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 buf_track(bp, __func__); 1956 bstrategy(bp); 1957 1958 if ((oldflags & B_ASYNC) == 0) { 1959 int rtval = bufwait(bp); 1960 brelse(bp); 1961 return (rtval); 1962 } else if (space > hirunningspace) { 1963 /* 1964 * don't allow the async write to saturate the I/O 1965 * system. We will not deadlock here because 1966 * we are blocking waiting for I/O that is already in-progress 1967 * to complete. We do not block here if it is the update 1968 * or syncer daemon trying to clean up as that can lead 1969 * to deadlock. 1970 */ 1971 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 1972 waitrunningbufspace(); 1973 } 1974 1975 return (0); 1976 } 1977 1978 void 1979 bufbdflush(struct bufobj *bo, struct buf *bp) 1980 { 1981 struct buf *nbp; 1982 1983 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 1984 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 1985 altbufferflushes++; 1986 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 1987 BO_LOCK(bo); 1988 /* 1989 * Try to find a buffer to flush. 1990 */ 1991 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 1992 if ((nbp->b_vflags & BV_BKGRDINPROG) || 1993 BUF_LOCK(nbp, 1994 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 1995 continue; 1996 if (bp == nbp) 1997 panic("bdwrite: found ourselves"); 1998 BO_UNLOCK(bo); 1999 /* Don't countdeps with the bo lock held. */ 2000 if (buf_countdeps(nbp, 0)) { 2001 BO_LOCK(bo); 2002 BUF_UNLOCK(nbp); 2003 continue; 2004 } 2005 if (nbp->b_flags & B_CLUSTEROK) { 2006 vfs_bio_awrite(nbp); 2007 } else { 2008 bremfree(nbp); 2009 bawrite(nbp); 2010 } 2011 dirtybufferflushes++; 2012 break; 2013 } 2014 if (nbp == NULL) 2015 BO_UNLOCK(bo); 2016 } 2017 } 2018 2019 /* 2020 * Delayed write. (Buffer is marked dirty). Do not bother writing 2021 * anything if the buffer is marked invalid. 2022 * 2023 * Note that since the buffer must be completely valid, we can safely 2024 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 2025 * biodone() in order to prevent getblk from writing the buffer 2026 * out synchronously. 2027 */ 2028 void 2029 bdwrite(struct buf *bp) 2030 { 2031 struct thread *td = curthread; 2032 struct vnode *vp; 2033 struct bufobj *bo; 2034 2035 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2036 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2037 KASSERT((bp->b_flags & B_BARRIER) == 0, 2038 ("Barrier request in delayed write %p", bp)); 2039 BUF_ASSERT_HELD(bp); 2040 2041 if (bp->b_flags & B_INVAL) { 2042 brelse(bp); 2043 return; 2044 } 2045 2046 /* 2047 * If we have too many dirty buffers, don't create any more. 2048 * If we are wildly over our limit, then force a complete 2049 * cleanup. Otherwise, just keep the situation from getting 2050 * out of control. Note that we have to avoid a recursive 2051 * disaster and not try to clean up after our own cleanup! 2052 */ 2053 vp = bp->b_vp; 2054 bo = bp->b_bufobj; 2055 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 2056 td->td_pflags |= TDP_INBDFLUSH; 2057 BO_BDFLUSH(bo, bp); 2058 td->td_pflags &= ~TDP_INBDFLUSH; 2059 } else 2060 recursiveflushes++; 2061 2062 bdirty(bp); 2063 /* 2064 * Set B_CACHE, indicating that the buffer is fully valid. This is 2065 * true even of NFS now. 2066 */ 2067 bp->b_flags |= B_CACHE; 2068 2069 /* 2070 * This bmap keeps the system from needing to do the bmap later, 2071 * perhaps when the system is attempting to do a sync. Since it 2072 * is likely that the indirect block -- or whatever other datastructure 2073 * that the filesystem needs is still in memory now, it is a good 2074 * thing to do this. Note also, that if the pageout daemon is 2075 * requesting a sync -- there might not be enough memory to do 2076 * the bmap then... So, this is important to do. 2077 */ 2078 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 2079 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 2080 } 2081 2082 buf_track(bp, __func__); 2083 2084 /* 2085 * Set the *dirty* buffer range based upon the VM system dirty 2086 * pages. 2087 * 2088 * Mark the buffer pages as clean. We need to do this here to 2089 * satisfy the vnode_pager and the pageout daemon, so that it 2090 * thinks that the pages have been "cleaned". Note that since 2091 * the pages are in a delayed write buffer -- the VFS layer 2092 * "will" see that the pages get written out on the next sync, 2093 * or perhaps the cluster will be completed. 2094 */ 2095 vfs_clean_pages_dirty_buf(bp); 2096 bqrelse(bp); 2097 2098 /* 2099 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 2100 * due to the softdep code. 2101 */ 2102 } 2103 2104 /* 2105 * bdirty: 2106 * 2107 * Turn buffer into delayed write request. We must clear BIO_READ and 2108 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 2109 * itself to properly update it in the dirty/clean lists. We mark it 2110 * B_DONE to ensure that any asynchronization of the buffer properly 2111 * clears B_DONE ( else a panic will occur later ). 2112 * 2113 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 2114 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 2115 * should only be called if the buffer is known-good. 2116 * 2117 * Since the buffer is not on a queue, we do not update the numfreebuffers 2118 * count. 2119 * 2120 * The buffer must be on QUEUE_NONE. 2121 */ 2122 void 2123 bdirty(struct buf *bp) 2124 { 2125 2126 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 2127 bp, bp->b_vp, bp->b_flags); 2128 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2129 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 2130 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 2131 BUF_ASSERT_HELD(bp); 2132 bp->b_flags &= ~(B_RELBUF); 2133 bp->b_iocmd = BIO_WRITE; 2134 2135 if ((bp->b_flags & B_DELWRI) == 0) { 2136 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 2137 reassignbuf(bp); 2138 bdirtyadd(); 2139 } 2140 } 2141 2142 /* 2143 * bundirty: 2144 * 2145 * Clear B_DELWRI for buffer. 2146 * 2147 * Since the buffer is not on a queue, we do not update the numfreebuffers 2148 * count. 2149 * 2150 * The buffer must be on QUEUE_NONE. 2151 */ 2152 2153 void 2154 bundirty(struct buf *bp) 2155 { 2156 2157 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2158 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2159 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 2160 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 2161 BUF_ASSERT_HELD(bp); 2162 2163 if (bp->b_flags & B_DELWRI) { 2164 bp->b_flags &= ~B_DELWRI; 2165 reassignbuf(bp); 2166 bdirtysub(); 2167 } 2168 /* 2169 * Since it is now being written, we can clear its deferred write flag. 2170 */ 2171 bp->b_flags &= ~B_DEFERRED; 2172 } 2173 2174 /* 2175 * bawrite: 2176 * 2177 * Asynchronous write. Start output on a buffer, but do not wait for 2178 * it to complete. The buffer is released when the output completes. 2179 * 2180 * bwrite() ( or the VOP routine anyway ) is responsible for handling 2181 * B_INVAL buffers. Not us. 2182 */ 2183 void 2184 bawrite(struct buf *bp) 2185 { 2186 2187 bp->b_flags |= B_ASYNC; 2188 (void) bwrite(bp); 2189 } 2190 2191 /* 2192 * babarrierwrite: 2193 * 2194 * Asynchronous barrier write. Start output on a buffer, but do not 2195 * wait for it to complete. Place a write barrier after this write so 2196 * that this buffer and all buffers written before it are committed to 2197 * the disk before any buffers written after this write are committed 2198 * to the disk. The buffer is released when the output completes. 2199 */ 2200 void 2201 babarrierwrite(struct buf *bp) 2202 { 2203 2204 bp->b_flags |= B_ASYNC | B_BARRIER; 2205 (void) bwrite(bp); 2206 } 2207 2208 /* 2209 * bbarrierwrite: 2210 * 2211 * Synchronous barrier write. Start output on a buffer and wait for 2212 * it to complete. Place a write barrier after this write so that 2213 * this buffer and all buffers written before it are committed to 2214 * the disk before any buffers written after this write are committed 2215 * to the disk. The buffer is released when the output completes. 2216 */ 2217 int 2218 bbarrierwrite(struct buf *bp) 2219 { 2220 2221 bp->b_flags |= B_BARRIER; 2222 return (bwrite(bp)); 2223 } 2224 2225 /* 2226 * bwillwrite: 2227 * 2228 * Called prior to the locking of any vnodes when we are expecting to 2229 * write. We do not want to starve the buffer cache with too many 2230 * dirty buffers so we block here. By blocking prior to the locking 2231 * of any vnodes we attempt to avoid the situation where a locked vnode 2232 * prevents the various system daemons from flushing related buffers. 2233 */ 2234 void 2235 bwillwrite(void) 2236 { 2237 2238 if (numdirtybuffers >= hidirtybuffers) { 2239 mtx_lock(&bdirtylock); 2240 while (numdirtybuffers >= hidirtybuffers) { 2241 bdirtywait = 1; 2242 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4), 2243 "flswai", 0); 2244 } 2245 mtx_unlock(&bdirtylock); 2246 } 2247 } 2248 2249 /* 2250 * Return true if we have too many dirty buffers. 2251 */ 2252 int 2253 buf_dirty_count_severe(void) 2254 { 2255 2256 return(numdirtybuffers >= hidirtybuffers); 2257 } 2258 2259 /* 2260 * brelse: 2261 * 2262 * Release a busy buffer and, if requested, free its resources. The 2263 * buffer will be stashed in the appropriate bufqueue[] allowing it 2264 * to be accessed later as a cache entity or reused for other purposes. 2265 */ 2266 void 2267 brelse(struct buf *bp) 2268 { 2269 int qindex; 2270 2271 /* 2272 * Many functions erroneously call brelse with a NULL bp under rare 2273 * error conditions. Simply return when called with a NULL bp. 2274 */ 2275 if (bp == NULL) 2276 return; 2277 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 2278 bp, bp->b_vp, bp->b_flags); 2279 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 2280 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 2281 KASSERT((bp->b_flags & B_VMIO) != 0 || (bp->b_flags & B_NOREUSE) == 0, 2282 ("brelse: non-VMIO buffer marked NOREUSE")); 2283 2284 if (BUF_LOCKRECURSED(bp)) { 2285 /* 2286 * Do not process, in particular, do not handle the 2287 * B_INVAL/B_RELBUF and do not release to free list. 2288 */ 2289 BUF_UNLOCK(bp); 2290 return; 2291 } 2292 2293 if (bp->b_flags & B_MANAGED) { 2294 bqrelse(bp); 2295 return; 2296 } 2297 2298 if ((bp->b_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) { 2299 BO_LOCK(bp->b_bufobj); 2300 bp->b_vflags &= ~BV_BKGRDERR; 2301 BO_UNLOCK(bp->b_bufobj); 2302 bdirty(bp); 2303 } 2304 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 2305 !(bp->b_flags & B_INVAL)) { 2306 /* 2307 * Failed write, redirty. Must clear BIO_ERROR to prevent 2308 * pages from being scrapped. 2309 */ 2310 bp->b_ioflags &= ~BIO_ERROR; 2311 bdirty(bp); 2312 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 2313 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 2314 /* 2315 * Either a failed read I/O or we were asked to free or not 2316 * cache the buffer. 2317 */ 2318 bp->b_flags |= B_INVAL; 2319 if (!LIST_EMPTY(&bp->b_dep)) 2320 buf_deallocate(bp); 2321 if (bp->b_flags & B_DELWRI) 2322 bdirtysub(); 2323 bp->b_flags &= ~(B_DELWRI | B_CACHE); 2324 if ((bp->b_flags & B_VMIO) == 0) { 2325 allocbuf(bp, 0); 2326 if (bp->b_vp) 2327 brelvp(bp); 2328 } 2329 } 2330 2331 /* 2332 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_truncate() 2333 * is called with B_DELWRI set, the underlying pages may wind up 2334 * getting freed causing a previous write (bdwrite()) to get 'lost' 2335 * because pages associated with a B_DELWRI bp are marked clean. 