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 if (bp->b_runningbufspace == 0) 478 return; 479 space = atomic_fetchadd_long(&runningbufspace, -bp->b_runningbufspace); 480 bspace = bp->b_runningbufspace; 481 bp->b_runningbufspace = 0; 482 /* 483 * Only acquire the lock and wakeup on the transition from exceeding 484 * the threshold to falling below it. 485 */ 486 if (space < lorunningspace) 487 return; 488 if (space - bspace > lorunningspace) 489 return; 490 runningwakeup(); 491 } 492 493 /* 494 * bufcountadd: 495 * 496 * Called when a buffer has been added to one of the free queues to 497 * account for the buffer and to wakeup anyone waiting for free buffers. 498 * This typically occurs when large amounts of metadata are being handled 499 * by the buffer cache ( else buffer space runs out first, usually ). 500 */ 501 static __inline void 502 bufcountadd(struct buf *bp) 503 { 504 int old; 505 506 KASSERT((bp->b_flags & B_INFREECNT) == 0, 507 ("buf %p already counted as free", bp)); 508 bp->b_flags |= B_INFREECNT; 509 old = atomic_fetchadd_int(&numfreebuffers, 1); 510 KASSERT(old >= 0 && old < nbuf, 511 ("numfreebuffers climbed to %d", old + 1)); 512 mtx_lock(&nblock); 513 if (needsbuffer) { 514 needsbuffer &= ~VFS_BIO_NEED_ANY; 515 if (numfreebuffers >= hifreebuffers) 516 needsbuffer &= ~VFS_BIO_NEED_FREE; 517 wakeup(&needsbuffer); 518 } 519 mtx_unlock(&nblock); 520 } 521 522 /* 523 * bufcountsub: 524 * 525 * Decrement the numfreebuffers count as needed. 526 */ 527 static void 528 bufcountsub(struct buf *bp) 529 { 530 int old; 531 532 /* 533 * Fixup numfreebuffers count. If the buffer is invalid or not 534 * delayed-write, the buffer was free and we must decrement 535 * numfreebuffers. 536 */ 537 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { 538 KASSERT((bp->b_flags & B_INFREECNT) != 0, 539 ("buf %p not counted in numfreebuffers", bp)); 540 bp->b_flags &= ~B_INFREECNT; 541 old = atomic_fetchadd_int(&numfreebuffers, -1); 542 KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1)); 543 } 544 } 545 546 /* 547 * waitrunningbufspace() 548 * 549 * runningbufspace is a measure of the amount of I/O currently 550 * running. This routine is used in async-write situations to 551 * prevent creating huge backups of pending writes to a device. 552 * Only asynchronous writes are governed by this function. 553 * 554 * This does NOT turn an async write into a sync write. It waits 555 * for earlier writes to complete and generally returns before the 556 * caller's write has reached the device. 557 */ 558 void 559 waitrunningbufspace(void) 560 { 561 562 mtx_lock(&rbreqlock); 563 while (runningbufspace > hirunningspace) { 564 ++runningbufreq; 565 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 566 } 567 mtx_unlock(&rbreqlock); 568 } 569 570 571 /* 572 * vfs_buf_test_cache: 573 * 574 * Called when a buffer is extended. This function clears the B_CACHE 575 * bit if the newly extended portion of the buffer does not contain 576 * valid data. 577 */ 578 static __inline 579 void 580 vfs_buf_test_cache(struct buf *bp, 581 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 582 vm_page_t m) 583 { 584 585 VM_OBJECT_ASSERT_WLOCKED(m->object); 586 if (bp->b_flags & B_CACHE) { 587 int base = (foff + off) & PAGE_MASK; 588 if (vm_page_is_valid(m, base, size) == 0) 589 bp->b_flags &= ~B_CACHE; 590 } 591 } 592 593 /* Wake up the buffer daemon if necessary */ 594 static __inline void 595 bd_wakeup(void) 596 { 597 598 mtx_lock(&bdlock); 599 if (bd_request == 0) { 600 bd_request = 1; 601 wakeup(&bd_request); 602 } 603 mtx_unlock(&bdlock); 604 } 605 606 /* 607 * bd_speedup - speedup the buffer cache flushing code 608 */ 609 void 610 bd_speedup(void) 611 { 612 int needwake; 613 614 mtx_lock(&bdlock); 615 needwake = 0; 616 if (bd_speedupreq == 0 || bd_request == 0) 617 needwake = 1; 618 bd_speedupreq = 1; 619 bd_request = 1; 620 if (needwake) 621 wakeup(&bd_request); 622 mtx_unlock(&bdlock); 623 } 624 625 #ifdef __i386__ 626 #define TRANSIENT_DENOM 5 627 #else 628 #define TRANSIENT_DENOM 10 629 #endif 630 631 /* 632 * Calculating buffer cache scaling values and reserve space for buffer 633 * headers. This is called during low level kernel initialization and 634 * may be called more then once. We CANNOT write to the memory area 635 * being reserved at this time. 636 */ 637 caddr_t 638 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 639 { 640 int tuned_nbuf; 641 long maxbuf, maxbuf_sz, buf_sz, biotmap_sz; 642 643 /* 644 * physmem_est is in pages. Convert it to kilobytes (assumes 645 * PAGE_SIZE is >= 1K) 646 */ 647 physmem_est = physmem_est * (PAGE_SIZE / 1024); 648 649 /* 650 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 651 * For the first 64MB of ram nominally allocate sufficient buffers to 652 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 653 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing 654 * the buffer cache we limit the eventual kva reservation to 655 * maxbcache bytes. 656 * 657 * factor represents the 1/4 x ram conversion. 658 */ 659 if (nbuf == 0) { 660 int factor = 4 * BKVASIZE / 1024; 661 662 nbuf = 50; 663 if (physmem_est > 4096) 664 nbuf += min((physmem_est - 4096) / factor, 665 65536 / factor); 666 if (physmem_est > 65536) 667 nbuf += min((physmem_est - 65536) * 2 / (factor * 5), 668 32 * 1024 * 1024 / (factor * 5)); 669 670 if (maxbcache && nbuf > maxbcache / BKVASIZE) 671 nbuf = maxbcache / BKVASIZE; 672 tuned_nbuf = 1; 673 } else 674 tuned_nbuf = 0; 675 676 /* XXX Avoid unsigned long overflows later on with maxbufspace. */ 677 maxbuf = (LONG_MAX / 3) / BKVASIZE; 678 if (nbuf > maxbuf) { 679 if (!tuned_nbuf) 680 printf("Warning: nbufs lowered from %d to %ld\n", nbuf, 681 maxbuf); 682 nbuf = maxbuf; 683 } 684 685 /* 686 * Ideal allocation size for the transient bio submap if 10% 687 * of the maximal space buffer map. This roughly corresponds 688 * to the amount of the buffer mapped for typical UFS load. 689 * 690 * Clip the buffer map to reserve space for the transient 691 * BIOs, if its extent is bigger than 90% (80% on i386) of the 692 * maximum buffer map extent on the platform. 693 * 694 * The fall-back to the maxbuf in case of maxbcache unset, 695 * allows to not trim the buffer KVA for the architectures 696 * with ample KVA space. 697 */ 698 if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) { 699 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE; 700 buf_sz = (long)nbuf * BKVASIZE; 701 if (buf_sz < maxbuf_sz / TRANSIENT_DENOM * 702 (TRANSIENT_DENOM - 1)) { 703 /* 704 * There is more KVA than memory. Do not 705 * adjust buffer map size, and assign the rest 706 * of maxbuf to transient map. 707 */ 708 biotmap_sz = maxbuf_sz - buf_sz; 709 } else { 710 /* 711 * Buffer map spans all KVA we could afford on 712 * this platform. Give 10% (20% on i386) of 713 * the buffer map to the transient bio map. 714 */ 715 biotmap_sz = buf_sz / TRANSIENT_DENOM; 716 buf_sz -= biotmap_sz; 717 } 718 if (biotmap_sz / INT_MAX > MAXPHYS) 719 bio_transient_maxcnt = INT_MAX; 720 else 721 bio_transient_maxcnt = biotmap_sz / MAXPHYS; 722 /* 723 * Artifically limit to 1024 simultaneous in-flight I/Os 724 * using the transient mapping. 725 */ 726 if (bio_transient_maxcnt > 1024) 727 bio_transient_maxcnt = 1024; 728 if (tuned_nbuf) 729 nbuf = buf_sz / BKVASIZE; 730 } 731 732 /* 733 * swbufs are used as temporary holders for I/O, such as paging I/O. 734 * We have no less then 16 and no more then 256. 735 */ 736 nswbuf = max(min(nbuf/4, 256), 16); 737 #ifdef NSWBUF_MIN 738 if (nswbuf < NSWBUF_MIN) 739 nswbuf = NSWBUF_MIN; 740 #endif 741 #ifdef DIRECTIO 742 ffs_rawread_setup(); 743 #endif 744 745 /* 746 * Reserve space for the buffer cache buffers 747 */ 748 swbuf = (void *)v; 749 v = (caddr_t)(swbuf + nswbuf); 750 buf = (void *)v; 751 v = (caddr_t)(buf + nbuf); 752 753 return(v); 754 } 755 756 /* Initialize the buffer subsystem. Called before use of any buffers. */ 757 void 758 bufinit(void) 759 { 760 struct buf *bp; 761 int i; 762 763 mtx_init(&bqclean, "bufq clean lock", NULL, MTX_DEF); 764 mtx_init(&bqdirty, "bufq dirty lock", NULL, MTX_DEF); 765 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 766 mtx_init(&nblock, "needsbuffer lock", NULL, MTX_DEF); 767 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 768 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF); 769 770 /* next, make a null set of free lists */ 771 for (i = 0; i < BUFFER_QUEUES; i++) 772 TAILQ_INIT(&bufqueues[i]); 773 774 /* finally, initialize each buffer header and stick on empty q */ 775 for (i = 0; i < nbuf; i++) { 776 bp = &buf[i]; 777 bzero(bp, sizeof *bp); 778 bp->b_flags = B_INVAL | B_INFREECNT; 779 bp->b_rcred = NOCRED; 780 bp->b_wcred = NOCRED; 781 bp->b_qindex = QUEUE_EMPTY; 782 bp->b_xflags = 0; 783 LIST_INIT(&bp->b_dep); 784 BUF_LOCKINIT(bp); 785 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 786 #ifdef INVARIANTS 787 bq_len[QUEUE_EMPTY]++; 788 #endif 789 } 790 791 /* 792 * maxbufspace is the absolute maximum amount of buffer space we are 793 * allowed to reserve in KVM and in real terms. The absolute maximum 794 * is nominally used by buf_daemon. hibufspace is the nominal maximum 795 * used by most other processes. The differential is required to 796 * ensure that buf_daemon is able to run when other processes might 797 * be blocked waiting for buffer space. 798 * 799 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 800 * this may result in KVM fragmentation which is not handled optimally 801 * by the system. 802 */ 803 maxbufspace = (long)nbuf * BKVASIZE; 804 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 805 lobufspace = hibufspace - MAXBSIZE; 806 807 /* 808 * Note: The 16 MiB upper limit for hirunningspace was chosen 809 * arbitrarily and may need further tuning. It corresponds to 810 * 128 outstanding write IO requests (if IO size is 128 KiB), 811 * which fits with many RAID controllers' tagged queuing limits. 812 * The lower 1 MiB limit is the historical upper limit for 813 * hirunningspace. 814 */ 815 hirunningspace = lmax(lmin(roundup(hibufspace / 64, MAXBSIZE), 816 16 * 1024 * 1024), 1024 * 1024); 817 lorunningspace = roundup((hirunningspace * 2) / 3, MAXBSIZE); 818 819 /* 820 * Limit the amount of malloc memory since it is wired permanently into 821 * the kernel space. Even though this is accounted for in the buffer 822 * allocation, we don't want the malloced region to grow uncontrolled. 823 * The malloc scheme improves memory utilization significantly on average 824 * (small) directories. 825 */ 826 maxbufmallocspace = hibufspace / 20; 827 828 /* 829 * Reduce the chance of a deadlock occuring by limiting the number 830 * of delayed-write dirty buffers we allow to stack up. 831 */ 832 hidirtybuffers = nbuf / 4 + 20; 833 dirtybufthresh = hidirtybuffers * 9 / 10; 834 numdirtybuffers = 0; 835 /* 836 * To support extreme low-memory systems, make sure hidirtybuffers cannot 837 * eat up all available buffer space. This occurs when our minimum cannot 838 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 839 * BKVASIZE'd buffers. 840 */ 841 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 842 hidirtybuffers >>= 1; 843 } 844 lodirtybuffers = hidirtybuffers / 2; 845 846 /* 847 * Try to keep the number of free buffers in the specified range, 848 * and give special processes (e.g. like buf_daemon) access to an 849 * emergency reserve. 850 */ 851 lofreebuffers = nbuf / 18 + 5; 852 hifreebuffers = 2 * lofreebuffers; 853 numfreebuffers = nbuf; 854 855 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ | 856 VM_ALLOC_NORMAL | VM_ALLOC_WIRED); 857 unmapped_buf = (caddr_t)kmem_alloc_nofault(kernel_map, MAXPHYS); 858 } 859 860 #ifdef INVARIANTS 861 static inline void 862 vfs_buf_check_mapped(struct buf *bp) 863 { 864 865 KASSERT((bp->b_flags & B_UNMAPPED) == 0, 866 ("mapped buf %p %x", bp, bp->b_flags)); 867 KASSERT(bp->b_kvabase != unmapped_buf, 868 ("mapped buf: b_kvabase was not updated %p", bp)); 869 KASSERT(bp->b_data != unmapped_buf, 870 ("mapped buf: b_data was not updated %p", bp)); 871 } 872 873 static inline void 874 vfs_buf_check_unmapped(struct buf *bp) 875 { 876 877 KASSERT((bp->b_flags & B_UNMAPPED) == B_UNMAPPED, 878 ("unmapped buf %p %x", bp, bp->b_flags)); 879 KASSERT(bp->b_kvabase == unmapped_buf, 880 ("unmapped buf: corrupted b_kvabase %p", bp)); 881 KASSERT(bp->b_data == unmapped_buf, 882 ("unmapped buf: corrupted b_data %p", bp)); 883 } 884 885 #define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp) 886 #define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp) 887 #else 888 #define BUF_CHECK_MAPPED(bp) do {} while (0) 889 #define BUF_CHECK_UNMAPPED(bp) do {} while (0) 890 #endif 891 892 static void 893 bpmap_qenter(struct buf *bp) 894 { 895 896 BUF_CHECK_MAPPED(bp); 897 898 /* 899 * bp->b_data is relative to bp->b_offset, but 900 * bp->b_offset may be offset into the first page. 901 */ 902 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data); 903 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages); 904 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 905 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 906 } 907 908 /* 909 * bfreekva() - free the kva allocation for a buffer. 