 3474 pmap_qremove((vm_offset_t)trunc_page( 3475 (vm_offset_t)bp->b_data) + 3476 (desiredpages << PAGE_SHIFT), 3477 (bp->b_npages - desiredpages)); 3478 } else 3479 BUF_CHECK_UNMAPPED(bp); 3480 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 3481 for (i = desiredpages; i < bp->b_npages; i++) { 3482 /* 3483 * the page is not freed here -- it 3484 * is the responsibility of 3485 * vnode_pager_setsize 3486 */ 3487 m = bp->b_pages[i]; 3488 KASSERT(m != bogus_page, 3489 ("allocbuf: bogus page found")); 3490 while (vm_page_sleep_if_busy(m, 3491 "biodep")) 3492 continue; 3493 3494 bp->b_pages[i] = NULL; 3495 vm_page_lock(m); 3496 vm_page_unwire(m, PQ_INACTIVE); 3497 vm_page_unlock(m); 3498 } 3499 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 3500 bp->b_npages = desiredpages; 3501 } 3502 } else if (size > bp->b_bcount) { 3503 /* 3504 * We are growing the buffer, possibly in a 3505 * byte-granular fashion. 3506 */ 3507 vm_object_t obj; 3508 vm_offset_t toff; 3509 vm_offset_t tinc; 3510 3511 /* 3512 * Step 1, bring in the VM pages from the object, 3513 * allocating them if necessary. We must clear 3514 * B_CACHE if these pages are not valid for the 3515 * range covered by the buffer. 3516 */ 3517 3518 obj = bp->b_bufobj->bo_object; 3519 3520 VM_OBJECT_WLOCK(obj); 3521 while (bp->b_npages < desiredpages) { 3522 vm_page_t m; 3523 3524 /* 3525 * We must allocate system pages since blocking 3526 * here could interfere with paging I/O, no 3527 * matter which process we are. 3528 * 3529 * Only exclusive busy can be tested here. 3530 * Blocking on shared busy might lead to 3531 * deadlocks once allocbuf() is called after 3532 * pages are vfs_busy_pages(). 3533 */ 3534 m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) + 3535 bp->b_npages, VM_ALLOC_NOBUSY | 3536 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED | 3537 VM_ALLOC_IGN_SBUSY | 3538 VM_ALLOC_COUNT(desiredpages - bp->b_npages)); 3539 if (m->valid == 0) 3540 bp->b_flags &= ~B_CACHE; 3541 bp->b_pages[bp->b_npages] = m; 3542 ++bp->b_npages; 3543 } 3544 3545 /* 3546 * Step 2. We've loaded the pages into the buffer, 3547 * we have to figure out if we can still have B_CACHE 3548 * set. Note that B_CACHE is set according to the 3549 * byte-granular range ( bcount and size ), new the 3550 * aligned range ( newbsize ). 3551 * 3552 * The VM test is against m->valid, which is DEV_BSIZE 3553 * aligned. Needless to say, the validity of the data 3554 * needs to also be DEV_BSIZE aligned. Note that this 3555 * fails with NFS if the server or some other client 3556 * extends the file's EOF. If our buffer is resized, 3557 * B_CACHE may remain set! XXX 3558 */ 3559 3560 toff = bp->b_bcount; 3561 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 3562 3563 while ((bp->b_flags & B_CACHE) && toff < size) { 3564 vm_pindex_t pi; 3565 3566 if (tinc > (size - toff)) 3567 tinc = size - toff; 3568 3569 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 3570 PAGE_SHIFT; 3571 3572 vfs_buf_test_cache( 3573 bp, 3574 bp->b_offset, 3575 toff, 3576 tinc, 3577 bp->b_pages[pi] 3578 ); 3579 toff += tinc; 3580 tinc = PAGE_SIZE; 3581 } 3582 VM_OBJECT_WUNLOCK(obj); 3583 3584 /* 3585 * Step 3, fixup the KVM pmap. 3586 */ 3587 if ((bp->b_flags & B_UNMAPPED) == 0) 3588 bpmap_qenter(bp); 3589 else 3590 BUF_CHECK_UNMAPPED(bp); 3591 } 3592 } 3593 if (newbsize < bp->b_bufsize) 3594 bufspacewakeup(); 3595 bp->b_bufsize = newbsize; /* actual buffer allocation */ 3596 bp->b_bcount = size; /* requested buffer size */ 3597 return 1; 3598 } 3599 3600 extern int inflight_transient_maps; 3601 3602 void 3603 biodone(struct bio *bp) 3604 { 3605 struct mtx *mtxp; 3606 void (*done)(struct bio *); 3607 vm_offset_t start, end; 3608 3609 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) { 3610 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING; 3611 bp->bio_flags |= BIO_UNMAPPED; 3612 start = trunc_page((vm_offset_t)bp->bio_data); 3613 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length); 3614 pmap_qremove(start, OFF_TO_IDX(end - start)); 3615 vmem_free(transient_arena, start, end - start); 3616 atomic_add_int(&inflight_transient_maps, -1); 3617 } 3618 done = bp->bio_done; 3619 if (done == NULL) { 3620 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3621 mtx_lock(mtxp); 3622 bp->bio_flags |= BIO_DONE; 3623 wakeup(bp); 3624 mtx_unlock(mtxp); 3625 } else { 3626 bp->bio_flags |= BIO_DONE; 3627 done(bp); 3628 } 3629 } 3630 3631 /* 3632 * Wait for a BIO to finish. 