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 1.89 2007/01/12 03:05:49 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 bio_ops bioops; /* I/O operation notification */ 84 85 struct buf *buf; /* buffer header pool */ 86 87 static void vm_hold_free_pages(struct buf *bp, vm_offset_t from, 88 vm_offset_t to); 89 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from, 90 vm_offset_t to); 91 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, 92 int pageno, vm_page_t m); 93 static void vfs_clean_pages(struct buf *bp); 94 static void vfs_setdirty(struct buf *bp); 95 static void vfs_vmio_release(struct buf *bp); 96 static int flushbufqueues(void); 97 98 static void buf_daemon (void); 99 /* 100 * bogus page -- for I/O to/from partially complete buffers 101 * this is a temporary solution to the problem, but it is not 102 * really that bad. it would be better to split the buffer 103 * for input in the case of buffers partially already in memory, 104 * but the code is intricate enough already. 105 */ 106 vm_page_t bogus_page; 107 int runningbufspace; 108 109 /* 110 * These are all static, but make the ones we export globals so we do 111 * not need to use compiler magic. 112 */ 113 int bufspace, maxbufspace, 114 bufmallocspace, maxbufmallocspace, lobufspace, hibufspace; 115 static int bufreusecnt, bufdefragcnt, buffreekvacnt; 116 static int lorunningspace, hirunningspace, runningbufreq; 117 int numdirtybuffers, lodirtybuffers, hidirtybuffers; 118 static int numfreebuffers, lofreebuffers, hifreebuffers; 119 static int getnewbufcalls; 120 static int getnewbufrestarts; 121 122 static int needsbuffer; /* locked by needsbuffer_spin */ 123 static int bd_request; /* locked by needsbuffer_spin */ 124 static struct spinlock needsbuffer_spin; 125 126 /* 127 * Sysctls for operational control of the buffer cache. 128 */ 129 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0, 130 "Number of dirty buffers to flush before bufdaemon becomes inactive"); 131 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0, 132 "High watermark used to trigger explicit flushing of dirty buffers"); 133 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0, 134 "Low watermark for special reserve in low-memory situations"); 135 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0, 136 "High watermark for special reserve in low-memory situations"); 137 SYSCTL_INT(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0, 138 "Minimum amount of buffer space required for active I/O"); 139 SYSCTL_INT(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0, 140 "Maximum amount of buffer space to usable for active I/O"); 141 /* 142 * Sysctls determining current state of the buffer cache. 143 */ 144 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0, 145 "Pending number of dirty buffers"); 146 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, 147 "Number of free buffers on the buffer cache free list"); 148 SYSCTL_INT(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 149 "I/O bytes currently in progress due to asynchronous writes"); 150 SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0, 151 "Hard limit on maximum amount of memory usable for buffer space"); 152 SYSCTL_INT(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0, 153 "Soft limit on maximum amount of memory usable for buffer space"); 154 SYSCTL_INT(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0, 155 "Minimum amount of memory to reserve for system buffer space"); 156 SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, 157 "Amount of memory available for buffers"); 158 SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RD, &maxbufmallocspace, 159 0, "Maximum amount of memory reserved for buffers using malloc"); 160 SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 161 "Amount of memory left for buffers using malloc-scheme"); 162 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RD, &getnewbufcalls, 0, 163 "New buffer header acquisition requests"); 164 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RD, &getnewbufrestarts, 165 0, "New buffer header acquisition restarts"); 166 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RD, &bufdefragcnt, 0, 167 "Buffer acquisition restarts due to fragmented buffer map"); 168 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RD, &buffreekvacnt, 0, 169 "Amount of time KVA space was deallocated in an arbitrary buffer"); 170 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RD, &bufreusecnt, 0, 171 "Amount of time buffer re-use operations were successful"); 172 SYSCTL_INT(_debug_sizeof, OID_AUTO, buf, CTLFLAG_RD, 0, sizeof(struct buf), 173 "sizeof(struct buf)"); 174 175 char *buf_wmesg = BUF_WMESG; 176 177 extern int vm_swap_size; 178 179 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 180 #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */ 181 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ 182 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 183 184 /* 185 * numdirtywakeup: 186 * 187 * If someone is blocked due to there being too many dirty buffers, 188 * and numdirtybuffers is now reasonable, wake them up. 189 */ 190 191 static __inline void 192 numdirtywakeup(int level) 193 { 194 if (numdirtybuffers <= level) { 195 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) { 196 spin_lock_wr(&needsbuffer_spin); 197 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH; 198 spin_unlock_wr(&needsbuffer_spin); 199 wakeup(&needsbuffer); 200 } 201 } 202 } 203 204 /* 205 * bufspacewakeup: 206 * 207 * Called when buffer space is potentially available for recovery. 208 * getnewbuf() will block on this flag when it is unable to free 209 * sufficient buffer space. Buffer space becomes recoverable when 210 * bp's get placed back in the queues. 211 */ 212 213 static __inline void 214 bufspacewakeup(void) 215 { 216 /* 217 * If someone is waiting for BUF space, wake them up. Even 218 * though we haven't freed the kva space yet, the waiting 219 * process will be able to now. 220 */ 221 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) { 222 spin_lock_wr(&needsbuffer_spin); 223 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE; 224 spin_unlock_wr(&needsbuffer_spin); 225 wakeup(&needsbuffer); 226 } 227 } 228 229 /* 230 * runningbufwakeup: 231 * 232 * Accounting for I/O in progress. 233 * 234 */ 235 static __inline void 236 runningbufwakeup(struct buf *bp) 237 { 238 if (bp->b_runningbufspace) { 239 runningbufspace -= bp->b_runningbufspace; 240 bp->b_runningbufspace = 0; 241 if (runningbufreq && runningbufspace <= lorunningspace) { 242 runningbufreq = 0; 243 wakeup(&runningbufreq); 244 } 245 } 246 } 247 248 /* 249 * bufcountwakeup: 250 * 251 * Called when a buffer has been added to one of the free queues to 252 * account for the buffer and to wakeup anyone waiting for free buffers. 253 * This typically occurs when large amounts of metadata are being handled 254 * by the buffer cache ( else buffer space runs out first, usually ). 255 */ 256 257 static __inline void 258 bufcountwakeup(void) 259 { 260 ++numfreebuffers; 261 if (needsbuffer) { 262 spin_lock_wr(&needsbuffer_spin); 263 needsbuffer &= ~VFS_BIO_NEED_ANY; 264 if (numfreebuffers >= hifreebuffers) 265 needsbuffer &= ~VFS_BIO_NEED_FREE; 266 spin_unlock_wr(&needsbuffer_spin); 267 wakeup(&needsbuffer); 268 } 269 } 270 271 /* 272 * waitrunningbufspace() 273 * 274 * runningbufspace is a measure of the amount of I/O currently 275 * running. This routine is used in async-write situations to 276 * prevent creating huge backups of pending writes to a device. 277 * Only asynchronous writes are governed by this function. 278 * 279 * Reads will adjust runningbufspace, but will not block based on it. 280 * The read load has a side effect of reducing the allowed write load. 281 * 282 * This does NOT turn an async write into a sync write. It waits 283 * for earlier writes to complete and generally returns before the 284 * caller's write has reached the device. 285 */ 286 static __inline void 287 waitrunningbufspace(void) 288 { 289 if (runningbufspace > hirunningspace) { 290 crit_enter(); 291 while (runningbufspace > hirunningspace) { 292 ++runningbufreq; 293 tsleep(&runningbufreq, 0, "wdrain", 0); 294 } 295 crit_exit(); 296 } 297 } 298 299 /* 300 * vfs_buf_test_cache: 301 * 302 * Called when a buffer is extended. This function clears the B_CACHE 303 * bit if the newly extended portion of the buffer does not contain 304 * valid data. 305 */ 306 static __inline__ 307 void 308 vfs_buf_test_cache(struct buf *bp, 309 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 310 vm_page_t m) 311 { 312 if (bp->b_flags & B_CACHE) { 313 int base = (foff + off) & PAGE_MASK; 314 if (vm_page_is_valid(m, base, size) == 0) 315 bp->b_flags &= ~B_CACHE; 316 } 317 } 318 319 /* 320 * bd_wakeup: 321 * 322 * Wake up the buffer daemon if the number of outstanding dirty buffers 323 * is above specified threshold 'dirtybuflevel'. 324 * 325 * The buffer daemon is explicitly woken up when (a) the pending number 326 * of dirty buffers exceeds the recovery and stall mid-point value, 327 * (b) during bwillwrite() or (c) buf freelist was exhausted. 328 */ 329 static __inline__ 330 void 331 bd_wakeup(int dirtybuflevel) 332 { 333 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) { 334 spin_lock_wr(&needsbuffer_spin); 335 bd_request = 1; 336 spin_unlock_wr(&needsbuffer_spin); 337 wakeup(&bd_request); 338 } 339 } 340 341 /* 342 * bd_speedup: 343 * 344 * Speed up the buffer cache flushing process. 345 */ 346 347 static __inline__ 348 void 349 bd_speedup(void) 350 { 351 bd_wakeup(1); 352 } 353 354 /* 355 * bufinit: 356 * 357 * Load time initialisation of the buffer cache, called from machine 358 * dependant initialization code. 359 */ 360 void 361 bufinit(void) 362 { 363 struct buf *bp; 364 vm_offset_t bogus_offset; 365 int i; 366 367 spin_init(&needsbuffer_spin); 368 369 /* next, make a null set of free lists */ 370 for (i = 0; i < BUFFER_QUEUES; i++) 371 TAILQ_INIT(&bufqueues[i]); 372 373 /* finally, initialize each buffer header and stick on empty q */ 374 for (i = 0; i < nbuf; i++) { 375 bp = &buf[i]; 376 bzero(bp, sizeof *bp); 377 bp->b_flags = B_INVAL; /* we're just an empty header */ 378 bp->b_cmd = BUF_CMD_DONE; 379 bp->b_qindex = BQUEUE_EMPTY; 380 initbufbio(bp); 381 xio_init(&bp->b_xio); 382 LIST_INIT(&bp->b_dep); 383 BUF_LOCKINIT(bp); 384 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_EMPTY], bp, b_freelist); 385 } 386 387 /* 388 * maxbufspace is the absolute maximum amount of buffer space we are 389 * allowed to reserve in KVM and in real terms. The absolute maximum 390 * is nominally used by buf_daemon. hibufspace is the nominal maximum 391 * used by most other processes. The differential is required to 392 * ensure that buf_daemon is able to run when other processes might 393 * be blocked waiting for buffer space. 394 * 395 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 396 * this may result in KVM fragmentation which is not handled optimally 397 * by the system. 398 */ 399 maxbufspace = nbuf * BKVASIZE; 400 hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 401 lobufspace = hibufspace - MAXBSIZE; 402 403 lorunningspace = 512 * 1024; 404 hirunningspace = 1024 * 1024; 405 406 /* 407 * Limit the amount of malloc memory since it is wired permanently into 408 * the kernel space. Even though this is accounted for in the buffer 409 * allocation, we don't want the malloced region to grow uncontrolled. 410 * The malloc scheme improves memory utilization significantly on average 411 * (small) directories. 412 */ 413 maxbufmallocspace = hibufspace / 20; 414 415 /* 416 * Reduce the chance of a deadlock occuring by limiting the number 417 * of delayed-write dirty buffers we allow to stack up. 418 */ 419 hidirtybuffers = nbuf / 4 + 20; 420 numdirtybuffers = 0; 421 /* 422 * To support extreme low-memory systems, make sure hidirtybuffers cannot 423 * eat up all available buffer space. This occurs when our minimum cannot 424 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 425 * BKVASIZE'd (8K) buffers. 426 */ 427 while (hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 428 hidirtybuffers >>= 1; 429 } 430 lodirtybuffers = hidirtybuffers / 2; 431 432 /* 433 * Try to keep the number of free buffers in the specified range, 434 * and give special processes (e.g. like buf_daemon) access to an 435 * emergency reserve. 436 */ 437 lofreebuffers = nbuf / 18 + 5; 438 hifreebuffers = 2 * lofreebuffers; 439 numfreebuffers = nbuf; 440 441 /* 442 * Maximum number of async ops initiated per buf_daemon loop. This is 443 * somewhat of a hack at the moment, we really need to limit ourselves 444 * based on the number of bytes of I/O in-transit that were initiated 445 * from buf_daemon. 