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_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 1601 bp->b_error == EIO && !(bp->b_flags & B_INVAL)) { 1602 /* 1603 * Failed write, redirty. Must clear BIO_ERROR to prevent 1604 * pages from being scrapped. If the error is anything 1605 * other than an I/O error (EIO), assume that retrying 1606 * is futile. 1607 */ 1608 bp->b_ioflags &= ~BIO_ERROR; 1609 bdirty(bp); 1610 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 1611 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 1612 /* 1613 * Either a failed I/O or we were asked to free or not 1614 * cache the buffer. 1615 */ 1616 bp->b_flags |= B_INVAL; 1617 if (!LIST_EMPTY(&bp->b_dep)) 1618 buf_deallocate(bp); 1619 if (bp->b_flags & B_DELWRI) 1620 bdirtysub(); 1621 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1622 if ((bp->b_flags & B_VMIO) == 0) { 1623 if (bp->b_bufsize) 1624 allocbuf(bp, 0); 1625 if (bp->b_vp) 1626 brelvp(bp); 1627 } 1628 } 1629 1630 /* 1631 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1632 * is called with B_DELWRI set, the underlying pages may wind up 1633 * getting freed causing a previous write (bdwrite()) to get 'lost' 1634 * because pages associated with a B_DELWRI bp are marked clean. 1635 * 1636 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1637 * if B_DELWRI is set. 1638 * 1639 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1640 * on pages to return pages to the VM page queues. 1641 */ 1642 if (bp->b_flags & B_DELWRI) 1643 bp->b_flags &= ~B_RELBUF; 1644 else if (buf_vm_page_count_severe()) { 1645 /* 1646 * BKGRDINPROG can only be set with the buf and bufobj 1647 * locks both held. We tolerate a race to clear it here. 1648 */ 1649 if (!(bp->b_vflags & BV_BKGRDINPROG)) 1650 bp->b_flags |= B_RELBUF; 1651 } 1652 1653 /* 1654 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1655 * constituted, not even NFS buffers now. Two flags effect this. If 1656 * B_INVAL, the struct buf is invalidated but the VM object is kept 1657 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1658 * 1659 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 1660 * invalidated. BIO_ERROR cannot be set for a failed write unless the 1661 * buffer is also B_INVAL because it hits the re-dirtying code above. 1662 * 1663 * Normally we can do this whether a buffer is B_DELWRI or not. If 1664 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1665 * the commit state and we cannot afford to lose the buffer. If the 1666 * buffer has a background write in progress, we need to keep it 1667 * around to prevent it from being reconstituted and starting a second 1668 * background write. 1669 */ 1670 if ((bp->b_flags & B_VMIO) 1671 && !(bp->b_vp->v_mount != NULL && 1672 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 1673 !vn_isdisk(bp->b_vp, NULL) && 1674 (bp->b_flags & B_DELWRI)) 1675 ) { 1676 1677 int i, j, resid; 1678 vm_page_t m; 1679 off_t foff; 1680 vm_pindex_t poff; 1681 vm_object_t obj; 1682 1683 obj = bp->b_bufobj->bo_object; 1684 1685 /* 1686 * Get the base offset and length of the buffer. Note that 1687 * in the VMIO case if the buffer block size is not 1688 * page-aligned then b_data pointer may not be page-aligned. 1689 * But our b_pages[] array *IS* page aligned. 1690 * 1691 * block sizes less then DEV_BSIZE (usually 512) are not 1692 * supported due to the page granularity bits (m->valid, 1693 * m->dirty, etc...). 1694 * 1695 * See man buf(9) for more information 1696 */ 1697 resid = bp->b_bufsize; 1698 foff = bp->b_offset; 1699 for (i = 0; i < bp->b_npages; i++) { 1700 int had_bogus = 0; 1701 1702 m = bp->b_pages[i]; 1703 1704 /* 1705 * If we hit a bogus page, fixup *all* the bogus pages 1706 * now. 1707 */ 1708 if (m == bogus_page) { 1709 poff = OFF_TO_IDX(bp->b_offset); 1710 had_bogus = 1; 1711 1712 VM_OBJECT_RLOCK(obj); 1713 for (j = i; j < bp->b_npages; j++) { 1714 vm_page_t mtmp; 1715 mtmp = bp->b_pages[j]; 1716 if (mtmp == bogus_page) { 1717 mtmp = vm_page_lookup(obj, poff + j); 1718 if (!mtmp) { 1719 panic("brelse: page missing\n"); 1720 } 1721 bp->b_pages[j] = mtmp; 1722 } 1723 } 1724 VM_OBJECT_RUNLOCK(obj); 1725 1726 if ((bp->b_flags & (B_INVAL | B_UNMAPPED)) == 0) { 1727 BUF_CHECK_MAPPED(bp); 1728 pmap_qenter( 1729 trunc_page((vm_offset_t)bp->b_data), 1730 bp->b_pages, bp->b_npages); 1731 } 1732 m = bp->b_pages[i]; 1733 } 1734 if ((bp->b_flags & B_NOCACHE) || 1735 (bp->b_ioflags & BIO_ERROR && 1736 bp->b_iocmd == BIO_READ)) { 1737 int poffset = foff & PAGE_MASK; 1738 int presid = resid > (PAGE_SIZE - poffset) ? 1739 (PAGE_SIZE - poffset) : resid; 1740 1741 KASSERT(presid >= 0, ("brelse: extra page")); 1742 VM_OBJECT_WLOCK(obj); 1743 while (vm_page_xbusied(m)) { 1744 vm_page_lock(m); 1745 VM_OBJECT_WUNLOCK(obj); 1746 vm_page_busy_sleep(m, "mbncsh"); 1747 VM_OBJECT_WLOCK(obj); 1748 } 1749 if (pmap_page_wired_mappings(m) == 0) 1750 vm_page_set_invalid(m, poffset, presid); 1751 VM_OBJECT_WUNLOCK(obj); 1752 if (had_bogus) 1753 printf("avoided corruption bug in bogus_page/brelse code\n"); 1754 } 1755 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1756 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1757 } 1758 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1759 vfs_vmio_release(bp); 1760 1761 } else if (bp->b_flags & B_VMIO) { 1762 1763 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1764 vfs_vmio_release(bp); 1765 } 1766 1767 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) { 1768 if (bp->b_bufsize != 0) 1769 allocbuf(bp, 0); 1770 if (bp->b_vp != NULL) 1771 brelvp(bp); 1772 } 1773 1774 /* 1775 * If the buffer has junk contents signal it and eventually 1776 * clean up B_DELWRI and diassociate the vnode so that gbincore() 1777 * doesn't find it. 1778 */ 1779 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 1780 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 1781 bp->b_flags |= B_INVAL; 1782 if (bp->b_flags & B_INVAL) { 1783 if (bp->b_flags & B_DELWRI) 1784 bundirty(bp); 1785 if (bp->b_vp) 1786 brelvp(bp); 1787 } 1788 1789 /* buffers with no memory */ 1790 if (bp->b_bufsize == 0) { 1791 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1792 if (bp->b_vflags & BV_BKGRDINPROG) 1793 panic("losing buffer 1"); 1794 if (bp->b_kvasize) 1795 qindex = QUEUE_EMPTYKVA; 1796 else 1797 qindex = QUEUE_EMPTY; 1798 bp->b_flags |= B_AGE; 1799 /* buffers with junk contents */ 1800 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 1801 (bp->b_ioflags & BIO_ERROR)) { 1802 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1803 if (bp->b_vflags & BV_BKGRDINPROG) 1804 panic("losing buffer 2"); 1805 qindex = QUEUE_CLEAN; 1806 bp->b_flags |= B_AGE; 1807 /* remaining buffers */ 1808 } else if (bp->b_flags & B_DELWRI) 1809 qindex = QUEUE_DIRTY; 1810 else 1811 qindex = QUEUE_CLEAN; 1812 1813 binsfree(bp, qindex); 1814 1815 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 1816 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1817 panic("brelse: not dirty"); 1818 /* unlock */ 1819 BUF_UNLOCK(bp); 1820 } 1821 1822 /* 1823 * Release a buffer back to the appropriate queue but do not try to free 1824 * it. The buffer is expected to be used again soon. 1825 * 1826 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1827 * biodone() to requeue an async I/O on completion. It is also used when 1828 * known good buffers need to be requeued but we think we may need the data 1829 * again soon. 1830 * 1831 * XXX we should be able to leave the B_RELBUF hint set on completion. 1832 */ 1833 void 1834 bqrelse(struct buf *bp) 1835 { 1836 int qindex; 1837 1838 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1839 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1840 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1841 1842 if (BUF_LOCKRECURSED(bp)) { 1843 /* do not release to free list */ 1844 BUF_UNLOCK(bp); 1845 return; 1846 } 1847 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1848 1849 if (bp->b_flags & B_MANAGED) { 1850 if (bp->b_flags & B_REMFREE) 1851 bremfreef(bp); 1852 goto out; 1853 } 1854 1855 /* buffers with stale but valid contents */ 1856 if (bp->b_flags & B_DELWRI) { 1857 qindex = QUEUE_DIRTY; 1858 } else { 1859 if ((bp->b_flags & B_DELWRI) == 0 && 1860 (bp->b_xflags & BX_VNDIRTY)) 1861 panic("bqrelse: not dirty"); 1862 /* 1863 * BKGRDINPROG can only be set with the buf and bufobj 1864 * locks both held. We tolerate a race to clear it here. 1865 */ 1866 if (buf_vm_page_count_severe() && 1867 (bp->b_vflags & BV_BKGRDINPROG) == 0) { 1868 /* 1869 * We are too low on memory, we have to try to free 1870 * the buffer (most importantly: the wired pages 1871 * making up its backing store) *now*. 1872 */ 1873 brelse(bp); 1874 return; 1875 } 1876 qindex = QUEUE_CLEAN; 1877 } 1878 binsfree(bp, qindex); 1879 1880 out: 1881 /* unlock */ 1882 BUF_UNLOCK(bp); 1883 } 1884 1885 /* Give pages used by the bp back to the VM system (where possible) */ 1886 static void 1887 vfs_vmio_release(struct buf *bp) 1888 { 1889 vm_object_t obj; 1890 vm_page_t m; 1891 int i; 1892 1893 if ((bp->b_flags & B_UNMAPPED) == 0) { 1894 BUF_CHECK_MAPPED(bp); 1895 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages); 1896 } else 1897 BUF_CHECK_UNMAPPED(bp); 1898 obj = bp->b_bufobj->bo_object; 1899 if (obj != NULL) 1900 VM_OBJECT_WLOCK(obj); 1901 for (i = 0; i < bp->b_npages; i++) { 1902 m = bp->b_pages[i]; 1903 bp->b_pages[i] = NULL; 1904 /* 1905 * In order to keep page LRU ordering consistent, put 1906 * everything on the inactive queue. 1907 */ 1908 vm_page_lock(m); 1909 vm_page_unwire(m, PQ_INACTIVE); 1910 1911 /* 1912 * Might as well free the page if we can and it has 1913 * no valid data. We also free the page if the 1914 * buffer was used for direct I/O 1915 */ 1916 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid) { 1917 if (m->wire_count == 0 && !vm_page_busied(m)) 1918 vm_page_free(m); 1919 } else if (bp->b_flags & B_DIRECT) 1920 vm_page_try_to_free(m); 1921 else if (buf_vm_page_count_severe()) 1922 vm_page_try_to_cache(m); 1923 vm_page_unlock(m); 1924 } 1925 if (obj != NULL) 1926 VM_OBJECT_WUNLOCK(obj); 1927 1928 if (bp->b_bufsize) { 1929 bufspacewakeup(); 1930 bp->b_bufsize = 0; 1931 } 1932 bp->b_npages = 0; 1933 bp->b_flags &= ~B_VMIO; 1934 if (bp->b_vp) 1935 brelvp(bp); 1936 } 1937 1938 /* 1939 * Check to see if a block at a particular lbn is available for a clustered 1940 * write. 1941 */ 1942 static int 1943 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 1944 { 1945 struct buf *bpa; 1946 int match; 1947 1948 match = 0; 1949 1950 /* If the buf isn't in core skip it */ 1951 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 1952 return (0); 1953 1954 /* If the buf is busy we don't want to wait for it */ 1955 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1956 return (0); 1957 1958 /* Only cluster with valid clusterable delayed write buffers */ 1959 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 1960 (B_DELWRI | B_CLUSTEROK)) 1961 goto done; 1962 1963 if (bpa->b_bufsize != size) 1964 goto done; 1965 1966 /* 1967 * Check to see if it is in the expected place on disk and that the 1968 * block has been mapped. 