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/dsched.h> 48 #include <sys/proc.h> 49 #include <vm/vm.h> 50 #include <vm/vm_param.h> 51 #include <vm/vm_kern.h> 52 #include <vm/vm_pageout.h> 53 #include <vm/vm_page.h> 54 #include <vm/vm_object.h> 55 #include <vm/vm_extern.h> 56 #include <vm/vm_map.h> 57 #include <vm/vm_pager.h> 58 #include <vm/swap_pager.h> 59 60 #include <sys/buf2.h> 61 #include <sys/thread2.h> 62 #include <sys/spinlock2.h> 63 #include <sys/mplock2.h> 64 #include <vm/vm_page2.h> 65 66 #include "opt_ddb.h" 67 #ifdef DDB 68 #include <ddb/ddb.h> 69 #endif 70 71 /* 72 * Buffer queues. 73 */ 74 enum bufq_type { 75 BQUEUE_NONE, /* not on any queue */ 76 BQUEUE_LOCKED, /* locked buffers */ 77 BQUEUE_CLEAN, /* non-B_DELWRI buffers */ 78 BQUEUE_DIRTY, /* B_DELWRI buffers */ 79 BQUEUE_DIRTY_HW, /* B_DELWRI buffers - heavy weight */ 80 BQUEUE_EMPTYKVA, /* empty buffer headers with KVA assignment */ 81 BQUEUE_EMPTY, /* empty buffer headers */ 82 83 BUFFER_QUEUES /* number of buffer queues */ 84 }; 85 86 typedef enum bufq_type bufq_type_t; 87 88 #define BD_WAKE_SIZE 16384 89 #define BD_WAKE_MASK (BD_WAKE_SIZE - 1) 90 91 TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES]; 92 struct spinlock bufspin = SPINLOCK_INITIALIZER(&bufspin); 93 94 static MALLOC_DEFINE(M_BIOBUF, "BIO buffer", "BIO buffer"); 95 96 struct buf *buf; /* buffer header pool */ 97 98 static void vfs_clean_pages(struct buf *bp); 99 static void vfs_clean_one_page(struct buf *bp, int pageno, vm_page_t m); 100 static void vfs_dirty_one_page(struct buf *bp, int pageno, vm_page_t m); 101 static void vfs_vmio_release(struct buf *bp); 102 static int flushbufqueues(bufq_type_t q); 103 static vm_page_t bio_page_alloc(vm_object_t obj, vm_pindex_t pg, int deficit); 104 105 static void bd_signal(int totalspace); 106 static void buf_daemon(void); 107 static void buf_daemon_hw(void); 108 109 /* 110 * bogus page -- for I/O to/from partially complete buffers 111 * this is a temporary solution to the problem, but it is not 112 * really that bad. it would be better to split the buffer 113 * for input in the case of buffers partially already in memory, 114 * but the code is intricate enough already. 115 */ 116 vm_page_t bogus_page; 117 118 /* 119 * These are all static, but make the ones we export globals so we do 120 * not need to use compiler magic. 121 */ 122 int bufspace, maxbufspace, 123 bufmallocspace, maxbufmallocspace, lobufspace, hibufspace; 124 static int bufreusecnt, bufdefragcnt, buffreekvacnt; 125 static int lorunningspace, hirunningspace, runningbufreq; 126 int dirtybufspace, dirtybufspacehw, lodirtybufspace, hidirtybufspace; 127 int dirtybufcount, dirtybufcounthw; 128 int runningbufspace, runningbufcount; 129 static int getnewbufcalls; 130 static int getnewbufrestarts; 131 static int recoverbufcalls; 132 static int needsbuffer; /* locked by needsbuffer_spin */ 133 static int bd_request; /* locked by needsbuffer_spin */ 134 static int bd_request_hw; /* locked by needsbuffer_spin */ 135 static u_int bd_wake_ary[BD_WAKE_SIZE]; 136 static u_int bd_wake_index; 137 static u_int vm_cycle_point = 40; /* 23-36 will migrate more act->inact */ 138 static struct spinlock needsbuffer_spin; 139 static int debug_commit; 140 141 static struct thread *bufdaemon_td; 142 static struct thread *bufdaemonhw_td; 143 144 145 /* 146 * Sysctls for operational control of the buffer cache. 147 */ 148 SYSCTL_INT(_vfs, OID_AUTO, lodirtybufspace, CTLFLAG_RW, &lodirtybufspace, 0, 149 "Number of dirty buffers to flush before bufdaemon becomes inactive"); 150 SYSCTL_INT(_vfs, OID_AUTO, hidirtybufspace, CTLFLAG_RW, &hidirtybufspace, 0, 151 "High watermark used to trigger explicit flushing of dirty buffers"); 152 SYSCTL_INT(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0, 153 "Minimum amount of buffer space required for active I/O"); 154 SYSCTL_INT(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0, 155 "Maximum amount of buffer space to usable for active I/O"); 156 SYSCTL_UINT(_vfs, OID_AUTO, vm_cycle_point, CTLFLAG_RW, &vm_cycle_point, 0, 157 "Recycle pages to active or inactive queue transition pt 0-64"); 158 /* 159 * Sysctls determining current state of the buffer cache. 160 */ 161 SYSCTL_INT(_vfs, OID_AUTO, nbuf, CTLFLAG_RD, &nbuf, 0, 162 "Total number of buffers in buffer cache"); 163 SYSCTL_INT(_vfs, OID_AUTO, dirtybufspace, CTLFLAG_RD, &dirtybufspace, 0, 164 "Pending bytes of dirty buffers (all)"); 165 SYSCTL_INT(_vfs, OID_AUTO, dirtybufspacehw, CTLFLAG_RD, &dirtybufspacehw, 0, 166 "Pending bytes of dirty buffers (heavy weight)"); 167 SYSCTL_INT(_vfs, OID_AUTO, dirtybufcount, CTLFLAG_RD, &dirtybufcount, 0, 168 "Pending number of dirty buffers"); 169 SYSCTL_INT(_vfs, OID_AUTO, dirtybufcounthw, CTLFLAG_RD, &dirtybufcounthw, 0, 170 "Pending number of dirty buffers (heavy weight)"); 171 SYSCTL_INT(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 172 "I/O bytes currently in progress due to asynchronous writes"); 173 SYSCTL_INT(_vfs, OID_AUTO, runningbufcount, CTLFLAG_RD, &runningbufcount, 0, 174 "I/O buffers currently in progress due to asynchronous writes"); 175 SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0, 176 "Hard limit on maximum amount of memory usable for buffer space"); 177 SYSCTL_INT(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0, 178 "Soft limit on maximum amount of memory usable for buffer space"); 179 SYSCTL_INT(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0, 180 "Minimum amount of memory to reserve for system buffer space"); 181 SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, 182 "Amount of memory available for buffers"); 183 SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RD, &maxbufmallocspace, 184 0, "Maximum amount of memory reserved for buffers using malloc"); 185 SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 186 "Amount of memory left for buffers using malloc-scheme"); 187 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RD, &getnewbufcalls, 0, 188 "New buffer header acquisition requests"); 189 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RD, &getnewbufrestarts, 190 0, "New buffer header acquisition restarts"); 191 SYSCTL_INT(_vfs, OID_AUTO, recoverbufcalls, CTLFLAG_RD, &recoverbufcalls, 0, 192 "Recover VM space in an emergency"); 193 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RD, &bufdefragcnt, 0, 194 "Buffer acquisition restarts due to fragmented buffer map"); 195 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RD, &buffreekvacnt, 0, 196 "Amount of time KVA space was deallocated in an arbitrary buffer"); 197 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RD, &bufreusecnt, 0, 198 "Amount of time buffer re-use operations were successful"); 199 SYSCTL_INT(_vfs, OID_AUTO, debug_commit, CTLFLAG_RW, &debug_commit, 0, ""); 200 SYSCTL_INT(_debug_sizeof, OID_AUTO, buf, CTLFLAG_RD, 0, sizeof(struct buf), 201 "sizeof(struct buf)"); 202 203 char *buf_wmesg = BUF_WMESG; 204 205 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 206 #define VFS_BIO_NEED_UNUSED02 0x02 207 #define VFS_BIO_NEED_UNUSED04 0x04 208 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 209 210 /* 211 * bufspacewakeup: 212 * 213 * Called when buffer space is potentially available for recovery. 214 * getnewbuf() will block on this flag when it is unable to free 215 * sufficient buffer space. Buffer space becomes recoverable when 216 * bp's get placed back in the queues. 217 */ 218 219 static __inline void 220 bufspacewakeup(void) 221 { 222 /* 223 * If someone is waiting for BUF space, wake them up. Even 224 * though we haven't freed the kva space yet, the waiting 225 * process will be able to now. 226 */ 227 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) { 228 spin_lock_wr(&needsbuffer_spin); 229 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE; 230 spin_unlock_wr(&needsbuffer_spin); 231 wakeup(&needsbuffer); 232 } 233 } 234 235 /* 236 * runningbufwakeup: 237 * 238 * Accounting for I/O in progress. 239 * 240 */ 241 static __inline void 242 runningbufwakeup(struct buf *bp) 243 { 244 int totalspace; 245 int limit; 246 247 if ((totalspace = bp->b_runningbufspace) != 0) { 248 atomic_subtract_int(&runningbufspace, totalspace); 249 atomic_subtract_int(&runningbufcount, 1); 250 bp->b_runningbufspace = 0; 251 252 /* 253 * see waitrunningbufspace() for limit test. 254 */ 255 limit = hirunningspace * 2 / 3; 256 if (runningbufreq && runningbufspace <= limit) { 257 runningbufreq = 0; 258 wakeup(&runningbufreq); 259 } 260 bd_signal(totalspace); 261 } 262 } 263 264 /* 265 * bufcountwakeup: 266 * 267 * Called when a buffer has been added to one of the free queues to 268 * account for the buffer and to wakeup anyone waiting for free buffers. 269 * This typically occurs when large amounts of metadata are being handled 270 * by the buffer cache ( else buffer space runs out first, usually ). 271 * 272 * MPSAFE 273 */ 274 static __inline void 275 bufcountwakeup(void) 276 { 277 if (needsbuffer) { 278 spin_lock_wr(&needsbuffer_spin); 279 needsbuffer &= ~VFS_BIO_NEED_ANY; 280 spin_unlock_wr(&needsbuffer_spin); 281 wakeup(&needsbuffer); 282 } 283 } 284 285 /* 286 * waitrunningbufspace() 287 * 288 * Wait for the amount of running I/O to drop to hirunningspace * 2 / 3. 289 * This is the point where write bursting stops so we don't want to wait 290 * for the running amount to drop below it (at least if we still want bioq 291 * to burst writes). 292 * 293 * The caller may be using this function to block in a tight loop, we 294 * must block while runningbufspace is greater then or equal to 295 * hirunningspace * 2 / 3. 296 * 297 * And even with that it may not be enough, due to the presence of 298 * B_LOCKED dirty buffers, so also wait for at least one running buffer 299 * to complete. 300 */ 301 static __inline void 302 waitrunningbufspace(void) 303 { 304 int limit = hirunningspace * 2 / 3; 305 306 crit_enter(); 307 if (runningbufspace > limit) { 308 while (runningbufspace > limit) { 309 ++runningbufreq; 310 tsleep(&runningbufreq, 0, "wdrn1", 0); 311 } 312 } else if (runningbufspace) { 313 ++runningbufreq; 314 tsleep(&runningbufreq, 0, "wdrn2", 1); 315 } 316 crit_exit(); 317 } 318 319 /* 320 * buf_dirty_count_severe: 321 * 322 * Return true if we have too many dirty buffers. 323 */ 324 int 325 buf_dirty_count_severe(void) 326 { 327 return (runningbufspace + dirtybufspace >= hidirtybufspace || 328 dirtybufcount >= nbuf / 2); 329 } 330 331 /* 332 * Return true if the amount of running I/O is severe and BIOQ should 333 * start bursting. 334 */ 335 int 336 buf_runningbufspace_severe(void) 337 { 338 return (runningbufspace >= hirunningspace * 2 / 3); 339 } 340 341 /* 342 * vfs_buf_test_cache: 343 * 344 * Called when a buffer is extended. This function clears the B_CACHE 345 * bit if the newly extended portion of the buffer does not contain 346 * valid data. 347 * 348 * NOTE! Dirty VM pages are not processed into dirty (B_DELWRI) buffer 349 * cache buffers. The VM pages remain dirty, as someone had mmap()'d 350 * them while a clean buffer was present. 351 */ 352 static __inline__ 353 void 354 vfs_buf_test_cache(struct buf *bp, 355 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 356 vm_page_t m) 357 { 358 if (bp->b_flags & B_CACHE) { 359 int base = (foff + off) & PAGE_MASK; 360 if (vm_page_is_valid(m, base, size) == 0) 361 bp->b_flags &= ~B_CACHE; 362 } 363 } 364 365 /* 366 * bd_speedup() 367 * 368 * Spank the buf_daemon[_hw] if the total dirty buffer space exceeds the 369 * low water mark. 370 * 371 * MPSAFE 372 */ 373 static __inline__ 374 void 375 bd_speedup(void) 376 { 377 if (dirtybufspace < lodirtybufspace && dirtybufcount < nbuf / 2) 378 return; 379 380 if (bd_request == 0 && 381 (dirtybufspace - dirtybufspacehw > lodirtybufspace / 2 || 382 dirtybufcount - dirtybufcounthw >= nbuf / 2)) { 383 spin_lock_wr(&needsbuffer_spin); 384 bd_request = 1; 385 spin_unlock_wr(&needsbuffer_spin); 386 wakeup(&bd_request); 387 } 388 if (bd_request_hw == 0 && 389 (dirtybufspacehw > lodirtybufspace / 2 || 390 dirtybufcounthw >= nbuf / 2)) { 391 spin_lock_wr(&needsbuffer_spin); 392 bd_request_hw = 1; 393 spin_unlock_wr(&needsbuffer_spin); 394 wakeup(&bd_request_hw); 395 } 396 } 397 398 /* 399 * bd_heatup() 400 * 401 * Get the buf_daemon heated up when the number of running and dirty 402 * buffers exceeds the mid-point. 403 * 404 * Return the total number of dirty bytes past the second mid point 405 * as a measure of how much excess dirty data there is in the system. 406 * 407 * MPSAFE 408 */ 409 int 410 bd_heatup(void) 411 { 412 int mid1; 413 int mid2; 414 int totalspace; 415 416 mid1 = lodirtybufspace + (hidirtybufspace - lodirtybufspace) / 2; 417 418 totalspace = runningbufspace + dirtybufspace; 419 if (totalspace >= mid1 || dirtybufcount >= nbuf / 2) { 420 bd_speedup(); 421 mid2 = mid1 + (hidirtybufspace - mid1) / 2; 422 if (totalspace >= mid2) 423 return(totalspace - mid2); 424 } 425 return(0); 426 } 427 428 /* 429 * bd_wait() 430 * 431 * Wait for the buffer cache to flush (totalspace) bytes worth of 432 * buffers, then return. 433 * 434 * Regardless this function blocks while the number of dirty buffers 435 * exceeds hidirtybufspace. 436 * 437 * MPSAFE 438 */ 439 void 440 bd_wait(int totalspace) 441 { 442 u_int i; 443 int count; 444 445 if (curthread == bufdaemonhw_td || curthread == bufdaemon_td) 446 return; 447 448 while (totalspace > 0) { 449 bd_heatup(); 450 if (totalspace > runningbufspace + dirtybufspace) 451 totalspace = runningbufspace + dirtybufspace; 452 count = totalspace / BKVASIZE; 453 if (count >= BD_WAKE_SIZE) 454 count = BD_WAKE_SIZE - 1; 455 456 spin_lock_wr(&needsbuffer_spin); 457 i = (bd_wake_index + count) & BD_WAKE_MASK; 458 ++bd_wake_ary[i]; 459 tsleep_interlock(&bd_wake_ary[i], 0); 460 spin_unlock_wr(&needsbuffer_spin); 461 tsleep(&bd_wake_ary[i], PINTERLOCKED, "flstik", hz); 462 463 totalspace = runningbufspace + dirtybufspace - hidirtybufspace; 464 } 465 } 466 467 /* 468 * bd_signal() 469 * 470 * This function is called whenever runningbufspace or dirtybufspace 471 * is reduced. Track threads waiting for run+dirty buffer I/O 472 * complete. 473 * 474 * MPSAFE 475 */ 476 static void 477 bd_signal(int totalspace) 478 { 479 u_int i; 480 481 if (totalspace > 0) { 482 if (totalspace > BKVASIZE * BD_WAKE_SIZE) 483 totalspace = BKVASIZE * BD_WAKE_SIZE; 484 spin_lock_wr(&needsbuffer_spin); 485 while (totalspace > 0) { 486 i = bd_wake_index++; 487 i &= BD_WAKE_MASK; 488 if (bd_wake_ary[i]) { 489 bd_wake_ary[i] = 0; 490 spin_unlock_wr(&needsbuffer_spin); 491 wakeup(&bd_wake_ary[i]); 492 spin_lock_wr(&needsbuffer_spin); 493 } 494 totalspace -= BKVASIZE; 495 } 496 spin_unlock_wr(&needsbuffer_spin); 497 } 498 } 499 500 /* 501 * BIO tracking support routines. 502 * 503 * Release a ref on a bio_track. Wakeup requests are atomically released 504 * along with the last reference so bk_active will never wind up set to 505 * only 0x80000000. 506 * 507 * MPSAFE 508 */ 509 static 510 void 511 bio_track_rel(struct bio_track *track) 512 { 513 int active; 514 int desired; 515 516 /* 517 * Shortcut 518 */ 519 active = track->bk_active; 520 if (active == 1 && atomic_cmpset_int(&track->bk_active, 1, 0)) 521 return; 522 523 /* 524 * Full-on. Note that the wait flag is only atomically released on 525 * the 1->0 count transition. 526 * 527 * We check for a negative count transition using bit 30 since bit 31 528 * has a different meaning. 529 */ 530 for (;;) { 531 desired = (active & 0x7FFFFFFF) - 1; 532 if (desired) 533 desired |= active & 0x80000000; 534 if (atomic_cmpset_int(&track->bk_active, active, desired)) { 535 if (desired & 0x40000000) 536 panic("bio_track_rel: bad count: %p\n", track); 537 if (active & 0x80000000) 538 wakeup(track); 539 break; 540 } 541 active = track->bk_active; 542 } 543 } 544 545 /* 546 * Wait for the tracking count to reach 0. 547 * 548 * Use atomic ops such that the wait flag is only set atomically when 549 * bk_active is non-zero. 550 * 551 * MPSAFE 552 */ 553 int 554 bio_track_wait(struct bio_track *track, int slp_flags, int slp_timo) 555 { 556 int active; 557 int desired; 558 int error; 559 560 /* 561 * Shortcut 562 */ 563 if (track->bk_active == 0) 564 return(0); 565 566 /* 567 * Full-on. Note that the wait flag may only be atomically set if 568 * the active count is non-zero. 569 */ 570 error = 0; 571 while ((active = track->bk_active) != 0) { 572 desired = active | 0x80000000; 573 tsleep_interlock(track, slp_flags); 574 if (active == desired || 575 atomic_cmpset_int(&track->bk_active, active, desired)) { 576 error = tsleep(track, slp_flags | PINTERLOCKED, 577 "iowait", slp_timo); 578 if (error) 579 break; 580 } 581 } 582 return (error); 583 } 584 585 /* 586 * bufinit: 587 * 588 * Load time initialisation of the buffer cache, called from machine 589 * dependant initialization code. 590 */ 591 void 592 bufinit(void) 593 { 594 struct buf *bp; 595 vm_offset_t bogus_offset; 596 int i; 597 598 spin_init(&needsbuffer_spin); 599 600 /* next, make a null set of free lists */ 601 for (i = 0; i < BUFFER_QUEUES; i++) 602 TAILQ_INIT(&bufqueues[i]); 603 604 /* finally, initialize each buffer header and stick on empty q */ 605 for (i = 0; i < nbuf; i++) { 606 bp = &buf[i]; 607 bzero(bp, sizeof *bp); 608 bp->b_flags = B_INVAL; /* we're just an empty header */ 609 bp->b_cmd = BUF_CMD_DONE; 610 bp->b_qindex = BQUEUE_EMPTY; 611 initbufbio(bp); 612 xio_init(&bp->b_xio); 613 buf_dep_init(bp); 614 BUF_LOCKINIT(bp); 615 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_EMPTY], bp, b_freelist); 616 } 617 618 /* 619 * maxbufspace is the absolute maximum amount of buffer space we are 620 * allowed to reserve in KVM and in real terms. The absolute maximum 621 * is nominally used by buf_daemon. hibufspace is the nominal maximum 622 * used by most other processes. The differential is required to 623 * ensure that buf_daemon is able to run when other processes might 624 * be blocked waiting for buffer space. 