1 /*- 2 * Copyright (c) 2004 Poul-Henning Kamp 3 * Copyright (c) 1994,1997 John S. Dyson 4 * Copyright (c) 2013 The FreeBSD Foundation 5 * All rights reserved. 6 * 7 * Portions of this software were developed by Konstantin Belousov 8 * under sponsorship from the FreeBSD Foundation. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 /* 33 * this file contains a new buffer I/O scheme implementing a coherent 34 * VM object and buffer cache scheme. Pains have been taken to make 35 * sure that the performance degradation associated with schemes such 36 * as this is not realized. 37 * 38 * Author: John S. Dyson 39 * Significant help during the development and debugging phases 40 * had been provided by David Greenman, also of the FreeBSD core team. 41 * 42 * see man buf(9) for more info. 43 */ 44 45 #include <sys/cdefs.h> 46 __FBSDID("$FreeBSD$"); 47 48 #include <sys/param.h> 49 #include <sys/systm.h> 50 #include <sys/bio.h> 51 #include <sys/conf.h> 52 #include <sys/buf.h> 53 #include <sys/devicestat.h> 54 #include <sys/eventhandler.h> 55 #include <sys/fail.h> 56 #include <sys/limits.h> 57 #include <sys/lock.h> 58 #include <sys/malloc.h> 59 #include <sys/mount.h> 60 #include <sys/mutex.h> 61 #include <sys/kernel.h> 62 #include <sys/kthread.h> 63 #include <sys/proc.h> 64 #include <sys/resourcevar.h> 65 #include <sys/rwlock.h> 66 #include <sys/smp.h> 67 #include <sys/sysctl.h> 68 #include <sys/sysproto.h> 69 #include <sys/vmem.h> 70 #include <sys/vmmeter.h> 71 #include <sys/vnode.h> 72 #include <sys/watchdog.h> 73 #include <geom/geom.h> 74 #include <vm/vm.h> 75 #include <vm/vm_param.h> 76 #include <vm/vm_kern.h> 77 #include <vm/vm_pageout.h> 78 #include <vm/vm_page.h> 79 #include <vm/vm_object.h> 80 #include <vm/vm_extern.h> 81 #include <vm/vm_map.h> 82 #include <vm/swap_pager.h> 83 #include "opt_compat.h" 84 #include "opt_swap.h" 85 86 static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer"); 87 88 struct bio_ops bioops; /* I/O operation notification */ 89 90 struct buf_ops buf_ops_bio = { 91 .bop_name = "buf_ops_bio", 92 .bop_write = bufwrite, 93 .bop_strategy = bufstrategy, 94 .bop_sync = bufsync, 95 .bop_bdflush = bufbdflush, 96 }; 97 98 static struct buf *buf; /* buffer header pool */ 99 extern struct buf *swbuf; /* Swap buffer header pool. */ 100 caddr_t unmapped_buf; 101 102 /* Used below and for softdep flushing threads in ufs/ffs/ffs_softdep.c */ 103 struct proc *bufdaemonproc; 104 struct proc *bufspacedaemonproc; 105 106 static int inmem(struct vnode *vp, daddr_t blkno); 107 static void vm_hold_free_pages(struct buf *bp, int newbsize); 108 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from, 109 vm_offset_t to); 110 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m); 111 static void vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, 112 vm_page_t m); 113 static void vfs_clean_pages_dirty_buf(struct buf *bp); 114 static void vfs_setdirty_locked_object(struct buf *bp); 115 static void vfs_vmio_invalidate(struct buf *bp); 116 static void vfs_vmio_truncate(struct buf *bp, int npages); 117 static void vfs_vmio_extend(struct buf *bp, int npages, int size); 118 static int vfs_bio_clcheck(struct vnode *vp, int size, 119 daddr_t lblkno, daddr_t blkno); 120 static int buf_flush(struct vnode *vp, int); 121 static int buf_recycle(bool); 122 static int buf_scan(bool); 123 static int flushbufqueues(struct vnode *, int, int); 124 static void buf_daemon(void); 125 static void bremfreel(struct buf *bp); 126 static __inline void bd_wakeup(void); 127 static int sysctl_runningspace(SYSCTL_HANDLER_ARGS); 128 static void bufkva_reclaim(vmem_t *, int); 129 static void bufkva_free(struct buf *); 130 static int buf_import(void *, void **, int, int); 131 static void buf_release(void *, void **, int); 132 133 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 134 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 135 static int sysctl_bufspace(SYSCTL_HANDLER_ARGS); 136 #endif 137 138 int vmiodirenable = TRUE; 139 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, 140 "Use the VM system for directory writes"); 141 long runningbufspace; 142 SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 143 "Amount of presently outstanding async buffer io"); 144 static long bufspace; 145 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 146 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 147 SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD, 148 &bufspace, 0, sysctl_bufspace, "L", "Virtual memory used for buffers"); 149 #else 150 SYSCTL_LONG(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, 151 "Physical memory used for buffers"); 152 #endif 153 static long bufkvaspace; 154 SYSCTL_LONG(_vfs, OID_AUTO, bufkvaspace, CTLFLAG_RD, &bufkvaspace, 0, 155 "Kernel virtual memory used for buffers"); 156 static long maxbufspace; 157 SYSCTL_LONG(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RW, &maxbufspace, 0, 158 "Maximum allowed value of bufspace (including metadata)"); 159 static long bufmallocspace; 160 SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 161 "Amount of malloced memory for buffers"); 162 static long maxbufmallocspace; 163 SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 164 0, "Maximum amount of malloced memory for buffers"); 165 static long lobufspace; 166 SYSCTL_LONG(_vfs, OID_AUTO, lobufspace, CTLFLAG_RW, &lobufspace, 0, 167 "Minimum amount of buffers we want to have"); 168 long hibufspace; 169 SYSCTL_LONG(_vfs, OID_AUTO, hibufspace, CTLFLAG_RW, &hibufspace, 0, 170 "Maximum allowed value of bufspace (excluding metadata)"); 171 long bufspacethresh; 172 SYSCTL_LONG(_vfs, OID_AUTO, bufspacethresh, CTLFLAG_RW, &bufspacethresh, 173 0, "Bufspace consumed before waking the daemon to free some"); 174 static int buffreekvacnt; 175 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0, 176 "Number of times we have freed the KVA space from some buffer"); 177 static int bufdefragcnt; 178 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0, 179 "Number of times we have had to repeat buffer allocation to defragment"); 180 static long lorunningspace; 181 SYSCTL_PROC(_vfs, OID_AUTO, lorunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE | 182 CTLFLAG_RW, &lorunningspace, 0, sysctl_runningspace, "L", 183 "Minimum preferred space used for in-progress I/O"); 184 static long hirunningspace; 185 SYSCTL_PROC(_vfs, OID_AUTO, hirunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE | 186 CTLFLAG_RW, &hirunningspace, 0, sysctl_runningspace, "L", 187 "Maximum amount of space to use for in-progress I/O"); 188 int dirtybufferflushes; 189 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes, 190 0, "Number of bdwrite to bawrite conversions to limit dirty buffers"); 191 int bdwriteskip; 192 SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip, 193 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk"); 194 int altbufferflushes; 195 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes, 196 0, "Number of fsync flushes to limit dirty buffers"); 197 static int recursiveflushes; 198 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes, 199 0, "Number of flushes skipped due to being recursive"); 200 static int numdirtybuffers; 201 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0, 202 "Number of buffers that are dirty (has unwritten changes) at the moment"); 203 static int lodirtybuffers; 204 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0, 205 "How many buffers we want to have free before bufdaemon can sleep"); 206 static int hidirtybuffers; 207 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0, 208 "When the number of dirty buffers is considered severe"); 209 int dirtybufthresh; 210 SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh, 211 0, "Number of bdwrite to bawrite conversions to clear dirty buffers"); 212 static int numfreebuffers; 213 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, 214 "Number of free buffers"); 215 static int lofreebuffers; 216 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0, 217 "Target number of free buffers"); 218 static int hifreebuffers; 219 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0, 220 "Threshold for clean buffer recycling"); 221 static int getnewbufcalls; 222 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0, 223 "Number of calls to getnewbuf"); 224 static int getnewbufrestarts; 225 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0, 226 "Number of times getnewbuf has had to restart a buffer aquisition"); 227 static int mappingrestarts; 228 SYSCTL_INT(_vfs, OID_AUTO, mappingrestarts, CTLFLAG_RW, &mappingrestarts, 0, 229 "Number of times getblk has had to restart a buffer mapping for " 230 "unmapped buffer"); 231 static int numbufallocfails; 232 SYSCTL_INT(_vfs, OID_AUTO, numbufallocfails, CTLFLAG_RW, &numbufallocfails, 0, 233 "Number of times buffer allocations failed"); 234 static int flushbufqtarget = 100; 235 SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0, 236 "Amount of work to do in flushbufqueues when helping bufdaemon"); 237 static long notbufdflushes; 238 SYSCTL_LONG(_vfs, OID_AUTO, notbufdflushes, CTLFLAG_RD, ¬bufdflushes, 0, 239 "Number of dirty buffer flushes done by the bufdaemon helpers"); 240 static long barrierwrites; 241 SYSCTL_LONG(_vfs, OID_AUTO, barrierwrites, CTLFLAG_RW, &barrierwrites, 0, 242 "Number of barrier writes"); 243 SYSCTL_INT(_vfs, OID_AUTO, unmapped_buf_allowed, CTLFLAG_RD, 244 &unmapped_buf_allowed, 0, 245 "Permit the use of the unmapped i/o"); 246 247 /* 248 * This lock synchronizes access to bd_request. 249 */ 250 static struct mtx_padalign bdlock; 251 252 /* 253 * This lock protects the runningbufreq and synchronizes runningbufwakeup and 254 * waitrunningbufspace(). 255 */ 256 static struct mtx_padalign rbreqlock; 257 258 /* 259 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it. 260 */ 261 static struct rwlock_padalign nblock; 262 263 /* 264 * Lock that protects bdirtywait. 265 */ 266 static struct mtx_padalign bdirtylock; 267 268 /* 269 * Wakeup point for bufdaemon, as well as indicator of whether it is already 270 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it 271 * is idling. 272 */ 273 static int bd_request; 274 275 /* 276 * Request/wakeup point for the bufspace daemon. 277 */ 278 static int bufspace_request; 279 280 /* 281 * Request for the buf daemon to write more buffers than is indicated by 282 * lodirtybuf. This may be necessary to push out excess dependencies or 283 * defragment the address space where a simple count of the number of dirty 284 * buffers is insufficient to characterize the demand for flushing them. 285 */ 286 static int bd_speedupreq; 287 288 /* 289 * bogus page -- for I/O to/from partially complete buffers 290 * this is a temporary solution to the problem, but it is not 291 * really that bad. it would be better to split the buffer 292 * for input in the case of buffers partially already in memory, 293 * but the code is intricate enough already. 294 */ 295 vm_page_t bogus_page; 296 297 /* 298 * Synchronization (sleep/wakeup) variable for active buffer space requests. 299 * Set when wait starts, cleared prior to wakeup(). 300 * Used in runningbufwakeup() and waitrunningbufspace(). 301 */ 302 static int runningbufreq; 303 304 /* 305 * Synchronization (sleep/wakeup) variable for buffer requests. 306 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done 307 * by and/or. 308 * Used in numdirtywakeup(), bufspace_wakeup(), bwillwrite(), 309 * getnewbuf(), and getblk(). 310 */ 311 static volatile int needsbuffer; 312 313 /* 314 * Synchronization for bwillwrite() waiters. 315 */ 316 static int bdirtywait; 317 318 /* 319 * Definitions for the buffer free lists. 320 */ 321 #define QUEUE_NONE 0 /* on no queue */ 322 #define QUEUE_EMPTY 1 /* empty buffer headers */ 323 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */ 324 #define QUEUE_CLEAN 3 /* non-B_DELWRI buffers */ 325 #define QUEUE_SENTINEL 1024 /* not an queue index, but mark for sentinel */ 326 327 /* Maximum number of clean buffer queues. */ 328 #define CLEAN_QUEUES 16 329 330 /* Configured number of clean queues. */ 331 static int clean_queues; 332 333 /* Maximum number of buffer queues. */ 334 #define BUFFER_QUEUES (QUEUE_CLEAN + CLEAN_QUEUES) 335 336 /* Queues for free buffers with various properties */ 337 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } }; 338 #ifdef INVARIANTS 339 static int bq_len[BUFFER_QUEUES]; 340 #endif 341 342 /* 343 * Lock for each bufqueue 344 */ 345 static struct mtx_padalign bqlocks[BUFFER_QUEUES]; 346 347 /* 348 * per-cpu empty buffer cache. 349 */ 350 uma_zone_t buf_zone; 351 352 /* 353 * Single global constant for BUF_WMESG, to avoid getting multiple references. 354 * buf_wmesg is referred from macros. 355 */ 356 const char *buf_wmesg = BUF_WMESG; 357 358 static int 359 sysctl_runningspace(SYSCTL_HANDLER_ARGS) 360 { 361 long value; 362 int error; 363 364 value = *(long *)arg1; 365 error = sysctl_handle_long(oidp, &value, 0, req); 366 if (error != 0 || req->newptr == NULL) 367 return (error); 368 mtx_lock(&rbreqlock); 369 if (arg1 == &hirunningspace) { 370 if (value < lorunningspace) 371 error = EINVAL; 372 else 373 hirunningspace = value; 374 } else { 375 KASSERT(arg1 == &lorunningspace, 376 ("%s: unknown arg1", __func__)); 377 if (value > hirunningspace) 378 error = EINVAL; 379 else 380 lorunningspace = value; 381 } 382 mtx_unlock(&rbreqlock); 383 return (error); 384 } 385 386 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 387 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 388 static int 389 sysctl_bufspace(SYSCTL_HANDLER_ARGS) 390 { 391 long lvalue; 392 int ivalue; 393 394 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long)) 395 return (sysctl_handle_long(oidp, arg1, arg2, req)); 396 lvalue = *(long *)arg1; 397 if (lvalue > INT_MAX) 398 /* On overflow, still write out a long to trigger ENOMEM. */ 399 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 400 ivalue = lvalue; 401 return (sysctl_handle_int(oidp, &ivalue, 0, req)); 402 } 403 #endif 404 405 static int 406 bqcleanq(void) 407 { 408 static int nextq; 409 410 return ((atomic_fetchadd_int(&nextq, 1) % clean_queues) + QUEUE_CLEAN); 411 } 412 413 static int 414 bqisclean(int qindex) 415 { 416 417 return (qindex >= QUEUE_CLEAN && qindex < QUEUE_CLEAN + CLEAN_QUEUES); 418 } 419 420 /* 421 * bqlock: 422 * 423 * Return the appropriate queue lock based on the index. 424 */ 425 static inline struct mtx * 426 bqlock(int qindex) 427 { 428 429 return (struct mtx *)&bqlocks[qindex]; 430 } 431 432 /* 433 * bdirtywakeup: 434 * 435 * Wakeup any bwillwrite() waiters. 436 */ 437 static void 438 bdirtywakeup(void) 439 { 440 mtx_lock(&bdirtylock); 441 if (bdirtywait) { 442 bdirtywait = 0; 443 wakeup(&bdirtywait); 444 } 445 mtx_unlock(&bdirtylock); 446 } 447 448 /* 449 * bdirtysub: 450 * 451 * Decrement the numdirtybuffers count by one and wakeup any 452 * threads blocked in bwillwrite(). 453 */ 454 static void 455 bdirtysub(void) 456 { 457 458 if (atomic_fetchadd_int(&numdirtybuffers, -1) == 459 (lodirtybuffers + hidirtybuffers) / 2) 460 bdirtywakeup(); 461 } 462 463 /* 464 * bdirtyadd: 465 * 466 * Increment the numdirtybuffers count by one and wakeup the buf 467 * daemon if needed. 468 */ 469 static void 470 bdirtyadd(void) 471 { 472 473 /* 474 * Only do the wakeup once as we cross the boundary. The 475 * buf daemon will keep running until the condition clears. 476 */ 477 if (atomic_fetchadd_int(&numdirtybuffers, 1) == 478 (lodirtybuffers + hidirtybuffers) / 2) 479 bd_wakeup(); 480 } 481 482 /* 483 * bufspace_wakeup: 484 * 485 * Called when buffer space is potentially available for recovery. 486 * getnewbuf() will block on this flag when it is unable to free 487 * sufficient buffer space. Buffer space becomes recoverable when 488 * bp's get placed back in the queues. 489 */ 490 static void 491 bufspace_wakeup(void) 492 { 493 494 /* 495 * If someone is waiting for bufspace, wake them up. 496 * 497 * Since needsbuffer is set prior to doing an additional queue 498 * scan it is safe to check for the flag prior to acquiring the 499 * lock. The thread that is preparing to scan again before 500 * blocking would discover the buf we released. 