1969 */ 1970 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 1971 match = 1; 1972 done: 1973 BUF_UNLOCK(bpa); 1974 return (match); 1975 } 1976 1977 /* 1978 * vfs_bio_awrite: 1979 * 1980 * Implement clustered async writes for clearing out B_DELWRI buffers. 1981 * This is much better then the old way of writing only one buffer at 1982 * a time. Note that we may not be presented with the buffers in the 1983 * correct order, so we search for the cluster in both directions. 1984 */ 1985 int 1986 vfs_bio_awrite(struct buf *bp) 1987 { 1988 struct bufobj *bo; 1989 int i; 1990 int j; 1991 daddr_t lblkno = bp->b_lblkno; 1992 struct vnode *vp = bp->b_vp; 1993 int ncl; 1994 int nwritten; 1995 int size; 1996 int maxcl; 1997 int gbflags; 1998 1999 bo = &vp->v_bufobj; 2000 gbflags = (bp->b_flags & B_UNMAPPED) != 0 ? GB_UNMAPPED : 0; 2001 /* 2002 * right now we support clustered writing only to regular files. If 2003 * we find a clusterable block we could be in the middle of a cluster 2004 * rather then at the beginning. 2005 */ 2006 if ((vp->v_type == VREG) && 2007 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 2008 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 2009 2010 size = vp->v_mount->mnt_stat.f_iosize; 2011 maxcl = MAXPHYS / size; 2012 2013 BO_RLOCK(bo); 2014 for (i = 1; i < maxcl; i++) 2015 if (vfs_bio_clcheck(vp, size, lblkno + i, 2016 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 2017 break; 2018 2019 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 2020 if (vfs_bio_clcheck(vp, size, lblkno - j, 2021 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 2022 break; 2023 BO_RUNLOCK(bo); 2024 --j; 2025 ncl = i + j; 2026 /* 2027 * this is a possible cluster write 2028 */ 2029 if (ncl != 1) { 2030 BUF_UNLOCK(bp); 2031 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl, 2032 gbflags); 2033 return (nwritten); 2034 } 2035 } 2036 bremfree(bp); 2037 bp->b_flags |= B_ASYNC; 2038 /* 2039 * default (old) behavior, writing out only one block 2040 * 2041 * XXX returns b_bufsize instead of b_bcount for nwritten? 2042 */ 2043 nwritten = bp->b_bufsize; 2044 (void) bwrite(bp); 2045 2046 return (nwritten); 2047 } 2048 2049 static void 2050 setbufkva(struct buf *bp, vm_offset_t addr, int maxsize, int gbflags) 2051 { 2052 2053 KASSERT((bp->b_flags & (B_UNMAPPED | B_KVAALLOC)) == 0 && 2054 bp->b_kvasize == 0, ("call bfreekva(%p)", bp)); 2055 if ((gbflags & GB_UNMAPPED) == 0) { 2056 bp->b_kvabase = (caddr_t)addr; 2057 } else if ((gbflags & GB_KVAALLOC) != 0) { 2058 KASSERT((gbflags & GB_UNMAPPED) != 0, 2059 ("GB_KVAALLOC without GB_UNMAPPED")); 2060 bp->b_kvaalloc = (caddr_t)addr; 2061 bp->b_flags |= B_UNMAPPED | B_KVAALLOC; 2062 atomic_add_long(&unmapped_bufspace, bp->b_kvasize); 2063 } 2064 bp->b_kvasize = maxsize; 2065 } 2066 2067 /* 2068 * Allocate the buffer KVA and set b_kvasize. Also set b_kvabase if 2069 * needed. 2070 */ 2071 static int 2072 allocbufkva(struct buf *bp, int maxsize, int gbflags) 2073 { 2074 vm_offset_t addr; 2075 2076 bfreekva(bp); 2077 addr = 0; 2078 2079 if (vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr)) { 2080 /* 2081 * Buffer map is too fragmented. Request the caller 2082 * to defragment the map. 2083 */ 2084 atomic_add_int(&bufdefragcnt, 1); 2085 return (1); 2086 } 2087 setbufkva(bp, addr, maxsize, gbflags); 2088 atomic_add_long(&bufspace, bp->b_kvasize); 2089 return (0); 2090 } 2091 2092 /* 2093 * Ask the bufdaemon for help, or act as bufdaemon itself, when a 2094 * locked vnode is supplied. 2095 */ 2096 static void 2097 getnewbuf_bufd_help(struct vnode *vp, int gbflags, int slpflag, int slptimeo, 2098 int defrag) 2099 { 2100 struct thread *td; 2101 char *waitmsg; 2102 int error, fl, flags, norunbuf; 2103 2104 mtx_assert(&bqclean, MA_OWNED); 2105 2106 if (defrag) { 2107 flags = VFS_BIO_NEED_BUFSPACE; 2108 waitmsg = "nbufkv"; 2109 } else if (bufspace >= hibufspace) { 2110 waitmsg = "nbufbs"; 2111 flags = VFS_BIO_NEED_BUFSPACE; 2112 } else { 2113 waitmsg = "newbuf"; 2114 flags = VFS_BIO_NEED_ANY; 2115 } 2116 atomic_set_int(&needsbuffer, flags); 2117 mtx_unlock(&bqclean); 2118 2119 bd_speedup(); /* heeeelp */ 2120 if ((gbflags & GB_NOWAIT_BD) != 0) 2121 return; 2122 2123 td = curthread; 2124 rw_wlock(&nblock); 2125 while ((needsbuffer & flags) != 0) { 2126 if (vp != NULL && vp->v_type != VCHR && 2127 (td->td_pflags & TDP_BUFNEED) == 0) { 2128 rw_wunlock(&nblock); 2129 /* 2130 * getblk() is called with a vnode locked, and 2131 * some majority of the dirty buffers may as 2132 * well belong to the vnode. Flushing the 2133 * buffers there would make a progress that 2134 * cannot be achieved by the buf_daemon, that 2135 * cannot lock the vnode. 2136 */ 2137 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) | 2138 (td->td_pflags & TDP_NORUNNINGBUF); 2139 2140 /* 2141 * Play bufdaemon. The getnewbuf() function 2142 * may be called while the thread owns lock 2143 * for another dirty buffer for the same 2144 * vnode, which makes it impossible to use 2145 * VOP_FSYNC() there, due to the buffer lock 2146 * recursion. 2147 */ 2148 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF; 2149 fl = buf_flush(vp, flushbufqtarget); 2150 td->td_pflags &= norunbuf; 2151 rw_wlock(&nblock); 2152 if (fl != 0) 2153 continue; 2154 if ((needsbuffer & flags) == 0) 2155 break; 2156 } 2157 error = rw_sleep(__DEVOLATILE(void *, &needsbuffer), &nblock, 2158 (PRIBIO + 4) | slpflag, waitmsg, slptimeo); 2159 if (error != 0) 2160 break; 2161 } 2162 rw_wunlock(&nblock); 2163 } 2164 2165 static void 2166 getnewbuf_reuse_bp(struct buf *bp, int qindex) 2167 { 2168 2169 CTR6(KTR_BUF, "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d " 2170 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags, 2171 bp->b_kvasize, bp->b_bufsize, qindex); 2172 mtx_assert(&bqclean, MA_NOTOWNED); 2173 2174 /* 2175 * Note: we no longer distinguish between VMIO and non-VMIO 2176 * buffers. 2177 */ 2178 KASSERT((bp->b_flags & B_DELWRI) == 0, 2179 ("delwri buffer %p found in queue %d", bp, qindex)); 2180 2181 if (qindex == QUEUE_CLEAN) { 2182 if (bp->b_flags & B_VMIO) { 2183 bp->b_flags &= ~B_ASYNC; 2184 vfs_vmio_release(bp); 2185 } 2186 if (bp->b_vp != NULL) 2187 brelvp(bp); 2188 } 2189 2190 /* 2191 * Get the rest of the buffer freed up. b_kva* is still valid 2192 * after this operation. 2193 */ 2194 2195 if (bp->b_rcred != NOCRED) { 2196 crfree(bp->b_rcred); 2197 bp->b_rcred = NOCRED; 2198 } 2199 if (bp->b_wcred != NOCRED) { 2200 crfree(bp->b_wcred); 2201 bp->b_wcred = NOCRED; 2202 } 2203 if (!LIST_EMPTY(&bp->b_dep)) 2204 buf_deallocate(bp); 2205 if (bp->b_vflags & BV_BKGRDINPROG) 2206 panic("losing buffer 3"); 2207 KASSERT(bp->b_vp == NULL, ("bp: %p still has vnode %p. qindex: %d", 2208 bp, bp->b_vp, qindex)); 2209 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 2210 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags)); 2211 2212 if (bp->b_bufsize) 2213 allocbuf(bp, 0); 2214 2215 bp->b_flags &= B_UNMAPPED | B_KVAALLOC; 2216 bp->b_ioflags = 0; 2217 bp->b_xflags = 0; 2218 KASSERT((bp->b_flags & B_INFREECNT) == 0, 2219 ("buf %p still counted as free?", bp)); 2220 bp->b_vflags = 0; 2221 bp->b_vp = NULL; 2222 bp->b_blkno = bp->b_lblkno = 0; 2223 bp->b_offset = NOOFFSET; 2224 bp->b_iodone = 0; 2225 bp->b_error = 0; 2226 bp->b_resid = 0; 2227 bp->b_bcount = 0; 2228 bp->b_npages = 0; 2229 bp->b_dirtyoff = bp->b_dirtyend = 0; 2230 bp->b_bufobj = NULL; 2231 bp->b_pin_count = 0; 2232 bp->b_fsprivate1 = NULL; 2233 bp->b_fsprivate2 = NULL; 2234 bp->b_fsprivate3 = NULL; 2235 2236 LIST_INIT(&bp->b_dep); 2237 } 2238 2239 static int flushingbufs; 2240 2241 static struct buf * 2242 getnewbuf_scan(int maxsize, int defrag, int unmapped, int metadata) 2243 { 2244 struct buf *bp, *nbp; 2245 int nqindex, qindex, pass; 2246 2247 KASSERT(!unmapped || !defrag, ("both unmapped and defrag")); 2248 2249 pass = 1; 2250 restart: 2251 atomic_add_int(&getnewbufrestarts, 1); 2252 2253 /* 2254 * Setup for scan. If we do not have enough free buffers, 2255 * we setup a degenerate case that immediately fails. Note 2256 * that if we are specially marked process, we are allowed to 2257 * dip into our reserves. 2258 * 2259 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 2260 * for the allocation of the mapped buffer. For unmapped, the 2261 * easiest is to start with EMPTY outright. 2262 * 2263 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 2264 * However, there are a number of cases (defragging, reusing, ...) 2265 * where we cannot backup. 2266 */ 2267 nbp = NULL; 2268 mtx_lock(&bqclean); 2269 if (!defrag && unmapped) { 2270 nqindex = QUEUE_EMPTY; 2271 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 2272 } 2273 if (nbp == NULL) { 2274 nqindex = QUEUE_EMPTYKVA; 2275 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 2276 } 2277 2278 /* 2279 * If no EMPTYKVA buffers and we are either defragging or 2280 * reusing, locate a CLEAN buffer to free or reuse. If 2281 * bufspace useage is low skip this step so we can allocate a 2282 * new buffer. 2283 */ 2284 if (nbp == NULL && (defrag || bufspace >= lobufspace)) { 2285 nqindex = QUEUE_CLEAN; 2286 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2287 } 2288 2289 /* 2290 * If we could not find or were not allowed to reuse a CLEAN 2291 * buffer, check to see if it is ok to use an EMPTY buffer. 2292 * We can only use an EMPTY buffer if allocating its KVA would 2293 * not otherwise run us out of buffer space. No KVA is needed 2294 * for the unmapped allocation. 2295 */ 2296 if (nbp == NULL && defrag == 0 && (bufspace + maxsize < hibufspace || 2297 metadata)) { 2298 nqindex = QUEUE_EMPTY; 2299 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 2300 } 2301 2302 /* 2303 * All available buffers might be clean, retry ignoring the 2304 * lobufspace as the last resort. 2305 */ 2306 if (nbp == NULL && !TAILQ_EMPTY(&bufqueues[QUEUE_CLEAN])) { 2307 nqindex = QUEUE_CLEAN; 2308 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2309 } 2310 2311 /* 2312 * Run scan, possibly freeing data and/or kva mappings on the fly 2313 * depending. 2314 */ 2315 while ((bp = nbp) != NULL) { 2316 qindex = nqindex; 2317 2318 /* 2319 * Calculate next bp (we can only use it if we do not 2320 * block or do other fancy things). 2321 */ 2322 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 2323 switch (qindex) { 2324 case QUEUE_EMPTY: 2325 nqindex = QUEUE_EMPTYKVA; 2326 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 2327 if (nbp != NULL) 2328 break; 2329 /* FALLTHROUGH */ 2330 case QUEUE_EMPTYKVA: 2331 nqindex = QUEUE_CLEAN; 2332 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2333 if (nbp != NULL) 2334 break; 2335 /* FALLTHROUGH */ 2336 case QUEUE_CLEAN: 2337 if (metadata && pass == 1) { 2338 pass = 2; 2339 nqindex = QUEUE_EMPTY; 2340 nbp = TAILQ_FIRST( 2341 &bufqueues[QUEUE_EMPTY]); 2342 } 2343 /* 2344 * nbp is NULL. 2345 */ 2346 break; 2347 } 2348 } 2349 /* 2350 * If we are defragging then we need a buffer with 2351 * b_kvasize != 0. XXX this situation should no longer 2352 * occur, if defrag is non-zero the buffer's b_kvasize 2353 * should also be non-zero at this point. XXX 2354 */ 2355 if (defrag && bp->b_kvasize == 0) { 2356 printf("Warning: defrag empty buffer %p\n", bp); 2357 continue; 2358 } 2359 2360 /* 2361 * Start freeing the bp. This is somewhat involved. nbp 2362 * remains valid only for QUEUE_EMPTY[KVA] bp's. 2363 */ 2364 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2365 continue; 2366 /* 2367 * BKGRDINPROG can only be set with the buf and bufobj 2368 * locks both held. We tolerate a race to clear it here. 2369 */ 2370 if (bp->b_vflags & BV_BKGRDINPROG) { 2371 BUF_UNLOCK(bp); 2372 continue; 2373 } 2374 2375 KASSERT(bp->b_qindex == qindex, 2376 ("getnewbuf: inconsistent queue %d bp %p", qindex, bp)); 2377 2378 bremfreel(bp); 2379 mtx_unlock(&bqclean); 2380 /* 2381 * NOTE: nbp is now entirely invalid. We can only restart 2382 * the scan from this point on. 2383 */ 2384 2385 getnewbuf_reuse_bp(bp, qindex); 2386 mtx_assert(&bqclean, MA_NOTOWNED); 2387 2388 /* 2389 * If we are defragging then free the buffer. 