446 */ 447 448 bogus_offset = kmem_alloc_pageable(&kernel_map, PAGE_SIZE); 449 bogus_page = vm_page_alloc(&kernel_object, 450 (bogus_offset >> PAGE_SHIFT), 451 VM_ALLOC_NORMAL); 452 vmstats.v_wire_count++; 453 454 } 455 456 /* 457 * Initialize the embedded bio structures 458 */ 459 void 460 initbufbio(struct buf *bp) 461 { 462 bp->b_bio1.bio_buf = bp; 463 bp->b_bio1.bio_prev = NULL; 464 bp->b_bio1.bio_offset = NOOFFSET; 465 bp->b_bio1.bio_next = &bp->b_bio2; 466 bp->b_bio1.bio_done = NULL; 467 468 bp->b_bio2.bio_buf = bp; 469 bp->b_bio2.bio_prev = &bp->b_bio1; 470 bp->b_bio2.bio_offset = NOOFFSET; 471 bp->b_bio2.bio_next = NULL; 472 bp->b_bio2.bio_done = NULL; 473 } 474 475 /* 476 * Reinitialize the embedded bio structures as well as any additional 477 * translation cache layers. 478 */ 479 void 480 reinitbufbio(struct buf *bp) 481 { 482 struct bio *bio; 483 484 for (bio = &bp->b_bio1; bio; bio = bio->bio_next) { 485 bio->bio_done = NULL; 486 bio->bio_offset = NOOFFSET; 487 } 488 } 489 490 /* 491 * Push another BIO layer onto an existing BIO and return it. The new 492 * BIO layer may already exist, holding cached translation data. 493 */ 494 struct bio * 495 push_bio(struct bio *bio) 496 { 497 struct bio *nbio; 498 499 if ((nbio = bio->bio_next) == NULL) { 500 int index = bio - &bio->bio_buf->b_bio_array[0]; 501 if (index >= NBUF_BIO - 1) { 502 panic("push_bio: too many layers bp %p\n", 503 bio->bio_buf); 504 } 505 nbio = &bio->bio_buf->b_bio_array[index + 1]; 506 bio->bio_next = nbio; 507 nbio->bio_prev = bio; 508 nbio->bio_buf = bio->bio_buf; 509 nbio->bio_offset = NOOFFSET; 510 nbio->bio_done = NULL; 511 nbio->bio_next = NULL; 512 } 513 KKASSERT(nbio->bio_done == NULL); 514 return(nbio); 515 } 516 517 void 518 pop_bio(struct bio *bio) 519 { 520 /* NOP */ 521 } 522 523 void 524 clearbiocache(struct bio *bio) 525 { 526 while (bio) { 527 bio->bio_offset = NOOFFSET; 528 bio = bio->bio_next; 529 } 530 } 531 532 /* 533 * bfreekva: 534 * 535 * Free the KVA allocation for buffer 'bp'. 536 * 537 * Must be called from a critical section as this is the only locking for 538 * buffer_map. 539 * 540 * Since this call frees up buffer space, we call bufspacewakeup(). 541 */ 542 static void 543 bfreekva(struct buf *bp) 544 { 545 int count; 546 547 if (bp->b_kvasize) { 548 ++buffreekvacnt; 549 count = vm_map_entry_reserve(MAP_RESERVE_COUNT); 550 vm_map_lock(&buffer_map); 551 bufspace -= bp->b_kvasize; 552 vm_map_delete(&buffer_map, 553 (vm_offset_t) bp->b_kvabase, 554 (vm_offset_t) bp->b_kvabase + bp->b_kvasize, 555 &count 556 ); 557 vm_map_unlock(&buffer_map); 558 vm_map_entry_release(count); 559 bp->b_kvasize = 0; 560 bufspacewakeup(); 561 } 562 } 563 564 /* 565 * bremfree: 566 * 567 * Remove the buffer from the appropriate free list. 568 */ 569 void 570 bremfree(struct buf *bp) 571 { 572 int old_qindex; 573 574 crit_enter(); 575 old_qindex = bp->b_qindex; 576 577 if (bp->b_qindex != BQUEUE_NONE) { 578 KASSERT(BUF_REFCNTNB(bp) == 1, 579 ("bremfree: bp %p not locked",bp)); 580 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 581 bp->b_qindex = BQUEUE_NONE; 582 } else { 583 if (BUF_REFCNTNB(bp) <= 1) 584 panic("bremfree: removing a buffer not on a queue"); 585 } 586 587 /* 588 * Fixup numfreebuffers count. If the buffer is invalid or not 589 * delayed-write, and it was on the EMPTY, LRU, or AGE queues, 590 * the buffer was free and we must decrement numfreebuffers. 591 */ 592 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { 593 switch(old_qindex) { 594 case BQUEUE_DIRTY: 595 case BQUEUE_CLEAN: 596 case BQUEUE_EMPTY: 597 case BQUEUE_EMPTYKVA: 598 --numfreebuffers; 599 break; 600 default: 601 break; 602 } 603 } 604 crit_exit(); 605 } 606 607 608 /* 609 * bread: 610 * 611 * Get a buffer with the specified data. Look in the cache first. We 612 * must clear B_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 613 * is set, the buffer is valid and we do not have to do anything ( see 614 * getblk() ). 615 */ 616 int 617 bread(struct vnode *vp, off_t loffset, int size, struct buf **bpp) 618 { 619 struct buf *bp; 620 621 bp = getblk(vp, loffset, size, 0, 0); 622 *bpp = bp; 623 624 /* if not found in cache, do some I/O */ 625 if ((bp->b_flags & B_CACHE) == 0) { 626 KASSERT(!(bp->b_flags & B_ASYNC), ("bread: illegal async bp %p", bp)); 627 bp->b_flags &= ~(B_ERROR | B_INVAL); 628 bp->b_cmd = BUF_CMD_READ; 629 vfs_busy_pages(vp, bp); 630 vn_strategy(vp, &bp->b_bio1); 631 return (biowait(bp)); 632 } 633 return (0); 634 } 635 636 /* 637 * breadn: 638 * 639 * Operates like bread, but also starts asynchronous I/O on 640 * read-ahead blocks. We must clear B_ERROR and B_INVAL prior 641 * to initiating I/O . If B_CACHE is set, the buffer is valid 642 * and we do not have to do anything. 643 */ 644 int 645 breadn(struct vnode *vp, off_t loffset, int size, off_t *raoffset, 646 int *rabsize, int cnt, struct buf **bpp) 647 { 648 struct buf *bp, *rabp; 649 int i; 650 int rv = 0, readwait = 0; 651 652 *bpp = bp = getblk(vp, loffset, size, 0, 0); 653 654 /* if not found in cache, do some I/O */ 655 if ((bp->b_flags & B_CACHE) == 0) { 656 bp->b_flags &= ~(B_ERROR | B_INVAL); 657 bp->b_cmd = BUF_CMD_READ; 658 vfs_busy_pages(vp, bp); 659 vn_strategy(vp, &bp->b_bio1); 660 ++readwait; 661 } 662 663 for (i = 0; i < cnt; i++, raoffset++, rabsize++) { 664 if (inmem(vp, *raoffset)) 665 continue; 666 rabp = getblk(vp, *raoffset, *rabsize, 0, 0); 667 668 if ((rabp->b_flags & B_CACHE) == 0) { 669 rabp->b_flags |= B_ASYNC; 670 rabp->b_flags &= ~(B_ERROR | B_INVAL); 671 rabp->b_cmd = BUF_CMD_READ; 672 vfs_busy_pages(vp, rabp); 673 BUF_KERNPROC(rabp); 674 vn_strategy(vp, &rabp->b_bio1); 675 } else { 676 brelse(rabp); 677 } 678 } 679 680 if (readwait) { 681 rv = biowait(bp); 682 } 683 return (rv); 684 } 685 686 /* 687 * bwrite: 688 * 689 * Write, release buffer on completion. (Done by iodone 690 * if async). Do not bother writing anything if the buffer 691 * is invalid. 692 * 693 * Note that we set B_CACHE here, indicating that buffer is 694 * fully valid and thus cacheable. This is true even of NFS 695 * now so we set it generally. This could be set either here 696 * or in biodone() since the I/O is synchronous. We put it 697 * here. 698 */ 699 int 700 bwrite(struct buf *bp) 701 { 702 int oldflags; 703 704 if (bp->b_flags & B_INVAL) { 705 brelse(bp); 706 return (0); 707 } 708 709 oldflags = bp->b_flags; 710 711 if (BUF_REFCNTNB(bp) == 0) 712 panic("bwrite: buffer is not busy???"); 713 crit_enter(); 714 715 /* Mark the buffer clean */ 716 bundirty(bp); 717 718 bp->b_flags &= ~B_ERROR; 719 bp->b_flags |= B_CACHE; 720 bp->b_cmd = BUF_CMD_WRITE; 721 vfs_busy_pages(bp->b_vp, bp); 722 723 /* 724 * Normal bwrites pipeline writes. NOTE: b_bufsize is only 725 * valid for vnode-backed buffers. 726 */ 727 bp->b_runningbufspace = bp->b_bufsize; 728 runningbufspace += bp->b_runningbufspace; 729 730 crit_exit(); 731 if (oldflags & B_ASYNC) 732 BUF_KERNPROC(bp); 733 vn_strategy(bp->b_vp, &bp->b_bio1); 734 735 if ((oldflags & B_ASYNC) == 0) { 736 int rtval = biowait(bp); 737 brelse(bp); 738 return (rtval); 739 } else if ((oldflags & B_NOWDRAIN) == 0) { 740 /* 741 * don't allow the async write to saturate the I/O 742 * system. Deadlocks can occur only if a device strategy 743 * routine (like in VN) turns around and issues another 744 * high-level write, in which case B_NOWDRAIN is expected 745 * to be set. Otherwise we will not deadlock here because 746 * we are blocking waiting for I/O that is already in-progress 747 * to complete. 748 */ 749 waitrunningbufspace(); 750 } 751 752 return (0); 753 } 754 755 /* 756 * bdwrite: 757 * 758 * Delayed write. (Buffer is marked dirty). Do not bother writing 759 * anything if the buffer is marked invalid. 760 * 761 * Note that since the buffer must be completely valid, we can safely 762 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 763 * biodone() in order to prevent getblk from writing the buffer 764 * out synchronously. 765 */ 766 void 767 bdwrite(struct buf *bp) 768 { 769 if (BUF_REFCNTNB(bp) == 0) 770 panic("bdwrite: buffer is not busy"); 771 772 if (bp->b_flags & B_INVAL) { 773 brelse(bp); 774 return; 775 } 776 bdirty(bp); 777 778 /* 779 * Set B_CACHE, indicating that the buffer is fully valid. This is 780 * true even of NFS now. 781 */ 782 bp->b_flags |= B_CACHE; 783 784 /* 785 * This bmap keeps the system from needing to do the bmap later, 786 * perhaps when the system is attempting to do a sync. Since it 787 * is likely that the indirect block -- or whatever other datastructure 788 * that the filesystem needs is still in memory now, it is a good 789 * thing to do this. Note also, that if the pageout daemon is 790 * requesting a sync -- there might not be enough memory to do 791 * the bmap then... So, this is important to do. 792 */ 793 if (bp->b_bio2.bio_offset == NOOFFSET) { 794 VOP_BMAP(bp->b_vp, bp->b_loffset, NULL, &bp->b_bio2.bio_offset, 795 NULL, NULL); 796 } 797 798 /* 799 * Set the *dirty* buffer range based upon the VM system dirty pages. 800 */ 801 vfs_setdirty(bp); 802 803 /* 804 * We need to do this here to satisfy the vnode_pager and the 805 * pageout daemon, so that it thinks that the pages have been 806 * "cleaned". Note that since the pages are in a delayed write 807 * buffer -- the VFS layer "will" see that the pages get written 808 * out on the next sync, or perhaps the cluster will be completed. 809 */ 810 vfs_clean_pages(bp); 811 bqrelse(bp); 812 813 /* 814 * Wakeup the buffer flushing daemon if we have a lot of dirty 815 * buffers (midpoint between our recovery point and our stall 816 * point). 817 */ 818 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 819 820 /* 821 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 822 * due to the softdep code. 823 */ 824 } 825 826 /* 827 * bdirty: 828 * 829 * Turn buffer into delayed write request by marking it B_DELWRI. 830 * B_RELBUF and B_NOCACHE must be cleared. 831 * 832 * We reassign the buffer to itself to properly update it in the 833 * dirty/clean lists. 834 * 835 * Since the buffer is not on a queue, we do not update the 836 * numfreebuffers count. 837 * 838 * Must be called from a critical section. 839 * The buffer must be on BQUEUE_NONE. 840 */ 841 void 842 bdirty(struct buf *bp) 843 { 844 KASSERT(bp->b_qindex == BQUEUE_NONE, ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 845 if (bp->b_flags & B_NOCACHE) { 846 kprintf("bdirty: clearing B_NOCACHE on buf %p\n", bp); 847 bp->b_flags &= ~B_NOCACHE; 848 } 849 if (bp->b_flags & B_INVAL) { 850 kprintf("bdirty: warning, dirtying invalid buffer %p\n", bp); 851 } 852 bp->b_flags &= ~B_RELBUF; 853 854 if ((bp->b_flags & B_DELWRI) == 0) { 855 bp->b_flags |= B_DELWRI; 856 reassignbuf(bp); 857 ++numdirtybuffers; 858 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 859 } 860 } 861 862 /* 863 * bundirty: 864 * 865 * Clear B_DELWRI for buffer. 866 * 867 * Since the buffer is not on a queue, we do not update the numfreebuffers 868 * count. 869 * 870 * Must be called from a critical section. 871 * 872 * The buffer is typically on BQUEUE_NONE but there is one case in 873 * brelse() that calls this function after placing the buffer on 874 * a different queue. 875 */ 876 877 void 878 bundirty(struct buf *bp) 879 { 880 if (bp->b_flags & B_DELWRI) { 881 bp->b_flags &= ~B_DELWRI; 882 reassignbuf(bp); 883 --numdirtybuffers; 884 numdirtywakeup(lodirtybuffers); 885 } 886 /* 887 * Since it is now being written, we can clear its deferred write flag. 888 */ 889 bp->b_flags &= ~B_DEFERRED; 890 } 891 892 /* 893 * bawrite: 894 * 895 * Asynchronous write. Start output on a buffer, but do not wait for 896 * it to complete. The buffer is released when the output completes. 897 * 898 * bwrite() ( or the VOP routine anyway ) is responsible for handling 899 * B_INVAL buffers. Not us. 900 */ 901 void 902 bawrite(struct buf *bp) 903 { 904 bp->b_flags |= B_ASYNC; 905 bwrite(bp); 906 } 907 908 /* 909 * bowrite: 910 * 911 * Ordered write. Start output on a buffer, and flag it so that the 912 * device will write it in the order it was queued. The buffer is 913 * released when the output completes. bwrite() ( or the VOP routine 914 * anyway ) is responsible for handling B_INVAL buffers. 915 */ 916 int 917 bowrite(struct buf *bp) 918 { 919 bp->b_flags |= B_ORDERED | B_ASYNC; 920 return (bwrite(bp)); 921 } 922 923 /* 924 * bwillwrite: 925 * 926 * Called prior to the locking of any vnodes when we are expecting to 927 * write. We do not want to starve the buffer cache with too many 928 * dirty buffers so we block here. By blocking prior to the locking 929 * of any vnodes we attempt to avoid the situation where a locked vnode 930 * prevents the various system daemons from flushing related buffers. 931 */ 932 933 void 934 bwillwrite(void) 935 { 936 if (numdirtybuffers >= hidirtybuffers) { 937 while (numdirtybuffers >= hidirtybuffers) { 938 bd_wakeup(1); 939 spin_lock_wr(&needsbuffer_spin); 940 if (numdirtybuffers >= hidirtybuffers) { 941 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH; 942 msleep(&needsbuffer, &needsbuffer_spin, 0, 943 "flswai", 0); 944 } 945 spin_unlock_wr(&needsbuffer_spin); 946 } 947 } 948 } 949 950 /* 951 * buf_dirty_count_severe: 952 * 953 * Return true if we have too many dirty buffers. 