2336 * 2337 * We still allow the B_INVAL case to call vfs_vmio_truncate(), even 2338 * if B_DELWRI is set. 2339 */ 2340 if (bp->b_flags & B_DELWRI) 2341 bp->b_flags &= ~B_RELBUF; 2342 2343 /* 2344 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 2345 * constituted, not even NFS buffers now. Two flags effect this. If 2346 * B_INVAL, the struct buf is invalidated but the VM object is kept 2347 * around ( i.e. so it is trivial to reconstitute the buffer later ). 2348 * 2349 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 2350 * invalidated. BIO_ERROR cannot be set for a failed write unless the 2351 * buffer is also B_INVAL because it hits the re-dirtying code above. 2352 * 2353 * Normally we can do this whether a buffer is B_DELWRI or not. If 2354 * the buffer is an NFS buffer, it is tracking piecemeal writes or 2355 * the commit state and we cannot afford to lose the buffer. If the 2356 * buffer has a background write in progress, we need to keep it 2357 * around to prevent it from being reconstituted and starting a second 2358 * background write. 2359 */ 2360 if ((bp->b_flags & B_VMIO) && (bp->b_flags & B_NOCACHE || 2361 (bp->b_ioflags & BIO_ERROR && bp->b_iocmd == BIO_READ)) && 2362 !(bp->b_vp->v_mount != NULL && 2363 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 2364 !vn_isdisk(bp->b_vp, NULL) && (bp->b_flags & B_DELWRI))) { 2365 vfs_vmio_invalidate(bp); 2366 allocbuf(bp, 0); 2367 } 2368 2369 if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0 || 2370 (bp->b_flags & (B_DELWRI | B_NOREUSE)) == B_NOREUSE) { 2371 allocbuf(bp, 0); 2372 bp->b_flags &= ~B_NOREUSE; 2373 if (bp->b_vp != NULL) 2374 brelvp(bp); 2375 } 2376 2377 /* 2378 * If the buffer has junk contents signal it and eventually 2379 * clean up B_DELWRI and diassociate the vnode so that gbincore() 2380 * doesn't find it. 2381 */ 2382 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 2383 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 2384 bp->b_flags |= B_INVAL; 2385 if (bp->b_flags & B_INVAL) { 2386 if (bp->b_flags & B_DELWRI) 2387 bundirty(bp); 2388 if (bp->b_vp) 2389 brelvp(bp); 2390 } 2391 2392 buf_track(bp, __func__); 2393 2394 /* buffers with no memory */ 2395 if (bp->b_bufsize == 0) { 2396 buf_free(bp); 2397 return; 2398 } 2399 /* buffers with junk contents */ 2400 if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 2401 (bp->b_ioflags & BIO_ERROR)) { 2402 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 2403 if (bp->b_vflags & BV_BKGRDINPROG) 2404 panic("losing buffer 2"); 2405 qindex = QUEUE_CLEAN; 2406 bp->b_flags |= B_AGE; 2407 /* remaining buffers */ 2408 } else if (bp->b_flags & B_DELWRI) 2409 qindex = QUEUE_DIRTY; 2410 else 2411 qindex = QUEUE_CLEAN; 2412 2413 binsfree(bp, qindex); 2414 2415 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 2416 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 2417 panic("brelse: not dirty"); 2418 /* unlock */ 2419 BUF_UNLOCK(bp); 2420 if (qindex == QUEUE_CLEAN) 2421 bufspace_wakeup(); 2422 } 2423 2424 /* 2425 * Release a buffer back to the appropriate queue but do not try to free 2426 * it. The buffer is expected to be used again soon. 2427 * 2428 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 2429 * biodone() to requeue an async I/O on completion. It is also used when 2430 * known good buffers need to be requeued but we think we may need the data 2431 * again soon. 2432 * 2433 * XXX we should be able to leave the B_RELBUF hint set on completion. 2434 */ 2435 void 2436 bqrelse(struct buf *bp) 2437 { 2438 int qindex; 2439 2440 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2441 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 2442 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 2443 2444 qindex = QUEUE_NONE; 2445 if (BUF_LOCKRECURSED(bp)) { 2446 /* do not release to free list */ 2447 BUF_UNLOCK(bp); 2448 return; 2449 } 2450 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 2451 2452 if (bp->b_flags & B_MANAGED) { 2453 if (bp->b_flags & B_REMFREE) 2454 bremfreef(bp); 2455 goto out; 2456 } 2457 2458 /* buffers with stale but valid contents */ 2459 if ((bp->b_flags & B_DELWRI) != 0 || (bp->b_vflags & (BV_BKGRDINPROG | 2460 BV_BKGRDERR)) == BV_BKGRDERR) { 2461 BO_LOCK(bp->b_bufobj); 2462 bp->b_vflags &= ~BV_BKGRDERR; 2463 BO_UNLOCK(bp->b_bufobj); 2464 qindex = QUEUE_DIRTY; 2465 } else { 2466 if ((bp->b_flags & B_DELWRI) == 0 && 2467 (bp->b_xflags & BX_VNDIRTY)) 2468 panic("bqrelse: not dirty"); 2469 if ((bp->b_flags & B_NOREUSE) != 0) { 2470 brelse(bp); 2471 return; 2472 } 2473 qindex = QUEUE_CLEAN; 2474 } 2475 binsfree(bp, qindex); 2476 2477 out: 2478 buf_track(bp, __func__); 2479 /* unlock */ 2480 BUF_UNLOCK(bp); 2481 if (qindex == QUEUE_CLEAN) 2482 bufspace_wakeup(); 2483 } 2484 2485 /* 2486 * Complete I/O to a VMIO backed page. Validate the pages as appropriate, 2487 * restore bogus pages. 2488 */ 2489 static void 2490 vfs_vmio_iodone(struct buf *bp) 2491 { 2492 vm_ooffset_t foff; 2493 vm_page_t m; 2494 vm_object_t obj; 2495 struct vnode *vp; 2496 int bogus, i, iosize; 2497 2498 obj = bp->b_bufobj->bo_object; 2499 KASSERT(obj->paging_in_progress >= bp->b_npages, 2500 ("vfs_vmio_iodone: paging in progress(%d) < b_npages(%d)", 2501 obj->paging_in_progress, bp->b_npages)); 2502 2503 vp = bp->b_vp; 2504 KASSERT(vp->v_holdcnt > 0, 2505 ("vfs_vmio_iodone: vnode %p has zero hold count", vp)); 2506 KASSERT(vp->v_object != NULL, 2507 ("vfs_vmio_iodone: vnode %p has no vm_object", vp)); 2508 2509 foff = bp->b_offset; 2510 KASSERT(bp->b_offset != NOOFFSET, 2511 ("vfs_vmio_iodone: bp %p has no buffer offset", bp)); 2512 2513 bogus = 0; 2514 iosize = bp->b_bcount - bp->b_resid; 2515 VM_OBJECT_WLOCK(obj); 2516 for (i = 0; i < bp->b_npages; i++) { 2517 int resid; 2518 2519 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 2520 if (resid > iosize) 2521 resid = iosize; 2522 2523 /* 2524 * cleanup bogus pages, restoring the originals 2525 */ 2526 m = bp->b_pages[i]; 2527 if (m == bogus_page) { 2528 bogus = 1; 2529 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 2530 if (m == NULL) 2531 panic("biodone: page disappeared!"); 2532 bp->b_pages[i] = m; 2533 } else if ((bp->b_iocmd == BIO_READ) && resid > 0) { 2534 /* 2535 * In the write case, the valid and clean bits are 2536 * already changed correctly ( see bdwrite() ), so we 2537 * only need to do this here in the read case. 2538 */ 2539 KASSERT((m->dirty & vm_page_bits(foff & PAGE_MASK, 2540 resid)) == 0, ("vfs_vmio_iodone: page %p " 2541 "has unexpected dirty bits", m)); 2542 vfs_page_set_valid(bp, foff, m); 2543 } 2544 KASSERT(OFF_TO_IDX(foff) == m->pindex, 2545 ("vfs_vmio_iodone: foff(%jd)/pindex(%ju) mismatch", 2546 (intmax_t)foff, (uintmax_t)m->pindex)); 2547 2548 vm_page_sunbusy(m); 2549 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2550 iosize -= resid; 2551 } 2552 vm_object_pip_wakeupn(obj, bp->b_npages); 2553 VM_OBJECT_WUNLOCK(obj); 2554 if (bogus && buf_mapped(bp)) { 2555 BUF_CHECK_MAPPED(bp); 2556 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 2557 bp->b_pages, bp->b_npages); 2558 } 2559 } 2560 2561 /* 2562 * Unwire a page held by a buf and place it on the appropriate vm queue. 2563 */ 2564 static void 2565 vfs_vmio_unwire(struct buf *bp, vm_page_t m) 2566 { 2567 bool freed; 2568 2569 vm_page_lock(m); 2570 if (vm_page_unwire(m, PQ_NONE)) { 2571 /* 2572 * Determine if the page should be freed before adding 2573 * it to the inactive queue. 2574 */ 2575 if (m->valid == 0) { 2576 freed = !vm_page_busied(m); 2577 if (freed) 2578 vm_page_free(m); 2579 } else if ((bp->b_flags & B_DIRECT) != 0) 2580 freed = vm_page_try_to_free(m); 2581 else 2582 freed = false; 2583 if (!freed) { 2584 /* 2585 * If the page is unlikely to be reused, let the 2586 * VM know. Otherwise, maintain LRU page 2587 * ordering and put the page at the tail of the 2588 * inactive queue. 2589 */ 2590 if ((bp->b_flags & B_NOREUSE) != 0) 2591 vm_page_deactivate_noreuse(m); 2592 else 2593 vm_page_deactivate(m); 2594 } 2595 } 2596 vm_page_unlock(m); 2597 } 2598 2599 /* 2600 * Perform page invalidation when a buffer is released. The fully invalid 2601 * pages will be reclaimed later in vfs_vmio_truncate(). 2602 */ 2603 static void 2604 vfs_vmio_invalidate(struct buf *bp) 2605 { 2606 vm_object_t obj; 2607 vm_page_t m; 2608 int i, resid, poffset, presid; 2609 2610 if (buf_mapped(bp)) { 2611 BUF_CHECK_MAPPED(bp); 2612 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages); 2613 } else 2614 BUF_CHECK_UNMAPPED(bp); 2615 /* 2616 * Get the base offset and length of the buffer. Note that 2617 * in the VMIO case if the buffer block size is not 2618 * page-aligned then b_data pointer may not be page-aligned. 2619 * But our b_pages[] array *IS* page aligned. 2620 * 2621 * block sizes less then DEV_BSIZE (usually 512) are not 2622 * supported due to the page granularity bits (m->valid, 2623 * m->dirty, etc...). 2624 * 2625 * See man buf(9) for more information 2626 */ 2627 obj = bp->b_bufobj->bo_object; 2628 resid = bp->b_bufsize; 2629 poffset = bp->b_offset & PAGE_MASK; 2630 VM_OBJECT_WLOCK(obj); 2631 for (i = 0; i < bp->b_npages; i++) { 2632 m = bp->b_pages[i]; 2633 if (m == bogus_page) 2634 panic("vfs_vmio_invalidate: Unexpected bogus page."); 2635 bp->b_pages[i] = NULL; 2636 2637 presid = resid > (PAGE_SIZE - poffset) ? 2638 (PAGE_SIZE - poffset) : resid; 2639 KASSERT(presid >= 0, ("brelse: extra page")); 2640 while (vm_page_xbusied(m)) { 2641 vm_page_lock(m); 2642 VM_OBJECT_WUNLOCK(obj); 2643 vm_page_busy_sleep(m, "mbncsh", true); 2644 VM_OBJECT_WLOCK(obj); 2645 } 2646 if (pmap_page_wired_mappings(m) == 0) 2647 vm_page_set_invalid(m, poffset, presid); 2648 vfs_vmio_unwire(bp, m); 2649 resid -= presid; 2650 poffset = 0; 2651 } 2652 VM_OBJECT_WUNLOCK(obj); 2653 bp->b_npages = 0; 2654 } 2655 2656 /* 2657 * Page-granular truncation of an existing VMIO buffer. 2658 */ 2659 static void 2660 vfs_vmio_truncate(struct buf *bp, int desiredpages) 2661 { 2662 vm_object_t obj; 2663 vm_page_t m; 2664 int i; 2665 2666 if (bp->b_npages == desiredpages) 2667 return; 2668 2669 if (buf_mapped(bp)) { 2670 BUF_CHECK_MAPPED(bp); 2671 pmap_qremove((vm_offset_t)trunc_page((vm_offset_t)bp->b_data) + 2672 (desiredpages << PAGE_SHIFT), bp->b_npages - desiredpages); 2673 } else 2674 BUF_CHECK_UNMAPPED(bp); 2675 obj = bp->b_bufobj->bo_object; 2676 if (obj != NULL) 2677 VM_OBJECT_WLOCK(obj); 2678 for (i = desiredpages; i < bp->b_npages; i++) { 2679 m = bp->b_pages[i]; 2680 KASSERT(m != bogus_page, ("allocbuf: bogus page found")); 2681 bp->b_pages[i] = NULL; 2682 vfs_vmio_unwire(bp, m); 2683 } 2684 if (obj != NULL) 2685 VM_OBJECT_WUNLOCK(obj); 2686 bp->b_npages = desiredpages; 2687 } 2688 2689 /* 2690 * Byte granular extension of VMIO buffers. 2691 */ 2692 static void 2693 vfs_vmio_extend(struct buf *bp, int desiredpages, int size) 2694 { 2695 /* 2696 * We are growing the buffer, possibly in a 2697 * byte-granular fashion. 2698 */ 2699 vm_object_t obj; 2700 vm_offset_t toff; 2701 vm_offset_t tinc; 2702 vm_page_t m; 2703 2704 /* 2705 * Step 1, bring in the VM pages from the object, allocating 2706 * them if necessary. We must clear B_CACHE if these pages 2707 * are not valid for the range covered by the buffer. 