910 * 911 * Since this call frees up buffer space, we call bufspacewakeup(). 912 */ 913 static void 914 bfreekva(struct buf *bp) 915 { 916 917 if (bp->b_kvasize == 0) 918 return; 919 920 atomic_add_int(&buffreekvacnt, 1); 921 atomic_subtract_long(&bufspace, bp->b_kvasize); 922 if ((bp->b_flags & B_UNMAPPED) == 0) { 923 BUF_CHECK_MAPPED(bp); 924 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, 925 bp->b_kvasize); 926 } else { 927 BUF_CHECK_UNMAPPED(bp); 928 if ((bp->b_flags & B_KVAALLOC) != 0) { 929 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvaalloc, 930 bp->b_kvasize); 931 } 932 atomic_subtract_long(&unmapped_bufspace, bp->b_kvasize); 933 bp->b_flags &= ~(B_UNMAPPED | B_KVAALLOC); 934 } 935 bp->b_kvasize = 0; 936 bufspacewakeup(); 937 } 938 939 /* 940 * binsfree: 941 * 942 * Insert the buffer into the appropriate free list. 943 */ 944 static void 945 binsfree(struct buf *bp, int qindex) 946 { 947 struct mtx *olock, *nlock; 948 949 BUF_ASSERT_XLOCKED(bp); 950 951 olock = bqlock(bp->b_qindex); 952 nlock = bqlock(qindex); 953 mtx_lock(olock); 954 /* Handle delayed bremfree() processing. */ 955 if (bp->b_flags & B_REMFREE) 956 bremfreel(bp); 957 958 if (bp->b_qindex != QUEUE_NONE) 959 panic("binsfree: free buffer onto another queue???"); 960 961 bp->b_qindex = qindex; 962 if (olock != nlock) { 963 mtx_unlock(olock); 964 mtx_lock(nlock); 965 } 966 if (bp->b_flags & B_AGE) 967 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 968 else 969 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 970 #ifdef INVARIANTS 971 bq_len[bp->b_qindex]++; 972 #endif 973 mtx_unlock(nlock); 974 975 /* 976 * Something we can maybe free or reuse. 977 */ 978 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 979 bufspacewakeup(); 980 981 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI)) 982 bufcountadd(bp); 983 } 984 985 /* 986 * bremfree: 987 * 988 * Mark the buffer for removal from the appropriate free list. 989 * 990 */ 991 void 992 bremfree(struct buf *bp) 993 { 994 995 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 996 KASSERT((bp->b_flags & B_REMFREE) == 0, 997 ("bremfree: buffer %p already marked for delayed removal.", bp)); 998 KASSERT(bp->b_qindex != QUEUE_NONE, 999 ("bremfree: buffer %p not on a queue.", bp)); 1000 BUF_ASSERT_XLOCKED(bp); 1001 1002 bp->b_flags |= B_REMFREE; 1003 bufcountsub(bp); 1004 } 1005 1006 /* 1007 * bremfreef: 1008 * 1009 * Force an immediate removal from a free list. Used only in nfs when 1010 * it abuses the b_freelist pointer. 1011 */ 1012 void 1013 bremfreef(struct buf *bp) 1014 { 1015 struct mtx *qlock; 1016 1017 qlock = bqlock(bp->b_qindex); 1018 mtx_lock(qlock); 1019 bremfreel(bp); 1020 mtx_unlock(qlock); 1021 } 1022 1023 /* 1024 * bremfreel: 1025 * 1026 * Removes a buffer from the free list, must be called with the 1027 * correct qlock held. 1028 */ 1029 static void 1030 bremfreel(struct buf *bp) 1031 { 1032 1033 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X", 1034 bp, bp->b_vp, bp->b_flags); 1035 KASSERT(bp->b_qindex != QUEUE_NONE, 1036 ("bremfreel: buffer %p not on a queue.", bp)); 1037 BUF_ASSERT_XLOCKED(bp); 1038 mtx_assert(bqlock(bp->b_qindex), MA_OWNED); 1039 1040 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 1041 #ifdef INVARIANTS 1042 KASSERT(bq_len[bp->b_qindex] >= 1, ("queue %d underflow", 1043 bp->b_qindex)); 1044 bq_len[bp->b_qindex]--; 1045 #endif 1046 bp->b_qindex = QUEUE_NONE; 1047 /* 1048 * If this was a delayed bremfree() we only need to remove the buffer 1049 * from the queue and return the stats are already done. 1050 */ 1051 if (bp->b_flags & B_REMFREE) { 1052 bp->b_flags &= ~B_REMFREE; 1053 return; 1054 } 1055 bufcountsub(bp); 1056 } 1057 1058 /* 1059 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 1060 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 1061 * the buffer is valid and we do not have to do anything. 1062 */ 1063 void 1064 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, 1065 int cnt, struct ucred * cred) 1066 { 1067 struct buf *rabp; 1068 int i; 1069 1070 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 1071 if (inmem(vp, *rablkno)) 1072 continue; 1073 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 1074 1075 if ((rabp->b_flags & B_CACHE) == 0) { 1076 if (!TD_IS_IDLETHREAD(curthread)) 1077 curthread->td_ru.ru_inblock++; 1078 rabp->b_flags |= B_ASYNC; 1079 rabp->b_flags &= ~B_INVAL; 1080 rabp->b_ioflags &= ~BIO_ERROR; 1081 rabp->b_iocmd = BIO_READ; 1082 if (rabp->b_rcred == NOCRED && cred != NOCRED) 1083 rabp->b_rcred = crhold(cred); 1084 vfs_busy_pages(rabp, 0); 1085 BUF_KERNPROC(rabp); 1086 rabp->b_iooffset = dbtob(rabp->b_blkno); 1087 bstrategy(rabp); 1088 } else { 1089 brelse(rabp); 1090 } 1091 } 1092 } 1093 1094 /* 1095 * Entry point for bread() and breadn() via #defines in sys/buf.h. 1096 * 1097 * Get a buffer with the specified data. Look in the cache first. We 1098 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 1099 * is set, the buffer is valid and we do not have to do anything, see 1100 * getblk(). Also starts asynchronous I/O on read-ahead blocks. 1101 */ 1102 int 1103 breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno, 1104 int *rabsize, int cnt, struct ucred *cred, int flags, struct buf **bpp) 1105 { 1106 struct buf *bp; 1107 int rv = 0, readwait = 0; 1108 1109 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 1110 /* 1111 * Can only return NULL if GB_LOCK_NOWAIT flag is specified. 1112 */ 1113 *bpp = bp = getblk(vp, blkno, size, 0, 0, flags); 1114 if (bp == NULL) 1115 return (EBUSY); 1116 1117 /* if not found in cache, do some I/O */ 1118 if ((bp->b_flags & B_CACHE) == 0) { 1119 if (!TD_IS_IDLETHREAD(curthread)) 1120 curthread->td_ru.ru_inblock++; 1121 bp->b_iocmd = BIO_READ; 1122 bp->b_flags &= ~B_INVAL; 1123 bp->b_ioflags &= ~BIO_ERROR; 1124 if (bp->b_rcred == NOCRED && cred != NOCRED) 1125 bp->b_rcred = crhold(cred); 1126 vfs_busy_pages(bp, 0); 1127 bp->b_iooffset = dbtob(bp->b_blkno); 1128 bstrategy(bp); 1129 ++readwait; 1130 } 1131 1132 breada(vp, rablkno, rabsize, cnt, cred); 1133 1134 if (readwait) { 1135 rv = bufwait(bp); 1136 } 1137 return (rv); 1138 } 1139 1140 /* 1141 * Write, release buffer on completion. (Done by iodone 1142 * if async). Do not bother writing anything if the buffer 1143 * is invalid. 1144 * 1145 * Note that we set B_CACHE here, indicating that buffer is 1146 * fully valid and thus cacheable. This is true even of NFS 1147 * now so we set it generally. This could be set either here 1148 * or in biodone() since the I/O is synchronous. We put it 1149 * here. 1150 */ 1151 int 1152 bufwrite(struct buf *bp) 1153 { 1154 int oldflags; 1155 struct vnode *vp; 1156 long space; 1157 int vp_md; 1158 1159 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1160 if (bp->b_flags & B_INVAL) { 1161 brelse(bp); 1162 return (0); 1163 } 1164 1165 if (bp->b_flags & B_BARRIER) 1166 barrierwrites++; 1167 1168 oldflags = bp->b_flags; 1169 1170 BUF_ASSERT_HELD(bp); 1171 1172 if (bp->b_pin_count > 0) 1173 bunpin_wait(bp); 1174 1175 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 1176 ("FFS background buffer should not get here %p", bp)); 1177 1178 vp = bp->b_vp; 1179 if (vp) 1180 vp_md = vp->v_vflag & VV_MD; 1181 else 1182 vp_md = 0; 1183 1184 /* 1185 * Mark the buffer clean. Increment the bufobj write count 1186 * before bundirty() call, to prevent other thread from seeing 1187 * empty dirty list and zero counter for writes in progress, 1188 * falsely indicating that the bufobj is clean. 1189 */ 1190 bufobj_wref(bp->b_bufobj); 1191 bundirty(bp); 1192 1193 bp->b_flags &= ~B_DONE; 1194 bp->b_ioflags &= ~BIO_ERROR; 1195 bp->b_flags |= B_CACHE; 1196 bp->b_iocmd = BIO_WRITE; 1197 1198 vfs_busy_pages(bp, 1); 1199 1200 /* 1201 * Normal bwrites pipeline writes 1202 */ 1203 bp->b_runningbufspace = bp->b_bufsize; 1204 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace); 1205 1206 if (!TD_IS_IDLETHREAD(curthread)) 1207 curthread->td_ru.ru_oublock++; 1208 if (oldflags & B_ASYNC) 1209 BUF_KERNPROC(bp); 1210 bp->b_iooffset = dbtob(bp->b_blkno); 1211 bstrategy(bp); 1212 1213 if ((oldflags & B_ASYNC) == 0) { 1214 int rtval = bufwait(bp); 1215 brelse(bp); 1216 return (rtval); 1217 } else if (space > hirunningspace) { 1218 /* 1219 * don't allow the async write to saturate the I/O 1220 * system. We will not deadlock here because 1221 * we are blocking waiting for I/O that is already in-progress 1222 * to complete. We do not block here if it is the update 1223 * or syncer daemon trying to clean up as that can lead 1224 * to deadlock. 1225 */ 1226 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 1227 waitrunningbufspace(); 1228 } 1229 1230 return (0); 1231 } 1232 1233 void 1234 bufbdflush(struct bufobj *bo, struct buf *bp) 1235 { 1236 struct buf *nbp; 1237 1238 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 1239 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 1240 altbufferflushes++; 1241 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 1242 BO_LOCK(bo); 1243 /* 1244 * Try to find a buffer to flush. 1245 */ 1246 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 1247 if ((nbp->b_vflags & BV_BKGRDINPROG) || 1248 BUF_LOCK(nbp, 1249 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 1250 continue; 1251 if (bp == nbp) 1252 panic("bdwrite: found ourselves"); 1253 BO_UNLOCK(bo); 1254 /* Don't countdeps with the bo lock held. */ 1255 if (buf_countdeps(nbp, 0)) { 1256 BO_LOCK(bo); 1257 BUF_UNLOCK(nbp); 1258 continue; 1259 } 1260 if (nbp->b_flags & B_CLUSTEROK) { 1261 vfs_bio_awrite(nbp); 1262 } else { 1263 bremfree(nbp); 1264 bawrite(nbp); 1265 } 1266 dirtybufferflushes++; 1267 break; 1268 } 1269 if (nbp == NULL) 1270 BO_UNLOCK(bo); 1271 } 1272 } 1273 1274 /* 1275 * Delayed write. (Buffer is marked dirty). Do not bother writing 1276 * anything if the buffer is marked invalid. 1277 * 1278 * Note that since the buffer must be completely valid, we can safely 1279 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 1280 * biodone() in order to prevent getblk from writing the buffer 1281 * out synchronously. 1282 */ 1283 void 1284 bdwrite(struct buf *bp) 1285 { 1286 struct thread *td = curthread; 1287 struct vnode *vp; 1288 struct bufobj *bo; 1289 1290 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1291 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1292 KASSERT((bp->b_flags & B_BARRIER) == 0, 1293 ("Barrier request in delayed write %p", bp)); 1294 BUF_ASSERT_HELD(bp); 1295 1296 if (bp->b_flags & B_INVAL) { 1297 brelse(bp); 1298 return; 1299 } 1300 1301 /* 1302 * If we have too many dirty buffers, don't create any more. 1303 * If we are wildly over our limit, then force a complete 1304 * cleanup. Otherwise, just keep the situation from getting 1305 * out of control. Note that we have to avoid a recursive 1306 * disaster and not try to clean up after our own cleanup! 1307 */ 1308 vp = bp->b_vp; 1309 bo = bp->b_bufobj; 1310 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 1311 td->td_pflags |= TDP_INBDFLUSH; 1312 BO_BDFLUSH(bo, bp); 1313 td->td_pflags &= ~TDP_INBDFLUSH; 1314 } else 1315 recursiveflushes++; 1316 1317 bdirty(bp); 1318 /* 1319 * Set B_CACHE, indicating that the buffer is fully valid. This is 1320 * true even of NFS now. 1321 */ 1322 bp->b_flags |= B_CACHE; 1323 1324 /* 1325 * This bmap keeps the system from needing to do the bmap later, 1326 * perhaps when the system is attempting to do a sync. Since it 1327 * is likely that the indirect block -- or whatever other datastructure 1328 * that the filesystem needs is still in memory now, it is a good 1329 * thing to do this. Note also, that if the pageout daemon is 1330 * requesting a sync -- there might not be enough memory to do 1331 * the bmap then... So, this is important to do. 1332 */ 1333 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 1334 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 1335 } 1336 1337 /* 1338 * Set the *dirty* buffer range based upon the VM system dirty 1339 * pages. 1340 * 1341 * Mark the buffer pages as clean. We need to do this here to 1342 * satisfy the vnode_pager and the pageout daemon, so that it 1343 * thinks that the pages have been "cleaned". Note that since 1344 * the pages are in a delayed write buffer -- the VFS layer 1345 * "will" see that the pages get written out on the next sync, 1346 * or perhaps the cluster will be completed. 