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 1.46 2005/08/08 01:25:31 hmp 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 <vm/vm_page2.h> 60 61 /* 62 * Buffer queues. 63 */ 64 #define BUFFER_QUEUES 6 65 enum bufq_type { 66 BQUEUE_NONE, /* not on any queue */ 67 BQUEUE_LOCKED, /* locked buffers */ 68 BQUEUE_CLEAN, /* non-B_DELWRI buffers */ 69 BQUEUE_DIRTY, /* B_DELWRI buffers */ 70 BQUEUE_EMPTYKVA, /* empty buffer headers with KVA assignment */ 71 BQUEUE_EMPTY /* empty buffer headers */ 72 }; 73 TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES]; 74 75 static MALLOC_DEFINE(M_BIOBUF, "BIO buffer", "BIO buffer"); 76 77 struct bio_ops bioops; /* I/O operation notification */ 78 79 struct buf *buf; /* buffer header pool */ 80 struct swqueue bswlist; 81 82 static void vm_hold_free_pages(struct buf * bp, vm_offset_t from, 83 vm_offset_t to); 84 static void vm_hold_load_pages(struct buf * bp, vm_offset_t from, 85 vm_offset_t to); 86 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, 87 int pageno, vm_page_t m); 88 static void vfs_clean_pages(struct buf * bp); 89 static void vfs_setdirty(struct buf *bp); 90 static void vfs_vmio_release(struct buf *bp); 91 #if 0 92 static void vfs_backgroundwritedone(struct buf *bp); 93 #endif 94 static int flushbufqueues(void); 95 96 static int bd_request; 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 vmiodirenable = TRUE; 108 int runningbufspace; 109 struct lwkt_token buftimetoken; /* Interlock on setting prio and timo */ 110 111 static int bufspace, maxbufspace, 112 bufmallocspace, maxbufmallocspace, lobufspace, hibufspace; 113 static int bufreusecnt, bufdefragcnt, buffreekvacnt; 114 static int needsbuffer; 115 static int lorunningspace, hirunningspace, runningbufreq; 116 static int numdirtybuffers, lodirtybuffers, hidirtybuffers; 117 static int numfreebuffers, lofreebuffers, hifreebuffers; 118 static int getnewbufcalls; 119 static int getnewbufrestarts; 120 121 /* 122 * Sysctls for operational control of the buffer cache. 123 */ 124 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0, 125 "Number of dirty buffers to flush before bufdaemon becomes inactive"); 126 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0, 127 "High water mark used to trigger explicit flushing of dirty buffers"); 128 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0, 129 "Low watermark for calculating special reserve in low-memory situations"); 130 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0, 131 "High watermark for calculating special reserve in low-memory situations"); 132 SYSCTL_INT(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0, 133 "Minimum amount of buffer space required for active I/O"); 134 SYSCTL_INT(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0, 135 "Maximum amount of buffer space to usable for active I/O"); 136 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, 137 "Use the VM system for performing directory writes"); 138 /* 139 * Sysctls determining current state of the buffer cache. 140 */ 141 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0, 142 "Pending number of dirty buffers"); 143 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, 144 "Number of free buffers on the buffer cache free list"); 145 SYSCTL_INT(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 146 "Amount of I/O bytes currently in progress due to asynchronous writes"); 147 SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0, 148 "Hard limit on maximum amount of memory usable for buffer space"); 149 SYSCTL_INT(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0, 150 "Soft limit on maximum amount of memory usable for buffer space"); 151 SYSCTL_INT(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0, 152 "Minimum amount of memory to reserve for system buffer space"); 153 SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, 154 "Amount of memory available for buffers"); 155 SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RD, &maxbufmallocspace, 156 0, "Maximum amount of memory reserved for buffers using malloc-scheme"); 157 SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 158 "Amount of memory left for buffers using malloc-scheme"); 159 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RD, &getnewbufcalls, 0, 160 "New buffer header acquisition requests"); 161 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RD, &getnewbufrestarts, 162 0, "New buffer header acquisition restarts"); 163 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RD, &bufdefragcnt, 0, 164 "Amount of time buffer acquisition restarted due to fragmented buffer map"); 165 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RD, &buffreekvacnt, 0, 166 "Amount of time KVA space was deallocated in an arbitrary buffer"); 167 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RD, &bufreusecnt, 0, 168 "Amount of time buffer re-use operations were successful"); 169 SYSCTL_INT(_debug_sizeof, OID_AUTO, buf, CTLFLAG_RD, 0, sizeof(struct buf), 170 "sizeof(struct buf)"); 171 172 #if 0 173 /* 174 * Disable background writes for now. There appear to be races in the 175 * flags tests and locking operations as well as races in the completion 176 * code modifying the original bp (origbp) without holding a lock, assuming 177 * critical section protection when there might not be critical section 178 * protection. 179 * 180 * XXX disable also because the RB tree can't handle multiple blocks with 181 * the same lblkno. 182 */ 183 static int dobkgrdwrite = 0; 184 SYSCTL_INT(_debug, OID_AUTO, dobkgrdwrite, CTLFLAG_RW, &dobkgrdwrite, 0, 185 "Do background writes (honoring the BV_BKGRDWRITE flag)?"); 186 #endif 187 188 static int bufhashmask; 189 static int bufhashshift; 190 static LIST_HEAD(bufhashhdr, buf) *bufhashtbl, invalhash; 191 char *buf_wmesg = BUF_WMESG; 192 193 extern int vm_swap_size; 194 195 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 196 #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */ 197 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ 198 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 199 200 /* 201 * Buffer hash table code. Note that the logical block scans linearly, which 202 * gives us some L1 cache locality. 203 */ 204 205 static __inline 206 struct bufhashhdr * 207 bufhash(struct vnode *vnp, daddr_t bn) 208 { 209 u_int64_t hashkey64; 210 int hashkey; 211 212 /* 213 * A variation on the Fibonacci hash that Knuth credits to 214 * R. W. Floyd, see Knuth's _Art of Computer Programming, 215 * Volume 3 / Sorting and Searching_ 216 * 217 * We reduce the argument to 32 bits before doing the hash to 218 * avoid the need for a slow 64x64 multiply on 32 bit platforms. 219 * 220 * sizeof(struct vnode) is 168 on i386, so toss some of the lower 221 * bits of the vnode address to reduce the key range, which 222 * improves the distribution of keys across buckets. 223 * 224 * The file system cylinder group blocks are very heavily 225 * used. They are located at invervals of fbg, which is 226 * on the order of 89 to 94 * 2^10, depending on other 227 * filesystem parameters, for a 16k block size. Smaller block 228 * sizes will reduce fpg approximately proportionally. This 229 * will cause the cylinder group index to be hashed using the 230 * lower bits of the hash multiplier, which will not distribute 231 * the keys as uniformly in a classic Fibonacci hash where a 232 * relatively small number of the upper bits of the result 233 * are used. Using 2^16 as a close-enough approximation to 234 * fpg, split the hash multiplier in half, with the upper 16 235 * bits being the inverse of the golden ratio, and the lower 236 * 16 bits being a fraction between 1/3 and 3/7 (closer to 237 * 3/7 in this case), that gives good experimental results. 238 */ 239 hashkey64 = ((u_int64_t)(uintptr_t)vnp >> 3) + (u_int64_t)bn; 240 hashkey = (((u_int32_t)(hashkey64 + (hashkey64 >> 32)) * 0x9E376DB1u) >> 241 bufhashshift) & bufhashmask; 242 return(&bufhashtbl[hashkey]); 243 } 244 245 /* 246 * numdirtywakeup: 247 * 248 * If someone is blocked due to there being too many dirty buffers, 249 * and numdirtybuffers is now reasonable, wake them up. 250 */ 251 252 static __inline void 253 numdirtywakeup(int level) 254 { 255 if (numdirtybuffers <= level) { 256 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) { 257 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH; 258 wakeup(&needsbuffer); 259 } 260 } 261 } 262 263 /* 264 * bufspacewakeup: 265 * 266 * Called when buffer space is potentially available for recovery. 267 * getnewbuf() will block on this flag when it is unable to free 268 * sufficient buffer space. Buffer space becomes recoverable when 269 * bp's get placed back in the queues. 270 */ 271 272 static __inline void 273 bufspacewakeup(void) 274 { 275 /* 276 * If someone is waiting for BUF space, wake them up. Even 277 * though we haven't freed the kva space yet, the waiting 278 * process will be able to now. 279 */ 280 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) { 281 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE; 282 wakeup(&needsbuffer); 283 } 284 } 285 286 /* 287 * runningbufwakeup: 288 * 289 * Accounting for I/O in progress. 290 * 291 */ 292 static __inline void 293 runningbufwakeup(struct buf *bp) 294 { 295 if (bp->b_runningbufspace) { 296 runningbufspace -= bp->b_runningbufspace; 297 bp->b_runningbufspace = 0; 298 if (runningbufreq && runningbufspace <= lorunningspace) { 299 runningbufreq = 0; 300 wakeup(&runningbufreq); 301 } 302 } 303 } 304 305 /* 306 * bufcountwakeup: 307 * 308 * Called when a buffer has been added to one of the free queues to 309 * account for the buffer and to wakeup anyone waiting for free buffers. 310 * This typically occurs when large amounts of metadata are being handled 311 * by the buffer cache ( else buffer space runs out first, usually ). 312 */ 313 314 static __inline void 315 bufcountwakeup(void) 316 { 317 ++numfreebuffers; 318 if (needsbuffer) { 319 needsbuffer &= ~VFS_BIO_NEED_ANY; 320 if (numfreebuffers >= hifreebuffers) 321 needsbuffer &= ~VFS_BIO_NEED_FREE; 322 wakeup(&needsbuffer); 323 } 324 } 325 326 /* 327 * waitrunningbufspace() 328 * 329 * runningbufspace is a measure of the amount of I/O currently 330 * running. This routine is used in async-write situations to 331 * prevent creating huge backups of pending writes to a device. 332 * Only asynchronous writes are governed by this function. 333 * 334 * Reads will adjust runningbufspace, but will not block based on it. 335 * The read load has a side effect of reducing the allowed write load. 336 * 337 * This does NOT turn an async write into a sync write. It waits 338 * for earlier writes to complete and generally returns before the 339 * caller's write has reached the device. 340 */ 341 static __inline void 342 waitrunningbufspace(void) 343 { 344 if (runningbufspace > hirunningspace) { 345 crit_enter(); 346 while (runningbufspace > hirunningspace) { 347 ++runningbufreq; 348 tsleep(&runningbufreq, 0, "wdrain", 0); 349 } 350 crit_exit(); 351 } 352 } 353 354 /* 355 * vfs_buf_test_cache: 356 * 357 * Called when a buffer is extended. This function clears the B_CACHE 358 * bit if the newly extended portion of the buffer does not contain 359 * valid data. 360 */ 361 static __inline__ 362 void 363 vfs_buf_test_cache(struct buf *bp, 364 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 365 vm_page_t m) 366 { 367 if (bp->b_flags & B_CACHE) { 368 int base = (foff + off) & PAGE_MASK; 369 if (vm_page_is_valid(m, base, size) == 0) 370 bp->b_flags &= ~B_CACHE; 371 } 372 } 373 374 /* 375 * bd_wakeup: 376 * 377 * Wake up the buffer daemon if the number of outstanding dirty buffers 378 * is above specified threshold 'dirtybuflevel'. 379 * 380 * The buffer daemon is explicitly woken up when (a) the pending number 381 * of dirty buffers exceeds the recovery and stall mid-point value, 382 * (b) during bwillwrite() or (c) buf freelist was exhausted. 383 */ 384 static __inline__ 385 void 386 bd_wakeup(int dirtybuflevel) 387 { 388 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) { 389 bd_request = 1; 390 wakeup(&bd_request); 391 } 392 } 393 394 /* 395 * bd_speedup: 396 * 397 * Speed up the buffer cache flushing process. 398 */ 399 400 static __inline__ 401 void 402 bd_speedup(void) 403 { 404 bd_wakeup(1); 405 } 406 407 /* 408 * bufhashinit: 409 * 410 * Initialize buffer headers and related structures. 411 */ 412 413 caddr_t 414 bufhashinit(caddr_t vaddr) 415 { 416 /* first, make a null hash table */ 417 bufhashshift = 29; 418 for (bufhashmask = 8; bufhashmask < nbuf / 4; bufhashmask <<= 1) 419 bufhashshift--; 420 bufhashtbl = (void *)vaddr; 421 vaddr = vaddr + sizeof(*bufhashtbl) * bufhashmask; 422 --bufhashmask; 423 return(vaddr); 424 } 425 426 /* 427 * bufinit: 428 * 429 * Load time initialisation of the buffer cache, called from machine 430 * dependant initialization code. 431 */ 432 void 433 bufinit(void) 434 { 435 struct buf *bp; 436 vm_offset_t bogus_offset; 437 int i; 438 439 TAILQ_INIT(&bswlist); 440 LIST_INIT(&invalhash); 441 lwkt_token_init(&buftimetoken); 442 443 for (i = 0; i <= bufhashmask; i++) 444 LIST_INIT(&bufhashtbl[i]); 445 446 /* next, make a null set of free lists */ 447 for (i = 0; i < BUFFER_QUEUES; i++) 448 TAILQ_INIT(&bufqueues[i]); 449 450 /* finally, initialize each buffer header and stick on empty q */ 451 for (i = 0; i < nbuf; i++) { 452 bp = &buf[i]; 453 bzero(bp, sizeof *bp); 454 bp->b_bio.bio_buf = bp; /* back pointer (temporary) */ 455 bp->b_flags = B_INVAL; /* we're just an empty header */ 456 bp->b_dev = NODEV; 457 bp->b_qindex = BQUEUE_EMPTY; 458 bp->b_xflags = 0; 459 bp->b_iodone = NULL; 460 xio_init(&bp->b_xio); 461 LIST_INIT(&bp->b_dep); 462 BUF_LOCKINIT(bp); 463 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_EMPTY], bp, b_freelist); 464 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 465 } 466 467 /* 468 * maxbufspace is the absolute maximum amount of buffer space we are 469 * allowed to reserve in KVM and in real terms. The absolute maximum 470 * is nominally used by buf_daemon. hibufspace is the nominal maximum 471 * used by most other processes. The differential is required to 472 * ensure that buf_daemon is able to run when other processes might 473 * be blocked waiting for buffer space. 