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 * $DragonFly: src/sys/kern/vfs_bio.c,v 1.115 2008/08/13 11:02:31 swildner Exp $ 16 */ 17 18 /* 19 * this file contains a new buffer I/O scheme implementing a coherent 20 * VM object and buffer cache scheme. Pains have been taken to make 21 * sure that the performance degradation associated with schemes such 22 * as this is not realized. 23 * 24 * Author: John S. Dyson 25 * Significant help during the development and debugging phases 26 * had been provided by David Greenman, also of the FreeBSD core team. 27 * 28 * see man buf(9) for more info. 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/eventhandler.h> 36 #include <sys/lock.h> 37 #include <sys/malloc.h> 38 #include <sys/mount.h> 39 #include <sys/kernel.h> 40 #include <sys/kthread.h> 41 #include <sys/proc.h> 42 #include <sys/reboot.h> 43 #include <sys/resourcevar.h> 44 #include <sys/sysctl.h> 45 #include <sys/vmmeter.h> 46 #include <sys/vnode.h> 47 #include <sys/proc.h> 48 #include <vm/vm.h> 49 #include <vm/vm_param.h> 50 #include <vm/vm_kern.h> 51 #include <vm/vm_pageout.h> 52 #include <vm/vm_page.h> 53 #include <vm/vm_object.h> 54 #include <vm/vm_extern.h> 55 #include <vm/vm_map.h> 56 #include <vm/vm_pager.h> 57 #include <vm/swap_pager.h> 58 59 #include <sys/buf2.h> 60 #include <sys/thread2.h> 61 #include <sys/spinlock2.h> 62 #include <sys/mplock2.h> 63 #include <vm/vm_page2.h> 64 65 #include "opt_ddb.h" 66 #ifdef DDB 67 #include <ddb/ddb.h> 68 #endif 69 70 /* 71 * Buffer queues. 72 */ 73 enum bufq_type { 74 BQUEUE_NONE, /* not on any queue */ 75 BQUEUE_LOCKED, /* locked buffers */ 76 BQUEUE_CLEAN, /* non-B_DELWRI buffers */ 77 BQUEUE_DIRTY, /* B_DELWRI buffers */ 78 BQUEUE_DIRTY_HW, /* B_DELWRI buffers - heavy weight */ 79 BQUEUE_EMPTYKVA, /* empty buffer headers with KVA assignment */ 80 BQUEUE_EMPTY, /* empty buffer headers */ 81 82 BUFFER_QUEUES /* number of buffer queues */ 83 }; 84 85 typedef enum bufq_type bufq_type_t; 86 87 #define BD_WAKE_SIZE 16384 88 #define BD_WAKE_MASK (BD_WAKE_SIZE - 1) 89 90 TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES]; 91 struct spinlock bufspin = SPINLOCK_INITIALIZER(&bufspin); 92 93 static MALLOC_DEFINE(M_BIOBUF, "BIO buffer", "BIO buffer"); 94 95 struct buf *buf; /* buffer header pool */ 96 97 static void vfs_clean_pages(struct buf *bp); 98 static void vfs_clean_one_page(struct buf *bp, int pageno, vm_page_t m); 99 static void vfs_dirty_one_page(struct buf *bp, int pageno, vm_page_t m); 100 static void vfs_vmio_release(struct buf *bp); 101 static int flushbufqueues(bufq_type_t q); 102 static vm_page_t bio_page_alloc(vm_object_t obj, vm_pindex_t pg, int deficit); 103 104 static void bd_signal(int totalspace); 105 static void buf_daemon(void); 106 static void buf_daemon_hw(void); 107 108 /* 109 * bogus page -- for I/O to/from partially complete buffers 110 * this is a temporary solution to the problem, but it is not 111 * really that bad. it would be better to split the buffer 112 * for input in the case of buffers partially already in memory, 113 * but the code is intricate enough already. 114 */ 115 vm_page_t bogus_page; 116 117 /* 118 * These are all static, but make the ones we export globals so we do 119 * not need to use compiler magic. 120 */ 121 int bufspace, maxbufspace, 122 bufmallocspace, maxbufmallocspace, lobufspace, hibufspace; 123 static int bufreusecnt, bufdefragcnt, buffreekvacnt; 124 static int lorunningspace, hirunningspace, runningbufreq; 125 int dirtybufspace, dirtybufspacehw, lodirtybufspace, hidirtybufspace; 126 int dirtybufcount, dirtybufcounthw; 127 int runningbufspace, runningbufcount; 128 static int getnewbufcalls; 129 static int getnewbufrestarts; 130 static int recoverbufcalls; 131 static int needsbuffer; /* locked by needsbuffer_spin */ 132 static int bd_request; /* locked by needsbuffer_spin */ 133 static int bd_request_hw; /* locked by needsbuffer_spin */ 134 static u_int bd_wake_ary[BD_WAKE_SIZE]; 135 static u_int bd_wake_index; 136 static u_int vm_cycle_point = ACT_INIT + ACT_ADVANCE * 6; 137 static struct spinlock needsbuffer_spin; 138 static int debug_commit; 139 140 static struct thread *bufdaemon_td; 141 static struct thread *bufdaemonhw_td; 142 143 144 /* 145 * Sysctls for operational control of the buffer cache. 146 */ 147 SYSCTL_INT(_vfs, OID_AUTO, lodirtybufspace, CTLFLAG_RW, &lodirtybufspace, 0, 148 "Number of dirty buffers to flush before bufdaemon becomes inactive"); 149 SYSCTL_INT(_vfs, OID_AUTO, hidirtybufspace, CTLFLAG_RW, &hidirtybufspace, 0, 150 "High watermark used to trigger explicit flushing of dirty buffers"); 151 SYSCTL_INT(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0, 152 "Minimum amount of buffer space required for active I/O"); 153 SYSCTL_INT(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0, 154 "Maximum amount of buffer space to usable for active I/O"); 155 SYSCTL_UINT(_vfs, OID_AUTO, vm_cycle_point, CTLFLAG_RW, &vm_cycle_point, 0, 156 "Recycle pages to active or inactive queue transition pt 0-64"); 157 /* 158 * Sysctls determining current state of the buffer cache. 159 */ 160 SYSCTL_INT(_vfs, OID_AUTO, nbuf, CTLFLAG_RD, &nbuf, 0, 161 "Total number of buffers in buffer cache"); 162 SYSCTL_INT(_vfs, OID_AUTO, dirtybufspace, CTLFLAG_RD, &dirtybufspace, 0, 163 "Pending bytes of dirty buffers (all)"); 164 SYSCTL_INT(_vfs, OID_AUTO, dirtybufspacehw, CTLFLAG_RD, &dirtybufspacehw, 0, 165 "Pending bytes of dirty buffers (heavy weight)"); 166 SYSCTL_INT(_vfs, OID_AUTO, dirtybufcount, CTLFLAG_RD, &dirtybufcount, 0, 167 "Pending number of dirty buffers"); 168 SYSCTL_INT(_vfs, OID_AUTO, dirtybufcounthw, CTLFLAG_RD, &dirtybufcounthw, 0, 169 "Pending number of dirty buffers (heavy weight)"); 170 SYSCTL_INT(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 171 "I/O bytes currently in progress due to asynchronous writes"); 172 SYSCTL_INT(_vfs, OID_AUTO, runningbufcount, CTLFLAG_RD, &runningbufcount, 0, 173 "I/O buffers currently in progress due to asynchronous writes"); 174 SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0, 175 "Hard limit on maximum amount of memory usable for buffer space"); 176 SYSCTL_INT(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0, 177 "Soft limit on maximum amount of memory usable for buffer space"); 178 SYSCTL_INT(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0, 179 "Minimum amount of memory to reserve for system buffer space"); 180 SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, 181 "Amount of memory available for buffers"); 182 SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RD, &maxbufmallocspace, 183 0, "Maximum amount of memory reserved for buffers using malloc"); 184 SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 185 "Amount of memory left for buffers using malloc-scheme"); 186 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RD, &getnewbufcalls, 0, 187 "New buffer header acquisition requests"); 188 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RD, &getnewbufrestarts, 189 0, "New buffer header acquisition restarts"); 190 SYSCTL_INT(_vfs, OID_AUTO, recoverbufcalls, CTLFLAG_RD, &recoverbufcalls, 0, 191 "Recover VM space in an emergency"); 192 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RD, &bufdefragcnt, 0, 193 "Buffer acquisition restarts due to fragmented buffer map"); 194 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RD, &buffreekvacnt, 0, 195 "Amount of time KVA space was deallocated in an arbitrary buffer"); 196 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RD, &bufreusecnt, 0, 197 "Amount of time buffer re-use operations were successful"); 198 SYSCTL_INT(_vfs, OID_AUTO, debug_commit, CTLFLAG_RW, &debug_commit, 0, ""); 199 SYSCTL_INT(_debug_sizeof, OID_AUTO, buf, CTLFLAG_RD, 0, sizeof(struct buf), 200 "sizeof(struct buf)"); 201 202 char *buf_wmesg = BUF_WMESG; 203 204 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 205 #define VFS_BIO_NEED_UNUSED02 0x02 206 #define VFS_BIO_NEED_UNUSED04 0x04 207 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 208 209 /* 210 * bufspacewakeup: 211 * 212 * Called when buffer space is potentially available for recovery. 213 * getnewbuf() will block on this flag when it is unable to free 214 * sufficient buffer space. Buffer space becomes recoverable when 215 * bp's get placed back in the queues. 216 */ 217 218 static __inline void 219 bufspacewakeup(void) 220 { 221 /* 222 * If someone is waiting for BUF space, wake them up. Even 223 * though we haven't freed the kva space yet, the waiting 224 * process will be able to now. 225 */ 226 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) { 227 spin_lock_wr(&needsbuffer_spin); 228 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE; 229 spin_unlock_wr(&needsbuffer_spin); 230 wakeup(&needsbuffer); 231 } 232 } 233 234 /* 235 * runningbufwakeup: 236 * 237 * Accounting for I/O in progress. 238 * 239 */ 240 static __inline void 241 runningbufwakeup(struct buf *bp) 242 { 243 int totalspace; 244 int limit; 245 246 if ((totalspace = bp->b_runningbufspace) != 0) { 247 atomic_subtract_int(&runningbufspace, totalspace); 248 atomic_subtract_int(&runningbufcount, 1); 249 bp->b_runningbufspace = 0; 250 251 /* 252 * see waitrunningbufspace() for limit test. 253 */ 254 limit = hirunningspace * 2 / 3; 255 if (runningbufreq && runningbufspace <= limit) { 256 runningbufreq = 0; 257 wakeup(&runningbufreq); 258 } 259 bd_signal(totalspace); 260 } 261 } 262 263 /* 264 * bufcountwakeup: 265 * 266 * Called when a buffer has been added to one of the free queues to 267 * account for the buffer and to wakeup anyone waiting for free buffers. 268 * This typically occurs when large amounts of metadata are being handled 269 * by the buffer cache ( else buffer space runs out first, usually ). 270 * 271 * MPSAFE 272 */ 273 static __inline void 274 bufcountwakeup(void) 275 { 276 if (needsbuffer) { 277 spin_lock_wr(&needsbuffer_spin); 278 needsbuffer &= ~VFS_BIO_NEED_ANY; 279 spin_unlock_wr(&needsbuffer_spin); 280 wakeup(&needsbuffer); 281 } 282 } 283 284 /* 285 * waitrunningbufspace() 286 * 287 * Wait for the amount of running I/O to drop to hirunningspace * 2 / 3. 288 * This is the point where write bursting stops so we don't want to wait 289 * for the running amount to drop below it (at least if we still want bioq 290 * to burst writes). 291 * 292 * The caller may be using this function to block in a tight loop, we 293 * must block while runningbufspace is greater then or equal to 294 * hirunningspace * 2 / 3. 295 * 296 * And even with that it may not be enough, due to the presence of 297 * B_LOCKED dirty buffers, so also wait for at least one running buffer 298 * to complete. 299 */ 300 static __inline void 301 waitrunningbufspace(void) 302 { 303 int limit = hirunningspace * 2 / 3; 304 305 crit_enter(); 306 if (runningbufspace > limit) { 307 while (runningbufspace > limit) { 308 ++runningbufreq; 309 tsleep(&runningbufreq, 0, "wdrn1", 0); 310 } 311 } else if (runningbufspace) { 312 ++runningbufreq; 313 tsleep(&runningbufreq, 0, "wdrn2", 1); 314 } 315 crit_exit(); 316 } 317 318 /* 319 * buf_dirty_count_severe: 320 * 321 * Return true if we have too many dirty buffers. 322 */ 323 int 324 buf_dirty_count_severe(void) 325 { 326 return (runningbufspace + dirtybufspace >= hidirtybufspace || 327 dirtybufcount >= nbuf / 2); 328 } 329 330 /* 331 * Return true if the amount of running I/O is severe and BIOQ should 332 * start bursting. 333 */ 334 int 335 buf_runningbufspace_severe(void) 336 { 337 return (runningbufspace >= hirunningspace * 2 / 3); 338 } 339 340 /* 341 * vfs_buf_test_cache: 342 * 343 * Called when a buffer is extended. This function clears the B_CACHE 344 * bit if the newly extended portion of the buffer does not contain 345 * valid data. 346 * 347 * NOTE! Dirty VM pages are not processed into dirty (B_DELWRI) buffer 348 * cache buffers. The VM pages remain dirty, as someone had mmap()'d 349 * them while a clean buffer was present. 350 */ 351 static __inline__ 352 void 353 vfs_buf_test_cache(struct buf *bp, 354 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 355 vm_page_t m) 356 { 357 if (bp->b_flags & B_CACHE) { 358 int base = (foff + off) & PAGE_MASK; 359 if (vm_page_is_valid(m, base, size) == 0) 360 bp->b_flags &= ~B_CACHE; 361 } 362 } 363 364 /* 365 * bd_speedup() 366 * 367 * Spank the buf_daemon[_hw] if the total dirty buffer space exceeds the 368 * low water mark. 369 * 370 * MPSAFE 371 */ 372 static __inline__ 373 void 374 bd_speedup(void) 375 { 376 if (dirtybufspace < lodirtybufspace && dirtybufcount < nbuf / 2) 377 return; 378 379 if (bd_request == 0 && 380 (dirtybufspace - dirtybufspacehw > lodirtybufspace / 2 || 381 dirtybufcount - dirtybufcounthw >= nbuf / 2)) { 382 spin_lock_wr(&needsbuffer_spin); 383 bd_request = 1; 384 spin_unlock_wr(&needsbuffer_spin); 385 wakeup(&bd_request); 386 } 387 if (bd_request_hw == 0 && 388 (dirtybufspacehw > lodirtybufspace / 2 || 389 dirtybufcounthw >= nbuf / 2)) { 390 spin_lock_wr(&needsbuffer_spin); 391 bd_request_hw = 1; 392 spin_unlock_wr(&needsbuffer_spin); 393 wakeup(&bd_request_hw); 394 } 395 } 396 397 /* 398 * bd_heatup() 399 * 400 * Get the buf_daemon heated up when the number of running and dirty 401 * buffers exceeds the mid-point. 402 * 403 * Return the total number of dirty bytes past the second mid point 404 * as a measure of how much excess dirty data there is in the system. 405 * 406 * MPSAFE 407 */ 408 int 409 bd_heatup(void) 410 { 411 int mid1; 412 int mid2; 413 int totalspace; 414 415 mid1 = lodirtybufspace + (hidirtybufspace - lodirtybufspace) / 2; 416 417 totalspace = runningbufspace + dirtybufspace; 418 if (totalspace >= mid1 || dirtybufcount >= nbuf / 2) { 419 bd_speedup(); 420 mid2 = mid1 + (hidirtybufspace - mid1) / 2; 421 if (totalspace >= mid2) 422 return(totalspace - mid2); 423 } 424 return(0); 425 } 426 427 /* 428 * bd_wait() 429 * 430 * Wait for the buffer cache to flush (totalspace) bytes worth of 431 * buffers, then return. 432 * 433 * Regardless this function blocks while the number of dirty buffers 434 * exceeds hidirtybufspace. 435 * 436 * MPSAFE 437 */ 438 void 439 bd_wait(int totalspace) 440 { 441 u_int i; 442 int count; 443 444 if (curthread == bufdaemonhw_td || curthread == bufdaemon_td) 445 return; 446 447 while (totalspace > 0) { 448 bd_heatup(); 449 if (totalspace > runningbufspace + dirtybufspace) 450 totalspace = runningbufspace + dirtybufspace; 451 count = totalspace / BKVASIZE; 452 if (count >= BD_WAKE_SIZE) 453 count = BD_WAKE_SIZE - 1; 454 455 spin_lock_wr(&needsbuffer_spin); 456 i = (bd_wake_index + count) & BD_WAKE_MASK; 457 ++bd_wake_ary[i]; 458 tsleep_interlock(&bd_wake_ary[i], 0); 459 spin_unlock_wr(&needsbuffer_spin); 460 tsleep(&bd_wake_ary[i], PINTERLOCKED, "flstik", hz); 461 462 totalspace = runningbufspace + dirtybufspace - hidirtybufspace; 463 } 464 } 465 466 /* 467 * bd_signal() 468 * 469 * This function is called whenever runningbufspace or dirtybufspace 470 * is reduced. Track threads waiting for run+dirty buffer I/O 471 * complete. 472 * 473 * MPSAFE 474 */ 475 static void 476 bd_signal(int totalspace) 477 { 478 u_int i; 479 480 if (totalspace > 0) { 481 if (totalspace > BKVASIZE * BD_WAKE_SIZE) 482 totalspace = BKVASIZE * BD_WAKE_SIZE; 483 spin_lock_wr(&needsbuffer_spin); 484 while (totalspace > 0) { 485 i = bd_wake_index++; 486 i &= BD_WAKE_MASK; 487 if (bd_wake_ary[i]) { 488 bd_wake_ary[i] = 0; 489 spin_unlock_wr(&needsbuffer_spin); 490 wakeup(&bd_wake_ary[i]); 491 spin_lock_wr(&needsbuffer_spin); 492 } 493 totalspace -= BKVASIZE; 494 } 495 spin_unlock_wr(&needsbuffer_spin); 496 } 497 } 498 499 /* 500 * BIO tracking support routines. 501 * 502 * Release a ref on a bio_track. Wakeup requests are atomically released 503 * along with the last reference so bk_active will never wind up set to 504 * only 0x80000000. 505 * 506 * MPSAFE 507 */ 508 static 509 void 510 bio_track_rel(struct bio_track *track) 511 { 512 int active; 513 int desired; 514 515 /* 516 * Shortcut 517 */ 518 active = track->bk_active; 519 if (active == 1 && atomic_cmpset_int(&track->bk_active, 1, 0)) 520 return; 521 522 /* 523 * Full-on. Note that the wait flag is only atomically released on 524 * the 1->0 count transition. 525 * 526 * We check for a negative count transition using bit 30 since bit 31 527 * has a different meaning. 528 */ 529 for (;;) { 530 desired = (active & 0x7FFFFFFF) - 1; 531 if (desired) 532 desired |= active & 0x80000000; 533 if (atomic_cmpset_int(&track->bk_active, active, desired)) { 534 if (desired & 0x40000000) 535 panic("bio_track_rel: bad count: %p\n", track); 536 if (active & 0x80000000) 537 wakeup(track); 538 break; 539 } 540 active = track->bk_active; 541 } 542 } 543 544 /* 545 * Wait for the tracking count to reach 0. 