2708 */ 2709 obj = bp->b_bufobj->bo_object; 2710 VM_OBJECT_WLOCK(obj); 2711 while (bp->b_npages < desiredpages) { 2712 /* 2713 * We must allocate system pages since blocking 2714 * here could interfere with paging I/O, no 2715 * matter which process we are. 2716 * 2717 * Only exclusive busy can be tested here. 2718 * Blocking on shared busy might lead to 2719 * deadlocks once allocbuf() is called after 2720 * pages are vfs_busy_pages(). 2721 */ 2722 m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) + bp->b_npages, 2723 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM | 2724 VM_ALLOC_WIRED | VM_ALLOC_IGN_SBUSY | 2725 VM_ALLOC_COUNT(desiredpages - bp->b_npages)); 2726 if (m->valid == 0) 2727 bp->b_flags &= ~B_CACHE; 2728 bp->b_pages[bp->b_npages] = m; 2729 ++bp->b_npages; 2730 } 2731 2732 /* 2733 * Step 2. We've loaded the pages into the buffer, 2734 * we have to figure out if we can still have B_CACHE 2735 * set. Note that B_CACHE is set according to the 2736 * byte-granular range ( bcount and size ), not the 2737 * aligned range ( newbsize ). 2738 * 2739 * The VM test is against m->valid, which is DEV_BSIZE 2740 * aligned. Needless to say, the validity of the data 2741 * needs to also be DEV_BSIZE aligned. Note that this 2742 * fails with NFS if the server or some other client 2743 * extends the file's EOF. If our buffer is resized, 2744 * B_CACHE may remain set! XXX 2745 */ 2746 toff = bp->b_bcount; 2747 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 2748 while ((bp->b_flags & B_CACHE) && toff < size) { 2749 vm_pindex_t pi; 2750 2751 if (tinc > (size - toff)) 2752 tinc = size - toff; 2753 pi = ((bp->b_offset & PAGE_MASK) + toff) >> PAGE_SHIFT; 2754 m = bp->b_pages[pi]; 2755 vfs_buf_test_cache(bp, bp->b_offset, toff, tinc, m); 2756 toff += tinc; 2757 tinc = PAGE_SIZE; 2758 } 2759 VM_OBJECT_WUNLOCK(obj); 2760 2761 /* 2762 * Step 3, fixup the KVA pmap. 2763 */ 2764 if (buf_mapped(bp)) 2765 bpmap_qenter(bp); 2766 else 2767 BUF_CHECK_UNMAPPED(bp); 2768 } 2769 2770 /* 2771 * Check to see if a block at a particular lbn is available for a clustered 2772 * write. 2773 */ 2774 static int 2775 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 2776 { 2777 struct buf *bpa; 2778 int match; 2779 2780 match = 0; 2781 2782 /* If the buf isn't in core skip it */ 2783 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 2784 return (0); 2785 2786 /* If the buf is busy we don't want to wait for it */ 2787 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2788 return (0); 2789 2790 /* Only cluster with valid clusterable delayed write buffers */ 2791 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 2792 (B_DELWRI | B_CLUSTEROK)) 2793 goto done; 2794 2795 if (bpa->b_bufsize != size) 2796 goto done; 2797 2798 /* 2799 * Check to see if it is in the expected place on disk and that the 2800 * block has been mapped. 2801 */ 2802 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 2803 match = 1; 2804 done: 2805 BUF_UNLOCK(bpa); 2806 return (match); 2807 } 2808 2809 /* 2810 * vfs_bio_awrite: 2811 * 2812 * Implement clustered async writes for clearing out B_DELWRI buffers. 2813 * This is much better then the old way of writing only one buffer at 2814 * a time. Note that we may not be presented with the buffers in the 2815 * correct order, so we search for the cluster in both directions. 2816 */ 2817 int 2818 vfs_bio_awrite(struct buf *bp) 2819 { 2820 struct bufobj *bo; 2821 int i; 2822 int j; 2823 daddr_t lblkno = bp->b_lblkno; 2824 struct vnode *vp = bp->b_vp; 2825 int ncl; 2826 int nwritten; 2827 int size; 2828 int maxcl; 2829 int gbflags; 2830 2831 bo = &vp->v_bufobj; 2832 gbflags = (bp->b_data == unmapped_buf) ? GB_UNMAPPED : 0; 2833 /* 2834 * right now we support clustered writing only to regular files. If 2835 * we find a clusterable block we could be in the middle of a cluster 2836 * rather then at the beginning. 2837 */ 2838 if ((vp->v_type == VREG) && 2839 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 2840 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 2841 2842 size = vp->v_mount->mnt_stat.f_iosize; 2843 maxcl = MAXPHYS / size; 2844 2845 BO_RLOCK(bo); 2846 for (i = 1; i < maxcl; i++) 2847 if (vfs_bio_clcheck(vp, size, lblkno + i, 2848 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 2849 break; 2850 2851 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 2852 if (vfs_bio_clcheck(vp, size, lblkno - j, 2853 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 2854 break; 2855 BO_RUNLOCK(bo); 2856 --j; 2857 ncl = i + j; 2858 /* 2859 * this is a possible cluster write 2860 */ 2861 if (ncl != 1) { 2862 BUF_UNLOCK(bp); 2863 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl, 2864 gbflags); 2865 return (nwritten); 2866 } 2867 } 2868 bremfree(bp); 2869 bp->b_flags |= B_ASYNC; 2870 /* 2871 * default (old) behavior, writing out only one block 2872 * 2873 * XXX returns b_bufsize instead of b_bcount for nwritten? 2874 */ 2875 nwritten = bp->b_bufsize; 2876 (void) bwrite(bp); 2877 2878 return (nwritten); 2879 } 2880 2881 /* 2882 * getnewbuf_kva: 2883 * 2884 * Allocate KVA for an empty buf header according to gbflags. 2885 */ 2886 static int 2887 getnewbuf_kva(struct buf *bp, int gbflags, int maxsize) 2888 { 2889 2890 if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_UNMAPPED) { 2891 /* 2892 * In order to keep fragmentation sane we only allocate kva 2893 * in BKVASIZE chunks. XXX with vmem we can do page size. 2894 */ 2895 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2896 2897 if (maxsize != bp->b_kvasize && 2898 bufkva_alloc(bp, maxsize, gbflags)) 2899 return (ENOSPC); 2900 } 2901 return (0); 2902 } 2903 2904 /* 2905 * getnewbuf: 2906 * 2907 * Find and initialize a new buffer header, freeing up existing buffers 2908 * in the bufqueues as necessary. The new buffer is returned locked. 2909 * 2910 * We block if: 2911 * We have insufficient buffer headers 2912 * We have insufficient buffer space 2913 * buffer_arena is too fragmented ( space reservation fails ) 2914 * If we have to flush dirty buffers ( but we try to avoid this ) 2915 * 2916 * The caller is responsible for releasing the reserved bufspace after 2917 * allocbuf() is called. 2918 */ 2919 static struct buf * 2920 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int maxsize, int gbflags) 2921 { 2922 struct buf *bp; 2923 bool metadata, reserved; 2924 2925 bp = NULL; 2926 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 2927 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 2928 if (!unmapped_buf_allowed) 2929 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC); 2930 2931 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 || 2932 vp->v_type == VCHR) 2933 metadata = true; 2934 else 2935 metadata = false; 2936 atomic_add_int(&getnewbufcalls, 1); 2937 reserved = false; 2938 do { 2939 if (reserved == false && 2940 bufspace_reserve(maxsize, metadata) != 0) 2941 continue; 2942 reserved = true; 2943 if ((bp = buf_alloc()) == NULL) 2944 continue; 2945 if (getnewbuf_kva(bp, gbflags, maxsize) == 0) 2946 return (bp); 2947 break; 2948 } while(buf_scan(false) == 0); 2949 2950 if (reserved) 2951 atomic_subtract_long(&bufspace, maxsize); 2952 if (bp != NULL) { 2953 bp->b_flags |= B_INVAL; 2954 brelse(bp); 2955 } 2956 bufspace_wait(vp, gbflags, slpflag, slptimeo); 2957 2958 return (NULL); 2959 } 2960 2961 /* 2962 * buf_daemon: 2963 * 2964 * buffer flushing daemon. Buffers are normally flushed by the 2965 * update daemon but if it cannot keep up this process starts to 2966 * take the load in an attempt to prevent getnewbuf() from blocking. 2967 */ 2968 static struct kproc_desc buf_kp = { 2969 "bufdaemon", 2970 buf_daemon, 2971 &bufdaemonproc 2972 }; 2973 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 2974 2975 static int 2976 buf_flush(struct vnode *vp, int target) 2977 { 2978 int flushed; 2979 2980 flushed = flushbufqueues(vp, target, 0); 2981 if (flushed == 0) { 2982 /* 2983 * Could not find any buffers without rollback 2984 * dependencies, so just write the first one 2985 * in the hopes of eventually making progress. 2986 */ 2987 if (vp != NULL && target > 2) 2988 target /= 2; 2989 flushbufqueues(vp, target, 1); 2990 } 2991 return (flushed); 2992 } 2993 2994 static void 2995 buf_daemon() 2996 { 2997 int lodirty; 2998 2999 /* 3000 * This process needs to be suspended prior to shutdown sync. 3001 */ 3002 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 3003 SHUTDOWN_PRI_LAST); 3004 3005 /* 3006 * This process is allowed to take the buffer cache to the limit 3007 */ 3008 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 3009 mtx_lock(&bdlock); 3010 for (;;) { 3011 bd_request = 0; 3012 mtx_unlock(&bdlock); 3013 3014 kproc_suspend_check(bufdaemonproc); 3015 lodirty = lodirtybuffers; 3016 if (bd_speedupreq) { 3017 lodirty = numdirtybuffers / 2; 3018 bd_speedupreq = 0; 3019 } 3020 /* 3021 * Do the flush. Limit the amount of in-transit I/O we 3022 * allow to build up, otherwise we would completely saturate 3023 * the I/O system. 3024 */ 3025 while (numdirtybuffers > lodirty) { 3026 if (buf_flush(NULL, numdirtybuffers - lodirty) == 0) 3027 break; 3028 kern_yield(PRI_USER); 3029 } 3030 3031 /* 3032 * Only clear bd_request if we have reached our low water 3033 * mark. The buf_daemon normally waits 1 second and 3034 * then incrementally flushes any dirty buffers that have 3035 * built up, within reason. 3036 * 3037 * If we were unable to hit our low water mark and couldn't 3038 * find any flushable buffers, we sleep for a short period 3039 * to avoid endless loops on unlockable buffers. 3040 */ 3041 mtx_lock(&bdlock); 3042 if (numdirtybuffers <= lodirtybuffers) { 3043 /* 3044 * We reached our low water mark, reset the 3045 * request and sleep until we are needed again. 3046 * The sleep is just so the suspend code works. 3047 */ 3048 bd_request = 0; 3049 /* 3050 * Do an extra wakeup in case dirty threshold 3051 * changed via sysctl and the explicit transition 3052 * out of shortfall was missed. 3053 */ 3054 bdirtywakeup(); 3055 if (runningbufspace <= lorunningspace) 3056 runningwakeup(); 3057 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 3058 } else { 3059 /* 3060 * We couldn't find any flushable dirty buffers but 3061 * still have too many dirty buffers, we 3062 * have to sleep and try again. (rare) 3063 */ 3064 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 3065 } 3066 } 3067 } 3068 3069 /* 3070 * flushbufqueues: 3071 * 3072 * Try to flush a buffer in the dirty queue. We must be careful to 3073 * free up B_INVAL buffers instead of write them, which NFS is 3074 * particularly sensitive to. 3075 */ 3076 static int flushwithdeps = 0; 3077 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 3078 0, "Number of buffers flushed with dependecies that require rollbacks"); 3079 3080 static int 3081 flushbufqueues(struct vnode *lvp, int target, int flushdeps) 3082 { 3083 struct buf *sentinel; 3084 struct vnode *vp; 3085 struct mount *mp; 3086 struct buf *bp; 3087 int hasdeps; 3088 int flushed; 3089 int queue; 3090 int error; 3091 bool unlock; 3092 3093 flushed = 0; 3094 queue = QUEUE_DIRTY; 3095 bp = NULL; 3096 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 3097 sentinel->b_qindex = QUEUE_SENTINEL; 3098 mtx_lock(&bqlocks[queue]); 3099 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist); 3100 mtx_unlock(&bqlocks[queue]); 3101 while (flushed != target) { 3102 maybe_yield(); 3103 mtx_lock(&bqlocks[queue]); 3104 bp = TAILQ_NEXT(sentinel, b_freelist); 3105 if (bp != NULL) { 3106 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 3107 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel, 3108 b_freelist); 3109 } else { 3110 mtx_unlock(&bqlocks[queue]); 3111 break; 3112 } 3113 /* 3114 * Skip sentinels inserted by other invocations of the 3115 * flushbufqueues(), taking care to not reorder them. 3116 * 3117 * Only flush the buffers that belong to the 3118 * vnode locked by the curthread. 