1 /*- 2 * Copyright (c) 2004 Poul-Henning Kamp 3 * Copyright (c) 1994,1997 John S. Dyson 4 * Copyright (c) 2013 The FreeBSD Foundation 5 * All rights reserved. 6 * 7 * Portions of this software were developed by Konstantin Belousov 8 * under sponsorship from the FreeBSD Foundation. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 /* 33 * this file contains a new buffer I/O scheme implementing a coherent 34 * VM object and buffer cache scheme. Pains have been taken to make 35 * sure that the performance degradation associated with schemes such 36 * as this is not realized. 37 * 38 * Author: John S. Dyson 39 * Significant help during the development and debugging phases 40 * had been provided by David Greenman, also of the FreeBSD core team. 41 * 42 * see man buf(9) for more info. 43 */ 44 45 #include <sys/cdefs.h> 46 __FBSDID("$FreeBSD$"); 47 48 #include <sys/param.h> 49 #include <sys/systm.h> 50 #include <sys/bio.h> 51 #include <sys/conf.h> 52 #include <sys/buf.h> 53 #include <sys/devicestat.h> 54 #include <sys/eventhandler.h> 55 #include <sys/fail.h> 56 #include <sys/limits.h> 57 #include <sys/lock.h> 58 #include <sys/malloc.h> 59 #include <sys/mount.h> 60 #include <sys/mutex.h> 61 #include <sys/kernel.h> 62 #include <sys/kthread.h> 63 #include <sys/proc.h> 64 #include <sys/resourcevar.h> 65 #include <sys/rwlock.h> 66 #include <sys/sysctl.h> 67 #include <sys/vmem.h> 68 #include <sys/vmmeter.h> 69 #include <sys/vnode.h> 70 #include <geom/geom.h> 71 #include <vm/vm.h> 72 #include <vm/vm_param.h> 73 #include <vm/vm_kern.h> 74 #include <vm/vm_pageout.h> 75 #include <vm/vm_page.h> 76 #include <vm/vm_object.h> 77 #include <vm/vm_extern.h> 78 #include <vm/vm_map.h> 79 #include "opt_compat.h" 80 #include "opt_swap.h" 81 82 static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer"); 83 84 struct bio_ops bioops; /* I/O operation notification */ 85 86 struct buf_ops buf_ops_bio = { 87 .bop_name = "buf_ops_bio", 88 .bop_write = bufwrite, 89 .bop_strategy = bufstrategy, 90 .bop_sync = bufsync, 91 .bop_bdflush = bufbdflush, 92 }; 93 94 /* 95 * XXX buf is global because kern_shutdown.c and ffs_checkoverlap has 96 * carnal knowledge of buffers. This knowledge should be moved to vfs_bio.c. 97 */ 98 struct buf *buf; /* buffer header pool */ 99 caddr_t unmapped_buf; 100 101 /* Used below and for softdep flushing threads in ufs/ffs/ffs_softdep.c */ 102 struct proc *bufdaemonproc; 103 104 static int inmem(struct vnode *vp, daddr_t blkno); 105 static void vm_hold_free_pages(struct buf *bp, int newbsize); 106 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from, 107 vm_offset_t to); 108 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m); 109 static void vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, 110 vm_page_t m); 111 static void vfs_clean_pages_dirty_buf(struct buf *bp); 112 static void vfs_setdirty_locked_object(struct buf *bp); 113 static void vfs_vmio_release(struct buf *bp); 114 static int vfs_bio_clcheck(struct vnode *vp, int size, 115 daddr_t lblkno, daddr_t blkno); 116 static int buf_flush(struct vnode *vp, int); 117 static int flushbufqueues(struct vnode *, int, int); 118 static void buf_daemon(void); 119 static void bremfreel(struct buf *bp); 120 static __inline void bd_wakeup(void); 121 static int sysctl_runningspace(SYSCTL_HANDLER_ARGS); 122 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 123 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 124 static int sysctl_bufspace(SYSCTL_HANDLER_ARGS); 125 #endif 126 127 int vmiodirenable = TRUE; 128 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, 129 "Use the VM system for directory writes"); 130 long runningbufspace; 131 SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 132 "Amount of presently outstanding async buffer io"); 133 static long bufspace; 134 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 135 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 136 SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD, 137 &bufspace, 0, sysctl_bufspace, "L", "Virtual memory used for buffers"); 138 #else 139 SYSCTL_LONG(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, 140 "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 CTASSERT(MAXBCACHEBUF >= MAXBSIZE); 809 mtx_init(&bqclean, "bufq clean lock", NULL, MTX_DEF); 810 mtx_init(&bqdirty, "bufq dirty lock", NULL, MTX_DEF); 811 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 812 rw_init(&nblock, "needsbuffer lock"); 813 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 814 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF); 815 816 /* next, make a null set of free lists */ 817 for (i = 0; i < BUFFER_QUEUES; i++) 818 TAILQ_INIT(&bufqueues[i]); 819 820 /* finally, initialize each buffer header and stick on empty q */ 821 for (i = 0; i < nbuf; i++) { 822 bp = &buf[i]; 823 bzero(bp, sizeof *bp); 824 bp->b_flags = B_INVAL | B_INFREECNT; 825 bp->b_rcred = NOCRED; 826 bp->b_wcred = NOCRED; 827 bp->b_qindex = QUEUE_EMPTY; 828 bp->b_xflags = 0; 829 LIST_INIT(&bp->b_dep); 830 BUF_LOCKINIT(bp); 831 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 832 #ifdef INVARIANTS 833 bq_len[QUEUE_EMPTY]++; 834 #endif 835 } 836 837 /* 838 * maxbufspace is the absolute maximum amount of buffer space we are 839 * allowed to reserve in KVM and in real terms. The absolute maximum 840 * is nominally used by buf_daemon. hibufspace is the nominal maximum 841 * used by most other processes. The differential is required to 842 * ensure that buf_daemon is able to run when other processes might 843 * be blocked waiting for buffer space. 844 * 845 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 846 * this may result in KVM fragmentation which is not handled optimally 847 * by the system. 848 */ 849 maxbufspace = (long)nbuf * BKVASIZE; 850 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - MAXBCACHEBUF * 10); 851 lobufspace = hibufspace - MAXBCACHEBUF; 852 853 /* 854 * Note: The 16 MiB upper limit for hirunningspace was chosen 855 * arbitrarily and may need further tuning. It corresponds to 856 * 128 outstanding write IO requests (if IO size is 128 KiB), 857 * which fits with many RAID controllers' tagged queuing limits. 858 * The lower 1 MiB limit is the historical upper limit for 859 * hirunningspace. 860 */ 861 hirunningspace = lmax(lmin(roundup(hibufspace / 64, MAXBCACHEBUF), 862 16 * 1024 * 1024), 1024 * 1024); 863 lorunningspace = roundup((hirunningspace * 2) / 3, MAXBCACHEBUF); 864 865 /* 866 * Limit the amount of malloc memory since it is wired permanently into 867 * the kernel space. Even though this is accounted for in the buffer 868 * allocation, we don't want the malloced region to grow uncontrolled. 869 * The malloc scheme improves memory utilization significantly on average 870 * (small) directories. 871 */ 872 maxbufmallocspace = hibufspace / 20; 873 874 /* 875 * Reduce the chance of a deadlock occuring by limiting the number 876 * of delayed-write dirty buffers we allow to stack up. 877 */ 878 hidirtybuffers = nbuf / 4 + 20; 879 dirtybufthresh = hidirtybuffers * 9 / 10; 880 numdirtybuffers = 0; 881 /* 882 * To support extreme low-memory systems, make sure hidirtybuffers cannot 883 * eat up all available buffer space. This occurs when our minimum cannot 884 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 885 * BKVASIZE'd buffers. 886 */ 887 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 888 hidirtybuffers >>= 1; 889 } 890 lodirtybuffers = hidirtybuffers / 2; 891 892 /* 893 * Try to keep the number of free buffers in the specified range, 894 * and give special processes (e.g. like buf_daemon) access to an 895 * emergency reserve. 896 */ 897 lofreebuffers = nbuf / 18 + 5; 898 hifreebuffers = 2 * lofreebuffers; 899 numfreebuffers = nbuf; 900 901 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ | 902 VM_ALLOC_NORMAL | VM_ALLOC_WIRED); 903 unmapped_buf = (caddr_t)kva_alloc(MAXPHYS); 904 } 905 906 #ifdef INVARIANTS 907 static inline void 908 vfs_buf_check_mapped(struct buf *bp) 909 { 910 911 KASSERT((bp->b_flags & B_UNMAPPED) == 0, 912 ("mapped buf %p %x", bp, bp->b_flags)); 913 KASSERT(bp->b_kvabase != unmapped_buf, 914 ("mapped buf: b_kvabase was not updated %p", bp)); 915 KASSERT(bp->b_data != unmapped_buf, 916 ("mapped buf: b_data was not updated %p", bp)); 917 } 918 919 static inline void 920 vfs_buf_check_unmapped(struct buf *bp) 921 { 922 923 KASSERT((bp->b_flags & B_UNMAPPED) == B_UNMAPPED, 924 ("unmapped buf %p %x", bp, bp->b_flags)); 925 KASSERT(bp->b_kvabase == unmapped_buf, 926 ("unmapped buf: corrupted b_kvabase %p", bp)); 927 KASSERT(bp->b_data == unmapped_buf, 928 ("unmapped buf: corrupted b_data %p", bp)); 929 } 930 931 #define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp) 932 #define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp) 933 #else 934 #define BUF_CHECK_MAPPED(bp) do {} while (0) 935 #define BUF_CHECK_UNMAPPED(bp) do {} while (0) 936 #endif 937 938 static void 939 bpmap_qenter(struct buf *bp) 940 { 941 942 BUF_CHECK_MAPPED(bp); 943 944 /* 945 * bp->b_data is relative to bp->b_offset, but 946 * bp->b_offset may be offset into the first page. 947 */ 948 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data); 949 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages); 950 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 951 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 952 } 953 954 /* 955 * bfreekva() - free the kva allocation for a buffer. 956 * 957 * Since this call frees up buffer space, we call bufspacewakeup(). 958 */ 959 static void 960 bfreekva(struct buf *bp) 961 { 962 963 if (bp->b_kvasize == 0) 964 return; 965 966 atomic_add_int(&buffreekvacnt, 1); 967 atomic_subtract_long(&bufspace, bp->b_kvasize); 968 if ((bp->b_flags & B_UNMAPPED) == 0) { 969 BUF_CHECK_MAPPED(bp); 970 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, 971 bp->b_kvasize); 972 } else { 973 BUF_CHECK_UNMAPPED(bp); 974 if ((bp->b_flags & B_KVAALLOC) != 0) { 975 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvaalloc, 976 bp->b_kvasize); 977 } 978 atomic_subtract_long(&unmapped_bufspace, bp->b_kvasize); 979 bp->b_flags &= ~(B_UNMAPPED | B_KVAALLOC); 980 } 981 bp->b_kvasize = 0; 982 bufspacewakeup(); 983 } 984 985 /* 986 * binsfree: 987 * 988 * Insert the buffer into the appropriate free list. 989 */ 990 static void 991 binsfree(struct buf *bp, int qindex) 992 { 993 struct mtx *olock, *nlock; 994 995 BUF_ASSERT_XLOCKED(bp); 996 997 nlock = bqlock(qindex); 998 /* Handle delayed bremfree() processing. */ 999 if (bp->b_flags & B_REMFREE) { 1000 olock = bqlock(bp->b_qindex); 1001 mtx_lock(olock); 1002 bremfreel(bp); 1003 if (olock != nlock) { 1004 mtx_unlock(olock); 1005 mtx_lock(nlock); 1006 } 1007 } else 1008 mtx_lock(nlock); 1009 1010 if (bp->b_qindex != QUEUE_NONE) 1011 panic("binsfree: free buffer onto another queue???"); 1012 1013 bp->b_qindex = qindex; 1014 if (bp->b_flags & B_AGE) 1015 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1016 else 1017 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1018 #ifdef INVARIANTS 1019 bq_len[bp->b_qindex]++; 1020 #endif 1021 mtx_unlock(nlock); 1022 1023 /* 1024 * Something we can maybe free or reuse. 1025 */ 1026 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1027 bufspacewakeup(); 1028 1029 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI)) 1030 bufcountadd(bp); 1031 } 1032 1033 /* 1034 * bremfree: 1035 * 1036 * Mark the buffer for removal from the appropriate free list. 1037 * 1038 */ 1039 void 1040 bremfree(struct buf *bp) 1041 { 1042 1043 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1044 KASSERT((bp->b_flags & B_REMFREE) == 0, 1045 ("bremfree: buffer %p already marked for delayed removal.", bp)); 1046 KASSERT(bp->b_qindex != QUEUE_NONE, 1047 ("bremfree: buffer %p not on a queue.", bp)); 1048 BUF_ASSERT_XLOCKED(bp); 1049 1050 bp->b_flags |= B_REMFREE; 1051 bufcountsub(bp); 1052 } 1053 1054 /* 1055 * bremfreef: 1056 * 1057 * Force an immediate removal from a free list. Used only in nfs when 1058 * it abuses the b_freelist pointer. 1059 */ 1060 void 1061 bremfreef(struct buf *bp) 1062 { 1063 struct mtx *qlock; 1064 1065 qlock = bqlock(bp->b_qindex); 1066 mtx_lock(qlock); 1067 bremfreel(bp); 1068 mtx_unlock(qlock); 1069 } 1070 1071 /* 1072 * bremfreel: 1073 * 1074 * Removes a buffer from the free list, must be called with the 1075 * correct qlock held. 1076 */ 1077 static void 1078 bremfreel(struct buf *bp) 1079 { 1080 1081 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X", 1082 bp, bp->b_vp, bp->b_flags); 1083 KASSERT(bp->b_qindex != QUEUE_NONE, 1084 ("bremfreel: buffer %p not on a queue.", bp)); 1085 BUF_ASSERT_XLOCKED(bp); 1086 mtx_assert(bqlock(bp->b_qindex), MA_OWNED); 1087 1088 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 1089 #ifdef INVARIANTS 1090 KASSERT(bq_len[bp->b_qindex] >= 1, ("queue %d underflow", 1091 bp->b_qindex)); 1092 bq_len[bp->b_qindex]--; 1093 #endif 1094 bp->b_qindex = QUEUE_NONE; 1095 /* 1096 * If this was a delayed bremfree() we only need to remove the buffer 1097 * from the queue and return the stats are already done. 1098 */ 1099 if (bp->b_flags & B_REMFREE) { 1100 bp->b_flags &= ~B_REMFREE; 1101 return; 1102 } 1103 bufcountsub(bp); 1104 } 1105 1106 /* 1107 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 1108 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 1109 * the buffer is valid and we do not have to do anything. 1110 */ 1111 void 1112 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, 1113 int cnt, struct ucred * cred) 1114 { 1115 struct buf *rabp; 1116 int i; 1117 1118 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 1119 if (inmem(vp, *rablkno)) 1120 continue; 1121 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 1122 1123 if ((rabp->b_flags & B_CACHE) == 0) { 1124 if (!TD_IS_IDLETHREAD(curthread)) 1125 curthread->td_ru.ru_inblock++; 1126 rabp->b_flags |= B_ASYNC; 1127 rabp->b_flags &= ~B_INVAL; 1128 rabp->b_ioflags &= ~BIO_ERROR; 1129 rabp->b_iocmd = BIO_READ; 1130 if (rabp->b_rcred == NOCRED && cred != NOCRED) 1131 rabp->b_rcred = crhold(cred); 1132 vfs_busy_pages(rabp, 0); 1133 BUF_KERNPROC(rabp); 1134 rabp->b_iooffset = dbtob(rabp->b_blkno); 1135 bstrategy(rabp); 1136 } else { 1137 brelse(rabp); 1138 } 1139 } 1140 } 1141 1142 /* 1143 * Entry point for bread() and breadn() via #defines in sys/buf.h. 1144 * 1145 * Get a buffer with the specified data. Look in the cache first. We 1146 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 1147 * is set, the buffer is valid and we do not have to do anything, see 1148 * getblk(). Also starts asynchronous I/O on read-ahead blocks. 