2390 */ 2391 if (defrag) { 2392 bp->b_flags |= B_INVAL; 2393 bfreekva(bp); 2394 brelse(bp); 2395 defrag = 0; 2396 goto restart; 2397 } 2398 2399 /* 2400 * Notify any waiters for the buffer lock about 2401 * identity change by freeing the buffer. 2402 */ 2403 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp)) { 2404 bp->b_flags |= B_INVAL; 2405 bfreekva(bp); 2406 brelse(bp); 2407 goto restart; 2408 } 2409 2410 if (metadata) 2411 break; 2412 2413 /* 2414 * If we are overcomitted then recover the buffer and its 2415 * KVM space. This occurs in rare situations when multiple 2416 * processes are blocked in getnewbuf() or allocbuf(). 2417 */ 2418 if (bufspace >= hibufspace) 2419 flushingbufs = 1; 2420 if (flushingbufs && bp->b_kvasize != 0) { 2421 bp->b_flags |= B_INVAL; 2422 bfreekva(bp); 2423 brelse(bp); 2424 goto restart; 2425 } 2426 if (bufspace < lobufspace) 2427 flushingbufs = 0; 2428 break; 2429 } 2430 return (bp); 2431 } 2432 2433 /* 2434 * getnewbuf: 2435 * 2436 * Find and initialize a new buffer header, freeing up existing buffers 2437 * in the bufqueues as necessary. The new buffer is returned locked. 2438 * 2439 * Important: B_INVAL is not set. If the caller wishes to throw the 2440 * buffer away, the caller must set B_INVAL prior to calling brelse(). 2441 * 2442 * We block if: 2443 * We have insufficient buffer headers 2444 * We have insufficient buffer space 2445 * buffer_arena is too fragmented ( space reservation fails ) 2446 * If we have to flush dirty buffers ( but we try to avoid this ) 2447 */ 2448 static struct buf * 2449 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int size, int maxsize, 2450 int gbflags) 2451 { 2452 struct buf *bp; 2453 int defrag, metadata; 2454 2455 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 2456 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 2457 if (!unmapped_buf_allowed) 2458 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC); 2459 2460 defrag = 0; 2461 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 || 2462 vp->v_type == VCHR) 2463 metadata = 1; 2464 else 2465 metadata = 0; 2466 /* 2467 * We can't afford to block since we might be holding a vnode lock, 2468 * which may prevent system daemons from running. We deal with 2469 * low-memory situations by proactively returning memory and running 2470 * async I/O rather then sync I/O. 2471 */ 2472 atomic_add_int(&getnewbufcalls, 1); 2473 atomic_subtract_int(&getnewbufrestarts, 1); 2474 restart: 2475 bp = getnewbuf_scan(maxsize, defrag, (gbflags & (GB_UNMAPPED | 2476 GB_KVAALLOC)) == GB_UNMAPPED, metadata); 2477 if (bp != NULL) 2478 defrag = 0; 2479 2480 /* 2481 * If we exhausted our list, sleep as appropriate. We may have to 2482 * wakeup various daemons and write out some dirty buffers. 2483 * 2484 * Generally we are sleeping due to insufficient buffer space. 2485 */ 2486 if (bp == NULL) { 2487 mtx_assert(&bqclean, MA_OWNED); 2488 getnewbuf_bufd_help(vp, gbflags, slpflag, slptimeo, defrag); 2489 mtx_assert(&bqclean, MA_NOTOWNED); 2490 } else if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == GB_UNMAPPED) { 2491 mtx_assert(&bqclean, MA_NOTOWNED); 2492 2493 bfreekva(bp); 2494 bp->b_flags |= B_UNMAPPED; 2495 bp->b_kvabase = bp->b_data = unmapped_buf; 2496 bp->b_kvasize = maxsize; 2497 atomic_add_long(&bufspace, bp->b_kvasize); 2498 atomic_add_long(&unmapped_bufspace, bp->b_kvasize); 2499 atomic_add_int(&bufreusecnt, 1); 2500 } else { 2501 mtx_assert(&bqclean, MA_NOTOWNED); 2502 2503 /* 2504 * We finally have a valid bp. We aren't quite out of the 2505 * woods, we still have to reserve kva space. In order 2506 * to keep fragmentation sane we only allocate kva in 2507 * BKVASIZE chunks. 2508 */ 2509 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2510 2511 if (maxsize != bp->b_kvasize || (bp->b_flags & (B_UNMAPPED | 2512 B_KVAALLOC)) == B_UNMAPPED) { 2513 if (allocbufkva(bp, maxsize, gbflags)) { 2514 defrag = 1; 2515 bp->b_flags |= B_INVAL; 2516 brelse(bp); 2517 goto restart; 2518 } 2519 atomic_add_int(&bufreusecnt, 1); 2520 } else if ((bp->b_flags & B_KVAALLOC) != 0 && 2521 (gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == 0) { 2522 /* 2523 * If the reused buffer has KVA allocated, 2524 * reassign b_kvaalloc to b_kvabase. 2525 */ 2526 bp->b_kvabase = bp->b_kvaalloc; 2527 bp->b_flags &= ~B_KVAALLOC; 2528 atomic_subtract_long(&unmapped_bufspace, 2529 bp->b_kvasize); 2530 atomic_add_int(&bufreusecnt, 1); 2531 } else if ((bp->b_flags & (B_UNMAPPED | B_KVAALLOC)) == 0 && 2532 (gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == (GB_UNMAPPED | 2533 GB_KVAALLOC)) { 2534 /* 2535 * The case of reused buffer already have KVA 2536 * mapped, but the request is for unmapped 2537 * buffer with KVA allocated. 2538 */ 2539 bp->b_kvaalloc = bp->b_kvabase; 2540 bp->b_data = bp->b_kvabase = unmapped_buf; 2541 bp->b_flags |= B_UNMAPPED | B_KVAALLOC; 2542 atomic_add_long(&unmapped_bufspace, 2543 bp->b_kvasize); 2544 atomic_add_int(&bufreusecnt, 1); 2545 } 2546 if ((gbflags & GB_UNMAPPED) == 0) { 2547 bp->b_saveaddr = bp->b_kvabase; 2548 bp->b_data = bp->b_saveaddr; 2549 bp->b_flags &= ~B_UNMAPPED; 2550 BUF_CHECK_MAPPED(bp); 2551 } 2552 } 2553 return (bp); 2554 } 2555 2556 /* 2557 * buf_daemon: 2558 * 2559 * buffer flushing daemon. Buffers are normally flushed by the 2560 * update daemon but if it cannot keep up this process starts to 2561 * take the load in an attempt to prevent getnewbuf() from blocking. 2562 */ 2563 2564 static struct kproc_desc buf_kp = { 2565 "bufdaemon", 2566 buf_daemon, 2567 &bufdaemonproc 2568 }; 2569 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 2570 2571 static int 2572 buf_flush(struct vnode *vp, int target) 2573 { 2574 int flushed; 2575 2576 flushed = flushbufqueues(vp, target, 0); 2577 if (flushed == 0) { 2578 /* 2579 * Could not find any buffers without rollback 2580 * dependencies, so just write the first one 2581 * in the hopes of eventually making progress. 2582 */ 2583 if (vp != NULL && target > 2) 2584 target /= 2; 2585 flushbufqueues(vp, target, 1); 2586 } 2587 return (flushed); 2588 } 2589 2590 static void 2591 buf_daemon() 2592 { 2593 int lodirty; 2594 2595 /* 2596 * This process needs to be suspended prior to shutdown sync. 2597 */ 2598 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2599 SHUTDOWN_PRI_LAST); 2600 2601 /* 2602 * This process is allowed to take the buffer cache to the limit 2603 */ 2604 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 2605 mtx_lock(&bdlock); 2606 for (;;) { 2607 bd_request = 0; 2608 mtx_unlock(&bdlock); 2609 2610 kproc_suspend_check(bufdaemonproc); 2611 lodirty = lodirtybuffers; 2612 if (bd_speedupreq) { 2613 lodirty = numdirtybuffers / 2; 2614 bd_speedupreq = 0; 2615 } 2616 /* 2617 * Do the flush. Limit the amount of in-transit I/O we 2618 * allow to build up, otherwise we would completely saturate 2619 * the I/O system. 2620 */ 2621 while (numdirtybuffers > lodirty) { 2622 if (buf_flush(NULL, numdirtybuffers - lodirty) == 0) 2623 break; 2624 kern_yield(PRI_USER); 2625 } 2626 2627 /* 2628 * Only clear bd_request if we have reached our low water 2629 * mark. The buf_daemon normally waits 1 second and 2630 * then incrementally flushes any dirty buffers that have 2631 * built up, within reason. 2632 * 2633 * If we were unable to hit our low water mark and couldn't 2634 * find any flushable buffers, we sleep for a short period 2635 * to avoid endless loops on unlockable buffers. 2636 */ 2637 mtx_lock(&bdlock); 2638 if (numdirtybuffers <= lodirtybuffers) { 2639 /* 2640 * We reached our low water mark, reset the 2641 * request and sleep until we are needed again. 2642 * The sleep is just so the suspend code works. 2643 */ 2644 bd_request = 0; 2645 /* 2646 * Do an extra wakeup in case dirty threshold 2647 * changed via sysctl and the explicit transition 2648 * out of shortfall was missed. 2649 */ 2650 bdirtywakeup(); 2651 if (runningbufspace <= lorunningspace) 2652 runningwakeup(); 2653 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 2654 } else { 2655 /* 2656 * We couldn't find any flushable dirty buffers but 2657 * still have too many dirty buffers, we 2658 * have to sleep and try again. (rare) 2659 */ 2660 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 2661 } 2662 } 2663 } 2664 2665 /* 2666 * flushbufqueues: 2667 * 2668 * Try to flush a buffer in the dirty queue. We must be careful to 2669 * free up B_INVAL buffers instead of write them, which NFS is 2670 * particularly sensitive to. 2671 */ 2672 static int flushwithdeps = 0; 2673 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 2674 0, "Number of buffers flushed with dependecies that require rollbacks"); 2675 2676 static int 2677 flushbufqueues(struct vnode *lvp, int target, int flushdeps) 2678 { 2679 struct buf *sentinel; 2680 struct vnode *vp; 2681 struct mount *mp; 2682 struct buf *bp; 2683 int hasdeps; 2684 int flushed; 2685 int queue; 2686 int error; 2687 bool unlock; 2688 2689 flushed = 0; 2690 queue = QUEUE_DIRTY; 2691 bp = NULL; 2692 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 2693 sentinel->b_qindex = QUEUE_SENTINEL; 2694 mtx_lock(&bqdirty); 2695 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist); 2696 mtx_unlock(&bqdirty); 2697 while (flushed != target) { 2698 maybe_yield(); 2699 mtx_lock(&bqdirty); 2700 bp = TAILQ_NEXT(sentinel, b_freelist); 2701 if (bp != NULL) { 2702 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2703 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel, 2704 b_freelist); 2705 } else { 2706 mtx_unlock(&bqdirty); 2707 break; 2708 } 2709 /* 2710 * Skip sentinels inserted by other invocations of the 2711 * flushbufqueues(), taking care to not reorder them. 2712 * 2713 * Only flush the buffers that belong to the 2714 * vnode locked by the curthread. 