3633 */ 3634 int 3635 biowait(struct bio *bp, const char *wchan) 3636 { 3637 struct mtx *mtxp; 3638 3639 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3640 mtx_lock(mtxp); 3641 while ((bp->bio_flags & BIO_DONE) == 0) 3642 msleep(bp, mtxp, PRIBIO, wchan, 0); 3643 mtx_unlock(mtxp); 3644 if (bp->bio_error != 0) 3645 return (bp->bio_error); 3646 if (!(bp->bio_flags & BIO_ERROR)) 3647 return (0); 3648 return (EIO); 3649 } 3650 3651 void 3652 biofinish(struct bio *bp, struct devstat *stat, int error) 3653 { 3654 3655 if (error) { 3656 bp->bio_error = error; 3657 bp->bio_flags |= BIO_ERROR; 3658 } 3659 if (stat != NULL) 3660 devstat_end_transaction_bio(stat, bp); 3661 biodone(bp); 3662 } 3663 3664 /* 3665 * bufwait: 3666 * 3667 * Wait for buffer I/O completion, returning error status. The buffer 3668 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3669 * error and cleared. 3670 */ 3671 int 3672 bufwait(struct buf *bp) 3673 { 3674 if (bp->b_iocmd == BIO_READ) 3675 bwait(bp, PRIBIO, "biord"); 3676 else 3677 bwait(bp, PRIBIO, "biowr"); 3678 if (bp->b_flags & B_EINTR) { 3679 bp->b_flags &= ~B_EINTR; 3680 return (EINTR); 3681 } 3682 if (bp->b_ioflags & BIO_ERROR) { 3683 return (bp->b_error ? bp->b_error : EIO); 3684 } else { 3685 return (0); 3686 } 3687 } 3688 3689 /* 3690 * Call back function from struct bio back up to struct buf. 3691 */ 3692 static void 3693 bufdonebio(struct bio *bip) 3694 { 3695 struct buf *bp; 3696 3697 bp = bip->bio_caller2; 3698 bp->b_resid = bip->bio_resid; 3699 bp->b_ioflags = bip->bio_flags; 3700 bp->b_error = bip->bio_error; 3701 if (bp->b_error) 3702 bp->b_ioflags |= BIO_ERROR; 3703 bufdone(bp); 3704 g_destroy_bio(bip); 3705 } 3706 3707 void 3708 dev_strategy(struct cdev *dev, struct buf *bp) 3709 { 3710 struct cdevsw *csw; 3711 int ref; 3712 3713 KASSERT(dev->si_refcount > 0, 3714 ("dev_strategy on un-referenced struct cdev *(%s) %p", 3715 devtoname(dev), dev)); 3716 3717 csw = dev_refthread(dev, &ref); 3718 dev_strategy_csw(dev, csw, bp); 3719 dev_relthread(dev, ref); 3720 } 3721 3722 void 3723 dev_strategy_csw(struct cdev *dev, struct cdevsw *csw, struct buf *bp) 3724 { 3725 struct bio *bip; 3726 3727 KASSERT(bp->b_iocmd == BIO_READ || bp->b_iocmd == BIO_WRITE, 3728 ("b_iocmd botch")); 3729 KASSERT(((dev->si_flags & SI_ETERNAL) != 0 && csw != NULL) || 3730 dev->si_threadcount > 0, 3731 ("dev_strategy_csw threadcount cdev *(%s) %p", devtoname(dev), 3732 dev)); 3733 if (csw == NULL) { 3734 bp->b_error = ENXIO; 3735 bp->b_ioflags = BIO_ERROR; 3736 bufdone(bp); 3737 return; 3738 } 3739 for (;;) { 3740 bip = g_new_bio(); 3741 if (bip != NULL) 3742 break; 3743 /* Try again later */ 3744 tsleep(&bp, PRIBIO, "dev_strat", hz/10); 3745 } 3746 bip->bio_cmd = bp->b_iocmd; 3747 bip->bio_offset = bp->b_iooffset; 3748 bip->bio_length = bp->b_bcount; 3749 bip->bio_bcount = bp->b_bcount; /* XXX: remove */ 3750 bdata2bio(bp, bip); 3751 bip->bio_done = bufdonebio; 3752 bip->bio_caller2 = bp; 3753 bip->bio_dev = dev; 3754 (*csw->d_strategy)(bip); 3755 } 3756 3757 /* 3758 * bufdone: 3759 * 3760 * Finish I/O on a buffer, optionally calling a completion function. 3761 * This is usually called from an interrupt so process blocking is 3762 * not allowed. 3763 * 3764 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3765 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3766 * assuming B_INVAL is clear. 3767 * 3768 * For the VMIO case, we set B_CACHE if the op was a read and no 3769 * read error occured, or if the op was a write. B_CACHE is never 3770 * set if the buffer is invalid or otherwise uncacheable. 