1149 */ 1150 int 1151 breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno, 1152 int *rabsize, int cnt, struct ucred *cred, int flags, struct buf **bpp) 1153 { 1154 struct buf *bp; 1155 int rv = 0, readwait = 0; 1156 1157 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 1158 /* 1159 * Can only return NULL if GB_LOCK_NOWAIT flag is specified. 1160 */ 1161 *bpp = bp = getblk(vp, blkno, size, 0, 0, flags); 1162 if (bp == NULL) 1163 return (EBUSY); 1164 1165 /* if not found in cache, do some I/O */ 1166 if ((bp->b_flags & B_CACHE) == 0) { 1167 if (!TD_IS_IDLETHREAD(curthread)) 1168 curthread->td_ru.ru_inblock++; 1169 bp->b_iocmd = BIO_READ; 1170 bp->b_flags &= ~B_INVAL; 1171 bp->b_ioflags &= ~BIO_ERROR; 1172 if (bp->b_rcred == NOCRED && cred != NOCRED) 1173 bp->b_rcred = crhold(cred); 1174 vfs_busy_pages(bp, 0); 1175 bp->b_iooffset = dbtob(bp->b_blkno); 1176 bstrategy(bp); 1177 ++readwait; 1178 } 1179 1180 breada(vp, rablkno, rabsize, cnt, cred); 1181 1182 if (readwait) { 1183 rv = bufwait(bp); 1184 } 1185 return (rv); 1186 } 1187 1188 /* 1189 * Write, release buffer on completion. (Done by iodone 1190 * if async). Do not bother writing anything if the buffer 1191 * is invalid. 1192 * 1193 * Note that we set B_CACHE here, indicating that buffer is 1194 * fully valid and thus cacheable. This is true even of NFS 1195 * now so we set it generally. This could be set either here 1196 * or in biodone() since the I/O is synchronous. We put it 1197 * here. 1198 */ 1199 int 1200 bufwrite(struct buf *bp) 1201 { 1202 int oldflags; 1203 struct vnode *vp; 1204 long space; 1205 int vp_md; 1206 1207 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1208 if ((bp->b_bufobj->bo_flag & BO_DEAD) != 0) { 1209 bp->b_flags |= B_INVAL | B_RELBUF; 1210 bp->b_flags &= ~B_CACHE; 1211 brelse(bp); 1212 return (ENXIO); 1213 } 1214 if (bp->b_flags & B_INVAL) { 1215 brelse(bp); 1216 return (0); 1217 } 1218 1219 if (bp->b_flags & B_BARRIER) 1220 barrierwrites++; 1221 1222 oldflags = bp->b_flags; 1223 1224 BUF_ASSERT_HELD(bp); 1225 1226 if (bp->b_pin_count > 0) 1227 bunpin_wait(bp); 1228 1229 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 1230 ("FFS background buffer should not get here %p", bp)); 1231 1232 vp = bp->b_vp; 1233 if (vp) 1234 vp_md = vp->v_vflag & VV_MD; 1235 else 1236 vp_md = 0; 1237 1238 /* 1239 * Mark the buffer clean. Increment the bufobj write count 1240 * before bundirty() call, to prevent other thread from seeing 1241 * empty dirty list and zero counter for writes in progress, 1242 * falsely indicating that the bufobj is clean. 1243 */ 1244 bufobj_wref(bp->b_bufobj); 1245 bundirty(bp); 1246 1247 bp->b_flags &= ~B_DONE; 1248 bp->b_ioflags &= ~BIO_ERROR; 1249 bp->b_flags |= B_CACHE; 1250 bp->b_iocmd = BIO_WRITE; 1251 1252 vfs_busy_pages(bp, 1); 1253 1254 /* 1255 * Normal bwrites pipeline writes 1256 */ 1257 bp->b_runningbufspace = bp->b_bufsize; 1258 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace); 1259 1260 if (!TD_IS_IDLETHREAD(curthread)) 1261 curthread->td_ru.ru_oublock++; 1262 if (oldflags & B_ASYNC) 1263 BUF_KERNPROC(bp); 1264 bp->b_iooffset = dbtob(bp->b_blkno); 1265 bstrategy(bp); 1266 1267 if ((oldflags & B_ASYNC) == 0) { 1268 int rtval = bufwait(bp); 1269 brelse(bp); 1270 return (rtval); 1271 } else if (space > hirunningspace) { 1272 /* 1273 * don't allow the async write to saturate the I/O 1274 * system. We will not deadlock here because 1275 * we are blocking waiting for I/O that is already in-progress 1276 * to complete. We do not block here if it is the update 1277 * or syncer daemon trying to clean up as that can lead 1278 * to deadlock. 1279 */ 1280 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 1281 waitrunningbufspace(); 1282 } 1283 1284 return (0); 1285 } 1286 1287 void 1288 bufbdflush(struct bufobj *bo, struct buf *bp) 1289 { 1290 struct buf *nbp; 1291 1292 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 1293 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 1294 altbufferflushes++; 1295 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 1296 BO_LOCK(bo); 1297 /* 1298 * Try to find a buffer to flush. 1299 */ 1300 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 1301 if ((nbp->b_vflags & BV_BKGRDINPROG) || 1302 BUF_LOCK(nbp, 1303 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 1304 continue; 1305 if (bp == nbp) 1306 panic("bdwrite: found ourselves"); 1307 BO_UNLOCK(bo); 1308 /* Don't countdeps with the bo lock held. */ 1309 if (buf_countdeps(nbp, 0)) { 1310 BO_LOCK(bo); 1311 BUF_UNLOCK(nbp); 1312 continue; 1313 } 1314 if (nbp->b_flags & B_CLUSTEROK) { 1315 vfs_bio_awrite(nbp); 1316 } else { 1317 bremfree(nbp); 1318 bawrite(nbp); 1319 } 1320 dirtybufferflushes++; 1321 break; 1322 } 1323 if (nbp == NULL) 1324 BO_UNLOCK(bo); 1325 } 1326 } 1327 1328 /* 1329 * Delayed write. (Buffer is marked dirty). Do not bother writing 1330 * anything if the buffer is marked invalid. 1331 * 1332 * Note that since the buffer must be completely valid, we can safely 1333 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 1334 * biodone() in order to prevent getblk from writing the buffer 1335 * out synchronously. 1336 */ 1337 void 1338 bdwrite(struct buf *bp) 1339 { 1340 struct thread *td = curthread; 1341 struct vnode *vp; 1342 struct bufobj *bo; 1343 1344 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1345 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1346 KASSERT((bp->b_flags & B_BARRIER) == 0, 1347 ("Barrier request in delayed write %p", bp)); 1348 BUF_ASSERT_HELD(bp); 1349 1350 if (bp->b_flags & B_INVAL) { 1351 brelse(bp); 1352 return; 1353 } 1354 1355 /* 1356 * If we have too many dirty buffers, don't create any more. 1357 * If we are wildly over our limit, then force a complete 1358 * cleanup. Otherwise, just keep the situation from getting 1359 * out of control. Note that we have to avoid a recursive 1360 * disaster and not try to clean up after our own cleanup! 1361 */ 1362 vp = bp->b_vp; 1363 bo = bp->b_bufobj; 1364 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 1365 td->td_pflags |= TDP_INBDFLUSH; 1366 BO_BDFLUSH(bo, bp); 1367 td->td_pflags &= ~TDP_INBDFLUSH; 1368 } else 1369 recursiveflushes++; 1370 1371 bdirty(bp); 1372 /* 1373 * Set B_CACHE, indicating that the buffer is fully valid. This is 1374 * true even of NFS now. 1375 */ 1376 bp->b_flags |= B_CACHE; 1377 1378 /* 1379 * This bmap keeps the system from needing to do the bmap later, 1380 * perhaps when the system is attempting to do a sync. Since it 1381 * is likely that the indirect block -- or whatever other datastructure 1382 * that the filesystem needs is still in memory now, it is a good 1383 * thing to do this. Note also, that if the pageout daemon is 1384 * requesting a sync -- there might not be enough memory to do 1385 * the bmap then... So, this is important to do. 1386 */ 1387 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 1388 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 1389 } 1390 1391 /* 1392 * Set the *dirty* buffer range based upon the VM system dirty 1393 * pages. 1394 * 1395 * Mark the buffer pages as clean. We need to do this here to 1396 * satisfy the vnode_pager and the pageout daemon, so that it 1397 * thinks that the pages have been "cleaned". Note that since 1398 * the pages are in a delayed write buffer -- the VFS layer 1399 * "will" see that the pages get written out on the next sync, 1400 * or perhaps the cluster will be completed. 1401 */ 1402 vfs_clean_pages_dirty_buf(bp); 1403 bqrelse(bp); 1404 1405 /* 1406 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 1407 * due to the softdep code. 1408 */ 1409 } 1410 1411 /* 1412 * bdirty: 1413 * 1414 * Turn buffer into delayed write request. We must clear BIO_READ and 1415 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 1416 * itself to properly update it in the dirty/clean lists. We mark it 1417 * B_DONE to ensure that any asynchronization of the buffer properly 1418 * clears B_DONE ( else a panic will occur later ). 1419 * 1420 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 1421 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 1422 * should only be called if the buffer is known-good. 1423 * 1424 * Since the buffer is not on a queue, we do not update the numfreebuffers 1425 * count. 1426 * 1427 * The buffer must be on QUEUE_NONE. 1428 */ 1429 void 1430 bdirty(struct buf *bp) 1431 { 1432 1433 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 1434 bp, bp->b_vp, bp->b_flags); 1435 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1436 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1437 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1438 BUF_ASSERT_HELD(bp); 1439 bp->b_flags &= ~(B_RELBUF); 1440 bp->b_iocmd = BIO_WRITE; 1441 1442 if ((bp->b_flags & B_DELWRI) == 0) { 1443 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 1444 reassignbuf(bp); 1445 bdirtyadd(); 1446 } 1447 } 1448 1449 /* 1450 * bundirty: 1451 * 1452 * Clear B_DELWRI for buffer. 1453 * 1454 * Since the buffer is not on a queue, we do not update the numfreebuffers 1455 * count. 1456 * 1457 * The buffer must be on QUEUE_NONE. 1458 */ 1459 1460 void 1461 bundirty(struct buf *bp) 1462 { 1463 1464 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1465 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1466 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1467 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1468 BUF_ASSERT_HELD(bp); 1469 1470 if (bp->b_flags & B_DELWRI) { 1471 bp->b_flags &= ~B_DELWRI; 1472 reassignbuf(bp); 1473 bdirtysub(); 1474 } 1475 /* 1476 * Since it is now being written, we can clear its deferred write flag. 1477 */ 1478 bp->b_flags &= ~B_DEFERRED; 1479 } 1480 1481 /* 1482 * bawrite: 1483 * 1484 * Asynchronous write. Start output on a buffer, but do not wait for 1485 * it to complete. The buffer is released when the output completes. 1486 * 1487 * bwrite() ( or the VOP routine anyway ) is responsible for handling 1488 * B_INVAL buffers. Not us. 1489 */ 1490 void 1491 bawrite(struct buf *bp) 1492 { 1493 1494 bp->b_flags |= B_ASYNC; 1495 (void) bwrite(bp); 1496 } 1497 1498 /* 1499 * babarrierwrite: 1500 * 1501 * Asynchronous barrier write. Start output on a buffer, but do not 1502 * wait for it to complete. Place a write barrier after this write so 1503 * that this buffer and all buffers written before it are committed to 1504 * the disk before any buffers written after this write are committed 1505 * to the disk. The buffer is released when the output completes. 1506 */ 1507 void 1508 babarrierwrite(struct buf *bp) 1509 { 1510 1511 bp->b_flags |= B_ASYNC | B_BARRIER; 1512 (void) bwrite(bp); 1513 } 1514 1515 /* 1516 * bbarrierwrite: 1517 * 1518 * Synchronous barrier write. Start output on a buffer and wait for 1519 * it to complete. Place a write barrier after this write so that 1520 * this buffer and all buffers written before it are committed to 1521 * the disk before any buffers written after this write are committed 1522 * to the disk. The buffer is released when the output completes. 1523 */ 1524 int 1525 bbarrierwrite(struct buf *bp) 1526 { 1527 1528 bp->b_flags |= B_BARRIER; 1529 return (bwrite(bp)); 1530 } 1531 1532 /* 1533 * bwillwrite: 1534 * 1535 * Called prior to the locking of any vnodes when we are expecting to 1536 * write. We do not want to starve the buffer cache with too many 1537 * dirty buffers so we block here. By blocking prior to the locking 1538 * of any vnodes we attempt to avoid the situation where a locked vnode 1539 * prevents the various system daemons from flushing related buffers. 1540 */ 1541 void 1542 bwillwrite(void) 1543 { 1544 1545 if (numdirtybuffers >= hidirtybuffers) { 1546 mtx_lock(&bdirtylock); 1547 while (numdirtybuffers >= hidirtybuffers) { 1548 bdirtywait = 1; 1549 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4), 1550 "flswai", 0); 1551 } 1552 mtx_unlock(&bdirtylock); 1553 } 1554 } 1555 1556 /* 1557 * Return true if we have too many dirty buffers. 1558 */ 1559 int 1560 buf_dirty_count_severe(void) 1561 { 1562 1563 return(numdirtybuffers >= hidirtybuffers); 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_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) { 1598 BO_LOCK(bp->b_bufobj); 1599 bp->b_vflags &= ~BV_BKGRDERR; 1600 BO_UNLOCK(bp->b_bufobj); 1601 bdirty(bp); 1602 } 1603 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 1604 bp->b_error == EIO && !(bp->b_flags & B_INVAL)) { 1605 /* 1606 * Failed write, redirty. Must clear BIO_ERROR to prevent 1607 * pages from being scrapped. If the error is anything 1608 * other than an I/O error (EIO), assume that retrying 1609 * is futile. 1610 */ 1611 bp->b_ioflags &= ~BIO_ERROR; 1612 bdirty(bp); 1613 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 1614 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 1615 /* 1616 * Either a failed I/O or we were asked to free or not 1617 * cache the buffer. 1618 */ 1619 bp->b_flags |= B_INVAL; 1620 if (!LIST_EMPTY(&bp->b_dep)) 1621 buf_deallocate(bp); 1622 if (bp->b_flags & B_DELWRI) 1623 bdirtysub(); 1624 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1625 if ((bp->b_flags & B_VMIO) == 0) { 1626 if (bp->b_bufsize) 1627 allocbuf(bp, 0); 1628 if (bp->b_vp) 1629 brelvp(bp); 1630 } 1631 } 1632 1633 /* 1634 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1635 * is called with B_DELWRI set, the underlying pages may wind up 1636 * getting freed causing a previous write (bdwrite()) to get 'lost' 1637 * because pages associated with a B_DELWRI bp are marked clean. 1638 * 1639 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1640 * if B_DELWRI is set. 1641 */ 1642 if (bp->b_flags & B_DELWRI) 1643 bp->b_flags &= ~B_RELBUF; 1644 1645 /* 1646 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1647 * constituted, not even NFS buffers now. Two flags effect this. If 1648 * B_INVAL, the struct buf is invalidated but the VM object is kept 1649 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1650 * 1651 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 1652 * invalidated. BIO_ERROR cannot be set for a failed write unless the 1653 * buffer is also B_INVAL because it hits the re-dirtying code above. 