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/racct.h> 65 #include <sys/resourcevar.h> 66 #include <sys/rwlock.h> 67 #include <sys/smp.h> 68 #include <sys/sysctl.h> 69 #include <sys/sysproto.h> 70 #include <sys/vmem.h> 71 #include <sys/vmmeter.h> 72 #include <sys/vnode.h> 73 #include <sys/watchdog.h> 74 #include <geom/geom.h> 75 #include <vm/vm.h> 76 #include <vm/vm_param.h> 77 #include <vm/vm_kern.h> 78 #include <vm/vm_pageout.h> 79 #include <vm/vm_page.h> 80 #include <vm/vm_object.h> 81 #include <vm/vm_extern.h> 82 #include <vm/vm_map.h> 83 #include <vm/swap_pager.h> 84 #include "opt_compat.h" 85 #include "opt_swap.h" 86 87 static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer"); 88 89 struct bio_ops bioops; /* I/O operation notification */ 90 91 struct buf_ops buf_ops_bio = { 92 .bop_name = "buf_ops_bio", 93 .bop_write = bufwrite, 94 .bop_strategy = bufstrategy, 95 .bop_sync = bufsync, 96 .bop_bdflush = bufbdflush, 97 }; 98 99 static struct buf *buf; /* buffer header pool */ 100 extern struct buf *swbuf; /* Swap buffer header pool. */ 101 caddr_t unmapped_buf; 102 103 /* Used below and for softdep flushing threads in ufs/ffs/ffs_softdep.c */ 104 struct proc *bufdaemonproc; 105 struct proc *bufspacedaemonproc; 106 107 static int inmem(struct vnode *vp, daddr_t blkno); 108 static void vm_hold_free_pages(struct buf *bp, int newbsize); 109 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from, 110 vm_offset_t to); 111 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m); 112 static void vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, 113 vm_page_t m); 114 static void vfs_clean_pages_dirty_buf(struct buf *bp); 115 static void vfs_setdirty_locked_object(struct buf *bp); 116 static void vfs_vmio_invalidate(struct buf *bp); 117 static void vfs_vmio_truncate(struct buf *bp, int npages); 118 static void vfs_vmio_extend(struct buf *bp, int npages, int size); 119 static int vfs_bio_clcheck(struct vnode *vp, int size, 120 daddr_t lblkno, daddr_t blkno); 121 static int buf_flush(struct vnode *vp, int); 122 static int buf_recycle(bool); 123 static int buf_scan(bool); 124 static int flushbufqueues(struct vnode *, int, int); 125 static void buf_daemon(void); 126 static void bremfreel(struct buf *bp); 127 static __inline void bd_wakeup(void); 128 static int sysctl_runningspace(SYSCTL_HANDLER_ARGS); 129 static void bufkva_reclaim(vmem_t *, int); 130 static void bufkva_free(struct buf *); 131 static int buf_import(void *, void **, int, int); 132 static void buf_release(void *, void **, int); 133 134 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 135 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 136 static int sysctl_bufspace(SYSCTL_HANDLER_ARGS); 137 #endif 138 139 int vmiodirenable = TRUE; 140 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, 141 "Use the VM system for directory writes"); 142 long runningbufspace; 143 SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 144 "Amount of presently outstanding async buffer io"); 145 static long bufspace; 146 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 147 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 148 SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD, 149 &bufspace, 0, sysctl_bufspace, "L", "Virtual memory used for buffers"); 150 #else 151 SYSCTL_LONG(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, 152 "Physical memory used for buffers"); 153 #endif 154 static long bufkvaspace; 155 SYSCTL_LONG(_vfs, OID_AUTO, bufkvaspace, CTLFLAG_RD, &bufkvaspace, 0, 156 "Kernel virtual memory used for buffers"); 157 static long maxbufspace; 158 SYSCTL_LONG(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RW, &maxbufspace, 0, 159 "Maximum allowed value of bufspace (including metadata)"); 160 static long bufmallocspace; 161 SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 162 "Amount of malloced memory for buffers"); 163 static long maxbufmallocspace; 164 SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 165 0, "Maximum amount of malloced memory for buffers"); 166 static long lobufspace; 167 SYSCTL_LONG(_vfs, OID_AUTO, lobufspace, CTLFLAG_RW, &lobufspace, 0, 168 "Minimum amount of buffers we want to have"); 169 long hibufspace; 170 SYSCTL_LONG(_vfs, OID_AUTO, hibufspace, CTLFLAG_RW, &hibufspace, 0, 171 "Maximum allowed value of bufspace (excluding metadata)"); 172 long bufspacethresh; 173 SYSCTL_LONG(_vfs, OID_AUTO, bufspacethresh, CTLFLAG_RW, &bufspacethresh, 174 0, "Bufspace consumed before waking the daemon to free some"); 175 static int buffreekvacnt; 176 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0, 177 "Number of times we have freed the KVA space from some buffer"); 178 static int bufdefragcnt; 179 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0, 180 "Number of times we have had to repeat buffer allocation to defragment"); 181 static long lorunningspace; 182 SYSCTL_PROC(_vfs, OID_AUTO, lorunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE | 183 CTLFLAG_RW, &lorunningspace, 0, sysctl_runningspace, "L", 184 "Minimum preferred space used for in-progress I/O"); 185 static long hirunningspace; 186 SYSCTL_PROC(_vfs, OID_AUTO, hirunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE | 187 CTLFLAG_RW, &hirunningspace, 0, sysctl_runningspace, "L", 188 "Maximum amount of space to use for in-progress I/O"); 189 int dirtybufferflushes; 190 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes, 191 0, "Number of bdwrite to bawrite conversions to limit dirty buffers"); 192 int bdwriteskip; 193 SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip, 194 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk"); 195 int altbufferflushes; 196 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes, 197 0, "Number of fsync flushes to limit dirty buffers"); 198 static int recursiveflushes; 199 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes, 200 0, "Number of flushes skipped due to being recursive"); 201 static int numdirtybuffers; 202 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0, 203 "Number of buffers that are dirty (has unwritten changes) at the moment"); 204 static int lodirtybuffers; 205 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0, 206 "How many buffers we want to have free before bufdaemon can sleep"); 207 static int hidirtybuffers; 208 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0, 209 "When the number of dirty buffers is considered severe"); 210 int dirtybufthresh; 211 SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh, 212 0, "Number of bdwrite to bawrite conversions to clear dirty buffers"); 213 static int numfreebuffers; 214 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, 215 "Number of free buffers"); 216 static int lofreebuffers; 217 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0, 218 "Target number of free buffers"); 219 static int hifreebuffers; 220 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0, 221 "Threshold for clean buffer recycling"); 222 static int getnewbufcalls; 223 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0, 224 "Number of calls to getnewbuf"); 225 static int getnewbufrestarts; 226 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0, 227 "Number of times getnewbuf has had to restart a buffer aquisition"); 228 static int mappingrestarts; 229 SYSCTL_INT(_vfs, OID_AUTO, mappingrestarts, CTLFLAG_RW, &mappingrestarts, 0, 230 "Number of times getblk has had to restart a buffer mapping for " 231 "unmapped buffer"); 232 static int numbufallocfails; 233 SYSCTL_INT(_vfs, OID_AUTO, numbufallocfails, CTLFLAG_RW, &numbufallocfails, 0, 234 "Number of times buffer allocations failed"); 235 static int flushbufqtarget = 100; 236 SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0, 237 "Amount of work to do in flushbufqueues when helping bufdaemon"); 238 static long notbufdflushes; 239 SYSCTL_LONG(_vfs, OID_AUTO, notbufdflushes, CTLFLAG_RD, ¬bufdflushes, 0, 240 "Number of dirty buffer flushes done by the bufdaemon helpers"); 241 static long barrierwrites; 242 SYSCTL_LONG(_vfs, OID_AUTO, barrierwrites, CTLFLAG_RW, &barrierwrites, 0, 243 "Number of barrier writes"); 244 SYSCTL_INT(_vfs, OID_AUTO, unmapped_buf_allowed, CTLFLAG_RD, 245 &unmapped_buf_allowed, 0, 246 "Permit the use of the unmapped i/o"); 247 248 /* 249 * This lock synchronizes access to bd_request. 250 */ 251 static struct mtx_padalign bdlock; 252 253 /* 254 * This lock protects the runningbufreq and synchronizes runningbufwakeup and 255 * waitrunningbufspace(). 256 */ 257 static struct mtx_padalign rbreqlock; 258 259 /* 260 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it. 261 */ 262 static struct rwlock_padalign nblock; 263 264 /* 265 * Lock that protects bdirtywait. 266 */ 267 static struct mtx_padalign bdirtylock; 268 269 /* 270 * Wakeup point for bufdaemon, as well as indicator of whether it is already 271 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it 272 * is idling. 273 */ 274 static int bd_request; 275 276 /* 277 * Request/wakeup point for the bufspace daemon. 278 */ 279 static int bufspace_request; 280 281 /* 282 * Request for the buf daemon to write more buffers than is indicated by 283 * lodirtybuf. This may be necessary to push out excess dependencies or 284 * defragment the address space where a simple count of the number of dirty 285 * buffers is insufficient to characterize the demand for flushing them. 286 */ 287 static int bd_speedupreq; 288 289 /* 290 * bogus page -- for I/O to/from partially complete buffers 291 * this is a temporary solution to the problem, but it is not 292 * really that bad. it would be better to split the buffer 293 * for input in the case of buffers partially already in memory, 294 * but the code is intricate enough already. 295 */ 296 vm_page_t bogus_page; 297 298 /* 299 * Synchronization (sleep/wakeup) variable for active buffer space requests. 300 * Set when wait starts, cleared prior to wakeup(). 301 * Used in runningbufwakeup() and waitrunningbufspace(). 302 */ 303 static int runningbufreq; 304 305 /* 306 * Synchronization (sleep/wakeup) variable for buffer requests. 307 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done 308 * by and/or. 309 * Used in numdirtywakeup(), bufspace_wakeup(), bwillwrite(), 310 * getnewbuf(), and getblk(). 311 */ 312 static volatile int needsbuffer; 313 314 /* 315 * Synchronization for bwillwrite() waiters. 316 */ 317 static int bdirtywait; 318 319 /* 320 * Definitions for the buffer free lists. 321 */ 322 #define QUEUE_NONE 0 /* on no queue */ 323 #define QUEUE_EMPTY 1 /* empty buffer headers */ 324 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */ 325 #define QUEUE_CLEAN 3 /* non-B_DELWRI buffers */ 326 #define QUEUE_SENTINEL 1024 /* not an queue index, but mark for sentinel */ 327 328 /* Maximum number of clean buffer queues. */ 329 #define CLEAN_QUEUES 16 330 331 /* Configured number of clean queues. */ 332 static int clean_queues; 333 334 /* Maximum number of buffer queues. */ 335 #define BUFFER_QUEUES (QUEUE_CLEAN + CLEAN_QUEUES) 336 337 /* Queues for free buffers with various properties */ 338 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } }; 339 #ifdef INVARIANTS 340 static int bq_len[BUFFER_QUEUES]; 341 #endif 342 343 /* 344 * Lock for each bufqueue 345 */ 346 static struct mtx_padalign bqlocks[BUFFER_QUEUES]; 347 348 /* 349 * per-cpu empty buffer cache. 350 */ 351 uma_zone_t buf_zone; 352 353 /* 354 * Single global constant for BUF_WMESG, to avoid getting multiple references. 355 * buf_wmesg is referred from macros. 356 */ 357 const char *buf_wmesg = BUF_WMESG; 358 359 static int 360 sysctl_runningspace(SYSCTL_HANDLER_ARGS) 361 { 362 long value; 363 int error; 364 365 value = *(long *)arg1; 366 error = sysctl_handle_long(oidp, &value, 0, req); 367 if (error != 0 || req->newptr == NULL) 368 return (error); 369 mtx_lock(&rbreqlock); 370 if (arg1 == &hirunningspace) { 371 if (value < lorunningspace) 372 error = EINVAL; 373 else 374 hirunningspace = value; 375 } else { 376 KASSERT(arg1 == &lorunningspace, 377 ("%s: unknown arg1", __func__)); 378 if (value > hirunningspace) 379 error = EINVAL; 380 else 381 lorunningspace = value; 382 } 383 mtx_unlock(&rbreqlock); 384 return (error); 385 } 386 387 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 388 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 389 static int 390 sysctl_bufspace(SYSCTL_HANDLER_ARGS) 391 { 392 long lvalue; 393 int ivalue; 394 395 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long)) 396 return (sysctl_handle_long(oidp, arg1, arg2, req)); 397 lvalue = *(long *)arg1; 398 if (lvalue > INT_MAX) 399 /* On overflow, still write out a long to trigger ENOMEM. */ 400 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 401 ivalue = lvalue; 402 return (sysctl_handle_int(oidp, &ivalue, 0, req)); 403 } 404 #endif 405 406 static int 407 bqcleanq(void) 408 { 409 static int nextq; 410 411 return ((atomic_fetchadd_int(&nextq, 1) % clean_queues) + QUEUE_CLEAN); 412 } 413 414 static int 415 bqisclean(int qindex) 416 { 417 418 return (qindex >= QUEUE_CLEAN && qindex < QUEUE_CLEAN + CLEAN_QUEUES); 419 } 420 421 /* 422 * bqlock: 423 * 424 * Return the appropriate queue lock based on the index. 425 */ 426 static inline struct mtx * 427 bqlock(int qindex) 428 { 429 430 return (struct mtx *)&bqlocks[qindex]; 431 } 432 433 /* 434 * bdirtywakeup: 435 * 436 * Wakeup any bwillwrite() waiters. 437 */ 438 static void 439 bdirtywakeup(void) 440 { 441 mtx_lock(&bdirtylock); 442 if (bdirtywait) { 443 bdirtywait = 0; 444 wakeup(&bdirtywait); 445 } 446 mtx_unlock(&bdirtylock); 447 } 448 449 /* 450 * bdirtysub: 451 * 452 * Decrement the numdirtybuffers count by one and wakeup any 453 * threads blocked in bwillwrite(). 454 */ 455 static void 456 bdirtysub(void) 457 { 458 459 if (atomic_fetchadd_int(&numdirtybuffers, -1) == 460 (lodirtybuffers + hidirtybuffers) / 2) 461 bdirtywakeup(); 462 } 463 464 /* 465 * bdirtyadd: 466 * 467 * Increment the numdirtybuffers count by one and wakeup the buf 468 * daemon if needed. 469 */ 470 static void 471 bdirtyadd(void) 472 { 473 474 /* 475 * Only do the wakeup once as we cross the boundary. The 476 * buf daemon will keep running until the condition clears. 477 */ 478 if (atomic_fetchadd_int(&numdirtybuffers, 1) == 479 (lodirtybuffers + hidirtybuffers) / 2) 480 bd_wakeup(); 481 } 482 483 /* 484 * bufspace_wakeup: 485 * 486 * Called when buffer space is potentially available for recovery. 487 * getnewbuf() will block on this flag when it is unable to free 488 * sufficient buffer space. Buffer space becomes recoverable when 489 * bp's get placed back in the queues. 490 */ 491 static void 492 bufspace_wakeup(void) 493 { 494 495 /* 496 * If someone is waiting for bufspace, wake them up. 497 * 498 * Since needsbuffer is set prior to doing an additional queue 499 * scan it is safe to check for the flag prior to acquiring the 500 * lock. The thread that is preparing to scan again before 501 * blocking would discover the buf we released. 502 */ 503 if (needsbuffer) { 504 rw_rlock(&nblock); 505 if (atomic_cmpset_int(&needsbuffer, 1, 0) == 1) 506 wakeup(__DEVOLATILE(void *, &needsbuffer)); 507 rw_runlock(&nblock); 508 } 509 } 510 511 /* 512 * bufspace_daemonwakeup: 513 * 514 * Wakeup the daemon responsible for freeing clean bufs. 515 */ 516 static void 517 bufspace_daemonwakeup(void) 518 { 519 rw_rlock(&nblock); 520 if (bufspace_request == 0) { 521 bufspace_request = 1; 522 wakeup(&bufspace_request); 523 } 524 rw_runlock(&nblock); 525 } 526 527 /* 528 * bufspace_adjust: 529 * 530 * Adjust the reported bufspace for a KVA managed buffer, possibly 531 * waking any waiters. 532 */ 533 static void 534 bufspace_adjust(struct buf *bp, int bufsize) 535 { 536 long space; 537 int diff; 538 539 KASSERT((bp->b_flags & B_MALLOC) == 0, 540 ("bufspace_adjust: malloc buf %p", bp)); 541 diff = bufsize - bp->b_bufsize; 542 if (diff < 0) { 543 atomic_subtract_long(&bufspace, -diff); 544 bufspace_wakeup(); 545 } else { 546 space = atomic_fetchadd_long(&bufspace, diff); 547 /* Wake up the daemon on the transition. */ 548 if (space < bufspacethresh && space + diff >= bufspacethresh) 549 bufspace_daemonwakeup(); 550 } 551 bp->b_bufsize = bufsize; 552 } 553 554 /* 555 * bufspace_reserve: 556 * 557 * Reserve bufspace before calling allocbuf(). metadata has a 558 * different space limit than data. 559 */ 560 static int 561 bufspace_reserve(int size, bool metadata) 562 { 563 long limit; 564 long space; 565 566 if (metadata) 567 limit = maxbufspace; 568 else 569 limit = hibufspace; 570 do { 571 space = bufspace; 572 if (space + size > limit) 573 return (ENOSPC); 574 } while (atomic_cmpset_long(&bufspace, space, space + size) == 0); 575 576 /* Wake up the daemon on the transition. */ 577 if (space < bufspacethresh && space + size >= bufspacethresh) 578 bufspace_daemonwakeup(); 579 580 return (0); 581 } 582 583 /* 584 * bufspace_release: 585 * 586 * Release reserved bufspace after bufspace_adjust() has consumed it. 587 */ 588 static void 589 bufspace_release(int size) 590 { 591 atomic_subtract_long(&bufspace, size); 592 bufspace_wakeup(); 593 } 594 595 /* 596 * bufspace_wait: 597 * 598 * Wait for bufspace, acting as the buf daemon if a locked vnode is 599 * supplied. needsbuffer must be set in a safe fashion prior to 600 * polling for space. The operation must be re-tried on return. 