625 * 626 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 627 * this may result in KVM fragmentation which is not handled optimally 628 * by the system. 629 */ 630 maxbufspace = nbuf * BKVASIZE; 631 hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 632 lobufspace = hibufspace - MAXBSIZE; 633 634 lorunningspace = 512 * 1024; 635 /* hirunningspace -- see below */ 636 637 /* 638 * Limit the amount of malloc memory since it is wired permanently 639 * into the kernel space. Even though this is accounted for in 640 * the buffer allocation, we don't want the malloced region to grow 641 * uncontrolled. The malloc scheme improves memory utilization 642 * significantly on average (small) directories. 643 */ 644 maxbufmallocspace = hibufspace / 20; 645 646 /* 647 * Reduce the chance of a deadlock occuring by limiting the number 648 * of delayed-write dirty buffers we allow to stack up. 649 * 650 * We don't want too much actually queued to the device at once 651 * (XXX this needs to be per-mount!), because the buffers will 652 * wind up locked for a very long period of time while the I/O 653 * drains. 654 */ 655 hidirtybufspace = hibufspace / 2; /* dirty + running */ 656 hirunningspace = hibufspace / 16; /* locked & queued to device */ 657 if (hirunningspace < 1024 * 1024) 658 hirunningspace = 1024 * 1024; 659 660 dirtybufspace = 0; 661 dirtybufspacehw = 0; 662 663 lodirtybufspace = hidirtybufspace / 2; 664 665 /* 666 * Maximum number of async ops initiated per buf_daemon loop. This is 667 * somewhat of a hack at the moment, we really need to limit ourselves 668 * based on the number of bytes of I/O in-transit that were initiated 669 * from buf_daemon. 670 */ 671 672 bogus_offset = kmem_alloc_pageable(&kernel_map, PAGE_SIZE); 673 bogus_page = vm_page_alloc(&kernel_object, 674 (bogus_offset >> PAGE_SHIFT), 675 VM_ALLOC_NORMAL); 676 vmstats.v_wire_count++; 677 678 } 679 680 /* 681 * Initialize the embedded bio structures 682 */ 683 void 684 initbufbio(struct buf *bp) 685 { 686 bp->b_bio1.bio_buf = bp; 687 bp->b_bio1.bio_prev = NULL; 688 bp->b_bio1.bio_offset = NOOFFSET; 689 bp->b_bio1.bio_next = &bp->b_bio2; 690 bp->b_bio1.bio_done = NULL; 691 bp->b_bio1.bio_flags = 0; 692 693 bp->b_bio2.bio_buf = bp; 694 bp->b_bio2.bio_prev = &bp->b_bio1; 695 bp->b_bio2.bio_offset = NOOFFSET; 696 bp->b_bio2.bio_next = NULL; 697 bp->b_bio2.bio_done = NULL; 698 bp->b_bio2.bio_flags = 0; 699 } 700 701 /* 702 * Reinitialize the embedded bio structures as well as any additional 703 * translation cache layers. 704 */ 705 void 706 reinitbufbio(struct buf *bp) 707 { 708 struct bio *bio; 709 710 for (bio = &bp->b_bio1; bio; bio = bio->bio_next) { 711 bio->bio_done = NULL; 712 bio->bio_offset = NOOFFSET; 713 } 714 } 715 716 /* 717 * Push another BIO layer onto an existing BIO and return it. The new 718 * BIO layer may already exist, holding cached translation data. 719 */ 720 struct bio * 721 push_bio(struct bio *bio) 722 { 723 struct bio *nbio; 724 725 if ((nbio = bio->bio_next) == NULL) { 726 int index = bio - &bio->bio_buf->b_bio_array[0]; 727 if (index >= NBUF_BIO - 1) { 728 panic("push_bio: too many layers bp %p\n", 729 bio->bio_buf); 730 } 731 nbio = &bio->bio_buf->b_bio_array[index + 1]; 732 bio->bio_next = nbio; 733 nbio->bio_prev = bio; 734 nbio->bio_buf = bio->bio_buf; 735 nbio->bio_offset = NOOFFSET; 736 nbio->bio_done = NULL; 737 nbio->bio_next = NULL; 738 } 739 KKASSERT(nbio->bio_done == NULL); 740 return(nbio); 741 } 742 743 /* 744 * Pop a BIO translation layer, returning the previous layer. The 745 * must have been previously pushed. 746 */ 747 struct bio * 748 pop_bio(struct bio *bio) 749 { 750 return(bio->bio_prev); 751 } 752 753 void 754 clearbiocache(struct bio *bio) 755 { 756 while (bio) { 757 bio->bio_offset = NOOFFSET; 758 bio = bio->bio_next; 759 } 760 } 761 762 /* 763 * bfreekva: 764 * 765 * Free the KVA allocation for buffer 'bp'. 766 * 767 * Must be called from a critical section as this is the only locking for 768 * buffer_map. 769 * 770 * Since this call frees up buffer space, we call bufspacewakeup(). 771 * 772 * MPALMOSTSAFE 773 */ 774 static void 775 bfreekva(struct buf *bp) 776 { 777 int count; 778 779 if (bp->b_kvasize) { 780 get_mplock(); 781 ++buffreekvacnt; 782 count = vm_map_entry_reserve(MAP_RESERVE_COUNT); 783 vm_map_lock(&buffer_map); 784 bufspace -= bp->b_kvasize; 785 vm_map_delete(&buffer_map, 786 (vm_offset_t) bp->b_kvabase, 787 (vm_offset_t) bp->b_kvabase + bp->b_kvasize, 788 &count 789 ); 790 vm_map_unlock(&buffer_map); 791 vm_map_entry_release(count); 792 bp->b_kvasize = 0; 793 bufspacewakeup(); 794 rel_mplock(); 795 } 796 } 797 798 /* 799 * bremfree: 800 * 801 * Remove the buffer from the appropriate free list. 802 */ 803 static __inline void 804 _bremfree(struct buf *bp) 805 { 806 if (bp->b_qindex != BQUEUE_NONE) { 807 KASSERT(BUF_REFCNTNB(bp) == 1, 808 ("bremfree: bp %p not locked",bp)); 809 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 810 bp->b_qindex = BQUEUE_NONE; 811 } else { 812 if (BUF_REFCNTNB(bp) <= 1) 813 panic("bremfree: removing a buffer not on a queue"); 814 } 815 } 816 817 void 818 bremfree(struct buf *bp) 819 { 820 spin_lock_wr(&bufspin); 821 _bremfree(bp); 822 spin_unlock_wr(&bufspin); 823 } 824 825 static void 826 bremfree_locked(struct buf *bp) 827 { 828 _bremfree(bp); 829 } 830 831 /* 832 * bread: 833 * 834 * Get a buffer with the specified data. Look in the cache first. We 835 * must clear B_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 836 * is set, the buffer is valid and we do not have to do anything ( see 837 * getblk() ). 838 * 839 * MPALMOSTSAFE 840 */ 841 int 842 bread(struct vnode *vp, off_t loffset, int size, struct buf **bpp) 843 { 844 struct buf *bp; 845 846 bp = getblk(vp, loffset, size, 0, 0); 847 *bpp = bp; 848 849 /* if not found in cache, do some I/O */ 850 if ((bp->b_flags & B_CACHE) == 0) { 851 get_mplock(); 852 bp->b_flags &= ~(B_ERROR | B_EINTR | B_INVAL); 853 bp->b_cmd = BUF_CMD_READ; 854 bp->b_bio1.bio_done = biodone_sync; 855 bp->b_bio1.bio_flags |= BIO_SYNC; 856 vfs_busy_pages(vp, bp); 857 vn_strategy(vp, &bp->b_bio1); 858 rel_mplock(); 859 return (biowait(&bp->b_bio1, "biord")); 860 } 861 return (0); 862 } 863 864 /* 865 * breadn: 866 * 867 * Operates like bread, but also starts asynchronous I/O on 868 * read-ahead blocks. We must clear B_ERROR and B_INVAL prior 869 * to initiating I/O . If B_CACHE is set, the buffer is valid 870 * and we do not have to do anything. 871 * 872 * MPALMOSTSAFE 873 */ 874 int 875 breadn(struct vnode *vp, off_t loffset, int size, off_t *raoffset, 876 int *rabsize, int cnt, struct buf **bpp) 877 { 878 struct buf *bp, *rabp; 879 int i; 880 int rv = 0, readwait = 0; 881 882 *bpp = bp = getblk(vp, loffset, size, 0, 0); 883 884 /* if not found in cache, do some I/O */ 885 if ((bp->b_flags & B_CACHE) == 0) { 886 get_mplock(); 887 bp->b_flags &= ~(B_ERROR | B_EINTR | B_INVAL); 888 bp->b_cmd = BUF_CMD_READ; 889 bp->b_bio1.bio_done = biodone_sync; 890 bp->b_bio1.bio_flags |= BIO_SYNC; 891 vfs_busy_pages(vp, bp); 892 vn_strategy(vp, &bp->b_bio1); 893 ++readwait; 894 rel_mplock(); 895 } 896 897 for (i = 0; i < cnt; i++, raoffset++, rabsize++) { 898 if (inmem(vp, *raoffset)) 899 continue; 900 rabp = getblk(vp, *raoffset, *rabsize, 0, 0); 901 902 if ((rabp->b_flags & B_CACHE) == 0) { 903 get_mplock(); 904 rabp->b_flags &= ~(B_ERROR | B_EINTR | B_INVAL); 905 rabp->b_cmd = BUF_CMD_READ; 906 vfs_busy_pages(vp, rabp); 907 BUF_KERNPROC(rabp); 908 vn_strategy(vp, &rabp->b_bio1); 909 rel_mplock(); 910 } else { 911 brelse(rabp); 912 } 913 } 914 if (readwait) 915 rv = biowait(&bp->b_bio1, "biord"); 916 return (rv); 917 } 918 919 /* 920 * bwrite: 921 * 922 * Synchronous write, waits for completion. 923 * 924 * Write, release buffer on completion. (Done by iodone 925 * if async). Do not bother writing anything if the buffer 926 * is invalid. 927 * 928 * Note that we set B_CACHE here, indicating that buffer is 929 * fully valid and thus cacheable. This is true even of NFS 930 * now so we set it generally. This could be set either here 931 * or in biodone() since the I/O is synchronous. We put it 932 * here. 933 */ 934 int 935 bwrite(struct buf *bp) 936 { 937 int error; 938 939 if (bp->b_flags & B_INVAL) { 940 brelse(bp); 941 return (0); 942 } 943 if (BUF_REFCNTNB(bp) == 0) 944 panic("bwrite: buffer is not busy???"); 945 946 /* Mark the buffer clean */ 947 bundirty(bp); 948 949 bp->b_flags &= ~(B_ERROR | B_EINTR); 950 bp->b_flags |= B_CACHE; 951 bp->b_cmd = BUF_CMD_WRITE; 952 bp->b_bio1.bio_done = biodone_sync; 953 bp->b_bio1.bio_flags |= BIO_SYNC; 954 vfs_busy_pages(bp->b_vp, bp); 955 956 /* 957 * Normal bwrites pipeline writes. NOTE: b_bufsize is only 958 * valid for vnode-backed buffers. 959 */ 960 bp->b_runningbufspace = bp->b_bufsize; 961 if (bp->b_runningbufspace) { 962 runningbufspace += bp->b_runningbufspace; 963 ++runningbufcount; 964 } 965 966 vn_strategy(bp->b_vp, &bp->b_bio1); 967 error = biowait(&bp->b_bio1, "biows"); 968 brelse(bp); 969 return (error); 970 } 971 972 /* 973 * bawrite: 974 * 975 * Asynchronous write. Start output on a buffer, but do not wait for 976 * it to complete. The buffer is released when the output completes. 977 * 978 * bwrite() ( or the VOP routine anyway ) is responsible for handling 979 * B_INVAL buffers. Not us. 980 */ 981 void 982 bawrite(struct buf *bp) 983 { 984 if (bp->b_flags & B_INVAL) { 985 brelse(bp); 986 return; 987 } 988 if (BUF_REFCNTNB(bp) == 0) 989 panic("bwrite: buffer is not busy???"); 990 991 /* Mark the buffer clean */ 992 bundirty(bp); 993 994 bp->b_flags &= ~(B_ERROR | B_EINTR); 995 bp->b_flags |= B_CACHE; 996 bp->b_cmd = BUF_CMD_WRITE; 997 KKASSERT(bp->b_bio1.bio_done == NULL); 998 vfs_busy_pages(bp->b_vp, bp); 999 1000 /* 1001 * Normal bwrites pipeline writes. NOTE: b_bufsize is only 1002 * valid for vnode-backed buffers. 1003 */ 1004 bp->b_runningbufspace = bp->b_bufsize; 1005 if (bp->b_runningbufspace) { 1006 runningbufspace += bp->b_runningbufspace; 1007 ++runningbufcount; 1008 } 1009 1010 BUF_KERNPROC(bp); 1011 vn_strategy(bp->b_vp, &bp->b_bio1); 1012 } 1013 1014 /* 1015 * bowrite: 1016 * 1017 * Ordered write. Start output on a buffer, and flag it so that the 1018 * device will write it in the order it was queued. The buffer is 1019 * released when the output completes. bwrite() ( or the VOP routine 1020 * anyway ) is responsible for handling B_INVAL buffers. 1021 */ 1022 int 1023 bowrite(struct buf *bp) 1024 { 1025 bp->b_flags |= B_ORDERED; 1026 bawrite(bp); 1027 return (0); 1028 } 1029 1030 /* 1031 * bdwrite: 1032 * 1033 * Delayed write. (Buffer is marked dirty). Do not bother writing 1034 * anything if the buffer is marked invalid. 1035 * 1036 * Note that since the buffer must be completely valid, we can safely 1037 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 1038 * biodone() in order to prevent getblk from writing the buffer 1039 * out synchronously. 1040 */ 1041 void 1042 bdwrite(struct buf *bp) 1043 { 1044 if (BUF_REFCNTNB(bp) == 0) 1045 panic("bdwrite: buffer is not busy"); 1046 1047 if (bp->b_flags & B_INVAL) { 1048 brelse(bp); 1049 return; 1050 } 1051 bdirty(bp); 1052 1053 if (dsched_is_clear_buf_priv(bp)) 1054 dsched_new_buf(bp); 1055 1056 /* 1057 * Set B_CACHE, indicating that the buffer is fully valid. This is 1058 * true even of NFS now. 1059 */ 1060 bp->b_flags |= B_CACHE; 1061 1062 /* 1063 * This bmap keeps the system from needing to do the bmap later, 1064 * perhaps when the system is attempting to do a sync. Since it 1065 * is likely that the indirect block -- or whatever other datastructure 1066 * that the filesystem needs is still in memory now, it is a good 1067 * thing to do this. Note also, that if the pageout daemon is 1068 * requesting a sync -- there might not be enough memory to do 1069 * the bmap then... So, this is important to do. 1070 */ 1071 if (bp->b_bio2.bio_offset == NOOFFSET) { 1072 VOP_BMAP(bp->b_vp, bp->b_loffset, &bp->b_bio2.bio_offset, 1073 NULL, NULL, BUF_CMD_WRITE); 1074 } 1075 1076 /* 1077 * Because the underlying pages may still be mapped and 1078 * writable trying to set the dirty buffer (b_dirtyoff/end) 1079 * range here will be inaccurate. 1080 * 1081 * However, we must still clean the pages to satisfy the 1082 * vnode_pager and pageout daemon, so theythink the pages 1083 * have been "cleaned". What has really occured is that 1084 * they've been earmarked for later writing by the buffer 1085 * cache. 1086 * 1087 * So we get the b_dirtyoff/end update but will not actually 1088 * depend on it (NFS that is) until the pages are busied for 1089 * writing later on. 1090 */ 1091 vfs_clean_pages(bp); 1092 bqrelse(bp); 1093 1094 /* 1095 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 1096 * due to the softdep code. 1097 */ 1098 } 1099 1100 /* 1101 * Fake write - return pages to VM system as dirty, leave the buffer clean. 1102 * This is used by tmpfs. 1103 * 1104 * It is important for any VFS using this routine to NOT use it for 1105 * IO_SYNC or IO_ASYNC operations which occur when the system really 1106 * wants to flush VM pages to backing store. 1107 */ 1108 void 1109 buwrite(struct buf *bp) 1110 { 1111 vm_page_t m; 1112 int i; 1113 1114 /* 1115 * Only works for VMIO buffers. If the buffer is already 1116 * marked for delayed-write we can't avoid the bdwrite(). 1117 */ 1118 if ((bp->b_flags & B_VMIO) == 0 || (bp->b_flags & B_DELWRI)) { 1119 bdwrite(bp); 1120 return; 1121 } 1122 1123 /* 1124 * Set valid & dirty. 1125 */ 1126 for (i = 0; i < bp->b_xio.xio_npages; i++) { 1127 m = bp->b_xio.xio_pages[i]; 1128 vfs_dirty_one_page(bp, i, m); 1129 } 1130 bqrelse(bp); 1131 } 1132 1133 /* 1134 * bdirty: 1135 * 1136 * Turn buffer into delayed write request by marking it B_DELWRI. 1137 * B_RELBUF and B_NOCACHE must be cleared. 1138 * 1139 * We reassign the buffer to itself to properly update it in the 1140 * dirty/clean lists. 1141 * 1142 * Must be called from a critical section. 1143 * The buffer must be on BQUEUE_NONE. 1144 */ 1145 void 1146 bdirty(struct buf *bp) 1147 { 1148 KASSERT(bp->b_qindex == BQUEUE_NONE, ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1149 if (bp->b_flags & B_NOCACHE) { 1150 kprintf("bdirty: clearing B_NOCACHE on buf %p\n", bp); 1151 bp->b_flags &= ~B_NOCACHE; 1152 } 1153 if (bp->b_flags & B_INVAL) { 1154 kprintf("bdirty: warning, dirtying invalid buffer %p\n", bp); 1155 } 1156 bp->b_flags &= ~B_RELBUF; 1157 1158 if ((bp->b_flags & B_DELWRI) == 0) { 1159 bp->b_flags |= B_DELWRI; 1160 reassignbuf(bp); 1161 atomic_add_int(&dirtybufcount, 1); 1162 dirtybufspace += bp->b_bufsize; 1163 if (bp->b_flags & B_HEAVY) { 1164 atomic_add_int(&dirtybufcounthw, 1); 1165 atomic_add_int(&dirtybufspacehw, bp->b_bufsize); 1166 } 1167 bd_heatup(); 1168 } 1169 } 1170 1171 /* 1172 * Set B_HEAVY, indicating that this is a heavy-weight buffer that 1173 * needs to be flushed with a different buf_daemon thread to avoid 1174 * deadlocks. B_HEAVY also imposes restrictions in getnewbuf(). 1175 */ 1176 void 1177 bheavy(struct buf *bp) 1178 { 1179 if ((bp->b_flags & B_HEAVY) == 0) { 1180 bp->b_flags |= B_HEAVY; 1181 if (bp->b_flags & B_DELWRI) { 1182 atomic_add_int(&dirtybufcounthw, 1); 1183 atomic_add_int(&dirtybufspacehw, bp->b_bufsize); 1184 } 1185 } 1186 } 1187 1188 /* 1189 * bundirty: 1190 * 1191 * Clear B_DELWRI for buffer. 1192 * 1193 * Must be called from a critical section. 1194 * 1195 * The buffer is typically on BQUEUE_NONE but there is one case in 1196 * brelse() that calls this function after placing the buffer on 1197 * a different queue. 1198 * 1199 * MPSAFE 1200 */ 1201 void 1202 bundirty(struct buf *bp) 1203 { 1204 if (bp->b_flags & B_DELWRI) { 1205 bp->b_flags &= ~B_DELWRI; 1206 reassignbuf(bp); 1207 atomic_subtract_int(&dirtybufcount, 1); 1208 atomic_subtract_int(&dirtybufspace, bp->b_bufsize); 1209 if (bp->b_flags & B_HEAVY) { 1210 atomic_subtract_int(&dirtybufcounthw, 1); 1211 atomic_subtract_int(&dirtybufspacehw, bp->b_bufsize); 1212 } 1213 bd_signal(bp->b_bufsize); 1214 } 1215 /* 1216 * Since it is now being written, we can clear its deferred write flag. 1217 */ 1218 bp->b_flags &= ~B_DEFERRED; 1219 } 1220 1221 /* 1222 * brelse: 1223 * 1224 * Release a busy buffer and, if requested, free its resources. The 1225 * buffer will be stashed in the appropriate bufqueue[] allowing it 1226 * to be accessed later as a cache entity or reused for other purposes. 