1 /* 2 * Copyright (c) 1994,1997 John S. Dyson 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice immediately at the beginning of the file, without modification, 10 * this list of conditions, and the following disclaimer. 11 * 2. Absolutely no warranty of function or purpose is made by the author 12 * John S. Dyson. 13 * 14 * $FreeBSD: src/sys/kern/vfs_bio.c,v 1.242.2.20 2003/05/28 18:38:10 alc Exp $ 15 * $DragonFly: src/sys/kern/vfs_bio.c,v 1.95 2007/11/07 00:46:36 dillon Exp $ 16 */ 17 18 /* 19 * this file contains a new buffer I/O scheme implementing a coherent 20 * VM object and buffer cache scheme. Pains have been taken to make 21 * sure that the performance degradation associated with schemes such 22 * as this is not realized. 23 * 24 * Author: John S. Dyson 25 * Significant help during the development and debugging phases 26 * had been provided by David Greenman, also of the FreeBSD core team. 27 * 28 * see man buf(9) for more info. 29 */ 30 31 #include <sys/param.h> 32 #include <sys/systm.h> 33 #include <sys/buf.h> 34 #include <sys/conf.h> 35 #include <sys/eventhandler.h> 36 #include <sys/lock.h> 37 #include <sys/malloc.h> 38 #include <sys/mount.h> 39 #include <sys/kernel.h> 40 #include <sys/kthread.h> 41 #include <sys/proc.h> 42 #include <sys/reboot.h> 43 #include <sys/resourcevar.h> 44 #include <sys/sysctl.h> 45 #include <sys/vmmeter.h> 46 #include <sys/vnode.h> 47 #include <sys/proc.h> 48 #include <vm/vm.h> 49 #include <vm/vm_param.h> 50 #include <vm/vm_kern.h> 51 #include <vm/vm_pageout.h> 52 #include <vm/vm_page.h> 53 #include <vm/vm_object.h> 54 #include <vm/vm_extern.h> 55 #include <vm/vm_map.h> 56 57 #include <sys/buf2.h> 58 #include <sys/thread2.h> 59 #include <sys/spinlock2.h> 60 #include <vm/vm_page2.h> 61 62 #include "opt_ddb.h" 63 #ifdef DDB 64 #include <ddb/ddb.h> 65 #endif 66 67 /* 68 * Buffer queues. 69 */ 70 #define BUFFER_QUEUES 6 71 enum bufq_type { 72 BQUEUE_NONE, /* not on any queue */ 73 BQUEUE_LOCKED, /* locked buffers */ 74 BQUEUE_CLEAN, /* non-B_DELWRI buffers */ 75 BQUEUE_DIRTY, /* B_DELWRI buffers */ 76 BQUEUE_EMPTYKVA, /* empty buffer headers with KVA assignment */ 77 BQUEUE_EMPTY /* empty buffer headers */ 78 }; 79 TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES]; 80 81 static MALLOC_DEFINE(M_BIOBUF, "BIO buffer", "BIO buffer"); 82 83 struct buf *buf; /* buffer header pool */ 84 85 static void vm_hold_free_pages(struct buf *bp, vm_offset_t from, 86 vm_offset_t to); 87 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from, 88 vm_offset_t to); 89 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, 90 int pageno, vm_page_t m); 91 static void vfs_clean_pages(struct buf *bp); 92 static void vfs_setdirty(struct buf *bp); 93 static void vfs_vmio_release(struct buf *bp); 94 static int flushbufqueues(void); 95 96 static void buf_daemon (void); 97 /* 98 * bogus page -- for I/O to/from partially complete buffers 99 * this is a temporary solution to the problem, but it is not 100 * really that bad. it would be better to split the buffer 101 * for input in the case of buffers partially already in memory, 102 * but the code is intricate enough already. 103 */ 104 vm_page_t bogus_page; 105 int runningbufspace; 106 107 /* 108 * These are all static, but make the ones we export globals so we do 109 * not need to use compiler magic. 110 */ 111 int bufspace, maxbufspace, 112 bufmallocspace, maxbufmallocspace, lobufspace, hibufspace; 113 static int bufreusecnt, bufdefragcnt, buffreekvacnt; 114 static int lorunningspace, hirunningspace, runningbufreq; 115 int numdirtybuffers, lodirtybuffers, hidirtybuffers; 116 static int numfreebuffers, lofreebuffers, hifreebuffers; 117 static int getnewbufcalls; 118 static int getnewbufrestarts; 119 120 static int needsbuffer; /* locked by needsbuffer_spin */ 121 static int bd_request; /* locked by needsbuffer_spin */ 122 static struct spinlock needsbuffer_spin; 123 124 /* 125 * Sysctls for operational control of the buffer cache. 126 */ 127 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0, 128 "Number of dirty buffers to flush before bufdaemon becomes inactive"); 129 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0, 130 "High watermark used to trigger explicit flushing of dirty buffers"); 131 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0, 132 "Low watermark for special reserve in low-memory situations"); 133 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0, 134 "High watermark for special reserve in low-memory situations"); 135 SYSCTL_INT(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0, 136 "Minimum amount of buffer space required for active I/O"); 137 SYSCTL_INT(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0, 138 "Maximum amount of buffer space to usable for active I/O"); 139 /* 140 * Sysctls determining current state of the buffer cache. 141 */ 142 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0, 143 "Pending number of dirty buffers"); 144 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, 145 "Number of free buffers on the buffer cache free list"); 146 SYSCTL_INT(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 147 "I/O bytes currently in progress due to asynchronous writes"); 148 SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0, 149 "Hard limit on maximum amount of memory usable for buffer space"); 150 SYSCTL_INT(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0, 151 "Soft limit on maximum amount of memory usable for buffer space"); 152 SYSCTL_INT(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0, 153 "Minimum amount of memory to reserve for system buffer space"); 154 SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, 155 "Amount of memory available for buffers"); 156 SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RD, &maxbufmallocspace, 157 0, "Maximum amount of memory reserved for buffers using malloc"); 158 SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 159 "Amount of memory left for buffers using malloc-scheme"); 160 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RD, &getnewbufcalls, 0, 161 "New buffer header acquisition requests"); 162 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RD, &getnewbufrestarts, 163 0, "New buffer header acquisition restarts"); 164 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RD, &bufdefragcnt, 0, 165 "Buffer acquisition restarts due to fragmented buffer map"); 166 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RD, &buffreekvacnt, 0, 167 "Amount of time KVA space was deallocated in an arbitrary buffer"); 168 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RD, &bufreusecnt, 0, 169 "Amount of time buffer re-use operations were successful"); 170 SYSCTL_INT(_debug_sizeof, OID_AUTO, buf, CTLFLAG_RD, 0, sizeof(struct buf), 171 "sizeof(struct buf)"); 172 173 char *buf_wmesg = BUF_WMESG; 174 175 extern int vm_swap_size; 176 177 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 178 #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */ 179 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ 180 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 181 182 /* 183 * numdirtywakeup: 184 * 185 * If someone is blocked due to there being too many dirty buffers, 186 * and numdirtybuffers is now reasonable, wake them up. 187 */ 188 189 static __inline void 190 numdirtywakeup(int level) 191 { 192 if (numdirtybuffers <= level) { 193 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) { 194 spin_lock_wr(&needsbuffer_spin); 195 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH; 196 spin_unlock_wr(&needsbuffer_spin); 197 wakeup(&needsbuffer); 198 } 199 } 200 } 201 202 /* 203 * bufspacewakeup: 204 * 205 * Called when buffer space is potentially available for recovery. 206 * getnewbuf() will block on this flag when it is unable to free 207 * sufficient buffer space. Buffer space becomes recoverable when 208 * bp's get placed back in the queues. 209 */ 210 211 static __inline void 212 bufspacewakeup(void) 213 { 214 /* 215 * If someone is waiting for BUF space, wake them up. Even 216 * though we haven't freed the kva space yet, the waiting 217 * process will be able to now. 218 */ 219 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) { 220 spin_lock_wr(&needsbuffer_spin); 221 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE; 222 spin_unlock_wr(&needsbuffer_spin); 223 wakeup(&needsbuffer); 224 } 225 } 226 227 /* 228 * runningbufwakeup: 229 * 230 * Accounting for I/O in progress. 231 * 232 */ 233 static __inline void 234 runningbufwakeup(struct buf *bp) 235 { 236 if (bp->b_runningbufspace) { 237 runningbufspace -= bp->b_runningbufspace; 238 bp->b_runningbufspace = 0; 239 if (runningbufreq && runningbufspace <= lorunningspace) { 240 runningbufreq = 0; 241 wakeup(&runningbufreq); 242 } 243 } 244 } 245 246 /* 247 * bufcountwakeup: 248 * 249 * Called when a buffer has been added to one of the free queues to 250 * account for the buffer and to wakeup anyone waiting for free buffers. 251 * This typically occurs when large amounts of metadata are being handled 252 * by the buffer cache ( else buffer space runs out first, usually ). 253 */ 254 255 static __inline void 256 bufcountwakeup(void) 257 { 258 ++numfreebuffers; 259 if (needsbuffer) { 260 spin_lock_wr(&needsbuffer_spin); 261 needsbuffer &= ~VFS_BIO_NEED_ANY; 262 if (numfreebuffers >= hifreebuffers) 263 needsbuffer &= ~VFS_BIO_NEED_FREE; 264 spin_unlock_wr(&needsbuffer_spin); 265 wakeup(&needsbuffer); 266 } 267 } 268 269 /* 270 * waitrunningbufspace() 271 * 272 * runningbufspace is a measure of the amount of I/O currently 273 * running. This routine is used in async-write situations to 274 * prevent creating huge backups of pending writes to a device. 275 * Only asynchronous writes are governed by this function. 276 * 277 * Reads will adjust runningbufspace, but will not block based on it. 278 * The read load has a side effect of reducing the allowed write load. 279 * 280 * This does NOT turn an async write into a sync write. It waits 281 * for earlier writes to complete and generally returns before the 282 * caller's write has reached the device. 283 */ 284 static __inline void 285 waitrunningbufspace(void) 286 { 287 if (runningbufspace > hirunningspace) { 288 crit_enter(); 289 while (runningbufspace > hirunningspace) { 290 ++runningbufreq; 291 tsleep(&runningbufreq, 0, "wdrain", 0); 292 } 293 crit_exit(); 294 } 295 } 296 297 /* 298 * vfs_buf_test_cache: 299 * 300 * Called when a buffer is extended. This function clears the B_CACHE 301 * bit if the newly extended portion of the buffer does not contain 302 * valid data. 303 */ 304 static __inline__ 305 void 306 vfs_buf_test_cache(struct buf *bp, 307 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 308 vm_page_t m) 309 { 310 if (bp->b_flags & B_CACHE) { 311 int base = (foff + off) & PAGE_MASK; 312 if (vm_page_is_valid(m, base, size) == 0) 313 bp->b_flags &= ~B_CACHE; 314 } 315 } 316 317 /* 318 * bd_wakeup: 319 * 320 * Wake up the buffer daemon if the number of outstanding dirty buffers 321 * is above specified threshold 'dirtybuflevel'. 322 * 323 * The buffer daemon is explicitly woken up when (a) the pending number 324 * of dirty buffers exceeds the recovery and stall mid-point value, 325 * (b) during bwillwrite() or (c) buf freelist was exhausted. 326 */ 327 static __inline__ 328 void 329 bd_wakeup(int dirtybuflevel) 330 { 331 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) { 332 spin_lock_wr(&needsbuffer_spin); 333 bd_request = 1; 334 spin_unlock_wr(&needsbuffer_spin); 335 wakeup(&bd_request); 336 } 337 } 338 339 /* 340 * bd_speedup: 341 * 342 * Speed up the buffer cache flushing process. 343 */ 344 345 static __inline__ 346 void 347 bd_speedup(void) 348 { 349 bd_wakeup(1); 350 } 351 352 /* 353 * bufinit: 354 * 355 * Load time initialisation of the buffer cache, called from machine 356 * dependant initialization code. 357 */ 358 void 359 bufinit(void) 360 { 361 struct buf *bp; 362 vm_offset_t bogus_offset; 363 int i; 364 365 spin_init(&needsbuffer_spin); 366 367 /* next, make a null set of free lists */ 368 for (i = 0; i < BUFFER_QUEUES; i++) 369 TAILQ_INIT(&bufqueues[i]); 370 371 /* finally, initialize each buffer header and stick on empty q */ 372 for (i = 0; i < nbuf; i++) { 373 bp = &buf[i]; 374 bzero(bp, sizeof *bp); 375 bp->b_flags = B_INVAL; /* we're just an empty header */ 376 bp->b_cmd = BUF_CMD_DONE; 377 bp->b_qindex = BQUEUE_EMPTY; 378 initbufbio(bp); 379 xio_init(&bp->b_xio); 380 buf_dep_init(bp); 381 BUF_LOCKINIT(bp); 382 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_EMPTY], bp, b_freelist); 383 } 384 385 /* 386 * maxbufspace is the absolute maximum amount of buffer space we are 387 * allowed to reserve in KVM and in real terms. The absolute maximum 388 * is nominally used by buf_daemon. hibufspace is the nominal maximum 389 * used by most other processes. The differential is required to 390 * ensure that buf_daemon is able to run when other processes might 391 * be blocked waiting for buffer space. 392 * 393 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 394 * this may result in KVM fragmentation which is not handled optimally 395 * by the system. 396 */ 397 maxbufspace = nbuf * BKVASIZE; 398 hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 399 lobufspace = hibufspace - MAXBSIZE; 400 401 lorunningspace = 512 * 1024; 402 hirunningspace = 1024 * 1024; 403 404 /* 405 * Limit the amount of malloc memory since it is wired permanently into 406 * the kernel space. Even though this is accounted for in the buffer 407 * allocation, we don't want the malloced region to grow uncontrolled. 