546 * 547 * Use atomic ops such that the wait flag is only set atomically when 548 * bk_active is non-zero. 549 * 550 * MPSAFE 551 */ 552 int 553 bio_track_wait(struct bio_track *track, int slp_flags, int slp_timo) 554 { 555 int active; 556 int desired; 557 int error; 558 559 /* 560 * Shortcut 561 */ 562 if (track->bk_active == 0) 563 return(0); 564 565 /* 566 * Full-on. Note that the wait flag may only be atomically set if 567 * the active count is non-zero. 568 */ 569 error = 0; 570 while ((active = track->bk_active) != 0) { 571 desired = active | 0x80000000; 572 tsleep_interlock(track, slp_flags); 573 if (active == desired || 574 atomic_cmpset_int(&track->bk_active, active, desired)) { 575 error = tsleep(track, slp_flags | PINTERLOCKED, 576 "iowait", slp_timo); 577 if (error) 578 break; 579 } 580 } 581 return (error); 582 } 583 584 /* 585 * bufinit: 586 * 587 * Load time initialisation of the buffer cache, called from machine 588 * dependant initialization code. 589 */ 590 void 591 bufinit(void) 592 { 593 struct buf *bp; 594 vm_offset_t bogus_offset; 595 int i; 596 597 spin_init(&needsbuffer_spin); 598 599 /* next, make a null set of free lists */ 600 for (i = 0; i < BUFFER_QUEUES; i++) 601 TAILQ_INIT(&bufqueues[i]); 602 603 /* finally, initialize each buffer header and stick on empty q */ 604 for (i = 0; i < nbuf; i++) { 605 bp = &buf[i]; 606 bzero(bp, sizeof *bp); 607 bp->b_flags = B_INVAL; /* we're just an empty header */ 608 bp->b_cmd = BUF_CMD_DONE; 609 bp->b_qindex = BQUEUE_EMPTY; 610 initbufbio(bp); 611 xio_init(&bp->b_xio); 612 buf_dep_init(bp); 613 BUF_LOCKINIT(bp); 614 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_EMPTY], bp, b_freelist); 615 } 616 617 /* 618 * maxbufspace is the absolute maximum amount of buffer space we are 619 * allowed to reserve in KVM and in real terms. The absolute maximum 620 * is nominally used by buf_daemon. hibufspace is the nominal maximum 621 * used by most other processes. The differential is required to 622 * ensure that buf_daemon is able to run when other processes might 623 * be blocked waiting for buffer space. 624 * 625 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 626 * this may result in KVM fragmentation which is not handled optimally 627 * by the system. 628 */ 629 maxbufspace = nbuf * BKVASIZE; 630 hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 631 lobufspace = hibufspace - MAXBSIZE; 632 633 lorunningspace = 512 * 1024; 634 /* hirunningspace -- see below */ 635 636 /* 637 * Limit the amount of malloc memory since it is wired permanently 638 * into the kernel space. Even though this is accounted for in 639 * the buffer allocation, we don't want the malloced region to grow 640 * uncontrolled. The malloc scheme improves memory utilization 641 * significantly on average (small) directories. 642 */ 643 maxbufmallocspace = hibufspace / 20; 644 645 /* 646 * Reduce the chance of a deadlock occuring by limiting the number 647 * of delayed-write dirty buffers we allow to stack up. 648 * 649 * We don't want too much actually queued to the device at once 650 * (XXX this needs to be per-mount!), because the buffers will 651 * wind up locked for a very long period of time while the I/O 652 * drains. 653 */ 654 hidirtybufspace = hibufspace / 2; /* dirty + running */ 655 hirunningspace = hibufspace / 16; /* locked & queued to device */ 656 if (hirunningspace < 1024 * 1024) 657 hirunningspace = 1024 * 1024; 658 659 dirtybufspace = 0; 660 dirtybufspacehw = 0; 661 662 lodirtybufspace = hidirtybufspace / 2; 663 664 /* 665 * Maximum number of async ops initiated per buf_daemon loop. This is 666 * somewhat of a hack at the moment, we really need to limit ourselves 667 * based on the number of bytes of I/O in-transit that were initiated 668 * from buf_daemon. 669 */ 670 671 bogus_offset = kmem_alloc_pageable(&kernel_map, PAGE_SIZE); 672 bogus_page = vm_page_alloc(&kernel_object, 673 (bogus_offset >> PAGE_SHIFT), 674 VM_ALLOC_NORMAL); 675 vmstats.v_wire_count++; 676 677 } 678 679 /* 680 * Initialize the embedded bio structures 681 */ 682 void 683 initbufbio(struct buf *bp) 684 { 685 bp->b_bio1.bio_buf = bp; 686 bp->b_bio1.bio_prev = NULL; 687 bp->b_bio1.bio_offset = NOOFFSET; 688 bp->b_bio1.bio_next = &bp->b_bio2; 689 bp->b_bio1.bio_done = NULL; 690 bp->b_bio1.bio_flags = 0; 691 692 bp->b_bio2.bio_buf = bp; 693 bp->b_bio2.bio_prev = &bp->b_bio1; 694 bp->b_bio2.bio_offset = NOOFFSET; 695 bp->b_bio2.bio_next = NULL; 696 bp->b_bio2.bio_done = NULL; 697 bp->b_bio2.bio_flags = 0; 698 } 699 700 /* 701 * Reinitialize the embedded bio structures as well as any additional 702 * translation cache layers. 703 */ 704 void 705 reinitbufbio(struct buf *bp) 706 { 707 struct bio *bio; 708 709 for (bio = &bp->b_bio1; bio; bio = bio->bio_next) { 710 bio->bio_done = NULL; 711 bio->bio_offset = NOOFFSET; 712 } 713 } 714 715 /* 716 * Push another BIO layer onto an existing BIO and return it. The new 717 * BIO layer may already exist, holding cached translation data. 718 */ 719 struct bio * 720 push_bio(struct bio *bio) 721 { 722 struct bio *nbio; 723 724 if ((nbio = bio->bio_next) == NULL) { 725 int index = bio - &bio->bio_buf->b_bio_array[0]; 726 if (index >= NBUF_BIO - 1) { 727 panic("push_bio: too many layers bp %p\n", 728 bio->bio_buf); 729 } 730 nbio = &bio->bio_buf->b_bio_array[index + 1]; 731 bio->bio_next = nbio; 732 nbio->bio_prev = bio; 733 nbio->bio_buf = bio->bio_buf; 734 nbio->bio_offset = NOOFFSET; 735 nbio->bio_done = NULL; 736 nbio->bio_next = NULL; 737 } 738 KKASSERT(nbio->bio_done == NULL); 739 return(nbio); 740 } 741 742 /* 743 * Pop a BIO translation layer, returning the previous layer. The 744 * must have been previously pushed. 745 */ 746 struct bio * 747 pop_bio(struct bio *bio) 748 { 749 return(bio->bio_prev); 750 } 751 752 void 753 clearbiocache(struct bio *bio) 754 { 755 while (bio) { 756 bio->bio_offset = NOOFFSET; 757 bio = bio->bio_next; 758 } 759 } 760 761 /* 762 * bfreekva: 763 * 764 * Free the KVA allocation for buffer 'bp'. 765 * 766 * Must be called from a critical section as this is the only locking for 767 * buffer_map. 768 * 769 * Since this call frees up buffer space, we call bufspacewakeup(). 770 * 771 * MPALMOSTSAFE 772 */ 773 static void 774 bfreekva(struct buf *bp) 775 { 776 int count; 777 778 if (bp->b_kvasize) { 779 get_mplock(); 780 ++buffreekvacnt; 781 count = vm_map_entry_reserve(MAP_RESERVE_COUNT); 782 vm_map_lock(&buffer_map); 783 bufspace -= bp->b_kvasize; 784 vm_map_delete(&buffer_map, 785 (vm_offset_t) bp->b_kvabase, 786 (vm_offset_t) bp->b_kvabase + bp->b_kvasize, 787 &count 788 ); 789 vm_map_unlock(&buffer_map); 790 vm_map_entry_release(count); 791 bp->b_kvasize = 0; 792 bufspacewakeup(); 793 rel_mplock(); 794 } 795 } 796 797 /* 798 * bremfree: 799 * 800 * Remove the buffer from the appropriate free list. 801 */ 802 static __inline void 803 _bremfree(struct buf *bp) 804 { 805 if (bp->b_qindex != BQUEUE_NONE) { 806 KASSERT(BUF_REFCNTNB(bp) == 1, 807 ("bremfree: bp %p not locked",bp)); 808 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 809 bp->b_qindex = BQUEUE_NONE; 810 } else { 811 if (BUF_REFCNTNB(bp) <= 1) 812 panic("bremfree: removing a buffer not on a queue"); 813 } 814 } 815 816 void 817 bremfree(struct buf *bp) 818 { 819 spin_lock_wr(&bufspin); 820 _bremfree(bp); 821 spin_unlock_wr(&bufspin); 822 } 823 824 static void 825 bremfree_locked(struct buf *bp) 826 { 827 _bremfree(bp); 828 } 829 830 /* 831 * bread: 832 * 833 * Get a buffer with the specified data. Look in the cache first. We 834 * must clear B_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 835 * is set, the buffer is valid and we do not have to do anything ( see 836 * getblk() ). 837 * 838 * MPALMOSTSAFE 839 */ 840 int 841 bread(struct vnode *vp, off_t loffset, int size, struct buf **bpp) 842 { 843 struct buf *bp; 844 845 bp = getblk(vp, loffset, size, 0, 0); 846 *bpp = bp; 847 848 /* if not found in cache, do some I/O */ 849 if ((bp->b_flags & B_CACHE) == 0) { 850 get_mplock(); 851 bp->b_flags &= ~(B_ERROR | B_EINTR | B_INVAL); 852 bp->b_cmd = BUF_CMD_READ; 853 bp->b_bio1.bio_done = biodone_sync; 854 bp->b_bio1.bio_flags |= BIO_SYNC; 855 vfs_busy_pages(vp, bp); 856 vn_strategy(vp, &bp->b_bio1); 857 rel_mplock(); 858 return (biowait(&bp->b_bio1, "biord")); 859 } 860 return (0); 861 } 862 863 /* 864 * breadn: 865 * 866 * Operates like bread, but also starts asynchronous I/O on 867 * read-ahead blocks. We must clear B_ERROR and B_INVAL prior 868 * to initiating I/O . If B_CACHE is set, the buffer is valid 869 * and we do not have to do anything. 870 * 871 * MPALMOSTSAFE 872 */ 873 int 874 breadn(struct vnode *vp, off_t loffset, int size, off_t *raoffset, 875 int *rabsize, int cnt, struct buf **bpp) 876 { 877 struct buf *bp, *rabp; 878 int i; 879 int rv = 0, readwait = 0; 880 881 *bpp = bp = getblk(vp, loffset, size, 0, 0); 882 883 /* if not found in cache, do some I/O */ 884 if ((bp->b_flags & B_CACHE) == 0) { 885 get_mplock(); 886 bp->b_flags &= ~(B_ERROR | B_EINTR | B_INVAL); 887 bp->b_cmd = BUF_CMD_READ; 888 bp->b_bio1.bio_done = biodone_sync; 889 bp->b_bio1.bio_flags |= BIO_SYNC; 890 vfs_busy_pages(vp, bp); 891 vn_strategy(vp, &bp->b_bio1); 892 ++readwait; 893 rel_mplock(); 894 } 895 896 for (i = 0; i < cnt; i++, raoffset++, rabsize++) { 897 if (inmem(vp, *raoffset)) 898 continue; 899 rabp = getblk(vp, *raoffset, *rabsize, 0, 0); 900 901 if ((rabp->b_flags & B_CACHE) == 0) { 902 get_mplock(); 903 rabp->b_flags &= ~(B_ERROR | B_EINTR | B_INVAL); 904 rabp->b_cmd = BUF_CMD_READ; 905 vfs_busy_pages(vp, rabp); 906 BUF_KERNPROC(rabp); 907 vn_strategy(vp, &rabp->b_bio1); 908 rel_mplock(); 909 } else { 910 brelse(rabp); 911 } 912 } 913 if (readwait) 914 rv = biowait(&bp->b_bio1, "biord"); 915 return (rv); 916 } 917 918 /* 919 * bwrite: 920 * 921 * Synchronous write, waits for completion. 922 * 923 * Write, release buffer on completion. (Done by iodone 924 * if async). Do not bother writing anything if the buffer 925 * is invalid. 926 * 927 * Note that we set B_CACHE here, indicating that buffer is 928 * fully valid and thus cacheable. This is true even of NFS 929 * now so we set it generally. This could be set either here 930 * or in biodone() since the I/O is synchronous. We put it 931 * here. 932 */ 933 int 934 bwrite(struct buf *bp) 935 { 936 int error; 937 938 if (bp->b_flags & B_INVAL) { 939 brelse(bp); 940 return (0); 941 } 942 if (BUF_REFCNTNB(bp) == 0) 943 panic("bwrite: buffer is not busy???"); 944 945 /* Mark the buffer clean */ 946 bundirty(bp); 947 948 bp->b_flags &= ~(B_ERROR | B_EINTR); 949 bp->b_flags |= B_CACHE; 950 bp->b_cmd = BUF_CMD_WRITE; 951 bp->b_bio1.bio_done = biodone_sync; 952 bp->b_bio1.bio_flags |= BIO_SYNC; 953 vfs_busy_pages(bp->b_vp, bp); 954 955 /* 956 * Normal bwrites pipeline writes. NOTE: b_bufsize is only 957 * valid for vnode-backed buffers. 958 */ 959 bp->b_runningbufspace = bp->b_bufsize; 960 if (bp->b_runningbufspace) { 961 runningbufspace += bp->b_runningbufspace; 962 ++runningbufcount; 963 } 964 965 vn_strategy(bp->b_vp, &bp->b_bio1); 966 error = biowait(&bp->b_bio1, "biows"); 967 brelse(bp); 968 return (error); 969 } 970 971 /* 972 * bawrite: 973 * 974 * Asynchronous write. Start output on a buffer, but do not wait for 975 * it to complete. The buffer is released when the output completes. 976 * 977 * bwrite() ( or the VOP routine anyway ) is responsible for handling 978 * B_INVAL buffers. Not us. 979 */ 980 void 981 bawrite(struct buf *bp) 982 { 983 if (bp->b_flags & B_INVAL) { 984 brelse(bp); 985 return; 986 } 987 if (BUF_REFCNTNB(bp) == 0) 988 panic("bwrite: buffer is not busy???"); 989 990 /* Mark the buffer clean */ 991 bundirty(bp); 992 993 bp->b_flags &= ~(B_ERROR | B_EINTR); 994 bp->b_flags |= B_CACHE; 995 bp->b_cmd = BUF_CMD_WRITE; 996 KKASSERT(bp->b_bio1.bio_done == NULL); 997 vfs_busy_pages(bp->b_vp, bp); 998 999 /* 1000 * Normal bwrites pipeline writes. NOTE: b_bufsize is only 1001 * valid for vnode-backed buffers. 1002 */ 1003 bp->b_runningbufspace = bp->b_bufsize; 1004 if (bp->b_runningbufspace) { 1005 runningbufspace += bp->b_runningbufspace; 1006 ++runningbufcount; 1007 } 1008 1009 BUF_KERNPROC(bp); 1010 vn_strategy(bp->b_vp, &bp->b_bio1); 1011 } 1012 1013 /* 1014 * bowrite: 1015 * 1016 * Ordered write. Start output on a buffer, and flag it so that the 1017 * device will write it in the order it was queued. The buffer is 1018 * released when the output completes. bwrite() ( or the VOP routine 1019 * anyway ) is responsible for handling B_INVAL buffers. 1020 */ 1021 int 1022 bowrite(struct buf *bp) 1023 { 1024 bp->b_flags |= B_ORDERED; 1025 bawrite(bp); 1026 return (0); 1027 } 1028 1029 /* 1030 * bdwrite: 1031 * 1032 * Delayed write. (Buffer is marked dirty). Do not bother writing 1033 * anything if the buffer is marked invalid. 1034 * 1035 * Note that since the buffer must be completely valid, we can safely 1036 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 1037 * biodone() in order to prevent getblk from writing the buffer 1038 * out synchronously. 1039 */ 1040 void 1041 bdwrite(struct buf *bp) 1042 { 1043 if (BUF_REFCNTNB(bp) == 0) 1044 panic("bdwrite: buffer is not busy"); 1045 1046 if (bp->b_flags & B_INVAL) { 1047 brelse(bp); 1048 return; 1049 } 1050 bdirty(bp); 1051 1052 /* 1053 * Set B_CACHE, indicating that the buffer is fully valid. This is 1054 * true even of NFS now. 1055 */ 1056 bp->b_flags |= B_CACHE; 1057 1058 /* 1059 * This bmap keeps the system from needing to do the bmap later, 1060 * perhaps when the system is attempting to do a sync. Since it 1061 * is likely that the indirect block -- or whatever other datastructure 1062 * that the filesystem needs is still in memory now, it is a good 1063 * thing to do this. Note also, that if the pageout daemon is 1064 * requesting a sync -- there might not be enough memory to do 1065 * the bmap then... So, this is important to do. 1066 */ 1067 if (bp->b_bio2.bio_offset == NOOFFSET) { 1068 VOP_BMAP(bp->b_vp, bp->b_loffset, &bp->b_bio2.bio_offset, 1069 NULL, NULL, BUF_CMD_WRITE); 1070 } 1071 1072 /* 1073 * Because the underlying pages may still be mapped and 1074 * writable trying to set the dirty buffer (b_dirtyoff/end) 1075 * range here will be inaccurate. 1076 * 1077 * However, we must still clean the pages to satisfy the 1078 * vnode_pager and pageout daemon, so theythink the pages 1079 * have been "cleaned". What has really occured is that 1080 * they've been earmarked for later writing by the buffer 1081 * cache. 1082 * 1083 * So we get the b_dirtyoff/end update but will not actually 1084 * depend on it (NFS that is) until the pages are busied for 1085 * writing later on. 1086 */ 1087 vfs_clean_pages(bp); 1088 bqrelse(bp); 1089 1090 /* 1091 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 1092 * due to the softdep code. 1093 */ 1094 } 1095 1096 /* 1097 * Fake write - return pages to VM system as dirty, leave the buffer clean. 1098 * This is used by tmpfs. 1099 * 1100 * It is important for any VFS using this routine to NOT use it for 1101 * IO_SYNC or IO_ASYNC operations which occur when the system really 1102 * wants to flush VM pages to backing store. 1103 */ 1104 void 1105 buwrite(struct buf *bp) 1106 { 1107 vm_page_t m; 1108 int i; 1109 1110 /* 1111 * Only works for VMIO buffers. If the buffer is already 1112 * marked for delayed-write we can't avoid the bdwrite(). 1113 */ 1114 if ((bp->b_flags & B_VMIO) == 0 || (bp->b_flags & B_DELWRI)) { 1115 bdwrite(bp); 1116 return; 1117 } 1118 1119 /* 1120 * Set valid & dirty. 1121 */ 1122 for (i = 0; i < bp->b_xio.xio_npages; i++) { 1123 m = bp->b_xio.xio_pages[i]; 1124 vfs_dirty_one_page(bp, i, m); 1125 } 1126 bqrelse(bp); 1127 } 1128 1129 /* 1130 * bdirty: 1131 * 1132 * Turn buffer into delayed write request by marking it B_DELWRI. 1133 * B_RELBUF and B_NOCACHE must be cleared. 1134 * 1135 * We reassign the buffer to itself to properly update it in the 1136 * dirty/clean lists. 1137 * 1138 * Must be called from a critical section. 1139 * The buffer must be on BQUEUE_NONE. 1140 */ 1141 void 1142 bdirty(struct buf *bp) 1143 { 1144 KASSERT(bp->b_qindex == BQUEUE_NONE, ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1145 if (bp->b_flags & B_NOCACHE) { 1146 kprintf("bdirty: clearing B_NOCACHE on buf %p\n", bp); 1147 bp->b_flags &= ~B_NOCACHE; 1148 } 1149 if (bp->b_flags & B_INVAL) { 1150 kprintf("bdirty: warning, dirtying invalid buffer %p\n", bp); 1151 } 1152 bp->b_flags &= ~B_RELBUF; 1153 1154 if ((bp->b_flags & B_DELWRI) == 0) { 1155 bp->b_flags |= B_DELWRI; 1156 reassignbuf(bp); 1157 atomic_add_int(&dirtybufcount, 1); 1158 dirtybufspace += bp->b_bufsize; 1159 if (bp->b_flags & B_HEAVY) { 1160 atomic_add_int(&dirtybufcounthw, 1); 1161 atomic_add_int(&dirtybufspacehw, bp->b_bufsize); 1162 } 1163 bd_heatup(); 1164 } 1165 } 1166 1167 /* 1168 * Set B_HEAVY, indicating that this is a heavy-weight buffer that 1169 * needs to be flushed with a different buf_daemon thread to avoid 1170 * deadlocks. B_HEAVY also imposes restrictions in getnewbuf(). 