1 /*- 2 * Copyright (c) 2004 Poul-Henning Kamp 3 * Copyright (c) 1994,1997 John S. Dyson 4 * Copyright (c) 2013 The FreeBSD Foundation 5 * All rights reserved. 6 * 7 * Portions of this software were developed by Konstantin Belousov 8 * under sponsorship from the FreeBSD Foundation. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 /* 33 * this file contains a new buffer I/O scheme implementing a coherent 34 * VM object and buffer cache scheme. Pains have been taken to make 35 * sure that the performance degradation associated with schemes such 36 * as this is not realized. 37 * 38 * Author: John S. Dyson 39 * Significant help during the development and debugging phases 40 * had been provided by David Greenman, also of the FreeBSD core team. 41 * 42 * see man buf(9) for more info. 43 */ 44 45 #include <sys/cdefs.h> 46 __FBSDID("$FreeBSD$"); 47 48 #include <sys/param.h> 49 #include <sys/systm.h> 50 #include <sys/bio.h> 51 #include <sys/conf.h> 52 #include <sys/buf.h> 53 #include <sys/devicestat.h> 54 #include <sys/eventhandler.h> 55 #include <sys/fail.h> 56 #include <sys/limits.h> 57 #include <sys/lock.h> 58 #include <sys/malloc.h> 59 #include <sys/mount.h> 60 #include <sys/mutex.h> 61 #include <sys/kernel.h> 62 #include <sys/kthread.h> 63 #include <sys/proc.h> 64 #include <sys/resourcevar.h> 65 #include <sys/rwlock.h> 66 #include <sys/sysctl.h> 67 #include <sys/vmem.h> 68 #include <sys/vmmeter.h> 69 #include <sys/vnode.h> 70 #include <geom/geom.h> 71 #include <vm/vm.h> 72 #include <vm/vm_param.h> 73 #include <vm/vm_kern.h> 74 #include <vm/vm_pageout.h> 75 #include <vm/vm_page.h> 76 #include <vm/vm_object.h> 77 #include <vm/vm_extern.h> 78 #include <vm/vm_map.h> 79 #include "opt_compat.h" 80 #include "opt_swap.h" 81 82 static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer"); 83 84 struct bio_ops bioops; /* I/O operation notification */ 85 86 struct buf_ops buf_ops_bio = { 87 .bop_name = "buf_ops_bio", 88 .bop_write = bufwrite, 89 .bop_strategy = bufstrategy, 90 .bop_sync = bufsync, 91 .bop_bdflush = bufbdflush, 92 }; 93 94 /* 95 * XXX buf is global because kern_shutdown.c and ffs_checkoverlap has 96 * carnal knowledge of buffers. This knowledge should be moved to vfs_bio.c. 97 */ 98 struct buf *buf; /* buffer header pool */ 99 caddr_t unmapped_buf; 100 101 /* Used below and for softdep flushing threads in ufs/ffs/ffs_softdep.c */ 102 struct proc *bufdaemonproc; 103 104 static int inmem(struct vnode *vp, daddr_t blkno); 105 static void vm_hold_free_pages(struct buf *bp, int newbsize); 106 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from, 107 vm_offset_t to); 108 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m); 109 static void vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, 110 vm_page_t m); 111 static void vfs_clean_pages_dirty_buf(struct buf *bp); 112 static void vfs_setdirty_locked_object(struct buf *bp); 113 static void vfs_vmio_release(struct buf *bp); 114 static int vfs_bio_clcheck(struct vnode *vp, int size, 115 daddr_t lblkno, daddr_t blkno); 116 static int buf_flush(struct vnode *vp, int); 117 static int flushbufqueues(struct vnode *, int, int); 118 static void buf_daemon(void); 119 static void bremfreel(struct buf *bp); 120 static __inline void bd_wakeup(void); 121 static int sysctl_runningspace(SYSCTL_HANDLER_ARGS); 122 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 123 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 124 static int sysctl_bufspace(SYSCTL_HANDLER_ARGS); 125 #endif 126 127 int vmiodirenable = TRUE; 128 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, 129 "Use the VM system for directory writes"); 130 long runningbufspace; 131 SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 132 "Amount of presently outstanding async buffer io"); 133 static long bufspace; 134 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 135 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 136 SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD, 137 &bufspace, 0, sysctl_bufspace, "L", "Virtual memory used for buffers"); 138 #else 139 SYSCTL_LONG(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, 140 "Virtual memory used for buffers"); 141 #endif 142 static long unmapped_bufspace; 143 SYSCTL_LONG(_vfs, OID_AUTO, unmapped_bufspace, CTLFLAG_RD, 144 &unmapped_bufspace, 0, 145 "Amount of unmapped buffers, inclusive in the bufspace"); 146 static long maxbufspace; 147 SYSCTL_LONG(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0, 148 "Maximum allowed value of bufspace (including buf_daemon)"); 149 static long bufmallocspace; 150 SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 151 "Amount of malloced memory for buffers"); 152 static long maxbufmallocspace; 153 SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0, 154 "Maximum amount of malloced memory for buffers"); 155 static long lobufspace; 156 SYSCTL_LONG(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0, 157 "Minimum amount of buffers we want to have"); 158 long hibufspace; 159 SYSCTL_LONG(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0, 160 "Maximum allowed value of bufspace (excluding buf_daemon)"); 161 static int bufreusecnt; 162 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0, 163 "Number of times we have reused a buffer"); 164 static int buffreekvacnt; 165 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0, 166 "Number of times we have freed the KVA space from some buffer"); 167 static int bufdefragcnt; 168 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0, 169 "Number of times we have had to repeat buffer allocation to defragment"); 170 static long lorunningspace; 171 SYSCTL_PROC(_vfs, OID_AUTO, lorunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE | 172 CTLFLAG_RW, &lorunningspace, 0, sysctl_runningspace, "L", 173 "Minimum preferred space used for in-progress I/O"); 174 static long hirunningspace; 175 SYSCTL_PROC(_vfs, OID_AUTO, hirunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE | 176 CTLFLAG_RW, &hirunningspace, 0, sysctl_runningspace, "L", 177 "Maximum amount of space to use for in-progress I/O"); 178 int dirtybufferflushes; 179 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes, 180 0, "Number of bdwrite to bawrite conversions to limit dirty buffers"); 181 int bdwriteskip; 182 SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip, 183 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk"); 184 int altbufferflushes; 185 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes, 186 0, "Number of fsync flushes to limit dirty buffers"); 187 static int recursiveflushes; 188 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes, 189 0, "Number of flushes skipped due to being recursive"); 190 static int numdirtybuffers; 191 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0, 192 "Number of buffers that are dirty (has unwritten changes) at the moment"); 193 static int lodirtybuffers; 194 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0, 195 "How many buffers we want to have free before bufdaemon can sleep"); 196 static int hidirtybuffers; 197 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0, 198 "When the number of dirty buffers is considered severe"); 199 int dirtybufthresh; 200 SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh, 201 0, "Number of bdwrite to bawrite conversions to clear dirty buffers"); 202 static int numfreebuffers; 203 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, 204 "Number of free buffers"); 205 static int lofreebuffers; 206 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0, 207 "XXX Unused"); 208 static int hifreebuffers; 209 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0, 210 "XXX Complicatedly unused"); 211 static int getnewbufcalls; 212 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0, 213 "Number of calls to getnewbuf"); 214 static int getnewbufrestarts; 215 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0, 216 "Number of times getnewbuf has had to restart a buffer aquisition"); 217 static int mappingrestarts; 218 SYSCTL_INT(_vfs, OID_AUTO, mappingrestarts, CTLFLAG_RW, &mappingrestarts, 0, 219 "Number of times getblk has had to restart a buffer mapping for " 220 "unmapped buffer"); 221 static int flushbufqtarget = 100; 222 SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0, 223 "Amount of work to do in flushbufqueues when helping bufdaemon"); 224 static long notbufdflushes; 225 SYSCTL_LONG(_vfs, OID_AUTO, notbufdflushes, CTLFLAG_RD, ¬bufdflushes, 0, 226 "Number of dirty buffer flushes done by the bufdaemon helpers"); 227 static long barrierwrites; 228 SYSCTL_LONG(_vfs, OID_AUTO, barrierwrites, CTLFLAG_RW, &barrierwrites, 0, 229 "Number of barrier writes"); 230 SYSCTL_INT(_vfs, OID_AUTO, unmapped_buf_allowed, CTLFLAG_RD, 231 &unmapped_buf_allowed, 0, 232 "Permit the use of the unmapped i/o"); 233 234 /* 235 * Lock for the non-dirty bufqueues 236 */ 237 static struct mtx_padalign bqclean; 238 239 /* 240 * Lock for the dirty queue. 241 */ 242 static struct mtx_padalign bqdirty; 243 244 /* 245 * This lock synchronizes access to bd_request. 246 */ 247 static struct mtx_padalign bdlock; 248 249 /* 250 * This lock protects the runningbufreq and synchronizes runningbufwakeup and 251 * waitrunningbufspace(). 252 */ 253 static struct mtx_padalign rbreqlock; 254 255 /* 256 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it. 257 */ 258 static struct rwlock_padalign nblock; 259 260 /* 261 * Lock that protects bdirtywait. 262 */ 263 static struct mtx_padalign bdirtylock; 264 265 /* 266 * Wakeup point for bufdaemon, as well as indicator of whether it is already 267 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it 268 * is idling. 269 */ 270 static int bd_request; 271 272 /* 273 * Request for the buf daemon to write more buffers than is indicated by 274 * lodirtybuf. This may be necessary to push out excess dependencies or 275 * defragment the address space where a simple count of the number of dirty 276 * buffers is insufficient to characterize the demand for flushing them. 277 */ 278 static int bd_speedupreq; 279 280 /* 281 * bogus page -- for I/O to/from partially complete buffers 282 * this is a temporary solution to the problem, but it is not 283 * really that bad. it would be better to split the buffer 284 * for input in the case of buffers partially already in memory, 285 * but the code is intricate enough already. 286 */ 287 vm_page_t bogus_page; 288 289 /* 290 * Synchronization (sleep/wakeup) variable for active buffer space requests. 291 * Set when wait starts, cleared prior to wakeup(). 292 * Used in runningbufwakeup() and waitrunningbufspace(). 293 */ 294 static int runningbufreq; 295 296 /* 297 * Synchronization (sleep/wakeup) variable for buffer requests. 298 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done 299 * by and/or. 300 * Used in numdirtywakeup(), bufspacewakeup(), bufcountadd(), bwillwrite(), 301 * getnewbuf(), and getblk(). 302 */ 303 static volatile int needsbuffer; 304 305 /* 306 * Synchronization for bwillwrite() waiters. 307 */ 308 static int bdirtywait; 309 310 /* 311 * Definitions for the buffer free lists. 312 */ 313 #define BUFFER_QUEUES 5 /* number of free buffer queues */ 314 315 #define QUEUE_NONE 0 /* on no queue */ 316 #define QUEUE_CLEAN 1 /* non-B_DELWRI buffers */ 317 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */ 318 #define QUEUE_EMPTYKVA 3 /* empty buffer headers w/KVA assignment */ 319 #define QUEUE_EMPTY 4 /* empty buffer headers */ 320 #define QUEUE_SENTINEL 1024 /* not an queue index, but mark for sentinel */ 321 322 /* Queues for free buffers with various properties */ 323 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } }; 324 #ifdef INVARIANTS 325 static int bq_len[BUFFER_QUEUES]; 326 #endif 327 328 /* 329 * Single global constant for BUF_WMESG, to avoid getting multiple references. 330 * buf_wmesg is referred from macros. 331 */ 332 const char *buf_wmesg = BUF_WMESG; 333 334 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 335 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ 336 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 337 338 static int 339 sysctl_runningspace(SYSCTL_HANDLER_ARGS) 340 { 341 long value; 342 int error; 343 344 value = *(long *)arg1; 345 error = sysctl_handle_long(oidp, &value, 0, req); 346 if (error != 0 || req->newptr == NULL) 347 return (error); 348 mtx_lock(&rbreqlock); 349 if (arg1 == &hirunningspace) { 350 if (value < lorunningspace) 351 error = EINVAL; 352 else 353 hirunningspace = value; 354 } else { 355 KASSERT(arg1 == &lorunningspace, 356 ("%s: unknown arg1", __func__)); 357 if (value > hirunningspace) 358 error = EINVAL; 359 else 360 lorunningspace = value; 361 } 362 mtx_unlock(&rbreqlock); 363 return (error); 364 } 365 366 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 367 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 368 static int 369 sysctl_bufspace(SYSCTL_HANDLER_ARGS) 370 { 371 long lvalue; 372 int ivalue; 373 374 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long)) 375 return (sysctl_handle_long(oidp, arg1, arg2, req)); 376 lvalue = *(long *)arg1; 377 if (lvalue > INT_MAX) 378 /* On overflow, still write out a long to trigger ENOMEM. */ 379 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 380 ivalue = lvalue; 381 return (sysctl_handle_int(oidp, &ivalue, 0, req)); 382 } 383 #endif 384 385 /* 386 * bqlock: 387 * 388 * Return the appropriate queue lock based on the index. 389 */ 390 static inline struct mtx * 391 bqlock(int qindex) 392 { 393 394 if (qindex == QUEUE_DIRTY) 395 return (struct mtx *)(&bqdirty); 396 return (struct mtx *)(&bqclean); 397 } 398 399 /* 400 * bdirtywakeup: 401 * 402 * Wakeup any bwillwrite() waiters. 403 */ 404 static void 405 bdirtywakeup(void) 406 { 407 mtx_lock(&bdirtylock); 408 if (bdirtywait) { 409 bdirtywait = 0; 410 wakeup(&bdirtywait); 411 } 412 mtx_unlock(&bdirtylock); 413 } 414 415 /* 416 * bdirtysub: 417 * 418 * Decrement the numdirtybuffers count by one and wakeup any 419 * threads blocked in bwillwrite(). 420 */ 421 static void 422 bdirtysub(void) 423 { 424 425 if (atomic_fetchadd_int(&numdirtybuffers, -1) == 426 (lodirtybuffers + hidirtybuffers) / 2) 427 bdirtywakeup(); 428 } 429 430 /* 431 * bdirtyadd: 432 * 433 * Increment the numdirtybuffers count by one and wakeup the buf 434 * daemon if needed. 435 */ 436 static void 437 bdirtyadd(void) 438 { 439 440 /* 441 * Only do the wakeup once as we cross the boundary. The 442 * buf daemon will keep running until the condition clears. 443 */ 444 if (atomic_fetchadd_int(&numdirtybuffers, 1) == 445 (lodirtybuffers + hidirtybuffers) / 2) 446 bd_wakeup(); 447 } 448 449 /* 450 * bufspacewakeup: 451 * 452 * Called when buffer space is potentially available for recovery. 453 * getnewbuf() will block on this flag when it is unable to free 454 * sufficient buffer space. Buffer space becomes recoverable when 455 * bp's get placed back in the queues. 456 */ 457 458 static __inline void 459 bufspacewakeup(void) 460 { 461 int need_wakeup, on; 462 463 /* 464 * If someone is waiting for BUF space, wake them up. Even 465 * though we haven't freed the kva space yet, the waiting 466 * process will be able to now. 467 */ 468 rw_rlock(&nblock); 469 for (;;) { 470 need_wakeup = 0; 471 on = needsbuffer; 472 if ((on & VFS_BIO_NEED_BUFSPACE) == 0) 473 break; 474 need_wakeup = 1; 475 if (atomic_cmpset_rel_int(&needsbuffer, on, 476 on & ~VFS_BIO_NEED_BUFSPACE)) 477 break; 478 } 479 if (need_wakeup) 480 wakeup(__DEVOLATILE(void *, &needsbuffer)); 481 rw_runlock(&nblock); 482 } 483 484 /* 485 * runningwakeup: 486 * 487 * Wake up processes that are waiting on asynchronous writes to fall 488 * below lorunningspace. 489 */ 490 static void 491 runningwakeup(void) 492 { 493 494 mtx_lock(&rbreqlock); 495 if (runningbufreq) { 496 runningbufreq = 0; 497 wakeup(&runningbufreq); 498 } 499 mtx_unlock(&rbreqlock); 500 } 501 502 /* 503 * runningbufwakeup: 504 * 505 * Decrement the outstanding write count according. 506 */ 507 void 508 runningbufwakeup(struct buf *bp) 509 { 510 long space, bspace; 511 512 bspace = bp->b_runningbufspace; 513 if (bspace == 0) 514 return; 515 space = atomic_fetchadd_long(&runningbufspace, -bspace); 516 KASSERT(space >= bspace, ("runningbufspace underflow %ld %ld", 517 space, bspace)); 518 bp->b_runningbufspace = 0; 519 /* 520 * Only acquire the lock and wakeup on the transition from exceeding 521 * the threshold to falling below it. 522 */ 523 if (space < lorunningspace) 524 return; 525 if (space - bspace > lorunningspace) 526 return; 527 runningwakeup(); 528 } 529 530 /* 531 * bufcountadd: 532 * 533 * Called when a buffer has been added to one of the free queues to 534 * account for the buffer and to wakeup anyone waiting for free buffers. 535 * This typically occurs when large amounts of metadata are being handled 536 * by the buffer cache ( else buffer space runs out first, usually ). 