3771 * 3772 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3773 * initiator to leave B_INVAL set to brelse the buffer out of existance 3774 * in the biodone routine. 3775 */ 3776 void 3777 bufdone(struct buf *bp) 3778 { 3779 struct bufobj *dropobj; 3780 void (*biodone)(struct buf *); 3781 3782 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 3783 dropobj = NULL; 3784 3785 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 3786 BUF_ASSERT_HELD(bp); 3787 3788 runningbufwakeup(bp); 3789 if (bp->b_iocmd == BIO_WRITE) 3790 dropobj = bp->b_bufobj; 3791 /* call optional completion function if requested */ 3792 if (bp->b_iodone != NULL) { 3793 biodone = bp->b_iodone; 3794 bp->b_iodone = NULL; 3795 (*biodone) (bp); 3796 if (dropobj) 3797 bufobj_wdrop(dropobj); 3798 return; 3799 } 3800 3801 bufdone_finish(bp); 3802 3803 if (dropobj) 3804 bufobj_wdrop(dropobj); 3805 } 3806 3807 void 3808 bufdone_finish(struct buf *bp) 3809 { 3810 BUF_ASSERT_HELD(bp); 3811 3812 if (!LIST_EMPTY(&bp->b_dep)) 3813 buf_complete(bp); 3814 3815 if (bp->b_flags & B_VMIO) { 3816 vm_ooffset_t foff; 3817 vm_page_t m; 3818 vm_object_t obj; 3819 struct vnode *vp; 3820 int bogus, i, iosize; 3821 3822 obj = bp->b_bufobj->bo_object; 3823 KASSERT(obj->paging_in_progress >= bp->b_npages, 3824 ("biodone_finish: paging in progress(%d) < b_npages(%d)", 3825 obj->paging_in_progress, bp->b_npages)); 3826 3827 vp = bp->b_vp; 3828 KASSERT(vp->v_holdcnt > 0, 3829 ("biodone_finish: vnode %p has zero hold count", vp)); 3830 KASSERT(vp->v_object != NULL, 3831 ("biodone_finish: vnode %p has no vm_object", vp)); 3832 3833 foff = bp->b_offset; 3834 KASSERT(bp->b_offset != NOOFFSET, 3835 ("biodone_finish: bp %p has no buffer offset", bp)); 3836 3837 /* 3838 * Set B_CACHE if the op was a normal read and no error 3839 * occured. B_CACHE is set for writes in the b*write() 3840 * routines. 3841 */ 3842 iosize = bp->b_bcount - bp->b_resid; 3843 if (bp->b_iocmd == BIO_READ && 3844 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 3845 !(bp->b_ioflags & BIO_ERROR)) { 3846 bp->b_flags |= B_CACHE; 3847 } 3848 bogus = 0; 3849 VM_OBJECT_WLOCK(obj); 3850 for (i = 0; i < bp->b_npages; i++) { 3851 int bogusflag = 0; 3852 int resid; 3853 3854 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 3855 if (resid > iosize) 3856 resid = iosize; 3857 3858 /* 3859 * cleanup bogus pages, restoring the originals 3860 */ 3861 m = bp->b_pages[i]; 3862 if (m == bogus_page) { 3863 bogus = bogusflag = 1; 3864 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3865 if (m == NULL) 3866 panic("biodone: page disappeared!"); 3867 bp->b_pages[i] = m; 3868 } 3869 KASSERT(OFF_TO_IDX(foff) == m->pindex, 3870 ("biodone_finish: foff(%jd)/pindex(%ju) mismatch", 3871 (intmax_t)foff, (uintmax_t)m->pindex)); 3872 3873 /* 3874 * In the write case, the valid and clean bits are 3875 * already changed correctly ( see bdwrite() ), so we 3876 * only need to do this here in the read case. 3877 */ 3878 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 3879 KASSERT((m->dirty & vm_page_bits(foff & 3880 PAGE_MASK, resid)) == 0, ("bufdone_finish:" 3881 " page %p has unexpected dirty bits", m)); 3882 vfs_page_set_valid(bp, foff, m); 3883 } 3884 3885 vm_page_sunbusy(m); 3886 vm_object_pip_subtract(obj, 1); 3887 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3888 iosize -= resid; 3889 } 3890 vm_object_pip_wakeupn(obj, 0); 3891 VM_OBJECT_WUNLOCK(obj); 3892 if (bogus && (bp->b_flags & B_UNMAPPED) == 0) { 3893 BUF_CHECK_MAPPED(bp); 3894 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3895 bp->b_pages, bp->b_npages); 3896 } 3897 } 3898 3899 /* 3900 * For asynchronous completions, release the buffer now. The brelse 3901 * will do a wakeup there if necessary - so no need to do a wakeup 3902 * here in the async case. The sync case always needs to do a wakeup. 3903 */ 3904 3905 if (bp->b_flags & B_ASYNC) { 3906 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 3907 brelse(bp); 3908 else 3909 bqrelse(bp); 3910 } else 3911 bdone(bp); 3912 } 3913 3914 /* 3915 * This routine is called in lieu of iodone in the case of 3916 * incomplete I/O. This keeps the busy status for pages 3917 * consistant. 