1171 */ 1172 void 1173 bheavy(struct buf *bp) 1174 { 1175 if ((bp->b_flags & B_HEAVY) == 0) { 1176 bp->b_flags |= B_HEAVY; 1177 if (bp->b_flags & B_DELWRI) { 1178 atomic_add_int(&dirtybufcounthw, 1); 1179 atomic_add_int(&dirtybufspacehw, bp->b_bufsize); 1180 } 1181 } 1182 } 1183 1184 /* 1185 * bundirty: 1186 * 1187 * Clear B_DELWRI for buffer. 1188 * 1189 * Must be called from a critical section. 1190 * 1191 * The buffer is typically on BQUEUE_NONE but there is one case in 1192 * brelse() that calls this function after placing the buffer on 1193 * a different queue. 1194 * 1195 * MPSAFE 1196 */ 1197 void 1198 bundirty(struct buf *bp) 1199 { 1200 if (bp->b_flags & B_DELWRI) { 1201 bp->b_flags &= ~B_DELWRI; 1202 reassignbuf(bp); 1203 atomic_subtract_int(&dirtybufcount, 1); 1204 atomic_subtract_int(&dirtybufspace, bp->b_bufsize); 1205 if (bp->b_flags & B_HEAVY) { 1206 atomic_subtract_int(&dirtybufcounthw, 1); 1207 atomic_subtract_int(&dirtybufspacehw, bp->b_bufsize); 1208 } 1209 bd_signal(bp->b_bufsize); 1210 } 1211 /* 1212 * Since it is now being written, we can clear its deferred write flag. 1213 */ 1214 bp->b_flags &= ~B_DEFERRED; 1215 } 1216 1217 /* 1218 * brelse: 1219 * 1220 * Release a busy buffer and, if requested, free its resources. The 1221 * buffer will be stashed in the appropriate bufqueue[] allowing it 1222 * to be accessed later as a cache entity or reused for other purposes. 1223 * 1224 * MPALMOSTSAFE 1225 */ 1226 void 1227 brelse(struct buf *bp) 1228 { 1229 #ifdef INVARIANTS 1230 int saved_flags = bp->b_flags; 1231 #endif 1232 1233 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1234 1235 /* 1236 * If B_NOCACHE is set we are being asked to destroy the buffer and 1237 * its backing store. Clear B_DELWRI. 1238 * 1239 * B_NOCACHE is set in two cases: (1) when the caller really wants 1240 * to destroy the buffer and backing store and (2) when the caller 1241 * wants to destroy the buffer and backing store after a write 1242 * completes. 1243 */ 1244 if ((bp->b_flags & (B_NOCACHE|B_DELWRI)) == (B_NOCACHE|B_DELWRI)) { 1245 bundirty(bp); 1246 } 1247 1248 if ((bp->b_flags & (B_INVAL | B_DELWRI)) == B_DELWRI) { 1249 /* 1250 * A re-dirtied buffer is only subject to destruction 1251 * by B_INVAL. B_ERROR and B_NOCACHE are ignored. 1252 */ 1253 /* leave buffer intact */ 1254 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR)) || 1255 (bp->b_bufsize <= 0)) { 1256 /* 1257 * Either a failed read or we were asked to free or not 1258 * cache the buffer. This path is reached with B_DELWRI 1259 * set only if B_INVAL is already set. B_NOCACHE governs 1260 * backing store destruction. 1261 * 1262 * NOTE: HAMMER will set B_LOCKED in buf_deallocate if the 1263 * buffer cannot be immediately freed. 1264 */ 1265 bp->b_flags |= B_INVAL; 1266 if (LIST_FIRST(&bp->b_dep) != NULL) { 1267 get_mplock(); 1268 buf_deallocate(bp); 1269 rel_mplock(); 1270 } 1271 if (bp->b_flags & B_DELWRI) { 1272 atomic_subtract_int(&dirtybufcount, 1); 1273 atomic_subtract_int(&dirtybufspace, bp->b_bufsize); 1274 if (bp->b_flags & B_HEAVY) { 1275 atomic_subtract_int(&dirtybufcounthw, 1); 1276 atomic_subtract_int(&dirtybufspacehw, bp->b_bufsize); 1277 } 1278 bd_signal(bp->b_bufsize); 1279 } 1280 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1281 } 1282 1283 /* 1284 * We must clear B_RELBUF if B_DELWRI or B_LOCKED is set. 1285 * If vfs_vmio_release() is called with either bit set, the 1286 * underlying pages may wind up getting freed causing a previous 1287 * write (bdwrite()) to get 'lost' because pages associated with 1288 * a B_DELWRI bp are marked clean. Pages associated with a 1289 * B_LOCKED buffer may be mapped by the filesystem. 1290 * 1291 * If we want to release the buffer ourselves (rather then the 1292 * originator asking us to release it), give the originator a 1293 * chance to countermand the release by setting B_LOCKED. 1294 * 1295 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1296 * if B_DELWRI is set. 1297 * 1298 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1299 * on pages to return pages to the VM page queues. 1300 */ 1301 if (bp->b_flags & (B_DELWRI | B_LOCKED)) { 1302 bp->b_flags &= ~B_RELBUF; 1303 } else if (vm_page_count_severe()) { 1304 if (LIST_FIRST(&bp->b_dep) != NULL) { 1305 get_mplock(); 1306 buf_deallocate(bp); /* can set B_LOCKED */ 1307 rel_mplock(); 1308 } 1309 if (bp->b_flags & (B_DELWRI | B_LOCKED)) 1310 bp->b_flags &= ~B_RELBUF; 1311 else 1312 bp->b_flags |= B_RELBUF; 1313 } 1314 1315 /* 1316 * Make sure b_cmd is clear. It may have already been cleared by 1317 * biodone(). 1318 * 1319 * At this point destroying the buffer is governed by the B_INVAL 1320 * or B_RELBUF flags. 1321 */ 1322 bp->b_cmd = BUF_CMD_DONE; 1323 1324 /* 1325 * VMIO buffer rundown. Make sure the VM page array is restored 1326 * after an I/O may have replaces some of the pages with bogus pages 1327 * in order to not destroy dirty pages in a fill-in read. 1328 * 1329 * Note that due to the code above, if a buffer is marked B_DELWRI 1330 * then the B_RELBUF and B_NOCACHE bits will always be clear. 1331 * B_INVAL may still be set, however. 1332 * 1333 * For clean buffers, B_INVAL or B_RELBUF will destroy the buffer 1334 * but not the backing store. B_NOCACHE will destroy the backing 1335 * store. 1336 * 1337 * Note that dirty NFS buffers contain byte-granular write ranges 1338 * and should not be destroyed w/ B_INVAL even if the backing store 1339 * is left intact. 1340 */ 1341 if (bp->b_flags & B_VMIO) { 1342 /* 1343 * Rundown for VMIO buffers which are not dirty NFS buffers. 1344 */ 1345 int i, j, resid; 1346 vm_page_t m; 1347 off_t foff; 1348 vm_pindex_t poff; 1349 vm_object_t obj; 1350 struct vnode *vp; 1351 1352 vp = bp->b_vp; 1353 1354 /* 1355 * Get the base offset and length of the buffer. Note that 1356 * in the VMIO case if the buffer block size is not 1357 * page-aligned then b_data pointer may not be page-aligned. 1358 * But our b_xio.xio_pages array *IS* page aligned. 1359 * 1360 * block sizes less then DEV_BSIZE (usually 512) are not 1361 * supported due to the page granularity bits (m->valid, 1362 * m->dirty, etc...). 1363 * 1364 * See man buf(9) for more information 1365 */ 1366 1367 resid = bp->b_bufsize; 1368 foff = bp->b_loffset; 1369 1370 get_mplock(); 1371 for (i = 0; i < bp->b_xio.xio_npages; i++) { 1372 m = bp->b_xio.xio_pages[i]; 1373 vm_page_flag_clear(m, PG_ZERO); 1374 /* 1375 * If we hit a bogus page, fixup *all* of them 1376 * now. Note that we left these pages wired 1377 * when we removed them so they had better exist, 1378 * and they cannot be ripped out from under us so 1379 * no critical section protection is necessary. 1380 */ 1381 if (m == bogus_page) { 1382 obj = vp->v_object; 1383 poff = OFF_TO_IDX(bp->b_loffset); 1384 1385 for (j = i; j < bp->b_xio.xio_npages; j++) { 1386 vm_page_t mtmp; 1387 1388 mtmp = bp->b_xio.xio_pages[j]; 1389 if (mtmp == bogus_page) { 1390 mtmp = vm_page_lookup(obj, poff + j); 1391 if (!mtmp) { 1392 panic("brelse: page missing"); 1393 } 1394 bp->b_xio.xio_pages[j] = mtmp; 1395 } 1396 } 1397 1398 if ((bp->b_flags & B_INVAL) == 0) { 1399 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 1400 bp->b_xio.xio_pages, bp->b_xio.xio_npages); 1401 } 1402 m = bp->b_xio.xio_pages[i]; 1403 } 1404 1405 /* 1406 * Invalidate the backing store if B_NOCACHE is set 1407 * (e.g. used with vinvalbuf()). If this is NFS 1408 * we impose a requirement that the block size be 1409 * a multiple of PAGE_SIZE and create a temporary 1410 * hack to basically invalidate the whole page. The 1411 * problem is that NFS uses really odd buffer sizes 1412 * especially when tracking piecemeal writes and 1413 * it also vinvalbuf()'s a lot, which would result 1414 * in only partial page validation and invalidation 1415 * here. If the file page is mmap()'d, however, 1416 * all the valid bits get set so after we invalidate 1417 * here we would end up with weird m->valid values 1418 * like 0xfc. nfs_getpages() can't handle this so 1419 * we clear all the valid bits for the NFS case 1420 * instead of just some of them. 1421 * 1422 * The real bug is the VM system having to set m->valid 1423 * to VM_PAGE_BITS_ALL for faulted-in pages, which 1424 * itself is an artifact of the whole 512-byte 1425 * granular mess that exists to support odd block 1426 * sizes and UFS meta-data block sizes (e.g. 6144). 1427 * A complete rewrite is required. 1428 * 1429 * XXX 1430 */ 1431 if (bp->b_flags & (B_NOCACHE|B_ERROR)) { 1432 int poffset = foff & PAGE_MASK; 1433 int presid; 1434 1435 presid = PAGE_SIZE - poffset; 1436 if (bp->b_vp->v_tag == VT_NFS && 1437 bp->b_vp->v_type == VREG) { 1438 ; /* entire page */ 1439 } else if (presid > resid) { 1440 presid = resid; 1441 } 1442 KASSERT(presid >= 0, ("brelse: extra page")); 1443 vm_page_set_invalid(m, poffset, presid); 1444 1445 /* 1446 * Also make sure any swap cache is removed 1447 * as it is now stale (HAMMER in particular 1448 * uses B_NOCACHE to deal with buffer 1449 * aliasing). 1450 */ 1451 swap_pager_unswapped(m); 1452 } 1453 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1454 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1455 } 1456 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1457 vfs_vmio_release(bp); 1458 rel_mplock(); 1459 } else { 1460 /* 1461 * Rundown for non-VMIO buffers. 1462 */ 1463 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1464 get_mplock(); 1465 if (bp->b_bufsize) 1466 allocbuf(bp, 0); 1467 KKASSERT (LIST_FIRST(&bp->b_dep) == NULL); 1468 if (bp->b_vp) 1469 brelvp(bp); 1470 rel_mplock(); 1471 } 1472 } 1473 1474 if (bp->b_qindex != BQUEUE_NONE) 1475 panic("brelse: free buffer onto another queue???"); 1476 if (BUF_REFCNTNB(bp) > 1) { 1477 /* Temporary panic to verify exclusive locking */ 1478 /* This panic goes away when we allow shared refs */ 1479 panic("brelse: multiple refs"); 1480 /* NOT REACHED */ 1481 return; 1482 } 1483 1484 /* 1485 * Figure out the correct queue to place the cleaned up buffer on. 1486 * Buffers placed in the EMPTY or EMPTYKVA had better already be 1487 * disassociated from their vnode. 1488 */ 1489 spin_lock_wr(&bufspin); 1490 if (bp->b_flags & B_LOCKED) { 1491 /* 1492 * Buffers that are locked are placed in the locked queue 1493 * immediately, regardless of their state. 1494 */ 1495 bp->b_qindex = BQUEUE_LOCKED; 1496 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_LOCKED], bp, b_freelist); 1497 } else if (bp->b_bufsize == 0) { 1498 /* 1499 * Buffers with no memory. Due to conditionals near the top 1500 * of brelse() such buffers should probably already be 1501 * marked B_INVAL and disassociated from their vnode. 1502 */ 1503 bp->b_flags |= B_INVAL; 1504 KASSERT(bp->b_vp == NULL, ("bp1 %p flags %08x/%08x vnode %p unexpectededly still associated!", bp, saved_flags, bp->b_flags, bp->b_vp)); 1505 KKASSERT((bp->b_flags & B_HASHED) == 0); 1506 if (bp->b_kvasize) { 1507 bp->b_qindex = BQUEUE_EMPTYKVA; 1508 } else { 1509 bp->b_qindex = BQUEUE_EMPTY; 1510 } 1511 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1512 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) { 1513 /* 1514 * Buffers with junk contents. Again these buffers had better 1515 * already be disassociated from their vnode. 1516 */ 1517 KASSERT(bp->b_vp == NULL, ("bp2 %p flags %08x/%08x vnode %p unexpectededly still associated!", bp, saved_flags, bp->b_flags, bp->b_vp)); 1518 KKASSERT((bp->b_flags & B_HASHED) == 0); 1519 bp->b_flags |= B_INVAL; 1520 bp->b_qindex = BQUEUE_CLEAN; 1521 TAILQ_INSERT_HEAD(&bufqueues[BQUEUE_CLEAN], bp, b_freelist); 1522 } else { 1523 /* 1524 * Remaining buffers. These buffers are still associated with 1525 * their vnode. 1526 */ 1527 switch(bp->b_flags & (B_DELWRI|B_HEAVY)) { 1528 case B_DELWRI: 1529 bp->b_qindex = BQUEUE_DIRTY; 1530 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_DIRTY], bp, b_freelist); 1531 break; 1532 case B_DELWRI | B_HEAVY: 1533 bp->b_qindex = BQUEUE_DIRTY_HW; 1534 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_DIRTY_HW], bp, 1535 b_freelist); 1536 break; 1537 default: 1538 /* 1539 * NOTE: Buffers are always placed at the end of the 1540 * queue. If B_AGE is not set the buffer will cycle 1541 * through the queue twice. 1542 */ 1543 bp->b_qindex = BQUEUE_CLEAN; 1544 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_CLEAN], bp, b_freelist); 1545 break; 1546 } 1547 } 1548 spin_unlock_wr(&bufspin); 1549 1550 /* 1551 * If B_INVAL, clear B_DELWRI. We've already placed the buffer 1552 * on the correct queue. 1553 */ 1554 if ((bp->b_flags & (B_INVAL|B_DELWRI)) == (B_INVAL|B_DELWRI)) 1555 bundirty(bp); 1556 1557 /* 1558 * The bp is on an appropriate queue unless locked. If it is not 1559 * locked or dirty we can wakeup threads waiting for buffer space. 1560 * 1561 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1562 * if B_INVAL is set ). 1563 */ 1564 if ((bp->b_flags & (B_LOCKED|B_DELWRI)) == 0) 1565 bufcountwakeup(); 1566 1567 /* 1568 * Something we can maybe free or reuse 1569 */ 1570 if (bp->b_bufsize || bp->b_kvasize) 1571 bufspacewakeup(); 1572 1573 /* 1574 * Clean up temporary flags and unlock the buffer. 1575 */ 1576 bp->b_flags &= ~(B_ORDERED | B_NOCACHE | B_RELBUF | B_DIRECT); 1577 BUF_UNLOCK(bp); 1578 } 1579 1580 /* 1581 * bqrelse: 1582 * 1583 * Release a buffer back to the appropriate queue but do not try to free 1584 * it. The buffer is expected to be used again soon. 1585 * 1586 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1587 * biodone() to requeue an async I/O on completion. It is also used when 1588 * known good buffers need to be requeued but we think we may need the data 1589 * again soon. 1590 * 1591 * XXX we should be able to leave the B_RELBUF hint set on completion. 1592 * 1593 * MPSAFE 1594 */ 1595 void 1596 bqrelse(struct buf *bp) 1597 { 1598 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1599 1600 if (bp->b_qindex != BQUEUE_NONE) 1601 panic("bqrelse: free buffer onto another queue???"); 1602 if (BUF_REFCNTNB(bp) > 1) { 1603 /* do not release to free list */ 1604 panic("bqrelse: multiple refs"); 1605 return; 1606 } 1607 1608 buf_act_advance(bp); 1609 1610 spin_lock_wr(&bufspin); 1611 if (bp->b_flags & B_LOCKED) { 1612 /* 1613 * Locked buffers are released to the locked queue. However, 1614 * if the buffer is dirty it will first go into the dirty 1615 * queue and later on after the I/O completes successfully it 1616 * will be released to the locked queue. 1617 */ 1618 bp->b_qindex = BQUEUE_LOCKED; 1619 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_LOCKED], bp, b_freelist); 1620 } else if (bp->b_flags & B_DELWRI) { 1621 bp->b_qindex = (bp->b_flags & B_HEAVY) ? 1622 BQUEUE_DIRTY_HW : BQUEUE_DIRTY; 1623 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1624 } else if (vm_page_count_severe()) { 1625 /* 1626 * We are too low on memory, we have to try to free the 1627 * buffer (most importantly: the wired pages making up its 1628 * backing store) *now*. 1629 */ 1630 spin_unlock_wr(&bufspin); 1631 brelse(bp); 1632 return; 1633 } else { 1634 bp->b_qindex = BQUEUE_CLEAN; 1635 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_CLEAN], bp, b_freelist); 1636 } 1637 spin_unlock_wr(&bufspin); 1638 1639 if ((bp->b_flags & B_LOCKED) == 0 && 1640 ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0)) { 1641 bufcountwakeup(); 1642 } 1643 1644 /* 1645 * Something we can maybe free or reuse. 1646 */ 1647 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1648 bufspacewakeup(); 1649 1650 /* 1651 * Final cleanup and unlock. Clear bits that are only used while a 1652 * buffer is actively locked. 1653 */ 1654 bp->b_flags &= ~(B_ORDERED | B_NOCACHE | B_RELBUF); 1655 BUF_UNLOCK(bp); 1656 } 1657 1658 /* 1659 * vfs_vmio_release: 1660 * 1661 * Return backing pages held by the buffer 'bp' back to the VM system 1662 * if possible. The pages are freed if they are no longer valid or 1663 * attempt to free if it was used for direct I/O otherwise they are 1664 * sent to the page cache. 1665 * 1666 * Pages that were marked busy are left alone and skipped. 1667 * 1668 * The KVA mapping (b_data) for the underlying pages is removed by 1669 * this function. 1670 */ 1671 static void 1672 vfs_vmio_release(struct buf *bp) 1673 { 1674 int i; 1675 vm_page_t m; 1676 1677 crit_enter(); 1678 for (i = 0; i < bp->b_xio.xio_npages; i++) { 1679 m = bp->b_xio.xio_pages[i]; 1680 bp->b_xio.xio_pages[i] = NULL; 1681 1682 /* 1683 * The VFS is telling us this is not a meta-data buffer 1684 * even if it is backed by a block device. 1685 */ 1686 if (bp->b_flags & B_NOTMETA) 1687 vm_page_flag_set(m, PG_NOTMETA); 1688 1689 /* 1690 * This is a very important bit of code. We try to track 1691 * VM page use whether the pages are wired into the buffer 1692 * cache or not. While wired into the buffer cache the 1693 * bp tracks the act_count. 