601 */ 602 static void 603 bufspace_wait(struct vnode *vp, int gbflags, int slpflag, int slptimeo) 604 { 605 struct thread *td; 606 int error, fl, norunbuf; 607 608 if ((gbflags & GB_NOWAIT_BD) != 0) 609 return; 610 611 td = curthread; 612 rw_wlock(&nblock); 613 while (needsbuffer != 0) { 614 if (vp != NULL && vp->v_type != VCHR && 615 (td->td_pflags & TDP_BUFNEED) == 0) { 616 rw_wunlock(&nblock); 617 /* 618 * getblk() is called with a vnode locked, and 619 * some majority of the dirty buffers may as 620 * well belong to the vnode. Flushing the 621 * buffers there would make a progress that 622 * cannot be achieved by the buf_daemon, that 623 * cannot lock the vnode. 624 */ 625 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) | 626 (td->td_pflags & TDP_NORUNNINGBUF); 627 628 /* 629 * Play bufdaemon. The getnewbuf() function 630 * may be called while the thread owns lock 631 * for another dirty buffer for the same 632 * vnode, which makes it impossible to use 633 * VOP_FSYNC() there, due to the buffer lock 634 * recursion. 635 */ 636 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF; 637 fl = buf_flush(vp, flushbufqtarget); 638 td->td_pflags &= norunbuf; 639 rw_wlock(&nblock); 640 if (fl != 0) 641 continue; 642 if (needsbuffer == 0) 643 break; 644 } 645 error = rw_sleep(__DEVOLATILE(void *, &needsbuffer), &nblock, 646 (PRIBIO + 4) | slpflag, "newbuf", slptimeo); 647 if (error != 0) 648 break; 649 } 650 rw_wunlock(&nblock); 651 } 652 653 654 /* 655 * bufspace_daemon: 656 * 657 * buffer space management daemon. Tries to maintain some marginal 658 * amount of free buffer space so that requesting processes neither 659 * block nor work to reclaim buffers. 660 */ 661 static void 662 bufspace_daemon(void) 663 { 664 for (;;) { 665 kproc_suspend_check(bufspacedaemonproc); 666 667 /* 668 * Free buffers from the clean queue until we meet our 669 * targets. 670 * 671 * Theory of operation: The buffer cache is most efficient 672 * when some free buffer headers and space are always 673 * available to getnewbuf(). This daemon attempts to prevent 674 * the excessive blocking and synchronization associated 675 * with shortfall. It goes through three phases according 676 * demand: 677 * 678 * 1) The daemon wakes up voluntarily once per-second 679 * during idle periods when the counters are below 680 * the wakeup thresholds (bufspacethresh, lofreebuffers). 681 * 682 * 2) The daemon wakes up as we cross the thresholds 683 * ahead of any potential blocking. This may bounce 684 * slightly according to the rate of consumption and 685 * release. 686 * 687 * 3) The daemon and consumers are starved for working 688 * clean buffers. This is the 'bufspace' sleep below 689 * which will inefficiently trade bufs with bqrelse 690 * until we return to condition 2. 691 */ 692 while (bufspace > lobufspace || 693 numfreebuffers < hifreebuffers) { 694 if (buf_recycle(false) != 0) { 695 atomic_set_int(&needsbuffer, 1); 696 if (buf_recycle(false) != 0) { 697 rw_wlock(&nblock); 698 if (needsbuffer) 699 rw_sleep(__DEVOLATILE(void *, 700 &needsbuffer), &nblock, 701 PRIBIO|PDROP, "bufspace", 702 hz/10); 703 else 704 rw_wunlock(&nblock); 705 } 706 } 707 maybe_yield(); 708 } 709 710 /* 711 * Re-check our limits under the exclusive nblock. 712 */ 713 rw_wlock(&nblock); 714 if (bufspace < bufspacethresh && 715 numfreebuffers > lofreebuffers) { 716 bufspace_request = 0; 717 rw_sleep(&bufspace_request, &nblock, PRIBIO|PDROP, 718 "-", hz); 719 } else 720 rw_wunlock(&nblock); 721 } 722 } 723 724 static struct kproc_desc bufspace_kp = { 725 "bufspacedaemon", 726 bufspace_daemon, 727 &bufspacedaemonproc 728 }; 729 SYSINIT(bufspacedaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, 730 &bufspace_kp); 731 732 /* 733 * bufmallocadjust: 734 * 735 * Adjust the reported bufspace for a malloc managed buffer, possibly 736 * waking any waiters. 737 */ 738 static void 739 bufmallocadjust(struct buf *bp, int bufsize) 740 { 741 int diff; 742 743 KASSERT((bp->b_flags & B_MALLOC) != 0, 744 ("bufmallocadjust: non-malloc buf %p", bp)); 745 diff = bufsize - bp->b_bufsize; 746 if (diff < 0) 747 atomic_subtract_long(&bufmallocspace, -diff); 748 else 749 atomic_add_long(&bufmallocspace, diff); 750 bp->b_bufsize = bufsize; 751 } 752 753 /* 754 * runningwakeup: 755 * 756 * Wake up processes that are waiting on asynchronous writes to fall 757 * below lorunningspace. 758 */ 759 static void 760 runningwakeup(void) 761 { 762 763 mtx_lock(&rbreqlock); 764 if (runningbufreq) { 765 runningbufreq = 0; 766 wakeup(&runningbufreq); 767 } 768 mtx_unlock(&rbreqlock); 769 } 770 771 /* 772 * runningbufwakeup: 773 * 774 * Decrement the outstanding write count according. 775 */ 776 void 777 runningbufwakeup(struct buf *bp) 778 { 779 long space, bspace; 780 781 bspace = bp->b_runningbufspace; 782 if (bspace == 0) 783 return; 784 space = atomic_fetchadd_long(&runningbufspace, -bspace); 785 KASSERT(space >= bspace, ("runningbufspace underflow %ld %ld", 786 space, bspace)); 787 bp->b_runningbufspace = 0; 788 /* 789 * Only acquire the lock and wakeup on the transition from exceeding 790 * the threshold to falling below it. 791 */ 792 if (space < lorunningspace) 793 return; 794 if (space - bspace > lorunningspace) 795 return; 796 runningwakeup(); 797 } 798 799 /* 800 * waitrunningbufspace() 801 * 802 * runningbufspace is a measure of the amount of I/O currently 803 * running. This routine is used in async-write situations to 804 * prevent creating huge backups of pending writes to a device. 805 * Only asynchronous writes are governed by this function. 806 * 807 * This does NOT turn an async write into a sync write. It waits 808 * for earlier writes to complete and generally returns before the 809 * caller's write has reached the device. 810 */ 811 void 812 waitrunningbufspace(void) 813 { 814 815 mtx_lock(&rbreqlock); 816 while (runningbufspace > hirunningspace) { 817 runningbufreq = 1; 818 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 819 } 820 mtx_unlock(&rbreqlock); 821 } 822 823 824 /* 825 * vfs_buf_test_cache: 826 * 827 * Called when a buffer is extended. This function clears the B_CACHE 828 * bit if the newly extended portion of the buffer does not contain 829 * valid data. 830 */ 831 static __inline void 832 vfs_buf_test_cache(struct buf *bp, vm_ooffset_t foff, vm_offset_t off, 833 vm_offset_t size, vm_page_t m) 834 { 835 836 VM_OBJECT_ASSERT_LOCKED(m->object); 837 if (bp->b_flags & B_CACHE) { 838 int base = (foff + off) & PAGE_MASK; 839 if (vm_page_is_valid(m, base, size) == 0) 840 bp->b_flags &= ~B_CACHE; 841 } 842 } 843 844 /* Wake up the buffer daemon if necessary */ 845 static __inline void 846 bd_wakeup(void) 847 { 848 849 mtx_lock(&bdlock); 850 if (bd_request == 0) { 851 bd_request = 1; 852 wakeup(&bd_request); 853 } 854 mtx_unlock(&bdlock); 855 } 856 857 /* 858 * bd_speedup - speedup the buffer cache flushing code 859 */ 860 void 861 bd_speedup(void) 862 { 863 int needwake; 864 865 mtx_lock(&bdlock); 866 needwake = 0; 867 if (bd_speedupreq == 0 || bd_request == 0) 868 needwake = 1; 869 bd_speedupreq = 1; 870 bd_request = 1; 871 if (needwake) 872 wakeup(&bd_request); 873 mtx_unlock(&bdlock); 874 } 875 876 #ifndef NSWBUF_MIN 877 #define NSWBUF_MIN 16 878 #endif 879 880 #ifdef __i386__ 881 #define TRANSIENT_DENOM 5 882 #else 883 #define TRANSIENT_DENOM 10 884 #endif 885 886 /* 887 * Calculating buffer cache scaling values and reserve space for buffer 888 * headers. This is called during low level kernel initialization and 889 * may be called more then once. We CANNOT write to the memory area 890 * being reserved at this time. 891 */ 892 caddr_t 893 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 894 { 895 int tuned_nbuf; 896 long maxbuf, maxbuf_sz, buf_sz, biotmap_sz; 897 898 /* 899 * physmem_est is in pages. Convert it to kilobytes (assumes 900 * PAGE_SIZE is >= 1K) 901 */ 902 physmem_est = physmem_est * (PAGE_SIZE / 1024); 903 904 /* 905 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 906 * For the first 64MB of ram nominally allocate sufficient buffers to 907 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 908 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing 909 * the buffer cache we limit the eventual kva reservation to 910 * maxbcache bytes. 911 * 912 * factor represents the 1/4 x ram conversion. 913 */ 914 if (nbuf == 0) { 915 int factor = 4 * BKVASIZE / 1024; 916 917 nbuf = 50; 918 if (physmem_est > 4096) 919 nbuf += min((physmem_est - 4096) / factor, 920 65536 / factor); 921 if (physmem_est > 65536) 922 nbuf += min((physmem_est - 65536) * 2 / (factor * 5), 923 32 * 1024 * 1024 / (factor * 5)); 924 925 if (maxbcache && nbuf > maxbcache / BKVASIZE) 926 nbuf = maxbcache / BKVASIZE; 927 tuned_nbuf = 1; 928 } else 929 tuned_nbuf = 0; 930 931 /* XXX Avoid unsigned long overflows later on with maxbufspace. */ 932 maxbuf = (LONG_MAX / 3) / BKVASIZE; 933 if (nbuf > maxbuf) { 934 if (!tuned_nbuf) 935 printf("Warning: nbufs lowered from %d to %ld\n", nbuf, 936 maxbuf); 937 nbuf = maxbuf; 938 } 939 940 /* 941 * Ideal allocation size for the transient bio submap is 10% 942 * of the maximal space buffer map. This roughly corresponds 943 * to the amount of the buffer mapped for typical UFS load. 944 * 945 * Clip the buffer map to reserve space for the transient 946 * BIOs, if its extent is bigger than 90% (80% on i386) of the 947 * maximum buffer map extent on the platform. 948 * 949 * The fall-back to the maxbuf in case of maxbcache unset, 950 * allows to not trim the buffer KVA for the architectures 951 * with ample KVA space. 952 */ 953 if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) { 954 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE; 955 buf_sz = (long)nbuf * BKVASIZE; 956 if (buf_sz < maxbuf_sz / TRANSIENT_DENOM * 957 (TRANSIENT_DENOM - 1)) { 958 /* 959 * There is more KVA than memory. Do not 960 * adjust buffer map size, and assign the rest 961 * of maxbuf to transient map. 962 */ 963 biotmap_sz = maxbuf_sz - buf_sz; 964 } else { 965 /* 966 * Buffer map spans all KVA we could afford on 967 * this platform. Give 10% (20% on i386) of 968 * the buffer map to the transient bio map. 969 */ 970 biotmap_sz = buf_sz / TRANSIENT_DENOM; 971 buf_sz -= biotmap_sz; 972 } 973 if (biotmap_sz / INT_MAX > MAXPHYS) 974 bio_transient_maxcnt = INT_MAX; 975 else 976 bio_transient_maxcnt = biotmap_sz / MAXPHYS; 977 /* 978 * Artifically limit to 1024 simultaneous in-flight I/Os 979 * using the transient mapping. 980 */ 981 if (bio_transient_maxcnt > 1024) 982 bio_transient_maxcnt = 1024; 983 if (tuned_nbuf) 984 nbuf = buf_sz / BKVASIZE; 985 } 986 987 /* 988 * swbufs are used as temporary holders for I/O, such as paging I/O. 989 * We have no less then 16 and no more then 256. 990 */ 991 nswbuf = min(nbuf / 4, 256); 992 TUNABLE_INT_FETCH("kern.nswbuf", &nswbuf); 993 if (nswbuf < NSWBUF_MIN) 994 nswbuf = NSWBUF_MIN; 995 996 /* 997 * Reserve space for the buffer cache buffers 998 */ 999 swbuf = (void *)v; 1000 v = (caddr_t)(swbuf + nswbuf); 1001 buf = (void *)v; 1002 v = (caddr_t)(buf + nbuf); 1003 1004 return(v); 1005 } 1006 1007 /* Initialize the buffer subsystem. Called before use of any buffers. */ 1008 void 1009 bufinit(void) 1010 { 1011 struct buf *bp; 1012 int i; 1013 1014 CTASSERT(MAXBCACHEBUF >= MAXBSIZE); 1015 mtx_init(&bqlocks[QUEUE_DIRTY], "bufq dirty lock", NULL, MTX_DEF); 1016 mtx_init(&bqlocks[QUEUE_EMPTY], "bufq empty lock", NULL, MTX_DEF); 1017 for (i = QUEUE_CLEAN; i < QUEUE_CLEAN + CLEAN_QUEUES; i++) 1018 mtx_init(&bqlocks[i], "bufq clean lock", NULL, MTX_DEF); 1019 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 1020 rw_init(&nblock, "needsbuffer lock"); 1021 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 1022 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF); 1023 1024 /* next, make a null set of free lists */ 1025 for (i = 0; i < BUFFER_QUEUES; i++) 1026 TAILQ_INIT(&bufqueues[i]); 1027 1028 unmapped_buf = (caddr_t)kva_alloc(MAXPHYS); 1029 1030 /* finally, initialize each buffer header and stick on empty q */ 1031 for (i = 0; i < nbuf; i++) { 1032 bp = &buf[i]; 1033 bzero(bp, sizeof *bp); 1034 bp->b_flags = B_INVAL; 1035 bp->b_rcred = NOCRED; 1036 bp->b_wcred = NOCRED; 1037 bp->b_qindex = QUEUE_EMPTY; 1038 bp->b_xflags = 0; 1039 bp->b_data = bp->b_kvabase = unmapped_buf; 1040 LIST_INIT(&bp->b_dep); 1041 BUF_LOCKINIT(bp); 1042 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 1043 #ifdef INVARIANTS 1044 bq_len[QUEUE_EMPTY]++; 1045 #endif 1046 } 1047 1048 /* 1049 * maxbufspace is the absolute maximum amount of buffer space we are 1050 * allowed to reserve in KVM and in real terms. The absolute maximum 1051 * is nominally used by metadata. hibufspace is the nominal maximum 1052 * used by most other requests. The differential is required to 1053 * ensure that metadata deadlocks don't occur. 1054 * 1055 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 1056 * this may result in KVM fragmentation which is not handled optimally 1057 * by the system. XXX This is less true with vmem. We could use 1058 * PAGE_SIZE. 1059 */ 1060 maxbufspace = (long)nbuf * BKVASIZE; 1061 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - MAXBCACHEBUF * 10); 1062 lobufspace = (hibufspace / 20) * 19; /* 95% */ 1063 bufspacethresh = lobufspace + (hibufspace - lobufspace) / 2; 1064 1065 /* 1066 * Note: The 16 MiB upper limit for hirunningspace was chosen 1067 * arbitrarily and may need further tuning. It corresponds to 1068 * 128 outstanding write IO requests (if IO size is 128 KiB), 1069 * which fits with many RAID controllers' tagged queuing limits. 1070 * The lower 1 MiB limit is the historical upper limit for 1071 * hirunningspace. 1072 */ 1073 hirunningspace = lmax(lmin(roundup(hibufspace / 64, MAXBCACHEBUF), 1074 16 * 1024 * 1024), 1024 * 1024); 1075 lorunningspace = roundup((hirunningspace * 2) / 3, MAXBCACHEBUF); 1076 1077 /* 1078 * Limit the amount of malloc memory since it is wired permanently into 1079 * the kernel space. Even though this is accounted for in the buffer 1080 * allocation, we don't want the malloced region to grow uncontrolled. 1081 * The malloc scheme improves memory utilization significantly on 1082 * average (small) directories. 1083 */ 1084 maxbufmallocspace = hibufspace / 20; 1085 1086 /* 1087 * Reduce the chance of a deadlock occuring by limiting the number 1088 * of delayed-write dirty buffers we allow to stack up. 1089 */ 1090 hidirtybuffers = nbuf / 4 + 20; 1091 dirtybufthresh = hidirtybuffers * 9 / 10; 1092 numdirtybuffers = 0; 1093 /* 1094 * To support extreme low-memory systems, make sure hidirtybuffers 1095 * cannot eat up all available buffer space. This occurs when our 1096 * minimum cannot be met. We try to size hidirtybuffers to 3/4 our 1097 * buffer space assuming BKVASIZE'd buffers. 1098 */ 1099 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 1100 hidirtybuffers >>= 1; 1101 } 1102 lodirtybuffers = hidirtybuffers / 2; 1103 1104 /* 1105 * lofreebuffers should be sufficient to avoid stalling waiting on 1106 * buf headers under heavy utilization. The bufs in per-cpu caches 1107 * are counted as free but will be unavailable to threads executing 1108 * on other cpus. 1109 * 1110 * hifreebuffers is the free target for the bufspace daemon. This 1111 * should be set appropriately to limit work per-iteration. 1112 */ 1113 lofreebuffers = MIN((nbuf / 25) + (20 * mp_ncpus), 128 * mp_ncpus); 1114 hifreebuffers = (3 * lofreebuffers) / 2; 1115 numfreebuffers = nbuf; 1116 1117 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ | 1118 VM_ALLOC_NORMAL | VM_ALLOC_WIRED); 1119 1120 /* Setup the kva and free list allocators. */ 1121 vmem_set_reclaim(buffer_arena, bufkva_reclaim); 1122 buf_zone = uma_zcache_create("buf free cache", sizeof(struct buf), 1123 NULL, NULL, NULL, NULL, buf_import, buf_release, NULL, 0); 1124 1125 /* 1126 * Size the clean queue according to the amount of buffer space. 1127 * One queue per-256mb up to the max. More queues gives better 1128 * concurrency but less accurate LRU. 1129 */ 1130 clean_queues = MIN(howmany(maxbufspace, 256*1024*1024), CLEAN_QUEUES); 1131 1132 } 1133 1134 #ifdef INVARIANTS 1135 static inline void 1136 vfs_buf_check_mapped(struct buf *bp) 1137 { 1138 1139 KASSERT(bp->b_kvabase != unmapped_buf, 1140 ("mapped buf: b_kvabase was not updated %p", bp)); 1141 KASSERT(bp->b_data != unmapped_buf, 1142 ("mapped buf: b_data was not updated %p", bp)); 1143 KASSERT(bp->b_data < unmapped_buf || bp->b_data >= unmapped_buf + 1144 MAXPHYS, ("b_data + b_offset unmapped %p", bp)); 1145 } 1146 1147 static inline void 1148 vfs_buf_check_unmapped(struct buf *bp) 1149 { 1150 1151 KASSERT(bp->b_data == unmapped_buf, 1152 ("unmapped buf: corrupted b_data %p", bp)); 1153 } 1154 1155 #define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp) 1156 #define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp) 1157 #else 1158 #define BUF_CHECK_MAPPED(bp) do {} while (0) 1159 #define BUF_CHECK_UNMAPPED(bp) do {} while (0) 1160 #endif 1161 1162 static int 1163 isbufbusy(struct buf *bp) 1164 { 1165 if (((bp->b_flags & (B_INVAL | B_PERSISTENT)) == 0 && 1166 BUF_ISLOCKED(bp)) || 1167 ((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI)) 1168 return (1); 1169 return (0); 1170 } 1171 1172 /* 1173 * Shutdown the system cleanly to prepare for reboot, halt, or power off. 1174 */ 1175 void 1176 bufshutdown(int show_busybufs) 1177 { 1178 static int first_buf_printf = 1; 1179 struct buf *bp; 1180 int iter, nbusy, pbusy; 1181 #ifndef PREEMPTION 1182 int subiter; 1183 #endif 1184 1185 /* 1186 * Sync filesystems for shutdown 1187 */ 1188 wdog_kern_pat(WD_LASTVAL); 1189 sys_sync(curthread, NULL); 1190 1191 /* 1192 * With soft updates, some buffers that are 1193 * written will be remarked as dirty until other 1194 * buffers are written. 