1347 */ 1348 vfs_clean_pages_dirty_buf(bp); 1349 bqrelse(bp); 1350 1351 /* 1352 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 1353 * due to the softdep code. 1354 */ 1355 } 1356 1357 /* 1358 * bdirty: 1359 * 1360 * Turn buffer into delayed write request. We must clear BIO_READ and 1361 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 1362 * itself to properly update it in the dirty/clean lists. We mark it 1363 * B_DONE to ensure that any asynchronization of the buffer properly 1364 * clears B_DONE ( else a panic will occur later ). 1365 * 1366 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 1367 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 1368 * should only be called if the buffer is known-good. 1369 * 1370 * Since the buffer is not on a queue, we do not update the numfreebuffers 1371 * count. 1372 * 1373 * The buffer must be on QUEUE_NONE. 1374 */ 1375 void 1376 bdirty(struct buf *bp) 1377 { 1378 1379 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 1380 bp, bp->b_vp, bp->b_flags); 1381 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1382 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1383 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1384 BUF_ASSERT_HELD(bp); 1385 bp->b_flags &= ~(B_RELBUF); 1386 bp->b_iocmd = BIO_WRITE; 1387 1388 if ((bp->b_flags & B_DELWRI) == 0) { 1389 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 1390 reassignbuf(bp); 1391 bdirtyadd(); 1392 } 1393 } 1394 1395 /* 1396 * bundirty: 1397 * 1398 * Clear B_DELWRI for buffer. 1399 * 1400 * Since the buffer is not on a queue, we do not update the numfreebuffers 1401 * count. 1402 * 1403 * The buffer must be on QUEUE_NONE. 1404 */ 1405 1406 void 1407 bundirty(struct buf *bp) 1408 { 1409 1410 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1411 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1412 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1413 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1414 BUF_ASSERT_HELD(bp); 1415 1416 if (bp->b_flags & B_DELWRI) { 1417 bp->b_flags &= ~B_DELWRI; 1418 reassignbuf(bp); 1419 bdirtysub(); 1420 } 1421 /* 1422 * Since it is now being written, we can clear its deferred write flag. 1423 */ 1424 bp->b_flags &= ~B_DEFERRED; 1425 } 1426 1427 /* 1428 * bawrite: 1429 * 1430 * Asynchronous write. Start output on a buffer, but do not wait for 1431 * it to complete. The buffer is released when the output completes. 1432 * 1433 * bwrite() ( or the VOP routine anyway ) is responsible for handling 1434 * B_INVAL buffers. Not us. 1435 */ 1436 void 1437 bawrite(struct buf *bp) 1438 { 1439 1440 bp->b_flags |= B_ASYNC; 1441 (void) bwrite(bp); 1442 } 1443 1444 /* 1445 * babarrierwrite: 1446 * 1447 * Asynchronous barrier write. Start output on a buffer, but do not 1448 * wait for it to complete. Place a write barrier after this write so 1449 * that this buffer and all buffers written before it are committed to 1450 * the disk before any buffers written after this write are committed 1451 * to the disk. The buffer is released when the output completes. 1452 */ 1453 void 1454 babarrierwrite(struct buf *bp) 1455 { 1456 1457 bp->b_flags |= B_ASYNC | B_BARRIER; 1458 (void) bwrite(bp); 1459 } 1460 1461 /* 1462 * bbarrierwrite: 1463 * 1464 * Synchronous barrier write. Start output on a buffer and wait for 1465 * it to complete. Place a write barrier after this write so that 1466 * this buffer and all buffers written before it are committed to 1467 * the disk before any buffers written after this write are committed 1468 * to the disk. The buffer is released when the output completes. 1469 */ 1470 int 1471 bbarrierwrite(struct buf *bp) 1472 { 1473 1474 bp->b_flags |= B_BARRIER; 1475 return (bwrite(bp)); 1476 } 1477 1478 /* 1479 * bwillwrite: 1480 * 1481 * Called prior to the locking of any vnodes when we are expecting to 1482 * write. We do not want to starve the buffer cache with too many 1483 * dirty buffers so we block here. By blocking prior to the locking 1484 * of any vnodes we attempt to avoid the situation where a locked vnode 1485 * prevents the various system daemons from flushing related buffers. 1486 */ 1487 void 1488 bwillwrite(void) 1489 { 1490 1491 if (numdirtybuffers >= hidirtybuffers) { 1492 mtx_lock(&bdirtylock); 1493 while (numdirtybuffers >= hidirtybuffers) { 1494 bdirtywait = 1; 1495 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4), 1496 "flswai", 0); 1497 } 1498 mtx_unlock(&bdirtylock); 1499 } 1500 } 1501 1502 /* 1503 * Return true if we have too many dirty buffers. 1504 */ 1505 int 1506 buf_dirty_count_severe(void) 1507 { 1508 1509 return(numdirtybuffers >= hidirtybuffers); 1510 } 1511 1512 static __noinline int 1513 buf_vm_page_count_severe(void) 1514 { 1515 1516 KFAIL_POINT_CODE(DEBUG_FP, buf_pressure, return 1); 1517 1518 return vm_page_count_severe(); 1519 } 1520 1521 /* 1522 * brelse: 1523 * 1524 * Release a busy buffer and, if requested, free its resources. The 1525 * buffer will be stashed in the appropriate bufqueue[] allowing it 1526 * to be accessed later as a cache entity or reused for other purposes. 1527 */ 1528 void 1529 brelse(struct buf *bp) 1530 { 1531 int qindex; 1532 1533 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 1534 bp, bp->b_vp, bp->b_flags); 1535 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1536 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1537 1538 if (BUF_LOCKRECURSED(bp)) { 1539 /* 1540 * Do not process, in particular, do not handle the 1541 * B_INVAL/B_RELBUF and do not release to free list. 1542 */ 1543 BUF_UNLOCK(bp); 1544 return; 1545 } 1546 1547 if (bp->b_flags & B_MANAGED) { 1548 bqrelse(bp); 1549 return; 1550 } 1551 1552 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 1553 bp->b_error == EIO && !(bp->b_flags & B_INVAL)) { 1554 /* 1555 * Failed write, redirty. Must clear BIO_ERROR to prevent 1556 * pages from being scrapped. If the error is anything 1557 * other than an I/O error (EIO), assume that retrying 1558 * is futile. 1559 */ 1560 bp->b_ioflags &= ~BIO_ERROR; 1561 bdirty(bp); 1562 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 1563 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 1564 /* 1565 * Either a failed I/O or we were asked to free or not 1566 * cache the buffer. 1567 */ 1568 bp->b_flags |= B_INVAL; 1569 if (!LIST_EMPTY(&bp->b_dep)) 1570 buf_deallocate(bp); 1571 if (bp->b_flags & B_DELWRI) 1572 bdirtysub(); 1573 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1574 if ((bp->b_flags & B_VMIO) == 0) { 1575 if (bp->b_bufsize) 1576 allocbuf(bp, 0); 1577 if (bp->b_vp) 1578 brelvp(bp); 1579 } 1580 } 1581 1582 /* 1583 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1584 * is called with B_DELWRI set, the underlying pages may wind up 1585 * getting freed causing a previous write (bdwrite()) to get 'lost' 1586 * because pages associated with a B_DELWRI bp are marked clean. 1587 * 1588 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1589 * if B_DELWRI is set. 1590 * 1591 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1592 * on pages to return pages to the VM page queues. 1593 */ 1594 if (bp->b_flags & B_DELWRI) 1595 bp->b_flags &= ~B_RELBUF; 1596 else if (buf_vm_page_count_severe()) { 1597 /* 1598 * BKGRDINPROG can only be set with the buf and bufobj 1599 * locks both held. We tolerate a race to clear it here. 1600 */ 1601 if (!(bp->b_vflags & BV_BKGRDINPROG)) 1602 bp->b_flags |= B_RELBUF; 1603 } 1604 1605 /* 1606 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1607 * constituted, not even NFS buffers now. Two flags effect this. If 1608 * B_INVAL, the struct buf is invalidated but the VM object is kept 1609 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1610 * 1611 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 1612 * invalidated. BIO_ERROR cannot be set for a failed write unless the 1613 * buffer is also B_INVAL because it hits the re-dirtying code above. 1614 * 1615 * Normally we can do this whether a buffer is B_DELWRI or not. If 1616 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1617 * the commit state and we cannot afford to lose the buffer. If the 1618 * buffer has a background write in progress, we need to keep it 1619 * around to prevent it from being reconstituted and starting a second 1620 * background write. 1621 */ 1622 if ((bp->b_flags & B_VMIO) 1623 && !(bp->b_vp->v_mount != NULL && 1624 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 1625 !vn_isdisk(bp->b_vp, NULL) && 1626 (bp->b_flags & B_DELWRI)) 1627 ) { 1628 1629 int i, j, resid; 1630 vm_page_t m; 1631 off_t foff; 1632 vm_pindex_t poff; 1633 vm_object_t obj; 1634 1635 obj = bp->b_bufobj->bo_object; 1636 1637 /* 1638 * Get the base offset and length of the buffer. Note that 1639 * in the VMIO case if the buffer block size is not 1640 * page-aligned then b_data pointer may not be page-aligned. 1641 * But our b_pages[] array *IS* page aligned. 1642 * 1643 * block sizes less then DEV_BSIZE (usually 512) are not 1644 * supported due to the page granularity bits (m->valid, 1645 * m->dirty, etc...). 1646 * 1647 * See man buf(9) for more information 1648 */ 1649 resid = bp->b_bufsize; 1650 foff = bp->b_offset; 1651 for (i = 0; i < bp->b_npages; i++) { 1652 int had_bogus = 0; 1653 1654 m = bp->b_pages[i]; 1655 1656 /* 1657 * If we hit a bogus page, fixup *all* the bogus pages 1658 * now. 1659 */ 1660 if (m == bogus_page) { 1661 poff = OFF_TO_IDX(bp->b_offset); 1662 had_bogus = 1; 1663 1664 VM_OBJECT_RLOCK(obj); 1665 for (j = i; j < bp->b_npages; j++) { 1666 vm_page_t mtmp; 1667 mtmp = bp->b_pages[j]; 1668 if (mtmp == bogus_page) { 1669 mtmp = vm_page_lookup(obj, poff + j); 1670 if (!mtmp) { 1671 panic("brelse: page missing\n"); 1672 } 1673 bp->b_pages[j] = mtmp; 1674 } 1675 } 1676 VM_OBJECT_RUNLOCK(obj); 1677 1678 if ((bp->b_flags & (B_INVAL | B_UNMAPPED)) == 0) { 1679 BUF_CHECK_MAPPED(bp); 1680 pmap_qenter( 1681 trunc_page((vm_offset_t)bp->b_data), 1682 bp->b_pages, bp->b_npages); 1683 } 1684 m = bp->b_pages[i]; 1685 } 1686 if ((bp->b_flags & B_NOCACHE) || 1687 (bp->b_ioflags & BIO_ERROR && 1688 bp->b_iocmd == BIO_READ)) { 1689 int poffset = foff & PAGE_MASK; 1690 int presid = resid > (PAGE_SIZE - poffset) ? 1691 (PAGE_SIZE - poffset) : resid; 1692 1693 KASSERT(presid >= 0, ("brelse: extra page")); 1694 VM_OBJECT_WLOCK(obj); 1695 vm_page_set_invalid(m, poffset, presid); 1696 VM_OBJECT_WUNLOCK(obj); 1697 if (had_bogus) 1698 printf("avoided corruption bug in bogus_page/brelse code\n"); 1699 } 1700 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1701 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1702 } 1703 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1704 vfs_vmio_release(bp); 1705 1706 } else if (bp->b_flags & B_VMIO) { 1707 1708 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1709 vfs_vmio_release(bp); 1710 } 1711 1712 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) { 1713 if (bp->b_bufsize != 0) 1714 allocbuf(bp, 0); 1715 if (bp->b_vp != NULL) 1716 brelvp(bp); 1717 } 1718 1719 /* 1720 * If the buffer has junk contents signal it and eventually 1721 * clean up B_DELWRI and diassociate the vnode so that gbincore() 1722 * doesn't find it. 1723 */ 1724 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 1725 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 1726 bp->b_flags |= B_INVAL; 1727 if (bp->b_flags & B_INVAL) { 1728 if (bp->b_flags & B_DELWRI) 1729 bundirty(bp); 1730 if (bp->b_vp) 1731 brelvp(bp); 1732 } 1733 1734 /* buffers with no memory */ 1735 if (bp->b_bufsize == 0) { 1736 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1737 if (bp->b_vflags & BV_BKGRDINPROG) 1738 panic("losing buffer 1"); 1739 if (bp->b_kvasize) 1740 qindex = QUEUE_EMPTYKVA; 1741 else 1742 qindex = QUEUE_EMPTY; 1743 bp->b_flags |= B_AGE; 1744 /* buffers with junk contents */ 1745 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 1746 (bp->b_ioflags & BIO_ERROR)) { 1747 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1748 if (bp->b_vflags & BV_BKGRDINPROG) 1749 panic("losing buffer 2"); 1750 qindex = QUEUE_CLEAN; 1751 bp->b_flags |= B_AGE; 1752 /* remaining buffers */ 1753 } else if (bp->b_flags & B_DELWRI) 1754 qindex = QUEUE_DIRTY; 1755 else 1756 qindex = QUEUE_CLEAN; 1757 1758 binsfree(bp, qindex); 1759 1760 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 1761 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1762 panic("brelse: not dirty"); 1763 /* unlock */ 1764 BUF_UNLOCK(bp); 1765 } 1766 1767 /* 1768 * Release a buffer back to the appropriate queue but do not try to free 1769 * it. The buffer is expected to be used again soon. 1770 * 1771 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1772 * biodone() to requeue an async I/O on completion. It is also used when 1773 * known good buffers need to be requeued but we think we may need the data 1774 * again soon. 1775 * 1776 * XXX we should be able to leave the B_RELBUF hint set on completion. 