1 /*- 2 * Copyright (c) 2004 Poul-Henning Kamp 3 * Copyright (c) 1994,1997 John S. Dyson 4 * Copyright (c) 2013 The FreeBSD Foundation 5 * All rights reserved. 6 * 7 * Portions of this software were developed by Konstantin Belousov 8 * under sponsorship from the FreeBSD Foundation. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 /* 33 * this file contains a new buffer I/O scheme implementing a coherent 34 * VM object and buffer cache scheme. Pains have been taken to make 35 * sure that the performance degradation associated with schemes such 36 * as this is not realized. 37 * 38 * Author: John S. Dyson 39 * Significant help during the development and debugging phases 40 * had been provided by David Greenman, also of the FreeBSD core team. 41 * 42 * see man buf(9) for more info. 43 */ 44 45 #include <sys/cdefs.h> 46 __FBSDID("$FreeBSD$"); 47 48 #include <sys/param.h> 49 #include <sys/systm.h> 50 #include <sys/bio.h> 51 #include <sys/conf.h> 52 #include <sys/buf.h> 53 #include <sys/devicestat.h> 54 #include <sys/eventhandler.h> 55 #include <sys/fail.h> 56 #include <sys/limits.h> 57 #include <sys/lock.h> 58 #include <sys/malloc.h> 59 #include <sys/mount.h> 60 #include <sys/mutex.h> 61 #include <sys/kernel.h> 62 #include <sys/kthread.h> 63 #include <sys/proc.h> 64 #include <sys/racct.h> 65 #include <sys/resourcevar.h> 66 #include <sys/rwlock.h> 67 #include <sys/smp.h> 68 #include <sys/sysctl.h> 69 #include <sys/sysproto.h> 70 #include <sys/vmem.h> 71 #include <sys/vmmeter.h> 72 #include <sys/vnode.h> 73 #include <sys/watchdog.h> 74 #include <geom/geom.h> 75 #include <vm/vm.h> 76 #include <vm/vm_param.h> 77 #include <vm/vm_kern.h> 78 #include <vm/vm_object.h> 79 #include <vm/vm_page.h> 80 #include <vm/vm_pageout.h> 81 #include <vm/vm_pager.h> 82 #include <vm/vm_extern.h> 83 #include <vm/vm_map.h> 84 #include <vm/swap_pager.h> 85 #include "opt_compat.h" 86 #include "opt_swap.h" 87 88 static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer"); 89 90 struct bio_ops bioops; /* I/O operation notification */ 91 92 struct buf_ops buf_ops_bio = { 93 .bop_name = "buf_ops_bio", 94 .bop_write = bufwrite, 95 .bop_strategy = bufstrategy, 96 .bop_sync = bufsync, 97 .bop_bdflush = bufbdflush, 98 }; 99 100 static struct buf *buf; /* buffer header pool */ 101 extern struct buf *swbuf; /* Swap buffer header pool. */ 102 caddr_t unmapped_buf; 103 104 /* Used below and for softdep flushing threads in ufs/ffs/ffs_softdep.c */ 105 struct proc *bufdaemonproc; 106 struct proc *bufspacedaemonproc; 107 108 static int inmem(struct vnode *vp, daddr_t blkno); 109 static void vm_hold_free_pages(struct buf *bp, int newbsize); 110 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from, 111 vm_offset_t to); 112 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m); 113 static void vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, 114 vm_page_t m); 115 static void vfs_clean_pages_dirty_buf(struct buf *bp); 116 static void vfs_setdirty_locked_object(struct buf *bp); 117 static void vfs_vmio_invalidate(struct buf *bp); 118 static void vfs_vmio_truncate(struct buf *bp, int npages); 119 static void vfs_vmio_extend(struct buf *bp, int npages, int size); 120 static int vfs_bio_clcheck(struct vnode *vp, int size, 121 daddr_t lblkno, daddr_t blkno); 122 static int buf_flush(struct vnode *vp, int); 123 static int buf_recycle(bool); 124 static int buf_scan(bool); 125 static int flushbufqueues(struct vnode *, int, int); 126 static void buf_daemon(void); 127 static void bremfreel(struct buf *bp); 128 static __inline void bd_wakeup(void); 129 static int sysctl_runningspace(SYSCTL_HANDLER_ARGS); 130 static void bufkva_reclaim(vmem_t *, int); 131 static void bufkva_free(struct buf *); 132 static int buf_import(void *, void **, int, int); 133 static void buf_release(void *, void **, int); 134 135 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 136 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 137 static int sysctl_bufspace(SYSCTL_HANDLER_ARGS); 138 #endif 139 140 int vmiodirenable = TRUE; 141 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, 142 "Use the VM system for directory writes"); 143 long runningbufspace; 144 SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 145 "Amount of presently outstanding async buffer io"); 146 static long bufspace; 147 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 148 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 149 SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD, 150 &bufspace, 0, sysctl_bufspace, "L", "Virtual memory used for buffers"); 151 #else 152 SYSCTL_LONG(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, 153 "Physical memory used for buffers"); 154 #endif 155 static long bufkvaspace; 156 SYSCTL_LONG(_vfs, OID_AUTO, bufkvaspace, CTLFLAG_RD, &bufkvaspace, 0, 157 "Kernel virtual memory used for buffers"); 158 static long maxbufspace; 159 SYSCTL_LONG(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RW, &maxbufspace, 0, 160 "Maximum allowed value of bufspace (including metadata)"); 161 static long bufmallocspace; 162 SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 163 "Amount of malloced memory for buffers"); 164 static long maxbufmallocspace; 165 SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 166 0, "Maximum amount of malloced memory for buffers"); 167 static long lobufspace; 168 SYSCTL_LONG(_vfs, OID_AUTO, lobufspace, CTLFLAG_RW, &lobufspace, 0, 169 "Minimum amount of buffers we want to have"); 170 long hibufspace; 171 SYSCTL_LONG(_vfs, OID_AUTO, hibufspace, CTLFLAG_RW, &hibufspace, 0, 172 "Maximum allowed value of bufspace (excluding metadata)"); 173 long bufspacethresh; 174 SYSCTL_LONG(_vfs, OID_AUTO, bufspacethresh, CTLFLAG_RW, &bufspacethresh, 175 0, "Bufspace consumed before waking the daemon to free some"); 176 static int buffreekvacnt; 177 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0, 178 "Number of times we have freed the KVA space from some buffer"); 179 static int bufdefragcnt; 180 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0, 181 "Number of times we have had to repeat buffer allocation to defragment"); 182 static long lorunningspace; 183 SYSCTL_PROC(_vfs, OID_AUTO, lorunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE | 184 CTLFLAG_RW, &lorunningspace, 0, sysctl_runningspace, "L", 185 "Minimum preferred space used for in-progress I/O"); 186 static long hirunningspace; 187 SYSCTL_PROC(_vfs, OID_AUTO, hirunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE | 188 CTLFLAG_RW, &hirunningspace, 0, sysctl_runningspace, "L", 189 "Maximum amount of space to use for in-progress I/O"); 190 int dirtybufferflushes; 191 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes, 192 0, "Number of bdwrite to bawrite conversions to limit dirty buffers"); 193 int bdwriteskip; 194 SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip, 195 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk"); 196 int altbufferflushes; 197 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes, 198 0, "Number of fsync flushes to limit dirty buffers"); 199 static int recursiveflushes; 200 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes, 201 0, "Number of flushes skipped due to being recursive"); 202 static int numdirtybuffers; 203 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0, 204 "Number of buffers that are dirty (has unwritten changes) at the moment"); 205 static int lodirtybuffers; 206 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0, 207 "How many buffers we want to have free before bufdaemon can sleep"); 208 static int hidirtybuffers; 209 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0, 210 "When the number of dirty buffers is considered severe"); 211 int dirtybufthresh; 212 SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh, 213 0, "Number of bdwrite to bawrite conversions to clear dirty buffers"); 214 static int numfreebuffers; 215 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, 216 "Number of free buffers"); 217 static int lofreebuffers; 218 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0, 219 "Target number of free buffers"); 220 static int hifreebuffers; 221 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0, 222 "Threshold for clean buffer recycling"); 223 static int getnewbufcalls; 224 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0, 225 "Number of calls to getnewbuf"); 226 static int getnewbufrestarts; 227 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0, 228 "Number of times getnewbuf has had to restart a buffer acquisition"); 229 static int mappingrestarts; 230 SYSCTL_INT(_vfs, OID_AUTO, mappingrestarts, CTLFLAG_RW, &mappingrestarts, 0, 231 "Number of times getblk has had to restart a buffer mapping for " 232 "unmapped buffer"); 233 static int numbufallocfails; 234 SYSCTL_INT(_vfs, OID_AUTO, numbufallocfails, CTLFLAG_RW, &numbufallocfails, 0, 235 "Number of times buffer allocations failed"); 236 static int flushbufqtarget = 100; 237 SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0, 238 "Amount of work to do in flushbufqueues when helping bufdaemon"); 239 static long notbufdflushes; 240 SYSCTL_LONG(_vfs, OID_AUTO, notbufdflushes, CTLFLAG_RD, ¬bufdflushes, 0, 241 "Number of dirty buffer flushes done by the bufdaemon helpers"); 242 static long barrierwrites; 243 SYSCTL_LONG(_vfs, OID_AUTO, barrierwrites, CTLFLAG_RW, &barrierwrites, 0, 244 "Number of barrier writes"); 245 SYSCTL_INT(_vfs, OID_AUTO, unmapped_buf_allowed, CTLFLAG_RD, 246 &unmapped_buf_allowed, 0, 247 "Permit the use of the unmapped i/o"); 248 249 /* 250 * This lock synchronizes access to bd_request. 251 */ 252 static struct mtx_padalign bdlock; 253 254 /* 255 * This lock protects the runningbufreq and synchronizes runningbufwakeup and 256 * waitrunningbufspace(). 257 */ 258 static struct mtx_padalign rbreqlock; 259 260 /* 261 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it. 262 */ 263 static struct rwlock_padalign nblock; 264 265 /* 266 * Lock that protects bdirtywait. 267 */ 268 static struct mtx_padalign bdirtylock; 269 270 /* 271 * Wakeup point for bufdaemon, as well as indicator of whether it is already 272 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it 273 * is idling. 274 */ 275 static int bd_request; 276 277 /* 278 * Request/wakeup point for the bufspace daemon. 279 */ 280 static int bufspace_request; 281 282 /* 283 * Request for the buf daemon to write more buffers than is indicated by 284 * lodirtybuf. This may be necessary to push out excess dependencies or 285 * defragment the address space where a simple count of the number of dirty 286 * buffers is insufficient to characterize the demand for flushing them. 287 */ 288 static int bd_speedupreq; 289 290 /* 291 * bogus page -- for I/O to/from partially complete buffers 292 * this is a temporary solution to the problem, but it is not 293 * really that bad. it would be better to split the buffer 294 * for input in the case of buffers partially already in memory, 295 * but the code is intricate enough already. 296 */ 297 vm_page_t bogus_page; 298 299 /* 300 * Synchronization (sleep/wakeup) variable for active buffer space requests. 301 * Set when wait starts, cleared prior to wakeup(). 302 * Used in runningbufwakeup() and waitrunningbufspace(). 303 */ 304 static int runningbufreq; 305 306 /* 307 * Synchronization (sleep/wakeup) variable for buffer requests. 308 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done 309 * by and/or. 310 * Used in numdirtywakeup(), bufspace_wakeup(), bwillwrite(), 311 * getnewbuf(), and getblk(). 312 */ 313 static volatile int needsbuffer; 314 315 /* 316 * Synchronization for bwillwrite() waiters. 317 */ 318 static int bdirtywait; 319 320 /* 321 * Definitions for the buffer free lists. 322 */ 323 #define QUEUE_NONE 0 /* on no queue */ 324 #define QUEUE_EMPTY 1 /* empty buffer headers */ 325 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */ 326 #define QUEUE_CLEAN 3 /* non-B_DELWRI buffers */ 327 #define QUEUE_SENTINEL 1024 /* not an queue index, but mark for sentinel */ 328 329 /* Maximum number of clean buffer queues. */ 330 #define CLEAN_QUEUES 16 331 332 /* Configured number of clean queues. */ 333 static int clean_queues; 334 335 /* Maximum number of buffer queues. */ 336 #define BUFFER_QUEUES (QUEUE_CLEAN + CLEAN_QUEUES) 337 338 /* Queues for free buffers with various properties */ 339 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } }; 340 #ifdef INVARIANTS 341 static int bq_len[BUFFER_QUEUES]; 342 #endif 343 344 /* 345 * Lock for each bufqueue 346 */ 347 static struct mtx_padalign bqlocks[BUFFER_QUEUES]; 348 349 /* 350 * per-cpu empty buffer cache. 351 */ 352 uma_zone_t buf_zone; 353 354 /* 355 * Single global constant for BUF_WMESG, to avoid getting multiple references. 356 * buf_wmesg is referred from macros. 357 */ 358 const char *buf_wmesg = BUF_WMESG; 359 360 static int 361 sysctl_runningspace(SYSCTL_HANDLER_ARGS) 362 { 363 long value; 364 int error; 365 366 value = *(long *)arg1; 367 error = sysctl_handle_long(oidp, &value, 0, req); 368 if (error != 0 || req->newptr == NULL) 369 return (error); 370 mtx_lock(&rbreqlock); 371 if (arg1 == &hirunningspace) { 372 if (value < lorunningspace) 373 error = EINVAL; 374 else 375 hirunningspace = value; 376 } else { 377 KASSERT(arg1 == &lorunningspace, 378 ("%s: unknown arg1", __func__)); 379 if (value > hirunningspace) 380 error = EINVAL; 381 else 382 lorunningspace = value; 383 } 384 mtx_unlock(&rbreqlock); 385 return (error); 386 } 387 388 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 389 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 390 static int 391 sysctl_bufspace(SYSCTL_HANDLER_ARGS) 392 { 393 long lvalue; 394 int ivalue; 395 396 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long)) 397 return (sysctl_handle_long(oidp, arg1, arg2, req)); 398 lvalue = *(long *)arg1; 399 if (lvalue > INT_MAX) 400 /* On overflow, still write out a long to trigger ENOMEM. */ 401 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 402 ivalue = lvalue; 403 return (sysctl_handle_int(oidp, &ivalue, 0, req)); 404 } 405 #endif 406 407 static int 408 bqcleanq(void) 409 { 410 static int nextq; 411 412 return ((atomic_fetchadd_int(&nextq, 1) % clean_queues) + QUEUE_CLEAN); 413 } 414 415 static int 416 bqisclean(int qindex) 417 { 418 419 return (qindex >= QUEUE_CLEAN && qindex < QUEUE_CLEAN + CLEAN_QUEUES); 420 } 421 422 /* 423 * bqlock: 424 * 425 * Return the appropriate queue lock based on the index. 426 */ 427 static inline struct mtx * 428 bqlock(int qindex) 429 { 430 431 return (struct mtx *)&bqlocks[qindex]; 432 } 433 434 /* 435 * bdirtywakeup: 436 * 437 * Wakeup any bwillwrite() waiters. 438 */ 439 static void 440 bdirtywakeup(void) 441 { 442 mtx_lock(&bdirtylock); 443 if (bdirtywait) { 444 bdirtywait = 0; 445 wakeup(&bdirtywait); 446 } 447 mtx_unlock(&bdirtylock); 448 } 449 450 /* 451 * bdirtysub: 452 * 453 * Decrement the numdirtybuffers count by one and wakeup any 454 * threads blocked in bwillwrite(). 455 */ 456 static void 457 bdirtysub(void) 458 { 459 460 if (atomic_fetchadd_int(&numdirtybuffers, -1) == 461 (lodirtybuffers + hidirtybuffers) / 2) 462 bdirtywakeup(); 463 } 464 465 /* 466 * bdirtyadd: 467 * 468 * Increment the numdirtybuffers count by one and wakeup the buf 469 * daemon if needed. 470 */ 471 static void 472 bdirtyadd(void) 473 { 474 475 /* 476 * Only do the wakeup once as we cross the boundary. The 477 * buf daemon will keep running until the condition clears. 478 */ 479 if (atomic_fetchadd_int(&numdirtybuffers, 1) == 480 (lodirtybuffers + hidirtybuffers) / 2) 481 bd_wakeup(); 482 } 483 484 /* 485 * bufspace_wakeup: 486 * 487 * Called when buffer space is potentially available for recovery. 488 * getnewbuf() will block on this flag when it is unable to free 489 * sufficient buffer space. Buffer space becomes recoverable when 490 * bp's get placed back in the queues. 491 */ 492 static void 493 bufspace_wakeup(void) 494 { 495 496 /* 497 * If someone is waiting for bufspace, wake them up. 498 * 499 * Since needsbuffer is set prior to doing an additional queue 500 * scan it is safe to check for the flag prior to acquiring the 501 * lock. The thread that is preparing to scan again before 502 * blocking would discover the buf we released. 503 */ 504 if (needsbuffer) { 505 rw_rlock(&nblock); 506 if (atomic_cmpset_int(&needsbuffer, 1, 0) == 1) 507 wakeup(__DEVOLATILE(void *, &needsbuffer)); 508 rw_runlock(&nblock); 509 } 510 } 511 512 /* 513 * bufspace_daemonwakeup: 514 * 515 * Wakeup the daemon responsible for freeing clean bufs. 516 */ 517 static void 518 bufspace_daemonwakeup(void) 519 { 520 rw_rlock(&nblock); 521 if (bufspace_request == 0) { 522 bufspace_request = 1; 523 wakeup(&bufspace_request); 524 } 525 rw_runlock(&nblock); 526 } 527 528 /* 529 * bufspace_adjust: 530 * 531 * Adjust the reported bufspace for a KVA managed buffer, possibly 532 * waking any waiters. 