954 */ 955 int 956 buf_dirty_count_severe(void) 957 { 958 return(numdirtybuffers >= hidirtybuffers); 959 } 960 961 /* 962 * brelse: 963 * 964 * Release a busy buffer and, if requested, free its resources. The 965 * buffer will be stashed in the appropriate bufqueue[] allowing it 966 * to be accessed later as a cache entity or reused for other purposes. 967 */ 968 void 969 brelse(struct buf *bp) 970 { 971 #ifdef INVARIANTS 972 int saved_flags = bp->b_flags; 973 #endif 974 975 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 976 977 crit_enter(); 978 979 /* 980 * If B_NOCACHE is set we are being asked to destroy the buffer and 981 * its backing store. Clear B_DELWRI. 982 * 983 * B_NOCACHE is set in two cases: (1) when the caller really wants 984 * to destroy the buffer and backing store and (2) when the caller 985 * wants to destroy the buffer and backing store after a write 986 * completes. 987 */ 988 if ((bp->b_flags & (B_NOCACHE|B_DELWRI)) == (B_NOCACHE|B_DELWRI)) { 989 bundirty(bp); 990 } 991 992 if (bp->b_flags & B_LOCKED) 993 bp->b_flags &= ~B_ERROR; 994 995 /* 996 * If a write error occurs and the caller does not want to throw 997 * away the buffer, redirty the buffer. This will also clear 998 * B_NOCACHE. 999 */ 1000 if (bp->b_cmd == BUF_CMD_WRITE && 1001 (bp->b_flags & (B_ERROR | B_INVAL)) == B_ERROR) { 1002 /* 1003 * Failed write, redirty. Must clear B_ERROR to prevent 1004 * pages from being scrapped. If B_INVAL is set then 1005 * this case is not run and the next case is run to 1006 * destroy the buffer. B_INVAL can occur if the buffer 1007 * is outside the range supported by the underlying device. 1008 */ 1009 bp->b_flags &= ~B_ERROR; 1010 bdirty(bp); 1011 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR)) || 1012 (bp->b_bufsize <= 0) || bp->b_cmd == BUF_CMD_FREEBLKS) { 1013 /* 1014 * Either a failed I/O or we were asked to free or not 1015 * cache the buffer. 1016 */ 1017 bp->b_flags |= B_INVAL; 1018 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_deallocate) 1019 (*bioops.io_deallocate)(bp); 1020 if (bp->b_flags & B_DELWRI) { 1021 --numdirtybuffers; 1022 numdirtywakeup(lodirtybuffers); 1023 } 1024 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1025 } 1026 1027 /* 1028 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1029 * is called with B_DELWRI set, the underlying pages may wind up 1030 * getting freed causing a previous write (bdwrite()) to get 'lost' 1031 * because pages associated with a B_DELWRI bp are marked clean. 1032 * 1033 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1034 * if B_DELWRI is set. 1035 * 1036 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1037 * on pages to return pages to the VM page queues. 1038 */ 1039 if (bp->b_flags & B_DELWRI) 1040 bp->b_flags &= ~B_RELBUF; 1041 else if (vm_page_count_severe()) 1042 bp->b_flags |= B_RELBUF; 1043 1044 /* 1045 * At this point destroying the buffer is governed by the B_INVAL 1046 * or B_RELBUF flags. 1047 */ 1048 bp->b_cmd = BUF_CMD_DONE; 1049 1050 /* 1051 * VMIO buffer rundown. Make sure the VM page array is restored 1052 * after an I/O may have replaces some of the pages with bogus pages 1053 * in order to not destroy dirty pages in a fill-in read. 1054 * 1055 * Note that due to the code above, if a buffer is marked B_DELWRI 1056 * then the B_RELBUF and B_NOCACHE bits will always be clear. 1057 * B_INVAL may still be set, however. 1058 * 1059 * For clean buffers, B_INVAL or B_RELBUF will destroy the buffer 1060 * but not the backing store. B_NOCACHE will destroy the backing 1061 * store. 1062 * 1063 * Note that dirty NFS buffers contain byte-granular write ranges 1064 * and should not be destroyed w/ B_INVAL even if the backing store 1065 * is left intact. 1066 */ 1067 if (bp->b_flags & B_VMIO) { 1068 /* 1069 * Rundown for VMIO buffers which are not dirty NFS buffers. 1070 */ 1071 int i, j, resid; 1072 vm_page_t m; 1073 off_t foff; 1074 vm_pindex_t poff; 1075 vm_object_t obj; 1076 struct vnode *vp; 1077 1078 vp = bp->b_vp; 1079 1080 /* 1081 * Get the base offset and length of the buffer. Note that 1082 * in the VMIO case if the buffer block size is not 1083 * page-aligned then b_data pointer may not be page-aligned. 1084 * But our b_xio.xio_pages array *IS* page aligned. 1085 * 1086 * block sizes less then DEV_BSIZE (usually 512) are not 1087 * supported due to the page granularity bits (m->valid, 1088 * m->dirty, etc...). 1089 * 1090 * See man buf(9) for more information 1091 */ 1092 1093 resid = bp->b_bufsize; 1094 foff = bp->b_loffset; 1095 1096 for (i = 0; i < bp->b_xio.xio_npages; i++) { 1097 m = bp->b_xio.xio_pages[i]; 1098 vm_page_flag_clear(m, PG_ZERO); 1099 /* 1100 * If we hit a bogus page, fixup *all* of them 1101 * now. Note that we left these pages wired 1102 * when we removed them so they had better exist, 1103 * and they cannot be ripped out from under us so 1104 * no critical section protection is necessary. 1105 */ 1106 if (m == bogus_page) { 1107 obj = vp->v_object; 1108 poff = OFF_TO_IDX(bp->b_loffset); 1109 1110 for (j = i; j < bp->b_xio.xio_npages; j++) { 1111 vm_page_t mtmp; 1112 1113 mtmp = bp->b_xio.xio_pages[j]; 1114 if (mtmp == bogus_page) { 1115 mtmp = vm_page_lookup(obj, poff + j); 1116 if (!mtmp) { 1117 panic("brelse: page missing"); 1118 } 1119 bp->b_xio.xio_pages[j] = mtmp; 1120 } 1121 } 1122 1123 if ((bp->b_flags & B_INVAL) == 0) { 1124 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 1125 bp->b_xio.xio_pages, bp->b_xio.xio_npages); 1126 } 1127 m = bp->b_xio.xio_pages[i]; 1128 } 1129 1130 /* 1131 * Invalidate the backing store if B_NOCACHE is set 1132 * (e.g. used with vinvalbuf()). If this is NFS 1133 * we impose a requirement that the block size be 1134 * a multiple of PAGE_SIZE and create a temporary 1135 * hack to basically invalidate the whole page. The 1136 * problem is that NFS uses really odd buffer sizes 1137 * especially when tracking piecemeal writes and 1138 * it also vinvalbuf()'s a lot, which would result 1139 * in only partial page validation and invalidation 1140 * here. If the file page is mmap()'d, however, 1141 * all the valid bits get set so after we invalidate 1142 * here we would end up with weird m->valid values 1143 * like 0xfc. nfs_getpages() can't handle this so 1144 * we clear all the valid bits for the NFS case 1145 * instead of just some of them. 1146 * 1147 * The real bug is the VM system having to set m->valid 1148 * to VM_PAGE_BITS_ALL for faulted-in pages, which 1149 * itself is an artifact of the whole 512-byte 1150 * granular mess that exists to support odd block 1151 * sizes and UFS meta-data block sizes (e.g. 6144). 1152 * A complete rewrite is required. 1153 */ 1154 if (bp->b_flags & (B_NOCACHE|B_ERROR)) { 1155 int poffset = foff & PAGE_MASK; 1156 int presid; 1157 1158 presid = PAGE_SIZE - poffset; 1159 if (bp->b_vp->v_tag == VT_NFS && 1160 bp->b_vp->v_type == VREG) { 1161 ; /* entire page */ 1162 } else if (presid > resid) { 1163 presid = resid; 1164 } 1165 KASSERT(presid >= 0, ("brelse: extra page")); 1166 vm_page_set_invalid(m, poffset, presid); 1167 } 1168 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1169 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1170 } 1171 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1172 vfs_vmio_release(bp); 1173 } else { 1174 /* 1175 * Rundown for non-VMIO buffers. 1176 */ 1177 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1178 #if 0 1179 if (bp->b_vp) 1180 kprintf("brelse bp %p %08x/%08x: Warning, caught and fixed brelvp bug\n", bp, saved_flags, bp->b_flags); 1181 #endif 1182 if (bp->b_bufsize) 1183 allocbuf(bp, 0); 1184 if (bp->b_vp) 1185 brelvp(bp); 1186 } 1187 } 1188 1189 if (bp->b_qindex != BQUEUE_NONE) 1190 panic("brelse: free buffer onto another queue???"); 1191 if (BUF_REFCNTNB(bp) > 1) { 1192 /* Temporary panic to verify exclusive locking */ 1193 /* This panic goes away when we allow shared refs */ 1194 panic("brelse: multiple refs"); 1195 /* do not release to free list */ 1196 BUF_UNLOCK(bp); 1197 crit_exit(); 1198 return; 1199 } 1200 1201 /* 1202 * Figure out the correct queue to place the cleaned up buffer on. 1203 * Buffers placed in the EMPTY or EMPTYKVA had better already be 1204 * disassociated from their vnode. 1205 */ 1206 1207 if (bp->b_bufsize == 0) { 1208 /* 1209 * Buffers with no memory. Due to conditionals near the top 1210 * of brelse() such buffers should probably already be 1211 * marked B_INVAL and disassociated from their vnode. 1212 */ 1213 bp->b_flags |= B_INVAL; 1214 KASSERT(bp->b_vp == NULL, ("bp1 %p flags %08x/%08x vnode %p unexpectededly still associated!", bp, saved_flags, bp->b_flags, bp->b_vp)); 1215 KKASSERT((bp->b_flags & B_HASHED) == 0); 1216 if (bp->b_kvasize) { 1217 bp->b_qindex = BQUEUE_EMPTYKVA; 1218 } else { 1219 bp->b_qindex = BQUEUE_EMPTY; 1220 } 1221 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1222 } else if (bp->b_flags & (B_ERROR | B_INVAL | B_NOCACHE | B_RELBUF)) { 1223 /* 1224 * Buffers with junk contents. Again these buffers had better 1225 * already be disassociated from their vnode. 1226 */ 1227 KASSERT(bp->b_vp == NULL, ("bp2 %p flags %08x/%08x vnode %p unexpectededly still associated!", bp, saved_flags, bp->b_flags, bp->b_vp)); 1228 KKASSERT((bp->b_flags & B_HASHED) == 0); 1229 bp->b_flags |= B_INVAL; 1230 bp->b_qindex = BQUEUE_CLEAN; 1231 TAILQ_INSERT_HEAD(&bufqueues[BQUEUE_CLEAN], bp, b_freelist); 1232 } else if (bp->b_flags & B_LOCKED) { 1233 /* 1234 * Buffers that are locked. 1235 */ 1236 bp->b_qindex = BQUEUE_LOCKED; 1237 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_LOCKED], bp, b_freelist); 1238 } else { 1239 /* 1240 * Remaining buffers. These buffers are still associated with 1241 * their vnode. 1242 */ 1243 switch(bp->b_flags & (B_DELWRI|B_AGE)) { 1244 case B_DELWRI | B_AGE: 1245 bp->b_qindex = BQUEUE_DIRTY; 1246 TAILQ_INSERT_HEAD(&bufqueues[BQUEUE_DIRTY], bp, b_freelist); 1247 break; 1248 case B_DELWRI: 1249 bp->b_qindex = BQUEUE_DIRTY; 1250 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_DIRTY], bp, b_freelist); 1251 break; 1252 case B_AGE: 1253 bp->b_qindex = BQUEUE_CLEAN; 1254 TAILQ_INSERT_HEAD(&bufqueues[BQUEUE_CLEAN], bp, b_freelist); 1255 break; 1256 default: 1257 bp->b_qindex = BQUEUE_CLEAN; 1258 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_CLEAN], bp, b_freelist); 1259 break; 1260 } 1261 } 1262 1263 /* 1264 * If B_INVAL, clear B_DELWRI. We've already placed the buffer 1265 * on the correct queue. 1266 */ 1267 if ((bp->b_flags & (B_INVAL|B_DELWRI)) == (B_INVAL|B_DELWRI)) 1268 bundirty(bp); 1269 1270 /* 1271 * Fixup numfreebuffers count. The bp is on an appropriate queue 1272 * unless locked. We then bump numfreebuffers if it is not B_DELWRI. 1273 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1274 * if B_INVAL is set ). 1275 */ 1276 if ((bp->b_flags & B_LOCKED) == 0 && !(bp->b_flags & B_DELWRI)) 1277 bufcountwakeup(); 1278 1279 /* 1280 * Something we can maybe free or reuse 1281 */ 1282 if (bp->b_bufsize || bp->b_kvasize) 1283 bufspacewakeup(); 1284 1285 /* 1286 * Clean up temporary flags and unlock the buffer. 1287 */ 1288 bp->b_flags &= ~(B_ORDERED | B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | 1289 B_DIRECT | B_NOWDRAIN); 1290 BUF_UNLOCK(bp); 1291 crit_exit(); 1292 } 1293 1294 /* 1295 * bqrelse: 1296 * 1297 * Release a buffer back to the appropriate queue but do not try to free 1298 * it. The buffer is expected to be used again soon. 1299 * 1300 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1301 * biodone() to requeue an async I/O on completion. It is also used when 1302 * known good buffers need to be requeued but we think we may need the data 1303 * again soon. 1304 * 1305 * XXX we should be able to leave the B_RELBUF hint set on completion. 1306 */ 1307 void 1308 bqrelse(struct buf *bp) 1309 { 1310 crit_enter(); 1311 1312 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1313 1314 if (bp->b_qindex != BQUEUE_NONE) 1315 panic("bqrelse: free buffer onto another queue???"); 1316 if (BUF_REFCNTNB(bp) > 1) { 1317 /* do not release to free list */ 1318 panic("bqrelse: multiple refs"); 1319 BUF_UNLOCK(bp); 1320 crit_exit(); 1321 return; 1322 } 1323 if (bp->b_flags & B_LOCKED) { 1324 bp->b_flags &= ~B_ERROR; 1325 bp->b_qindex = BQUEUE_LOCKED; 1326 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_LOCKED], bp, b_freelist); 1327 /* buffers with stale but valid contents */ 1328 } else if (bp->b_flags & B_DELWRI) { 1329 bp->b_qindex = BQUEUE_DIRTY; 1330 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_DIRTY], bp, b_freelist); 1331 } else if (vm_page_count_severe()) { 1332 /* 1333 * We are too low on memory, we have to try to free the 1334 * buffer (most importantly: the wired pages making up its 1335 * backing store) *now*. 1336 */ 1337 crit_exit(); 1338 brelse(bp); 1339 return; 1340 } else { 1341 bp->b_qindex = BQUEUE_CLEAN; 1342 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_CLEAN], bp, b_freelist); 1343 } 1344 1345 if ((bp->b_flags & B_LOCKED) == 0 && 1346 ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI))) { 1347 bufcountwakeup(); 1348 } 1349 1350 /* 1351 * Something we can maybe free or reuse. 