474 * 475 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 476 * this may result in KVM fragmentation which is not handled optimally 477 * by the system. 478 */ 479 maxbufspace = nbuf * BKVASIZE; 480 hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 481 lobufspace = hibufspace - MAXBSIZE; 482 483 lorunningspace = 512 * 1024; 484 hirunningspace = 1024 * 1024; 485 486 /* 487 * Limit the amount of malloc memory since it is wired permanently into 488 * the kernel space. Even though this is accounted for in the buffer 489 * allocation, we don't want the malloced region to grow uncontrolled. 490 * The malloc scheme improves memory utilization significantly on average 491 * (small) directories. 492 */ 493 maxbufmallocspace = hibufspace / 20; 494 495 /* 496 * Reduce the chance of a deadlock occuring by limiting the number 497 * of delayed-write dirty buffers we allow to stack up. 498 */ 499 hidirtybuffers = nbuf / 4 + 20; 500 numdirtybuffers = 0; 501 /* 502 * To support extreme low-memory systems, make sure hidirtybuffers cannot 503 * eat up all available buffer space. This occurs when our minimum cannot 504 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 505 * BKVASIZE'd (8K) buffers. 506 */ 507 while (hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 508 hidirtybuffers >>= 1; 509 } 510 lodirtybuffers = hidirtybuffers / 2; 511 512 /* 513 * Try to keep the number of free buffers in the specified range, 514 * and give special processes (e.g. like buf_daemon) access to an 515 * emergency reserve. 516 */ 517 lofreebuffers = nbuf / 18 + 5; 518 hifreebuffers = 2 * lofreebuffers; 519 numfreebuffers = nbuf; 520 521 /* 522 * Maximum number of async ops initiated per buf_daemon loop. This is 523 * somewhat of a hack at the moment, we really need to limit ourselves 524 * based on the number of bytes of I/O in-transit that were initiated 525 * from buf_daemon. 526 */ 527 528 bogus_offset = kmem_alloc_pageable(kernel_map, PAGE_SIZE); 529 bogus_page = vm_page_alloc(kernel_object, 530 ((bogus_offset - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 531 VM_ALLOC_NORMAL); 532 vmstats.v_wire_count++; 533 534 } 535 536 /* 537 * bfreekva: 538 * 539 * Free the KVA allocation for buffer 'bp'. 540 * 541 * Must be called from a critical section as this is the only locking for 542 * buffer_map. 543 * 544 * Since this call frees up buffer space, we call bufspacewakeup(). 545 */ 546 static void 547 bfreekva(struct buf * bp) 548 { 549 int count; 550 551 if (bp->b_kvasize) { 552 ++buffreekvacnt; 553 count = vm_map_entry_reserve(MAP_RESERVE_COUNT); 554 vm_map_lock(buffer_map); 555 bufspace -= bp->b_kvasize; 556 vm_map_delete(buffer_map, 557 (vm_offset_t) bp->b_kvabase, 558 (vm_offset_t) bp->b_kvabase + bp->b_kvasize, 559 &count 560 ); 561 vm_map_unlock(buffer_map); 562 vm_map_entry_release(count); 563 bp->b_kvasize = 0; 564 bufspacewakeup(); 565 } 566 } 567 568 /* 569 * bremfree: 570 * 571 * Remove the buffer from the appropriate free list. 572 */ 573 void 574 bremfree(struct buf * bp) 575 { 576 int old_qindex; 577 578 crit_enter(); 579 old_qindex = bp->b_qindex; 580 581 if (bp->b_qindex != BQUEUE_NONE) { 582 KASSERT(BUF_REFCNTNB(bp) == 1, 583 ("bremfree: bp %p not locked",bp)); 584 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 585 bp->b_qindex = BQUEUE_NONE; 586 } else { 587 if (BUF_REFCNTNB(bp) <= 1) 588 panic("bremfree: removing a buffer not on a queue"); 589 } 590 591 /* 592 * Fixup numfreebuffers count. If the buffer is invalid or not 593 * delayed-write, and it was on the EMPTY, LRU, or AGE queues, 594 * the buffer was free and we must decrement numfreebuffers. 595 */ 596 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { 597 switch(old_qindex) { 598 case BQUEUE_DIRTY: 599 case BQUEUE_CLEAN: 600 case BQUEUE_EMPTY: 601 case BQUEUE_EMPTYKVA: 602 --numfreebuffers; 603 break; 604 default: 605 break; 606 } 607 } 608 crit_exit(); 609 } 610 611 612 /* 613 * bread: 614 * 615 * Get a buffer with the specified data. Look in the cache first. We 616 * must clear B_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 617 * is set, the buffer is valid and we do not have to do anything ( see 618 * getblk() ). 619 */ 620 int 621 bread(struct vnode * vp, daddr_t blkno, int size, struct buf ** bpp) 622 { 623 struct buf *bp; 624 625 bp = getblk(vp, blkno, size, 0, 0); 626 *bpp = bp; 627 628 /* if not found in cache, do some I/O */ 629 if ((bp->b_flags & B_CACHE) == 0) { 630 KASSERT(!(bp->b_flags & B_ASYNC), ("bread: illegal async bp %p", bp)); 631 bp->b_flags |= B_READ; 632 bp->b_flags &= ~(B_ERROR | B_INVAL); 633 vfs_busy_pages(bp, 0); 634 VOP_STRATEGY(vp, bp); 635 return (biowait(bp)); 636 } 637 return (0); 638 } 639 640 /* 641 * breadn: 642 * 643 * Operates like bread, but also starts asynchronous I/O on 644 * read-ahead blocks. We must clear B_ERROR and B_INVAL prior 645 * to initiating I/O . If B_CACHE is set, the buffer is valid 646 * and we do not have to do anything. 647 */ 648 int 649 breadn(struct vnode * vp, daddr_t blkno, int size, daddr_t * rablkno, 650 int *rabsize, int cnt, struct buf ** bpp) 651 { 652 struct buf *bp, *rabp; 653 int i; 654 int rv = 0, readwait = 0; 655 656 *bpp = bp = getblk(vp, blkno, size, 0, 0); 657 658 /* if not found in cache, do some I/O */ 659 if ((bp->b_flags & B_CACHE) == 0) { 660 bp->b_flags |= B_READ; 661 bp->b_flags &= ~(B_ERROR | B_INVAL); 662 vfs_busy_pages(bp, 0); 663 VOP_STRATEGY(vp, bp); 664 ++readwait; 665 } 666 667 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 668 if (inmem(vp, *rablkno)) 669 continue; 670 rabp = getblk(vp, *rablkno, *rabsize, 0, 0); 671 672 if ((rabp->b_flags & B_CACHE) == 0) { 673 rabp->b_flags |= B_READ | B_ASYNC; 674 rabp->b_flags &= ~(B_ERROR | B_INVAL); 675 vfs_busy_pages(rabp, 0); 676 BUF_KERNPROC(rabp); 677 VOP_STRATEGY(vp, rabp); 678 } else { 679 brelse(rabp); 680 } 681 } 682 683 if (readwait) { 684 rv = biowait(bp); 685 } 686 return (rv); 687 } 688 689 /* 690 * bwrite: 691 * 692 * Write, release buffer on completion. (Done by iodone 693 * if async). Do not bother writing anything if the buffer 694 * is invalid. 695 * 696 * Note that we set B_CACHE here, indicating that buffer is 697 * fully valid and thus cacheable. This is true even of NFS 698 * now so we set it generally. This could be set either here 699 * or in biodone() since the I/O is synchronous. We put it 700 * here. 701 */ 702 int 703 bwrite(struct buf * bp) 704 { 705 int oldflags; 706 #if 0 707 struct buf *newbp; 708 #endif 709 710 if (bp->b_flags & B_INVAL) { 711 brelse(bp); 712 return (0); 713 } 714 715 oldflags = bp->b_flags; 716 717 if (BUF_REFCNTNB(bp) == 0) 718 panic("bwrite: buffer is not busy???"); 719 crit_enter(); 720 /* 721 * If a background write is already in progress, delay 722 * writing this block if it is asynchronous. Otherwise 723 * wait for the background write to complete. 724 */ 725 if (bp->b_xflags & BX_BKGRDINPROG) { 726 if (bp->b_flags & B_ASYNC) { 727 crit_exit(); 728 bdwrite(bp); 729 return (0); 730 } 731 bp->b_xflags |= BX_BKGRDWAIT; 732 tsleep(&bp->b_xflags, 0, "biord", 0); 733 if (bp->b_xflags & BX_BKGRDINPROG) 734 panic("bwrite: still writing"); 735 } 736 737 /* Mark the buffer clean */ 738 bundirty(bp); 739 740 #if 0 741 /* 742 * If this buffer is marked for background writing and we 743 * do not have to wait for it, make a copy and write the 744 * copy so as to leave this buffer ready for further use. 745 * 746 * This optimization eats a lot of memory. If we have a page 747 * or buffer shortfull we can't do it. 748 * 749 * XXX DISABLED! This had to be removed to support the RB_TREE 750 * work and, really, this isn't the best place to do this sort 751 * of thing anyway. We really need a device copy-on-write feature. 752 */ 753 if (dobkgrdwrite && 754 (bp->b_xflags & BX_BKGRDWRITE) && 755 (bp->b_flags & B_ASYNC) && 756 !vm_page_count_severe() && 757 !buf_dirty_count_severe()) { 758 if (bp->b_iodone) 759 panic("bwrite: need chained iodone"); 760 761 /* get a new block */ 762 newbp = geteblk(bp->b_bufsize); 763 764 /* set it to be identical to the old block */ 765 memcpy(newbp->b_data, bp->b_data, bp->b_bufsize); 766 newbp->b_lblkno = bp->b_lblkno; 767 newbp->b_blkno = bp->b_blkno; 768 newbp->b_offset = bp->b_offset; 769 newbp->b_iodone = vfs_backgroundwritedone; 770 newbp->b_flags |= B_ASYNC; 771 newbp->b_flags &= ~B_INVAL; 772 bgetvp(bp->b_vp, newbp); 773 774 /* move over the dependencies */ 775 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_movedeps) 776 (*bioops.io_movedeps)(bp, newbp); 777 778 /* 779 * Initiate write on the copy, release the original to 780 * the B_LOCKED queue so that it cannot go away until 781 * the background write completes. If not locked it could go 782 * away and then be reconstituted while it was being written. 783 * If the reconstituted buffer were written, we could end up 784 * with two background copies being written at the same time. 785 */ 786 bp->b_xflags |= BX_BKGRDINPROG; 787 bp->b_flags |= B_LOCKED; 788 bqrelse(bp); 789 bp = newbp; 790 } 791 #endif 792 793 bp->b_flags &= ~(B_READ | B_DONE | B_ERROR); 794 bp->b_flags |= B_CACHE; 795 796 bp->b_vp->v_numoutput++; 797 vfs_busy_pages(bp, 1); 798 799 /* 800 * Normal bwrites pipeline writes 801 */ 802 bp->b_runningbufspace = bp->b_bufsize; 803 runningbufspace += bp->b_runningbufspace; 804 805 crit_exit(); 806 if (oldflags & B_ASYNC) 807 BUF_KERNPROC(bp); 808 VOP_STRATEGY(bp->b_vp, bp); 809 810 if ((oldflags & B_ASYNC) == 0) { 811 int rtval = biowait(bp); 812 brelse(bp); 813 return (rtval); 814 } else if ((oldflags & B_NOWDRAIN) == 0) { 815 /* 816 * don't allow the async write to saturate the I/O 817 * system. Deadlocks can occur only if a device strategy 818 * routine (like in VN) turns around and issues another 819 * high-level write, in which case B_NOWDRAIN is expected 820 * to be set. Otherwise we will not deadlock here because 821 * we are blocking waiting for I/O that is already in-progress 822 * to complete. 823 */ 824 waitrunningbufspace(); 825 } 826 827 return (0); 828 } 829 830 #if 0 831 /* 832 * Complete a background write started from bwrite. 833 */ 834 static void 835 vfs_backgroundwritedone(struct buf *bp) 836 { 837 struct buf *origbp; 838 839 /* 840 * Find the original buffer that we are writing. 841 */ 842 if ((origbp = gbincore(bp->b_vp, bp->b_lblkno)) == NULL) 843 panic("backgroundwritedone: lost buffer"); 844 /* 845 * Process dependencies then return any unfinished ones. 846 */ 847 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_complete) 848 (*bioops.io_complete)(bp); 849 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_movedeps) 850 (*bioops.io_movedeps)(bp, origbp); 851 /* 852 * Clear the BX_BKGRDINPROG flag in the original buffer 853 * and awaken it if it is waiting for the write to complete. 854 * If BX_BKGRDINPROG is not set in the original buffer it must 855 * have been released and re-instantiated - which is not legal. 856 */ 857 KASSERT((origbp->b_xflags & BX_BKGRDINPROG), ("backgroundwritedone: lost buffer2")); 858 origbp->b_xflags &= ~BX_BKGRDINPROG; 859 if (origbp->b_xflags & BX_BKGRDWAIT) { 860 origbp->b_xflags &= ~BX_BKGRDWAIT; 861 wakeup(&origbp->b_xflags); 862 } 863 /* 864 * Clear the B_LOCKED flag and remove it from the locked 865 * queue if it currently resides there. 866 */ 867 origbp->b_flags &= ~B_LOCKED; 868 if (BUF_LOCK(origbp, LK_EXCLUSIVE | LK_NOWAIT) == 0) { 869 bremfree(origbp); 870 bqrelse(origbp); 871 } 872 /* 873 * This buffer is marked B_NOCACHE, so when it is released 874 * by biodone, it will be tossed. We mark it with B_READ 875 * to avoid biodone doing a second vwakeup. 876 */ 877 bp->b_flags |= B_NOCACHE | B_READ; 878 bp->b_flags &= ~(B_CACHE | B_DONE); 879 bp->b_iodone = NULL; 880 biodone(bp); 881 } 882 #endif 883 884 /* 885 * bdwrite: 886 * 887 * Delayed write. (Buffer is marked dirty). Do not bother writing 888 * anything if the buffer is marked invalid. 889 * 890 * Note that since the buffer must be completely valid, we can safely 891 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 892 * biodone() in order to prevent getblk from writing the buffer 893 * out synchronously. 894 */ 895 void 896 bdwrite(struct buf *bp) 897 { 898 if (BUF_REFCNTNB(bp) == 0) 899 panic("bdwrite: buffer is not busy"); 900 901 if (bp->b_flags & B_INVAL) { 902 brelse(bp); 903 return; 904 } 905 bdirty(bp); 906 907 /* 908 * Set B_CACHE, indicating that the buffer is fully valid. This is 909 * true even of NFS now. 910 */ 911 bp->b_flags |= B_CACHE; 912 913 /* 914 * This bmap keeps the system from needing to do the bmap later, 915 * perhaps when the system is attempting to do a sync. Since it 916 * is likely that the indirect block -- or whatever other datastructure 917 * that the filesystem needs is still in memory now, it is a good 918 * thing to do this. Note also, that if the pageout daemon is 919 * requesting a sync -- there might not be enough memory to do 920 * the bmap then... So, this is important to do. 921 */ 922 if (bp->b_lblkno == bp->b_blkno) { 923 VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 924 } 925 926 /* 927 * Set the *dirty* buffer range based upon the VM system dirty pages. 