1 /* 2 * Copyright (c) 1994,1997 John S. Dyson 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice immediately at the beginning of the file, without modification, 10 * this list of conditions, and the following disclaimer. 11 * 2. Absolutely no warranty of function or purpose is made by the author 12 * John S. Dyson. 13 * 14 * $FreeBSD: src/sys/kern/vfs_bio.c,v 1.242.2.20 2003/05/28 18:38:10 alc Exp $ 15 */ 16 17 /* 18 * this file contains a new buffer I/O scheme implementing a coherent 19 * VM object and buffer cache scheme. Pains have been taken to make 20 * sure that the performance degradation associated with schemes such 21 * as this is not realized. 22 * 23 * Author: John S. Dyson 24 * Significant help during the development and debugging phases 25 * had been provided by David Greenman, also of the FreeBSD core team. 26 * 27 * see man buf(9) for more info. Note that man buf(9) doesn't reflect 28 * the actual buf/bio implementation in DragonFly. 29 */ 30 31 #include <sys/param.h> 32 #include <sys/systm.h> 33 #include <sys/buf.h> 34 #include <sys/conf.h> 35 #include <sys/devicestat.h> 36 #include <sys/eventhandler.h> 37 #include <sys/lock.h> 38 #include <sys/malloc.h> 39 #include <sys/mount.h> 40 #include <sys/kernel.h> 41 #include <sys/kthread.h> 42 #include <sys/proc.h> 43 #include <sys/reboot.h> 44 #include <sys/resourcevar.h> 45 #include <sys/sysctl.h> 46 #include <sys/vmmeter.h> 47 #include <sys/vnode.h> 48 #include <sys/dsched.h> 49 #include <vm/vm.h> 50 #include <vm/vm_param.h> 51 #include <vm/vm_kern.h> 52 #include <vm/vm_pageout.h> 53 #include <vm/vm_page.h> 54 #include <vm/vm_object.h> 55 #include <vm/vm_extern.h> 56 #include <vm/vm_map.h> 57 #include <vm/vm_pager.h> 58 #include <vm/swap_pager.h> 59 60 #include <sys/buf2.h> 61 #include <sys/spinlock2.h> 62 #include <vm/vm_page2.h> 63 64 #include "opt_ddb.h" 65 #ifdef DDB 66 #include <ddb/ddb.h> 67 #endif 68 69 /* 70 * Buffer queues. 71 */ 72 enum bufq_type { 73 BQUEUE_NONE, /* not on any queue */ 74 BQUEUE_LOCKED, /* locked buffers */ 75 BQUEUE_CLEAN, /* non-B_DELWRI buffers */ 76 BQUEUE_DIRTY, /* B_DELWRI buffers */ 77 BQUEUE_DIRTY_HW, /* B_DELWRI buffers - heavy weight */ 78 BQUEUE_EMPTY, /* empty buffer headers */ 79 80 BUFFER_QUEUES /* number of buffer queues */ 81 }; 82 83 typedef enum bufq_type bufq_type_t; 84 85 #define BD_WAKE_SIZE 16384 86 #define BD_WAKE_MASK (BD_WAKE_SIZE - 1) 87 88 TAILQ_HEAD(bqueues, buf); 89 90 struct bufpcpu { 91 struct spinlock spin; 92 struct bqueues bufqueues[BUFFER_QUEUES]; 93 } __cachealign; 94 95 struct bufpcpu bufpcpu[MAXCPU]; 96 97 static MALLOC_DEFINE(M_BIOBUF, "BIO buffer", "BIO buffer"); 98 99 struct buf *buf; /* buffer header pool */ 100 101 static void vfs_clean_pages(struct buf *bp); 102 static void vfs_clean_one_page(struct buf *bp, int pageno, vm_page_t m); 103 #if 0 104 static void vfs_dirty_one_page(struct buf *bp, int pageno, vm_page_t m); 105 #endif 106 static void vfs_vmio_release(struct buf *bp); 107 static int flushbufqueues(struct buf *marker, bufq_type_t q); 108 static vm_page_t bio_page_alloc(struct buf *bp, vm_object_t obj, 109 vm_pindex_t pg, int deficit); 110 111 static void bd_signal(long totalspace); 112 static void buf_daemon(void); 113 static void buf_daemon_hw(void); 114 115 /* 116 * bogus page -- for I/O to/from partially complete buffers 117 * this is a temporary solution to the problem, but it is not 118 * really that bad. it would be better to split the buffer 119 * for input in the case of buffers partially already in memory, 120 * but the code is intricate enough already. 121 */ 122 vm_page_t bogus_page; 123 124 /* 125 * These are all static, but make the ones we export globals so we do 126 * not need to use compiler magic. 127 */ 128 long bufspace; /* atomic ops */ 129 long maxbufspace; 130 long maxbufmallocspace, lobufspace, hibufspace; 131 static long lorunningspace; 132 static long hirunningspace; 133 static long dirtykvaspace; /* atomic */ 134 long dirtybufspace; /* atomic (global for systat) */ 135 static long dirtybufcount; /* atomic */ 136 static long dirtybufspacehw; /* atomic */ 137 static long dirtybufcounthw; /* atomic */ 138 static long runningbufspace; /* atomic */ 139 static long runningbufcount; /* atomic */ 140 long lodirtybufspace; 141 long hidirtybufspace; 142 static int getnewbufcalls; 143 static int needsbuffer; /* atomic */ 144 static int runningbufreq; /* atomic */ 145 static int bd_request; /* atomic */ 146 static int bd_request_hw; /* atomic */ 147 static u_int bd_wake_ary[BD_WAKE_SIZE]; 148 static u_int bd_wake_index; 149 static u_int vm_cycle_point = 40; /* 23-36 will migrate more act->inact */ 150 static int debug_commit; 151 static int debug_bufbio; 152 static int debug_kvabio; 153 static long bufcache_bw = 200 * 1024 * 1024; 154 155 static struct thread *bufdaemon_td; 156 static struct thread *bufdaemonhw_td; 157 static u_int lowmempgallocs; 158 static u_int flushperqueue = 1024; 159 160 /* 161 * Sysctls for operational control of the buffer cache. 162 */ 163 SYSCTL_UINT(_vfs, OID_AUTO, flushperqueue, CTLFLAG_RW, &flushperqueue, 0, 164 "Number of buffers to flush from each per-cpu queue"); 165 SYSCTL_LONG(_vfs, OID_AUTO, lodirtybufspace, CTLFLAG_RW, &lodirtybufspace, 0, 166 "Number of dirty buffers to flush before bufdaemon becomes inactive"); 167 SYSCTL_LONG(_vfs, OID_AUTO, hidirtybufspace, CTLFLAG_RW, &hidirtybufspace, 0, 168 "High watermark used to trigger explicit flushing of dirty buffers"); 169 SYSCTL_LONG(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0, 170 "Minimum amount of buffer space required for active I/O"); 171 SYSCTL_LONG(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0, 172 "Maximum amount of buffer space to usable for active I/O"); 173 SYSCTL_LONG(_vfs, OID_AUTO, bufcache_bw, CTLFLAG_RW, &bufcache_bw, 0, 174 "Buffer-cache -> VM page cache transfer bandwidth"); 175 SYSCTL_UINT(_vfs, OID_AUTO, lowmempgallocs, CTLFLAG_RW, &lowmempgallocs, 0, 176 "Page allocations done during periods of very low free memory"); 177 SYSCTL_UINT(_vfs, OID_AUTO, vm_cycle_point, CTLFLAG_RW, &vm_cycle_point, 0, 178 "Recycle pages to active or inactive queue transition pt 0-64"); 179 /* 180 * Sysctls determining current state of the buffer cache. 181 */ 182 SYSCTL_LONG(_vfs, OID_AUTO, nbuf, CTLFLAG_RD, &nbuf, 0, 183 "Total number of buffers in buffer cache"); 184 SYSCTL_LONG(_vfs, OID_AUTO, dirtykvaspace, CTLFLAG_RD, &dirtykvaspace, 0, 185 "KVA reserved by dirty buffers (all)"); 186 SYSCTL_LONG(_vfs, OID_AUTO, dirtybufspace, CTLFLAG_RD, &dirtybufspace, 0, 187 "Pending bytes of dirty buffers (all)"); 188 SYSCTL_LONG(_vfs, OID_AUTO, dirtybufspacehw, CTLFLAG_RD, &dirtybufspacehw, 0, 189 "Pending bytes of dirty buffers (heavy weight)"); 190 SYSCTL_LONG(_vfs, OID_AUTO, dirtybufcount, CTLFLAG_RD, &dirtybufcount, 0, 191 "Pending number of dirty buffers"); 192 SYSCTL_LONG(_vfs, OID_AUTO, dirtybufcounthw, CTLFLAG_RD, &dirtybufcounthw, 0, 193 "Pending number of dirty buffers (heavy weight)"); 194 SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 195 "I/O bytes currently in progress due to asynchronous writes"); 196 SYSCTL_LONG(_vfs, OID_AUTO, runningbufcount, CTLFLAG_RD, &runningbufcount, 0, 197 "I/O buffers currently in progress due to asynchronous writes"); 198 SYSCTL_LONG(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0, 199 "Hard limit on maximum amount of memory usable for buffer space"); 200 SYSCTL_LONG(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0, 201 "Soft limit on maximum amount of memory usable for buffer space"); 202 SYSCTL_LONG(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0, 203 "Minimum amount of memory to reserve for system buffer space"); 204 SYSCTL_LONG(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, 205 "Amount of memory available for buffers"); 206 SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RD, &maxbufmallocspace, 207 0, "Maximum amount of memory reserved for buffers using malloc"); 208 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RD, &getnewbufcalls, 0, 209 "New buffer header acquisition requests"); 210 SYSCTL_INT(_vfs, OID_AUTO, debug_commit, CTLFLAG_RW, &debug_commit, 0, ""); 211 SYSCTL_INT(_vfs, OID_AUTO, debug_bufbio, CTLFLAG_RW, &debug_bufbio, 0, ""); 212 SYSCTL_INT(_vfs, OID_AUTO, debug_kvabio, CTLFLAG_RW, &debug_kvabio, 0, ""); 213 SYSCTL_INT(_debug_sizeof, OID_AUTO, buf, CTLFLAG_RD, 0, sizeof(struct buf), 214 "sizeof(struct buf)"); 215 216 char *buf_wmesg = BUF_WMESG; 217 218 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 219 #define VFS_BIO_NEED_UNUSED02 0x02 220 #define VFS_BIO_NEED_UNUSED04 0x04 221 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 222 223 /* 224 * Called when buffer space is potentially available for recovery. 225 * getnewbuf() will block on this flag when it is unable to free 226 * sufficient buffer space. Buffer space becomes recoverable when 227 * bp's get placed back in the queues. 228 */ 229 static __inline void 230 bufspacewakeup(void) 231 { 232 /* 233 * If someone is waiting for BUF space, wake them up. Even 234 * though we haven't freed the kva space yet, the waiting 235 * process will be able to now. 236 */ 237 for (;;) { 238 int flags = needsbuffer; 239 cpu_ccfence(); 240 if ((flags & VFS_BIO_NEED_BUFSPACE) == 0) 241 break; 242 if (atomic_cmpset_int(&needsbuffer, flags, 243 flags & ~VFS_BIO_NEED_BUFSPACE)) { 244 wakeup(&needsbuffer); 245 break; 246 } 247 /* retry */ 248 } 249 } 250 251 /* 252 * runningbufwakeup: 253 * 254 * Accounting for I/O in progress. 255 * 256 */ 257 static __inline void 258 runningbufwakeup(struct buf *bp) 259 { 260 long totalspace; 261 long flags; 262 263 if ((totalspace = bp->b_runningbufspace) != 0) { 264 atomic_add_long(&runningbufspace, -totalspace); 265 atomic_add_long(&runningbufcount, -1); 266 bp->b_runningbufspace = 0; 267 268 /* 269 * see waitrunningbufspace() for limit test. 270 */ 271 for (;;) { 272 flags = runningbufreq; 273 cpu_ccfence(); 274 if (flags == 0) 275 break; 276 if (atomic_cmpset_int(&runningbufreq, flags, 0)) { 277 wakeup(&runningbufreq); 278 break; 279 } 280 /* retry */ 281 } 282 bd_signal(totalspace); 283 } 284 } 285 286 /* 287 * bufcountwakeup: 288 * 289 * Called when a buffer has been added to one of the free queues to 290 * account for the buffer and to wakeup anyone waiting for free buffers. 291 * This typically occurs when large amounts of metadata are being handled 292 * by the buffer cache ( else buffer space runs out first, usually ). 293 */ 294 static __inline void 295 bufcountwakeup(void) 296 { 297 long flags; 298 299 for (;;) { 300 flags = needsbuffer; 301 if (flags == 0) 302 break; 303 if (atomic_cmpset_int(&needsbuffer, flags, 304 (flags & ~VFS_BIO_NEED_ANY))) { 305 wakeup(&needsbuffer); 306 break; 307 } 308 /* retry */ 309 } 310 } 311 312 /* 313 * waitrunningbufspace() 314 * 315 * If runningbufspace exceeds 4/6 hirunningspace we block until 316 * runningbufspace drops to 3/6 hirunningspace. We also block if another 317 * thread blocked here in order to be fair, even if runningbufspace 318 * is now lower than the limit. 319 * 320 * The caller may be using this function to block in a tight loop, we 321 * must block while runningbufspace is greater than at least 322 * hirunningspace * 3 / 6. 323 */ 324 void 325 waitrunningbufspace(void) 326 { 327 long limit = hirunningspace * 4 / 6; 328 long flags; 329 330 while (runningbufspace > limit || runningbufreq) { 331 tsleep_interlock(&runningbufreq, 0); 332 flags = atomic_fetchadd_int(&runningbufreq, 1); 333 if (runningbufspace > limit || flags) 334 tsleep(&runningbufreq, PINTERLOCKED, "wdrn1", hz); 335 } 336 } 337 338 /* 339 * buf_dirty_count_severe: 340 * 341 * Return true if we have too many dirty buffers. 342 */ 343 int 344 buf_dirty_count_severe(void) 345 { 346 return (runningbufspace + dirtykvaspace >= hidirtybufspace || 347 dirtybufcount >= nbuf / 2); 348 } 349 350 /* 351 * Return true if the amount of running I/O is severe and BIOQ should 352 * start bursting. 353 */ 354 int 355 buf_runningbufspace_severe(void) 356 { 357 return (runningbufspace >= hirunningspace * 4 / 6); 358 } 359 360 /* 361 * vfs_buf_test_cache: 362 * 363 * Called when a buffer is extended. This function clears the B_CACHE 364 * bit if the newly extended portion of the buffer does not contain 365 * valid data. 366 * 367 * NOTE! Dirty VM pages are not processed into dirty (B_DELWRI) buffer 368 * cache buffers. The VM pages remain dirty, as someone had mmap()'d 369 * them while a clean buffer was present. 370 */ 371 static __inline__ 372 void 373 vfs_buf_test_cache(struct buf *bp, 374 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 375 vm_page_t m) 376 { 377 if (bp->b_flags & B_CACHE) { 378 int base = (foff + off) & PAGE_MASK; 379 if (vm_page_is_valid(m, base, size) == 0) 380 bp->b_flags &= ~B_CACHE; 381 } 382 } 383 384 /* 385 * bd_speedup() 386 * 387 * Spank the buf_daemon[_hw] if the total dirty buffer space exceeds the 388 * low water mark. 389 */ 390 static __inline__ 391 void 392 bd_speedup(void) 393 { 394 if (dirtykvaspace < lodirtybufspace && dirtybufcount < nbuf / 2) 395 return; 396 397 if (bd_request == 0 && 398 (dirtykvaspace > lodirtybufspace / 2 || 399 dirtybufcount - dirtybufcounthw >= nbuf / 2)) { 400 if (atomic_fetchadd_int(&bd_request, 1) == 0) 401 wakeup(&bd_request); 402 } 403 if (bd_request_hw == 0 && 404 (dirtykvaspace > lodirtybufspace / 2 || 405 dirtybufcounthw >= nbuf / 2)) { 406 if (atomic_fetchadd_int(&bd_request_hw, 1) == 0) 407 wakeup(&bd_request_hw); 408 } 409 } 410 411 /* 412 * bd_heatup() 413 * 414 * Get the buf_daemon heated up when the number of running and dirty 415 * buffers exceeds the mid-point. 416 * 417 * Return the total number of dirty bytes past the second mid point 418 * as a measure of how much excess dirty data there is in the system. 419 */ 420 long 421 bd_heatup(void) 422 { 423 long mid1; 424 long mid2; 425 long totalspace; 426 427 mid1 = lodirtybufspace + (hidirtybufspace - lodirtybufspace) / 2; 428 429 totalspace = runningbufspace + dirtykvaspace; 430 if (totalspace >= mid1 || dirtybufcount >= nbuf / 2) { 431 bd_speedup(); 432 mid2 = mid1 + (hidirtybufspace - mid1) / 2; 433 if (totalspace >= mid2) 434 return(totalspace - mid2); 435 } 436 return(0); 437 } 438 439 /* 440 * bd_wait() 441 * 442 * Wait for the buffer cache to flush (totalspace) bytes worth of 443 * buffers, then return. 444 * 445 * Regardless this function blocks while the number of dirty buffers 446 * exceeds hidirtybufspace. 447 */ 448 void 449 bd_wait(long totalspace) 450 { 451 u_int i; 452 u_int j; 453 u_int mi; 454 int count; 455 456 if (curthread == bufdaemonhw_td || curthread == bufdaemon_td) 457 return; 458 459 while (totalspace > 0) { 460 bd_heatup(); 461 462 /* 463 * Order is important. Suppliers adjust bd_wake_index after 464 * updating runningbufspace/dirtykvaspace. We want to fetch 465 * bd_wake_index before accessing. Any error should thus 466 * be in our favor. 467 */ 468 i = atomic_fetchadd_int(&bd_wake_index, 0); 469 if (totalspace > runningbufspace + dirtykvaspace) 470 totalspace = runningbufspace + dirtykvaspace; 471 count = totalspace / MAXBSIZE; 472 if (count >= BD_WAKE_SIZE / 2) 473 count = BD_WAKE_SIZE / 2; 474 i = i + count; 475 mi = i & BD_WAKE_MASK; 476 477 /* 478 * This is not a strict interlock, so we play a bit loose 479 * with locking access to dirtybufspace*. We have to re-check 480 * bd_wake_index to ensure that it hasn't passed us. 481 */ 482 tsleep_interlock(&bd_wake_ary[mi], 0); 483 atomic_add_int(&bd_wake_ary[mi], 1); 484 j = atomic_fetchadd_int(&bd_wake_index, 0); 485 if ((int)(i - j) >= 0) 486 tsleep(&bd_wake_ary[mi], PINTERLOCKED, "flstik", hz); 487 488 totalspace = runningbufspace + dirtykvaspace - hidirtybufspace; 489 } 490 } 491 492 /* 493 * bd_signal() 494 * 495 * This function is called whenever runningbufspace or dirtykvaspace 496 * is reduced. Track threads waiting for run+dirty buffer I/O 497 * complete. 498 */ 499 static void 500 bd_signal(long totalspace) 501 { 502 u_int i; 503 504 if (totalspace > 0) { 505 if (totalspace > MAXBSIZE * BD_WAKE_SIZE) 506 totalspace = MAXBSIZE * BD_WAKE_SIZE; 507 while (totalspace > 0) { 508 i = atomic_fetchadd_int(&bd_wake_index, 1); 509 i &= BD_WAKE_MASK; 510 if (atomic_readandclear_int(&bd_wake_ary[i])) 511 wakeup(&bd_wake_ary[i]); 512 totalspace -= MAXBSIZE; 513 } 514 } 515 } 516 517 /* 518 * BIO tracking support routines. 519 * 520 * Release a ref on a bio_track. Wakeup requests are atomically released 521 * along with the last reference so bk_active will never wind up set to 522 * only 0x80000000. 523 */ 524 static 525 void 526 bio_track_rel(struct bio_track *track) 527 { 528 int active; 529 int desired; 530 531 /* 532 * Shortcut 533 */ 534 active = track->bk_active; 535 if (active == 1 && atomic_cmpset_int(&track->bk_active, 1, 0)) 536 return; 537 538 /* 539 * Full-on. Note that the wait flag is only atomically released on 540 * the 1->0 count transition. 541 * 542 * We check for a negative count transition using bit 30 since bit 31 543 * has a different meaning. 544 */ 545 for (;;) { 546 desired = (active & 0x7FFFFFFF) - 1; 547 if (desired) 548 desired |= active & 0x80000000; 549 if (atomic_cmpset_int(&track->bk_active, active, desired)) { 550 if (desired & 0x40000000) 551 panic("bio_track_rel: bad count: %p", track); 552 if (active & 0x80000000) 553 wakeup(track); 554 break; 555 } 556 active = track->bk_active; 557 } 558 } 559 560 /* 561 * Wait for the tracking count to reach 0. 