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 acquisition"); 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 * Artificially 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 occurring 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) == 0 && BUF_ISLOCKED(bp)) || 1166 ((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI)) 1167 return (1); 1168 return (0); 1169 } 1170 1171 /* 1172 * Shutdown the system cleanly to prepare for reboot, halt, or power off. 1173 */ 1174 void 1175 bufshutdown(int show_busybufs) 1176 { 1177 static int first_buf_printf = 1; 1178 struct buf *bp; 1179 int iter, nbusy, pbusy; 1180 #ifndef PREEMPTION 1181 int subiter; 1182 #endif 1183 1184 /* 1185 * Sync filesystems for shutdown 1186 */ 1187 wdog_kern_pat(WD_LASTVAL); 1188 sys_sync(curthread, NULL); 1189 1190 /* 1191 * With soft updates, some buffers that are 1192 * written will be remarked as dirty until other 1193 * buffers are written. 1194 */ 1195 for (iter = pbusy = 0; iter < 20; iter++) { 1196 nbusy = 0; 1197 for (bp = &buf[nbuf]; --bp >= buf; ) 1198 if (isbufbusy(bp)) 1199 nbusy++; 1200 if (nbusy == 0) { 1201 if (first_buf_printf) 1202 printf("All buffers synced."); 1203 break; 1204 } 1205 if (first_buf_printf) { 1206 printf("Syncing disks, buffers remaining... "); 1207 first_buf_printf = 0; 1208 } 1209 printf("%d ", nbusy); 1210 if (nbusy < pbusy) 1211 iter = 0; 1212 pbusy = nbusy; 1213 1214 wdog_kern_pat(WD_LASTVAL); 1215 sys_sync(curthread, NULL); 1216 1217 #ifdef PREEMPTION 1218 /* 1219 * Drop Giant and spin for a while to allow 1220 * interrupt threads to run. 1221 */ 1222 DROP_GIANT(); 1223 DELAY(50000 * iter); 1224 PICKUP_GIANT(); 1225 #else 1226 /* 1227 * Drop Giant and context switch several times to 1228 * allow interrupt threads to run. 1229 */ 1230 DROP_GIANT(); 1231 for (subiter = 0; subiter < 50 * iter; subiter++) { 1232 thread_lock(curthread); 1233 mi_switch(SW_VOL, NULL); 1234 thread_unlock(curthread); 1235 DELAY(1000); 1236 } 1237 PICKUP_GIANT(); 1238 #endif 1239 } 1240 printf("\n"); 1241 /* 1242 * Count only busy local buffers to prevent forcing 1243 * a fsck if we're just a client of a wedged NFS server 1244 */ 1245 nbusy = 0; 1246 for (bp = &buf[nbuf]; --bp >= buf; ) { 1247 if (isbufbusy(bp)) { 1248 #if 0 1249 /* XXX: This is bogus. We should probably have a BO_REMOTE flag instead */ 1250 if (bp->b_dev == NULL) { 1251 TAILQ_REMOVE(&mountlist, 1252 bp->b_vp->v_mount, mnt_list); 1253 continue; 1254 } 1255 #endif 1256 nbusy++; 1257 if (show_busybufs > 0) { 1258 printf( 1259 "%d: buf:%p, vnode:%p, flags:%0x, blkno:%jd, lblkno:%jd, buflock:", 1260 nbusy, bp, bp->b_vp, bp->b_flags, 1261 (intmax_t)bp->b_blkno, 1262 (intmax_t)bp->b_lblkno); 1263 BUF_LOCKPRINTINFO(bp); 1264 if (show_busybufs > 1) 1265 vn_printf(bp->b_vp, 1266 "vnode content: "); 1267 } 1268 } 1269 } 1270 if (nbusy) { 1271 /* 1272 * Failed to sync all blocks. Indicate this and don't 1273 * unmount filesystems (thus forcing an fsck on reboot). 1274 */ 1275 printf("Giving up on %d buffers\n", nbusy); 1276 DELAY(5000000); /* 5 seconds */ 1277 } else { 1278 if (!first_buf_printf) 1279 printf("Final sync complete\n"); 1280 /* 1281 * Unmount filesystems 1282 */ 1283 if (panicstr == NULL) 1284 vfs_unmountall(); 1285 } 1286 swapoff_all(); 1287 DELAY(100000); /* wait for console output to finish */ 1288 } 1289 1290 static void 1291 bpmap_qenter(struct buf *bp) 1292 { 1293 1294 BUF_CHECK_MAPPED(bp); 1295 1296 /* 1297 * bp->b_data is relative to bp->b_offset, but 1298 * bp->b_offset may be offset into the first page. 1299 */ 1300 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data); 1301 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages); 1302 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 1303 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 1304 } 1305 1306 /* 1307 * binsfree: 1308 * 1309 * Insert the buffer into the appropriate free list. 1310 */ 1311 static void 1312 binsfree(struct buf *bp, int qindex) 1313 { 1314 struct mtx *olock, *nlock; 1315 1316 if (qindex != QUEUE_EMPTY) { 1317 BUF_ASSERT_XLOCKED(bp); 1318 } 1319 1320 /* 1321 * Stick to the same clean queue for the lifetime of the buf to 1322 * limit locking below. Otherwise pick ont sequentially. 1323 */ 1324 if (qindex == QUEUE_CLEAN) { 1325 if (bqisclean(bp->b_qindex)) 1326 qindex = bp->b_qindex; 1327 else 1328 qindex = bqcleanq(); 1329 } 1330 1331 /* 1332 * Handle delayed bremfree() processing. 1333 */ 1334 nlock = bqlock(qindex); 1335 if (bp->b_flags & B_REMFREE) { 1336 olock = bqlock(bp->b_qindex); 1337 mtx_lock(olock); 1338 bremfreel(bp); 1339 if (olock != nlock) { 1340 mtx_unlock(olock); 1341 mtx_lock(nlock); 1342 } 1343 } else 1344 mtx_lock(nlock); 1345 1346 if (bp->b_qindex != QUEUE_NONE) 1347 panic("binsfree: free buffer onto another queue???"); 1348 1349 bp->b_qindex = qindex; 1350 if (bp->b_flags & B_AGE) 1351 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1352 else 1353 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1354 #ifdef INVARIANTS 1355 bq_len[bp->b_qindex]++; 1356 #endif 1357 mtx_unlock(nlock); 1358 } 1359 1360 /* 1361 * buf_free: 1362 * 1363 * Free a buffer to the buf zone once it no longer has valid contents. 1364 */ 1365 static void 1366 buf_free(struct buf *bp) 1367 { 1368 1369 if (bp->b_flags & B_REMFREE) 1370 bremfreef(bp); 1371 if (bp->b_vflags & BV_BKGRDINPROG) 1372 panic("losing buffer 1"); 1373 if (bp->b_rcred != NOCRED) { 1374 crfree(bp->b_rcred); 1375 bp->b_rcred = NOCRED; 1376 } 1377 if (bp->b_wcred != NOCRED) { 1378 crfree(bp->b_wcred); 1379 bp->b_wcred = NOCRED; 1380 } 1381 if (!LIST_EMPTY(&bp->b_dep)) 1382 buf_deallocate(bp); 1383 bufkva_free(bp); 1384 BUF_UNLOCK(bp); 1385 uma_zfree(buf_zone, bp); 1386 atomic_add_int(&numfreebuffers, 1); 1387 bufspace_wakeup(); 1388 } 1389 1390 /* 1391 * buf_import: 1392 * 1393 * Import bufs into the uma cache from the buf list. The system still 1394 * expects a static array of bufs and much of the synchronization 1395 * around bufs assumes type stable storage. As a result, UMA is used 1396 * only as a per-cpu cache of bufs still maintained on a global list. 1397 */ 1398 static int 1399 buf_import(void *arg, void **store, int cnt, int flags) 1400 { 1401 struct buf *bp; 1402 int i; 1403 1404 mtx_lock(&bqlocks[QUEUE_EMPTY]); 1405 for (i = 0; i < cnt; i++) { 1406 bp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1407 if (bp == NULL) 1408 break; 1409 bremfreel(bp); 1410 store[i] = bp; 1411 } 1412 mtx_unlock(&bqlocks[QUEUE_EMPTY]); 1413 1414 return (i); 1415 } 1416 1417 /* 1418 * buf_release: 1419 * 1420 * Release bufs from the uma cache back to the buffer queues. 1421 */ 1422 static void 1423 buf_release(void *arg, void **store, int cnt) 1424 { 1425 int i; 1426 1427 for (i = 0; i < cnt; i++) 1428 binsfree(store[i], QUEUE_EMPTY); 1429 } 1430 1431 /* 1432 * buf_alloc: 1433 * 1434 * Allocate an empty buffer header. 1435 */ 1436 static struct buf * 1437 buf_alloc(void) 1438 { 1439 struct buf *bp; 1440 1441 bp = uma_zalloc(buf_zone, M_NOWAIT); 1442 if (bp == NULL) { 1443 bufspace_daemonwakeup(); 1444 atomic_add_int(&numbufallocfails, 1); 1445 return (NULL); 1446 } 1447 1448 /* 1449 * Wake-up the bufspace daemon on transition. 1450 */ 1451 if (atomic_fetchadd_int(&numfreebuffers, -1) == lofreebuffers) 1452 bufspace_daemonwakeup(); 1453 1454 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1455 panic("getnewbuf_empty: Locked buf %p on free queue.", bp); 1456 1457 KASSERT(bp->b_vp == NULL, 1458 ("bp: %p still has vnode %p.", bp, bp->b_vp)); 1459 KASSERT((bp->b_flags & (B_DELWRI | B_NOREUSE)) == 0, 1460 ("invalid buffer %p flags %#x", bp, bp->b_flags)); 1461 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 1462 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags)); 1463 KASSERT(bp->b_npages == 0, 1464 ("bp: %p still has %d vm pages\n", bp, bp->b_npages)); 1465 KASSERT(bp->b_kvasize == 0, ("bp: %p still has kva\n", bp)); 1466 KASSERT(bp->b_bufsize == 0, ("bp: %p still has bufspace\n", bp)); 1467 1468 bp->b_flags = 0; 1469 bp->b_ioflags = 0; 1470 bp->b_xflags = 0; 1471 bp->b_vflags = 0; 1472 bp->b_vp = NULL; 1473 bp->b_blkno = bp->b_lblkno = 0; 1474 bp->b_offset = NOOFFSET; 1475 bp->b_iodone = 0; 1476 bp->b_error = 0; 1477 bp->b_resid = 0; 1478 bp->b_bcount = 0; 1479 bp->b_npages = 0; 1480 bp->b_dirtyoff = bp->b_dirtyend = 0; 1481 bp->b_bufobj = NULL; 1482 bp->b_data = bp->b_kvabase = unmapped_buf; 1483 bp->b_fsprivate1 = NULL; 1484 bp->b_fsprivate2 = NULL; 1485 bp->b_fsprivate3 = NULL; 1486 LIST_INIT(&bp->b_dep); 1487 1488 return (bp); 1489 } 1490 1491 /* 1492 * buf_qrecycle: 1493 * 1494 * Free a buffer from the given bufqueue. kva controls whether the 1495 * freed buf must own some kva resources. This is used for 1496 * defragmenting. 1497 */ 1498 static int 1499 buf_qrecycle(int qindex, bool kva) 1500 { 1501 struct buf *bp, *nbp; 1502 1503 if (kva) 1504 atomic_add_int(&bufdefragcnt, 1); 1505 nbp = NULL; 1506 mtx_lock(&bqlocks[qindex]); 1507 nbp = TAILQ_FIRST(&bufqueues[qindex]); 1508 1509 /* 1510 * Run scan, possibly freeing data and/or kva mappings on the fly 1511 * depending. 1512 */ 1513 while ((bp = nbp) != NULL) { 1514 /* 1515 * Calculate next bp (we can only use it if we do not 1516 * release the bqlock). 1517 */ 1518 nbp = TAILQ_NEXT(bp, b_freelist); 1519 1520 /* 1521 * If we are defragging then we need a buffer with 1522 * some kva to reclaim. 1523 */ 1524 if (kva && bp->b_kvasize == 0) 1525 continue; 1526 1527 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1528 continue; 1529 1530 /* 1531 * Skip buffers with background writes in progress. 1532 */ 1533 if ((bp->b_vflags & BV_BKGRDINPROG) != 0) { 1534 BUF_UNLOCK(bp); 1535 continue; 1536 } 1537 1538 KASSERT(bp->b_qindex == qindex, 1539 ("getnewbuf: inconsistent queue %d bp %p", qindex, bp)); 1540 /* 1541 * NOTE: nbp is now entirely invalid. We can only restart 1542 * the scan from this point on. 1543 */ 1544 bremfreel(bp); 1545 mtx_unlock(&bqlocks[qindex]); 1546 1547 /* 1548 * Requeue the background write buffer with error and 1549 * restart the scan. 1550 */ 1551 if ((bp->b_vflags & BV_BKGRDERR) != 0) { 1552 bqrelse(bp); 1553 mtx_lock(&bqlocks[qindex]); 1554 nbp = TAILQ_FIRST(&bufqueues[qindex]); 1555 continue; 1556 } 1557 bp->b_flags |= B_INVAL; 1558 brelse(bp); 1559 return (0); 1560 } 1561 mtx_unlock(&bqlocks[qindex]); 1562 1563 return (ENOBUFS); 1564 } 1565 1566 /* 1567 * buf_recycle: 1568 * 1569 * Iterate through all clean queues until we find a buf to recycle or 1570 * exhaust the search. 1571 */ 1572 static int 1573 buf_recycle(bool kva) 1574 { 1575 int qindex, first_qindex; 1576 1577 qindex = first_qindex = bqcleanq(); 1578 do { 1579 if (buf_qrecycle(qindex, kva) == 0) 1580 return (0); 1581 if (++qindex == QUEUE_CLEAN + clean_queues) 1582 qindex = QUEUE_CLEAN; 1583 } while (qindex != first_qindex); 1584 1585 return (ENOBUFS); 1586 } 1587 1588 /* 1589 * buf_scan: 1590 * 1591 * Scan the clean queues looking for a buffer to recycle. needsbuffer 1592 * is set on failure so that the caller may optionally bufspace_wait() 1593 * in a race-free fashion. 1594 */ 1595 static int 1596 buf_scan(bool defrag) 1597 { 1598 int error; 1599 1600 /* 1601 * To avoid heavy synchronization and wakeup races we set 1602 * needsbuffer and re-poll before failing. This ensures that 1603 * no frees can be missed between an unsuccessful poll and 1604 * going to sleep in a synchronized fashion. 1605 */ 1606 if ((error = buf_recycle(defrag)) != 0) { 1607 atomic_set_int(&needsbuffer, 1); 1608 bufspace_daemonwakeup(); 1609 error = buf_recycle(defrag); 1610 } 1611 if (error == 0) 1612 atomic_add_int(&getnewbufrestarts, 1); 1613 return (error); 1614 } 1615 1616 /* 1617 * bremfree: 1618 * 1619 * Mark the buffer for removal from the appropriate free list. 1620 * 1621 */ 1622 void 1623 bremfree(struct buf *bp) 1624 { 1625 1626 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1627 KASSERT((bp->b_flags & B_REMFREE) == 0, 1628 ("bremfree: buffer %p already marked for delayed removal.", bp)); 1629 KASSERT(bp->b_qindex != QUEUE_NONE, 1630 ("bremfree: buffer %p not on a queue.", bp)); 1631 BUF_ASSERT_XLOCKED(bp); 1632 1633 bp->b_flags |= B_REMFREE; 1634 } 1635 1636 /* 1637 * bremfreef: 1638 * 1639 * Force an immediate removal from a free list. Used only in nfs when 1640 * it abuses the b_freelist pointer. 