928 */ 929 vfs_setdirty(bp); 930 931 /* 932 * We need to do this here to satisfy the vnode_pager and the 933 * pageout daemon, so that it thinks that the pages have been 934 * "cleaned". Note that since the pages are in a delayed write 935 * buffer -- the VFS layer "will" see that the pages get written 936 * out on the next sync, or perhaps the cluster will be completed. 937 */ 938 vfs_clean_pages(bp); 939 bqrelse(bp); 940 941 /* 942 * Wakeup the buffer flushing daemon if we have a lot of dirty 943 * buffers (midpoint between our recovery point and our stall 944 * point). 945 */ 946 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 947 948 /* 949 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 950 * due to the softdep code. 951 */ 952 } 953 954 /* 955 * bdirty: 956 * 957 * Turn buffer into delayed write request. We must clear B_READ and 958 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 959 * itself to properly update it in the dirty/clean lists. We mark it 960 * B_DONE to ensure that any asynchronization of the buffer properly 961 * clears B_DONE ( else a panic will occur later ). 962 * 963 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 964 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 965 * should only be called if the buffer is known-good. 966 * 967 * Since the buffer is not on a queue, we do not update the numfreebuffers 968 * count. 969 * 970 * Must be called from a critical section. 971 * The buffer must be on BQUEUE_NONE. 972 */ 973 void 974 bdirty(struct buf *bp) 975 { 976 KASSERT(bp->b_qindex == BQUEUE_NONE, ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 977 bp->b_flags &= ~(B_READ|B_RELBUF); 978 979 if ((bp->b_flags & B_DELWRI) == 0) { 980 bp->b_flags |= B_DONE | B_DELWRI; 981 reassignbuf(bp, bp->b_vp); 982 ++numdirtybuffers; 983 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 984 } 985 } 986 987 /* 988 * bundirty: 989 * 990 * Clear B_DELWRI for buffer. 991 * 992 * Since the buffer is not on a queue, we do not update the numfreebuffers 993 * count. 994 * 995 * Must be called from a critical section. 996 * 997 * The buffer is typically on BQUEUE_NONE but there is one case in 998 * brelse() that calls this function after placing the buffer on 999 * a different queue. 1000 */ 1001 1002 void 1003 bundirty(struct buf *bp) 1004 { 1005 if (bp->b_flags & B_DELWRI) { 1006 bp->b_flags &= ~B_DELWRI; 1007 reassignbuf(bp, bp->b_vp); 1008 --numdirtybuffers; 1009 numdirtywakeup(lodirtybuffers); 1010 } 1011 /* 1012 * Since it is now being written, we can clear its deferred write flag. 1013 */ 1014 bp->b_flags &= ~B_DEFERRED; 1015 } 1016 1017 /* 1018 * bawrite: 1019 * 1020 * Asynchronous write. Start output on a buffer, but do not wait for 1021 * it to complete. The buffer is released when the output completes. 1022 * 1023 * bwrite() ( or the VOP routine anyway ) is responsible for handling 1024 * B_INVAL buffers. Not us. 1025 */ 1026 void 1027 bawrite(struct buf * bp) 1028 { 1029 bp->b_flags |= B_ASYNC; 1030 (void) VOP_BWRITE(bp->b_vp, bp); 1031 } 1032 1033 /* 1034 * bowrite: 1035 * 1036 * Ordered write. Start output on a buffer, and flag it so that the 1037 * device will write it in the order it was queued. The buffer is 1038 * released when the output completes. bwrite() ( or the VOP routine 1039 * anyway ) is responsible for handling B_INVAL buffers. 1040 */ 1041 int 1042 bowrite(struct buf * bp) 1043 { 1044 bp->b_flags |= B_ORDERED | B_ASYNC; 1045 return (VOP_BWRITE(bp->b_vp, bp)); 1046 } 1047 1048 /* 1049 * bwillwrite: 1050 * 1051 * Called prior to the locking of any vnodes when we are expecting to 1052 * write. We do not want to starve the buffer cache with too many 1053 * dirty buffers so we block here. By blocking prior to the locking 1054 * of any vnodes we attempt to avoid the situation where a locked vnode 1055 * prevents the various system daemons from flushing related buffers. 1056 */ 1057 1058 void 1059 bwillwrite(void) 1060 { 1061 if (numdirtybuffers >= hidirtybuffers) { 1062 crit_enter(); 1063 while (numdirtybuffers >= hidirtybuffers) { 1064 bd_wakeup(1); 1065 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH; 1066 tsleep(&needsbuffer, 0, "flswai", 0); 1067 } 1068 crit_exit(); 1069 } 1070 } 1071 1072 /* 1073 * buf_dirty_count_severe: 1074 * 1075 * Return true if we have too many dirty buffers. 1076 */ 1077 int 1078 buf_dirty_count_severe(void) 1079 { 1080 return(numdirtybuffers >= hidirtybuffers); 1081 } 1082 1083 /* 1084 * brelse: 1085 * 1086 * Release a busy buffer and, if requested, free its resources. The 1087 * buffer will be stashed in the appropriate bufqueue[] allowing it 1088 * to be accessed later as a cache entity or reused for other purposes. 1089 */ 1090 void 1091 brelse(struct buf * bp) 1092 { 1093 #ifdef INVARIANTS 1094 int saved_flags = bp->b_flags; 1095 #endif 1096 1097 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1098 1099 crit_enter(); 1100 1101 if (bp->b_flags & B_LOCKED) 1102 bp->b_flags &= ~B_ERROR; 1103 1104 if ((bp->b_flags & (B_READ | B_ERROR | B_INVAL)) == B_ERROR) { 1105 /* 1106 * Failed write, redirty. Must clear B_ERROR to prevent 1107 * pages from being scrapped. If B_INVAL is set then 1108 * this case is not run and the next case is run to 1109 * destroy the buffer. B_INVAL can occur if the buffer 1110 * is outside the range supported by the underlying device. 1111 */ 1112 bp->b_flags &= ~B_ERROR; 1113 bdirty(bp); 1114 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR | B_FREEBUF)) || 1115 (bp->b_bufsize <= 0)) { 1116 /* 1117 * Either a failed I/O or we were asked to free or not 1118 * cache the buffer. 1119 */ 1120 bp->b_flags |= B_INVAL; 1121 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_deallocate) 1122 (*bioops.io_deallocate)(bp); 1123 if (bp->b_flags & B_DELWRI) { 1124 --numdirtybuffers; 1125 numdirtywakeup(lodirtybuffers); 1126 } 1127 bp->b_flags &= ~(B_DELWRI | B_CACHE | B_FREEBUF); 1128 } 1129 1130 /* 1131 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1132 * is called with B_DELWRI set, the underlying pages may wind up 1133 * getting freed causing a previous write (bdwrite()) to get 'lost' 1134 * because pages associated with a B_DELWRI bp are marked clean. 1135 * 1136 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1137 * if B_DELWRI is set. 1138 * 1139 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1140 * on pages to return pages to the VM page queues. 1141 */ 1142 if (bp->b_flags & B_DELWRI) 1143 bp->b_flags &= ~B_RELBUF; 1144 else if (vm_page_count_severe() && !(bp->b_xflags & BX_BKGRDINPROG)) 1145 bp->b_flags |= B_RELBUF; 1146 1147 /* 1148 * At this point destroying the buffer is governed by the B_INVAL 1149 * or B_RELBUF flags. 1150 */ 1151 1152 /* 1153 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1154 * constituted, not even NFS buffers now. Two flags effect this. If 1155 * B_INVAL, the struct buf is invalidated but the VM object is kept 1156 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1157 * 1158 * If B_ERROR or B_NOCACHE is set, pages in the VM object will be 1159 * invalidated. B_ERROR cannot be set for a failed write unless the 1160 * buffer is also B_INVAL because it hits the re-dirtying code above. 1161 * 1162 * Normally we can do this whether a buffer is B_DELWRI or not. If 1163 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1164 * the commit state and we cannot afford to lose the buffer. If the 1165 * buffer has a background write in progress, we need to keep it 1166 * around to prevent it from being reconstituted and starting a second 1167 * background write. 1168 */ 1169 if ((bp->b_flags & B_VMIO) 1170 && !(bp->b_vp->v_tag == VT_NFS && 1171 !vn_isdisk(bp->b_vp, NULL) && 1172 (bp->b_flags & B_DELWRI)) 1173 ) { 1174 /* 1175 * Rundown for VMIO buffers which are not dirty NFS buffers. 1176 */ 1177 int i, j, resid; 1178 vm_page_t m; 1179 off_t foff; 1180 vm_pindex_t poff; 1181 vm_object_t obj; 1182 struct vnode *vp; 1183 1184 vp = bp->b_vp; 1185 1186 /* 1187 * Get the base offset and length of the buffer. Note that 1188 * in the VMIO case if the buffer block size is not 1189 * page-aligned then b_data pointer may not be page-aligned. 1190 * But our b_xio.xio_pages array *IS* page aligned. 1191 * 1192 * block sizes less then DEV_BSIZE (usually 512) are not 1193 * supported due to the page granularity bits (m->valid, 1194 * m->dirty, etc...). 1195 * 1196 * See man buf(9) for more information 1197 */ 1198 1199 resid = bp->b_bufsize; 1200 foff = bp->b_offset; 1201 1202 for (i = 0; i < bp->b_xio.xio_npages; i++) { 1203 m = bp->b_xio.xio_pages[i]; 1204 vm_page_flag_clear(m, PG_ZERO); 1205 /* 1206 * If we hit a bogus page, fixup *all* of them 1207 * now. Note that we left these pages wired 1208 * when we removed them so they had better exist, 1209 * and they cannot be ripped out from under us so 1210 * no critical section protection is necessary. 1211 */ 1212 if (m == bogus_page) { 1213 VOP_GETVOBJECT(vp, &obj); 1214 poff = OFF_TO_IDX(bp->b_offset); 1215 1216 for (j = i; j < bp->b_xio.xio_npages; j++) { 1217 vm_page_t mtmp; 1218 1219 mtmp = bp->b_xio.xio_pages[j]; 1220 if (mtmp == bogus_page) { 1221 mtmp = vm_page_lookup(obj, poff + j); 1222 if (!mtmp) { 1223 panic("brelse: page missing"); 1224 } 1225 bp->b_xio.xio_pages[j] = mtmp; 1226 } 1227 } 1228 1229 if ((bp->b_flags & B_INVAL) == 0) { 1230 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 1231 bp->b_xio.xio_pages, bp->b_xio.xio_npages); 1232 } 1233 m = bp->b_xio.xio_pages[i]; 1234 } 1235 1236 /* 1237 * Invalidate the backing store if B_NOCACHE is set 1238 * (e.g. used with vinvalbuf()). If this is NFS 1239 * we impose a requirement that the block size be 1240 * a multiple of PAGE_SIZE and create a temporary 1241 * hack to basically invalidate the whole page. The 1242 * problem is that NFS uses really odd buffer sizes 1243 * especially when tracking piecemeal writes and 1244 * it also vinvalbuf()'s a lot, which would result 1245 * in only partial page validation and invalidation 1246 * here. If the file page is mmap()'d, however, 1247 * all the valid bits get set so after we invalidate 1248 * here we would end up with weird m->valid values 1249 * like 0xfc. nfs_getpages() can't handle this so 1250 * we clear all the valid bits for the NFS case 1251 * instead of just some of them. 1252 * 1253 * The real bug is the VM system having to set m->valid 1254 * to VM_PAGE_BITS_ALL for faulted-in pages, which 1255 * itself is an artifact of the whole 512-byte 1256 * granular mess that exists to support odd block 1257 * sizes and UFS meta-data block sizes (e.g. 6144). 1258 * A complete rewrite is required. 1259 */ 1260 if (bp->b_flags & (B_NOCACHE|B_ERROR)) { 1261 int poffset = foff & PAGE_MASK; 1262 int presid; 1263 1264 presid = PAGE_SIZE - poffset; 1265 if (bp->b_vp->v_tag == VT_NFS && 1266 bp->b_vp->v_type == VREG) { 1267 ; /* entire page */ 1268 } else if (presid > resid) { 1269 presid = resid; 1270 } 1271 KASSERT(presid >= 0, ("brelse: extra page")); 1272 vm_page_set_invalid(m, poffset, presid); 1273 } 1274 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1275 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1276 } 1277 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1278 vfs_vmio_release(bp); 1279 } else if (bp->b_flags & B_VMIO) { 1280 /* 1281 * Rundown for VMIO buffers which are dirty NFS buffers. Such 1282 * buffers contain tracking ranges for NFS and cannot normally 1283 * be released. Due to the dirty check above this series of 1284 * conditionals, B_RELBUF probably will never be set in this 1285 * codepath. 1286 */ 1287 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1288 vfs_vmio_release(bp); 1289 } else { 1290 /* 1291 * Rundown for non-VMIO buffers. 1292 */ 1293 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1294 #if 0 1295 if (bp->b_vp) 1296 printf("brelse bp %p %08x/%08lx: Warning, caught and fixed brelvp bug\n", bp, saved_flags, bp->b_flags); 1297 #endif 1298 if (bp->b_bufsize) 1299 allocbuf(bp, 0); 1300 if (bp->b_vp) 1301 brelvp(bp); 1302 } 1303 } 1304 1305 if (bp->b_qindex != BQUEUE_NONE) 1306 panic("brelse: free buffer onto another queue???"); 1307 if (BUF_REFCNTNB(bp) > 1) { 1308 /* Temporary panic to verify exclusive locking */ 1309 /* This panic goes away when we allow shared refs */ 1310 panic("brelse: multiple refs"); 1311 /* do not release to free list */ 1312 BUF_UNLOCK(bp); 1313 crit_exit(); 1314 return; 1315 } 1316 1317 /* 1318 * Figure out the correct queue to place the cleaned up buffer on. 1319 * Buffers placed in the EMPTY or EMPTYKVA had better already be 1320 * disassociated from their vnode. 1321 */ 1322 1323 if (bp->b_bufsize == 0) { 1324 /* 1325 * Buffers with no memory. Due to conditionals near the top 1326 * of brelse() such buffers should probably already be 1327 * marked B_INVAL and disassociated from their vnode. 