1654 * 1655 * Normally we can do this whether a buffer is B_DELWRI or not. If 1656 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1657 * the commit state and we cannot afford to lose the buffer. If the 1658 * buffer has a background write in progress, we need to keep it 1659 * around to prevent it from being reconstituted and starting a second 1660 * background write. 1661 */ 1662 if ((bp->b_flags & B_VMIO) 1663 && !(bp->b_vp->v_mount != NULL && 1664 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 1665 !vn_isdisk(bp->b_vp, NULL) && 1666 (bp->b_flags & B_DELWRI)) 1667 ) { 1668 1669 int i, j, resid; 1670 vm_page_t m; 1671 off_t foff; 1672 vm_pindex_t poff; 1673 vm_object_t obj; 1674 1675 obj = bp->b_bufobj->bo_object; 1676 1677 /* 1678 * Get the base offset and length of the buffer. Note that 1679 * in the VMIO case if the buffer block size is not 1680 * page-aligned then b_data pointer may not be page-aligned. 1681 * But our b_pages[] array *IS* page aligned. 1682 * 1683 * block sizes less then DEV_BSIZE (usually 512) are not 1684 * supported due to the page granularity bits (m->valid, 1685 * m->dirty, etc...). 1686 * 1687 * See man buf(9) for more information 1688 */ 1689 resid = bp->b_bufsize; 1690 foff = bp->b_offset; 1691 for (i = 0; i < bp->b_npages; i++) { 1692 int had_bogus = 0; 1693 1694 m = bp->b_pages[i]; 1695 1696 /* 1697 * If we hit a bogus page, fixup *all* the bogus pages 1698 * now. 1699 */ 1700 if (m == bogus_page) { 1701 poff = OFF_TO_IDX(bp->b_offset); 1702 had_bogus = 1; 1703 1704 VM_OBJECT_RLOCK(obj); 1705 for (j = i; j < bp->b_npages; j++) { 1706 vm_page_t mtmp; 1707 mtmp = bp->b_pages[j]; 1708 if (mtmp == bogus_page) { 1709 mtmp = vm_page_lookup(obj, poff + j); 1710 if (!mtmp) { 1711 panic("brelse: page missing\n"); 1712 } 1713 bp->b_pages[j] = mtmp; 1714 } 1715 } 1716 VM_OBJECT_RUNLOCK(obj); 1717 1718 if ((bp->b_flags & (B_INVAL | B_UNMAPPED)) == 0) { 1719 BUF_CHECK_MAPPED(bp); 1720 pmap_qenter( 1721 trunc_page((vm_offset_t)bp->b_data), 1722 bp->b_pages, bp->b_npages); 1723 } 1724 m = bp->b_pages[i]; 1725 } 1726 if ((bp->b_flags & B_NOCACHE) || 1727 (bp->b_ioflags & BIO_ERROR && 1728 bp->b_iocmd == BIO_READ)) { 1729 int poffset = foff & PAGE_MASK; 1730 int presid = resid > (PAGE_SIZE - poffset) ? 1731 (PAGE_SIZE - poffset) : resid; 1732 1733 KASSERT(presid >= 0, ("brelse: extra page")); 1734 VM_OBJECT_WLOCK(obj); 1735 while (vm_page_xbusied(m)) { 1736 vm_page_lock(m); 1737 VM_OBJECT_WUNLOCK(obj); 1738 vm_page_busy_sleep(m, "mbncsh"); 1739 VM_OBJECT_WLOCK(obj); 1740 } 1741 if (pmap_page_wired_mappings(m) == 0) 1742 vm_page_set_invalid(m, poffset, presid); 1743 VM_OBJECT_WUNLOCK(obj); 1744 if (had_bogus) 1745 printf("avoided corruption bug in bogus_page/brelse code\n"); 1746 } 1747 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1748 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1749 } 1750 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1751 vfs_vmio_release(bp); 1752 1753 } else if (bp->b_flags & B_VMIO) { 1754 1755 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1756 vfs_vmio_release(bp); 1757 } 1758 1759 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) { 1760 if (bp->b_bufsize != 0) 1761 allocbuf(bp, 0); 1762 if (bp->b_vp != NULL) 1763 brelvp(bp); 1764 } 1765 1766 /* 1767 * If the buffer has junk contents signal it and eventually 1768 * clean up B_DELWRI and diassociate the vnode so that gbincore() 1769 * doesn't find it. 1770 */ 1771 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 1772 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 1773 bp->b_flags |= B_INVAL; 1774 if (bp->b_flags & B_INVAL) { 1775 if (bp->b_flags & B_DELWRI) 1776 bundirty(bp); 1777 if (bp->b_vp) 1778 brelvp(bp); 1779 } 1780 1781 /* buffers with no memory */ 1782 if (bp->b_bufsize == 0) { 1783 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1784 if (bp->b_vflags & BV_BKGRDINPROG) 1785 panic("losing buffer 1"); 1786 if (bp->b_kvasize) 1787 qindex = QUEUE_EMPTYKVA; 1788 else 1789 qindex = QUEUE_EMPTY; 1790 bp->b_flags |= B_AGE; 1791 /* buffers with junk contents */ 1792 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 1793 (bp->b_ioflags & BIO_ERROR)) { 1794 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1795 if (bp->b_vflags & BV_BKGRDINPROG) 1796 panic("losing buffer 2"); 1797 qindex = QUEUE_CLEAN; 1798 bp->b_flags |= B_AGE; 1799 /* remaining buffers */ 1800 } else if (bp->b_flags & B_DELWRI) 1801 qindex = QUEUE_DIRTY; 1802 else 1803 qindex = QUEUE_CLEAN; 1804 1805 binsfree(bp, qindex); 1806 1807 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 1808 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1809 panic("brelse: not dirty"); 1810 /* unlock */ 1811 BUF_UNLOCK(bp); 1812 } 1813 1814 /* 1815 * Release a buffer back to the appropriate queue but do not try to free 1816 * it. The buffer is expected to be used again soon. 1817 * 1818 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1819 * biodone() to requeue an async I/O on completion. It is also used when 1820 * known good buffers need to be requeued but we think we may need the data 1821 * again soon. 1822 * 1823 * XXX we should be able to leave the B_RELBUF hint set on completion. 1824 */ 1825 void 1826 bqrelse(struct buf *bp) 1827 { 1828 int qindex; 1829 1830 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1831 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1832 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1833 1834 if (BUF_LOCKRECURSED(bp)) { 1835 /* do not release to free list */ 1836 BUF_UNLOCK(bp); 1837 return; 1838 } 1839 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1840 1841 if (bp->b_flags & B_MANAGED) { 1842 if (bp->b_flags & B_REMFREE) 1843 bremfreef(bp); 1844 goto out; 1845 } 1846 1847 /* buffers with stale but valid contents */ 1848 if ((bp->b_flags & B_DELWRI) != 0 || (bp->b_vflags & (BV_BKGRDINPROG | 1849 BV_BKGRDERR)) == BV_BKGRDERR) { 1850 BO_LOCK(bp->b_bufobj); 1851 bp->b_vflags &= ~BV_BKGRDERR; 1852 BO_UNLOCK(bp->b_bufobj); 1853 qindex = QUEUE_DIRTY; 1854 } else { 1855 if ((bp->b_flags & B_DELWRI) == 0 && 1856 (bp->b_xflags & BX_VNDIRTY)) 1857 panic("bqrelse: not dirty"); 1858 qindex = QUEUE_CLEAN; 1859 } 1860 binsfree(bp, qindex); 1861 1862 out: 1863 /* unlock */ 1864 BUF_UNLOCK(bp); 1865 } 1866 1867 /* Give pages used by the bp back to the VM system (where possible) */ 1868 static void 1869 vfs_vmio_release(struct buf *bp) 1870 { 1871 vm_object_t obj; 1872 vm_page_t m; 1873 int i; 1874 1875 if ((bp->b_flags & B_UNMAPPED) == 0) { 1876 BUF_CHECK_MAPPED(bp); 1877 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages); 1878 } else 1879 BUF_CHECK_UNMAPPED(bp); 1880 obj = bp->b_bufobj->bo_object; 1881 if (obj != NULL) 1882 VM_OBJECT_WLOCK(obj); 1883 for (i = 0; i < bp->b_npages; i++) { 1884 m = bp->b_pages[i]; 1885 bp->b_pages[i] = NULL; 1886 /* 1887 * In order to keep page LRU ordering consistent, put 1888 * everything on the inactive queue. 1889 */ 1890 vm_page_lock(m); 1891 vm_page_unwire(m, PQ_INACTIVE); 1892 1893 /* 1894 * Might as well free the page if we can and it has 1895 * no valid data. We also free the page if the 1896 * buffer was used for direct I/O 1897 */ 1898 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid) { 1899 if (m->wire_count == 0 && !vm_page_busied(m)) 1900 vm_page_free(m); 1901 } else if (bp->b_flags & B_DIRECT) 1902 vm_page_try_to_free(m); 1903 vm_page_unlock(m); 1904 } 1905 if (obj != NULL) 1906 VM_OBJECT_WUNLOCK(obj); 1907 1908 if (bp->b_bufsize) { 1909 bufspacewakeup(); 1910 bp->b_bufsize = 0; 1911 } 1912 bp->b_npages = 0; 1913 bp->b_flags &= ~B_VMIO; 1914 if (bp->b_vp) 1915 brelvp(bp); 1916 } 1917 1918 /* 1919 * Check to see if a block at a particular lbn is available for a clustered 1920 * write. 1921 */ 1922 static int 1923 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 1924 { 1925 struct buf *bpa; 1926 int match; 1927 1928 match = 0; 1929 1930 /* If the buf isn't in core skip it */ 1931 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 1932 return (0); 1933 1934 /* If the buf is busy we don't want to wait for it */ 1935 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1936 return (0); 1937 1938 /* Only cluster with valid clusterable delayed write buffers */ 1939 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 1940 (B_DELWRI | B_CLUSTEROK)) 1941 goto done; 1942 1943 if (bpa->b_bufsize != size) 1944 goto done; 1945 1946 /* 1947 * Check to see if it is in the expected place on disk and that the 1948 * block has been mapped. 1949 */ 1950 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 1951 match = 1; 1952 done: 1953 BUF_UNLOCK(bpa); 1954 return (match); 1955 } 1956 1957 /* 1958 * vfs_bio_awrite: 1959 * 1960 * Implement clustered async writes for clearing out B_DELWRI buffers. 1961 * This is much better then the old way of writing only one buffer at 1962 * a time. Note that we may not be presented with the buffers in the 1963 * correct order, so we search for the cluster in both directions. 1964 */ 1965 int 1966 vfs_bio_awrite(struct buf *bp) 1967 { 1968 struct bufobj *bo; 1969 int i; 1970 int j; 1971 daddr_t lblkno = bp->b_lblkno; 1972 struct vnode *vp = bp->b_vp; 1973 int ncl; 1974 int nwritten; 1975 int size; 1976 int maxcl; 1977 int gbflags; 1978 1979 bo = &vp->v_bufobj; 1980 gbflags = (bp->b_flags & B_UNMAPPED) != 0 ? GB_UNMAPPED : 0; 1981 /* 1982 * right now we support clustered writing only to regular files. If 1983 * we find a clusterable block we could be in the middle of a cluster 1984 * rather then at the beginning. 1985 */ 1986 if ((vp->v_type == VREG) && 1987 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1988 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1989 1990 size = vp->v_mount->mnt_stat.f_iosize; 1991 maxcl = MAXPHYS / size; 1992 1993 BO_RLOCK(bo); 1994 for (i = 1; i < maxcl; i++) 1995 if (vfs_bio_clcheck(vp, size, lblkno + i, 1996 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 1997 break; 1998 1999 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 2000 if (vfs_bio_clcheck(vp, size, lblkno - j, 2001 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 2002 break; 2003 BO_RUNLOCK(bo); 2004 --j; 2005 ncl = i + j; 2006 /* 2007 * this is a possible cluster write 2008 */ 2009 if (ncl != 1) { 2010 BUF_UNLOCK(bp); 2011 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl, 2012 gbflags); 2013 return (nwritten); 2014 } 2015 } 2016 bremfree(bp); 2017 bp->b_flags |= B_ASYNC; 2018 /* 2019 * default (old) behavior, writing out only one block 2020 * 2021 * XXX returns b_bufsize instead of b_bcount for nwritten? 2022 */ 2023 nwritten = bp->b_bufsize; 2024 (void) bwrite(bp); 2025 2026 return (nwritten); 2027 } 2028 2029 static void 2030 setbufkva(struct buf *bp, vm_offset_t addr, int maxsize, int gbflags) 2031 { 2032 2033 KASSERT((bp->b_flags & (B_UNMAPPED | B_KVAALLOC)) == 0 && 2034 bp->b_kvasize == 0, ("call bfreekva(%p)", bp)); 2035 if ((gbflags & GB_UNMAPPED) == 0) { 2036 bp->b_kvabase = (caddr_t)addr; 2037 } else if ((gbflags & GB_KVAALLOC) != 0) { 2038 KASSERT((gbflags & GB_UNMAPPED) != 0, 2039 ("GB_KVAALLOC without GB_UNMAPPED")); 2040 bp->b_kvaalloc = (caddr_t)addr; 2041 bp->b_flags |= B_UNMAPPED | B_KVAALLOC; 2042 atomic_add_long(&unmapped_bufspace, bp->b_kvasize); 2043 } 2044 bp->b_kvasize = maxsize; 2045 } 2046 2047 /* 2048 * Allocate the buffer KVA and set b_kvasize. Also set b_kvabase if 2049 * needed. 2050 */ 2051 static int 2052 allocbufkva(struct buf *bp, int maxsize, int gbflags) 2053 { 2054 vm_offset_t addr; 2055 2056 bfreekva(bp); 2057 addr = 0; 2058 2059 if (vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr)) { 2060 /* 2061 * Buffer map is too fragmented. Request the caller 2062 * to defragment the map. 2063 */ 2064 atomic_add_int(&bufdefragcnt, 1); 2065 return (1); 2066 } 2067 setbufkva(bp, addr, maxsize, gbflags); 2068 atomic_add_long(&bufspace, bp->b_kvasize); 2069 return (0); 2070 } 2071 2072 /* 2073 * Ask the bufdaemon for help, or act as bufdaemon itself, when a 2074 * locked vnode is supplied. 2075 */ 2076 static void 2077 getnewbuf_bufd_help(struct vnode *vp, int gbflags, int slpflag, int slptimeo, 2078 int defrag) 2079 { 2080 struct thread *td; 2081 char *waitmsg; 2082 int error, fl, flags, norunbuf; 2083 2084 mtx_assert(&bqclean, MA_OWNED); 2085 2086 if (defrag) { 2087 flags = VFS_BIO_NEED_BUFSPACE; 2088 waitmsg = "nbufkv"; 2089 } else if (bufspace >= hibufspace) { 2090 waitmsg = "nbufbs"; 2091 flags = VFS_BIO_NEED_BUFSPACE; 2092 } else { 2093 waitmsg = "newbuf"; 2094 flags = VFS_BIO_NEED_ANY; 2095 } 2096 atomic_set_int(&needsbuffer, flags); 2097 mtx_unlock(&bqclean); 2098 2099 bd_speedup(); /* heeeelp */ 2100 if ((gbflags & GB_NOWAIT_BD) != 0) 2101 return; 2102 2103 td = curthread; 2104 rw_wlock(&nblock); 2105 while ((needsbuffer & flags) != 0) { 2106 if (vp != NULL && vp->v_type != VCHR && 2107 (td->td_pflags & TDP_BUFNEED) == 0) { 2108 rw_wunlock(&nblock); 2109 /* 2110 * getblk() is called with a vnode locked, and 2111 * some majority of the dirty buffers may as 2112 * well belong to the vnode. Flushing the 2113 * buffers there would make a progress that 2114 * cannot be achieved by the buf_daemon, that 2115 * cannot lock the vnode. 2116 */ 2117 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) | 2118 (td->td_pflags & TDP_NORUNNINGBUF); 2119 2120 /* 2121 * Play bufdaemon. The getnewbuf() function 2122 * may be called while the thread owns lock 2123 * for another dirty buffer for the same 2124 * vnode, which makes it impossible to use 2125 * VOP_FSYNC() there, due to the buffer lock 2126 * recursion. 2127 */ 2128 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF; 2129 fl = buf_flush(vp, flushbufqtarget); 2130 td->td_pflags &= norunbuf; 2131 rw_wlock(&nblock); 2132 if (fl != 0) 2133 continue; 2134 if ((needsbuffer & flags) == 0) 2135 break; 2136 } 2137 error = rw_sleep(__DEVOLATILE(void *, &needsbuffer), &nblock, 2138 (PRIBIO + 4) | slpflag, waitmsg, slptimeo); 2139 if (error != 0) 2140 break; 2141 } 2142 rw_wunlock(&nblock); 2143 } 2144 2145 static void 2146 getnewbuf_reuse_bp(struct buf *bp, int qindex) 2147 { 2148 2149 CTR6(KTR_BUF, "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d " 2150 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags, 2151 bp->b_kvasize, bp->b_bufsize, qindex); 2152 mtx_assert(&bqclean, MA_NOTOWNED); 2153 2154 /* 2155 * Note: we no longer distinguish between VMIO and non-VMIO 2156 * buffers. 