501 */ 502 if (needsbuffer) { 503 rw_rlock(&nblock); 504 if (atomic_cmpset_int(&needsbuffer, 1, 0) == 1) 505 wakeup(__DEVOLATILE(void *, &needsbuffer)); 506 rw_runlock(&nblock); 507 } 508 } 509 510 /* 511 * bufspace_daemonwakeup: 512 * 513 * Wakeup the daemon responsible for freeing clean bufs. 514 */ 515 static void 516 bufspace_daemonwakeup(void) 517 { 518 rw_rlock(&nblock); 519 if (bufspace_request == 0) { 520 bufspace_request = 1; 521 wakeup(&bufspace_request); 522 } 523 rw_runlock(&nblock); 524 } 525 526 /* 527 * bufspace_adjust: 528 * 529 * Adjust the reported bufspace for a KVA managed buffer, possibly 530 * waking any waiters. 531 */ 532 static void 533 bufspace_adjust(struct buf *bp, int bufsize) 534 { 535 long space; 536 int diff; 537 538 KASSERT((bp->b_flags & B_MALLOC) == 0, 539 ("bufspace_adjust: malloc buf %p", bp)); 540 diff = bufsize - bp->b_bufsize; 541 if (diff < 0) { 542 atomic_subtract_long(&bufspace, -diff); 543 bufspace_wakeup(); 544 } else { 545 space = atomic_fetchadd_long(&bufspace, diff); 546 /* Wake up the daemon on the transition. */ 547 if (space < bufspacethresh && space + diff >= bufspacethresh) 548 bufspace_daemonwakeup(); 549 } 550 bp->b_bufsize = bufsize; 551 } 552 553 /* 554 * bufspace_reserve: 555 * 556 * Reserve bufspace before calling allocbuf(). metadata has a 557 * different space limit than data. 558 */ 559 static int 560 bufspace_reserve(int size, bool metadata) 561 { 562 long limit; 563 long space; 564 565 if (metadata) 566 limit = maxbufspace; 567 else 568 limit = hibufspace; 569 do { 570 space = bufspace; 571 if (space + size > limit) 572 return (ENOSPC); 573 } while (atomic_cmpset_long(&bufspace, space, space + size) == 0); 574 575 /* Wake up the daemon on the transition. */ 576 if (space < bufspacethresh && space + size >= bufspacethresh) 577 bufspace_daemonwakeup(); 578 579 return (0); 580 } 581 582 /* 583 * bufspace_release: 584 * 585 * Release reserved bufspace after bufspace_adjust() has consumed it. 586 */ 587 static void 588 bufspace_release(int size) 589 { 590 atomic_subtract_long(&bufspace, size); 591 bufspace_wakeup(); 592 } 593 594 /* 595 * bufspace_wait: 596 * 597 * Wait for bufspace, acting as the buf daemon if a locked vnode is 598 * supplied. needsbuffer must be set in a safe fashion prior to 599 * polling for space. The operation must be re-tried on return. 600 */ 601 static void 602 bufspace_wait(struct vnode *vp, int gbflags, int slpflag, int slptimeo) 603 { 604 struct thread *td; 605 int error, fl, norunbuf; 606 607 if ((gbflags & GB_NOWAIT_BD) != 0) 608 return; 609 610 td = curthread; 611 rw_wlock(&nblock); 612 while (needsbuffer != 0) { 613 if (vp != NULL && vp->v_type != VCHR && 614 (td->td_pflags & TDP_BUFNEED) == 0) { 615 rw_wunlock(&nblock); 616 /* 617 * getblk() is called with a vnode locked, and 618 * some majority of the dirty buffers may as 619 * well belong to the vnode. Flushing the 620 * buffers there would make a progress that 621 * cannot be achieved by the buf_daemon, that 622 * cannot lock the vnode. 623 */ 624 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) | 625 (td->td_pflags & TDP_NORUNNINGBUF); 626 627 /* 628 * Play bufdaemon. The getnewbuf() function 629 * may be called while the thread owns lock 630 * for another dirty buffer for the same 631 * vnode, which makes it impossible to use 632 * VOP_FSYNC() there, due to the buffer lock 633 * recursion. 634 */ 635 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF; 636 fl = buf_flush(vp, flushbufqtarget); 637 td->td_pflags &= norunbuf; 638 rw_wlock(&nblock); 639 if (fl != 0) 640 continue; 641 if (needsbuffer == 0) 642 break; 643 } 644 error = rw_sleep(__DEVOLATILE(void *, &needsbuffer), &nblock, 645 (PRIBIO + 4) | slpflag, "newbuf", slptimeo); 646 if (error != 0) 647 break; 648 } 649 rw_wunlock(&nblock); 650 } 651 652 653 /* 654 * bufspace_daemon: 655 * 656 * buffer space management daemon. Tries to maintain some marginal 657 * amount of free buffer space so that requesting processes neither 658 * block nor work to reclaim buffers. 659 */ 660 static void 661 bufspace_daemon(void) 662 { 663 for (;;) { 664 kproc_suspend_check(bufspacedaemonproc); 665 666 /* 667 * Free buffers from the clean queue until we meet our 668 * targets. 669 * 670 * Theory of operation: The buffer cache is most efficient 671 * when some free buffer headers and space are always 672 * available to getnewbuf(). This daemon attempts to prevent 673 * the excessive blocking and synchronization associated 674 * with shortfall. It goes through three phases according 675 * demand: 676 * 677 * 1) The daemon wakes up voluntarily once per-second 678 * during idle periods when the counters are below 679 * the wakeup thresholds (bufspacethresh, lofreebuffers). 680 * 681 * 2) The daemon wakes up as we cross the thresholds 682 * ahead of any potential blocking. This may bounce 683 * slightly according to the rate of consumption and 684 * release. 685 * 686 * 3) The daemon and consumers are starved for working 687 * clean buffers. This is the 'bufspace' sleep below 688 * which will inefficiently trade bufs with bqrelse 689 * until we return to condition 2. 690 */ 691 while (bufspace > lobufspace || 692 numfreebuffers < hifreebuffers) { 693 if (buf_recycle(false) != 0) { 694 atomic_set_int(&needsbuffer, 1); 695 if (buf_recycle(false) != 0) { 696 rw_wlock(&nblock); 697 if (needsbuffer) 698 rw_sleep(__DEVOLATILE(void *, 699 &needsbuffer), &nblock, 700 PRIBIO|PDROP, "bufspace", 701 hz/10); 702 else 703 rw_wunlock(&nblock); 704 } 705 } 706 maybe_yield(); 707 } 708 709 /* 710 * Re-check our limits under the exclusive nblock. 711 */ 712 rw_wlock(&nblock); 713 if (bufspace < bufspacethresh && 714 numfreebuffers > lofreebuffers) { 715 bufspace_request = 0; 716 rw_sleep(&bufspace_request, &nblock, PRIBIO|PDROP, 717 "-", hz); 718 } else 719 rw_wunlock(&nblock); 720 } 721 } 722 723 static struct kproc_desc bufspace_kp = { 724 "bufspacedaemon", 725 bufspace_daemon, 726 &bufspacedaemonproc 727 }; 728 SYSINIT(bufspacedaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, 729 &bufspace_kp); 730 731 /* 732 * bufmallocadjust: 733 * 734 * Adjust the reported bufspace for a malloc managed buffer, possibly 735 * waking any waiters. 736 */ 737 static void 738 bufmallocadjust(struct buf *bp, int bufsize) 739 { 740 int diff; 741 742 KASSERT((bp->b_flags & B_MALLOC) != 0, 743 ("bufmallocadjust: non-malloc buf %p", bp)); 744 diff = bufsize - bp->b_bufsize; 745 if (diff < 0) 746 atomic_subtract_long(&bufmallocspace, -diff); 747 else 748 atomic_add_long(&bufmallocspace, diff); 749 bp->b_bufsize = bufsize; 750 } 751 752 /* 753 * runningwakeup: 754 * 755 * Wake up processes that are waiting on asynchronous writes to fall 756 * below lorunningspace. 757 */ 758 static void 759 runningwakeup(void) 760 { 761 762 mtx_lock(&rbreqlock); 763 if (runningbufreq) { 764 runningbufreq = 0; 765 wakeup(&runningbufreq); 766 } 767 mtx_unlock(&rbreqlock); 768 } 769 770 /* 771 * runningbufwakeup: 772 * 773 * Decrement the outstanding write count according. 774 */ 775 void 776 runningbufwakeup(struct buf *bp) 777 { 778 long space, bspace; 779 780 bspace = bp->b_runningbufspace; 781 if (bspace == 0) 782 return; 783 space = atomic_fetchadd_long(&runningbufspace, -bspace); 784 KASSERT(space >= bspace, ("runningbufspace underflow %ld %ld", 785 space, bspace)); 786 bp->b_runningbufspace = 0; 787 /* 788 * Only acquire the lock and wakeup on the transition from exceeding 789 * the threshold to falling below it. 790 */ 791 if (space < lorunningspace) 792 return; 793 if (space - bspace > lorunningspace) 794 return; 795 runningwakeup(); 796 } 797 798 /* 799 * waitrunningbufspace() 800 * 801 * runningbufspace is a measure of the amount of I/O currently 802 * running. This routine is used in async-write situations to 803 * prevent creating huge backups of pending writes to a device. 804 * Only asynchronous writes are governed by this function. 805 * 806 * This does NOT turn an async write into a sync write. It waits 807 * for earlier writes to complete and generally returns before the 808 * caller's write has reached the device. 809 */ 810 void 811 waitrunningbufspace(void) 812 { 813 814 mtx_lock(&rbreqlock); 815 while (runningbufspace > hirunningspace) { 816 runningbufreq = 1; 817 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 818 } 819 mtx_unlock(&rbreqlock); 820 } 821 822 823 /* 824 * vfs_buf_test_cache: 825 * 826 * Called when a buffer is extended. This function clears the B_CACHE 827 * bit if the newly extended portion of the buffer does not contain 828 * valid data. 829 */ 830 static __inline void 831 vfs_buf_test_cache(struct buf *bp, vm_ooffset_t foff, vm_offset_t off, 832 vm_offset_t size, vm_page_t m) 833 { 834 835 VM_OBJECT_ASSERT_LOCKED(m->object); 836 if (bp->b_flags & B_CACHE) { 837 int base = (foff + off) & PAGE_MASK; 838 if (vm_page_is_valid(m, base, size) == 0) 839 bp->b_flags &= ~B_CACHE; 840 } 841 } 842 843 /* Wake up the buffer daemon if necessary */ 844 static __inline void 845 bd_wakeup(void) 846 { 847 848 mtx_lock(&bdlock); 849 if (bd_request == 0) { 850 bd_request = 1; 851 wakeup(&bd_request); 852 } 853 mtx_unlock(&bdlock); 854 } 855 856 /* 857 * bd_speedup - speedup the buffer cache flushing code 858 */ 859 void 860 bd_speedup(void) 861 { 862 int needwake; 863 864 mtx_lock(&bdlock); 865 needwake = 0; 866 if (bd_speedupreq == 0 || bd_request == 0) 867 needwake = 1; 868 bd_speedupreq = 1; 869 bd_request = 1; 870 if (needwake) 871 wakeup(&bd_request); 872 mtx_unlock(&bdlock); 873 } 874 875 #ifndef NSWBUF_MIN 876 #define NSWBUF_MIN 16 877 #endif 878 879 #ifdef __i386__ 880 #define TRANSIENT_DENOM 5 881 #else 882 #define TRANSIENT_DENOM 10 883 #endif 884 885 /* 886 * Calculating buffer cache scaling values and reserve space for buffer 887 * headers. This is called during low level kernel initialization and 888 * may be called more then once. We CANNOT write to the memory area 889 * being reserved at this time. 890 */ 891 caddr_t 892 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 893 { 894 int tuned_nbuf; 895 long maxbuf, maxbuf_sz, buf_sz, biotmap_sz; 896 897 /* 898 * physmem_est is in pages. Convert it to kilobytes (assumes 899 * PAGE_SIZE is >= 1K) 900 */ 901 physmem_est = physmem_est * (PAGE_SIZE / 1024); 902 903 /* 904 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 905 * For the first 64MB of ram nominally allocate sufficient buffers to 906 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 907 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing 908 * the buffer cache we limit the eventual kva reservation to 909 * maxbcache bytes. 910 * 911 * factor represents the 1/4 x ram conversion. 912 */ 913 if (nbuf == 0) { 914 int factor = 4 * BKVASIZE / 1024; 915 916 nbuf = 50; 917 if (physmem_est > 4096) 918 nbuf += min((physmem_est - 4096) / factor, 919 65536 / factor); 920 if (physmem_est > 65536) 921 nbuf += min((physmem_est - 65536) * 2 / (factor * 5), 922 32 * 1024 * 1024 / (factor * 5)); 923 924 if (maxbcache && nbuf > maxbcache / BKVASIZE) 925 nbuf = maxbcache / BKVASIZE; 926 tuned_nbuf = 1; 927 } else 928 tuned_nbuf = 0; 929 930 /* XXX Avoid unsigned long overflows later on with maxbufspace. */ 931 maxbuf = (LONG_MAX / 3) / BKVASIZE; 932 if (nbuf > maxbuf) { 933 if (!tuned_nbuf) 934 printf("Warning: nbufs lowered from %d to %ld\n", nbuf, 935 maxbuf); 936 nbuf = maxbuf; 937 } 938 939 /* 940 * Ideal allocation size for the transient bio submap is 10% 941 * of the maximal space buffer map. This roughly corresponds 942 * to the amount of the buffer mapped for typical UFS load. 943 * 944 * Clip the buffer map to reserve space for the transient 945 * BIOs, if its extent is bigger than 90% (80% on i386) of the 946 * maximum buffer map extent on the platform. 947 * 948 * The fall-back to the maxbuf in case of maxbcache unset, 949 * allows to not trim the buffer KVA for the architectures 950 * with ample KVA space. 951 */ 952 if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) { 953 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE; 954 buf_sz = (long)nbuf * BKVASIZE; 955 if (buf_sz < maxbuf_sz / TRANSIENT_DENOM * 956 (TRANSIENT_DENOM - 1)) { 957 /* 958 * There is more KVA than memory. Do not 959 * adjust buffer map size, and assign the rest 960 * of maxbuf to transient map. 961 */ 962 biotmap_sz = maxbuf_sz - buf_sz; 963 } else { 964 /* 965 * Buffer map spans all KVA we could afford on 966 * this platform. Give 10% (20% on i386) of 967 * the buffer map to the transient bio map. 968 */ 969 biotmap_sz = buf_sz / TRANSIENT_DENOM; 970 buf_sz -= biotmap_sz; 971 } 972 if (biotmap_sz / INT_MAX > MAXPHYS) 973 bio_transient_maxcnt = INT_MAX; 974 else 975 bio_transient_maxcnt = biotmap_sz / MAXPHYS; 976 /* 977 * Artifically limit to 1024 simultaneous in-flight I/Os 978 * using the transient mapping. 979 */ 980 if (bio_transient_maxcnt > 1024) 981 bio_transient_maxcnt = 1024; 982 if (tuned_nbuf) 983 nbuf = buf_sz / BKVASIZE; 984 } 985 986 /* 987 * swbufs are used as temporary holders for I/O, such as paging I/O. 988 * We have no less then 16 and no more then 256. 989 */ 990 nswbuf = min(nbuf / 4, 256); 991 TUNABLE_INT_FETCH("kern.nswbuf", &nswbuf); 992 if (nswbuf < NSWBUF_MIN) 993 nswbuf = NSWBUF_MIN; 994 995 /* 996 * Reserve space for the buffer cache buffers 997 */ 998 swbuf = (void *)v; 999 v = (caddr_t)(swbuf + nswbuf); 1000 buf = (void *)v; 1001 v = (caddr_t)(buf + nbuf); 1002 1003 return(v); 1004 } 1005 1006 /* Initialize the buffer subsystem. Called before use of any buffers. */ 1007 void 1008 bufinit(void) 1009 { 1010 struct buf *bp; 1011 int i; 1012 1013 CTASSERT(MAXBCACHEBUF >= MAXBSIZE); 1014 mtx_init(&bqlocks[QUEUE_DIRTY], "bufq dirty lock", NULL, MTX_DEF); 1015 mtx_init(&bqlocks[QUEUE_EMPTY], "bufq empty lock", NULL, MTX_DEF); 1016 for (i = QUEUE_CLEAN; i < QUEUE_CLEAN + CLEAN_QUEUES; i++) 1017 mtx_init(&bqlocks[i], "bufq clean lock", NULL, MTX_DEF); 1018 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 1019 rw_init(&nblock, "needsbuffer lock"); 1020 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 1021 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF); 1022 1023 /* next, make a null set of free lists */ 1024 for (i = 0; i < BUFFER_QUEUES; i++) 1025 TAILQ_INIT(&bufqueues[i]); 1026 1027 unmapped_buf = (caddr_t)kva_alloc(MAXPHYS); 1028 1029 /* finally, initialize each buffer header and stick on empty q */ 1030 for (i = 0; i < nbuf; i++) { 1031 bp = &buf[i]; 1032 bzero(bp, sizeof *bp); 1033 bp->b_flags = B_INVAL; 1034 bp->b_rcred = NOCRED; 1035 bp->b_wcred = NOCRED; 1036 bp->b_qindex = QUEUE_EMPTY; 1037 bp->b_xflags = 0; 1038 bp->b_data = bp->b_kvabase = unmapped_buf; 1039 LIST_INIT(&bp->b_dep); 1040 BUF_LOCKINIT(bp); 1041 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 1042 #ifdef INVARIANTS 1043 bq_len[QUEUE_EMPTY]++; 1044 #endif 1045 } 1046 1047 /* 1048 * maxbufspace is the absolute maximum amount of buffer space we are 1049 * allowed to reserve in KVM and in real terms. The absolute maximum 1050 * is nominally used by metadata. hibufspace is the nominal maximum 1051 * used by most other requests. The differential is required to 1052 * ensure that metadata deadlocks don't occur. 1053 * 1054 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 1055 * this may result in KVM fragmentation which is not handled optimally 1056 * by the system. XXX This is less true with vmem. We could use 1057 * PAGE_SIZE. 1058 */ 1059 maxbufspace = (long)nbuf * BKVASIZE; 1060 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - MAXBCACHEBUF * 10); 1061 lobufspace = (hibufspace / 20) * 19; /* 95% */ 1062 bufspacethresh = lobufspace + (hibufspace - lobufspace) / 2; 1063 1064 /* 1065 * Note: The 16 MiB upper limit for hirunningspace was chosen 1066 * arbitrarily and may need further tuning. It corresponds to 1067 * 128 outstanding write IO requests (if IO size is 128 KiB), 1068 * which fits with many RAID controllers' tagged queuing limits. 1069 * The lower 1 MiB limit is the historical upper limit for 1070 * hirunningspace. 1071 */ 1072 hirunningspace = lmax(lmin(roundup(hibufspace / 64, MAXBCACHEBUF), 1073 16 * 1024 * 1024), 1024 * 1024); 1074 lorunningspace = roundup((hirunningspace * 2) / 3, MAXBCACHEBUF); 1075 1076 /* 1077 * Limit the amount of malloc memory since it is wired permanently into 1078 * the kernel space. Even though this is accounted for in the buffer 1079 * allocation, we don't want the malloced region to grow uncontrolled. 