1641 */ 1642 void 1643 bremfreef(struct buf *bp) 1644 { 1645 struct mtx *qlock; 1646 1647 qlock = bqlock(bp->b_qindex); 1648 mtx_lock(qlock); 1649 bremfreel(bp); 1650 mtx_unlock(qlock); 1651 } 1652 1653 /* 1654 * bremfreel: 1655 * 1656 * Removes a buffer from the free list, must be called with the 1657 * correct qlock held. 1658 */ 1659 static void 1660 bremfreel(struct buf *bp) 1661 { 1662 1663 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X", 1664 bp, bp->b_vp, bp->b_flags); 1665 KASSERT(bp->b_qindex != QUEUE_NONE, 1666 ("bremfreel: buffer %p not on a queue.", bp)); 1667 if (bp->b_qindex != QUEUE_EMPTY) { 1668 BUF_ASSERT_XLOCKED(bp); 1669 } 1670 mtx_assert(bqlock(bp->b_qindex), MA_OWNED); 1671 1672 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 1673 #ifdef INVARIANTS 1674 KASSERT(bq_len[bp->b_qindex] >= 1, ("queue %d underflow", 1675 bp->b_qindex)); 1676 bq_len[bp->b_qindex]--; 1677 #endif 1678 bp->b_qindex = QUEUE_NONE; 1679 bp->b_flags &= ~B_REMFREE; 1680 } 1681 1682 /* 1683 * bufkva_free: 1684 * 1685 * Free the kva allocation for a buffer. 1686 * 1687 */ 1688 static void 1689 bufkva_free(struct buf *bp) 1690 { 1691 1692 #ifdef INVARIANTS 1693 if (bp->b_kvasize == 0) { 1694 KASSERT(bp->b_kvabase == unmapped_buf && 1695 bp->b_data == unmapped_buf, 1696 ("Leaked KVA space on %p", bp)); 1697 } else if (buf_mapped(bp)) 1698 BUF_CHECK_MAPPED(bp); 1699 else 1700 BUF_CHECK_UNMAPPED(bp); 1701 #endif 1702 if (bp->b_kvasize == 0) 1703 return; 1704 1705 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, bp->b_kvasize); 1706 atomic_subtract_long(&bufkvaspace, bp->b_kvasize); 1707 atomic_add_int(&buffreekvacnt, 1); 1708 bp->b_data = bp->b_kvabase = unmapped_buf; 1709 bp->b_kvasize = 0; 1710 } 1711 1712 /* 1713 * bufkva_alloc: 1714 * 1715 * Allocate the buffer KVA and set b_kvasize and b_kvabase. 1716 */ 1717 static int 1718 bufkva_alloc(struct buf *bp, int maxsize, int gbflags) 1719 { 1720 vm_offset_t addr; 1721 int error; 1722 1723 KASSERT((gbflags & GB_UNMAPPED) == 0 || (gbflags & GB_KVAALLOC) != 0, 1724 ("Invalid gbflags 0x%x in %s", gbflags, __func__)); 1725 1726 bufkva_free(bp); 1727 1728 addr = 0; 1729 error = vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr); 1730 if (error != 0) { 1731 /* 1732 * Buffer map is too fragmented. Request the caller 1733 * to defragment the map. 1734 */ 1735 return (error); 1736 } 1737 bp->b_kvabase = (caddr_t)addr; 1738 bp->b_kvasize = maxsize; 1739 atomic_add_long(&bufkvaspace, bp->b_kvasize); 1740 if ((gbflags & GB_UNMAPPED) != 0) { 1741 bp->b_data = unmapped_buf; 1742 BUF_CHECK_UNMAPPED(bp); 1743 } else { 1744 bp->b_data = bp->b_kvabase; 1745 BUF_CHECK_MAPPED(bp); 1746 } 1747 return (0); 1748 } 1749 1750 /* 1751 * bufkva_reclaim: 1752 * 1753 * Reclaim buffer kva by freeing buffers holding kva. This is a vmem 1754 * callback that fires to avoid returning failure. 1755 */ 1756 static void 1757 bufkva_reclaim(vmem_t *vmem, int flags) 1758 { 1759 int i; 1760 1761 for (i = 0; i < 5; i++) 1762 if (buf_scan(true) != 0) 1763 break; 1764 return; 1765 } 1766 1767 1768 /* 1769 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 1770 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 1771 * the buffer is valid and we do not have to do anything. 1772 */ 1773 void 1774 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, 1775 int cnt, struct ucred * cred) 1776 { 1777 struct buf *rabp; 1778 int i; 1779 1780 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 1781 if (inmem(vp, *rablkno)) 1782 continue; 1783 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 1784 1785 if ((rabp->b_flags & B_CACHE) == 0) { 1786 if (!TD_IS_IDLETHREAD(curthread)) { 1787 #ifdef RACCT 1788 if (racct_enable) { 1789 PROC_LOCK(curproc); 1790 racct_add_buf(curproc, rabp, 0); 1791 PROC_UNLOCK(curproc); 1792 } 1793 #endif /* RACCT */ 1794 curthread->td_ru.ru_inblock++; 1795 } 1796 rabp->b_flags |= B_ASYNC; 1797 rabp->b_flags &= ~B_INVAL; 1798 rabp->b_ioflags &= ~BIO_ERROR; 1799 rabp->b_iocmd = BIO_READ; 1800 if (rabp->b_rcred == NOCRED && cred != NOCRED) 1801 rabp->b_rcred = crhold(cred); 1802 vfs_busy_pages(rabp, 0); 1803 BUF_KERNPROC(rabp); 1804 rabp->b_iooffset = dbtob(rabp->b_blkno); 1805 bstrategy(rabp); 1806 } else { 1807 brelse(rabp); 1808 } 1809 } 1810 } 1811 1812 /* 1813 * Entry point for bread() and breadn() via #defines in sys/buf.h. 1814 * 1815 * Get a buffer with the specified data. Look in the cache first. We 1816 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 1817 * is set, the buffer is valid and we do not have to do anything, see 1818 * getblk(). Also starts asynchronous I/O on read-ahead blocks. 1819 * 1820 * Always return a NULL buffer pointer (in bpp) when returning an error. 1821 */ 1822 int 1823 breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno, 1824 int *rabsize, int cnt, struct ucred *cred, int flags, struct buf **bpp) 1825 { 1826 struct buf *bp; 1827 int rv = 0, readwait = 0; 1828 1829 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 1830 /* 1831 * Can only return NULL if GB_LOCK_NOWAIT flag is specified. 1832 */ 1833 *bpp = bp = getblk(vp, blkno, size, 0, 0, flags); 1834 if (bp == NULL) 1835 return (EBUSY); 1836 1837 /* if not found in cache, do some I/O */ 1838 if ((bp->b_flags & B_CACHE) == 0) { 1839 if (!TD_IS_IDLETHREAD(curthread)) { 1840 #ifdef RACCT 1841 if (racct_enable) { 1842 PROC_LOCK(curproc); 1843 racct_add_buf(curproc, bp, 0); 1844 PROC_UNLOCK(curproc); 1845 } 1846 #endif /* RACCT */ 1847 curthread->td_ru.ru_inblock++; 1848 } 1849 bp->b_iocmd = BIO_READ; 1850 bp->b_flags &= ~B_INVAL; 1851 bp->b_ioflags &= ~BIO_ERROR; 1852 if (bp->b_rcred == NOCRED && cred != NOCRED) 1853 bp->b_rcred = crhold(cred); 1854 vfs_busy_pages(bp, 0); 1855 bp->b_iooffset = dbtob(bp->b_blkno); 1856 bstrategy(bp); 1857 ++readwait; 1858 } 1859 1860 breada(vp, rablkno, rabsize, cnt, cred); 1861 1862 if (readwait) { 1863 rv = bufwait(bp); 1864 if (rv != 0) { 1865 brelse(bp); 1866 *bpp = NULL; 1867 } 1868 } 1869 return (rv); 1870 } 1871 1872 /* 1873 * Write, release buffer on completion. (Done by iodone 1874 * if async). Do not bother writing anything if the buffer 1875 * is invalid. 1876 * 1877 * Note that we set B_CACHE here, indicating that buffer is 1878 * fully valid and thus cacheable. This is true even of NFS 1879 * now so we set it generally. This could be set either here 1880 * or in biodone() since the I/O is synchronous. We put it 1881 * here. 1882 */ 1883 int 1884 bufwrite(struct buf *bp) 1885 { 1886 int oldflags; 1887 struct vnode *vp; 1888 long space; 1889 int vp_md; 1890 1891 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1892 if ((bp->b_bufobj->bo_flag & BO_DEAD) != 0) { 1893 bp->b_flags |= B_INVAL | B_RELBUF; 1894 bp->b_flags &= ~B_CACHE; 1895 brelse(bp); 1896 return (ENXIO); 1897 } 1898 if (bp->b_flags & B_INVAL) { 1899 brelse(bp); 1900 return (0); 1901 } 1902 1903 if (bp->b_flags & B_BARRIER) 1904 barrierwrites++; 1905 1906 oldflags = bp->b_flags; 1907 1908 BUF_ASSERT_HELD(bp); 1909 1910 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 1911 ("FFS background buffer should not get here %p", bp)); 1912 1913 vp = bp->b_vp; 1914 if (vp) 1915 vp_md = vp->v_vflag & VV_MD; 1916 else 1917 vp_md = 0; 1918 1919 /* 1920 * Mark the buffer clean. Increment the bufobj write count 1921 * before bundirty() call, to prevent other thread from seeing 1922 * empty dirty list and zero counter for writes in progress, 1923 * falsely indicating that the bufobj is clean. 1924 */ 1925 bufobj_wref(bp->b_bufobj); 1926 bundirty(bp); 1927 1928 bp->b_flags &= ~B_DONE; 1929 bp->b_ioflags &= ~BIO_ERROR; 1930 bp->b_flags |= B_CACHE; 1931 bp->b_iocmd = BIO_WRITE; 1932 1933 vfs_busy_pages(bp, 1); 1934 1935 /* 1936 * Normal bwrites pipeline writes 1937 */ 1938 bp->b_runningbufspace = bp->b_bufsize; 1939 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace); 1940 1941 if (!TD_IS_IDLETHREAD(curthread)) { 1942 #ifdef RACCT 1943 if (racct_enable) { 1944 PROC_LOCK(curproc); 1945 racct_add_buf(curproc, bp, 1); 1946 PROC_UNLOCK(curproc); 1947 } 1948 #endif /* RACCT */ 1949 curthread->td_ru.ru_oublock++; 1950 } 1951 if (oldflags & B_ASYNC) 1952 BUF_KERNPROC(bp); 1953 bp->b_iooffset = dbtob(bp->b_blkno); 1954 bstrategy(bp); 1955 1956 if ((oldflags & B_ASYNC) == 0) { 1957 int rtval = bufwait(bp); 1958 brelse(bp); 1959 return (rtval); 1960 } else if (space > hirunningspace) { 1961 /* 1962 * don't allow the async write to saturate the I/O 1963 * system. We will not deadlock here because 1964 * we are blocking waiting for I/O that is already in-progress 1965 * to complete. We do not block here if it is the update 1966 * or syncer daemon trying to clean up as that can lead 1967 * to deadlock. 1968 */ 1969 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 1970 waitrunningbufspace(); 1971 } 1972 1973 return (0); 1974 } 1975 1976 void 1977 bufbdflush(struct bufobj *bo, struct buf *bp) 1978 { 1979 struct buf *nbp; 1980 1981 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 1982 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 1983 altbufferflushes++; 1984 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 1985 BO_LOCK(bo); 1986 /* 1987 * Try to find a buffer to flush. 1988 */ 1989 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 1990 if ((nbp->b_vflags & BV_BKGRDINPROG) || 1991 BUF_LOCK(nbp, 1992 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 1993 continue; 1994 if (bp == nbp) 1995 panic("bdwrite: found ourselves"); 1996 BO_UNLOCK(bo); 1997 /* Don't countdeps with the bo lock held. */ 1998 if (buf_countdeps(nbp, 0)) { 1999 BO_LOCK(bo); 2000 BUF_UNLOCK(nbp); 2001 continue; 2002 } 2003 if (nbp->b_flags & B_CLUSTEROK) { 2004 vfs_bio_awrite(nbp); 2005 } else { 2006 bremfree(nbp); 2007 bawrite(nbp); 2008 } 2009 dirtybufferflushes++; 2010 break; 2011 } 2012 if (nbp == NULL) 2013 BO_UNLOCK(bo); 2014 } 2015 } 2016 2017 /* 2018 * Delayed write. (Buffer is marked dirty). Do not bother writing 2019 * anything if the buffer is marked invalid. 2020 * 2021 * Note that since the buffer must be completely valid, we can safely 2022 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 2023 * biodone() in order to prevent getblk from writing the buffer 2024 * out synchronously. 2025 */ 2026 void 2027 bdwrite(struct buf *bp) 2028 { 2029 struct thread *td = curthread; 2030 struct vnode *vp; 2031 struct bufobj *bo; 2032 2033 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2034 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2035 KASSERT((bp->b_flags & B_BARRIER) == 0, 2036 ("Barrier request in delayed write %p", bp)); 2037 BUF_ASSERT_HELD(bp); 2038 2039 if (bp->b_flags & B_INVAL) { 2040 brelse(bp); 2041 return; 2042 } 2043 2044 /* 2045 * If we have too many dirty buffers, don't create any more. 2046 * If we are wildly over our limit, then force a complete 2047 * cleanup. Otherwise, just keep the situation from getting 2048 * out of control. Note that we have to avoid a recursive 2049 * disaster and not try to clean up after our own cleanup! 2050 */ 2051 vp = bp->b_vp; 2052 bo = bp->b_bufobj; 2053 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 2054 td->td_pflags |= TDP_INBDFLUSH; 2055 BO_BDFLUSH(bo, bp); 2056 td->td_pflags &= ~TDP_INBDFLUSH; 2057 } else 2058 recursiveflushes++; 2059 2060 bdirty(bp); 2061 /* 2062 * Set B_CACHE, indicating that the buffer is fully valid. This is 2063 * true even of NFS now. 2064 */ 2065 bp->b_flags |= B_CACHE; 2066 2067 /* 2068 * This bmap keeps the system from needing to do the bmap later, 2069 * perhaps when the system is attempting to do a sync. Since it 2070 * is likely that the indirect block -- or whatever other datastructure 2071 * that the filesystem needs is still in memory now, it is a good 2072 * thing to do this. Note also, that if the pageout daemon is 2073 * requesting a sync -- there might not be enough memory to do 2074 * the bmap then... So, this is important to do. 2075 */ 2076 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 2077 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 2078 } 2079 2080 /* 2081 * Set the *dirty* buffer range based upon the VM system dirty 2082 * pages. 2083 * 2084 * Mark the buffer pages as clean. We need to do this here to 2085 * satisfy the vnode_pager and the pageout daemon, so that it 2086 * thinks that the pages have been "cleaned". Note that since 2087 * the pages are in a delayed write buffer -- the VFS layer 2088 * "will" see that the pages get written out on the next sync, 2089 * or perhaps the cluster will be completed. 2090 */ 2091 vfs_clean_pages_dirty_buf(bp); 2092 bqrelse(bp); 2093 2094 /* 2095 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 2096 * due to the softdep code. 2097 */ 2098 } 2099 2100 /* 2101 * bdirty: 2102 * 2103 * Turn buffer into delayed write request. We must clear BIO_READ and 2104 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 2105 * itself to properly update it in the dirty/clean lists. We mark it 2106 * B_DONE to ensure that any asynchronization of the buffer properly 2107 * clears B_DONE ( else a panic will occur later ). 2108 * 2109 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 2110 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 2111 * should only be called if the buffer is known-good. 2112 * 2113 * Since the buffer is not on a queue, we do not update the numfreebuffers 2114 * count. 