2715 */ 2716 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL && 2717 bp->b_vp != lvp)) { 2718 mtx_unlock(&bqdirty); 2719 continue; 2720 } 2721 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL); 2722 mtx_unlock(&bqdirty); 2723 if (error != 0) 2724 continue; 2725 if (bp->b_pin_count > 0) { 2726 BUF_UNLOCK(bp); 2727 continue; 2728 } 2729 /* 2730 * BKGRDINPROG can only be set with the buf and bufobj 2731 * locks both held. We tolerate a race to clear it here. 2732 */ 2733 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 2734 (bp->b_flags & B_DELWRI) == 0) { 2735 BUF_UNLOCK(bp); 2736 continue; 2737 } 2738 if (bp->b_flags & B_INVAL) { 2739 bremfreef(bp); 2740 brelse(bp); 2741 flushed++; 2742 continue; 2743 } 2744 2745 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 2746 if (flushdeps == 0) { 2747 BUF_UNLOCK(bp); 2748 continue; 2749 } 2750 hasdeps = 1; 2751 } else 2752 hasdeps = 0; 2753 /* 2754 * We must hold the lock on a vnode before writing 2755 * one of its buffers. Otherwise we may confuse, or 2756 * in the case of a snapshot vnode, deadlock the 2757 * system. 2758 * 2759 * The lock order here is the reverse of the normal 2760 * of vnode followed by buf lock. This is ok because 2761 * the NOWAIT will prevent deadlock. 2762 */ 2763 vp = bp->b_vp; 2764 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 2765 BUF_UNLOCK(bp); 2766 continue; 2767 } 2768 if (lvp == NULL) { 2769 unlock = true; 2770 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT); 2771 } else { 2772 ASSERT_VOP_LOCKED(vp, "getbuf"); 2773 unlock = false; 2774 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 : 2775 vn_lock(vp, LK_TRYUPGRADE); 2776 } 2777 if (error == 0) { 2778 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 2779 bp, bp->b_vp, bp->b_flags); 2780 if (curproc == bufdaemonproc) { 2781 vfs_bio_awrite(bp); 2782 } else { 2783 bremfree(bp); 2784 bwrite(bp); 2785 notbufdflushes++; 2786 } 2787 vn_finished_write(mp); 2788 if (unlock) 2789 VOP_UNLOCK(vp, 0); 2790 flushwithdeps += hasdeps; 2791 flushed++; 2792 2793 /* 2794 * Sleeping on runningbufspace while holding 2795 * vnode lock leads to deadlock. 2796 */ 2797 if (curproc == bufdaemonproc && 2798 runningbufspace > hirunningspace) 2799 waitrunningbufspace(); 2800 continue; 2801 } 2802 vn_finished_write(mp); 2803 BUF_UNLOCK(bp); 2804 } 2805 mtx_lock(&bqdirty); 2806 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2807 mtx_unlock(&bqdirty); 2808 free(sentinel, M_TEMP); 2809 return (flushed); 2810 } 2811 2812 /* 2813 * Check to see if a block is currently memory resident. 2814 */ 2815 struct buf * 2816 incore(struct bufobj *bo, daddr_t blkno) 2817 { 2818 struct buf *bp; 2819 2820 BO_RLOCK(bo); 2821 bp = gbincore(bo, blkno); 2822 BO_RUNLOCK(bo); 2823 return (bp); 2824 } 2825 2826 /* 2827 * Returns true if no I/O is needed to access the 2828 * associated VM object. This is like incore except 2829 * it also hunts around in the VM system for the data. 2830 */ 2831 2832 static int 2833 inmem(struct vnode * vp, daddr_t blkno) 2834 { 2835 vm_object_t obj; 2836 vm_offset_t toff, tinc, size; 2837 vm_page_t m; 2838 vm_ooffset_t off; 2839 2840 ASSERT_VOP_LOCKED(vp, "inmem"); 2841 2842 if (incore(&vp->v_bufobj, blkno)) 2843 return 1; 2844 if (vp->v_mount == NULL) 2845 return 0; 2846 obj = vp->v_object; 2847 if (obj == NULL) 2848 return (0); 2849 2850 size = PAGE_SIZE; 2851 if (size > vp->v_mount->mnt_stat.f_iosize) 2852 size = vp->v_mount->mnt_stat.f_iosize; 2853 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2854 2855 VM_OBJECT_RLOCK(obj); 2856 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2857 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2858 if (!m) 2859 goto notinmem; 2860 tinc = size; 2861 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2862 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2863 if (vm_page_is_valid(m, 2864 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2865 goto notinmem; 2866 } 2867 VM_OBJECT_RUNLOCK(obj); 2868 return 1; 2869 2870 notinmem: 2871 VM_OBJECT_RUNLOCK(obj); 2872 return (0); 2873 } 2874 2875 /* 2876 * Set the dirty range for a buffer based on the status of the dirty 2877 * bits in the pages comprising the buffer. The range is limited 2878 * to the size of the buffer. 2879 * 2880 * Tell the VM system that the pages associated with this buffer 2881 * are clean. This is used for delayed writes where the data is 2882 * going to go to disk eventually without additional VM intevention. 2883 * 2884 * Note that while we only really need to clean through to b_bcount, we 2885 * just go ahead and clean through to b_bufsize. 2886 */ 2887 static void 2888 vfs_clean_pages_dirty_buf(struct buf *bp) 2889 { 2890 vm_ooffset_t foff, noff, eoff; 2891 vm_page_t m; 2892 int i; 2893 2894 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 2895 return; 2896 2897 foff = bp->b_offset; 2898 KASSERT(bp->b_offset != NOOFFSET, 2899 ("vfs_clean_pages_dirty_buf: no buffer offset")); 2900 2901 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 2902 vfs_drain_busy_pages(bp); 2903 vfs_setdirty_locked_object(bp); 2904 for (i = 0; i < bp->b_npages; i++) { 2905 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2906 eoff = noff; 2907 if (eoff > bp->b_offset + bp->b_bufsize) 2908 eoff = bp->b_offset + bp->b_bufsize; 2909 m = bp->b_pages[i]; 2910 vfs_page_set_validclean(bp, foff, m); 2911 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 2912 foff = noff; 2913 } 2914 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 2915 } 2916 2917 static void 2918 vfs_setdirty_locked_object(struct buf *bp) 2919 { 2920 vm_object_t object; 2921 int i; 2922 2923 object = bp->b_bufobj->bo_object; 2924 VM_OBJECT_ASSERT_WLOCKED(object); 2925 2926 /* 2927 * We qualify the scan for modified pages on whether the 2928 * object has been flushed yet. 2929 */ 2930 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) { 2931 vm_offset_t boffset; 2932 vm_offset_t eoffset; 2933 2934 /* 2935 * test the pages to see if they have been modified directly 2936 * by users through the VM system. 2937 */ 2938 for (i = 0; i < bp->b_npages; i++) 2939 vm_page_test_dirty(bp->b_pages[i]); 2940 2941 /* 2942 * Calculate the encompassing dirty range, boffset and eoffset, 2943 * (eoffset - boffset) bytes. 2944 */ 2945 2946 for (i = 0; i < bp->b_npages; i++) { 2947 if (bp->b_pages[i]->dirty) 2948 break; 2949 } 2950 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2951 2952 for (i = bp->b_npages - 1; i >= 0; --i) { 2953 if (bp->b_pages[i]->dirty) { 2954 break; 2955 } 2956 } 2957 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2958 2959 /* 2960 * Fit it to the buffer. 2961 */ 2962 2963 if (eoffset > bp->b_bcount) 2964 eoffset = bp->b_bcount; 2965 2966 /* 2967 * If we have a good dirty range, merge with the existing 2968 * dirty range. 2969 */ 2970 2971 if (boffset < eoffset) { 2972 if (bp->b_dirtyoff > boffset) 2973 bp->b_dirtyoff = boffset; 2974 if (bp->b_dirtyend < eoffset) 2975 bp->b_dirtyend = eoffset; 2976 } 2977 } 2978 } 2979 2980 /* 2981 * Allocate the KVA mapping for an existing buffer. It handles the 2982 * cases of both B_UNMAPPED buffer, and buffer with the preallocated 2983 * KVA which is not mapped (B_KVAALLOC). 2984 */ 2985 static void 2986 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags) 2987 { 2988 struct buf *scratch_bp; 2989 int bsize, maxsize, need_mapping, need_kva; 2990 off_t offset; 2991 2992 need_mapping = (bp->b_flags & B_UNMAPPED) != 0 && 2993 (gbflags & GB_UNMAPPED) == 0; 2994 need_kva = (bp->b_flags & (B_KVAALLOC | B_UNMAPPED)) == B_UNMAPPED && 2995 (gbflags & GB_KVAALLOC) != 0; 2996 if (!need_mapping && !need_kva) 2997 return; 2998 2999 BUF_CHECK_UNMAPPED(bp); 3000 3001 if (need_mapping && (bp->b_flags & B_KVAALLOC) != 0) { 3002 /* 3003 * Buffer is not mapped, but the KVA was already 3004 * reserved at the time of the instantiation. Use the 3005 * allocated space. 3006 */ 3007 bp->b_flags &= ~B_KVAALLOC; 3008 KASSERT(bp->b_kvaalloc != 0, ("kvaalloc == 0")); 3009 bp->b_kvabase = bp->b_kvaalloc; 3010 atomic_subtract_long(&unmapped_bufspace, bp->b_kvasize); 3011 goto has_addr; 3012 } 3013 3014 /* 3015 * Calculate the amount of the address space we would reserve 3016 * if the buffer was mapped. 3017 */ 3018 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize; 3019 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3020 offset = blkno * bsize; 3021 maxsize = size + (offset & PAGE_MASK); 3022 maxsize = imax(maxsize, bsize); 3023 3024 mapping_loop: 3025 if (allocbufkva(bp, maxsize, gbflags)) { 3026 /* 3027 * Request defragmentation. getnewbuf() returns us the 3028 * allocated space by the scratch buffer KVA. 3029 */ 3030 scratch_bp = getnewbuf(bp->b_vp, 0, 0, size, maxsize, gbflags | 3031 (GB_UNMAPPED | GB_KVAALLOC)); 3032 if (scratch_bp == NULL) { 3033 if ((gbflags & GB_NOWAIT_BD) != 0) { 3034 /* 3035 * XXXKIB: defragmentation cannot 3036 * succeed, not sure what else to do. 3037 */ 3038 panic("GB_NOWAIT_BD and B_UNMAPPED %p", bp); 3039 } 3040 atomic_add_int(&mappingrestarts, 1); 3041 goto mapping_loop; 3042 } 3043 KASSERT((scratch_bp->b_flags & B_KVAALLOC) != 0, 3044 ("scratch bp !B_KVAALLOC %p", scratch_bp)); 3045 setbufkva(bp, (vm_offset_t)scratch_bp->b_kvaalloc, 3046 scratch_bp->b_kvasize, gbflags); 3047 3048 /* Get rid of the scratch buffer. */ 3049 scratch_bp->b_kvasize = 0; 3050 scratch_bp->b_flags |= B_INVAL; 3051 scratch_bp->b_flags &= ~(B_UNMAPPED | B_KVAALLOC); 3052 brelse(scratch_bp); 3053 } 3054 if (!need_mapping) 3055 return; 3056 3057 has_addr: 3058 bp->b_saveaddr = bp->b_kvabase; 3059 bp->b_data = bp->b_saveaddr; /* b_offset is handled by bpmap_qenter */ 3060 bp->b_flags &= ~B_UNMAPPED; 3061 BUF_CHECK_MAPPED(bp); 3062 bpmap_qenter(bp); 3063 } 3064 3065 /* 3066 * getblk: 3067 * 3068 * Get a block given a specified block and offset into a file/device. 3069 * The buffers B_DONE bit will be cleared on return, making it almost 3070 * ready for an I/O initiation. B_INVAL may or may not be set on 3071 * return. The caller should clear B_INVAL prior to initiating a 3072 * READ. 3073 * 3074 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 3075 * an existing buffer. 3076 * 3077 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 3078 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 3079 * and then cleared based on the backing VM. If the previous buffer is 3080 * non-0-sized but invalid, B_CACHE will be cleared. 3081 * 3082 * If getblk() must create a new buffer, the new buffer is returned with 3083 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 3084 * case it is returned with B_INVAL clear and B_CACHE set based on the 3085 * backing VM. 3086 * 3087 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 3088 * B_CACHE bit is clear. 3089 * 3090 * What this means, basically, is that the caller should use B_CACHE to 3091 * determine whether the buffer is fully valid or not and should clear 3092 * B_INVAL prior to issuing a read. If the caller intends to validate 3093 * the buffer by loading its data area with something, the caller needs 3094 * to clear B_INVAL. If the caller does this without issuing an I/O, 3095 * the caller should set B_CACHE ( as an optimization ), else the caller 3096 * should issue the I/O and biodone() will set B_CACHE if the I/O was 3097 * a write attempt or if it was a successfull read. If the caller 3098 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 3099 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 3100 */ 3101 struct buf * 3102 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3103 int flags) 3104 { 3105 struct buf *bp; 3106 struct bufobj *bo; 3107 int bsize, error, maxsize, vmio; 3108 off_t offset; 3109 3110 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 3111 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3112 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3113 ASSERT_VOP_LOCKED(vp, "getblk"); 3114 if (size > MAXBCACHEBUF) 3115 panic("getblk: size(%d) > MAXBCACHEBUF(%d)\n", size, 3116 MAXBCACHEBUF); 3117 if (!unmapped_buf_allowed) 3118 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3119 3120 bo = &vp->v_bufobj; 3121 loop: 3122 BO_RLOCK(bo); 3123 bp = gbincore(bo, blkno); 3124 if (bp != NULL) { 3125 int lockflags; 3126 /* 3127 * Buffer is in-core. If the buffer is not busy nor managed, 3128 * it must be on a queue. 