562 * 563 * Use atomic ops such that the wait flag is only set atomically when 564 * bk_active is non-zero. 565 */ 566 int 567 bio_track_wait(struct bio_track *track, int slp_flags, int slp_timo) 568 { 569 int active; 570 int desired; 571 int error; 572 573 /* 574 * Shortcut 575 */ 576 if (track->bk_active == 0) 577 return(0); 578 579 /* 580 * Full-on. Note that the wait flag may only be atomically set if 581 * the active count is non-zero. 582 * 583 * NOTE: We cannot optimize active == desired since a wakeup could 584 * clear active prior to our tsleep_interlock(). 585 */ 586 error = 0; 587 while ((active = track->bk_active) != 0) { 588 cpu_ccfence(); 589 desired = active | 0x80000000; 590 tsleep_interlock(track, slp_flags); 591 if (atomic_cmpset_int(&track->bk_active, active, desired)) { 592 error = tsleep(track, slp_flags | PINTERLOCKED, 593 "trwait", slp_timo); 594 if (error) 595 break; 596 } 597 } 598 return (error); 599 } 600 601 /* 602 * bufinit: 603 * 604 * Load time initialisation of the buffer cache, called from machine 605 * dependant initialization code. 606 */ 607 static 608 void 609 bufinit(void *dummy __unused) 610 { 611 struct bufpcpu *pcpu; 612 struct buf *bp; 613 vm_offset_t bogus_offset; 614 int i; 615 int j; 616 long n; 617 618 /* next, make a null set of free lists */ 619 for (i = 0; i < ncpus; ++i) { 620 pcpu = &bufpcpu[i]; 621 spin_init(&pcpu->spin, "bufinit"); 622 for (j = 0; j < BUFFER_QUEUES; j++) 623 TAILQ_INIT(&pcpu->bufqueues[j]); 624 } 625 626 /* 627 * Finally, initialize each buffer header and stick on empty q. 628 * Each buffer gets its own KVA reservation. 629 */ 630 i = 0; 631 pcpu = &bufpcpu[i]; 632 633 for (n = 0; n < nbuf; n++) { 634 bp = &buf[n]; 635 bzero(bp, sizeof *bp); 636 bp->b_flags = B_INVAL; /* we're just an empty header */ 637 bp->b_cmd = BUF_CMD_DONE; 638 bp->b_qindex = BQUEUE_EMPTY; 639 bp->b_qcpu = i; 640 bp->b_kvabase = (void *)(vm_map_min(&buffer_map) + 641 MAXBSIZE * n); 642 bp->b_kvasize = MAXBSIZE; 643 initbufbio(bp); 644 xio_init(&bp->b_xio); 645 buf_dep_init(bp); 646 TAILQ_INSERT_TAIL(&pcpu->bufqueues[bp->b_qindex], 647 bp, b_freelist); 648 649 i = (i + 1) % ncpus; 650 pcpu = &bufpcpu[i]; 651 } 652 653 /* 654 * maxbufspace is the absolute maximum amount of buffer space we are 655 * allowed to reserve in KVM and in real terms. The absolute maximum 656 * is nominally used by buf_daemon. hibufspace is the nominal maximum 657 * used by most other processes. The differential is required to 658 * ensure that buf_daemon is able to run when other processes might 659 * be blocked waiting for buffer space. 660 * 661 * Calculate hysteresis (lobufspace, hibufspace). Don't make it 662 * too large or we might lockup a cpu for too long a period of 663 * time in our tight loop. 664 */ 665 maxbufspace = nbuf * NBUFCALCSIZE; 666 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 667 lobufspace = hibufspace * 7 / 8; 668 if (hibufspace - lobufspace > 64 * 1024 * 1024) 669 lobufspace = hibufspace - 64 * 1024 * 1024; 670 if (lobufspace > hibufspace - MAXBSIZE) 671 lobufspace = hibufspace - MAXBSIZE; 672 673 lorunningspace = 512 * 1024; 674 /* hirunningspace -- see below */ 675 676 /* 677 * Limit the amount of malloc memory since it is wired permanently 678 * into the kernel space. Even though this is accounted for in 679 * the buffer allocation, we don't want the malloced region to grow 680 * uncontrolled. The malloc scheme improves memory utilization 681 * significantly on average (small) directories. 682 */ 683 maxbufmallocspace = hibufspace / 20; 684 685 /* 686 * Reduce the chance of a deadlock occuring by limiting the number 687 * of delayed-write dirty buffers we allow to stack up. 688 * 689 * We don't want too much actually queued to the device at once 690 * (XXX this needs to be per-mount!), because the buffers will 691 * wind up locked for a very long period of time while the I/O 692 * drains. 693 */ 694 hidirtybufspace = hibufspace / 2; /* dirty + running */ 695 hirunningspace = hibufspace / 16; /* locked & queued to device */ 696 if (hirunningspace < 1024 * 1024) 697 hirunningspace = 1024 * 1024; 698 699 dirtykvaspace = 0; 700 dirtybufspace = 0; 701 dirtybufspacehw = 0; 702 703 lodirtybufspace = hidirtybufspace / 2; 704 705 /* 706 * Maximum number of async ops initiated per buf_daemon loop. This is 707 * somewhat of a hack at the moment, we really need to limit ourselves 708 * based on the number of bytes of I/O in-transit that were initiated 709 * from buf_daemon. 710 */ 711 712 bogus_offset = kmem_alloc_pageable(&kernel_map, PAGE_SIZE, 713 VM_SUBSYS_BOGUS); 714 vm_object_hold(&kernel_object); 715 bogus_page = vm_page_alloc(&kernel_object, 716 (bogus_offset >> PAGE_SHIFT), 717 VM_ALLOC_NORMAL); 718 vm_object_drop(&kernel_object); 719 vmstats.v_wire_count++; 720 721 } 722 723 SYSINIT(do_bufinit, SI_BOOT2_MACHDEP, SI_ORDER_FIRST, bufinit, NULL); 724 725 /* 726 * Initialize the embedded bio structures, typically used by 727 * deprecated code which tries to allocate its own struct bufs. 728 */ 729 void 730 initbufbio(struct buf *bp) 731 { 732 bp->b_bio1.bio_buf = bp; 733 bp->b_bio1.bio_prev = NULL; 734 bp->b_bio1.bio_offset = NOOFFSET; 735 bp->b_bio1.bio_next = &bp->b_bio2; 736 bp->b_bio1.bio_done = NULL; 737 bp->b_bio1.bio_flags = 0; 738 739 bp->b_bio2.bio_buf = bp; 740 bp->b_bio2.bio_prev = &bp->b_bio1; 741 bp->b_bio2.bio_offset = NOOFFSET; 742 bp->b_bio2.bio_next = NULL; 743 bp->b_bio2.bio_done = NULL; 744 bp->b_bio2.bio_flags = 0; 745 746 BUF_LOCKINIT(bp); 747 } 748 749 /* 750 * Reinitialize the embedded bio structures as well as any additional 751 * translation cache layers. 752 */ 753 void 754 reinitbufbio(struct buf *bp) 755 { 756 struct bio *bio; 757 758 for (bio = &bp->b_bio1; bio; bio = bio->bio_next) { 759 bio->bio_done = NULL; 760 bio->bio_offset = NOOFFSET; 761 } 762 } 763 764 /* 765 * Undo the effects of an initbufbio(). 766 */ 767 void 768 uninitbufbio(struct buf *bp) 769 { 770 dsched_buf_exit(bp); 771 BUF_LOCKFREE(bp); 772 } 773 774 /* 775 * Push another BIO layer onto an existing BIO and return it. The new 776 * BIO layer may already exist, holding cached translation data. 777 */ 778 struct bio * 779 push_bio(struct bio *bio) 780 { 781 struct bio *nbio; 782 783 if ((nbio = bio->bio_next) == NULL) { 784 int index = bio - &bio->bio_buf->b_bio_array[0]; 785 if (index >= NBUF_BIO - 1) { 786 panic("push_bio: too many layers %d for bp %p", 787 index, bio->bio_buf); 788 } 789 nbio = &bio->bio_buf->b_bio_array[index + 1]; 790 bio->bio_next = nbio; 791 nbio->bio_prev = bio; 792 nbio->bio_buf = bio->bio_buf; 793 nbio->bio_offset = NOOFFSET; 794 nbio->bio_done = NULL; 795 nbio->bio_next = NULL; 796 } 797 KKASSERT(nbio->bio_done == NULL); 798 return(nbio); 799 } 800 801 /* 802 * Pop a BIO translation layer, returning the previous layer. The 803 * must have been previously pushed. 804 */ 805 struct bio * 806 pop_bio(struct bio *bio) 807 { 808 return(bio->bio_prev); 809 } 810 811 void 812 clearbiocache(struct bio *bio) 813 { 814 while (bio) { 815 bio->bio_offset = NOOFFSET; 816 bio = bio->bio_next; 817 } 818 } 819 820 /* 821 * Remove the buffer from the appropriate free list. 822 * (caller must be locked) 823 */ 824 static __inline void 825 _bremfree(struct buf *bp) 826 { 827 struct bufpcpu *pcpu = &bufpcpu[bp->b_qcpu]; 828 829 if (bp->b_qindex != BQUEUE_NONE) { 830 KASSERT(BUF_LOCKINUSE(bp), ("bremfree: bp %p not locked", bp)); 831 TAILQ_REMOVE(&pcpu->bufqueues[bp->b_qindex], bp, b_freelist); 832 bp->b_qindex = BQUEUE_NONE; 833 } else { 834 if (!BUF_LOCKINUSE(bp)) 835 panic("bremfree: removing a buffer not on a queue"); 836 } 837 } 838 839 /* 840 * bremfree() - must be called with a locked buffer 841 */ 842 void 843 bremfree(struct buf *bp) 844 { 845 struct bufpcpu *pcpu = &bufpcpu[bp->b_qcpu]; 846 847 spin_lock(&pcpu->spin); 848 _bremfree(bp); 849 spin_unlock(&pcpu->spin); 850 } 851 852 /* 853 * bremfree_locked - must be called with pcpu->spin locked 854 */ 855 static void 856 bremfree_locked(struct buf *bp) 857 { 858 _bremfree(bp); 859 } 860 861 /* 862 * This version of bread issues any required I/O asyncnronously and 863 * makes a callback on completion. 864 * 865 * The callback must check whether BIO_DONE is set in the bio and issue 866 * the bpdone(bp, 0) if it isn't. The callback is responsible for clearing 867 * BIO_DONE and disposing of the I/O (bqrelse()ing it). 868 */ 869 void 870 breadcb(struct vnode *vp, off_t loffset, int size, int bflags, 871 void (*func)(struct bio *), void *arg) 872 { 873 struct buf *bp; 874 875 bp = getblk(vp, loffset, size, 0, 0); 876 877 /* if not found in cache, do some I/O */ 878 if ((bp->b_flags & B_CACHE) == 0) { 879 bp->b_flags &= ~(B_ERROR | B_EINTR | B_INVAL | B_NOTMETA); 880 bp->b_flags |= bflags; 881 bp->b_cmd = BUF_CMD_READ; 882 bp->b_bio1.bio_done = func; 883 bp->b_bio1.bio_caller_info1.ptr = arg; 884 vfs_busy_pages(vp, bp); 885 BUF_KERNPROC(bp); 886 vn_strategy(vp, &bp->b_bio1); 887 } else if (func) { 888 /* 889 * Since we are issuing the callback synchronously it cannot 890 * race the BIO_DONE, so no need for atomic ops here. 891 */ 892 /*bp->b_bio1.bio_done = func;*/ 893 bp->b_bio1.bio_caller_info1.ptr = arg; 894 bp->b_bio1.bio_flags |= BIO_DONE; 895 func(&bp->b_bio1); 896 } else { 897 bqrelse(bp); 898 } 899 } 900 901 /* 902 * breadnx() - Terminal function for bread() and breadn(). 903 * 904 * This function will start asynchronous I/O on read-ahead blocks as well 905 * as satisfy the primary request. 906 * 907 * We must clear B_ERROR and B_INVAL prior to initiating I/O. If B_CACHE is 908 * set, the buffer is valid and we do not have to do anything. 909 */ 910 int 911 breadnx(struct vnode *vp, off_t loffset, int size, int bflags, 912 off_t *raoffset, int *rabsize, 913 int cnt, struct buf **bpp) 914 { 915 struct buf *bp, *rabp; 916 int i; 917 int rv = 0, readwait = 0; 918 int blkflags = (bflags & B_KVABIO) ? GETBLK_KVABIO : 0; 919 920 if (*bpp) 921 bp = *bpp; 922 else 923 *bpp = bp = getblk(vp, loffset, size, blkflags, 0); 924 925 /* if not found in cache, do some I/O */ 926 if ((bp->b_flags & B_CACHE) == 0) { 927 bp->b_flags &= ~(B_ERROR | B_EINTR | B_INVAL | B_NOTMETA); 928 bp->b_flags |= bflags; 929 bp->b_cmd = BUF_CMD_READ; 930 bp->b_bio1.bio_done = biodone_sync; 931 bp->b_bio1.bio_flags |= BIO_SYNC; 932 vfs_busy_pages(vp, bp); 933 vn_strategy(vp, &bp->b_bio1); 934 ++readwait; 935 } 936 937 for (i = 0; i < cnt; i++, raoffset++, rabsize++) { 938 if (inmem(vp, *raoffset)) 939 continue; 940 rabp = getblk(vp, *raoffset, *rabsize, GETBLK_KVABIO, 0); 941 942 if ((rabp->b_flags & B_CACHE) == 0) { 943 rabp->b_flags &= ~(B_ERROR | B_EINTR | 944 B_INVAL | B_NOTMETA); 945 rabp->b_flags |= (bflags & ~B_KVABIO); 946 rabp->b_cmd = BUF_CMD_READ; 947 vfs_busy_pages(vp, rabp); 948 BUF_KERNPROC(rabp); 949 vn_strategy(vp, &rabp->b_bio1); 950 } else { 951 brelse(rabp); 952 } 953 } 954 if (readwait) 955 rv = biowait(&bp->b_bio1, "biord"); 956 return (rv); 957 } 958 959 /* 960 * bwrite: 961 * 962 * Synchronous write, waits for completion. 963 * 964 * Write, release buffer on completion. (Done by iodone 965 * if async). Do not bother writing anything if the buffer 966 * is invalid. 967 * 968 * Note that we set B_CACHE here, indicating that buffer is 969 * fully valid and thus cacheable. This is true even of NFS 970 * now so we set it generally. This could be set either here 971 * or in biodone() since the I/O is synchronous. We put it 972 * here. 973 */ 974 int 975 bwrite(struct buf *bp) 976 { 977 int error; 978 979 if (bp->b_flags & B_INVAL) { 980 brelse(bp); 981 return (0); 982 } 983 if (BUF_LOCKINUSE(bp) == 0) 984 panic("bwrite: buffer is not busy???"); 985 986 /* 987 * NOTE: We no longer mark the buffer clear prior to the vn_strategy() 988 * call because it will remove the buffer from the vnode's 989 * dirty buffer list prematurely and possibly cause filesystem 990 * checks to race buffer flushes. This is now handled in 991 * bpdone(). 992 * 993 * bundirty(bp); REMOVED 994 */ 995 996 bp->b_flags &= ~(B_ERROR | B_EINTR); 997 bp->b_flags |= B_CACHE; 998 bp->b_cmd = BUF_CMD_WRITE; 999 bp->b_error = 0; 1000 bp->b_bio1.bio_done = biodone_sync; 1001 bp->b_bio1.bio_flags |= BIO_SYNC; 1002 vfs_busy_pages(bp->b_vp, bp); 1003 1004 /* 1005 * Normal bwrites pipeline writes. NOTE: b_bufsize is only 1006 * valid for vnode-backed buffers. 1007 */ 1008 bsetrunningbufspace(bp, bp->b_bufsize); 1009 vn_strategy(bp->b_vp, &bp->b_bio1); 1010 error = biowait(&bp->b_bio1, "biows"); 1011 brelse(bp); 1012 1013 return (error); 1014 } 1015 1016 /* 1017 * bawrite: 1018 * 1019 * Asynchronous write. Start output on a buffer, but do not wait for 1020 * it to complete. The buffer is released when the output completes. 1021 * 1022 * bwrite() ( or the VOP routine anyway ) is responsible for handling 1023 * B_INVAL buffers. Not us. 1024 */ 1025 void 1026 bawrite(struct buf *bp) 1027 { 1028 if (bp->b_flags & B_INVAL) { 1029 brelse(bp); 1030 return; 1031 } 1032 if (BUF_LOCKINUSE(bp) == 0) 1033 panic("bawrite: buffer is not busy???"); 1034 1035 /* 1036 * NOTE: We no longer mark the buffer clear prior to the vn_strategy() 1037 * call because it will remove the buffer from the vnode's 1038 * dirty buffer list prematurely and possibly cause filesystem 1039 * checks to race buffer flushes. This is now handled in 1040 * bpdone(). 1041 * 1042 * bundirty(bp); REMOVED 1043 */ 1044 bp->b_flags &= ~(B_ERROR | B_EINTR); 1045 bp->b_flags |= B_CACHE; 1046 bp->b_cmd = BUF_CMD_WRITE; 1047 bp->b_error = 0; 1048 KKASSERT(bp->b_bio1.bio_done == NULL); 1049 vfs_busy_pages(bp->b_vp, bp); 1050 1051 /* 1052 * Normal bwrites pipeline writes. NOTE: b_bufsize is only 1053 * valid for vnode-backed buffers. 1054 */ 1055 bsetrunningbufspace(bp, bp->b_bufsize); 1056 BUF_KERNPROC(bp); 1057 vn_strategy(bp->b_vp, &bp->b_bio1); 1058 } 1059 1060 /* 1061 * bdwrite: 1062 * 1063 * Delayed write. (Buffer is marked dirty). Do not bother writing 1064 * anything if the buffer is marked invalid. 1065 * 1066 * Note that since the buffer must be completely valid, we can safely 1067 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 1068 * biodone() in order to prevent getblk from writing the buffer 1069 * out synchronously. 1070 */ 1071 void 1072 bdwrite(struct buf *bp) 1073 { 1074 if (BUF_LOCKINUSE(bp) == 0) 1075 panic("bdwrite: buffer is not busy"); 1076 1077 if (bp->b_flags & B_INVAL) { 1078 brelse(bp); 1079 return; 1080 } 1081 bdirty(bp); 1082 1083 dsched_buf_enter(bp); /* might stack */ 1084 1085 /* 1086 * Set B_CACHE, indicating that the buffer is fully valid. This is 1087 * true even of NFS now. 1088 */ 1089 bp->b_flags |= B_CACHE; 1090 1091 /* 1092 * This bmap keeps the system from needing to do the bmap later, 1093 * perhaps when the system is attempting to do a sync. Since it 1094 * is likely that the indirect block -- or whatever other datastructure 1095 * that the filesystem needs is still in memory now, it is a good 1096 * thing to do this. Note also, that if the pageout daemon is 1097 * requesting a sync -- there might not be enough memory to do 1098 * the bmap then... So, this is important to do. 1099 */ 1100 if (bp->b_bio2.bio_offset == NOOFFSET) { 1101 VOP_BMAP(bp->b_vp, bp->b_loffset, &bp->b_bio2.bio_offset, 1102 NULL, NULL, BUF_CMD_WRITE); 1103 } 1104 1105 /* 1106 * Because the underlying pages may still be mapped and 1107 * writable trying to set the dirty buffer (b_dirtyoff/end) 1108 * range here will be inaccurate. 1109 * 1110 * However, we must still clean the pages to satisfy the 1111 * vnode_pager and pageout daemon, so they think the pages 1112 * have been "cleaned". What has really occured is that 1113 * they've been earmarked for later writing by the buffer 1114 * cache. 1115 * 1116 * So we get the b_dirtyoff/end update but will not actually 1117 * depend on it (NFS that is) until the pages are busied for 1118 * writing later on. 1119 */ 1120 vfs_clean_pages(bp); 1121 bqrelse(bp); 1122 1123 /* 1124 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 1125 * due to the softdep code. 1126 */ 1127 } 1128 1129 /* 1130 * Fake write - return pages to VM system as dirty, leave the buffer clean. 1131 * This is used by tmpfs. 1132 * 1133 * It is important for any VFS using this routine to NOT use it for 1134 * IO_SYNC or IO_ASYNC operations which occur when the system really 1135 * wants to flush VM pages to backing store. 1136 */ 1137 void 1138 buwrite(struct buf *bp) 1139 { 1140 vm_page_t m; 1141 int i; 1142 1143 /* 1144 * Only works for VMIO buffers. If the buffer is already 1145 * marked for delayed-write we can't avoid the bdwrite(). 1146 */ 1147 if ((bp->b_flags & B_VMIO) == 0 || (bp->b_flags & B_DELWRI)) { 1148 bdwrite(bp); 1149 return; 1150 } 1151 1152 /* 1153 * Mark as needing a commit. 1154 */ 1155 for (i = 0; i < bp->b_xio.xio_npages; i++) { 1156 m = bp->b_xio.xio_pages[i]; 1157 vm_page_need_commit(m); 1158 } 1159 bqrelse(bp); 1160 } 1161 1162 /* 1163 * bdirty: 1164 * 1165 * Turn buffer into delayed write request by marking it B_DELWRI. 1166 * B_RELBUF and B_NOCACHE must be cleared. 1167 * 1168 * We reassign the buffer to itself to properly update it in the 1169 * dirty/clean lists. 1170 * 1171 * Must be called from a critical section. 