3918 */ 3919 void 3920 vfs_unbusy_pages(struct buf *bp) 3921 { 3922 int i; 3923 vm_object_t obj; 3924 vm_page_t m; 3925 3926 runningbufwakeup(bp); 3927 if (!(bp->b_flags & B_VMIO)) 3928 return; 3929 3930 obj = bp->b_bufobj->bo_object; 3931 VM_OBJECT_WLOCK(obj); 3932 for (i = 0; i < bp->b_npages; i++) { 3933 m = bp->b_pages[i]; 3934 if (m == bogus_page) { 3935 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 3936 if (!m) 3937 panic("vfs_unbusy_pages: page missing\n"); 3938 bp->b_pages[i] = m; 3939 if ((bp->b_flags & B_UNMAPPED) == 0) { 3940 BUF_CHECK_MAPPED(bp); 3941 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3942 bp->b_pages, bp->b_npages); 3943 } else 3944 BUF_CHECK_UNMAPPED(bp); 3945 } 3946 vm_object_pip_subtract(obj, 1); 3947 vm_page_sunbusy(m); 3948 } 3949 vm_object_pip_wakeupn(obj, 0); 3950 VM_OBJECT_WUNLOCK(obj); 3951 } 3952 3953 /* 3954 * vfs_page_set_valid: 3955 * 3956 * Set the valid bits in a page based on the supplied offset. The 3957 * range is restricted to the buffer's size. 3958 * 3959 * This routine is typically called after a read completes. 3960 */ 3961 static void 3962 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3963 { 3964 vm_ooffset_t eoff; 3965 3966 /* 3967 * Compute the end offset, eoff, such that [off, eoff) does not span a 3968 * page boundary and eoff is not greater than the end of the buffer. 3969 * The end of the buffer, in this case, is our file EOF, not the 3970 * allocation size of the buffer. 3971 */ 3972 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 3973 if (eoff > bp->b_offset + bp->b_bcount) 3974 eoff = bp->b_offset + bp->b_bcount; 3975 3976 /* 3977 * Set valid range. This is typically the entire buffer and thus the 3978 * entire page. 3979 */ 3980 if (eoff > off) 3981 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off); 3982 } 3983 3984 /* 3985 * vfs_page_set_validclean: 3986 * 3987 * Set the valid bits and clear the dirty bits in a page based on the 3988 * supplied offset. The range is restricted to the buffer's size. 3989 */ 3990 static void 3991 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3992 { 3993 vm_ooffset_t soff, eoff; 3994 3995 /* 3996 * Start and end offsets in buffer. eoff - soff may not cross a 3997 * page boundry or cross the end of the buffer. The end of the 3998 * buffer, in this case, is our file EOF, not the allocation size 3999 * of the buffer. 4000 */ 4001 soff = off; 4002 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4003 if (eoff > bp->b_offset + bp->b_bcount) 4004 eoff = bp->b_offset + bp->b_bcount; 4005 4006 /* 4007 * Set valid range. This is typically the entire buffer and thus the 4008 * entire page. 4009 */ 4010 if (eoff > soff) { 4011 vm_page_set_validclean( 4012 m, 4013 (vm_offset_t) (soff & PAGE_MASK), 4014 (vm_offset_t) (eoff - soff) 4015 ); 4016 } 4017 } 4018 4019 /* 4020 * Ensure that all buffer pages are not exclusive busied. If any page is 4021 * exclusive busy, drain it. 4022 */ 4023 void 4024 vfs_drain_busy_pages(struct buf *bp) 4025 { 4026 vm_page_t m; 4027 int i, last_busied; 4028 4029 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object); 4030 last_busied = 0; 4031 for (i = 0; i < bp->b_npages; i++) { 4032 m = bp->b_pages[i]; 4033 if (vm_page_xbusied(m)) { 4034 for (; last_busied < i; last_busied++) 4035 vm_page_sbusy(bp->b_pages[last_busied]); 4036 while (vm_page_xbusied(m)) { 4037 vm_page_lock(m); 4038 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4039 vm_page_busy_sleep(m, "vbpage"); 4040 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4041 } 4042 } 4043 } 4044 for (i = 0; i < last_busied; i++) 4045 vm_page_sunbusy(bp->b_pages[i]); 4046 } 4047 4048 /* 4049 * This routine is called before a device strategy routine. 4050 * It is used to tell the VM system that paging I/O is in 4051 * progress, and treat the pages associated with the buffer 4052 * almost as being exclusive busy. Also the object paging_in_progress 4053 * flag is handled to make sure that the object doesn't become 4054 * inconsistant. 