1 /* 2 * Copyright (c) 1994,1997 John S. Dyson 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice immediately at the beginning of the file, without modification, 10 * this list of conditions, and the following disclaimer. 11 * 2. Absolutely no warranty of function or purpose is made by the author 12 * John S. Dyson. 13 * 14 * $FreeBSD: src/sys/kern/vfs_bio.c,v 1.242.2.20 2003/05/28 18:38:10 alc Exp $ 15 */ 16 17 /* 18 * this file contains a new buffer I/O scheme implementing a coherent 19 * VM object and buffer cache scheme. Pains have been taken to make 20 * sure that the performance degradation associated with schemes such 21 * as this is not realized. 22 * 23 * Author: John S. Dyson 24 * Significant help during the development and debugging phases 25 * had been provided by David Greenman, also of the FreeBSD core team. 26 * 27 * see man buf(9) for more info. 28 */ 29 30 #include <sys/param.h> 31 #include <sys/systm.h> 32 #include <sys/buf.h> 33 #include <sys/conf.h> 34 #include <sys/devicestat.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 <vm/vm.h> 49 #include <vm/vm_param.h> 50 #include <vm/vm_kern.h> 51 #include <vm/vm_pageout.h> 52 #include <vm/vm_page.h> 53 #include <vm/vm_object.h> 54 #include <vm/vm_extern.h> 55 #include <vm/vm_map.h> 56 #include <vm/vm_pager.h> 57 #include <vm/swap_pager.h> 58 59 #include <sys/buf2.h> 60 #include <sys/thread2.h> 61 #include <sys/spinlock2.h> 62 #include <sys/mplock2.h> 63 #include <vm/vm_page2.h> 64 65 #include "opt_ddb.h" 66 #ifdef DDB 67 #include <ddb/ddb.h> 68 #endif 69 70 /* 71 * Buffer queues. 72 */ 73 enum bufq_type { 74 BQUEUE_NONE, /* not on any queue */ 75 BQUEUE_LOCKED, /* locked buffers */ 76 BQUEUE_CLEAN, /* non-B_DELWRI buffers */ 77 BQUEUE_DIRTY, /* B_DELWRI buffers */ 78 BQUEUE_DIRTY_HW, /* B_DELWRI buffers - heavy weight */ 79 BQUEUE_EMPTYKVA, /* empty buffer headers with KVA assignment */ 80 BQUEUE_EMPTY, /* empty buffer headers */ 81 82 BUFFER_QUEUES /* number of buffer queues */ 83 }; 84 85 typedef enum bufq_type bufq_type_t; 86 87 #define BD_WAKE_SIZE 16384 88 #define BD_WAKE_MASK (BD_WAKE_SIZE - 1) 89 90 TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES]; 91 static struct spinlock bufqspin = SPINLOCK_INITIALIZER(&bufqspin); 92 static struct spinlock bufcspin = SPINLOCK_INITIALIZER(&bufcspin); 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 long bufspace; /* locked by buffer_map */ 123 long maxbufspace; 124 static long bufmallocspace; /* atomic ops */ 125 long maxbufmallocspace, lobufspace, hibufspace; 126 static int bufreusecnt, bufdefragcnt, buffreekvacnt; 127 static long lorunningspace; 128 static long hirunningspace; 129 static int runningbufreq; /* locked by bufcspin */ 130 static long dirtybufspace; /* locked by bufcspin */ 131 static int dirtybufcount; /* locked by bufcspin */ 132 static long dirtybufspacehw; /* locked by bufcspin */ 133 static int dirtybufcounthw; /* locked by bufcspin */ 134 static long runningbufspace; /* locked by bufcspin */ 135 static int runningbufcount; /* locked by bufcspin */ 136 long lodirtybufspace; 137 long hidirtybufspace; 138 static int getnewbufcalls; 139 static int getnewbufrestarts; 140 static int recoverbufcalls; 141 static int needsbuffer; /* locked by bufcspin */ 142 static int bd_request; /* locked by bufcspin */ 143 static int bd_request_hw; /* locked by bufcspin */ 144 static u_int bd_wake_ary[BD_WAKE_SIZE]; 145 static u_int bd_wake_index; 146 static u_int vm_cycle_point = 40; /* 23-36 will migrate more act->inact */ 147 static int debug_commit; 148 149 static struct thread *bufdaemon_td; 150 static struct thread *bufdaemonhw_td; 151 static u_int lowmempgallocs; 152 static u_int lowmempgfails; 153 154 /* 155 * Sysctls for operational control of the buffer cache. 156 */ 157 SYSCTL_LONG(_vfs, OID_AUTO, lodirtybufspace, CTLFLAG_RW, &lodirtybufspace, 0, 158 "Number of dirty buffers to flush before bufdaemon becomes inactive"); 159 SYSCTL_LONG(_vfs, OID_AUTO, hidirtybufspace, CTLFLAG_RW, &hidirtybufspace, 0, 160 "High watermark used to trigger explicit flushing of dirty buffers"); 161 SYSCTL_LONG(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0, 162 "Minimum amount of buffer space required for active I/O"); 163 SYSCTL_LONG(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0, 164 "Maximum amount of buffer space to usable for active I/O"); 165 SYSCTL_UINT(_vfs, OID_AUTO, lowmempgallocs, CTLFLAG_RW, &lowmempgallocs, 0, 166 "Page allocations done during periods of very low free memory"); 167 SYSCTL_UINT(_vfs, OID_AUTO, lowmempgfails, CTLFLAG_RW, &lowmempgfails, 0, 168 "Page allocations which failed during periods of very low free memory"); 169 SYSCTL_UINT(_vfs, OID_AUTO, vm_cycle_point, CTLFLAG_RW, &vm_cycle_point, 0, 170 "Recycle pages to active or inactive queue transition pt 0-64"); 171 /* 172 * Sysctls determining current state of the buffer cache. 173 */ 174 SYSCTL_INT(_vfs, OID_AUTO, nbuf, CTLFLAG_RD, &nbuf, 0, 175 "Total number of buffers in buffer cache"); 176 SYSCTL_LONG(_vfs, OID_AUTO, dirtybufspace, CTLFLAG_RD, &dirtybufspace, 0, 177 "Pending bytes of dirty buffers (all)"); 178 SYSCTL_LONG(_vfs, OID_AUTO, dirtybufspacehw, CTLFLAG_RD, &dirtybufspacehw, 0, 179 "Pending bytes of dirty buffers (heavy weight)"); 180 SYSCTL_INT(_vfs, OID_AUTO, dirtybufcount, CTLFLAG_RD, &dirtybufcount, 0, 181 "Pending number of dirty buffers"); 182 SYSCTL_INT(_vfs, OID_AUTO, dirtybufcounthw, CTLFLAG_RD, &dirtybufcounthw, 0, 183 "Pending number of dirty buffers (heavy weight)"); 184 SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 185 "I/O bytes currently in progress due to asynchronous writes"); 186 SYSCTL_INT(_vfs, OID_AUTO, runningbufcount, CTLFLAG_RD, &runningbufcount, 0, 187 "I/O buffers currently in progress due to asynchronous writes"); 188 SYSCTL_LONG(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0, 189 "Hard limit on maximum amount of memory usable for buffer space"); 190 SYSCTL_LONG(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0, 191 "Soft limit on maximum amount of memory usable for buffer space"); 192 SYSCTL_LONG(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0, 193 "Minimum amount of memory to reserve for system buffer space"); 194 SYSCTL_LONG(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, 195 "Amount of memory available for buffers"); 196 SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RD, &maxbufmallocspace, 197 0, "Maximum amount of memory reserved for buffers using malloc"); 198 SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 199 "Amount of memory left for buffers using malloc-scheme"); 200 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RD, &getnewbufcalls, 0, 201 "New buffer header acquisition requests"); 202 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RD, &getnewbufrestarts, 203 0, "New buffer header acquisition restarts"); 204 SYSCTL_INT(_vfs, OID_AUTO, recoverbufcalls, CTLFLAG_RD, &recoverbufcalls, 0, 205 "Recover VM space in an emergency"); 206 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RD, &bufdefragcnt, 0, 207 "Buffer acquisition restarts due to fragmented buffer map"); 208 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RD, &buffreekvacnt, 0, 209 "Amount of time KVA space was deallocated in an arbitrary buffer"); 210 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RD, &bufreusecnt, 0, 211 "Amount of time buffer re-use operations were successful"); 212 SYSCTL_INT(_vfs, OID_AUTO, debug_commit, CTLFLAG_RW, &debug_commit, 0, ""); 213 SYSCTL_INT(_debug_sizeof, OID_AUTO, buf, CTLFLAG_RD, 0, sizeof(struct buf), 214 "sizeof(struct buf)"); 215 216 char *buf_wmesg = BUF_WMESG; 217 218 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 219 #define VFS_BIO_NEED_UNUSED02 0x02 220 #define VFS_BIO_NEED_UNUSED04 0x04 221 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 222 223 /* 224 * bufspacewakeup: 225 * 226 * Called when buffer space is potentially available for recovery. 227 * getnewbuf() will block on this flag when it is unable to free 228 * sufficient buffer space. Buffer space becomes recoverable when 229 * bp's get placed back in the queues. 230 */ 231 static __inline void 232 bufspacewakeup(void) 233 { 234 /* 235 * If someone is waiting for BUF space, wake them up. Even 236 * though we haven't freed the kva space yet, the waiting 237 * process will be able to now. 238 */ 239 spin_lock(&bufcspin); 240 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) { 241 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE; 242 spin_unlock(&bufcspin); 243 wakeup(&needsbuffer); 244 } else { 245 spin_unlock(&bufcspin); 246 } 247 } 248 249 /* 250 * runningbufwakeup: 251 * 252 * Accounting for I/O in progress. 253 * 254 */ 255 static __inline void 256 runningbufwakeup(struct buf *bp) 257 { 258 long totalspace; 259 long limit; 260 261 if ((totalspace = bp->b_runningbufspace) != 0) { 262 spin_lock(&bufcspin); 263 runningbufspace -= totalspace; 264 --runningbufcount; 265 bp->b_runningbufspace = 0; 266 267 /* 268 * see waitrunningbufspace() for limit test. 269 */ 270 limit = hirunningspace * 3 / 6; 271 if (runningbufreq && runningbufspace <= limit) { 272 runningbufreq = 0; 273 spin_unlock(&bufcspin); 274 wakeup(&runningbufreq); 275 } else { 276 spin_unlock(&bufcspin); 277 } 278 bd_signal(totalspace); 279 } 280 } 281 282 /* 283 * bufcountwakeup: 284 * 285 * Called when a buffer has been added to one of the free queues to 286 * account for the buffer and to wakeup anyone waiting for free buffers. 287 * This typically occurs when large amounts of metadata are being handled 288 * by the buffer cache ( else buffer space runs out first, usually ). 289 * 290 * MPSAFE 291 */ 292 static __inline void 293 bufcountwakeup(void) 294 { 295 spin_lock(&bufcspin); 296 if (needsbuffer) { 297 needsbuffer &= ~VFS_BIO_NEED_ANY; 298 spin_unlock(&bufcspin); 299 wakeup(&needsbuffer); 300 } else { 301 spin_unlock(&bufcspin); 302 } 303 } 304 305 /* 306 * waitrunningbufspace() 307 * 308 * If runningbufspace exceeds 4/6 hirunningspace we block until 309 * runningbufspace drops to 3/6 hirunningspace. We also block if another 310 * thread blocked here in order to be fair, even if runningbufspace 311 * is now lower than the limit. 312 * 313 * The caller may be using this function to block in a tight loop, we 314 * must block while runningbufspace is greater than at least 315 * hirunningspace * 3 / 6. 316 */ 317 void 318 waitrunningbufspace(void) 319 { 320 long limit = hirunningspace * 4 / 6; 321 322 if (runningbufspace > limit || runningbufreq) { 323 spin_lock(&bufcspin); 324 while (runningbufspace > limit || runningbufreq) { 325 runningbufreq = 1; 326 ssleep(&runningbufreq, &bufcspin, 0, "wdrn1", 0); 327 } 328 spin_unlock(&bufcspin); 329 } 330 } 331 332 /* 333 * buf_dirty_count_severe: 334 * 335 * Return true if we have too many dirty buffers. 336 */ 337 int 338 buf_dirty_count_severe(void) 339 { 340 return (runningbufspace + dirtybufspace >= hidirtybufspace || 341 dirtybufcount >= nbuf / 2); 342 } 343 344 /* 345 * Return true if the amount of running I/O is severe and BIOQ should 346 * start bursting. 347 */ 348 int 349 buf_runningbufspace_severe(void) 350 { 351 return (runningbufspace >= hirunningspace * 4 / 6); 352 } 353 354 /* 355 * vfs_buf_test_cache: 356 * 357 * Called when a buffer is extended. This function clears the B_CACHE 358 * bit if the newly extended portion of the buffer does not contain 359 * valid data. 360 * 361 * NOTE! Dirty VM pages are not processed into dirty (B_DELWRI) buffer 362 * cache buffers. The VM pages remain dirty, as someone had mmap()'d 363 * them while a clean buffer was present. 364 */ 365 static __inline__ 366 void 367 vfs_buf_test_cache(struct buf *bp, 368 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 369 vm_page_t m) 370 { 371 if (bp->b_flags & B_CACHE) { 372 int base = (foff + off) & PAGE_MASK; 373 if (vm_page_is_valid(m, base, size) == 0) 374 bp->b_flags &= ~B_CACHE; 375 } 376 } 377 378 /* 379 * bd_speedup() 380 * 381 * Spank the buf_daemon[_hw] if the total dirty buffer space exceeds the 382 * low water mark. 383 * 384 * MPSAFE 385 */ 386 static __inline__ 387 void 388 bd_speedup(void) 389 { 390 if (dirtybufspace < lodirtybufspace && dirtybufcount < nbuf / 2) 391 return; 392 393 if (bd_request == 0 && 394 (dirtybufspace - dirtybufspacehw > lodirtybufspace / 2 || 395 dirtybufcount - dirtybufcounthw >= nbuf / 2)) { 396 spin_lock(&bufcspin); 397 bd_request = 1; 398 spin_unlock(&bufcspin); 399 wakeup(&bd_request); 400 } 401 if (bd_request_hw == 0 && 402 (dirtybufspacehw > lodirtybufspace / 2 || 403 dirtybufcounthw >= nbuf / 2)) { 404 spin_lock(&bufcspin); 405 bd_request_hw = 1; 406 spin_unlock(&bufcspin); 407 wakeup(&bd_request_hw); 408 } 409 } 410 411 /* 412 * bd_heatup() 413 * 414 * Get the buf_daemon heated up when the number of running and dirty 415 * buffers exceeds the mid-point. 416 * 417 * Return the total number of dirty bytes past the second mid point 418 * as a measure of how much excess dirty data there is in the system. 419 * 420 * MPSAFE 421 */ 422 int 423 bd_heatup(void) 424 { 425 long mid1; 426 long mid2; 427 long totalspace; 428 429 mid1 = lodirtybufspace + (hidirtybufspace - lodirtybufspace) / 2; 430 431 totalspace = runningbufspace + dirtybufspace; 432 if (totalspace >= mid1 || dirtybufcount >= nbuf / 2) { 433 bd_speedup(); 434 mid2 = mid1 + (hidirtybufspace - mid1) / 2; 435 if (totalspace >= mid2) 436 return(totalspace - mid2); 437 } 438 return(0); 439 } 440 441 /* 442 * bd_wait() 443 * 444 * Wait for the buffer cache to flush (totalspace) bytes worth of 445 * buffers, then return. 446 * 447 * Regardless this function blocks while the number of dirty buffers 448 * exceeds hidirtybufspace. 449 * 450 * MPSAFE 451 */ 452 void 453 bd_wait(int totalspace) 454 { 455 u_int i; 456 int count; 457 458 if (curthread == bufdaemonhw_td || curthread == bufdaemon_td) 459 return; 460 461 while (totalspace > 0) { 462 bd_heatup(); 463 if (totalspace > runningbufspace + dirtybufspace) 464 totalspace = runningbufspace + dirtybufspace; 465 count = totalspace / BKVASIZE; 466 if (count >= BD_WAKE_SIZE) 467 count = BD_WAKE_SIZE - 1; 468 469 spin_lock(&bufcspin); 470 i = (bd_wake_index + count) & BD_WAKE_MASK; 471 ++bd_wake_ary[i]; 472 473 /* 474 * This is not a strict interlock, so we play a bit loose 475 * with locking access to dirtybufspace* 476 */ 477 tsleep_interlock(&bd_wake_ary[i], 0); 478 spin_unlock(&bufcspin); 479 tsleep(&bd_wake_ary[i], PINTERLOCKED, "flstik", hz); 480 481 totalspace = runningbufspace + dirtybufspace - hidirtybufspace; 482 } 483 } 484 485 /* 486 * bd_signal() 487 * 488 * This function is called whenever runningbufspace or dirtybufspace 489 * is reduced. Track threads waiting for run+dirty buffer I/O 490 * complete. 491 * 492 * MPSAFE 493 */ 494 static void 495 bd_signal(int totalspace) 496 { 497 u_int i; 498 499 if (totalspace > 0) { 500 if (totalspace > BKVASIZE * BD_WAKE_SIZE) 501 totalspace = BKVASIZE * BD_WAKE_SIZE; 502 spin_lock(&bufcspin); 503 while (totalspace > 0) { 504 i = bd_wake_index++; 505 i &= BD_WAKE_MASK; 506 if (bd_wake_ary[i]) { 507 bd_wake_ary[i] = 0; 508 spin_unlock(&bufcspin); 509 wakeup(&bd_wake_ary[i]); 510 spin_lock(&bufcspin); 511 } 512 totalspace -= BKVASIZE; 513 } 514 spin_unlock(&bufcspin); 515 } 516 } 517 518 /* 519 * BIO tracking support routines. 520 * 521 * Release a ref on a bio_track. Wakeup requests are atomically released 522 * along with the last reference so bk_active will never wind up set to 523 * only 0x80000000. 524 * 525 * MPSAFE 526 */ 527 static 528 void 529 bio_track_rel(struct bio_track *track) 530 { 531 int active; 532 int desired; 533 534 /* 535 * Shortcut 536 */ 537 active = track->bk_active; 538 if (active == 1 && atomic_cmpset_int(&track->bk_active, 1, 0)) 539 return; 540 541 /* 542 * Full-on. Note that the wait flag is only atomically released on 543 * the 1->0 count transition. 544 * 545 * We check for a negative count transition using bit 30 since bit 31 546 * has a different meaning. 547 */ 548 for (;;) { 549 desired = (active & 0x7FFFFFFF) - 1; 550 if (desired) 551 desired |= active & 0x80000000; 552 if (atomic_cmpset_int(&track->bk_active, active, desired)) { 553 if (desired & 0x40000000) 554 panic("bio_track_rel: bad count: %p\n", track); 555 if (active & 0x80000000) 556 wakeup(track); 557 break; 558 } 559 active = track->bk_active; 560 } 561 } 562 563 /* 564 * Wait for the tracking count to reach 0. 565 * 566 * Use atomic ops such that the wait flag is only set atomically when 567 * bk_active is non-zero. 568 * 569 * MPSAFE 570 */ 571 int 572 bio_track_wait(struct bio_track *track, int slp_flags, int slp_timo) 573 { 574 int active; 575 int desired; 576 int error; 577 578 /* 579 * Shortcut 580 */ 581 if (track->bk_active == 0) 582 return(0); 583 584 /* 585 * Full-on. Note that the wait flag may only be atomically set if 586 * the active count is non-zero. 587 * 588 * NOTE: We cannot optimize active == desired since a wakeup could 589 * clear active prior to our tsleep_interlock(). 590 */ 591 error = 0; 592 while ((active = track->bk_active) != 0) { 593 cpu_ccfence(); 594 desired = active | 0x80000000; 595 tsleep_interlock(track, slp_flags); 596 if (atomic_cmpset_int(&track->bk_active, active, desired)) { 597 error = tsleep(track, slp_flags | PINTERLOCKED, 598 "trwait", slp_timo); 599 if (error) 600 break; 601 } 602 } 603 return (error); 604 } 605 606 /* 607 * bufinit: 608 * 609 * Load time initialisation of the buffer cache, called from machine 610 * dependant initialization code. 611 */ 612 void 613 bufinit(void) 614 { 615 struct buf *bp; 616 vm_offset_t bogus_offset; 617 int i; 618 619 /* next, make a null set of free lists */ 620 for (i = 0; i < BUFFER_QUEUES; i++) 621 TAILQ_INIT(&bufqueues[i]); 622 623 /* finally, initialize each buffer header and stick on empty q */ 624 for (i = 0; i < nbuf; i++) { 625 bp = &buf[i]; 626 bzero(bp, sizeof *bp); 627 bp->b_flags = B_INVAL; /* we're just an empty header */ 628 bp->b_cmd = BUF_CMD_DONE; 629 bp->b_qindex = BQUEUE_EMPTY; 630 initbufbio(bp); 631 xio_init(&bp->b_xio); 632 buf_dep_init(bp); 633 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_EMPTY], bp, b_freelist); 634 } 635 636 /* 637 * maxbufspace is the absolute maximum amount of buffer space we are 638 * allowed to reserve in KVM and in real terms. The absolute maximum 639 * is nominally used by buf_daemon. hibufspace is the nominal maximum 640 * used by most other processes. The differential is required to 641 * ensure that buf_daemon is able to run when other processes might 642 * be blocked waiting for buffer space. 