2115 * 2116 * The buffer must be on QUEUE_NONE. 2117 */ 2118 void 2119 bdirty(struct buf *bp) 2120 { 2121 2122 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 2123 bp, bp->b_vp, bp->b_flags); 2124 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2125 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 2126 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 2127 BUF_ASSERT_HELD(bp); 2128 bp->b_flags &= ~(B_RELBUF); 2129 bp->b_iocmd = BIO_WRITE; 2130 2131 if ((bp->b_flags & B_DELWRI) == 0) { 2132 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 2133 reassignbuf(bp); 2134 bdirtyadd(); 2135 } 2136 } 2137 2138 /* 2139 * bundirty: 2140 * 2141 * Clear B_DELWRI for buffer. 2142 * 2143 * Since the buffer is not on a queue, we do not update the numfreebuffers 2144 * count. 2145 * 2146 * The buffer must be on QUEUE_NONE. 2147 */ 2148 2149 void 2150 bundirty(struct buf *bp) 2151 { 2152 2153 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2154 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2155 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 2156 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 2157 BUF_ASSERT_HELD(bp); 2158 2159 if (bp->b_flags & B_DELWRI) { 2160 bp->b_flags &= ~B_DELWRI; 2161 reassignbuf(bp); 2162 bdirtysub(); 2163 } 2164 /* 2165 * Since it is now being written, we can clear its deferred write flag. 2166 */ 2167 bp->b_flags &= ~B_DEFERRED; 2168 } 2169 2170 /* 2171 * bawrite: 2172 * 2173 * Asynchronous write. Start output on a buffer, but do not wait for 2174 * it to complete. The buffer is released when the output completes. 2175 * 2176 * bwrite() ( or the VOP routine anyway ) is responsible for handling 2177 * B_INVAL buffers. Not us. 2178 */ 2179 void 2180 bawrite(struct buf *bp) 2181 { 2182 2183 bp->b_flags |= B_ASYNC; 2184 (void) bwrite(bp); 2185 } 2186 2187 /* 2188 * babarrierwrite: 2189 * 2190 * Asynchronous barrier write. Start output on a buffer, but do not 2191 * wait for it to complete. Place a write barrier after this write so 2192 * that this buffer and all buffers written before it are committed to 2193 * the disk before any buffers written after this write are committed 2194 * to the disk. The buffer is released when the output completes. 2195 */ 2196 void 2197 babarrierwrite(struct buf *bp) 2198 { 2199 2200 bp->b_flags |= B_ASYNC | B_BARRIER; 2201 (void) bwrite(bp); 2202 } 2203 2204 /* 2205 * bbarrierwrite: 2206 * 2207 * Synchronous barrier write. Start output on a buffer and wait for 2208 * it to complete. Place a write barrier after this write so that 2209 * this buffer and all buffers written before it are committed to 2210 * the disk before any buffers written after this write are committed 2211 * to the disk. The buffer is released when the output completes. 2212 */ 2213 int 2214 bbarrierwrite(struct buf *bp) 2215 { 2216 2217 bp->b_flags |= B_BARRIER; 2218 return (bwrite(bp)); 2219 } 2220 2221 /* 2222 * bwillwrite: 2223 * 2224 * Called prior to the locking of any vnodes when we are expecting to 2225 * write. We do not want to starve the buffer cache with too many 2226 * dirty buffers so we block here. By blocking prior to the locking 2227 * of any vnodes we attempt to avoid the situation where a locked vnode 2228 * prevents the various system daemons from flushing related buffers. 2229 */ 2230 void 2231 bwillwrite(void) 2232 { 2233 2234 if (numdirtybuffers >= hidirtybuffers) { 2235 mtx_lock(&bdirtylock); 2236 while (numdirtybuffers >= hidirtybuffers) { 2237 bdirtywait = 1; 2238 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4), 2239 "flswai", 0); 2240 } 2241 mtx_unlock(&bdirtylock); 2242 } 2243 } 2244 2245 /* 2246 * Return true if we have too many dirty buffers. 2247 */ 2248 int 2249 buf_dirty_count_severe(void) 2250 { 2251 2252 return(numdirtybuffers >= hidirtybuffers); 2253 } 2254 2255 /* 2256 * brelse: 2257 * 2258 * Release a busy buffer and, if requested, free its resources. The 2259 * buffer will be stashed in the appropriate bufqueue[] allowing it 2260 * to be accessed later as a cache entity or reused for other purposes. 2261 */ 2262 void 2263 brelse(struct buf *bp) 2264 { 2265 int qindex; 2266 2267 /* 2268 * Many functions erroneously call brelse with a NULL bp under rare 2269 * error conditions. Simply return when called with a NULL bp. 2270 */ 2271 if (bp == NULL) 2272 return; 2273 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 2274 bp, bp->b_vp, bp->b_flags); 2275 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 2276 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 2277 KASSERT((bp->b_flags & B_VMIO) != 0 || (bp->b_flags & B_NOREUSE) == 0, 2278 ("brelse: non-VMIO buffer marked NOREUSE")); 2279 2280 if (BUF_LOCKRECURSED(bp)) { 2281 /* 2282 * Do not process, in particular, do not handle the 2283 * B_INVAL/B_RELBUF and do not release to free list. 2284 */ 2285 BUF_UNLOCK(bp); 2286 return; 2287 } 2288 2289 if (bp->b_flags & B_MANAGED) { 2290 bqrelse(bp); 2291 return; 2292 } 2293 2294 if ((bp->b_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) { 2295 BO_LOCK(bp->b_bufobj); 2296 bp->b_vflags &= ~BV_BKGRDERR; 2297 BO_UNLOCK(bp->b_bufobj); 2298 bdirty(bp); 2299 } 2300 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 2301 !(bp->b_flags & B_INVAL)) { 2302 /* 2303 * Failed write, redirty. Must clear BIO_ERROR to prevent 2304 * pages from being scrapped. 2305 */ 2306 bp->b_ioflags &= ~BIO_ERROR; 2307 bdirty(bp); 2308 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 2309 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 2310 /* 2311 * Either a failed read I/O or we were asked to free or not 2312 * cache the buffer. 2313 */ 2314 bp->b_flags |= B_INVAL; 2315 if (!LIST_EMPTY(&bp->b_dep)) 2316 buf_deallocate(bp); 2317 if (bp->b_flags & B_DELWRI) 2318 bdirtysub(); 2319 bp->b_flags &= ~(B_DELWRI | B_CACHE); 2320 if ((bp->b_flags & B_VMIO) == 0) { 2321 allocbuf(bp, 0); 2322 if (bp->b_vp) 2323 brelvp(bp); 2324 } 2325 } 2326 2327 /* 2328 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_truncate() 2329 * is called with B_DELWRI set, the underlying pages may wind up 2330 * getting freed causing a previous write (bdwrite()) to get 'lost' 2331 * because pages associated with a B_DELWRI bp are marked clean. 2332 * 2333 * We still allow the B_INVAL case to call vfs_vmio_truncate(), even 2334 * if B_DELWRI is set. 2335 */ 2336 if (bp->b_flags & B_DELWRI) 2337 bp->b_flags &= ~B_RELBUF; 2338 2339 /* 2340 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 2341 * constituted, not even NFS buffers now. Two flags effect this. If 2342 * B_INVAL, the struct buf is invalidated but the VM object is kept 2343 * around ( i.e. so it is trivial to reconstitute the buffer later ). 2344 * 2345 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 2346 * invalidated. BIO_ERROR cannot be set for a failed write unless the 2347 * buffer is also B_INVAL because it hits the re-dirtying code above. 2348 * 2349 * Normally we can do this whether a buffer is B_DELWRI or not. If 2350 * the buffer is an NFS buffer, it is tracking piecemeal writes or 2351 * the commit state and we cannot afford to lose the buffer. If the 2352 * buffer has a background write in progress, we need to keep it 2353 * around to prevent it from being reconstituted and starting a second 2354 * background write. 2355 */ 2356 if ((bp->b_flags & B_VMIO) && (bp->b_flags & B_NOCACHE || 2357 (bp->b_ioflags & BIO_ERROR && bp->b_iocmd == BIO_READ)) && 2358 !(bp->b_vp->v_mount != NULL && 2359 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 2360 !vn_isdisk(bp->b_vp, NULL) && (bp->b_flags & B_DELWRI))) { 2361 vfs_vmio_invalidate(bp); 2362 allocbuf(bp, 0); 2363 } 2364 2365 if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0 || 2366 (bp->b_flags & (B_DELWRI | B_NOREUSE)) == B_NOREUSE) { 2367 allocbuf(bp, 0); 2368 bp->b_flags &= ~B_NOREUSE; 2369 if (bp->b_vp != NULL) 2370 brelvp(bp); 2371 } 2372 2373 /* 2374 * If the buffer has junk contents signal it and eventually 2375 * clean up B_DELWRI and diassociate the vnode so that gbincore() 2376 * doesn't find it. 2377 */ 2378 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 2379 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 2380 bp->b_flags |= B_INVAL; 2381 if (bp->b_flags & B_INVAL) { 2382 if (bp->b_flags & B_DELWRI) 2383 bundirty(bp); 2384 if (bp->b_vp) 2385 brelvp(bp); 2386 } 2387 2388 /* buffers with no memory */ 2389 if (bp->b_bufsize == 0) { 2390 buf_free(bp); 2391 return; 2392 } 2393 /* buffers with junk contents */ 2394 if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 2395 (bp->b_ioflags & BIO_ERROR)) { 2396 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 2397 if (bp->b_vflags & BV_BKGRDINPROG) 2398 panic("losing buffer 2"); 2399 qindex = QUEUE_CLEAN; 2400 bp->b_flags |= B_AGE; 2401 /* remaining buffers */ 2402 } else if (bp->b_flags & B_DELWRI) 2403 qindex = QUEUE_DIRTY; 2404 else 2405 qindex = QUEUE_CLEAN; 2406 2407 binsfree(bp, qindex); 2408 2409 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 2410 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 2411 panic("brelse: not dirty"); 2412 /* unlock */ 2413 BUF_UNLOCK(bp); 2414 if (qindex == QUEUE_CLEAN) 2415 bufspace_wakeup(); 2416 } 2417 2418 /* 2419 * Release a buffer back to the appropriate queue but do not try to free 2420 * it. The buffer is expected to be used again soon. 2421 * 2422 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 2423 * biodone() to requeue an async I/O on completion. It is also used when 2424 * known good buffers need to be requeued but we think we may need the data 2425 * again soon. 2426 * 2427 * XXX we should be able to leave the B_RELBUF hint set on completion. 2428 */ 2429 void 2430 bqrelse(struct buf *bp) 2431 { 2432 int qindex; 2433 2434 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2435 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 2436 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 2437 2438 qindex = QUEUE_NONE; 2439 if (BUF_LOCKRECURSED(bp)) { 2440 /* do not release to free list */ 2441 BUF_UNLOCK(bp); 2442 return; 2443 } 2444 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 2445 2446 if (bp->b_flags & B_MANAGED) { 2447 if (bp->b_flags & B_REMFREE) 2448 bremfreef(bp); 2449 goto out; 2450 } 2451 2452 /* buffers with stale but valid contents */ 2453 if ((bp->b_flags & B_DELWRI) != 0 || (bp->b_vflags & (BV_BKGRDINPROG | 2454 BV_BKGRDERR)) == BV_BKGRDERR) { 2455 BO_LOCK(bp->b_bufobj); 2456 bp->b_vflags &= ~BV_BKGRDERR; 2457 BO_UNLOCK(bp->b_bufobj); 2458 qindex = QUEUE_DIRTY; 2459 } else { 2460 if ((bp->b_flags & B_DELWRI) == 0 && 2461 (bp->b_xflags & BX_VNDIRTY)) 2462 panic("bqrelse: not dirty"); 2463 if ((bp->b_flags & B_NOREUSE) != 0) { 2464 brelse(bp); 2465 return; 2466 } 2467 qindex = QUEUE_CLEAN; 2468 } 2469 binsfree(bp, qindex); 2470 2471 out: 2472 /* unlock */ 2473 BUF_UNLOCK(bp); 2474 if (qindex == QUEUE_CLEAN) 2475 bufspace_wakeup(); 2476 } 2477 2478 /* 2479 * Complete I/O to a VMIO backed page. Validate the pages as appropriate, 2480 * restore bogus pages. 2481 */ 2482 static void 2483 vfs_vmio_iodone(struct buf *bp) 2484 { 2485 vm_ooffset_t foff; 2486 vm_page_t m; 2487 vm_object_t obj; 2488 struct vnode *vp; 2489 int bogus, i, iosize; 2490 2491 obj = bp->b_bufobj->bo_object; 2492 KASSERT(obj->paging_in_progress >= bp->b_npages, 2493 ("vfs_vmio_iodone: paging in progress(%d) < b_npages(%d)", 2494 obj->paging_in_progress, bp->b_npages)); 2495 2496 vp = bp->b_vp; 2497 KASSERT(vp->v_holdcnt > 0, 2498 ("vfs_vmio_iodone: vnode %p has zero hold count", vp)); 2499 KASSERT(vp->v_object != NULL, 2500 ("vfs_vmio_iodone: vnode %p has no vm_object", vp)); 2501 2502 foff = bp->b_offset; 2503 KASSERT(bp->b_offset != NOOFFSET, 2504 ("vfs_vmio_iodone: bp %p has no buffer offset", bp)); 2505 2506 bogus = 0; 2507 iosize = bp->b_bcount - bp->b_resid; 2508 VM_OBJECT_WLOCK(obj); 2509 for (i = 0; i < bp->b_npages; i++) { 2510 int resid; 2511 2512 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 2513 if (resid > iosize) 2514 resid = iosize; 2515 2516 /* 2517 * cleanup bogus pages, restoring the originals 2518 */ 2519 m = bp->b_pages[i]; 2520 if (m == bogus_page) { 2521 bogus = 1; 2522 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 2523 if (m == NULL) 2524 panic("biodone: page disappeared!"); 2525 bp->b_pages[i] = m; 2526 } else if ((bp->b_iocmd == BIO_READ) && resid > 0) { 2527 /* 2528 * In the write case, the valid and clean bits are 2529 * already changed correctly ( see bdwrite() ), so we 2530 * only need to do this here in the read case. 2531 */ 2532 KASSERT((m->dirty & vm_page_bits(foff & PAGE_MASK, 2533 resid)) == 0, ("vfs_vmio_iodone: page %p " 2534 "has unexpected dirty bits", m)); 2535 vfs_page_set_valid(bp, foff, m); 2536 } 2537 KASSERT(OFF_TO_IDX(foff) == m->pindex, 2538 ("vfs_vmio_iodone: foff(%jd)/pindex(%ju) mismatch", 2539 (intmax_t)foff, (uintmax_t)m->pindex)); 2540 2541 vm_page_sunbusy(m); 2542 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2543 iosize -= resid; 2544 } 2545 vm_object_pip_wakeupn(obj, bp->b_npages); 2546 VM_OBJECT_WUNLOCK(obj); 2547 if (bogus && buf_mapped(bp)) { 2548 BUF_CHECK_MAPPED(bp); 2549 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 2550 bp->b_pages, bp->b_npages); 2551 } 2552 } 2553 2554 /* 2555 * Unwire a page held by a buf and place it on the appropriate vm queue. 