1172 * The buffer must be on BQUEUE_NONE. 1173 */ 1174 void 1175 bdirty(struct buf *bp) 1176 { 1177 KASSERT(bp->b_qindex == BQUEUE_NONE, 1178 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1179 if (bp->b_flags & B_NOCACHE) { 1180 kprintf("bdirty: clearing B_NOCACHE on buf %p\n", bp); 1181 bp->b_flags &= ~B_NOCACHE; 1182 } 1183 if (bp->b_flags & B_INVAL) { 1184 kprintf("bdirty: warning, dirtying invalid buffer %p\n", bp); 1185 } 1186 bp->b_flags &= ~B_RELBUF; 1187 1188 if ((bp->b_flags & B_DELWRI) == 0) { 1189 lwkt_gettoken(&bp->b_vp->v_token); 1190 bp->b_flags |= B_DELWRI; 1191 reassignbuf(bp); 1192 lwkt_reltoken(&bp->b_vp->v_token); 1193 1194 atomic_add_long(&dirtybufcount, 1); 1195 atomic_add_long(&dirtykvaspace, bp->b_kvasize); 1196 atomic_add_long(&dirtybufspace, bp->b_bufsize); 1197 if (bp->b_flags & B_HEAVY) { 1198 atomic_add_long(&dirtybufcounthw, 1); 1199 atomic_add_long(&dirtybufspacehw, bp->b_bufsize); 1200 } 1201 bd_heatup(); 1202 } 1203 } 1204 1205 /* 1206 * Set B_HEAVY, indicating that this is a heavy-weight buffer that 1207 * needs to be flushed with a different buf_daemon thread to avoid 1208 * deadlocks. B_HEAVY also imposes restrictions in getnewbuf(). 1209 */ 1210 void 1211 bheavy(struct buf *bp) 1212 { 1213 if ((bp->b_flags & B_HEAVY) == 0) { 1214 bp->b_flags |= B_HEAVY; 1215 if (bp->b_flags & B_DELWRI) { 1216 atomic_add_long(&dirtybufcounthw, 1); 1217 atomic_add_long(&dirtybufspacehw, bp->b_bufsize); 1218 } 1219 } 1220 } 1221 1222 /* 1223 * bundirty: 1224 * 1225 * Clear B_DELWRI for buffer. 1226 * 1227 * Must be called from a critical section. 1228 * 1229 * The buffer is typically on BQUEUE_NONE but there is one case in 1230 * brelse() that calls this function after placing the buffer on 1231 * a different queue. 1232 */ 1233 void 1234 bundirty(struct buf *bp) 1235 { 1236 if (bp->b_flags & B_DELWRI) { 1237 lwkt_gettoken(&bp->b_vp->v_token); 1238 bp->b_flags &= ~B_DELWRI; 1239 reassignbuf(bp); 1240 lwkt_reltoken(&bp->b_vp->v_token); 1241 1242 atomic_add_long(&dirtybufcount, -1); 1243 atomic_add_long(&dirtykvaspace, -bp->b_kvasize); 1244 atomic_add_long(&dirtybufspace, -bp->b_bufsize); 1245 if (bp->b_flags & B_HEAVY) { 1246 atomic_add_long(&dirtybufcounthw, -1); 1247 atomic_add_long(&dirtybufspacehw, -bp->b_bufsize); 1248 } 1249 bd_signal(bp->b_bufsize); 1250 } 1251 /* 1252 * Since it is now being written, we can clear its deferred write flag. 1253 */ 1254 bp->b_flags &= ~B_DEFERRED; 1255 } 1256 1257 /* 1258 * Set the b_runningbufspace field, used to track how much I/O is 1259 * in progress at any given moment. 1260 */ 1261 void 1262 bsetrunningbufspace(struct buf *bp, int bytes) 1263 { 1264 bp->b_runningbufspace = bytes; 1265 if (bytes) { 1266 atomic_add_long(&runningbufspace, bytes); 1267 atomic_add_long(&runningbufcount, 1); 1268 } 1269 } 1270 1271 /* 1272 * brelse: 1273 * 1274 * Release a busy buffer and, if requested, free its resources. The 1275 * buffer will be stashed in the appropriate bufqueue[] allowing it 1276 * to be accessed later as a cache entity or reused for other purposes. 1277 */ 1278 void 1279 brelse(struct buf *bp) 1280 { 1281 struct bufpcpu *pcpu; 1282 #ifdef INVARIANTS 1283 int saved_flags = bp->b_flags; 1284 #endif 1285 1286 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1287 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1288 1289 /* 1290 * If B_NOCACHE is set we are being asked to destroy the buffer and 1291 * its backing store. Clear B_DELWRI. 1292 * 1293 * B_NOCACHE is set in two cases: (1) when the caller really wants 1294 * to destroy the buffer and backing store and (2) when the caller 1295 * wants to destroy the buffer and backing store after a write 1296 * completes. 1297 */ 1298 if ((bp->b_flags & (B_NOCACHE|B_DELWRI)) == (B_NOCACHE|B_DELWRI)) { 1299 bundirty(bp); 1300 } 1301 1302 if ((bp->b_flags & (B_INVAL | B_DELWRI)) == B_DELWRI) { 1303 /* 1304 * A re-dirtied buffer is only subject to destruction 1305 * by B_INVAL. B_ERROR and B_NOCACHE are ignored. 1306 */ 1307 /* leave buffer intact */ 1308 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR)) || 1309 (bp->b_bufsize <= 0)) { 1310 /* 1311 * Either a failed read or we were asked to free or not 1312 * cache the buffer. This path is reached with B_DELWRI 1313 * set only if B_INVAL is already set. B_NOCACHE governs 1314 * backing store destruction. 1315 * 1316 * NOTE: HAMMER will set B_LOCKED in buf_deallocate if the 1317 * buffer cannot be immediately freed. 1318 */ 1319 bp->b_flags |= B_INVAL; 1320 if (LIST_FIRST(&bp->b_dep) != NULL) 1321 buf_deallocate(bp); 1322 if (bp->b_flags & B_DELWRI) { 1323 atomic_add_long(&dirtybufcount, -1); 1324 atomic_add_long(&dirtykvaspace, -bp->b_kvasize); 1325 atomic_add_long(&dirtybufspace, -bp->b_bufsize); 1326 if (bp->b_flags & B_HEAVY) { 1327 atomic_add_long(&dirtybufcounthw, -1); 1328 atomic_add_long(&dirtybufspacehw, 1329 -bp->b_bufsize); 1330 } 1331 bd_signal(bp->b_bufsize); 1332 } 1333 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1334 } 1335 1336 /* 1337 * We must clear B_RELBUF if B_DELWRI or B_LOCKED is set, 1338 * or if b_refs is non-zero. 1339 * 1340 * If vfs_vmio_release() is called with either bit set, the 1341 * underlying pages may wind up getting freed causing a previous 1342 * write (bdwrite()) to get 'lost' because pages associated with 1343 * a B_DELWRI bp are marked clean. Pages associated with a 1344 * B_LOCKED buffer may be mapped by the filesystem. 1345 * 1346 * If we want to release the buffer ourselves (rather then the 1347 * originator asking us to release it), give the originator a 1348 * chance to countermand the release by setting B_LOCKED. 1349 * 1350 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1351 * if B_DELWRI is set. 1352 * 1353 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1354 * on pages to return pages to the VM page queues. 1355 */ 1356 if ((bp->b_flags & (B_DELWRI | B_LOCKED)) || bp->b_refs) { 1357 bp->b_flags &= ~B_RELBUF; 1358 } else if (vm_page_count_min(0)) { 1359 if (LIST_FIRST(&bp->b_dep) != NULL) 1360 buf_deallocate(bp); /* can set B_LOCKED */ 1361 if (bp->b_flags & (B_DELWRI | B_LOCKED)) 1362 bp->b_flags &= ~B_RELBUF; 1363 else 1364 bp->b_flags |= B_RELBUF; 1365 } 1366 1367 /* 1368 * Make sure b_cmd is clear. It may have already been cleared by 1369 * biodone(). 1370 * 1371 * At this point destroying the buffer is governed by the B_INVAL 1372 * or B_RELBUF flags. 1373 */ 1374 bp->b_cmd = BUF_CMD_DONE; 1375 dsched_buf_exit(bp); 1376 1377 /* 1378 * VMIO buffer rundown. Make sure the VM page array is restored 1379 * after an I/O may have replaces some of the pages with bogus pages 1380 * in order to not destroy dirty pages in a fill-in read. 1381 * 1382 * Note that due to the code above, if a buffer is marked B_DELWRI 1383 * then the B_RELBUF and B_NOCACHE bits will always be clear. 1384 * B_INVAL may still be set, however. 1385 * 1386 * For clean buffers, B_INVAL or B_RELBUF will destroy the buffer 1387 * but not the backing store. B_NOCACHE will destroy the backing 1388 * store. 1389 * 1390 * Note that dirty NFS buffers contain byte-granular write ranges 1391 * and should not be destroyed w/ B_INVAL even if the backing store 1392 * is left intact. 1393 */ 1394 if (bp->b_flags & B_VMIO) { 1395 /* 1396 * Rundown for VMIO buffers which are not dirty NFS buffers. 1397 */ 1398 int i, j, resid; 1399 vm_page_t m; 1400 off_t foff; 1401 vm_pindex_t poff; 1402 vm_object_t obj; 1403 struct vnode *vp; 1404 1405 vp = bp->b_vp; 1406 1407 /* 1408 * Get the base offset and length of the buffer. Note that 1409 * in the VMIO case if the buffer block size is not 1410 * page-aligned then b_data pointer may not be page-aligned. 1411 * But our b_xio.xio_pages array *IS* page aligned. 1412 * 1413 * block sizes less then DEV_BSIZE (usually 512) are not 1414 * supported due to the page granularity bits (m->valid, 1415 * m->dirty, etc...). 1416 * 1417 * See man buf(9) for more information 1418 */ 1419 1420 resid = bp->b_bufsize; 1421 foff = bp->b_loffset; 1422 1423 for (i = 0; i < bp->b_xio.xio_npages; i++) { 1424 m = bp->b_xio.xio_pages[i]; 1425 1426 /* 1427 * If we hit a bogus page, fixup *all* of them 1428 * now. Note that we left these pages wired 1429 * when we removed them so they had better exist, 1430 * and they cannot be ripped out from under us so 1431 * no critical section protection is necessary. 1432 */ 1433 if (m == bogus_page) { 1434 obj = vp->v_object; 1435 poff = OFF_TO_IDX(bp->b_loffset); 1436 1437 vm_object_hold(obj); 1438 for (j = i; j < bp->b_xio.xio_npages; j++) { 1439 vm_page_t mtmp; 1440 1441 mtmp = bp->b_xio.xio_pages[j]; 1442 if (mtmp == bogus_page) { 1443 if ((bp->b_flags & B_HASBOGUS) == 0) 1444 panic("brelse: bp %p corrupt bogus", bp); 1445 mtmp = vm_page_lookup(obj, poff + j); 1446 if (!mtmp) 1447 panic("brelse: bp %p page %d missing", bp, j); 1448 bp->b_xio.xio_pages[j] = mtmp; 1449 } 1450 } 1451 vm_object_drop(obj); 1452 1453 if ((bp->b_flags & B_HASBOGUS) || 1454 (bp->b_flags & B_INVAL) == 0) { 1455 pmap_qenter_noinval( 1456 trunc_page((vm_offset_t)bp->b_data), 1457 bp->b_xio.xio_pages, 1458 bp->b_xio.xio_npages); 1459 bp->b_flags &= ~B_HASBOGUS; 1460 bp->b_flags |= B_KVABIO; 1461 bkvareset(bp); 1462 } 1463 m = bp->b_xio.xio_pages[i]; 1464 } 1465 1466 /* 1467 * Invalidate the backing store if B_NOCACHE is set 1468 * (e.g. used with vinvalbuf()). If this is NFS 1469 * we impose a requirement that the block size be 1470 * a multiple of PAGE_SIZE and create a temporary 1471 * hack to basically invalidate the whole page. The 1472 * problem is that NFS uses really odd buffer sizes 1473 * especially when tracking piecemeal writes and 1474 * it also vinvalbuf()'s a lot, which would result 1475 * in only partial page validation and invalidation 1476 * here. If the file page is mmap()'d, however, 1477 * all the valid bits get set so after we invalidate 1478 * here we would end up with weird m->valid values 1479 * like 0xfc. nfs_getpages() can't handle this so 1480 * we clear all the valid bits for the NFS case 1481 * instead of just some of them. 1482 * 1483 * The real bug is the VM system having to set m->valid 1484 * to VM_PAGE_BITS_ALL for faulted-in pages, which 1485 * itself is an artifact of the whole 512-byte 1486 * granular mess that exists to support odd block 1487 * sizes and UFS meta-data block sizes (e.g. 6144). 1488 * A complete rewrite is required. 1489 * 1490 * XXX 1491 */ 1492 if (bp->b_flags & (B_NOCACHE|B_ERROR)) { 1493 int poffset = foff & PAGE_MASK; 1494 int presid; 1495 1496 presid = PAGE_SIZE - poffset; 1497 if (bp->b_vp->v_tag == VT_NFS && 1498 bp->b_vp->v_type == VREG) { 1499 ; /* entire page */ 1500 } else if (presid > resid) { 1501 presid = resid; 1502 } 1503 KASSERT(presid >= 0, ("brelse: extra page")); 1504 vm_page_set_invalid(m, poffset, presid); 1505 1506 /* 1507 * Also make sure any swap cache is removed 1508 * as it is now stale (HAMMER in particular 1509 * uses B_NOCACHE to deal with buffer 1510 * aliasing). 1511 */ 1512 swap_pager_unswapped(m); 1513 } 1514 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1515 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1516 } 1517 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1518 vfs_vmio_release(bp); 1519 } else { 1520 /* 1521 * Rundown for non-VMIO buffers. 1522 * 1523 * XXX With B_MALLOC buffers removed, there should no longer 1524 * be any situation where brelse() is called on a non B_VMIO 1525 * buffer. Recommend assertion here. XXX 1526 */ 1527 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1528 if (bp->b_bufsize) 1529 allocbuf(bp, 0); 1530 KKASSERT (LIST_FIRST(&bp->b_dep) == NULL); 1531 if (bp->b_vp) 1532 brelvp(bp); 1533 } 1534 } 1535 1536 if (bp->b_qindex != BQUEUE_NONE) 1537 panic("brelse: free buffer onto another queue???"); 1538 1539 /* 1540 * Figure out the correct queue to place the cleaned up buffer on. 1541 * Buffers placed in the EMPTY or EMPTYKVA had better already be 1542 * disassociated from their vnode. 1543 * 1544 * Return the buffer to its original pcpu area 1545 */ 1546 pcpu = &bufpcpu[bp->b_qcpu]; 1547 spin_lock(&pcpu->spin); 1548 1549 if (bp->b_flags & B_LOCKED) { 1550 /* 1551 * Buffers that are locked are placed in the locked queue 1552 * immediately, regardless of their state. 1553 */ 1554 bp->b_qindex = BQUEUE_LOCKED; 1555 TAILQ_INSERT_TAIL(&pcpu->bufqueues[bp->b_qindex], 1556 bp, b_freelist); 1557 } else if (bp->b_bufsize == 0) { 1558 /* 1559 * Buffers with no memory. Due to conditionals near the top 1560 * of brelse() such buffers should probably already be 1561 * marked B_INVAL and disassociated from their vnode. 1562 */ 1563 bp->b_flags |= B_INVAL; 1564 KASSERT(bp->b_vp == NULL, 1565 ("bp1 %p flags %08x/%08x vnode %p " 1566 "unexpectededly still associated!", 1567 bp, saved_flags, bp->b_flags, bp->b_vp)); 1568 KKASSERT((bp->b_flags & B_HASHED) == 0); 1569 bp->b_qindex = BQUEUE_EMPTY; 1570 TAILQ_INSERT_HEAD(&pcpu->bufqueues[bp->b_qindex], 1571 bp, b_freelist); 1572 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) { 1573 /* 1574 * Buffers with junk contents. Again these buffers had better 1575 * already be disassociated from their vnode. 1576 */ 1577 KASSERT(bp->b_vp == NULL, 1578 ("bp2 %p flags %08x/%08x vnode %p unexpectededly " 1579 "still associated!", 1580 bp, saved_flags, bp->b_flags, bp->b_vp)); 1581 KKASSERT((bp->b_flags & B_HASHED) == 0); 1582 bp->b_flags |= B_INVAL; 1583 bp->b_qindex = BQUEUE_CLEAN; 1584 TAILQ_INSERT_HEAD(&pcpu->bufqueues[bp->b_qindex], 1585 bp, b_freelist); 1586 } else { 1587 /* 1588 * Remaining buffers. These buffers are still associated with 1589 * their vnode. 1590 */ 1591 switch(bp->b_flags & (B_DELWRI|B_HEAVY)) { 1592 case B_DELWRI: 1593 bp->b_qindex = BQUEUE_DIRTY; 1594 TAILQ_INSERT_TAIL(&pcpu->bufqueues[bp->b_qindex], 1595 bp, b_freelist); 1596 break; 1597 case B_DELWRI | B_HEAVY: 1598 bp->b_qindex = BQUEUE_DIRTY_HW; 1599 TAILQ_INSERT_TAIL(&pcpu->bufqueues[bp->b_qindex], 1600 bp, b_freelist); 1601 break; 1602 default: 1603 /* 1604 * NOTE: Buffers are always placed at the end of the 1605 * queue. If B_AGE is not set the buffer will cycle 1606 * through the queue twice. 1607 */ 1608 bp->b_qindex = BQUEUE_CLEAN; 1609 TAILQ_INSERT_TAIL(&pcpu->bufqueues[bp->b_qindex], 1610 bp, b_freelist); 1611 break; 1612 } 1613 } 1614 spin_unlock(&pcpu->spin); 1615 1616 /* 1617 * If B_INVAL, clear B_DELWRI. We've already placed the buffer 1618 * on the correct queue but we have not yet unlocked it. 1619 */ 1620 if ((bp->b_flags & (B_INVAL|B_DELWRI)) == (B_INVAL|B_DELWRI)) 1621 bundirty(bp); 1622 1623 /* 1624 * The bp is on an appropriate queue unless locked. If it is not 1625 * locked or dirty we can wakeup threads waiting for buffer space. 1626 * 1627 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1628 * if B_INVAL is set ). 1629 */ 1630 if ((bp->b_flags & (B_LOCKED|B_DELWRI)) == 0) 1631 bufcountwakeup(); 1632 1633 /* 1634 * Something we can maybe free or reuse 1635 */ 1636 if (bp->b_bufsize || bp->b_kvasize) 1637 bufspacewakeup(); 1638 1639 /* 1640 * Clean up temporary flags and unlock the buffer. 1641 */ 1642 bp->b_flags &= ~(B_NOCACHE | B_RELBUF | B_DIRECT); 1643 BUF_UNLOCK(bp); 1644 } 1645 1646 /* 1647 * bqrelse: 1648 * 1649 * Release a buffer back to the appropriate queue but do not try to free 1650 * it. The buffer is expected to be used again soon. 1651 * 1652 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1653 * biodone() to requeue an async I/O on completion. It is also used when 1654 * known good buffers need to be requeued but we think we may need the data 1655 * again soon. 1656 * 1657 * XXX we should be able to leave the B_RELBUF hint set on completion. 1658 */ 1659 void 1660 bqrelse(struct buf *bp) 1661 { 1662 struct bufpcpu *pcpu; 1663 1664 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1665 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1666 1667 if (bp->b_qindex != BQUEUE_NONE) 1668 panic("bqrelse: free buffer onto another queue???"); 1669 1670 buf_act_advance(bp); 1671 1672 pcpu = &bufpcpu[bp->b_qcpu]; 1673 spin_lock(&pcpu->spin); 1674 1675 if (bp->b_flags & B_LOCKED) { 1676 /* 1677 * Locked buffers are released to the locked queue. However, 1678 * if the buffer is dirty it will first go into the dirty 1679 * queue and later on after the I/O completes successfully it 1680 * will be released to the locked queue. 1681 */ 1682 bp->b_qindex = BQUEUE_LOCKED; 1683 TAILQ_INSERT_TAIL(&pcpu->bufqueues[bp->b_qindex], 1684 bp, b_freelist); 1685 } else if (bp->b_flags & B_DELWRI) { 1686 bp->b_qindex = (bp->b_flags & B_HEAVY) ? 1687 BQUEUE_DIRTY_HW : BQUEUE_DIRTY; 1688 TAILQ_INSERT_TAIL(&pcpu->bufqueues[bp->b_qindex], 1689 bp, b_freelist); 1690 } else if (vm_page_count_min(0)) { 1691 /* 1692 * We are too low on memory, we have to try to free the 1693 * buffer (most importantly: the wired pages making up its 1694 * backing store) *now*. 1695 */ 1696 spin_unlock(&pcpu->spin); 1697 brelse(bp); 1698 return; 1699 } else { 1700 bp->b_qindex = BQUEUE_CLEAN; 1701 TAILQ_INSERT_TAIL(&pcpu->bufqueues[bp->b_qindex], 1702 bp, b_freelist); 1703 } 1704 spin_unlock(&pcpu->spin); 1705 1706 /* 1707 * We have now placed the buffer on the proper queue, but have yet 1708 * to unlock it. 1709 */ 1710 if ((bp->b_flags & B_LOCKED) == 0 && 1711 ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0)) { 1712 bufcountwakeup(); 1713 } 1714 1715 /* 1716 * Something we can maybe free or reuse. 1717 */ 1718 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1719 bufspacewakeup(); 1720 1721 /* 1722 * Final cleanup and unlock. Clear bits that are only used while a 1723 * buffer is actively locked. 