1352 */ 1353 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1354 bufspacewakeup(); 1355 1356 /* 1357 * Final cleanup and unlock. Clear bits that are only used while a 1358 * buffer is actively locked. 1359 */ 1360 bp->b_flags &= ~(B_ORDERED | B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1361 BUF_UNLOCK(bp); 1362 crit_exit(); 1363 } 1364 1365 /* 1366 * vfs_vmio_release: 1367 * 1368 * Return backing pages held by the buffer 'bp' back to the VM system 1369 * if possible. The pages are freed if they are no longer valid or 1370 * attempt to free if it was used for direct I/O otherwise they are 1371 * sent to the page cache. 1372 * 1373 * Pages that were marked busy are left alone and skipped. 1374 * 1375 * The KVA mapping (b_data) for the underlying pages is removed by 1376 * this function. 1377 */ 1378 static void 1379 vfs_vmio_release(struct buf *bp) 1380 { 1381 int i; 1382 vm_page_t m; 1383 1384 crit_enter(); 1385 for (i = 0; i < bp->b_xio.xio_npages; i++) { 1386 m = bp->b_xio.xio_pages[i]; 1387 bp->b_xio.xio_pages[i] = NULL; 1388 /* 1389 * In order to keep page LRU ordering consistent, put 1390 * everything on the inactive queue. 1391 */ 1392 vm_page_unwire(m, 0); 1393 /* 1394 * We don't mess with busy pages, it is 1395 * the responsibility of the process that 1396 * busied the pages to deal with them. 1397 */ 1398 if ((m->flags & PG_BUSY) || (m->busy != 0)) 1399 continue; 1400 1401 if (m->wire_count == 0) { 1402 vm_page_flag_clear(m, PG_ZERO); 1403 /* 1404 * Might as well free the page if we can and it has 1405 * no valid data. We also free the page if the 1406 * buffer was used for direct I/O. 1407 */ 1408 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && 1409 m->hold_count == 0) { 1410 vm_page_busy(m); 1411 vm_page_protect(m, VM_PROT_NONE); 1412 vm_page_free(m); 1413 } else if (bp->b_flags & B_DIRECT) { 1414 vm_page_try_to_free(m); 1415 } else if (vm_page_count_severe()) { 1416 vm_page_try_to_cache(m); 1417 } 1418 } 1419 } 1420 crit_exit(); 1421 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_xio.xio_npages); 1422 if (bp->b_bufsize) { 1423 bufspacewakeup(); 1424 bp->b_bufsize = 0; 1425 } 1426 bp->b_xio.xio_npages = 0; 1427 bp->b_flags &= ~B_VMIO; 1428 if (bp->b_vp) 1429 brelvp(bp); 1430 } 1431 1432 /* 1433 * vfs_bio_awrite: 1434 * 1435 * Implement clustered async writes for clearing out B_DELWRI buffers. 1436 * This is much better then the old way of writing only one buffer at 1437 * a time. Note that we may not be presented with the buffers in the 1438 * correct order, so we search for the cluster in both directions. 1439 * 1440 * The buffer is locked on call. 1441 */ 1442 int 1443 vfs_bio_awrite(struct buf *bp) 1444 { 1445 int i; 1446 int j; 1447 off_t loffset = bp->b_loffset; 1448 struct vnode *vp = bp->b_vp; 1449 int nbytes; 1450 struct buf *bpa; 1451 int nwritten; 1452 int size; 1453 1454 crit_enter(); 1455 /* 1456 * right now we support clustered writing only to regular files. If 1457 * we find a clusterable block we could be in the middle of a cluster 1458 * rather then at the beginning. 1459 * 1460 * NOTE: b_bio1 contains the logical loffset and is aliased 1461 * to b_loffset. b_bio2 contains the translated block number. 1462 */ 1463 if ((vp->v_type == VREG) && 1464 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1465 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1466 1467 size = vp->v_mount->mnt_stat.f_iosize; 1468 1469 for (i = size; i < MAXPHYS; i += size) { 1470 if ((bpa = findblk(vp, loffset + i)) && 1471 BUF_REFCNT(bpa) == 0 && 1472 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == 1473 (B_DELWRI | B_CLUSTEROK)) && 1474 (bpa->b_bufsize == size)) { 1475 if ((bpa->b_bio2.bio_offset == NOOFFSET) || 1476 (bpa->b_bio2.bio_offset != 1477 bp->b_bio2.bio_offset + i)) 1478 break; 1479 } else { 1480 break; 1481 } 1482 } 1483 for (j = size; i + j <= MAXPHYS && j <= loffset; j += size) { 1484 if ((bpa = findblk(vp, loffset - j)) && 1485 BUF_REFCNT(bpa) == 0 && 1486 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == 1487 (B_DELWRI | B_CLUSTEROK)) && 1488 (bpa->b_bufsize == size)) { 1489 if ((bpa->b_bio2.bio_offset == NOOFFSET) || 1490 (bpa->b_bio2.bio_offset != 1491 bp->b_bio2.bio_offset - j)) 1492 break; 1493 } else { 1494 break; 1495 } 1496 } 1497 j -= size; 1498 nbytes = (i + j); 1499 /* 1500 * this is a possible cluster write 1501 */ 1502 if (nbytes != size) { 1503 BUF_UNLOCK(bp); 1504 nwritten = cluster_wbuild(vp, size, 1505 loffset - j, nbytes); 1506 crit_exit(); 1507 return nwritten; 1508 } 1509 } 1510 1511 bremfree(bp); 1512 bp->b_flags |= B_ASYNC; 1513 1514 crit_exit(); 1515 /* 1516 * default (old) behavior, writing out only one block 1517 * 1518 * XXX returns b_bufsize instead of b_bcount for nwritten? 1519 */ 1520 nwritten = bp->b_bufsize; 1521 bwrite(bp); 1522 1523 return nwritten; 1524 } 1525 1526 /* 1527 * getnewbuf: 1528 * 1529 * Find and initialize a new buffer header, freeing up existing buffers 1530 * in the bufqueues as necessary. The new buffer is returned locked. 1531 * 1532 * Important: B_INVAL is not set. If the caller wishes to throw the 1533 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1534 * 1535 * We block if: 1536 * We have insufficient buffer headers 1537 * We have insufficient buffer space 1538 * buffer_map is too fragmented ( space reservation fails ) 1539 * If we have to flush dirty buffers ( but we try to avoid this ) 1540 * 1541 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1542 * Instead we ask the buf daemon to do it for us. We attempt to 1543 * avoid piecemeal wakeups of the pageout daemon. 1544 */ 1545 1546 static struct buf * 1547 getnewbuf(int slpflag, int slptimeo, int size, int maxsize) 1548 { 1549 struct buf *bp; 1550 struct buf *nbp; 1551 int defrag = 0; 1552 int nqindex; 1553 static int flushingbufs; 1554 1555 /* 1556 * We can't afford to block since we might be holding a vnode lock, 1557 * which may prevent system daemons from running. We deal with 1558 * low-memory situations by proactively returning memory and running 1559 * async I/O rather then sync I/O. 1560 */ 1561 1562 ++getnewbufcalls; 1563 --getnewbufrestarts; 1564 restart: 1565 ++getnewbufrestarts; 1566 1567 /* 1568 * Setup for scan. If we do not have enough free buffers, 1569 * we setup a degenerate case that immediately fails. Note 1570 * that if we are specially marked process, we are allowed to 1571 * dip into our reserves. 1572 * 1573 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 1574 * 1575 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 1576 * However, there are a number of cases (defragging, reusing, ...) 1577 * where we cannot backup. 1578 */ 1579 nqindex = BQUEUE_EMPTYKVA; 1580 nbp = TAILQ_FIRST(&bufqueues[BQUEUE_EMPTYKVA]); 1581 1582 if (nbp == NULL) { 1583 /* 1584 * If no EMPTYKVA buffers and we are either 1585 * defragging or reusing, locate a CLEAN buffer 1586 * to free or reuse. If bufspace useage is low 1587 * skip this step so we can allocate a new buffer. 1588 */ 1589 if (defrag || bufspace >= lobufspace) { 1590 nqindex = BQUEUE_CLEAN; 1591 nbp = TAILQ_FIRST(&bufqueues[BQUEUE_CLEAN]); 1592 } 1593 1594 /* 1595 * If we could not find or were not allowed to reuse a 1596 * CLEAN buffer, check to see if it is ok to use an EMPTY 1597 * buffer. We can only use an EMPTY buffer if allocating 1598 * its KVA would not otherwise run us out of buffer space. 1599 */ 1600 if (nbp == NULL && defrag == 0 && 1601 bufspace + maxsize < hibufspace) { 1602 nqindex = BQUEUE_EMPTY; 1603 nbp = TAILQ_FIRST(&bufqueues[BQUEUE_EMPTY]); 1604 } 1605 } 1606 1607 /* 1608 * Run scan, possibly freeing data and/or kva mappings on the fly 1609 * depending. 1610 */ 1611 1612 while ((bp = nbp) != NULL) { 1613 int qindex = nqindex; 1614 1615 /* 1616 * Calculate next bp ( we can only use it if we do not block 1617 * or do other fancy things ). 1618 */ 1619 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 1620 switch(qindex) { 1621 case BQUEUE_EMPTY: 1622 nqindex = BQUEUE_EMPTYKVA; 1623 if ((nbp = TAILQ_FIRST(&bufqueues[BQUEUE_EMPTYKVA]))) 1624 break; 1625 /* fall through */ 1626 case BQUEUE_EMPTYKVA: 1627 nqindex = BQUEUE_CLEAN; 1628 if ((nbp = TAILQ_FIRST(&bufqueues[BQUEUE_CLEAN]))) 1629 break; 1630 /* fall through */ 1631 case BQUEUE_CLEAN: 1632 /* 1633 * nbp is NULL. 1634 */ 1635 break; 1636 } 1637 } 1638 1639 /* 1640 * Sanity Checks 1641 */ 1642 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp)); 1643 1644 /* 1645 * Note: we no longer distinguish between VMIO and non-VMIO 1646 * buffers. 1647 */ 1648 1649 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); 1650 1651 /* 1652 * If we are defragging then we need a buffer with 1653 * b_kvasize != 0. XXX this situation should no longer 1654 * occur, if defrag is non-zero the buffer's b_kvasize 1655 * should also be non-zero at this point. XXX 1656 */ 1657 if (defrag && bp->b_kvasize == 0) { 1658 kprintf("Warning: defrag empty buffer %p\n", bp); 1659 continue; 1660 } 1661 1662 /* 1663 * Start freeing the bp. This is somewhat involved. nbp 1664 * remains valid only for BQUEUE_EMPTY[KVA] bp's. Buffers 1665 * on the clean list must be disassociated from their 1666 * current vnode. Buffers on the empty[kva] lists have 1667 * already been disassociated. 1668 */ 1669 1670 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) { 1671 kprintf("getnewbuf: warning, locked buf %p, race corrected\n", bp); 1672 tsleep(&bd_request, 0, "gnbxxx", hz / 100); 1673 goto restart; 1674 } 1675 if (bp->b_qindex != qindex) { 1676 kprintf("getnewbuf: warning, BUF_LOCK blocked unexpectedly on buf %p index %d->%d, race corrected\n", bp, qindex, bp->b_qindex); 1677 BUF_UNLOCK(bp); 1678 goto restart; 1679 } 1680 bremfree(bp); 1681 1682 if (qindex == BQUEUE_CLEAN) { 1683 if (bp->b_flags & B_VMIO) { 1684 bp->b_flags &= ~B_ASYNC; 1685 vfs_vmio_release(bp); 1686 } 1687 if (bp->b_vp) 1688 brelvp(bp); 1689 } 1690 1691 /* 1692 * NOTE: nbp is now entirely invalid. We can only restart 1693 * the scan from this point on. 1694 * 1695 * Get the rest of the buffer freed up. b_kva* is still 1696 * valid after this operation. 1697 */ 1698 1699 KASSERT(bp->b_vp == NULL, ("bp3 %p flags %08x vnode %p qindex %d unexpectededly still associated!", bp, bp->b_flags, bp->b_vp, qindex)); 1700 KKASSERT((bp->b_flags & B_HASHED) == 0); 1701 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_deallocate) 1702 (*bioops.io_deallocate)(bp); 1703 1704 /* 1705 * critical section protection is not required when 1706 * scrapping a buffer's contents because it is already 1707 * wired. 1708 */ 1709 if (bp->b_bufsize) 1710 allocbuf(bp, 0); 1711 1712 bp->b_flags = B_BNOCLIP; 1713 bp->b_cmd = BUF_CMD_DONE; 1714 bp->b_vp = NULL; 1715 bp->b_error = 0; 1716 bp->b_resid = 0; 1717 bp->b_bcount = 0; 1718 bp->b_xio.xio_npages = 0; 1719 bp->b_dirtyoff = bp->b_dirtyend = 0; 1720 reinitbufbio(bp); 1721 1722 LIST_INIT(&bp->b_dep); 1723 1724 /* 1725 * If we are defragging then free the buffer. 1726 */ 1727 if (defrag) { 1728 bp->b_flags |= B_INVAL; 1729 bfreekva(bp); 1730 brelse(bp); 1731 defrag = 0; 1732 goto restart; 1733 } 1734 1735 /* 1736 * If we are overcomitted then recover the buffer and its 1737 * KVM space. This occurs in rare situations when multiple 1738 * processes are blocked in getnewbuf() or allocbuf(). 1739 */ 1740 if (bufspace >= hibufspace) 1741 flushingbufs = 1; 1742 if (flushingbufs && bp->b_kvasize != 0) { 1743 bp->b_flags |= B_INVAL; 1744 bfreekva(bp); 1745 brelse(bp); 1746 goto restart; 1747 } 1748 if (bufspace < lobufspace) 1749 flushingbufs = 0; 1750 break; 1751 } 1752 1753 /* 1754 * If we exhausted our list, sleep as appropriate. We may have to 1755 * wakeup various daemons and write out some dirty buffers. 1756 * 1757 * Generally we are sleeping due to insufficient buffer space. 1758 */ 1759 1760 if (bp == NULL) { 1761 int flags; 1762 char *waitmsg; 1763 1764 if (defrag) { 1765 flags = VFS_BIO_NEED_BUFSPACE; 1766 waitmsg = "nbufkv"; 1767 } else if (bufspace >= hibufspace) { 1768 waitmsg = "nbufbs"; 1769 flags = VFS_BIO_NEED_BUFSPACE; 1770 } else { 1771 waitmsg = "newbuf"; 1772 flags = VFS_BIO_NEED_ANY; 1773 } 1774 1775 bd_speedup(); /* heeeelp */ 1776 1777 needsbuffer |= flags; 1778 while (needsbuffer & flags) { 1779 if (tsleep(&needsbuffer, slpflag, waitmsg, slptimeo)) 1780 return (NULL); 1781 } 1782 } else { 1783 /* 1784 * We finally have a valid bp. We aren't quite out of the 1785 * woods, we still have to reserve kva space. In order 1786 * to keep fragmentation sane we only allocate kva in 1787 * BKVASIZE chunks. 