2556 */ 2557 static void 2558 vfs_vmio_unwire(struct buf *bp, vm_page_t m) 2559 { 2560 bool freed; 2561 2562 vm_page_lock(m); 2563 if (vm_page_unwire(m, PQ_NONE)) { 2564 /* 2565 * Determine if the page should be freed before adding 2566 * it to the inactive queue. 2567 */ 2568 if (m->valid == 0) { 2569 freed = !vm_page_busied(m); 2570 if (freed) 2571 vm_page_free(m); 2572 } else if ((bp->b_flags & B_DIRECT) != 0) 2573 freed = vm_page_try_to_free(m); 2574 else 2575 freed = false; 2576 if (!freed) { 2577 /* 2578 * If the page is unlikely to be reused, let the 2579 * VM know. Otherwise, maintain LRU page 2580 * ordering and put the page at the tail of the 2581 * inactive queue. 2582 */ 2583 if ((bp->b_flags & B_NOREUSE) != 0) 2584 vm_page_deactivate_noreuse(m); 2585 else 2586 vm_page_deactivate(m); 2587 } 2588 } 2589 vm_page_unlock(m); 2590 } 2591 2592 /* 2593 * Perform page invalidation when a buffer is released. The fully invalid 2594 * pages will be reclaimed later in vfs_vmio_truncate(). 2595 */ 2596 static void 2597 vfs_vmio_invalidate(struct buf *bp) 2598 { 2599 vm_object_t obj; 2600 vm_page_t m; 2601 int i, resid, poffset, presid; 2602 2603 if (buf_mapped(bp)) { 2604 BUF_CHECK_MAPPED(bp); 2605 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages); 2606 } else 2607 BUF_CHECK_UNMAPPED(bp); 2608 /* 2609 * Get the base offset and length of the buffer. Note that 2610 * in the VMIO case if the buffer block size is not 2611 * page-aligned then b_data pointer may not be page-aligned. 2612 * But our b_pages[] array *IS* page aligned. 2613 * 2614 * block sizes less then DEV_BSIZE (usually 512) are not 2615 * supported due to the page granularity bits (m->valid, 2616 * m->dirty, etc...). 2617 * 2618 * See man buf(9) for more information 2619 */ 2620 obj = bp->b_bufobj->bo_object; 2621 resid = bp->b_bufsize; 2622 poffset = bp->b_offset & PAGE_MASK; 2623 VM_OBJECT_WLOCK(obj); 2624 for (i = 0; i < bp->b_npages; i++) { 2625 m = bp->b_pages[i]; 2626 if (m == bogus_page) 2627 panic("vfs_vmio_invalidate: Unexpected bogus page."); 2628 bp->b_pages[i] = NULL; 2629 2630 presid = resid > (PAGE_SIZE - poffset) ? 2631 (PAGE_SIZE - poffset) : resid; 2632 KASSERT(presid >= 0, ("brelse: extra page")); 2633 while (vm_page_xbusied(m)) { 2634 vm_page_lock(m); 2635 VM_OBJECT_WUNLOCK(obj); 2636 vm_page_busy_sleep(m, "mbncsh"); 2637 VM_OBJECT_WLOCK(obj); 2638 } 2639 if (pmap_page_wired_mappings(m) == 0) 2640 vm_page_set_invalid(m, poffset, presid); 2641 vfs_vmio_unwire(bp, m); 2642 resid -= presid; 2643 poffset = 0; 2644 } 2645 VM_OBJECT_WUNLOCK(obj); 2646 bp->b_npages = 0; 2647 } 2648 2649 /* 2650 * Page-granular truncation of an existing VMIO buffer. 2651 */ 2652 static void 2653 vfs_vmio_truncate(struct buf *bp, int desiredpages) 2654 { 2655 vm_object_t obj; 2656 vm_page_t m; 2657 int i; 2658 2659 if (bp->b_npages == desiredpages) 2660 return; 2661 2662 if (buf_mapped(bp)) { 2663 BUF_CHECK_MAPPED(bp); 2664 pmap_qremove((vm_offset_t)trunc_page((vm_offset_t)bp->b_data) + 2665 (desiredpages << PAGE_SHIFT), bp->b_npages - desiredpages); 2666 } else 2667 BUF_CHECK_UNMAPPED(bp); 2668 obj = bp->b_bufobj->bo_object; 2669 if (obj != NULL) 2670 VM_OBJECT_WLOCK(obj); 2671 for (i = desiredpages; i < bp->b_npages; i++) { 2672 m = bp->b_pages[i]; 2673 KASSERT(m != bogus_page, ("allocbuf: bogus page found")); 2674 bp->b_pages[i] = NULL; 2675 vfs_vmio_unwire(bp, m); 2676 } 2677 if (obj != NULL) 2678 VM_OBJECT_WUNLOCK(obj); 2679 bp->b_npages = desiredpages; 2680 } 2681 2682 /* 2683 * Byte granular extension of VMIO buffers. 2684 */ 2685 static void 2686 vfs_vmio_extend(struct buf *bp, int desiredpages, int size) 2687 { 2688 /* 2689 * We are growing the buffer, possibly in a 2690 * byte-granular fashion. 2691 */ 2692 vm_object_t obj; 2693 vm_offset_t toff; 2694 vm_offset_t tinc; 2695 vm_page_t m; 2696 2697 /* 2698 * Step 1, bring in the VM pages from the object, allocating 2699 * them if necessary. We must clear B_CACHE if these pages 2700 * are not valid for the range covered by the buffer. 2701 */ 2702 obj = bp->b_bufobj->bo_object; 2703 VM_OBJECT_WLOCK(obj); 2704 while (bp->b_npages < desiredpages) { 2705 /* 2706 * We must allocate system pages since blocking 2707 * here could interfere with paging I/O, no 2708 * matter which process we are. 2709 * 2710 * Only exclusive busy can be tested here. 2711 * Blocking on shared busy might lead to 2712 * deadlocks once allocbuf() is called after 2713 * pages are vfs_busy_pages(). 2714 */ 2715 m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) + bp->b_npages, 2716 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM | 2717 VM_ALLOC_WIRED | VM_ALLOC_IGN_SBUSY | 2718 VM_ALLOC_COUNT(desiredpages - bp->b_npages)); 2719 if (m->valid == 0) 2720 bp->b_flags &= ~B_CACHE; 2721 bp->b_pages[bp->b_npages] = m; 2722 ++bp->b_npages; 2723 } 2724 2725 /* 2726 * Step 2. We've loaded the pages into the buffer, 2727 * we have to figure out if we can still have B_CACHE 2728 * set. Note that B_CACHE is set according to the 2729 * byte-granular range ( bcount and size ), not the 2730 * aligned range ( newbsize ). 2731 * 2732 * The VM test is against m->valid, which is DEV_BSIZE 2733 * aligned. Needless to say, the validity of the data 2734 * needs to also be DEV_BSIZE aligned. Note that this 2735 * fails with NFS if the server or some other client 2736 * extends the file's EOF. If our buffer is resized, 2737 * B_CACHE may remain set! XXX 2738 */ 2739 toff = bp->b_bcount; 2740 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 2741 while ((bp->b_flags & B_CACHE) && toff < size) { 2742 vm_pindex_t pi; 2743 2744 if (tinc > (size - toff)) 2745 tinc = size - toff; 2746 pi = ((bp->b_offset & PAGE_MASK) + toff) >> PAGE_SHIFT; 2747 m = bp->b_pages[pi]; 2748 vfs_buf_test_cache(bp, bp->b_offset, toff, tinc, m); 2749 toff += tinc; 2750 tinc = PAGE_SIZE; 2751 } 2752 VM_OBJECT_WUNLOCK(obj); 2753 2754 /* 2755 * Step 3, fixup the KVA pmap. 2756 */ 2757 if (buf_mapped(bp)) 2758 bpmap_qenter(bp); 2759 else 2760 BUF_CHECK_UNMAPPED(bp); 2761 } 2762 2763 /* 2764 * Check to see if a block at a particular lbn is available for a clustered 2765 * write. 2766 */ 2767 static int 2768 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 2769 { 2770 struct buf *bpa; 2771 int match; 2772 2773 match = 0; 2774 2775 /* If the buf isn't in core skip it */ 2776 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 2777 return (0); 2778 2779 /* If the buf is busy we don't want to wait for it */ 2780 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2781 return (0); 2782 2783 /* Only cluster with valid clusterable delayed write buffers */ 2784 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 2785 (B_DELWRI | B_CLUSTEROK)) 2786 goto done; 2787 2788 if (bpa->b_bufsize != size) 2789 goto done; 2790 2791 /* 2792 * Check to see if it is in the expected place on disk and that the 2793 * block has been mapped. 2794 */ 2795 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 2796 match = 1; 2797 done: 2798 BUF_UNLOCK(bpa); 2799 return (match); 2800 } 2801 2802 /* 2803 * vfs_bio_awrite: 2804 * 2805 * Implement clustered async writes for clearing out B_DELWRI buffers. 2806 * This is much better then the old way of writing only one buffer at 2807 * a time. Note that we may not be presented with the buffers in the 2808 * correct order, so we search for the cluster in both directions. 2809 */ 2810 int 2811 vfs_bio_awrite(struct buf *bp) 2812 { 2813 struct bufobj *bo; 2814 int i; 2815 int j; 2816 daddr_t lblkno = bp->b_lblkno; 2817 struct vnode *vp = bp->b_vp; 2818 int ncl; 2819 int nwritten; 2820 int size; 2821 int maxcl; 2822 int gbflags; 2823 2824 bo = &vp->v_bufobj; 2825 gbflags = (bp->b_data == unmapped_buf) ? GB_UNMAPPED : 0; 2826 /* 2827 * right now we support clustered writing only to regular files. If 2828 * we find a clusterable block we could be in the middle of a cluster 2829 * rather then at the beginning. 2830 */ 2831 if ((vp->v_type == VREG) && 2832 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 2833 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 2834 2835 size = vp->v_mount->mnt_stat.f_iosize; 2836 maxcl = MAXPHYS / size; 2837 2838 BO_RLOCK(bo); 2839 for (i = 1; i < maxcl; i++) 2840 if (vfs_bio_clcheck(vp, size, lblkno + i, 2841 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 2842 break; 2843 2844 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 2845 if (vfs_bio_clcheck(vp, size, lblkno - j, 2846 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 2847 break; 2848 BO_RUNLOCK(bo); 2849 --j; 2850 ncl = i + j; 2851 /* 2852 * this is a possible cluster write 2853 */ 2854 if (ncl != 1) { 2855 BUF_UNLOCK(bp); 2856 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl, 2857 gbflags); 2858 return (nwritten); 2859 } 2860 } 2861 bremfree(bp); 2862 bp->b_flags |= B_ASYNC; 2863 /* 2864 * default (old) behavior, writing out only one block 2865 * 2866 * XXX returns b_bufsize instead of b_bcount for nwritten? 2867 */ 2868 nwritten = bp->b_bufsize; 2869 (void) bwrite(bp); 2870 2871 return (nwritten); 2872 } 2873 2874 /* 2875 * getnewbuf_kva: 2876 * 2877 * Allocate KVA for an empty buf header according to gbflags. 2878 */ 2879 static int 2880 getnewbuf_kva(struct buf *bp, int gbflags, int maxsize) 2881 { 2882 2883 if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_UNMAPPED) { 2884 /* 2885 * In order to keep fragmentation sane we only allocate kva 2886 * in BKVASIZE chunks. XXX with vmem we can do page size. 2887 */ 2888 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2889 2890 if (maxsize != bp->b_kvasize && 2891 bufkva_alloc(bp, maxsize, gbflags)) 2892 return (ENOSPC); 2893 } 2894 return (0); 2895 } 2896 2897 /* 2898 * getnewbuf: 2899 * 2900 * Find and initialize a new buffer header, freeing up existing buffers 2901 * in the bufqueues as necessary. The new buffer is returned locked. 2902 * 2903 * We block if: 2904 * We have insufficient buffer headers 2905 * We have insufficient buffer space 2906 * buffer_arena is too fragmented ( space reservation fails ) 2907 * If we have to flush dirty buffers ( but we try to avoid this ) 2908 * 2909 * The caller is responsible for releasing the reserved bufspace after 2910 * allocbuf() is called. 2911 */ 2912 static struct buf * 2913 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int maxsize, int gbflags) 2914 { 2915 struct buf *bp; 2916 bool metadata, reserved; 2917 2918 bp = NULL; 2919 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 2920 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 2921 if (!unmapped_buf_allowed) 2922 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC); 2923 2924 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 || 2925 vp->v_type == VCHR) 2926 metadata = true; 2927 else 2928 metadata = false; 2929 atomic_add_int(&getnewbufcalls, 1); 2930 reserved = false; 2931 do { 2932 if (reserved == false && 2933 bufspace_reserve(maxsize, metadata) != 0) 2934 continue; 2935 reserved = true; 2936 if ((bp = buf_alloc()) == NULL) 2937 continue; 2938 if (getnewbuf_kva(bp, gbflags, maxsize) == 0) 2939 return (bp); 2940 break; 2941 } while(buf_scan(false) == 0); 2942 2943 if (reserved) 2944 atomic_subtract_long(&bufspace, maxsize); 2945 if (bp != NULL) { 2946 bp->b_flags |= B_INVAL; 2947 brelse(bp); 2948 } 2949 bufspace_wait(vp, gbflags, slpflag, slptimeo); 2950 2951 return (NULL); 2952 } 2953 2954 /* 2955 * buf_daemon: 2956 * 2957 * buffer flushing daemon. Buffers are normally flushed by the 2958 * update daemon but if it cannot keep up this process starts to 2959 * take the load in an attempt to prevent getnewbuf() from blocking. 2960 */ 2961 static struct kproc_desc buf_kp = { 2962 "bufdaemon", 2963 buf_daemon, 2964 &bufdaemonproc 2965 }; 2966 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 2967 2968 static int 2969 buf_flush(struct vnode *vp, int target) 2970 { 2971 int flushed; 2972 2973 flushed = flushbufqueues(vp, target, 0); 2974 if (flushed == 0) { 2975 /* 2976 * Could not find any buffers without rollback 2977 * dependencies, so just write the first one 2978 * in the hopes of eventually making progress. 