1724 */ 1725 bp->b_flags &= ~(B_NOCACHE | B_RELBUF); 1726 dsched_buf_exit(bp); 1727 BUF_UNLOCK(bp); 1728 } 1729 1730 /* 1731 * Hold a buffer, preventing it from being reused. This will prevent 1732 * normal B_RELBUF operations on the buffer but will not prevent B_INVAL 1733 * operations. If a B_INVAL operation occurs the buffer will remain held 1734 * but the underlying pages may get ripped out. 1735 * 1736 * These functions are typically used in VOP_READ/VOP_WRITE functions 1737 * to hold a buffer during a copyin or copyout, preventing deadlocks 1738 * or recursive lock panics when read()/write() is used over mmap()'d 1739 * space. 1740 * 1741 * NOTE: bqhold() requires that the buffer be locked at the time of the 1742 * hold. bqdrop() has no requirements other than the buffer having 1743 * previously been held. 1744 */ 1745 void 1746 bqhold(struct buf *bp) 1747 { 1748 atomic_add_int(&bp->b_refs, 1); 1749 } 1750 1751 void 1752 bqdrop(struct buf *bp) 1753 { 1754 KKASSERT(bp->b_refs > 0); 1755 atomic_add_int(&bp->b_refs, -1); 1756 } 1757 1758 /* 1759 * Return backing pages held by the buffer 'bp' back to the VM system. 1760 * This routine is called when the bp is invalidated, released, or 1761 * reused. 1762 * 1763 * The KVA mapping (b_data) for the underlying pages is removed by 1764 * this function. 1765 * 1766 * WARNING! This routine is integral to the low memory critical path 1767 * when a buffer is B_RELBUF'd. If the system has a severe page 1768 * deficit we need to get the page(s) onto the PQ_FREE or PQ_CACHE 1769 * queues so they can be reused in the current pageout daemon 1770 * pass. 1771 */ 1772 static void 1773 vfs_vmio_release(struct buf *bp) 1774 { 1775 int i; 1776 vm_page_t m; 1777 1778 for (i = 0; i < bp->b_xio.xio_npages; i++) { 1779 m = bp->b_xio.xio_pages[i]; 1780 bp->b_xio.xio_pages[i] = NULL; 1781 1782 /* 1783 * We need to own the page in order to safely unwire it. 1784 */ 1785 vm_page_busy_wait(m, FALSE, "vmiopg"); 1786 1787 /* 1788 * The VFS is telling us this is not a meta-data buffer 1789 * even if it is backed by a block device. 1790 */ 1791 if (bp->b_flags & B_NOTMETA) 1792 vm_page_flag_set(m, PG_NOTMETA); 1793 1794 /* 1795 * This is a very important bit of code. We try to track 1796 * VM page use whether the pages are wired into the buffer 1797 * cache or not. While wired into the buffer cache the 1798 * bp tracks the act_count. 1799 * 1800 * We can choose to place unwired pages on the inactive 1801 * queue (0) or active queue (1). If we place too many 1802 * on the active queue the queue will cycle the act_count 1803 * on pages we'd like to keep, just from single-use pages 1804 * (such as when doing a tar-up or file scan). 1805 */ 1806 if (bp->b_act_count < vm_cycle_point) 1807 vm_page_unwire(m, 0); 1808 else 1809 vm_page_unwire(m, 1); 1810 1811 /* 1812 * If the wire_count has dropped to 0 we may need to take 1813 * further action before unbusying the page. 1814 * 1815 * WARNING: vm_page_try_*() also checks PG_NEED_COMMIT for us. 1816 */ 1817 if (m->wire_count == 0) { 1818 if (bp->b_flags & B_DIRECT) { 1819 /* 1820 * Attempt to free the page if B_DIRECT is 1821 * set, the caller does not desire the page 1822 * to be cached. 1823 */ 1824 vm_page_wakeup(m); 1825 vm_page_try_to_free(m); 1826 } else if ((bp->b_flags & B_NOTMETA) || 1827 vm_page_count_min(0)) { 1828 /* 1829 * Attempt to move the page to PQ_CACHE 1830 * if B_NOTMETA is set. This flag is set 1831 * by HAMMER to remove one of the two pages 1832 * present when double buffering is enabled. 1833 * 1834 * Attempt to move the page to PQ_CACHE 1835 * If we have a severe page deficit. This 1836 * will cause buffer cache operations related 1837 * to pageouts to recycle the related pages 1838 * in order to avoid a low memory deadlock. 1839 */ 1840 m->act_count = bp->b_act_count; 1841 vm_page_try_to_cache(m); 1842 } else { 1843 /* 1844 * Nominal case, leave the page on the 1845 * queue the original unwiring placed it on 1846 * (active or inactive). 1847 */ 1848 m->act_count = bp->b_act_count; 1849 vm_page_wakeup(m); 1850 } 1851 } else { 1852 vm_page_wakeup(m); 1853 } 1854 } 1855 1856 /* 1857 * Zero out the pmap pte's for the mapping, but don't bother 1858 * invalidating the TLB. The range will be properly invalidating 1859 * when new pages are entered into the mapping. 1860 * 1861 * This in particular reduces tmpfs tear-down overhead and reduces 1862 * buffer cache re-use overhead (one invalidation sequence instead 1863 * of two per re-use). 1864 */ 1865 pmap_qremove_noinval(trunc_page((vm_offset_t) bp->b_data), 1866 bp->b_xio.xio_npages); 1867 CPUMASK_ASSZERO(bp->b_cpumask); 1868 if (bp->b_bufsize) { 1869 atomic_add_long(&bufspace, -bp->b_bufsize); 1870 bp->b_bufsize = 0; 1871 bufspacewakeup(); 1872 } 1873 bp->b_xio.xio_npages = 0; 1874 bp->b_flags &= ~B_VMIO; 1875 KKASSERT (LIST_FIRST(&bp->b_dep) == NULL); 1876 if (bp->b_vp) 1877 brelvp(bp); 1878 } 1879 1880 /* 1881 * Find and initialize a new buffer header, freeing up existing buffers 1882 * in the bufqueues as necessary. The new buffer is returned locked. 1883 * 1884 * Important: B_INVAL is not set. If the caller wishes to throw the 1885 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1886 * 1887 * We block if: 1888 * We have insufficient buffer headers 1889 * We have insufficient buffer space 1890 * 1891 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1892 * Instead we ask the buf daemon to do it for us. We attempt to 1893 * avoid piecemeal wakeups of the pageout daemon. 1894 */ 1895 struct buf * 1896 getnewbuf(int blkflags, int slptimeo, int size, int maxsize) 1897 { 1898 struct bufpcpu *pcpu; 1899 struct buf *bp; 1900 struct buf *nbp; 1901 int nqindex; 1902 int nqcpu; 1903 int slpflags = (blkflags & GETBLK_PCATCH) ? PCATCH : 0; 1904 int maxloops = 200000; 1905 int restart_reason = 0; 1906 struct buf *restart_bp = NULL; 1907 static char flushingbufs[MAXCPU]; 1908 char *flushingp; 1909 1910 /* 1911 * We can't afford to block since we might be holding a vnode lock, 1912 * which may prevent system daemons from running. We deal with 1913 * low-memory situations by proactively returning memory and running 1914 * async I/O rather then sync I/O. 1915 */ 1916 1917 ++getnewbufcalls; 1918 nqcpu = mycpu->gd_cpuid; 1919 flushingp = &flushingbufs[nqcpu]; 1920 restart: 1921 if (bufspace < lobufspace) 1922 *flushingp = 0; 1923 1924 if (debug_bufbio && --maxloops == 0) 1925 panic("getnewbuf, excessive loops on cpu %d restart %d (%p)", 1926 mycpu->gd_cpuid, restart_reason, restart_bp); 1927 1928 /* 1929 * Setup for scan. If we do not have enough free buffers, 1930 * we setup a degenerate case that immediately fails. Note 1931 * that if we are specially marked process, we are allowed to 1932 * dip into our reserves. 1933 * 1934 * The scanning sequence is nominally: EMPTY->CLEAN 1935 */ 1936 pcpu = &bufpcpu[nqcpu]; 1937 spin_lock(&pcpu->spin); 1938 1939 /* 1940 * Prime the scan for this cpu. Locate the first buffer to 1941 * check. If we are flushing buffers we must skip the 1942 * EMPTY queue. 1943 */ 1944 nqindex = BQUEUE_EMPTY; 1945 nbp = TAILQ_FIRST(&pcpu->bufqueues[BQUEUE_EMPTY]); 1946 if (nbp == NULL || *flushingp) { 1947 nqindex = BQUEUE_CLEAN; 1948 nbp = TAILQ_FIRST(&pcpu->bufqueues[BQUEUE_CLEAN]); 1949 } 1950 1951 /* 1952 * Run scan, possibly freeing data and/or kva mappings on the fly, 1953 * depending. 1954 * 1955 * WARNING! spin is held! 1956 */ 1957 while ((bp = nbp) != NULL) { 1958 int qindex = nqindex; 1959 1960 nbp = TAILQ_NEXT(bp, b_freelist); 1961 1962 /* 1963 * BQUEUE_CLEAN - B_AGE special case. If not set the bp 1964 * cycles through the queue twice before being selected. 1965 */ 1966 if (qindex == BQUEUE_CLEAN && 1967 (bp->b_flags & B_AGE) == 0 && nbp) { 1968 bp->b_flags |= B_AGE; 1969 TAILQ_REMOVE(&pcpu->bufqueues[qindex], 1970 bp, b_freelist); 1971 TAILQ_INSERT_TAIL(&pcpu->bufqueues[qindex], 1972 bp, b_freelist); 1973 continue; 1974 } 1975 1976 /* 1977 * Calculate next bp ( we can only use it if we do not block 1978 * or do other fancy things ). 1979 */ 1980 if (nbp == NULL) { 1981 switch(qindex) { 1982 case BQUEUE_EMPTY: 1983 nqindex = BQUEUE_CLEAN; 1984 if ((nbp = TAILQ_FIRST(&pcpu->bufqueues[BQUEUE_CLEAN]))) 1985 break; 1986 /* fall through */ 1987 case BQUEUE_CLEAN: 1988 /* 1989 * nbp is NULL. 1990 */ 1991 break; 1992 } 1993 } 1994 1995 /* 1996 * Sanity Checks 1997 */ 1998 KASSERT(bp->b_qindex == qindex, 1999 ("getnewbuf: inconsistent queue %d bp %p", qindex, bp)); 2000 2001 /* 2002 * Note: we no longer distinguish between VMIO and non-VMIO 2003 * buffers. 2004 */ 2005 KASSERT((bp->b_flags & B_DELWRI) == 0, 2006 ("delwri buffer %p found in queue %d", bp, qindex)); 2007 2008 /* 2009 * Do not try to reuse a buffer with a non-zero b_refs. 2010 * This is an unsynchronized test. A synchronized test 2011 * is also performed after we lock the buffer. 2012 */ 2013 if (bp->b_refs) 2014 continue; 2015 2016 /* 2017 * Start freeing the bp. This is somewhat involved. nbp 2018 * remains valid only for BQUEUE_EMPTY bp's. Buffers 2019 * on the clean list must be disassociated from their 2020 * current vnode. Buffers on the empty lists have 2021 * already been disassociated. 2022 * 2023 * b_refs is checked after locking along with queue changes. 2024 * We must check here to deal with zero->nonzero transitions 2025 * made by the owner of the buffer lock, which is used by 2026 * VFS's to hold the buffer while issuing an unlocked 2027 * uiomove()s. We cannot invalidate the buffer's pages 2028 * for this case. Once we successfully lock a buffer the 2029 * only 0->1 transitions of b_refs will occur via findblk(). 2030 * 2031 * We must also check for queue changes after successful 2032 * locking as the current lock holder may dispose of the 2033 * buffer and change its queue. 2034 */ 2035 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) { 2036 spin_unlock(&pcpu->spin); 2037 tsleep(&bd_request, 0, "gnbxxx", (hz + 99) / 100); 2038 restart_reason = 1; 2039 restart_bp = bp; 2040 goto restart; 2041 } 2042 if (bp->b_qindex != qindex || bp->b_refs) { 2043 spin_unlock(&pcpu->spin); 2044 BUF_UNLOCK(bp); 2045 restart_reason = 2; 2046 restart_bp = bp; 2047 goto restart; 2048 } 2049 bremfree_locked(bp); 2050 spin_unlock(&pcpu->spin); 2051 2052 /* 2053 * Dependancies must be handled before we disassociate the 2054 * vnode. 2055 * 2056 * NOTE: HAMMER will set B_LOCKED if the buffer cannot 2057 * be immediately disassociated. HAMMER then becomes 2058 * responsible for releasing the buffer. 2059 * 2060 * NOTE: spin is UNLOCKED now. 2061 */ 2062 if (LIST_FIRST(&bp->b_dep) != NULL) { 2063 buf_deallocate(bp); 2064 if (bp->b_flags & B_LOCKED) { 2065 bqrelse(bp); 2066 restart_reason = 3; 2067 restart_bp = bp; 2068 goto restart; 2069 } 2070 KKASSERT(LIST_FIRST(&bp->b_dep) == NULL); 2071 } 2072 2073 /* 2074 * CLEAN buffers have content or associations that must be 2075 * cleaned out if not repurposing. 2076 */ 2077 if (qindex == BQUEUE_CLEAN) { 2078 if (bp->b_flags & B_VMIO) 2079 vfs_vmio_release(bp); 2080 if (bp->b_vp) 2081 brelvp(bp); 2082 } 2083 2084 /* 2085 * NOTE: nbp is now entirely invalid. We can only restart 2086 * the scan from this point on. 2087 * 2088 * Get the rest of the buffer freed up. b_kva* is still 2089 * valid after this operation. 2090 */ 2091 KASSERT(bp->b_vp == NULL, 2092 ("bp3 %p flags %08x vnode %p qindex %d " 2093 "unexpectededly still associated!", 2094 bp, bp->b_flags, bp->b_vp, qindex)); 2095 KKASSERT((bp->b_flags & B_HASHED) == 0); 2096 2097 if (bp->b_bufsize) 2098 allocbuf(bp, 0); 2099 2100 if (bp->b_flags & (B_VNDIRTY | B_VNCLEAN | B_HASHED)) { 2101 kprintf("getnewbuf: caught bug vp queue " 2102 "%p/%08x qidx %d\n", 2103 bp, bp->b_flags, qindex); 2104 brelvp(bp); 2105 } 2106 bp->b_flags = B_BNOCLIP; 2107 bp->b_cmd = BUF_CMD_DONE; 2108 bp->b_vp = NULL; 2109 bp->b_error = 0; 2110 bp->b_resid = 0; 2111 bp->b_bcount = 0; 2112 bp->b_xio.xio_npages = 0; 2113 bp->b_dirtyoff = bp->b_dirtyend = 0; 2114 bp->b_act_count = ACT_INIT; 2115 reinitbufbio(bp); 2116 KKASSERT(LIST_FIRST(&bp->b_dep) == NULL); 2117 buf_dep_init(bp); 2118 if (blkflags & GETBLK_BHEAVY) 2119 bp->b_flags |= B_HEAVY; 2120 2121 if (bufspace >= hibufspace) 2122 *flushingp = 1; 2123 if (bufspace < lobufspace) 2124 *flushingp = 0; 2125 if (*flushingp) { 2126 bp->b_flags |= B_INVAL; 2127 brelse(bp); 2128 restart_reason = 5; 2129 restart_bp = bp; 2130 goto restart; 2131 } 2132 2133 /* 2134 * b_refs can transition to a non-zero value while we hold 2135 * the buffer locked due to a findblk(). Our brelvp() above 2136 * interlocked any future possible transitions due to 2137 * findblk()s. 2138 * 2139 * If we find b_refs to be non-zero we can destroy the 2140 * buffer's contents but we cannot yet reuse the buffer. 2141 */ 2142 if (bp->b_refs) { 2143 bp->b_flags |= B_INVAL; 2144 brelse(bp); 2145 restart_reason = 6; 2146 restart_bp = bp; 2147 2148 goto restart; 2149 } 2150 2151 /* 2152 * We found our buffer! 2153 */ 2154 break; 2155 } 2156 2157 /* 2158 * If we exhausted our list, iterate other cpus. If that fails, 2159 * sleep as appropriate. We may have to wakeup various daemons 2160 * and write out some dirty buffers. 2161 * 2162 * Generally we are sleeping due to insufficient buffer space. 2163 * 2164 * NOTE: spin is held if bp is NULL, else it is not held. 2165 */ 2166 if (bp == NULL) { 2167 int flags; 2168 char *waitmsg; 2169 2170 spin_unlock(&pcpu->spin); 2171 2172 nqcpu = (nqcpu + 1) % ncpus; 2173 if (nqcpu != mycpu->gd_cpuid) { 2174 restart_reason = 7; 2175 restart_bp = bp; 2176 goto restart; 2177 } 2178 2179 if (bufspace >= hibufspace) { 2180 waitmsg = "bufspc"; 2181 flags = VFS_BIO_NEED_BUFSPACE; 2182 } else { 2183 waitmsg = "newbuf"; 2184 flags = VFS_BIO_NEED_ANY; 2185 } 2186 2187 bd_speedup(); /* heeeelp */ 2188 atomic_set_int(&needsbuffer, flags); 2189 while (needsbuffer & flags) { 2190 int value; 2191 2192 tsleep_interlock(&needsbuffer, 0); 2193 value = atomic_fetchadd_int(&needsbuffer, 0); 2194 if (value & flags) { 2195 if (tsleep(&needsbuffer, PINTERLOCKED|slpflags, 2196 waitmsg, slptimeo)) { 2197 return (NULL); 2198 } 2199 } 2200 } 2201 } else { 2202 /* 2203 * We finally have a valid bp. Reset b_data. 2204 * 2205 * (spin is not held) 2206 */ 2207 bp->b_data = bp->b_kvabase; 2208 } 2209 return(bp); 2210 } 2211 2212 /* 2213 * buf_daemon: 2214 * 2215 * Buffer flushing daemon. Buffers are normally flushed by the 2216 * update daemon but if it cannot keep up this process starts to 2217 * take the load in an attempt to prevent getnewbuf() from blocking. 2218 * 2219 * Once a flush is initiated it does not stop until the number 2220 * of buffers falls below lodirtybuffers, but we will wake up anyone 2221 * waiting at the mid-point. 2222 */ 2223 static struct kproc_desc buf_kp = { 2224 "bufdaemon", 2225 buf_daemon, 2226 &bufdaemon_td 2227 }; 2228 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, 2229 kproc_start, &buf_kp); 2230 2231 static struct kproc_desc bufhw_kp = { 2232 "bufdaemon_hw", 2233 buf_daemon_hw, 2234 &bufdaemonhw_td 2235 }; 2236 SYSINIT(bufdaemon_hw, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, 2237 kproc_start, &bufhw_kp); 2238 2239 static void 2240 buf_daemon1(struct thread *td, int queue, int (*buf_limit_fn)(long), 2241 int *bd_req) 2242 { 2243 long limit; 2244 struct buf *marker; 2245 2246 marker = kmalloc(sizeof(*marker), M_BIOBUF, M_WAITOK | M_ZERO); 2247 marker->b_flags |= B_MARKER; 2248 marker->b_qindex = BQUEUE_NONE; 2249 marker->b_qcpu = 0; 2250 2251 /* 2252 * This process needs to be suspended prior to shutdown sync. 2253 */ 2254 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc, 2255 td, SHUTDOWN_PRI_LAST); 2256 curthread->td_flags |= TDF_SYSTHREAD; 2257 2258 /* 2259 * This process is allowed to take the buffer cache to the limit 2260 */ 2261 for (;;) { 2262 kproc_suspend_loop(); 2263 2264 /* 2265 * Do the flush as long as the number of dirty buffers 2266 * (including those running) exceeds lodirtybufspace. 2267 * 2268 * When flushing limit running I/O to hirunningspace 2269 * Do the flush. Limit the amount of in-transit I/O we 2270 * allow to build up, otherwise we would completely saturate 2271 * the I/O system. Wakeup any waiting processes before we 2272 * normally would so they can run in parallel with our drain. 2273 * 2274 * Our aggregate normal+HW lo water mark is lodirtybufspace, 2275 * but because we split the operation into two threads we 2276 * have to cut it in half for each thread. 2277 */ 2278 waitrunningbufspace(); 2279 limit = lodirtybufspace / 2; 2280 while (buf_limit_fn(limit)) { 2281 if (flushbufqueues(marker, queue) == 0) 2282 break; 2283 if (runningbufspace < hirunningspace) 2284 continue; 2285 waitrunningbufspace(); 2286 } 2287 2288 /* 2289 * We reached our low water mark, reset the 2290 * request and sleep until we are needed again. 2291 * The sleep is just so the suspend code works. 2292 */ 2293 tsleep_interlock(bd_req, 0); 2294 if (atomic_swap_int(bd_req, 0) == 0) 2295 tsleep(bd_req, PINTERLOCKED, "psleep", hz); 2296 } 2297 /* NOT REACHED */ 2298 /*kfree(marker, M_BIOBUF);*/ 2299 } 2300 2301 static int 2302 buf_daemon_limit(long limit) 2303 { 2304 return (runningbufspace + dirtykvaspace > limit || 2305 dirtybufcount - dirtybufcounthw >= nbuf / 2); 2306 } 2307 2308 static int 2309 buf_daemon_hw_limit(long limit) 2310 { 2311 return (runningbufspace + dirtykvaspace > limit || 2312 dirtybufcounthw >= nbuf / 2); 2313 } 2314 2315 static void 2316 buf_daemon(void) 2317 { 2318 buf_daemon1(bufdaemon_td, BQUEUE_DIRTY, buf_daemon_limit, 2319 &bd_request); 2320 } 2321 2322 static void 2323 buf_daemon_hw(void) 2324 { 2325 buf_daemon1(bufdaemonhw_td, BQUEUE_DIRTY_HW, buf_daemon_hw_limit, 2326 &bd_request_hw); 2327 } 2328 2329 /* 2330 * Flush up to (flushperqueue) buffers in the dirty queue. Each cpu has a 2331 * localized version of the queue. Each call made to this function iterates 2332 * to another cpu. It is desireable to flush several buffers from the same 2333 * cpu's queue at once, as these are likely going to be linear. 