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 * Synchronization (sleep/wakeup) variable for active buffer space requests. 292 * Set when wait starts, cleared prior to wakeup(). 293 * Used in runningbufwakeup() and waitrunningbufspace(). 294 */ 295 static int runningbufreq; 296 297 /* 298 * Synchronization (sleep/wakeup) variable for buffer requests. 299 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done 300 * by and/or. 301 * Used in numdirtywakeup(), bufspace_wakeup(), bwillwrite(), 302 * getnewbuf(), and getblk(). 303 */ 304 static volatile int needsbuffer; 305 306 /* 307 * Synchronization for bwillwrite() waiters. 308 */ 309 static int bdirtywait; 310 311 /* 312 * Definitions for the buffer free lists. 313 */ 314 #define QUEUE_NONE 0 /* on no queue */ 315 #define QUEUE_EMPTY 1 /* empty buffer headers */ 316 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */ 317 #define QUEUE_CLEAN 3 /* non-B_DELWRI buffers */ 318 #define QUEUE_SENTINEL 1024 /* not an queue index, but mark for sentinel */ 319 320 /* Maximum number of clean buffer queues. */ 321 #define CLEAN_QUEUES 16 322 323 /* Configured number of clean queues. */ 324 static int clean_queues; 325 326 /* Maximum number of buffer queues. */ 327 #define BUFFER_QUEUES (QUEUE_CLEAN + CLEAN_QUEUES) 328 329 /* Queues for free buffers with various properties */ 330 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } }; 331 #ifdef INVARIANTS 332 static int bq_len[BUFFER_QUEUES]; 333 #endif 334 335 /* 336 * Lock for each bufqueue 337 */ 338 static struct mtx_padalign bqlocks[BUFFER_QUEUES]; 339 340 /* 341 * per-cpu empty buffer cache. 342 */ 343 uma_zone_t buf_zone; 344 345 /* 346 * Single global constant for BUF_WMESG, to avoid getting multiple references. 347 * buf_wmesg is referred from macros. 348 */ 349 const char *buf_wmesg = BUF_WMESG; 350 351 static int 352 sysctl_runningspace(SYSCTL_HANDLER_ARGS) 353 { 354 long value; 355 int error; 356 357 value = *(long *)arg1; 358 error = sysctl_handle_long(oidp, &value, 0, req); 359 if (error != 0 || req->newptr == NULL) 360 return (error); 361 mtx_lock(&rbreqlock); 362 if (arg1 == &hirunningspace) { 363 if (value < lorunningspace) 364 error = EINVAL; 365 else 366 hirunningspace = value; 367 } else { 368 KASSERT(arg1 == &lorunningspace, 369 ("%s: unknown arg1", __func__)); 370 if (value > hirunningspace) 371 error = EINVAL; 372 else 373 lorunningspace = value; 374 } 375 mtx_unlock(&rbreqlock); 376 return (error); 377 } 378 379 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 380 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 381 static int 382 sysctl_bufspace(SYSCTL_HANDLER_ARGS) 383 { 384 long lvalue; 385 int ivalue; 386 387 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long)) 388 return (sysctl_handle_long(oidp, arg1, arg2, req)); 389 lvalue = *(long *)arg1; 390 if (lvalue > INT_MAX) 391 /* On overflow, still write out a long to trigger ENOMEM. */ 392 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 393 ivalue = lvalue; 394 return (sysctl_handle_int(oidp, &ivalue, 0, req)); 395 } 396 #endif 397 398 static int 399 bqcleanq(void) 400 { 401 static int nextq; 402 403 return ((atomic_fetchadd_int(&nextq, 1) % clean_queues) + QUEUE_CLEAN); 404 } 405 406 static int 407 bqisclean(int qindex) 408 { 409 410 return (qindex >= QUEUE_CLEAN && qindex < QUEUE_CLEAN + CLEAN_QUEUES); 411 } 412 413 /* 414 * bqlock: 415 * 416 * Return the appropriate queue lock based on the index. 417 */ 418 static inline struct mtx * 419 bqlock(int qindex) 420 { 421 422 return (struct mtx *)&bqlocks[qindex]; 423 } 424 425 /* 426 * bdirtywakeup: 427 * 428 * Wakeup any bwillwrite() waiters. 429 */ 430 static void 431 bdirtywakeup(void) 432 { 433 mtx_lock(&bdirtylock); 434 if (bdirtywait) { 435 bdirtywait = 0; 436 wakeup(&bdirtywait); 437 } 438 mtx_unlock(&bdirtylock); 439 } 440 441 /* 442 * bdirtysub: 443 * 444 * Decrement the numdirtybuffers count by one and wakeup any 445 * threads blocked in bwillwrite(). 446 */ 447 static void 448 bdirtysub(void) 449 { 450 451 if (atomic_fetchadd_int(&numdirtybuffers, -1) == 452 (lodirtybuffers + hidirtybuffers) / 2) 453 bdirtywakeup(); 454 } 455 456 /* 457 * bdirtyadd: 458 * 459 * Increment the numdirtybuffers count by one and wakeup the buf 460 * daemon if needed. 461 */ 462 static void 463 bdirtyadd(void) 464 { 465 466 /* 467 * Only do the wakeup once as we cross the boundary. The 468 * buf daemon will keep running until the condition clears. 469 */ 470 if (atomic_fetchadd_int(&numdirtybuffers, 1) == 471 (lodirtybuffers + hidirtybuffers) / 2) 472 bd_wakeup(); 473 } 474 475 /* 476 * bufspace_wakeup: 477 * 478 * Called when buffer space is potentially available for recovery. 479 * getnewbuf() will block on this flag when it is unable to free 480 * sufficient buffer space. Buffer space becomes recoverable when 481 * bp's get placed back in the queues. 482 */ 483 static void 484 bufspace_wakeup(void) 485 { 486 487 /* 488 * If someone is waiting for bufspace, wake them up. 489 * 490 * Since needsbuffer is set prior to doing an additional queue 491 * scan it is safe to check for the flag prior to acquiring the 492 * lock. The thread that is preparing to scan again before 493 * blocking would discover the buf we released. 494 */ 495 if (needsbuffer) { 496 rw_rlock(&nblock); 497 if (atomic_cmpset_int(&needsbuffer, 1, 0) == 1) 498 wakeup(__DEVOLATILE(void *, &needsbuffer)); 499 rw_runlock(&nblock); 500 } 501 } 502 503 /* 504 * bufspace_daemonwakeup: 505 * 506 * Wakeup the daemon responsible for freeing clean bufs. 507 */ 508 static void 509 bufspace_daemonwakeup(void) 510 { 511 rw_rlock(&nblock); 512 if (bufspace_request == 0) { 513 bufspace_request = 1; 514 wakeup(&bufspace_request); 515 } 516 rw_runlock(&nblock); 517 } 518 519 /* 520 * bufspace_adjust: 521 * 522 * Adjust the reported bufspace for a KVA managed buffer, possibly 523 * waking any waiters. 524 */ 525 static void 526 bufspace_adjust(struct buf *bp, int bufsize) 527 { 528 long space; 529 int diff; 530 531 KASSERT((bp->b_flags & B_MALLOC) == 0, 532 ("bufspace_adjust: malloc buf %p", bp)); 533 diff = bufsize - bp->b_bufsize; 534 if (diff < 0) { 535 atomic_subtract_long(&bufspace, -diff); 536 bufspace_wakeup(); 537 } else { 538 space = atomic_fetchadd_long(&bufspace, diff); 539 /* Wake up the daemon on the transition. */ 540 if (space < bufspacethresh && space + diff >= bufspacethresh) 541 bufspace_daemonwakeup(); 542 } 543 bp->b_bufsize = bufsize; 544 } 545 546 /* 547 * bufspace_reserve: 548 * 549 * Reserve bufspace before calling allocbuf(). metadata has a 550 * different space limit than data. 551 */ 552 static int 553 bufspace_reserve(int size, bool metadata) 554 { 555 long limit; 556 long space; 557 558 if (metadata) 559 limit = maxbufspace; 560 else 561 limit = hibufspace; 562 do { 563 space = bufspace; 564 if (space + size > limit) 565 return (ENOSPC); 566 } while (atomic_cmpset_long(&bufspace, space, space + size) == 0); 567 568 /* Wake up the daemon on the transition. */ 569 if (space < bufspacethresh && space + size >= bufspacethresh) 570 bufspace_daemonwakeup(); 571 572 return (0); 573 } 574 575 /* 576 * bufspace_release: 577 * 578 * Release reserved bufspace after bufspace_adjust() has consumed it. 579 */ 580 static void 581 bufspace_release(int size) 582 { 583 atomic_subtract_long(&bufspace, size); 584 bufspace_wakeup(); 585 } 586 587 /* 588 * bufspace_wait: 589 * 590 * Wait for bufspace, acting as the buf daemon if a locked vnode is 591 * supplied. needsbuffer must be set in a safe fashion prior to 592 * polling for space. The operation must be re-tried on return. 593 */ 594 static void 595 bufspace_wait(struct vnode *vp, int gbflags, int slpflag, int slptimeo) 596 { 597 struct thread *td; 598 int error, fl, norunbuf; 599 600 if ((gbflags & GB_NOWAIT_BD) != 0) 601 return; 602 603 td = curthread; 604 rw_wlock(&nblock); 605 while (needsbuffer != 0) { 606 if (vp != NULL && vp->v_type != VCHR && 607 (td->td_pflags & TDP_BUFNEED) == 0) { 608 rw_wunlock(&nblock); 609 /* 610 * getblk() is called with a vnode locked, and 611 * some majority of the dirty buffers may as 612 * well belong to the vnode. Flushing the 613 * buffers there would make a progress that 614 * cannot be achieved by the buf_daemon, that 615 * cannot lock the vnode. 616 */ 617 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) | 618 (td->td_pflags & TDP_NORUNNINGBUF); 619 620 /* 621 * Play bufdaemon. The getnewbuf() function 622 * may be called while the thread owns lock 623 * for another dirty buffer for the same 624 * vnode, which makes it impossible to use 625 * VOP_FSYNC() there, due to the buffer lock 626 * recursion. 627 */ 628 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF; 629 fl = buf_flush(vp, flushbufqtarget); 630 td->td_pflags &= norunbuf; 631 rw_wlock(&nblock); 632 if (fl != 0) 633 continue; 634 if (needsbuffer == 0) 635 break; 636 } 637 error = rw_sleep(__DEVOLATILE(void *, &needsbuffer), &nblock, 638 (PRIBIO + 4) | slpflag, "newbuf", slptimeo); 639 if (error != 0) 640 break; 641 } 642 rw_wunlock(&nblock); 643 } 644 645 646 /* 647 * bufspace_daemon: 648 * 649 * buffer space management daemon. Tries to maintain some marginal 650 * amount of free buffer space so that requesting processes neither 651 * block nor work to reclaim buffers. 652 */ 653 static void 654 bufspace_daemon(void) 655 { 656 for (;;) { 657 kproc_suspend_check(bufspacedaemonproc); 658 659 /* 660 * Free buffers from the clean queue until we meet our 661 * targets. 662 * 663 * Theory of operation: The buffer cache is most efficient 664 * when some free buffer headers and space are always 665 * available to getnewbuf(). This daemon attempts to prevent 666 * the excessive blocking and synchronization associated 667 * with shortfall. It goes through three phases according 668 * demand: 669 * 670 * 1) The daemon wakes up voluntarily once per-second 671 * during idle periods when the counters are below 672 * the wakeup thresholds (bufspacethresh, lofreebuffers). 673 * 674 * 2) The daemon wakes up as we cross the thresholds 675 * ahead of any potential blocking. This may bounce 676 * slightly according to the rate of consumption and 677 * release. 678 * 679 * 3) The daemon and consumers are starved for working 680 * clean buffers. This is the 'bufspace' sleep below 681 * which will inefficiently trade bufs with bqrelse 682 * until we return to condition 2. 683 */ 684 while (bufspace > lobufspace || 685 numfreebuffers < hifreebuffers) { 686 if (buf_recycle(false) != 0) { 687 atomic_set_int(&needsbuffer, 1); 688 if (buf_recycle(false) != 0) { 689 rw_wlock(&nblock); 690 if (needsbuffer) 691 rw_sleep(__DEVOLATILE(void *, 692 &needsbuffer), &nblock, 693 PRIBIO|PDROP, "bufspace", 694 hz/10); 695 else 696 rw_wunlock(&nblock); 697 } 698 } 699 maybe_yield(); 700 } 701 702 /* 703 * Re-check our limits under the exclusive nblock. 704 */ 705 rw_wlock(&nblock); 706 if (bufspace < bufspacethresh && 707 numfreebuffers > lofreebuffers) { 708 bufspace_request = 0; 709 rw_sleep(&bufspace_request, &nblock, PRIBIO|PDROP, 710 "-", hz); 711 } else 712 rw_wunlock(&nblock); 713 } 714 } 715 716 static struct kproc_desc bufspace_kp = { 717 "bufspacedaemon", 718 bufspace_daemon, 719 &bufspacedaemonproc 720 }; 721 SYSINIT(bufspacedaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, 722 &bufspace_kp); 723 724 /* 725 * bufmallocadjust: 726 * 727 * Adjust the reported bufspace for a malloc managed buffer, possibly 728 * waking any waiters. 729 */ 730 static void 731 bufmallocadjust(struct buf *bp, int bufsize) 732 { 733 int diff; 734 735 KASSERT((bp->b_flags & B_MALLOC) != 0, 736 ("bufmallocadjust: non-malloc buf %p", bp)); 737 diff = bufsize - bp->b_bufsize; 738 if (diff < 0) 739 atomic_subtract_long(&bufmallocspace, -diff); 740 else 741 atomic_add_long(&bufmallocspace, diff); 742 bp->b_bufsize = bufsize; 743 } 744 745 /* 746 * runningwakeup: 747 * 748 * Wake up processes that are waiting on asynchronous writes to fall 749 * below lorunningspace. 750 */ 751 static void 752 runningwakeup(void) 753 { 754 755 mtx_lock(&rbreqlock); 756 if (runningbufreq) { 757 runningbufreq = 0; 758 wakeup(&runningbufreq); 759 } 760 mtx_unlock(&rbreqlock); 761 } 762 763 /* 764 * runningbufwakeup: 765 * 766 * Decrement the outstanding write count according. 767 */ 768 void 769 runningbufwakeup(struct buf *bp) 770 { 771 long space, bspace; 772 773 bspace = bp->b_runningbufspace; 774 if (bspace == 0) 775 return; 776 space = atomic_fetchadd_long(&runningbufspace, -bspace); 777 KASSERT(space >= bspace, ("runningbufspace underflow %ld %ld", 778 space, bspace)); 779 bp->b_runningbufspace = 0; 780 /* 781 * Only acquire the lock and wakeup on the transition from exceeding 782 * the threshold to falling below it. 783 */ 784 if (space < lorunningspace) 785 return; 786 if (space - bspace > lorunningspace) 787 return; 788 runningwakeup(); 789 } 790 791 /* 792 * waitrunningbufspace() 793 * 794 * runningbufspace is a measure of the amount of I/O currently 795 * running. This routine is used in async-write situations to 796 * prevent creating huge backups of pending writes to a device. 797 * Only asynchronous writes are governed by this function. 798 * 799 * This does NOT turn an async write into a sync write. It waits 800 * for earlier writes to complete and generally returns before the 801 * caller's write has reached the device. 802 */ 803 void 804 waitrunningbufspace(void) 805 { 806 807 mtx_lock(&rbreqlock); 808 while (runningbufspace > hirunningspace) { 809 runningbufreq = 1; 810 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 811 } 812 mtx_unlock(&rbreqlock); 813 } 814 815 816 /* 817 * vfs_buf_test_cache: 818 * 819 * Called when a buffer is extended. This function clears the B_CACHE 820 * bit if the newly extended portion of the buffer does not contain 821 * valid data. 822 */ 823 static __inline void 824 vfs_buf_test_cache(struct buf *bp, vm_ooffset_t foff, vm_offset_t off, 825 vm_offset_t size, vm_page_t m) 826 { 827 828 VM_OBJECT_ASSERT_LOCKED(m->object); 829 if (bp->b_flags & B_CACHE) { 830 int base = (foff + off) & PAGE_MASK; 831 if (vm_page_is_valid(m, base, size) == 0) 832 bp->b_flags &= ~B_CACHE; 833 } 834 } 835 836 /* Wake up the buffer daemon if necessary */ 837 static __inline void 838 bd_wakeup(void) 839 { 840 841 mtx_lock(&bdlock); 842 if (bd_request == 0) { 843 bd_request = 1; 844 wakeup(&bd_request); 845 } 846 mtx_unlock(&bdlock); 847 } 848 849 /* 850 * bd_speedup - speedup the buffer cache flushing code 851 */ 852 void 853 bd_speedup(void) 854 { 855 int needwake; 856 857 mtx_lock(&bdlock); 858 needwake = 0; 859 if (bd_speedupreq == 0 || bd_request == 0) 860 needwake = 1; 861 bd_speedupreq = 1; 862 bd_request = 1; 863 if (needwake) 864 wakeup(&bd_request); 865 mtx_unlock(&bdlock); 866 } 867 868 #ifndef NSWBUF_MIN 869 #define NSWBUF_MIN 16 870 #endif 871 872 #ifdef __i386__ 873 #define TRANSIENT_DENOM 5 874 #else 875 #define TRANSIENT_DENOM 10 876 #endif 877 878 /* 879 * Calculating buffer cache scaling values and reserve space for buffer 880 * headers. This is called during low level kernel initialization and 881 * may be called more then once. We CANNOT write to the memory area 882 * being reserved at this time. 883 */ 884 caddr_t 885 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 886 { 887 int tuned_nbuf; 888 long maxbuf, maxbuf_sz, buf_sz, biotmap_sz; 889 890 /* 891 * physmem_est is in pages. Convert it to kilobytes (assumes 892 * PAGE_SIZE is >= 1K) 893 */ 894 physmem_est = physmem_est * (PAGE_SIZE / 1024); 895 896 /* 897 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 898 * For the first 64MB of ram nominally allocate sufficient buffers to 899 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 900 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing 901 * the buffer cache we limit the eventual kva reservation to 902 * maxbcache bytes. 903 * 904 * factor represents the 1/4 x ram conversion. 905 */ 906 if (nbuf == 0) { 907 int factor = 4 * BKVASIZE / 1024; 908 909 nbuf = 50; 910 if (physmem_est > 4096) 911 nbuf += min((physmem_est - 4096) / factor, 912 65536 / factor); 913 if (physmem_est > 65536) 914 nbuf += min((physmem_est - 65536) * 2 / (factor * 5), 915 32 * 1024 * 1024 / (factor * 5)); 916 917 if (maxbcache && nbuf > maxbcache / BKVASIZE) 918 nbuf = maxbcache / BKVASIZE; 919 tuned_nbuf = 1; 920 } else 921 tuned_nbuf = 0; 922 923 /* XXX Avoid unsigned long overflows later on with maxbufspace. */ 924 maxbuf = (LONG_MAX / 3) / BKVASIZE; 925 if (nbuf > maxbuf) { 926 if (!tuned_nbuf) 927 printf("Warning: nbufs lowered from %d to %ld\n", nbuf, 928 maxbuf); 929 nbuf = maxbuf; 930 } 931 932 /* 933 * Ideal allocation size for the transient bio submap is 10% 934 * of the maximal space buffer map. This roughly corresponds 935 * to the amount of the buffer mapped for typical UFS load. 936 * 937 * Clip the buffer map to reserve space for the transient 938 * BIOs, if its extent is bigger than 90% (80% on i386) of the 939 * maximum buffer map extent on the platform. 