1328 */ 1329 bp->b_flags |= B_INVAL; 1330 bp->b_xflags &= ~BX_BKGRDWRITE; 1331 KASSERT(bp->b_vp == NULL, ("bp1 %p flags %08x/%08lx vnode %p unexpectededly still associated!", bp, saved_flags, bp->b_flags, bp->b_vp)); 1332 if (bp->b_xflags & BX_BKGRDINPROG) 1333 panic("losing buffer 1"); 1334 if (bp->b_kvasize) { 1335 bp->b_qindex = BQUEUE_EMPTYKVA; 1336 } else { 1337 bp->b_qindex = BQUEUE_EMPTY; 1338 } 1339 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1340 LIST_REMOVE(bp, b_hash); 1341 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1342 bp->b_dev = NODEV; 1343 } else if (bp->b_flags & (B_ERROR | B_INVAL | B_NOCACHE | B_RELBUF)) { 1344 /* 1345 * Buffers with junk contents. Again these buffers had better 1346 * already be disassociated from their vnode. 1347 */ 1348 KASSERT(bp->b_vp == NULL, ("bp2 %p flags %08x/%08lx vnode %p unexpectededly still associated!", bp, saved_flags, bp->b_flags, bp->b_vp)); 1349 bp->b_flags |= B_INVAL; 1350 bp->b_xflags &= ~BX_BKGRDWRITE; 1351 if (bp->b_xflags & BX_BKGRDINPROG) 1352 panic("losing buffer 2"); 1353 bp->b_qindex = BQUEUE_CLEAN; 1354 TAILQ_INSERT_HEAD(&bufqueues[BQUEUE_CLEAN], bp, b_freelist); 1355 LIST_REMOVE(bp, b_hash); 1356 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1357 bp->b_dev = NODEV; 1358 } else if (bp->b_flags & B_LOCKED) { 1359 /* 1360 * Buffers that are locked. 1361 */ 1362 bp->b_qindex = BQUEUE_LOCKED; 1363 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_LOCKED], bp, b_freelist); 1364 } else { 1365 /* 1366 * Remaining buffers. These buffers are still associated with 1367 * their vnode. 1368 */ 1369 switch(bp->b_flags & (B_DELWRI|B_AGE)) { 1370 case B_DELWRI | B_AGE: 1371 bp->b_qindex = BQUEUE_DIRTY; 1372 TAILQ_INSERT_HEAD(&bufqueues[BQUEUE_DIRTY], bp, b_freelist); 1373 break; 1374 case B_DELWRI: 1375 bp->b_qindex = BQUEUE_DIRTY; 1376 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_DIRTY], bp, b_freelist); 1377 break; 1378 case B_AGE: 1379 bp->b_qindex = BQUEUE_CLEAN; 1380 TAILQ_INSERT_HEAD(&bufqueues[BQUEUE_CLEAN], bp, b_freelist); 1381 break; 1382 default: 1383 bp->b_qindex = BQUEUE_CLEAN; 1384 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_CLEAN], bp, b_freelist); 1385 break; 1386 } 1387 } 1388 1389 /* 1390 * If B_INVAL, clear B_DELWRI. We've already placed the buffer 1391 * on the correct queue. 1392 */ 1393 if ((bp->b_flags & (B_INVAL|B_DELWRI)) == (B_INVAL|B_DELWRI)) 1394 bundirty(bp); 1395 1396 /* 1397 * Fixup numfreebuffers count. The bp is on an appropriate queue 1398 * unless locked. We then bump numfreebuffers if it is not B_DELWRI. 1399 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1400 * if B_INVAL is set ). 1401 */ 1402 if ((bp->b_flags & B_LOCKED) == 0 && !(bp->b_flags & B_DELWRI)) 1403 bufcountwakeup(); 1404 1405 /* 1406 * Something we can maybe free or reuse 1407 */ 1408 if (bp->b_bufsize || bp->b_kvasize) 1409 bufspacewakeup(); 1410 1411 /* unlock */ 1412 BUF_UNLOCK(bp); 1413 bp->b_flags &= ~(B_ORDERED | B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | 1414 B_DIRECT | B_NOWDRAIN); 1415 crit_exit(); 1416 } 1417 1418 /* 1419 * bqrelse: 1420 * 1421 * Release a buffer back to the appropriate queue but do not try to free 1422 * it. The buffer is expected to be used again soon. 1423 * 1424 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1425 * biodone() to requeue an async I/O on completion. It is also used when 1426 * known good buffers need to be requeued but we think we may need the data 1427 * again soon. 1428 * 1429 * XXX we should be able to leave the B_RELBUF hint set on completion. 1430 */ 1431 void 1432 bqrelse(struct buf * bp) 1433 { 1434 crit_enter(); 1435 1436 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1437 1438 if (bp->b_qindex != BQUEUE_NONE) 1439 panic("bqrelse: free buffer onto another queue???"); 1440 if (BUF_REFCNTNB(bp) > 1) { 1441 /* do not release to free list */ 1442 panic("bqrelse: multiple refs"); 1443 BUF_UNLOCK(bp); 1444 crit_exit(); 1445 return; 1446 } 1447 if (bp->b_flags & B_LOCKED) { 1448 bp->b_flags &= ~B_ERROR; 1449 bp->b_qindex = BQUEUE_LOCKED; 1450 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_LOCKED], bp, b_freelist); 1451 /* buffers with stale but valid contents */ 1452 } else if (bp->b_flags & B_DELWRI) { 1453 bp->b_qindex = BQUEUE_DIRTY; 1454 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_DIRTY], bp, b_freelist); 1455 } else if (vm_page_count_severe()) { 1456 /* 1457 * We are too low on memory, we have to try to free the 1458 * buffer (most importantly: the wired pages making up its 1459 * backing store) *now*. 1460 */ 1461 crit_exit(); 1462 brelse(bp); 1463 return; 1464 } else { 1465 bp->b_qindex = BQUEUE_CLEAN; 1466 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_CLEAN], bp, b_freelist); 1467 } 1468 1469 if ((bp->b_flags & B_LOCKED) == 0 && 1470 ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI))) { 1471 bufcountwakeup(); 1472 } 1473 1474 /* 1475 * Something we can maybe free or reuse. 1476 */ 1477 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1478 bufspacewakeup(); 1479 1480 /* 1481 * Final cleanup and unlock. Clear bits that are only used while a 1482 * buffer is actively locked. 1483 */ 1484 bp->b_flags &= ~(B_ORDERED | B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1485 BUF_UNLOCK(bp); 1486 crit_exit(); 1487 } 1488 1489 /* 1490 * vfs_vmio_release: 1491 * 1492 * Return backing pages held by the buffer 'bp' back to the VM system 1493 * if possible. The pages are freed if they are no longer valid or 1494 * attempt to free if it was used for direct I/O otherwise they are 1495 * sent to the page cache. 1496 * 1497 * Pages that were marked busy are left alone and skipped. 1498 * 1499 * The KVA mapping (b_data) for the underlying pages is removed by 1500 * this function. 1501 */ 1502 static void 1503 vfs_vmio_release(struct buf *bp) 1504 { 1505 int i; 1506 vm_page_t m; 1507 1508 crit_enter(); 1509 for (i = 0; i < bp->b_xio.xio_npages; i++) { 1510 m = bp->b_xio.xio_pages[i]; 1511 bp->b_xio.xio_pages[i] = NULL; 1512 /* 1513 * In order to keep page LRU ordering consistent, put 1514 * everything on the inactive queue. 1515 */ 1516 vm_page_unwire(m, 0); 1517 /* 1518 * We don't mess with busy pages, it is 1519 * the responsibility of the process that 1520 * busied the pages to deal with them. 1521 */ 1522 if ((m->flags & PG_BUSY) || (m->busy != 0)) 1523 continue; 1524 1525 if (m->wire_count == 0) { 1526 vm_page_flag_clear(m, PG_ZERO); 1527 /* 1528 * Might as well free the page if we can and it has 1529 * no valid data. We also free the page if the 1530 * buffer was used for direct I/O. 1531 */ 1532 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && 1533 m->hold_count == 0) { 1534 vm_page_busy(m); 1535 vm_page_protect(m, VM_PROT_NONE); 1536 vm_page_free(m); 1537 } else if (bp->b_flags & B_DIRECT) { 1538 vm_page_try_to_free(m); 1539 } else if (vm_page_count_severe()) { 1540 vm_page_try_to_cache(m); 1541 } 1542 } 1543 } 1544 crit_exit(); 1545 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_xio.xio_npages); 1546 if (bp->b_bufsize) { 1547 bufspacewakeup(); 1548 bp->b_bufsize = 0; 1549 } 1550 bp->b_xio.xio_npages = 0; 1551 bp->b_flags &= ~B_VMIO; 1552 if (bp->b_vp) 1553 brelvp(bp); 1554 } 1555 1556 /* 1557 * gbincore: 1558 * 1559 * Check to see if a block is currently memory resident. 1560 */ 1561 struct buf * 1562 gbincore(struct vnode * vp, daddr_t blkno) 1563 { 1564 struct buf *bp; 1565 struct bufhashhdr *bh; 1566 1567 bh = bufhash(vp, blkno); 1568 LIST_FOREACH(bp, bh, b_hash) { 1569 if (bp->b_vp == vp && bp->b_lblkno == blkno) 1570 break; 1571 } 1572 return (bp); 1573 } 1574 1575 /* 1576 * vfs_bio_awrite: 1577 * 1578 * Implement clustered async writes for clearing out B_DELWRI buffers. 1579 * This is much better then the old way of writing only one buffer at 1580 * a time. Note that we may not be presented with the buffers in the 1581 * correct order, so we search for the cluster in both directions. 1582 */ 1583 int 1584 vfs_bio_awrite(struct buf * bp) 1585 { 1586 int i; 1587 int j; 1588 daddr_t lblkno = bp->b_lblkno; 1589 struct vnode *vp = bp->b_vp; 1590 int ncl; 1591 struct buf *bpa; 1592 int nwritten; 1593 int size; 1594 int maxcl; 1595 1596 crit_enter(); 1597 /* 1598 * right now we support clustered writing only to regular files. If 1599 * we find a clusterable block we could be in the middle of a cluster 1600 * rather then at the beginning. 1601 */ 1602 if ((vp->v_type == VREG) && 1603 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1604 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1605 1606 size = vp->v_mount->mnt_stat.f_iosize; 1607 maxcl = MAXPHYS / size; 1608 1609 for (i = 1; i < maxcl; i++) { 1610 if ((bpa = gbincore(vp, lblkno + i)) && 1611 BUF_REFCNT(bpa) == 0 && 1612 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == 1613 (B_DELWRI | B_CLUSTEROK)) && 1614 (bpa->b_bufsize == size)) { 1615 if ((bpa->b_blkno == bpa->b_lblkno) || 1616 (bpa->b_blkno != 1617 bp->b_blkno + ((i * size) >> DEV_BSHIFT))) 1618 break; 1619 } else { 1620 break; 1621 } 1622 } 1623 for (j = 1; i + j <= maxcl && j <= lblkno; j++) { 1624 if ((bpa = gbincore(vp, lblkno - j)) && 1625 BUF_REFCNT(bpa) == 0 && 1626 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == 1627 (B_DELWRI | B_CLUSTEROK)) && 1628 (bpa->b_bufsize == size)) { 1629 if ((bpa->b_blkno == bpa->b_lblkno) || 1630 (bpa->b_blkno != 1631 bp->b_blkno - ((j * size) >> DEV_BSHIFT))) 1632 break; 1633 } else { 1634 break; 1635 } 1636 } 1637 --j; 1638 ncl = i + j; 1639 /* 1640 * this is a possible cluster write 1641 */ 1642 if (ncl != 1) { 1643 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl); 1644 crit_exit(); 1645 return nwritten; 1646 } 1647 } 1648 1649 BUF_LOCK(bp, LK_EXCLUSIVE); 1650 bremfree(bp); 1651 bp->b_flags |= B_ASYNC; 1652 1653 crit_exit(); 1654 /* 1655 * default (old) behavior, writing out only one block 1656 * 1657 * XXX returns b_bufsize instead of b_bcount for nwritten? 1658 */ 1659 nwritten = bp->b_bufsize; 1660 (void) VOP_BWRITE(bp->b_vp, bp); 1661 1662 return nwritten; 1663 } 1664 1665 /* 1666 * getnewbuf: 1667 * 1668 * Find and initialize a new buffer header, freeing up existing buffers 1669 * in the bufqueues as necessary. The new buffer is returned locked. 1670 * 1671 * Important: B_INVAL is not set. If the caller wishes to throw the 1672 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1673 * 1674 * We block if: 1675 * We have insufficient buffer headers 1676 * We have insufficient buffer space 1677 * buffer_map is too fragmented ( space reservation fails ) 1678 * If we have to flush dirty buffers ( but we try to avoid this ) 1679 * 1680 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1681 * Instead we ask the buf daemon to do it for us. We attempt to 1682 * avoid piecemeal wakeups of the pageout daemon. 1683 */ 1684 1685 static struct buf * 1686 getnewbuf(int slpflag, int slptimeo, int size, int maxsize) 1687 { 1688 struct buf *bp; 1689 struct buf *nbp; 1690 int defrag = 0; 1691 int nqindex; 1692 static int flushingbufs; 1693 1694 /* 1695 * We can't afford to block since we might be holding a vnode lock, 1696 * which may prevent system daemons from running. We deal with 1697 * low-memory situations by proactively returning memory and running 1698 * async I/O rather then sync I/O. 1699 */ 1700 1701 ++getnewbufcalls; 1702 --getnewbufrestarts; 1703 restart: 1704 ++getnewbufrestarts; 1705 1706 /* 1707 * Setup for scan. If we do not have enough free buffers, 1708 * we setup a degenerate case that immediately fails. Note 1709 * that if we are specially marked process, we are allowed to 1710 * dip into our reserves. 1711 * 1712 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 1713 * 1714 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 1715 * However, there are a number of cases (defragging, reusing, ...) 1716 * where we cannot backup. 1717 */ 1718 nqindex = BQUEUE_EMPTYKVA; 1719 nbp = TAILQ_FIRST(&bufqueues[BQUEUE_EMPTYKVA]); 1720 1721 if (nbp == NULL) { 1722 /* 1723 * If no EMPTYKVA buffers and we are either 1724 * defragging or reusing, locate a CLEAN buffer 1725 * to free or reuse. If bufspace useage is low 1726 * skip this step so we can allocate a new buffer. 1727 */ 1728 if (defrag || bufspace >= lobufspace) { 1729 nqindex = BQUEUE_CLEAN; 1730 nbp = TAILQ_FIRST(&bufqueues[BQUEUE_CLEAN]); 1731 } 1732 1733 /* 1734 * If we could not find or were not allowed to reuse a 1735 * CLEAN buffer, check to see if it is ok to use an EMPTY 1736 * buffer. We can only use an EMPTY buffer if allocating 1737 * its KVA would not otherwise run us out of buffer space. 1738 */ 1739 if (nbp == NULL && defrag == 0 && 1740 bufspace + maxsize < hibufspace) { 1741 nqindex = BQUEUE_EMPTY; 1742 nbp = TAILQ_FIRST(&bufqueues[BQUEUE_EMPTY]); 1743 } 1744 } 1745 1746 /* 1747 * Run scan, possibly freeing data and/or kva mappings on the fly 1748 * depending. 1749 */ 1750 1751 while ((bp = nbp) != NULL) { 1752 int qindex = nqindex; 1753 1754 /* 1755 * Calculate next bp ( we can only use it if we do not block 1756 * or do other fancy things ). 1757 */ 1758 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 1759 switch(qindex) { 1760 case BQUEUE_EMPTY: 1761 nqindex = BQUEUE_EMPTYKVA; 1762 if ((nbp = TAILQ_FIRST(&bufqueues[BQUEUE_EMPTYKVA]))) 1763 break; 1764 /* fall through */ 1765 case BQUEUE_EMPTYKVA: 1766 nqindex = BQUEUE_CLEAN; 1767 if ((nbp = TAILQ_FIRST(&bufqueues[BQUEUE_CLEAN]))) 1768 break; 1769 /* fall through */ 1770 case BQUEUE_CLEAN: 1771 /* 1772 * nbp is NULL. 1773 */ 1774 break; 1775 } 1776 } 1777 1778 /* 1779 * Sanity Checks 1780 */ 1781 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp)); 1782 1783 /* 1784 * Note: we no longer distinguish between VMIO and non-VMIO 1785 * buffers. 