32#include <sys/buf.h> 33#include <sys/eventhandler.h> 34#include <sys/lock.h> 35#include <sys/malloc.h> 36#include <sys/mount.h> 37#include <sys/kernel.h> 38#include <sys/kthread.h> 39#include <sys/proc.h> 40#include <sys/reboot.h> 41#include <sys/resourcevar.h> 42#include <sys/sysctl.h> 43#include <sys/vmmeter.h> 44#include <sys/vnode.h> 45#include <vm/vm.h> 46#include <vm/vm_param.h> 47#include <vm/vm_kern.h> 48#include <vm/vm_pageout.h> 49#include <vm/vm_page.h> 50#include <vm/vm_object.h> 51#include <vm/vm_extern.h> 52#include <vm/vm_map.h> 53 54static MALLOC_DEFINE(M_BIOBUF, "BIO buffer", "BIO buffer"); 55 56struct bio_ops bioops; /* I/O operation notification */ 57 58struct buf *buf; /* buffer header pool */ 59struct swqueue bswlist; 60struct simplelock buftimelock; /* Interlock on setting prio and timo */ 61 62static void vm_hold_free_pages(struct buf * bp, vm_offset_t from, 63 vm_offset_t to); 64static void vm_hold_load_pages(struct buf * bp, vm_offset_t from, 65 vm_offset_t to); 66static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, 67 int pageno, vm_page_t m); 68static void vfs_clean_pages(struct buf * bp); 69static void vfs_setdirty(struct buf *bp); 70static void vfs_vmio_release(struct buf *bp); 71static void vfs_backgroundwritedone(struct buf *bp); 72static int flushbufqueues(void); 73 74static int bd_request; 75 76static void buf_daemon __P((void)); 77/* 78 * bogus page -- for I/O to/from partially complete buffers 79 * this is a temporary solution to the problem, but it is not 80 * really that bad. it would be better to split the buffer 81 * for input in the case of buffers partially already in memory, 82 * but the code is intricate enough already. 83 */ 84vm_page_t bogus_page; 85int runningbufspace; 86int vmiodirenable = FALSE; 87static vm_offset_t bogus_offset; 88 89static int bufspace, maxbufspace, 90 bufmallocspace, maxbufmallocspace, lobufspace, hibufspace; 91static int bufreusecnt, bufdefragcnt, buffreekvacnt; 92static int maxbdrun; 93static int needsbuffer; 94static int numdirtybuffers, hidirtybuffers; 95static int numfreebuffers, lofreebuffers, hifreebuffers; 96static int getnewbufcalls; 97static int getnewbufrestarts; 98 99SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, 100 &numdirtybuffers, 0, ""); 101SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, 102 &hidirtybuffers, 0, ""); 103SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, 104 &numfreebuffers, 0, ""); 105SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, 106 &lofreebuffers, 0, ""); 107SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, 108 &hifreebuffers, 0, ""); 109SYSCTL_INT(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, 110 &runningbufspace, 0, ""); 111SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, 112 &maxbufspace, 0, ""); 113SYSCTL_INT(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, 114 &hibufspace, 0, ""); 115SYSCTL_INT(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, 116 &lobufspace, 0, ""); 117SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, 118 &bufspace, 0, ""); 119SYSCTL_INT(_vfs, OID_AUTO, maxbdrun, CTLFLAG_RW, 120 &maxbdrun, 0, ""); 121SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, 122 &maxbufmallocspace, 0, ""); 123SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, 124 &bufmallocspace, 0, ""); 125SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, 126 &getnewbufcalls, 0, ""); 127SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, 128 &getnewbufrestarts, 0, ""); 129SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, 130 &vmiodirenable, 0, ""); 131SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, 132 &bufdefragcnt, 0, ""); 133SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, 134 &buffreekvacnt, 0, ""); 135SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, 136 &bufreusecnt, 0, ""); 137 138static int bufhashmask; 139static LIST_HEAD(bufhashhdr, buf) *bufhashtbl, invalhash; 140struct bqueues bufqueues[BUFFER_QUEUES] = { { 0 } }; 141char *buf_wmesg = BUF_WMESG; 142 143extern int vm_swap_size; 144 145#define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 146#define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */ 147#define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ 148#define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 149 150/* 151 * Buffer hash table code. Note that the logical block scans linearly, which 152 * gives us some L1 cache locality. 153 */ 154 155static __inline 156struct bufhashhdr * 157bufhash(struct vnode *vnp, daddr_t bn) 158{ 159 return(&bufhashtbl[(((uintptr_t)(vnp) >> 7) + (int)bn) & bufhashmask]); 160} 161 162/* 163 * numdirtywakeup: 164 * 165 * If someone is blocked due to there being too many dirty buffers, 166 * and numdirtybuffers is now reasonable, wake them up. 167 */ 168 169static __inline void 170numdirtywakeup(void) 171{ 172 if (numdirtybuffers < hidirtybuffers) { 173 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) { 174 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH; 175 wakeup(&needsbuffer); 176 } 177 } 178} 179 180/* 181 * bufspacewakeup: 182 * 183 * Called when buffer space is potentially available for recovery. 184 * getnewbuf() will block on this flag when it is unable to free 185 * sufficient buffer space. Buffer space becomes recoverable when 186 * bp's get placed back in the queues. 187 */ 188 189static __inline void 190bufspacewakeup(void) 191{ 192 /* 193 * If someone is waiting for BUF space, wake them up. Even 194 * though we haven't freed the kva space yet, the waiting 195 * process will be able to now. 196 */ 197 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) { 198 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE; 199 wakeup(&needsbuffer); 200 } 201} 202 203/* 204 * bufcountwakeup: 205 * 206 * Called when a buffer has been added to one of the free queues to 207 * account for the buffer and to wakeup anyone waiting for free buffers. 208 * This typically occurs when large amounts of metadata are being handled 209 * by the buffer cache ( else buffer space runs out first, usually ). 210 */ 211 212static __inline void 213bufcountwakeup(void) 214{ 215 ++numfreebuffers; 216 if (needsbuffer) { 217 needsbuffer &= ~VFS_BIO_NEED_ANY; 218 if (numfreebuffers >= hifreebuffers) 219 needsbuffer &= ~VFS_BIO_NEED_FREE; 220 wakeup(&needsbuffer); 221 } 222} 223 224/* 225 * vfs_buf_test_cache: 226 * 227 * Called when a buffer is extended. This function clears the B_CACHE 228 * bit if the newly extended portion of the buffer does not contain 229 * valid data. 230 */ 231static __inline__ 232void 233vfs_buf_test_cache(struct buf *bp, 234 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 235 vm_page_t m) 236{ 237 if (bp->b_flags & B_CACHE) { 238 int base = (foff + off) & PAGE_MASK; 239 if (vm_page_is_valid(m, base, size) == 0) 240 bp->b_flags &= ~B_CACHE; 241 } 242} 243 244static __inline__ 245void 246bd_wakeup(int dirtybuflevel) 247{ 248 if (numdirtybuffers >= dirtybuflevel && bd_request == 0) { 249 bd_request = 1; 250 wakeup(&bd_request); 251 } 252} 253 254/* 255 * bd_speedup - speedup the buffer cache flushing code 256 */ 257 258static __inline__ 259void 260bd_speedup(void) 261{ 262 bd_wakeup(1); 263} 264 265/* 266 * Initialize buffer headers and related structures. 267 */ 268 269caddr_t 270bufhashinit(caddr_t vaddr) 271{ 272 /* first, make a null hash table */ 273 for (bufhashmask = 8; bufhashmask < nbuf / 4; bufhashmask <<= 1) 274 ; 275 bufhashtbl = (void *)vaddr; 276 vaddr = vaddr + sizeof(*bufhashtbl) * bufhashmask; 277 --bufhashmask; 278 return(vaddr); 279} 280 281void 282bufinit(void) 283{ 284 struct buf *bp; 285 int i; 286 287 TAILQ_INIT(&bswlist); 288 LIST_INIT(&invalhash); 289 simple_lock_init(&buftimelock); 290 291 for (i = 0; i <= bufhashmask; i++) 292 LIST_INIT(&bufhashtbl[i]); 293 294 /* next, make a null set of free lists */ 295 for (i = 0; i < BUFFER_QUEUES; i++) 296 TAILQ_INIT(&bufqueues[i]); 297 298 /* finally, initialize each buffer header and stick on empty q */ 299 for (i = 0; i < nbuf; i++) { 300 bp = &buf[i]; 301 bzero(bp, sizeof *bp); 302 bp->b_flags = B_INVAL; /* we're just an empty header */ 303 bp->b_dev = NODEV; 304 bp->b_rcred = NOCRED; 305 bp->b_wcred = NOCRED; 306 bp->b_qindex = QUEUE_EMPTY; 307 bp->b_xflags = 0; 308 LIST_INIT(&bp->b_dep); 309 BUF_LOCKINIT(bp); 310 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 311 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 312 } 313 314 /* 315 * maxbufspace is the absolute maximum amount of buffer space we are 316 * allowed to reserve in KVM and in real terms. The absolute maximum 317 * is nominally used by buf_daemon. hibufspace is the nominal maximum 318 * used by most other processes. The differential is required to 319 * ensure that buf_daemon is able to run when other processes might 320 * be blocked waiting for buffer space. 321 * 322 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 323 * this may result in KVM fragmentation which is not handled optimally 324 * by the system. 325 */ 326 maxbufspace = nbuf * BKVASIZE; 327 hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 328 lobufspace = hibufspace - MAXBSIZE; 329 330/* 331 * Limit the amount of malloc memory since it is wired permanently into 332 * the kernel space. Even though this is accounted for in the buffer 333 * allocation, we don't want the malloced region to grow uncontrolled. 334 * The malloc scheme improves memory utilization significantly on average 335 * (small) directories. 336 */ 337 maxbufmallocspace = hibufspace / 20; 338 339/* 340 * Reduce the chance of a deadlock occuring by limiting the number 341 * of delayed-write dirty buffers we allow to stack up. 342 */ 343 hidirtybuffers = nbuf / 4 + 20; 344 numdirtybuffers = 0; 345/* 346 * To support extreme low-memory systems, make sure hidirtybuffers cannot 347 * eat up all available buffer space. This occurs when our minimum cannot 348 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 349 * BKVASIZE'd (8K) buffers. 350 */ 351 while (hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 352 hidirtybuffers >>= 1; 353 } 354 355/* 356 * Try to keep the number of free buffers in the specified range, 357 * and give special processes (e.g. like buf_daemon) access to an 358 * emergency reserve. 359 */ 360 lofreebuffers = nbuf / 18 + 5; 361 hifreebuffers = 2 * lofreebuffers; 362 numfreebuffers = nbuf; 363 364/* 365 * Maximum number of async ops initiated per buf_daemon loop. This is 366 * somewhat of a hack at the moment, we really need to limit ourselves 367 * based on the number of bytes of I/O in-transit that were initiated 368 * from buf_daemon. 369 */ 370 if ((maxbdrun = nswbuf / 4) < 4) 371 maxbdrun = 4; 372 373 bogus_offset = kmem_alloc_pageable(kernel_map, PAGE_SIZE); 374 bogus_page = vm_page_alloc(kernel_object, 375 ((bogus_offset - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 376 VM_ALLOC_NORMAL); 377 cnt.v_wire_count++; 378 379} 380 381/* 382 * bfreekva() - free the kva allocation for a buffer. 383 * 384 * Must be called at splbio() or higher as this is the only locking for 385 * buffer_map. 386 * 387 * Since this call frees up buffer space, we call bufspacewakeup(). 388 */ 389static void 390bfreekva(struct buf * bp) 391{ 392 if (bp->b_kvasize) { 393 ++buffreekvacnt; 394 bufspace -= bp->b_kvasize; 395 vm_map_delete(buffer_map, 396 (vm_offset_t) bp->b_kvabase, 397 (vm_offset_t) bp->b_kvabase + bp->b_kvasize 398 ); 399 bp->b_kvasize = 0; 400 bufspacewakeup(); 401 } 402} 403 404/* 405 * bremfree: 406 * 407 * Remove the buffer from the appropriate free list. 408 */ 409void 410bremfree(struct buf * bp) 411{ 412 int s = splbio(); 413 int old_qindex = bp->b_qindex; 414 415 if (bp->b_qindex != QUEUE_NONE) { 416 KASSERT(BUF_REFCNT(bp) == 1, ("bremfree: bp %p not locked",bp)); 417 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 418 bp->b_qindex = QUEUE_NONE; 419 runningbufspace += bp->b_bufsize; 420 } else { 421 if (BUF_REFCNT(bp) <= 1) 422 panic("bremfree: removing a buffer not on a queue"); 423 } 424 425 /* 426 * Fixup numfreebuffers count. If the buffer is invalid or not 427 * delayed-write, and it was on the EMPTY, LRU, or AGE queues, 428 * the buffer was free and we must decrement numfreebuffers. 429 */ 430 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { 431 switch(old_qindex) { 432 case QUEUE_DIRTY: 433 case QUEUE_CLEAN: 434 case QUEUE_EMPTY: 435 case QUEUE_EMPTYKVA: 436 --numfreebuffers; 437 break; 438 default: 439 break; 440 } 441 } 442 splx(s); 443} 444 445 446/* 447 * Get a buffer with the specified data. Look in the cache first. We 448 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 449 * is set, the buffer is valid and we do not have to do anything ( see 450 * getblk() ). 451 */ 452int 453bread(struct vnode * vp, daddr_t blkno, int size, struct ucred * cred, 454 struct buf ** bpp) 455{ 456 struct buf *bp; 457 458 bp = getblk(vp, blkno, size, 0, 0); 459 *bpp = bp; 460 461 /* if not found in cache, do some I/O */ 462 if ((bp->b_flags & B_CACHE) == 0) { 463 if (curproc != NULL) 464 curproc->p_stats->p_ru.ru_inblock++; 465 KASSERT(!(bp->b_flags & B_ASYNC), ("bread: illegal async bp %p", bp)); 466 bp->b_iocmd = BIO_READ; 467 bp->b_flags &= ~B_INVAL; 468 bp->b_ioflags &= ~BIO_ERROR; 469 if (bp->b_rcred == NOCRED) { 470 if (cred != NOCRED) 471 crhold(cred); 472 bp->b_rcred = cred; 473 } 474 vfs_busy_pages(bp, 0); 475 VOP_STRATEGY(vp, bp); 476 return (bufwait(bp)); 477 } 478 return (0); 479} 480 481/* 482 * Operates like bread, but also starts asynchronous I/O on 483 * read-ahead blocks. We must clear BIO_ERROR and B_INVAL prior 484 * to initiating I/O . If B_CACHE is set, the buffer is valid 485 * and we do not have to do anything. 486 */ 487int 488breadn(struct vnode * vp, daddr_t blkno, int size, 489 daddr_t * rablkno, int *rabsize, 490 int cnt, struct ucred * cred, struct buf ** bpp) 491{ 492 struct buf *bp, *rabp; 493 int i; 494 int rv = 0, readwait = 0; 495 496 *bpp = bp = getblk(vp, blkno, size, 0, 0); 497 498 /* if not found in cache, do some I/O */ 499 if ((bp->b_flags & B_CACHE) == 0) { 500 if (curproc != NULL) 501 curproc->p_stats->p_ru.ru_inblock++; 502 bp->b_iocmd = BIO_READ; 503 bp->b_flags &= ~B_INVAL; 504 bp->b_ioflags &= ~BIO_ERROR; 505 if (bp->b_rcred == NOCRED) { 506 if (cred != NOCRED) 507 crhold(cred); 508 bp->b_rcred = cred; 509 } 510 vfs_busy_pages(bp, 0); 511 VOP_STRATEGY(vp, bp); 512 ++readwait; 513 } 514 515 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 516 if (inmem(vp, *rablkno)) 517 continue; 518 rabp = getblk(vp, *rablkno, *rabsize, 0, 0); 519 520 if ((rabp->b_flags & B_CACHE) == 0) { 521 if (curproc != NULL) 522 curproc->p_stats->p_ru.ru_inblock++; 523 rabp->b_flags |= B_ASYNC; 524 rabp->b_flags &= ~B_INVAL; 525 rabp->b_ioflags &= ~BIO_ERROR; 526 rabp->b_iocmd = BIO_READ; 527 if (rabp->b_rcred == NOCRED) { 528 if (cred != NOCRED) 529 crhold(cred); 530 rabp->b_rcred = cred; 531 } 532 vfs_busy_pages(rabp, 0); 533 BUF_KERNPROC(rabp); 534 VOP_STRATEGY(vp, rabp); 535 } else { 536 brelse(rabp); 537 } 538 } 539 540 if (readwait) { 541 rv = bufwait(bp); 542 } 543 return (rv); 544} 545 546/* 547 * Write, release buffer on completion. (Done by iodone 548 * if async). Do not bother writing anything if the buffer 549 * is invalid. 550 * 551 * Note that we set B_CACHE here, indicating that buffer is 552 * fully valid and thus cacheable. This is true even of NFS 553 * now so we set it generally. This could be set either here 554 * or in biodone() since the I/O is synchronous. We put it 555 * here. 556 */ 557int 558bwrite(struct buf * bp) 559{ 560 int oldflags, s; 561 struct buf *newbp; 562 563 if (bp->b_flags & B_INVAL) { 564 brelse(bp); 565 return (0); 566 } 567 568 oldflags = bp->b_flags; 569 570 if (BUF_REFCNT(bp) == 0) 571 panic("bwrite: buffer is not busy???"); 572 s = splbio(); 573 /* 574 * If a background write is already in progress, delay 575 * writing this block if it is asynchronous. Otherwise 576 * wait for the background write to complete. 577 */ 578 if (bp->b_xflags & BX_BKGRDINPROG) { 579 if (bp->b_flags & B_ASYNC) { 580 splx(s); 581 bdwrite(bp); 582 return (0); 583 } 584 bp->b_xflags |= BX_BKGRDWAIT; 585 tsleep(&bp->b_xflags, PRIBIO, "biord", 0); 586 if (bp->b_xflags & BX_BKGRDINPROG) 587 panic("bwrite: still writing"); 588 } 589 590 /* Mark the buffer clean */ 591 bundirty(bp); 592 593 /* 594 * If this buffer is marked for background writing and we 595 * do not have to wait for it, make a copy and write the 596 * copy so as to leave this buffer ready for further use. 597 */ 598 if ((bp->b_xflags & BX_BKGRDWRITE) && (bp->b_flags & B_ASYNC)) { 599 if (bp->b_iodone != NULL) { 600 printf("bp->b_iodone = %p\n", bp->b_iodone); 601 panic("bwrite: need chained iodone"); 602 } 603 604 /* get a new block */ 605 newbp = geteblk(bp->b_bufsize); 606 607 /* set it to be identical to the old block */ 608 memcpy(newbp->b_data, bp->b_data, bp->b_bufsize); 609 bgetvp(bp->b_vp, newbp); 610 newbp->b_lblkno = bp->b_lblkno; 611 newbp->b_blkno = bp->b_blkno; 612 newbp->b_offset = bp->b_offset; 613 newbp->b_iodone = vfs_backgroundwritedone; 614 newbp->b_flags |= B_ASYNC; 615 newbp->b_flags &= ~B_INVAL; 616 617 /* move over the dependencies */ 618 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_movedeps) 619 (*bioops.io_movedeps)(bp, newbp); 620 621 /* 622 * Initiate write on the copy, release the original to 623 * the B_LOCKED queue so that it cannot go away until 624 * the background write completes. If not locked it could go 625 * away and then be reconstituted while it was being written. 