1227 * 1228 * MPALMOSTSAFE 1229 */ 1230 void 1231 brelse(struct buf *bp) 1232 { 1233 #ifdef INVARIANTS 1234 int saved_flags = bp->b_flags; 1235 #endif 1236 1237 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1238 1239 /* 1240 * If B_NOCACHE is set we are being asked to destroy the buffer and 1241 * its backing store. Clear B_DELWRI. 1242 * 1243 * B_NOCACHE is set in two cases: (1) when the caller really wants 1244 * to destroy the buffer and backing store and (2) when the caller 1245 * wants to destroy the buffer and backing store after a write 1246 * completes. 1247 */ 1248 if ((bp->b_flags & (B_NOCACHE|B_DELWRI)) == (B_NOCACHE|B_DELWRI)) { 1249 bundirty(bp); 1250 } 1251 1252 if ((bp->b_flags & (B_INVAL | B_DELWRI)) == B_DELWRI) { 1253 /* 1254 * A re-dirtied buffer is only subject to destruction 1255 * by B_INVAL. B_ERROR and B_NOCACHE are ignored. 1256 */ 1257 /* leave buffer intact */ 1258 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR)) || 1259 (bp->b_bufsize <= 0)) { 1260 /* 1261 * Either a failed read or we were asked to free or not 1262 * cache the buffer. This path is reached with B_DELWRI 1263 * set only if B_INVAL is already set. B_NOCACHE governs 1264 * backing store destruction. 1265 * 1266 * NOTE: HAMMER will set B_LOCKED in buf_deallocate if the 1267 * buffer cannot be immediately freed. 1268 */ 1269 bp->b_flags |= B_INVAL; 1270 if (LIST_FIRST(&bp->b_dep) != NULL) { 1271 get_mplock(); 1272 buf_deallocate(bp); 1273 rel_mplock(); 1274 } 1275 if (bp->b_flags & B_DELWRI) { 1276 atomic_subtract_int(&dirtybufcount, 1); 1277 atomic_subtract_int(&dirtybufspace, bp->b_bufsize); 1278 if (bp->b_flags & B_HEAVY) { 1279 atomic_subtract_int(&dirtybufcounthw, 1); 1280 atomic_subtract_int(&dirtybufspacehw, bp->b_bufsize); 1281 } 1282 bd_signal(bp->b_bufsize); 1283 } 1284 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1285 } 1286 1287 /* 1288 * We must clear B_RELBUF if B_DELWRI or B_LOCKED is set. 1289 * If vfs_vmio_release() is called with either bit set, the 1290 * underlying pages may wind up getting freed causing a previous 1291 * write (bdwrite()) to get 'lost' because pages associated with 1292 * a B_DELWRI bp are marked clean. Pages associated with a 1293 * B_LOCKED buffer may be mapped by the filesystem. 1294 * 1295 * If we want to release the buffer ourselves (rather then the 1296 * originator asking us to release it), give the originator a 1297 * chance to countermand the release by setting B_LOCKED. 1298 * 1299 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1300 * if B_DELWRI is set. 1301 * 1302 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1303 * on pages to return pages to the VM page queues. 1304 */ 1305 if (bp->b_flags & (B_DELWRI | B_LOCKED)) { 1306 bp->b_flags &= ~B_RELBUF; 1307 } else if (vm_page_count_severe()) { 1308 if (LIST_FIRST(&bp->b_dep) != NULL) { 1309 get_mplock(); 1310 buf_deallocate(bp); /* can set B_LOCKED */ 1311 rel_mplock(); 1312 } 1313 if (bp->b_flags & (B_DELWRI | B_LOCKED)) 1314 bp->b_flags &= ~B_RELBUF; 1315 else 1316 bp->b_flags |= B_RELBUF; 1317 } 1318 1319 /* 1320 * Make sure b_cmd is clear. It may have already been cleared by 1321 * biodone(). 1322 * 1323 * At this point destroying the buffer is governed by the B_INVAL 1324 * or B_RELBUF flags. 1325 */ 1326 bp->b_cmd = BUF_CMD_DONE; 1327 dsched_exit_buf(bp); 1328 1329 /* 1330 * VMIO buffer rundown. Make sure the VM page array is restored 1331 * after an I/O may have replaces some of the pages with bogus pages 1332 * in order to not destroy dirty pages in a fill-in read. 1333 * 1334 * Note that due to the code above, if a buffer is marked B_DELWRI 1335 * then the B_RELBUF and B_NOCACHE bits will always be clear. 1336 * B_INVAL may still be set, however. 1337 * 1338 * For clean buffers, B_INVAL or B_RELBUF will destroy the buffer 1339 * but not the backing store. B_NOCACHE will destroy the backing 1340 * store. 1341 * 1342 * Note that dirty NFS buffers contain byte-granular write ranges 1343 * and should not be destroyed w/ B_INVAL even if the backing store 1344 * is left intact. 1345 */ 1346 if (bp->b_flags & B_VMIO) { 1347 /* 1348 * Rundown for VMIO buffers which are not dirty NFS buffers. 1349 */ 1350 int i, j, resid; 1351 vm_page_t m; 1352 off_t foff; 1353 vm_pindex_t poff; 1354 vm_object_t obj; 1355 struct vnode *vp; 1356 1357 vp = bp->b_vp; 1358 1359 /* 1360 * Get the base offset and length of the buffer. Note that 1361 * in the VMIO case if the buffer block size is not 1362 * page-aligned then b_data pointer may not be page-aligned. 1363 * But our b_xio.xio_pages array *IS* page aligned. 1364 * 1365 * block sizes less then DEV_BSIZE (usually 512) are not 1366 * supported due to the page granularity bits (m->valid, 1367 * m->dirty, etc...). 1368 * 1369 * See man buf(9) for more information 1370 */ 1371 1372 resid = bp->b_bufsize; 1373 foff = bp->b_loffset; 1374 1375 get_mplock(); 1376 for (i = 0; i < bp->b_xio.xio_npages; i++) { 1377 m = bp->b_xio.xio_pages[i]; 1378 vm_page_flag_clear(m, PG_ZERO); 1379 /* 1380 * If we hit a bogus page, fixup *all* of them 1381 * now. Note that we left these pages wired 1382 * when we removed them so they had better exist, 1383 * and they cannot be ripped out from under us so 1384 * no critical section protection is necessary. 1385 */ 1386 if (m == bogus_page) { 1387 obj = vp->v_object; 1388 poff = OFF_TO_IDX(bp->b_loffset); 1389 1390 for (j = i; j < bp->b_xio.xio_npages; j++) { 1391 vm_page_t mtmp; 1392 1393 mtmp = bp->b_xio.xio_pages[j]; 1394 if (mtmp == bogus_page) { 1395 mtmp = vm_page_lookup(obj, poff + j); 1396 if (!mtmp) { 1397 panic("brelse: page missing"); 1398 } 1399 bp->b_xio.xio_pages[j] = mtmp; 1400 } 1401 } 1402 1403 if ((bp->b_flags & B_INVAL) == 0) { 1404 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 1405 bp->b_xio.xio_pages, bp->b_xio.xio_npages); 1406 } 1407 m = bp->b_xio.xio_pages[i]; 1408 } 1409 1410 /* 1411 * Invalidate the backing store if B_NOCACHE is set 1412 * (e.g. used with vinvalbuf()). If this is NFS 1413 * we impose a requirement that the block size be 1414 * a multiple of PAGE_SIZE and create a temporary 1415 * hack to basically invalidate the whole page. The 1416 * problem is that NFS uses really odd buffer sizes 1417 * especially when tracking piecemeal writes and 1418 * it also vinvalbuf()'s a lot, which would result 1419 * in only partial page validation and invalidation 1420 * here. If the file page is mmap()'d, however, 1421 * all the valid bits get set so after we invalidate 1422 * here we would end up with weird m->valid values 1423 * like 0xfc. nfs_getpages() can't handle this so 1424 * we clear all the valid bits for the NFS case 1425 * instead of just some of them. 1426 * 1427 * The real bug is the VM system having to set m->valid 1428 * to VM_PAGE_BITS_ALL for faulted-in pages, which 1429 * itself is an artifact of the whole 512-byte 1430 * granular mess that exists to support odd block 1431 * sizes and UFS meta-data block sizes (e.g. 6144). 1432 * A complete rewrite is required. 1433 * 1434 * XXX 1435 */ 1436 if (bp->b_flags & (B_NOCACHE|B_ERROR)) { 1437 int poffset = foff & PAGE_MASK; 1438 int presid; 1439 1440 presid = PAGE_SIZE - poffset; 1441 if (bp->b_vp->v_tag == VT_NFS && 1442 bp->b_vp->v_type == VREG) { 1443 ; /* entire page */ 1444 } else if (presid > resid) { 1445 presid = resid; 1446 } 1447 KASSERT(presid >= 0, ("brelse: extra page")); 1448 vm_page_set_invalid(m, poffset, presid); 1449 1450 /* 1451 * Also make sure any swap cache is removed 1452 * as it is now stale (HAMMER in particular 1453 * uses B_NOCACHE to deal with buffer 1454 * aliasing). 1455 */ 1456 swap_pager_unswapped(m); 1457 } 1458 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1459 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1460 } 1461 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1462 vfs_vmio_release(bp); 1463 rel_mplock(); 1464 } else { 1465 /* 1466 * Rundown for non-VMIO buffers. 1467 */ 1468 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1469 get_mplock(); 1470 if (bp->b_bufsize) 1471 allocbuf(bp, 0); 1472 KKASSERT (LIST_FIRST(&bp->b_dep) == NULL); 1473 if (bp->b_vp) 1474 brelvp(bp); 1475 rel_mplock(); 1476 } 1477 } 1478 1479 if (bp->b_qindex != BQUEUE_NONE) 1480 panic("brelse: free buffer onto another queue???"); 1481 if (BUF_REFCNTNB(bp) > 1) { 1482 /* Temporary panic to verify exclusive locking */ 1483 /* This panic goes away when we allow shared refs */ 1484 panic("brelse: multiple refs"); 1485 /* NOT REACHED */ 1486 return; 1487 } 1488 1489 /* 1490 * Figure out the correct queue to place the cleaned up buffer on. 1491 * Buffers placed in the EMPTY or EMPTYKVA had better already be 1492 * disassociated from their vnode. 1493 */ 1494 spin_lock_wr(&bufspin); 1495 if (bp->b_flags & B_LOCKED) { 1496 /* 1497 * Buffers that are locked are placed in the locked queue 1498 * immediately, regardless of their state. 1499 */ 1500 bp->b_qindex = BQUEUE_LOCKED; 1501 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_LOCKED], bp, b_freelist); 1502 } else if (bp->b_bufsize == 0) { 1503 /* 1504 * Buffers with no memory. Due to conditionals near the top 1505 * of brelse() such buffers should probably already be 1506 * marked B_INVAL and disassociated from their vnode. 1507 */ 1508 bp->b_flags |= B_INVAL; 1509 KASSERT(bp->b_vp == NULL, ("bp1 %p flags %08x/%08x vnode %p unexpectededly still associated!", bp, saved_flags, bp->b_flags, bp->b_vp)); 1510 KKASSERT((bp->b_flags & B_HASHED) == 0); 1511 if (bp->b_kvasize) { 1512 bp->b_qindex = BQUEUE_EMPTYKVA; 1513 } else { 1514 bp->b_qindex = BQUEUE_EMPTY; 1515 } 1516 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1517 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) { 1518 /* 1519 * Buffers with junk contents. Again these buffers had better 1520 * already be disassociated from their vnode. 1521 */ 1522 KASSERT(bp->b_vp == NULL, ("bp2 %p flags %08x/%08x vnode %p unexpectededly still associated!", bp, saved_flags, bp->b_flags, bp->b_vp)); 1523 KKASSERT((bp->b_flags & B_HASHED) == 0); 1524 bp->b_flags |= B_INVAL; 1525 bp->b_qindex = BQUEUE_CLEAN; 1526 TAILQ_INSERT_HEAD(&bufqueues[BQUEUE_CLEAN], bp, b_freelist); 1527 } else { 1528 /* 1529 * Remaining buffers. These buffers are still associated with 1530 * their vnode. 1531 */ 1532 switch(bp->b_flags & (B_DELWRI|B_HEAVY)) { 1533 case B_DELWRI: 1534 bp->b_qindex = BQUEUE_DIRTY; 1535 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_DIRTY], bp, b_freelist); 1536 break; 1537 case B_DELWRI | B_HEAVY: 1538 bp->b_qindex = BQUEUE_DIRTY_HW; 1539 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_DIRTY_HW], bp, 1540 b_freelist); 1541 break; 1542 default: 1543 /* 1544 * NOTE: Buffers are always placed at the end of the 1545 * queue. If B_AGE is not set the buffer will cycle 1546 * through the queue twice. 1547 */ 1548 bp->b_qindex = BQUEUE_CLEAN; 1549 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_CLEAN], bp, b_freelist); 1550 break; 1551 } 1552 } 1553 spin_unlock_wr(&bufspin); 1554 1555 /* 1556 * If B_INVAL, clear B_DELWRI. We've already placed the buffer 1557 * on the correct queue. 1558 */ 1559 if ((bp->b_flags & (B_INVAL|B_DELWRI)) == (B_INVAL|B_DELWRI)) 1560 bundirty(bp); 1561 1562 /* 1563 * The bp is on an appropriate queue unless locked. If it is not 1564 * locked or dirty we can wakeup threads waiting for buffer space. 1565 * 1566 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1567 * if B_INVAL is set ). 1568 */ 1569 if ((bp->b_flags & (B_LOCKED|B_DELWRI)) == 0) 1570 bufcountwakeup(); 1571 1572 /* 1573 * Something we can maybe free or reuse 1574 */ 1575 if (bp->b_bufsize || bp->b_kvasize) 1576 bufspacewakeup(); 1577 1578 /* 1579 * Clean up temporary flags and unlock the buffer. 1580 */ 1581 bp->b_flags &= ~(B_ORDERED | B_NOCACHE | B_RELBUF | B_DIRECT); 1582 BUF_UNLOCK(bp); 1583 } 1584 1585 /* 1586 * bqrelse: 1587 * 1588 * Release a buffer back to the appropriate queue but do not try to free 1589 * it. The buffer is expected to be used again soon. 1590 * 1591 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1592 * biodone() to requeue an async I/O on completion. It is also used when 1593 * known good buffers need to be requeued but we think we may need the data 1594 * again soon. 1595 * 1596 * XXX we should be able to leave the B_RELBUF hint set on completion. 1597 * 1598 * MPSAFE 1599 */ 1600 void 1601 bqrelse(struct buf *bp) 1602 { 1603 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1604 1605 if (bp->b_qindex != BQUEUE_NONE) 1606 panic("bqrelse: free buffer onto another queue???"); 1607 if (BUF_REFCNTNB(bp) > 1) { 1608 /* do not release to free list */ 1609 panic("bqrelse: multiple refs"); 1610 return; 1611 } 1612 1613 buf_act_advance(bp); 1614 1615 spin_lock_wr(&bufspin); 1616 if (bp->b_flags & B_LOCKED) { 1617 /* 1618 * Locked buffers are released to the locked queue. However, 1619 * if the buffer is dirty it will first go into the dirty 1620 * queue and later on after the I/O completes successfully it 1621 * will be released to the locked queue. 1622 */ 1623 bp->b_qindex = BQUEUE_LOCKED; 1624 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_LOCKED], bp, b_freelist); 1625 } else if (bp->b_flags & B_DELWRI) { 1626 bp->b_qindex = (bp->b_flags & B_HEAVY) ? 1627 BQUEUE_DIRTY_HW : BQUEUE_DIRTY; 1628 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1629 } else if (vm_page_count_severe()) { 1630 /* 1631 * We are too low on memory, we have to try to free the 1632 * buffer (most importantly: the wired pages making up its 1633 * backing store) *now*. 1634 */ 1635 spin_unlock_wr(&bufspin); 1636 brelse(bp); 1637 return; 1638 } else { 1639 bp->b_qindex = BQUEUE_CLEAN; 1640 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_CLEAN], bp, b_freelist); 1641 } 1642 spin_unlock_wr(&bufspin); 1643 1644 if ((bp->b_flags & B_LOCKED) == 0 && 1645 ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0)) { 1646 bufcountwakeup(); 1647 } 1648 1649 /* 1650 * Something we can maybe free or reuse. 1651 */ 1652 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1653 bufspacewakeup(); 1654 1655 /* 1656 * Final cleanup and unlock. Clear bits that are only used while a 1657 * buffer is actively locked. 1658 */ 1659 bp->b_flags &= ~(B_ORDERED | B_NOCACHE | B_RELBUF); 1660 dsched_exit_buf(bp); 1661 BUF_UNLOCK(bp); 1662 } 1663 1664 /* 1665 * vfs_vmio_release: 1666 * 1667 * Return backing pages held by the buffer 'bp' back to the VM system 1668 * if possible. The pages are freed if they are no longer valid or 1669 * attempt to free if it was used for direct I/O otherwise they are 1670 * sent to the page cache. 1671 * 1672 * Pages that were marked busy are left alone and skipped. 1673 * 1674 * The KVA mapping (b_data) for the underlying pages is removed by 1675 * this function. 1676 */ 1677 static void 1678 vfs_vmio_release(struct buf *bp) 1679 { 1680 int i; 1681 vm_page_t m; 1682 1683 lwkt_gettoken(&vm_token); 1684 crit_enter(); 1685 for (i = 0; i < bp->b_xio.xio_npages; i++) { 1686 m = bp->b_xio.xio_pages[i]; 1687 bp->b_xio.xio_pages[i] = NULL; 1688 1689 /* 1690 * The VFS is telling us this is not a meta-data buffer 1691 * even if it is backed by a block device. 1692 */ 1693 if (bp->b_flags & B_NOTMETA) 1694 vm_page_flag_set(m, PG_NOTMETA); 1695 1696 /* 1697 * This is a very important bit of code. We try to track 1698 * VM page use whether the pages are wired into the buffer 1699 * cache or not. While wired into the buffer cache the 1700 * bp tracks the act_count. 1701 * 1702 * We can choose to place unwired pages on the inactive 1703 * queue (0) or active queue (1). If we place too many 1704 * on the active queue the queue will cycle the act_count 1705 * on pages we'd like to keep, just from single-use pages 1706 * (such as when doing a tar-up or file scan). 1707 */ 1708 if (bp->b_act_count < vm_cycle_point) 1709 vm_page_unwire(m, 0); 1710 else 1711 vm_page_unwire(m, 1); 1712 1713 /* 1714 * We don't mess with busy pages, it is 1715 * the responsibility of the process that 1716 * busied the pages to deal with them. 1717 */ 1718 if ((m->flags & PG_BUSY) || (m->busy != 0)) 1719 continue; 1720 1721 if (m->wire_count == 0) { 1722 vm_page_flag_clear(m, PG_ZERO); 1723 /* 1724 * Might as well free the page if we can and it has 1725 * no valid data. We also free the page if the 1726 * buffer was used for direct I/O. 1727 */ 1728 #if 0 1729 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && 1730 m->hold_count == 0) { 1731 vm_page_busy(m); 1732 vm_page_protect(m, VM_PROT_NONE); 1733 vm_page_free(m); 1734 } else 1735 #endif 1736 if (bp->b_flags & B_DIRECT) { 1737 vm_page_try_to_free(m); 1738 } else if (vm_page_count_severe()) { 1739 m->act_count = bp->b_act_count; 1740 vm_page_try_to_cache(m); 1741 } else { 1742 m->act_count = bp->b_act_count; 1743 } 1744 } 1745 } 1746 crit_exit(); 1747 lwkt_reltoken(&vm_token); 1748 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_xio.xio_npages); 1749 if (bp->b_bufsize) { 1750 bufspacewakeup(); 1751 bp->b_bufsize = 0; 1752 } 1753 bp->b_xio.xio_npages = 0; 1754 bp->b_flags &= ~B_VMIO; 1755 KKASSERT (LIST_FIRST(&bp->b_dep) == NULL); 1756 if (bp->b_vp) { 1757 get_mplock(); 1758 brelvp(bp); 1759 rel_mplock(); 1760 } 1761 } 1762 1763 /* 1764 * vfs_bio_awrite: 1765 * 1766 * Implement clustered async writes for clearing out B_DELWRI buffers. 