2979 */ 2980 if (vp != NULL && target > 2) 2981 target /= 2; 2982 flushbufqueues(vp, target, 1); 2983 } 2984 return (flushed); 2985 } 2986 2987 static void 2988 buf_daemon() 2989 { 2990 int lodirty; 2991 2992 /* 2993 * This process needs to be suspended prior to shutdown sync. 2994 */ 2995 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2996 SHUTDOWN_PRI_LAST); 2997 2998 /* 2999 * This process is allowed to take the buffer cache to the limit 3000 */ 3001 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 3002 mtx_lock(&bdlock); 3003 for (;;) { 3004 bd_request = 0; 3005 mtx_unlock(&bdlock); 3006 3007 kproc_suspend_check(bufdaemonproc); 3008 lodirty = lodirtybuffers; 3009 if (bd_speedupreq) { 3010 lodirty = numdirtybuffers / 2; 3011 bd_speedupreq = 0; 3012 } 3013 /* 3014 * Do the flush. Limit the amount of in-transit I/O we 3015 * allow to build up, otherwise we would completely saturate 3016 * the I/O system. 3017 */ 3018 while (numdirtybuffers > lodirty) { 3019 if (buf_flush(NULL, numdirtybuffers - lodirty) == 0) 3020 break; 3021 kern_yield(PRI_USER); 3022 } 3023 3024 /* 3025 * Only clear bd_request if we have reached our low water 3026 * mark. The buf_daemon normally waits 1 second and 3027 * then incrementally flushes any dirty buffers that have 3028 * built up, within reason. 3029 * 3030 * If we were unable to hit our low water mark and couldn't 3031 * find any flushable buffers, we sleep for a short period 3032 * to avoid endless loops on unlockable buffers. 3033 */ 3034 mtx_lock(&bdlock); 3035 if (numdirtybuffers <= lodirtybuffers) { 3036 /* 3037 * We reached our low water mark, reset the 3038 * request and sleep until we are needed again. 3039 * The sleep is just so the suspend code works. 3040 */ 3041 bd_request = 0; 3042 /* 3043 * Do an extra wakeup in case dirty threshold 3044 * changed via sysctl and the explicit transition 3045 * out of shortfall was missed. 3046 */ 3047 bdirtywakeup(); 3048 if (runningbufspace <= lorunningspace) 3049 runningwakeup(); 3050 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 3051 } else { 3052 /* 3053 * We couldn't find any flushable dirty buffers but 3054 * still have too many dirty buffers, we 3055 * have to sleep and try again. (rare) 3056 */ 3057 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 3058 } 3059 } 3060 } 3061 3062 /* 3063 * flushbufqueues: 3064 * 3065 * Try to flush a buffer in the dirty queue. We must be careful to 3066 * free up B_INVAL buffers instead of write them, which NFS is 3067 * particularly sensitive to. 3068 */ 3069 static int flushwithdeps = 0; 3070 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 3071 0, "Number of buffers flushed with dependecies that require rollbacks"); 3072 3073 static int 3074 flushbufqueues(struct vnode *lvp, int target, int flushdeps) 3075 { 3076 struct buf *sentinel; 3077 struct vnode *vp; 3078 struct mount *mp; 3079 struct buf *bp; 3080 int hasdeps; 3081 int flushed; 3082 int queue; 3083 int error; 3084 bool unlock; 3085 3086 flushed = 0; 3087 queue = QUEUE_DIRTY; 3088 bp = NULL; 3089 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 3090 sentinel->b_qindex = QUEUE_SENTINEL; 3091 mtx_lock(&bqlocks[queue]); 3092 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist); 3093 mtx_unlock(&bqlocks[queue]); 3094 while (flushed != target) { 3095 maybe_yield(); 3096 mtx_lock(&bqlocks[queue]); 3097 bp = TAILQ_NEXT(sentinel, b_freelist); 3098 if (bp != NULL) { 3099 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 3100 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel, 3101 b_freelist); 3102 } else { 3103 mtx_unlock(&bqlocks[queue]); 3104 break; 3105 } 3106 /* 3107 * Skip sentinels inserted by other invocations of the 3108 * flushbufqueues(), taking care to not reorder them. 3109 * 3110 * Only flush the buffers that belong to the 3111 * vnode locked by the curthread. 3112 */ 3113 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL && 3114 bp->b_vp != lvp)) { 3115 mtx_unlock(&bqlocks[queue]); 3116 continue; 3117 } 3118 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL); 3119 mtx_unlock(&bqlocks[queue]); 3120 if (error != 0) 3121 continue; 3122 3123 /* 3124 * BKGRDINPROG can only be set with the buf and bufobj 3125 * locks both held. We tolerate a race to clear it here. 3126 */ 3127 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 3128 (bp->b_flags & B_DELWRI) == 0) { 3129 BUF_UNLOCK(bp); 3130 continue; 3131 } 3132 if (bp->b_flags & B_INVAL) { 3133 bremfreef(bp); 3134 brelse(bp); 3135 flushed++; 3136 continue; 3137 } 3138 3139 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 3140 if (flushdeps == 0) { 3141 BUF_UNLOCK(bp); 3142 continue; 3143 } 3144 hasdeps = 1; 3145 } else 3146 hasdeps = 0; 3147 /* 3148 * We must hold the lock on a vnode before writing 3149 * one of its buffers. Otherwise we may confuse, or 3150 * in the case of a snapshot vnode, deadlock the 3151 * system. 3152 * 3153 * The lock order here is the reverse of the normal 3154 * of vnode followed by buf lock. This is ok because 3155 * the NOWAIT will prevent deadlock. 3156 */ 3157 vp = bp->b_vp; 3158 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 3159 BUF_UNLOCK(bp); 3160 continue; 3161 } 3162 if (lvp == NULL) { 3163 unlock = true; 3164 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT); 3165 } else { 3166 ASSERT_VOP_LOCKED(vp, "getbuf"); 3167 unlock = false; 3168 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 : 3169 vn_lock(vp, LK_TRYUPGRADE); 3170 } 3171 if (error == 0) { 3172 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 3173 bp, bp->b_vp, bp->b_flags); 3174 if (curproc == bufdaemonproc) { 3175 vfs_bio_awrite(bp); 3176 } else { 3177 bremfree(bp); 3178 bwrite(bp); 3179 notbufdflushes++; 3180 } 3181 vn_finished_write(mp); 3182 if (unlock) 3183 VOP_UNLOCK(vp, 0); 3184 flushwithdeps += hasdeps; 3185 flushed++; 3186 3187 /* 3188 * Sleeping on runningbufspace while holding 3189 * vnode lock leads to deadlock. 3190 */ 3191 if (curproc == bufdaemonproc && 3192 runningbufspace > hirunningspace) 3193 waitrunningbufspace(); 3194 continue; 3195 } 3196 vn_finished_write(mp); 3197 BUF_UNLOCK(bp); 3198 } 3199 mtx_lock(&bqlocks[queue]); 3200 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 3201 mtx_unlock(&bqlocks[queue]); 3202 free(sentinel, M_TEMP); 3203 return (flushed); 3204 } 3205 3206 /* 3207 * Check to see if a block is currently memory resident. 3208 */ 3209 struct buf * 3210 incore(struct bufobj *bo, daddr_t blkno) 3211 { 3212 struct buf *bp; 3213 3214 BO_RLOCK(bo); 3215 bp = gbincore(bo, blkno); 3216 BO_RUNLOCK(bo); 3217 return (bp); 3218 } 3219 3220 /* 3221 * Returns true if no I/O is needed to access the 3222 * associated VM object. This is like incore except 3223 * it also hunts around in the VM system for the data. 3224 */ 3225 3226 static int 3227 inmem(struct vnode * vp, daddr_t blkno) 3228 { 3229 vm_object_t obj; 3230 vm_offset_t toff, tinc, size; 3231 vm_page_t m; 3232 vm_ooffset_t off; 3233 3234 ASSERT_VOP_LOCKED(vp, "inmem"); 3235 3236 if (incore(&vp->v_bufobj, blkno)) 3237 return 1; 3238 if (vp->v_mount == NULL) 3239 return 0; 3240 obj = vp->v_object; 3241 if (obj == NULL) 3242 return (0); 3243 3244 size = PAGE_SIZE; 3245 if (size > vp->v_mount->mnt_stat.f_iosize) 3246 size = vp->v_mount->mnt_stat.f_iosize; 3247 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 3248 3249 VM_OBJECT_RLOCK(obj); 3250 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 3251 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 3252 if (!m) 3253 goto notinmem; 3254 tinc = size; 3255 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 3256 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 3257 if (vm_page_is_valid(m, 3258 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 3259 goto notinmem; 3260 } 3261 VM_OBJECT_RUNLOCK(obj); 3262 return 1; 3263 3264 notinmem: 3265 VM_OBJECT_RUNLOCK(obj); 3266 return (0); 3267 } 3268 3269 /* 3270 * Set the dirty range for a buffer based on the status of the dirty 3271 * bits in the pages comprising the buffer. The range is limited 3272 * to the size of the buffer. 3273 * 3274 * Tell the VM system that the pages associated with this buffer 3275 * are clean. This is used for delayed writes where the data is 3276 * going to go to disk eventually without additional VM intevention. 3277 * 3278 * Note that while we only really need to clean through to b_bcount, we 3279 * just go ahead and clean through to b_bufsize. 3280 */ 3281 static void 3282 vfs_clean_pages_dirty_buf(struct buf *bp) 3283 { 3284 vm_ooffset_t foff, noff, eoff; 3285 vm_page_t m; 3286 int i; 3287 3288 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 3289 return; 3290 3291 foff = bp->b_offset; 3292 KASSERT(bp->b_offset != NOOFFSET, 3293 ("vfs_clean_pages_dirty_buf: no buffer offset")); 3294 3295 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 3296 vfs_drain_busy_pages(bp); 3297 vfs_setdirty_locked_object(bp); 3298 for (i = 0; i < bp->b_npages; i++) { 3299 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3300 eoff = noff; 3301 if (eoff > bp->b_offset + bp->b_bufsize) 3302 eoff = bp->b_offset + bp->b_bufsize; 3303 m = bp->b_pages[i]; 3304 vfs_page_set_validclean(bp, foff, m); 3305 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3306 foff = noff; 3307 } 3308 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 3309 } 3310 3311 static void 3312 vfs_setdirty_locked_object(struct buf *bp) 3313 { 3314 vm_object_t object; 3315 int i; 3316 3317 object = bp->b_bufobj->bo_object; 3318 VM_OBJECT_ASSERT_WLOCKED(object); 3319 3320 /* 3321 * We qualify the scan for modified pages on whether the 3322 * object has been flushed yet. 3323 */ 3324 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) { 3325 vm_offset_t boffset; 3326 vm_offset_t eoffset; 3327 3328 /* 3329 * test the pages to see if they have been modified directly 3330 * by users through the VM system. 3331 */ 3332 for (i = 0; i < bp->b_npages; i++) 3333 vm_page_test_dirty(bp->b_pages[i]); 3334 3335 /* 3336 * Calculate the encompassing dirty range, boffset and eoffset, 3337 * (eoffset - boffset) bytes. 3338 */ 3339 3340 for (i = 0; i < bp->b_npages; i++) { 3341 if (bp->b_pages[i]->dirty) 3342 break; 3343 } 3344 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3345 3346 for (i = bp->b_npages - 1; i >= 0; --i) { 3347 if (bp->b_pages[i]->dirty) { 3348 break; 3349 } 3350 } 3351 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3352 3353 /* 3354 * Fit it to the buffer. 3355 */ 3356 3357 if (eoffset > bp->b_bcount) 3358 eoffset = bp->b_bcount; 3359 3360 /* 3361 * If we have a good dirty range, merge with the existing 3362 * dirty range. 3363 */ 3364 3365 if (boffset < eoffset) { 3366 if (bp->b_dirtyoff > boffset) 3367 bp->b_dirtyoff = boffset; 3368 if (bp->b_dirtyend < eoffset) 3369 bp->b_dirtyend = eoffset; 3370 } 3371 } 3372 } 3373 3374 /* 3375 * Allocate the KVA mapping for an existing buffer. 3376 * If an unmapped buffer is provided but a mapped buffer is requested, take 3377 * also care to properly setup mappings between pages and KVA. 3378 */ 3379 static void 3380 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags) 3381 { 3382 int bsize, maxsize, need_mapping, need_kva; 3383 off_t offset; 3384 3385 need_mapping = bp->b_data == unmapped_buf && 3386 (gbflags & GB_UNMAPPED) == 0; 3387 need_kva = bp->b_kvabase == unmapped_buf && 3388 bp->b_data == unmapped_buf && 3389 (gbflags & GB_KVAALLOC) != 0; 3390 if (!need_mapping && !need_kva) 3391 return; 3392 3393 BUF_CHECK_UNMAPPED(bp); 3394 3395 if (need_mapping && bp->b_kvabase != unmapped_buf) { 3396 /* 3397 * Buffer is not mapped, but the KVA was already 3398 * reserved at the time of the instantiation. Use the 3399 * allocated space. 3400 */ 3401 goto has_addr; 3402 } 3403 3404 /* 3405 * Calculate the amount of the address space we would reserve 3406 * if the buffer was mapped. 3407 */ 3408 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize; 3409 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3410 offset = blkno * bsize; 3411 maxsize = size + (offset & PAGE_MASK); 3412 maxsize = imax(maxsize, bsize); 3413 3414 while (bufkva_alloc(bp, maxsize, gbflags) != 0) { 3415 if ((gbflags & GB_NOWAIT_BD) != 0) { 3416 /* 3417 * XXXKIB: defragmentation cannot 3418 * succeed, not sure what else to do. 3419 */ 3420 panic("GB_NOWAIT_BD and GB_UNMAPPED %p", bp); 3421 } 3422 atomic_add_int(&mappingrestarts, 1); 3423 bufspace_wait(bp->b_vp, gbflags, 0, 0); 3424 } 3425 has_addr: 3426 if (need_mapping) { 3427 /* b_offset is handled by bpmap_qenter. */ 3428 bp->b_data = bp->b_kvabase; 3429 BUF_CHECK_MAPPED(bp); 3430 bpmap_qenter(bp); 3431 } 3432 } 3433 3434 /* 3435 * getblk: 3436 * 3437 * Get a block given a specified block and offset into a file/device. 3438 * The buffers B_DONE bit will be cleared on return, making it almost 3439 * ready for an I/O initiation. B_INVAL may or may not be set on 3440 * return. The caller should clear B_INVAL prior to initiating a 3441 * READ. 3442 * 3443 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 3444 * an existing buffer. 