626 * If the reconstituted buffer were written, we could end up 627 * with two background copies being written at the same time. 628 */ 629 bp->b_xflags |= BX_BKGRDINPROG; 630 bp->b_flags |= B_LOCKED; 631 bqrelse(bp); 632 bp = newbp; 633 } 634 635 bp->b_flags &= ~B_DONE; 636 bp->b_ioflags &= ~BIO_ERROR; 637 bp->b_flags |= B_WRITEINPROG | B_CACHE; 638 bp->b_iocmd = BIO_WRITE; 639 640 bp->b_vp->v_numoutput++; 641 vfs_busy_pages(bp, 1); 642 if (curproc != NULL) 643 curproc->p_stats->p_ru.ru_oublock++; 644 splx(s); 645 if (oldflags & B_ASYNC) 646 BUF_KERNPROC(bp); 647 BUF_STRATEGY(bp); 648 649 if ((oldflags & B_ASYNC) == 0) { 650 int rtval = bufwait(bp); 651 brelse(bp); 652 return (rtval); 653 } 654 655 return (0); 656} 657 658/* 659 * Complete a background write started from bwrite. 660 */ 661static void 662vfs_backgroundwritedone(bp) 663 struct buf *bp; 664{ 665 struct buf *origbp; 666 667 /* 668 * Find the original buffer that we are writing. 669 */ 670 if ((origbp = gbincore(bp->b_vp, bp->b_lblkno)) == NULL) 671 panic("backgroundwritedone: lost buffer"); 672 /* 673 * Process dependencies then return any unfinished ones. 674 */ 675 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_complete) 676 (*bioops.io_complete)(bp); 677 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_movedeps) 678 (*bioops.io_movedeps)(bp, origbp); 679 /* 680 * Clear the BX_BKGRDINPROG flag in the original buffer 681 * and awaken it if it is waiting for the write to complete. 682 */ 683 origbp->b_xflags &= ~BX_BKGRDINPROG; 684 if (origbp->b_xflags & BX_BKGRDWAIT) { 685 origbp->b_xflags &= ~BX_BKGRDWAIT; 686 wakeup(&origbp->b_xflags); 687 } 688 /* 689 * Clear the B_LOCKED flag and remove it from the locked 690 * queue if it currently resides there. 691 */ 692 origbp->b_flags &= ~B_LOCKED; 693 if (BUF_LOCK(origbp, LK_EXCLUSIVE | LK_NOWAIT) == 0) { 694 bremfree(origbp); 695 bqrelse(origbp); 696 } 697 /* 698 * This buffer is marked B_NOCACHE, so when it is released 699 * by biodone, it will be tossed. We mark it with BIO_READ 700 * to avoid biodone doing a second vwakeup. 701 */ 702 bp->b_flags |= B_NOCACHE; 703 bp->b_iocmd = BIO_READ; 704 bp->b_flags &= ~(B_CACHE | B_DONE); 705 bp->b_iodone = 0; 706 bufdone(bp); 707} 708 709/* 710 * Delayed write. (Buffer is marked dirty). Do not bother writing 711 * anything if the buffer is marked invalid. 712 * 713 * Note that since the buffer must be completely valid, we can safely 714 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 715 * biodone() in order to prevent getblk from writing the buffer 716 * out synchronously. 717 */ 718void 719bdwrite(struct buf * bp) 720{ 721 if (BUF_REFCNT(bp) == 0) 722 panic("bdwrite: buffer is not busy"); 723 724 if (bp->b_flags & B_INVAL) { 725 brelse(bp); 726 return; 727 } 728 bdirty(bp); 729 730 /* 731 * Set B_CACHE, indicating that the buffer is fully valid. This is 732 * true even of NFS now. 733 */ 734 bp->b_flags |= B_CACHE; 735 736 /* 737 * This bmap keeps the system from needing to do the bmap later, 738 * perhaps when the system is attempting to do a sync. Since it 739 * is likely that the indirect block -- or whatever other datastructure 740 * that the filesystem needs is still in memory now, it is a good 741 * thing to do this. Note also, that if the pageout daemon is 742 * requesting a sync -- there might not be enough memory to do 743 * the bmap then... So, this is important to do. 744 */ 745 if (bp->b_lblkno == bp->b_blkno) { 746 VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 747 } 748 749 /* 750 * Set the *dirty* buffer range based upon the VM system dirty pages. 751 */ 752 vfs_setdirty(bp); 753 754 /* 755 * We need to do this here to satisfy the vnode_pager and the 756 * pageout daemon, so that it thinks that the pages have been 757 * "cleaned". Note that since the pages are in a delayed write 758 * buffer -- the VFS layer "will" see that the pages get written 759 * out on the next sync, or perhaps the cluster will be completed. 760 */ 761 vfs_clean_pages(bp); 762 bqrelse(bp); 763 764 /* 765 * Wakeup the buffer flushing daemon if we have saturated the 766 * buffer cache. 767 */ 768 769 bd_wakeup(hidirtybuffers); 770 771 /* 772 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 773 * due to the softdep code. 774 */ 775} 776 777/* 778 * bdirty: 779 * 780 * Turn buffer into delayed write request. We must clear BIO_READ and 781 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 782 * itself to properly update it in the dirty/clean lists. We mark it 783 * B_DONE to ensure that any asynchronization of the buffer properly 784 * clears B_DONE ( else a panic will occur later ). 785 * 786 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 787 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 788 * should only be called if the buffer is known-good. 789 * 790 * Since the buffer is not on a queue, we do not update the numfreebuffers 791 * count. 792 * 793 * Must be called at splbio(). 794 * The buffer must be on QUEUE_NONE. 795 */ 796void 797bdirty(bp) 798 struct buf *bp; 799{ 800 KASSERT(bp->b_qindex == QUEUE_NONE, ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 801 bp->b_flags &= ~(B_RELBUF); 802 bp->b_iocmd = BIO_WRITE; 803 804 if ((bp->b_flags & B_DELWRI) == 0) { 805 bp->b_flags |= B_DONE | B_DELWRI; 806 reassignbuf(bp, bp->b_vp); 807 ++numdirtybuffers; 808 bd_wakeup(hidirtybuffers); 809 } 810} 811 812/* 813 * bundirty: 814 * 815 * Clear B_DELWRI for buffer. 816 * 817 * Since the buffer is not on a queue, we do not update the numfreebuffers 818 * count. 819 * 820 * Must be called at splbio(). 821 * The buffer must be on QUEUE_NONE. 822 */ 823 824void 825bundirty(bp) 826 struct buf *bp; 827{ 828 KASSERT(bp->b_qindex == QUEUE_NONE, ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 829 830 if (bp->b_flags & B_DELWRI) { 831 bp->b_flags &= ~B_DELWRI; 832 reassignbuf(bp, bp->b_vp); 833 --numdirtybuffers; 834 numdirtywakeup(); 835 } 836 /* 837 * Since it is now being written, we can clear its deferred write flag. 838 */ 839 bp->b_flags &= ~B_DEFERRED; 840} 841 842/* 843 * bawrite: 844 * 845 * Asynchronous write. Start output on a buffer, but do not wait for 846 * it to complete. The buffer is released when the output completes. 847 * 848 * bwrite() ( or the VOP routine anyway ) is responsible for handling 849 * B_INVAL buffers. Not us. 850 */ 851void 852bawrite(struct buf * bp) 853{ 854 bp->b_flags |= B_ASYNC; 855 (void) BUF_WRITE(bp); 856} 857 858/* 859 * bowrite: 860 * 861 * Ordered write. Start output on a buffer, and flag it so that the 862 * device will write it in the order it was queued. The buffer is 863 * released when the output completes. bwrite() ( or the VOP routine 864 * anyway ) is responsible for handling B_INVAL buffers. 865 */ 866int 867bowrite(struct buf * bp) 868{ 869 bp->b_ioflags |= BIO_ORDERED; 870 bp->b_flags |= B_ASYNC; 871 return (BUF_WRITE(bp)); 872} 873 874/* 875 * bwillwrite: 876 * 877 * Called prior to the locking of any vnodes when we are expecting to 878 * write. We do not want to starve the buffer cache with too many 879 * dirty buffers so we block here. By blocking prior to the locking 880 * of any vnodes we attempt to avoid the situation where a locked vnode 881 * prevents the various system daemons from flushing related buffers. 882 */ 883 884void 885bwillwrite(void) 886{ 887 int slop = hidirtybuffers / 10; 888 889 if (numdirtybuffers > hidirtybuffers + slop) { 890 int s; 891 892 s = splbio(); 893 while (numdirtybuffers > hidirtybuffers) { 894 bd_wakeup(hidirtybuffers); 895 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH; 896 tsleep(&needsbuffer, (PRIBIO + 4), "flswai", 0); 897 } 898 splx(s); 899 } 900} 901 902/* 903 * brelse: 904 * 905 * Release a busy buffer and, if requested, free its resources. The 906 * buffer will be stashed in the appropriate bufqueue[] allowing it 907 * to be accessed later as a cache entity or reused for other purposes. 908 */ 909void 910brelse(struct buf * bp) 911{ 912 int s; 913 914 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 915 916 s = splbio(); 917 918 if (bp->b_flags & B_LOCKED) 919 bp->b_ioflags &= ~BIO_ERROR; 920 921 if (bp->b_iocmd == BIO_WRITE && 922 (bp->b_ioflags & BIO_ERROR) && 923 !(bp->b_flags & B_INVAL)) { 924 /* 925 * Failed write, redirty. Must clear BIO_ERROR to prevent 926 * pages from being scrapped. If B_INVAL is set then 927 * this case is not run and the next case is run to 928 * destroy the buffer. B_INVAL can occur if the buffer 929 * is outside the range supported by the underlying device. 930 */ 931 bp->b_ioflags &= ~BIO_ERROR; 932 bdirty(bp); 933 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 934 (bp->b_ioflags & BIO_ERROR) || 935 bp->b_iocmd == BIO_DELETE || (bp->b_bufsize <= 0)) { 936 /* 937 * Either a failed I/O or we were asked to free or not 938 * cache the buffer. 939 */ 940 bp->b_flags |= B_INVAL; 941 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_deallocate) 942 (*bioops.io_deallocate)(bp); 943 if (bp->b_flags & B_DELWRI) { 944 --numdirtybuffers; 945 numdirtywakeup(); 946 } 947 bp->b_flags &= ~(B_DELWRI | B_CACHE); 948 if ((bp->b_flags & B_VMIO) == 0) { 949 if (bp->b_bufsize) 950 allocbuf(bp, 0); 951 if (bp->b_vp) 952 brelvp(bp); 953 } 954 } 955 956 /* 957 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 958 * is called with B_DELWRI set, the underlying pages may wind up 959 * getting freed causing a previous write (bdwrite()) to get 'lost' 960 * because pages associated with a B_DELWRI bp are marked clean. 961 * 962 * We still allow the B_INVAL case to call vfs_vmio_release(), even 963 * if B_DELWRI is set. 964 */ 965 966 if (bp->b_flags & B_DELWRI) 967 bp->b_flags &= ~B_RELBUF; 968 969 /* 970 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 971 * constituted, not even NFS buffers now. Two flags effect this. If 972 * B_INVAL, the struct buf is invalidated but the VM object is kept 973 * around ( i.e. so it is trivial to reconstitute the buffer later ). 974 * 975 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 976 * invalidated. BIO_ERROR cannot be set for a failed write unless the 977 * buffer is also B_INVAL because it hits the re-dirtying code above. 978 * 979 * Normally we can do this whether a buffer is B_DELWRI or not. If 980 * the buffer is an NFS buffer, it is tracking piecemeal writes or 981 * the commit state and we cannot afford to lose the buffer. If the 982 * buffer has a background write in progress, we need to keep it 983 * around to prevent it from being reconstituted and starting a second 984 * background write. 985 */ 986 if ((bp->b_flags & B_VMIO) 987 && !(bp->b_vp->v_tag == VT_NFS && 988 !vn_isdisk(bp->b_vp, NULL) && 989 (bp->b_flags & B_DELWRI) && 990 (bp->b_xflags & BX_BKGRDINPROG)) 991 ) { 992 993 int i, j, resid; 994 vm_page_t m; 995 off_t foff; 996 vm_pindex_t poff; 997 vm_object_t obj; 998 struct vnode *vp; 999 1000 vp = bp->b_vp; 1001 1002 /* 1003 * Get the base offset and length of the buffer. Note that 1004 * for block sizes that are less then PAGE_SIZE, the b_data 1005 * base of the buffer does not represent exactly b_offset and 1006 * neither b_offset nor b_size are necessarily page aligned. 1007 * Instead, the starting position of b_offset is: 1008 * 1009 * b_data + (b_offset & PAGE_MASK) 1010 * 1011 * block sizes less then DEV_BSIZE (usually 512) are not 1012 * supported due to the page granularity bits (m->valid, 1013 * m->dirty, etc...). 1014 * 1015 * See man buf(9) for more information 1016 */ 1017 1018 resid = bp->b_bufsize; 1019 foff = bp->b_offset; 1020 1021 for (i = 0; i < bp->b_npages; i++) { 1022 m = bp->b_pages[i]; 1023 vm_page_flag_clear(m, PG_ZERO); 1024 if (m == bogus_page) { 1025 1026 obj = (vm_object_t) vp->v_object; 1027 poff = OFF_TO_IDX(bp->b_offset); 1028 1029 for (j = i; j < bp->b_npages; j++) { 1030 m = bp->b_pages[j]; 1031 if (m == bogus_page) { 1032 m = vm_page_lookup(obj, poff + j); 1033 if (!m) { 1034 panic("brelse: page missing\n"); 1035 } 1036 bp->b_pages[j] = m; 1037 } 1038 } 1039 1040 if ((bp->b_flags & B_INVAL) == 0) { 1041 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 1042 } 1043 } 1044 if ((bp->b_flags & B_NOCACHE) || (bp->b_ioflags & BIO_ERROR)) { 1045 int poffset = foff & PAGE_MASK; 1046 int presid = resid > (PAGE_SIZE - poffset) ? 1047 (PAGE_SIZE - poffset) : resid; 1048 1049 KASSERT(presid >= 0, ("brelse: extra page")); 1050 vm_page_set_invalid(m, poffset, presid); 1051 } 1052 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1053 foff = (foff + PAGE_SIZE) & ~PAGE_MASK; 1054 } 1055 1056 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1057 vfs_vmio_release(bp); 1058 1059 } else if (bp->b_flags & B_VMIO) { 1060 1061 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1062 vfs_vmio_release(bp); 1063 1064 } 1065 1066 if (bp->b_qindex != QUEUE_NONE) 1067 panic("brelse: free buffer onto another queue???"); 1068 if (BUF_REFCNT(bp) > 1) { 1069 /* Temporary panic to verify exclusive locking */ 1070 /* This panic goes away when we allow shared refs */ 1071 panic("brelse: multiple refs"); 1072 /* do not release to free list */ 1073 BUF_UNLOCK(bp); 1074 splx(s); 1075 return; 1076 } 1077 1078 /* enqueue */ 1079 1080 /* buffers with no memory */ 1081 if (bp->b_bufsize == 0) { 1082 bp->b_flags |= B_INVAL; 1083 bp->b_xflags &= ~BX_BKGRDWRITE; 1084 if (bp->b_xflags & BX_BKGRDINPROG) 1085 panic("losing buffer 1"); 1086 if (bp->b_kvasize) { 1087 bp->b_qindex = QUEUE_EMPTYKVA; 1088 } else { 1089 bp->b_qindex = QUEUE_EMPTY; 1090 } 1091 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1092 LIST_REMOVE(bp, b_hash); 1093 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1094 bp->b_dev = NODEV; 1095 /* buffers with junk contents */ 1096 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || (bp->b_ioflags & BIO_ERROR)) { 1097 bp->b_flags |= B_INVAL; 1098 bp->b_xflags &= ~BX_BKGRDWRITE; 1099 if (bp->b_xflags & BX_BKGRDINPROG) 1100 panic("losing buffer 2"); 1101 bp->b_qindex = QUEUE_CLEAN; 1102 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1103 LIST_REMOVE(bp, b_hash); 1104 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1105 bp->b_dev = NODEV; 1106 1107 /* buffers that are locked */ 1108 } else if (bp->b_flags & B_LOCKED) { 1109 bp->b_qindex = QUEUE_LOCKED; 1110 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LOCKED], bp, b_freelist); 1111 1112 /* remaining buffers */ 1113 } else { 1114 switch(bp->b_flags & (B_DELWRI|B_AGE)) { 1115 case B_DELWRI | B_AGE: 1116 bp->b_qindex = QUEUE_DIRTY; 1117 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_DIRTY], bp, b_freelist); 1118 break; 1119 case B_DELWRI: 1120 bp->b_qindex = QUEUE_DIRTY; 1121 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist); 1122 break; 1123 case B_AGE: 1124 bp->b_qindex = QUEUE_CLEAN; 1125 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1126 break; 1127 default: 1128 bp->b_qindex = QUEUE_CLEAN; 1129 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1130 break; 1131 } 1132 } 1133 1134 /* 1135 * If B_INVAL, clear B_DELWRI. We've already placed the buffer 1136 * on the correct queue. 1137 */ 1138 if ((bp->b_flags & (B_INVAL|B_DELWRI)) == (B_INVAL|B_DELWRI)) { 1139 bp->b_flags &= ~B_DELWRI; 1140 --numdirtybuffers; 1141 numdirtywakeup(); 1142 } 1143 1144 runningbufspace -= bp->b_bufsize; 1145 1146 /* 1147 * Fixup numfreebuffers count. The bp is on an appropriate queue 1148 * unless locked. We then bump numfreebuffers if it is not B_DELWRI. 1149 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1150 * if B_INVAL is set ). 1151 */ 1152 1153 if ((bp->b_flags & B_LOCKED) == 0 && !(bp->b_flags & B_DELWRI)) 1154 bufcountwakeup(); 1155 1156 /* 1157 * Something we can maybe free. 1158 */ 1159 1160 if (bp->b_bufsize || bp->b_kvasize) 1161 bufspacewakeup(); 1162 1163 /* unlock */ 1164 BUF_UNLOCK(bp); 1165 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1166 bp->b_ioflags &= ~BIO_ORDERED; 1167 splx(s); 1168} 1169 1170/* 1171 * Release a buffer back to the appropriate queue but do not try to free 1172 * it. 1173 * 1174 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1175 * biodone() to requeue an async I/O on completion. It is also used when 1176 * known good buffers need to be requeued but we think we may need the data 1177 * again soon. 1178 */ 1179void 1180bqrelse(struct buf * bp) 1181{ 1182 int s; 1183 1184 s = splbio(); 1185 1186 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1187 1188 if (bp->b_qindex != QUEUE_NONE) 1189 panic("bqrelse: free buffer onto another queue???"); 1190 if (BUF_REFCNT(bp) > 1) { 1191 /* do not release to free list */ 1192 panic("bqrelse: multiple refs"); 1193 BUF_UNLOCK(bp); 1194 splx(s); 1195 return; 1196 } 1197 if (bp->b_flags & B_LOCKED) { 1198 bp->b_ioflags &= ~BIO_ERROR; 1199 bp->b_qindex = QUEUE_LOCKED; 1200 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LOCKED], bp, b_freelist); 1201 /* buffers with stale but valid contents */ 1202 } else if (bp->b_flags & B_DELWRI) { 1203 bp->b_qindex = QUEUE_DIRTY; 1204 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist); 1205 } else { 1206 bp->b_qindex = QUEUE_CLEAN; 1207 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1208 } 1209 1210 runningbufspace -= bp->b_bufsize; 1211 1212 if ((bp->b_flags & B_LOCKED) == 0 && 1213 ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI))) { 1214 bufcountwakeup(); 1215 } 1216 1217 /* 1218 * Something we can maybe wakeup 1219 */ 1220 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1221 bufspacewakeup(); 1222 1223 /* unlock */ 1224 BUF_UNLOCK(bp); 1225 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1226 bp->b_ioflags &= ~BIO_ORDERED; 1227 splx(s); 1228} 1229 1230static void 1231vfs_vmio_release(bp) 1232 struct buf *bp; 1233{ 1234 int i, s; 1235 vm_page_t m; 1236 1237 s = splvm(); 1238 for (i = 0; i < bp->b_npages; i++) { 1239 m = bp->b_pages[i]; 1240 bp->b_pages[i] = NULL; 1241 /* 1242 * In order to keep page LRU ordering consistent, put 1243 * everything on the inactive queue. 