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