2157 */ 2158 KASSERT((bp->b_flags & B_DELWRI) == 0, 2159 ("delwri buffer %p found in queue %d", bp, qindex)); 2160 2161 if (qindex == QUEUE_CLEAN) { 2162 if (bp->b_flags & B_VMIO) { 2163 bp->b_flags &= ~B_ASYNC; 2164 vfs_vmio_release(bp); 2165 } 2166 if (bp->b_vp != NULL) 2167 brelvp(bp); 2168 } 2169 2170 /* 2171 * Get the rest of the buffer freed up. b_kva* is still valid 2172 * after this operation. 2173 */ 2174 2175 if (bp->b_rcred != NOCRED) { 2176 crfree(bp->b_rcred); 2177 bp->b_rcred = NOCRED; 2178 } 2179 if (bp->b_wcred != NOCRED) { 2180 crfree(bp->b_wcred); 2181 bp->b_wcred = NOCRED; 2182 } 2183 if (!LIST_EMPTY(&bp->b_dep)) 2184 buf_deallocate(bp); 2185 if (bp->b_vflags & BV_BKGRDINPROG) 2186 panic("losing buffer 3"); 2187 KASSERT(bp->b_vp == NULL, ("bp: %p still has vnode %p. qindex: %d", 2188 bp, bp->b_vp, qindex)); 2189 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 2190 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags)); 2191 2192 if (bp->b_bufsize) 2193 allocbuf(bp, 0); 2194 2195 bp->b_flags &= B_UNMAPPED | B_KVAALLOC; 2196 bp->b_ioflags = 0; 2197 bp->b_xflags = 0; 2198 KASSERT((bp->b_flags & B_INFREECNT) == 0, 2199 ("buf %p still counted as free?", bp)); 2200 bp->b_vflags = 0; 2201 bp->b_vp = NULL; 2202 bp->b_blkno = bp->b_lblkno = 0; 2203 bp->b_offset = NOOFFSET; 2204 bp->b_iodone = 0; 2205 bp->b_error = 0; 2206 bp->b_resid = 0; 2207 bp->b_bcount = 0; 2208 bp->b_npages = 0; 2209 bp->b_dirtyoff = bp->b_dirtyend = 0; 2210 bp->b_bufobj = NULL; 2211 bp->b_pin_count = 0; 2212 bp->b_fsprivate1 = NULL; 2213 bp->b_fsprivate2 = NULL; 2214 bp->b_fsprivate3 = NULL; 2215 2216 LIST_INIT(&bp->b_dep); 2217 } 2218 2219 static int flushingbufs; 2220 2221 static struct buf * 2222 getnewbuf_scan(int maxsize, int defrag, int unmapped, int metadata) 2223 { 2224 struct buf *bp, *nbp; 2225 int nqindex, qindex, pass; 2226 2227 KASSERT(!unmapped || !defrag, ("both unmapped and defrag")); 2228 2229 pass = 1; 2230 restart: 2231 atomic_add_int(&getnewbufrestarts, 1); 2232 2233 /* 2234 * Setup for scan. If we do not have enough free buffers, 2235 * we setup a degenerate case that immediately fails. Note 2236 * that if we are specially marked process, we are allowed to 2237 * dip into our reserves. 2238 * 2239 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 2240 * for the allocation of the mapped buffer. For unmapped, the 2241 * easiest is to start with EMPTY outright. 2242 * 2243 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 2244 * However, there are a number of cases (defragging, reusing, ...) 2245 * where we cannot backup. 2246 */ 2247 nbp = NULL; 2248 mtx_lock(&bqclean); 2249 if (!defrag && unmapped) { 2250 nqindex = QUEUE_EMPTY; 2251 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 2252 } 2253 if (nbp == NULL) { 2254 nqindex = QUEUE_EMPTYKVA; 2255 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 2256 } 2257 2258 /* 2259 * If no EMPTYKVA buffers and we are either defragging or 2260 * reusing, locate a CLEAN buffer to free or reuse. If 2261 * bufspace useage is low skip this step so we can allocate a 2262 * new buffer. 2263 */ 2264 if (nbp == NULL && (defrag || bufspace >= lobufspace)) { 2265 nqindex = QUEUE_CLEAN; 2266 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2267 } 2268 2269 /* 2270 * If we could not find or were not allowed to reuse a CLEAN 2271 * buffer, check to see if it is ok to use an EMPTY buffer. 2272 * We can only use an EMPTY buffer if allocating its KVA would 2273 * not otherwise run us out of buffer space. No KVA is needed 2274 * for the unmapped allocation. 2275 */ 2276 if (nbp == NULL && defrag == 0 && (bufspace + maxsize < hibufspace || 2277 metadata)) { 2278 nqindex = QUEUE_EMPTY; 2279 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 2280 } 2281 2282 /* 2283 * All available buffers might be clean, retry ignoring the 2284 * lobufspace as the last resort. 2285 */ 2286 if (nbp == NULL && !TAILQ_EMPTY(&bufqueues[QUEUE_CLEAN])) { 2287 nqindex = QUEUE_CLEAN; 2288 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2289 } 2290 2291 /* 2292 * Run scan, possibly freeing data and/or kva mappings on the fly 2293 * depending. 2294 */ 2295 while ((bp = nbp) != NULL) { 2296 qindex = nqindex; 2297 2298 /* 2299 * Calculate next bp (we can only use it if we do not 2300 * block or do other fancy things). 2301 */ 2302 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 2303 switch (qindex) { 2304 case QUEUE_EMPTY: 2305 nqindex = QUEUE_EMPTYKVA; 2306 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 2307 if (nbp != NULL) 2308 break; 2309 /* FALLTHROUGH */ 2310 case QUEUE_EMPTYKVA: 2311 nqindex = QUEUE_CLEAN; 2312 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2313 if (nbp != NULL) 2314 break; 2315 /* FALLTHROUGH */ 2316 case QUEUE_CLEAN: 2317 if (metadata && pass == 1) { 2318 pass = 2; 2319 nqindex = QUEUE_EMPTY; 2320 nbp = TAILQ_FIRST( 2321 &bufqueues[QUEUE_EMPTY]); 2322 } 2323 /* 2324 * nbp is NULL. 2325 */ 2326 break; 2327 } 2328 } 2329 /* 2330 * If we are defragging then we need a buffer with 2331 * b_kvasize != 0. XXX this situation should no longer 2332 * occur, if defrag is non-zero the buffer's b_kvasize 2333 * should also be non-zero at this point. XXX 2334 */ 2335 if (defrag && bp->b_kvasize == 0) { 2336 printf("Warning: defrag empty buffer %p\n", bp); 2337 continue; 2338 } 2339 2340 /* 2341 * Start freeing the bp. This is somewhat involved. nbp 2342 * remains valid only for QUEUE_EMPTY[KVA] bp's. 2343 */ 2344 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2345 continue; 2346 /* 2347 * BKGRDINPROG can only be set with the buf and bufobj 2348 * locks both held. We tolerate a race to clear it here. 2349 */ 2350 if (bp->b_vflags & BV_BKGRDINPROG) { 2351 BUF_UNLOCK(bp); 2352 continue; 2353 } 2354 2355 /* 2356 * Requeue the background write buffer with error. 2357 */ 2358 if ((bp->b_vflags & BV_BKGRDERR) != 0) { 2359 bremfreel(bp); 2360 mtx_unlock(&bqclean); 2361 bqrelse(bp); 2362 continue; 2363 } 2364 2365 KASSERT(bp->b_qindex == qindex, 2366 ("getnewbuf: inconsistent queue %d bp %p", qindex, bp)); 2367 2368 bremfreel(bp); 2369 mtx_unlock(&bqclean); 2370 /* 2371 * NOTE: nbp is now entirely invalid. We can only restart 2372 * the scan from this point on. 2373 */ 2374 2375 getnewbuf_reuse_bp(bp, qindex); 2376 mtx_assert(&bqclean, MA_NOTOWNED); 2377 2378 /* 2379 * If we are defragging then free the buffer. 2380 */ 2381 if (defrag) { 2382 bp->b_flags |= B_INVAL; 2383 bfreekva(bp); 2384 brelse(bp); 2385 defrag = 0; 2386 goto restart; 2387 } 2388 2389 /* 2390 * Notify any waiters for the buffer lock about 2391 * identity change by freeing the buffer. 2392 */ 2393 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp)) { 2394 bp->b_flags |= B_INVAL; 2395 bfreekva(bp); 2396 brelse(bp); 2397 goto restart; 2398 } 2399 2400 if (metadata) 2401 break; 2402 2403 /* 2404 * If we are overcomitted then recover the buffer and its 2405 * KVM space. This occurs in rare situations when multiple 2406 * processes are blocked in getnewbuf() or allocbuf(). 2407 */ 2408 if (bufspace >= hibufspace) 2409 flushingbufs = 1; 2410 if (flushingbufs && bp->b_kvasize != 0) { 2411 bp->b_flags |= B_INVAL; 2412 bfreekva(bp); 2413 brelse(bp); 2414 goto restart; 2415 } 2416 if (bufspace < lobufspace) 2417 flushingbufs = 0; 2418 break; 2419 } 2420 return (bp); 2421 } 2422 2423 /* 2424 * getnewbuf: 2425 * 2426 * Find and initialize a new buffer header, freeing up existing buffers 2427 * in the bufqueues as necessary. The new buffer is returned locked. 2428 * 2429 * Important: B_INVAL is not set. If the caller wishes to throw the 2430 * buffer away, the caller must set B_INVAL prior to calling brelse(). 2431 * 2432 * We block if: 2433 * We have insufficient buffer headers 2434 * We have insufficient buffer space 2435 * buffer_arena is too fragmented ( space reservation fails ) 2436 * If we have to flush dirty buffers ( but we try to avoid this ) 2437 */ 2438 static struct buf * 2439 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int size, int maxsize, 2440 int gbflags) 2441 { 2442 struct buf *bp; 2443 int defrag, metadata; 2444 2445 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 2446 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 2447 if (!unmapped_buf_allowed) 2448 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC); 2449 2450 defrag = 0; 2451 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 || 2452 vp->v_type == VCHR) 2453 metadata = 1; 2454 else 2455 metadata = 0; 2456 /* 2457 * We can't afford to block since we might be holding a vnode lock, 2458 * which may prevent system daemons from running. We deal with 2459 * low-memory situations by proactively returning memory and running 2460 * async I/O rather then sync I/O. 2461 */ 2462 atomic_add_int(&getnewbufcalls, 1); 2463 atomic_subtract_int(&getnewbufrestarts, 1); 2464 restart: 2465 bp = getnewbuf_scan(maxsize, defrag, (gbflags & (GB_UNMAPPED | 2466 GB_KVAALLOC)) == GB_UNMAPPED, metadata); 2467 if (bp != NULL) 2468 defrag = 0; 2469 2470 /* 2471 * If we exhausted our list, sleep as appropriate. We may have to 2472 * wakeup various daemons and write out some dirty buffers. 2473 * 2474 * Generally we are sleeping due to insufficient buffer space. 2475 */ 2476 if (bp == NULL) { 2477 mtx_assert(&bqclean, MA_OWNED); 2478 getnewbuf_bufd_help(vp, gbflags, slpflag, slptimeo, defrag); 2479 mtx_assert(&bqclean, MA_NOTOWNED); 2480 } else if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == GB_UNMAPPED) { 2481 mtx_assert(&bqclean, MA_NOTOWNED); 2482 2483 bfreekva(bp); 2484 bp->b_flags |= B_UNMAPPED; 2485 bp->b_kvabase = bp->b_data = unmapped_buf; 2486 bp->b_kvasize = maxsize; 2487 atomic_add_long(&bufspace, bp->b_kvasize); 2488 atomic_add_long(&unmapped_bufspace, bp->b_kvasize); 2489 atomic_add_int(&bufreusecnt, 1); 2490 } else { 2491 mtx_assert(&bqclean, MA_NOTOWNED); 2492 2493 /* 2494 * We finally have a valid bp. We aren't quite out of the 2495 * woods, we still have to reserve kva space. In order 2496 * to keep fragmentation sane we only allocate kva in 2497 * BKVASIZE chunks. 2498 */ 2499 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2500 2501 if (maxsize != bp->b_kvasize || (bp->b_flags & (B_UNMAPPED | 2502 B_KVAALLOC)) == B_UNMAPPED) { 2503 if (allocbufkva(bp, maxsize, gbflags)) { 2504 defrag = 1; 2505 bp->b_flags |= B_INVAL; 2506 brelse(bp); 2507 goto restart; 2508 } 2509 atomic_add_int(&bufreusecnt, 1); 2510 } else if ((bp->b_flags & B_KVAALLOC) != 0 && 2511 (gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == 0) { 2512 /* 2513 * If the reused buffer has KVA allocated, 2514 * reassign b_kvaalloc to b_kvabase. 2515 */ 2516 bp->b_kvabase = bp->b_kvaalloc; 2517 bp->b_flags &= ~B_KVAALLOC; 2518 atomic_subtract_long(&unmapped_bufspace, 2519 bp->b_kvasize); 2520 atomic_add_int(&bufreusecnt, 1); 2521 } else if ((bp->b_flags & (B_UNMAPPED | B_KVAALLOC)) == 0 && 2522 (gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == (GB_UNMAPPED | 2523 GB_KVAALLOC)) { 2524 /* 2525 * The case of reused buffer already have KVA 2526 * mapped, but the request is for unmapped 2527 * buffer with KVA allocated. 2528 */ 2529 bp->b_kvaalloc = bp->b_kvabase; 2530 bp->b_data = bp->b_kvabase = unmapped_buf; 2531 bp->b_flags |= B_UNMAPPED | B_KVAALLOC; 2532 atomic_add_long(&unmapped_bufspace, 2533 bp->b_kvasize); 2534 atomic_add_int(&bufreusecnt, 1); 2535 } 2536 if ((gbflags & GB_UNMAPPED) == 0) { 2537 bp->b_saveaddr = bp->b_kvabase; 2538 bp->b_data = bp->b_saveaddr; 2539 bp->b_flags &= ~B_UNMAPPED; 2540 BUF_CHECK_MAPPED(bp); 2541 } 2542 } 2543 return (bp); 2544 } 2545 2546 /* 2547 * buf_daemon: 2548 * 2549 * buffer flushing daemon. Buffers are normally flushed by the 2550 * update daemon but if it cannot keep up this process starts to 2551 * take the load in an attempt to prevent getnewbuf() from blocking. 2552 */ 2553 2554 static struct kproc_desc buf_kp = { 2555 "bufdaemon", 2556 buf_daemon, 2557 &bufdaemonproc 2558 }; 2559 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 2560 2561 static int 2562 buf_flush(struct vnode *vp, int target) 2563 { 2564 int flushed; 2565 2566 flushed = flushbufqueues(vp, target, 0); 2567 if (flushed == 0) { 2568 /* 2569 * Could not find any buffers without rollback 2570 * dependencies, so just write the first one 2571 * in the hopes of eventually making progress. 2572 */ 2573 if (vp != NULL && target > 2) 2574 target /= 2; 2575 flushbufqueues(vp, target, 1); 2576 } 2577 return (flushed); 2578 } 2579 2580 static void 2581 buf_daemon() 2582 { 2583 int lodirty; 2584 2585 /* 2586 * This process needs to be suspended prior to shutdown sync. 2587 */ 2588 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2589 SHUTDOWN_PRI_LAST); 2590 2591 /* 2592 * This process is allowed to take the buffer cache to the limit 2593 */ 2594 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 2595 mtx_lock(&bdlock); 2596 for (;;) { 2597 bd_request = 0; 2598 mtx_unlock(&bdlock); 2599 2600 kproc_suspend_check(bufdaemonproc); 2601 lodirty = lodirtybuffers; 2602 if (bd_speedupreq) { 2603 lodirty = numdirtybuffers / 2; 2604 bd_speedupreq = 0; 2605 } 2606 /* 2607 * Do the flush. Limit the amount of in-transit I/O we 2608 * allow to build up, otherwise we would completely saturate 2609 * the I/O system. 2610 */ 2611 while (numdirtybuffers > lodirty) { 2612 if (buf_flush(NULL, numdirtybuffers - lodirty) == 0) 2613 break; 2614 kern_yield(PRI_USER); 2615 } 2616 2617 /* 2618 * Only clear bd_request if we have reached our low water 2619 * mark. The buf_daemon normally waits 1 second and 2620 * then incrementally flushes any dirty buffers that have 2621 * built up, within reason. 2622 * 2623 * If we were unable to hit our low water mark and couldn't 2624 * find any flushable buffers, we sleep for a short period 2625 * to avoid endless loops on unlockable buffers. 2626 */ 2627 mtx_lock(&bdlock); 2628 if (numdirtybuffers <= lodirtybuffers) { 2629 /* 2630 * We reached our low water mark, reset the 2631 * request and sleep until we are needed again. 2632 * The sleep is just so the suspend code works. 2633 */ 2634 bd_request = 0; 2635 /* 2636 * Do an extra wakeup in case dirty threshold 2637 * changed via sysctl and the explicit transition 2638 * out of shortfall was missed. 