1244 */ 1245 vm_page_unwire(m, 0); 1246 /* 1247 * We don't mess with busy pages, it is 1248 * the responsibility of the process that 1249 * busied the pages to deal with them. 1250 */ 1251 if ((m->flags & PG_BUSY) || (m->busy != 0)) 1252 continue; 1253 1254 if (m->wire_count == 0) { 1255 vm_page_flag_clear(m, PG_ZERO); 1256 /* 1257 * Might as well free the page if we can and it has 1258 * no valid data. 1259 */ 1260 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && m->hold_count == 0) { 1261 vm_page_busy(m); 1262 vm_page_protect(m, VM_PROT_NONE); 1263 vm_page_free(m); 1264 } 1265 } 1266 } 1267 runningbufspace -= bp->b_bufsize; 1268 splx(s); 1269 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages); 1270 if (bp->b_bufsize) 1271 bufspacewakeup(); 1272 bp->b_npages = 0; 1273 bp->b_bufsize = 0; 1274 bp->b_flags &= ~B_VMIO; 1275 if (bp->b_vp) 1276 brelvp(bp); 1277} 1278 1279/* 1280 * Check to see if a block is currently memory resident. 1281 */ 1282struct buf * 1283gbincore(struct vnode * vp, daddr_t blkno) 1284{ 1285 struct buf *bp; 1286 struct bufhashhdr *bh; 1287 1288 bh = bufhash(vp, blkno); 1289 1290 /* Search hash chain */ 1291 LIST_FOREACH(bp, bh, b_hash) { 1292 /* hit */ 1293 if (bp->b_vp == vp && bp->b_lblkno == blkno && 1294 (bp->b_flags & B_INVAL) == 0) { 1295 break; 1296 } 1297 } 1298 return (bp); 1299} 1300 1301/* 1302 * vfs_bio_awrite: 1303 * 1304 * Implement clustered async writes for clearing out B_DELWRI buffers. 1305 * This is much better then the old way of writing only one buffer at 1306 * a time. Note that we may not be presented with the buffers in the 1307 * correct order, so we search for the cluster in both directions. 1308 */ 1309int 1310vfs_bio_awrite(struct buf * bp) 1311{ 1312 int i; 1313 int j; 1314 daddr_t lblkno = bp->b_lblkno; 1315 struct vnode *vp = bp->b_vp; 1316 int s; 1317 int ncl; 1318 struct buf *bpa; 1319 int nwritten; 1320 int size; 1321 int maxcl; 1322 1323 s = splbio(); 1324 /* 1325 * right now we support clustered writing only to regular files. If 1326 * we find a clusterable block we could be in the middle of a cluster 1327 * rather then at the beginning. 1328 */ 1329 if ((vp->v_type == VREG) && 1330 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1331 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1332 1333 size = vp->v_mount->mnt_stat.f_iosize; 1334 maxcl = MAXPHYS / size; 1335 1336 for (i = 1; i < maxcl; i++) { 1337 if ((bpa = gbincore(vp, lblkno + i)) && 1338 BUF_REFCNT(bpa) == 0 && 1339 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == 1340 (B_DELWRI | B_CLUSTEROK)) && 1341 (bpa->b_bufsize == size)) { 1342 if ((bpa->b_blkno == bpa->b_lblkno) || 1343 (bpa->b_blkno != 1344 bp->b_blkno + ((i * size) >> DEV_BSHIFT))) 1345 break; 1346 } else { 1347 break; 1348 } 1349 } 1350 for (j = 1; i + j <= maxcl && j <= lblkno; j++) { 1351 if ((bpa = gbincore(vp, lblkno - j)) && 1352 BUF_REFCNT(bpa) == 0 && 1353 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == 1354 (B_DELWRI | B_CLUSTEROK)) && 1355 (bpa->b_bufsize == size)) { 1356 if ((bpa->b_blkno == bpa->b_lblkno) || 1357 (bpa->b_blkno != 1358 bp->b_blkno - ((j * size) >> DEV_BSHIFT))) 1359 break; 1360 } else { 1361 break; 1362 } 1363 } 1364 --j; 1365 ncl = i + j; 1366 /* 1367 * this is a possible cluster write 1368 */ 1369 if (ncl != 1) { 1370 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl); 1371 splx(s); 1372 return nwritten; 1373 } 1374 } 1375 1376 BUF_LOCK(bp, LK_EXCLUSIVE); 1377 bremfree(bp); 1378 bp->b_flags |= B_ASYNC; 1379 1380 splx(s); 1381 /* 1382 * default (old) behavior, writing out only one block 1383 * 1384 * XXX returns b_bufsize instead of b_bcount for nwritten? 1385 */ 1386 nwritten = bp->b_bufsize; 1387 (void) BUF_WRITE(bp); 1388 1389 return nwritten; 1390} 1391 1392/* 1393 * getnewbuf: 1394 * 1395 * Find and initialize a new buffer header, freeing up existing buffers 1396 * in the bufqueues as necessary. The new buffer is returned locked. 1397 * 1398 * Important: B_INVAL is not set. If the caller wishes to throw the 1399 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1400 * 1401 * We block if: 1402 * We have insufficient buffer headers 1403 * We have insufficient buffer space 1404 * buffer_map is too fragmented ( space reservation fails ) 1405 * If we have to flush dirty buffers ( but we try to avoid this ) 1406 * 1407 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1408 * Instead we ask the buf daemon to do it for us. We attempt to 1409 * avoid piecemeal wakeups of the pageout daemon. 1410 */ 1411 1412static struct buf * 1413getnewbuf(int slpflag, int slptimeo, int size, int maxsize) 1414{ 1415 struct buf *bp; 1416 struct buf *nbp; 1417 int defrag = 0; 1418 int nqindex; 1419 int isspecial; 1420 static int flushingbufs; 1421 1422 if (curproc && (curproc->p_flag & P_BUFEXHAUST) == 0) 1423 isspecial = 0; 1424 else 1425 isspecial = 1; 1426 1427 ++getnewbufcalls; 1428 --getnewbufrestarts; 1429restart: 1430 ++getnewbufrestarts; 1431 1432 /* 1433 * Setup for scan. If we do not have enough free buffers, 1434 * we setup a degenerate case that immediately fails. Note 1435 * that if we are specially marked process, we are allowed to 1436 * dip into our reserves. 1437 * 1438 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 1439 * 1440 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 1441 * However, there are a number of cases (defragging, reusing, ...) 1442 * where we cannot backup. 1443 */ 1444 1445 if (isspecial == 0 && numfreebuffers < lofreebuffers) { 1446 /* 1447 * This will cause an immediate failure 1448 */ 1449 nqindex = QUEUE_CLEAN; 1450 nbp = NULL; 1451 } else { 1452 /* 1453 * Locate a buffer which already has KVA assigned. First 1454 * try EMPTYKVA buffers. 1455 */ 1456 nqindex = QUEUE_EMPTYKVA; 1457 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 1458 1459 if (nbp == NULL) { 1460 /* 1461 * If no EMPTYKVA buffers and we are either 1462 * defragging or reusing, locate a CLEAN buffer 1463 * to free or reuse. If bufspace useage is low 1464 * skip this step so we can allocate a new buffer. 1465 */ 1466 if (defrag || bufspace >= lobufspace) { 1467 nqindex = QUEUE_CLEAN; 1468 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 1469 } 1470 1471 /* 1472 * Nada. If we are allowed to allocate an EMPTY 1473 * buffer, go get one. 1474 */ 1475 if (nbp == NULL && defrag == 0 && 1476 (isspecial || bufspace < hibufspace)) { 1477 nqindex = QUEUE_EMPTY; 1478 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1479 } 1480 } 1481 } 1482 1483 /* 1484 * Run scan, possibly freeing data and/or kva mappings on the fly 1485 * depending. 1486 */ 1487 1488 while ((bp = nbp) != NULL) { 1489 int qindex = nqindex; 1490 1491 /* 1492 * Calculate next bp ( we can only use it if we do not block 1493 * or do other fancy things ). 1494 */ 1495 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 1496 switch(qindex) { 1497 case QUEUE_EMPTY: 1498 nqindex = QUEUE_EMPTYKVA; 1499 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]))) 1500 break; 1501 /* fall through */ 1502 case QUEUE_EMPTYKVA: 1503 nqindex = QUEUE_CLEAN; 1504 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]))) 1505 break; 1506 /* fall through */ 1507 case QUEUE_CLEAN: 1508 /* 1509 * nbp is NULL. 1510 */ 1511 break; 1512 } 1513 } 1514 1515 /* 1516 * Sanity Checks 1517 */ 1518 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp)); 1519 1520 /* 1521 * Note: we no longer distinguish between VMIO and non-VMIO 1522 * buffers. 1523 */ 1524 1525 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); 1526 1527 /* 1528 * If we are defragging then we need a buffer with 1529 * b_kvasize != 0. XXX this situation should no longer 1530 * occur, if defrag is non-zero the buffer's b_kvasize 1531 * should also be non-zero at this point. XXX 1532 */ 1533 if (defrag && bp->b_kvasize == 0) { 1534 printf("Warning: defrag empty buffer %p\n", bp); 1535 continue; 1536 } 1537 1538 /* 1539 * Start freeing the bp. This is somewhat involved. nbp 1540 * remains valid only for QUEUE_EMPTY[KVA] bp's. 1541 */ 1542 1543 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) 1544 panic("getnewbuf: locked buf"); 1545 bremfree(bp); 1546 1547 if (qindex == QUEUE_CLEAN) { 1548 if (bp->b_flags & B_VMIO) { 1549 bp->b_flags &= ~B_ASYNC; 1550 vfs_vmio_release(bp); 1551 } 1552 if (bp->b_vp) 1553 brelvp(bp); 1554 } 1555 1556 /* 1557 * NOTE: nbp is now entirely invalid. We can only restart 1558 * the scan from this point on. 1559 * 1560 * Get the rest of the buffer freed up. b_kva* is still 1561 * valid after this operation. 1562 */ 1563 1564 if (bp->b_rcred != NOCRED) { 1565 crfree(bp->b_rcred); 1566 bp->b_rcred = NOCRED; 1567 } 1568 if (bp->b_wcred != NOCRED) { 1569 crfree(bp->b_wcred); 1570 bp->b_wcred = NOCRED; 1571 } 1572 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_deallocate) 1573 (*bioops.io_deallocate)(bp); 1574 if (bp->b_xflags & BX_BKGRDINPROG) 1575 panic("losing buffer 3"); 1576 LIST_REMOVE(bp, b_hash); 1577 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1578 1579 if (bp->b_bufsize) 1580 allocbuf(bp, 0); 1581 1582 bp->b_flags = 0; 1583 bp->b_ioflags = 0; 1584 bp->b_xflags = 0; 1585 bp->b_dev = NODEV; 1586 bp->b_vp = NULL; 1587 bp->b_blkno = bp->b_lblkno = 0; 1588 bp->b_offset = NOOFFSET; 1589 bp->b_iodone = 0; 1590 bp->b_error = 0; 1591 bp->b_resid = 0; 1592 bp->b_bcount = 0; 1593 bp->b_npages = 0; 1594 bp->b_dirtyoff = bp->b_dirtyend = 0; 1595 1596 LIST_INIT(&bp->b_dep); 1597 1598 /* 1599 * If we are defragging then free the buffer. 1600 */ 1601 if (defrag) { 1602 bp->b_flags |= B_INVAL; 1603 bfreekva(bp); 1604 brelse(bp); 1605 defrag = 0; 1606 goto restart; 1607 } 1608 1609 /* 1610 * If we are a normal process then deal with bufspace 1611 * hysteresis. A normal process tries to keep bufspace 1612 * between lobufspace and hibufspace. Note: if we encounter 1613 * a buffer with b_kvasize == 0 then it means we started 1614 * our scan on the EMPTY list and should allocate a new 1615 * buffer. 1616 */ 1617 if (isspecial == 0) { 1618 if (bufspace > hibufspace) 1619 flushingbufs = 1; 1620 if (flushingbufs && bp->b_kvasize != 0) { 1621 bp->b_flags |= B_INVAL; 1622 bfreekva(bp); 1623 brelse(bp); 1624 goto restart; 1625 } 1626 if (bufspace < lobufspace) 1627 flushingbufs = 0; 1628 } 1629 break; 1630 } 1631 1632 /* 1633 * If we exhausted our list, sleep as appropriate. We may have to 1634 * wakeup various daemons and write out some dirty buffers. 1635 * 1636 * Generally we are sleeping due to insufficient buffer space. 1637 */ 1638 1639 if (bp == NULL) { 1640 int flags; 1641 char *waitmsg; 1642 1643 if (defrag) { 1644 flags = VFS_BIO_NEED_BUFSPACE; 1645 waitmsg = "nbufkv"; 1646 } else if (bufspace >= hibufspace) { 1647 waitmsg = "nbufbs"; 1648 flags = VFS_BIO_NEED_BUFSPACE; 1649 } else { 1650 waitmsg = "newbuf"; 1651 flags = VFS_BIO_NEED_ANY; 1652 } 1653 1654 bd_speedup(); /* heeeelp */ 1655 1656 needsbuffer |= flags; 1657 while (needsbuffer & flags) { 1658 if (tsleep(&needsbuffer, (PRIBIO + 4) | slpflag, 1659 waitmsg, slptimeo)) 1660 return (NULL); 1661 } 1662 } else { 1663 /* 1664 * We finally have a valid bp. We aren't quite out of the 1665 * woods, we still have to reserve kva space. In order 1666 * to keep fragmentation sane we only allocate kva in 1667 * BKVASIZE chunks. 1668 */ 1669 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 1670 1671 if (maxsize != bp->b_kvasize) { 1672 vm_offset_t addr = 0; 1673 1674 bfreekva(bp); 1675 1676 if (vm_map_findspace(buffer_map, 1677 vm_map_min(buffer_map), maxsize, &addr)) { 1678 /* 1679 * Uh oh. Buffer map is to fragmented. We 1680 * must defragment the map. 1681 */ 1682 ++bufdefragcnt; 1683 defrag = 1; 1684 bp->b_flags |= B_INVAL; 1685 brelse(bp); 1686 goto restart; 1687 } 1688 if (addr) { 1689 vm_map_insert(buffer_map, NULL, 0, 1690 addr, addr + maxsize, 1691 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT); 1692 1693 bp->b_kvabase = (caddr_t) addr; 1694 bp->b_kvasize = maxsize; 1695 bufspace += bp->b_kvasize; 1696 ++bufreusecnt; 1697 } 1698 } 1699 bp->b_data = bp->b_kvabase; 1700 } 1701 return(bp); 1702} 1703 1704/* 1705 * waitfreebuffers: 1706 * 1707 * Wait for sufficient free buffers. Only called from normal processes. 1708 */ 1709 1710static void 1711waitfreebuffers(int slpflag, int slptimeo) 1712{ 1713 while (numfreebuffers < hifreebuffers) { 1714 if (numfreebuffers >= hifreebuffers) 1715 break; 1716 needsbuffer |= VFS_BIO_NEED_FREE; 1717 if (tsleep(&needsbuffer, (PRIBIO + 4)|slpflag, "biofre", slptimeo)) 1718 break; 1719 } 1720} 1721 1722/* 1723 * buf_daemon: 1724 * 1725 * buffer flushing daemon. Buffers are normally flushed by the 1726 * update daemon but if it cannot keep up this process starts to 1727 * take the load in an attempt to prevent getnewbuf() from blocking. 1728 */ 1729 1730static struct proc *bufdaemonproc; 1731static int bd_interval; 1732static int bd_flushto; 1733static int bd_flushinc; 1734 1735static struct kproc_desc buf_kp = { 1736 "bufdaemon", 1737 buf_daemon, 1738 &bufdaemonproc 1739}; 1740SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp) 1741 1742static void 1743buf_daemon() 1744{ 1745 int s; 1746 1747 /* 1748 * This process needs to be suspended prior to shutdown sync. 1749 */ 1750 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc, bufdaemonproc, 1751 SHUTDOWN_PRI_LAST); 1752 1753 /* 1754 * This process is allowed to take the buffer cache to the limit 1755 */ 1756 curproc->p_flag |= P_BUFEXHAUST; 1757 s = splbio(); 1758 1759 bd_interval = 5 * hz; /* dynamically adjusted */ 1760 bd_flushto = hidirtybuffers; /* dynamically adjusted */ 1761 bd_flushinc = 1; 1762 1763 for (;;) { 1764 kproc_suspend_loop(bufdaemonproc); 1765 1766 bd_request = 0; 1767 1768 /* 1769 * Do the flush. Limit the number of buffers we flush in one 1770 * go. The failure condition occurs when processes are writing 1771 * buffers faster then we can dispose of them. In this case 1772 * we may be flushing so often that the previous set of flushes 1773 * have not had time to complete, causing us to run out of 1774 * physical buffers and block. 1775 */ 1776 { 1777 int runcount = maxbdrun; 1778 1779 while (numdirtybuffers > bd_flushto && runcount) { 1780 --runcount; 1781 if (flushbufqueues() == 0) 1782 break; 1783 } 1784 } 1785 1786 if (bd_request || 1787 tsleep(&bd_request, PVM, "psleep", bd_interval) == 0) { 1788 /* 1789 * Another request is pending or we were woken up 1790 * without timing out. Flush more. 1791 */ 1792 --bd_flushto; 1793 if (bd_flushto >= numdirtybuffers - 5) { 1794 bd_flushto = numdirtybuffers - 10; 1795 bd_flushinc = 1; 1796 } 1797 if (bd_flushto < 2) 1798 bd_flushto = 2; 1799 } else { 1800 /* 1801 * We slept and timed out, we can slow down. 1802 */ 1803 bd_flushto += bd_flushinc; 1804 if (bd_flushto > hidirtybuffers) 1805 bd_flushto = hidirtybuffers; 1806 ++bd_flushinc; 1807 if (bd_flushinc > hidirtybuffers / 20 + 1) 1808 bd_flushinc = hidirtybuffers / 20 + 1; 1809 } 1810 1811 /* 1812 * Set the interval on a linear scale based on hidirtybuffers 1813 * with a maximum frequency of 1/10 second. 1814 */ 1815 bd_interval = bd_flushto * 5 * hz / hidirtybuffers; 1816 if (bd_interval < hz / 10) 1817 bd_interval = hz / 10; 1818 } 1819} 1820 1821/* 1822 * flushbufqueues: 1823 * 1824 * Try to flush a buffer in the dirty queue. We must be careful to 1825 * free up B_INVAL buffers instead of write them, which NFS is 1826 * particularly sensitive to. 1827 */ 1828 1829static int 1830flushbufqueues(void) 1831{ 1832 struct buf *bp; 1833 int r = 0; 1834 1835 bp = TAILQ_FIRST(&bufqueues[QUEUE_DIRTY]); 1836 1837 while (bp) { 1838 KASSERT((bp->b_flags & B_DELWRI), ("unexpected clean buffer %p", bp)); 1839 if ((bp->b_flags & B_DELWRI) != 0 && 1840 (bp->b_xflags & BX_BKGRDINPROG) == 0) { 1841 if (bp->b_flags & B_INVAL) { 1842 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) 1843 panic("flushbufqueues: locked buf"); 1844 bremfree(bp); 1845 brelse(bp); 1846 ++r; 1847 break; 1848 } 1849 if (LIST_FIRST(&bp->b_dep) != NULL && 1850 bioops.io_countdeps && 1851 (bp->b_flags & B_DEFERRED) == 0 && 1852 (*bioops.io_countdeps)(bp, 0)) { 1853 TAILQ_REMOVE(&bufqueues[QUEUE_DIRTY], 1854 bp, b_freelist); 1855 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], 1856 bp, b_freelist); 1857 bp->b_flags |= B_DEFERRED; 1858 bp = TAILQ_FIRST(&bufqueues[QUEUE_DIRTY]); 1859 continue; 1860 } 1861 vfs_bio_awrite(bp); 1862 ++r; 1863 break; 1864 } 1865 bp = TAILQ_NEXT(bp, b_freelist); 1866 } 1867 return (r); 1868} 1869 1870/* 1871 * Check to see if a block is currently memory resident. 