940 * 941 * The fall-back to the maxbuf in case of maxbcache unset, 942 * allows to not trim the buffer KVA for the architectures 943 * with ample KVA space. 944 */ 945 if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) { 946 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE; 947 buf_sz = (long)nbuf * BKVASIZE; 948 if (buf_sz < maxbuf_sz / TRANSIENT_DENOM * 949 (TRANSIENT_DENOM - 1)) { 950 /* 951 * There is more KVA than memory. Do not 952 * adjust buffer map size, and assign the rest 953 * of maxbuf to transient map. 954 */ 955 biotmap_sz = maxbuf_sz - buf_sz; 956 } else { 957 /* 958 * Buffer map spans all KVA we could afford on 959 * this platform. Give 10% (20% on i386) of 960 * the buffer map to the transient bio map. 961 */ 962 biotmap_sz = buf_sz / TRANSIENT_DENOM; 963 buf_sz -= biotmap_sz; 964 } 965 if (biotmap_sz / INT_MAX > MAXPHYS) 966 bio_transient_maxcnt = INT_MAX; 967 else 968 bio_transient_maxcnt = biotmap_sz / MAXPHYS; 969 /* 970 * Artificially limit to 1024 simultaneous in-flight I/Os 971 * using the transient mapping. 972 */ 973 if (bio_transient_maxcnt > 1024) 974 bio_transient_maxcnt = 1024; 975 if (tuned_nbuf) 976 nbuf = buf_sz / BKVASIZE; 977 } 978 979 /* 980 * swbufs are used as temporary holders for I/O, such as paging I/O. 981 * We have no less then 16 and no more then 256. 982 */ 983 nswbuf = min(nbuf / 4, 256); 984 TUNABLE_INT_FETCH("kern.nswbuf", &nswbuf); 985 if (nswbuf < NSWBUF_MIN) 986 nswbuf = NSWBUF_MIN; 987 988 /* 989 * Reserve space for the buffer cache buffers 990 */ 991 swbuf = (void *)v; 992 v = (caddr_t)(swbuf + nswbuf); 993 buf = (void *)v; 994 v = (caddr_t)(buf + nbuf); 995 996 return(v); 997 } 998 999 /* Initialize the buffer subsystem. Called before use of any buffers. */ 1000 void 1001 bufinit(void) 1002 { 1003 struct buf *bp; 1004 int i; 1005 1006 CTASSERT(MAXBCACHEBUF >= MAXBSIZE); 1007 mtx_init(&bqlocks[QUEUE_DIRTY], "bufq dirty lock", NULL, MTX_DEF); 1008 mtx_init(&bqlocks[QUEUE_EMPTY], "bufq empty lock", NULL, MTX_DEF); 1009 for (i = QUEUE_CLEAN; i < QUEUE_CLEAN + CLEAN_QUEUES; i++) 1010 mtx_init(&bqlocks[i], "bufq clean lock", NULL, MTX_DEF); 1011 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 1012 rw_init(&nblock, "needsbuffer lock"); 1013 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 1014 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF); 1015 1016 /* next, make a null set of free lists */ 1017 for (i = 0; i < BUFFER_QUEUES; i++) 1018 TAILQ_INIT(&bufqueues[i]); 1019 1020 unmapped_buf = (caddr_t)kva_alloc(MAXPHYS); 1021 1022 /* finally, initialize each buffer header and stick on empty q */ 1023 for (i = 0; i < nbuf; i++) { 1024 bp = &buf[i]; 1025 bzero(bp, sizeof *bp); 1026 bp->b_flags = B_INVAL; 1027 bp->b_rcred = NOCRED; 1028 bp->b_wcred = NOCRED; 1029 bp->b_qindex = QUEUE_EMPTY; 1030 bp->b_xflags = 0; 1031 bp->b_data = bp->b_kvabase = unmapped_buf; 1032 LIST_INIT(&bp->b_dep); 1033 BUF_LOCKINIT(bp); 1034 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 1035 #ifdef INVARIANTS 1036 bq_len[QUEUE_EMPTY]++; 1037 #endif 1038 } 1039 1040 /* 1041 * maxbufspace is the absolute maximum amount of buffer space we are 1042 * allowed to reserve in KVM and in real terms. The absolute maximum 1043 * is nominally used by metadata. hibufspace is the nominal maximum 1044 * used by most other requests. The differential is required to 1045 * ensure that metadata deadlocks don't occur. 1046 * 1047 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 1048 * this may result in KVM fragmentation which is not handled optimally 1049 * by the system. XXX This is less true with vmem. We could use 1050 * PAGE_SIZE. 1051 */ 1052 maxbufspace = (long)nbuf * BKVASIZE; 1053 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - MAXBCACHEBUF * 10); 1054 lobufspace = (hibufspace / 20) * 19; /* 95% */ 1055 bufspacethresh = lobufspace + (hibufspace - lobufspace) / 2; 1056 1057 /* 1058 * Note: The 16 MiB upper limit for hirunningspace was chosen 1059 * arbitrarily and may need further tuning. It corresponds to 1060 * 128 outstanding write IO requests (if IO size is 128 KiB), 1061 * which fits with many RAID controllers' tagged queuing limits. 1062 * The lower 1 MiB limit is the historical upper limit for 1063 * hirunningspace. 1064 */ 1065 hirunningspace = lmax(lmin(roundup(hibufspace / 64, MAXBCACHEBUF), 1066 16 * 1024 * 1024), 1024 * 1024); 1067 lorunningspace = roundup((hirunningspace * 2) / 3, MAXBCACHEBUF); 1068 1069 /* 1070 * Limit the amount of malloc memory since it is wired permanently into 1071 * the kernel space. Even though this is accounted for in the buffer 1072 * allocation, we don't want the malloced region to grow uncontrolled. 1073 * The malloc scheme improves memory utilization significantly on 1074 * average (small) directories. 1075 */ 1076 maxbufmallocspace = hibufspace / 20; 1077 1078 /* 1079 * Reduce the chance of a deadlock occurring by limiting the number 1080 * of delayed-write dirty buffers we allow to stack up. 1081 */ 1082 hidirtybuffers = nbuf / 4 + 20; 1083 dirtybufthresh = hidirtybuffers * 9 / 10; 1084 numdirtybuffers = 0; 1085 /* 1086 * To support extreme low-memory systems, make sure hidirtybuffers 1087 * cannot eat up all available buffer space. This occurs when our 1088 * minimum cannot be met. We try to size hidirtybuffers to 3/4 our 1089 * buffer space assuming BKVASIZE'd buffers. 1090 */ 1091 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 1092 hidirtybuffers >>= 1; 1093 } 1094 lodirtybuffers = hidirtybuffers / 2; 1095 1096 /* 1097 * lofreebuffers should be sufficient to avoid stalling waiting on 1098 * buf headers under heavy utilization. The bufs in per-cpu caches 1099 * are counted as free but will be unavailable to threads executing 1100 * on other cpus. 1101 * 1102 * hifreebuffers is the free target for the bufspace daemon. This 1103 * should be set appropriately to limit work per-iteration. 1104 */ 1105 lofreebuffers = MIN((nbuf / 25) + (20 * mp_ncpus), 128 * mp_ncpus); 1106 hifreebuffers = (3 * lofreebuffers) / 2; 1107 numfreebuffers = nbuf; 1108 1109 /* Setup the kva and free list allocators. */ 1110 vmem_set_reclaim(buffer_arena, bufkva_reclaim); 1111 buf_zone = uma_zcache_create("buf free cache", sizeof(struct buf), 1112 NULL, NULL, NULL, NULL, buf_import, buf_release, NULL, 0); 1113 1114 /* 1115 * Size the clean queue according to the amount of buffer space. 1116 * One queue per-256mb up to the max. More queues gives better 1117 * concurrency but less accurate LRU. 1118 */ 1119 clean_queues = MIN(howmany(maxbufspace, 256*1024*1024), CLEAN_QUEUES); 1120 1121 } 1122 1123 #ifdef INVARIANTS 1124 static inline void 1125 vfs_buf_check_mapped(struct buf *bp) 1126 { 1127 1128 KASSERT(bp->b_kvabase != unmapped_buf, 1129 ("mapped buf: b_kvabase was not updated %p", bp)); 1130 KASSERT(bp->b_data != unmapped_buf, 1131 ("mapped buf: b_data was not updated %p", bp)); 1132 KASSERT(bp->b_data < unmapped_buf || bp->b_data >= unmapped_buf + 1133 MAXPHYS, ("b_data + b_offset unmapped %p", bp)); 1134 } 1135 1136 static inline void 1137 vfs_buf_check_unmapped(struct buf *bp) 1138 { 1139 1140 KASSERT(bp->b_data == unmapped_buf, 1141 ("unmapped buf: corrupted b_data %p", bp)); 1142 } 1143 1144 #define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp) 1145 #define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp) 1146 #else 1147 #define BUF_CHECK_MAPPED(bp) do {} while (0) 1148 #define BUF_CHECK_UNMAPPED(bp) do {} while (0) 1149 #endif 1150 1151 static int 1152 isbufbusy(struct buf *bp) 1153 { 1154 if (((bp->b_flags & B_INVAL) == 0 && BUF_ISLOCKED(bp)) || 1155 ((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI)) 1156 return (1); 1157 return (0); 1158 } 1159 1160 /* 1161 * Shutdown the system cleanly to prepare for reboot, halt, or power off. 1162 */ 1163 void 1164 bufshutdown(int show_busybufs) 1165 { 1166 static int first_buf_printf = 1; 1167 struct buf *bp; 1168 int iter, nbusy, pbusy; 1169 #ifndef PREEMPTION 1170 int subiter; 1171 #endif 1172 1173 /* 1174 * Sync filesystems for shutdown 1175 */ 1176 wdog_kern_pat(WD_LASTVAL); 1177 sys_sync(curthread, NULL); 1178 1179 /* 1180 * With soft updates, some buffers that are 1181 * written will be remarked as dirty until other 1182 * buffers are written. 1183 */ 1184 for (iter = pbusy = 0; iter < 20; iter++) { 1185 nbusy = 0; 1186 for (bp = &buf[nbuf]; --bp >= buf; ) 1187 if (isbufbusy(bp)) 1188 nbusy++; 1189 if (nbusy == 0) { 1190 if (first_buf_printf) 1191 printf("All buffers synced."); 1192 break; 1193 } 1194 if (first_buf_printf) { 1195 printf("Syncing disks, buffers remaining... "); 1196 first_buf_printf = 0; 1197 } 1198 printf("%d ", nbusy); 1199 if (nbusy < pbusy) 1200 iter = 0; 1201 pbusy = nbusy; 1202 1203 wdog_kern_pat(WD_LASTVAL); 1204 sys_sync(curthread, NULL); 1205 1206 #ifdef PREEMPTION 1207 /* 1208 * Drop Giant and spin for a while to allow 1209 * interrupt threads to run. 1210 */ 1211 DROP_GIANT(); 1212 DELAY(50000 * iter); 1213 PICKUP_GIANT(); 1214 #else 1215 /* 1216 * Drop Giant and context switch several times to 1217 * allow interrupt threads to run. 1218 */ 1219 DROP_GIANT(); 1220 for (subiter = 0; subiter < 50 * iter; subiter++) { 1221 thread_lock(curthread); 1222 mi_switch(SW_VOL, NULL); 1223 thread_unlock(curthread); 1224 DELAY(1000); 1225 } 1226 PICKUP_GIANT(); 1227 #endif 1228 } 1229 printf("\n"); 1230 /* 1231 * Count only busy local buffers to prevent forcing 1232 * a fsck if we're just a client of a wedged NFS server 1233 */ 1234 nbusy = 0; 1235 for (bp = &buf[nbuf]; --bp >= buf; ) { 1236 if (isbufbusy(bp)) { 1237 #if 0 1238 /* XXX: This is bogus. We should probably have a BO_REMOTE flag instead */ 1239 if (bp->b_dev == NULL) { 1240 TAILQ_REMOVE(&mountlist, 1241 bp->b_vp->v_mount, mnt_list); 1242 continue; 1243 } 1244 #endif 1245 nbusy++; 1246 if (show_busybufs > 0) { 1247 printf( 1248 "%d: buf:%p, vnode:%p, flags:%0x, blkno:%jd, lblkno:%jd, buflock:", 1249 nbusy, bp, bp->b_vp, bp->b_flags, 1250 (intmax_t)bp->b_blkno, 1251 (intmax_t)bp->b_lblkno); 1252 BUF_LOCKPRINTINFO(bp); 1253 if (show_busybufs > 1) 1254 vn_printf(bp->b_vp, 1255 "vnode content: "); 1256 } 1257 } 1258 } 1259 if (nbusy) { 1260 /* 1261 * Failed to sync all blocks. Indicate this and don't 1262 * unmount filesystems (thus forcing an fsck on reboot). 1263 */ 1264 printf("Giving up on %d buffers\n", nbusy); 1265 DELAY(5000000); /* 5 seconds */ 1266 } else { 1267 if (!first_buf_printf) 1268 printf("Final sync complete\n"); 1269 /* 1270 * Unmount filesystems 1271 */ 1272 if (panicstr == NULL) 1273 vfs_unmountall(); 1274 } 1275 swapoff_all(); 1276 DELAY(100000); /* wait for console output to finish */ 1277 } 1278 1279 static void 1280 bpmap_qenter(struct buf *bp) 1281 { 1282 1283 BUF_CHECK_MAPPED(bp); 1284 1285 /* 1286 * bp->b_data is relative to bp->b_offset, but 1287 * bp->b_offset may be offset into the first page. 1288 */ 1289 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data); 1290 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages); 1291 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 1292 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 1293 } 1294 1295 /* 1296 * binsfree: 1297 * 1298 * Insert the buffer into the appropriate free list. 1299 */ 1300 static void 1301 binsfree(struct buf *bp, int qindex) 1302 { 1303 struct mtx *olock, *nlock; 1304 1305 if (qindex != QUEUE_EMPTY) { 1306 BUF_ASSERT_XLOCKED(bp); 1307 } 1308 1309 /* 1310 * Stick to the same clean queue for the lifetime of the buf to 1311 * limit locking below. Otherwise pick ont sequentially. 1312 */ 1313 if (qindex == QUEUE_CLEAN) { 1314 if (bqisclean(bp->b_qindex)) 1315 qindex = bp->b_qindex; 1316 else 1317 qindex = bqcleanq(); 1318 } 1319 1320 /* 1321 * Handle delayed bremfree() processing. 1322 */ 1323 nlock = bqlock(qindex); 1324 if (bp->b_flags & B_REMFREE) { 1325 olock = bqlock(bp->b_qindex); 1326 mtx_lock(olock); 1327 bremfreel(bp); 1328 if (olock != nlock) { 1329 mtx_unlock(olock); 1330 mtx_lock(nlock); 1331 } 1332 } else 1333 mtx_lock(nlock); 1334 1335 if (bp->b_qindex != QUEUE_NONE) 1336 panic("binsfree: free buffer onto another queue???"); 1337 1338 bp->b_qindex = qindex; 1339 if (bp->b_flags & B_AGE) 1340 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1341 else 1342 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1343 #ifdef INVARIANTS 1344 bq_len[bp->b_qindex]++; 1345 #endif 1346 mtx_unlock(nlock); 1347 } 1348 1349 /* 1350 * buf_free: 1351 * 1352 * Free a buffer to the buf zone once it no longer has valid contents. 1353 */ 1354 static void 1355 buf_free(struct buf *bp) 1356 { 1357 1358 if (bp->b_flags & B_REMFREE) 1359 bremfreef(bp); 1360 if (bp->b_vflags & BV_BKGRDINPROG) 1361 panic("losing buffer 1"); 1362 if (bp->b_rcred != NOCRED) { 1363 crfree(bp->b_rcred); 1364 bp->b_rcred = NOCRED; 1365 } 1366 if (bp->b_wcred != NOCRED) { 1367 crfree(bp->b_wcred); 1368 bp->b_wcred = NOCRED; 1369 } 1370 if (!LIST_EMPTY(&bp->b_dep)) 1371 buf_deallocate(bp); 1372 bufkva_free(bp); 1373 BUF_UNLOCK(bp); 1374 uma_zfree(buf_zone, bp); 1375 atomic_add_int(&numfreebuffers, 1); 1376 bufspace_wakeup(); 1377 } 1378 1379 /* 1380 * buf_import: 1381 * 1382 * Import bufs into the uma cache from the buf list. The system still 1383 * expects a static array of bufs and much of the synchronization 1384 * around bufs assumes type stable storage. As a result, UMA is used 1385 * only as a per-cpu cache of bufs still maintained on a global list. 1386 */ 1387 static int 1388 buf_import(void *arg, void **store, int cnt, int flags) 1389 { 1390 struct buf *bp; 1391 int i; 1392 1393 mtx_lock(&bqlocks[QUEUE_EMPTY]); 1394 for (i = 0; i < cnt; i++) { 1395 bp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1396 if (bp == NULL) 1397 break; 1398 bremfreel(bp); 1399 store[i] = bp; 1400 } 1401 mtx_unlock(&bqlocks[QUEUE_EMPTY]); 1402 1403 return (i); 1404 } 1405 1406 /* 1407 * buf_release: 1408 * 1409 * Release bufs from the uma cache back to the buffer queues. 1410 */ 1411 static void 1412 buf_release(void *arg, void **store, int cnt) 1413 { 1414 int i; 1415 1416 for (i = 0; i < cnt; i++) 1417 binsfree(store[i], QUEUE_EMPTY); 1418 } 1419 1420 /* 1421 * buf_alloc: 1422 * 1423 * Allocate an empty buffer header. 1424 */ 1425 static struct buf * 1426 buf_alloc(void) 1427 { 1428 struct buf *bp; 1429 1430 bp = uma_zalloc(buf_zone, M_NOWAIT); 1431 if (bp == NULL) { 1432 bufspace_daemonwakeup(); 1433 atomic_add_int(&numbufallocfails, 1); 1434 return (NULL); 1435 } 1436 1437 /* 1438 * Wake-up the bufspace daemon on transition. 1439 */ 1440 if (atomic_fetchadd_int(&numfreebuffers, -1) == lofreebuffers) 1441 bufspace_daemonwakeup(); 1442 1443 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1444 panic("getnewbuf_empty: Locked buf %p on free queue.", bp); 1445 1446 KASSERT(bp->b_vp == NULL, 1447 ("bp: %p still has vnode %p.", bp, bp->b_vp)); 1448 KASSERT((bp->b_flags & (B_DELWRI | B_NOREUSE)) == 0, 1449 ("invalid buffer %p flags %#x", bp, bp->b_flags)); 1450 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 1451 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags)); 1452 KASSERT(bp->b_npages == 0, 1453 ("bp: %p still has %d vm pages\n", bp, bp->b_npages)); 1454 KASSERT(bp->b_kvasize == 0, ("bp: %p still has kva\n", bp)); 1455 KASSERT(bp->b_bufsize == 0, ("bp: %p still has bufspace\n", bp)); 1456 1457 bp->b_flags = 0; 1458 bp->b_ioflags = 0; 1459 bp->b_xflags = 0; 1460 bp->b_vflags = 0; 1461 bp->b_vp = NULL; 1462 bp->b_blkno = bp->b_lblkno = 0; 1463 bp->b_offset = NOOFFSET; 1464 bp->b_iodone = 0; 1465 bp->b_error = 0; 1466 bp->b_resid = 0; 1467 bp->b_bcount = 0; 1468 bp->b_npages = 0; 1469 bp->b_dirtyoff = bp->b_dirtyend = 0; 1470 bp->b_bufobj = NULL; 1471 bp->b_data = bp->b_kvabase = unmapped_buf; 1472 bp->b_fsprivate1 = NULL; 1473 bp->b_fsprivate2 = NULL; 1474 bp->b_fsprivate3 = NULL; 1475 LIST_INIT(&bp->b_dep); 1476 1477 return (bp); 1478 } 1479 1480 /* 1481 * buf_qrecycle: 1482 * 1483 * Free a buffer from the given bufqueue. kva controls whether the 1484 * freed buf must own some kva resources. This is used for 1485 * defragmenting. 1486 */ 1487 static int 1488 buf_qrecycle(int qindex, bool kva) 1489 { 1490 struct buf *bp, *nbp; 1491 1492 if (kva) 1493 atomic_add_int(&bufdefragcnt, 1); 1494 nbp = NULL; 1495 mtx_lock(&bqlocks[qindex]); 1496 nbp = TAILQ_FIRST(&bufqueues[qindex]); 1497 1498 /* 1499 * Run scan, possibly freeing data and/or kva mappings on the fly 1500 * depending. 1501 */ 1502 while ((bp = nbp) != NULL) { 1503 /* 1504 * Calculate next bp (we can only use it if we do not 1505 * release the bqlock). 1506 */ 1507 nbp = TAILQ_NEXT(bp, b_freelist); 1508 1509 /* 1510 * If we are defragging then we need a buffer with 1511 * some kva to reclaim. 