4055 * 4056 * Since I/O has not been initiated yet, certain buffer flags 4057 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 4058 * and should be ignored. 4059 */ 4060 void 4061 vfs_busy_pages(struct buf *bp, int clear_modify) 4062 { 4063 int i, bogus; 4064 vm_object_t obj; 4065 vm_ooffset_t foff; 4066 vm_page_t m; 4067 4068 if (!(bp->b_flags & B_VMIO)) 4069 return; 4070 4071 obj = bp->b_bufobj->bo_object; 4072 foff = bp->b_offset; 4073 KASSERT(bp->b_offset != NOOFFSET, 4074 ("vfs_busy_pages: no buffer offset")); 4075 VM_OBJECT_WLOCK(obj); 4076 vfs_drain_busy_pages(bp); 4077 if (bp->b_bufsize != 0) 4078 vfs_setdirty_locked_object(bp); 4079 bogus = 0; 4080 for (i = 0; i < bp->b_npages; i++) { 4081 m = bp->b_pages[i]; 4082 4083 if ((bp->b_flags & B_CLUSTER) == 0) { 4084 vm_object_pip_add(obj, 1); 4085 vm_page_sbusy(m); 4086 } 4087 /* 4088 * When readying a buffer for a read ( i.e 4089 * clear_modify == 0 ), it is important to do 4090 * bogus_page replacement for valid pages in 4091 * partially instantiated buffers. Partially 4092 * instantiated buffers can, in turn, occur when 4093 * reconstituting a buffer from its VM backing store 4094 * base. We only have to do this if B_CACHE is 4095 * clear ( which causes the I/O to occur in the 4096 * first place ). The replacement prevents the read 4097 * I/O from overwriting potentially dirty VM-backed 4098 * pages. XXX bogus page replacement is, uh, bogus. 4099 * It may not work properly with small-block devices. 4100 * We need to find a better way. 4101 */ 4102 if (clear_modify) { 4103 pmap_remove_write(m); 4104 vfs_page_set_validclean(bp, foff, m); 4105 } else if (m->valid == VM_PAGE_BITS_ALL && 4106 (bp->b_flags & B_CACHE) == 0) { 4107 bp->b_pages[i] = bogus_page; 4108 bogus++; 4109 } 4110 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4111 } 4112 VM_OBJECT_WUNLOCK(obj); 4113 if (bogus && (bp->b_flags & B_UNMAPPED) == 0) { 4114 BUF_CHECK_MAPPED(bp); 4115 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4116 bp->b_pages, bp->b_npages); 4117 } 4118 } 4119 4120 /* 4121 * vfs_bio_set_valid: 4122 * 4123 * Set the range within the buffer to valid. The range is 4124 * relative to the beginning of the buffer, b_offset. Note that 4125 * b_offset itself may be offset from the beginning of the first 4126 * page. 4127 */ 4128 void 4129 vfs_bio_set_valid(struct buf *bp, int base, int size) 4130 { 4131 int i, n; 4132 vm_page_t m; 4133 4134 if (!(bp->b_flags & B_VMIO)) 4135 return; 4136 4137 /* 4138 * Fixup base to be relative to beginning of first page. 4139 * Set initial n to be the maximum number of bytes in the 4140 * first page that can be validated. 4141 */ 4142 base += (bp->b_offset & PAGE_MASK); 4143 n = PAGE_SIZE - (base & PAGE_MASK); 4144 4145 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4146 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4147 m = bp->b_pages[i]; 4148 if (n > size) 4149 n = size; 4150 vm_page_set_valid_range(m, base & PAGE_MASK, n); 4151 base += n; 4152 size -= n; 4153 n = PAGE_SIZE; 4154 } 4155 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4156 } 4157 4158 /* 4159 * vfs_bio_clrbuf: 4160 * 4161 * If the specified buffer is a non-VMIO buffer, clear the entire 4162 * buffer. If the specified buffer is a VMIO buffer, clear and 4163 * validate only the previously invalid portions of the buffer. 4164 * This routine essentially fakes an I/O, so we need to clear 4165 * BIO_ERROR and B_INVAL. 4166 * 4167 * Note that while we only theoretically need to clear through b_bcount, 4168 * we go ahead and clear through b_bufsize. 