1777 */ 1778 void 1779 bqrelse(struct buf *bp) 1780 { 1781 int qindex; 1782 1783 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1784 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1785 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1786 1787 if (BUF_LOCKRECURSED(bp)) { 1788 /* do not release to free list */ 1789 BUF_UNLOCK(bp); 1790 return; 1791 } 1792 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1793 1794 if (bp->b_flags & B_MANAGED) { 1795 if (bp->b_flags & B_REMFREE) 1796 bremfreef(bp); 1797 goto out; 1798 } 1799 1800 /* buffers with stale but valid contents */ 1801 if (bp->b_flags & B_DELWRI) { 1802 qindex = QUEUE_DIRTY; 1803 } else { 1804 if ((bp->b_flags & B_DELWRI) == 0 && 1805 (bp->b_xflags & BX_VNDIRTY)) 1806 panic("bqrelse: not dirty"); 1807 /* 1808 * BKGRDINPROG can only be set with the buf and bufobj 1809 * locks both held. We tolerate a race to clear it here. 1810 */ 1811 if (buf_vm_page_count_severe() && 1812 (bp->b_vflags & BV_BKGRDINPROG) == 0) { 1813 /* 1814 * We are too low on memory, we have to try to free 1815 * the buffer (most importantly: the wired pages 1816 * making up its backing store) *now*. 1817 */ 1818 brelse(bp); 1819 return; 1820 } 1821 qindex = QUEUE_CLEAN; 1822 } 1823 binsfree(bp, qindex); 1824 1825 out: 1826 /* unlock */ 1827 BUF_UNLOCK(bp); 1828 } 1829 1830 /* Give pages used by the bp back to the VM system (where possible) */ 1831 static void 1832 vfs_vmio_release(struct buf *bp) 1833 { 1834 int i; 1835 vm_page_t m; 1836 1837 if ((bp->b_flags & B_UNMAPPED) == 0) { 1838 BUF_CHECK_MAPPED(bp); 1839 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages); 1840 } else 1841 BUF_CHECK_UNMAPPED(bp); 1842 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 1843 for (i = 0; i < bp->b_npages; i++) { 1844 m = bp->b_pages[i]; 1845 bp->b_pages[i] = NULL; 1846 /* 1847 * In order to keep page LRU ordering consistent, put 1848 * everything on the inactive queue. 1849 */ 1850 vm_page_lock(m); 1851 vm_page_unwire(m, 0); 1852 /* 1853 * We don't mess with busy pages, it is 1854 * the responsibility of the process that 1855 * busied the pages to deal with them. 1856 */ 1857 if ((m->oflags & VPO_BUSY) == 0 && m->busy == 0 && 1858 m->wire_count == 0) { 1859 /* 1860 * Might as well free the page if we can and it has 1861 * no valid data. We also free the page if the 1862 * buffer was used for direct I/O 1863 */ 1864 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid) { 1865 vm_page_free(m); 1866 } else if (bp->b_flags & B_DIRECT) { 1867 vm_page_try_to_free(m); 1868 } else if (buf_vm_page_count_severe()) { 1869 vm_page_try_to_cache(m); 1870 } 1871 } 1872 vm_page_unlock(m); 1873 } 1874 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 1875 1876 if (bp->b_bufsize) { 1877 bufspacewakeup(); 1878 bp->b_bufsize = 0; 1879 } 1880 bp->b_npages = 0; 1881 bp->b_flags &= ~B_VMIO; 1882 if (bp->b_vp) 1883 brelvp(bp); 1884 } 1885 1886 /* 1887 * Check to see if a block at a particular lbn is available for a clustered 1888 * write. 1889 */ 1890 static int 1891 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 1892 { 1893 struct buf *bpa; 1894 int match; 1895 1896 match = 0; 1897 1898 /* If the buf isn't in core skip it */ 1899 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 1900 return (0); 1901 1902 /* If the buf is busy we don't want to wait for it */ 1903 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1904 return (0); 1905 1906 /* Only cluster with valid clusterable delayed write buffers */ 1907 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 1908 (B_DELWRI | B_CLUSTEROK)) 1909 goto done; 1910 1911 if (bpa->b_bufsize != size) 1912 goto done; 1913 1914 /* 1915 * Check to see if it is in the expected place on disk and that the 1916 * block has been mapped. 1917 */ 1918 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 1919 match = 1; 1920 done: 1921 BUF_UNLOCK(bpa); 1922 return (match); 1923 } 1924 1925 /* 1926 * vfs_bio_awrite: 1927 * 1928 * Implement clustered async writes for clearing out B_DELWRI buffers. 1929 * This is much better then the old way of writing only one buffer at 1930 * a time. Note that we may not be presented with the buffers in the 1931 * correct order, so we search for the cluster in both directions. 1932 */ 1933 int 1934 vfs_bio_awrite(struct buf *bp) 1935 { 1936 struct bufobj *bo; 1937 int i; 1938 int j; 1939 daddr_t lblkno = bp->b_lblkno; 1940 struct vnode *vp = bp->b_vp; 1941 int ncl; 1942 int nwritten; 1943 int size; 1944 int maxcl; 1945 int gbflags; 1946 1947 bo = &vp->v_bufobj; 1948 gbflags = (bp->b_flags & B_UNMAPPED) != 0 ? GB_UNMAPPED : 0; 1949 /* 1950 * right now we support clustered writing only to regular files. If 1951 * we find a clusterable block we could be in the middle of a cluster 1952 * rather then at the beginning. 1953 */ 1954 if ((vp->v_type == VREG) && 1955 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1956 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1957 1958 size = vp->v_mount->mnt_stat.f_iosize; 1959 maxcl = MAXPHYS / size; 1960 1961 BO_RLOCK(bo); 1962 for (i = 1; i < maxcl; i++) 1963 if (vfs_bio_clcheck(vp, size, lblkno + i, 1964 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 1965 break; 1966 1967 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 1968 if (vfs_bio_clcheck(vp, size, lblkno - j, 1969 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 1970 break; 1971 BO_RUNLOCK(bo); 1972 --j; 1973 ncl = i + j; 1974 /* 1975 * this is a possible cluster write 1976 */ 1977 if (ncl != 1) { 1978 BUF_UNLOCK(bp); 1979 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl, 1980 gbflags); 1981 return (nwritten); 1982 } 1983 } 1984 bremfree(bp); 1985 bp->b_flags |= B_ASYNC; 1986 /* 1987 * default (old) behavior, writing out only one block 1988 * 1989 * XXX returns b_bufsize instead of b_bcount for nwritten? 1990 */ 1991 nwritten = bp->b_bufsize; 1992 (void) bwrite(bp); 1993 1994 return (nwritten); 1995 } 1996 1997 static void 1998 setbufkva(struct buf *bp, vm_offset_t addr, int maxsize, int gbflags) 1999 { 2000 2001 KASSERT((bp->b_flags & (B_UNMAPPED | B_KVAALLOC)) == 0 && 2002 bp->b_kvasize == 0, ("call bfreekva(%p)", bp)); 2003 if ((gbflags & GB_UNMAPPED) == 0) { 2004 bp->b_kvabase = (caddr_t)addr; 2005 } else if ((gbflags & GB_KVAALLOC) != 0) { 2006 KASSERT((gbflags & GB_UNMAPPED) != 0, 2007 ("GB_KVAALLOC without GB_UNMAPPED")); 2008 bp->b_kvaalloc = (caddr_t)addr; 2009 bp->b_flags |= B_UNMAPPED | B_KVAALLOC; 2010 atomic_add_long(&unmapped_bufspace, bp->b_kvasize); 2011 } 2012 bp->b_kvasize = maxsize; 2013 } 2014 2015 /* 2016 * Allocate the buffer KVA and set b_kvasize. Also set b_kvabase if 2017 * needed. 2018 */ 2019 static int 2020 allocbufkva(struct buf *bp, int maxsize, int gbflags) 2021 { 2022 vm_offset_t addr; 2023 2024 bfreekva(bp); 2025 addr = 0; 2026 2027 if (vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr)) { 2028 /* 2029 * Buffer map is too fragmented. Request the caller 2030 * to defragment the map. 2031 */ 2032 atomic_add_int(&bufdefragcnt, 1); 2033 return (1); 2034 } 2035 setbufkva(bp, addr, maxsize, gbflags); 2036 atomic_add_long(&bufspace, bp->b_kvasize); 2037 return (0); 2038 } 2039 2040 /* 2041 * Ask the bufdaemon for help, or act as bufdaemon itself, when a 2042 * locked vnode is supplied. 2043 */ 2044 static void 2045 getnewbuf_bufd_help(struct vnode *vp, int gbflags, int slpflag, int slptimeo, 2046 int defrag) 2047 { 2048 struct thread *td; 2049 char *waitmsg; 2050 int fl, flags, norunbuf; 2051 2052 mtx_assert(&bqclean, MA_OWNED); 2053 2054 if (defrag) { 2055 flags = VFS_BIO_NEED_BUFSPACE; 2056 waitmsg = "nbufkv"; 2057 } else if (bufspace >= hibufspace) { 2058 waitmsg = "nbufbs"; 2059 flags = VFS_BIO_NEED_BUFSPACE; 2060 } else { 2061 waitmsg = "newbuf"; 2062 flags = VFS_BIO_NEED_ANY; 2063 } 2064 mtx_lock(&nblock); 2065 needsbuffer |= flags; 2066 mtx_unlock(&nblock); 2067 mtx_unlock(&bqclean); 2068 2069 bd_speedup(); /* heeeelp */ 2070 if ((gbflags & GB_NOWAIT_BD) != 0) 2071 return; 2072 2073 td = curthread; 2074 mtx_lock(&nblock); 2075 while (needsbuffer & flags) { 2076 if (vp != NULL && (td->td_pflags & TDP_BUFNEED) == 0) { 2077 mtx_unlock(&nblock); 2078 /* 2079 * getblk() is called with a vnode locked, and 2080 * some majority of the dirty buffers may as 2081 * well belong to the vnode. Flushing the 2082 * buffers there would make a progress that 2083 * cannot be achieved by the buf_daemon, that 2084 * cannot lock the vnode. 2085 */ 2086 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) | 2087 (td->td_pflags & TDP_NORUNNINGBUF); 2088 /* play bufdaemon */ 2089 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF; 2090 fl = buf_flush(vp, flushbufqtarget); 2091 td->td_pflags &= norunbuf; 2092 mtx_lock(&nblock); 2093 if (fl != 0) 2094 continue; 2095 if ((needsbuffer & flags) == 0) 2096 break; 2097 } 2098 if (msleep(&needsbuffer, &nblock, (PRIBIO + 4) | slpflag, 2099 waitmsg, slptimeo)) 2100 break; 2101 } 2102 mtx_unlock(&nblock); 2103 } 2104 2105 static void 2106 getnewbuf_reuse_bp(struct buf *bp, int qindex) 2107 { 2108 2109 CTR6(KTR_BUF, "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d " 2110 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags, 2111 bp->b_kvasize, bp->b_bufsize, qindex); 2112 mtx_assert(&bqclean, MA_NOTOWNED); 2113 2114 /* 2115 * Note: we no longer distinguish between VMIO and non-VMIO 2116 * buffers. 2117 */ 2118 KASSERT((bp->b_flags & B_DELWRI) == 0, 2119 ("delwri buffer %p found in queue %d", bp, qindex)); 2120 2121 if (qindex == QUEUE_CLEAN) { 2122 if (bp->b_flags & B_VMIO) { 2123 bp->b_flags &= ~B_ASYNC; 2124 vfs_vmio_release(bp); 2125 } 2126 if (bp->b_vp != NULL) 2127 brelvp(bp); 2128 } 2129 2130 /* 2131 * Get the rest of the buffer freed up. b_kva* is still valid 2132 * after this operation. 2133 */ 2134 2135 if (bp->b_rcred != NOCRED) { 2136 crfree(bp->b_rcred); 2137 bp->b_rcred = NOCRED; 2138 } 2139 if (bp->b_wcred != NOCRED) { 2140 crfree(bp->b_wcred); 2141 bp->b_wcred = NOCRED; 2142 } 2143 if (!LIST_EMPTY(&bp->b_dep)) 2144 buf_deallocate(bp); 2145 if (bp->b_vflags & BV_BKGRDINPROG) 2146 panic("losing buffer 3"); 2147 KASSERT(bp->b_vp == NULL, ("bp: %p still has vnode %p. qindex: %d", 2148 bp, bp->b_vp, qindex)); 2149 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 2150 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags)); 2151 2152 if (bp->b_bufsize) 2153 allocbuf(bp, 0); 2154 2155 bp->b_flags &= B_UNMAPPED | B_KVAALLOC; 2156 bp->b_ioflags = 0; 2157 bp->b_xflags = 0; 2158 KASSERT((bp->b_flags & B_INFREECNT) == 0, 2159 ("buf %p still counted as free?", bp)); 2160 bp->b_vflags = 0; 2161 bp->b_vp = NULL; 2162 bp->b_blkno = bp->b_lblkno = 0; 2163 bp->b_offset = NOOFFSET; 2164 bp->b_iodone = 0; 2165 bp->b_error = 0; 2166 bp->b_resid = 0; 2167 bp->b_bcount = 0; 2168 bp->b_npages = 0; 2169 bp->b_dirtyoff = bp->b_dirtyend = 0; 2170 bp->b_bufobj = NULL; 2171 bp->b_pin_count = 0; 2172 bp->b_fsprivate1 = NULL; 2173 bp->b_fsprivate2 = NULL; 2174 bp->b_fsprivate3 = NULL; 2175 2176 LIST_INIT(&bp->b_dep); 2177 } 2178 2179 static int flushingbufs; 2180 2181 static struct buf * 2182 getnewbuf_scan(int maxsize, int defrag, int unmapped, int metadata) 2183 { 2184 struct buf *bp, *nbp; 2185 int nqindex, qindex, pass; 2186 2187 KASSERT(!unmapped || !defrag, ("both unmapped and defrag")); 2188 2189 pass = 1; 2190 restart: 2191 atomic_add_int(&getnewbufrestarts, 1); 2192 2193 /* 2194 * Setup for scan. If we do not have enough free buffers, 2195 * we setup a degenerate case that immediately fails. Note 2196 * that if we are specially marked process, we are allowed to 2197 * dip into our reserves. 2198 * 2199 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 2200 * for the allocation of the mapped buffer. For unmapped, the 2201 * easiest is to start with EMPTY outright. 2202 * 2203 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 2204 * However, there are a number of cases (defragging, reusing, ...) 2205 * where we cannot backup. 2206 */ 2207 nbp = NULL; 2208 mtx_lock(&bqclean); 2209 if (!defrag && unmapped) { 2210 nqindex = QUEUE_EMPTY; 2211 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 2212 } 2213 if (nbp == NULL) { 2214 nqindex = QUEUE_EMPTYKVA; 2215 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 2216 } 2217 2218 /* 2219 * If no EMPTYKVA buffers and we are either defragging or 2220 * reusing, locate a CLEAN buffer to free or reuse. If 2221 * bufspace useage is low skip this step so we can allocate a 2222 * new buffer. 2223 */ 2224 if (nbp == NULL && (defrag || bufspace >= lobufspace)) { 2225 nqindex = QUEUE_CLEAN; 2226 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2227 } 2228 2229 /* 2230 * If we could not find or were not allowed to reuse a CLEAN 2231 * buffer, check to see if it is ok to use an EMPTY buffer. 2232 * We can only use an EMPTY buffer if allocating its KVA would 2233 * not otherwise run us out of buffer space. No KVA is needed 2234 * for the unmapped allocation. 2235 */ 2236 if (nbp == NULL && defrag == 0 && (bufspace + maxsize < hibufspace || 2237 metadata)) { 2238 nqindex = QUEUE_EMPTY; 2239 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 2240 } 2241 2242 /* 2243 * All available buffers might be clean, retry ignoring the 2244 * lobufspace as the last resort. 