1512 */ 1513 if (kva && bp->b_kvasize == 0) 1514 continue; 1515 1516 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1517 continue; 1518 1519 /* 1520 * Skip buffers with background writes in progress. 1521 */ 1522 if ((bp->b_vflags & BV_BKGRDINPROG) != 0) { 1523 BUF_UNLOCK(bp); 1524 continue; 1525 } 1526 1527 KASSERT(bp->b_qindex == qindex, 1528 ("getnewbuf: inconsistent queue %d bp %p", qindex, bp)); 1529 /* 1530 * NOTE: nbp is now entirely invalid. We can only restart 1531 * the scan from this point on. 1532 */ 1533 bremfreel(bp); 1534 mtx_unlock(&bqlocks[qindex]); 1535 1536 /* 1537 * Requeue the background write buffer with error and 1538 * restart the scan. 1539 */ 1540 if ((bp->b_vflags & BV_BKGRDERR) != 0) { 1541 bqrelse(bp); 1542 mtx_lock(&bqlocks[qindex]); 1543 nbp = TAILQ_FIRST(&bufqueues[qindex]); 1544 continue; 1545 } 1546 bp->b_flags |= B_INVAL; 1547 brelse(bp); 1548 return (0); 1549 } 1550 mtx_unlock(&bqlocks[qindex]); 1551 1552 return (ENOBUFS); 1553 } 1554 1555 /* 1556 * buf_recycle: 1557 * 1558 * Iterate through all clean queues until we find a buf to recycle or 1559 * exhaust the search. 1560 */ 1561 static int 1562 buf_recycle(bool kva) 1563 { 1564 int qindex, first_qindex; 1565 1566 qindex = first_qindex = bqcleanq(); 1567 do { 1568 if (buf_qrecycle(qindex, kva) == 0) 1569 return (0); 1570 if (++qindex == QUEUE_CLEAN + clean_queues) 1571 qindex = QUEUE_CLEAN; 1572 } while (qindex != first_qindex); 1573 1574 return (ENOBUFS); 1575 } 1576 1577 /* 1578 * buf_scan: 1579 * 1580 * Scan the clean queues looking for a buffer to recycle. needsbuffer 1581 * is set on failure so that the caller may optionally bufspace_wait() 1582 * in a race-free fashion. 1583 */ 1584 static int 1585 buf_scan(bool defrag) 1586 { 1587 int error; 1588 1589 /* 1590 * To avoid heavy synchronization and wakeup races we set 1591 * needsbuffer and re-poll before failing. This ensures that 1592 * no frees can be missed between an unsuccessful poll and 1593 * going to sleep in a synchronized fashion. 1594 */ 1595 if ((error = buf_recycle(defrag)) != 0) { 1596 atomic_set_int(&needsbuffer, 1); 1597 bufspace_daemonwakeup(); 1598 error = buf_recycle(defrag); 1599 } 1600 if (error == 0) 1601 atomic_add_int(&getnewbufrestarts, 1); 1602 return (error); 1603 } 1604 1605 /* 1606 * bremfree: 1607 * 1608 * Mark the buffer for removal from the appropriate free list. 1609 * 1610 */ 1611 void 1612 bremfree(struct buf *bp) 1613 { 1614 1615 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1616 KASSERT((bp->b_flags & B_REMFREE) == 0, 1617 ("bremfree: buffer %p already marked for delayed removal.", bp)); 1618 KASSERT(bp->b_qindex != QUEUE_NONE, 1619 ("bremfree: buffer %p not on a queue.", bp)); 1620 BUF_ASSERT_XLOCKED(bp); 1621 1622 bp->b_flags |= B_REMFREE; 1623 } 1624 1625 /* 1626 * bremfreef: 1627 * 1628 * Force an immediate removal from a free list. Used only in nfs when 1629 * it abuses the b_freelist pointer. 1630 */ 1631 void 1632 bremfreef(struct buf *bp) 1633 { 1634 struct mtx *qlock; 1635 1636 qlock = bqlock(bp->b_qindex); 1637 mtx_lock(qlock); 1638 bremfreel(bp); 1639 mtx_unlock(qlock); 1640 } 1641 1642 /* 1643 * bremfreel: 1644 * 1645 * Removes a buffer from the free list, must be called with the 1646 * correct qlock held. 1647 */ 1648 static void 1649 bremfreel(struct buf *bp) 1650 { 1651 1652 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X", 1653 bp, bp->b_vp, bp->b_flags); 1654 KASSERT(bp->b_qindex != QUEUE_NONE, 1655 ("bremfreel: buffer %p not on a queue.", bp)); 1656 if (bp->b_qindex != QUEUE_EMPTY) { 1657 BUF_ASSERT_XLOCKED(bp); 1658 } 1659 mtx_assert(bqlock(bp->b_qindex), MA_OWNED); 1660 1661 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 1662 #ifdef INVARIANTS 1663 KASSERT(bq_len[bp->b_qindex] >= 1, ("queue %d underflow", 1664 bp->b_qindex)); 1665 bq_len[bp->b_qindex]--; 1666 #endif 1667 bp->b_qindex = QUEUE_NONE; 1668 bp->b_flags &= ~B_REMFREE; 1669 } 1670 1671 /* 1672 * bufkva_free: 1673 * 1674 * Free the kva allocation for a buffer. 1675 * 1676 */ 1677 static void 1678 bufkva_free(struct buf *bp) 1679 { 1680 1681 #ifdef INVARIANTS 1682 if (bp->b_kvasize == 0) { 1683 KASSERT(bp->b_kvabase == unmapped_buf && 1684 bp->b_data == unmapped_buf, 1685 ("Leaked KVA space on %p", bp)); 1686 } else if (buf_mapped(bp)) 1687 BUF_CHECK_MAPPED(bp); 1688 else 1689 BUF_CHECK_UNMAPPED(bp); 1690 #endif 1691 if (bp->b_kvasize == 0) 1692 return; 1693 1694 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, bp->b_kvasize); 1695 atomic_subtract_long(&bufkvaspace, bp->b_kvasize); 1696 atomic_add_int(&buffreekvacnt, 1); 1697 bp->b_data = bp->b_kvabase = unmapped_buf; 1698 bp->b_kvasize = 0; 1699 } 1700 1701 /* 1702 * bufkva_alloc: 1703 * 1704 * Allocate the buffer KVA and set b_kvasize and b_kvabase. 1705 */ 1706 static int 1707 bufkva_alloc(struct buf *bp, int maxsize, int gbflags) 1708 { 1709 vm_offset_t addr; 1710 int error; 1711 1712 KASSERT((gbflags & GB_UNMAPPED) == 0 || (gbflags & GB_KVAALLOC) != 0, 1713 ("Invalid gbflags 0x%x in %s", gbflags, __func__)); 1714 1715 bufkva_free(bp); 1716 1717 addr = 0; 1718 error = vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr); 1719 if (error != 0) { 1720 /* 1721 * Buffer map is too fragmented. Request the caller 1722 * to defragment the map. 1723 */ 1724 return (error); 1725 } 1726 bp->b_kvabase = (caddr_t)addr; 1727 bp->b_kvasize = maxsize; 1728 atomic_add_long(&bufkvaspace, bp->b_kvasize); 1729 if ((gbflags & GB_UNMAPPED) != 0) { 1730 bp->b_data = unmapped_buf; 1731 BUF_CHECK_UNMAPPED(bp); 1732 } else { 1733 bp->b_data = bp->b_kvabase; 1734 BUF_CHECK_MAPPED(bp); 1735 } 1736 return (0); 1737 } 1738 1739 /* 1740 * bufkva_reclaim: 1741 * 1742 * Reclaim buffer kva by freeing buffers holding kva. This is a vmem 1743 * callback that fires to avoid returning failure. 1744 */ 1745 static void 1746 bufkva_reclaim(vmem_t *vmem, int flags) 1747 { 1748 int i; 1749 1750 for (i = 0; i < 5; i++) 1751 if (buf_scan(true) != 0) 1752 break; 1753 return; 1754 } 1755 1756 1757 /* 1758 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 1759 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 1760 * the buffer is valid and we do not have to do anything. 1761 */ 1762 void 1763 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, 1764 int cnt, struct ucred * cred) 1765 { 1766 struct buf *rabp; 1767 int i; 1768 1769 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 1770 if (inmem(vp, *rablkno)) 1771 continue; 1772 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 1773 1774 if ((rabp->b_flags & B_CACHE) == 0) { 1775 if (!TD_IS_IDLETHREAD(curthread)) { 1776 #ifdef RACCT 1777 if (racct_enable) { 1778 PROC_LOCK(curproc); 1779 racct_add_buf(curproc, rabp, 0); 1780 PROC_UNLOCK(curproc); 1781 } 1782 #endif /* RACCT */ 1783 curthread->td_ru.ru_inblock++; 1784 } 1785 rabp->b_flags |= B_ASYNC; 1786 rabp->b_flags &= ~B_INVAL; 1787 rabp->b_ioflags &= ~BIO_ERROR; 1788 rabp->b_iocmd = BIO_READ; 1789 if (rabp->b_rcred == NOCRED && cred != NOCRED) 1790 rabp->b_rcred = crhold(cred); 1791 vfs_busy_pages(rabp, 0); 1792 BUF_KERNPROC(rabp); 1793 rabp->b_iooffset = dbtob(rabp->b_blkno); 1794 bstrategy(rabp); 1795 } else { 1796 brelse(rabp); 1797 } 1798 } 1799 } 1800 1801 /* 1802 * Entry point for bread() and breadn() via #defines in sys/buf.h. 1803 * 1804 * Get a buffer with the specified data. Look in the cache first. We 1805 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 1806 * is set, the buffer is valid and we do not have to do anything, see 1807 * getblk(). Also starts asynchronous I/O on read-ahead blocks. 1808 * 1809 * Always return a NULL buffer pointer (in bpp) when returning an error. 1810 */ 1811 int 1812 breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno, 1813 int *rabsize, int cnt, struct ucred *cred, int flags, struct buf **bpp) 1814 { 1815 struct buf *bp; 1816 int rv = 0, readwait = 0; 1817 1818 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 1819 /* 1820 * Can only return NULL if GB_LOCK_NOWAIT flag is specified. 1821 */ 1822 *bpp = bp = getblk(vp, blkno, size, 0, 0, flags); 1823 if (bp == NULL) 1824 return (EBUSY); 1825 1826 /* if not found in cache, do some I/O */ 1827 if ((bp->b_flags & B_CACHE) == 0) { 1828 if (!TD_IS_IDLETHREAD(curthread)) { 1829 #ifdef RACCT 1830 if (racct_enable) { 1831 PROC_LOCK(curproc); 1832 racct_add_buf(curproc, bp, 0); 1833 PROC_UNLOCK(curproc); 1834 } 1835 #endif /* RACCT */ 1836 curthread->td_ru.ru_inblock++; 1837 } 1838 bp->b_iocmd = BIO_READ; 1839 bp->b_flags &= ~B_INVAL; 1840 bp->b_ioflags &= ~BIO_ERROR; 1841 if (bp->b_rcred == NOCRED && cred != NOCRED) 1842 bp->b_rcred = crhold(cred); 1843 vfs_busy_pages(bp, 0); 1844 bp->b_iooffset = dbtob(bp->b_blkno); 1845 bstrategy(bp); 1846 ++readwait; 1847 } 1848 1849 breada(vp, rablkno, rabsize, cnt, cred); 1850 1851 if (readwait) { 1852 rv = bufwait(bp); 1853 if (rv != 0) { 1854 brelse(bp); 1855 *bpp = NULL; 1856 } 1857 } 1858 return (rv); 1859 } 1860 1861 /* 1862 * Write, release buffer on completion. (Done by iodone 1863 * if async). Do not bother writing anything if the buffer 1864 * is invalid. 1865 * 1866 * Note that we set B_CACHE here, indicating that buffer is 1867 * fully valid and thus cacheable. This is true even of NFS 1868 * now so we set it generally. This could be set either here 1869 * or in biodone() since the I/O is synchronous. We put it 1870 * here. 1871 */ 1872 int 1873 bufwrite(struct buf *bp) 1874 { 1875 int oldflags; 1876 struct vnode *vp; 1877 long space; 1878 int vp_md; 1879 1880 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1881 if ((bp->b_bufobj->bo_flag & BO_DEAD) != 0) { 1882 bp->b_flags |= B_INVAL | B_RELBUF; 1883 bp->b_flags &= ~B_CACHE; 1884 brelse(bp); 1885 return (ENXIO); 1886 } 1887 if (bp->b_flags & B_INVAL) { 1888 brelse(bp); 1889 return (0); 1890 } 1891 1892 if (bp->b_flags & B_BARRIER) 1893 barrierwrites++; 1894 1895 oldflags = bp->b_flags; 1896 1897 BUF_ASSERT_HELD(bp); 1898 1899 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 1900 ("FFS background buffer should not get here %p", bp)); 1901 1902 vp = bp->b_vp; 1903 if (vp) 1904 vp_md = vp->v_vflag & VV_MD; 1905 else 1906 vp_md = 0; 1907 1908 /* 1909 * Mark the buffer clean. Increment the bufobj write count 1910 * before bundirty() call, to prevent other thread from seeing 1911 * empty dirty list and zero counter for writes in progress, 1912 * falsely indicating that the bufobj is clean. 1913 */ 1914 bufobj_wref(bp->b_bufobj); 1915 bundirty(bp); 1916 1917 bp->b_flags &= ~B_DONE; 1918 bp->b_ioflags &= ~BIO_ERROR; 1919 bp->b_flags |= B_CACHE; 1920 bp->b_iocmd = BIO_WRITE; 1921 1922 vfs_busy_pages(bp, 1); 1923 1924 /* 1925 * Normal bwrites pipeline writes 1926 */ 1927 bp->b_runningbufspace = bp->b_bufsize; 1928 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace); 1929 1930 if (!TD_IS_IDLETHREAD(curthread)) { 1931 #ifdef RACCT 1932 if (racct_enable) { 1933 PROC_LOCK(curproc); 1934 racct_add_buf(curproc, bp, 1); 1935 PROC_UNLOCK(curproc); 1936 } 1937 #endif /* RACCT */ 1938 curthread->td_ru.ru_oublock++; 1939 } 1940 if (oldflags & B_ASYNC) 1941 BUF_KERNPROC(bp); 1942 bp->b_iooffset = dbtob(bp->b_blkno); 1943 buf_track(bp, __func__); 1944 bstrategy(bp); 1945 1946 if ((oldflags & B_ASYNC) == 0) { 1947 int rtval = bufwait(bp); 1948 brelse(bp); 1949 return (rtval); 1950 } else if (space > hirunningspace) { 1951 /* 1952 * don't allow the async write to saturate the I/O 1953 * system. We will not deadlock here because 1954 * we are blocking waiting for I/O that is already in-progress 1955 * to complete. We do not block here if it is the update 1956 * or syncer daemon trying to clean up as that can lead 1957 * to deadlock. 1958 */ 1959 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 1960 waitrunningbufspace(); 1961 } 1962 1963 return (0); 1964 } 1965 1966 void 1967 bufbdflush(struct bufobj *bo, struct buf *bp) 1968 { 1969 struct buf *nbp; 1970 1971 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 1972 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 1973 altbufferflushes++; 1974 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 1975 BO_LOCK(bo); 1976 /* 1977 * Try to find a buffer to flush. 1978 */ 1979 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 1980 if ((nbp->b_vflags & BV_BKGRDINPROG) || 1981 BUF_LOCK(nbp, 1982 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 1983 continue; 1984 if (bp == nbp) 1985 panic("bdwrite: found ourselves"); 1986 BO_UNLOCK(bo); 1987 /* Don't countdeps with the bo lock held. */ 1988 if (buf_countdeps(nbp, 0)) { 1989 BO_LOCK(bo); 1990 BUF_UNLOCK(nbp); 1991 continue; 1992 } 1993 if (nbp->b_flags & B_CLUSTEROK) { 1994 vfs_bio_awrite(nbp); 1995 } else { 1996 bremfree(nbp); 1997 bawrite(nbp); 1998 } 1999 dirtybufferflushes++; 2000 break; 2001 } 2002 if (nbp == NULL) 2003 BO_UNLOCK(bo); 2004 } 2005 } 2006 2007 /* 2008 * Delayed write. (Buffer is marked dirty). Do not bother writing 2009 * anything if the buffer is marked invalid. 2010 * 2011 * Note that since the buffer must be completely valid, we can safely 2012 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 2013 * biodone() in order to prevent getblk from writing the buffer 2014 * out synchronously. 2015 */ 2016 void 2017 bdwrite(struct buf *bp) 2018 { 2019 struct thread *td = curthread; 2020 struct vnode *vp; 2021 struct bufobj *bo; 2022 2023 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2024 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2025 KASSERT((bp->b_flags & B_BARRIER) == 0, 2026 ("Barrier request in delayed write %p", bp)); 2027 BUF_ASSERT_HELD(bp); 2028 2029 if (bp->b_flags & B_INVAL) { 2030 brelse(bp); 2031 return; 2032 } 2033 2034 /* 2035 * If we have too many dirty buffers, don't create any more. 2036 * If we are wildly over our limit, then force a complete 2037 * cleanup. Otherwise, just keep the situation from getting 2038 * out of control. Note that we have to avoid a recursive 2039 * disaster and not try to clean up after our own cleanup! 2040 */ 2041 vp = bp->b_vp; 2042 bo = bp->b_bufobj; 2043 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 2044 td->td_pflags |= TDP_INBDFLUSH; 2045 BO_BDFLUSH(bo, bp); 2046 td->td_pflags &= ~TDP_INBDFLUSH; 2047 } else 2048 recursiveflushes++; 2049 2050 bdirty(bp); 2051 /* 2052 * Set B_CACHE, indicating that the buffer is fully valid. This is 2053 * true even of NFS now. 2054 */ 2055 bp->b_flags |= B_CACHE; 2056 2057 /* 2058 * This bmap keeps the system from needing to do the bmap later, 2059 * perhaps when the system is attempting to do a sync. Since it 2060 * is likely that the indirect block -- or whatever other datastructure 2061 * that the filesystem needs is still in memory now, it is a good 2062 * thing to do this. Note also, that if the pageout daemon is 2063 * requesting a sync -- there might not be enough memory to do 2064 * the bmap then... So, this is important to do. 2065 */ 2066 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 2067 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 2068 } 2069 2070 buf_track(bp, __func__); 2071 2072 /* 2073 * Set the *dirty* buffer range based upon the VM system dirty 2074 * pages. 2075 * 2076 * Mark the buffer pages as clean. We need to do this here to 2077 * satisfy the vnode_pager and the pageout daemon, so that it 2078 * thinks that the pages have been "cleaned". Note that since 2079 * the pages are in a delayed write buffer -- the VFS layer 2080 * "will" see that the pages get written out on the next sync, 2081 * or perhaps the cluster will be completed. 2082 */ 2083 vfs_clean_pages_dirty_buf(bp); 2084 bqrelse(bp); 2085 2086 /* 2087 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 2088 * due to the softdep code. 2089 */ 2090 } 2091 2092 /* 2093 * bdirty: 2094 * 2095 * Turn buffer into delayed write request. We must clear BIO_READ and 2096 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 2097 * itself to properly update it in the dirty/clean lists. We mark it 2098 * B_DONE to ensure that any asynchronization of the buffer properly 2099 * clears B_DONE ( else a panic will occur later ). 2100 * 2101 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 2102 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 2103 * should only be called if the buffer is known-good. 2104 * 2105 * Since the buffer is not on a queue, we do not update the numfreebuffers 2106 * count. 2107 * 2108 * The buffer must be on QUEUE_NONE. 2109 */ 2110 void 2111 bdirty(struct buf *bp) 2112 { 2113 2114 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 2115 bp, bp->b_vp, bp->b_flags); 2116 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2117 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 2118 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 2119 BUF_ASSERT_HELD(bp); 2120 bp->b_flags &= ~(B_RELBUF); 2121 bp->b_iocmd = BIO_WRITE; 2122 2123 if ((bp->b_flags & B_DELWRI) == 0) { 2124 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 2125 reassignbuf(bp); 2126 bdirtyadd(); 2127 } 2128 } 2129 2130 /* 2131 * bundirty: 2132 * 2133 * Clear B_DELWRI for buffer. 