1195 */ 1196 for (iter = pbusy = 0; iter < 20; iter++) { 1197 nbusy = 0; 1198 for (bp = &buf[nbuf]; --bp >= buf; ) 1199 if (isbufbusy(bp)) 1200 nbusy++; 1201 if (nbusy == 0) { 1202 if (first_buf_printf) 1203 printf("All buffers synced."); 1204 break; 1205 } 1206 if (first_buf_printf) { 1207 printf("Syncing disks, buffers remaining... "); 1208 first_buf_printf = 0; 1209 } 1210 printf("%d ", nbusy); 1211 if (nbusy < pbusy) 1212 iter = 0; 1213 pbusy = nbusy; 1214 1215 wdog_kern_pat(WD_LASTVAL); 1216 sys_sync(curthread, NULL); 1217 1218 #ifdef PREEMPTION 1219 /* 1220 * Drop Giant and spin for a while to allow 1221 * interrupt threads to run. 1222 */ 1223 DROP_GIANT(); 1224 DELAY(50000 * iter); 1225 PICKUP_GIANT(); 1226 #else 1227 /* 1228 * Drop Giant and context switch several times to 1229 * allow interrupt threads to run. 1230 */ 1231 DROP_GIANT(); 1232 for (subiter = 0; subiter < 50 * iter; subiter++) { 1233 thread_lock(curthread); 1234 mi_switch(SW_VOL, NULL); 1235 thread_unlock(curthread); 1236 DELAY(1000); 1237 } 1238 PICKUP_GIANT(); 1239 #endif 1240 } 1241 printf("\n"); 1242 /* 1243 * Count only busy local buffers to prevent forcing 1244 * a fsck if we're just a client of a wedged NFS server 1245 */ 1246 nbusy = 0; 1247 for (bp = &buf[nbuf]; --bp >= buf; ) { 1248 if (isbufbusy(bp)) { 1249 #if 0 1250 /* XXX: This is bogus. We should probably have a BO_REMOTE flag instead */ 1251 if (bp->b_dev == NULL) { 1252 TAILQ_REMOVE(&mountlist, 1253 bp->b_vp->v_mount, mnt_list); 1254 continue; 1255 } 1256 #endif 1257 nbusy++; 1258 if (show_busybufs > 0) { 1259 printf( 1260 "%d: buf:%p, vnode:%p, flags:%0x, blkno:%jd, lblkno:%jd, buflock:", 1261 nbusy, bp, bp->b_vp, bp->b_flags, 1262 (intmax_t)bp->b_blkno, 1263 (intmax_t)bp->b_lblkno); 1264 BUF_LOCKPRINTINFO(bp); 1265 if (show_busybufs > 1) 1266 vn_printf(bp->b_vp, 1267 "vnode content: "); 1268 } 1269 } 1270 } 1271 if (nbusy) { 1272 /* 1273 * Failed to sync all blocks. Indicate this and don't 1274 * unmount filesystems (thus forcing an fsck on reboot). 1275 */ 1276 printf("Giving up on %d buffers\n", nbusy); 1277 DELAY(5000000); /* 5 seconds */ 1278 } else { 1279 if (!first_buf_printf) 1280 printf("Final sync complete\n"); 1281 /* 1282 * Unmount filesystems 1283 */ 1284 if (panicstr == NULL) 1285 vfs_unmountall(); 1286 } 1287 swapoff_all(); 1288 DELAY(100000); /* wait for console output to finish */ 1289 } 1290 1291 static void 1292 bpmap_qenter(struct buf *bp) 1293 { 1294 1295 BUF_CHECK_MAPPED(bp); 1296 1297 /* 1298 * bp->b_data is relative to bp->b_offset, but 1299 * bp->b_offset may be offset into the first page. 1300 */ 1301 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data); 1302 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages); 1303 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 1304 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 1305 } 1306 1307 /* 1308 * binsfree: 1309 * 1310 * Insert the buffer into the appropriate free list. 1311 */ 1312 static void 1313 binsfree(struct buf *bp, int qindex) 1314 { 1315 struct mtx *olock, *nlock; 1316 1317 if (qindex != QUEUE_EMPTY) { 1318 BUF_ASSERT_XLOCKED(bp); 1319 } 1320 1321 /* 1322 * Stick to the same clean queue for the lifetime of the buf to 1323 * limit locking below. Otherwise pick ont sequentially. 1324 */ 1325 if (qindex == QUEUE_CLEAN) { 1326 if (bqisclean(bp->b_qindex)) 1327 qindex = bp->b_qindex; 1328 else 1329 qindex = bqcleanq(); 1330 } 1331 1332 /* 1333 * Handle delayed bremfree() processing. 1334 */ 1335 nlock = bqlock(qindex); 1336 if (bp->b_flags & B_REMFREE) { 1337 olock = bqlock(bp->b_qindex); 1338 mtx_lock(olock); 1339 bremfreel(bp); 1340 if (olock != nlock) { 1341 mtx_unlock(olock); 1342 mtx_lock(nlock); 1343 } 1344 } else 1345 mtx_lock(nlock); 1346 1347 if (bp->b_qindex != QUEUE_NONE) 1348 panic("binsfree: free buffer onto another queue???"); 1349 1350 bp->b_qindex = qindex; 1351 if (bp->b_flags & B_AGE) 1352 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1353 else 1354 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1355 #ifdef INVARIANTS 1356 bq_len[bp->b_qindex]++; 1357 #endif 1358 mtx_unlock(nlock); 1359 } 1360 1361 /* 1362 * buf_free: 1363 * 1364 * Free a buffer to the buf zone once it no longer has valid contents. 1365 */ 1366 static void 1367 buf_free(struct buf *bp) 1368 { 1369 1370 if (bp->b_flags & B_REMFREE) 1371 bremfreef(bp); 1372 if (bp->b_vflags & BV_BKGRDINPROG) 1373 panic("losing buffer 1"); 1374 if (bp->b_rcred != NOCRED) { 1375 crfree(bp->b_rcred); 1376 bp->b_rcred = NOCRED; 1377 } 1378 if (bp->b_wcred != NOCRED) { 1379 crfree(bp->b_wcred); 1380 bp->b_wcred = NOCRED; 1381 } 1382 if (!LIST_EMPTY(&bp->b_dep)) 1383 buf_deallocate(bp); 1384 bufkva_free(bp); 1385 BUF_UNLOCK(bp); 1386 uma_zfree(buf_zone, bp); 1387 atomic_add_int(&numfreebuffers, 1); 1388 bufspace_wakeup(); 1389 } 1390 1391 /* 1392 * buf_import: 1393 * 1394 * Import bufs into the uma cache from the buf list. The system still 1395 * expects a static array of bufs and much of the synchronization 1396 * around bufs assumes type stable storage. As a result, UMA is used 1397 * only as a per-cpu cache of bufs still maintained on a global list. 1398 */ 1399 static int 1400 buf_import(void *arg, void **store, int cnt, int flags) 1401 { 1402 struct buf *bp; 1403 int i; 1404 1405 mtx_lock(&bqlocks[QUEUE_EMPTY]); 1406 for (i = 0; i < cnt; i++) { 1407 bp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1408 if (bp == NULL) 1409 break; 1410 bremfreel(bp); 1411 store[i] = bp; 1412 } 1413 mtx_unlock(&bqlocks[QUEUE_EMPTY]); 1414 1415 return (i); 1416 } 1417 1418 /* 1419 * buf_release: 1420 * 1421 * Release bufs from the uma cache back to the buffer queues. 1422 */ 1423 static void 1424 buf_release(void *arg, void **store, int cnt) 1425 { 1426 int i; 1427 1428 for (i = 0; i < cnt; i++) 1429 binsfree(store[i], QUEUE_EMPTY); 1430 } 1431 1432 /* 1433 * buf_alloc: 1434 * 1435 * Allocate an empty buffer header. 1436 */ 1437 static struct buf * 1438 buf_alloc(void) 1439 { 1440 struct buf *bp; 1441 1442 bp = uma_zalloc(buf_zone, M_NOWAIT); 1443 if (bp == NULL) { 1444 bufspace_daemonwakeup(); 1445 atomic_add_int(&numbufallocfails, 1); 1446 return (NULL); 1447 } 1448 1449 /* 1450 * Wake-up the bufspace daemon on transition. 1451 */ 1452 if (atomic_fetchadd_int(&numfreebuffers, -1) == lofreebuffers) 1453 bufspace_daemonwakeup(); 1454 1455 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1456 panic("getnewbuf_empty: Locked buf %p on free queue.", bp); 1457 1458 KASSERT(bp->b_vp == NULL, 1459 ("bp: %p still has vnode %p.", bp, bp->b_vp)); 1460 KASSERT((bp->b_flags & (B_DELWRI | B_NOREUSE)) == 0, 1461 ("invalid buffer %p flags %#x", bp, bp->b_flags)); 1462 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 1463 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags)); 1464 KASSERT(bp->b_npages == 0, 1465 ("bp: %p still has %d vm pages\n", bp, bp->b_npages)); 1466 KASSERT(bp->b_kvasize == 0, ("bp: %p still has kva\n", bp)); 1467 KASSERT(bp->b_bufsize == 0, ("bp: %p still has bufspace\n", bp)); 1468 1469 bp->b_flags = 0; 1470 bp->b_ioflags = 0; 1471 bp->b_xflags = 0; 1472 bp->b_vflags = 0; 1473 bp->b_vp = NULL; 1474 bp->b_blkno = bp->b_lblkno = 0; 1475 bp->b_offset = NOOFFSET; 1476 bp->b_iodone = 0; 1477 bp->b_error = 0; 1478 bp->b_resid = 0; 1479 bp->b_bcount = 0; 1480 bp->b_npages = 0; 1481 bp->b_dirtyoff = bp->b_dirtyend = 0; 1482 bp->b_bufobj = NULL; 1483 bp->b_pin_count = 0; 1484 bp->b_data = bp->b_kvabase = unmapped_buf; 1485 bp->b_fsprivate1 = NULL; 1486 bp->b_fsprivate2 = NULL; 1487 bp->b_fsprivate3 = NULL; 1488 LIST_INIT(&bp->b_dep); 1489 1490 return (bp); 1491 } 1492 1493 /* 1494 * buf_qrecycle: 1495 * 1496 * Free a buffer from the given bufqueue. kva controls whether the 1497 * freed buf must own some kva resources. This is used for 1498 * defragmenting. 1499 */ 1500 static int 1501 buf_qrecycle(int qindex, bool kva) 1502 { 1503 struct buf *bp, *nbp; 1504 1505 if (kva) 1506 atomic_add_int(&bufdefragcnt, 1); 1507 nbp = NULL; 1508 mtx_lock(&bqlocks[qindex]); 1509 nbp = TAILQ_FIRST(&bufqueues[qindex]); 1510 1511 /* 1512 * Run scan, possibly freeing data and/or kva mappings on the fly 1513 * depending. 1514 */ 1515 while ((bp = nbp) != NULL) { 1516 /* 1517 * Calculate next bp (we can only use it if we do not 1518 * release the bqlock). 1519 */ 1520 nbp = TAILQ_NEXT(bp, b_freelist); 1521 1522 /* 1523 * If we are defragging then we need a buffer with 1524 * some kva to reclaim. 1525 */ 1526 if (kva && bp->b_kvasize == 0) 1527 continue; 1528 1529 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1530 continue; 1531 1532 /* 1533 * Skip buffers with background writes in progress. 1534 */ 1535 if ((bp->b_vflags & BV_BKGRDINPROG) != 0) { 1536 BUF_UNLOCK(bp); 1537 continue; 1538 } 1539 1540 KASSERT(bp->b_qindex == qindex, 1541 ("getnewbuf: inconsistent queue %d bp %p", qindex, bp)); 1542 /* 1543 * NOTE: nbp is now entirely invalid. We can only restart 1544 * the scan from this point on. 1545 */ 1546 bremfreel(bp); 1547 mtx_unlock(&bqlocks[qindex]); 1548 1549 /* 1550 * Requeue the background write buffer with error and 1551 * restart the scan. 1552 */ 1553 if ((bp->b_vflags & BV_BKGRDERR) != 0) { 1554 bqrelse(bp); 1555 mtx_lock(&bqlocks[qindex]); 1556 nbp = TAILQ_FIRST(&bufqueues[qindex]); 1557 continue; 1558 } 1559 bp->b_flags |= B_INVAL; 1560 brelse(bp); 1561 return (0); 1562 } 1563 mtx_unlock(&bqlocks[qindex]); 1564 1565 return (ENOBUFS); 1566 } 1567 1568 /* 1569 * buf_recycle: 1570 * 1571 * Iterate through all clean queues until we find a buf to recycle or 1572 * exhaust the search. 1573 */ 1574 static int 1575 buf_recycle(bool kva) 1576 { 1577 int qindex, first_qindex; 1578 1579 qindex = first_qindex = bqcleanq(); 1580 do { 1581 if (buf_qrecycle(qindex, kva) == 0) 1582 return (0); 1583 if (++qindex == QUEUE_CLEAN + clean_queues) 1584 qindex = QUEUE_CLEAN; 1585 } while (qindex != first_qindex); 1586 1587 return (ENOBUFS); 1588 } 1589 1590 /* 1591 * buf_scan: 1592 * 1593 * Scan the clean queues looking for a buffer to recycle. needsbuffer 1594 * is set on failure so that the caller may optionally bufspace_wait() 1595 * in a race-free fashion. 1596 */ 1597 static int 1598 buf_scan(bool defrag) 1599 { 1600 int error; 1601 1602 /* 1603 * To avoid heavy synchronization and wakeup races we set 1604 * needsbuffer and re-poll before failing. This ensures that 1605 * no frees can be missed between an unsuccessful poll and 1606 * going to sleep in a synchronized fashion. 1607 */ 1608 if ((error = buf_recycle(defrag)) != 0) { 1609 atomic_set_int(&needsbuffer, 1); 1610 bufspace_daemonwakeup(); 1611 error = buf_recycle(defrag); 1612 } 1613 if (error == 0) 1614 atomic_add_int(&getnewbufrestarts, 1); 1615 return (error); 1616 } 1617 1618 /* 1619 * bremfree: 1620 * 1621 * Mark the buffer for removal from the appropriate free list. 1622 * 1623 */ 1624 void 1625 bremfree(struct buf *bp) 1626 { 1627 1628 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1629 KASSERT((bp->b_flags & B_REMFREE) == 0, 1630 ("bremfree: buffer %p already marked for delayed removal.", bp)); 1631 KASSERT(bp->b_qindex != QUEUE_NONE, 1632 ("bremfree: buffer %p not on a queue.", bp)); 1633 BUF_ASSERT_XLOCKED(bp); 1634 1635 bp->b_flags |= B_REMFREE; 1636 } 1637 1638 /* 1639 * bremfreef: 1640 * 1641 * Force an immediate removal from a free list. Used only in nfs when 1642 * it abuses the b_freelist pointer. 1643 */ 1644 void 1645 bremfreef(struct buf *bp) 1646 { 1647 struct mtx *qlock; 1648 1649 qlock = bqlock(bp->b_qindex); 1650 mtx_lock(qlock); 1651 bremfreel(bp); 1652 mtx_unlock(qlock); 1653 } 1654 1655 /* 1656 * bremfreel: 1657 * 1658 * Removes a buffer from the free list, must be called with the 1659 * correct qlock held. 1660 */ 1661 static void 1662 bremfreel(struct buf *bp) 1663 { 1664 1665 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X", 1666 bp, bp->b_vp, bp->b_flags); 1667 KASSERT(bp->b_qindex != QUEUE_NONE, 1668 ("bremfreel: buffer %p not on a queue.", bp)); 1669 if (bp->b_qindex != QUEUE_EMPTY) { 1670 BUF_ASSERT_XLOCKED(bp); 1671 } 1672 mtx_assert(bqlock(bp->b_qindex), MA_OWNED); 1673 1674 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 1675 #ifdef INVARIANTS 1676 KASSERT(bq_len[bp->b_qindex] >= 1, ("queue %d underflow", 1677 bp->b_qindex)); 1678 bq_len[bp->b_qindex]--; 1679 #endif 1680 bp->b_qindex = QUEUE_NONE; 1681 bp->b_flags &= ~B_REMFREE; 1682 } 1683 1684 /* 1685 * bufkva_free: 1686 * 1687 * Free the kva allocation for a buffer. 1688 * 1689 */ 1690 static void 1691 bufkva_free(struct buf *bp) 1692 { 1693 1694 #ifdef INVARIANTS 1695 if (bp->b_kvasize == 0) { 1696 KASSERT(bp->b_kvabase == unmapped_buf && 1697 bp->b_data == unmapped_buf, 1698 ("Leaked KVA space on %p", bp)); 1699 } else if (buf_mapped(bp)) 1700 BUF_CHECK_MAPPED(bp); 1701 else 1702 BUF_CHECK_UNMAPPED(bp); 1703 #endif 1704 if (bp->b_kvasize == 0) 1705 return; 1706 1707 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, bp->b_kvasize); 1708 atomic_subtract_long(&bufkvaspace, bp->b_kvasize); 1709 atomic_add_int(&buffreekvacnt, 1); 1710 bp->b_data = bp->b_kvabase = unmapped_buf; 1711 bp->b_kvasize = 0; 1712 } 1713 1714 /* 1715 * bufkva_alloc: 1716 * 1717 * Allocate the buffer KVA and set b_kvasize and b_kvabase. 1718 */ 1719 static int 1720 bufkva_alloc(struct buf *bp, int maxsize, int gbflags) 1721 { 1722 vm_offset_t addr; 1723 int error; 1724 1725 KASSERT((gbflags & GB_UNMAPPED) == 0 || (gbflags & GB_KVAALLOC) != 0, 1726 ("Invalid gbflags 0x%x in %s", gbflags, __func__)); 1727 1728 bufkva_free(bp); 1729 1730 addr = 0; 1731 error = vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr); 1732 if (error != 0) { 1733 /* 1734 * Buffer map is too fragmented. Request the caller 1735 * to defragment the map. 1736 */ 1737 return (error); 1738 } 1739 bp->b_kvabase = (caddr_t)addr; 1740 bp->b_kvasize = maxsize; 1741 atomic_add_long(&bufkvaspace, bp->b_kvasize); 1742 if ((gbflags & GB_UNMAPPED) != 0) { 1743 bp->b_data = unmapped_buf; 1744 BUF_CHECK_UNMAPPED(bp); 1745 } else { 1746 bp->b_data = bp->b_kvabase; 1747 BUF_CHECK_MAPPED(bp); 1748 } 1749 return (0); 1750 } 1751 1752 /* 1753 * bufkva_reclaim: 1754 * 1755 * Reclaim buffer kva by freeing buffers holding kva. This is a vmem 1756 * callback that fires to avoid returning failure. 1757 */ 1758 static void 1759 bufkva_reclaim(vmem_t *vmem, int flags) 1760 { 1761 int i; 1762 1763 for (i = 0; i < 5; i++) 1764 if (buf_scan(true) != 0) 1765 break; 1766 return; 1767 } 1768 1769 1770 /* 1771 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 1772 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 1773 * the buffer is valid and we do not have to do anything. 1774 */ 1775 void 1776 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, 1777 int cnt, struct ucred * cred) 1778 { 1779 struct buf *rabp; 1780 int i; 1781 1782 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 1783 if (inmem(vp, *rablkno)) 1784 continue; 1785 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 1786 1787 if ((rabp->b_flags & B_CACHE) == 0) { 1788 if (!TD_IS_IDLETHREAD(curthread)) { 1789 #ifdef RACCT 1790 if (racct_enable) { 1791 PROC_LOCK(curproc); 1792 racct_add_buf(curproc, rabp, 0); 1793 PROC_UNLOCK(curproc); 1794 } 1795 #endif /* RACCT */ 1796 curthread->td_ru.ru_inblock++; 1797 } 1798 rabp->b_flags |= B_ASYNC; 1799 rabp->b_flags &= ~B_INVAL; 1800 rabp->b_ioflags &= ~BIO_ERROR; 1801 rabp->b_iocmd = BIO_READ; 1802 if (rabp->b_rcred == NOCRED && cred != NOCRED) 1803 rabp->b_rcred = crhold(cred); 1804 vfs_busy_pages(rabp, 0); 1805 BUF_KERNPROC(rabp); 1806 rabp->b_iooffset = dbtob(rabp->b_blkno); 1807 bstrategy(rabp); 1808 } else { 1809 brelse(rabp); 1810 } 1811 } 1812 } 1813 1814 /* 1815 * Entry point for bread() and breadn() via #defines in sys/buf.h. 1816 * 1817 * Get a buffer with the specified data. Look in the cache first. We 1818 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 1819 * is set, the buffer is valid and we do not have to do anything, see 1820 * getblk(). Also starts asynchronous I/O on read-ahead blocks. 1821 * 1822 * Always return a NULL buffer pointer (in bpp) when returning an error. 1823 */ 1824 int 1825 breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno, 1826 int *rabsize, int cnt, struct ucred *cred, int flags, struct buf **bpp) 1827 { 1828 struct buf *bp; 1829 int rv = 0, readwait = 0; 1830 1831 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 1832 /* 1833 * Can only return NULL if GB_LOCK_NOWAIT flag is specified. 