2334 * 2335 * We must be careful to free up B_INVAL buffers instead of write them, which 2336 * NFS is particularly sensitive to. 2337 * 2338 * B_RELBUF may only be set by VFSs. We do set B_AGE to indicate that we 2339 * really want to try to get the buffer out and reuse it due to the write 2340 * load on the machine. 2341 * 2342 * We must lock the buffer in order to check its validity before we can mess 2343 * with its contents. spin isn't enough. 2344 */ 2345 static int 2346 flushbufqueues(struct buf *marker, bufq_type_t q) 2347 { 2348 struct bufpcpu *pcpu; 2349 struct buf *bp; 2350 int r = 0; 2351 u_int loops = flushperqueue; 2352 int lcpu = marker->b_qcpu; 2353 2354 KKASSERT(marker->b_qindex == BQUEUE_NONE); 2355 KKASSERT(marker->b_flags & B_MARKER); 2356 2357 again: 2358 /* 2359 * Spinlock needed to perform operations on the queue and may be 2360 * held through a non-blocking BUF_LOCK(), but cannot be held when 2361 * BUF_UNLOCK()ing or through any other major operation. 2362 */ 2363 pcpu = &bufpcpu[marker->b_qcpu]; 2364 spin_lock(&pcpu->spin); 2365 marker->b_qindex = q; 2366 TAILQ_INSERT_HEAD(&pcpu->bufqueues[q], marker, b_freelist); 2367 bp = marker; 2368 2369 while ((bp = TAILQ_NEXT(bp, b_freelist)) != NULL) { 2370 /* 2371 * NOTE: spinlock is always held at the top of the loop 2372 */ 2373 if (bp->b_flags & B_MARKER) 2374 continue; 2375 if ((bp->b_flags & B_DELWRI) == 0) { 2376 kprintf("Unexpected clean buffer %p\n", bp); 2377 continue; 2378 } 2379 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) 2380 continue; 2381 KKASSERT(bp->b_qcpu == marker->b_qcpu && bp->b_qindex == q); 2382 2383 /* 2384 * Once the buffer is locked we will have no choice but to 2385 * unlock the spinlock around a later BUF_UNLOCK and re-set 2386 * bp = marker when looping. Move the marker now to make 2387 * things easier. 2388 */ 2389 TAILQ_REMOVE(&pcpu->bufqueues[q], marker, b_freelist); 2390 TAILQ_INSERT_AFTER(&pcpu->bufqueues[q], bp, marker, b_freelist); 2391 2392 /* 2393 * Must recheck B_DELWRI after successfully locking 2394 * the buffer. 2395 */ 2396 if ((bp->b_flags & B_DELWRI) == 0) { 2397 spin_unlock(&pcpu->spin); 2398 BUF_UNLOCK(bp); 2399 spin_lock(&pcpu->spin); 2400 bp = marker; 2401 continue; 2402 } 2403 2404 /* 2405 * Remove the buffer from its queue. We still own the 2406 * spinlock here. 2407 */ 2408 _bremfree(bp); 2409 2410 /* 2411 * Disposing of an invalid buffer counts as a flush op 2412 */ 2413 if (bp->b_flags & B_INVAL) { 2414 spin_unlock(&pcpu->spin); 2415 brelse(bp); 2416 goto doloop; 2417 } 2418 2419 /* 2420 * Release the spinlock for the more complex ops we 2421 * are now going to do. 2422 */ 2423 spin_unlock(&pcpu->spin); 2424 lwkt_yield(); 2425 2426 /* 2427 * This is a bit messy 2428 */ 2429 if (LIST_FIRST(&bp->b_dep) != NULL && 2430 (bp->b_flags & B_DEFERRED) == 0 && 2431 buf_countdeps(bp, 0)) { 2432 spin_lock(&pcpu->spin); 2433 TAILQ_INSERT_TAIL(&pcpu->bufqueues[q], bp, b_freelist); 2434 bp->b_qindex = q; 2435 bp->b_flags |= B_DEFERRED; 2436 spin_unlock(&pcpu->spin); 2437 BUF_UNLOCK(bp); 2438 spin_lock(&pcpu->spin); 2439 bp = marker; 2440 continue; 2441 } 2442 2443 /* 2444 * spinlock not held here. 2445 * 2446 * If the buffer has a dependancy, buf_checkwrite() must 2447 * also return 0 for us to be able to initate the write. 2448 * 2449 * If the buffer is flagged B_ERROR it may be requeued 2450 * over and over again, we try to avoid a live lock. 2451 */ 2452 if (LIST_FIRST(&bp->b_dep) != NULL && buf_checkwrite(bp)) { 2453 brelse(bp); 2454 } else if (bp->b_flags & B_ERROR) { 2455 tsleep(bp, 0, "bioer", 1); 2456 bp->b_flags &= ~B_AGE; 2457 cluster_awrite(bp); 2458 } else { 2459 bp->b_flags |= B_AGE | B_KVABIO; 2460 cluster_awrite(bp); 2461 } 2462 /* bp invalid but needs to be NULL-tested if we break out */ 2463 doloop: 2464 spin_lock(&pcpu->spin); 2465 ++r; 2466 if (--loops == 0) 2467 break; 2468 bp = marker; 2469 } 2470 /* bp is invalid here but can be NULL-tested to advance */ 2471 2472 TAILQ_REMOVE(&pcpu->bufqueues[q], marker, b_freelist); 2473 marker->b_qindex = BQUEUE_NONE; 2474 spin_unlock(&pcpu->spin); 2475 2476 /* 2477 * Advance the marker to be fair. 2478 */ 2479 marker->b_qcpu = (marker->b_qcpu + 1) % ncpus; 2480 if (bp == NULL) { 2481 if (marker->b_qcpu != lcpu) 2482 goto again; 2483 } 2484 2485 return (r); 2486 } 2487 2488 /* 2489 * inmem: 2490 * 2491 * Returns true if no I/O is needed to access the associated VM object. 2492 * This is like findblk except it also hunts around in the VM system for 2493 * the data. 2494 * 2495 * Note that we ignore vm_page_free() races from interrupts against our 2496 * lookup, since if the caller is not protected our return value will not 2497 * be any more valid then otherwise once we exit the critical section. 2498 */ 2499 int 2500 inmem(struct vnode *vp, off_t loffset) 2501 { 2502 vm_object_t obj; 2503 vm_offset_t toff, tinc, size; 2504 vm_page_t m; 2505 int res = 1; 2506 2507 if (findblk(vp, loffset, FINDBLK_TEST)) 2508 return 1; 2509 if (vp->v_mount == NULL) 2510 return 0; 2511 if ((obj = vp->v_object) == NULL) 2512 return 0; 2513 2514 size = PAGE_SIZE; 2515 if (size > vp->v_mount->mnt_stat.f_iosize) 2516 size = vp->v_mount->mnt_stat.f_iosize; 2517 2518 vm_object_hold(obj); 2519 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2520 m = vm_page_lookup(obj, OFF_TO_IDX(loffset + toff)); 2521 if (m == NULL) { 2522 res = 0; 2523 break; 2524 } 2525 tinc = size; 2526 if (tinc > PAGE_SIZE - ((toff + loffset) & PAGE_MASK)) 2527 tinc = PAGE_SIZE - ((toff + loffset) & PAGE_MASK); 2528 if (vm_page_is_valid(m, 2529 (vm_offset_t) ((toff + loffset) & PAGE_MASK), tinc) == 0) { 2530 res = 0; 2531 break; 2532 } 2533 } 2534 vm_object_drop(obj); 2535 return (res); 2536 } 2537 2538 /* 2539 * findblk: 2540 * 2541 * Locate and return the specified buffer. Unless flagged otherwise, 2542 * a locked buffer will be returned if it exists or NULL if it does not. 2543 * 2544 * findblk()'d buffers are still on the bufqueues and if you intend 2545 * to use your (locked NON-TEST) buffer you need to bremfree(bp) 2546 * and possibly do other stuff to it. 2547 * 2548 * FINDBLK_TEST - Do not lock the buffer. The caller is responsible 2549 * for locking the buffer and ensuring that it remains 2550 * the desired buffer after locking. 2551 * 2552 * FINDBLK_NBLOCK - Lock the buffer non-blocking. If we are unable 2553 * to acquire the lock we return NULL, even if the 2554 * buffer exists. 2555 * 2556 * FINDBLK_REF - Returns the buffer ref'd, which prevents normal 2557 * reuse by getnewbuf() but does not prevent 2558 * disassociation (B_INVAL). Used to avoid deadlocks 2559 * against random (vp,loffset)s due to reassignment. 2560 * 2561 * FINDBLK_KVABIO - Only applicable when returning a locked buffer. 2562 * Indicates that the caller supports B_KVABIO. 2563 * 2564 * (0) - Lock the buffer blocking. 2565 */ 2566 struct buf * 2567 findblk(struct vnode *vp, off_t loffset, int flags) 2568 { 2569 struct buf *bp; 2570 int lkflags; 2571 2572 lkflags = LK_EXCLUSIVE; 2573 if (flags & FINDBLK_NBLOCK) 2574 lkflags |= LK_NOWAIT; 2575 2576 for (;;) { 2577 /* 2578 * Lookup. Ref the buf while holding v_token to prevent 2579 * reuse (but does not prevent diassociation). 2580 */ 2581 lwkt_gettoken_shared(&vp->v_token); 2582 bp = buf_rb_hash_RB_LOOKUP(&vp->v_rbhash_tree, loffset); 2583 if (bp == NULL) { 2584 lwkt_reltoken(&vp->v_token); 2585 return(NULL); 2586 } 2587 bqhold(bp); 2588 lwkt_reltoken(&vp->v_token); 2589 2590 /* 2591 * If testing only break and return bp, do not lock. 2592 */ 2593 if (flags & FINDBLK_TEST) 2594 break; 2595 2596 /* 2597 * Lock the buffer, return an error if the lock fails. 2598 * (only FINDBLK_NBLOCK can cause the lock to fail). 2599 */ 2600 if (BUF_LOCK(bp, lkflags)) { 2601 atomic_subtract_int(&bp->b_refs, 1); 2602 /* bp = NULL; not needed */ 2603 return(NULL); 2604 } 2605 2606 /* 2607 * Revalidate the locked buf before allowing it to be 2608 * returned. 2609 * 2610 * B_KVABIO is only set/cleared when locking. When 2611 * clearing B_KVABIO, we must ensure that the buffer 2612 * is synchronized to all cpus. 2613 */ 2614 if (bp->b_vp == vp && bp->b_loffset == loffset) { 2615 if (flags & FINDBLK_KVABIO) 2616 bp->b_flags |= B_KVABIO; 2617 else 2618 bkvasync_all(bp); 2619 break; 2620 } 2621 atomic_subtract_int(&bp->b_refs, 1); 2622 BUF_UNLOCK(bp); 2623 } 2624 2625 /* 2626 * Success 2627 */ 2628 if ((flags & FINDBLK_REF) == 0) 2629 atomic_subtract_int(&bp->b_refs, 1); 2630 return(bp); 2631 } 2632 2633 /* 2634 * getcacheblk: 2635 * 2636 * Similar to getblk() except only returns the buffer if it is 2637 * B_CACHE and requires no other manipulation. Otherwise NULL 2638 * is returned. NULL is also returned if GETBLK_NOWAIT is set 2639 * and the getblk() would block. 2640 * 2641 * If B_RAM is set the buffer might be just fine, but we return 2642 * NULL anyway because we want the code to fall through to the 2643 * cluster read to issue more read-aheads. Otherwise read-ahead breaks. 2644 * 2645 * If blksize is 0 the buffer cache buffer must already be fully 2646 * cached. 2647 * 2648 * If blksize is non-zero getblk() will be used, allowing a buffer 2649 * to be reinstantiated from its VM backing store. The buffer must 2650 * still be fully cached after reinstantiation to be returned. 2651 */ 2652 struct buf * 2653 getcacheblk(struct vnode *vp, off_t loffset, int blksize, int blkflags) 2654 { 2655 struct buf *bp; 2656 int fndflags = 0; 2657 2658 if (blkflags & GETBLK_NOWAIT) 2659 fndflags |= FINDBLK_NBLOCK; 2660 if (blkflags & GETBLK_KVABIO) 2661 fndflags |= FINDBLK_KVABIO; 2662 2663 if (blksize) { 2664 bp = getblk(vp, loffset, blksize, blkflags, 0); 2665 if (bp) { 2666 if ((bp->b_flags & (B_INVAL | B_CACHE)) == B_CACHE) { 2667 bp->b_flags &= ~B_AGE; 2668 if (bp->b_flags & B_RAM) { 2669 bqrelse(bp); 2670 bp = NULL; 2671 } 2672 } else { 2673 brelse(bp); 2674 bp = NULL; 2675 } 2676 } 2677 } else { 2678 bp = findblk(vp, loffset, fndflags); 2679 if (bp) { 2680 if ((bp->b_flags & (B_INVAL | B_CACHE | B_RAM)) == 2681 B_CACHE) { 2682 bp->b_flags &= ~B_AGE; 2683 bremfree(bp); 2684 } else { 2685 BUF_UNLOCK(bp); 2686 bp = NULL; 2687 } 2688 } 2689 } 2690 return (bp); 2691 } 2692 2693 /* 2694 * getblk: 2695 * 2696 * Get a block given a specified block and offset into a file/device. 2697 * B_INVAL may or may not be set on return. The caller should clear 2698 * B_INVAL prior to initiating a READ. 2699 * 2700 * IT IS IMPORTANT TO UNDERSTAND THAT IF YOU CALL GETBLK() AND B_CACHE 2701 * IS NOT SET, YOU MUST INITIALIZE THE RETURNED BUFFER, ISSUE A READ, 2702 * OR SET B_INVAL BEFORE RETIRING IT. If you retire a getblk'd buffer 2703 * without doing any of those things the system will likely believe 2704 * the buffer to be valid (especially if it is not B_VMIO), and the 2705 * next getblk() will return the buffer with B_CACHE set. 2706 * 2707 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2708 * an existing buffer. 2709 * 2710 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2711 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2712 * and then cleared based on the backing VM. If the previous buffer is 2713 * non-0-sized but invalid, B_CACHE will be cleared. 2714 * 2715 * If getblk() must create a new buffer, the new buffer is returned with 2716 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2717 * case it is returned with B_INVAL clear and B_CACHE set based on the 2718 * backing VM. 2719 * 2720 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 2721 * B_CACHE bit is clear. 2722 * 2723 * What this means, basically, is that the caller should use B_CACHE to 2724 * determine whether the buffer is fully valid or not and should clear 2725 * B_INVAL prior to issuing a read. If the caller intends to validate 2726 * the buffer by loading its data area with something, the caller needs 2727 * to clear B_INVAL. If the caller does this without issuing an I/O, 2728 * the caller should set B_CACHE ( as an optimization ), else the caller 2729 * should issue the I/O and biodone() will set B_CACHE if the I/O was 2730 * a write attempt or if it was a successfull read. If the caller 2731 * intends to issue a READ, the caller must clear B_INVAL and B_ERROR 2732 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 2733 * 2734 * getblk flags: 2735 * 2736 * GETBLK_PCATCH - catch signal if blocked, can cause NULL return 2737 * GETBLK_BHEAVY - heavy-weight buffer cache buffer 2738 */ 2739 struct buf * 2740 getblk(struct vnode *vp, off_t loffset, int size, int blkflags, int slptimeo) 2741 { 2742 struct buf *bp; 2743 int slpflags = (blkflags & GETBLK_PCATCH) ? PCATCH : 0; 2744 int error; 2745 int lkflags; 2746 2747 if (size > MAXBSIZE) 2748 panic("getblk: size(%d) > MAXBSIZE(%d)", size, MAXBSIZE); 2749 if (vp->v_object == NULL) 2750 panic("getblk: vnode %p has no object!", vp); 2751 2752 /* 2753 * NOTE: findblk does not try to resolve KVABIO in REF-only mode. 2754 * we still have to handle that ourselves. 2755 */ 2756 loop: 2757 if ((bp = findblk(vp, loffset, FINDBLK_REF | FINDBLK_TEST)) != NULL) { 2758 /* 2759 * The buffer was found in the cache, but we need to lock it. 2760 * We must acquire a ref on the bp to prevent reuse, but 2761 * this will not prevent disassociation (brelvp()) so we 2762 * must recheck (vp,loffset) after acquiring the lock. 2763 * 2764 * Without the ref the buffer could potentially be reused 2765 * before we acquire the lock and create a deadlock 2766 * situation between the thread trying to reuse the buffer 2767 * and us due to the fact that we would wind up blocking 2768 * on a random (vp,loffset). 2769 */ 2770 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) { 2771 if (blkflags & GETBLK_NOWAIT) { 2772 bqdrop(bp); 2773 return(NULL); 2774 } 2775 lkflags = LK_EXCLUSIVE | LK_SLEEPFAIL; 2776 if (blkflags & GETBLK_PCATCH) 2777 lkflags |= LK_PCATCH; 2778 error = BUF_TIMELOCK(bp, lkflags, "getblk", slptimeo); 2779 if (error) { 2780 bqdrop(bp); 2781 if (error == ENOLCK) 2782 goto loop; 2783 return (NULL); 2784 } 2785 /* buffer may have changed on us */ 2786 } 2787 bqdrop(bp); 2788 2789 /* 2790 * Once the buffer has been locked, make sure we didn't race 2791 * a buffer recyclement. Buffers that are no longer hashed 2792 * will have b_vp == NULL, so this takes care of that check 2793 * as well. 2794 */ 2795 if (bp->b_vp != vp || bp->b_loffset != loffset) { 2796 #if 0 2797 kprintf("Warning buffer %p (vp %p loffset %lld) " 2798 "was recycled\n", 2799 bp, vp, (long long)loffset); 2800 #endif 2801 BUF_UNLOCK(bp); 2802 goto loop; 2803 } 2804 2805 /* 2806 * If SZMATCH any pre-existing buffer must be of the requested 2807 * size or NULL is returned. The caller absolutely does not 2808 * want getblk() to bwrite() the buffer on a size mismatch. 2809 */ 2810 if ((blkflags & GETBLK_SZMATCH) && size != bp->b_bcount) { 2811 BUF_UNLOCK(bp); 2812 return(NULL); 2813 } 2814 2815 /* 2816 * All vnode-based buffers must be backed by a VM object. 2817 * 2818 * Set B_KVABIO for any incidental work, we will fix it 2819 * up later. 2820 */ 2821 KKASSERT(bp->b_flags & B_VMIO); 2822 KKASSERT(bp->b_cmd == BUF_CMD_DONE); 2823 bp->b_flags &= ~B_AGE; 2824 bp->b_flags |= B_KVABIO; 2825 2826 /* 2827 * Make sure that B_INVAL buffers do not have a cached 2828 * block number translation. 2829 */ 2830 if ((bp->b_flags & B_INVAL) && 2831 (bp->b_bio2.bio_offset != NOOFFSET)) { 2832 kprintf("Warning invalid buffer %p (vp %p loffset %lld)" 2833 " did not have cleared bio_offset cache\n", 2834 bp, vp, (long long)loffset); 2835 clearbiocache(&bp->b_bio2); 2836 } 2837 2838 /* 2839 * The buffer is locked. B_CACHE is cleared if the buffer is 2840 * invalid. 2841 * 2842 * After the bremfree(), disposals must use b[q]relse(). 2843 */ 2844 if (bp->b_flags & B_INVAL) 2845 bp->b_flags &= ~B_CACHE; 2846 bremfree(bp); 2847 2848 /* 2849 * Any size inconsistancy with a dirty buffer or a buffer 2850 * with a softupdates dependancy must be resolved. Resizing 2851 * the buffer in such circumstances can lead to problems. 2852 * 2853 * Dirty or dependant buffers are written synchronously. 2854 * Other types of buffers are simply released and 2855 * reconstituted as they may be backed by valid, dirty VM 2856 * pages (but not marked B_DELWRI). 2857 * 2858 * NFS NOTE: NFS buffers which straddle EOF are oddly-sized 2859 * and may be left over from a prior truncation (and thus 2860 * no longer represent the actual EOF point), so we 2861 * definitely do not want to B_NOCACHE the backing store. 2862 */ 2863 if (size != bp->b_bcount) { 2864 if (bp->b_flags & B_DELWRI) { 2865 bp->b_flags |= B_RELBUF; 2866 bwrite(bp); 2867 } else if (LIST_FIRST(&bp->b_dep)) { 2868 bp->b_flags |= B_RELBUF; 2869 bwrite(bp); 2870 } else { 2871 bp->b_flags |= B_RELBUF; 2872 brelse(bp); 2873 } 2874 goto loop; 2875 } 2876 KKASSERT(size <= bp->b_kvasize); 2877 KASSERT(bp->b_loffset != NOOFFSET, 2878 ("getblk: no buffer offset")); 2879 2880 /* 2881 * A buffer with B_DELWRI set and B_CACHE clear must 2882 * be committed before we can return the buffer in 2883 * order to prevent the caller from issuing a read 2884 * ( due to B_CACHE not being set ) and overwriting 2885 * it. 2886 * 2887 * Most callers, including NFS and FFS, need this to 2888 * operate properly either because they assume they 2889 * can issue a read if B_CACHE is not set, or because 2890 * ( for example ) an uncached B_DELWRI might loop due 2891 * to softupdates re-dirtying the buffer. In the latter 2892 * case, B_CACHE is set after the first write completes, 2893 * preventing further loops. 