537 */ 538 static __inline void 539 bufcountadd(struct buf *bp) 540 { 541 int mask, need_wakeup, old, on; 542 543 KASSERT((bp->b_flags & B_INFREECNT) == 0, 544 ("buf %p already counted as free", bp)); 545 bp->b_flags |= B_INFREECNT; 546 old = atomic_fetchadd_int(&numfreebuffers, 1); 547 KASSERT(old >= 0 && old < nbuf, 548 ("numfreebuffers climbed to %d", old + 1)); 549 mask = VFS_BIO_NEED_ANY; 550 if (numfreebuffers >= hifreebuffers) 551 mask |= VFS_BIO_NEED_FREE; 552 rw_rlock(&nblock); 553 for (;;) { 554 need_wakeup = 0; 555 on = needsbuffer; 556 if (on == 0) 557 break; 558 need_wakeup = 1; 559 if (atomic_cmpset_rel_int(&needsbuffer, on, on & ~mask)) 560 break; 561 } 562 if (need_wakeup) 563 wakeup(__DEVOLATILE(void *, &needsbuffer)); 564 rw_runlock(&nblock); 565 } 566 567 /* 568 * bufcountsub: 569 * 570 * Decrement the numfreebuffers count as needed. 571 */ 572 static void 573 bufcountsub(struct buf *bp) 574 { 575 int old; 576 577 /* 578 * Fixup numfreebuffers count. If the buffer is invalid or not 579 * delayed-write, the buffer was free and we must decrement 580 * numfreebuffers. 581 */ 582 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { 583 KASSERT((bp->b_flags & B_INFREECNT) != 0, 584 ("buf %p not counted in numfreebuffers", bp)); 585 bp->b_flags &= ~B_INFREECNT; 586 old = atomic_fetchadd_int(&numfreebuffers, -1); 587 KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1)); 588 } 589 } 590 591 /* 592 * waitrunningbufspace() 593 * 594 * runningbufspace is a measure of the amount of I/O currently 595 * running. This routine is used in async-write situations to 596 * prevent creating huge backups of pending writes to a device. 597 * Only asynchronous writes are governed by this function. 598 * 599 * This does NOT turn an async write into a sync write. It waits 600 * for earlier writes to complete and generally returns before the 601 * caller's write has reached the device. 602 */ 603 void 604 waitrunningbufspace(void) 605 { 606 607 mtx_lock(&rbreqlock); 608 while (runningbufspace > hirunningspace) { 609 runningbufreq = 1; 610 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 611 } 612 mtx_unlock(&rbreqlock); 613 } 614 615 616 /* 617 * vfs_buf_test_cache: 618 * 619 * Called when a buffer is extended. This function clears the B_CACHE 620 * bit if the newly extended portion of the buffer does not contain 621 * valid data. 622 */ 623 static __inline 624 void 625 vfs_buf_test_cache(struct buf *bp, 626 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 627 vm_page_t m) 628 { 629 630 VM_OBJECT_ASSERT_LOCKED(m->object); 631 if (bp->b_flags & B_CACHE) { 632 int base = (foff + off) & PAGE_MASK; 633 if (vm_page_is_valid(m, base, size) == 0) 634 bp->b_flags &= ~B_CACHE; 635 } 636 } 637 638 /* Wake up the buffer daemon if necessary */ 639 static __inline void 640 bd_wakeup(void) 641 { 642 643 mtx_lock(&bdlock); 644 if (bd_request == 0) { 645 bd_request = 1; 646 wakeup(&bd_request); 647 } 648 mtx_unlock(&bdlock); 649 } 650 651 /* 652 * bd_speedup - speedup the buffer cache flushing code 653 */ 654 void 655 bd_speedup(void) 656 { 657 int needwake; 658 659 mtx_lock(&bdlock); 660 needwake = 0; 661 if (bd_speedupreq == 0 || bd_request == 0) 662 needwake = 1; 663 bd_speedupreq = 1; 664 bd_request = 1; 665 if (needwake) 666 wakeup(&bd_request); 667 mtx_unlock(&bdlock); 668 } 669 670 #ifndef NSWBUF_MIN 671 #define NSWBUF_MIN 16 672 #endif 673 674 #ifdef __i386__ 675 #define TRANSIENT_DENOM 5 676 #else 677 #define TRANSIENT_DENOM 10 678 #endif 679 680 /* 681 * Calculating buffer cache scaling values and reserve space for buffer 682 * headers. This is called during low level kernel initialization and 683 * may be called more then once. We CANNOT write to the memory area 684 * being reserved at this time. 685 */ 686 caddr_t 687 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 688 { 689 int tuned_nbuf; 690 long maxbuf, maxbuf_sz, buf_sz, biotmap_sz; 691 692 /* 693 * physmem_est is in pages. Convert it to kilobytes (assumes 694 * PAGE_SIZE is >= 1K) 695 */ 696 physmem_est = physmem_est * (PAGE_SIZE / 1024); 697 698 /* 699 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 700 * For the first 64MB of ram nominally allocate sufficient buffers to 701 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 702 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing 703 * the buffer cache we limit the eventual kva reservation to 704 * maxbcache bytes. 705 * 706 * factor represents the 1/4 x ram conversion. 707 */ 708 if (nbuf == 0) { 709 int factor = 4 * BKVASIZE / 1024; 710 711 nbuf = 50; 712 if (physmem_est > 4096) 713 nbuf += min((physmem_est - 4096) / factor, 714 65536 / factor); 715 if (physmem_est > 65536) 716 nbuf += min((physmem_est - 65536) * 2 / (factor * 5), 717 32 * 1024 * 1024 / (factor * 5)); 718 719 if (maxbcache && nbuf > maxbcache / BKVASIZE) 720 nbuf = maxbcache / BKVASIZE; 721 tuned_nbuf = 1; 722 } else 723 tuned_nbuf = 0; 724 725 /* XXX Avoid unsigned long overflows later on with maxbufspace. */ 726 maxbuf = (LONG_MAX / 3) / BKVASIZE; 727 if (nbuf > maxbuf) { 728 if (!tuned_nbuf) 729 printf("Warning: nbufs lowered from %d to %ld\n", nbuf, 730 maxbuf); 731 nbuf = maxbuf; 732 } 733 734 /* 735 * Ideal allocation size for the transient bio submap is 10% 736 * of the maximal space buffer map. This roughly corresponds 737 * to the amount of the buffer mapped for typical UFS load. 738 * 739 * Clip the buffer map to reserve space for the transient 740 * BIOs, if its extent is bigger than 90% (80% on i386) of the 741 * maximum buffer map extent on the platform. 742 * 743 * The fall-back to the maxbuf in case of maxbcache unset, 744 * allows to not trim the buffer KVA for the architectures 745 * with ample KVA space. 746 */ 747 if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) { 748 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE; 749 buf_sz = (long)nbuf * BKVASIZE; 750 if (buf_sz < maxbuf_sz / TRANSIENT_DENOM * 751 (TRANSIENT_DENOM - 1)) { 752 /* 753 * There is more KVA than memory. Do not 754 * adjust buffer map size, and assign the rest 755 * of maxbuf to transient map. 756 */ 757 biotmap_sz = maxbuf_sz - buf_sz; 758 } else { 759 /* 760 * Buffer map spans all KVA we could afford on 761 * this platform. Give 10% (20% on i386) of 762 * the buffer map to the transient bio map. 763 */ 764 biotmap_sz = buf_sz / TRANSIENT_DENOM; 765 buf_sz -= biotmap_sz; 766 } 767 if (biotmap_sz / INT_MAX > MAXPHYS) 768 bio_transient_maxcnt = INT_MAX; 769 else 770 bio_transient_maxcnt = biotmap_sz / MAXPHYS; 771 /* 772 * Artifically limit to 1024 simultaneous in-flight I/Os 773 * using the transient mapping. 774 */ 775 if (bio_transient_maxcnt > 1024) 776 bio_transient_maxcnt = 1024; 777 if (tuned_nbuf) 778 nbuf = buf_sz / BKVASIZE; 779 } 780 781 /* 782 * swbufs are used as temporary holders for I/O, such as paging I/O. 783 * We have no less then 16 and no more then 256. 784 */ 785 nswbuf = min(nbuf / 4, 256); 786 TUNABLE_INT_FETCH("kern.nswbuf", &nswbuf); 787 if (nswbuf < NSWBUF_MIN) 788 nswbuf = NSWBUF_MIN; 789 790 /* 791 * Reserve space for the buffer cache buffers 792 */ 793 swbuf = (void *)v; 794 v = (caddr_t)(swbuf + nswbuf); 795 buf = (void *)v; 796 v = (caddr_t)(buf + nbuf); 797 798 return(v); 799 } 800 801 /* Initialize the buffer subsystem. Called before use of any buffers. */ 802 void 803 bufinit(void) 804 { 805 struct buf *bp; 806 int i; 807 808 CTASSERT(MAXBCACHEBUF >= MAXBSIZE); 809 mtx_init(&bqclean, "bufq clean lock", NULL, MTX_DEF); 810 mtx_init(&bqdirty, "bufq dirty lock", NULL, MTX_DEF); 811 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 812 rw_init(&nblock, "needsbuffer lock"); 813 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 814 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF); 815 816 /* next, make a null set of free lists */ 817 for (i = 0; i < BUFFER_QUEUES; i++) 818 TAILQ_INIT(&bufqueues[i]); 819 820 /* finally, initialize each buffer header and stick on empty q */ 821 for (i = 0; i < nbuf; i++) { 822 bp = &buf[i]; 823 bzero(bp, sizeof *bp); 824 bp->b_flags = B_INVAL | B_INFREECNT; 825 bp->b_rcred = NOCRED; 826 bp->b_wcred = NOCRED; 827 bp->b_qindex = QUEUE_EMPTY; 828 bp->b_xflags = 0; 829 LIST_INIT(&bp->b_dep); 830 BUF_LOCKINIT(bp); 831 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 832 #ifdef INVARIANTS 833 bq_len[QUEUE_EMPTY]++; 834 #endif 835 } 836 837 /* 838 * maxbufspace is the absolute maximum amount of buffer space we are 839 * allowed to reserve in KVM and in real terms. The absolute maximum 840 * is nominally used by buf_daemon. hibufspace is the nominal maximum 841 * used by most other processes. The differential is required to 842 * ensure that buf_daemon is able to run when other processes might 843 * be blocked waiting for buffer space. 844 * 845 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 846 * this may result in KVM fragmentation which is not handled optimally 847 * by the system. 848 */ 849 maxbufspace = (long)nbuf * BKVASIZE; 850 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - MAXBCACHEBUF * 10); 851 lobufspace = hibufspace - MAXBCACHEBUF; 852 853 /* 854 * Note: The 16 MiB upper limit for hirunningspace was chosen 855 * arbitrarily and may need further tuning. It corresponds to 856 * 128 outstanding write IO requests (if IO size is 128 KiB), 857 * which fits with many RAID controllers' tagged queuing limits. 858 * The lower 1 MiB limit is the historical upper limit for 859 * hirunningspace. 860 */ 861 hirunningspace = lmax(lmin(roundup(hibufspace / 64, MAXBCACHEBUF), 862 16 * 1024 * 1024), 1024 * 1024); 863 lorunningspace = roundup((hirunningspace * 2) / 3, MAXBCACHEBUF); 864 865 /* 866 * Limit the amount of malloc memory since it is wired permanently into 867 * the kernel space. Even though this is accounted for in the buffer 868 * allocation, we don't want the malloced region to grow uncontrolled. 869 * The malloc scheme improves memory utilization significantly on average 870 * (small) directories. 871 */ 872 maxbufmallocspace = hibufspace / 20; 873 874 /* 875 * Reduce the chance of a deadlock occuring by limiting the number 876 * of delayed-write dirty buffers we allow to stack up. 877 */ 878 hidirtybuffers = nbuf / 4 + 20; 879 dirtybufthresh = hidirtybuffers * 9 / 10; 880 numdirtybuffers = 0; 881 /* 882 * To support extreme low-memory systems, make sure hidirtybuffers cannot 883 * eat up all available buffer space. This occurs when our minimum cannot 884 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 885 * BKVASIZE'd buffers. 886 */ 887 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 888 hidirtybuffers >>= 1; 889 } 890 lodirtybuffers = hidirtybuffers / 2; 891 892 /* 893 * Try to keep the number of free buffers in the specified range, 894 * and give special processes (e.g. like buf_daemon) access to an 895 * emergency reserve. 896 */ 897 lofreebuffers = nbuf / 18 + 5; 898 hifreebuffers = 2 * lofreebuffers; 899 numfreebuffers = nbuf; 900 901 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ | 902 VM_ALLOC_NORMAL | VM_ALLOC_WIRED); 903 unmapped_buf = (caddr_t)kva_alloc(MAXPHYS); 904 } 905 906 #ifdef INVARIANTS 907 static inline void 908 vfs_buf_check_mapped(struct buf *bp) 909 { 910 911 KASSERT((bp->b_flags & B_UNMAPPED) == 0, 912 ("mapped buf %p %x", bp, bp->b_flags)); 913 KASSERT(bp->b_kvabase != unmapped_buf, 914 ("mapped buf: b_kvabase was not updated %p", bp)); 915 KASSERT(bp->b_data != unmapped_buf, 916 ("mapped buf: b_data was not updated %p", bp)); 917 } 918 919 static inline void 920 vfs_buf_check_unmapped(struct buf *bp) 921 { 922 923 KASSERT((bp->b_flags & B_UNMAPPED) == B_UNMAPPED, 924 ("unmapped buf %p %x", bp, bp->b_flags)); 925 KASSERT(bp->b_kvabase == unmapped_buf, 926 ("unmapped buf: corrupted b_kvabase %p", bp)); 927 KASSERT(bp->b_data == unmapped_buf, 928 ("unmapped buf: corrupted b_data %p", bp)); 929 } 930 931 #define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp) 932 #define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp) 933 #else 934 #define BUF_CHECK_MAPPED(bp) do {} while (0) 935 #define BUF_CHECK_UNMAPPED(bp) do {} while (0) 936 #endif 937 938 static void 939 bpmap_qenter(struct buf *bp) 940 { 941 942 BUF_CHECK_MAPPED(bp); 943 944 /* 945 * bp->b_data is relative to bp->b_offset, but 946 * bp->b_offset may be offset into the first page. 947 */ 948 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data); 949 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages); 950 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 951 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 952 } 953 954 /* 955 * bfreekva() - free the kva allocation for a buffer. 956 * 957 * Since this call frees up buffer space, we call bufspacewakeup(). 958 */ 959 static void 960 bfreekva(struct buf *bp) 961 { 962 963 if (bp->b_kvasize == 0) 964 return; 965 966 atomic_add_int(&buffreekvacnt, 1); 967 atomic_subtract_long(&bufspace, bp->b_kvasize); 968 if ((bp->b_flags & B_UNMAPPED) == 0) { 969 BUF_CHECK_MAPPED(bp); 970 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, 971 bp->b_kvasize); 972 } else { 973 BUF_CHECK_UNMAPPED(bp); 974 if ((bp->b_flags & B_KVAALLOC) != 0) { 975 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvaalloc, 976 bp->b_kvasize); 977 } 978 atomic_subtract_long(&unmapped_bufspace, bp->b_kvasize); 979 bp->b_flags &= ~(B_UNMAPPED | B_KVAALLOC); 980 } 981 bp->b_kvasize = 0; 982 bufspacewakeup(); 983 } 984 985 /* 986 * binsfree: 987 * 988 * Insert the buffer into the appropriate free list. 989 */ 990 static void 991 binsfree(struct buf *bp, int qindex) 992 { 993 struct mtx *olock, *nlock; 994 995 BUF_ASSERT_XLOCKED(bp); 996 997 nlock = bqlock(qindex); 998 /* Handle delayed bremfree() processing. */ 999 if (bp->b_flags & B_REMFREE) { 1000 olock = bqlock(bp->b_qindex); 1001 mtx_lock(olock); 1002 bremfreel(bp); 1003 if (olock != nlock) { 1004 mtx_unlock(olock); 1005 mtx_lock(nlock); 1006 } 1007 } else 1008 mtx_lock(nlock); 1009 1010 if (bp->b_qindex != QUEUE_NONE) 1011 panic("binsfree: free buffer onto another queue???"); 1012 1013 bp->b_qindex = qindex; 1014 if (bp->b_flags & B_AGE) 1015 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1016 else 1017 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1018 #ifdef INVARIANTS 1019 bq_len[bp->b_qindex]++; 1020 #endif 1021 mtx_unlock(nlock); 1022 1023 /* 1024 * Something we can maybe free or reuse. 1025 */ 1026 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1027 bufspacewakeup(); 1028 1029 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI)) 1030 bufcountadd(bp); 1031 } 1032 1033 /* 1034 * bremfree: 1035 * 1036 * Mark the buffer for removal from the appropriate free list. 1037 * 1038 */ 1039 void 1040 bremfree(struct buf *bp) 1041 { 1042 1043 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1044 KASSERT((bp->b_flags & B_REMFREE) == 0, 1045 ("bremfree: buffer %p already marked for delayed removal.", bp)); 1046 KASSERT(bp->b_qindex != QUEUE_NONE, 1047 ("bremfree: buffer %p not on a queue.", bp)); 1048 BUF_ASSERT_XLOCKED(bp); 1049 1050 bp->b_flags |= B_REMFREE; 1051 bufcountsub(bp); 1052 } 1053 1054 /* 1055 * bremfreef: 1056 * 1057 * Force an immediate removal from a free list. Used only in nfs when 1058 * it abuses the b_freelist pointer. 1059 */ 1060 void 1061 bremfreef(struct buf *bp) 1062 { 1063 struct mtx *qlock; 1064 1065 qlock = bqlock(bp->b_qindex); 1066 mtx_lock(qlock); 1067 bremfreel(bp); 1068 mtx_unlock(qlock); 1069 } 1070 1071 /* 1072 * bremfreel: 1073 * 1074 * Removes a buffer from the free list, must be called with the 1075 * correct qlock held. 1076 */ 1077 static void 1078 bremfreel(struct buf *bp) 1079 { 1080 1081 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X", 1082 bp, bp->b_vp, bp->b_flags); 1083 KASSERT(bp->b_qindex != QUEUE_NONE, 1084 ("bremfreel: buffer %p not on a queue.", bp)); 1085 BUF_ASSERT_XLOCKED(bp); 1086 mtx_assert(bqlock(bp->b_qindex), MA_OWNED); 1087 1088 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 1089 #ifdef INVARIANTS 1090 KASSERT(bq_len[bp->b_qindex] >= 1, ("queue %d underflow", 1091 bp->b_qindex)); 1092 bq_len[bp->b_qindex]--; 1093 #endif 1094 bp->b_qindex = QUEUE_NONE; 1095 /* 1096 * If this was a delayed bremfree() we only need to remove the buffer 1097 * from the queue and return the stats are already done. 1098 */ 1099 if (bp->b_flags & B_REMFREE) { 1100 bp->b_flags &= ~B_REMFREE; 1101 return; 1102 } 1103 bufcountsub(bp); 1104 } 1105 1106 /* 1107 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 1108 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 1109 * the buffer is valid and we do not have to do anything. 1110 */ 1111 void 1112 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, 1113 int cnt, struct ucred * cred) 1114 { 1115 struct buf *rabp; 1116 int i; 1117 1118 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 1119 if (inmem(vp, *rablkno)) 1120 continue; 1121 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 1122 1123 if ((rabp->b_flags & B_CACHE) == 0) { 1124 if (!TD_IS_IDLETHREAD(curthread)) 1125 curthread->td_ru.ru_inblock++; 1126 rabp->b_flags |= B_ASYNC; 1127 rabp->b_flags &= ~B_INVAL; 1128 rabp->b_ioflags &= ~BIO_ERROR; 1129 rabp->b_iocmd = BIO_READ; 1130 if (rabp->b_rcred == NOCRED && cred != NOCRED) 1131 rabp->b_rcred = crhold(cred); 1132 vfs_busy_pages(rabp, 0); 1133 BUF_KERNPROC(rabp); 1134 rabp->b_iooffset = dbtob(rabp->b_blkno); 1135 bstrategy(rabp); 1136 } else { 1137 brelse(rabp); 1138 } 1139 } 1140 } 1141 1142 /* 1143 * Entry point for bread() and breadn() via #defines in sys/buf.h. 1144 * 1145 * Get a buffer with the specified data. Look in the cache first. We 1146 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 1147 * is set, the buffer is valid and we do not have to do anything, see 1148 * getblk(). Also starts asynchronous I/O on read-ahead blocks. 