3129 */ 3130 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 3131 3132 if (flags & GB_LOCK_NOWAIT) 3133 lockflags |= LK_NOWAIT; 3134 3135 error = BUF_TIMELOCK(bp, lockflags, 3136 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo); 3137 3138 /* 3139 * If we slept and got the lock we have to restart in case 3140 * the buffer changed identities. 3141 */ 3142 if (error == ENOLCK) 3143 goto loop; 3144 /* We timed out or were interrupted. */ 3145 else if (error) 3146 return (NULL); 3147 /* If recursed, assume caller knows the rules. */ 3148 else if (BUF_LOCKRECURSED(bp)) 3149 goto end; 3150 3151 /* 3152 * The buffer is locked. B_CACHE is cleared if the buffer is 3153 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 3154 * and for a VMIO buffer B_CACHE is adjusted according to the 3155 * backing VM cache. 3156 */ 3157 if (bp->b_flags & B_INVAL) 3158 bp->b_flags &= ~B_CACHE; 3159 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 3160 bp->b_flags |= B_CACHE; 3161 if (bp->b_flags & B_MANAGED) 3162 MPASS(bp->b_qindex == QUEUE_NONE); 3163 else 3164 bremfree(bp); 3165 3166 /* 3167 * check for size inconsistencies for non-VMIO case. 3168 */ 3169 if (bp->b_bcount != size) { 3170 if ((bp->b_flags & B_VMIO) == 0 || 3171 (size > bp->b_kvasize)) { 3172 if (bp->b_flags & B_DELWRI) { 3173 /* 3174 * If buffer is pinned and caller does 3175 * not want sleep waiting for it to be 3176 * unpinned, bail out 3177 * */ 3178 if (bp->b_pin_count > 0) { 3179 if (flags & GB_LOCK_NOWAIT) { 3180 bqrelse(bp); 3181 return (NULL); 3182 } else { 3183 bunpin_wait(bp); 3184 } 3185 } 3186 bp->b_flags |= B_NOCACHE; 3187 bwrite(bp); 3188 } else { 3189 if (LIST_EMPTY(&bp->b_dep)) { 3190 bp->b_flags |= B_RELBUF; 3191 brelse(bp); 3192 } else { 3193 bp->b_flags |= B_NOCACHE; 3194 bwrite(bp); 3195 } 3196 } 3197 goto loop; 3198 } 3199 } 3200 3201 /* 3202 * Handle the case of unmapped buffer which should 3203 * become mapped, or the buffer for which KVA 3204 * reservation is requested. 3205 */ 3206 bp_unmapped_get_kva(bp, blkno, size, flags); 3207 3208 /* 3209 * If the size is inconsistant in the VMIO case, we can resize 3210 * the buffer. This might lead to B_CACHE getting set or 3211 * cleared. If the size has not changed, B_CACHE remains 3212 * unchanged from its previous state. 3213 */ 3214 if (bp->b_bcount != size) 3215 allocbuf(bp, size); 3216 3217 KASSERT(bp->b_offset != NOOFFSET, 3218 ("getblk: no buffer offset")); 3219 3220 /* 3221 * A buffer with B_DELWRI set and B_CACHE clear must 3222 * be committed before we can return the buffer in 3223 * order to prevent the caller from issuing a read 3224 * ( due to B_CACHE not being set ) and overwriting 3225 * it. 3226 * 3227 * Most callers, including NFS and FFS, need this to 3228 * operate properly either because they assume they 3229 * can issue a read if B_CACHE is not set, or because 3230 * ( for example ) an uncached B_DELWRI might loop due 3231 * to softupdates re-dirtying the buffer. In the latter 3232 * case, B_CACHE is set after the first write completes, 3233 * preventing further loops. 3234 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 3235 * above while extending the buffer, we cannot allow the 3236 * buffer to remain with B_CACHE set after the write 3237 * completes or it will represent a corrupt state. To 3238 * deal with this we set B_NOCACHE to scrap the buffer 3239 * after the write. 3240 * 3241 * We might be able to do something fancy, like setting 3242 * B_CACHE in bwrite() except if B_DELWRI is already set, 3243 * so the below call doesn't set B_CACHE, but that gets real 3244 * confusing. This is much easier. 3245 */ 3246 3247 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 3248 bp->b_flags |= B_NOCACHE; 3249 bwrite(bp); 3250 goto loop; 3251 } 3252 bp->b_flags &= ~B_DONE; 3253 } else { 3254 /* 3255 * Buffer is not in-core, create new buffer. The buffer 3256 * returned by getnewbuf() is locked. Note that the returned 3257 * buffer is also considered valid (not marked B_INVAL). 3258 */ 3259 BO_RUNLOCK(bo); 3260 /* 3261 * If the user does not want us to create the buffer, bail out 3262 * here. 3263 */ 3264 if (flags & GB_NOCREAT) 3265 return NULL; 3266 if (numfreebuffers == 0 && TD_IS_IDLETHREAD(curthread)) 3267 return NULL; 3268 3269 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize; 3270 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3271 offset = blkno * bsize; 3272 vmio = vp->v_object != NULL; 3273 if (vmio) { 3274 maxsize = size + (offset & PAGE_MASK); 3275 } else { 3276 maxsize = size; 3277 /* Do not allow non-VMIO notmapped buffers. */ 3278 flags &= ~GB_UNMAPPED; 3279 } 3280 maxsize = imax(maxsize, bsize); 3281 3282 bp = getnewbuf(vp, slpflag, slptimeo, size, maxsize, flags); 3283 if (bp == NULL) { 3284 if (slpflag || slptimeo) 3285 return NULL; 3286 goto loop; 3287 } 3288 3289 /* 3290 * This code is used to make sure that a buffer is not 3291 * created while the getnewbuf routine is blocked. 3292 * This can be a problem whether the vnode is locked or not. 3293 * If the buffer is created out from under us, we have to 3294 * throw away the one we just created. 3295 * 3296 * Note: this must occur before we associate the buffer 3297 * with the vp especially considering limitations in 3298 * the splay tree implementation when dealing with duplicate 3299 * lblkno's. 3300 */ 3301 BO_LOCK(bo); 3302 if (gbincore(bo, blkno)) { 3303 BO_UNLOCK(bo); 3304 bp->b_flags |= B_INVAL; 3305 brelse(bp); 3306 goto loop; 3307 } 3308 3309 /* 3310 * Insert the buffer into the hash, so that it can 3311 * be found by incore. 3312 */ 3313 bp->b_blkno = bp->b_lblkno = blkno; 3314 bp->b_offset = offset; 3315 bgetvp(vp, bp); 3316 BO_UNLOCK(bo); 3317 3318 /* 3319 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 3320 * buffer size starts out as 0, B_CACHE will be set by 3321 * allocbuf() for the VMIO case prior to it testing the 3322 * backing store for validity. 3323 */ 3324 3325 if (vmio) { 3326 bp->b_flags |= B_VMIO; 3327 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 3328 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 3329 bp, vp->v_object, bp->b_bufobj->bo_object)); 3330 } else { 3331 bp->b_flags &= ~B_VMIO; 3332 KASSERT(bp->b_bufobj->bo_object == NULL, 3333 ("ARGH! has b_bufobj->bo_object %p %p\n", 3334 bp, bp->b_bufobj->bo_object)); 3335 BUF_CHECK_MAPPED(bp); 3336 } 3337 3338 allocbuf(bp, size); 3339 bp->b_flags &= ~B_DONE; 3340 } 3341 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 3342 BUF_ASSERT_HELD(bp); 3343 end: 3344 KASSERT(bp->b_bufobj == bo, 3345 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 3346 return (bp); 3347 } 3348 3349 /* 3350 * Get an empty, disassociated buffer of given size. The buffer is initially 3351 * set to B_INVAL. 3352 */ 3353 struct buf * 3354 geteblk(int size, int flags) 3355 { 3356 struct buf *bp; 3357 int maxsize; 3358 3359 maxsize = (size + BKVAMASK) & ~BKVAMASK; 3360 while ((bp = getnewbuf(NULL, 0, 0, size, maxsize, flags)) == NULL) { 3361 if ((flags & GB_NOWAIT_BD) && 3362 (curthread->td_pflags & TDP_BUFNEED) != 0) 3363 return (NULL); 3364 } 3365 allocbuf(bp, size); 3366 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 3367 BUF_ASSERT_HELD(bp); 3368 return (bp); 3369 } 3370 3371 3372 /* 3373 * This code constitutes the buffer memory from either anonymous system 3374 * memory (in the case of non-VMIO operations) or from an associated 3375 * VM object (in the case of VMIO operations). This code is able to 3376 * resize a buffer up or down. 3377 * 3378 * Note that this code is tricky, and has many complications to resolve 3379 * deadlock or inconsistant data situations. Tread lightly!!! 3380 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 3381 * the caller. Calling this code willy nilly can result in the loss of data. 3382 * 3383 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 3384 * B_CACHE for the non-VMIO case. 3385 */ 3386 3387 int 3388 allocbuf(struct buf *bp, int size) 3389 { 3390 int newbsize, mbsize; 3391 int i; 3392 3393 BUF_ASSERT_HELD(bp); 3394 3395 if (bp->b_kvasize < size) 3396 panic("allocbuf: buffer too small"); 3397 3398 if ((bp->b_flags & B_VMIO) == 0) { 3399 caddr_t origbuf; 3400 int origbufsize; 3401 /* 3402 * Just get anonymous memory from the kernel. Don't 3403 * mess with B_CACHE. 3404 */ 3405 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3406 if (bp->b_flags & B_MALLOC) 3407 newbsize = mbsize; 3408 else 3409 newbsize = round_page(size); 3410 3411 if (newbsize < bp->b_bufsize) { 3412 /* 3413 * malloced buffers are not shrunk 3414 */ 3415 if (bp->b_flags & B_MALLOC) { 3416 if (newbsize) { 3417 bp->b_bcount = size; 3418 } else { 3419 free(bp->b_data, M_BIOBUF); 3420 if (bp->b_bufsize) { 3421 atomic_subtract_long( 3422 &bufmallocspace, 3423 bp->b_bufsize); 3424 bufspacewakeup(); 3425 bp->b_bufsize = 0; 3426 } 3427 bp->b_saveaddr = bp->b_kvabase; 3428 bp->b_data = bp->b_saveaddr; 3429 bp->b_bcount = 0; 3430 bp->b_flags &= ~B_MALLOC; 3431 } 3432 return 1; 3433 } 3434 vm_hold_free_pages(bp, newbsize); 3435 } else if (newbsize > bp->b_bufsize) { 3436 /* 3437 * We only use malloced memory on the first allocation. 3438 * and revert to page-allocated memory when the buffer 3439 * grows. 3440 */ 3441 /* 3442 * There is a potential smp race here that could lead 3443 * to bufmallocspace slightly passing the max. It 3444 * is probably extremely rare and not worth worrying 3445 * over. 3446 */ 3447 if ( (bufmallocspace < maxbufmallocspace) && 3448 (bp->b_bufsize == 0) && 3449 (mbsize <= PAGE_SIZE/2)) { 3450 3451 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 3452 bp->b_bufsize = mbsize; 3453 bp->b_bcount = size; 3454 bp->b_flags |= B_MALLOC; 3455 atomic_add_long(&bufmallocspace, mbsize); 3456 return 1; 3457 } 3458 origbuf = NULL; 3459 origbufsize = 0; 3460 /* 3461 * If the buffer is growing on its other-than-first allocation, 3462 * then we revert to the page-allocation scheme. 3463 */ 3464 if (bp->b_flags & B_MALLOC) { 3465 origbuf = bp->b_data; 3466 origbufsize = bp->b_bufsize; 3467 bp->b_data = bp->b_kvabase; 3468 if (bp->b_bufsize) { 3469 atomic_subtract_long(&bufmallocspace, 3470 bp->b_bufsize); 3471 bufspacewakeup(); 3472 bp->b_bufsize = 0; 3473 } 3474 bp->b_flags &= ~B_MALLOC; 3475 newbsize = round_page(newbsize); 3476 } 3477 vm_hold_load_pages( 3478 bp, 3479 (vm_offset_t) bp->b_data + bp->b_bufsize, 3480 (vm_offset_t) bp->b_data + newbsize); 3481 if (origbuf) { 3482 bcopy(origbuf, bp->b_data, origbufsize); 3483 free(origbuf, M_BIOBUF); 3484 } 3485 } 3486 } else { 3487 int desiredpages; 3488 3489 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3490 desiredpages = (size == 0) ? 