2894 * 2895 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 2896 * above while extending the buffer, we cannot allow the 2897 * buffer to remain with B_CACHE set after the write 2898 * completes or it will represent a corrupt state. To 2899 * deal with this we set B_NOCACHE to scrap the buffer 2900 * after the write. 2901 * 2902 * XXX Should this be B_RELBUF instead of B_NOCACHE? 2903 * I'm not even sure this state is still possible 2904 * now that getblk() writes out any dirty buffers 2905 * on size changes. 2906 * 2907 * We might be able to do something fancy, like setting 2908 * B_CACHE in bwrite() except if B_DELWRI is already set, 2909 * so the below call doesn't set B_CACHE, but that gets real 2910 * confusing. This is much easier. 2911 */ 2912 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 2913 kprintf("getblk: Warning, bp %p loff=%jx DELWRI set " 2914 "and CACHE clear, b_flags %08x\n", 2915 bp, (uintmax_t)bp->b_loffset, bp->b_flags); 2916 bp->b_flags |= B_NOCACHE; 2917 bwrite(bp); 2918 goto loop; 2919 } 2920 } else { 2921 /* 2922 * Buffer is not in-core, create new buffer. The buffer 2923 * returned by getnewbuf() is locked. Note that the returned 2924 * buffer is also considered valid (not marked B_INVAL). 2925 * 2926 * Calculating the offset for the I/O requires figuring out 2927 * the block size. We use DEV_BSIZE for VBLK or VCHR and 2928 * the mount's f_iosize otherwise. If the vnode does not 2929 * have an associated mount we assume that the passed size is 2930 * the block size. 2931 * 2932 * Note that vn_isdisk() cannot be used here since it may 2933 * return a failure for numerous reasons. Note that the 2934 * buffer size may be larger then the block size (the caller 2935 * will use block numbers with the proper multiple). Beware 2936 * of using any v_* fields which are part of unions. In 2937 * particular, in DragonFly the mount point overloading 2938 * mechanism uses the namecache only and the underlying 2939 * directory vnode is not a special case. 2940 */ 2941 int bsize, maxsize; 2942 2943 if (vp->v_type == VBLK || vp->v_type == VCHR) 2944 bsize = DEV_BSIZE; 2945 else if (vp->v_mount) 2946 bsize = vp->v_mount->mnt_stat.f_iosize; 2947 else 2948 bsize = size; 2949 2950 maxsize = size + (loffset & PAGE_MASK); 2951 maxsize = imax(maxsize, bsize); 2952 2953 bp = getnewbuf(blkflags, slptimeo, size, maxsize); 2954 if (bp == NULL) { 2955 if (slpflags || slptimeo) 2956 return NULL; 2957 goto loop; 2958 } 2959 2960 /* 2961 * Atomically insert the buffer into the hash, so that it can 2962 * be found by findblk(). 2963 * 2964 * If bgetvp() returns non-zero a collision occured, and the 2965 * bp will not be associated with the vnode. 2966 * 2967 * Make sure the translation layer has been cleared. 2968 */ 2969 bp->b_loffset = loffset; 2970 bp->b_bio2.bio_offset = NOOFFSET; 2971 /* bp->b_bio2.bio_next = NULL; */ 2972 2973 if (bgetvp(vp, bp, size)) { 2974 bp->b_flags |= B_INVAL; 2975 brelse(bp); 2976 goto loop; 2977 } 2978 2979 /* 2980 * All vnode-based buffers must be backed by a VM object. 2981 * 2982 * Set B_KVABIO for incidental work 2983 */ 2984 KKASSERT(vp->v_object != NULL); 2985 bp->b_flags |= B_VMIO | B_KVABIO; 2986 KKASSERT(bp->b_cmd == BUF_CMD_DONE); 2987 2988 allocbuf(bp, size); 2989 } 2990 2991 /* 2992 * Do the nasty smp broadcast (if the buffer needs it) when KVABIO 2993 * is not supported. 2994 */ 2995 if (bp && (blkflags & GETBLK_KVABIO) == 0) { 2996 bkvasync_all(bp); 2997 } 2998 return (bp); 2999 } 3000 3001 /* 3002 * regetblk(bp) 3003 * 3004 * Reacquire a buffer that was previously released to the locked queue, 3005 * or reacquire a buffer which is interlocked by having bioops->io_deallocate 3006 * set B_LOCKED (which handles the acquisition race). 3007 * 3008 * To this end, either B_LOCKED must be set or the dependancy list must be 3009 * non-empty. 3010 */ 3011 void 3012 regetblk(struct buf *bp) 3013 { 3014 KKASSERT((bp->b_flags & B_LOCKED) || LIST_FIRST(&bp->b_dep) != NULL); 3015 BUF_LOCK(bp, LK_EXCLUSIVE | LK_RETRY); 3016 bremfree(bp); 3017 } 3018 3019 /* 3020 * allocbuf: 3021 * 3022 * This code constitutes the buffer memory from either anonymous system 3023 * memory (in the case of non-VMIO operations) or from an associated 3024 * VM object (in the case of VMIO operations). This code is able to 3025 * resize a buffer up or down. 3026 * 3027 * Note that this code is tricky, and has many complications to resolve 3028 * deadlock or inconsistant data situations. Tread lightly!!! 3029 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 3030 * the caller. Calling this code willy nilly can result in the loss of 3031 * data. 3032 * 3033 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 3034 * B_CACHE for the non-VMIO case. 3035 * 3036 * This routine does not need to be called from a critical section but you 3037 * must own the buffer. 3038 */ 3039 void 3040 allocbuf(struct buf *bp, int size) 3041 { 3042 vm_page_t m; 3043 int newbsize; 3044 int desiredpages; 3045 int i; 3046 3047 if (BUF_LOCKINUSE(bp) == 0) 3048 panic("allocbuf: buffer not busy"); 3049 3050 if (bp->b_kvasize < size) 3051 panic("allocbuf: buffer too small"); 3052 3053 KKASSERT(bp->b_flags & B_VMIO); 3054 3055 newbsize = roundup2(size, DEV_BSIZE); 3056 desiredpages = ((int)(bp->b_loffset & PAGE_MASK) + 3057 newbsize + PAGE_MASK) >> PAGE_SHIFT; 3058 KKASSERT(desiredpages <= XIO_INTERNAL_PAGES); 3059 3060 /* 3061 * Set B_CACHE initially if buffer is 0 length or will become 3062 * 0-length. 3063 */ 3064 if (size == 0 || bp->b_bufsize == 0) 3065 bp->b_flags |= B_CACHE; 3066 3067 if (newbsize < bp->b_bufsize) { 3068 /* 3069 * DEV_BSIZE aligned new buffer size is less then the 3070 * DEV_BSIZE aligned existing buffer size. Figure out 3071 * if we have to remove any pages. 3072 */ 3073 if (desiredpages < bp->b_xio.xio_npages) { 3074 for (i = desiredpages; i < bp->b_xio.xio_npages; i++) { 3075 /* 3076 * the page is not freed here -- it 3077 * is the responsibility of 3078 * vnode_pager_setsize 3079 */ 3080 m = bp->b_xio.xio_pages[i]; 3081 KASSERT(m != bogus_page, 3082 ("allocbuf: bogus page found")); 3083 vm_page_busy_wait(m, TRUE, "biodep"); 3084 bp->b_xio.xio_pages[i] = NULL; 3085 vm_page_unwire(m, 0); 3086 vm_page_wakeup(m); 3087 } 3088 pmap_qremove_noinval((vm_offset_t) 3089 trunc_page((vm_offset_t)bp->b_data) + 3090 (desiredpages << PAGE_SHIFT), 3091 (bp->b_xio.xio_npages - desiredpages)); 3092 bp->b_xio.xio_npages = desiredpages; 3093 3094 /* 3095 * Don't bother invalidating the pmap changes 3096 * (which wastes global SMP invalidation IPIs) 3097 * when setting the size to 0. This case occurs 3098 * when called via getnewbuf() during buffer 3099 * recyclement. 3100 */ 3101 if (desiredpages == 0) { 3102 CPUMASK_ASSZERO(bp->b_cpumask); 3103 } else { 3104 bkvareset(bp); 3105 } 3106 } 3107 } else if (size > bp->b_bcount) { 3108 /* 3109 * We are growing the buffer, possibly in a 3110 * byte-granular fashion. 3111 */ 3112 struct vnode *vp; 3113 vm_object_t obj; 3114 vm_offset_t toff; 3115 vm_offset_t tinc; 3116 3117 /* 3118 * Step 1, bring in the VM pages from the object, 3119 * allocating them if necessary. We must clear 3120 * B_CACHE if these pages are not valid for the 3121 * range covered by the buffer. 3122 */ 3123 vp = bp->b_vp; 3124 obj = vp->v_object; 3125 3126 vm_object_hold(obj); 3127 while (bp->b_xio.xio_npages < desiredpages) { 3128 vm_page_t m; 3129 vm_pindex_t pi; 3130 int error; 3131 3132 pi = OFF_TO_IDX(bp->b_loffset) + 3133 bp->b_xio.xio_npages; 3134 3135 /* 3136 * Blocking on m->busy_count might lead to a 3137 * deadlock: 3138 * 3139 * vm_fault->getpages->cluster_read->allocbuf 3140 */ 3141 m = vm_page_lookup_busy_try(obj, pi, FALSE, 3142 &error); 3143 if (error) { 3144 vm_page_sleep_busy(m, FALSE, "pgtblk"); 3145 continue; 3146 } 3147 if (m == NULL) { 3148 /* 3149 * note: must allocate system pages 3150 * since blocking here could intefere 3151 * with paging I/O, no matter which 3152 * process we are. 3153 */ 3154 m = bio_page_alloc(bp, obj, pi, 3155 desiredpages - 3156 bp->b_xio.xio_npages); 3157 if (m) { 3158 vm_page_wire(m); 3159 vm_page_wakeup(m); 3160 bp->b_flags &= ~B_CACHE; 3161 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 3162 ++bp->b_xio.xio_npages; 3163 } 3164 continue; 3165 } 3166 3167 /* 3168 * We found a page and were able to busy it. 3169 */ 3170 vm_page_wire(m); 3171 vm_page_wakeup(m); 3172 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 3173 ++bp->b_xio.xio_npages; 3174 if (bp->b_act_count < m->act_count) 3175 bp->b_act_count = m->act_count; 3176 } 3177 vm_object_drop(obj); 3178 3179 /* 3180 * Step 2. We've loaded the pages into the buffer, 3181 * we have to figure out if we can still have B_CACHE 3182 * set. Note that B_CACHE is set according to the 3183 * byte-granular range ( bcount and size ), not the 3184 * aligned range ( newbsize ). 3185 * 3186 * The VM test is against m->valid, which is DEV_BSIZE 3187 * aligned. Needless to say, the validity of the data 3188 * needs to also be DEV_BSIZE aligned. Note that this 3189 * fails with NFS if the server or some other client 3190 * extends the file's EOF. If our buffer is resized, 3191 * B_CACHE may remain set! XXX 3192 */ 3193 3194 toff = bp->b_bcount; 3195 tinc = PAGE_SIZE - ((bp->b_loffset + toff) & PAGE_MASK); 3196 3197 while ((bp->b_flags & B_CACHE) && toff < size) { 3198 vm_pindex_t pi; 3199 3200 if (tinc > (size - toff)) 3201 tinc = size - toff; 3202 3203 pi = ((bp->b_loffset & PAGE_MASK) + toff) >> 3204 PAGE_SHIFT; 3205 3206 vfs_buf_test_cache( 3207 bp, 3208 bp->b_loffset, 3209 toff, 3210 tinc, 3211 bp->b_xio.xio_pages[pi] 3212 ); 3213 toff += tinc; 3214 tinc = PAGE_SIZE; 3215 } 3216 3217 /* 3218 * Step 3, fixup the KVM pmap. Remember that 3219 * bp->b_data is relative to bp->b_loffset, but 3220 * bp->b_loffset may be offset into the first page. 3221 */ 3222 bp->b_data = (caddr_t)trunc_page((vm_offset_t)bp->b_data); 3223 pmap_qenter_noinval((vm_offset_t)bp->b_data, 3224 bp->b_xio.xio_pages, bp->b_xio.xio_npages); 3225 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 3226 (vm_offset_t)(bp->b_loffset & PAGE_MASK)); 3227 bkvareset(bp); 3228 } 3229 atomic_add_long(&bufspace, newbsize - bp->b_bufsize); 3230 3231 /* adjust space use on already-dirty buffer */ 3232 if (bp->b_flags & B_DELWRI) { 3233 /* dirtykvaspace unchanged */ 3234 atomic_add_long(&dirtybufspace, newbsize - bp->b_bufsize); 3235 if (bp->b_flags & B_HEAVY) { 3236 atomic_add_long(&dirtybufspacehw, 3237 newbsize - bp->b_bufsize); 3238 } 3239 } 3240 bp->b_bufsize = newbsize; /* actual buffer allocation */ 3241 bp->b_bcount = size; /* requested buffer size */ 3242 bufspacewakeup(); 3243 } 3244 3245 /* 3246 * biowait: 3247 * 3248 * Wait for buffer I/O completion, returning error status. B_EINTR 3249 * is converted into an EINTR error but not cleared (since a chain 3250 * of biowait() calls may occur). 3251 * 3252 * On return bpdone() will have been called but the buffer will remain 3253 * locked and will not have been brelse()'d. 3254 * 3255 * NOTE! If a timeout is specified and ETIMEDOUT occurs the I/O is 3256 * likely still in progress on return. 3257 * 3258 * NOTE! This operation is on a BIO, not a BUF. 3259 * 3260 * NOTE! BIO_DONE is cleared by vn_strategy() 3261 */ 3262 static __inline int 3263 _biowait(struct bio *bio, const char *wmesg, int to) 3264 { 3265 struct buf *bp = bio->bio_buf; 3266 u_int32_t flags; 3267 u_int32_t nflags; 3268 int error; 3269 3270 KKASSERT(bio == &bp->b_bio1); 3271 for (;;) { 3272 flags = bio->bio_flags; 3273 if (flags & BIO_DONE) 3274 break; 3275 nflags = flags | BIO_WANT; 3276 tsleep_interlock(bio, 0); 3277 if (atomic_cmpset_int(&bio->bio_flags, flags, nflags)) { 3278 if (wmesg) 3279 error = tsleep(bio, PINTERLOCKED, wmesg, to); 3280 else if (bp->b_cmd == BUF_CMD_READ) 3281 error = tsleep(bio, PINTERLOCKED, "biord", to); 3282 else 3283 error = tsleep(bio, PINTERLOCKED, "biowr", to); 3284 if (error) { 3285 kprintf("tsleep error biowait %d\n", error); 3286 return (error); 3287 } 3288 } 3289 } 3290 3291 /* 3292 * Finish up. 3293 */ 3294 KKASSERT(bp->b_cmd == BUF_CMD_DONE); 3295 bio->bio_flags &= ~(BIO_DONE | BIO_SYNC); 3296 if (bp->b_flags & B_EINTR) 3297 return (EINTR); 3298 if (bp->b_flags & B_ERROR) 3299 return (bp->b_error ? bp->b_error : EIO); 3300 return (0); 3301 } 3302 3303 int 3304 biowait(struct bio *bio, const char *wmesg) 3305 { 3306 return(_biowait(bio, wmesg, 0)); 3307 } 3308 3309 int 3310 biowait_timeout(struct bio *bio, const char *wmesg, int to) 3311 { 3312 return(_biowait(bio, wmesg, to)); 3313 } 3314 3315 /* 3316 * This associates a tracking count with an I/O. vn_strategy() and 3317 * dev_dstrategy() do this automatically but there are a few cases 3318 * where a vnode or device layer is bypassed when a block translation 3319 * is cached. In such cases bio_start_transaction() may be called on 3320 * the bypassed layers so the system gets an I/O in progress indication 3321 * for those higher layers. 3322 */ 3323 void 3324 bio_start_transaction(struct bio *bio, struct bio_track *track) 3325 { 3326 bio->bio_track = track; 3327 bio_track_ref(track); 3328 dsched_buf_enter(bio->bio_buf); /* might stack */ 3329 } 3330 3331 /* 3332 * Initiate I/O on a vnode. 3333 * 3334 * SWAPCACHE OPERATION: 3335 * 3336 * Real buffer cache buffers have a non-NULL bp->b_vp. Unfortunately 3337 * devfs also uses b_vp for fake buffers so we also have to check 3338 * that B_PAGING is 0. In this case the passed 'vp' is probably the 3339 * underlying block device. The swap assignments are related to the 3340 * buffer cache buffer's b_vp, not the passed vp. 3341 * 3342 * The passed vp == bp->b_vp only in the case where the strategy call 3343 * is made on the vp itself for its own buffers (a regular file or 3344 * block device vp). The filesystem usually then re-calls vn_strategy() 3345 * after translating the request to an underlying device. 3346 * 3347 * Cluster buffers set B_CLUSTER and the passed vp is the vp of the 3348 * underlying buffer cache buffers. 3349 * 3350 * We can only deal with page-aligned buffers at the moment, because 3351 * we can't tell what the real dirty state for pages straddling a buffer 3352 * are. 3353 * 3354 * In order to call swap_pager_strategy() we must provide the VM object 3355 * and base offset for the underlying buffer cache pages so it can find 3356 * the swap blocks. 3357 */ 3358 void 3359 vn_strategy(struct vnode *vp, struct bio *bio) 3360 { 3361 struct bio_track *track; 3362 struct buf *bp = bio->bio_buf; 3363 3364 KKASSERT(bp->b_cmd != BUF_CMD_DONE); 3365 3366 /* 3367 * Set when an I/O is issued on the bp. Cleared by consumers 3368 * (aka HAMMER), allowing the consumer to determine if I/O had 3369 * actually occurred. 3370 */ 3371 bp->b_flags |= B_IOISSUED; 3372 3373 /* 3374 * Handle the swapcache intercept. 3375 * 3376 * NOTE: The swapcache itself always supports KVABIO and will 3377 * do the right thing if its underlying devices do not. 3378 */ 3379 if (vn_cache_strategy(vp, bio)) 3380 return; 3381 3382 /* 3383 * If the vnode does not support KVABIO and the buffer is using 3384 * KVABIO, we must synchronize b_data to all cpus before dispatching. 3385 */ 3386 if ((vp->v_flag & VKVABIO) == 0 && (bp->b_flags & B_KVABIO)) 3387 bkvasync_all(bp); 3388 3389 /* 3390 * Otherwise do the operation through the filesystem 3391 */ 3392 if (bp->b_cmd == BUF_CMD_READ) 3393 track = &vp->v_track_read; 3394 else 3395 track = &vp->v_track_write; 3396 KKASSERT((bio->bio_flags & BIO_DONE) == 0); 3397 bio->bio_track = track; 3398 bio_track_ref(track); 3399 dsched_buf_enter(bp); /* might stack */ 3400 vop_strategy(*vp->v_ops, vp, bio); 3401 } 3402 3403 /* 3404 * vn_cache_strategy() 3405 * 3406 * Returns 1 if the interrupt was successful, 0 if not. 3407 * 3408 * NOTE: This function supports the KVABIO API wherein b_data might not 3409 * be synchronized to the current cpu. 3410 */ 3411 static void vn_cache_strategy_callback(struct bio *bio); 3412 3413 int 3414 vn_cache_strategy(struct vnode *vp, struct bio *bio) 3415 { 3416 struct buf *bp = bio->bio_buf; 3417 struct bio *nbio; 3418 vm_object_t object; 3419 vm_page_t m; 3420 int i; 3421 3422 /* 3423 * Stop using swapcache if paniced, dumping, or dumped 3424 */ 3425 if (panicstr || dumping) 3426 return(0); 3427 3428 /* 3429 * Is this buffer cache buffer suitable for reading from 3430 * the swap cache? 3431 */ 3432 if (vm_swapcache_read_enable == 0 || 3433 bp->b_cmd != BUF_CMD_READ || 3434 ((bp->b_flags & B_CLUSTER) == 0 && 3435 (bp->b_vp == NULL || (bp->b_flags & B_PAGING))) || 3436 ((int)bp->b_loffset & PAGE_MASK) != 0 || 3437 (bp->b_bcount & PAGE_MASK) != 0) { 3438 return(0); 3439 } 3440 3441 /* 3442 * Figure out the original VM object (it will match the underlying 3443 * VM pages). Note that swap cached data uses page indices relative 3444 * to that object, not relative to bio->bio_offset. 3445 */ 3446 if (bp->b_flags & B_CLUSTER) 3447 object = vp->v_object; 3448 else 3449 object = bp->b_vp->v_object; 3450 3451 /* 3452 * In order to be able to use the swap cache all underlying VM 3453 * pages must be marked as such, and we can't have any bogus pages. 