408 * The malloc scheme improves memory utilization significantly on average 409 * (small) directories. 410 */ 411 maxbufmallocspace = hibufspace / 20; 412 413 /* 414 * Reduce the chance of a deadlock occuring by limiting the number 415 * of delayed-write dirty buffers we allow to stack up. 416 */ 417 hidirtybuffers = nbuf / 4 + 20; 418 numdirtybuffers = 0; 419 /* 420 * To support extreme low-memory systems, make sure hidirtybuffers cannot 421 * eat up all available buffer space. This occurs when our minimum cannot 422 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 423 * BKVASIZE'd (8K) buffers. 424 */ 425 while (hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 426 hidirtybuffers >>= 1; 427 } 428 lodirtybuffers = hidirtybuffers / 2; 429 430 /* 431 * Try to keep the number of free buffers in the specified range, 432 * and give special processes (e.g. like buf_daemon) access to an 433 * emergency reserve. 434 */ 435 lofreebuffers = nbuf / 18 + 5; 436 hifreebuffers = 2 * lofreebuffers; 437 numfreebuffers = nbuf; 438 439 /* 440 * Maximum number of async ops initiated per buf_daemon loop. This is 441 * somewhat of a hack at the moment, we really need to limit ourselves 442 * based on the number of bytes of I/O in-transit that were initiated 443 * from buf_daemon. 444 */ 445 446 bogus_offset = kmem_alloc_pageable(&kernel_map, PAGE_SIZE); 447 bogus_page = vm_page_alloc(&kernel_object, 448 (bogus_offset >> PAGE_SHIFT), 449 VM_ALLOC_NORMAL); 450 vmstats.v_wire_count++; 451 452 } 453 454 /* 455 * Initialize the embedded bio structures 456 */ 457 void 458 initbufbio(struct buf *bp) 459 { 460 bp->b_bio1.bio_buf = bp; 461 bp->b_bio1.bio_prev = NULL; 462 bp->b_bio1.bio_offset = NOOFFSET; 463 bp->b_bio1.bio_next = &bp->b_bio2; 464 bp->b_bio1.bio_done = NULL; 465 466 bp->b_bio2.bio_buf = bp; 467 bp->b_bio2.bio_prev = &bp->b_bio1; 468 bp->b_bio2.bio_offset = NOOFFSET; 469 bp->b_bio2.bio_next = NULL; 470 bp->b_bio2.bio_done = NULL; 471 } 472 473 /* 474 * Reinitialize the embedded bio structures as well as any additional 475 * translation cache layers. 476 */ 477 void 478 reinitbufbio(struct buf *bp) 479 { 480 struct bio *bio; 481 482 for (bio = &bp->b_bio1; bio; bio = bio->bio_next) { 483 bio->bio_done = NULL; 484 bio->bio_offset = NOOFFSET; 485 } 486 } 487 488 /* 489 * Push another BIO layer onto an existing BIO and return it. The new 490 * BIO layer may already exist, holding cached translation data. 491 */ 492 struct bio * 493 push_bio(struct bio *bio) 494 { 495 struct bio *nbio; 496 497 if ((nbio = bio->bio_next) == NULL) { 498 int index = bio - &bio->bio_buf->b_bio_array[0]; 499 if (index >= NBUF_BIO - 1) { 500 panic("push_bio: too many layers bp %p\n", 501 bio->bio_buf); 502 } 503 nbio = &bio->bio_buf->b_bio_array[index + 1]; 504 bio->bio_next = nbio; 505 nbio->bio_prev = bio; 506 nbio->bio_buf = bio->bio_buf; 507 nbio->bio_offset = NOOFFSET; 508 nbio->bio_done = NULL; 509 nbio->bio_next = NULL; 510 } 511 KKASSERT(nbio->bio_done == NULL); 512 return(nbio); 513 } 514 515 void 516 pop_bio(struct bio *bio) 517 { 518 /* NOP */ 519 } 520 521 void 522 clearbiocache(struct bio *bio) 523 { 524 while (bio) { 525 bio->bio_offset = NOOFFSET; 526 bio = bio->bio_next; 527 } 528 } 529 530 /* 531 * bfreekva: 532 * 533 * Free the KVA allocation for buffer 'bp'. 534 * 535 * Must be called from a critical section as this is the only locking for 536 * buffer_map. 537 * 538 * Since this call frees up buffer space, we call bufspacewakeup(). 539 */ 540 static void 541 bfreekva(struct buf *bp) 542 { 543 int count; 544 545 if (bp->b_kvasize) { 546 ++buffreekvacnt; 547 count = vm_map_entry_reserve(MAP_RESERVE_COUNT); 548 vm_map_lock(&buffer_map); 549 bufspace -= bp->b_kvasize; 550 vm_map_delete(&buffer_map, 551 (vm_offset_t) bp->b_kvabase, 552 (vm_offset_t) bp->b_kvabase + bp->b_kvasize, 553 &count 554 ); 555 vm_map_unlock(&buffer_map); 556 vm_map_entry_release(count); 557 bp->b_kvasize = 0; 558 bufspacewakeup(); 559 } 560 } 561 562 /* 563 * bremfree: 564 * 565 * Remove the buffer from the appropriate free list. 566 */ 567 void 568 bremfree(struct buf *bp) 569 { 570 int old_qindex; 571 572 crit_enter(); 573 old_qindex = bp->b_qindex; 574 575 if (bp->b_qindex != BQUEUE_NONE) { 576 KASSERT(BUF_REFCNTNB(bp) == 1, 577 ("bremfree: bp %p not locked",bp)); 578 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 579 bp->b_qindex = BQUEUE_NONE; 580 } else { 581 if (BUF_REFCNTNB(bp) <= 1) 582 panic("bremfree: removing a buffer not on a queue"); 583 } 584 585 /* 586 * Fixup numfreebuffers count. If the buffer is invalid or not 587 * delayed-write, and it was on the EMPTY, LRU, or AGE queues, 588 * the buffer was free and we must decrement numfreebuffers. 589 */ 590 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { 591 switch(old_qindex) { 592 case BQUEUE_DIRTY: 593 case BQUEUE_CLEAN: 594 case BQUEUE_EMPTY: 595 case BQUEUE_EMPTYKVA: 596 --numfreebuffers; 597 break; 598 default: 599 break; 600 } 601 } 602 crit_exit(); 603 } 604 605 606 /* 607 * bread: 608 * 609 * Get a buffer with the specified data. Look in the cache first. We 610 * must clear B_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 611 * is set, the buffer is valid and we do not have to do anything ( see 612 * getblk() ). 613 */ 614 int 615 bread(struct vnode *vp, off_t loffset, int size, struct buf **bpp) 616 { 617 struct buf *bp; 618 619 bp = getblk(vp, loffset, size, 0, 0); 620 *bpp = bp; 621 622 /* if not found in cache, do some I/O */ 623 if ((bp->b_flags & B_CACHE) == 0) { 624 KASSERT(!(bp->b_flags & B_ASYNC), ("bread: illegal async bp %p", bp)); 625 bp->b_flags &= ~(B_ERROR | B_INVAL); 626 bp->b_cmd = BUF_CMD_READ; 627 vfs_busy_pages(vp, bp); 628 vn_strategy(vp, &bp->b_bio1); 629 return (biowait(bp)); 630 } 631 return (0); 632 } 633 634 /* 635 * breadn: 636 * 637 * Operates like bread, but also starts asynchronous I/O on 638 * read-ahead blocks. We must clear B_ERROR and B_INVAL prior 639 * to initiating I/O . If B_CACHE is set, the buffer is valid 640 * and we do not have to do anything. 641 */ 642 int 643 breadn(struct vnode *vp, off_t loffset, int size, off_t *raoffset, 644 int *rabsize, int cnt, struct buf **bpp) 645 { 646 struct buf *bp, *rabp; 647 int i; 648 int rv = 0, readwait = 0; 649 650 *bpp = bp = getblk(vp, loffset, size, 0, 0); 651 652 /* if not found in cache, do some I/O */ 653 if ((bp->b_flags & B_CACHE) == 0) { 654 bp->b_flags &= ~(B_ERROR | B_INVAL); 655 bp->b_cmd = BUF_CMD_READ; 656 vfs_busy_pages(vp, bp); 657 vn_strategy(vp, &bp->b_bio1); 658 ++readwait; 659 } 660 661 for (i = 0; i < cnt; i++, raoffset++, rabsize++) { 662 if (inmem(vp, *raoffset)) 663 continue; 664 rabp = getblk(vp, *raoffset, *rabsize, 0, 0); 665 666 if ((rabp->b_flags & B_CACHE) == 0) { 667 rabp->b_flags |= B_ASYNC; 668 rabp->b_flags &= ~(B_ERROR | B_INVAL); 669 rabp->b_cmd = BUF_CMD_READ; 670 vfs_busy_pages(vp, rabp); 671 BUF_KERNPROC(rabp); 672 vn_strategy(vp, &rabp->b_bio1); 673 } else { 674 brelse(rabp); 675 } 676 } 677 678 if (readwait) { 679 rv = biowait(bp); 680 } 681 return (rv); 682 } 683 684 /* 685 * bwrite: 686 * 687 * Write, release buffer on completion. (Done by iodone 688 * if async). Do not bother writing anything if the buffer 689 * is invalid. 690 * 691 * Note that we set B_CACHE here, indicating that buffer is 692 * fully valid and thus cacheable. This is true even of NFS 693 * now so we set it generally. This could be set either here 694 * or in biodone() since the I/O is synchronous. We put it 695 * here. 696 */ 697 int 698 bwrite(struct buf *bp) 699 { 700 int oldflags; 701 702 if (bp->b_flags & B_INVAL) { 703 brelse(bp); 704 return (0); 705 } 706 707 oldflags = bp->b_flags; 708 709 if (BUF_REFCNTNB(bp) == 0) 710 panic("bwrite: buffer is not busy???"); 711 crit_enter(); 712 713 /* Mark the buffer clean */ 714 bundirty(bp); 715 716 bp->b_flags &= ~B_ERROR; 717 bp->b_flags |= B_CACHE; 718 bp->b_cmd = BUF_CMD_WRITE; 719 vfs_busy_pages(bp->b_vp, bp); 720 721 /* 722 * Normal bwrites pipeline writes. NOTE: b_bufsize is only 723 * valid for vnode-backed buffers. 724 */ 725 bp->b_runningbufspace = bp->b_bufsize; 726 runningbufspace += bp->b_runningbufspace; 727 728 crit_exit(); 729 if (oldflags & B_ASYNC) 730 BUF_KERNPROC(bp); 731 vn_strategy(bp->b_vp, &bp->b_bio1); 732 733 if ((oldflags & B_ASYNC) == 0) { 734 int rtval = biowait(bp); 735 brelse(bp); 736 return (rtval); 737 } else if ((oldflags & B_NOWDRAIN) == 0) { 738 /* 739 * don't allow the async write to saturate the I/O 740 * system. Deadlocks can occur only if a device strategy 741 * routine (like in VN) turns around and issues another 742 * high-level write, in which case B_NOWDRAIN is expected 743 * to be set. Otherwise we will not deadlock here because 744 * we are blocking waiting for I/O that is already in-progress 745 * to complete. 746 */ 747 waitrunningbufspace(); 748 } 749 750 return (0); 751 } 752 753 /* 754 * bdwrite: 755 * 756 * Delayed write. (Buffer is marked dirty). Do not bother writing 757 * anything if the buffer is marked invalid. 758 * 759 * Note that since the buffer must be completely valid, we can safely 760 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 761 * biodone() in order to prevent getblk from writing the buffer 762 * out synchronously. 763 */ 764 void 765 bdwrite(struct buf *bp) 766 { 767 if (BUF_REFCNTNB(bp) == 0) 768 panic("bdwrite: buffer is not busy"); 769 770 if (bp->b_flags & B_INVAL) { 771 brelse(bp); 772 return; 773 } 774 bdirty(bp); 775 776 /* 777 * Set B_CACHE, indicating that the buffer is fully valid. This is 778 * true even of NFS now. 779 */ 780 bp->b_flags |= B_CACHE; 781 782 /* 783 * This bmap keeps the system from needing to do the bmap later, 784 * perhaps when the system is attempting to do a sync. Since it 785 * is likely that the indirect block -- or whatever other datastructure 786 * that the filesystem needs is still in memory now, it is a good 787 * thing to do this. Note also, that if the pageout daemon is 788 * requesting a sync -- there might not be enough memory to do 789 * the bmap then... So, this is important to do. 790 */ 791 if (bp->b_bio2.bio_offset == NOOFFSET) { 792 VOP_BMAP(bp->b_vp, bp->b_loffset, &bp->b_bio2.bio_offset, 793 NULL, NULL); 794 } 795 796 /* 797 * Set the *dirty* buffer range based upon the VM system dirty pages. 798 */ 799 vfs_setdirty(bp); 800 801 /* 802 * We need to do this here to satisfy the vnode_pager and the 803 * pageout daemon, so that it thinks that the pages have been 804 * "cleaned". Note that since the pages are in a delayed write 805 * buffer -- the VFS layer "will" see that the pages get written 806 * out on the next sync, or perhaps the cluster will be completed. 807 */ 808 vfs_clean_pages(bp); 809 bqrelse(bp); 810 811 /* 812 * Wakeup the buffer flushing daemon if we have a lot of dirty 813 * buffers (midpoint between our recovery point and our stall 814 * point). 815 */ 816 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 817 818 /* 819 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 820 * due to the softdep code. 821 */ 822 } 823 824 /* 825 * bdirty: 826 * 827 * Turn buffer into delayed write request by marking it B_DELWRI. 828 * B_RELBUF and B_NOCACHE must be cleared. 829 * 830 * We reassign the buffer to itself to properly update it in the 831 * dirty/clean lists. 832 * 833 * Since the buffer is not on a queue, we do not update the 834 * numfreebuffers count. 835 * 836 * Must be called from a critical section. 837 * The buffer must be on BQUEUE_NONE. 838 */ 839 void 840 bdirty(struct buf *bp) 841 { 842 KASSERT(bp->b_qindex == BQUEUE_NONE, ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 843 if (bp->b_flags & B_NOCACHE) { 844 kprintf("bdirty: clearing B_NOCACHE on buf %p\n", bp); 845 bp->b_flags &= ~B_NOCACHE; 846 } 847 if (bp->b_flags & B_INVAL) { 848 kprintf("bdirty: warning, dirtying invalid buffer %p\n", bp); 849 } 850 bp->b_flags &= ~B_RELBUF; 851 852 if ((bp->b_flags & B_DELWRI) == 0) { 853 bp->b_flags |= B_DELWRI; 854 reassignbuf(bp); 855 ++numdirtybuffers; 856 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 857 } 858 } 859 860 /* 861 * bundirty: 862 * 863 * Clear B_DELWRI for buffer. 864 * 865 * Since the buffer is not on a queue, we do not update the numfreebuffers 866 * count. 867 * 868 * Must be called from a critical section. 869 * 870 * The buffer is typically on BQUEUE_NONE but there is one case in 871 * brelse() that calls this function after placing the buffer on 872 * a different queue. 873 */ 874 875 void 876 bundirty(struct buf *bp) 877 { 878 if (bp->b_flags & B_DELWRI) { 879 bp->b_flags &= ~B_DELWRI; 880 reassignbuf(bp); 881 --numdirtybuffers; 882 numdirtywakeup(lodirtybuffers); 883 } 884 /* 885 * Since it is now being written, we can clear its deferred write flag. 886 */ 887 bp->b_flags &= ~B_DEFERRED; 888 } 889 890 /* 891 * bawrite: 892 * 893 * Asynchronous write. Start output on a buffer, but do not wait for 894 * it to complete. The buffer is released when the output completes. 895 * 896 * bwrite() ( or the VOP routine anyway ) is responsible for handling 897 * B_INVAL buffers. Not us. 898 */ 899 void 900 bawrite(struct buf *bp) 901 { 902 bp->b_flags |= B_ASYNC; 903 bwrite(bp); 904 } 905 906 /* 907 * bowrite: 908 * 909 * Ordered write. Start output on a buffer, and flag it so that the 910 * device will write it in the order it was queued. The buffer is 911 * released when the output completes. bwrite() ( or the VOP routine 912 * anyway ) is responsible for handling B_INVAL buffers. 