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 void breada(struct vnode *, daddr_t *, int *, int, struct ucred *, int, 123 void (*)(struct buf *)); 124 static int buf_flush(struct vnode *vp, int); 125 static int buf_recycle(bool); 126 static int buf_scan(bool); 127 static int flushbufqueues(struct vnode *, int, int); 128 static void buf_daemon(void); 129 static void bremfreel(struct buf *bp); 130 static __inline void bd_wakeup(void); 131 static int sysctl_runningspace(SYSCTL_HANDLER_ARGS); 132 static void bufkva_reclaim(vmem_t *, int); 133 static void bufkva_free(struct buf *); 134 static int buf_import(void *, void **, int, int); 135 static void buf_release(void *, void **, int); 136 static void maxbcachebuf_adjust(void); 137 138 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 139 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 140 static int sysctl_bufspace(SYSCTL_HANDLER_ARGS); 141 #endif 142 143 int vmiodirenable = TRUE; 144 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, 145 "Use the VM system for directory writes"); 146 long runningbufspace; 147 SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 148 "Amount of presently outstanding async buffer io"); 149 static long bufspace; 150 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 151 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 152 SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD, 153 &bufspace, 0, sysctl_bufspace, "L", "Virtual memory used for buffers"); 154 #else 155 SYSCTL_LONG(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, 156 "Physical memory used for buffers"); 157 #endif 158 static long bufkvaspace; 159 SYSCTL_LONG(_vfs, OID_AUTO, bufkvaspace, CTLFLAG_RD, &bufkvaspace, 0, 160 "Kernel virtual memory used for buffers"); 161 static long maxbufspace; 162 SYSCTL_LONG(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RW, &maxbufspace, 0, 163 "Maximum allowed value of bufspace (including metadata)"); 164 static long bufmallocspace; 165 SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 166 "Amount of malloced memory for buffers"); 167 static long maxbufmallocspace; 168 SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 169 0, "Maximum amount of malloced memory for buffers"); 170 static long lobufspace; 171 SYSCTL_LONG(_vfs, OID_AUTO, lobufspace, CTLFLAG_RW, &lobufspace, 0, 172 "Minimum amount of buffers we want to have"); 173 long hibufspace; 174 SYSCTL_LONG(_vfs, OID_AUTO, hibufspace, CTLFLAG_RW, &hibufspace, 0, 175 "Maximum allowed value of bufspace (excluding metadata)"); 176 long bufspacethresh; 177 SYSCTL_LONG(_vfs, OID_AUTO, bufspacethresh, CTLFLAG_RW, &bufspacethresh, 178 0, "Bufspace consumed before waking the daemon to free some"); 179 static int buffreekvacnt; 180 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0, 181 "Number of times we have freed the KVA space from some buffer"); 182 static int bufdefragcnt; 183 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0, 184 "Number of times we have had to repeat buffer allocation to defragment"); 185 static long lorunningspace; 186 SYSCTL_PROC(_vfs, OID_AUTO, lorunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE | 187 CTLFLAG_RW, &lorunningspace, 0, sysctl_runningspace, "L", 188 "Minimum preferred space used for in-progress I/O"); 189 static long hirunningspace; 190 SYSCTL_PROC(_vfs, OID_AUTO, hirunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE | 191 CTLFLAG_RW, &hirunningspace, 0, sysctl_runningspace, "L", 192 "Maximum amount of space to use for in-progress I/O"); 193 int dirtybufferflushes; 194 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes, 195 0, "Number of bdwrite to bawrite conversions to limit dirty buffers"); 196 int bdwriteskip; 197 SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip, 198 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk"); 199 int altbufferflushes; 200 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes, 201 0, "Number of fsync flushes to limit dirty buffers"); 202 static int recursiveflushes; 203 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes, 204 0, "Number of flushes skipped due to being recursive"); 205 static int numdirtybuffers; 206 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0, 207 "Number of buffers that are dirty (has unwritten changes) at the moment"); 208 static int lodirtybuffers; 209 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0, 210 "How many buffers we want to have free before bufdaemon can sleep"); 211 static int hidirtybuffers; 212 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0, 213 "When the number of dirty buffers is considered severe"); 214 int dirtybufthresh; 215 SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh, 216 0, "Number of bdwrite to bawrite conversions to clear dirty buffers"); 217 static int numfreebuffers; 218 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, 219 "Number of free buffers"); 220 static int lofreebuffers; 221 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0, 222 "Target number of free buffers"); 223 static int hifreebuffers; 224 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0, 225 "Threshold for clean buffer recycling"); 226 static int getnewbufcalls; 227 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0, 228 "Number of calls to getnewbuf"); 229 static int getnewbufrestarts; 230 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0, 231 "Number of times getnewbuf has had to restart a buffer acquisition"); 232 static int mappingrestarts; 233 SYSCTL_INT(_vfs, OID_AUTO, mappingrestarts, CTLFLAG_RW, &mappingrestarts, 0, 234 "Number of times getblk has had to restart a buffer mapping for " 235 "unmapped buffer"); 236 static int numbufallocfails; 237 SYSCTL_INT(_vfs, OID_AUTO, numbufallocfails, CTLFLAG_RW, &numbufallocfails, 0, 238 "Number of times buffer allocations failed"); 239 static int flushbufqtarget = 100; 240 SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0, 241 "Amount of work to do in flushbufqueues when helping bufdaemon"); 242 static long notbufdflushes; 243 SYSCTL_LONG(_vfs, OID_AUTO, notbufdflushes, CTLFLAG_RD, ¬bufdflushes, 0, 244 "Number of dirty buffer flushes done by the bufdaemon helpers"); 245 static long barrierwrites; 246 SYSCTL_LONG(_vfs, OID_AUTO, barrierwrites, CTLFLAG_RW, &barrierwrites, 0, 247 "Number of barrier writes"); 248 SYSCTL_INT(_vfs, OID_AUTO, unmapped_buf_allowed, CTLFLAG_RD, 249 &unmapped_buf_allowed, 0, 250 "Permit the use of the unmapped i/o"); 251 int maxbcachebuf = MAXBCACHEBUF; 252 SYSCTL_INT(_vfs, OID_AUTO, maxbcachebuf, CTLFLAG_RDTUN, &maxbcachebuf, 0, 253 "Maximum size of a buffer cache block"); 254 255 /* 256 * This lock synchronizes access to bd_request. 257 */ 258 static struct mtx_padalign __exclusive_cache_line bdlock; 259 260 /* 261 * This lock protects the runningbufreq and synchronizes runningbufwakeup and 262 * waitrunningbufspace(). 263 */ 264 static struct mtx_padalign __exclusive_cache_line rbreqlock; 265 266 /* 267 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it. 268 */ 269 static struct rwlock_padalign __exclusive_cache_line nblock; 270 271 /* 272 * Lock that protects bdirtywait. 273 */ 274 static struct mtx_padalign __exclusive_cache_line bdirtylock; 275 276 /* 277 * Wakeup point for bufdaemon, as well as indicator of whether it is already 278 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it 279 * is idling. 280 */ 281 static int bd_request; 282 283 /* 284 * Request/wakeup point for the bufspace daemon. 285 */ 286 static int bufspace_request; 287 288 /* 289 * Request for the buf daemon to write more buffers than is indicated by 290 * lodirtybuf. This may be necessary to push out excess dependencies or 291 * defragment the address space where a simple count of the number of dirty 292 * buffers is insufficient to characterize the demand for flushing them. 293 */ 294 static int bd_speedupreq; 295 296 /* 297 * Synchronization (sleep/wakeup) variable for active buffer space requests. 298 * Set when wait starts, cleared prior to wakeup(). 299 * Used in runningbufwakeup() and waitrunningbufspace(). 300 */ 301 static int runningbufreq; 302 303 /* 304 * Synchronization (sleep/wakeup) variable for buffer requests. 305 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done 306 * by and/or. 307 * Used in numdirtywakeup(), bufspace_wakeup(), bwillwrite(), 308 * getnewbuf(), and getblk(). 309 */ 310 static volatile int needsbuffer; 311 312 /* 313 * Synchronization for bwillwrite() waiters. 314 */ 315 static int bdirtywait; 316 317 /* 318 * Definitions for the buffer free lists. 319 */ 320 #define QUEUE_NONE 0 /* on no queue */ 321 #define QUEUE_EMPTY 1 /* empty buffer headers */ 322 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */ 323 #define QUEUE_CLEAN 3 /* non-B_DELWRI buffers */ 324 #define QUEUE_SENTINEL 1024 /* not an queue index, but mark for sentinel */ 325 326 /* Maximum number of clean buffer queues. */ 327 #define CLEAN_QUEUES 16 328 329 /* Configured number of clean queues. */ 330 static int clean_queues; 331 332 /* Maximum number of buffer queues. */ 333 #define BUFFER_QUEUES (QUEUE_CLEAN + CLEAN_QUEUES) 334 335 /* Queues for free buffers with various properties */ 336 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } }; 337 #ifdef INVARIANTS 338 static int bq_len[BUFFER_QUEUES]; 339 #endif 340 341 /* 342 * Lock for each bufqueue 343 */ 344 static struct mtx_padalign __exclusive_cache_line bqlocks[BUFFER_QUEUES]; 345 346 /* 347 * per-cpu empty buffer cache. 348 */ 349 uma_zone_t buf_zone; 350 351 /* 352 * Single global constant for BUF_WMESG, to avoid getting multiple references. 353 * buf_wmesg is referred from macros. 354 */ 355 const char *buf_wmesg = BUF_WMESG; 356 357 static int 358 sysctl_runningspace(SYSCTL_HANDLER_ARGS) 359 { 360 long value; 361 int error; 362 363 value = *(long *)arg1; 364 error = sysctl_handle_long(oidp, &value, 0, req); 365 if (error != 0 || req->newptr == NULL) 366 return (error); 367 mtx_lock(&rbreqlock); 368 if (arg1 == &hirunningspace) { 369 if (value < lorunningspace) 370 error = EINVAL; 371 else 372 hirunningspace = value; 373 } else { 374 KASSERT(arg1 == &lorunningspace, 375 ("%s: unknown arg1", __func__)); 376 if (value > hirunningspace) 377 error = EINVAL; 378 else 379 lorunningspace = value; 380 } 381 mtx_unlock(&rbreqlock); 382 return (error); 383 } 384 385 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 386 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 387 static int 388 sysctl_bufspace(SYSCTL_HANDLER_ARGS) 389 { 390 long lvalue; 391 int ivalue; 392 393 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long)) 394 return (sysctl_handle_long(oidp, arg1, arg2, req)); 395 lvalue = *(long *)arg1; 396 if (lvalue > INT_MAX) 397 /* On overflow, still write out a long to trigger ENOMEM. */ 398 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 399 ivalue = lvalue; 400 return (sysctl_handle_int(oidp, &ivalue, 0, req)); 401 } 402 #endif 403 404 static int 405 bqcleanq(void) 406 { 407 static int nextq; 408 409 return ((atomic_fetchadd_int(&nextq, 1) % clean_queues) + QUEUE_CLEAN); 410 } 411 412 static int 413 bqisclean(int qindex) 414 { 415 416 return (qindex >= QUEUE_CLEAN && qindex < QUEUE_CLEAN + CLEAN_QUEUES); 417 } 418 419 /* 420 * bqlock: 421 * 422 * Return the appropriate queue lock based on the index. 423 */ 424 static inline struct mtx * 425 bqlock(int qindex) 426 { 427 428 return (struct mtx *)&bqlocks[qindex]; 429 } 430 431 /* 432 * bdirtywakeup: 433 * 434 * Wakeup any bwillwrite() waiters. 435 */ 436 static void 437 bdirtywakeup(void) 438 { 439 mtx_lock(&bdirtylock); 440 if (bdirtywait) { 441 bdirtywait = 0; 442 wakeup(&bdirtywait); 443 } 444 mtx_unlock(&bdirtylock); 445 } 446 447 /* 448 * bdirtysub: 449 * 450 * Decrement the numdirtybuffers count by one and wakeup any 451 * threads blocked in bwillwrite(). 452 */ 453 static void 454 bdirtysub(void) 455 { 456 457 if (atomic_fetchadd_int(&numdirtybuffers, -1) == 458 (lodirtybuffers + hidirtybuffers) / 2) 459 bdirtywakeup(); 460 } 461 462 /* 463 * bdirtyadd: 464 * 465 * Increment the numdirtybuffers count by one and wakeup the buf 466 * daemon if needed. 467 */ 468 static void 469 bdirtyadd(void) 470 { 471 472 /* 473 * Only do the wakeup once as we cross the boundary. The 474 * buf daemon will keep running until the condition clears. 475 */ 476 if (atomic_fetchadd_int(&numdirtybuffers, 1) == 477 (lodirtybuffers + hidirtybuffers) / 2) 478 bd_wakeup(); 479 } 480 481 /* 482 * bufspace_wakeup: 483 * 484 * Called when buffer space is potentially available for recovery. 485 * getnewbuf() will block on this flag when it is unable to free 486 * sufficient buffer space. Buffer space becomes recoverable when 487 * bp's get placed back in the queues. 488 */ 489 static void 490 bufspace_wakeup(void) 491 { 492 493 /* 494 * If someone is waiting for bufspace, wake them up. 495 * 496 * Since needsbuffer is set prior to doing an additional queue 497 * scan it is safe to check for the flag prior to acquiring the 498 * lock. The thread that is preparing to scan again before 499 * blocking would discover the buf we released. 500 */ 501 if (needsbuffer) { 502 rw_rlock(&nblock); 503 if (atomic_cmpset_int(&needsbuffer, 1, 0) == 1) 504 wakeup(__DEVOLATILE(void *, &needsbuffer)); 505 rw_runlock(&nblock); 506 } 507 } 508 509 /* 510 * bufspace_daemonwakeup: 511 * 512 * Wakeup the daemon responsible for freeing clean bufs. 513 */ 514 static void 515 bufspace_daemonwakeup(void) 516 { 517 rw_rlock(&nblock); 518 if (bufspace_request == 0) { 519 bufspace_request = 1; 520 wakeup(&bufspace_request); 521 } 522 rw_runlock(&nblock); 523 } 524 525 /* 526 * bufspace_adjust: 527 * 528 * Adjust the reported bufspace for a KVA managed buffer, possibly 529 * waking any waiters. 530 */ 531 static void 532 bufspace_adjust(struct buf *bp, int bufsize) 533 { 534 long space; 535 int diff; 536 537 KASSERT((bp->b_flags & B_MALLOC) == 0, 538 ("bufspace_adjust: malloc buf %p", bp)); 539 diff = bufsize - bp->b_bufsize; 540 if (diff < 0) { 541 atomic_subtract_long(&bufspace, -diff); 542 bufspace_wakeup(); 543 } else { 544 space = atomic_fetchadd_long(&bufspace, diff); 545 /* Wake up the daemon on the transition. */ 546 if (space < bufspacethresh && space + diff >= bufspacethresh) 547 bufspace_daemonwakeup(); 548 } 549 bp->b_bufsize = bufsize; 550 } 551 552 /* 553 * bufspace_reserve: 554 * 555 * Reserve bufspace before calling allocbuf(). metadata has a 556 * different space limit than data. 557 */ 558 static int 559 bufspace_reserve(int size, bool metadata) 560 { 561 long limit; 562 long space; 563 564 if (metadata) 565 limit = maxbufspace; 566 else 567 limit = hibufspace; 568 do { 569 space = bufspace; 570 if (space + size > limit) 571 return (ENOSPC); 572 } while (atomic_cmpset_long(&bufspace, space, space + size) == 0); 573 574 /* Wake up the daemon on the transition. */ 575 if (space < bufspacethresh && space + size >= bufspacethresh) 576 bufspace_daemonwakeup(); 577 578 return (0); 579 } 580 581 /* 582 * bufspace_release: 583 * 584 * Release reserved bufspace after bufspace_adjust() has consumed it. 585 */ 586 static void 587 bufspace_release(int size) 588 { 589 atomic_subtract_long(&bufspace, size); 590 bufspace_wakeup(); 591 } 592 593 /* 594 * bufspace_wait: 595 * 596 * Wait for bufspace, acting as the buf daemon if a locked vnode is 597 * supplied. needsbuffer must be set in a safe fashion prior to 598 * polling for space. The operation must be re-tried on return. 599 */ 600 static void 601 bufspace_wait(struct vnode *vp, int gbflags, int slpflag, int slptimeo) 602 { 603 struct thread *td; 604 int error, fl, norunbuf; 605 606 if ((gbflags & GB_NOWAIT_BD) != 0) 607 return; 608 609 td = curthread; 610 rw_wlock(&nblock); 611 while (needsbuffer != 0) { 612 if (vp != NULL && vp->v_type != VCHR && 613 (td->td_pflags & TDP_BUFNEED) == 0) { 614 rw_wunlock(&nblock); 615 /* 616 * getblk() is called with a vnode locked, and 617 * some majority of the dirty buffers may as 618 * well belong to the vnode. Flushing the 619 * buffers there would make a progress that 620 * cannot be achieved by the buf_daemon, that 621 * cannot lock the vnode. 622 */ 623 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) | 624 (td->td_pflags & TDP_NORUNNINGBUF); 625 626 /* 627 * Play bufdaemon. The getnewbuf() function 628 * may be called while the thread owns lock 629 * for another dirty buffer for the same 630 * vnode, which makes it impossible to use 631 * VOP_FSYNC() there, due to the buffer lock 632 * recursion. 633 */ 634 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF; 635 fl = buf_flush(vp, flushbufqtarget); 636 td->td_pflags &= norunbuf; 637 rw_wlock(&nblock); 638 if (fl != 0) 639 continue; 640 if (needsbuffer == 0) 641 break; 642 } 643 error = rw_sleep(__DEVOLATILE(void *, &needsbuffer), &nblock, 644 (PRIBIO + 4) | slpflag, "newbuf", slptimeo); 645 if (error != 0) 646 break; 647 } 648 rw_wunlock(&nblock); 649 } 650 651 652 /* 653 * bufspace_daemon: 654 * 655 * buffer space management daemon. Tries to maintain some marginal 656 * amount of free buffer space so that requesting processes neither 657 * block nor work to reclaim buffers. 658 */ 659 static void 660 bufspace_daemon(void) 661 { 662 for (;;) { 663 kproc_suspend_check(bufspacedaemonproc); 664 665 /* 666 * Free buffers from the clean queue until we meet our 667 * targets. 668 * 669 * Theory of operation: The buffer cache is most efficient 670 * when some free buffer headers and space are always 671 * available to getnewbuf(). This daemon attempts to prevent 672 * the excessive blocking and synchronization associated 673 * with shortfall. It goes through three phases according 674 * demand: 675 * 676 * 1) The daemon wakes up voluntarily once per-second 677 * during idle periods when the counters are below 678 * the wakeup thresholds (bufspacethresh, lofreebuffers). 679 * 680 * 2) The daemon wakes up as we cross the thresholds 681 * ahead of any potential blocking. This may bounce 682 * slightly according to the rate of consumption and 683 * release. 