0 : 3491 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 3492 3493 if (bp->b_flags & B_MALLOC) 3494 panic("allocbuf: VMIO buffer can't be malloced"); 3495 /* 3496 * Set B_CACHE initially if buffer is 0 length or will become 3497 * 0-length. 3498 */ 3499 if (size == 0 || bp->b_bufsize == 0) 3500 bp->b_flags |= B_CACHE; 3501 3502 if (newbsize < bp->b_bufsize) { 3503 /* 3504 * DEV_BSIZE aligned new buffer size is less then the 3505 * DEV_BSIZE aligned existing buffer size. Figure out 3506 * if we have to remove any pages. 3507 */ 3508 if (desiredpages < bp->b_npages) { 3509 vm_page_t m; 3510 3511 if ((bp->b_flags & B_UNMAPPED) == 0) { 3512 BUF_CHECK_MAPPED(bp); 3513 pmap_qremove((vm_offset_t)trunc_page( 3514 (vm_offset_t)bp->b_data) + 3515 (desiredpages << PAGE_SHIFT), 3516 (bp->b_npages - desiredpages)); 3517 } else 3518 BUF_CHECK_UNMAPPED(bp); 3519 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 3520 for (i = desiredpages; i < bp->b_npages; i++) { 3521 /* 3522 * the page is not freed here -- it 3523 * is the responsibility of 3524 * vnode_pager_setsize 3525 */ 3526 m = bp->b_pages[i]; 3527 KASSERT(m != bogus_page, 3528 ("allocbuf: bogus page found")); 3529 while (vm_page_sleep_if_busy(m, 3530 "biodep")) 3531 continue; 3532 3533 bp->b_pages[i] = NULL; 3534 vm_page_lock(m); 3535 vm_page_unwire(m, PQ_INACTIVE); 3536 vm_page_unlock(m); 3537 } 3538 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 3539 bp->b_npages = desiredpages; 3540 } 3541 } else if (size > bp->b_bcount) { 3542 /* 3543 * We are growing the buffer, possibly in a 3544 * byte-granular fashion. 3545 */ 3546 vm_object_t obj; 3547 vm_offset_t toff; 3548 vm_offset_t tinc; 3549 3550 /* 3551 * Step 1, bring in the VM pages from the object, 3552 * allocating them if necessary. We must clear 3553 * B_CACHE if these pages are not valid for the 3554 * range covered by the buffer. 3555 */ 3556 3557 obj = bp->b_bufobj->bo_object; 3558 3559 VM_OBJECT_WLOCK(obj); 3560 while (bp->b_npages < desiredpages) { 3561 vm_page_t m; 3562 3563 /* 3564 * We must allocate system pages since blocking 3565 * here could interfere with paging I/O, no 3566 * matter which process we are. 3567 * 3568 * Only exclusive busy can be tested here. 3569 * Blocking on shared busy might lead to 3570 * deadlocks once allocbuf() is called after 3571 * pages are vfs_busy_pages(). 3572 */ 3573 m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) + 3574 bp->b_npages, VM_ALLOC_NOBUSY | 3575 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED | 3576 VM_ALLOC_IGN_SBUSY | 3577 VM_ALLOC_COUNT(desiredpages - bp->b_npages)); 3578 if (m->valid == 0) 3579 bp->b_flags &= ~B_CACHE; 3580 bp->b_pages[bp->b_npages] = m; 3581 ++bp->b_npages; 3582 } 3583 3584 /* 3585 * Step 2. We've loaded the pages into the buffer, 3586 * we have to figure out if we can still have B_CACHE 3587 * set. Note that B_CACHE is set according to the 3588 * byte-granular range ( bcount and size ), new the 3589 * aligned range ( newbsize ). 3590 * 3591 * The VM test is against m->valid, which is DEV_BSIZE 3592 * aligned. Needless to say, the validity of the data 3593 * needs to also be DEV_BSIZE aligned. Note that this 3594 * fails with NFS if the server or some other client 3595 * extends the file's EOF. If our buffer is resized, 3596 * B_CACHE may remain set! XXX 3597 */ 3598 3599 toff = bp->b_bcount; 3600 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 3601 3602 while ((bp->b_flags & B_CACHE) && toff < size) { 3603 vm_pindex_t pi; 3604 3605 if (tinc > (size - toff)) 3606 tinc = size - toff; 3607 3608 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 3609 PAGE_SHIFT; 3610 3611 vfs_buf_test_cache( 3612 bp, 3613 bp->b_offset, 3614 toff, 3615 tinc, 3616 bp->b_pages[pi] 3617 ); 3618 toff += tinc; 3619 tinc = PAGE_SIZE; 3620 } 3621 VM_OBJECT_WUNLOCK(obj); 3622 3623 /* 3624 * Step 3, fixup the KVM pmap. 3625 */ 3626 if ((bp->b_flags & B_UNMAPPED) == 0) 3627 bpmap_qenter(bp); 3628 else 3629 BUF_CHECK_UNMAPPED(bp); 3630 } 3631 } 3632 if (newbsize < bp->b_bufsize) 3633 bufspacewakeup(); 3634 bp->b_bufsize = newbsize; /* actual buffer allocation */ 3635 bp->b_bcount = size; /* requested buffer size */ 3636 return 1; 3637 } 3638 3639 extern int inflight_transient_maps; 3640 3641 void 3642 biodone(struct bio *bp) 3643 { 3644 struct mtx *mtxp; 3645 void (*done)(struct bio *); 3646 vm_offset_t start, end; 3647 3648 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) { 3649 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING; 3650 bp->bio_flags |= BIO_UNMAPPED; 3651 start = trunc_page((vm_offset_t)bp->bio_data); 3652 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length); 3653 bp->bio_data = unmapped_buf; 3654 pmap_qremove(start, OFF_TO_IDX(end - start)); 3655 vmem_free(transient_arena, start, end - start); 3656 atomic_add_int(&inflight_transient_maps, -1); 3657 } 3658 done = bp->bio_done; 3659 if (done == NULL) { 3660 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3661 mtx_lock(mtxp); 3662 bp->bio_flags |= BIO_DONE; 3663 wakeup(bp); 3664 mtx_unlock(mtxp); 3665 } else { 3666 bp->bio_flags |= BIO_DONE; 3667 done(bp); 3668 } 3669 } 3670 3671 /* 3672 * Wait for a BIO to finish. 3673 */ 3674 int 3675 biowait(struct bio *bp, const char *wchan) 3676 { 3677 struct mtx *mtxp; 3678 3679 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3680 mtx_lock(mtxp); 3681 while ((bp->bio_flags & BIO_DONE) == 0) 3682 msleep(bp, mtxp, PRIBIO, wchan, 0); 3683 mtx_unlock(mtxp); 3684 if (bp->bio_error != 0) 3685 return (bp->bio_error); 3686 if (!(bp->bio_flags & BIO_ERROR)) 3687 return (0); 3688 return (EIO); 3689 } 3690 3691 void 3692 biofinish(struct bio *bp, struct devstat *stat, int error) 3693 { 3694 3695 if (error) { 3696 bp->bio_error = error; 3697 bp->bio_flags |= BIO_ERROR; 3698 } 3699 if (stat != NULL) 3700 devstat_end_transaction_bio(stat, bp); 3701 biodone(bp); 3702 } 3703 3704 /* 3705 * bufwait: 3706 * 3707 * Wait for buffer I/O completion, returning error status. The buffer 3708 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3709 * error and cleared. 3710 */ 3711 int 3712 bufwait(struct buf *bp) 3713 { 3714 if (bp->b_iocmd == BIO_READ) 3715 bwait(bp, PRIBIO, "biord"); 3716 else 3717 bwait(bp, PRIBIO, "biowr"); 3718 if (bp->b_flags & B_EINTR) { 3719 bp->b_flags &= ~B_EINTR; 3720 return (EINTR); 3721 } 3722 if (bp->b_ioflags & BIO_ERROR) { 3723 return (bp->b_error ? bp->b_error : EIO); 3724 } else { 3725 return (0); 3726 } 3727 } 3728 3729 /* 3730 * Call back function from struct bio back up to struct buf. 3731 */ 3732 static void 3733 bufdonebio(struct bio *bip) 3734 { 3735 struct buf *bp; 3736 3737 bp = bip->bio_caller2; 3738 bp->b_resid = bip->bio_resid; 3739 bp->b_ioflags = bip->bio_flags; 3740 bp->b_error = bip->bio_error; 3741 if (bp->b_error) 3742 bp->b_ioflags |= BIO_ERROR; 3743 bufdone(bp); 3744 g_destroy_bio(bip); 3745 } 3746 3747 void 3748 dev_strategy(struct cdev *dev, struct buf *bp) 3749 { 3750 struct cdevsw *csw; 3751 int ref; 3752 3753 KASSERT(dev->si_refcount > 0, 3754 ("dev_strategy on un-referenced struct cdev *(%s) %p", 3755 devtoname(dev), dev)); 3756 3757 csw = dev_refthread(dev, &ref); 3758 dev_strategy_csw(dev, csw, bp); 3759 dev_relthread(dev, ref); 3760 } 3761 3762 void 3763 dev_strategy_csw(struct cdev *dev, struct cdevsw *csw, struct buf *bp) 3764 { 3765 struct bio *bip; 3766 3767 KASSERT(bp->b_iocmd == BIO_READ || bp->b_iocmd == BIO_WRITE, 3768 ("b_iocmd botch")); 3769 KASSERT(((dev->si_flags & SI_ETERNAL) != 0 && csw != NULL) || 3770 dev->si_threadcount > 0, 3771 ("dev_strategy_csw threadcount cdev *(%s) %p", devtoname(dev), 3772 dev)); 3773 if (csw == NULL) { 3774 bp->b_error = ENXIO; 3775 bp->b_ioflags = BIO_ERROR; 3776 bufdone(bp); 3777 return; 3778 } 3779 for (;;) { 3780 bip = g_new_bio(); 3781 if (bip != NULL) 3782 break; 3783 /* Try again later */ 3784 tsleep(&bp, PRIBIO, "dev_strat", hz/10); 3785 } 3786 bip->bio_cmd = bp->b_iocmd; 3787 bip->bio_offset = bp->b_iooffset; 3788 bip->bio_length = bp->b_bcount; 3789 bip->bio_bcount = bp->b_bcount; /* XXX: remove */ 3790 bdata2bio(bp, bip); 3791 bip->bio_done = bufdonebio; 3792 bip->bio_caller2 = bp; 3793 bip->bio_dev = dev; 3794 (*csw->d_strategy)(bip); 3795 } 3796 3797 /* 3798 * bufdone: 3799 * 3800 * Finish I/O on a buffer, optionally calling a completion function. 3801 * This is usually called from an interrupt so process blocking is 3802 * not allowed. 3803 * 3804 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3805 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3806 * assuming B_INVAL is clear. 3807 * 3808 * For the VMIO case, we set B_CACHE if the op was a read and no 3809 * read error occured, or if the op was a write. B_CACHE is never 3810 * set if the buffer is invalid or otherwise uncacheable. 3811 * 3812 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3813 * initiator to leave B_INVAL set to brelse the buffer out of existance 3814 * in the biodone routine. 3815 */ 3816 void 3817 bufdone(struct buf *bp) 3818 { 3819 struct bufobj *dropobj; 3820 void (*biodone)(struct buf *); 3821 3822 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 3823 dropobj = NULL; 3824 3825 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 3826 BUF_ASSERT_HELD(bp); 3827 3828 runningbufwakeup(bp); 3829 if (bp->b_iocmd == BIO_WRITE) 3830 dropobj = bp->b_bufobj; 3831 /* call optional completion function if requested */ 3832 if (bp->b_iodone != NULL) { 3833 biodone = bp->b_iodone; 3834 bp->b_iodone = NULL; 3835 (*biodone) (bp); 3836 if (dropobj) 3837 bufobj_wdrop(dropobj); 3838 return; 3839 } 3840 3841 bufdone_finish(bp); 3842 3843 if (dropobj) 3844 bufobj_wdrop(dropobj); 3845 } 3846 3847 void 3848 bufdone_finish(struct buf *bp) 3849 { 3850 BUF_ASSERT_HELD(bp); 3851 3852 if (!LIST_EMPTY(&bp->b_dep)) 3853 buf_complete(bp); 3854 3855 if (bp->b_flags & B_VMIO) { 3856 vm_ooffset_t foff; 3857 vm_page_t m; 3858 vm_object_t obj; 3859 struct vnode *vp; 3860 int bogus, i, iosize; 3861 3862 obj = bp->b_bufobj->bo_object; 3863 KASSERT(obj->paging_in_progress >= bp->b_npages, 3864 ("biodone_finish: paging in progress(%d) < b_npages(%d)", 3865 obj->paging_in_progress, bp->b_npages)); 3866 3867 vp = bp->b_vp; 3868 KASSERT(vp->v_holdcnt > 0, 3869 ("biodone_finish: vnode %p has zero hold count", vp)); 3870 KASSERT(vp->v_object != NULL, 3871 ("biodone_finish: vnode %p has no vm_object", vp)); 3872 3873 foff = bp->b_offset; 3874 KASSERT(bp->b_offset != NOOFFSET, 3875 ("biodone_finish: bp %p has no buffer offset", bp)); 3876 3877 /* 3878 * Set B_CACHE if the op was a normal read and no error 3879 * occured. B_CACHE is set for writes in the b*write() 3880 * routines. 3881 */ 3882 iosize = bp->b_bcount - bp->b_resid; 3883 if (bp->b_iocmd == BIO_READ && 3884 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 3885 !