1694 * 1695 * We can choose to place unwired pages on the inactive 1696 * queue (0) or active queue (1). If we place too many 1697 * on the active queue the queue will cycle the act_count 1698 * on pages we'd like to keep, just from single-use pages 1699 * (such as when doing a tar-up or file scan). 1700 */ 1701 if (bp->b_act_count < vm_cycle_point) 1702 vm_page_unwire(m, 0); 1703 else 1704 vm_page_unwire(m, 1); 1705 1706 /* 1707 * We don't mess with busy pages, it is 1708 * the responsibility of the process that 1709 * busied the pages to deal with them. 1710 */ 1711 if ((m->flags & PG_BUSY) || (m->busy != 0)) 1712 continue; 1713 1714 if (m->wire_count == 0) { 1715 vm_page_flag_clear(m, PG_ZERO); 1716 /* 1717 * Might as well free the page if we can and it has 1718 * no valid data. We also free the page if the 1719 * buffer was used for direct I/O. 1720 */ 1721 #if 0 1722 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && 1723 m->hold_count == 0) { 1724 vm_page_busy(m); 1725 vm_page_protect(m, VM_PROT_NONE); 1726 vm_page_free(m); 1727 } else 1728 #endif 1729 if (bp->b_flags & B_DIRECT) { 1730 vm_page_try_to_free(m); 1731 } else if (vm_page_count_severe()) { 1732 m->act_count = bp->b_act_count; 1733 vm_page_try_to_cache(m); 1734 } else { 1735 m->act_count = bp->b_act_count; 1736 } 1737 } 1738 } 1739 crit_exit(); 1740 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_xio.xio_npages); 1741 if (bp->b_bufsize) { 1742 bufspacewakeup(); 1743 bp->b_bufsize = 0; 1744 } 1745 bp->b_xio.xio_npages = 0; 1746 bp->b_flags &= ~B_VMIO; 1747 KKASSERT (LIST_FIRST(&bp->b_dep) == NULL); 1748 if (bp->b_vp) { 1749 get_mplock(); 1750 brelvp(bp); 1751 rel_mplock(); 1752 } 1753 } 1754 1755 /* 1756 * vfs_bio_awrite: 1757 * 1758 * Implement clustered async writes for clearing out B_DELWRI buffers. 1759 * This is much better then the old way of writing only one buffer at 1760 * a time. Note that we may not be presented with the buffers in the 1761 * correct order, so we search for the cluster in both directions. 1762 * 1763 * The buffer is locked on call. 1764 */ 1765 int 1766 vfs_bio_awrite(struct buf *bp) 1767 { 1768 int i; 1769 int j; 1770 off_t loffset = bp->b_loffset; 1771 struct vnode *vp = bp->b_vp; 1772 int nbytes; 1773 struct buf *bpa; 1774 int nwritten; 1775 int size; 1776 1777 /* 1778 * right now we support clustered writing only to regular files. If 1779 * we find a clusterable block we could be in the middle of a cluster 1780 * rather then at the beginning. 1781 * 1782 * NOTE: b_bio1 contains the logical loffset and is aliased 1783 * to b_loffset. b_bio2 contains the translated block number. 1784 */ 1785 if ((vp->v_type == VREG) && 1786 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1787 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1788 1789 size = vp->v_mount->mnt_stat.f_iosize; 1790 1791 for (i = size; i < MAXPHYS; i += size) { 1792 if ((bpa = findblk(vp, loffset + i, FINDBLK_TEST)) && 1793 BUF_REFCNT(bpa) == 0 && 1794 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == 1795 (B_DELWRI | B_CLUSTEROK)) && 1796 (bpa->b_bufsize == size)) { 1797 if ((bpa->b_bio2.bio_offset == NOOFFSET) || 1798 (bpa->b_bio2.bio_offset != 1799 bp->b_bio2.bio_offset + i)) 1800 break; 1801 } else { 1802 break; 1803 } 1804 } 1805 for (j = size; i + j <= MAXPHYS && j <= loffset; j += size) { 1806 if ((bpa = findblk(vp, loffset - j, FINDBLK_TEST)) && 1807 BUF_REFCNT(bpa) == 0 && 1808 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == 1809 (B_DELWRI | B_CLUSTEROK)) && 1810 (bpa->b_bufsize == size)) { 1811 if ((bpa->b_bio2.bio_offset == NOOFFSET) || 1812 (bpa->b_bio2.bio_offset != 1813 bp->b_bio2.bio_offset - j)) 1814 break; 1815 } else { 1816 break; 1817 } 1818 } 1819 j -= size; 1820 nbytes = (i + j); 1821 1822 /* 1823 * this is a possible cluster write 1824 */ 1825 if (nbytes != size) { 1826 BUF_UNLOCK(bp); 1827 nwritten = cluster_wbuild(vp, size, 1828 loffset - j, nbytes); 1829 return nwritten; 1830 } 1831 } 1832 1833 /* 1834 * default (old) behavior, writing out only one block 1835 * 1836 * XXX returns b_bufsize instead of b_bcount for nwritten? 1837 */ 1838 nwritten = bp->b_bufsize; 1839 bremfree(bp); 1840 bawrite(bp); 1841 1842 return nwritten; 1843 } 1844 1845 /* 1846 * getnewbuf: 1847 * 1848 * Find and initialize a new buffer header, freeing up existing buffers 1849 * in the bufqueues as necessary. The new buffer is returned locked. 1850 * 1851 * Important: B_INVAL is not set. If the caller wishes to throw the 1852 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1853 * 1854 * We block if: 1855 * We have insufficient buffer headers 1856 * We have insufficient buffer space 1857 * buffer_map is too fragmented ( space reservation fails ) 1858 * If we have to flush dirty buffers ( but we try to avoid this ) 1859 * 1860 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1861 * Instead we ask the buf daemon to do it for us. We attempt to 1862 * avoid piecemeal wakeups of the pageout daemon. 1863 * 1864 * MPALMOSTSAFE 1865 */ 1866 static struct buf * 1867 getnewbuf(int blkflags, int slptimeo, int size, int maxsize) 1868 { 1869 struct buf *bp; 1870 struct buf *nbp; 1871 int defrag = 0; 1872 int nqindex; 1873 int slpflags = (blkflags & GETBLK_PCATCH) ? PCATCH : 0; 1874 static int flushingbufs; 1875 1876 /* 1877 * We can't afford to block since we might be holding a vnode lock, 1878 * which may prevent system daemons from running. We deal with 1879 * low-memory situations by proactively returning memory and running 1880 * async I/O rather then sync I/O. 1881 */ 1882 1883 ++getnewbufcalls; 1884 --getnewbufrestarts; 1885 restart: 1886 ++getnewbufrestarts; 1887 1888 /* 1889 * Setup for scan. If we do not have enough free buffers, 1890 * we setup a degenerate case that immediately fails. Note 1891 * that if we are specially marked process, we are allowed to 1892 * dip into our reserves. 1893 * 1894 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 1895 * 1896 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 1897 * However, there are a number of cases (defragging, reusing, ...) 1898 * where we cannot backup. 1899 */ 1900 nqindex = BQUEUE_EMPTYKVA; 1901 spin_lock_wr(&bufspin); 1902 nbp = TAILQ_FIRST(&bufqueues[BQUEUE_EMPTYKVA]); 1903 1904 if (nbp == NULL) { 1905 /* 1906 * If no EMPTYKVA buffers and we are either 1907 * defragging or reusing, locate a CLEAN buffer 1908 * to free or reuse. If bufspace useage is low 1909 * skip this step so we can allocate a new buffer. 1910 */ 1911 if (defrag || bufspace >= lobufspace) { 1912 nqindex = BQUEUE_CLEAN; 1913 nbp = TAILQ_FIRST(&bufqueues[BQUEUE_CLEAN]); 1914 } 1915 1916 /* 1917 * If we could not find or were not allowed to reuse a 1918 * CLEAN buffer, check to see if it is ok to use an EMPTY 1919 * buffer. We can only use an EMPTY buffer if allocating 1920 * its KVA would not otherwise run us out of buffer space. 1921 */ 1922 if (nbp == NULL && defrag == 0 && 1923 bufspace + maxsize < hibufspace) { 1924 nqindex = BQUEUE_EMPTY; 1925 nbp = TAILQ_FIRST(&bufqueues[BQUEUE_EMPTY]); 1926 } 1927 } 1928 1929 /* 1930 * Run scan, possibly freeing data and/or kva mappings on the fly 1931 * depending. 1932 * 1933 * WARNING! bufspin is held! 1934 */ 1935 while ((bp = nbp) != NULL) { 1936 int qindex = nqindex; 1937 1938 nbp = TAILQ_NEXT(bp, b_freelist); 1939 1940 /* 1941 * BQUEUE_CLEAN - B_AGE special case. If not set the bp 1942 * cycles through the queue twice before being selected. 1943 */ 1944 if (qindex == BQUEUE_CLEAN && 1945 (bp->b_flags & B_AGE) == 0 && nbp) { 1946 bp->b_flags |= B_AGE; 1947 TAILQ_REMOVE(&bufqueues[qindex], bp, b_freelist); 1948 TAILQ_INSERT_TAIL(&bufqueues[qindex], bp, b_freelist); 1949 continue; 1950 } 1951 1952 /* 1953 * Calculate next bp ( we can only use it if we do not block 1954 * or do other fancy things ). 1955 */ 1956 if (nbp == NULL) { 1957 switch(qindex) { 1958 case BQUEUE_EMPTY: 1959 nqindex = BQUEUE_EMPTYKVA; 1960 if ((nbp = TAILQ_FIRST(&bufqueues[BQUEUE_EMPTYKVA]))) 1961 break; 1962 /* fall through */ 1963 case BQUEUE_EMPTYKVA: 1964 nqindex = BQUEUE_CLEAN; 1965 if ((nbp = TAILQ_FIRST(&bufqueues[BQUEUE_CLEAN]))) 1966 break; 1967 /* fall through */ 1968 case BQUEUE_CLEAN: 1969 /* 1970 * nbp is NULL. 1971 */ 1972 break; 1973 } 1974 } 1975 1976 /* 1977 * Sanity Checks 1978 */ 1979 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistent queue %d bp %p", qindex, bp)); 1980 1981 /* 1982 * Note: we no longer distinguish between VMIO and non-VMIO 1983 * buffers. 1984 */ 1985 1986 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); 1987 1988 /* 1989 * If we are defragging then we need a buffer with 1990 * b_kvasize != 0. XXX this situation should no longer 1991 * occur, if defrag is non-zero the buffer's b_kvasize 1992 * should also be non-zero at this point. XXX 1993 */ 1994 if (defrag && bp->b_kvasize == 0) { 1995 kprintf("Warning: defrag empty buffer %p\n", bp); 1996 continue; 1997 } 1998 1999 /* 2000 * Start freeing the bp. This is somewhat involved. nbp 2001 * remains valid only for BQUEUE_EMPTY[KVA] bp's. Buffers 2002 * on the clean list must be disassociated from their 2003 * current vnode. Buffers on the empty[kva] lists have 2004 * already been disassociated. 2005 */ 2006 2007 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) { 2008 spin_unlock_wr(&bufspin); 2009 tsleep(&bd_request, 0, "gnbxxx", hz / 100); 2010 goto restart; 2011 } 2012 if (bp->b_qindex != qindex) { 2013 spin_unlock_wr(&bufspin); 2014 kprintf("getnewbuf: warning, BUF_LOCK blocked unexpectedly on buf %p index %d->%d, race corrected\n", bp, qindex, bp->b_qindex); 2015 BUF_UNLOCK(bp); 2016 goto restart; 2017 } 2018 bremfree_locked(bp); 2019 spin_unlock_wr(&bufspin); 2020 2021 /* 2022 * Dependancies must be handled before we disassociate the 2023 * vnode. 2024 * 2025 * NOTE: HAMMER will set B_LOCKED if the buffer cannot 2026 * be immediately disassociated. HAMMER then becomes 2027 * responsible for releasing the buffer. 2028 * 2029 * NOTE: bufspin is UNLOCKED now. 2030 */ 2031 if (LIST_FIRST(&bp->b_dep) != NULL) { 2032 get_mplock(); 2033 buf_deallocate(bp); 2034 rel_mplock(); 2035 if (bp->b_flags & B_LOCKED) { 2036 bqrelse(bp); 2037 goto restart; 2038 } 2039 KKASSERT(LIST_FIRST(&bp->b_dep) == NULL); 2040 } 2041 2042 if (qindex == BQUEUE_CLEAN) { 2043 get_mplock(); 2044 if (bp->b_flags & B_VMIO) { 2045 get_mplock(); 2046 vfs_vmio_release(bp); 2047 rel_mplock(); 2048 } 2049 if (bp->b_vp) 2050 brelvp(bp); 2051 rel_mplock(); 2052 } 2053 2054 /* 2055 * NOTE: nbp is now entirely invalid. We can only restart 2056 * the scan from this point on. 2057 * 2058 * Get the rest of the buffer freed up. b_kva* is still 2059 * valid after this operation. 2060 */ 2061 2062 KASSERT(bp->b_vp == NULL, ("bp3 %p flags %08x vnode %p qindex %d unexpectededly still associated!", bp, bp->b_flags, bp->b_vp, qindex)); 2063 KKASSERT((bp->b_flags & B_HASHED) == 0); 2064 2065 /* 2066 * critical section protection is not required when 2067 * scrapping a buffer's contents because it is already 2068 * wired. 2069 */ 2070 if (bp->b_bufsize) { 2071 get_mplock(); 2072 allocbuf(bp, 0); 2073 rel_mplock(); 2074 } 2075 2076 bp->b_flags = B_BNOCLIP; 2077 bp->b_cmd = BUF_CMD_DONE; 2078 bp->b_vp = NULL; 2079 bp->b_error = 0; 2080 bp->b_resid = 0; 2081 bp->b_bcount = 0; 2082 bp->b_xio.xio_npages = 0; 2083 bp->b_dirtyoff = bp->b_dirtyend = 0; 2084 bp->b_act_count = ACT_INIT; 2085 reinitbufbio(bp); 2086 KKASSERT(LIST_FIRST(&bp->b_dep) == NULL); 2087 buf_dep_init(bp); 2088 if (blkflags & GETBLK_BHEAVY) 2089 bp->b_flags |= B_HEAVY; 2090 2091 /* 2092 * If we are defragging then free the buffer. 2093 */ 2094 if (defrag) { 2095 bp->b_flags |= B_INVAL; 2096 bfreekva(bp); 2097 brelse(bp); 2098 defrag = 0; 2099 goto restart; 2100 } 2101 2102 /* 2103 * If we are overcomitted then recover the buffer and its 2104 * KVM space. This occurs in rare situations when multiple 2105 * processes are blocked in getnewbuf() or allocbuf(). 2106 */ 2107 if (bufspace >= hibufspace) 2108 flushingbufs = 1; 2109 if (flushingbufs && bp->b_kvasize != 0) { 2110 bp->b_flags |= B_INVAL; 2111 bfreekva(bp); 2112 brelse(bp); 2113 goto restart; 2114 } 2115 if (bufspace < lobufspace) 2116 flushingbufs = 0; 2117 break; 2118 /* NOT REACHED, bufspin not held */ 2119 } 2120 2121 /* 2122 * If we exhausted our list, sleep as appropriate. We may have to 2123 * wakeup various daemons and write out some dirty buffers. 2124 * 2125 * Generally we are sleeping due to insufficient buffer space. 2126 * 2127 * NOTE: bufspin is held if bp is NULL, else it is not held. 2128 */ 2129 if (bp == NULL) { 2130 int flags; 2131 char *waitmsg; 2132 2133 spin_unlock_wr(&bufspin); 2134 if (defrag) { 2135 flags = VFS_BIO_NEED_BUFSPACE; 2136 waitmsg = "nbufkv"; 2137 } else if (bufspace >= hibufspace) { 2138 waitmsg = "nbufbs"; 2139 flags = VFS_BIO_NEED_BUFSPACE; 2140 } else { 2141 waitmsg = "newbuf"; 2142 flags = VFS_BIO_NEED_ANY; 2143 } 2144 2145 needsbuffer |= flags; 2146 bd_speedup(); /* heeeelp */ 2147 while (needsbuffer & flags) { 2148 if (tsleep(&needsbuffer, slpflags, waitmsg, slptimeo)) 2149 return (NULL); 2150 } 2151 } else { 2152 /* 2153 * We finally have a valid bp. We aren't quite out of the 2154 * woods, we still have to reserve kva space. In order 2155 * to keep fragmentation sane we only allocate kva in 2156 * BKVASIZE chunks. 2157 * 2158 * (bufspin is not held) 2159 */ 2160 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2161 2162 if (maxsize != bp->b_kvasize) { 2163 vm_offset_t addr = 0; 2164 int count; 2165 2166 bfreekva(bp); 2167 2168 get_mplock(); 2169 count = vm_map_entry_reserve(MAP_RESERVE_COUNT); 2170 vm_map_lock(&buffer_map); 2171 2172 if (vm_map_findspace(&buffer_map, 2173 vm_map_min(&buffer_map), maxsize, 2174 maxsize, 0, &addr)) { 2175 /* 2176 * Uh oh. Buffer map is too fragmented. We 2177 * must defragment the map. 2178 */ 2179 vm_map_unlock(&buffer_map); 2180 vm_map_entry_release(count); 2181 ++bufdefragcnt; 2182 defrag = 1; 2183 bp->b_flags |= B_INVAL; 2184 rel_mplock(); 2185 brelse(bp); 2186 goto restart; 2187 } 2188 if (addr) { 2189 vm_map_insert(&buffer_map, &count, 2190 NULL, 0, 2191 addr, addr + maxsize, 2192 VM_MAPTYPE_NORMAL, 2193 VM_PROT_ALL, VM_PROT_ALL, 2194 MAP_NOFAULT); 2195 2196 bp->b_kvabase = (caddr_t) addr; 2197 bp->b_kvasize = maxsize; 2198 bufspace += bp->b_kvasize; 2199 ++bufreusecnt; 2200 } 2201 vm_map_unlock(&buffer_map); 2202 vm_map_entry_release(count); 2203 rel_mplock(); 2204 } 2205 bp->b_data = bp->b_kvabase; 2206 } 2207 return(bp); 2208 } 2209 2210 /* 2211 * This routine is called in an emergency to recover VM pages from the 2212 * buffer cache by cashing in clean buffers. The idea is to recover 2213 * enough pages to be able to satisfy a stuck bio_page_alloc(). 2214 */ 2215 static int 2216 recoverbufpages(void) 2217 { 2218 struct buf *bp; 2219 int bytes = 0; 2220 2221 ++recoverbufcalls; 2222 2223 spin_lock_wr(&bufspin); 2224 while (bytes < MAXBSIZE) { 2225 bp = TAILQ_FIRST(&bufqueues[BQUEUE_CLEAN]); 2226 if (bp == NULL) 2227 break; 2228 2229 /* 2230 * BQUEUE_CLEAN - B_AGE special case. If not set the bp 2231 * cycles through the queue twice before being selected. 2232 */ 2233 if ((bp->b_flags & B_AGE) == 0 && TAILQ_NEXT(bp, b_freelist)) { 2234 bp->b_flags |= B_AGE; 2235 TAILQ_REMOVE(&bufqueues[BQUEUE_CLEAN], bp, b_freelist); 2236 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_CLEAN], 2237 bp, b_freelist); 2238 continue; 2239 } 2240 2241 /* 2242 * Sanity Checks 2243 */ 2244 KKASSERT(bp->b_qindex == BQUEUE_CLEAN); 2245 KKASSERT((bp->b_flags & B_DELWRI) == 0); 2246 2247 /* 2248 * Start freeing the bp. This is somewhat involved. 2249 * 2250 * Buffers on the clean list must be disassociated from 2251 * their current vnode 2252 */ 2253 2254 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) { 2255 kprintf("recoverbufpages: warning, locked buf %p, race corrected\n", bp); 2256 tsleep(&bd_request, 0, "gnbxxx", hz / 100); 2257 continue; 2258 } 2259 if (bp->b_qindex != BQUEUE_CLEAN) { 2260 kprintf("recoverbufpages: warning, BUF_LOCK blocked unexpectedly on buf %p index %d, race corrected\n", bp, bp->b_qindex); 2261 BUF_UNLOCK(bp); 2262 continue; 2263 } 2264 bremfree_locked(bp); 2265 spin_unlock_wr(&bufspin); 2266 2267 /* 2268 * Dependancies must be handled before we disassociate the 2269 * vnode. 2270 * 2271 * NOTE: HAMMER will set B_LOCKED if the buffer cannot 2272 * be immediately disassociated. HAMMER then becomes 2273 * responsible for releasing the buffer. 2274 */ 2275 if (LIST_FIRST(&bp->b_dep) != NULL) { 2276 buf_deallocate(bp); 2277 if (bp->b_flags & B_LOCKED) { 2278 bqrelse(bp); 2279 spin_lock_wr(&bufspin); 2280 continue; 2281 } 2282 KKASSERT(LIST_FIRST(&bp->b_dep) == NULL); 2283 } 2284 2285 bytes += bp->b_bufsize; 2286 2287 get_mplock(); 2288 if (bp->b_flags & B_VMIO) { 2289 bp->b_flags |= B_DIRECT; /* try to free pages */ 2290 vfs_vmio_release(bp); 2291 } 2292 if (bp->b_vp) 2293 brelvp(bp); 2294 2295 KKASSERT(bp->b_vp == NULL); 2296 KKASSERT((bp->b_flags & B_HASHED) == 0); 2297 2298 /* 2299 * critical section protection is not required when 2300 * scrapping a buffer's contents because it is already 2301 * wired. 