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