684 * 685 * 3) The daemon and consumers are starved for working 686 * clean buffers. This is the 'bufspace' sleep below 687 * which will inefficiently trade bufs with bqrelse 688 * until we return to condition 2. 689 */ 690 while (bufspace > lobufspace || 691 numfreebuffers < hifreebuffers) { 692 if (buf_recycle(false) != 0) { 693 atomic_set_int(&needsbuffer, 1); 694 if (buf_recycle(false) != 0) { 695 rw_wlock(&nblock); 696 if (needsbuffer) 697 rw_sleep(__DEVOLATILE(void *, 698 &needsbuffer), &nblock, 699 PRIBIO|PDROP, "bufspace", 700 hz/10); 701 else 702 rw_wunlock(&nblock); 703 } 704 } 705 maybe_yield(); 706 } 707 708 /* 709 * Re-check our limits under the exclusive nblock. 710 */ 711 rw_wlock(&nblock); 712 if (bufspace < bufspacethresh && 713 numfreebuffers > lofreebuffers) { 714 bufspace_request = 0; 715 rw_sleep(&bufspace_request, &nblock, PRIBIO|PDROP, 716 "-", hz); 717 } else 718 rw_wunlock(&nblock); 719 } 720 } 721 722 static struct kproc_desc bufspace_kp = { 723 "bufspacedaemon", 724 bufspace_daemon, 725 &bufspacedaemonproc 726 }; 727 SYSINIT(bufspacedaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, 728 &bufspace_kp); 729 730 /* 731 * bufmallocadjust: 732 * 733 * Adjust the reported bufspace for a malloc managed buffer, possibly 734 * waking any waiters. 735 */ 736 static void 737 bufmallocadjust(struct buf *bp, int bufsize) 738 { 739 int diff; 740 741 KASSERT((bp->b_flags & B_MALLOC) != 0, 742 ("bufmallocadjust: non-malloc buf %p", bp)); 743 diff = bufsize - bp->b_bufsize; 744 if (diff < 0) 745 atomic_subtract_long(&bufmallocspace, -diff); 746 else 747 atomic_add_long(&bufmallocspace, diff); 748 bp->b_bufsize = bufsize; 749 } 750 751 /* 752 * runningwakeup: 753 * 754 * Wake up processes that are waiting on asynchronous writes to fall 755 * below lorunningspace. 756 */ 757 static void 758 runningwakeup(void) 759 { 760 761 mtx_lock(&rbreqlock); 762 if (runningbufreq) { 763 runningbufreq = 0; 764 wakeup(&runningbufreq); 765 } 766 mtx_unlock(&rbreqlock); 767 } 768 769 /* 770 * runningbufwakeup: 771 * 772 * Decrement the outstanding write count according. 773 */ 774 void 775 runningbufwakeup(struct buf *bp) 776 { 777 long space, bspace; 778 779 bspace = bp->b_runningbufspace; 780 if (bspace == 0) 781 return; 782 space = atomic_fetchadd_long(&runningbufspace, -bspace); 783 KASSERT(space >= bspace, ("runningbufspace underflow %ld %ld", 784 space, bspace)); 785 bp->b_runningbufspace = 0; 786 /* 787 * Only acquire the lock and wakeup on the transition from exceeding 788 * the threshold to falling below it. 789 */ 790 if (space < lorunningspace) 791 return; 792 if (space - bspace > lorunningspace) 793 return; 794 runningwakeup(); 795 } 796 797 /* 798 * waitrunningbufspace() 799 * 800 * runningbufspace is a measure of the amount of I/O currently 801 * running. This routine is used in async-write situations to 802 * prevent creating huge backups of pending writes to a device. 803 * Only asynchronous writes are governed by this function. 804 * 805 * This does NOT turn an async write into a sync write. It waits 806 * for earlier writes to complete and generally returns before the 807 * caller's write has reached the device. 808 */ 809 void 810 waitrunningbufspace(void) 811 { 812 813 mtx_lock(&rbreqlock); 814 while (runningbufspace > hirunningspace) { 815 runningbufreq = 1; 816 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 817 } 818 mtx_unlock(&rbreqlock); 819 } 820 821 822 /* 823 * vfs_buf_test_cache: 824 * 825 * Called when a buffer is extended. This function clears the B_CACHE 826 * bit if the newly extended portion of the buffer does not contain 827 * valid data. 828 */ 829 static __inline void 830 vfs_buf_test_cache(struct buf *bp, vm_ooffset_t foff, vm_offset_t off, 831 vm_offset_t size, vm_page_t m) 832 { 833 834 VM_OBJECT_ASSERT_LOCKED(m->object); 835 if (bp->b_flags & B_CACHE) { 836 int base = (foff + off) & PAGE_MASK; 837 if (vm_page_is_valid(m, base, size) == 0) 838 bp->b_flags &= ~B_CACHE; 839 } 840 } 841 842 /* Wake up the buffer daemon if necessary */ 843 static __inline void 844 bd_wakeup(void) 845 { 846 847 mtx_lock(&bdlock); 848 if (bd_request == 0) { 849 bd_request = 1; 850 wakeup(&bd_request); 851 } 852 mtx_unlock(&bdlock); 853 } 854 855 /* 856 * Adjust the maxbcachbuf tunable. 857 */ 858 static void 859 maxbcachebuf_adjust(void) 860 { 861 int i; 862 863 /* 864 * maxbcachebuf must be a power of 2 >= MAXBSIZE. 865 */ 866 i = 2; 867 while (i * 2 <= maxbcachebuf) 868 i *= 2; 869 maxbcachebuf = i; 870 if (maxbcachebuf < MAXBSIZE) 871 maxbcachebuf = MAXBSIZE; 872 if (maxbcachebuf > MAXPHYS) 873 maxbcachebuf = MAXPHYS; 874 if (bootverbose != 0 && maxbcachebuf != MAXBCACHEBUF) 875 printf("maxbcachebuf=%d\n", maxbcachebuf); 876 } 877 878 /* 879 * bd_speedup - speedup the buffer cache flushing code 880 */ 881 void 882 bd_speedup(void) 883 { 884 int needwake; 885 886 mtx_lock(&bdlock); 887 needwake = 0; 888 if (bd_speedupreq == 0 || bd_request == 0) 889 needwake = 1; 890 bd_speedupreq = 1; 891 bd_request = 1; 892 if (needwake) 893 wakeup(&bd_request); 894 mtx_unlock(&bdlock); 895 } 896 897 #ifndef NSWBUF_MIN 898 #define NSWBUF_MIN 16 899 #endif 900 901 #ifdef __i386__ 902 #define TRANSIENT_DENOM 5 903 #else 904 #define TRANSIENT_DENOM 10 905 #endif 906 907 /* 908 * Calculating buffer cache scaling values and reserve space for buffer 909 * headers. This is called during low level kernel initialization and 910 * may be called more then once. We CANNOT write to the memory area 911 * being reserved at this time. 912 */ 913 caddr_t 914 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 915 { 916 int tuned_nbuf; 917 long maxbuf, maxbuf_sz, buf_sz, biotmap_sz; 918 919 /* 920 * physmem_est is in pages. Convert it to kilobytes (assumes 921 * PAGE_SIZE is >= 1K) 922 */ 923 physmem_est = physmem_est * (PAGE_SIZE / 1024); 924 925 maxbcachebuf_adjust(); 926 /* 927 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 928 * For the first 64MB of ram nominally allocate sufficient buffers to 929 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 930 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing 931 * the buffer cache we limit the eventual kva reservation to 932 * maxbcache bytes. 933 * 934 * factor represents the 1/4 x ram conversion. 935 */ 936 if (nbuf == 0) { 937 int factor = 4 * BKVASIZE / 1024; 938 939 nbuf = 50; 940 if (physmem_est > 4096) 941 nbuf += min((physmem_est - 4096) / factor, 942 65536 / factor); 943 if (physmem_est > 65536) 944 nbuf += min((physmem_est - 65536) * 2 / (factor * 5), 945 32 * 1024 * 1024 / (factor * 5)); 946 947 if (maxbcache && nbuf > maxbcache / BKVASIZE) 948 nbuf = maxbcache / BKVASIZE; 949 tuned_nbuf = 1; 950 } else 951 tuned_nbuf = 0; 952 953 /* XXX Avoid unsigned long overflows later on with maxbufspace. */ 954 maxbuf = (LONG_MAX / 3) / BKVASIZE; 955 if (nbuf > maxbuf) { 956 if (!tuned_nbuf) 957 printf("Warning: nbufs lowered from %d to %ld\n", nbuf, 958 maxbuf); 959 nbuf = maxbuf; 960 } 961 962 /* 963 * Ideal allocation size for the transient bio submap is 10% 964 * of the maximal space buffer map. This roughly corresponds 965 * to the amount of the buffer mapped for typical UFS load. 966 * 967 * Clip the buffer map to reserve space for the transient 968 * BIOs, if its extent is bigger than 90% (80% on i386) of the 969 * maximum buffer map extent on the platform. 970 * 971 * The fall-back to the maxbuf in case of maxbcache unset, 972 * allows to not trim the buffer KVA for the architectures 973 * with ample KVA space. 974 */ 975 if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) { 976 maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE; 977 buf_sz = (long)nbuf * BKVASIZE; 978 if (buf_sz < maxbuf_sz / TRANSIENT_DENOM * 979 (TRANSIENT_DENOM - 1)) { 980 /* 981 * There is more KVA than memory. Do not 982 * adjust buffer map size, and assign the rest 983 * of maxbuf to transient map. 984 */ 985 biotmap_sz = maxbuf_sz - buf_sz; 986 } else { 987 /* 988 * Buffer map spans all KVA we could afford on 989 * this platform. Give 10% (20% on i386) of 990 * the buffer map to the transient bio map. 991 */ 992 biotmap_sz = buf_sz / TRANSIENT_DENOM; 993 buf_sz -= biotmap_sz; 994 } 995 if (biotmap_sz / INT_MAX > MAXPHYS) 996 bio_transient_maxcnt = INT_MAX; 997 else 998 bio_transient_maxcnt = biotmap_sz / MAXPHYS; 999 /* 1000 * Artificially limit to 1024 simultaneous in-flight I/Os 1001 * using the transient mapping. 1002 */ 1003 if (bio_transient_maxcnt > 1024) 1004 bio_transient_maxcnt = 1024; 1005 if (tuned_nbuf) 1006 nbuf = buf_sz / BKVASIZE; 1007 } 1008 1009 /* 1010 * swbufs are used as temporary holders for I/O, such as paging I/O. 1011 * We have no less then 16 and no more then 256. 1012 */ 1013 nswbuf = min(nbuf / 4, 256); 1014 TUNABLE_INT_FETCH("kern.nswbuf", &nswbuf); 1015 if (nswbuf < NSWBUF_MIN) 1016 nswbuf = NSWBUF_MIN; 1017 1018 /* 1019 * Reserve space for the buffer cache buffers 1020 */ 1021 swbuf = (void *)v; 1022 v = (caddr_t)(swbuf + nswbuf); 1023 buf = (void *)v; 1024 v = (caddr_t)(buf + nbuf); 1025 1026 return(v); 1027 } 1028 1029 /* Initialize the buffer subsystem. Called before use of any buffers. */ 1030 void 1031 bufinit(void) 1032 { 1033 struct buf *bp; 1034 int i; 1035 1036 KASSERT(maxbcachebuf >= MAXBSIZE, 1037 ("maxbcachebuf (%d) must be >= MAXBSIZE (%d)\n", maxbcachebuf, 1038 MAXBSIZE)); 1039 mtx_init(&bqlocks[QUEUE_DIRTY], "bufq dirty lock", NULL, MTX_DEF); 1040 mtx_init(&bqlocks[QUEUE_EMPTY], "bufq empty lock", NULL, MTX_DEF); 1041 for (i = QUEUE_CLEAN; i < QUEUE_CLEAN + CLEAN_QUEUES; i++) 1042 mtx_init(&bqlocks[i], "bufq clean lock", NULL, MTX_DEF); 1043 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 1044 rw_init(&nblock, "needsbuffer lock"); 1045 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 1046 mtx_init(&bdirtylock, "dirty buf lock", NULL, MTX_DEF); 1047 1048 /* next, make a null set of free lists */ 1049 for (i = 0; i < BUFFER_QUEUES; i++) 1050 TAILQ_INIT(&bufqueues[i]); 1051 1052 unmapped_buf = (caddr_t)kva_alloc(MAXPHYS); 1053 1054 /* finally, initialize each buffer header and stick on empty q */ 1055 for (i = 0; i < nbuf; i++) { 1056 bp = &buf[i]; 1057 bzero(bp, sizeof *bp); 1058 bp->b_flags = B_INVAL; 1059 bp->b_rcred = NOCRED; 1060 bp->b_wcred = NOCRED; 1061 bp->b_qindex = QUEUE_EMPTY; 1062 bp->b_xflags = 0; 1063 bp->b_data = bp->b_kvabase = unmapped_buf; 1064 LIST_INIT(&bp->b_dep); 1065 BUF_LOCKINIT(bp); 1066 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 1067 #ifdef INVARIANTS 1068 bq_len[QUEUE_EMPTY]++; 1069 #endif 1070 } 1071 1072 /* 1073 * maxbufspace is the absolute maximum amount of buffer space we are 1074 * allowed to reserve in KVM and in real terms. The absolute maximum 1075 * is nominally used by metadata. hibufspace is the nominal maximum 1076 * used by most other requests. The differential is required to 1077 * ensure that metadata deadlocks don't occur. 1078 * 1079 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 1080 * this may result in KVM fragmentation which is not handled optimally 1081 * by the system. XXX This is less true with vmem. We could use 1082 * PAGE_SIZE. 1083 */ 1084 maxbufspace = (long)nbuf * BKVASIZE; 1085 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - maxbcachebuf * 10); 1086 lobufspace = (hibufspace / 20) * 19; /* 95% */ 1087 bufspacethresh = lobufspace + (hibufspace - lobufspace) / 2; 1088 1089 /* 1090 * Note: The 16 MiB upper limit for hirunningspace was chosen 1091 * arbitrarily and may need further tuning. It corresponds to 1092 * 128 outstanding write IO requests (if IO size is 128 KiB), 1093 * which fits with many RAID controllers' tagged queuing limits. 1094 * The lower 1 MiB limit is the historical upper limit for 1095 * hirunningspace. 1096 */ 1097 hirunningspace = lmax(lmin(roundup(hibufspace / 64, maxbcachebuf), 1098 16 * 1024 * 1024), 1024 * 1024); 1099 lorunningspace = roundup((hirunningspace * 2) / 3, maxbcachebuf); 1100 1101 /* 1102 * Limit the amount of malloc memory since it is wired permanently into 1103 * the kernel space. Even though this is accounted for in the buffer 1104 * allocation, we don't want the malloced region to grow uncontrolled. 1105 * The malloc scheme improves memory utilization significantly on 1106 * average (small) directories. 1107 */ 1108 maxbufmallocspace = hibufspace / 20; 1109 1110 /* 1111 * Reduce the chance of a deadlock occurring by limiting the number 1112 * of delayed-write dirty buffers we allow to stack up. 1113 */ 1114 hidirtybuffers = nbuf / 4 + 20; 1115 dirtybufthresh = hidirtybuffers * 9 / 10; 1116 numdirtybuffers = 0; 1117 /* 1118 * To support extreme low-memory systems, make sure hidirtybuffers 1119 * cannot eat up all available buffer space. This occurs when our 1120 * minimum cannot be met. We try to size hidirtybuffers to 3/4 our 1121 * buffer space assuming BKVASIZE'd buffers. 1122 */ 1123 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 1124 hidirtybuffers >>= 1; 1125 } 1126 lodirtybuffers = hidirtybuffers / 2; 1127 1128 /* 1129 * lofreebuffers should be sufficient to avoid stalling waiting on 1130 * buf headers under heavy utilization. The bufs in per-cpu caches 1131 * are counted as free but will be unavailable to threads executing 1132 * on other cpus. 1133 * 1134 * hifreebuffers is the free target for the bufspace daemon. This 1135 * should be set appropriately to limit work per-iteration. 1136 */ 1137 lofreebuffers = MIN((nbuf / 25) + (20 * mp_ncpus), 128 * mp_ncpus); 1138 hifreebuffers = (3 * lofreebuffers) / 2; 1139 numfreebuffers = nbuf; 1140 1141 /* Setup the kva and free list allocators. */ 1142 vmem_set_reclaim(buffer_arena, bufkva_reclaim); 1143 buf_zone = uma_zcache_create("buf free cache", sizeof(struct buf), 1144 NULL, NULL, NULL, NULL, buf_import, buf_release, NULL, 0); 1145 1146 /* 1147 * Size the clean queue according to the amount of buffer space. 1148 * One queue per-256mb up to the max. More queues gives better 1149 * concurrency but less accurate LRU. 1150 */ 1151 clean_queues = MIN(howmany(maxbufspace, 256*1024*1024), CLEAN_QUEUES); 1152 1153 } 1154 1155 #ifdef INVARIANTS 1156 static inline void 1157 vfs_buf_check_mapped(struct buf *bp) 1158 { 1159 1160 KASSERT(bp->b_kvabase != unmapped_buf, 1161 ("mapped buf: b_kvabase was not updated %p", bp)); 1162 KASSERT(bp->b_data != unmapped_buf, 1163 ("mapped buf: b_data was not updated %p", bp)); 1164 KASSERT(bp->b_data < unmapped_buf || bp->b_data >= unmapped_buf + 1165 MAXPHYS, ("b_data + b_offset unmapped %p", bp)); 1166 } 1167 1168 static inline void 1169 vfs_buf_check_unmapped(struct buf *bp) 1170 { 1171 1172 KASSERT(bp->b_data == unmapped_buf, 1173 ("unmapped buf: corrupted b_data %p", bp)); 1174 } 1175 1176 #define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp) 1177 #define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp) 1178 #else 1179 #define BUF_CHECK_MAPPED(bp) do {} while (0) 1180 #define BUF_CHECK_UNMAPPED(bp) do {} while (0) 1181 #endif 1182 1183 static int 1184 isbufbusy(struct buf *bp) 1185 { 1186 if (((bp->b_flags & B_INVAL) == 0 && BUF_ISLOCKED(bp)) || 1187 ((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI)) 1188 return (1); 1189 return (0); 1190 } 1191 1192 /* 1193 * Shutdown the system cleanly to prepare for reboot, halt, or power off. 1194 */ 1195 void 1196 bufshutdown(int show_busybufs) 1197 { 1198 static int first_buf_printf = 1; 1199 struct buf *bp; 1200 int iter, nbusy, pbusy; 1201 #ifndef PREEMPTION 1202 int subiter; 1203 #endif 1204 1205 /* 1206 * Sync filesystems for shutdown 1207 */ 1208 wdog_kern_pat(WD_LASTVAL); 1209 sys_sync(curthread, NULL); 1210 1211 /* 1212 * With soft updates, some buffers that are 1213 * written will be remarked as dirty until other 1214 * buffers are written. 1215 */ 1216 for (iter = pbusy = 0; iter < 20; iter++) { 1217 nbusy = 0; 1218 for (bp = &buf[nbuf]; --bp >= buf; ) 1219 if (isbufbusy(bp)) 1220 nbusy++; 1221 if (nbusy == 0) { 1222 if (first_buf_printf) 1223 printf("All buffers synced."); 1224 break; 1225 } 1226 if (first_buf_printf) { 1227 printf("Syncing disks, buffers remaining... "); 1228 first_buf_printf = 0; 1229 } 1230 printf("%d ", nbusy); 1231 if (nbusy < pbusy) 1232 iter = 0; 1233 pbusy = nbusy; 1234 1235 wdog_kern_pat(WD_LASTVAL); 1236 sys_sync(curthread, NULL); 1237 1238 #ifdef PREEMPTION 1239 /* 1240 * Drop Giant and spin for a while to allow 1241 * interrupt threads to run. 1242 */ 1243 DROP_GIANT(); 1244 DELAY(50000 * iter); 1245 PICKUP_GIANT(); 1246 #else 1247 /* 1248 * Drop Giant and context switch several times to 1249 * allow interrupt threads to run. 1250 */ 1251 DROP_GIANT(); 1252 for (subiter = 0; subiter < 50 * iter; subiter++) { 1253 thread_lock(curthread); 1254 mi_switch(SW_VOL, NULL); 1255 thread_unlock(curthread); 1256 DELAY(1000); 1257 } 1258 PICKUP_GIANT(); 1259 #endif 1260 } 1261 printf("\n"); 1262 /* 1263 * Count only busy local buffers to prevent forcing 1264 * a fsck if we're just a client of a wedged NFS server 1265 */ 1266 nbusy = 0; 1267 for (bp = &buf[nbuf]; --bp >= buf; ) { 1268 if (isbufbusy(bp)) { 1269 #if 0 1270 /* XXX: This is bogus. We should probably have a BO_REMOTE flag instead */ 1271 if (bp->b_dev == NULL) { 1272 TAILQ_REMOVE(&mountlist, 1273 bp->b_vp->v_mount, mnt_list); 1274 continue; 1275 } 1276 #endif 1277 nbusy++; 1278 if (show_busybufs > 0) { 1279 printf( 1280 "%d: buf:%p, vnode:%p, flags:%0x, blkno:%jd, lblkno:%jd, buflock:", 1281 nbusy, bp, bp->b_vp, bp->b_flags, 1282 (intmax_t)bp->b_blkno, 1283 (intmax_t)bp->b_lblkno); 1284 BUF_LOCKPRINTINFO(bp); 1285 if (show_busybufs > 1) 1286 vn_printf(bp->b_vp, 1287 "vnode content: "); 1288 } 1289 } 1290 } 1291 if (nbusy) { 1292 /* 1293 * Failed to sync all blocks. Indicate this and don't 1294 * unmount filesystems (thus forcing an fsck on reboot). 