1149 */ 1150 int 1151 breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno, 1152 int *rabsize, int cnt, struct ucred *cred, int flags, struct buf **bpp) 1153 { 1154 struct buf *bp; 1155 int rv = 0, readwait = 0; 1156 1157 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 1158 /* 1159 * Can only return NULL if GB_LOCK_NOWAIT flag is specified. 1160 */ 1161 *bpp = bp = getblk(vp, blkno, size, 0, 0, flags); 1162 if (bp == NULL) 1163 return (EBUSY); 1164 1165 /* if not found in cache, do some I/O */ 1166 if ((bp->b_flags & B_CACHE) == 0) { 1167 if (!TD_IS_IDLETHREAD(curthread)) 1168 curthread->td_ru.ru_inblock++; 1169 bp->b_iocmd = BIO_READ; 1170 bp->b_flags &= ~B_INVAL; 1171 bp->b_ioflags &= ~BIO_ERROR; 1172 if (bp->b_rcred == NOCRED && cred != NOCRED) 1173 bp->b_rcred = crhold(cred); 1174 vfs_busy_pages(bp, 0); 1175 bp->b_iooffset = dbtob(bp->b_blkno); 1176 bstrategy(bp); 1177 ++readwait; 1178 } 1179 1180 breada(vp, rablkno, rabsize, cnt, cred); 1181 1182 if (readwait) { 1183 rv = bufwait(bp); 1184 } 1185 return (rv); 1186 } 1187 1188 /* 1189 * Write, release buffer on completion. (Done by iodone 1190 * if async). Do not bother writing anything if the buffer 1191 * is invalid. 1192 * 1193 * Note that we set B_CACHE here, indicating that buffer is 1194 * fully valid and thus cacheable. This is true even of NFS 1195 * now so we set it generally. This could be set either here 1196 * or in biodone() since the I/O is synchronous. We put it 1197 * here. 1198 */ 1199 int 1200 bufwrite(struct buf *bp) 1201 { 1202 int oldflags; 1203 struct vnode *vp; 1204 long space; 1205 int vp_md; 1206 1207 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1208 if (bp->b_flags & B_INVAL) { 1209 brelse(bp); 1210 return (0); 1211 } 1212 1213 if (bp->b_flags & B_BARRIER) 1214 barrierwrites++; 1215 1216 oldflags = bp->b_flags; 1217 1218 BUF_ASSERT_HELD(bp); 1219 1220 if (bp->b_pin_count > 0) 1221 bunpin_wait(bp); 1222 1223 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 1224 ("FFS background buffer should not get here %p", bp)); 1225 1226 vp = bp->b_vp; 1227 if (vp) 1228 vp_md = vp->v_vflag & VV_MD; 1229 else 1230 vp_md = 0; 1231 1232 /* 1233 * Mark the buffer clean. Increment the bufobj write count 1234 * before bundirty() call, to prevent other thread from seeing 1235 * empty dirty list and zero counter for writes in progress, 1236 * falsely indicating that the bufobj is clean. 1237 */ 1238 bufobj_wref(bp->b_bufobj); 1239 bundirty(bp); 1240 1241 bp->b_flags &= ~B_DONE; 1242 bp->b_ioflags &= ~BIO_ERROR; 1243 bp->b_flags |= B_CACHE; 1244 bp->b_iocmd = BIO_WRITE; 1245 1246 vfs_busy_pages(bp, 1); 1247 1248 /* 1249 * Normal bwrites pipeline writes 1250 */ 1251 bp->b_runningbufspace = bp->b_bufsize; 1252 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace); 1253 1254 if (!TD_IS_IDLETHREAD(curthread)) 1255 curthread->td_ru.ru_oublock++; 1256 if (oldflags & B_ASYNC) 1257 BUF_KERNPROC(bp); 1258 bp->b_iooffset = dbtob(bp->b_blkno); 1259 bstrategy(bp); 1260 1261 if ((oldflags & B_ASYNC) == 0) { 1262 int rtval = bufwait(bp); 1263 brelse(bp); 1264 return (rtval); 1265 } else if (space > hirunningspace) { 1266 /* 1267 * don't allow the async write to saturate the I/O 1268 * system. We will not deadlock here because 1269 * we are blocking waiting for I/O that is already in-progress 1270 * to complete. We do not block here if it is the update 1271 * or syncer daemon trying to clean up as that can lead 1272 * to deadlock. 1273 */ 1274 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 1275 waitrunningbufspace(); 1276 } 1277 1278 return (0); 1279 } 1280 1281 void 1282 bufbdflush(struct bufobj *bo, struct buf *bp) 1283 { 1284 struct buf *nbp; 1285 1286 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 1287 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 1288 altbufferflushes++; 1289 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 1290 BO_LOCK(bo); 1291 /* 1292 * Try to find a buffer to flush. 1293 */ 1294 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 1295 if ((nbp->b_vflags & BV_BKGRDINPROG) || 1296 BUF_LOCK(nbp, 1297 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 1298 continue; 1299 if (bp == nbp) 1300 panic("bdwrite: found ourselves"); 1301 BO_UNLOCK(bo); 1302 /* Don't countdeps with the bo lock held. */ 1303 if (buf_countdeps(nbp, 0)) { 1304 BO_LOCK(bo); 1305 BUF_UNLOCK(nbp); 1306 continue; 1307 } 1308 if (nbp->b_flags & B_CLUSTEROK) { 1309 vfs_bio_awrite(nbp); 1310 } else { 1311 bremfree(nbp); 1312 bawrite(nbp); 1313 } 1314 dirtybufferflushes++; 1315 break; 1316 } 1317 if (nbp == NULL) 1318 BO_UNLOCK(bo); 1319 } 1320 } 1321 1322 /* 1323 * Delayed write. (Buffer is marked dirty). Do not bother writing 1324 * anything if the buffer is marked invalid. 1325 * 1326 * Note that since the buffer must be completely valid, we can safely 1327 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 1328 * biodone() in order to prevent getblk from writing the buffer 1329 * out synchronously. 1330 */ 1331 void 1332 bdwrite(struct buf *bp) 1333 { 1334 struct thread *td = curthread; 1335 struct vnode *vp; 1336 struct bufobj *bo; 1337 1338 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1339 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1340 KASSERT((bp->b_flags & B_BARRIER) == 0, 1341 ("Barrier request in delayed write %p", bp)); 1342 BUF_ASSERT_HELD(bp); 1343 1344 if (bp->b_flags & B_INVAL) { 1345 brelse(bp); 1346 return; 1347 } 1348 1349 /* 1350 * If we have too many dirty buffers, don't create any more. 1351 * If we are wildly over our limit, then force a complete 1352 * cleanup. Otherwise, just keep the situation from getting 1353 * out of control. Note that we have to avoid a recursive 1354 * disaster and not try to clean up after our own cleanup! 1355 */ 1356 vp = bp->b_vp; 1357 bo = bp->b_bufobj; 1358 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 1359 td->td_pflags |= TDP_INBDFLUSH; 1360 BO_BDFLUSH(bo, bp); 1361 td->td_pflags &= ~TDP_INBDFLUSH; 1362 } else 1363 recursiveflushes++; 1364 1365 bdirty(bp); 1366 /* 1367 * Set B_CACHE, indicating that the buffer is fully valid. This is 1368 * true even of NFS now. 1369 */ 1370 bp->b_flags |= B_CACHE; 1371 1372 /* 1373 * This bmap keeps the system from needing to do the bmap later, 1374 * perhaps when the system is attempting to do a sync. Since it 1375 * is likely that the indirect block -- or whatever other datastructure 1376 * that the filesystem needs is still in memory now, it is a good 1377 * thing to do this. Note also, that if the pageout daemon is 1378 * requesting a sync -- there might not be enough memory to do 1379 * the bmap then... So, this is important to do. 1380 */ 1381 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 1382 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 1383 } 1384 1385 /* 1386 * Set the *dirty* buffer range based upon the VM system dirty 1387 * pages. 1388 * 1389 * Mark the buffer pages as clean. We need to do this here to 1390 * satisfy the vnode_pager and the pageout daemon, so that it 1391 * thinks that the pages have been "cleaned". Note that since 1392 * the pages are in a delayed write buffer -- the VFS layer 1393 * "will" see that the pages get written out on the next sync, 1394 * or perhaps the cluster will be completed. 1395 */ 1396 vfs_clean_pages_dirty_buf(bp); 1397 bqrelse(bp); 1398 1399 /* 1400 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 1401 * due to the softdep code. 1402 */ 1403 } 1404 1405 /* 1406 * bdirty: 1407 * 1408 * Turn buffer into delayed write request. We must clear BIO_READ and 1409 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 1410 * itself to properly update it in the dirty/clean lists. We mark it 1411 * B_DONE to ensure that any asynchronization of the buffer properly 1412 * clears B_DONE ( else a panic will occur later ). 1413 * 1414 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 1415 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 1416 * should only be called if the buffer is known-good. 1417 * 1418 * Since the buffer is not on a queue, we do not update the numfreebuffers 1419 * count. 1420 * 1421 * The buffer must be on QUEUE_NONE. 1422 */ 1423 void 1424 bdirty(struct buf *bp) 1425 { 1426 1427 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 1428 bp, bp->b_vp, bp->b_flags); 1429 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1430 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1431 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1432 BUF_ASSERT_HELD(bp); 1433 bp->b_flags &= ~(B_RELBUF); 1434 bp->b_iocmd = BIO_WRITE; 1435 1436 if ((bp->b_flags & B_DELWRI) == 0) { 1437 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 1438 reassignbuf(bp); 1439 bdirtyadd(); 1440 } 1441 } 1442 1443 /* 1444 * bundirty: 1445 * 1446 * Clear B_DELWRI for buffer. 1447 * 1448 * Since the buffer is not on a queue, we do not update the numfreebuffers 1449 * count. 1450 * 1451 * The buffer must be on QUEUE_NONE. 1452 */ 1453 1454 void 1455 bundirty(struct buf *bp) 1456 { 1457 1458 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1459 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1460 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1461 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1462 BUF_ASSERT_HELD(bp); 1463 1464 if (bp->b_flags & B_DELWRI) { 1465 bp->b_flags &= ~B_DELWRI; 1466 reassignbuf(bp); 1467 bdirtysub(); 1468 } 1469 /* 1470 * Since it is now being written, we can clear its deferred write flag. 1471 */ 1472 bp->b_flags &= ~B_DEFERRED; 1473 } 1474 1475 /* 1476 * bawrite: 1477 * 1478 * Asynchronous write. Start output on a buffer, but do not wait for 1479 * it to complete. The buffer is released when the output completes. 1480 * 1481 * bwrite() ( or the VOP routine anyway ) is responsible for handling 1482 * B_INVAL buffers. Not us. 1483 */ 1484 void 1485 bawrite(struct buf *bp) 1486 { 1487 1488 bp->b_flags |= B_ASYNC; 1489 (void) bwrite(bp); 1490 } 1491 1492 /* 1493 * babarrierwrite: 1494 * 1495 * Asynchronous barrier write. Start output on a buffer, but do not 1496 * wait for it to complete. Place a write barrier after this write so 1497 * that this buffer and all buffers written before it are committed to 1498 * the disk before any buffers written after this write are committed 1499 * to the disk. The buffer is released when the output completes. 1500 */ 1501 void 1502 babarrierwrite(struct buf *bp) 1503 { 1504 1505 bp->b_flags |= B_ASYNC | B_BARRIER; 1506 (void) bwrite(bp); 1507 } 1508 1509 /* 1510 * bbarrierwrite: 1511 * 1512 * Synchronous barrier write. Start output on a buffer and wait for 1513 * it to complete. Place a write barrier after this write so that 1514 * this buffer and all buffers written before it are committed to 1515 * the disk before any buffers written after this write are committed 1516 * to the disk. The buffer is released when the output completes. 1517 */ 1518 int 1519 bbarrierwrite(struct buf *bp) 1520 { 1521 1522 bp->b_flags |= B_BARRIER; 1523 return (bwrite(bp)); 1524 } 1525 1526 /* 1527 * bwillwrite: 1528 * 1529 * Called prior to the locking of any vnodes when we are expecting to 1530 * write. We do not want to starve the buffer cache with too many 1531 * dirty buffers so we block here. By blocking prior to the locking 1532 * of any vnodes we attempt to avoid the situation where a locked vnode 1533 * prevents the various system daemons from flushing related buffers. 1534 */ 1535 void 1536 bwillwrite(void) 1537 { 1538 1539 if (numdirtybuffers >= hidirtybuffers) { 1540 mtx_lock(&bdirtylock); 1541 while (numdirtybuffers >= hidirtybuffers) { 1542 bdirtywait = 1; 1543 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4), 1544 "flswai", 0); 1545 } 1546 mtx_unlock(&bdirtylock); 1547 } 1548 } 1549 1550 /* 1551 * Return true if we have too many dirty buffers. 1552 */ 1553 int 1554 buf_dirty_count_severe(void) 1555 { 1556 1557 return(numdirtybuffers >= hidirtybuffers); 1558 } 1559 1560 static __noinline int 1561 buf_vm_page_count_severe(void) 1562 { 1563 1564 KFAIL_POINT_CODE(DEBUG_FP, buf_pressure, return 1); 1565 1566 return vm_page_count_severe(); 1567 } 1568 1569 /* 1570 * brelse: 1571 * 1572 * Release a busy buffer and, if requested, free its resources. The 1573 * buffer will be stashed in the appropriate bufqueue[] allowing it 1574 * to be accessed later as a cache entity or reused for other purposes. 1575 */ 1576 void 1577 brelse(struct buf *bp) 1578 { 1579 int qindex; 1580 1581 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 1582 bp, bp->b_vp, bp->b_flags); 1583 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1584 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1585 1586 if (BUF_LOCKRECURSED(bp)) { 1587 /* 1588 * Do not process, in particular, do not handle the 1589 * B_INVAL/B_RELBUF and do not release to free list. 1590 */ 1591 BUF_UNLOCK(bp); 1592 return; 1593 } 1594 1595 if (bp->b_flags & B_MANAGED) { 1596 bqrelse(bp); 1597 return; 1598 } 1599 1600 if ((bp->b_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) { 1601 BO_LOCK(bp->b_bufobj); 1602 bp->b_vflags &= ~BV_BKGRDERR; 1603 BO_UNLOCK(bp->b_bufobj); 1604 bdirty(bp); 1605 } 1606 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 1607 bp->b_error == EIO && !(bp->b_flags & B_INVAL)) { 1608 /* 1609 * Failed write, redirty. Must clear BIO_ERROR to prevent 1610 * pages from being scrapped. If the error is anything 1611 * other than an I/O error (EIO), assume that retrying 1612 * is futile. 1613 */ 1614 bp->b_ioflags &= ~BIO_ERROR; 1615 bdirty(bp); 1616 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 1617 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 1618 /* 1619 * Either a failed I/O or we were asked to free or not 1620 * cache the buffer. 1621 */ 1622 bp->b_flags |= B_INVAL; 1623 if (!LIST_EMPTY(&bp->b_dep)) 1624 buf_deallocate(bp); 1625 if (bp->b_flags & B_DELWRI) 1626 bdirtysub(); 1627 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1628 if ((bp->b_flags & B_VMIO) == 0) { 1629 if (bp->b_bufsize) 1630 allocbuf(bp, 0); 1631 if (bp->b_vp) 1632 brelvp(bp); 1633 } 1634 } 1635 1636 /* 1637 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1638 * is called with B_DELWRI set, the underlying pages may wind up 1639 * getting freed causing a previous write (bdwrite()) to get 'lost' 1640 * because pages associated with a B_DELWRI bp are marked clean. 1641 * 1642 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1643 * if B_DELWRI is set. 1644 * 1645 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1646 * on pages to return pages to the VM page queues. 1647 */ 1648 if (bp->b_flags & B_DELWRI) 1649 bp->b_flags &= ~B_RELBUF; 1650 else if (buf_vm_page_count_severe()) { 1651 /* 1652 * BKGRDINPROG can only be set with the buf and bufobj 1653 * locks both held. We tolerate a race to clear it here. 1654 */ 1655 if (!(bp->b_vflags & BV_BKGRDINPROG)) 1656 bp->b_flags |= B_RELBUF; 1657 } 1658 1659 /* 1660 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1661 * constituted, not even NFS buffers now. Two flags effect this. If 1662 * B_INVAL, the struct buf is invalidated but the VM object is kept 1663 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1664 * 1665 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 1666 * invalidated. BIO_ERROR cannot be set for a failed write unless the 1667 * buffer is also B_INVAL because it hits the re-dirtying code above. 1668 * 1669 * Normally we can do this whether a buffer is B_DELWRI or not. If 1670 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1671 * the commit state and we cannot afford to lose the buffer. If the 1672 * buffer has a background write in progress, we need to keep it 1673 * around to prevent it from being reconstituted and starting a second 1674 * background write. 1675 */ 1676 if ((bp->b_flags & B_VMIO) 1677 && !(bp->b_vp->v_mount != NULL && 1678 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 1679 !vn_isdisk(bp->b_vp, NULL) && 1680 (bp->b_flags & B_DELWRI)) 1681 ) { 1682 1683 int i, j, resid; 1684 vm_page_t m; 1685 off_t foff; 1686 vm_pindex_t poff; 1687 vm_object_t obj; 1688 1689 obj = bp->b_bufobj->bo_object; 1690 1691 /* 1692 * Get the base offset and length of the buffer. Note that 1693 * in the VMIO case if the buffer block size is not 1694 * page-aligned then b_data pointer may not be page-aligned. 1695 * But our b_pages[] array *IS* page aligned. 1696 * 1697 * block sizes less then DEV_BSIZE (usually 512) are not 1698 * supported due to the page granularity bits (m->valid, 1699 * m->dirty, etc...). 