913 */ 914 int 915 bowrite(struct buf *bp) 916 { 917 bp->b_flags |= B_ORDERED | B_ASYNC; 918 return (bwrite(bp)); 919 } 920 921 /* 922 * bwillwrite: 923 * 924 * Called prior to the locking of any vnodes when we are expecting to 925 * write. We do not want to starve the buffer cache with too many 926 * dirty buffers so we block here. By blocking prior to the locking 927 * of any vnodes we attempt to avoid the situation where a locked vnode 928 * prevents the various system daemons from flushing related buffers. 929 */ 930 931 void 932 bwillwrite(void) 933 { 934 if (numdirtybuffers >= hidirtybuffers) { 935 while (numdirtybuffers >= hidirtybuffers) { 936 bd_wakeup(1); 937 spin_lock_wr(&needsbuffer_spin); 938 if (numdirtybuffers >= hidirtybuffers) { 939 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH; 940 msleep(&needsbuffer, &needsbuffer_spin, 0, 941 "flswai", 0); 942 } 943 spin_unlock_wr(&needsbuffer_spin); 944 } 945 } 946 } 947 948 /* 949 * buf_dirty_count_severe: 950 * 951 * Return true if we have too many dirty buffers. 952 */ 953 int 954 buf_dirty_count_severe(void) 955 { 956 return(numdirtybuffers >= hidirtybuffers); 957 } 958 959 /* 960 * brelse: 961 * 962 * Release a busy buffer and, if requested, free its resources. The 963 * buffer will be stashed in the appropriate bufqueue[] allowing it 964 * to be accessed later as a cache entity or reused for other purposes. 965 */ 966 void 967 brelse(struct buf *bp) 968 { 969 #ifdef INVARIANTS 970 int saved_flags = bp->b_flags; 971 #endif 972 973 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 974 975 crit_enter(); 976 977 /* 978 * If B_NOCACHE is set we are being asked to destroy the buffer and 979 * its backing store. Clear B_DELWRI. 980 * 981 * B_NOCACHE is set in two cases: (1) when the caller really wants 982 * to destroy the buffer and backing store and (2) when the caller 983 * wants to destroy the buffer and backing store after a write 984 * completes. 985 */ 986 if ((bp->b_flags & (B_NOCACHE|B_DELWRI)) == (B_NOCACHE|B_DELWRI)) { 987 bundirty(bp); 988 } 989 990 if (bp->b_flags & B_LOCKED) 991 bp->b_flags &= ~B_ERROR; 992 993 /* 994 * If a write error occurs and the caller does not want to throw 995 * away the buffer, redirty the buffer. This will also clear 996 * B_NOCACHE. 997 */ 998 if (bp->b_cmd == BUF_CMD_WRITE && 999 (bp->b_flags & (B_ERROR | B_INVAL)) == B_ERROR) { 1000 /* 1001 * Failed write, redirty. Must clear B_ERROR to prevent 1002 * pages from being scrapped. If B_INVAL is set then 1003 * this case is not run and the next case is run to 1004 * destroy the buffer. B_INVAL can occur if the buffer 1005 * is outside the range supported by the underlying device. 1006 */ 1007 bp->b_flags &= ~B_ERROR; 1008 bdirty(bp); 1009 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR)) || 1010 (bp->b_bufsize <= 0) || bp->b_cmd == BUF_CMD_FREEBLKS) { 1011 /* 1012 * Either a failed I/O or we were asked to free or not 1013 * cache the buffer. 1014 * 1015 * NOTE: HAMMER will set B_LOCKED in buf_deallocate if the 1016 * buffer cannot be immediately freed. 1017 */ 1018 bp->b_flags |= B_INVAL; 1019 if (LIST_FIRST(&bp->b_dep) != NULL) 1020 buf_deallocate(bp); 1021 if (bp->b_flags & B_DELWRI) { 1022 --numdirtybuffers; 1023 numdirtywakeup(lodirtybuffers); 1024 } 1025 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1026 } 1027 1028 /* 1029 * We must clear B_RELBUF if B_DELWRI or B_LOCKED is set. 1030 * If vfs_vmio_release() is called with either bit set, the 1031 * underlying pages may wind up getting freed causing a previous 1032 * write (bdwrite()) to get 'lost' because pages associated with 1033 * a B_DELWRI bp are marked clean. Pages associated with a 1034 * B_LOCKED buffer may be mapped by the filesystem. 1035 * 1036 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1037 * if B_DELWRI is set. 1038 * 1039 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1040 * on pages to return pages to the VM page queues. 1041 */ 1042 if (bp->b_flags & (B_DELWRI | B_LOCKED)) 1043 bp->b_flags &= ~B_RELBUF; 1044 else if (vm_page_count_severe()) 1045 bp->b_flags |= B_RELBUF; 1046 1047 /* 1048 * At this point destroying the buffer is governed by the B_INVAL 1049 * or B_RELBUF flags. 1050 */ 1051 bp->b_cmd = BUF_CMD_DONE; 1052 1053 /* 1054 * VMIO buffer rundown. Make sure the VM page array is restored 1055 * after an I/O may have replaces some of the pages with bogus pages 1056 * in order to not destroy dirty pages in a fill-in read. 1057 * 1058 * Note that due to the code above, if a buffer is marked B_DELWRI 1059 * then the B_RELBUF and B_NOCACHE bits will always be clear. 1060 * B_INVAL may still be set, however. 1061 * 1062 * For clean buffers, B_INVAL or B_RELBUF will destroy the buffer 1063 * but not the backing store. B_NOCACHE will destroy the backing 1064 * store. 1065 * 1066 * Note that dirty NFS buffers contain byte-granular write ranges 1067 * and should not be destroyed w/ B_INVAL even if the backing store 1068 * is left intact. 1069 */ 1070 if (bp->b_flags & B_VMIO) { 1071 /* 1072 * Rundown for VMIO buffers which are not dirty NFS buffers. 1073 */ 1074 int i, j, resid; 1075 vm_page_t m; 1076 off_t foff; 1077 vm_pindex_t poff; 1078 vm_object_t obj; 1079 struct vnode *vp; 1080 1081 vp = bp->b_vp; 1082 1083 /* 1084 * Get the base offset and length of the buffer. Note that 1085 * in the VMIO case if the buffer block size is not 1086 * page-aligned then b_data pointer may not be page-aligned. 1087 * But our b_xio.xio_pages array *IS* page aligned. 1088 * 1089 * block sizes less then DEV_BSIZE (usually 512) are not 1090 * supported due to the page granularity bits (m->valid, 1091 * m->dirty, etc...). 1092 * 1093 * See man buf(9) for more information 1094 */ 1095 1096 resid = bp->b_bufsize; 1097 foff = bp->b_loffset; 1098 1099 for (i = 0; i < bp->b_xio.xio_npages; i++) { 1100 m = bp->b_xio.xio_pages[i]; 1101 vm_page_flag_clear(m, PG_ZERO); 1102 /* 1103 * If we hit a bogus page, fixup *all* of them 1104 * now. Note that we left these pages wired 1105 * when we removed them so they had better exist, 1106 * and they cannot be ripped out from under us so 1107 * no critical section protection is necessary. 1108 */ 1109 if (m == bogus_page) { 1110 obj = vp->v_object; 1111 poff = OFF_TO_IDX(bp->b_loffset); 1112 1113 for (j = i; j < bp->b_xio.xio_npages; j++) { 1114 vm_page_t mtmp; 1115 1116 mtmp = bp->b_xio.xio_pages[j]; 1117 if (mtmp == bogus_page) { 1118 mtmp = vm_page_lookup(obj, poff + j); 1119 if (!mtmp) { 1120 panic("brelse: page missing"); 1121 } 1122 bp->b_xio.xio_pages[j] = mtmp; 1123 } 1124 } 1125 1126 if ((bp->b_flags & B_INVAL) == 0) { 1127 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 1128 bp->b_xio.xio_pages, bp->b_xio.xio_npages); 1129 } 1130 m = bp->b_xio.xio_pages[i]; 1131 } 1132 1133 /* 1134 * Invalidate the backing store if B_NOCACHE is set 1135 * (e.g. used with vinvalbuf()). If this is NFS 1136 * we impose a requirement that the block size be 1137 * a multiple of PAGE_SIZE and create a temporary 1138 * hack to basically invalidate the whole page. The 1139 * problem is that NFS uses really odd buffer sizes 1140 * especially when tracking piecemeal writes and 1141 * it also vinvalbuf()'s a lot, which would result 1142 * in only partial page validation and invalidation 1143 * here. If the file page is mmap()'d, however, 1144 * all the valid bits get set so after we invalidate 1145 * here we would end up with weird m->valid values 1146 * like 0xfc. nfs_getpages() can't handle this so 1147 * we clear all the valid bits for the NFS case 1148 * instead of just some of them. 1149 * 1150 * The real bug is the VM system having to set m->valid 1151 * to VM_PAGE_BITS_ALL for faulted-in pages, which 1152 * itself is an artifact of the whole 512-byte 1153 * granular mess that exists to support odd block 1154 * sizes and UFS meta-data block sizes (e.g. 6144). 1155 * A complete rewrite is required. 1156 */ 1157 if (bp->b_flags & (B_NOCACHE|B_ERROR)) { 1158 int poffset = foff & PAGE_MASK; 1159 int presid; 1160 1161 presid = PAGE_SIZE - poffset; 1162 if (bp->b_vp->v_tag == VT_NFS && 1163 bp->b_vp->v_type == VREG) { 1164 ; /* entire page */ 1165 } else if (presid > resid) { 1166 presid = resid; 1167 } 1168 KASSERT(presid >= 0, ("brelse: extra page")); 1169 vm_page_set_invalid(m, poffset, presid); 1170 } 1171 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1172 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1173 } 1174 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1175 vfs_vmio_release(bp); 1176 } else { 1177 /* 1178 * Rundown for non-VMIO buffers. 1179 */ 1180 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1181 #if 0 1182 if (bp->b_vp) 1183 kprintf("brelse bp %p %08x/%08x: Warning, caught and fixed brelvp bug\n", bp, saved_flags, bp->b_flags); 1184 #endif 1185 if (bp->b_bufsize) 1186 allocbuf(bp, 0); 1187 if (bp->b_vp) 1188 brelvp(bp); 1189 } 1190 } 1191 1192 if (bp->b_qindex != BQUEUE_NONE) 1193 panic("brelse: free buffer onto another queue???"); 1194 if (BUF_REFCNTNB(bp) > 1) { 1195 /* Temporary panic to verify exclusive locking */ 1196 /* This panic goes away when we allow shared refs */ 1197 panic("brelse: multiple refs"); 1198 /* do not release to free list */ 1199 BUF_UNLOCK(bp); 1200 crit_exit(); 1201 return; 1202 } 1203 1204 /* 1205 * Figure out the correct queue to place the cleaned up buffer on. 1206 * Buffers placed in the EMPTY or EMPTYKVA had better already be 1207 * disassociated from their vnode. 1208 */ 1209 if (bp->b_flags & B_LOCKED) { 1210 /* 1211 * Buffers that are locked are placed in the locked queue 1212 * immediately, regardless of their state. 1213 */ 1214 bp->b_qindex = BQUEUE_LOCKED; 1215 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_LOCKED], bp, b_freelist); 1216 } else if (bp->b_bufsize == 0) { 1217 /* 1218 * Buffers with no memory. Due to conditionals near the top 1219 * of brelse() such buffers should probably already be 1220 * marked B_INVAL and disassociated from their vnode. 1221 */ 1222 bp->b_flags |= B_INVAL; 1223 KASSERT(bp->b_vp == NULL, ("bp1 %p flags %08x/%08x vnode %p unexpectededly still associated!", bp, saved_flags, bp->b_flags, bp->b_vp)); 1224 KKASSERT((bp->b_flags & B_HASHED) == 0); 1225 if (bp->b_kvasize) { 1226 bp->b_qindex = BQUEUE_EMPTYKVA; 1227 } else { 1228 bp->b_qindex = BQUEUE_EMPTY; 1229 } 1230 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1231 } else if (bp->b_flags & (B_ERROR | B_INVAL | B_NOCACHE | B_RELBUF)) { 1232 /* 1233 * Buffers with junk contents. Again these buffers had better 1234 * already be disassociated from their vnode. 1235 */ 1236 KASSERT(bp->b_vp == NULL, ("bp2 %p flags %08x/%08x vnode %p unexpectededly still associated!", bp, saved_flags, bp->b_flags, bp->b_vp)); 1237 KKASSERT((bp->b_flags & B_HASHED) == 0); 1238 bp->b_flags |= B_INVAL; 1239 bp->b_qindex = BQUEUE_CLEAN; 1240 TAILQ_INSERT_HEAD(&bufqueues[BQUEUE_CLEAN], bp, b_freelist); 1241 } else { 1242 /* 1243 * Remaining buffers. These buffers are still associated with 1244 * their vnode. 1245 */ 1246 switch(bp->b_flags & (B_DELWRI|B_AGE)) { 1247 case B_DELWRI | B_AGE: 1248 bp->b_qindex = BQUEUE_DIRTY; 1249 TAILQ_INSERT_HEAD(&bufqueues[BQUEUE_DIRTY], bp, b_freelist); 1250 break; 1251 case B_DELWRI: 1252 bp->b_qindex = BQUEUE_DIRTY; 1253 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_DIRTY], bp, b_freelist); 1254 break; 1255 case B_AGE: 1256 bp->b_qindex = BQUEUE_CLEAN; 1257 TAILQ_INSERT_HEAD(&bufqueues[BQUEUE_CLEAN], bp, b_freelist); 1258 break; 1259 default: 1260 bp->b_qindex = BQUEUE_CLEAN; 1261 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_CLEAN], bp, b_freelist); 1262 break; 1263 } 1264 } 1265 1266 /* 1267 * If B_INVAL, clear B_DELWRI. We've already placed the buffer 1268 * on the correct queue. 1269 */ 1270 if ((bp->b_flags & (B_INVAL|B_DELWRI)) == (B_INVAL|B_DELWRI)) 1271 bundirty(bp); 1272 1273 /* 1274 * Fixup numfreebuffers count. The bp is on an appropriate queue 1275 * unless locked. We then bump numfreebuffers if it is not B_DELWRI. 1276 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1277 * if B_INVAL is set ). 1278 */ 1279 if ((bp->b_flags & (B_LOCKED|B_DELWRI)) == 0) 1280 bufcountwakeup(); 1281 1282 /* 1283 * Something we can maybe free or reuse 1284 */ 1285 if (bp->b_bufsize || bp->b_kvasize) 1286 bufspacewakeup(); 1287 1288 /* 1289 * Clean up temporary flags and unlock the buffer. 1290 */ 1291 bp->b_flags &= ~(B_ORDERED | B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | 1292 B_DIRECT | B_NOWDRAIN); 1293 BUF_UNLOCK(bp); 1294 crit_exit(); 1295 } 1296 1297 /* 1298 * bqrelse: 1299 * 1300 * Release a buffer back to the appropriate queue but do not try to free 1301 * it. The buffer is expected to be used again soon. 1302 * 1303 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1304 * biodone() to requeue an async I/O on completion. It is also used when 1305 * known good buffers need to be requeued but we think we may need the data 1306 * again soon. 1307 * 1308 * XXX we should be able to leave the B_RELBUF hint set on completion. 1309 */ 1310 void 1311 bqrelse(struct buf *bp) 1312 { 1313 crit_enter(); 1314 1315 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1316 1317 if (bp->b_qindex != BQUEUE_NONE) 1318 panic("bqrelse: free buffer onto another queue???"); 1319 if (BUF_REFCNTNB(bp) > 1) { 1320 /* do not release to free list */ 1321 panic("bqrelse: multiple refs"); 1322 BUF_UNLOCK(bp); 1323 crit_exit(); 1324 return; 1325 } 1326 if (bp->b_flags & B_LOCKED) { 1327 /* 1328 * Locked buffers are released to the locked queue. However, 1329 * if the buffer is dirty it will first go into the dirty 1330 * queue and later on after the I/O completes successfully it 1331 * will be released to the locked queue. 