1786 */ 1787 1788 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); 1789 1790 /* 1791 * If we are defragging then we need a buffer with 1792 * b_kvasize != 0. XXX this situation should no longer 1793 * occur, if defrag is non-zero the buffer's b_kvasize 1794 * should also be non-zero at this point. XXX 1795 */ 1796 if (defrag && bp->b_kvasize == 0) { 1797 printf("Warning: defrag empty buffer %p\n", bp); 1798 continue; 1799 } 1800 1801 /* 1802 * Start freeing the bp. This is somewhat involved. nbp 1803 * remains valid only for BQUEUE_EMPTY[KVA] bp's. Buffers 1804 * on the clean list must be disassociated from their 1805 * current vnode. Buffers on the empty[kva] lists have 1806 * already been disassociated. 1807 */ 1808 1809 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) 1810 panic("getnewbuf: locked buf"); 1811 bremfree(bp); 1812 1813 if (qindex == BQUEUE_CLEAN) { 1814 if (bp->b_flags & B_VMIO) { 1815 bp->b_flags &= ~B_ASYNC; 1816 vfs_vmio_release(bp); 1817 } 1818 if (bp->b_vp) 1819 brelvp(bp); 1820 } 1821 1822 /* 1823 * NOTE: nbp is now entirely invalid. We can only restart 1824 * the scan from this point on. 1825 * 1826 * Get the rest of the buffer freed up. b_kva* is still 1827 * valid after this operation. 1828 */ 1829 1830 KASSERT(bp->b_vp == NULL, ("bp3 %p flags %08lx vnode %p qindex %d unexpectededly still associated!", bp, bp->b_flags, bp->b_vp, qindex)); 1831 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_deallocate) 1832 (*bioops.io_deallocate)(bp); 1833 if (bp->b_xflags & BX_BKGRDINPROG) 1834 panic("losing buffer 3"); 1835 LIST_REMOVE(bp, b_hash); 1836 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1837 1838 /* 1839 * critical section protection is not required when 1840 * scrapping a buffer's contents because it is already 1841 * wired. 1842 */ 1843 if (bp->b_bufsize) 1844 allocbuf(bp, 0); 1845 1846 bp->b_flags = 0; 1847 bp->b_xflags = 0; 1848 bp->b_dev = NODEV; 1849 bp->b_vp = NULL; 1850 bp->b_blkno = bp->b_lblkno = 0; 1851 bp->b_offset = NOOFFSET; 1852 bp->b_iodone = NULL; 1853 bp->b_error = 0; 1854 bp->b_resid = 0; 1855 bp->b_bcount = 0; 1856 bp->b_xio.xio_npages = 0; 1857 bp->b_dirtyoff = bp->b_dirtyend = 0; 1858 1859 LIST_INIT(&bp->b_dep); 1860 1861 /* 1862 * If we are defragging then free the buffer. 1863 */ 1864 if (defrag) { 1865 bp->b_flags |= B_INVAL; 1866 bfreekva(bp); 1867 brelse(bp); 1868 defrag = 0; 1869 goto restart; 1870 } 1871 1872 /* 1873 * If we are overcomitted then recover the buffer and its 1874 * KVM space. This occurs in rare situations when multiple 1875 * processes are blocked in getnewbuf() or allocbuf(). 1876 */ 1877 if (bufspace >= hibufspace) 1878 flushingbufs = 1; 1879 if (flushingbufs && bp->b_kvasize != 0) { 1880 bp->b_flags |= B_INVAL; 1881 bfreekva(bp); 1882 brelse(bp); 1883 goto restart; 1884 } 1885 if (bufspace < lobufspace) 1886 flushingbufs = 0; 1887 break; 1888 } 1889 1890 /* 1891 * If we exhausted our list, sleep as appropriate. We may have to 1892 * wakeup various daemons and write out some dirty buffers. 1893 * 1894 * Generally we are sleeping due to insufficient buffer space. 1895 */ 1896 1897 if (bp == NULL) { 1898 int flags; 1899 char *waitmsg; 1900 1901 if (defrag) { 1902 flags = VFS_BIO_NEED_BUFSPACE; 1903 waitmsg = "nbufkv"; 1904 } else if (bufspace >= hibufspace) { 1905 waitmsg = "nbufbs"; 1906 flags = VFS_BIO_NEED_BUFSPACE; 1907 } else { 1908 waitmsg = "newbuf"; 1909 flags = VFS_BIO_NEED_ANY; 1910 } 1911 1912 bd_speedup(); /* heeeelp */ 1913 1914 needsbuffer |= flags; 1915 while (needsbuffer & flags) { 1916 if (tsleep(&needsbuffer, slpflag, waitmsg, slptimeo)) 1917 return (NULL); 1918 } 1919 } else { 1920 /* 1921 * We finally have a valid bp. We aren't quite out of the 1922 * woods, we still have to reserve kva space. In order 1923 * to keep fragmentation sane we only allocate kva in 1924 * BKVASIZE chunks. 1925 */ 1926 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 1927 1928 if (maxsize != bp->b_kvasize) { 1929 vm_offset_t addr = 0; 1930 int count; 1931 1932 bfreekva(bp); 1933 1934 count = vm_map_entry_reserve(MAP_RESERVE_COUNT); 1935 vm_map_lock(buffer_map); 1936 1937 if (vm_map_findspace(buffer_map, 1938 vm_map_min(buffer_map), maxsize, 1939 maxsize, &addr)) { 1940 /* 1941 * Uh oh. Buffer map is too fragmented. We 1942 * must defragment the map. 1943 */ 1944 vm_map_unlock(buffer_map); 1945 vm_map_entry_release(count); 1946 ++bufdefragcnt; 1947 defrag = 1; 1948 bp->b_flags |= B_INVAL; 1949 brelse(bp); 1950 goto restart; 1951 } 1952 if (addr) { 1953 vm_map_insert(buffer_map, &count, 1954 NULL, 0, 1955 addr, addr + maxsize, 1956 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT); 1957 1958 bp->b_kvabase = (caddr_t) addr; 1959 bp->b_kvasize = maxsize; 1960 bufspace += bp->b_kvasize; 1961 ++bufreusecnt; 1962 } 1963 vm_map_unlock(buffer_map); 1964 vm_map_entry_release(count); 1965 } 1966 bp->b_data = bp->b_kvabase; 1967 } 1968 return(bp); 1969 } 1970 1971 /* 1972 * buf_daemon: 1973 * 1974 * Buffer flushing daemon. Buffers are normally flushed by the 1975 * update daemon but if it cannot keep up this process starts to 1976 * take the load in an attempt to prevent getnewbuf() from blocking. 1977 */ 1978 1979 static struct thread *bufdaemonthread; 1980 1981 static struct kproc_desc buf_kp = { 1982 "bufdaemon", 1983 buf_daemon, 1984 &bufdaemonthread 1985 }; 1986 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp) 1987 1988 static void 1989 buf_daemon() 1990 { 1991 /* 1992 * This process needs to be suspended prior to shutdown sync. 1993 */ 1994 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc, 1995 bufdaemonthread, SHUTDOWN_PRI_LAST); 1996 1997 /* 1998 * This process is allowed to take the buffer cache to the limit 1999 */ 2000 crit_enter(); 2001 2002 for (;;) { 2003 kproc_suspend_loop(); 2004 2005 /* 2006 * Do the flush. Limit the amount of in-transit I/O we 2007 * allow to build up, otherwise we would completely saturate 2008 * the I/O system. Wakeup any waiting processes before we 2009 * normally would so they can run in parallel with our drain. 2010 */ 2011 while (numdirtybuffers > lodirtybuffers) { 2012 if (flushbufqueues() == 0) 2013 break; 2014 waitrunningbufspace(); 2015 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2016 } 2017 2018 /* 2019 * Only clear bd_request if we have reached our low water 2020 * mark. The buf_daemon normally waits 5 seconds and 2021 * then incrementally flushes any dirty buffers that have 2022 * built up, within reason. 2023 * 2024 * If we were unable to hit our low water mark and couldn't 2025 * find any flushable buffers, we sleep half a second. 2026 * Otherwise we loop immediately. 2027 */ 2028 if (numdirtybuffers <= lodirtybuffers) { 2029 /* 2030 * We reached our low water mark, reset the 2031 * request and sleep until we are needed again. 2032 * The sleep is just so the suspend code works. 2033 */ 2034 bd_request = 0; 2035 tsleep(&bd_request, 0, "psleep", hz); 2036 } else { 2037 /* 2038 * We couldn't find any flushable dirty buffers but 2039 * still have too many dirty buffers, we 2040 * have to sleep and try again. (rare) 2041 */ 2042 tsleep(&bd_request, 0, "qsleep", hz / 2); 2043 } 2044 } 2045 } 2046 2047 /* 2048 * flushbufqueues: 2049 * 2050 * Try to flush a buffer in the dirty queue. We must be careful to 2051 * free up B_INVAL buffers instead of write them, which NFS is 2052 * particularly sensitive to. 2053 */ 2054 2055 static int 2056 flushbufqueues(void) 2057 { 2058 struct buf *bp; 2059 int r = 0; 2060 2061 bp = TAILQ_FIRST(&bufqueues[BQUEUE_DIRTY]); 2062 2063 while (bp) { 2064 KASSERT((bp->b_flags & B_DELWRI), ("unexpected clean buffer %p", bp)); 2065 if ((bp->b_flags & B_DELWRI) != 0 && 2066 (bp->b_xflags & BX_BKGRDINPROG) == 0) { 2067 if (bp->b_flags & B_INVAL) { 2068 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) 2069 panic("flushbufqueues: locked buf"); 2070 bremfree(bp); 2071 brelse(bp); 2072 ++r; 2073 break; 2074 } 2075 if (LIST_FIRST(&bp->b_dep) != NULL && 2076 bioops.io_countdeps && 2077 (bp->b_flags & B_DEFERRED) == 0 && 2078 (*bioops.io_countdeps)(bp, 0)) { 2079 TAILQ_REMOVE(&bufqueues[BQUEUE_DIRTY], 2080 bp, b_freelist); 2081 TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_DIRTY], 2082 bp, b_freelist); 2083 bp->b_flags |= B_DEFERRED; 2084 bp = TAILQ_FIRST(&bufqueues[BQUEUE_DIRTY]); 2085 continue; 2086 } 2087 vfs_bio_awrite(bp); 2088 ++r; 2089 break; 2090 } 2091 bp = TAILQ_NEXT(bp, b_freelist); 2092 } 2093 return (r); 2094 } 2095 2096 /* 2097 * incore: 2098 * 2099 * Check to see if a block is currently resident in memory. 2100 */ 2101 struct buf * 2102 incore(struct vnode * vp, daddr_t blkno) 2103 { 2104 struct buf *bp; 2105 2106 crit_enter(); 2107 bp = gbincore(vp, blkno); 2108 crit_exit(); 2109 return (bp); 2110 } 2111 2112 /* 2113 * inmem: 2114 * 2115 * Returns true if no I/O is needed to access the associated VM object. 2116 * This is like incore except it also hunts around in the VM system for 2117 * the data. 2118 * 2119 * Note that we ignore vm_page_free() races from interrupts against our 2120 * lookup, since if the caller is not protected our return value will not 2121 * be any more valid then otherwise once we exit the critical section. 2122 */ 2123 int 2124 inmem(struct vnode * vp, daddr_t blkno) 2125 { 2126 vm_object_t obj; 2127 vm_offset_t toff, tinc, size; 2128 vm_page_t m; 2129 vm_ooffset_t off; 2130 2131 if (incore(vp, blkno)) 2132 return 1; 2133 if (vp->v_mount == NULL) 2134 return 0; 2135 if (VOP_GETVOBJECT(vp, &obj) != 0 || (vp->v_flag & VOBJBUF) == 0) 2136 return 0; 2137 2138 size = PAGE_SIZE; 2139 if (size > vp->v_mount->mnt_stat.f_iosize) 2140 size = vp->v_mount->mnt_stat.f_iosize; 2141 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2142 2143 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2144 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2145 if (!m) 2146 return 0; 2147 tinc = size; 2148 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2149 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2150 if (vm_page_is_valid(m, 2151 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2152 return 0; 2153 } 2154 return 1; 2155 } 2156 2157 /* 2158 * vfs_setdirty: 2159 * 2160 * Sets the dirty range for a buffer based on the status of the dirty 2161 * bits in the pages comprising the buffer. 2162 * 2163 * The range is limited to the size of the buffer. 2164 * 2165 * This routine is primarily used by NFS, but is generalized for the 2166 * B_VMIO case. 2167 */ 2168 static void 2169 vfs_setdirty(struct buf *bp) 2170 { 2171 int i; 2172 vm_object_t object; 2173 2174 /* 2175 * Degenerate case - empty buffer 2176 */ 2177 2178 if (bp->b_bufsize == 0) 2179 return; 2180 2181 /* 2182 * We qualify the scan for modified pages on whether the 2183 * object has been flushed yet. The OBJ_WRITEABLE flag 2184 * is not cleared simply by protecting pages off. 2185 */ 2186 2187 if ((bp->b_flags & B_VMIO) == 0) 2188 return; 2189 2190 object = bp->b_xio.xio_pages[0]->object; 2191 2192 if ((object->flags & OBJ_WRITEABLE) && !(object->flags & OBJ_MIGHTBEDIRTY)) 2193 printf("Warning: object %p writeable but not mightbedirty\n", object); 2194 if (!(object->flags & OBJ_WRITEABLE) && (object->flags & OBJ_MIGHTBEDIRTY)) 2195 printf("Warning: object %p mightbedirty but not writeable\n", object); 2196 2197 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) { 2198 vm_offset_t boffset; 2199 vm_offset_t eoffset; 2200 2201 /* 2202 * test the pages to see if they have been modified directly 2203 * by users through the VM system. 2204 */ 2205 for (i = 0; i < bp->b_xio.xio_npages; i++) { 2206 vm_page_flag_clear(bp->b_xio.xio_pages[i], PG_ZERO); 2207 vm_page_test_dirty(bp->b_xio.xio_pages[i]); 2208 } 2209 2210 /* 2211 * Calculate the encompassing dirty range, boffset and eoffset, 2212 * (eoffset - boffset) bytes. 2213 */ 2214 2215 for (i = 0; i < bp->b_xio.xio_npages; i++) { 2216 if (bp->b_xio.xio_pages[i]->dirty) 2217 break; 2218 } 2219 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2220 2221 for (i = bp->b_xio.xio_npages - 1; i >= 0; --i) { 2222 if (bp->b_xio.xio_pages[i]->dirty) { 2223 break; 2224 } 2225 } 2226 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2227 2228 /* 2229 * Fit it to the buffer. 2230 */ 2231 2232 if (eoffset > bp->b_bcount) 2233 eoffset = bp->b_bcount; 2234 2235 /* 2236 * If we have a good dirty range, merge with the existing 2237 * dirty range. 2238 */ 2239 2240 if (boffset < eoffset) { 2241 if (bp->b_dirtyoff > boffset) 2242 bp->b_dirtyoff = boffset; 2243 if (bp->b_dirtyend < eoffset) 2244 bp->b_dirtyend = eoffset; 2245 } 2246 } 2247 } 2248 2249 /* 2250 * getblk: 2251 * 2252 * Get a block given a specified block and offset into a file/device. 2253 * The buffers B_DONE bit will be cleared on return, making it almost 2254 * ready for an I/O initiation. B_INVAL may or may not be set on 2255 * return. The caller should clear B_INVAL prior to initiating a 2256 * READ. 2257 * 2258 * IT IS IMPORTANT TO UNDERSTAND THAT IF YOU CALL GETBLK() AND B_CACHE 2259 * IS NOT SET, YOU MUST INITIALIZE THE RETURNED BUFFER, ISSUE A READ, 2260 * OR SET B_INVAL BEFORE RETIRING IT. If you retire a getblk'd buffer 2261 * without doing any of those things the system will likely believe 2262 * the buffer to be valid (especially if it is not B_VMIO), and the 2263 * next getblk() will return the buffer with B_CACHE set. 2264 * 2265 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2266 * an existing buffer. 2267 * 2268 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2269 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2270 * and then cleared based on the backing VM. If the previous buffer is 2271 * non-0-sized but invalid, B_CACHE will be cleared. 