1872 */ 1873struct buf * 1874incore(struct vnode * vp, daddr_t blkno) 1875{ 1876 struct buf *bp; 1877 1878 int s = splbio(); 1879 bp = gbincore(vp, blkno); 1880 splx(s); 1881 return (bp); 1882} 1883 1884/* 1885 * Returns true if no I/O is needed to access the 1886 * associated VM object. This is like incore except 1887 * it also hunts around in the VM system for the data. 1888 */ 1889 1890int 1891inmem(struct vnode * vp, daddr_t blkno) 1892{ 1893 vm_object_t obj; 1894 vm_offset_t toff, tinc, size; 1895 vm_page_t m; 1896 vm_ooffset_t off; 1897 1898 if (incore(vp, blkno)) 1899 return 1; 1900 if (vp->v_mount == NULL) 1901 return 0; 1902 if ((vp->v_object == NULL) || (vp->v_flag & VOBJBUF) == 0) 1903 return 0; 1904 1905 obj = vp->v_object; 1906 size = PAGE_SIZE; 1907 if (size > vp->v_mount->mnt_stat.f_iosize) 1908 size = vp->v_mount->mnt_stat.f_iosize; 1909 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 1910 1911 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 1912 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 1913 if (!m) 1914 return 0; 1915 tinc = size; 1916 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 1917 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 1918 if (vm_page_is_valid(m, 1919 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 1920 return 0; 1921 } 1922 return 1; 1923} 1924 1925/* 1926 * vfs_setdirty: 1927 * 1928 * Sets the dirty range for a buffer based on the status of the dirty 1929 * bits in the pages comprising the buffer. 1930 * 1931 * The range is limited to the size of the buffer. 1932 * 1933 * This routine is primarily used by NFS, but is generalized for the 1934 * B_VMIO case. 1935 */ 1936static void 1937vfs_setdirty(struct buf *bp) 1938{ 1939 int i; 1940 vm_object_t object; 1941 1942 /* 1943 * Degenerate case - empty buffer 1944 */ 1945 1946 if (bp->b_bufsize == 0) 1947 return; 1948 1949 /* 1950 * We qualify the scan for modified pages on whether the 1951 * object has been flushed yet. The OBJ_WRITEABLE flag 1952 * is not cleared simply by protecting pages off. 1953 */ 1954 1955 if ((bp->b_flags & B_VMIO) == 0) 1956 return; 1957 1958 object = bp->b_pages[0]->object; 1959 1960 if ((object->flags & OBJ_WRITEABLE) && !(object->flags & OBJ_MIGHTBEDIRTY)) 1961 printf("Warning: object %p writeable but not mightbedirty\n", object); 1962 if (!(object->flags & OBJ_WRITEABLE) && (object->flags & OBJ_MIGHTBEDIRTY)) 1963 printf("Warning: object %p mightbedirty but not writeable\n", object); 1964 1965 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) { 1966 vm_offset_t boffset; 1967 vm_offset_t eoffset; 1968 1969 /* 1970 * test the pages to see if they have been modified directly 1971 * by users through the VM system. 1972 */ 1973 for (i = 0; i < bp->b_npages; i++) { 1974 vm_page_flag_clear(bp->b_pages[i], PG_ZERO); 1975 vm_page_test_dirty(bp->b_pages[i]); 1976 } 1977 1978 /* 1979 * Calculate the encompassing dirty range, boffset and eoffset, 1980 * (eoffset - boffset) bytes. 1981 */ 1982 1983 for (i = 0; i < bp->b_npages; i++) { 1984 if (bp->b_pages[i]->dirty) 1985 break; 1986 } 1987 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 1988 1989 for (i = bp->b_npages - 1; i >= 0; --i) { 1990 if (bp->b_pages[i]->dirty) { 1991 break; 1992 } 1993 } 1994 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 1995 1996 /* 1997 * Fit it to the buffer. 1998 */ 1999 2000 if (eoffset > bp->b_bcount) 2001 eoffset = bp->b_bcount; 2002 2003 /* 2004 * If we have a good dirty range, merge with the existing 2005 * dirty range. 2006 */ 2007 2008 if (boffset < eoffset) { 2009 if (bp->b_dirtyoff > boffset) 2010 bp->b_dirtyoff = boffset; 2011 if (bp->b_dirtyend < eoffset) 2012 bp->b_dirtyend = eoffset; 2013 } 2014 } 2015} 2016 2017/* 2018 * getblk: 2019 * 2020 * Get a block given a specified block and offset into a file/device. 2021 * The buffers B_DONE bit will be cleared on return, making it almost 2022 * ready for an I/O initiation. B_INVAL may or may not be set on 2023 * return. The caller should clear B_INVAL prior to initiating a 2024 * READ. 2025 * 2026 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2027 * an existing buffer. 2028 * 2029 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2030 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2031 * and then cleared based on the backing VM. If the previous buffer is 2032 * non-0-sized but invalid, B_CACHE will be cleared. 2033 * 2034 * If getblk() must create a new buffer, the new buffer is returned with 2035 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2036 * case it is returned with B_INVAL clear and B_CACHE set based on the 2037 * backing VM. 2038 * 2039 * getblk() also forces a VOP_BWRITE() for any B_DELWRI buffer whos 2040 * B_CACHE bit is clear. 2041 * 2042 * What this means, basically, is that the caller should use B_CACHE to 2043 * determine whether the buffer is fully valid or not and should clear 2044 * B_INVAL prior to issuing a read. If the caller intends to validate 2045 * the buffer by loading its data area with something, the caller needs 2046 * to clear B_INVAL. If the caller does this without issuing an I/O, 2047 * the caller should set B_CACHE ( as an optimization ), else the caller 2048 * should issue the I/O and biodone() will set B_CACHE if the I/O was 2049 * a write attempt or if it was a successfull read. If the caller 2050 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 2051 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 2052 */ 2053struct buf * 2054getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo) 2055{ 2056 struct buf *bp; 2057 int s; 2058 struct bufhashhdr *bh; 2059 2060 if (size > MAXBSIZE) 2061 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 2062 2063 s = splbio(); 2064loop: 2065 /* 2066 * Block if we are low on buffers. Certain processes are allowed 2067 * to completely exhaust the buffer cache. 2068 * 2069 * If this check ever becomes a bottleneck it may be better to 2070 * move it into the else, when gbincore() fails. At the moment 2071 * it isn't a problem. 2072 */ 2073 if (!curproc || (curproc->p_flag & P_BUFEXHAUST)) { 2074 if (numfreebuffers == 0) { 2075 if (!curproc) 2076 return NULL; 2077 needsbuffer |= VFS_BIO_NEED_ANY; 2078 tsleep(&needsbuffer, (PRIBIO + 4) | slpflag, "newbuf", 2079 slptimeo); 2080 } 2081 } else if (numfreebuffers < lofreebuffers) { 2082 waitfreebuffers(slpflag, slptimeo); 2083 } 2084 2085 if ((bp = gbincore(vp, blkno))) { 2086 /* 2087 * Buffer is in-core. If the buffer is not busy, it must 2088 * be on a queue. 2089 */ 2090 2091 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) { 2092 if (BUF_TIMELOCK(bp, LK_EXCLUSIVE | LK_SLEEPFAIL, 2093 "getblk", slpflag, slptimeo) == ENOLCK) 2094 goto loop; 2095 splx(s); 2096 return (struct buf *) NULL; 2097 } 2098 2099 /* 2100 * The buffer is locked. B_CACHE is cleared if the buffer is 2101 * invalid. Ohterwise, for a non-VMIO buffer, B_CACHE is set 2102 * and for a VMIO buffer B_CACHE is adjusted according to the 2103 * backing VM cache. 2104 */ 2105 if (bp->b_flags & B_INVAL) 2106 bp->b_flags &= ~B_CACHE; 2107 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 2108 bp->b_flags |= B_CACHE; 2109 bremfree(bp); 2110 2111 /* 2112 * check for size inconsistancies for non-VMIO case. 2113 */ 2114 2115 if (bp->b_bcount != size) { 2116 if ((bp->b_flags & B_VMIO) == 0 || 2117 (size > bp->b_kvasize)) { 2118 if (bp->b_flags & B_DELWRI) { 2119 bp->b_flags |= B_NOCACHE; 2120 BUF_WRITE(bp); 2121 } else { 2122 if ((bp->b_flags & B_VMIO) && 2123 (LIST_FIRST(&bp->b_dep) == NULL)) { 2124 bp->b_flags |= B_RELBUF; 2125 brelse(bp); 2126 } else { 2127 bp->b_flags |= B_NOCACHE; 2128 BUF_WRITE(bp); 2129 } 2130 } 2131 goto loop; 2132 } 2133 } 2134 2135 /* 2136 * If the size is inconsistant in the VMIO case, we can resize 2137 * the buffer. This might lead to B_CACHE getting set or 2138 * cleared. If the size has not changed, B_CACHE remains 2139 * unchanged from its previous state. 2140 */ 2141 2142 if (bp->b_bcount != size) 2143 allocbuf(bp, size); 2144 2145 KASSERT(bp->b_offset != NOOFFSET, 2146 ("getblk: no buffer offset")); 2147 2148 /* 2149 * A buffer with B_DELWRI set and B_CACHE clear must 2150 * be committed before we can return the buffer in 2151 * order to prevent the caller from issuing a read 2152 * ( due to B_CACHE not being set ) and overwriting 2153 * it. 2154 * 2155 * Most callers, including NFS and FFS, need this to 2156 * operate properly either because they assume they 2157 * can issue a read if B_CACHE is not set, or because 2158 * ( for example ) an uncached B_DELWRI might loop due 2159 * to softupdates re-dirtying the buffer. In the latter 2160 * case, B_CACHE is set after the first write completes, 2161 * preventing further loops. 2162 */ 2163 2164 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 2165 BUF_WRITE(bp); 2166 goto loop; 2167 } 2168 2169 splx(s); 2170 bp->b_flags &= ~B_DONE; 2171 } else { 2172 /* 2173 * Buffer is not in-core, create new buffer. The buffer 2174 * returned by getnewbuf() is locked. Note that the returned 2175 * buffer is also considered valid (not marked B_INVAL). 2176 */ 2177 int bsize, maxsize, vmio; 2178 off_t offset; 2179 2180 if (vn_isdisk(vp, NULL)) 2181 bsize = DEV_BSIZE; 2182 else if (vp->v_mountedhere) 2183 bsize = vp->v_mountedhere->mnt_stat.f_iosize; 2184 else if (vp->v_mount) 2185 bsize = vp->v_mount->mnt_stat.f_iosize; 2186 else 2187 bsize = size; 2188 2189 offset = (off_t)blkno * bsize; 2190 vmio = (vp->v_object != 0) && (vp->v_flag & VOBJBUF); 2191 maxsize = vmio ? size + (offset & PAGE_MASK) : size; 2192 maxsize = imax(maxsize, bsize); 2193 2194 if ((bp = getnewbuf(slpflag, slptimeo, size, maxsize)) == NULL) { 2195 if (slpflag || slptimeo) { 2196 splx(s); 2197 return NULL; 2198 } 2199 goto loop; 2200 } 2201 2202 /* 2203 * This code is used to make sure that a buffer is not 2204 * created while the getnewbuf routine is blocked. 2205 * This can be a problem whether the vnode is locked or not. 2206 * If the buffer is created out from under us, we have to 2207 * throw away the one we just created. There is now window 2208 * race because we are safely running at splbio() from the 2209 * point of the duplicate buffer creation through to here, 2210 * and we've locked the buffer. 2211 */ 2212 if (gbincore(vp, blkno)) { 2213 bp->b_flags |= B_INVAL; 2214 brelse(bp); 2215 goto loop; 2216 } 2217 2218 /* 2219 * Insert the buffer into the hash, so that it can 2220 * be found by incore. 2221 */ 2222 bp->b_blkno = bp->b_lblkno = blkno; 2223 bp->b_offset = offset; 2224 2225 bgetvp(vp, bp); 2226 LIST_REMOVE(bp, b_hash); 2227 bh = bufhash(vp, blkno); 2228 LIST_INSERT_HEAD(bh, bp, b_hash); 2229 2230 /* 2231 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 2232 * buffer size starts out as 0, B_CACHE will be set by 2233 * allocbuf() for the VMIO case prior to it testing the 2234 * backing store for validity. 2235 */ 2236 2237 if (vmio) { 2238 bp->b_flags |= B_VMIO; 2239#if defined(VFS_BIO_DEBUG) 2240 if (vp->v_type != VREG && vp->v_type != VBLK) 2241 printf("getblk: vmioing file type %d???\n", vp->v_type); 2242#endif 2243 } else { 2244 bp->b_flags &= ~B_VMIO; 2245 } 2246 2247 allocbuf(bp, size); 2248 2249 splx(s); 2250 bp->b_flags &= ~B_DONE; 2251 } 2252 return (bp); 2253} 2254 2255/* 2256 * Get an empty, disassociated buffer of given size. The buffer is initially 2257 * set to B_INVAL. 2258 */ 2259struct buf * 2260geteblk(int size) 2261{ 2262 struct buf *bp; 2263 int s; 2264 int maxsize; 2265 2266 maxsize = (size + BKVAMASK) & ~BKVAMASK; 2267 2268 s = splbio(); 2269 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0); 2270 splx(s); 2271 allocbuf(bp, size); 2272 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 2273 return (bp); 2274} 2275 2276 2277/* 2278 * This code constitutes the buffer memory from either anonymous system 2279 * memory (in the case of non-VMIO operations) or from an associated 2280 * VM object (in the case of VMIO operations). This code is able to 2281 * resize a buffer up or down. 2282 * 2283 * Note that this code is tricky, and has many complications to resolve 2284 * deadlock or inconsistant data situations. Tread lightly!!! 2285 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 2286 * the caller. Calling this code willy nilly can result in the loss of data. 2287 * 2288 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 2289 * B_CACHE for the non-VMIO case. 2290 */ 2291 2292int 2293allocbuf(struct buf *bp, int size) 2294{ 2295 int newbsize, mbsize; 2296 int i; 2297 2298 if (BUF_REFCNT(bp) == 0) 2299 panic("allocbuf: buffer not busy"); 2300 2301 if (bp->b_kvasize < size) 2302 panic("allocbuf: buffer too small"); 2303 2304 if ((bp->b_flags & B_VMIO) == 0) { 2305 caddr_t origbuf; 2306 int origbufsize; 2307 /* 2308 * Just get anonymous memory from the kernel. Don't 2309 * mess with B_CACHE. 2310 */ 2311 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2312#if !defined(NO_B_MALLOC) 2313 if (bp->b_flags & B_MALLOC) 2314 newbsize = mbsize; 2315 else 2316#endif 2317 newbsize = round_page(size); 2318 2319 if (newbsize < bp->b_bufsize) { 2320#if !defined(NO_B_MALLOC) 2321 /* 2322 * malloced buffers are not shrunk 2323 */ 2324 if (bp->b_flags & B_MALLOC) { 2325 if (newbsize) { 2326 bp->b_bcount = size; 2327 } else { 2328 free(bp->b_data, M_BIOBUF); 2329 bufmallocspace -= bp->b_bufsize; 2330 runningbufspace -= bp->b_bufsize; 2331 if (bp->b_bufsize) 2332 bufspacewakeup(); 2333 bp->b_data = bp->b_kvabase; 2334 bp->b_bufsize = 0; 2335 bp->b_bcount = 0; 2336 bp->b_flags &= ~B_MALLOC; 2337 } 2338 return 1; 2339 } 2340#endif 2341 vm_hold_free_pages( 2342 bp, 2343 (vm_offset_t) bp->b_data + newbsize, 2344 (vm_offset_t) bp->b_data + bp->b_bufsize); 2345 } else if (newbsize > bp->b_bufsize) { 2346#if !defined(NO_B_MALLOC) 2347 /* 2348 * We only use malloced memory on the first allocation. 2349 * and revert to page-allocated memory when the buffer 2350 * grows. 2351 */ 2352 if ( (bufmallocspace < maxbufmallocspace) && 2353 (bp->b_bufsize == 0) && 2354 (mbsize <= PAGE_SIZE/2)) { 2355 2356 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 2357 bp->b_bufsize = mbsize; 2358 bp->b_bcount = size; 2359 bp->b_flags |= B_MALLOC; 2360 bufmallocspace += mbsize; 2361 runningbufspace += bp->b_bufsize; 2362 return 1; 2363 } 2364#endif 2365 origbuf = NULL; 2366 origbufsize = 0; 2367#if !defined(NO_B_MALLOC) 2368 /* 2369 * If the buffer is growing on its other-than-first allocation, 2370 * then we revert to the page-allocation scheme. 2371 */ 2372 if (bp->b_flags & B_MALLOC) { 2373 origbuf = bp->b_data; 2374 origbufsize = bp->b_bufsize; 2375 bp->b_data = bp->b_kvabase; 2376 bufmallocspace -= bp->b_bufsize; 2377 runningbufspace -= bp->b_bufsize; 2378 if (bp->b_bufsize) 2379 bufspacewakeup(); 2380 bp->b_bufsize = 0; 2381 bp->b_flags &= ~B_MALLOC; 2382 newbsize = round_page(newbsize); 2383 } 2384#endif 2385 vm_hold_load_pages( 2386 bp, 2387 (vm_offset_t) bp->b_data + bp->b_bufsize, 2388 (vm_offset_t) bp->b_data + newbsize); 2389#if !defined(NO_B_MALLOC) 2390 if (origbuf) { 2391 bcopy(origbuf, bp->b_data, origbufsize); 2392 free(origbuf, M_BIOBUF); 2393 } 2394#endif 2395 } 2396 } else { 2397 vm_page_t m; 2398 int desiredpages; 2399 2400 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2401 desiredpages = (size == 0) ? 0 : 2402 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 2403 2404#if !defined(NO_B_MALLOC) 2405 if (bp->b_flags & B_MALLOC) 2406 panic("allocbuf: VMIO buffer can't be malloced"); 2407#endif 2408 /* 2409 * Set B_CACHE initially if buffer is 0 length or will become 2410 * 0-length. 2411 */ 2412 if (size == 0 || bp->b_bufsize == 0) 2413 bp->b_flags |= B_CACHE; 2414 2415 if (newbsize < bp->b_bufsize) { 2416 /* 2417 * DEV_BSIZE aligned new buffer size is less then the 2418 * DEV_BSIZE aligned existing buffer size. Figure out 2419 * if we have to remove any pages. 2420 */ 2421 if (desiredpages < bp->b_npages) { 2422 for (i = desiredpages; i < bp->b_npages; i++) { 2423 /* 2424 * the page is not freed here -- it 2425 * is the responsibility of 2426 * vnode_pager_setsize 2427 */ 2428 m = bp->b_pages[i]; 2429 KASSERT(m != bogus_page, 2430 ("allocbuf: bogus page found")); 2431 while (vm_page_sleep_busy(m, TRUE, "biodep")) 2432 ; 2433 2434 bp->b_pages[i] = NULL; 2435 vm_page_unwire(m, 0); 2436 } 2437 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) + 2438 (desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages)); 2439 bp->b_npages = desiredpages; 2440 } 2441 } else if (size > bp->b_bcount) { 2442 /* 2443 * We are growing the buffer, possibly in a 2444 * byte-granular fashion. 2445 */ 2446 struct vnode *vp; 2447 vm_object_t obj; 2448 vm_offset_t toff; 2449 vm_offset_t tinc; 2450 2451 /* 2452 * Step 1, bring in the VM pages from the object, 2453 * allocating them if necessary. We must clear 2454 * B_CACHE if these pages are not valid for the 2455 * range covered by the buffer. 2456 */ 2457 2458 vp = bp->b_vp; 2459 obj = vp->v_object; 2460 2461 while (bp->b_npages < desiredpages) { 2462 vm_page_t m; 2463 vm_pindex_t pi; 2464 2465 pi = OFF_TO_IDX(bp->b_offset) + bp->b_npages; 2466 if ((m = vm_page_lookup(obj, pi)) == NULL) { 2467 m = vm_page_alloc(obj, pi, VM_ALLOC_NORMAL); 2468 if (m == NULL) { 2469 VM_WAIT; 2470 vm_pageout_deficit += desiredpages - bp->b_npages; 2471 } else { 2472 vm_page_wire(m); 2473 vm_page_wakeup(m); 2474 bp->b_flags &= ~B_CACHE; 2475 bp->b_pages[bp->b_npages] = m; 2476 ++bp->b_npages; 2477 } 2478 continue; 2479 } 2480 2481 /* 2482 * We found a page. If we have to sleep on it, 2483 * retry because it might have gotten freed out 2484 * from under us. 2485 * 2486 * We can only test PG_BUSY here. Blocking on 2487 * m->busy might lead to a deadlock: 2488 * 2489 * vm_fault->getpages->cluster_read->allocbuf 2490 * 2491 */ 2492 2493 if (vm_page_sleep_busy(m, FALSE, "pgtblk")) 2494 continue; 2495 2496 /* 2497 * We have a good page. Should we wakeup the 2498 * page daemon? 