1767 * This is much better then the old way of writing only one buffer at 1768 * a time. Note that we may not be presented with the buffers in the 1769 * correct order, so we search for the cluster in both directions. 1770 * 1771 * The buffer is locked on call. 1772 */ 1773 int 1774 vfs_bio_awrite(struct buf *bp) 1775 { 1776 int i; 1777 int j; 1778 off_t loffset = bp->b_loffset; 1779 struct vnode *vp = bp->b_vp; 1780 int nbytes; 1781 struct buf *bpa; 1782 int nwritten; 1783 int size; 1784 1785 /* 1786 * right now we support clustered writing only to regular files. If 1787 * we find a clusterable block we could be in the middle of a cluster 1788 * rather then at the beginning. 1789 * 1790 * NOTE: b_bio1 contains the logical loffset and is aliased 1791 * to b_loffset. b_bio2 contains the translated block number. 1792 */ 1793 if ((vp->v_type == VREG) && 1794 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1795 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1796 1797 size = vp->v_mount->mnt_stat.f_iosize; 1798 1799 for (i = size; i < MAXPHYS; i += size) { 1800 if ((bpa = findblk(vp, loffset + i, FINDBLK_TEST)) && 1801 BUF_REFCNT(bpa) == 0 && 1802 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == 1803 (B_DELWRI | B_CLUSTEROK)) && 1804 (bpa->b_bufsize == size)) { 1805 if ((bpa->b_bio2.bio_offset == NOOFFSET) || 1806 (bpa->b_bio2.bio_offset != 1807 bp->b_bio2.bio_offset + i)) 1808 break; 1809 } else { 1810 break; 1811 } 1812 } 1813 for (j = size; i + j <= MAXPHYS && j <= loffset; j += size) { 1814 if ((bpa = findblk(vp, loffset - j, FINDBLK_TEST)) && 1815 BUF_REFCNT(bpa) == 0 && 1816 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == 1817 (B_DELWRI | B_CLUSTEROK)) && 1818 (bpa->b_bufsize == size)) { 1819 if ((bpa->b_bio2.bio_offset == NOOFFSET) || 1820 (bpa->b_bio2.bio_offset != 1821 bp->b_bio2.bio_offset - j)) 1822 break; 1823 } else { 1824 break; 1825 } 1826 } 1827 j -= size; 1828 nbytes = (i + j); 1829 1830 /* 1831 * this is a possible cluster write 1832 */ 1833 if (nbytes != size) { 1834 BUF_UNLOCK(bp); 1835 nwritten = cluster_wbuild(vp, size, 1836 loffset - j, nbytes); 1837 return nwritten; 1838 } 1839 } 1840 1841 /* 1842 * default (old) behavior, writing out only one block 1843 * 1844 * XXX returns b_bufsize instead of b_bcount for nwritten? 1845 */ 1846 nwritten = bp->b_bufsize; 1847 bremfree(bp); 1848 bawrite(bp); 1849 1850 return nwritten; 1851 } 1852 1853 /* 1854 * getnewbuf: 1855 * 1856 * Find and initialize a new buffer header, freeing up existing buffers 1857 * in the bufqueues as necessary. The new buffer is returned locked. 1858 * 1859 * Important: B_INVAL is not set. If the caller wishes to throw the 1860 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1861 * 1862 * We block if: 1863 * We have insufficient buffer headers 1864 * We have insufficient buffer space 1865 * buffer_map is too fragmented ( space reservation fails ) 1866 * If we have to flush dirty buffers ( but we try to avoid this ) 1867 * 1868 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1869 * Instead we ask the buf daemon to do it for us. We attempt to 1870 * avoid piecemeal wakeups of the pageout daemon. 1871 * 1872 * MPALMOSTSAFE 1873 */ 1874 static struct buf * 1875 getnewbuf(int blkflags, int slptimeo, int size, int maxsize) 1876 { 1877 struct buf *bp; 1878 struct buf *nbp; 1879 int defrag = 0; 1880 int nqindex; 1881 int slpflags = (blkflags & GETBLK_PCATCH) ? PCATCH : 0; 1882 static int flushingbufs; 1883 1884 /* 1885 * We can't afford to block since we might be holding a vnode lock, 1886 * which may prevent system daemons from running. We deal with 1887 * low-memory situations by proactively returning memory and running 1888 * async I/O rather then sync I/O. 1889 */ 1890 1891 ++getnewbufcalls; 1892 --getnewbufrestarts; 1893 restart: 1894 ++getnewbufrestarts; 1895 1896 /* 1897 * Setup for scan. If we do not have enough free buffers, 1898 * we setup a degenerate case that immediately fails. Note 1899 * that if we are specially marked process, we are allowed to 1900 * dip into our reserves. 1901 * 1902 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 1903 * 1904 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 1905 * However, there are a number of cases (defragging, reusing, ...) 1906 * where we cannot backup. 1907 */ 1908 nqindex = BQUEUE_EMPTYKVA; 1909 spin_lock_wr(&bufspin); 1910 nbp = TAILQ_FIRST(&bufqueues[BQUEUE_EMPTYKVA]); 1911 1912 if (nbp == NULL) { 1913 /* 1914 * If no EMPTYKVA buffers and we are either 1915 * defragging or reusing, locate a CLEAN buffer 1916 * to free or reuse. If bufspace useage is low 1917 * skip this step so we can allocate a new buffer. 1918 */ 1919 if (defrag || bufspace >= lobufspace) { 1920 nqindex = BQUEUE_CLEAN; 1921 nbp = TAILQ_FIRST(&bufqueues[BQUEUE_CLEAN]); 1922 } 1923 1924 /* 1925 * If we could not find or were not allowed to reuse a 1926 * CLEAN buffer, check to see if it is ok to use an EMPTY 1927 * buffer. We can only use an EMPTY buffer if allocating 1928 * its KVA would not otherwise run us out of buffer space. 1929 */ 1930 if (nbp == NULL && defrag == 0 && 1931 bufspace + maxsize < hibufspace) { 1932 nqindex = BQUEUE_EMPTY; 1933 nbp = TAILQ_FIRST(&bufqueues[BQUEUE_EMPTY]); 1934 } 1935 } 1936 1937 /* 1938 * Run scan, possibly freeing data and/or kva mappings on the fly 1939 * depending. 1940 * 1941 * WARNING! bufspin is held! 1942 */ 1943 while ((bp = nbp) != NULL) { 1944 int qindex = nqindex; 1945 1946 nbp = TAILQ_NEXT(bp, b_freelist); 1947 1948 /* 1949 * BQUEUE_CLEAN - B_AGE special case. If not set the bp 1950 * cycles through the queue twice before being selected. 1951 */ 1952 if (qindex == BQUEUE_CLEAN && 1953 (bp->b_flags & B_AGE) == 0 && nbp) { 1954 bp->b_flags |= B_AGE; 1955 TAILQ_REMOVE(&bufqueues[qindex], bp, b_freelist); 1956 TAILQ_INSERT_TAIL(&bufqueues[qindex], bp, b_freelist); 1957 continue; 1958 } 1959 1960 /* 1961 * Calculate next bp ( we can only use it if we do not block 1962 * or do other fancy things ). 1963 */ 1964 if (nbp == NULL) { 1965 switch(qindex) { 1966 case BQUEUE_EMPTY: 1967 nqindex = BQUEUE_EMPTYKVA; 1968 if ((nbp = TAILQ_FIRST(&bufqueues[BQUEUE_EMPTYKVA]))) 1969 break; 1970 /* fall through */ 1971 case BQUEUE_EMPTYKVA: 1972 nqindex = BQUEUE_CLEAN; 1973 if ((nbp = TAILQ_FIRST(&bufqueues[BQUEUE_CLEAN]))) 1974 break; 1975 /* fall through */ 1976 case BQUEUE_CLEAN: 1977 /* 1978 * nbp is NULL. 1979 */ 1980 break; 1981 } 1982 } 1983 1984 /* 1985 * Sanity Checks 1986 */ 1987 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistent queue %d bp %p", qindex, bp)); 1988 1989 /* 1990 * Note: we no longer distinguish between VMIO and non-VMIO 1991 * buffers. 1992 */ 1993 1994 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); 1995 1996 /* 1997 * If we are defragging then we need a buffer with 1998 * b_kvasize != 0. XXX this situation should no longer 1999 * occur, if defrag is non-zero the buffer's b_kvasize 2000 * should also be non-zero at this point. XXX 2001 */ 2002 if (defrag && bp->b_kvasize == 0) { 2003 kprintf("Warning: defrag empty buffer %p\n", bp); 2004 continue; 2005 } 2006 2007 /* 2008 * Start freeing the bp. This is somewhat involved. nbp 2009 * remains valid only for BQUEUE_EMPTY[KVA] bp's. Buffers 2010 * on the clean list must be disassociated from their 2011 * current vnode. Buffers on the empty[kva] lists have 2012 * already been disassociated. 2013 */ 2014 2015 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) { 2016 spin_unlock_wr(&bufspin); 2017 tsleep(&bd_request, 0, "gnbxxx", hz / 100); 2018 goto restart; 2019 } 2020 if (bp->b_qindex != qindex) { 2021 spin_unlock_wr(&bufspin); 2022 kprintf("getnewbuf: warning, BUF_LOCK blocked unexpectedly on buf %p index %d->%d, race corrected\n", bp, qindex, bp->b_qindex); 2023 BUF_UNLOCK(bp); 2024 goto restart; 2025 } 2026 bremfree_locked(bp); 2027 spin_unlock_wr(&bufspin); 2028 2029 /* 2030 * Dependancies must be handled before we disassociate the 2031 * vnode. 2032 * 2033 * NOTE: HAMMER will set B_LOCKED if the buffer cannot 2034 * be immediately disassociated. HAMMER then becomes 2035 * responsible for releasing the buffer. 2036 * 2037 * NOTE: bufspin is UNLOCKED now. 2038 */ 2039 if (LIST_FIRST(&bp->b_dep) != NULL) { 2040 get_mplock(); 2041 buf_deallocate(bp); 2042 rel_mplock(); 2043 if (bp->b_flags & B_LOCKED) { 2044 bqrelse(bp); 2045 goto restart; 2046 } 2047 KKASSERT(LIST_FIRST(&bp->b_dep) == NULL); 2048 } 2049 2050 if (qindex == BQUEUE_CLEAN) { 2051 get_mplock(); 2052 if (bp->b_flags & B_VMIO) { 2053 get_mplock(); 2054 vfs_vmio_release(bp); 2055 rel_mplock(); 2056 } 2057 if (bp->b_vp) 2058 brelvp(bp); 2059 rel_mplock(); 2060 } 2061 2062 /* 2063 * NOTE: nbp is now entirely invalid. We can only restart 2064 * the scan from this point on. 2065 * 2066 * Get the rest of the buffer freed up. b_kva* is still 2067 * valid after this operation. 2068 */ 2069 2070 KASSERT(bp->b_vp == NULL, ("bp3 %p flags %08x vnode %p qindex %d unexpectededly still associated!", bp, bp->b_flags, bp->b_vp, qindex)); 2071 KKASSERT((bp->b_flags & B_HASHED) == 0); 2072 2073 /* 2074 * critical section protection is not required when 2075 * scrapping a buffer's contents because it is already 2076 * wired. 2077 */ 2078 if (bp->b_bufsize) { 2079 get_mplock(); 2080 allocbuf(bp, 0); 2081 rel_mplock(); 2082 } 2083 2084 bp->b_flags = B_BNOCLIP; 2085 bp->b_cmd = BUF_CMD_DONE; 2086 bp->b_vp = NULL; 2087 bp->b_error = 0; 2088 bp->b_resid = 0; 2089 bp->b_bcount = 0; 2090 bp->b_xio.xio_npages = 0; 2091 bp->b_dirtyoff = bp->b_dirtyend = 0; 2092 bp->b_act_count = ACT_INIT; 2093 reinitbufbio(bp); 2094 KKASSERT(LIST_FIRST(&bp->b_dep) == NULL); 2095 buf_dep_init(bp); 2096 if (blkflags & GETBLK_BHEAVY) 2097 bp->b_flags |= B_HEAVY; 2098 2099 /* 2100 * If we are defragging then free the buffer. 2101 */ 2102 if (defrag) { 2103 bp->b_flags |= B_INVAL; 2104 bfreekva(bp); 2105 brelse(bp); 2106 defrag = 0; 2107 goto restart; 2108 } 2109 2110 /* 2111 * If we are overcomitted then recover the buffer and its 2112 * KVM space. This occurs in rare situations when multiple 2113 * processes are blocked in getnewbuf() or allocbuf(). 2114 */ 2115 if (bufspace >= hibufspace) 2116 flushingbufs = 1; 2117 if (flushingbufs && bp->b_kvasize != 0) { 2118 bp->b_flags |= B_INVAL; 2119 bfreekva(bp); 2120 brelse(bp); 2121 goto restart; 2122 } 2123 if (bufspace < lobufspace) 2124 flushingbufs = 0; 2125 break; 2126 /* NOT REACHED, bufspin not held */ 2127 } 2128 2129 /* 2130 * If we exhausted our list, sleep as appropriate. We may have to 2131 * wakeup various daemons and write out some dirty buffers. 2132 * 2133 * Generally we are sleeping due to insufficient buffer space. 2134 * 2135 * NOTE: bufspin is held if bp is NULL, else it is not held. 2136 */ 2137 if (bp == NULL) { 2138 int flags; 2139 char *waitmsg; 2140 2141 spin_unlock_wr(&bufspin); 2142 if (defrag) { 2143 flags = VFS_BIO_NEED_BUFSPACE; 2144 waitmsg = "nbufkv"; 2145 } else if (bufspace >= hibufspace) { 2146 waitmsg = "nbufbs"; 2147 flags = VFS_BIO_NEED_BUFSPACE; 2148 } else { 2149 waitmsg = "newbuf"; 2150 flags = VFS_BIO_NEED_ANY; 2151 } 2152 2153 needsbuffer |= flags; 2154 bd_speedup(); /* heeeelp */ 2155 while (needsbuffer & flags) { 2156 if (tsleep(&needsbuffer, slpflags, waitmsg, slptimeo)) 2157 return (NULL); 2158 } 2159 } else { 2160 /* 2161 * We finally have a valid bp. We aren't quite out of the 2162 * woods, we still have to reserve kva space. In order 2163 * to keep fragmentation sane we only allocate kva in 2164 * BKVASIZE chunks. 2165 * 2166 * (bufspin is not held) 2167 */ 2168 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2169 2170 if (maxsize != bp->b_kvasize) { 2171 vm_offset_t addr = 0; 2172 int count; 2173 2174 bfreekva(bp); 2175 2176 get_mplock(); 2177 count = vm_map_entry_reserve(MAP_RESERVE_COUNT); 2178 vm_map_lock(&buffer_map); 2179 2180 if (vm_map_findspace(&buffer_map, 2181 vm_map_min(&buffer_map), maxsize, 2182 maxsize, 0, &addr)) { 2183 /* 2184 * Uh oh. Buffer map is too fragmented. We 2185 * must defragment the map. 2186 */ 2187 vm_map_unlock(&buffer_map); 2188 vm_map_entry_release(count); 2189 ++bufdefragcnt; 2190 defrag = 1; 2191 bp->b_flags |= B_INVAL; 2192 rel_mplock(); 2193 brelse(bp); 2194 goto restart; 2195 } 2196 if (addr) { 2197 vm_map_insert(&buffer_map, &count, 2198 NULL, 0, 2199 addr, addr + maxsize, 2200 VM_MAPTYPE_NORMAL, 2201 VM_PROT_ALL, VM_PROT_ALL, 2202 MAP_NOFAULT); 2203 2204 bp->b_kvabase = (caddr_t) addr; 2205 bp->b_kvasize = maxsize; 2206 bufspace += bp->b_kvasize; 2207 ++bufreusecnt; 2208 } 2209 vm_map_unlock(&buffer_map); 2210 vm_map_entry_release(count); 2211 rel_mplock(); 2212 } 2213 bp->b_data = bp->b_kvabase; 2214 } 2215 return(bp); 2216 } 2217 2218 /* 2219 * This routine is called in an emergency to recover VM pages from the 2220 * buffer cache by cashing in clean buffers. The idea is to recover 2221 * enough pages to be able to satisfy a stuck bio_page_alloc(). 2222 */ 2223 static int 2224 recoverbufpages(void) 2225 { 2226 struct buf *bp; 2227 int bytes = 0; 2228 2229 ++recoverbufcalls; 2230 2231 spin_lock_wr(&bufspin); 2232 while (bytes < MAXBSIZE) { 2233 bp = TAILQ_FIRST(&bufqueues[BQUEUE_CLEAN]); 2234 if (bp == NULL) 2235 break; 2236 2237 /* 2238 * BQUEUE_CLEAN - B_AGE special case. If not set the bp 2239 * cycles through the queue twice before being selected. 2240 */ 2241 if ((bp->b_flags & B_AGE) == 0 && TAILQ_NEXT(bp, b_freelist)) { 2242 bp->b_flags |= B_AGE; 2243 TAILQ_REMOVE(&bufqueues[BQUEUE_CLEAN], bp, b_freelist); 2244 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_CLEAN], 2245 bp, b_freelist); 2246 continue; 2247 } 2248 2249 /* 2250 * Sanity Checks 2251 */ 2252 KKASSERT(bp->b_qindex == BQUEUE_CLEAN); 2253 KKASSERT((bp->b_flags & B_DELWRI) == 0); 2254 2255 /* 2256 * Start freeing the bp. This is somewhat involved. 2257 * 2258 * Buffers on the clean list must be disassociated from 2259 * their current vnode 2260 */ 2261 2262 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) { 2263 kprintf("recoverbufpages: warning, locked buf %p, race corrected\n", bp); 2264 tsleep(&bd_request, 0, "gnbxxx", hz / 100); 2265 continue; 2266 } 2267 if (bp->b_qindex != BQUEUE_CLEAN) { 2268 kprintf("recoverbufpages: warning, BUF_LOCK blocked unexpectedly on buf %p index %d, race corrected\n", bp, bp->b_qindex); 2269 BUF_UNLOCK(bp); 2270 continue; 2271 } 2272 bremfree_locked(bp); 2273 spin_unlock_wr(&bufspin); 2274 2275 /* 2276 * Dependancies must be handled before we disassociate the 2277 * vnode. 2278 * 2279 * NOTE: HAMMER will set B_LOCKED if the buffer cannot 2280 * be immediately disassociated. HAMMER then becomes 2281 * responsible for releasing the buffer. 2282 */ 2283 if (LIST_FIRST(&bp->b_dep) != NULL) { 2284 buf_deallocate(bp); 2285 if (bp->b_flags & B_LOCKED) { 2286 bqrelse(bp); 2287 spin_lock_wr(&bufspin); 2288 continue; 2289 } 2290 KKASSERT(LIST_FIRST(&bp->b_dep) == NULL); 2291 } 2292 2293 bytes += bp->b_bufsize; 2294 2295 get_mplock(); 2296 if (bp->b_flags & B_VMIO) { 2297 bp->b_flags |= B_DIRECT; /* try to free pages */ 2298 vfs_vmio_release(bp); 2299 } 2300 if (bp->b_vp) 2301 brelvp(bp); 2302 2303 KKASSERT(bp->b_vp == NULL); 2304 KKASSERT((bp->b_flags & B_HASHED) == 0); 2305 2306 /* 2307 * critical section protection is not required when 2308 * scrapping a buffer's contents because it is already 2309 * wired. 2310 */ 2311 if (bp->b_bufsize) 2312 allocbuf(bp, 0); 2313 rel_mplock(); 2314 2315 bp->b_flags = B_BNOCLIP; 2316 bp->b_cmd = BUF_CMD_DONE; 2317 bp->b_vp = NULL; 2318 bp->b_error = 0; 2319 bp->b_resid = 0; 2320 bp->b_bcount = 0; 2321 bp->b_xio.xio_npages = 0; 2322 bp->b_dirtyoff = bp->b_dirtyend = 0; 2323 reinitbufbio(bp); 2324 KKASSERT(LIST_FIRST(&bp->b_dep) == NULL); 2325 buf_dep_init(bp); 2326 bp->b_flags |= B_INVAL; 2327 /* bfreekva(bp); */ 2328 brelse(bp); 2329 spin_lock_wr(&bufspin); 2330 } 2331 spin_unlock_wr(&bufspin); 2332 return(bytes); 2333 } 2334 2335 /* 2336 * buf_daemon: 2337 * 2338 * Buffer flushing daemon. Buffers are normally flushed by the 2339 * update daemon but if it cannot keep up this process starts to 2340 * take the load in an attempt to prevent getnewbuf() from blocking. 2341 * 2342 * Once a flush is initiated it does not stop until the number 2343 * of buffers falls below lodirtybuffers, but we will wake up anyone 2344 * waiting at the mid-point. 2345 */ 2346 2347 static struct kproc_desc buf_kp = { 2348 "bufdaemon", 2349 buf_daemon, 2350 &bufdaemon_td 2351 }; 2352 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, 2353 kproc_start, &buf_kp) 2354 2355 static struct kproc_desc bufhw_kp = { 2356 "bufdaemon_hw", 2357 buf_daemon_hw, 2358 &bufdaemonhw_td 2359 }; 2360 SYSINIT(bufdaemon_hw, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, 2361 kproc_start, &bufhw_kp) 2362 2363 static void 2364 buf_daemon(void) 2365 { 2366 int limit; 2367 2368 /* 2369 * This process needs to be suspended prior to shutdown sync. 2370 */ 2371 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc, 2372 bufdaemon_td, SHUTDOWN_PRI_LAST); 2373 curthread->td_flags |= TDF_SYSTHREAD; 2374 2375 /* 2376 * This process is allowed to take the buffer cache to the limit 2377 */ 2378 crit_enter(); 2379 2380 for (;;) { 2381 kproc_suspend_loop(); 2382 2383 /* 2384 * Do the flush as long as the number of dirty buffers 2385 * (including those running) exceeds lodirtybufspace. 