1295 */ 1296 printf("Giving up on %d buffers\n", nbusy); 1297 DELAY(5000000); /* 5 seconds */ 1298 } else { 1299 if (!first_buf_printf) 1300 printf("Final sync complete\n"); 1301 /* 1302 * Unmount filesystems 1303 */ 1304 if (panicstr == NULL) 1305 vfs_unmountall(); 1306 } 1307 swapoff_all(); 1308 DELAY(100000); /* wait for console output to finish */ 1309 } 1310 1311 static void 1312 bpmap_qenter(struct buf *bp) 1313 { 1314 1315 BUF_CHECK_MAPPED(bp); 1316 1317 /* 1318 * bp->b_data is relative to bp->b_offset, but 1319 * bp->b_offset may be offset into the first page. 1320 */ 1321 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data); 1322 pmap_qenter((vm_offset_t)bp->b_data, bp->b_pages, bp->b_npages); 1323 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 1324 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 1325 } 1326 1327 /* 1328 * binsfree: 1329 * 1330 * Insert the buffer into the appropriate free list. 1331 */ 1332 static void 1333 binsfree(struct buf *bp, int qindex) 1334 { 1335 struct mtx *olock, *nlock; 1336 1337 if (qindex != QUEUE_EMPTY) { 1338 BUF_ASSERT_XLOCKED(bp); 1339 } 1340 1341 /* 1342 * Stick to the same clean queue for the lifetime of the buf to 1343 * limit locking below. Otherwise pick ont sequentially. 1344 */ 1345 if (qindex == QUEUE_CLEAN) { 1346 if (bqisclean(bp->b_qindex)) 1347 qindex = bp->b_qindex; 1348 else 1349 qindex = bqcleanq(); 1350 } 1351 1352 /* 1353 * Handle delayed bremfree() processing. 1354 */ 1355 nlock = bqlock(qindex); 1356 if (bp->b_flags & B_REMFREE) { 1357 olock = bqlock(bp->b_qindex); 1358 mtx_lock(olock); 1359 bremfreel(bp); 1360 if (olock != nlock) { 1361 mtx_unlock(olock); 1362 mtx_lock(nlock); 1363 } 1364 } else 1365 mtx_lock(nlock); 1366 1367 if (bp->b_qindex != QUEUE_NONE) 1368 panic("binsfree: free buffer onto another queue???"); 1369 1370 bp->b_qindex = qindex; 1371 if (bp->b_flags & B_AGE) 1372 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1373 else 1374 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1375 #ifdef INVARIANTS 1376 bq_len[bp->b_qindex]++; 1377 #endif 1378 mtx_unlock(nlock); 1379 } 1380 1381 /* 1382 * buf_free: 1383 * 1384 * Free a buffer to the buf zone once it no longer has valid contents. 1385 */ 1386 static void 1387 buf_free(struct buf *bp) 1388 { 1389 1390 if (bp->b_flags & B_REMFREE) 1391 bremfreef(bp); 1392 if (bp->b_vflags & BV_BKGRDINPROG) 1393 panic("losing buffer 1"); 1394 if (bp->b_rcred != NOCRED) { 1395 crfree(bp->b_rcred); 1396 bp->b_rcred = NOCRED; 1397 } 1398 if (bp->b_wcred != NOCRED) { 1399 crfree(bp->b_wcred); 1400 bp->b_wcred = NOCRED; 1401 } 1402 if (!LIST_EMPTY(&bp->b_dep)) 1403 buf_deallocate(bp); 1404 bufkva_free(bp); 1405 BUF_UNLOCK(bp); 1406 uma_zfree(buf_zone, bp); 1407 atomic_add_int(&numfreebuffers, 1); 1408 bufspace_wakeup(); 1409 } 1410 1411 /* 1412 * buf_import: 1413 * 1414 * Import bufs into the uma cache from the buf list. The system still 1415 * expects a static array of bufs and much of the synchronization 1416 * around bufs assumes type stable storage. As a result, UMA is used 1417 * only as a per-cpu cache of bufs still maintained on a global list. 1418 */ 1419 static int 1420 buf_import(void *arg, void **store, int cnt, int flags) 1421 { 1422 struct buf *bp; 1423 int i; 1424 1425 mtx_lock(&bqlocks[QUEUE_EMPTY]); 1426 for (i = 0; i < cnt; i++) { 1427 bp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1428 if (bp == NULL) 1429 break; 1430 bremfreel(bp); 1431 store[i] = bp; 1432 } 1433 mtx_unlock(&bqlocks[QUEUE_EMPTY]); 1434 1435 return (i); 1436 } 1437 1438 /* 1439 * buf_release: 1440 * 1441 * Release bufs from the uma cache back to the buffer queues. 1442 */ 1443 static void 1444 buf_release(void *arg, void **store, int cnt) 1445 { 1446 int i; 1447 1448 for (i = 0; i < cnt; i++) 1449 binsfree(store[i], QUEUE_EMPTY); 1450 } 1451 1452 /* 1453 * buf_alloc: 1454 * 1455 * Allocate an empty buffer header. 1456 */ 1457 static struct buf * 1458 buf_alloc(void) 1459 { 1460 struct buf *bp; 1461 1462 bp = uma_zalloc(buf_zone, M_NOWAIT); 1463 if (bp == NULL) { 1464 bufspace_daemonwakeup(); 1465 atomic_add_int(&numbufallocfails, 1); 1466 return (NULL); 1467 } 1468 1469 /* 1470 * Wake-up the bufspace daemon on transition. 1471 */ 1472 if (atomic_fetchadd_int(&numfreebuffers, -1) == lofreebuffers) 1473 bufspace_daemonwakeup(); 1474 1475 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1476 panic("getnewbuf_empty: Locked buf %p on free queue.", bp); 1477 1478 KASSERT(bp->b_vp == NULL, 1479 ("bp: %p still has vnode %p.", bp, bp->b_vp)); 1480 KASSERT((bp->b_flags & (B_DELWRI | B_NOREUSE)) == 0, 1481 ("invalid buffer %p flags %#x", bp, bp->b_flags)); 1482 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 1483 ("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags)); 1484 KASSERT(bp->b_npages == 0, 1485 ("bp: %p still has %d vm pages\n", bp, bp->b_npages)); 1486 KASSERT(bp->b_kvasize == 0, ("bp: %p still has kva\n", bp)); 1487 KASSERT(bp->b_bufsize == 0, ("bp: %p still has bufspace\n", bp)); 1488 1489 bp->b_flags = 0; 1490 bp->b_ioflags = 0; 1491 bp->b_xflags = 0; 1492 bp->b_vflags = 0; 1493 bp->b_vp = NULL; 1494 bp->b_blkno = bp->b_lblkno = 0; 1495 bp->b_offset = NOOFFSET; 1496 bp->b_iodone = 0; 1497 bp->b_error = 0; 1498 bp->b_resid = 0; 1499 bp->b_bcount = 0; 1500 bp->b_npages = 0; 1501 bp->b_dirtyoff = bp->b_dirtyend = 0; 1502 bp->b_bufobj = NULL; 1503 bp->b_data = bp->b_kvabase = unmapped_buf; 1504 bp->b_fsprivate1 = NULL; 1505 bp->b_fsprivate2 = NULL; 1506 bp->b_fsprivate3 = NULL; 1507 LIST_INIT(&bp->b_dep); 1508 1509 return (bp); 1510 } 1511 1512 /* 1513 * buf_qrecycle: 1514 * 1515 * Free a buffer from the given bufqueue. kva controls whether the 1516 * freed buf must own some kva resources. This is used for 1517 * defragmenting. 1518 */ 1519 static int 1520 buf_qrecycle(int qindex, bool kva) 1521 { 1522 struct buf *bp, *nbp; 1523 1524 if (kva) 1525 atomic_add_int(&bufdefragcnt, 1); 1526 nbp = NULL; 1527 mtx_lock(&bqlocks[qindex]); 1528 nbp = TAILQ_FIRST(&bufqueues[qindex]); 1529 1530 /* 1531 * Run scan, possibly freeing data and/or kva mappings on the fly 1532 * depending. 1533 */ 1534 while ((bp = nbp) != NULL) { 1535 /* 1536 * Calculate next bp (we can only use it if we do not 1537 * release the bqlock). 1538 */ 1539 nbp = TAILQ_NEXT(bp, b_freelist); 1540 1541 /* 1542 * If we are defragging then we need a buffer with 1543 * some kva to reclaim. 1544 */ 1545 if (kva && bp->b_kvasize == 0) 1546 continue; 1547 1548 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1549 continue; 1550 1551 /* 1552 * Skip buffers with background writes in progress. 1553 */ 1554 if ((bp->b_vflags & BV_BKGRDINPROG) != 0) { 1555 BUF_UNLOCK(bp); 1556 continue; 1557 } 1558 1559 KASSERT(bp->b_qindex == qindex, 1560 ("getnewbuf: inconsistent queue %d bp %p", qindex, bp)); 1561 /* 1562 * NOTE: nbp is now entirely invalid. We can only restart 1563 * the scan from this point on. 1564 */ 1565 bremfreel(bp); 1566 mtx_unlock(&bqlocks[qindex]); 1567 1568 /* 1569 * Requeue the background write buffer with error and 1570 * restart the scan. 1571 */ 1572 if ((bp->b_vflags & BV_BKGRDERR) != 0) { 1573 bqrelse(bp); 1574 mtx_lock(&bqlocks[qindex]); 1575 nbp = TAILQ_FIRST(&bufqueues[qindex]); 1576 continue; 1577 } 1578 bp->b_flags |= B_INVAL; 1579 brelse(bp); 1580 return (0); 1581 } 1582 mtx_unlock(&bqlocks[qindex]); 1583 1584 return (ENOBUFS); 1585 } 1586 1587 /* 1588 * buf_recycle: 1589 * 1590 * Iterate through all clean queues until we find a buf to recycle or 1591 * exhaust the search. 1592 */ 1593 static int 1594 buf_recycle(bool kva) 1595 { 1596 int qindex, first_qindex; 1597 1598 qindex = first_qindex = bqcleanq(); 1599 do { 1600 if (buf_qrecycle(qindex, kva) == 0) 1601 return (0); 1602 if (++qindex == QUEUE_CLEAN + clean_queues) 1603 qindex = QUEUE_CLEAN; 1604 } while (qindex != first_qindex); 1605 1606 return (ENOBUFS); 1607 } 1608 1609 /* 1610 * buf_scan: 1611 * 1612 * Scan the clean queues looking for a buffer to recycle. needsbuffer 1613 * is set on failure so that the caller may optionally bufspace_wait() 1614 * in a race-free fashion. 1615 */ 1616 static int 1617 buf_scan(bool defrag) 1618 { 1619 int error; 1620 1621 /* 1622 * To avoid heavy synchronization and wakeup races we set 1623 * needsbuffer and re-poll before failing. This ensures that 1624 * no frees can be missed between an unsuccessful poll and 1625 * going to sleep in a synchronized fashion. 1626 */ 1627 if ((error = buf_recycle(defrag)) != 0) { 1628 atomic_set_int(&needsbuffer, 1); 1629 bufspace_daemonwakeup(); 1630 error = buf_recycle(defrag); 1631 } 1632 if (error == 0) 1633 atomic_add_int(&getnewbufrestarts, 1); 1634 return (error); 1635 } 1636 1637 /* 1638 * bremfree: 1639 * 1640 * Mark the buffer for removal from the appropriate free list. 1641 * 1642 */ 1643 void 1644 bremfree(struct buf *bp) 1645 { 1646 1647 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1648 KASSERT((bp->b_flags & B_REMFREE) == 0, 1649 ("bremfree: buffer %p already marked for delayed removal.", bp)); 1650 KASSERT(bp->b_qindex != QUEUE_NONE, 1651 ("bremfree: buffer %p not on a queue.", bp)); 1652 BUF_ASSERT_XLOCKED(bp); 1653 1654 bp->b_flags |= B_REMFREE; 1655 } 1656 1657 /* 1658 * bremfreef: 1659 * 1660 * Force an immediate removal from a free list. Used only in nfs when 1661 * it abuses the b_freelist pointer. 1662 */ 1663 void 1664 bremfreef(struct buf *bp) 1665 { 1666 struct mtx *qlock; 1667 1668 qlock = bqlock(bp->b_qindex); 1669 mtx_lock(qlock); 1670 bremfreel(bp); 1671 mtx_unlock(qlock); 1672 } 1673 1674 /* 1675 * bremfreel: 1676 * 1677 * Removes a buffer from the free list, must be called with the 1678 * correct qlock held. 1679 */ 1680 static void 1681 bremfreel(struct buf *bp) 1682 { 1683 1684 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X", 1685 bp, bp->b_vp, bp->b_flags); 1686 KASSERT(bp->b_qindex != QUEUE_NONE, 1687 ("bremfreel: buffer %p not on a queue.", bp)); 1688 if (bp->b_qindex != QUEUE_EMPTY) { 1689 BUF_ASSERT_XLOCKED(bp); 1690 } 1691 mtx_assert(bqlock(bp->b_qindex), MA_OWNED); 1692 1693 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 1694 #ifdef INVARIANTS 1695 KASSERT(bq_len[bp->b_qindex] >= 1, ("queue %d underflow", 1696 bp->b_qindex)); 1697 bq_len[bp->b_qindex]--; 1698 #endif 1699 bp->b_qindex = QUEUE_NONE; 1700 bp->b_flags &= ~B_REMFREE; 1701 } 1702 1703 /* 1704 * bufkva_free: 1705 * 1706 * Free the kva allocation for a buffer. 1707 * 1708 */ 1709 static void 1710 bufkva_free(struct buf *bp) 1711 { 1712 1713 #ifdef INVARIANTS 1714 if (bp->b_kvasize == 0) { 1715 KASSERT(bp->b_kvabase == unmapped_buf && 1716 bp->b_data == unmapped_buf, 1717 ("Leaked KVA space on %p", bp)); 1718 } else if (buf_mapped(bp)) 1719 BUF_CHECK_MAPPED(bp); 1720 else 1721 BUF_CHECK_UNMAPPED(bp); 1722 #endif 1723 if (bp->b_kvasize == 0) 1724 return; 1725 1726 vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, bp->b_kvasize); 1727 atomic_subtract_long(&bufkvaspace, bp->b_kvasize); 1728 atomic_add_int(&buffreekvacnt, 1); 1729 bp->b_data = bp->b_kvabase = unmapped_buf; 1730 bp->b_kvasize = 0; 1731 } 1732 1733 /* 1734 * bufkva_alloc: 1735 * 1736 * Allocate the buffer KVA and set b_kvasize and b_kvabase. 1737 */ 1738 static int 1739 bufkva_alloc(struct buf *bp, int maxsize, int gbflags) 1740 { 1741 vm_offset_t addr; 1742 int error; 1743 1744 KASSERT((gbflags & GB_UNMAPPED) == 0 || (gbflags & GB_KVAALLOC) != 0, 1745 ("Invalid gbflags 0x%x in %s", gbflags, __func__)); 1746 1747 bufkva_free(bp); 1748 1749 addr = 0; 1750 error = vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr); 1751 if (error != 0) { 1752 /* 1753 * Buffer map is too fragmented. Request the caller 1754 * to defragment the map. 1755 */ 1756 return (error); 1757 } 1758 bp->b_kvabase = (caddr_t)addr; 1759 bp->b_kvasize = maxsize; 1760 atomic_add_long(&bufkvaspace, bp->b_kvasize); 1761 if ((gbflags & GB_UNMAPPED) != 0) { 1762 bp->b_data = unmapped_buf; 1763 BUF_CHECK_UNMAPPED(bp); 1764 } else { 1765 bp->b_data = bp->b_kvabase; 1766 BUF_CHECK_MAPPED(bp); 1767 } 1768 return (0); 1769 } 1770 1771 /* 1772 * bufkva_reclaim: 1773 * 1774 * Reclaim buffer kva by freeing buffers holding kva. This is a vmem 1775 * callback that fires to avoid returning failure. 1776 */ 1777 static void 1778 bufkva_reclaim(vmem_t *vmem, int flags) 1779 { 1780 int i; 1781 1782 for (i = 0; i < 5; i++) 1783 if (buf_scan(true) != 0) 1784 break; 1785 return; 1786 } 1787 1788 /* 1789 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 1790 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 1791 * the buffer is valid and we do not have to do anything. 1792 */ 1793 static void 1794 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, int cnt, 1795 struct ucred * cred, int flags, void (*ckhashfunc)(struct buf *)) 1796 { 1797 struct buf *rabp; 1798 int i; 1799 1800 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 1801 if (inmem(vp, *rablkno)) 1802 continue; 1803 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 1804 if ((rabp->b_flags & B_CACHE) != 0) { 1805 brelse(rabp); 1806 continue; 1807 } 1808 if (!TD_IS_IDLETHREAD(curthread)) { 1809 #ifdef RACCT 1810 if (racct_enable) { 1811 PROC_LOCK(curproc); 1812 racct_add_buf(curproc, rabp, 0); 1813 PROC_UNLOCK(curproc); 1814 } 1815 #endif /* RACCT */ 1816 curthread->td_ru.ru_inblock++; 1817 } 1818 rabp->b_flags |= B_ASYNC; 1819 rabp->b_flags &= ~B_INVAL; 1820 if ((flags & GB_CKHASH) != 0) { 1821 rabp->b_flags |= B_CKHASH; 1822 rabp->b_ckhashcalc = ckhashfunc; 1823 } 1824 rabp->b_ioflags &= ~BIO_ERROR; 1825 rabp->b_iocmd = BIO_READ; 1826 if (rabp->b_rcred == NOCRED && cred != NOCRED) 1827 rabp->b_rcred = crhold(cred); 1828 vfs_busy_pages(rabp, 0); 1829 BUF_KERNPROC(rabp); 1830 rabp->b_iooffset = dbtob(rabp->b_blkno); 1831 bstrategy(rabp); 1832 } 1833 } 1834 1835 /* 1836 * Entry point for bread() and breadn() via #defines in sys/buf.h. 1837 * 1838 * Get a buffer with the specified data. Look in the cache first. We 1839 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 1840 * is set, the buffer is valid and we do not have to do anything, see 1841 * getblk(). Also starts asynchronous I/O on read-ahead blocks. 1842 * 1843 * Always return a NULL buffer pointer (in bpp) when returning an error. 1844 */ 1845 int 1846 breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno, 1847 int *rabsize, int cnt, struct ucred *cred, int flags, 1848 void (*ckhashfunc)(struct buf *), struct buf **bpp) 1849 { 1850 struct buf *bp; 1851 int readwait, rv; 1852 1853 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 1854 /* 1855 * Can only return NULL if GB_LOCK_NOWAIT flag is specified. 1856 */ 1857 *bpp = bp = getblk(vp, blkno, size, 0, 0, flags); 1858 if (bp == NULL) 1859 return (EBUSY); 1860 1861 /* 1862 * If not found in cache, do some I/O 1863 */ 1864 readwait = 0; 1865 if ((bp->b_flags & B_CACHE) == 0) { 1866 if (!TD_IS_IDLETHREAD(curthread)) { 1867 #ifdef RACCT 1868 if (racct_enable) { 1869 PROC_LOCK(curproc); 1870 racct_add_buf(curproc, bp, 0); 1871 PROC_UNLOCK(curproc); 1872 } 1873 #endif /* RACCT */ 1874 curthread->td_ru.ru_inblock++; 1875 } 1876 bp->b_iocmd = BIO_READ; 1877 bp->b_flags &= ~B_INVAL; 1878 if ((flags & GB_CKHASH) != 0) { 1879 bp->b_flags |= B_CKHASH; 1880 bp->b_ckhashcalc = ckhashfunc; 1881 } 1882 bp->b_ioflags &= ~BIO_ERROR; 1883 if (bp->b_rcred == NOCRED && cred != NOCRED) 1884 bp->b_rcred = crhold(cred); 1885 vfs_busy_pages(bp, 0); 1886 bp->b_iooffset = dbtob(bp->b_blkno); 1887 bstrategy(bp); 1888 ++readwait; 1889 } 1890 1891 /* 1892 * Attempt to initiate asynchronous I/O on read-ahead blocks. 1893 */ 1894 breada(vp, rablkno, rabsize, cnt, cred, flags, ckhashfunc); 1895 1896 rv = 0; 1897 if (readwait) { 1898 rv = bufwait(bp); 1899 if (rv != 0) { 1900 brelse(bp); 1901 *bpp = NULL; 1902 } 1903 } 1904 return (rv); 1905 } 1906 1907 /* 1908 * Write, release buffer on completion. (Done by iodone 1909 * if async). Do not bother writing anything if the buffer 1910 * is invalid. 1911 * 1912 * Note that we set B_CACHE here, indicating that buffer is 1913 * fully valid and thus cacheable. This is true even of NFS 1914 * now so we set it generally. This could be set either here 1915 * or in biodone() since the I/O is synchronous. We put it 1916 * here. 1917 */ 1918 int 1919 bufwrite(struct buf *bp) 1920 { 1921 int oldflags; 1922 struct vnode *vp; 1923 long space; 1924 int vp_md; 1925 1926 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1927 if ((bp->b_bufobj->bo_flag & BO_DEAD) != 0) { 1928 bp->b_flags |= B_INVAL | B_RELBUF; 1929 bp->b_flags &= ~B_CACHE; 1930 brelse(bp); 1931 return (ENXIO); 1932 } 1933 if (bp->b_flags & B_INVAL) { 1934 brelse(bp); 1935 return (0); 1936 } 1937 1938 if (bp->b_flags & B_BARRIER) 1939 barrierwrites++; 1940 1941 oldflags = bp->b_flags; 1942 1943 BUF_ASSERT_HELD(bp); 1944 1945 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 1946 ("FFS background buffer should not get here %p", bp)); 1947 1948 vp = bp->b_vp; 1949 if (vp) 1950 vp_md = vp->v_vflag & VV_MD; 1951 else 1952 vp_md = 0; 1953 1954 /* 1955 * Mark the buffer clean. Increment the bufobj write count 1956 * before bundirty() call, to prevent other thread from seeing 1957 * empty dirty list and zero counter for writes in progress, 1958 * falsely indicating that the bufobj is clean. 1959 */ 1960 bufobj_wref(bp->b_bufobj); 1961 bundirty(bp); 1962 1963 bp->b_flags &= ~B_DONE; 1964 bp->b_ioflags &= ~BIO_ERROR; 1965 bp->b_flags |= B_CACHE; 1966 bp->b_iocmd = BIO_WRITE; 1967 1968 vfs_busy_pages(bp, 1); 1969 1970 /* 1971 * Normal bwrites pipeline writes 1972 */ 1973 bp->b_runningbufspace = bp->b_bufsize; 1974 space = atomic_fetchadd_long(&runningbufspace, bp->b_runningbufspace); 1975 1976 if (!TD_IS_IDLETHREAD(curthread)) { 1977 #ifdef RACCT 1978 if (racct_enable) { 1979 PROC_LOCK(curproc); 1980 racct_add_buf(curproc, bp, 1); 1981 PROC_UNLOCK(curproc); 1982 } 1983 #endif /* RACCT */ 1984 curthread->td_ru.ru_oublock++; 1985 } 1986 if (oldflags & B_ASYNC) 1987 BUF_KERNPROC(bp); 1988 bp->b_iooffset = dbtob(bp->b_blkno); 1989 buf_track(bp, __func__); 1990 bstrategy(bp); 1991 1992 if ((oldflags & B_ASYNC) == 0) { 1993 int rtval = bufwait(bp); 1994 brelse(bp); 1995 return (rtval); 1996 } else if (space > hirunningspace) { 1997 /* 1998 * don't allow the async write to saturate the I/O 1999 * system. We will not deadlock here because 2000 * we are blocking waiting for I/O that is already in-progress 2001 * to complete. We do not block here if it is the update 2002 * or syncer daemon trying to clean up as that can lead 2003 * to deadlock. 