1700 * 1701 * See man buf(9) for more information 1702 */ 1703 resid = bp->b_bufsize; 1704 foff = bp->b_offset; 1705 for (i = 0; i < bp->b_npages; i++) { 1706 int had_bogus = 0; 1707 1708 m = bp->b_pages[i]; 1709 1710 /* 1711 * If we hit a bogus page, fixup *all* the bogus pages 1712 * now. 1713 */ 1714 if (m == bogus_page) { 1715 poff = OFF_TO_IDX(bp->b_offset); 1716 had_bogus = 1; 1717 1718 VM_OBJECT_RLOCK(obj); 1719 for (j = i; j < bp->b_npages; j++) { 1720 vm_page_t mtmp; 1721 mtmp = bp->b_pages[j]; 1722 if (mtmp == bogus_page) { 1723 mtmp = vm_page_lookup(obj, poff + j); 1724 if (!mtmp) { 1725 panic("brelse: page missing\n"); 1726 } 1727 bp->b_pages[j] = mtmp; 1728 } 1729 } 1730 VM_OBJECT_RUNLOCK(obj); 1731 1732 if ((bp->b_flags & (B_INVAL | B_UNMAPPED)) == 0) { 1733 BUF_CHECK_MAPPED(bp); 1734 pmap_qenter( 1735 trunc_page((vm_offset_t)bp->b_data), 1736 bp->b_pages, bp->b_npages); 1737 } 1738 m = bp->b_pages[i]; 1739 } 1740 if ((bp->b_flags & B_NOCACHE) || 1741 (bp->b_ioflags & BIO_ERROR && 1742 bp->b_iocmd == BIO_READ)) { 1743 int poffset = foff & PAGE_MASK; 1744 int presid = resid > (PAGE_SIZE - poffset) ? 1745 (PAGE_SIZE - poffset) : resid; 1746 1747 KASSERT(presid >= 0, ("brelse: extra page")); 1748 VM_OBJECT_WLOCK(obj); 1749 while (vm_page_xbusied(m)) { 1750 vm_page_lock(m); 1751 VM_OBJECT_WUNLOCK(obj); 1752 vm_page_busy_sleep(m, "mbncsh"); 1753 VM_OBJECT_WLOCK(obj); 1754 } 1755 if (pmap_page_wired_mappings(m) == 0) 1756 vm_page_set_invalid(m, poffset, presid); 1757 VM_OBJECT_WUNLOCK(obj); 1758 if (had_bogus) 1759 printf("avoided corruption bug in bogus_page/brelse code\n"); 1760 } 1761 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1762 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1763 } 1764 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1765 vfs_vmio_release(bp); 1766 1767 } else if (bp->b_flags & B_VMIO) { 1768 1769 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1770 vfs_vmio_release(bp); 1771 } 1772 1773 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) { 1774 if (bp->b_bufsize != 0) 1775 allocbuf(bp, 0); 1776 if (bp->b_vp != NULL) 1777 brelvp(bp); 1778 } 1779 1780 /* 1781 * If the buffer has junk contents signal it and eventually 1782 * clean up B_DELWRI and diassociate the vnode so that gbincore() 1783 * doesn't find it. 1784 */ 1785 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 1786 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 1787 bp->b_flags |= B_INVAL; 1788 if (bp->b_flags & B_INVAL) { 1789 if (bp->b_flags & B_DELWRI) 1790 bundirty(bp); 1791 if (bp->b_vp) 1792 brelvp(bp); 1793 } 1794 1795 /* buffers with no memory */ 1796 if (bp->b_bufsize == 0) { 1797 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1798 if (bp->b_vflags & BV_BKGRDINPROG) 1799 panic("losing buffer 1"); 1800 if (bp->b_kvasize) 1801 qindex = QUEUE_EMPTYKVA; 1802 else 1803 qindex = QUEUE_EMPTY; 1804 bp->b_flags |= B_AGE; 1805 /* buffers with junk contents */ 1806 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 1807 (bp->b_ioflags & BIO_ERROR)) { 1808 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1809 if (bp->b_vflags & BV_BKGRDINPROG) 1810 panic("losing buffer 2"); 1811 qindex = QUEUE_CLEAN; 1812 bp->b_flags |= B_AGE; 1813 /* remaining buffers */ 1814 } else if (bp->b_flags & B_DELWRI) 1815 qindex = QUEUE_DIRTY; 1816 else 1817 qindex = QUEUE_CLEAN; 1818 1819 binsfree(bp, qindex); 1820 1821 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 1822 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1823 panic("brelse: not dirty"); 1824 /* unlock */ 1825 BUF_UNLOCK(bp); 1826 } 1827 1828 /* 1829 * Release a buffer back to the appropriate queue but do not try to free 1830 * it. The buffer is expected to be used again soon. 1831 * 1832 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1833 * biodone() to requeue an async I/O on completion. It is also used when 1834 * known good buffers need to be requeued but we think we may need the data 1835 * again soon. 1836 * 1837 * XXX we should be able to leave the B_RELBUF hint set on completion. 1838 */ 1839 void 1840 bqrelse(struct buf *bp) 1841 { 1842 int qindex; 1843 1844 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1845 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1846 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1847 1848 if (BUF_LOCKRECURSED(bp)) { 1849 /* do not release to free list */ 1850 BUF_UNLOCK(bp); 1851 return; 1852 } 1853 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1854 1855 if (bp->b_flags & B_MANAGED) { 1856 if (bp->b_flags & B_REMFREE) 1857 bremfreef(bp); 1858 goto out; 1859 } 1860 1861 /* buffers with stale but valid contents */ 1862 if ((bp->b_flags & B_DELWRI) != 0 || (bp->b_vflags & (BV_BKGRDINPROG | 1863 BV_BKGRDERR)) == BV_BKGRDERR) { 1864 BO_LOCK(bp->b_bufobj); 1865 bp->b_vflags &= ~BV_BKGRDERR; 1866 BO_UNLOCK(bp->b_bufobj); 1867 qindex = QUEUE_DIRTY; 1868 } else { 1869 if ((bp->b_flags & B_DELWRI) == 0 && 1870 (bp->b_xflags & BX_VNDIRTY)) 1871 panic("bqrelse: not dirty"); 1872 /* 1873 * BKGRDINPROG can only be set with the buf and bufobj 1874 * locks both held. We tolerate a race to clear it here. 1875 */ 1876 if (buf_vm_page_count_severe() && 1877 (bp->b_vflags & BV_BKGRDINPROG) == 0) { 1878 /* 1879 * We are too low on memory, we have to try to free 1880 * the buffer (most importantly: the wired pages 1881 * making up its backing store) *now*. 1882 */ 1883 brelse(bp); 1884 return; 1885 } 1886 qindex = QUEUE_CLEAN; 1887 } 1888 binsfree(bp, qindex); 1889 1890 out: 1891 /* unlock */ 1892 BUF_UNLOCK(bp); 1893 } 1894 1895 /* Give pages used by the bp back to the VM system (where possible) */ 1896 static void 1897 vfs_vmio_release(struct buf *bp) 1898 { 1899 vm_object_t obj; 1900 vm_page_t m; 1901 int i; 1902 1903 if ((bp->b_flags & B_UNMAPPED) == 0) { 1904 BUF_CHECK_MAPPED(bp); 1905 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages); 1906 } else 1907 BUF_CHECK_UNMAPPED(bp); 1908 obj = bp->b_bufobj->bo_object; 1909 if (obj != NULL) 1910 VM_OBJECT_WLOCK(obj); 1911 for (i = 0; i < bp->b_npages; i++) { 1912 m = bp->b_pages[i]; 1913 bp->b_pages[i] = NULL; 1914 /* 1915 * In order to keep page LRU ordering consistent, put 1916 * everything on the inactive queue. 1917 */ 1918 vm_page_lock(m); 1919 vm_page_unwire(m, PQ_INACTIVE); 1920 1921 /* 1922 * Might as well free the page if we can and it has 1923 * no valid data. We also free the page if the 1924 * buffer was used for direct I/O 1925 */ 1926 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid) { 1927 if (m->wire_count == 0 && !vm_page_busied(m)) 1928 vm_page_free(m); 1929 } else if (bp->b_flags & B_DIRECT) 1930 vm_page_try_to_free(m); 1931 else if (buf_vm_page_count_severe()) 1932 vm_page_try_to_cache(m); 1933 vm_page_unlock(m); 1934 } 1935 if (obj != NULL) 1936 VM_OBJECT_WUNLOCK(obj); 1937 1938 if (bp->b_bufsize) { 1939 bufspacewakeup(); 1940 bp->b_bufsize = 0; 1941 } 1942 bp->b_npages = 0; 1943 bp->b_flags &= ~B_VMIO; 1944 if (bp->b_vp) 1945 brelvp(bp); 1946 } 1947 1948 /* 1949 * Check to see if a block at a particular lbn is available for a clustered 1950 * write. 1951 */ 1952 static int 1953 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 1954 { 1955 struct buf *bpa; 1956 int match; 1957 1958 match = 0; 1959 1960 /* If the buf isn't in core skip it */ 1961 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 1962 return (0); 1963 1964 /* If the buf is busy we don't want to wait for it */ 1965 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1966 return (0); 1967 1968 /* Only cluster with valid clusterable delayed write buffers */ 1969 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 1970 (B_DELWRI | B_CLUSTEROK)) 1971 goto done; 1972 1973 if (bpa->b_bufsize != size) 1974 goto done; 1975 1976 /* 1977 * Check to see if it is in the expected place on disk and that the 1978 * block has been mapped. 1979 */ 1980 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 1981 match = 1; 1982 done: 1983 BUF_UNLOCK(bpa); 1984 return (match); 1985 } 1986 1987 /* 1988 * vfs_bio_awrite: 1989 * 1990 * Implement clustered async writes for clearing out B_DELWRI buffers. 1991 * This is much better then the old way of writing only one buffer at 1992 * a time. Note that we may not be presented with the buffers in the 1993 * correct order, so we search for the cluster in both directions. 1994 */ 1995 int 1996 vfs_bio_awrite(struct buf *bp) 1997 { 1998 struct bufobj *bo; 1999 int i; 2000 int j; 2001 daddr_t lblkno = bp->b_lblkno; 2002 struct vnode *vp = bp->b_vp; 2003 int ncl; 2004 int nwritten; 2005 int size; 2006 int maxcl; 2007 int gbflags; 2008 2009 bo = &vp->v_bufobj; 2010 gbflags = (bp->b_flags & B_UNMAPPED) != 0 ? GB_UNMAPPED : 0; 2011 /* 2012 * right now we support clustered writing only to regular files. If 2013 * we find a clusterable block we could be in the middle of a cluster 2014 * rather then at the beginning. 2015 */ 2016 if ((vp->v_type == VREG) && 2017 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 2018 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 2019 2020 size = vp->v_mount->mnt_stat.f_iosize; 2021 maxcl = MAXPHYS / size; 2022 2023 BO_RLOCK(bo); 2024 for (i = 1; i < maxcl; i++) 2025 if (vfs_bio_clcheck(vp, size, lblkno + i, 2026 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 2027 break; 2028 2029 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 2030 if (vfs_bio_clcheck(vp, size, lblkno - j, 2031 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 2032 break; 2033 BO_RUNLOCK(bo); 2034 --j; 2035 ncl = i + j; 2036 /* 2037 * this is a possible cluster write 2038 */ 2039 if (ncl != 1) { 2040 BUF_UNLOCK(bp); 2041 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl, 2042 gbflags); 2043 return (nwritten); 2044 } 2045 } 2046 bremfree(bp); 2047 bp->b_flags |= B_ASYNC; 2048 /* 2049 * default (old) behavior, writing out only one block 2050 * 2051 * XXX returns b_bufsize instead of b_bcount for nwritten? 2052 */ 2053 nwritten = bp->b_bufsize; 2054 (void) bwrite(bp); 2055 2056 return (nwritten); 2057 } 2058 2059 static void 2060 setbufkva(struct buf *bp, vm_offset_t addr, int maxsize, int gbflags) 2061 { 2062 2063 KASSERT((bp->b_flags & (B_UNMAPPED | B_KVAALLOC)) == 0 && 2064 bp->b_kvasize == 0, ("call bfreekva(%p)", bp)); 2065 if ((gbflags & GB_UNMAPPED) == 0) { 2066 bp->b_kvabase = (caddr_t)addr; 2067 } else if ((gbflags & GB_KVAALLOC) != 0) { 2068 KASSERT((gbflags & GB_UNMAPPED) != 0, 2069 ("GB_KVAALLOC without GB_UNMAPPED")); 2070 bp->b_kvaalloc = (caddr_t)addr; 2071 bp->b_flags |= B_UNMAPPED | B_KVAALLOC; 2072 atomic_add_long(&unmapped_bufspace, bp->b_kvasize); 2073 } 2074 bp->b_kvasize = maxsize; 2075 } 2076 2077 /* 2078 * Allocate the buffer KVA and set b_kvasize. Also set b_kvabase if 2079 * needed. 2080 */ 2081 static int 2082 allocbufkva(struct buf *bp, int maxsize, int gbflags) 2083 { 2084 vm_offset_t addr; 2085 2086 bfreekva(bp); 2087 addr = 0; 2088 2089 if (vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr)) { 2090 /* 2091 * Buffer map is too fragmented. Request the caller 2092 * to defragment the map. 2093 */ 2094 atomic_add_int(&bufdefragcnt, 1); 2095 return (1); 2096 } 2097 setbufkva(bp, addr, maxsize, gbflags); 2098 atomic_add_long(&bufspace, bp->b_kvasize); 2099 return (0); 2100 } 2101 2102 /* 2103 * Ask the bufdaemon for help, or act as bufdaemon itself, when a 2104 * locked vnode is supplied. 2105 */ 2106 static void 2107 getnewbuf_bufd_help(struct vnode *vp, int gbflags, int slpflag, int slptimeo, 2108 int defrag) 2109 { 2110 struct thread *td; 2111 char *waitmsg; 2112 int error, fl, flags, norunbuf; 2113 2114 mtx_assert(&bqclean, MA_OWNED); 2115 2116 if (defrag) { 2117 flags = VFS_BIO_NEED_BUFSPACE; 2118 waitmsg = "nbufkv"; 2119 } else if (bufspace >= hibufspace) { 2120 waitmsg = "nbufbs"; 2121 flags = VFS_BIO_NEED_BUFSPACE; 2122 } else { 2123 waitmsg = "newbuf"; 2124 flags = VFS_BIO_NEED_ANY; 2125 } 2126 atomic_set_int(&needsbuffer, flags); 2127 mtx_unlock(&bqclean); 2128 2129 bd_speedup(); /* heeeelp */ 2130 if ((gbflags & GB_NOWAIT_BD) != 0) 2131 return; 2132 2133 td = curthread; 2134 rw_wlock(&nblock); 2135 while ((needsbuffer & flags) != 0) { 2136 if (vp != NULL && vp->v_type != VCHR && 2137 (td->td_pflags & TDP_BUFNEED) == 0) { 2138 rw_wunlock(&nblock); 2139 /* 2140 * getblk() is called with a vnode locked, and 2141 * some majority of the dirty buffers may as 2142 * well belong to the vnode. Flushing the 2143 * buffers there would make a progress that 2144 * cannot be achieved by the buf_daemon, that 2145 * cannot lock the vnode. 2146 */ 2147 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) | 2148 (td->td_pflags & TDP_NORUNNINGBUF); 2149 2150 /* 2151 * Play bufdaemon. The getnewbuf() function 2152 * may be called while the thread owns lock 2153 * for another dirty buffer for the same 2154 * vnode, which makes it impossible to use 2155 * VOP_FSYNC() there, due to the buffer lock 2156 * recursion. 2157 */ 2158 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF; 2159 fl = buf_flush(vp, flushbufqtarget); 2160 td->td_pflags &= norunbuf; 2161 rw_wlock(&nblock); 2162 if (fl != 0) 2163 continue; 2164 if ((needsbuffer & flags) == 0) 2165 break; 2166 } 2167 error = rw_sleep(__DEVOLATILE(void *, &needsbuffer), &nblock, 2168 (PRIBIO + 4) | slpflag, waitmsg, slptimeo); 2169 if (error != 0) 2170 break; 2171 } 2172 rw_wunlock(&nblock); 2173 } 2174 2175 static void 2176 getnewbuf_reuse_bp(struct buf *bp, int qindex) 2177 { 2178 2179 CTR6(KTR_BUF, "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d " 2180 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags, 2181 bp->b_kvasize, bp->b_bufsize, qindex); 2182 mtx_assert(&bqclean, MA_NOTOWNED); 2183 2184 /* 2185 * Note: we no longer distinguish between VMIO and non-VMIO 2186 * buffers. 2187 */ 2188 KASSERT((bp->b_flags & B_DELWRI) == 0, 2189 ("delwri buffer %p found in queue %d", bp, qindex)); 2190 2191 if (qindex == QUEUE_CLEAN) { 2192 if (bp->b_flags & B_VMIO) { 2193 bp->b_flags &= ~B_ASYNC; 2194 vfs_vmio_release(bp); 2195 } 2196 if (bp->b_vp != NULL) 2197 brelvp(bp); 2198 } 2199 2200 /* 2201 * Get the rest of the buffer freed up. b_kva* is still valid 2202 * after this operation. 2203 */ 2204 2205 if (bp->b_rcred != NOCRED) { 2206 crfree(bp->b_rcred); 2207 bp->b_rcred = NOCRED; 2208 } 2209 if (bp->b_wcred != NOCRED) { 2210 crfree(bp->b_wcred); 2211 bp->b_wcred = NOCRED; 2212 } 2213 if (!LIST_EMPTY(&bp->b_dep)) 2214 buf_deallocate(bp); 2215 if (bp->b_vflags & BV_BKGRDINPROG) 2216 panic("losing buffer 3"); 2217 KASSERT(bp->b_vp == NULL, ("bp: %p still has vnode %p. qindex: %d", 2218 bp, bp->b_vp, qindex)); 2219 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 2220 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags)); 2221 2222 if (bp->b_bufsize) 2223 allocbuf(bp, 0); 2224 2225 bp->b_flags &= B_UNMAPPED | B_KVAALLOC; 2226 bp->b_ioflags = 0; 2227 bp->b_xflags = 0; 2228 KASSERT((bp->b_flags & B_INFREECNT) == 0, 2229 ("buf %p still counted as free?", bp)); 2230 bp->b_vflags = 0; 2231 bp->b_vp = NULL; 2232 bp->b_blkno = bp->b_lblkno = 0; 2233 bp->b_offset = NOOFFSET; 2234 bp->b_iodone = 0; 2235 bp->b_error = 0; 2236 bp->b_resid = 0; 2237 bp->b_bcount = 0; 2238 bp->b_npages = 0; 2239 bp->b_dirtyoff = bp->b_dirtyend = 0; 2240 bp->b_bufobj = NULL; 2241 bp->b_pin_count = 0; 2242 bp->b_fsprivate1 = NULL; 2243 bp->b_fsprivate2 = NULL; 2244 bp->b_fsprivate3 = NULL; 2245 2246 LIST_INIT(&bp->b_dep); 2247 } 2248 2249 static int flushingbufs; 2250 2251 static struct buf * 2252 getnewbuf_scan(int maxsize, int defrag, int unmapped, int metadata) 2253 { 2254 struct buf *bp, *nbp; 2255 int nqindex, qindex, pass; 2256 2257 KASSERT(!unmapped || !defrag, ("both unmapped and defrag")); 2258 2259 pass = 1; 2260 restart: 2261 atomic_add_int(&getnewbufrestarts, 1); 2262 2263 /* 2264 * Setup for scan. If we do not have enough free buffers, 2265 * we setup a degenerate case that immediately fails. Note 2266 * that if we are specially marked process, we are allowed to 2267 * dip into our reserves. 2268 * 2269 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 2270 * for the allocation of the mapped buffer. For unmapped, the 2271 * easiest is to start with EMPTY outright. 2272 * 2273 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 2274 * However, there are a number of cases (defragging, reusing, ...) 2275 * where we cannot backup. 2276 */ 2277 nbp = NULL; 2278 mtx_lock(&bqclean); 2279 if (!defrag && unmapped) { 2280 nqindex = QUEUE_EMPTY; 2281 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 2282 } 2283 if (nbp == NULL) { 2284 nqindex = QUEUE_EMPTYKVA; 2285 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 2286 } 2287 2288 /* 2289 * If no EMPTYKVA buffers and we are either defragging or 2290 * reusing, locate a CLEAN buffer to free or reuse. If 2291 * bufspace useage is low skip this step so we can allocate a 2292 * new buffer. 2293 */ 2294 if (nbp == NULL && (defrag || bufspace >= lobufspace)) { 2295 nqindex = QUEUE_CLEAN; 2296 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2297 } 2298 2299 /* 2300 * If we could not find or were not allowed to reuse a CLEAN 2301 * buffer, check to see if it is ok to use an EMPTY buffer. 2302 * We can only use an EMPTY buffer if allocating its KVA would 2303 * not otherwise run us out of buffer space. No KVA is needed 2304 * for the unmapped allocation. 