2302 */ 2303 if (bp->b_bufsize) 2304 allocbuf(bp, 0); 2305 rel_mplock(); 2306 2307 bp->b_flags = B_BNOCLIP; 2308 bp->b_cmd = BUF_CMD_DONE; 2309 bp->b_vp = NULL; 2310 bp->b_error = 0; 2311 bp->b_resid = 0; 2312 bp->b_bcount = 0; 2313 bp->b_xio.xio_npages = 0; 2314 bp->b_dirtyoff = bp->b_dirtyend = 0; 2315 reinitbufbio(bp); 2316 KKASSERT(LIST_FIRST(&bp->b_dep) == NULL); 2317 buf_dep_init(bp); 2318 bp->b_flags |= B_INVAL; 2319 /* bfreekva(bp); */ 2320 brelse(bp); 2321 spin_lock_wr(&bufspin); 2322 } 2323 spin_unlock_wr(&bufspin); 2324 return(bytes); 2325 } 2326 2327 /* 2328 * buf_daemon: 2329 * 2330 * Buffer flushing daemon. Buffers are normally flushed by the 2331 * update daemon but if it cannot keep up this process starts to 2332 * take the load in an attempt to prevent getnewbuf() from blocking. 2333 * 2334 * Once a flush is initiated it does not stop until the number 2335 * of buffers falls below lodirtybuffers, but we will wake up anyone 2336 * waiting at the mid-point. 2337 */ 2338 2339 static struct kproc_desc buf_kp = { 2340 "bufdaemon", 2341 buf_daemon, 2342 &bufdaemon_td 2343 }; 2344 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, 2345 kproc_start, &buf_kp) 2346 2347 static struct kproc_desc bufhw_kp = { 2348 "bufdaemon_hw", 2349 buf_daemon_hw, 2350 &bufdaemonhw_td 2351 }; 2352 SYSINIT(bufdaemon_hw, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, 2353 kproc_start, &bufhw_kp) 2354 2355 static void 2356 buf_daemon(void) 2357 { 2358 int limit; 2359 2360 /* 2361 * This process needs to be suspended prior to shutdown sync. 2362 */ 2363 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc, 2364 bufdaemon_td, SHUTDOWN_PRI_LAST); 2365 curthread->td_flags |= TDF_SYSTHREAD; 2366 2367 /* 2368 * This process is allowed to take the buffer cache to the limit 2369 */ 2370 crit_enter(); 2371 2372 for (;;) { 2373 kproc_suspend_loop(); 2374 2375 /* 2376 * Do the flush as long as the number of dirty buffers 2377 * (including those running) exceeds lodirtybufspace. 2378 * 2379 * When flushing limit running I/O to hirunningspace 2380 * Do the flush. Limit the amount of in-transit I/O we 2381 * allow to build up, otherwise we would completely saturate 2382 * the I/O system. Wakeup any waiting processes before we 2383 * normally would so they can run in parallel with our drain. 2384 * 2385 * Our aggregate normal+HW lo water mark is lodirtybufspace, 2386 * but because we split the operation into two threads we 2387 * have to cut it in half for each thread. 2388 */ 2389 waitrunningbufspace(); 2390 limit = lodirtybufspace / 2; 2391 while (runningbufspace + dirtybufspace > limit || 2392 dirtybufcount - dirtybufcounthw >= nbuf / 2) { 2393 if (flushbufqueues(BQUEUE_DIRTY) == 0) 2394 break; 2395 if (runningbufspace < hirunningspace) 2396 continue; 2397 waitrunningbufspace(); 2398 } 2399 2400 /* 2401 * We reached our low water mark, reset the 2402 * request and sleep until we are needed again. 2403 * The sleep is just so the suspend code works. 2404 */ 2405 spin_lock_wr(&needsbuffer_spin); 2406 if (bd_request == 0) { 2407 ssleep(&bd_request, &needsbuffer_spin, 0, 2408 "psleep", hz); 2409 } 2410 bd_request = 0; 2411 spin_unlock_wr(&needsbuffer_spin); 2412 } 2413 } 2414 2415 static void 2416 buf_daemon_hw(void) 2417 { 2418 int limit; 2419 2420 /* 2421 * This process needs to be suspended prior to shutdown sync. 2422 */ 2423 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc, 2424 bufdaemonhw_td, SHUTDOWN_PRI_LAST); 2425 curthread->td_flags |= TDF_SYSTHREAD; 2426 2427 /* 2428 * This process is allowed to take the buffer cache to the limit 2429 */ 2430 crit_enter(); 2431 2432 for (;;) { 2433 kproc_suspend_loop(); 2434 2435 /* 2436 * Do the flush. Limit the amount of in-transit I/O we 2437 * allow to build up, otherwise we would completely saturate 2438 * the I/O system. Wakeup any waiting processes before we 2439 * normally would so they can run in parallel with our drain. 2440 * 2441 * Once we decide to flush push the queued I/O up to 2442 * hirunningspace in order to trigger bursting by the bioq 2443 * subsystem. 2444 * 2445 * Our aggregate normal+HW lo water mark is lodirtybufspace, 2446 * but because we split the operation into two threads we 2447 * have to cut it in half for each thread. 2448 */ 2449 waitrunningbufspace(); 2450 limit = lodirtybufspace / 2; 2451 while (runningbufspace + dirtybufspacehw > limit || 2452 dirtybufcounthw >= nbuf / 2) { 2453 if (flushbufqueues(BQUEUE_DIRTY_HW) == 0) 2454 break; 2455 if (runningbufspace < hirunningspace) 2456 continue; 2457 waitrunningbufspace(); 2458 } 2459 2460 /* 2461 * We reached our low water mark, reset the 2462 * request and sleep until we are needed again. 2463 * The sleep is just so the suspend code works. 2464 */ 2465 spin_lock_wr(&needsbuffer_spin); 2466 if (bd_request_hw == 0) { 2467 ssleep(&bd_request_hw, &needsbuffer_spin, 0, 2468 "psleep", hz); 2469 } 2470 bd_request_hw = 0; 2471 spin_unlock_wr(&needsbuffer_spin); 2472 } 2473 } 2474 2475 /* 2476 * flushbufqueues: 2477 * 2478 * Try to flush a buffer in the dirty queue. We must be careful to 2479 * free up B_INVAL buffers instead of write them, which NFS is 2480 * particularly sensitive to. 2481 * 2482 * B_RELBUF may only be set by VFSs. We do set B_AGE to indicate 2483 * that we really want to try to get the buffer out and reuse it 2484 * due to the write load on the machine. 2485 */ 2486 static int 2487 flushbufqueues(bufq_type_t q) 2488 { 2489 struct buf *bp; 2490 int r = 0; 2491 int spun; 2492 2493 spin_lock_wr(&bufspin); 2494 spun = 1; 2495 2496 bp = TAILQ_FIRST(&bufqueues[q]); 2497 while (bp) { 2498 KASSERT((bp->b_flags & B_DELWRI), 2499 ("unexpected clean buffer %p", bp)); 2500 2501 if (bp->b_flags & B_DELWRI) { 2502 if (bp->b_flags & B_INVAL) { 2503 spin_unlock_wr(&bufspin); 2504 spun = 0; 2505 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) 2506 panic("flushbufqueues: locked buf"); 2507 bremfree(bp); 2508 brelse(bp); 2509 ++r; 2510 break; 2511 } 2512 if (LIST_FIRST(&bp->b_dep) != NULL && 2513 (bp->b_flags & B_DEFERRED) == 0 && 2514 buf_countdeps(bp, 0)) { 2515 TAILQ_REMOVE(&bufqueues[q], bp, b_freelist); 2516 TAILQ_INSERT_TAIL(&bufqueues[q], bp, 2517 b_freelist); 2518 bp->b_flags |= B_DEFERRED; 2519 bp = TAILQ_FIRST(&bufqueues[q]); 2520 continue; 2521 } 2522 2523 /* 2524 * Only write it out if we can successfully lock 2525 * it. If the buffer has a dependancy, 2526 * buf_checkwrite must also return 0 for us to 2527 * be able to initate the write. 2528 * 2529 * If the buffer is flagged B_ERROR it may be 2530 * requeued over and over again, we try to 2531 * avoid a live lock. 2532 */ 2533 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) == 0) { 2534 spin_unlock_wr(&bufspin); 2535 spun = 0; 2536 if (LIST_FIRST(&bp->b_dep) != NULL && 2537 buf_checkwrite(bp)) { 2538 bremfree(bp); 2539 brelse(bp); 2540 } else if (bp->b_flags & B_ERROR) { 2541 tsleep(bp, 0, "bioer", 1); 2542 bp->b_flags &= ~B_AGE; 2543 vfs_bio_awrite(bp); 2544 } else { 2545 bp->b_flags |= B_AGE; 2546 vfs_bio_awrite(bp); 2547 } 2548 ++r; 2549 break; 2550 } 2551 } 2552 bp = TAILQ_NEXT(bp, b_freelist); 2553 } 2554 if (spun) 2555 spin_unlock_wr(&bufspin); 2556 return (r); 2557 } 2558 2559 /* 2560 * inmem: 2561 * 2562 * Returns true if no I/O is needed to access the associated VM object. 2563 * This is like findblk except it also hunts around in the VM system for 2564 * the data. 2565 * 2566 * Note that we ignore vm_page_free() races from interrupts against our 2567 * lookup, since if the caller is not protected our return value will not 2568 * be any more valid then otherwise once we exit the critical section. 2569 */ 2570 int 2571 inmem(struct vnode *vp, off_t loffset) 2572 { 2573 vm_object_t obj; 2574 vm_offset_t toff, tinc, size; 2575 vm_page_t m; 2576 2577 if (findblk(vp, loffset, FINDBLK_TEST)) 2578 return 1; 2579 if (vp->v_mount == NULL) 2580 return 0; 2581 if ((obj = vp->v_object) == NULL) 2582 return 0; 2583 2584 size = PAGE_SIZE; 2585 if (size > vp->v_mount->mnt_stat.f_iosize) 2586 size = vp->v_mount->mnt_stat.f_iosize; 2587 2588 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2589 m = vm_page_lookup(obj, OFF_TO_IDX(loffset + toff)); 2590 if (m == NULL) 2591 return 0; 2592 tinc = size; 2593 if (tinc > PAGE_SIZE - ((toff + loffset) & PAGE_MASK)) 2594 tinc = PAGE_SIZE - ((toff + loffset) & PAGE_MASK); 2595 if (vm_page_is_valid(m, 2596 (vm_offset_t) ((toff + loffset) & PAGE_MASK), tinc) == 0) 2597 return 0; 2598 } 2599 return 1; 2600 } 2601 2602 /* 2603 * findblk: 2604 * 2605 * Locate and return the specified buffer. Unless flagged otherwise, 2606 * a locked buffer will be returned if it exists or NULL if it does not. 2607 * 2608 * findblk()'d buffers are still on the bufqueues and if you intend 2609 * to use your (locked NON-TEST) buffer you need to bremfree(bp) 2610 * and possibly do other stuff to it. 2611 * 2612 * FINDBLK_TEST - Do not lock the buffer. The caller is responsible 2613 * for locking the buffer and ensuring that it remains 2614 * the desired buffer after locking. 2615 * 2616 * FINDBLK_NBLOCK - Lock the buffer non-blocking. If we are unable 2617 * to acquire the lock we return NULL, even if the 2618 * buffer exists. 2619 * 2620 * (0) - Lock the buffer blocking. 2621 * 2622 * MPSAFE 2623 */ 2624 struct buf * 2625 findblk(struct vnode *vp, off_t loffset, int flags) 2626 { 2627 lwkt_tokref vlock; 2628 struct buf *bp; 2629 int lkflags; 2630 2631 lkflags = LK_EXCLUSIVE; 2632 if (flags & FINDBLK_NBLOCK) 2633 lkflags |= LK_NOWAIT; 2634 2635 for (;;) { 2636 lwkt_gettoken(&vlock, &vp->v_token); 2637 bp = buf_rb_hash_RB_LOOKUP(&vp->v_rbhash_tree, loffset); 2638 lwkt_reltoken(&vlock); 2639 if (bp == NULL || (flags & FINDBLK_TEST)) 2640 break; 2641 if (BUF_LOCK(bp, lkflags)) { 2642 bp = NULL; 2643 break; 2644 } 2645 if (bp->b_vp == vp && bp->b_loffset == loffset) 2646 break; 2647 BUF_UNLOCK(bp); 2648 } 2649 return(bp); 2650 } 2651 2652 /* 2653 * getcacheblk: 2654 * 2655 * Similar to getblk() except only returns the buffer if it is 2656 * B_CACHE and requires no other manipulation. Otherwise NULL 2657 * is returned. 2658 * 2659 * If B_RAM is set the buffer might be just fine, but we return 2660 * NULL anyway because we want the code to fall through to the 2661 * cluster read. Otherwise read-ahead breaks. 2662 */ 2663 struct buf * 2664 getcacheblk(struct vnode *vp, off_t loffset) 2665 { 2666 struct buf *bp; 2667 2668 bp = findblk(vp, loffset, 0); 2669 if (bp) { 2670 if ((bp->b_flags & (B_INVAL | B_CACHE | B_RAM)) == B_CACHE) { 2671 bp->b_flags &= ~B_AGE; 2672 bremfree(bp); 2673 } else { 2674 BUF_UNLOCK(bp); 2675 bp = NULL; 2676 } 2677 } 2678 return (bp); 2679 } 2680 2681 /* 2682 * getblk: 2683 * 2684 * Get a block given a specified block and offset into a file/device. 2685 * B_INVAL may or may not be set on return. The caller should clear 2686 * B_INVAL prior to initiating a READ. 2687 * 2688 * IT IS IMPORTANT TO UNDERSTAND THAT IF YOU CALL GETBLK() AND B_CACHE 2689 * IS NOT SET, YOU MUST INITIALIZE THE RETURNED BUFFER, ISSUE A READ, 2690 * OR SET B_INVAL BEFORE RETIRING IT. If you retire a getblk'd buffer 2691 * without doing any of those things the system will likely believe 2692 * the buffer to be valid (especially if it is not B_VMIO), and the 2693 * next getblk() will return the buffer with B_CACHE set. 2694 * 2695 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2696 * an existing buffer. 2697 * 2698 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2699 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2700 * and then cleared based on the backing VM. If the previous buffer is 2701 * non-0-sized but invalid, B_CACHE will be cleared. 2702 * 2703 * If getblk() must create a new buffer, the new buffer is returned with 2704 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2705 * case it is returned with B_INVAL clear and B_CACHE set based on the 2706 * backing VM. 2707 * 2708 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 2709 * B_CACHE bit is clear. 2710 * 2711 * What this means, basically, is that the caller should use B_CACHE to 2712 * determine whether the buffer is fully valid or not and should clear 2713 * B_INVAL prior to issuing a read. If the caller intends to validate 2714 * the buffer by loading its data area with something, the caller needs 2715 * to clear B_INVAL. If the caller does this without issuing an I/O, 2716 * the caller should set B_CACHE ( as an optimization ), else the caller 2717 * should issue the I/O and biodone() will set B_CACHE if the I/O was 2718 * a write attempt or if it was a successfull read. If the caller 2719 * intends to issue a READ, the caller must clear B_INVAL and B_ERROR 2720 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 2721 * 2722 * getblk flags: 2723 * 2724 * GETBLK_PCATCH - catch signal if blocked, can cause NULL return 2725 * GETBLK_BHEAVY - heavy-weight buffer cache buffer 2726 * 2727 * MPALMOSTSAFE 2728 */ 2729 struct buf * 2730 getblk(struct vnode *vp, off_t loffset, int size, int blkflags, int slptimeo) 2731 { 2732 struct buf *bp; 2733 int slpflags = (blkflags & GETBLK_PCATCH) ? PCATCH : 0; 2734 int error; 2735 int lkflags; 2736 2737 if (size > MAXBSIZE) 2738 panic("getblk: size(%d) > MAXBSIZE(%d)", size, MAXBSIZE); 2739 if (vp->v_object == NULL) 2740 panic("getblk: vnode %p has no object!", vp); 2741 2742 loop: 2743 if ((bp = findblk(vp, loffset, FINDBLK_TEST)) != NULL) { 2744 /* 2745 * The buffer was found in the cache, but we need to lock it. 2746 * Even with LK_NOWAIT the lockmgr may break our critical 2747 * section, so double-check the validity of the buffer 2748 * once the lock has been obtained. 2749 */ 2750 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) { 2751 if (blkflags & GETBLK_NOWAIT) 2752 return(NULL); 2753 lkflags = LK_EXCLUSIVE | LK_SLEEPFAIL; 2754 if (blkflags & GETBLK_PCATCH) 2755 lkflags |= LK_PCATCH; 2756 error = BUF_TIMELOCK(bp, lkflags, "getblk", slptimeo); 2757 if (error) { 2758 if (error == ENOLCK) 2759 goto loop; 2760 return (NULL); 2761 } 2762 /* buffer may have changed on us */ 2763 } 2764 2765 /* 2766 * Once the buffer has been locked, make sure we didn't race 2767 * a buffer recyclement. Buffers that are no longer hashed 2768 * will have b_vp == NULL, so this takes care of that check 2769 * as well. 2770 */ 2771 if (bp->b_vp != vp || bp->b_loffset != loffset) { 2772 kprintf("Warning buffer %p (vp %p loffset %lld) " 2773 "was recycled\n", 2774 bp, vp, (long long)loffset); 2775 BUF_UNLOCK(bp); 2776 goto loop; 2777 } 2778 2779 /* 2780 * If SZMATCH any pre-existing buffer must be of the requested 2781 * size or NULL is returned. The caller absolutely does not 2782 * want getblk() to bwrite() the buffer on a size mismatch. 2783 */ 2784 if ((blkflags & GETBLK_SZMATCH) && size != bp->b_bcount) { 2785 BUF_UNLOCK(bp); 2786 return(NULL); 2787 } 2788 2789 /* 2790 * All vnode-based buffers must be backed by a VM object. 2791 */ 2792 KKASSERT(bp->b_flags & B_VMIO); 2793 KKASSERT(bp->b_cmd == BUF_CMD_DONE); 2794 bp->b_flags &= ~B_AGE; 2795 2796 /* 2797 * Make sure that B_INVAL buffers do not have a cached 2798 * block number translation. 2799 */ 2800 if ((bp->b_flags & B_INVAL) && (bp->b_bio2.bio_offset != NOOFFSET)) { 2801 kprintf("Warning invalid buffer %p (vp %p loffset %lld)" 2802 " did not have cleared bio_offset cache\n", 2803 bp, vp, (long long)loffset); 2804 clearbiocache(&bp->b_bio2); 2805 } 2806 2807 /* 2808 * The buffer is locked. B_CACHE is cleared if the buffer is 2809 * invalid. 2810 */ 2811 if (bp->b_flags & B_INVAL) 2812 bp->b_flags &= ~B_CACHE; 2813 bremfree(bp); 2814 2815 /* 2816 * Any size inconsistancy with a dirty buffer or a buffer 2817 * with a softupdates dependancy must be resolved. Resizing 2818 * the buffer in such circumstances can lead to problems. 2819 * 2820 * Dirty or dependant buffers are written synchronously. 2821 * Other types of buffers are simply released and 2822 * reconstituted as they may be backed by valid, dirty VM 2823 * pages (but not marked B_DELWRI). 2824 * 2825 * NFS NOTE: NFS buffers which straddle EOF are oddly-sized 2826 * and may be left over from a prior truncation (and thus 2827 * no longer represent the actual EOF point), so we 2828 * definitely do not want to B_NOCACHE the backing store. 