3445 * 3446 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 3447 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 3448 * and then cleared based on the backing VM. If the previous buffer is 3449 * non-0-sized but invalid, B_CACHE will be cleared. 3450 * 3451 * If getblk() must create a new buffer, the new buffer is returned with 3452 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 3453 * case it is returned with B_INVAL clear and B_CACHE set based on the 3454 * backing VM. 3455 * 3456 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 3457 * B_CACHE bit is clear. 3458 * 3459 * What this means, basically, is that the caller should use B_CACHE to 3460 * determine whether the buffer is fully valid or not and should clear 3461 * B_INVAL prior to issuing a read. If the caller intends to validate 3462 * the buffer by loading its data area with something, the caller needs 3463 * to clear B_INVAL. If the caller does this without issuing an I/O, 3464 * the caller should set B_CACHE ( as an optimization ), else the caller 3465 * should issue the I/O and biodone() will set B_CACHE if the I/O was 3466 * a write attempt or if it was a successful read. If the caller 3467 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 3468 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 3469 */ 3470 struct buf * 3471 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3472 int flags) 3473 { 3474 struct buf *bp; 3475 struct bufobj *bo; 3476 int bsize, error, maxsize, vmio; 3477 off_t offset; 3478 3479 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 3480 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3481 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3482 ASSERT_VOP_LOCKED(vp, "getblk"); 3483 if (size > MAXBCACHEBUF) 3484 panic("getblk: size(%d) > MAXBCACHEBUF(%d)\n", size, 3485 MAXBCACHEBUF); 3486 if (!unmapped_buf_allowed) 3487 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3488 3489 bo = &vp->v_bufobj; 3490 loop: 3491 BO_RLOCK(bo); 3492 bp = gbincore(bo, blkno); 3493 if (bp != NULL) { 3494 int lockflags; 3495 /* 3496 * Buffer is in-core. If the buffer is not busy nor managed, 3497 * it must be on a queue. 3498 */ 3499 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 3500 3501 if (flags & GB_LOCK_NOWAIT) 3502 lockflags |= LK_NOWAIT; 3503 3504 error = BUF_TIMELOCK(bp, lockflags, 3505 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo); 3506 3507 /* 3508 * If we slept and got the lock we have to restart in case 3509 * the buffer changed identities. 3510 */ 3511 if (error == ENOLCK) 3512 goto loop; 3513 /* We timed out or were interrupted. */ 3514 else if (error) 3515 return (NULL); 3516 /* If recursed, assume caller knows the rules. */ 3517 else if (BUF_LOCKRECURSED(bp)) 3518 goto end; 3519 3520 /* 3521 * The buffer is locked. B_CACHE is cleared if the buffer is 3522 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 3523 * and for a VMIO buffer B_CACHE is adjusted according to the 3524 * backing VM cache. 3525 */ 3526 if (bp->b_flags & B_INVAL) 3527 bp->b_flags &= ~B_CACHE; 3528 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 3529 bp->b_flags |= B_CACHE; 3530 if (bp->b_flags & B_MANAGED) 3531 MPASS(bp->b_qindex == QUEUE_NONE); 3532 else 3533 bremfree(bp); 3534 3535 /* 3536 * check for size inconsistencies for non-VMIO case. 3537 */ 3538 if (bp->b_bcount != size) { 3539 if ((bp->b_flags & B_VMIO) == 0 || 3540 (size > bp->b_kvasize)) { 3541 if (bp->b_flags & B_DELWRI) { 3542 bp->b_flags |= B_NOCACHE; 3543 bwrite(bp); 3544 } else { 3545 if (LIST_EMPTY(&bp->b_dep)) { 3546 bp->b_flags |= B_RELBUF; 3547 brelse(bp); 3548 } else { 3549 bp->b_flags |= B_NOCACHE; 3550 bwrite(bp); 3551 } 3552 } 3553 goto loop; 3554 } 3555 } 3556 3557 /* 3558 * Handle the case of unmapped buffer which should 3559 * become mapped, or the buffer for which KVA 3560 * reservation is requested. 3561 */ 3562 bp_unmapped_get_kva(bp, blkno, size, flags); 3563 3564 /* 3565 * If the size is inconsistent in the VMIO case, we can resize 3566 * the buffer. This might lead to B_CACHE getting set or 3567 * cleared. If the size has not changed, B_CACHE remains 3568 * unchanged from its previous state. 3569 */ 3570 allocbuf(bp, size); 3571 3572 KASSERT(bp->b_offset != NOOFFSET, 3573 ("getblk: no buffer offset")); 3574 3575 /* 3576 * A buffer with B_DELWRI set and B_CACHE clear must 3577 * be committed before we can return the buffer in 3578 * order to prevent the caller from issuing a read 3579 * ( due to B_CACHE not being set ) and overwriting 3580 * it. 3581 * 3582 * Most callers, including NFS and FFS, need this to 3583 * operate properly either because they assume they 3584 * can issue a read if B_CACHE is not set, or because 3585 * ( for example ) an uncached B_DELWRI might loop due 3586 * to softupdates re-dirtying the buffer. In the latter 3587 * case, B_CACHE is set after the first write completes, 3588 * preventing further loops. 3589 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 3590 * above while extending the buffer, we cannot allow the 3591 * buffer to remain with B_CACHE set after the write 3592 * completes or it will represent a corrupt state. To 3593 * deal with this we set B_NOCACHE to scrap the buffer 3594 * after the write. 3595 * 3596 * We might be able to do something fancy, like setting 3597 * B_CACHE in bwrite() except if B_DELWRI is already set, 3598 * so the below call doesn't set B_CACHE, but that gets real 3599 * confusing. This is much easier. 3600 */ 3601 3602 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 3603 bp->b_flags |= B_NOCACHE; 3604 bwrite(bp); 3605 goto loop; 3606 } 3607 bp->b_flags &= ~B_DONE; 3608 } else { 3609 /* 3610 * Buffer is not in-core, create new buffer. The buffer 3611 * returned by getnewbuf() is locked. Note that the returned 3612 * buffer is also considered valid (not marked B_INVAL). 3613 */ 3614 BO_RUNLOCK(bo); 3615 /* 3616 * If the user does not want us to create the buffer, bail out 3617 * here. 3618 */ 3619 if (flags & GB_NOCREAT) 3620 return NULL; 3621 if (numfreebuffers == 0 && TD_IS_IDLETHREAD(curthread)) 3622 return NULL; 3623 3624 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize; 3625 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3626 offset = blkno * bsize; 3627 vmio = vp->v_object != NULL; 3628 if (vmio) { 3629 maxsize = size + (offset & PAGE_MASK); 3630 } else { 3631 maxsize = size; 3632 /* Do not allow non-VMIO notmapped buffers. */ 3633 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3634 } 3635 maxsize = imax(maxsize, bsize); 3636 3637 bp = getnewbuf(vp, slpflag, slptimeo, maxsize, flags); 3638 if (bp == NULL) { 3639 if (slpflag || slptimeo) 3640 return NULL; 3641 /* 3642 * XXX This is here until the sleep path is diagnosed 3643 * enough to work under very low memory conditions. 3644 * 3645 * There's an issue on low memory, 4BSD+non-preempt 3646 * systems (eg MIPS routers with 32MB RAM) where buffer 3647 * exhaustion occurs without sleeping for buffer 3648 * reclaimation. This just sticks in a loop and 3649 * constantly attempts to allocate a buffer, which 3650 * hits exhaustion and tries to wakeup bufdaemon. 3651 * This never happens because we never yield. 3652 * 3653 * The real solution is to identify and fix these cases 3654 * so we aren't effectively busy-waiting in a loop 3655 * until the reclaimation path has cycles to run. 3656 */ 3657 kern_yield(PRI_USER); 3658 goto loop; 3659 } 3660 3661 /* 3662 * This code is used to make sure that a buffer is not 3663 * created while the getnewbuf routine is blocked. 3664 * This can be a problem whether the vnode is locked or not. 3665 * If the buffer is created out from under us, we have to 3666 * throw away the one we just created. 3667 * 3668 * Note: this must occur before we associate the buffer 3669 * with the vp especially considering limitations in 3670 * the splay tree implementation when dealing with duplicate 3671 * lblkno's. 3672 */ 3673 BO_LOCK(bo); 3674 if (gbincore(bo, blkno)) { 3675 BO_UNLOCK(bo); 3676 bp->b_flags |= B_INVAL; 3677 brelse(bp); 3678 bufspace_release(maxsize); 3679 goto loop; 3680 } 3681 3682 /* 3683 * Insert the buffer into the hash, so that it can 3684 * be found by incore. 3685 */ 3686 bp->b_blkno = bp->b_lblkno = blkno; 3687 bp->b_offset = offset; 3688 bgetvp(vp, bp); 3689 BO_UNLOCK(bo); 3690 3691 /* 3692 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 3693 * buffer size starts out as 0, B_CACHE will be set by 3694 * allocbuf() for the VMIO case prior to it testing the 3695 * backing store for validity. 3696 */ 3697 3698 if (vmio) { 3699 bp->b_flags |= B_VMIO; 3700 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 3701 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 3702 bp, vp->v_object, bp->b_bufobj->bo_object)); 3703 } else { 3704 bp->b_flags &= ~B_VMIO; 3705 KASSERT(bp->b_bufobj->bo_object == NULL, 3706 ("ARGH! has b_bufobj->bo_object %p %p\n", 3707 bp, bp->b_bufobj->bo_object)); 3708 BUF_CHECK_MAPPED(bp); 3709 } 3710 3711 allocbuf(bp, size); 3712 bufspace_release(maxsize); 3713 bp->b_flags &= ~B_DONE; 3714 } 3715 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 3716 BUF_ASSERT_HELD(bp); 3717 end: 3718 KASSERT(bp->b_bufobj == bo, 3719 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 3720 return (bp); 3721 } 3722 3723 /* 3724 * Get an empty, disassociated buffer of given size. The buffer is initially 3725 * set to B_INVAL. 3726 */ 3727 struct buf * 3728 geteblk(int size, int flags) 3729 { 3730 struct buf *bp; 3731 int maxsize; 3732 3733 maxsize = (size + BKVAMASK) & ~BKVAMASK; 3734 while ((bp = getnewbuf(NULL, 0, 0, maxsize, flags)) == NULL) { 3735 if ((flags & GB_NOWAIT_BD) && 3736 (curthread->td_pflags & TDP_BUFNEED) != 0) 3737 return (NULL); 3738 } 3739 allocbuf(bp, size); 3740 bufspace_release(maxsize); 3741 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 3742 BUF_ASSERT_HELD(bp); 3743 return (bp); 3744 } 3745 3746 /* 3747 * Truncate the backing store for a non-vmio buffer. 3748 */ 3749 static void 3750 vfs_nonvmio_truncate(struct buf *bp, int newbsize) 3751 { 3752 3753 if (bp->b_flags & B_MALLOC) { 3754 /* 3755 * malloced buffers are not shrunk 3756 */ 3757 if (newbsize == 0) { 3758 bufmallocadjust(bp, 0); 3759 free(bp->b_data, M_BIOBUF); 3760 bp->b_data = bp->b_kvabase; 3761 bp->b_flags &= ~B_MALLOC; 3762 } 3763 return; 3764 } 3765 vm_hold_free_pages(bp, newbsize); 3766 bufspace_adjust(bp, newbsize); 3767 } 3768 3769 /* 3770 * Extend the backing for a non-VMIO buffer. 3771 */ 3772 static void 3773 vfs_nonvmio_extend(struct buf *bp, int newbsize) 3774 { 3775 caddr_t origbuf; 3776 int origbufsize; 3777 3778 /* 3779 * We only use malloced memory on the first allocation. 3780 * and revert to page-allocated memory when the buffer 3781 * grows. 3782 * 3783 * There is a potential smp race here that could lead 3784 * to bufmallocspace slightly passing the max. It 3785 * is probably extremely rare and not worth worrying 3786 * over. 3787 */ 3788 if (bp->b_bufsize == 0 && newbsize <= PAGE_SIZE/2 && 3789 bufmallocspace < maxbufmallocspace) { 3790 bp->b_data = malloc(newbsize, M_BIOBUF, M_WAITOK); 3791 bp->b_flags |= B_MALLOC; 3792 bufmallocadjust(bp, newbsize); 3793 return; 3794 } 3795 3796 /* 3797 * If the buffer is growing on its other-than-first 3798 * allocation then we revert to the page-allocation 3799 * scheme. 3800 */ 3801 origbuf = NULL; 3802 origbufsize = 0; 3803 if (bp->b_flags & B_MALLOC) { 3804 origbuf = bp->b_data; 3805 origbufsize = bp->b_bufsize; 3806 bp->b_data = bp->b_kvabase; 3807 bufmallocadjust(bp, 0); 3808 bp->b_flags &= ~B_MALLOC; 3809 newbsize = round_page(newbsize); 3810 } 3811 vm_hold_load_pages(bp, (vm_offset_t) bp->b_data + bp->b_bufsize, 3812 (vm_offset_t) bp->b_data + newbsize); 3813 if (origbuf != NULL) { 3814 bcopy(origbuf, bp->b_data, origbufsize); 3815 free(origbuf, M_BIOBUF); 3816 } 3817 bufspace_adjust(bp, newbsize); 3818 } 3819 3820 /* 3821 * This code constitutes the buffer memory from either anonymous system 3822 * memory (in the case of non-VMIO operations) or from an associated 3823 * VM object (in the case of VMIO operations). This code is able to 3824 * resize a buffer up or down. 3825 * 3826 * Note that this code is tricky, and has many complications to resolve 3827 * deadlock or inconsistent data situations. Tread lightly!!! 