2305 */ 2306 if (nbp == NULL && defrag == 0 && (bufspace + maxsize < hibufspace || 2307 metadata)) { 2308 nqindex = QUEUE_EMPTY; 2309 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 2310 } 2311 2312 /* 2313 * All available buffers might be clean, retry ignoring the 2314 * lobufspace as the last resort. 2315 */ 2316 if (nbp == NULL && !TAILQ_EMPTY(&bufqueues[QUEUE_CLEAN])) { 2317 nqindex = QUEUE_CLEAN; 2318 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2319 } 2320 2321 /* 2322 * Run scan, possibly freeing data and/or kva mappings on the fly 2323 * depending. 2324 */ 2325 while ((bp = nbp) != NULL) { 2326 qindex = nqindex; 2327 2328 /* 2329 * Calculate next bp (we can only use it if we do not 2330 * block or do other fancy things). 2331 */ 2332 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 2333 switch (qindex) { 2334 case QUEUE_EMPTY: 2335 nqindex = QUEUE_EMPTYKVA; 2336 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 2337 if (nbp != NULL) 2338 break; 2339 /* FALLTHROUGH */ 2340 case QUEUE_EMPTYKVA: 2341 nqindex = QUEUE_CLEAN; 2342 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2343 if (nbp != NULL) 2344 break; 2345 /* FALLTHROUGH */ 2346 case QUEUE_CLEAN: 2347 if (metadata && pass == 1) { 2348 pass = 2; 2349 nqindex = QUEUE_EMPTY; 2350 nbp = TAILQ_FIRST( 2351 &bufqueues[QUEUE_EMPTY]); 2352 } 2353 /* 2354 * nbp is NULL. 2355 */ 2356 break; 2357 } 2358 } 2359 /* 2360 * If we are defragging then we need a buffer with 2361 * b_kvasize != 0. XXX this situation should no longer 2362 * occur, if defrag is non-zero the buffer's b_kvasize 2363 * should also be non-zero at this point. XXX 2364 */ 2365 if (defrag && bp->b_kvasize == 0) { 2366 printf("Warning: defrag empty buffer %p\n", bp); 2367 continue; 2368 } 2369 2370 /* 2371 * Start freeing the bp. This is somewhat involved. nbp 2372 * remains valid only for QUEUE_EMPTY[KVA] bp's. 2373 */ 2374 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2375 continue; 2376 /* 2377 * BKGRDINPROG can only be set with the buf and bufobj 2378 * locks both held. We tolerate a race to clear it here. 2379 */ 2380 if (bp->b_vflags & BV_BKGRDINPROG) { 2381 BUF_UNLOCK(bp); 2382 continue; 2383 } 2384 2385 /* 2386 * Requeue the background write buffer with error. 2387 */ 2388 if ((bp->b_vflags & BV_BKGRDERR) != 0) { 2389 bremfreel(bp); 2390 mtx_unlock(&bqclean); 2391 bqrelse(bp); 2392 continue; 2393 } 2394 2395 KASSERT(bp->b_qindex == qindex, 2396 ("getnewbuf: inconsistent queue %d bp %p", qindex, bp)); 2397 2398 bremfreel(bp); 2399 mtx_unlock(&bqclean); 2400 /* 2401 * NOTE: nbp is now entirely invalid. We can only restart 2402 * the scan from this point on. 2403 */ 2404 2405 getnewbuf_reuse_bp(bp, qindex); 2406 mtx_assert(&bqclean, MA_NOTOWNED); 2407 2408 /* 2409 * If we are defragging then free the buffer. 2410 */ 2411 if (defrag) { 2412 bp->b_flags |= B_INVAL; 2413 bfreekva(bp); 2414 brelse(bp); 2415 defrag = 0; 2416 goto restart; 2417 } 2418 2419 /* 2420 * Notify any waiters for the buffer lock about 2421 * identity change by freeing the buffer. 2422 */ 2423 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp)) { 2424 bp->b_flags |= B_INVAL; 2425 bfreekva(bp); 2426 brelse(bp); 2427 goto restart; 2428 } 2429 2430 if (metadata) 2431 break; 2432 2433 /* 2434 * If we are overcomitted then recover the buffer and its 2435 * KVM space. This occurs in rare situations when multiple 2436 * processes are blocked in getnewbuf() or allocbuf(). 2437 */ 2438 if (bufspace >= hibufspace) 2439 flushingbufs = 1; 2440 if (flushingbufs && bp->b_kvasize != 0) { 2441 bp->b_flags |= B_INVAL; 2442 bfreekva(bp); 2443 brelse(bp); 2444 goto restart; 2445 } 2446 if (bufspace < lobufspace) 2447 flushingbufs = 0; 2448 break; 2449 } 2450 return (bp); 2451 } 2452 2453 /* 2454 * getnewbuf: 2455 * 2456 * Find and initialize a new buffer header, freeing up existing buffers 2457 * in the bufqueues as necessary. The new buffer is returned locked. 2458 * 2459 * Important: B_INVAL is not set. If the caller wishes to throw the 2460 * buffer away, the caller must set B_INVAL prior to calling brelse(). 2461 * 2462 * We block if: 2463 * We have insufficient buffer headers 2464 * We have insufficient buffer space 2465 * buffer_arena is too fragmented ( space reservation fails ) 2466 * If we have to flush dirty buffers ( but we try to avoid this ) 2467 */ 2468 static struct buf * 2469 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int size, int maxsize, 2470 int gbflags) 2471 { 2472 struct buf *bp; 2473 int defrag, metadata; 2474 2475 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 2476 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 2477 if (!unmapped_buf_allowed) 2478 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC); 2479 2480 defrag = 0; 2481 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 || 2482 vp->v_type == VCHR) 2483 metadata = 1; 2484 else 2485 metadata = 0; 2486 /* 2487 * We can't afford to block since we might be holding a vnode lock, 2488 * which may prevent system daemons from running. We deal with 2489 * low-memory situations by proactively returning memory and running 2490 * async I/O rather then sync I/O. 2491 */ 2492 atomic_add_int(&getnewbufcalls, 1); 2493 atomic_subtract_int(&getnewbufrestarts, 1); 2494 restart: 2495 bp = getnewbuf_scan(maxsize, defrag, (gbflags & (GB_UNMAPPED | 2496 GB_KVAALLOC)) == GB_UNMAPPED, metadata); 2497 if (bp != NULL) 2498 defrag = 0; 2499 2500 /* 2501 * If we exhausted our list, sleep as appropriate. We may have to 2502 * wakeup various daemons and write out some dirty buffers. 2503 * 2504 * Generally we are sleeping due to insufficient buffer space. 2505 */ 2506 if (bp == NULL) { 2507 mtx_assert(&bqclean, MA_OWNED); 2508 getnewbuf_bufd_help(vp, gbflags, slpflag, slptimeo, defrag); 2509 mtx_assert(&bqclean, MA_NOTOWNED); 2510 } else if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == GB_UNMAPPED) { 2511 mtx_assert(&bqclean, MA_NOTOWNED); 2512 2513 bfreekva(bp); 2514 bp->b_flags |= B_UNMAPPED; 2515 bp->b_kvabase = bp->b_data = unmapped_buf; 2516 bp->b_kvasize = maxsize; 2517 atomic_add_long(&bufspace, bp->b_kvasize); 2518 atomic_add_long(&unmapped_bufspace, bp->b_kvasize); 2519 atomic_add_int(&bufreusecnt, 1); 2520 } else { 2521 mtx_assert(&bqclean, MA_NOTOWNED); 2522 2523 /* 2524 * We finally have a valid bp. We aren't quite out of the 2525 * woods, we still have to reserve kva space. In order 2526 * to keep fragmentation sane we only allocate kva in 2527 * BKVASIZE chunks. 2528 */ 2529 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2530 2531 if (maxsize != bp->b_kvasize || (bp->b_flags & (B_UNMAPPED | 2532 B_KVAALLOC)) == B_UNMAPPED) { 2533 if (allocbufkva(bp, maxsize, gbflags)) { 2534 defrag = 1; 2535 bp->b_flags |= B_INVAL; 2536 brelse(bp); 2537 goto restart; 2538 } 2539 atomic_add_int(&bufreusecnt, 1); 2540 } else if ((bp->b_flags & B_KVAALLOC) != 0 && 2541 (gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == 0) { 2542 /* 2543 * If the reused buffer has KVA allocated, 2544 * reassign b_kvaalloc to b_kvabase. 2545 */ 2546 bp->b_kvabase = bp->b_kvaalloc; 2547 bp->b_flags &= ~B_KVAALLOC; 2548 atomic_subtract_long(&unmapped_bufspace, 2549 bp->b_kvasize); 2550 atomic_add_int(&bufreusecnt, 1); 2551 } else if ((bp->b_flags & (B_UNMAPPED | B_KVAALLOC)) == 0 && 2552 (gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == (GB_UNMAPPED | 2553 GB_KVAALLOC)) { 2554 /* 2555 * The case of reused buffer already have KVA 2556 * mapped, but the request is for unmapped 2557 * buffer with KVA allocated. 2558 */ 2559 bp->b_kvaalloc = bp->b_kvabase; 2560 bp->b_data = bp->b_kvabase = unmapped_buf; 2561 bp->b_flags |= B_UNMAPPED | B_KVAALLOC; 2562 atomic_add_long(&unmapped_bufspace, 2563 bp->b_kvasize); 2564 atomic_add_int(&bufreusecnt, 1); 2565 } 2566 if ((gbflags & GB_UNMAPPED) == 0) { 2567 bp->b_saveaddr = bp->b_kvabase; 2568 bp->b_data = bp->b_saveaddr; 2569 bp->b_flags &= ~B_UNMAPPED; 2570 BUF_CHECK_MAPPED(bp); 2571 } 2572 } 2573 return (bp); 2574 } 2575 2576 /* 2577 * buf_daemon: 2578 * 2579 * buffer flushing daemon. Buffers are normally flushed by the 2580 * update daemon but if it cannot keep up this process starts to 2581 * take the load in an attempt to prevent getnewbuf() from blocking. 2582 */ 2583 2584 static struct kproc_desc buf_kp = { 2585 "bufdaemon", 2586 buf_daemon, 2587 &bufdaemonproc 2588 }; 2589 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 2590 2591 static int 2592 buf_flush(struct vnode *vp, int target) 2593 { 2594 int flushed; 2595 2596 flushed = flushbufqueues(vp, target, 0); 2597 if (flushed == 0) { 2598 /* 2599 * Could not find any buffers without rollback 2600 * dependencies, so just write the first one 2601 * in the hopes of eventually making progress. 2602 */ 2603 if (vp != NULL && target > 2) 2604 target /= 2; 2605 flushbufqueues(vp, target, 1); 2606 } 2607 return (flushed); 2608 } 2609 2610 static void 2611 buf_daemon() 2612 { 2613 int lodirty; 2614 2615 /* 2616 * This process needs to be suspended prior to shutdown sync. 2617 */ 2618 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2619 SHUTDOWN_PRI_LAST); 2620 2621 /* 2622 * This process is allowed to take the buffer cache to the limit 2623 */ 2624 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 2625 mtx_lock(&bdlock); 2626 for (;;) { 2627 bd_request = 0; 2628 mtx_unlock(&bdlock); 2629 2630 kproc_suspend_check(bufdaemonproc); 2631 lodirty = lodirtybuffers; 2632 if (bd_speedupreq) { 2633 lodirty = numdirtybuffers / 2; 2634 bd_speedupreq = 0; 2635 } 2636 /* 2637 * Do the flush. Limit the amount of in-transit I/O we 2638 * allow to build up, otherwise we would completely saturate 2639 * the I/O system. 2640 */ 2641 while (numdirtybuffers > lodirty) { 2642 if (buf_flush(NULL, numdirtybuffers - lodirty) == 0) 2643 break; 2644 kern_yield(PRI_USER); 2645 } 2646 2647 /* 2648 * Only clear bd_request if we have reached our low water 2649 * mark. The buf_daemon normally waits 1 second and 2650 * then incrementally flushes any dirty buffers that have 2651 * built up, within reason. 2652 * 2653 * If we were unable to hit our low water mark and couldn't 2654 * find any flushable buffers, we sleep for a short period 2655 * to avoid endless loops on unlockable buffers. 2656 */ 2657 mtx_lock(&bdlock); 2658 if (numdirtybuffers <= lodirtybuffers) { 2659 /* 2660 * We reached our low water mark, reset the 2661 * request and sleep until we are needed again. 2662 * The sleep is just so the suspend code works. 2663 */ 2664 bd_request = 0; 2665 /* 2666 * Do an extra wakeup in case dirty threshold 2667 * changed via sysctl and the explicit transition 2668 * out of shortfall was missed. 2669 */ 2670 bdirtywakeup(); 2671 if (runningbufspace <= lorunningspace) 2672 runningwakeup(); 2673 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 2674 } else { 2675 /* 2676 * We couldn't find any flushable dirty buffers but 2677 * still have too many dirty buffers, we 2678 * have to sleep and try again. (rare) 2679 */ 2680 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 2681 } 2682 } 2683 } 2684 2685 /* 2686 * flushbufqueues: 2687 * 2688 * Try to flush a buffer in the dirty queue. We must be careful to 2689 * free up B_INVAL buffers instead of write them, which NFS is 2690 * particularly sensitive to. 2691 */ 2692 static int flushwithdeps = 0; 2693 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 2694 0, "Number of buffers flushed with dependecies that require rollbacks"); 2695 2696 static int 2697 flushbufqueues(struct vnode *lvp, int target, int flushdeps) 2698 { 2699 struct buf *sentinel; 2700 struct vnode *vp; 2701 struct mount *mp; 2702 struct buf *bp; 2703 int hasdeps; 2704 int flushed; 2705 int queue; 2706 int error; 2707 bool unlock; 2708 2709 flushed = 0; 2710 queue = QUEUE_DIRTY; 2711 bp = NULL; 2712 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 2713 sentinel->b_qindex = QUEUE_SENTINEL; 2714 mtx_lock(&bqdirty); 2715 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist); 2716 mtx_unlock(&bqdirty); 2717 while (flushed != target) { 2718 maybe_yield(); 2719 mtx_lock(&bqdirty); 2720 bp = TAILQ_NEXT(sentinel, b_freelist); 2721 if (bp != NULL) { 2722 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2723 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel, 2724 b_freelist); 2725 } else { 2726 mtx_unlock(&bqdirty); 2727 break; 2728 } 2729 /* 2730 * Skip sentinels inserted by other invocations of the 2731 * flushbufqueues(), taking care to not reorder them. 2732 * 2733 * Only flush the buffers that belong to the 2734 * vnode locked by the curthread. 2735 */ 2736 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL && 2737 bp->b_vp != lvp)) { 2738 mtx_unlock(&bqdirty); 2739 continue; 2740 } 2741 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL); 2742 mtx_unlock(&bqdirty); 2743 if (error != 0) 2744 continue; 2745 if (bp->b_pin_count > 0) { 2746 BUF_UNLOCK(bp); 2747 continue; 2748 } 2749 /* 2750 * BKGRDINPROG can only be set with the buf and bufobj 2751 * locks both held. We tolerate a race to clear it here. 2752 */ 2753 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 2754 (bp->b_flags & B_DELWRI) == 0) { 2755 BUF_UNLOCK(bp); 2756 continue; 2757 } 2758 if (bp->b_flags & B_INVAL) { 2759 bremfreef(bp); 2760 brelse(bp); 2761 flushed++; 2762 continue; 2763 } 2764 2765 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 2766 if (flushdeps == 0) { 2767 BUF_UNLOCK(bp); 2768 continue; 2769 } 2770 hasdeps = 1; 2771 } else 2772 hasdeps = 0; 2773 /* 2774 * We must hold the lock on a vnode before writing 2775 * one of its buffers. Otherwise we may confuse, or 2776 * in the case of a snapshot vnode, deadlock the 2777 * system. 2778 * 2779 * The lock order here is the reverse of the normal 2780 * of vnode followed by buf lock. This is ok because 2781 * the NOWAIT will prevent deadlock. 2782 */ 2783 vp = bp->b_vp; 2784 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 2785 BUF_UNLOCK(bp); 2786 continue; 2787 } 2788 if (lvp == NULL) { 2789 unlock = true; 2790 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT); 2791 } else { 2792 ASSERT_VOP_LOCKED(vp, "getbuf"); 2793 unlock = false; 2794 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 : 2795 vn_lock(vp, LK_TRYUPGRADE); 2796 } 2797 if (error == 0) { 2798 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 2799 bp, bp->b_vp, bp->b_flags); 2800 if (curproc == bufdaemonproc) { 2801 vfs_bio_awrite(bp); 2802 } else { 2803 bremfree(bp); 2804 bwrite(bp); 2805 notbufdflushes++; 2806 } 2807 vn_finished_write(mp); 2808 if (unlock) 2809 VOP_UNLOCK(vp, 0); 2810 flushwithdeps += hasdeps; 2811 flushed++; 2812 2813 /* 2814 * Sleeping on runningbufspace while holding 2815 * vnode lock leads to deadlock. 2816 */ 2817 if (curproc == bufdaemonproc && 2818 runningbufspace > hirunningspace) 2819 waitrunningbufspace(); 2820 continue; 2821 } 2822 vn_finished_write(mp); 2823 BUF_UNLOCK(bp); 2824 } 2825 mtx_lock(&bqdirty); 2826 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2827 mtx_unlock(&bqdirty); 2828 free(sentinel, M_TEMP); 2829 return (flushed); 2830 } 2831 2832 /* 2833 * Check to see if a block is currently memory resident. 2834 */ 2835 struct buf * 2836 incore(struct bufobj *bo, daddr_t blkno) 2837 { 2838 struct buf *bp; 2839 2840 BO_RLOCK(bo); 2841 bp = gbincore(bo, blkno); 2842 BO_RUNLOCK(bo); 2843 return (bp); 2844 } 2845 2846 /* 2847 * Returns true if no I/O is needed to access the 2848 * associated VM object. This is like incore except 2849 * it also hunts around in the VM system for the data. 2850 */ 2851 2852 static int 2853 inmem(struct vnode * vp, daddr_t blkno) 2854 { 2855 vm_object_t obj; 2856 vm_offset_t toff, tinc, size; 2857 vm_page_t m; 2858 vm_ooffset_t off; 2859 2860 ASSERT_VOP_LOCKED(vp, "inmem"); 2861 2862 if (incore(&vp->v_bufobj, blkno)) 2863 return 1; 2864 if (vp->v_mount == NULL) 2865 return 0; 2866 obj = vp->v_object; 2867 if (obj == NULL) 2868 return (0); 2869 2870 size = PAGE_SIZE; 2871 if (size > vp->v_mount->mnt_stat.f_iosize) 2872 size = vp->v_mount->mnt_stat.f_iosize; 2873 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2874 2875 VM_OBJECT_RLOCK(obj); 2876 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2877 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2878 if (!m) 2879 goto notinmem; 2880 tinc = size; 2881 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2882 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2883 if (vm_page_is_valid(m, 2884 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2885 goto notinmem; 2886 } 2887 VM_OBJECT_RUNLOCK(obj); 2888 return 1; 2889 2890 notinmem: 2891 VM_OBJECT_RUNLOCK(obj); 2892 return (0); 2893 } 2894 2895 /* 2896 * Set the dirty range for a buffer based on the status of the dirty 2897 * bits in the pages comprising the buffer. The range is limited 2898 * to the size of the buffer. 2899 * 2900 * Tell the VM system that the pages associated with this buffer 2901 * are clean. This is used for delayed writes where the data is 2902 * going to go to disk eventually without additional VM intevention. 2903 * 2904 * Note that while we only really need to clean through to b_bcount, we 2905 * just go ahead and clean through to b_bufsize. 