1080 * The malloc scheme improves memory utilization significantly on 1081 * average (small) directories. 1082 */ 1083 maxbufmallocspace = hibufspace / 20; 1084 1085 /* 1086 * Reduce the chance of a deadlock occuring by limiting the number 1087 * of delayed-write dirty buffers we allow to stack up. 1088 */ 1089 hidirtybuffers = nbuf / 4 + 20; 1090 dirtybufthresh = hidirtybuffers * 9 / 10; 1091 numdirtybuffers = 0; 1092 /* 1093 * To support extreme low-memory systems, make sure hidirtybuffers 1094 * cannot eat up all available buffer space. This occurs when our 1095 * minimum cannot be met. We try to size hidirtybuffers to 3/4 our 1096 * buffer space assuming BKVASIZE'd buffers. 1097 */ 1098 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 1099 hidirtybuffers >>= 1; 1100 } 1101 lodirtybuffers = hidirtybuffers / 2; 1102 1103 /* 1104 * lofreebuffers should be sufficient to avoid stalling waiting on 1105 * buf headers under heavy utilization. The bufs in per-cpu caches 1106 * are counted as free but will be unavailable to threads executing 1107 * on other cpus. 1108 * 1109 * hifreebuffers is the free target for the bufspace daemon. This 1110 * should be set appropriately to limit work per-iteration. 1111 */ 1112 lofreebuffers = MIN((nbuf / 25) + (20 * mp_ncpus), 128 * mp_ncpus); 1113 hifreebuffers = (3 * lofreebuffers) / 2; 1114 numfreebuffers = nbuf; 1115 1116 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ | 1117 VM_ALLOC_NORMAL | VM_ALLOC_WIRED); 1118 1119 /* Setup the kva and free list allocators. */ 1120 vmem_set_reclaim(buffer_arena, bufkva_reclaim); 1121 buf_zone = uma_zcache_create("buf free cache", sizeof(struct buf), 1122 NULL, NULL, NULL, NULL, buf_import, buf_release, NULL, 0); 1123 1124 /* 1125 * Size the clean queue according to the amount of buffer space. 1126 * One queue per-256mb up to the max. More queues gives better 1127 * concurrency but less accurate LRU. 1128 */ 1129 clean_queues = MIN(howmany(maxbufspace, 256*1024*1024), CLEAN_QUEUES); 1130 1131 } 1132 1133 #ifdef INVARIANTS 1134 static inline void 1135 vfs_buf_check_mapped(struct buf *bp) 1136 { 1137 1138 KASSERT(bp->b_kvabase != unmapped_buf, 1139 ("mapped buf: b_kvabase was not updated %p", bp)); 1140 KASSERT(bp->b_data != unmapped_buf, 1141 ("mapped buf: b_data was not updated %p", bp)); 1142 KASSERT(bp->b_data < unmapped_buf || bp->b_data >= unmapped_buf + 1143 MAXPHYS, ("b_data + b_offset unmapped %p", bp)); 1144 } 1145 1146 static inline void 1147 vfs_buf_check_unmapped(struct buf *bp) 1148 { 1149 1150 KASSERT(bp->b_data == unmapped_buf, 1151 ("unmapped buf: corrupted b_data %p", bp)); 1152 } 1153 1154 #define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp) 1155 #define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp) 1156 #else 1157 #define BUF_CHECK_MAPPED(bp) do {} while (0) 1158 #define BUF_CHECK_UNMAPPED(bp) do {} while (0) 1159 #endif 1160 1161 static int 1162 isbufbusy(struct buf *bp) 1163 { 1164 if (((bp->b_flags & (B_INVAL | B_PERSISTENT)) == 0 && 1165 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_pin_count = 0; 1483 bp->b_data = bp->b_kvabase = unmapped_buf; 1484 bp->b_fsprivate1 = NULL; 1485 bp->b_fsprivate2 = NULL; 1486 bp->b_fsprivate3 = NULL; 1487 LIST_INIT(&bp->b_dep); 1488 1489 return (bp); 1490 } 1491 1492 /* 1493 * buf_qrecycle: 1494 * 1495 * Free a buffer from the given bufqueue. kva controls whether the 1496 * freed buf must own some kva resources. This is used for 1497 * defragmenting. 1498 */ 1499 static int 1500 buf_qrecycle(int qindex, bool kva) 1501 { 1502 struct buf *bp, *nbp; 1503 1504 if (kva) 1505 atomic_add_int(&bufdefragcnt, 1); 1506 nbp = NULL; 1507 mtx_lock(&bqlocks[qindex]); 1508 nbp = TAILQ_FIRST(&bufqueues[qindex]); 1509 1510 /* 1511 * Run scan, possibly freeing data and/or kva mappings on the fly 1512 * depending. 1513 */ 1514 while ((bp = nbp) != NULL) { 1515 /* 1516 * Calculate next bp (we can only use it if we do not 1517 * release the bqlock). 1518 */ 1519 nbp = TAILQ_NEXT(bp, b_freelist); 1520 1521 /* 1522 * If we are defragging then we need a buffer with 1523 * some kva to reclaim. 1524 */ 1525 if (kva && bp->b_kvasize == 0) 1526 continue; 1527 1528 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1529 continue; 1530 1531 /* 1532 * Skip buffers with background writes in progress. 1533 */ 1534 if ((bp->b_vflags & BV_BKGRDINPROG) != 0) { 1535 BUF_UNLOCK(bp); 1536 continue; 1537 } 1538 1539 KASSERT(bp->b_qindex == qindex, 1540 ("getnewbuf: inconsistent queue %d bp %p", qindex, bp)); 1541 /* 1542 * NOTE: nbp is now entirely invalid. We can only restart 1543 * the scan from this point on. 1544 */ 1545 bremfreel(bp); 1546 mtx_unlock(&bqlocks[qindex]); 1547 1548 /* 1549 * Requeue the background write buffer with error and 1550 * restart the scan. 1551 */ 1552 if ((bp->b_vflags & BV_BKGRDERR) != 0) { 1553 bqrelse(bp); 1554 mtx_lock(&bqlocks[qindex]); 1555 nbp = TAILQ_FIRST(&bufqueues[qindex]); 1556 continue; 1557 } 1558 bp->b_flags |= B_INVAL; 1559 brelse(bp); 1560 return (0); 1561 } 1562 mtx_unlock(&bqlocks[qindex]); 1563 1564 return (ENOBUFS); 1565 } 1566 1567 /* 1568 * buf_recycle: 1569 * 1570 * Iterate through all clean queues until we find a buf to recycle or 1571 * exhaust the search. 1572 */ 1573 static int 1574 buf_recycle(bool kva) 1575 { 1576 int qindex, first_qindex; 1577 1578 qindex = first_qindex = bqcleanq(); 1579 do { 1580 if (buf_qrecycle(qindex, kva) == 0) 1581 return (0); 1582 if (++qindex == QUEUE_CLEAN + clean_queues) 1583 qindex = QUEUE_CLEAN; 1584 } while (qindex != first_qindex); 1585 1586 return (ENOBUFS); 1587 } 1588 1589 /* 1590 * buf_scan: 1591 * 1592 * Scan the clean queues looking for a buffer to recycle. needsbuffer 1593 * is set on failure so that the caller may optionally bufspace_wait() 1594 * in a race-free fashion. 1595 */ 1596 static int 1597 buf_scan(bool defrag) 1598 { 1599 int error; 1600 1601 /* 1602 * To avoid heavy synchronization and wakeup races we set 1603 * needsbuffer and re-poll before failing. This ensures that 1604 * no frees can be missed between an unsuccessful poll and 1605 * going to sleep in a synchronized fashion. 1606 */ 1607 if ((error = buf_recycle(defrag)) != 0) { 1608 atomic_set_int(&needsbuffer, 1); 1609 bufspace_daemonwakeup(); 1610 error = buf_recycle(defrag); 1611 } 1612 if (error == 0) 1613 atomic_add_int(&getnewbufrestarts, 1); 1614 return (error); 1615 } 1616 1617 /* 1618 * bremfree: 1619 * 1620 * Mark the buffer for removal from the appropriate free list. 1621 * 1622 */ 1623 void 1624 bremfree(struct buf *bp) 1625 { 1626 1627 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1628 KASSERT((bp->b_flags & B_REMFREE) == 0, 1629 ("bremfree: buffer %p already marked for delayed removal.", bp)); 1630 KASSERT(bp->b_qindex != QUEUE_NONE, 1631 ("bremfree: buffer %p not on a queue.", bp)); 1632 BUF_ASSERT_XLOCKED(bp); 1633 1634 bp->b_flags |= B_REMFREE; 1635 } 1636 1637 /* 1638 * bremfreef: 1639 * 1640 * Force an immediate removal from a free list. Used only in nfs when 1641 * it abuses the b_freelist pointer. 1642 */ 1643 void 1644 bremfreef(struct buf *bp) 1645 { 1646 struct mtx *qlock; 1647 1648 qlock = bqlock(bp->b_qindex); 1649 mtx_lock(qlock); 1650 bremfreel(bp); 1651 mtx_unlock(qlock); 1652 } 1653 1654 /* 1655 * bremfreel: 1656 * 1657 * Removes a buffer from the free list, must be called with the 1658 * correct qlock held. 1659 */ 1660 static void 1661 bremfreel(struct buf *bp) 1662 { 1663 1664 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X", 1665 bp, bp->b_vp, bp->b_flags); 1666 KASSERT(bp->b_qindex != QUEUE_NONE, 1667 ("bremfreel: buffer %p not on a queue.", bp)); 1668 if (bp->b_qindex != QUEUE_EMPTY) { 1669 BUF_ASSERT_XLOCKED(bp); 1670 } 1671 mtx_assert(bqlock(bp->b_qindex), MA_OWNED); 1672 1673 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 1674 #ifdef INVARIANTS 1675 KASSERT(bq_len[bp->b_qindex] >= 1, ("queue %d underflow", 1676 bp->b_qindex)); 1677 bq_len[bp->b_qindex]--; 1678 #endif 1679 bp->b_qindex = QUEUE_NONE; 1680 bp->b_flags &= ~B_REMFREE; 1681 } 1682 1683 /* 1684 * bufkva_free: 1685 * 1686 * Free the kva allocation for a buffer. 1687 * 1688 */ 1689 static void 1690 bufkva_free(struct buf *bp) 1691 { 1692 1693 #ifdef INVARIANTS 1694 if (bp->b_kvasize == 0) { 1695 KASSERT(bp->b_kvabase == unmapped_buf && 1696 bp->b_data == unmapped_buf, 1697 ("Leaked KVA space on %p", bp)); 1698 } else if (buf_mapped(bp)) 1699 BUF_CHECK_MAPPED(bp); 1700 else 1701 BUF_CHECK_UNMAPPED(bp); 1702 #endif 1703 if (bp->b_kvasize == 0) 1704 return; 1705 1706 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, bp->b_kvasize); 1707 atomic_subtract_long(&bufkvaspace, bp->b_kvasize); 1708 atomic_add_int(&buffreekvacnt, 1); 1709 bp->b_data = bp->b_kvabase = unmapped_buf; 1710 bp->b_kvasize = 0; 1711 } 1712 1713 /* 1714 * bufkva_alloc: 1715 * 1716 * Allocate the buffer KVA and set b_kvasize and b_kvabase. 1717 */ 1718 static int 1719 bufkva_alloc(struct buf *bp, int maxsize, int gbflags) 1720 { 1721 vm_offset_t addr; 1722 int error; 1723 1724 KASSERT((gbflags & GB_UNMAPPED) == 0 || (gbflags & GB_KVAALLOC) != 0, 1725 ("Invalid gbflags 0x%x in %s", gbflags, __func__)); 1726 1727 bufkva_free(bp); 1728 1729 addr = 0; 1730 error = vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr); 1731 if (error != 0) { 1732 /* 1733 * Buffer map is too fragmented. Request the caller 1734 * to defragment the map. 1735 */ 1736 return (error); 1737 } 1738 bp->b_kvabase = (caddr_t)addr; 1739 bp->b_kvasize = maxsize; 1740 atomic_add_long(&bufkvaspace, bp->b_kvasize); 1741 if ((gbflags & GB_UNMAPPED) != 0) { 1742 bp->b_data = unmapped_buf; 1743 BUF_CHECK_UNMAPPED(bp); 1744 } else { 1745 bp->b_data = bp->b_kvabase; 1746 BUF_CHECK_MAPPED(bp); 1747 } 1748 return (0); 1749 } 1750 1751 /* 1752 * bufkva_reclaim: 1753 * 1754 * Reclaim buffer kva by freeing buffers holding kva. This is a vmem 1755 * callback that fires to avoid returning failure. 1756 */ 1757 static void 1758 bufkva_reclaim(vmem_t *vmem, int flags) 1759 { 1760 int i; 1761 1762 for (i = 0; i < 5; i++) 1763 if (buf_scan(true) != 0) 1764 break; 1765 return; 1766 } 1767 1768 1769 /* 1770 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 1771 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 1772 * the buffer is valid and we do not have to do anything. 1773 */ 1774 void 1775 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, 1776 int cnt, struct ucred * cred) 1777 { 1778 struct buf *rabp; 1779 int i; 1780 1781 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 1782 if (inmem(vp, *rablkno)) 1783 continue; 1784 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 1785 1786 if ((rabp->b_flags & B_CACHE) == 0) { 1787 if (!TD_IS_IDLETHREAD(curthread)) 1788 curthread->td_ru.ru_inblock++; 1789 rabp->b_flags |= B_ASYNC; 1790 rabp->b_flags &= ~B_INVAL; 1791 rabp->b_ioflags &= ~BIO_ERROR; 1792 rabp->b_iocmd = BIO_READ; 1793 if (rabp->b_rcred == NOCRED && cred != NOCRED) 1794 rabp->b_rcred = crhold(cred); 1795 vfs_busy_pages(rabp, 0); 1796 BUF_KERNPROC(rabp); 1797 rabp->b_iooffset = dbtob(rabp->b_blkno); 1798 bstrategy(rabp); 1799 } else { 1800 brelse(rabp); 1801 } 1802 } 1803 } 1804 1805 /* 1806 * Entry point for bread() and breadn() via #defines in sys/buf.h. 1807 * 1808 * Get a buffer with the specified data. Look in the cache first. We 1809 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 1810 * is set, the buffer is valid and we do not have to do anything, see 1811 * getblk(). Also starts asynchronous I/O on read-ahead blocks. 1812 * 1813 * Always return a NULL buffer pointer (in bpp) when returning an error. 1814 */ 1815 int 1816 breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno, 1817 int *rabsize, int cnt, struct ucred *cred, int flags, struct buf **bpp) 1818 { 1819 struct buf *bp; 1820 int rv = 0, readwait = 0; 1821 1822 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 1823 /* 1824 * Can only return NULL if GB_LOCK_NOWAIT flag is specified. 1825 */ 1826 *bpp = bp = getblk(vp, blkno, size, 0, 0, flags); 1827 if (bp == NULL) 1828 return (EBUSY); 1829 1830 /* if not found in cache, do some I/O */ 1831 if ((bp->b_flags & B_CACHE) == 0) { 1832 if (!TD_IS_IDLETHREAD(curthread)) 1833 curthread->td_ru.ru_inblock++; 1834 bp->b_iocmd = BIO_READ; 1835 bp->b_flags &= ~B_INVAL; 1836 bp->b_ioflags &= ~BIO_ERROR; 1837 if (bp->b_rcred == NOCRED && cred != NOCRED) 1838 bp->b_rcred = crhold(cred); 1839 vfs_busy_pages(bp, 0); 1840 bp->b_iooffset = dbtob(bp->b_blkno); 1841 bstrategy(bp); 1842 ++readwait; 1843 } 1844 1845 breada(vp, rablkno, rabsize, cnt, cred); 1846 1847 if (readwait) { 1848 rv = bufwait(bp); 1849 if (rv != 0) { 1850 brelse(bp); 1851 *bpp = NULL; 1852 } 1853 } 1854 return (rv); 1855 } 1856 1857 /* 1858 * Write, release buffer on completion. (Done by iodone 1859 * if async). Do not bother writing anything if the buffer 1860 * is invalid. 1861 * 1862 * Note that we set B_CACHE here, indicating that buffer is 1863 * fully valid and thus cacheable. This is true even of NFS 1864 * now so we set it generally. This could be set either here 1865 * or in biodone() since the I/O is synchronous. We put it 1866 * here. 1867 */ 1868 int 1869 bufwrite(struct buf *bp) 1870 { 1871 int oldflags; 1872 struct vnode *vp; 1873 long space; 1874 int vp_md; 1875 1876 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1877 if ((bp->b_bufobj->bo_flag & BO_DEAD) != 0) { 1878 bp->b_flags |= B_INVAL | B_RELBUF; 1879 bp->b_flags &= ~B_CACHE; 1880 brelse(bp); 1881 return (ENXIO); 1882 } 1883 if (bp->b_flags & B_INVAL) { 1884 brelse(bp); 1885 return (0); 1886 } 1887 1888 if (bp->b_flags & B_BARRIER) 1889 barrierwrites++; 1890 1891 oldflags = bp->b_flags; 1892 1893 BUF_ASSERT_HELD(bp); 1894 1895 if (bp->b_pin_count > 0) 1896 bunpin_wait(bp); 1897 1898 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 1899 ("FFS background buffer should not get here %p", bp)); 1900 1901 vp = bp->b_vp; 1902 if (vp) 1903 vp_md = vp->v_vflag & VV_MD; 1904 else 1905 vp_md = 0; 1906 1907 /* 1908 * Mark the buffer clean. Increment the bufobj write count 1909 * before bundirty() call, to prevent other thread from seeing 1910 * empty dirty list and zero counter for writes in progress, 1911 * falsely indicating that the bufobj is clean. 1912 */ 1913 bufobj_wref(bp->b_bufobj); 1914 bundirty(bp); 1915 1916 bp->b_flags &= ~B_DONE; 1917 bp->b_ioflags &= ~BIO_ERROR; 1918 bp->b_flags |= B_CACHE; 1919 bp->b_iocmd = BIO_WRITE; 1920 1921 vfs_busy_pages(bp, 1); 1922 1923 /* 1924 * Normal bwrites pipeline writes 1925 */ 1926 bp->b_runningbufspace = bp->b_bufsize; 1927 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace); 1928 1929 if (!TD_IS_IDLETHREAD(curthread)) 1930 curthread->td_ru.ru_oublock++; 1931 if (oldflags & B_ASYNC) 1932 BUF_KERNPROC(bp); 1933 bp->b_iooffset = dbtob(bp->b_blkno); 1934 bstrategy(bp); 1935 1936 if ((oldflags & B_ASYNC) == 0) { 1937 int rtval = bufwait(bp); 1938 brelse(bp); 1939 return (rtval); 1940 } else if (space > hirunningspace) { 1941 /* 1942 * don't allow the async write to saturate the I/O 1943 * system. We will not deadlock here because 1944 * we are blocking waiting for I/O that is already in-progress 1945 * to complete. We do not block here if it is the update 1946 * or syncer daemon trying to clean up as that can lead 1947 * to deadlock. 1948 */ 1949 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 1950 waitrunningbufspace(); 1951 } 1952 1953 return (0); 1954 } 1955 1956 void 1957 bufbdflush(struct bufobj *bo, struct buf *bp) 1958 { 1959 struct buf *nbp; 1960 1961 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 1962 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 1963 altbufferflushes++; 1964 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 1965 BO_LOCK(bo); 1966 /* 1967 * Try to find a buffer to flush. 1968 */ 1969 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 1970 if ((nbp->b_vflags & BV_BKGRDINPROG) || 1971 BUF_LOCK(nbp, 1972 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 1973 continue; 1974 if (bp == nbp) 1975 panic("bdwrite: found ourselves"); 1976 BO_UNLOCK(bo); 1977 /* Don't countdeps with the bo lock held. */ 1978 if (buf_countdeps(nbp, 0)) { 1979 BO_LOCK(bo); 1980 BUF_UNLOCK(nbp); 1981 continue; 1982 } 1983 if (nbp->b_flags & B_CLUSTEROK) { 1984 vfs_bio_awrite(nbp); 1985 } else { 1986 bremfree(nbp); 1987 bawrite(nbp); 1988 } 1989 dirtybufferflushes++; 1990 break; 1991 } 1992 if (nbp == NULL) 1993 BO_UNLOCK(bo); 1994 } 1995 } 1996 1997 /* 1998 * Delayed write. (Buffer is marked dirty). Do not bother writing 1999 * anything if the buffer is marked invalid. 