1332 */ 1333 bp->b_flags &= ~B_ERROR; 1334 bp->b_qindex = BQUEUE_LOCKED; 1335 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_LOCKED], bp, b_freelist); 1336 } else if (bp->b_flags & B_DELWRI) { 1337 bp->b_qindex = BQUEUE_DIRTY; 1338 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_DIRTY], bp, b_freelist); 1339 } else if (vm_page_count_severe()) { 1340 /* 1341 * We are too low on memory, we have to try to free the 1342 * buffer (most importantly: the wired pages making up its 1343 * backing store) *now*. 1344 */ 1345 crit_exit(); 1346 brelse(bp); 1347 return; 1348 } else { 1349 bp->b_qindex = BQUEUE_CLEAN; 1350 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_CLEAN], bp, b_freelist); 1351 } 1352 1353 if ((bp->b_flags & B_LOCKED) == 0 && 1354 ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0)) { 1355 bufcountwakeup(); 1356 } 1357 1358 /* 1359 * Something we can maybe free or reuse. 1360 */ 1361 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1362 bufspacewakeup(); 1363 1364 /* 1365 * Final cleanup and unlock. Clear bits that are only used while a 1366 * buffer is actively locked. 1367 */ 1368 bp->b_flags &= ~(B_ORDERED | B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1369 BUF_UNLOCK(bp); 1370 crit_exit(); 1371 } 1372 1373 /* 1374 * vfs_vmio_release: 1375 * 1376 * Return backing pages held by the buffer 'bp' back to the VM system 1377 * if possible. The pages are freed if they are no longer valid or 1378 * attempt to free if it was used for direct I/O otherwise they are 1379 * sent to the page cache. 1380 * 1381 * Pages that were marked busy are left alone and skipped. 1382 * 1383 * The KVA mapping (b_data) for the underlying pages is removed by 1384 * this function. 1385 */ 1386 static void 1387 vfs_vmio_release(struct buf *bp) 1388 { 1389 int i; 1390 vm_page_t m; 1391 1392 crit_enter(); 1393 for (i = 0; i < bp->b_xio.xio_npages; i++) { 1394 m = bp->b_xio.xio_pages[i]; 1395 bp->b_xio.xio_pages[i] = NULL; 1396 /* 1397 * In order to keep page LRU ordering consistent, put 1398 * everything on the inactive queue. 1399 */ 1400 vm_page_unwire(m, 0); 1401 /* 1402 * We don't mess with busy pages, it is 1403 * the responsibility of the process that 1404 * busied the pages to deal with them. 1405 */ 1406 if ((m->flags & PG_BUSY) || (m->busy != 0)) 1407 continue; 1408 1409 if (m->wire_count == 0) { 1410 vm_page_flag_clear(m, PG_ZERO); 1411 /* 1412 * Might as well free the page if we can and it has 1413 * no valid data. We also free the page if the 1414 * buffer was used for direct I/O. 1415 */ 1416 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && 1417 m->hold_count == 0) { 1418 vm_page_busy(m); 1419 vm_page_protect(m, VM_PROT_NONE); 1420 vm_page_free(m); 1421 } else if (bp->b_flags & B_DIRECT) { 1422 vm_page_try_to_free(m); 1423 } else if (vm_page_count_severe()) { 1424 vm_page_try_to_cache(m); 1425 } 1426 } 1427 } 1428 crit_exit(); 1429 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_xio.xio_npages); 1430 if (bp->b_bufsize) { 1431 bufspacewakeup(); 1432 bp->b_bufsize = 0; 1433 } 1434 bp->b_xio.xio_npages = 0; 1435 bp->b_flags &= ~B_VMIO; 1436 if (bp->b_vp) 1437 brelvp(bp); 1438 } 1439 1440 /* 1441 * vfs_bio_awrite: 1442 * 1443 * Implement clustered async writes for clearing out B_DELWRI buffers. 1444 * This is much better then the old way of writing only one buffer at 1445 * a time. Note that we may not be presented with the buffers in the 1446 * correct order, so we search for the cluster in both directions. 1447 * 1448 * The buffer is locked on call. 1449 */ 1450 int 1451 vfs_bio_awrite(struct buf *bp) 1452 { 1453 int i; 1454 int j; 1455 off_t loffset = bp->b_loffset; 1456 struct vnode *vp = bp->b_vp; 1457 int nbytes; 1458 struct buf *bpa; 1459 int nwritten; 1460 int size; 1461 1462 crit_enter(); 1463 /* 1464 * right now we support clustered writing only to regular files. If 1465 * we find a clusterable block we could be in the middle of a cluster 1466 * rather then at the beginning. 1467 * 1468 * NOTE: b_bio1 contains the logical loffset and is aliased 1469 * to b_loffset. b_bio2 contains the translated block number. 1470 */ 1471 if ((vp->v_type == VREG) && 1472 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1473 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1474 1475 size = vp->v_mount->mnt_stat.f_iosize; 1476 1477 for (i = size; i < MAXPHYS; i += size) { 1478 if ((bpa = findblk(vp, loffset + i)) && 1479 BUF_REFCNT(bpa) == 0 && 1480 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == 1481 (B_DELWRI | B_CLUSTEROK)) && 1482 (bpa->b_bufsize == size)) { 1483 if ((bpa->b_bio2.bio_offset == NOOFFSET) || 1484 (bpa->b_bio2.bio_offset != 1485 bp->b_bio2.bio_offset + i)) 1486 break; 1487 } else { 1488 break; 1489 } 1490 } 1491 for (j = size; i + j <= MAXPHYS && j <= loffset; j += size) { 1492 if ((bpa = findblk(vp, loffset - j)) && 1493 BUF_REFCNT(bpa) == 0 && 1494 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == 1495 (B_DELWRI | B_CLUSTEROK)) && 1496 (bpa->b_bufsize == size)) { 1497 if ((bpa->b_bio2.bio_offset == NOOFFSET) || 1498 (bpa->b_bio2.bio_offset != 1499 bp->b_bio2.bio_offset - j)) 1500 break; 1501 } else { 1502 break; 1503 } 1504 } 1505 j -= size; 1506 nbytes = (i + j); 1507 /* 1508 * this is a possible cluster write 1509 */ 1510 if (nbytes != size) { 1511 BUF_UNLOCK(bp); 1512 nwritten = cluster_wbuild(vp, size, 1513 loffset - j, nbytes); 1514 crit_exit(); 1515 return nwritten; 1516 } 1517 } 1518 1519 bremfree(bp); 1520 bp->b_flags |= B_ASYNC; 1521 1522 crit_exit(); 1523 /* 1524 * default (old) behavior, writing out only one block 1525 * 1526 * XXX returns b_bufsize instead of b_bcount for nwritten? 1527 */ 1528 nwritten = bp->b_bufsize; 1529 bwrite(bp); 1530 1531 return nwritten; 1532 } 1533 1534 /* 1535 * getnewbuf: 1536 * 1537 * Find and initialize a new buffer header, freeing up existing buffers 1538 * in the bufqueues as necessary. The new buffer is returned locked. 1539 * 1540 * Important: B_INVAL is not set. If the caller wishes to throw the 1541 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1542 * 1543 * We block if: 1544 * We have insufficient buffer headers 1545 * We have insufficient buffer space 1546 * buffer_map is too fragmented ( space reservation fails ) 1547 * If we have to flush dirty buffers ( but we try to avoid this ) 1548 * 1549 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1550 * Instead we ask the buf daemon to do it for us. We attempt to 1551 * avoid piecemeal wakeups of the pageout daemon. 1552 */ 1553 1554 static struct buf * 1555 getnewbuf(int slpflag, int slptimeo, int size, int maxsize) 1556 { 1557 struct buf *bp; 1558 struct buf *nbp; 1559 int defrag = 0; 1560 int nqindex; 1561 static int flushingbufs; 1562 1563 /* 1564 * We can't afford to block since we might be holding a vnode lock, 1565 * which may prevent system daemons from running. We deal with 1566 * low-memory situations by proactively returning memory and running 1567 * async I/O rather then sync I/O. 1568 */ 1569 1570 ++getnewbufcalls; 1571 --getnewbufrestarts; 1572 restart: 1573 ++getnewbufrestarts; 1574 1575 /* 1576 * Setup for scan. If we do not have enough free buffers, 1577 * we setup a degenerate case that immediately fails. Note 1578 * that if we are specially marked process, we are allowed to 1579 * dip into our reserves. 1580 * 1581 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 1582 * 1583 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 1584 * However, there are a number of cases (defragging, reusing, ...) 1585 * where we cannot backup. 1586 */ 1587 nqindex = BQUEUE_EMPTYKVA; 1588 nbp = TAILQ_FIRST(&bufqueues[BQUEUE_EMPTYKVA]); 1589 1590 if (nbp == NULL) { 1591 /* 1592 * If no EMPTYKVA buffers and we are either 1593 * defragging or reusing, locate a CLEAN buffer 1594 * to free or reuse. If bufspace useage is low 1595 * skip this step so we can allocate a new buffer. 1596 */ 1597 if (defrag || bufspace >= lobufspace) { 1598 nqindex = BQUEUE_CLEAN; 1599 nbp = TAILQ_FIRST(&bufqueues[BQUEUE_CLEAN]); 1600 } 1601 1602 /* 1603 * If we could not find or were not allowed to reuse a 1604 * CLEAN buffer, check to see if it is ok to use an EMPTY 1605 * buffer. We can only use an EMPTY buffer if allocating 1606 * its KVA would not otherwise run us out of buffer space. 1607 */ 1608 if (nbp == NULL && defrag == 0 && 1609 bufspace + maxsize < hibufspace) { 1610 nqindex = BQUEUE_EMPTY; 1611 nbp = TAILQ_FIRST(&bufqueues[BQUEUE_EMPTY]); 1612 } 1613 } 1614 1615 /* 1616 * Run scan, possibly freeing data and/or kva mappings on the fly 1617 * depending. 1618 */ 1619 1620 while ((bp = nbp) != NULL) { 1621 int qindex = nqindex; 1622 1623 /* 1624 * Calculate next bp ( we can only use it if we do not block 1625 * or do other fancy things ). 1626 */ 1627 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 1628 switch(qindex) { 1629 case BQUEUE_EMPTY: 1630 nqindex = BQUEUE_EMPTYKVA; 1631 if ((nbp = TAILQ_FIRST(&bufqueues[BQUEUE_EMPTYKVA]))) 1632 break; 1633 /* fall through */ 1634 case BQUEUE_EMPTYKVA: 1635 nqindex = BQUEUE_CLEAN; 1636 if ((nbp = TAILQ_FIRST(&bufqueues[BQUEUE_CLEAN]))) 1637 break; 1638 /* fall through */ 1639 case BQUEUE_CLEAN: 1640 /* 1641 * nbp is NULL. 1642 */ 1643 break; 1644 } 1645 } 1646 1647 /* 1648 * Sanity Checks 1649 */ 1650 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistent queue %d bp %p", qindex, bp)); 1651 1652 /* 1653 * Note: we no longer distinguish between VMIO and non-VMIO 1654 * buffers. 1655 */ 1656 1657 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); 1658 1659 /* 1660 * If we are defragging then we need a buffer with 1661 * b_kvasize != 0. XXX this situation should no longer 1662 * occur, if defrag is non-zero the buffer's b_kvasize 1663 * should also be non-zero at this point. XXX 1664 */ 1665 if (defrag && bp->b_kvasize == 0) { 1666 kprintf("Warning: defrag empty buffer %p\n", bp); 1667 continue; 1668 } 1669 1670 /* 1671 * Start freeing the bp. This is somewhat involved. nbp 1672 * remains valid only for BQUEUE_EMPTY[KVA] bp's. Buffers 1673 * on the clean list must be disassociated from their 1674 * current vnode. Buffers on the empty[kva] lists have 1675 * already been disassociated. 1676 */ 1677 1678 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) { 1679 kprintf("getnewbuf: warning, locked buf %p, race corrected\n", bp); 1680 tsleep(&bd_request, 0, "gnbxxx", hz / 100); 1681 goto restart; 1682 } 1683 if (bp->b_qindex != qindex) { 1684 kprintf("getnewbuf: warning, BUF_LOCK blocked unexpectedly on buf %p index %d->%d, race corrected\n", bp, qindex, bp->b_qindex); 1685 BUF_UNLOCK(bp); 1686 goto restart; 1687 } 1688 bremfree(bp); 1689 1690 /* 1691 * Dependancies must be handled before we disassociate the 1692 * vnode. 1693 * 1694 * NOTE: HAMMER will set B_LOCKED if the buffer cannot 1695 * be immediately disassociated. HAMMER then becomes 1696 * responsible for releasing the buffer. 1697 */ 1698 if (LIST_FIRST(&bp->b_dep) != NULL) { 1699 buf_deallocate(bp); 1700 if (bp->b_flags & B_LOCKED) { 1701 bqrelse(bp); 1702 goto restart; 1703 } 1704 } 1705 1706 if (qindex == BQUEUE_CLEAN) { 1707 if (bp->b_flags & B_VMIO) { 1708 bp->b_flags &= ~B_ASYNC; 1709 vfs_vmio_release(bp); 1710 } 1711 if (bp->b_vp) 1712 brelvp(bp); 1713 } 1714 1715 /* 1716 * NOTE: nbp is now entirely invalid. We can only restart 1717 * the scan from this point on. 1718 * 1719 * Get the rest of the buffer freed up. b_kva* is still 1720 * valid after this operation. 1721 */ 1722 1723 KASSERT(bp->b_vp == NULL, ("bp3 %p flags %08x vnode %p qindex %d unexpectededly still associated!", bp, bp->b_flags, bp->b_vp, qindex)); 1724 KKASSERT((bp->b_flags & B_HASHED) == 0); 1725 1726 /* 1727 * critical section protection is not required when 1728 * scrapping a buffer's contents because it is already 1729 * wired. 1730 */ 1731 if (bp->b_bufsize) 1732 allocbuf(bp, 0); 1733 1734 bp->b_flags = B_BNOCLIP; 1735 bp->b_cmd = BUF_CMD_DONE; 1736 bp->b_vp = NULL; 1737 bp->b_error = 0; 1738 bp->b_resid = 0; 1739 bp->b_bcount = 0; 1740 bp->b_xio.xio_npages = 0; 1741 bp->b_dirtyoff = bp->b_dirtyend = 0; 1742 reinitbufbio(bp); 1743 buf_dep_init(bp); 1744 1745 /* 1746 * If we are defragging then free the buffer. 1747 */ 1748 if (defrag) { 1749 bp->b_flags |= B_INVAL; 1750 bfreekva(bp); 1751 brelse(bp); 1752 defrag = 0; 1753 goto restart; 1754 } 1755 1756 /* 1757 * If we are overcomitted then recover the buffer and its 1758 * KVM space. This occurs in rare situations when multiple 1759 * processes are blocked in getnewbuf() or allocbuf(). 1760 */ 1761 if (bufspace >= hibufspace) 1762 flushingbufs = 1; 1763 if (flushingbufs && bp->b_kvasize != 0) { 1764 bp->b_flags |= B_INVAL; 1765 bfreekva(bp); 1766 brelse(bp); 1767 goto restart; 1768 } 1769 if (bufspace < lobufspace) 1770 flushingbufs = 0; 1771 break; 1772 } 1773 1774 /* 1775 * If we exhausted our list, sleep as appropriate. We may have to 1776 * wakeup various daemons and write out some dirty buffers. 1777 * 1778 * Generally we are sleeping due to insufficient buffer space. 