2906 */ 2907 static void 2908 vfs_clean_pages_dirty_buf(struct buf *bp) 2909 { 2910 vm_ooffset_t foff, noff, eoff; 2911 vm_page_t m; 2912 int i; 2913 2914 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 2915 return; 2916 2917 foff = bp->b_offset; 2918 KASSERT(bp->b_offset != NOOFFSET, 2919 ("vfs_clean_pages_dirty_buf: no buffer offset")); 2920 2921 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 2922 vfs_drain_busy_pages(bp); 2923 vfs_setdirty_locked_object(bp); 2924 for (i = 0; i < bp->b_npages; i++) { 2925 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2926 eoff = noff; 2927 if (eoff > bp->b_offset + bp->b_bufsize) 2928 eoff = bp->b_offset + bp->b_bufsize; 2929 m = bp->b_pages[i]; 2930 vfs_page_set_validclean(bp, foff, m); 2931 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 2932 foff = noff; 2933 } 2934 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 2935 } 2936 2937 static void 2938 vfs_setdirty_locked_object(struct buf *bp) 2939 { 2940 vm_object_t object; 2941 int i; 2942 2943 object = bp->b_bufobj->bo_object; 2944 VM_OBJECT_ASSERT_WLOCKED(object); 2945 2946 /* 2947 * We qualify the scan for modified pages on whether the 2948 * object has been flushed yet. 2949 */ 2950 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) { 2951 vm_offset_t boffset; 2952 vm_offset_t eoffset; 2953 2954 /* 2955 * test the pages to see if they have been modified directly 2956 * by users through the VM system. 2957 */ 2958 for (i = 0; i < bp->b_npages; i++) 2959 vm_page_test_dirty(bp->b_pages[i]); 2960 2961 /* 2962 * Calculate the encompassing dirty range, boffset and eoffset, 2963 * (eoffset - boffset) bytes. 2964 */ 2965 2966 for (i = 0; i < bp->b_npages; i++) { 2967 if (bp->b_pages[i]->dirty) 2968 break; 2969 } 2970 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2971 2972 for (i = bp->b_npages - 1; i >= 0; --i) { 2973 if (bp->b_pages[i]->dirty) { 2974 break; 2975 } 2976 } 2977 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2978 2979 /* 2980 * Fit it to the buffer. 2981 */ 2982 2983 if (eoffset > bp->b_bcount) 2984 eoffset = bp->b_bcount; 2985 2986 /* 2987 * If we have a good dirty range, merge with the existing 2988 * dirty range. 2989 */ 2990 2991 if (boffset < eoffset) { 2992 if (bp->b_dirtyoff > boffset) 2993 bp->b_dirtyoff = boffset; 2994 if (bp->b_dirtyend < eoffset) 2995 bp->b_dirtyend = eoffset; 2996 } 2997 } 2998 } 2999 3000 /* 3001 * Allocate the KVA mapping for an existing buffer. It handles the 3002 * cases of both B_UNMAPPED buffer, and buffer with the preallocated 3003 * KVA which is not mapped (B_KVAALLOC). 3004 */ 3005 static void 3006 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags) 3007 { 3008 struct buf *scratch_bp; 3009 int bsize, maxsize, need_mapping, need_kva; 3010 off_t offset; 3011 3012 need_mapping = (bp->b_flags & B_UNMAPPED) != 0 && 3013 (gbflags & GB_UNMAPPED) == 0; 3014 need_kva = (bp->b_flags & (B_KVAALLOC | B_UNMAPPED)) == B_UNMAPPED && 3015 (gbflags & GB_KVAALLOC) != 0; 3016 if (!need_mapping && !need_kva) 3017 return; 3018 3019 BUF_CHECK_UNMAPPED(bp); 3020 3021 if (need_mapping && (bp->b_flags & B_KVAALLOC) != 0) { 3022 /* 3023 * Buffer is not mapped, but the KVA was already 3024 * reserved at the time of the instantiation. Use the 3025 * allocated space. 3026 */ 3027 bp->b_flags &= ~B_KVAALLOC; 3028 KASSERT(bp->b_kvaalloc != 0, ("kvaalloc == 0")); 3029 bp->b_kvabase = bp->b_kvaalloc; 3030 atomic_subtract_long(&unmapped_bufspace, bp->b_kvasize); 3031 goto has_addr; 3032 } 3033 3034 /* 3035 * Calculate the amount of the address space we would reserve 3036 * if the buffer was mapped. 3037 */ 3038 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize; 3039 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3040 offset = blkno * bsize; 3041 maxsize = size + (offset & PAGE_MASK); 3042 maxsize = imax(maxsize, bsize); 3043 3044 mapping_loop: 3045 if (allocbufkva(bp, maxsize, gbflags)) { 3046 /* 3047 * Request defragmentation. getnewbuf() returns us the 3048 * allocated space by the scratch buffer KVA. 3049 */ 3050 scratch_bp = getnewbuf(bp->b_vp, 0, 0, size, maxsize, gbflags | 3051 (GB_UNMAPPED | GB_KVAALLOC)); 3052 if (scratch_bp == NULL) { 3053 if ((gbflags & GB_NOWAIT_BD) != 0) { 3054 /* 3055 * XXXKIB: defragmentation cannot 3056 * succeed, not sure what else to do. 3057 */ 3058 panic("GB_NOWAIT_BD and B_UNMAPPED %p", bp); 3059 } 3060 atomic_add_int(&mappingrestarts, 1); 3061 goto mapping_loop; 3062 } 3063 KASSERT((scratch_bp->b_flags & B_KVAALLOC) != 0, 3064 ("scratch bp !B_KVAALLOC %p", scratch_bp)); 3065 setbufkva(bp, (vm_offset_t)scratch_bp->b_kvaalloc, 3066 scratch_bp->b_kvasize, gbflags); 3067 3068 /* Get rid of the scratch buffer. */ 3069 scratch_bp->b_kvasize = 0; 3070 scratch_bp->b_flags |= B_INVAL; 3071 scratch_bp->b_flags &= ~(B_UNMAPPED | B_KVAALLOC); 3072 brelse(scratch_bp); 3073 } 3074 if (!need_mapping) 3075 return; 3076 3077 has_addr: 3078 bp->b_saveaddr = bp->b_kvabase; 3079 bp->b_data = bp->b_saveaddr; /* b_offset is handled by bpmap_qenter */ 3080 bp->b_flags &= ~B_UNMAPPED; 3081 BUF_CHECK_MAPPED(bp); 3082 bpmap_qenter(bp); 3083 } 3084 3085 /* 3086 * getblk: 3087 * 3088 * Get a block given a specified block and offset into a file/device. 3089 * The buffers B_DONE bit will be cleared on return, making it almost 3090 * ready for an I/O initiation. B_INVAL may or may not be set on 3091 * return. The caller should clear B_INVAL prior to initiating a 3092 * READ. 3093 * 3094 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 3095 * an existing buffer. 3096 * 3097 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 3098 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 3099 * and then cleared based on the backing VM. If the previous buffer is 3100 * non-0-sized but invalid, B_CACHE will be cleared. 3101 * 3102 * If getblk() must create a new buffer, the new buffer is returned with 3103 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 3104 * case it is returned with B_INVAL clear and B_CACHE set based on the 3105 * backing VM. 3106 * 3107 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 3108 * B_CACHE bit is clear. 3109 * 3110 * What this means, basically, is that the caller should use B_CACHE to 3111 * determine whether the buffer is fully valid or not and should clear 3112 * B_INVAL prior to issuing a read. If the caller intends to validate 3113 * the buffer by loading its data area with something, the caller needs 3114 * to clear B_INVAL. If the caller does this without issuing an I/O, 3115 * the caller should set B_CACHE ( as an optimization ), else the caller 3116 * should issue the I/O and biodone() will set B_CACHE if the I/O was 3117 * a write attempt or if it was a successfull read. If the caller 3118 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 3119 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 3120 */ 3121 struct buf * 3122 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3123 int flags) 3124 { 3125 struct buf *bp; 3126 struct bufobj *bo; 3127 int bsize, error, maxsize, vmio; 3128 off_t offset; 3129 3130 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 3131 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3132 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3133 ASSERT_VOP_LOCKED(vp, "getblk"); 3134 if (size > MAXBCACHEBUF) 3135 panic("getblk: size(%d) > MAXBCACHEBUF(%d)\n", size, 3136 MAXBCACHEBUF); 3137 if (!unmapped_buf_allowed) 3138 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3139 3140 bo = &vp->v_bufobj; 3141 loop: 3142 BO_RLOCK(bo); 3143 bp = gbincore(bo, blkno); 3144 if (bp != NULL) { 3145 int lockflags; 3146 /* 3147 * Buffer is in-core. If the buffer is not busy nor managed, 3148 * it must be on a queue. 3149 */ 3150 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 3151 3152 if (flags & GB_LOCK_NOWAIT) 3153 lockflags |= LK_NOWAIT; 3154 3155 error = BUF_TIMELOCK(bp, lockflags, 3156 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo); 3157 3158 /* 3159 * If we slept and got the lock we have to restart in case 3160 * the buffer changed identities. 3161 */ 3162 if (error == ENOLCK) 3163 goto loop; 3164 /* We timed out or were interrupted. */ 3165 else if (error) 3166 return (NULL); 3167 /* If recursed, assume caller knows the rules. */ 3168 else if (BUF_LOCKRECURSED(bp)) 3169 goto end; 3170 3171 /* 3172 * The buffer is locked. B_CACHE is cleared if the buffer is 3173 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 3174 * and for a VMIO buffer B_CACHE is adjusted according to the 3175 * backing VM cache. 3176 */ 3177 if (bp->b_flags & B_INVAL) 3178 bp->b_flags &= ~B_CACHE; 3179 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 3180 bp->b_flags |= B_CACHE; 3181 if (bp->b_flags & B_MANAGED) 3182 MPASS(bp->b_qindex == QUEUE_NONE); 3183 else 3184 bremfree(bp); 3185 3186 /* 3187 * check for size inconsistencies for non-VMIO case. 3188 */ 3189 if (bp->b_bcount != size) { 3190 if ((bp->b_flags & B_VMIO) == 0 || 3191 (size > bp->b_kvasize)) { 3192 if (bp->b_flags & B_DELWRI) { 3193 /* 3194 * If buffer is pinned and caller does 3195 * not want sleep waiting for it to be 3196 * unpinned, bail out 3197 * */ 3198 if (bp->b_pin_count > 0) { 3199 if (flags & GB_LOCK_NOWAIT) { 3200 bqrelse(bp); 3201 return (NULL); 3202 } else { 3203 bunpin_wait(bp); 3204 } 3205 } 3206 bp->b_flags |= B_NOCACHE; 3207 bwrite(bp); 3208 } else { 3209 if (LIST_EMPTY(&bp->b_dep)) { 3210 bp->b_flags |= B_RELBUF; 3211 brelse(bp); 3212 } else { 3213 bp->b_flags |= B_NOCACHE; 3214 bwrite(bp); 3215 } 3216 } 3217 goto loop; 3218 } 3219 } 3220 3221 /* 3222 * Handle the case of unmapped buffer which should 3223 * become mapped, or the buffer for which KVA 3224 * reservation is requested. 3225 */ 3226 bp_unmapped_get_kva(bp, blkno, size, flags); 3227 3228 /* 3229 * If the size is inconsistant in the VMIO case, we can resize 3230 * the buffer. This might lead to B_CACHE getting set or 3231 * cleared. If the size has not changed, B_CACHE remains 3232 * unchanged from its previous state. 3233 */ 3234 if (bp->b_bcount != size) 3235 allocbuf(bp, size); 3236 3237 KASSERT(bp->b_offset != NOOFFSET, 3238 ("getblk: no buffer offset")); 3239 3240 /* 3241 * A buffer with B_DELWRI set and B_CACHE clear must 3242 * be committed before we can return the buffer in 3243 * order to prevent the caller from issuing a read 3244 * ( due to B_CACHE not being set ) and overwriting 3245 * it. 3246 * 3247 * Most callers, including NFS and FFS, need this to 3248 * operate properly either because they assume they 3249 * can issue a read if B_CACHE is not set, or because 3250 * ( for example ) an uncached B_DELWRI might loop due 3251 * to softupdates re-dirtying the buffer. In the latter 3252 * case, B_CACHE is set after the first write completes, 3253 * preventing further loops. 3254 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 3255 * above while extending the buffer, we cannot allow the 3256 * buffer to remain with B_CACHE set after the write 3257 * completes or it will represent a corrupt state. To 3258 * deal with this we set B_NOCACHE to scrap the buffer 3259 * after the write. 3260 * 3261 * We might be able to do something fancy, like setting 3262 * B_CACHE in bwrite() except if B_DELWRI is already set, 3263 * so the below call doesn't set B_CACHE, but that gets real 3264 * confusing. This is much easier. 3265 */ 3266 3267 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 3268 bp->b_flags |= B_NOCACHE; 3269 bwrite(bp); 3270 goto loop; 3271 } 3272 bp->b_flags &= ~B_DONE; 3273 } else { 3274 /* 3275 * Buffer is not in-core, create new buffer. The buffer 3276 * returned by getnewbuf() is locked. Note that the returned 3277 * buffer is also considered valid (not marked B_INVAL). 3278 */ 3279 BO_RUNLOCK(bo); 3280 /* 3281 * If the user does not want us to create the buffer, bail out 3282 * here. 3283 */ 3284 if (flags & GB_NOCREAT) 3285 return NULL; 3286 if (numfreebuffers == 0 && TD_IS_IDLETHREAD(curthread)) 3287 return NULL; 3288 3289 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize; 3290 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3291 offset = blkno * bsize; 3292 vmio = vp->v_object != NULL; 3293 if (vmio) { 3294 maxsize = size + (offset & PAGE_MASK); 3295 } else { 3296 maxsize = size; 3297 /* Do not allow non-VMIO notmapped buffers. */ 3298 flags &= ~GB_UNMAPPED; 3299 } 3300 maxsize = imax(maxsize, bsize); 3301 3302 bp = getnewbuf(vp, slpflag, slptimeo, size, maxsize, flags); 3303 if (bp == NULL) { 3304 if (slpflag || slptimeo) 3305 return NULL; 3306 goto loop; 3307 } 3308 3309 /* 3310 * This code is used to make sure that a buffer is not 3311 * created while the getnewbuf routine is blocked. 3312 * This can be a problem whether the vnode is locked or not. 3313 * If the buffer is created out from under us, we have to 3314 * throw away the one we just created. 3315 * 3316 * Note: this must occur before we associate the buffer 3317 * with the vp especially considering limitations in 3318 * the splay tree implementation when dealing with duplicate 3319 * lblkno's. 3320 */ 3321 BO_LOCK(bo); 3322 if (gbincore(bo, blkno)) { 3323 BO_UNLOCK(bo); 3324 bp->b_flags |= B_INVAL; 3325 brelse(bp); 3326 goto loop; 3327 } 3328 3329 /* 3330 * Insert the buffer into the hash, so that it can 3331 * be found by incore. 3332 */ 3333 bp->b_blkno = bp->b_lblkno = blkno; 3334 bp->b_offset = offset; 3335 bgetvp(vp, bp); 3336 BO_UNLOCK(bo); 3337 3338 /* 3339 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 3340 * buffer size starts out as 0, B_CACHE will be set by 3341 * allocbuf() for the VMIO case prior to it testing the 3342 * backing store for validity. 3343 */ 3344 3345 if (vmio) { 3346 bp->b_flags |= B_VMIO; 3347 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 3348 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 3349 bp, vp->v_object, bp->b_bufobj->bo_object)); 3350 } else { 3351 bp->b_flags &= ~B_VMIO; 3352 KASSERT(bp->b_bufobj->bo_object == NULL, 3353 ("ARGH! has b_bufobj->bo_object %p %p\n", 3354 bp, bp->b_bufobj->bo_object)); 3355 BUF_CHECK_MAPPED(bp); 3356 } 3357 3358 allocbuf(bp, size); 3359 bp->b_flags &= ~B_DONE; 3360 } 3361 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 3362 BUF_ASSERT_HELD(bp); 3363 end: 3364 KASSERT(bp->b_bufobj == bo, 3365 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 3366 return (bp); 3367 } 3368 3369 /* 3370 * Get an empty, disassociated buffer of given size. The buffer is initially 3371 * set to B_INVAL. 3372 */ 3373 struct buf * 3374 geteblk(int size, int flags) 3375 { 3376 struct buf *bp; 3377 int maxsize; 3378 3379 maxsize = (size + BKVAMASK) & ~BKVAMASK; 3380 while ((bp = getnewbuf(NULL, 0, 0, size, maxsize, flags)) == NULL) { 3381 if ((flags & GB_NOWAIT_BD) && 3382 (curthread->td_pflags & TDP_BUFNEED) != 0) 3383 return (NULL); 3384 } 3385 allocbuf(bp, size); 3386 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 3387 BUF_ASSERT_HELD(bp); 3388 return (bp); 3389 } 3390 3391 3392 /* 3393 * This code constitutes the buffer memory from either anonymous system 3394 * memory (in the case of non-VMIO operations) or from an associated 3395 * VM object (in the case of VMIO operations). This code is able to 3396 * resize a buffer up or down. 3397 * 3398 * Note that this code is tricky, and has many complications to resolve 3399 * deadlock or inconsistant data situations. Tread lightly!!! 3400 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 3401 * the caller. Calling this code willy nilly can result in the loss of data. 3402 * 3403 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 3404 * B_CACHE for the non-VMIO case. 3405 */ 3406 3407 int 3408 allocbuf(struct buf *bp, int size) 3409 { 3410 int newbsize, mbsize; 3411 int i; 3412 3413 BUF_ASSERT_HELD(bp); 3414 3415 if (bp->b_kvasize < size) 3416 panic("allocbuf: buffer too small"); 3417 3418 if ((bp->b_flags & B_VMIO) == 0) { 3419 caddr_t origbuf; 3420 int origbufsize; 3421 /* 3422 * Just get anonymous memory from the kernel. Don't 3423 * mess with B_CACHE. 3424 */ 3425 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3426 if (bp->b_flags & B_MALLOC) 3427 newbsize = mbsize; 3428 else 3429 newbsize = round_page(size); 3430 3431 if (newbsize < bp->b_bufsize) { 3432 /* 3433 * malloced buffers are not shrunk 3434 */ 3435 if (bp->b_flags & B_MALLOC) { 3436 if (newbsize) { 3437 bp->b_bcount = size; 3438 } else { 3439 free(bp->b_data, M_BIOBUF); 3440 if (bp->b_bufsize) { 3441 atomic_subtract_long( 3442 &bufmallocspace, 3443 bp->b_bufsize); 3444 bufspacewakeup(); 3445 bp->b_bufsize = 0; 3446 } 3447 bp->b_saveaddr = bp->b_kvabase; 3448 bp->b_data = bp->b_saveaddr; 3449 bp->b_bcount = 0; 3450 bp->b_flags &= ~B_MALLOC; 3451 } 3452 return 1; 3453 } 3454 vm_hold_free_pages(bp, newbsize); 3455 } else if (newbsize > bp->b_bufsize) { 3456 /* 3457 * We only use malloced memory on the first allocation. 3458 * and revert to page-allocated memory when the buffer 3459 * grows. 