4169 */ 4170 void 4171 vfs_bio_clrbuf(struct buf *bp) 4172 { 4173 int i, j, mask, sa, ea, slide; 4174 4175 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 4176 clrbuf(bp); 4177 return; 4178 } 4179 bp->b_flags &= ~B_INVAL; 4180 bp->b_ioflags &= ~BIO_ERROR; 4181 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4182 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 4183 (bp->b_offset & PAGE_MASK) == 0) { 4184 if (bp->b_pages[0] == bogus_page) 4185 goto unlock; 4186 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 4187 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object); 4188 if ((bp->b_pages[0]->valid & mask) == mask) 4189 goto unlock; 4190 if ((bp->b_pages[0]->valid & mask) == 0) { 4191 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize); 4192 bp->b_pages[0]->valid |= mask; 4193 goto unlock; 4194 } 4195 } 4196 sa = bp->b_offset & PAGE_MASK; 4197 slide = 0; 4198 for (i = 0; i < bp->b_npages; i++, sa = 0) { 4199 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize); 4200 ea = slide & PAGE_MASK; 4201 if (ea == 0) 4202 ea = PAGE_SIZE; 4203 if (bp->b_pages[i] == bogus_page) 4204 continue; 4205 j = sa / DEV_BSIZE; 4206 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 4207 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object); 4208 if ((bp->b_pages[i]->valid & mask) == mask) 4209 continue; 4210 if ((bp->b_pages[i]->valid & mask) == 0) 4211 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa); 4212 else { 4213 for (; sa < ea; sa += DEV_BSIZE, j++) { 4214 if ((bp->b_pages[i]->valid & (1 << j)) == 0) { 4215 pmap_zero_page_area(bp->b_pages[i], 4216 sa, DEV_BSIZE); 4217 } 4218 } 4219 } 4220 bp->b_pages[i]->valid |= mask; 4221 } 4222 unlock: 4223 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4224 bp->b_resid = 0; 4225 } 4226 4227 void 4228 vfs_bio_bzero_buf(struct buf *bp, int base, int size) 4229 { 4230 vm_page_t m; 4231 int i, n; 4232 4233 if ((bp->b_flags & B_UNMAPPED) == 0) { 4234 BUF_CHECK_MAPPED(bp); 4235 bzero(bp->b_data + base, size); 4236 } else { 4237 BUF_CHECK_UNMAPPED(bp); 4238 n = PAGE_SIZE - (base & PAGE_MASK); 4239 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4240 m = bp->b_pages[i]; 4241 if (n > size) 4242 n = size; 4243 pmap_zero_page_area(m, base & PAGE_MASK, n); 4244 base += n; 4245 size -= n; 4246 n = PAGE_SIZE; 4247 } 4248 } 4249 } 4250 4251 /* 4252 * vm_hold_load_pages and vm_hold_free_pages get pages into 4253 * a buffers address space. The pages are anonymous and are 4254 * not associated with a file object. 4255 */ 4256 static void 4257 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4258 { 4259 vm_offset_t pg; 4260 vm_page_t p; 4261 int index; 4262 4263 BUF_CHECK_MAPPED(bp); 4264 4265 to = round_page(to); 4266 from = round_page(from); 4267 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4268 4269 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 4270 tryagain: 4271 /* 4272 * note: must allocate system pages since blocking here 4273 * could interfere with paging I/O, no matter which 4274 * process we are. 4275 */ 4276 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ | 4277 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT)); 4278 if (p == NULL) { 4279 VM_WAIT; 4280 goto tryagain; 4281 } 4282 pmap_qenter(pg, &p, 1); 4283 bp->b_pages[index] = p; 4284 } 4285 bp->b_npages = index; 4286 } 4287 4288 /* Return pages associated with this buf to the vm system */ 4289 static void 4290 vm_hold_free_pages(struct buf *bp, int newbsize) 4291 { 4292 vm_offset_t from; 4293 vm_page_t p; 4294 int index, newnpages; 4295 4296 BUF_CHECK_MAPPED(bp); 4297 4298 from = round_page((vm_offset_t)bp->b_data + newbsize); 4299 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4300 if (bp->b_npages > newnpages) 4301 pmap_qremove(from, bp->b_npages - newnpages); 4302 for (index = newnpages; index < bp->b_npages; index++) { 4303 p = bp->b_pages[index]; 4304 bp->b_pages[index] = NULL; 4305 if (vm_page_sbusied(p)) 4306 printf("vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 4307 (intmax_t)bp->b_blkno, (intmax_t)bp->b_lblkno); 4308 p->wire_count--; 4309 vm_page_free(p); 4310 atomic_subtract_int(&vm_cnt.v_wire_count, 1); 4311 } 4312 bp->b_npages = newnpages; 4313 } 4314 4315 /* 4316 * Map an IO request into kernel virtual address space. 4317 * 4318 * All requests are (re)mapped into kernel VA space. 4319 * Notice that we use b_bufsize for the size of the buffer 4320 * to be mapped. b_bcount might be modified by the driver. 