1779 */ 1780 1781 if (bp == NULL) { 1782 int flags; 1783 char *waitmsg; 1784 1785 if (defrag) { 1786 flags = VFS_BIO_NEED_BUFSPACE; 1787 waitmsg = "nbufkv"; 1788 } else if (bufspace >= hibufspace) { 1789 waitmsg = "nbufbs"; 1790 flags = VFS_BIO_NEED_BUFSPACE; 1791 } else { 1792 waitmsg = "newbuf"; 1793 flags = VFS_BIO_NEED_ANY; 1794 } 1795 1796 bd_speedup(); /* heeeelp */ 1797 1798 needsbuffer |= flags; 1799 while (needsbuffer & flags) { 1800 if (tsleep(&needsbuffer, slpflag, waitmsg, slptimeo)) 1801 return (NULL); 1802 } 1803 } else { 1804 /* 1805 * We finally have a valid bp. We aren't quite out of the 1806 * woods, we still have to reserve kva space. In order 1807 * to keep fragmentation sane we only allocate kva in 1808 * BKVASIZE chunks. 1809 */ 1810 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 1811 1812 if (maxsize != bp->b_kvasize) { 1813 vm_offset_t addr = 0; 1814 int count; 1815 1816 bfreekva(bp); 1817 1818 count = vm_map_entry_reserve(MAP_RESERVE_COUNT); 1819 vm_map_lock(&buffer_map); 1820 1821 if (vm_map_findspace(&buffer_map, 1822 vm_map_min(&buffer_map), maxsize, 1823 maxsize, &addr)) { 1824 /* 1825 * Uh oh. Buffer map is too fragmented. We 1826 * must defragment the map. 1827 */ 1828 vm_map_unlock(&buffer_map); 1829 vm_map_entry_release(count); 1830 ++bufdefragcnt; 1831 defrag = 1; 1832 bp->b_flags |= B_INVAL; 1833 brelse(bp); 1834 goto restart; 1835 } 1836 if (addr) { 1837 vm_map_insert(&buffer_map, &count, 1838 NULL, 0, 1839 addr, addr + maxsize, 1840 VM_MAPTYPE_NORMAL, 1841 VM_PROT_ALL, VM_PROT_ALL, 1842 MAP_NOFAULT); 1843 1844 bp->b_kvabase = (caddr_t) addr; 1845 bp->b_kvasize = maxsize; 1846 bufspace += bp->b_kvasize; 1847 ++bufreusecnt; 1848 } 1849 vm_map_unlock(&buffer_map); 1850 vm_map_entry_release(count); 1851 } 1852 bp->b_data = bp->b_kvabase; 1853 } 1854 return(bp); 1855 } 1856 1857 /* 1858 * buf_daemon: 1859 * 1860 * Buffer flushing daemon. Buffers are normally flushed by the 1861 * update daemon but if it cannot keep up this process starts to 1862 * take the load in an attempt to prevent getnewbuf() from blocking. 1863 */ 1864 1865 static struct thread *bufdaemonthread; 1866 1867 static struct kproc_desc buf_kp = { 1868 "bufdaemon", 1869 buf_daemon, 1870 &bufdaemonthread 1871 }; 1872 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp) 1873 1874 static void 1875 buf_daemon(void) 1876 { 1877 /* 1878 * This process needs to be suspended prior to shutdown sync. 1879 */ 1880 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc, 1881 bufdaemonthread, SHUTDOWN_PRI_LAST); 1882 1883 /* 1884 * This process is allowed to take the buffer cache to the limit 1885 */ 1886 crit_enter(); 1887 1888 for (;;) { 1889 kproc_suspend_loop(); 1890 1891 /* 1892 * Do the flush. Limit the amount of in-transit I/O we 1893 * allow to build up, otherwise we would completely saturate 1894 * the I/O system. Wakeup any waiting processes before we 1895 * normally would so they can run in parallel with our drain. 1896 */ 1897 while (numdirtybuffers > lodirtybuffers) { 1898 if (flushbufqueues() == 0) 1899 break; 1900 waitrunningbufspace(); 1901 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 1902 } 1903 1904 /* 1905 * Only clear bd_request if we have reached our low water 1906 * mark. The buf_daemon normally waits 5 seconds and 1907 * then incrementally flushes any dirty buffers that have 1908 * built up, within reason. 1909 * 1910 * If we were unable to hit our low water mark and couldn't 1911 * find any flushable buffers, we sleep half a second. 1912 * Otherwise we loop immediately. 1913 */ 1914 if (numdirtybuffers <= lodirtybuffers) { 1915 /* 1916 * We reached our low water mark, reset the 1917 * request and sleep until we are needed again. 1918 * The sleep is just so the suspend code works. 1919 */ 1920 spin_lock_wr(&needsbuffer_spin); 1921 bd_request = 0; 1922 msleep(&bd_request, &needsbuffer_spin, 0, "psleep", hz); 1923 spin_unlock_wr(&needsbuffer_spin); 1924 } else { 1925 /* 1926 * We couldn't find any flushable dirty buffers but 1927 * still have too many dirty buffers, we 1928 * have to sleep and try again. (rare) 1929 */ 1930 tsleep(&bd_request, 0, "qsleep", hz / 2); 1931 } 1932 } 1933 } 1934 1935 /* 1936 * flushbufqueues: 1937 * 1938 * Try to flush a buffer in the dirty queue. We must be careful to 1939 * free up B_INVAL buffers instead of write them, which NFS is 1940 * particularly sensitive to. 1941 */ 1942 1943 static int 1944 flushbufqueues(void) 1945 { 1946 struct buf *bp; 1947 int r = 0; 1948 1949 bp = TAILQ_FIRST(&bufqueues[BQUEUE_DIRTY]); 1950 1951 while (bp) { 1952 KASSERT((bp->b_flags & B_DELWRI), 1953 ("unexpected clean buffer %p", bp)); 1954 if (bp->b_flags & B_DELWRI) { 1955 if (bp->b_flags & B_INVAL) { 1956 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) 1957 panic("flushbufqueues: locked buf"); 1958 bremfree(bp); 1959 brelse(bp); 1960 ++r; 1961 break; 1962 } 1963 if (LIST_FIRST(&bp->b_dep) != NULL && 1964 (bp->b_flags & B_DEFERRED) == 0 && 1965 buf_countdeps(bp, 0)) { 1966 TAILQ_REMOVE(&bufqueues[BQUEUE_DIRTY], 1967 bp, b_freelist); 1968 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_DIRTY], 1969 bp, b_freelist); 1970 bp->b_flags |= B_DEFERRED; 1971 bp = TAILQ_FIRST(&bufqueues[BQUEUE_DIRTY]); 1972 continue; 1973 } 1974 1975 /* 1976 * Only write it out if we can successfully lock 1977 * it. If the buffer has a dependancy, 1978 * buf_checkwrite must also return 0. 1979 */ 1980 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) == 0) { 1981 if (LIST_FIRST(&bp->b_dep) != NULL && 1982 buf_checkwrite(bp)) { 1983 bremfree(bp); 1984 brelse(bp); 1985 } else { 1986 vfs_bio_awrite(bp); 1987 } 1988 ++r; 1989 break; 1990 } 1991 } 1992 bp = TAILQ_NEXT(bp, b_freelist); 1993 } 1994 return (r); 1995 } 1996 1997 /* 1998 * inmem: 1999 * 2000 * Returns true if no I/O is needed to access the associated VM object. 2001 * This is like findblk except it also hunts around in the VM system for 2002 * the data. 2003 * 2004 * Note that we ignore vm_page_free() races from interrupts against our 2005 * lookup, since if the caller is not protected our return value will not 2006 * be any more valid then otherwise once we exit the critical section. 2007 */ 2008 int 2009 inmem(struct vnode *vp, off_t loffset) 2010 { 2011 vm_object_t obj; 2012 vm_offset_t toff, tinc, size; 2013 vm_page_t m; 2014 2015 if (findblk(vp, loffset)) 2016 return 1; 2017 if (vp->v_mount == NULL) 2018 return 0; 2019 if ((obj = vp->v_object) == NULL) 2020 return 0; 2021 2022 size = PAGE_SIZE; 2023 if (size > vp->v_mount->mnt_stat.f_iosize) 2024 size = vp->v_mount->mnt_stat.f_iosize; 2025 2026 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2027 m = vm_page_lookup(obj, OFF_TO_IDX(loffset + toff)); 2028 if (m == NULL) 2029 return 0; 2030 tinc = size; 2031 if (tinc > PAGE_SIZE - ((toff + loffset) & PAGE_MASK)) 2032 tinc = PAGE_SIZE - ((toff + loffset) & PAGE_MASK); 2033 if (vm_page_is_valid(m, 2034 (vm_offset_t) ((toff + loffset) & PAGE_MASK), tinc) == 0) 2035 return 0; 2036 } 2037 return 1; 2038 } 2039 2040 /* 2041 * vfs_setdirty: 2042 * 2043 * Sets the dirty range for a buffer based on the status of the dirty 2044 * bits in the pages comprising the buffer. 2045 * 2046 * The range is limited to the size of the buffer. 2047 * 2048 * This routine is primarily used by NFS, but is generalized for the 2049 * B_VMIO case. 2050 */ 2051 static void 2052 vfs_setdirty(struct buf *bp) 2053 { 2054 int i; 2055 vm_object_t object; 2056 2057 /* 2058 * Degenerate case - empty buffer 2059 */ 2060 2061 if (bp->b_bufsize == 0) 2062 return; 2063 2064 /* 2065 * We qualify the scan for modified pages on whether the 2066 * object has been flushed yet. The OBJ_WRITEABLE flag 2067 * is not cleared simply by protecting pages off. 2068 */ 2069 2070 if ((bp->b_flags & B_VMIO) == 0) 2071 return; 2072 2073 object = bp->b_xio.xio_pages[0]->object; 2074 2075 if ((object->flags & OBJ_WRITEABLE) && !(object->flags & OBJ_MIGHTBEDIRTY)) 2076 kprintf("Warning: object %p writeable but not mightbedirty\n", object); 2077 if (!(object->flags & OBJ_WRITEABLE) && (object->flags & OBJ_MIGHTBEDIRTY)) 2078 kprintf("Warning: object %p mightbedirty but not writeable\n", object); 2079 2080 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) { 2081 vm_offset_t boffset; 2082 vm_offset_t eoffset; 2083 2084 /* 2085 * test the pages to see if they have been modified directly 2086 * by users through the VM system. 2087 */ 2088 for (i = 0; i < bp->b_xio.xio_npages; i++) { 2089 vm_page_flag_clear(bp->b_xio.xio_pages[i], PG_ZERO); 2090 vm_page_test_dirty(bp->b_xio.xio_pages[i]); 2091 } 2092 2093 /* 2094 * Calculate the encompassing dirty range, boffset and eoffset, 2095 * (eoffset - boffset) bytes. 2096 */ 2097 2098 for (i = 0; i < bp->b_xio.xio_npages; i++) { 2099 if (bp->b_xio.xio_pages[i]->dirty) 2100 break; 2101 } 2102 boffset = (i << PAGE_SHIFT) - (bp->b_loffset & PAGE_MASK); 2103 2104 for (i = bp->b_xio.xio_npages - 1; i >= 0; --i) { 2105 if (bp->b_xio.xio_pages[i]->dirty) { 2106 break; 2107 } 2108 } 2109 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_loffset & PAGE_MASK); 2110 2111 /* 2112 * Fit it to the buffer. 2113 */ 2114 2115 if (eoffset > bp->b_bcount) 2116 eoffset = bp->b_bcount; 2117 2118 /* 2119 * If we have a good dirty range, merge with the existing 2120 * dirty range. 2121 */ 2122 2123 if (boffset < eoffset) { 2124 if (bp->b_dirtyoff > boffset) 2125 bp->b_dirtyoff = boffset; 2126 if (bp->b_dirtyend < eoffset) 2127 bp->b_dirtyend = eoffset; 2128 } 2129 } 2130 } 2131 2132 /* 2133 * findblk: 2134 * 2135 * Locate and return the specified buffer, or NULL if the buffer does 2136 * not exist. Do not attempt to lock the buffer or manipulate it in 2137 * any way. The caller must validate that the correct buffer has been 2138 * obtain after locking it. 2139 */ 2140 struct buf * 2141 findblk(struct vnode *vp, off_t loffset) 2142 { 2143 struct buf *bp; 2144 2145 crit_enter(); 2146 bp = buf_rb_hash_RB_LOOKUP(&vp->v_rbhash_tree, loffset); 2147 crit_exit(); 2148 return(bp); 2149 } 2150 2151 /* 2152 * getblk: 2153 * 2154 * Get a block given a specified block and offset into a file/device. 2155 * B_INVAL may or may not be set on return. The caller should clear 2156 * B_INVAL prior to initiating a READ. 2157 * 2158 * IT IS IMPORTANT TO UNDERSTAND THAT IF YOU CALL GETBLK() AND B_CACHE 2159 * IS NOT SET, YOU MUST INITIALIZE THE RETURNED BUFFER, ISSUE A READ, 2160 * OR SET B_INVAL BEFORE RETIRING IT. If you retire a getblk'd buffer 2161 * without doing any of those things the system will likely believe 2162 * the buffer to be valid (especially if it is not B_VMIO), and the 2163 * next getblk() will return the buffer with B_CACHE set. 2164 * 2165 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2166 * an existing buffer. 2167 * 2168 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2169 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2170 * and then cleared based on the backing VM. If the previous buffer is 2171 * non-0-sized but invalid, B_CACHE will be cleared. 2172 * 2173 * If getblk() must create a new buffer, the new buffer is returned with 2174 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2175 * case it is returned with B_INVAL clear and B_CACHE set based on the 2176 * backing VM. 2177 * 2178 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 2179 * B_CACHE bit is clear. 2180 * 2181 * What this means, basically, is that the caller should use B_CACHE to 2182 * determine whether the buffer is fully valid or not and should clear 2183 * B_INVAL prior to issuing a read. If the caller intends to validate 2184 * the buffer by loading its data area with something, the caller needs 2185 * to clear B_INVAL. If the caller does this without issuing an I/O, 2186 * the caller should set B_CACHE ( as an optimization ), else the caller 2187 * should issue the I/O and biodone() will set B_CACHE if the I/O was 2188 * a write attempt or if it was a successfull read. If the caller 2189 * intends to issue a READ, the caller must clear B_INVAL and B_ERROR 2190 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 2191 */ 2192 struct buf * 2193 getblk(struct vnode *vp, off_t loffset, int size, int slpflag, int slptimeo) 2194 { 2195 struct buf *bp; 2196 2197 if (size > MAXBSIZE) 2198 panic("getblk: size(%d) > MAXBSIZE(%d)", size, MAXBSIZE); 2199 if (vp->v_object == NULL) 2200 panic("getblk: vnode %p has no object!", vp); 2201 2202 crit_enter(); 2203 loop: 2204 /* 2205 * Block if we are low on buffers. Certain processes are allowed 2206 * to completely exhaust the buffer cache. 2207 * 2208 * If this check ever becomes a bottleneck it may be better to 2209 * move it into the else, when findblk() fails. At the moment 2210 * it isn't a problem. 2211 * 2212 * XXX remove, we cannot afford to block anywhere if holding a vnode 2213 * lock in low-memory situation, so take it to the max. 2214 */ 2215 if (numfreebuffers == 0) { 2216 if (!curproc) 2217 return NULL; 2218 needsbuffer |= VFS_BIO_NEED_ANY; 2219 tsleep(&needsbuffer, slpflag, "newbuf", slptimeo); 2220 } 2221 2222 if ((bp = findblk(vp, loffset))) { 2223 /* 2224 * The buffer was found in the cache, but we need to lock it. 2225 * Even with LK_NOWAIT the lockmgr may break our critical 2226 * section, so double-check the validity of the buffer 2227 * once the lock has been obtained. 