1788 */ 1789 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 1790 1791 if (maxsize != bp->b_kvasize) { 1792 vm_offset_t addr = 0; 1793 int count; 1794 1795 bfreekva(bp); 1796 1797 count = vm_map_entry_reserve(MAP_RESERVE_COUNT); 1798 vm_map_lock(&buffer_map); 1799 1800 if (vm_map_findspace(&buffer_map, 1801 vm_map_min(&buffer_map), maxsize, 1802 maxsize, &addr)) { 1803 /* 1804 * Uh oh. Buffer map is too fragmented. We 1805 * must defragment the map. 1806 */ 1807 vm_map_unlock(&buffer_map); 1808 vm_map_entry_release(count); 1809 ++bufdefragcnt; 1810 defrag = 1; 1811 bp->b_flags |= B_INVAL; 1812 brelse(bp); 1813 goto restart; 1814 } 1815 if (addr) { 1816 vm_map_insert(&buffer_map, &count, 1817 NULL, 0, 1818 addr, addr + maxsize, 1819 VM_MAPTYPE_NORMAL, 1820 VM_PROT_ALL, VM_PROT_ALL, 1821 MAP_NOFAULT); 1822 1823 bp->b_kvabase = (caddr_t) addr; 1824 bp->b_kvasize = maxsize; 1825 bufspace += bp->b_kvasize; 1826 ++bufreusecnt; 1827 } 1828 vm_map_unlock(&buffer_map); 1829 vm_map_entry_release(count); 1830 } 1831 bp->b_data = bp->b_kvabase; 1832 } 1833 return(bp); 1834 } 1835 1836 /* 1837 * buf_daemon: 1838 * 1839 * Buffer flushing daemon. Buffers are normally flushed by the 1840 * update daemon but if it cannot keep up this process starts to 1841 * take the load in an attempt to prevent getnewbuf() from blocking. 1842 */ 1843 1844 static struct thread *bufdaemonthread; 1845 1846 static struct kproc_desc buf_kp = { 1847 "bufdaemon", 1848 buf_daemon, 1849 &bufdaemonthread 1850 }; 1851 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp) 1852 1853 static void 1854 buf_daemon(void) 1855 { 1856 /* 1857 * This process needs to be suspended prior to shutdown sync. 1858 */ 1859 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc, 1860 bufdaemonthread, SHUTDOWN_PRI_LAST); 1861 1862 /* 1863 * This process is allowed to take the buffer cache to the limit 1864 */ 1865 crit_enter(); 1866 1867 for (;;) { 1868 kproc_suspend_loop(); 1869 1870 /* 1871 * Do the flush. Limit the amount of in-transit I/O we 1872 * allow to build up, otherwise we would completely saturate 1873 * the I/O system. Wakeup any waiting processes before we 1874 * normally would so they can run in parallel with our drain. 1875 */ 1876 while (numdirtybuffers > lodirtybuffers) { 1877 if (flushbufqueues() == 0) 1878 break; 1879 waitrunningbufspace(); 1880 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 1881 } 1882 1883 /* 1884 * Only clear bd_request if we have reached our low water 1885 * mark. The buf_daemon normally waits 5 seconds and 1886 * then incrementally flushes any dirty buffers that have 1887 * built up, within reason. 1888 * 1889 * If we were unable to hit our low water mark and couldn't 1890 * find any flushable buffers, we sleep half a second. 1891 * Otherwise we loop immediately. 1892 */ 1893 if (numdirtybuffers <= lodirtybuffers) { 1894 /* 1895 * We reached our low water mark, reset the 1896 * request and sleep until we are needed again. 1897 * The sleep is just so the suspend code works. 1898 */ 1899 spin_lock_wr(&needsbuffer_spin); 1900 bd_request = 0; 1901 msleep(&bd_request, &needsbuffer_spin, 0, "psleep", hz); 1902 spin_unlock_wr(&needsbuffer_spin); 1903 } else { 1904 /* 1905 * We couldn't find any flushable dirty buffers but 1906 * still have too many dirty buffers, we 1907 * have to sleep and try again. (rare) 1908 */ 1909 tsleep(&bd_request, 0, "qsleep", hz / 2); 1910 } 1911 } 1912 } 1913 1914 /* 1915 * flushbufqueues: 1916 * 1917 * Try to flush a buffer in the dirty queue. We must be careful to 1918 * free up B_INVAL buffers instead of write them, which NFS is 1919 * particularly sensitive to. 1920 */ 1921 1922 static int 1923 flushbufqueues(void) 1924 { 1925 struct buf *bp; 1926 int r = 0; 1927 1928 bp = TAILQ_FIRST(&bufqueues[BQUEUE_DIRTY]); 1929 1930 while (bp) { 1931 KASSERT((bp->b_flags & B_DELWRI), ("unexpected clean buffer %p", bp)); 1932 if (bp->b_flags & B_DELWRI) { 1933 if (bp->b_flags & B_INVAL) { 1934 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) 1935 panic("flushbufqueues: locked buf"); 1936 bremfree(bp); 1937 brelse(bp); 1938 ++r; 1939 break; 1940 } 1941 if (LIST_FIRST(&bp->b_dep) != NULL && 1942 bioops.io_countdeps && 1943 (bp->b_flags & B_DEFERRED) == 0 && 1944 (*bioops.io_countdeps)(bp, 0)) { 1945 TAILQ_REMOVE(&bufqueues[BQUEUE_DIRTY], 1946 bp, b_freelist); 1947 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_DIRTY], 1948 bp, b_freelist); 1949 bp->b_flags |= B_DEFERRED; 1950 bp = TAILQ_FIRST(&bufqueues[BQUEUE_DIRTY]); 1951 continue; 1952 } 1953 1954 /* 1955 * Only write it out if we can successfully lock 1956 * it. 1957 */ 1958 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) == 0) { 1959 vfs_bio_awrite(bp); 1960 ++r; 1961 break; 1962 } 1963 } 1964 bp = TAILQ_NEXT(bp, b_freelist); 1965 } 1966 return (r); 1967 } 1968 1969 /* 1970 * inmem: 1971 * 1972 * Returns true if no I/O is needed to access the associated VM object. 1973 * This is like findblk except it also hunts around in the VM system for 1974 * the data. 1975 * 1976 * Note that we ignore vm_page_free() races from interrupts against our 1977 * lookup, since if the caller is not protected our return value will not 1978 * be any more valid then otherwise once we exit the critical section. 1979 */ 1980 int 1981 inmem(struct vnode *vp, off_t loffset) 1982 { 1983 vm_object_t obj; 1984 vm_offset_t toff, tinc, size; 1985 vm_page_t m; 1986 1987 if (findblk(vp, loffset)) 1988 return 1; 1989 if (vp->v_mount == NULL) 1990 return 0; 1991 if ((obj = vp->v_object) == NULL) 1992 return 0; 1993 1994 size = PAGE_SIZE; 1995 if (size > vp->v_mount->mnt_stat.f_iosize) 1996 size = vp->v_mount->mnt_stat.f_iosize; 1997 1998 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 1999 m = vm_page_lookup(obj, OFF_TO_IDX(loffset + toff)); 2000 if (m == NULL) 2001 return 0; 2002 tinc = size; 2003 if (tinc > PAGE_SIZE - ((toff + loffset) & PAGE_MASK)) 2004 tinc = PAGE_SIZE - ((toff + loffset) & PAGE_MASK); 2005 if (vm_page_is_valid(m, 2006 (vm_offset_t) ((toff + loffset) & PAGE_MASK), tinc) == 0) 2007 return 0; 2008 } 2009 return 1; 2010 } 2011 2012 /* 2013 * vfs_setdirty: 2014 * 2015 * Sets the dirty range for a buffer based on the status of the dirty 2016 * bits in the pages comprising the buffer. 2017 * 2018 * The range is limited to the size of the buffer. 2019 * 2020 * This routine is primarily used by NFS, but is generalized for the 2021 * B_VMIO case. 2022 */ 2023 static void 2024 vfs_setdirty(struct buf *bp) 2025 { 2026 int i; 2027 vm_object_t object; 2028 2029 /* 2030 * Degenerate case - empty buffer 2031 */ 2032 2033 if (bp->b_bufsize == 0) 2034 return; 2035 2036 /* 2037 * We qualify the scan for modified pages on whether the 2038 * object has been flushed yet. The OBJ_WRITEABLE flag 2039 * is not cleared simply by protecting pages off. 2040 */ 2041 2042 if ((bp->b_flags & B_VMIO) == 0) 2043 return; 2044 2045 object = bp->b_xio.xio_pages[0]->object; 2046 2047 if ((object->flags & OBJ_WRITEABLE) && !(object->flags & OBJ_MIGHTBEDIRTY)) 2048 kprintf("Warning: object %p writeable but not mightbedirty\n", object); 2049 if (!(object->flags & OBJ_WRITEABLE) && (object->flags & OBJ_MIGHTBEDIRTY)) 2050 kprintf("Warning: object %p mightbedirty but not writeable\n", object); 2051 2052 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) { 2053 vm_offset_t boffset; 2054 vm_offset_t eoffset; 2055 2056 /* 2057 * test the pages to see if they have been modified directly 2058 * by users through the VM system. 2059 */ 2060 for (i = 0; i < bp->b_xio.xio_npages; i++) { 2061 vm_page_flag_clear(bp->b_xio.xio_pages[i], PG_ZERO); 2062 vm_page_test_dirty(bp->b_xio.xio_pages[i]); 2063 } 2064 2065 /* 2066 * Calculate the encompassing dirty range, boffset and eoffset, 2067 * (eoffset - boffset) bytes. 2068 */ 2069 2070 for (i = 0; i < bp->b_xio.xio_npages; i++) { 2071 if (bp->b_xio.xio_pages[i]->dirty) 2072 break; 2073 } 2074 boffset = (i << PAGE_SHIFT) - (bp->b_loffset & PAGE_MASK); 2075 2076 for (i = bp->b_xio.xio_npages - 1; i >= 0; --i) { 2077 if (bp->b_xio.xio_pages[i]->dirty) { 2078 break; 2079 } 2080 } 2081 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_loffset & PAGE_MASK); 2082 2083 /* 2084 * Fit it to the buffer. 2085 */ 2086 2087 if (eoffset > bp->b_bcount) 2088 eoffset = bp->b_bcount; 2089 2090 /* 2091 * If we have a good dirty range, merge with the existing 2092 * dirty range. 2093 */ 2094 2095 if (boffset < eoffset) { 2096 if (bp->b_dirtyoff > boffset) 2097 bp->b_dirtyoff = boffset; 2098 if (bp->b_dirtyend < eoffset) 2099 bp->b_dirtyend = eoffset; 2100 } 2101 } 2102 } 2103 2104 /* 2105 * findblk: 2106 * 2107 * Locate and return the specified buffer, or NULL if the buffer does 2108 * not exist. Do not attempt to lock the buffer or manipulate it in 2109 * any way. The caller must validate that the correct buffer has been 2110 * obtain after locking it. 2111 */ 2112 struct buf * 2113 findblk(struct vnode *vp, off_t loffset) 2114 { 2115 struct buf *bp; 2116 2117 crit_enter(); 2118 bp = buf_rb_hash_RB_LOOKUP(&vp->v_rbhash_tree, loffset); 2119 crit_exit(); 2120 return(bp); 2121 } 2122 2123 /* 2124 * getblk: 2125 * 2126 * Get a block given a specified block and offset into a file/device. 2127 * B_INVAL may or may not be set on return. The caller should clear 2128 * B_INVAL prior to initiating a READ. 2129 * 2130 * IT IS IMPORTANT TO UNDERSTAND THAT IF YOU CALL GETBLK() AND B_CACHE 2131 * IS NOT SET, YOU MUST INITIALIZE THE RETURNED BUFFER, ISSUE A READ, 2132 * OR SET B_INVAL BEFORE RETIRING IT. If you retire a getblk'd buffer 2133 * without doing any of those things the system will likely believe 2134 * the buffer to be valid (especially if it is not B_VMIO), and the 2135 * next getblk() will return the buffer with B_CACHE set. 2136 * 2137 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2138 * an existing buffer. 2139 * 2140 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2141 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2142 * and then cleared based on the backing VM. If the previous buffer is 2143 * non-0-sized but invalid, B_CACHE will be cleared. 2144 * 2145 * If getblk() must create a new buffer, the new buffer is returned with 2146 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2147 * case it is returned with B_INVAL clear and B_CACHE set based on the 2148 * backing VM. 2149 * 2150 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 2151 * B_CACHE bit is clear. 2152 * 2153 * What this means, basically, is that the caller should use B_CACHE to 2154 * determine whether the buffer is fully valid or not and should clear 2155 * B_INVAL prior to issuing a read. If the caller intends to validate 2156 * the buffer by loading its data area with something, the caller needs 2157 * to clear B_INVAL. If the caller does this without issuing an I/O, 2158 * the caller should set B_CACHE ( as an optimization ), else the caller 2159 * should issue the I/O and biodone() will set B_CACHE if the I/O was 2160 * a write attempt or if it was a successfull read. If the caller 2161 * intends to issue a READ, the caller must clear B_INVAL and B_ERROR 2162 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 2163 */ 2164 struct buf * 2165 getblk(struct vnode *vp, off_t loffset, int size, int slpflag, int slptimeo) 2166 { 2167 struct buf *bp; 2168 2169 if (size > MAXBSIZE) 2170 panic("getblk: size(%d) > MAXBSIZE(%d)", size, MAXBSIZE); 2171 if (vp->v_object == NULL) 2172 panic("getblk: vnode %p has no object!", vp); 2173 2174 crit_enter(); 2175 loop: 2176 /* 2177 * Block if we are low on buffers. Certain processes are allowed 2178 * to completely exhaust the buffer cache. 2179 * 2180 * If this check ever becomes a bottleneck it may be better to 2181 * move it into the else, when findblk() fails. At the moment 2182 * it isn't a problem. 2183 * 2184 * XXX remove, we cannot afford to block anywhere if holding a vnode 2185 * lock in low-memory situation, so take it to the max. 2186 */ 2187 if (numfreebuffers == 0) { 2188 if (!curproc) 2189 return NULL; 2190 needsbuffer |= VFS_BIO_NEED_ANY; 2191 tsleep(&needsbuffer, slpflag, "newbuf", slptimeo); 2192 } 2193 2194 if ((bp = findblk(vp, loffset))) { 2195 /* 2196 * The buffer was found in the cache, but we need to lock it. 2197 * Even with LK_NOWAIT the lockmgr may break our critical 2198 * section, so double-check the validity of the buffer 2199 * once the lock has been obtained. 2200 */ 2201 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) { 2202 int lkflags = LK_EXCLUSIVE | LK_SLEEPFAIL; 2203 if (slpflag & PCATCH) 2204 lkflags |= LK_PCATCH; 2205 if (BUF_TIMELOCK(bp, lkflags, "getblk", slptimeo) == 2206 ENOLCK) { 2207 goto loop; 2208 } 2209 crit_exit(); 2210 return (NULL); 2211 } 2212 2213 /* 2214 * Once the buffer has been locked, make sure we didn't race 2215 * a buffer recyclement. Buffers that are no longer hashed 2216 * will have b_vp == NULL, so this takes care of that check 2217 * as well. 2218 */ 2219 if (bp->b_vp != vp || bp->b_loffset != loffset) { 2220 kprintf("Warning buffer %p (vp %p loffset %lld) was recycled\n", bp, vp, loffset); 2221 BUF_UNLOCK(bp); 2222 goto loop; 2223 } 2224 2225 /* 2226 * All vnode-based buffers must be backed by a VM object. 2227 */ 2228 KKASSERT(bp->b_flags & B_VMIO); 2229 KKASSERT(bp->b_cmd == BUF_CMD_DONE); 2230 2231 /* 2232 * Make sure that B_INVAL buffers do not have a cached 2233 * block number translation. 