643 * 644 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 645 * this may result in KVM fragmentation which is not handled optimally 646 * by the system. 647 */ 648 maxbufspace = (long)nbuf * BKVASIZE; 649 hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 650 lobufspace = hibufspace - MAXBSIZE; 651 652 lorunningspace = 512 * 1024; 653 /* hirunningspace -- see below */ 654 655 /* 656 * Limit the amount of malloc memory since it is wired permanently 657 * into the kernel space. Even though this is accounted for in 658 * the buffer allocation, we don't want the malloced region to grow 659 * uncontrolled. The malloc scheme improves memory utilization 660 * significantly on average (small) directories. 661 */ 662 maxbufmallocspace = hibufspace / 20; 663 664 /* 665 * Reduce the chance of a deadlock occuring by limiting the number 666 * of delayed-write dirty buffers we allow to stack up. 667 * 668 * We don't want too much actually queued to the device at once 669 * (XXX this needs to be per-mount!), because the buffers will 670 * wind up locked for a very long period of time while the I/O 671 * drains. 672 */ 673 hidirtybufspace = hibufspace / 2; /* dirty + running */ 674 hirunningspace = hibufspace / 16; /* locked & queued to device */ 675 if (hirunningspace < 1024 * 1024) 676 hirunningspace = 1024 * 1024; 677 678 dirtybufspace = 0; 679 dirtybufspacehw = 0; 680 681 lodirtybufspace = hidirtybufspace / 2; 682 683 /* 684 * Maximum number of async ops initiated per buf_daemon loop. This is 685 * somewhat of a hack at the moment, we really need to limit ourselves 686 * based on the number of bytes of I/O in-transit that were initiated 687 * from buf_daemon. 688 */ 689 690 bogus_offset = kmem_alloc_pageable(&kernel_map, PAGE_SIZE); 691 vm_object_hold(&kernel_object); 692 bogus_page = vm_page_alloc(&kernel_object, 693 (bogus_offset >> PAGE_SHIFT), 694 VM_ALLOC_NORMAL); 695 vm_object_drop(&kernel_object); 696 vmstats.v_wire_count++; 697 698 } 699 700 /* 701 * Initialize the embedded bio structures, typically used by 702 * deprecated code which tries to allocate its own struct bufs. 703 */ 704 void 705 initbufbio(struct buf *bp) 706 { 707 bp->b_bio1.bio_buf = bp; 708 bp->b_bio1.bio_prev = NULL; 709 bp->b_bio1.bio_offset = NOOFFSET; 710 bp->b_bio1.bio_next = &bp->b_bio2; 711 bp->b_bio1.bio_done = NULL; 712 bp->b_bio1.bio_flags = 0; 713 714 bp->b_bio2.bio_buf = bp; 715 bp->b_bio2.bio_prev = &bp->b_bio1; 716 bp->b_bio2.bio_offset = NOOFFSET; 717 bp->b_bio2.bio_next = NULL; 718 bp->b_bio2.bio_done = NULL; 719 bp->b_bio2.bio_flags = 0; 720 721 BUF_LOCKINIT(bp); 722 } 723 724 /* 725 * Reinitialize the embedded bio structures as well as any additional 726 * translation cache layers. 727 */ 728 void 729 reinitbufbio(struct buf *bp) 730 { 731 struct bio *bio; 732 733 for (bio = &bp->b_bio1; bio; bio = bio->bio_next) { 734 bio->bio_done = NULL; 735 bio->bio_offset = NOOFFSET; 736 } 737 } 738 739 /* 740 * Undo the effects of an initbufbio(). 741 */ 742 void 743 uninitbufbio(struct buf *bp) 744 { 745 dsched_exit_buf(bp); 746 BUF_LOCKFREE(bp); 747 } 748 749 /* 750 * Push another BIO layer onto an existing BIO and return it. The new 751 * BIO layer may already exist, holding cached translation data. 752 */ 753 struct bio * 754 push_bio(struct bio *bio) 755 { 756 struct bio *nbio; 757 758 if ((nbio = bio->bio_next) == NULL) { 759 int index = bio - &bio->bio_buf->b_bio_array[0]; 760 if (index >= NBUF_BIO - 1) { 761 panic("push_bio: too many layers bp %p\n", 762 bio->bio_buf); 763 } 764 nbio = &bio->bio_buf->b_bio_array[index + 1]; 765 bio->bio_next = nbio; 766 nbio->bio_prev = bio; 767 nbio->bio_buf = bio->bio_buf; 768 nbio->bio_offset = NOOFFSET; 769 nbio->bio_done = NULL; 770 nbio->bio_next = NULL; 771 } 772 KKASSERT(nbio->bio_done == NULL); 773 return(nbio); 774 } 775 776 /* 777 * Pop a BIO translation layer, returning the previous layer. The 778 * must have been previously pushed. 779 */ 780 struct bio * 781 pop_bio(struct bio *bio) 782 { 783 return(bio->bio_prev); 784 } 785 786 void 787 clearbiocache(struct bio *bio) 788 { 789 while (bio) { 790 bio->bio_offset = NOOFFSET; 791 bio = bio->bio_next; 792 } 793 } 794 795 /* 796 * bfreekva: 797 * 798 * Free the KVA allocation for buffer 'bp'. 799 * 800 * Must be called from a critical section as this is the only locking for 801 * buffer_map. 802 * 803 * Since this call frees up buffer space, we call bufspacewakeup(). 804 * 805 * MPALMOSTSAFE 806 */ 807 static void 808 bfreekva(struct buf *bp) 809 { 810 int count; 811 812 if (bp->b_kvasize) { 813 ++buffreekvacnt; 814 count = vm_map_entry_reserve(MAP_RESERVE_COUNT); 815 vm_map_lock(&buffer_map); 816 bufspace -= bp->b_kvasize; 817 vm_map_delete(&buffer_map, 818 (vm_offset_t) bp->b_kvabase, 819 (vm_offset_t) bp->b_kvabase + bp->b_kvasize, 820 &count 821 ); 822 vm_map_unlock(&buffer_map); 823 vm_map_entry_release(count); 824 bp->b_kvasize = 0; 825 bp->b_kvabase = NULL; 826 bufspacewakeup(); 827 } 828 } 829 830 /* 831 * bremfree: 832 * 833 * Remove the buffer from the appropriate free list. 834 */ 835 static __inline void 836 _bremfree(struct buf *bp) 837 { 838 if (bp->b_qindex != BQUEUE_NONE) { 839 KASSERT(BUF_REFCNTNB(bp) == 1, 840 ("bremfree: bp %p not locked",bp)); 841 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 842 bp->b_qindex = BQUEUE_NONE; 843 } else { 844 if (BUF_REFCNTNB(bp) <= 1) 845 panic("bremfree: removing a buffer not on a queue"); 846 } 847 } 848 849 void 850 bremfree(struct buf *bp) 851 { 852 spin_lock(&bufqspin); 853 _bremfree(bp); 854 spin_unlock(&bufqspin); 855 } 856 857 static void 858 bremfree_locked(struct buf *bp) 859 { 860 _bremfree(bp); 861 } 862 863 /* 864 * This version of bread issues any required I/O asyncnronously and 865 * makes a callback on completion. 866 * 867 * The callback must check whether BIO_DONE is set in the bio and issue 868 * the bpdone(bp, 0) if it isn't. The callback is responsible for clearing 869 * BIO_DONE and disposing of the I/O (bqrelse()ing it). 870 */ 871 void 872 breadcb(struct vnode *vp, off_t loffset, int size, 873 void (*func)(struct bio *), void *arg) 874 { 875 struct buf *bp; 876 877 bp = getblk(vp, loffset, size, 0, 0); 878 879 /* if not found in cache, do some I/O */ 880 if ((bp->b_flags & B_CACHE) == 0) { 881 bp->b_flags &= ~(B_ERROR | B_EINTR | B_INVAL); 882 bp->b_cmd = BUF_CMD_READ; 883 bp->b_bio1.bio_done = func; 884 bp->b_bio1.bio_caller_info1.ptr = arg; 885 vfs_busy_pages(vp, bp); 886 BUF_KERNPROC(bp); 887 vn_strategy(vp, &bp->b_bio1); 888 } else if (func) { 889 /* 890 * Since we are issuing the callback synchronously it cannot 891 * race the BIO_DONE, so no need for atomic ops here. 892 */ 893 /*bp->b_bio1.bio_done = func;*/ 894 bp->b_bio1.bio_caller_info1.ptr = arg; 895 bp->b_bio1.bio_flags |= BIO_DONE; 896 func(&bp->b_bio1); 897 } else { 898 bqrelse(bp); 899 } 900 } 901 902 /* 903 * breadnx() - Terminal function for bread() and breadn(). 904 * 905 * This function will start asynchronous I/O on read-ahead blocks as well 906 * as satisfy the primary request. 907 * 908 * We must clear B_ERROR and B_INVAL prior to initiating I/O. If B_CACHE is 909 * set, the buffer is valid and we do not have to do anything. 910 */ 911 int 912 breadnx(struct vnode *vp, off_t loffset, int size, off_t *raoffset, 913 int *rabsize, int cnt, struct buf **bpp) 914 { 915 struct buf *bp, *rabp; 916 int i; 917 int rv = 0, readwait = 0; 918 919 if (*bpp) 920 bp = *bpp; 921 else 922 *bpp = bp = getblk(vp, loffset, size, 0, 0); 923 924 /* if not found in cache, do some I/O */ 925 if ((bp->b_flags & B_CACHE) == 0) { 926 bp->b_flags &= ~(B_ERROR | B_EINTR | B_INVAL); 927 bp->b_cmd = BUF_CMD_READ; 928 bp->b_bio1.bio_done = biodone_sync; 929 bp->b_bio1.bio_flags |= BIO_SYNC; 930 vfs_busy_pages(vp, bp); 931 vn_strategy(vp, &bp->b_bio1); 932 ++readwait; 933 } 934 935 for (i = 0; i < cnt; i++, raoffset++, rabsize++) { 936 if (inmem(vp, *raoffset)) 937 continue; 938 rabp = getblk(vp, *raoffset, *rabsize, 0, 0); 939 940 if ((rabp->b_flags & B_CACHE) == 0) { 941 rabp->b_flags &= ~(B_ERROR | B_EINTR | B_INVAL); 942 rabp->b_cmd = BUF_CMD_READ; 943 vfs_busy_pages(vp, rabp); 944 BUF_KERNPROC(rabp); 945 vn_strategy(vp, &rabp->b_bio1); 946 } else { 947 brelse(rabp); 948 } 949 } 950 if (readwait) 951 rv = biowait(&bp->b_bio1, "biord"); 952 return (rv); 953 } 954 955 /* 956 * bwrite: 957 * 958 * Synchronous write, waits for completion. 959 * 960 * Write, release buffer on completion. (Done by iodone 961 * if async). Do not bother writing anything if the buffer 962 * is invalid. 963 * 964 * Note that we set B_CACHE here, indicating that buffer is 965 * fully valid and thus cacheable. This is true even of NFS 966 * now so we set it generally. This could be set either here 967 * or in biodone() since the I/O is synchronous. We put it 968 * here. 969 */ 970 int 971 bwrite(struct buf *bp) 972 { 973 int error; 974 975 if (bp->b_flags & B_INVAL) { 976 brelse(bp); 977 return (0); 978 } 979 if (BUF_REFCNTNB(bp) == 0) 980 panic("bwrite: buffer is not busy???"); 981 982 /* Mark the buffer clean */ 983 bundirty(bp); 984 985 bp->b_flags &= ~(B_ERROR | B_EINTR); 986 bp->b_flags |= B_CACHE; 987 bp->b_cmd = BUF_CMD_WRITE; 988 bp->b_bio1.bio_done = biodone_sync; 989 bp->b_bio1.bio_flags |= BIO_SYNC; 990 vfs_busy_pages(bp->b_vp, bp); 991 992 /* 993 * Normal bwrites pipeline writes. NOTE: b_bufsize is only 994 * valid for vnode-backed buffers. 995 */ 996 bsetrunningbufspace(bp, bp->b_bufsize); 997 vn_strategy(bp->b_vp, &bp->b_bio1); 998 error = biowait(&bp->b_bio1, "biows"); 999 brelse(bp); 1000 1001 return (error); 1002 } 1003 1004 /* 1005 * bawrite: 1006 * 1007 * Asynchronous write. Start output on a buffer, but do not wait for 1008 * it to complete. The buffer is released when the output completes. 1009 * 1010 * bwrite() ( or the VOP routine anyway ) is responsible for handling 1011 * B_INVAL buffers. Not us. 1012 */ 1013 void 1014 bawrite(struct buf *bp) 1015 { 1016 if (bp->b_flags & B_INVAL) { 1017 brelse(bp); 1018 return; 1019 } 1020 if (BUF_REFCNTNB(bp) == 0) 1021 panic("bwrite: buffer is not busy???"); 1022 1023 /* Mark the buffer clean */ 1024 bundirty(bp); 1025 1026 bp->b_flags &= ~(B_ERROR | B_EINTR); 1027 bp->b_flags |= B_CACHE; 1028 bp->b_cmd = BUF_CMD_WRITE; 1029 KKASSERT(bp->b_bio1.bio_done == NULL); 1030 vfs_busy_pages(bp->b_vp, bp); 1031 1032 /* 1033 * Normal bwrites pipeline writes. NOTE: b_bufsize is only 1034 * valid for vnode-backed buffers. 1035 */ 1036 bsetrunningbufspace(bp, bp->b_bufsize); 1037 BUF_KERNPROC(bp); 1038 vn_strategy(bp->b_vp, &bp->b_bio1); 1039 } 1040 1041 /* 1042 * bowrite: 1043 * 1044 * Ordered write. Start output on a buffer, and flag it so that the 1045 * device will write it in the order it was queued. The buffer is 1046 * released when the output completes. bwrite() ( or the VOP routine 1047 * anyway ) is responsible for handling B_INVAL buffers. 1048 */ 1049 int 1050 bowrite(struct buf *bp) 1051 { 1052 bp->b_flags |= B_ORDERED; 1053 bawrite(bp); 1054 return (0); 1055 } 1056 1057 /* 1058 * bdwrite: 1059 * 1060 * Delayed write. (Buffer is marked dirty). Do not bother writing 1061 * anything if the buffer is marked invalid. 1062 * 1063 * Note that since the buffer must be completely valid, we can safely 1064 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 1065 * biodone() in order to prevent getblk from writing the buffer 1066 * out synchronously. 1067 */ 1068 void 1069 bdwrite(struct buf *bp) 1070 { 1071 if (BUF_REFCNTNB(bp) == 0) 1072 panic("bdwrite: buffer is not busy"); 1073 1074 if (bp->b_flags & B_INVAL) { 1075 brelse(bp); 1076 return; 1077 } 1078 bdirty(bp); 1079 1080 if (dsched_is_clear_buf_priv(bp)) 1081 dsched_new_buf(bp); 1082 1083 /* 1084 * Set B_CACHE, indicating that the buffer is fully valid. This is 1085 * true even of NFS now. 1086 */ 1087 bp->b_flags |= B_CACHE; 1088 1089 /* 1090 * This bmap keeps the system from needing to do the bmap later, 1091 * perhaps when the system is attempting to do a sync. Since it 1092 * is likely that the indirect block -- or whatever other datastructure 1093 * that the filesystem needs is still in memory now, it is a good 1094 * thing to do this. Note also, that if the pageout daemon is 1095 * requesting a sync -- there might not be enough memory to do 1096 * the bmap then... So, this is important to do. 1097 */ 1098 if (bp->b_bio2.bio_offset == NOOFFSET) { 1099 VOP_BMAP(bp->b_vp, bp->b_loffset, &bp->b_bio2.bio_offset, 1100 NULL, NULL, BUF_CMD_WRITE); 1101 } 1102 1103 /* 1104 * Because the underlying pages may still be mapped and 1105 * writable trying to set the dirty buffer (b_dirtyoff/end) 1106 * range here will be inaccurate. 1107 * 1108 * However, we must still clean the pages to satisfy the 1109 * vnode_pager and pageout daemon, so theythink the pages 1110 * have been "cleaned". What has really occured is that 1111 * they've been earmarked for later writing by the buffer 1112 * cache. 1113 * 1114 * So we get the b_dirtyoff/end update but will not actually 1115 * depend on it (NFS that is) until the pages are busied for 1116 * writing later on. 1117 */ 1118 vfs_clean_pages(bp); 1119 bqrelse(bp); 1120 1121 /* 1122 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 1123 * due to the softdep code. 1124 */ 1125 } 1126 1127 /* 1128 * Fake write - return pages to VM system as dirty, leave the buffer clean. 1129 * This is used by tmpfs. 1130 * 1131 * It is important for any VFS using this routine to NOT use it for 1132 * IO_SYNC or IO_ASYNC operations which occur when the system really 1133 * wants to flush VM pages to backing store. 1134 */ 1135 void 1136 buwrite(struct buf *bp) 1137 { 1138 vm_page_t m; 1139 int i; 1140 1141 /* 1142 * Only works for VMIO buffers. If the buffer is already 1143 * marked for delayed-write we can't avoid the bdwrite(). 1144 */ 1145 if ((bp->b_flags & B_VMIO) == 0 || (bp->b_flags & B_DELWRI)) { 1146 bdwrite(bp); 1147 return; 1148 } 1149 1150 /* 1151 * Set valid & dirty. 1152 */ 1153 for (i = 0; i < bp->b_xio.xio_npages; i++) { 1154 m = bp->b_xio.xio_pages[i]; 1155 vfs_dirty_one_page(bp, i, m); 1156 } 1157 bqrelse(bp); 1158 } 1159 1160 /* 1161 * bdirty: 1162 * 1163 * Turn buffer into delayed write request by marking it B_DELWRI. 1164 * B_RELBUF and B_NOCACHE must be cleared. 1165 * 1166 * We reassign the buffer to itself to properly update it in the 1167 * dirty/clean lists. 1168 * 1169 * Must be called from a critical section. 1170 * The buffer must be on BQUEUE_NONE. 1171 */ 1172 void 1173 bdirty(struct buf *bp) 1174 { 1175 KASSERT(bp->b_qindex == BQUEUE_NONE, ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1176 if (bp->b_flags & B_NOCACHE) { 1177 kprintf("bdirty: clearing B_NOCACHE on buf %p\n", bp); 1178 bp->b_flags &= ~B_NOCACHE; 1179 } 1180 if (bp->b_flags & B_INVAL) { 1181 kprintf("bdirty: warning, dirtying invalid buffer %p\n", bp); 1182 } 1183 bp->b_flags &= ~B_RELBUF; 1184 1185 if ((bp->b_flags & B_DELWRI) == 0) { 1186 lwkt_gettoken(&bp->b_vp->v_token); 1187 bp->b_flags |= B_DELWRI; 1188 reassignbuf(bp); 1189 lwkt_reltoken(&bp->b_vp->v_token); 1190 1191 spin_lock(&bufcspin); 1192 ++dirtybufcount; 1193 dirtybufspace += bp->b_bufsize; 1194 if (bp->b_flags & B_HEAVY) { 1195 ++dirtybufcounthw; 1196 dirtybufspacehw += bp->b_bufsize; 1197 } 1198 spin_unlock(&bufcspin); 1199 1200 bd_heatup(); 1201 } 1202 } 1203 1204 /* 1205 * Set B_HEAVY, indicating that this is a heavy-weight buffer that 1206 * needs to be flushed with a different buf_daemon thread to avoid 1207 * deadlocks. B_HEAVY also imposes restrictions in getnewbuf(). 1208 */ 1209 void 1210 bheavy(struct buf *bp) 1211 { 1212 if ((bp->b_flags & B_HEAVY) == 0) { 1213 bp->b_flags |= B_HEAVY; 1214 if (bp->b_flags & B_DELWRI) { 1215 spin_lock(&bufcspin); 1216 ++dirtybufcounthw; 1217 dirtybufspacehw += bp->b_bufsize; 1218 spin_unlock(&bufcspin); 1219 } 1220 } 1221 } 1222 1223 /* 1224 * bundirty: 1225 * 1226 * Clear B_DELWRI for buffer. 1227 * 1228 * Must be called from a critical section. 1229 * 1230 * The buffer is typically on BQUEUE_NONE but there is one case in 1231 * brelse() that calls this function after placing the buffer on 1232 * a different queue. 1233 * 1234 * MPSAFE 1235 */ 1236 void 1237 bundirty(struct buf *bp) 1238 { 1239 if (bp->b_flags & B_DELWRI) { 1240 lwkt_gettoken(&bp->b_vp->v_token); 1241 bp->b_flags &= ~B_DELWRI; 1242 reassignbuf(bp); 1243 lwkt_reltoken(&bp->b_vp->v_token); 1244 1245 spin_lock(&bufcspin); 1246 --dirtybufcount; 1247 dirtybufspace -= bp->b_bufsize; 1248 if (bp->b_flags & B_HEAVY) { 1249 --dirtybufcounthw; 1250 dirtybufspacehw -= bp->b_bufsize; 1251 } 1252 spin_unlock(&bufcspin); 1253 1254 bd_signal(bp->b_bufsize); 1255 } 1256 /* 1257 * Since it is now being written, we can clear its deferred write flag. 1258 */ 1259 bp->b_flags &= ~B_DEFERRED; 1260 } 1261 1262 /* 1263 * Set the b_runningbufspace field, used to track how much I/O is 1264 * in progress at any given moment. 1265 */ 1266 void 1267 bsetrunningbufspace(struct buf *bp, int bytes) 1268 { 1269 bp->b_runningbufspace = bytes; 1270 if (bytes) { 1271 spin_lock(&bufcspin); 1272 runningbufspace += bytes; 1273 ++runningbufcount; 1274 spin_unlock(&bufcspin); 1275 } 1276 } 1277 1278 /* 1279 * brelse: 1280 * 1281 * Release a busy buffer and, if requested, free its resources. The 1282 * buffer will be stashed in the appropriate bufqueue[] allowing it 1283 * to be accessed later as a cache entity or reused for other purposes. 1284 * 1285 * MPALMOSTSAFE 1286 */ 1287 void 1288 brelse(struct buf *bp) 1289 { 1290 #ifdef INVARIANTS 1291 int saved_flags = bp->b_flags; 1292 #endif 1293 1294 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1295 1296 /* 1297 * If B_NOCACHE is set we are being asked to destroy the buffer and 1298 * its backing store. Clear B_DELWRI. 1299 * 1300 * B_NOCACHE is set in two cases: (1) when the caller really wants 1301 * to destroy the buffer and backing store and (2) when the caller 1302 * wants to destroy the buffer and backing store after a write 1303 * completes. 