2228 */ 2229 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) { 2230 int lkflags = LK_EXCLUSIVE | LK_SLEEPFAIL; 2231 if (slpflag & PCATCH) 2232 lkflags |= LK_PCATCH; 2233 if (BUF_TIMELOCK(bp, lkflags, "getblk", slptimeo) == 2234 ENOLCK) { 2235 goto loop; 2236 } 2237 crit_exit(); 2238 return (NULL); 2239 } 2240 2241 /* 2242 * Once the buffer has been locked, make sure we didn't race 2243 * a buffer recyclement. Buffers that are no longer hashed 2244 * will have b_vp == NULL, so this takes care of that check 2245 * as well. 2246 */ 2247 if (bp->b_vp != vp || bp->b_loffset != loffset) { 2248 kprintf("Warning buffer %p (vp %p loffset %lld) was recycled\n", bp, vp, loffset); 2249 BUF_UNLOCK(bp); 2250 goto loop; 2251 } 2252 2253 /* 2254 * All vnode-based buffers must be backed by a VM object. 2255 */ 2256 KKASSERT(bp->b_flags & B_VMIO); 2257 KKASSERT(bp->b_cmd == BUF_CMD_DONE); 2258 2259 /* 2260 * Make sure that B_INVAL buffers do not have a cached 2261 * block number translation. 2262 */ 2263 if ((bp->b_flags & B_INVAL) && (bp->b_bio2.bio_offset != NOOFFSET)) { 2264 kprintf("Warning invalid buffer %p (vp %p loffset %lld) did not have cleared bio_offset cache\n", bp, vp, loffset); 2265 clearbiocache(&bp->b_bio2); 2266 } 2267 2268 /* 2269 * The buffer is locked. B_CACHE is cleared if the buffer is 2270 * invalid. 2271 */ 2272 if (bp->b_flags & B_INVAL) 2273 bp->b_flags &= ~B_CACHE; 2274 bremfree(bp); 2275 2276 /* 2277 * Any size inconsistancy with a dirty buffer or a buffer 2278 * with a softupdates dependancy must be resolved. Resizing 2279 * the buffer in such circumstances can lead to problems. 2280 */ 2281 if (size != bp->b_bcount) { 2282 if (bp->b_flags & B_DELWRI) { 2283 bp->b_flags |= B_NOCACHE; 2284 bwrite(bp); 2285 } else if (LIST_FIRST(&bp->b_dep)) { 2286 bp->b_flags |= B_NOCACHE; 2287 bwrite(bp); 2288 } else { 2289 bp->b_flags |= B_RELBUF; 2290 brelse(bp); 2291 } 2292 goto loop; 2293 } 2294 KKASSERT(size <= bp->b_kvasize); 2295 KASSERT(bp->b_loffset != NOOFFSET, 2296 ("getblk: no buffer offset")); 2297 2298 /* 2299 * A buffer with B_DELWRI set and B_CACHE clear must 2300 * be committed before we can return the buffer in 2301 * order to prevent the caller from issuing a read 2302 * ( due to B_CACHE not being set ) and overwriting 2303 * it. 2304 * 2305 * Most callers, including NFS and FFS, need this to 2306 * operate properly either because they assume they 2307 * can issue a read if B_CACHE is not set, or because 2308 * ( for example ) an uncached B_DELWRI might loop due 2309 * to softupdates re-dirtying the buffer. In the latter 2310 * case, B_CACHE is set after the first write completes, 2311 * preventing further loops. 2312 * 2313 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 2314 * above while extending the buffer, we cannot allow the 2315 * buffer to remain with B_CACHE set after the write 2316 * completes or it will represent a corrupt state. To 2317 * deal with this we set B_NOCACHE to scrap the buffer 2318 * after the write. 2319 * 2320 * We might be able to do something fancy, like setting 2321 * B_CACHE in bwrite() except if B_DELWRI is already set, 2322 * so the below call doesn't set B_CACHE, but that gets real 2323 * confusing. This is much easier. 2324 */ 2325 2326 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 2327 bp->b_flags |= B_NOCACHE; 2328 bwrite(bp); 2329 goto loop; 2330 } 2331 crit_exit(); 2332 } else { 2333 /* 2334 * Buffer is not in-core, create new buffer. The buffer 2335 * returned by getnewbuf() is locked. Note that the returned 2336 * buffer is also considered valid (not marked B_INVAL). 2337 * 2338 * Calculating the offset for the I/O requires figuring out 2339 * the block size. We use DEV_BSIZE for VBLK or VCHR and 2340 * the mount's f_iosize otherwise. If the vnode does not 2341 * have an associated mount we assume that the passed size is 2342 * the block size. 2343 * 2344 * Note that vn_isdisk() cannot be used here since it may 2345 * return a failure for numerous reasons. Note that the 2346 * buffer size may be larger then the block size (the caller 2347 * will use block numbers with the proper multiple). Beware 2348 * of using any v_* fields which are part of unions. In 2349 * particular, in DragonFly the mount point overloading 2350 * mechanism uses the namecache only and the underlying 2351 * directory vnode is not a special case. 2352 */ 2353 int bsize, maxsize; 2354 2355 if (vp->v_type == VBLK || vp->v_type == VCHR) 2356 bsize = DEV_BSIZE; 2357 else if (vp->v_mount) 2358 bsize = vp->v_mount->mnt_stat.f_iosize; 2359 else 2360 bsize = size; 2361 2362 maxsize = size + (loffset & PAGE_MASK); 2363 maxsize = imax(maxsize, bsize); 2364 2365 if ((bp = getnewbuf(slpflag, slptimeo, size, maxsize)) == NULL) { 2366 if (slpflag || slptimeo) { 2367 crit_exit(); 2368 return NULL; 2369 } 2370 goto loop; 2371 } 2372 2373 /* 2374 * This code is used to make sure that a buffer is not 2375 * created while the getnewbuf routine is blocked. 2376 * This can be a problem whether the vnode is locked or not. 2377 * If the buffer is created out from under us, we have to 2378 * throw away the one we just created. There is no window 2379 * race because we are safely running in a critical section 2380 * from the point of the duplicate buffer creation through 2381 * to here, and we've locked the buffer. 2382 */ 2383 if (findblk(vp, loffset)) { 2384 bp->b_flags |= B_INVAL; 2385 brelse(bp); 2386 goto loop; 2387 } 2388 2389 /* 2390 * Insert the buffer into the hash, so that it can 2391 * be found by findblk(). 2392 * 2393 * Make sure the translation layer has been cleared. 2394 */ 2395 bp->b_loffset = loffset; 2396 bp->b_bio2.bio_offset = NOOFFSET; 2397 /* bp->b_bio2.bio_next = NULL; */ 2398 2399 bgetvp(vp, bp); 2400 2401 /* 2402 * All vnode-based buffers must be backed by a VM object. 2403 */ 2404 KKASSERT(vp->v_object != NULL); 2405 bp->b_flags |= B_VMIO; 2406 KKASSERT(bp->b_cmd == BUF_CMD_DONE); 2407 2408 allocbuf(bp, size); 2409 2410 crit_exit(); 2411 } 2412 return (bp); 2413 } 2414 2415 /* 2416 * regetblk(bp) 2417 * 2418 * Reacquire a buffer that was previously released to the locked queue, 2419 * or reacquire a buffer which is interlocked by having bioops->io_deallocate 2420 * set B_LOCKED (which handles the acquisition race). 2421 * 2422 * To this end, either B_LOCKED must be set or the dependancy list must be 2423 * non-empty. 2424 */ 2425 void 2426 regetblk(struct buf *bp) 2427 { 2428 KKASSERT((bp->b_flags & B_LOCKED) || LIST_FIRST(&bp->b_dep) != NULL); 2429 BUF_LOCK(bp, LK_EXCLUSIVE | LK_RETRY); 2430 crit_enter(); 2431 bremfree(bp); 2432 crit_exit(); 2433 } 2434 2435 /* 2436 * geteblk: 2437 * 2438 * Get an empty, disassociated buffer of given size. The buffer is 2439 * initially set to B_INVAL. 2440 * 2441 * critical section protection is not required for the allocbuf() 2442 * call because races are impossible here. 2443 */ 2444 struct buf * 2445 geteblk(int size) 2446 { 2447 struct buf *bp; 2448 int maxsize; 2449 2450 maxsize = (size + BKVAMASK) & ~BKVAMASK; 2451 2452 crit_enter(); 2453 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0) 2454 ; 2455 crit_exit(); 2456 allocbuf(bp, size); 2457 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 2458 return (bp); 2459 } 2460 2461 2462 /* 2463 * allocbuf: 2464 * 2465 * This code constitutes the buffer memory from either anonymous system 2466 * memory (in the case of non-VMIO operations) or from an associated 2467 * VM object (in the case of VMIO operations). This code is able to 2468 * resize a buffer up or down. 2469 * 2470 * Note that this code is tricky, and has many complications to resolve 2471 * deadlock or inconsistant data situations. Tread lightly!!! 2472 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 2473 * the caller. Calling this code willy nilly can result in the loss of data. 2474 * 2475 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 2476 * B_CACHE for the non-VMIO case. 2477 * 2478 * This routine does not need to be called from a critical section but you 2479 * must own the buffer. 2480 */ 2481 int 2482 allocbuf(struct buf *bp, int size) 2483 { 2484 int newbsize, mbsize; 2485 int i; 2486 2487 if (BUF_REFCNT(bp) == 0) 2488 panic("allocbuf: buffer not busy"); 2489 2490 if (bp->b_kvasize < size) 2491 panic("allocbuf: buffer too small"); 2492 2493 if ((bp->b_flags & B_VMIO) == 0) { 2494 caddr_t origbuf; 2495 int origbufsize; 2496 /* 2497 * Just get anonymous memory from the kernel. Don't 2498 * mess with B_CACHE. 2499 */ 2500 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2501 if (bp->b_flags & B_MALLOC) 2502 newbsize = mbsize; 2503 else 2504 newbsize = round_page(size); 2505 2506 if (newbsize < bp->b_bufsize) { 2507 /* 2508 * Malloced buffers are not shrunk 2509 */ 2510 if (bp->b_flags & B_MALLOC) { 2511 if (newbsize) { 2512 bp->b_bcount = size; 2513 } else { 2514 kfree(bp->b_data, M_BIOBUF); 2515 if (bp->b_bufsize) { 2516 bufmallocspace -= bp->b_bufsize; 2517 bufspacewakeup(); 2518 bp->b_bufsize = 0; 2519 } 2520 bp->b_data = bp->b_kvabase; 2521 bp->b_bcount = 0; 2522 bp->b_flags &= ~B_MALLOC; 2523 } 2524 return 1; 2525 } 2526 vm_hold_free_pages( 2527 bp, 2528 (vm_offset_t) bp->b_data + newbsize, 2529 (vm_offset_t) bp->b_data + bp->b_bufsize); 2530 } else if (newbsize > bp->b_bufsize) { 2531 /* 2532 * We only use malloced memory on the first allocation. 2533 * and revert to page-allocated memory when the buffer 2534 * grows. 2535 */ 2536 if ((bufmallocspace < maxbufmallocspace) && 2537 (bp->b_bufsize == 0) && 2538 (mbsize <= PAGE_SIZE/2)) { 2539 2540 bp->b_data = kmalloc(mbsize, M_BIOBUF, M_WAITOK); 2541 bp->b_bufsize = mbsize; 2542 bp->b_bcount = size; 2543 bp->b_flags |= B_MALLOC; 2544 bufmallocspace += mbsize; 2545 return 1; 2546 } 2547 origbuf = NULL; 2548 origbufsize = 0; 2549 /* 2550 * If the buffer is growing on its other-than-first 2551 * allocation, then we revert to the page-allocation 2552 * scheme. 2553 */ 2554 if (bp->b_flags & B_MALLOC) { 2555 origbuf = bp->b_data; 2556 origbufsize = bp->b_bufsize; 2557 bp->b_data = bp->b_kvabase; 2558 if (bp->b_bufsize) { 2559 bufmallocspace -= bp->b_bufsize; 2560 bufspacewakeup(); 2561 bp->b_bufsize = 0; 2562 } 2563 bp->b_flags &= ~B_MALLOC; 2564 newbsize = round_page(newbsize); 2565 } 2566 vm_hold_load_pages( 2567 bp, 2568 (vm_offset_t) bp->b_data + bp->b_bufsize, 2569 (vm_offset_t) bp->b_data + newbsize); 2570 if (origbuf) { 2571 bcopy(origbuf, bp->b_data, origbufsize); 2572 kfree(origbuf, M_BIOBUF); 2573 } 2574 } 2575 } else { 2576 vm_page_t m; 2577 int desiredpages; 2578 2579 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2580 desiredpages = ((int)(bp->b_loffset & PAGE_MASK) + 2581 newbsize + PAGE_MASK) >> PAGE_SHIFT; 2582 KKASSERT(desiredpages <= XIO_INTERNAL_PAGES); 2583 2584 if (bp->b_flags & B_MALLOC) 2585 panic("allocbuf: VMIO buffer can't be malloced"); 2586 /* 2587 * Set B_CACHE initially if buffer is 0 length or will become 2588 * 0-length. 2589 */ 2590 if (size == 0 || bp->b_bufsize == 0) 2591 bp->b_flags |= B_CACHE; 2592 2593 if (newbsize < bp->b_bufsize) { 2594 /* 2595 * DEV_BSIZE aligned new buffer size is less then the 2596 * DEV_BSIZE aligned existing buffer size. Figure out 2597 * if we have to remove any pages. 2598 */ 2599 if (desiredpages < bp->b_xio.xio_npages) { 2600 for (i = desiredpages; i < bp->b_xio.xio_npages; i++) { 2601 /* 2602 * the page is not freed here -- it 2603 * is the responsibility of 2604 * vnode_pager_setsize 2605 */ 2606 m = bp->b_xio.xio_pages[i]; 2607 KASSERT(m != bogus_page, 2608 ("allocbuf: bogus page found")); 2609 while (vm_page_sleep_busy(m, TRUE, "biodep")) 2610 ; 2611 2612 bp->b_xio.xio_pages[i] = NULL; 2613 vm_page_unwire(m, 0); 2614 } 2615 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) + 2616 (desiredpages << PAGE_SHIFT), (bp->b_xio.xio_npages - desiredpages)); 2617 bp->b_xio.xio_npages = desiredpages; 2618 } 2619 } else if (size > bp->b_bcount) { 2620 /* 2621 * We are growing the buffer, possibly in a 2622 * byte-granular fashion. 2623 */ 2624 struct vnode *vp; 2625 vm_object_t obj; 2626 vm_offset_t toff; 2627 vm_offset_t tinc; 2628 2629 /* 2630 * Step 1, bring in the VM pages from the object, 2631 * allocating them if necessary. We must clear 2632 * B_CACHE if these pages are not valid for the 2633 * range covered by the buffer. 2634 * 2635 * critical section protection is required to protect 2636 * against interrupts unbusying and freeing pages 2637 * between our vm_page_lookup() and our 2638 * busycheck/wiring call. 2639 */ 2640 vp = bp->b_vp; 2641 obj = vp->v_object; 2642 2643 crit_enter(); 2644 while (bp->b_xio.xio_npages < desiredpages) { 2645 vm_page_t m; 2646 vm_pindex_t pi; 2647 2648 pi = OFF_TO_IDX(bp->b_loffset) + bp->b_xio.xio_npages; 2649 if ((m = vm_page_lookup(obj, pi)) == NULL) { 2650 /* 2651 * note: must allocate system pages 2652 * since blocking here could intefere 2653 * with paging I/O, no matter which 2654 * process we are. 2655 */ 2656 m = vm_page_alloc(obj, pi, VM_ALLOC_NORMAL | VM_ALLOC_SYSTEM); 2657 if (m == NULL) { 2658 vm_wait(); 2659 vm_pageout_deficit += desiredpages - 2660 bp->b_xio.xio_npages; 2661 } else { 2662 vm_page_wire(m); 2663 vm_page_wakeup(m); 2664 bp->b_flags &= ~B_CACHE; 2665 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 2666 ++bp->b_xio.xio_npages; 2667 } 2668 continue; 2669 } 2670 2671 /* 2672 * We found a page. If we have to sleep on it, 2673 * retry because it might have gotten freed out 2674 * from under us. 2675 * 2676 * We can only test PG_BUSY here. Blocking on 2677 * m->busy might lead to a deadlock: 2678 * 2679 * vm_fault->getpages->cluster_read->allocbuf 2680 * 2681 */ 2682 2683 if (vm_page_sleep_busy(m, FALSE, "pgtblk")) 2684 continue; 2685 2686 /* 2687 * We have a good page. Should we wakeup the 2688 * page daemon? 