2234 */ 2235 if ((bp->b_flags & B_INVAL) && (bp->b_bio2.bio_offset != NOOFFSET)) { 2236 kprintf("Warning invalid buffer %p (vp %p loffset %lld) did not have cleared bio_offset cache\n", bp, vp, loffset); 2237 clearbiocache(&bp->b_bio2); 2238 } 2239 2240 /* 2241 * The buffer is locked. B_CACHE is cleared if the buffer is 2242 * invalid. 2243 */ 2244 if (bp->b_flags & B_INVAL) 2245 bp->b_flags &= ~B_CACHE; 2246 bremfree(bp); 2247 2248 /* 2249 * Any size inconsistancy with a dirty buffer or a buffer 2250 * with a softupdates dependancy must be resolved. Resizing 2251 * the buffer in such circumstances can lead to problems. 2252 */ 2253 if (size != bp->b_bcount) { 2254 if (bp->b_flags & B_DELWRI) { 2255 bp->b_flags |= B_NOCACHE; 2256 bwrite(bp); 2257 } else if (LIST_FIRST(&bp->b_dep)) { 2258 bp->b_flags |= B_NOCACHE; 2259 bwrite(bp); 2260 } else { 2261 bp->b_flags |= B_RELBUF; 2262 brelse(bp); 2263 } 2264 goto loop; 2265 } 2266 KKASSERT(size <= bp->b_kvasize); 2267 KASSERT(bp->b_loffset != NOOFFSET, 2268 ("getblk: no buffer offset")); 2269 2270 /* 2271 * A buffer with B_DELWRI set and B_CACHE clear must 2272 * be committed before we can return the buffer in 2273 * order to prevent the caller from issuing a read 2274 * ( due to B_CACHE not being set ) and overwriting 2275 * it. 2276 * 2277 * Most callers, including NFS and FFS, need this to 2278 * operate properly either because they assume they 2279 * can issue a read if B_CACHE is not set, or because 2280 * ( for example ) an uncached B_DELWRI might loop due 2281 * to softupdates re-dirtying the buffer. In the latter 2282 * case, B_CACHE is set after the first write completes, 2283 * preventing further loops. 2284 * 2285 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 2286 * above while extending the buffer, we cannot allow the 2287 * buffer to remain with B_CACHE set after the write 2288 * completes or it will represent a corrupt state. To 2289 * deal with this we set B_NOCACHE to scrap the buffer 2290 * after the write. 2291 * 2292 * We might be able to do something fancy, like setting 2293 * B_CACHE in bwrite() except if B_DELWRI is already set, 2294 * so the below call doesn't set B_CACHE, but that gets real 2295 * confusing. This is much easier. 2296 */ 2297 2298 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 2299 bp->b_flags |= B_NOCACHE; 2300 bwrite(bp); 2301 goto loop; 2302 } 2303 crit_exit(); 2304 } else { 2305 /* 2306 * Buffer is not in-core, create new buffer. The buffer 2307 * returned by getnewbuf() is locked. Note that the returned 2308 * buffer is also considered valid (not marked B_INVAL). 2309 * 2310 * Calculating the offset for the I/O requires figuring out 2311 * the block size. We use DEV_BSIZE for VBLK or VCHR and 2312 * the mount's f_iosize otherwise. If the vnode does not 2313 * have an associated mount we assume that the passed size is 2314 * the block size. 2315 * 2316 * Note that vn_isdisk() cannot be used here since it may 2317 * return a failure for numerous reasons. Note that the 2318 * buffer size may be larger then the block size (the caller 2319 * will use block numbers with the proper multiple). Beware 2320 * of using any v_* fields which are part of unions. In 2321 * particular, in DragonFly the mount point overloading 2322 * mechanism uses the namecache only and the underlying 2323 * directory vnode is not a special case. 2324 */ 2325 int bsize, maxsize; 2326 2327 if (vp->v_type == VBLK || vp->v_type == VCHR) 2328 bsize = DEV_BSIZE; 2329 else if (vp->v_mount) 2330 bsize = vp->v_mount->mnt_stat.f_iosize; 2331 else 2332 bsize = size; 2333 2334 maxsize = size + (loffset & PAGE_MASK); 2335 maxsize = imax(maxsize, bsize); 2336 2337 if ((bp = getnewbuf(slpflag, slptimeo, size, maxsize)) == NULL) { 2338 if (slpflag || slptimeo) { 2339 crit_exit(); 2340 return NULL; 2341 } 2342 goto loop; 2343 } 2344 2345 /* 2346 * This code is used to make sure that a buffer is not 2347 * created while the getnewbuf routine is blocked. 2348 * This can be a problem whether the vnode is locked or not. 2349 * If the buffer is created out from under us, we have to 2350 * throw away the one we just created. There is no window 2351 * race because we are safely running in a critical section 2352 * from the point of the duplicate buffer creation through 2353 * to here, and we've locked the buffer. 2354 */ 2355 if (findblk(vp, loffset)) { 2356 bp->b_flags |= B_INVAL; 2357 brelse(bp); 2358 goto loop; 2359 } 2360 2361 /* 2362 * Insert the buffer into the hash, so that it can 2363 * be found by findblk(). 2364 * 2365 * Make sure the translation layer has been cleared. 2366 */ 2367 bp->b_loffset = loffset; 2368 bp->b_bio2.bio_offset = NOOFFSET; 2369 /* bp->b_bio2.bio_next = NULL; */ 2370 2371 bgetvp(vp, bp); 2372 2373 /* 2374 * All vnode-based buffers must be backed by a VM object. 2375 */ 2376 KKASSERT(vp->v_object != NULL); 2377 bp->b_flags |= B_VMIO; 2378 KKASSERT(bp->b_cmd == BUF_CMD_DONE); 2379 2380 allocbuf(bp, size); 2381 2382 crit_exit(); 2383 } 2384 return (bp); 2385 } 2386 2387 /* 2388 * geteblk: 2389 * 2390 * Get an empty, disassociated buffer of given size. The buffer is 2391 * initially set to B_INVAL. 2392 * 2393 * critical section protection is not required for the allocbuf() 2394 * call because races are impossible here. 2395 */ 2396 struct buf * 2397 geteblk(int size) 2398 { 2399 struct buf *bp; 2400 int maxsize; 2401 2402 maxsize = (size + BKVAMASK) & ~BKVAMASK; 2403 2404 crit_enter(); 2405 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0) 2406 ; 2407 crit_exit(); 2408 allocbuf(bp, size); 2409 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 2410 return (bp); 2411 } 2412 2413 2414 /* 2415 * allocbuf: 2416 * 2417 * This code constitutes the buffer memory from either anonymous system 2418 * memory (in the case of non-VMIO operations) or from an associated 2419 * VM object (in the case of VMIO operations). This code is able to 2420 * resize a buffer up or down. 2421 * 2422 * Note that this code is tricky, and has many complications to resolve 2423 * deadlock or inconsistant data situations. Tread lightly!!! 2424 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 2425 * the caller. Calling this code willy nilly can result in the loss of data. 2426 * 2427 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 2428 * B_CACHE for the non-VMIO case. 2429 * 2430 * This routine does not need to be called from a critical section but you 2431 * must own the buffer. 2432 */ 2433 int 2434 allocbuf(struct buf *bp, int size) 2435 { 2436 int newbsize, mbsize; 2437 int i; 2438 2439 if (BUF_REFCNT(bp) == 0) 2440 panic("allocbuf: buffer not busy"); 2441 2442 if (bp->b_kvasize < size) 2443 panic("allocbuf: buffer too small"); 2444 2445 if ((bp->b_flags & B_VMIO) == 0) { 2446 caddr_t origbuf; 2447 int origbufsize; 2448 /* 2449 * Just get anonymous memory from the kernel. Don't 2450 * mess with B_CACHE. 2451 */ 2452 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2453 if (bp->b_flags & B_MALLOC) 2454 newbsize = mbsize; 2455 else 2456 newbsize = round_page(size); 2457 2458 if (newbsize < bp->b_bufsize) { 2459 /* 2460 * Malloced buffers are not shrunk 2461 */ 2462 if (bp->b_flags & B_MALLOC) { 2463 if (newbsize) { 2464 bp->b_bcount = size; 2465 } else { 2466 kfree(bp->b_data, M_BIOBUF); 2467 if (bp->b_bufsize) { 2468 bufmallocspace -= bp->b_bufsize; 2469 bufspacewakeup(); 2470 bp->b_bufsize = 0; 2471 } 2472 bp->b_data = bp->b_kvabase; 2473 bp->b_bcount = 0; 2474 bp->b_flags &= ~B_MALLOC; 2475 } 2476 return 1; 2477 } 2478 vm_hold_free_pages( 2479 bp, 2480 (vm_offset_t) bp->b_data + newbsize, 2481 (vm_offset_t) bp->b_data + bp->b_bufsize); 2482 } else if (newbsize > bp->b_bufsize) { 2483 /* 2484 * We only use malloced memory on the first allocation. 2485 * and revert to page-allocated memory when the buffer 2486 * grows. 2487 */ 2488 if ((bufmallocspace < maxbufmallocspace) && 2489 (bp->b_bufsize == 0) && 2490 (mbsize <= PAGE_SIZE/2)) { 2491 2492 bp->b_data = kmalloc(mbsize, M_BIOBUF, M_WAITOK); 2493 bp->b_bufsize = mbsize; 2494 bp->b_bcount = size; 2495 bp->b_flags |= B_MALLOC; 2496 bufmallocspace += mbsize; 2497 return 1; 2498 } 2499 origbuf = NULL; 2500 origbufsize = 0; 2501 /* 2502 * If the buffer is growing on its other-than-first 2503 * allocation, then we revert to the page-allocation 2504 * scheme. 2505 */ 2506 if (bp->b_flags & B_MALLOC) { 2507 origbuf = bp->b_data; 2508 origbufsize = bp->b_bufsize; 2509 bp->b_data = bp->b_kvabase; 2510 if (bp->b_bufsize) { 2511 bufmallocspace -= bp->b_bufsize; 2512 bufspacewakeup(); 2513 bp->b_bufsize = 0; 2514 } 2515 bp->b_flags &= ~B_MALLOC; 2516 newbsize = round_page(newbsize); 2517 } 2518 vm_hold_load_pages( 2519 bp, 2520 (vm_offset_t) bp->b_data + bp->b_bufsize, 2521 (vm_offset_t) bp->b_data + newbsize); 2522 if (origbuf) { 2523 bcopy(origbuf, bp->b_data, origbufsize); 2524 kfree(origbuf, M_BIOBUF); 2525 } 2526 } 2527 } else { 2528 vm_page_t m; 2529 int desiredpages; 2530 2531 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2532 desiredpages = ((int)(bp->b_loffset & PAGE_MASK) + 2533 newbsize + PAGE_MASK) >> PAGE_SHIFT; 2534 KKASSERT(desiredpages <= XIO_INTERNAL_PAGES); 2535 2536 if (bp->b_flags & B_MALLOC) 2537 panic("allocbuf: VMIO buffer can't be malloced"); 2538 /* 2539 * Set B_CACHE initially if buffer is 0 length or will become 2540 * 0-length. 2541 */ 2542 if (size == 0 || bp->b_bufsize == 0) 2543 bp->b_flags |= B_CACHE; 2544 2545 if (newbsize < bp->b_bufsize) { 2546 /* 2547 * DEV_BSIZE aligned new buffer size is less then the 2548 * DEV_BSIZE aligned existing buffer size. Figure out 2549 * if we have to remove any pages. 2550 */ 2551 if (desiredpages < bp->b_xio.xio_npages) { 2552 for (i = desiredpages; i < bp->b_xio.xio_npages; i++) { 2553 /* 2554 * the page is not freed here -- it 2555 * is the responsibility of 2556 * vnode_pager_setsize 2557 */ 2558 m = bp->b_xio.xio_pages[i]; 2559 KASSERT(m != bogus_page, 2560 ("allocbuf: bogus page found")); 2561 while (vm_page_sleep_busy(m, TRUE, "biodep")) 2562 ; 2563 2564 bp->b_xio.xio_pages[i] = NULL; 2565 vm_page_unwire(m, 0); 2566 } 2567 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) + 2568 (desiredpages << PAGE_SHIFT), (bp->b_xio.xio_npages - desiredpages)); 2569 bp->b_xio.xio_npages = desiredpages; 2570 } 2571 } else if (size > bp->b_bcount) { 2572 /* 2573 * We are growing the buffer, possibly in a 2574 * byte-granular fashion. 2575 */ 2576 struct vnode *vp; 2577 vm_object_t obj; 2578 vm_offset_t toff; 2579 vm_offset_t tinc; 2580 2581 /* 2582 * Step 1, bring in the VM pages from the object, 2583 * allocating them if necessary. We must clear 2584 * B_CACHE if these pages are not valid for the 2585 * range covered by the buffer. 2586 * 2587 * critical section protection is required to protect 2588 * against interrupts unbusying and freeing pages 2589 * between our vm_page_lookup() and our 2590 * busycheck/wiring call. 2591 */ 2592 vp = bp->b_vp; 2593 obj = vp->v_object; 2594 2595 crit_enter(); 2596 while (bp->b_xio.xio_npages < desiredpages) { 2597 vm_page_t m; 2598 vm_pindex_t pi; 2599 2600 pi = OFF_TO_IDX(bp->b_loffset) + bp->b_xio.xio_npages; 2601 if ((m = vm_page_lookup(obj, pi)) == NULL) { 2602 /* 2603 * note: must allocate system pages 2604 * since blocking here could intefere 2605 * with paging I/O, no matter which 2606 * process we are. 2607 */ 2608 m = vm_page_alloc(obj, pi, VM_ALLOC_NORMAL | VM_ALLOC_SYSTEM); 2609 if (m == NULL) { 2610 vm_wait(); 2611 vm_pageout_deficit += desiredpages - 2612 bp->b_xio.xio_npages; 2613 } else { 2614 vm_page_wire(m); 2615 vm_page_wakeup(m); 2616 bp->b_flags &= ~B_CACHE; 2617 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 2618 ++bp->b_xio.xio_npages; 2619 } 2620 continue; 2621 } 2622 2623 /* 2624 * We found a page. If we have to sleep on it, 2625 * retry because it might have gotten freed out 2626 * from under us. 2627 * 2628 * We can only test PG_BUSY here. Blocking on 2629 * m->busy might lead to a deadlock: 2630 * 2631 * vm_fault->getpages->cluster_read->allocbuf 2632 * 2633 */ 2634 2635 if (vm_page_sleep_busy(m, FALSE, "pgtblk")) 2636 continue; 2637 2638 /* 2639 * We have a good page. Should we wakeup the 2640 * page daemon? 2641 */ 2642 if ((curthread != pagethread) && 2643 ((m->queue - m->pc) == PQ_CACHE) && 2644 ((vmstats.v_free_count + vmstats.v_cache_count) < 2645 (vmstats.v_free_min + vmstats.v_cache_min))) { 2646 pagedaemon_wakeup(); 2647 } 2648 vm_page_flag_clear(m, PG_ZERO); 2649 vm_page_wire(m); 2650 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 2651 ++bp->b_xio.xio_npages; 2652 } 2653 crit_exit(); 2654 2655 /* 2656 * Step 2. We've loaded the pages into the buffer, 2657 * we have to figure out if we can still have B_CACHE 2658 * set. Note that B_CACHE is set according to the 2659 * byte-granular range ( bcount and size ), not the 2660 * aligned range ( newbsize ). 