1304 */ 1305 if ((bp->b_flags & (B_NOCACHE|B_DELWRI)) == (B_NOCACHE|B_DELWRI)) { 1306 bundirty(bp); 1307 } 1308 1309 if ((bp->b_flags & (B_INVAL | B_DELWRI)) == B_DELWRI) { 1310 /* 1311 * A re-dirtied buffer is only subject to destruction 1312 * by B_INVAL. B_ERROR and B_NOCACHE are ignored. 1313 */ 1314 /* leave buffer intact */ 1315 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR)) || 1316 (bp->b_bufsize <= 0)) { 1317 /* 1318 * Either a failed read or we were asked to free or not 1319 * cache the buffer. This path is reached with B_DELWRI 1320 * set only if B_INVAL is already set. B_NOCACHE governs 1321 * backing store destruction. 1322 * 1323 * NOTE: HAMMER will set B_LOCKED in buf_deallocate if the 1324 * buffer cannot be immediately freed. 1325 */ 1326 bp->b_flags |= B_INVAL; 1327 if (LIST_FIRST(&bp->b_dep) != NULL) 1328 buf_deallocate(bp); 1329 if (bp->b_flags & B_DELWRI) { 1330 spin_lock(&bufcspin); 1331 --dirtybufcount; 1332 dirtybufspace -= bp->b_bufsize; 1333 if (bp->b_flags & B_HEAVY) { 1334 --dirtybufcounthw; 1335 dirtybufspacehw -= bp->b_bufsize; 1336 } 1337 spin_unlock(&bufcspin); 1338 1339 bd_signal(bp->b_bufsize); 1340 } 1341 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1342 } 1343 1344 /* 1345 * We must clear B_RELBUF if B_DELWRI or B_LOCKED is set, 1346 * or if b_refs is non-zero. 1347 * 1348 * If vfs_vmio_release() is called with either bit set, the 1349 * underlying pages may wind up getting freed causing a previous 1350 * write (bdwrite()) to get 'lost' because pages associated with 1351 * a B_DELWRI bp are marked clean. Pages associated with a 1352 * B_LOCKED buffer may be mapped by the filesystem. 1353 * 1354 * If we want to release the buffer ourselves (rather then the 1355 * originator asking us to release it), give the originator a 1356 * chance to countermand the release by setting B_LOCKED. 1357 * 1358 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1359 * if B_DELWRI is set. 1360 * 1361 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1362 * on pages to return pages to the VM page queues. 1363 */ 1364 if ((bp->b_flags & (B_DELWRI | B_LOCKED)) || bp->b_refs) { 1365 bp->b_flags &= ~B_RELBUF; 1366 } else if (vm_page_count_severe()) { 1367 if (LIST_FIRST(&bp->b_dep) != NULL) 1368 buf_deallocate(bp); /* can set B_LOCKED */ 1369 if (bp->b_flags & (B_DELWRI | B_LOCKED)) 1370 bp->b_flags &= ~B_RELBUF; 1371 else 1372 bp->b_flags |= B_RELBUF; 1373 } 1374 1375 /* 1376 * Make sure b_cmd is clear. It may have already been cleared by 1377 * biodone(). 1378 * 1379 * At this point destroying the buffer is governed by the B_INVAL 1380 * or B_RELBUF flags. 1381 */ 1382 bp->b_cmd = BUF_CMD_DONE; 1383 dsched_exit_buf(bp); 1384 1385 /* 1386 * VMIO buffer rundown. Make sure the VM page array is restored 1387 * after an I/O may have replaces some of the pages with bogus pages 1388 * in order to not destroy dirty pages in a fill-in read. 1389 * 1390 * Note that due to the code above, if a buffer is marked B_DELWRI 1391 * then the B_RELBUF and B_NOCACHE bits will always be clear. 1392 * B_INVAL may still be set, however. 1393 * 1394 * For clean buffers, B_INVAL or B_RELBUF will destroy the buffer 1395 * but not the backing store. B_NOCACHE will destroy the backing 1396 * store. 1397 * 1398 * Note that dirty NFS buffers contain byte-granular write ranges 1399 * and should not be destroyed w/ B_INVAL even if the backing store 1400 * is left intact. 1401 */ 1402 if (bp->b_flags & B_VMIO) { 1403 /* 1404 * Rundown for VMIO buffers which are not dirty NFS buffers. 1405 */ 1406 int i, j, resid; 1407 vm_page_t m; 1408 off_t foff; 1409 vm_pindex_t poff; 1410 vm_object_t obj; 1411 struct vnode *vp; 1412 1413 vp = bp->b_vp; 1414 1415 /* 1416 * Get the base offset and length of the buffer. Note that 1417 * in the VMIO case if the buffer block size is not 1418 * page-aligned then b_data pointer may not be page-aligned. 1419 * But our b_xio.xio_pages array *IS* page aligned. 1420 * 1421 * block sizes less then DEV_BSIZE (usually 512) are not 1422 * supported due to the page granularity bits (m->valid, 1423 * m->dirty, etc...). 1424 * 1425 * See man buf(9) for more information 1426 */ 1427 1428 resid = bp->b_bufsize; 1429 foff = bp->b_loffset; 1430 1431 for (i = 0; i < bp->b_xio.xio_npages; i++) { 1432 m = bp->b_xio.xio_pages[i]; 1433 vm_page_flag_clear(m, PG_ZERO); 1434 /* 1435 * If we hit a bogus page, fixup *all* of them 1436 * now. Note that we left these pages wired 1437 * when we removed them so they had better exist, 1438 * and they cannot be ripped out from under us so 1439 * no critical section protection is necessary. 1440 */ 1441 if (m == bogus_page) { 1442 obj = vp->v_object; 1443 poff = OFF_TO_IDX(bp->b_loffset); 1444 1445 vm_object_hold(obj); 1446 for (j = i; j < bp->b_xio.xio_npages; j++) { 1447 vm_page_t mtmp; 1448 1449 mtmp = bp->b_xio.xio_pages[j]; 1450 if (mtmp == bogus_page) { 1451 mtmp = vm_page_lookup(obj, poff + j); 1452 if (!mtmp) { 1453 panic("brelse: page missing"); 1454 } 1455 bp->b_xio.xio_pages[j] = mtmp; 1456 } 1457 } 1458 bp->b_flags &= ~B_HASBOGUS; 1459 vm_object_drop(obj); 1460 1461 if ((bp->b_flags & B_INVAL) == 0) { 1462 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 1463 bp->b_xio.xio_pages, bp->b_xio.xio_npages); 1464 } 1465 m = bp->b_xio.xio_pages[i]; 1466 } 1467 1468 /* 1469 * Invalidate the backing store if B_NOCACHE is set 1470 * (e.g. used with vinvalbuf()). If this is NFS 1471 * we impose a requirement that the block size be 1472 * a multiple of PAGE_SIZE and create a temporary 1473 * hack to basically invalidate the whole page. The 1474 * problem is that NFS uses really odd buffer sizes 1475 * especially when tracking piecemeal writes and 1476 * it also vinvalbuf()'s a lot, which would result 1477 * in only partial page validation and invalidation 1478 * here. If the file page is mmap()'d, however, 1479 * all the valid bits get set so after we invalidate 1480 * here we would end up with weird m->valid values 1481 * like 0xfc. nfs_getpages() can't handle this so 1482 * we clear all the valid bits for the NFS case 1483 * instead of just some of them. 1484 * 1485 * The real bug is the VM system having to set m->valid 1486 * to VM_PAGE_BITS_ALL for faulted-in pages, which 1487 * itself is an artifact of the whole 512-byte 1488 * granular mess that exists to support odd block 1489 * sizes and UFS meta-data block sizes (e.g. 6144). 1490 * A complete rewrite is required. 1491 * 1492 * XXX 1493 */ 1494 if (bp->b_flags & (B_NOCACHE|B_ERROR)) { 1495 int poffset = foff & PAGE_MASK; 1496 int presid; 1497 1498 presid = PAGE_SIZE - poffset; 1499 if (bp->b_vp->v_tag == VT_NFS && 1500 bp->b_vp->v_type == VREG) { 1501 ; /* entire page */ 1502 } else if (presid > resid) { 1503 presid = resid; 1504 } 1505 KASSERT(presid >= 0, ("brelse: extra page")); 1506 vm_page_set_invalid(m, poffset, presid); 1507 1508 /* 1509 * Also make sure any swap cache is removed 1510 * as it is now stale (HAMMER in particular 1511 * uses B_NOCACHE to deal with buffer 1512 * aliasing). 1513 */ 1514 swap_pager_unswapped(m); 1515 } 1516 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1517 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1518 } 1519 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1520 vfs_vmio_release(bp); 1521 } else { 1522 /* 1523 * Rundown for non-VMIO buffers. 1524 */ 1525 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1526 if (bp->b_bufsize) 1527 allocbuf(bp, 0); 1528 KKASSERT (LIST_FIRST(&bp->b_dep) == NULL); 1529 if (bp->b_vp) 1530 brelvp(bp); 1531 } 1532 } 1533 1534 if (bp->b_qindex != BQUEUE_NONE) 1535 panic("brelse: free buffer onto another queue???"); 1536 if (BUF_REFCNTNB(bp) > 1) { 1537 /* Temporary panic to verify exclusive locking */ 1538 /* This panic goes away when we allow shared refs */ 1539 panic("brelse: multiple refs"); 1540 /* NOT REACHED */ 1541 return; 1542 } 1543 1544 /* 1545 * Figure out the correct queue to place the cleaned up buffer on. 1546 * Buffers placed in the EMPTY or EMPTYKVA had better already be 1547 * disassociated from their vnode. 1548 */ 1549 spin_lock(&bufqspin); 1550 if (bp->b_flags & B_LOCKED) { 1551 /* 1552 * Buffers that are locked are placed in the locked queue 1553 * immediately, regardless of their state. 1554 */ 1555 bp->b_qindex = BQUEUE_LOCKED; 1556 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_LOCKED], bp, b_freelist); 1557 } else if (bp->b_bufsize == 0) { 1558 /* 1559 * Buffers with no memory. Due to conditionals near the top 1560 * of brelse() such buffers should probably already be 1561 * marked B_INVAL and disassociated from their vnode. 1562 */ 1563 bp->b_flags |= B_INVAL; 1564 KASSERT(bp->b_vp == NULL, ("bp1 %p flags %08x/%08x vnode %p unexpectededly still associated!", bp, saved_flags, bp->b_flags, bp->b_vp)); 1565 KKASSERT((bp->b_flags & B_HASHED) == 0); 1566 if (bp->b_kvasize) { 1567 bp->b_qindex = BQUEUE_EMPTYKVA; 1568 } else { 1569 bp->b_qindex = BQUEUE_EMPTY; 1570 } 1571 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1572 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) { 1573 /* 1574 * Buffers with junk contents. Again these buffers had better 1575 * already be disassociated from their vnode. 1576 */ 1577 KASSERT(bp->b_vp == NULL, ("bp2 %p flags %08x/%08x vnode %p unexpectededly still associated!", bp, saved_flags, bp->b_flags, bp->b_vp)); 1578 KKASSERT((bp->b_flags & B_HASHED) == 0); 1579 bp->b_flags |= B_INVAL; 1580 bp->b_qindex = BQUEUE_CLEAN; 1581 TAILQ_INSERT_HEAD(&bufqueues[BQUEUE_CLEAN], bp, b_freelist); 1582 } else { 1583 /* 1584 * Remaining buffers. These buffers are still associated with 1585 * their vnode. 1586 */ 1587 switch(bp->b_flags & (B_DELWRI|B_HEAVY)) { 1588 case B_DELWRI: 1589 bp->b_qindex = BQUEUE_DIRTY; 1590 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_DIRTY], bp, b_freelist); 1591 break; 1592 case B_DELWRI | B_HEAVY: 1593 bp->b_qindex = BQUEUE_DIRTY_HW; 1594 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_DIRTY_HW], bp, 1595 b_freelist); 1596 break; 1597 default: 1598 /* 1599 * NOTE: Buffers are always placed at the end of the 1600 * queue. If B_AGE is not set the buffer will cycle 1601 * through the queue twice. 1602 */ 1603 bp->b_qindex = BQUEUE_CLEAN; 1604 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_CLEAN], bp, b_freelist); 1605 break; 1606 } 1607 } 1608 spin_unlock(&bufqspin); 1609 1610 /* 1611 * If B_INVAL, clear B_DELWRI. We've already placed the buffer 1612 * on the correct queue. 1613 */ 1614 if ((bp->b_flags & (B_INVAL|B_DELWRI)) == (B_INVAL|B_DELWRI)) 1615 bundirty(bp); 1616 1617 /* 1618 * The bp is on an appropriate queue unless locked. If it is not 1619 * locked or dirty we can wakeup threads waiting for buffer space. 1620 * 1621 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1622 * if B_INVAL is set ). 1623 */ 1624 if ((bp->b_flags & (B_LOCKED|B_DELWRI)) == 0) 1625 bufcountwakeup(); 1626 1627 /* 1628 * Something we can maybe free or reuse 1629 */ 1630 if (bp->b_bufsize || bp->b_kvasize) 1631 bufspacewakeup(); 1632 1633 /* 1634 * Clean up temporary flags and unlock the buffer. 1635 */ 1636 bp->b_flags &= ~(B_ORDERED | B_NOCACHE | B_RELBUF | B_DIRECT); 1637 BUF_UNLOCK(bp); 1638 } 1639 1640 /* 1641 * bqrelse: 1642 * 1643 * Release a buffer back to the appropriate queue but do not try to free 1644 * it. The buffer is expected to be used again soon. 1645 * 1646 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1647 * biodone() to requeue an async I/O on completion. It is also used when 1648 * known good buffers need to be requeued but we think we may need the data 1649 * again soon. 1650 * 1651 * XXX we should be able to leave the B_RELBUF hint set on completion. 1652 * 1653 * MPSAFE 1654 */ 1655 void 1656 bqrelse(struct buf *bp) 1657 { 1658 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1659 1660 if (bp->b_qindex != BQUEUE_NONE) 1661 panic("bqrelse: free buffer onto another queue???"); 1662 if (BUF_REFCNTNB(bp) > 1) { 1663 /* do not release to free list */ 1664 panic("bqrelse: multiple refs"); 1665 return; 1666 } 1667 1668 buf_act_advance(bp); 1669 1670 spin_lock(&bufqspin); 1671 if (bp->b_flags & B_LOCKED) { 1672 /* 1673 * Locked buffers are released to the locked queue. However, 1674 * if the buffer is dirty it will first go into the dirty 1675 * queue and later on after the I/O completes successfully it 1676 * will be released to the locked queue. 1677 */ 1678 bp->b_qindex = BQUEUE_LOCKED; 1679 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_LOCKED], bp, b_freelist); 1680 } else if (bp->b_flags & B_DELWRI) { 1681 bp->b_qindex = (bp->b_flags & B_HEAVY) ? 1682 BQUEUE_DIRTY_HW : BQUEUE_DIRTY; 1683 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1684 } else if (vm_page_count_severe()) { 1685 /* 1686 * We are too low on memory, we have to try to free the 1687 * buffer (most importantly: the wired pages making up its 1688 * backing store) *now*. 1689 */ 1690 spin_unlock(&bufqspin); 1691 brelse(bp); 1692 return; 1693 } else { 1694 bp->b_qindex = BQUEUE_CLEAN; 1695 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_CLEAN], bp, b_freelist); 1696 } 1697 spin_unlock(&bufqspin); 1698 1699 if ((bp->b_flags & B_LOCKED) == 0 && 1700 ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0)) { 1701 bufcountwakeup(); 1702 } 1703 1704 /* 1705 * Something we can maybe free or reuse. 1706 */ 1707 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1708 bufspacewakeup(); 1709 1710 /* 1711 * Final cleanup and unlock. Clear bits that are only used while a 1712 * buffer is actively locked. 1713 */ 1714 bp->b_flags &= ~(B_ORDERED | B_NOCACHE | B_RELBUF); 1715 dsched_exit_buf(bp); 1716 BUF_UNLOCK(bp); 1717 } 1718 1719 /* 1720 * Hold a buffer, preventing it from being reused. This will prevent 1721 * normal B_RELBUF operations on the buffer but will not prevent B_INVAL 1722 * operations. If a B_INVAL operation occurs the buffer will remain held 1723 * but the underlying pages may get ripped out. 1724 * 1725 * These functions are typically used in VOP_READ/VOP_WRITE functions 1726 * to hold a buffer during a copyin or copyout, preventing deadlocks 1727 * or recursive lock panics when read()/write() is used over mmap()'d 1728 * space. 1729 * 1730 * NOTE: bqhold() requires that the buffer be locked at the time of the 1731 * hold. bqdrop() has no requirements other than the buffer having 1732 * previously been held. 1733 */ 1734 void 1735 bqhold(struct buf *bp) 1736 { 1737 atomic_add_int(&bp->b_refs, 1); 1738 } 1739 1740 void 1741 bqdrop(struct buf *bp) 1742 { 1743 KKASSERT(bp->b_refs > 0); 1744 atomic_add_int(&bp->b_refs, -1); 1745 } 1746 1747 /* 1748 * vfs_vmio_release: 1749 * 1750 * Return backing pages held by the buffer 'bp' back to the VM system 1751 * if possible. The pages are freed if they are no longer valid or 1752 * attempt to free if it was used for direct I/O otherwise they are 1753 * sent to the page cache. 1754 * 1755 * Pages that were marked busy are left alone and skipped. 1756 * 1757 * The KVA mapping (b_data) for the underlying pages is removed by 1758 * this function. 1759 */ 1760 static void 1761 vfs_vmio_release(struct buf *bp) 1762 { 1763 int i; 1764 vm_page_t m; 1765 1766 for (i = 0; i < bp->b_xio.xio_npages; i++) { 1767 m = bp->b_xio.xio_pages[i]; 1768 bp->b_xio.xio_pages[i] = NULL; 1769 1770 vm_page_busy_wait(m, FALSE, "vmiopg"); 1771 1772 /* 1773 * The VFS is telling us this is not a meta-data buffer 1774 * even if it is backed by a block device. 1775 */ 1776 if (bp->b_flags & B_NOTMETA) 1777 vm_page_flag_set(m, PG_NOTMETA); 1778 1779 /* 1780 * This is a very important bit of code. We try to track 1781 * VM page use whether the pages are wired into the buffer 1782 * cache or not. While wired into the buffer cache the 1783 * bp tracks the act_count. 1784 * 1785 * We can choose to place unwired pages on the inactive 1786 * queue (0) or active queue (1). If we place too many 1787 * on the active queue the queue will cycle the act_count 1788 * on pages we'd like to keep, just from single-use pages 1789 * (such as when doing a tar-up or file scan). 1790 */ 1791 if (bp->b_act_count < vm_cycle_point) 1792 vm_page_unwire(m, 0); 1793 else 1794 vm_page_unwire(m, 1); 1795 1796 /* 1797 * We don't mess with busy pages, it is the responsibility 1798 * of the process that busied the pages to deal with them. 1799 * 1800 * However, the caller may have marked the page invalid and 1801 * we must still make sure the page is no longer mapped. 1802 */ 1803 if ((m->flags & PG_BUSY) || (m->busy != 0)) { 1804 vm_page_protect(m, VM_PROT_NONE); 1805 vm_page_wakeup(m); 1806 continue; 1807 } 1808 1809 if (m->wire_count == 0) { 1810 vm_page_flag_clear(m, PG_ZERO); 1811 /* 1812 * Might as well free the page if we can and it has 1813 * no valid data. We also free the page if the 1814 * buffer was used for direct I/O. 1815 */ 1816 #if 0 1817 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && 1818 m->hold_count == 0) { 1819 vm_page_protect(m, VM_PROT_NONE); 1820 vm_page_free(m); 1821 } else 1822 #endif 1823 /* 1824 * Cache the page if we are really low on free 1825 * pages. 1826 * 1827 * Also bypass the active and inactive queues 1828 * if B_NOTMETA is set. This flag is set by HAMMER 1829 * on a regular file buffer when double buffering 1830 * is enabled or on a block device buffer representing 1831 * file data when double buffering is not enabled. 1832 * The flag prevents two copies of the same data from 1833 * being cached for long periods of time. 1834 */ 1835 if (bp->b_flags & B_DIRECT) { 1836 vm_page_wakeup(m); 1837 vm_page_try_to_free(m); 1838 } else if ((bp->b_flags & B_NOTMETA) || 1839 vm_page_count_severe()) { 1840 m->act_count = bp->b_act_count; 1841 vm_page_wakeup(m); 1842 vm_page_try_to_cache(m); 1843 } else { 1844 m->act_count = bp->b_act_count; 1845 vm_page_wakeup(m); 1846 } 1847 } else { 1848 vm_page_wakeup(m); 1849 } 1850 } 1851 1852 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), 1853 bp->b_xio.xio_npages); 1854 if (bp->b_bufsize) { 1855 bufspacewakeup(); 1856 bp->b_bufsize = 0; 1857 } 1858 bp->b_xio.xio_npages = 0; 1859 bp->b_flags &= ~B_VMIO; 1860 KKASSERT (LIST_FIRST(&bp->b_dep) == NULL); 1861 if (bp->b_vp) 1862 brelvp(bp); 1863 } 1864 1865 /* 1866 * vfs_bio_awrite: 1867 * 1868 * Implement clustered async writes for clearing out B_DELWRI buffers. 