2134 * 2135 * Since the buffer is not on a queue, we do not update the numfreebuffers 2136 * count. 2137 * 2138 * The buffer must be on QUEUE_NONE. 2139 */ 2140 2141 void 2142 bundirty(struct buf *bp) 2143 { 2144 2145 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2146 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2147 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 2148 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 2149 BUF_ASSERT_HELD(bp); 2150 2151 if (bp->b_flags & B_DELWRI) { 2152 bp->b_flags &= ~B_DELWRI; 2153 reassignbuf(bp); 2154 bdirtysub(); 2155 } 2156 /* 2157 * Since it is now being written, we can clear its deferred write flag. 2158 */ 2159 bp->b_flags &= ~B_DEFERRED; 2160 } 2161 2162 /* 2163 * bawrite: 2164 * 2165 * Asynchronous write. Start output on a buffer, but do not wait for 2166 * it to complete. The buffer is released when the output completes. 2167 * 2168 * bwrite() ( or the VOP routine anyway ) is responsible for handling 2169 * B_INVAL buffers. Not us. 2170 */ 2171 void 2172 bawrite(struct buf *bp) 2173 { 2174 2175 bp->b_flags |= B_ASYNC; 2176 (void) bwrite(bp); 2177 } 2178 2179 /* 2180 * babarrierwrite: 2181 * 2182 * Asynchronous barrier write. Start output on a buffer, but do not 2183 * wait for it to complete. Place a write barrier after this write so 2184 * that this buffer and all buffers written before it are committed to 2185 * the disk before any buffers written after this write are committed 2186 * to the disk. The buffer is released when the output completes. 2187 */ 2188 void 2189 babarrierwrite(struct buf *bp) 2190 { 2191 2192 bp->b_flags |= B_ASYNC | B_BARRIER; 2193 (void) bwrite(bp); 2194 } 2195 2196 /* 2197 * bbarrierwrite: 2198 * 2199 * Synchronous barrier write. Start output on a buffer and wait for 2200 * it to complete. Place a write barrier after this write so that 2201 * this buffer and all buffers written before it are committed to 2202 * the disk before any buffers written after this write are committed 2203 * to the disk. The buffer is released when the output completes. 2204 */ 2205 int 2206 bbarrierwrite(struct buf *bp) 2207 { 2208 2209 bp->b_flags |= B_BARRIER; 2210 return (bwrite(bp)); 2211 } 2212 2213 /* 2214 * bwillwrite: 2215 * 2216 * Called prior to the locking of any vnodes when we are expecting to 2217 * write. We do not want to starve the buffer cache with too many 2218 * dirty buffers so we block here. By blocking prior to the locking 2219 * of any vnodes we attempt to avoid the situation where a locked vnode 2220 * prevents the various system daemons from flushing related buffers. 2221 */ 2222 void 2223 bwillwrite(void) 2224 { 2225 2226 if (numdirtybuffers >= hidirtybuffers) { 2227 mtx_lock(&bdirtylock); 2228 while (numdirtybuffers >= hidirtybuffers) { 2229 bdirtywait = 1; 2230 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4), 2231 "flswai", 0); 2232 } 2233 mtx_unlock(&bdirtylock); 2234 } 2235 } 2236 2237 /* 2238 * Return true if we have too many dirty buffers. 2239 */ 2240 int 2241 buf_dirty_count_severe(void) 2242 { 2243 2244 return(numdirtybuffers >= hidirtybuffers); 2245 } 2246 2247 /* 2248 * brelse: 2249 * 2250 * Release a busy buffer and, if requested, free its resources. The 2251 * buffer will be stashed in the appropriate bufqueue[] allowing it 2252 * to be accessed later as a cache entity or reused for other purposes. 2253 */ 2254 void 2255 brelse(struct buf *bp) 2256 { 2257 int qindex; 2258 2259 /* 2260 * Many functions erroneously call brelse with a NULL bp under rare 2261 * error conditions. Simply return when called with a NULL bp. 2262 */ 2263 if (bp == NULL) 2264 return; 2265 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 2266 bp, bp->b_vp, bp->b_flags); 2267 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 2268 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 2269 KASSERT((bp->b_flags & B_VMIO) != 0 || (bp->b_flags & B_NOREUSE) == 0, 2270 ("brelse: non-VMIO buffer marked NOREUSE")); 2271 2272 if (BUF_LOCKRECURSED(bp)) { 2273 /* 2274 * Do not process, in particular, do not handle the 2275 * B_INVAL/B_RELBUF and do not release to free list. 2276 */ 2277 BUF_UNLOCK(bp); 2278 return; 2279 } 2280 2281 if (bp->b_flags & B_MANAGED) { 2282 bqrelse(bp); 2283 return; 2284 } 2285 2286 if ((bp->b_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) { 2287 BO_LOCK(bp->b_bufobj); 2288 bp->b_vflags &= ~BV_BKGRDERR; 2289 BO_UNLOCK(bp->b_bufobj); 2290 bdirty(bp); 2291 } 2292 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 2293 !(bp->b_flags & B_INVAL)) { 2294 /* 2295 * Failed write, redirty. Must clear BIO_ERROR to prevent 2296 * pages from being scrapped. 2297 */ 2298 bp->b_ioflags &= ~BIO_ERROR; 2299 bdirty(bp); 2300 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 2301 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 2302 /* 2303 * Either a failed read I/O or we were asked to free or not 2304 * cache the buffer. 2305 */ 2306 bp->b_flags |= B_INVAL; 2307 if (!LIST_EMPTY(&bp->b_dep)) 2308 buf_deallocate(bp); 2309 if (bp->b_flags & B_DELWRI) 2310 bdirtysub(); 2311 bp->b_flags &= ~(B_DELWRI | B_CACHE); 2312 if ((bp->b_flags & B_VMIO) == 0) { 2313 allocbuf(bp, 0); 2314 if (bp->b_vp) 2315 brelvp(bp); 2316 } 2317 } 2318 2319 /* 2320 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_truncate() 2321 * is called with B_DELWRI set, the underlying pages may wind up 2322 * getting freed causing a previous write (bdwrite()) to get 'lost' 2323 * because pages associated with a B_DELWRI bp are marked clean. 2324 * 2325 * We still allow the B_INVAL case to call vfs_vmio_truncate(), even 2326 * if B_DELWRI is set. 2327 */ 2328 if (bp->b_flags & B_DELWRI) 2329 bp->b_flags &= ~B_RELBUF; 2330 2331 /* 2332 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 2333 * constituted, not even NFS buffers now. Two flags effect this. If 2334 * B_INVAL, the struct buf is invalidated but the VM object is kept 2335 * around ( i.e. so it is trivial to reconstitute the buffer later ). 2336 * 2337 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 2338 * invalidated. BIO_ERROR cannot be set for a failed write unless the 2339 * buffer is also B_INVAL because it hits the re-dirtying code above. 2340 * 2341 * Normally we can do this whether a buffer is B_DELWRI or not. If 2342 * the buffer is an NFS buffer, it is tracking piecemeal writes or 2343 * the commit state and we cannot afford to lose the buffer. If the 2344 * buffer has a background write in progress, we need to keep it 2345 * around to prevent it from being reconstituted and starting a second 2346 * background write. 2347 */ 2348 if ((bp->b_flags & B_VMIO) && (bp->b_flags & B_NOCACHE || 2349 (bp->b_ioflags & BIO_ERROR && bp->b_iocmd == BIO_READ)) && 2350 !(bp->b_vp->v_mount != NULL && 2351 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 2352 !vn_isdisk(bp->b_vp, NULL) && (bp->b_flags & B_DELWRI))) { 2353 vfs_vmio_invalidate(bp); 2354 allocbuf(bp, 0); 2355 } 2356 2357 if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0 || 2358 (bp->b_flags & (B_DELWRI | B_NOREUSE)) == B_NOREUSE) { 2359 allocbuf(bp, 0); 2360 bp->b_flags &= ~B_NOREUSE; 2361 if (bp->b_vp != NULL) 2362 brelvp(bp); 2363 } 2364 2365 /* 2366 * If the buffer has junk contents signal it and eventually 2367 * clean up B_DELWRI and diassociate the vnode so that gbincore() 2368 * doesn't find it. 2369 */ 2370 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 2371 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 2372 bp->b_flags |= B_INVAL; 2373 if (bp->b_flags & B_INVAL) { 2374 if (bp->b_flags & B_DELWRI) 2375 bundirty(bp); 2376 if (bp->b_vp) 2377 brelvp(bp); 2378 } 2379 2380 buf_track(bp, __func__); 2381 2382 /* buffers with no memory */ 2383 if (bp->b_bufsize == 0) { 2384 buf_free(bp); 2385 return; 2386 } 2387 /* buffers with junk contents */ 2388 if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 2389 (bp->b_ioflags & BIO_ERROR)) { 2390 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 2391 if (bp->b_vflags & BV_BKGRDINPROG) 2392 panic("losing buffer 2"); 2393 qindex = QUEUE_CLEAN; 2394 bp->b_flags |= B_AGE; 2395 /* remaining buffers */ 2396 } else if (bp->b_flags & B_DELWRI) 2397 qindex = QUEUE_DIRTY; 2398 else 2399 qindex = QUEUE_CLEAN; 2400 2401 binsfree(bp, qindex); 2402 2403 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 2404 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 2405 panic("brelse: not dirty"); 2406 /* unlock */ 2407 BUF_UNLOCK(bp); 2408 if (qindex == QUEUE_CLEAN) 2409 bufspace_wakeup(); 2410 } 2411 2412 /* 2413 * Release a buffer back to the appropriate queue but do not try to free 2414 * it. The buffer is expected to be used again soon. 2415 * 2416 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 2417 * biodone() to requeue an async I/O on completion. It is also used when 2418 * known good buffers need to be requeued but we think we may need the data 2419 * again soon. 2420 * 2421 * XXX we should be able to leave the B_RELBUF hint set on completion. 2422 */ 2423 void 2424 bqrelse(struct buf *bp) 2425 { 2426 int qindex; 2427 2428 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2429 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 2430 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 2431 2432 qindex = QUEUE_NONE; 2433 if (BUF_LOCKRECURSED(bp)) { 2434 /* do not release to free list */ 2435 BUF_UNLOCK(bp); 2436 return; 2437 } 2438 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 2439 2440 if (bp->b_flags & B_MANAGED) { 2441 if (bp->b_flags & B_REMFREE) 2442 bremfreef(bp); 2443 goto out; 2444 } 2445 2446 /* buffers with stale but valid contents */ 2447 if ((bp->b_flags & B_DELWRI) != 0 || (bp->b_vflags & (BV_BKGRDINPROG | 2448 BV_BKGRDERR)) == BV_BKGRDERR) { 2449 BO_LOCK(bp->b_bufobj); 2450 bp->b_vflags &= ~BV_BKGRDERR; 2451 BO_UNLOCK(bp->b_bufobj); 2452 qindex = QUEUE_DIRTY; 2453 } else { 2454 if ((bp->b_flags & B_DELWRI) == 0 && 2455 (bp->b_xflags & BX_VNDIRTY)) 2456 panic("bqrelse: not dirty"); 2457 if ((bp->b_flags & B_NOREUSE) != 0) { 2458 brelse(bp); 2459 return; 2460 } 2461 qindex = QUEUE_CLEAN; 2462 } 2463 binsfree(bp, qindex); 2464 2465 out: 2466 buf_track(bp, __func__); 2467 /* unlock */ 2468 BUF_UNLOCK(bp); 2469 if (qindex == QUEUE_CLEAN) 2470 bufspace_wakeup(); 2471 } 2472 2473 /* 2474 * Complete I/O to a VMIO backed page. Validate the pages as appropriate, 2475 * restore bogus pages. 2476 */ 2477 static void 2478 vfs_vmio_iodone(struct buf *bp) 2479 { 2480 vm_ooffset_t foff; 2481 vm_page_t m; 2482 vm_object_t obj; 2483 struct vnode *vp; 2484 int bogus, i, iosize; 2485 2486 obj = bp->b_bufobj->bo_object; 2487 KASSERT(obj->paging_in_progress >= bp->b_npages, 2488 ("vfs_vmio_iodone: paging in progress(%d) < b_npages(%d)", 2489 obj->paging_in_progress, bp->b_npages)); 2490 2491 vp = bp->b_vp; 2492 KASSERT(vp->v_holdcnt > 0, 2493 ("vfs_vmio_iodone: vnode %p has zero hold count", vp)); 2494 KASSERT(vp->v_object != NULL, 2495 ("vfs_vmio_iodone: vnode %p has no vm_object", vp)); 2496 2497 foff = bp->b_offset; 2498 KASSERT(bp->b_offset != NOOFFSET, 2499 ("vfs_vmio_iodone: bp %p has no buffer offset", bp)); 2500 2501 bogus = 0; 2502 iosize = bp->b_bcount - bp->b_resid; 2503 VM_OBJECT_WLOCK(obj); 2504 for (i = 0; i < bp->b_npages; i++) { 2505 int resid; 2506 2507 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 2508 if (resid > iosize) 2509 resid = iosize; 2510 2511 /* 2512 * cleanup bogus pages, restoring the originals 2513 */ 2514 m = bp->b_pages[i]; 2515 if (m == bogus_page) { 2516 bogus = 1; 2517 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 2518 if (m == NULL) 2519 panic("biodone: page disappeared!"); 2520 bp->b_pages[i] = m; 2521 } else if ((bp->b_iocmd == BIO_READ) && resid > 0) { 2522 /* 2523 * In the write case, the valid and clean bits are 2524 * already changed correctly ( see bdwrite() ), so we 2525 * only need to do this here in the read case. 2526 */ 2527 KASSERT((m->dirty & vm_page_bits(foff & PAGE_MASK, 2528 resid)) == 0, ("vfs_vmio_iodone: page %p " 2529 "has unexpected dirty bits", m)); 2530 vfs_page_set_valid(bp, foff, m); 2531 } 2532 KASSERT(OFF_TO_IDX(foff) == m->pindex, 2533 ("vfs_vmio_iodone: foff(%jd)/pindex(%ju) mismatch", 2534 (intmax_t)foff, (uintmax_t)m->pindex)); 2535 2536 vm_page_sunbusy(m); 2537 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2538 iosize -= resid; 2539 } 2540 vm_object_pip_wakeupn(obj, bp->b_npages); 2541 VM_OBJECT_WUNLOCK(obj); 2542 if (bogus && buf_mapped(bp)) { 2543 BUF_CHECK_MAPPED(bp); 2544 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 2545 bp->b_pages, bp->b_npages); 2546 } 2547 } 2548 2549 /* 2550 * Unwire a page held by a buf and place it on the appropriate vm queue. 2551 */ 2552 static void 2553 vfs_vmio_unwire(struct buf *bp, vm_page_t m) 2554 { 2555 bool freed; 2556 2557 vm_page_lock(m); 2558 if (vm_page_unwire(m, PQ_NONE)) { 2559 /* 2560 * Determine if the page should be freed before adding 2561 * it to the inactive queue. 2562 */ 2563 if (m->valid == 0) { 2564 freed = !vm_page_busied(m); 2565 if (freed) 2566 vm_page_free(m); 2567 } else if ((bp->b_flags & B_DIRECT) != 0) 2568 freed = vm_page_try_to_free(m); 2569 else 2570 freed = false; 2571 if (!freed) { 2572 /* 2573 * If the page is unlikely to be reused, let the 2574 * VM know. Otherwise, maintain LRU page 2575 * ordering and put the page at the tail of the 2576 * inactive queue. 2577 */ 2578 if ((bp->b_flags & B_NOREUSE) != 0) 2579 vm_page_deactivate_noreuse(m); 2580 else 2581 vm_page_deactivate(m); 2582 } 2583 } 2584 vm_page_unlock(m); 2585 } 2586 2587 /* 2588 * Perform page invalidation when a buffer is released. The fully invalid 2589 * pages will be reclaimed later in vfs_vmio_truncate(). 2590 */ 2591 static void 2592 vfs_vmio_invalidate(struct buf *bp) 2593 { 2594 vm_object_t obj; 2595 vm_page_t m; 2596 int i, resid, poffset, presid; 2597 2598 if (buf_mapped(bp)) { 2599 BUF_CHECK_MAPPED(bp); 2600 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages); 2601 } else 2602 BUF_CHECK_UNMAPPED(bp); 2603 /* 2604 * Get the base offset and length of the buffer. Note that 2605 * in the VMIO case if the buffer block size is not 2606 * page-aligned then b_data pointer may not be page-aligned. 2607 * But our b_pages[] array *IS* page aligned. 2608 * 2609 * block sizes less then DEV_BSIZE (usually 512) are not 2610 * supported due to the page granularity bits (m->valid, 2611 * m->dirty, etc...). 2612 * 2613 * See man buf(9) for more information 2614 */ 2615 obj = bp->b_bufobj->bo_object; 2616 resid = bp->b_bufsize; 2617 poffset = bp->b_offset & PAGE_MASK; 2618 VM_OBJECT_WLOCK(obj); 2619 for (i = 0; i < bp->b_npages; i++) { 2620 m = bp->b_pages[i]; 2621 if (m == bogus_page) 2622 panic("vfs_vmio_invalidate: Unexpected bogus page."); 2623 bp->b_pages[i] = NULL; 2624 2625 presid = resid > (PAGE_SIZE - poffset) ? 2626 (PAGE_SIZE - poffset) : resid; 2627 KASSERT(presid >= 0, ("brelse: extra page")); 2628 while (vm_page_xbusied(m)) { 2629 vm_page_lock(m); 2630 VM_OBJECT_WUNLOCK(obj); 2631 vm_page_busy_sleep(m, "mbncsh", true); 2632 VM_OBJECT_WLOCK(obj); 2633 } 2634 if (pmap_page_wired_mappings(m) == 0) 2635 vm_page_set_invalid(m, poffset, presid); 2636 vfs_vmio_unwire(bp, m); 2637 resid -= presid; 2638 poffset = 0; 2639 } 2640 VM_OBJECT_WUNLOCK(obj); 2641 bp->b_npages = 0; 2642 } 2643 2644 /* 2645 * Page-granular truncation of an existing VMIO buffer. 2646 */ 2647 static void 2648 vfs_vmio_truncate(struct buf *bp, int desiredpages) 2649 { 2650 vm_object_t obj; 2651 vm_page_t m; 2652 int i; 2653 2654 if (bp->b_npages == desiredpages) 2655 return; 2656 2657 if (buf_mapped(bp)) { 2658 BUF_CHECK_MAPPED(bp); 2659 pmap_qremove((vm_offset_t)trunc_page((vm_offset_t)bp->b_data) + 2660 (desiredpages << PAGE_SHIFT), bp->b_npages - desiredpages); 2661 } else 2662 BUF_CHECK_UNMAPPED(bp); 2663 obj = bp->b_bufobj->bo_object; 2664 if (obj != NULL) 2665 VM_OBJECT_WLOCK(obj); 2666 for (i = desiredpages; i < bp->b_npages; i++) { 2667 m = bp->b_pages[i]; 2668 KASSERT(m != bogus_page, ("allocbuf: bogus page found")); 2669 bp->b_pages[i] = NULL; 2670 vfs_vmio_unwire(bp, m); 2671 } 2672 if (obj != NULL) 2673 VM_OBJECT_WUNLOCK(obj); 2674 bp->b_npages = desiredpages; 2675 } 2676 2677 /* 2678 * Byte granular extension of VMIO buffers. 2679 */ 2680 static void 2681 vfs_vmio_extend(struct buf *bp, int desiredpages, int size) 2682 { 2683 /* 2684 * We are growing the buffer, possibly in a 2685 * byte-granular fashion. 2686 */ 2687 vm_object_t obj; 2688 vm_offset_t toff; 2689 vm_offset_t tinc; 2690 vm_page_t m; 2691 2692 /* 2693 * Step 1, bring in the VM pages from the object, allocating 2694 * them if necessary. We must clear B_CACHE if these pages 2695 * are not valid for the range covered by the buffer. 