2272 * 2273 * If getblk() must create a new buffer, the new buffer is returned with 2274 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2275 * case it is returned with B_INVAL clear and B_CACHE set based on the 2276 * backing VM. 2277 * 2278 * getblk() also forces a VOP_BWRITE() for any B_DELWRI buffer whos 2279 * B_CACHE bit is clear. 2280 * 2281 * What this means, basically, is that the caller should use B_CACHE to 2282 * determine whether the buffer is fully valid or not and should clear 2283 * B_INVAL prior to issuing a read. If the caller intends to validate 2284 * the buffer by loading its data area with something, the caller needs 2285 * to clear B_INVAL. If the caller does this without issuing an I/O, 2286 * the caller should set B_CACHE ( as an optimization ), else the caller 2287 * should issue the I/O and biodone() will set B_CACHE if the I/O was 2288 * a write attempt or if it was a successfull read. If the caller 2289 * intends to issue a READ, the caller must clear B_INVAL and B_ERROR 2290 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 2291 */ 2292 struct buf * 2293 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo) 2294 { 2295 struct buf *bp; 2296 struct bufhashhdr *bh; 2297 2298 if (size > MAXBSIZE) 2299 panic("getblk: size(%d) > MAXBSIZE(%d)", size, MAXBSIZE); 2300 2301 crit_enter(); 2302 loop: 2303 /* 2304 * Block if we are low on buffers. Certain processes are allowed 2305 * to completely exhaust the buffer cache. 2306 * 2307 * If this check ever becomes a bottleneck it may be better to 2308 * move it into the else, when gbincore() fails. At the moment 2309 * it isn't a problem. 2310 * 2311 * XXX remove, we cannot afford to block anywhere if holding a vnode 2312 * lock in low-memory situation, so take it to the max. 2313 */ 2314 if (numfreebuffers == 0) { 2315 if (!curproc) 2316 return NULL; 2317 needsbuffer |= VFS_BIO_NEED_ANY; 2318 tsleep(&needsbuffer, slpflag, "newbuf", slptimeo); 2319 } 2320 2321 if ((bp = gbincore(vp, blkno))) { 2322 /* 2323 * Buffer is in-core. If the buffer is not busy, it must 2324 * be on a queue. 2325 */ 2326 2327 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) { 2328 if (BUF_TIMELOCK(bp, LK_EXCLUSIVE | LK_SLEEPFAIL, 2329 "getblk", slpflag, slptimeo) == ENOLCK) 2330 goto loop; 2331 crit_exit(); 2332 return (struct buf *) NULL; 2333 } 2334 2335 /* 2336 * The buffer is locked. B_CACHE is cleared if the buffer is 2337 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 2338 * and for a VMIO buffer B_CACHE is adjusted according to the 2339 * backing VM cache. 2340 */ 2341 if (bp->b_flags & B_INVAL) 2342 bp->b_flags &= ~B_CACHE; 2343 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 2344 bp->b_flags |= B_CACHE; 2345 bremfree(bp); 2346 2347 /* 2348 * check for size inconsistancies for non-VMIO case. 2349 */ 2350 2351 if (bp->b_bcount != size) { 2352 if ((bp->b_flags & B_VMIO) == 0 || 2353 (size > bp->b_kvasize)) { 2354 if (bp->b_flags & B_DELWRI) { 2355 bp->b_flags |= B_NOCACHE; 2356 VOP_BWRITE(bp->b_vp, bp); 2357 } else { 2358 if ((bp->b_flags & B_VMIO) && 2359 (LIST_FIRST(&bp->b_dep) == NULL)) { 2360 bp->b_flags |= B_RELBUF; 2361 brelse(bp); 2362 } else { 2363 bp->b_flags |= B_NOCACHE; 2364 VOP_BWRITE(bp->b_vp, bp); 2365 } 2366 } 2367 goto loop; 2368 } 2369 } 2370 2371 /* 2372 * If the size is inconsistant in the VMIO case, we can resize 2373 * the buffer. This might lead to B_CACHE getting set or 2374 * cleared. If the size has not changed, B_CACHE remains 2375 * unchanged from its previous state. 2376 */ 2377 2378 if (bp->b_bcount != size) 2379 allocbuf(bp, size); 2380 2381 KASSERT(bp->b_offset != NOOFFSET, 2382 ("getblk: no buffer offset")); 2383 2384 /* 2385 * A buffer with B_DELWRI set and B_CACHE clear must 2386 * be committed before we can return the buffer in 2387 * order to prevent the caller from issuing a read 2388 * ( due to B_CACHE not being set ) and overwriting 2389 * it. 2390 * 2391 * Most callers, including NFS and FFS, need this to 2392 * operate properly either because they assume they 2393 * can issue a read if B_CACHE is not set, or because 2394 * ( for example ) an uncached B_DELWRI might loop due 2395 * to softupdates re-dirtying the buffer. In the latter 2396 * case, B_CACHE is set after the first write completes, 2397 * preventing further loops. 2398 * 2399 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 2400 * above while extending the buffer, we cannot allow the 2401 * buffer to remain with B_CACHE set after the write 2402 * completes or it will represent a corrupt state. To 2403 * deal with this we set B_NOCACHE to scrap the buffer 2404 * after the write. 2405 * 2406 * We might be able to do something fancy, like setting 2407 * B_CACHE in bwrite() except if B_DELWRI is already set, 2408 * so the below call doesn't set B_CACHE, but that gets real 2409 * confusing. This is much easier. 2410 */ 2411 2412 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 2413 bp->b_flags |= B_NOCACHE; 2414 VOP_BWRITE(bp->b_vp, bp); 2415 goto loop; 2416 } 2417 2418 crit_exit(); 2419 bp->b_flags &= ~B_DONE; 2420 } else { 2421 /* 2422 * Buffer is not in-core, create new buffer. The buffer 2423 * returned by getnewbuf() is locked. Note that the returned 2424 * buffer is also considered valid (not marked B_INVAL). 2425 * 2426 * Calculating the offset for the I/O requires figuring out 2427 * the block size. We use DEV_BSIZE for VBLK or VCHR and 2428 * the mount's f_iosize otherwise. If the vnode does not 2429 * have an associated mount we assume that the passed size is 2430 * the block size. 2431 * 2432 * Note that vn_isdisk() cannot be used here since it may 2433 * return a failure for numerous reasons. Note that the 2434 * buffer size may be larger then the block size (the caller 2435 * will use block numbers with the proper multiple). Beware 2436 * of using any v_* fields which are part of unions. In 2437 * particular, in DragonFly the mount point overloading 2438 * mechanism is such that the underlying directory (with a 2439 * non-NULL v_mountedhere) is not a special case. 2440 */ 2441 int bsize, maxsize, vmio; 2442 off_t offset; 2443 2444 if (vp->v_type == VBLK || vp->v_type == VCHR) 2445 bsize = DEV_BSIZE; 2446 else if (vp->v_mount) 2447 bsize = vp->v_mount->mnt_stat.f_iosize; 2448 else 2449 bsize = size; 2450 2451 offset = (off_t)blkno * bsize; 2452 vmio = (VOP_GETVOBJECT(vp, NULL) == 0) && (vp->v_flag & VOBJBUF); 2453 maxsize = vmio ? size + (offset & PAGE_MASK) : size; 2454 maxsize = imax(maxsize, bsize); 2455 2456 if ((bp = getnewbuf(slpflag, slptimeo, size, maxsize)) == NULL) { 2457 if (slpflag || slptimeo) { 2458 crit_exit(); 2459 return NULL; 2460 } 2461 goto loop; 2462 } 2463 2464 /* 2465 * This code is used to make sure that a buffer is not 2466 * created while the getnewbuf routine is blocked. 2467 * This can be a problem whether the vnode is locked or not. 2468 * If the buffer is created out from under us, we have to 2469 * throw away the one we just created. There is now window 2470 * race because we are safely running in a critical section 2471 * from the point of the duplicate buffer creation through 2472 * to here, and we've locked the buffer. 2473 */ 2474 if (gbincore(vp, blkno)) { 2475 bp->b_flags |= B_INVAL; 2476 brelse(bp); 2477 goto loop; 2478 } 2479 2480 /* 2481 * Insert the buffer into the hash, so that it can 2482 * be found by incore. bgetvp() and bufhash() 2483 * must be synchronized with each other. 2484 */ 2485 bp->b_blkno = bp->b_lblkno = blkno; 2486 bp->b_offset = offset; 2487 2488 bgetvp(vp, bp); 2489 LIST_REMOVE(bp, b_hash); 2490 bh = bufhash(vp, blkno); 2491 LIST_INSERT_HEAD(bh, bp, b_hash); 2492 2493 /* 2494 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 2495 * buffer size starts out as 0, B_CACHE will be set by 2496 * allocbuf() for the VMIO case prior to it testing the 2497 * backing store for validity. 2498 */ 2499 2500 if (vmio) { 2501 bp->b_flags |= B_VMIO; 2502 #if defined(VFS_BIO_DEBUG) 2503 if (vn_canvmio(vp) != TRUE) 2504 printf("getblk: vmioing file type %d???\n", vp->v_type); 2505 #endif 2506 } else { 2507 bp->b_flags &= ~B_VMIO; 2508 } 2509 2510 allocbuf(bp, size); 2511 2512 crit_exit(); 2513 bp->b_flags &= ~B_DONE; 2514 } 2515 return (bp); 2516 } 2517 2518 /* 2519 * geteblk: 2520 * 2521 * Get an empty, disassociated buffer of given size. The buffer is 2522 * initially set to B_INVAL. 2523 * 2524 * critical section protection is not required for the allocbuf() 2525 * call because races are impossible here. 2526 */ 2527 struct buf * 2528 geteblk(int size) 2529 { 2530 struct buf *bp; 2531 int maxsize; 2532 2533 maxsize = (size + BKVAMASK) & ~BKVAMASK; 2534 2535 crit_enter(); 2536 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0) 2537 ; 2538 crit_exit(); 2539 allocbuf(bp, size); 2540 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 2541 return (bp); 2542 } 2543 2544 2545 /* 2546 * allocbuf: 2547 * 2548 * This code constitutes the buffer memory from either anonymous system 2549 * memory (in the case of non-VMIO operations) or from an associated 2550 * VM object (in the case of VMIO operations). This code is able to 2551 * resize a buffer up or down. 2552 * 2553 * Note that this code is tricky, and has many complications to resolve 2554 * deadlock or inconsistant data situations. Tread lightly!!! 2555 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 2556 * the caller. Calling this code willy nilly can result in the loss of data. 2557 * 2558 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 2559 * B_CACHE for the non-VMIO case. 2560 * 2561 * This routine does not need to be called from a critical section but you 2562 * must own the buffer. 2563 */ 2564 int 2565 allocbuf(struct buf *bp, int size) 2566 { 2567 int newbsize, mbsize; 2568 int i; 2569 2570 if (BUF_REFCNT(bp) == 0) 2571 panic("allocbuf: buffer not busy"); 2572 2573 if (bp->b_kvasize < size) 2574 panic("allocbuf: buffer too small"); 2575 2576 if ((bp->b_flags & B_VMIO) == 0) { 2577 caddr_t origbuf; 2578 int origbufsize; 2579 /* 2580 * Just get anonymous memory from the kernel. Don't 2581 * mess with B_CACHE. 2582 */ 2583 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2584 #if !defined(NO_B_MALLOC) 2585 if (bp->b_flags & B_MALLOC) 2586 newbsize = mbsize; 2587 else 2588 #endif 2589 newbsize = round_page(size); 2590 2591 if (newbsize < bp->b_bufsize) { 2592 #if !defined(NO_B_MALLOC) 2593 /* 2594 * malloced buffers are not shrunk 2595 */ 2596 if (bp->b_flags & B_MALLOC) { 2597 if (newbsize) { 2598 bp->b_bcount = size; 2599 } else { 2600 free(bp->b_data, M_BIOBUF); 2601 if (bp->b_bufsize) { 2602 bufmallocspace -= bp->b_bufsize; 2603 bufspacewakeup(); 2604 bp->b_bufsize = 0; 2605 } 2606 bp->b_data = bp->b_kvabase; 2607 bp->b_bcount = 0; 2608 bp->b_flags &= ~B_MALLOC; 2609 } 2610 return 1; 2611 } 2612 #endif 2613 vm_hold_free_pages( 2614 bp, 2615 (vm_offset_t) bp->b_data + newbsize, 2616 (vm_offset_t) bp->b_data + bp->b_bufsize); 2617 } else if (newbsize > bp->b_bufsize) { 2618 #if !defined(NO_B_MALLOC) 2619 /* 2620 * We only use malloced memory on the first allocation. 2621 * and revert to page-allocated memory when the buffer 2622 * grows. 2623 */ 2624 if ( (bufmallocspace < maxbufmallocspace) && 2625 (bp->b_bufsize == 0) && 2626 (mbsize <= PAGE_SIZE/2)) { 2627 2628 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 2629 bp->b_bufsize = mbsize; 2630 bp->b_bcount = size; 2631 bp->b_flags |= B_MALLOC; 2632 bufmallocspace += mbsize; 2633 return 1; 2634 } 2635 #endif 2636 origbuf = NULL; 2637 origbufsize = 0; 2638 #if !defined(NO_B_MALLOC) 2639 /* 2640 * If the buffer is growing on its other-than-first allocation, 2641 * then we revert to the page-allocation scheme. 2642 */ 2643 if (bp->b_flags & B_MALLOC) { 2644 origbuf = bp->b_data; 2645 origbufsize = bp->b_bufsize; 2646 bp->b_data = bp->b_kvabase; 2647 if (bp->b_bufsize) { 2648 bufmallocspace -= bp->b_bufsize; 2649 bufspacewakeup(); 2650 bp->b_bufsize = 0; 2651 } 2652 bp->b_flags &= ~B_MALLOC; 2653 newbsize = round_page(newbsize); 2654 } 2655 #endif 2656 vm_hold_load_pages( 2657 bp, 2658 (vm_offset_t) bp->b_data + bp->b_bufsize, 2659 (vm_offset_t) bp->b_data + newbsize); 2660 #if !defined(NO_B_MALLOC) 2661 if (origbuf) { 2662 bcopy(origbuf, bp->b_data, origbufsize); 2663 free(origbuf, M_BIOBUF); 2664 } 2665 #endif 2666 } 2667 } else { 2668 vm_page_t m; 2669 int desiredpages; 2670 2671 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2672 desiredpages = (size == 0) ? 0 : 2673 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 2674 2675 #if !defined(NO_B_MALLOC) 2676 if (bp->b_flags & B_MALLOC) 2677 panic("allocbuf: VMIO buffer can't be malloced"); 2678 #endif 2679 /* 2680 * Set B_CACHE initially if buffer is 0 length or will become 2681 * 0-length. 2682 */ 2683 if (size == 0 || bp->b_bufsize == 0) 2684 bp->b_flags |= B_CACHE; 2685 2686 if (newbsize < bp->b_bufsize) { 2687 /* 2688 * DEV_BSIZE aligned new buffer size is less then the 2689 * DEV_BSIZE aligned existing buffer size. Figure out 2690 * if we have to remove any pages. 2691 */ 2692 if (desiredpages < bp->b_xio.xio_npages) { 2693 for (i = desiredpages; i < bp->b_xio.xio_npages; i++) { 2694 /* 2695 * the page is not freed here -- it 2696 * is the responsibility of 2697 * vnode_pager_setsize 2698 */ 2699 m = bp->b_xio.xio_pages[i]; 2700 KASSERT(m != bogus_page, 2701 ("allocbuf: bogus page found")); 2702 while (vm_page_sleep_busy(m, TRUE, "biodep")) 2703 ; 2704 2705 bp->b_xio.xio_pages[i] = NULL; 2706 vm_page_unwire(m, 0); 2707 } 2708 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) + 2709 (desiredpages << PAGE_SHIFT), (bp->b_xio.xio_npages - desiredpages)); 2710 bp->b_xio.xio_npages = desiredpages; 2711 } 2712 } else if (size > bp->b_bcount) { 2713 /* 2714 * We are growing the buffer, possibly in a 2715 * byte-granular fashion. 