1869 * This is much better then the old way of writing only one buffer at 1870 * a time. Note that we may not be presented with the buffers in the 1871 * correct order, so we search for the cluster in both directions. 1872 * 1873 * The buffer is locked on call. 1874 */ 1875 int 1876 vfs_bio_awrite(struct buf *bp) 1877 { 1878 int i; 1879 int j; 1880 off_t loffset = bp->b_loffset; 1881 struct vnode *vp = bp->b_vp; 1882 int nbytes; 1883 struct buf *bpa; 1884 int nwritten; 1885 int size; 1886 1887 /* 1888 * right now we support clustered writing only to regular files. If 1889 * we find a clusterable block we could be in the middle of a cluster 1890 * rather then at the beginning. 1891 * 1892 * NOTE: b_bio1 contains the logical loffset and is aliased 1893 * to b_loffset. b_bio2 contains the translated block number. 1894 */ 1895 if ((vp->v_type == VREG) && 1896 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1897 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1898 1899 size = vp->v_mount->mnt_stat.f_iosize; 1900 1901 for (i = size; i < MAXPHYS; i += size) { 1902 if ((bpa = findblk(vp, loffset + i, FINDBLK_TEST)) && 1903 BUF_REFCNT(bpa) == 0 && 1904 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == 1905 (B_DELWRI | B_CLUSTEROK)) && 1906 (bpa->b_bufsize == size)) { 1907 if ((bpa->b_bio2.bio_offset == NOOFFSET) || 1908 (bpa->b_bio2.bio_offset != 1909 bp->b_bio2.bio_offset + i)) 1910 break; 1911 } else { 1912 break; 1913 } 1914 } 1915 for (j = size; i + j <= MAXPHYS && j <= loffset; j += size) { 1916 if ((bpa = findblk(vp, loffset - j, FINDBLK_TEST)) && 1917 BUF_REFCNT(bpa) == 0 && 1918 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == 1919 (B_DELWRI | B_CLUSTEROK)) && 1920 (bpa->b_bufsize == size)) { 1921 if ((bpa->b_bio2.bio_offset == NOOFFSET) || 1922 (bpa->b_bio2.bio_offset != 1923 bp->b_bio2.bio_offset - j)) 1924 break; 1925 } else { 1926 break; 1927 } 1928 } 1929 j -= size; 1930 nbytes = (i + j); 1931 1932 /* 1933 * this is a possible cluster write 1934 */ 1935 if (nbytes != size) { 1936 BUF_UNLOCK(bp); 1937 nwritten = cluster_wbuild(vp, size, 1938 loffset - j, nbytes); 1939 return nwritten; 1940 } 1941 } 1942 1943 /* 1944 * default (old) behavior, writing out only one block 1945 * 1946 * XXX returns b_bufsize instead of b_bcount for nwritten? 1947 */ 1948 nwritten = bp->b_bufsize; 1949 bremfree(bp); 1950 bawrite(bp); 1951 1952 return nwritten; 1953 } 1954 1955 /* 1956 * getnewbuf: 1957 * 1958 * Find and initialize a new buffer header, freeing up existing buffers 1959 * in the bufqueues as necessary. The new buffer is returned locked. 1960 * 1961 * Important: B_INVAL is not set. If the caller wishes to throw the 1962 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1963 * 1964 * We block if: 1965 * We have insufficient buffer headers 1966 * We have insufficient buffer space 1967 * buffer_map is too fragmented ( space reservation fails ) 1968 * If we have to flush dirty buffers ( but we try to avoid this ) 1969 * 1970 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1971 * Instead we ask the buf daemon to do it for us. We attempt to 1972 * avoid piecemeal wakeups of the pageout daemon. 1973 * 1974 * MPALMOSTSAFE 1975 */ 1976 struct buf * 1977 getnewbuf(int blkflags, int slptimeo, int size, int maxsize) 1978 { 1979 struct buf *bp; 1980 struct buf *nbp; 1981 int defrag = 0; 1982 int nqindex; 1983 int slpflags = (blkflags & GETBLK_PCATCH) ? PCATCH : 0; 1984 static int flushingbufs; 1985 1986 /* 1987 * We can't afford to block since we might be holding a vnode lock, 1988 * which may prevent system daemons from running. We deal with 1989 * low-memory situations by proactively returning memory and running 1990 * async I/O rather then sync I/O. 1991 */ 1992 1993 ++getnewbufcalls; 1994 --getnewbufrestarts; 1995 restart: 1996 ++getnewbufrestarts; 1997 1998 /* 1999 * Setup for scan. If we do not have enough free buffers, 2000 * we setup a degenerate case that immediately fails. Note 2001 * that if we are specially marked process, we are allowed to 2002 * dip into our reserves. 2003 * 2004 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 2005 * 2006 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 2007 * However, there are a number of cases (defragging, reusing, ...) 2008 * where we cannot backup. 2009 */ 2010 nqindex = BQUEUE_EMPTYKVA; 2011 spin_lock(&bufqspin); 2012 nbp = TAILQ_FIRST(&bufqueues[BQUEUE_EMPTYKVA]); 2013 2014 if (nbp == NULL) { 2015 /* 2016 * If no EMPTYKVA buffers and we are either 2017 * defragging or reusing, locate a CLEAN buffer 2018 * to free or reuse. If bufspace useage is low 2019 * skip this step so we can allocate a new buffer. 2020 */ 2021 if (defrag || bufspace >= lobufspace) { 2022 nqindex = BQUEUE_CLEAN; 2023 nbp = TAILQ_FIRST(&bufqueues[BQUEUE_CLEAN]); 2024 } 2025 2026 /* 2027 * If we could not find or were not allowed to reuse a 2028 * CLEAN buffer, check to see if it is ok to use an EMPTY 2029 * buffer. We can only use an EMPTY buffer if allocating 2030 * its KVA would not otherwise run us out of buffer space. 2031 */ 2032 if (nbp == NULL && defrag == 0 && 2033 bufspace + maxsize < hibufspace) { 2034 nqindex = BQUEUE_EMPTY; 2035 nbp = TAILQ_FIRST(&bufqueues[BQUEUE_EMPTY]); 2036 } 2037 } 2038 2039 /* 2040 * Run scan, possibly freeing data and/or kva mappings on the fly 2041 * depending. 2042 * 2043 * WARNING! bufqspin is held! 2044 */ 2045 while ((bp = nbp) != NULL) { 2046 int qindex = nqindex; 2047 2048 nbp = TAILQ_NEXT(bp, b_freelist); 2049 2050 /* 2051 * BQUEUE_CLEAN - B_AGE special case. If not set the bp 2052 * cycles through the queue twice before being selected. 2053 */ 2054 if (qindex == BQUEUE_CLEAN && 2055 (bp->b_flags & B_AGE) == 0 && nbp) { 2056 bp->b_flags |= B_AGE; 2057 TAILQ_REMOVE(&bufqueues[qindex], bp, b_freelist); 2058 TAILQ_INSERT_TAIL(&bufqueues[qindex], bp, b_freelist); 2059 continue; 2060 } 2061 2062 /* 2063 * Calculate next bp ( we can only use it if we do not block 2064 * or do other fancy things ). 2065 */ 2066 if (nbp == NULL) { 2067 switch(qindex) { 2068 case BQUEUE_EMPTY: 2069 nqindex = BQUEUE_EMPTYKVA; 2070 if ((nbp = TAILQ_FIRST(&bufqueues[BQUEUE_EMPTYKVA]))) 2071 break; 2072 /* fall through */ 2073 case BQUEUE_EMPTYKVA: 2074 nqindex = BQUEUE_CLEAN; 2075 if ((nbp = TAILQ_FIRST(&bufqueues[BQUEUE_CLEAN]))) 2076 break; 2077 /* fall through */ 2078 case BQUEUE_CLEAN: 2079 /* 2080 * nbp is NULL. 2081 */ 2082 break; 2083 } 2084 } 2085 2086 /* 2087 * Sanity Checks 2088 */ 2089 KASSERT(bp->b_qindex == qindex, 2090 ("getnewbuf: inconsistent queue %d bp %p", qindex, bp)); 2091 2092 /* 2093 * Note: we no longer distinguish between VMIO and non-VMIO 2094 * buffers. 2095 */ 2096 KASSERT((bp->b_flags & B_DELWRI) == 0, 2097 ("delwri buffer %p found in queue %d", bp, qindex)); 2098 2099 /* 2100 * Do not try to reuse a buffer with a non-zero b_refs. 2101 * This is an unsynchronized test. A synchronized test 2102 * is also performed after we lock the buffer. 2103 */ 2104 if (bp->b_refs) 2105 continue; 2106 2107 /* 2108 * If we are defragging then we need a buffer with 2109 * b_kvasize != 0. XXX this situation should no longer 2110 * occur, if defrag is non-zero the buffer's b_kvasize 2111 * should also be non-zero at this point. XXX 2112 */ 2113 if (defrag && bp->b_kvasize == 0) { 2114 kprintf("Warning: defrag empty buffer %p\n", bp); 2115 continue; 2116 } 2117 2118 /* 2119 * Start freeing the bp. This is somewhat involved. nbp 2120 * remains valid only for BQUEUE_EMPTY[KVA] bp's. Buffers 2121 * on the clean list must be disassociated from their 2122 * current vnode. Buffers on the empty[kva] lists have 2123 * already been disassociated. 2124 * 2125 * b_refs is checked after locking along with queue changes. 2126 * We must check here to deal with zero->nonzero transitions 2127 * made by the owner of the buffer lock, which is used by 2128 * VFS's to hold the buffer while issuing an unlocked 2129 * uiomove()s. We cannot invalidate the buffer's pages 2130 * for this case. Once we successfully lock a buffer the 2131 * only 0->1 transitions of b_refs will occur via findblk(). 2132 * 2133 * We must also check for queue changes after successful 2134 * locking as the current lock holder may dispose of the 2135 * buffer and change its queue. 2136 */ 2137 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) { 2138 spin_unlock(&bufqspin); 2139 tsleep(&bd_request, 0, "gnbxxx", (hz + 99) / 100); 2140 goto restart; 2141 } 2142 if (bp->b_qindex != qindex || bp->b_refs) { 2143 spin_unlock(&bufqspin); 2144 BUF_UNLOCK(bp); 2145 goto restart; 2146 } 2147 bremfree_locked(bp); 2148 spin_unlock(&bufqspin); 2149 2150 /* 2151 * Dependancies must be handled before we disassociate the 2152 * vnode. 2153 * 2154 * NOTE: HAMMER will set B_LOCKED if the buffer cannot 2155 * be immediately disassociated. HAMMER then becomes 2156 * responsible for releasing the buffer. 2157 * 2158 * NOTE: bufqspin is UNLOCKED now. 2159 */ 2160 if (LIST_FIRST(&bp->b_dep) != NULL) { 2161 buf_deallocate(bp); 2162 if (bp->b_flags & B_LOCKED) { 2163 bqrelse(bp); 2164 goto restart; 2165 } 2166 KKASSERT(LIST_FIRST(&bp->b_dep) == NULL); 2167 } 2168 2169 if (qindex == BQUEUE_CLEAN) { 2170 if (bp->b_flags & B_VMIO) 2171 vfs_vmio_release(bp); 2172 if (bp->b_vp) 2173 brelvp(bp); 2174 } 2175 2176 /* 2177 * NOTE: nbp is now entirely invalid. We can only restart 2178 * the scan from this point on. 2179 * 2180 * Get the rest of the buffer freed up. b_kva* is still 2181 * valid after this operation. 2182 */ 2183 KASSERT(bp->b_vp == NULL, 2184 ("bp3 %p flags %08x vnode %p qindex %d " 2185 "unexpectededly still associated!", 2186 bp, bp->b_flags, bp->b_vp, qindex)); 2187 KKASSERT((bp->b_flags & B_HASHED) == 0); 2188 2189 /* 2190 * critical section protection is not required when 2191 * scrapping a buffer's contents because it is already 2192 * wired. 2193 */ 2194 if (bp->b_bufsize) 2195 allocbuf(bp, 0); 2196 2197 bp->b_flags = B_BNOCLIP; 2198 bp->b_cmd = BUF_CMD_DONE; 2199 bp->b_vp = NULL; 2200 bp->b_error = 0; 2201 bp->b_resid = 0; 2202 bp->b_bcount = 0; 2203 bp->b_xio.xio_npages = 0; 2204 bp->b_dirtyoff = bp->b_dirtyend = 0; 2205 bp->b_act_count = ACT_INIT; 2206 reinitbufbio(bp); 2207 KKASSERT(LIST_FIRST(&bp->b_dep) == NULL); 2208 buf_dep_init(bp); 2209 if (blkflags & GETBLK_BHEAVY) 2210 bp->b_flags |= B_HEAVY; 2211 2212 /* 2213 * If we are defragging then free the buffer. 2214 */ 2215 if (defrag) { 2216 bp->b_flags |= B_INVAL; 2217 bfreekva(bp); 2218 brelse(bp); 2219 defrag = 0; 2220 goto restart; 2221 } 2222 2223 /* 2224 * If we are overcomitted then recover the buffer and its 2225 * KVM space. This occurs in rare situations when multiple 2226 * processes are blocked in getnewbuf() or allocbuf(). 2227 */ 2228 if (bufspace >= hibufspace) 2229 flushingbufs = 1; 2230 if (flushingbufs && bp->b_kvasize != 0) { 2231 bp->b_flags |= B_INVAL; 2232 bfreekva(bp); 2233 brelse(bp); 2234 goto restart; 2235 } 2236 if (bufspace < lobufspace) 2237 flushingbufs = 0; 2238 2239 /* 2240 * b_refs can transition to a non-zero value while we hold 2241 * the buffer locked due to a findblk(). Our brelvp() above 2242 * interlocked any future possible transitions due to 2243 * findblk()s. 2244 * 2245 * If we find b_refs to be non-zero we can destroy the 2246 * buffer's contents but we cannot yet reuse the buffer. 2247 */ 2248 if (bp->b_refs) { 2249 bp->b_flags |= B_INVAL; 2250 bfreekva(bp); 2251 brelse(bp); 2252 goto restart; 2253 } 2254 break; 2255 /* NOT REACHED, bufqspin not held */ 2256 } 2257 2258 /* 2259 * If we exhausted our list, sleep as appropriate. We may have to 2260 * wakeup various daemons and write out some dirty buffers. 2261 * 2262 * Generally we are sleeping due to insufficient buffer space. 2263 * 2264 * NOTE: bufqspin is held if bp is NULL, else it is not held. 2265 */ 2266 if (bp == NULL) { 2267 int flags; 2268 char *waitmsg; 2269 2270 spin_unlock(&bufqspin); 2271 if (defrag) { 2272 flags = VFS_BIO_NEED_BUFSPACE; 2273 waitmsg = "nbufkv"; 2274 } else if (bufspace >= hibufspace) { 2275 waitmsg = "nbufbs"; 2276 flags = VFS_BIO_NEED_BUFSPACE; 2277 } else { 2278 waitmsg = "newbuf"; 2279 flags = VFS_BIO_NEED_ANY; 2280 } 2281 2282 bd_speedup(); /* heeeelp */ 2283 spin_lock(&bufcspin); 2284 needsbuffer |= flags; 2285 while (needsbuffer & flags) { 2286 if (ssleep(&needsbuffer, &bufcspin, 2287 slpflags, waitmsg, slptimeo)) { 2288 spin_unlock(&bufcspin); 2289 return (NULL); 2290 } 2291 } 2292 spin_unlock(&bufcspin); 2293 } else { 2294 /* 2295 * We finally have a valid bp. We aren't quite out of the 2296 * woods, we still have to reserve kva space. In order 2297 * to keep fragmentation sane we only allocate kva in 2298 * BKVASIZE chunks. 2299 * 2300 * (bufqspin is not held) 2301 */ 2302 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2303 2304 if (maxsize != bp->b_kvasize) { 2305 vm_offset_t addr = 0; 2306 int count; 2307 2308 bfreekva(bp); 2309 2310 count = vm_map_entry_reserve(MAP_RESERVE_COUNT); 2311 vm_map_lock(&buffer_map); 2312 2313 if (vm_map_findspace(&buffer_map, 2314 vm_map_min(&buffer_map), maxsize, 2315 maxsize, 0, &addr)) { 2316 /* 2317 * Uh oh. Buffer map is too fragmented. We 2318 * must defragment the map. 2319 */ 2320 vm_map_unlock(&buffer_map); 2321 vm_map_entry_release(count); 2322 ++bufdefragcnt; 2323 defrag = 1; 2324 bp->b_flags |= B_INVAL; 2325 brelse(bp); 2326 goto restart; 2327 } 2328 if (addr) { 2329 vm_map_insert(&buffer_map, &count, 2330 NULL, 0, 2331 addr, addr + maxsize, 2332 VM_MAPTYPE_NORMAL, 2333 VM_PROT_ALL, VM_PROT_ALL, 2334 MAP_NOFAULT); 2335 2336 bp->b_kvabase = (caddr_t) addr; 2337 bp->b_kvasize = maxsize; 2338 bufspace += bp->b_kvasize; 2339 ++bufreusecnt; 2340 } 2341 vm_map_unlock(&buffer_map); 2342 vm_map_entry_release(count); 2343 } 2344 bp->b_data = bp->b_kvabase; 2345 } 2346 return(bp); 2347 } 2348 2349 /* 2350 * This routine is called in an emergency to recover VM pages from the 2351 * buffer cache by cashing in clean buffers. The idea is to recover 2352 * enough pages to be able to satisfy a stuck bio_page_alloc(). 2353 * 2354 * MPSAFE 2355 */ 2356 static int 2357 recoverbufpages(void) 2358 { 2359 struct buf *bp; 2360 int bytes = 0; 2361 2362 ++recoverbufcalls; 2363 2364 spin_lock(&bufqspin); 2365 while (bytes < MAXBSIZE) { 2366 bp = TAILQ_FIRST(&bufqueues[BQUEUE_CLEAN]); 2367 if (bp == NULL) 2368 break; 2369 2370 /* 2371 * BQUEUE_CLEAN - B_AGE special case. If not set the bp 2372 * cycles through the queue twice before being selected. 2373 */ 2374 if ((bp->b_flags & B_AGE) == 0 && TAILQ_NEXT(bp, b_freelist)) { 2375 bp->b_flags |= B_AGE; 2376 TAILQ_REMOVE(&bufqueues[BQUEUE_CLEAN], bp, b_freelist); 2377 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_CLEAN], 2378 bp, b_freelist); 2379 continue; 2380 } 2381 2382 /* 2383 * Sanity Checks 2384 */ 2385 KKASSERT(bp->b_qindex == BQUEUE_CLEAN); 2386 KKASSERT((bp->b_flags & B_DELWRI) == 0); 2387 2388 /* 2389 * Start freeing the bp. This is somewhat involved. 2390 * 2391 * Buffers on the clean list must be disassociated from 2392 * their current vnode 2393 */ 2394 2395 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) { 2396 kprintf("recoverbufpages: warning, locked buf %p, " 2397 "race corrected\n", 2398 bp); 2399 ssleep(&bd_request, &bufqspin, 0, "gnbxxx", hz / 100); 2400 continue; 2401 } 2402 if (bp->b_qindex != BQUEUE_CLEAN) { 2403 kprintf("recoverbufpages: warning, BUF_LOCK blocked " 2404 "unexpectedly on buf %p index %d, race " 2405 "corrected\n", 2406 bp, bp->b_qindex); 2407 BUF_UNLOCK(bp); 2408 continue; 2409 } 2410 bremfree_locked(bp); 2411 spin_unlock(&bufqspin); 2412 2413 /* 2414 * Dependancies must be handled before we disassociate the 2415 * vnode. 2416 * 2417 * NOTE: HAMMER will set B_LOCKED if the buffer cannot 2418 * be immediately disassociated. HAMMER then becomes 2419 * responsible for releasing the buffer. 2420 */ 2421 if (LIST_FIRST(&bp->b_dep) != NULL) { 2422 buf_deallocate(bp); 2423 if (bp->b_flags & B_LOCKED) { 2424 bqrelse(bp); 2425 spin_lock(&bufqspin); 2426 continue; 2427 } 2428 KKASSERT(LIST_FIRST(&bp->b_dep) == NULL); 2429 } 2430 2431 bytes += bp->b_bufsize; 2432 2433 if (bp->b_flags & B_VMIO) { 2434 bp->b_flags |= B_DIRECT; /* try to free pages */ 2435 vfs_vmio_release(bp); 2436 } 2437 if (bp->b_vp) 2438 brelvp(bp); 2439 2440 KKASSERT(bp->b_vp == NULL); 2441 KKASSERT((bp->b_flags & B_HASHED) == 0); 2442 2443 /* 2444 * critical section protection is not required when 2445 * scrapping a buffer's contents because it is already 2446 * wired. 2447 */ 2448 if (bp->b_bufsize) 2449 allocbuf(bp, 0); 2450 2451 bp->b_flags = B_BNOCLIP; 2452 bp->b_cmd = BUF_CMD_DONE; 2453 bp->b_vp = NULL; 2454 bp->b_error = 0; 2455 bp->b_resid = 0; 2456 bp->b_bcount = 0; 2457 bp->b_xio.xio_npages = 0; 2458 bp->b_dirtyoff = bp->b_dirtyend = 0; 2459 reinitbufbio(bp); 2460 KKASSERT(LIST_FIRST(&bp->b_dep) == NULL); 2461 buf_dep_init(bp); 2462 bp->b_flags |= B_INVAL; 2463 /* bfreekva(bp); */ 2464 brelse(bp); 2465 spin_lock(&bufqspin); 2466 } 2467 spin_unlock(&bufqspin); 2468 return(bytes); 2469 } 2470 2471 /* 2472 * buf_daemon: 2473 * 2474 * Buffer flushing daemon. Buffers are normally flushed by the 2475 * update daemon but if it cannot keep up this process starts to 2476 * take the load in an attempt to prevent getnewbuf() from blocking. 2477 * 2478 * Once a flush is initiated it does not stop until the number 2479 * of buffers falls below lodirtybuffers, but we will wake up anyone 2480 * waiting at the mid-point. 2481 */ 2482 2483 static struct kproc_desc buf_kp = { 2484 "bufdaemon", 2485 buf_daemon, 2486 &bufdaemon_td 2487 }; 2488 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, 2489 kproc_start, &buf_kp) 2490 2491 static struct kproc_desc bufhw_kp = { 2492 "bufdaemon_hw", 2493 buf_daemon_hw, 2494 &bufdaemonhw_td 2495 }; 2496 SYSINIT(bufdaemon_hw, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, 2497 kproc_start, &bufhw_kp) 2498 2499 /* 2500 * MPSAFE thread 2501 */ 2502 static void 2503 buf_daemon1(struct thread *td, int queue, int (*buf_limit_fn)(long), 2504 int *bd_req) 2505 { 2506 long limit; 2507 2508 /* 2509 * This process needs to be suspended prior to shutdown sync. 2510 */ 2511 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc, 2512 td, SHUTDOWN_PRI_LAST); 2513 curthread->td_flags |= TDF_SYSTHREAD; 2514 2515 /* 2516 * This process is allowed to take the buffer cache to the limit 2517 */ 2518 for (;;) { 2519 kproc_suspend_loop(); 2520 2521 /* 2522 * Do the flush as long as the number of dirty buffers 2523 * (including those running) exceeds lodirtybufspace. 