2689 */ 2690 if ((curthread != pagethread) && 2691 ((m->queue - m->pc) == PQ_CACHE) && 2692 ((vmstats.v_free_count + vmstats.v_cache_count) < 2693 (vmstats.v_free_min + vmstats.v_cache_min))) { 2694 pagedaemon_wakeup(); 2695 } 2696 vm_page_flag_clear(m, PG_ZERO); 2697 vm_page_wire(m); 2698 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 2699 ++bp->b_xio.xio_npages; 2700 } 2701 crit_exit(); 2702 2703 /* 2704 * Step 2. We've loaded the pages into the buffer, 2705 * we have to figure out if we can still have B_CACHE 2706 * set. Note that B_CACHE is set according to the 2707 * byte-granular range ( bcount and size ), not the 2708 * aligned range ( newbsize ). 2709 * 2710 * The VM test is against m->valid, which is DEV_BSIZE 2711 * aligned. Needless to say, the validity of the data 2712 * needs to also be DEV_BSIZE aligned. Note that this 2713 * fails with NFS if the server or some other client 2714 * extends the file's EOF. If our buffer is resized, 2715 * B_CACHE may remain set! XXX 2716 */ 2717 2718 toff = bp->b_bcount; 2719 tinc = PAGE_SIZE - ((bp->b_loffset + toff) & PAGE_MASK); 2720 2721 while ((bp->b_flags & B_CACHE) && toff < size) { 2722 vm_pindex_t pi; 2723 2724 if (tinc > (size - toff)) 2725 tinc = size - toff; 2726 2727 pi = ((bp->b_loffset & PAGE_MASK) + toff) >> 2728 PAGE_SHIFT; 2729 2730 vfs_buf_test_cache( 2731 bp, 2732 bp->b_loffset, 2733 toff, 2734 tinc, 2735 bp->b_xio.xio_pages[pi] 2736 ); 2737 toff += tinc; 2738 tinc = PAGE_SIZE; 2739 } 2740 2741 /* 2742 * Step 3, fixup the KVM pmap. Remember that 2743 * bp->b_data is relative to bp->b_loffset, but 2744 * bp->b_loffset may be offset into the first page. 2745 */ 2746 2747 bp->b_data = (caddr_t) 2748 trunc_page((vm_offset_t)bp->b_data); 2749 pmap_qenter( 2750 (vm_offset_t)bp->b_data, 2751 bp->b_xio.xio_pages, 2752 bp->b_xio.xio_npages 2753 ); 2754 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 2755 (vm_offset_t)(bp->b_loffset & PAGE_MASK)); 2756 } 2757 } 2758 if (newbsize < bp->b_bufsize) 2759 bufspacewakeup(); 2760 bp->b_bufsize = newbsize; /* actual buffer allocation */ 2761 bp->b_bcount = size; /* requested buffer size */ 2762 return 1; 2763 } 2764 2765 /* 2766 * biowait: 2767 * 2768 * Wait for buffer I/O completion, returning error status. The buffer 2769 * is left locked on return. B_EINTR is converted into an EINTR error 2770 * and cleared. 2771 * 2772 * NOTE! The original b_cmd is lost on return, since b_cmd will be 2773 * set to BUF_CMD_DONE. 2774 */ 2775 int 2776 biowait(struct buf *bp) 2777 { 2778 crit_enter(); 2779 while (bp->b_cmd != BUF_CMD_DONE) { 2780 if (bp->b_cmd == BUF_CMD_READ) 2781 tsleep(bp, 0, "biord", 0); 2782 else 2783 tsleep(bp, 0, "biowr", 0); 2784 } 2785 crit_exit(); 2786 if (bp->b_flags & B_EINTR) { 2787 bp->b_flags &= ~B_EINTR; 2788 return (EINTR); 2789 } 2790 if (bp->b_flags & B_ERROR) { 2791 return (bp->b_error ? bp->b_error : EIO); 2792 } else { 2793 return (0); 2794 } 2795 } 2796 2797 /* 2798 * This associates a tracking count with an I/O. vn_strategy() and 2799 * dev_dstrategy() do this automatically but there are a few cases 2800 * where a vnode or device layer is bypassed when a block translation 2801 * is cached. In such cases bio_start_transaction() may be called on 2802 * the bypassed layers so the system gets an I/O in progress indication 2803 * for those higher layers. 2804 */ 2805 void 2806 bio_start_transaction(struct bio *bio, struct bio_track *track) 2807 { 2808 bio->bio_track = track; 2809 atomic_add_int(&track->bk_active, 1); 2810 } 2811 2812 /* 2813 * Initiate I/O on a vnode. 2814 */ 2815 void 2816 vn_strategy(struct vnode *vp, struct bio *bio) 2817 { 2818 struct bio_track *track; 2819 2820 KKASSERT(bio->bio_buf->b_cmd != BUF_CMD_DONE); 2821 if (bio->bio_buf->b_cmd == BUF_CMD_READ) 2822 track = &vp->v_track_read; 2823 else 2824 track = &vp->v_track_write; 2825 bio->bio_track = track; 2826 atomic_add_int(&track->bk_active, 1); 2827 vop_strategy(*vp->v_ops, vp, bio); 2828 } 2829 2830 2831 /* 2832 * biodone: 2833 * 2834 * Finish I/O on a buffer, optionally calling a completion function. 2835 * This is usually called from an interrupt so process blocking is 2836 * not allowed. 2837 * 2838 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 2839 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 2840 * assuming B_INVAL is clear. 2841 * 2842 * For the VMIO case, we set B_CACHE if the op was a read and no 2843 * read error occured, or if the op was a write. B_CACHE is never 2844 * set if the buffer is invalid or otherwise uncacheable. 2845 * 2846 * biodone does not mess with B_INVAL, allowing the I/O routine or the 2847 * initiator to leave B_INVAL set to brelse the buffer out of existance 2848 * in the biodone routine. 2849 */ 2850 void 2851 biodone(struct bio *bio) 2852 { 2853 struct buf *bp = bio->bio_buf; 2854 buf_cmd_t cmd; 2855 2856 crit_enter(); 2857 2858 KASSERT(BUF_REFCNTNB(bp) > 0, 2859 ("biodone: bp %p not busy %d", bp, BUF_REFCNTNB(bp))); 2860 KASSERT(bp->b_cmd != BUF_CMD_DONE, 2861 ("biodone: bp %p already done!", bp)); 2862 2863 runningbufwakeup(bp); 2864 2865 /* 2866 * Run up the chain of BIO's. Leave b_cmd intact for the duration. 2867 */ 2868 while (bio) { 2869 biodone_t *done_func; 2870 struct bio_track *track; 2871 2872 /* 2873 * BIO tracking. Most but not all BIOs are tracked. 2874 */ 2875 if ((track = bio->bio_track) != NULL) { 2876 atomic_subtract_int(&track->bk_active, 1); 2877 if (track->bk_active < 0) { 2878 panic("biodone: bad active count bio %p\n", 2879 bio); 2880 } 2881 if (track->bk_waitflag) { 2882 track->bk_waitflag = 0; 2883 wakeup(track); 2884 } 2885 bio->bio_track = NULL; 2886 } 2887 2888 /* 2889 * A bio_done function terminates the loop. The function 2890 * will be responsible for any further chaining and/or 2891 * buffer management. 2892 * 2893 * WARNING! The done function can deallocate the buffer! 2894 */ 2895 if ((done_func = bio->bio_done) != NULL) { 2896 bio->bio_done = NULL; 2897 done_func(bio); 2898 crit_exit(); 2899 return; 2900 } 2901 bio = bio->bio_prev; 2902 } 2903 2904 cmd = bp->b_cmd; 2905 bp->b_cmd = BUF_CMD_DONE; 2906 2907 /* 2908 * Only reads and writes are processed past this point. 2909 */ 2910 if (cmd != BUF_CMD_READ && cmd != BUF_CMD_WRITE) { 2911 brelse(bp); 2912 crit_exit(); 2913 return; 2914 } 2915 2916 /* 2917 * Warning: softupdates may re-dirty the buffer. 2918 */ 2919 if (LIST_FIRST(&bp->b_dep) != NULL) 2920 buf_complete(bp); 2921 2922 if (bp->b_flags & B_VMIO) { 2923 int i; 2924 vm_ooffset_t foff; 2925 vm_page_t m; 2926 vm_object_t obj; 2927 int iosize; 2928 struct vnode *vp = bp->b_vp; 2929 2930 obj = vp->v_object; 2931 2932 #if defined(VFS_BIO_DEBUG) 2933 if (vp->v_auxrefs == 0) 2934 panic("biodone: zero vnode hold count"); 2935 if ((vp->v_flag & VOBJBUF) == 0) 2936 panic("biodone: vnode is not setup for merged cache"); 2937 #endif 2938 2939 foff = bp->b_loffset; 2940 KASSERT(foff != NOOFFSET, ("biodone: no buffer offset")); 2941 KASSERT(obj != NULL, ("biodone: missing VM object")); 2942 2943 #if defined(VFS_BIO_DEBUG) 2944 if (obj->paging_in_progress < bp->b_xio.xio_npages) { 2945 kprintf("biodone: paging in progress(%d) < bp->b_xio.xio_npages(%d)\n", 2946 obj->paging_in_progress, bp->b_xio.xio_npages); 2947 } 2948 #endif 2949 2950 /* 2951 * Set B_CACHE if the op was a normal read and no error 2952 * occured. B_CACHE is set for writes in the b*write() 2953 * routines. 2954 */ 2955 iosize = bp->b_bcount - bp->b_resid; 2956 if (cmd == BUF_CMD_READ && (bp->b_flags & (B_INVAL|B_NOCACHE|B_ERROR)) == 0) { 2957 bp->b_flags |= B_CACHE; 2958 } 2959 2960 for (i = 0; i < bp->b_xio.xio_npages; i++) { 2961 int bogusflag = 0; 2962 int resid; 2963 2964 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 2965 if (resid > iosize) 2966 resid = iosize; 2967 2968 /* 2969 * cleanup bogus pages, restoring the originals. Since 2970 * the originals should still be wired, we don't have 2971 * to worry about interrupt/freeing races destroying 2972 * the VM object association. 2973 */ 2974 m = bp->b_xio.xio_pages[i]; 2975 if (m == bogus_page) { 2976 bogusflag = 1; 2977 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 2978 if (m == NULL) 2979 panic("biodone: page disappeared"); 2980 bp->b_xio.xio_pages[i] = m; 2981 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 2982 bp->b_xio.xio_pages, bp->b_xio.xio_npages); 2983 } 2984 #if defined(VFS_BIO_DEBUG) 2985 if (OFF_TO_IDX(foff) != m->pindex) { 2986 kprintf( 2987 "biodone: foff(%lu)/m->pindex(%d) mismatch\n", 2988 (unsigned long)foff, m->pindex); 2989 } 2990 #endif 2991 2992 /* 2993 * In the write case, the valid and clean bits are 2994 * already changed correctly ( see bdwrite() ), so we 2995 * only need to do this here in the read case. 2996 */ 2997 if (cmd == BUF_CMD_READ && !bogusflag && resid > 0) { 2998 vfs_page_set_valid(bp, foff, i, m); 2999 } 3000 vm_page_flag_clear(m, PG_ZERO); 3001 3002 /* 3003 * when debugging new filesystems or buffer I/O methods, this 3004 * is the most common error that pops up. if you see this, you 3005 * have not set the page busy flag correctly!!! 3006 */ 3007 if (m->busy == 0) { 3008 kprintf("biodone: page busy < 0, " 3009 "pindex: %d, foff: 0x(%x,%x), " 3010 "resid: %d, index: %d\n", 3011 (int) m->pindex, (int)(foff >> 32), 3012 (int) foff & 0xffffffff, resid, i); 3013 if (!vn_isdisk(vp, NULL)) 3014 kprintf(" iosize: %ld, loffset: %lld, flags: 0x%08x, npages: %d\n", 3015 bp->b_vp->v_mount->mnt_stat.f_iosize, 3016 bp->b_loffset, 3017 bp->b_flags, bp->b_xio.xio_npages); 3018 else 3019 kprintf(" VDEV, loffset: %lld, flags: 0x%08x, npages: %d\n", 3020 bp->b_loffset, 3021 bp->b_flags, bp->b_xio.xio_npages); 3022 kprintf(" valid: 0x%x, dirty: 0x%x, wired: %d\n", 3023 m->valid, m->dirty, m->wire_count); 3024 panic("biodone: page busy < 0"); 3025 } 3026 vm_page_io_finish(m); 3027 vm_object_pip_subtract(obj, 1); 3028 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3029 iosize -= resid; 3030 } 3031 if (obj) 3032 vm_object_pip_wakeupn(obj, 0); 3033 } 3034 3035 /* 3036 * For asynchronous completions, release the buffer now. The brelse 3037 * will do a wakeup there if necessary - so no need to do a wakeup 3038 * here in the async case. The sync case always needs to do a wakeup. 3039 */ 3040 3041 if (bp->b_flags & B_ASYNC) { 3042 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR | B_RELBUF)) != 0) 3043 brelse(bp); 3044 else 3045 bqrelse(bp); 3046 } else { 3047 wakeup(bp); 3048 } 3049 crit_exit(); 3050 } 3051 3052 /* 3053 * vfs_unbusy_pages: 3054 * 3055 * This routine is called in lieu of iodone in the case of 3056 * incomplete I/O. This keeps the busy status for pages 3057 * consistant. 3058 */ 3059 void 3060 vfs_unbusy_pages(struct buf *bp) 3061 { 3062 int i; 3063 3064 runningbufwakeup(bp); 3065 if (bp->b_flags & B_VMIO) { 3066 struct vnode *vp = bp->b_vp; 3067 vm_object_t obj; 3068 3069 obj = vp->v_object; 3070 3071 for (i = 0; i < bp->b_xio.xio_npages; i++) { 3072 vm_page_t m = bp->b_xio.xio_pages[i]; 3073 3074 /* 3075 * When restoring bogus changes the original pages 3076 * should still be wired, so we are in no danger of 3077 * losing the object association and do not need 3078 * critical section protection particularly. 3079 */ 3080 if (m == bogus_page) { 3081 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_loffset) + i); 3082 if (!m) { 3083 panic("vfs_unbusy_pages: page missing"); 3084 } 3085 bp->b_xio.xio_pages[i] = m; 3086 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3087 bp->b_xio.xio_pages, bp->b_xio.xio_npages); 3088 } 3089 vm_object_pip_subtract(obj, 1); 3090 vm_page_flag_clear(m, PG_ZERO); 3091 vm_page_io_finish(m); 3092 } 3093 vm_object_pip_wakeupn(obj, 0); 3094 } 3095 } 3096 3097 /* 3098 * vfs_page_set_valid: 3099 * 3100 * Set the valid bits in a page based on the supplied offset. The 3101 * range is restricted to the buffer's size. 3102 * 3103 * This routine is typically called after a read completes. 3104 */ 3105 static void 3106 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m) 3107 { 3108 vm_ooffset_t soff, eoff; 3109 3110 /* 3111 * Start and end offsets in buffer. eoff - soff may not cross a 3112 * page boundry or cross the end of the buffer. The end of the 3113 * buffer, in this case, is our file EOF, not the allocation size 3114 * of the buffer. 3115 */ 3116 soff = off; 3117 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3118 if (eoff > bp->b_loffset + bp->b_bcount) 3119 eoff = bp->b_loffset + bp->b_bcount; 3120 3121 /* 3122 * Set valid range. This is typically the entire buffer and thus the 3123 * entire page. 3124 */ 3125 if (eoff > soff) { 3126 vm_page_set_validclean( 3127 m, 3128 (vm_offset_t) (soff & PAGE_MASK), 3129 (vm_offset_t) (eoff - soff) 3130 ); 3131 } 3132 } 3133 3134 /* 3135 * vfs_busy_pages: 3136 * 3137 * This routine is called before a device strategy routine. 3138 * It is used to tell the VM system that paging I/O is in 3139 * progress, and treat the pages associated with the buffer 3140 * almost as being PG_BUSY. Also the object 'paging_in_progress' 3141 * flag is handled to make sure that the object doesn't become 3142 * inconsistant. 3143 * 3144 * Since I/O has not been initiated yet, certain buffer flags 3145 * such as B_ERROR or B_INVAL may be in an inconsistant state 3146 * and should be ignored. 3147 */ 3148 void 3149 vfs_busy_pages(struct vnode *vp, struct buf *bp) 3150 { 3151 int i, bogus; 3152 struct lwp *lp = curthread->td_lwp; 3153 3154 /* 3155 * The buffer's I/O command must already be set. If reading, 3156 * B_CACHE must be 0 (double check against callers only doing 3157 * I/O when B_CACHE is 0). 