2716 */ 2717 struct vnode *vp; 2718 vm_object_t obj; 2719 vm_offset_t toff; 2720 vm_offset_t tinc; 2721 2722 /* 2723 * Step 1, bring in the VM pages from the object, 2724 * allocating them if necessary. We must clear 2725 * B_CACHE if these pages are not valid for the 2726 * range covered by the buffer. 2727 * 2728 * critical section protection is required to protect 2729 * against interrupts unbusying and freeing pages 2730 * between our vm_page_lookup() and our 2731 * busycheck/wiring call. 2732 */ 2733 vp = bp->b_vp; 2734 VOP_GETVOBJECT(vp, &obj); 2735 2736 crit_enter(); 2737 while (bp->b_xio.xio_npages < desiredpages) { 2738 vm_page_t m; 2739 vm_pindex_t pi; 2740 2741 pi = OFF_TO_IDX(bp->b_offset) + bp->b_xio.xio_npages; 2742 if ((m = vm_page_lookup(obj, pi)) == NULL) { 2743 /* 2744 * note: must allocate system pages 2745 * since blocking here could intefere 2746 * with paging I/O, no matter which 2747 * process we are. 2748 */ 2749 m = vm_page_alloc(obj, pi, VM_ALLOC_NORMAL | VM_ALLOC_SYSTEM); 2750 if (m == NULL) { 2751 vm_wait(); 2752 vm_pageout_deficit += desiredpages - 2753 bp->b_xio.xio_npages; 2754 } else { 2755 vm_page_wire(m); 2756 vm_page_wakeup(m); 2757 bp->b_flags &= ~B_CACHE; 2758 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 2759 ++bp->b_xio.xio_npages; 2760 } 2761 continue; 2762 } 2763 2764 /* 2765 * We found a page. If we have to sleep on it, 2766 * retry because it might have gotten freed out 2767 * from under us. 2768 * 2769 * We can only test PG_BUSY here. Blocking on 2770 * m->busy might lead to a deadlock: 2771 * 2772 * vm_fault->getpages->cluster_read->allocbuf 2773 * 2774 */ 2775 2776 if (vm_page_sleep_busy(m, FALSE, "pgtblk")) 2777 continue; 2778 2779 /* 2780 * We have a good page. Should we wakeup the 2781 * page daemon? 2782 */ 2783 if ((curthread != pagethread) && 2784 ((m->queue - m->pc) == PQ_CACHE) && 2785 ((vmstats.v_free_count + vmstats.v_cache_count) < 2786 (vmstats.v_free_min + vmstats.v_cache_min))) { 2787 pagedaemon_wakeup(); 2788 } 2789 vm_page_flag_clear(m, PG_ZERO); 2790 vm_page_wire(m); 2791 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 2792 ++bp->b_xio.xio_npages; 2793 } 2794 crit_exit(); 2795 2796 /* 2797 * Step 2. We've loaded the pages into the buffer, 2798 * we have to figure out if we can still have B_CACHE 2799 * set. Note that B_CACHE is set according to the 2800 * byte-granular range ( bcount and size ), not the 2801 * aligned range ( newbsize ). 2802 * 2803 * The VM test is against m->valid, which is DEV_BSIZE 2804 * aligned. Needless to say, the validity of the data 2805 * needs to also be DEV_BSIZE aligned. Note that this 2806 * fails with NFS if the server or some other client 2807 * extends the file's EOF. If our buffer is resized, 2808 * B_CACHE may remain set! XXX 2809 */ 2810 2811 toff = bp->b_bcount; 2812 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 2813 2814 while ((bp->b_flags & B_CACHE) && toff < size) { 2815 vm_pindex_t pi; 2816 2817 if (tinc > (size - toff)) 2818 tinc = size - toff; 2819 2820 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 2821 PAGE_SHIFT; 2822 2823 vfs_buf_test_cache( 2824 bp, 2825 bp->b_offset, 2826 toff, 2827 tinc, 2828 bp->b_xio.xio_pages[pi] 2829 ); 2830 toff += tinc; 2831 tinc = PAGE_SIZE; 2832 } 2833 2834 /* 2835 * Step 3, fixup the KVM pmap. Remember that 2836 * bp->b_data is relative to bp->b_offset, but 2837 * bp->b_offset may be offset into the first page. 2838 */ 2839 2840 bp->b_data = (caddr_t) 2841 trunc_page((vm_offset_t)bp->b_data); 2842 pmap_qenter( 2843 (vm_offset_t)bp->b_data, 2844 bp->b_xio.xio_pages, 2845 bp->b_xio.xio_npages 2846 ); 2847 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 2848 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 2849 } 2850 } 2851 if (newbsize < bp->b_bufsize) 2852 bufspacewakeup(); 2853 bp->b_bufsize = newbsize; /* actual buffer allocation */ 2854 bp->b_bcount = size; /* requested buffer size */ 2855 return 1; 2856 } 2857 2858 /* 2859 * biowait: 2860 * 2861 * Wait for buffer I/O completion, returning error status. The buffer 2862 * is left locked and B_DONE on return. B_EINTR is converted into an 2863 * EINTR error and cleared. 2864 */ 2865 int 2866 biowait(struct buf * bp) 2867 { 2868 crit_enter(); 2869 while ((bp->b_flags & B_DONE) == 0) { 2870 if (bp->b_flags & B_READ) 2871 tsleep(bp, 0, "biord", 0); 2872 else 2873 tsleep(bp, 0, "biowr", 0); 2874 } 2875 crit_exit(); 2876 if (bp->b_flags & B_EINTR) { 2877 bp->b_flags &= ~B_EINTR; 2878 return (EINTR); 2879 } 2880 if (bp->b_flags & B_ERROR) { 2881 return (bp->b_error ? bp->b_error : EIO); 2882 } else { 2883 return (0); 2884 } 2885 } 2886 2887 /* 2888 * biodone: 2889 * 2890 * Finish I/O on a buffer, optionally calling a completion function. 2891 * This is usually called from an interrupt so process blocking is 2892 * not allowed. 2893 * 2894 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 2895 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 2896 * assuming B_INVAL is clear. 2897 * 2898 * For the VMIO case, we set B_CACHE if the op was a read and no 2899 * read error occured, or if the op was a write. B_CACHE is never 2900 * set if the buffer is invalid or otherwise uncacheable. 2901 * 2902 * biodone does not mess with B_INVAL, allowing the I/O routine or the 2903 * initiator to leave B_INVAL set to brelse the buffer out of existance 2904 * in the biodone routine. 2905 * 2906 * b_dev is required to be reinitialized prior to the top level strategy 2907 * call in a device stack. To avoid improper reuse, biodone() sets 2908 * b_dev to NODEV. 2909 */ 2910 void 2911 biodone(struct buf *bp) 2912 { 2913 int error; 2914 2915 crit_enter(); 2916 2917 KASSERT(BUF_REFCNTNB(bp) > 0, ("biodone: bp %p not busy %d", bp, BUF_REFCNTNB(bp))); 2918 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 2919 biodone_t *biodone_func; 2920 2921 bp->b_flags |= B_DONE; 2922 bp->b_dev = NODEV; 2923 runningbufwakeup(bp); 2924 2925 if (bp->b_flags & B_FREEBUF) { 2926 brelse(bp); 2927 crit_exit(); 2928 return; 2929 } 2930 2931 if ((bp->b_flags & B_READ) == 0) { 2932 vwakeup(bp); 2933 } 2934 2935 /* call optional completion function if requested */ 2936 if (bp->b_iodone != NULL) { 2937 biodone_func = bp->b_iodone; 2938 bp->b_iodone = NULL; 2939 (*biodone_func) (bp); 2940 crit_exit(); 2941 return; 2942 } 2943 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_complete) 2944 (*bioops.io_complete)(bp); 2945 2946 if (bp->b_flags & B_VMIO) { 2947 int i; 2948 vm_ooffset_t foff; 2949 vm_page_t m; 2950 vm_object_t obj; 2951 int iosize; 2952 struct vnode *vp = bp->b_vp; 2953 2954 error = VOP_GETVOBJECT(vp, &obj); 2955 2956 #if defined(VFS_BIO_DEBUG) 2957 if (vp->v_holdcnt == 0) { 2958 panic("biodone: zero vnode hold count"); 2959 } 2960 2961 if (error) { 2962 panic("biodone: missing VM object"); 2963 } 2964 2965 if ((vp->v_flag & VOBJBUF) == 0) { 2966 panic("biodone: vnode is not setup for merged cache"); 2967 } 2968 #endif 2969 2970 foff = bp->b_offset; 2971 KASSERT(bp->b_offset != NOOFFSET, 2972 ("biodone: no buffer offset")); 2973 2974 if (error) { 2975 panic("biodone: no object"); 2976 } 2977 #if defined(VFS_BIO_DEBUG) 2978 if (obj->paging_in_progress < bp->b_xio.xio_npages) { 2979 printf("biodone: paging in progress(%d) < bp->b_xio.xio_npages(%d)\n", 2980 obj->paging_in_progress, bp->b_xio.xio_npages); 2981 } 2982 #endif 2983 2984 /* 2985 * Set B_CACHE if the op was a normal read and no error 2986 * occured. B_CACHE is set for writes in the b*write() 2987 * routines. 2988 */ 2989 iosize = bp->b_bcount - bp->b_resid; 2990 if ((bp->b_flags & (B_READ|B_FREEBUF|B_INVAL|B_NOCACHE|B_ERROR)) == B_READ) { 2991 bp->b_flags |= B_CACHE; 2992 } 2993 2994 for (i = 0; i < bp->b_xio.xio_npages; i++) { 2995 int bogusflag = 0; 2996 int resid; 2997 2998 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 2999 if (resid > iosize) 3000 resid = iosize; 3001 3002 /* 3003 * cleanup bogus pages, restoring the originals. Since 3004 * the originals should still be wired, we don't have 3005 * to worry about interrupt/freeing races destroying 3006 * the VM object association. 3007 */ 3008 m = bp->b_xio.xio_pages[i]; 3009 if (m == bogus_page) { 3010 bogusflag = 1; 3011 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3012 if (m == NULL) 3013 panic("biodone: page disappeared"); 3014 bp->b_xio.xio_pages[i] = m; 3015 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3016 bp->b_xio.xio_pages, bp->b_xio.xio_npages); 3017 } 3018 #if defined(VFS_BIO_DEBUG) 3019 if (OFF_TO_IDX(foff) != m->pindex) { 3020 printf( 3021 "biodone: foff(%lu)/m->pindex(%d) mismatch\n", 3022 (unsigned long)foff, m->pindex); 3023 } 3024 #endif 3025 3026 /* 3027 * In the write case, the valid and clean bits are 3028 * already changed correctly ( see bdwrite() ), so we 3029 * only need to do this here in the read case. 3030 */ 3031 if ((bp->b_flags & B_READ) && !bogusflag && resid > 0) { 3032 vfs_page_set_valid(bp, foff, i, m); 3033 } 3034 vm_page_flag_clear(m, PG_ZERO); 3035 3036 /* 3037 * when debugging new filesystems or buffer I/O methods, this 3038 * is the most common error that pops up. if you see this, you 3039 * have not set the page busy flag correctly!!! 3040 */ 3041 if (m->busy == 0) { 3042 printf("biodone: page busy < 0, " 3043 "pindex: %d, foff: 0x(%x,%x), " 3044 "resid: %d, index: %d\n", 3045 (int) m->pindex, (int)(foff >> 32), 3046 (int) foff & 0xffffffff, resid, i); 3047 if (!vn_isdisk(vp, NULL)) 3048 printf(" iosize: %ld, lblkno: %d, flags: 0x%lx, npages: %d\n", 3049 bp->b_vp->v_mount->mnt_stat.f_iosize, 3050 (int) bp->b_lblkno, 3051 bp->b_flags, bp->b_xio.xio_npages); 3052 else 3053 printf(" VDEV, lblkno: %d, flags: 0x%lx, npages: %d\n", 3054 (int) bp->b_lblkno, 3055 bp->b_flags, bp->b_xio.xio_npages); 3056 printf(" valid: 0x%x, dirty: 0x%x, wired: %d\n", 3057 m->valid, m->dirty, m->wire_count); 3058 panic("biodone: page busy < 0"); 3059 } 3060 vm_page_io_finish(m); 3061 vm_object_pip_subtract(obj, 1); 3062 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3063 iosize -= resid; 3064 } 3065 if (obj) 3066 vm_object_pip_wakeupn(obj, 0); 3067 } 3068 3069 /* 3070 * For asynchronous completions, release the buffer now. The brelse 3071 * will do a wakeup there if necessary - so no need to do a wakeup 3072 * here in the async case. The sync case always needs to do a wakeup. 3073 */ 3074 3075 if (bp->b_flags & B_ASYNC) { 3076 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR | B_RELBUF)) != 0) 3077 brelse(bp); 3078 else 3079 bqrelse(bp); 3080 } else { 3081 wakeup(bp); 3082 } 3083 crit_exit(); 3084 } 3085 3086 /* 3087 * vfs_unbusy_pages: 3088 * 3089 * This routine is called in lieu of iodone in the case of 3090 * incomplete I/O. This keeps the busy status for pages 3091 * consistant. 3092 */ 3093 void 3094 vfs_unbusy_pages(struct buf *bp) 3095 { 3096 int i; 3097 3098 runningbufwakeup(bp); 3099 if (bp->b_flags & B_VMIO) { 3100 struct vnode *vp = bp->b_vp; 3101 vm_object_t obj; 3102 3103 VOP_GETVOBJECT(vp, &obj); 3104 3105 for (i = 0; i < bp->b_xio.xio_npages; i++) { 3106 vm_page_t m = bp->b_xio.xio_pages[i]; 3107 3108 /* 3109 * When restoring bogus changes the original pages 3110 * should still be wired, so we are in no danger of 3111 * losing the object association and do not need 3112 * critical section protection particularly. 3113 */ 3114 if (m == bogus_page) { 3115 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 3116 if (!m) { 3117 panic("vfs_unbusy_pages: page missing"); 3118 } 3119 bp->b_xio.xio_pages[i] = m; 3120 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3121 bp->b_xio.xio_pages, bp->b_xio.xio_npages); 3122 } 3123 vm_object_pip_subtract(obj, 1); 3124 vm_page_flag_clear(m, PG_ZERO); 3125 vm_page_io_finish(m); 3126 } 3127 vm_object_pip_wakeupn(obj, 0); 3128 } 3129 } 3130 3131 /* 3132 * vfs_page_set_valid: 3133 * 3134 * Set the valid bits in a page based on the supplied offset. The 3135 * range is restricted to the buffer's size. 3136 * 3137 * This routine is typically called after a read completes. 3138 */ 3139 static void 3140 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m) 3141 { 3142 vm_ooffset_t soff, eoff; 3143 3144 /* 3145 * Start and end offsets in buffer. eoff - soff may not cross a 3146 * page boundry or cross the end of the buffer. The end of the 3147 * buffer, in this case, is our file EOF, not the allocation size 3148 * of the buffer. 3149 */ 3150 soff = off; 3151 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3152 if (eoff > bp->b_offset + bp->b_bcount) 3153 eoff = bp->b_offset + bp->b_bcount; 3154 3155 /* 3156 * Set valid range. This is typically the entire buffer and thus the 3157 * entire page. 3158 */ 3159 if (eoff > soff) { 3160 vm_page_set_validclean( 3161 m, 3162 (vm_offset_t) (soff & PAGE_MASK), 3163 (vm_offset_t) (eoff - soff) 3164 ); 3165 } 3166 } 3167 3168 /* 3169 * vfs_busy_pages: 3170 * 3171 * This routine is called before a device strategy routine. 3172 * It is used to tell the VM system that paging I/O is in 3173 * progress, and treat the pages associated with the buffer 3174 * almost as being PG_BUSY. Also the object 'paging_in_progress' 3175 * flag is handled to make sure that the object doesn't become 3176 * inconsistant. 