2639 */ 2640 bdirtywakeup(); 2641 if (runningbufspace <= lorunningspace) 2642 runningwakeup(); 2643 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 2644 } else { 2645 /* 2646 * We couldn't find any flushable dirty buffers but 2647 * still have too many dirty buffers, we 2648 * have to sleep and try again. (rare) 2649 */ 2650 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 2651 } 2652 } 2653 } 2654 2655 /* 2656 * flushbufqueues: 2657 * 2658 * Try to flush a buffer in the dirty queue. We must be careful to 2659 * free up B_INVAL buffers instead of write them, which NFS is 2660 * particularly sensitive to. 2661 */ 2662 static int flushwithdeps = 0; 2663 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 2664 0, "Number of buffers flushed with dependecies that require rollbacks"); 2665 2666 static int 2667 flushbufqueues(struct vnode *lvp, int target, int flushdeps) 2668 { 2669 struct buf *sentinel; 2670 struct vnode *vp; 2671 struct mount *mp; 2672 struct buf *bp; 2673 int hasdeps; 2674 int flushed; 2675 int queue; 2676 int error; 2677 bool unlock; 2678 2679 flushed = 0; 2680 queue = QUEUE_DIRTY; 2681 bp = NULL; 2682 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 2683 sentinel->b_qindex = QUEUE_SENTINEL; 2684 mtx_lock(&bqdirty); 2685 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist); 2686 mtx_unlock(&bqdirty); 2687 while (flushed != target) { 2688 maybe_yield(); 2689 mtx_lock(&bqdirty); 2690 bp = TAILQ_NEXT(sentinel, b_freelist); 2691 if (bp != NULL) { 2692 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2693 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel, 2694 b_freelist); 2695 } else { 2696 mtx_unlock(&bqdirty); 2697 break; 2698 } 2699 /* 2700 * Skip sentinels inserted by other invocations of the 2701 * flushbufqueues(), taking care to not reorder them. 2702 * 2703 * Only flush the buffers that belong to the 2704 * vnode locked by the curthread. 2705 */ 2706 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL && 2707 bp->b_vp != lvp)) { 2708 mtx_unlock(&bqdirty); 2709 continue; 2710 } 2711 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL); 2712 mtx_unlock(&bqdirty); 2713 if (error != 0) 2714 continue; 2715 if (bp->b_pin_count > 0) { 2716 BUF_UNLOCK(bp); 2717 continue; 2718 } 2719 /* 2720 * BKGRDINPROG can only be set with the buf and bufobj 2721 * locks both held. We tolerate a race to clear it here. 2722 */ 2723 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 2724 (bp->b_flags & B_DELWRI) == 0) { 2725 BUF_UNLOCK(bp); 2726 continue; 2727 } 2728 if (bp->b_flags & B_INVAL) { 2729 bremfreef(bp); 2730 brelse(bp); 2731 flushed++; 2732 continue; 2733 } 2734 2735 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 2736 if (flushdeps == 0) { 2737 BUF_UNLOCK(bp); 2738 continue; 2739 } 2740 hasdeps = 1; 2741 } else 2742 hasdeps = 0; 2743 /* 2744 * We must hold the lock on a vnode before writing 2745 * one of its buffers. Otherwise we may confuse, or 2746 * in the case of a snapshot vnode, deadlock the 2747 * system. 2748 * 2749 * The lock order here is the reverse of the normal 2750 * of vnode followed by buf lock. This is ok because 2751 * the NOWAIT will prevent deadlock. 2752 */ 2753 vp = bp->b_vp; 2754 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 2755 BUF_UNLOCK(bp); 2756 continue; 2757 } 2758 if (lvp == NULL) { 2759 unlock = true; 2760 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT); 2761 } else { 2762 ASSERT_VOP_LOCKED(vp, "getbuf"); 2763 unlock = false; 2764 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 : 2765 vn_lock(vp, LK_TRYUPGRADE); 2766 } 2767 if (error == 0) { 2768 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 2769 bp, bp->b_vp, bp->b_flags); 2770 if (curproc == bufdaemonproc) { 2771 vfs_bio_awrite(bp); 2772 } else { 2773 bremfree(bp); 2774 bwrite(bp); 2775 notbufdflushes++; 2776 } 2777 vn_finished_write(mp); 2778 if (unlock) 2779 VOP_UNLOCK(vp, 0); 2780 flushwithdeps += hasdeps; 2781 flushed++; 2782 2783 /* 2784 * Sleeping on runningbufspace while holding 2785 * vnode lock leads to deadlock. 2786 */ 2787 if (curproc == bufdaemonproc && 2788 runningbufspace > hirunningspace) 2789 waitrunningbufspace(); 2790 continue; 2791 } 2792 vn_finished_write(mp); 2793 BUF_UNLOCK(bp); 2794 } 2795 mtx_lock(&bqdirty); 2796 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2797 mtx_unlock(&bqdirty); 2798 free(sentinel, M_TEMP); 2799 return (flushed); 2800 } 2801 2802 /* 2803 * Check to see if a block is currently memory resident. 2804 */ 2805 struct buf * 2806 incore(struct bufobj *bo, daddr_t blkno) 2807 { 2808 struct buf *bp; 2809 2810 BO_RLOCK(bo); 2811 bp = gbincore(bo, blkno); 2812 BO_RUNLOCK(bo); 2813 return (bp); 2814 } 2815 2816 /* 2817 * Returns true if no I/O is needed to access the 2818 * associated VM object. This is like incore except 2819 * it also hunts around in the VM system for the data. 2820 */ 2821 2822 static int 2823 inmem(struct vnode * vp, daddr_t blkno) 2824 { 2825 vm_object_t obj; 2826 vm_offset_t toff, tinc, size; 2827 vm_page_t m; 2828 vm_ooffset_t off; 2829 2830 ASSERT_VOP_LOCKED(vp, "inmem"); 2831 2832 if (incore(&vp->v_bufobj, blkno)) 2833 return 1; 2834 if (vp->v_mount == NULL) 2835 return 0; 2836 obj = vp->v_object; 2837 if (obj == NULL) 2838 return (0); 2839 2840 size = PAGE_SIZE; 2841 if (size > vp->v_mount->mnt_stat.f_iosize) 2842 size = vp->v_mount->mnt_stat.f_iosize; 2843 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2844 2845 VM_OBJECT_RLOCK(obj); 2846 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2847 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2848 if (!m) 2849 goto notinmem; 2850 tinc = size; 2851 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2852 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2853 if (vm_page_is_valid(m, 2854 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2855 goto notinmem; 2856 } 2857 VM_OBJECT_RUNLOCK(obj); 2858 return 1; 2859 2860 notinmem: 2861 VM_OBJECT_RUNLOCK(obj); 2862 return (0); 2863 } 2864 2865 /* 2866 * Set the dirty range for a buffer based on the status of the dirty 2867 * bits in the pages comprising the buffer. The range is limited 2868 * to the size of the buffer. 2869 * 2870 * Tell the VM system that the pages associated with this buffer 2871 * are clean. This is used for delayed writes where the data is 2872 * going to go to disk eventually without additional VM intevention. 2873 * 2874 * Note that while we only really need to clean through to b_bcount, we 2875 * just go ahead and clean through to b_bufsize. 2876 */ 2877 static void 2878 vfs_clean_pages_dirty_buf(struct buf *bp) 2879 { 2880 vm_ooffset_t foff, noff, eoff; 2881 vm_page_t m; 2882 int i; 2883 2884 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 2885 return; 2886 2887 foff = bp->b_offset; 2888 KASSERT(bp->b_offset != NOOFFSET, 2889 ("vfs_clean_pages_dirty_buf: no buffer offset")); 2890 2891 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 2892 vfs_drain_busy_pages(bp); 2893 vfs_setdirty_locked_object(bp); 2894 for (i = 0; i < bp->b_npages; i++) { 2895 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2896 eoff = noff; 2897 if (eoff > bp->b_offset + bp->b_bufsize) 2898 eoff = bp->b_offset + bp->b_bufsize; 2899 m = bp->b_pages[i]; 2900 vfs_page_set_validclean(bp, foff, m); 2901 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 2902 foff = noff; 2903 } 2904 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 2905 } 2906 2907 static void 2908 vfs_setdirty_locked_object(struct buf *bp) 2909 { 2910 vm_object_t object; 2911 int i; 2912 2913 object = bp->b_bufobj->bo_object; 2914 VM_OBJECT_ASSERT_WLOCKED(object); 2915 2916 /* 2917 * We qualify the scan for modified pages on whether the 2918 * object has been flushed yet. 2919 */ 2920 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) { 2921 vm_offset_t boffset; 2922 vm_offset_t eoffset; 2923 2924 /* 2925 * test the pages to see if they have been modified directly 2926 * by users through the VM system. 2927 */ 2928 for (i = 0; i < bp->b_npages; i++) 2929 vm_page_test_dirty(bp->b_pages[i]); 2930 2931 /* 2932 * Calculate the encompassing dirty range, boffset and eoffset, 2933 * (eoffset - boffset) bytes. 2934 */ 2935 2936 for (i = 0; i < bp->b_npages; i++) { 2937 if (bp->b_pages[i]->dirty) 2938 break; 2939 } 2940 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2941 2942 for (i = bp->b_npages - 1; i >= 0; --i) { 2943 if (bp->b_pages[i]->dirty) { 2944 break; 2945 } 2946 } 2947 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2948 2949 /* 2950 * Fit it to the buffer. 2951 */ 2952 2953 if (eoffset > bp->b_bcount) 2954 eoffset = bp->b_bcount; 2955 2956 /* 2957 * If we have a good dirty range, merge with the existing 2958 * dirty range. 2959 */ 2960 2961 if (boffset < eoffset) { 2962 if (bp->b_dirtyoff > boffset) 2963 bp->b_dirtyoff = boffset; 2964 if (bp->b_dirtyend < eoffset) 2965 bp->b_dirtyend = eoffset; 2966 } 2967 } 2968 } 2969 2970 /* 2971 * Allocate the KVA mapping for an existing buffer. It handles the 2972 * cases of both B_UNMAPPED buffer, and buffer with the preallocated 2973 * KVA which is not mapped (B_KVAALLOC). 2974 */ 2975 static void 2976 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags) 2977 { 2978 struct buf *scratch_bp; 2979 int bsize, maxsize, need_mapping, need_kva; 2980 off_t offset; 2981 2982 need_mapping = (bp->b_flags & B_UNMAPPED) != 0 && 2983 (gbflags & GB_UNMAPPED) == 0; 2984 need_kva = (bp->b_flags & (B_KVAALLOC | B_UNMAPPED)) == B_UNMAPPED && 2985 (gbflags & GB_KVAALLOC) != 0; 2986 if (!need_mapping && !need_kva) 2987 return; 2988 2989 BUF_CHECK_UNMAPPED(bp); 2990 2991 if (need_mapping && (bp->b_flags & B_KVAALLOC) != 0) { 2992 /* 2993 * Buffer is not mapped, but the KVA was already 2994 * reserved at the time of the instantiation. Use the 2995 * allocated space. 2996 */ 2997 bp->b_flags &= ~B_KVAALLOC; 2998 KASSERT(bp->b_kvaalloc != 0, ("kvaalloc == 0")); 2999 bp->b_kvabase = bp->b_kvaalloc; 3000 atomic_subtract_long(&unmapped_bufspace, bp->b_kvasize); 3001 goto has_addr; 3002 } 3003 3004 /* 3005 * Calculate the amount of the address space we would reserve 3006 * if the buffer was mapped. 3007 */ 3008 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize; 3009 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3010 offset = blkno * bsize; 3011 maxsize = size + (offset & PAGE_MASK); 3012 maxsize = imax(maxsize, bsize); 3013 3014 mapping_loop: 3015 if (allocbufkva(bp, maxsize, gbflags)) { 3016 /* 3017 * Request defragmentation. getnewbuf() returns us the 3018 * allocated space by the scratch buffer KVA. 3019 */ 3020 scratch_bp = getnewbuf(bp->b_vp, 0, 0, size, maxsize, gbflags | 3021 (GB_UNMAPPED | GB_KVAALLOC)); 3022 if (scratch_bp == NULL) { 3023 if ((gbflags & GB_NOWAIT_BD) != 0) { 3024 /* 3025 * XXXKIB: defragmentation cannot 3026 * succeed, not sure what else to do. 3027 */ 3028 panic("GB_NOWAIT_BD and B_UNMAPPED %p", bp); 3029 } 3030 atomic_add_int(&mappingrestarts, 1); 3031 goto mapping_loop; 3032 } 3033 KASSERT((scratch_bp->b_flags & B_KVAALLOC) != 0, 3034 ("scratch bp !B_KVAALLOC %p", scratch_bp)); 3035 setbufkva(bp, (vm_offset_t)scratch_bp->b_kvaalloc, 3036 scratch_bp->b_kvasize, gbflags); 3037 3038 /* Get rid of the scratch buffer. */ 3039 scratch_bp->b_kvasize = 0; 3040 scratch_bp->b_flags |= B_INVAL; 3041 scratch_bp->b_flags &= ~(B_UNMAPPED | B_KVAALLOC); 3042 brelse(scratch_bp); 3043 } 3044 if (!need_mapping) 3045 return; 3046 3047 has_addr: 3048 bp->b_saveaddr = bp->b_kvabase; 3049 bp->b_data = bp->b_saveaddr; /* b_offset is handled by bpmap_qenter */ 3050 bp->b_flags &= ~B_UNMAPPED; 3051 BUF_CHECK_MAPPED(bp); 3052 bpmap_qenter(bp); 3053 } 3054 3055 /* 3056 * getblk: 3057 * 3058 * Get a block given a specified block and offset into a file/device. 3059 * The buffers B_DONE bit will be cleared on return, making it almost 3060 * ready for an I/O initiation. B_INVAL may or may not be set on 3061 * return. The caller should clear B_INVAL prior to initiating a 3062 * READ. 3063 * 3064 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 3065 * an existing buffer. 3066 * 3067 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 3068 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 3069 * and then cleared based on the backing VM. If the previous buffer is 3070 * non-0-sized but invalid, B_CACHE will be cleared. 3071 * 3072 * If getblk() must create a new buffer, the new buffer is returned with 3073 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 3074 * case it is returned with B_INVAL clear and B_CACHE set based on the 3075 * backing VM. 3076 * 3077 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 3078 * B_CACHE bit is clear. 3079 * 3080 * What this means, basically, is that the caller should use B_CACHE to 3081 * determine whether the buffer is fully valid or not and should clear 3082 * B_INVAL prior to issuing a read. If the caller intends to validate 3083 * the buffer by loading its data area with something, the caller needs 3084 * to clear B_INVAL. If the caller does this without issuing an I/O, 3085 * the caller should set B_CACHE ( as an optimization ), else the caller 3086 * should issue the I/O and biodone() will set B_CACHE if the I/O was 3087 * a write attempt or if it was a successfull read. If the caller 3088 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 3089 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 3090 */ 3091 struct buf * 3092 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3093 int flags) 3094 { 3095 struct buf *bp; 3096 struct bufobj *bo; 3097 int bsize, error, maxsize, vmio; 3098 off_t offset; 3099 3100 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 3101 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3102 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3103 ASSERT_VOP_LOCKED(vp, "getblk"); 3104 if (size > MAXBCACHEBUF) 3105 panic("getblk: size(%d) > MAXBCACHEBUF(%d)\n", size, 3106 MAXBCACHEBUF); 3107 if (!unmapped_buf_allowed) 3108 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3109 3110 bo = &vp->v_bufobj; 3111 loop: 3112 BO_RLOCK(bo); 3113 bp = gbincore(bo, blkno); 3114 if (bp != NULL) { 3115 int lockflags; 3116 /* 3117 * Buffer is in-core. If the buffer is not busy nor managed, 3118 * it must be on a queue. 3119 */ 3120 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 3121 3122 if (flags & GB_LOCK_NOWAIT) 3123 lockflags |= LK_NOWAIT; 3124 3125 error = BUF_TIMELOCK(bp, lockflags, 3126 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo); 3127 3128 /* 3129 * If we slept and got the lock we have to restart in case 3130 * the buffer changed identities. 