2386 * 2387 * When flushing limit running I/O to hirunningspace 2388 * Do the flush. Limit the amount of in-transit I/O we 2389 * allow to build up, otherwise we would completely saturate 2390 * the I/O system. Wakeup any waiting processes before we 2391 * normally would so they can run in parallel with our drain. 2392 * 2393 * Our aggregate normal+HW lo water mark is lodirtybufspace, 2394 * but because we split the operation into two threads we 2395 * have to cut it in half for each thread. 2396 */ 2397 waitrunningbufspace(); 2398 limit = lodirtybufspace / 2; 2399 while (runningbufspace + dirtybufspace > limit || 2400 dirtybufcount - dirtybufcounthw >= nbuf / 2) { 2401 if (flushbufqueues(BQUEUE_DIRTY) == 0) 2402 break; 2403 if (runningbufspace < hirunningspace) 2404 continue; 2405 waitrunningbufspace(); 2406 } 2407 2408 /* 2409 * We reached our low water mark, reset the 2410 * request and sleep until we are needed again. 2411 * The sleep is just so the suspend code works. 2412 */ 2413 spin_lock_wr(&needsbuffer_spin); 2414 if (bd_request == 0) { 2415 ssleep(&bd_request, &needsbuffer_spin, 0, 2416 "psleep", hz); 2417 } 2418 bd_request = 0; 2419 spin_unlock_wr(&needsbuffer_spin); 2420 } 2421 } 2422 2423 static void 2424 buf_daemon_hw(void) 2425 { 2426 int limit; 2427 2428 /* 2429 * This process needs to be suspended prior to shutdown sync. 2430 */ 2431 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc, 2432 bufdaemonhw_td, SHUTDOWN_PRI_LAST); 2433 curthread->td_flags |= TDF_SYSTHREAD; 2434 2435 /* 2436 * This process is allowed to take the buffer cache to the limit 2437 */ 2438 crit_enter(); 2439 2440 for (;;) { 2441 kproc_suspend_loop(); 2442 2443 /* 2444 * Do the flush. Limit the amount of in-transit I/O we 2445 * allow to build up, otherwise we would completely saturate 2446 * the I/O system. Wakeup any waiting processes before we 2447 * normally would so they can run in parallel with our drain. 2448 * 2449 * Once we decide to flush push the queued I/O up to 2450 * hirunningspace in order to trigger bursting by the bioq 2451 * subsystem. 2452 * 2453 * Our aggregate normal+HW lo water mark is lodirtybufspace, 2454 * but because we split the operation into two threads we 2455 * have to cut it in half for each thread. 2456 */ 2457 waitrunningbufspace(); 2458 limit = lodirtybufspace / 2; 2459 while (runningbufspace + dirtybufspacehw > limit || 2460 dirtybufcounthw >= nbuf / 2) { 2461 if (flushbufqueues(BQUEUE_DIRTY_HW) == 0) 2462 break; 2463 if (runningbufspace < hirunningspace) 2464 continue; 2465 waitrunningbufspace(); 2466 } 2467 2468 /* 2469 * We reached our low water mark, reset the 2470 * request and sleep until we are needed again. 2471 * The sleep is just so the suspend code works. 2472 */ 2473 spin_lock_wr(&needsbuffer_spin); 2474 if (bd_request_hw == 0) { 2475 ssleep(&bd_request_hw, &needsbuffer_spin, 0, 2476 "psleep", hz); 2477 } 2478 bd_request_hw = 0; 2479 spin_unlock_wr(&needsbuffer_spin); 2480 } 2481 } 2482 2483 /* 2484 * flushbufqueues: 2485 * 2486 * Try to flush a buffer in the dirty queue. We must be careful to 2487 * free up B_INVAL buffers instead of write them, which NFS is 2488 * particularly sensitive to. 2489 * 2490 * B_RELBUF may only be set by VFSs. We do set B_AGE to indicate 2491 * that we really want to try to get the buffer out and reuse it 2492 * due to the write load on the machine. 2493 */ 2494 static int 2495 flushbufqueues(bufq_type_t q) 2496 { 2497 struct buf *bp; 2498 int r = 0; 2499 int spun; 2500 2501 spin_lock_wr(&bufspin); 2502 spun = 1; 2503 2504 bp = TAILQ_FIRST(&bufqueues[q]); 2505 while (bp) { 2506 KASSERT((bp->b_flags & B_DELWRI), 2507 ("unexpected clean buffer %p", bp)); 2508 2509 if (bp->b_flags & B_DELWRI) { 2510 if (bp->b_flags & B_INVAL) { 2511 spin_unlock_wr(&bufspin); 2512 spun = 0; 2513 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) 2514 panic("flushbufqueues: locked buf"); 2515 bremfree(bp); 2516 brelse(bp); 2517 ++r; 2518 break; 2519 } 2520 if (LIST_FIRST(&bp->b_dep) != NULL && 2521 (bp->b_flags & B_DEFERRED) == 0 && 2522 buf_countdeps(bp, 0)) { 2523 TAILQ_REMOVE(&bufqueues[q], bp, b_freelist); 2524 TAILQ_INSERT_TAIL(&bufqueues[q], bp, 2525 b_freelist); 2526 bp->b_flags |= B_DEFERRED; 2527 bp = TAILQ_FIRST(&bufqueues[q]); 2528 continue; 2529 } 2530 2531 /* 2532 * Only write it out if we can successfully lock 2533 * it. If the buffer has a dependancy, 2534 * buf_checkwrite must also return 0 for us to 2535 * be able to initate the write. 2536 * 2537 * If the buffer is flagged B_ERROR it may be 2538 * requeued over and over again, we try to 2539 * avoid a live lock. 2540 */ 2541 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) == 0) { 2542 spin_unlock_wr(&bufspin); 2543 spun = 0; 2544 if (LIST_FIRST(&bp->b_dep) != NULL && 2545 buf_checkwrite(bp)) { 2546 bremfree(bp); 2547 brelse(bp); 2548 } else if (bp->b_flags & B_ERROR) { 2549 tsleep(bp, 0, "bioer", 1); 2550 bp->b_flags &= ~B_AGE; 2551 vfs_bio_awrite(bp); 2552 } else { 2553 bp->b_flags |= B_AGE; 2554 vfs_bio_awrite(bp); 2555 } 2556 ++r; 2557 break; 2558 } 2559 } 2560 bp = TAILQ_NEXT(bp, b_freelist); 2561 } 2562 if (spun) 2563 spin_unlock_wr(&bufspin); 2564 return (r); 2565 } 2566 2567 /* 2568 * inmem: 2569 * 2570 * Returns true if no I/O is needed to access the associated VM object. 2571 * This is like findblk except it also hunts around in the VM system for 2572 * the data. 2573 * 2574 * Note that we ignore vm_page_free() races from interrupts against our 2575 * lookup, since if the caller is not protected our return value will not 2576 * be any more valid then otherwise once we exit the critical section. 2577 */ 2578 int 2579 inmem(struct vnode *vp, off_t loffset) 2580 { 2581 vm_object_t obj; 2582 vm_offset_t toff, tinc, size; 2583 vm_page_t m; 2584 2585 if (findblk(vp, loffset, FINDBLK_TEST)) 2586 return 1; 2587 if (vp->v_mount == NULL) 2588 return 0; 2589 if ((obj = vp->v_object) == NULL) 2590 return 0; 2591 2592 size = PAGE_SIZE; 2593 if (size > vp->v_mount->mnt_stat.f_iosize) 2594 size = vp->v_mount->mnt_stat.f_iosize; 2595 2596 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2597 m = vm_page_lookup(obj, OFF_TO_IDX(loffset + toff)); 2598 if (m == NULL) 2599 return 0; 2600 tinc = size; 2601 if (tinc > PAGE_SIZE - ((toff + loffset) & PAGE_MASK)) 2602 tinc = PAGE_SIZE - ((toff + loffset) & PAGE_MASK); 2603 if (vm_page_is_valid(m, 2604 (vm_offset_t) ((toff + loffset) & PAGE_MASK), tinc) == 0) 2605 return 0; 2606 } 2607 return 1; 2608 } 2609 2610 /* 2611 * findblk: 2612 * 2613 * Locate and return the specified buffer. Unless flagged otherwise, 2614 * a locked buffer will be returned if it exists or NULL if it does not. 2615 * 2616 * findblk()'d buffers are still on the bufqueues and if you intend 2617 * to use your (locked NON-TEST) buffer you need to bremfree(bp) 2618 * and possibly do other stuff to it. 2619 * 2620 * FINDBLK_TEST - Do not lock the buffer. The caller is responsible 2621 * for locking the buffer and ensuring that it remains 2622 * the desired buffer after locking. 2623 * 2624 * FINDBLK_NBLOCK - Lock the buffer non-blocking. If we are unable 2625 * to acquire the lock we return NULL, even if the 2626 * buffer exists. 2627 * 2628 * (0) - Lock the buffer blocking. 2629 * 2630 * MPSAFE 2631 */ 2632 struct buf * 2633 findblk(struct vnode *vp, off_t loffset, int flags) 2634 { 2635 struct buf *bp; 2636 int lkflags; 2637 2638 lkflags = LK_EXCLUSIVE; 2639 if (flags & FINDBLK_NBLOCK) 2640 lkflags |= LK_NOWAIT; 2641 2642 for (;;) { 2643 lwkt_gettoken(&vp->v_token); 2644 bp = buf_rb_hash_RB_LOOKUP(&vp->v_rbhash_tree, loffset); 2645 lwkt_reltoken(&vp->v_token); 2646 if (bp == NULL || (flags & FINDBLK_TEST)) 2647 break; 2648 if (BUF_LOCK(bp, lkflags)) { 2649 bp = NULL; 2650 break; 2651 } 2652 if (bp->b_vp == vp && bp->b_loffset == loffset) 2653 break; 2654 BUF_UNLOCK(bp); 2655 } 2656 return(bp); 2657 } 2658 2659 /* 2660 * getcacheblk: 2661 * 2662 * Similar to getblk() except only returns the buffer if it is 2663 * B_CACHE and requires no other manipulation. Otherwise NULL 2664 * is returned. 2665 * 2666 * If B_RAM is set the buffer might be just fine, but we return 2667 * NULL anyway because we want the code to fall through to the 2668 * cluster read. Otherwise read-ahead breaks. 2669 */ 2670 struct buf * 2671 getcacheblk(struct vnode *vp, off_t loffset) 2672 { 2673 struct buf *bp; 2674 2675 bp = findblk(vp, loffset, 0); 2676 if (bp) { 2677 if ((bp->b_flags & (B_INVAL | B_CACHE | B_RAM)) == B_CACHE) { 2678 bp->b_flags &= ~B_AGE; 2679 bremfree(bp); 2680 } else { 2681 BUF_UNLOCK(bp); 2682 bp = NULL; 2683 } 2684 } 2685 return (bp); 2686 } 2687 2688 /* 2689 * getblk: 2690 * 2691 * Get a block given a specified block and offset into a file/device. 2692 * B_INVAL may or may not be set on return. The caller should clear 2693 * B_INVAL prior to initiating a READ. 2694 * 2695 * IT IS IMPORTANT TO UNDERSTAND THAT IF YOU CALL GETBLK() AND B_CACHE 2696 * IS NOT SET, YOU MUST INITIALIZE THE RETURNED BUFFER, ISSUE A READ, 2697 * OR SET B_INVAL BEFORE RETIRING IT. If you retire a getblk'd buffer 2698 * without doing any of those things the system will likely believe 2699 * the buffer to be valid (especially if it is not B_VMIO), and the 2700 * next getblk() will return the buffer with B_CACHE set. 2701 * 2702 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2703 * an existing buffer. 2704 * 2705 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2706 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2707 * and then cleared based on the backing VM. If the previous buffer is 2708 * non-0-sized but invalid, B_CACHE will be cleared. 2709 * 2710 * If getblk() must create a new buffer, the new buffer is returned with 2711 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2712 * case it is returned with B_INVAL clear and B_CACHE set based on the 2713 * backing VM. 2714 * 2715 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 2716 * B_CACHE bit is clear. 2717 * 2718 * What this means, basically, is that the caller should use B_CACHE to 2719 * determine whether the buffer is fully valid or not and should clear 2720 * B_INVAL prior to issuing a read. If the caller intends to validate 2721 * the buffer by loading its data area with something, the caller needs 2722 * to clear B_INVAL. If the caller does this without issuing an I/O, 2723 * the caller should set B_CACHE ( as an optimization ), else the caller 2724 * should issue the I/O and biodone() will set B_CACHE if the I/O was 2725 * a write attempt or if it was a successfull read. If the caller 2726 * intends to issue a READ, the caller must clear B_INVAL and B_ERROR 2727 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 2728 * 2729 * getblk flags: 2730 * 2731 * GETBLK_PCATCH - catch signal if blocked, can cause NULL return 2732 * GETBLK_BHEAVY - heavy-weight buffer cache buffer 2733 * 2734 * MPALMOSTSAFE 2735 */ 2736 struct buf * 2737 getblk(struct vnode *vp, off_t loffset, int size, int blkflags, int slptimeo) 2738 { 2739 struct buf *bp; 2740 int slpflags = (blkflags & GETBLK_PCATCH) ? PCATCH : 0; 2741 int error; 2742 int lkflags; 2743 2744 if (size > MAXBSIZE) 2745 panic("getblk: size(%d) > MAXBSIZE(%d)", size, MAXBSIZE); 2746 if (vp->v_object == NULL) 2747 panic("getblk: vnode %p has no object!", vp); 2748 2749 loop: 2750 if ((bp = findblk(vp, loffset, FINDBLK_TEST)) != NULL) { 2751 /* 2752 * The buffer was found in the cache, but we need to lock it. 2753 * Even with LK_NOWAIT the lockmgr may break our critical 2754 * section, so double-check the validity of the buffer 2755 * once the lock has been obtained. 2756 */ 2757 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) { 2758 if (blkflags & GETBLK_NOWAIT) 2759 return(NULL); 2760 lkflags = LK_EXCLUSIVE | LK_SLEEPFAIL; 2761 if (blkflags & GETBLK_PCATCH) 2762 lkflags |= LK_PCATCH; 2763 error = BUF_TIMELOCK(bp, lkflags, "getblk", slptimeo); 2764 if (error) { 2765 if (error == ENOLCK) 2766 goto loop; 2767 return (NULL); 2768 } 2769 /* buffer may have changed on us */ 2770 } 2771 2772 /* 2773 * Once the buffer has been locked, make sure we didn't race 2774 * a buffer recyclement. Buffers that are no longer hashed 2775 * will have b_vp == NULL, so this takes care of that check 2776 * as well. 2777 */ 2778 if (bp->b_vp != vp || bp->b_loffset != loffset) { 2779 kprintf("Warning buffer %p (vp %p loffset %lld) " 2780 "was recycled\n", 2781 bp, vp, (long long)loffset); 2782 BUF_UNLOCK(bp); 2783 goto loop; 2784 } 2785 2786 /* 2787 * If SZMATCH any pre-existing buffer must be of the requested 2788 * size or NULL is returned. The caller absolutely does not 2789 * want getblk() to bwrite() the buffer on a size mismatch. 2790 */ 2791 if ((blkflags & GETBLK_SZMATCH) && size != bp->b_bcount) { 2792 BUF_UNLOCK(bp); 2793 return(NULL); 2794 } 2795 2796 /* 2797 * All vnode-based buffers must be backed by a VM object. 2798 */ 2799 KKASSERT(bp->b_flags & B_VMIO); 2800 KKASSERT(bp->b_cmd == BUF_CMD_DONE); 2801 bp->b_flags &= ~B_AGE; 2802 2803 /* 2804 * Make sure that B_INVAL buffers do not have a cached 2805 * block number translation. 2806 */ 2807 if ((bp->b_flags & B_INVAL) && (bp->b_bio2.bio_offset != NOOFFSET)) { 2808 kprintf("Warning invalid buffer %p (vp %p loffset %lld)" 2809 " did not have cleared bio_offset cache\n", 2810 bp, vp, (long long)loffset); 2811 clearbiocache(&bp->b_bio2); 2812 } 2813 2814 /* 2815 * The buffer is locked. B_CACHE is cleared if the buffer is 2816 * invalid. 2817 */ 2818 if (bp->b_flags & B_INVAL) 2819 bp->b_flags &= ~B_CACHE; 2820 bremfree(bp); 2821 2822 /* 2823 * Any size inconsistancy with a dirty buffer or a buffer 2824 * with a softupdates dependancy must be resolved. Resizing 2825 * the buffer in such circumstances can lead to problems. 2826 * 2827 * Dirty or dependant buffers are written synchronously. 2828 * Other types of buffers are simply released and 2829 * reconstituted as they may be backed by valid, dirty VM 2830 * pages (but not marked B_DELWRI). 2831 * 2832 * NFS NOTE: NFS buffers which straddle EOF are oddly-sized 2833 * and may be left over from a prior truncation (and thus 2834 * no longer represent the actual EOF point), so we 2835 * definitely do not want to B_NOCACHE the backing store. 2836 */ 2837 if (size != bp->b_bcount) { 2838 get_mplock(); 2839 if (bp->b_flags & B_DELWRI) { 2840 bp->b_flags |= B_RELBUF; 2841 bwrite(bp); 2842 } else if (LIST_FIRST(&bp->b_dep)) { 2843 bp->b_flags |= B_RELBUF; 2844 bwrite(bp); 2845 } else { 2846 bp->b_flags |= B_RELBUF; 2847 brelse(bp); 2848 } 2849 rel_mplock(); 2850 goto loop; 2851 } 2852 KKASSERT(size <= bp->b_kvasize); 2853 KASSERT(bp->b_loffset != NOOFFSET, 2854 ("getblk: no buffer offset")); 2855 2856 /* 2857 * A buffer with B_DELWRI set and B_CACHE clear must 2858 * be committed before we can return the buffer in 2859 * order to prevent the caller from issuing a read 2860 * ( due to B_CACHE not being set ) and overwriting 2861 * it. 2862 * 2863 * Most callers, including NFS and FFS, need this to 2864 * operate properly either because they assume they 2865 * can issue a read if B_CACHE is not set, or because 2866 * ( for example ) an uncached B_DELWRI might loop due 2867 * to softupdates re-dirtying the buffer. In the latter 2868 * case, B_CACHE is set after the first write completes, 2869 * preventing further loops. 2870 * 2871 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 2872 * above while extending the buffer, we cannot allow the 2873 * buffer to remain with B_CACHE set after the write 2874 * completes or it will represent a corrupt state. To 2875 * deal with this we set B_NOCACHE to scrap the buffer 2876 * after the write. 2877 * 2878 * XXX Should this be B_RELBUF instead of B_NOCACHE? 2879 * I'm not even sure this state is still possible 2880 * now that getblk() writes out any dirty buffers 2881 * on size changes. 2882 * 2883 * We might be able to do something fancy, like setting 2884 * B_CACHE in bwrite() except if B_DELWRI is already set, 2885 * so the below call doesn't set B_CACHE, but that gets real 2886 * confusing. This is much easier. 2887 */ 2888 2889 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 2890 get_mplock(); 2891 kprintf("getblk: Warning, bp %p loff=%jx DELWRI set " 2892 "and CACHE clear, b_flags %08x\n", 2893 bp, (intmax_t)bp->b_loffset, bp->b_flags); 2894 bp->b_flags |= B_NOCACHE; 2895 bwrite(bp); 2896 rel_mplock(); 2897 goto loop; 2898 } 2899 } else { 2900 /* 2901 * Buffer is not in-core, create new buffer. The buffer 2902 * returned by getnewbuf() is locked. Note that the returned 2903 * buffer is also considered valid (not marked B_INVAL). 