1834 */ 1835 *bpp = bp = getblk(vp, blkno, size, 0, 0, flags); 1836 if (bp == NULL) 1837 return (EBUSY); 1838 1839 /* if not found in cache, do some I/O */ 1840 if ((bp->b_flags & B_CACHE) == 0) { 1841 if (!TD_IS_IDLETHREAD(curthread)) { 1842 #ifdef RACCT 1843 if (racct_enable) { 1844 PROC_LOCK(curproc); 1845 racct_add_buf(curproc, bp, 0); 1846 PROC_UNLOCK(curproc); 1847 } 1848 #endif /* RACCT */ 1849 curthread->td_ru.ru_inblock++; 1850 } 1851 bp->b_iocmd = BIO_READ; 1852 bp->b_flags &= ~B_INVAL; 1853 bp->b_ioflags &= ~BIO_ERROR; 1854 if (bp->b_rcred == NOCRED && cred != NOCRED) 1855 bp->b_rcred = crhold(cred); 1856 vfs_busy_pages(bp, 0); 1857 bp->b_iooffset = dbtob(bp->b_blkno); 1858 bstrategy(bp); 1859 ++readwait; 1860 } 1861 1862 breada(vp, rablkno, rabsize, cnt, cred); 1863 1864 if (readwait) { 1865 rv = bufwait(bp); 1866 if (rv != 0) { 1867 brelse(bp); 1868 *bpp = NULL; 1869 } 1870 } 1871 return (rv); 1872 } 1873 1874 /* 1875 * Write, release buffer on completion. (Done by iodone 1876 * if async). Do not bother writing anything if the buffer 1877 * is invalid. 1878 * 1879 * Note that we set B_CACHE here, indicating that buffer is 1880 * fully valid and thus cacheable. This is true even of NFS 1881 * now so we set it generally. This could be set either here 1882 * or in biodone() since the I/O is synchronous. We put it 1883 * here. 1884 */ 1885 int 1886 bufwrite(struct buf *bp) 1887 { 1888 int oldflags; 1889 struct vnode *vp; 1890 long space; 1891 int vp_md; 1892 1893 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1894 if ((bp->b_bufobj->bo_flag & BO_DEAD) != 0) { 1895 bp->b_flags |= B_INVAL | B_RELBUF; 1896 bp->b_flags &= ~B_CACHE; 1897 brelse(bp); 1898 return (ENXIO); 1899 } 1900 if (bp->b_flags & B_INVAL) { 1901 brelse(bp); 1902 return (0); 1903 } 1904 1905 if (bp->b_flags & B_BARRIER) 1906 barrierwrites++; 1907 1908 oldflags = bp->b_flags; 1909 1910 BUF_ASSERT_HELD(bp); 1911 1912 if (bp->b_pin_count > 0) 1913 bunpin_wait(bp); 1914 1915 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 1916 ("FFS background buffer should not get here %p", bp)); 1917 1918 vp = bp->b_vp; 1919 if (vp) 1920 vp_md = vp->v_vflag & VV_MD; 1921 else 1922 vp_md = 0; 1923 1924 /* 1925 * Mark the buffer clean. Increment the bufobj write count 1926 * before bundirty() call, to prevent other thread from seeing 1927 * empty dirty list and zero counter for writes in progress, 1928 * falsely indicating that the bufobj is clean. 1929 */ 1930 bufobj_wref(bp->b_bufobj); 1931 bundirty(bp); 1932 1933 bp->b_flags &= ~B_DONE; 1934 bp->b_ioflags &= ~BIO_ERROR; 1935 bp->b_flags |= B_CACHE; 1936 bp->b_iocmd = BIO_WRITE; 1937 1938 vfs_busy_pages(bp, 1); 1939 1940 /* 1941 * Normal bwrites pipeline writes 1942 */ 1943 bp->b_runningbufspace = bp->b_bufsize; 1944 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace); 1945 1946 if (!TD_IS_IDLETHREAD(curthread)) { 1947 #ifdef RACCT 1948 if (racct_enable) { 1949 PROC_LOCK(curproc); 1950 racct_add_buf(curproc, bp, 1); 1951 PROC_UNLOCK(curproc); 1952 } 1953 #endif /* RACCT */ 1954 curthread->td_ru.ru_oublock++; 1955 } 1956 if (oldflags & B_ASYNC) 1957 BUF_KERNPROC(bp); 1958 bp->b_iooffset = dbtob(bp->b_blkno); 1959 bstrategy(bp); 1960 1961 if ((oldflags & B_ASYNC) == 0) { 1962 int rtval = bufwait(bp); 1963 brelse(bp); 1964 return (rtval); 1965 } else if (space > hirunningspace) { 1966 /* 1967 * don't allow the async write to saturate the I/O 1968 * system. We will not deadlock here because 1969 * we are blocking waiting for I/O that is already in-progress 1970 * to complete. We do not block here if it is the update 1971 * or syncer daemon trying to clean up as that can lead 1972 * to deadlock. 1973 */ 1974 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 1975 waitrunningbufspace(); 1976 } 1977 1978 return (0); 1979 } 1980 1981 void 1982 bufbdflush(struct bufobj *bo, struct buf *bp) 1983 { 1984 struct buf *nbp; 1985 1986 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 1987 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 1988 altbufferflushes++; 1989 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 1990 BO_LOCK(bo); 1991 /* 1992 * Try to find a buffer to flush. 1993 */ 1994 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 1995 if ((nbp->b_vflags & BV_BKGRDINPROG) || 1996 BUF_LOCK(nbp, 1997 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 1998 continue; 1999 if (bp == nbp) 2000 panic("bdwrite: found ourselves"); 2001 BO_UNLOCK(bo); 2002 /* Don't countdeps with the bo lock held. */ 2003 if (buf_countdeps(nbp, 0)) { 2004 BO_LOCK(bo); 2005 BUF_UNLOCK(nbp); 2006 continue; 2007 } 2008 if (nbp->b_flags & B_CLUSTEROK) { 2009 vfs_bio_awrite(nbp); 2010 } else { 2011 bremfree(nbp); 2012 bawrite(nbp); 2013 } 2014 dirtybufferflushes++; 2015 break; 2016 } 2017 if (nbp == NULL) 2018 BO_UNLOCK(bo); 2019 } 2020 } 2021 2022 /* 2023 * Delayed write. (Buffer is marked dirty). Do not bother writing 2024 * anything if the buffer is marked invalid. 2025 * 2026 * Note that since the buffer must be completely valid, we can safely 2027 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 2028 * biodone() in order to prevent getblk from writing the buffer 2029 * out synchronously. 2030 */ 2031 void 2032 bdwrite(struct buf *bp) 2033 { 2034 struct thread *td = curthread; 2035 struct vnode *vp; 2036 struct bufobj *bo; 2037 2038 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2039 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2040 KASSERT((bp->b_flags & B_BARRIER) == 0, 2041 ("Barrier request in delayed write %p", bp)); 2042 BUF_ASSERT_HELD(bp); 2043 2044 if (bp->b_flags & B_INVAL) { 2045 brelse(bp); 2046 return; 2047 } 2048 2049 /* 2050 * If we have too many dirty buffers, don't create any more. 2051 * If we are wildly over our limit, then force a complete 2052 * cleanup. Otherwise, just keep the situation from getting 2053 * out of control. Note that we have to avoid a recursive 2054 * disaster and not try to clean up after our own cleanup! 2055 */ 2056 vp = bp->b_vp; 2057 bo = bp->b_bufobj; 2058 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 2059 td->td_pflags |= TDP_INBDFLUSH; 2060 BO_BDFLUSH(bo, bp); 2061 td->td_pflags &= ~TDP_INBDFLUSH; 2062 } else 2063 recursiveflushes++; 2064 2065 bdirty(bp); 2066 /* 2067 * Set B_CACHE, indicating that the buffer is fully valid. This is 2068 * true even of NFS now. 2069 */ 2070 bp->b_flags |= B_CACHE; 2071 2072 /* 2073 * This bmap keeps the system from needing to do the bmap later, 2074 * perhaps when the system is attempting to do a sync. Since it 2075 * is likely that the indirect block -- or whatever other datastructure 2076 * that the filesystem needs is still in memory now, it is a good 2077 * thing to do this. Note also, that if the pageout daemon is 2078 * requesting a sync -- there might not be enough memory to do 2079 * the bmap then... So, this is important to do. 2080 */ 2081 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 2082 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 2083 } 2084 2085 /* 2086 * Set the *dirty* buffer range based upon the VM system dirty 2087 * pages. 2088 * 2089 * Mark the buffer pages as clean. We need to do this here to 2090 * satisfy the vnode_pager and the pageout daemon, so that it 2091 * thinks that the pages have been "cleaned". Note that since 2092 * the pages are in a delayed write buffer -- the VFS layer 2093 * "will" see that the pages get written out on the next sync, 2094 * or perhaps the cluster will be completed. 2095 */ 2096 vfs_clean_pages_dirty_buf(bp); 2097 bqrelse(bp); 2098 2099 /* 2100 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 2101 * due to the softdep code. 2102 */ 2103 } 2104 2105 /* 2106 * bdirty: 2107 * 2108 * Turn buffer into delayed write request. We must clear BIO_READ and 2109 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 2110 * itself to properly update it in the dirty/clean lists. We mark it 2111 * B_DONE to ensure that any asynchronization of the buffer properly 2112 * clears B_DONE ( else a panic will occur later ). 2113 * 2114 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 2115 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 2116 * should only be called if the buffer is known-good. 2117 * 2118 * Since the buffer is not on a queue, we do not update the numfreebuffers 2119 * count. 2120 * 2121 * The buffer must be on QUEUE_NONE. 2122 */ 2123 void 2124 bdirty(struct buf *bp) 2125 { 2126 2127 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 2128 bp, bp->b_vp, bp->b_flags); 2129 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2130 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 2131 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 2132 BUF_ASSERT_HELD(bp); 2133 bp->b_flags &= ~(B_RELBUF); 2134 bp->b_iocmd = BIO_WRITE; 2135 2136 if ((bp->b_flags & B_DELWRI) == 0) { 2137 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 2138 reassignbuf(bp); 2139 bdirtyadd(); 2140 } 2141 } 2142 2143 /* 2144 * bundirty: 2145 * 2146 * Clear B_DELWRI for buffer. 2147 * 2148 * Since the buffer is not on a queue, we do not update the numfreebuffers 2149 * count. 2150 * 2151 * The buffer must be on QUEUE_NONE. 2152 */ 2153 2154 void 2155 bundirty(struct buf *bp) 2156 { 2157 2158 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2159 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2160 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 2161 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 2162 BUF_ASSERT_HELD(bp); 2163 2164 if (bp->b_flags & B_DELWRI) { 2165 bp->b_flags &= ~B_DELWRI; 2166 reassignbuf(bp); 2167 bdirtysub(); 2168 } 2169 /* 2170 * Since it is now being written, we can clear its deferred write flag. 2171 */ 2172 bp->b_flags &= ~B_DEFERRED; 2173 } 2174 2175 /* 2176 * bawrite: 2177 * 2178 * Asynchronous write. Start output on a buffer, but do not wait for 2179 * it to complete. The buffer is released when the output completes. 2180 * 2181 * bwrite() ( or the VOP routine anyway ) is responsible for handling 2182 * B_INVAL buffers. Not us. 2183 */ 2184 void 2185 bawrite(struct buf *bp) 2186 { 2187 2188 bp->b_flags |= B_ASYNC; 2189 (void) bwrite(bp); 2190 } 2191 2192 /* 2193 * babarrierwrite: 2194 * 2195 * Asynchronous barrier write. Start output on a buffer, but do not 2196 * wait for it to complete. Place a write barrier after this write so 2197 * that this buffer and all buffers written before it are committed to 2198 * the disk before any buffers written after this write are committed 2199 * to the disk. The buffer is released when the output completes. 2200 */ 2201 void 2202 babarrierwrite(struct buf *bp) 2203 { 2204 2205 bp->b_flags |= B_ASYNC | B_BARRIER; 2206 (void) bwrite(bp); 2207 } 2208 2209 /* 2210 * bbarrierwrite: 2211 * 2212 * Synchronous barrier write. Start output on a buffer and wait for 2213 * it to complete. Place a write barrier after this write so that 2214 * this buffer and all buffers written before it are committed to 2215 * the disk before any buffers written after this write are committed 2216 * to the disk. The buffer is released when the output completes. 2217 */ 2218 int 2219 bbarrierwrite(struct buf *bp) 2220 { 2221 2222 bp->b_flags |= B_BARRIER; 2223 return (bwrite(bp)); 2224 } 2225 2226 /* 2227 * bwillwrite: 2228 * 2229 * Called prior to the locking of any vnodes when we are expecting to 2230 * write. We do not want to starve the buffer cache with too many 2231 * dirty buffers so we block here. By blocking prior to the locking 2232 * of any vnodes we attempt to avoid the situation where a locked vnode 2233 * prevents the various system daemons from flushing related buffers. 2234 */ 2235 void 2236 bwillwrite(void) 2237 { 2238 2239 if (numdirtybuffers >= hidirtybuffers) { 2240 mtx_lock(&bdirtylock); 2241 while (numdirtybuffers >= hidirtybuffers) { 2242 bdirtywait = 1; 2243 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4), 2244 "flswai", 0); 2245 } 2246 mtx_unlock(&bdirtylock); 2247 } 2248 } 2249 2250 /* 2251 * Return true if we have too many dirty buffers. 2252 */ 2253 int 2254 buf_dirty_count_severe(void) 2255 { 2256 2257 return(numdirtybuffers >= hidirtybuffers); 2258 } 2259 2260 /* 2261 * brelse: 2262 * 2263 * Release a busy buffer and, if requested, free its resources. The 2264 * buffer will be stashed in the appropriate bufqueue[] allowing it 2265 * to be accessed later as a cache entity or reused for other purposes. 2266 */ 2267 void 2268 brelse(struct buf *bp) 2269 { 2270 int qindex; 2271 2272 /* 2273 * Many functions erroneously call brelse with a NULL bp under rare 2274 * error conditions. Simply return when called with a NULL bp. 2275 */ 2276 if (bp == NULL) 2277 return; 2278 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 2279 bp, bp->b_vp, bp->b_flags); 2280 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 2281 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 2282 KASSERT((bp->b_flags & B_VMIO) != 0 || (bp->b_flags & B_NOREUSE) == 0, 2283 ("brelse: non-VMIO buffer marked NOREUSE")); 2284 2285 if (BUF_LOCKRECURSED(bp)) { 2286 /* 2287 * Do not process, in particular, do not handle the 2288 * B_INVAL/B_RELBUF and do not release to free list. 2289 */ 2290 BUF_UNLOCK(bp); 2291 return; 2292 } 2293 2294 if (bp->b_flags & B_MANAGED) { 2295 bqrelse(bp); 2296 return; 2297 } 2298 2299 if ((bp->b_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) { 2300 BO_LOCK(bp->b_bufobj); 2301 bp->b_vflags &= ~BV_BKGRDERR; 2302 BO_UNLOCK(bp->b_bufobj); 2303 bdirty(bp); 2304 } 2305 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 2306 !(bp->b_flags & B_INVAL)) { 2307 /* 2308 * Failed write, redirty. Must clear BIO_ERROR to prevent 2309 * pages from being scrapped. 2310 */ 2311 bp->b_ioflags &= ~BIO_ERROR; 2312 bdirty(bp); 2313 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 2314 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 2315 /* 2316 * Either a failed read I/O or we were asked to free or not 2317 * cache the buffer. 2318 */ 2319 bp->b_flags |= B_INVAL; 2320 if (!LIST_EMPTY(&bp->b_dep)) 2321 buf_deallocate(bp); 2322 if (bp->b_flags & B_DELWRI) 2323 bdirtysub(); 2324 bp->b_flags &= ~(B_DELWRI | B_CACHE); 2325 if ((bp->b_flags & B_VMIO) == 0) { 2326 allocbuf(bp, 0); 2327 if (bp->b_vp) 2328 brelvp(bp); 2329 } 2330 } 2331 2332 /* 2333 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_truncate() 2334 * is called with B_DELWRI set, the underlying pages may wind up 2335 * getting freed causing a previous write (bdwrite()) to get 'lost' 2336 * because pages associated with a B_DELWRI bp are marked clean. 2337 * 2338 * We still allow the B_INVAL case to call vfs_vmio_truncate(), even 2339 * if B_DELWRI is set. 2340 */ 2341 if (bp->b_flags & B_DELWRI) 2342 bp->b_flags &= ~B_RELBUF; 2343 2344 /* 2345 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 2346 * constituted, not even NFS buffers now. Two flags effect this. If 2347 * B_INVAL, the struct buf is invalidated but the VM object is kept 2348 * around ( i.e. so it is trivial to reconstitute the buffer later ). 2349 * 2350 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 2351 * invalidated. BIO_ERROR cannot be set for a failed write unless the 2352 * buffer is also B_INVAL because it hits the re-dirtying code above. 2353 * 2354 * Normally we can do this whether a buffer is B_DELWRI or not. If 2355 * the buffer is an NFS buffer, it is tracking piecemeal writes or 2356 * the commit state and we cannot afford to lose the buffer. If the 2357 * buffer has a background write in progress, we need to keep it 2358 * around to prevent it from being reconstituted and starting a second 2359 * background write. 2360 */ 2361 if ((bp->b_flags & B_VMIO) && (bp->b_flags & B_NOCACHE || 2362 (bp->b_ioflags & BIO_ERROR && bp->b_iocmd == BIO_READ)) && 2363 !(bp->b_vp->v_mount != NULL && 2364 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 2365 !vn_isdisk(bp->b_vp, NULL) && (bp->b_flags & B_DELWRI))) { 2366 vfs_vmio_invalidate(bp); 2367 allocbuf(bp, 0); 2368 } 2369 2370 if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0 || 2371 (bp->b_flags & (B_DELWRI | B_NOREUSE)) == B_NOREUSE) { 2372 allocbuf(bp, 0); 2373 bp->b_flags &= ~B_NOREUSE; 2374 if (bp->b_vp != NULL) 2375 brelvp(bp); 2376 } 2377 2378 /* 2379 * If the buffer has junk contents signal it and eventually 2380 * clean up B_DELWRI and diassociate the vnode so that gbincore() 2381 * doesn't find it. 2382 */ 2383 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 2384 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 2385 bp->b_flags |= B_INVAL; 2386 if (bp->b_flags & B_INVAL) { 2387 if (bp->b_flags & B_DELWRI) 2388 bundirty(bp); 2389 if (bp->b_vp) 2390 brelvp(bp); 2391 } 2392 2393 /* buffers with no memory */ 2394 if (bp->b_bufsize == 0) { 2395 buf_free(bp); 2396 return; 2397 } 2398 /* buffers with junk contents */ 2399 if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 2400 (bp->b_ioflags & BIO_ERROR)) { 2401 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 2402 if (bp->b_vflags & BV_BKGRDINPROG) 2403 panic("losing buffer 2"); 2404 qindex = QUEUE_CLEAN; 2405 bp->b_flags |= B_AGE; 2406 /* remaining buffers */ 2407 } else if (bp->b_flags & B_DELWRI) 2408 qindex = QUEUE_DIRTY; 2409 else 2410 qindex = QUEUE_CLEAN; 2411 2412 binsfree(bp, qindex); 2413 2414 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 2415 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 2416 panic("brelse: not dirty"); 2417 /* unlock */ 2418 BUF_UNLOCK(bp); 2419 if (qindex == QUEUE_CLEAN) 2420 bufspace_wakeup(); 2421 } 2422 2423 /* 2424 * Release a buffer back to the appropriate queue but do not try to free 2425 * it. The buffer is expected to be used again soon. 2426 * 2427 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 2428 * biodone() to requeue an async I/O on completion. It is also used when 2429 * known good buffers need to be requeued but we think we may need the data 2430 * again soon. 2431 * 2432 * XXX we should be able to leave the B_RELBUF hint set on completion. 