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