2904 * 2905 * Calculating the offset for the I/O requires figuring out 2906 * the block size. We use DEV_BSIZE for VBLK or VCHR and 2907 * the mount's f_iosize otherwise. If the vnode does not 2908 * have an associated mount we assume that the passed size is 2909 * the block size. 2910 * 2911 * Note that vn_isdisk() cannot be used here since it may 2912 * return a failure for numerous reasons. Note that the 2913 * buffer size may be larger then the block size (the caller 2914 * will use block numbers with the proper multiple). Beware 2915 * of using any v_* fields which are part of unions. In 2916 * particular, in DragonFly the mount point overloading 2917 * mechanism uses the namecache only and the underlying 2918 * directory vnode is not a special case. 2919 */ 2920 int bsize, maxsize; 2921 2922 if (vp->v_type == VBLK || vp->v_type == VCHR) 2923 bsize = DEV_BSIZE; 2924 else if (vp->v_mount) 2925 bsize = vp->v_mount->mnt_stat.f_iosize; 2926 else 2927 bsize = size; 2928 2929 maxsize = size + (loffset & PAGE_MASK); 2930 maxsize = imax(maxsize, bsize); 2931 2932 bp = getnewbuf(blkflags, slptimeo, size, maxsize); 2933 if (bp == NULL) { 2934 if (slpflags || slptimeo) 2935 return NULL; 2936 goto loop; 2937 } 2938 2939 /* 2940 * Atomically insert the buffer into the hash, so that it can 2941 * be found by findblk(). 2942 * 2943 * If bgetvp() returns non-zero a collision occured, and the 2944 * bp will not be associated with the vnode. 2945 * 2946 * Make sure the translation layer has been cleared. 2947 */ 2948 bp->b_loffset = loffset; 2949 bp->b_bio2.bio_offset = NOOFFSET; 2950 /* bp->b_bio2.bio_next = NULL; */ 2951 2952 if (bgetvp(vp, bp)) { 2953 bp->b_flags |= B_INVAL; 2954 brelse(bp); 2955 goto loop; 2956 } 2957 2958 /* 2959 * All vnode-based buffers must be backed by a VM object. 2960 */ 2961 KKASSERT(vp->v_object != NULL); 2962 bp->b_flags |= B_VMIO; 2963 KKASSERT(bp->b_cmd == BUF_CMD_DONE); 2964 2965 get_mplock(); 2966 allocbuf(bp, size); 2967 rel_mplock(); 2968 } 2969 KKASSERT(dsched_is_clear_buf_priv(bp)); 2970 return (bp); 2971 } 2972 2973 /* 2974 * regetblk(bp) 2975 * 2976 * Reacquire a buffer that was previously released to the locked queue, 2977 * or reacquire a buffer which is interlocked by having bioops->io_deallocate 2978 * set B_LOCKED (which handles the acquisition race). 2979 * 2980 * To this end, either B_LOCKED must be set or the dependancy list must be 2981 * non-empty. 2982 * 2983 * MPSAFE 2984 */ 2985 void 2986 regetblk(struct buf *bp) 2987 { 2988 KKASSERT((bp->b_flags & B_LOCKED) || LIST_FIRST(&bp->b_dep) != NULL); 2989 BUF_LOCK(bp, LK_EXCLUSIVE | LK_RETRY); 2990 bremfree(bp); 2991 } 2992 2993 /* 2994 * geteblk: 2995 * 2996 * Get an empty, disassociated buffer of given size. The buffer is 2997 * initially set to B_INVAL. 2998 * 2999 * critical section protection is not required for the allocbuf() 3000 * call because races are impossible here. 3001 * 3002 * MPALMOSTSAFE 3003 */ 3004 struct buf * 3005 geteblk(int size) 3006 { 3007 struct buf *bp; 3008 int maxsize; 3009 3010 maxsize = (size + BKVAMASK) & ~BKVAMASK; 3011 3012 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0) 3013 ; 3014 get_mplock(); 3015 allocbuf(bp, size); 3016 rel_mplock(); 3017 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 3018 KKASSERT(dsched_is_clear_buf_priv(bp)); 3019 return (bp); 3020 } 3021 3022 3023 /* 3024 * allocbuf: 3025 * 3026 * This code constitutes the buffer memory from either anonymous system 3027 * memory (in the case of non-VMIO operations) or from an associated 3028 * VM object (in the case of VMIO operations). This code is able to 3029 * resize a buffer up or down. 3030 * 3031 * Note that this code is tricky, and has many complications to resolve 3032 * deadlock or inconsistant data situations. Tread lightly!!! 3033 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 3034 * the caller. Calling this code willy nilly can result in the loss of data. 3035 * 3036 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 3037 * B_CACHE for the non-VMIO case. 3038 * 3039 * This routine does not need to be called from a critical section but you 3040 * must own the buffer. 3041 * 3042 * NOTMPSAFE 3043 */ 3044 int 3045 allocbuf(struct buf *bp, int size) 3046 { 3047 int newbsize, mbsize; 3048 int i; 3049 3050 if (BUF_REFCNT(bp) == 0) 3051 panic("allocbuf: buffer not busy"); 3052 3053 if (bp->b_kvasize < size) 3054 panic("allocbuf: buffer too small"); 3055 3056 if ((bp->b_flags & B_VMIO) == 0) { 3057 caddr_t origbuf; 3058 int origbufsize; 3059 /* 3060 * Just get anonymous memory from the kernel. Don't 3061 * mess with B_CACHE. 3062 */ 3063 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3064 if (bp->b_flags & B_MALLOC) 3065 newbsize = mbsize; 3066 else 3067 newbsize = round_page(size); 3068 3069 if (newbsize < bp->b_bufsize) { 3070 /* 3071 * Malloced buffers are not shrunk 3072 */ 3073 if (bp->b_flags & B_MALLOC) { 3074 if (newbsize) { 3075 bp->b_bcount = size; 3076 } else { 3077 kfree(bp->b_data, M_BIOBUF); 3078 if (bp->b_bufsize) { 3079 bufmallocspace -= bp->b_bufsize; 3080 bufspacewakeup(); 3081 bp->b_bufsize = 0; 3082 } 3083 bp->b_data = bp->b_kvabase; 3084 bp->b_bcount = 0; 3085 bp->b_flags &= ~B_MALLOC; 3086 } 3087 return 1; 3088 } 3089 vm_hold_free_pages( 3090 bp, 3091 (vm_offset_t) bp->b_data + newbsize, 3092 (vm_offset_t) bp->b_data + bp->b_bufsize); 3093 } else if (newbsize > bp->b_bufsize) { 3094 /* 3095 * We only use malloced memory on the first allocation. 3096 * and revert to page-allocated memory when the buffer 3097 * grows. 3098 */ 3099 if ((bufmallocspace < maxbufmallocspace) && 3100 (bp->b_bufsize == 0) && 3101 (mbsize <= PAGE_SIZE/2)) { 3102 3103 bp->b_data = kmalloc(mbsize, M_BIOBUF, M_WAITOK); 3104 bp->b_bufsize = mbsize; 3105 bp->b_bcount = size; 3106 bp->b_flags |= B_MALLOC; 3107 bufmallocspace += mbsize; 3108 return 1; 3109 } 3110 origbuf = NULL; 3111 origbufsize = 0; 3112 /* 3113 * If the buffer is growing on its other-than-first 3114 * allocation, then we revert to the page-allocation 3115 * scheme. 3116 */ 3117 if (bp->b_flags & B_MALLOC) { 3118 origbuf = bp->b_data; 3119 origbufsize = bp->b_bufsize; 3120 bp->b_data = bp->b_kvabase; 3121 if (bp->b_bufsize) { 3122 bufmallocspace -= bp->b_bufsize; 3123 bufspacewakeup(); 3124 bp->b_bufsize = 0; 3125 } 3126 bp->b_flags &= ~B_MALLOC; 3127 newbsize = round_page(newbsize); 3128 } 3129 vm_hold_load_pages( 3130 bp, 3131 (vm_offset_t) bp->b_data + bp->b_bufsize, 3132 (vm_offset_t) bp->b_data + newbsize); 3133 if (origbuf) { 3134 bcopy(origbuf, bp->b_data, origbufsize); 3135 kfree(origbuf, M_BIOBUF); 3136 } 3137 } 3138 } else { 3139 vm_page_t m; 3140 int desiredpages; 3141 3142 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3143 desiredpages = ((int)(bp->b_loffset & PAGE_MASK) + 3144 newbsize + PAGE_MASK) >> PAGE_SHIFT; 3145 KKASSERT(desiredpages <= XIO_INTERNAL_PAGES); 3146 3147 if (bp->b_flags & B_MALLOC) 3148 panic("allocbuf: VMIO buffer can't be malloced"); 3149 /* 3150 * Set B_CACHE initially if buffer is 0 length or will become 3151 * 0-length. 3152 */ 3153 if (size == 0 || bp->b_bufsize == 0) 3154 bp->b_flags |= B_CACHE; 3155 3156 if (newbsize < bp->b_bufsize) { 3157 /* 3158 * DEV_BSIZE aligned new buffer size is less then the 3159 * DEV_BSIZE aligned existing buffer size. Figure out 3160 * if we have to remove any pages. 3161 */ 3162 if (desiredpages < bp->b_xio.xio_npages) { 3163 for (i = desiredpages; i < bp->b_xio.xio_npages; i++) { 3164 /* 3165 * the page is not freed here -- it 3166 * is the responsibility of 3167 * vnode_pager_setsize 3168 */ 3169 m = bp->b_xio.xio_pages[i]; 3170 KASSERT(m != bogus_page, 3171 ("allocbuf: bogus page found")); 3172 while (vm_page_sleep_busy(m, TRUE, "biodep")) 3173 ; 3174 3175 bp->b_xio.xio_pages[i] = NULL; 3176 vm_page_unwire(m, 0); 3177 } 3178 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) + 3179 (desiredpages << PAGE_SHIFT), (bp->b_xio.xio_npages - desiredpages)); 3180 bp->b_xio.xio_npages = desiredpages; 3181 } 3182 } else if (size > bp->b_bcount) { 3183 /* 3184 * We are growing the buffer, possibly in a 3185 * byte-granular fashion. 3186 */ 3187 struct vnode *vp; 3188 vm_object_t obj; 3189 vm_offset_t toff; 3190 vm_offset_t tinc; 3191 3192 /* 3193 * Step 1, bring in the VM pages from the object, 3194 * allocating them if necessary. We must clear 3195 * B_CACHE if these pages are not valid for the 3196 * range covered by the buffer. 3197 * 3198 * critical section protection is required to protect 3199 * against interrupts unbusying and freeing pages 3200 * between our vm_page_lookup() and our 3201 * busycheck/wiring call. 3202 */ 3203 vp = bp->b_vp; 3204 obj = vp->v_object; 3205 3206 crit_enter(); 3207 while (bp->b_xio.xio_npages < desiredpages) { 3208 vm_page_t m; 3209 vm_pindex_t pi; 3210 3211 pi = OFF_TO_IDX(bp->b_loffset) + bp->b_xio.xio_npages; 3212 if ((m = vm_page_lookup(obj, pi)) == NULL) { 3213 /* 3214 * note: must allocate system pages 3215 * since blocking here could intefere 3216 * with paging I/O, no matter which 3217 * process we are. 3218 */ 3219 m = bio_page_alloc(obj, pi, desiredpages - bp->b_xio.xio_npages); 3220 if (m) { 3221 vm_page_wire(m); 3222 vm_page_wakeup(m); 3223 vm_page_flag_clear(m, PG_ZERO); 3224 bp->b_flags &= ~B_CACHE; 3225 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 3226 ++bp->b_xio.xio_npages; 3227 } 3228 continue; 3229 } 3230 3231 /* 3232 * We found a page. If we have to sleep on it, 3233 * retry because it might have gotten freed out 3234 * from under us. 3235 * 3236 * We can only test PG_BUSY here. Blocking on 3237 * m->busy might lead to a deadlock: 3238 * 3239 * vm_fault->getpages->cluster_read->allocbuf 3240 * 3241 */ 3242 3243 if (vm_page_sleep_busy(m, FALSE, "pgtblk")) 3244 continue; 3245 vm_page_flag_clear(m, PG_ZERO); 3246 vm_page_wire(m); 3247 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 3248 ++bp->b_xio.xio_npages; 3249 if (bp->b_act_count < m->act_count) 3250 bp->b_act_count = m->act_count; 3251 } 3252 crit_exit(); 3253 3254 /* 3255 * Step 2. We've loaded the pages into the buffer, 3256 * we have to figure out if we can still have B_CACHE 3257 * set. Note that B_CACHE is set according to the 3258 * byte-granular range ( bcount and size ), not the 3259 * aligned range ( newbsize ). 3260 * 3261 * The VM test is against m->valid, which is DEV_BSIZE 3262 * aligned. Needless to say, the validity of the data 3263 * needs to also be DEV_BSIZE aligned. Note that this 3264 * fails with NFS if the server or some other client 3265 * extends the file's EOF. If our buffer is resized, 3266 * B_CACHE may remain set! XXX 3267 */ 3268 3269 toff = bp->b_bcount; 3270 tinc = PAGE_SIZE - ((bp->b_loffset + toff) & PAGE_MASK); 3271 3272 while ((bp->b_flags & B_CACHE) && toff < size) { 3273 vm_pindex_t pi; 3274 3275 if (tinc > (size - toff)) 3276 tinc = size - toff; 3277 3278 pi = ((bp->b_loffset & PAGE_MASK) + toff) >> 3279 PAGE_SHIFT; 3280 3281 vfs_buf_test_cache( 3282 bp, 3283 bp->b_loffset, 3284 toff, 3285 tinc, 3286 bp->b_xio.xio_pages[pi] 3287 ); 3288 toff += tinc; 3289 tinc = PAGE_SIZE; 3290 } 3291 3292 /* 3293 * Step 3, fixup the KVM pmap. Remember that 3294 * bp->b_data is relative to bp->b_loffset, but 3295 * bp->b_loffset may be offset into the first page. 3296 */ 3297 3298 bp->b_data = (caddr_t) 3299 trunc_page((vm_offset_t)bp->b_data); 3300 pmap_qenter( 3301 (vm_offset_t)bp->b_data, 3302 bp->b_xio.xio_pages, 3303 bp->b_xio.xio_npages 3304 ); 3305 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 3306 (vm_offset_t)(bp->b_loffset & PAGE_MASK)); 3307 } 3308 } 3309 3310 /* adjust space use on already-dirty buffer */ 3311 if (bp->b_flags & B_DELWRI) { 3312 dirtybufspace += newbsize - bp->b_bufsize; 3313 if (bp->b_flags & B_HEAVY) 3314 dirtybufspacehw += newbsize - bp->b_bufsize; 3315 } 3316 if (newbsize < bp->b_bufsize) 3317 bufspacewakeup(); 3318 bp->b_bufsize = newbsize; /* actual buffer allocation */ 3319 bp->b_bcount = size; /* requested buffer size */ 3320 return 1; 3321 } 3322 3323 /* 3324 * biowait: 3325 * 3326 * Wait for buffer I/O completion, returning error status. B_EINTR 3327 * is converted into an EINTR error but not cleared (since a chain 3328 * of biowait() calls may occur). 3329 * 3330 * On return bpdone() will have been called but the buffer will remain 3331 * locked and will not have been brelse()'d. 3332 * 3333 * NOTE! If a timeout is specified and ETIMEDOUT occurs the I/O is 3334 * likely still in progress on return. 3335 * 3336 * NOTE! This operation is on a BIO, not a BUF. 3337 * 3338 * NOTE! BIO_DONE is cleared by vn_strategy() 3339 * 3340 * MPSAFE 3341 */ 3342 static __inline int 3343 _biowait(struct bio *bio, const char *wmesg, int to) 3344 { 3345 struct buf *bp = bio->bio_buf; 3346 u_int32_t flags; 3347 u_int32_t nflags; 3348 int error; 3349 3350 KKASSERT(bio == &bp->b_bio1); 3351 for (;;) { 3352 flags = bio->bio_flags; 3353 if (flags & BIO_DONE) 3354 break; 3355 tsleep_interlock(bio, 0); 3356 nflags = flags | BIO_WANT; 3357 tsleep_interlock(bio, 0); 3358 if (atomic_cmpset_int(&bio->bio_flags, flags, nflags)) { 3359 if (wmesg) 3360 error = tsleep(bio, PINTERLOCKED, wmesg, to); 3361 else if (bp->b_cmd == BUF_CMD_READ) 3362 error = tsleep(bio, PINTERLOCKED, "biord", to); 3363 else 3364 error = tsleep(bio, PINTERLOCKED, "biowr", to); 3365 if (error) { 3366 kprintf("tsleep error biowait %d\n", error); 3367 return (error); 3368 } 3369 } 3370 } 3371 3372 /* 3373 * Finish up. 3374 */ 3375 KKASSERT(bp->b_cmd == BUF_CMD_DONE); 3376 bio->bio_flags &= ~(BIO_DONE | BIO_SYNC); 3377 if (bp->b_flags & B_EINTR) 3378 return (EINTR); 3379 if (bp->b_flags & B_ERROR) 3380 return (bp->b_error ? bp->b_error : EIO); 3381 return (0); 3382 } 3383 3384 int 3385 biowait(struct bio *bio, const char *wmesg) 3386 { 3387 return(_biowait(bio, wmesg, 0)); 3388 } 3389 3390 int 3391 biowait_timeout(struct bio *bio, const char *wmesg, int to) 3392 { 3393 return(_biowait(bio, wmesg, to)); 3394 } 3395 3396 /* 3397 * This associates a tracking count with an I/O. vn_strategy() and 3398 * dev_dstrategy() do this automatically but there are a few cases 3399 * where a vnode or device layer is bypassed when a block translation 3400 * is cached. In such cases bio_start_transaction() may be called on 3401 * the bypassed layers so the system gets an I/O in progress indication 3402 * for those higher layers. 3403 */ 3404 void 3405 bio_start_transaction(struct bio *bio, struct bio_track *track) 3406 { 3407 bio->bio_track = track; 3408 if (dsched_is_clear_buf_priv(bio->bio_buf)) 3409 dsched_new_buf(bio->bio_buf); 3410 bio_track_ref(track); 3411 } 3412 3413 /* 3414 * Initiate I/O on a vnode. 3415 * 3416 * SWAPCACHE OPERATION: 3417 * 3418 * Real buffer cache buffers have a non-NULL bp->b_vp. Unfortunately 3419 * devfs also uses b_vp for fake buffers so we also have to check 3420 * that B_PAGING is 0. In this case the passed 'vp' is probably the 3421 * underlying block device. The swap assignments are related to the 3422 * buffer cache buffer's b_vp, not the passed vp. 3423 * 3424 * The passed vp == bp->b_vp only in the case where the strategy call 3425 * is made on the vp itself for its own buffers (a regular file or 3426 * block device vp). The filesystem usually then re-calls vn_strategy() 3427 * after translating the request to an underlying device. 3428 * 3429 * Cluster buffers set B_CLUSTER and the passed vp is the vp of the 3430 * underlying buffer cache buffers. 3431 * 3432 * We can only deal with page-aligned buffers at the moment, because 3433 * we can't tell what the real dirty state for pages straddling a buffer 3434 * are. 3435 * 3436 * In order to call swap_pager_strategy() we must provide the VM object 3437 * and base offset for the underlying buffer cache pages so it can find 3438 * the swap blocks. 3439 */ 3440 void 3441 vn_strategy(struct vnode *vp, struct bio *bio) 3442 { 3443 struct bio_track *track; 3444 struct buf *bp = bio->bio_buf; 3445 3446 KKASSERT(bp->b_cmd != BUF_CMD_DONE); 3447 3448 /* 3449 * Handle the swap cache intercept. 3450 */ 3451 if (vn_cache_strategy(vp, bio)) 3452 return; 3453 3454 /* 3455 * Otherwise do the operation through the filesystem 3456 */ 3457 if (bp->b_cmd == BUF_CMD_READ) 3458 track = &vp->v_track_read; 3459 else 3460 track = &vp->v_track_write; 3461 KKASSERT((bio->bio_flags & BIO_DONE) == 0); 3462 bio->bio_track = track; 3463 if (dsched_is_clear_buf_priv(bio->bio_buf)) 3464 dsched_new_buf(bio->bio_buf); 3465 bio_track_ref(track); 3466 vop_strategy(*vp->v_ops, vp, bio); 3467 } 3468 3469 int 3470 vn_cache_strategy(struct vnode *vp, struct bio *bio) 3471 { 3472 struct buf *bp = bio->bio_buf; 3473 struct bio *nbio; 3474 vm_object_t object; 3475 vm_page_t m; 3476 int i; 3477 3478 /* 3479 * Is this buffer cache buffer suitable for reading from 3480 * the swap cache? 3481 */ 3482 if (vm_swapcache_read_enable == 0 || 3483 bp->b_cmd != BUF_CMD_READ || 3484 ((bp->b_flags & B_CLUSTER) == 0 && 3485 (bp->b_vp == NULL || (bp->b_flags & B_PAGING))) || 3486 ((int)bp->b_loffset & PAGE_MASK) != 0 || 3487 (bp->b_bcount & PAGE_MASK) != 0) { 3488 return(0); 3489 } 3490 3491 /* 3492 * Figure out the original VM object (it will match the underlying 3493 * VM pages). Note that swap cached data uses page indices relative 3494 * to that object, not relative to bio->bio_offset. 