2004 */ 2005 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 2006 waitrunningbufspace(); 2007 } 2008 2009 return (0); 2010 } 2011 2012 void 2013 bufbdflush(struct bufobj *bo, struct buf *bp) 2014 { 2015 struct buf *nbp; 2016 2017 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 2018 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 2019 altbufferflushes++; 2020 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 2021 BO_LOCK(bo); 2022 /* 2023 * Try to find a buffer to flush. 2024 */ 2025 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 2026 if ((nbp->b_vflags & BV_BKGRDINPROG) || 2027 BUF_LOCK(nbp, 2028 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 2029 continue; 2030 if (bp == nbp) 2031 panic("bdwrite: found ourselves"); 2032 BO_UNLOCK(bo); 2033 /* Don't countdeps with the bo lock held. */ 2034 if (buf_countdeps(nbp, 0)) { 2035 BO_LOCK(bo); 2036 BUF_UNLOCK(nbp); 2037 continue; 2038 } 2039 if (nbp->b_flags & B_CLUSTEROK) { 2040 vfs_bio_awrite(nbp); 2041 } else { 2042 bremfree(nbp); 2043 bawrite(nbp); 2044 } 2045 dirtybufferflushes++; 2046 break; 2047 } 2048 if (nbp == NULL) 2049 BO_UNLOCK(bo); 2050 } 2051 } 2052 2053 /* 2054 * Delayed write. (Buffer is marked dirty). Do not bother writing 2055 * anything if the buffer is marked invalid. 2056 * 2057 * Note that since the buffer must be completely valid, we can safely 2058 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 2059 * biodone() in order to prevent getblk from writing the buffer 2060 * out synchronously. 2061 */ 2062 void 2063 bdwrite(struct buf *bp) 2064 { 2065 struct thread *td = curthread; 2066 struct vnode *vp; 2067 struct bufobj *bo; 2068 2069 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2070 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2071 KASSERT((bp->b_flags & B_BARRIER) == 0, 2072 ("Barrier request in delayed write %p", bp)); 2073 BUF_ASSERT_HELD(bp); 2074 2075 if (bp->b_flags & B_INVAL) { 2076 brelse(bp); 2077 return; 2078 } 2079 2080 /* 2081 * If we have too many dirty buffers, don't create any more. 2082 * If we are wildly over our limit, then force a complete 2083 * cleanup. Otherwise, just keep the situation from getting 2084 * out of control. Note that we have to avoid a recursive 2085 * disaster and not try to clean up after our own cleanup! 2086 */ 2087 vp = bp->b_vp; 2088 bo = bp->b_bufobj; 2089 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 2090 td->td_pflags |= TDP_INBDFLUSH; 2091 BO_BDFLUSH(bo, bp); 2092 td->td_pflags &= ~TDP_INBDFLUSH; 2093 } else 2094 recursiveflushes++; 2095 2096 bdirty(bp); 2097 /* 2098 * Set B_CACHE, indicating that the buffer is fully valid. This is 2099 * true even of NFS now. 2100 */ 2101 bp->b_flags |= B_CACHE; 2102 2103 /* 2104 * This bmap keeps the system from needing to do the bmap later, 2105 * perhaps when the system is attempting to do a sync. Since it 2106 * is likely that the indirect block -- or whatever other datastructure 2107 * that the filesystem needs is still in memory now, it is a good 2108 * thing to do this. Note also, that if the pageout daemon is 2109 * requesting a sync -- there might not be enough memory to do 2110 * the bmap then... So, this is important to do. 2111 */ 2112 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 2113 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 2114 } 2115 2116 buf_track(bp, __func__); 2117 2118 /* 2119 * Set the *dirty* buffer range based upon the VM system dirty 2120 * pages. 2121 * 2122 * Mark the buffer pages as clean. We need to do this here to 2123 * satisfy the vnode_pager and the pageout daemon, so that it 2124 * thinks that the pages have been "cleaned". Note that since 2125 * the pages are in a delayed write buffer -- the VFS layer 2126 * "will" see that the pages get written out on the next sync, 2127 * or perhaps the cluster will be completed. 2128 */ 2129 vfs_clean_pages_dirty_buf(bp); 2130 bqrelse(bp); 2131 2132 /* 2133 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 2134 * due to the softdep code. 2135 */ 2136 } 2137 2138 /* 2139 * bdirty: 2140 * 2141 * Turn buffer into delayed write request. We must clear BIO_READ and 2142 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 2143 * itself to properly update it in the dirty/clean lists. We mark it 2144 * B_DONE to ensure that any asynchronization of the buffer properly 2145 * clears B_DONE ( else a panic will occur later ). 2146 * 2147 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 2148 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 2149 * should only be called if the buffer is known-good. 2150 * 2151 * Since the buffer is not on a queue, we do not update the numfreebuffers 2152 * count. 2153 * 2154 * The buffer must be on QUEUE_NONE. 2155 */ 2156 void 2157 bdirty(struct buf *bp) 2158 { 2159 2160 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 2161 bp, bp->b_vp, bp->b_flags); 2162 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2163 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 2164 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 2165 BUF_ASSERT_HELD(bp); 2166 bp->b_flags &= ~(B_RELBUF); 2167 bp->b_iocmd = BIO_WRITE; 2168 2169 if ((bp->b_flags & B_DELWRI) == 0) { 2170 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 2171 reassignbuf(bp); 2172 bdirtyadd(); 2173 } 2174 } 2175 2176 /* 2177 * bundirty: 2178 * 2179 * Clear B_DELWRI for buffer. 2180 * 2181 * Since the buffer is not on a queue, we do not update the numfreebuffers 2182 * count. 2183 * 2184 * The buffer must be on QUEUE_NONE. 2185 */ 2186 2187 void 2188 bundirty(struct buf *bp) 2189 { 2190 2191 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2192 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 2193 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 2194 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 2195 BUF_ASSERT_HELD(bp); 2196 2197 if (bp->b_flags & B_DELWRI) { 2198 bp->b_flags &= ~B_DELWRI; 2199 reassignbuf(bp); 2200 bdirtysub(); 2201 } 2202 /* 2203 * Since it is now being written, we can clear its deferred write flag. 2204 */ 2205 bp->b_flags &= ~B_DEFERRED; 2206 } 2207 2208 /* 2209 * bawrite: 2210 * 2211 * Asynchronous write. Start output on a buffer, but do not wait for 2212 * it to complete. The buffer is released when the output completes. 2213 * 2214 * bwrite() ( or the VOP routine anyway ) is responsible for handling 2215 * B_INVAL buffers. Not us. 2216 */ 2217 void 2218 bawrite(struct buf *bp) 2219 { 2220 2221 bp->b_flags |= B_ASYNC; 2222 (void) bwrite(bp); 2223 } 2224 2225 /* 2226 * babarrierwrite: 2227 * 2228 * Asynchronous barrier write. Start output on a buffer, but do not 2229 * wait for it to complete. Place a write barrier after this write so 2230 * that this buffer and all buffers written before it are committed to 2231 * the disk before any buffers written after this write are committed 2232 * to the disk. The buffer is released when the output completes. 2233 */ 2234 void 2235 babarrierwrite(struct buf *bp) 2236 { 2237 2238 bp->b_flags |= B_ASYNC | B_BARRIER; 2239 (void) bwrite(bp); 2240 } 2241 2242 /* 2243 * bbarrierwrite: 2244 * 2245 * Synchronous barrier write. Start output on a buffer and wait for 2246 * it to complete. Place a write barrier after this write so that 2247 * this buffer and all buffers written before it are committed to 2248 * the disk before any buffers written after this write are committed 2249 * to the disk. The buffer is released when the output completes. 2250 */ 2251 int 2252 bbarrierwrite(struct buf *bp) 2253 { 2254 2255 bp->b_flags |= B_BARRIER; 2256 return (bwrite(bp)); 2257 } 2258 2259 /* 2260 * bwillwrite: 2261 * 2262 * Called prior to the locking of any vnodes when we are expecting to 2263 * write. We do not want to starve the buffer cache with too many 2264 * dirty buffers so we block here. By blocking prior to the locking 2265 * of any vnodes we attempt to avoid the situation where a locked vnode 2266 * prevents the various system daemons from flushing related buffers. 2267 */ 2268 void 2269 bwillwrite(void) 2270 { 2271 2272 if (numdirtybuffers >= hidirtybuffers) { 2273 mtx_lock(&bdirtylock); 2274 while (numdirtybuffers >= hidirtybuffers) { 2275 bdirtywait = 1; 2276 msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4), 2277 "flswai", 0); 2278 } 2279 mtx_unlock(&bdirtylock); 2280 } 2281 } 2282 2283 /* 2284 * Return true if we have too many dirty buffers. 2285 */ 2286 int 2287 buf_dirty_count_severe(void) 2288 { 2289 2290 return(numdirtybuffers >= hidirtybuffers); 2291 } 2292 2293 /* 2294 * brelse: 2295 * 2296 * Release a busy buffer and, if requested, free its resources. The 2297 * buffer will be stashed in the appropriate bufqueue[] allowing it 2298 * to be accessed later as a cache entity or reused for other purposes. 2299 */ 2300 void 2301 brelse(struct buf *bp) 2302 { 2303 int qindex; 2304 2305 /* 2306 * Many functions erroneously call brelse with a NULL bp under rare 2307 * error conditions. Simply return when called with a NULL bp. 2308 */ 2309 if (bp == NULL) 2310 return; 2311 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 2312 bp, bp->b_vp, bp->b_flags); 2313 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 2314 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 2315 KASSERT((bp->b_flags & B_VMIO) != 0 || (bp->b_flags & B_NOREUSE) == 0, 2316 ("brelse: non-VMIO buffer marked NOREUSE")); 2317 2318 if (BUF_LOCKRECURSED(bp)) { 2319 /* 2320 * Do not process, in particular, do not handle the 2321 * B_INVAL/B_RELBUF and do not release to free list. 2322 */ 2323 BUF_UNLOCK(bp); 2324 return; 2325 } 2326 2327 if (bp->b_flags & B_MANAGED) { 2328 bqrelse(bp); 2329 return; 2330 } 2331 2332 if ((bp->b_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) { 2333 BO_LOCK(bp->b_bufobj); 2334 bp->b_vflags &= ~BV_BKGRDERR; 2335 BO_UNLOCK(bp->b_bufobj); 2336 bdirty(bp); 2337 } 2338 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 2339 (bp->b_error != ENXIO || !LIST_EMPTY(&bp->b_dep)) && 2340 !(bp->b_flags & B_INVAL)) { 2341 /* 2342 * Failed write, redirty. All errors except ENXIO (which 2343 * means the device is gone) are expected to be potentially 2344 * transient - underlying media might work if tried again 2345 * after EIO, and memory might be available after an ENOMEM. 2346 * 2347 * Do this also for buffers that failed with ENXIO, but have 2348 * non-empty dependencies - the soft updates code might need 2349 * to access the buffer to untangle them. 2350 * 2351 * Must clear BIO_ERROR to prevent pages from being scrapped. 2352 */ 2353 bp->b_ioflags &= ~BIO_ERROR; 2354 bdirty(bp); 2355 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 2356 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 2357 /* 2358 * Either a failed read I/O, or we were asked to free or not 2359 * cache the buffer, or we failed to write to a device that's 2360 * no longer present. 2361 */ 2362 bp->b_flags |= B_INVAL; 2363 if (!LIST_EMPTY(&bp->b_dep)) 2364 buf_deallocate(bp); 2365 if (bp->b_flags & B_DELWRI) 2366 bdirtysub(); 2367 bp->b_flags &= ~(B_DELWRI | B_CACHE); 2368 if ((bp->b_flags & B_VMIO) == 0) { 2369 allocbuf(bp, 0); 2370 if (bp->b_vp) 2371 brelvp(bp); 2372 } 2373 } 2374 2375 /* 2376 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_truncate() 2377 * is called with B_DELWRI set, the underlying pages may wind up 2378 * getting freed causing a previous write (bdwrite()) to get 'lost' 2379 * because pages associated with a B_DELWRI bp are marked clean. 2380 * 2381 * We still allow the B_INVAL case to call vfs_vmio_truncate(), even 2382 * if B_DELWRI is set. 2383 */ 2384 if (bp->b_flags & B_DELWRI) 2385 bp->b_flags &= ~B_RELBUF; 2386 2387 /* 2388 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 2389 * constituted, not even NFS buffers now. Two flags effect this. If 2390 * B_INVAL, the struct buf is invalidated but the VM object is kept 2391 * around ( i.e. so it is trivial to reconstitute the buffer later ). 2392 * 2393 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 2394 * invalidated. BIO_ERROR cannot be set for a failed write unless the 2395 * buffer is also B_INVAL because it hits the re-dirtying code above. 2396 * 2397 * Normally we can do this whether a buffer is B_DELWRI or not. If 2398 * the buffer is an NFS buffer, it is tracking piecemeal writes or 2399 * the commit state and we cannot afford to lose the buffer. If the 2400 * buffer has a background write in progress, we need to keep it 2401 * around to prevent it from being reconstituted and starting a second 2402 * background write. 2403 */ 2404 if ((bp->b_flags & B_VMIO) && (bp->b_flags & B_NOCACHE || 2405 (bp->b_ioflags & BIO_ERROR && bp->b_iocmd == BIO_READ)) && 2406 !(bp->b_vp->v_mount != NULL && 2407 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 2408 !vn_isdisk(bp->b_vp, NULL) && (bp->b_flags & B_DELWRI))) { 2409 vfs_vmio_invalidate(bp); 2410 allocbuf(bp, 0); 2411 } 2412 2413 if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0 || 2414 (bp->b_flags & (B_DELWRI | B_NOREUSE)) == B_NOREUSE) { 2415 allocbuf(bp, 0); 2416 bp->b_flags &= ~B_NOREUSE; 2417 if (bp->b_vp != NULL) 2418 brelvp(bp); 2419 } 2420 2421 /* 2422 * If the buffer has junk contents signal it and eventually 2423 * clean up B_DELWRI and diassociate the vnode so that gbincore() 2424 * doesn't find it. 2425 */ 2426 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 2427 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 2428 bp->b_flags |= B_INVAL; 2429 if (bp->b_flags & B_INVAL) { 2430 if (bp->b_flags & B_DELWRI) 2431 bundirty(bp); 2432 if (bp->b_vp) 2433 brelvp(bp); 2434 } 2435 2436 buf_track(bp, __func__); 2437 2438 /* buffers with no memory */ 2439 if (bp->b_bufsize == 0) { 2440 buf_free(bp); 2441 return; 2442 } 2443 /* buffers with junk contents */ 2444 if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 2445 (bp->b_ioflags & BIO_ERROR)) { 2446 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 2447 if (bp->b_vflags & BV_BKGRDINPROG) 2448 panic("losing buffer 2"); 2449 qindex = QUEUE_CLEAN; 2450 bp->b_flags |= B_AGE; 2451 /* remaining buffers */ 2452 } else if (bp->b_flags & B_DELWRI) 2453 qindex = QUEUE_DIRTY; 2454 else 2455 qindex = QUEUE_CLEAN; 2456 2457 binsfree(bp, qindex); 2458 2459 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 2460 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 2461 panic("brelse: not dirty"); 2462 /* unlock */ 2463 BUF_UNLOCK(bp); 2464 if (qindex == QUEUE_CLEAN) 2465 bufspace_wakeup(); 2466 } 2467 2468 /* 2469 * Release a buffer back to the appropriate queue but do not try to free 2470 * it. The buffer is expected to be used again soon. 2471 * 2472 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 2473 * biodone() to requeue an async I/O on completion. It is also used when 2474 * known good buffers need to be requeued but we think we may need the data 2475 * again soon. 2476 * 2477 * XXX we should be able to leave the B_RELBUF hint set on completion. 2478 */ 2479 void 2480 bqrelse(struct buf *bp) 2481 { 2482 int qindex; 2483 2484 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 2485 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 2486 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 2487 2488 qindex = QUEUE_NONE; 2489 if (BUF_LOCKRECURSED(bp)) { 2490 /* do not release to free list */ 2491 BUF_UNLOCK(bp); 2492 return; 2493 } 2494 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 2495 2496 if (bp->b_flags & B_MANAGED) { 2497 if (bp->b_flags & B_REMFREE) 2498 bremfreef(bp); 2499 goto out; 2500 } 2501 2502 /* buffers with stale but valid contents */ 2503 if ((bp->b_flags & B_DELWRI) != 0 || (bp->b_vflags & (BV_BKGRDINPROG | 2504 BV_BKGRDERR)) == BV_BKGRDERR) { 2505 BO_LOCK(bp->b_bufobj); 2506 bp->b_vflags &= ~BV_BKGRDERR; 2507 BO_UNLOCK(bp->b_bufobj); 2508 qindex = QUEUE_DIRTY; 2509 } else { 2510 if ((bp->b_flags & B_DELWRI) == 0 && 2511 (bp->b_xflags & BX_VNDIRTY)) 2512 panic("bqrelse: not dirty"); 2513 if ((bp->b_flags & B_NOREUSE) != 0) { 2514 brelse(bp); 2515 return; 2516 } 2517 qindex = QUEUE_CLEAN; 2518 } 2519 binsfree(bp, qindex); 2520 2521 out: 2522 buf_track(bp, __func__); 2523 /* unlock */ 2524 BUF_UNLOCK(bp); 2525 if (qindex == QUEUE_CLEAN) 2526 bufspace_wakeup(); 2527 } 2528 2529 /* 2530 * Complete I/O to a VMIO backed page. Validate the pages as appropriate, 2531 * restore bogus pages. 2532 */ 2533 static void 2534 vfs_vmio_iodone(struct buf *bp) 2535 { 2536 vm_ooffset_t foff; 2537 vm_page_t m; 2538 vm_object_t obj; 2539 struct vnode *vp; 2540 int i, iosize, resid; 2541 bool bogus; 2542 2543 obj = bp->b_bufobj->bo_object; 2544 KASSERT(obj->paging_in_progress >= bp->b_npages, 2545 ("vfs_vmio_iodone: paging in progress(%d) < b_npages(%d)", 2546 obj->paging_in_progress, bp->b_npages)); 2547 2548 vp = bp->b_vp; 2549 KASSERT(vp->v_holdcnt > 0, 2550 ("vfs_vmio_iodone: vnode %p has zero hold count", vp)); 2551 KASSERT(vp->v_object != NULL, 2552 ("vfs_vmio_iodone: vnode %p has no vm_object", vp)); 2553 2554 foff = bp->b_offset; 2555 KASSERT(bp->b_offset != NOOFFSET, 2556 ("vfs_vmio_iodone: bp %p has no buffer offset", bp)); 2557 2558 bogus = false; 2559 iosize = bp->b_bcount - bp->b_resid; 2560 VM_OBJECT_WLOCK(obj); 2561 for (i = 0; i < bp->b_npages; i++) { 2562 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 2563 if (resid > iosize) 2564 resid = iosize; 2565 2566 /* 2567 * cleanup bogus pages, restoring the originals 2568 */ 2569 m = bp->b_pages[i]; 2570 if (m == bogus_page) { 2571 bogus = true; 2572 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 2573 if (m == NULL) 2574 panic("biodone: page disappeared!"); 2575 bp->b_pages[i] = m; 2576 } else if ((bp->b_iocmd == BIO_READ) && resid > 0) { 2577 /* 2578 * In the write case, the valid and clean bits are 2579 * already changed correctly ( see bdwrite() ), so we 2580 * only need to do this here in the read case. 2581 */ 2582 KASSERT((m->dirty & vm_page_bits(foff & PAGE_MASK, 2583 resid)) == 0, ("vfs_vmio_iodone: page %p " 2584 "has unexpected dirty bits", m)); 2585 vfs_page_set_valid(bp, foff, m); 2586 } 2587 KASSERT(OFF_TO_IDX(foff) == m->pindex, 2588 ("vfs_vmio_iodone: foff(%jd)/pindex(%ju) mismatch", 2589 (intmax_t)foff, (uintmax_t)m->pindex)); 2590 2591 vm_page_sunbusy(m); 2592 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2593 iosize -= resid; 2594 } 2595 vm_object_pip_wakeupn(obj, bp->b_npages); 2596 VM_OBJECT_WUNLOCK(obj); 2597 if (bogus && buf_mapped(bp)) { 2598 BUF_CHECK_MAPPED(bp); 2599 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 2600 bp->b_pages, bp->b_npages); 2601 } 2602 } 2603 2604 /* 2605 * Unwire a page held by a buf and place it on the appropriate vm queue. 