2696 */ 2697 obj = bp->b_bufobj->bo_object; 2698 VM_OBJECT_WLOCK(obj); 2699 while (bp->b_npages < desiredpages) { 2700 /* 2701 * We must allocate system pages since blocking 2702 * here could interfere with paging I/O, no 2703 * matter which process we are. 2704 * 2705 * Only exclusive busy can be tested here. 2706 * Blocking on shared busy might lead to 2707 * deadlocks once allocbuf() is called after 2708 * pages are vfs_busy_pages(). 2709 */ 2710 m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) + bp->b_npages, 2711 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM | 2712 VM_ALLOC_WIRED | VM_ALLOC_IGN_SBUSY | 2713 VM_ALLOC_COUNT(desiredpages - bp->b_npages)); 2714 if (m->valid == 0) 2715 bp->b_flags &= ~B_CACHE; 2716 bp->b_pages[bp->b_npages] = m; 2717 ++bp->b_npages; 2718 } 2719 2720 /* 2721 * Step 2. We've loaded the pages into the buffer, 2722 * we have to figure out if we can still have B_CACHE 2723 * set. Note that B_CACHE is set according to the 2724 * byte-granular range ( bcount and size ), not the 2725 * aligned range ( newbsize ). 2726 * 2727 * The VM test is against m->valid, which is DEV_BSIZE 2728 * aligned. Needless to say, the validity of the data 2729 * needs to also be DEV_BSIZE aligned. Note that this 2730 * fails with NFS if the server or some other client 2731 * extends the file's EOF. If our buffer is resized, 2732 * B_CACHE may remain set! XXX 2733 */ 2734 toff = bp->b_bcount; 2735 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 2736 while ((bp->b_flags & B_CACHE) && toff < size) { 2737 vm_pindex_t pi; 2738 2739 if (tinc > (size - toff)) 2740 tinc = size - toff; 2741 pi = ((bp->b_offset & PAGE_MASK) + toff) >> PAGE_SHIFT; 2742 m = bp->b_pages[pi]; 2743 vfs_buf_test_cache(bp, bp->b_offset, toff, tinc, m); 2744 toff += tinc; 2745 tinc = PAGE_SIZE; 2746 } 2747 VM_OBJECT_WUNLOCK(obj); 2748 2749 /* 2750 * Step 3, fixup the KVA pmap. 2751 */ 2752 if (buf_mapped(bp)) 2753 bpmap_qenter(bp); 2754 else 2755 BUF_CHECK_UNMAPPED(bp); 2756 } 2757 2758 /* 2759 * Check to see if a block at a particular lbn is available for a clustered 2760 * write. 2761 */ 2762 static int 2763 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 2764 { 2765 struct buf *bpa; 2766 int match; 2767 2768 match = 0; 2769 2770 /* If the buf isn't in core skip it */ 2771 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 2772 return (0); 2773 2774 /* If the buf is busy we don't want to wait for it */ 2775 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2776 return (0); 2777 2778 /* Only cluster with valid clusterable delayed write buffers */ 2779 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 2780 (B_DELWRI | B_CLUSTEROK)) 2781 goto done; 2782 2783 if (bpa->b_bufsize != size) 2784 goto done; 2785 2786 /* 2787 * Check to see if it is in the expected place on disk and that the 2788 * block has been mapped. 2789 */ 2790 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 2791 match = 1; 2792 done: 2793 BUF_UNLOCK(bpa); 2794 return (match); 2795 } 2796 2797 /* 2798 * vfs_bio_awrite: 2799 * 2800 * Implement clustered async writes for clearing out B_DELWRI buffers. 2801 * This is much better then the old way of writing only one buffer at 2802 * a time. Note that we may not be presented with the buffers in the 2803 * correct order, so we search for the cluster in both directions. 2804 */ 2805 int 2806 vfs_bio_awrite(struct buf *bp) 2807 { 2808 struct bufobj *bo; 2809 int i; 2810 int j; 2811 daddr_t lblkno = bp->b_lblkno; 2812 struct vnode *vp = bp->b_vp; 2813 int ncl; 2814 int nwritten; 2815 int size; 2816 int maxcl; 2817 int gbflags; 2818 2819 bo = &vp->v_bufobj; 2820 gbflags = (bp->b_data == unmapped_buf) ? GB_UNMAPPED : 0; 2821 /* 2822 * right now we support clustered writing only to regular files. If 2823 * we find a clusterable block we could be in the middle of a cluster 2824 * rather then at the beginning. 2825 */ 2826 if ((vp->v_type == VREG) && 2827 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 2828 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 2829 2830 size = vp->v_mount->mnt_stat.f_iosize; 2831 maxcl = MAXPHYS / size; 2832 2833 BO_RLOCK(bo); 2834 for (i = 1; i < maxcl; i++) 2835 if (vfs_bio_clcheck(vp, size, lblkno + i, 2836 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 2837 break; 2838 2839 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 2840 if (vfs_bio_clcheck(vp, size, lblkno - j, 2841 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 2842 break; 2843 BO_RUNLOCK(bo); 2844 --j; 2845 ncl = i + j; 2846 /* 2847 * this is a possible cluster write 2848 */ 2849 if (ncl != 1) { 2850 BUF_UNLOCK(bp); 2851 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl, 2852 gbflags); 2853 return (nwritten); 2854 } 2855 } 2856 bremfree(bp); 2857 bp->b_flags |= B_ASYNC; 2858 /* 2859 * default (old) behavior, writing out only one block 2860 * 2861 * XXX returns b_bufsize instead of b_bcount for nwritten? 2862 */ 2863 nwritten = bp->b_bufsize; 2864 (void) bwrite(bp); 2865 2866 return (nwritten); 2867 } 2868 2869 /* 2870 * getnewbuf_kva: 2871 * 2872 * Allocate KVA for an empty buf header according to gbflags. 2873 */ 2874 static int 2875 getnewbuf_kva(struct buf *bp, int gbflags, int maxsize) 2876 { 2877 2878 if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_UNMAPPED) { 2879 /* 2880 * In order to keep fragmentation sane we only allocate kva 2881 * in BKVASIZE chunks. XXX with vmem we can do page size. 2882 */ 2883 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2884 2885 if (maxsize != bp->b_kvasize && 2886 bufkva_alloc(bp, maxsize, gbflags)) 2887 return (ENOSPC); 2888 } 2889 return (0); 2890 } 2891 2892 /* 2893 * getnewbuf: 2894 * 2895 * Find and initialize a new buffer header, freeing up existing buffers 2896 * in the bufqueues as necessary. The new buffer is returned locked. 2897 * 2898 * We block if: 2899 * We have insufficient buffer headers 2900 * We have insufficient buffer space 2901 * buffer_arena is too fragmented ( space reservation fails ) 2902 * If we have to flush dirty buffers ( but we try to avoid this ) 2903 * 2904 * The caller is responsible for releasing the reserved bufspace after 2905 * allocbuf() is called. 2906 */ 2907 static struct buf * 2908 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int maxsize, int gbflags) 2909 { 2910 struct buf *bp; 2911 bool metadata, reserved; 2912 2913 bp = NULL; 2914 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 2915 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 2916 if (!unmapped_buf_allowed) 2917 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC); 2918 2919 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 || 2920 vp->v_type == VCHR) 2921 metadata = true; 2922 else 2923 metadata = false; 2924 atomic_add_int(&getnewbufcalls, 1); 2925 reserved = false; 2926 do { 2927 if (reserved == false && 2928 bufspace_reserve(maxsize, metadata) != 0) 2929 continue; 2930 reserved = true; 2931 if ((bp = buf_alloc()) == NULL) 2932 continue; 2933 if (getnewbuf_kva(bp, gbflags, maxsize) == 0) 2934 return (bp); 2935 break; 2936 } while(buf_scan(false) == 0); 2937 2938 if (reserved) 2939 atomic_subtract_long(&bufspace, maxsize); 2940 if (bp != NULL) { 2941 bp->b_flags |= B_INVAL; 2942 brelse(bp); 2943 } 2944 bufspace_wait(vp, gbflags, slpflag, slptimeo); 2945 2946 return (NULL); 2947 } 2948 2949 /* 2950 * buf_daemon: 2951 * 2952 * buffer flushing daemon. Buffers are normally flushed by the 2953 * update daemon but if it cannot keep up this process starts to 2954 * take the load in an attempt to prevent getnewbuf() from blocking. 2955 */ 2956 static struct kproc_desc buf_kp = { 2957 "bufdaemon", 2958 buf_daemon, 2959 &bufdaemonproc 2960 }; 2961 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 2962 2963 static int 2964 buf_flush(struct vnode *vp, int target) 2965 { 2966 int flushed; 2967 2968 flushed = flushbufqueues(vp, target, 0); 2969 if (flushed == 0) { 2970 /* 2971 * Could not find any buffers without rollback 2972 * dependencies, so just write the first one 2973 * in the hopes of eventually making progress. 2974 */ 2975 if (vp != NULL && target > 2) 2976 target /= 2; 2977 flushbufqueues(vp, target, 1); 2978 } 2979 return (flushed); 2980 } 2981 2982 static void 2983 buf_daemon() 2984 { 2985 int lodirty; 2986 2987 /* 2988 * This process needs to be suspended prior to shutdown sync. 2989 */ 2990 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2991 SHUTDOWN_PRI_LAST); 2992 2993 /* 2994 * This process is allowed to take the buffer cache to the limit 2995 */ 2996 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 2997 mtx_lock(&bdlock); 2998 for (;;) { 2999 bd_request = 0; 3000 mtx_unlock(&bdlock); 3001 3002 kproc_suspend_check(bufdaemonproc); 3003 lodirty = lodirtybuffers; 3004 if (bd_speedupreq) { 3005 lodirty = numdirtybuffers / 2; 3006 bd_speedupreq = 0; 3007 } 3008 /* 3009 * Do the flush. Limit the amount of in-transit I/O we 3010 * allow to build up, otherwise we would completely saturate 3011 * the I/O system. 3012 */ 3013 while (numdirtybuffers > lodirty) { 3014 if (buf_flush(NULL, numdirtybuffers - lodirty) == 0) 3015 break; 3016 kern_yield(PRI_USER); 3017 } 3018 3019 /* 3020 * Only clear bd_request if we have reached our low water 3021 * mark. The buf_daemon normally waits 1 second and 3022 * then incrementally flushes any dirty buffers that have 3023 * built up, within reason. 3024 * 3025 * If we were unable to hit our low water mark and couldn't 3026 * find any flushable buffers, we sleep for a short period 3027 * to avoid endless loops on unlockable buffers. 3028 */ 3029 mtx_lock(&bdlock); 3030 if (numdirtybuffers <= lodirtybuffers) { 3031 /* 3032 * We reached our low water mark, reset the 3033 * request and sleep until we are needed again. 3034 * The sleep is just so the suspend code works. 3035 */ 3036 bd_request = 0; 3037 /* 3038 * Do an extra wakeup in case dirty threshold 3039 * changed via sysctl and the explicit transition 3040 * out of shortfall was missed. 3041 */ 3042 bdirtywakeup(); 3043 if (runningbufspace <= lorunningspace) 3044 runningwakeup(); 3045 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 3046 } else { 3047 /* 3048 * We couldn't find any flushable dirty buffers but 3049 * still have too many dirty buffers, we 3050 * have to sleep and try again. (rare) 3051 */ 3052 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 3053 } 3054 } 3055 } 3056 3057 /* 3058 * flushbufqueues: 3059 * 3060 * Try to flush a buffer in the dirty queue. We must be careful to 3061 * free up B_INVAL buffers instead of write them, which NFS is 3062 * particularly sensitive to. 3063 */ 3064 static int flushwithdeps = 0; 3065 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 3066 0, "Number of buffers flushed with dependecies that require rollbacks"); 3067 3068 static int 3069 flushbufqueues(struct vnode *lvp, int target, int flushdeps) 3070 { 3071 struct buf *sentinel; 3072 struct vnode *vp; 3073 struct mount *mp; 3074 struct buf *bp; 3075 int hasdeps; 3076 int flushed; 3077 int queue; 3078 int error; 3079 bool unlock; 3080 3081 flushed = 0; 3082 queue = QUEUE_DIRTY; 3083 bp = NULL; 3084 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 3085 sentinel->b_qindex = QUEUE_SENTINEL; 3086 mtx_lock(&bqlocks[queue]); 3087 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist); 3088 mtx_unlock(&bqlocks[queue]); 3089 while (flushed != target) { 3090 maybe_yield(); 3091 mtx_lock(&bqlocks[queue]); 3092 bp = TAILQ_NEXT(sentinel, b_freelist); 3093 if (bp != NULL) { 3094 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 3095 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel, 3096 b_freelist); 3097 } else { 3098 mtx_unlock(&bqlocks[queue]); 3099 break; 3100 } 3101 /* 3102 * Skip sentinels inserted by other invocations of the 3103 * flushbufqueues(), taking care to not reorder them. 3104 * 3105 * Only flush the buffers that belong to the 3106 * vnode locked by the curthread. 3107 */ 3108 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL && 3109 bp->b_vp != lvp)) { 3110 mtx_unlock(&bqlocks[queue]); 3111 continue; 3112 } 3113 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL); 3114 mtx_unlock(&bqlocks[queue]); 3115 if (error != 0) 3116 continue; 3117 3118 /* 3119 * BKGRDINPROG can only be set with the buf and bufobj 3120 * locks both held. We tolerate a race to clear it here. 3121 */ 3122 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 3123 (bp->b_flags & B_DELWRI) == 0) { 3124 BUF_UNLOCK(bp); 3125 continue; 3126 } 3127 if (bp->b_flags & B_INVAL) { 3128 bremfreef(bp); 3129 brelse(bp); 3130 flushed++; 3131 continue; 3132 } 3133 3134 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 3135 if (flushdeps == 0) { 3136 BUF_UNLOCK(bp); 3137 continue; 3138 } 3139 hasdeps = 1; 3140 } else 3141 hasdeps = 0; 3142 /* 3143 * We must hold the lock on a vnode before writing 3144 * one of its buffers. Otherwise we may confuse, or 3145 * in the case of a snapshot vnode, deadlock the 3146 * system. 3147 * 3148 * The lock order here is the reverse of the normal 3149 * of vnode followed by buf lock. This is ok because 3150 * the NOWAIT will prevent deadlock. 3151 */ 3152 vp = bp->b_vp; 3153 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 3154 BUF_UNLOCK(bp); 3155 continue; 3156 } 3157 if (lvp == NULL) { 3158 unlock = true; 3159 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT); 3160 } else { 3161 ASSERT_VOP_LOCKED(vp, "getbuf"); 3162 unlock = false; 3163 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 : 3164 vn_lock(vp, LK_TRYUPGRADE); 3165 } 3166 if (error == 0) { 3167 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 3168 bp, bp->b_vp, bp->b_flags); 3169 if (curproc == bufdaemonproc) { 3170 vfs_bio_awrite(bp); 3171 } else { 3172 bremfree(bp); 3173 bwrite(bp); 3174 notbufdflushes++; 3175 } 3176 vn_finished_write(mp); 3177 if (unlock) 3178 VOP_UNLOCK(vp, 0); 3179 flushwithdeps += hasdeps; 3180 flushed++; 3181 3182 /* 3183 * Sleeping on runningbufspace while holding 3184 * vnode lock leads to deadlock. 3185 */ 3186 if (curproc == bufdaemonproc && 3187 runningbufspace > hirunningspace) 3188 waitrunningbufspace(); 3189 continue; 3190 } 3191 vn_finished_write(mp); 3192 BUF_UNLOCK(bp); 3193 } 3194 mtx_lock(&bqlocks[queue]); 3195 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 3196 mtx_unlock(&bqlocks[queue]); 3197 free(sentinel, M_TEMP); 3198 return (flushed); 3199 } 3200 3201 /* 3202 * Check to see if a block is currently memory resident. 3203 */ 3204 struct buf * 3205 incore(struct bufobj *bo, daddr_t blkno) 3206 { 3207 struct buf *bp; 3208 3209 BO_RLOCK(bo); 3210 bp = gbincore(bo, blkno); 3211 BO_RUNLOCK(bo); 3212 return (bp); 3213 } 3214 3215 /* 3216 * Returns true if no I/O is needed to access the 3217 * associated VM object. This is like incore except 3218 * it also hunts around in the VM system for the data. 3219 */ 3220 3221 static int 3222 inmem(struct vnode * vp, daddr_t blkno) 3223 { 3224 vm_object_t obj; 3225 vm_offset_t toff, tinc, size; 3226 vm_page_t m; 3227 vm_ooffset_t off; 3228 3229 ASSERT_VOP_LOCKED(vp, "inmem"); 3230 3231 if (incore(&vp->v_bufobj, blkno)) 3232 return 1; 3233 if (vp->v_mount == NULL) 3234 return 0; 3235 obj = vp->v_object; 3236 if (obj == NULL) 3237 return (0); 3238 3239 size = PAGE_SIZE; 3240 if (size > vp->v_mount->mnt_stat.f_iosize) 3241 size = vp->v_mount->mnt_stat.f_iosize; 3242 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 3243 3244 VM_OBJECT_RLOCK(obj); 3245 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 3246 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 3247 if (!m) 3248 goto notinmem; 3249 tinc = size; 3250 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 3251 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 3252 if (vm_page_is_valid(m, 3253 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 3254 goto notinmem; 3255 } 3256 VM_OBJECT_RUNLOCK(obj); 3257 return 1; 3258 3259 notinmem: 3260 VM_OBJECT_RUNLOCK(obj); 3261 return (0); 3262 } 3263 3264 /* 3265 * Set the dirty range for a buffer based on the status of the dirty 3266 * bits in the pages comprising the buffer. The range is limited 3267 * to the size of the buffer. 3268 * 3269 * Tell the VM system that the pages associated with this buffer 3270 * are clean. This is used for delayed writes where the data is 3271 * going to go to disk eventually without additional VM intevention. 3272 * 3273 * Note that while we only really need to clean through to b_bcount, we 3274 * just go ahead and clean through to b_bufsize. 