(bp->b_ioflags & BIO_ERROR)) { 3886 bp->b_flags |= B_CACHE; 3887 } 3888 bogus = 0; 3889 VM_OBJECT_WLOCK(obj); 3890 for (i = 0; i < bp->b_npages; i++) { 3891 int bogusflag = 0; 3892 int resid; 3893 3894 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 3895 if (resid > iosize) 3896 resid = iosize; 3897 3898 /* 3899 * cleanup bogus pages, restoring the originals 3900 */ 3901 m = bp->b_pages[i]; 3902 if (m == bogus_page) { 3903 bogus = bogusflag = 1; 3904 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3905 if (m == NULL) 3906 panic("biodone: page disappeared!"); 3907 bp->b_pages[i] = m; 3908 } 3909 KASSERT(OFF_TO_IDX(foff) == m->pindex, 3910 ("biodone_finish: foff(%jd)/pindex(%ju) mismatch", 3911 (intmax_t)foff, (uintmax_t)m->pindex)); 3912 3913 /* 3914 * In the write case, the valid and clean bits are 3915 * already changed correctly ( see bdwrite() ), so we 3916 * only need to do this here in the read case. 3917 */ 3918 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 3919 KASSERT((m->dirty & vm_page_bits(foff & 3920 PAGE_MASK, resid)) == 0, ("bufdone_finish:" 3921 " page %p has unexpected dirty bits", m)); 3922 vfs_page_set_valid(bp, foff, m); 3923 } 3924 3925 vm_page_sunbusy(m); 3926 vm_object_pip_subtract(obj, 1); 3927 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3928 iosize -= resid; 3929 } 3930 vm_object_pip_wakeupn(obj, 0); 3931 VM_OBJECT_WUNLOCK(obj); 3932 if (bogus && (bp->b_flags & B_UNMAPPED) == 0) { 3933 BUF_CHECK_MAPPED(bp); 3934 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3935 bp->b_pages, bp->b_npages); 3936 } 3937 } 3938 3939 /* 3940 * For asynchronous completions, release the buffer now. The brelse 3941 * will do a wakeup there if necessary - so no need to do a wakeup 3942 * here in the async case. The sync case always needs to do a wakeup. 3943 */ 3944 3945 if (bp->b_flags & B_ASYNC) { 3946 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 3947 brelse(bp); 3948 else 3949 bqrelse(bp); 3950 } else 3951 bdone(bp); 3952 } 3953 3954 /* 3955 * This routine is called in lieu of iodone in the case of 3956 * incomplete I/O. This keeps the busy status for pages 3957 * consistant. 3958 */ 3959 void 3960 vfs_unbusy_pages(struct buf *bp) 3961 { 3962 int i; 3963 vm_object_t obj; 3964 vm_page_t m; 3965 3966 runningbufwakeup(bp); 3967 if (!(bp->b_flags & B_VMIO)) 3968 return; 3969 3970 obj = bp->b_bufobj->bo_object; 3971 VM_OBJECT_WLOCK(obj); 3972 for (i = 0; i < bp->b_npages; i++) { 3973 m = bp->b_pages[i]; 3974 if (m == bogus_page) { 3975 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 3976 if (!m) 3977 panic("vfs_unbusy_pages: page missing\n"); 3978 bp->b_pages[i] = m; 3979 if ((bp->b_flags & B_UNMAPPED) == 0) { 3980 BUF_CHECK_MAPPED(bp); 3981 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3982 bp->b_pages, bp->b_npages); 3983 } else 3984 BUF_CHECK_UNMAPPED(bp); 3985 } 3986 vm_object_pip_subtract(obj, 1); 3987 vm_page_sunbusy(m); 3988 } 3989 vm_object_pip_wakeupn(obj, 0); 3990 VM_OBJECT_WUNLOCK(obj); 3991 } 3992 3993 /* 3994 * vfs_page_set_valid: 3995 * 3996 * Set the valid bits in a page based on the supplied offset. The 3997 * range is restricted to the buffer's size. 3998 * 3999 * This routine is typically called after a read completes. 4000 */ 4001 static void 4002 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4003 { 4004 vm_ooffset_t eoff; 4005 4006 /* 4007 * Compute the end offset, eoff, such that [off, eoff) does not span a 4008 * page boundary and eoff is not greater than the end of the buffer. 4009 * The end of the buffer, in this case, is our file EOF, not the 4010 * allocation size of the buffer. 4011 */ 4012 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 4013 if (eoff > bp->b_offset + bp->b_bcount) 4014 eoff = bp->b_offset + bp->b_bcount; 4015 4016 /* 4017 * Set valid range. This is typically the entire buffer and thus the 4018 * entire page. 4019 */ 4020 if (eoff > off) 4021 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off); 4022 } 4023 4024 /* 4025 * vfs_page_set_validclean: 4026 * 4027 * Set the valid bits and clear the dirty bits in a page based on the 4028 * supplied offset. The range is restricted to the buffer's size. 4029 */ 4030 static void 4031 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4032 { 4033 vm_ooffset_t soff, eoff; 4034 4035 /* 4036 * Start and end offsets in buffer. eoff - soff may not cross a 4037 * page boundry or cross the end of the buffer. The end of the 4038 * buffer, in this case, is our file EOF, not the allocation size 4039 * of the buffer. 4040 */ 4041 soff = off; 4042 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4043 if (eoff > bp->b_offset + bp->b_bcount) 4044 eoff = bp->b_offset + bp->b_bcount; 4045 4046 /* 4047 * Set valid range. This is typically the entire buffer and thus the 4048 * entire page. 4049 */ 4050 if (eoff > soff) { 4051 vm_page_set_validclean( 4052 m, 4053 (vm_offset_t) (soff & PAGE_MASK), 4054 (vm_offset_t) (eoff - soff) 4055 ); 4056 } 4057 } 4058 4059 /* 4060 * Ensure that all buffer pages are not exclusive busied. If any page is 4061 * exclusive busy, drain it. 4062 */ 4063 void 4064 vfs_drain_busy_pages(struct buf *bp) 4065 { 4066 vm_page_t m; 4067 int i, last_busied; 4068 4069 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object); 4070 last_busied = 0; 4071 for (i = 0; i < bp->b_npages; i++) { 4072 m = bp->b_pages[i]; 4073 if (vm_page_xbusied(m)) { 4074 for (; last_busied < i; last_busied++) 4075 vm_page_sbusy(bp->b_pages[last_busied]); 4076 while (vm_page_xbusied(m)) { 4077 vm_page_lock(m); 4078 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4079 vm_page_busy_sleep(m, "vbpage"); 4080 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4081 } 4082 } 4083 } 4084 for (i = 0; i < last_busied; i++) 4085 vm_page_sunbusy(bp->b_pages[i]); 4086 } 4087 4088 /* 4089 * This routine is called before a device strategy routine. 4090 * It is used to tell the VM system that paging I/O is in 4091 * progress, and treat the pages associated with the buffer 4092 * almost as being exclusive busy. Also the object paging_in_progress 4093 * flag is handled to make sure that the object doesn't become 4094 * inconsistant. 4095 * 4096 * Since I/O has not been initiated yet, certain buffer flags 4097 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 4098 * and should be ignored. 4099 */ 4100 void 4101 vfs_busy_pages(struct buf *bp, int clear_modify) 4102 { 4103 int i, bogus; 4104 vm_object_t obj; 4105 vm_ooffset_t foff; 4106 vm_page_t m; 4107 4108 if (!(bp->b_flags & B_VMIO)) 4109 return; 4110 4111 obj = bp->b_bufobj->bo_object; 4112 foff = bp->b_offset; 4113 KASSERT(bp->b_offset != NOOFFSET, 4114 ("vfs_busy_pages: no buffer offset")); 4115 VM_OBJECT_WLOCK(obj); 4116 vfs_drain_busy_pages(bp); 4117 if (bp->b_bufsize != 0) 4118 vfs_setdirty_locked_object(bp); 4119 bogus = 0; 4120 for (i = 0; i < bp->b_npages; i++) { 4121 m = bp->b_pages[i]; 4122 4123 if ((bp->b_flags & B_CLUSTER) == 0) { 4124 vm_object_pip_add(obj, 1); 4125 vm_page_sbusy(m); 4126 } 4127 /* 4128 * When readying a buffer for a read ( i.e 4129 * clear_modify == 0 ), it is important to do 4130 * bogus_page replacement for valid pages in 4131 * partially instantiated buffers. Partially 4132 * instantiated buffers can, in turn, occur when 4133 * reconstituting a buffer from its VM backing store 4134 * base. We only have to do this if B_CACHE is 4135 * clear ( which causes the I/O to occur in the 4136 * first place ). The replacement prevents the read 4137 * I/O from overwriting potentially dirty VM-backed 4138 * pages. XXX bogus page replacement is, uh, bogus. 4139 * It may not work properly with small-block devices. 4140 * We need to find a better way. 4141 */ 4142 if (clear_modify) { 4143 pmap_remove_write(m); 4144 vfs_page_set_validclean(bp, foff, m); 4145 } else if (m->valid == VM_PAGE_BITS_ALL && 4146 (bp->b_flags & B_CACHE) == 0) { 4147 bp->b_pages[i] = bogus_page; 4148 bogus++; 4149 } 4150 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4151 } 4152 VM_OBJECT_WUNLOCK(obj); 4153 if (bogus && (bp->b_flags & B_UNMAPPED) == 0) { 4154 BUF_CHECK_MAPPED(bp); 4155 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4156 bp->b_pages, bp->b_npages); 4157 } 4158 } 4159 4160 /* 4161 * vfs_bio_set_valid: 4162 * 4163 * Set the range within the buffer to valid. The range is 4164 * relative to the beginning of the buffer, b_offset. Note that 4165 * b_offset itself may be offset from the beginning of the first 4166 * page. 4167 */ 4168 void 4169 vfs_bio_set_valid(struct buf *bp, int base, int size) 4170 { 4171 int i, n; 4172 vm_page_t m; 4173 4174 if (!(bp->b_flags & B_VMIO)) 4175 return; 4176 4177 /* 4178 * Fixup base to be relative to beginning of first page. 4179 * Set initial n to be the maximum number of bytes in the 4180 * first page that can be validated. 4181 */ 4182 base += (bp->b_offset & PAGE_MASK); 4183 n = PAGE_SIZE - (base & PAGE_MASK); 4184 4185 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4186 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4187 m = bp->b_pages[i]; 4188 if (n > size) 4189 n = size; 4190 vm_page_set_valid_range(m, base & PAGE_MASK, n); 4191 base += n; 4192 size -= n; 4193 n = PAGE_SIZE; 4194 } 4195 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4196 } 4197 4198 /* 4199 * vfs_bio_clrbuf: 4200 * 4201 * If the specified buffer is a non-VMIO buffer, clear the entire 4202 * buffer. If the specified buffer is a VMIO buffer, clear and 4203 * validate only the previously invalid portions of the buffer. 4204 * This routine essentially fakes an I/O, so we need to clear 4205 * BIO_ERROR and B_INVAL. 4206 * 4207 * Note that while we only theoretically need to clear through b_bcount, 4208 * we go ahead and clear through b_bufsize. 4209 */ 4210 void 4211 vfs_bio_clrbuf(struct buf *bp) 4212 { 4213 int i, j, mask, sa, ea, slide; 4214 4215 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 4216 clrbuf(bp); 4217 return; 4218 } 4219 bp->b_flags &= ~B_INVAL; 4220 bp->b_ioflags &= ~BIO_ERROR; 4221 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4222 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 4223 (bp->b_offset & PAGE_MASK) == 0) { 4224 if (bp->b_pages[0] == bogus_page) 4225 goto unlock; 4226 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 4227 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object); 4228 if ((bp->b_pages[0]->valid & mask) == mask) 4229 goto unlock; 4230 if ((bp->b_pages[0]->valid & mask) == 0) { 4231 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize); 4232 bp->b_pages[0]->valid |= mask; 4233 goto unlock; 4234 } 4235 } 4236 sa = bp->b_offset & PAGE_MASK; 4237 slide = 0; 4238 for (i = 0; i < bp->b_npages; i++, sa = 0) { 4239 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize); 4240 ea = slide & PAGE_MASK; 4241 if (ea == 0) 4242 ea = PAGE_SIZE; 4243 if (bp->b_pages[i] == bogus_page) 4244 continue; 4245 j = sa / DEV_BSIZE; 4246 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 4247 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object); 4248 if ((bp->b_pages[i]->valid & mask) == mask) 4249 continue; 4250 if ((bp->b_pages[i]->valid & mask) == 0) 4251 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa); 4252 else { 4253 for (; sa < ea; sa += DEV_BSIZE, j++) { 4254 if ((bp->b_pages[i]->valid & (1 << j)) == 0) { 4255 pmap_zero_page_area(bp->b_pages[i], 4256 sa, DEV_BSIZE); 4257 } 4258 } 4259 } 4260 bp->b_pages[i]->valid |= mask; 4261 } 4262 unlock: 4263 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4264 bp->b_resid = 0; 4265 } 4266 4267 void 4268 vfs_bio_bzero_buf(struct buf *bp, int base, int size) 4269 { 4270 vm_page_t m; 4271 int i, n; 4272 4273 if ((bp->b_flags & B_UNMAPPED) == 0) { 4274 BUF_CHECK_MAPPED(bp); 4275 bzero(bp->b_data + base, size); 4276 } else { 4277 BUF_CHECK_UNMAPPED(bp); 4278 n = PAGE_SIZE - (base & PAGE_MASK); 4279 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4280 m = bp->b_pages[i]; 4281 if (n > size) 4282 n = size; 4283 pmap_zero_page_area(m, base & PAGE_MASK, n); 4284 base += n; 4285 size -= n; 4286 n = PAGE_SIZE; 4287 } 4288 } 4289 } 4290 4291 /* 4292 * vm_hold_load_pages and vm_hold_free_pages get pages into 4293 * a buffers address space. The pages are anonymous and are 4294 * not associated with a file object. 