3495 */ 3496 if (bp->b_flags & B_CLUSTER) 3497 object = vp->v_object; 3498 else 3499 object = bp->b_vp->v_object; 3500 3501 /* 3502 * In order to be able to use the swap cache all underlying VM 3503 * pages must be marked as such, and we can't have any bogus pages. 3504 */ 3505 for (i = 0; i < bp->b_xio.xio_npages; ++i) { 3506 m = bp->b_xio.xio_pages[i]; 3507 if ((m->flags & PG_SWAPPED) == 0) 3508 break; 3509 if (m == bogus_page) 3510 break; 3511 } 3512 3513 /* 3514 * If we are good then issue the I/O using swap_pager_strategy() 3515 */ 3516 if (i == bp->b_xio.xio_npages) { 3517 m = bp->b_xio.xio_pages[0]; 3518 nbio = push_bio(bio); 3519 nbio->bio_offset = ptoa(m->pindex); 3520 KKASSERT(m->object == object); 3521 swap_pager_strategy(object, nbio); 3522 return(1); 3523 } 3524 return(0); 3525 } 3526 3527 /* 3528 * bpdone: 3529 * 3530 * Finish I/O on a buffer after all BIOs have been processed. 3531 * Called when the bio chain is exhausted or by biowait. If called 3532 * by biowait, elseit is typically 0. 3533 * 3534 * bpdone is also responsible for setting B_CACHE in a B_VMIO bp. 3535 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3536 * assuming B_INVAL is clear. 3537 * 3538 * For the VMIO case, we set B_CACHE if the op was a read and no 3539 * read error occured, or if the op was a write. B_CACHE is never 3540 * set if the buffer is invalid or otherwise uncacheable. 3541 * 3542 * bpdone does not mess with B_INVAL, allowing the I/O routine or the 3543 * initiator to leave B_INVAL set to brelse the buffer out of existance 3544 * in the biodone routine. 3545 */ 3546 void 3547 bpdone(struct buf *bp, int elseit) 3548 { 3549 buf_cmd_t cmd; 3550 3551 KASSERT(BUF_REFCNTNB(bp) > 0, 3552 ("biodone: bp %p not busy %d", bp, BUF_REFCNTNB(bp))); 3553 KASSERT(bp->b_cmd != BUF_CMD_DONE, 3554 ("biodone: bp %p already done!", bp)); 3555 3556 /* 3557 * No more BIOs are left. All completion functions have been dealt 3558 * with, now we clean up the buffer. 3559 */ 3560 cmd = bp->b_cmd; 3561 bp->b_cmd = BUF_CMD_DONE; 3562 3563 /* 3564 * Only reads and writes are processed past this point. 3565 */ 3566 if (cmd != BUF_CMD_READ && cmd != BUF_CMD_WRITE) { 3567 if (cmd == BUF_CMD_FREEBLKS) 3568 bp->b_flags |= B_NOCACHE; 3569 if (elseit) 3570 brelse(bp); 3571 return; 3572 } 3573 3574 /* 3575 * Warning: softupdates may re-dirty the buffer, and HAMMER can do 3576 * a lot worse. XXX - move this above the clearing of b_cmd 3577 */ 3578 if (LIST_FIRST(&bp->b_dep) != NULL) 3579 buf_complete(bp); 3580 3581 /* 3582 * A failed write must re-dirty the buffer unless B_INVAL 3583 * was set. Only applicable to normal buffers (with VPs). 3584 * vinum buffers may not have a vp. 3585 */ 3586 if (cmd == BUF_CMD_WRITE && 3587 (bp->b_flags & (B_ERROR | B_INVAL)) == B_ERROR) { 3588 bp->b_flags &= ~B_NOCACHE; 3589 if (bp->b_vp) 3590 bdirty(bp); 3591 } 3592 3593 if (bp->b_flags & B_VMIO) { 3594 int i; 3595 vm_ooffset_t foff; 3596 vm_page_t m; 3597 vm_object_t obj; 3598 int iosize; 3599 struct vnode *vp = bp->b_vp; 3600 3601 obj = vp->v_object; 3602 3603 #if defined(VFS_BIO_DEBUG) 3604 if (vp->v_auxrefs == 0) 3605 panic("biodone: zero vnode hold count"); 3606 if ((vp->v_flag & VOBJBUF) == 0) 3607 panic("biodone: vnode is not setup for merged cache"); 3608 #endif 3609 3610 foff = bp->b_loffset; 3611 KASSERT(foff != NOOFFSET, ("biodone: no buffer offset")); 3612 KASSERT(obj != NULL, ("biodone: missing VM object")); 3613 3614 #if defined(VFS_BIO_DEBUG) 3615 if (obj->paging_in_progress < bp->b_xio.xio_npages) { 3616 kprintf("biodone: paging in progress(%d) < bp->b_xio.xio_npages(%d)\n", 3617 obj->paging_in_progress, bp->b_xio.xio_npages); 3618 } 3619 #endif 3620 3621 /* 3622 * Set B_CACHE if the op was a normal read and no error 3623 * occured. B_CACHE is set for writes in the b*write() 3624 * routines. 3625 */ 3626 iosize = bp->b_bcount - bp->b_resid; 3627 if (cmd == BUF_CMD_READ && 3628 (bp->b_flags & (B_INVAL|B_NOCACHE|B_ERROR)) == 0) { 3629 bp->b_flags |= B_CACHE; 3630 } 3631 3632 crit_enter(); 3633 get_mplock(); 3634 for (i = 0; i < bp->b_xio.xio_npages; i++) { 3635 int bogusflag = 0; 3636 int resid; 3637 3638 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 3639 if (resid > iosize) 3640 resid = iosize; 3641 3642 /* 3643 * cleanup bogus pages, restoring the originals. Since 3644 * the originals should still be wired, we don't have 3645 * to worry about interrupt/freeing races destroying 3646 * the VM object association. 3647 */ 3648 m = bp->b_xio.xio_pages[i]; 3649 if (m == bogus_page) { 3650 bogusflag = 1; 3651 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3652 if (m == NULL) 3653 panic("biodone: page disappeared"); 3654 bp->b_xio.xio_pages[i] = m; 3655 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3656 bp->b_xio.xio_pages, bp->b_xio.xio_npages); 3657 } 3658 #if defined(VFS_BIO_DEBUG) 3659 if (OFF_TO_IDX(foff) != m->pindex) { 3660 kprintf("biodone: foff(%lu)/m->pindex(%ld) " 3661 "mismatch\n", 3662 (unsigned long)foff, (long)m->pindex); 3663 } 3664 #endif 3665 3666 /* 3667 * In the write case, the valid and clean bits are 3668 * already changed correctly (see bdwrite()), so we 3669 * only need to do this here in the read case. 3670 */ 3671 if (cmd == BUF_CMD_READ && !bogusflag && resid > 0) { 3672 vfs_clean_one_page(bp, i, m); 3673 } 3674 vm_page_flag_clear(m, PG_ZERO); 3675 3676 /* 3677 * when debugging new filesystems or buffer I/O 3678 * methods, this is the most common error that pops 3679 * up. if you see this, you have not set the page 3680 * busy flag correctly!!! 3681 */ 3682 if (m->busy == 0) { 3683 kprintf("biodone: page busy < 0, " 3684 "pindex: %d, foff: 0x(%x,%x), " 3685 "resid: %d, index: %d\n", 3686 (int) m->pindex, (int)(foff >> 32), 3687 (int) foff & 0xffffffff, resid, i); 3688 if (!vn_isdisk(vp, NULL)) 3689 kprintf(" iosize: %ld, loffset: %lld, " 3690 "flags: 0x%08x, npages: %d\n", 3691 bp->b_vp->v_mount->mnt_stat.f_iosize, 3692 (long long)bp->b_loffset, 3693 bp->b_flags, bp->b_xio.xio_npages); 3694 else 3695 kprintf(" VDEV, loffset: %lld, flags: 0x%08x, npages: %d\n", 3696 (long long)bp->b_loffset, 3697 bp->b_flags, bp->b_xio.xio_npages); 3698 kprintf(" valid: 0x%x, dirty: 0x%x, wired: %d\n", 3699 m->valid, m->dirty, m->wire_count); 3700 panic("biodone: page busy < 0"); 3701 } 3702 vm_page_io_finish(m); 3703 vm_object_pip_subtract(obj, 1); 3704 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3705 iosize -= resid; 3706 } 3707 if (obj) 3708 vm_object_pip_wakeupn(obj, 0); 3709 rel_mplock(); 3710 crit_exit(); 3711 } 3712 3713 /* 3714 * Finish up by releasing the buffer. There are no more synchronous 3715 * or asynchronous completions, those were handled by bio_done 3716 * callbacks. 3717 */ 3718 if (elseit) { 3719 if (bp->b_flags & (B_NOCACHE|B_INVAL|B_ERROR|B_RELBUF)) 3720 brelse(bp); 3721 else 3722 bqrelse(bp); 3723 } 3724 } 3725 3726 /* 3727 * Normal biodone. 3728 */ 3729 void 3730 biodone(struct bio *bio) 3731 { 3732 struct buf *bp = bio->bio_buf; 3733 3734 runningbufwakeup(bp); 3735 3736 /* 3737 * Run up the chain of BIO's. Leave b_cmd intact for the duration. 3738 */ 3739 while (bio) { 3740 biodone_t *done_func; 3741 struct bio_track *track; 3742 3743 /* 3744 * BIO tracking. Most but not all BIOs are tracked. 3745 */ 3746 if ((track = bio->bio_track) != NULL) { 3747 bio_track_rel(track); 3748 bio->bio_track = NULL; 3749 } 3750 3751 /* 3752 * A bio_done function terminates the loop. The function 3753 * will be responsible for any further chaining and/or 3754 * buffer management. 3755 * 3756 * WARNING! The done function can deallocate the buffer! 3757 */ 3758 if ((done_func = bio->bio_done) != NULL) { 3759 bio->bio_done = NULL; 3760 done_func(bio); 3761 return; 3762 } 3763 bio = bio->bio_prev; 3764 } 3765 3766 /* 3767 * If we've run out of bio's do normal [a]synchronous completion. 3768 */ 3769 bpdone(bp, 1); 3770 } 3771 3772 /* 3773 * Synchronous biodone - this terminates a synchronous BIO. 3774 * 3775 * bpdone() is called with elseit=FALSE, leaving the buffer completed 3776 * but still locked. The caller must brelse() the buffer after waiting 3777 * for completion. 3778 */ 3779 void 3780 biodone_sync(struct bio *bio) 3781 { 3782 struct buf *bp = bio->bio_buf; 3783 int flags; 3784 int nflags; 3785 3786 KKASSERT(bio == &bp->b_bio1); 3787 bpdone(bp, 0); 3788 3789 for (;;) { 3790 flags = bio->bio_flags; 3791 nflags = (flags | BIO_DONE) & ~BIO_WANT; 3792 3793 if (atomic_cmpset_int(&bio->bio_flags, flags, nflags)) { 3794 if (flags & BIO_WANT) 3795 wakeup(bio); 3796 break; 3797 } 3798 } 3799 } 3800 3801 /* 3802 * vfs_unbusy_pages: 3803 * 3804 * This routine is called in lieu of iodone in the case of 3805 * incomplete I/O. This keeps the busy status for pages 3806 * consistant. 3807 */ 3808 void 3809 vfs_unbusy_pages(struct buf *bp) 3810 { 3811 int i; 3812 3813 runningbufwakeup(bp); 3814 if (bp->b_flags & B_VMIO) { 3815 struct vnode *vp = bp->b_vp; 3816 vm_object_t obj; 3817 3818 obj = vp->v_object; 3819 3820 for (i = 0; i < bp->b_xio.xio_npages; i++) { 3821 vm_page_t m = bp->b_xio.xio_pages[i]; 3822 3823 /* 3824 * When restoring bogus changes the original pages 3825 * should still be wired, so we are in no danger of 3826 * losing the object association and do not need 3827 * critical section protection particularly. 3828 */ 3829 if (m == bogus_page) { 3830 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_loffset) + i); 3831 if (!m) { 3832 panic("vfs_unbusy_pages: page missing"); 3833 } 3834 bp->b_xio.xio_pages[i] = m; 3835 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3836 bp->b_xio.xio_pages, bp->b_xio.xio_npages); 3837 } 3838 vm_object_pip_subtract(obj, 1); 3839 vm_page_flag_clear(m, PG_ZERO); 3840 vm_page_io_finish(m); 3841 } 3842 vm_object_pip_wakeupn(obj, 0); 3843 } 3844 } 3845 3846 /* 3847 * vfs_busy_pages: 3848 * 3849 * This routine is called before a device strategy routine. 3850 * It is used to tell the VM system that paging I/O is in 3851 * progress, and treat the pages associated with the buffer 3852 * almost as being PG_BUSY. Also the object 'paging_in_progress' 3853 * flag is handled to make sure that the object doesn't become 3854 * inconsistant. 3855 * 3856 * Since I/O has not been initiated yet, certain buffer flags 3857 * such as B_ERROR or B_INVAL may be in an inconsistant state 3858 * and should be ignored. 3859 */ 3860 void 3861 vfs_busy_pages(struct vnode *vp, struct buf *bp) 3862 { 3863 int i, bogus; 3864 struct lwp *lp = curthread->td_lwp; 3865 3866 /* 3867 * The buffer's I/O command must already be set. If reading, 3868 * B_CACHE must be 0 (double check against callers only doing 3869 * I/O when B_CACHE is 0). 3870 */ 3871 KKASSERT(bp->b_cmd != BUF_CMD_DONE); 3872 KKASSERT(bp->b_cmd == BUF_CMD_WRITE || (bp->b_flags & B_CACHE) == 0); 3873 3874 if (bp->b_flags & B_VMIO) { 3875 vm_object_t obj; 3876 3877 obj = vp->v_object; 3878 KASSERT(bp->b_loffset != NOOFFSET, 3879 ("vfs_busy_pages: no buffer offset")); 3880 3881 /* 3882 * Loop until none of the pages are busy. 3883 */ 3884 retry: 3885 for (i = 0; i < bp->b_xio.xio_npages; i++) { 3886 vm_page_t m = bp->b_xio.xio_pages[i]; 3887 3888 if (vm_page_sleep_busy(m, FALSE, "vbpage")) 3889 goto retry; 3890 } 3891 3892 /* 3893 * Setup for I/O, soft-busy the page right now because 3894 * the next loop may block. 3895 */ 3896 for (i = 0; i < bp->b_xio.xio_npages; i++) { 3897 vm_page_t m = bp->b_xio.xio_pages[i]; 3898 3899 vm_page_flag_clear(m, PG_ZERO); 3900 if ((bp->b_flags & B_CLUSTER) == 0) { 3901 vm_object_pip_add(obj, 1); 3902 vm_page_io_start(m); 3903 } 3904 } 3905 3906 /* 3907 * Adjust protections for I/O and do bogus-page mapping. 3908 * Assume that vm_page_protect() can block (it can block 3909 * if VM_PROT_NONE, don't take any chances regardless). 3910 * 3911 * In particular note that for writes we must incorporate 3912 * page dirtyness from the VM system into the buffer's 3913 * dirty range. 3914 * 3915 * For reads we theoretically must incorporate page dirtyness 3916 * from the VM system to determine if the page needs bogus 3917 * replacement, but we shortcut the test by simply checking 3918 * that all m->valid bits are set, indicating that the page 3919 * is fully valid and does not need to be re-read. For any 3920 * VM system dirtyness the page will also be fully valid 3921 * since it was mapped at one point. 3922 */ 3923 bogus = 0; 3924 for (i = 0; i < bp->b_xio.xio_npages; i++) { 3925 vm_page_t m = bp->b_xio.xio_pages[i]; 3926 3927 vm_page_flag_clear(m, PG_ZERO); /* XXX */ 3928 if (bp->b_cmd == BUF_CMD_WRITE) { 3929 /* 3930 * When readying a vnode-backed buffer for 3931 * a write we must zero-fill any invalid 3932 * portions of the backing VM pages, mark 3933 * it valid and clear related dirty bits. 3934 * 3935 * vfs_clean_one_page() incorporates any 3936 * VM dirtyness and updates the b_dirtyoff 3937 * range (after we've made the page RO). 3938 * 3939 * It is also expected that the pmap modified 3940 * bit has already been cleared by the 3941 * vm_page_protect(). We may not be able 3942 * to clear all dirty bits for a page if it 3943 * was also memory mapped (NFS). 3944 * 3945 * Finally be sure to unassign any swap-cache 3946 * backing store as it is now stale. 3947 */ 3948 vm_page_protect(m, VM_PROT_READ); 3949 vfs_clean_one_page(bp, i, m); 3950 swap_pager_unswapped(m); 3951 } else if (m->valid == VM_PAGE_BITS_ALL) { 3952 /* 3953 * When readying a vnode-backed buffer for 3954 * read we must replace any dirty pages with 3955 * a bogus page so dirty data is not destroyed 3956 * when filling gaps. 3957 * 3958 * To avoid testing whether the page is 3959 * dirty we instead test that the page was 3960 * at some point mapped (m->valid fully 3961 * valid) with the understanding that 3962 * this also covers the dirty case. 3963 */ 3964 bp->b_xio.xio_pages[i] = bogus_page; 3965 bogus++; 3966 } else if (m->valid & m->dirty) { 3967 /* 3968 * This case should not occur as partial 3969 * dirtyment can only happen if the buffer 3970 * is B_CACHE, and this code is not entered 3971 * if the buffer is B_CACHE. 3972 */ 3973 kprintf("Warning: vfs_busy_pages - page not " 3974 "fully valid! loff=%jx bpf=%08x " 3975 "idx=%d val=%02x dir=%02x\n", 3976 (intmax_t)bp->b_loffset, bp->b_flags, 3977 i, m->valid, m->dirty); 3978 vm_page_protect(m, VM_PROT_NONE); 3979 } else { 3980 /* 3981 * The page is not valid and can be made 3982 * part of the read. 3983 */ 3984 vm_page_protect(m, VM_PROT_NONE); 3985 } 3986 } 3987 if (bogus) { 3988 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3989 bp->b_xio.xio_pages, bp->b_xio.xio_npages); 3990 } 3991 } 3992 3993 /* 3994 * This is the easiest place to put the process accounting for the I/O 3995 * for now. 3996 */ 3997 if (lp != NULL) { 3998 if (bp->b_cmd == BUF_CMD_READ) 3999 lp->lwp_ru.ru_inblock++; 4000 else 4001 lp->lwp_ru.ru_oublock++; 4002 } 4003 } 4004 4005 /* 4006 * vfs_clean_pages: 4007 * 4008 * Tell the VM system that the pages associated with this buffer 4009 * are clean. This is used for delayed writes where the data is 4010 * going to go to disk eventually without additional VM intevention. 4011 * 4012 * Note that while we only really need to clean through to b_bcount, we 4013 * just go ahead and clean through to b_bufsize. 4014 */ 4015 static void 4016 vfs_clean_pages(struct buf *bp) 4017 { 4018 vm_page_t m; 4019 int i; 4020 4021 if ((bp->b_flags & B_VMIO) == 0) 4022 return; 4023 4024 KASSERT(bp->b_loffset != NOOFFSET, 4025 ("vfs_clean_pages: no buffer offset")); 4026 4027 for (i = 0; i < bp->b_xio.xio_npages; i++) { 4028 m = bp->b_xio.xio_pages[i]; 4029 vfs_clean_one_page(bp, i, m); 4030 } 4031 } 4032 4033 /* 4034 * vfs_clean_one_page: 4035 * 4036 * Set the valid bits and clear the dirty bits in a page within a 4037 * buffer. The range is restricted to the buffer's size and the 4038 * buffer's logical offset might index into the first page. 4039 * 4040 * The caller has busied or soft-busied the page and it is not mapped, 4041 * test and incorporate the dirty bits into b_dirtyoff/end before 4042 * clearing them. Note that we need to clear the pmap modified bits 4043 * after determining the the page was dirty, vm_page_set_validclean() 4044 * does not do it for us. 4045 * 4046 * This routine is typically called after a read completes (dirty should 4047 * be zero in that case as we are not called on bogus-replace pages), 4048 * or before a write is initiated. 4049 */ 4050 static void 4051 vfs_clean_one_page(struct buf *bp, int pageno, vm_page_t m) 4052 { 4053 int bcount; 4054 int xoff; 4055 int soff; 4056 int eoff; 4057 4058 /* 4059 * Calculate offset range within the page but relative to buffer's 4060 * loffset. loffset might be offset into the first page. 4061 */ 4062 xoff = (int)bp->b_loffset & PAGE_MASK; /* loffset offset into pg 0 */ 4063 bcount = bp->b_bcount + xoff; /* offset adjusted */ 4064 4065 if (pageno == 0) { 4066 soff = xoff; 4067 eoff = PAGE_SIZE; 4068 } else { 4069 soff = (pageno << PAGE_SHIFT); 4070 eoff = soff + PAGE_SIZE; 4071 } 4072 if (eoff > bcount) 4073 eoff = bcount; 4074 if (soff >= eoff) 4075 return; 4076 4077 /* 4078 * Test dirty bits and adjust b_dirtyoff/end. 4079 * 4080 * If dirty pages are incorporated into the bp any prior 4081 * B_NEEDCOMMIT state (NFS) must be cleared because the 4082 * caller has not taken into account the new dirty data. 4083 * 4084 * If the page was memory mapped the dirty bits might go beyond the 4085 * end of the buffer, but we can't really make the assumption that 4086 * a file EOF straddles the buffer (even though this is the case for 4087 * NFS if B_NEEDCOMMIT is also set). So for the purposes of clearing 4088 * B_NEEDCOMMIT we only test the dirty bits covered by the buffer. 