2499 */ 2500 if ((curproc != pageproc) && 2501 ((m->queue - m->pc) == PQ_CACHE) && 2502 ((cnt.v_free_count + cnt.v_cache_count) < 2503 (cnt.v_free_min + cnt.v_cache_min))) { 2504 pagedaemon_wakeup(); 2505 } 2506 vm_page_flag_clear(m, PG_ZERO); 2507 vm_page_wire(m); 2508 bp->b_pages[bp->b_npages] = m; 2509 ++bp->b_npages; 2510 } 2511 2512 /* 2513 * Step 2. We've loaded the pages into the buffer, 2514 * we have to figure out if we can still have B_CACHE 2515 * set. Note that B_CACHE is set according to the 2516 * byte-granular range ( bcount and size ), new the 2517 * aligned range ( newbsize ). 2518 * 2519 * The VM test is against m->valid, which is DEV_BSIZE 2520 * aligned. Needless to say, the validity of the data 2521 * needs to also be DEV_BSIZE aligned. Note that this 2522 * fails with NFS if the server or some other client 2523 * extends the file's EOF. If our buffer is resized, 2524 * B_CACHE may remain set! XXX 2525 */ 2526 2527 toff = bp->b_bcount; 2528 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 2529 2530 while ((bp->b_flags & B_CACHE) && toff < size) { 2531 vm_pindex_t pi; 2532 2533 if (tinc > (size - toff)) 2534 tinc = size - toff; 2535 2536 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 2537 PAGE_SHIFT; 2538 2539 vfs_buf_test_cache( 2540 bp, 2541 bp->b_offset, 2542 toff, 2543 tinc, 2544 bp->b_pages[pi] 2545 ); 2546 toff += tinc; 2547 tinc = PAGE_SIZE; 2548 } 2549 2550 /* 2551 * Step 3, fixup the KVM pmap. Remember that 2552 * bp->b_data is relative to bp->b_offset, but 2553 * bp->b_offset may be offset into the first page. 2554 */ 2555 2556 bp->b_data = (caddr_t) 2557 trunc_page((vm_offset_t)bp->b_data); 2558 pmap_qenter( 2559 (vm_offset_t)bp->b_data, 2560 bp->b_pages, 2561 bp->b_npages 2562 ); 2563 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 2564 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 2565 } 2566 } 2567 runningbufspace += (newbsize - bp->b_bufsize); 2568 if (newbsize < bp->b_bufsize) 2569 bufspacewakeup(); 2570 bp->b_bufsize = newbsize; /* actual buffer allocation */ 2571 bp->b_bcount = size; /* requested buffer size */ 2572 return 1; 2573} 2574 2575/* 2576 * bufwait: 2577 * 2578 * Wait for buffer I/O completion, returning error status. The buffer 2579 * is left locked and B_DONE on return. B_EINTR is converted into a EINTR 2580 * error and cleared. 2581 */ 2582int 2583bufwait(register struct buf * bp) 2584{ 2585 int s; 2586 2587 s = splbio(); 2588 while ((bp->b_flags & B_DONE) == 0) { 2589 if (bp->b_iocmd == BIO_READ) 2590 tsleep(bp, PRIBIO, "biord", 0); 2591 else 2592 tsleep(bp, PRIBIO, "biowr", 0); 2593 } 2594 splx(s); 2595 if (bp->b_flags & B_EINTR) { 2596 bp->b_flags &= ~B_EINTR; 2597 return (EINTR); 2598 } 2599 if (bp->b_ioflags & BIO_ERROR) { 2600 return (bp->b_error ? bp->b_error : EIO); 2601 } else { 2602 return (0); 2603 } 2604} 2605 2606 /* 2607 * Call back function from struct bio back up to struct buf. 2608 * The corresponding initialization lives in sys/conf.h:DEV_STRATEGY(). 2609 */ 2610void 2611bufdonebio(struct bio *bp) 2612{ 2613 bufdone(bp->bio_caller2); 2614} 2615 2616/* 2617 * bufdone: 2618 * 2619 * Finish I/O on a buffer, optionally calling a completion function. 2620 * This is usually called from an interrupt so process blocking is 2621 * not allowed. 2622 * 2623 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 2624 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 2625 * assuming B_INVAL is clear. 2626 * 2627 * For the VMIO case, we set B_CACHE if the op was a read and no 2628 * read error occured, or if the op was a write. B_CACHE is never 2629 * set if the buffer is invalid or otherwise uncacheable. 2630 * 2631 * biodone does not mess with B_INVAL, allowing the I/O routine or the 2632 * initiator to leave B_INVAL set to brelse the buffer out of existance 2633 * in the biodone routine. 2634 */ 2635void 2636bufdone(struct buf *bp) 2637{ 2638 int s; 2639 void (*biodone) __P((struct buf *)); 2640 2641 s = splbio(); 2642 2643 KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp, BUF_REFCNT(bp))); 2644 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 2645 2646 bp->b_flags |= B_DONE; 2647 2648 if (bp->b_iocmd == BIO_DELETE) { 2649 brelse(bp); 2650 splx(s); 2651 return; 2652 } 2653 2654 if (bp->b_iocmd == BIO_WRITE) { 2655 vwakeup(bp); 2656 } 2657 2658 /* call optional completion function if requested */ 2659 if (bp->b_iodone != NULL) { 2660 biodone = bp->b_iodone; 2661 bp->b_iodone = NULL; 2662 (*biodone) (bp); 2663 splx(s); 2664 return; 2665 } 2666 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_complete) 2667 (*bioops.io_complete)(bp); 2668 2669 if (bp->b_flags & B_VMIO) { 2670 int i, resid; 2671 vm_ooffset_t foff; 2672 vm_page_t m; 2673 vm_object_t obj; 2674 int iosize; 2675 struct vnode *vp = bp->b_vp; 2676 2677 obj = vp->v_object; 2678 2679#if defined(VFS_BIO_DEBUG) 2680 if (vp->v_usecount == 0) { 2681 panic("biodone: zero vnode ref count"); 2682 } 2683 2684 if (vp->v_object == NULL) { 2685 panic("biodone: missing VM object"); 2686 } 2687 2688 if ((vp->v_flag & VOBJBUF) == 0) { 2689 panic("biodone: vnode is not setup for merged cache"); 2690 } 2691#endif 2692 2693 foff = bp->b_offset; 2694 KASSERT(bp->b_offset != NOOFFSET, 2695 ("biodone: no buffer offset")); 2696 2697 if (!obj) { 2698 panic("biodone: no object"); 2699 } 2700#if defined(VFS_BIO_DEBUG) 2701 if (obj->paging_in_progress < bp->b_npages) { 2702 printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n", 2703 obj->paging_in_progress, bp->b_npages); 2704 } 2705#endif 2706 2707 /* 2708 * Set B_CACHE if the op was a normal read and no error 2709 * occured. B_CACHE is set for writes in the b*write() 2710 * routines. 2711 */ 2712 iosize = bp->b_bcount - bp->b_resid; 2713 if (bp->b_iocmd == BIO_READ && 2714 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 2715 !(bp->b_ioflags & BIO_ERROR)) { 2716 bp->b_flags |= B_CACHE; 2717 } 2718 2719 for (i = 0; i < bp->b_npages; i++) { 2720 int bogusflag = 0; 2721 m = bp->b_pages[i]; 2722 if (m == bogus_page) { 2723 bogusflag = 1; 2724 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 2725 if (!m) { 2726#if defined(VFS_BIO_DEBUG) 2727 printf("biodone: page disappeared\n"); 2728#endif 2729 vm_object_pip_subtract(obj, 1); 2730 bp->b_flags &= ~B_CACHE; 2731 continue; 2732 } 2733 bp->b_pages[i] = m; 2734 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 2735 } 2736#if defined(VFS_BIO_DEBUG) 2737 if (OFF_TO_IDX(foff) != m->pindex) { 2738 printf( 2739"biodone: foff(%lu)/m->pindex(%d) mismatch\n", 2740 (unsigned long)foff, m->pindex); 2741 } 2742#endif 2743 resid = IDX_TO_OFF(m->pindex + 1) - foff; 2744 if (resid > iosize) 2745 resid = iosize; 2746 2747 /* 2748 * In the write case, the valid and clean bits are 2749 * already changed correctly ( see bdwrite() ), so we 2750 * only need to do this here in the read case. 2751 */ 2752 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 2753 vfs_page_set_valid(bp, foff, i, m); 2754 } 2755 vm_page_flag_clear(m, PG_ZERO); 2756 2757 /* 2758 * when debugging new filesystems or buffer I/O methods, this 2759 * is the most common error that pops up. if you see this, you 2760 * have not set the page busy flag correctly!!! 2761 */ 2762 if (m->busy == 0) { 2763 printf("biodone: page busy < 0, " 2764 "pindex: %d, foff: 0x(%x,%x), " 2765 "resid: %d, index: %d\n", 2766 (int) m->pindex, (int)(foff >> 32), 2767 (int) foff & 0xffffffff, resid, i); 2768 if (!vn_isdisk(vp, NULL)) 2769 printf(" iosize: %ld, lblkno: %d, flags: 0x%lx, npages: %d\n", 2770 bp->b_vp->v_mount->mnt_stat.f_iosize, 2771 (int) bp->b_lblkno, 2772 bp->b_flags, bp->b_npages); 2773 else 2774 printf(" VDEV, lblkno: %d, flags: 0x%lx, npages: %d\n", 2775 (int) bp->b_lblkno, 2776 bp->b_flags, bp->b_npages); 2777 printf(" valid: 0x%x, dirty: 0x%x, wired: %d\n", 2778 m->valid, m->dirty, m->wire_count); 2779 panic("biodone: page busy < 0\n"); 2780 } 2781 vm_page_io_finish(m); 2782 vm_object_pip_subtract(obj, 1); 2783 foff += resid; 2784 iosize -= resid; 2785 } 2786 if (obj) 2787 vm_object_pip_wakeupn(obj, 0); 2788 } 2789 /* 2790 * For asynchronous completions, release the buffer now. The brelse 2791 * will do a wakeup there if necessary - so no need to do a wakeup 2792 * here in the async case. The sync case always needs to do a wakeup. 2793 */ 2794 2795 if (bp->b_flags & B_ASYNC) { 2796 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 2797 brelse(bp); 2798 else 2799 bqrelse(bp); 2800 } else { 2801 wakeup(bp); 2802 } 2803 splx(s); 2804} 2805 2806/* 2807 * This routine is called in lieu of iodone in the case of 2808 * incomplete I/O. This keeps the busy status for pages 2809 * consistant. 2810 */ 2811void 2812vfs_unbusy_pages(struct buf * bp) 2813{ 2814 int i; 2815 2816 if (bp->b_flags & B_VMIO) { 2817 struct vnode *vp = bp->b_vp; 2818 vm_object_t obj = vp->v_object; 2819 2820 for (i = 0; i < bp->b_npages; i++) { 2821 vm_page_t m = bp->b_pages[i]; 2822 2823 if (m == bogus_page) { 2824 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 2825 if (!m) { 2826 panic("vfs_unbusy_pages: page missing\n"); 2827 } 2828 bp->b_pages[i] = m; 2829 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 2830 } 2831 vm_object_pip_subtract(obj, 1); 2832 vm_page_flag_clear(m, PG_ZERO); 2833 vm_page_io_finish(m); 2834 } 2835 vm_object_pip_wakeupn(obj, 0); 2836 } 2837} 2838 2839/* 2840 * vfs_page_set_valid: 2841 * 2842 * Set the valid bits in a page based on the supplied offset. The 2843 * range is restricted to the buffer's size. 2844 * 2845 * This routine is typically called after a read completes. 2846 */ 2847static void 2848vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m) 2849{ 2850 vm_ooffset_t soff, eoff; 2851 2852 /* 2853 * Start and end offsets in buffer. eoff - soff may not cross a 2854 * page boundry or cross the end of the buffer. The end of the 2855 * buffer, in this case, is our file EOF, not the allocation size 2856 * of the buffer. 2857 */ 2858 soff = off; 2859 eoff = (off + PAGE_SIZE) & ~PAGE_MASK; 2860 if (eoff > bp->b_offset + bp->b_bcount) 2861 eoff = bp->b_offset + bp->b_bcount; 2862 2863 /* 2864 * Set valid range. This is typically the entire buffer and thus the 2865 * entire page. 2866 */ 2867 if (eoff > soff) { 2868 vm_page_set_validclean( 2869 m, 2870 (vm_offset_t) (soff & PAGE_MASK), 2871 (vm_offset_t) (eoff - soff) 2872 ); 2873 } 2874} 2875 2876/* 2877 * This routine is called before a device strategy routine. 2878 * It is used to tell the VM system that paging I/O is in 2879 * progress, and treat the pages associated with the buffer 2880 * almost as being PG_BUSY. Also the object paging_in_progress 2881 * flag is handled to make sure that the object doesn't become 2882 * inconsistant. 2883 * 2884 * Since I/O has not been initiated yet, certain buffer flags 2885 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 2886 * and should be ignored. 2887 */ 2888void 2889vfs_busy_pages(struct buf * bp, int clear_modify) 2890{ 2891 int i, bogus; 2892 2893 if (bp->b_flags & B_VMIO) { 2894 struct vnode *vp = bp->b_vp; 2895 vm_object_t obj = vp->v_object; 2896 vm_ooffset_t foff; 2897 2898 foff = bp->b_offset; 2899 KASSERT(bp->b_offset != NOOFFSET, 2900 ("vfs_busy_pages: no buffer offset")); 2901 vfs_setdirty(bp); 2902 2903retry: 2904 for (i = 0; i < bp->b_npages; i++) { 2905 vm_page_t m = bp->b_pages[i]; 2906 if (vm_page_sleep_busy(m, FALSE, "vbpage")) 2907 goto retry; 2908 } 2909 2910 bogus = 0; 2911 for (i = 0; i < bp->b_npages; i++) { 2912 vm_page_t m = bp->b_pages[i]; 2913 2914 vm_page_flag_clear(m, PG_ZERO); 2915 if ((bp->b_flags & B_CLUSTER) == 0) { 2916 vm_object_pip_add(obj, 1); 2917 vm_page_io_start(m); 2918 } 2919 2920 /* 2921 * When readying a buffer for a read ( i.e 2922 * clear_modify == 0 ), it is important to do 2923 * bogus_page replacement for valid pages in 2924 * partially instantiated buffers. Partially 2925 * instantiated buffers can, in turn, occur when 2926 * reconstituting a buffer from its VM backing store 2927 * base. We only have to do this if B_CACHE is 2928 * clear ( which causes the I/O to occur in the 2929 * first place ). The replacement prevents the read 2930 * I/O from overwriting potentially dirty VM-backed 2931 * pages. XXX bogus page replacement is, uh, bogus. 2932 * It may not work properly with small-block devices. 2933 * We need to find a better way. 2934 */ 2935 2936 vm_page_protect(m, VM_PROT_NONE); 2937 if (clear_modify) 2938 vfs_page_set_valid(bp, foff, i, m); 2939 else if (m->valid == VM_PAGE_BITS_ALL && 2940 (bp->b_flags & B_CACHE) == 0) { 2941 bp->b_pages[i] = bogus_page; 2942 bogus++; 2943 } 2944 foff = (foff + PAGE_SIZE) & ~PAGE_MASK; 2945 } 2946 if (bogus) 2947 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 2948 } 2949} 2950 2951/* 2952 * Tell the VM system that the pages associated with this buffer 2953 * are clean. This is used for delayed writes where the data is 2954 * going to go to disk eventually without additional VM intevention. 2955 * 2956 * Note that while we only really need to clean through to b_bcount, we 2957 * just go ahead and clean through to b_bufsize. 2958 */ 2959static void 2960vfs_clean_pages(struct buf * bp) 2961{ 2962 int i; 2963 2964 if (bp->b_flags & B_VMIO) { 2965 vm_ooffset_t foff; 2966 2967 foff = bp->b_offset; 2968 KASSERT(bp->b_offset != NOOFFSET, 2969 ("vfs_clean_pages: no buffer offset")); 2970 for (i = 0; i < bp->b_npages; i++) { 2971 vm_page_t m = bp->b_pages[i]; 2972 vm_ooffset_t noff = (foff + PAGE_SIZE) & ~PAGE_MASK; 2973 vm_ooffset_t eoff = noff; 2974 2975 if (eoff > bp->b_offset + bp->b_bufsize) 2976 eoff = bp->b_offset + bp->b_bufsize; 2977 vfs_page_set_valid(bp, foff, i, m); 2978 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 2979 foff = noff; 2980 } 2981 } 2982} 2983 2984/* 2985 * vfs_bio_set_validclean: 2986 * 2987 * Set the range within the buffer to valid and clean. The range is 2988 * relative to the beginning of the buffer, b_offset. Note that b_offset 2989 * itself may be offset from the beginning of the first page. 2990 */ 2991 2992void 2993vfs_bio_set_validclean(struct buf *bp, int base, int size) 2994{ 2995 if (bp->b_flags & B_VMIO) { 2996 int i; 2997 int n; 2998 2999 /* 3000 * Fixup base to be relative to beginning of first page. 3001 * Set initial n to be the maximum number of bytes in the 3002 * first page that can be validated. 3003 */ 3004 3005 base += (bp->b_offset & PAGE_MASK); 3006 n = PAGE_SIZE - (base & PAGE_MASK); 3007 3008 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 3009 vm_page_t m = bp->b_pages[i]; 3010 3011 if (n > size) 3012 n = size; 3013 3014 vm_page_set_validclean(m, base & PAGE_MASK, n); 3015 base += n; 3016 size -= n; 3017 n = PAGE_SIZE; 3018 } 3019 } 3020} 3021 3022/* 3023 * vfs_bio_clrbuf: 3024 * 3025 * clear a buffer. This routine essentially fakes an I/O, so we need 3026 * to clear BIO_ERROR and B_INVAL. 3027 * 3028 * Note that while we only theoretically need to clear through b_bcount, 3029 * we go ahead and clear through b_bufsize. 3030 */ 3031 3032void 3033vfs_bio_clrbuf(struct buf *bp) { 3034 int i, mask = 0; 3035 caddr_t sa, ea; 3036 if ((bp->b_flags & (B_VMIO | B_MALLOC)) == B_VMIO) { 3037 bp->b_flags &= ~B_INVAL; 3038 bp->b_ioflags &= ~BIO_ERROR; 3039 if( (bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 3040 (bp->b_offset & PAGE_MASK) == 0) { 3041 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 3042 if (((bp->b_pages[0]->flags & PG_ZERO) == 0) && 3043 ((bp->b_pages[0]->valid & mask) != mask)) { 3044 bzero(bp->b_data, bp->b_bufsize); 3045 } 3046 bp->b_pages[0]->valid |= mask; 3047 bp->b_resid = 0; 3048 return; 3049 } 3050 ea = sa = bp->b_data; 3051 for(i=0;i<bp->b_npages;i++,sa=ea) { 3052 int j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; 3053 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); 3054 ea = (caddr_t)(vm_offset_t)ulmin( 3055 (u_long)(vm_offset_t)ea, 3056 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); 3057 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 3058 if ((bp->b_pages[i]->valid & mask) == mask) 3059 continue; 3060 if ((bp->b_pages[i]->valid & mask) == 0) { 3061 if ((bp->b_pages[i]->flags & PG_ZERO) == 0) { 3062 bzero(sa, ea - sa); 3063 } 3064 } else { 3065 for (; sa < ea; sa += DEV_BSIZE, j++) { 3066 if (((bp->b_pages[i]->flags & PG_ZERO) == 0) && 3067 (bp->b_pages[i]->valid & (1<<j)) == 0) 3068 bzero(sa, DEV_BSIZE); 3069 } 3070 } 3071 bp->b_pages[i]->valid |= mask; 3072 vm_page_flag_clear(bp->b_pages[i], PG_ZERO); 3073 } 3074 bp->b_resid = 0; 3075 } else { 3076 clrbuf(bp); 3077 } 3078} 3079 3080/* 3081 * vm_hold_load_pages and vm_hold_unload pages get pages into 3082 * a buffers address space. The pages are anonymous and are 3083 * not associated with a file object. 3084 */ 3085void 3086vm_hold_load_pages(struct buf * bp, vm_offset_t from, vm_offset_t to) 3087{ 3088 vm_offset_t pg; 3089 vm_page_t p; 3090 int index; 3091 3092 to = round_page(to); 3093 from = round_page(from); 3094 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3095 3096 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3097 3098tryagain: 3099 3100 p = vm_page_alloc(kernel_object, 3101 ((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 3102 VM_ALLOC_NORMAL); 3103 if (!p) { 3104 vm_pageout_deficit += (to - from) >> PAGE_SHIFT; 3105 VM_WAIT; 3106 goto tryagain; 3107 } 3108 vm_page_wire(p); 3109 p->valid = VM_PAGE_BITS_ALL; 3110 vm_page_flag_clear(p, PG_ZERO); 3111 pmap_kenter(pg, VM_PAGE_TO_PHYS(p)); 3112 bp->b_pages[index] = p; 3113 vm_page_wakeup(p); 3114 } 3115 bp->b_npages = index; 3116} 3117 3118void 3119vm_hold_free_pages(struct buf * bp, vm_offset_t from, vm_offset_t to) 3120{ 3121 vm_offset_t pg; 3122 vm_page_t p; 3123 int index, newnpages; 3124 3125 from = round_page(from); 3126 to = round_page(to); 3127 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3128 3129 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3130 p = bp->b_pages[index]; 3131 if (p && (index < bp->b_npages)) { 3132 if (p->busy) { 3133 printf("vm_hold_free_pages: blkno: %d, lblkno: %d\n", 3134 bp->b_blkno, bp->b_lblkno); 3135 } 3136 bp->b_pages[index] = NULL; 3137 pmap_kremove(pg); 3138 vm_page_busy(p); 3139 vm_page_unwire(p, 0); 3140 vm_page_free(p); 3141 } 3142 } 3143 bp->b_npages = newnpages; 3144} 3145 3146 3147#include "opt_ddb.h" 3148#ifdef DDB 3149#include <ddb/ddb.h> 3150 3151DB_SHOW_COMMAND(buffer, db_show_buffer) 3152{ 3153 /* get args */ 3154 struct buf *bp = (struct buf *)addr; 3155 3156 if (!have_addr) { 3157 db_printf("usage: show buffer <addr>\n"); 3158 return; 3159 } 3160 3161 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS); 3162 db_printf("b_error = %d, b_bufsize = %ld, b_bcount = %ld, " 3163 "b_resid = %ld\nb_dev = (%d,%d), b_data = %p, " 3164 "b_blkno = %d, b_pblkno = %d\n", 3165 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 3166 major(bp->b_dev), minor(bp->b_dev), 3167 bp->b_data, bp->b_blkno, bp->b_pblkno); 3168 if (bp->b_npages) { 3169 int i; 3170 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 3171 for (i = 0; i < bp->b_npages; i++) { 3172 vm_page_t m; 3173 m = bp->b_pages[i]; 3174 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 3175 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 3176 if ((i + 1) < bp->b_npages) 3177 db_printf(","); 3178 } 3179 db_printf("\n"); 3180 } 3181} 3182#endif /* DDB */