2524 * 2525 * When flushing limit running I/O to hirunningspace 2526 * Do the flush. Limit the amount of in-transit I/O we 2527 * allow to build up, otherwise we would completely saturate 2528 * the I/O system. Wakeup any waiting processes before we 2529 * normally would so they can run in parallel with our drain. 2530 * 2531 * Our aggregate normal+HW lo water mark is lodirtybufspace, 2532 * but because we split the operation into two threads we 2533 * have to cut it in half for each thread. 2534 */ 2535 waitrunningbufspace(); 2536 limit = lodirtybufspace / 2; 2537 while (buf_limit_fn(limit)) { 2538 if (flushbufqueues(queue) == 0) 2539 break; 2540 if (runningbufspace < hirunningspace) 2541 continue; 2542 waitrunningbufspace(); 2543 } 2544 2545 /* 2546 * We reached our low water mark, reset the 2547 * request and sleep until we are needed again. 2548 * The sleep is just so the suspend code works. 2549 */ 2550 spin_lock(&bufcspin); 2551 if (*bd_req == 0) 2552 ssleep(bd_req, &bufcspin, 0, "psleep", hz); 2553 *bd_req = 0; 2554 spin_unlock(&bufcspin); 2555 } 2556 } 2557 2558 static int 2559 buf_daemon_limit(long limit) 2560 { 2561 return (runningbufspace + dirtybufspace > limit || 2562 dirtybufcount - dirtybufcounthw >= nbuf / 2); 2563 } 2564 2565 static int 2566 buf_daemon_hw_limit(long limit) 2567 { 2568 return (runningbufspace + dirtybufspacehw > limit || 2569 dirtybufcounthw >= nbuf / 2); 2570 } 2571 2572 static void 2573 buf_daemon(void) 2574 { 2575 buf_daemon1(bufdaemon_td, BQUEUE_DIRTY, buf_daemon_limit, 2576 &bd_request); 2577 } 2578 2579 static void 2580 buf_daemon_hw(void) 2581 { 2582 buf_daemon1(bufdaemonhw_td, BQUEUE_DIRTY_HW, buf_daemon_hw_limit, 2583 &bd_request_hw); 2584 } 2585 2586 /* 2587 * flushbufqueues: 2588 * 2589 * Try to flush a buffer in the dirty queue. We must be careful to 2590 * free up B_INVAL buffers instead of write them, which NFS is 2591 * particularly sensitive to. 2592 * 2593 * B_RELBUF may only be set by VFSs. We do set B_AGE to indicate 2594 * that we really want to try to get the buffer out and reuse it 2595 * due to the write load on the machine. 2596 * 2597 * We must lock the buffer in order to check its validity before we 2598 * can mess with its contents. bufqspin isn't enough. 2599 */ 2600 static int 2601 flushbufqueues(bufq_type_t q) 2602 { 2603 struct buf *bp; 2604 int r = 0; 2605 int spun; 2606 2607 spin_lock(&bufqspin); 2608 spun = 1; 2609 2610 bp = TAILQ_FIRST(&bufqueues[q]); 2611 while (bp) { 2612 if ((bp->b_flags & B_DELWRI) == 0) { 2613 kprintf("Unexpected clean buffer %p\n", bp); 2614 bp = TAILQ_NEXT(bp, b_freelist); 2615 continue; 2616 } 2617 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) { 2618 bp = TAILQ_NEXT(bp, b_freelist); 2619 continue; 2620 } 2621 KKASSERT(bp->b_qindex == q); 2622 2623 /* 2624 * Must recheck B_DELWRI after successfully locking 2625 * the buffer. 2626 */ 2627 if ((bp->b_flags & B_DELWRI) == 0) { 2628 BUF_UNLOCK(bp); 2629 bp = TAILQ_NEXT(bp, b_freelist); 2630 continue; 2631 } 2632 2633 if (bp->b_flags & B_INVAL) { 2634 _bremfree(bp); 2635 spin_unlock(&bufqspin); 2636 spun = 0; 2637 brelse(bp); 2638 ++r; 2639 break; 2640 } 2641 2642 spin_unlock(&bufqspin); 2643 lwkt_yield(); 2644 spun = 0; 2645 2646 if (LIST_FIRST(&bp->b_dep) != NULL && 2647 (bp->b_flags & B_DEFERRED) == 0 && 2648 buf_countdeps(bp, 0)) { 2649 spin_lock(&bufqspin); 2650 spun = 1; 2651 TAILQ_REMOVE(&bufqueues[q], bp, b_freelist); 2652 TAILQ_INSERT_TAIL(&bufqueues[q], bp, b_freelist); 2653 bp->b_flags |= B_DEFERRED; 2654 BUF_UNLOCK(bp); 2655 bp = TAILQ_FIRST(&bufqueues[q]); 2656 continue; 2657 } 2658 2659 /* 2660 * If the buffer has a dependancy, buf_checkwrite() must 2661 * also return 0 for us to be able to initate the write. 2662 * 2663 * If the buffer is flagged B_ERROR it may be requeued 2664 * over and over again, we try to avoid a live lock. 2665 * 2666 * NOTE: buf_checkwrite is MPSAFE. 2667 */ 2668 if (LIST_FIRST(&bp->b_dep) != NULL && buf_checkwrite(bp)) { 2669 bremfree(bp); 2670 brelse(bp); 2671 } else if (bp->b_flags & B_ERROR) { 2672 tsleep(bp, 0, "bioer", 1); 2673 bp->b_flags &= ~B_AGE; 2674 vfs_bio_awrite(bp); 2675 } else { 2676 bp->b_flags |= B_AGE; 2677 vfs_bio_awrite(bp); 2678 } 2679 ++r; 2680 break; 2681 } 2682 if (spun) 2683 spin_unlock(&bufqspin); 2684 return (r); 2685 } 2686 2687 /* 2688 * inmem: 2689 * 2690 * Returns true if no I/O is needed to access the associated VM object. 2691 * This is like findblk except it also hunts around in the VM system for 2692 * the data. 2693 * 2694 * Note that we ignore vm_page_free() races from interrupts against our 2695 * lookup, since if the caller is not protected our return value will not 2696 * be any more valid then otherwise once we exit the critical section. 2697 */ 2698 int 2699 inmem(struct vnode *vp, off_t loffset) 2700 { 2701 vm_object_t obj; 2702 vm_offset_t toff, tinc, size; 2703 vm_page_t m; 2704 int res = 1; 2705 2706 if (findblk(vp, loffset, FINDBLK_TEST)) 2707 return 1; 2708 if (vp->v_mount == NULL) 2709 return 0; 2710 if ((obj = vp->v_object) == NULL) 2711 return 0; 2712 2713 size = PAGE_SIZE; 2714 if (size > vp->v_mount->mnt_stat.f_iosize) 2715 size = vp->v_mount->mnt_stat.f_iosize; 2716 2717 vm_object_hold(obj); 2718 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2719 m = vm_page_lookup(obj, OFF_TO_IDX(loffset + toff)); 2720 if (m == NULL) { 2721 res = 0; 2722 break; 2723 } 2724 tinc = size; 2725 if (tinc > PAGE_SIZE - ((toff + loffset) & PAGE_MASK)) 2726 tinc = PAGE_SIZE - ((toff + loffset) & PAGE_MASK); 2727 if (vm_page_is_valid(m, 2728 (vm_offset_t) ((toff + loffset) & PAGE_MASK), tinc) == 0) { 2729 res = 0; 2730 break; 2731 } 2732 } 2733 vm_object_drop(obj); 2734 return (res); 2735 } 2736 2737 /* 2738 * findblk: 2739 * 2740 * Locate and return the specified buffer. Unless flagged otherwise, 2741 * a locked buffer will be returned if it exists or NULL if it does not. 2742 * 2743 * findblk()'d buffers are still on the bufqueues and if you intend 2744 * to use your (locked NON-TEST) buffer you need to bremfree(bp) 2745 * and possibly do other stuff to it. 2746 * 2747 * FINDBLK_TEST - Do not lock the buffer. The caller is responsible 2748 * for locking the buffer and ensuring that it remains 2749 * the desired buffer after locking. 2750 * 2751 * FINDBLK_NBLOCK - Lock the buffer non-blocking. If we are unable 2752 * to acquire the lock we return NULL, even if the 2753 * buffer exists. 2754 * 2755 * FINDBLK_REF - Returns the buffer ref'd, which prevents normal 2756 * reuse by getnewbuf() but does not prevent 2757 * disassociation (B_INVAL). Used to avoid deadlocks 2758 * against random (vp,loffset)s due to reassignment. 2759 * 2760 * (0) - Lock the buffer blocking. 2761 * 2762 * MPSAFE 2763 */ 2764 struct buf * 2765 findblk(struct vnode *vp, off_t loffset, int flags) 2766 { 2767 struct buf *bp; 2768 int lkflags; 2769 2770 lkflags = LK_EXCLUSIVE; 2771 if (flags & FINDBLK_NBLOCK) 2772 lkflags |= LK_NOWAIT; 2773 2774 for (;;) { 2775 /* 2776 * Lookup. Ref the buf while holding v_token to prevent 2777 * reuse (but does not prevent diassociation). 2778 */ 2779 lwkt_gettoken_shared(&vp->v_token); 2780 bp = buf_rb_hash_RB_LOOKUP(&vp->v_rbhash_tree, loffset); 2781 if (bp == NULL) { 2782 lwkt_reltoken(&vp->v_token); 2783 return(NULL); 2784 } 2785 bqhold(bp); 2786 lwkt_reltoken(&vp->v_token); 2787 2788 /* 2789 * If testing only break and return bp, do not lock. 2790 */ 2791 if (flags & FINDBLK_TEST) 2792 break; 2793 2794 /* 2795 * Lock the buffer, return an error if the lock fails. 2796 * (only FINDBLK_NBLOCK can cause the lock to fail). 2797 */ 2798 if (BUF_LOCK(bp, lkflags)) { 2799 atomic_subtract_int(&bp->b_refs, 1); 2800 /* bp = NULL; not needed */ 2801 return(NULL); 2802 } 2803 2804 /* 2805 * Revalidate the locked buf before allowing it to be 2806 * returned. 2807 */ 2808 if (bp->b_vp == vp && bp->b_loffset == loffset) 2809 break; 2810 atomic_subtract_int(&bp->b_refs, 1); 2811 BUF_UNLOCK(bp); 2812 } 2813 2814 /* 2815 * Success 2816 */ 2817 if ((flags & FINDBLK_REF) == 0) 2818 atomic_subtract_int(&bp->b_refs, 1); 2819 return(bp); 2820 } 2821 2822 /* 2823 * getcacheblk: 2824 * 2825 * Similar to getblk() except only returns the buffer if it is 2826 * B_CACHE and requires no other manipulation. Otherwise NULL 2827 * is returned. 2828 * 2829 * If B_RAM is set the buffer might be just fine, but we return 2830 * NULL anyway because we want the code to fall through to the 2831 * cluster read. Otherwise read-ahead breaks. 2832 * 2833 * If blksize is 0 the buffer cache buffer must already be fully 2834 * cached. 2835 * 2836 * If blksize is non-zero getblk() will be used, allowing a buffer 2837 * to be reinstantiated from its VM backing store. The buffer must 2838 * still be fully cached after reinstantiation to be returned. 2839 */ 2840 struct buf * 2841 getcacheblk(struct vnode *vp, off_t loffset, int blksize) 2842 { 2843 struct buf *bp; 2844 2845 if (blksize) { 2846 bp = getblk(vp, loffset, blksize, 0, 0); 2847 if (bp) { 2848 if ((bp->b_flags & (B_INVAL | B_CACHE | B_RAM)) == 2849 B_CACHE) { 2850 bp->b_flags &= ~B_AGE; 2851 } else { 2852 brelse(bp); 2853 bp = NULL; 2854 } 2855 } 2856 } else { 2857 bp = findblk(vp, loffset, 0); 2858 if (bp) { 2859 if ((bp->b_flags & (B_INVAL | B_CACHE | B_RAM)) == 2860 B_CACHE) { 2861 bp->b_flags &= ~B_AGE; 2862 bremfree(bp); 2863 } else { 2864 BUF_UNLOCK(bp); 2865 bp = NULL; 2866 } 2867 } 2868 } 2869 return (bp); 2870 } 2871 2872 /* 2873 * getblk: 2874 * 2875 * Get a block given a specified block and offset into a file/device. 2876 * B_INVAL may or may not be set on return. The caller should clear 2877 * B_INVAL prior to initiating a READ. 2878 * 2879 * IT IS IMPORTANT TO UNDERSTAND THAT IF YOU CALL GETBLK() AND B_CACHE 2880 * IS NOT SET, YOU MUST INITIALIZE THE RETURNED BUFFER, ISSUE A READ, 2881 * OR SET B_INVAL BEFORE RETIRING IT. If you retire a getblk'd buffer 2882 * without doing any of those things the system will likely believe 2883 * the buffer to be valid (especially if it is not B_VMIO), and the 2884 * next getblk() will return the buffer with B_CACHE set. 2885 * 2886 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2887 * an existing buffer. 2888 * 2889 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2890 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2891 * and then cleared based on the backing VM. If the previous buffer is 2892 * non-0-sized but invalid, B_CACHE will be cleared. 2893 * 2894 * If getblk() must create a new buffer, the new buffer is returned with 2895 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2896 * case it is returned with B_INVAL clear and B_CACHE set based on the 2897 * backing VM. 2898 * 2899 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 2900 * B_CACHE bit is clear. 2901 * 2902 * What this means, basically, is that the caller should use B_CACHE to 2903 * determine whether the buffer is fully valid or not and should clear 2904 * B_INVAL prior to issuing a read. If the caller intends to validate 2905 * the buffer by loading its data area with something, the caller needs 2906 * to clear B_INVAL. If the caller does this without issuing an I/O, 2907 * the caller should set B_CACHE ( as an optimization ), else the caller 2908 * should issue the I/O and biodone() will set B_CACHE if the I/O was 2909 * a write attempt or if it was a successfull read. If the caller 2910 * intends to issue a READ, the caller must clear B_INVAL and B_ERROR 2911 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 2912 * 2913 * getblk flags: 2914 * 2915 * GETBLK_PCATCH - catch signal if blocked, can cause NULL return 2916 * GETBLK_BHEAVY - heavy-weight buffer cache buffer 2917 * 2918 * MPALMOSTSAFE 2919 */ 2920 struct buf * 2921 getblk(struct vnode *vp, off_t loffset, int size, int blkflags, int slptimeo) 2922 { 2923 struct buf *bp; 2924 int slpflags = (blkflags & GETBLK_PCATCH) ? PCATCH : 0; 2925 int error; 2926 int lkflags; 2927 2928 if (size > MAXBSIZE) 2929 panic("getblk: size(%d) > MAXBSIZE(%d)", size, MAXBSIZE); 2930 if (vp->v_object == NULL) 2931 panic("getblk: vnode %p has no object!", vp); 2932 2933 loop: 2934 if ((bp = findblk(vp, loffset, FINDBLK_REF | FINDBLK_TEST)) != NULL) { 2935 /* 2936 * The buffer was found in the cache, but we need to lock it. 2937 * We must acquire a ref on the bp to prevent reuse, but 2938 * this will not prevent disassociation (brelvp()) so we 2939 * must recheck (vp,loffset) after acquiring the lock. 2940 * 2941 * Without the ref the buffer could potentially be reused 2942 * before we acquire the lock and create a deadlock 2943 * situation between the thread trying to reuse the buffer 2944 * and us due to the fact that we would wind up blocking 2945 * on a random (vp,loffset). 2946 */ 2947 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) { 2948 if (blkflags & GETBLK_NOWAIT) { 2949 bqdrop(bp); 2950 return(NULL); 2951 } 2952 lkflags = LK_EXCLUSIVE | LK_SLEEPFAIL; 2953 if (blkflags & GETBLK_PCATCH) 2954 lkflags |= LK_PCATCH; 2955 error = BUF_TIMELOCK(bp, lkflags, "getblk", slptimeo); 2956 if (error) { 2957 bqdrop(bp); 2958 if (error == ENOLCK) 2959 goto loop; 2960 return (NULL); 2961 } 2962 /* buffer may have changed on us */ 2963 } 2964 bqdrop(bp); 2965 2966 /* 2967 * Once the buffer has been locked, make sure we didn't race 2968 * a buffer recyclement. Buffers that are no longer hashed 2969 * will have b_vp == NULL, so this takes care of that check 2970 * as well. 2971 */ 2972 if (bp->b_vp != vp || bp->b_loffset != loffset) { 2973 kprintf("Warning buffer %p (vp %p loffset %lld) " 2974 "was recycled\n", 2975 bp, vp, (long long)loffset); 2976 BUF_UNLOCK(bp); 2977 goto loop; 2978 } 2979 2980 /* 2981 * If SZMATCH any pre-existing buffer must be of the requested 2982 * size or NULL is returned. The caller absolutely does not 2983 * want getblk() to bwrite() the buffer on a size mismatch. 2984 */ 2985 if ((blkflags & GETBLK_SZMATCH) && size != bp->b_bcount) { 2986 BUF_UNLOCK(bp); 2987 return(NULL); 2988 } 2989 2990 /* 2991 * All vnode-based buffers must be backed by a VM object. 2992 */ 2993 KKASSERT(bp->b_flags & B_VMIO); 2994 KKASSERT(bp->b_cmd == BUF_CMD_DONE); 2995 bp->b_flags &= ~B_AGE; 2996 2997 /* 2998 * Make sure that B_INVAL buffers do not have a cached 2999 * block number translation. 3000 */ 3001 if ((bp->b_flags & B_INVAL) && (bp->b_bio2.bio_offset != NOOFFSET)) { 3002 kprintf("Warning invalid buffer %p (vp %p loffset %lld)" 3003 " did not have cleared bio_offset cache\n", 3004 bp, vp, (long long)loffset); 3005 clearbiocache(&bp->b_bio2); 3006 } 3007 3008 /* 3009 * The buffer is locked. B_CACHE is cleared if the buffer is 3010 * invalid. 3011 */ 3012 if (bp->b_flags & B_INVAL) 3013 bp->b_flags &= ~B_CACHE; 3014 bremfree(bp); 3015 3016 /* 3017 * Any size inconsistancy with a dirty buffer or a buffer 3018 * with a softupdates dependancy must be resolved. Resizing 3019 * the buffer in such circumstances can lead to problems. 3020 * 3021 * Dirty or dependant buffers are written synchronously. 3022 * Other types of buffers are simply released and 3023 * reconstituted as they may be backed by valid, dirty VM 3024 * pages (but not marked B_DELWRI). 3025 * 3026 * NFS NOTE: NFS buffers which straddle EOF are oddly-sized 3027 * and may be left over from a prior truncation (and thus 3028 * no longer represent the actual EOF point), so we 3029 * definitely do not want to B_NOCACHE the backing store. 3030 */ 3031 if (size != bp->b_bcount) { 3032 if (bp->b_flags & B_DELWRI) { 3033 bp->b_flags |= B_RELBUF; 3034 bwrite(bp); 3035 } else if (LIST_FIRST(&bp->b_dep)) { 3036 bp->b_flags |= B_RELBUF; 3037 bwrite(bp); 3038 } else { 3039 bp->b_flags |= B_RELBUF; 3040 brelse(bp); 3041 } 3042 goto loop; 3043 } 3044 KKASSERT(size <= bp->b_kvasize); 3045 KASSERT(bp->b_loffset != NOOFFSET, 3046 ("getblk: no buffer offset")); 3047 3048 /* 3049 * A buffer with B_DELWRI set and B_CACHE clear must 3050 * be committed before we can return the buffer in 3051 * order to prevent the caller from issuing a read 3052 * ( due to B_CACHE not being set ) and overwriting 3053 * it. 3054 * 3055 * Most callers, including NFS and FFS, need this to 3056 * operate properly either because they assume they 3057 * can issue a read if B_CACHE is not set, or because 3058 * ( for example ) an uncached B_DELWRI might loop due 3059 * to softupdates re-dirtying the buffer. In the latter 3060 * case, B_CACHE is set after the first write completes, 3061 * preventing further loops. 3062 * 3063 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 3064 * above while extending the buffer, we cannot allow the 3065 * buffer to remain with B_CACHE set after the write 3066 * completes or it will represent a corrupt state. To 3067 * deal with this we set B_NOCACHE to scrap the buffer 3068 * after the write. 3069 * 3070 * XXX Should this be B_RELBUF instead of B_NOCACHE? 3071 * I'm not even sure this state is still possible 3072 * now that getblk() writes out any dirty buffers 3073 * on size changes. 3074 * 3075 * We might be able to do something fancy, like setting 3076 * B_CACHE in bwrite() except if B_DELWRI is already set, 3077 * so the below call doesn't set B_CACHE, but that gets real 3078 * confusing. This is much easier. 3079 */ 3080 3081 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 3082 kprintf("getblk: Warning, bp %p loff=%jx DELWRI set " 3083 "and CACHE clear, b_flags %08x\n", 3084 bp, (intmax_t)bp->b_loffset, bp->b_flags); 3085 bp->b_flags |= B_NOCACHE; 3086 bwrite(bp); 3087 goto loop; 3088 } 3089 } else { 3090 /* 3091 * Buffer is not in-core, create new buffer. The buffer 3092 * returned by getnewbuf() is locked. Note that the returned 3093 * buffer is also considered valid (not marked B_INVAL). 