3119 */ 3120 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL && 3121 bp->b_vp != lvp)) { 3122 mtx_unlock(&bqlocks[queue]); 3123 continue; 3124 } 3125 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL); 3126 mtx_unlock(&bqlocks[queue]); 3127 if (error != 0) 3128 continue; 3129 3130 /* 3131 * BKGRDINPROG can only be set with the buf and bufobj 3132 * locks both held. We tolerate a race to clear it here. 3133 */ 3134 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 3135 (bp->b_flags & B_DELWRI) == 0) { 3136 BUF_UNLOCK(bp); 3137 continue; 3138 } 3139 if (bp->b_flags & B_INVAL) { 3140 bremfreef(bp); 3141 brelse(bp); 3142 flushed++; 3143 continue; 3144 } 3145 3146 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 3147 if (flushdeps == 0) { 3148 BUF_UNLOCK(bp); 3149 continue; 3150 } 3151 hasdeps = 1; 3152 } else 3153 hasdeps = 0; 3154 /* 3155 * We must hold the lock on a vnode before writing 3156 * one of its buffers. Otherwise we may confuse, or 3157 * in the case of a snapshot vnode, deadlock the 3158 * system. 3159 * 3160 * The lock order here is the reverse of the normal 3161 * of vnode followed by buf lock. This is ok because 3162 * the NOWAIT will prevent deadlock. 3163 */ 3164 vp = bp->b_vp; 3165 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 3166 BUF_UNLOCK(bp); 3167 continue; 3168 } 3169 if (lvp == NULL) { 3170 unlock = true; 3171 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT); 3172 } else { 3173 ASSERT_VOP_LOCKED(vp, "getbuf"); 3174 unlock = false; 3175 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 : 3176 vn_lock(vp, LK_TRYUPGRADE); 3177 } 3178 if (error == 0) { 3179 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 3180 bp, bp->b_vp, bp->b_flags); 3181 if (curproc == bufdaemonproc) { 3182 vfs_bio_awrite(bp); 3183 } else { 3184 bremfree(bp); 3185 bwrite(bp); 3186 notbufdflushes++; 3187 } 3188 vn_finished_write(mp); 3189 if (unlock) 3190 VOP_UNLOCK(vp, 0); 3191 flushwithdeps += hasdeps; 3192 flushed++; 3193 3194 /* 3195 * Sleeping on runningbufspace while holding 3196 * vnode lock leads to deadlock. 3197 */ 3198 if (curproc == bufdaemonproc && 3199 runningbufspace > hirunningspace) 3200 waitrunningbufspace(); 3201 continue; 3202 } 3203 vn_finished_write(mp); 3204 BUF_UNLOCK(bp); 3205 } 3206 mtx_lock(&bqlocks[queue]); 3207 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 3208 mtx_unlock(&bqlocks[queue]); 3209 free(sentinel, M_TEMP); 3210 return (flushed); 3211 } 3212 3213 /* 3214 * Check to see if a block is currently memory resident. 3215 */ 3216 struct buf * 3217 incore(struct bufobj *bo, daddr_t blkno) 3218 { 3219 struct buf *bp; 3220 3221 BO_RLOCK(bo); 3222 bp = gbincore(bo, blkno); 3223 BO_RUNLOCK(bo); 3224 return (bp); 3225 } 3226 3227 /* 3228 * Returns true if no I/O is needed to access the 3229 * associated VM object. This is like incore except 3230 * it also hunts around in the VM system for the data. 3231 */ 3232 3233 static int 3234 inmem(struct vnode * vp, daddr_t blkno) 3235 { 3236 vm_object_t obj; 3237 vm_offset_t toff, tinc, size; 3238 vm_page_t m; 3239 vm_ooffset_t off; 3240 3241 ASSERT_VOP_LOCKED(vp, "inmem"); 3242 3243 if (incore(&vp->v_bufobj, blkno)) 3244 return 1; 3245 if (vp->v_mount == NULL) 3246 return 0; 3247 obj = vp->v_object; 3248 if (obj == NULL) 3249 return (0); 3250 3251 size = PAGE_SIZE; 3252 if (size > vp->v_mount->mnt_stat.f_iosize) 3253 size = vp->v_mount->mnt_stat.f_iosize; 3254 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 3255 3256 VM_OBJECT_RLOCK(obj); 3257 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 3258 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 3259 if (!m) 3260 goto notinmem; 3261 tinc = size; 3262 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 3263 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 3264 if (vm_page_is_valid(m, 3265 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 3266 goto notinmem; 3267 } 3268 VM_OBJECT_RUNLOCK(obj); 3269 return 1; 3270 3271 notinmem: 3272 VM_OBJECT_RUNLOCK(obj); 3273 return (0); 3274 } 3275 3276 /* 3277 * Set the dirty range for a buffer based on the status of the dirty 3278 * bits in the pages comprising the buffer. The range is limited 3279 * to the size of the buffer. 3280 * 3281 * Tell the VM system that the pages associated with this buffer 3282 * are clean. This is used for delayed writes where the data is 3283 * going to go to disk eventually without additional VM intevention. 3284 * 3285 * Note that while we only really need to clean through to b_bcount, we 3286 * just go ahead and clean through to b_bufsize. 3287 */ 3288 static void 3289 vfs_clean_pages_dirty_buf(struct buf *bp) 3290 { 3291 vm_ooffset_t foff, noff, eoff; 3292 vm_page_t m; 3293 int i; 3294 3295 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 3296 return; 3297 3298 foff = bp->b_offset; 3299 KASSERT(bp->b_offset != NOOFFSET, 3300 ("vfs_clean_pages_dirty_buf: no buffer offset")); 3301 3302 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 3303 vfs_drain_busy_pages(bp); 3304 vfs_setdirty_locked_object(bp); 3305 for (i = 0; i < bp->b_npages; i++) { 3306 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3307 eoff = noff; 3308 if (eoff > bp->b_offset + bp->b_bufsize) 3309 eoff = bp->b_offset + bp->b_bufsize; 3310 m = bp->b_pages[i]; 3311 vfs_page_set_validclean(bp, foff, m); 3312 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3313 foff = noff; 3314 } 3315 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 3316 } 3317 3318 static void 3319 vfs_setdirty_locked_object(struct buf *bp) 3320 { 3321 vm_object_t object; 3322 int i; 3323 3324 object = bp->b_bufobj->bo_object; 3325 VM_OBJECT_ASSERT_WLOCKED(object); 3326 3327 /* 3328 * We qualify the scan for modified pages on whether the 3329 * object has been flushed yet. 3330 */ 3331 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) { 3332 vm_offset_t boffset; 3333 vm_offset_t eoffset; 3334 3335 /* 3336 * test the pages to see if they have been modified directly 3337 * by users through the VM system. 3338 */ 3339 for (i = 0; i < bp->b_npages; i++) 3340 vm_page_test_dirty(bp->b_pages[i]); 3341 3342 /* 3343 * Calculate the encompassing dirty range, boffset and eoffset, 3344 * (eoffset - boffset) bytes. 3345 */ 3346 3347 for (i = 0; i < bp->b_npages; i++) { 3348 if (bp->b_pages[i]->dirty) 3349 break; 3350 } 3351 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3352 3353 for (i = bp->b_npages - 1; i >= 0; --i) { 3354 if (bp->b_pages[i]->dirty) { 3355 break; 3356 } 3357 } 3358 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3359 3360 /* 3361 * Fit it to the buffer. 3362 */ 3363 3364 if (eoffset > bp->b_bcount) 3365 eoffset = bp->b_bcount; 3366 3367 /* 3368 * If we have a good dirty range, merge with the existing 3369 * dirty range. 3370 */ 3371 3372 if (boffset < eoffset) { 3373 if (bp->b_dirtyoff > boffset) 3374 bp->b_dirtyoff = boffset; 3375 if (bp->b_dirtyend < eoffset) 3376 bp->b_dirtyend = eoffset; 3377 } 3378 } 3379 } 3380 3381 /* 3382 * Allocate the KVA mapping for an existing buffer. 3383 * If an unmapped buffer is provided but a mapped buffer is requested, take 3384 * also care to properly setup mappings between pages and KVA. 3385 */ 3386 static void 3387 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags) 3388 { 3389 int bsize, maxsize, need_mapping, need_kva; 3390 off_t offset; 3391 3392 need_mapping = bp->b_data == unmapped_buf && 3393 (gbflags & GB_UNMAPPED) == 0; 3394 need_kva = bp->b_kvabase == unmapped_buf && 3395 bp->b_data == unmapped_buf && 3396 (gbflags & GB_KVAALLOC) != 0; 3397 if (!need_mapping && !need_kva) 3398 return; 3399 3400 BUF_CHECK_UNMAPPED(bp); 3401 3402 if (need_mapping && bp->b_kvabase != unmapped_buf) { 3403 /* 3404 * Buffer is not mapped, but the KVA was already 3405 * reserved at the time of the instantiation. Use the 3406 * allocated space. 3407 */ 3408 goto has_addr; 3409 } 3410 3411 /* 3412 * Calculate the amount of the address space we would reserve 3413 * if the buffer was mapped. 3414 */ 3415 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize; 3416 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3417 offset = blkno * bsize; 3418 maxsize = size + (offset & PAGE_MASK); 3419 maxsize = imax(maxsize, bsize); 3420 3421 while (bufkva_alloc(bp, maxsize, gbflags) != 0) { 3422 if ((gbflags & GB_NOWAIT_BD) != 0) { 3423 /* 3424 * XXXKIB: defragmentation cannot 3425 * succeed, not sure what else to do. 3426 */ 3427 panic("GB_NOWAIT_BD and GB_UNMAPPED %p", bp); 3428 } 3429 atomic_add_int(&mappingrestarts, 1); 3430 bufspace_wait(bp->b_vp, gbflags, 0, 0); 3431 } 3432 has_addr: 3433 if (need_mapping) { 3434 /* b_offset is handled by bpmap_qenter. */ 3435 bp->b_data = bp->b_kvabase; 3436 BUF_CHECK_MAPPED(bp); 3437 bpmap_qenter(bp); 3438 } 3439 } 3440 3441 /* 3442 * getblk: 3443 * 3444 * Get a block given a specified block and offset into a file/device. 3445 * The buffers B_DONE bit will be cleared on return, making it almost 3446 * ready for an I/O initiation. B_INVAL may or may not be set on 3447 * return. The caller should clear B_INVAL prior to initiating a 3448 * READ. 3449 * 3450 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 3451 * an existing buffer. 3452 * 3453 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 3454 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 3455 * and then cleared based on the backing VM. If the previous buffer is 3456 * non-0-sized but invalid, B_CACHE will be cleared. 3457 * 3458 * If getblk() must create a new buffer, the new buffer is returned with 3459 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 3460 * case it is returned with B_INVAL clear and B_CACHE set based on the 3461 * backing VM. 3462 * 3463 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 3464 * B_CACHE bit is clear. 