| 33#include <sys/buf.h> 34#include <sys/eventhandler.h> 35#include <sys/lock.h> 36#include <sys/malloc.h> 37#include <sys/mount.h> 38#include <sys/kernel.h> 39#include <sys/kthread.h> 40#include <sys/proc.h> 41#include <sys/reboot.h> 42#include <sys/resourcevar.h> 43#include <sys/sysctl.h> 44#include <sys/vmmeter.h> 45#include <sys/vnode.h> 46#include <vm/vm.h> 47#include <vm/vm_param.h> 48#include <vm/vm_kern.h> 49#include <vm/vm_pageout.h> 50#include <vm/vm_page.h> 51#include <vm/vm_object.h> 52#include <vm/vm_extern.h> 53#include <vm/vm_map.h> 54 55static MALLOC_DEFINE(M_BIOBUF, "BIO buffer", "BIO buffer"); 56 57struct bio_ops bioops; /* I/O operation notification */ 58 59struct buf *buf; /* buffer header pool */ 60struct swqueue bswlist; 61struct simplelock buftimelock; /* Interlock on setting prio and timo */ 62 63static void vm_hold_free_pages(struct buf * bp, vm_offset_t from, 64 vm_offset_t to); 65static void vm_hold_load_pages(struct buf * bp, vm_offset_t from, 66 vm_offset_t to); 67static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, 68 int pageno, vm_page_t m); 69static void vfs_clean_pages(struct buf * bp); 70static void vfs_setdirty(struct buf *bp); 71static void vfs_vmio_release(struct buf *bp); 72static void vfs_backgroundwritedone(struct buf *bp); 73static int flushbufqueues(void); 74 75static int bd_request; 76 77static void buf_daemon __P((void)); 78/* 79 * bogus page -- for I/O to/from partially complete buffers 80 * this is a temporary solution to the problem, but it is not 81 * really that bad. it would be better to split the buffer 82 * for input in the case of buffers partially already in memory, 83 * but the code is intricate enough already. 84 */ 85vm_page_t bogus_page; 86int runningbufspace; 87int vmiodirenable = FALSE; 88static vm_offset_t bogus_offset; 89 90static int bufspace, maxbufspace, 91 bufmallocspace, maxbufmallocspace, lobufspace, hibufspace; 92static int bufreusecnt, bufdefragcnt, buffreekvacnt; 93static int maxbdrun; 94static int needsbuffer; 95static int numdirtybuffers, hidirtybuffers; 96static int numfreebuffers, lofreebuffers, hifreebuffers; 97static int getnewbufcalls; 98static int getnewbufrestarts; 99 100SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, 101 &numdirtybuffers, 0, ""); 102SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, 103 &hidirtybuffers, 0, ""); 104SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, 105 &numfreebuffers, 0, ""); 106SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, 107 &lofreebuffers, 0, ""); 108SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, 109 &hifreebuffers, 0, ""); 110SYSCTL_INT(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, 111 &runningbufspace, 0, ""); 112SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, 113 &maxbufspace, 0, ""); 114SYSCTL_INT(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, 115 &hibufspace, 0, ""); 116SYSCTL_INT(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, 117 &lobufspace, 0, ""); 118SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, 119 &bufspace, 0, ""); 120SYSCTL_INT(_vfs, OID_AUTO, maxbdrun, CTLFLAG_RW, 121 &maxbdrun, 0, ""); 122SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, 123 &maxbufmallocspace, 0, ""); 124SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, 125 &bufmallocspace, 0, ""); 126SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, 127 &getnewbufcalls, 0, ""); 128SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, 129 &getnewbufrestarts, 0, ""); 130SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, 131 &vmiodirenable, 0, ""); 132SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, 133 &bufdefragcnt, 0, ""); 134SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, 135 &buffreekvacnt, 0, ""); 136SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, 137 &bufreusecnt, 0, ""); 138 139static int bufhashmask; 140static LIST_HEAD(bufhashhdr, buf) *bufhashtbl, invalhash; 141struct bqueues bufqueues[BUFFER_QUEUES] = { { 0 } }; 142char *buf_wmesg = BUF_WMESG; 143 144extern int vm_swap_size; 145 146#define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 147#define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */ 148#define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ 149#define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 150 151/* 152 * Buffer hash table code. Note that the logical block scans linearly, which 153 * gives us some L1 cache locality. 154 */ 155 156static __inline 157struct bufhashhdr * 158bufhash(struct vnode *vnp, daddr_t bn) 159{ 160 return(&bufhashtbl[(((uintptr_t)(vnp) >> 7) + (int)bn) & bufhashmask]); 161} 162 163/* 164 * numdirtywakeup: 165 * 166 * If someone is blocked due to there being too many dirty buffers, 167 * and numdirtybuffers is now reasonable, wake them up. 168 */ 169 170static __inline void 171numdirtywakeup(void) 172{ 173 if (numdirtybuffers < hidirtybuffers) { 174 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) { 175 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH; 176 wakeup(&needsbuffer); 177 } 178 } 179} 180 181/* 182 * bufspacewakeup: 183 * 184 * Called when buffer space is potentially available for recovery. 185 * getnewbuf() will block on this flag when it is unable to free 186 * sufficient buffer space. Buffer space becomes recoverable when 187 * bp's get placed back in the queues. 188 */ 189 190static __inline void 191bufspacewakeup(void) 192{ 193 /* 194 * If someone is waiting for BUF space, wake them up. Even 195 * though we haven't freed the kva space yet, the waiting 196 * process will be able to now. 197 */ 198 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) { 199 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE; 200 wakeup(&needsbuffer); 201 } 202} 203 204/* 205 * bufcountwakeup: 206 * 207 * Called when a buffer has been added to one of the free queues to 208 * account for the buffer and to wakeup anyone waiting for free buffers. 209 * This typically occurs when large amounts of metadata are being handled 210 * by the buffer cache ( else buffer space runs out first, usually ). 211 */ 212 213static __inline void 214bufcountwakeup(void) 215{ 216 ++numfreebuffers; 217 if (needsbuffer) { 218 needsbuffer &= ~VFS_BIO_NEED_ANY; 219 if (numfreebuffers >= hifreebuffers) 220 needsbuffer &= ~VFS_BIO_NEED_FREE; 221 wakeup(&needsbuffer); 222 } 223} 224 225/* 226 * vfs_buf_test_cache: 227 * 228 * Called when a buffer is extended. This function clears the B_CACHE 229 * bit if the newly extended portion of the buffer does not contain 230 * valid data. 231 */ 232static __inline__ 233void 234vfs_buf_test_cache(struct buf *bp, 235 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 236 vm_page_t m) 237{ 238 if (bp->b_flags & B_CACHE) { 239 int base = (foff + off) & PAGE_MASK; 240 if (vm_page_is_valid(m, base, size) == 0) 241 bp->b_flags &= ~B_CACHE; 242 } 243} 244 245static __inline__ 246void 247bd_wakeup(int dirtybuflevel) 248{ 249 if (numdirtybuffers >= dirtybuflevel && bd_request == 0) { 250 bd_request = 1; 251 wakeup(&bd_request); 252 } 253} 254 255/* 256 * bd_speedup - speedup the buffer cache flushing code 257 */ 258 259static __inline__ 260void 261bd_speedup(void) 262{ 263 bd_wakeup(1); 264} 265 266/* 267 * Initialize buffer headers and related structures. 268 */ 269 270caddr_t 271bufhashinit(caddr_t vaddr) 272{ 273 /* first, make a null hash table */ 274 for (bufhashmask = 8; bufhashmask < nbuf / 4; bufhashmask <<= 1) 275 ; 276 bufhashtbl = (void *)vaddr; 277 vaddr = vaddr + sizeof(*bufhashtbl) * bufhashmask; 278 --bufhashmask; 279 return(vaddr); 280} 281 282void 283bufinit(void) 284{ 285 struct buf *bp; 286 int i; 287 288 TAILQ_INIT(&bswlist); 289 LIST_INIT(&invalhash); 290 simple_lock_init(&buftimelock); 291 292 for (i = 0; i <= bufhashmask; i++) 293 LIST_INIT(&bufhashtbl[i]); 294 295 /* next, make a null set of free lists */ 296 for (i = 0; i < BUFFER_QUEUES; i++) 297 TAILQ_INIT(&bufqueues[i]); 298 299 /* finally, initialize each buffer header and stick on empty q */ 300 for (i = 0; i < nbuf; i++) { 301 bp = &buf[i]; 302 bzero(bp, sizeof *bp); 303 bp->b_flags = B_INVAL; /* we're just an empty header */ 304 bp->b_dev = NODEV; 305 bp->b_rcred = NOCRED; 306 bp->b_wcred = NOCRED; 307 bp->b_qindex = QUEUE_EMPTY; 308 bp->b_xflags = 0; 309 LIST_INIT(&bp->b_dep); 310 BUF_LOCKINIT(bp); 311 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 312 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 313 } 314 315 /* 316 * maxbufspace is the absolute maximum amount of buffer space we are 317 * allowed to reserve in KVM and in real terms. The absolute maximum 318 * is nominally used by buf_daemon. hibufspace is the nominal maximum 319 * used by most other processes. The differential is required to 320 * ensure that buf_daemon is able to run when other processes might 321 * be blocked waiting for buffer space. 322 * 323 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 324 * this may result in KVM fragmentation which is not handled optimally 325 * by the system. 326 */ 327 maxbufspace = nbuf * BKVASIZE; 328 hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 329 lobufspace = hibufspace - MAXBSIZE; 330 331/* 332 * Limit the amount of malloc memory since it is wired permanently into 333 * the kernel space. Even though this is accounted for in the buffer 334 * allocation, we don't want the malloced region to grow uncontrolled. 335 * The malloc scheme improves memory utilization significantly on average 336 * (small) directories. 337 */ 338 maxbufmallocspace = hibufspace / 20; 339 340/* 341 * Reduce the chance of a deadlock occuring by limiting the number 342 * of delayed-write dirty buffers we allow to stack up. 343 */ 344 hidirtybuffers = nbuf / 4 + 20; 345 numdirtybuffers = 0; 346/* 347 * To support extreme low-memory systems, make sure hidirtybuffers cannot 348 * eat up all available buffer space. This occurs when our minimum cannot 349 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 350 * BKVASIZE'd (8K) buffers. 351 */ 352 while (hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 353 hidirtybuffers >>= 1; 354 } 355 356/* 357 * Try to keep the number of free buffers in the specified range, 358 * and give special processes (e.g. like buf_daemon) access to an 359 * emergency reserve. 360 */ 361 lofreebuffers = nbuf / 18 + 5; 362 hifreebuffers = 2 * lofreebuffers; 363 numfreebuffers = nbuf; 364 365/* 366 * Maximum number of async ops initiated per buf_daemon loop. This is 367 * somewhat of a hack at the moment, we really need to limit ourselves 368 * based on the number of bytes of I/O in-transit that were initiated 369 * from buf_daemon. 370 */ 371 if ((maxbdrun = nswbuf / 4) < 4) 372 maxbdrun = 4; 373 374 bogus_offset = kmem_alloc_pageable(kernel_map, PAGE_SIZE); 375 bogus_page = vm_page_alloc(kernel_object, 376 ((bogus_offset - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 377 VM_ALLOC_NORMAL); 378 cnt.v_wire_count++; 379 380} 381 382/* 383 * bfreekva() - free the kva allocation for a buffer. 384 * 385 * Must be called at splbio() or higher as this is the only locking for 386 * buffer_map. 387 * 388 * Since this call frees up buffer space, we call bufspacewakeup(). 389 */ 390static void 391bfreekva(struct buf * bp) 392{ 393 if (bp->b_kvasize) { 394 ++buffreekvacnt; 395 bufspace -= bp->b_kvasize; 396 vm_map_delete(buffer_map, 397 (vm_offset_t) bp->b_kvabase, 398 (vm_offset_t) bp->b_kvabase + bp->b_kvasize 399 ); 400 bp->b_kvasize = 0; 401 bufspacewakeup(); 402 } 403} 404 405/* 406 * bremfree: 407 * 408 * Remove the buffer from the appropriate free list. 409 */ 410void 411bremfree(struct buf * bp) 412{ 413 int s = splbio(); 414 int old_qindex = bp->b_qindex; 415 416 if (bp->b_qindex != QUEUE_NONE) { 417 KASSERT(BUF_REFCNT(bp) == 1, ("bremfree: bp %p not locked",bp)); 418 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 419 bp->b_qindex = QUEUE_NONE; 420 runningbufspace += bp->b_bufsize; 421 } else { 422 if (BUF_REFCNT(bp) <= 1) 423 panic("bremfree: removing a buffer not on a queue"); 424 } 425 426 /* 427 * Fixup numfreebuffers count. If the buffer is invalid or not 428 * delayed-write, and it was on the EMPTY, LRU, or AGE queues, 429 * the buffer was free and we must decrement numfreebuffers. 430 */ 431 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { 432 switch(old_qindex) { 433 case QUEUE_DIRTY: 434 case QUEUE_CLEAN: 435 case QUEUE_EMPTY: 436 case QUEUE_EMPTYKVA: 437 --numfreebuffers; 438 break; 439 default: 440 break; 441 } 442 } 443 splx(s); 444} 445 446 447/* 448 * Get a buffer with the specified data. Look in the cache first. We 449 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 450 * is set, the buffer is valid and we do not have to do anything ( see 451 * getblk() ). 452 */ 453int 454bread(struct vnode * vp, daddr_t blkno, int size, struct ucred * cred, 455 struct buf ** bpp) 456{ 457 struct buf *bp; 458 459 bp = getblk(vp, blkno, size, 0, 0); 460 *bpp = bp; 461 462 /* if not found in cache, do some I/O */ 463 if ((bp->b_flags & B_CACHE) == 0) { 464 if (curproc != NULL) 465 curproc->p_stats->p_ru.ru_inblock++; 466 KASSERT(!(bp->b_flags & B_ASYNC), ("bread: illegal async bp %p", bp)); 467 bp->b_iocmd = BIO_READ; 468 bp->b_flags &= ~B_INVAL; 469 bp->b_ioflags &= ~BIO_ERROR; 470 if (bp->b_rcred == NOCRED) { 471 if (cred != NOCRED) 472 crhold(cred); 473 bp->b_rcred = cred; 474 } 475 vfs_busy_pages(bp, 0); 476 VOP_STRATEGY(vp, bp); 477 return (bufwait(bp)); 478 } 479 return (0); 480} 481 482/* 483 * Operates like bread, but also starts asynchronous I/O on 484 * read-ahead blocks. We must clear BIO_ERROR and B_INVAL prior 485 * to initiating I/O . If B_CACHE is set, the buffer is valid 486 * and we do not have to do anything. 487 */ 488int 489breadn(struct vnode * vp, daddr_t blkno, int size, 490 daddr_t * rablkno, int *rabsize, 491 int cnt, struct ucred * cred, struct buf ** bpp) 492{ 493 struct buf *bp, *rabp; 494 int i; 495 int rv = 0, readwait = 0; 496 497 *bpp = bp = getblk(vp, blkno, size, 0, 0); 498 499 /* if not found in cache, do some I/O */ 500 if ((bp->b_flags & B_CACHE) == 0) { 501 if (curproc != NULL) 502 curproc->p_stats->p_ru.ru_inblock++; 503 bp->b_iocmd = BIO_READ; 504 bp->b_flags &= ~B_INVAL; 505 bp->b_ioflags &= ~BIO_ERROR; 506 if (bp->b_rcred == NOCRED) { 507 if (cred != NOCRED) 508 crhold(cred); 509 bp->b_rcred = cred; 510 } 511 vfs_busy_pages(bp, 0); 512 VOP_STRATEGY(vp, bp); 513 ++readwait; 514 } 515 516 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 517 if (inmem(vp, *rablkno)) 518 continue; 519 rabp = getblk(vp, *rablkno, *rabsize, 0, 0); 520 521 if ((rabp->b_flags & B_CACHE) == 0) { 522 if (curproc != NULL) 523 curproc->p_stats->p_ru.ru_inblock++; 524 rabp->b_flags |= B_ASYNC; 525 rabp->b_flags &= ~B_INVAL; 526 rabp->b_ioflags &= ~BIO_ERROR; 527 rabp->b_iocmd = BIO_READ; 528 if (rabp->b_rcred == NOCRED) { 529 if (cred != NOCRED) 530 crhold(cred); 531 rabp->b_rcred = cred; 532 } 533 vfs_busy_pages(rabp, 0); 534 BUF_KERNPROC(rabp); 535 VOP_STRATEGY(vp, rabp); 536 } else { 537 brelse(rabp); 538 } 539 } 540 541 if (readwait) { 542 rv = bufwait(bp); 543 } 544 return (rv); 545} 546 547/* 548 * Write, release buffer on completion. (Done by iodone 549 * if async). Do not bother writing anything if the buffer 550 * is invalid. 551 * 552 * Note that we set B_CACHE here, indicating that buffer is 553 * fully valid and thus cacheable. This is true even of NFS 554 * now so we set it generally. This could be set either here 555 * or in biodone() since the I/O is synchronous. We put it 556 * here. 557 */ 558int 559bwrite(struct buf * bp) 560{ 561 int oldflags, s; 562 struct buf *newbp; 563 564 if (bp->b_flags & B_INVAL) { 565 brelse(bp); 566 return (0); 567 } 568 569 oldflags = bp->b_flags; 570 571 if (BUF_REFCNT(bp) == 0) 572 panic("bwrite: buffer is not busy???"); 573 s = splbio(); 574 /* 575 * If a background write is already in progress, delay 576 * writing this block if it is asynchronous. Otherwise 577 * wait for the background write to complete. 