2433 */ 2434 void 2435 bqrelse(struct buf *bp) 2436 { 2437 int qindex; 2438 2439 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2440 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 2441 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 2442 2443 qindex = QUEUE_NONE; 2444 if (BUF_LOCKRECURSED(bp)) { 2445 /* do not release to free list */ 2446 BUF_UNLOCK(bp); 2447 return; 2448 } 2449 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 2450 2451 if (bp->b_flags & B_MANAGED) { 2452 if (bp->b_flags & B_REMFREE) 2453 bremfreef(bp); 2454 goto out; 2455 } 2456 2457 /* buffers with stale but valid contents */ 2458 if ((bp->b_flags & B_DELWRI) != 0 || (bp->b_vflags & (BV_BKGRDINPROG | 2459 BV_BKGRDERR)) == BV_BKGRDERR) { 2460 BO_LOCK(bp->b_bufobj); 2461 bp->b_vflags &= ~BV_BKGRDERR; 2462 BO_UNLOCK(bp->b_bufobj); 2463 qindex = QUEUE_DIRTY; 2464 } else { 2465 if ((bp->b_flags & B_DELWRI) == 0 && 2466 (bp->b_xflags & BX_VNDIRTY)) 2467 panic("bqrelse: not dirty"); 2468 if ((bp->b_flags & B_NOREUSE) != 0) { 2469 brelse(bp); 2470 return; 2471 } 2472 qindex = QUEUE_CLEAN; 2473 } 2474 binsfree(bp, qindex); 2475 2476 out: 2477 /* unlock */ 2478 BUF_UNLOCK(bp); 2479 if (qindex == QUEUE_CLEAN) 2480 bufspace_wakeup(); 2481 } 2482 2483 /* 2484 * Complete I/O to a VMIO backed page. Validate the pages as appropriate, 2485 * restore bogus pages. 2486 */ 2487 static void 2488 vfs_vmio_iodone(struct buf *bp) 2489 { 2490 vm_ooffset_t foff; 2491 vm_page_t m; 2492 vm_object_t obj; 2493 struct vnode *vp; 2494 int bogus, i, iosize; 2495 2496 obj = bp->b_bufobj->bo_object; 2497 KASSERT(obj->paging_in_progress >= bp->b_npages, 2498 ("vfs_vmio_iodone: paging in progress(%d) < b_npages(%d)", 2499 obj->paging_in_progress, bp->b_npages)); 2500 2501 vp = bp->b_vp; 2502 KASSERT(vp->v_holdcnt > 0, 2503 ("vfs_vmio_iodone: vnode %p has zero hold count", vp)); 2504 KASSERT(vp->v_object != NULL, 2505 ("vfs_vmio_iodone: vnode %p has no vm_object", vp)); 2506 2507 foff = bp->b_offset; 2508 KASSERT(bp->b_offset != NOOFFSET, 2509 ("vfs_vmio_iodone: bp %p has no buffer offset", bp)); 2510 2511 bogus = 0; 2512 iosize = bp->b_bcount - bp->b_resid; 2513 VM_OBJECT_WLOCK(obj); 2514 for (i = 0; i < bp->b_npages; i++) { 2515 int resid; 2516 2517 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 2518 if (resid > iosize) 2519 resid = iosize; 2520 2521 /* 2522 * cleanup bogus pages, restoring the originals 2523 */ 2524 m = bp->b_pages[i]; 2525 if (m == bogus_page) { 2526 bogus = 1; 2527 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 2528 if (m == NULL) 2529 panic("biodone: page disappeared!"); 2530 bp->b_pages[i] = m; 2531 } else if ((bp->b_iocmd == BIO_READ) && resid > 0) { 2532 /* 2533 * In the write case, the valid and clean bits are 2534 * already changed correctly ( see bdwrite() ), so we 2535 * only need to do this here in the read case. 2536 */ 2537 KASSERT((m->dirty & vm_page_bits(foff & PAGE_MASK, 2538 resid)) == 0, ("vfs_vmio_iodone: page %p " 2539 "has unexpected dirty bits", m)); 2540 vfs_page_set_valid(bp, foff, m); 2541 } 2542 KASSERT(OFF_TO_IDX(foff) == m->pindex, 2543 ("vfs_vmio_iodone: foff(%jd)/pindex(%ju) mismatch", 2544 (intmax_t)foff, (uintmax_t)m->pindex)); 2545 2546 vm_page_sunbusy(m); 2547 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2548 iosize -= resid; 2549 } 2550 vm_object_pip_wakeupn(obj, bp->b_npages); 2551 VM_OBJECT_WUNLOCK(obj); 2552 if (bogus && buf_mapped(bp)) { 2553 BUF_CHECK_MAPPED(bp); 2554 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 2555 bp->b_pages, bp->b_npages); 2556 } 2557 } 2558 2559 /* 2560 * Unwire a page held by a buf and place it on the appropriate vm queue. 2561 */ 2562 static void 2563 vfs_vmio_unwire(struct buf *bp, vm_page_t m) 2564 { 2565 bool freed; 2566 2567 vm_page_lock(m); 2568 if (vm_page_unwire(m, PQ_NONE)) { 2569 /* 2570 * Determine if the page should be freed before adding 2571 * it to the inactive queue. 2572 */ 2573 if (m->valid == 0) { 2574 freed = !vm_page_busied(m); 2575 if (freed) 2576 vm_page_free(m); 2577 } else if ((bp->b_flags & B_DIRECT) != 0) 2578 freed = vm_page_try_to_free(m); 2579 else 2580 freed = false; 2581 if (!freed) { 2582 /* 2583 * If the page is unlikely to be reused, let the 2584 * VM know. Otherwise, maintain LRU page 2585 * ordering and put the page at the tail of the 2586 * inactive queue. 2587 */ 2588 if ((bp->b_flags & B_NOREUSE) != 0) 2589 vm_page_deactivate_noreuse(m); 2590 else 2591 vm_page_deactivate(m); 2592 } 2593 } 2594 vm_page_unlock(m); 2595 } 2596 2597 /* 2598 * Perform page invalidation when a buffer is released. The fully invalid 2599 * pages will be reclaimed later in vfs_vmio_truncate(). 2600 */ 2601 static void 2602 vfs_vmio_invalidate(struct buf *bp) 2603 { 2604 vm_object_t obj; 2605 vm_page_t m; 2606 int i, resid, poffset, presid; 2607 2608 if (buf_mapped(bp)) { 2609 BUF_CHECK_MAPPED(bp); 2610 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages); 2611 } else 2612 BUF_CHECK_UNMAPPED(bp); 2613 /* 2614 * Get the base offset and length of the buffer. Note that 2615 * in the VMIO case if the buffer block size is not 2616 * page-aligned then b_data pointer may not be page-aligned. 2617 * But our b_pages[] array *IS* page aligned. 2618 * 2619 * block sizes less then DEV_BSIZE (usually 512) are not 2620 * supported due to the page granularity bits (m->valid, 2621 * m->dirty, etc...). 2622 * 2623 * See man buf(9) for more information 2624 */ 2625 obj = bp->b_bufobj->bo_object; 2626 resid = bp->b_bufsize; 2627 poffset = bp->b_offset & PAGE_MASK; 2628 VM_OBJECT_WLOCK(obj); 2629 for (i = 0; i < bp->b_npages; i++) { 2630 m = bp->b_pages[i]; 2631 if (m == bogus_page) 2632 panic("vfs_vmio_invalidate: Unexpected bogus page."); 2633 bp->b_pages[i] = NULL; 2634 2635 presid = resid > (PAGE_SIZE - poffset) ? 2636 (PAGE_SIZE - poffset) : resid; 2637 KASSERT(presid >= 0, ("brelse: extra page")); 2638 while (vm_page_xbusied(m)) { 2639 vm_page_lock(m); 2640 VM_OBJECT_WUNLOCK(obj); 2641 vm_page_busy_sleep(m, "mbncsh"); 2642 VM_OBJECT_WLOCK(obj); 2643 } 2644 if (pmap_page_wired_mappings(m) == 0) 2645 vm_page_set_invalid(m, poffset, presid); 2646 vfs_vmio_unwire(bp, m); 2647 resid -= presid; 2648 poffset = 0; 2649 } 2650 VM_OBJECT_WUNLOCK(obj); 2651 bp->b_npages = 0; 2652 } 2653 2654 /* 2655 * Page-granular truncation of an existing VMIO buffer. 2656 */ 2657 static void 2658 vfs_vmio_truncate(struct buf *bp, int desiredpages) 2659 { 2660 vm_object_t obj; 2661 vm_page_t m; 2662 int i; 2663 2664 if (bp->b_npages == desiredpages) 2665 return; 2666 2667 if (buf_mapped(bp)) { 2668 BUF_CHECK_MAPPED(bp); 2669 pmap_qremove((vm_offset_t)trunc_page((vm_offset_t)bp->b_data) + 2670 (desiredpages << PAGE_SHIFT), bp->b_npages - desiredpages); 2671 } else 2672 BUF_CHECK_UNMAPPED(bp); 2673 obj = bp->b_bufobj->bo_object; 2674 if (obj != NULL) 2675 VM_OBJECT_WLOCK(obj); 2676 for (i = desiredpages; i < bp->b_npages; i++) { 2677 m = bp->b_pages[i]; 2678 KASSERT(m != bogus_page, ("allocbuf: bogus page found")); 2679 bp->b_pages[i] = NULL; 2680 vfs_vmio_unwire(bp, m); 2681 } 2682 if (obj != NULL) 2683 VM_OBJECT_WUNLOCK(obj); 2684 bp->b_npages = desiredpages; 2685 } 2686 2687 /* 2688 * Byte granular extension of VMIO buffers. 2689 */ 2690 static void 2691 vfs_vmio_extend(struct buf *bp, int desiredpages, int size) 2692 { 2693 /* 2694 * We are growing the buffer, possibly in a 2695 * byte-granular fashion. 2696 */ 2697 vm_object_t obj; 2698 vm_offset_t toff; 2699 vm_offset_t tinc; 2700 vm_page_t m; 2701 2702 /* 2703 * Step 1, bring in the VM pages from the object, allocating 2704 * them if necessary. We must clear B_CACHE if these pages 2705 * are not valid for the range covered by the buffer. 2706 */ 2707 obj = bp->b_bufobj->bo_object; 2708 VM_OBJECT_WLOCK(obj); 2709 while (bp->b_npages < desiredpages) { 2710 /* 2711 * We must allocate system pages since blocking 2712 * here could interfere with paging I/O, no 2713 * matter which process we are. 2714 * 2715 * Only exclusive busy can be tested here. 2716 * Blocking on shared busy might lead to 2717 * deadlocks once allocbuf() is called after 2718 * pages are vfs_busy_pages(). 2719 */ 2720 m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) + bp->b_npages, 2721 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM | 2722 VM_ALLOC_WIRED | VM_ALLOC_IGN_SBUSY | 2723 VM_ALLOC_COUNT(desiredpages - bp->b_npages)); 2724 if (m->valid == 0) 2725 bp->b_flags &= ~B_CACHE; 2726 bp->b_pages[bp->b_npages] = m; 2727 ++bp->b_npages; 2728 } 2729 2730 /* 2731 * Step 2. We've loaded the pages into the buffer, 2732 * we have to figure out if we can still have B_CACHE 2733 * set. Note that B_CACHE is set according to the 2734 * byte-granular range ( bcount and size ), not the 2735 * aligned range ( newbsize ). 2736 * 2737 * The VM test is against m->valid, which is DEV_BSIZE 2738 * aligned. Needless to say, the validity of the data 2739 * needs to also be DEV_BSIZE aligned. Note that this 2740 * fails with NFS if the server or some other client 2741 * extends the file's EOF. If our buffer is resized, 2742 * B_CACHE may remain set! XXX 2743 */ 2744 toff = bp->b_bcount; 2745 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 2746 while ((bp->b_flags & B_CACHE) && toff < size) { 2747 vm_pindex_t pi; 2748 2749 if (tinc > (size - toff)) 2750 tinc = size - toff; 2751 pi = ((bp->b_offset & PAGE_MASK) + toff) >> PAGE_SHIFT; 2752 m = bp->b_pages[pi]; 2753 vfs_buf_test_cache(bp, bp->b_offset, toff, tinc, m); 2754 toff += tinc; 2755 tinc = PAGE_SIZE; 2756 } 2757 VM_OBJECT_WUNLOCK(obj); 2758 2759 /* 2760 * Step 3, fixup the KVA pmap. 2761 */ 2762 if (buf_mapped(bp)) 2763 bpmap_qenter(bp); 2764 else 2765 BUF_CHECK_UNMAPPED(bp); 2766 } 2767 2768 /* 2769 * Check to see if a block at a particular lbn is available for a clustered 2770 * write. 2771 */ 2772 static int 2773 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 2774 { 2775 struct buf *bpa; 2776 int match; 2777 2778 match = 0; 2779 2780 /* If the buf isn't in core skip it */ 2781 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 2782 return (0); 2783 2784 /* If the buf is busy we don't want to wait for it */ 2785 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2786 return (0); 2787 2788 /* Only cluster with valid clusterable delayed write buffers */ 2789 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 2790 (B_DELWRI | B_CLUSTEROK)) 2791 goto done; 2792 2793 if (bpa->b_bufsize != size) 2794 goto done; 2795 2796 /* 2797 * Check to see if it is in the expected place on disk and that the 2798 * block has been mapped. 2799 */ 2800 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 2801 match = 1; 2802 done: 2803 BUF_UNLOCK(bpa); 2804 return (match); 2805 } 2806 2807 /* 2808 * vfs_bio_awrite: 2809 * 2810 * Implement clustered async writes for clearing out B_DELWRI buffers. 2811 * This is much better then the old way of writing only one buffer at 2812 * a time. Note that we may not be presented with the buffers in the 2813 * correct order, so we search for the cluster in both directions. 2814 */ 2815 int 2816 vfs_bio_awrite(struct buf *bp) 2817 { 2818 struct bufobj *bo; 2819 int i; 2820 int j; 2821 daddr_t lblkno = bp->b_lblkno; 2822 struct vnode *vp = bp->b_vp; 2823 int ncl; 2824 int nwritten; 2825 int size; 2826 int maxcl; 2827 int gbflags; 2828 2829 bo = &vp->v_bufobj; 2830 gbflags = (bp->b_data == unmapped_buf) ? GB_UNMAPPED : 0; 2831 /* 2832 * right now we support clustered writing only to regular files. If 2833 * we find a clusterable block we could be in the middle of a cluster 2834 * rather then at the beginning. 2835 */ 2836 if ((vp->v_type == VREG) && 2837 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 2838 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 2839 2840 size = vp->v_mount->mnt_stat.f_iosize; 2841 maxcl = MAXPHYS / size; 2842 2843 BO_RLOCK(bo); 2844 for (i = 1; i < maxcl; i++) 2845 if (vfs_bio_clcheck(vp, size, lblkno + i, 2846 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 2847 break; 2848 2849 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 2850 if (vfs_bio_clcheck(vp, size, lblkno - j, 2851 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 2852 break; 2853 BO_RUNLOCK(bo); 2854 --j; 2855 ncl = i + j; 2856 /* 2857 * this is a possible cluster write 2858 */ 2859 if (ncl != 1) { 2860 BUF_UNLOCK(bp); 2861 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl, 2862 gbflags); 2863 return (nwritten); 2864 } 2865 } 2866 bremfree(bp); 2867 bp->b_flags |= B_ASYNC; 2868 /* 2869 * default (old) behavior, writing out only one block 2870 * 2871 * XXX returns b_bufsize instead of b_bcount for nwritten? 2872 */ 2873 nwritten = bp->b_bufsize; 2874 (void) bwrite(bp); 2875 2876 return (nwritten); 2877 } 2878 2879 /* 2880 * getnewbuf_kva: 2881 * 2882 * Allocate KVA for an empty buf header according to gbflags. 2883 */ 2884 static int 2885 getnewbuf_kva(struct buf *bp, int gbflags, int maxsize) 2886 { 2887 2888 if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_UNMAPPED) { 2889 /* 2890 * In order to keep fragmentation sane we only allocate kva 2891 * in BKVASIZE chunks. XXX with vmem we can do page size. 2892 */ 2893 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2894 2895 if (maxsize != bp->b_kvasize && 2896 bufkva_alloc(bp, maxsize, gbflags)) 2897 return (ENOSPC); 2898 } 2899 return (0); 2900 } 2901 2902 /* 2903 * getnewbuf: 2904 * 2905 * Find and initialize a new buffer header, freeing up existing buffers 2906 * in the bufqueues as necessary. The new buffer is returned locked. 2907 * 2908 * We block if: 2909 * We have insufficient buffer headers 2910 * We have insufficient buffer space 2911 * buffer_arena is too fragmented ( space reservation fails ) 2912 * If we have to flush dirty buffers ( but we try to avoid this ) 2913 * 2914 * The caller is responsible for releasing the reserved bufspace after 2915 * allocbuf() is called. 2916 */ 2917 static struct buf * 2918 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int maxsize, int gbflags) 2919 { 2920 struct buf *bp; 2921 bool metadata, reserved; 2922 2923 bp = NULL; 2924 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 2925 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 2926 if (!unmapped_buf_allowed) 2927 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC); 2928 2929 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 || 2930 vp->v_type == VCHR) 2931 metadata = true; 2932 else 2933 metadata = false; 2934 atomic_add_int(&getnewbufcalls, 1); 2935 reserved = false; 2936 do { 2937 if (reserved == false && 2938 bufspace_reserve(maxsize, metadata) != 0) 2939 continue; 2940 reserved = true; 2941 if ((bp = buf_alloc()) == NULL) 2942 continue; 2943 if (getnewbuf_kva(bp, gbflags, maxsize) == 0) 2944 return (bp); 2945 break; 2946 } while(buf_scan(false) == 0); 2947 2948 if (reserved) 2949 atomic_subtract_long(&bufspace, maxsize); 2950 if (bp != NULL) { 2951 bp->b_flags |= B_INVAL; 2952 brelse(bp); 2953 } 2954 bufspace_wait(vp, gbflags, slpflag, slptimeo); 2955 2956 return (NULL); 2957 } 2958 2959 /* 2960 * buf_daemon: 2961 * 2962 * buffer flushing daemon. Buffers are normally flushed by the 2963 * update daemon but if it cannot keep up this process starts to 2964 * take the load in an attempt to prevent getnewbuf() from blocking. 2965 */ 2966 static struct kproc_desc buf_kp = { 2967 "bufdaemon", 2968 buf_daemon, 2969 &bufdaemonproc 2970 }; 2971 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 2972 2973 static int 2974 buf_flush(struct vnode *vp, int target) 2975 { 2976 int flushed; 2977 2978 flushed = flushbufqueues(vp, target, 0); 2979 if (flushed == 0) { 2980 /* 2981 * Could not find any buffers without rollback 2982 * dependencies, so just write the first one 2983 * in the hopes of eventually making progress. 2984 */ 2985 if (vp != NULL && target > 2) 2986 target /= 2; 2987 flushbufqueues(vp, target, 1); 2988 } 2989 return (flushed); 2990 } 2991 2992 static void 2993 buf_daemon() 2994 { 2995 int lodirty; 2996 2997 /* 2998 * This process needs to be suspended prior to shutdown sync. 2999 */ 3000 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 3001 SHUTDOWN_PRI_LAST); 3002 3003 /* 3004 * This process is allowed to take the buffer cache to the limit 3005 */ 3006 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 3007 mtx_lock(&bdlock); 3008 for (;;) { 3009 bd_request = 0; 3010 mtx_unlock(&bdlock); 3011 3012 kproc_suspend_check(bufdaemonproc); 3013 lodirty = lodirtybuffers; 3014 if (bd_speedupreq) { 3015 lodirty = numdirtybuffers / 2; 3016 bd_speedupreq = 0; 3017 } 3018 /* 3019 * Do the flush. Limit the amount of in-transit I/O we 3020 * allow to build up, otherwise we would completely saturate 3021 * the I/O system. 