2000 * 2001 * Note that since the buffer must be completely valid, we can safely 2002 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 2003 * biodone() in order to prevent getblk from writing the buffer 2004 * out synchronously. 2005 */ 2006 void 2007 bdwrite(struct buf *bp) 2008 { 2009 struct thread *td = curthread; 2010 struct vnode *vp; 2011 struct bufobj *bo; 2012 2013 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2014 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2015 KASSERT((bp->b_flags & B_BARRIER) == 0, 2016 ("Barrier request in delayed write %p", bp)); 2017 BUF_ASSERT_HELD(bp); 2018 2019 if (bp->b_flags & B_INVAL) { 2020 brelse(bp); 2021 return; 2022 } 2023 2024 /* 2025 * If we have too many dirty buffers, don't create any more. 2026 * If we are wildly over our limit, then force a complete 2027 * cleanup. Otherwise, just keep the situation from getting 2028 * out of control. Note that we have to avoid a recursive 2029 * disaster and not try to clean up after our own cleanup! 2030 */ 2031 vp = bp->b_vp; 2032 bo = bp->b_bufobj; 2033 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 2034 td->td_pflags |= TDP_INBDFLUSH; 2035 BO_BDFLUSH(bo, bp); 2036 td->td_pflags &= ~TDP_INBDFLUSH; 2037 } else 2038 recursiveflushes++; 2039 2040 bdirty(bp); 2041 /* 2042 * Set B_CACHE, indicating that the buffer is fully valid. This is 2043 * true even of NFS now. 2044 */ 2045 bp->b_flags |= B_CACHE; 2046 2047 /* 2048 * This bmap keeps the system from needing to do the bmap later, 2049 * perhaps when the system is attempting to do a sync. Since it 2050 * is likely that the indirect block -- or whatever other datastructure 2051 * that the filesystem needs is still in memory now, it is a good 2052 * thing to do this. Note also, that if the pageout daemon is 2053 * requesting a sync -- there might not be enough memory to do 2054 * the bmap then... So, this is important to do. 2055 */ 2056 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 2057 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 2058 } 2059 2060 /* 2061 * Set the *dirty* buffer range based upon the VM system dirty 2062 * pages. 2063 * 2064 * Mark the buffer pages as clean. We need to do this here to 2065 * satisfy the vnode_pager and the pageout daemon, so that it 2066 * thinks that the pages have been "cleaned". Note that since 2067 * the pages are in a delayed write buffer -- the VFS layer 2068 * "will" see that the pages get written out on the next sync, 2069 * or perhaps the cluster will be completed. 2070 */ 2071 vfs_clean_pages_dirty_buf(bp); 2072 bqrelse(bp); 2073 2074 /* 2075 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 2076 * due to the softdep code. 2077 */ 2078 } 2079 2080 /* 2081 * bdirty: 2082 * 2083 * Turn buffer into delayed write request. We must clear BIO_READ and 2084 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 2085 * itself to properly update it in the dirty/clean lists. We mark it 2086 * B_DONE to ensure that any asynchronization of the buffer properly 2087 * clears B_DONE ( else a panic will occur later ). 2088 * 2089 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 2090 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 2091 * should only be called if the buffer is known-good. 2092 * 2093 * Since the buffer is not on a queue, we do not update the numfreebuffers 2094 * count. 2095 * 2096 * The buffer must be on QUEUE_NONE. 2097 */ 2098 void 2099 bdirty(struct buf *bp) 2100 { 2101 2102 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 2103 bp, bp->b_vp, bp->b_flags); 2104 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2105 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 2106 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 2107 BUF_ASSERT_HELD(bp); 2108 bp->b_flags &= ~(B_RELBUF); 2109 bp->b_iocmd = BIO_WRITE; 2110 2111 if ((bp->b_flags & B_DELWRI) == 0) { 2112 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 2113 reassignbuf(bp); 2114 bdirtyadd(); 2115 } 2116 } 2117 2118 /* 2119 * bundirty: 2120 * 2121 * Clear B_DELWRI for buffer. 2122 * 2123 * Since the buffer is not on a queue, we do not update the numfreebuffers 2124 * count. 2125 * 2126 * The buffer must be on QUEUE_NONE. 2127 */ 2128 2129 void 2130 bundirty(struct buf *bp) 2131 { 2132 2133 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2134 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2135 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 2136 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 2137 BUF_ASSERT_HELD(bp); 2138 2139 if (bp->b_flags & B_DELWRI) { 2140 bp->b_flags &= ~B_DELWRI; 2141 reassignbuf(bp); 2142 bdirtysub(); 2143 } 2144 /* 2145 * Since it is now being written, we can clear its deferred write flag. 2146 */ 2147 bp->b_flags &= ~B_DEFERRED; 2148 } 2149 2150 /* 2151 * bawrite: 2152 * 2153 * Asynchronous write. Start output on a buffer, but do not wait for 2154 * it to complete. The buffer is released when the output completes. 2155 * 2156 * bwrite() ( or the VOP routine anyway ) is responsible for handling 2157 * B_INVAL buffers. Not us. 2158 */ 2159 void 2160 bawrite(struct buf *bp) 2161 { 2162 2163 bp->b_flags |= B_ASYNC; 2164 (void) bwrite(bp); 2165 } 2166 2167 /* 2168 * babarrierwrite: 2169 * 2170 * Asynchronous barrier write. Start output on a buffer, but do not 2171 * wait for it to complete. Place a write barrier after this write so 2172 * that this buffer and all buffers written before it are committed to 2173 * the disk before any buffers written after this write are committed 2174 * to the disk. The buffer is released when the output completes. 2175 */ 2176 void 2177 babarrierwrite(struct buf *bp) 2178 { 2179 2180 bp->b_flags |= B_ASYNC | B_BARRIER; 2181 (void) bwrite(bp); 2182 } 2183 2184 /* 2185 * bbarrierwrite: 2186 * 2187 * Synchronous barrier write. Start output on a buffer and wait for 2188 * it to complete. Place a write barrier after this write so that 2189 * this buffer and all buffers written before it are committed to 2190 * the disk before any buffers written after this write are committed 2191 * to the disk. The buffer is released when the output completes. 2192 */ 2193 int 2194 bbarrierwrite(struct buf *bp) 2195 { 2196 2197 bp->b_flags |= B_BARRIER; 2198 return (bwrite(bp)); 2199 } 2200 2201 /* 2202 * bwillwrite: 2203 * 2204 * Called prior to the locking of any vnodes when we are expecting to 2205 * write. We do not want to starve the buffer cache with too many 2206 * dirty buffers so we block here. By blocking prior to the locking 2207 * of any vnodes we attempt to avoid the situation where a locked vnode 2208 * prevents the various system daemons from flushing related buffers. 2209 */ 2210 void 2211 bwillwrite(void) 2212 { 2213 2214 if (numdirtybuffers >= hidirtybuffers) { 2215 mtx_lock(&bdirtylock); 2216 while (numdirtybuffers >= hidirtybuffers) { 2217 bdirtywait = 1; 2218 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4), 2219 "flswai", 0); 2220 } 2221 mtx_unlock(&bdirtylock); 2222 } 2223 } 2224 2225 /* 2226 * Return true if we have too many dirty buffers. 2227 */ 2228 int 2229 buf_dirty_count_severe(void) 2230 { 2231 2232 return(numdirtybuffers >= hidirtybuffers); 2233 } 2234 2235 /* 2236 * brelse: 2237 * 2238 * Release a busy buffer and, if requested, free its resources. The 2239 * buffer will be stashed in the appropriate bufqueue[] allowing it 2240 * to be accessed later as a cache entity or reused for other purposes. 2241 */ 2242 void 2243 brelse(struct buf *bp) 2244 { 2245 int qindex; 2246 2247 /* 2248 * Many function erroneously call brelse with a NULL bp under rare 2249 * error conditions. Simply return when called with a NULL bp. 2250 */ 2251 if (bp == NULL) 2252 return; 2253 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 2254 bp, bp->b_vp, bp->b_flags); 2255 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 2256 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 2257 KASSERT((bp->b_flags & B_VMIO) != 0 || (bp->b_flags & B_NOREUSE) == 0, 2258 ("brelse: non-VMIO buffer marked NOREUSE")); 2259 2260 if (BUF_LOCKRECURSED(bp)) { 2261 /* 2262 * Do not process, in particular, do not handle the 2263 * B_INVAL/B_RELBUF and do not release to free list. 2264 */ 2265 BUF_UNLOCK(bp); 2266 return; 2267 } 2268 2269 if (bp->b_flags & B_MANAGED) { 2270 bqrelse(bp); 2271 return; 2272 } 2273 2274 if ((bp->b_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) { 2275 BO_LOCK(bp->b_bufobj); 2276 bp->b_vflags &= ~BV_BKGRDERR; 2277 BO_UNLOCK(bp->b_bufobj); 2278 bdirty(bp); 2279 } 2280 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 2281 !(bp->b_flags & B_INVAL)) { 2282 /* 2283 * Failed write, redirty. Must clear BIO_ERROR to prevent 2284 * pages from being scrapped. 2285 */ 2286 bp->b_ioflags &= ~BIO_ERROR; 2287 bdirty(bp); 2288 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 2289 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 2290 /* 2291 * Either a failed read I/O or we were asked to free or not 2292 * cache the buffer. 2293 */ 2294 bp->b_flags |= B_INVAL; 2295 if (!LIST_EMPTY(&bp->b_dep)) 2296 buf_deallocate(bp); 2297 if (bp->b_flags & B_DELWRI) 2298 bdirtysub(); 2299 bp->b_flags &= ~(B_DELWRI | B_CACHE); 2300 if ((bp->b_flags & B_VMIO) == 0) { 2301 allocbuf(bp, 0); 2302 if (bp->b_vp) 2303 brelvp(bp); 2304 } 2305 } 2306 2307 /* 2308 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_truncate() 2309 * is called with B_DELWRI set, the underlying pages may wind up 2310 * getting freed causing a previous write (bdwrite()) to get 'lost' 2311 * because pages associated with a B_DELWRI bp are marked clean. 2312 * 2313 * We still allow the B_INVAL case to call vfs_vmio_truncate(), even 2314 * if B_DELWRI is set. 2315 */ 2316 if (bp->b_flags & B_DELWRI) 2317 bp->b_flags &= ~B_RELBUF; 2318 2319 /* 2320 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 2321 * constituted, not even NFS buffers now. Two flags effect this. If 2322 * B_INVAL, the struct buf is invalidated but the VM object is kept 2323 * around ( i.e. so it is trivial to reconstitute the buffer later ). 2324 * 2325 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 2326 * invalidated. BIO_ERROR cannot be set for a failed write unless the 2327 * buffer is also B_INVAL because it hits the re-dirtying code above. 2328 * 2329 * Normally we can do this whether a buffer is B_DELWRI or not. If 2330 * the buffer is an NFS buffer, it is tracking piecemeal writes or 2331 * the commit state and we cannot afford to lose the buffer. If the 2332 * buffer has a background write in progress, we need to keep it 2333 * around to prevent it from being reconstituted and starting a second 2334 * background write. 2335 */ 2336 if ((bp->b_flags & B_VMIO) && (bp->b_flags & B_NOCACHE || 2337 (bp->b_ioflags & BIO_ERROR && bp->b_iocmd == BIO_READ)) && 2338 !(bp->b_vp->v_mount != NULL && 2339 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 2340 !vn_isdisk(bp->b_vp, NULL) && (bp->b_flags & B_DELWRI))) { 2341 vfs_vmio_invalidate(bp); 2342 allocbuf(bp, 0); 2343 } 2344 2345 if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0 || 2346 (bp->b_flags & (B_DELWRI | B_NOREUSE)) == B_NOREUSE) { 2347 allocbuf(bp, 0); 2348 bp->b_flags &= ~B_NOREUSE; 2349 if (bp->b_vp != NULL) 2350 brelvp(bp); 2351 } 2352 2353 /* 2354 * If the buffer has junk contents signal it and eventually 2355 * clean up B_DELWRI and diassociate the vnode so that gbincore() 2356 * doesn't find it. 2357 */ 2358 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 2359 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 2360 bp->b_flags |= B_INVAL; 2361 if (bp->b_flags & B_INVAL) { 2362 if (bp->b_flags & B_DELWRI) 2363 bundirty(bp); 2364 if (bp->b_vp) 2365 brelvp(bp); 2366 } 2367 2368 /* buffers with no memory */ 2369 if (bp->b_bufsize == 0) { 2370 buf_free(bp); 2371 return; 2372 } 2373 /* buffers with junk contents */ 2374 if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 2375 (bp->b_ioflags & BIO_ERROR)) { 2376 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 2377 if (bp->b_vflags & BV_BKGRDINPROG) 2378 panic("losing buffer 2"); 2379 qindex = QUEUE_CLEAN; 2380 bp->b_flags |= B_AGE; 2381 /* remaining buffers */ 2382 } else if (bp->b_flags & B_DELWRI) 2383 qindex = QUEUE_DIRTY; 2384 else 2385 qindex = QUEUE_CLEAN; 2386 2387 binsfree(bp, qindex); 2388 2389 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 2390 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 2391 panic("brelse: not dirty"); 2392 /* unlock */ 2393 BUF_UNLOCK(bp); 2394 if (qindex == QUEUE_CLEAN) 2395 bufspace_wakeup(); 2396 } 2397 2398 /* 2399 * Release a buffer back to the appropriate queue but do not try to free 2400 * it. The buffer is expected to be used again soon. 2401 * 2402 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 2403 * biodone() to requeue an async I/O on completion. It is also used when 2404 * known good buffers need to be requeued but we think we may need the data 2405 * again soon. 2406 * 2407 * XXX we should be able to leave the B_RELBUF hint set on completion. 2408 */ 2409 void 2410 bqrelse(struct buf *bp) 2411 { 2412 int qindex; 2413 2414 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2415 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 2416 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 2417 2418 qindex = QUEUE_NONE; 2419 if (BUF_LOCKRECURSED(bp)) { 2420 /* do not release to free list */ 2421 BUF_UNLOCK(bp); 2422 return; 2423 } 2424 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 2425 2426 if (bp->b_flags & B_MANAGED) { 2427 if (bp->b_flags & B_REMFREE) 2428 bremfreef(bp); 2429 goto out; 2430 } 2431 2432 /* buffers with stale but valid contents */ 2433 if ((bp->b_flags & B_DELWRI) != 0 || (bp->b_vflags & (BV_BKGRDINPROG | 2434 BV_BKGRDERR)) == BV_BKGRDERR) { 2435 BO_LOCK(bp->b_bufobj); 2436 bp->b_vflags &= ~BV_BKGRDERR; 2437 BO_UNLOCK(bp->b_bufobj); 2438 qindex = QUEUE_DIRTY; 2439 } else { 2440 if ((bp->b_flags & B_DELWRI) == 0 && 2441 (bp->b_xflags & BX_VNDIRTY)) 2442 panic("bqrelse: not dirty"); 2443 if ((bp->b_flags & B_NOREUSE) != 0) { 2444 brelse(bp); 2445 return; 2446 } 2447 qindex = QUEUE_CLEAN; 2448 } 2449 binsfree(bp, qindex); 2450 2451 out: 2452 /* unlock */ 2453 BUF_UNLOCK(bp); 2454 if (qindex == QUEUE_CLEAN) 2455 bufspace_wakeup(); 2456 } 2457 2458 /* 2459 * Complete I/O to a VMIO backed page. Validate the pages as appropriate, 2460 * restore bogus pages. 2461 */ 2462 static void 2463 vfs_vmio_iodone(struct buf *bp) 2464 { 2465 vm_ooffset_t foff; 2466 vm_page_t m; 2467 vm_object_t obj; 2468 struct vnode *vp; 2469 int bogus, i, iosize; 2470 2471 obj = bp->b_bufobj->bo_object; 2472 KASSERT(obj->paging_in_progress >= bp->b_npages, 2473 ("vfs_vmio_iodone: paging in progress(%d) < b_npages(%d)", 2474 obj->paging_in_progress, bp->b_npages)); 2475 2476 vp = bp->b_vp; 2477 KASSERT(vp->v_holdcnt > 0, 2478 ("vfs_vmio_iodone: vnode %p has zero hold count", vp)); 2479 KASSERT(vp->v_object != NULL, 2480 ("vfs_vmio_iodone: vnode %p has no vm_object", vp)); 2481 2482 foff = bp->b_offset; 2483 KASSERT(bp->b_offset != NOOFFSET, 2484 ("vfs_vmio_iodone: bp %p has no buffer offset", bp)); 2485 2486 bogus = 0; 2487 iosize = bp->b_bcount - bp->b_resid; 2488 VM_OBJECT_WLOCK(obj); 2489 for (i = 0; i < bp->b_npages; i++) { 2490 int resid; 2491 2492 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 2493 if (resid > iosize) 2494 resid = iosize; 2495 2496 /* 2497 * cleanup bogus pages, restoring the originals 2498 */ 2499 m = bp->b_pages[i]; 2500 if (m == bogus_page) { 2501 bogus = 1; 2502 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 2503 if (m == NULL) 2504 panic("biodone: page disappeared!"); 2505 bp->b_pages[i] = m; 2506 } else if ((bp->b_iocmd == BIO_READ) && resid > 0) { 2507 /* 2508 * In the write case, the valid and clean bits are 2509 * already changed correctly ( see bdwrite() ), so we 2510 * only need to do this here in the read case. 2511 */ 2512 KASSERT((m->dirty & vm_page_bits(foff & PAGE_MASK, 2513 resid)) == 0, ("vfs_vmio_iodone: page %p " 2514 "has unexpected dirty bits", m)); 2515 vfs_page_set_valid(bp, foff, m); 2516 } 2517 KASSERT(OFF_TO_IDX(foff) == m->pindex, 2518 ("vfs_vmio_iodone: foff(%jd)/pindex(%ju) mismatch", 2519 (intmax_t)foff, (uintmax_t)m->pindex)); 2520 2521 vm_page_sunbusy(m); 2522 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2523 iosize -= resid; 2524 } 2525 vm_object_pip_wakeupn(obj, bp->b_npages); 2526 VM_OBJECT_WUNLOCK(obj); 2527 if (bogus && buf_mapped(bp)) { 2528 BUF_CHECK_MAPPED(bp); 2529 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 2530 bp->b_pages, bp->b_npages); 2531 } 2532 } 2533 2534 /* 2535 * Unwire a page held by a buf and place it on the appropriate vm queue. 