533 */ 534 static void 535 bufspace_adjust(struct buf *bp, int bufsize) 536 { 537 long space; 538 int diff; 539 540 KASSERT((bp->b_flags & B_MALLOC) == 0, 541 ("bufspace_adjust: malloc buf %p", bp)); 542 diff = bufsize - bp->b_bufsize; 543 if (diff < 0) { 544 atomic_subtract_long(&bufspace, -diff); 545 bufspace_wakeup(); 546 } else { 547 space = atomic_fetchadd_long(&bufspace, diff); 548 /* Wake up the daemon on the transition. */ 549 if (space < bufspacethresh && space + diff >= bufspacethresh) 550 bufspace_daemonwakeup(); 551 } 552 bp->b_bufsize = bufsize; 553 } 554 555 /* 556 * bufspace_reserve: 557 * 558 * Reserve bufspace before calling allocbuf(). metadata has a 559 * different space limit than data. 560 */ 561 static int 562 bufspace_reserve(int size, bool metadata) 563 { 564 long limit; 565 long space; 566 567 if (metadata) 568 limit = maxbufspace; 569 else 570 limit = hibufspace; 571 do { 572 space = bufspace; 573 if (space + size > limit) 574 return (ENOSPC); 575 } while (atomic_cmpset_long(&bufspace, space, space + size) == 0); 576 577 /* Wake up the daemon on the transition. */ 578 if (space < bufspacethresh && space + size >= bufspacethresh) 579 bufspace_daemonwakeup(); 580 581 return (0); 582 } 583 584 /* 585 * bufspace_release: 586 * 587 * Release reserved bufspace after bufspace_adjust() has consumed it. 588 */ 589 static void 590 bufspace_release(int size) 591 { 592 atomic_subtract_long(&bufspace, size); 593 bufspace_wakeup(); 594 } 595 596 /* 597 * bufspace_wait: 598 * 599 * Wait for bufspace, acting as the buf daemon if a locked vnode is 600 * supplied. needsbuffer must be set in a safe fashion prior to 601 * polling for space. The operation must be re-tried on return. 602 */ 603 static void 604 bufspace_wait(struct vnode *vp, int gbflags, int slpflag, int slptimeo) 605 { 606 struct thread *td; 607 int error, fl, norunbuf; 608 609 if ((gbflags & GB_NOWAIT_BD) != 0) 610 return; 611 612 td = curthread; 613 rw_wlock(&nblock); 614 while (needsbuffer != 0) { 615 if (vp != NULL && vp->v_type != VCHR && 616 (td->td_pflags & TDP_BUFNEED) == 0) { 617 rw_wunlock(&nblock); 618 /* 619 * getblk() is called with a vnode locked, and 620 * some majority of the dirty buffers may as 621 * well belong to the vnode. Flushing the 622 * buffers there would make a progress that 623 * cannot be achieved by the buf_daemon, that 624 * cannot lock the vnode. 625 */ 626 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) | 627 (td->td_pflags & TDP_NORUNNINGBUF); 628 629 /* 630 * Play bufdaemon. The getnewbuf() function 631 * may be called while the thread owns lock 632 * for another dirty buffer for the same 633 * vnode, which makes it impossible to use 634 * VOP_FSYNC() there, due to the buffer lock 635 * recursion. 636 */ 637 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF; 638 fl = buf_flush(vp, flushbufqtarget); 639 td->td_pflags &= norunbuf; 640 rw_wlock(&nblock); 641 if (fl != 0) 642 continue; 643 if (needsbuffer == 0) 644 break; 645 } 646 error = rw_sleep(__DEVOLATILE(void *, &needsbuffer), &nblock, 647 (PRIBIO + 4) | slpflag, "newbuf", slptimeo); 648 if (error != 0) 649 break; 650 } 651 rw_wunlock(&nblock); 652 } 653 654 655 /* 656 * bufspace_daemon: 657 * 658 * buffer space management daemon. Tries to maintain some marginal 659 * amount of free buffer space so that requesting processes neither 660 * block nor work to reclaim buffers. 661 */ 662 static void 663 bufspace_daemon(void) 664 { 665 for (;;) { 666 kproc_suspend_check(bufspacedaemonproc); 667 668 /* 669 * Free buffers from the clean queue until we meet our 670 * targets. 671 * 672 * Theory of operation: The buffer cache is most efficient 673 * when some free buffer headers and space are always 674 * available to getnewbuf(). This daemon attempts to prevent 675 * the excessive blocking and synchronization associated 676 * with shortfall. It goes through three phases according 677 * demand: 678 * 679 * 1) The daemon wakes up voluntarily once per-second 680 * during idle periods when the counters are below 681 * the wakeup thresholds (bufspacethresh, lofreebuffers). 682 * 683 * 2) The daemon wakes up as we cross the thresholds 684 * ahead of any potential blocking. This may bounce 685 * slightly according to the rate of consumption and 686 * release. 687 * 688 * 3) The daemon and consumers are starved for working 689 * clean buffers. This is the 'bufspace' sleep below 690 * which will inefficiently trade bufs with bqrelse 691 * until we return to condition 2. 692 */ 693 while (bufspace > lobufspace || 694 numfreebuffers < hifreebuffers) { 695 if (buf_recycle(false) != 0) { 696 atomic_set_int(&needsbuffer, 1); 697 if (buf_recycle(false) != 0) { 698 rw_wlock(&nblock); 699 if (needsbuffer) 700 rw_sleep(__DEVOLATILE(void *, 701 &needsbuffer), &nblock, 702 PRIBIO|PDROP, "bufspace", 703 hz/10); 704 else 705 rw_wunlock(&nblock); 706 } 707 } 708 maybe_yield(); 709 } 710 711 /* 712 * Re-check our limits under the exclusive nblock. 713 */ 714 rw_wlock(&nblock); 715 if (bufspace < bufspacethresh && 716 numfreebuffers > lofreebuffers) { 717 bufspace_request = 0; 718 rw_sleep(&bufspace_request, &nblock, PRIBIO|PDROP, 719 "-", hz); 720 } else 721 rw_wunlock(&nblock); 722 } 723 } 724 725 static struct kproc_desc bufspace_kp = { 726 "bufspacedaemon", 727 bufspace_daemon, 728 &bufspacedaemonproc 729 }; 730 SYSINIT(bufspacedaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, 731 &bufspace_kp); 732 733 /* 734 * bufmallocadjust: 735 * 736 * Adjust the reported bufspace for a malloc managed buffer, possibly 737 * waking any waiters. 738 */ 739 static void 740 bufmallocadjust(struct buf *bp, int bufsize) 741 { 742 int diff; 743 744 KASSERT((bp->b_flags & B_MALLOC) != 0, 745 ("bufmallocadjust: non-malloc buf %p", bp)); 746 diff = bufsize - bp->b_bufsize; 747 if (diff < 0) 748 atomic_subtract_long(&bufmallocspace, -diff); 749 else 750 atomic_add_long(&bufmallocspace, diff); 751 bp->b_bufsize = bufsize; 752 } 753 754 /* 755 * runningwakeup: 756 * 757 * Wake up processes that are waiting on asynchronous writes to fall 758 * below lorunningspace. 759 */ 760 static void 761 runningwakeup(void) 762 { 763 764 mtx_lock(&rbreqlock); 765 if (runningbufreq) { 766 runningbufreq = 0; 767 wakeup(&runningbufreq); 768 } 769 mtx_unlock(&rbreqlock); 770 } 771 772 /* 773 * runningbufwakeup: 774 * 775 * Decrement the outstanding write count according. 776 */ 777 void 778 runningbufwakeup(struct buf *bp) 779 { 780 long space, bspace; 781 782 bspace = bp->b_runningbufspace; 783 if (bspace == 0) 784 return; 785 space = atomic_fetchadd_long(&runningbufspace, -bspace); 786 KASSERT(space >= bspace, ("runningbufspace underflow %ld %ld", 787 space, bspace)); 788 bp->b_runningbufspace = 0; 789 /* 790 * Only acquire the lock and wakeup on the transition from exceeding 791 * the threshold to falling below it. 792 */ 793 if (space < lorunningspace) 794 return; 795 if (space - bspace > lorunningspace) 796 return; 797 runningwakeup(); 798 } 799 800 /* 801 * waitrunningbufspace() 802 * 803 * runningbufspace is a measure of the amount of I/O currently 804 * running. This routine is used in async-write situations to 805 * prevent creating huge backups of pending writes to a device. 806 * Only asynchronous writes are governed by this function. 807 * 808 * This does NOT turn an async write into a sync write. It waits 809 * for earlier writes to complete and generally returns before the 810 * caller's write has reached the device. 811 */ 812 void 813 waitrunningbufspace(void) 814 { 815 816 mtx_lock(&rbreqlock); 817 while (runningbufspace > hirunningspace) { 818 runningbufreq = 1; 819 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 820 } 821 mtx_unlock(&rbreqlock); 822 } 823 824 825 /* 826 * vfs_buf_test_cache: 827 * 828 * Called when a buffer is extended. This function clears the B_CACHE 829 * bit if the newly extended portion of the buffer does not contain 830 * valid data. 831 */ 832 static __inline void 833 vfs_buf_test_cache(struct buf *bp, vm_ooffset_t foff, vm_offset_t off, 834 vm_offset_t size, vm_page_t m) 835 { 836 837 VM_OBJECT_ASSERT_LOCKED(m->object); 838 if (bp->b_flags & B_CACHE) { 839 int base = (foff + off) & PAGE_MASK; 840 if (vm_page_is_valid(m, base, size) == 0) 841 bp->b_flags &= ~B_CACHE; 842 } 843 } 844 845 /* Wake up the buffer daemon if necessary */ 846 static __inline void 847 bd_wakeup(void) 848 { 849 850 mtx_lock(&bdlock); 851 if (bd_request == 0) { 852 bd_request = 1; 853 wakeup(&bd_request); 854 } 855 mtx_unlock(&bdlock); 856 } 857 858 /* 859 * bd_speedup - speedup the buffer cache flushing code 860 */ 861 void 862 bd_speedup(void) 863 { 864 int needwake; 865 866 mtx_lock(&bdlock); 867 needwake = 0; 868 if (bd_speedupreq == 0 || bd_request == 0) 869 needwake = 1; 870 bd_speedupreq = 1; 871 bd_request = 1; 872 if (needwake) 873 wakeup(&bd_request); 874 mtx_unlock(&bdlock); 875 } 876 877 #ifndef NSWBUF_MIN 878 #define NSWBUF_MIN 16 879 #endif 880 881 #ifdef __i386__ 882 #define TRANSIENT_DENOM 5 883 #else 884 #define TRANSIENT_DENOM 10 885 #endif 886 887 /* 888 * Calculating buffer cache scaling values and reserve space for buffer 889 * headers. This is called during low level kernel initialization and 890 * may be called more then once. We CANNOT write to the memory area 891 * being reserved at this time. 892 */ 893 caddr_t 894 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 895 { 896 int tuned_nbuf; 897 long maxbuf, maxbuf_sz, buf_sz, biotmap_sz; 898 899 /* 900 * physmem_est is in pages. Convert it to kilobytes (assumes 901 * PAGE_SIZE is >= 1K) 902 */ 903 physmem_est = physmem_est * (PAGE_SIZE / 1024); 904 905 /* 906 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 907 * For the first 64MB of ram nominally allocate sufficient buffers to 908 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 909 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing 910 * the buffer cache we limit the eventual kva reservation to 911 * maxbcache bytes. 912 * 913 * factor represents the 1/4 x ram conversion. 914 */ 915 if (nbuf == 0) { 916 int factor = 4 * BKVASIZE / 1024; 917 918 nbuf = 50; 919 if (physmem_est > 4096) 920 nbuf += min((physmem_est - 4096) / factor, 921 65536 / factor); 922 if (physmem_est > 65536) 923 nbuf += min((physmem_est - 65536) * 2 / (factor * 5), 924 32 * 1024 * 1024 / (factor * 5)); 925 926 if (maxbcache && nbuf > maxbcache / BKVASIZE) 927 nbuf = maxbcache / BKVASIZE; 928 tuned_nbuf = 1; 929 } else 930 tuned_nbuf = 0; 931 932 /* XXX Avoid unsigned long overflows later on with maxbufspace. */ 933 maxbuf = (LONG_MAX / 3) / BKVASIZE; 934 if (nbuf > maxbuf) { 935 if (!tuned_nbuf) 936 printf("Warning: nbufs lowered from %d to %ld\n", nbuf, 937 maxbuf); 938 nbuf = maxbuf; 939 } 940 941 /* 942 * Ideal allocation size for the transient bio submap is 10% 943 * of the maximal space buffer map. This roughly corresponds 944 * to the amount of the buffer mapped for typical UFS load. 945 * 946 * Clip the buffer map to reserve space for the transient 947 * BIOs, if its extent is bigger than 90% (80% on i386) of the 948 * maximum buffer map extent on the platform. 949 * 950 * The fall-back to the maxbuf in case of maxbcache unset, 951 * allows to not trim the buffer KVA for the architectures 952 * with ample KVA space. 953 */ 954 if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) { 955 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE; 956 buf_sz = (long)nbuf * BKVASIZE; 957 if (buf_sz < maxbuf_sz / TRANSIENT_DENOM * 958 (TRANSIENT_DENOM - 1)) { 959 /* 960 * There is more KVA than memory. Do not 961 * adjust buffer map size, and assign the rest 962 * of maxbuf to transient map. 963 */ 964 biotmap_sz = maxbuf_sz - buf_sz; 965 } else { 966 /* 967 * Buffer map spans all KVA we could afford on 968 * this platform. Give 10% (20% on i386) of 969 * the buffer map to the transient bio map. 970 */ 971 biotmap_sz = buf_sz / TRANSIENT_DENOM; 972 buf_sz -= biotmap_sz; 973 } 974 if (biotmap_sz / INT_MAX > MAXPHYS) 975 bio_transient_maxcnt = INT_MAX; 976 else 977 bio_transient_maxcnt = biotmap_sz / MAXPHYS; 978 /* 979 * Artificially limit to 1024 simultaneous in-flight I/Os 980 * using the transient mapping. 981 */ 982 if (bio_transient_maxcnt > 1024) 983 bio_transient_maxcnt = 1024; 984 if (tuned_nbuf) 985 nbuf = buf_sz / BKVASIZE; 986 } 987 988 /* 989 * swbufs are used as temporary holders for I/O, such as paging I/O. 990 * We have no less then 16 and no more then 256. 991 */ 992 nswbuf = min(nbuf / 4, 256); 993 TUNABLE_INT_FETCH("kern.nswbuf", &nswbuf); 994 if (nswbuf < NSWBUF_MIN) 995 nswbuf = NSWBUF_MIN; 996 997 /* 998 * Reserve space for the buffer cache buffers 999 */ 1000 swbuf = (void *)v; 1001 v = (caddr_t)(swbuf + nswbuf); 1002 buf = (void *)v; 1003 v = (caddr_t)(buf + nbuf); 1004 1005 return(v); 1006 } 1007 1008 /* Initialize the buffer subsystem. Called before use of any buffers. */ 1009 void 1010 bufinit(void) 1011 { 1012 struct buf *bp; 1013 int i; 1014 1015 CTASSERT(MAXBCACHEBUF >= MAXBSIZE); 1016 mtx_init(&bqlocks[QUEUE_DIRTY], "bufq dirty lock", NULL, MTX_DEF); 1017 mtx_init(&bqlocks[QUEUE_EMPTY], "bufq empty lock", NULL, MTX_DEF); 1018 for (i = QUEUE_CLEAN; i < QUEUE_CLEAN + CLEAN_QUEUES; i++) 1019 mtx_init(&bqlocks[i], "bufq clean lock", NULL, MTX_DEF); 1020 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 1021 rw_init(&nblock, "needsbuffer lock"); 1022 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 1023 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF); 1024 1025 /* next, make a null set of free lists */ 1026 for (i = 0; i < BUFFER_QUEUES; i++) 1027 TAILQ_INIT(&bufqueues[i]); 1028 1029 unmapped_buf = (caddr_t)kva_alloc(MAXPHYS); 1030 1031 /* finally, initialize each buffer header and stick on empty q */ 1032 for (i = 0; i < nbuf; i++) { 1033 bp = &buf[i]; 1034 bzero(bp, sizeof *bp); 1035 bp->b_flags = B_INVAL; 1036 bp->b_rcred = NOCRED; 1037 bp->b_wcred = NOCRED; 1038 bp->b_qindex = QUEUE_EMPTY; 1039 bp->b_xflags = 0; 1040 bp->b_data = bp->b_kvabase = unmapped_buf; 1041 LIST_INIT(&bp->b_dep); 1042 BUF_LOCKINIT(bp); 1043 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 1044 #ifdef INVARIANTS 1045 bq_len[QUEUE_EMPTY]++; 1046 #endif 1047 } 1048 1049 /* 1050 * maxbufspace is the absolute maximum amount of buffer space we are 1051 * allowed to reserve in KVM and in real terms. The absolute maximum 1052 * is nominally used by metadata. hibufspace is the nominal maximum 1053 * used by most other requests. The differential is required to 1054 * ensure that metadata deadlocks don't occur. 1055 * 1056 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 1057 * this may result in KVM fragmentation which is not handled optimally 1058 * by the system. XXX This is less true with vmem. We could use 1059 * PAGE_SIZE. 1060 */ 1061 maxbufspace = (long)nbuf * BKVASIZE; 1062 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - MAXBCACHEBUF * 10); 1063 lobufspace = (hibufspace / 20) * 19; /* 95% */ 1064 bufspacethresh = lobufspace + (hibufspace - lobufspace) / 2; 1065 1066 /* 1067 * Note: The 16 MiB upper limit for hirunningspace was chosen 1068 * arbitrarily and may need further tuning. It corresponds to 1069 * 128 outstanding write IO requests (if IO size is 128 KiB), 1070 * which fits with many RAID controllers' tagged queuing limits. 1071 * The lower 1 MiB limit is the historical upper limit for 1072 * hirunningspace. 1073 */ 1074 hirunningspace = lmax(lmin(roundup(hibufspace / 64, MAXBCACHEBUF), 1075 16 * 1024 * 1024), 1024 * 1024); 1076 lorunningspace = roundup((hirunningspace * 2) / 3, MAXBCACHEBUF); 1077 1078 /* 1079 * Limit the amount of malloc memory since it is wired permanently into 1080 * the kernel space. Even though this is accounted for in the buffer 1081 * allocation, we don't want the malloced region to grow uncontrolled. 1082 * The malloc scheme improves memory utilization significantly on 1083 * average (small) directories. 1084 */ 1085 maxbufmallocspace = hibufspace / 20; 1086 1087 /* 1088 * Reduce the chance of a deadlock occurring by limiting the number 1089 * of delayed-write dirty buffers we allow to stack up. 1090 */ 1091 hidirtybuffers = nbuf / 4 + 20; 1092 dirtybufthresh = hidirtybuffers * 9 / 10; 1093 numdirtybuffers = 0; 1094 /* 1095 * To support extreme low-memory systems, make sure hidirtybuffers 1096 * cannot eat up all available buffer space. This occurs when our 1097 * minimum cannot be met. We try to size hidirtybuffers to 3/4 our 1098 * buffer space assuming BKVASIZE'd buffers. 1099 */ 1100 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 1101 hidirtybuffers >>= 1; 1102 } 1103 lodirtybuffers = hidirtybuffers / 2; 1104 1105 /* 1106 * lofreebuffers should be sufficient to avoid stalling waiting on 1107 * buf headers under heavy utilization. The bufs in per-cpu caches 1108 * are counted as free but will be unavailable to threads executing 1109 * on other cpus. 1110 * 1111 * hifreebuffers is the free target for the bufspace daemon. This 1112 * should be set appropriately to limit work per-iteration. 