3022 */ 3023 while (numdirtybuffers > lodirty) { 3024 if (buf_flush(NULL, numdirtybuffers - lodirty) == 0) 3025 break; 3026 kern_yield(PRI_USER); 3027 } 3028 3029 /* 3030 * Only clear bd_request if we have reached our low water 3031 * mark. The buf_daemon normally waits 1 second and 3032 * then incrementally flushes any dirty buffers that have 3033 * built up, within reason. 3034 * 3035 * If we were unable to hit our low water mark and couldn't 3036 * find any flushable buffers, we sleep for a short period 3037 * to avoid endless loops on unlockable buffers. 3038 */ 3039 mtx_lock(&bdlock); 3040 if (numdirtybuffers <= lodirtybuffers) { 3041 /* 3042 * We reached our low water mark, reset the 3043 * request and sleep until we are needed again. 3044 * The sleep is just so the suspend code works. 3045 */ 3046 bd_request = 0; 3047 /* 3048 * Do an extra wakeup in case dirty threshold 3049 * changed via sysctl and the explicit transition 3050 * out of shortfall was missed. 3051 */ 3052 bdirtywakeup(); 3053 if (runningbufspace <= lorunningspace) 3054 runningwakeup(); 3055 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 3056 } else { 3057 /* 3058 * We couldn't find any flushable dirty buffers but 3059 * still have too many dirty buffers, we 3060 * have to sleep and try again. (rare) 3061 */ 3062 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 3063 } 3064 } 3065 } 3066 3067 /* 3068 * flushbufqueues: 3069 * 3070 * Try to flush a buffer in the dirty queue. We must be careful to 3071 * free up B_INVAL buffers instead of write them, which NFS is 3072 * particularly sensitive to. 3073 */ 3074 static int flushwithdeps = 0; 3075 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 3076 0, "Number of buffers flushed with dependecies that require rollbacks"); 3077 3078 static int 3079 flushbufqueues(struct vnode *lvp, int target, int flushdeps) 3080 { 3081 struct buf *sentinel; 3082 struct vnode *vp; 3083 struct mount *mp; 3084 struct buf *bp; 3085 int hasdeps; 3086 int flushed; 3087 int queue; 3088 int error; 3089 bool unlock; 3090 3091 flushed = 0; 3092 queue = QUEUE_DIRTY; 3093 bp = NULL; 3094 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 3095 sentinel->b_qindex = QUEUE_SENTINEL; 3096 mtx_lock(&bqlocks[queue]); 3097 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist); 3098 mtx_unlock(&bqlocks[queue]); 3099 while (flushed != target) { 3100 maybe_yield(); 3101 mtx_lock(&bqlocks[queue]); 3102 bp = TAILQ_NEXT(sentinel, b_freelist); 3103 if (bp != NULL) { 3104 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 3105 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel, 3106 b_freelist); 3107 } else { 3108 mtx_unlock(&bqlocks[queue]); 3109 break; 3110 } 3111 /* 3112 * Skip sentinels inserted by other invocations of the 3113 * flushbufqueues(), taking care to not reorder them. 3114 * 3115 * Only flush the buffers that belong to the 3116 * vnode locked by the curthread. 3117 */ 3118 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL && 3119 bp->b_vp != lvp)) { 3120 mtx_unlock(&bqlocks[queue]); 3121 continue; 3122 } 3123 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL); 3124 mtx_unlock(&bqlocks[queue]); 3125 if (error != 0) 3126 continue; 3127 if (bp->b_pin_count > 0) { 3128 BUF_UNLOCK(bp); 3129 continue; 3130 } 3131 /* 3132 * BKGRDINPROG can only be set with the buf and bufobj 3133 * locks both held. We tolerate a race to clear it here. 3134 */ 3135 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 3136 (bp->b_flags & B_DELWRI) == 0) { 3137 BUF_UNLOCK(bp); 3138 continue; 3139 } 3140 if (bp->b_flags & B_INVAL) { 3141 bremfreef(bp); 3142 brelse(bp); 3143 flushed++; 3144 continue; 3145 } 3146 3147 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 3148 if (flushdeps == 0) { 3149 BUF_UNLOCK(bp); 3150 continue; 3151 } 3152 hasdeps = 1; 3153 } else 3154 hasdeps = 0; 3155 /* 3156 * We must hold the lock on a vnode before writing 3157 * one of its buffers. Otherwise we may confuse, or 3158 * in the case of a snapshot vnode, deadlock the 3159 * system. 3160 * 3161 * The lock order here is the reverse of the normal 3162 * of vnode followed by buf lock. This is ok because 3163 * the NOWAIT will prevent deadlock. 3164 */ 3165 vp = bp->b_vp; 3166 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 3167 BUF_UNLOCK(bp); 3168 continue; 3169 } 3170 if (lvp == NULL) { 3171 unlock = true; 3172 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT); 3173 } else { 3174 ASSERT_VOP_LOCKED(vp, "getbuf"); 3175 unlock = false; 3176 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 : 3177 vn_lock(vp, LK_TRYUPGRADE); 3178 } 3179 if (error == 0) { 3180 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 3181 bp, bp->b_vp, bp->b_flags); 3182 if (curproc == bufdaemonproc) { 3183 vfs_bio_awrite(bp); 3184 } else { 3185 bremfree(bp); 3186 bwrite(bp); 3187 notbufdflushes++; 3188 } 3189 vn_finished_write(mp); 3190 if (unlock) 3191 VOP_UNLOCK(vp, 0); 3192 flushwithdeps += hasdeps; 3193 flushed++; 3194 3195 /* 3196 * Sleeping on runningbufspace while holding 3197 * vnode lock leads to deadlock. 3198 */ 3199 if (curproc == bufdaemonproc && 3200 runningbufspace > hirunningspace) 3201 waitrunningbufspace(); 3202 continue; 3203 } 3204 vn_finished_write(mp); 3205 BUF_UNLOCK(bp); 3206 } 3207 mtx_lock(&bqlocks[queue]); 3208 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 3209 mtx_unlock(&bqlocks[queue]); 3210 free(sentinel, M_TEMP); 3211 return (flushed); 3212 } 3213 3214 /* 3215 * Check to see if a block is currently memory resident. 3216 */ 3217 struct buf * 3218 incore(struct bufobj *bo, daddr_t blkno) 3219 { 3220 struct buf *bp; 3221 3222 BO_RLOCK(bo); 3223 bp = gbincore(bo, blkno); 3224 BO_RUNLOCK(bo); 3225 return (bp); 3226 } 3227 3228 /* 3229 * Returns true if no I/O is needed to access the 3230 * associated VM object. This is like incore except 3231 * it also hunts around in the VM system for the data. 3232 */ 3233 3234 static int 3235 inmem(struct vnode * vp, daddr_t blkno) 3236 { 3237 vm_object_t obj; 3238 vm_offset_t toff, tinc, size; 3239 vm_page_t m; 3240 vm_ooffset_t off; 3241 3242 ASSERT_VOP_LOCKED(vp, "inmem"); 3243 3244 if (incore(&vp->v_bufobj, blkno)) 3245 return 1; 3246 if (vp->v_mount == NULL) 3247 return 0; 3248 obj = vp->v_object; 3249 if (obj == NULL) 3250 return (0); 3251 3252 size = PAGE_SIZE; 3253 if (size > vp->v_mount->mnt_stat.f_iosize) 3254 size = vp->v_mount->mnt_stat.f_iosize; 3255 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 3256 3257 VM_OBJECT_RLOCK(obj); 3258 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 3259 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 3260 if (!m) 3261 goto notinmem; 3262 tinc = size; 3263 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 3264 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 3265 if (vm_page_is_valid(m, 3266 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 3267 goto notinmem; 3268 } 3269 VM_OBJECT_RUNLOCK(obj); 3270 return 1; 3271 3272 notinmem: 3273 VM_OBJECT_RUNLOCK(obj); 3274 return (0); 3275 } 3276 3277 /* 3278 * Set the dirty range for a buffer based on the status of the dirty 3279 * bits in the pages comprising the buffer. The range is limited 3280 * to the size of the buffer. 3281 * 3282 * Tell the VM system that the pages associated with this buffer 3283 * are clean. This is used for delayed writes where the data is 3284 * going to go to disk eventually without additional VM intevention. 3285 * 3286 * Note that while we only really need to clean through to b_bcount, we 3287 * just go ahead and clean through to b_bufsize. 3288 */ 3289 static void 3290 vfs_clean_pages_dirty_buf(struct buf *bp) 3291 { 3292 vm_ooffset_t foff, noff, eoff; 3293 vm_page_t m; 3294 int i; 3295 3296 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 3297 return; 3298 3299 foff = bp->b_offset; 3300 KASSERT(bp->b_offset != NOOFFSET, 3301 ("vfs_clean_pages_dirty_buf: no buffer offset")); 3302 3303 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 3304 vfs_drain_busy_pages(bp); 3305 vfs_setdirty_locked_object(bp); 3306 for (i = 0; i < bp->b_npages; i++) { 3307 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3308 eoff = noff; 3309 if (eoff > bp->b_offset + bp->b_bufsize) 3310 eoff = bp->b_offset + bp->b_bufsize; 3311 m = bp->b_pages[i]; 3312 vfs_page_set_validclean(bp, foff, m); 3313 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3314 foff = noff; 3315 } 3316 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 3317 } 3318 3319 static void 3320 vfs_setdirty_locked_object(struct buf *bp) 3321 { 3322 vm_object_t object; 3323 int i; 3324 3325 object = bp->b_bufobj->bo_object; 3326 VM_OBJECT_ASSERT_WLOCKED(object); 3327 3328 /* 3329 * We qualify the scan for modified pages on whether the 3330 * object has been flushed yet. 3331 */ 3332 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) { 3333 vm_offset_t boffset; 3334 vm_offset_t eoffset; 3335 3336 /* 3337 * test the pages to see if they have been modified directly 3338 * by users through the VM system. 3339 */ 3340 for (i = 0; i < bp->b_npages; i++) 3341 vm_page_test_dirty(bp->b_pages[i]); 3342 3343 /* 3344 * Calculate the encompassing dirty range, boffset and eoffset, 3345 * (eoffset - boffset) bytes. 3346 */ 3347 3348 for (i = 0; i < bp->b_npages; i++) { 3349 if (bp->b_pages[i]->dirty) 3350 break; 3351 } 3352 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3353 3354 for (i = bp->b_npages - 1; i >= 0; --i) { 3355 if (bp->b_pages[i]->dirty) { 3356 break; 3357 } 3358 } 3359 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3360 3361 /* 3362 * Fit it to the buffer. 3363 */ 3364 3365 if (eoffset > bp->b_bcount) 3366 eoffset = bp->b_bcount; 3367 3368 /* 3369 * If we have a good dirty range, merge with the existing 3370 * dirty range. 3371 */ 3372 3373 if (boffset < eoffset) { 3374 if (bp->b_dirtyoff > boffset) 3375 bp->b_dirtyoff = boffset; 3376 if (bp->b_dirtyend < eoffset) 3377 bp->b_dirtyend = eoffset; 3378 } 3379 } 3380 } 3381 3382 /* 3383 * Allocate the KVA mapping for an existing buffer. 3384 * If an unmapped buffer is provided but a mapped buffer is requested, take 3385 * also care to properly setup mappings between pages and KVA. 3386 */ 3387 static void 3388 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags) 3389 { 3390 int bsize, maxsize, need_mapping, need_kva; 3391 off_t offset; 3392 3393 need_mapping = bp->b_data == unmapped_buf && 3394 (gbflags & GB_UNMAPPED) == 0; 3395 need_kva = bp->b_kvabase == unmapped_buf && 3396 bp->b_data == unmapped_buf && 3397 (gbflags & GB_KVAALLOC) != 0; 3398 if (!need_mapping && !need_kva) 3399 return; 3400 3401 BUF_CHECK_UNMAPPED(bp); 3402 3403 if (need_mapping && bp->b_kvabase != unmapped_buf) { 3404 /* 3405 * Buffer is not mapped, but the KVA was already 3406 * reserved at the time of the instantiation. Use the 3407 * allocated space. 3408 */ 3409 goto has_addr; 3410 } 3411 3412 /* 3413 * Calculate the amount of the address space we would reserve 3414 * if the buffer was mapped. 3415 */ 3416 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize; 3417 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3418 offset = blkno * bsize; 3419 maxsize = size + (offset & PAGE_MASK); 3420 maxsize = imax(maxsize, bsize); 3421 3422 while (bufkva_alloc(bp, maxsize, gbflags) != 0) { 3423 if ((gbflags & GB_NOWAIT_BD) != 0) { 3424 /* 3425 * XXXKIB: defragmentation cannot 3426 * succeed, not sure what else to do. 3427 */ 3428 panic("GB_NOWAIT_BD and GB_UNMAPPED %p", bp); 3429 } 3430 atomic_add_int(&mappingrestarts, 1); 3431 bufspace_wait(bp->b_vp, gbflags, 0, 0); 3432 } 3433 has_addr: 3434 if (need_mapping) { 3435 /* b_offset is handled by bpmap_qenter. */ 3436 bp->b_data = bp->b_kvabase; 3437 BUF_CHECK_MAPPED(bp); 3438 bpmap_qenter(bp); 3439 } 3440 } 3441 3442 /* 3443 * getblk: 3444 * 3445 * Get a block given a specified block and offset into a file/device. 3446 * The buffers B_DONE bit will be cleared on return, making it almost 3447 * ready for an I/O initiation. B_INVAL may or may not be set on 3448 * return. The caller should clear B_INVAL prior to initiating a 3449 * READ. 3450 * 3451 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 3452 * an existing buffer. 3453 * 3454 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 3455 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 3456 * and then cleared based on the backing VM. If the previous buffer is 3457 * non-0-sized but invalid, B_CACHE will be cleared. 3458 * 3459 * If getblk() must create a new buffer, the new buffer is returned with 3460 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 3461 * case it is returned with B_INVAL clear and B_CACHE set based on the 3462 * backing VM. 3463 * 3464 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 3465 * B_CACHE bit is clear. 3466 * 3467 * What this means, basically, is that the caller should use B_CACHE to 3468 * determine whether the buffer is fully valid or not and should clear 3469 * B_INVAL prior to issuing a read. If the caller intends to validate 3470 * the buffer by loading its data area with something, the caller needs 3471 * to clear B_INVAL. If the caller does this without issuing an I/O, 3472 * the caller should set B_CACHE ( as an optimization ), else the caller 3473 * should issue the I/O and biodone() will set B_CACHE if the I/O was 3474 * a write attempt or if it was a successfull read. If the caller 3475 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 3476 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 3477 */ 3478 struct buf * 3479 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3480 int flags) 3481 { 3482 struct buf *bp; 3483 struct bufobj *bo; 3484 int bsize, error, maxsize, vmio; 3485 off_t offset; 3486 3487 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 3488 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3489 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3490 ASSERT_VOP_LOCKED(vp, "getblk"); 3491 if (size > MAXBCACHEBUF) 3492 panic("getblk: size(%d) > MAXBCACHEBUF(%d)\n", size, 3493 MAXBCACHEBUF); 3494 if (!unmapped_buf_allowed) 3495 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3496 3497 bo = &vp->v_bufobj; 3498 loop: 3499 BO_RLOCK(bo); 3500 bp = gbincore(bo, blkno); 3501 if (bp != NULL) { 3502 int lockflags; 3503 /* 3504 * Buffer is in-core. If the buffer is not busy nor managed, 3505 * it must be on a queue. 3506 */ 3507 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 3508 3509 if (flags & GB_LOCK_NOWAIT) 3510 lockflags |= LK_NOWAIT; 3511 3512 error = BUF_TIMELOCK(bp, lockflags, 3513 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo); 3514 3515 /* 3516 * If we slept and got the lock we have to restart in case 3517 * the buffer changed identities. 3518 */ 3519 if (error == ENOLCK) 3520 goto loop; 3521 /* We timed out or were interrupted. */ 3522 else if (error) 3523 return (NULL); 3524 /* If recursed, assume caller knows the rules. */ 3525 else if (BUF_LOCKRECURSED(bp)) 3526 goto end; 3527 3528 /* 3529 * The buffer is locked. B_CACHE is cleared if the buffer is 3530 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 3531 * and for a VMIO buffer B_CACHE is adjusted according to the 3532 * backing VM cache. 3533 */ 3534 if (bp->b_flags & B_INVAL) 3535 bp->b_flags &= ~B_CACHE; 3536 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 3537 bp->b_flags |= B_CACHE; 3538 if (bp->b_flags & B_MANAGED) 3539 MPASS(bp->b_qindex == QUEUE_NONE); 3540 else 3541 bremfree(bp); 3542 3543 /* 3544 * check for size inconsistencies for non-VMIO case. 3545 */ 3546 if (bp->b_bcount != size) { 3547 if ((bp->b_flags & B_VMIO) == 0 || 3548 (size > bp->b_kvasize)) { 3549 if (bp->b_flags & B_DELWRI) { 3550 /* 3551 * If buffer is pinned and caller does 3552 * not want sleep waiting for it to be 3553 * unpinned, bail out 3554 * */ 3555 if (bp->b_pin_count > 0) { 3556 if (flags & GB_LOCK_NOWAIT) { 3557 bqrelse(bp); 3558 return (NULL); 3559 } else { 3560 bunpin_wait(bp); 3561 } 3562 } 3563 bp->b_flags |= B_NOCACHE; 3564 bwrite(bp); 3565 } else { 3566 if (LIST_EMPTY(&bp->b_dep)) { 3567 bp->b_flags |= B_RELBUF; 3568 brelse(bp); 3569 } else { 3570 bp->b_flags |= B_NOCACHE; 3571 bwrite(bp); 3572 } 3573 } 3574 goto loop; 3575 } 3576 } 3577 3578 /* 3579 * Handle the case of unmapped buffer which should 3580 * become mapped, or the buffer for which KVA 3581 * reservation is requested. 3582 */ 3583 bp_unmapped_get_kva(bp, blkno, size, flags); 3584 3585 /* 3586 * If the size is inconsistant in the VMIO case, we can resize 3587 * the buffer. This might lead to B_CACHE getting set or 3588 * cleared. If the size has not changed, B_CACHE remains 3589 * unchanged from its previous state. 