3460 */ 3461 /* 3462 * There is a potential smp race here that could lead 3463 * to bufmallocspace slightly passing the max. It 3464 * is probably extremely rare and not worth worrying 3465 * over. 3466 */ 3467 if ( (bufmallocspace < maxbufmallocspace) && 3468 (bp->b_bufsize == 0) && 3469 (mbsize <= PAGE_SIZE/2)) { 3470 3471 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 3472 bp->b_bufsize = mbsize; 3473 bp->b_bcount = size; 3474 bp->b_flags |= B_MALLOC; 3475 atomic_add_long(&bufmallocspace, mbsize); 3476 return 1; 3477 } 3478 origbuf = NULL; 3479 origbufsize = 0; 3480 /* 3481 * If the buffer is growing on its other-than-first allocation, 3482 * then we revert to the page-allocation scheme. 3483 */ 3484 if (bp->b_flags & B_MALLOC) { 3485 origbuf = bp->b_data; 3486 origbufsize = bp->b_bufsize; 3487 bp->b_data = bp->b_kvabase; 3488 if (bp->b_bufsize) { 3489 atomic_subtract_long(&bufmallocspace, 3490 bp->b_bufsize); 3491 bufspacewakeup(); 3492 bp->b_bufsize = 0; 3493 } 3494 bp->b_flags &= ~B_MALLOC; 3495 newbsize = round_page(newbsize); 3496 } 3497 vm_hold_load_pages( 3498 bp, 3499 (vm_offset_t) bp->b_data + bp->b_bufsize, 3500 (vm_offset_t) bp->b_data + newbsize); 3501 if (origbuf) { 3502 bcopy(origbuf, bp->b_data, origbufsize); 3503 free(origbuf, M_BIOBUF); 3504 } 3505 } 3506 } else { 3507 int desiredpages; 3508 3509 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3510 desiredpages = (size == 0) ? 0 : 3511 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 3512 3513 if (bp->b_flags & B_MALLOC) 3514 panic("allocbuf: VMIO buffer can't be malloced"); 3515 /* 3516 * Set B_CACHE initially if buffer is 0 length or will become 3517 * 0-length. 3518 */ 3519 if (size == 0 || bp->b_bufsize == 0) 3520 bp->b_flags |= B_CACHE; 3521 3522 if (newbsize < bp->b_bufsize) { 3523 /* 3524 * DEV_BSIZE aligned new buffer size is less then the 3525 * DEV_BSIZE aligned existing buffer size. Figure out 3526 * if we have to remove any pages. 3527 */ 3528 if (desiredpages < bp->b_npages) { 3529 vm_page_t m; 3530 3531 if ((bp->b_flags & B_UNMAPPED) == 0) { 3532 BUF_CHECK_MAPPED(bp); 3533 pmap_qremove((vm_offset_t)trunc_page( 3534 (vm_offset_t)bp->b_data) + 3535 (desiredpages << PAGE_SHIFT), 3536 (bp->b_npages - desiredpages)); 3537 } else 3538 BUF_CHECK_UNMAPPED(bp); 3539 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 3540 for (i = desiredpages; i < bp->b_npages; i++) { 3541 /* 3542 * the page is not freed here -- it 3543 * is the responsibility of 3544 * vnode_pager_setsize 3545 */ 3546 m = bp->b_pages[i]; 3547 KASSERT(m != bogus_page, 3548 ("allocbuf: bogus page found")); 3549 while (vm_page_sleep_if_busy(m, 3550 "biodep")) 3551 continue; 3552 3553 bp->b_pages[i] = NULL; 3554 vm_page_lock(m); 3555 vm_page_unwire(m, PQ_INACTIVE); 3556 vm_page_unlock(m); 3557 } 3558 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 3559 bp->b_npages = desiredpages; 3560 } 3561 } else if (size > bp->b_bcount) { 3562 /* 3563 * We are growing the buffer, possibly in a 3564 * byte-granular fashion. 3565 */ 3566 vm_object_t obj; 3567 vm_offset_t toff; 3568 vm_offset_t tinc; 3569 3570 /* 3571 * Step 1, bring in the VM pages from the object, 3572 * allocating them if necessary. We must clear 3573 * B_CACHE if these pages are not valid for the 3574 * range covered by the buffer. 3575 */ 3576 3577 obj = bp->b_bufobj->bo_object; 3578 3579 VM_OBJECT_WLOCK(obj); 3580 while (bp->b_npages < desiredpages) { 3581 vm_page_t m; 3582 3583 /* 3584 * We must allocate system pages since blocking 3585 * here could interfere with paging I/O, no 3586 * matter which process we are. 3587 * 3588 * Only exclusive busy can be tested here. 3589 * Blocking on shared busy might lead to 3590 * deadlocks once allocbuf() is called after 3591 * pages are vfs_busy_pages(). 3592 */ 3593 m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) + 3594 bp->b_npages, VM_ALLOC_NOBUSY | 3595 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED | 3596 VM_ALLOC_IGN_SBUSY | 3597 VM_ALLOC_COUNT(desiredpages - bp->b_npages)); 3598 if (m->valid == 0) 3599 bp->b_flags &= ~B_CACHE; 3600 bp->b_pages[bp->b_npages] = m; 3601 ++bp->b_npages; 3602 } 3603 3604 /* 3605 * Step 2. We've loaded the pages into the buffer, 3606 * we have to figure out if we can still have B_CACHE 3607 * set. Note that B_CACHE is set according to the 3608 * byte-granular range ( bcount and size ), new the 3609 * aligned range ( newbsize ). 3610 * 3611 * The VM test is against m->valid, which is DEV_BSIZE 3612 * aligned. Needless to say, the validity of the data 3613 * needs to also be DEV_BSIZE aligned. Note that this 3614 * fails with NFS if the server or some other client 3615 * extends the file's EOF. If our buffer is resized, 3616 * B_CACHE may remain set! XXX 3617 */ 3618 3619 toff = bp->b_bcount; 3620 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 3621 3622 while ((bp->b_flags & B_CACHE) && toff < size) { 3623 vm_pindex_t pi; 3624 3625 if (tinc > (size - toff)) 3626 tinc = size - toff; 3627 3628 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 3629 PAGE_SHIFT; 3630 3631 vfs_buf_test_cache( 3632 bp, 3633 bp->b_offset, 3634 toff, 3635 tinc, 3636 bp->b_pages[pi] 3637 ); 3638 toff += tinc; 3639 tinc = PAGE_SIZE; 3640 } 3641 VM_OBJECT_WUNLOCK(obj); 3642 3643 /* 3644 * Step 3, fixup the KVM pmap. 3645 */ 3646 if ((bp->b_flags & B_UNMAPPED) == 0) 3647 bpmap_qenter(bp); 3648 else 3649 BUF_CHECK_UNMAPPED(bp); 3650 } 3651 } 3652 if (newbsize < bp->b_bufsize) 3653 bufspacewakeup(); 3654 bp->b_bufsize = newbsize; /* actual buffer allocation */ 3655 bp->b_bcount = size; /* requested buffer size */ 3656 return 1; 3657 } 3658 3659 extern int inflight_transient_maps; 3660 3661 void 3662 biodone(struct bio *bp) 3663 { 3664 struct mtx *mtxp; 3665 void (*done)(struct bio *); 3666 vm_offset_t start, end; 3667 3668 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) { 3669 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING; 3670 bp->bio_flags |= BIO_UNMAPPED; 3671 start = trunc_page((vm_offset_t)bp->bio_data); 3672 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length); 3673 bp->bio_data = unmapped_buf; 3674 pmap_qremove(start, OFF_TO_IDX(end - start)); 3675 vmem_free(transient_arena, start, end - start); 3676 atomic_add_int(&inflight_transient_maps, -1); 3677 } 3678 done = bp->bio_done; 3679 if (done == NULL) { 3680 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3681 mtx_lock(mtxp); 3682 bp->bio_flags |= BIO_DONE; 3683 wakeup(bp); 3684 mtx_unlock(mtxp); 3685 } else { 3686 bp->bio_flags |= BIO_DONE; 3687 done(bp); 3688 } 3689 } 3690 3691 /* 3692 * Wait for a BIO to finish. 3693 */ 3694 int 3695 biowait(struct bio *bp, const char *wchan) 3696 { 3697 struct mtx *mtxp; 3698 3699 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3700 mtx_lock(mtxp); 3701 while ((bp->bio_flags & BIO_DONE) == 0) 3702 msleep(bp, mtxp, PRIBIO, wchan, 0); 3703 mtx_unlock(mtxp); 3704 if (bp->bio_error != 0) 3705 return (bp->bio_error); 3706 if (!(bp->bio_flags & BIO_ERROR)) 3707 return (0); 3708 return (EIO); 3709 } 3710 3711 void 3712 biofinish(struct bio *bp, struct devstat *stat, int error) 3713 { 3714 3715 if (error) { 3716 bp->bio_error = error; 3717 bp->bio_flags |= BIO_ERROR; 3718 } 3719 if (stat != NULL) 3720 devstat_end_transaction_bio(stat, bp); 3721 biodone(bp); 3722 } 3723 3724 /* 3725 * bufwait: 3726 * 3727 * Wait for buffer I/O completion, returning error status. The buffer 3728 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3729 * error and cleared. 3730 */ 3731 int 3732 bufwait(struct buf *bp) 3733 { 3734 if (bp->b_iocmd == BIO_READ) 3735 bwait(bp, PRIBIO, "biord"); 3736 else 3737 bwait(bp, PRIBIO, "biowr"); 3738 if (bp->b_flags & B_EINTR) { 3739 bp->b_flags &= ~B_EINTR; 3740 return (EINTR); 3741 } 3742 if (bp->b_ioflags & BIO_ERROR) { 3743 return (bp->b_error ? bp->b_error : EIO); 3744 } else { 3745 return (0); 3746 } 3747 } 3748 3749 /* 3750 * Call back function from struct bio back up to struct buf. 3751 */ 3752 static void 3753 bufdonebio(struct bio *bip) 3754 { 3755 struct buf *bp; 3756 3757 bp = bip->bio_caller2; 3758 bp->b_resid = bip->bio_resid; 3759 bp->b_ioflags = bip->bio_flags; 3760 bp->b_error = bip->bio_error; 3761 if (bp->b_error) 3762 bp->b_ioflags |= BIO_ERROR; 3763 bufdone(bp); 3764 g_destroy_bio(bip); 3765 } 3766 3767 void 3768 dev_strategy(struct cdev *dev, struct buf *bp) 3769 { 3770 struct cdevsw *csw; 3771 int ref; 3772 3773 KASSERT(dev->si_refcount > 0, 3774 ("dev_strategy on un-referenced struct cdev *(%s) %p", 3775 devtoname(dev), dev)); 3776 3777 csw = dev_refthread(dev, &ref); 3778 dev_strategy_csw(dev, csw, bp); 3779 dev_relthread(dev, ref); 3780 } 3781 3782 void 3783 dev_strategy_csw(struct cdev *dev, struct cdevsw *csw, struct buf *bp) 3784 { 3785 struct bio *bip; 3786 3787 KASSERT(bp->b_iocmd == BIO_READ || bp->b_iocmd == BIO_WRITE, 3788 ("b_iocmd botch")); 3789 KASSERT(((dev->si_flags & SI_ETERNAL) != 0 && csw != NULL) || 3790 dev->si_threadcount > 0, 3791 ("dev_strategy_csw threadcount cdev *(%s) %p", devtoname(dev), 3792 dev)); 3793 if (csw == NULL) { 3794 bp->b_error = ENXIO; 3795 bp->b_ioflags = BIO_ERROR; 3796 bufdone(bp); 3797 return; 3798 } 3799 for (;;) { 3800 bip = g_new_bio(); 3801 if (bip != NULL) 3802 break; 3803 /* Try again later */ 3804 tsleep(&bp, PRIBIO, "dev_strat", hz/10); 3805 } 3806 bip->bio_cmd = bp->b_iocmd; 3807 bip->bio_offset = bp->b_iooffset; 3808 bip->bio_length = bp->b_bcount; 3809 bip->bio_bcount = bp->b_bcount; /* XXX: remove */ 3810 bdata2bio(bp, bip); 3811 bip->bio_done = bufdonebio; 3812 bip->bio_caller2 = bp; 3813 bip->bio_dev = dev; 3814 (*csw->d_strategy)(bip); 3815 } 3816 3817 /* 3818 * bufdone: 3819 * 3820 * Finish I/O on a buffer, optionally calling a completion function. 3821 * This is usually called from an interrupt so process blocking is 3822 * not allowed. 3823 * 3824 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3825 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3826 * assuming B_INVAL is clear. 3827 * 3828 * For the VMIO case, we set B_CACHE if the op was a read and no 3829 * read error occured, or if the op was a write. B_CACHE is never 3830 * set if the buffer is invalid or otherwise uncacheable. 3831 * 3832 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3833 * initiator to leave B_INVAL set to brelse the buffer out of existance 3834 * in the biodone routine. 3835 */ 3836 void 3837 bufdone(struct buf *bp) 3838 { 3839 struct bufobj *dropobj; 3840 void (*biodone)(struct buf *); 3841 3842 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 3843 dropobj = NULL; 3844 3845 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 3846 BUF_ASSERT_HELD(bp); 3847 3848 runningbufwakeup(bp); 3849 if (bp->b_iocmd == BIO_WRITE) 3850 dropobj = bp->b_bufobj; 3851 /* call optional completion function if requested */ 3852 if (bp->b_iodone != NULL) { 3853 biodone = bp->b_iodone; 3854 bp->b_iodone = NULL; 3855 (*biodone) (bp); 3856 if (dropobj) 3857 bufobj_wdrop(dropobj); 3858 return; 3859 } 3860 3861 bufdone_finish(bp); 3862 3863 if (dropobj) 3864 bufobj_wdrop(dropobj); 3865 } 3866 3867 void 3868 bufdone_finish(struct buf *bp) 3869 { 3870 BUF_ASSERT_HELD(bp); 3871 3872 if (!LIST_EMPTY(&bp->b_dep)) 3873 buf_complete(bp); 3874 3875 if (bp->b_flags & B_VMIO) { 3876 vm_ooffset_t foff; 3877 vm_page_t m; 3878 vm_object_t obj; 3879 struct vnode *vp; 3880 int bogus, i, iosize; 3881 3882 obj = bp->b_bufobj->bo_object; 3883 KASSERT(obj->paging_in_progress >= bp->b_npages, 3884 ("biodone_finish: paging in progress(%d) < b_npages(%d)", 3885 obj->paging_in_progress, bp->b_npages)); 3886 3887 vp = bp->b_vp; 3888 KASSERT(vp->v_holdcnt > 0, 3889 ("biodone_finish: vnode %p has zero hold count", vp)); 3890 KASSERT(vp->v_object != NULL, 3891 ("biodone_finish: vnode %p has no vm_object", vp)); 3892 3893 foff = bp->b_offset; 3894 KASSERT(bp->b_offset != NOOFFSET, 3895 ("biodone_finish: bp %p has no buffer offset", bp)); 3896 3897 /* 3898 * Set B_CACHE if the op was a normal read and no error 3899 * occured. B_CACHE is set for writes in the b*write() 3900 * routines. 3901 */ 3902 iosize = bp->b_bcount - bp->b_resid; 3903 if (bp->b_iocmd == BIO_READ && 3904 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 3905 !(bp->b_ioflags & BIO_ERROR)) { 3906 bp->b_flags |= B_CACHE; 3907 } 3908 bogus = 0; 3909 VM_OBJECT_WLOCK(obj); 3910 for (i = 0; i < bp->b_npages; i++) { 3911 int bogusflag = 0; 3912 int resid; 3913 3914 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 3915 if (resid > iosize) 3916 resid = iosize; 3917 3918 /* 3919 * cleanup bogus pages, restoring the originals 3920 */ 3921 m = bp->b_pages[i]; 3922 if (m == bogus_page) { 3923 bogus = bogusflag = 1; 3924 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3925 if (m == NULL) 3926 panic("biodone: page disappeared!"); 3927 bp->b_pages[i] = m; 3928 } 3929 KASSERT(OFF_TO_IDX(foff) == m->pindex, 3930 ("biodone_finish: foff(%jd)/pindex(%ju) mismatch", 3931 (intmax_t)foff, (uintmax_t)m->pindex)); 3932 3933 /* 3934 * In the write case, the valid and clean bits are 3935 * already changed correctly ( see bdwrite() ), so we 3936 * only need to do this here in the read case. 3937 */ 3938 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 3939 KASSERT((m->dirty & vm_page_bits(foff & 3940 PAGE_MASK, resid)) == 0, ("bufdone_finish:" 3941 " page %p has unexpected dirty bits", m)); 3942 vfs_page_set_valid(bp, foff, m); 3943 } 3944 3945 vm_page_sunbusy(m); 3946 vm_object_pip_subtract(obj, 1); 3947 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3948 iosize -= resid; 3949 } 3950 vm_object_pip_wakeupn(obj, 0); 3951 VM_OBJECT_WUNLOCK(obj); 3952 if (bogus && (bp->b_flags & B_UNMAPPED) == 0) { 3953 BUF_CHECK_MAPPED(bp); 3954 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3955 bp->b_pages, bp->b_npages); 3956 } 3957 } 3958 3959 /* 3960 * For asynchronous completions, release the buffer now. The brelse 3961 * will do a wakeup there if necessary - so no need to do a wakeup 3962 * here in the async case. The sync case always needs to do a wakeup. 3963 */ 3964 3965 if (bp->b_flags & B_ASYNC) { 3966 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 3967 brelse(bp); 3968 else 3969 bqrelse(bp); 3970 } else 3971 bdone(bp); 3972 } 3973 3974 /* 3975 * This routine is called in lieu of iodone in the case of 3976 * incomplete I/O. This keeps the busy status for pages 3977 * consistant. 3978 */ 3979 void 3980 vfs_unbusy_pages(struct buf *bp) 3981 { 3982 int i; 3983 vm_object_t obj; 3984 vm_page_t m; 3985 3986 runningbufwakeup(bp); 3987 if (!(bp->b_flags & B_VMIO)) 3988 return; 3989 3990 obj = bp->b_bufobj->bo_object; 3991 VM_OBJECT_WLOCK(obj); 3992 for (i = 0; i < bp->b_npages; i++) { 3993 m = bp->b_pages[i]; 3994 if (m == bogus_page) { 3995 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 3996 if (!m) 3997 panic("vfs_unbusy_pages: page missing\n"); 3998 bp->b_pages[i] = m; 3999 if ((bp->b_flags & B_UNMAPPED) == 0) { 4000 BUF_CHECK_MAPPED(bp); 4001 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4002 bp->b_pages, bp->b_npages); 4003 } else 4004 BUF_CHECK_UNMAPPED(bp); 4005 } 4006 vm_object_pip_subtract(obj, 1); 4007 vm_page_sunbusy(m); 4008 } 4009 vm_object_pip_wakeupn(obj, 0); 4010 VM_OBJECT_WUNLOCK(obj); 4011 } 4012 4013 /* 4014 * vfs_page_set_valid: 4015 * 4016 * Set the valid bits in a page based on the supplied offset. The 4017 * range is restricted to the buffer's size. 4018 * 4019 * This routine is typically called after a read completes. 4020 */ 4021 static void 4022 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4023 { 4024 vm_ooffset_t eoff; 4025 4026 /* 4027 * Compute the end offset, eoff, such that [off, eoff) does not span a 4028 * page boundary and eoff is not greater than the end of the buffer. 4029 * The end of the buffer, in this case, is our file EOF, not the 4030 * allocation size of the buffer. 4031 */ 4032 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 4033 if (eoff > bp->b_offset + bp->b_bcount) 4034 eoff = bp->b_offset + bp->b_bcount; 4035 4036 /* 4037 * Set valid range. This is typically the entire buffer and thus the 4038 * entire page. 4039 */ 4040 if (eoff > off) 4041 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off); 4042 } 4043 4044 /* 4045 * vfs_page_set_validclean: 4046 * 4047 * Set the valid bits and clear the dirty bits in a page based on the 4048 * supplied offset. The range is restricted to the buffer's size. 4049 */ 4050 static void 4051 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4052 { 4053 vm_ooffset_t soff, eoff; 4054 4055 /* 4056 * Start and end offsets in buffer. eoff - soff may not cross a 4057 * page boundry or cross the end of the buffer. The end of the 4058 * buffer, in this case, is our file EOF, not the allocation size 4059 * of the buffer. 4060 */ 4061 soff = off; 4062 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4063 if (eoff > bp->b_offset + bp->b_bcount) 4064 eoff = bp->b_offset + bp->b_bcount; 4065 4066 /* 4067 * Set valid range. This is typically the entire buffer and thus the 4068 * entire page. 4069 */ 4070 if (eoff > soff) { 4071 vm_page_set_validclean( 4072 m, 4073 (vm_offset_t) (soff & PAGE_MASK), 4074 (vm_offset_t) (eoff - soff) 4075 ); 4076 } 4077 } 4078 4079 /* 4080 * Ensure that all buffer pages are not exclusive busied. If any page is 4081 * exclusive busy, drain it. 4082 */ 4083 void 4084 vfs_drain_busy_pages(struct buf *bp) 4085 { 4086 vm_page_t m; 4087 int i, last_busied; 4088 4089 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object); 4090 last_busied = 0; 4091 for (i = 0; i < bp->b_npages; i++) { 4092 m = bp->b_pages[i]; 4093 if (vm_page_xbusied(m)) { 4094 for (; last_busied < i; last_busied++) 4095 vm_page_sbusy(bp->b_pages[last_busied]); 4096 while (vm_page_xbusied(m)) { 4097 vm_page_lock(m); 4098 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4099 vm_page_busy_sleep(m, "vbpage"); 4100 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4101 } 4102 } 4103 } 4104 for (i = 0; i < last_busied; i++) 4105 vm_page_sunbusy(bp->b_pages[i]); 4106 } 4107 4108 /* 4109 * This routine is called before a device strategy routine. 