2536 */ 2537 static void 2538 vfs_vmio_unwire(struct buf *bp, vm_page_t m) 2539 { 2540 bool freed; 2541 2542 vm_page_lock(m); 2543 if (vm_page_unwire(m, PQ_NONE)) { 2544 /* 2545 * Determine if the page should be freed before adding 2546 * it to the inactive queue. 2547 */ 2548 if (m->valid == 0) { 2549 freed = !vm_page_busied(m); 2550 if (freed) 2551 vm_page_free(m); 2552 } else if ((bp->b_flags & B_DIRECT) != 0) 2553 freed = vm_page_try_to_free(m); 2554 else 2555 freed = false; 2556 if (!freed) { 2557 /* 2558 * If the page is unlikely to be reused, let the 2559 * VM know. Otherwise, maintain LRU page 2560 * ordering and put the page at the tail of the 2561 * inactive queue. 2562 */ 2563 if ((bp->b_flags & B_NOREUSE) != 0) 2564 vm_page_deactivate_noreuse(m); 2565 else 2566 vm_page_deactivate(m); 2567 } 2568 } 2569 vm_page_unlock(m); 2570 } 2571 2572 /* 2573 * Perform page invalidation when a buffer is released. The fully invalid 2574 * pages will be reclaimed later in vfs_vmio_truncate(). 2575 */ 2576 static void 2577 vfs_vmio_invalidate(struct buf *bp) 2578 { 2579 vm_object_t obj; 2580 vm_page_t m; 2581 int i, resid, poffset, presid; 2582 2583 if (buf_mapped(bp)) { 2584 BUF_CHECK_MAPPED(bp); 2585 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages); 2586 } else 2587 BUF_CHECK_UNMAPPED(bp); 2588 /* 2589 * Get the base offset and length of the buffer. Note that 2590 * in the VMIO case if the buffer block size is not 2591 * page-aligned then b_data pointer may not be page-aligned. 2592 * But our b_pages[] array *IS* page aligned. 2593 * 2594 * block sizes less then DEV_BSIZE (usually 512) are not 2595 * supported due to the page granularity bits (m->valid, 2596 * m->dirty, etc...). 2597 * 2598 * See man buf(9) for more information 2599 */ 2600 obj = bp->b_bufobj->bo_object; 2601 resid = bp->b_bufsize; 2602 poffset = bp->b_offset & PAGE_MASK; 2603 VM_OBJECT_WLOCK(obj); 2604 for (i = 0; i < bp->b_npages; i++) { 2605 m = bp->b_pages[i]; 2606 if (m == bogus_page) 2607 panic("vfs_vmio_invalidate: Unexpected bogus page."); 2608 bp->b_pages[i] = NULL; 2609 2610 presid = resid > (PAGE_SIZE - poffset) ? 2611 (PAGE_SIZE - poffset) : resid; 2612 KASSERT(presid >= 0, ("brelse: extra page")); 2613 while (vm_page_xbusied(m)) { 2614 vm_page_lock(m); 2615 VM_OBJECT_WUNLOCK(obj); 2616 vm_page_busy_sleep(m, "mbncsh"); 2617 VM_OBJECT_WLOCK(obj); 2618 } 2619 if (pmap_page_wired_mappings(m) == 0) 2620 vm_page_set_invalid(m, poffset, presid); 2621 vfs_vmio_unwire(bp, m); 2622 resid -= presid; 2623 poffset = 0; 2624 } 2625 VM_OBJECT_WUNLOCK(obj); 2626 bp->b_npages = 0; 2627 } 2628 2629 /* 2630 * Page-granular truncation of an existing VMIO buffer. 2631 */ 2632 static void 2633 vfs_vmio_truncate(struct buf *bp, int desiredpages) 2634 { 2635 vm_object_t obj; 2636 vm_page_t m; 2637 int i; 2638 2639 if (bp->b_npages == desiredpages) 2640 return; 2641 2642 if (buf_mapped(bp)) { 2643 BUF_CHECK_MAPPED(bp); 2644 pmap_qremove((vm_offset_t)trunc_page((vm_offset_t)bp->b_data) + 2645 (desiredpages << PAGE_SHIFT), bp->b_npages - desiredpages); 2646 } else 2647 BUF_CHECK_UNMAPPED(bp); 2648 obj = bp->b_bufobj->bo_object; 2649 if (obj != NULL) 2650 VM_OBJECT_WLOCK(obj); 2651 for (i = desiredpages; i < bp->b_npages; i++) { 2652 m = bp->b_pages[i]; 2653 KASSERT(m != bogus_page, ("allocbuf: bogus page found")); 2654 bp->b_pages[i] = NULL; 2655 vfs_vmio_unwire(bp, m); 2656 } 2657 if (obj != NULL) 2658 VM_OBJECT_WUNLOCK(obj); 2659 bp->b_npages = desiredpages; 2660 } 2661 2662 /* 2663 * Byte granular extension of VMIO buffers. 2664 */ 2665 static void 2666 vfs_vmio_extend(struct buf *bp, int desiredpages, int size) 2667 { 2668 /* 2669 * We are growing the buffer, possibly in a 2670 * byte-granular fashion. 2671 */ 2672 vm_object_t obj; 2673 vm_offset_t toff; 2674 vm_offset_t tinc; 2675 vm_page_t m; 2676 2677 /* 2678 * Step 1, bring in the VM pages from the object, allocating 2679 * them if necessary. We must clear B_CACHE if these pages 2680 * are not valid for the range covered by the buffer. 2681 */ 2682 obj = bp->b_bufobj->bo_object; 2683 VM_OBJECT_WLOCK(obj); 2684 while (bp->b_npages < desiredpages) { 2685 /* 2686 * We must allocate system pages since blocking 2687 * here could interfere with paging I/O, no 2688 * matter which process we are. 2689 * 2690 * Only exclusive busy can be tested here. 2691 * Blocking on shared busy might lead to 2692 * deadlocks once allocbuf() is called after 2693 * pages are vfs_busy_pages(). 2694 */ 2695 m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) + bp->b_npages, 2696 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM | 2697 VM_ALLOC_WIRED | VM_ALLOC_IGN_SBUSY | 2698 VM_ALLOC_COUNT(desiredpages - bp->b_npages)); 2699 if (m->valid == 0) 2700 bp->b_flags &= ~B_CACHE; 2701 bp->b_pages[bp->b_npages] = m; 2702 ++bp->b_npages; 2703 } 2704 2705 /* 2706 * Step 2. We've loaded the pages into the buffer, 2707 * we have to figure out if we can still have B_CACHE 2708 * set. Note that B_CACHE is set according to the 2709 * byte-granular range ( bcount and size ), not the 2710 * aligned range ( newbsize ). 2711 * 2712 * The VM test is against m->valid, which is DEV_BSIZE 2713 * aligned. Needless to say, the validity of the data 2714 * needs to also be DEV_BSIZE aligned. Note that this 2715 * fails with NFS if the server or some other client 2716 * extends the file's EOF. If our buffer is resized, 2717 * B_CACHE may remain set! XXX 2718 */ 2719 toff = bp->b_bcount; 2720 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 2721 while ((bp->b_flags & B_CACHE) && toff < size) { 2722 vm_pindex_t pi; 2723 2724 if (tinc > (size - toff)) 2725 tinc = size - toff; 2726 pi = ((bp->b_offset & PAGE_MASK) + toff) >> PAGE_SHIFT; 2727 m = bp->b_pages[pi]; 2728 vfs_buf_test_cache(bp, bp->b_offset, toff, tinc, m); 2729 toff += tinc; 2730 tinc = PAGE_SIZE; 2731 } 2732 VM_OBJECT_WUNLOCK(obj); 2733 2734 /* 2735 * Step 3, fixup the KVA pmap. 2736 */ 2737 if (buf_mapped(bp)) 2738 bpmap_qenter(bp); 2739 else 2740 BUF_CHECK_UNMAPPED(bp); 2741 } 2742 2743 /* 2744 * Check to see if a block at a particular lbn is available for a clustered 2745 * write. 2746 */ 2747 static int 2748 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 2749 { 2750 struct buf *bpa; 2751 int match; 2752 2753 match = 0; 2754 2755 /* If the buf isn't in core skip it */ 2756 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 2757 return (0); 2758 2759 /* If the buf is busy we don't want to wait for it */ 2760 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2761 return (0); 2762 2763 /* Only cluster with valid clusterable delayed write buffers */ 2764 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 2765 (B_DELWRI | B_CLUSTEROK)) 2766 goto done; 2767 2768 if (bpa->b_bufsize != size) 2769 goto done; 2770 2771 /* 2772 * Check to see if it is in the expected place on disk and that the 2773 * block has been mapped. 2774 */ 2775 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 2776 match = 1; 2777 done: 2778 BUF_UNLOCK(bpa); 2779 return (match); 2780 } 2781 2782 /* 2783 * vfs_bio_awrite: 2784 * 2785 * Implement clustered async writes for clearing out B_DELWRI buffers. 2786 * This is much better then the old way of writing only one buffer at 2787 * a time. Note that we may not be presented with the buffers in the 2788 * correct order, so we search for the cluster in both directions. 2789 */ 2790 int 2791 vfs_bio_awrite(struct buf *bp) 2792 { 2793 struct bufobj *bo; 2794 int i; 2795 int j; 2796 daddr_t lblkno = bp->b_lblkno; 2797 struct vnode *vp = bp->b_vp; 2798 int ncl; 2799 int nwritten; 2800 int size; 2801 int maxcl; 2802 int gbflags; 2803 2804 bo = &vp->v_bufobj; 2805 gbflags = (bp->b_data == unmapped_buf) ? GB_UNMAPPED : 0; 2806 /* 2807 * right now we support clustered writing only to regular files. If 2808 * we find a clusterable block we could be in the middle of a cluster 2809 * rather then at the beginning. 2810 */ 2811 if ((vp->v_type == VREG) && 2812 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 2813 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 2814 2815 size = vp->v_mount->mnt_stat.f_iosize; 2816 maxcl = MAXPHYS / size; 2817 2818 BO_RLOCK(bo); 2819 for (i = 1; i < maxcl; i++) 2820 if (vfs_bio_clcheck(vp, size, lblkno + i, 2821 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 2822 break; 2823 2824 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 2825 if (vfs_bio_clcheck(vp, size, lblkno - j, 2826 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 2827 break; 2828 BO_RUNLOCK(bo); 2829 --j; 2830 ncl = i + j; 2831 /* 2832 * this is a possible cluster write 2833 */ 2834 if (ncl != 1) { 2835 BUF_UNLOCK(bp); 2836 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl, 2837 gbflags); 2838 return (nwritten); 2839 } 2840 } 2841 bremfree(bp); 2842 bp->b_flags |= B_ASYNC; 2843 /* 2844 * default (old) behavior, writing out only one block 2845 * 2846 * XXX returns b_bufsize instead of b_bcount for nwritten? 2847 */ 2848 nwritten = bp->b_bufsize; 2849 (void) bwrite(bp); 2850 2851 return (nwritten); 2852 } 2853 2854 /* 2855 * getnewbuf_kva: 2856 * 2857 * Allocate KVA for an empty buf header according to gbflags. 2858 */ 2859 static int 2860 getnewbuf_kva(struct buf *bp, int gbflags, int maxsize) 2861 { 2862 2863 if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_UNMAPPED) { 2864 /* 2865 * In order to keep fragmentation sane we only allocate kva 2866 * in BKVASIZE chunks. XXX with vmem we can do page size. 2867 */ 2868 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2869 2870 if (maxsize != bp->b_kvasize && 2871 bufkva_alloc(bp, maxsize, gbflags)) 2872 return (ENOSPC); 2873 } 2874 return (0); 2875 } 2876 2877 /* 2878 * getnewbuf: 2879 * 2880 * Find and initialize a new buffer header, freeing up existing buffers 2881 * in the bufqueues as necessary. The new buffer is returned locked. 2882 * 2883 * We block if: 2884 * We have insufficient buffer headers 2885 * We have insufficient buffer space 2886 * buffer_arena is too fragmented ( space reservation fails ) 2887 * If we have to flush dirty buffers ( but we try to avoid this ) 2888 * 2889 * The caller is responsible for releasing the reserved bufspace after 2890 * allocbuf() is called. 2891 */ 2892 static struct buf * 2893 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int maxsize, int gbflags) 2894 { 2895 struct buf *bp; 2896 bool metadata, reserved; 2897 2898 bp = NULL; 2899 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 2900 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 2901 if (!unmapped_buf_allowed) 2902 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC); 2903 2904 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 || 2905 vp->v_type == VCHR) 2906 metadata = true; 2907 else 2908 metadata = false; 2909 atomic_add_int(&getnewbufcalls, 1); 2910 reserved = false; 2911 do { 2912 if (reserved == false && 2913 bufspace_reserve(maxsize, metadata) != 0) 2914 continue; 2915 reserved = true; 2916 if ((bp = buf_alloc()) == NULL) 2917 continue; 2918 if (getnewbuf_kva(bp, gbflags, maxsize) == 0) 2919 return (bp); 2920 break; 2921 } while(buf_scan(false) == 0); 2922 2923 if (reserved) 2924 atomic_subtract_long(&bufspace, maxsize); 2925 if (bp != NULL) { 2926 bp->b_flags |= B_INVAL; 2927 brelse(bp); 2928 } 2929 bufspace_wait(vp, gbflags, slpflag, slptimeo); 2930 2931 return (NULL); 2932 } 2933 2934 /* 2935 * buf_daemon: 2936 * 2937 * buffer flushing daemon. Buffers are normally flushed by the 2938 * update daemon but if it cannot keep up this process starts to 2939 * take the load in an attempt to prevent getnewbuf() from blocking. 2940 */ 2941 static struct kproc_desc buf_kp = { 2942 "bufdaemon", 2943 buf_daemon, 2944 &bufdaemonproc 2945 }; 2946 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 2947 2948 static int 2949 buf_flush(struct vnode *vp, int target) 2950 { 2951 int flushed; 2952 2953 flushed = flushbufqueues(vp, target, 0); 2954 if (flushed == 0) { 2955 /* 2956 * Could not find any buffers without rollback 2957 * dependencies, so just write the first one 2958 * in the hopes of eventually making progress. 2959 */ 2960 if (vp != NULL && target > 2) 2961 target /= 2; 2962 flushbufqueues(vp, target, 1); 2963 } 2964 return (flushed); 2965 } 2966 2967 static void 2968 buf_daemon() 2969 { 2970 int lodirty; 2971 2972 /* 2973 * This process needs to be suspended prior to shutdown sync. 2974 */ 2975 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2976 SHUTDOWN_PRI_LAST); 2977 2978 /* 2979 * This process is allowed to take the buffer cache to the limit 2980 */ 2981 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 2982 mtx_lock(&bdlock); 2983 for (;;) { 2984 bd_request = 0; 2985 mtx_unlock(&bdlock); 2986 2987 kproc_suspend_check(bufdaemonproc); 2988 lodirty = lodirtybuffers; 2989 if (bd_speedupreq) { 2990 lodirty = numdirtybuffers / 2; 2991 bd_speedupreq = 0; 2992 } 2993 /* 2994 * Do the flush. Limit the amount of in-transit I/O we 2995 * allow to build up, otherwise we would completely saturate 2996 * the I/O system. 2997 */ 2998 while (numdirtybuffers > lodirty) { 2999 if (buf_flush(NULL, numdirtybuffers - lodirty) == 0) 3000 break; 3001 kern_yield(PRI_USER); 3002 } 3003 3004 /* 3005 * Only clear bd_request if we have reached our low water 3006 * mark. The buf_daemon normally waits 1 second and 3007 * then incrementally flushes any dirty buffers that have 3008 * built up, within reason. 3009 * 3010 * If we were unable to hit our low water mark and couldn't 3011 * find any flushable buffers, we sleep for a short period 3012 * to avoid endless loops on unlockable buffers. 3013 */ 3014 mtx_lock(&bdlock); 3015 if (numdirtybuffers <= lodirtybuffers) { 3016 /* 3017 * We reached our low water mark, reset the 3018 * request and sleep until we are needed again. 3019 * The sleep is just so the suspend code works. 3020 */ 3021 bd_request = 0; 3022 /* 3023 * Do an extra wakeup in case dirty threshold 3024 * changed via sysctl and the explicit transition 3025 * out of shortfall was missed. 3026 */ 3027 bdirtywakeup(); 3028 if (runningbufspace <= lorunningspace) 3029 runningwakeup(); 3030 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 3031 } else { 3032 /* 3033 * We couldn't find any flushable dirty buffers but 3034 * still have too many dirty buffers, we 3035 * have to sleep and try again. (rare) 3036 */ 3037 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 3038 } 3039 } 3040 } 3041 3042 /* 3043 * flushbufqueues: 3044 * 3045 * Try to flush a buffer in the dirty queue. We must be careful to 3046 * free up B_INVAL buffers instead of write them, which NFS is 3047 * particularly sensitive to. 3048 */ 3049 static int flushwithdeps = 0; 3050 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 3051 0, "Number of buffers flushed with dependecies that require rollbacks"); 3052 3053 static int 3054 flushbufqueues(struct vnode *lvp, int target, int flushdeps) 3055 { 3056 struct buf *sentinel; 3057 struct vnode *vp; 3058 struct mount *mp; 3059 struct buf *bp; 3060 int hasdeps; 3061 int flushed; 3062 int queue; 3063 int error; 3064 bool unlock; 3065 3066 flushed = 0; 3067 queue = QUEUE_DIRTY; 3068 bp = NULL; 3069 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 3070 sentinel->b_qindex = QUEUE_SENTINEL; 3071 mtx_lock(&bqlocks[queue]); 3072 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist); 3073 mtx_unlock(&bqlocks[queue]); 3074 while (flushed != target) { 3075 maybe_yield(); 3076 mtx_lock(&bqlocks[queue]); 3077 bp = TAILQ_NEXT(sentinel, b_freelist); 3078 if (bp != NULL) { 3079 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 3080 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel, 3081 b_freelist); 3082 } else { 3083 mtx_unlock(&bqlocks[queue]); 3084 break; 3085 } 3086 /* 3087 * Skip sentinels inserted by other invocations of the 3088 * flushbufqueues(), taking care to not reorder them. 3089 * 3090 * Only flush the buffers that belong to the 3091 * vnode locked by the curthread. 