3465 * 3466 * What this means, basically, is that the caller should use B_CACHE to 3467 * determine whether the buffer is fully valid or not and should clear 3468 * B_INVAL prior to issuing a read. If the caller intends to validate 3469 * the buffer by loading its data area with something, the caller needs 3470 * to clear B_INVAL. If the caller does this without issuing an I/O, 3471 * the caller should set B_CACHE ( as an optimization ), else the caller 3472 * should issue the I/O and biodone() will set B_CACHE if the I/O was 3473 * a write attempt or if it was a successful read. If the caller 3474 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 3475 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 3476 */ 3477 struct buf * 3478 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3479 int flags) 3480 { 3481 struct buf *bp; 3482 struct bufobj *bo; 3483 int bsize, error, maxsize, vmio; 3484 off_t offset; 3485 3486 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 3487 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3488 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3489 ASSERT_VOP_LOCKED(vp, "getblk"); 3490 if (size > MAXBCACHEBUF) 3491 panic("getblk: size(%d) > MAXBCACHEBUF(%d)\n", size, 3492 MAXBCACHEBUF); 3493 if (!unmapped_buf_allowed) 3494 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3495 3496 bo = &vp->v_bufobj; 3497 loop: 3498 BO_RLOCK(bo); 3499 bp = gbincore(bo, blkno); 3500 if (bp != NULL) { 3501 int lockflags; 3502 /* 3503 * Buffer is in-core. If the buffer is not busy nor managed, 3504 * it must be on a queue. 3505 */ 3506 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 3507 3508 if (flags & GB_LOCK_NOWAIT) 3509 lockflags |= LK_NOWAIT; 3510 3511 error = BUF_TIMELOCK(bp, lockflags, 3512 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo); 3513 3514 /* 3515 * If we slept and got the lock we have to restart in case 3516 * the buffer changed identities. 3517 */ 3518 if (error == ENOLCK) 3519 goto loop; 3520 /* We timed out or were interrupted. */ 3521 else if (error) 3522 return (NULL); 3523 /* If recursed, assume caller knows the rules. */ 3524 else if (BUF_LOCKRECURSED(bp)) 3525 goto end; 3526 3527 /* 3528 * The buffer is locked. B_CACHE is cleared if the buffer is 3529 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 3530 * and for a VMIO buffer B_CACHE is adjusted according to the 3531 * backing VM cache. 3532 */ 3533 if (bp->b_flags & B_INVAL) 3534 bp->b_flags &= ~B_CACHE; 3535 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 3536 bp->b_flags |= B_CACHE; 3537 if (bp->b_flags & B_MANAGED) 3538 MPASS(bp->b_qindex == QUEUE_NONE); 3539 else 3540 bremfree(bp); 3541 3542 /* 3543 * check for size inconsistencies for non-VMIO case. 3544 */ 3545 if (bp->b_bcount != size) { 3546 if ((bp->b_flags & B_VMIO) == 0 || 3547 (size > bp->b_kvasize)) { 3548 if (bp->b_flags & B_DELWRI) { 3549 bp->b_flags |= B_NOCACHE; 3550 bwrite(bp); 3551 } else { 3552 if (LIST_EMPTY(&bp->b_dep)) { 3553 bp->b_flags |= B_RELBUF; 3554 brelse(bp); 3555 } else { 3556 bp->b_flags |= B_NOCACHE; 3557 bwrite(bp); 3558 } 3559 } 3560 goto loop; 3561 } 3562 } 3563 3564 /* 3565 * Handle the case of unmapped buffer which should 3566 * become mapped, or the buffer for which KVA 3567 * reservation is requested. 3568 */ 3569 bp_unmapped_get_kva(bp, blkno, size, flags); 3570 3571 /* 3572 * If the size is inconsistent in the VMIO case, we can resize 3573 * the buffer. This might lead to B_CACHE getting set or 3574 * cleared. If the size has not changed, B_CACHE remains 3575 * unchanged from its previous state. 3576 */ 3577 allocbuf(bp, size); 3578 3579 KASSERT(bp->b_offset != NOOFFSET, 3580 ("getblk: no buffer offset")); 3581 3582 /* 3583 * A buffer with B_DELWRI set and B_CACHE clear must 3584 * be committed before we can return the buffer in 3585 * order to prevent the caller from issuing a read 3586 * ( due to B_CACHE not being set ) and overwriting 3587 * it. 3588 * 3589 * Most callers, including NFS and FFS, need this to 3590 * operate properly either because they assume they 3591 * can issue a read if B_CACHE is not set, or because 3592 * ( for example ) an uncached B_DELWRI might loop due 3593 * to softupdates re-dirtying the buffer. In the latter 3594 * case, B_CACHE is set after the first write completes, 3595 * preventing further loops. 3596 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 3597 * above while extending the buffer, we cannot allow the 3598 * buffer to remain with B_CACHE set after the write 3599 * completes or it will represent a corrupt state. To 3600 * deal with this we set B_NOCACHE to scrap the buffer 3601 * after the write. 3602 * 3603 * We might be able to do something fancy, like setting 3604 * B_CACHE in bwrite() except if B_DELWRI is already set, 3605 * so the below call doesn't set B_CACHE, but that gets real 3606 * confusing. This is much easier. 3607 */ 3608 3609 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 3610 bp->b_flags |= B_NOCACHE; 3611 bwrite(bp); 3612 goto loop; 3613 } 3614 bp->b_flags &= ~B_DONE; 3615 } else { 3616 /* 3617 * Buffer is not in-core, create new buffer. The buffer 3618 * returned by getnewbuf() is locked. Note that the returned 3619 * buffer is also considered valid (not marked B_INVAL). 3620 */ 3621 BO_RUNLOCK(bo); 3622 /* 3623 * If the user does not want us to create the buffer, bail out 3624 * here. 3625 */ 3626 if (flags & GB_NOCREAT) 3627 return NULL; 3628 if (numfreebuffers == 0 && TD_IS_IDLETHREAD(curthread)) 3629 return NULL; 3630 3631 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize; 3632 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3633 offset = blkno * bsize; 3634 vmio = vp->v_object != NULL; 3635 if (vmio) { 3636 maxsize = size + (offset & PAGE_MASK); 3637 } else { 3638 maxsize = size; 3639 /* Do not allow non-VMIO notmapped buffers. */ 3640 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3641 } 3642 maxsize = imax(maxsize, bsize); 3643 3644 bp = getnewbuf(vp, slpflag, slptimeo, maxsize, flags); 3645 if (bp == NULL) { 3646 if (slpflag || slptimeo) 3647 return NULL; 3648 /* 3649 * XXX This is here until the sleep path is diagnosed 3650 * enough to work under very low memory conditions. 3651 * 3652 * There's an issue on low memory, 4BSD+non-preempt 3653 * systems (eg MIPS routers with 32MB RAM) where buffer 3654 * exhaustion occurs without sleeping for buffer 3655 * reclaimation. This just sticks in a loop and 3656 * constantly attempts to allocate a buffer, which 3657 * hits exhaustion and tries to wakeup bufdaemon. 3658 * This never happens because we never yield. 3659 * 3660 * The real solution is to identify and fix these cases 3661 * so we aren't effectively busy-waiting in a loop 3662 * until the reclaimation path has cycles to run. 3663 */ 3664 kern_yield(PRI_USER); 3665 goto loop; 3666 } 3667 3668 /* 3669 * This code is used to make sure that a buffer is not 3670 * created while the getnewbuf routine is blocked. 3671 * This can be a problem whether the vnode is locked or not. 3672 * If the buffer is created out from under us, we have to 3673 * throw away the one we just created. 3674 * 3675 * Note: this must occur before we associate the buffer 3676 * with the vp especially considering limitations in 3677 * the splay tree implementation when dealing with duplicate 3678 * lblkno's. 3679 */ 3680 BO_LOCK(bo); 3681 if (gbincore(bo, blkno)) { 3682 BO_UNLOCK(bo); 3683 bp->b_flags |= B_INVAL; 3684 brelse(bp); 3685 bufspace_release(maxsize); 3686 goto loop; 3687 } 3688 3689 /* 3690 * Insert the buffer into the hash, so that it can 3691 * be found by incore. 3692 */ 3693 bp->b_blkno = bp->b_lblkno = blkno; 3694 bp->b_offset = offset; 3695 bgetvp(vp, bp); 3696 BO_UNLOCK(bo); 3697 3698 /* 3699 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 3700 * buffer size starts out as 0, B_CACHE will be set by 3701 * allocbuf() for the VMIO case prior to it testing the 3702 * backing store for validity. 3703 */ 3704 3705 if (vmio) { 3706 bp->b_flags |= B_VMIO; 3707 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 3708 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 3709 bp, vp->v_object, bp->b_bufobj->bo_object)); 3710 } else { 3711 bp->b_flags &= ~B_VMIO; 3712 KASSERT(bp->b_bufobj->bo_object == NULL, 3713 ("ARGH! has b_bufobj->bo_object %p %p\n", 3714 bp, bp->b_bufobj->bo_object)); 3715 BUF_CHECK_MAPPED(bp); 3716 } 3717 3718 allocbuf(bp, size); 3719 bufspace_release(maxsize); 3720 bp->b_flags &= ~B_DONE; 3721 } 3722 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 3723 BUF_ASSERT_HELD(bp); 3724 end: 3725 buf_track(bp, __func__); 3726 KASSERT(bp->b_bufobj == bo, 3727 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 3728 return (bp); 3729 } 3730 3731 /* 3732 * Get an empty, disassociated buffer of given size. The buffer is initially 3733 * set to B_INVAL. 3734 */ 3735 struct buf * 3736 geteblk(int size, int flags) 3737 { 3738 struct buf *bp; 3739 int maxsize; 3740 3741 maxsize = (size + BKVAMASK) & ~BKVAMASK; 3742 while ((bp = getnewbuf(NULL, 0, 0, maxsize, flags)) == NULL) { 3743 if ((flags & GB_NOWAIT_BD) && 3744 (curthread->td_pflags & TDP_BUFNEED) != 0) 3745 return (NULL); 3746 } 3747 allocbuf(bp, size); 3748 bufspace_release(maxsize); 3749 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 3750 BUF_ASSERT_HELD(bp); 3751 return (bp); 3752 } 3753 3754 /* 3755 * Truncate the backing store for a non-vmio buffer. 3756 */ 3757 static void 3758 vfs_nonvmio_truncate(struct buf *bp, int newbsize) 3759 { 3760 3761 if (bp->b_flags & B_MALLOC) { 3762 /* 3763 * malloced buffers are not shrunk 3764 */ 3765 if (newbsize == 0) { 3766 bufmallocadjust(bp, 0); 3767 free(bp->b_data, M_BIOBUF); 3768 bp->b_data = bp->b_kvabase; 3769 bp->b_flags &= ~B_MALLOC; 3770 } 3771 return; 3772 } 3773 vm_hold_free_pages(bp, newbsize); 3774 bufspace_adjust(bp, newbsize); 3775 } 3776 3777 /* 3778 * Extend the backing for a non-VMIO buffer. 3779 */ 3780 static void 3781 vfs_nonvmio_extend(struct buf *bp, int newbsize) 3782 { 3783 caddr_t origbuf; 3784 int origbufsize; 3785 3786 /* 3787 * We only use malloced memory on the first allocation. 3788 * and revert to page-allocated memory when the buffer 3789 * grows. 3790 * 3791 * There is a potential smp race here that could lead 3792 * to bufmallocspace slightly passing the max. It 3793 * is probably extremely rare and not worth worrying 3794 * over. 3795 */ 3796 if (bp->b_bufsize == 0 && newbsize <= PAGE_SIZE/2 && 3797 bufmallocspace < maxbufmallocspace) { 3798 bp->b_data = malloc(newbsize, M_BIOBUF, M_WAITOK); 3799 bp->b_flags |= B_MALLOC; 3800 bufmallocadjust(bp, newbsize); 3801 return; 3802 } 3803 3804 /* 3805 * If the buffer is growing on its other-than-first 3806 * allocation then we revert to the page-allocation 3807 * scheme. 3808 */ 3809 origbuf = NULL; 3810 origbufsize = 0; 3811 if (bp->b_flags & B_MALLOC) { 3812 origbuf = bp->b_data; 3813 origbufsize = bp->b_bufsize; 3814 bp->b_data = bp->b_kvabase; 3815 bufmallocadjust(bp, 0); 3816 bp->b_flags &= ~B_MALLOC; 3817 newbsize = round_page(newbsize); 3818 } 3819 vm_hold_load_pages(bp, (vm_offset_t) bp->b_data + bp->b_bufsize, 3820 (vm_offset_t) bp->b_data + newbsize); 3821 if (origbuf != NULL) { 3822 bcopy(origbuf, bp->b_data, origbufsize); 3823 free(origbuf, M_BIOBUF); 3824 } 3825 bufspace_adjust(bp, newbsize); 3826 } 3827 3828 /* 3829 * This code constitutes the buffer memory from either anonymous system 3830 * memory (in the case of non-VMIO operations) or from an associated 3831 * VM object (in the case of VMIO operations). This code is able to 3832 * resize a buffer up or down. 3833 * 3834 * Note that this code is tricky, and has many complications to resolve 3835 * deadlock or inconsistent data situations. Tread lightly!!! 