2606 */ 2607 static void 2608 vfs_vmio_unwire(struct buf *bp, vm_page_t m) 2609 { 2610 bool freed; 2611 2612 vm_page_lock(m); 2613 if (vm_page_unwire(m, PQ_NONE)) { 2614 /* 2615 * Determine if the page should be freed before adding 2616 * it to the inactive queue. 2617 */ 2618 if (m->valid == 0) { 2619 freed = !vm_page_busied(m); 2620 if (freed) 2621 vm_page_free(m); 2622 } else if ((bp->b_flags & B_DIRECT) != 0) 2623 freed = vm_page_try_to_free(m); 2624 else 2625 freed = false; 2626 if (!freed) { 2627 /* 2628 * If the page is unlikely to be reused, let the 2629 * VM know. Otherwise, maintain LRU page 2630 * ordering and put the page at the tail of the 2631 * inactive queue. 2632 */ 2633 if ((bp->b_flags & B_NOREUSE) != 0) 2634 vm_page_deactivate_noreuse(m); 2635 else 2636 vm_page_deactivate(m); 2637 } 2638 } 2639 vm_page_unlock(m); 2640 } 2641 2642 /* 2643 * Perform page invalidation when a buffer is released. The fully invalid 2644 * pages will be reclaimed later in vfs_vmio_truncate(). 2645 */ 2646 static void 2647 vfs_vmio_invalidate(struct buf *bp) 2648 { 2649 vm_object_t obj; 2650 vm_page_t m; 2651 int i, resid, poffset, presid; 2652 2653 if (buf_mapped(bp)) { 2654 BUF_CHECK_MAPPED(bp); 2655 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages); 2656 } else 2657 BUF_CHECK_UNMAPPED(bp); 2658 /* 2659 * Get the base offset and length of the buffer. Note that 2660 * in the VMIO case if the buffer block size is not 2661 * page-aligned then b_data pointer may not be page-aligned. 2662 * But our b_pages[] array *IS* page aligned. 2663 * 2664 * block sizes less then DEV_BSIZE (usually 512) are not 2665 * supported due to the page granularity bits (m->valid, 2666 * m->dirty, etc...). 2667 * 2668 * See man buf(9) for more information 2669 */ 2670 obj = bp->b_bufobj->bo_object; 2671 resid = bp->b_bufsize; 2672 poffset = bp->b_offset & PAGE_MASK; 2673 VM_OBJECT_WLOCK(obj); 2674 for (i = 0; i < bp->b_npages; i++) { 2675 m = bp->b_pages[i]; 2676 if (m == bogus_page) 2677 panic("vfs_vmio_invalidate: Unexpected bogus page."); 2678 bp->b_pages[i] = NULL; 2679 2680 presid = resid > (PAGE_SIZE - poffset) ? 2681 (PAGE_SIZE - poffset) : resid; 2682 KASSERT(presid >= 0, ("brelse: extra page")); 2683 while (vm_page_xbusied(m)) { 2684 vm_page_lock(m); 2685 VM_OBJECT_WUNLOCK(obj); 2686 vm_page_busy_sleep(m, "mbncsh", true); 2687 VM_OBJECT_WLOCK(obj); 2688 } 2689 if (pmap_page_wired_mappings(m) == 0) 2690 vm_page_set_invalid(m, poffset, presid); 2691 vfs_vmio_unwire(bp, m); 2692 resid -= presid; 2693 poffset = 0; 2694 } 2695 VM_OBJECT_WUNLOCK(obj); 2696 bp->b_npages = 0; 2697 } 2698 2699 /* 2700 * Page-granular truncation of an existing VMIO buffer. 2701 */ 2702 static void 2703 vfs_vmio_truncate(struct buf *bp, int desiredpages) 2704 { 2705 vm_object_t obj; 2706 vm_page_t m; 2707 int i; 2708 2709 if (bp->b_npages == desiredpages) 2710 return; 2711 2712 if (buf_mapped(bp)) { 2713 BUF_CHECK_MAPPED(bp); 2714 pmap_qremove((vm_offset_t)trunc_page((vm_offset_t)bp->b_data) + 2715 (desiredpages << PAGE_SHIFT), bp->b_npages - desiredpages); 2716 } else 2717 BUF_CHECK_UNMAPPED(bp); 2718 obj = bp->b_bufobj->bo_object; 2719 if (obj != NULL) 2720 VM_OBJECT_WLOCK(obj); 2721 for (i = desiredpages; i < bp->b_npages; i++) { 2722 m = bp->b_pages[i]; 2723 KASSERT(m != bogus_page, ("allocbuf: bogus page found")); 2724 bp->b_pages[i] = NULL; 2725 vfs_vmio_unwire(bp, m); 2726 } 2727 if (obj != NULL) 2728 VM_OBJECT_WUNLOCK(obj); 2729 bp->b_npages = desiredpages; 2730 } 2731 2732 /* 2733 * Byte granular extension of VMIO buffers. 2734 */ 2735 static void 2736 vfs_vmio_extend(struct buf *bp, int desiredpages, int size) 2737 { 2738 /* 2739 * We are growing the buffer, possibly in a 2740 * byte-granular fashion. 2741 */ 2742 vm_object_t obj; 2743 vm_offset_t toff; 2744 vm_offset_t tinc; 2745 vm_page_t m; 2746 2747 /* 2748 * Step 1, bring in the VM pages from the object, allocating 2749 * them if necessary. We must clear B_CACHE if these pages 2750 * are not valid for the range covered by the buffer. 2751 */ 2752 obj = bp->b_bufobj->bo_object; 2753 VM_OBJECT_WLOCK(obj); 2754 if (bp->b_npages < desiredpages) { 2755 /* 2756 * We must allocate system pages since blocking 2757 * here could interfere with paging I/O, no 2758 * matter which process we are. 2759 * 2760 * Only exclusive busy can be tested here. 2761 * Blocking on shared busy might lead to 2762 * deadlocks once allocbuf() is called after 2763 * pages are vfs_busy_pages(). 2764 */ 2765 (void)vm_page_grab_pages(obj, 2766 OFF_TO_IDX(bp->b_offset) + bp->b_npages, 2767 VM_ALLOC_SYSTEM | VM_ALLOC_IGN_SBUSY | 2768 VM_ALLOC_NOBUSY | VM_ALLOC_WIRED, 2769 &bp->b_pages[bp->b_npages], desiredpages - bp->b_npages); 2770 bp->b_npages = desiredpages; 2771 } 2772 2773 /* 2774 * Step 2. We've loaded the pages into the buffer, 2775 * we have to figure out if we can still have B_CACHE 2776 * set. Note that B_CACHE is set according to the 2777 * byte-granular range ( bcount and size ), not the 2778 * aligned range ( newbsize ). 2779 * 2780 * The VM test is against m->valid, which is DEV_BSIZE 2781 * aligned. Needless to say, the validity of the data 2782 * needs to also be DEV_BSIZE aligned. Note that this 2783 * fails with NFS if the server or some other client 2784 * extends the file's EOF. If our buffer is resized, 2785 * B_CACHE may remain set! XXX 2786 */ 2787 toff = bp->b_bcount; 2788 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 2789 while ((bp->b_flags & B_CACHE) && toff < size) { 2790 vm_pindex_t pi; 2791 2792 if (tinc > (size - toff)) 2793 tinc = size - toff; 2794 pi = ((bp->b_offset & PAGE_MASK) + toff) >> PAGE_SHIFT; 2795 m = bp->b_pages[pi]; 2796 vfs_buf_test_cache(bp, bp->b_offset, toff, tinc, m); 2797 toff += tinc; 2798 tinc = PAGE_SIZE; 2799 } 2800 VM_OBJECT_WUNLOCK(obj); 2801 2802 /* 2803 * Step 3, fixup the KVA pmap. 2804 */ 2805 if (buf_mapped(bp)) 2806 bpmap_qenter(bp); 2807 else 2808 BUF_CHECK_UNMAPPED(bp); 2809 } 2810 2811 /* 2812 * Check to see if a block at a particular lbn is available for a clustered 2813 * write. 2814 */ 2815 static int 2816 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 2817 { 2818 struct buf *bpa; 2819 int match; 2820 2821 match = 0; 2822 2823 /* If the buf isn't in core skip it */ 2824 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 2825 return (0); 2826 2827 /* If the buf is busy we don't want to wait for it */ 2828 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2829 return (0); 2830 2831 /* Only cluster with valid clusterable delayed write buffers */ 2832 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 2833 (B_DELWRI | B_CLUSTEROK)) 2834 goto done; 2835 2836 if (bpa->b_bufsize != size) 2837 goto done; 2838 2839 /* 2840 * Check to see if it is in the expected place on disk and that the 2841 * block has been mapped. 2842 */ 2843 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 2844 match = 1; 2845 done: 2846 BUF_UNLOCK(bpa); 2847 return (match); 2848 } 2849 2850 /* 2851 * vfs_bio_awrite: 2852 * 2853 * Implement clustered async writes for clearing out B_DELWRI buffers. 2854 * This is much better then the old way of writing only one buffer at 2855 * a time. Note that we may not be presented with the buffers in the 2856 * correct order, so we search for the cluster in both directions. 2857 */ 2858 int 2859 vfs_bio_awrite(struct buf *bp) 2860 { 2861 struct bufobj *bo; 2862 int i; 2863 int j; 2864 daddr_t lblkno = bp->b_lblkno; 2865 struct vnode *vp = bp->b_vp; 2866 int ncl; 2867 int nwritten; 2868 int size; 2869 int maxcl; 2870 int gbflags; 2871 2872 bo = &vp->v_bufobj; 2873 gbflags = (bp->b_data == unmapped_buf) ? GB_UNMAPPED : 0; 2874 /* 2875 * right now we support clustered writing only to regular files. If 2876 * we find a clusterable block we could be in the middle of a cluster 2877 * rather then at the beginning. 2878 */ 2879 if ((vp->v_type == VREG) && 2880 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 2881 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 2882 2883 size = vp->v_mount->mnt_stat.f_iosize; 2884 maxcl = MAXPHYS / size; 2885 2886 BO_RLOCK(bo); 2887 for (i = 1; i < maxcl; i++) 2888 if (vfs_bio_clcheck(vp, size, lblkno + i, 2889 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 2890 break; 2891 2892 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 2893 if (vfs_bio_clcheck(vp, size, lblkno - j, 2894 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 2895 break; 2896 BO_RUNLOCK(bo); 2897 --j; 2898 ncl = i + j; 2899 /* 2900 * this is a possible cluster write 2901 */ 2902 if (ncl != 1) { 2903 BUF_UNLOCK(bp); 2904 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl, 2905 gbflags); 2906 return (nwritten); 2907 } 2908 } 2909 bremfree(bp); 2910 bp->b_flags |= B_ASYNC; 2911 /* 2912 * default (old) behavior, writing out only one block 2913 * 2914 * XXX returns b_bufsize instead of b_bcount for nwritten? 2915 */ 2916 nwritten = bp->b_bufsize; 2917 (void) bwrite(bp); 2918 2919 return (nwritten); 2920 } 2921 2922 /* 2923 * getnewbuf_kva: 2924 * 2925 * Allocate KVA for an empty buf header according to gbflags. 2926 */ 2927 static int 2928 getnewbuf_kva(struct buf *bp, int gbflags, int maxsize) 2929 { 2930 2931 if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_UNMAPPED) { 2932 /* 2933 * In order to keep fragmentation sane we only allocate kva 2934 * in BKVASIZE chunks. XXX with vmem we can do page size. 2935 */ 2936 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2937 2938 if (maxsize != bp->b_kvasize && 2939 bufkva_alloc(bp, maxsize, gbflags)) 2940 return (ENOSPC); 2941 } 2942 return (0); 2943 } 2944 2945 /* 2946 * getnewbuf: 2947 * 2948 * Find and initialize a new buffer header, freeing up existing buffers 2949 * in the bufqueues as necessary. The new buffer is returned locked. 2950 * 2951 * We block if: 2952 * We have insufficient buffer headers 2953 * We have insufficient buffer space 2954 * buffer_arena is too fragmented ( space reservation fails ) 2955 * If we have to flush dirty buffers ( but we try to avoid this ) 2956 * 2957 * The caller is responsible for releasing the reserved bufspace after 2958 * allocbuf() is called. 2959 */ 2960 static struct buf * 2961 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int maxsize, int gbflags) 2962 { 2963 struct buf *bp; 2964 bool metadata, reserved; 2965 2966 bp = NULL; 2967 KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 2968 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 2969 if (!unmapped_buf_allowed) 2970 gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC); 2971 2972 if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 || 2973 vp->v_type == VCHR) 2974 metadata = true; 2975 else 2976 metadata = false; 2977 atomic_add_int(&getnewbufcalls, 1); 2978 reserved = false; 2979 do { 2980 if (reserved == false && 2981 bufspace_reserve(maxsize, metadata) != 0) 2982 continue; 2983 reserved = true; 2984 if ((bp = buf_alloc()) == NULL) 2985 continue; 2986 if (getnewbuf_kva(bp, gbflags, maxsize) == 0) 2987 return (bp); 2988 break; 2989 } while(buf_scan(false) == 0); 2990 2991 if (reserved) 2992 atomic_subtract_long(&bufspace, maxsize); 2993 if (bp != NULL) { 2994 bp->b_flags |= B_INVAL; 2995 brelse(bp); 2996 } 2997 bufspace_wait(vp, gbflags, slpflag, slptimeo); 2998 2999 return (NULL); 3000 } 3001 3002 /* 3003 * buf_daemon: 3004 * 3005 * buffer flushing daemon. Buffers are normally flushed by the 3006 * update daemon but if it cannot keep up this process starts to 3007 * take the load in an attempt to prevent getnewbuf() from blocking. 3008 */ 3009 static struct kproc_desc buf_kp = { 3010 "bufdaemon", 3011 buf_daemon, 3012 &bufdaemonproc 3013 }; 3014 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 3015 3016 static int 3017 buf_flush(struct vnode *vp, int target) 3018 { 3019 int flushed; 3020 3021 flushed = flushbufqueues(vp, target, 0); 3022 if (flushed == 0) { 3023 /* 3024 * Could not find any buffers without rollback 3025 * dependencies, so just write the first one 3026 * in the hopes of eventually making progress. 3027 */ 3028 if (vp != NULL && target > 2) 3029 target /= 2; 3030 flushbufqueues(vp, target, 1); 3031 } 3032 return (flushed); 3033 } 3034 3035 static void 3036 buf_daemon() 3037 { 3038 int lodirty; 3039 3040 /* 3041 * This process needs to be suspended prior to shutdown sync. 3042 */ 3043 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 3044 SHUTDOWN_PRI_LAST); 3045 3046 /* 3047 * This process is allowed to take the buffer cache to the limit 3048 */ 3049 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 3050 mtx_lock(&bdlock); 3051 for (;;) { 3052 bd_request = 0; 3053 mtx_unlock(&bdlock); 3054 3055 kproc_suspend_check(bufdaemonproc); 3056 lodirty = lodirtybuffers; 3057 if (bd_speedupreq) { 3058 lodirty = numdirtybuffers / 2; 3059 bd_speedupreq = 0; 3060 } 3061 /* 3062 * Do the flush. Limit the amount of in-transit I/O we 3063 * allow to build up, otherwise we would completely saturate 3064 * the I/O system. 3065 */ 3066 while (numdirtybuffers > lodirty) { 3067 if (buf_flush(NULL, numdirtybuffers - lodirty) == 0) 3068 break; 3069 kern_yield(PRI_USER); 3070 } 3071 3072 /* 3073 * Only clear bd_request if we have reached our low water 3074 * mark. The buf_daemon normally waits 1 second and 3075 * then incrementally flushes any dirty buffers that have 3076 * built up, within reason. 3077 * 3078 * If we were unable to hit our low water mark and couldn't 3079 * find any flushable buffers, we sleep for a short period 3080 * to avoid endless loops on unlockable buffers. 3081 */ 3082 mtx_lock(&bdlock); 3083 if (numdirtybuffers <= lodirtybuffers) { 3084 /* 3085 * We reached our low water mark, reset the 3086 * request and sleep until we are needed again. 3087 * The sleep is just so the suspend code works. 3088 */ 3089 bd_request = 0; 3090 /* 3091 * Do an extra wakeup in case dirty threshold 3092 * changed via sysctl and the explicit transition 3093 * out of shortfall was missed. 3094 */ 3095 bdirtywakeup(); 3096 if (runningbufspace <= lorunningspace) 3097 runningwakeup(); 3098 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 3099 } else { 3100 /* 3101 * We couldn't find any flushable dirty buffers but 3102 * still have too many dirty buffers, we 3103 * have to sleep and try again. (rare) 3104 */ 3105 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 3106 } 3107 } 3108 } 3109 3110 /* 3111 * flushbufqueues: 3112 * 3113 * Try to flush a buffer in the dirty queue. We must be careful to 3114 * free up B_INVAL buffers instead of write them, which NFS is 3115 * particularly sensitive to. 3116 */ 3117 static int flushwithdeps = 0; 3118 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 3119 0, "Number of buffers flushed with dependecies that require rollbacks"); 3120 3121 static int 3122 flushbufqueues(struct vnode *lvp, int target, int flushdeps) 3123 { 3124 struct buf *sentinel; 3125 struct vnode *vp; 3126 struct mount *mp; 3127 struct buf *bp; 3128 int hasdeps; 3129 int flushed; 3130 int queue; 3131 int error; 3132 bool unlock; 3133 3134 flushed = 0; 3135 queue = QUEUE_DIRTY; 3136 bp = NULL; 3137 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 3138 sentinel->b_qindex = QUEUE_SENTINEL; 3139 mtx_lock(&bqlocks[queue]); 3140 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist); 3141 mtx_unlock(&bqlocks[queue]); 3142 while (flushed != target) { 3143 maybe_yield(); 3144 mtx_lock(&bqlocks[queue]); 3145 bp = TAILQ_NEXT(sentinel, b_freelist); 3146 if (bp != NULL) { 3147 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 3148 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel, 3149 b_freelist); 3150 } else { 3151 mtx_unlock(&bqlocks[queue]); 3152 break; 3153 } 3154 /* 3155 * Skip sentinels inserted by other invocations of the 3156 * flushbufqueues(), taking care to not reorder them. 3157 * 3158 * Only flush the buffers that belong to the 3159 * vnode locked by the curthread. 3160 */ 3161 if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL && 3162 bp->b_vp != lvp)) { 3163 mtx_unlock(&bqlocks[queue]); 3164 continue; 3165 } 3166 error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL); 3167 mtx_unlock(&bqlocks[queue]); 3168 if (error != 0) 3169 continue; 3170 3171 /* 3172 * BKGRDINPROG can only be set with the buf and bufobj 3173 * locks both held. We tolerate a race to clear it here. 3174 */ 3175 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 3176 (bp->b_flags & B_DELWRI) == 0) { 3177 BUF_UNLOCK(bp); 3178 continue; 3179 } 3180 if (bp->b_flags & B_INVAL) { 3181 bremfreef(bp); 3182 brelse(bp); 3183 flushed++; 3184 continue; 3185 } 3186 3187 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 3188 if (flushdeps == 0) { 3189 BUF_UNLOCK(bp); 3190 continue; 3191 } 3192 hasdeps = 1; 3193 } else 3194 hasdeps = 0; 3195 /* 3196 * We must hold the lock on a vnode before writing 3197 * one of its buffers. Otherwise we may confuse, or 3198 * in the case of a snapshot vnode, deadlock the 3199 * system. 3200 * 3201 * The lock order here is the reverse of the normal 3202 * of vnode followed by buf lock. This is ok because 3203 * the NOWAIT will prevent deadlock. 