578 */ 579 if (bp->b_xflags & BX_BKGRDINPROG) { 580 if (bp->b_flags & B_ASYNC) { 581 splx(s); 582 bdwrite(bp); 583 return (0); 584 } 585 bp->b_xflags |= BX_BKGRDWAIT; 586 tsleep(&bp->b_xflags, PRIBIO, "biord", 0); 587 if (bp->b_xflags & BX_BKGRDINPROG) 588 panic("bwrite: still writing"); 589 } 590 591 /* Mark the buffer clean */ 592 bundirty(bp); 593 594 /* 595 * If this buffer is marked for background writing and we 596 * do not have to wait for it, make a copy and write the 597 * copy so as to leave this buffer ready for further use. 598 */ 599 if ((bp->b_xflags & BX_BKGRDWRITE) && (bp->b_flags & B_ASYNC)) { 600 if (bp->b_iodone != NULL) { 601 printf("bp->b_iodone = %p\n", bp->b_iodone); 602 panic("bwrite: need chained iodone"); 603 } 604 605 /* get a new block */ 606 newbp = geteblk(bp->b_bufsize); 607 608 /* set it to be identical to the old block */ 609 memcpy(newbp->b_data, bp->b_data, bp->b_bufsize); 610 bgetvp(bp->b_vp, newbp); 611 newbp->b_lblkno = bp->b_lblkno; 612 newbp->b_blkno = bp->b_blkno; 613 newbp->b_offset = bp->b_offset; 614 newbp->b_iodone = vfs_backgroundwritedone; 615 newbp->b_flags |= B_ASYNC; 616 newbp->b_flags &= ~B_INVAL; 617 618 /* move over the dependencies */ 619 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_movedeps) 620 (*bioops.io_movedeps)(bp, newbp); 621 622 /* 623 * Initiate write on the copy, release the original to 624 * the B_LOCKED queue so that it cannot go away until 625 * the background write completes. If not locked it could go 626 * away and then be reconstituted while it was being written. 627 * If the reconstituted buffer were written, we could end up 628 * with two background copies being written at the same time. 629 */ 630 bp->b_xflags |= BX_BKGRDINPROG; 631 bp->b_flags |= B_LOCKED; 632 bqrelse(bp); 633 bp = newbp; 634 } 635 636 bp->b_flags &= ~B_DONE; 637 bp->b_ioflags &= ~BIO_ERROR; 638 bp->b_flags |= B_WRITEINPROG | B_CACHE; 639 bp->b_iocmd = BIO_WRITE; 640 641 bp->b_vp->v_numoutput++; 642 vfs_busy_pages(bp, 1); 643 if (curproc != NULL) 644 curproc->p_stats->p_ru.ru_oublock++; 645 splx(s); 646 if (oldflags & B_ASYNC) 647 BUF_KERNPROC(bp); 648 BUF_STRATEGY(bp); 649 650 if ((oldflags & B_ASYNC) == 0) { 651 int rtval = bufwait(bp); 652 brelse(bp); 653 return (rtval); 654 } 655 656 return (0); 657} 658 659/* 660 * Complete a background write started from bwrite. 661 */ 662static void 663vfs_backgroundwritedone(bp) 664 struct buf *bp; 665{ 666 struct buf *origbp; 667 668 /* 669 * Find the original buffer that we are writing. 670 */ 671 if ((origbp = gbincore(bp->b_vp, bp->b_lblkno)) == NULL) 672 panic("backgroundwritedone: lost buffer"); 673 /* 674 * Process dependencies then return any unfinished ones. 675 */ 676 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_complete) 677 (*bioops.io_complete)(bp); 678 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_movedeps) 679 (*bioops.io_movedeps)(bp, origbp); 680 /* 681 * Clear the BX_BKGRDINPROG flag in the original buffer 682 * and awaken it if it is waiting for the write to complete. 683 */ 684 origbp->b_xflags &= ~BX_BKGRDINPROG; 685 if (origbp->b_xflags & BX_BKGRDWAIT) { 686 origbp->b_xflags &= ~BX_BKGRDWAIT; 687 wakeup(&origbp->b_xflags); 688 } 689 /* 690 * Clear the B_LOCKED flag and remove it from the locked 691 * queue if it currently resides there. 692 */ 693 origbp->b_flags &= ~B_LOCKED; 694 if (BUF_LOCK(origbp, LK_EXCLUSIVE | LK_NOWAIT) == 0) { 695 bremfree(origbp); 696 bqrelse(origbp); 697 } 698 /* 699 * This buffer is marked B_NOCACHE, so when it is released 700 * by biodone, it will be tossed. We mark it with BIO_READ 701 * to avoid biodone doing a second vwakeup. 702 */ 703 bp->b_flags |= B_NOCACHE; 704 bp->b_iocmd = BIO_READ; 705 bp->b_flags &= ~(B_CACHE | B_DONE); 706 bp->b_iodone = 0; 707 bufdone(bp); 708} 709 710/* 711 * Delayed write. (Buffer is marked dirty). Do not bother writing 712 * anything if the buffer is marked invalid. 713 * 714 * Note that since the buffer must be completely valid, we can safely 715 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 716 * biodone() in order to prevent getblk from writing the buffer 717 * out synchronously. 718 */ 719void 720bdwrite(struct buf * bp) 721{ 722 if (BUF_REFCNT(bp) == 0) 723 panic("bdwrite: buffer is not busy"); 724 725 if (bp->b_flags & B_INVAL) { 726 brelse(bp); 727 return; 728 } 729 bdirty(bp); 730 731 /* 732 * Set B_CACHE, indicating that the buffer is fully valid. This is 733 * true even of NFS now. 734 */ 735 bp->b_flags |= B_CACHE; 736 737 /* 738 * This bmap keeps the system from needing to do the bmap later, 739 * perhaps when the system is attempting to do a sync. Since it 740 * is likely that the indirect block -- or whatever other datastructure 741 * that the filesystem needs is still in memory now, it is a good 742 * thing to do this. Note also, that if the pageout daemon is 743 * requesting a sync -- there might not be enough memory to do 744 * the bmap then... So, this is important to do. 745 */ 746 if (bp->b_lblkno == bp->b_blkno) { 747 VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 748 } 749 750 /* 751 * Set the *dirty* buffer range based upon the VM system dirty pages. 752 */ 753 vfs_setdirty(bp); 754 755 /* 756 * We need to do this here to satisfy the vnode_pager and the 757 * pageout daemon, so that it thinks that the pages have been 758 * "cleaned". Note that since the pages are in a delayed write 759 * buffer -- the VFS layer "will" see that the pages get written 760 * out on the next sync, or perhaps the cluster will be completed. 761 */ 762 vfs_clean_pages(bp); 763 bqrelse(bp); 764 765 /* 766 * Wakeup the buffer flushing daemon if we have saturated the 767 * buffer cache. 768 */ 769 770 bd_wakeup(hidirtybuffers); 771 772 /* 773 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 774 * due to the softdep code. 775 */ 776} 777 778/* 779 * bdirty: 780 * 781 * Turn buffer into delayed write request. We must clear BIO_READ and 782 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 783 * itself to properly update it in the dirty/clean lists. We mark it 784 * B_DONE to ensure that any asynchronization of the buffer properly 785 * clears B_DONE ( else a panic will occur later ). 786 * 787 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 788 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 789 * should only be called if the buffer is known-good. 790 * 791 * Since the buffer is not on a queue, we do not update the numfreebuffers 792 * count. 793 * 794 * Must be called at splbio(). 795 * The buffer must be on QUEUE_NONE. 796 */ 797void 798bdirty(bp) 799 struct buf *bp; 800{ 801 KASSERT(bp->b_qindex == QUEUE_NONE, ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 802 bp->b_flags &= ~(B_RELBUF); 803 bp->b_iocmd = BIO_WRITE; 804 805 if ((bp->b_flags & B_DELWRI) == 0) { 806 bp->b_flags |= B_DONE | B_DELWRI; 807 reassignbuf(bp, bp->b_vp); 808 ++numdirtybuffers; 809 bd_wakeup(hidirtybuffers); 810 } 811} 812 813/* 814 * bundirty: 815 * 816 * Clear B_DELWRI for buffer. 817 * 818 * Since the buffer is not on a queue, we do not update the numfreebuffers 819 * count. 820 * 821 * Must be called at splbio(). 822 * The buffer must be on QUEUE_NONE. 823 */ 824 825void 826bundirty(bp) 827 struct buf *bp; 828{ 829 KASSERT(bp->b_qindex == QUEUE_NONE, ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 830 831 if (bp->b_flags & B_DELWRI) { 832 bp->b_flags &= ~B_DELWRI; 833 reassignbuf(bp, bp->b_vp); 834 --numdirtybuffers; 835 numdirtywakeup(); 836 } 837 /* 838 * Since it is now being written, we can clear its deferred write flag. 839 */ 840 bp->b_flags &= ~B_DEFERRED; 841} 842 843/* 844 * bawrite: 845 * 846 * Asynchronous write. Start output on a buffer, but do not wait for 847 * it to complete. The buffer is released when the output completes. 848 * 849 * bwrite() ( or the VOP routine anyway ) is responsible for handling 850 * B_INVAL buffers. Not us. 851 */ 852void 853bawrite(struct buf * bp) 854{ 855 bp->b_flags |= B_ASYNC; 856 (void) BUF_WRITE(bp); 857} 858 859/* 860 * bowrite: 861 * 862 * Ordered write. Start output on a buffer, and flag it so that the 863 * device will write it in the order it was queued. The buffer is 864 * released when the output completes. bwrite() ( or the VOP routine 865 * anyway ) is responsible for handling B_INVAL buffers. 866 */ 867int 868bowrite(struct buf * bp) 869{ 870 bp->b_ioflags |= BIO_ORDERED; 871 bp->b_flags |= B_ASYNC; 872 return (BUF_WRITE(bp)); 873} 874 875/* 876 * bwillwrite: 877 * 878 * Called prior to the locking of any vnodes when we are expecting to 879 * write. We do not want to starve the buffer cache with too many 880 * dirty buffers so we block here. By blocking prior to the locking 881 * of any vnodes we attempt to avoid the situation where a locked vnode 882 * prevents the various system daemons from flushing related buffers. 883 */ 884 885void 886bwillwrite(void) 887{ 888 int slop = hidirtybuffers / 10; 889 890 if (numdirtybuffers > hidirtybuffers + slop) { 891 int s; 892 893 s = splbio(); 894 while (numdirtybuffers > hidirtybuffers) { 895 bd_wakeup(hidirtybuffers); 896 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH; 897 tsleep(&needsbuffer, (PRIBIO + 4), "flswai", 0); 898 } 899 splx(s); 900 } 901} 902 903/* 904 * brelse: 905 * 906 * Release a busy buffer and, if requested, free its resources. The 907 * buffer will be stashed in the appropriate bufqueue[] allowing it 908 * to be accessed later as a cache entity or reused for other purposes. 909 */ 910void 911brelse(struct buf * bp) 912{ 913 int s; 914 915 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 916 917 s = splbio(); 918 919 if (bp->b_flags & B_LOCKED) 920 bp->b_ioflags &= ~BIO_ERROR; 921 922 if (bp->b_iocmd == BIO_WRITE && 923 (bp->b_ioflags & BIO_ERROR) && 924 !(bp->b_flags & B_INVAL)) { 925 /* 926 * Failed write, redirty. Must clear BIO_ERROR to prevent 927 * pages from being scrapped. If B_INVAL is set then 928 * this case is not run and the next case is run to 929 * destroy the buffer. B_INVAL can occur if the buffer 930 * is outside the range supported by the underlying device. 931 */ 932 bp->b_ioflags &= ~BIO_ERROR; 933 bdirty(bp); 934 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 935 (bp->b_ioflags & BIO_ERROR) || 936 bp->b_iocmd == BIO_DELETE || (bp->b_bufsize <= 0)) { 937 /* 938 * Either a failed I/O or we were asked to free or not 939 * cache the buffer. 940 */ 941 bp->b_flags |= B_INVAL; 942 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_deallocate) 943 (*bioops.io_deallocate)(bp); 944 if (bp->b_flags & B_DELWRI) { 945 --numdirtybuffers; 946 numdirtywakeup(); 947 } 948 bp->b_flags &= ~(B_DELWRI | B_CACHE); 949 if ((bp->b_flags & B_VMIO) == 0) { 950 if (bp->b_bufsize) 951 allocbuf(bp, 0); 952 if (bp->b_vp) 953 brelvp(bp); 954 } 955 } 956 957 /* 958 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 959 * is called with B_DELWRI set, the underlying pages may wind up 960 * getting freed causing a previous write (bdwrite()) to get 'lost' 961 * because pages associated with a B_DELWRI bp are marked clean. 962 * 963 * We still allow the B_INVAL case to call vfs_vmio_release(), even 964 * if B_DELWRI is set. 965 */ 966 967 if (bp->b_flags & B_DELWRI) 968 bp->b_flags &= ~B_RELBUF; 969 970 /* 971 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 972 * constituted, not even NFS buffers now. Two flags effect this. If 973 * B_INVAL, the struct buf is invalidated but the VM object is kept 974 * around ( i.e. so it is trivial to reconstitute the buffer later ). 975 * 976 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 977 * invalidated. BIO_ERROR cannot be set for a failed write unless the 978 * buffer is also B_INVAL because it hits the re-dirtying code above. 979 * 980 * Normally we can do this whether a buffer is B_DELWRI or not. If 981 * the buffer is an NFS buffer, it is tracking piecemeal writes or 982 * the commit state and we cannot afford to lose the buffer. If the 983 * buffer has a background write in progress, we need to keep it 984 * around to prevent it from being reconstituted and starting a second 985 * background write. 986 */ 987 if ((bp->b_flags & B_VMIO) 988 && !(bp->b_vp->v_tag == VT_NFS && 989 !vn_isdisk(bp->b_vp, NULL) && 990 (bp->b_flags & B_DELWRI) && 991 (bp->b_xflags & BX_BKGRDINPROG)) 992 ) { 993 994 int i, j, resid; 995 vm_page_t m; 996 off_t foff; 997 vm_pindex_t poff; 998 vm_object_t obj; 999 struct vnode *vp; 1000 1001 vp = bp->b_vp; 1002 1003 /* 1004 * Get the base offset and length of the buffer. Note that 1005 * for block sizes that are less then PAGE_SIZE, the b_data 1006 * base of the buffer does not represent exactly b_offset and 1007 * neither b_offset nor b_size are necessarily page aligned. 1008 * Instead, the starting position of b_offset is: 1009 * 1010 * b_data + (b_offset & PAGE_MASK) 1011 * 1012 * block sizes less then DEV_BSIZE (usually 512) are not 1013 * supported due to the page granularity bits (m->valid, 1014 * m->dirty, etc...). 1015 * 1016 * See man buf(9) for more information 1017 */ 1018 1019 resid = bp->b_bufsize; 1020 foff = bp->b_offset; 1021 1022 for (i = 0; i < bp->b_npages; i++) { 1023 m = bp->b_pages[i]; 1024 vm_page_flag_clear(m, PG_ZERO); 1025 if (m == bogus_page) { 1026 1027 obj = (vm_object_t) vp->v_object; 1028 poff = OFF_TO_IDX(bp->b_offset); 1029 1030 for (j = i; j < bp->b_npages; j++) { 1031 m = bp->b_pages[j]; 1032 if (m == bogus_page) { 1033 m = vm_page_lookup(obj, poff + j); 1034 if (!m) { 1035 panic("brelse: page missing\n"); 1036 } 1037 bp->b_pages[j] = m; 1038 } 1039 } 1040 1041 if ((bp->b_flags & B_INVAL) == 0) { 1042 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 1043 } 1044 } 1045 if ((bp->b_flags & B_NOCACHE) || (bp->b_ioflags & BIO_ERROR)) { 1046 int poffset = foff & PAGE_MASK; 1047 int presid = resid > (PAGE_SIZE - poffset) ? 1048 (PAGE_SIZE - poffset) : resid; 1049 1050 KASSERT(presid >= 0, ("brelse: extra page")); 1051 vm_page_set_invalid(m, poffset, presid); 1052 } 1053 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1054 foff = (foff + PAGE_SIZE) & ~PAGE_MASK; 1055 } 1056 1057 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1058 vfs_vmio_release(bp); 1059 1060 } else if (bp->b_flags & B_VMIO) { 1061 1062 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1063 vfs_vmio_release(bp); 1064 1065 } 1066 1067 if (bp->b_qindex != QUEUE_NONE) 1068 panic("brelse: free buffer onto another queue???"); 1069 if (BUF_REFCNT(bp) > 1) { 1070 /* Temporary panic to verify exclusive locking */ 1071 /* This panic goes away when we allow shared refs */ 1072 panic("brelse: multiple refs"); 1073 /* do not release to free list */ 1074 BUF_UNLOCK(bp); 1075 splx(s); 1076 return; 1077 } 1078 1079 /* enqueue */ 1080 1081 /* buffers with no memory */ 1082 if (bp->b_bufsize == 0) { 1083 bp->b_flags |= B_INVAL; 1084 bp->b_xflags &= ~BX_BKGRDWRITE; 1085 if (bp->b_xflags & BX_BKGRDINPROG) 1086 panic("losing buffer 1"); 1087 if (bp->b_kvasize) { 1088 bp->b_qindex = QUEUE_EMPTYKVA; 1089 } else { 1090 bp->b_qindex = QUEUE_EMPTY; 1091 } 1092 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1093 LIST_REMOVE(bp, b_hash); 1094 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1095 bp->b_dev = NODEV; 1096 /* buffers with junk contents */ 1097 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || (bp->b_ioflags & BIO_ERROR)) { 1098 bp->b_flags |= B_INVAL; 1099 bp->b_xflags &= ~BX_BKGRDWRITE; 1100 if (bp->b_xflags & BX_BKGRDINPROG) 1101 panic("losing buffer 2"); 1102 bp->b_qindex = QUEUE_CLEAN; 1103 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1104 LIST_REMOVE(bp, b_hash); 1105 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1106 bp->b_dev = NODEV; 1107 1108 /* buffers that are locked */ 1109 } else if (bp->b_flags & B_LOCKED) { 1110 bp->b_qindex = QUEUE_LOCKED; 1111 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LOCKED], bp, b_freelist); 1112 1113 /* remaining buffers */ 1114 } else { 1115 switch(bp->b_flags & (B_DELWRI|B_AGE)) { 1116 case B_DELWRI | B_AGE: 1117 bp->b_qindex = QUEUE_DIRTY; 1118 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_DIRTY], bp, b_freelist); 1119 break; 1120 case B_DELWRI: 1121 bp->b_qindex = QUEUE_DIRTY; 1122 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist); 1123 break; 1124 case B_AGE: 1125 bp->b_qindex = QUEUE_CLEAN; 1126 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1127 break; 1128 default: 1129 bp->b_qindex = QUEUE_CLEAN; 1130 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1131 break; 1132 } 1133 } 1134 1135 /* 1136 * If B_INVAL, clear B_DELWRI. We've already placed the buffer 1137 * on the correct queue. 1138 */ 1139 if ((bp->b_flags & (B_INVAL|B_DELWRI)) == (B_INVAL|B_DELWRI)) { 1140 bp->b_flags &= ~B_DELWRI; 1141 --numdirtybuffers; 1142 numdirtywakeup(); 1143 } 1144 1145 runningbufspace -= bp->b_bufsize; 1146 1147 /* 1148 * Fixup numfreebuffers count. The bp is on an appropriate queue 1149 * unless locked. We then bump numfreebuffers if it is not B_DELWRI. 1150 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1151 * if B_INVAL is set ). 1152 */ 1153 1154 if ((bp->b_flags & B_LOCKED) == 0 && !