1113 */ 1114 lofreebuffers = MIN((nbuf / 25) + (20 * mp_ncpus), 128 * mp_ncpus); 1115 hifreebuffers = (3 * lofreebuffers) / 2; 1116 numfreebuffers = nbuf; 1117 1118 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ | 1119 VM_ALLOC_NORMAL | VM_ALLOC_WIRED); 1120 1121 /* Setup the kva and free list allocators. */ 1122 vmem_set_reclaim(buffer_arena, bufkva_reclaim); 1123 buf_zone = uma_zcache_create("buf free cache", sizeof(struct buf), 1124 NULL, NULL, NULL, NULL, buf_import, buf_release, NULL, 0); 1125 1126 /* 1127 * Size the clean queue according to the amount of buffer space. 1128 * One queue per-256mb up to the max. More queues gives better 1129 * concurrency but less accurate LRU. 1130 */ 1131 clean_queues = MIN(howmany(maxbufspace, 256*1024*1024), CLEAN_QUEUES); 1132 1133 } 1134 1135 #ifdef INVARIANTS 1136 static inline void 1137 vfs_buf_check_mapped(struct buf *bp) 1138 { 1139 1140 KASSERT(bp->b_kvabase != unmapped_buf, 1141 ("mapped buf: b_kvabase was not updated %p", bp)); 1142 KASSERT(bp->b_data != unmapped_buf, 1143 ("mapped buf: b_data was not updated %p", bp)); 1144 KASSERT(bp->b_data < unmapped_buf || bp->b_data >= unmapped_buf + 1145 MAXPHYS, ("b_data + b_offset unmapped %p", bp)); 1146 } 1147 1148 static inline void 1149 vfs_buf_check_unmapped(struct buf *bp) 1150 { 1151 1152 KASSERT(bp->b_data == unmapped_buf, 1153 ("unmapped buf: corrupted b_data %p", bp)); 1154 } 1155 1156 #define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp) 1157 #define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp) 1158 #else 1159 #define BUF_CHECK_MAPPED(bp) do {} while (0) 1160 #define BUF_CHECK_UNMAPPED(bp) do {} while (0) 1161 #endif 1162 1163 static int 1164 isbufbusy(struct buf *bp) 1165 { 1166 if (((bp->b_flags & B_INVAL) == 0 && BUF_ISLOCKED(bp)) || 1167 ((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI)) 1168 return (1); 1169 return (0); 1170 } 1171 1172 /* 1173 * Shutdown the system cleanly to prepare for reboot, halt, or power off. 1174 */ 1175 void 1176 bufshutdown(int show_busybufs) 1177 { 1178 static int first_buf_printf = 1; 1179 struct buf *bp; 1180 int iter, nbusy, pbusy; 1181 #ifndef PREEMPTION 1182 int subiter; 1183 #endif 1184 1185 /* 1186 * Sync filesystems for shutdown 1187 */ 1188 wdog_kern_pat(WD_LASTVAL); 1189 sys_sync(curthread, NULL); 1190 1191 /* 1192 * With soft updates, some buffers that are 1193 * written will be remarked as dirty until other 1194 * buffers are written. 1195 */ 1196 for (iter = pbusy = 0; iter < 20; iter++) { 1197 nbusy = 0; 1198 for (bp = &buf[nbuf]; --bp >= buf; ) 1199 if (isbufbusy(bp)) 1200 nbusy++; 1201 if (nbusy == 0) { 1202 if (first_buf_printf) 1203 printf("All buffers synced."); 1204 break; 1205 } 1206 if (first_buf_printf) { 1207 printf("Syncing disks, buffers remaining... "); 1208 first_buf_printf = 0; 1209 } 1210 printf("%d ", nbusy); 1211 if (nbusy < pbusy) 1212 iter = 0; 1213 pbusy = nbusy; 1214 1215 wdog_kern_pat(WD_LASTVAL); 1216 sys_sync(curthread, NULL); 1217 1218 #ifdef PREEMPTION 1219 /* 1220 * Drop Giant and spin for a while to allow 1221 * interrupt threads to run. 1222 */ 1223 DROP_GIANT(); 1224 DELAY(50000 * iter); 1225 PICKUP_GIANT(); 1226 #else 1227 /* 1228 * Drop Giant and context switch several times to 1229 * allow interrupt threads to run. 1230 */ 1231 DROP_GIANT(); 1232 for (subiter = 0; subiter < 50 * iter; subiter++) { 1233 thread_lock(curthread); 1234 mi_switch(SW_VOL, NULL); 1235 thread_unlock(curthread); 1236 DELAY(1000); 1237 } 1238 PICKUP_GIANT(); 1239 #endif 1240 } 1241 printf("\n"); 1242 /* 1243 * Count only busy local buffers to prevent forcing 1244 * a fsck if we're just a client of a wedged NFS server 1245 */ 1246 nbusy = 0; 1247 for (bp = &buf[nbuf]; --bp >= buf; ) { 1248 if (isbufbusy(bp)) { 1249 #if 0 1250 /* XXX: This is bogus. We should probably have a BO_REMOTE flag instead */ 1251 if (bp->b_dev == NULL) { 1252 TAILQ_REMOVE(&mountlist, 1253 bp->b_vp->v_mount, mnt_list); 1254 continue; 1255 } 1256 #endif 1257 nbusy++; 1258 if (show_busybufs > 0) { 1259 printf( 1260 "%d: buf:%p, vnode:%p, flags:%0x, blkno:%jd, lblkno:%jd, buflock:", 1261 nbusy, bp, bp->b_vp, bp->b_flags, 1262 (intmax_t)bp->b_blkno, 1263 (intmax_t)bp->b_lblkno); 1264 BUF_LOCKPRINTINFO(bp); 1265 if (show_busybufs > 1) 1266 vn_printf(bp->b_vp, 1267 "vnode content: "); 1268 } 1269 } 1270 } 1271 if (nbusy) { 1272 /* 1273 * Failed to sync all blocks. Indicate this and don't 1274 * unmount filesystems (thus forcing an fsck on reboot). 1275 */ 1276 printf("Giving up on %d buffers\n", nbusy); 1277 DELAY(5000000); /* 5 seconds */ 1278 } else { 1279 if (!first_buf_printf) 1280 printf("Final sync complete\n"); 1281 /* 1282 * Unmount filesystems 1283 */ 1284 if (panicstr == NULL) 1285 vfs_unmountall(); 1286 } 1287 swapoff_all(); 1288 DELAY(100000); /* wait for console output to finish */ 1289 } 1290 1291 static void 1292 bpmap_qenter(struct buf *bp) 1293 { 1294 1295 BUF_CHECK_MAPPED(bp); 1296 1297 /* 1298 * bp->b_data is relative to bp->b_offset, but 1299 * bp->b_offset may be offset into the first page. 1300 */ 1301 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data); 1302 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages); 1303 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 1304 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 1305 } 1306 1307 /* 1308 * binsfree: 1309 * 1310 * Insert the buffer into the appropriate free list. 1311 */ 1312 static void 1313 binsfree(struct buf *bp, int qindex) 1314 { 1315 struct mtx *olock, *nlock; 1316 1317 if (qindex != QUEUE_EMPTY) { 1318 BUF_ASSERT_XLOCKED(bp); 1319 } 1320 1321 /* 1322 * Stick to the same clean queue for the lifetime of the buf to 1323 * limit locking below. Otherwise pick ont sequentially. 1324 */ 1325 if (qindex == QUEUE_CLEAN) { 1326 if (bqisclean(bp->b_qindex)) 1327 qindex = bp->b_qindex; 1328 else 1329 qindex = bqcleanq(); 1330 } 1331 1332 /* 1333 * Handle delayed bremfree() processing. 1334 */ 1335 nlock = bqlock(qindex); 1336 if (bp->b_flags & B_REMFREE) { 1337 olock = bqlock(bp->b_qindex); 1338 mtx_lock(olock); 1339 bremfreel(bp); 1340 if (olock != nlock) { 1341 mtx_unlock(olock); 1342 mtx_lock(nlock); 1343 } 1344 } else 1345 mtx_lock(nlock); 1346 1347 if (bp->b_qindex != QUEUE_NONE) 1348 panic("binsfree: free buffer onto another queue???"); 1349 1350 bp->b_qindex = qindex; 1351 if (bp->b_flags & B_AGE) 1352 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1353 else 1354 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1355 #ifdef INVARIANTS 1356 bq_len[bp->b_qindex]++; 1357 #endif 1358 mtx_unlock(nlock); 1359 } 1360 1361 /* 1362 * buf_free: 1363 * 1364 * Free a buffer to the buf zone once it no longer has valid contents. 1365 */ 1366 static void 1367 buf_free(struct buf *bp) 1368 { 1369 1370 if (bp->b_flags & B_REMFREE) 1371 bremfreef(bp); 1372 if (bp->b_vflags & BV_BKGRDINPROG) 1373 panic("losing buffer 1"); 1374 if (bp->b_rcred != NOCRED) { 1375 crfree(bp->b_rcred); 1376 bp->b_rcred = NOCRED; 1377 } 1378 if (bp->b_wcred != NOCRED) { 1379 crfree(bp->b_wcred); 1380 bp->b_wcred = NOCRED; 1381 } 1382 if (!LIST_EMPTY(&bp->b_dep)) 1383 buf_deallocate(bp); 1384 bufkva_free(bp); 1385 BUF_UNLOCK(bp); 1386 uma_zfree(buf_zone, bp); 1387 atomic_add_int(&numfreebuffers, 1); 1388 bufspace_wakeup(); 1389 } 1390 1391 /* 1392 * buf_import: 1393 * 1394 * Import bufs into the uma cache from the buf list. The system still 1395 * expects a static array of bufs and much of the synchronization 1396 * around bufs assumes type stable storage. As a result, UMA is used 1397 * only as a per-cpu cache of bufs still maintained on a global list. 1398 */ 1399 static int 1400 buf_import(void *arg, void **store, int cnt, int flags) 1401 { 1402 struct buf *bp; 1403 int i; 1404 1405 mtx_lock(&bqlocks[QUEUE_EMPTY]); 1406 for (i = 0; i < cnt; i++) { 1407 bp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1408 if (bp == NULL) 1409 break; 1410 bremfreel(bp); 1411 store[i] = bp; 1412 } 1413 mtx_unlock(&bqlocks[QUEUE_EMPTY]); 1414 1415 return (i); 1416 } 1417 1418 /* 1419 * buf_release: 1420 * 1421 * Release bufs from the uma cache back to the buffer queues. 1422 */ 1423 static void 1424 buf_release(void *arg, void **store, int cnt) 1425 { 1426 int i; 1427 1428 for (i = 0; i < cnt; i++) 1429 binsfree(store[i], QUEUE_EMPTY); 1430 } 1431 1432 /* 1433 * buf_alloc: 1434 * 1435 * Allocate an empty buffer header. 1436 */ 1437 static struct buf * 1438 buf_alloc(void) 1439 { 1440 struct buf *bp; 1441 1442 bp = uma_zalloc(buf_zone, M_NOWAIT); 1443 if (bp == NULL) { 1444 bufspace_daemonwakeup(); 1445 atomic_add_int(&numbufallocfails, 1); 1446 return (NULL); 1447 } 1448 1449 /* 1450 * Wake-up the bufspace daemon on transition. 1451 */ 1452 if (atomic_fetchadd_int(&numfreebuffers, -1) == lofreebuffers) 1453 bufspace_daemonwakeup(); 1454 1455 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1456 panic("getnewbuf_empty: Locked buf %p on free queue.", bp); 1457 1458 KASSERT(bp->b_vp == NULL, 1459 ("bp: %p still has vnode %p.", bp, bp->b_vp)); 1460 KASSERT((bp->b_flags & (B_DELWRI | B_NOREUSE)) == 0, 1461 ("invalid buffer %p flags %#x", bp, bp->b_flags)); 1462 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 1463 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags)); 1464 KASSERT(bp->b_npages == 0, 1465 ("bp: %p still has %d vm pages\n", bp, bp->b_npages)); 1466 KASSERT(bp->b_kvasize == 0, ("bp: %p still has kva\n", bp)); 1467 KASSERT(bp->b_bufsize == 0, ("bp: %p still has bufspace\n", bp)); 1468 1469 bp->b_flags = 0; 1470 bp->b_ioflags = 0; 1471 bp->b_xflags = 0; 1472 bp->b_vflags = 0; 1473 bp->b_vp = NULL; 1474 bp->b_blkno = bp->b_lblkno = 0; 1475 bp->b_offset = NOOFFSET; 1476 bp->b_iodone = 0; 1477 bp->b_error = 0; 1478 bp->b_resid = 0; 1479 bp->b_bcount = 0; 1480 bp->b_npages = 0; 1481 bp->b_dirtyoff = bp->b_dirtyend = 0; 1482 bp->b_bufobj = NULL; 1483 bp->b_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 #ifdef RACCT 1789 if (racct_enable) { 1790 PROC_LOCK(curproc); 1791 racct_add_buf(curproc, rabp, 0); 1792 PROC_UNLOCK(curproc); 1793 } 1794 #endif /* RACCT */ 1795 curthread->td_ru.ru_inblock++; 1796 } 1797 rabp->b_flags |= B_ASYNC; 1798 rabp->b_flags &= ~B_INVAL; 1799 rabp->b_ioflags &= ~BIO_ERROR; 1800 rabp->b_iocmd = BIO_READ; 1801 if (rabp->b_rcred == NOCRED && cred != NOCRED) 1802 rabp->b_rcred = crhold(cred); 1803 vfs_busy_pages(rabp, 0); 1804 BUF_KERNPROC(rabp); 1805 rabp->b_iooffset = dbtob(rabp->b_blkno); 1806 bstrategy(rabp); 1807 } else { 1808 brelse(rabp); 1809 } 1810 } 1811 } 1812 1813 /* 1814 * Entry point for bread() and breadn() via #defines in sys/buf.h. 1815 * 1816 * Get a buffer with the specified data. Look in the cache first. We 1817 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 1818 * is set, the buffer is valid and we do not have to do anything, see 1819 * getblk(). Also starts asynchronous I/O on read-ahead blocks. 1820 * 1821 * Always return a NULL buffer pointer (in bpp) when returning an error. 1822 */ 1823 int 1824 breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno, 1825 int *rabsize, int cnt, struct ucred *cred, int flags, struct buf **bpp) 1826 { 1827 struct buf *bp; 1828 int rv = 0, readwait = 0; 1829 1830 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 1831 /* 1832 * Can only return NULL if GB_LOCK_NOWAIT flag is specified. 1833 */ 1834 *bpp = bp = getblk(vp, blkno, size, 0, 0, flags); 1835 if (bp == NULL) 1836 return (EBUSY); 1837 1838 /* if not found in cache, do some I/O */ 1839 if ((bp->b_flags & B_CACHE) == 0) { 1840 if (!TD_IS_IDLETHREAD(curthread)) { 1841 #ifdef RACCT 1842 if (racct_enable) { 1843 PROC_LOCK(curproc); 1844 racct_add_buf(curproc, bp, 0); 1845 PROC_UNLOCK(curproc); 1846 } 1847 #endif /* RACCT */ 1848 curthread->td_ru.ru_inblock++; 1849 } 1850 bp->b_iocmd = BIO_READ; 1851 bp->b_flags &= ~B_INVAL; 1852 bp->b_ioflags &= ~BIO_ERROR; 1853 if (bp->b_rcred == NOCRED && cred != NOCRED) 1854 bp->b_rcred = crhold(cred); 1855 vfs_busy_pages(bp, 0); 1856 bp->b_iooffset = dbtob(bp->b_blkno); 1857 bstrategy(bp); 1858 ++readwait; 1859 } 1860 1861 breada(vp, rablkno, rabsize, cnt, cred); 1862 1863 if (readwait) { 1864 rv = bufwait(bp); 1865 if (rv != 0) { 1866 brelse(bp); 1867 *bpp = NULL; 1868 } 1869 } 1870 return (rv); 1871 } 1872 1873 /* 1874 * Write, release buffer on completion. (Done by iodone 1875 * if async). Do not bother writing anything if the buffer 1876 * is invalid. 1877 * 1878 * Note that we set B_CACHE here, indicating that buffer is 1879 * fully valid and thus cacheable. This is true even of NFS 1880 * now so we set it generally. This could be set either here 1881 * or in biodone() since the I/O is synchronous. We put it 1882 * here. 1883 */ 1884 int 1885 bufwrite(struct buf *bp) 1886 { 1887 int oldflags; 1888 struct vnode *vp; 1889 long space; 1890 int vp_md; 1891 1892 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1893 if ((bp->b_bufobj->bo_flag & BO_DEAD) != 0) { 1894 bp->b_flags |= B_INVAL | B_RELBUF; 1895 bp->b_flags &= ~B_CACHE; 1896 brelse(bp); 1897 return (ENXIO); 1898 } 1899 if (bp->b_flags & B_INVAL) { 1900 brelse(bp); 1901 return (0); 1902 } 1903 1904 if (bp->b_flags & B_BARRIER) 1905 barrierwrites++; 1906 1907 oldflags = bp->b_flags; 1908 1909 BUF_ASSERT_HELD(bp); 1910 1911 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 1912 ("FFS background buffer should not get here %p", bp)); 1913 1914 vp = bp->b_vp; 1915 if (vp) 1916 vp_md = vp->v_vflag & VV_MD; 1917 else 1918 vp_md = 0; 1919 1920 /* 1921 * Mark the buffer clean. Increment the bufobj write count 1922 * before bundirty() call, to prevent other thread from seeing 1923 * empty dirty list and zero counter for writes in progress, 1924 * falsely indicating that the bufobj is clean. 1925 */ 1926 bufobj_wref(bp->b_bufobj); 1927 bundirty(bp); 1928 1929 bp->b_flags &= ~B_DONE; 1930 bp->b_ioflags &= ~BIO_ERROR; 1931 bp->b_flags |= B_CACHE; 1932 bp->b_iocmd = BIO_WRITE; 1933 1934 vfs_busy_pages(bp, 1); 1935 1936 /* 1937 * Normal bwrites pipeline writes 1938 */ 1939 bp->b_runningbufspace = bp->b_bufsize; 1940 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace); 1941 1942 if (!TD_IS_IDLETHREAD(curthread)) { 1943 #ifdef RACCT 1944 if (racct_enable) { 1945 PROC_LOCK(curproc); 1946 racct_add_buf(curproc, bp, 1); 1947 PROC_UNLOCK(curproc); 1948 } 1949 #endif /* RACCT */ 1950 curthread->td_ru.ru_oublock++; 1951 } 1952 if (oldflags & B_ASYNC) 1953 BUF_KERNPROC(bp); 1954 bp->b_iooffset = dbtob(bp->b_blkno); 1955 bstrategy(bp); 1956 1957 if ((oldflags & B_ASYNC) == 0) { 1958 int rtval = bufwait(bp); 1959 brelse(bp); 1960 return (rtval); 1961 } else if (space > hirunningspace) { 1962 /* 1963 * don't allow the async write to saturate the I/O 1964 * system. We will not deadlock here because 1965 * we are blocking waiting for I/O that is already in-progress 1966 * to complete. We do not block here if it is the update 1967 * or syncer daemon trying to clean up as that can lead 1968 * to deadlock. 1969 */ 1970 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 1971 waitrunningbufspace(); 1972 } 1973 1974 return (0); 1975 } 1976 1977 void 1978 bufbdflush(struct bufobj *bo, struct buf *bp) 1979 { 1980 struct buf *nbp; 1981 1982 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 1983 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 1984 altbufferflushes++; 1985 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 1986 BO_LOCK(bo); 1987 /* 1988 * Try to find a buffer to flush. 1989 */ 1990 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 1991 if ((nbp->b_vflags & BV_BKGRDINPROG) || 1992 BUF_LOCK(nbp, 1993 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 1994 continue; 1995 if (bp == nbp) 1996 panic("bdwrite: found ourselves"); 1997 BO_UNLOCK(bo); 1998 /* Don't countdeps with the bo lock held. */ 1999 if (buf_countdeps(nbp, 0)) { 2000 BO_LOCK(bo); 2001 BUF_UNLOCK(nbp); 2002 continue; 2003 } 2004 if (nbp->b_flags & B_CLUSTEROK) { 2005 vfs_bio_awrite(nbp); 2006 } else { 2007 bremfree(nbp); 2008 bawrite(nbp); 2009 } 2010 dirtybufferflushes++; 2011 break; 2012 } 2013 if (nbp == NULL) 2014 BO_UNLOCK(bo); 2015 } 2016 } 2017 2018 /* 2019 * Delayed write. (Buffer is marked dirty). Do not bother writing 2020 * anything if the buffer is marked invalid. 2021 * 2022 * Note that since the buffer must be completely valid, we can safely 2023 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 2024 * biodone() in order to prevent getblk from writing the buffer 2025 * out synchronously. 2026 */ 2027 void 2028 bdwrite(struct buf *bp) 2029 { 2030 struct thread *td = curthread; 2031 struct vnode *vp; 2032 struct bufobj *bo; 2033 2034 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2035 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2036 KASSERT((bp->b_flags & B_BARRIER) == 0, 2037 ("Barrier request in delayed write %p", bp)); 2038 BUF_ASSERT_HELD(bp); 2039 2040 if (bp->b_flags & B_INVAL) { 2041 brelse(bp); 2042 return; 2043 } 2044 2045 /* 2046 * If we have too many dirty buffers, don't create any more. 2047 * If we are wildly over our limit, then force a complete 2048 * cleanup. Otherwise, just keep the situation from getting 2049 * out of control. Note that we have to avoid a recursive 2050 * disaster and not try to clean up after our own cleanup! 