3454 */ 3455 for (i = 0; i < bp->b_xio.xio_npages; ++i) { 3456 m = bp->b_xio.xio_pages[i]; 3457 if ((m->flags & PG_SWAPPED) == 0) 3458 break; 3459 if (m == bogus_page) 3460 break; 3461 } 3462 3463 /* 3464 * If we are good then issue the I/O using swap_pager_strategy(). 3465 * 3466 * We can only do this if the buffer actually supports object-backed 3467 * I/O. If it doesn't npages will be 0. 3468 */ 3469 if (i && i == bp->b_xio.xio_npages) { 3470 m = bp->b_xio.xio_pages[0]; 3471 nbio = push_bio(bio); 3472 nbio->bio_done = vn_cache_strategy_callback; 3473 nbio->bio_offset = ptoa(m->pindex); 3474 KKASSERT(m->object == object); 3475 swap_pager_strategy(object, nbio); 3476 return(1); 3477 } 3478 return(0); 3479 } 3480 3481 /* 3482 * This is a bit of a hack but since the vn_cache_strategy() function can 3483 * override a VFS's strategy function we must make sure that the bio, which 3484 * is probably bio2, doesn't leak an unexpected offset value back to the 3485 * filesystem. The filesystem (e.g. UFS) might otherwise assume that the 3486 * bio went through its own file strategy function and the the bio2 offset 3487 * is a cached disk offset when, in fact, it isn't. 3488 */ 3489 static void 3490 vn_cache_strategy_callback(struct bio *bio) 3491 { 3492 bio->bio_offset = NOOFFSET; 3493 biodone(pop_bio(bio)); 3494 } 3495 3496 /* 3497 * bpdone: 3498 * 3499 * Finish I/O on a buffer after all BIOs have been processed. 3500 * Called when the bio chain is exhausted or by biowait. If called 3501 * by biowait, elseit is typically 0. 3502 * 3503 * bpdone is also responsible for setting B_CACHE in a B_VMIO bp. 3504 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3505 * assuming B_INVAL is clear. 3506 * 3507 * For the VMIO case, we set B_CACHE if the op was a read and no 3508 * read error occured, or if the op was a write. B_CACHE is never 3509 * set if the buffer is invalid or otherwise uncacheable. 3510 * 3511 * bpdone does not mess with B_INVAL, allowing the I/O routine or the 3512 * initiator to leave B_INVAL set to brelse the buffer out of existance 3513 * in the biodone routine. 3514 * 3515 * bpdone is responsible for calling bundirty() on the buffer after a 3516 * successful write. We previously did this prior to initiating the 3517 * write under the assumption that the buffer might be dirtied again 3518 * while the write was in progress, however doing it before-hand creates 3519 * a race condition prior to the call to vn_strategy() where the 3520 * filesystem may not be aware that a dirty buffer is present. 3521 * It should not be possible for the buffer or its underlying pages to 3522 * be redirtied prior to bpdone()'s unbusying of the underlying VM 3523 * pages. 3524 */ 3525 void 3526 bpdone(struct buf *bp, int elseit) 3527 { 3528 buf_cmd_t cmd; 3529 3530 KASSERT(BUF_LOCKINUSE(bp), ("bpdone: bp %p not busy", bp)); 3531 KASSERT(bp->b_cmd != BUF_CMD_DONE, 3532 ("bpdone: bp %p already done!", bp)); 3533 3534 /* 3535 * No more BIOs are left. All completion functions have been dealt 3536 * with, now we clean up the buffer. 3537 */ 3538 cmd = bp->b_cmd; 3539 bp->b_cmd = BUF_CMD_DONE; 3540 3541 /* 3542 * Only reads and writes are processed past this point. 3543 */ 3544 if (cmd != BUF_CMD_READ && cmd != BUF_CMD_WRITE) { 3545 if (cmd == BUF_CMD_FREEBLKS) 3546 bp->b_flags |= B_NOCACHE; 3547 if (elseit) 3548 brelse(bp); 3549 return; 3550 } 3551 3552 /* 3553 * A failed write must re-dirty the buffer unless B_INVAL 3554 * was set. 3555 * 3556 * A successful write must clear the dirty flag. This is done after 3557 * the write to ensure that the buffer remains on the vnode's dirty 3558 * list for filesystem interlocks / checks until the write is actually 3559 * complete. HAMMER2 is sensitive to this issue. 3560 * 3561 * Only applicable to normal buffers (with VPs). vinum buffers may 3562 * not have a vp. 3563 * 3564 * Must be done prior to calling buf_complete() as the callback might 3565 * re-dirty the buffer. 3566 */ 3567 if (cmd == BUF_CMD_WRITE) { 3568 if ((bp->b_flags & (B_ERROR | B_INVAL)) == B_ERROR) { 3569 bp->b_flags &= ~B_NOCACHE; 3570 if (bp->b_vp) 3571 bdirty(bp); 3572 } else { 3573 if (bp->b_vp) 3574 bundirty(bp); 3575 } 3576 } 3577 3578 /* 3579 * Warning: softupdates may re-dirty the buffer, and HAMMER can do 3580 * a lot worse. XXX - move this above the clearing of b_cmd 3581 */ 3582 if (LIST_FIRST(&bp->b_dep) != NULL) 3583 buf_complete(bp); 3584 3585 if (bp->b_flags & B_VMIO) { 3586 int i; 3587 vm_ooffset_t foff; 3588 vm_page_t m; 3589 vm_object_t obj; 3590 int iosize; 3591 struct vnode *vp = bp->b_vp; 3592 3593 obj = vp->v_object; 3594 3595 #if defined(VFS_BIO_DEBUG) 3596 if (vp->v_auxrefs == 0) 3597 panic("bpdone: zero vnode hold count"); 3598 if ((vp->v_flag & VOBJBUF) == 0) 3599 panic("bpdone: vnode is not setup for merged cache"); 3600 #endif 3601 3602 foff = bp->b_loffset; 3603 KASSERT(foff != NOOFFSET, ("bpdone: no buffer offset")); 3604 KASSERT(obj != NULL, ("bpdone: missing VM object")); 3605 3606 #if defined(VFS_BIO_DEBUG) 3607 if (obj->paging_in_progress < bp->b_xio.xio_npages) { 3608 kprintf("bpdone: paging in progress(%d) < " 3609 "bp->b_xio.xio_npages(%d)\n", 3610 obj->paging_in_progress, 3611 bp->b_xio.xio_npages); 3612 } 3613 #endif 3614 3615 /* 3616 * Set B_CACHE if the op was a normal read and no error 3617 * occured. B_CACHE is set for writes in the b*write() 3618 * routines. 3619 */ 3620 iosize = bp->b_bcount - bp->b_resid; 3621 if (cmd == BUF_CMD_READ && 3622 (bp->b_flags & (B_INVAL|B_NOCACHE|B_ERROR)) == 0) { 3623 bp->b_flags |= B_CACHE; 3624 } 3625 3626 vm_object_hold(obj); 3627 for (i = 0; i < bp->b_xio.xio_npages; i++) { 3628 int resid; 3629 int isbogus; 3630 3631 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 3632 if (resid > iosize) 3633 resid = iosize; 3634 3635 /* 3636 * cleanup bogus pages, restoring the originals. Since 3637 * the originals should still be wired, we don't have 3638 * to worry about interrupt/freeing races destroying 3639 * the VM object association. 3640 */ 3641 m = bp->b_xio.xio_pages[i]; 3642 if (m == bogus_page) { 3643 if ((bp->b_flags & B_HASBOGUS) == 0) 3644 panic("bpdone: bp %p corrupt bogus", bp); 3645 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3646 if (m == NULL) 3647 panic("bpdone: page disappeared"); 3648 bp->b_xio.xio_pages[i] = m; 3649 isbogus = 1; 3650 } else { 3651 isbogus = 0; 3652 } 3653 #if defined(VFS_BIO_DEBUG) 3654 if (OFF_TO_IDX(foff) != m->pindex) { 3655 kprintf("bpdone: foff(%lu)/m->pindex(%ld) " 3656 "mismatch\n", 3657 (unsigned long)foff, (long)m->pindex); 3658 } 3659 #endif 3660 3661 /* 3662 * In the write case, the valid and clean bits are 3663 * already changed correctly (see bdwrite()), so we 3664 * only need to do this here in the read case. 3665 */ 3666 vm_page_busy_wait(m, FALSE, "bpdpgw"); 3667 if (cmd == BUF_CMD_READ && isbogus == 0 && resid > 0) 3668 vfs_clean_one_page(bp, i, m); 3669 3670 /* 3671 * when debugging new filesystems or buffer I/O 3672 * methods, this is the most common error that pops 3673 * up. if you see this, you have not set the page 3674 * busy flag correctly!!! 3675 */ 3676 if ((m->busy_count & PBUSY_MASK) == 0) { 3677 kprintf("bpdone: page busy < 0, " 3678 "pindex: %d, foff: 0x(%x,%x), " 3679 "resid: %d, index: %d\n", 3680 (int) m->pindex, (int)(foff >> 32), 3681 (int) foff & 0xffffffff, resid, i); 3682 if (!vn_isdisk(vp, NULL)) 3683 kprintf(" iosize: %ld, loffset: %lld, " 3684 "flags: 0x%08x, npages: %d\n", 3685 bp->b_vp->v_mount->mnt_stat.f_iosize, 3686 (long long)bp->b_loffset, 3687 bp->b_flags, bp->b_xio.xio_npages); 3688 else 3689 kprintf(" VDEV, loffset: %lld, flags: 0x%08x, npages: %d\n", 3690 (long long)bp->b_loffset, 3691 bp->b_flags, bp->b_xio.xio_npages); 3692 kprintf(" valid: 0x%x, dirty: 0x%x, " 3693 "wired: %d\n", 3694 m->valid, m->dirty, 3695 m->wire_count); 3696 panic("bpdone: page busy < 0"); 3697 } 3698 vm_page_io_finish(m); 3699 vm_page_wakeup(m); 3700 vm_object_pip_wakeup(obj); 3701 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3702 iosize -= resid; 3703 } 3704 if (bp->b_flags & B_HASBOGUS) { 3705 pmap_qenter_noinval(trunc_page((vm_offset_t)bp->b_data), 3706 bp->b_xio.xio_pages, 3707 bp->b_xio.xio_npages); 3708 bp->b_flags &= ~B_HASBOGUS; 3709 bkvareset(bp); 3710 } 3711 vm_object_drop(obj); 3712 } 3713 3714 /* 3715 * Finish up by releasing the buffer. There are no more synchronous 3716 * or asynchronous completions, those were handled by bio_done 3717 * callbacks. 3718 */ 3719 if (elseit) { 3720 if (bp->b_flags & (B_NOCACHE|B_INVAL|B_ERROR|B_RELBUF)) 3721 brelse(bp); 3722 else 3723 bqrelse(bp); 3724 } 3725 } 3726 3727 /* 3728 * Normal biodone. 3729 */ 3730 void 3731 biodone(struct bio *bio) 3732 { 3733 struct buf *bp = bio->bio_buf; 3734 3735 runningbufwakeup(bp); 3736 3737 /* 3738 * Run up the chain of BIO's. Leave b_cmd intact for the duration. 3739 */ 3740 while (bio) { 3741 biodone_t *done_func; 3742 struct bio_track *track; 3743 3744 /* 3745 * BIO tracking. Most but not all BIOs are tracked. 3746 */ 3747 if ((track = bio->bio_track) != NULL) { 3748 bio_track_rel(track); 3749 bio->bio_track = NULL; 3750 } 3751 3752 /* 3753 * A bio_done function terminates the loop. The function 3754 * will be responsible for any further chaining and/or 3755 * buffer management. 3756 * 3757 * WARNING! The done function can deallocate the buffer! 3758 */ 3759 if ((done_func = bio->bio_done) != NULL) { 3760 bio->bio_done = NULL; 3761 done_func(bio); 3762 return; 3763 } 3764 bio = bio->bio_prev; 3765 } 3766 3767 /* 3768 * If we've run out of bio's do normal [a]synchronous completion. 3769 */ 3770 bpdone(bp, 1); 3771 } 3772 3773 /* 3774 * Synchronous biodone - this terminates a synchronous BIO. 3775 * 3776 * bpdone() is called with elseit=FALSE, leaving the buffer completed 3777 * but still locked. The caller must brelse() the buffer after waiting 3778 * for completion. 3779 */ 3780 void 3781 biodone_sync(struct bio *bio) 3782 { 3783 struct buf *bp = bio->bio_buf; 3784 int flags; 3785 int nflags; 3786 3787 KKASSERT(bio == &bp->b_bio1); 3788 bpdone(bp, 0); 3789 3790 for (;;) { 3791 flags = bio->bio_flags; 3792 nflags = (flags | BIO_DONE) & ~BIO_WANT; 3793 3794 if (atomic_cmpset_int(&bio->bio_flags, flags, nflags)) { 3795 if (flags & BIO_WANT) 3796 wakeup(bio); 3797 break; 3798 } 3799 } 3800 } 3801 3802 /* 3803 * vfs_unbusy_pages: 3804 * 3805 * This routine is called in lieu of iodone in the case of 3806 * incomplete I/O. This keeps the busy status for pages 3807 * consistant. 3808 */ 3809 void 3810 vfs_unbusy_pages(struct buf *bp) 3811 { 3812 int i; 3813 3814 runningbufwakeup(bp); 3815 3816 if (bp->b_flags & B_VMIO) { 3817 struct vnode *vp = bp->b_vp; 3818 vm_object_t obj; 3819 3820 obj = vp->v_object; 3821 vm_object_hold(obj); 3822 3823 for (i = 0; i < bp->b_xio.xio_npages; i++) { 3824 vm_page_t m = bp->b_xio.xio_pages[i]; 3825 3826 /* 3827 * When restoring bogus changes the original pages 3828 * should still be wired, so we are in no danger of 3829 * losing the object association and do not need 3830 * critical section protection particularly. 3831 */ 3832 if (m == bogus_page) { 3833 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_loffset) + i); 3834 if (!m) { 3835 panic("vfs_unbusy_pages: page missing"); 3836 } 3837 bp->b_xio.xio_pages[i] = m; 3838 } 3839 vm_page_busy_wait(m, FALSE, "bpdpgw"); 3840 vm_page_io_finish(m); 3841 vm_page_wakeup(m); 3842 vm_object_pip_wakeup(obj); 3843 } 3844 if (bp->b_flags & B_HASBOGUS) { 3845 pmap_qenter_noinval(trunc_page((vm_offset_t)bp->b_data), 3846 bp->b_xio.xio_pages, 3847 bp->b_xio.xio_npages); 3848 bp->b_flags &= ~B_HASBOGUS; 3849 bkvareset(bp); 3850 } 3851 vm_object_drop(obj); 3852 } 3853 } 3854 3855 /* 3856 * vfs_busy_pages: 3857 * 3858 * This routine is called before a device strategy routine. 3859 * It is used to tell the VM system that paging I/O is in 3860 * progress, and treat the pages associated with the buffer 3861 * almost as being PBUSY_LOCKED. Also the object 'paging_in_progress' 3862 * flag is handled to make sure that the object doesn't become 3863 * inconsistant. 3864 * 3865 * Since I/O has not been initiated yet, certain buffer flags 3866 * such as B_ERROR or B_INVAL may be in an inconsistant state 3867 * and should be ignored. 3868 */ 3869 void 3870 vfs_busy_pages(struct vnode *vp, struct buf *bp) 3871 { 3872 int i, bogus; 3873 struct lwp *lp = curthread->td_lwp; 3874 3875 /* 3876 * The buffer's I/O command must already be set. If reading, 3877 * B_CACHE must be 0 (double check against callers only doing 3878 * I/O when B_CACHE is 0). 3879 */ 3880 KKASSERT(bp->b_cmd != BUF_CMD_DONE); 3881 KKASSERT(bp->b_cmd == BUF_CMD_WRITE || (bp->b_flags & B_CACHE) == 0); 3882 3883 if (bp->b_flags & B_VMIO) { 3884 vm_object_t obj; 3885 3886 obj = vp->v_object; 3887 KASSERT(bp->b_loffset != NOOFFSET, 3888 ("vfs_busy_pages: no buffer offset")); 3889 3890 /* 3891 * Busy all the pages. We have to busy them all at once 3892 * to avoid deadlocks. 3893 */ 3894 retry: 3895 for (i = 0; i < bp->b_xio.xio_npages; i++) { 3896 vm_page_t m = bp->b_xio.xio_pages[i]; 3897 3898 if (vm_page_busy_try(m, FALSE)) { 3899 vm_page_sleep_busy(m, FALSE, "vbpage"); 3900 while (--i >= 0) 3901 vm_page_wakeup(bp->b_xio.xio_pages[i]); 3902 goto retry; 3903 } 3904 } 3905 3906 /* 3907 * Setup for I/O, soft-busy the page right now because 3908 * the next loop may block. 3909 */ 3910 for (i = 0; i < bp->b_xio.xio_npages; i++) { 3911 vm_page_t m = bp->b_xio.xio_pages[i]; 3912 3913 if ((bp->b_flags & B_CLUSTER) == 0) { 3914 vm_object_pip_add(obj, 1); 3915 vm_page_io_start(m); 3916 } 3917 } 3918 3919 /* 3920 * Adjust protections for I/O and do bogus-page mapping. 3921 * Assume that vm_page_protect() can block (it can block 3922 * if VM_PROT_NONE, don't take any chances regardless). 3923 * 3924 * In particular note that for writes we must incorporate 3925 * page dirtyness from the VM system into the buffer's 3926 * dirty range. 3927 * 3928 * For reads we theoretically must incorporate page dirtyness 3929 * from the VM system to determine if the page needs bogus 3930 * replacement, but we shortcut the test by simply checking 3931 * that all m->valid bits are set, indicating that the page 3932 * is fully valid and does not need to be re-read. For any 3933 * VM system dirtyness the page will also be fully valid 3934 * since it was mapped at one point. 3935 */ 3936 bogus = 0; 3937 for (i = 0; i < bp->b_xio.xio_npages; i++) { 3938 vm_page_t m = bp->b_xio.xio_pages[i]; 3939 3940 if (bp->b_cmd == BUF_CMD_WRITE) { 3941 /* 3942 * When readying a vnode-backed buffer for 3943 * a write we must zero-fill any invalid 3944 * portions of the backing VM pages, mark 3945 * it valid and clear related dirty bits. 3946 * 3947 * vfs_clean_one_page() incorporates any 3948 * VM dirtyness and updates the b_dirtyoff 3949 * range (after we've made the page RO). 3950 * 3951 * It is also expected that the pmap modified 3952 * bit has already been cleared by the 3953 * vm_page_protect(). We may not be able 3954 * to clear all dirty bits for a page if it 3955 * was also memory mapped (NFS). 3956 * 3957 * Finally be sure to unassign any swap-cache 3958 * backing store as it is now stale. 3959 */ 3960 vm_page_protect(m, VM_PROT_READ); 3961 vfs_clean_one_page(bp, i, m); 3962 swap_pager_unswapped(m); 3963 } else if (m->valid == VM_PAGE_BITS_ALL) { 3964 /* 3965 * When readying a vnode-backed buffer for 3966 * read we must replace any dirty pages with 3967 * a bogus page so dirty data is not destroyed 3968 * when filling gaps. 3969 * 3970 * To avoid testing whether the page is 3971 * dirty we instead test that the page was 3972 * at some point mapped (m->valid fully 3973 * valid) with the understanding that 3974 * this also covers the dirty case. 3975 */ 3976 bp->b_xio.xio_pages[i] = bogus_page; 3977 bp->b_flags |= B_HASBOGUS; 3978 bogus++; 3979 } else if (m->valid & m->dirty) { 3980 /* 3981 * This case should not occur as partial 3982 * dirtyment can only happen if the buffer 3983 * is B_CACHE, and this code is not entered 3984 * if the buffer is B_CACHE. 3985 */ 3986 kprintf("Warning: vfs_busy_pages - page not " 3987 "fully valid! loff=%jx bpf=%08x " 3988 "idx=%d val=%02x dir=%02x\n", 3989 (uintmax_t)bp->b_loffset, bp->b_flags, 3990 i, m->valid, m->dirty); 3991 vm_page_protect(m, VM_PROT_NONE); 3992 } else { 3993 /* 3994 * The page is not valid and can be made 3995 * part of the read. 3996 */ 3997 vm_page_protect(m, VM_PROT_NONE); 3998 } 3999 vm_page_wakeup(m); 4000 } 4001 if (bogus) { 4002 pmap_qenter_noinval(trunc_page((vm_offset_t)bp->b_data), 4003 bp->b_xio.xio_pages, 4004 bp->b_xio.xio_npages); 4005 bkvareset(bp); 4006 } 4007 } 4008 4009 /* 4010 * This is the easiest place to put the process accounting for the I/O 4011 * for now. 4012 */ 4013 if (lp != NULL) { 4014 if (bp->b_cmd == BUF_CMD_READ) 4015 lp->lwp_ru.ru_inblock++; 4016 else 4017 lp->lwp_ru.ru_oublock++; 4018 } 4019 } 4020 4021 /* 4022 * Tell the VM system that the pages associated with this buffer 4023 * are clean. This is used for delayed writes where the data is 4024 * going to go to disk eventually without additional VM intevention. 4025 * 4026 * NOTE: While we only really need to clean through to b_bcount, we 4027 * just go ahead and clean through to b_bufsize. 