3828 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 3829 * the caller. Calling this code willy nilly can result in the loss of data. 3830 * 3831 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 3832 * B_CACHE for the non-VMIO case. 3833 */ 3834 int 3835 allocbuf(struct buf *bp, int size) 3836 { 3837 int newbsize; 3838 3839 BUF_ASSERT_HELD(bp); 3840 3841 if (bp->b_bcount == size) 3842 return (1); 3843 3844 if (bp->b_kvasize != 0 && bp->b_kvasize < size) 3845 panic("allocbuf: buffer too small"); 3846 3847 newbsize = roundup2(size, DEV_BSIZE); 3848 if ((bp->b_flags & B_VMIO) == 0) { 3849 if ((bp->b_flags & B_MALLOC) == 0) 3850 newbsize = round_page(newbsize); 3851 /* 3852 * Just get anonymous memory from the kernel. Don't 3853 * mess with B_CACHE. 3854 */ 3855 if (newbsize < bp->b_bufsize) 3856 vfs_nonvmio_truncate(bp, newbsize); 3857 else if (newbsize > bp->b_bufsize) 3858 vfs_nonvmio_extend(bp, newbsize); 3859 } else { 3860 int desiredpages; 3861 3862 desiredpages = (size == 0) ? 0 : 3863 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 3864 3865 if (bp->b_flags & B_MALLOC) 3866 panic("allocbuf: VMIO buffer can't be malloced"); 3867 /* 3868 * Set B_CACHE initially if buffer is 0 length or will become 3869 * 0-length. 3870 */ 3871 if (size == 0 || bp->b_bufsize == 0) 3872 bp->b_flags |= B_CACHE; 3873 3874 if (newbsize < bp->b_bufsize) 3875 vfs_vmio_truncate(bp, desiredpages); 3876 /* XXX This looks as if it should be newbsize > b_bufsize */ 3877 else if (size > bp->b_bcount) 3878 vfs_vmio_extend(bp, desiredpages, size); 3879 bufspace_adjust(bp, newbsize); 3880 } 3881 bp->b_bcount = size; /* requested buffer size. */ 3882 return (1); 3883 } 3884 3885 extern int inflight_transient_maps; 3886 3887 void 3888 biodone(struct bio *bp) 3889 { 3890 struct mtx *mtxp; 3891 void (*done)(struct bio *); 3892 vm_offset_t start, end; 3893 3894 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) { 3895 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING; 3896 bp->bio_flags |= BIO_UNMAPPED; 3897 start = trunc_page((vm_offset_t)bp->bio_data); 3898 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length); 3899 bp->bio_data = unmapped_buf; 3900 pmap_qremove(start, OFF_TO_IDX(end - start)); 3901 vmem_free(transient_arena, start, end - start); 3902 atomic_add_int(&inflight_transient_maps, -1); 3903 } 3904 done = bp->bio_done; 3905 if (done == NULL) { 3906 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3907 mtx_lock(mtxp); 3908 bp->bio_flags |= BIO_DONE; 3909 wakeup(bp); 3910 mtx_unlock(mtxp); 3911 } else { 3912 bp->bio_flags |= BIO_DONE; 3913 done(bp); 3914 } 3915 } 3916 3917 /* 3918 * Wait for a BIO to finish. 3919 */ 3920 int 3921 biowait(struct bio *bp, const char *wchan) 3922 { 3923 struct mtx *mtxp; 3924 3925 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3926 mtx_lock(mtxp); 3927 while ((bp->bio_flags & BIO_DONE) == 0) 3928 msleep(bp, mtxp, PRIBIO, wchan, 0); 3929 mtx_unlock(mtxp); 3930 if (bp->bio_error != 0) 3931 return (bp->bio_error); 3932 if (!(bp->bio_flags & BIO_ERROR)) 3933 return (0); 3934 return (EIO); 3935 } 3936 3937 void 3938 biofinish(struct bio *bp, struct devstat *stat, int error) 3939 { 3940 3941 if (error) { 3942 bp->bio_error = error; 3943 bp->bio_flags |= BIO_ERROR; 3944 } 3945 if (stat != NULL) 3946 devstat_end_transaction_bio(stat, bp); 3947 biodone(bp); 3948 } 3949 3950 /* 3951 * bufwait: 3952 * 3953 * Wait for buffer I/O completion, returning error status. The buffer 3954 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3955 * error and cleared. 3956 */ 3957 int 3958 bufwait(struct buf *bp) 3959 { 3960 if (bp->b_iocmd == BIO_READ) 3961 bwait(bp, PRIBIO, "biord"); 3962 else 3963 bwait(bp, PRIBIO, "biowr"); 3964 if (bp->b_flags & B_EINTR) { 3965 bp->b_flags &= ~B_EINTR; 3966 return (EINTR); 3967 } 3968 if (bp->b_ioflags & BIO_ERROR) { 3969 return (bp->b_error ? bp->b_error : EIO); 3970 } else { 3971 return (0); 3972 } 3973 } 3974 3975 /* 3976 * bufdone: 3977 * 3978 * Finish I/O on a buffer, optionally calling a completion function. 3979 * This is usually called from an interrupt so process blocking is 3980 * not allowed. 3981 * 3982 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3983 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3984 * assuming B_INVAL is clear. 3985 * 3986 * For the VMIO case, we set B_CACHE if the op was a read and no 3987 * read error occurred, or if the op was a write. B_CACHE is never 3988 * set if the buffer is invalid or otherwise uncacheable. 3989 * 3990 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3991 * initiator to leave B_INVAL set to brelse the buffer out of existence 3992 * in the biodone routine. 3993 */ 3994 void 3995 bufdone(struct buf *bp) 3996 { 3997 struct bufobj *dropobj; 3998 void (*biodone)(struct buf *); 3999 4000 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 4001 dropobj = NULL; 4002 4003 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 4004 BUF_ASSERT_HELD(bp); 4005 4006 runningbufwakeup(bp); 4007 if (bp->b_iocmd == BIO_WRITE) 4008 dropobj = bp->b_bufobj; 4009 /* call optional completion function if requested */ 4010 if (bp->b_iodone != NULL) { 4011 biodone = bp->b_iodone; 4012 bp->b_iodone = NULL; 4013 (*biodone) (bp); 4014 if (dropobj) 4015 bufobj_wdrop(dropobj); 4016 return; 4017 } 4018 4019 bufdone_finish(bp); 4020 4021 if (dropobj) 4022 bufobj_wdrop(dropobj); 4023 } 4024 4025 void 4026 bufdone_finish(struct buf *bp) 4027 { 4028 BUF_ASSERT_HELD(bp); 4029 4030 if (!LIST_EMPTY(&bp->b_dep)) 4031 buf_complete(bp); 4032 4033 if (bp->b_flags & B_VMIO) { 4034 /* 4035 * Set B_CACHE if the op was a normal read and no error 4036 * occurred. B_CACHE is set for writes in the b*write() 4037 * routines. 4038 */ 4039 if (bp->b_iocmd == BIO_READ && 4040 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 4041 !(bp->b_ioflags & BIO_ERROR)) 4042 bp->b_flags |= B_CACHE; 4043 vfs_vmio_iodone(bp); 4044 } 4045 4046 /* 4047 * For asynchronous completions, release the buffer now. The brelse 4048 * will do a wakeup there if necessary - so no need to do a wakeup 4049 * here in the async case. The sync case always needs to do a wakeup. 4050 */ 4051 if (bp->b_flags & B_ASYNC) { 4052 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || 4053 (bp->b_ioflags & BIO_ERROR)) 4054 brelse(bp); 4055 else 4056 bqrelse(bp); 4057 } else 4058 bdone(bp); 4059 } 4060 4061 /* 4062 * This routine is called in lieu of iodone in the case of 4063 * incomplete I/O. This keeps the busy status for pages 4064 * consistent. 4065 */ 4066 void 4067 vfs_unbusy_pages(struct buf *bp) 4068 { 4069 int i; 4070 vm_object_t obj; 4071 vm_page_t m; 4072 4073 runningbufwakeup(bp); 4074 if (!(bp->b_flags & B_VMIO)) 4075 return; 4076 4077 obj = bp->b_bufobj->bo_object; 4078 VM_OBJECT_WLOCK(obj); 4079 for (i = 0; i < bp->b_npages; i++) { 4080 m = bp->b_pages[i]; 4081 if (m == bogus_page) { 4082 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 4083 if (!m) 4084 panic("vfs_unbusy_pages: page missing\n"); 4085 bp->b_pages[i] = m; 4086 if (buf_mapped(bp)) { 4087 BUF_CHECK_MAPPED(bp); 4088 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4089 bp->b_pages, bp->b_npages); 4090 } else 4091 BUF_CHECK_UNMAPPED(bp); 4092 } 4093 vm_page_sunbusy(m); 4094 } 4095 vm_object_pip_wakeupn(obj, bp->b_npages); 4096 VM_OBJECT_WUNLOCK(obj); 4097 } 4098 4099 /* 4100 * vfs_page_set_valid: 4101 * 4102 * Set the valid bits in a page based on the supplied offset. The 4103 * range is restricted to the buffer's size. 4104 * 4105 * This routine is typically called after a read completes. 4106 */ 4107 static void 4108 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4109 { 4110 vm_ooffset_t eoff; 4111 4112 /* 4113 * Compute the end offset, eoff, such that [off, eoff) does not span a 4114 * page boundary and eoff is not greater than the end of the buffer. 4115 * The end of the buffer, in this case, is our file EOF, not the 4116 * allocation size of the buffer. 4117 */ 4118 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 4119 if (eoff > bp->b_offset + bp->b_bcount) 4120 eoff = bp->b_offset + bp->b_bcount; 4121 4122 /* 4123 * Set valid range. This is typically the entire buffer and thus the 4124 * entire page. 4125 */ 4126 if (eoff > off) 4127 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off); 4128 } 4129 4130 /* 4131 * vfs_page_set_validclean: 4132 * 4133 * Set the valid bits and clear the dirty bits in a page based on the 4134 * supplied offset. The range is restricted to the buffer's size. 4135 */ 4136 static void 4137 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4138 { 4139 vm_ooffset_t soff, eoff; 4140 4141 /* 4142 * Start and end offsets in buffer. eoff - soff may not cross a 4143 * page boundary or cross the end of the buffer. The end of the 4144 * buffer, in this case, is our file EOF, not the allocation size 4145 * of the buffer. 4146 */ 4147 soff = off; 4148 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4149 if (eoff > bp->b_offset + bp->b_bcount) 4150 eoff = bp->b_offset + bp->b_bcount; 4151 4152 /* 4153 * Set valid range. This is typically the entire buffer and thus the 4154 * entire page. 4155 */ 4156 if (eoff > soff) { 4157 vm_page_set_validclean( 4158 m, 4159 (vm_offset_t) (soff & PAGE_MASK), 4160 (vm_offset_t) (eoff - soff) 4161 ); 4162 } 4163 } 4164 4165 /* 4166 * Ensure that all buffer pages are not exclusive busied. If any page is 4167 * exclusive busy, drain it. 4168 */ 4169 void 4170 vfs_drain_busy_pages(struct buf *bp) 4171 { 4172 vm_page_t m; 4173 int i, last_busied; 4174 4175 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object); 4176 last_busied = 0; 4177 for (i = 0; i < bp->b_npages; i++) { 4178 m = bp->b_pages[i]; 4179 if (vm_page_xbusied(m)) { 4180 for (; last_busied < i; last_busied++) 4181 vm_page_sbusy(bp->b_pages[last_busied]); 4182 while (vm_page_xbusied(m)) { 4183 vm_page_lock(m); 4184 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4185 vm_page_busy_sleep(m, "vbpage"); 4186 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4187 } 4188 } 4189 } 4190 for (i = 0; i < last_busied; i++) 4191 vm_page_sunbusy(bp->b_pages[i]); 4192 } 4193 4194 /* 4195 * This routine is called before a device strategy routine. 4196 * It is used to tell the VM system that paging I/O is in 4197 * progress, and treat the pages associated with the buffer 4198 * almost as being exclusive busy. Also the object paging_in_progress 4199 * flag is handled to make sure that the object doesn't become 4200 * inconsistent. 4201 * 4202 * Since I/O has not been initiated yet, certain buffer flags 4203 * such as BIO_ERROR or B_INVAL may be in an inconsistent state 4204 * and should be ignored. 4205 */ 4206 void 4207 vfs_busy_pages(struct buf *bp, int clear_modify) 4208 { 4209 int i, bogus; 4210 vm_object_t obj; 4211 vm_ooffset_t foff; 4212 vm_page_t m; 4213 4214 if (!(bp->b_flags & B_VMIO)) 4215 return; 4216 4217 obj = bp->b_bufobj->bo_object; 4218 foff = bp->b_offset; 4219 KASSERT(bp->b_offset != NOOFFSET, 4220 ("vfs_busy_pages: no buffer offset")); 4221 VM_OBJECT_WLOCK(obj); 4222 vfs_drain_busy_pages(bp); 4223 if (bp->b_bufsize != 0) 4224 vfs_setdirty_locked_object(bp); 4225 bogus = 0; 4226 for (i = 0; i < bp->b_npages; i++) { 4227 m = bp->b_pages[i]; 4228 4229 if ((bp->b_flags & B_CLUSTER) == 0) { 4230 vm_object_pip_add(obj, 1); 4231 vm_page_sbusy(m); 4232 } 4233 /* 4234 * When readying a buffer for a read ( i.e 4235 * clear_modify == 0 ), it is important to do 4236 * bogus_page replacement for valid pages in 4237 * partially instantiated buffers. Partially 4238 * instantiated buffers can, in turn, occur when 4239 * reconstituting a buffer from its VM backing store 4240 * base. We only have to do this if B_CACHE is 4241 * clear ( which causes the I/O to occur in the 4242 * first place ). The replacement prevents the read 4243 * I/O from overwriting potentially dirty VM-backed 4244 * pages. XXX bogus page replacement is, uh, bogus. 4245 * It may not work properly with small-block devices. 4246 * We need to find a better way. 4247 */ 4248 if (clear_modify) { 4249 pmap_remove_write(m); 4250 vfs_page_set_validclean(bp, foff, m); 4251 } else if (m->valid == VM_PAGE_BITS_ALL && 4252 (bp->b_flags & B_CACHE) == 0) { 4253 bp->b_pages[i] = bogus_page; 4254 bogus++; 4255 } 4256 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4257 } 4258 VM_OBJECT_WUNLOCK(obj); 4259 if (bogus && buf_mapped(bp)) { 4260 BUF_CHECK_MAPPED(bp); 4261 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4262 bp->b_pages, bp->b_npages); 4263 } 4264 } 4265 4266 /* 4267 * vfs_bio_set_valid: 4268 * 4269 * Set the range within the buffer to valid. The range is 4270 * relative to the beginning of the buffer, b_offset. Note that 4271 * b_offset itself may be offset from the beginning of the first 4272 * page. 4273 */ 4274 void 4275 vfs_bio_set_valid(struct buf *bp, int base, int size) 4276 { 4277 int i, n; 4278 vm_page_t m; 4279 4280 if (!(bp->b_flags & B_VMIO)) 4281 return; 4282 4283 /* 4284 * Fixup base to be relative to beginning of first page. 4285 * Set initial n to be the maximum number of bytes in the 4286 * first page that can be validated. 