2661 * 2662 * The VM test is against m->valid, which is DEV_BSIZE 2663 * aligned. Needless to say, the validity of the data 2664 * needs to also be DEV_BSIZE aligned. Note that this 2665 * fails with NFS if the server or some other client 2666 * extends the file's EOF. If our buffer is resized, 2667 * B_CACHE may remain set! XXX 2668 */ 2669 2670 toff = bp->b_bcount; 2671 tinc = PAGE_SIZE - ((bp->b_loffset + toff) & PAGE_MASK); 2672 2673 while ((bp->b_flags & B_CACHE) && toff < size) { 2674 vm_pindex_t pi; 2675 2676 if (tinc > (size - toff)) 2677 tinc = size - toff; 2678 2679 pi = ((bp->b_loffset & PAGE_MASK) + toff) >> 2680 PAGE_SHIFT; 2681 2682 vfs_buf_test_cache( 2683 bp, 2684 bp->b_loffset, 2685 toff, 2686 tinc, 2687 bp->b_xio.xio_pages[pi] 2688 ); 2689 toff += tinc; 2690 tinc = PAGE_SIZE; 2691 } 2692 2693 /* 2694 * Step 3, fixup the KVM pmap. Remember that 2695 * bp->b_data is relative to bp->b_loffset, but 2696 * bp->b_loffset may be offset into the first page. 2697 */ 2698 2699 bp->b_data = (caddr_t) 2700 trunc_page((vm_offset_t)bp->b_data); 2701 pmap_qenter( 2702 (vm_offset_t)bp->b_data, 2703 bp->b_xio.xio_pages, 2704 bp->b_xio.xio_npages 2705 ); 2706 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 2707 (vm_offset_t)(bp->b_loffset & PAGE_MASK)); 2708 } 2709 } 2710 if (newbsize < bp->b_bufsize) 2711 bufspacewakeup(); 2712 bp->b_bufsize = newbsize; /* actual buffer allocation */ 2713 bp->b_bcount = size; /* requested buffer size */ 2714 return 1; 2715 } 2716 2717 /* 2718 * biowait: 2719 * 2720 * Wait for buffer I/O completion, returning error status. The buffer 2721 * is left locked on return. B_EINTR is converted into an EINTR error 2722 * and cleared. 2723 * 2724 * NOTE! The original b_cmd is lost on return, since b_cmd will be 2725 * set to BUF_CMD_DONE. 2726 */ 2727 int 2728 biowait(struct buf *bp) 2729 { 2730 crit_enter(); 2731 while (bp->b_cmd != BUF_CMD_DONE) { 2732 if (bp->b_cmd == BUF_CMD_READ) 2733 tsleep(bp, 0, "biord", 0); 2734 else 2735 tsleep(bp, 0, "biowr", 0); 2736 } 2737 crit_exit(); 2738 if (bp->b_flags & B_EINTR) { 2739 bp->b_flags &= ~B_EINTR; 2740 return (EINTR); 2741 } 2742 if (bp->b_flags & B_ERROR) { 2743 return (bp->b_error ? bp->b_error : EIO); 2744 } else { 2745 return (0); 2746 } 2747 } 2748 2749 /* 2750 * This associates a tracking count with an I/O. vn_strategy() and 2751 * dev_dstrategy() do this automatically but there are a few cases 2752 * where a vnode or device layer is bypassed when a block translation 2753 * is cached. In such cases bio_start_transaction() may be called on 2754 * the bypassed layers so the system gets an I/O in progress indication 2755 * for those higher layers. 2756 */ 2757 void 2758 bio_start_transaction(struct bio *bio, struct bio_track *track) 2759 { 2760 bio->bio_track = track; 2761 atomic_add_int(&track->bk_active, 1); 2762 } 2763 2764 /* 2765 * Initiate I/O on a vnode. 2766 */ 2767 void 2768 vn_strategy(struct vnode *vp, struct bio *bio) 2769 { 2770 struct bio_track *track; 2771 2772 KKASSERT(bio->bio_buf->b_cmd != BUF_CMD_DONE); 2773 if (bio->bio_buf->b_cmd == BUF_CMD_READ) 2774 track = &vp->v_track_read; 2775 else 2776 track = &vp->v_track_write; 2777 bio->bio_track = track; 2778 atomic_add_int(&track->bk_active, 1); 2779 vop_strategy(*vp->v_ops, vp, bio); 2780 } 2781 2782 2783 /* 2784 * biodone: 2785 * 2786 * Finish I/O on a buffer, optionally calling a completion function. 2787 * This is usually called from an interrupt so process blocking is 2788 * not allowed. 2789 * 2790 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 2791 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 2792 * assuming B_INVAL is clear. 2793 * 2794 * For the VMIO case, we set B_CACHE if the op was a read and no 2795 * read error occured, or if the op was a write. B_CACHE is never 2796 * set if the buffer is invalid or otherwise uncacheable. 2797 * 2798 * biodone does not mess with B_INVAL, allowing the I/O routine or the 2799 * initiator to leave B_INVAL set to brelse the buffer out of existance 2800 * in the biodone routine. 2801 */ 2802 void 2803 biodone(struct bio *bio) 2804 { 2805 struct buf *bp = bio->bio_buf; 2806 buf_cmd_t cmd; 2807 2808 crit_enter(); 2809 2810 KASSERT(BUF_REFCNTNB(bp) > 0, 2811 ("biodone: bp %p not busy %d", bp, BUF_REFCNTNB(bp))); 2812 KASSERT(bp->b_cmd != BUF_CMD_DONE, 2813 ("biodone: bp %p already done!", bp)); 2814 2815 runningbufwakeup(bp); 2816 2817 /* 2818 * Run up the chain of BIO's. Leave b_cmd intact for the duration. 2819 */ 2820 while (bio) { 2821 biodone_t *done_func; 2822 struct bio_track *track; 2823 2824 /* 2825 * BIO tracking. Most but not all BIOs are tracked. 2826 */ 2827 if ((track = bio->bio_track) != NULL) { 2828 atomic_subtract_int(&track->bk_active, 1); 2829 if (track->bk_active < 0) { 2830 panic("biodone: bad active count bio %p\n", 2831 bio); 2832 } 2833 if (track->bk_waitflag) { 2834 track->bk_waitflag = 0; 2835 wakeup(track); 2836 } 2837 bio->bio_track = NULL; 2838 } 2839 2840 /* 2841 * A bio_done function terminates the loop. The function 2842 * will be responsible for any further chaining and/or 2843 * buffer management. 2844 * 2845 * WARNING! The done function can deallocate the buffer! 2846 */ 2847 if ((done_func = bio->bio_done) != NULL) { 2848 bio->bio_done = NULL; 2849 done_func(bio); 2850 crit_exit(); 2851 return; 2852 } 2853 bio = bio->bio_prev; 2854 } 2855 2856 cmd = bp->b_cmd; 2857 bp->b_cmd = BUF_CMD_DONE; 2858 2859 /* 2860 * Only reads and writes are processed past this point. 2861 */ 2862 if (cmd != BUF_CMD_READ && cmd != BUF_CMD_WRITE) { 2863 brelse(bp); 2864 crit_exit(); 2865 return; 2866 } 2867 2868 /* 2869 * Warning: softupdates may re-dirty the buffer. 2870 */ 2871 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_complete) 2872 (*bioops.io_complete)(bp); 2873 2874 if (bp->b_flags & B_VMIO) { 2875 int i; 2876 vm_ooffset_t foff; 2877 vm_page_t m; 2878 vm_object_t obj; 2879 int iosize; 2880 struct vnode *vp = bp->b_vp; 2881 2882 obj = vp->v_object; 2883 2884 #if defined(VFS_BIO_DEBUG) 2885 if (vp->v_holdcnt == 0) 2886 panic("biodone: zero vnode hold count"); 2887 if ((vp->v_flag & VOBJBUF) == 0) 2888 panic("biodone: vnode is not setup for merged cache"); 2889 #endif 2890 2891 foff = bp->b_loffset; 2892 KASSERT(foff != NOOFFSET, ("biodone: no buffer offset")); 2893 KASSERT(obj != NULL, ("biodone: missing VM object")); 2894 2895 #if defined(VFS_BIO_DEBUG) 2896 if (obj->paging_in_progress < bp->b_xio.xio_npages) { 2897 kprintf("biodone: paging in progress(%d) < bp->b_xio.xio_npages(%d)\n", 2898 obj->paging_in_progress, bp->b_xio.xio_npages); 2899 } 2900 #endif 2901 2902 /* 2903 * Set B_CACHE if the op was a normal read and no error 2904 * occured. B_CACHE is set for writes in the b*write() 2905 * routines. 2906 */ 2907 iosize = bp->b_bcount - bp->b_resid; 2908 if (cmd == BUF_CMD_READ && (bp->b_flags & (B_INVAL|B_NOCACHE|B_ERROR)) == 0) { 2909 bp->b_flags |= B_CACHE; 2910 } 2911 2912 for (i = 0; i < bp->b_xio.xio_npages; i++) { 2913 int bogusflag = 0; 2914 int resid; 2915 2916 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 2917 if (resid > iosize) 2918 resid = iosize; 2919 2920 /* 2921 * cleanup bogus pages, restoring the originals. Since 2922 * the originals should still be wired, we don't have 2923 * to worry about interrupt/freeing races destroying 2924 * the VM object association. 2925 */ 2926 m = bp->b_xio.xio_pages[i]; 2927 if (m == bogus_page) { 2928 bogusflag = 1; 2929 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 2930 if (m == NULL) 2931 panic("biodone: page disappeared"); 2932 bp->b_xio.xio_pages[i] = m; 2933 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 2934 bp->b_xio.xio_pages, bp->b_xio.xio_npages); 2935 } 2936 #if defined(VFS_BIO_DEBUG) 2937 if (OFF_TO_IDX(foff) != m->pindex) { 2938 kprintf( 2939 "biodone: foff(%lu)/m->pindex(%d) mismatch\n", 2940 (unsigned long)foff, m->pindex); 2941 } 2942 #endif 2943 2944 /* 2945 * In the write case, the valid and clean bits are 2946 * already changed correctly ( see bdwrite() ), so we 2947 * only need to do this here in the read case. 2948 */ 2949 if (cmd == BUF_CMD_READ && !bogusflag && resid > 0) { 2950 vfs_page_set_valid(bp, foff, i, m); 2951 } 2952 vm_page_flag_clear(m, PG_ZERO); 2953 2954 /* 2955 * when debugging new filesystems or buffer I/O methods, this 2956 * is the most common error that pops up. if you see this, you 2957 * have not set the page busy flag correctly!!! 2958 */ 2959 if (m->busy == 0) { 2960 kprintf("biodone: page busy < 0, " 2961 "pindex: %d, foff: 0x(%x,%x), " 2962 "resid: %d, index: %d\n", 2963 (int) m->pindex, (int)(foff >> 32), 2964 (int) foff & 0xffffffff, resid, i); 2965 if (!vn_isdisk(vp, NULL)) 2966 kprintf(" iosize: %ld, loffset: %lld, flags: 0x%08x, npages: %d\n", 2967 bp->b_vp->v_mount->mnt_stat.f_iosize, 2968 bp->b_loffset, 2969 bp->b_flags, bp->b_xio.xio_npages); 2970 else 2971 kprintf(" VDEV, loffset: %lld, flags: 0x%08x, npages: %d\n", 2972 bp->b_loffset, 2973 bp->b_flags, bp->b_xio.xio_npages); 2974 kprintf(" valid: 0x%x, dirty: 0x%x, wired: %d\n", 2975 m->valid, m->dirty, m->wire_count); 2976 panic("biodone: page busy < 0"); 2977 } 2978 vm_page_io_finish(m); 2979 vm_object_pip_subtract(obj, 1); 2980 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2981 iosize -= resid; 2982 } 2983 if (obj) 2984 vm_object_pip_wakeupn(obj, 0); 2985 } 2986 2987 /* 2988 * For asynchronous completions, release the buffer now. The brelse 2989 * will do a wakeup there if necessary - so no need to do a wakeup 2990 * here in the async case. The sync case always needs to do a wakeup. 2991 */ 2992 2993 if (bp->b_flags & B_ASYNC) { 2994 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR | B_RELBUF)) != 0) 2995 brelse(bp); 2996 else 2997 bqrelse(bp); 2998 } else { 2999 wakeup(bp); 3000 } 3001 crit_exit(); 3002 } 3003 3004 /* 3005 * vfs_unbusy_pages: 3006 * 3007 * This routine is called in lieu of iodone in the case of 3008 * incomplete I/O. This keeps the busy status for pages 3009 * consistant. 3010 */ 3011 void 3012 vfs_unbusy_pages(struct buf *bp) 3013 { 3014 int i; 3015 3016 runningbufwakeup(bp); 3017 if (bp->b_flags & B_VMIO) { 3018 struct vnode *vp = bp->b_vp; 3019 vm_object_t obj; 3020 3021 obj = vp->v_object; 3022 3023 for (i = 0; i < bp->b_xio.xio_npages; i++) { 3024 vm_page_t m = bp->b_xio.xio_pages[i]; 3025 3026 /* 3027 * When restoring bogus changes the original pages 3028 * should still be wired, so we are in no danger of 3029 * losing the object association and do not need 3030 * critical section protection particularly. 3031 */ 3032 if (m == bogus_page) { 3033 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_loffset) + i); 3034 if (!m) { 3035 panic("vfs_unbusy_pages: page missing"); 3036 } 3037 bp->b_xio.xio_pages[i] = m; 3038 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3039 bp->b_xio.xio_pages, bp->b_xio.xio_npages); 3040 } 3041 vm_object_pip_subtract(obj, 1); 3042 vm_page_flag_clear(m, PG_ZERO); 3043 vm_page_io_finish(m); 3044 } 3045 vm_object_pip_wakeupn(obj, 0); 3046 } 3047 } 3048 3049 /* 3050 * vfs_page_set_valid: 3051 * 3052 * Set the valid bits in a page based on the supplied offset. The 3053 * range is restricted to the buffer's size. 3054 * 3055 * This routine is typically called after a read completes. 3056 */ 3057 static void 3058 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m) 3059 { 3060 vm_ooffset_t soff, eoff; 3061 3062 /* 3063 * Start and end offsets in buffer. eoff - soff may not cross a 3064 * page boundry or cross the end of the buffer. The end of the 3065 * buffer, in this case, is our file EOF, not the allocation size 3066 * of the buffer. 3067 */ 3068 soff = off; 3069 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3070 if (eoff > bp->b_loffset + bp->b_bcount) 3071 eoff = bp->b_loffset + bp->b_bcount; 3072 3073 /* 3074 * Set valid range. This is typically the entire buffer and thus the 3075 * entire page. 3076 */ 3077 if (eoff > soff) { 3078 vm_page_set_validclean( 3079 m, 3080 (vm_offset_t) (soff & PAGE_MASK), 3081 (vm_offset_t) (eoff - soff) 3082 ); 3083 } 3084 } 3085 3086 /* 3087 * vfs_busy_pages: 3088 * 3089 * This routine is called before a device strategy routine. 3090 * It is used to tell the VM system that paging I/O is in 3091 * progress, and treat the pages associated with the buffer 3092 * almost as being PG_BUSY. Also the object 'paging_in_progress' 3093 * flag is handled to make sure that the object doesn't become 3094 * inconsistant. 3095 * 3096 * Since I/O has not been initiated yet, certain buffer flags 3097 * such as B_ERROR or B_INVAL may be in an inconsistant state 3098 * and should be ignored. 3099 */ 3100 void 3101 vfs_busy_pages(struct vnode *vp, struct buf *bp) 3102 { 3103 int i, bogus; 3104 struct lwp *lp = curthread->td_lwp; 3105 3106 /* 3107 * The buffer's I/O command must already be set. If reading, 3108 * B_CACHE must be 0 (double check against callers only doing 3109 * I/O when B_CACHE is 0). 