2245 */ 2246 if (nbp == NULL && !TAILQ_EMPTY(&bufqueues[QUEUE_CLEAN])) { 2247 nqindex = QUEUE_CLEAN; 2248 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2249 } 2250 2251 /* 2252 * Run scan, possibly freeing data and/or kva mappings on the fly 2253 * depending. 2254 */ 2255 while ((bp = nbp) != NULL) { 2256 qindex = nqindex; 2257 2258 /* 2259 * Calculate next bp (we can only use it if we do not 2260 * block or do other fancy things). 2261 */ 2262 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 2263 switch (qindex) { 2264 case QUEUE_EMPTY: 2265 nqindex = QUEUE_EMPTYKVA; 2266 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 2267 if (nbp != NULL) 2268 break; 2269 /* FALLTHROUGH */ 2270 case QUEUE_EMPTYKVA: 2271 nqindex = QUEUE_CLEAN; 2272 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 2273 if (nbp != NULL) 2274 break; 2275 /* FALLTHROUGH */ 2276 case QUEUE_CLEAN: 2277 if (metadata && pass == 1) { 2278 pass = 2; 2279 nqindex = QUEUE_EMPTY; 2280 nbp = TAILQ_FIRST( 2281 &bufqueues[QUEUE_EMPTY]); 2282 } 2283 /* 2284 * nbp is NULL. 2285 */ 2286 break; 2287 } 2288 } 2289 /* 2290 * If we are defragging then we need a buffer with 2291 * b_kvasize != 0. XXX this situation should no longer 2292 * occur, if defrag is non-zero the buffer's b_kvasize 2293 * should also be non-zero at this point. XXX 2294 */ 2295 if (defrag && bp->b_kvasize == 0) { 2296 printf("Warning: defrag empty buffer %p\n", bp); 2297 continue; 2298 } 2299 2300 /* 2301 * Start freeing the bp. This is somewhat involved. nbp 2302 * remains valid only for QUEUE_EMPTY[KVA] bp's. 2303 */ 2304 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2305 continue; 2306 /* 2307 * BKGRDINPROG can only be set with the buf and bufobj 2308 * locks both held. We tolerate a race to clear it here. 2309 */ 2310 if (bp->b_vflags & BV_BKGRDINPROG) { 2311 BUF_UNLOCK(bp); 2312 continue; 2313 } 2314 2315 KASSERT(bp->b_qindex == qindex, 2316 ("getnewbuf: inconsistent queue %d bp %p", qindex, bp)); 2317 2318 bremfreel(bp); 2319 mtx_unlock(&bqclean); 2320 /* 2321 * NOTE: nbp is now entirely invalid. We can only restart 2322 * the scan from this point on. 2323 */ 2324 2325 getnewbuf_reuse_bp(bp, qindex); 2326 mtx_assert(&bqclean, MA_NOTOWNED); 2327 2328 /* 2329 * If we are defragging then free the buffer. 2330 */ 2331 if (defrag) { 2332 bp->b_flags |= B_INVAL; 2333 bfreekva(bp); 2334 brelse(bp); 2335 defrag = 0; 2336 goto restart; 2337 } 2338 2339 /* 2340 * Notify any waiters for the buffer lock about 2341 * identity change by freeing the buffer. 2342 */ 2343 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp)) { 2344 bp->b_flags |= B_INVAL; 2345 bfreekva(bp); 2346 brelse(bp); 2347 goto restart; 2348 } 2349 2350 if (metadata) 2351 break; 2352 2353 /* 2354 * If we are overcomitted then recover the buffer and its 2355 * KVM space. This occurs in rare situations when multiple 2356 * processes are blocked in getnewbuf() or allocbuf(). 2357 */ 2358 if (bufspace >= hibufspace) 2359 flushingbufs = 1; 2360 if (flushingbufs && bp->b_kvasize != 0) { 2361 bp->b_flags |= B_INVAL; 2362 bfreekva(bp); 2363 brelse(bp); 2364 goto restart; 2365 } 2366 if (bufspace < lobufspace) 2367 flushingbufs = 0; 2368 break; 2369 } 2370 return (bp); 2371 } 2372 2373 /* 2374 * getnewbuf: 2375 * 2376 * Find and initialize a new buffer header, freeing up existing buffers 2377 * in the bufqueues as necessary. The new buffer is returned locked. 2378 * 2379 * Important: B_INVAL is not set. If the caller wishes to throw the 2380 * buffer away, the caller must set B_INVAL prior to calling brelse(). 2381 * 2382 * We block if: 2383 * We have insufficient buffer headers 2384 * We have insufficient buffer space 2385 * buffer_arena is too fragmented ( space reservation fails ) 2386 * If we have to flush dirty buffers ( but we try to avoid this ) 2387 */ 2388 static struct buf * 2389 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int size, int maxsize, 2390 int gbflags) 2391 { 2392 struct buf *bp; 2393 int defrag, metadata; 2394 2395 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 2396 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 2397 if (!unmapped_buf_allowed) 2398 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC); 2399 2400 defrag = 0; 2401 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 || 2402 vp->v_type == VCHR) 2403 metadata = 1; 2404 else 2405 metadata = 0; 2406 /* 2407 * We can't afford to block since we might be holding a vnode lock, 2408 * which may prevent system daemons from running. We deal with 2409 * low-memory situations by proactively returning memory and running 2410 * async I/O rather then sync I/O. 2411 */ 2412 atomic_add_int(&getnewbufcalls, 1); 2413 atomic_subtract_int(&getnewbufrestarts, 1); 2414 restart: 2415 bp = getnewbuf_scan(maxsize, defrag, (gbflags & (GB_UNMAPPED | 2416 GB_KVAALLOC)) == GB_UNMAPPED, metadata); 2417 if (bp != NULL) 2418 defrag = 0; 2419 2420 /* 2421 * If we exhausted our list, sleep as appropriate. We may have to 2422 * wakeup various daemons and write out some dirty buffers. 2423 * 2424 * Generally we are sleeping due to insufficient buffer space. 2425 */ 2426 if (bp == NULL) { 2427 mtx_assert(&bqclean, MA_OWNED); 2428 getnewbuf_bufd_help(vp, gbflags, slpflag, slptimeo, defrag); 2429 mtx_assert(&bqclean, MA_NOTOWNED); 2430 } else if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == GB_UNMAPPED) { 2431 mtx_assert(&bqclean, MA_NOTOWNED); 2432 2433 bfreekva(bp); 2434 bp->b_flags |= B_UNMAPPED; 2435 bp->b_kvabase = bp->b_data = unmapped_buf; 2436 bp->b_kvasize = maxsize; 2437 atomic_add_long(&bufspace, bp->b_kvasize); 2438 atomic_add_long(&unmapped_bufspace, bp->b_kvasize); 2439 atomic_add_int(&bufreusecnt, 1); 2440 } else { 2441 mtx_assert(&bqclean, MA_NOTOWNED); 2442 2443 /* 2444 * We finally have a valid bp. We aren't quite out of the 2445 * woods, we still have to reserve kva space. In order 2446 * to keep fragmentation sane we only allocate kva in 2447 * BKVASIZE chunks. 2448 */ 2449 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2450 2451 if (maxsize != bp->b_kvasize || (bp->b_flags & (B_UNMAPPED | 2452 B_KVAALLOC)) == B_UNMAPPED) { 2453 if (allocbufkva(bp, maxsize, gbflags)) { 2454 defrag = 1; 2455 bp->b_flags |= B_INVAL; 2456 brelse(bp); 2457 goto restart; 2458 } 2459 atomic_add_int(&bufreusecnt, 1); 2460 } else if ((bp->b_flags & B_KVAALLOC) != 0 && 2461 (gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == 0) { 2462 /* 2463 * If the reused buffer has KVA allocated, 2464 * reassign b_kvaalloc to b_kvabase. 2465 */ 2466 bp->b_kvabase = bp->b_kvaalloc; 2467 bp->b_flags &= ~B_KVAALLOC; 2468 atomic_subtract_long(&unmapped_bufspace, 2469 bp->b_kvasize); 2470 atomic_add_int(&bufreusecnt, 1); 2471 } else if ((bp->b_flags & (B_UNMAPPED | B_KVAALLOC)) == 0 && 2472 (gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == (GB_UNMAPPED | 2473 GB_KVAALLOC)) { 2474 /* 2475 * The case of reused buffer already have KVA 2476 * mapped, but the request is for unmapped 2477 * buffer with KVA allocated. 2478 */ 2479 bp->b_kvaalloc = bp->b_kvabase; 2480 bp->b_data = bp->b_kvabase = unmapped_buf; 2481 bp->b_flags |= B_UNMAPPED | B_KVAALLOC; 2482 atomic_add_long(&unmapped_bufspace, 2483 bp->b_kvasize); 2484 atomic_add_int(&bufreusecnt, 1); 2485 } 2486 if ((gbflags & GB_UNMAPPED) == 0) { 2487 bp->b_saveaddr = bp->b_kvabase; 2488 bp->b_data = bp->b_saveaddr; 2489 bp->b_flags &= ~B_UNMAPPED; 2490 BUF_CHECK_MAPPED(bp); 2491 } 2492 } 2493 return (bp); 2494 } 2495 2496 /* 2497 * buf_daemon: 2498 * 2499 * buffer flushing daemon. Buffers are normally flushed by the 2500 * update daemon but if it cannot keep up this process starts to 2501 * take the load in an attempt to prevent getnewbuf() from blocking. 2502 */ 2503 2504 static struct kproc_desc buf_kp = { 2505 "bufdaemon", 2506 buf_daemon, 2507 &bufdaemonproc 2508 }; 2509 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 2510 2511 static int 2512 buf_flush(struct vnode *vp, int target) 2513 { 2514 int flushed; 2515 2516 flushed = flushbufqueues(vp, target, 0); 2517 if (flushed == 0) { 2518 /* 2519 * Could not find any buffers without rollback 2520 * dependencies, so just write the first one 2521 * in the hopes of eventually making progress. 2522 */ 2523 if (vp != NULL && target > 2) 2524 target /= 2; 2525 flushbufqueues(vp, target, 1); 2526 } 2527 return (flushed); 2528 } 2529 2530 static void 2531 buf_daemon() 2532 { 2533 int lodirty; 2534 2535 /* 2536 * This process needs to be suspended prior to shutdown sync. 2537 */ 2538 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2539 SHUTDOWN_PRI_LAST); 2540 2541 /* 2542 * This process is allowed to take the buffer cache to the limit 2543 */ 2544 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 2545 mtx_lock(&bdlock); 2546 for (;;) { 2547 bd_request = 0; 2548 mtx_unlock(&bdlock); 2549 2550 kproc_suspend_check(bufdaemonproc); 2551 lodirty = lodirtybuffers; 2552 if (bd_speedupreq) { 2553 lodirty = numdirtybuffers / 2; 2554 bd_speedupreq = 0; 2555 } 2556 /* 2557 * Do the flush. Limit the amount of in-transit I/O we 2558 * allow to build up, otherwise we would completely saturate 2559 * the I/O system. 2560 */ 2561 while (numdirtybuffers > lodirty) { 2562 if (buf_flush(NULL, numdirtybuffers - lodirty) == 0) 2563 break; 2564 kern_yield(PRI_USER); 2565 } 2566 2567 /* 2568 * Only clear bd_request if we have reached our low water 2569 * mark. The buf_daemon normally waits 1 second and 2570 * then incrementally flushes any dirty buffers that have 2571 * built up, within reason. 2572 * 2573 * If we were unable to hit our low water mark and couldn't 2574 * find any flushable buffers, we sleep for a short period 2575 * to avoid endless loops on unlockable buffers. 2576 */ 2577 mtx_lock(&bdlock); 2578 if (numdirtybuffers <= lodirtybuffers) { 2579 /* 2580 * We reached our low water mark, reset the 2581 * request and sleep until we are needed again. 2582 * The sleep is just so the suspend code works. 2583 */ 2584 bd_request = 0; 2585 /* 2586 * Do an extra wakeup in case dirty threshold 2587 * changed via sysctl and the explicit transition 2588 * out of shortfall was missed. 2589 */ 2590 bdirtywakeup(); 2591 if (runningbufspace <= lorunningspace) 2592 runningwakeup(); 2593 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 2594 } else { 2595 /* 2596 * We couldn't find any flushable dirty buffers but 2597 * still have too many dirty buffers, we 2598 * have to sleep and try again. (rare) 2599 */ 2600 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 2601 } 2602 } 2603 } 2604 2605 /* 2606 * flushbufqueues: 2607 * 2608 * Try to flush a buffer in the dirty queue. We must be careful to 2609 * free up B_INVAL buffers instead of write them, which NFS is 2610 * particularly sensitive to. 2611 */ 2612 static int flushwithdeps = 0; 2613 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 2614 0, "Number of buffers flushed with dependecies that require rollbacks"); 2615 2616 static int 2617 flushbufqueues(struct vnode *lvp, int target, int flushdeps) 2618 { 2619 struct buf *sentinel; 2620 struct vnode *vp; 2621 struct mount *mp; 2622 struct buf *bp; 2623 int hasdeps; 2624 int flushed; 2625 int queue; 2626 2627 flushed = 0; 2628 queue = QUEUE_DIRTY; 2629 bp = NULL; 2630 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 2631 sentinel->b_qindex = QUEUE_SENTINEL; 2632 mtx_lock(&bqdirty); 2633 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist); 2634 while (flushed != target) { 2635 bp = TAILQ_NEXT(sentinel, b_freelist); 2636 if (bp != NULL) { 2637 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2638 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel, 2639 b_freelist); 2640 } else 2641 break; 2642 /* 2643 * Skip sentinels inserted by other invocations of the 2644 * flushbufqueues(), taking care to not reorder them. 2645 */ 2646 if (bp->b_qindex == QUEUE_SENTINEL) 2647 continue; 2648 /* 2649 * Only flush the buffers that belong to the 2650 * vnode locked by the curthread. 2651 */ 2652 if (lvp != NULL && bp->b_vp != lvp) 2653 continue; 2654 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2655 continue; 2656 if (bp->b_pin_count > 0) { 2657 BUF_UNLOCK(bp); 2658 continue; 2659 } 2660 /* 2661 * BKGRDINPROG can only be set with the buf and bufobj 2662 * locks both held. We tolerate a race to clear it here. 2663 */ 2664 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 2665 (bp->b_flags & B_DELWRI) == 0) { 2666 BUF_UNLOCK(bp); 2667 continue; 2668 } 2669 if (bp->b_flags & B_INVAL) { 2670 bremfreel(bp); 2671 mtx_unlock(&bqdirty); 2672 brelse(bp); 2673 flushed++; 2674 mtx_lock(&bqdirty); 2675 continue; 2676 } 2677 2678 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 2679 if (flushdeps == 0) { 2680 BUF_UNLOCK(bp); 2681 continue; 2682 } 2683 hasdeps = 1; 2684 } else 2685 hasdeps = 0; 2686 /* 2687 * We must hold the lock on a vnode before writing 2688 * one of its buffers. Otherwise we may confuse, or 2689 * in the case of a snapshot vnode, deadlock the 2690 * system. 