4287 */ 4288 base += (bp->b_offset & PAGE_MASK); 4289 n = PAGE_SIZE - (base & PAGE_MASK); 4290 4291 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4292 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4293 m = bp->b_pages[i]; 4294 if (n > size) 4295 n = size; 4296 vm_page_set_valid_range(m, base & PAGE_MASK, n); 4297 base += n; 4298 size -= n; 4299 n = PAGE_SIZE; 4300 } 4301 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4302 } 4303 4304 /* 4305 * vfs_bio_clrbuf: 4306 * 4307 * If the specified buffer is a non-VMIO buffer, clear the entire 4308 * buffer. If the specified buffer is a VMIO buffer, clear and 4309 * validate only the previously invalid portions of the buffer. 4310 * This routine essentially fakes an I/O, so we need to clear 4311 * BIO_ERROR and B_INVAL. 4312 * 4313 * Note that while we only theoretically need to clear through b_bcount, 4314 * we go ahead and clear through b_bufsize. 4315 */ 4316 void 4317 vfs_bio_clrbuf(struct buf *bp) 4318 { 4319 int i, j, mask, sa, ea, slide; 4320 4321 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 4322 clrbuf(bp); 4323 return; 4324 } 4325 bp->b_flags &= ~B_INVAL; 4326 bp->b_ioflags &= ~BIO_ERROR; 4327 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4328 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 4329 (bp->b_offset & PAGE_MASK) == 0) { 4330 if (bp->b_pages[0] == bogus_page) 4331 goto unlock; 4332 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 4333 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object); 4334 if ((bp->b_pages[0]->valid & mask) == mask) 4335 goto unlock; 4336 if ((bp->b_pages[0]->valid & mask) == 0) { 4337 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize); 4338 bp->b_pages[0]->valid |= mask; 4339 goto unlock; 4340 } 4341 } 4342 sa = bp->b_offset & PAGE_MASK; 4343 slide = 0; 4344 for (i = 0; i < bp->b_npages; i++, sa = 0) { 4345 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize); 4346 ea = slide & PAGE_MASK; 4347 if (ea == 0) 4348 ea = PAGE_SIZE; 4349 if (bp->b_pages[i] == bogus_page) 4350 continue; 4351 j = sa / DEV_BSIZE; 4352 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 4353 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object); 4354 if ((bp->b_pages[i]->valid & mask) == mask) 4355 continue; 4356 if ((bp->b_pages[i]->valid & mask) == 0) 4357 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa); 4358 else { 4359 for (; sa < ea; sa += DEV_BSIZE, j++) { 4360 if ((bp->b_pages[i]->valid & (1 << j)) == 0) { 4361 pmap_zero_page_area(bp->b_pages[i], 4362 sa, DEV_BSIZE); 4363 } 4364 } 4365 } 4366 bp->b_pages[i]->valid |= mask; 4367 } 4368 unlock: 4369 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4370 bp->b_resid = 0; 4371 } 4372 4373 void 4374 vfs_bio_bzero_buf(struct buf *bp, int base, int size) 4375 { 4376 vm_page_t m; 4377 int i, n; 4378 4379 if (buf_mapped(bp)) { 4380 BUF_CHECK_MAPPED(bp); 4381 bzero(bp->b_data + base, size); 4382 } else { 4383 BUF_CHECK_UNMAPPED(bp); 4384 n = PAGE_SIZE - (base & PAGE_MASK); 4385 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4386 m = bp->b_pages[i]; 4387 if (n > size) 4388 n = size; 4389 pmap_zero_page_area(m, base & PAGE_MASK, n); 4390 base += n; 4391 size -= n; 4392 n = PAGE_SIZE; 4393 } 4394 } 4395 } 4396 4397 /* 4398 * vm_hold_load_pages and vm_hold_free_pages get pages into 4399 * a buffers address space. The pages are anonymous and are 4400 * not associated with a file object. 4401 */ 4402 static void 4403 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4404 { 4405 vm_offset_t pg; 4406 vm_page_t p; 4407 int index; 4408 4409 BUF_CHECK_MAPPED(bp); 4410 4411 to = round_page(to); 4412 from = round_page(from); 4413 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4414 4415 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 4416 tryagain: 4417 /* 4418 * note: must allocate system pages since blocking here 4419 * could interfere with paging I/O, no matter which 4420 * process we are. 4421 */ 4422 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ | 4423 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT)); 4424 if (p == NULL) { 4425 VM_WAIT; 4426 goto tryagain; 4427 } 4428 pmap_qenter(pg, &p, 1); 4429 bp->b_pages[index] = p; 4430 } 4431 bp->b_npages = index; 4432 } 4433 4434 /* Return pages associated with this buf to the vm system */ 4435 static void 4436 vm_hold_free_pages(struct buf *bp, int newbsize) 4437 { 4438 vm_offset_t from; 4439 vm_page_t p; 4440 int index, newnpages; 4441 4442 BUF_CHECK_MAPPED(bp); 4443 4444 from = round_page((vm_offset_t)bp->b_data + newbsize); 4445 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4446 if (bp->b_npages > newnpages) 4447 pmap_qremove(from, bp->b_npages - newnpages); 4448 for (index = newnpages; index < bp->b_npages; index++) { 4449 p = bp->b_pages[index]; 4450 bp->b_pages[index] = NULL; 4451 if (vm_page_sbusied(p)) 4452 printf("vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 4453 (intmax_t)bp->b_blkno, (intmax_t)bp->b_lblkno); 4454 p->wire_count--; 4455 vm_page_free(p); 4456 atomic_subtract_int(&vm_cnt.v_wire_count, 1); 4457 } 4458 bp->b_npages = newnpages; 4459 } 4460 4461 /* 4462 * Map an IO request into kernel virtual address space. 4463 * 4464 * All requests are (re)mapped into kernel VA space. 4465 * Notice that we use b_bufsize for the size of the buffer 4466 * to be mapped. b_bcount might be modified by the driver. 4467 * 4468 * Note that even if the caller determines that the address space should 4469 * be valid, a race or a smaller-file mapped into a larger space may 4470 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 4471 * check the return value. 4472 * 4473 * This function only works with pager buffers. 4474 */ 4475 int 4476 vmapbuf(struct buf *bp, int mapbuf) 4477 { 4478 vm_prot_t prot; 4479 int pidx; 4480 4481 if (bp->b_bufsize < 0) 4482 return (-1); 4483 prot = VM_PROT_READ; 4484 if (bp->b_iocmd == BIO_READ) 4485 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 4486 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 4487 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages, 4488 btoc(MAXPHYS))) < 0) 4489 return (-1); 4490 bp->b_npages = pidx; 4491 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK; 4492 if (mapbuf || !unmapped_buf_allowed) { 4493 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_pages, pidx); 4494 bp->b_data = bp->b_kvabase + bp->b_offset; 4495 } else 4496 bp->b_data = unmapped_buf; 4497 return(0); 4498 } 4499 4500 /* 4501 * Free the io map PTEs associated with this IO operation. 4502 * We also invalidate the TLB entries and restore the original b_addr. 4503 * 4504 * This function only works with pager buffers. 4505 */ 4506 void 4507 vunmapbuf(struct buf *bp) 4508 { 4509 int npages; 4510 4511 npages = bp->b_npages; 4512 if (buf_mapped(bp)) 4513 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 4514 vm_page_unhold_pages(bp->b_pages, npages); 4515 4516 bp->b_data = unmapped_buf; 4517 } 4518 4519 void 4520 bdone(struct buf *bp) 4521 { 4522 struct mtx *mtxp; 4523 4524 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4525 mtx_lock(mtxp); 4526 bp->b_flags |= B_DONE; 4527 wakeup(bp); 4528 mtx_unlock(mtxp); 4529 } 4530 4531 void 4532 bwait(struct buf *bp, u_char pri, const char *wchan) 4533 { 4534 struct mtx *mtxp; 4535 4536 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4537 mtx_lock(mtxp); 4538 while ((bp->b_flags & B_DONE) == 0) 4539 msleep(bp, mtxp, pri, wchan, 0); 4540 mtx_unlock(mtxp); 4541 } 4542 4543 int 4544 bufsync(struct bufobj *bo, int waitfor) 4545 { 4546 4547 return (VOP_FSYNC(bo2vnode(bo), waitfor, curthread)); 4548 } 4549 4550 void 4551 bufstrategy(struct bufobj *bo, struct buf *bp) 4552 { 4553 int i = 0; 4554 struct vnode *vp; 4555 4556 vp = bp->b_vp; 4557 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 4558 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 4559 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 4560 i = VOP_STRATEGY(vp, bp); 4561 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 4562 } 4563 4564 void 4565 bufobj_wrefl(struct bufobj *bo) 4566 { 4567 4568 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4569 ASSERT_BO_WLOCKED(bo); 4570 bo->bo_numoutput++; 4571 } 4572 4573 void 4574 bufobj_wref(struct bufobj *bo) 4575 { 4576 4577 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4578 BO_LOCK(bo); 4579 bo->bo_numoutput++; 4580 BO_UNLOCK(bo); 4581 } 4582 4583 void 4584 bufobj_wdrop(struct bufobj *bo) 4585 { 4586 4587 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 4588 BO_LOCK(bo); 4589 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 4590 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 4591 bo->bo_flag &= ~BO_WWAIT; 4592 wakeup(&bo->bo_numoutput); 4593 } 4594 BO_UNLOCK(bo); 4595 } 4596 4597 int 4598 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 4599 { 4600 int error; 4601 4602 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 4603 ASSERT_BO_WLOCKED(bo); 4604 error = 0; 4605 while (bo->bo_numoutput) { 4606 bo->bo_flag |= BO_WWAIT; 4607 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo), 4608 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 4609 if (error) 4610 break; 4611 } 4612 return (error); 4613 } 4614 4615 /* 4616 * Set bio_data or bio_ma for struct bio from the struct buf. 4617 */ 4618 void 4619 bdata2bio(struct buf *bp, struct bio *bip) 4620 { 4621 4622 if (!buf_mapped(bp)) { 4623 KASSERT(unmapped_buf_allowed, ("unmapped")); 4624 bip->bio_ma = bp->b_pages; 4625 bip->bio_ma_n = bp->b_npages; 4626 bip->bio_data = unmapped_buf; 4627 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 4628 bip->bio_flags |= BIO_UNMAPPED; 4629 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) / 4630 PAGE_SIZE == bp->b_npages, 4631 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset, 4632 (long long)bip->bio_length, bip->bio_ma_n)); 4633 } else { 4634 bip->bio_data = bp->b_data; 4635 bip->bio_ma = NULL; 4636 } 4637 } 4638 4639 #include "opt_ddb.h" 4640 #ifdef DDB 4641 #include <ddb/ddb.h> 4642 4643 /* DDB command to show buffer data */ 4644 DB_SHOW_COMMAND(buffer, db_show_buffer) 4645 { 4646 /* get args */ 4647 struct buf *bp = (struct buf *)addr; 4648 4649 if (!have_addr) { 4650 db_printf("usage: show buffer <addr>\n"); 4651 return; 4652 } 4653 4654 db_printf("buf at %p\n", bp); 4655 db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n", 4656 (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags, 4657 PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS); 4658 db_printf( 4659 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 4660 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, " 4661 "b_dep = %p\n", 4662 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 4663 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 4664 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first); 4665 db_printf("b_kvabase = %p, b_kvasize = %d\n", 4666 bp->b_kvabase, bp->b_kvasize); 4667 if (bp->b_npages) { 4668 int i; 4669 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 4670 for (i = 0; i < bp->b_npages; i++) { 4671 vm_page_t m; 4672 m = bp->b_pages[i]; 4673 if (m != NULL) 4674 db_printf("(%p, 0x%lx, 0x%lx)", m->object, 4675 (u_long)m->pindex, 4676 (u_long)VM_PAGE_TO_PHYS(m)); 4677 else 4678 db_printf("( ??? )"); 4679 if ((i + 1) < bp->b_npages) 4680 db_printf(","); 4681 } 4682 db_printf("\n"); 4683 } 4684 db_printf(" "); 4685 BUF_LOCKPRINTINFO(bp); 4686 } 4687 4688 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 4689 { 4690 struct buf *bp; 4691 int i; 4692 4693 for (i = 0; i < nbuf; i++) { 4694 bp = &buf[i]; 4695 if (BUF_ISLOCKED(bp)) { 4696 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4697 db_printf("\n"); 4698 } 4699 } 4700 } 4701 4702 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 4703 { 4704 struct vnode *vp; 4705 struct buf *bp; 4706 4707 if (!have_addr) { 4708 db_printf("usage: show vnodebufs <addr>\n"); 4709 return; 4710 } 4711 vp = (struct vnode *)addr; 4712 db_printf("Clean buffers:\n"); 4713 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 4714 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4715 db_printf("\n"); 4716 } 4717 db_printf("Dirty buffers:\n"); 4718 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 4719 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4720 db_printf("\n"); 4721 } 4722 } 4723 4724 DB_COMMAND(countfreebufs, db_coundfreebufs) 4725 { 4726 struct buf *bp; 4727 int i, used = 0, nfree = 0; 4728 4729 if (have_addr) { 4730 db_printf("usage: countfreebufs\n"); 4731 return; 4732 } 4733 4734 for (i = 0; i < nbuf; i++) { 4735 bp = &buf[i]; 4736 if (bp->b_qindex == QUEUE_EMPTY) 4737 nfree++; 4738 else 4739 used++; 4740 } 4741 4742 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 4743 nfree + used); 4744 db_printf("numfreebuffers is %d\n", numfreebuffers); 4745 } 4746 #endif /* DDB */ 4747