3092 */ 3093 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL && 3094 bp->b_vp != lvp)) { 3095 mtx_unlock(&bqlocks[queue]); 3096 continue; 3097 } 3098 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL); 3099 mtx_unlock(&bqlocks[queue]); 3100 if (error != 0) 3101 continue; 3102 if (bp->b_pin_count > 0) { 3103 BUF_UNLOCK(bp); 3104 continue; 3105 } 3106 /* 3107 * BKGRDINPROG can only be set with the buf and bufobj 3108 * locks both held. We tolerate a race to clear it here. 3109 */ 3110 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 3111 (bp->b_flags & B_DELWRI) == 0) { 3112 BUF_UNLOCK(bp); 3113 continue; 3114 } 3115 if (bp->b_flags & B_INVAL) { 3116 bremfreef(bp); 3117 brelse(bp); 3118 flushed++; 3119 continue; 3120 } 3121 3122 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 3123 if (flushdeps == 0) { 3124 BUF_UNLOCK(bp); 3125 continue; 3126 } 3127 hasdeps = 1; 3128 } else 3129 hasdeps = 0; 3130 /* 3131 * We must hold the lock on a vnode before writing 3132 * one of its buffers. Otherwise we may confuse, or 3133 * in the case of a snapshot vnode, deadlock the 3134 * system. 3135 * 3136 * The lock order here is the reverse of the normal 3137 * of vnode followed by buf lock. This is ok because 3138 * the NOWAIT will prevent deadlock. 3139 */ 3140 vp = bp->b_vp; 3141 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 3142 BUF_UNLOCK(bp); 3143 continue; 3144 } 3145 if (lvp == NULL) { 3146 unlock = true; 3147 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT); 3148 } else { 3149 ASSERT_VOP_LOCKED(vp, "getbuf"); 3150 unlock = false; 3151 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 : 3152 vn_lock(vp, LK_TRYUPGRADE); 3153 } 3154 if (error == 0) { 3155 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 3156 bp, bp->b_vp, bp->b_flags); 3157 if (curproc == bufdaemonproc) { 3158 vfs_bio_awrite(bp); 3159 } else { 3160 bremfree(bp); 3161 bwrite(bp); 3162 notbufdflushes++; 3163 } 3164 vn_finished_write(mp); 3165 if (unlock) 3166 VOP_UNLOCK(vp, 0); 3167 flushwithdeps += hasdeps; 3168 flushed++; 3169 3170 /* 3171 * Sleeping on runningbufspace while holding 3172 * vnode lock leads to deadlock. 3173 */ 3174 if (curproc == bufdaemonproc && 3175 runningbufspace > hirunningspace) 3176 waitrunningbufspace(); 3177 continue; 3178 } 3179 vn_finished_write(mp); 3180 BUF_UNLOCK(bp); 3181 } 3182 mtx_lock(&bqlocks[queue]); 3183 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 3184 mtx_unlock(&bqlocks[queue]); 3185 free(sentinel, M_TEMP); 3186 return (flushed); 3187 } 3188 3189 /* 3190 * Check to see if a block is currently memory resident. 3191 */ 3192 struct buf * 3193 incore(struct bufobj *bo, daddr_t blkno) 3194 { 3195 struct buf *bp; 3196 3197 BO_RLOCK(bo); 3198 bp = gbincore(bo, blkno); 3199 BO_RUNLOCK(bo); 3200 return (bp); 3201 } 3202 3203 /* 3204 * Returns true if no I/O is needed to access the 3205 * associated VM object. This is like incore except 3206 * it also hunts around in the VM system for the data. 3207 */ 3208 3209 static int 3210 inmem(struct vnode * vp, daddr_t blkno) 3211 { 3212 vm_object_t obj; 3213 vm_offset_t toff, tinc, size; 3214 vm_page_t m; 3215 vm_ooffset_t off; 3216 3217 ASSERT_VOP_LOCKED(vp, "inmem"); 3218 3219 if (incore(&vp->v_bufobj, blkno)) 3220 return 1; 3221 if (vp->v_mount == NULL) 3222 return 0; 3223 obj = vp->v_object; 3224 if (obj == NULL) 3225 return (0); 3226 3227 size = PAGE_SIZE; 3228 if (size > vp->v_mount->mnt_stat.f_iosize) 3229 size = vp->v_mount->mnt_stat.f_iosize; 3230 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 3231 3232 VM_OBJECT_RLOCK(obj); 3233 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 3234 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 3235 if (!m) 3236 goto notinmem; 3237 tinc = size; 3238 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 3239 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 3240 if (vm_page_is_valid(m, 3241 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 3242 goto notinmem; 3243 } 3244 VM_OBJECT_RUNLOCK(obj); 3245 return 1; 3246 3247 notinmem: 3248 VM_OBJECT_RUNLOCK(obj); 3249 return (0); 3250 } 3251 3252 /* 3253 * Set the dirty range for a buffer based on the status of the dirty 3254 * bits in the pages comprising the buffer. The range is limited 3255 * to the size of the buffer. 3256 * 3257 * Tell the VM system that the pages associated with this buffer 3258 * are clean. This is used for delayed writes where the data is 3259 * going to go to disk eventually without additional VM intevention. 3260 * 3261 * Note that while we only really need to clean through to b_bcount, we 3262 * just go ahead and clean through to b_bufsize. 3263 */ 3264 static void 3265 vfs_clean_pages_dirty_buf(struct buf *bp) 3266 { 3267 vm_ooffset_t foff, noff, eoff; 3268 vm_page_t m; 3269 int i; 3270 3271 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 3272 return; 3273 3274 foff = bp->b_offset; 3275 KASSERT(bp->b_offset != NOOFFSET, 3276 ("vfs_clean_pages_dirty_buf: no buffer offset")); 3277 3278 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 3279 vfs_drain_busy_pages(bp); 3280 vfs_setdirty_locked_object(bp); 3281 for (i = 0; i < bp->b_npages; i++) { 3282 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3283 eoff = noff; 3284 if (eoff > bp->b_offset + bp->b_bufsize) 3285 eoff = bp->b_offset + bp->b_bufsize; 3286 m = bp->b_pages[i]; 3287 vfs_page_set_validclean(bp, foff, m); 3288 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3289 foff = noff; 3290 } 3291 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 3292 } 3293 3294 static void 3295 vfs_setdirty_locked_object(struct buf *bp) 3296 { 3297 vm_object_t object; 3298 int i; 3299 3300 object = bp->b_bufobj->bo_object; 3301 VM_OBJECT_ASSERT_WLOCKED(object); 3302 3303 /* 3304 * We qualify the scan for modified pages on whether the 3305 * object has been flushed yet. 3306 */ 3307 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) { 3308 vm_offset_t boffset; 3309 vm_offset_t eoffset; 3310 3311 /* 3312 * test the pages to see if they have been modified directly 3313 * by users through the VM system. 3314 */ 3315 for (i = 0; i < bp->b_npages; i++) 3316 vm_page_test_dirty(bp->b_pages[i]); 3317 3318 /* 3319 * Calculate the encompassing dirty range, boffset and eoffset, 3320 * (eoffset - boffset) bytes. 3321 */ 3322 3323 for (i = 0; i < bp->b_npages; i++) { 3324 if (bp->b_pages[i]->dirty) 3325 break; 3326 } 3327 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3328 3329 for (i = bp->b_npages - 1; i >= 0; --i) { 3330 if (bp->b_pages[i]->dirty) { 3331 break; 3332 } 3333 } 3334 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3335 3336 /* 3337 * Fit it to the buffer. 3338 */ 3339 3340 if (eoffset > bp->b_bcount) 3341 eoffset = bp->b_bcount; 3342 3343 /* 3344 * If we have a good dirty range, merge with the existing 3345 * dirty range. 3346 */ 3347 3348 if (boffset < eoffset) { 3349 if (bp->b_dirtyoff > boffset) 3350 bp->b_dirtyoff = boffset; 3351 if (bp->b_dirtyend < eoffset) 3352 bp->b_dirtyend = eoffset; 3353 } 3354 } 3355 } 3356 3357 /* 3358 * Allocate the KVA mapping for an existing buffer. 3359 * If an unmapped buffer is provided but a mapped buffer is requested, take 3360 * also care to properly setup mappings between pages and KVA. 3361 */ 3362 static void 3363 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags) 3364 { 3365 int bsize, maxsize, need_mapping, need_kva; 3366 off_t offset; 3367 3368 need_mapping = bp->b_data == unmapped_buf && 3369 (gbflags & GB_UNMAPPED) == 0; 3370 need_kva = bp->b_kvabase == unmapped_buf && 3371 bp->b_data == unmapped_buf && 3372 (gbflags & GB_KVAALLOC) != 0; 3373 if (!need_mapping && !need_kva) 3374 return; 3375 3376 BUF_CHECK_UNMAPPED(bp); 3377 3378 if (need_mapping && bp->b_kvabase != unmapped_buf) { 3379 /* 3380 * Buffer is not mapped, but the KVA was already 3381 * reserved at the time of the instantiation. Use the 3382 * allocated space. 3383 */ 3384 goto has_addr; 3385 } 3386 3387 /* 3388 * Calculate the amount of the address space we would reserve 3389 * if the buffer was mapped. 3390 */ 3391 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize; 3392 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3393 offset = blkno * bsize; 3394 maxsize = size + (offset & PAGE_MASK); 3395 maxsize = imax(maxsize, bsize); 3396 3397 while (bufkva_alloc(bp, maxsize, gbflags) != 0) { 3398 if ((gbflags & GB_NOWAIT_BD) != 0) { 3399 /* 3400 * XXXKIB: defragmentation cannot 3401 * succeed, not sure what else to do. 3402 */ 3403 panic("GB_NOWAIT_BD and GB_UNMAPPED %p", bp); 3404 } 3405 atomic_add_int(&mappingrestarts, 1); 3406 bufspace_wait(bp->b_vp, gbflags, 0, 0); 3407 } 3408 has_addr: 3409 if (need_mapping) { 3410 /* b_offset is handled by bpmap_qenter. */ 3411 bp->b_data = bp->b_kvabase; 3412 BUF_CHECK_MAPPED(bp); 3413 bpmap_qenter(bp); 3414 } 3415 } 3416 3417 /* 3418 * getblk: 3419 * 3420 * Get a block given a specified block and offset into a file/device. 3421 * The buffers B_DONE bit will be cleared on return, making it almost 3422 * ready for an I/O initiation. B_INVAL may or may not be set on 3423 * return. The caller should clear B_INVAL prior to initiating a 3424 * READ. 3425 * 3426 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 3427 * an existing buffer. 3428 * 3429 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 3430 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 3431 * and then cleared based on the backing VM. If the previous buffer is 3432 * non-0-sized but invalid, B_CACHE will be cleared. 3433 * 3434 * If getblk() must create a new buffer, the new buffer is returned with 3435 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 3436 * case it is returned with B_INVAL clear and B_CACHE set based on the 3437 * backing VM. 3438 * 3439 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 3440 * B_CACHE bit is clear. 3441 * 3442 * What this means, basically, is that the caller should use B_CACHE to 3443 * determine whether the buffer is fully valid or not and should clear 3444 * B_INVAL prior to issuing a read. If the caller intends to validate 3445 * the buffer by loading its data area with something, the caller needs 3446 * to clear B_INVAL. If the caller does this without issuing an I/O, 3447 * the caller should set B_CACHE ( as an optimization ), else the caller 3448 * should issue the I/O and biodone() will set B_CACHE if the I/O was 3449 * a write attempt or if it was a successfull read. If the caller 3450 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 3451 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 3452 */ 3453 struct buf * 3454 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3455 int flags) 3456 { 3457 struct buf *bp; 3458 struct bufobj *bo; 3459 int bsize, error, maxsize, vmio; 3460 off_t offset; 3461 3462 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 3463 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3464 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3465 ASSERT_VOP_LOCKED(vp, "getblk"); 3466 if (size > MAXBCACHEBUF) 3467 panic("getblk: size(%d) > MAXBCACHEBUF(%d)\n", size, 3468 MAXBCACHEBUF); 3469 if (!unmapped_buf_allowed) 3470 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3471 3472 bo = &vp->v_bufobj; 3473 loop: 3474 BO_RLOCK(bo); 3475 bp = gbincore(bo, blkno); 3476 if (bp != NULL) { 3477 int lockflags; 3478 /* 3479 * Buffer is in-core. If the buffer is not busy nor managed, 3480 * it must be on a queue. 3481 */ 3482 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 3483 3484 if (flags & GB_LOCK_NOWAIT) 3485 lockflags |= LK_NOWAIT; 3486 3487 error = BUF_TIMELOCK(bp, lockflags, 3488 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo); 3489 3490 /* 3491 * If we slept and got the lock we have to restart in case 3492 * the buffer changed identities. 3493 */ 3494 if (error == ENOLCK) 3495 goto loop; 3496 /* We timed out or were interrupted. */ 3497 else if (error) 3498 return (NULL); 3499 /* If recursed, assume caller knows the rules. */ 3500 else if (BUF_LOCKRECURSED(bp)) 3501 goto end; 3502 3503 /* 3504 * The buffer is locked. B_CACHE is cleared if the buffer is 3505 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 3506 * and for a VMIO buffer B_CACHE is adjusted according to the 3507 * backing VM cache. 3508 */ 3509 if (bp->b_flags & B_INVAL) 3510 bp->b_flags &= ~B_CACHE; 3511 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 3512 bp->b_flags |= B_CACHE; 3513 if (bp->b_flags & B_MANAGED) 3514 MPASS(bp->b_qindex == QUEUE_NONE); 3515 else 3516 bremfree(bp); 3517 3518 /* 3519 * check for size inconsistencies for non-VMIO case. 3520 */ 3521 if (bp->b_bcount != size) { 3522 if ((bp->b_flags & B_VMIO) == 0 || 3523 (size > bp->b_kvasize)) { 3524 if (bp->b_flags & B_DELWRI) { 3525 /* 3526 * If buffer is pinned and caller does 3527 * not want sleep waiting for it to be 3528 * unpinned, bail out 3529 * */ 3530 if (bp->b_pin_count > 0) { 3531 if (flags & GB_LOCK_NOWAIT) { 3532 bqrelse(bp); 3533 return (NULL); 3534 } else { 3535 bunpin_wait(bp); 3536 } 3537 } 3538 bp->b_flags |= B_NOCACHE; 3539 bwrite(bp); 3540 } else { 3541 if (LIST_EMPTY(&bp->b_dep)) { 3542 bp->b_flags |= B_RELBUF; 3543 brelse(bp); 3544 } else { 3545 bp->b_flags |= B_NOCACHE; 3546 bwrite(bp); 3547 } 3548 } 3549 goto loop; 3550 } 3551 } 3552 3553 /* 3554 * Handle the case of unmapped buffer which should 3555 * become mapped, or the buffer for which KVA 3556 * reservation is requested. 3557 */ 3558 bp_unmapped_get_kva(bp, blkno, size, flags); 3559 3560 /* 3561 * If the size is inconsistant in the VMIO case, we can resize 3562 * the buffer. This might lead to B_CACHE getting set or 3563 * cleared. If the size has not changed, B_CACHE remains 3564 * unchanged from its previous state. 3565 */ 3566 allocbuf(bp, size); 3567 3568 KASSERT(bp->b_offset != NOOFFSET, 3569 ("getblk: no buffer offset")); 3570 3571 /* 3572 * A buffer with B_DELWRI set and B_CACHE clear must 3573 * be committed before we can return the buffer in 3574 * order to prevent the caller from issuing a read 3575 * ( due to B_CACHE not being set ) and overwriting 3576 * it. 3577 * 3578 * Most callers, including NFS and FFS, need this to 3579 * operate properly either because they assume they 3580 * can issue a read if B_CACHE is not set, or because 3581 * ( for example ) an uncached B_DELWRI might loop due 3582 * to softupdates re-dirtying the buffer. In the latter 3583 * case, B_CACHE is set after the first write completes, 3584 * preventing further loops. 3585 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 3586 * above while extending the buffer, we cannot allow the 3587 * buffer to remain with B_CACHE set after the write 3588 * completes or it will represent a corrupt state. To 3589 * deal with this we set B_NOCACHE to scrap the buffer 3590 * after the write. 3591 * 3592 * We might be able to do something fancy, like setting 3593 * B_CACHE in bwrite() except if B_DELWRI is already set, 3594 * so the below call doesn't set B_CACHE, but that gets real 3595 * confusing. This is much easier. 3596 */ 3597 3598 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 3599 bp->b_flags |= B_NOCACHE; 3600 bwrite(bp); 3601 goto loop; 3602 } 3603 bp->b_flags &= ~B_DONE; 3604 } else { 3605 /* 3606 * Buffer is not in-core, create new buffer. The buffer 3607 * returned by getnewbuf() is locked. Note that the returned 3608 * buffer is also considered valid (not marked B_INVAL). 3609 */ 3610 BO_RUNLOCK(bo); 3611 /* 3612 * If the user does not want us to create the buffer, bail out 3613 * here. 3614 */ 3615 if (flags & GB_NOCREAT) 3616 return NULL; 3617 if (numfreebuffers == 0 && TD_IS_IDLETHREAD(curthread)) 3618 return NULL; 3619 3620 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize; 3621 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3622 offset = blkno * bsize; 3623 vmio = vp->v_object != NULL; 3624 if (vmio) { 3625 maxsize = size + (offset & PAGE_MASK); 3626 } else { 3627 maxsize = size; 3628 /* Do not allow non-VMIO notmapped buffers. */ 3629 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3630 } 3631 maxsize = imax(maxsize, bsize); 3632 3633 bp = getnewbuf(vp, slpflag, slptimeo, maxsize, flags); 3634 if (bp == NULL) { 3635 if (slpflag || slptimeo) 3636 return NULL; 3637 /* 3638 * XXX This is here until the sleep path is diagnosed 3639 * enough to work under very low memory conditions. 