3836 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 3837 * the caller. Calling this code willy nilly can result in the loss of data. 3838 * 3839 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 3840 * B_CACHE for the non-VMIO case. 3841 */ 3842 int 3843 allocbuf(struct buf *bp, int size) 3844 { 3845 int newbsize; 3846 3847 BUF_ASSERT_HELD(bp); 3848 3849 if (bp->b_bcount == size) 3850 return (1); 3851 3852 if (bp->b_kvasize != 0 && bp->b_kvasize < size) 3853 panic("allocbuf: buffer too small"); 3854 3855 newbsize = roundup2(size, DEV_BSIZE); 3856 if ((bp->b_flags & B_VMIO) == 0) { 3857 if ((bp->b_flags & B_MALLOC) == 0) 3858 newbsize = round_page(newbsize); 3859 /* 3860 * Just get anonymous memory from the kernel. Don't 3861 * mess with B_CACHE. 3862 */ 3863 if (newbsize < bp->b_bufsize) 3864 vfs_nonvmio_truncate(bp, newbsize); 3865 else if (newbsize > bp->b_bufsize) 3866 vfs_nonvmio_extend(bp, newbsize); 3867 } else { 3868 int desiredpages; 3869 3870 desiredpages = (size == 0) ? 0 : 3871 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 3872 3873 if (bp->b_flags & B_MALLOC) 3874 panic("allocbuf: VMIO buffer can't be malloced"); 3875 /* 3876 * Set B_CACHE initially if buffer is 0 length or will become 3877 * 0-length. 3878 */ 3879 if (size == 0 || bp->b_bufsize == 0) 3880 bp->b_flags |= B_CACHE; 3881 3882 if (newbsize < bp->b_bufsize) 3883 vfs_vmio_truncate(bp, desiredpages); 3884 /* XXX This looks as if it should be newbsize > b_bufsize */ 3885 else if (size > bp->b_bcount) 3886 vfs_vmio_extend(bp, desiredpages, size); 3887 bufspace_adjust(bp, newbsize); 3888 } 3889 bp->b_bcount = size; /* requested buffer size. */ 3890 return (1); 3891 } 3892 3893 extern int inflight_transient_maps; 3894 3895 void 3896 biodone(struct bio *bp) 3897 { 3898 struct mtx *mtxp; 3899 void (*done)(struct bio *); 3900 vm_offset_t start, end; 3901 3902 biotrack(bp, __func__); 3903 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) { 3904 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING; 3905 bp->bio_flags |= BIO_UNMAPPED; 3906 start = trunc_page((vm_offset_t)bp->bio_data); 3907 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length); 3908 bp->bio_data = unmapped_buf; 3909 pmap_qremove(start, OFF_TO_IDX(end - start)); 3910 vmem_free(transient_arena, start, end - start); 3911 atomic_add_int(&inflight_transient_maps, -1); 3912 } 3913 done = bp->bio_done; 3914 if (done == NULL) { 3915 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3916 mtx_lock(mtxp); 3917 bp->bio_flags |= BIO_DONE; 3918 wakeup(bp); 3919 mtx_unlock(mtxp); 3920 } else { 3921 bp->bio_flags |= BIO_DONE; 3922 done(bp); 3923 } 3924 } 3925 3926 /* 3927 * Wait for a BIO to finish. 3928 */ 3929 int 3930 biowait(struct bio *bp, const char *wchan) 3931 { 3932 struct mtx *mtxp; 3933 3934 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3935 mtx_lock(mtxp); 3936 while ((bp->bio_flags & BIO_DONE) == 0) 3937 msleep(bp, mtxp, PRIBIO, wchan, 0); 3938 mtx_unlock(mtxp); 3939 if (bp->bio_error != 0) 3940 return (bp->bio_error); 3941 if (!(bp->bio_flags & BIO_ERROR)) 3942 return (0); 3943 return (EIO); 3944 } 3945 3946 void 3947 biofinish(struct bio *bp, struct devstat *stat, int error) 3948 { 3949 3950 if (error) { 3951 bp->bio_error = error; 3952 bp->bio_flags |= BIO_ERROR; 3953 } 3954 if (stat != NULL) 3955 devstat_end_transaction_bio(stat, bp); 3956 biodone(bp); 3957 } 3958 3959 #if defined(BUF_TRACKING) || defined(FULL_BUF_TRACKING) 3960 void 3961 biotrack_buf(struct bio *bp, const char *location) 3962 { 3963 3964 buf_track(bp->bio_track_bp, location); 3965 } 3966 #endif 3967 3968 /* 3969 * bufwait: 3970 * 3971 * Wait for buffer I/O completion, returning error status. The buffer 3972 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3973 * error and cleared. 3974 */ 3975 int 3976 bufwait(struct buf *bp) 3977 { 3978 if (bp->b_iocmd == BIO_READ) 3979 bwait(bp, PRIBIO, "biord"); 3980 else 3981 bwait(bp, PRIBIO, "biowr"); 3982 if (bp->b_flags & B_EINTR) { 3983 bp->b_flags &= ~B_EINTR; 3984 return (EINTR); 3985 } 3986 if (bp->b_ioflags & BIO_ERROR) { 3987 return (bp->b_error ? bp->b_error : EIO); 3988 } else { 3989 return (0); 3990 } 3991 } 3992 3993 /* 3994 * bufdone: 3995 * 3996 * Finish I/O on a buffer, optionally calling a completion function. 3997 * This is usually called from an interrupt so process blocking is 3998 * not allowed. 3999 * 4000 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 4001 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 4002 * assuming B_INVAL is clear. 4003 * 4004 * For the VMIO case, we set B_CACHE if the op was a read and no 4005 * read error occurred, or if the op was a write. B_CACHE is never 4006 * set if the buffer is invalid or otherwise uncacheable. 4007 * 4008 * biodone does not mess with B_INVAL, allowing the I/O routine or the 4009 * initiator to leave B_INVAL set to brelse the buffer out of existence 4010 * in the biodone routine. 4011 */ 4012 void 4013 bufdone(struct buf *bp) 4014 { 4015 struct bufobj *dropobj; 4016 void (*biodone)(struct buf *); 4017 4018 buf_track(bp, __func__); 4019 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 4020 dropobj = NULL; 4021 4022 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 4023 BUF_ASSERT_HELD(bp); 4024 4025 runningbufwakeup(bp); 4026 if (bp->b_iocmd == BIO_WRITE) 4027 dropobj = bp->b_bufobj; 4028 /* call optional completion function if requested */ 4029 if (bp->b_iodone != NULL) { 4030 biodone = bp->b_iodone; 4031 bp->b_iodone = NULL; 4032 (*biodone) (bp); 4033 if (dropobj) 4034 bufobj_wdrop(dropobj); 4035 return; 4036 } 4037 4038 bufdone_finish(bp); 4039 4040 if (dropobj) 4041 bufobj_wdrop(dropobj); 4042 } 4043 4044 void 4045 bufdone_finish(struct buf *bp) 4046 { 4047 BUF_ASSERT_HELD(bp); 4048 4049 if (!LIST_EMPTY(&bp->b_dep)) 4050 buf_complete(bp); 4051 4052 if (bp->b_flags & B_VMIO) { 4053 /* 4054 * Set B_CACHE if the op was a normal read and no error 4055 * occurred. B_CACHE is set for writes in the b*write() 4056 * routines. 4057 */ 4058 if (bp->b_iocmd == BIO_READ && 4059 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 4060 !(bp->b_ioflags & BIO_ERROR)) 4061 bp->b_flags |= B_CACHE; 4062 vfs_vmio_iodone(bp); 4063 } 4064 4065 /* 4066 * For asynchronous completions, release the buffer now. The brelse 4067 * will do a wakeup there if necessary - so no need to do a wakeup 4068 * here in the async case. The sync case always needs to do a wakeup. 4069 */ 4070 if (bp->b_flags & B_ASYNC) { 4071 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || 4072 (bp->b_ioflags & BIO_ERROR)) 4073 brelse(bp); 4074 else 4075 bqrelse(bp); 4076 } else 4077 bdone(bp); 4078 } 4079 4080 /* 4081 * This routine is called in lieu of iodone in the case of 4082 * incomplete I/O. This keeps the busy status for pages 4083 * consistent. 4084 */ 4085 void 4086 vfs_unbusy_pages(struct buf *bp) 4087 { 4088 int i; 4089 vm_object_t obj; 4090 vm_page_t m; 4091 4092 runningbufwakeup(bp); 4093 if (!(bp->b_flags & B_VMIO)) 4094 return; 4095 4096 obj = bp->b_bufobj->bo_object; 4097 VM_OBJECT_WLOCK(obj); 4098 for (i = 0; i < bp->b_npages; i++) { 4099 m = bp->b_pages[i]; 4100 if (m == bogus_page) { 4101 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 4102 if (!m) 4103 panic("vfs_unbusy_pages: page missing\n"); 4104 bp->b_pages[i] = m; 4105 if (buf_mapped(bp)) { 4106 BUF_CHECK_MAPPED(bp); 4107 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4108 bp->b_pages, bp->b_npages); 4109 } else 4110 BUF_CHECK_UNMAPPED(bp); 4111 } 4112 vm_page_sunbusy(m); 4113 } 4114 vm_object_pip_wakeupn(obj, bp->b_npages); 4115 VM_OBJECT_WUNLOCK(obj); 4116 } 4117 4118 /* 4119 * vfs_page_set_valid: 4120 * 4121 * Set the valid bits in a page based on the supplied offset. The 4122 * range is restricted to the buffer's size. 4123 * 4124 * This routine is typically called after a read completes. 4125 */ 4126 static void 4127 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4128 { 4129 vm_ooffset_t eoff; 4130 4131 /* 4132 * Compute the end offset, eoff, such that [off, eoff) does not span a 4133 * page boundary and eoff is not greater than the end of the buffer. 4134 * The end of the buffer, in this case, is our file EOF, not the 4135 * allocation size of the buffer. 4136 */ 4137 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 4138 if (eoff > bp->b_offset + bp->b_bcount) 4139 eoff = bp->b_offset + bp->b_bcount; 4140 4141 /* 4142 * Set valid range. This is typically the entire buffer and thus the 4143 * entire page. 4144 */ 4145 if (eoff > off) 4146 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off); 4147 } 4148 4149 /* 4150 * vfs_page_set_validclean: 4151 * 4152 * Set the valid bits and clear the dirty bits in a page based on the 4153 * supplied offset. The range is restricted to the buffer's size. 4154 */ 4155 static void 4156 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4157 { 4158 vm_ooffset_t soff, eoff; 4159 4160 /* 4161 * Start and end offsets in buffer. eoff - soff may not cross a 4162 * page boundary or cross the end of the buffer. The end of the 4163 * buffer, in this case, is our file EOF, not the allocation size 4164 * of the buffer. 4165 */ 4166 soff = off; 4167 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4168 if (eoff > bp->b_offset + bp->b_bcount) 4169 eoff = bp->b_offset + bp->b_bcount; 4170 4171 /* 4172 * Set valid range. This is typically the entire buffer and thus the 4173 * entire page. 4174 */ 4175 if (eoff > soff) { 4176 vm_page_set_validclean( 4177 m, 4178 (vm_offset_t) (soff & PAGE_MASK), 4179 (vm_offset_t) (eoff - soff) 4180 ); 4181 } 4182 } 4183 4184 /* 4185 * Ensure that all buffer pages are not exclusive busied. If any page is 4186 * exclusive busy, drain it. 4187 */ 4188 void 4189 vfs_drain_busy_pages(struct buf *bp) 4190 { 4191 vm_page_t m; 4192 int i, last_busied; 4193 4194 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object); 4195 last_busied = 0; 4196 for (i = 0; i < bp->b_npages; i++) { 4197 m = bp->b_pages[i]; 4198 if (vm_page_xbusied(m)) { 4199 for (; last_busied < i; last_busied++) 4200 vm_page_sbusy(bp->b_pages[last_busied]); 4201 while (vm_page_xbusied(m)) { 4202 vm_page_lock(m); 4203 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4204 vm_page_busy_sleep(m, "vbpage", true); 4205 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4206 } 4207 } 4208 } 4209 for (i = 0; i < last_busied; i++) 4210 vm_page_sunbusy(bp->b_pages[i]); 4211 } 4212 4213 /* 4214 * This routine is called before a device strategy routine. 4215 * It is used to tell the VM system that paging I/O is in 4216 * progress, and treat the pages associated with the buffer 4217 * almost as being exclusive busy. Also the object paging_in_progress 4218 * flag is handled to make sure that the object doesn't become 4219 * inconsistent. 4220 * 4221 * Since I/O has not been initiated yet, certain buffer flags 4222 * such as BIO_ERROR or B_INVAL may be in an inconsistent state 4223 * and should be ignored. 4224 */ 4225 void 4226 vfs_busy_pages(struct buf *bp, int clear_modify) 4227 { 4228 int i, bogus; 4229 vm_object_t obj; 4230 vm_ooffset_t foff; 4231 vm_page_t m; 4232 4233 if (!