2691 * 2692 * The lock order here is the reverse of the normal 2693 * of vnode followed by buf lock. This is ok because 2694 * the NOWAIT will prevent deadlock. 2695 */ 2696 vp = bp->b_vp; 2697 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 2698 BUF_UNLOCK(bp); 2699 continue; 2700 } 2701 if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT | LK_CANRECURSE) == 0) { 2702 mtx_unlock(&bqdirty); 2703 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 2704 bp, bp->b_vp, bp->b_flags); 2705 if (curproc == bufdaemonproc) 2706 vfs_bio_awrite(bp); 2707 else { 2708 bremfree(bp); 2709 bwrite(bp); 2710 notbufdflushes++; 2711 } 2712 vn_finished_write(mp); 2713 VOP_UNLOCK(vp, 0); 2714 flushwithdeps += hasdeps; 2715 flushed++; 2716 2717 /* 2718 * Sleeping on runningbufspace while holding 2719 * vnode lock leads to deadlock. 2720 */ 2721 if (curproc == bufdaemonproc && 2722 runningbufspace > hirunningspace) 2723 waitrunningbufspace(); 2724 mtx_lock(&bqdirty); 2725 continue; 2726 } 2727 vn_finished_write(mp); 2728 BUF_UNLOCK(bp); 2729 } 2730 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2731 mtx_unlock(&bqdirty); 2732 free(sentinel, M_TEMP); 2733 return (flushed); 2734 } 2735 2736 /* 2737 * Check to see if a block is currently memory resident. 2738 */ 2739 struct buf * 2740 incore(struct bufobj *bo, daddr_t blkno) 2741 { 2742 struct buf *bp; 2743 2744 BO_RLOCK(bo); 2745 bp = gbincore(bo, blkno); 2746 BO_RUNLOCK(bo); 2747 return (bp); 2748 } 2749 2750 /* 2751 * Returns true if no I/O is needed to access the 2752 * associated VM object. This is like incore except 2753 * it also hunts around in the VM system for the data. 2754 */ 2755 2756 static int 2757 inmem(struct vnode * vp, daddr_t blkno) 2758 { 2759 vm_object_t obj; 2760 vm_offset_t toff, tinc, size; 2761 vm_page_t m; 2762 vm_ooffset_t off; 2763 2764 ASSERT_VOP_LOCKED(vp, "inmem"); 2765 2766 if (incore(&vp->v_bufobj, blkno)) 2767 return 1; 2768 if (vp->v_mount == NULL) 2769 return 0; 2770 obj = vp->v_object; 2771 if (obj == NULL) 2772 return (0); 2773 2774 size = PAGE_SIZE; 2775 if (size > vp->v_mount->mnt_stat.f_iosize) 2776 size = vp->v_mount->mnt_stat.f_iosize; 2777 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2778 2779 VM_OBJECT_RLOCK(obj); 2780 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2781 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2782 if (!m) 2783 goto notinmem; 2784 tinc = size; 2785 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2786 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2787 if (vm_page_is_valid(m, 2788 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2789 goto notinmem; 2790 } 2791 VM_OBJECT_RUNLOCK(obj); 2792 return 1; 2793 2794 notinmem: 2795 VM_OBJECT_RUNLOCK(obj); 2796 return (0); 2797 } 2798 2799 /* 2800 * Set the dirty range for a buffer based on the status of the dirty 2801 * bits in the pages comprising the buffer. The range is limited 2802 * to the size of the buffer. 2803 * 2804 * Tell the VM system that the pages associated with this buffer 2805 * are clean. This is used for delayed writes where the data is 2806 * going to go to disk eventually without additional VM intevention. 2807 * 2808 * Note that while we only really need to clean through to b_bcount, we 2809 * just go ahead and clean through to b_bufsize. 2810 */ 2811 static void 2812 vfs_clean_pages_dirty_buf(struct buf *bp) 2813 { 2814 vm_ooffset_t foff, noff, eoff; 2815 vm_page_t m; 2816 int i; 2817 2818 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 2819 return; 2820 2821 foff = bp->b_offset; 2822 KASSERT(bp->b_offset != NOOFFSET, 2823 ("vfs_clean_pages_dirty_buf: no buffer offset")); 2824 2825 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 2826 vfs_drain_busy_pages(bp); 2827 vfs_setdirty_locked_object(bp); 2828 for (i = 0; i < bp->b_npages; i++) { 2829 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2830 eoff = noff; 2831 if (eoff > bp->b_offset + bp->b_bufsize) 2832 eoff = bp->b_offset + bp->b_bufsize; 2833 m = bp->b_pages[i]; 2834 vfs_page_set_validclean(bp, foff, m); 2835 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 2836 foff = noff; 2837 } 2838 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 2839 } 2840 2841 static void 2842 vfs_setdirty_locked_object(struct buf *bp) 2843 { 2844 vm_object_t object; 2845 int i; 2846 2847 object = bp->b_bufobj->bo_object; 2848 VM_OBJECT_ASSERT_WLOCKED(object); 2849 2850 /* 2851 * We qualify the scan for modified pages on whether the 2852 * object has been flushed yet. 2853 */ 2854 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) { 2855 vm_offset_t boffset; 2856 vm_offset_t eoffset; 2857 2858 /* 2859 * test the pages to see if they have been modified directly 2860 * by users through the VM system. 2861 */ 2862 for (i = 0; i < bp->b_npages; i++) 2863 vm_page_test_dirty(bp->b_pages[i]); 2864 2865 /* 2866 * Calculate the encompassing dirty range, boffset and eoffset, 2867 * (eoffset - boffset) bytes. 2868 */ 2869 2870 for (i = 0; i < bp->b_npages; i++) { 2871 if (bp->b_pages[i]->dirty) 2872 break; 2873 } 2874 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2875 2876 for (i = bp->b_npages - 1; i >= 0; --i) { 2877 if (bp->b_pages[i]->dirty) { 2878 break; 2879 } 2880 } 2881 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2882 2883 /* 2884 * Fit it to the buffer. 2885 */ 2886 2887 if (eoffset > bp->b_bcount) 2888 eoffset = bp->b_bcount; 2889 2890 /* 2891 * If we have a good dirty range, merge with the existing 2892 * dirty range. 2893 */ 2894 2895 if (boffset < eoffset) { 2896 if (bp->b_dirtyoff > boffset) 2897 bp->b_dirtyoff = boffset; 2898 if (bp->b_dirtyend < eoffset) 2899 bp->b_dirtyend = eoffset; 2900 } 2901 } 2902 } 2903 2904 /* 2905 * Allocate the KVA mapping for an existing buffer. It handles the 2906 * cases of both B_UNMAPPED buffer, and buffer with the preallocated 2907 * KVA which is not mapped (B_KVAALLOC). 2908 */ 2909 static void 2910 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags) 2911 { 2912 struct buf *scratch_bp; 2913 int bsize, maxsize, need_mapping, need_kva; 2914 off_t offset; 2915 2916 need_mapping = (bp->b_flags & B_UNMAPPED) != 0 && 2917 (gbflags & GB_UNMAPPED) == 0; 2918 need_kva = (bp->b_flags & (B_KVAALLOC | B_UNMAPPED)) == B_UNMAPPED && 2919 (gbflags & GB_KVAALLOC) != 0; 2920 if (!need_mapping && !need_kva) 2921 return; 2922 2923 BUF_CHECK_UNMAPPED(bp); 2924 2925 if (need_mapping && (bp->b_flags & B_KVAALLOC) != 0) { 2926 /* 2927 * Buffer is not mapped, but the KVA was already 2928 * reserved at the time of the instantiation. Use the 2929 * allocated space. 2930 */ 2931 bp->b_flags &= ~B_KVAALLOC; 2932 KASSERT(bp->b_kvaalloc != 0, ("kvaalloc == 0")); 2933 bp->b_kvabase = bp->b_kvaalloc; 2934 atomic_subtract_long(&unmapped_bufspace, bp->b_kvasize); 2935 goto has_addr; 2936 } 2937 2938 /* 2939 * Calculate the amount of the address space we would reserve 2940 * if the buffer was mapped. 2941 */ 2942 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize; 2943 offset = blkno * bsize; 2944 maxsize = size + (offset & PAGE_MASK); 2945 maxsize = imax(maxsize, bsize); 2946 2947 mapping_loop: 2948 if (allocbufkva(bp, maxsize, gbflags)) { 2949 /* 2950 * Request defragmentation. getnewbuf() returns us the 2951 * allocated space by the scratch buffer KVA. 2952 */ 2953 scratch_bp = getnewbuf(bp->b_vp, 0, 0, size, maxsize, gbflags | 2954 (GB_UNMAPPED | GB_KVAALLOC)); 2955 if (scratch_bp == NULL) { 2956 if ((gbflags & GB_NOWAIT_BD) != 0) { 2957 /* 2958 * XXXKIB: defragmentation cannot 2959 * succeed, not sure what else to do. 2960 */ 2961 panic("GB_NOWAIT_BD and B_UNMAPPED %p", bp); 2962 } 2963 atomic_add_int(&mappingrestarts, 1); 2964 goto mapping_loop; 2965 } 2966 KASSERT((scratch_bp->b_flags & B_KVAALLOC) != 0, 2967 ("scratch bp !B_KVAALLOC %p", scratch_bp)); 2968 setbufkva(bp, (vm_offset_t)scratch_bp->b_kvaalloc, 2969 scratch_bp->b_kvasize, gbflags); 2970 2971 /* Get rid of the scratch buffer. */ 2972 scratch_bp->b_kvasize = 0; 2973 scratch_bp->b_flags |= B_INVAL; 2974 scratch_bp->b_flags &= ~(B_UNMAPPED | B_KVAALLOC); 2975 brelse(scratch_bp); 2976 } 2977 if (!need_mapping) 2978 return; 2979 2980 has_addr: 2981 bp->b_saveaddr = bp->b_kvabase; 2982 bp->b_data = bp->b_saveaddr; /* b_offset is handled by bpmap_qenter */ 2983 bp->b_flags &= ~B_UNMAPPED; 2984 BUF_CHECK_MAPPED(bp); 2985 bpmap_qenter(bp); 2986 } 2987 2988 /* 2989 * getblk: 2990 * 2991 * Get a block given a specified block and offset into a file/device. 2992 * The buffers B_DONE bit will be cleared on return, making it almost 2993 * ready for an I/O initiation. B_INVAL may or may not be set on 2994 * return. The caller should clear B_INVAL prior to initiating a 2995 * READ. 2996 * 2997 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2998 * an existing buffer. 2999 * 3000 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 3001 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 3002 * and then cleared based on the backing VM. If the previous buffer is 3003 * non-0-sized but invalid, B_CACHE will be cleared. 3004 * 3005 * If getblk() must create a new buffer, the new buffer is returned with 3006 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 3007 * case it is returned with B_INVAL clear and B_CACHE set based on the 3008 * backing VM. 3009 * 3010 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 3011 * B_CACHE bit is clear. 3012 * 3013 * What this means, basically, is that the caller should use B_CACHE to 3014 * determine whether the buffer is fully valid or not and should clear 3015 * B_INVAL prior to issuing a read. If the caller intends to validate 3016 * the buffer by loading its data area with something, the caller needs 3017 * to clear B_INVAL. If the caller does this without issuing an I/O, 3018 * the caller should set B_CACHE ( as an optimization ), else the caller 3019 * should issue the I/O and biodone() will set B_CACHE if the I/O was 3020 * a write attempt or if it was a successfull read. If the caller 3021 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 3022 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 3023 */ 3024 struct buf * 3025 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3026 int flags) 3027 { 3028 struct buf *bp; 3029 struct bufobj *bo; 3030 int bsize, error, maxsize, vmio; 3031 off_t offset; 3032 3033 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 3034 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3035 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3036 ASSERT_VOP_LOCKED(vp, "getblk"); 3037 if (size > MAXBSIZE) 3038 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 3039 if (!unmapped_buf_allowed) 3040 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3041 3042 bo = &vp->v_bufobj; 3043 loop: 3044 BO_RLOCK(bo); 3045 bp = gbincore(bo, blkno); 3046 if (bp != NULL) { 3047 int lockflags; 3048 /* 3049 * Buffer is in-core. If the buffer is not busy nor managed, 3050 * it must be on a queue. 3051 */ 3052 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 3053 3054 if (flags & GB_LOCK_NOWAIT) 3055 lockflags |= LK_NOWAIT; 3056 3057 error = BUF_TIMELOCK(bp, lockflags, 3058 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo); 3059 3060 /* 3061 * If we slept and got the lock we have to restart in case 3062 * the buffer changed identities. 3063 */ 3064 if (error == ENOLCK) 3065 goto loop; 3066 /* We timed out or were interrupted. */ 3067 else if (error) 3068 return (NULL); 3069 /* If recursed, assume caller knows the rules. */ 3070 else if (BUF_LOCKRECURSED(bp)) 3071 goto end; 3072 3073 /* 3074 * The buffer is locked. B_CACHE is cleared if the buffer is 3075 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 3076 * and for a VMIO buffer B_CACHE is adjusted according to the 3077 * backing VM cache. 3078 */ 3079 if (bp->b_flags & B_INVAL) 3080 bp->b_flags &= ~B_CACHE; 3081 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 3082 bp->b_flags |= B_CACHE; 3083 if (bp->b_flags & B_MANAGED) 3084 MPASS(bp->b_qindex == QUEUE_NONE); 3085 else 3086 bremfree(bp); 3087 3088 /* 3089 * check for size inconsistencies for non-VMIO case. 3090 */ 3091 if (bp->b_bcount != size) { 3092 if ((bp->b_flags & B_VMIO) == 0 || 3093 (size > bp->b_kvasize)) { 3094 if (bp->b_flags & B_DELWRI) { 3095 /* 3096 * If buffer is pinned and caller does 3097 * not want sleep waiting for it to be 3098 * unpinned, bail out 3099 * */ 3100 if (bp->b_pin_count > 0) { 3101 if (flags & GB_LOCK_NOWAIT) { 3102 bqrelse(bp); 3103 return (NULL); 3104 } else { 3105 bunpin_wait(bp); 3106 } 3107 } 3108 bp->b_flags |= B_NOCACHE; 3109 bwrite(bp); 3110 } else { 3111 if (LIST_EMPTY(&bp->b_dep)) { 3112 bp->b_flags |= B_RELBUF; 3113 brelse(bp); 3114 } else { 3115 bp->b_flags |= B_NOCACHE; 3116 bwrite(bp); 3117 } 3118 } 3119 goto loop; 3120 } 3121 } 3122 3123 /* 3124 * Handle the case of unmapped buffer which should 3125 * become mapped, or the buffer for which KVA 3126 * reservation is requested. 