4321 * 4322 * Note that even if the caller determines that the address space should 4323 * be valid, a race or a smaller-file mapped into a larger space may 4324 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 4325 * check the return value. 4326 */ 4327 int 4328 vmapbuf(struct buf *bp, int mapbuf) 4329 { 4330 caddr_t kva; 4331 vm_prot_t prot; 4332 int pidx; 4333 4334 if (bp->b_bufsize < 0) 4335 return (-1); 4336 prot = VM_PROT_READ; 4337 if (bp->b_iocmd == BIO_READ) 4338 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 4339 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 4340 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages, 4341 btoc(MAXPHYS))) < 0) 4342 return (-1); 4343 bp->b_npages = pidx; 4344 if (mapbuf || !unmapped_buf_allowed) { 4345 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx); 4346 kva = bp->b_saveaddr; 4347 bp->b_saveaddr = bp->b_data; 4348 bp->b_data = kva + (((vm_offset_t)bp->b_data) & PAGE_MASK); 4349 bp->b_flags &= ~B_UNMAPPED; 4350 } else { 4351 bp->b_flags |= B_UNMAPPED; 4352 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK; 4353 bp->b_saveaddr = bp->b_data; 4354 bp->b_data = unmapped_buf; 4355 } 4356 return(0); 4357 } 4358 4359 /* 4360 * Free the io map PTEs associated with this IO operation. 4361 * We also invalidate the TLB entries and restore the original b_addr. 4362 */ 4363 void 4364 vunmapbuf(struct buf *bp) 4365 { 4366 int npages; 4367 4368 npages = bp->b_npages; 4369 if (bp->b_flags & B_UNMAPPED) 4370 bp->b_flags &= ~B_UNMAPPED; 4371 else 4372 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 4373 vm_page_unhold_pages(bp->b_pages, npages); 4374 4375 bp->b_data = bp->b_saveaddr; 4376 } 4377 4378 void 4379 bdone(struct buf *bp) 4380 { 4381 struct mtx *mtxp; 4382 4383 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4384 mtx_lock(mtxp); 4385 bp->b_flags |= B_DONE; 4386 wakeup(bp); 4387 mtx_unlock(mtxp); 4388 } 4389 4390 void 4391 bwait(struct buf *bp, u_char pri, const char *wchan) 4392 { 4393 struct mtx *mtxp; 4394 4395 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4396 mtx_lock(mtxp); 4397 while ((bp->b_flags & B_DONE) == 0) 4398 msleep(bp, mtxp, pri, wchan, 0); 4399 mtx_unlock(mtxp); 4400 } 4401 4402 int 4403 bufsync(struct bufobj *bo, int waitfor) 4404 { 4405 4406 return (VOP_FSYNC(bo->__bo_vnode, waitfor, curthread)); 4407 } 4408 4409 void 4410 bufstrategy(struct bufobj *bo, struct buf *bp) 4411 { 4412 int i = 0; 4413 struct vnode *vp; 4414 4415 vp = bp->b_vp; 4416 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 4417 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 4418 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 4419 i = VOP_STRATEGY(vp, bp); 4420 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 4421 } 4422 4423 void 4424 bufobj_wrefl(struct bufobj *bo) 4425 { 4426 4427 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4428 ASSERT_BO_WLOCKED(bo); 4429 bo->bo_numoutput++; 4430 } 4431 4432 void 4433 bufobj_wref(struct bufobj *bo) 4434 { 4435 4436 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4437 BO_LOCK(bo); 4438 bo->bo_numoutput++; 4439 BO_UNLOCK(bo); 4440 } 4441 4442 void 4443 bufobj_wdrop(struct bufobj *bo) 4444 { 4445 4446 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 4447 BO_LOCK(bo); 4448 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 4449 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 4450 bo->bo_flag &= ~BO_WWAIT; 4451 wakeup(&bo->bo_numoutput); 4452 } 4453 BO_UNLOCK(bo); 4454 } 4455 4456 int 4457 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 4458 { 4459 int error; 4460 4461 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 4462 ASSERT_BO_WLOCKED(bo); 4463 error = 0; 4464 while (bo->bo_numoutput) { 4465 bo->bo_flag |= BO_WWAIT; 4466 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo), 4467 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 4468 if (error) 4469 break; 4470 } 4471 return (error); 4472 } 4473 4474 void 4475 bpin(struct buf *bp) 4476 { 4477 struct mtx *mtxp; 4478 4479 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4480 mtx_lock(mtxp); 4481 bp->b_pin_count++; 