3275 */ 3276 static void 3277 vfs_clean_pages_dirty_buf(struct buf *bp) 3278 { 3279 vm_ooffset_t foff, noff, eoff; 3280 vm_page_t m; 3281 int i; 3282 3283 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 3284 return; 3285 3286 foff = bp->b_offset; 3287 KASSERT(bp->b_offset != NOOFFSET, 3288 ("vfs_clean_pages_dirty_buf: no buffer offset")); 3289 3290 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 3291 vfs_drain_busy_pages(bp); 3292 vfs_setdirty_locked_object(bp); 3293 for (i = 0; i < bp->b_npages; i++) { 3294 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3295 eoff = noff; 3296 if (eoff > bp->b_offset + bp->b_bufsize) 3297 eoff = bp->b_offset + bp->b_bufsize; 3298 m = bp->b_pages[i]; 3299 vfs_page_set_validclean(bp, foff, m); 3300 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3301 foff = noff; 3302 } 3303 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 3304 } 3305 3306 static void 3307 vfs_setdirty_locked_object(struct buf *bp) 3308 { 3309 vm_object_t object; 3310 int i; 3311 3312 object = bp->b_bufobj->bo_object; 3313 VM_OBJECT_ASSERT_WLOCKED(object); 3314 3315 /* 3316 * We qualify the scan for modified pages on whether the 3317 * object has been flushed yet. 3318 */ 3319 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) { 3320 vm_offset_t boffset; 3321 vm_offset_t eoffset; 3322 3323 /* 3324 * test the pages to see if they have been modified directly 3325 * by users through the VM system. 3326 */ 3327 for (i = 0; i < bp->b_npages; i++) 3328 vm_page_test_dirty(bp->b_pages[i]); 3329 3330 /* 3331 * Calculate the encompassing dirty range, boffset and eoffset, 3332 * (eoffset - boffset) bytes. 3333 */ 3334 3335 for (i = 0; i < bp->b_npages; i++) { 3336 if (bp->b_pages[i]->dirty) 3337 break; 3338 } 3339 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3340 3341 for (i = bp->b_npages - 1; i >= 0; --i) { 3342 if (bp->b_pages[i]->dirty) { 3343 break; 3344 } 3345 } 3346 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3347 3348 /* 3349 * Fit it to the buffer. 3350 */ 3351 3352 if (eoffset > bp->b_bcount) 3353 eoffset = bp->b_bcount; 3354 3355 /* 3356 * If we have a good dirty range, merge with the existing 3357 * dirty range. 3358 */ 3359 3360 if (boffset < eoffset) { 3361 if (bp->b_dirtyoff > boffset) 3362 bp->b_dirtyoff = boffset; 3363 if (bp->b_dirtyend < eoffset) 3364 bp->b_dirtyend = eoffset; 3365 } 3366 } 3367 } 3368 3369 /* 3370 * Allocate the KVA mapping for an existing buffer. 3371 * If an unmapped buffer is provided but a mapped buffer is requested, take 3372 * also care to properly setup mappings between pages and KVA. 3373 */ 3374 static void 3375 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags) 3376 { 3377 int bsize, maxsize, need_mapping, need_kva; 3378 off_t offset; 3379 3380 need_mapping = bp->b_data == unmapped_buf && 3381 (gbflags & GB_UNMAPPED) == 0; 3382 need_kva = bp->b_kvabase == unmapped_buf && 3383 bp->b_data == unmapped_buf && 3384 (gbflags & GB_KVAALLOC) != 0; 3385 if (!need_mapping && !need_kva) 3386 return; 3387 3388 BUF_CHECK_UNMAPPED(bp); 3389 3390 if (need_mapping && bp->b_kvabase != unmapped_buf) { 3391 /* 3392 * Buffer is not mapped, but the KVA was already 3393 * reserved at the time of the instantiation. Use the 3394 * allocated space. 3395 */ 3396 goto has_addr; 3397 } 3398 3399 /* 3400 * Calculate the amount of the address space we would reserve 3401 * if the buffer was mapped. 3402 */ 3403 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize; 3404 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3405 offset = blkno * bsize; 3406 maxsize = size + (offset & PAGE_MASK); 3407 maxsize = imax(maxsize, bsize); 3408 3409 while (bufkva_alloc(bp, maxsize, gbflags) != 0) { 3410 if ((gbflags & GB_NOWAIT_BD) != 0) { 3411 /* 3412 * XXXKIB: defragmentation cannot 3413 * succeed, not sure what else to do. 3414 */ 3415 panic("GB_NOWAIT_BD and GB_UNMAPPED %p", bp); 3416 } 3417 atomic_add_int(&mappingrestarts, 1); 3418 bufspace_wait(bp->b_vp, gbflags, 0, 0); 3419 } 3420 has_addr: 3421 if (need_mapping) { 3422 /* b_offset is handled by bpmap_qenter. */ 3423 bp->b_data = bp->b_kvabase; 3424 BUF_CHECK_MAPPED(bp); 3425 bpmap_qenter(bp); 3426 } 3427 } 3428 3429 /* 3430 * getblk: 3431 * 3432 * Get a block given a specified block and offset into a file/device. 3433 * The buffers B_DONE bit will be cleared on return, making it almost 3434 * ready for an I/O initiation. B_INVAL may or may not be set on 3435 * return. The caller should clear B_INVAL prior to initiating a 3436 * READ. 3437 * 3438 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 3439 * an existing buffer. 3440 * 3441 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 3442 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 3443 * and then cleared based on the backing VM. If the previous buffer is 3444 * non-0-sized but invalid, B_CACHE will be cleared. 3445 * 3446 * If getblk() must create a new buffer, the new buffer is returned with 3447 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 3448 * case it is returned with B_INVAL clear and B_CACHE set based on the 3449 * backing VM. 3450 * 3451 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 3452 * B_CACHE bit is clear. 3453 * 3454 * What this means, basically, is that the caller should use B_CACHE to 3455 * determine whether the buffer is fully valid or not and should clear 3456 * B_INVAL prior to issuing a read. If the caller intends to validate 3457 * the buffer by loading its data area with something, the caller needs 3458 * to clear B_INVAL. If the caller does this without issuing an I/O, 3459 * the caller should set B_CACHE ( as an optimization ), else the caller 3460 * should issue the I/O and biodone() will set B_CACHE if the I/O was 3461 * a write attempt or if it was a successful read. If the caller 3462 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 3463 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 3464 */ 3465 struct buf * 3466 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3467 int flags) 3468 { 3469 struct buf *bp; 3470 struct bufobj *bo; 3471 int bsize, error, maxsize, vmio; 3472 off_t offset; 3473 3474 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 3475 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3476 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3477 ASSERT_VOP_LOCKED(vp, "getblk"); 3478 if (size > MAXBCACHEBUF) 3479 panic("getblk: size(%d) > MAXBCACHEBUF(%d)\n", size, 3480 MAXBCACHEBUF); 3481 if (!unmapped_buf_allowed) 3482 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3483 3484 bo = &vp->v_bufobj; 3485 loop: 3486 BO_RLOCK(bo); 3487 bp = gbincore(bo, blkno); 3488 if (bp != NULL) { 3489 int lockflags; 3490 /* 3491 * Buffer is in-core. If the buffer is not busy nor managed, 3492 * it must be on a queue. 3493 */ 3494 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 3495 3496 if (flags & GB_LOCK_NOWAIT) 3497 lockflags |= LK_NOWAIT; 3498 3499 error = BUF_TIMELOCK(bp, lockflags, 3500 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo); 3501 3502 /* 3503 * If we slept and got the lock we have to restart in case 3504 * the buffer changed identities. 3505 */ 3506 if (error == ENOLCK) 3507 goto loop; 3508 /* We timed out or were interrupted. */ 3509 else if (error) 3510 return (NULL); 3511 /* If recursed, assume caller knows the rules. */ 3512 else if (BUF_LOCKRECURSED(bp)) 3513 goto end; 3514 3515 /* 3516 * The buffer is locked. B_CACHE is cleared if the buffer is 3517 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 3518 * and for a VMIO buffer B_CACHE is adjusted according to the 3519 * backing VM cache. 3520 */ 3521 if (bp->b_flags & B_INVAL) 3522 bp->b_flags &= ~B_CACHE; 3523 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 3524 bp->b_flags |= B_CACHE; 3525 if (bp->b_flags & B_MANAGED) 3526 MPASS(bp->b_qindex == QUEUE_NONE); 3527 else 3528 bremfree(bp); 3529 3530 /* 3531 * check for size inconsistencies for non-VMIO case. 3532 */ 3533 if (bp->b_bcount != size) { 3534 if ((bp->b_flags & B_VMIO) == 0 || 3535 (size > bp->b_kvasize)) { 3536 if (bp->b_flags & B_DELWRI) { 3537 bp->b_flags |= B_NOCACHE; 3538 bwrite(bp); 3539 } else { 3540 if (LIST_EMPTY(&bp->b_dep)) { 3541 bp->b_flags |= B_RELBUF; 3542 brelse(bp); 3543 } else { 3544 bp->b_flags |= B_NOCACHE; 3545 bwrite(bp); 3546 } 3547 } 3548 goto loop; 3549 } 3550 } 3551 3552 /* 3553 * Handle the case of unmapped buffer which should 3554 * become mapped, or the buffer for which KVA 3555 * reservation is requested. 3556 */ 3557 bp_unmapped_get_kva(bp, blkno, size, flags); 3558 3559 /* 3560 * If the size is inconsistent in the VMIO case, we can resize 3561 * the buffer. This might lead to B_CACHE getting set or 3562 * cleared. If the size has not changed, B_CACHE remains 3563 * unchanged from its previous state. 3564 */ 3565 allocbuf(bp, size); 3566 3567 KASSERT(bp->b_offset != NOOFFSET, 3568 ("getblk: no buffer offset")); 3569 3570 /* 3571 * A buffer with B_DELWRI set and B_CACHE clear must 3572 * be committed before we can return the buffer in 3573 * order to prevent the caller from issuing a read 3574 * ( due to B_CACHE not being set ) and overwriting 3575 * it. 3576 * 3577 * Most callers, including NFS and FFS, need this to 3578 * operate properly either because they assume they 3579 * can issue a read if B_CACHE is not set, or because 3580 * ( for example ) an uncached B_DELWRI might loop due 3581 * to softupdates re-dirtying the buffer. In the latter 3582 * case, B_CACHE is set after the first write completes, 3583 * preventing further loops. 3584 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 3585 * above while extending the buffer, we cannot allow the 3586 * buffer to remain with B_CACHE set after the write 3587 * completes or it will represent a corrupt state. To 3588 * deal with this we set B_NOCACHE to scrap the buffer 3589 * after the write. 3590 * 3591 * We might be able to do something fancy, like setting 3592 * B_CACHE in bwrite() except if B_DELWRI is already set, 3593 * so the below call doesn't set B_CACHE, but that gets real 3594 * confusing. This is much easier. 3595 */ 3596 3597 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 3598 bp->b_flags |= B_NOCACHE; 3599 bwrite(bp); 3600 goto loop; 3601 } 3602 bp->b_flags &= ~B_DONE; 3603 } else { 3604 /* 3605 * Buffer is not in-core, create new buffer. The buffer 3606 * returned by getnewbuf() is locked. Note that the returned 3607 * buffer is also considered valid (not marked B_INVAL). 3608 */ 3609 BO_RUNLOCK(bo); 3610 /* 3611 * If the user does not want us to create the buffer, bail out 3612 * here. 3613 */ 3614 if (flags & GB_NOCREAT) 3615 return NULL; 3616 if (numfreebuffers == 0 && TD_IS_IDLETHREAD(curthread)) 3617 return NULL; 3618 3619 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize; 3620 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3621 offset = blkno * bsize; 3622 vmio = vp->v_object != NULL; 3623 if (vmio) { 3624 maxsize = size + (offset & PAGE_MASK); 3625 } else { 3626 maxsize = size; 3627 /* Do not allow non-VMIO notmapped buffers. */ 3628 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3629 } 3630 maxsize = imax(maxsize, bsize); 3631 3632 bp = getnewbuf(vp, slpflag, slptimeo, maxsize, flags); 3633 if (bp == NULL) { 3634 if (slpflag || slptimeo) 3635 return NULL; 3636 /* 3637 * XXX This is here until the sleep path is diagnosed 3638 * enough to work under very low memory conditions. 3639 * 3640 * There's an issue on low memory, 4BSD+non-preempt 3641 * systems (eg MIPS routers with 32MB RAM) where buffer 3642 * exhaustion occurs without sleeping for buffer 3643 * reclaimation. This just sticks in a loop and 3644 * constantly attempts to allocate a buffer, which 3645 * hits exhaustion and tries to wakeup bufdaemon. 3646 * This never happens because we never yield. 3647 * 3648 * The real solution is to identify and fix these cases 3649 * so we aren't effectively busy-waiting in a loop 3650 * until the reclaimation path has cycles to run. 3651 */ 3652 kern_yield(PRI_USER); 3653 goto loop; 3654 } 3655 3656 /* 3657 * This code is used to make sure that a buffer is not 3658 * created while the getnewbuf routine is blocked. 3659 * This can be a problem whether the vnode is locked or not. 3660 * If the buffer is created out from under us, we have to 3661 * throw away the one we just created. 3662 * 3663 * Note: this must occur before we associate the buffer 3664 * with the vp especially considering limitations in 3665 * the splay tree implementation when dealing with duplicate 3666 * lblkno's. 3667 */ 3668 BO_LOCK(bo); 3669 if (gbincore(bo, blkno)) { 3670 BO_UNLOCK(bo); 3671 bp->b_flags |= B_INVAL; 3672 brelse(bp); 3673 bufspace_release(maxsize); 3674 goto loop; 3675 } 3676 3677 /* 3678 * Insert the buffer into the hash, so that it can 3679 * be found by incore. 3680 */ 3681 bp->b_blkno = bp->b_lblkno = blkno; 3682 bp->b_offset = offset; 3683 bgetvp(vp, bp); 3684 BO_UNLOCK(bo); 3685 3686 /* 3687 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 3688 * buffer size starts out as 0, B_CACHE will be set by 3689 * allocbuf() for the VMIO case prior to it testing the 3690 * backing store for validity. 3691 */ 3692 3693 if (vmio) { 3694 bp->b_flags |= B_VMIO; 3695 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 3696 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 3697 bp, vp->v_object, bp->b_bufobj->bo_object)); 3698 } else { 3699 bp->b_flags &= ~B_VMIO; 3700 KASSERT(bp->b_bufobj->bo_object == NULL, 3701 ("ARGH! has b_bufobj->bo_object %p %p\n", 3702 bp, bp->b_bufobj->bo_object)); 3703 BUF_CHECK_MAPPED(bp); 3704 } 3705 3706 allocbuf(bp, size); 3707 bufspace_release(maxsize); 3708 bp->b_flags &= ~B_DONE; 3709 } 3710 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 3711 BUF_ASSERT_HELD(bp); 3712 end: 3713 buf_track(bp, __func__); 3714 KASSERT(bp->b_bufobj == bo, 3715 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 3716 return (bp); 3717 } 3718 3719 /* 3720 * Get an empty, disassociated buffer of given size. The buffer is initially 3721 * set to B_INVAL. 3722 */ 3723 struct buf * 3724 geteblk(int size, int flags) 3725 { 3726 struct buf *bp; 3727 int maxsize; 3728 3729 maxsize = (size + BKVAMASK) & ~BKVAMASK; 3730 while ((bp = getnewbuf(NULL, 0, 0, maxsize, flags)) == NULL) { 3731 if ((flags & GB_NOWAIT_BD) && 3732 (curthread->td_pflags & TDP_BUFNEED) != 0) 3733 return (NULL); 3734 } 3735 allocbuf(bp, size); 3736 bufspace_release(maxsize); 3737 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 3738 BUF_ASSERT_HELD(bp); 3739 return (bp); 3740 } 3741 3742 /* 3743 * Truncate the backing store for a non-vmio buffer. 3744 */ 3745 static void 3746 vfs_nonvmio_truncate(struct buf *bp, int newbsize) 3747 { 3748 3749 if (bp->b_flags & B_MALLOC) { 3750 /* 3751 * malloced buffers are not shrunk 3752 */ 3753 if (newbsize == 0) { 3754 bufmallocadjust(bp, 0); 3755 free(bp->b_data, M_BIOBUF); 3756 bp->b_data = bp->b_kvabase; 3757 bp->b_flags &= ~B_MALLOC; 3758 } 3759 return; 3760 } 3761 vm_hold_free_pages(bp, newbsize); 3762 bufspace_adjust(bp, newbsize); 3763 } 3764 3765 /* 3766 * Extend the backing for a non-VMIO buffer. 3767 */ 3768 static void 3769 vfs_nonvmio_extend(struct buf *bp, int newbsize) 3770 { 3771 caddr_t origbuf; 3772 int origbufsize; 3773 3774 /* 3775 * We only use malloced memory on the first allocation. 3776 * and revert to page-allocated memory when the buffer 3777 * grows. 3778 * 3779 * There is a potential smp race here that could lead 3780 * to bufmallocspace slightly passing the max. It 3781 * is probably extremely rare and not worth worrying 3782 * over. 3783 */ 3784 if (bp->b_bufsize == 0 && newbsize <= PAGE_SIZE/2 && 3785 bufmallocspace < maxbufmallocspace) { 3786 bp->b_data = malloc(newbsize, M_BIOBUF, M_WAITOK); 3787 bp->b_flags |= B_MALLOC; 3788 bufmallocadjust(bp, newbsize); 3789 return; 3790 } 3791 3792 /* 3793 * If the buffer is growing on its other-than-first 3794 * allocation then we revert to the page-allocation 3795 * scheme. 3796 */ 3797 origbuf = NULL; 3798 origbufsize = 0; 3799 if (bp->b_flags & B_MALLOC) { 3800 origbuf = bp->b_data; 3801 origbufsize = bp->b_bufsize; 3802 bp->b_data = bp->b_kvabase; 3803 bufmallocadjust(bp, 0); 3804 bp->b_flags &= ~B_MALLOC; 3805 newbsize = round_page(newbsize); 3806 } 3807 vm_hold_load_pages(bp, (vm_offset_t) bp->b_data + bp->b_bufsize, 3808 (vm_offset_t) bp->b_data + newbsize); 3809 if (origbuf != NULL) { 3810 bcopy(origbuf, bp->b_data, origbufsize); 3811 free(origbuf, M_BIOBUF); 3812 } 3813 bufspace_adjust(bp, newbsize); 3814 } 3815 3816 /* 3817 * This code constitutes the buffer memory from either anonymous system 3818 * memory (in the case of non-VMIO operations) or from an associated 3819 * VM object (in the case of VMIO operations). This code is able to 3820 * resize a buffer up or down. 3821 * 3822 * Note that this code is tricky, and has many complications to resolve 3823 * deadlock or inconsistent data situations. Tread lightly!!! 