3204 */ 3205 vp = bp->b_vp; 3206 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 3207 BUF_UNLOCK(bp); 3208 continue; 3209 } 3210 if (lvp == NULL) { 3211 unlock = true; 3212 error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT); 3213 } else { 3214 ASSERT_VOP_LOCKED(vp, "getbuf"); 3215 unlock = false; 3216 error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 : 3217 vn_lock(vp, LK_TRYUPGRADE); 3218 } 3219 if (error == 0) { 3220 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 3221 bp, bp->b_vp, bp->b_flags); 3222 if (curproc == bufdaemonproc) { 3223 vfs_bio_awrite(bp); 3224 } else { 3225 bremfree(bp); 3226 bwrite(bp); 3227 notbufdflushes++; 3228 } 3229 vn_finished_write(mp); 3230 if (unlock) 3231 VOP_UNLOCK(vp, 0); 3232 flushwithdeps += hasdeps; 3233 flushed++; 3234 3235 /* 3236 * Sleeping on runningbufspace while holding 3237 * vnode lock leads to deadlock. 3238 */ 3239 if (curproc == bufdaemonproc && 3240 runningbufspace > hirunningspace) 3241 waitrunningbufspace(); 3242 continue; 3243 } 3244 vn_finished_write(mp); 3245 BUF_UNLOCK(bp); 3246 } 3247 mtx_lock(&bqlocks[queue]); 3248 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 3249 mtx_unlock(&bqlocks[queue]); 3250 free(sentinel, M_TEMP); 3251 return (flushed); 3252 } 3253 3254 /* 3255 * Check to see if a block is currently memory resident. 3256 */ 3257 struct buf * 3258 incore(struct bufobj *bo, daddr_t blkno) 3259 { 3260 struct buf *bp; 3261 3262 BO_RLOCK(bo); 3263 bp = gbincore(bo, blkno); 3264 BO_RUNLOCK(bo); 3265 return (bp); 3266 } 3267 3268 /* 3269 * Returns true if no I/O is needed to access the 3270 * associated VM object. This is like incore except 3271 * it also hunts around in the VM system for the data. 3272 */ 3273 3274 static int 3275 inmem(struct vnode * vp, daddr_t blkno) 3276 { 3277 vm_object_t obj; 3278 vm_offset_t toff, tinc, size; 3279 vm_page_t m; 3280 vm_ooffset_t off; 3281 3282 ASSERT_VOP_LOCKED(vp, "inmem"); 3283 3284 if (incore(&vp->v_bufobj, blkno)) 3285 return 1; 3286 if (vp->v_mount == NULL) 3287 return 0; 3288 obj = vp->v_object; 3289 if (obj == NULL) 3290 return (0); 3291 3292 size = PAGE_SIZE; 3293 if (size > vp->v_mount->mnt_stat.f_iosize) 3294 size = vp->v_mount->mnt_stat.f_iosize; 3295 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 3296 3297 VM_OBJECT_RLOCK(obj); 3298 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 3299 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 3300 if (!m) 3301 goto notinmem; 3302 tinc = size; 3303 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 3304 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 3305 if (vm_page_is_valid(m, 3306 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 3307 goto notinmem; 3308 } 3309 VM_OBJECT_RUNLOCK(obj); 3310 return 1; 3311 3312 notinmem: 3313 VM_OBJECT_RUNLOCK(obj); 3314 return (0); 3315 } 3316 3317 /* 3318 * Set the dirty range for a buffer based on the status of the dirty 3319 * bits in the pages comprising the buffer. The range is limited 3320 * to the size of the buffer. 3321 * 3322 * Tell the VM system that the pages associated with this buffer 3323 * are clean. This is used for delayed writes where the data is 3324 * going to go to disk eventually without additional VM intevention. 3325 * 3326 * Note that while we only really need to clean through to b_bcount, we 3327 * just go ahead and clean through to b_bufsize. 3328 */ 3329 static void 3330 vfs_clean_pages_dirty_buf(struct buf *bp) 3331 { 3332 vm_ooffset_t foff, noff, eoff; 3333 vm_page_t m; 3334 int i; 3335 3336 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 3337 return; 3338 3339 foff = bp->b_offset; 3340 KASSERT(bp->b_offset != NOOFFSET, 3341 ("vfs_clean_pages_dirty_buf: no buffer offset")); 3342 3343 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 3344 vfs_drain_busy_pages(bp); 3345 vfs_setdirty_locked_object(bp); 3346 for (i = 0; i < bp->b_npages; i++) { 3347 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3348 eoff = noff; 3349 if (eoff > bp->b_offset + bp->b_bufsize) 3350 eoff = bp->b_offset + bp->b_bufsize; 3351 m = bp->b_pages[i]; 3352 vfs_page_set_validclean(bp, foff, m); 3353 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3354 foff = noff; 3355 } 3356 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 3357 } 3358 3359 static void 3360 vfs_setdirty_locked_object(struct buf *bp) 3361 { 3362 vm_object_t object; 3363 int i; 3364 3365 object = bp->b_bufobj->bo_object; 3366 VM_OBJECT_ASSERT_WLOCKED(object); 3367 3368 /* 3369 * We qualify the scan for modified pages on whether the 3370 * object has been flushed yet. 3371 */ 3372 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) { 3373 vm_offset_t boffset; 3374 vm_offset_t eoffset; 3375 3376 /* 3377 * test the pages to see if they have been modified directly 3378 * by users through the VM system. 3379 */ 3380 for (i = 0; i < bp->b_npages; i++) 3381 vm_page_test_dirty(bp->b_pages[i]); 3382 3383 /* 3384 * Calculate the encompassing dirty range, boffset and eoffset, 3385 * (eoffset - boffset) bytes. 3386 */ 3387 3388 for (i = 0; i < bp->b_npages; i++) { 3389 if (bp->b_pages[i]->dirty) 3390 break; 3391 } 3392 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3393 3394 for (i = bp->b_npages - 1; i >= 0; --i) { 3395 if (bp->b_pages[i]->dirty) { 3396 break; 3397 } 3398 } 3399 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 3400 3401 /* 3402 * Fit it to the buffer. 3403 */ 3404 3405 if (eoffset > bp->b_bcount) 3406 eoffset = bp->b_bcount; 3407 3408 /* 3409 * If we have a good dirty range, merge with the existing 3410 * dirty range. 3411 */ 3412 3413 if (boffset < eoffset) { 3414 if (bp->b_dirtyoff > boffset) 3415 bp->b_dirtyoff = boffset; 3416 if (bp->b_dirtyend < eoffset) 3417 bp->b_dirtyend = eoffset; 3418 } 3419 } 3420 } 3421 3422 /* 3423 * Allocate the KVA mapping for an existing buffer. 3424 * If an unmapped buffer is provided but a mapped buffer is requested, take 3425 * also care to properly setup mappings between pages and KVA. 3426 */ 3427 static void 3428 bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags) 3429 { 3430 int bsize, maxsize, need_mapping, need_kva; 3431 off_t offset; 3432 3433 need_mapping = bp->b_data == unmapped_buf && 3434 (gbflags & GB_UNMAPPED) == 0; 3435 need_kva = bp->b_kvabase == unmapped_buf && 3436 bp->b_data == unmapped_buf && 3437 (gbflags & GB_KVAALLOC) != 0; 3438 if (!need_mapping && !need_kva) 3439 return; 3440 3441 BUF_CHECK_UNMAPPED(bp); 3442 3443 if (need_mapping && bp->b_kvabase != unmapped_buf) { 3444 /* 3445 * Buffer is not mapped, but the KVA was already 3446 * reserved at the time of the instantiation. Use the 3447 * allocated space. 3448 */ 3449 goto has_addr; 3450 } 3451 3452 /* 3453 * Calculate the amount of the address space we would reserve 3454 * if the buffer was mapped. 3455 */ 3456 bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize; 3457 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3458 offset = blkno * bsize; 3459 maxsize = size + (offset & PAGE_MASK); 3460 maxsize = imax(maxsize, bsize); 3461 3462 while (bufkva_alloc(bp, maxsize, gbflags) != 0) { 3463 if ((gbflags & GB_NOWAIT_BD) != 0) { 3464 /* 3465 * XXXKIB: defragmentation cannot 3466 * succeed, not sure what else to do. 3467 */ 3468 panic("GB_NOWAIT_BD and GB_UNMAPPED %p", bp); 3469 } 3470 atomic_add_int(&mappingrestarts, 1); 3471 bufspace_wait(bp->b_vp, gbflags, 0, 0); 3472 } 3473 has_addr: 3474 if (need_mapping) { 3475 /* b_offset is handled by bpmap_qenter. */ 3476 bp->b_data = bp->b_kvabase; 3477 BUF_CHECK_MAPPED(bp); 3478 bpmap_qenter(bp); 3479 } 3480 } 3481 3482 /* 3483 * getblk: 3484 * 3485 * Get a block given a specified block and offset into a file/device. 3486 * The buffers B_DONE bit will be cleared on return, making it almost 3487 * ready for an I/O initiation. B_INVAL may or may not be set on 3488 * return. The caller should clear B_INVAL prior to initiating a 3489 * READ. 3490 * 3491 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 3492 * an existing buffer. 3493 * 3494 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 3495 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 3496 * and then cleared based on the backing VM. If the previous buffer is 3497 * non-0-sized but invalid, B_CACHE will be cleared. 3498 * 3499 * If getblk() must create a new buffer, the new buffer is returned with 3500 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 3501 * case it is returned with B_INVAL clear and B_CACHE set based on the 3502 * backing VM. 3503 * 3504 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 3505 * B_CACHE bit is clear. 3506 * 3507 * What this means, basically, is that the caller should use B_CACHE to 3508 * determine whether the buffer is fully valid or not and should clear 3509 * B_INVAL prior to issuing a read. If the caller intends to validate 3510 * the buffer by loading its data area with something, the caller needs 3511 * to clear B_INVAL. If the caller does this without issuing an I/O, 3512 * the caller should set B_CACHE ( as an optimization ), else the caller 3513 * should issue the I/O and biodone() will set B_CACHE if the I/O was 3514 * a write attempt or if it was a successful read. If the caller 3515 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 3516 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 3517 */ 3518 struct buf * 3519 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 3520 int flags) 3521 { 3522 struct buf *bp; 3523 struct bufobj *bo; 3524 int bsize, error, maxsize, vmio; 3525 off_t offset; 3526 3527 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 3528 KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC, 3529 ("GB_KVAALLOC only makes sense with GB_UNMAPPED")); 3530 ASSERT_VOP_LOCKED(vp, "getblk"); 3531 if (size > maxbcachebuf) 3532 panic("getblk: size(%d) > maxbcachebuf(%d)\n", size, 3533 maxbcachebuf); 3534 if (!unmapped_buf_allowed) 3535 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3536 3537 bo = &vp->v_bufobj; 3538 loop: 3539 BO_RLOCK(bo); 3540 bp = gbincore(bo, blkno); 3541 if (bp != NULL) { 3542 int lockflags; 3543 /* 3544 * Buffer is in-core. If the buffer is not busy nor managed, 3545 * it must be on a queue. 3546 */ 3547 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 3548 3549 if (flags & GB_LOCK_NOWAIT) 3550 lockflags |= LK_NOWAIT; 3551 3552 error = BUF_TIMELOCK(bp, lockflags, 3553 BO_LOCKPTR(bo), "getblk", slpflag, slptimeo); 3554 3555 /* 3556 * If we slept and got the lock we have to restart in case 3557 * the buffer changed identities. 3558 */ 3559 if (error == ENOLCK) 3560 goto loop; 3561 /* We timed out or were interrupted. */ 3562 else if (error) 3563 return (NULL); 3564 /* If recursed, assume caller knows the rules. */ 3565 else if (BUF_LOCKRECURSED(bp)) 3566 goto end; 3567 3568 /* 3569 * The buffer is locked. B_CACHE is cleared if the buffer is 3570 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 3571 * and for a VMIO buffer B_CACHE is adjusted according to the 3572 * backing VM cache. 3573 */ 3574 if (bp->b_flags & B_INVAL) 3575 bp->b_flags &= ~B_CACHE; 3576 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 3577 bp->b_flags |= B_CACHE; 3578 if (bp->b_flags & B_MANAGED) 3579 MPASS(bp->b_qindex == QUEUE_NONE); 3580 else 3581 bremfree(bp); 3582 3583 /* 3584 * check for size inconsistencies for non-VMIO case. 3585 */ 3586 if (bp->b_bcount != size) { 3587 if ((bp->b_flags & B_VMIO) == 0 || 3588 (size > bp->b_kvasize)) { 3589 if (bp->b_flags & B_DELWRI) { 3590 bp->b_flags |= B_NOCACHE; 3591 bwrite(bp); 3592 } else { 3593 if (LIST_EMPTY(&bp->b_dep)) { 3594 bp->b_flags |= B_RELBUF; 3595 brelse(bp); 3596 } else { 3597 bp->b_flags |= B_NOCACHE; 3598 bwrite(bp); 3599 } 3600 } 3601 goto loop; 3602 } 3603 } 3604 3605 /* 3606 * Handle the case of unmapped buffer which should 3607 * become mapped, or the buffer for which KVA 3608 * reservation is requested. 3609 */ 3610 bp_unmapped_get_kva(bp, blkno, size, flags); 3611 3612 /* 3613 * If the size is inconsistent in the VMIO case, we can resize 3614 * the buffer. This might lead to B_CACHE getting set or 3615 * cleared. If the size has not changed, B_CACHE remains 3616 * unchanged from its previous state. 3617 */ 3618 allocbuf(bp, size); 3619 3620 KASSERT(bp->b_offset != NOOFFSET, 3621 ("getblk: no buffer offset")); 3622 3623 /* 3624 * A buffer with B_DELWRI set and B_CACHE clear must 3625 * be committed before we can return the buffer in 3626 * order to prevent the caller from issuing a read 3627 * ( due to B_CACHE not being set ) and overwriting 3628 * it. 3629 * 3630 * Most callers, including NFS and FFS, need this to 3631 * operate properly either because they assume they 3632 * can issue a read if B_CACHE is not set, or because 3633 * ( for example ) an uncached B_DELWRI might loop due 3634 * to softupdates re-dirtying the buffer. In the latter 3635 * case, B_CACHE is set after the first write completes, 3636 * preventing further loops. 3637 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 3638 * above while extending the buffer, we cannot allow the 3639 * buffer to remain with B_CACHE set after the write 3640 * completes or it will represent a corrupt state. To 3641 * deal with this we set B_NOCACHE to scrap the buffer 3642 * after the write. 3643 * 3644 * We might be able to do something fancy, like setting 3645 * B_CACHE in bwrite() except if B_DELWRI is already set, 3646 * so the below call doesn't set B_CACHE, but that gets real 3647 * confusing. This is much easier. 3648 */ 3649 3650 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 3651 bp->b_flags |= B_NOCACHE; 3652 bwrite(bp); 3653 goto loop; 3654 } 3655 bp->b_flags &= ~B_DONE; 3656 } else { 3657 /* 3658 * Buffer is not in-core, create new buffer. The buffer 3659 * returned by getnewbuf() is locked. Note that the returned 3660 * buffer is also considered valid (not marked B_INVAL). 3661 */ 3662 BO_RUNLOCK(bo); 3663 /* 3664 * If the user does not want us to create the buffer, bail out 3665 * here. 3666 */ 3667 if (flags & GB_NOCREAT) 3668 return NULL; 3669 if (numfreebuffers == 0 && TD_IS_IDLETHREAD(curthread)) 3670 return NULL; 3671 3672 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize; 3673 KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize")); 3674 offset = blkno * bsize; 3675 vmio = vp->v_object != NULL; 3676 if (vmio) { 3677 maxsize = size + (offset & PAGE_MASK); 3678 } else { 3679 maxsize = size; 3680 /* Do not allow non-VMIO notmapped buffers. */ 3681 flags &= ~(GB_UNMAPPED | GB_KVAALLOC); 3682 } 3683 maxsize = imax(maxsize, bsize); 3684 3685 bp = getnewbuf(vp, slpflag, slptimeo, maxsize, flags); 3686 if (bp == NULL) { 3687 if (slpflag || slptimeo) 3688 return NULL; 3689 /* 3690 * XXX This is here until the sleep path is diagnosed 3691 * enough to work under very low memory conditions. 3692 * 3693 * There's an issue on low memory, 4BSD+non-preempt 3694 * systems (eg MIPS routers with 32MB RAM) where buffer 3695 * exhaustion occurs without sleeping for buffer 3696 * reclaimation. This just sticks in a loop and 3697 * constantly attempts to allocate a buffer, which 3698 * hits exhaustion and tries to wakeup bufdaemon. 3699 * This never happens because we never yield. 3700 * 3701 * The real solution is to identify and fix these cases 3702 * so we aren't effectively busy-waiting in a loop 3703 * until the reclaimation path has cycles to run. 3704 */ 3705 kern_yield(PRI_USER); 3706 goto loop; 3707 } 3708 3709 /* 3710 * This code is used to make sure that a buffer is not 3711 * created while the getnewbuf routine is blocked. 3712 * This can be a problem whether the vnode is locked or not. 3713 * If the buffer is created out from under us, we have to 3714 * throw away the one we just created. 3715 * 3716 * Note: this must occur before we associate the buffer 3717 * with the vp especially considering limitations in 3718 * the splay tree implementation when dealing with duplicate 3719 * lblkno's. 3720 */ 3721 BO_LOCK(bo); 3722 if (gbincore(bo, blkno)) { 3723 BO_UNLOCK(bo); 3724 bp->b_flags |= B_INVAL; 3725 brelse(bp); 3726 bufspace_release(maxsize); 3727 goto loop; 3728 } 3729 3730 /* 3731 * Insert the buffer into the hash, so that it can 3732 * be found by incore. 3733 */ 3734 bp->b_blkno = bp->b_lblkno = blkno; 3735 bp->b_offset = offset; 3736 bgetvp(vp, bp); 3737 BO_UNLOCK(bo); 3738 3739 /* 3740 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 3741 * buffer size starts out as 0, B_CACHE will be set by 3742 * allocbuf() for the VMIO case prior to it testing the 3743 * backing store for validity. 3744 */ 3745 3746 if (vmio) { 3747 bp->b_flags |= B_VMIO; 3748 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 3749 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 3750 bp, vp->v_object, bp->b_bufobj->bo_object)); 3751 } else { 3752 bp->b_flags &= ~B_VMIO; 3753 KASSERT(bp->b_bufobj->bo_object == NULL, 3754 ("ARGH! has b_bufobj->bo_object %p %p\n", 3755 bp, bp->b_bufobj->bo_object)); 3756 BUF_CHECK_MAPPED(bp); 3757 } 3758 3759 allocbuf(bp, size); 3760 bufspace_release(maxsize); 3761 bp->b_flags &= ~B_DONE; 3762 } 3763 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 3764 BUF_ASSERT_HELD(bp); 3765 end: 3766 buf_track(bp, __func__); 3767 KASSERT(bp->b_bufobj == bo, 3768 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 3769 return (bp); 3770 } 3771 3772 /* 3773 * Get an empty, disassociated buffer of given size. The buffer is initially 3774 * set to B_INVAL. 3775 */ 3776 struct buf * 3777 geteblk(int size, int flags) 3778 { 3779 struct buf *bp; 3780 int maxsize; 3781 3782 maxsize = (size + BKVAMASK) & ~BKVAMASK; 3783 while ((bp = getnewbuf(NULL, 0, 0, maxsize, flags)) == NULL) { 3784 if ((flags & GB_NOWAIT_BD) && 3785 (curthread->td_pflags & TDP_BUFNEED) != 0) 3786 return (NULL); 3787 } 3788 allocbuf(bp, size); 3789 bufspace_release(maxsize); 3790 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 3791 BUF_ASSERT_HELD(bp); 3792 return (bp); 3793 } 3794 3795 /* 3796 * Truncate the backing store for a non-vmio buffer. 3797 */ 3798 static void 3799 vfs_nonvmio_truncate(struct buf *bp, int newbsize) 3800 { 3801 3802 if (bp->b_flags & B_MALLOC) { 3803 /* 3804 * malloced buffers are not shrunk 3805 */ 3806 if (newbsize == 0) { 3807 bufmallocadjust(bp, 0); 3808 free(bp->b_data, M_BIOBUF); 3809 bp->b_data = bp->b_kvabase; 3810 bp->b_flags &= ~B_MALLOC; 3811 } 3812 return; 3813 } 3814 vm_hold_free_pages(bp, newbsize); 3815 bufspace_adjust(bp, newbsize); 3816 } 3817 3818 /* 3819 * Extend the backing for a non-VMIO buffer. 