3640 * 3641 * There's an issue on low memory, 4BSD+non-preempt 3642 * systems (eg MIPS routers with 32MB RAM) where buffer 3643 * exhaustion occurs without sleeping for buffer 3644 * reclaimation. This just sticks in a loop and 3645 * constantly attempts to allocate a buffer, which 3646 * hits exhaustion and tries to wakeup bufdaemon. 3647 * This never happens because we never yield. 3648 * 3649 * The real solution is to identify and fix these cases 3650 * so we aren't effectively busy-waiting in a loop 3651 * until the reclaimation path has cycles to run. 3652 */ 3653 kern_yield(PRI_USER); 3654 goto loop; 3655 } 3656 3657 /* 3658 * This code is used to make sure that a buffer is not 3659 * created while the getnewbuf routine is blocked. 3660 * This can be a problem whether the vnode is locked or not. 3661 * If the buffer is created out from under us, we have to 3662 * throw away the one we just created. 3663 * 3664 * Note: this must occur before we associate the buffer 3665 * with the vp especially considering limitations in 3666 * the splay tree implementation when dealing with duplicate 3667 * lblkno's. 3668 */ 3669 BO_LOCK(bo); 3670 if (gbincore(bo, blkno)) { 3671 BO_UNLOCK(bo); 3672 bp->b_flags |= B_INVAL; 3673 brelse(bp); 3674 bufspace_release(maxsize); 3675 goto loop; 3676 } 3677 3678 /* 3679 * Insert the buffer into the hash, so that it can 3680 * be found by incore. 3681 */ 3682 bp->b_blkno = bp->b_lblkno = blkno; 3683 bp->b_offset = offset; 3684 bgetvp(vp, bp); 3685 BO_UNLOCK(bo); 3686 3687 /* 3688 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 3689 * buffer size starts out as 0, B_CACHE will be set by 3690 * allocbuf() for the VMIO case prior to it testing the 3691 * backing store for validity. 3692 */ 3693 3694 if (vmio) { 3695 bp->b_flags |= B_VMIO; 3696 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 3697 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 3698 bp, vp->v_object, bp->b_bufobj->bo_object)); 3699 } else { 3700 bp->b_flags &= ~B_VMIO; 3701 KASSERT(bp->b_bufobj->bo_object == NULL, 3702 ("ARGH! has b_bufobj->bo_object %p %p\n", 3703 bp, bp->b_bufobj->bo_object)); 3704 BUF_CHECK_MAPPED(bp); 3705 } 3706 3707 allocbuf(bp, size); 3708 bufspace_release(maxsize); 3709 bp->b_flags &= ~B_DONE; 3710 } 3711 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 3712 BUF_ASSERT_HELD(bp); 3713 end: 3714 KASSERT(bp->b_bufobj == bo, 3715 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 3716 return (bp); 3717 } 3718 3719 /* 3720 * Get an empty, disassociated buffer of given size. The buffer is initially 3721 * set to B_INVAL. 3722 */ 3723 struct buf * 3724 geteblk(int size, int flags) 3725 { 3726 struct buf *bp; 3727 int maxsize; 3728 3729 maxsize = (size + BKVAMASK) & ~BKVAMASK; 3730 while ((bp = getnewbuf(NULL, 0, 0, maxsize, flags)) == NULL) { 3731 if ((flags & GB_NOWAIT_BD) && 3732 (curthread->td_pflags & TDP_BUFNEED) != 0) 3733 return (NULL); 3734 } 3735 allocbuf(bp, size); 3736 bufspace_release(maxsize); 3737 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 3738 BUF_ASSERT_HELD(bp); 3739 return (bp); 3740 } 3741 3742 /* 3743 * Truncate the backing store for a non-vmio buffer. 3744 */ 3745 static void 3746 vfs_nonvmio_truncate(struct buf *bp, int newbsize) 3747 { 3748 3749 if (bp->b_flags & B_MALLOC) { 3750 /* 3751 * malloced buffers are not shrunk 3752 */ 3753 if (newbsize == 0) { 3754 bufmallocadjust(bp, 0); 3755 free(bp->b_data, M_BIOBUF); 3756 bp->b_data = bp->b_kvabase; 3757 bp->b_flags &= ~B_MALLOC; 3758 } 3759 return; 3760 } 3761 vm_hold_free_pages(bp, newbsize); 3762 bufspace_adjust(bp, newbsize); 3763 } 3764 3765 /* 3766 * Extend the backing for a non-VMIO buffer. 3767 */ 3768 static void 3769 vfs_nonvmio_extend(struct buf *bp, int newbsize) 3770 { 3771 caddr_t origbuf; 3772 int origbufsize; 3773 3774 /* 3775 * We only use malloced memory on the first allocation. 3776 * and revert to page-allocated memory when the buffer 3777 * grows. 3778 * 3779 * There is a potential smp race here that could lead 3780 * to bufmallocspace slightly passing the max. It 3781 * is probably extremely rare and not worth worrying 3782 * over. 3783 */ 3784 if (bp->b_bufsize == 0 && newbsize <= PAGE_SIZE/2 && 3785 bufmallocspace < maxbufmallocspace) { 3786 bp->b_data = malloc(newbsize, M_BIOBUF, M_WAITOK); 3787 bp->b_flags |= B_MALLOC; 3788 bufmallocadjust(bp, newbsize); 3789 return; 3790 } 3791 3792 /* 3793 * If the buffer is growing on its other-than-first 3794 * allocation then we revert to the page-allocation 3795 * scheme. 3796 */ 3797 origbuf = NULL; 3798 origbufsize = 0; 3799 if (bp->b_flags & B_MALLOC) { 3800 origbuf = bp->b_data; 3801 origbufsize = bp->b_bufsize; 3802 bp->b_data = bp->b_kvabase; 3803 bufmallocadjust(bp, 0); 3804 bp->b_flags &= ~B_MALLOC; 3805 newbsize = round_page(newbsize); 3806 } 3807 vm_hold_load_pages(bp, (vm_offset_t) bp->b_data + bp->b_bufsize, 3808 (vm_offset_t) bp->b_data + newbsize); 3809 if (origbuf != NULL) { 3810 bcopy(origbuf, bp->b_data, origbufsize); 3811 free(origbuf, M_BIOBUF); 3812 } 3813 bufspace_adjust(bp, newbsize); 3814 } 3815 3816 /* 3817 * This code constitutes the buffer memory from either anonymous system 3818 * memory (in the case of non-VMIO operations) or from an associated 3819 * VM object (in the case of VMIO operations). This code is able to 3820 * resize a buffer up or down. 3821 * 3822 * Note that this code is tricky, and has many complications to resolve 3823 * deadlock or inconsistant data situations. Tread lightly!!! 3824 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 3825 * the caller. Calling this code willy nilly can result in the loss of data. 3826 * 3827 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 3828 * B_CACHE for the non-VMIO case. 3829 */ 3830 int 3831 allocbuf(struct buf *bp, int size) 3832 { 3833 int newbsize; 3834 3835 BUF_ASSERT_HELD(bp); 3836 3837 if (bp->b_bcount == size) 3838 return (1); 3839 3840 if (bp->b_kvasize != 0 && bp->b_kvasize < size) 3841 panic("allocbuf: buffer too small"); 3842 3843 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3844 if ((bp->b_flags & B_VMIO) == 0) { 3845 if ((bp->b_flags & B_MALLOC) == 0) 3846 newbsize = round_page(newbsize); 3847 /* 3848 * Just get anonymous memory from the kernel. Don't 3849 * mess with B_CACHE. 3850 */ 3851 if (newbsize < bp->b_bufsize) 3852 vfs_nonvmio_truncate(bp, newbsize); 3853 else if (newbsize > bp->b_bufsize) 3854 vfs_nonvmio_extend(bp, newbsize); 3855 } else { 3856 int desiredpages; 3857 3858 desiredpages = (size == 0) ? 0 : 3859 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 3860 3861 if (bp->b_flags & B_MALLOC) 3862 panic("allocbuf: VMIO buffer can't be malloced"); 3863 /* 3864 * Set B_CACHE initially if buffer is 0 length or will become 3865 * 0-length. 3866 */ 3867 if (size == 0 || bp->b_bufsize == 0) 3868 bp->b_flags |= B_CACHE; 3869 3870 if (newbsize < bp->b_bufsize) 3871 vfs_vmio_truncate(bp, desiredpages); 3872 /* XXX This looks as if it should be newbsize > b_bufsize */ 3873 else if (size > bp->b_bcount) 3874 vfs_vmio_extend(bp, desiredpages, size); 3875 bufspace_adjust(bp, newbsize); 3876 } 3877 bp->b_bcount = size; /* requested buffer size. */ 3878 return (1); 3879 } 3880 3881 extern int inflight_transient_maps; 3882 3883 void 3884 biodone(struct bio *bp) 3885 { 3886 struct mtx *mtxp; 3887 void (*done)(struct bio *); 3888 vm_offset_t start, end; 3889 3890 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) { 3891 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING; 3892 bp->bio_flags |= BIO_UNMAPPED; 3893 start = trunc_page((vm_offset_t)bp->bio_data); 3894 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length); 3895 bp->bio_data = unmapped_buf; 3896 pmap_qremove(start, OFF_TO_IDX(end - start)); 3897 vmem_free(transient_arena, start, end - start); 3898 atomic_add_int(&inflight_transient_maps, -1); 3899 } 3900 done = bp->bio_done; 3901 if (done == NULL) { 3902 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3903 mtx_lock(mtxp); 3904 bp->bio_flags |= BIO_DONE; 3905 wakeup(bp); 3906 mtx_unlock(mtxp); 3907 } else { 3908 bp->bio_flags |= BIO_DONE; 3909 done(bp); 3910 } 3911 } 3912 3913 /* 3914 * Wait for a BIO to finish. 3915 */ 3916 int 3917 biowait(struct bio *bp, const char *wchan) 3918 { 3919 struct mtx *mtxp; 3920 3921 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3922 mtx_lock(mtxp); 3923 while ((bp->bio_flags & BIO_DONE) == 0) 3924 msleep(bp, mtxp, PRIBIO, wchan, 0); 3925 mtx_unlock(mtxp); 3926 if (bp->bio_error != 0) 3927 return (bp->bio_error); 3928 if (!(bp->bio_flags & BIO_ERROR)) 3929 return (0); 3930 return (EIO); 3931 } 3932 3933 void 3934 biofinish(struct bio *bp, struct devstat *stat, int error) 3935 { 3936 3937 if (error) { 3938 bp->bio_error = error; 3939 bp->bio_flags |= BIO_ERROR; 3940 } 3941 if (stat != NULL) 3942 devstat_end_transaction_bio(stat, bp); 3943 biodone(bp); 3944 } 3945 3946 /* 3947 * bufwait: 3948 * 3949 * Wait for buffer I/O completion, returning error status. The buffer 3950 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3951 * error and cleared. 3952 */ 3953 int 3954 bufwait(struct buf *bp) 3955 { 3956 if (bp->b_iocmd == BIO_READ) 3957 bwait(bp, PRIBIO, "biord"); 3958 else 3959 bwait(bp, PRIBIO, "biowr"); 3960 if (bp->b_flags & B_EINTR) { 3961 bp->b_flags &= ~B_EINTR; 3962 return (EINTR); 3963 } 3964 if (bp->b_ioflags & BIO_ERROR) { 3965 return (bp->b_error ? bp->b_error : EIO); 3966 } else { 3967 return (0); 3968 } 3969 } 3970 3971 /* 3972 * bufdone: 3973 * 3974 * Finish I/O on a buffer, optionally calling a completion function. 3975 * This is usually called from an interrupt so process blocking is 3976 * not allowed. 3977 * 3978 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3979 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3980 * assuming B_INVAL is clear. 3981 * 3982 * For the VMIO case, we set B_CACHE if the op was a read and no 3983 * read error occured, or if the op was a write. B_CACHE is never 3984 * set if the buffer is invalid or otherwise uncacheable. 3985 * 3986 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3987 * initiator to leave B_INVAL set to brelse the buffer out of existance 3988 * in the biodone routine. 3989 */ 3990 void 3991 bufdone(struct buf *bp) 3992 { 3993 struct bufobj *dropobj; 3994 void (*biodone)(struct buf *); 3995 3996 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 3997 dropobj = NULL; 3998 3999 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 4000 BUF_ASSERT_HELD(bp); 4001 4002 runningbufwakeup(bp); 4003 if (bp->b_iocmd == BIO_WRITE) 4004 dropobj = bp->b_bufobj; 4005 /* call optional completion function if requested */ 4006 if (bp->b_iodone != NULL) { 4007 biodone = bp->b_iodone; 4008 bp->b_iodone = NULL; 4009 (*biodone) (bp); 4010 if (dropobj) 4011 bufobj_wdrop(dropobj); 4012 return; 4013 } 4014 4015 bufdone_finish(bp); 4016 4017 if (dropobj) 4018 bufobj_wdrop(dropobj); 4019 } 4020 4021 void 4022 bufdone_finish(struct buf *bp) 4023 { 4024 BUF_ASSERT_HELD(bp); 4025 4026 if (!LIST_EMPTY(&bp->b_dep)) 4027 buf_complete(bp); 4028 4029 if (bp->b_flags & B_VMIO) { 4030 /* 4031 * Set B_CACHE if the op was a normal read and no error 4032 * occured. B_CACHE is set for writes in the b*write() 4033 * routines. 4034 */ 4035 if (bp->b_iocmd == BIO_READ && 4036 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 4037 !(bp->b_ioflags & BIO_ERROR)) 4038 bp->b_flags |= B_CACHE; 4039 vfs_vmio_iodone(bp); 4040 } 4041 4042 /* 4043 * For asynchronous completions, release the buffer now. The brelse 4044 * will do a wakeup there if necessary - so no need to do a wakeup 4045 * here in the async case. The sync case always needs to do a wakeup. 4046 */ 4047 if (bp->b_flags & B_ASYNC) { 4048 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || 4049 (bp->b_ioflags & BIO_ERROR)) 4050 brelse(bp); 4051 else 4052 bqrelse(bp); 4053 } else 4054 bdone(bp); 4055 } 4056 4057 /* 4058 * This routine is called in lieu of iodone in the case of 4059 * incomplete I/O. This keeps the busy status for pages 4060 * consistant. 4061 */ 4062 void 4063 vfs_unbusy_pages(struct buf *bp) 4064 { 4065 int i; 4066 vm_object_t obj; 4067 vm_page_t m; 4068 4069 runningbufwakeup(bp); 4070 if (!(bp->b_flags & B_VMIO)) 4071 return; 4072 4073 obj = bp->b_bufobj->bo_object; 4074 VM_OBJECT_WLOCK(obj); 4075 for (i = 0; i < bp->b_npages; i++) { 4076 m = bp->b_pages[i]; 4077 if (m == bogus_page) { 4078 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 4079 if (!m) 4080 panic("vfs_unbusy_pages: page missing\n"); 4081 bp->b_pages[i] = m; 4082 if (buf_mapped(bp)) { 4083 BUF_CHECK_MAPPED(bp); 4084 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4085 bp->b_pages, bp->b_npages); 4086 } else 4087 BUF_CHECK_UNMAPPED(bp); 4088 } 4089 vm_page_sunbusy(m); 4090 } 4091 vm_object_pip_wakeupn(obj, bp->b_npages); 4092 VM_OBJECT_WUNLOCK(obj); 4093 } 4094 4095 /* 4096 * vfs_page_set_valid: 4097 * 4098 * Set the valid bits in a page based on the supplied offset. The 4099 * range is restricted to the buffer's size. 4100 * 4101 * This routine is typically called after a read completes. 4102 */ 4103 static void 4104 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4105 { 4106 vm_ooffset_t eoff; 4107 4108 /* 4109 * Compute the end offset, eoff, such that [off, eoff) does not span a 4110 * page boundary and eoff is not greater than the end of the buffer. 4111 * The end of the buffer, in this case, is our file EOF, not the 4112 * allocation size of the buffer. 4113 */ 4114 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 4115 if (eoff > bp->b_offset + bp->b_bcount) 4116 eoff = bp->b_offset + bp->b_bcount; 4117 4118 /* 4119 * Set valid range. This is typically the entire buffer and thus the 4120 * entire page. 4121 */ 4122 if (eoff > off) 4123 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off); 4124 } 4125 4126 /* 4127 * vfs_page_set_validclean: 4128 * 4129 * Set the valid bits and clear the dirty bits in a page based on the 4130 * supplied offset. The range is restricted to the buffer's size. 4131 */ 4132 static void 4133 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4134 { 4135 vm_ooffset_t soff, eoff; 4136 4137 /* 4138 * Start and end offsets in buffer. eoff - soff may not cross a 4139 * page boundry or cross the end of the buffer. The end of the 4140 * buffer, in this case, is our file EOF, not the allocation size 4141 * of the buffer. 4142 */ 4143 soff = off; 4144 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4145 if (eoff > bp->b_offset + bp->b_bcount) 4146 eoff = bp->b_offset + bp->b_bcount; 4147 4148 /* 4149 * Set valid range. This is typically the entire buffer and thus the 4150 * entire page. 4151 */ 4152 if (eoff > soff) { 4153 vm_page_set_validclean( 4154 m, 4155 (vm_offset_t) (soff & PAGE_MASK), 4156 (vm_offset_t) (eoff - soff) 4157 ); 4158 } 4159 } 4160 4161 /* 4162 * Ensure that all buffer pages are not exclusive busied. If any page is 4163 * exclusive busy, drain it. 4164 */ 4165 void 4166 vfs_drain_busy_pages(struct buf *bp) 4167 { 4168 vm_page_t m; 4169 int i, last_busied; 4170 4171 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object); 4172 last_busied = 0; 4173 for (i = 0; i < bp->b_npages; i++) { 4174 m = bp->b_pages[i]; 4175 if (vm_page_xbusied(m)) { 4176 for (; last_busied < i; last_busied++) 4177 vm_page_sbusy(bp->b_pages[last_busied]); 4178 while (vm_page_xbusied(m)) { 4179 vm_page_lock(m); 4180 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4181 vm_page_busy_sleep(m, "vbpage"); 4182 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4183 } 4184 } 4185 } 4186 for (i = 0; i < last_busied; i++) 4187 vm_page_sunbusy(bp->b_pages[i]); 4188 } 4189 4190 /* 4191 * This routine is called before a device strategy routine. 