4482 mtx_unlock(mtxp); 4483 } 4484 4485 void 4486 bunpin(struct buf *bp) 4487 { 4488 struct mtx *mtxp; 4489 4490 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4491 mtx_lock(mtxp); 4492 if (--bp->b_pin_count == 0) 4493 wakeup(bp); 4494 mtx_unlock(mtxp); 4495 } 4496 4497 void 4498 bunpin_wait(struct buf *bp) 4499 { 4500 struct mtx *mtxp; 4501 4502 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4503 mtx_lock(mtxp); 4504 while (bp->b_pin_count > 0) 4505 msleep(bp, mtxp, PRIBIO, "bwunpin", 0); 4506 mtx_unlock(mtxp); 4507 } 4508 4509 /* 4510 * Set bio_data or bio_ma for struct bio from the struct buf. 4511 */ 4512 void 4513 bdata2bio(struct buf *bp, struct bio *bip) 4514 { 4515 4516 if ((bp->b_flags & B_UNMAPPED) != 0) { 4517 KASSERT(unmapped_buf_allowed, ("unmapped")); 4518 bip->bio_ma = bp->b_pages; 4519 bip->bio_ma_n = bp->b_npages; 4520 bip->bio_data = unmapped_buf; 4521 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 4522 bip->bio_flags |= BIO_UNMAPPED; 4523 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) / 4524 PAGE_SIZE == bp->b_npages, 4525 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset, 4526 (long long)bip->bio_length, bip->bio_ma_n)); 4527 } else { 4528 bip->bio_data = bp->b_data; 4529 bip->bio_ma = NULL; 4530 } 4531 } 4532 4533 #include "opt_ddb.h" 4534 #ifdef DDB 4535 #include <ddb/ddb.h> 4536 4537 /* DDB command to show buffer data */ 4538 DB_SHOW_COMMAND(buffer, db_show_buffer) 4539 { 4540 /* get args */ 4541 struct buf *bp = (struct buf *)addr; 4542 4543 if (!have_addr) { 4544 db_printf("usage: show buffer <addr>\n"); 4545 return; 4546 } 4547 4548 db_printf("buf at %p\n", bp); 4549 db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n", 4550 (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags, 4551 PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS); 4552 db_printf( 4553 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 4554 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, " 4555 "b_dep = %p\n", 4556 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 4557 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 4558 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first); 4559 if (bp->b_npages) { 4560 int i; 4561 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 4562 for (i = 0; i < bp->b_npages; i++) { 4563 vm_page_t m; 4564 m = bp->b_pages[i]; 4565 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 4566 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 4567 if ((i + 1) < bp->b_npages) 4568 db_printf(","); 4569 } 4570 db_printf("\n"); 4571 } 4572 db_printf(" "); 4573 BUF_LOCKPRINTINFO(bp); 4574 } 4575 4576 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 4577 { 4578 struct buf *bp; 4579 int i; 4580 4581 for (i = 0; i < nbuf; i++) { 4582 bp = &buf[i]; 4583 if (BUF_ISLOCKED(bp)) { 4584 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4585 db_printf("\n"); 4586 } 4587 } 4588 } 4589 4590 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 4591 { 4592 struct vnode *vp; 4593 struct buf *bp; 4594 4595 if (!have_addr) { 4596 db_printf("usage: show vnodebufs <addr>\n"); 4597 return; 4598 } 4599 vp = (struct vnode *)addr; 4600 db_printf("Clean buffers:\n"); 4601 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 4602 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4603 db_printf("\n"); 4604 } 4605 db_printf("Dirty buffers:\n"); 4606 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 4607 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4608 db_printf("\n"); 4609 } 4610 } 4611 4612 DB_COMMAND(countfreebufs, db_coundfreebufs) 4613 { 4614 struct buf *bp; 4615 int i, used = 0, nfree = 0; 4616 4617 if (have_addr) { 4618 db_printf("usage: countfreebufs\n"); 4619 return; 4620 } 4621 4622 for (i = 0; i < nbuf; i++) { 4623 bp = &buf[i]; 4624 if ((bp->b_flags & B_INFREECNT) != 0) 4625 nfree++; 4626 else 4627 used++; 4628 } 4629 4630 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 4631 nfree + used); 4632 db_printf("numfreebuffers is %d\n", numfreebuffers); 4633 } 4634 #endif /* DDB */ 4635