2051 */ 2052 vp = bp->b_vp; 2053 bo = bp->b_bufobj; 2054 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 2055 td->td_pflags |= TDP_INBDFLUSH; 2056 BO_BDFLUSH(bo, bp); 2057 td->td_pflags &= ~TDP_INBDFLUSH; 2058 } else 2059 recursiveflushes++; 2060 2061 bdirty(bp); 2062 /* 2063 * Set B_CACHE, indicating that the buffer is fully valid. This is 2064 * true even of NFS now. 2065 */ 2066 bp->b_flags |= B_CACHE; 2067 2068 /* 2069 * This bmap keeps the system from needing to do the bmap later, 2070 * perhaps when the system is attempting to do a sync. Since it 2071 * is likely that the indirect block -- or whatever other datastructure 2072 * that the filesystem needs is still in memory now, it is a good 2073 * thing to do this. Note also, that if the pageout daemon is 2074 * requesting a sync -- there might not be enough memory to do 2075 * the bmap then... So, this is important to do. 2076 */ 2077 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 2078 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 2079 } 2080 2081 /* 2082 * Set the *dirty* buffer range based upon the VM system dirty 2083 * pages. 2084 * 2085 * Mark the buffer pages as clean. We need to do this here to 2086 * satisfy the vnode_pager and the pageout daemon, so that it 2087 * thinks that the pages have been "cleaned". Note that since 2088 * the pages are in a delayed write buffer -- the VFS layer 2089 * "will" see that the pages get written out on the next sync, 2090 * or perhaps the cluster will be completed. 2091 */ 2092 vfs_clean_pages_dirty_buf(bp); 2093 bqrelse(bp); 2094 2095 /* 2096 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 2097 * due to the softdep code. 2098 */ 2099 } 2100 2101 /* 2102 * bdirty: 2103 * 2104 * Turn buffer into delayed write request. We must clear BIO_READ and 2105 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 2106 * itself to properly update it in the dirty/clean lists. We mark it 2107 * B_DONE to ensure that any asynchronization of the buffer properly 2108 * clears B_DONE ( else a panic will occur later ). 2109 * 2110 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 2111 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 2112 * should only be called if the buffer is known-good. 2113 * 2114 * Since the buffer is not on a queue, we do not update the numfreebuffers 2115 * count. 2116 * 2117 * The buffer must be on QUEUE_NONE. 2118 */ 2119 void 2120 bdirty(struct buf *bp) 2121 { 2122 2123 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 2124 bp, bp->b_vp, bp->b_flags); 2125 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2126 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 2127 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 2128 BUF_ASSERT_HELD(bp); 2129 bp->b_flags &= ~(B_RELBUF); 2130 bp->b_iocmd = BIO_WRITE; 2131 2132 if ((bp->b_flags & B_DELWRI) == 0) { 2133 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 2134 reassignbuf(bp); 2135 bdirtyadd(); 2136 } 2137 } 2138 2139 /* 2140 * bundirty: 2141 * 2142 * Clear B_DELWRI for buffer. 2143 * 2144 * Since the buffer is not on a queue, we do not update the numfreebuffers 2145 * count. 2146 * 2147 * The buffer must be on QUEUE_NONE. 2148 */ 2149 2150 void 2151 bundirty(struct buf *bp) 2152 { 2153 2154 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2155 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2156 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 2157 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 2158 BUF_ASSERT_HELD(bp); 2159 2160 if (bp->b_flags & B_DELWRI) { 2161 bp->b_flags &= ~B_DELWRI; 2162 reassignbuf(bp); 2163 bdirtysub(); 2164 } 2165 /* 2166 * Since it is now being written, we can clear its deferred write flag. 2167 */ 2168 bp->b_flags &= ~B_DEFERRED; 2169 } 2170 2171 /* 2172 * bawrite: 2173 * 2174 * Asynchronous write. Start output on a buffer, but do not wait for 2175 * it to complete. The buffer is released when the output completes. 2176 * 2177 * bwrite() ( or the VOP routine anyway ) is responsible for handling 2178 * B_INVAL buffers. Not us. 2179 */ 2180 void 2181 bawrite(struct buf *bp) 2182 { 2183 2184 bp->b_flags |= B_ASYNC; 2185 (void) bwrite(bp); 2186 } 2187 2188 /* 2189 * babarrierwrite: 2190 * 2191 * Asynchronous barrier write. Start output on a buffer, but do not 2192 * wait for it to complete. Place a write barrier after this write so 2193 * that this buffer and all buffers written before it are committed to 2194 * the disk before any buffers written after this write are committed 2195 * to the disk. The buffer is released when the output completes. 2196 */ 2197 void 2198 babarrierwrite(struct buf *bp) 2199 { 2200 2201 bp->b_flags |= B_ASYNC | B_BARRIER; 2202 (void) bwrite(bp); 2203 } 2204 2205 /* 2206 * bbarrierwrite: 2207 * 2208 * Synchronous barrier write. Start output on a buffer and wait for 2209 * it to complete. Place a write barrier after this write so that 2210 * this buffer and all buffers written before it are committed to 2211 * the disk before any buffers written after this write are committed 2212 * to the disk. The buffer is released when the output completes. 2213 */ 2214 int 2215 bbarrierwrite(struct buf *bp) 2216 { 2217 2218 bp->b_flags |= B_BARRIER; 2219 return (bwrite(bp)); 2220 } 2221 2222 /* 2223 * bwillwrite: 2224 * 2225 * Called prior to the locking of any vnodes when we are expecting to 2226 * write. We do not want to starve the buffer cache with too many 2227 * dirty buffers so we block here. By blocking prior to the locking 2228 * of any vnodes we attempt to avoid the situation where a locked vnode 2229 * prevents the various system daemons from flushing related buffers. 2230 */ 2231 void 2232 bwillwrite(void) 2233 { 2234 2235 if (numdirtybuffers >= hidirtybuffers) { 2236 mtx_lock(&bdirtylock); 2237 while (numdirtybuffers >= hidirtybuffers) { 2238 bdirtywait = 1; 2239 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4), 2240 "flswai", 0); 2241 } 2242 mtx_unlock(&bdirtylock); 2243 } 2244 } 2245 2246 /* 2247 * Return true if we have too many dirty buffers. 2248 */ 2249 int 2250 buf_dirty_count_severe(void) 2251 { 2252 2253 return(numdirtybuffers >= hidirtybuffers); 2254 } 2255 2256 /* 2257 * brelse: 2258 * 2259 * Release a busy buffer and, if requested, free its resources. The 2260 * buffer will be stashed in the appropriate bufqueue[] allowing it 2261 * to be accessed later as a cache entity or reused for other purposes. 2262 */ 2263 void 2264 brelse(struct buf *bp) 2265 { 2266 int qindex; 2267 2268 /* 2269 * Many functions erroneously call brelse with a NULL bp under rare 2270 * error conditions. Simply return when called with a NULL bp. 2271 */ 2272 if (bp == NULL) 2273 return; 2274 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 2275 bp, bp->b_vp, bp->b_flags); 2276 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 2277 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 2278 KASSERT((bp->b_flags & B_VMIO) != 0 || (bp->b_flags & B_NOREUSE) == 0, 2279 ("brelse: non-VMIO buffer marked NOREUSE")); 2280 2281 if (BUF_LOCKRECURSED(bp)) { 2282 /* 2283 * Do not process, in particular, do not handle the 2284 * B_INVAL/B_RELBUF and do not release to free list. 2285 */ 2286 BUF_UNLOCK(bp); 2287 return; 2288 } 2289 2290 if (bp->b_flags & B_MANAGED) { 2291 bqrelse(bp); 2292 return; 2293 } 2294 2295 if ((bp->b_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) { 2296 BO_LOCK(bp->b_bufobj); 2297 bp->b_vflags &= ~BV_BKGRDERR; 2298 BO_UNLOCK(bp->b_bufobj); 2299 bdirty(bp); 2300 } 2301 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 2302 !(bp->b_flags & B_INVAL)) { 2303 /* 2304 * Failed write, redirty. Must clear BIO_ERROR to prevent 2305 * pages from being scrapped. 2306 */ 2307 bp->b_ioflags &= ~BIO_ERROR; 2308 bdirty(bp); 2309 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 2310 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 2311 /* 2312 * Either a failed read I/O or we were asked to free or not 2313 * cache the buffer. 2314 */ 2315 bp->b_flags |= B_INVAL; 2316 if (!LIST_EMPTY(&bp->b_dep)) 2317 buf_deallocate(bp); 2318 if (bp->b_flags & B_DELWRI) 2319 bdirtysub(); 2320 bp->b_flags &= ~(B_DELWRI | B_CACHE); 2321 if ((bp->b_flags & B_VMIO) == 0) { 2322 allocbuf(bp, 0); 2323 if (bp->b_vp) 2324 brelvp(bp); 2325 } 2326 } 2327 2328 /* 2329 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_truncate() 2330 * is called with B_DELWRI set, the underlying pages may wind up 2331 * getting freed causing a previous write (bdwrite()) to get 'lost' 2332 * because pages associated with a B_DELWRI bp are marked clean. 2333 * 2334 * We still allow the B_INVAL case to call vfs_vmio_truncate(), even 2335 * if B_DELWRI is set. 2336 */ 2337 if (bp->b_flags & B_DELWRI) 2338 bp->b_flags &= ~B_RELBUF; 2339 2340 /* 2341 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 2342 * constituted, not even NFS buffers now. Two flags effect this. If 2343 * B_INVAL, the struct buf is invalidated but the VM object is kept 2344 * around ( i.e. so it is trivial to reconstitute the buffer later ). 2345 * 2346 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 2347 * invalidated. BIO_ERROR cannot be set for a failed write unless the 2348 * buffer is also B_INVAL because it hits the re-dirtying code above. 2349 * 2350 * Normally we can do this whether a buffer is B_DELWRI or not. If 2351 * the buffer is an NFS buffer, it is tracking piecemeal writes or 2352 * the commit state and we cannot afford to lose the buffer. If the 2353 * buffer has a background write in progress, we need to keep it 2354 * around to prevent it from being reconstituted and starting a second 2355 * background write. 2356 */ 2357 if ((bp->b_flags & B_VMIO) && (bp->b_flags & B_NOCACHE || 2358 (bp->b_ioflags & BIO_ERROR && bp->b_iocmd == BIO_READ)) && 2359 !(bp->b_vp->v_mount != NULL && 2360 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 2361 !vn_isdisk(bp->b_vp, NULL) && (bp->b_flags & B_DELWRI))) { 2362 vfs_vmio_invalidate(bp); 2363 allocbuf(bp, 0); 2364 } 2365 2366 if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0 || 2367 (bp->b_flags & (B_DELWRI | B_NOREUSE)) == B_NOREUSE) { 2368 allocbuf(bp, 0); 2369 bp->b_flags &= ~B_NOREUSE; 2370 if (bp->b_vp != NULL) 2371 brelvp(bp); 2372 } 2373 2374 /* 2375 * If the buffer has junk contents signal it and eventually 2376 * clean up B_DELWRI and diassociate the vnode so that gbincore() 2377 * doesn't find it. 2378 */ 2379 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 2380 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 2381 bp->b_flags |= B_INVAL; 2382 if (bp->b_flags & B_INVAL) { 2383 if (bp->b_flags & B_DELWRI) 2384 bundirty(bp); 2385 if (bp->b_vp) 2386 brelvp(bp); 2387 } 2388 2389 /* buffers with no memory */ 2390 if (bp->b_bufsize == 0) { 2391 buf_free(bp); 2392 return; 2393 } 2394 /* buffers with junk contents */ 2395 if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 2396 (bp->b_ioflags & BIO_ERROR)) { 2397 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 2398 if (bp->b_vflags & BV_BKGRDINPROG) 2399 panic("losing buffer 2"); 2400 qindex = QUEUE_CLEAN; 2401 bp->b_flags |= B_AGE; 2402 /* remaining buffers */ 2403 } else if (bp->b_flags & B_DELWRI) 2404 qindex = QUEUE_DIRTY; 2405 else 2406 qindex = QUEUE_CLEAN; 2407 2408 binsfree(bp, qindex); 2409 2410 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 2411 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 2412 panic("brelse: not dirty"); 2413 /* unlock */ 2414 BUF_UNLOCK(bp); 2415 if (qindex == QUEUE_CLEAN) 2416 bufspace_wakeup(); 2417 } 2418 2419 /* 2420 * Release a buffer back to the appropriate queue but do not try to free 2421 * it. The buffer is expected to be used again soon. 2422 * 2423 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 2424 * biodone() to requeue an async I/O on completion. It is also used when 2425 * known good buffers need to be requeued but we think we may need the data 2426 * again soon. 2427 * 2428 * XXX we should be able to leave the B_RELBUF hint set on completion. 2429 */ 2430 void 2431 bqrelse(struct buf *bp) 2432 { 2433 int qindex; 2434 2435 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2436 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 2437 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 2438 2439 qindex = QUEUE_NONE; 2440 if (BUF_LOCKRECURSED(bp)) { 2441 /* do not release to free list */ 2442 BUF_UNLOCK(bp); 2443 return; 2444 } 2445 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 2446 2447 if (bp->b_flags & B_MANAGED) { 2448 if (bp->b_flags & B_REMFREE) 2449 bremfreef(bp); 2450 goto out; 2451 } 2452 2453 /* buffers with stale but valid contents */ 2454 if ((bp->b_flags & B_DELWRI) != 0 || (bp->b_vflags & (BV_BKGRDINPROG | 2455 BV_BKGRDERR)) == BV_BKGRDERR) { 2456 BO_LOCK(bp->b_bufobj); 2457 bp->b_vflags &= ~BV_BKGRDERR; 2458 BO_UNLOCK(bp->b_bufobj); 2459 qindex = QUEUE_DIRTY; 2460 } else { 2461 if ((bp->b_flags & B_DELWRI) == 0 && 2462 (bp->b_xflags & BX_VNDIRTY)) 2463 panic("bqrelse: not dirty"); 2464 if ((bp->b_flags & B_NOREUSE) != 0) { 2465 brelse(bp); 2466 return; 2467 } 2468 qindex = QUEUE_CLEAN; 2469 } 2470 binsfree(bp, qindex); 2471 2472 out: 2473 /* unlock */ 2474 BUF_UNLOCK(bp); 2475 if (qindex == QUEUE_CLEAN) 2476 bufspace_wakeup(); 2477 } 2478 2479 /* 2480 * Complete I/O to a VMIO backed page. Validate the pages as appropriate, 2481 * restore bogus pages. 2482 */ 2483 static void 2484 vfs_vmio_iodone(struct buf *bp) 2485 { 2486 vm_ooffset_t foff; 2487 vm_page_t m; 2488 vm_object_t obj; 2489 struct vnode *vp; 2490 int bogus, i, iosize; 2491 2492 obj = bp->b_bufobj->bo_object; 2493 KASSERT(obj->paging_in_progress >= bp->b_npages, 2494 ("vfs_vmio_iodone: paging in progress(%d) < b_npages(%d)", 2495 obj->paging_in_progress, bp->b_npages)); 2496 2497 vp = bp->b_vp; 2498 KASSERT(vp->v_holdcnt > 0, 2499 ("vfs_vmio_iodone: vnode %p has zero hold count", vp)); 2500 KASSERT(vp->v_object != NULL, 2501 ("vfs_vmio_iodone: vnode %p has no vm_object", vp)); 2502 2503 foff = bp->b_offset; 2504 KASSERT(bp->b_offset != NOOFFSET, 2505 ("vfs_vmio_iodone: bp %p has no buffer offset", bp)); 2506 2507 bogus = 0; 2508 iosize = bp->b_bcount - bp->b_resid; 2509 VM_OBJECT_WLOCK(obj); 2510 for (i = 0; i < bp->b_npages; i++) { 2511 int resid; 2512 2513 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 2514 if (resid > iosize) 2515 resid = iosize; 2516 2517 /* 2518 * cleanup bogus pages, restoring the originals 2519 */ 2520 m = bp->b_pages[i]; 2521 if (m == bogus_page) { 2522 bogus = 1; 2523 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 2524 if (m == NULL) 2525 panic("biodone: page disappeared!"); 2526 bp->b_pages[i] = m; 2527 } else if ((bp->b_iocmd == BIO_READ) && resid > 0) { 2528 /* 2529 * In the write case, the valid and clean bits are 2530 * already changed correctly ( see bdwrite() ), so we 2531 * only need to do this here in the read case. 2532 */ 2533 KASSERT((m->dirty & vm_page_bits(foff & PAGE_MASK, 2534 resid)) == 0, ("vfs_vmio_iodone: page %p " 2535 "has unexpected dirty bits", m)); 2536 vfs_page_set_valid(bp, foff, m); 2537 } 2538 KASSERT(OFF_TO_IDX(foff) == m->pindex, 2539 ("vfs_vmio_iodone: foff(%jd)/pindex(%ju) mismatch", 2540 (intmax_t)foff, (uintmax_t)m->pindex)); 2541 2542 vm_page_sunbusy(m); 2543 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2544 iosize -= resid; 2545 } 2546 vm_object_pip_wakeupn(obj, bp->b_npages); 2547 VM_OBJECT_WUNLOCK(obj); 2548 if (bogus && buf_mapped(bp)) { 2549 BUF_CHECK_MAPPED(bp); 2550 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 2551 bp->b_pages, bp->b_npages); 2552 } 2553 } 2554 2555 /* 2556 * Unwire a page held by a buf and place it on the appropriate vm queue. 2557 */ 2558 static void 2559 vfs_vmio_unwire(struct buf *bp, vm_page_t m) 2560 { 2561 bool freed; 2562 2563 vm_page_lock(m); 2564 if (vm_page_unwire(m, PQ_NONE)) { 2565 /* 2566 * Determine if the page should be freed before adding 2567 * it to the inactive queue. 2568 */ 2569 if (m->valid == 0) { 2570 freed = !vm_page_busied(m); 2571 if (freed) 2572 vm_page_free(m); 2573 } else if ((bp->b_flags & B_DIRECT) != 0) 2574 freed = vm_page_try_to_free(m); 2575 else 2576 freed = false; 2577 if (!freed) { 2578 /* 2579 * If the page is unlikely to be reused, let the 2580 * VM know. Otherwise, maintain LRU page 2581 * ordering and put the page at the tail of the 2582 * inactive queue. 2583 */ 2584 if ((bp->b_flags & B_NOREUSE) != 0) 2585 vm_page_deactivate_noreuse(m); 2586 else 2587 vm_page_deactivate(m); 2588 } 2589 } 2590 vm_page_unlock(m); 2591 } 2592 2593 /* 2594 * Perform page invalidation when a buffer is released. The fully invalid 2595 * pages will be reclaimed later in vfs_vmio_truncate(). 