3824 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 3825 * the caller. Calling this code willy nilly can result in the loss of data. 3826 * 3827 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 3828 * B_CACHE for the non-VMIO case. 3829 */ 3830 int 3831 allocbuf(struct buf *bp, int size) 3832 { 3833 int newbsize; 3834 3835 BUF_ASSERT_HELD(bp); 3836 3837 if (bp->b_bcount == size) 3838 return (1); 3839 3840 if (bp->b_kvasize != 0 && bp->b_kvasize < size) 3841 panic("allocbuf: buffer too small"); 3842 3843 newbsize = roundup2(size, DEV_BSIZE); 3844 if ((bp->b_flags & B_VMIO) == 0) { 3845 if ((bp->b_flags & B_MALLOC) == 0) 3846 newbsize = round_page(newbsize); 3847 /* 3848 * Just get anonymous memory from the kernel. Don't 3849 * mess with B_CACHE. 3850 */ 3851 if (newbsize < bp->b_bufsize) 3852 vfs_nonvmio_truncate(bp, newbsize); 3853 else if (newbsize > bp->b_bufsize) 3854 vfs_nonvmio_extend(bp, newbsize); 3855 } else { 3856 int desiredpages; 3857 3858 desiredpages = (size == 0) ? 0 : 3859 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 3860 3861 if (bp->b_flags & B_MALLOC) 3862 panic("allocbuf: VMIO buffer can't be malloced"); 3863 /* 3864 * Set B_CACHE initially if buffer is 0 length or will become 3865 * 0-length. 3866 */ 3867 if (size == 0 || bp->b_bufsize == 0) 3868 bp->b_flags |= B_CACHE; 3869 3870 if (newbsize < bp->b_bufsize) 3871 vfs_vmio_truncate(bp, desiredpages); 3872 /* XXX This looks as if it should be newbsize > b_bufsize */ 3873 else if (size > bp->b_bcount) 3874 vfs_vmio_extend(bp, desiredpages, size); 3875 bufspace_adjust(bp, newbsize); 3876 } 3877 bp->b_bcount = size; /* requested buffer size. */ 3878 return (1); 3879 } 3880 3881 extern int inflight_transient_maps; 3882 3883 void 3884 biodone(struct bio *bp) 3885 { 3886 struct mtx *mtxp; 3887 void (*done)(struct bio *); 3888 vm_offset_t start, end; 3889 3890 biotrack(bp, __func__); 3891 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) { 3892 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING; 3893 bp->bio_flags |= BIO_UNMAPPED; 3894 start = trunc_page((vm_offset_t)bp->bio_data); 3895 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length); 3896 bp->bio_data = unmapped_buf; 3897 pmap_qremove(start, OFF_TO_IDX(end - start)); 3898 vmem_free(transient_arena, start, end - start); 3899 atomic_add_int(&inflight_transient_maps, -1); 3900 } 3901 done = bp->bio_done; 3902 if (done == NULL) { 3903 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3904 mtx_lock(mtxp); 3905 bp->bio_flags |= BIO_DONE; 3906 wakeup(bp); 3907 mtx_unlock(mtxp); 3908 } else { 3909 bp->bio_flags |= BIO_DONE; 3910 done(bp); 3911 } 3912 } 3913 3914 /* 3915 * Wait for a BIO to finish. 3916 */ 3917 int 3918 biowait(struct bio *bp, const char *wchan) 3919 { 3920 struct mtx *mtxp; 3921 3922 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3923 mtx_lock(mtxp); 3924 while ((bp->bio_flags & BIO_DONE) == 0) 3925 msleep(bp, mtxp, PRIBIO, wchan, 0); 3926 mtx_unlock(mtxp); 3927 if (bp->bio_error != 0) 3928 return (bp->bio_error); 3929 if (!(bp->bio_flags & BIO_ERROR)) 3930 return (0); 3931 return (EIO); 3932 } 3933 3934 void 3935 biofinish(struct bio *bp, struct devstat *stat, int error) 3936 { 3937 3938 if (error) { 3939 bp->bio_error = error; 3940 bp->bio_flags |= BIO_ERROR; 3941 } 3942 if (stat != NULL) 3943 devstat_end_transaction_bio(stat, bp); 3944 biodone(bp); 3945 } 3946 3947 #if defined(BUF_TRACKING) || defined(FULL_BUF_TRACKING) 3948 void 3949 biotrack_buf(struct bio *bp, const char *location) 3950 { 3951 3952 buf_track(bp->bio_track_bp, location); 3953 } 3954 #endif 3955 3956 /* 3957 * bufwait: 3958 * 3959 * Wait for buffer I/O completion, returning error status. The buffer 3960 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3961 * error and cleared. 3962 */ 3963 int 3964 bufwait(struct buf *bp) 3965 { 3966 if (bp->b_iocmd == BIO_READ) 3967 bwait(bp, PRIBIO, "biord"); 3968 else 3969 bwait(bp, PRIBIO, "biowr"); 3970 if (bp->b_flags & B_EINTR) { 3971 bp->b_flags &= ~B_EINTR; 3972 return (EINTR); 3973 } 3974 if (bp->b_ioflags & BIO_ERROR) { 3975 return (bp->b_error ? bp->b_error : EIO); 3976 } else { 3977 return (0); 3978 } 3979 } 3980 3981 /* 3982 * bufdone: 3983 * 3984 * Finish I/O on a buffer, optionally calling a completion function. 3985 * This is usually called from an interrupt so process blocking is 3986 * not allowed. 3987 * 3988 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3989 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3990 * assuming B_INVAL is clear. 3991 * 3992 * For the VMIO case, we set B_CACHE if the op was a read and no 3993 * read error occurred, or if the op was a write. B_CACHE is never 3994 * set if the buffer is invalid or otherwise uncacheable. 3995 * 3996 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3997 * initiator to leave B_INVAL set to brelse the buffer out of existence 3998 * in the biodone routine. 3999 */ 4000 void 4001 bufdone(struct buf *bp) 4002 { 4003 struct bufobj *dropobj; 4004 void (*biodone)(struct buf *); 4005 4006 buf_track(bp, __func__); 4007 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 4008 dropobj = NULL; 4009 4010 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 4011 BUF_ASSERT_HELD(bp); 4012 4013 runningbufwakeup(bp); 4014 if (bp->b_iocmd == BIO_WRITE) 4015 dropobj = bp->b_bufobj; 4016 /* call optional completion function if requested */ 4017 if (bp->b_iodone != NULL) { 4018 biodone = bp->b_iodone; 4019 bp->b_iodone = NULL; 4020 (*biodone) (bp); 4021 if (dropobj) 4022 bufobj_wdrop(dropobj); 4023 return; 4024 } 4025 4026 bufdone_finish(bp); 4027 4028 if (dropobj) 4029 bufobj_wdrop(dropobj); 4030 } 4031 4032 void 4033 bufdone_finish(struct buf *bp) 4034 { 4035 BUF_ASSERT_HELD(bp); 4036 4037 if (!LIST_EMPTY(&bp->b_dep)) 4038 buf_complete(bp); 4039 4040 if (bp->b_flags & B_VMIO) { 4041 /* 4042 * Set B_CACHE if the op was a normal read and no error 4043 * occurred. B_CACHE is set for writes in the b*write() 4044 * routines. 4045 */ 4046 if (bp->b_iocmd == BIO_READ && 4047 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 4048 !(bp->b_ioflags & BIO_ERROR)) 4049 bp->b_flags |= B_CACHE; 4050 vfs_vmio_iodone(bp); 4051 } 4052 4053 /* 4054 * For asynchronous completions, release the buffer now. The brelse 4055 * will do a wakeup there if necessary - so no need to do a wakeup 4056 * here in the async case. The sync case always needs to do a wakeup. 4057 */ 4058 if (bp->b_flags & B_ASYNC) { 4059 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || 4060 (bp->b_ioflags & BIO_ERROR)) 4061 brelse(bp); 4062 else 4063 bqrelse(bp); 4064 } else 4065 bdone(bp); 4066 } 4067 4068 /* 4069 * This routine is called in lieu of iodone in the case of 4070 * incomplete I/O. This keeps the busy status for pages 4071 * consistent. 4072 */ 4073 void 4074 vfs_unbusy_pages(struct buf *bp) 4075 { 4076 int i; 4077 vm_object_t obj; 4078 vm_page_t m; 4079 4080 runningbufwakeup(bp); 4081 if (!(bp->b_flags & B_VMIO)) 4082 return; 4083 4084 obj = bp->b_bufobj->bo_object; 4085 VM_OBJECT_WLOCK(obj); 4086 for (i = 0; i < bp->b_npages; i++) { 4087 m = bp->b_pages[i]; 4088 if (m == bogus_page) { 4089 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 4090 if (!m) 4091 panic("vfs_unbusy_pages: page missing\n"); 4092 bp->b_pages[i] = m; 4093 if (buf_mapped(bp)) { 4094 BUF_CHECK_MAPPED(bp); 4095 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4096 bp->b_pages, bp->b_npages); 4097 } else 4098 BUF_CHECK_UNMAPPED(bp); 4099 } 4100 vm_page_sunbusy(m); 4101 } 4102 vm_object_pip_wakeupn(obj, bp->b_npages); 4103 VM_OBJECT_WUNLOCK(obj); 4104 } 4105 4106 /* 4107 * vfs_page_set_valid: 4108 * 4109 * Set the valid bits in a page based on the supplied offset. The 4110 * range is restricted to the buffer's size. 4111 * 4112 * This routine is typically called after a read completes. 4113 */ 4114 static void 4115 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4116 { 4117 vm_ooffset_t eoff; 4118 4119 /* 4120 * Compute the end offset, eoff, such that [off, eoff) does not span a 4121 * page boundary and eoff is not greater than the end of the buffer. 4122 * The end of the buffer, in this case, is our file EOF, not the 4123 * allocation size of the buffer. 4124 */ 4125 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 4126 if (eoff > bp->b_offset + bp->b_bcount) 4127 eoff = bp->b_offset + bp->b_bcount; 4128 4129 /* 4130 * Set valid range. This is typically the entire buffer and thus the 4131 * entire page. 4132 */ 4133 if (eoff > off) 4134 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off); 4135 } 4136 4137 /* 4138 * vfs_page_set_validclean: 4139 * 4140 * Set the valid bits and clear the dirty bits in a page based on the 4141 * supplied offset. The range is restricted to the buffer's size. 4142 */ 4143 static void 4144 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4145 { 4146 vm_ooffset_t soff, eoff; 4147 4148 /* 4149 * Start and end offsets in buffer. eoff - soff may not cross a 4150 * page boundary or cross the end of the buffer. The end of the 4151 * buffer, in this case, is our file EOF, not the allocation size 4152 * of the buffer. 4153 */ 4154 soff = off; 4155 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4156 if (eoff > bp->b_offset + bp->b_bcount) 4157 eoff = bp->b_offset + bp->b_bcount; 4158 4159 /* 4160 * Set valid range. This is typically the entire buffer and thus the 4161 * entire page. 4162 */ 4163 if (eoff > soff) { 4164 vm_page_set_validclean( 4165 m, 4166 (vm_offset_t) (soff & PAGE_MASK), 4167 (vm_offset_t) (eoff - soff) 4168 ); 4169 } 4170 } 4171 4172 /* 4173 * Ensure that all buffer pages are not exclusive busied. If any page is 4174 * exclusive busy, drain it. 4175 */ 4176 void 4177 vfs_drain_busy_pages(struct buf *bp) 4178 { 4179 vm_page_t m; 4180 int i, last_busied; 4181 4182 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object); 4183 last_busied = 0; 4184 for (i = 0; i < bp->b_npages; i++) { 4185 m = bp->b_pages[i]; 4186 if (vm_page_xbusied(m)) { 4187 for (; last_busied < i; last_busied++) 4188 vm_page_sbusy(bp->b_pages[last_busied]); 4189 while (vm_page_xbusied(m)) { 4190 vm_page_lock(m); 4191 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4192 vm_page_busy_sleep(m, "vbpage", true); 4193 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4194 } 4195 } 4196 } 4197 for (i = 0; i < last_busied; i++) 4198 vm_page_sunbusy(bp->b_pages[i]); 4199 } 4200 4201 /* 4202 * This routine is called before a device strategy routine. 4203 * It is used to tell the VM system that paging I/O is in 4204 * progress, and treat the pages associated with the buffer 4205 * almost as being exclusive busy. Also the object paging_in_progress 4206 * flag is handled to make sure that the object doesn't become 4207 * inconsistent. 4208 * 4209 * Since I/O has not been initiated yet, certain buffer flags 4210 * such as BIO_ERROR or B_INVAL may be in an inconsistent state 4211 * and should be ignored. 4212 */ 4213 void 4214 vfs_busy_pages(struct buf *bp, int clear_modify) 4215 { 4216 int i, bogus; 4217 vm_object_t obj; 4218 vm_ooffset_t foff; 4219 vm_page_t m; 4220 4221 if (!(bp->b_flags & B_VMIO)) 4222 return; 4223 4224 obj = bp->b_bufobj->bo_object; 4225 foff = bp->b_offset; 4226 KASSERT(bp->b_offset != NOOFFSET, 4227 ("vfs_busy_pages: no buffer offset")); 4228 VM_OBJECT_WLOCK(obj); 4229 vfs_drain_busy_pages(bp); 4230 if (bp->b_bufsize != 0) 4231 vfs_setdirty_locked_object(bp); 4232 bogus = 0; 4233 for (i = 0; i < bp->b_npages; i++) { 4234 m = bp->b_pages[i]; 4235 4236 if ((bp->b_flags & B_CLUSTER) == 0) { 4237 vm_object_pip_add(obj, 1); 4238 vm_page_sbusy(m); 4239 } 4240 /* 4241 * When readying a buffer for a read ( i.e 4242 * clear_modify == 0 ), it is important to do 4243 * bogus_page replacement for valid pages in 4244 * partially instantiated buffers. Partially 4245 * instantiated buffers can, in turn, occur when 4246 * reconstituting a buffer from its VM backing store 4247 * base. We only have to do this if B_CACHE is 4248 * clear ( which causes the I/O to occur in the 4249 * first place ). The replacement prevents the read 4250 * I/O from overwriting potentially dirty VM-backed 4251 * pages. XXX bogus page replacement is, uh, bogus. 4252 * It may not work properly with small-block devices. 4253 * We need to find a better way. 4254 */ 4255 if (clear_modify) { 4256 pmap_remove_write(m); 4257 vfs_page_set_validclean(bp, foff, m); 4258 } else if (m->valid == VM_PAGE_BITS_ALL && 4259 (bp->b_flags & B_CACHE) == 0) { 4260 bp->b_pages[i] = bogus_page; 4261 bogus++; 4262 } 4263 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4264 } 4265 VM_OBJECT_WUNLOCK(obj); 4266 if (bogus && buf_mapped(bp)) { 4267 BUF_CHECK_MAPPED(bp); 4268 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4269 bp->b_pages, bp->b_npages); 4270 } 4271 } 4272 4273 /* 4274 * vfs_bio_set_valid: 4275 * 4276 * Set the range within the buffer to valid. The range is 4277 * relative to the beginning of the buffer, b_offset. Note that 4278 * b_offset itself may be offset from the beginning of the first 4279 * page. 4280 */ 4281 void 4282 vfs_bio_set_valid(struct buf *bp, int base, int size) 4283 { 4284 int i, n; 4285 vm_page_t m; 4286 4287 if (!(bp->b_flags & B_VMIO)) 4288 return; 4289 4290 /* 4291 * Fixup base to be relative to beginning of first page. 4292 * Set initial n to be the maximum number of bytes in the 4293 * first page that can be validated. 4294 */ 4295 base += (bp->b_offset & PAGE_MASK); 4296 n = PAGE_SIZE - (base & PAGE_MASK); 4297 4298 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4299 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4300 m = bp->b_pages[i]; 4301 if (n > size) 4302 n = size; 4303 vm_page_set_valid_range(m, base & PAGE_MASK, n); 4304 base += n; 4305 size -= n; 4306 n = PAGE_SIZE; 4307 } 4308 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4309 } 4310 4311 /* 4312 * vfs_bio_clrbuf: 4313 * 4314 * If the specified buffer is a non-VMIO buffer, clear the entire 4315 * buffer. If the specified buffer is a VMIO buffer, clear and 4316 * validate only the previously invalid portions of the buffer. 4317 * This routine essentially fakes an I/O, so we need to clear 4318 * BIO_ERROR and B_INVAL. 4319 * 4320 * Note that while we only theoretically need to clear through b_bcount, 4321 * we go ahead and clear through b_bufsize. 4322 */ 4323 void 4324 vfs_bio_clrbuf(struct buf *bp) 4325 { 4326 int i, j, mask, sa, ea, slide; 4327 4328 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 4329 clrbuf(bp); 4330 return; 4331 } 4332 bp->b_flags &= ~B_INVAL; 4333 bp->b_ioflags &= ~BIO_ERROR; 4334 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4335 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 4336 (bp->b_offset & PAGE_MASK) == 0) { 4337 if (bp->b_pages[0] == bogus_page) 4338 goto unlock; 4339 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 4340 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object); 4341 if ((bp->b_pages[0]->valid & mask) == mask) 4342 goto unlock; 4343 if ((bp->b_pages[0]->valid & mask) == 0) { 4344 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize); 4345 bp->b_pages[0]->valid |= mask; 4346 goto unlock; 4347 } 4348 } 4349 sa = bp->b_offset & PAGE_MASK; 4350 slide = 0; 4351 for (i = 0; i < bp->b_npages; i++, sa = 0) { 4352 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize); 4353 ea = slide & PAGE_MASK; 4354 if (ea == 0) 4355 ea = PAGE_SIZE; 4356 if (bp->b_pages[i] == bogus_page) 4357 continue; 4358 j = sa / DEV_BSIZE; 4359 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 4360 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object); 4361 if ((bp->b_pages[i]->valid & mask) == mask) 4362 continue; 4363 if ((bp->b_pages[i]->valid & mask) == 0) 4364 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa); 4365 else { 4366 for (; sa < ea; sa += DEV_BSIZE, j++) { 4367 if ((bp->b_pages[i]->valid & (1 << j)) == 0) { 4368 pmap_zero_page_area(bp->b_pages[i], 4369 sa, DEV_BSIZE); 4370 } 4371 } 4372 } 4373 bp->b_pages[i]->valid |= mask; 4374 } 4375 unlock: 4376 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4377 bp->b_resid = 0; 4378 } 4379 4380 void 4381 vfs_bio_bzero_buf(struct buf *bp, int base, int size) 4382 { 4383 vm_page_t m; 4384 int i, n; 4385 4386 if (buf_mapped(bp)) { 4387 BUF_CHECK_MAPPED(bp); 4388 bzero(bp->b_data + base, size); 4389 } else { 4390 BUF_CHECK_UNMAPPED(bp); 4391 n = PAGE_SIZE - (base & PAGE_MASK); 4392 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4393 m = bp->b_pages[i]; 4394 if (n > size) 4395 n = size; 4396 pmap_zero_page_area(m, base & PAGE_MASK, n); 4397 base += n; 4398 size -= n; 4399 n = PAGE_SIZE; 4400 } 4401 } 4402 } 4403 4404 /* 4405 * Update buffer flags based on I/O request parameters, optionally releasing the 4406 * buffer. If it's VMIO or direct I/O, the buffer pages are released to the VM, 4407 * where they may be placed on a page queue (VMIO) or freed immediately (direct 4408 * I/O). Otherwise the buffer is released to the cache. 