3110 */ 3111 KKASSERT(bp->b_cmd != BUF_CMD_DONE); 3112 KKASSERT(bp->b_cmd == BUF_CMD_WRITE || (bp->b_flags & B_CACHE) == 0); 3113 3114 if (bp->b_flags & B_VMIO) { 3115 vm_object_t obj; 3116 vm_ooffset_t foff; 3117 3118 obj = vp->v_object; 3119 foff = bp->b_loffset; 3120 KASSERT(bp->b_loffset != NOOFFSET, 3121 ("vfs_busy_pages: no buffer offset")); 3122 vfs_setdirty(bp); 3123 3124 retry: 3125 for (i = 0; i < bp->b_xio.xio_npages; i++) { 3126 vm_page_t m = bp->b_xio.xio_pages[i]; 3127 if (vm_page_sleep_busy(m, FALSE, "vbpage")) 3128 goto retry; 3129 } 3130 3131 bogus = 0; 3132 for (i = 0; i < bp->b_xio.xio_npages; i++) { 3133 vm_page_t m = bp->b_xio.xio_pages[i]; 3134 3135 vm_page_flag_clear(m, PG_ZERO); 3136 if ((bp->b_flags & B_CLUSTER) == 0) { 3137 vm_object_pip_add(obj, 1); 3138 vm_page_io_start(m); 3139 } 3140 3141 /* 3142 * When readying a vnode-backed buffer for a write 3143 * we must zero-fill any invalid portions of the 3144 * backing VM pages. 3145 * 3146 * When readying a vnode-backed buffer for a read 3147 * we must replace any dirty pages with a bogus 3148 * page so we do not destroy dirty data when 3149 * filling in gaps. Dirty pages might not 3150 * necessarily be marked dirty yet, so use m->valid 3151 * as a reasonable test. 3152 * 3153 * Bogus page replacement is, uh, bogus. We need 3154 * to find a better way. 3155 */ 3156 vm_page_protect(m, VM_PROT_NONE); 3157 if (bp->b_cmd == BUF_CMD_WRITE) { 3158 vfs_page_set_valid(bp, foff, i, m); 3159 } else if (m->valid == VM_PAGE_BITS_ALL) { 3160 bp->b_xio.xio_pages[i] = bogus_page; 3161 bogus++; 3162 } 3163 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3164 } 3165 if (bogus) 3166 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3167 bp->b_xio.xio_pages, bp->b_xio.xio_npages); 3168 } 3169 3170 /* 3171 * This is the easiest place to put the process accounting for the I/O 3172 * for now. 3173 */ 3174 if (lp != NULL) { 3175 if (bp->b_cmd == BUF_CMD_READ) 3176 lp->lwp_ru.ru_inblock++; 3177 else 3178 lp->lwp_ru.ru_oublock++; 3179 } 3180 } 3181 3182 /* 3183 * vfs_clean_pages: 3184 * 3185 * Tell the VM system that the pages associated with this buffer 3186 * are clean. This is used for delayed writes where the data is 3187 * going to go to disk eventually without additional VM intevention. 3188 * 3189 * Note that while we only really need to clean through to b_bcount, we 3190 * just go ahead and clean through to b_bufsize. 3191 */ 3192 static void 3193 vfs_clean_pages(struct buf *bp) 3194 { 3195 int i; 3196 3197 if (bp->b_flags & B_VMIO) { 3198 vm_ooffset_t foff; 3199 3200 foff = bp->b_loffset; 3201 KASSERT(foff != NOOFFSET, ("vfs_clean_pages: no buffer offset")); 3202 for (i = 0; i < bp->b_xio.xio_npages; i++) { 3203 vm_page_t m = bp->b_xio.xio_pages[i]; 3204 vm_ooffset_t noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3205 vm_ooffset_t eoff = noff; 3206 3207 if (eoff > bp->b_loffset + bp->b_bufsize) 3208 eoff = bp->b_loffset + bp->b_bufsize; 3209 vfs_page_set_valid(bp, foff, i, m); 3210 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3211 foff = noff; 3212 } 3213 } 3214 } 3215 3216 /* 3217 * vfs_bio_set_validclean: 3218 * 3219 * Set the range within the buffer to valid and clean. The range is 3220 * relative to the beginning of the buffer, b_loffset. Note that 3221 * b_loffset itself may be offset from the beginning of the first page. 3222 */ 3223 3224 void 3225 vfs_bio_set_validclean(struct buf *bp, int base, int size) 3226 { 3227 if (bp->b_flags & B_VMIO) { 3228 int i; 3229 int n; 3230 3231 /* 3232 * Fixup base to be relative to beginning of first page. 3233 * Set initial n to be the maximum number of bytes in the 3234 * first page that can be validated. 3235 */ 3236 3237 base += (bp->b_loffset & PAGE_MASK); 3238 n = PAGE_SIZE - (base & PAGE_MASK); 3239 3240 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_xio.xio_npages; ++i) { 3241 vm_page_t m = bp->b_xio.xio_pages[i]; 3242 3243 if (n > size) 3244 n = size; 3245 3246 vm_page_set_validclean(m, base & PAGE_MASK, n); 3247 base += n; 3248 size -= n; 3249 n = PAGE_SIZE; 3250 } 3251 } 3252 } 3253 3254 /* 3255 * vfs_bio_clrbuf: 3256 * 3257 * Clear a buffer. This routine essentially fakes an I/O, so we need 3258 * to clear B_ERROR and B_INVAL. 3259 * 3260 * Note that while we only theoretically need to clear through b_bcount, 3261 * we go ahead and clear through b_bufsize. 3262 */ 3263 3264 void 3265 vfs_bio_clrbuf(struct buf *bp) 3266 { 3267 int i, mask = 0; 3268 caddr_t sa, ea; 3269 if ((bp->b_flags & (B_VMIO | B_MALLOC)) == B_VMIO) { 3270 bp->b_flags &= ~(B_INVAL|B_ERROR); 3271 if ((bp->b_xio.xio_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 3272 (bp->b_loffset & PAGE_MASK) == 0) { 3273 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 3274 if ((bp->b_xio.xio_pages[0]->valid & mask) == mask) { 3275 bp->b_resid = 0; 3276 return; 3277 } 3278 if (((bp->b_xio.xio_pages[0]->flags & PG_ZERO) == 0) && 3279 ((bp->b_xio.xio_pages[0]->valid & mask) == 0)) { 3280 bzero(bp->b_data, bp->b_bufsize); 3281 bp->b_xio.xio_pages[0]->valid |= mask; 3282 bp->b_resid = 0; 3283 return; 3284 } 3285 } 3286 ea = sa = bp->b_data; 3287 for(i=0;i<bp->b_xio.xio_npages;i++,sa=ea) { 3288 int j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; 3289 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); 3290 ea = (caddr_t)(vm_offset_t)ulmin( 3291 (u_long)(vm_offset_t)ea, 3292 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); 3293 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 3294 if ((bp->b_xio.xio_pages[i]->valid & mask) == mask) 3295 continue; 3296 if ((bp->b_xio.xio_pages[i]->valid & mask) == 0) { 3297 if ((bp->b_xio.xio_pages[i]->flags & PG_ZERO) == 0) { 3298 bzero(sa, ea - sa); 3299 } 3300 } else { 3301 for (; sa < ea; sa += DEV_BSIZE, j++) { 3302 if (((bp->b_xio.xio_pages[i]->flags & PG_ZERO) == 0) && 3303 (bp->b_xio.xio_pages[i]->valid & (1<<j)) == 0) 3304 bzero(sa, DEV_BSIZE); 3305 } 3306 } 3307 bp->b_xio.xio_pages[i]->valid |= mask; 3308 vm_page_flag_clear(bp->b_xio.xio_pages[i], PG_ZERO); 3309 } 3310 bp->b_resid = 0; 3311 } else { 3312 clrbuf(bp); 3313 } 3314 } 3315 3316 /* 3317 * vm_hold_load_pages: 3318 * 3319 * Load pages into the buffer's address space. The pages are 3320 * allocated from the kernel object in order to reduce interference 3321 * with the any VM paging I/O activity. The range of loaded 3322 * pages will be wired. 3323 * 3324 * If a page cannot be allocated, the 'pagedaemon' is woken up to 3325 * retrieve the full range (to - from) of pages. 3326 * 3327 */ 3328 void 3329 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 3330 { 3331 vm_offset_t pg; 3332 vm_page_t p; 3333 int index; 3334 3335 to = round_page(to); 3336 from = round_page(from); 3337 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3338 3339 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3340 3341 tryagain: 3342 3343 /* 3344 * Note: must allocate system pages since blocking here 3345 * could intefere with paging I/O, no matter which 3346 * process we are. 3347 */ 3348 p = vm_page_alloc(&kernel_object, 3349 (pg >> PAGE_SHIFT), 3350 VM_ALLOC_NORMAL | VM_ALLOC_SYSTEM); 3351 if (!p) { 3352 vm_pageout_deficit += (to - from) >> PAGE_SHIFT; 3353 vm_wait(); 3354 goto tryagain; 3355 } 3356 vm_page_wire(p); 3357 p->valid = VM_PAGE_BITS_ALL; 3358 vm_page_flag_clear(p, PG_ZERO); 3359 pmap_kenter(pg, VM_PAGE_TO_PHYS(p)); 3360 bp->b_xio.xio_pages[index] = p; 3361 vm_page_wakeup(p); 3362 } 3363 bp->b_xio.xio_npages = index; 3364 } 3365 3366 /* 3367 * vm_hold_free_pages: 3368 * 3369 * Return pages associated with the buffer back to the VM system. 3370 * 3371 * The range of pages underlying the buffer's address space will 3372 * be unmapped and un-wired. 3373 */ 3374 void 3375 vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 3376 { 3377 vm_offset_t pg; 3378 vm_page_t p; 3379 int index, newnpages; 3380 3381 from = round_page(from); 3382 to = round_page(to); 3383 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3384 3385 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3386 p = bp->b_xio.xio_pages[index]; 3387 if (p && (index < bp->b_xio.xio_npages)) { 3388 if (p->busy) { 3389 kprintf("vm_hold_free_pages: doffset: %lld, loffset: %lld\n", 3390 bp->b_bio2.bio_offset, bp->b_loffset); 3391 } 3392 bp->b_xio.xio_pages[index] = NULL; 3393 pmap_kremove(pg); 3394 vm_page_busy(p); 3395 vm_page_unwire(p, 0); 3396 vm_page_free(p); 3397 } 3398 } 3399 bp->b_xio.xio_npages = newnpages; 3400 } 3401 3402 /* 3403 * vmapbuf: 3404 * 3405 * Map a user buffer into KVM via a pbuf. On return the buffer's 3406 * b_data, b_bufsize, and b_bcount will be set, and its XIO page array 3407 * initialized. 3408 */ 3409 int 3410 vmapbuf(struct buf *bp, caddr_t udata, int bytes) 3411 { 3412 caddr_t addr; 3413 vm_offset_t va; 3414 vm_page_t m; 3415 int vmprot; 3416 int error; 3417 int pidx; 3418 int i; 3419 3420 /* 3421 * bp had better have a command and it better be a pbuf. 3422 */ 3423 KKASSERT(bp->b_cmd != BUF_CMD_DONE); 3424 KKASSERT(bp->b_flags & B_PAGING); 3425 3426 if (bytes < 0) 3427 return (-1); 3428 3429 /* 3430 * Map the user data into KVM. Mappings have to be page-aligned. 3431 */ 3432 addr = (caddr_t)trunc_page((vm_offset_t)udata); 3433 pidx = 0; 3434 3435 vmprot = VM_PROT_READ; 3436 if (bp->b_cmd == BUF_CMD_READ) 3437 vmprot |= VM_PROT_WRITE; 3438 3439 while (addr < udata + bytes) { 3440 /* 3441 * Do the vm_fault if needed; do the copy-on-write thing 3442 * when reading stuff off device into memory. 3443 * 3444 * vm_fault_page*() returns a held VM page. 3445 */ 3446 va = (addr >= udata) ? (vm_offset_t)addr : (vm_offset_t)udata; 3447 va = trunc_page(va); 3448 3449 m = vm_fault_page_quick(va, vmprot, &error); 3450 if (m == NULL) { 3451 for (i = 0; i < pidx; ++i) { 3452 vm_page_unhold(bp->b_xio.xio_pages[i]); 3453 bp->b_xio.xio_pages[i] = NULL; 3454 } 3455 return(-1); 3456 } 3457 bp->b_xio.xio_pages[pidx] = m; 3458 addr += PAGE_SIZE; 3459 ++pidx; 3460 } 3461 3462 /* 3463 * Map the page array and set the buffer fields to point to 3464 * the mapped data buffer. 3465 */ 3466 if (pidx > btoc(MAXPHYS)) 3467 panic("vmapbuf: mapped more than MAXPHYS"); 3468 pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_xio.xio_pages, pidx); 3469 3470 bp->b_xio.xio_npages = pidx; 3471 bp->b_data = bp->b_kvabase + ((int)(intptr_t)udata & PAGE_MASK); 3472 bp->b_bcount = bytes; 3473 bp->b_bufsize = bytes; 3474 return(0); 3475 } 3476 3477 /* 3478 * vunmapbuf: 3479 * 3480 * Free the io map PTEs associated with this IO operation. 3481 * We also invalidate the TLB entries and restore the original b_addr. 3482 */ 3483 void 3484 vunmapbuf(struct buf *bp) 3485 { 3486 int pidx; 3487 int npages; 3488 3489 KKASSERT(bp->b_flags & B_PAGING); 3490 3491 npages = bp->b_xio.xio_npages; 3492 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 3493 for (pidx = 0; pidx < npages; ++pidx) { 3494 vm_page_unhold(bp->b_xio.xio_pages[pidx]); 3495 bp->b_xio.xio_pages[pidx] = NULL; 3496 } 3497 bp->b_xio.xio_npages = 0; 3498 bp->b_data = bp->b_kvabase; 3499 } 3500 3501 /* 3502 * Scan all buffers in the system and issue the callback. 3503 */ 3504 int 3505 scan_all_buffers(int (*callback)(struct buf *, void *), void *info) 3506 { 3507 int count = 0; 3508 int error; 3509 int n; 3510 3511 for (n = 0; n < nbuf; ++n) { 3512 if ((error = callback(&buf[n], info)) < 0) { 3513 count = error; 3514 break; 3515 } 3516 count += error; 3517 } 3518 return (count); 3519 } 3520 3521 /* 3522 * print out statistics from the current status of the buffer pool 3523 * this can be toggeled by the system control option debug.syncprt 3524 */ 3525 #ifdef DEBUG 3526 void 3527 vfs_bufstats(void) 3528 { 3529 int i, j, count; 3530 struct buf *bp; 3531 struct bqueues *dp; 3532 int counts[(MAXBSIZE / PAGE_SIZE) + 1]; 3533 static char *bname[3] = { "LOCKED", "LRU", "AGE" }; 3534 3535 for (dp = bufqueues, i = 0; dp < &bufqueues[3]; dp++, i++) { 3536 count = 0; 3537 for (j = 0; j <= MAXBSIZE/PAGE_SIZE; j++) 3538 counts[j] = 0; 3539 crit_enter(); 3540 TAILQ_FOREACH(bp, dp, b_freelist) { 3541 counts[bp->b_bufsize/PAGE_SIZE]++; 3542 count++; 3543 } 3544 crit_exit(); 3545 kprintf("%s: total-%d", bname[i], count); 3546 for (j = 0; j <= MAXBSIZE/PAGE_SIZE; j++) 3547 if (counts[j] != 0) 3548 kprintf(", %d-%d", j * PAGE_SIZE, counts[j]); 3549 kprintf("\n"); 3550 } 3551 } 3552 #endif 3553 3554 #ifdef DDB 3555 3556 DB_SHOW_COMMAND(buffer, db_show_buffer) 3557 { 3558 /* get args */ 3559 struct buf *bp = (struct buf *)addr; 3560 3561 if (!have_addr) { 3562 db_printf("usage: show buffer <addr>\n"); 3563 return; 3564 } 3565 3566 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS); 3567 db_printf("b_cmd = %d\n", bp->b_cmd); 3568 db_printf("b_error = %d, b_bufsize = %d, b_bcount = %d, " 3569 "b_resid = %d\n, b_data = %p, " 3570 "bio_offset(disk) = %lld, bio_offset(phys) = %lld\n", 3571 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 3572 bp->b_data, bp->b_bio2.bio_offset, (bp->b_bio2.bio_next ? bp->b_bio2.bio_next->bio_offset : (off_t)-1)); 3573 if (bp->b_xio.xio_npages) { 3574 int i; 3575 db_printf("b_xio.xio_npages = %d, pages(OBJ, IDX, PA): ", 3576 bp->b_xio.xio_npages); 3577 for (i = 0; i < bp->b_xio.xio_npages; i++) { 3578 vm_page_t m; 3579 m = bp->b_xio.xio_pages[i]; 3580 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 3581 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 3582 if ((i + 1) < bp->b_xio.xio_npages) 3583 db_printf(","); 3584 } 3585 db_printf("\n"); 3586 } 3587 } 3588 #endif /* DDB */ 3589