2596 */ 2597 static void 2598 vfs_vmio_invalidate(struct buf *bp) 2599 { 2600 vm_object_t obj; 2601 vm_page_t m; 2602 int i, resid, poffset, presid; 2603 2604 if (buf_mapped(bp)) { 2605 BUF_CHECK_MAPPED(bp); 2606 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages); 2607 } else 2608 BUF_CHECK_UNMAPPED(bp); 2609 /* 2610 * Get the base offset and length of the buffer. Note that 2611 * in the VMIO case if the buffer block size is not 2612 * page-aligned then b_data pointer may not be page-aligned. 2613 * But our b_pages[] array *IS* page aligned. 2614 * 2615 * block sizes less then DEV_BSIZE (usually 512) are not 2616 * supported due to the page granularity bits (m->valid, 2617 * m->dirty, etc...). 2618 * 2619 * See man buf(9) for more information 2620 */ 2621 obj = bp->b_bufobj->bo_object; 2622 resid = bp->b_bufsize; 2623 poffset = bp->b_offset & PAGE_MASK; 2624 VM_OBJECT_WLOCK(obj); 2625 for (i = 0; i < bp->b_npages; i++) { 2626 m = bp->b_pages[i]; 2627 if (m == bogus_page) 2628 panic("vfs_vmio_invalidate: Unexpected bogus page."); 2629 bp->b_pages[i] = NULL; 2630 2631 presid = resid > (PAGE_SIZE - poffset) ? 2632 (PAGE_SIZE - poffset) : resid; 2633 KASSERT(presid >= 0, ("brelse: extra page")); 2634 while (vm_page_xbusied(m)) { 2635 vm_page_lock(m); 2636 VM_OBJECT_WUNLOCK(obj); 2637 vm_page_busy_sleep(m, "mbncsh", true); 2638 VM_OBJECT_WLOCK(obj); 2639 } 2640 if (pmap_page_wired_mappings(m) == 0) 2641 vm_page_set_invalid(m, poffset, presid); 2642 vfs_vmio_unwire(bp, m); 2643 resid -= presid; 2644 poffset = 0; 2645 } 2646 VM_OBJECT_WUNLOCK(obj); 2647 bp->b_npages = 0; 2648 } 2649 2650 /* 2651 * Page-granular truncation of an existing VMIO buffer. 2652 */ 2653 static void 2654 vfs_vmio_truncate(struct buf *bp, int desiredpages) 2655 { 2656 vm_object_t obj; 2657 vm_page_t m; 2658 int i; 2659 2660 if (bp->b_npages == desiredpages) 2661 return; 2662 2663 if (buf_mapped(bp)) { 2664 BUF_CHECK_MAPPED(bp); 2665 pmap_qremove((vm_offset_t)trunc_page((vm_offset_t)bp->b_data) + 2666 (desiredpages << PAGE_SHIFT), bp->b_npages - desiredpages); 2667 } else 2668 BUF_CHECK_UNMAPPED(bp); 2669 obj = bp->b_bufobj->bo_object; 2670 if (obj != NULL) 2671 VM_OBJECT_WLOCK(obj); 2672 for (i = desiredpages; i < bp->b_npages; i++) { 2673 m = bp->b_pages[i]; 2674 KASSERT(m != bogus_page, ("allocbuf: bogus page found")); 2675 bp->b_pages[i] = NULL; 2676 vfs_vmio_unwire(bp, m); 2677 } 2678 if (obj != NULL) 2679 VM_OBJECT_WUNLOCK(obj); 2680 bp->b_npages = desiredpages; 2681 } 2682 2683 /* 2684 * Byte granular extension of VMIO buffers. 2685 */ 2686 static void 2687 vfs_vmio_extend(struct buf *bp, int desiredpages, int size) 2688 { 2689 /* 2690 * We are growing the buffer, possibly in a 2691 * byte-granular fashion. 2692 */ 2693 vm_object_t obj; 2694 vm_offset_t toff; 2695 vm_offset_t tinc; 2696 vm_page_t m; 2697 2698 /* 2699 * Step 1, bring in the VM pages from the object, allocating 2700 * them if necessary. We must clear B_CACHE if these pages 2701 * are not valid for the range covered by the buffer. 2702 */ 2703 obj = bp->b_bufobj->bo_object; 2704 VM_OBJECT_WLOCK(obj); 2705 while (bp->b_npages < desiredpages) { 2706 /* 2707 * We must allocate system pages since blocking 2708 * here could interfere with paging I/O, no 2709 * matter which process we are. 2710 * 2711 * Only exclusive busy can be tested here. 2712 * Blocking on shared busy might lead to 2713 * deadlocks once allocbuf() is called after 2714 * pages are vfs_busy_pages(). 2715 */ 2716 m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) + bp->b_npages, 2717 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM | 2718 VM_ALLOC_WIRED | VM_ALLOC_IGN_SBUSY | 2719 VM_ALLOC_COUNT(desiredpages - bp->b_npages)); 2720 if (m->valid == 0) 2721 bp->b_flags &= ~B_CACHE; 2722 bp->b_pages[bp->b_npages] = m; 2723 ++bp->b_npages; 2724 } 2725 2726 /* 2727 * Step 2. We've loaded the pages into the buffer, 2728 * we have to figure out if we can still have B_CACHE 2729 * set. Note that B_CACHE is set according to the 2730 * byte-granular range ( bcount and size ), not the 2731 * aligned range ( newbsize ). 2732 * 2733 * The VM test is against m->valid, which is DEV_BSIZE 2734 * aligned. Needless to say, the validity of the data 2735 * needs to also be DEV_BSIZE aligned. Note that this 2736 * fails with NFS if the server or some other client 2737 * extends the file's EOF. If our buffer is resized, 2738 * B_CACHE may remain set! XXX 2739 */ 2740 toff = bp->b_bcount; 2741 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 2742 while ((bp->b_flags & B_CACHE) && toff < size) { 2743 vm_pindex_t pi; 2744 2745 if (tinc > (size - toff)) 2746 tinc = size - toff; 2747 pi = ((bp->b_offset & PAGE_MASK) + toff) >> PAGE_SHIFT; 2748 m = bp->b_pages[pi]; 2749 vfs_buf_test_cache(bp, bp->b_offset, toff, tinc, m); 2750 toff += tinc; 2751 tinc = PAGE_SIZE; 2752 } 2753 VM_OBJECT_WUNLOCK(obj); 2754 2755 /* 2756 * Step 3, fixup the KVA pmap. 2757 */ 2758 if (buf_mapped(bp)) 2759 bpmap_qenter(bp); 2760 else 2761 BUF_CHECK_UNMAPPED(bp); 2762 } 2763 2764 /* 2765 * Check to see if a block at a particular lbn is available for a clustered 2766 * write. 2767 */ 2768 static int 2769 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 2770 { 2771 struct buf *bpa; 2772 int match; 2773 2774 match = 0; 2775 2776 /* If the buf isn't in core skip it */ 2777 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 2778 return (0); 2779 2780 /* If the buf is busy we don't want to wait for it */ 2781 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2782 return (0); 2783 2784 /* Only cluster with valid clusterable delayed write buffers */ 2785 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 2786 (B_DELWRI | B_CLUSTEROK)) 2787 goto done; 2788 2789 if (bpa->b_bufsize != size) 2790 goto done; 2791 2792 /* 2793 * Check to see if it is in the expected place on disk and that the 2794 * block has been mapped. 2795 */ 2796 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 2797 match = 1; 2798 done: 2799 BUF_UNLOCK(bpa); 2800 return (match); 2801 } 2802 2803 /* 2804 * vfs_bio_awrite: 2805 * 2806 * Implement clustered async writes for clearing out B_DELWRI buffers. 2807 * This is much better then the old way of writing only one buffer at 2808 * a time. Note that we may not be presented with the buffers in the 2809 * correct order, so we search for the cluster in both directions. 2810 */ 2811 int 2812 vfs_bio_awrite(struct buf *bp) 2813 { 2814 struct bufobj *bo; 2815 int i; 2816 int j; 2817 daddr_t lblkno = bp->b_lblkno; 2818 struct vnode *vp = bp->b_vp; 2819 int ncl; 2820 int nwritten; 2821 int size; 2822 int maxcl; 2823 int gbflags; 2824 2825 bo = &vp->v_bufobj; 2826 gbflags = (bp->b_data == unmapped_buf) ? GB_UNMAPPED : 0; 2827 /* 2828 * right now we support clustered writing only to regular files. If 2829 * we find a clusterable block we could be in the middle of a cluster 2830 * rather then at the beginning. 2831 */ 2832 if ((vp->v_type == VREG) && 2833 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 2834 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 2835 2836 size = vp->v_mount->mnt_stat.f_iosize; 2837 maxcl = MAXPHYS / size; 2838 2839 BO_RLOCK(bo); 2840 for (i = 1; i < maxcl; i++) 2841 if (vfs_bio_clcheck(vp, size, lblkno + i, 2842 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 2843 break; 2844 2845 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 2846 if (vfs_bio_clcheck(vp, size, lblkno - j, 2847 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 2848 break; 2849 BO_RUNLOCK(bo); 2850 --j; 2851 ncl = i + j; 2852 /* 2853 * this is a possible cluster write 2854 */ 2855 if (ncl != 1) { 2856 BUF_UNLOCK(bp); 2857 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl, 2858 gbflags); 2859 return (nwritten); 2860 } 2861 } 2862 bremfree(bp); 2863 bp->b_flags |= B_ASYNC; 2864 /* 2865 * default (old) behavior, writing out only one block 2866 * 2867 * XXX returns b_bufsize instead of b_bcount for nwritten? 2868 */ 2869 nwritten = bp->b_bufsize; 2870 (void) bwrite(bp); 2871 2872 return (nwritten); 2873 } 2874 2875 /* 2876 * getnewbuf_kva: 2877 * 2878 * Allocate KVA for an empty buf header according to gbflags. 2879 */ 2880 static int 2881 getnewbuf_kva(struct buf *bp, int gbflags, int maxsize) 2882 { 2883 2884 if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_UNMAPPED) { 2885 /* 2886 * In order to keep fragmentation sane we only allocate kva 2887 * in BKVASIZE chunks. XXX with vmem we can do page size. 2888 */ 2889 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2890 2891 if (maxsize != bp->b_kvasize && 2892 bufkva_alloc(bp, maxsize, gbflags)) 2893 return (ENOSPC); 2894 } 2895 return (0); 2896 } 2897 2898 /* 2899 * getnewbuf: 2900 * 2901 * Find and initialize a new buffer header, freeing up existing buffers 2902 * in the bufqueues as necessary. The new buffer is returned locked. 2903 * 2904 * We block if: 2905 * We have insufficient buffer headers 2906 * We have insufficient buffer space 2907 * buffer_arena is too fragmented ( space reservation fails ) 2908 * If we have to flush dirty buffers ( but we try to avoid this ) 2909 * 2910 * The caller is responsible for releasing the reserved bufspace after 2911 * allocbuf() is called. 2912 */ 2913 static struct buf * 2914 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int maxsize, int gbflags) 2915 { 2916 struct buf *bp; 2917 bool metadata, reserved; 2918 2919 bp = NULL; 2920 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 2921 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 2922 if (!unmapped_buf_allowed) 2923 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC); 2924 2925 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 || 2926 vp->v_type == VCHR) 2927 metadata = true; 2928 else 2929 metadata = false; 2930 atomic_add_int(&getnewbufcalls, 1); 2931 reserved = false; 2932 do { 2933 if (reserved == false && 2934 bufspace_reserve(maxsize, metadata) != 0) 2935 continue; 2936 reserved = true; 2937 if ((bp = buf_alloc()) == NULL) 2938 continue; 2939 if (getnewbuf_kva(bp, gbflags, maxsize) == 0) 2940 return (bp); 2941 break; 2942 } while(buf_scan(false) == 0); 2943 2944 if (reserved) 2945 atomic_subtract_long(&bufspace, maxsize); 2946 if (bp != NULL) { 2947 bp->b_flags |= B_INVAL; 2948 brelse(bp); 2949 } 2950 bufspace_wait(vp, gbflags, slpflag, slptimeo); 2951 2952 return (NULL); 2953 } 2954 2955 /* 2956 * buf_daemon: 2957 * 2958 * buffer flushing daemon. Buffers are normally flushed by the 2959 * update daemon but if it cannot keep up this process starts to 2960 * take the load in an attempt to prevent getnewbuf() from blocking. 2961 */ 2962 static struct kproc_desc buf_kp = { 2963 "bufdaemon", 2964 buf_daemon, 2965 &bufdaemonproc 2966 }; 2967 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 2968 2969 static int 2970 buf_flush(struct vnode *vp, int target) 2971 { 2972 int flushed; 2973 2974 flushed = flushbufqueues(vp, target, 0); 2975 if (flushed == 0) { 2976 /* 2977 * Could not find any buffers without rollback 2978 * dependencies, so just write the first one 2979 * in the hopes of eventually making progress. 2980 */ 2981 if (vp != NULL && target > 2) 2982 target /= 2; 2983 flushbufqueues(vp, target, 1); 2984 } 2985 return (flushed); 2986 } 2987 2988 static void 2989 buf_daemon() 2990 { 2991 int lodirty; 2992 2993 /* 2994 * This process needs to be suspended prior to shutdown sync. 2995 */ 2996 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2997 SHUTDOWN_PRI_LAST); 2998 2999 /* 3000 * This process is allowed to take the buffer cache to the limit 3001 */ 3002 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 3003 mtx_lock(&bdlock); 3004 for (;;) { 3005 bd_request = 0; 3006 mtx_unlock(&bdlock); 3007 3008 kproc_suspend_check(bufdaemonproc); 3009 lodirty = lodirtybuffers; 3010 if (bd_speedupreq) { 3011 lodirty = numdirtybuffers / 2; 3012 bd_speedupreq = 0; 3013 } 3014 /* 3015 * Do the flush. Limit the amount of in-transit I/O we 3016 * allow to build up, otherwise we would completely saturate 3017 * the I/O system. 3018 */ 3019 while (numdirtybuffers > lodirty) { 3020 if (buf_flush(NULL, numdirtybuffers - lodirty) == 0) 3021 break; 3022 kern_yield(PRI_USER); 3023 } 3024 3025 /* 3026 * Only clear bd_request if we have reached our low water 3027 * mark. The buf_daemon normally waits 1 second and 3028 * then incrementally flushes any dirty buffers that have 3029 * built up, within reason. 3030 * 3031 * If we were unable to hit our low water mark and couldn't 3032 * find any flushable buffers, we sleep for a short period 3033 * to avoid endless loops on unlockable buffers. 3034 */ 3035 mtx_lock(&bdlock); 3036 if (numdirtybuffers <= lodirtybuffers) { 3037 /* 3038 * We reached our low water mark, reset the 3039 * request and sleep until we are needed again. 3040 * The sleep is just so the suspend code works. 3041 */ 3042 bd_request = 0; 3043 /* 3044 * Do an extra wakeup in case dirty threshold 3045 * changed via sysctl and the explicit transition 3046 * out of shortfall was missed. 3047 */ 3048 bdirtywakeup(); 3049 if (runningbufspace <= lorunningspace) 3050 runningwakeup(); 3051 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 3052 } else { 3053 /* 3054 * We couldn't find any flushable dirty buffers but 3055 * still have too many dirty buffers, we 3056 * have to sleep and try again. (rare) 3057 */ 3058 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 3059 } 3060 } 3061 } 3062 3063 /* 3064 * flushbufqueues: 3065 * 3066 * Try to flush a buffer in the dirty queue. We must be careful to 3067 * free up B_INVAL buffers instead of write them, which NFS is 3068 * particularly sensitive to. 3069 */ 3070 static int flushwithdeps = 0; 3071 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 3072 0, "Number of buffers flushed with dependecies that require rollbacks"); 3073 3074 static int 3075 flushbufqueues(struct vnode *lvp, int target, int flushdeps) 3076 { 3077 struct buf *sentinel; 3078 struct vnode *vp; 3079 struct mount *mp; 3080 struct buf *bp; 3081 int hasdeps; 3082 int flushed; 3083 int queue; 3084 int error; 3085 bool unlock; 3086 3087 flushed = 0; 3088 queue = QUEUE_DIRTY; 3089 bp = NULL; 3090 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 3091 sentinel->b_qindex = QUEUE_SENTINEL; 3092 mtx_lock(&bqlocks[queue]); 3093 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist); 3094 mtx_unlock(&bqlocks[queue]); 3095 while (flushed != target) { 3096 maybe_yield(); 3097 mtx_lock(&bqlocks[queue]); 3098 bp = TAILQ_NEXT(sentinel, b_freelist); 3099 if (bp != NULL) { 3100 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 3101 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel, 3102 b_freelist); 3103 } else { 3104 mtx_unlock(&bqlocks[queue]); 3105 break; 3106 } 3107 /* 3108 * Skip sentinels inserted by other invocations of the 3109 * flushbufqueues(), taking care to not reorder them. 3110 * 3111 * Only flush the buffers that belong to the 3112 * vnode locked by the curthread. 3113 */ 3114 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL && 3115 bp->b_vp != lvp)) { 3116 mtx_unlock(&bqlocks[queue]); 3117 continue; 3118 } 3119 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL); 3120 mtx_unlock(&bqlocks[queue]); 3121 if (error != 0) 3122 continue; 3123 3124 /* 3125 * BKGRDINPROG can only be set with the buf and bufobj 3126 * locks both held. We tolerate a race to clear it here. 3127 */ 3128 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 3129 (bp->b_flags & B_DELWRI) == 0) { 3130 BUF_UNLOCK(bp); 3131 continue; 3132 } 3133 if (bp->b_flags & B_INVAL) { 3134 bremfreef(bp); 3135 brelse(bp); 3136 flushed++; 3137 continue; 3138 } 3139 3140 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 3141 if (flushdeps == 0) { 3142 BUF_UNLOCK(bp); 3143 continue; 3144 } 3145 hasdeps = 1; 3146 } else 3147 hasdeps = 0; 3148 /* 3149 * We must hold the lock on a vnode before writing 3150 * one of its buffers. Otherwise we may confuse, or 3151 * in the case of a snapshot vnode, deadlock the 3152 * system. 3153 * 3154 * The lock order here is the reverse of the normal 3155 * of vnode followed by buf lock. This is ok because 3156 * the NOWAIT will prevent deadlock. 3157 */ 3158 vp = bp->b_vp; 3159 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 3160 BUF_UNLOCK(bp); 3161 continue; 3162 } 3163 if (lvp == NULL) { 3164 unlock = true; 3165 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT); 3166 } else { 3167 ASSERT_VOP_LOCKED(vp, "getbuf"); 3168 unlock = false; 3169 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 : 3170 vn_lock(vp, LK_TRYUPGRADE); 3171 } 3172 if (error == 0) { 3173 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 3174 bp, bp->b_vp, bp->b_flags); 3175 if (curproc == bufdaemonproc) { 3176 vfs_bio_awrite(bp); 3177 } else { 3178 bremfree(bp); 3179 bwrite(bp); 3180 notbufdflushes++; 3181 } 3182 vn_finished_write(mp); 3183 if (unlock) 3184 VOP_UNLOCK(vp, 0); 3185 flushwithdeps += hasdeps; 3186 flushed++; 3187 3188 /* 3189 * Sleeping on runningbufspace while holding 3190 * vnode lock leads to deadlock. 