3094 * 3095 * Calculating the offset for the I/O requires figuring out 3096 * the block size. We use DEV_BSIZE for VBLK or VCHR and 3097 * the mount's f_iosize otherwise. If the vnode does not 3098 * have an associated mount we assume that the passed size is 3099 * the block size. 3100 * 3101 * Note that vn_isdisk() cannot be used here since it may 3102 * return a failure for numerous reasons. Note that the 3103 * buffer size may be larger then the block size (the caller 3104 * will use block numbers with the proper multiple). Beware 3105 * of using any v_* fields which are part of unions. In 3106 * particular, in DragonFly the mount point overloading 3107 * mechanism uses the namecache only and the underlying 3108 * directory vnode is not a special case. 3109 */ 3110 int bsize, maxsize; 3111 3112 if (vp->v_type == VBLK || vp->v_type == VCHR) 3113 bsize = DEV_BSIZE; 3114 else if (vp->v_mount) 3115 bsize = vp->v_mount->mnt_stat.f_iosize; 3116 else 3117 bsize = size; 3118 3119 maxsize = size + (loffset & PAGE_MASK); 3120 maxsize = imax(maxsize, bsize); 3121 3122 bp = getnewbuf(blkflags, slptimeo, size, maxsize); 3123 if (bp == NULL) { 3124 if (slpflags || slptimeo) 3125 return NULL; 3126 goto loop; 3127 } 3128 3129 /* 3130 * Atomically insert the buffer into the hash, so that it can 3131 * be found by findblk(). 3132 * 3133 * If bgetvp() returns non-zero a collision occured, and the 3134 * bp will not be associated with the vnode. 3135 * 3136 * Make sure the translation layer has been cleared. 3137 */ 3138 bp->b_loffset = loffset; 3139 bp->b_bio2.bio_offset = NOOFFSET; 3140 /* bp->b_bio2.bio_next = NULL; */ 3141 3142 if (bgetvp(vp, bp, size)) { 3143 bp->b_flags |= B_INVAL; 3144 brelse(bp); 3145 goto loop; 3146 } 3147 3148 /* 3149 * All vnode-based buffers must be backed by a VM object. 3150 */ 3151 KKASSERT(vp->v_object != NULL); 3152 bp->b_flags |= B_VMIO; 3153 KKASSERT(bp->b_cmd == BUF_CMD_DONE); 3154 3155 allocbuf(bp, size); 3156 } 3157 KKASSERT(dsched_is_clear_buf_priv(bp)); 3158 return (bp); 3159 } 3160 3161 /* 3162 * regetblk(bp) 3163 * 3164 * Reacquire a buffer that was previously released to the locked queue, 3165 * or reacquire a buffer which is interlocked by having bioops->io_deallocate 3166 * set B_LOCKED (which handles the acquisition race). 3167 * 3168 * To this end, either B_LOCKED must be set or the dependancy list must be 3169 * non-empty. 3170 * 3171 * MPSAFE 3172 */ 3173 void 3174 regetblk(struct buf *bp) 3175 { 3176 KKASSERT((bp->b_flags & B_LOCKED) || LIST_FIRST(&bp->b_dep) != NULL); 3177 BUF_LOCK(bp, LK_EXCLUSIVE | LK_RETRY); 3178 bremfree(bp); 3179 } 3180 3181 /* 3182 * geteblk: 3183 * 3184 * Get an empty, disassociated buffer of given size. The buffer is 3185 * initially set to B_INVAL. 3186 * 3187 * critical section protection is not required for the allocbuf() 3188 * call because races are impossible here. 3189 * 3190 * MPALMOSTSAFE 3191 */ 3192 struct buf * 3193 geteblk(int size) 3194 { 3195 struct buf *bp; 3196 int maxsize; 3197 3198 maxsize = (size + BKVAMASK) & ~BKVAMASK; 3199 3200 while ((bp = getnewbuf(0, 0, size, maxsize)) == NULL) 3201 ; 3202 allocbuf(bp, size); 3203 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 3204 KKASSERT(dsched_is_clear_buf_priv(bp)); 3205 return (bp); 3206 } 3207 3208 3209 /* 3210 * allocbuf: 3211 * 3212 * This code constitutes the buffer memory from either anonymous system 3213 * memory (in the case of non-VMIO operations) or from an associated 3214 * VM object (in the case of VMIO operations). This code is able to 3215 * resize a buffer up or down. 3216 * 3217 * Note that this code is tricky, and has many complications to resolve 3218 * deadlock or inconsistant data situations. Tread lightly!!! 3219 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 3220 * the caller. Calling this code willy nilly can result in the loss of 3221 * data. 3222 * 3223 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 3224 * B_CACHE for the non-VMIO case. 3225 * 3226 * This routine does not need to be called from a critical section but you 3227 * must own the buffer. 3228 * 3229 * MPSAFE 3230 */ 3231 int 3232 allocbuf(struct buf *bp, int size) 3233 { 3234 int newbsize, mbsize; 3235 int i; 3236 3237 if (BUF_REFCNT(bp) == 0) 3238 panic("allocbuf: buffer not busy"); 3239 3240 if (bp->b_kvasize < size) 3241 panic("allocbuf: buffer too small"); 3242 3243 if ((bp->b_flags & B_VMIO) == 0) { 3244 caddr_t origbuf; 3245 int origbufsize; 3246 /* 3247 * Just get anonymous memory from the kernel. Don't 3248 * mess with B_CACHE. 3249 */ 3250 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3251 if (bp->b_flags & B_MALLOC) 3252 newbsize = mbsize; 3253 else 3254 newbsize = round_page(size); 3255 3256 if (newbsize < bp->b_bufsize) { 3257 /* 3258 * Malloced buffers are not shrunk 3259 */ 3260 if (bp->b_flags & B_MALLOC) { 3261 if (newbsize) { 3262 bp->b_bcount = size; 3263 } else { 3264 kfree(bp->b_data, M_BIOBUF); 3265 if (bp->b_bufsize) { 3266 atomic_subtract_long(&bufmallocspace, bp->b_bufsize); 3267 bufspacewakeup(); 3268 bp->b_bufsize = 0; 3269 } 3270 bp->b_data = bp->b_kvabase; 3271 bp->b_bcount = 0; 3272 bp->b_flags &= ~B_MALLOC; 3273 } 3274 return 1; 3275 } 3276 vm_hold_free_pages( 3277 bp, 3278 (vm_offset_t) bp->b_data + newbsize, 3279 (vm_offset_t) bp->b_data + bp->b_bufsize); 3280 } else if (newbsize > bp->b_bufsize) { 3281 /* 3282 * We only use malloced memory on the first allocation. 3283 * and revert to page-allocated memory when the buffer 3284 * grows. 3285 */ 3286 if ((bufmallocspace < maxbufmallocspace) && 3287 (bp->b_bufsize == 0) && 3288 (mbsize <= PAGE_SIZE/2)) { 3289 3290 bp->b_data = kmalloc(mbsize, M_BIOBUF, M_WAITOK); 3291 bp->b_bufsize = mbsize; 3292 bp->b_bcount = size; 3293 bp->b_flags |= B_MALLOC; 3294 atomic_add_long(&bufmallocspace, mbsize); 3295 return 1; 3296 } 3297 origbuf = NULL; 3298 origbufsize = 0; 3299 /* 3300 * If the buffer is growing on its other-than-first 3301 * allocation, then we revert to the page-allocation 3302 * scheme. 3303 */ 3304 if (bp->b_flags & B_MALLOC) { 3305 origbuf = bp->b_data; 3306 origbufsize = bp->b_bufsize; 3307 bp->b_data = bp->b_kvabase; 3308 if (bp->b_bufsize) { 3309 atomic_subtract_long(&bufmallocspace, 3310 bp->b_bufsize); 3311 bufspacewakeup(); 3312 bp->b_bufsize = 0; 3313 } 3314 bp->b_flags &= ~B_MALLOC; 3315 newbsize = round_page(newbsize); 3316 } 3317 vm_hold_load_pages( 3318 bp, 3319 (vm_offset_t) bp->b_data + bp->b_bufsize, 3320 (vm_offset_t) bp->b_data + newbsize); 3321 if (origbuf) { 3322 bcopy(origbuf, bp->b_data, origbufsize); 3323 kfree(origbuf, M_BIOBUF); 3324 } 3325 } 3326 } else { 3327 vm_page_t m; 3328 int desiredpages; 3329 3330 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3331 desiredpages = ((int)(bp->b_loffset & PAGE_MASK) + 3332 newbsize + PAGE_MASK) >> PAGE_SHIFT; 3333 KKASSERT(desiredpages <= XIO_INTERNAL_PAGES); 3334 3335 if (bp->b_flags & B_MALLOC) 3336 panic("allocbuf: VMIO buffer can't be malloced"); 3337 /* 3338 * Set B_CACHE initially if buffer is 0 length or will become 3339 * 0-length. 3340 */ 3341 if (size == 0 || bp->b_bufsize == 0) 3342 bp->b_flags |= B_CACHE; 3343 3344 if (newbsize < bp->b_bufsize) { 3345 /* 3346 * DEV_BSIZE aligned new buffer size is less then the 3347 * DEV_BSIZE aligned existing buffer size. Figure out 3348 * if we have to remove any pages. 3349 */ 3350 if (desiredpages < bp->b_xio.xio_npages) { 3351 for (i = desiredpages; i < bp->b_xio.xio_npages; i++) { 3352 /* 3353 * the page is not freed here -- it 3354 * is the responsibility of 3355 * vnode_pager_setsize 3356 */ 3357 m = bp->b_xio.xio_pages[i]; 3358 KASSERT(m != bogus_page, 3359 ("allocbuf: bogus page found")); 3360 vm_page_busy_wait(m, TRUE, "biodep"); 3361 bp->b_xio.xio_pages[i] = NULL; 3362 vm_page_unwire(m, 0); 3363 vm_page_wakeup(m); 3364 } 3365 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) + 3366 (desiredpages << PAGE_SHIFT), (bp->b_xio.xio_npages - desiredpages)); 3367 bp->b_xio.xio_npages = desiredpages; 3368 } 3369 } else if (size > bp->b_bcount) { 3370 /* 3371 * We are growing the buffer, possibly in a 3372 * byte-granular fashion. 3373 */ 3374 struct vnode *vp; 3375 vm_object_t obj; 3376 vm_offset_t toff; 3377 vm_offset_t tinc; 3378 3379 /* 3380 * Step 1, bring in the VM pages from the object, 3381 * allocating them if necessary. We must clear 3382 * B_CACHE if these pages are not valid for the 3383 * range covered by the buffer. 3384 * 3385 * critical section protection is required to protect 3386 * against interrupts unbusying and freeing pages 3387 * between our vm_page_lookup() and our 3388 * busycheck/wiring call. 3389 */ 3390 vp = bp->b_vp; 3391 obj = vp->v_object; 3392 3393 vm_object_hold(obj); 3394 while (bp->b_xio.xio_npages < desiredpages) { 3395 vm_page_t m; 3396 vm_pindex_t pi; 3397 int error; 3398 3399 pi = OFF_TO_IDX(bp->b_loffset) + 3400 bp->b_xio.xio_npages; 3401 3402 /* 3403 * Blocking on m->busy might lead to a 3404 * deadlock: 3405 * 3406 * vm_fault->getpages->cluster_read->allocbuf 3407 */ 3408 m = vm_page_lookup_busy_try(obj, pi, FALSE, 3409 &error); 3410 if (error) { 3411 vm_page_sleep_busy(m, FALSE, "pgtblk"); 3412 continue; 3413 } 3414 if (m == NULL) { 3415 /* 3416 * note: must allocate system pages 3417 * since blocking here could intefere 3418 * with paging I/O, no matter which 3419 * process we are. 3420 */ 3421 m = bio_page_alloc(obj, pi, desiredpages - bp->b_xio.xio_npages); 3422 if (m) { 3423 vm_page_wire(m); 3424 vm_page_flag_clear(m, PG_ZERO); 3425 vm_page_wakeup(m); 3426 bp->b_flags &= ~B_CACHE; 3427 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 3428 ++bp->b_xio.xio_npages; 3429 } 3430 continue; 3431 } 3432 3433 /* 3434 * We found a page and were able to busy it. 3435 */ 3436 vm_page_flag_clear(m, PG_ZERO); 3437 vm_page_wire(m); 3438 vm_page_wakeup(m); 3439 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 3440 ++bp->b_xio.xio_npages; 3441 if (bp->b_act_count < m->act_count) 3442 bp->b_act_count = m->act_count; 3443 } 3444 vm_object_drop(obj); 3445 3446 /* 3447 * Step 2. We've loaded the pages into the buffer, 3448 * we have to figure out if we can still have B_CACHE 3449 * set. Note that B_CACHE is set according to the 3450 * byte-granular range ( bcount and size ), not the 3451 * aligned range ( newbsize ). 3452 * 3453 * The VM test is against m->valid, which is DEV_BSIZE 3454 * aligned. Needless to say, the validity of the data 3455 * needs to also be DEV_BSIZE aligned. Note that this 3456 * fails with NFS if the server or some other client 3457 * extends the file's EOF. If our buffer is resized, 3458 * B_CACHE may remain set! XXX 3459 */ 3460 3461 toff = bp->b_bcount; 3462 tinc = PAGE_SIZE - ((bp->b_loffset + toff) & PAGE_MASK); 3463 3464 while ((bp->b_flags & B_CACHE) && toff < size) { 3465 vm_pindex_t pi; 3466 3467 if (tinc > (size - toff)) 3468 tinc = size - toff; 3469 3470 pi = ((bp->b_loffset & PAGE_MASK) + toff) >> 3471 PAGE_SHIFT; 3472 3473 vfs_buf_test_cache( 3474 bp, 3475 bp->b_loffset, 3476 toff, 3477 tinc, 3478 bp->b_xio.xio_pages[pi] 3479 ); 3480 toff += tinc; 3481 tinc = PAGE_SIZE; 3482 } 3483 3484 /* 3485 * Step 3, fixup the KVM pmap. Remember that 3486 * bp->b_data is relative to bp->b_loffset, but 3487 * bp->b_loffset may be offset into the first page. 3488 */ 3489 3490 bp->b_data = (caddr_t) 3491 trunc_page((vm_offset_t)bp->b_data); 3492 pmap_qenter( 3493 (vm_offset_t)bp->b_data, 3494 bp->b_xio.xio_pages, 3495 bp->b_xio.xio_npages 3496 ); 3497 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 3498 (vm_offset_t)(bp->b_loffset & PAGE_MASK)); 3499 } 3500 } 3501 3502 /* adjust space use on already-dirty buffer */ 3503 if (bp->b_flags & B_DELWRI) { 3504 spin_lock(&bufcspin); 3505 dirtybufspace += newbsize - bp->b_bufsize; 3506 if (bp->b_flags & B_HEAVY) 3507 dirtybufspacehw += newbsize - bp->b_bufsize; 3508 spin_unlock(&bufcspin); 3509 } 3510 if (newbsize < bp->b_bufsize) 3511 bufspacewakeup(); 3512 bp->b_bufsize = newbsize; /* actual buffer allocation */ 3513 bp->b_bcount = size; /* requested buffer size */ 3514 return 1; 3515 } 3516 3517 /* 3518 * biowait: 3519 * 3520 * Wait for buffer I/O completion, returning error status. B_EINTR 3521 * is converted into an EINTR error but not cleared (since a chain 3522 * of biowait() calls may occur). 3523 * 3524 * On return bpdone() will have been called but the buffer will remain 3525 * locked and will not have been brelse()'d. 3526 * 3527 * NOTE! If a timeout is specified and ETIMEDOUT occurs the I/O is 3528 * likely still in progress on return. 3529 * 3530 * NOTE! This operation is on a BIO, not a BUF. 3531 * 3532 * NOTE! BIO_DONE is cleared by vn_strategy() 3533 * 3534 * MPSAFE 3535 */ 3536 static __inline int 3537 _biowait(struct bio *bio, const char *wmesg, int to) 3538 { 3539 struct buf *bp = bio->bio_buf; 3540 u_int32_t flags; 3541 u_int32_t nflags; 3542 int error; 3543 3544 KKASSERT(bio == &bp->b_bio1); 3545 for (;;) { 3546 flags = bio->bio_flags; 3547 if (flags & BIO_DONE) 3548 break; 3549 nflags = flags | BIO_WANT; 3550 tsleep_interlock(bio, 0); 3551 if (atomic_cmpset_int(&bio->bio_flags, flags, nflags)) { 3552 if (wmesg) 3553 error = tsleep(bio, PINTERLOCKED, wmesg, to); 3554 else if (bp->b_cmd == BUF_CMD_READ) 3555 error = tsleep(bio, PINTERLOCKED, "biord", to); 3556 else 3557 error = tsleep(bio, PINTERLOCKED, "biowr", to); 3558 if (error) { 3559 kprintf("tsleep error biowait %d\n", error); 3560 return (error); 3561 } 3562 } 3563 } 3564 3565 /* 3566 * Finish up. 3567 */ 3568 KKASSERT(bp->b_cmd == BUF_CMD_DONE); 3569 bio->bio_flags &= ~(BIO_DONE | BIO_SYNC); 3570 if (bp->b_flags & B_EINTR) 3571 return (EINTR); 3572 if (bp->b_flags & B_ERROR) 3573 return (bp->b_error ? bp->b_error : EIO); 3574 return (0); 3575 } 3576 3577 int 3578 biowait(struct bio *bio, const char *wmesg) 3579 { 3580 return(_biowait(bio, wmesg, 0)); 3581 } 3582 3583 int 3584 biowait_timeout(struct bio *bio, const char *wmesg, int to) 3585 { 3586 return(_biowait(bio, wmesg, to)); 3587 } 3588 3589 /* 3590 * This associates a tracking count with an I/O. vn_strategy() and 3591 * dev_dstrategy() do this automatically but there are a few cases 3592 * where a vnode or device layer is bypassed when a block translation 3593 * is cached. In such cases bio_start_transaction() may be called on 3594 * the bypassed layers so the system gets an I/O in progress indication 3595 * for those higher layers. 3596 */ 3597 void 3598 bio_start_transaction(struct bio *bio, struct bio_track *track) 3599 { 3600 bio->bio_track = track; 3601 if (dsched_is_clear_buf_priv(bio->bio_buf)) 3602 dsched_new_buf(bio->bio_buf); 3603 bio_track_ref(track); 3604 } 3605 3606 /* 3607 * Initiate I/O on a vnode. 3608 * 3609 * SWAPCACHE OPERATION: 3610 * 3611 * Real buffer cache buffers have a non-NULL bp->b_vp. Unfortunately 3612 * devfs also uses b_vp for fake buffers so we also have to check 3613 * that B_PAGING is 0. In this case the passed 'vp' is probably the 3614 * underlying block device. The swap assignments are related to the 3615 * buffer cache buffer's b_vp, not the passed vp. 3616 * 3617 * The passed vp == bp->b_vp only in the case where the strategy call 3618 * is made on the vp itself for its own buffers (a regular file or 3619 * block device vp). The filesystem usually then re-calls vn_strategy() 3620 * after translating the request to an underlying device. 3621 * 3622 * Cluster buffers set B_CLUSTER and the passed vp is the vp of the 3623 * underlying buffer cache buffers. 3624 * 3625 * We can only deal with page-aligned buffers at the moment, because 3626 * we can't tell what the real dirty state for pages straddling a buffer 3627 * are. 3628 * 3629 * In order to call swap_pager_strategy() we must provide the VM object 3630 * and base offset for the underlying buffer cache pages so it can find 3631 * the swap blocks. 3632 */ 3633 void 3634 vn_strategy(struct vnode *vp, struct bio *bio) 3635 { 3636 struct bio_track *track; 3637 struct buf *bp = bio->bio_buf; 3638 3639 KKASSERT(bp->b_cmd != BUF_CMD_DONE); 3640 3641 /* 3642 * Set when an I/O is issued on the bp. Cleared by consumers 3643 * (aka HAMMER), allowing the consumer to determine if I/O had 3644 * actually occurred. 3645 */ 3646 bp->b_flags |= B_IODEBUG; 3647 3648 /* 3649 * Handle the swap cache intercept. 3650 */ 3651 if (vn_cache_strategy(vp, bio)) 3652 return; 3653 3654 /* 3655 * Otherwise do the operation through the filesystem 3656 */ 3657 if (bp->b_cmd == BUF_CMD_READ) 3658 track = &vp->v_track_read; 3659 else 3660 track = &vp->v_track_write; 3661 KKASSERT((bio->bio_flags & BIO_DONE) == 0); 3662 bio->bio_track = track; 3663 if (dsched_is_clear_buf_priv(bio->bio_buf)) 3664 dsched_new_buf(bio->bio_buf); 3665 bio_track_ref(track); 3666 vop_strategy(*vp->v_ops, vp, bio); 3667 } 3668 3669 static void vn_cache_strategy_callback(struct bio *bio); 3670 3671 int 3672 vn_cache_strategy(struct vnode *vp, struct bio *bio) 3673 { 3674 struct buf *bp = bio->bio_buf; 3675 struct bio *nbio; 3676 vm_object_t object; 3677 vm_page_t m; 3678 int i; 3679 3680 /* 3681 * Is this buffer cache buffer suitable for reading from 3682 * the swap cache? 3683 */ 3684 if (vm_swapcache_read_enable == 0 || 3685 bp->b_cmd != BUF_CMD_READ || 3686 ((bp->b_flags & B_CLUSTER) == 0 && 3687 (bp->b_vp == NULL || (bp->b_flags & B_PAGING))) || 3688 ((int)bp->b_loffset & PAGE_MASK) != 0 || 3689 (bp->b_bcount & PAGE_MASK) != 0) { 3690 return(0); 3691 } 3692 3693 /* 3694 * Figure out the original VM object (it will match the underlying 3695 * VM pages). Note that swap cached data uses page indices relative 3696 * to that object, not relative to bio->bio_offset. 3697 */ 3698 if (bp->b_flags & B_CLUSTER) 3699 object = vp->v_object; 3700 else 3701 object = bp->b_vp->v_object; 3702 3703 /* 3704 * In order to be able to use the swap cache all underlying VM 3705 * pages must be marked as such, and we can't have any bogus pages. 3706 */ 3707 for (i = 0; i < bp->b_xio.xio_npages; ++i) { 3708 m = bp->b_xio.xio_pages[i]; 3709 if ((m->flags & PG_SWAPPED) == 0) 3710 break; 3711 if (m == bogus_page) 3712 break; 3713 } 3714 3715 /* 3716 * If we are good then issue the I/O using swap_pager_strategy(). 3717 * 3718 * We can only do this if the buffer actually supports object-backed 3719 * I/O. If it doesn't npages will be 0. 3720 */ 3721 if (i && i == bp->b_xio.xio_npages) { 3722 m = bp->b_xio.xio_pages[0]; 3723 nbio = push_bio(bio); 3724 nbio->bio_done = vn_cache_strategy_callback; 3725 nbio->bio_offset = ptoa(m->pindex); 3726 KKASSERT(m->object == object); 3727 swap_pager_strategy(object, nbio); 3728 return(1); 3729 } 3730 return(0); 3731 } 3732 3733 /* 3734 * This is a bit of a hack but since the vn_cache_strategy() function can 3735 * override a VFS's strategy function we must make sure that the bio, which 3736 * is probably bio2, doesn't leak an unexpected offset value back to the 3737 * filesystem. The filesystem (e.g. UFS) might otherwise assume that the 3738 * bio went through its own file strategy function and the the bio2 offset 3739 * is a cached disk offset when, in fact, it isn't. 3740 */ 3741 static void 3742 vn_cache_strategy_callback(struct bio *bio) 3743 { 3744 bio->bio_offset = NOOFFSET; 3745 biodone(pop_bio(bio)); 3746 } 3747 3748 /* 3749 * bpdone: 3750 * 3751 * Finish I/O on a buffer after all BIOs have been processed. 