2829 */ 2830 if (size != bp->b_bcount) { 2831 get_mplock(); 2832 if (bp->b_flags & B_DELWRI) { 2833 bp->b_flags |= B_RELBUF; 2834 bwrite(bp); 2835 } else if (LIST_FIRST(&bp->b_dep)) { 2836 bp->b_flags |= B_RELBUF; 2837 bwrite(bp); 2838 } else { 2839 bp->b_flags |= B_RELBUF; 2840 brelse(bp); 2841 } 2842 rel_mplock(); 2843 goto loop; 2844 } 2845 KKASSERT(size <= bp->b_kvasize); 2846 KASSERT(bp->b_loffset != NOOFFSET, 2847 ("getblk: no buffer offset")); 2848 2849 /* 2850 * A buffer with B_DELWRI set and B_CACHE clear must 2851 * be committed before we can return the buffer in 2852 * order to prevent the caller from issuing a read 2853 * ( due to B_CACHE not being set ) and overwriting 2854 * it. 2855 * 2856 * Most callers, including NFS and FFS, need this to 2857 * operate properly either because they assume they 2858 * can issue a read if B_CACHE is not set, or because 2859 * ( for example ) an uncached B_DELWRI might loop due 2860 * to softupdates re-dirtying the buffer. In the latter 2861 * case, B_CACHE is set after the first write completes, 2862 * preventing further loops. 2863 * 2864 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 2865 * above while extending the buffer, we cannot allow the 2866 * buffer to remain with B_CACHE set after the write 2867 * completes or it will represent a corrupt state. To 2868 * deal with this we set B_NOCACHE to scrap the buffer 2869 * after the write. 2870 * 2871 * XXX Should this be B_RELBUF instead of B_NOCACHE? 2872 * I'm not even sure this state is still possible 2873 * now that getblk() writes out any dirty buffers 2874 * on size changes. 2875 * 2876 * We might be able to do something fancy, like setting 2877 * B_CACHE in bwrite() except if B_DELWRI is already set, 2878 * so the below call doesn't set B_CACHE, but that gets real 2879 * confusing. This is much easier. 2880 */ 2881 2882 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 2883 get_mplock(); 2884 kprintf("getblk: Warning, bp %p loff=%jx DELWRI set " 2885 "and CACHE clear, b_flags %08x\n", 2886 bp, (intmax_t)bp->b_loffset, bp->b_flags); 2887 bp->b_flags |= B_NOCACHE; 2888 bwrite(bp); 2889 rel_mplock(); 2890 goto loop; 2891 } 2892 } else { 2893 /* 2894 * Buffer is not in-core, create new buffer. The buffer 2895 * returned by getnewbuf() is locked. Note that the returned 2896 * buffer is also considered valid (not marked B_INVAL). 2897 * 2898 * Calculating the offset for the I/O requires figuring out 2899 * the block size. We use DEV_BSIZE for VBLK or VCHR and 2900 * the mount's f_iosize otherwise. If the vnode does not 2901 * have an associated mount we assume that the passed size is 2902 * the block size. 2903 * 2904 * Note that vn_isdisk() cannot be used here since it may 2905 * return a failure for numerous reasons. Note that the 2906 * buffer size may be larger then the block size (the caller 2907 * will use block numbers with the proper multiple). Beware 2908 * of using any v_* fields which are part of unions. In 2909 * particular, in DragonFly the mount point overloading 2910 * mechanism uses the namecache only and the underlying 2911 * directory vnode is not a special case. 2912 */ 2913 int bsize, maxsize; 2914 2915 if (vp->v_type == VBLK || vp->v_type == VCHR) 2916 bsize = DEV_BSIZE; 2917 else if (vp->v_mount) 2918 bsize = vp->v_mount->mnt_stat.f_iosize; 2919 else 2920 bsize = size; 2921 2922 maxsize = size + (loffset & PAGE_MASK); 2923 maxsize = imax(maxsize, bsize); 2924 2925 bp = getnewbuf(blkflags, slptimeo, size, maxsize); 2926 if (bp == NULL) { 2927 if (slpflags || slptimeo) 2928 return NULL; 2929 goto loop; 2930 } 2931 2932 /* 2933 * Atomically insert the buffer into the hash, so that it can 2934 * be found by findblk(). 2935 * 2936 * If bgetvp() returns non-zero a collision occured, and the 2937 * bp will not be associated with the vnode. 2938 * 2939 * Make sure the translation layer has been cleared. 2940 */ 2941 bp->b_loffset = loffset; 2942 bp->b_bio2.bio_offset = NOOFFSET; 2943 /* bp->b_bio2.bio_next = NULL; */ 2944 2945 if (bgetvp(vp, bp)) { 2946 bp->b_flags |= B_INVAL; 2947 brelse(bp); 2948 goto loop; 2949 } 2950 2951 /* 2952 * All vnode-based buffers must be backed by a VM object. 2953 */ 2954 KKASSERT(vp->v_object != NULL); 2955 bp->b_flags |= B_VMIO; 2956 KKASSERT(bp->b_cmd == BUF_CMD_DONE); 2957 2958 get_mplock(); 2959 allocbuf(bp, size); 2960 rel_mplock(); 2961 } 2962 return (bp); 2963 } 2964 2965 /* 2966 * regetblk(bp) 2967 * 2968 * Reacquire a buffer that was previously released to the locked queue, 2969 * or reacquire a buffer which is interlocked by having bioops->io_deallocate 2970 * set B_LOCKED (which handles the acquisition race). 2971 * 2972 * To this end, either B_LOCKED must be set or the dependancy list must be 2973 * non-empty. 2974 * 2975 * MPSAFE 2976 */ 2977 void 2978 regetblk(struct buf *bp) 2979 { 2980 KKASSERT((bp->b_flags & B_LOCKED) || LIST_FIRST(&bp->b_dep) != NULL); 2981 BUF_LOCK(bp, LK_EXCLUSIVE | LK_RETRY); 2982 bremfree(bp); 2983 } 2984 2985 /* 2986 * geteblk: 2987 * 2988 * Get an empty, disassociated buffer of given size. The buffer is 2989 * initially set to B_INVAL. 2990 * 2991 * critical section protection is not required for the allocbuf() 2992 * call because races are impossible here. 2993 * 2994 * MPALMOSTSAFE 2995 */ 2996 struct buf * 2997 geteblk(int size) 2998 { 2999 struct buf *bp; 3000 int maxsize; 3001 3002 maxsize = (size + BKVAMASK) & ~BKVAMASK; 3003 3004 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0) 3005 ; 3006 get_mplock(); 3007 allocbuf(bp, size); 3008 rel_mplock(); 3009 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 3010 return (bp); 3011 } 3012 3013 3014 /* 3015 * allocbuf: 3016 * 3017 * This code constitutes the buffer memory from either anonymous system 3018 * memory (in the case of non-VMIO operations) or from an associated 3019 * VM object (in the case of VMIO operations). This code is able to 3020 * resize a buffer up or down. 3021 * 3022 * Note that this code is tricky, and has many complications to resolve 3023 * deadlock or inconsistant data situations. Tread lightly!!! 3024 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 3025 * the caller. Calling this code willy nilly can result in the loss of data. 3026 * 3027 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 3028 * B_CACHE for the non-VMIO case. 3029 * 3030 * This routine does not need to be called from a critical section but you 3031 * must own the buffer. 3032 * 3033 * NOTMPSAFE 3034 */ 3035 int 3036 allocbuf(struct buf *bp, int size) 3037 { 3038 int newbsize, mbsize; 3039 int i; 3040 3041 if (BUF_REFCNT(bp) == 0) 3042 panic("allocbuf: buffer not busy"); 3043 3044 if (bp->b_kvasize < size) 3045 panic("allocbuf: buffer too small"); 3046 3047 if ((bp->b_flags & B_VMIO) == 0) { 3048 caddr_t origbuf; 3049 int origbufsize; 3050 /* 3051 * Just get anonymous memory from the kernel. Don't 3052 * mess with B_CACHE. 3053 */ 3054 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3055 if (bp->b_flags & B_MALLOC) 3056 newbsize = mbsize; 3057 else 3058 newbsize = round_page(size); 3059 3060 if (newbsize < bp->b_bufsize) { 3061 /* 3062 * Malloced buffers are not shrunk 3063 */ 3064 if (bp->b_flags & B_MALLOC) { 3065 if (newbsize) { 3066 bp->b_bcount = size; 3067 } else { 3068 kfree(bp->b_data, M_BIOBUF); 3069 if (bp->b_bufsize) { 3070 bufmallocspace -= bp->b_bufsize; 3071 bufspacewakeup(); 3072 bp->b_bufsize = 0; 3073 } 3074 bp->b_data = bp->b_kvabase; 3075 bp->b_bcount = 0; 3076 bp->b_flags &= ~B_MALLOC; 3077 } 3078 return 1; 3079 } 3080 vm_hold_free_pages( 3081 bp, 3082 (vm_offset_t) bp->b_data + newbsize, 3083 (vm_offset_t) bp->b_data + bp->b_bufsize); 3084 } else if (newbsize > bp->b_bufsize) { 3085 /* 3086 * We only use malloced memory on the first allocation. 3087 * and revert to page-allocated memory when the buffer 3088 * grows. 3089 */ 3090 if ((bufmallocspace < maxbufmallocspace) && 3091 (bp->b_bufsize == 0) && 3092 (mbsize <= PAGE_SIZE/2)) { 3093 3094 bp->b_data = kmalloc(mbsize, M_BIOBUF, M_WAITOK); 3095 bp->b_bufsize = mbsize; 3096 bp->b_bcount = size; 3097 bp->b_flags |= B_MALLOC; 3098 bufmallocspace += mbsize; 3099 return 1; 3100 } 3101 origbuf = NULL; 3102 origbufsize = 0; 3103 /* 3104 * If the buffer is growing on its other-than-first 3105 * allocation, then we revert to the page-allocation 3106 * scheme. 3107 */ 3108 if (bp->b_flags & B_MALLOC) { 3109 origbuf = bp->b_data; 3110 origbufsize = bp->b_bufsize; 3111 bp->b_data = bp->b_kvabase; 3112 if (bp->b_bufsize) { 3113 bufmallocspace -= bp->b_bufsize; 3114 bufspacewakeup(); 3115 bp->b_bufsize = 0; 3116 } 3117 bp->b_flags &= ~B_MALLOC; 3118 newbsize = round_page(newbsize); 3119 } 3120 vm_hold_load_pages( 3121 bp, 3122 (vm_offset_t) bp->b_data + bp->b_bufsize, 3123 (vm_offset_t) bp->b_data + newbsize); 3124 if (origbuf) { 3125 bcopy(origbuf, bp->b_data, origbufsize); 3126 kfree(origbuf, M_BIOBUF); 3127 } 3128 } 3129 } else { 3130 vm_page_t m; 3131 int desiredpages; 3132 3133 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3134 desiredpages = ((int)(bp->b_loffset & PAGE_MASK) + 3135 newbsize + PAGE_MASK) >> PAGE_SHIFT; 3136 KKASSERT(desiredpages <= XIO_INTERNAL_PAGES); 3137 3138 if (bp->b_flags & B_MALLOC) 3139 panic("allocbuf: VMIO buffer can't be malloced"); 3140 /* 3141 * Set B_CACHE initially if buffer is 0 length or will become 3142 * 0-length. 3143 */ 3144 if (size == 0 || bp->b_bufsize == 0) 3145 bp->b_flags |= B_CACHE; 3146 3147 if (newbsize < bp->b_bufsize) { 3148 /* 3149 * DEV_BSIZE aligned new buffer size is less then the 3150 * DEV_BSIZE aligned existing buffer size. Figure out 3151 * if we have to remove any pages. 3152 */ 3153 if (desiredpages < bp->b_xio.xio_npages) { 3154 for (i = desiredpages; i < bp->b_xio.xio_npages; i++) { 3155 /* 3156 * the page is not freed here -- it 3157 * is the responsibility of 3158 * vnode_pager_setsize 3159 */ 3160 m = bp->b_xio.xio_pages[i]; 3161 KASSERT(m != bogus_page, 3162 ("allocbuf: bogus page found")); 3163 while (vm_page_sleep_busy(m, TRUE, "biodep")) 3164 ; 3165 3166 bp->b_xio.xio_pages[i] = NULL; 3167 vm_page_unwire(m, 0); 3168 } 3169 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) + 3170 (desiredpages << PAGE_SHIFT), (bp->b_xio.xio_npages - desiredpages)); 3171 bp->b_xio.xio_npages = desiredpages; 3172 } 3173 } else if (size > bp->b_bcount) { 3174 /* 3175 * We are growing the buffer, possibly in a 3176 * byte-granular fashion. 3177 */ 3178 struct vnode *vp; 3179 vm_object_t obj; 3180 vm_offset_t toff; 3181 vm_offset_t tinc; 3182 3183 /* 3184 * Step 1, bring in the VM pages from the object, 3185 * allocating them if necessary. We must clear 3186 * B_CACHE if these pages are not valid for the 3187 * range covered by the buffer. 3188 * 3189 * critical section protection is required to protect 3190 * against interrupts unbusying and freeing pages 3191 * between our vm_page_lookup() and our 3192 * busycheck/wiring call. 3193 */ 3194 vp = bp->b_vp; 3195 obj = vp->v_object; 3196 3197 crit_enter(); 3198 while (bp->b_xio.xio_npages < desiredpages) { 3199 vm_page_t m; 3200 vm_pindex_t pi; 3201 3202 pi = OFF_TO_IDX(bp->b_loffset) + bp->b_xio.xio_npages; 3203 if ((m = vm_page_lookup(obj, pi)) == NULL) { 3204 /* 3205 * note: must allocate system pages 3206 * since blocking here could intefere 3207 * with paging I/O, no matter which 3208 * process we are. 3209 */ 3210 m = bio_page_alloc(obj, pi, desiredpages - bp->b_xio.xio_npages); 3211 if (m) { 3212 vm_page_wire(m); 3213 vm_page_wakeup(m); 3214 vm_page_flag_clear(m, PG_ZERO); 3215 bp->b_flags &= ~B_CACHE; 3216 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 3217 ++bp->b_xio.xio_npages; 3218 } 3219 continue; 3220 } 3221 3222 /* 3223 * We found a page. If we have to sleep on it, 3224 * retry because it might have gotten freed out 3225 * from under us. 3226 * 3227 * We can only test PG_BUSY here. Blocking on 3228 * m->busy might lead to a deadlock: 3229 * 3230 * vm_fault->getpages->cluster_read->allocbuf 3231 * 3232 */ 3233 3234 if (vm_page_sleep_busy(m, FALSE, "pgtblk")) 3235 continue; 3236 vm_page_flag_clear(m, PG_ZERO); 3237 vm_page_wire(m); 3238 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 3239 ++bp->b_xio.xio_npages; 3240 if (bp->b_act_count < m->act_count) 3241 bp->b_act_count = m->act_count; 3242 } 3243 crit_exit(); 3244 3245 /* 3246 * Step 2. We've loaded the pages into the buffer, 3247 * we have to figure out if we can still have B_CACHE 3248 * set. Note that B_CACHE is set according to the 3249 * byte-granular range ( bcount and size ), not the 3250 * aligned range ( newbsize ). 3251 * 3252 * The VM test is against m->valid, which is DEV_BSIZE 3253 * aligned. Needless to say, the validity of the data 3254 * needs to also be DEV_BSIZE aligned. Note that this 3255 * fails with NFS if the server or some other client 3256 * extends the file's EOF. If our buffer is resized, 3257 * B_CACHE may remain set! XXX 3258 */ 3259 3260 toff = bp->b_bcount; 3261 tinc = PAGE_SIZE - ((bp->b_loffset + toff) & PAGE_MASK); 3262 3263 while ((bp->b_flags & B_CACHE) && toff < size) { 3264 vm_pindex_t pi; 3265 3266 if (tinc > (size - toff)) 3267 tinc = size - toff; 3268 3269 pi = ((bp->b_loffset & PAGE_MASK) + toff) >> 3270 PAGE_SHIFT; 3271 3272 vfs_buf_test_cache( 3273 bp, 3274 bp->b_loffset, 3275 toff, 3276 tinc, 3277 bp->b_xio.xio_pages[pi] 3278 ); 3279 toff += tinc; 3280 tinc = PAGE_SIZE; 3281 } 3282 3283 /* 3284 * Step 3, fixup the KVM pmap. Remember that 3285 * bp->b_data is relative to bp->b_loffset, but 3286 * bp->b_loffset may be offset into the first page. 3287 */ 3288 3289 bp->b_data = (caddr_t) 3290 trunc_page((vm_offset_t)bp->b_data); 3291 pmap_qenter( 3292 (vm_offset_t)bp->b_data, 3293 bp->b_xio.xio_pages, 3294 bp->b_xio.xio_npages 3295 ); 3296 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 3297 (vm_offset_t)(bp->b_loffset & PAGE_MASK)); 3298 } 3299 } 3300 3301 /* adjust space use on already-dirty buffer */ 3302 if (bp->b_flags & B_DELWRI) { 3303 dirtybufspace += newbsize - bp->b_bufsize; 3304 if (bp->b_flags & B_HEAVY) 3305 dirtybufspacehw += newbsize - bp->b_bufsize; 3306 } 3307 if (newbsize < bp->b_bufsize) 3308 bufspacewakeup(); 3309 bp->b_bufsize = newbsize; /* actual buffer allocation */ 3310 bp->b_bcount = size; /* requested buffer size */ 3311 return 1; 3312 } 3313 3314 /* 3315 * biowait: 3316 * 3317 * Wait for buffer I/O completion, returning error status. B_EINTR 3318 * is converted into an EINTR error but not cleared (since a chain 3319 * of biowait() calls may occur). 3320 * 3321 * On return bpdone() will have been called but the buffer will remain 3322 * locked and will not have been brelse()'d. 3323 * 3324 * NOTE! If a timeout is specified and ETIMEDOUT occurs the I/O is 3325 * likely still in progress on return. 3326 * 3327 * NOTE! This operation is on a BIO, not a BUF. 3328 * 3329 * NOTE! BIO_DONE is cleared by vn_strategy() 3330 * 3331 * MPSAFE 3332 */ 3333 static __inline int 3334 _biowait(struct bio *bio, const char *wmesg, int to) 3335 { 3336 struct buf *bp = bio->bio_buf; 3337 u_int32_t flags; 3338 u_int32_t nflags; 3339 int error; 3340 3341 KKASSERT(bio == &bp->b_bio1); 3342 for (;;) { 3343 flags = bio->bio_flags; 3344 if (flags & BIO_DONE) 3345 break; 3346 tsleep_interlock(bio, 0); 3347 nflags = flags | BIO_WANT; 3348 tsleep_interlock(bio, 0); 3349 if (atomic_cmpset_int(&bio->bio_flags, flags, nflags)) { 3350 if (wmesg) 3351 error = tsleep(bio, PINTERLOCKED, wmesg, to); 3352 else if (bp->b_cmd == BUF_CMD_READ) 3353 error = tsleep(bio, PINTERLOCKED, "biord", to); 3354 else 3355 error = tsleep(bio, PINTERLOCKED, "biowr", to); 3356 if (error) { 3357 kprintf("tsleep error biowait %d\n", error); 3358 return (error); 3359 } 3360 break; 3361 } 3362 } 3363 3364 /* 3365 * Finish up. 3366 */ 3367 KKASSERT(bp->b_cmd == BUF_CMD_DONE); 3368 bio->bio_flags &= ~(BIO_DONE | BIO_SYNC); 3369 if (bp->b_flags & B_EINTR) 3370 return (EINTR); 3371 if (bp->b_flags & B_ERROR) 3372 return (bp->b_error ? bp->b_error : EIO); 3373 return (0); 3374 } 3375 3376 int 3377 biowait(struct bio *bio, const char *wmesg) 3378 { 3379 return(_biowait(bio, wmesg, 0)); 3380 } 3381 3382 int 3383 biowait_timeout(struct bio *bio, const char *wmesg, int to) 3384 { 3385 return(_biowait(bio, wmesg, to)); 3386 } 3387 3388 /* 3389 * This associates a tracking count with an I/O. vn_strategy() and 3390 * dev_dstrategy() do this automatically but there are a few cases 3391 * where a vnode or device layer is bypassed when a block translation 3392 * is cached. In such cases bio_start_transaction() may be called on 3393 * the bypassed layers so the system gets an I/O in progress indication 3394 * for those higher layers. 3395 */ 3396 void 3397 bio_start_transaction(struct bio *bio, struct bio_track *track) 3398 { 3399 bio->bio_track = track; 3400 bio_track_ref(track); 3401 } 3402 3403 /* 3404 * Initiate I/O on a vnode. 3405 * 3406 * SWAPCACHE OPERATION: 3407 * 3408 * Real buffer cache buffers have a non-NULL bp->b_vp. Unfortunately 3409 * devfs also uses b_vp for fake buffers so we also have to check 3410 * that B_PAGING is 0. In this case the passed 'vp' is probably the 3411 * underlying block device. The swap assignments are related to the 3412 * buffer cache buffer's b_vp, not the passed vp. 3413 * 3414 * The passed vp == bp->b_vp only in the case where the strategy call 3415 * is made on the vp itself for its own buffers (a regular file or 3416 * block device vp). The filesystem usually then re-calls vn_strategy() 3417 * after translating the request to an underlying device. 