3191 */ 3192 if (curproc == bufdaemonproc && 3193 runningbufspace > hirunningspace) 3194 waitrunningbufspace(); 3195 continue; 3196 } 3197 vn_finished_write(mp); 3198 BUF_UNLOCK(bp); 3199 } 3200 mtx_lock(&bqlocks[queue]); 3201 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 3202 mtx_unlock(&bqlocks[queue]); 3203 free(sentinel, M_TEMP); 3204 return (flushed); 3205 } 3206 3207 /* 3208 * Check to see if a block is currently memory resident. 3209 */ 3210 struct buf * 3211 incore(struct bufobj *bo, daddr_t blkno) 3212 { 3213 struct buf *bp; 3214 3215 BO_RLOCK(bo); 3216 bp = gbincore(bo, blkno); 3217 BO_RUNLOCK(bo); 3218 return (bp); 3219 } 3220 3221 /* 3222 * Returns true if no I/O is needed to access the 3223 * associated VM object. This is like incore except 3224 * it also hunts around in the VM system for the data. 3225 */ 3226 3227 static int 3228 inmem(struct vnode * vp, daddr_t blkno) 3229 { 3230 vm_object_t obj; 3231 vm_offset_t toff, tinc, size; 3232 vm_page_t m; 3233 vm_ooffset_t off; 3234 3235 ASSERT_VOP_LOCKED(vp, "inmem"); 3236 3237 if (incore(&vp->v_bufobj, blkno)) 3238 return 1; 3239 if (vp->v_mount == NULL) 3240 return 0; 3241 obj = vp->v_object; 3242 if (obj == NULL) 3243 return (0); 3244 3245 size = PAGE_SIZE; 3246 if (size > vp->v_mount->mnt_stat.f_iosize) 3247 size = vp->v_mount->mnt_stat.f_iosize; 3248 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 3249 3250 VM_OBJECT_RLOCK(obj); 3251 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 3252 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 3253 if (!m) 3254 goto notinmem; 3255 tinc = size; 3256 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 3257 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 3258 if (vm_page_is_valid(m, 3259 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 3260 goto notinmem; 3261 } 3262 VM_OBJECT_RUNLOCK(obj); 3263 return 1; 3264 3265 notinmem: 3266 VM_OBJECT_RUNLOCK(obj); 3267 return (0); 3268 } 3269 3270 /* 3271 * Set the dirty range for a buffer based on the status of the dirty 3272 * bits in the pages comprising the buffer. The range is limited 3273 * to the size of the buffer. 3274 * 3275 * Tell the VM system that the pages associated with this buffer 3276 * are clean. This is used for delayed writes where the data is 3277 * going to go to disk eventually without additional VM intevention. 3278 * 3279 * Note that while we only really need to clean through to b_bcount, we 3280 * just go ahead and clean through to b_bufsize. 3281 */ 3282 static void 3283 vfs_clean_pages_dirty_buf(struct buf *bp) 3284 { 3285 vm_ooffset_t foff, noff, eoff; 3286 vm_page_t m; 3287 int i; 3288 3289 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 3290 return; 3291 3292 foff = bp->b_offset; 3293 KASSERT(bp->b_offset != NOOFFSET, 3294 ("vfs_clean_pages_dirty_buf: no buffer offset")); 3295 3296 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 3297 vfs_drain_busy_pages(bp); 3298 vfs_setdirty_locked_object(bp); 3299 for (i = 0; i < bp->b_npages; i++) { 3300 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3301 eoff = noff; 3302 if (eoff > bp->b_offset + bp->b_bufsize) 3303 eoff = bp->b_offset + bp->b_bufsize; 3304 m = bp->b_pages[i]; 3305 vfs_page_set_validclean(bp, foff, m); 3306 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3307 foff = noff; 3308 } 3309 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 3310 } 3311 3312 static void 3313 vfs_setdirty_locked_object(struct buf *bp) 3314 { 3315 vm_object_t object; 3316 int i; 3317 3318 object = bp->b_bufobj->bo_object; 3319 VM_OBJECT_ASSERT_WLOCKED(object); 3320 3321 /* 3322 * We qualify the scan for modified pages on whether the 3323 * object has been flushed yet. 3324 */ 3325 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) { 3326 vm_offset_t boffset; 3327 vm_offset_t eoffset; 3328 3329 /* 3330 * test the pages to see if they have been modified directly 3331 * by users through the VM system. 3332 */ 3333 for (i = 0; i < bp->b_npages; i++) 3334 vm_page_test_dirty(bp->b_pages[i]); 3335 3336 /* 3337 * Calculate the encompassing dirty range, boffset and eoffset, 3338 * (eoffset - boffset) bytes. 3339 */ 3340 3341 for (i = 0; i < bp->b_npages; i++) { 3342 if (bp->b_pages[i]->dirty) 3343 break; 3344 } 3345 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3346 3347 for (i = bp->b_npages - 1; i >= 0; --i) { 3348 if (bp->b_pages[i]->dirty) { 3349 break; 3350 } 3351 } 3352 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3353 3354 /* 3355 * Fit it to the buffer. 3356 */ 3357 3358 if (eoffset > bp->b_bcount) 3359 eoffset = bp->b_bcount; 3360 3361 /* 3362 * If we have a good dirty range, merge with the existing 3363 * dirty range. 3364 */ 3365 3366 if (boffset < eoffset) { 3367 if (bp->b_dirtyoff > boffset) 3368 bp->b_dirtyoff = boffset; 3369 if (bp->b_dirtyend < eoffset) 3370 bp->b_dirtyend = eoffset; 3371 } 3372 } 3373 } 3374 3375 /* 3376 * Allocate the KVA mapping for an existing buffer. 3377 * If an unmapped buffer is provided but a mapped buffer is requested, take 3378 * also care to properly setup mappings between pages and KVA. 3379 */ 3380 static void 3381 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags) 3382 { 3383 int bsize, maxsize, need_mapping, need_kva; 3384 off_t offset; 3385 3386 need_mapping = bp->b_data == unmapped_buf && 3387 (gbflags & GB_UNMAPPED) == 0; 3388 need_kva = bp->b_kvabase == unmapped_buf && 3389 bp->b_data == unmapped_buf && 3390 (gbflags & GB_KVAALLOC) != 0; 3391 if (!need_mapping && !need_kva) 3392 return; 3393 3394 BUF_CHECK_UNMAPPED(bp); 3395 3396 if (need_mapping && bp->b_kvabase != unmapped_buf) { 3397 /* 3398 * Buffer is not mapped, but the KVA was already 3399 * reserved at the time of the instantiation. Use the 3400 * allocated space. 3401 */ 3402 goto has_addr; 3403 } 3404 3405 /* 3406 * Calculate the amount of the address space we would reserve 3407 * if the buffer was mapped. 3408 */ 3409 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize; 3410 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3411 offset = blkno * bsize; 3412 maxsize = size + (offset & PAGE_MASK); 3413 maxsize = imax(maxsize, bsize); 3414 3415 while (bufkva_alloc(bp, maxsize, gbflags) != 0) { 3416 if ((gbflags & GB_NOWAIT_BD) != 0) { 3417 /* 3418 * XXXKIB: defragmentation cannot 3419 * succeed, not sure what else to do. 3420 */ 3421 panic("GB_NOWAIT_BD and GB_UNMAPPED %p", bp); 3422 } 3423 atomic_add_int(&mappingrestarts, 1); 3424 bufspace_wait(bp->b_vp, gbflags, 0, 0); 3425 } 3426 has_addr: 3427 if (need_mapping) { 3428 /* b_offset is handled by bpmap_qenter. */ 3429 bp->b_data = bp->b_kvabase; 3430 BUF_CHECK_MAPPED(bp); 3431 bpmap_qenter(bp); 3432 } 3433 } 3434 3435 /* 3436 * getblk: 3437 * 3438 * Get a block given a specified block and offset into a file/device. 3439 * The buffers B_DONE bit will be cleared on return, making it almost 3440 * ready for an I/O initiation. B_INVAL may or may not be set on 3441 * return. The caller should clear B_INVAL prior to initiating a 3442 * READ. 3443 * 3444 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 3445 * an existing buffer. 3446 * 3447 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 3448 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 3449 * and then cleared based on the backing VM. If the previous buffer is 3450 * non-0-sized but invalid, B_CACHE will be cleared. 3451 * 3452 * If getblk() must create a new buffer, the new buffer is returned with 3453 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 3454 * case it is returned with B_INVAL clear and B_CACHE set based on the 3455 * backing VM. 3456 * 3457 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 3458 * B_CACHE bit is clear. 3459 * 3460 * What this means, basically, is that the caller should use B_CACHE to 3461 * determine whether the buffer is fully valid or not and should clear 3462 * B_INVAL prior to issuing a read. If the caller intends to validate 3463 * the buffer by loading its data area with something, the caller needs 3464 * to clear B_INVAL. If the caller does this without issuing an I/O, 3465 * the caller should set B_CACHE ( as an optimization ), else the caller 3466 * should issue the I/O and biodone() will set B_CACHE if the I/O was 3467 * a write attempt or if it was a successful read. If the caller 3468 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 3469 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 3470 */ 3471 struct buf * 3472 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3473 int flags) 3474 { 3475 struct buf *bp; 3476 struct bufobj *bo; 3477 int bsize, error, maxsize, vmio; 3478 off_t offset; 3479 3480 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 3481 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3482 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3483 ASSERT_VOP_LOCKED(vp, "getblk"); 3484 if (size > MAXBCACHEBUF) 3485 panic("getblk: size(%d) > MAXBCACHEBUF(%d)\n", size, 3486 MAXBCACHEBUF); 3487 if (!unmapped_buf_allowed) 3488 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3489 3490 bo = &vp->v_bufobj; 3491 loop: 3492 BO_RLOCK(bo); 3493 bp = gbincore(bo, blkno); 3494 if (bp != NULL) { 3495 int lockflags; 3496 /* 3497 * Buffer is in-core. If the buffer is not busy nor managed, 3498 * it must be on a queue. 3499 */ 3500 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 3501 3502 if (flags & GB_LOCK_NOWAIT) 3503 lockflags |= LK_NOWAIT; 3504 3505 error = BUF_TIMELOCK(bp, lockflags, 3506 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo); 3507 3508 /* 3509 * If we slept and got the lock we have to restart in case 3510 * the buffer changed identities. 3511 */ 3512 if (error == ENOLCK) 3513 goto loop; 3514 /* We timed out or were interrupted. */ 3515 else if (error) 3516 return (NULL); 3517 /* If recursed, assume caller knows the rules. */ 3518 else if (BUF_LOCKRECURSED(bp)) 3519 goto end; 3520 3521 /* 3522 * The buffer is locked. B_CACHE is cleared if the buffer is 3523 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 3524 * and for a VMIO buffer B_CACHE is adjusted according to the 3525 * backing VM cache. 3526 */ 3527 if (bp->b_flags & B_INVAL) 3528 bp->b_flags &= ~B_CACHE; 3529 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 3530 bp->b_flags |= B_CACHE; 3531 if (bp->b_flags & B_MANAGED) 3532 MPASS(bp->b_qindex == QUEUE_NONE); 3533 else 3534 bremfree(bp); 3535 3536 /* 3537 * check for size inconsistencies for non-VMIO case. 3538 */ 3539 if (bp->b_bcount != size) { 3540 if ((bp->b_flags & B_VMIO) == 0 || 3541 (size > bp->b_kvasize)) { 3542 if (bp->b_flags & B_DELWRI) { 3543 bp->b_flags |= B_NOCACHE; 3544 bwrite(bp); 3545 } else { 3546 if (LIST_EMPTY(&bp->b_dep)) { 3547 bp->b_flags |= B_RELBUF; 3548 brelse(bp); 3549 } else { 3550 bp->b_flags |= B_NOCACHE; 3551 bwrite(bp); 3552 } 3553 } 3554 goto loop; 3555 } 3556 } 3557 3558 /* 3559 * Handle the case of unmapped buffer which should 3560 * become mapped, or the buffer for which KVA 3561 * reservation is requested. 3562 */ 3563 bp_unmapped_get_kva(bp, blkno, size, flags); 3564 3565 /* 3566 * If the size is inconsistent in the VMIO case, we can resize 3567 * the buffer. This might lead to B_CACHE getting set or 3568 * cleared. If the size has not changed, B_CACHE remains 3569 * unchanged from its previous state. 3570 */ 3571 allocbuf(bp, size); 3572 3573 KASSERT(bp->b_offset != NOOFFSET, 3574 ("getblk: no buffer offset")); 3575 3576 /* 3577 * A buffer with B_DELWRI set and B_CACHE clear must 3578 * be committed before we can return the buffer in 3579 * order to prevent the caller from issuing a read 3580 * ( due to B_CACHE not being set ) and overwriting 3581 * it. 3582 * 3583 * Most callers, including NFS and FFS, need this to 3584 * operate properly either because they assume they 3585 * can issue a read if B_CACHE is not set, or because 3586 * ( for example ) an uncached B_DELWRI might loop due 3587 * to softupdates re-dirtying the buffer. In the latter 3588 * case, B_CACHE is set after the first write completes, 3589 * preventing further loops. 3590 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 3591 * above while extending the buffer, we cannot allow the 3592 * buffer to remain with B_CACHE set after the write 3593 * completes or it will represent a corrupt state. To 3594 * deal with this we set B_NOCACHE to scrap the buffer 3595 * after the write. 3596 * 3597 * We might be able to do something fancy, like setting 3598 * B_CACHE in bwrite() except if B_DELWRI is already set, 3599 * so the below call doesn't set B_CACHE, but that gets real 3600 * confusing. This is much easier. 3601 */ 3602 3603 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 3604 bp->b_flags |= B_NOCACHE; 3605 bwrite(bp); 3606 goto loop; 3607 } 3608 bp->b_flags &= ~B_DONE; 3609 } else { 3610 /* 3611 * Buffer is not in-core, create new buffer. The buffer 3612 * returned by getnewbuf() is locked. Note that the returned 3613 * buffer is also considered valid (not marked B_INVAL). 3614 */ 3615 BO_RUNLOCK(bo); 3616 /* 3617 * If the user does not want us to create the buffer, bail out 3618 * here. 3619 */ 3620 if (flags & GB_NOCREAT) 3621 return NULL; 3622 if (numfreebuffers == 0 && TD_IS_IDLETHREAD(curthread)) 3623 return NULL; 3624 3625 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize; 3626 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3627 offset = blkno * bsize; 3628 vmio = vp->v_object != NULL; 3629 if (vmio) { 3630 maxsize = size + (offset & PAGE_MASK); 3631 } else { 3632 maxsize = size; 3633 /* Do not allow non-VMIO notmapped buffers. */ 3634 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3635 } 3636 maxsize = imax(maxsize, bsize); 3637 3638 bp = getnewbuf(vp, slpflag, slptimeo, maxsize, flags); 3639 if (bp == NULL) { 3640 if (slpflag || slptimeo) 3641 return NULL; 3642 /* 3643 * XXX This is here until the sleep path is diagnosed 3644 * enough to work under very low memory conditions. 3645 * 3646 * There's an issue on low memory, 4BSD+non-preempt 3647 * systems (eg MIPS routers with 32MB RAM) where buffer 3648 * exhaustion occurs without sleeping for buffer 3649 * reclaimation. This just sticks in a loop and 3650 * constantly attempts to allocate a buffer, which 3651 * hits exhaustion and tries to wakeup bufdaemon. 3652 * This never happens because we never yield. 3653 * 3654 * The real solution is to identify and fix these cases 3655 * so we aren't effectively busy-waiting in a loop 3656 * until the reclaimation path has cycles to run. 3657 */ 3658 kern_yield(PRI_USER); 3659 goto loop; 3660 } 3661 3662 /* 3663 * This code is used to make sure that a buffer is not 3664 * created while the getnewbuf routine is blocked. 3665 * This can be a problem whether the vnode is locked or not. 3666 * If the buffer is created out from under us, we have to 3667 * throw away the one we just created. 3668 * 3669 * Note: this must occur before we associate the buffer 3670 * with the vp especially considering limitations in 3671 * the splay tree implementation when dealing with duplicate 3672 * lblkno's. 3673 */ 3674 BO_LOCK(bo); 3675 if (gbincore(bo, blkno)) { 3676 BO_UNLOCK(bo); 3677 bp->b_flags |= B_INVAL; 3678 brelse(bp); 3679 bufspace_release(maxsize); 3680 goto loop; 3681 } 3682 3683 /* 3684 * Insert the buffer into the hash, so that it can 3685 * be found by incore. 3686 */ 3687 bp->b_blkno = bp->b_lblkno = blkno; 3688 bp->b_offset = offset; 3689 bgetvp(vp, bp); 3690 BO_UNLOCK(bo); 3691 3692 /* 3693 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 3694 * buffer size starts out as 0, B_CACHE will be set by 3695 * allocbuf() for the VMIO case prior to it testing the 3696 * backing store for validity. 3697 */ 3698 3699 if (vmio) { 3700 bp->b_flags |= B_VMIO; 3701 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 3702 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 3703 bp, vp->v_object, bp->b_bufobj->bo_object)); 3704 } else { 3705 bp->b_flags &= ~B_VMIO; 3706 KASSERT(bp->b_bufobj->bo_object == NULL, 3707 ("ARGH! has b_bufobj->bo_object %p %p\n", 3708 bp, bp->b_bufobj->bo_object)); 3709 BUF_CHECK_MAPPED(bp); 3710 } 3711 3712 allocbuf(bp, size); 3713 bufspace_release(maxsize); 3714 bp->b_flags &= ~B_DONE; 3715 } 3716 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 3717 BUF_ASSERT_HELD(bp); 3718 end: 3719 KASSERT(bp->b_bufobj == bo, 3720 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 3721 return (bp); 3722 } 3723 3724 /* 3725 * Get an empty, disassociated buffer of given size. The buffer is initially 3726 * set to B_INVAL. 