3127 */ 3128 bp_unmapped_get_kva(bp, blkno, size, flags); 3129 3130 /* 3131 * If the size is inconsistant in the VMIO case, we can resize 3132 * the buffer. This might lead to B_CACHE getting set or 3133 * cleared. If the size has not changed, B_CACHE remains 3134 * unchanged from its previous state. 3135 */ 3136 if (bp->b_bcount != size) 3137 allocbuf(bp, size); 3138 3139 KASSERT(bp->b_offset != NOOFFSET, 3140 ("getblk: no buffer offset")); 3141 3142 /* 3143 * A buffer with B_DELWRI set and B_CACHE clear must 3144 * be committed before we can return the buffer in 3145 * order to prevent the caller from issuing a read 3146 * ( due to B_CACHE not being set ) and overwriting 3147 * it. 3148 * 3149 * Most callers, including NFS and FFS, need this to 3150 * operate properly either because they assume they 3151 * can issue a read if B_CACHE is not set, or because 3152 * ( for example ) an uncached B_DELWRI might loop due 3153 * to softupdates re-dirtying the buffer. In the latter 3154 * case, B_CACHE is set after the first write completes, 3155 * preventing further loops. 3156 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 3157 * above while extending the buffer, we cannot allow the 3158 * buffer to remain with B_CACHE set after the write 3159 * completes or it will represent a corrupt state. To 3160 * deal with this we set B_NOCACHE to scrap the buffer 3161 * after the write. 3162 * 3163 * We might be able to do something fancy, like setting 3164 * B_CACHE in bwrite() except if B_DELWRI is already set, 3165 * so the below call doesn't set B_CACHE, but that gets real 3166 * confusing. This is much easier. 3167 */ 3168 3169 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 3170 bp->b_flags |= B_NOCACHE; 3171 bwrite(bp); 3172 goto loop; 3173 } 3174 bp->b_flags &= ~B_DONE; 3175 } else { 3176 /* 3177 * Buffer is not in-core, create new buffer. The buffer 3178 * returned by getnewbuf() is locked. Note that the returned 3179 * buffer is also considered valid (not marked B_INVAL). 3180 */ 3181 BO_RUNLOCK(bo); 3182 /* 3183 * If the user does not want us to create the buffer, bail out 3184 * here. 3185 */ 3186 if (flags & GB_NOCREAT) 3187 return NULL; 3188 if (numfreebuffers == 0 && TD_IS_IDLETHREAD(curthread)) 3189 return NULL; 3190 3191 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize; 3192 offset = blkno * bsize; 3193 vmio = vp->v_object != NULL; 3194 if (vmio) { 3195 maxsize = size + (offset & PAGE_MASK); 3196 } else { 3197 maxsize = size; 3198 /* Do not allow non-VMIO notmapped buffers. */ 3199 flags &= ~GB_UNMAPPED; 3200 } 3201 maxsize = imax(maxsize, bsize); 3202 3203 bp = getnewbuf(vp, slpflag, slptimeo, size, maxsize, flags); 3204 if (bp == NULL) { 3205 if (slpflag || slptimeo) 3206 return NULL; 3207 goto loop; 3208 } 3209 3210 /* 3211 * This code is used to make sure that a buffer is not 3212 * created while the getnewbuf routine is blocked. 3213 * This can be a problem whether the vnode is locked or not. 3214 * If the buffer is created out from under us, we have to 3215 * throw away the one we just created. 3216 * 3217 * Note: this must occur before we associate the buffer 3218 * with the vp especially considering limitations in 3219 * the splay tree implementation when dealing with duplicate 3220 * lblkno's. 3221 */ 3222 BO_LOCK(bo); 3223 if (gbincore(bo, blkno)) { 3224 BO_UNLOCK(bo); 3225 bp->b_flags |= B_INVAL; 3226 brelse(bp); 3227 goto loop; 3228 } 3229 3230 /* 3231 * Insert the buffer into the hash, so that it can 3232 * be found by incore. 3233 */ 3234 bp->b_blkno = bp->b_lblkno = blkno; 3235 bp->b_offset = offset; 3236 bgetvp(vp, bp); 3237 BO_UNLOCK(bo); 3238 3239 /* 3240 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 3241 * buffer size starts out as 0, B_CACHE will be set by 3242 * allocbuf() for the VMIO case prior to it testing the 3243 * backing store for validity. 3244 */ 3245 3246 if (vmio) { 3247 bp->b_flags |= B_VMIO; 3248 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 3249 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 3250 bp, vp->v_object, bp->b_bufobj->bo_object)); 3251 } else { 3252 bp->b_flags &= ~B_VMIO; 3253 KASSERT(bp->b_bufobj->bo_object == NULL, 3254 ("ARGH! has b_bufobj->bo_object %p %p\n", 3255 bp, bp->b_bufobj->bo_object)); 3256 BUF_CHECK_MAPPED(bp); 3257 } 3258 3259 allocbuf(bp, size); 3260 bp->b_flags &= ~B_DONE; 3261 } 3262 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 3263 BUF_ASSERT_HELD(bp); 3264 end: 3265 KASSERT(bp->b_bufobj == bo, 3266 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 3267 return (bp); 3268 } 3269 3270 /* 3271 * Get an empty, disassociated buffer of given size. The buffer is initially 3272 * set to B_INVAL. 3273 */ 3274 struct buf * 3275 geteblk(int size, int flags) 3276 { 3277 struct buf *bp; 3278 int maxsize; 3279 3280 maxsize = (size + BKVAMASK) & ~BKVAMASK; 3281 while ((bp = getnewbuf(NULL, 0, 0, size, maxsize, flags)) == NULL) { 3282 if ((flags & GB_NOWAIT_BD) && 3283 (curthread->td_pflags & TDP_BUFNEED) != 0) 3284 return (NULL); 3285 } 3286 allocbuf(bp, size); 3287 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 3288 BUF_ASSERT_HELD(bp); 3289 return (bp); 3290 } 3291 3292 3293 /* 3294 * This code constitutes the buffer memory from either anonymous system 3295 * memory (in the case of non-VMIO operations) or from an associated 3296 * VM object (in the case of VMIO operations). This code is able to 3297 * resize a buffer up or down. 3298 * 3299 * Note that this code is tricky, and has many complications to resolve 3300 * deadlock or inconsistant data situations. Tread lightly!!! 3301 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 3302 * the caller. Calling this code willy nilly can result in the loss of data. 3303 * 3304 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 3305 * B_CACHE for the non-VMIO case. 3306 */ 3307 3308 int 3309 allocbuf(struct buf *bp, int size) 3310 { 3311 int newbsize, mbsize; 3312 int i; 3313 3314 BUF_ASSERT_HELD(bp); 3315 3316 if (bp->b_kvasize < size) 3317 panic("allocbuf: buffer too small"); 3318 3319 if ((bp->b_flags & B_VMIO) == 0) { 3320 caddr_t origbuf; 3321 int origbufsize; 3322 /* 3323 * Just get anonymous memory from the kernel. Don't 3324 * mess with B_CACHE. 3325 */ 3326 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3327 if (bp->b_flags & B_MALLOC) 3328 newbsize = mbsize; 3329 else 3330 newbsize = round_page(size); 3331 3332 if (newbsize < bp->b_bufsize) { 3333 /* 3334 * malloced buffers are not shrunk 3335 */ 3336 if (bp->b_flags & B_MALLOC) { 3337 if (newbsize) { 3338 bp->b_bcount = size; 3339 } else { 3340 free(bp->b_data, M_BIOBUF); 3341 if (bp->b_bufsize) { 3342 atomic_subtract_long( 3343 &bufmallocspace, 3344 bp->b_bufsize); 3345 bufspacewakeup(); 3346 bp->b_bufsize = 0; 3347 } 3348 bp->b_saveaddr = bp->b_kvabase; 3349 bp->b_data = bp->b_saveaddr; 3350 bp->b_bcount = 0; 3351 bp->b_flags &= ~B_MALLOC; 3352 } 3353 return 1; 3354 } 3355 vm_hold_free_pages(bp, newbsize); 3356 } else if (newbsize > bp->b_bufsize) { 3357 /* 3358 * We only use malloced memory on the first allocation. 3359 * and revert to page-allocated memory when the buffer 3360 * grows. 3361 */ 3362 /* 3363 * There is a potential smp race here that could lead 3364 * to bufmallocspace slightly passing the max. It 3365 * is probably extremely rare and not worth worrying 3366 * over. 3367 */ 3368 if ( (bufmallocspace < maxbufmallocspace) && 3369 (bp->b_bufsize == 0) && 3370 (mbsize <= PAGE_SIZE/2)) { 3371 3372 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 3373 bp->b_bufsize = mbsize; 3374 bp->b_bcount = size; 3375 bp->b_flags |= B_MALLOC; 3376 atomic_add_long(&bufmallocspace, mbsize); 3377 return 1; 3378 } 3379 origbuf = NULL; 3380 origbufsize = 0; 3381 /* 3382 * If the buffer is growing on its other-than-first allocation, 3383 * then we revert to the page-allocation scheme. 3384 */ 3385 if (bp->b_flags & B_MALLOC) { 3386 origbuf = bp->b_data; 3387 origbufsize = bp->b_bufsize; 3388 bp->b_data = bp->b_kvabase; 3389 if (bp->b_bufsize) { 3390 atomic_subtract_long(&bufmallocspace, 3391 bp->b_bufsize); 3392 bufspacewakeup(); 3393 bp->b_bufsize = 0; 3394 } 3395 bp->b_flags &= ~B_MALLOC; 3396 newbsize = round_page(newbsize); 3397 } 3398 vm_hold_load_pages( 3399 bp, 3400 (vm_offset_t) bp->b_data + bp->b_bufsize, 3401 (vm_offset_t) bp->b_data + newbsize); 3402 if (origbuf) { 3403 bcopy(origbuf, bp->b_data, origbufsize); 3404 free(origbuf, M_BIOBUF); 3405 } 3406 } 3407 } else { 3408 int desiredpages; 3409 3410 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3411 desiredpages = (size == 0) ? 0 : 3412 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 3413 3414 if (bp->b_flags & B_MALLOC) 3415 panic("allocbuf: VMIO buffer can't be malloced"); 3416 /* 3417 * Set B_CACHE initially if buffer is 0 length or will become 3418 * 0-length. 3419 */ 3420 if (size == 0 || bp->b_bufsize == 0) 3421 bp->b_flags |= B_CACHE; 3422 3423 if (newbsize < bp->b_bufsize) { 3424 /* 3425 * DEV_BSIZE aligned new buffer size is less then the 3426 * DEV_BSIZE aligned existing buffer size. Figure out 3427 * if we have to remove any pages. 3428 */ 3429 if (desiredpages < bp->b_npages) { 3430 vm_page_t m; 3431 3432 if ((bp->b_flags & B_UNMAPPED) == 0) { 3433 BUF_CHECK_MAPPED(bp); 3434 pmap_qremove((vm_offset_t)trunc_page( 3435 (vm_offset_t)bp->b_data) + 3436 (desiredpages << PAGE_SHIFT), 3437 (bp->b_npages - desiredpages)); 3438 } else 3439 BUF_CHECK_UNMAPPED(bp); 3440 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 3441 for (i = desiredpages; i < bp->b_npages; i++) { 3442 /* 3443 * the page is not freed here -- it 3444 * is the responsibility of 3445 * vnode_pager_setsize 3446 */ 3447 m = bp->b_pages[i]; 3448 KASSERT(m != bogus_page, 3449 ("allocbuf: bogus page found")); 3450 while (vm_page_sleep_if_busy(m, TRUE, 3451 "biodep")) 3452 continue; 3453 3454 bp->b_pages[i] = NULL; 3455 vm_page_lock(m); 3456 vm_page_unwire(m, 0); 3457 vm_page_unlock(m); 3458 } 3459 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 3460 bp->b_npages = desiredpages; 3461 } 3462 } else if (size > bp->b_bcount) { 3463 /* 3464 * We are growing the buffer, possibly in a 3465 * byte-granular fashion. 3466 */ 3467 vm_object_t obj; 3468 vm_offset_t toff; 3469 vm_offset_t tinc; 3470 3471 /* 3472 * Step 1, bring in the VM pages from the object, 3473 * allocating them if necessary. We must clear 3474 * B_CACHE if these pages are not valid for the 3475 * range covered by the buffer. 3476 */ 3477 3478 obj = bp->b_bufobj->bo_object; 3479 3480 VM_OBJECT_WLOCK(obj); 3481 while (bp->b_npages < desiredpages) { 3482 vm_page_t m; 3483 3484 /* 3485 * We must allocate system pages since blocking 3486 * here could interfere with paging I/O, no 3487 * matter which process we are. 3488 * 3489 * We can only test VPO_BUSY here. Blocking on 3490 * m->busy might lead to a deadlock: 3491 * vm_fault->getpages->cluster_read->allocbuf 3492 * Thus, we specify VM_ALLOC_IGN_SBUSY. 3493 */ 3494 m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) + 3495 bp->b_npages, VM_ALLOC_NOBUSY | 3496 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED | 3497 VM_ALLOC_RETRY | VM_ALLOC_IGN_SBUSY | 3498 VM_ALLOC_COUNT(desiredpages - bp->b_npages)); 3499 if (m->valid == 0) 3500 bp->b_flags &= ~B_CACHE; 3501 bp->b_pages[bp->b_npages] = m; 3502 ++bp->b_npages; 3503 } 3504 3505 /* 3506 * Step 2. We've loaded the pages into the buffer, 3507 * we have to figure out if we can still have B_CACHE 3508 * set. Note that B_CACHE is set according to the 3509 * byte-granular range ( bcount and size ), new the 3510 * aligned range ( newbsize ). 