3418 * 3419 * Cluster buffers set B_CLUSTER and the passed vp is the vp of the 3420 * underlying buffer cache buffers. 3421 * 3422 * We can only deal with page-aligned buffers at the moment, because 3423 * we can't tell what the real dirty state for pages straddling a buffer 3424 * are. 3425 * 3426 * In order to call swap_pager_strategy() we must provide the VM object 3427 * and base offset for the underlying buffer cache pages so it can find 3428 * the swap blocks. 3429 */ 3430 void 3431 vn_strategy(struct vnode *vp, struct bio *bio) 3432 { 3433 struct bio_track *track; 3434 struct buf *bp = bio->bio_buf; 3435 3436 KKASSERT(bp->b_cmd != BUF_CMD_DONE); 3437 3438 /* 3439 * Handle the swap cache intercept. 3440 */ 3441 if (vn_cache_strategy(vp, bio)) 3442 return; 3443 3444 /* 3445 * Otherwise do the operation through the filesystem 3446 */ 3447 if (bp->b_cmd == BUF_CMD_READ) 3448 track = &vp->v_track_read; 3449 else 3450 track = &vp->v_track_write; 3451 KKASSERT((bio->bio_flags & BIO_DONE) == 0); 3452 bio->bio_track = track; 3453 bio_track_ref(track); 3454 vop_strategy(*vp->v_ops, vp, bio); 3455 } 3456 3457 int 3458 vn_cache_strategy(struct vnode *vp, struct bio *bio) 3459 { 3460 struct buf *bp = bio->bio_buf; 3461 struct bio *nbio; 3462 vm_object_t object; 3463 vm_page_t m; 3464 int i; 3465 3466 /* 3467 * Is this buffer cache buffer suitable for reading from 3468 * the swap cache? 3469 */ 3470 if (vm_swapcache_read_enable == 0 || 3471 bp->b_cmd != BUF_CMD_READ || 3472 ((bp->b_flags & B_CLUSTER) == 0 && 3473 (bp->b_vp == NULL || (bp->b_flags & B_PAGING))) || 3474 ((int)bp->b_loffset & PAGE_MASK) != 0 || 3475 (bp->b_bcount & PAGE_MASK) != 0) { 3476 return(0); 3477 } 3478 3479 /* 3480 * Figure out the original VM object (it will match the underlying 3481 * VM pages). Note that swap cached data uses page indices relative 3482 * to that object, not relative to bio->bio_offset. 3483 */ 3484 if (bp->b_flags & B_CLUSTER) 3485 object = vp->v_object; 3486 else 3487 object = bp->b_vp->v_object; 3488 3489 /* 3490 * In order to be able to use the swap cache all underlying VM 3491 * pages must be marked as such, and we can't have any bogus pages. 3492 */ 3493 for (i = 0; i < bp->b_xio.xio_npages; ++i) { 3494 m = bp->b_xio.xio_pages[i]; 3495 if ((m->flags & PG_SWAPPED) == 0) 3496 break; 3497 if (m == bogus_page) 3498 break; 3499 } 3500 3501 /* 3502 * If we are good then issue the I/O using swap_pager_strategy() 3503 */ 3504 if (i == bp->b_xio.xio_npages) { 3505 m = bp->b_xio.xio_pages[0]; 3506 nbio = push_bio(bio); 3507 nbio->bio_offset = ptoa(m->pindex); 3508 KKASSERT(m->object == object); 3509 swap_pager_strategy(object, nbio); 3510 return(1); 3511 } 3512 return(0); 3513 } 3514 3515 /* 3516 * bpdone: 3517 * 3518 * Finish I/O on a buffer after all BIOs have been processed. 3519 * Called when the bio chain is exhausted or by biowait. If called 3520 * by biowait, elseit is typically 0. 3521 * 3522 * bpdone is also responsible for setting B_CACHE in a B_VMIO bp. 3523 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3524 * assuming B_INVAL is clear. 3525 * 3526 * For the VMIO case, we set B_CACHE if the op was a read and no 3527 * read error occured, or if the op was a write. B_CACHE is never 3528 * set if the buffer is invalid or otherwise uncacheable. 3529 * 3530 * bpdone does not mess with B_INVAL, allowing the I/O routine or the 3531 * initiator to leave B_INVAL set to brelse the buffer out of existance 3532 * in the biodone routine. 3533 */ 3534 void 3535 bpdone(struct buf *bp, int elseit) 3536 { 3537 buf_cmd_t cmd; 3538 3539 KASSERT(BUF_REFCNTNB(bp) > 0, 3540 ("biodone: bp %p not busy %d", bp, BUF_REFCNTNB(bp))); 3541 KASSERT(bp->b_cmd != BUF_CMD_DONE, 3542 ("biodone: bp %p already done!", bp)); 3543 3544 /* 3545 * No more BIOs are left. All completion functions have been dealt 3546 * with, now we clean up the buffer. 3547 */ 3548 cmd = bp->b_cmd; 3549 bp->b_cmd = BUF_CMD_DONE; 3550 3551 /* 3552 * Only reads and writes are processed past this point. 3553 */ 3554 if (cmd != BUF_CMD_READ && cmd != BUF_CMD_WRITE) { 3555 if (cmd == BUF_CMD_FREEBLKS) 3556 bp->b_flags |= B_NOCACHE; 3557 if (elseit) 3558 brelse(bp); 3559 return; 3560 } 3561 3562 /* 3563 * Warning: softupdates may re-dirty the buffer, and HAMMER can do 3564 * a lot worse. XXX - move this above the clearing of b_cmd 3565 */ 3566 if (LIST_FIRST(&bp->b_dep) != NULL) 3567 buf_complete(bp); 3568 3569 /* 3570 * A failed write must re-dirty the buffer unless B_INVAL 3571 * was set. Only applicable to normal buffers (with VPs). 3572 * vinum buffers may not have a vp. 3573 */ 3574 if (cmd == BUF_CMD_WRITE && 3575 (bp->b_flags & (B_ERROR | B_INVAL)) == B_ERROR) { 3576 bp->b_flags &= ~B_NOCACHE; 3577 if (bp->b_vp) 3578 bdirty(bp); 3579 } 3580 3581 if (bp->b_flags & B_VMIO) { 3582 int i; 3583 vm_ooffset_t foff; 3584 vm_page_t m; 3585 vm_object_t obj; 3586 int iosize; 3587 struct vnode *vp = bp->b_vp; 3588 3589 obj = vp->v_object; 3590 3591 #if defined(VFS_BIO_DEBUG) 3592 if (vp->v_auxrefs == 0) 3593 panic("biodone: zero vnode hold count"); 3594 if ((vp->v_flag & VOBJBUF) == 0) 3595 panic("biodone: vnode is not setup for merged cache"); 3596 #endif 3597 3598 foff = bp->b_loffset; 3599 KASSERT(foff != NOOFFSET, ("biodone: no buffer offset")); 3600 KASSERT(obj != NULL, ("biodone: missing VM object")); 3601 3602 #if defined(VFS_BIO_DEBUG) 3603 if (obj->paging_in_progress < bp->b_xio.xio_npages) { 3604 kprintf("biodone: paging in progress(%d) < bp->b_xio.xio_npages(%d)\n", 3605 obj->paging_in_progress, bp->b_xio.xio_npages); 3606 } 3607 #endif 3608 3609 /* 3610 * Set B_CACHE if the op was a normal read and no error 3611 * occured. B_CACHE is set for writes in the b*write() 3612 * routines. 3613 */ 3614 iosize = bp->b_bcount - bp->b_resid; 3615 if (cmd == BUF_CMD_READ && 3616 (bp->b_flags & (B_INVAL|B_NOCACHE|B_ERROR)) == 0) { 3617 bp->b_flags |= B_CACHE; 3618 } 3619 3620 crit_enter(); 3621 get_mplock(); 3622 for (i = 0; i < bp->b_xio.xio_npages; i++) { 3623 int bogusflag = 0; 3624 int resid; 3625 3626 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 3627 if (resid > iosize) 3628 resid = iosize; 3629 3630 /* 3631 * cleanup bogus pages, restoring the originals. Since 3632 * the originals should still be wired, we don't have 3633 * to worry about interrupt/freeing races destroying 3634 * the VM object association. 3635 */ 3636 m = bp->b_xio.xio_pages[i]; 3637 if (m == bogus_page) { 3638 bogusflag = 1; 3639 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3640 if (m == NULL) 3641 panic("biodone: page disappeared"); 3642 bp->b_xio.xio_pages[i] = m; 3643 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3644 bp->b_xio.xio_pages, bp->b_xio.xio_npages); 3645 } 3646 #if defined(VFS_BIO_DEBUG) 3647 if (OFF_TO_IDX(foff) != m->pindex) { 3648 kprintf("biodone: foff(%lu)/m->pindex(%ld) " 3649 "mismatch\n", 3650 (unsigned long)foff, (long)m->pindex); 3651 } 3652 #endif 3653 3654 /* 3655 * In the write case, the valid and clean bits are 3656 * already changed correctly (see bdwrite()), so we 3657 * only need to do this here in the read case. 3658 */ 3659 if (cmd == BUF_CMD_READ && !bogusflag && resid > 0) { 3660 vfs_clean_one_page(bp, i, m); 3661 } 3662 vm_page_flag_clear(m, PG_ZERO); 3663 3664 /* 3665 * when debugging new filesystems or buffer I/O 3666 * methods, this is the most common error that pops 3667 * up. if you see this, you have not set the page 3668 * busy flag correctly!!! 3669 */ 3670 if (m->busy == 0) { 3671 kprintf("biodone: page busy < 0, " 3672 "pindex: %d, foff: 0x(%x,%x), " 3673 "resid: %d, index: %d\n", 3674 (int) m->pindex, (int)(foff >> 32), 3675 (int) foff & 0xffffffff, resid, i); 3676 if (!vn_isdisk(vp, NULL)) 3677 kprintf(" iosize: %ld, loffset: %lld, " 3678 "flags: 0x%08x, npages: %d\n", 3679 bp->b_vp->v_mount->mnt_stat.f_iosize, 3680 (long long)bp->b_loffset, 3681 bp->b_flags, bp->b_xio.xio_npages); 3682 else 3683 kprintf(" VDEV, loffset: %lld, flags: 0x%08x, npages: %d\n", 3684 (long long)bp->b_loffset, 3685 bp->b_flags, bp->b_xio.xio_npages); 3686 kprintf(" valid: 0x%x, dirty: 0x%x, wired: %d\n", 3687 m->valid, m->dirty, m->wire_count); 3688 panic("biodone: page busy < 0"); 3689 } 3690 vm_page_io_finish(m); 3691 vm_object_pip_subtract(obj, 1); 3692 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3693 iosize -= resid; 3694 } 3695 if (obj) 3696 vm_object_pip_wakeupn(obj, 0); 3697 rel_mplock(); 3698 crit_exit(); 3699 } 3700 3701 /* 3702 * Finish up by releasing the buffer. There are no more synchronous 3703 * or asynchronous completions, those were handled by bio_done 3704 * callbacks. 3705 */ 3706 if (elseit) { 3707 if (bp->b_flags & (B_NOCACHE|B_INVAL|B_ERROR|B_RELBUF)) 3708 brelse(bp); 3709 else 3710 bqrelse(bp); 3711 } 3712 } 3713 3714 /* 3715 * Normal biodone. 3716 */ 3717 void 3718 biodone(struct bio *bio) 3719 { 3720 struct buf *bp = bio->bio_buf; 3721 3722 runningbufwakeup(bp); 3723 3724 /* 3725 * Run up the chain of BIO's. Leave b_cmd intact for the duration. 3726 */ 3727 while (bio) { 3728 biodone_t *done_func; 3729 struct bio_track *track; 3730 3731 /* 3732 * BIO tracking. Most but not all BIOs are tracked. 3733 */ 3734 if ((track = bio->bio_track) != NULL) { 3735 bio_track_rel(track); 3736 bio->bio_track = NULL; 3737 } 3738 3739 /* 3740 * A bio_done function terminates the loop. The function 3741 * will be responsible for any further chaining and/or 3742 * buffer management. 3743 * 3744 * WARNING! The done function can deallocate the buffer! 3745 */ 3746 if ((done_func = bio->bio_done) != NULL) { 3747 bio->bio_done = NULL; 3748 done_func(bio); 3749 return; 3750 } 3751 bio = bio->bio_prev; 3752 } 3753 3754 /* 3755 * If we've run out of bio's do normal [a]synchronous completion. 3756 */ 3757 bpdone(bp, 1); 3758 } 3759 3760 /* 3761 * Synchronous biodone - this terminates a synchronous BIO. 3762 * 3763 * bpdone() is called with elseit=FALSE, leaving the buffer completed 3764 * but still locked. The caller must brelse() the buffer after waiting 3765 * for completion. 3766 */ 3767 void 3768 biodone_sync(struct bio *bio) 3769 { 3770 struct buf *bp = bio->bio_buf; 3771 int flags; 3772 int nflags; 3773 3774 KKASSERT(bio == &bp->b_bio1); 3775 bpdone(bp, 0); 3776 3777 for (;;) { 3778 flags = bio->bio_flags; 3779 nflags = (flags | BIO_DONE) & ~BIO_WANT; 3780 3781 if (atomic_cmpset_int(&bio->bio_flags, flags, nflags)) { 3782 if (flags & BIO_WANT) 3783 wakeup(bio); 3784 break; 3785 } 3786 } 3787 } 3788 3789 /* 3790 * vfs_unbusy_pages: 3791 * 3792 * This routine is called in lieu of iodone in the case of 3793 * incomplete I/O. This keeps the busy status for pages 3794 * consistant. 3795 */ 3796 void 3797 vfs_unbusy_pages(struct buf *bp) 3798 { 3799 int i; 3800 3801 runningbufwakeup(bp); 3802 if (bp->b_flags & B_VMIO) { 3803 struct vnode *vp = bp->b_vp; 3804 vm_object_t obj; 3805 3806 obj = vp->v_object; 3807 3808 for (i = 0; i < bp->b_xio.xio_npages; i++) { 3809 vm_page_t m = bp->b_xio.xio_pages[i]; 3810 3811 /* 3812 * When restoring bogus changes the original pages 3813 * should still be wired, so we are in no danger of 3814 * losing the object association and do not need 3815 * critical section protection particularly. 3816 */ 3817 if (m == bogus_page) { 3818 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_loffset) + i); 3819 if (!m) { 3820 panic("vfs_unbusy_pages: page missing"); 3821 } 3822 bp->b_xio.xio_pages[i] = m; 3823 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3824 bp->b_xio.xio_pages, bp->b_xio.xio_npages); 3825 } 3826 vm_object_pip_subtract(obj, 1); 3827 vm_page_flag_clear(m, PG_ZERO); 3828 vm_page_io_finish(m); 3829 } 3830 vm_object_pip_wakeupn(obj, 0); 3831 } 3832 } 3833 3834 /* 3835 * vfs_busy_pages: 3836 * 3837 * This routine is called before a device strategy routine. 3838 * It is used to tell the VM system that paging I/O is in 3839 * progress, and treat the pages associated with the buffer 3840 * almost as being PG_BUSY. Also the object 'paging_in_progress' 3841 * flag is handled to make sure that the object doesn't become 3842 * inconsistant. 3843 * 3844 * Since I/O has not been initiated yet, certain buffer flags 3845 * such as B_ERROR or B_INVAL may be in an inconsistant state 3846 * and should be ignored. 3847 */ 3848 void 3849 vfs_busy_pages(struct vnode *vp, struct buf *bp) 3850 { 3851 int i, bogus; 3852 struct lwp *lp = curthread->td_lwp; 3853 3854 /* 3855 * The buffer's I/O command must already be set. If reading, 3856 * B_CACHE must be 0 (double check against callers only doing 3857 * I/O when B_CACHE is 0). 3858 */ 3859 KKASSERT(bp->b_cmd != BUF_CMD_DONE); 3860 KKASSERT(bp->b_cmd == BUF_CMD_WRITE || (bp->b_flags & B_CACHE) == 0); 3861 3862 if (bp->b_flags & B_VMIO) { 3863 vm_object_t obj; 3864 3865 obj = vp->v_object; 3866 KASSERT(bp->b_loffset != NOOFFSET, 3867 ("vfs_busy_pages: no buffer offset")); 3868 3869 /* 3870 * Loop until none of the pages are busy. 3871 */ 3872 retry: 3873 for (i = 0; i < bp->b_xio.xio_npages; i++) { 3874 vm_page_t m = bp->b_xio.xio_pages[i]; 3875 3876 if (vm_page_sleep_busy(m, FALSE, "vbpage")) 3877 goto retry; 3878 } 3879 3880 /* 3881 * Setup for I/O, soft-busy the page right now because 3882 * the next loop may block. 3883 */ 3884 for (i = 0; i < bp->b_xio.xio_npages; i++) { 3885 vm_page_t m = bp->b_xio.xio_pages[i]; 3886 3887 vm_page_flag_clear(m, PG_ZERO); 3888 if ((bp->b_flags & B_CLUSTER) == 0) { 3889 vm_object_pip_add(obj, 1); 3890 vm_page_io_start(m); 3891 } 3892 } 3893 3894 /* 3895 * Adjust protections for I/O and do bogus-page mapping. 3896 * Assume that vm_page_protect() can block (it can block 3897 * if VM_PROT_NONE, don't take any chances regardless). 3898 * 3899 * In particular note that for writes we must incorporate 3900 * page dirtyness from the VM system into the buffer's 3901 * dirty range. 3902 * 3903 * For reads we theoretically must incorporate page dirtyness 3904 * from the VM system to determine if the page needs bogus 3905 * replacement, but we shortcut the test by simply checking 3906 * that all m->valid bits are set, indicating that the page 3907 * is fully valid and does not need to be re-read. For any 3908 * VM system dirtyness the page will also be fully valid 3909 * since it was mapped at one point. 3910 */ 3911 bogus = 0; 3912 for (i = 0; i < bp->b_xio.xio_npages; i++) { 3913 vm_page_t m = bp->b_xio.xio_pages[i]; 3914 3915 vm_page_flag_clear(m, PG_ZERO); /* XXX */ 3916 if (bp->b_cmd == BUF_CMD_WRITE) { 3917 /* 3918 * When readying a vnode-backed buffer for 3919 * a write we must zero-fill any invalid 3920 * portions of the backing VM pages, mark 3921 * it valid and clear related dirty bits. 3922 * 3923 * vfs_clean_one_page() incorporates any 3924 * VM dirtyness and updates the b_dirtyoff 3925 * range (after we've made the page RO). 3926 * 3927 * It is also expected that the pmap modified 3928 * bit has already been cleared by the 3929 * vm_page_protect(). We may not be able 3930 * to clear all dirty bits for a page if it 3931 * was also memory mapped (NFS). 3932 * 3933 * Finally be sure to unassign any swap-cache 3934 * backing store as it is now stale. 3935 */ 3936 vm_page_protect(m, VM_PROT_READ); 3937 vfs_clean_one_page(bp, i, m); 3938 swap_pager_unswapped(m); 3939 } else if (m->valid == VM_PAGE_BITS_ALL) { 3940 /* 3941 * When readying a vnode-backed buffer for 3942 * read we must replace any dirty pages with 3943 * a bogus page so dirty data is not destroyed 3944 * when filling gaps. 3945 * 3946 * To avoid testing whether the page is 3947 * dirty we instead test that the page was 3948 * at some point mapped (m->valid fully 3949 * valid) with the understanding that 3950 * this also covers the dirty case. 3951 */ 3952 bp->b_xio.xio_pages[i] = bogus_page; 3953 bogus++; 3954 } else if (m->valid & m->dirty) { 3955 /* 3956 * This case should not occur as partial 3957 * dirtyment can only happen if the buffer 3958 * is B_CACHE, and this code is not entered 3959 * if the buffer is B_CACHE. 3960 */ 3961 kprintf("Warning: vfs_busy_pages - page not " 3962 "fully valid! loff=%jx bpf=%08x " 3963 "idx=%d val=%02x dir=%02x\n", 3964 (intmax_t)bp->b_loffset, bp->b_flags, 3965 i, m->valid, m->dirty); 3966 vm_page_protect(m, VM_PROT_NONE); 3967 } else { 3968 /* 3969 * The page is not valid and can be made 3970 * part of the read. 3971 */ 3972 vm_page_protect(m, VM_PROT_NONE); 3973 } 3974 } 3975 if (bogus) { 3976 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3977 bp->b_xio.xio_pages, bp->b_xio.xio_npages); 3978 } 3979 } 3980 3981 /* 3982 * This is the easiest place to put the process accounting for the I/O 3983 * for now. 3984 */ 3985 if (lp != NULL) { 3986 if (bp->b_cmd == BUF_CMD_READ) 3987 lp->lwp_ru.ru_inblock++; 3988 else 3989 lp->lwp_ru.ru_oublock++; 3990 } 3991 } 3992 3993 /* 3994 * vfs_clean_pages: 3995 * 3996 * Tell the VM system that the pages associated with this buffer 3997 * are clean. This is used for delayed writes where the data is 3998 * going to go to disk eventually without additional VM intevention. 