3727 */ 3728 struct buf * 3729 geteblk(int size, int flags) 3730 { 3731 struct buf *bp; 3732 int maxsize; 3733 3734 maxsize = (size + BKVAMASK) & ~BKVAMASK; 3735 while ((bp = getnewbuf(NULL, 0, 0, maxsize, flags)) == NULL) { 3736 if ((flags & GB_NOWAIT_BD) && 3737 (curthread->td_pflags & TDP_BUFNEED) != 0) 3738 return (NULL); 3739 } 3740 allocbuf(bp, size); 3741 bufspace_release(maxsize); 3742 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 3743 BUF_ASSERT_HELD(bp); 3744 return (bp); 3745 } 3746 3747 /* 3748 * Truncate the backing store for a non-vmio buffer. 3749 */ 3750 static void 3751 vfs_nonvmio_truncate(struct buf *bp, int newbsize) 3752 { 3753 3754 if (bp->b_flags & B_MALLOC) { 3755 /* 3756 * malloced buffers are not shrunk 3757 */ 3758 if (newbsize == 0) { 3759 bufmallocadjust(bp, 0); 3760 free(bp->b_data, M_BIOBUF); 3761 bp->b_data = bp->b_kvabase; 3762 bp->b_flags &= ~B_MALLOC; 3763 } 3764 return; 3765 } 3766 vm_hold_free_pages(bp, newbsize); 3767 bufspace_adjust(bp, newbsize); 3768 } 3769 3770 /* 3771 * Extend the backing for a non-VMIO buffer. 3772 */ 3773 static void 3774 vfs_nonvmio_extend(struct buf *bp, int newbsize) 3775 { 3776 caddr_t origbuf; 3777 int origbufsize; 3778 3779 /* 3780 * We only use malloced memory on the first allocation. 3781 * and revert to page-allocated memory when the buffer 3782 * grows. 3783 * 3784 * There is a potential smp race here that could lead 3785 * to bufmallocspace slightly passing the max. It 3786 * is probably extremely rare and not worth worrying 3787 * over. 3788 */ 3789 if (bp->b_bufsize == 0 && newbsize <= PAGE_SIZE/2 && 3790 bufmallocspace < maxbufmallocspace) { 3791 bp->b_data = malloc(newbsize, M_BIOBUF, M_WAITOK); 3792 bp->b_flags |= B_MALLOC; 3793 bufmallocadjust(bp, newbsize); 3794 return; 3795 } 3796 3797 /* 3798 * If the buffer is growing on its other-than-first 3799 * allocation then we revert to the page-allocation 3800 * scheme. 3801 */ 3802 origbuf = NULL; 3803 origbufsize = 0; 3804 if (bp->b_flags & B_MALLOC) { 3805 origbuf = bp->b_data; 3806 origbufsize = bp->b_bufsize; 3807 bp->b_data = bp->b_kvabase; 3808 bufmallocadjust(bp, 0); 3809 bp->b_flags &= ~B_MALLOC; 3810 newbsize = round_page(newbsize); 3811 } 3812 vm_hold_load_pages(bp, (vm_offset_t) bp->b_data + bp->b_bufsize, 3813 (vm_offset_t) bp->b_data + newbsize); 3814 if (origbuf != NULL) { 3815 bcopy(origbuf, bp->b_data, origbufsize); 3816 free(origbuf, M_BIOBUF); 3817 } 3818 bufspace_adjust(bp, newbsize); 3819 } 3820 3821 /* 3822 * This code constitutes the buffer memory from either anonymous system 3823 * memory (in the case of non-VMIO operations) or from an associated 3824 * VM object (in the case of VMIO operations). This code is able to 3825 * resize a buffer up or down. 3826 * 3827 * Note that this code is tricky, and has many complications to resolve 3828 * deadlock or inconsistent data situations. Tread lightly!!! 3829 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 3830 * the caller. Calling this code willy nilly can result in the loss of data. 3831 * 3832 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 3833 * B_CACHE for the non-VMIO case. 3834 */ 3835 int 3836 allocbuf(struct buf *bp, int size) 3837 { 3838 int newbsize; 3839 3840 BUF_ASSERT_HELD(bp); 3841 3842 if (bp->b_bcount == size) 3843 return (1); 3844 3845 if (bp->b_kvasize != 0 && bp->b_kvasize < size) 3846 panic("allocbuf: buffer too small"); 3847 3848 newbsize = roundup2(size, DEV_BSIZE); 3849 if ((bp->b_flags & B_VMIO) == 0) { 3850 if ((bp->b_flags & B_MALLOC) == 0) 3851 newbsize = round_page(newbsize); 3852 /* 3853 * Just get anonymous memory from the kernel. Don't 3854 * mess with B_CACHE. 3855 */ 3856 if (newbsize < bp->b_bufsize) 3857 vfs_nonvmio_truncate(bp, newbsize); 3858 else if (newbsize > bp->b_bufsize) 3859 vfs_nonvmio_extend(bp, newbsize); 3860 } else { 3861 int desiredpages; 3862 3863 desiredpages = (size == 0) ? 0 : 3864 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 3865 3866 if (bp->b_flags & B_MALLOC) 3867 panic("allocbuf: VMIO buffer can't be malloced"); 3868 /* 3869 * Set B_CACHE initially if buffer is 0 length or will become 3870 * 0-length. 3871 */ 3872 if (size == 0 || bp->b_bufsize == 0) 3873 bp->b_flags |= B_CACHE; 3874 3875 if (newbsize < bp->b_bufsize) 3876 vfs_vmio_truncate(bp, desiredpages); 3877 /* XXX This looks as if it should be newbsize > b_bufsize */ 3878 else if (size > bp->b_bcount) 3879 vfs_vmio_extend(bp, desiredpages, size); 3880 bufspace_adjust(bp, newbsize); 3881 } 3882 bp->b_bcount = size; /* requested buffer size. */ 3883 return (1); 3884 } 3885 3886 extern int inflight_transient_maps; 3887 3888 void 3889 biodone(struct bio *bp) 3890 { 3891 struct mtx *mtxp; 3892 void (*done)(struct bio *); 3893 vm_offset_t start, end; 3894 3895 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) { 3896 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING; 3897 bp->bio_flags |= BIO_UNMAPPED; 3898 start = trunc_page((vm_offset_t)bp->bio_data); 3899 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length); 3900 bp->bio_data = unmapped_buf; 3901 pmap_qremove(start, OFF_TO_IDX(end - start)); 3902 vmem_free(transient_arena, start, end - start); 3903 atomic_add_int(&inflight_transient_maps, -1); 3904 } 3905 done = bp->bio_done; 3906 if (done == NULL) { 3907 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3908 mtx_lock(mtxp); 3909 bp->bio_flags |= BIO_DONE; 3910 wakeup(bp); 3911 mtx_unlock(mtxp); 3912 } else { 3913 bp->bio_flags |= BIO_DONE; 3914 done(bp); 3915 } 3916 } 3917 3918 /* 3919 * Wait for a BIO to finish. 3920 */ 3921 int 3922 biowait(struct bio *bp, const char *wchan) 3923 { 3924 struct mtx *mtxp; 3925 3926 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3927 mtx_lock(mtxp); 3928 while ((bp->bio_flags & BIO_DONE) == 0) 3929 msleep(bp, mtxp, PRIBIO, wchan, 0); 3930 mtx_unlock(mtxp); 3931 if (bp->bio_error != 0) 3932 return (bp->bio_error); 3933 if (!(bp->bio_flags & BIO_ERROR)) 3934 return (0); 3935 return (EIO); 3936 } 3937 3938 void 3939 biofinish(struct bio *bp, struct devstat *stat, int error) 3940 { 3941 3942 if (error) { 3943 bp->bio_error = error; 3944 bp->bio_flags |= BIO_ERROR; 3945 } 3946 if (stat != NULL) 3947 devstat_end_transaction_bio(stat, bp); 3948 biodone(bp); 3949 } 3950 3951 /* 3952 * bufwait: 3953 * 3954 * Wait for buffer I/O completion, returning error status. The buffer 3955 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3956 * error and cleared. 3957 */ 3958 int 3959 bufwait(struct buf *bp) 3960 { 3961 if (bp->b_iocmd == BIO_READ) 3962 bwait(bp, PRIBIO, "biord"); 3963 else 3964 bwait(bp, PRIBIO, "biowr"); 3965 if (bp->b_flags & B_EINTR) { 3966 bp->b_flags &= ~B_EINTR; 3967 return (EINTR); 3968 } 3969 if (bp->b_ioflags & BIO_ERROR) { 3970 return (bp->b_error ? bp->b_error : EIO); 3971 } else { 3972 return (0); 3973 } 3974 } 3975 3976 /* 3977 * bufdone: 3978 * 3979 * Finish I/O on a buffer, optionally calling a completion function. 3980 * This is usually called from an interrupt so process blocking is 3981 * not allowed. 3982 * 3983 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3984 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3985 * assuming B_INVAL is clear. 3986 * 3987 * For the VMIO case, we set B_CACHE if the op was a read and no 3988 * read error occurred, or if the op was a write. B_CACHE is never 3989 * set if the buffer is invalid or otherwise uncacheable. 3990 * 3991 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3992 * initiator to leave B_INVAL set to brelse the buffer out of existence 3993 * in the biodone routine. 3994 */ 3995 void 3996 bufdone(struct buf *bp) 3997 { 3998 struct bufobj *dropobj; 3999 void (*biodone)(struct buf *); 4000 4001 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 4002 dropobj = NULL; 4003 4004 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 4005 BUF_ASSERT_HELD(bp); 4006 4007 runningbufwakeup(bp); 4008 if (bp->b_iocmd == BIO_WRITE) 4009 dropobj = bp->b_bufobj; 4010 /* call optional completion function if requested */ 4011 if (bp->b_iodone != NULL) { 4012 biodone = bp->b_iodone; 4013 bp->b_iodone = NULL; 4014 (*biodone) (bp); 4015 if (dropobj) 4016 bufobj_wdrop(dropobj); 4017 return; 4018 } 4019 4020 bufdone_finish(bp); 4021 4022 if (dropobj) 4023 bufobj_wdrop(dropobj); 4024 } 4025 4026 void 4027 bufdone_finish(struct buf *bp) 4028 { 4029 BUF_ASSERT_HELD(bp); 4030 4031 if (!LIST_EMPTY(&bp->b_dep)) 4032 buf_complete(bp); 4033 4034 if (bp->b_flags & B_VMIO) { 4035 /* 4036 * Set B_CACHE if the op was a normal read and no error 4037 * occurred. B_CACHE is set for writes in the b*write() 4038 * routines. 4039 */ 4040 if (bp->b_iocmd == BIO_READ && 4041 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 4042 !(bp->b_ioflags & BIO_ERROR)) 4043 bp->b_flags |= B_CACHE; 4044 vfs_vmio_iodone(bp); 4045 } 4046 4047 /* 4048 * For asynchronous completions, release the buffer now. The brelse 4049 * will do a wakeup there if necessary - so no need to do a wakeup 4050 * here in the async case. The sync case always needs to do a wakeup. 4051 */ 4052 if (bp->b_flags & B_ASYNC) { 4053 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || 4054 (bp->b_ioflags & BIO_ERROR)) 4055 brelse(bp); 4056 else 4057 bqrelse(bp); 4058 } else 4059 bdone(bp); 4060 } 4061 4062 /* 4063 * This routine is called in lieu of iodone in the case of 4064 * incomplete I/O. This keeps the busy status for pages 4065 * consistent. 4066 */ 4067 void 4068 vfs_unbusy_pages(struct buf *bp) 4069 { 4070 int i; 4071 vm_object_t obj; 4072 vm_page_t m; 4073 4074 runningbufwakeup(bp); 4075 if (!(bp->b_flags & B_VMIO)) 4076 return; 4077 4078 obj = bp->b_bufobj->bo_object; 4079 VM_OBJECT_WLOCK(obj); 4080 for (i = 0; i < bp->b_npages; i++) { 4081 m = bp->b_pages[i]; 4082 if (m == bogus_page) { 4083 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 4084 if (!m) 4085 panic("vfs_unbusy_pages: page missing\n"); 4086 bp->b_pages[i] = m; 4087 if (buf_mapped(bp)) { 4088 BUF_CHECK_MAPPED(bp); 4089 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4090 bp->b_pages, bp->b_npages); 4091 } else 4092 BUF_CHECK_UNMAPPED(bp); 4093 } 4094 vm_page_sunbusy(m); 4095 } 4096 vm_object_pip_wakeupn(obj, bp->b_npages); 4097 VM_OBJECT_WUNLOCK(obj); 4098 } 4099 4100 /* 4101 * vfs_page_set_valid: 4102 * 4103 * Set the valid bits in a page based on the supplied offset. The 4104 * range is restricted to the buffer's size. 4105 * 4106 * This routine is typically called after a read completes. 4107 */ 4108 static void 4109 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4110 { 4111 vm_ooffset_t eoff; 4112 4113 /* 4114 * Compute the end offset, eoff, such that [off, eoff) does not span a 4115 * page boundary and eoff is not greater than the end of the buffer. 4116 * The end of the buffer, in this case, is our file EOF, not the 4117 * allocation size of the buffer. 4118 */ 4119 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 4120 if (eoff > bp->b_offset + bp->b_bcount) 4121 eoff = bp->b_offset + bp->b_bcount; 4122 4123 /* 4124 * Set valid range. This is typically the entire buffer and thus the 4125 * entire page. 4126 */ 4127 if (eoff > off) 4128 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off); 4129 } 4130 4131 /* 4132 * vfs_page_set_validclean: 4133 * 4134 * Set the valid bits and clear the dirty bits in a page based on the 4135 * supplied offset. The range is restricted to the buffer's size. 4136 */ 4137 static void 4138 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4139 { 4140 vm_ooffset_t soff, eoff; 4141 4142 /* 4143 * Start and end offsets in buffer. eoff - soff may not cross a 4144 * page boundary or cross the end of the buffer. The end of the 4145 * buffer, in this case, is our file EOF, not the allocation size 4146 * of the buffer. 4147 */ 4148 soff = off; 4149 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4150 if (eoff > bp->b_offset + bp->b_bcount) 4151 eoff = bp->b_offset + bp->b_bcount; 4152 4153 /* 4154 * Set valid range. This is typically the entire buffer and thus the 4155 * entire page. 4156 */ 4157 if (eoff > soff) { 4158 vm_page_set_validclean( 4159 m, 4160 (vm_offset_t) (soff & PAGE_MASK), 4161 (vm_offset_t) (eoff - soff) 4162 ); 4163 } 4164 } 4165 4166 /* 4167 * Ensure that all buffer pages are not exclusive busied. If any page is 4168 * exclusive busy, drain it. 4169 */ 4170 void 4171 vfs_drain_busy_pages(struct buf *bp) 4172 { 4173 vm_page_t m; 4174 int i, last_busied; 4175 4176 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object); 4177 last_busied = 0; 4178 for (i = 0; i < bp->b_npages; i++) { 4179 m = bp->b_pages[i]; 4180 if (vm_page_xbusied(m)) { 4181 for (; last_busied < i; last_busied++) 4182 vm_page_sbusy(bp->b_pages[last_busied]); 4183 while (vm_page_xbusied(m)) { 4184 vm_page_lock(m); 4185 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4186 vm_page_busy_sleep(m, "vbpage", true); 4187 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4188 } 4189 } 4190 } 4191 for (i = 0; i < last_busied; i++) 4192 vm_page_sunbusy(bp->b_pages[i]); 4193 } 4194 4195 /* 4196 * This routine is called before a device strategy routine. 4197 * It is used to tell the VM system that paging I/O is in 4198 * progress, and treat the pages associated with the buffer 4199 * almost as being exclusive busy. Also the object paging_in_progress 4200 * flag is handled to make sure that the object doesn't become 4201 * inconsistent. 4202 * 4203 * Since I/O has not been initiated yet, certain buffer flags 4204 * such as BIO_ERROR or B_INVAL may be in an inconsistent state 4205 * and should be ignored. 4206 */ 4207 void 4208 vfs_busy_pages(struct buf *bp, int clear_modify) 4209 { 4210 int i, bogus; 4211 vm_object_t obj; 4212 vm_ooffset_t foff; 4213 vm_page_t m; 4214 4215 if (!(bp->b_flags & B_VMIO)) 4216 return; 4217 4218 obj = bp->b_bufobj->bo_object; 4219 foff = bp->b_offset; 4220 KASSERT(bp->b_offset != NOOFFSET, 4221 ("vfs_busy_pages: no buffer offset")); 4222 VM_OBJECT_WLOCK(obj); 4223 vfs_drain_busy_pages(bp); 4224 if (bp->b_bufsize != 0) 4225 vfs_setdirty_locked_object(bp); 4226 bogus = 0; 4227 for (i = 0; i < bp->b_npages; i++) { 4228 m = bp->b_pages[i]; 4229 4230 if ((bp->b_flags & B_CLUSTER) == 0) { 4231 vm_object_pip_add(obj, 1); 4232 vm_page_sbusy(m); 4233 } 4234 /* 4235 * When readying a buffer for a read ( i.e 4236 * clear_modify == 0 ), it is important to do 4237 * bogus_page replacement for valid pages in 4238 * partially instantiated buffers. Partially 4239 * instantiated buffers can, in turn, occur when 4240 * reconstituting a buffer from its VM backing store 4241 * base. We only have to do this if B_CACHE is 4242 * clear ( which causes the I/O to occur in the 4243 * first place ). The replacement prevents the read 4244 * I/O from overwriting potentially dirty VM-backed 4245 * pages. XXX bogus page replacement is, uh, bogus. 4246 * It may not work properly with small-block devices. 4247 * We need to find a better way. 4248 */ 4249 if (clear_modify) { 4250 pmap_remove_write(m); 4251 vfs_page_set_validclean(bp, foff, m); 4252 } else if (m->valid == VM_PAGE_BITS_ALL && 4253 (bp->b_flags & B_CACHE) == 0) { 4254 bp->b_pages[i] = bogus_page; 4255 bogus++; 4256 } 4257 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4258 } 4259 VM_OBJECT_WUNLOCK(obj); 4260 if (bogus && buf_mapped(bp)) { 4261 BUF_CHECK_MAPPED(bp); 4262 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4263 bp->b_pages, bp->b_npages); 4264 } 4265 } 4266 4267 /* 4268 * vfs_bio_set_valid: 4269 * 4270 * Set the range within the buffer to valid. The range is 4271 * relative to the beginning of the buffer, b_offset. Note that 4272 * b_offset itself may be offset from the beginning of the first 4273 * page. 4274 */ 4275 void 4276 vfs_bio_set_valid(struct buf *bp, int base, int size) 4277 { 4278 int i, n; 4279 vm_page_t m; 4280 4281 if (!(bp->b_flags & B_VMIO)) 4282 return; 4283 4284 /* 4285 * Fixup base to be relative to beginning of first page. 4286 * Set initial n to be the maximum number of bytes in the 4287 * first page that can be validated. 4288 */ 4289 base += (bp->b_offset & PAGE_MASK); 4290 n = PAGE_SIZE - (base & PAGE_MASK); 4291 4292 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4293 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4294 m = bp->b_pages[i]; 4295 if (n > size) 4296 n = size; 4297 vm_page_set_valid_range(m, base & PAGE_MASK, n); 4298 base += n; 4299 size -= n; 4300 n = PAGE_SIZE; 4301 } 4302 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4303 } 4304 4305 /* 4306 * vfs_bio_clrbuf: 4307 * 4308 * If the specified buffer is a non-VMIO buffer, clear the entire 4309 * buffer. If the specified buffer is a VMIO buffer, clear and 4310 * validate only the previously invalid portions of the buffer. 4311 * This routine essentially fakes an I/O, so we need to clear 4312 * BIO_ERROR and B_INVAL. 4313 * 4314 * Note that while we only theoretically need to clear through b_bcount, 4315 * we go ahead and clear through b_bufsize. 