3590 */ 3591 allocbuf(bp, size); 3592 3593 KASSERT(bp->b_offset != NOOFFSET, 3594 ("getblk: no buffer offset")); 3595 3596 /* 3597 * A buffer with B_DELWRI set and B_CACHE clear must 3598 * be committed before we can return the buffer in 3599 * order to prevent the caller from issuing a read 3600 * ( due to B_CACHE not being set ) and overwriting 3601 * it. 3602 * 3603 * Most callers, including NFS and FFS, need this to 3604 * operate properly either because they assume they 3605 * can issue a read if B_CACHE is not set, or because 3606 * ( for example ) an uncached B_DELWRI might loop due 3607 * to softupdates re-dirtying the buffer. In the latter 3608 * case, B_CACHE is set after the first write completes, 3609 * preventing further loops. 3610 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 3611 * above while extending the buffer, we cannot allow the 3612 * buffer to remain with B_CACHE set after the write 3613 * completes or it will represent a corrupt state. To 3614 * deal with this we set B_NOCACHE to scrap the buffer 3615 * after the write. 3616 * 3617 * We might be able to do something fancy, like setting 3618 * B_CACHE in bwrite() except if B_DELWRI is already set, 3619 * so the below call doesn't set B_CACHE, but that gets real 3620 * confusing. This is much easier. 3621 */ 3622 3623 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 3624 bp->b_flags |= B_NOCACHE; 3625 bwrite(bp); 3626 goto loop; 3627 } 3628 bp->b_flags &= ~B_DONE; 3629 } else { 3630 /* 3631 * Buffer is not in-core, create new buffer. The buffer 3632 * returned by getnewbuf() is locked. Note that the returned 3633 * buffer is also considered valid (not marked B_INVAL). 3634 */ 3635 BO_RUNLOCK(bo); 3636 /* 3637 * If the user does not want us to create the buffer, bail out 3638 * here. 3639 */ 3640 if (flags & GB_NOCREAT) 3641 return NULL; 3642 if (numfreebuffers == 0 && TD_IS_IDLETHREAD(curthread)) 3643 return NULL; 3644 3645 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize; 3646 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3647 offset = blkno * bsize; 3648 vmio = vp->v_object != NULL; 3649 if (vmio) { 3650 maxsize = size + (offset & PAGE_MASK); 3651 } else { 3652 maxsize = size; 3653 /* Do not allow non-VMIO notmapped buffers. */ 3654 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3655 } 3656 maxsize = imax(maxsize, bsize); 3657 3658 bp = getnewbuf(vp, slpflag, slptimeo, maxsize, flags); 3659 if (bp == NULL) { 3660 if (slpflag || slptimeo) 3661 return NULL; 3662 /* 3663 * XXX This is here until the sleep path is diagnosed 3664 * enough to work under very low memory conditions. 3665 * 3666 * There's an issue on low memory, 4BSD+non-preempt 3667 * systems (eg MIPS routers with 32MB RAM) where buffer 3668 * exhaustion occurs without sleeping for buffer 3669 * reclaimation. This just sticks in a loop and 3670 * constantly attempts to allocate a buffer, which 3671 * hits exhaustion and tries to wakeup bufdaemon. 3672 * This never happens because we never yield. 3673 * 3674 * The real solution is to identify and fix these cases 3675 * so we aren't effectively busy-waiting in a loop 3676 * until the reclaimation path has cycles to run. 3677 */ 3678 kern_yield(PRI_USER); 3679 goto loop; 3680 } 3681 3682 /* 3683 * This code is used to make sure that a buffer is not 3684 * created while the getnewbuf routine is blocked. 3685 * This can be a problem whether the vnode is locked or not. 3686 * If the buffer is created out from under us, we have to 3687 * throw away the one we just created. 3688 * 3689 * Note: this must occur before we associate the buffer 3690 * with the vp especially considering limitations in 3691 * the splay tree implementation when dealing with duplicate 3692 * lblkno's. 3693 */ 3694 BO_LOCK(bo); 3695 if (gbincore(bo, blkno)) { 3696 BO_UNLOCK(bo); 3697 bp->b_flags |= B_INVAL; 3698 brelse(bp); 3699 bufspace_release(maxsize); 3700 goto loop; 3701 } 3702 3703 /* 3704 * Insert the buffer into the hash, so that it can 3705 * be found by incore. 3706 */ 3707 bp->b_blkno = bp->b_lblkno = blkno; 3708 bp->b_offset = offset; 3709 bgetvp(vp, bp); 3710 BO_UNLOCK(bo); 3711 3712 /* 3713 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 3714 * buffer size starts out as 0, B_CACHE will be set by 3715 * allocbuf() for the VMIO case prior to it testing the 3716 * backing store for validity. 3717 */ 3718 3719 if (vmio) { 3720 bp->b_flags |= B_VMIO; 3721 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 3722 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 3723 bp, vp->v_object, bp->b_bufobj->bo_object)); 3724 } else { 3725 bp->b_flags &= ~B_VMIO; 3726 KASSERT(bp->b_bufobj->bo_object == NULL, 3727 ("ARGH! has b_bufobj->bo_object %p %p\n", 3728 bp, bp->b_bufobj->bo_object)); 3729 BUF_CHECK_MAPPED(bp); 3730 } 3731 3732 allocbuf(bp, size); 3733 bufspace_release(maxsize); 3734 bp->b_flags &= ~B_DONE; 3735 } 3736 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 3737 BUF_ASSERT_HELD(bp); 3738 end: 3739 KASSERT(bp->b_bufobj == bo, 3740 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 3741 return (bp); 3742 } 3743 3744 /* 3745 * Get an empty, disassociated buffer of given size. The buffer is initially 3746 * set to B_INVAL. 3747 */ 3748 struct buf * 3749 geteblk(int size, int flags) 3750 { 3751 struct buf *bp; 3752 int maxsize; 3753 3754 maxsize = (size + BKVAMASK) & ~BKVAMASK; 3755 while ((bp = getnewbuf(NULL, 0, 0, maxsize, flags)) == NULL) { 3756 if ((flags & GB_NOWAIT_BD) && 3757 (curthread->td_pflags & TDP_BUFNEED) != 0) 3758 return (NULL); 3759 } 3760 allocbuf(bp, size); 3761 bufspace_release(maxsize); 3762 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 3763 BUF_ASSERT_HELD(bp); 3764 return (bp); 3765 } 3766 3767 /* 3768 * Truncate the backing store for a non-vmio buffer. 3769 */ 3770 static void 3771 vfs_nonvmio_truncate(struct buf *bp, int newbsize) 3772 { 3773 3774 if (bp->b_flags & B_MALLOC) { 3775 /* 3776 * malloced buffers are not shrunk 3777 */ 3778 if (newbsize == 0) { 3779 bufmallocadjust(bp, 0); 3780 free(bp->b_data, M_BIOBUF); 3781 bp->b_data = bp->b_kvabase; 3782 bp->b_flags &= ~B_MALLOC; 3783 } 3784 return; 3785 } 3786 vm_hold_free_pages(bp, newbsize); 3787 bufspace_adjust(bp, newbsize); 3788 } 3789 3790 /* 3791 * Extend the backing for a non-VMIO buffer. 3792 */ 3793 static void 3794 vfs_nonvmio_extend(struct buf *bp, int newbsize) 3795 { 3796 caddr_t origbuf; 3797 int origbufsize; 3798 3799 /* 3800 * We only use malloced memory on the first allocation. 3801 * and revert to page-allocated memory when the buffer 3802 * grows. 3803 * 3804 * There is a potential smp race here that could lead 3805 * to bufmallocspace slightly passing the max. It 3806 * is probably extremely rare and not worth worrying 3807 * over. 3808 */ 3809 if (bp->b_bufsize == 0 && newbsize <= PAGE_SIZE/2 && 3810 bufmallocspace < maxbufmallocspace) { 3811 bp->b_data = malloc(newbsize, M_BIOBUF, M_WAITOK); 3812 bp->b_flags |= B_MALLOC; 3813 bufmallocadjust(bp, newbsize); 3814 return; 3815 } 3816 3817 /* 3818 * If the buffer is growing on its other-than-first 3819 * allocation then we revert to the page-allocation 3820 * scheme. 3821 */ 3822 origbuf = NULL; 3823 origbufsize = 0; 3824 if (bp->b_flags & B_MALLOC) { 3825 origbuf = bp->b_data; 3826 origbufsize = bp->b_bufsize; 3827 bp->b_data = bp->b_kvabase; 3828 bufmallocadjust(bp, 0); 3829 bp->b_flags &= ~B_MALLOC; 3830 newbsize = round_page(newbsize); 3831 } 3832 vm_hold_load_pages(bp, (vm_offset_t) bp->b_data + bp->b_bufsize, 3833 (vm_offset_t) bp->b_data + newbsize); 3834 if (origbuf != NULL) { 3835 bcopy(origbuf, bp->b_data, origbufsize); 3836 free(origbuf, M_BIOBUF); 3837 } 3838 bufspace_adjust(bp, newbsize); 3839 } 3840 3841 /* 3842 * This code constitutes the buffer memory from either anonymous system 3843 * memory (in the case of non-VMIO operations) or from an associated 3844 * VM object (in the case of VMIO operations). This code is able to 3845 * resize a buffer up or down. 3846 * 3847 * Note that this code is tricky, and has many complications to resolve 3848 * deadlock or inconsistant data situations. Tread lightly!!! 3849 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 3850 * the caller. Calling this code willy nilly can result in the loss of data. 3851 * 3852 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 3853 * B_CACHE for the non-VMIO case. 3854 */ 3855 int 3856 allocbuf(struct buf *bp, int size) 3857 { 3858 int newbsize; 3859 3860 BUF_ASSERT_HELD(bp); 3861 3862 if (bp->b_bcount == size) 3863 return (1); 3864 3865 if (bp->b_kvasize != 0 && bp->b_kvasize < size) 3866 panic("allocbuf: buffer too small"); 3867 3868 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3869 if ((bp->b_flags & B_VMIO) == 0) { 3870 if ((bp->b_flags & B_MALLOC) == 0) 3871 newbsize = round_page(newbsize); 3872 /* 3873 * Just get anonymous memory from the kernel. Don't 3874 * mess with B_CACHE. 3875 */ 3876 if (newbsize < bp->b_bufsize) 3877 vfs_nonvmio_truncate(bp, newbsize); 3878 else if (newbsize > bp->b_bufsize) 3879 vfs_nonvmio_extend(bp, newbsize); 3880 } else { 3881 int desiredpages; 3882 3883 desiredpages = (size == 0) ? 0 : 3884 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 3885 3886 if (bp->b_flags & B_MALLOC) 3887 panic("allocbuf: VMIO buffer can't be malloced"); 3888 /* 3889 * Set B_CACHE initially if buffer is 0 length or will become 3890 * 0-length. 3891 */ 3892 if (size == 0 || bp->b_bufsize == 0) 3893 bp->b_flags |= B_CACHE; 3894 3895 if (newbsize < bp->b_bufsize) 3896 vfs_vmio_truncate(bp, desiredpages); 3897 /* XXX This looks as if it should be newbsize > b_bufsize */ 3898 else if (size > bp->b_bcount) 3899 vfs_vmio_extend(bp, desiredpages, size); 3900 bufspace_adjust(bp, newbsize); 3901 } 3902 bp->b_bcount = size; /* requested buffer size. */ 3903 return (1); 3904 } 3905 3906 extern int inflight_transient_maps; 3907 3908 void 3909 biodone(struct bio *bp) 3910 { 3911 struct mtx *mtxp; 3912 void (*done)(struct bio *); 3913 vm_offset_t start, end; 3914 3915 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) { 3916 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING; 3917 bp->bio_flags |= BIO_UNMAPPED; 3918 start = trunc_page((vm_offset_t)bp->bio_data); 3919 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length); 3920 bp->bio_data = unmapped_buf; 3921 pmap_qremove(start, OFF_TO_IDX(end - start)); 3922 vmem_free(transient_arena, start, end - start); 3923 atomic_add_int(&inflight_transient_maps, -1); 3924 } 3925 done = bp->bio_done; 3926 if (done == NULL) { 3927 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3928 mtx_lock(mtxp); 3929 bp->bio_flags |= BIO_DONE; 3930 wakeup(bp); 3931 mtx_unlock(mtxp); 3932 } else { 3933 bp->bio_flags |= BIO_DONE; 3934 done(bp); 3935 } 3936 } 3937 3938 /* 3939 * Wait for a BIO to finish. 3940 */ 3941 int 3942 biowait(struct bio *bp, const char *wchan) 3943 { 3944 struct mtx *mtxp; 3945 3946 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3947 mtx_lock(mtxp); 3948 while ((bp->bio_flags & BIO_DONE) == 0) 3949 msleep(bp, mtxp, PRIBIO, wchan, 0); 3950 mtx_unlock(mtxp); 3951 if (bp->bio_error != 0) 3952 return (bp->bio_error); 3953 if (!(bp->bio_flags & BIO_ERROR)) 3954 return (0); 3955 return (EIO); 3956 } 3957 3958 void 3959 biofinish(struct bio *bp, struct devstat *stat, int error) 3960 { 3961 3962 if (error) { 3963 bp->bio_error = error; 3964 bp->bio_flags |= BIO_ERROR; 3965 } 3966 if (stat != NULL) 3967 devstat_end_transaction_bio(stat, bp); 3968 biodone(bp); 3969 } 3970 3971 /* 3972 * bufwait: 3973 * 3974 * Wait for buffer I/O completion, returning error status. The buffer 3975 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3976 * error and cleared. 3977 */ 3978 int 3979 bufwait(struct buf *bp) 3980 { 3981 if (bp->b_iocmd == BIO_READ) 3982 bwait(bp, PRIBIO, "biord"); 3983 else 3984 bwait(bp, PRIBIO, "biowr"); 3985 if (bp->b_flags & B_EINTR) { 3986 bp->b_flags &= ~B_EINTR; 3987 return (EINTR); 3988 } 3989 if (bp->b_ioflags & BIO_ERROR) { 3990 return (bp->b_error ? bp->b_error : EIO); 3991 } else { 3992 return (0); 3993 } 3994 } 3995 3996 /* 3997 * bufdone: 3998 * 3999 * Finish I/O on a buffer, optionally calling a completion function. 4000 * This is usually called from an interrupt so process blocking is 4001 * not allowed. 4002 * 4003 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 4004 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 4005 * assuming B_INVAL is clear. 4006 * 4007 * For the VMIO case, we set B_CACHE if the op was a read and no 4008 * read error occured, or if the op was a write. B_CACHE is never 4009 * set if the buffer is invalid or otherwise uncacheable. 4010 * 4011 * biodone does not mess with B_INVAL, allowing the I/O routine or the 4012 * initiator to leave B_INVAL set to brelse the buffer out of existance 4013 * in the biodone routine. 4014 */ 4015 void 4016 bufdone(struct buf *bp) 4017 { 4018 struct bufobj *dropobj; 4019 void (*biodone)(struct buf *); 4020 4021 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 4022 dropobj = NULL; 4023 4024 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 4025 BUF_ASSERT_HELD(bp); 4026 4027 runningbufwakeup(bp); 4028 if (bp->b_iocmd == BIO_WRITE) 4029 dropobj = bp->b_bufobj; 4030 /* call optional completion function if requested */ 4031 if (bp->b_iodone != NULL) { 4032 biodone = bp->b_iodone; 4033 bp->b_iodone = NULL; 4034 (*biodone) (bp); 4035 if (dropobj) 4036 bufobj_wdrop(dropobj); 4037 return; 4038 } 4039 4040 bufdone_finish(bp); 4041 4042 if (dropobj) 4043 bufobj_wdrop(dropobj); 4044 } 4045 4046 void 4047 bufdone_finish(struct buf *bp) 4048 { 4049 BUF_ASSERT_HELD(bp); 4050 4051 if (!LIST_EMPTY(&bp->b_dep)) 4052 buf_complete(bp); 4053 4054 if (bp->b_flags & B_VMIO) { 4055 /* 4056 * Set B_CACHE if the op was a normal read and no error 4057 * occured. B_CACHE is set for writes in the b*write() 4058 * routines. 4059 */ 4060 if (bp->b_iocmd == BIO_READ && 4061 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 4062 !(bp->b_ioflags & BIO_ERROR)) 4063 bp->b_flags |= B_CACHE; 4064 vfs_vmio_iodone(bp); 4065 } 4066 4067 /* 4068 * For asynchronous completions, release the buffer now. The brelse 4069 * will do a wakeup there if necessary - so no need to do a wakeup 4070 * here in the async case. The sync case always needs to do a wakeup. 4071 */ 4072 if (bp->b_flags & B_ASYNC) { 4073 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || 4074 (bp->b_ioflags & BIO_ERROR)) 4075 brelse(bp); 4076 else 4077 bqrelse(bp); 4078 } else 4079 bdone(bp); 4080 } 4081 4082 /* 4083 * This routine is called in lieu of iodone in the case of 4084 * incomplete I/O. This keeps the busy status for pages 4085 * consistant. 4086 */ 4087 void 4088 vfs_unbusy_pages(struct buf *bp) 4089 { 4090 int i; 4091 vm_object_t obj; 4092 vm_page_t m; 4093 4094 runningbufwakeup(bp); 4095 if (!(bp->b_flags & B_VMIO)) 4096 return; 4097 4098 obj = bp->b_bufobj->bo_object; 4099 VM_OBJECT_WLOCK(obj); 4100 for (i = 0; i < bp->b_npages; i++) { 4101 m = bp->b_pages[i]; 4102 if (m == bogus_page) { 4103 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 4104 if (!m) 4105 panic("vfs_unbusy_pages: page missing\n"); 4106 bp->b_pages[i] = m; 4107 if (buf_mapped(bp)) { 4108 BUF_CHECK_MAPPED(bp); 4109 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4110 bp->b_pages, bp->b_npages); 4111 } else 4112 BUF_CHECK_UNMAPPED(bp); 4113 } 4114 vm_page_sunbusy(m); 4115 } 4116 vm_object_pip_wakeupn(obj, bp->b_npages); 4117 VM_OBJECT_WUNLOCK(obj); 4118 } 4119 4120 /* 4121 * vfs_page_set_valid: 4122 * 4123 * Set the valid bits in a page based on the supplied offset. The 4124 * range is restricted to the buffer's size. 4125 * 4126 * This routine is typically called after a read completes. 4127 */ 4128 static void 4129 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4130 { 4131 vm_ooffset_t eoff; 4132 4133 /* 4134 * Compute the end offset, eoff, such that [off, eoff) does not span a 4135 * page boundary and eoff is not greater than the end of the buffer. 4136 * The end of the buffer, in this case, is our file EOF, not the 4137 * allocation size of the buffer. 4138 */ 4139 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 4140 if (eoff > bp->b_offset + bp->b_bcount) 4141 eoff = bp->b_offset + bp->b_bcount; 4142 4143 /* 4144 * Set valid range. This is typically the entire buffer and thus the 4145 * entire page. 4146 */ 4147 if (eoff > off) 4148 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off); 4149 } 4150 4151 /* 4152 * vfs_page_set_validclean: 4153 * 4154 * Set the valid bits and clear the dirty bits in a page based on the 4155 * supplied offset. The range is restricted to the buffer's size. 4156 */ 4157 static void 4158 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4159 { 4160 vm_ooffset_t soff, eoff; 4161 4162 /* 4163 * Start and end offsets in buffer. eoff - soff may not cross a 4164 * page boundry or cross the end of the buffer. The end of the 4165 * buffer, in this case, is our file EOF, not the allocation size 4166 * of the buffer. 