3177 * 3178 * Since I/O has not been initiated yet, certain buffer flags 3179 * such as B_ERROR or B_INVAL may be in an inconsistant state 3180 * and should be ignored. 3181 */ 3182 void 3183 vfs_busy_pages(struct buf *bp, int clear_modify) 3184 { 3185 int i, bogus; 3186 3187 if (bp->b_flags & B_VMIO) { 3188 struct vnode *vp = bp->b_vp; 3189 vm_object_t obj; 3190 vm_ooffset_t foff; 3191 3192 VOP_GETVOBJECT(vp, &obj); 3193 foff = bp->b_offset; 3194 KASSERT(bp->b_offset != NOOFFSET, 3195 ("vfs_busy_pages: no buffer offset")); 3196 vfs_setdirty(bp); 3197 3198 retry: 3199 for (i = 0; i < bp->b_xio.xio_npages; i++) { 3200 vm_page_t m = bp->b_xio.xio_pages[i]; 3201 if (vm_page_sleep_busy(m, FALSE, "vbpage")) 3202 goto retry; 3203 } 3204 3205 bogus = 0; 3206 for (i = 0; i < bp->b_xio.xio_npages; i++) { 3207 vm_page_t m = bp->b_xio.xio_pages[i]; 3208 3209 vm_page_flag_clear(m, PG_ZERO); 3210 if ((bp->b_flags & B_CLUSTER) == 0) { 3211 vm_object_pip_add(obj, 1); 3212 vm_page_io_start(m); 3213 } 3214 3215 /* 3216 * When readying a buffer for a read ( i.e 3217 * clear_modify == 0 ), it is important to do 3218 * bogus_page replacement for valid pages in 3219 * partially instantiated buffers. Partially 3220 * instantiated buffers can, in turn, occur when 3221 * reconstituting a buffer from its VM backing store 3222 * base. We only have to do this if B_CACHE is 3223 * clear ( which causes the I/O to occur in the 3224 * first place ). The replacement prevents the read 3225 * I/O from overwriting potentially dirty VM-backed 3226 * pages. XXX bogus page replacement is, uh, bogus. 3227 * It may not work properly with small-block devices. 3228 * We need to find a better way. 3229 */ 3230 3231 vm_page_protect(m, VM_PROT_NONE); 3232 if (clear_modify) 3233 vfs_page_set_valid(bp, foff, i, m); 3234 else if (m->valid == VM_PAGE_BITS_ALL && 3235 (bp->b_flags & B_CACHE) == 0) { 3236 bp->b_xio.xio_pages[i] = bogus_page; 3237 bogus++; 3238 } 3239 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3240 } 3241 if (bogus) 3242 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3243 bp->b_xio.xio_pages, bp->b_xio.xio_npages); 3244 } 3245 3246 /* 3247 * This is the easiest place to put the process accounting for the I/O 3248 * for now. 3249 */ 3250 { 3251 struct proc *p; 3252 3253 if ((p = curthread->td_proc) != NULL) { 3254 if (bp->b_flags & B_READ) 3255 p->p_stats->p_ru.ru_inblock++; 3256 else 3257 p->p_stats->p_ru.ru_oublock++; 3258 } 3259 } 3260 } 3261 3262 /* 3263 * vfs_clean_pages: 3264 * 3265 * Tell the VM system that the pages associated with this buffer 3266 * are clean. This is used for delayed writes where the data is 3267 * going to go to disk eventually without additional VM intevention. 3268 * 3269 * Note that while we only really need to clean through to b_bcount, we 3270 * just go ahead and clean through to b_bufsize. 3271 */ 3272 static void 3273 vfs_clean_pages(struct buf *bp) 3274 { 3275 int i; 3276 3277 if (bp->b_flags & B_VMIO) { 3278 vm_ooffset_t foff; 3279 3280 foff = bp->b_offset; 3281 KASSERT(bp->b_offset != NOOFFSET, 3282 ("vfs_clean_pages: no buffer offset")); 3283 for (i = 0; i < bp->b_xio.xio_npages; i++) { 3284 vm_page_t m = bp->b_xio.xio_pages[i]; 3285 vm_ooffset_t noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3286 vm_ooffset_t eoff = noff; 3287 3288 if (eoff > bp->b_offset + bp->b_bufsize) 3289 eoff = bp->b_offset + bp->b_bufsize; 3290 vfs_page_set_valid(bp, foff, i, m); 3291 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3292 foff = noff; 3293 } 3294 } 3295 } 3296 3297 /* 3298 * vfs_bio_set_validclean: 3299 * 3300 * Set the range within the buffer to valid and clean. The range is 3301 * relative to the beginning of the buffer, b_offset. Note that b_offset 3302 * itself may be offset from the beginning of the first page. 3303 */ 3304 3305 void 3306 vfs_bio_set_validclean(struct buf *bp, int base, int size) 3307 { 3308 if (bp->b_flags & B_VMIO) { 3309 int i; 3310 int n; 3311 3312 /* 3313 * Fixup base to be relative to beginning of first page. 3314 * Set initial n to be the maximum number of bytes in the 3315 * first page that can be validated. 3316 */ 3317 3318 base += (bp->b_offset & PAGE_MASK); 3319 n = PAGE_SIZE - (base & PAGE_MASK); 3320 3321 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_xio.xio_npages; ++i) { 3322 vm_page_t m = bp->b_xio.xio_pages[i]; 3323 3324 if (n > size) 3325 n = size; 3326 3327 vm_page_set_validclean(m, base & PAGE_MASK, n); 3328 base += n; 3329 size -= n; 3330 n = PAGE_SIZE; 3331 } 3332 } 3333 } 3334 3335 /* 3336 * vfs_bio_clrbuf: 3337 * 3338 * Clear a buffer. This routine essentially fakes an I/O, so we need 3339 * to clear B_ERROR and B_INVAL. 3340 * 3341 * Note that while we only theoretically need to clear through b_bcount, 3342 * we go ahead and clear through b_bufsize. 3343 */ 3344 3345 void 3346 vfs_bio_clrbuf(struct buf *bp) 3347 { 3348 int i, mask = 0; 3349 caddr_t sa, ea; 3350 if ((bp->b_flags & (B_VMIO | B_MALLOC)) == B_VMIO) { 3351 bp->b_flags &= ~(B_INVAL|B_ERROR); 3352 if ((bp->b_xio.xio_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 3353 (bp->b_offset & PAGE_MASK) == 0) { 3354 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 3355 if ((bp->b_xio.xio_pages[0]->valid & mask) == mask) { 3356 bp->b_resid = 0; 3357 return; 3358 } 3359 if (((bp->b_xio.xio_pages[0]->flags & PG_ZERO) == 0) && 3360 ((bp->b_xio.xio_pages[0]->valid & mask) == 0)) { 3361 bzero(bp->b_data, bp->b_bufsize); 3362 bp->b_xio.xio_pages[0]->valid |= mask; 3363 bp->b_resid = 0; 3364 return; 3365 } 3366 } 3367 ea = sa = bp->b_data; 3368 for(i=0;i<bp->b_xio.xio_npages;i++,sa=ea) { 3369 int j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; 3370 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); 3371 ea = (caddr_t)(vm_offset_t)ulmin( 3372 (u_long)(vm_offset_t)ea, 3373 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); 3374 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 3375 if ((bp->b_xio.xio_pages[i]->valid & mask) == mask) 3376 continue; 3377 if ((bp->b_xio.xio_pages[i]->valid & mask) == 0) { 3378 if ((bp->b_xio.xio_pages[i]->flags & PG_ZERO) == 0) { 3379 bzero(sa, ea - sa); 3380 } 3381 } else { 3382 for (; sa < ea; sa += DEV_BSIZE, j++) { 3383 if (((bp->b_xio.xio_pages[i]->flags & PG_ZERO) == 0) && 3384 (bp->b_xio.xio_pages[i]->valid & (1<<j)) == 0) 3385 bzero(sa, DEV_BSIZE); 3386 } 3387 } 3388 bp->b_xio.xio_pages[i]->valid |= mask; 3389 vm_page_flag_clear(bp->b_xio.xio_pages[i], PG_ZERO); 3390 } 3391 bp->b_resid = 0; 3392 } else { 3393 clrbuf(bp); 3394 } 3395 } 3396 3397 /* 3398 * vm_hold_load_pages: 3399 * 3400 * Load pages into the buffer's address space. The pages are 3401 * allocated from the kernel object in order to reduce interference 3402 * with the any VM paging I/O activity. The range of loaded 3403 * pages will be wired. 3404 * 3405 * If a page cannot be allocated, the 'pagedaemon' is woken up to 3406 * retrieve the full range (to - from) of pages. 3407 * 3408 */ 3409 void 3410 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 3411 { 3412 vm_offset_t pg; 3413 vm_page_t p; 3414 int index; 3415 3416 to = round_page(to); 3417 from = round_page(from); 3418 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3419 3420 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3421 3422 tryagain: 3423 3424 /* 3425 * Note: must allocate system pages since blocking here 3426 * could intefere with paging I/O, no matter which 3427 * process we are. 3428 */ 3429 p = vm_page_alloc(kernel_object, 3430 ((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 3431 VM_ALLOC_NORMAL | VM_ALLOC_SYSTEM); 3432 if (!p) { 3433 vm_pageout_deficit += (to - from) >> PAGE_SHIFT; 3434 vm_wait(); 3435 goto tryagain; 3436 } 3437 vm_page_wire(p); 3438 p->valid = VM_PAGE_BITS_ALL; 3439 vm_page_flag_clear(p, PG_ZERO); 3440 pmap_kenter(pg, VM_PAGE_TO_PHYS(p)); 3441 bp->b_xio.xio_pages[index] = p; 3442 vm_page_wakeup(p); 3443 } 3444 bp->b_xio.xio_npages = index; 3445 } 3446 3447 /* 3448 * vm_hold_free_pages: 3449 * 3450 * Return pages associated with the buffer back to the VM system. 3451 * 3452 * The range of pages underlying the buffer's address space will 3453 * be unmapped and un-wired. 3454 */ 3455 void 3456 vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 3457 { 3458 vm_offset_t pg; 3459 vm_page_t p; 3460 int index, newnpages; 3461 3462 from = round_page(from); 3463 to = round_page(to); 3464 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3465 3466 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3467 p = bp->b_xio.xio_pages[index]; 3468 if (p && (index < bp->b_xio.xio_npages)) { 3469 if (p->busy) { 3470 printf("vm_hold_free_pages: blkno: %d, lblkno: %d\n", 3471 bp->b_blkno, bp->b_lblkno); 3472 } 3473 bp->b_xio.xio_pages[index] = NULL; 3474 pmap_kremove(pg); 3475 vm_page_busy(p); 3476 vm_page_unwire(p, 0); 3477 vm_page_free(p); 3478 } 3479 } 3480 bp->b_xio.xio_npages = newnpages; 3481 } 3482 3483 /* 3484 * vmapbuf: 3485 * 3486 * Map an IO request into kernel virtual address space. 3487 * 3488 * All requests are (re)mapped into kernel VA space. 3489 * Notice that we use b_bufsize for the size of the buffer 3490 * to be mapped. b_bcount might be modified by the driver. 3491 */ 3492 int 3493 vmapbuf(struct buf *bp) 3494 { 3495 caddr_t addr, v, kva; 3496 vm_paddr_t pa; 3497 int pidx; 3498 int i; 3499 struct vm_page *m; 3500 3501 if ((bp->b_flags & B_PHYS) == 0) 3502 panic("vmapbuf"); 3503 if (bp->b_bufsize < 0) 3504 return (-1); 3505 for (v = bp->b_saveaddr, 3506 addr = (caddr_t)trunc_page((vm_offset_t)bp->b_data), 3507 pidx = 0; 3508 addr < bp->b_data + bp->b_bufsize; 3509 addr += PAGE_SIZE, v += PAGE_SIZE, pidx++) { 3510 /* 3511 * Do the vm_fault if needed; do the copy-on-write thing 3512 * when reading stuff off device into memory. 3513 */ 3514 retry: 3515 i = vm_fault_quick((addr >= bp->b_data) ? addr : bp->b_data, 3516 (bp->b_flags&B_READ)?(VM_PROT_READ|VM_PROT_WRITE):VM_PROT_READ); 3517 if (i < 0) { 3518 for (i = 0; i < pidx; ++i) { 3519 vm_page_unhold(bp->b_xio.xio_pages[i]); 3520 bp->b_xio.xio_pages[i] = NULL; 3521 } 3522 return(-1); 3523 } 3524 3525 /* 3526 * WARNING! If sparc support is MFCd in the future this will 3527 * have to be changed from pmap_kextract() to pmap_extract() 3528 * ala -current. 3529 */ 3530 #ifdef __sparc64__ 3531 #error "If MFCing sparc support use pmap_extract" 3532 #endif 3533 pa = pmap_kextract((vm_offset_t)addr); 3534 if (pa == 0) { 3535 printf("vmapbuf: warning, race against user address during I/O"); 3536 goto retry; 3537 } 3538 m = PHYS_TO_VM_PAGE(pa); 3539 vm_page_hold(m); 3540 bp->b_xio.xio_pages[pidx] = m; 3541 } 3542 if (pidx > btoc(MAXPHYS)) 3543 panic("vmapbuf: mapped more than MAXPHYS"); 3544 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_xio.xio_pages, pidx); 3545 3546 kva = bp->b_saveaddr; 3547 bp->b_xio.xio_npages = pidx; 3548 bp->b_saveaddr = bp->b_data; 3549 bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK); 3550 return(0); 3551 } 3552 3553 /* 3554 * vunmapbuf: 3555 * 3556 * Free the io map PTEs associated with this IO operation. 3557 * We also invalidate the TLB entries and restore the original b_addr. 3558 */ 3559 void 3560 vunmapbuf(struct buf *bp) 3561 { 3562 int pidx; 3563 int npages; 3564 vm_page_t *m; 3565 3566 if ((bp->b_flags & B_PHYS) == 0) 3567 panic("vunmapbuf"); 3568 3569 npages = bp->b_xio.xio_npages; 3570 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), 3571 npages); 3572 m = bp->b_xio.xio_pages; 3573 for (pidx = 0; pidx < npages; pidx++) 3574 vm_page_unhold(*m++); 3575 3576 bp->b_data = bp->b_saveaddr; 3577 } 3578 3579 /* 3580 * print out statistics from the current status of the buffer pool 3581 * this can be toggeled by the system control option debug.syncprt 3582 */ 3583 #ifdef DEBUG 3584 void 3585 vfs_bufstats(void) 3586 { 3587 int i, j, count; 3588 struct buf *bp; 3589 struct bqueues *dp; 3590 int counts[(MAXBSIZE / PAGE_SIZE) + 1]; 3591 static char *bname[3] = { "LOCKED", "LRU", "AGE" }; 3592 3593 for (dp = bufqueues, i = 0; dp < &bufqueues[3]; dp++, i++) { 3594 count = 0; 3595 for (j = 0; j <= MAXBSIZE/PAGE_SIZE; j++) 3596 counts[j] = 0; 3597 crit_enter(); 3598 TAILQ_FOREACH(bp, dp, b_freelist) { 3599 counts[bp->b_bufsize/PAGE_SIZE]++; 3600 count++; 3601 } 3602 crit_exit(); 3603 printf("%s: total-%d", bname[i], count); 3604 for (j = 0; j <= MAXBSIZE/PAGE_SIZE; j++) 3605 if (counts[j] != 0) 3606 printf(", %d-%d", j * PAGE_SIZE, counts[j]); 3607 printf("\n"); 3608 } 3609 } 3610 #endif 3611 3612 #include "opt_ddb.h" 3613 #ifdef DDB 3614 #include <ddb/ddb.h> 3615 3616 DB_SHOW_COMMAND(buffer, db_show_buffer) 3617 { 3618 /* get args */ 3619 struct buf *bp = (struct buf *)addr; 3620 3621 if (!have_addr) { 3622 db_printf("usage: show buffer <addr>\n"); 3623 return; 3624 } 3625 3626 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS); 3627 db_printf("b_error = %d, b_bufsize = %ld, b_bcount = %ld, " 3628 "b_resid = %ld\nb_dev = (%d,%d), b_data = %p, " 3629 "b_blkno = %d, b_pblkno = %d\n", 3630 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 3631 major(bp->b_dev), minor(bp->b_dev), 3632 bp->b_data, bp->b_blkno, bp->b_pblkno); 3633 if (bp->b_xio.xio_npages) { 3634 int i; 3635 db_printf("b_xio.xio_npages = %d, pages(OBJ, IDX, PA): ", 3636 bp->b_xio.xio_npages); 3637 for (i = 0; i < bp->b_xio.xio_npages; i++) { 3638 vm_page_t m; 3639 m = bp->b_xio.xio_pages[i]; 3640 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 3641 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 3642 if ((i + 1) < bp->b_xio.xio_npages) 3643 db_printf(","); 3644 } 3645 db_printf("\n"); 3646 } 3647 } 3648 #endif /* DDB */ 3649