3131 */ 3132 if (error == ENOLCK) 3133 goto loop; 3134 /* We timed out or were interrupted. */ 3135 else if (error) 3136 return (NULL); 3137 /* If recursed, assume caller knows the rules. */ 3138 else if (BUF_LOCKRECURSED(bp)) 3139 goto end; 3140 3141 /* 3142 * The buffer is locked. B_CACHE is cleared if the buffer is 3143 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 3144 * and for a VMIO buffer B_CACHE is adjusted according to the 3145 * backing VM cache. 3146 */ 3147 if (bp->b_flags & B_INVAL) 3148 bp->b_flags &= ~B_CACHE; 3149 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 3150 bp->b_flags |= B_CACHE; 3151 if (bp->b_flags & B_MANAGED) 3152 MPASS(bp->b_qindex == QUEUE_NONE); 3153 else 3154 bremfree(bp); 3155 3156 /* 3157 * check for size inconsistencies for non-VMIO case. 3158 */ 3159 if (bp->b_bcount != size) { 3160 if ((bp->b_flags & B_VMIO) == 0 || 3161 (size > bp->b_kvasize)) { 3162 if (bp->b_flags & B_DELWRI) { 3163 /* 3164 * If buffer is pinned and caller does 3165 * not want sleep waiting for it to be 3166 * unpinned, bail out 3167 * */ 3168 if (bp->b_pin_count > 0) { 3169 if (flags & GB_LOCK_NOWAIT) { 3170 bqrelse(bp); 3171 return (NULL); 3172 } else { 3173 bunpin_wait(bp); 3174 } 3175 } 3176 bp->b_flags |= B_NOCACHE; 3177 bwrite(bp); 3178 } else { 3179 if (LIST_EMPTY(&bp->b_dep)) { 3180 bp->b_flags |= B_RELBUF; 3181 brelse(bp); 3182 } else { 3183 bp->b_flags |= B_NOCACHE; 3184 bwrite(bp); 3185 } 3186 } 3187 goto loop; 3188 } 3189 } 3190 3191 /* 3192 * Handle the case of unmapped buffer which should 3193 * become mapped, or the buffer for which KVA 3194 * reservation is requested. 3195 */ 3196 bp_unmapped_get_kva(bp, blkno, size, flags); 3197 3198 /* 3199 * If the size is inconsistant in the VMIO case, we can resize 3200 * the buffer. This might lead to B_CACHE getting set or 3201 * cleared. If the size has not changed, B_CACHE remains 3202 * unchanged from its previous state. 3203 */ 3204 if (bp->b_bcount != size) 3205 allocbuf(bp, size); 3206 3207 KASSERT(bp->b_offset != NOOFFSET, 3208 ("getblk: no buffer offset")); 3209 3210 /* 3211 * A buffer with B_DELWRI set and B_CACHE clear must 3212 * be committed before we can return the buffer in 3213 * order to prevent the caller from issuing a read 3214 * ( due to B_CACHE not being set ) and overwriting 3215 * it. 3216 * 3217 * Most callers, including NFS and FFS, need this to 3218 * operate properly either because they assume they 3219 * can issue a read if B_CACHE is not set, or because 3220 * ( for example ) an uncached B_DELWRI might loop due 3221 * to softupdates re-dirtying the buffer. In the latter 3222 * case, B_CACHE is set after the first write completes, 3223 * preventing further loops. 3224 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 3225 * above while extending the buffer, we cannot allow the 3226 * buffer to remain with B_CACHE set after the write 3227 * completes or it will represent a corrupt state. To 3228 * deal with this we set B_NOCACHE to scrap the buffer 3229 * after the write. 3230 * 3231 * We might be able to do something fancy, like setting 3232 * B_CACHE in bwrite() except if B_DELWRI is already set, 3233 * so the below call doesn't set B_CACHE, but that gets real 3234 * confusing. This is much easier. 3235 */ 3236 3237 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 3238 bp->b_flags |= B_NOCACHE; 3239 bwrite(bp); 3240 goto loop; 3241 } 3242 bp->b_flags &= ~B_DONE; 3243 } else { 3244 /* 3245 * Buffer is not in-core, create new buffer. The buffer 3246 * returned by getnewbuf() is locked. Note that the returned 3247 * buffer is also considered valid (not marked B_INVAL). 3248 */ 3249 BO_RUNLOCK(bo); 3250 /* 3251 * If the user does not want us to create the buffer, bail out 3252 * here. 3253 */ 3254 if (flags & GB_NOCREAT) 3255 return NULL; 3256 if (numfreebuffers == 0 && TD_IS_IDLETHREAD(curthread)) 3257 return NULL; 3258 3259 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize; 3260 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3261 offset = blkno * bsize; 3262 vmio = vp->v_object != NULL; 3263 if (vmio) { 3264 maxsize = size + (offset & PAGE_MASK); 3265 } else { 3266 maxsize = size; 3267 /* Do not allow non-VMIO notmapped buffers. */ 3268 flags &= ~GB_UNMAPPED; 3269 } 3270 maxsize = imax(maxsize, bsize); 3271 3272 bp = getnewbuf(vp, slpflag, slptimeo, size, maxsize, flags); 3273 if (bp == NULL) { 3274 if (slpflag || slptimeo) 3275 return NULL; 3276 goto loop; 3277 } 3278 3279 /* 3280 * This code is used to make sure that a buffer is not 3281 * created while the getnewbuf routine is blocked. 3282 * This can be a problem whether the vnode is locked or not. 3283 * If the buffer is created out from under us, we have to 3284 * throw away the one we just created. 3285 * 3286 * Note: this must occur before we associate the buffer 3287 * with the vp especially considering limitations in 3288 * the splay tree implementation when dealing with duplicate 3289 * lblkno's. 3290 */ 3291 BO_LOCK(bo); 3292 if (gbincore(bo, blkno)) { 3293 BO_UNLOCK(bo); 3294 bp->b_flags |= B_INVAL; 3295 brelse(bp); 3296 goto loop; 3297 } 3298 3299 /* 3300 * Insert the buffer into the hash, so that it can 3301 * be found by incore. 3302 */ 3303 bp->b_blkno = bp->b_lblkno = blkno; 3304 bp->b_offset = offset; 3305 bgetvp(vp, bp); 3306 BO_UNLOCK(bo); 3307 3308 /* 3309 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 3310 * buffer size starts out as 0, B_CACHE will be set by 3311 * allocbuf() for the VMIO case prior to it testing the 3312 * backing store for validity. 3313 */ 3314 3315 if (vmio) { 3316 bp->b_flags |= B_VMIO; 3317 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 3318 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 3319 bp, vp->v_object, bp->b_bufobj->bo_object)); 3320 } else { 3321 bp->b_flags &= ~B_VMIO; 3322 KASSERT(bp->b_bufobj->bo_object == NULL, 3323 ("ARGH! has b_bufobj->bo_object %p %p\n", 3324 bp, bp->b_bufobj->bo_object)); 3325 BUF_CHECK_MAPPED(bp); 3326 } 3327 3328 allocbuf(bp, size); 3329 bp->b_flags &= ~B_DONE; 3330 } 3331 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 3332 BUF_ASSERT_HELD(bp); 3333 end: 3334 KASSERT(bp->b_bufobj == bo, 3335 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 3336 return (bp); 3337 } 3338 3339 /* 3340 * Get an empty, disassociated buffer of given size. The buffer is initially 3341 * set to B_INVAL. 3342 */ 3343 struct buf * 3344 geteblk(int size, int flags) 3345 { 3346 struct buf *bp; 3347 int maxsize; 3348 3349 maxsize = (size + BKVAMASK) & ~BKVAMASK; 3350 while ((bp = getnewbuf(NULL, 0, 0, size, maxsize, flags)) == NULL) { 3351 if ((flags & GB_NOWAIT_BD) && 3352 (curthread->td_pflags & TDP_BUFNEED) != 0) 3353 return (NULL); 3354 } 3355 allocbuf(bp, size); 3356 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 3357 BUF_ASSERT_HELD(bp); 3358 return (bp); 3359 } 3360 3361 3362 /* 3363 * This code constitutes the buffer memory from either anonymous system 3364 * memory (in the case of non-VMIO operations) or from an associated 3365 * VM object (in the case of VMIO operations). This code is able to 3366 * resize a buffer up or down. 3367 * 3368 * Note that this code is tricky, and has many complications to resolve 3369 * deadlock or inconsistant data situations. Tread lightly!!! 3370 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 3371 * the caller. Calling this code willy nilly can result in the loss of data. 3372 * 3373 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 3374 * B_CACHE for the non-VMIO case. 3375 */ 3376 3377 int 3378 allocbuf(struct buf *bp, int size) 3379 { 3380 int newbsize, mbsize; 3381 int i; 3382 3383 BUF_ASSERT_HELD(bp); 3384 3385 if (bp->b_kvasize < size) 3386 panic("allocbuf: buffer too small"); 3387 3388 if ((bp->b_flags & B_VMIO) == 0) { 3389 caddr_t origbuf; 3390 int origbufsize; 3391 /* 3392 * Just get anonymous memory from the kernel. Don't 3393 * mess with B_CACHE. 3394 */ 3395 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3396 if (bp->b_flags & B_MALLOC) 3397 newbsize = mbsize; 3398 else 3399 newbsize = round_page(size); 3400 3401 if (newbsize < bp->b_bufsize) { 3402 /* 3403 * malloced buffers are not shrunk 3404 */ 3405 if (bp->b_flags & B_MALLOC) { 3406 if (newbsize) { 3407 bp->b_bcount = size; 3408 } else { 3409 free(bp->b_data, M_BIOBUF); 3410 if (bp->b_bufsize) { 3411 atomic_subtract_long( 3412 &bufmallocspace, 3413 bp->b_bufsize); 3414 bufspacewakeup(); 3415 bp->b_bufsize = 0; 3416 } 3417 bp->b_saveaddr = bp->b_kvabase; 3418 bp->b_data = bp->b_saveaddr; 3419 bp->b_bcount = 0; 3420 bp->b_flags &= ~B_MALLOC; 3421 } 3422 return 1; 3423 } 3424 vm_hold_free_pages(bp, newbsize); 3425 } else if (newbsize > bp->b_bufsize) { 3426 /* 3427 * We only use malloced memory on the first allocation. 3428 * and revert to page-allocated memory when the buffer 3429 * grows. 3430 */ 3431 /* 3432 * There is a potential smp race here that could lead 3433 * to bufmallocspace slightly passing the max. It 3434 * is probably extremely rare and not worth worrying 3435 * over. 3436 */ 3437 if ( (bufmallocspace < maxbufmallocspace) && 3438 (bp->b_bufsize == 0) && 3439 (mbsize <= PAGE_SIZE/2)) { 3440 3441 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 3442 bp->b_bufsize = mbsize; 3443 bp->b_bcount = size; 3444 bp->b_flags |= B_MALLOC; 3445 atomic_add_long(&bufmallocspace, mbsize); 3446 return 1; 3447 } 3448 origbuf = NULL; 3449 origbufsize = 0; 3450 /* 3451 * If the buffer is growing on its other-than-first allocation, 3452 * then we revert to the page-allocation scheme. 3453 */ 3454 if (bp->b_flags & B_MALLOC) { 3455 origbuf = bp->b_data; 3456 origbufsize = bp->b_bufsize; 3457 bp->b_data = bp->b_kvabase; 3458 if (bp->b_bufsize) { 3459 atomic_subtract_long(&bufmallocspace, 3460 bp->b_bufsize); 3461 bufspacewakeup(); 3462 bp->b_bufsize = 0; 3463 } 3464 bp->b_flags &= ~B_MALLOC; 3465 newbsize = round_page(newbsize); 3466 } 3467 vm_hold_load_pages( 3468 bp, 3469 (vm_offset_t) bp->b_data + bp->b_bufsize, 3470 (vm_offset_t) bp->b_data + newbsize); 3471 if (origbuf) { 3472 bcopy(origbuf, bp->b_data, origbufsize); 3473 free(origbuf, M_BIOBUF); 3474 } 3475 } 3476 } else { 3477 int desiredpages; 3478 3479 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3480 desiredpages = (size == 0) ? 0 : 3481 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 3482 3483 if (bp->b_flags & B_MALLOC) 3484 panic("allocbuf: VMIO buffer can't be malloced"); 3485 /* 3486 * Set B_CACHE initially if buffer is 0 length or will become 3487 * 0-length. 3488 */ 3489 if (size == 0 || bp->b_bufsize == 0) 3490 bp->b_flags |= B_CACHE; 3491 3492 if (newbsize < bp->b_bufsize) { 3493 /* 3494 * DEV_BSIZE aligned new buffer size is less then the 3495 * DEV_BSIZE aligned existing buffer size. Figure out 3496 * if we have to remove any pages. 3497 */ 3498 if (desiredpages < bp->b_npages) { 3499 vm_page_t m; 3500 3501 if ((bp->b_flags & B_UNMAPPED) == 0) { 3502 BUF_CHECK_MAPPED(bp); 3503 pmap_qremove((vm_offset_t)trunc_page( 3504 (vm_offset_t)bp->b_data) + 3505 (desiredpages << PAGE_SHIFT), 3506 (bp->b_npages - desiredpages)); 3507 } else 3508 BUF_CHECK_UNMAPPED(bp); 3509 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 3510 for (i = desiredpages; i < bp->b_npages; i++) { 3511 /* 3512 * the page is not freed here -- it 3513 * is the responsibility of 3514 * vnode_pager_setsize 3515 */ 3516 m = bp->b_pages[i]; 3517 KASSERT(m != bogus_page, 3518 ("allocbuf: bogus page found")); 3519 while (vm_page_sleep_if_busy(m, 3520 "biodep")) 3521 continue; 3522 3523 bp->b_pages[i] = NULL; 3524 vm_page_lock(m); 3525 vm_page_unwire(m, PQ_INACTIVE); 3526 vm_page_unlock(m); 3527 } 3528 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 3529 bp->b_npages = desiredpages; 3530 } 3531 } else if (size > bp->b_bcount) { 3532 /* 3533 * We are growing the buffer, possibly in a 3534 * byte-granular fashion. 3535 */ 3536 vm_object_t obj; 3537 vm_offset_t toff; 3538 vm_offset_t tinc; 3539 3540 /* 3541 * Step 1, bring in the VM pages from the object, 3542 * allocating them if necessary. We must clear 3543 * B_CACHE if these pages are not valid for the 3544 * range covered by the buffer. 3545 */ 3546 3547 obj = bp->b_bufobj->bo_object; 3548 3549 VM_OBJECT_WLOCK(obj); 3550 while (bp->b_npages < desiredpages) { 3551 vm_page_t m; 3552 3553 /* 3554 * We must allocate system pages since blocking 3555 * here could interfere with paging I/O, no 3556 * matter which process we are. 3557 * 3558 * Only exclusive busy can be tested here. 3559 * Blocking on shared busy might lead to 3560 * deadlocks once allocbuf() is called after 3561 * pages are vfs_busy_pages(). 3562 */ 3563 m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) + 3564 bp->b_npages, VM_ALLOC_NOBUSY | 3565 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED | 3566 VM_ALLOC_IGN_SBUSY | 3567 VM_ALLOC_COUNT(desiredpages - bp->b_npages)); 3568 if (m->valid == 0) 3569 bp->b_flags &= ~B_CACHE; 3570 bp->b_pages[bp->b_npages] = m; 3571 ++bp->b_npages; 3572 } 3573 3574 /* 3575 * Step 2. We've loaded the pages into the buffer, 3576 * we have to figure out if we can still have B_CACHE 3577 * set. Note that B_CACHE is set according to the 3578 * byte-granular range ( bcount and size ), new the 3579 * aligned range ( newbsize ). 3580 * 3581 * The VM test is against m->valid, which is DEV_BSIZE 3582 * aligned. Needless to say, the validity of the data 3583 * needs to also be DEV_BSIZE aligned. Note that this 3584 * fails with NFS if the server or some other client 3585 * extends the file's EOF. If our buffer is resized, 3586 * B_CACHE may remain set! XXX 3587 */ 3588 3589 toff = bp->b_bcount; 3590 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 3591 3592 while ((bp->b_flags & B_CACHE) && toff < size) { 3593 vm_pindex_t pi; 3594 3595 if (tinc > (size - toff)) 3596 tinc = size - toff; 3597 3598 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 3599 PAGE_SHIFT; 3600 3601 vfs_buf_test_cache( 3602 bp, 3603 bp->b_offset, 3604 toff, 3605 tinc, 3606 bp->b_pages[pi] 3607 ); 3608 toff += tinc; 3609 tinc = PAGE_SIZE; 3610 } 3611 VM_OBJECT_WUNLOCK(obj); 3612 3613 /* 3614 * Step 3, fixup the KVM pmap. 3615 */ 3616 if ((bp->b_flags & B_UNMAPPED) == 0) 3617 bpmap_qenter(bp); 3618 else 3619 BUF_CHECK_UNMAPPED(bp); 3620 } 3621 } 3622 if (newbsize < bp->b_bufsize) 3623 bufspacewakeup(); 3624 bp->b_bufsize = newbsize; /* actual buffer allocation */ 3625 bp->b_bcount = size; /* requested buffer size */ 3626 return 1; 3627 } 3628 3629 extern int inflight_transient_maps; 3630 3631 void 3632 biodone(struct bio *bp) 3633 { 3634 struct mtx *mtxp; 3635 void (*done)(struct bio *); 3636 vm_offset_t start, end; 3637 3638 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) { 3639 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING; 3640 bp->bio_flags |= BIO_UNMAPPED; 3641 start = trunc_page((vm_offset_t)bp->bio_data); 3642 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length); 3643 bp->bio_data = unmapped_buf; 3644 pmap_qremove(start, OFF_TO_IDX(end - start)); 3645 vmem_free(transient_arena, start, end - start); 3646 atomic_add_int(&inflight_transient_maps, -1); 3647 } 3648 done = bp->bio_done; 3649 if (done == NULL) { 3650 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3651 mtx_lock(mtxp); 3652 bp->bio_flags |= BIO_DONE; 3653 wakeup(bp); 3654 mtx_unlock(mtxp); 3655 } else { 3656 bp->bio_flags |= BIO_DONE; 3657 done(bp); 3658 } 3659 } 3660 3661 /* 3662 * Wait for a BIO to finish. 