4089 * This also saves some console spam. 4090 * 4091 * When clearing B_NEEDCOMMIT we must also clear B_CLUSTEROK, 4092 * NFS can handle huge commits but not huge writes. 4093 */ 4094 vm_page_test_dirty(m); 4095 if (m->dirty) { 4096 if ((bp->b_flags & B_NEEDCOMMIT) && 4097 (m->dirty & vm_page_bits(soff & PAGE_MASK, eoff - soff))) { 4098 if (debug_commit) 4099 kprintf("Warning: vfs_clean_one_page: bp %p " 4100 "loff=%jx,%d flgs=%08x clr B_NEEDCOMMIT" 4101 " cmd %d vd %02x/%02x x/s/e %d %d %d " 4102 "doff/end %d %d\n", 4103 bp, (intmax_t)bp->b_loffset, bp->b_bcount, 4104 bp->b_flags, bp->b_cmd, 4105 m->valid, m->dirty, xoff, soff, eoff, 4106 bp->b_dirtyoff, bp->b_dirtyend); 4107 bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK); 4108 if (debug_commit) 4109 print_backtrace(-1); 4110 } 4111 /* 4112 * Only clear the pmap modified bits if ALL the dirty bits 4113 * are set, otherwise the system might mis-clear portions 4114 * of a page. 4115 */ 4116 if (m->dirty == VM_PAGE_BITS_ALL && 4117 (bp->b_flags & B_NEEDCOMMIT) == 0) { 4118 pmap_clear_modify(m); 4119 } 4120 if (bp->b_dirtyoff > soff - xoff) 4121 bp->b_dirtyoff = soff - xoff; 4122 if (bp->b_dirtyend < eoff - xoff) 4123 bp->b_dirtyend = eoff - xoff; 4124 } 4125 4126 /* 4127 * Set related valid bits, clear related dirty bits. 4128 * Does not mess with the pmap modified bit. 4129 * 4130 * WARNING! We cannot just clear all of m->dirty here as the 4131 * buffer cache buffers may use a DEV_BSIZE'd aligned 4132 * block size, or have an odd size (e.g. NFS at file EOF). 4133 * The putpages code can clear m->dirty to 0. 4134 * 4135 * If a VOP_WRITE generates a buffer cache buffer which 4136 * covers the same space as mapped writable pages the 4137 * buffer flush might not be able to clear all the dirty 4138 * bits and still require a putpages from the VM system 4139 * to finish it off. 4140 */ 4141 vm_page_set_validclean(m, soff & PAGE_MASK, eoff - soff); 4142 } 4143 4144 /* 4145 * Similar to vfs_clean_one_page() but sets the bits to valid and dirty. 4146 * The page data is assumed to be valid (there is no zeroing here). 4147 */ 4148 static void 4149 vfs_dirty_one_page(struct buf *bp, int pageno, vm_page_t m) 4150 { 4151 int bcount; 4152 int xoff; 4153 int soff; 4154 int eoff; 4155 4156 /* 4157 * Calculate offset range within the page but relative to buffer's 4158 * loffset. loffset might be offset into the first page. 4159 */ 4160 xoff = (int)bp->b_loffset & PAGE_MASK; /* loffset offset into pg 0 */ 4161 bcount = bp->b_bcount + xoff; /* offset adjusted */ 4162 4163 if (pageno == 0) { 4164 soff = xoff; 4165 eoff = PAGE_SIZE; 4166 } else { 4167 soff = (pageno << PAGE_SHIFT); 4168 eoff = soff + PAGE_SIZE; 4169 } 4170 if (eoff > bcount) 4171 eoff = bcount; 4172 if (soff >= eoff) 4173 return; 4174 vm_page_set_validdirty(m, soff & PAGE_MASK, eoff - soff); 4175 } 4176 4177 /* 4178 * vfs_bio_clrbuf: 4179 * 4180 * Clear a buffer. This routine essentially fakes an I/O, so we need 4181 * to clear B_ERROR and B_INVAL. 4182 * 4183 * Note that while we only theoretically need to clear through b_bcount, 4184 * we go ahead and clear through b_bufsize. 4185 */ 4186 4187 void 4188 vfs_bio_clrbuf(struct buf *bp) 4189 { 4190 int i, mask = 0; 4191 caddr_t sa, ea; 4192 if ((bp->b_flags & (B_VMIO | B_MALLOC)) == B_VMIO) { 4193 bp->b_flags &= ~(B_INVAL | B_EINTR | B_ERROR); 4194 if ((bp->b_xio.xio_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 4195 (bp->b_loffset & PAGE_MASK) == 0) { 4196 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 4197 if ((bp->b_xio.xio_pages[0]->valid & mask) == mask) { 4198 bp->b_resid = 0; 4199 return; 4200 } 4201 if (((bp->b_xio.xio_pages[0]->flags & PG_ZERO) == 0) && 4202 ((bp->b_xio.xio_pages[0]->valid & mask) == 0)) { 4203 bzero(bp->b_data, bp->b_bufsize); 4204 bp->b_xio.xio_pages[0]->valid |= mask; 4205 bp->b_resid = 0; 4206 return; 4207 } 4208 } 4209 sa = bp->b_data; 4210 for(i=0;i<bp->b_xio.xio_npages;i++,sa=ea) { 4211 int j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; 4212 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); 4213 ea = (caddr_t)(vm_offset_t)ulmin( 4214 (u_long)(vm_offset_t)ea, 4215 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); 4216 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 4217 if ((bp->b_xio.xio_pages[i]->valid & mask) == mask) 4218 continue; 4219 if ((bp->b_xio.xio_pages[i]->valid & mask) == 0) { 4220 if ((bp->b_xio.xio_pages[i]->flags & PG_ZERO) == 0) { 4221 bzero(sa, ea - sa); 4222 } 4223 } else { 4224 for (; sa < ea; sa += DEV_BSIZE, j++) { 4225 if (((bp->b_xio.xio_pages[i]->flags & PG_ZERO) == 0) && 4226 (bp->b_xio.xio_pages[i]->valid & (1<<j)) == 0) 4227 bzero(sa, DEV_BSIZE); 4228 } 4229 } 4230 bp->b_xio.xio_pages[i]->valid |= mask; 4231 vm_page_flag_clear(bp->b_xio.xio_pages[i], PG_ZERO); 4232 } 4233 bp->b_resid = 0; 4234 } else { 4235 clrbuf(bp); 4236 } 4237 } 4238 4239 /* 4240 * vm_hold_load_pages: 4241 * 4242 * Load pages into the buffer's address space. The pages are 4243 * allocated from the kernel object in order to reduce interference 4244 * with the any VM paging I/O activity. The range of loaded 4245 * pages will be wired. 4246 * 4247 * If a page cannot be allocated, the 'pagedaemon' is woken up to 4248 * retrieve the full range (to - from) of pages. 4249 * 4250 */ 4251 void 4252 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4253 { 4254 vm_offset_t pg; 4255 vm_page_t p; 4256 int index; 4257 4258 to = round_page(to); 4259 from = round_page(from); 4260 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4261 4262 pg = from; 4263 while (pg < to) { 4264 /* 4265 * Note: must allocate system pages since blocking here 4266 * could intefere with paging I/O, no matter which 4267 * process we are. 4268 */ 4269 p = bio_page_alloc(&kernel_object, pg >> PAGE_SHIFT, 4270 (vm_pindex_t)((to - pg) >> PAGE_SHIFT)); 4271 if (p) { 4272 vm_page_wire(p); 4273 p->valid = VM_PAGE_BITS_ALL; 4274 vm_page_flag_clear(p, PG_ZERO); 4275 pmap_kenter(pg, VM_PAGE_TO_PHYS(p)); 4276 bp->b_xio.xio_pages[index] = p; 4277 vm_page_wakeup(p); 4278 4279 pg += PAGE_SIZE; 4280 ++index; 4281 } 4282 } 4283 bp->b_xio.xio_npages = index; 4284 } 4285 4286 /* 4287 * Allocate pages for a buffer cache buffer. 4288 * 4289 * Under extremely severe memory conditions even allocating out of the 4290 * system reserve can fail. If this occurs we must allocate out of the 4291 * interrupt reserve to avoid a deadlock with the pageout daemon. 4292 * 4293 * The pageout daemon can run (putpages -> VOP_WRITE -> getblk -> allocbuf). 4294 * If the buffer cache's vm_page_alloc() fails a vm_wait() can deadlock 4295 * against the pageout daemon if pages are not freed from other sources. 4296 */ 4297 static 4298 vm_page_t 4299 bio_page_alloc(vm_object_t obj, vm_pindex_t pg, int deficit) 4300 { 4301 vm_page_t p; 4302 4303 /* 4304 * Try a normal allocation, allow use of system reserve. 4305 */ 4306 p = vm_page_alloc(obj, pg, VM_ALLOC_NORMAL | VM_ALLOC_SYSTEM); 4307 if (p) 4308 return(p); 4309 4310 /* 4311 * The normal allocation failed and we clearly have a page 4312 * deficit. Try to reclaim some clean VM pages directly 4313 * from the buffer cache. 4314 */ 4315 vm_pageout_deficit += deficit; 4316 recoverbufpages(); 4317 4318 /* 4319 * We may have blocked, the caller will know what to do if the 4320 * page now exists. 4321 */ 4322 if (vm_page_lookup(obj, pg)) 4323 return(NULL); 4324 4325 /* 4326 * Allocate and allow use of the interrupt reserve. 4327 * 4328 * If after all that we still can't allocate a VM page we are 4329 * in real trouble, but we slog on anyway hoping that the system 4330 * won't deadlock. 4331 */ 4332 p = vm_page_alloc(obj, pg, VM_ALLOC_NORMAL | VM_ALLOC_SYSTEM | 4333 VM_ALLOC_INTERRUPT); 4334 if (p) { 4335 if (vm_page_count_severe()) { 4336 kprintf("bio_page_alloc: WARNING emergency page " 4337 "allocation\n"); 4338 vm_wait(hz / 20); 4339 } 4340 } else { 4341 kprintf("bio_page_alloc: WARNING emergency page " 4342 "allocation failed\n"); 4343 vm_wait(hz * 5); 4344 } 4345 return(p); 4346 } 4347 4348 /* 4349 * vm_hold_free_pages: 4350 * 4351 * Return pages associated with the buffer back to the VM system. 4352 * 4353 * The range of pages underlying the buffer's address space will 4354 * be unmapped and un-wired. 4355 */ 4356 void 4357 vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4358 { 4359 vm_offset_t pg; 4360 vm_page_t p; 4361 int index, newnpages; 4362 4363 from = round_page(from); 4364 to = round_page(to); 4365 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4366 newnpages = index; 4367 4368 lwkt_gettoken(&vm_token); 4369 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 4370 p = bp->b_xio.xio_pages[index]; 4371 if (p && (index < bp->b_xio.xio_npages)) { 4372 if (p->busy) { 4373 kprintf("vm_hold_free_pages: doffset: %lld, " 4374 "loffset: %lld\n", 4375 (long long)bp->b_bio2.bio_offset, 4376 (long long)bp->b_loffset); 4377 } 4378 bp->b_xio.xio_pages[index] = NULL; 4379 pmap_kremove(pg); 4380 vm_page_busy(p); 4381 vm_page_unwire(p, 0); 4382 vm_page_free(p); 4383 } 4384 } 4385 bp->b_xio.xio_npages = newnpages; 4386 lwkt_reltoken(&vm_token); 4387 } 4388 4389 /* 4390 * vmapbuf: 4391 * 4392 * Map a user buffer into KVM via a pbuf. On return the buffer's 4393 * b_data, b_bufsize, and b_bcount will be set, and its XIO page array 4394 * initialized. 4395 */ 4396 int 4397 vmapbuf(struct buf *bp, caddr_t udata, int bytes) 4398 { 4399 caddr_t addr; 4400 vm_offset_t va; 4401 vm_page_t m; 4402 int vmprot; 4403 int error; 4404 int pidx; 4405 int i; 4406 4407 /* 4408 * bp had better have a command and it better be a pbuf. 4409 */ 4410 KKASSERT(bp->b_cmd != BUF_CMD_DONE); 4411 KKASSERT(bp->b_flags & B_PAGING); 4412 4413 if (bytes < 0) 4414 return (-1); 4415 4416 /* 4417 * Map the user data into KVM. Mappings have to be page-aligned. 4418 */ 4419 addr = (caddr_t)trunc_page((vm_offset_t)udata); 4420 pidx = 0; 4421 4422 vmprot = VM_PROT_READ; 4423 if (bp->b_cmd == BUF_CMD_READ) 4424 vmprot |= VM_PROT_WRITE; 4425 4426 while (addr < udata + bytes) { 4427 /* 4428 * Do the vm_fault if needed; do the copy-on-write thing 4429 * when reading stuff off device into memory. 4430 * 4431 * vm_fault_page*() returns a held VM page. 4432 */ 4433 va = (addr >= udata) ? (vm_offset_t)addr : (vm_offset_t)udata; 4434 va = trunc_page(va); 4435 4436 m = vm_fault_page_quick(va, vmprot, &error); 4437 if (m == NULL) { 4438 for (i = 0; i < pidx; ++i) { 4439 vm_page_unhold(bp->b_xio.xio_pages[i]); 4440 bp->b_xio.xio_pages[i] = NULL; 4441 } 4442 return(-1); 4443 } 4444 bp->b_xio.xio_pages[pidx] = m; 4445 addr += PAGE_SIZE; 4446 ++pidx; 4447 } 4448 4449 /* 4450 * Map the page array and set the buffer fields to point to 4451 * the mapped data buffer. 4452 */ 4453 if (pidx > btoc(MAXPHYS)) 4454 panic("vmapbuf: mapped more than MAXPHYS"); 4455 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_xio.xio_pages, pidx); 4456 4457 bp->b_xio.xio_npages = pidx; 4458 bp->b_data = bp->b_kvabase + ((int)(intptr_t)udata & PAGE_MASK); 4459 bp->b_bcount = bytes; 4460 bp->b_bufsize = bytes; 4461 return(0); 4462 } 4463 4464 /* 4465 * vunmapbuf: 4466 * 4467 * Free the io map PTEs associated with this IO operation. 4468 * We also invalidate the TLB entries and restore the original b_addr. 4469 */ 4470 void 4471 vunmapbuf(struct buf *bp) 4472 { 4473 int pidx; 4474 int npages; 4475 4476 KKASSERT(bp->b_flags & B_PAGING); 4477 4478 npages = bp->b_xio.xio_npages; 4479 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 4480 for (pidx = 0; pidx < npages; ++pidx) { 4481 vm_page_unhold(bp->b_xio.xio_pages[pidx]); 4482 bp->b_xio.xio_pages[pidx] = NULL; 4483 } 4484 bp->b_xio.xio_npages = 0; 4485 bp->b_data = bp->b_kvabase; 4486 } 4487 4488 /* 4489 * Scan all buffers in the system and issue the callback. 4490 */ 4491 int 4492 scan_all_buffers(int (*callback)(struct buf *, void *), void *info) 4493 { 4494 int count = 0; 4495 int error; 4496 int n; 4497 4498 for (n = 0; n < nbuf; ++n) { 4499 if ((error = callback(&buf[n], info)) < 0) { 4500 count = error; 4501 break; 4502 } 4503 count += error; 4504 } 4505 return (count); 4506 } 4507 4508 /* 4509 * nestiobuf_iodone: biodone callback for nested buffers and propagate 4510 * completion to the master buffer. 4511 */ 4512 static void 4513 nestiobuf_iodone(struct bio *bio) 4514 { 4515 struct bio *mbio; 4516 struct buf *mbp, *bp; 4517 int error; 4518 int donebytes; 4519 4520 bp = bio->bio_buf; 4521 mbio = bio->bio_caller_info1.ptr; 4522 mbp = mbio->bio_buf; 4523 4524 KKASSERT(bp->b_bcount <= bp->b_bufsize); 4525 KKASSERT(mbp != bp); 4526 4527 error = bp->b_error; 4528 if (bp->b_error == 0 && 4529 (bp->b_bcount < bp->b_bufsize || bp->b_resid > 0)) { 4530 /* 4531 * Not all got transfered, raise an error. We have no way to 4532 * propagate these conditions to mbp. 4533 */ 4534 error = EIO; 4535 } 4536 4537 donebytes = bp->b_bufsize; 4538 4539 relpbuf(bp, NULL); 4540 nestiobuf_done(mbio, donebytes, error); 4541 } 4542 4543 void 4544 nestiobuf_done(struct bio *mbio, int donebytes, int error) 4545 { 4546 struct buf *mbp; 4547 4548 mbp = mbio->bio_buf; 4549 4550 /* If this buf didn't do anything, we are done. */ 4551 if (donebytes == 0) 4552 return; 4553 4554 KKASSERT(mbp->b_resid >= donebytes); 4555 4556 /* If an error occured, propagate it to the master buffer */ 4557 if (error) 4558 mbp->b_error = error; 4559 4560 /* 4561 * Decrement the master buf b_resid according to our donebytes, and 4562 * also check if this is the last missing bit for the whole nestio 4563 * mess to complete. If so, call biodone() on the master buf mbp. 4564 */ 4565 if (atomic_fetchadd_int(&mbp->b_resid, -donebytes) == donebytes) { 4566 biodone(mbio); 4567 } 4568 } 4569 4570 /* 4571 * nestiobuf_setup: setup a "nested" buffer. 4572 * 4573 * => 'mbp' is a "master" buffer which is being divided into sub pieces. 4574 * => 'bp' should be a buffer allocated by getiobuf. 4575 * => 'offset' is a byte offset in the master buffer. 4576 * => 'size' is a size in bytes of this nested buffer. 4577 */ 4578 void 4579 nestiobuf_setup(struct bio *bio, struct buf *bp, int offset, size_t size) 4580 { 4581 struct buf *mbp = bio->bio_buf; 4582 struct vnode *vp = mbp->b_vp; 4583 4584 KKASSERT(mbp->b_bcount >= offset + size); 4585 4586 /* kernel needs to own the lock for it to be released in biodone */ 4587 BUF_KERNPROC(bp); 4588 bp->b_vp = vp; 4589 bp->b_cmd = mbp->b_cmd; 4590 bp->b_bio1.bio_done = nestiobuf_iodone; 4591 bp->b_data = (char *)mbp->b_data + offset; 4592 bp->b_resid = bp->b_bcount = size; 4593 bp->b_bufsize = bp->b_bcount; 4594 4595 bp->b_bio1.bio_track = NULL; 4596 bp->b_bio1.bio_caller_info1.ptr = bio; 4597 } 4598 4599 /* 4600 * print out statistics from the current status of the buffer pool 4601 * this can be toggeled by the system control option debug.syncprt 4602 */ 4603 #ifdef DEBUG 4604 void 4605 vfs_bufstats(void) 4606 { 4607 int i, j, count; 4608 struct buf *bp; 4609 struct bqueues *dp; 4610 int counts[(MAXBSIZE / PAGE_SIZE) + 1]; 4611 static char *bname[3] = { "LOCKED", "LRU", "AGE" }; 4612 4613 for (dp = bufqueues, i = 0; dp < &bufqueues[3]; dp++, i++) { 4614 count = 0; 4615 for (j = 0; j <= MAXBSIZE/PAGE_SIZE; j++) 4616 counts[j] = 0; 4617 crit_enter(); 4618 TAILQ_FOREACH(bp, dp, b_freelist) { 4619 counts[bp->b_bufsize/PAGE_SIZE]++; 4620 count++; 4621 } 4622 crit_exit(); 4623 kprintf("%s: total-%d", bname[i], count); 4624 for (j = 0; j <= MAXBSIZE/PAGE_SIZE; j++) 4625 if (counts[j] != 0) 4626 kprintf(", %d-%d", j * PAGE_SIZE, counts[j]); 4627 kprintf("\n"); 4628 } 4629 } 4630 #endif 4631 4632 #ifdef DDB 4633 4634 DB_SHOW_COMMAND(buffer, db_show_buffer) 4635 { 4636 /* get args */ 4637 struct buf *bp = (struct buf *)addr; 4638 4639 if (!have_addr) { 4640 db_printf("usage: show buffer <addr>\n"); 4641 return; 4642 } 4643 4644 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS); 4645 db_printf("b_cmd = %d\n", bp->b_cmd); 4646 db_printf("b_error = %d, b_bufsize = %d, b_bcount = %d, " 4647 "b_resid = %d\n, b_data = %p, " 4648 "bio_offset(disk) = %lld, bio_offset(phys) = %lld\n", 4649 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 4650 bp->b_data, 4651 (long long)bp->b_bio2.bio_offset, 4652 (long long)(bp->b_bio2.bio_next ? 4653 bp->b_bio2.bio_next->bio_offset : (off_t)-1)); 4654 if (bp->b_xio.xio_npages) { 4655 int i; 4656 db_printf("b_xio.xio_npages = %d, pages(OBJ, IDX, PA): ", 4657 bp->b_xio.xio_npages); 4658 for (i = 0; i < bp->b_xio.xio_npages; i++) { 4659 vm_page_t m; 4660 m = bp->b_xio.xio_pages[i]; 4661 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 4662 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 4663 if ((i + 1) < bp->b_xio.xio_npages) 4664 db_printf(","); 4665 } 4666 db_printf("\n"); 4667 } 4668 } 4669 #endif /* DDB */ 4670