3752 * Called when the bio chain is exhausted or by biowait. If called 3753 * by biowait, elseit is typically 0. 3754 * 3755 * bpdone is also responsible for setting B_CACHE in a B_VMIO bp. 3756 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3757 * assuming B_INVAL is clear. 3758 * 3759 * For the VMIO case, we set B_CACHE if the op was a read and no 3760 * read error occured, or if the op was a write. B_CACHE is never 3761 * set if the buffer is invalid or otherwise uncacheable. 3762 * 3763 * bpdone does not mess with B_INVAL, allowing the I/O routine or the 3764 * initiator to leave B_INVAL set to brelse the buffer out of existance 3765 * in the biodone routine. 3766 */ 3767 void 3768 bpdone(struct buf *bp, int elseit) 3769 { 3770 buf_cmd_t cmd; 3771 3772 KASSERT(BUF_REFCNTNB(bp) > 0, 3773 ("biodone: bp %p not busy %d", bp, BUF_REFCNTNB(bp))); 3774 KASSERT(bp->b_cmd != BUF_CMD_DONE, 3775 ("biodone: bp %p already done!", bp)); 3776 3777 /* 3778 * No more BIOs are left. All completion functions have been dealt 3779 * with, now we clean up the buffer. 3780 */ 3781 cmd = bp->b_cmd; 3782 bp->b_cmd = BUF_CMD_DONE; 3783 3784 /* 3785 * Only reads and writes are processed past this point. 3786 */ 3787 if (cmd != BUF_CMD_READ && cmd != BUF_CMD_WRITE) { 3788 if (cmd == BUF_CMD_FREEBLKS) 3789 bp->b_flags |= B_NOCACHE; 3790 if (elseit) 3791 brelse(bp); 3792 return; 3793 } 3794 3795 /* 3796 * Warning: softupdates may re-dirty the buffer, and HAMMER can do 3797 * a lot worse. XXX - move this above the clearing of b_cmd 3798 */ 3799 if (LIST_FIRST(&bp->b_dep) != NULL) 3800 buf_complete(bp); /* MPSAFE */ 3801 3802 /* 3803 * A failed write must re-dirty the buffer unless B_INVAL 3804 * was set. Only applicable to normal buffers (with VPs). 3805 * vinum buffers may not have a vp. 3806 */ 3807 if (cmd == BUF_CMD_WRITE && 3808 (bp->b_flags & (B_ERROR | B_INVAL)) == B_ERROR) { 3809 bp->b_flags &= ~B_NOCACHE; 3810 if (bp->b_vp) 3811 bdirty(bp); 3812 } 3813 3814 if (bp->b_flags & B_VMIO) { 3815 int i; 3816 vm_ooffset_t foff; 3817 vm_page_t m; 3818 vm_object_t obj; 3819 int iosize; 3820 struct vnode *vp = bp->b_vp; 3821 3822 obj = vp->v_object; 3823 3824 #if defined(VFS_BIO_DEBUG) 3825 if (vp->v_auxrefs == 0) 3826 panic("biodone: zero vnode hold count"); 3827 if ((vp->v_flag & VOBJBUF) == 0) 3828 panic("biodone: vnode is not setup for merged cache"); 3829 #endif 3830 3831 foff = bp->b_loffset; 3832 KASSERT(foff != NOOFFSET, ("biodone: no buffer offset")); 3833 KASSERT(obj != NULL, ("biodone: missing VM object")); 3834 3835 #if defined(VFS_BIO_DEBUG) 3836 if (obj->paging_in_progress < bp->b_xio.xio_npages) { 3837 kprintf("biodone: paging in progress(%d) < " 3838 "bp->b_xio.xio_npages(%d)\n", 3839 obj->paging_in_progress, 3840 bp->b_xio.xio_npages); 3841 } 3842 #endif 3843 3844 /* 3845 * Set B_CACHE if the op was a normal read and no error 3846 * occured. B_CACHE is set for writes in the b*write() 3847 * routines. 3848 */ 3849 iosize = bp->b_bcount - bp->b_resid; 3850 if (cmd == BUF_CMD_READ && 3851 (bp->b_flags & (B_INVAL|B_NOCACHE|B_ERROR)) == 0) { 3852 bp->b_flags |= B_CACHE; 3853 } 3854 3855 vm_object_hold(obj); 3856 for (i = 0; i < bp->b_xio.xio_npages; i++) { 3857 int bogusflag = 0; 3858 int resid; 3859 3860 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 3861 if (resid > iosize) 3862 resid = iosize; 3863 3864 /* 3865 * cleanup bogus pages, restoring the originals. Since 3866 * the originals should still be wired, we don't have 3867 * to worry about interrupt/freeing races destroying 3868 * the VM object association. 3869 */ 3870 m = bp->b_xio.xio_pages[i]; 3871 if (m == bogus_page) { 3872 bogusflag = 1; 3873 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3874 if (m == NULL) 3875 panic("biodone: page disappeared"); 3876 bp->b_xio.xio_pages[i] = m; 3877 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3878 bp->b_xio.xio_pages, bp->b_xio.xio_npages); 3879 } 3880 #if defined(VFS_BIO_DEBUG) 3881 if (OFF_TO_IDX(foff) != m->pindex) { 3882 kprintf("biodone: foff(%lu)/m->pindex(%ld) " 3883 "mismatch\n", 3884 (unsigned long)foff, (long)m->pindex); 3885 } 3886 #endif 3887 3888 /* 3889 * In the write case, the valid and clean bits are 3890 * already changed correctly (see bdwrite()), so we 3891 * only need to do this here in the read case. 3892 */ 3893 vm_page_busy_wait(m, FALSE, "bpdpgw"); 3894 if (cmd == BUF_CMD_READ && !bogusflag && resid > 0) { 3895 vfs_clean_one_page(bp, i, m); 3896 } 3897 vm_page_flag_clear(m, PG_ZERO); 3898 3899 /* 3900 * when debugging new filesystems or buffer I/O 3901 * methods, this is the most common error that pops 3902 * up. if you see this, you have not set the page 3903 * busy flag correctly!!! 3904 */ 3905 if (m->busy == 0) { 3906 kprintf("biodone: page busy < 0, " 3907 "pindex: %d, foff: 0x(%x,%x), " 3908 "resid: %d, index: %d\n", 3909 (int) m->pindex, (int)(foff >> 32), 3910 (int) foff & 0xffffffff, resid, i); 3911 if (!vn_isdisk(vp, NULL)) 3912 kprintf(" iosize: %ld, loffset: %lld, " 3913 "flags: 0x%08x, npages: %d\n", 3914 bp->b_vp->v_mount->mnt_stat.f_iosize, 3915 (long long)bp->b_loffset, 3916 bp->b_flags, bp->b_xio.xio_npages); 3917 else 3918 kprintf(" VDEV, loffset: %lld, flags: 0x%08x, npages: %d\n", 3919 (long long)bp->b_loffset, 3920 bp->b_flags, bp->b_xio.xio_npages); 3921 kprintf(" valid: 0x%x, dirty: 0x%x, wired: %d\n", 3922 m->valid, m->dirty, m->wire_count); 3923 panic("biodone: page busy < 0"); 3924 } 3925 vm_page_io_finish(m); 3926 vm_page_wakeup(m); 3927 vm_object_pip_wakeup(obj); 3928 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3929 iosize -= resid; 3930 } 3931 bp->b_flags &= ~B_HASBOGUS; 3932 vm_object_drop(obj); 3933 } 3934 3935 /* 3936 * Finish up by releasing the buffer. There are no more synchronous 3937 * or asynchronous completions, those were handled by bio_done 3938 * callbacks. 3939 */ 3940 if (elseit) { 3941 if (bp->b_flags & (B_NOCACHE|B_INVAL|B_ERROR|B_RELBUF)) 3942 brelse(bp); 3943 else 3944 bqrelse(bp); 3945 } 3946 } 3947 3948 /* 3949 * Normal biodone. 3950 */ 3951 void 3952 biodone(struct bio *bio) 3953 { 3954 struct buf *bp = bio->bio_buf; 3955 3956 runningbufwakeup(bp); 3957 3958 /* 3959 * Run up the chain of BIO's. Leave b_cmd intact for the duration. 3960 */ 3961 while (bio) { 3962 biodone_t *done_func; 3963 struct bio_track *track; 3964 3965 /* 3966 * BIO tracking. Most but not all BIOs are tracked. 3967 */ 3968 if ((track = bio->bio_track) != NULL) { 3969 bio_track_rel(track); 3970 bio->bio_track = NULL; 3971 } 3972 3973 /* 3974 * A bio_done function terminates the loop. The function 3975 * will be responsible for any further chaining and/or 3976 * buffer management. 3977 * 3978 * WARNING! The done function can deallocate the buffer! 3979 */ 3980 if ((done_func = bio->bio_done) != NULL) { 3981 bio->bio_done = NULL; 3982 done_func(bio); 3983 return; 3984 } 3985 bio = bio->bio_prev; 3986 } 3987 3988 /* 3989 * If we've run out of bio's do normal [a]synchronous completion. 3990 */ 3991 bpdone(bp, 1); 3992 } 3993 3994 /* 3995 * Synchronous biodone - this terminates a synchronous BIO. 3996 * 3997 * bpdone() is called with elseit=FALSE, leaving the buffer completed 3998 * but still locked. The caller must brelse() the buffer after waiting 3999 * for completion. 4000 */ 4001 void 4002 biodone_sync(struct bio *bio) 4003 { 4004 struct buf *bp = bio->bio_buf; 4005 int flags; 4006 int nflags; 4007 4008 KKASSERT(bio == &bp->b_bio1); 4009 bpdone(bp, 0); 4010 4011 for (;;) { 4012 flags = bio->bio_flags; 4013 nflags = (flags | BIO_DONE) & ~BIO_WANT; 4014 4015 if (atomic_cmpset_int(&bio->bio_flags, flags, nflags)) { 4016 if (flags & BIO_WANT) 4017 wakeup(bio); 4018 break; 4019 } 4020 } 4021 } 4022 4023 /* 4024 * vfs_unbusy_pages: 4025 * 4026 * This routine is called in lieu of iodone in the case of 4027 * incomplete I/O. This keeps the busy status for pages 4028 * consistant. 4029 */ 4030 void 4031 vfs_unbusy_pages(struct buf *bp) 4032 { 4033 int i; 4034 4035 runningbufwakeup(bp); 4036 4037 if (bp->b_flags & B_VMIO) { 4038 struct vnode *vp = bp->b_vp; 4039 vm_object_t obj; 4040 4041 obj = vp->v_object; 4042 vm_object_hold(obj); 4043 4044 for (i = 0; i < bp->b_xio.xio_npages; i++) { 4045 vm_page_t m = bp->b_xio.xio_pages[i]; 4046 4047 /* 4048 * When restoring bogus changes the original pages 4049 * should still be wired, so we are in no danger of 4050 * losing the object association and do not need 4051 * critical section protection particularly. 4052 */ 4053 if (m == bogus_page) { 4054 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_loffset) + i); 4055 if (!m) { 4056 panic("vfs_unbusy_pages: page missing"); 4057 } 4058 bp->b_xio.xio_pages[i] = m; 4059 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4060 bp->b_xio.xio_pages, bp->b_xio.xio_npages); 4061 } 4062 vm_page_busy_wait(m, FALSE, "bpdpgw"); 4063 vm_page_flag_clear(m, PG_ZERO); 4064 vm_page_io_finish(m); 4065 vm_page_wakeup(m); 4066 vm_object_pip_wakeup(obj); 4067 } 4068 bp->b_flags &= ~B_HASBOGUS; 4069 vm_object_drop(obj); 4070 } 4071 } 4072 4073 /* 4074 * vfs_busy_pages: 4075 * 4076 * This routine is called before a device strategy routine. 4077 * It is used to tell the VM system that paging I/O is in 4078 * progress, and treat the pages associated with the buffer 4079 * almost as being PG_BUSY. Also the object 'paging_in_progress' 4080 * flag is handled to make sure that the object doesn't become 4081 * inconsistant. 4082 * 4083 * Since I/O has not been initiated yet, certain buffer flags 4084 * such as B_ERROR or B_INVAL may be in an inconsistant state 4085 * and should be ignored. 4086 * 4087 * MPSAFE 4088 */ 4089 void 4090 vfs_busy_pages(struct vnode *vp, struct buf *bp) 4091 { 4092 int i, bogus; 4093 struct lwp *lp = curthread->td_lwp; 4094 4095 /* 4096 * The buffer's I/O command must already be set. If reading, 4097 * B_CACHE must be 0 (double check against callers only doing 4098 * I/O when B_CACHE is 0). 4099 */ 4100 KKASSERT(bp->b_cmd != BUF_CMD_DONE); 4101 KKASSERT(bp->b_cmd == BUF_CMD_WRITE || (bp->b_flags & B_CACHE) == 0); 4102 4103 if (bp->b_flags & B_VMIO) { 4104 vm_object_t obj; 4105 4106 obj = vp->v_object; 4107 KASSERT(bp->b_loffset != NOOFFSET, 4108 ("vfs_busy_pages: no buffer offset")); 4109 4110 /* 4111 * Busy all the pages. We have to busy them all at once 4112 * to avoid deadlocks. 4113 */ 4114 retry: 4115 for (i = 0; i < bp->b_xio.xio_npages; i++) { 4116 vm_page_t m = bp->b_xio.xio_pages[i]; 4117 4118 if (vm_page_busy_try(m, FALSE)) { 4119 vm_page_sleep_busy(m, FALSE, "vbpage"); 4120 while (--i >= 0) 4121 vm_page_wakeup(bp->b_xio.xio_pages[i]); 4122 goto retry; 4123 } 4124 } 4125 4126 /* 4127 * Setup for I/O, soft-busy the page right now because 4128 * the next loop may block. 4129 */ 4130 for (i = 0; i < bp->b_xio.xio_npages; i++) { 4131 vm_page_t m = bp->b_xio.xio_pages[i]; 4132 4133 vm_page_flag_clear(m, PG_ZERO); 4134 if ((bp->b_flags & B_CLUSTER) == 0) { 4135 vm_object_pip_add(obj, 1); 4136 vm_page_io_start(m); 4137 } 4138 } 4139 4140 /* 4141 * Adjust protections for I/O and do bogus-page mapping. 4142 * Assume that vm_page_protect() can block (it can block 4143 * if VM_PROT_NONE, don't take any chances regardless). 4144 * 4145 * In particular note that for writes we must incorporate 4146 * page dirtyness from the VM system into the buffer's 4147 * dirty range. 4148 * 4149 * For reads we theoretically must incorporate page dirtyness 4150 * from the VM system to determine if the page needs bogus 4151 * replacement, but we shortcut the test by simply checking 4152 * that all m->valid bits are set, indicating that the page 4153 * is fully valid and does not need to be re-read. For any 4154 * VM system dirtyness the page will also be fully valid 4155 * since it was mapped at one point. 4156 */ 4157 bogus = 0; 4158 for (i = 0; i < bp->b_xio.xio_npages; i++) { 4159 vm_page_t m = bp->b_xio.xio_pages[i]; 4160 4161 vm_page_flag_clear(m, PG_ZERO); /* XXX */ 4162 if (bp->b_cmd == BUF_CMD_WRITE) { 4163 /* 4164 * When readying a vnode-backed buffer for 4165 * a write we must zero-fill any invalid 4166 * portions of the backing VM pages, mark 4167 * it valid and clear related dirty bits. 4168 * 4169 * vfs_clean_one_page() incorporates any 4170 * VM dirtyness and updates the b_dirtyoff 4171 * range (after we've made the page RO). 4172 * 4173 * It is also expected that the pmap modified 4174 * bit has already been cleared by the 4175 * vm_page_protect(). We may not be able 4176 * to clear all dirty bits for a page if it 4177 * was also memory mapped (NFS). 4178 * 4179 * Finally be sure to unassign any swap-cache 4180 * backing store as it is now stale. 4181 */ 4182 vm_page_protect(m, VM_PROT_READ); 4183 vfs_clean_one_page(bp, i, m); 4184 swap_pager_unswapped(m); 4185 } else if (m->valid == VM_PAGE_BITS_ALL) { 4186 /* 4187 * When readying a vnode-backed buffer for 4188 * read we must replace any dirty pages with 4189 * a bogus page so dirty data is not destroyed 4190 * when filling gaps. 4191 * 4192 * To avoid testing whether the page is 4193 * dirty we instead test that the page was 4194 * at some point mapped (m->valid fully 4195 * valid) with the understanding that 4196 * this also covers the dirty case. 4197 */ 4198 bp->b_xio.xio_pages[i] = bogus_page; 4199 bp->b_flags |= B_HASBOGUS; 4200 bogus++; 4201 } else if (m->valid & m->dirty) { 4202 /* 4203 * This case should not occur as partial 4204 * dirtyment can only happen if the buffer 4205 * is B_CACHE, and this code is not entered 4206 * if the buffer is B_CACHE. 4207 */ 4208 kprintf("Warning: vfs_busy_pages - page not " 4209 "fully valid! loff=%jx bpf=%08x " 4210 "idx=%d val=%02x dir=%02x\n", 4211 (intmax_t)bp->b_loffset, bp->b_flags, 4212 i, m->valid, m->dirty); 4213 vm_page_protect(m, VM_PROT_NONE); 4214 } else { 4215 /* 4216 * The page is not valid and can be made 4217 * part of the read. 4218 */ 4219 vm_page_protect(m, VM_PROT_NONE); 4220 } 4221 vm_page_wakeup(m); 4222 } 4223 if (bogus) { 4224 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 4225 bp->b_xio.xio_pages, bp->b_xio.xio_npages); 4226 } 4227 } 4228 4229 /* 4230 * This is the easiest place to put the process accounting for the I/O 4231 * for now. 4232 */ 4233 if (lp != NULL) { 4234 if (bp->b_cmd == BUF_CMD_READ) 4235 lp->lwp_ru.ru_inblock++; 4236 else 4237 lp->lwp_ru.ru_oublock++; 4238 } 4239 } 4240 4241 /* 4242 * Tell the VM system that the pages associated with this buffer 4243 * are clean. This is used for delayed writes where the data is 4244 * going to go to disk eventually without additional VM intevention. 4245 * 4246 * NOTE: While we only really need to clean through to b_bcount, we 4247 * just go ahead and clean through to b_bufsize. 4248 */ 4249 static void 4250 vfs_clean_pages(struct buf *bp) 4251 { 4252 vm_page_t m; 4253 int i; 4254 4255 if ((bp->b_flags & B_VMIO) == 0) 4256 return; 4257 4258 KASSERT(bp->b_loffset != NOOFFSET, 4259 ("vfs_clean_pages: no buffer offset")); 4260 4261 for (i = 0; i < bp->b_xio.xio_npages; i++) { 4262 m = bp->b_xio.xio_pages[i]; 4263 vfs_clean_one_page(bp, i, m); 4264 } 4265 } 4266 4267 /* 4268 * vfs_clean_one_page: 4269 * 4270 * Set the valid bits and clear the dirty bits in a page within a 4271 * buffer. The range is restricted to the buffer's size and the 4272 * buffer's logical offset might index into the first page. 4273 * 4274 * The caller has busied or soft-busied the page and it is not mapped, 4275 * test and incorporate the dirty bits into b_dirtyoff/end before 4276 * clearing them. Note that we need to clear the pmap modified bits 4277 * after determining the the page was dirty, vm_page_set_validclean() 4278 * does not do it for us. 4279 * 4280 * This routine is typically called after a read completes (dirty should 4281 * be zero in that case as we are not called on bogus-replace pages), 4282 * or before a write is initiated. 4283 */ 4284 static void 4285 vfs_clean_one_page(struct buf *bp, int pageno, vm_page_t m) 4286 { 4287 int bcount; 4288 int xoff; 4289 int soff; 4290 int eoff; 4291 4292 /* 4293 * Calculate offset range within the page but relative to buffer's 4294 * loffset. loffset might be offset into the first page. 4295 */ 4296 xoff = (int)bp->b_loffset & PAGE_MASK; /* loffset offset into pg 0 */ 4297 bcount = bp->b_bcount + xoff; /* offset adjusted */ 4298 4299 if (pageno == 0) { 4300 soff = xoff; 4301 eoff = PAGE_SIZE; 4302 } else { 4303 soff = (pageno << PAGE_SHIFT); 4304 eoff = soff + PAGE_SIZE; 4305 } 4306 if (eoff > bcount) 4307 eoff = bcount; 4308 if (soff >= eoff) 4309 return; 4310 4311 /* 4312 * Test dirty bits and adjust b_dirtyoff/end. 4313 * 4314 * If dirty pages are incorporated into the bp any prior 4315 * B_NEEDCOMMIT state (NFS) must be cleared because the 4316 * caller has not taken into account the new dirty data. 4317 * 4318 * If the page was memory mapped the dirty bits might go beyond the 4319 * end of the buffer, but we can't really make the assumption that 4320 * a file EOF straddles the buffer (even though this is the case for 4321 * NFS if B_NEEDCOMMIT is also set). So for the purposes of clearing 4322 * B_NEEDCOMMIT we only test the dirty bits covered by the buffer. 4323 * This also saves some console spam. 4324 * 4325 * When clearing B_NEEDCOMMIT we must also clear B_CLUSTEROK, 4326 * NFS can handle huge commits but not huge writes. 