3820 */ 3821 static void 3822 vfs_nonvmio_extend(struct buf *bp, int newbsize) 3823 { 3824 caddr_t origbuf; 3825 int origbufsize; 3826 3827 /* 3828 * We only use malloced memory on the first allocation. 3829 * and revert to page-allocated memory when the buffer 3830 * grows. 3831 * 3832 * There is a potential smp race here that could lead 3833 * to bufmallocspace slightly passing the max. It 3834 * is probably extremely rare and not worth worrying 3835 * over. 3836 */ 3837 if (bp->b_bufsize == 0 && newbsize <= PAGE_SIZE/2 && 3838 bufmallocspace < maxbufmallocspace) { 3839 bp->b_data = malloc(newbsize, M_BIOBUF, M_WAITOK); 3840 bp->b_flags |= B_MALLOC; 3841 bufmallocadjust(bp, newbsize); 3842 return; 3843 } 3844 3845 /* 3846 * If the buffer is growing on its other-than-first 3847 * allocation then we revert to the page-allocation 3848 * scheme. 3849 */ 3850 origbuf = NULL; 3851 origbufsize = 0; 3852 if (bp->b_flags & B_MALLOC) { 3853 origbuf = bp->b_data; 3854 origbufsize = bp->b_bufsize; 3855 bp->b_data = bp->b_kvabase; 3856 bufmallocadjust(bp, 0); 3857 bp->b_flags &= ~B_MALLOC; 3858 newbsize = round_page(newbsize); 3859 } 3860 vm_hold_load_pages(bp, (vm_offset_t) bp->b_data + bp->b_bufsize, 3861 (vm_offset_t) bp->b_data + newbsize); 3862 if (origbuf != NULL) { 3863 bcopy(origbuf, bp->b_data, origbufsize); 3864 free(origbuf, M_BIOBUF); 3865 } 3866 bufspace_adjust(bp, newbsize); 3867 } 3868 3869 /* 3870 * This code constitutes the buffer memory from either anonymous system 3871 * memory (in the case of non-VMIO operations) or from an associated 3872 * VM object (in the case of VMIO operations). This code is able to 3873 * resize a buffer up or down. 3874 * 3875 * Note that this code is tricky, and has many complications to resolve 3876 * deadlock or inconsistent data situations. Tread lightly!!! 3877 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 3878 * the caller. Calling this code willy nilly can result in the loss of data. 3879 * 3880 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 3881 * B_CACHE for the non-VMIO case. 3882 */ 3883 int 3884 allocbuf(struct buf *bp, int size) 3885 { 3886 int newbsize; 3887 3888 BUF_ASSERT_HELD(bp); 3889 3890 if (bp->b_bcount == size) 3891 return (1); 3892 3893 if (bp->b_kvasize != 0 && bp->b_kvasize < size) 3894 panic("allocbuf: buffer too small"); 3895 3896 newbsize = roundup2(size, DEV_BSIZE); 3897 if ((bp->b_flags & B_VMIO) == 0) { 3898 if ((bp->b_flags & B_MALLOC) == 0) 3899 newbsize = round_page(newbsize); 3900 /* 3901 * Just get anonymous memory from the kernel. Don't 3902 * mess with B_CACHE. 3903 */ 3904 if (newbsize < bp->b_bufsize) 3905 vfs_nonvmio_truncate(bp, newbsize); 3906 else if (newbsize > bp->b_bufsize) 3907 vfs_nonvmio_extend(bp, newbsize); 3908 } else { 3909 int desiredpages; 3910 3911 desiredpages = (size == 0) ? 0 : 3912 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 3913 3914 if (bp->b_flags & B_MALLOC) 3915 panic("allocbuf: VMIO buffer can't be malloced"); 3916 /* 3917 * Set B_CACHE initially if buffer is 0 length or will become 3918 * 0-length. 3919 */ 3920 if (size == 0 || bp->b_bufsize == 0) 3921 bp->b_flags |= B_CACHE; 3922 3923 if (newbsize < bp->b_bufsize) 3924 vfs_vmio_truncate(bp, desiredpages); 3925 /* XXX This looks as if it should be newbsize > b_bufsize */ 3926 else if (size > bp->b_bcount) 3927 vfs_vmio_extend(bp, desiredpages, size); 3928 bufspace_adjust(bp, newbsize); 3929 } 3930 bp->b_bcount = size; /* requested buffer size. */ 3931 return (1); 3932 } 3933 3934 extern int inflight_transient_maps; 3935 3936 void 3937 biodone(struct bio *bp) 3938 { 3939 struct mtx *mtxp; 3940 void (*done)(struct bio *); 3941 vm_offset_t start, end; 3942 3943 biotrack(bp, __func__); 3944 if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) { 3945 bp->bio_flags &= ~BIO_TRANSIENT_MAPPING; 3946 bp->bio_flags |= BIO_UNMAPPED; 3947 start = trunc_page((vm_offset_t)bp->bio_data); 3948 end = round_page((vm_offset_t)bp->bio_data + bp->bio_length); 3949 bp->bio_data = unmapped_buf; 3950 pmap_qremove(start, atop(end - start)); 3951 vmem_free(transient_arena, start, end - start); 3952 atomic_add_int(&inflight_transient_maps, -1); 3953 } 3954 done = bp->bio_done; 3955 if (done == NULL) { 3956 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3957 mtx_lock(mtxp); 3958 bp->bio_flags |= BIO_DONE; 3959 wakeup(bp); 3960 mtx_unlock(mtxp); 3961 } else 3962 done(bp); 3963 } 3964 3965 /* 3966 * Wait for a BIO to finish. 3967 */ 3968 int 3969 biowait(struct bio *bp, const char *wchan) 3970 { 3971 struct mtx *mtxp; 3972 3973 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3974 mtx_lock(mtxp); 3975 while ((bp->bio_flags & BIO_DONE) == 0) 3976 msleep(bp, mtxp, PRIBIO, wchan, 0); 3977 mtx_unlock(mtxp); 3978 if (bp->bio_error != 0) 3979 return (bp->bio_error); 3980 if (!(bp->bio_flags & BIO_ERROR)) 3981 return (0); 3982 return (EIO); 3983 } 3984 3985 void 3986 biofinish(struct bio *bp, struct devstat *stat, int error) 3987 { 3988 3989 if (error) { 3990 bp->bio_error = error; 3991 bp->bio_flags |= BIO_ERROR; 3992 } 3993 if (stat != NULL) 3994 devstat_end_transaction_bio(stat, bp); 3995 biodone(bp); 3996 } 3997 3998 #if defined(BUF_TRACKING) || defined(FULL_BUF_TRACKING) 3999 void 4000 biotrack_buf(struct bio *bp, const char *location) 4001 { 4002 4003 buf_track(bp->bio_track_bp, location); 4004 } 4005 #endif 4006 4007 /* 4008 * bufwait: 4009 * 4010 * Wait for buffer I/O completion, returning error status. The buffer 4011 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 4012 * error and cleared. 4013 */ 4014 int 4015 bufwait(struct buf *bp) 4016 { 4017 if (bp->b_iocmd == BIO_READ) 4018 bwait(bp, PRIBIO, "biord"); 4019 else 4020 bwait(bp, PRIBIO, "biowr"); 4021 if (bp->b_flags & B_EINTR) { 4022 bp->b_flags &= ~B_EINTR; 4023 return (EINTR); 4024 } 4025 if (bp->b_ioflags & BIO_ERROR) { 4026 return (bp->b_error ? bp->b_error : EIO); 4027 } else { 4028 return (0); 4029 } 4030 } 4031 4032 /* 4033 * bufdone: 4034 * 4035 * Finish I/O on a buffer, optionally calling a completion function. 4036 * This is usually called from an interrupt so process blocking is 4037 * not allowed. 4038 * 4039 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 4040 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 4041 * assuming B_INVAL is clear. 4042 * 4043 * For the VMIO case, we set B_CACHE if the op was a read and no 4044 * read error occurred, or if the op was a write. B_CACHE is never 4045 * set if the buffer is invalid or otherwise uncacheable. 4046 * 4047 * biodone does not mess with B_INVAL, allowing the I/O routine or the 4048 * initiator to leave B_INVAL set to brelse the buffer out of existence 4049 * in the biodone routine. 4050 */ 4051 void 4052 bufdone(struct buf *bp) 4053 { 4054 struct bufobj *dropobj; 4055 void (*biodone)(struct buf *); 4056 4057 buf_track(bp, __func__); 4058 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 4059 dropobj = NULL; 4060 4061 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 4062 BUF_ASSERT_HELD(bp); 4063 4064 runningbufwakeup(bp); 4065 if (bp->b_iocmd == BIO_WRITE) 4066 dropobj = bp->b_bufobj; 4067 else if ((bp->b_flags & B_CKHASH) != 0) { 4068 KASSERT(buf_mapped(bp), ("biodone: bp %p not mapped", bp)); 4069 (*bp->b_ckhashcalc)(bp); 4070 } 4071 /* call optional completion function if requested */ 4072 if (bp->b_iodone != NULL) { 4073 biodone = bp->b_iodone; 4074 bp->b_iodone = NULL; 4075 (*biodone) (bp); 4076 if (dropobj) 4077 bufobj_wdrop(dropobj); 4078 return; 4079 } 4080 4081 bufdone_finish(bp); 4082 4083 if (dropobj) 4084 bufobj_wdrop(dropobj); 4085 } 4086 4087 void 4088 bufdone_finish(struct buf *bp) 4089 { 4090 BUF_ASSERT_HELD(bp); 4091 4092 if (!LIST_EMPTY(&bp->b_dep)) 4093 buf_complete(bp); 4094 4095 if (bp->b_flags & B_VMIO) { 4096 /* 4097 * Set B_CACHE if the op was a normal read and no error 4098 * occurred. B_CACHE is set for writes in the b*write() 4099 * routines. 4100 */ 4101 if (bp->b_iocmd == BIO_READ && 4102 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 4103 !(bp->b_ioflags & BIO_ERROR)) 4104 bp->b_flags |= B_CACHE; 4105 vfs_vmio_iodone(bp); 4106 } 4107 4108 /* 4109 * For asynchronous completions, release the buffer now. The brelse 4110 * will do a wakeup there if necessary - so no need to do a wakeup 4111 * here in the async case. The sync case always needs to do a wakeup. 4112 */ 4113 if (bp->b_flags & B_ASYNC) { 4114 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || 4115 (bp->b_ioflags & BIO_ERROR)) 4116 brelse(bp); 4117 else 4118 bqrelse(bp); 4119 } else 4120 bdone(bp); 4121 } 4122 4123 /* 4124 * This routine is called in lieu of iodone in the case of 4125 * incomplete I/O. This keeps the busy status for pages 4126 * consistent. 4127 */ 4128 void 4129 vfs_unbusy_pages(struct buf *bp) 4130 { 4131 int i; 4132 vm_object_t obj; 4133 vm_page_t m; 4134 4135 runningbufwakeup(bp); 4136 if (!(bp->b_flags & B_VMIO)) 4137 return; 4138 4139 obj = bp->b_bufobj->bo_object; 4140 VM_OBJECT_WLOCK(obj); 4141 for (i = 0; i < bp->b_npages; i++) { 4142 m = bp->b_pages[i]; 4143 if (m == bogus_page) { 4144 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 4145 if (!m) 4146 panic("vfs_unbusy_pages: page missing\n"); 4147 bp->b_pages[i] = m; 4148 if (buf_mapped(bp)) { 4149 BUF_CHECK_MAPPED(bp); 4150 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4151 bp->b_pages, bp->b_npages); 4152 } else 4153 BUF_CHECK_UNMAPPED(bp); 4154 } 4155 vm_page_sunbusy(m); 4156 } 4157 vm_object_pip_wakeupn(obj, bp->b_npages); 4158 VM_OBJECT_WUNLOCK(obj); 4159 } 4160 4161 /* 4162 * vfs_page_set_valid: 4163 * 4164 * Set the valid bits in a page based on the supplied offset. The 4165 * range is restricted to the buffer's size. 4166 * 4167 * This routine is typically called after a read completes. 4168 */ 4169 static void 4170 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4171 { 4172 vm_ooffset_t eoff; 4173 4174 /* 4175 * Compute the end offset, eoff, such that [off, eoff) does not span a 4176 * page boundary and eoff is not greater than the end of the buffer. 4177 * The end of the buffer, in this case, is our file EOF, not the 4178 * allocation size of the buffer. 4179 */ 4180 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 4181 if (eoff > bp->b_offset + bp->b_bcount) 4182 eoff = bp->b_offset + bp->b_bcount; 4183 4184 /* 4185 * Set valid range. This is typically the entire buffer and thus the 4186 * entire page. 4187 */ 4188 if (eoff > off) 4189 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off); 4190 } 4191 4192 /* 4193 * vfs_page_set_validclean: 4194 * 4195 * Set the valid bits and clear the dirty bits in a page based on the 4196 * supplied offset. The range is restricted to the buffer's size. 4197 */ 4198 static void 4199 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 4200 { 4201 vm_ooffset_t soff, eoff; 4202 4203 /* 4204 * Start and end offsets in buffer. eoff - soff may not cross a 4205 * page boundary or cross the end of the buffer. The end of the 4206 * buffer, in this case, is our file EOF, not the allocation size 4207 * of the buffer. 4208 */ 4209 soff = off; 4210 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4211 if (eoff > bp->b_offset + bp->b_bcount) 4212 eoff = bp->b_offset + bp->b_bcount; 4213 4214 /* 4215 * Set valid range. This is typically the entire buffer and thus the 4216 * entire page. 4217 */ 4218 if (eoff > soff) { 4219 vm_page_set_validclean( 4220 m, 4221 (vm_offset_t) (soff & PAGE_MASK), 4222 (vm_offset_t) (eoff - soff) 4223 ); 4224 } 4225 } 4226 4227 /* 4228 * Ensure that all buffer pages are not exclusive busied. If any page is 4229 * exclusive busy, drain it. 4230 */ 4231 void 4232 vfs_drain_busy_pages(struct buf *bp) 4233 { 4234 vm_page_t m; 4235 int i, last_busied; 4236 4237 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object); 4238 last_busied = 0; 4239 for (i = 0; i < bp->b_npages; i++) { 4240 m = bp->b_pages[i]; 4241 if (vm_page_xbusied(m)) { 4242 for (; last_busied < i; last_busied++) 4243 vm_page_sbusy(bp->b_pages[last_busied]); 4244 while (vm_page_xbusied(m)) { 4245 vm_page_lock(m); 4246 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4247 vm_page_busy_sleep(m, "vbpage", true); 4248 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4249 } 4250 } 4251 } 4252 for (i = 0; i < last_busied; i++) 4253 vm_page_sunbusy(bp->b_pages[i]); 4254 } 4255 4256 /* 4257 * This routine is called before a device strategy routine. 4258 * It is used to tell the VM system that paging I/O is in 4259 * progress, and treat the pages associated with the buffer 4260 * almost as being exclusive busy. Also the object paging_in_progress 4261 * flag is handled to make sure that the object doesn't become 4262 * inconsistent. 4263 * 4264 * Since I/O has not been initiated yet, certain buffer flags 4265 * such as BIO_ERROR or B_INVAL may be in an inconsistent state 4266 * and should be ignored. 4267 */ 4268 void 4269 vfs_busy_pages(struct buf *bp, int clear_modify) 4270 { 4271 vm_object_t obj; 4272 vm_ooffset_t foff; 4273 vm_page_t m; 4274 int i; 4275 bool bogus; 4276 4277 if (!(bp->b_flags & B_VMIO)) 4278 return; 4279 4280 obj = bp->b_bufobj->bo_object; 4281 foff = bp->b_offset; 4282 KASSERT(bp->b_offset != NOOFFSET, 4283 ("vfs_busy_pages: no buffer offset")); 4284 VM_OBJECT_WLOCK(obj); 4285 vfs_drain_busy_pages(bp); 4286 if (bp->b_bufsize != 0) 4287 vfs_setdirty_locked_object(bp); 4288 bogus = false; 4289 for (i = 0; i < bp->b_npages; i++) { 4290 m = bp->b_pages[i]; 4291 4292 if ((bp->b_flags & B_CLUSTER) == 0) { 4293 vm_object_pip_add(obj, 1); 4294 vm_page_sbusy(m); 4295 } 4296 /* 4297 * When readying a buffer for a read ( i.e 4298 * clear_modify == 0 ), it is important to do 4299 * bogus_page replacement for valid pages in 4300 * partially instantiated buffers. Partially 4301 * instantiated buffers can, in turn, occur when 4302 * reconstituting a buffer from its VM backing store 4303 * base. We only have to do this if B_CACHE is 4304 * clear ( which causes the I/O to occur in the 4305 * first place ). The replacement prevents the read 4306 * I/O from overwriting potentially dirty VM-backed 4307 * pages. XXX bogus page replacement is, uh, bogus. 4308 * It may not work properly with small-block devices. 4309 * We need to find a better way. 4310 */ 4311 if (clear_modify) { 4312 pmap_remove_write(m); 4313 vfs_page_set_validclean(bp, foff, m); 4314 } else if (m->valid == VM_PAGE_BITS_ALL && 4315 (bp->b_flags & B_CACHE) == 0) { 4316 bp->b_pages[i] = bogus_page; 4317 bogus = true; 4318 } 4319 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 4320 } 4321 VM_OBJECT_WUNLOCK(obj); 4322 if (bogus && buf_mapped(bp)) { 4323 BUF_CHECK_MAPPED(bp); 4324 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4325 bp->b_pages, bp->b_npages); 4326 } 4327 } 4328 4329 /* 4330 * vfs_bio_set_valid: 4331 * 4332 * Set the range within the buffer to valid. The range is 4333 * relative to the beginning of the buffer, b_offset. Note that 4334 * b_offset itself may be offset from the beginning of the first 4335 * page. 4336 */ 4337 void 4338 vfs_bio_set_valid(struct buf *bp, int base, int size) 4339 { 4340 int i, n; 4341 vm_page_t m; 4342 4343 if (!(bp->b_flags & B_VMIO)) 4344 return; 4345 4346 /* 4347 * Fixup base to be relative to beginning of first page. 4348 * Set initial n to be the maximum number of bytes in the 4349 * first page that can be validated. 4350 */ 4351 base += (bp->b_offset & PAGE_MASK); 4352 n = PAGE_SIZE - (base & PAGE_MASK); 4353 4354 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4355 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4356 m = bp->b_pages[i]; 4357 if (n > size) 4358 n = size; 4359 vm_page_set_valid_range(m, base & PAGE_MASK, n); 4360 base += n; 4361 size -= n; 4362 n = PAGE_SIZE; 4363 } 4364 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4365 } 4366 4367 /* 4368 * vfs_bio_clrbuf: 4369 * 4370 * If the specified buffer is a non-VMIO buffer, clear the entire 4371 * buffer. If the specified buffer is a VMIO buffer, clear and 4372 * validate only the previously invalid portions of the buffer. 4373 * This routine essentially fakes an I/O, so we need to clear 4374 * BIO_ERROR and B_INVAL. 4375 * 4376 * Note that while we only theoretically need to clear through b_bcount, 4377 * we go ahead and clear through b_bufsize. 4378 */ 4379 void 4380 vfs_bio_clrbuf(struct buf *bp) 4381 { 4382 int i, j, mask, sa, ea, slide; 4383 4384 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 4385 clrbuf(bp); 4386 return; 4387 } 4388 bp->b_flags &= ~B_INVAL; 4389 bp->b_ioflags &= ~BIO_ERROR; 4390 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 4391 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 4392 (bp->b_offset & PAGE_MASK) == 0) { 4393 if (bp->b_pages[0] == bogus_page) 4394 goto unlock; 4395 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 4396 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object); 4397 if ((bp->b_pages[0]->valid & mask) == mask) 4398 goto unlock; 4399 if ((bp->b_pages[0]->valid & mask) == 0) { 4400 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize); 4401 bp->b_pages[0]->valid |= mask; 4402 goto unlock; 4403 } 4404 } 4405 sa = bp->b_offset & PAGE_MASK; 4406 slide = 0; 4407 for (i = 0; i < bp->b_npages; i++, sa = 0) { 4408 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize); 4409 ea = slide & PAGE_MASK; 4410 if (ea == 0) 4411 ea = PAGE_SIZE; 4412 if (bp->b_pages[i] == bogus_page) 4413 continue; 4414 j = sa / DEV_BSIZE; 4415 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 4416 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object); 4417 if ((bp->b_pages[i]->valid & mask) == mask) 4418 continue; 4419 if ((bp->b_pages[i]->valid & mask) == 0) 4420 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa); 4421 else { 4422 for (; sa < ea; sa += DEV_BSIZE, j++) { 4423 if ((bp->b_pages[i]->valid & (1 << j)) == 0) { 4424 pmap_zero_page_area(bp->b_pages[i], 4425 sa, DEV_BSIZE); 4426 } 4427 } 4428 } 4429 bp->b_pages[i]->valid |= mask; 4430 } 4431 unlock: 4432 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 4433 bp->b_resid = 0; 4434 } 4435 4436 void 4437 vfs_bio_bzero_buf(struct buf *bp, int base, int size) 4438 { 4439 vm_page_t m; 4440 int i, n; 4441 4442 if (buf_mapped(bp)) { 4443 BUF_CHECK_MAPPED(bp); 4444 bzero(bp->b_data + base, size); 4445 } else { 4446 BUF_CHECK_UNMAPPED(bp); 4447 n = PAGE_SIZE - (base & PAGE_MASK); 4448 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 4449 m = bp->b_pages[i]; 4450 if (n > size) 4451 n = size; 4452 pmap_zero_page_area(m, base & PAGE_MASK, n); 4453 base += n; 4454 size -= n; 4455 n = PAGE_SIZE; 4456 } 4457 } 4458 } 4459 4460 /* 4461 * Update buffer flags based on I/O request parameters, optionally releasing the 4462 * buffer. If it's VMIO or direct I/O, the buffer pages are released to the VM, 4463 * where they may be placed on a page queue (VMIO) or freed immediately (direct 4464 * I/O). Otherwise the buffer is released to the cache. 