3158 */ 3159 KKASSERT(bp->b_cmd != BUF_CMD_DONE); 3160 KKASSERT(bp->b_cmd == BUF_CMD_WRITE || (bp->b_flags & B_CACHE) == 0); 3161 3162 if (bp->b_flags & B_VMIO) { 3163 vm_object_t obj; 3164 vm_ooffset_t foff; 3165 3166 obj = vp->v_object; 3167 foff = bp->b_loffset; 3168 KASSERT(bp->b_loffset != NOOFFSET, 3169 ("vfs_busy_pages: no buffer offset")); 3170 vfs_setdirty(bp); 3171 3172 retry: 3173 for (i = 0; i < bp->b_xio.xio_npages; i++) { 3174 vm_page_t m = bp->b_xio.xio_pages[i]; 3175 if (vm_page_sleep_busy(m, FALSE, "vbpage")) 3176 goto retry; 3177 } 3178 3179 bogus = 0; 3180 for (i = 0; i < bp->b_xio.xio_npages; i++) { 3181 vm_page_t m = bp->b_xio.xio_pages[i]; 3182 3183 vm_page_flag_clear(m, PG_ZERO); 3184 if ((bp->b_flags & B_CLUSTER) == 0) { 3185 vm_object_pip_add(obj, 1); 3186 vm_page_io_start(m); 3187 } 3188 3189 /* 3190 * When readying a vnode-backed buffer for a write 3191 * we must zero-fill any invalid portions of the 3192 * backing VM pages. 3193 * 3194 * When readying a vnode-backed buffer for a read 3195 * we must replace any dirty pages with a bogus 3196 * page so we do not destroy dirty data when 3197 * filling in gaps. Dirty pages might not 3198 * necessarily be marked dirty yet, so use m->valid 3199 * as a reasonable test. 3200 * 3201 * Bogus page replacement is, uh, bogus. We need 3202 * to find a better way. 3203 */ 3204 vm_page_protect(m, VM_PROT_NONE); 3205 if (bp->b_cmd == BUF_CMD_WRITE) { 3206 vfs_page_set_valid(bp, foff, i, m); 3207 } else if (m->valid == VM_PAGE_BITS_ALL) { 3208 bp->b_xio.xio_pages[i] = bogus_page; 3209 bogus++; 3210 } 3211 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3212 } 3213 if (bogus) 3214 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3215 bp->b_xio.xio_pages, bp->b_xio.xio_npages); 3216 } 3217 3218 /* 3219 * This is the easiest place to put the process accounting for the I/O 3220 * for now. 3221 */ 3222 if (lp != NULL) { 3223 if (bp->b_cmd == BUF_CMD_READ) 3224 lp->lwp_ru.ru_inblock++; 3225 else 3226 lp->lwp_ru.ru_oublock++; 3227 } 3228 } 3229 3230 /* 3231 * vfs_clean_pages: 3232 * 3233 * Tell the VM system that the pages associated with this buffer 3234 * are clean. This is used for delayed writes where the data is 3235 * going to go to disk eventually without additional VM intevention. 3236 * 3237 * Note that while we only really need to clean through to b_bcount, we 3238 * just go ahead and clean through to b_bufsize. 3239 */ 3240 static void 3241 vfs_clean_pages(struct buf *bp) 3242 { 3243 int i; 3244 3245 if (bp->b_flags & B_VMIO) { 3246 vm_ooffset_t foff; 3247 3248 foff = bp->b_loffset; 3249 KASSERT(foff != NOOFFSET, ("vfs_clean_pages: no buffer offset")); 3250 for (i = 0; i < bp->b_xio.xio_npages; i++) { 3251 vm_page_t m = bp->b_xio.xio_pages[i]; 3252 vm_ooffset_t noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3253 vm_ooffset_t eoff = noff; 3254 3255 if (eoff > bp->b_loffset + bp->b_bufsize) 3256 eoff = bp->b_loffset + bp->b_bufsize; 3257 vfs_page_set_valid(bp, foff, i, m); 3258 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3259 foff = noff; 3260 } 3261 } 3262 } 3263 3264 /* 3265 * vfs_bio_set_validclean: 3266 * 3267 * Set the range within the buffer to valid and clean. The range is 3268 * relative to the beginning of the buffer, b_loffset. Note that 3269 * b_loffset itself may be offset from the beginning of the first page. 3270 */ 3271 3272 void 3273 vfs_bio_set_validclean(struct buf *bp, int base, int size) 3274 { 3275 if (bp->b_flags & B_VMIO) { 3276 int i; 3277 int n; 3278 3279 /* 3280 * Fixup base to be relative to beginning of first page. 3281 * Set initial n to be the maximum number of bytes in the 3282 * first page that can be validated. 3283 */ 3284 3285 base += (bp->b_loffset & PAGE_MASK); 3286 n = PAGE_SIZE - (base & PAGE_MASK); 3287 3288 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_xio.xio_npages; ++i) { 3289 vm_page_t m = bp->b_xio.xio_pages[i]; 3290 3291 if (n > size) 3292 n = size; 3293 3294 vm_page_set_validclean(m, base & PAGE_MASK, n); 3295 base += n; 3296 size -= n; 3297 n = PAGE_SIZE; 3298 } 3299 } 3300 } 3301 3302 /* 3303 * vfs_bio_clrbuf: 3304 * 3305 * Clear a buffer. This routine essentially fakes an I/O, so we need 3306 * to clear B_ERROR and B_INVAL. 3307 * 3308 * Note that while we only theoretically need to clear through b_bcount, 3309 * we go ahead and clear through b_bufsize. 3310 */ 3311 3312 void 3313 vfs_bio_clrbuf(struct buf *bp) 3314 { 3315 int i, mask = 0; 3316 caddr_t sa, ea; 3317 if ((bp->b_flags & (B_VMIO | B_MALLOC)) == B_VMIO) { 3318 bp->b_flags &= ~(B_INVAL|B_ERROR); 3319 if ((bp->b_xio.xio_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 3320 (bp->b_loffset & PAGE_MASK) == 0) { 3321 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 3322 if ((bp->b_xio.xio_pages[0]->valid & mask) == mask) { 3323 bp->b_resid = 0; 3324 return; 3325 } 3326 if (((bp->b_xio.xio_pages[0]->flags & PG_ZERO) == 0) && 3327 ((bp->b_xio.xio_pages[0]->valid & mask) == 0)) { 3328 bzero(bp->b_data, bp->b_bufsize); 3329 bp->b_xio.xio_pages[0]->valid |= mask; 3330 bp->b_resid = 0; 3331 return; 3332 } 3333 } 3334 ea = sa = bp->b_data; 3335 for(i=0;i<bp->b_xio.xio_npages;i++,sa=ea) { 3336 int j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; 3337 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); 3338 ea = (caddr_t)(vm_offset_t)ulmin( 3339 (u_long)(vm_offset_t)ea, 3340 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); 3341 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 3342 if ((bp->b_xio.xio_pages[i]->valid & mask) == mask) 3343 continue; 3344 if ((bp->b_xio.xio_pages[i]->valid & mask) == 0) { 3345 if ((bp->b_xio.xio_pages[i]->flags & PG_ZERO) == 0) { 3346 bzero(sa, ea - sa); 3347 } 3348 } else { 3349 for (; sa < ea; sa += DEV_BSIZE, j++) { 3350 if (((bp->b_xio.xio_pages[i]->flags & PG_ZERO) == 0) && 3351 (bp->b_xio.xio_pages[i]->valid & (1<<j)) == 0) 3352 bzero(sa, DEV_BSIZE); 3353 } 3354 } 3355 bp->b_xio.xio_pages[i]->valid |= mask; 3356 vm_page_flag_clear(bp->b_xio.xio_pages[i], PG_ZERO); 3357 } 3358 bp->b_resid = 0; 3359 } else { 3360 clrbuf(bp); 3361 } 3362 } 3363 3364 /* 3365 * vm_hold_load_pages: 3366 * 3367 * Load pages into the buffer's address space. The pages are 3368 * allocated from the kernel object in order to reduce interference 3369 * with the any VM paging I/O activity. The range of loaded 3370 * pages will be wired. 3371 * 3372 * If a page cannot be allocated, the 'pagedaemon' is woken up to 3373 * retrieve the full range (to - from) of pages. 3374 * 3375 */ 3376 void 3377 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 3378 { 3379 vm_offset_t pg; 3380 vm_page_t p; 3381 int index; 3382 3383 to = round_page(to); 3384 from = round_page(from); 3385 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3386 3387 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3388 3389 tryagain: 3390 3391 /* 3392 * Note: must allocate system pages since blocking here 3393 * could intefere with paging I/O, no matter which 3394 * process we are. 3395 */ 3396 p = vm_page_alloc(&kernel_object, 3397 (pg >> PAGE_SHIFT), 3398 VM_ALLOC_NORMAL | VM_ALLOC_SYSTEM); 3399 if (!p) { 3400 vm_pageout_deficit += (to - from) >> PAGE_SHIFT; 3401 vm_wait(); 3402 goto tryagain; 3403 } 3404 vm_page_wire(p); 3405 p->valid = VM_PAGE_BITS_ALL; 3406 vm_page_flag_clear(p, PG_ZERO); 3407 pmap_kenter(pg, VM_PAGE_TO_PHYS(p)); 3408 bp->b_xio.xio_pages[index] = p; 3409 vm_page_wakeup(p); 3410 } 3411 bp->b_xio.xio_npages = index; 3412 } 3413 3414 /* 3415 * vm_hold_free_pages: 3416 * 3417 * Return pages associated with the buffer back to the VM system. 3418 * 3419 * The range of pages underlying the buffer's address space will 3420 * be unmapped and un-wired. 3421 */ 3422 void 3423 vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 3424 { 3425 vm_offset_t pg; 3426 vm_page_t p; 3427 int index, newnpages; 3428 3429 from = round_page(from); 3430 to = round_page(to); 3431 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3432 3433 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3434 p = bp->b_xio.xio_pages[index]; 3435 if (p && (index < bp->b_xio.xio_npages)) { 3436 if (p->busy) { 3437 kprintf("vm_hold_free_pages: doffset: %lld, loffset: %lld\n", 3438 bp->b_bio2.bio_offset, bp->b_loffset); 3439 } 3440 bp->b_xio.xio_pages[index] = NULL; 3441 pmap_kremove(pg); 3442 vm_page_busy(p); 3443 vm_page_unwire(p, 0); 3444 vm_page_free(p); 3445 } 3446 } 3447 bp->b_xio.xio_npages = newnpages; 3448 } 3449 3450 /* 3451 * vmapbuf: 3452 * 3453 * Map a user buffer into KVM via a pbuf. On return the buffer's 3454 * b_data, b_bufsize, and b_bcount will be set, and its XIO page array 3455 * initialized. 3456 */ 3457 int 3458 vmapbuf(struct buf *bp, caddr_t udata, int bytes) 3459 { 3460 caddr_t addr; 3461 vm_offset_t va; 3462 vm_page_t m; 3463 int vmprot; 3464 int error; 3465 int pidx; 3466 int i; 3467 3468 /* 3469 * bp had better have a command and it better be a pbuf. 3470 */ 3471 KKASSERT(bp->b_cmd != BUF_CMD_DONE); 3472 KKASSERT(bp->b_flags & B_PAGING); 3473 3474 if (bytes < 0) 3475 return (-1); 3476 3477 /* 3478 * Map the user data into KVM. Mappings have to be page-aligned. 3479 */ 3480 addr = (caddr_t)trunc_page((vm_offset_t)udata); 3481 pidx = 0; 3482 3483 vmprot = VM_PROT_READ; 3484 if (bp->b_cmd == BUF_CMD_READ) 3485 vmprot |= VM_PROT_WRITE; 3486 3487 while (addr < udata + bytes) { 3488 /* 3489 * Do the vm_fault if needed; do the copy-on-write thing 3490 * when reading stuff off device into memory. 3491 * 3492 * vm_fault_page*() returns a held VM page. 3493 */ 3494 va = (addr >= udata) ? (vm_offset_t)addr : (vm_offset_t)udata; 3495 va = trunc_page(va); 3496 3497 m = vm_fault_page_quick(va, vmprot, &error); 3498 if (m == NULL) { 3499 for (i = 0; i < pidx; ++i) { 3500 vm_page_unhold(bp->b_xio.xio_pages[i]); 3501 bp->b_xio.xio_pages[i] = NULL; 3502 } 3503 return(-1); 3504 } 3505 bp->b_xio.xio_pages[pidx] = m; 3506 addr += PAGE_SIZE; 3507 ++pidx; 3508 } 3509 3510 /* 3511 * Map the page array and set the buffer fields to point to 3512 * the mapped data buffer. 3513 */ 3514 if (pidx > btoc(MAXPHYS)) 3515 panic("vmapbuf: mapped more than MAXPHYS"); 3516 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_xio.xio_pages, pidx); 3517 3518 bp->b_xio.xio_npages = pidx; 3519 bp->b_data = bp->b_kvabase + ((int)(intptr_t)udata & PAGE_MASK); 3520 bp->b_bcount = bytes; 3521 bp->b_bufsize = bytes; 3522 return(0); 3523 } 3524 3525 /* 3526 * vunmapbuf: 3527 * 3528 * Free the io map PTEs associated with this IO operation. 3529 * We also invalidate the TLB entries and restore the original b_addr. 3530 */ 3531 void 3532 vunmapbuf(struct buf *bp) 3533 { 3534 int pidx; 3535 int npages; 3536 3537 KKASSERT(bp->b_flags & B_PAGING); 3538 3539 npages = bp->b_xio.xio_npages; 3540 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 3541 for (pidx = 0; pidx < npages; ++pidx) { 3542 vm_page_unhold(bp->b_xio.xio_pages[pidx]); 3543 bp->b_xio.xio_pages[pidx] = NULL; 3544 } 3545 bp->b_xio.xio_npages = 0; 3546 bp->b_data = bp->b_kvabase; 3547 } 3548 3549 /* 3550 * Scan all buffers in the system and issue the callback. 3551 */ 3552 int 3553 scan_all_buffers(int (*callback)(struct buf *, void *), void *info) 3554 { 3555 int count = 0; 3556 int error; 3557 int n; 3558 3559 for (n = 0; n < nbuf; ++n) { 3560 if ((error = callback(&buf[n], info)) < 0) { 3561 count = error; 3562 break; 3563 } 3564 count += error; 3565 } 3566 return (count); 3567 } 3568 3569 /* 3570 * print out statistics from the current status of the buffer pool 3571 * this can be toggeled by the system control option debug.syncprt 3572 */ 3573 #ifdef DEBUG 3574 void 3575 vfs_bufstats(void) 3576 { 3577 int i, j, count; 3578 struct buf *bp; 3579 struct bqueues *dp; 3580 int counts[(MAXBSIZE / PAGE_SIZE) + 1]; 3581 static char *bname[3] = { "LOCKED", "LRU", "AGE" }; 3582 3583 for (dp = bufqueues, i = 0; dp < &bufqueues[3]; dp++, i++) { 3584 count = 0; 3585 for (j = 0; j <= MAXBSIZE/PAGE_SIZE; j++) 3586 counts[j] = 0; 3587 crit_enter(); 3588 TAILQ_FOREACH(bp, dp, b_freelist) { 3589 counts[bp->b_bufsize/PAGE_SIZE]++; 3590 count++; 3591 } 3592 crit_exit(); 3593 kprintf("%s: total-%d", bname[i], count); 3594 for (j = 0; j <= MAXBSIZE/PAGE_SIZE; j++) 3595 if (counts[j] != 0) 3596 kprintf(", %d-%d", j * PAGE_SIZE, counts[j]); 3597 kprintf("\n"); 3598 } 3599 } 3600 #endif 3601 3602 #ifdef DDB 3603 3604 DB_SHOW_COMMAND(buffer, db_show_buffer) 3605 { 3606 /* get args */ 3607 struct buf *bp = (struct buf *)addr; 3608 3609 if (!have_addr) { 3610 db_printf("usage: show buffer <addr>\n"); 3611 return; 3612 } 3613 3614 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS); 3615 db_printf("b_cmd = %d\n", bp->b_cmd); 3616 db_printf("b_error = %d, b_bufsize = %d, b_bcount = %d, " 3617 "b_resid = %d\n, b_data = %p, " 3618 "bio_offset(disk) = %lld, bio_offset(phys) = %lld\n", 3619 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 3620 bp->b_data, bp->b_bio2.bio_offset, (bp->b_bio2.bio_next ? bp->b_bio2.bio_next->bio_offset : (off_t)-1)); 3621 if (bp->b_xio.xio_npages) { 3622 int i; 3623 db_printf("b_xio.xio_npages = %d, pages(OBJ, IDX, PA): ", 3624 bp->b_xio.xio_npages); 3625 for (i = 0; i < bp->b_xio.xio_npages; i++) { 3626 vm_page_t m; 3627 m = bp->b_xio.xio_pages[i]; 3628 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 3629 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 3630 if ((i + 1) < bp->b_xio.xio_npages) 3631 db_printf(","); 3632 } 3633 db_printf("\n"); 3634 } 3635 } 3636 #endif /* DDB */ 3637