3663 */ 3664 int 3665 biowait(struct bio *bp, const char *wchan) 3666 { 3667 struct mtx *mtxp; 3668 3669 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3670 mtx_lock(mtxp); 3671 while ((bp->bio_flags & BIO_DONE) == 0) 3672 msleep(bp, mtxp, PRIBIO, wchan, 0); 3673 mtx_unlock(mtxp); 3674 if (bp->bio_error != 0) 3675 return (bp->bio_error); 3676 if (!(bp->bio_flags & BIO_ERROR)) 3677 return (0); 3678 return (EIO); 3679 } 3680 3681 void 3682 biofinish(struct bio *bp, struct devstat *stat, int error) 3683 { 3684 3685 if (error) { 3686 bp->bio_error = error; 3687 bp->bio_flags |= BIO_ERROR; 3688 } 3689 if (stat != NULL) 3690 devstat_end_transaction_bio(stat, bp); 3691 biodone(bp); 3692 } 3693 3694 /* 3695 * bufwait: 3696 * 3697 * Wait for buffer I/O completion, returning error status. The buffer 3698 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3699 * error and cleared. 3700 */ 3701 int 3702 bufwait(struct buf *bp) 3703 { 3704 if (bp->b_iocmd == BIO_READ) 3705 bwait(bp, PRIBIO, "biord"); 3706 else 3707 bwait(bp, PRIBIO, "biowr"); 3708 if (bp->b_flags & B_EINTR) { 3709 bp->b_flags &= ~B_EINTR; 3710 return (EINTR); 3711 } 3712 if (bp->b_ioflags & BIO_ERROR) { 3713 return (bp->b_error ? bp->b_error : EIO); 3714 } else { 3715 return (0); 3716 } 3717 } 3718 3719 /* 3720 * Call back function from struct bio back up to struct buf. 3721 */ 3722 static void 3723 bufdonebio(struct bio *bip) 3724 { 3725 struct buf *bp; 3726 3727 bp = bip->bio_caller2; 3728 bp->b_resid = bip->bio_resid; 3729 bp->b_ioflags = bip->bio_flags; 3730 bp->b_error = bip->bio_error; 3731 if (bp->b_error) 3732 bp->b_ioflags |= BIO_ERROR; 3733 bufdone(bp); 3734 g_destroy_bio(bip); 3735 } 3736 3737 void 3738 dev_strategy(struct cdev *dev, struct buf *bp) 3739 { 3740 struct cdevsw *csw; 3741 int ref; 3742 3743 KASSERT(dev->si_refcount > 0, 3744 ("dev_strategy on un-referenced struct cdev *(%s) %p", 3745 devtoname(dev), dev)); 3746 3747 csw = dev_refthread(dev, &ref); 3748 dev_strategy_csw(dev, csw, bp); 3749 dev_relthread(dev, ref); 3750 } 3751 3752 void 3753 dev_strategy_csw(struct cdev *dev, struct cdevsw *csw, struct buf *bp) 3754 { 3755 struct bio *bip; 3756 3757 KASSERT(bp->b_iocmd == BIO_READ || bp->b_iocmd == BIO_WRITE, 3758 ("b_iocmd botch")); 3759 KASSERT(((dev->si_flags & SI_ETERNAL) != 0 && csw != NULL) || 3760 dev->si_threadcount > 0, 3761 ("dev_strategy_csw threadcount cdev *(%s) %p", devtoname(dev), 3762 dev)); 3763 if (csw == NULL) { 3764 bp->b_error = ENXIO; 3765 bp->b_ioflags = BIO_ERROR; 3766 bufdone(bp); 3767 return; 3768 } 3769 for (;;) { 3770 bip = g_new_bio(); 3771 if (bip != NULL) 3772 break; 3773 /* Try again later */ 3774 tsleep(&bp, PRIBIO, "dev_strat", hz/10); 3775 } 3776 bip->bio_cmd = bp->b_iocmd; 3777 bip->bio_offset = bp->b_iooffset; 3778 bip->bio_length = bp->b_bcount; 3779 bip->bio_bcount = bp->b_bcount; /* XXX: remove */ 3780 bdata2bio(bp, bip); 3781 bip->bio_done = bufdonebio; 3782 bip->bio_caller2 = bp; 3783 bip->bio_dev = dev; 3784 (*csw->d_strategy)(bip); 3785 } 3786 3787 /* 3788 * bufdone: 3789 * 3790 * Finish I/O on a buffer, optionally calling a completion function. 3791 * This is usually called from an interrupt so process blocking is 3792 * not allowed. 3793 * 3794 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3795 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3796 * assuming B_INVAL is clear. 3797 * 3798 * For the VMIO case, we set B_CACHE if the op was a read and no 3799 * read error occured, or if the op was a write. B_CACHE is never 3800 * set if the buffer is invalid or otherwise uncacheable. 3801 * 3802 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3803 * initiator to leave B_INVAL set to brelse the buffer out of existance 3804 * in the biodone routine. 3805 */ 3806 void 3807 bufdone(struct buf *bp) 3808 { 3809 struct bufobj *dropobj; 3810 void (*biodone)(struct buf *); 3811 3812 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 3813 dropobj = NULL; 3814 3815 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 3816 BUF_ASSERT_HELD(bp); 3817 3818 runningbufwakeup(bp); 3819 if (bp->b_iocmd == BIO_WRITE) 3820 dropobj = bp->b_bufobj; 3821 /* call optional completion function if requested */ 3822 if (bp->b_iodone != NULL) { 3823 biodone = bp->b_iodone; 3824 bp->b_iodone = NULL; 3825 (*biodone) (bp); 3826 if (dropobj) 3827 bufobj_wdrop(dropobj); 3828 return; 3829 } 3830 3831 bufdone_finish(bp); 3832 3833 if (dropobj) 3834 bufobj_wdrop(dropobj); 3835 } 3836 3837 void 3838 bufdone_finish(struct buf *bp) 3839 { 3840 BUF_ASSERT_HELD(bp); 3841 3842 if (!LIST_EMPTY(&bp->b_dep)) 3843 buf_complete(bp); 3844 3845 if (bp->b_flags & B_VMIO) { 3846 vm_ooffset_t foff; 3847 vm_page_t m; 3848 vm_object_t obj; 3849 struct vnode *vp; 3850 int bogus, i, iosize; 3851 3852 obj = bp->b_bufobj->bo_object; 3853 KASSERT(obj->paging_in_progress >= bp->b_npages, 3854 ("biodone_finish: paging in progress(%d) < b_npages(%d)", 3855 obj->paging_in_progress, bp->b_npages)); 3856 3857 vp = bp->b_vp; 3858 KASSERT(vp->v_holdcnt > 0, 3859 ("biodone_finish: vnode %p has zero hold count", vp)); 3860 KASSERT(vp->v_object != NULL, 3861 ("biodone_finish: vnode %p has no vm_object", vp)); 3862 3863 foff = bp->b_offset; 3864 KASSERT(bp->b_offset != NOOFFSET, 3865 ("biodone_finish: bp %p has no buffer offset", bp)); 3866 3867 /* 3868 * Set B_CACHE if the op was a normal read and no error 3869 * occured. B_CACHE is set for writes in the b*write() 3870 * routines. 3871 */ 3872 iosize = bp->b_bcount - bp->b_resid; 3873 if (bp->b_iocmd == BIO_READ && 3874 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 3875 !(bp->b_ioflags & BIO_ERROR)) { 3876 bp->b_flags |= B_CACHE; 3877 } 3878 bogus = 0; 3879 VM_OBJECT_WLOCK(obj); 3880 for (i = 0; i < bp->b_npages; i++) { 3881 int bogusflag = 0; 3882 int resid; 3883 3884 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 3885 if (resid > iosize) 3886 resid = iosize; 3887 3888 /* 3889 * cleanup bogus pages, restoring the originals 3890 */ 3891 m = bp->b_pages[i]; 3892 if (m == bogus_page) { 3893 bogus = bogusflag = 1; 3894 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3895 if (m == NULL) 3896 panic("biodone: page disappeared!"); 3897 bp->b_pages[i] = m; 3898 } 3899 KASSERT(OFF_TO_IDX(foff) == m->pindex, 3900 ("biodone_finish: foff(%jd)/pindex(%ju) mismatch", 3901 (intmax_t)foff, (uintmax_t)m->pindex)); 3902 3903 /* 3904 * In the write case, the valid and clean bits are 3905 * already changed correctly ( see bdwrite() ), so we 3906 * only need to do this here in the read case. 3907 */ 3908 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 3909 KASSERT((m->dirty & vm_page_bits(foff & 3910 PAGE_MASK, resid)) == 0, ("bufdone_finish:" 3911 " page %p has unexpected dirty bits", m)); 3912 vfs_page_set_valid(bp, foff, m); 3913 } 3914 3915 vm_page_sunbusy(m); 3916 vm_object_pip_subtract(obj, 1); 3917 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3918 iosize -= resid; 3919 } 3920 vm_object_pip_wakeupn(obj, 0); 3921 VM_OBJECT_WUNLOCK(obj); 3922 if (bogus && (bp->b_flags & B_UNMAPPED) == 0) { 3923 BUF_CHECK_MAPPED(bp); 3924 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3925 bp->b_pages, bp->b_npages); 3926 } 3927 } 3928 3929 /* 3930 * For asynchronous completions, release the buffer now. The brelse 3931 * will do a wakeup there if necessary - so no need to do a wakeup 3932 * here in the async case. The sync case always needs to do a wakeup. 3933 */ 3934 3935 if (bp->b_flags & B_ASYNC) { 3936 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 3937 brelse(bp); 3938 else 3939 bqrelse(bp); 3940 } else 3941 bdone(bp); 3942 } 3943 3944 /* 3945 * This routine is called in lieu of iodone in the case of 3946 * incomplete I/O. This keeps the busy status for pages 3947 * consistant. 3948 */ 3949 void 3950 vfs_unbusy_pages(struct buf *bp) 3951 { 3952 int i; 3953 vm_object_t obj; 3954 vm_page_t m; 3955 3956 runningbufwakeup(bp); 3957 if (!(bp->b_flags & B_VMIO)) 3958 return; 3959 3960 obj = bp->b_bufobj->bo_object; 3961 VM_OBJECT_WLOCK(obj); 3962 for (i = 0; i < bp->b_npages; i++) { 3963 m = bp->b_pages[i]; 3964 if (m == bogus_page) { 3965 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 3966 if (!m) 3967 panic("vfs_unbusy_pages: page missing\n"); 3968 bp->b_pages[i] = m; 3969 if ((bp->b_flags & B_UNMAPPED) == 0) { 3970 BUF_CHECK_MAPPED(bp); 3971 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3972 bp->b_pages, bp->b_npages); 3973 } else 3974 BUF_CHECK_UNMAPPED(bp); 3975 } 3976 vm_object_pip_subtract(obj, 1); 3977 vm_page_sunbusy(m); 3978 } 3979 vm_object_pip_wakeupn(obj, 0); 3980 VM_OBJECT_WUNLOCK(obj); 3981 } 3982 3983 /* 3984 * vfs_page_set_valid: 3985 * 3986 * Set the valid bits in a page based on the supplied offset. The 3987 * range is restricted to the buffer's size. 3988 * 3989 * This routine is typically called after a read completes. 3990 */ 3991 static void 3992 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3993 { 3994 vm_ooffset_t eoff; 3995 3996 /* 3997 * Compute the end offset, eoff, such that [off, eoff) does not span a 3998 * page boundary and eoff is not greater than the end of the buffer. 3999 * The end of the buffer, in this case, is our file EOF, not the 4000 * allocation size of the buffer. 4001 */ 4002 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_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 > off) 4011 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off); 4012 } 4013 4014 /* 4015 * vfs_page_set_validclean: 4016 * 4017 * Set the valid bits and clear the dirty bits in a page based on the 4018 * supplied offset. The range is restricted to the buffer's size. 4019 */ 4020 static void 4021 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4022 { 4023 vm_ooffset_t soff, eoff; 4024 4025 /* 4026 * Start and end offsets in buffer. eoff - soff may not cross a 4027 * page boundry or cross the end of the buffer. The end of the 4028 * buffer, in this case, is our file EOF, not the allocation size 4029 * of the buffer. 4030 */ 4031 soff = off; 4032 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4033 if (eoff > bp->b_offset + bp->b_bcount) 4034 eoff = bp->b_offset + bp->b_bcount; 4035 4036 /* 4037 * Set valid range. This is typically the entire buffer and thus the 4038 * entire page. 4039 */ 4040 if (eoff > soff) { 4041 vm_page_set_validclean( 4042 m, 4043 (vm_offset_t) (soff & PAGE_MASK), 4044 (vm_offset_t) (eoff - soff) 4045 ); 4046 } 4047 } 4048 4049 /* 4050 * Ensure that all buffer pages are not exclusive busied. If any page is 4051 * exclusive busy, drain it. 4052 */ 4053 void 4054 vfs_drain_busy_pages(struct buf *bp) 4055 { 4056 vm_page_t m; 4057 int i, last_busied; 4058 4059 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object); 4060 last_busied = 0; 4061 for (i = 0; i < bp->b_npages; i++) { 4062 m = bp->b_pages[i]; 4063 if (vm_page_xbusied(m)) { 4064 for (; last_busied < i; last_busied++) 4065 vm_page_sbusy(bp->b_pages[last_busied]); 4066 while (vm_page_xbusied(m)) { 4067 vm_page_lock(m); 4068 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4069 vm_page_busy_sleep(m, "vbpage"); 4070 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4071 } 4072 } 4073 } 4074 for (i = 0; i < last_busied; i++) 4075 vm_page_sunbusy(bp->b_pages[i]); 4076 } 4077 4078 /* 4079 * This routine is called before a device strategy routine. 4080 * It is used to tell the VM system that paging I/O is in 4081 * progress, and treat the pages associated with the buffer 4082 * almost as being exclusive busy. Also the object paging_in_progress 4083 * flag is handled to make sure that the object doesn't become 4084 * inconsistant. 4085 * 4086 * Since I/O has not been initiated yet, certain buffer flags 4087 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 4088 * and should be ignored. 4089 */ 4090 void 4091 vfs_busy_pages(struct buf *bp, int clear_modify) 4092 { 4093 int i, bogus; 4094 vm_object_t obj; 4095 vm_ooffset_t foff; 4096 vm_page_t m; 4097 4098 if (!(bp->b_flags & B_VMIO)) 4099 return; 4100 4101 obj = bp->b_bufobj->bo_object; 4102 foff = bp->b_offset; 4103 KASSERT(bp->b_offset != NOOFFSET, 4104 ("vfs_busy_pages: no buffer offset")); 4105 VM_OBJECT_WLOCK(obj); 4106 vfs_drain_busy_pages(bp); 4107 if (bp->b_bufsize != 0) 4108 vfs_setdirty_locked_object(bp); 4109 bogus = 0; 4110 for (i = 0; i < bp->b_npages; i++) { 4111 m = bp->b_pages[i]; 4112 4113 if ((bp->b_flags & B_CLUSTER) == 0) { 4114 vm_object_pip_add(obj, 1); 4115 vm_page_sbusy(m); 4116 } 4117 /* 4118 * When readying a buffer for a read ( i.e 4119 * clear_modify == 0 ), it is important to do 4120 * bogus_page replacement for valid pages in 4121 * partially instantiated buffers. Partially 4122 * instantiated buffers can, in turn, occur when 4123 * reconstituting a buffer from its VM backing store 4124 * base. We only have to do this if B_CACHE is 4125 * clear ( which causes the I/O to occur in the 4126 * first place ). The replacement prevents the read 4127 * I/O from overwriting potentially dirty VM-backed 4128 * pages. XXX bogus page replacement is, uh, bogus. 4129 * It may not work properly with small-block devices. 