4167 */ 4168 soff = off; 4169 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4170 if (eoff > bp->b_offset + bp->b_bcount) 4171 eoff = bp->b_offset + bp->b_bcount; 4172 4173 /* 4174 * Set valid range. This is typically the entire buffer and thus the 4175 * entire page. 4176 */ 4177 if (eoff > soff) { 4178 vm_page_set_validclean( 4179 m, 4180 (vm_offset_t) (soff & PAGE_MASK), 4181 (vm_offset_t) (eoff - soff) 4182 ); 4183 } 4184 } 4185 4186 /* 4187 * Ensure that all buffer pages are not exclusive busied. If any page is 4188 * exclusive busy, drain it. 4189 */ 4190 void 4191 vfs_drain_busy_pages(struct buf *bp) 4192 { 4193 vm_page_t m; 4194 int i, last_busied; 4195 4196 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object); 4197 last_busied = 0; 4198 for (i = 0; i < bp->b_npages; i++) { 4199 m = bp->b_pages[i]; 4200 if (vm_page_xbusied(m)) { 4201 for (; last_busied < i; last_busied++) 4202 vm_page_sbusy(bp->b_pages[last_busied]); 4203 while (vm_page_xbusied(m)) { 4204 vm_page_lock(m); 4205 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4206 vm_page_busy_sleep(m, "vbpage"); 4207 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4208 } 4209 } 4210 } 4211 for (i = 0; i < last_busied; i++) 4212 vm_page_sunbusy(bp->b_pages[i]); 4213 } 4214 4215 /* 4216 * This routine is called before a device strategy routine. 4217 * It is used to tell the VM system that paging I/O is in 4218 * progress, and treat the pages associated with the buffer 4219 * almost as being exclusive busy. Also the object paging_in_progress 4220 * flag is handled to make sure that the object doesn't become 4221 * inconsistant. 4222 * 4223 * Since I/O has not been initiated yet, certain buffer flags 4224 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 4225 * and should be ignored. 4226 */ 4227 void 4228 vfs_busy_pages(struct buf *bp, int clear_modify) 4229 { 4230 int i, bogus; 4231 vm_object_t obj; 4232 vm_ooffset_t foff; 4233 vm_page_t m; 4234 4235 if (!(bp->b_flags & B_VMIO)) 4236 return; 4237 4238 obj = bp->b_bufobj->bo_object; 4239 foff = bp->b_offset; 4240 KASSERT(bp->b_offset != NOOFFSET, 4241 ("vfs_busy_pages: no buffer offset")); 4242 VM_OBJECT_WLOCK(obj); 4243 vfs_drain_busy_pages(bp); 4244 if (bp->b_bufsize != 0) 4245 vfs_setdirty_locked_object(bp); 4246 bogus = 0; 4247 for (i = 0; i < bp->b_npages; i++) { 4248 m = bp->b_pages[i]; 4249 4250 if ((bp->b_flags & B_CLUSTER) == 0) { 4251 vm_object_pip_add(obj, 1); 4252 vm_page_sbusy(m); 4253 } 4254 /* 4255 * When readying a buffer for a read ( i.e 4256 * clear_modify == 0 ), it is important to do 4257 * bogus_page replacement for valid pages in 4258 * partially instantiated buffers. Partially 4259 * instantiated buffers can, in turn, occur when 4260 * reconstituting a buffer from its VM backing store 4261 * base. We only have to do this if B_CACHE is 4262 * clear ( which causes the I/O to occur in the 4263 * first place ). The replacement prevents the read 4264 * I/O from overwriting potentially dirty VM-backed 4265 * pages. XXX bogus page replacement is, uh, bogus. 4266 * It may not work properly with small-block devices. 4267 * We need to find a better way. 4268 */ 4269 if (clear_modify) { 4270 pmap_remove_write(m); 4271 vfs_page_set_validclean(bp, foff, m); 4272 } else if (m->valid == VM_PAGE_BITS_ALL && 4273 (bp->b_flags & B_CACHE) == 0) { 4274 bp->b_pages[i] = bogus_page; 4275 bogus++; 4276 } 4277 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4278 } 4279 VM_OBJECT_WUNLOCK(obj); 4280 if (bogus && buf_mapped(bp)) { 4281 BUF_CHECK_MAPPED(bp); 4282 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4283 bp->b_pages, bp->b_npages); 4284 } 4285 } 4286 4287 /* 4288 * vfs_bio_set_valid: 4289 * 4290 * Set the range within the buffer to valid. The range is 4291 * relative to the beginning of the buffer, b_offset. Note that 4292 * b_offset itself may be offset from the beginning of the first 4293 * page. 4294 */ 4295 void 4296 vfs_bio_set_valid(struct buf *bp, int base, int size) 4297 { 4298 int i, n; 4299 vm_page_t m; 4300 4301 if (!(bp->b_flags & B_VMIO)) 4302 return; 4303 4304 /* 4305 * Fixup base to be relative to beginning of first page. 4306 * Set initial n to be the maximum number of bytes in the 4307 * first page that can be validated. 4308 */ 4309 base += (bp->b_offset & PAGE_MASK); 4310 n = PAGE_SIZE - (base & PAGE_MASK); 4311 4312 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4313 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4314 m = bp->b_pages[i]; 4315 if (n > size) 4316 n = size; 4317 vm_page_set_valid_range(m, base & PAGE_MASK, n); 4318 base += n; 4319 size -= n; 4320 n = PAGE_SIZE; 4321 } 4322 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4323 } 4324 4325 /* 4326 * vfs_bio_clrbuf: 4327 * 4328 * If the specified buffer is a non-VMIO buffer, clear the entire 4329 * buffer. If the specified buffer is a VMIO buffer, clear and 4330 * validate only the previously invalid portions of the buffer. 4331 * This routine essentially fakes an I/O, so we need to clear 4332 * BIO_ERROR and B_INVAL. 4333 * 4334 * Note that while we only theoretically need to clear through b_bcount, 4335 * we go ahead and clear through b_bufsize. 4336 */ 4337 void 4338 vfs_bio_clrbuf(struct buf *bp) 4339 { 4340 int i, j, mask, sa, ea, slide; 4341 4342 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 4343 clrbuf(bp); 4344 return; 4345 } 4346 bp->b_flags &= ~B_INVAL; 4347 bp->b_ioflags &= ~BIO_ERROR; 4348 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4349 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 4350 (bp->b_offset & PAGE_MASK) == 0) { 4351 if (bp->b_pages[0] == bogus_page) 4352 goto unlock; 4353 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 4354 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object); 4355 if ((bp->b_pages[0]->valid & mask) == mask) 4356 goto unlock; 4357 if ((bp->b_pages[0]->valid & mask) == 0) { 4358 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize); 4359 bp->b_pages[0]->valid |= mask; 4360 goto unlock; 4361 } 4362 } 4363 sa = bp->b_offset & PAGE_MASK; 4364 slide = 0; 4365 for (i = 0; i < bp->b_npages; i++, sa = 0) { 4366 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize); 4367 ea = slide & PAGE_MASK; 4368 if (ea == 0) 4369 ea = PAGE_SIZE; 4370 if (bp->b_pages[i] == bogus_page) 4371 continue; 4372 j = sa / DEV_BSIZE; 4373 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 4374 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object); 4375 if ((bp->b_pages[i]->valid & mask) == mask) 4376 continue; 4377 if ((bp->b_pages[i]->valid & mask) == 0) 4378 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa); 4379 else { 4380 for (; sa < ea; sa += DEV_BSIZE, j++) { 4381 if ((bp->b_pages[i]->valid & (1 << j)) == 0) { 4382 pmap_zero_page_area(bp->b_pages[i], 4383 sa, DEV_BSIZE); 4384 } 4385 } 4386 } 4387 bp->b_pages[i]->valid |= mask; 4388 } 4389 unlock: 4390 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4391 bp->b_resid = 0; 4392 } 4393 4394 void 4395 vfs_bio_bzero_buf(struct buf *bp, int base, int size) 4396 { 4397 vm_page_t m; 4398 int i, n; 4399 4400 if (buf_mapped(bp)) { 4401 BUF_CHECK_MAPPED(bp); 4402 bzero(bp->b_data + base, size); 4403 } else { 4404 BUF_CHECK_UNMAPPED(bp); 4405 n = PAGE_SIZE - (base & PAGE_MASK); 4406 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4407 m = bp->b_pages[i]; 4408 if (n > size) 4409 n = size; 4410 pmap_zero_page_area(m, base & PAGE_MASK, n); 4411 base += n; 4412 size -= n; 4413 n = PAGE_SIZE; 4414 } 4415 } 4416 } 4417 4418 /* 4419 * vm_hold_load_pages and vm_hold_free_pages get pages into 4420 * a buffers address space. The pages are anonymous and are 4421 * not associated with a file object. 4422 */ 4423 static void 4424 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4425 { 4426 vm_offset_t pg; 4427 vm_page_t p; 4428 int index; 4429 4430 BUF_CHECK_MAPPED(bp); 4431 4432 to = round_page(to); 4433 from = round_page(from); 4434 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4435 4436 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 4437 tryagain: 4438 /* 4439 * note: must allocate system pages since blocking here 4440 * could interfere with paging I/O, no matter which 4441 * process we are. 4442 */ 4443 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ | 4444 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT)); 4445 if (p == NULL) { 4446 VM_WAIT; 4447 goto tryagain; 4448 } 4449 pmap_qenter(pg, &p, 1); 4450 bp->b_pages[index] = p; 4451 } 4452 bp->b_npages = index; 4453 } 4454 4455 /* Return pages associated with this buf to the vm system */ 4456 static void 4457 vm_hold_free_pages(struct buf *bp, int newbsize) 4458 { 4459 vm_offset_t from; 4460 vm_page_t p; 4461 int index, newnpages; 4462 4463 BUF_CHECK_MAPPED(bp); 4464 4465 from = round_page((vm_offset_t)bp->b_data + newbsize); 4466 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4467 if (bp->b_npages > newnpages) 4468 pmap_qremove(from, bp->b_npages - newnpages); 4469 for (index = newnpages; index < bp->b_npages; index++) { 4470 p = bp->b_pages[index]; 4471 bp->b_pages[index] = NULL; 4472 if (vm_page_sbusied(p)) 4473 printf("vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 4474 (intmax_t)bp->b_blkno, (intmax_t)bp->b_lblkno); 4475 p->wire_count--; 4476 vm_page_free(p); 4477 atomic_subtract_int(&vm_cnt.v_wire_count, 1); 4478 } 4479 bp->b_npages = newnpages; 4480 } 4481 4482 /* 4483 * Map an IO request into kernel virtual address space. 4484 * 4485 * All requests are (re)mapped into kernel VA space. 4486 * Notice that we use b_bufsize for the size of the buffer 4487 * to be mapped. b_bcount might be modified by the driver. 4488 * 4489 * Note that even if the caller determines that the address space should 4490 * be valid, a race or a smaller-file mapped into a larger space may 4491 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 4492 * check the return value. 4493 * 4494 * This function only works with pager buffers. 4495 */ 4496 int 4497 vmapbuf(struct buf *bp, int mapbuf) 4498 { 4499 vm_prot_t prot; 4500 int pidx; 4501 4502 if (bp->b_bufsize < 0) 4503 return (-1); 4504 prot = VM_PROT_READ; 4505 if (bp->b_iocmd == BIO_READ) 4506 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 4507 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 4508 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages, 4509 btoc(MAXPHYS))) < 0) 4510 return (-1); 4511 bp->b_npages = pidx; 4512 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK; 4513 if (mapbuf || !unmapped_buf_allowed) { 4514 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_pages, pidx); 4515 bp->b_data = bp->b_kvabase + bp->b_offset; 4516 } else 4517 bp->b_data = unmapped_buf; 4518 return(0); 4519 } 4520 4521 /* 4522 * Free the io map PTEs associated with this IO operation. 4523 * We also invalidate the TLB entries and restore the original b_addr. 4524 * 4525 * This function only works with pager buffers. 4526 */ 4527 void 4528 vunmapbuf(struct buf *bp) 4529 { 4530 int npages; 4531 4532 npages = bp->b_npages; 4533 if (buf_mapped(bp)) 4534 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 4535 vm_page_unhold_pages(bp->b_pages, npages); 4536 4537 bp->b_data = unmapped_buf; 4538 } 4539 4540 void 4541 bdone(struct buf *bp) 4542 { 4543 struct mtx *mtxp; 4544 4545 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4546 mtx_lock(mtxp); 4547 bp->b_flags |= B_DONE; 4548 wakeup(bp); 4549 mtx_unlock(mtxp); 4550 } 4551 4552 void 4553 bwait(struct buf *bp, u_char pri, const char *wchan) 4554 { 4555 struct mtx *mtxp; 4556 4557 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4558 mtx_lock(mtxp); 4559 while ((bp->b_flags & B_DONE) == 0) 4560 msleep(bp, mtxp, pri, wchan, 0); 4561 mtx_unlock(mtxp); 4562 } 4563 4564 int 4565 bufsync(struct bufobj *bo, int waitfor) 4566 { 4567 4568 return (VOP_FSYNC(bo->__bo_vnode, waitfor, curthread)); 4569 } 4570 4571 void 4572 bufstrategy(struct bufobj *bo, struct buf *bp) 4573 { 4574 int i = 0; 4575 struct vnode *vp; 4576 4577 vp = bp->b_vp; 4578 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 4579 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 4580 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 4581 i = VOP_STRATEGY(vp, bp); 4582 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 4583 } 4584 4585 void 4586 bufobj_wrefl(struct bufobj *bo) 4587 { 4588 4589 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4590 ASSERT_BO_WLOCKED(bo); 4591 bo->bo_numoutput++; 4592 } 4593 4594 void 4595 bufobj_wref(struct bufobj *bo) 4596 { 4597 4598 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4599 BO_LOCK(bo); 4600 bo->bo_numoutput++; 4601 BO_UNLOCK(bo); 4602 } 4603 4604 void 4605 bufobj_wdrop(struct bufobj *bo) 4606 { 4607 4608 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 4609 BO_LOCK(bo); 4610 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 4611 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 4612 bo->bo_flag &= ~BO_WWAIT; 4613 wakeup(&bo->bo_numoutput); 4614 } 4615 BO_UNLOCK(bo); 4616 } 4617 4618 int 4619 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 4620 { 4621 int error; 4622 4623 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 4624 ASSERT_BO_WLOCKED(bo); 4625 error = 0; 4626 while (bo->bo_numoutput) { 4627 bo->bo_flag |= BO_WWAIT; 4628 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo), 4629 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 4630 if (error) 4631 break; 4632 } 4633 return (error); 4634 } 4635 4636 void 4637 bpin(struct buf *bp) 4638 { 4639 struct mtx *mtxp; 4640 4641 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4642 mtx_lock(mtxp); 4643 bp->b_pin_count++; 4644 mtx_unlock(mtxp); 4645 } 4646 4647 void 4648 bunpin(struct buf *bp) 4649 { 4650 struct mtx *mtxp; 4651 4652 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4653 mtx_lock(mtxp); 4654 if (--bp->b_pin_count == 0) 4655 wakeup(bp); 4656 mtx_unlock(mtxp); 4657 } 4658 4659 void 4660 bunpin_wait(struct buf *bp) 4661 { 4662 struct mtx *mtxp; 4663 4664 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4665 mtx_lock(mtxp); 4666 while (bp->b_pin_count > 0) 4667 msleep(bp, mtxp, PRIBIO, "bwunpin", 0); 4668 mtx_unlock(mtxp); 4669 } 4670 4671 /* 4672 * Set bio_data or bio_ma for struct bio from the struct buf. 4673 */ 4674 void 4675 bdata2bio(struct buf *bp, struct bio *bip) 4676 { 4677 4678 if (!buf_mapped(bp)) { 4679 KASSERT(unmapped_buf_allowed, ("unmapped")); 4680 bip->bio_ma = bp->b_pages; 4681 bip->bio_ma_n = bp->b_npages; 4682 bip->bio_data = unmapped_buf; 4683 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 4684 bip->bio_flags |= BIO_UNMAPPED; 4685 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) / 4686 PAGE_SIZE == bp->b_npages, 4687 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset, 4688 (long long)bip->bio_length, bip->bio_ma_n)); 4689 } else { 4690 bip->bio_data = bp->b_data; 4691 bip->bio_ma = NULL; 4692 } 4693 } 4694 4695 #include "opt_ddb.h" 4696 #ifdef DDB 4697 #include <ddb/ddb.h> 4698 4699 /* DDB command to show buffer data */ 4700 DB_SHOW_COMMAND(buffer, db_show_buffer) 4701 { 4702 /* get args */ 4703 struct buf *bp = (struct buf *)addr; 4704 4705 if (!have_addr) { 4706 db_printf("usage: show buffer <addr>\n"); 4707 return; 4708 } 4709 4710 db_printf("buf at %p\n", bp); 4711 db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n", 4712 (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags, 4713 PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS); 4714 db_printf( 4715 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 4716 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, " 4717 "b_dep = %p\n", 4718 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 4719 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 4720 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first); 4721 db_printf("b_kvabase = %p, b_kvasize = %d\n", 4722 bp->b_kvabase, bp->b_kvasize); 4723 if (bp->b_npages) { 4724 int i; 4725 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 4726 for (i = 0; i < bp->b_npages; i++) { 4727 vm_page_t m; 4728 m = bp->b_pages[i]; 4729 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 4730 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 4731 if ((i + 1) < bp->b_npages) 4732 db_printf(","); 4733 } 4734 db_printf("\n"); 4735 } 4736 db_printf(" "); 4737 BUF_LOCKPRINTINFO(bp); 4738 } 4739 4740 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 4741 { 4742 struct buf *bp; 4743 int i; 4744 4745 for (i = 0; i < nbuf; i++) { 4746 bp = &buf[i]; 4747 if (BUF_ISLOCKED(bp)) { 4748 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4749 db_printf("\n"); 4750 } 4751 } 4752 } 4753 4754 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 4755 { 4756 struct vnode *vp; 4757 struct buf *bp; 4758 4759 if (!have_addr) { 4760 db_printf("usage: show vnodebufs <addr>\n"); 4761 return; 4762 } 4763 vp = (struct vnode *)addr; 4764 db_printf("Clean buffers:\n"); 4765 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 4766 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4767 db_printf("\n"); 4768 } 4769 db_printf("Dirty buffers:\n"); 4770 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 4771 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4772 db_printf("\n"); 4773 } 4774 } 4775 4776 DB_COMMAND(countfreebufs, db_coundfreebufs) 4777 { 4778 struct buf *bp; 4779 int i, used = 0, nfree = 0; 4780 4781 if (have_addr) { 4782 db_printf("usage: countfreebufs\n"); 4783 return; 4784 } 4785 4786 for (i = 0; i < nbuf; i++) { 4787 bp = &buf[i]; 4788 if (bp->b_qindex == QUEUE_EMPTY) 4789 nfree++; 4790 else 4791 used++; 4792 } 4793 4794 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 4795 nfree + used); 4796 db_printf("numfreebuffers is %d\n", numfreebuffers); 4797 } 4798 #endif /* DDB */ 4799