4192 * It is used to tell the VM system that paging I/O is in 4193 * progress, and treat the pages associated with the buffer 4194 * almost as being exclusive busy. Also the object paging_in_progress 4195 * flag is handled to make sure that the object doesn't become 4196 * inconsistant. 4197 * 4198 * Since I/O has not been initiated yet, certain buffer flags 4199 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 4200 * and should be ignored. 4201 */ 4202 void 4203 vfs_busy_pages(struct buf *bp, int clear_modify) 4204 { 4205 int i, bogus; 4206 vm_object_t obj; 4207 vm_ooffset_t foff; 4208 vm_page_t m; 4209 4210 if (!(bp->b_flags & B_VMIO)) 4211 return; 4212 4213 obj = bp->b_bufobj->bo_object; 4214 foff = bp->b_offset; 4215 KASSERT(bp->b_offset != NOOFFSET, 4216 ("vfs_busy_pages: no buffer offset")); 4217 VM_OBJECT_WLOCK(obj); 4218 vfs_drain_busy_pages(bp); 4219 if (bp->b_bufsize != 0) 4220 vfs_setdirty_locked_object(bp); 4221 bogus = 0; 4222 for (i = 0; i < bp->b_npages; i++) { 4223 m = bp->b_pages[i]; 4224 4225 if ((bp->b_flags & B_CLUSTER) == 0) { 4226 vm_object_pip_add(obj, 1); 4227 vm_page_sbusy(m); 4228 } 4229 /* 4230 * When readying a buffer for a read ( i.e 4231 * clear_modify == 0 ), it is important to do 4232 * bogus_page replacement for valid pages in 4233 * partially instantiated buffers. Partially 4234 * instantiated buffers can, in turn, occur when 4235 * reconstituting a buffer from its VM backing store 4236 * base. We only have to do this if B_CACHE is 4237 * clear ( which causes the I/O to occur in the 4238 * first place ). The replacement prevents the read 4239 * I/O from overwriting potentially dirty VM-backed 4240 * pages. XXX bogus page replacement is, uh, bogus. 4241 * It may not work properly with small-block devices. 4242 * We need to find a better way. 4243 */ 4244 if (clear_modify) { 4245 pmap_remove_write(m); 4246 vfs_page_set_validclean(bp, foff, m); 4247 } else if (m->valid == VM_PAGE_BITS_ALL && 4248 (bp->b_flags & B_CACHE) == 0) { 4249 bp->b_pages[i] = bogus_page; 4250 bogus++; 4251 } 4252 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4253 } 4254 VM_OBJECT_WUNLOCK(obj); 4255 if (bogus && buf_mapped(bp)) { 4256 BUF_CHECK_MAPPED(bp); 4257 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4258 bp->b_pages, bp->b_npages); 4259 } 4260 } 4261 4262 /* 4263 * vfs_bio_set_valid: 4264 * 4265 * Set the range within the buffer to valid. The range is 4266 * relative to the beginning of the buffer, b_offset. Note that 4267 * b_offset itself may be offset from the beginning of the first 4268 * page. 4269 */ 4270 void 4271 vfs_bio_set_valid(struct buf *bp, int base, int size) 4272 { 4273 int i, n; 4274 vm_page_t m; 4275 4276 if (!(bp->b_flags & B_VMIO)) 4277 return; 4278 4279 /* 4280 * Fixup base to be relative to beginning of first page. 4281 * Set initial n to be the maximum number of bytes in the 4282 * first page that can be validated. 4283 */ 4284 base += (bp->b_offset & PAGE_MASK); 4285 n = PAGE_SIZE - (base & PAGE_MASK); 4286 4287 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4288 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4289 m = bp->b_pages[i]; 4290 if (n > size) 4291 n = size; 4292 vm_page_set_valid_range(m, base & PAGE_MASK, n); 4293 base += n; 4294 size -= n; 4295 n = PAGE_SIZE; 4296 } 4297 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4298 } 4299 4300 /* 4301 * vfs_bio_clrbuf: 4302 * 4303 * If the specified buffer is a non-VMIO buffer, clear the entire 4304 * buffer. If the specified buffer is a VMIO buffer, clear and 4305 * validate only the previously invalid portions of the buffer. 4306 * This routine essentially fakes an I/O, so we need to clear 4307 * BIO_ERROR and B_INVAL. 4308 * 4309 * Note that while we only theoretically need to clear through b_bcount, 4310 * we go ahead and clear through b_bufsize. 4311 */ 4312 void 4313 vfs_bio_clrbuf(struct buf *bp) 4314 { 4315 int i, j, mask, sa, ea, slide; 4316 4317 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 4318 clrbuf(bp); 4319 return; 4320 } 4321 bp->b_flags &= ~B_INVAL; 4322 bp->b_ioflags &= ~BIO_ERROR; 4323 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4324 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 4325 (bp->b_offset & PAGE_MASK) == 0) { 4326 if (bp->b_pages[0] == bogus_page) 4327 goto unlock; 4328 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 4329 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object); 4330 if ((bp->b_pages[0]->valid & mask) == mask) 4331 goto unlock; 4332 if ((bp->b_pages[0]->valid & mask) == 0) { 4333 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize); 4334 bp->b_pages[0]->valid |= mask; 4335 goto unlock; 4336 } 4337 } 4338 sa = bp->b_offset & PAGE_MASK; 4339 slide = 0; 4340 for (i = 0; i < bp->b_npages; i++, sa = 0) { 4341 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize); 4342 ea = slide & PAGE_MASK; 4343 if (ea == 0) 4344 ea = PAGE_SIZE; 4345 if (bp->b_pages[i] == bogus_page) 4346 continue; 4347 j = sa / DEV_BSIZE; 4348 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 4349 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object); 4350 if ((bp->b_pages[i]->valid & mask) == mask) 4351 continue; 4352 if ((bp->b_pages[i]->valid & mask) == 0) 4353 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa); 4354 else { 4355 for (; sa < ea; sa += DEV_BSIZE, j++) { 4356 if ((bp->b_pages[i]->valid & (1 << j)) == 0) { 4357 pmap_zero_page_area(bp->b_pages[i], 4358 sa, DEV_BSIZE); 4359 } 4360 } 4361 } 4362 bp->b_pages[i]->valid |= mask; 4363 } 4364 unlock: 4365 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4366 bp->b_resid = 0; 4367 } 4368 4369 void 4370 vfs_bio_bzero_buf(struct buf *bp, int base, int size) 4371 { 4372 vm_page_t m; 4373 int i, n; 4374 4375 if (buf_mapped(bp)) { 4376 BUF_CHECK_MAPPED(bp); 4377 bzero(bp->b_data + base, size); 4378 } else { 4379 BUF_CHECK_UNMAPPED(bp); 4380 n = PAGE_SIZE - (base & PAGE_MASK); 4381 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4382 m = bp->b_pages[i]; 4383 if (n > size) 4384 n = size; 4385 pmap_zero_page_area(m, base & PAGE_MASK, n); 4386 base += n; 4387 size -= n; 4388 n = PAGE_SIZE; 4389 } 4390 } 4391 } 4392 4393 /* 4394 * vm_hold_load_pages and vm_hold_free_pages get pages into 4395 * a buffers address space. The pages are anonymous and are 4396 * not associated with a file object. 4397 */ 4398 static void 4399 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4400 { 4401 vm_offset_t pg; 4402 vm_page_t p; 4403 int index; 4404 4405 BUF_CHECK_MAPPED(bp); 4406 4407 to = round_page(to); 4408 from = round_page(from); 4409 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4410 4411 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 4412 tryagain: 4413 /* 4414 * note: must allocate system pages since blocking here 4415 * could interfere with paging I/O, no matter which 4416 * process we are. 4417 */ 4418 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ | 4419 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT)); 4420 if (p == NULL) { 4421 VM_WAIT; 4422 goto tryagain; 4423 } 4424 pmap_qenter(pg, &p, 1); 4425 bp->b_pages[index] = p; 4426 } 4427 bp->b_npages = index; 4428 } 4429 4430 /* Return pages associated with this buf to the vm system */ 4431 static void 4432 vm_hold_free_pages(struct buf *bp, int newbsize) 4433 { 4434 vm_offset_t from; 4435 vm_page_t p; 4436 int index, newnpages; 4437 4438 BUF_CHECK_MAPPED(bp); 4439 4440 from = round_page((vm_offset_t)bp->b_data + newbsize); 4441 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4442 if (bp->b_npages > newnpages) 4443 pmap_qremove(from, bp->b_npages - newnpages); 4444 for (index = newnpages; index < bp->b_npages; index++) { 4445 p = bp->b_pages[index]; 4446 bp->b_pages[index] = NULL; 4447 if (vm_page_sbusied(p)) 4448 printf("vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 4449 (intmax_t)bp->b_blkno, (intmax_t)bp->b_lblkno); 4450 p->wire_count--; 4451 vm_page_free(p); 4452 atomic_subtract_int(&vm_cnt.v_wire_count, 1); 4453 } 4454 bp->b_npages = newnpages; 4455 } 4456 4457 /* 4458 * Map an IO request into kernel virtual address space. 4459 * 4460 * All requests are (re)mapped into kernel VA space. 4461 * Notice that we use b_bufsize for the size of the buffer 4462 * to be mapped. b_bcount might be modified by the driver. 4463 * 4464 * Note that even if the caller determines that the address space should 4465 * be valid, a race or a smaller-file mapped into a larger space may 4466 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 4467 * check the return value. 4468 * 4469 * This function only works with pager buffers. 4470 */ 4471 int 4472 vmapbuf(struct buf *bp, int mapbuf) 4473 { 4474 vm_prot_t prot; 4475 int pidx; 4476 4477 if (bp->b_bufsize < 0) 4478 return (-1); 4479 prot = VM_PROT_READ; 4480 if (bp->b_iocmd == BIO_READ) 4481 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 4482 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 4483 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages, 4484 btoc(MAXPHYS))) < 0) 4485 return (-1); 4486 bp->b_npages = pidx; 4487 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK; 4488 if (mapbuf || !unmapped_buf_allowed) { 4489 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_pages, pidx); 4490 bp->b_data = bp->b_kvabase + bp->b_offset; 4491 } else 4492 bp->b_data = unmapped_buf; 4493 return(0); 4494 } 4495 4496 /* 4497 * Free the io map PTEs associated with this IO operation. 4498 * We also invalidate the TLB entries and restore the original b_addr. 4499 * 4500 * This function only works with pager buffers. 4501 */ 4502 void 4503 vunmapbuf(struct buf *bp) 4504 { 4505 int npages; 4506 4507 npages = bp->b_npages; 4508 if (buf_mapped(bp)) 4509 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 4510 vm_page_unhold_pages(bp->b_pages, npages); 4511 4512 bp->b_data = unmapped_buf; 4513 } 4514 4515 void 4516 bdone(struct buf *bp) 4517 { 4518 struct mtx *mtxp; 4519 4520 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4521 mtx_lock(mtxp); 4522 bp->b_flags |= B_DONE; 4523 wakeup(bp); 4524 mtx_unlock(mtxp); 4525 } 4526 4527 void 4528 bwait(struct buf *bp, u_char pri, const char *wchan) 4529 { 4530 struct mtx *mtxp; 4531 4532 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4533 mtx_lock(mtxp); 4534 while ((bp->b_flags & B_DONE) == 0) 4535 msleep(bp, mtxp, pri, wchan, 0); 4536 mtx_unlock(mtxp); 4537 } 4538 4539 int 4540 bufsync(struct bufobj *bo, int waitfor) 4541 { 4542 4543 return (VOP_FSYNC(bo->__bo_vnode, waitfor, curthread)); 4544 } 4545 4546 void 4547 bufstrategy(struct bufobj *bo, struct buf *bp) 4548 { 4549 int i = 0; 4550 struct vnode *vp; 4551 4552 vp = bp->b_vp; 4553 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 4554 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 4555 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 4556 i = VOP_STRATEGY(vp, bp); 4557 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 4558 } 4559 4560 void 4561 bufobj_wrefl(struct bufobj *bo) 4562 { 4563 4564 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4565 ASSERT_BO_WLOCKED(bo); 4566 bo->bo_numoutput++; 4567 } 4568 4569 void 4570 bufobj_wref(struct bufobj *bo) 4571 { 4572 4573 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4574 BO_LOCK(bo); 4575 bo->bo_numoutput++; 4576 BO_UNLOCK(bo); 4577 } 4578 4579 void 4580 bufobj_wdrop(struct bufobj *bo) 4581 { 4582 4583 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 4584 BO_LOCK(bo); 4585 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 4586 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 4587 bo->bo_flag &= ~BO_WWAIT; 4588 wakeup(&bo->bo_numoutput); 4589 } 4590 BO_UNLOCK(bo); 4591 } 4592 4593 int 4594 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 4595 { 4596 int error; 4597 4598 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 4599 ASSERT_BO_WLOCKED(bo); 4600 error = 0; 4601 while (bo->bo_numoutput) { 4602 bo->bo_flag |= BO_WWAIT; 4603 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo), 4604 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 4605 if (error) 4606 break; 4607 } 4608 return (error); 4609 } 4610 4611 void 4612 bpin(struct buf *bp) 4613 { 4614 struct mtx *mtxp; 4615 4616 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4617 mtx_lock(mtxp); 4618 bp->b_pin_count++; 4619 mtx_unlock(mtxp); 4620 } 4621 4622 void 4623 bunpin(struct buf *bp) 4624 { 4625 struct mtx *mtxp; 4626 4627 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4628 mtx_lock(mtxp); 4629 if (--bp->b_pin_count == 0) 4630 wakeup(bp); 4631 mtx_unlock(mtxp); 4632 } 4633 4634 void 4635 bunpin_wait(struct buf *bp) 4636 { 4637 struct mtx *mtxp; 4638 4639 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4640 mtx_lock(mtxp); 4641 while (bp->b_pin_count > 0) 4642 msleep(bp, mtxp, PRIBIO, "bwunpin", 0); 4643 mtx_unlock(mtxp); 4644 } 4645 4646 /* 4647 * Set bio_data or bio_ma for struct bio from the struct buf. 4648 */ 4649 void 4650 bdata2bio(struct buf *bp, struct bio *bip) 4651 { 4652 4653 if (!buf_mapped(bp)) { 4654 KASSERT(unmapped_buf_allowed, ("unmapped")); 4655 bip->bio_ma = bp->b_pages; 4656 bip->bio_ma_n = bp->b_npages; 4657 bip->bio_data = unmapped_buf; 4658 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 4659 bip->bio_flags |= BIO_UNMAPPED; 4660 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) / 4661 PAGE_SIZE == bp->b_npages, 4662 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset, 4663 (long long)bip->bio_length, bip->bio_ma_n)); 4664 } else { 4665 bip->bio_data = bp->b_data; 4666 bip->bio_ma = NULL; 4667 } 4668 } 4669 4670 #include "opt_ddb.h" 4671 #ifdef DDB 4672 #include <ddb/ddb.h> 4673 4674 /* DDB command to show buffer data */ 4675 DB_SHOW_COMMAND(buffer, db_show_buffer) 4676 { 4677 /* get args */ 4678 struct buf *bp = (struct buf *)addr; 4679 4680 if (!have_addr) { 4681 db_printf("usage: show buffer <addr>\n"); 4682 return; 4683 } 4684 4685 db_printf("buf at %p\n", bp); 4686 db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n", 4687 (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags, 4688 PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS); 4689 db_printf( 4690 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 4691 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, " 4692 "b_dep = %p\n", 4693 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 4694 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 4695 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first); 4696 db_printf("b_kvabase = %p, b_kvasize = %d\n", 4697 bp->b_kvabase, bp->b_kvasize); 4698 if (bp->b_npages) { 4699 int i; 4700 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 4701 for (i = 0; i < bp->b_npages; i++) { 4702 vm_page_t m; 4703 m = bp->b_pages[i]; 4704 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 4705 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 4706 if ((i + 1) < bp->b_npages) 4707 db_printf(","); 4708 } 4709 db_printf("\n"); 4710 } 4711 db_printf(" "); 4712 BUF_LOCKPRINTINFO(bp); 4713 } 4714 4715 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 4716 { 4717 struct buf *bp; 4718 int i; 4719 4720 for (i = 0; i < nbuf; i++) { 4721 bp = &buf[i]; 4722 if (BUF_ISLOCKED(bp)) { 4723 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4724 db_printf("\n"); 4725 } 4726 } 4727 } 4728 4729 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 4730 { 4731 struct vnode *vp; 4732 struct buf *bp; 4733 4734 if (!have_addr) { 4735 db_printf("usage: show vnodebufs <addr>\n"); 4736 return; 4737 } 4738 vp = (struct vnode *)addr; 4739 db_printf("Clean buffers:\n"); 4740 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 4741 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4742 db_printf("\n"); 4743 } 4744 db_printf("Dirty buffers:\n"); 4745 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 4746 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4747 db_printf("\n"); 4748 } 4749 } 4750 4751 DB_COMMAND(countfreebufs, db_coundfreebufs) 4752 { 4753 struct buf *bp; 4754 int i, used = 0, nfree = 0; 4755 4756 if (have_addr) { 4757 db_printf("usage: countfreebufs\n"); 4758 return; 4759 } 4760 4761 for (i = 0; i < nbuf; i++) { 4762 bp = &buf[i]; 4763 if (bp->b_qindex == QUEUE_EMPTY) 4764 nfree++; 4765 else 4766 used++; 4767 } 4768 4769 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 4770 nfree + used); 4771 db_printf("numfreebuffers is %d\n", numfreebuffers); 4772 } 4773 #endif /* DDB */ 4774