4295 */ 4296 static void 4297 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4298 { 4299 vm_offset_t pg; 4300 vm_page_t p; 4301 int index; 4302 4303 BUF_CHECK_MAPPED(bp); 4304 4305 to = round_page(to); 4306 from = round_page(from); 4307 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4308 4309 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 4310 tryagain: 4311 /* 4312 * note: must allocate system pages since blocking here 4313 * could interfere with paging I/O, no matter which 4314 * process we are. 4315 */ 4316 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ | 4317 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT)); 4318 if (p == NULL) { 4319 VM_WAIT; 4320 goto tryagain; 4321 } 4322 pmap_qenter(pg, &p, 1); 4323 bp->b_pages[index] = p; 4324 } 4325 bp->b_npages = index; 4326 } 4327 4328 /* Return pages associated with this buf to the vm system */ 4329 static void 4330 vm_hold_free_pages(struct buf *bp, int newbsize) 4331 { 4332 vm_offset_t from; 4333 vm_page_t p; 4334 int index, newnpages; 4335 4336 BUF_CHECK_MAPPED(bp); 4337 4338 from = round_page((vm_offset_t)bp->b_data + newbsize); 4339 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4340 if (bp->b_npages > newnpages) 4341 pmap_qremove(from, bp->b_npages - newnpages); 4342 for (index = newnpages; index < bp->b_npages; index++) { 4343 p = bp->b_pages[index]; 4344 bp->b_pages[index] = NULL; 4345 if (vm_page_sbusied(p)) 4346 printf("vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 4347 (intmax_t)bp->b_blkno, (intmax_t)bp->b_lblkno); 4348 p->wire_count--; 4349 vm_page_free(p); 4350 atomic_subtract_int(&vm_cnt.v_wire_count, 1); 4351 } 4352 bp->b_npages = newnpages; 4353 } 4354 4355 /* 4356 * Map an IO request into kernel virtual address space. 4357 * 4358 * All requests are (re)mapped into kernel VA space. 4359 * Notice that we use b_bufsize for the size of the buffer 4360 * to be mapped. b_bcount might be modified by the driver. 4361 * 4362 * Note that even if the caller determines that the address space should 4363 * be valid, a race or a smaller-file mapped into a larger space may 4364 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 4365 * check the return value. 4366 */ 4367 int 4368 vmapbuf(struct buf *bp, int mapbuf) 4369 { 4370 caddr_t kva; 4371 vm_prot_t prot; 4372 int pidx; 4373 4374 if (bp->b_bufsize < 0) 4375 return (-1); 4376 prot = VM_PROT_READ; 4377 if (bp->b_iocmd == BIO_READ) 4378 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 4379 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 4380 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages, 4381 btoc(MAXPHYS))) < 0) 4382 return (-1); 4383 bp->b_npages = pidx; 4384 if (mapbuf || !unmapped_buf_allowed) { 4385 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx); 4386 kva = bp->b_saveaddr; 4387 bp->b_saveaddr = bp->b_data; 4388 bp->b_data = kva + (((vm_offset_t)bp->b_data) & PAGE_MASK); 4389 bp->b_flags &= ~B_UNMAPPED; 4390 } else { 4391 bp->b_flags |= B_UNMAPPED; 4392 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK; 4393 bp->b_saveaddr = bp->b_data; 4394 bp->b_data = unmapped_buf; 4395 } 4396 return(0); 4397 } 4398 4399 /* 4400 * Free the io map PTEs associated with this IO operation. 4401 * We also invalidate the TLB entries and restore the original b_addr. 4402 */ 4403 void 4404 vunmapbuf(struct buf *bp) 4405 { 4406 int npages; 4407 4408 npages = bp->b_npages; 4409 if (bp->b_flags & B_UNMAPPED) 4410 bp->b_flags &= ~B_UNMAPPED; 4411 else 4412 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 4413 vm_page_unhold_pages(bp->b_pages, npages); 4414 4415 bp->b_data = bp->b_saveaddr; 4416 } 4417 4418 void 4419 bdone(struct buf *bp) 4420 { 4421 struct mtx *mtxp; 4422 4423 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4424 mtx_lock(mtxp); 4425 bp->b_flags |= B_DONE; 4426 wakeup(bp); 4427 mtx_unlock(mtxp); 4428 } 4429 4430 void 4431 bwait(struct buf *bp, u_char pri, const char *wchan) 4432 { 4433 struct mtx *mtxp; 4434 4435 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4436 mtx_lock(mtxp); 4437 while ((bp->b_flags & B_DONE) == 0) 4438 msleep(bp, mtxp, pri, wchan, 0); 4439 mtx_unlock(mtxp); 4440 } 4441 4442 int 4443 bufsync(struct bufobj *bo, int waitfor) 4444 { 4445 4446 return (VOP_FSYNC(bo->__bo_vnode, waitfor, curthread)); 4447 } 4448 4449 void 4450 bufstrategy(struct bufobj *bo, struct buf *bp) 4451 { 4452 int i = 0; 4453 struct vnode *vp; 4454 4455 vp = bp->b_vp; 4456 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 4457 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 4458 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 4459 i = VOP_STRATEGY(vp, bp); 4460 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 4461 } 4462 4463 void 4464 bufobj_wrefl(struct bufobj *bo) 4465 { 4466 4467 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4468 ASSERT_BO_WLOCKED(bo); 4469 bo->bo_numoutput++; 4470 } 4471 4472 void 4473 bufobj_wref(struct bufobj *bo) 4474 { 4475 4476 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4477 BO_LOCK(bo); 4478 bo->bo_numoutput++; 4479 BO_UNLOCK(bo); 4480 } 4481 4482 void 4483 bufobj_wdrop(struct bufobj *bo) 4484 { 4485 4486 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 4487 BO_LOCK(bo); 4488 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 4489 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 4490 bo->bo_flag &= ~BO_WWAIT; 4491 wakeup(&bo->bo_numoutput); 4492 } 4493 BO_UNLOCK(bo); 4494 } 4495 4496 int 4497 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 4498 { 4499 int error; 4500 4501 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 4502 ASSERT_BO_WLOCKED(bo); 4503 error = 0; 4504 while (bo->bo_numoutput) { 4505 bo->bo_flag |= BO_WWAIT; 4506 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo), 4507 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 4508 if (error) 4509 break; 4510 } 4511 return (error); 4512 } 4513 4514 void 4515 bpin(struct buf *bp) 4516 { 4517 struct mtx *mtxp; 4518 4519 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4520 mtx_lock(mtxp); 4521 bp->b_pin_count++; 4522 mtx_unlock(mtxp); 4523 } 4524 4525 void 4526 bunpin(struct buf *bp) 4527 { 4528 struct mtx *mtxp; 4529 4530 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4531 mtx_lock(mtxp); 4532 if (--bp->b_pin_count == 0) 4533 wakeup(bp); 4534 mtx_unlock(mtxp); 4535 } 4536 4537 void 4538 bunpin_wait(struct buf *bp) 4539 { 4540 struct mtx *mtxp; 4541 4542 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4543 mtx_lock(mtxp); 4544 while (bp->b_pin_count > 0) 4545 msleep(bp, mtxp, PRIBIO, "bwunpin", 0); 4546 mtx_unlock(mtxp); 4547 } 4548 4549 /* 4550 * Set bio_data or bio_ma for struct bio from the struct buf. 4551 */ 4552 void 4553 bdata2bio(struct buf *bp, struct bio *bip) 4554 { 4555 4556 if ((bp->b_flags & B_UNMAPPED) != 0) { 4557 KASSERT(unmapped_buf_allowed, ("unmapped")); 4558 bip->bio_ma = bp->b_pages; 4559 bip->bio_ma_n = bp->b_npages; 4560 bip->bio_data = unmapped_buf; 4561 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 4562 bip->bio_flags |= BIO_UNMAPPED; 4563 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) / 4564 PAGE_SIZE == bp->b_npages, 4565 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset, 4566 (long long)bip->bio_length, bip->bio_ma_n)); 4567 } else { 4568 bip->bio_data = bp->b_data; 4569 bip->bio_ma = NULL; 4570 } 4571 } 4572 4573 #include "opt_ddb.h" 4574 #ifdef DDB 4575 #include <ddb/ddb.h> 4576 4577 /* DDB command to show buffer data */ 4578 DB_SHOW_COMMAND(buffer, db_show_buffer) 4579 { 4580 /* get args */ 4581 struct buf *bp = (struct buf *)addr; 4582 4583 if (!have_addr) { 4584 db_printf("usage: show buffer <addr>\n"); 4585 return; 4586 } 4587 4588 db_printf("buf at %p\n", bp); 4589 db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n", 4590 (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags, 4591 PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS); 4592 db_printf( 4593 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 4594 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, " 4595 "b_dep = %p\n", 4596 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 4597 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 4598 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first); 4599 if (bp->b_npages) { 4600 int i; 4601 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 4602 for (i = 0; i < bp->b_npages; i++) { 4603 vm_page_t m; 4604 m = bp->b_pages[i]; 4605 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 4606 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 4607 if ((i + 1) < bp->b_npages) 4608 db_printf(","); 4609 } 4610 db_printf("\n"); 4611 } 4612 db_printf(" "); 4613 BUF_LOCKPRINTINFO(bp); 4614 } 4615 4616 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 4617 { 4618 struct buf *bp; 4619 int i; 4620 4621 for (i = 0; i < nbuf; i++) { 4622 bp = &buf[i]; 4623 if (BUF_ISLOCKED(bp)) { 4624 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4625 db_printf("\n"); 4626 } 4627 } 4628 } 4629 4630 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 4631 { 4632 struct vnode *vp; 4633 struct buf *bp; 4634 4635 if (!have_addr) { 4636 db_printf("usage: show vnodebufs <addr>\n"); 4637 return; 4638 } 4639 vp = (struct vnode *)addr; 4640 db_printf("Clean buffers:\n"); 4641 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 4642 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4643 db_printf("\n"); 4644 } 4645 db_printf("Dirty buffers:\n"); 4646 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 4647 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4648 db_printf("\n"); 4649 } 4650 } 4651 4652 DB_COMMAND(countfreebufs, db_coundfreebufs) 4653 { 4654 struct buf *bp; 4655 int i, used = 0, nfree = 0; 4656 4657 if (have_addr) { 4658 db_printf("usage: countfreebufs\n"); 4659 return; 4660 } 4661 4662 for (i = 0; i < nbuf; i++) { 4663 bp = &buf[i]; 4664 if ((bp->b_flags & B_INFREECNT) != 0) 4665 nfree++; 4666 else 4667 used++; 4668 } 4669 4670 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 4671 nfree + used); 4672 db_printf("numfreebuffers is %d\n", numfreebuffers); 4673 } 4674 #endif /* DDB */ 4675