4465 */ 4466 static void 4467 b_io_dismiss(struct buf *bp, int ioflag, bool release) 4468 { 4469 4470 KASSERT((ioflag & IO_NOREUSE) == 0 || (ioflag & IO_VMIO) != 0, 4471 ("buf %p non-VMIO noreuse", bp)); 4472 4473 if ((ioflag & IO_DIRECT) != 0) 4474 bp->b_flags |= B_DIRECT; 4475 if ((ioflag & (IO_VMIO | IO_DIRECT)) != 0 && LIST_EMPTY(&bp->b_dep)) { 4476 bp->b_flags |= B_RELBUF; 4477 if ((ioflag & IO_NOREUSE) != 0) 4478 bp->b_flags |= B_NOREUSE; 4479 if (release) 4480 brelse(bp); 4481 } else if (release) 4482 bqrelse(bp); 4483 } 4484 4485 void 4486 vfs_bio_brelse(struct buf *bp, int ioflag) 4487 { 4488 4489 b_io_dismiss(bp, ioflag, true); 4490 } 4491 4492 void 4493 vfs_bio_set_flags(struct buf *bp, int ioflag) 4494 { 4495 4496 b_io_dismiss(bp, ioflag, false); 4497 } 4498 4499 /* 4500 * vm_hold_load_pages and vm_hold_free_pages get pages into 4501 * a buffers address space. The pages are anonymous and are 4502 * not associated with a file object. 4503 */ 4504 static void 4505 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4506 { 4507 vm_offset_t pg; 4508 vm_page_t p; 4509 int index; 4510 4511 BUF_CHECK_MAPPED(bp); 4512 4513 to = round_page(to); 4514 from = round_page(from); 4515 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4516 4517 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 4518 tryagain: 4519 /* 4520 * note: must allocate system pages since blocking here 4521 * could interfere with paging I/O, no matter which 4522 * process we are. 4523 */ 4524 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ | 4525 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT)); 4526 if (p == NULL) { 4527 VM_WAIT; 4528 goto tryagain; 4529 } 4530 pmap_qenter(pg, &p, 1); 4531 bp->b_pages[index] = p; 4532 } 4533 bp->b_npages = index; 4534 } 4535 4536 /* Return pages associated with this buf to the vm system */ 4537 static void 4538 vm_hold_free_pages(struct buf *bp, int newbsize) 4539 { 4540 vm_offset_t from; 4541 vm_page_t p; 4542 int index, newnpages; 4543 4544 BUF_CHECK_MAPPED(bp); 4545 4546 from = round_page((vm_offset_t)bp->b_data + newbsize); 4547 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4548 if (bp->b_npages > newnpages) 4549 pmap_qremove(from, bp->b_npages - newnpages); 4550 for (index = newnpages; index < bp->b_npages; index++) { 4551 p = bp->b_pages[index]; 4552 bp->b_pages[index] = NULL; 4553 p->wire_count--; 4554 vm_page_free(p); 4555 } 4556 atomic_subtract_int(&vm_cnt.v_wire_count, bp->b_npages - newnpages); 4557 bp->b_npages = newnpages; 4558 } 4559 4560 /* 4561 * Map an IO request into kernel virtual address space. 4562 * 4563 * All requests are (re)mapped into kernel VA space. 4564 * Notice that we use b_bufsize for the size of the buffer 4565 * to be mapped. b_bcount might be modified by the driver. 4566 * 4567 * Note that even if the caller determines that the address space should 4568 * be valid, a race or a smaller-file mapped into a larger space may 4569 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 4570 * check the return value. 4571 * 4572 * This function only works with pager buffers. 4573 */ 4574 int 4575 vmapbuf(struct buf *bp, int mapbuf) 4576 { 4577 vm_prot_t prot; 4578 int pidx; 4579 4580 if (bp->b_bufsize < 0) 4581 return (-1); 4582 prot = VM_PROT_READ; 4583 if (bp->b_iocmd == BIO_READ) 4584 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 4585 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 4586 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages, 4587 btoc(MAXPHYS))) < 0) 4588 return (-1); 4589 bp->b_npages = pidx; 4590 bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK; 4591 if (mapbuf || !unmapped_buf_allowed) { 4592 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_pages, pidx); 4593 bp->b_data = bp->b_kvabase + bp->b_offset; 4594 } else 4595 bp->b_data = unmapped_buf; 4596 return(0); 4597 } 4598 4599 /* 4600 * Free the io map PTEs associated with this IO operation. 4601 * We also invalidate the TLB entries and restore the original b_addr. 4602 * 4603 * This function only works with pager buffers. 4604 */ 4605 void 4606 vunmapbuf(struct buf *bp) 4607 { 4608 int npages; 4609 4610 npages = bp->b_npages; 4611 if (buf_mapped(bp)) 4612 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 4613 vm_page_unhold_pages(bp->b_pages, npages); 4614 4615 bp->b_data = unmapped_buf; 4616 } 4617 4618 void 4619 bdone(struct buf *bp) 4620 { 4621 struct mtx *mtxp; 4622 4623 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4624 mtx_lock(mtxp); 4625 bp->b_flags |= B_DONE; 4626 wakeup(bp); 4627 mtx_unlock(mtxp); 4628 } 4629 4630 void 4631 bwait(struct buf *bp, u_char pri, const char *wchan) 4632 { 4633 struct mtx *mtxp; 4634 4635 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4636 mtx_lock(mtxp); 4637 while ((bp->b_flags & B_DONE) == 0) 4638 msleep(bp, mtxp, pri, wchan, 0); 4639 mtx_unlock(mtxp); 4640 } 4641 4642 int 4643 bufsync(struct bufobj *bo, int waitfor) 4644 { 4645 4646 return (VOP_FSYNC(bo2vnode(bo), waitfor, curthread)); 4647 } 4648 4649 void 4650 bufstrategy(struct bufobj *bo, struct buf *bp) 4651 { 4652 int i = 0; 4653 struct vnode *vp; 4654 4655 vp = bp->b_vp; 4656 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 4657 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 4658 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 4659 i = VOP_STRATEGY(vp, bp); 4660 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 4661 } 4662 4663 void 4664 bufobj_wrefl(struct bufobj *bo) 4665 { 4666 4667 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4668 ASSERT_BO_WLOCKED(bo); 4669 bo->bo_numoutput++; 4670 } 4671 4672 void 4673 bufobj_wref(struct bufobj *bo) 4674 { 4675 4676 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 4677 BO_LOCK(bo); 4678 bo->bo_numoutput++; 4679 BO_UNLOCK(bo); 4680 } 4681 4682 void 4683 bufobj_wdrop(struct bufobj *bo) 4684 { 4685 4686 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 4687 BO_LOCK(bo); 4688 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 4689 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 4690 bo->bo_flag &= ~BO_WWAIT; 4691 wakeup(&bo->bo_numoutput); 4692 } 4693 BO_UNLOCK(bo); 4694 } 4695 4696 int 4697 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 4698 { 4699 int error; 4700 4701 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 4702 ASSERT_BO_WLOCKED(bo); 4703 error = 0; 4704 while (bo->bo_numoutput) { 4705 bo->bo_flag |= BO_WWAIT; 4706 error = msleep(&bo->bo_numoutput, BO_LOCKPTR(bo), 4707 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 4708 if (error) 4709 break; 4710 } 4711 return (error); 4712 } 4713 4714 /* 4715 * Set bio_data or bio_ma for struct bio from the struct buf. 4716 */ 4717 void 4718 bdata2bio(struct buf *bp, struct bio *bip) 4719 { 4720 4721 if (!buf_mapped(bp)) { 4722 KASSERT(unmapped_buf_allowed, ("unmapped")); 4723 bip->bio_ma = bp->b_pages; 4724 bip->bio_ma_n = bp->b_npages; 4725 bip->bio_data = unmapped_buf; 4726 bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK; 4727 bip->bio_flags |= BIO_UNMAPPED; 4728 KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) / 4729 PAGE_SIZE == bp->b_npages, 4730 ("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset, 4731 (long long)bip->bio_length, bip->bio_ma_n)); 4732 } else { 4733 bip->bio_data = bp->b_data; 4734 bip->bio_ma = NULL; 4735 } 4736 } 4737 4738 /* 4739 * The MIPS pmap code currently doesn't handle aliased pages. 4740 * The VIPT caches may not handle page aliasing themselves, leading 4741 * to data corruption. 4742 * 4743 * As such, this code makes a system extremely unhappy if said 4744 * system doesn't support unaliasing the above situation in hardware. 4745 * Some "recent" systems (eg some mips24k/mips74k cores) don't enable 4746 * this feature at build time, so it has to be handled in software. 4747 * 4748 * Once the MIPS pmap/cache code grows to support this function on 4749 * earlier chips, it should be flipped back off. 4750 */ 4751 #ifdef __mips__ 4752 static int buf_pager_relbuf = 1; 4753 #else 4754 static int buf_pager_relbuf = 0; 4755 #endif 4756 SYSCTL_INT(_vfs, OID_AUTO, buf_pager_relbuf, CTLFLAG_RWTUN, 4757 &buf_pager_relbuf, 0, 4758 "Make buffer pager release buffers after reading"); 4759 4760 /* 4761 * The buffer pager. It uses buffer reads to validate pages. 4762 * 4763 * In contrast to the generic local pager from vm/vnode_pager.c, this 4764 * pager correctly and easily handles volumes where the underlying 4765 * device block size is greater than the machine page size. The 4766 * buffer cache transparently extends the requested page run to be 4767 * aligned at the block boundary, and does the necessary bogus page 4768 * replacements in the addends to avoid obliterating already valid 4769 * pages. 4770 * 4771 * The only non-trivial issue is that the exclusive busy state for 4772 * pages, which is assumed by the vm_pager_getpages() interface, is 4773 * incompatible with the VMIO buffer cache's desire to share-busy the 4774 * pages. This function performs a trivial downgrade of the pages' 4775 * state before reading buffers, and a less trivial upgrade from the 4776 * shared-busy to excl-busy state after the read. 4777 */ 4778 int 4779 vfs_bio_getpages(struct vnode *vp, vm_page_t *ma, int count, 4780 int *rbehind, int *rahead, vbg_get_lblkno_t get_lblkno, 4781 vbg_get_blksize_t get_blksize) 4782 { 4783 vm_page_t m; 4784 vm_object_t object; 4785 struct buf *bp; 4786 struct mount *mp; 4787 daddr_t lbn, lbnp; 4788 vm_ooffset_t la, lb, poff, poffe; 4789 long bsize; 4790 int bo_bs, br_flags, error, i, pgsin, pgsin_a, pgsin_b; 4791 bool redo, lpart; 4792 4793 object = vp->v_object; 4794 mp = vp->v_mount; 4795 la = IDX_TO_OFF(ma[count - 1]->pindex); 4796 if (la >= object->un_pager.vnp.vnp_size) 4797 return (VM_PAGER_BAD); 4798 lpart = la + PAGE_SIZE > object->un_pager.vnp.vnp_size; 4799 bo_bs = get_blksize(vp, get_lblkno(vp, IDX_TO_OFF(ma[0]->pindex))); 4800 4801 /* 4802 * Calculate read-ahead, behind and total pages. 4803 */ 4804 pgsin = count; 4805 lb = IDX_TO_OFF(ma[0]->pindex); 4806 pgsin_b = OFF_TO_IDX(lb - rounddown2(lb, bo_bs)); 4807 pgsin += pgsin_b; 4808 if (rbehind != NULL) 4809 *rbehind = pgsin_b; 4810 pgsin_a = OFF_TO_IDX(roundup2(la, bo_bs) - la); 4811 if (la + IDX_TO_OFF(pgsin_a) >= object->un_pager.vnp.vnp_size) 4812 pgsin_a = OFF_TO_IDX(roundup2(object->un_pager.vnp.vnp_size, 4813 PAGE_SIZE) - la); 4814 pgsin += pgsin_a; 4815 if (rahead != NULL) 4816 *rahead = pgsin_a; 4817 VM_CNT_INC(v_vnodein); 4818 VM_CNT_ADD(v_vnodepgsin, pgsin); 4819 4820 br_flags = (mp != NULL && (mp->mnt_kern_flag & MNTK_UNMAPPED_BUFS) 4821 != 0) ? GB_UNMAPPED : 0; 4822 VM_OBJECT_WLOCK(object); 4823 again: 4824 for (i = 0; i < count; i++) 4825 vm_page_busy_downgrade(ma[i]); 4826 VM_OBJECT_WUNLOCK(object); 4827 4828 lbnp = -1; 4829 for (i = 0; i < count; i++) { 4830 m = ma[i]; 4831 4832 /* 4833 * Pages are shared busy and the object lock is not 4834 * owned, which together allow for the pages' 4835 * invalidation. The racy test for validity avoids 4836 * useless creation of the buffer for the most typical 4837 * case when invalidation is not used in redo or for 4838 * parallel read. The shared->excl upgrade loop at 4839 * the end of the function catches the race in a 4840 * reliable way (protected by the object lock). 4841 */ 4842 if (m->valid == VM_PAGE_BITS_ALL) 4843 continue; 4844 4845 poff = IDX_TO_OFF(m->pindex); 4846 poffe = MIN(poff + PAGE_SIZE, object->un_pager.vnp.vnp_size); 4847 for (; poff < poffe; poff += bsize) { 4848 lbn = get_lblkno(vp, poff); 4849 if (lbn == lbnp) 4850 goto next_page; 4851 lbnp = lbn; 4852 4853 bsize = get_blksize(vp, lbn); 4854 error = bread_gb(vp, lbn, bsize, curthread->td_ucred, 4855 br_flags, &bp); 4856 if (error != 0) 4857 goto end_pages; 4858 if (LIST_EMPTY(&bp->b_dep)) { 4859 /* 4860 * Invalidation clears m->valid, but 4861 * may leave B_CACHE flag if the 4862 * buffer existed at the invalidation 4863 * time. In this case, recycle the 4864 * buffer to do real read on next 4865 * bread() after redo. 4866 * 4867 * Otherwise B_RELBUF is not strictly 4868 * necessary, enable to reduce buf 4869 * cache pressure. 4870 */ 4871 if (buf_pager_relbuf || 4872 m->valid != VM_PAGE_BITS_ALL) 4873 bp->b_flags |= B_RELBUF; 4874 4875 bp->b_flags &= ~B_NOCACHE; 4876 brelse(bp); 4877 } else { 4878 bqrelse(bp); 4879 } 4880 } 4881 KASSERT(1 /* racy, enable for debugging */ || 4882 m->valid == VM_PAGE_BITS_ALL || i == count - 1, 4883 ("buf %d %p invalid", i, m)); 4884 if (i == count - 1 && lpart) { 4885 VM_OBJECT_WLOCK(object); 4886 if (m->valid != 0 && 4887 m->valid != VM_PAGE_BITS_ALL) 4888 vm_page_zero_invalid(m, TRUE); 4889 VM_OBJECT_WUNLOCK(object); 4890 } 4891 next_page:; 4892 } 4893 end_pages: 4894 4895 VM_OBJECT_WLOCK(object); 4896 redo = false; 4897 for (i = 0; i < count; i++) { 4898 vm_page_sunbusy(ma[i]); 4899 ma[i] = vm_page_grab(object, ma[i]->pindex, VM_ALLOC_NORMAL); 4900 4901 /* 4902 * Since the pages were only sbusy while neither the 4903 * buffer nor the object lock was held by us, or 4904 * reallocated while vm_page_grab() slept for busy 4905 * relinguish, they could have been invalidated. 4906 * Recheck the valid bits and re-read as needed. 4907 * 4908 * Note that the last page is made fully valid in the 4909 * read loop, and partial validity for the page at 4910 * index count - 1 could mean that the page was 4911 * invalidated or removed, so we must restart for 4912 * safety as well. 4913 */ 4914 if (ma[i]->valid != VM_PAGE_BITS_ALL) 4915 redo = true; 4916 } 4917 if (redo && error == 0) 4918 goto again; 4919 VM_OBJECT_WUNLOCK(object); 4920 return (error != 0 ? VM_PAGER_ERROR : VM_PAGER_OK); 4921 } 4922 4923 #include "opt_ddb.h" 4924 #ifdef DDB 4925 #include <ddb/ddb.h> 4926 4927 /* DDB command to show buffer data */ 4928 DB_SHOW_COMMAND(buffer, db_show_buffer) 4929 { 4930 /* get args */ 4931 struct buf *bp = (struct buf *)addr; 4932 #ifdef FULL_BUF_TRACKING 4933 uint32_t i, j; 4934 #endif 4935 4936 if (!have_addr) { 4937 db_printf("usage: show buffer <addr>\n"); 4938 return; 4939 } 4940 4941 db_printf("buf at %p\n", bp); 4942 db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n", 4943 (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags, 4944 PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS); 4945 db_printf( 4946 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 4947 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, " 4948 "b_dep = %p\n", 4949 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 4950 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 4951 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first); 4952 db_printf("b_kvabase = %p, b_kvasize = %d\n", 4953 bp->b_kvabase, bp->b_kvasize); 4954 if (bp->b_npages) { 4955 int i; 4956 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 4957 for (i = 0; i < bp->b_npages; i++) { 4958 vm_page_t m; 4959 m = bp->b_pages[i]; 4960 if (m != NULL) 4961 db_printf("(%p, 0x%lx, 0x%lx)", m->object, 4962 (u_long)m->pindex, 4963 (u_long)VM_PAGE_TO_PHYS(m)); 4964 else 4965 db_printf("( ??? )"); 4966 if ((i + 1) < bp->b_npages) 4967 db_printf(","); 4968 } 4969 db_printf("\n"); 4970 } 4971 #if defined(FULL_BUF_TRACKING) 4972 db_printf("b_io_tracking: b_io_tcnt = %u\n", bp->b_io_tcnt); 4973 4974 i = bp->b_io_tcnt % BUF_TRACKING_SIZE; 4975 for (j = 1; j <= BUF_TRACKING_SIZE; j++) { 4976 if (bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)] == NULL) 4977 continue; 4978 db_printf(" %2u: %s\n", j, 4979 bp->b_io_tracking[BUF_TRACKING_ENTRY(i - j)]); 4980 } 4981 #elif defined(BUF_TRACKING) 4982 db_printf("b_io_tracking: %s\n", bp->b_io_tracking); 4983 #endif 4984 db_printf(" "); 4985 BUF_LOCKPRINTINFO(bp); 4986 } 4987 4988 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 4989 { 4990 struct buf *bp; 4991 int i; 4992 4993 for (i = 0; i < nbuf; i++) { 4994 bp = &buf[i]; 4995 if (BUF_ISLOCKED(bp)) { 4996 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4997 db_printf("\n"); 4998 if (db_pager_quit) 4999 break; 5000 } 5001 } 5002 } 5003 5004 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 5005 { 5006 struct vnode *vp; 5007 struct buf *bp; 5008 5009 if (!have_addr) { 5010 db_printf("usage: show vnodebufs <addr>\n"); 5011 return; 5012 } 5013 vp = (struct vnode *)addr; 5014 db_printf("Clean buffers:\n"); 5015 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 5016 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 5017 db_printf("\n"); 5018 } 5019 db_printf("Dirty buffers:\n"); 5020 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 5021 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 5022 db_printf("\n"); 5023 } 5024 } 5025 5026 DB_COMMAND(countfreebufs, db_coundfreebufs) 5027 { 5028 struct buf *bp; 5029 int i, used = 0, nfree = 0; 5030 5031 if (have_addr) { 5032 db_printf("usage: countfreebufs\n"); 5033 return; 5034 } 5035 5036 for (i = 0; i < nbuf; i++) { 5037 bp = &buf[i]; 5038 if (bp->b_qindex == QUEUE_EMPTY) 5039 nfree++; 5040 else 5041 used++; 5042 } 5043 5044 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 5045 nfree + used); 5046 db_printf("numfreebuffers is %d\n", numfreebuffers); 5047 } 5048 #endif /* DDB */ 5049