4327 */ 4328 vm_page_test_dirty(m); 4329 if (m->dirty) { 4330 if ((bp->b_flags & B_NEEDCOMMIT) && 4331 (m->dirty & vm_page_bits(soff & PAGE_MASK, eoff - soff))) { 4332 if (debug_commit) 4333 kprintf("Warning: vfs_clean_one_page: bp %p " 4334 "loff=%jx,%d flgs=%08x clr B_NEEDCOMMIT" 4335 " cmd %d vd %02x/%02x x/s/e %d %d %d " 4336 "doff/end %d %d\n", 4337 bp, (intmax_t)bp->b_loffset, bp->b_bcount, 4338 bp->b_flags, bp->b_cmd, 4339 m->valid, m->dirty, xoff, soff, eoff, 4340 bp->b_dirtyoff, bp->b_dirtyend); 4341 bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK); 4342 if (debug_commit) 4343 print_backtrace(-1); 4344 } 4345 /* 4346 * Only clear the pmap modified bits if ALL the dirty bits 4347 * are set, otherwise the system might mis-clear portions 4348 * of a page. 4349 */ 4350 if (m->dirty == VM_PAGE_BITS_ALL && 4351 (bp->b_flags & B_NEEDCOMMIT) == 0) { 4352 pmap_clear_modify(m); 4353 } 4354 if (bp->b_dirtyoff > soff - xoff) 4355 bp->b_dirtyoff = soff - xoff; 4356 if (bp->b_dirtyend < eoff - xoff) 4357 bp->b_dirtyend = eoff - xoff; 4358 } 4359 4360 /* 4361 * Set related valid bits, clear related dirty bits. 4362 * Does not mess with the pmap modified bit. 4363 * 4364 * WARNING! We cannot just clear all of m->dirty here as the 4365 * buffer cache buffers may use a DEV_BSIZE'd aligned 4366 * block size, or have an odd size (e.g. NFS at file EOF). 4367 * The putpages code can clear m->dirty to 0. 4368 * 4369 * If a VOP_WRITE generates a buffer cache buffer which 4370 * covers the same space as mapped writable pages the 4371 * buffer flush might not be able to clear all the dirty 4372 * bits and still require a putpages from the VM system 4373 * to finish it off. 4374 * 4375 * WARNING! vm_page_set_validclean() currently assumes vm_token 4376 * is held. The page might not be busied (bdwrite() case). 4377 * XXX remove this comment once we've validated that this 4378 * is no longer an issue. 4379 */ 4380 vm_page_set_validclean(m, soff & PAGE_MASK, eoff - soff); 4381 } 4382 4383 /* 4384 * Similar to vfs_clean_one_page() but sets the bits to valid and dirty. 4385 * The page data is assumed to be valid (there is no zeroing here). 4386 */ 4387 static void 4388 vfs_dirty_one_page(struct buf *bp, int pageno, vm_page_t m) 4389 { 4390 int bcount; 4391 int xoff; 4392 int soff; 4393 int eoff; 4394 4395 /* 4396 * Calculate offset range within the page but relative to buffer's 4397 * loffset. loffset might be offset into the first page. 4398 */ 4399 xoff = (int)bp->b_loffset & PAGE_MASK; /* loffset offset into pg 0 */ 4400 bcount = bp->b_bcount + xoff; /* offset adjusted */ 4401 4402 if (pageno == 0) { 4403 soff = xoff; 4404 eoff = PAGE_SIZE; 4405 } else { 4406 soff = (pageno << PAGE_SHIFT); 4407 eoff = soff + PAGE_SIZE; 4408 } 4409 if (eoff > bcount) 4410 eoff = bcount; 4411 if (soff >= eoff) 4412 return; 4413 vm_page_set_validdirty(m, soff & PAGE_MASK, eoff - soff); 4414 } 4415 4416 /* 4417 * vfs_bio_clrbuf: 4418 * 4419 * Clear a buffer. This routine essentially fakes an I/O, so we need 4420 * to clear B_ERROR and B_INVAL. 4421 * 4422 * Note that while we only theoretically need to clear through b_bcount, 4423 * we go ahead and clear through b_bufsize. 4424 */ 4425 4426 void 4427 vfs_bio_clrbuf(struct buf *bp) 4428 { 4429 int i, mask = 0; 4430 caddr_t sa, ea; 4431 if ((bp->b_flags & (B_VMIO | B_MALLOC)) == B_VMIO) { 4432 bp->b_flags &= ~(B_INVAL | B_EINTR | B_ERROR); 4433 if ((bp->b_xio.xio_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 4434 (bp->b_loffset & PAGE_MASK) == 0) { 4435 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 4436 if ((bp->b_xio.xio_pages[0]->valid & mask) == mask) { 4437 bp->b_resid = 0; 4438 return; 4439 } 4440 if (((bp->b_xio.xio_pages[0]->flags & PG_ZERO) == 0) && 4441 ((bp->b_xio.xio_pages[0]->valid & mask) == 0)) { 4442 bzero(bp->b_data, bp->b_bufsize); 4443 bp->b_xio.xio_pages[0]->valid |= mask; 4444 bp->b_resid = 0; 4445 return; 4446 } 4447 } 4448 sa = bp->b_data; 4449 for(i=0;i<bp->b_xio.xio_npages;i++,sa=ea) { 4450 int j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; 4451 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); 4452 ea = (caddr_t)(vm_offset_t)ulmin( 4453 (u_long)(vm_offset_t)ea, 4454 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); 4455 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 4456 if ((bp->b_xio.xio_pages[i]->valid & mask) == mask) 4457 continue; 4458 if ((bp->b_xio.xio_pages[i]->valid & mask) == 0) { 4459 if ((bp->b_xio.xio_pages[i]->flags & PG_ZERO) == 0) { 4460 bzero(sa, ea - sa); 4461 } 4462 } else { 4463 for (; sa < ea; sa += DEV_BSIZE, j++) { 4464 if (((bp->b_xio.xio_pages[i]->flags & PG_ZERO) == 0) && 4465 (bp->b_xio.xio_pages[i]->valid & (1<<j)) == 0) 4466 bzero(sa, DEV_BSIZE); 4467 } 4468 } 4469 bp->b_xio.xio_pages[i]->valid |= mask; 4470 vm_page_flag_clear(bp->b_xio.xio_pages[i], PG_ZERO); 4471 } 4472 bp->b_resid = 0; 4473 } else { 4474 clrbuf(bp); 4475 } 4476 } 4477 4478 /* 4479 * vm_hold_load_pages: 4480 * 4481 * Load pages into the buffer's address space. The pages are 4482 * allocated from the kernel object in order to reduce interference 4483 * with the any VM paging I/O activity. The range of loaded 4484 * pages will be wired. 4485 * 4486 * If a page cannot be allocated, the 'pagedaemon' is woken up to 4487 * retrieve the full range (to - from) of pages. 4488 * 4489 * MPSAFE 4490 */ 4491 void 4492 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4493 { 4494 vm_offset_t pg; 4495 vm_page_t p; 4496 int index; 4497 4498 to = round_page(to); 4499 from = round_page(from); 4500 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4501 4502 pg = from; 4503 while (pg < to) { 4504 /* 4505 * Note: must allocate system pages since blocking here 4506 * could intefere with paging I/O, no matter which 4507 * process we are. 4508 */ 4509 vm_object_hold(&kernel_object); 4510 p = bio_page_alloc(&kernel_object, pg >> PAGE_SHIFT, 4511 (vm_pindex_t)((to - pg) >> PAGE_SHIFT)); 4512 vm_object_drop(&kernel_object); 4513 if (p) { 4514 vm_page_wire(p); 4515 p->valid = VM_PAGE_BITS_ALL; 4516 vm_page_flag_clear(p, PG_ZERO); 4517 pmap_kenter(pg, VM_PAGE_TO_PHYS(p)); 4518 bp->b_xio.xio_pages[index] = p; 4519 vm_page_wakeup(p); 4520 4521 pg += PAGE_SIZE; 4522 ++index; 4523 } 4524 } 4525 bp->b_xio.xio_npages = index; 4526 } 4527 4528 /* 4529 * Allocate pages for a buffer cache buffer. 4530 * 4531 * Under extremely severe memory conditions even allocating out of the 4532 * system reserve can fail. If this occurs we must allocate out of the 4533 * interrupt reserve to avoid a deadlock with the pageout daemon. 4534 * 4535 * The pageout daemon can run (putpages -> VOP_WRITE -> getblk -> allocbuf). 4536 * If the buffer cache's vm_page_alloc() fails a vm_wait() can deadlock 4537 * against the pageout daemon if pages are not freed from other sources. 4538 * 4539 * If NULL is returned the caller is expected to retry (typically check if 4540 * the page already exists on retry before trying to allocate one). 4541 */ 4542 static 4543 vm_page_t 4544 bio_page_alloc(vm_object_t obj, vm_pindex_t pg, int deficit) 4545 { 4546 vm_page_t p; 4547 4548 ASSERT_LWKT_TOKEN_HELD(vm_object_token(obj)); 4549 4550 /* 4551 * Try a normal allocation, allow use of system reserve. 4552 */ 4553 p = vm_page_alloc(obj, pg, VM_ALLOC_NORMAL | VM_ALLOC_SYSTEM | 4554 VM_ALLOC_NULL_OK); 4555 if (p) 4556 return(p); 4557 4558 /* 4559 * The normal allocation failed and we clearly have a page 4560 * deficit. Try to reclaim some clean VM pages directly 4561 * from the buffer cache. 4562 */ 4563 vm_pageout_deficit += deficit; 4564 recoverbufpages(); 4565 4566 /* 4567 * We may have blocked, the caller will know what to do if the 4568 * page now exists. 4569 */ 4570 if (vm_page_lookup(obj, pg)) { 4571 return(NULL); 4572 } 4573 4574 /* 4575 * Only system threads can use the interrupt reserve 4576 */ 4577 if ((curthread->td_flags & TDF_SYSTHREAD) == 0) { 4578 vm_wait(hz); 4579 return(NULL); 4580 } 4581 4582 4583 /* 4584 * Allocate and allow use of the interrupt reserve. 4585 * 4586 * If after all that we still can't allocate a VM page we are 4587 * in real trouble, but we slog on anyway hoping that the system 4588 * won't deadlock. 4589 */ 4590 p = vm_page_alloc(obj, pg, VM_ALLOC_NORMAL | VM_ALLOC_SYSTEM | 4591 VM_ALLOC_INTERRUPT | VM_ALLOC_NULL_OK); 4592 if (p) { 4593 if (vm_page_count_severe()) { 4594 ++lowmempgallocs; 4595 vm_wait(hz / 20 + 1); 4596 } 4597 } else if (vm_page_lookup(obj, pg) == NULL) { 4598 kprintf("bio_page_alloc: Memory exhausted during bufcache " 4599 "page allocation\n"); 4600 ++lowmempgfails; 4601 vm_wait(hz); 4602 } 4603 return(p); 4604 } 4605 4606 /* 4607 * vm_hold_free_pages: 4608 * 4609 * Return pages associated with the buffer back to the VM system. 4610 * 4611 * The range of pages underlying the buffer's address space will 4612 * be unmapped and un-wired. 4613 * 4614 * MPSAFE 4615 */ 4616 void 4617 vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 4618 { 4619 vm_offset_t pg; 4620 vm_page_t p; 4621 int index, newnpages; 4622 4623 from = round_page(from); 4624 to = round_page(to); 4625 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 4626 newnpages = index; 4627 4628 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 4629 p = bp->b_xio.xio_pages[index]; 4630 if (p && (index < bp->b_xio.xio_npages)) { 4631 if (p->busy) { 4632 kprintf("vm_hold_free_pages: doffset: %lld, " 4633 "loffset: %lld\n", 4634 (long long)bp->b_bio2.bio_offset, 4635 (long long)bp->b_loffset); 4636 } 4637 bp->b_xio.xio_pages[index] = NULL; 4638 pmap_kremove(pg); 4639 vm_page_busy_wait(p, FALSE, "vmhldpg"); 4640 vm_page_unwire(p, 0); 4641 vm_page_free(p); 4642 } 4643 } 4644 bp->b_xio.xio_npages = newnpages; 4645 } 4646 4647 /* 4648 * vmapbuf: 4649 * 4650 * Map a user buffer into KVM via a pbuf. On return the buffer's 4651 * b_data, b_bufsize, and b_bcount will be set, and its XIO page array 4652 * initialized. 4653 */ 4654 int 4655 vmapbuf(struct buf *bp, caddr_t udata, int bytes) 4656 { 4657 caddr_t addr; 4658 vm_offset_t va; 4659 vm_page_t m; 4660 int vmprot; 4661 int error; 4662 int pidx; 4663 int i; 4664 4665 /* 4666 * bp had better have a command and it better be a pbuf. 4667 */ 4668 KKASSERT(bp->b_cmd != BUF_CMD_DONE); 4669 KKASSERT(bp->b_flags & B_PAGING); 4670 KKASSERT(bp->b_kvabase); 4671 4672 if (bytes < 0) 4673 return (-1); 4674 4675 /* 4676 * Map the user data into KVM. Mappings have to be page-aligned. 4677 */ 4678 addr = (caddr_t)trunc_page((vm_offset_t)udata); 4679 pidx = 0; 4680 4681 vmprot = VM_PROT_READ; 4682 if (bp->b_cmd == BUF_CMD_READ) 4683 vmprot |= VM_PROT_WRITE; 4684 4685 while (addr < udata + bytes) { 4686 /* 4687 * Do the vm_fault if needed; do the copy-on-write thing 4688 * when reading stuff off device into memory. 4689 * 4690 * vm_fault_page*() returns a held VM page. 4691 */ 4692 va = (addr >= udata) ? (vm_offset_t)addr : (vm_offset_t)udata; 4693 va = trunc_page(va); 4694 4695 m = vm_fault_page_quick(va, vmprot, &error); 4696 if (m == NULL) { 4697 for (i = 0; i < pidx; ++i) { 4698 vm_page_unhold(bp->b_xio.xio_pages[i]); 4699 bp->b_xio.xio_pages[i] = NULL; 4700 } 4701 return(-1); 4702 } 4703 bp->b_xio.xio_pages[pidx] = m; 4704 addr += PAGE_SIZE; 4705 ++pidx; 4706 } 4707 4708 /* 4709 * Map the page array and set the buffer fields to point to 4710 * the mapped data buffer. 4711 */ 4712 if (pidx > btoc(MAXPHYS)) 4713 panic("vmapbuf: mapped more than MAXPHYS"); 4714 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_xio.xio_pages, pidx); 4715 4716 bp->b_xio.xio_npages = pidx; 4717 bp->b_data = bp->b_kvabase + ((int)(intptr_t)udata & PAGE_MASK); 4718 bp->b_bcount = bytes; 4719 bp->b_bufsize = bytes; 4720 return(0); 4721 } 4722 4723 /* 4724 * vunmapbuf: 4725 * 4726 * Free the io map PTEs associated with this IO operation. 4727 * We also invalidate the TLB entries and restore the original b_addr. 4728 */ 4729 void 4730 vunmapbuf(struct buf *bp) 4731 { 4732 int pidx; 4733 int npages; 4734 4735 KKASSERT(bp->b_flags & B_PAGING); 4736 4737 npages = bp->b_xio.xio_npages; 4738 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 4739 for (pidx = 0; pidx < npages; ++pidx) { 4740 vm_page_unhold(bp->b_xio.xio_pages[pidx]); 4741 bp->b_xio.xio_pages[pidx] = NULL; 4742 } 4743 bp->b_xio.xio_npages = 0; 4744 bp->b_data = bp->b_kvabase; 4745 } 4746 4747 /* 4748 * Scan all buffers in the system and issue the callback. 4749 */ 4750 int 4751 scan_all_buffers(int (*callback)(struct buf *, void *), void *info) 4752 { 4753 int count = 0; 4754 int error; 4755 int n; 4756 4757 for (n = 0; n < nbuf; ++n) { 4758 if ((error = callback(&buf[n], info)) < 0) { 4759 count = error; 4760 break; 4761 } 4762 count += error; 4763 } 4764 return (count); 4765 } 4766 4767 /* 4768 * nestiobuf_iodone: biodone callback for nested buffers and propagate 4769 * completion to the master buffer. 4770 */ 4771 static void 4772 nestiobuf_iodone(struct bio *bio) 4773 { 4774 struct bio *mbio; 4775 struct buf *mbp, *bp; 4776 struct devstat *stats; 4777 int error; 4778 int donebytes; 4779 4780 bp = bio->bio_buf; 4781 mbio = bio->bio_caller_info1.ptr; 4782 stats = bio->bio_caller_info2.ptr; 4783 mbp = mbio->bio_buf; 4784 4785 KKASSERT(bp->b_bcount <= bp->b_bufsize); 4786 KKASSERT(mbp != bp); 4787 4788 error = bp->b_error; 4789 if (bp->b_error == 0 && 4790 (bp->b_bcount < bp->b_bufsize || bp->b_resid > 0)) { 4791 /* 4792 * Not all got transfered, raise an error. We have no way to 4793 * propagate these conditions to mbp. 4794 */ 4795 error = EIO; 4796 } 4797 4798 donebytes = bp->b_bufsize; 4799 4800 relpbuf(bp, NULL); 4801 4802 nestiobuf_done(mbio, donebytes, error, stats); 4803 } 4804 4805 void 4806 nestiobuf_done(struct bio *mbio, int donebytes, int error, struct devstat *stats) 4807 { 4808 struct buf *mbp; 4809 4810 mbp = mbio->bio_buf; 4811 4812 KKASSERT((int)(intptr_t)mbio->bio_driver_info > 0); 4813 4814 /* 4815 * If an error occured, propagate it to the master buffer. 4816 * 4817 * Several biodone()s may wind up running concurrently so 4818 * use an atomic op to adjust b_flags. 4819 */ 4820 if (error) { 4821 mbp->b_error = error; 4822 atomic_set_int(&mbp->b_flags, B_ERROR); 4823 } 4824 4825 /* 4826 * Decrement the operations in progress counter and terminate the 4827 * I/O if this was the last bit. 4828 */ 4829 if (atomic_fetchadd_int((int *)&mbio->bio_driver_info, -1) == 1) { 4830 mbp->b_resid = 0; 4831 if (stats) 4832 devstat_end_transaction_buf(stats, mbp); 4833 biodone(mbio); 4834 } 4835 } 4836 4837 /* 4838 * Initialize a nestiobuf for use. Set an initial count of 1 to prevent 4839 * the mbio from being biodone()'d while we are still adding sub-bios to 4840 * it. 4841 */ 4842 void 4843 nestiobuf_init(struct bio *bio) 4844 { 4845 bio->bio_driver_info = (void *)1; 4846 } 4847 4848 /* 4849 * The BIOs added to the nestedio have already been started, remove the 4850 * count that placeheld our mbio and biodone() it if the count would 4851 * transition to 0. 4852 */ 4853 void 4854 nestiobuf_start(struct bio *mbio) 4855 { 4856 struct buf *mbp = mbio->bio_buf; 4857 4858 /* 4859 * Decrement the operations in progress counter and terminate the 4860 * I/O if this was the last bit. 4861 */ 4862 if (atomic_fetchadd_int((int *)&mbio->bio_driver_info, -1) == 1) { 4863 if (mbp->b_flags & B_ERROR) 4864 mbp->b_resid = mbp->b_bcount; 4865 else 4866 mbp->b_resid = 0; 4867 biodone(mbio); 4868 } 4869 } 4870 4871 /* 4872 * Set an intermediate error prior to calling nestiobuf_start() 4873 */ 4874 void 4875 nestiobuf_error(struct bio *mbio, int error) 4876 { 4877 struct buf *mbp = mbio->bio_buf; 4878 4879 if (error) { 4880 mbp->b_error = error; 4881 atomic_set_int(&mbp->b_flags, B_ERROR); 4882 } 4883 } 4884 4885 /* 4886 * nestiobuf_add: setup a "nested" buffer. 4887 * 4888 * => 'mbp' is a "master" buffer which is being divided into sub pieces. 4889 * => 'bp' should be a buffer allocated by getiobuf. 4890 * => 'offset' is a byte offset in the master buffer. 4891 * => 'size' is a size in bytes of this nested buffer. 4892 */ 4893 void 4894 nestiobuf_add(struct bio *mbio, struct buf *bp, int offset, size_t size, struct devstat *stats) 4895 { 4896 struct buf *mbp = mbio->bio_buf; 4897 struct vnode *vp = mbp->b_vp; 4898 4899 KKASSERT(mbp->b_bcount >= offset + size); 4900 4901 atomic_add_int((int *)&mbio->bio_driver_info, 1); 4902 4903 /* kernel needs to own the lock for it to be released in biodone */ 4904 BUF_KERNPROC(bp); 4905 bp->b_vp = vp; 4906 bp->b_cmd = mbp->b_cmd; 4907 bp->b_bio1.bio_done = nestiobuf_iodone; 4908 bp->b_data = (char *)mbp->b_data + offset; 4909 bp->b_resid = bp->b_bcount = size; 4910 bp->b_bufsize = bp->b_bcount; 4911 4912 bp->b_bio1.bio_track = NULL; 4913 bp->b_bio1.bio_caller_info1.ptr = mbio; 4914 bp->b_bio1.bio_caller_info2.ptr = stats; 4915 } 4916 4917 /* 4918 * print out statistics from the current status of the buffer pool 4919 * this can be toggeled by the system control option debug.syncprt 4920 */ 4921 #ifdef DEBUG 4922 void 4923 vfs_bufstats(void) 4924 { 4925 int i, j, count; 4926 struct buf *bp; 4927 struct bqueues *dp; 4928 int counts[(MAXBSIZE / PAGE_SIZE) + 1]; 4929 static char *bname[3] = { "LOCKED", "LRU", "AGE" }; 4930 4931 for (dp = bufqueues, i = 0; dp < &bufqueues[3]; dp++, i++) { 4932 count = 0; 4933 for (j = 0; j <= MAXBSIZE/PAGE_SIZE; j++) 4934 counts[j] = 0; 4935 4936 spin_lock(&bufqspin); 4937 TAILQ_FOREACH(bp, dp, b_freelist) { 4938 counts[bp->b_bufsize/PAGE_SIZE]++; 4939 count++; 4940 } 4941 spin_unlock(&bufqspin); 4942 4943 kprintf("%s: total-%d", bname[i], count); 4944 for (j = 0; j <= MAXBSIZE/PAGE_SIZE; j++) 4945 if (counts[j] != 0) 4946 kprintf(", %d-%d", j * PAGE_SIZE, counts[j]); 4947 kprintf("\n"); 4948 } 4949 } 4950 #endif 4951 4952 #ifdef DDB 4953 4954 DB_SHOW_COMMAND(buffer, db_show_buffer) 4955 { 4956 /* get args */ 4957 struct buf *bp = (struct buf *)addr; 4958 4959 if (!have_addr) { 4960 db_printf("usage: show buffer <addr>\n"); 4961 return; 4962 } 4963 4964 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS); 4965 db_printf("b_cmd = %d\n", bp->b_cmd); 4966 db_printf("b_error = %d, b_bufsize = %d, b_bcount = %d, " 4967 "b_resid = %d\n, b_data = %p, " 4968 "bio_offset(disk) = %lld, bio_offset(phys) = %lld\n", 4969 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 4970 bp->b_data, 4971 (long long)bp->b_bio2.bio_offset, 4972 (long long)(bp->b_bio2.bio_next ? 4973 bp->b_bio2.bio_next->bio_offset : (off_t)-1)); 4974 if (bp->b_xio.xio_npages) { 4975 int i; 4976 db_printf("b_xio.xio_npages = %d, pages(OBJ, IDX, PA): ", 4977 bp->b_xio.xio_npages); 4978 for (i = 0; i < bp->b_xio.xio_npages; i++) { 4979 vm_page_t m; 4980 m = bp->b_xio.xio_pages[i]; 4981 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 4982 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 4983 if ((i + 1) < bp->b_xio.xio_npages) 4984 db_printf(","); 4985 } 4986 db_printf("\n"); 4987 } 4988 } 4989 #endif /* DDB */ 4990