3511 * 3512 * The VM test is against m->valid, which is DEV_BSIZE 3513 * aligned. Needless to say, the validity of the data 3514 * needs to also be DEV_BSIZE aligned. Note that this 3515 * fails with NFS if the server or some other client 3516 * extends the file's EOF. If our buffer is resized, 3517 * B_CACHE may remain set! XXX 3518 */ 3519 3520 toff = bp->b_bcount; 3521 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 3522 3523 while ((bp->b_flags & B_CACHE) && toff < size) { 3524 vm_pindex_t pi; 3525 3526 if (tinc > (size - toff)) 3527 tinc = size - toff; 3528 3529 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 3530 PAGE_SHIFT; 3531 3532 vfs_buf_test_cache( 3533 bp, 3534 bp->b_offset, 3535 toff, 3536 tinc, 3537 bp->b_pages[pi] 3538 ); 3539 toff += tinc; 3540 tinc = PAGE_SIZE; 3541 } 3542 VM_OBJECT_WUNLOCK(obj); 3543 3544 /* 3545 * Step 3, fixup the KVM pmap. 3546 */ 3547 if ((bp->b_flags & B_UNMAPPED) == 0) 3548 bpmap_qenter(bp); 3549 else 3550 BUF_CHECK_UNMAPPED(bp); 3551 } 3552 } 3553 if (newbsize < bp->b_bufsize) 3554 bufspacewakeup(); 3555 bp->b_bufsize = newbsize; /* actual buffer allocation */ 3556 bp->b_bcount = size; /* requested buffer size */ 3557 return 1; 3558 } 3559 3560 extern int inflight_transient_maps; 3561 3562 void 3563 biodone(struct bio *bp) 3564 { 3565 struct mtx *mtxp; 3566 void (*done)(struct bio *); 3567 vm_offset_t start, end; 3568 int transient; 3569 3570 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3571 mtx_lock(mtxp); 3572 bp->bio_flags |= BIO_DONE; 3573 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) { 3574 start = trunc_page((vm_offset_t)bp->bio_data); 3575 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length); 3576 transient = 1; 3577 } else { 3578 transient = 0; 3579 start = end = 0; 3580 } 3581 done = bp->bio_done; 3582 if (done == NULL) 3583 wakeup(bp); 3584 mtx_unlock(mtxp); 3585 if (done != NULL) 3586 done(bp); 3587 if (transient) { 3588 pmap_qremove(start, OFF_TO_IDX(end - start)); 3589 vmem_free(transient_arena, start, end - start); 3590 atomic_add_int(&inflight_transient_maps, -1); 3591 } 3592 } 3593 3594 /* 3595 * Wait for a BIO to finish. 3596 * 3597 * XXX: resort to a timeout for now. The optimal locking (if any) for this 3598 * case is not yet clear. 3599 */ 3600 int 3601 biowait(struct bio *bp, const char *wchan) 3602 { 3603 struct mtx *mtxp; 3604 3605 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3606 mtx_lock(mtxp); 3607 while ((bp->bio_flags & BIO_DONE) == 0) 3608 msleep(bp, mtxp, PRIBIO, wchan, hz / 10); 3609 mtx_unlock(mtxp); 3610 if (bp->bio_error != 0) 3611 return (bp->bio_error); 3612 if (!(bp->bio_flags & BIO_ERROR)) 3613 return (0); 3614 return (EIO); 3615 } 3616 3617 void 3618 biofinish(struct bio *bp, struct devstat *stat, int error) 3619 { 3620 3621 if (error) { 3622 bp->bio_error = error; 3623 bp->bio_flags |= BIO_ERROR; 3624 } 3625 if (stat != NULL) 3626 devstat_end_transaction_bio(stat, bp); 3627 biodone(bp); 3628 } 3629 3630 /* 3631 * bufwait: 3632 * 3633 * Wait for buffer I/O completion, returning error status. The buffer 3634 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3635 * error and cleared. 3636 */ 3637 int 3638 bufwait(struct buf *bp) 3639 { 3640 if (bp->b_iocmd == BIO_READ) 3641 bwait(bp, PRIBIO, "biord"); 3642 else 3643 bwait(bp, PRIBIO, "biowr"); 3644 if (bp->b_flags & B_EINTR) { 3645 bp->b_flags &= ~B_EINTR; 3646 return (EINTR); 3647 } 3648 if (bp->b_ioflags & BIO_ERROR) { 3649 return (bp->b_error ? bp->b_error : EIO); 3650 } else { 3651 return (0); 3652 } 3653 } 3654 3655 /* 3656 * Call back function from struct bio back up to struct buf. 3657 */ 3658 static void 3659 bufdonebio(struct bio *bip) 3660 { 3661 struct buf *bp; 3662 3663 bp = bip->bio_caller2; 3664 bp->b_resid = bp->b_bcount - bip->bio_completed; 3665 bp->b_resid = bip->bio_resid; /* XXX: remove */ 3666 bp->b_ioflags = bip->bio_flags; 3667 bp->b_error = bip->bio_error; 3668 if (bp->b_error) 3669 bp->b_ioflags |= BIO_ERROR; 3670 bufdone(bp); 3671 g_destroy_bio(bip); 3672 } 3673 3674 void 3675 dev_strategy(struct cdev *dev, struct buf *bp) 3676 { 3677 struct cdevsw *csw; 3678 int ref; 3679 3680 KASSERT(dev->si_refcount > 0, 3681 ("dev_strategy on un-referenced struct cdev *(%s) %p", 3682 devtoname(dev), dev)); 3683 3684 csw = dev_refthread(dev, &ref); 3685 dev_strategy_csw(dev, csw, bp); 3686 dev_relthread(dev, ref); 3687 } 3688 3689 void 3690 dev_strategy_csw(struct cdev *dev, struct cdevsw *csw, struct buf *bp) 3691 { 3692 struct bio *bip; 3693 3694 KASSERT(bp->b_iocmd == BIO_READ || bp->b_iocmd == BIO_WRITE, 3695 ("b_iocmd botch")); 3696 KASSERT(((dev->si_flags & SI_ETERNAL) != 0 && csw != NULL) || 3697 dev->si_threadcount > 0, 3698 ("dev_strategy_csw threadcount cdev *(%s) %p", devtoname(dev), 3699 dev)); 3700 if (csw == NULL) { 3701 bp->b_error = ENXIO; 3702 bp->b_ioflags = BIO_ERROR; 3703 bufdone(bp); 3704 return; 3705 } 3706 for (;;) { 3707 bip = g_new_bio(); 3708 if (bip != NULL) 3709 break; 3710 /* Try again later */ 3711 tsleep(&bp, PRIBIO, "dev_strat", hz/10); 3712 } 3713 bip->bio_cmd = bp->b_iocmd; 3714 bip->bio_offset = bp->b_iooffset; 3715 bip->bio_length = bp->b_bcount; 3716 bip->bio_bcount = bp->b_bcount; /* XXX: remove */ 3717 bdata2bio(bp, bip); 3718 bip->bio_done = bufdonebio; 3719 bip->bio_caller2 = bp; 3720 bip->bio_dev = dev; 3721 (*csw->d_strategy)(bip); 3722 } 3723 3724 /* 3725 * bufdone: 3726 * 3727 * Finish I/O on a buffer, optionally calling a completion function. 3728 * This is usually called from an interrupt so process blocking is 3729 * not allowed. 3730 * 3731 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3732 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3733 * assuming B_INVAL is clear. 3734 * 3735 * For the VMIO case, we set B_CACHE if the op was a read and no 3736 * read error occured, or if the op was a write. B_CACHE is never 3737 * set if the buffer is invalid or otherwise uncacheable. 3738 * 3739 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3740 * initiator to leave B_INVAL set to brelse the buffer out of existance 3741 * in the biodone routine. 3742 */ 3743 void 3744 bufdone(struct buf *bp) 3745 { 3746 struct bufobj *dropobj; 3747 void (*biodone)(struct buf *); 3748 3749 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 3750 dropobj = NULL; 3751 3752 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 3753 BUF_ASSERT_HELD(bp); 3754 3755 runningbufwakeup(bp); 3756 if (bp->b_iocmd == BIO_WRITE) 3757 dropobj = bp->b_bufobj; 3758 /* call optional completion function if requested */ 3759 if (bp->b_iodone != NULL) { 3760 biodone = bp->b_iodone; 3761 bp->b_iodone = NULL; 3762 (*biodone) (bp); 3763 if (dropobj) 3764 bufobj_wdrop(dropobj); 3765 return; 3766 } 3767 3768 bufdone_finish(bp); 3769 3770 if (dropobj) 3771 bufobj_wdrop(dropobj); 3772 } 3773 3774 void 3775 bufdone_finish(struct buf *bp) 3776 { 3777 BUF_ASSERT_HELD(bp); 3778 3779 if (!LIST_EMPTY(&bp->b_dep)) 3780 buf_complete(bp); 3781 3782 if (bp->b_flags & B_VMIO) { 3783 vm_ooffset_t foff; 3784 vm_page_t m; 3785 vm_object_t obj; 3786 struct vnode *vp; 3787 int bogus, i, iosize; 3788 3789 obj = bp->b_bufobj->bo_object; 3790 KASSERT(obj->paging_in_progress >= bp->b_npages, 3791 ("biodone_finish: paging in progress(%d) < b_npages(%d)", 3792 obj->paging_in_progress, bp->b_npages)); 3793 3794 vp = bp->b_vp; 3795 KASSERT(vp->v_holdcnt > 0, 3796 ("biodone_finish: vnode %p has zero hold count", vp)); 3797 KASSERT(vp->v_object != NULL, 3798 ("biodone_finish: vnode %p has no vm_object", vp)); 3799 3800 foff = bp->b_offset; 3801 KASSERT(bp->b_offset != NOOFFSET, 3802 ("biodone_finish: bp %p has no buffer offset", bp)); 3803 3804 /* 3805 * Set B_CACHE if the op was a normal read and no error 3806 * occured. B_CACHE is set for writes in the b*write() 3807 * routines. 3808 */ 3809 iosize = bp->b_bcount - bp->b_resid; 3810 if (bp->b_iocmd == BIO_READ && 3811 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 3812 !(bp->b_ioflags & BIO_ERROR)) { 3813 bp->b_flags |= B_CACHE; 3814 } 3815 bogus = 0; 3816 VM_OBJECT_WLOCK(obj); 3817 for (i = 0; i < bp->b_npages; i++) { 3818 int bogusflag = 0; 3819 int resid; 3820 3821 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 3822 if (resid > iosize) 3823 resid = iosize; 3824 3825 /* 3826 * cleanup bogus pages, restoring the originals 3827 */ 3828 m = bp->b_pages[i]; 3829 if (m == bogus_page) { 3830 bogus = bogusflag = 1; 3831 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3832 if (m == NULL) 3833 panic("biodone: page disappeared!"); 3834 bp->b_pages[i] = m; 3835 } 3836 KASSERT(OFF_TO_IDX(foff) == m->pindex, 3837 ("biodone_finish: foff(%jd)/pindex(%ju) mismatch", 3838 (intmax_t)foff, (uintmax_t)m->pindex)); 3839 3840 /* 3841 * In the write case, the valid and clean bits are 3842 * already changed correctly ( see bdwrite() ), so we 3843 * only need to do this here in the read case. 3844 */ 3845 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 3846 KASSERT((m->dirty & vm_page_bits(foff & 3847 PAGE_MASK, resid)) == 0, ("bufdone_finish:" 3848 " page %p has unexpected dirty bits", m)); 3849 vfs_page_set_valid(bp, foff, m); 3850 } 3851 3852 vm_page_io_finish(m); 3853 vm_object_pip_subtract(obj, 1); 3854 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3855 iosize -= resid; 3856 } 3857 vm_object_pip_wakeupn(obj, 0); 3858 VM_OBJECT_WUNLOCK(obj); 3859 if (bogus && (bp->b_flags & B_UNMAPPED) == 0) { 3860 BUF_CHECK_MAPPED(bp); 3861 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3862 bp->b_pages, bp->b_npages); 3863 } 3864 } 3865 3866 /* 3867 * For asynchronous completions, release the buffer now. The brelse 3868 * will do a wakeup there if necessary - so no need to do a wakeup 3869 * here in the async case. The sync case always needs to do a wakeup. 3870 */ 3871 3872 if (bp->b_flags & B_ASYNC) { 3873 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 3874 brelse(bp); 3875 else 3876 bqrelse(bp); 3877 } else 3878 bdone(bp); 3879 } 3880 3881 /* 3882 * This routine is called in lieu of iodone in the case of 3883 * incomplete I/O. This keeps the busy status for pages 3884 * consistant. 3885 */ 3886 void 3887 vfs_unbusy_pages(struct buf *bp) 3888 { 3889 int i; 3890 vm_object_t obj; 3891 vm_page_t m; 3892 3893 runningbufwakeup(bp); 3894 if (!(bp->b_flags & B_VMIO)) 3895 return; 3896 3897 obj = bp->b_bufobj->bo_object; 3898 VM_OBJECT_WLOCK(obj); 3899 for (i = 0; i < bp->b_npages; i++) { 3900 m = bp->b_pages[i]; 3901 if (m == bogus_page) { 3902 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 3903 if (!m) 3904 panic("vfs_unbusy_pages: page missing\n"); 3905 bp->b_pages[i] = m; 3906 if ((bp->b_flags & B_UNMAPPED) == 0) { 3907 BUF_CHECK_MAPPED(bp); 3908 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3909 bp->b_pages, bp->b_npages); 3910 } else 3911 BUF_CHECK_UNMAPPED(bp); 3912 } 3913 vm_object_pip_subtract(obj, 1); 3914 vm_page_io_finish(m); 3915 } 3916 vm_object_pip_wakeupn(obj, 0); 3917 VM_OBJECT_WUNLOCK(obj); 3918 } 3919 3920 /* 3921 * vfs_page_set_valid: 3922 * 3923 * Set the valid bits in a page based on the supplied offset. The 3924 * range is restricted to the buffer's size. 3925 * 3926 * This routine is typically called after a read completes. 3927 */ 3928 static void 3929 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3930 { 3931 vm_ooffset_t eoff; 3932 3933 /* 3934 * Compute the end offset, eoff, such that [off, eoff) does not span a 3935 * page boundary and eoff is not greater than the end of the buffer. 3936 * The end of the buffer, in this case, is our file EOF, not the 3937 * allocation size of the buffer. 3938 */ 3939 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 3940 if (eoff > bp->b_offset + bp->b_bcount) 3941 eoff = bp->b_offset + bp->b_bcount; 3942 3943 /* 3944 * Set valid range. This is typically the entire buffer and thus the 3945 * entire page. 3946 */ 3947 if (eoff > off) 3948 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off); 3949 } 3950 3951 /* 3952 * vfs_page_set_validclean: 3953 * 3954 * Set the valid bits and clear the dirty bits in a page based on the 3955 * supplied offset. The range is restricted to the buffer's size. 3956 */ 3957 static void 3958 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3959 { 3960 vm_ooffset_t soff, eoff; 3961 3962 /* 3963 * Start and end offsets in buffer. eoff - soff may not cross a 3964 * page boundry or cross the end of the buffer. The end of the 3965 * buffer, in this case, is our file EOF, not the allocation size 3966 * of the buffer. 3967 */ 3968 soff = off; 3969 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3970 if (eoff > bp->b_offset + bp->b_bcount) 3971 eoff = bp->b_offset + bp->b_bcount; 3972 3973 /* 3974 * Set valid range. This is typically the entire buffer and thus the 3975 * entire page. 3976 */ 3977 if (eoff > soff) { 3978 vm_page_set_validclean( 3979 m, 3980 (vm_offset_t) (soff & PAGE_MASK), 3981 (vm_offset_t) (eoff - soff) 3982 ); 3983 } 3984 } 3985 3986 /* 3987 * Ensure that all buffer pages are not busied by VPO_BUSY flag. If 3988 * any page is busy, drain the flag. 3989 */ 3990 static void 3991 vfs_drain_busy_pages(struct buf *bp) 3992 { 3993 vm_page_t m; 3994 int i, last_busied; 3995 3996 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object); 3997 last_busied = 0; 3998 for (i = 0; i < bp->b_npages; i++) { 3999 m = bp->b_pages[i]; 4000 if ((m->oflags & VPO_BUSY) != 0) { 4001 for (; last_busied < i; last_busied++) 4002 vm_page_busy(bp->b_pages[last_busied]); 4003 while ((m->oflags & VPO_BUSY) != 0) 4004 vm_page_sleep(m, "vbpage"); 4005 } 4006 } 4007 for (i = 0; i < last_busied; i++) 4008 vm_page_wakeup(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 VPO_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_io_start(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 (p->busy != 0) 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 %d %d", bp, bip->bio_ma_offset, 4489 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