4130 * We need to find a better way. 4131 */ 4132 if (clear_modify) { 4133 pmap_remove_write(m); 4134 vfs_page_set_validclean(bp, foff, m); 4135 } else if (m->valid == VM_PAGE_BITS_ALL && 4136 (bp->b_flags & B_CACHE) == 0) { 4137 bp->b_pages[i] = bogus_page; 4138 bogus++; 4139 } 4140 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4141 } 4142 VM_OBJECT_WUNLOCK(obj); 4143 if (bogus && (bp->b_flags & B_UNMAPPED) == 0) { 4144 BUF_CHECK_MAPPED(bp); 4145 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4146 bp->b_pages, bp->b_npages); 4147 } 4148 } 4149 4150 /* 4151 * vfs_bio_set_valid: 4152 * 4153 * Set the range within the buffer to valid. The range is 4154 * relative to the beginning of the buffer, b_offset. Note that 4155 * b_offset itself may be offset from the beginning of the first 4156 * page. 4157 */ 4158 void 4159 vfs_bio_set_valid(struct buf *bp, int base, int size) 4160 { 4161 int i, n; 4162 vm_page_t m; 4163 4164 if (!(bp->b_flags & B_VMIO)) 4165 return; 4166 4167 /* 4168 * Fixup base to be relative to beginning of first page. 4169 * Set initial n to be the maximum number of bytes in the 4170 * first page that can be validated. 4171 */ 4172 base += (bp->b_offset & PAGE_MASK); 4173 n = PAGE_SIZE - (base & PAGE_MASK); 4174 4175 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4176 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4177 m = bp->b_pages[i]; 4178 if (n > size) 4179 n = size; 4180 vm_page_set_valid_range(m, base & PAGE_MASK, n); 4181 base += n; 4182 size -= n; 4183 n = PAGE_SIZE; 4184 } 4185 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4186 } 4187 4188 /* 4189 * vfs_bio_clrbuf: 4190 * 4191 * If the specified buffer is a non-VMIO buffer, clear the entire 4192 * buffer. If the specified buffer is a VMIO buffer, clear and 4193 * validate only the previously invalid portions of the buffer. 4194 * This routine essentially fakes an I/O, so we need to clear 4195 * BIO_ERROR and B_INVAL. 4196 * 4197 * Note that while we only theoretically need to clear through b_bcount, 4198 * we go ahead and clear through b_bufsize. 4199 */ 4200 void 4201 vfs_bio_clrbuf(struct buf *bp) 4202 { 4203 int i, j, mask, sa, ea, slide; 4204 4205 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 4206 clrbuf(bp); 4207 return; 4208 } 4209 bp->b_flags &= ~B_INVAL; 4210 bp->b_ioflags &= ~BIO_ERROR; 4211 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4212 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 4213 (bp->b_offset & PAGE_MASK) == 0) { 4214 if (bp->b_pages[0] == bogus_page) 4215 goto unlock; 4216 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 4217 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object); 4218 if ((bp->b_pages[0]->valid & mask) == mask) 4219 goto unlock; 4220 if ((bp->b_pages[0]->valid & mask) == 0) { 4221 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize); 4222 bp->b_pages[0]->valid |= mask; 4223 goto unlock; 4224 } 4225 } 4226 sa = bp->b_offset & PAGE_MASK; 4227 slide = 0; 4228 for (i = 0; i < bp->b_npages; i++, sa = 0) { 4229 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize); 4230 ea = slide & PAGE_MASK; 4231 if (ea == 0) 4232 ea = PAGE_SIZE; 4233 if (bp->b_pages[i] == bogus_page) 4234 continue; 4235 j = sa / DEV_BSIZE; 4236 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 4237 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object); 4238 if ((bp->b_pages[i]->valid & mask) == mask) 4239 continue; 4240 if ((bp->b_pages[i]->valid & mask) == 0) 4241 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa); 4242 else { 4243 for (; sa < ea; sa += DEV_BSIZE, j++) { 4244 if ((bp->b_pages[i]->valid & (1 << j)) == 0) { 4245 pmap_zero_page_area(bp->b_pages[i], 4246 sa, DEV_BSIZE); 4247 } 4248 } 4249 } 4250 bp->b_pages[i]->valid |= mask; 4251 } 4252 unlock: 4253 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4254 bp->b_resid = 0; 4255 } 4256 4257 void 4258 vfs_bio_bzero_buf(struct buf *bp, int base, int size) 4259 { 4260 vm_page_t m; 4261 int i, n; 4262 4263 if ((bp->b_flags & B_UNMAPPED) == 0) { 4264 BUF_CHECK_MAPPED(bp); 4265 bzero(bp->b_data + base, size); 4266 } else { 4267 BUF_CHECK_UNMAPPED(bp); 4268 n = PAGE_SIZE - (base & PAGE_MASK); 4269 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4270 m = bp->b_pages[i]; 4271 if (n > size) 4272 n = size; 4273 pmap_zero_page_area(m, base & PAGE_MASK, n); 4274 base += n; 4275 size -= n; 4276 n = PAGE_SIZE; 4277 } 4278 } 4279 } 4280 4281 /* 4282 * vm_hold_load_pages and vm_hold_free_pages get pages into 4283 * a buffers address space. The pages are anonymous and are 4284 * not associated with a file object. 4285 */ 4286 static void 4287 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4288 { 4289 vm_offset_t pg; 4290 vm_page_t p; 4291 int index; 4292 4293 BUF_CHECK_MAPPED(bp); 4294 4295 to = round_page(to); 4296 from = round_page(from); 4297 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4298 4299 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 4300 tryagain: 4301 /* 4302 * note: must allocate system pages since blocking here 4303 * could interfere with paging I/O, no matter which 4304 * process we are. 4305 */ 4306 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ | 4307 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT)); 4308 if (p == NULL) { 4309 VM_WAIT; 4310 goto tryagain; 4311 } 4312 pmap_qenter(pg, &p, 1); 4313 bp->b_pages[index] = p; 4314 } 4315 bp->b_npages = index; 4316 } 4317 4318 /* Return pages associated with this buf to the vm system */ 4319 static void 4320 vm_hold_free_pages(struct buf *bp, int newbsize) 4321 { 4322 vm_offset_t from; 4323 vm_page_t p; 4324 int index, newnpages; 4325 4326 BUF_CHECK_MAPPED(bp); 4327 4328 from = round_page((vm_offset_t)bp->b_data + newbsize); 4329 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4330 if (bp->b_npages > newnpages) 4331 pmap_qremove(from, bp->b_npages - newnpages); 4332 for (index = newnpages; index < bp->b_npages; index++) { 4333 p = bp->b_pages[index]; 4334 bp->b_pages[index] = NULL; 4335 if (vm_page_sbusied(p)) 4336 printf("vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 4337 (intmax_t)bp->b_blkno, (intmax_t)bp->b_lblkno); 4338 p->wire_count--; 4339 vm_page_free(p); 4340 atomic_subtract_int(&vm_cnt.v_wire_count, 1); 4341 } 4342 bp->b_npages = newnpages; 4343 } 4344 4345 /* 4346 * Map an IO request into kernel virtual address space. 4347 * 4348 * All requests are (re)mapped into kernel VA space. 4349 * Notice that we use b_bufsize for the size of the buffer 4350 * to be mapped. b_bcount might be modified by the driver. 4351 * 4352 * Note that even if the caller determines that the address space should 4353 * be valid, a race or a smaller-file mapped into a larger space may 4354 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 4355 * check the return value. 4356 */ 4357 int 4358 vmapbuf(struct buf *bp, int mapbuf) 4359 { 4360 caddr_t kva; 4361 vm_prot_t prot; 4362 int pidx; 4363 4364 if (bp->b_bufsize < 0) 4365 return (-1); 4366 prot = VM_PROT_READ; 4367 if (bp->b_iocmd == BIO_READ) 4368 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 4369 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 4370 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages, 4371 btoc(MAXPHYS))) < 0) 4372 return (-1); 4373 bp->b_npages = pidx; 4374 if (mapbuf || !unmapped_buf_allowed) { 4375 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx); 4376 kva = bp->b_saveaddr; 4377 bp->b_saveaddr = bp->b_data; 4378 bp->b_data = kva + (((vm_offset_t)bp->b_data) & PAGE_MASK); 4379 bp->b_flags &= ~B_UNMAPPED; 4380 } else { 4381 bp->b_flags |= B_UNMAPPED; 4382 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK; 4383 bp->b_saveaddr = bp->b_data; 4384 bp->b_data = unmapped_buf; 4385 } 4386 return(0); 4387 } 4388 4389 /* 4390 * Free the io map PTEs associated with this IO operation. 4391 * We also invalidate the TLB entries and restore the original b_addr. 4392 */ 4393 void 4394 vunmapbuf(struct buf *bp) 4395 { 4396 int npages; 4397 4398 npages = bp->b_npages; 4399 if (bp->b_flags & B_UNMAPPED) 4400 bp->b_flags &= ~B_UNMAPPED; 4401 else 4402 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 4403 vm_page_unhold_pages(bp->b_pages, npages); 4404 4405 bp->b_data = bp->b_saveaddr; 4406 } 4407 4408 void 4409 bdone(struct buf *bp) 4410 { 4411 struct mtx *mtxp; 4412 4413 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4414 mtx_lock(mtxp); 4415 bp->b_flags |= B_DONE; 4416 wakeup(bp); 4417 mtx_unlock(mtxp); 4418 } 4419 4420 void 4421 bwait(struct buf *bp, u_char pri, const char *wchan) 4422 { 4423 struct mtx *mtxp; 4424 4425 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4426 mtx_lock(mtxp); 4427 while ((bp->b_flags & B_DONE) == 0) 4428 msleep(bp, mtxp, pri, wchan, 0); 4429 mtx_unlock(mtxp); 4430 } 4431 4432 int 4433 bufsync(struct bufobj *bo, int waitfor) 4434 { 4435 4436 return (VOP_FSYNC(bo->__bo_vnode, waitfor, curthread)); 4437 } 4438 4439 void 4440 bufstrategy(struct bufobj *bo, struct buf *bp) 4441 { 4442 int i = 0; 4443 struct vnode *vp; 4444 4445 vp = bp->b_vp; 4446 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 4447 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 4448 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 4449 i = VOP_STRATEGY(vp, bp); 4450 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 4451 } 4452 4453 void 4454 bufobj_wrefl(struct bufobj *bo) 4455 { 4456 4457 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4458 ASSERT_BO_WLOCKED(bo); 4459 bo->bo_numoutput++; 4460 } 4461 4462 void 4463 bufobj_wref(struct bufobj *bo) 4464 { 4465 4466 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4467 BO_LOCK(bo); 4468 bo->bo_numoutput++; 4469 BO_UNLOCK(bo); 4470 } 4471 4472 void 4473 bufobj_wdrop(struct bufobj *bo) 4474 { 4475 4476 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 4477 BO_LOCK(bo); 4478 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 4479 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 4480 bo->bo_flag &= ~BO_WWAIT; 4481 wakeup(&bo->bo_numoutput); 4482 } 4483 BO_UNLOCK(bo); 4484 } 4485 4486 int 4487 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 4488 { 4489 int error; 4490 4491 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 4492 ASSERT_BO_WLOCKED(bo); 4493 error = 0; 4494 while (bo->bo_numoutput) { 4495 bo->bo_flag |= BO_WWAIT; 4496 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo), 4497 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 4498 if (error) 4499 break; 4500 } 4501 return (error); 4502 } 4503 4504 void 4505 bpin(struct buf *bp) 4506 { 4507 struct mtx *mtxp; 4508 4509 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4510 mtx_lock(mtxp); 4511 bp->b_pin_count++; 4512 mtx_unlock(mtxp); 4513 } 4514 4515 void 4516 bunpin(struct buf *bp) 4517 { 4518 struct mtx *mtxp; 4519 4520 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4521 mtx_lock(mtxp); 4522 if (--bp->b_pin_count == 0) 4523 wakeup(bp); 4524 mtx_unlock(mtxp); 4525 } 4526 4527 void 4528 bunpin_wait(struct buf *bp) 4529 { 4530 struct mtx *mtxp; 4531 4532 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4533 mtx_lock(mtxp); 4534 while (bp->b_pin_count > 0) 4535 msleep(bp, mtxp, PRIBIO, "bwunpin", 0); 4536 mtx_unlock(mtxp); 4537 } 4538 4539 /* 4540 * Set bio_data or bio_ma for struct bio from the struct buf. 4541 */ 4542 void 4543 bdata2bio(struct buf *bp, struct bio *bip) 4544 { 4545 4546 if ((bp->b_flags & B_UNMAPPED) != 0) { 4547 KASSERT(unmapped_buf_allowed, ("unmapped")); 4548 bip->bio_ma = bp->b_pages; 4549 bip->bio_ma_n = bp->b_npages; 4550 bip->bio_data = unmapped_buf; 4551 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 4552 bip->bio_flags |= BIO_UNMAPPED; 4553 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) / 4554 PAGE_SIZE == bp->b_npages, 4555 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset, 4556 (long long)bip->bio_length, bip->bio_ma_n)); 4557 } else { 4558 bip->bio_data = bp->b_data; 4559 bip->bio_ma = NULL; 4560 } 4561 } 4562 4563 #include "opt_ddb.h" 4564 #ifdef DDB 4565 #include <ddb/ddb.h> 4566 4567 /* DDB command to show buffer data */ 4568 DB_SHOW_COMMAND(buffer, db_show_buffer) 4569 { 4570 /* get args */ 4571 struct buf *bp = (struct buf *)addr; 4572 4573 if (!have_addr) { 4574 db_printf("usage: show buffer <addr>\n"); 4575 return; 4576 } 4577 4578 db_printf("buf at %p\n", bp); 4579 db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n", 4580 (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags, 4581 PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS); 4582 db_printf( 4583 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 4584 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, " 4585 "b_dep = %p\n", 4586 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 4587 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 4588 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first); 4589 if (bp->b_npages) { 4590 int i; 4591 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 4592 for (i = 0; i < bp->b_npages; i++) { 4593 vm_page_t m; 4594 m = bp->b_pages[i]; 4595 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 4596 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 4597 if ((i + 1) < bp->b_npages) 4598 db_printf(","); 4599 } 4600 db_printf("\n"); 4601 } 4602 db_printf(" "); 4603 BUF_LOCKPRINTINFO(bp); 4604 } 4605 4606 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 4607 { 4608 struct buf *bp; 4609 int i; 4610 4611 for (i = 0; i < nbuf; i++) { 4612 bp = &buf[i]; 4613 if (BUF_ISLOCKED(bp)) { 4614 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4615 db_printf("\n"); 4616 } 4617 } 4618 } 4619 4620 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 4621 { 4622 struct vnode *vp; 4623 struct buf *bp; 4624 4625 if (!have_addr) { 4626 db_printf("usage: show vnodebufs <addr>\n"); 4627 return; 4628 } 4629 vp = (struct vnode *)addr; 4630 db_printf("Clean buffers:\n"); 4631 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 4632 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4633 db_printf("\n"); 4634 } 4635 db_printf("Dirty buffers:\n"); 4636 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 4637 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4638 db_printf("\n"); 4639 } 4640 } 4641 4642 DB_COMMAND(countfreebufs, db_coundfreebufs) 4643 { 4644 struct buf *bp; 4645 int i, used = 0, nfree = 0; 4646 4647 if (have_addr) { 4648 db_printf("usage: countfreebufs\n"); 4649 return; 4650 } 4651 4652 for (i = 0; i < nbuf; i++) { 4653 bp = &buf[i]; 4654 if ((bp->b_flags & B_INFREECNT) != 0) 4655 nfree++; 4656 else 4657 used++; 4658 } 4659 4660 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 4661 nfree + used); 4662 db_printf("numfreebuffers is %d\n", numfreebuffers); 4663 } 4664 #endif /* DDB */ 4665