4110 * It is used to tell the VM system that paging I/O is in 4111 * progress, and treat the pages associated with the buffer 4112 * almost as being exclusive busy. Also the object paging_in_progress 4113 * flag is handled to make sure that the object doesn't become 4114 * inconsistant. 4115 * 4116 * Since I/O has not been initiated yet, certain buffer flags 4117 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 4118 * and should be ignored. 4119 */ 4120 void 4121 vfs_busy_pages(struct buf *bp, int clear_modify) 4122 { 4123 int i, bogus; 4124 vm_object_t obj; 4125 vm_ooffset_t foff; 4126 vm_page_t m; 4127 4128 if (!(bp->b_flags & B_VMIO)) 4129 return; 4130 4131 obj = bp->b_bufobj->bo_object; 4132 foff = bp->b_offset; 4133 KASSERT(bp->b_offset != NOOFFSET, 4134 ("vfs_busy_pages: no buffer offset")); 4135 VM_OBJECT_WLOCK(obj); 4136 vfs_drain_busy_pages(bp); 4137 if (bp->b_bufsize != 0) 4138 vfs_setdirty_locked_object(bp); 4139 bogus = 0; 4140 for (i = 0; i < bp->b_npages; i++) { 4141 m = bp->b_pages[i]; 4142 4143 if ((bp->b_flags & B_CLUSTER) == 0) { 4144 vm_object_pip_add(obj, 1); 4145 vm_page_sbusy(m); 4146 } 4147 /* 4148 * When readying a buffer for a read ( i.e 4149 * clear_modify == 0 ), it is important to do 4150 * bogus_page replacement for valid pages in 4151 * partially instantiated buffers. Partially 4152 * instantiated buffers can, in turn, occur when 4153 * reconstituting a buffer from its VM backing store 4154 * base. We only have to do this if B_CACHE is 4155 * clear ( which causes the I/O to occur in the 4156 * first place ). The replacement prevents the read 4157 * I/O from overwriting potentially dirty VM-backed 4158 * pages. XXX bogus page replacement is, uh, bogus. 4159 * It may not work properly with small-block devices. 4160 * We need to find a better way. 4161 */ 4162 if (clear_modify) { 4163 pmap_remove_write(m); 4164 vfs_page_set_validclean(bp, foff, m); 4165 } else if (m->valid == VM_PAGE_BITS_ALL && 4166 (bp->b_flags & B_CACHE) == 0) { 4167 bp->b_pages[i] = bogus_page; 4168 bogus++; 4169 } 4170 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4171 } 4172 VM_OBJECT_WUNLOCK(obj); 4173 if (bogus && (bp->b_flags & B_UNMAPPED) == 0) { 4174 BUF_CHECK_MAPPED(bp); 4175 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4176 bp->b_pages, bp->b_npages); 4177 } 4178 } 4179 4180 /* 4181 * vfs_bio_set_valid: 4182 * 4183 * Set the range within the buffer to valid. The range is 4184 * relative to the beginning of the buffer, b_offset. Note that 4185 * b_offset itself may be offset from the beginning of the first 4186 * page. 4187 */ 4188 void 4189 vfs_bio_set_valid(struct buf *bp, int base, int size) 4190 { 4191 int i, n; 4192 vm_page_t m; 4193 4194 if (!(bp->b_flags & B_VMIO)) 4195 return; 4196 4197 /* 4198 * Fixup base to be relative to beginning of first page. 4199 * Set initial n to be the maximum number of bytes in the 4200 * first page that can be validated. 4201 */ 4202 base += (bp->b_offset & PAGE_MASK); 4203 n = PAGE_SIZE - (base & PAGE_MASK); 4204 4205 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4206 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4207 m = bp->b_pages[i]; 4208 if (n > size) 4209 n = size; 4210 vm_page_set_valid_range(m, base & PAGE_MASK, n); 4211 base += n; 4212 size -= n; 4213 n = PAGE_SIZE; 4214 } 4215 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4216 } 4217 4218 /* 4219 * vfs_bio_clrbuf: 4220 * 4221 * If the specified buffer is a non-VMIO buffer, clear the entire 4222 * buffer. If the specified buffer is a VMIO buffer, clear and 4223 * validate only the previously invalid portions of the buffer. 4224 * This routine essentially fakes an I/O, so we need to clear 4225 * BIO_ERROR and B_INVAL. 4226 * 4227 * Note that while we only theoretically need to clear through b_bcount, 4228 * we go ahead and clear through b_bufsize. 4229 */ 4230 void 4231 vfs_bio_clrbuf(struct buf *bp) 4232 { 4233 int i, j, mask, sa, ea, slide; 4234 4235 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 4236 clrbuf(bp); 4237 return; 4238 } 4239 bp->b_flags &= ~B_INVAL; 4240 bp->b_ioflags &= ~BIO_ERROR; 4241 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4242 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 4243 (bp->b_offset & PAGE_MASK) == 0) { 4244 if (bp->b_pages[0] == bogus_page) 4245 goto unlock; 4246 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 4247 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object); 4248 if ((bp->b_pages[0]->valid & mask) == mask) 4249 goto unlock; 4250 if ((bp->b_pages[0]->valid & mask) == 0) { 4251 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize); 4252 bp->b_pages[0]->valid |= mask; 4253 goto unlock; 4254 } 4255 } 4256 sa = bp->b_offset & PAGE_MASK; 4257 slide = 0; 4258 for (i = 0; i < bp->b_npages; i++, sa = 0) { 4259 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize); 4260 ea = slide & PAGE_MASK; 4261 if (ea == 0) 4262 ea = PAGE_SIZE; 4263 if (bp->b_pages[i] == bogus_page) 4264 continue; 4265 j = sa / DEV_BSIZE; 4266 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 4267 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object); 4268 if ((bp->b_pages[i]->valid & mask) == mask) 4269 continue; 4270 if ((bp->b_pages[i]->valid & mask) == 0) 4271 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa); 4272 else { 4273 for (; sa < ea; sa += DEV_BSIZE, j++) { 4274 if ((bp->b_pages[i]->valid & (1 << j)) == 0) { 4275 pmap_zero_page_area(bp->b_pages[i], 4276 sa, DEV_BSIZE); 4277 } 4278 } 4279 } 4280 bp->b_pages[i]->valid |= mask; 4281 } 4282 unlock: 4283 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4284 bp->b_resid = 0; 4285 } 4286 4287 void 4288 vfs_bio_bzero_buf(struct buf *bp, int base, int size) 4289 { 4290 vm_page_t m; 4291 int i, n; 4292 4293 if ((bp->b_flags & B_UNMAPPED) == 0) { 4294 BUF_CHECK_MAPPED(bp); 4295 bzero(bp->b_data + base, size); 4296 } else { 4297 BUF_CHECK_UNMAPPED(bp); 4298 n = PAGE_SIZE - (base & PAGE_MASK); 4299 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4300 m = bp->b_pages[i]; 4301 if (n > size) 4302 n = size; 4303 pmap_zero_page_area(m, base & PAGE_MASK, n); 4304 base += n; 4305 size -= n; 4306 n = PAGE_SIZE; 4307 } 4308 } 4309 } 4310 4311 /* 4312 * vm_hold_load_pages and vm_hold_free_pages get pages into 4313 * a buffers address space. The pages are anonymous and are 4314 * not associated with a file object. 4315 */ 4316 static void 4317 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4318 { 4319 vm_offset_t pg; 4320 vm_page_t p; 4321 int index; 4322 4323 BUF_CHECK_MAPPED(bp); 4324 4325 to = round_page(to); 4326 from = round_page(from); 4327 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4328 4329 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 4330 tryagain: 4331 /* 4332 * note: must allocate system pages since blocking here 4333 * could interfere with paging I/O, no matter which 4334 * process we are. 4335 */ 4336 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ | 4337 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT)); 4338 if (p == NULL) { 4339 VM_WAIT; 4340 goto tryagain; 4341 } 4342 pmap_qenter(pg, &p, 1); 4343 bp->b_pages[index] = p; 4344 } 4345 bp->b_npages = index; 4346 } 4347 4348 /* Return pages associated with this buf to the vm system */ 4349 static void 4350 vm_hold_free_pages(struct buf *bp, int newbsize) 4351 { 4352 vm_offset_t from; 4353 vm_page_t p; 4354 int index, newnpages; 4355 4356 BUF_CHECK_MAPPED(bp); 4357 4358 from = round_page((vm_offset_t)bp->b_data + newbsize); 4359 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4360 if (bp->b_npages > newnpages) 4361 pmap_qremove(from, bp->b_npages - newnpages); 4362 for (index = newnpages; index < bp->b_npages; index++) { 4363 p = bp->b_pages[index]; 4364 bp->b_pages[index] = NULL; 4365 if (vm_page_sbusied(p)) 4366 printf("vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 4367 (intmax_t)bp->b_blkno, (intmax_t)bp->b_lblkno); 4368 p->wire_count--; 4369 vm_page_free(p); 4370 atomic_subtract_int(&vm_cnt.v_wire_count, 1); 4371 } 4372 bp->b_npages = newnpages; 4373 } 4374 4375 /* 4376 * Map an IO request into kernel virtual address space. 4377 * 4378 * All requests are (re)mapped into kernel VA space. 4379 * Notice that we use b_bufsize for the size of the buffer 4380 * to be mapped. b_bcount might be modified by the driver. 4381 * 4382 * Note that even if the caller determines that the address space should 4383 * be valid, a race or a smaller-file mapped into a larger space may 4384 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 4385 * check the return value. 4386 */ 4387 int 4388 vmapbuf(struct buf *bp, int mapbuf) 4389 { 4390 caddr_t kva; 4391 vm_prot_t prot; 4392 int pidx; 4393 4394 if (bp->b_bufsize < 0) 4395 return (-1); 4396 prot = VM_PROT_READ; 4397 if (bp->b_iocmd == BIO_READ) 4398 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 4399 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 4400 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages, 4401 btoc(MAXPHYS))) < 0) 4402 return (-1); 4403 bp->b_npages = pidx; 4404 if (mapbuf || !unmapped_buf_allowed) { 4405 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx); 4406 kva = bp->b_saveaddr; 4407 bp->b_saveaddr = bp->b_data; 4408 bp->b_data = kva + (((vm_offset_t)bp->b_data) & PAGE_MASK); 4409 bp->b_flags &= ~B_UNMAPPED; 4410 } else { 4411 bp->b_flags |= B_UNMAPPED; 4412 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK; 4413 bp->b_saveaddr = bp->b_data; 4414 bp->b_data = unmapped_buf; 4415 } 4416 return(0); 4417 } 4418 4419 /* 4420 * Free the io map PTEs associated with this IO operation. 4421 * We also invalidate the TLB entries and restore the original b_addr. 4422 */ 4423 void 4424 vunmapbuf(struct buf *bp) 4425 { 4426 int npages; 4427 4428 npages = bp->b_npages; 4429 if (bp->b_flags & B_UNMAPPED) 4430 bp->b_flags &= ~B_UNMAPPED; 4431 else 4432 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 4433 vm_page_unhold_pages(bp->b_pages, npages); 4434 4435 bp->b_data = bp->b_saveaddr; 4436 } 4437 4438 void 4439 bdone(struct buf *bp) 4440 { 4441 struct mtx *mtxp; 4442 4443 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4444 mtx_lock(mtxp); 4445 bp->b_flags |= B_DONE; 4446 wakeup(bp); 4447 mtx_unlock(mtxp); 4448 } 4449 4450 void 4451 bwait(struct buf *bp, u_char pri, const char *wchan) 4452 { 4453 struct mtx *mtxp; 4454 4455 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4456 mtx_lock(mtxp); 4457 while ((bp->b_flags & B_DONE) == 0) 4458 msleep(bp, mtxp, pri, wchan, 0); 4459 mtx_unlock(mtxp); 4460 } 4461 4462 int 4463 bufsync(struct bufobj *bo, int waitfor) 4464 { 4465 4466 return (VOP_FSYNC(bo->__bo_vnode, waitfor, curthread)); 4467 } 4468 4469 void 4470 bufstrategy(struct bufobj *bo, struct buf *bp) 4471 { 4472 int i = 0; 4473 struct vnode *vp; 4474 4475 vp = bp->b_vp; 4476 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 4477 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 4478 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 4479 i = VOP_STRATEGY(vp, bp); 4480 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 4481 } 4482 4483 void 4484 bufobj_wrefl(struct bufobj *bo) 4485 { 4486 4487 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4488 ASSERT_BO_WLOCKED(bo); 4489 bo->bo_numoutput++; 4490 } 4491 4492 void 4493 bufobj_wref(struct bufobj *bo) 4494 { 4495 4496 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4497 BO_LOCK(bo); 4498 bo->bo_numoutput++; 4499 BO_UNLOCK(bo); 4500 } 4501 4502 void 4503 bufobj_wdrop(struct bufobj *bo) 4504 { 4505 4506 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 4507 BO_LOCK(bo); 4508 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 4509 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 4510 bo->bo_flag &= ~BO_WWAIT; 4511 wakeup(&bo->bo_numoutput); 4512 } 4513 BO_UNLOCK(bo); 4514 } 4515 4516 int 4517 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 4518 { 4519 int error; 4520 4521 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 4522 ASSERT_BO_WLOCKED(bo); 4523 error = 0; 4524 while (bo->bo_numoutput) { 4525 bo->bo_flag |= BO_WWAIT; 4526 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo), 4527 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 4528 if (error) 4529 break; 4530 } 4531 return (error); 4532 } 4533 4534 void 4535 bpin(struct buf *bp) 4536 { 4537 struct mtx *mtxp; 4538 4539 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4540 mtx_lock(mtxp); 4541 bp->b_pin_count++; 4542 mtx_unlock(mtxp); 4543 } 4544 4545 void 4546 bunpin(struct buf *bp) 4547 { 4548 struct mtx *mtxp; 4549 4550 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4551 mtx_lock(mtxp); 4552 if (--bp->b_pin_count == 0) 4553 wakeup(bp); 4554 mtx_unlock(mtxp); 4555 } 4556 4557 void 4558 bunpin_wait(struct buf *bp) 4559 { 4560 struct mtx *mtxp; 4561 4562 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4563 mtx_lock(mtxp); 4564 while (bp->b_pin_count > 0) 4565 msleep(bp, mtxp, PRIBIO, "bwunpin", 0); 4566 mtx_unlock(mtxp); 4567 } 4568 4569 /* 4570 * Set bio_data or bio_ma for struct bio from the struct buf. 4571 */ 4572 void 4573 bdata2bio(struct buf *bp, struct bio *bip) 4574 { 4575 4576 if ((bp->b_flags & B_UNMAPPED) != 0) { 4577 KASSERT(unmapped_buf_allowed, ("unmapped")); 4578 bip->bio_ma = bp->b_pages; 4579 bip->bio_ma_n = bp->b_npages; 4580 bip->bio_data = unmapped_buf; 4581 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 4582 bip->bio_flags |= BIO_UNMAPPED; 4583 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) / 4584 PAGE_SIZE == bp->b_npages, 4585 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset, 4586 (long long)bip->bio_length, bip->bio_ma_n)); 4587 } else { 4588 bip->bio_data = bp->b_data; 4589 bip->bio_ma = NULL; 4590 } 4591 } 4592 4593 #include "opt_ddb.h" 4594 #ifdef DDB 4595 #include <ddb/ddb.h> 4596 4597 /* DDB command to show buffer data */ 4598 DB_SHOW_COMMAND(buffer, db_show_buffer) 4599 { 4600 /* get args */ 4601 struct buf *bp = (struct buf *)addr; 4602 4603 if (!have_addr) { 4604 db_printf("usage: show buffer <addr>\n"); 4605 return; 4606 } 4607 4608 db_printf("buf at %p\n", bp); 4609 db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n", 4610 (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags, 4611 PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS); 4612 db_printf( 4613 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 4614 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, " 4615 "b_dep = %p\n", 4616 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 4617 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 4618 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first); 4619 if (bp->b_npages) { 4620 int i; 4621 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 4622 for (i = 0; i < bp->b_npages; i++) { 4623 vm_page_t m; 4624 m = bp->b_pages[i]; 4625 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 4626 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 4627 if ((i + 1) < bp->b_npages) 4628 db_printf(","); 4629 } 4630 db_printf("\n"); 4631 } 4632 db_printf(" "); 4633 BUF_LOCKPRINTINFO(bp); 4634 } 4635 4636 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 4637 { 4638 struct buf *bp; 4639 int i; 4640 4641 for (i = 0; i < nbuf; i++) { 4642 bp = &buf[i]; 4643 if (BUF_ISLOCKED(bp)) { 4644 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4645 db_printf("\n"); 4646 } 4647 } 4648 } 4649 4650 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 4651 { 4652 struct vnode *vp; 4653 struct buf *bp; 4654 4655 if (!have_addr) { 4656 db_printf("usage: show vnodebufs <addr>\n"); 4657 return; 4658 } 4659 vp = (struct vnode *)addr; 4660 db_printf("Clean buffers:\n"); 4661 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 4662 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4663 db_printf("\n"); 4664 } 4665 db_printf("Dirty buffers:\n"); 4666 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 4667 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4668 db_printf("\n"); 4669 } 4670 } 4671 4672 DB_COMMAND(countfreebufs, db_coundfreebufs) 4673 { 4674 struct buf *bp; 4675 int i, used = 0, nfree = 0; 4676 4677 if (have_addr) { 4678 db_printf("usage: countfreebufs\n"); 4679 return; 4680 } 4681 4682 for (i = 0; i < nbuf; i++) { 4683 bp = &buf[i]; 4684 if ((bp->b_flags & B_INFREECNT) != 0) 4685 nfree++; 4686 else 4687 used++; 4688 } 4689 4690 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 4691 nfree + used); 4692 db_printf("numfreebuffers is %d\n", numfreebuffers); 4693 } 4694 #endif /* DDB */ 4695