4409 */ 4410 static void 4411 b_io_dismiss(struct buf *bp, int ioflag, bool release) 4412 { 4413 4414 KASSERT((ioflag & IO_NOREUSE) == 0 || (ioflag & IO_VMIO) != 0, 4415 ("buf %p non-VMIO noreuse", bp)); 4416 4417 if ((ioflag & IO_DIRECT) != 0) 4418 bp->b_flags |= B_DIRECT; 4419 if ((ioflag & (IO_VMIO | IO_DIRECT)) != 0 && LIST_EMPTY(&bp->b_dep)) { 4420 bp->b_flags |= B_RELBUF; 4421 if ((ioflag & IO_NOREUSE) != 0) 4422 bp->b_flags |= B_NOREUSE; 4423 if (release) 4424 brelse(bp); 4425 } else if (release) 4426 bqrelse(bp); 4427 } 4428 4429 void 4430 vfs_bio_brelse(struct buf *bp, int ioflag) 4431 { 4432 4433 b_io_dismiss(bp, ioflag, true); 4434 } 4435 4436 void 4437 vfs_bio_set_flags(struct buf *bp, int ioflag) 4438 { 4439 4440 b_io_dismiss(bp, ioflag, false); 4441 } 4442 4443 /* 4444 * vm_hold_load_pages and vm_hold_free_pages get pages into 4445 * a buffers address space. The pages are anonymous and are 4446 * not associated with a file object. 4447 */ 4448 static void 4449 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4450 { 4451 vm_offset_t pg; 4452 vm_page_t p; 4453 int index; 4454 4455 BUF_CHECK_MAPPED(bp); 4456 4457 to = round_page(to); 4458 from = round_page(from); 4459 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4460 4461 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 4462 tryagain: 4463 /* 4464 * note: must allocate system pages since blocking here 4465 * could interfere with paging I/O, no matter which 4466 * process we are. 4467 */ 4468 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ | 4469 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT)); 4470 if (p == NULL) { 4471 VM_WAIT; 4472 goto tryagain; 4473 } 4474 pmap_qenter(pg, &p, 1); 4475 bp->b_pages[index] = p; 4476 } 4477 bp->b_npages = index; 4478 } 4479 4480 /* Return pages associated with this buf to the vm system */ 4481 static void 4482 vm_hold_free_pages(struct buf *bp, int newbsize) 4483 { 4484 vm_offset_t from; 4485 vm_page_t p; 4486 int index, newnpages; 4487 4488 BUF_CHECK_MAPPED(bp); 4489 4490 from = round_page((vm_offset_t)bp->b_data + newbsize); 4491 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4492 if (bp->b_npages > newnpages) 4493 pmap_qremove(from, bp->b_npages - newnpages); 4494 for (index = newnpages; index < bp->b_npages; index++) { 4495 p = bp->b_pages[index]; 4496 bp->b_pages[index] = NULL; 4497 if (vm_page_sbusied(p)) 4498 printf("vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 4499 (intmax_t)bp->b_blkno, (intmax_t)bp->b_lblkno); 4500 p->wire_count--; 4501 vm_page_free(p); 4502 atomic_subtract_int(&vm_cnt.v_wire_count, 1); 4503 } 4504 bp->b_npages = newnpages; 4505 } 4506 4507 /* 4508 * Map an IO request into kernel virtual address space. 4509 * 4510 * All requests are (re)mapped into kernel VA space. 4511 * Notice that we use b_bufsize for the size of the buffer 4512 * to be mapped. b_bcount might be modified by the driver. 4513 * 4514 * Note that even if the caller determines that the address space should 4515 * be valid, a race or a smaller-file mapped into a larger space may 4516 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 4517 * check the return value. 4518 * 4519 * This function only works with pager buffers. 4520 */ 4521 int 4522 vmapbuf(struct buf *bp, int mapbuf) 4523 { 4524 vm_prot_t prot; 4525 int pidx; 4526 4527 if (bp->b_bufsize < 0) 4528 return (-1); 4529 prot = VM_PROT_READ; 4530 if (bp->b_iocmd == BIO_READ) 4531 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 4532 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 4533 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages, 4534 btoc(MAXPHYS))) < 0) 4535 return (-1); 4536 bp->b_npages = pidx; 4537 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK; 4538 if (mapbuf || !unmapped_buf_allowed) { 4539 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_pages, pidx); 4540 bp->b_data = bp->b_kvabase + bp->b_offset; 4541 } else 4542 bp->b_data = unmapped_buf; 4543 return(0); 4544 } 4545 4546 /* 4547 * Free the io map PTEs associated with this IO operation. 4548 * We also invalidate the TLB entries and restore the original b_addr. 4549 * 4550 * This function only works with pager buffers. 4551 */ 4552 void 4553 vunmapbuf(struct buf *bp) 4554 { 4555 int npages; 4556 4557 npages = bp->b_npages; 4558 if (buf_mapped(bp)) 4559 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 4560 vm_page_unhold_pages(bp->b_pages, npages); 4561 4562 bp->b_data = unmapped_buf; 4563 } 4564 4565 void 4566 bdone(struct buf *bp) 4567 { 4568 struct mtx *mtxp; 4569 4570 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4571 mtx_lock(mtxp); 4572 bp->b_flags |= B_DONE; 4573 wakeup(bp); 4574 mtx_unlock(mtxp); 4575 } 4576 4577 void 4578 bwait(struct buf *bp, u_char pri, const char *wchan) 4579 { 4580 struct mtx *mtxp; 4581 4582 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4583 mtx_lock(mtxp); 4584 while ((bp->b_flags & B_DONE) == 0) 4585 msleep(bp, mtxp, pri, wchan, 0); 4586 mtx_unlock(mtxp); 4587 } 4588 4589 int 4590 bufsync(struct bufobj *bo, int waitfor) 4591 { 4592 4593 return (VOP_FSYNC(bo2vnode(bo), waitfor, curthread)); 4594 } 4595 4596 void 4597 bufstrategy(struct bufobj *bo, struct buf *bp) 4598 { 4599 int i = 0; 4600 struct vnode *vp; 4601 4602 vp = bp->b_vp; 4603 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 4604 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 4605 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 4606 i = VOP_STRATEGY(vp, bp); 4607 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 4608 } 4609 4610 void 4611 bufobj_wrefl(struct bufobj *bo) 4612 { 4613 4614 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4615 ASSERT_BO_WLOCKED(bo); 4616 bo->bo_numoutput++; 4617 } 4618 4619 void 4620 bufobj_wref(struct bufobj *bo) 4621 { 4622 4623 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4624 BO_LOCK(bo); 4625 bo->bo_numoutput++; 4626 BO_UNLOCK(bo); 4627 } 4628 4629 void 4630 bufobj_wdrop(struct bufobj *bo) 4631 { 4632 4633 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 4634 BO_LOCK(bo); 4635 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 4636 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 4637 bo->bo_flag &= ~BO_WWAIT; 4638 wakeup(&bo->bo_numoutput); 4639 } 4640 BO_UNLOCK(bo); 4641 } 4642 4643 int 4644 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 4645 { 4646 int error; 4647 4648 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 4649 ASSERT_BO_WLOCKED(bo); 4650 error = 0; 4651 while (bo->bo_numoutput) { 4652 bo->bo_flag |= BO_WWAIT; 4653 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo), 4654 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 4655 if (error) 4656 break; 4657 } 4658 return (error); 4659 } 4660 4661 /* 4662 * Set bio_data or bio_ma for struct bio from the struct buf. 4663 */ 4664 void 4665 bdata2bio(struct buf *bp, struct bio *bip) 4666 { 4667 4668 if (!buf_mapped(bp)) { 4669 KASSERT(unmapped_buf_allowed, ("unmapped")); 4670 bip->bio_ma = bp->b_pages; 4671 bip->bio_ma_n = bp->b_npages; 4672 bip->bio_data = unmapped_buf; 4673 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 4674 bip->bio_flags |= BIO_UNMAPPED; 4675 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) / 4676 PAGE_SIZE == bp->b_npages, 4677 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset, 4678 (long long)bip->bio_length, bip->bio_ma_n)); 4679 } else { 4680 bip->bio_data = bp->b_data; 4681 bip->bio_ma = NULL; 4682 } 4683 } 4684 4685 /* 4686 * The MIPS pmap code currently doesn't handle aliased pages. 4687 * The VIPT caches may not handle page aliasing themselves, leading 4688 * to data corruption. 4689 * 4690 * As such, this code makes a system extremely unhappy if said 4691 * system doesn't support unaliasing the above situation in hardware. 4692 * Some "recent" systems (eg some mips24k/mips74k cores) don't enable 4693 * this feature at build time, so it has to be handled in software. 4694 * 4695 * Once the MIPS pmap/cache code grows to support this function on 4696 * earlier chips, it should be flipped back off. 4697 */ 4698 #ifdef __mips__ 4699 static int buf_pager_relbuf = 1; 4700 #else 4701 static int buf_pager_relbuf = 0; 4702 #endif 4703 SYSCTL_INT(_vfs, OID_AUTO, buf_pager_relbuf, CTLFLAG_RWTUN, 4704 &buf_pager_relbuf, 0, 4705 "Make buffer pager release buffers after reading"); 4706 4707 /* 4708 * The buffer pager. It uses buffer reads to validate pages. 4709 * 4710 * In contrast to the generic local pager from vm/vnode_pager.c, this 4711 * pager correctly and easily handles volumes where the underlying 4712 * device block size is greater than the machine page size. The 4713 * buffer cache transparently extends the requested page run to be 4714 * aligned at the block boundary, and does the necessary bogus page 4715 * replacements in the addends to avoid obliterating already valid 4716 * pages. 4717 * 4718 * The only non-trivial issue is that the exclusive busy state for 4719 * pages, which is assumed by the vm_pager_getpages() interface, is 4720 * incompatible with the VMIO buffer cache's desire to share-busy the 4721 * pages. This function performs a trivial downgrade of the pages' 4722 * state before reading buffers, and a less trivial upgrade from the 4723 * shared-busy to excl-busy state after the read. 4724 */ 4725 int 4726 vfs_bio_getpages(struct vnode *vp, vm_page_t *ma, int count, 4727 int *rbehind, int *rahead, vbg_get_lblkno_t get_lblkno, 4728 vbg_get_blksize_t get_blksize) 4729 { 4730 vm_page_t m; 4731 vm_object_t object; 4732 struct buf *bp; 4733 struct mount *mp; 4734 daddr_t lbn, lbnp; 4735 vm_ooffset_t la, lb, poff, poffe; 4736 long bsize; 4737 int bo_bs, br_flags, error, i, pgsin, pgsin_a, pgsin_b; 4738 bool redo, lpart; 4739 4740 object = vp->v_object; 4741 mp = vp->v_mount; 4742 la = IDX_TO_OFF(ma[count - 1]->pindex); 4743 if (la >= object->un_pager.vnp.vnp_size) 4744 return (VM_PAGER_BAD); 4745 lpart = la + PAGE_SIZE > object->un_pager.vnp.vnp_size; 4746 bo_bs = get_blksize(vp, get_lblkno(vp, IDX_TO_OFF(ma[0]->pindex))); 4747 4748 /* 4749 * Calculate read-ahead, behind and total pages. 4750 */ 4751 pgsin = count; 4752 lb = IDX_TO_OFF(ma[0]->pindex); 4753 pgsin_b = OFF_TO_IDX(lb - rounddown2(lb, bo_bs)); 4754 pgsin += pgsin_b; 4755 if (rbehind != NULL) 4756 *rbehind = pgsin_b; 4757 pgsin_a = OFF_TO_IDX(roundup2(la, bo_bs) - la); 4758 if (la + IDX_TO_OFF(pgsin_a) >= object->un_pager.vnp.vnp_size) 4759 pgsin_a = OFF_TO_IDX(roundup2(object->un_pager.vnp.vnp_size, 4760 PAGE_SIZE) - la); 4761 pgsin += pgsin_a; 4762 if (rahead != NULL) 4763 *rahead = pgsin_a; 4764 PCPU_INC(cnt.v_vnodein); 4765 PCPU_ADD(cnt.v_vnodepgsin, pgsin); 4766 4767 br_flags = (mp != NULL && (mp->mnt_kern_flag & MNTK_UNMAPPED_BUFS) 4768 != 0) ? GB_UNMAPPED : 0; 4769 VM_OBJECT_WLOCK(object); 4770 again: 4771 for (i = 0; i < count; i++) 4772 vm_page_busy_downgrade(ma[i]); 4773 VM_OBJECT_WUNLOCK(object); 4774 4775 lbnp = -1; 4776 for (i = 0; i < count; i++) { 4777 m = ma[i]; 4778 4779 /* 4780 * Pages are shared busy and the object lock is not 4781 * owned, which together allow for the pages' 4782 * invalidation. The racy test for validity avoids 4783 * useless creation of the buffer for the most typical 4784 * case when invalidation is not used in redo or for 4785 * parallel read. The shared->excl upgrade loop at 4786 * the end of the function catches the race in a 4787 * reliable way (protected by the object lock). 4788 */ 4789 if (m->valid == VM_PAGE_BITS_ALL) 4790 continue; 4791 4792 poff = IDX_TO_OFF(m->pindex); 4793 poffe = MIN(poff + PAGE_SIZE, object->un_pager.vnp.vnp_size); 4794 for (; poff < poffe; poff += bsize) { 4795 lbn = get_lblkno(vp, poff); 4796 if (lbn == lbnp) 4797 goto next_page; 4798 lbnp = lbn; 4799 4800 bsize = get_blksize(vp, lbn); 4801 error = bread_gb(vp, lbn, bsize, curthread->td_ucred, 4802 br_flags, &bp); 4803 if (error != 0) 4804 goto end_pages; 4805 if (LIST_EMPTY(&bp->b_dep)) { 4806 /* 4807 * Invalidation clears m->valid, but 4808 * may leave B_CACHE flag if the 4809 * buffer existed at the invalidation 4810 * time. In this case, recycle the 4811 * buffer to do real read on next 4812 * bread() after redo. 4813 * 4814 * Otherwise B_RELBUF is not strictly 4815 * necessary, enable to reduce buf 4816 * cache pressure. 4817 */ 4818 if (buf_pager_relbuf || 4819 m->valid != VM_PAGE_BITS_ALL) 4820 bp->b_flags |= B_RELBUF; 4821 4822 bp->b_flags &= ~B_NOCACHE; 4823 brelse(bp); 4824 } else { 4825 bqrelse(bp); 4826 } 4827 } 4828 KASSERT(1 /* racy, enable for debugging */ || 4829 m->valid == VM_PAGE_BITS_ALL || i == count - 1, 4830 ("buf %d %p invalid", i, m)); 4831 if (i == count - 1 && lpart) { 4832 VM_OBJECT_WLOCK(object); 4833 if (m->valid != 0 && 4834 m->valid != VM_PAGE_BITS_ALL) 4835 vm_page_zero_invalid(m, TRUE); 4836 VM_OBJECT_WUNLOCK(object); 4837 } 4838 next_page:; 4839 } 4840 end_pages: 4841 4842 VM_OBJECT_WLOCK(object); 4843 redo = false; 4844 for (i = 0; i < count; i++) { 4845 vm_page_sunbusy(ma[i]); 4846 ma[i] = vm_page_grab(object, ma[i]->pindex, VM_ALLOC_NORMAL); 4847 4848 /* 4849 * Since the pages were only sbusy while neither the 4850 * buffer nor the object lock was held by us, or 4851 * reallocated while vm_page_grab() slept for busy 4852 * relinguish, they could have been invalidated. 4853 * Recheck the valid bits and re-read as needed. 4854 * 4855 * Note that the last page is made fully valid in the 4856 * read loop, and partial validity for the page at 4857 * index count - 1 could mean that the page was 4858 * invalidated or removed, so we must restart for 4859 * safety as well. 4860 */ 4861 if (ma[i]->valid != VM_PAGE_BITS_ALL) 4862 redo = true; 4863 } 4864 if (redo && error == 0) 4865 goto again; 4866 VM_OBJECT_WUNLOCK(object); 4867 return (error != 0 ? VM_PAGER_ERROR : VM_PAGER_OK); 4868 } 4869 4870 #include "opt_ddb.h" 4871 #ifdef DDB 4872 #include <ddb/ddb.h> 4873 4874 /* DDB command to show buffer data */ 4875 DB_SHOW_COMMAND(buffer, db_show_buffer) 4876 { 4877 /* get args */ 4878 struct buf *bp = (struct buf *)addr; 4879 #ifdef FULL_BUF_TRACKING 4880 uint32_t i, j; 4881 #endif 4882 4883 if (!have_addr) { 4884 db_printf("usage: show buffer <addr>\n"); 4885 return; 4886 } 4887 4888 db_printf("buf at %p\n", bp); 4889 db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n", 4890 (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags, 4891 PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS); 4892 db_printf( 4893 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 4894 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, " 4895 "b_dep = %p\n", 4896 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 4897 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 4898 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first); 4899 db_printf("b_kvabase = %p, b_kvasize = %d\n", 4900 bp->b_kvabase, bp->b_kvasize); 4901 if (bp->b_npages) { 4902 int i; 4903 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 4904 for (i = 0; i < bp->b_npages; i++) { 4905 vm_page_t m; 4906 m = bp->b_pages[i]; 4907 if (m != NULL) 4908 db_printf("(%p, 0x%lx, 0x%lx)", m->object, 4909 (u_long)m->pindex, 4910 (u_long)VM_PAGE_TO_PHYS(m)); 4911 else 4912 db_printf("( ??? )"); 4913 if ((i + 1) < bp->b_npages) 4914 db_printf(","); 4915 } 4916 db_printf("\n"); 4917 } 4918 #if defined(FULL_BUF_TRACKING) 4919 db_printf("b_io_tracking: b_io_tcnt = %u\n", bp->b_io_tcnt); 4920 4921 i = bp->b_io_tcnt % BUF_TRACKING_SIZE; 4922 for (j = 1; j <= BUF_TRACKING_SIZE; j++) 4923 db_printf(" %2u: %s\n", j, 4924 bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)]); 4925 #elif defined(BUF_TRACKING) 4926 db_printf("b_io_tracking: %s\n", bp->b_io_tracking); 4927 #endif 4928 db_printf(" "); 4929 BUF_LOCKPRINTINFO(bp); 4930 } 4931 4932 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 4933 { 4934 struct buf *bp; 4935 int i; 4936 4937 for (i = 0; i < nbuf; i++) { 4938 bp = &buf[i]; 4939 if (BUF_ISLOCKED(bp)) { 4940 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4941 db_printf("\n"); 4942 } 4943 } 4944 } 4945 4946 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 4947 { 4948 struct vnode *vp; 4949 struct buf *bp; 4950 4951 if (!have_addr) { 4952 db_printf("usage: show vnodebufs <addr>\n"); 4953 return; 4954 } 4955 vp = (struct vnode *)addr; 4956 db_printf("Clean buffers:\n"); 4957 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 4958 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4959 db_printf("\n"); 4960 } 4961 db_printf("Dirty buffers:\n"); 4962 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 4963 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4964 db_printf("\n"); 4965 } 4966 } 4967 4968 DB_COMMAND(countfreebufs, db_coundfreebufs) 4969 { 4970 struct buf *bp; 4971 int i, used = 0, nfree = 0; 4972 4973 if (have_addr) { 4974 db_printf("usage: countfreebufs\n"); 4975 return; 4976 } 4977 4978 for (i = 0; i < nbuf; i++) { 4979 bp = &buf[i]; 4980 if (bp->b_qindex == QUEUE_EMPTY) 4981 nfree++; 4982 else 4983 used++; 4984 } 4985 4986 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 4987 nfree + used); 4988 db_printf("numfreebuffers is %d\n", numfreebuffers); 4989 } 4990 #endif /* DDB */ 4991