3999 * 4000 * Note that while we only really need to clean through to b_bcount, we 4001 * just go ahead and clean through to b_bufsize. 4002 */ 4003 static void 4004 vfs_clean_pages(struct buf *bp) 4005 { 4006 vm_page_t m; 4007 int i; 4008 4009 if ((bp->b_flags & B_VMIO) == 0) 4010 return; 4011 4012 KASSERT(bp->b_loffset != NOOFFSET, 4013 ("vfs_clean_pages: no buffer offset")); 4014 4015 for (i = 0; i < bp->b_xio.xio_npages; i++) { 4016 m = bp->b_xio.xio_pages[i]; 4017 vfs_clean_one_page(bp, i, m); 4018 } 4019 } 4020 4021 /* 4022 * vfs_clean_one_page: 4023 * 4024 * Set the valid bits and clear the dirty bits in a page within a 4025 * buffer. The range is restricted to the buffer's size and the 4026 * buffer's logical offset might index into the first page. 4027 * 4028 * The caller has busied or soft-busied the page and it is not mapped, 4029 * test and incorporate the dirty bits into b_dirtyoff/end before 4030 * clearing them. Note that we need to clear the pmap modified bits 4031 * after determining the the page was dirty, vm_page_set_validclean() 4032 * does not do it for us. 4033 * 4034 * This routine is typically called after a read completes (dirty should 4035 * be zero in that case as we are not called on bogus-replace pages), 4036 * or before a write is initiated. 4037 */ 4038 static void 4039 vfs_clean_one_page(struct buf *bp, int pageno, vm_page_t m) 4040 { 4041 int bcount; 4042 int xoff; 4043 int soff; 4044 int eoff; 4045 4046 /* 4047 * Calculate offset range within the page but relative to buffer's 4048 * loffset. loffset might be offset into the first page. 4049 */ 4050 xoff = (int)bp->b_loffset & PAGE_MASK; /* loffset offset into pg 0 */ 4051 bcount = bp->b_bcount + xoff; /* offset adjusted */ 4052 4053 if (pageno == 0) { 4054 soff = xoff; 4055 eoff = PAGE_SIZE; 4056 } else { 4057 soff = (pageno << PAGE_SHIFT); 4058 eoff = soff + PAGE_SIZE; 4059 } 4060 if (eoff > bcount) 4061 eoff = bcount; 4062 if (soff >= eoff) 4063 return; 4064 4065 /* 4066 * Test dirty bits and adjust b_dirtyoff/end. 4067 * 4068 * If dirty pages are incorporated into the bp any prior 4069 * B_NEEDCOMMIT state (NFS) must be cleared because the 4070 * caller has not taken into account the new dirty data. 4071 * 4072 * If the page was memory mapped the dirty bits might go beyond the 4073 * end of the buffer, but we can't really make the assumption that 4074 * a file EOF straddles the buffer (even though this is the case for 4075 * NFS if B_NEEDCOMMIT is also set). So for the purposes of clearing 4076 * B_NEEDCOMMIT we only test the dirty bits covered by the buffer. 4077 * This also saves some console spam. 4078 * 4079 * When clearing B_NEEDCOMMIT we must also clear B_CLUSTEROK, 4080 * NFS can handle huge commits but not huge writes. 4081 */ 4082 vm_page_test_dirty(m); 4083 if (m->dirty) { 4084 if ((bp->b_flags & B_NEEDCOMMIT) && 4085 (m->dirty & vm_page_bits(soff & PAGE_MASK, eoff - soff))) { 4086 if (debug_commit) 4087 kprintf("Warning: vfs_clean_one_page: bp %p " 4088 "loff=%jx,%d flgs=%08x clr B_NEEDCOMMIT" 4089 " cmd %d vd %02x/%02x x/s/e %d %d %d " 4090 "doff/end %d %d\n", 4091 bp, (intmax_t)bp->b_loffset, bp->b_bcount, 4092 bp->b_flags, bp->b_cmd, 4093 m->valid, m->dirty, xoff, soff, eoff, 4094 bp->b_dirtyoff, bp->b_dirtyend); 4095 bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK); 4096 if (debug_commit) 4097 print_backtrace(); 4098 } 4099 /* 4100 * Only clear the pmap modified bits if ALL the dirty bits 4101 * are set, otherwise the system might mis-clear portions 4102 * of a page. 4103 */ 4104 if (m->dirty == VM_PAGE_BITS_ALL && 4105 (bp->b_flags & B_NEEDCOMMIT) == 0) { 4106 pmap_clear_modify(m); 4107 } 4108 if (bp->b_dirtyoff > soff - xoff) 4109 bp->b_dirtyoff = soff - xoff; 4110 if (bp->b_dirtyend < eoff - xoff) 4111 bp->b_dirtyend = eoff - xoff; 4112 } 4113 4114 /* 4115 * Set related valid bits, clear related dirty bits. 4116 * Does not mess with the pmap modified bit. 4117 * 4118 * WARNING! We cannot just clear all of m->dirty here as the 4119 * buffer cache buffers may use a DEV_BSIZE'd aligned 4120 * block size, or have an odd size (e.g. NFS at file EOF). 4121 * The putpages code can clear m->dirty to 0. 4122 * 4123 * If a VOP_WRITE generates a buffer cache buffer which 4124 * covers the same space as mapped writable pages the 4125 * buffer flush might not be able to clear all the dirty 4126 * bits and still require a putpages from the VM system 4127 * to finish it off. 4128 */ 4129 vm_page_set_validclean(m, soff & PAGE_MASK, eoff - soff); 4130 } 4131 4132 /* 4133 * Similar to vfs_clean_one_page() but sets the bits to valid and dirty. 4134 * The page data is assumed to be valid (there is no zeroing here). 4135 */ 4136 static void 4137 vfs_dirty_one_page(struct buf *bp, int pageno, vm_page_t m) 4138 { 4139 int bcount; 4140 int xoff; 4141 int soff; 4142 int eoff; 4143 4144 /* 4145 * Calculate offset range within the page but relative to buffer's 4146 * loffset. loffset might be offset into the first page. 4147 */ 4148 xoff = (int)bp->b_loffset & PAGE_MASK; /* loffset offset into pg 0 */ 4149 bcount = bp->b_bcount + xoff; /* offset adjusted */ 4150 4151 if (pageno == 0) { 4152 soff = xoff; 4153 eoff = PAGE_SIZE; 4154 } else { 4155 soff = (pageno << PAGE_SHIFT); 4156 eoff = soff + PAGE_SIZE; 4157 } 4158 if (eoff > bcount) 4159 eoff = bcount; 4160 if (soff >= eoff) 4161 return; 4162 vm_page_set_validdirty(m, soff & PAGE_MASK, eoff - soff); 4163 } 4164 4165 /* 4166 * vfs_bio_clrbuf: 4167 * 4168 * Clear a buffer. This routine essentially fakes an I/O, so we need 4169 * to clear B_ERROR and B_INVAL. 4170 * 4171 * Note that while we only theoretically need to clear through b_bcount, 4172 * we go ahead and clear through b_bufsize. 4173 */ 4174 4175 void 4176 vfs_bio_clrbuf(struct buf *bp) 4177 { 4178 int i, mask = 0; 4179 caddr_t sa, ea; 4180 if ((bp->b_flags & (B_VMIO | B_MALLOC)) == B_VMIO) { 4181 bp->b_flags &= ~(B_INVAL | B_EINTR | B_ERROR); 4182 if ((bp->b_xio.xio_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 4183 (bp->b_loffset & PAGE_MASK) == 0) { 4184 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 4185 if ((bp->b_xio.xio_pages[0]->valid & mask) == mask) { 4186 bp->b_resid = 0; 4187 return; 4188 } 4189 if (((bp->b_xio.xio_pages[0]->flags & PG_ZERO) == 0) && 4190 ((bp->b_xio.xio_pages[0]->valid & mask) == 0)) { 4191 bzero(bp->b_data, bp->b_bufsize); 4192 bp->b_xio.xio_pages[0]->valid |= mask; 4193 bp->b_resid = 0; 4194 return; 4195 } 4196 } 4197 sa = bp->b_data; 4198 for(i=0;i<bp->b_xio.xio_npages;i++,sa=ea) { 4199 int j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; 4200 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); 4201 ea = (caddr_t)(vm_offset_t)ulmin( 4202 (u_long)(vm_offset_t)ea, 4203 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); 4204 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 4205 if ((bp->b_xio.xio_pages[i]->valid & mask) == mask) 4206 continue; 4207 if ((bp->b_xio.xio_pages[i]->valid & mask) == 0) { 4208 if ((bp->b_xio.xio_pages[i]->flags & PG_ZERO) == 0) { 4209 bzero(sa, ea - sa); 4210 } 4211 } else { 4212 for (; sa < ea; sa += DEV_BSIZE, j++) { 4213 if (((bp->b_xio.xio_pages[i]->flags & PG_ZERO) == 0) && 4214 (bp->b_xio.xio_pages[i]->valid & (1<<j)) == 0) 4215 bzero(sa, DEV_BSIZE); 4216 } 4217 } 4218 bp->b_xio.xio_pages[i]->valid |= mask; 4219 vm_page_flag_clear(bp->b_xio.xio_pages[i], PG_ZERO); 4220 } 4221 bp->b_resid = 0; 4222 } else { 4223 clrbuf(bp); 4224 } 4225 } 4226 4227 /* 4228 * vm_hold_load_pages: 4229 * 4230 * Load pages into the buffer's address space. The pages are 4231 * allocated from the kernel object in order to reduce interference 4232 * with the any VM paging I/O activity. The range of loaded 4233 * pages will be wired. 4234 * 4235 * If a page cannot be allocated, the 'pagedaemon' is woken up to 4236 * retrieve the full range (to - from) of pages. 4237 * 4238 */ 4239 void 4240 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4241 { 4242 vm_offset_t pg; 4243 vm_page_t p; 4244 int index; 4245 4246 to = round_page(to); 4247 from = round_page(from); 4248 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4249 4250 pg = from; 4251 while (pg < to) { 4252 /* 4253 * Note: must allocate system pages since blocking here 4254 * could intefere with paging I/O, no matter which 4255 * process we are. 4256 */ 4257 p = bio_page_alloc(&kernel_object, pg >> PAGE_SHIFT, 4258 (vm_pindex_t)((to - pg) >> PAGE_SHIFT)); 4259 if (p) { 4260 vm_page_wire(p); 4261 p->valid = VM_PAGE_BITS_ALL; 4262 vm_page_flag_clear(p, PG_ZERO); 4263 pmap_kenter(pg, VM_PAGE_TO_PHYS(p)); 4264 bp->b_xio.xio_pages[index] = p; 4265 vm_page_wakeup(p); 4266 4267 pg += PAGE_SIZE; 4268 ++index; 4269 } 4270 } 4271 bp->b_xio.xio_npages = index; 4272 } 4273 4274 /* 4275 * Allocate pages for a buffer cache buffer. 4276 * 4277 * Under extremely severe memory conditions even allocating out of the 4278 * system reserve can fail. If this occurs we must allocate out of the 4279 * interrupt reserve to avoid a deadlock with the pageout daemon. 4280 * 4281 * The pageout daemon can run (putpages -> VOP_WRITE -> getblk -> allocbuf). 4282 * If the buffer cache's vm_page_alloc() fails a vm_wait() can deadlock 4283 * against the pageout daemon if pages are not freed from other sources. 4284 */ 4285 static 4286 vm_page_t 4287 bio_page_alloc(vm_object_t obj, vm_pindex_t pg, int deficit) 4288 { 4289 vm_page_t p; 4290 4291 /* 4292 * Try a normal allocation, allow use of system reserve. 4293 */ 4294 p = vm_page_alloc(obj, pg, VM_ALLOC_NORMAL | VM_ALLOC_SYSTEM); 4295 if (p) 4296 return(p); 4297 4298 /* 4299 * The normal allocation failed and we clearly have a page 4300 * deficit. Try to reclaim some clean VM pages directly 4301 * from the buffer cache. 4302 */ 4303 vm_pageout_deficit += deficit; 4304 recoverbufpages(); 4305 4306 /* 4307 * We may have blocked, the caller will know what to do if the 4308 * page now exists. 4309 */ 4310 if (vm_page_lookup(obj, pg)) 4311 return(NULL); 4312 4313 /* 4314 * Allocate and allow use of the interrupt reserve. 4315 * 4316 * If after all that we still can't allocate a VM page we are 4317 * in real trouble, but we slog on anyway hoping that the system 4318 * won't deadlock. 4319 */ 4320 p = vm_page_alloc(obj, pg, VM_ALLOC_NORMAL | VM_ALLOC_SYSTEM | 4321 VM_ALLOC_INTERRUPT); 4322 if (p) { 4323 if (vm_page_count_severe()) { 4324 kprintf("bio_page_alloc: WARNING emergency page " 4325 "allocation\n"); 4326 vm_wait(hz / 20); 4327 } 4328 } else { 4329 kprintf("bio_page_alloc: WARNING emergency page " 4330 "allocation failed\n"); 4331 vm_wait(hz * 5); 4332 } 4333 return(p); 4334 } 4335 4336 /* 4337 * vm_hold_free_pages: 4338 * 4339 * Return pages associated with the buffer back to the VM system. 4340 * 4341 * The range of pages underlying the buffer's address space will 4342 * be unmapped and un-wired. 4343 */ 4344 void 4345 vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4346 { 4347 vm_offset_t pg; 4348 vm_page_t p; 4349 int index, newnpages; 4350 4351 from = round_page(from); 4352 to = round_page(to); 4353 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4354 4355 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 4356 p = bp->b_xio.xio_pages[index]; 4357 if (p && (index < bp->b_xio.xio_npages)) { 4358 if (p->busy) { 4359 kprintf("vm_hold_free_pages: doffset: %lld, " 4360 "loffset: %lld\n", 4361 (long long)bp->b_bio2.bio_offset, 4362 (long long)bp->b_loffset); 4363 } 4364 bp->b_xio.xio_pages[index] = NULL; 4365 pmap_kremove(pg); 4366 vm_page_busy(p); 4367 vm_page_unwire(p, 0); 4368 vm_page_free(p); 4369 } 4370 } 4371 bp->b_xio.xio_npages = newnpages; 4372 } 4373 4374 /* 4375 * vmapbuf: 4376 * 4377 * Map a user buffer into KVM via a pbuf. On return the buffer's 4378 * b_data, b_bufsize, and b_bcount will be set, and its XIO page array 4379 * initialized. 4380 */ 4381 int 4382 vmapbuf(struct buf *bp, caddr_t udata, int bytes) 4383 { 4384 caddr_t addr; 4385 vm_offset_t va; 4386 vm_page_t m; 4387 int vmprot; 4388 int error; 4389 int pidx; 4390 int i; 4391 4392 /* 4393 * bp had better have a command and it better be a pbuf. 4394 */ 4395 KKASSERT(bp->b_cmd != BUF_CMD_DONE); 4396 KKASSERT(bp->b_flags & B_PAGING); 4397 4398 if (bytes < 0) 4399 return (-1); 4400 4401 /* 4402 * Map the user data into KVM. Mappings have to be page-aligned. 4403 */ 4404 addr = (caddr_t)trunc_page((vm_offset_t)udata); 4405 pidx = 0; 4406 4407 vmprot = VM_PROT_READ; 4408 if (bp->b_cmd == BUF_CMD_READ) 4409 vmprot |= VM_PROT_WRITE; 4410 4411 while (addr < udata + bytes) { 4412 /* 4413 * Do the vm_fault if needed; do the copy-on-write thing 4414 * when reading stuff off device into memory. 4415 * 4416 * vm_fault_page*() returns a held VM page. 4417 */ 4418 va = (addr >= udata) ? (vm_offset_t)addr : (vm_offset_t)udata; 4419 va = trunc_page(va); 4420 4421 m = vm_fault_page_quick(va, vmprot, &error); 4422 if (m == NULL) { 4423 for (i = 0; i < pidx; ++i) { 4424 vm_page_unhold(bp->b_xio.xio_pages[i]); 4425 bp->b_xio.xio_pages[i] = NULL; 4426 } 4427 return(-1); 4428 } 4429 bp->b_xio.xio_pages[pidx] = m; 4430 addr += PAGE_SIZE; 4431 ++pidx; 4432 } 4433 4434 /* 4435 * Map the page array and set the buffer fields to point to 4436 * the mapped data buffer. 4437 */ 4438 if (pidx > btoc(MAXPHYS)) 4439 panic("vmapbuf: mapped more than MAXPHYS"); 4440 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_xio.xio_pages, pidx); 4441 4442 bp->b_xio.xio_npages = pidx; 4443 bp->b_data = bp->b_kvabase + ((int)(intptr_t)udata & PAGE_MASK); 4444 bp->b_bcount = bytes; 4445 bp->b_bufsize = bytes; 4446 return(0); 4447 } 4448 4449 /* 4450 * vunmapbuf: 4451 * 4452 * Free the io map PTEs associated with this IO operation. 4453 * We also invalidate the TLB entries and restore the original b_addr. 4454 */ 4455 void 4456 vunmapbuf(struct buf *bp) 4457 { 4458 int pidx; 4459 int npages; 4460 4461 KKASSERT(bp->b_flags & B_PAGING); 4462 4463 npages = bp->b_xio.xio_npages; 4464 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 4465 for (pidx = 0; pidx < npages; ++pidx) { 4466 vm_page_unhold(bp->b_xio.xio_pages[pidx]); 4467 bp->b_xio.xio_pages[pidx] = NULL; 4468 } 4469 bp->b_xio.xio_npages = 0; 4470 bp->b_data = bp->b_kvabase; 4471 } 4472 4473 /* 4474 * Scan all buffers in the system and issue the callback. 4475 */ 4476 int 4477 scan_all_buffers(int (*callback)(struct buf *, void *), void *info) 4478 { 4479 int count = 0; 4480 int error; 4481 int n; 4482 4483 for (n = 0; n < nbuf; ++n) { 4484 if ((error = callback(&buf[n], info)) < 0) { 4485 count = error; 4486 break; 4487 } 4488 count += error; 4489 } 4490 return (count); 4491 } 4492 4493 /* 4494 * print out statistics from the current status of the buffer pool 4495 * this can be toggeled by the system control option debug.syncprt 4496 */ 4497 #ifdef DEBUG 4498 void 4499 vfs_bufstats(void) 4500 { 4501 int i, j, count; 4502 struct buf *bp; 4503 struct bqueues *dp; 4504 int counts[(MAXBSIZE / PAGE_SIZE) + 1]; 4505 static char *bname[3] = { "LOCKED", "LRU", "AGE" }; 4506 4507 for (dp = bufqueues, i = 0; dp < &bufqueues[3]; dp++, i++) { 4508 count = 0; 4509 for (j = 0; j <= MAXBSIZE/PAGE_SIZE; j++) 4510 counts[j] = 0; 4511 crit_enter(); 4512 TAILQ_FOREACH(bp, dp, b_freelist) { 4513 counts[bp->b_bufsize/PAGE_SIZE]++; 4514 count++; 4515 } 4516 crit_exit(); 4517 kprintf("%s: total-%d", bname[i], count); 4518 for (j = 0; j <= MAXBSIZE/PAGE_SIZE; j++) 4519 if (counts[j] != 0) 4520 kprintf(", %d-%d", j * PAGE_SIZE, counts[j]); 4521 kprintf("\n"); 4522 } 4523 } 4524 #endif 4525 4526 #ifdef DDB 4527 4528 DB_SHOW_COMMAND(buffer, db_show_buffer) 4529 { 4530 /* get args */ 4531 struct buf *bp = (struct buf *)addr; 4532 4533 if (!have_addr) { 4534 db_printf("usage: show buffer <addr>\n"); 4535 return; 4536 } 4537 4538 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS); 4539 db_printf("b_cmd = %d\n", bp->b_cmd); 4540 db_printf("b_error = %d, b_bufsize = %d, b_bcount = %d, " 4541 "b_resid = %d\n, b_data = %p, " 4542 "bio_offset(disk) = %lld, bio_offset(phys) = %lld\n", 4543 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 4544 bp->b_data, 4545 (long long)bp->b_bio2.bio_offset, 4546 (long long)(bp->b_bio2.bio_next ? 4547 bp->b_bio2.bio_next->bio_offset : (off_t)-1)); 4548 if (bp->b_xio.xio_npages) { 4549 int i; 4550 db_printf("b_xio.xio_npages = %d, pages(OBJ, IDX, PA): ", 4551 bp->b_xio.xio_npages); 4552 for (i = 0; i < bp->b_xio.xio_npages; i++) { 4553 vm_page_t m; 4554 m = bp->b_xio.xio_pages[i]; 4555 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 4556 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 4557 if ((i + 1) < bp->b_xio.xio_npages) 4558 db_printf(","); 4559 } 4560 db_printf("\n"); 4561 } 4562 } 4563 #endif /* DDB */ 4564