4316 */ 4317 void 4318 vfs_bio_clrbuf(struct buf *bp) 4319 { 4320 int i, j, mask, sa, ea, slide; 4321 4322 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 4323 clrbuf(bp); 4324 return; 4325 } 4326 bp->b_flags &= ~B_INVAL; 4327 bp->b_ioflags &= ~BIO_ERROR; 4328 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4329 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 4330 (bp->b_offset & PAGE_MASK) == 0) { 4331 if (bp->b_pages[0] == bogus_page) 4332 goto unlock; 4333 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 4334 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object); 4335 if ((bp->b_pages[0]->valid & mask) == mask) 4336 goto unlock; 4337 if ((bp->b_pages[0]->valid & mask) == 0) { 4338 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize); 4339 bp->b_pages[0]->valid |= mask; 4340 goto unlock; 4341 } 4342 } 4343 sa = bp->b_offset & PAGE_MASK; 4344 slide = 0; 4345 for (i = 0; i < bp->b_npages; i++, sa = 0) { 4346 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize); 4347 ea = slide & PAGE_MASK; 4348 if (ea == 0) 4349 ea = PAGE_SIZE; 4350 if (bp->b_pages[i] == bogus_page) 4351 continue; 4352 j = sa / DEV_BSIZE; 4353 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 4354 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object); 4355 if ((bp->b_pages[i]->valid & mask) == mask) 4356 continue; 4357 if ((bp->b_pages[i]->valid & mask) == 0) 4358 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa); 4359 else { 4360 for (; sa < ea; sa += DEV_BSIZE, j++) { 4361 if ((bp->b_pages[i]->valid & (1 << j)) == 0) { 4362 pmap_zero_page_area(bp->b_pages[i], 4363 sa, DEV_BSIZE); 4364 } 4365 } 4366 } 4367 bp->b_pages[i]->valid |= mask; 4368 } 4369 unlock: 4370 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4371 bp->b_resid = 0; 4372 } 4373 4374 void 4375 vfs_bio_bzero_buf(struct buf *bp, int base, int size) 4376 { 4377 vm_page_t m; 4378 int i, n; 4379 4380 if (buf_mapped(bp)) { 4381 BUF_CHECK_MAPPED(bp); 4382 bzero(bp->b_data + base, size); 4383 } else { 4384 BUF_CHECK_UNMAPPED(bp); 4385 n = PAGE_SIZE - (base & PAGE_MASK); 4386 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4387 m = bp->b_pages[i]; 4388 if (n > size) 4389 n = size; 4390 pmap_zero_page_area(m, base & PAGE_MASK, n); 4391 base += n; 4392 size -= n; 4393 n = PAGE_SIZE; 4394 } 4395 } 4396 } 4397 4398 /* 4399 * vm_hold_load_pages and vm_hold_free_pages get pages into 4400 * a buffers address space. The pages are anonymous and are 4401 * not associated with a file object. 4402 */ 4403 static void 4404 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4405 { 4406 vm_offset_t pg; 4407 vm_page_t p; 4408 int index; 4409 4410 BUF_CHECK_MAPPED(bp); 4411 4412 to = round_page(to); 4413 from = round_page(from); 4414 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4415 4416 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 4417 tryagain: 4418 /* 4419 * note: must allocate system pages since blocking here 4420 * could interfere with paging I/O, no matter which 4421 * process we are. 4422 */ 4423 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ | 4424 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT)); 4425 if (p == NULL) { 4426 VM_WAIT; 4427 goto tryagain; 4428 } 4429 pmap_qenter(pg, &p, 1); 4430 bp->b_pages[index] = p; 4431 } 4432 bp->b_npages = index; 4433 } 4434 4435 /* Return pages associated with this buf to the vm system */ 4436 static void 4437 vm_hold_free_pages(struct buf *bp, int newbsize) 4438 { 4439 vm_offset_t from; 4440 vm_page_t p; 4441 int index, newnpages; 4442 4443 BUF_CHECK_MAPPED(bp); 4444 4445 from = round_page((vm_offset_t)bp->b_data + newbsize); 4446 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4447 if (bp->b_npages > newnpages) 4448 pmap_qremove(from, bp->b_npages - newnpages); 4449 for (index = newnpages; index < bp->b_npages; index++) { 4450 p = bp->b_pages[index]; 4451 bp->b_pages[index] = NULL; 4452 if (vm_page_sbusied(p)) 4453 printf("vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 4454 (intmax_t)bp->b_blkno, (intmax_t)bp->b_lblkno); 4455 p->wire_count--; 4456 vm_page_free(p); 4457 atomic_subtract_int(&vm_cnt.v_wire_count, 1); 4458 } 4459 bp->b_npages = newnpages; 4460 } 4461 4462 /* 4463 * Map an IO request into kernel virtual address space. 4464 * 4465 * All requests are (re)mapped into kernel VA space. 4466 * Notice that we use b_bufsize for the size of the buffer 4467 * to be mapped. b_bcount might be modified by the driver. 4468 * 4469 * Note that even if the caller determines that the address space should 4470 * be valid, a race or a smaller-file mapped into a larger space may 4471 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 4472 * check the return value. 4473 * 4474 * This function only works with pager buffers. 4475 */ 4476 int 4477 vmapbuf(struct buf *bp, int mapbuf) 4478 { 4479 vm_prot_t prot; 4480 int pidx; 4481 4482 if (bp->b_bufsize < 0) 4483 return (-1); 4484 prot = VM_PROT_READ; 4485 if (bp->b_iocmd == BIO_READ) 4486 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 4487 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 4488 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages, 4489 btoc(MAXPHYS))) < 0) 4490 return (-1); 4491 bp->b_npages = pidx; 4492 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK; 4493 if (mapbuf || !unmapped_buf_allowed) { 4494 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_pages, pidx); 4495 bp->b_data = bp->b_kvabase + bp->b_offset; 4496 } else 4497 bp->b_data = unmapped_buf; 4498 return(0); 4499 } 4500 4501 /* 4502 * Free the io map PTEs associated with this IO operation. 4503 * We also invalidate the TLB entries and restore the original b_addr. 4504 * 4505 * This function only works with pager buffers. 4506 */ 4507 void 4508 vunmapbuf(struct buf *bp) 4509 { 4510 int npages; 4511 4512 npages = bp->b_npages; 4513 if (buf_mapped(bp)) 4514 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 4515 vm_page_unhold_pages(bp->b_pages, npages); 4516 4517 bp->b_data = unmapped_buf; 4518 } 4519 4520 void 4521 bdone(struct buf *bp) 4522 { 4523 struct mtx *mtxp; 4524 4525 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4526 mtx_lock(mtxp); 4527 bp->b_flags |= B_DONE; 4528 wakeup(bp); 4529 mtx_unlock(mtxp); 4530 } 4531 4532 void 4533 bwait(struct buf *bp, u_char pri, const char *wchan) 4534 { 4535 struct mtx *mtxp; 4536 4537 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4538 mtx_lock(mtxp); 4539 while ((bp->b_flags & B_DONE) == 0) 4540 msleep(bp, mtxp, pri, wchan, 0); 4541 mtx_unlock(mtxp); 4542 } 4543 4544 int 4545 bufsync(struct bufobj *bo, int waitfor) 4546 { 4547 4548 return (VOP_FSYNC(bo2vnode(bo), waitfor, curthread)); 4549 } 4550 4551 void 4552 bufstrategy(struct bufobj *bo, struct buf *bp) 4553 { 4554 int i = 0; 4555 struct vnode *vp; 4556 4557 vp = bp->b_vp; 4558 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 4559 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 4560 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 4561 i = VOP_STRATEGY(vp, bp); 4562 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 4563 } 4564 4565 void 4566 bufobj_wrefl(struct bufobj *bo) 4567 { 4568 4569 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4570 ASSERT_BO_WLOCKED(bo); 4571 bo->bo_numoutput++; 4572 } 4573 4574 void 4575 bufobj_wref(struct bufobj *bo) 4576 { 4577 4578 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4579 BO_LOCK(bo); 4580 bo->bo_numoutput++; 4581 BO_UNLOCK(bo); 4582 } 4583 4584 void 4585 bufobj_wdrop(struct bufobj *bo) 4586 { 4587 4588 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 4589 BO_LOCK(bo); 4590 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 4591 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 4592 bo->bo_flag &= ~BO_WWAIT; 4593 wakeup(&bo->bo_numoutput); 4594 } 4595 BO_UNLOCK(bo); 4596 } 4597 4598 int 4599 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 4600 { 4601 int error; 4602 4603 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 4604 ASSERT_BO_WLOCKED(bo); 4605 error = 0; 4606 while (bo->bo_numoutput) { 4607 bo->bo_flag |= BO_WWAIT; 4608 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo), 4609 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 4610 if (error) 4611 break; 4612 } 4613 return (error); 4614 } 4615 4616 /* 4617 * Set bio_data or bio_ma for struct bio from the struct buf. 4618 */ 4619 void 4620 bdata2bio(struct buf *bp, struct bio *bip) 4621 { 4622 4623 if (!buf_mapped(bp)) { 4624 KASSERT(unmapped_buf_allowed, ("unmapped")); 4625 bip->bio_ma = bp->b_pages; 4626 bip->bio_ma_n = bp->b_npages; 4627 bip->bio_data = unmapped_buf; 4628 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 4629 bip->bio_flags |= BIO_UNMAPPED; 4630 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) / 4631 PAGE_SIZE == bp->b_npages, 4632 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset, 4633 (long long)bip->bio_length, bip->bio_ma_n)); 4634 } else { 4635 bip->bio_data = bp->b_data; 4636 bip->bio_ma = NULL; 4637 } 4638 } 4639 4640 static int buf_pager_relbuf; 4641 SYSCTL_INT(_vfs, OID_AUTO, buf_pager_relbuf, CTLFLAG_RWTUN, 4642 &buf_pager_relbuf, 0, 4643 "Make buffer pager release buffers after reading"); 4644 4645 /* 4646 * The buffer pager. It uses buffer reads to validate pages. 4647 * 4648 * In contrast to the generic local pager from vm/vnode_pager.c, this 4649 * pager correctly and easily handles volumes where the underlying 4650 * device block size is greater than the machine page size. The 4651 * buffer cache transparently extends the requested page run to be 4652 * aligned at the block boundary, and does the necessary bogus page 4653 * replacements in the addends to avoid obliterating already valid 4654 * pages. 4655 * 4656 * The only non-trivial issue is that the exclusive busy state for 4657 * pages, which is assumed by the vm_pager_getpages() interface, is 4658 * incompatible with the VMIO buffer cache's desire to share-busy the 4659 * pages. This function performs a trivial downgrade of the pages' 4660 * state before reading buffers, and a less trivial upgrade from the 4661 * shared-busy to excl-busy state after the read. 4662 */ 4663 int 4664 vfs_bio_getpages(struct vnode *vp, vm_page_t *ma, int count, 4665 int *rbehind, int *rahead, vbg_get_lblkno_t get_lblkno, 4666 vbg_get_blksize_t get_blksize) 4667 { 4668 vm_page_t m; 4669 vm_object_t object; 4670 struct buf *bp; 4671 daddr_t lbn, lbnp; 4672 vm_ooffset_t la, lb, poff, poffe; 4673 long bsize; 4674 int bo_bs, error, i; 4675 bool redo, lpart; 4676 4677 object = vp->v_object; 4678 la = IDX_TO_OFF(ma[count - 1]->pindex); 4679 if (la >= object->un_pager.vnp.vnp_size) 4680 return (VM_PAGER_BAD); 4681 lpart = la + PAGE_SIZE > object->un_pager.vnp.vnp_size; 4682 bo_bs = get_blksize(vp, get_lblkno(vp, IDX_TO_OFF(ma[0]->pindex))); 4683 if (rbehind != NULL) { 4684 lb = IDX_TO_OFF(ma[0]->pindex); 4685 *rbehind = OFF_TO_IDX(lb - rounddown2(lb, bo_bs)); 4686 } 4687 if (rahead != NULL) { 4688 *rahead = OFF_TO_IDX(roundup2(la, bo_bs) - la); 4689 if (la + IDX_TO_OFF(*rahead) >= object->un_pager.vnp.vnp_size) { 4690 *rahead = OFF_TO_IDX(roundup2(object->un_pager. 4691 vnp.vnp_size, PAGE_SIZE) - la); 4692 } 4693 } 4694 VM_OBJECT_WLOCK(object); 4695 again: 4696 for (i = 0; i < count; i++) 4697 vm_page_busy_downgrade(ma[i]); 4698 VM_OBJECT_WUNLOCK(object); 4699 4700 lbnp = -1; 4701 for (i = 0; i < count; i++) { 4702 m = ma[i]; 4703 4704 /* 4705 * Pages are shared busy and the object lock is not 4706 * owned, which together allow for the pages' 4707 * invalidation. The racy test for validity avoids 4708 * useless creation of the buffer for the most typical 4709 * case when invalidation is not used in redo or for 4710 * parallel read. The shared->excl upgrade loop at 4711 * the end of the function catches the race in a 4712 * reliable way (protected by the object lock). 4713 */ 4714 if (m->valid == VM_PAGE_BITS_ALL) 4715 continue; 4716 4717 poff = IDX_TO_OFF(m->pindex); 4718 poffe = MIN(poff + PAGE_SIZE, object->un_pager.vnp.vnp_size); 4719 for (; poff < poffe; poff += bsize) { 4720 lbn = get_lblkno(vp, poff); 4721 if (lbn == lbnp) 4722 goto next_page; 4723 lbnp = lbn; 4724 4725 bsize = get_blksize(vp, lbn); 4726 error = bread_gb(vp, lbn, bsize, NOCRED, GB_UNMAPPED, 4727 &bp); 4728 if (error != 0) 4729 goto end_pages; 4730 if (LIST_EMPTY(&bp->b_dep)) { 4731 /* 4732 * Invalidation clears m->valid, but 4733 * may leave B_CACHE flag if the 4734 * buffer existed at the invalidation 4735 * time. In this case, recycle the 4736 * buffer to do real read on next 4737 * bread() after redo. 4738 * 4739 * Otherwise B_RELBUF is not strictly 4740 * necessary, enable to reduce buf 4741 * cache pressure. 4742 */ 4743 if (buf_pager_relbuf || 4744 m->valid != VM_PAGE_BITS_ALL) 4745 bp->b_flags |= B_RELBUF; 4746 4747 bp->b_flags &= ~B_NOCACHE; 4748 brelse(bp); 4749 } else { 4750 bqrelse(bp); 4751 } 4752 } 4753 KASSERT(1 /* racy, enable for debugging */ || 4754 m->valid == VM_PAGE_BITS_ALL || i == count - 1, 4755 ("buf %d %p invalid", i, m)); 4756 if (i == count - 1 && lpart) { 4757 VM_OBJECT_WLOCK(object); 4758 if (m->valid != 0 && 4759 m->valid != VM_PAGE_BITS_ALL) 4760 vm_page_zero_invalid(m, TRUE); 4761 VM_OBJECT_WUNLOCK(object); 4762 } 4763 next_page:; 4764 } 4765 end_pages: 4766 4767 VM_OBJECT_WLOCK(object); 4768 redo = false; 4769 for (i = 0; i < count; i++) { 4770 vm_page_sunbusy(ma[i]); 4771 ma[i] = vm_page_grab(object, ma[i]->pindex, VM_ALLOC_NORMAL); 4772 4773 /* 4774 * Since the pages were only sbusy while neither the 4775 * buffer nor the object lock was held by us, or 4776 * reallocated while vm_page_grab() slept for busy 4777 * relinguish, they could have been invalidated. 4778 * Recheck the valid bits and re-read as needed. 4779 * 4780 * Note that the last page is made fully valid in the 4781 * read loop, and partial validity for the page at 4782 * index count - 1 could mean that the page was 4783 * invalidated or removed, so we must restart for 4784 * safety as well. 4785 */ 4786 if (ma[i]->valid != VM_PAGE_BITS_ALL) 4787 redo = true; 4788 } 4789 if (redo && error == 0) 4790 goto again; 4791 VM_OBJECT_WUNLOCK(object); 4792 return (error != 0 ? VM_PAGER_ERROR : VM_PAGER_OK); 4793 } 4794 4795 #include "opt_ddb.h" 4796 #ifdef DDB 4797 #include <ddb/ddb.h> 4798 4799 /* DDB command to show buffer data */ 4800 DB_SHOW_COMMAND(buffer, db_show_buffer) 4801 { 4802 /* get args */ 4803 struct buf *bp = (struct buf *)addr; 4804 4805 if (!have_addr) { 4806 db_printf("usage: show buffer <addr>\n"); 4807 return; 4808 } 4809 4810 db_printf("buf at %p\n", bp); 4811 db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n", 4812 (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags, 4813 PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS); 4814 db_printf( 4815 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 4816 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, " 4817 "b_dep = %p\n", 4818 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 4819 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 4820 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first); 4821 db_printf("b_kvabase = %p, b_kvasize = %d\n", 4822 bp->b_kvabase, bp->b_kvasize); 4823 if (bp->b_npages) { 4824 int i; 4825 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 4826 for (i = 0; i < bp->b_npages; i++) { 4827 vm_page_t m; 4828 m = bp->b_pages[i]; 4829 if (m != NULL) 4830 db_printf("(%p, 0x%lx, 0x%lx)", m->object, 4831 (u_long)m->pindex, 4832 (u_long)VM_PAGE_TO_PHYS(m)); 4833 else 4834 db_printf("( ??? )"); 4835 if ((i + 1) < bp->b_npages) 4836 db_printf(","); 4837 } 4838 db_printf("\n"); 4839 } 4840 db_printf(" "); 4841 BUF_LOCKPRINTINFO(bp); 4842 } 4843 4844 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 4845 { 4846 struct buf *bp; 4847 int i; 4848 4849 for (i = 0; i < nbuf; i++) { 4850 bp = &buf[i]; 4851 if (BUF_ISLOCKED(bp)) { 4852 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4853 db_printf("\n"); 4854 } 4855 } 4856 } 4857 4858 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 4859 { 4860 struct vnode *vp; 4861 struct buf *bp; 4862 4863 if (!have_addr) { 4864 db_printf("usage: show vnodebufs <addr>\n"); 4865 return; 4866 } 4867 vp = (struct vnode *)addr; 4868 db_printf("Clean buffers:\n"); 4869 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 4870 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4871 db_printf("\n"); 4872 } 4873 db_printf("Dirty buffers:\n"); 4874 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 4875 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4876 db_printf("\n"); 4877 } 4878 } 4879 4880 DB_COMMAND(countfreebufs, db_coundfreebufs) 4881 { 4882 struct buf *bp; 4883 int i, used = 0, nfree = 0; 4884 4885 if (have_addr) { 4886 db_printf("usage: countfreebufs\n"); 4887 return; 4888 } 4889 4890 for (i = 0; i < nbuf; i++) { 4891 bp = &buf[i]; 4892 if (bp->b_qindex == QUEUE_EMPTY) 4893 nfree++; 4894 else 4895 used++; 4896 } 4897 4898 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 4899 nfree + used); 4900 db_printf("numfreebuffers is %d\n", numfreebuffers); 4901 } 4902 #endif /* DDB */ 4903