(bp->b_flags & B_VMIO)) 4234 return; 4235 4236 obj = bp->b_bufobj->bo_object; 4237 foff = bp->b_offset; 4238 KASSERT(bp->b_offset != NOOFFSET, 4239 ("vfs_busy_pages: no buffer offset")); 4240 VM_OBJECT_WLOCK(obj); 4241 vfs_drain_busy_pages(bp); 4242 if (bp->b_bufsize != 0) 4243 vfs_setdirty_locked_object(bp); 4244 bogus = 0; 4245 for (i = 0; i < bp->b_npages; i++) { 4246 m = bp->b_pages[i]; 4247 4248 if ((bp->b_flags & B_CLUSTER) == 0) { 4249 vm_object_pip_add(obj, 1); 4250 vm_page_sbusy(m); 4251 } 4252 /* 4253 * When readying a buffer for a read ( i.e 4254 * clear_modify == 0 ), it is important to do 4255 * bogus_page replacement for valid pages in 4256 * partially instantiated buffers. Partially 4257 * instantiated buffers can, in turn, occur when 4258 * reconstituting a buffer from its VM backing store 4259 * base. We only have to do this if B_CACHE is 4260 * clear ( which causes the I/O to occur in the 4261 * first place ). The replacement prevents the read 4262 * I/O from overwriting potentially dirty VM-backed 4263 * pages. XXX bogus page replacement is, uh, bogus. 4264 * It may not work properly with small-block devices. 4265 * We need to find a better way. 4266 */ 4267 if (clear_modify) { 4268 pmap_remove_write(m); 4269 vfs_page_set_validclean(bp, foff, m); 4270 } else if (m->valid == VM_PAGE_BITS_ALL && 4271 (bp->b_flags & B_CACHE) == 0) { 4272 bp->b_pages[i] = bogus_page; 4273 bogus++; 4274 } 4275 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4276 } 4277 VM_OBJECT_WUNLOCK(obj); 4278 if (bogus && buf_mapped(bp)) { 4279 BUF_CHECK_MAPPED(bp); 4280 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4281 bp->b_pages, bp->b_npages); 4282 } 4283 } 4284 4285 /* 4286 * vfs_bio_set_valid: 4287 * 4288 * Set the range within the buffer to valid. The range is 4289 * relative to the beginning of the buffer, b_offset. Note that 4290 * b_offset itself may be offset from the beginning of the first 4291 * page. 4292 */ 4293 void 4294 vfs_bio_set_valid(struct buf *bp, int base, int size) 4295 { 4296 int i, n; 4297 vm_page_t m; 4298 4299 if (!(bp->b_flags & B_VMIO)) 4300 return; 4301 4302 /* 4303 * Fixup base to be relative to beginning of first page. 4304 * Set initial n to be the maximum number of bytes in the 4305 * first page that can be validated. 4306 */ 4307 base += (bp->b_offset & PAGE_MASK); 4308 n = PAGE_SIZE - (base & PAGE_MASK); 4309 4310 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4311 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4312 m = bp->b_pages[i]; 4313 if (n > size) 4314 n = size; 4315 vm_page_set_valid_range(m, base & PAGE_MASK, n); 4316 base += n; 4317 size -= n; 4318 n = PAGE_SIZE; 4319 } 4320 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4321 } 4322 4323 /* 4324 * vfs_bio_clrbuf: 4325 * 4326 * If the specified buffer is a non-VMIO buffer, clear the entire 4327 * buffer. If the specified buffer is a VMIO buffer, clear and 4328 * validate only the previously invalid portions of the buffer. 4329 * This routine essentially fakes an I/O, so we need to clear 4330 * BIO_ERROR and B_INVAL. 4331 * 4332 * Note that while we only theoretically need to clear through b_bcount, 4333 * we go ahead and clear through b_bufsize. 4334 */ 4335 void 4336 vfs_bio_clrbuf(struct buf *bp) 4337 { 4338 int i, j, mask, sa, ea, slide; 4339 4340 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 4341 clrbuf(bp); 4342 return; 4343 } 4344 bp->b_flags &= ~B_INVAL; 4345 bp->b_ioflags &= ~BIO_ERROR; 4346 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4347 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 4348 (bp->b_offset & PAGE_MASK) == 0) { 4349 if (bp->b_pages[0] == bogus_page) 4350 goto unlock; 4351 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 4352 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object); 4353 if ((bp->b_pages[0]->valid & mask) == mask) 4354 goto unlock; 4355 if ((bp->b_pages[0]->valid & mask) == 0) { 4356 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize); 4357 bp->b_pages[0]->valid |= mask; 4358 goto unlock; 4359 } 4360 } 4361 sa = bp->b_offset & PAGE_MASK; 4362 slide = 0; 4363 for (i = 0; i < bp->b_npages; i++, sa = 0) { 4364 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize); 4365 ea = slide & PAGE_MASK; 4366 if (ea == 0) 4367 ea = PAGE_SIZE; 4368 if (bp->b_pages[i] == bogus_page) 4369 continue; 4370 j = sa / DEV_BSIZE; 4371 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 4372 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object); 4373 if ((bp->b_pages[i]->valid & mask) == mask) 4374 continue; 4375 if ((bp->b_pages[i]->valid & mask) == 0) 4376 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa); 4377 else { 4378 for (; sa < ea; sa += DEV_BSIZE, j++) { 4379 if ((bp->b_pages[i]->valid & (1 << j)) == 0) { 4380 pmap_zero_page_area(bp->b_pages[i], 4381 sa, DEV_BSIZE); 4382 } 4383 } 4384 } 4385 bp->b_pages[i]->valid |= mask; 4386 } 4387 unlock: 4388 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4389 bp->b_resid = 0; 4390 } 4391 4392 void 4393 vfs_bio_bzero_buf(struct buf *bp, int base, int size) 4394 { 4395 vm_page_t m; 4396 int i, n; 4397 4398 if (buf_mapped(bp)) { 4399 BUF_CHECK_MAPPED(bp); 4400 bzero(bp->b_data + base, size); 4401 } else { 4402 BUF_CHECK_UNMAPPED(bp); 4403 n = PAGE_SIZE - (base & PAGE_MASK); 4404 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4405 m = bp->b_pages[i]; 4406 if (n > size) 4407 n = size; 4408 pmap_zero_page_area(m, base & PAGE_MASK, n); 4409 base += n; 4410 size -= n; 4411 n = PAGE_SIZE; 4412 } 4413 } 4414 } 4415 4416 /* 4417 * Update buffer flags based on I/O request parameters, optionally releasing the 4418 * buffer. If it's VMIO or direct I/O, the buffer pages are released to the VM, 4419 * where they may be placed on a page queue (VMIO) or freed immediately (direct 4420 * I/O). Otherwise the buffer is released to the cache. 4421 */ 4422 static void 4423 b_io_dismiss(struct buf *bp, int ioflag, bool release) 4424 { 4425 4426 KASSERT((ioflag & IO_NOREUSE) == 0 || (ioflag & IO_VMIO) != 0, 4427 ("buf %p non-VMIO noreuse", bp)); 4428 4429 if ((ioflag & IO_DIRECT) != 0) 4430 bp->b_flags |= B_DIRECT; 4431 if ((ioflag & (IO_VMIO | IO_DIRECT)) != 0 && LIST_EMPTY(&bp->b_dep)) { 4432 bp->b_flags |= B_RELBUF; 4433 if ((ioflag & IO_NOREUSE) != 0) 4434 bp->b_flags |= B_NOREUSE; 4435 if (release) 4436 brelse(bp); 4437 } else if (release) 4438 bqrelse(bp); 4439 } 4440 4441 void 4442 vfs_bio_brelse(struct buf *bp, int ioflag) 4443 { 4444 4445 b_io_dismiss(bp, ioflag, true); 4446 } 4447 4448 void 4449 vfs_bio_set_flags(struct buf *bp, int ioflag) 4450 { 4451 4452 b_io_dismiss(bp, ioflag, false); 4453 } 4454 4455 /* 4456 * vm_hold_load_pages and vm_hold_free_pages get pages into 4457 * a buffers address space. The pages are anonymous and are 4458 * not associated with a file object. 4459 */ 4460 static void 4461 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4462 { 4463 vm_offset_t pg; 4464 vm_page_t p; 4465 int index; 4466 4467 BUF_CHECK_MAPPED(bp); 4468 4469 to = round_page(to); 4470 from = round_page(from); 4471 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4472 4473 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 4474 tryagain: 4475 /* 4476 * note: must allocate system pages since blocking here 4477 * could interfere with paging I/O, no matter which 4478 * process we are. 4479 */ 4480 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ | 4481 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT)); 4482 if (p == NULL) { 4483 VM_WAIT; 4484 goto tryagain; 4485 } 4486 pmap_qenter(pg, &p, 1); 4487 bp->b_pages[index] = p; 4488 } 4489 bp->b_npages = index; 4490 } 4491 4492 /* Return pages associated with this buf to the vm system */ 4493 static void 4494 vm_hold_free_pages(struct buf *bp, int newbsize) 4495 { 4496 vm_offset_t from; 4497 vm_page_t p; 4498 int index, newnpages; 4499 4500 BUF_CHECK_MAPPED(bp); 4501 4502 from = round_page((vm_offset_t)bp->b_data + newbsize); 4503 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4504 if (bp->b_npages > newnpages) 4505 pmap_qremove(from, bp->b_npages - newnpages); 4506 for (index = newnpages; index < bp->b_npages; index++) { 4507 p = bp->b_pages[index]; 4508 bp->b_pages[index] = NULL; 4509 if (vm_page_sbusied(p)) 4510 printf("vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 4511 (intmax_t)bp->b_blkno, (intmax_t)bp->b_lblkno); 4512 p->wire_count--; 4513 vm_page_free(p); 4514 atomic_subtract_int(&vm_cnt.v_wire_count, 1); 4515 } 4516 bp->b_npages = newnpages; 4517 } 4518 4519 /* 4520 * Map an IO request into kernel virtual address space. 4521 * 4522 * All requests are (re)mapped into kernel VA space. 4523 * Notice that we use b_bufsize for the size of the buffer 4524 * to be mapped. b_bcount might be modified by the driver. 4525 * 4526 * Note that even if the caller determines that the address space should 4527 * be valid, a race or a smaller-file mapped into a larger space may 4528 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 4529 * check the return value. 4530 * 4531 * This function only works with pager buffers. 4532 */ 4533 int 4534 vmapbuf(struct buf *bp, int mapbuf) 4535 { 4536 vm_prot_t prot; 4537 int pidx; 4538 4539 if (bp->b_bufsize < 0) 4540 return (-1); 4541 prot = VM_PROT_READ; 4542 if (bp->b_iocmd == BIO_READ) 4543 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 4544 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 4545 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages, 4546 btoc(MAXPHYS))) < 0) 4547 return (-1); 4548 bp->b_npages = pidx; 4549 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK; 4550 if (mapbuf || !unmapped_buf_allowed) { 4551 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_pages, pidx); 4552 bp->b_data = bp->b_kvabase + bp->b_offset; 4553 } else 4554 bp->b_data = unmapped_buf; 4555 return(0); 4556 } 4557 4558 /* 4559 * Free the io map PTEs associated with this IO operation. 4560 * We also invalidate the TLB entries and restore the original b_addr. 4561 * 4562 * This function only works with pager buffers. 