4028 */ 4029 static void 4030 vfs_clean_pages(struct buf *bp) 4031 { 4032 vm_page_t m; 4033 int i; 4034 4035 if ((bp->b_flags & B_VMIO) == 0) 4036 return; 4037 4038 KASSERT(bp->b_loffset != NOOFFSET, 4039 ("vfs_clean_pages: no buffer offset")); 4040 4041 for (i = 0; i < bp->b_xio.xio_npages; i++) { 4042 m = bp->b_xio.xio_pages[i]; 4043 vfs_clean_one_page(bp, i, m); 4044 } 4045 } 4046 4047 /* 4048 * vfs_clean_one_page: 4049 * 4050 * Set the valid bits and clear the dirty bits in a page within a 4051 * buffer. The range is restricted to the buffer's size and the 4052 * buffer's logical offset might index into the first page. 4053 * 4054 * The caller has busied or soft-busied the page and it is not mapped, 4055 * test and incorporate the dirty bits into b_dirtyoff/end before 4056 * clearing them. Note that we need to clear the pmap modified bits 4057 * after determining the the page was dirty, vm_page_set_validclean() 4058 * does not do it for us. 4059 * 4060 * This routine is typically called after a read completes (dirty should 4061 * be zero in that case as we are not called on bogus-replace pages), 4062 * or before a write is initiated. 4063 */ 4064 static void 4065 vfs_clean_one_page(struct buf *bp, int pageno, vm_page_t m) 4066 { 4067 int bcount; 4068 int xoff; 4069 int soff; 4070 int eoff; 4071 4072 /* 4073 * Calculate offset range within the page but relative to buffer's 4074 * loffset. loffset might be offset into the first page. 4075 */ 4076 xoff = (int)bp->b_loffset & PAGE_MASK; /* loffset offset into pg 0 */ 4077 bcount = bp->b_bcount + xoff; /* offset adjusted */ 4078 4079 if (pageno == 0) { 4080 soff = xoff; 4081 eoff = PAGE_SIZE; 4082 } else { 4083 soff = (pageno << PAGE_SHIFT); 4084 eoff = soff + PAGE_SIZE; 4085 } 4086 if (eoff > bcount) 4087 eoff = bcount; 4088 if (soff >= eoff) 4089 return; 4090 4091 /* 4092 * Test dirty bits and adjust b_dirtyoff/end. 4093 * 4094 * If dirty pages are incorporated into the bp any prior 4095 * B_NEEDCOMMIT state (NFS) must be cleared because the 4096 * caller has not taken into account the new dirty data. 4097 * 4098 * If the page was memory mapped the dirty bits might go beyond the 4099 * end of the buffer, but we can't really make the assumption that 4100 * a file EOF straddles the buffer (even though this is the case for 4101 * NFS if B_NEEDCOMMIT is also set). So for the purposes of clearing 4102 * B_NEEDCOMMIT we only test the dirty bits covered by the buffer. 4103 * This also saves some console spam. 4104 * 4105 * When clearing B_NEEDCOMMIT we must also clear B_CLUSTEROK, 4106 * NFS can handle huge commits but not huge writes. 4107 */ 4108 vm_page_test_dirty(m); 4109 if (m->dirty) { 4110 if ((bp->b_flags & B_NEEDCOMMIT) && 4111 (m->dirty & vm_page_bits(soff & PAGE_MASK, eoff - soff))) { 4112 if (debug_commit) 4113 kprintf("Warning: vfs_clean_one_page: bp %p " 4114 "loff=%jx,%d flgs=%08x clr B_NEEDCOMMIT" 4115 " cmd %d vd %02x/%02x x/s/e %d %d %d " 4116 "doff/end %d %d\n", 4117 bp, (uintmax_t)bp->b_loffset, bp->b_bcount, 4118 bp->b_flags, bp->b_cmd, 4119 m->valid, m->dirty, xoff, soff, eoff, 4120 bp->b_dirtyoff, bp->b_dirtyend); 4121 bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK); 4122 if (debug_commit) 4123 print_backtrace(-1); 4124 } 4125 /* 4126 * Only clear the pmap modified bits if ALL the dirty bits 4127 * are set, otherwise the system might mis-clear portions 4128 * of a page. 4129 */ 4130 if (m->dirty == VM_PAGE_BITS_ALL && 4131 (bp->b_flags & B_NEEDCOMMIT) == 0) { 4132 pmap_clear_modify(m); 4133 } 4134 if (bp->b_dirtyoff > soff - xoff) 4135 bp->b_dirtyoff = soff - xoff; 4136 if (bp->b_dirtyend < eoff - xoff) 4137 bp->b_dirtyend = eoff - xoff; 4138 } 4139 4140 /* 4141 * Set related valid bits, clear related dirty bits. 4142 * Does not mess with the pmap modified bit. 4143 * 4144 * WARNING! We cannot just clear all of m->dirty here as the 4145 * buffer cache buffers may use a DEV_BSIZE'd aligned 4146 * block size, or have an odd size (e.g. NFS at file EOF). 4147 * The putpages code can clear m->dirty to 0. 4148 * 4149 * If a VOP_WRITE generates a buffer cache buffer which 4150 * covers the same space as mapped writable pages the 4151 * buffer flush might not be able to clear all the dirty 4152 * bits and still require a putpages from the VM system 4153 * to finish it off. 4154 * 4155 * WARNING! vm_page_set_validclean() currently assumes vm_token 4156 * is held. The page might not be busied (bdwrite() case). 4157 * XXX remove this comment once we've validated that this 4158 * is no longer an issue. 4159 */ 4160 vm_page_set_validclean(m, soff & PAGE_MASK, eoff - soff); 4161 } 4162 4163 #if 0 4164 /* 4165 * Similar to vfs_clean_one_page() but sets the bits to valid and dirty. 4166 * The page data is assumed to be valid (there is no zeroing here). 4167 */ 4168 static void 4169 vfs_dirty_one_page(struct buf *bp, int pageno, vm_page_t m) 4170 { 4171 int bcount; 4172 int xoff; 4173 int soff; 4174 int eoff; 4175 4176 /* 4177 * Calculate offset range within the page but relative to buffer's 4178 * loffset. loffset might be offset into the first page. 4179 */ 4180 xoff = (int)bp->b_loffset & PAGE_MASK; /* loffset offset into pg 0 */ 4181 bcount = bp->b_bcount + xoff; /* offset adjusted */ 4182 4183 if (pageno == 0) { 4184 soff = xoff; 4185 eoff = PAGE_SIZE; 4186 } else { 4187 soff = (pageno << PAGE_SHIFT); 4188 eoff = soff + PAGE_SIZE; 4189 } 4190 if (eoff > bcount) 4191 eoff = bcount; 4192 if (soff >= eoff) 4193 return; 4194 vm_page_set_validdirty(m, soff & PAGE_MASK, eoff - soff); 4195 } 4196 #endif 4197 4198 /* 4199 * vfs_bio_clrbuf: 4200 * 4201 * Clear a buffer. This routine essentially fakes an I/O, so we need 4202 * to clear B_ERROR and B_INVAL. 4203 * 4204 * Note that while we only theoretically need to clear through b_bcount, 4205 * we go ahead and clear through b_bufsize. 4206 */ 4207 void 4208 vfs_bio_clrbuf(struct buf *bp) 4209 { 4210 int i, mask = 0; 4211 caddr_t sa, ea; 4212 KKASSERT(bp->b_flags & B_VMIO); 4213 4214 bp->b_flags &= ~(B_INVAL | B_EINTR | B_ERROR); 4215 bkvasync(bp); 4216 4217 if ((bp->b_xio.xio_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 4218 (bp->b_loffset & PAGE_MASK) == 0) { 4219 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 4220 if ((bp->b_xio.xio_pages[0]->valid & mask) == mask) { 4221 bp->b_resid = 0; 4222 return; 4223 } 4224 if ((bp->b_xio.xio_pages[0]->valid & mask) == 0) { 4225 bzero(bp->b_data, bp->b_bufsize); 4226 bp->b_xio.xio_pages[0]->valid |= mask; 4227 bp->b_resid = 0; 4228 return; 4229 } 4230 } 4231 sa = bp->b_data; 4232 for(i = 0; i < bp->b_xio.xio_npages; i++, sa=ea) { 4233 int j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; 4234 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); 4235 ea = (caddr_t)(vm_offset_t)ulmin( 4236 (u_long)(vm_offset_t)ea, 4237 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); 4238 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 4239 if ((bp->b_xio.xio_pages[i]->valid & mask) == mask) 4240 continue; 4241 if ((bp->b_xio.xio_pages[i]->valid & mask) == 0) { 4242 bzero(sa, ea - sa); 4243 } else { 4244 for (; sa < ea; sa += DEV_BSIZE, j++) { 4245 if ((bp->b_xio.xio_pages[i]->valid & 4246 (1<<j)) == 0) { 4247 bzero(sa, DEV_BSIZE); 4248 } 4249 } 4250 } 4251 bp->b_xio.xio_pages[i]->valid |= mask; 4252 } 4253 bp->b_resid = 0; 4254 } 4255 4256 /* 4257 * Allocate a page for a buffer cache buffer. 4258 * 4259 * If NULL is returned the caller is expected to retry (typically check if 4260 * the page already exists on retry before trying to allocate one). 4261 * 4262 * NOTE! Low-memory handling is dealt with in b[q]relse(), not here. This 4263 * function will use the system reserve with the hope that the page 4264 * allocations can be returned to PQ_CACHE/PQ_FREE when the caller 4265 * is done with the buffer. 4266 * 4267 * NOTE! However, TMPFS is a special case because flushing a dirty buffer 4268 * to TMPFS doesn't clean the page. For TMPFS, only the pagedaemon 4269 * is capable of retiring pages (to swap). For TMPFS we don't dig 4270 * into the system reserve because doing so could stall out pretty 4271 * much every process running on the system. 4272 */ 4273 static 4274 vm_page_t 4275 bio_page_alloc(struct buf *bp, vm_object_t obj, vm_pindex_t pg, int deficit) 4276 { 4277 int vmflags = VM_ALLOC_NORMAL | VM_ALLOC_NULL_OK; 4278 vm_page_t p; 4279 4280 ASSERT_LWKT_TOKEN_HELD(vm_object_token(obj)); 4281 4282 /* 4283 * Try a normal allocation first. 4284 */ 4285 p = vm_page_alloc(obj, pg, vmflags); 4286 if (p) 4287 return(p); 4288 if (vm_page_lookup(obj, pg)) 4289 return(NULL); 4290 vm_pageout_deficit += deficit; 4291 4292 /* 4293 * Try again, digging into the system reserve. 4294 * 4295 * Trying to recover pages from the buffer cache here can deadlock 4296 * against other threads trying to busy underlying pages so we 4297 * depend on the code in brelse() and bqrelse() to free/cache the 4298 * underlying buffer cache pages when memory is low. 4299 */ 4300 if (curthread->td_flags & TDF_SYSTHREAD) 4301 vmflags |= VM_ALLOC_SYSTEM | VM_ALLOC_INTERRUPT; 4302 else if (bp->b_vp && bp->b_vp->v_tag == VT_TMPFS) 4303 vmflags |= 0; 4304 else 4305 vmflags |= VM_ALLOC_SYSTEM; 4306 4307 /*recoverbufpages();*/ 4308 p = vm_page_alloc(obj, pg, vmflags); 4309 if (p) 4310 return(p); 4311 if (vm_page_lookup(obj, pg)) 4312 return(NULL); 4313 4314 /* 4315 * Wait for memory to free up and try again 4316 */ 4317 if (vm_page_count_severe()) 4318 ++lowmempgallocs; 4319 vm_wait(hz / 20 + 1); 4320 4321 p = vm_page_alloc(obj, pg, vmflags); 4322 if (p) 4323 return(p); 4324 if (vm_page_lookup(obj, pg)) 4325 return(NULL); 4326 4327 /* 4328 * Ok, now we are really in trouble. 4329 */ 4330 if (bootverbose) { 4331 static struct krate biokrate = { .freq = 1 }; 4332 krateprintf(&biokrate, 4333 "Warning: bio_page_alloc: memory exhausted " 4334 "during buffer cache page allocation from %s\n", 4335 curthread->td_comm); 4336 } 4337 if (curthread->td_flags & TDF_SYSTHREAD) 4338 vm_wait(hz / 20 + 1); 4339 else 4340 vm_wait(hz / 2 + 1); 4341 return (NULL); 4342 } 4343 4344 /* 4345 * The buffer's mapping has changed. Adjust the buffer's memory 4346 * synchronization. The caller is the exclusive holder of the buffer 4347 * and has set or cleared B_KVABIO according to preference. 4348 * 4349 * WARNING! If the caller is using B_KVABIO mode, this function will 4350 * not map the data to the current cpu. The caller must also 4351 * call bkvasync(bp). 4352 */ 4353 void 4354 bkvareset(struct buf *bp) 4355 { 4356 if (bp->b_flags & B_KVABIO) { 4357 CPUMASK_ASSZERO(bp->b_cpumask); 4358 } else { 4359 CPUMASK_ORMASK(bp->b_cpumask, smp_active_mask); 4360 smp_invltlb(); 4361 cpu_invltlb(); 4362 } 4363 } 4364 4365 /* 4366 * The buffer will be used by the caller on the caller's cpu, synchronize 4367 * its data to the current cpu. Caller must control the buffer by holding 4368 * its lock, but calling cpu does not necessarily have to be the owner of 4369 * the lock (i.e. HAMMER2's concurrent I/O accessors). 4370 * 4371 * If B_KVABIO is not set, the buffer is already fully synchronized. 4372 */ 4373 void 4374 bkvasync(struct buf *bp) 4375 { 4376 int cpuid = mycpu->gd_cpuid; 4377 char *bdata; 4378 4379 if ((bp->b_flags & B_KVABIO) && 4380 CPUMASK_TESTBIT(bp->b_cpumask, cpuid) == 0) { 4381 bdata = bp->b_data; 4382 while (bdata < bp->b_data + bp->b_bufsize) { 4383 cpu_invlpg(bdata); 4384 bdata += PAGE_SIZE - 4385 ((intptr_t)bdata & PAGE_MASK); 4386 } 4387 ATOMIC_CPUMASK_ORBIT(bp->b_cpumask, cpuid); 4388 } 4389 } 4390 4391 /* 4392 * The buffer will be used by a subsystem that does not understand 4393 * the KVABIO API. Make sure its data is synchronized to all cpus. 4394 * 4395 * If B_KVABIO is not set, the buffer is already fully synchronized. 4396 * 4397 * NOTE! This is the only safe way to clear B_KVABIO on a buffer. 4398 */ 4399 void 4400 bkvasync_all(struct buf *bp) 4401 { 4402 if (debug_kvabio > 0) { 4403 --debug_kvabio; 4404 print_backtrace(10); 4405 } 4406 4407 if ((bp->b_flags & B_KVABIO) && 4408 CPUMASK_CMPMASKNEQ(bp->b_cpumask, smp_active_mask)) { 4409 smp_invltlb(); 4410 cpu_invltlb(); 4411 ATOMIC_CPUMASK_ORMASK(bp->b_cpumask, smp_active_mask); 4412 } 4413 bp->b_flags &= ~B_KVABIO; 4414 } 4415 4416 /* 4417 * Scan all buffers in the system and issue the callback. 4418 */ 4419 int 4420 scan_all_buffers(int (*callback)(struct buf *, void *), void *info) 4421 { 4422 int count = 0; 4423 int error; 4424 long n; 4425 4426 for (n = 0; n < nbuf; ++n) { 4427 if ((error = callback(&buf[n], info)) < 0) { 4428 count = error; 4429 break; 4430 } 4431 count += error; 4432 } 4433 return (count); 4434 } 4435 4436 /* 4437 * nestiobuf_iodone: biodone callback for nested buffers and propagate 4438 * completion to the master buffer. 4439 */ 4440 static void 4441 nestiobuf_iodone(struct bio *bio) 4442 { 4443 struct bio *mbio; 4444 struct buf *mbp, *bp; 4445 struct devstat *stats; 4446 int error; 4447 int donebytes; 4448 4449 bp = bio->bio_buf; 4450 mbio = bio->bio_caller_info1.ptr; 4451 stats = bio->bio_caller_info2.ptr; 4452 mbp = mbio->bio_buf; 4453 4454 KKASSERT(bp->b_bcount <= bp->b_bufsize); 4455 KKASSERT(mbp != bp); 4456 4457 error = bp->b_error; 4458 if (bp->b_error == 0 && 4459 (bp->b_bcount < bp->b_bufsize || bp->b_resid > 0)) { 4460 /* 4461 * Not all got transfered, raise an error. We have no way to 4462 * propagate these conditions to mbp. 4463 */ 4464 error = EIO; 4465 } 4466 4467 donebytes = bp->b_bufsize; 4468 4469 relpbuf(bp, NULL); 4470 4471 nestiobuf_done(mbio, donebytes, error, stats); 4472 } 4473 4474 void 4475 nestiobuf_done(struct bio *mbio, int donebytes, int error, struct devstat *stats) 4476 { 4477 struct buf *mbp; 4478 4479 mbp = mbio->bio_buf; 4480 4481 KKASSERT((int)(intptr_t)mbio->bio_driver_info > 0); 4482 4483 /* 4484 * If an error occured, propagate it to the master buffer. 4485 * 4486 * Several biodone()s may wind up running concurrently so 4487 * use an atomic op to adjust b_flags. 4488 */ 4489 if (error) { 4490 mbp->b_error = error; 4491 atomic_set_int(&mbp->b_flags, B_ERROR); 4492 } 4493 4494 /* 4495 * Decrement the operations in progress counter and terminate the 4496 * I/O if this was the last bit. 4497 */ 4498 if (atomic_fetchadd_int((int *)&mbio->bio_driver_info, -1) == 1) { 4499 mbp->b_resid = 0; 4500 if (stats) 4501 devstat_end_transaction_buf(stats, mbp); 4502 biodone(mbio); 4503 } 4504 } 4505 4506 /* 4507 * Initialize a nestiobuf for use. Set an initial count of 1 to prevent 4508 * the mbio from being biodone()'d while we are still adding sub-bios to 4509 * it. 4510 */ 4511 void 4512 nestiobuf_init(struct bio *bio) 4513 { 4514 bio->bio_driver_info = (void *)1; 4515 } 4516 4517 /* 4518 * The BIOs added to the nestedio have already been started, remove the 4519 * count that placeheld our mbio and biodone() it if the count would 4520 * transition to 0. 4521 */ 4522 void 4523 nestiobuf_start(struct bio *mbio) 4524 { 4525 struct buf *mbp = mbio->bio_buf; 4526 4527 /* 4528 * Decrement the operations in progress counter and terminate the 4529 * I/O if this was the last bit. 4530 */ 4531 if (atomic_fetchadd_int((int *)&mbio->bio_driver_info, -1) == 1) { 4532 if (mbp->b_flags & B_ERROR) 4533 mbp->b_resid = mbp->b_bcount; 4534 else 4535 mbp->b_resid = 0; 4536 biodone(mbio); 4537 } 4538 } 4539 4540 /* 4541 * Set an intermediate error prior to calling nestiobuf_start() 4542 */ 4543 void 4544 nestiobuf_error(struct bio *mbio, int error) 4545 { 4546 struct buf *mbp = mbio->bio_buf; 4547 4548 if (error) { 4549 mbp->b_error = error; 4550 atomic_set_int(&mbp->b_flags, B_ERROR); 4551 } 4552 } 4553 4554 /* 4555 * nestiobuf_add: setup a "nested" buffer. 4556 * 4557 * => 'mbp' is a "master" buffer which is being divided into sub pieces. 4558 * => 'bp' should be a buffer allocated by getiobuf. 4559 * => 'offset' is a byte offset in the master buffer. 4560 * => 'size' is a size in bytes of this nested buffer. 4561 */ 4562 void 4563 nestiobuf_add(struct bio *mbio, struct buf *bp, int offset, size_t size, struct devstat *stats) 4564 { 4565 struct buf *mbp = mbio->bio_buf; 4566 struct vnode *vp = mbp->b_vp; 4567 4568 KKASSERT(mbp->b_bcount >= offset + size); 4569 4570 atomic_add_int((int *)&mbio->bio_driver_info, 1); 4571 4572 /* kernel needs to own the lock for it to be released in biodone */ 4573 BUF_KERNPROC(bp); 4574 bp->b_vp = vp; 4575 bp->b_cmd = mbp->b_cmd; 4576 bp->b_bio1.bio_done = nestiobuf_iodone; 4577 bp->b_data = (char *)mbp->b_data + offset; 4578 bp->b_resid = bp->b_bcount = size; 4579 bp->b_bufsize = bp->b_bcount; 4580 4581 bp->b_bio1.bio_track = NULL; 4582 bp->b_bio1.bio_caller_info1.ptr = mbio; 4583 bp->b_bio1.bio_caller_info2.ptr = stats; 4584 } 4585 4586 #ifdef DDB 4587 4588 DB_SHOW_COMMAND(buffer, db_show_buffer) 4589 { 4590 /* get args */ 4591 struct buf *bp = (struct buf *)addr; 4592 4593 if (!have_addr) { 4594 db_printf("usage: show buffer <addr>\n"); 4595 return; 4596 } 4597 4598 db_printf("b_flags = 0x%pb%i\n", PRINT_BUF_FLAGS, bp->b_flags); 4599 db_printf("b_cmd = %d\n", bp->b_cmd); 4600 db_printf("b_error = %d, b_bufsize = %d, b_bcount = %d, " 4601 "b_resid = %d\n, b_data = %p, " 4602 "bio_offset(disk) = %lld, bio_offset(phys) = %lld\n", 4603 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 4604 bp->b_data, 4605 (long long)bp->b_bio2.bio_offset, 4606 (long long)(bp->b_bio2.bio_next ? 4607 bp->b_bio2.bio_next->bio_offset : (off_t)-1)); 4608 if (bp->b_xio.xio_npages) { 4609 int i; 4610 db_printf("b_xio.xio_npages = %d, pages(OBJ, IDX, PA): ", 4611 bp->b_xio.xio_npages); 4612 for (i = 0; i < bp->b_xio.xio_npages; i++) { 4613 vm_page_t m; 4614 m = bp->b_xio.xio_pages[i]; 4615 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 4616 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 4617 if ((i + 1) < bp->b_xio.xio_npages) 4618 db_printf(","); 4619 } 4620 db_printf("\n"); 4621 } 4622 } 4623 #endif /* DDB */ 4624