4563 */ 4564 void 4565 vunmapbuf(struct buf *bp) 4566 { 4567 int npages; 4568 4569 npages = bp->b_npages; 4570 if (buf_mapped(bp)) 4571 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 4572 vm_page_unhold_pages(bp->b_pages, npages); 4573 4574 bp->b_data = unmapped_buf; 4575 } 4576 4577 void 4578 bdone(struct buf *bp) 4579 { 4580 struct mtx *mtxp; 4581 4582 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4583 mtx_lock(mtxp); 4584 bp->b_flags |= B_DONE; 4585 wakeup(bp); 4586 mtx_unlock(mtxp); 4587 } 4588 4589 void 4590 bwait(struct buf *bp, u_char pri, const char *wchan) 4591 { 4592 struct mtx *mtxp; 4593 4594 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4595 mtx_lock(mtxp); 4596 while ((bp->b_flags & B_DONE) == 0) 4597 msleep(bp, mtxp, pri, wchan, 0); 4598 mtx_unlock(mtxp); 4599 } 4600 4601 int 4602 bufsync(struct bufobj *bo, int waitfor) 4603 { 4604 4605 return (VOP_FSYNC(bo2vnode(bo), waitfor, curthread)); 4606 } 4607 4608 void 4609 bufstrategy(struct bufobj *bo, struct buf *bp) 4610 { 4611 int i = 0; 4612 struct vnode *vp; 4613 4614 vp = bp->b_vp; 4615 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 4616 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 4617 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 4618 i = VOP_STRATEGY(vp, bp); 4619 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 4620 } 4621 4622 void 4623 bufobj_wrefl(struct bufobj *bo) 4624 { 4625 4626 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4627 ASSERT_BO_WLOCKED(bo); 4628 bo->bo_numoutput++; 4629 } 4630 4631 void 4632 bufobj_wref(struct bufobj *bo) 4633 { 4634 4635 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4636 BO_LOCK(bo); 4637 bo->bo_numoutput++; 4638 BO_UNLOCK(bo); 4639 } 4640 4641 void 4642 bufobj_wdrop(struct bufobj *bo) 4643 { 4644 4645 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 4646 BO_LOCK(bo); 4647 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 4648 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 4649 bo->bo_flag &= ~BO_WWAIT; 4650 wakeup(&bo->bo_numoutput); 4651 } 4652 BO_UNLOCK(bo); 4653 } 4654 4655 int 4656 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 4657 { 4658 int error; 4659 4660 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 4661 ASSERT_BO_WLOCKED(bo); 4662 error = 0; 4663 while (bo->bo_numoutput) { 4664 bo->bo_flag |= BO_WWAIT; 4665 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo), 4666 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 4667 if (error) 4668 break; 4669 } 4670 return (error); 4671 } 4672 4673 /* 4674 * Set bio_data or bio_ma for struct bio from the struct buf. 4675 */ 4676 void 4677 bdata2bio(struct buf *bp, struct bio *bip) 4678 { 4679 4680 if (!buf_mapped(bp)) { 4681 KASSERT(unmapped_buf_allowed, ("unmapped")); 4682 bip->bio_ma = bp->b_pages; 4683 bip->bio_ma_n = bp->b_npages; 4684 bip->bio_data = unmapped_buf; 4685 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 4686 bip->bio_flags |= BIO_UNMAPPED; 4687 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) / 4688 PAGE_SIZE == bp->b_npages, 4689 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset, 4690 (long long)bip->bio_length, bip->bio_ma_n)); 4691 } else { 4692 bip->bio_data = bp->b_data; 4693 bip->bio_ma = NULL; 4694 } 4695 } 4696 4697 /* 4698 * The MIPS pmap code currently doesn't handle aliased pages. 4699 * The VIPT caches may not handle page aliasing themselves, leading 4700 * to data corruption. 4701 * 4702 * As such, this code makes a system extremely unhappy if said 4703 * system doesn't support unaliasing the above situation in hardware. 4704 * Some "recent" systems (eg some mips24k/mips74k cores) don't enable 4705 * this feature at build time, so it has to be handled in software. 4706 * 4707 * Once the MIPS pmap/cache code grows to support this function on 4708 * earlier chips, it should be flipped back off. 4709 */ 4710 #ifdef __mips__ 4711 static int buf_pager_relbuf = 1; 4712 #else 4713 static int buf_pager_relbuf = 0; 4714 #endif 4715 SYSCTL_INT(_vfs, OID_AUTO, buf_pager_relbuf, CTLFLAG_RWTUN, 4716 &buf_pager_relbuf, 0, 4717 "Make buffer pager release buffers after reading"); 4718 4719 /* 4720 * The buffer pager. It uses buffer reads to validate pages. 4721 * 4722 * In contrast to the generic local pager from vm/vnode_pager.c, this 4723 * pager correctly and easily handles volumes where the underlying 4724 * device block size is greater than the machine page size. The 4725 * buffer cache transparently extends the requested page run to be 4726 * aligned at the block boundary, and does the necessary bogus page 4727 * replacements in the addends to avoid obliterating already valid 4728 * pages. 4729 * 4730 * The only non-trivial issue is that the exclusive busy state for 4731 * pages, which is assumed by the vm_pager_getpages() interface, is 4732 * incompatible with the VMIO buffer cache's desire to share-busy the 4733 * pages. This function performs a trivial downgrade of the pages' 4734 * state before reading buffers, and a less trivial upgrade from the 4735 * shared-busy to excl-busy state after the read. 4736 */ 4737 int 4738 vfs_bio_getpages(struct vnode *vp, vm_page_t *ma, int count, 4739 int *rbehind, int *rahead, vbg_get_lblkno_t get_lblkno, 4740 vbg_get_blksize_t get_blksize) 4741 { 4742 vm_page_t m; 4743 vm_object_t object; 4744 struct buf *bp; 4745 struct mount *mp; 4746 daddr_t lbn, lbnp; 4747 vm_ooffset_t la, lb, poff, poffe; 4748 long bsize; 4749 int bo_bs, br_flags, error, i, pgsin, pgsin_a, pgsin_b; 4750 bool redo, lpart; 4751 4752 object = vp->v_object; 4753 mp = vp->v_mount; 4754 la = IDX_TO_OFF(ma[count - 1]->pindex); 4755 if (la >= object->un_pager.vnp.vnp_size) 4756 return (VM_PAGER_BAD); 4757 lpart = la + PAGE_SIZE > object->un_pager.vnp.vnp_size; 4758 bo_bs = get_blksize(vp, get_lblkno(vp, IDX_TO_OFF(ma[0]->pindex))); 4759 4760 /* 4761 * Calculate read-ahead, behind and total pages. 4762 */ 4763 pgsin = count; 4764 lb = IDX_TO_OFF(ma[0]->pindex); 4765 pgsin_b = OFF_TO_IDX(lb - rounddown2(lb, bo_bs)); 4766 pgsin += pgsin_b; 4767 if (rbehind != NULL) 4768 *rbehind = pgsin_b; 4769 pgsin_a = OFF_TO_IDX(roundup2(la, bo_bs) - la); 4770 if (la + IDX_TO_OFF(pgsin_a) >= object->un_pager.vnp.vnp_size) 4771 pgsin_a = OFF_TO_IDX(roundup2(object->un_pager.vnp.vnp_size, 4772 PAGE_SIZE) - la); 4773 pgsin += pgsin_a; 4774 if (rahead != NULL) 4775 *rahead = pgsin_a; 4776 PCPU_INC(cnt.v_vnodein); 4777 PCPU_ADD(cnt.v_vnodepgsin, pgsin); 4778 4779 br_flags = (mp != NULL && (mp->mnt_kern_flag & MNTK_UNMAPPED_BUFS) 4780 != 0) ? GB_UNMAPPED : 0; 4781 VM_OBJECT_WLOCK(object); 4782 again: 4783 for (i = 0; i < count; i++) 4784 vm_page_busy_downgrade(ma[i]); 4785 VM_OBJECT_WUNLOCK(object); 4786 4787 lbnp = -1; 4788 for (i = 0; i < count; i++) { 4789 m = ma[i]; 4790 4791 /* 4792 * Pages are shared busy and the object lock is not 4793 * owned, which together allow for the pages' 4794 * invalidation. The racy test for validity avoids 4795 * useless creation of the buffer for the most typical 4796 * case when invalidation is not used in redo or for 4797 * parallel read. The shared->excl upgrade loop at 4798 * the end of the function catches the race in a 4799 * reliable way (protected by the object lock). 4800 */ 4801 if (m->valid == VM_PAGE_BITS_ALL) 4802 continue; 4803 4804 poff = IDX_TO_OFF(m->pindex); 4805 poffe = MIN(poff + PAGE_SIZE, object->un_pager.vnp.vnp_size); 4806 for (; poff < poffe; poff += bsize) { 4807 lbn = get_lblkno(vp, poff); 4808 if (lbn == lbnp) 4809 goto next_page; 4810 lbnp = lbn; 4811 4812 bsize = get_blksize(vp, lbn); 4813 error = bread_gb(vp, lbn, bsize, curthread->td_ucred, 4814 br_flags, &bp); 4815 if (error != 0) 4816 goto end_pages; 4817 if (LIST_EMPTY(&bp->b_dep)) { 4818 /* 4819 * Invalidation clears m->valid, but 4820 * may leave B_CACHE flag if the 4821 * buffer existed at the invalidation 4822 * time. In this case, recycle the 4823 * buffer to do real read on next 4824 * bread() after redo. 4825 * 4826 * Otherwise B_RELBUF is not strictly 4827 * necessary, enable to reduce buf 4828 * cache pressure. 4829 */ 4830 if (buf_pager_relbuf || 4831 m->valid != VM_PAGE_BITS_ALL) 4832 bp->b_flags |= B_RELBUF; 4833 4834 bp->b_flags &= ~B_NOCACHE; 4835 brelse(bp); 4836 } else { 4837 bqrelse(bp); 4838 } 4839 } 4840 KASSERT(1 /* racy, enable for debugging */ || 4841 m->valid == VM_PAGE_BITS_ALL || i == count - 1, 4842 ("buf %d %p invalid", i, m)); 4843 if (i == count - 1 && lpart) { 4844 VM_OBJECT_WLOCK(object); 4845 if (m->valid != 0 && 4846 m->valid != VM_PAGE_BITS_ALL) 4847 vm_page_zero_invalid(m, TRUE); 4848 VM_OBJECT_WUNLOCK(object); 4849 } 4850 next_page:; 4851 } 4852 end_pages: 4853 4854 VM_OBJECT_WLOCK(object); 4855 redo = false; 4856 for (i = 0; i < count; i++) { 4857 vm_page_sunbusy(ma[i]); 4858 ma[i] = vm_page_grab(object, ma[i]->pindex, VM_ALLOC_NORMAL); 4859 4860 /* 4861 * Since the pages were only sbusy while neither the 4862 * buffer nor the object lock was held by us, or 4863 * reallocated while vm_page_grab() slept for busy 4864 * relinguish, they could have been invalidated. 4865 * Recheck the valid bits and re-read as needed. 4866 * 4867 * Note that the last page is made fully valid in the 4868 * read loop, and partial validity for the page at 4869 * index count - 1 could mean that the page was 4870 * invalidated or removed, so we must restart for 4871 * safety as well. 4872 */ 4873 if (ma[i]->valid != VM_PAGE_BITS_ALL) 4874 redo = true; 4875 } 4876 if (redo && error == 0) 4877 goto again; 4878 VM_OBJECT_WUNLOCK(object); 4879 return (error != 0 ? VM_PAGER_ERROR : VM_PAGER_OK); 4880 } 4881 4882 #include "opt_ddb.h" 4883 #ifdef DDB 4884 #include <ddb/ddb.h> 4885 4886 /* DDB command to show buffer data */ 4887 DB_SHOW_COMMAND(buffer, db_show_buffer) 4888 { 4889 /* get args */ 4890 struct buf *bp = (struct buf *)addr; 4891 #ifdef FULL_BUF_TRACKING 4892 uint32_t i, j; 4893 #endif 4894 4895 if (!have_addr) { 4896 db_printf("usage: show buffer <addr>\n"); 4897 return; 4898 } 4899 4900 db_printf("buf at %p\n", bp); 4901 db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n", 4902 (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags, 4903 PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS); 4904 db_printf( 4905 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 4906 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, " 4907 "b_dep = %p\n", 4908 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 4909 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 4910 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first); 4911 db_printf("b_kvabase = %p, b_kvasize = %d\n", 4912 bp->b_kvabase, bp->b_kvasize); 4913 if (bp->b_npages) { 4914 int i; 4915 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 4916 for (i = 0; i < bp->b_npages; i++) { 4917 vm_page_t m; 4918 m = bp->b_pages[i]; 4919 if (m != NULL) 4920 db_printf("(%p, 0x%lx, 0x%lx)", m->object, 4921 (u_long)m->pindex, 4922 (u_long)VM_PAGE_TO_PHYS(m)); 4923 else 4924 db_printf("( ??? )"); 4925 if ((i + 1) < bp->b_npages) 4926 db_printf(","); 4927 } 4928 db_printf("\n"); 4929 } 4930 #if defined(FULL_BUF_TRACKING) 4931 db_printf("b_io_tracking: b_io_tcnt = %u\n", bp->b_io_tcnt); 4932 4933 i = bp->b_io_tcnt % BUF_TRACKING_SIZE; 4934 for (j = 1; j <= BUF_TRACKING_SIZE; j++) 4935 db_printf(" %2u: %s\n", j, 4936 bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)]); 4937 #elif defined(BUF_TRACKING) 4938 db_printf("b_io_tracking: %s\n", bp->b_io_tracking); 4939 #endif 4940 db_printf(" "); 4941 BUF_LOCKPRINTINFO(bp); 4942 } 4943 4944 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 4945 { 4946 struct buf *bp; 4947 int i; 4948 4949 for (i = 0; i < nbuf; i++) { 4950 bp = &buf[i]; 4951 if (BUF_ISLOCKED(bp)) { 4952 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4953 db_printf("\n"); 4954 } 4955 } 4956 } 4957 4958 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 4959 { 4960 struct vnode *vp; 4961 struct buf *bp; 4962 4963 if (!have_addr) { 4964 db_printf("usage: show vnodebufs <addr>\n"); 4965 return; 4966 } 4967 vp = (struct vnode *)addr; 4968 db_printf("Clean buffers:\n"); 4969 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 4970 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4971 db_printf("\n"); 4972 } 4973 db_printf("Dirty buffers:\n"); 4974 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 4975 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4976 db_printf("\n"); 4977 } 4978 } 4979 4980 DB_COMMAND(countfreebufs, db_coundfreebufs) 4981 { 4982 struct buf *bp; 4983 int i, used = 0, nfree = 0; 4984 4985 if (have_addr) { 4986 db_printf("usage: countfreebufs\n"); 4987 return; 4988 } 4989 4990 for (i = 0; i < nbuf; i++) { 4991 bp = &buf[i]; 4992 if (bp->b_qindex == QUEUE_EMPTY) 4993 nfree++; 4994 else 4995 used++; 4996 } 4997 4998 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 4999 nfree + used); 5000 db_printf("numfreebuffers is %d\n", numfreebuffers); 5001 } 5002 #endif /* DDB */ 5003