(bp->b_flags & B_DELWRI)) 1155 bufcountwakeup(); 1156 1157 /* 1158 * Something we can maybe free. 1159 */ 1160 1161 if (bp->b_bufsize || bp->b_kvasize) 1162 bufspacewakeup(); 1163 1164 /* unlock */ 1165 BUF_UNLOCK(bp); 1166 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1167 bp->b_ioflags &= ~BIO_ORDERED; 1168 splx(s); 1169} 1170 1171/* 1172 * Release a buffer back to the appropriate queue but do not try to free 1173 * it. 1174 * 1175 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1176 * biodone() to requeue an async I/O on completion. It is also used when 1177 * known good buffers need to be requeued but we think we may need the data 1178 * again soon. 1179 */ 1180void 1181bqrelse(struct buf * bp) 1182{ 1183 int s; 1184 1185 s = splbio(); 1186 1187 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1188 1189 if (bp->b_qindex != QUEUE_NONE) 1190 panic("bqrelse: free buffer onto another queue???"); 1191 if (BUF_REFCNT(bp) > 1) { 1192 /* do not release to free list */ 1193 panic("bqrelse: multiple refs"); 1194 BUF_UNLOCK(bp); 1195 splx(s); 1196 return; 1197 } 1198 if (bp->b_flags & B_LOCKED) { 1199 bp->b_ioflags &= ~BIO_ERROR; 1200 bp->b_qindex = QUEUE_LOCKED; 1201 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LOCKED], bp, b_freelist); 1202 /* buffers with stale but valid contents */ 1203 } else if (bp->b_flags & B_DELWRI) { 1204 bp->b_qindex = QUEUE_DIRTY; 1205 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist); 1206 } else { 1207 bp->b_qindex = QUEUE_CLEAN; 1208 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1209 } 1210 1211 runningbufspace -= bp->b_bufsize; 1212 1213 if ((bp->b_flags & B_LOCKED) == 0 && 1214 ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI))) { 1215 bufcountwakeup(); 1216 } 1217 1218 /* 1219 * Something we can maybe wakeup 1220 */ 1221 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1222 bufspacewakeup(); 1223 1224 /* unlock */ 1225 BUF_UNLOCK(bp); 1226 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1227 bp->b_ioflags &= ~BIO_ORDERED; 1228 splx(s); 1229} 1230 1231static void 1232vfs_vmio_release(bp) 1233 struct buf *bp; 1234{ 1235 int i, s; 1236 vm_page_t m; 1237 1238 s = splvm(); 1239 for (i = 0; i < bp->b_npages; i++) { 1240 m = bp->b_pages[i]; 1241 bp->b_pages[i] = NULL; 1242 /* 1243 * In order to keep page LRU ordering consistent, put 1244 * everything on the inactive queue. 1245 */ 1246 vm_page_unwire(m, 0); 1247 /* 1248 * We don't mess with busy pages, it is 1249 * the responsibility of the process that 1250 * busied the pages to deal with them. 1251 */ 1252 if ((m->flags & PG_BUSY) || (m->busy != 0)) 1253 continue; 1254 1255 if (m->wire_count == 0) { 1256 vm_page_flag_clear(m, PG_ZERO); 1257 /* 1258 * Might as well free the page if we can and it has 1259 * no valid data. 1260 */ 1261 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && m->hold_count == 0) { 1262 vm_page_busy(m); 1263 vm_page_protect(m, VM_PROT_NONE); 1264 vm_page_free(m); 1265 } 1266 } 1267 } 1268 runningbufspace -= bp->b_bufsize; 1269 splx(s); 1270 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages); 1271 if (bp->b_bufsize) 1272 bufspacewakeup(); 1273 bp->b_npages = 0; 1274 bp->b_bufsize = 0; 1275 bp->b_flags &= ~B_VMIO; 1276 if (bp->b_vp) 1277 brelvp(bp); 1278} 1279 1280/* 1281 * Check to see if a block is currently memory resident. 1282 */ 1283struct buf * 1284gbincore(struct vnode * vp, daddr_t blkno) 1285{ 1286 struct buf *bp; 1287 struct bufhashhdr *bh; 1288 1289 bh = bufhash(vp, blkno); 1290 1291 /* Search hash chain */ 1292 LIST_FOREACH(bp, bh, b_hash) { 1293 /* hit */ 1294 if (bp->b_vp == vp && bp->b_lblkno == blkno && 1295 (bp->b_flags & B_INVAL) == 0) { 1296 break; 1297 } 1298 } 1299 return (bp); 1300} 1301 1302/* 1303 * vfs_bio_awrite: 1304 * 1305 * Implement clustered async writes for clearing out B_DELWRI buffers. 1306 * This is much better then the old way of writing only one buffer at 1307 * a time. Note that we may not be presented with the buffers in the 1308 * correct order, so we search for the cluster in both directions. 1309 */ 1310int 1311vfs_bio_awrite(struct buf * bp) 1312{ 1313 int i; 1314 int j; 1315 daddr_t lblkno = bp->b_lblkno; 1316 struct vnode *vp = bp->b_vp; 1317 int s; 1318 int ncl; 1319 struct buf *bpa; 1320 int nwritten; 1321 int size; 1322 int maxcl; 1323 1324 s = splbio(); 1325 /* 1326 * right now we support clustered writing only to regular files. If 1327 * we find a clusterable block we could be in the middle of a cluster 1328 * rather then at the beginning. 1329 */ 1330 if ((vp->v_type == VREG) && 1331 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1332 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1333 1334 size = vp->v_mount->mnt_stat.f_iosize; 1335 maxcl = MAXPHYS / size; 1336 1337 for (i = 1; i < maxcl; i++) { 1338 if ((bpa = gbincore(vp, lblkno + i)) && 1339 BUF_REFCNT(bpa) == 0 && 1340 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == 1341 (B_DELWRI | B_CLUSTEROK)) && 1342 (bpa->b_bufsize == size)) { 1343 if ((bpa->b_blkno == bpa->b_lblkno) || 1344 (bpa->b_blkno != 1345 bp->b_blkno + ((i * size) >> DEV_BSHIFT))) 1346 break; 1347 } else { 1348 break; 1349 } 1350 } 1351 for (j = 1; i + j <= maxcl && j <= lblkno; j++) { 1352 if ((bpa = gbincore(vp, lblkno - j)) && 1353 BUF_REFCNT(bpa) == 0 && 1354 ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == 1355 (B_DELWRI | B_CLUSTEROK)) && 1356 (bpa->b_bufsize == size)) { 1357 if ((bpa->b_blkno == bpa->b_lblkno) || 1358 (bpa->b_blkno != 1359 bp->b_blkno - ((j * size) >> DEV_BSHIFT))) 1360 break; 1361 } else { 1362 break; 1363 } 1364 } 1365 --j; 1366 ncl = i + j; 1367 /* 1368 * this is a possible cluster write 1369 */ 1370 if (ncl != 1) { 1371 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl); 1372 splx(s); 1373 return nwritten; 1374 } 1375 } 1376 1377 BUF_LOCK(bp, LK_EXCLUSIVE); 1378 bremfree(bp); 1379 bp->b_flags |= B_ASYNC; 1380 1381 splx(s); 1382 /* 1383 * default (old) behavior, writing out only one block 1384 * 1385 * XXX returns b_bufsize instead of b_bcount for nwritten? 1386 */ 1387 nwritten = bp->b_bufsize; 1388 (void) BUF_WRITE(bp); 1389 1390 return nwritten; 1391} 1392 1393/* 1394 * getnewbuf: 1395 * 1396 * Find and initialize a new buffer header, freeing up existing buffers 1397 * in the bufqueues as necessary. The new buffer is returned locked. 1398 * 1399 * Important: B_INVAL is not set. If the caller wishes to throw the 1400 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1401 * 1402 * We block if: 1403 * We have insufficient buffer headers 1404 * We have insufficient buffer space 1405 * buffer_map is too fragmented ( space reservation fails ) 1406 * If we have to flush dirty buffers ( but we try to avoid this ) 1407 * 1408 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1409 * Instead we ask the buf daemon to do it for us. We attempt to 1410 * avoid piecemeal wakeups of the pageout daemon. 1411 */ 1412 1413static struct buf * 1414getnewbuf(int slpflag, int slptimeo, int size, int maxsize) 1415{ 1416 struct buf *bp; 1417 struct buf *nbp; 1418 int defrag = 0; 1419 int nqindex; 1420 int isspecial; 1421 static int flushingbufs; 1422 1423 if (curproc && (curproc->p_flag & P_BUFEXHAUST) == 0) 1424 isspecial = 0; 1425 else 1426 isspecial = 1; 1427 1428 ++getnewbufcalls; 1429 --getnewbufrestarts; 1430restart: 1431 ++getnewbufrestarts; 1432 1433 /* 1434 * Setup for scan. If we do not have enough free buffers, 1435 * we setup a degenerate case that immediately fails. Note 1436 * that if we are specially marked process, we are allowed to 1437 * dip into our reserves. 1438 * 1439 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 1440 * 1441 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 1442 * However, there are a number of cases (defragging, reusing, ...) 1443 * where we cannot backup. 1444 */ 1445 1446 if (isspecial == 0 && numfreebuffers < lofreebuffers) { 1447 /* 1448 * This will cause an immediate failure 1449 */ 1450 nqindex = QUEUE_CLEAN; 1451 nbp = NULL; 1452 } else { 1453 /* 1454 * Locate a buffer which already has KVA assigned. First 1455 * try EMPTYKVA buffers. 1456 */ 1457 nqindex = QUEUE_EMPTYKVA; 1458 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 1459 1460 if (nbp == NULL) { 1461 /* 1462 * If no EMPTYKVA buffers and we are either 1463 * defragging or reusing, locate a CLEAN buffer 1464 * to free or reuse. If bufspace useage is low 1465 * skip this step so we can allocate a new buffer. 1466 */ 1467 if (defrag || bufspace >= lobufspace) { 1468 nqindex = QUEUE_CLEAN; 1469 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 1470 } 1471 1472 /* 1473 * Nada. If we are allowed to allocate an EMPTY 1474 * buffer, go get one. 1475 */ 1476 if (nbp == NULL && defrag == 0 && 1477 (isspecial || bufspace < hibufspace)) { 1478 nqindex = QUEUE_EMPTY; 1479 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1480 } 1481 } 1482 } 1483 1484 /* 1485 * Run scan, possibly freeing data and/or kva mappings on the fly 1486 * depending. 1487 */ 1488 1489 while ((bp = nbp) != NULL) { 1490 int qindex = nqindex; 1491 1492 /* 1493 * Calculate next bp ( we can only use it if we do not block 1494 * or do other fancy things ). 1495 */ 1496 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 1497 switch(qindex) { 1498 case QUEUE_EMPTY: 1499 nqindex = QUEUE_EMPTYKVA; 1500 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]))) 1501 break; 1502 /* fall through */ 1503 case QUEUE_EMPTYKVA: 1504 nqindex = QUEUE_CLEAN; 1505 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]))) 1506 break; 1507 /* fall through */ 1508 case QUEUE_CLEAN: 1509 /* 1510 * nbp is NULL. 1511 */ 1512 break; 1513 } 1514 } 1515 1516 /* 1517 * Sanity Checks 1518 */ 1519 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp)); 1520 1521 /* 1522 * Note: we no longer distinguish between VMIO and non-VMIO 1523 * buffers. 1524 */ 1525 1526 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); 1527 1528 /* 1529 * If we are defragging then we need a buffer with 1530 * b_kvasize != 0. XXX this situation should no longer 1531 * occur, if defrag is non-zero the buffer's b_kvasize 1532 * should also be non-zero at this point. XXX 1533 */ 1534 if (defrag && bp->b_kvasize == 0) { 1535 printf("Warning: defrag empty buffer %p\n", bp); 1536 continue; 1537 } 1538 1539 /* 1540 * Start freeing the bp. This is somewhat involved. nbp 1541 * remains valid only for QUEUE_EMPTY[KVA] bp's. 1542 */ 1543 1544 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) 1545 panic("getnewbuf: locked buf"); 1546 bremfree(bp); 1547 1548 if (qindex == QUEUE_CLEAN) { 1549 if (bp->b_flags & B_VMIO) { 1550 bp->b_flags &= ~B_ASYNC; 1551 vfs_vmio_release(bp); 1552 } 1553 if (bp->b_vp) 1554 brelvp(bp); 1555 } 1556 1557 /* 1558 * NOTE: nbp is now entirely invalid. We can only restart 1559 * the scan from this point on. 1560 * 1561 * Get the rest of the buffer freed up. b_kva* is still 1562 * valid after this operation. 1563 */ 1564 1565 if (bp->b_rcred != NOCRED) { 1566 crfree(bp->b_rcred); 1567 bp->b_rcred = NOCRED; 1568 } 1569 if (bp->b_wcred != NOCRED) { 1570 crfree(bp->b_wcred); 1571 bp->b_wcred = NOCRED; 1572 } 1573 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_deallocate) 1574 (*bioops.io_deallocate)(bp); 1575 if (bp->b_xflags & BX_BKGRDINPROG) 1576 panic("losing buffer 3"); 1577 LIST_REMOVE(bp, b_hash); 1578 LIST_INSERT_HEAD(&invalhash, bp, b_hash); 1579 1580 if (bp->b_bufsize) 1581 allocbuf(bp, 0); 1582 1583 bp->b_flags = 0; 1584 bp->b_ioflags = 0; 1585 bp->b_xflags = 0; 1586 bp->b_dev = NODEV; 1587 bp->b_vp = NULL; 1588 bp->b_blkno = bp->b_lblkno = 0; 1589 bp->b_offset = NOOFFSET; 1590 bp->b_iodone = 0; 1591 bp->b_error = 0; 1592 bp->b_resid = 0; 1593 bp->b_bcount = 0; 1594 bp->b_npages = 0; 1595 bp->b_dirtyoff = bp->b_dirtyend = 0; 1596 1597 LIST_INIT(&bp->b_dep); 1598 1599 /* 1600 * If we are defragging then free the buffer. 1601 */ 1602 if (defrag) { 1603 bp->b_flags |= B_INVAL; 1604 bfreekva(bp); 1605 brelse(bp); 1606 defrag = 0; 1607 goto restart; 1608 } 1609 1610 /* 1611 * If we are a normal process then deal with bufspace 1612 * hysteresis. A normal process tries to keep bufspace 1613 * between lobufspace and hibufspace. Note: if we encounter 1614 * a buffer with b_kvasize == 0 then it means we started 1615 * our scan on the EMPTY list and should allocate a new 1616 * buffer. 1617 */ 1618 if (isspecial == 0) { 1619 if (bufspace > hibufspace) 1620 flushingbufs = 1; 1621 if (flushingbufs && bp->b_kvasize != 0) { 1622 bp->b_flags |= B_INVAL; 1623 bfreekva(bp); 1624 brelse(bp); 1625 goto restart; 1626 } 1627 if (bufspace < lobufspace) 1628 flushingbufs = 0; 1629 } 1630 break; 1631 } 1632 1633 /* 1634 * If we exhausted our list, sleep as appropriate. We may have to 1635 * wakeup various daemons and write out some dirty buffers. 1636 * 1637 * Generally we are sleeping due to insufficient buffer space. 1638 */ 1639 1640 if (bp == NULL) { 1641 int flags; 1642 char *waitmsg; 1643 1644 if (defrag) { 1645 flags = VFS_BIO_NEED_BUFSPACE; 1646 waitmsg = "nbufkv"; 1647 } else if (bufspace >= hibufspace) { 1648 waitmsg = "nbufbs"; 1649 flags = VFS_BIO_NEED_BUFSPACE; 1650 } else { 1651 waitmsg = "newbuf"; 1652 flags = VFS_BIO_NEED_ANY; 1653 } 1654 1655 bd_speedup(); /* heeeelp */ 1656 1657 needsbuffer |= flags; 1658 while (needsbuffer & flags) { 1659 if (tsleep(&needsbuffer, (PRIBIO + 4) | slpflag, 1660 waitmsg, slptimeo)) 1661 return (NULL); 1662 } 1663 } else { 1664 /* 1665 * We finally have a valid bp. We aren't quite out of the 1666 * woods, we still have to reserve kva space. In order 1667 * to keep fragmentation sane we only allocate kva in 1668 * BKVASIZE chunks. 1669 */ 1670 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 1671 1672 if (maxsize != bp->b_kvasize) { 1673 vm_offset_t addr = 0; 1674 1675 bfreekva(bp); 1676 1677 if (vm_map_findspace(buffer_map, 1678 vm_map_min(buffer_map), maxsize, &addr)) { 1679 /* 1680 * Uh oh. Buffer map is to fragmented. We 1681 * must defragment the map. 1682 */ 1683 ++bufdefragcnt; 1684 defrag = 1; 1685 bp->b_flags |= B_INVAL; 1686 brelse(bp); 1687 goto restart; 1688 } 1689 if (addr) { 1690 vm_map_insert(buffer_map, NULL, 0, 1691 addr, addr + maxsize, 1692 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT); 1693 1694 bp->b_kvabase = (caddr_t) addr; 1695 bp->b_kvasize = maxsize; 1696 bufspace += bp->b_kvasize; 1697 ++bufreusecnt; 1698 } 1699 } 1700 bp->b_data = bp->b_kvabase; 1701 } 1702 return(bp); 1703} 1704 1705/* 1706 * waitfreebuffers: 1707 * 1708 * Wait for sufficient free buffers. Only called from normal processes. 1709 */ 1710 1711static void 1712waitfreebuffers(int slpflag, int slptimeo) 1713{ 1714 while (numfreebuffers < hifreebuffers) { 1715 if (numfreebuffers >= hifreebuffers) 1716 break; 1717 needsbuffer |= VFS_BIO_NEED_FREE; 1718 if (tsleep(&needsbuffer, (PRIBIO + 4)|slpflag, "biofre", slptimeo)) 1719 break; 1720 } 1721} 1722 1723/* 1724 * buf_daemon: 1725 * 1726 * buffer flushing daemon. Buffers are normally flushed by the 1727 * update daemon but if it cannot keep up this process starts to 1728 * take the load in an attempt to prevent getnewbuf() from blocking. 1729 */ 1730 1731static struct proc *bufdaemonproc; 1732static int bd_interval; 1733static int bd_flushto; 1734static int bd_flushinc; 1735 1736static struct kproc_desc buf_kp = { 1737 "bufdaemon", 1738 buf_daemon, 1739 &bufdaemonproc 1740}; 1741SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp) 1742 1743static void 1744buf_daemon() 1745{ 1746 int s; 1747 1748 /* 1749 * This process needs to be suspended prior to shutdown sync. 1750 */ 1751 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc, bufdaemonproc, 1752 SHUTDOWN_PRI_LAST); 1753 1754 /* 1755 * This process is allowed to take the buffer cache to the limit 1756 */ 1757 curproc->p_flag |= P_BUFEXHAUST; 1758 s = splbio(); 1759 1760 bd_interval = 5 * hz; /* dynamically adjusted */ 1761 bd_flushto = hidirtybuffers; /* dynamically adjusted */ 1762 bd_flushinc = 1; 1763 1764 for (;;) { 1765 kproc_suspend_loop(bufdaemonproc); 1766 1767 bd_request = 0; 1768 1769 /* 1770 * Do the flush. Limit the number of buffers we flush in one 1771 * go. The failure condition occurs when processes are writing 1772 * buffers faster then we can dispose of them. In this case 1773 * we may be flushing so often that the previous set of flushes 1774 * have not had time to complete, causing us to run out of 1775 * physical buffers and block. 1776 */ 1777 { 1778 int runcount = maxbdrun; 1779 1780 while (numdirtybuffers > bd_flushto && runcount) { 1781 --runcount; 1782 if (flushbufqueues() == 0) 1783 break; 1784 } 1785 } 1786 1787 if (bd_request || 1788 tsleep(&bd_request, PVM, "psleep", bd_interval) == 0) { 1789 /* 1790 * Another request is pending or we were woken up 1791 * without timing out. Flush more. 1792 */ 1793 --bd_flushto; 1794 if (bd_flushto >= numdirtybuffers - 5) { 1795 bd_flushto = numdirtybuffers - 10; 1796 bd_flushinc = 1; 1797 } 1798 if (bd_flushto < 2) 1799 bd_flushto = 2; 1800 } else { 1801 /* 1802 * We slept and timed out, we can slow down. 1803 */ 1804 bd_flushto += bd_flushinc; 1805 if (bd_flushto > hidirtybuffers) 1806 bd_flushto = hidirtybuffers; 1807 ++bd_flushinc; 1808 if (bd_flushinc > hidirtybuffers / 20 + 1) 1809 bd_flushinc = hidirtybuffers / 20 + 1; 1810 } 1811 1812 /* 1813 * Set the interval on a linear scale based on hidirtybuffers 1814 * with a maximum frequency of 1/10 second. 1815 */ 1816 bd_interval = bd_flushto * 5 * hz / hidirtybuffers; 1817 if (bd_interval < hz / 10) 1818 bd_interval = hz / 10; 1819 } 1820} 1821 1822/* 1823 * flushbufqueues: 1824 * 1825 * Try to flush a buffer in the dirty queue. We must be careful to 1826 * free up B_INVAL buffers instead of write them, which NFS is 1827 * particularly sensitive to. 1828 */ 1829 1830static int 1831flushbufqueues(void) 1832{ 1833 struct buf *bp; 1834 int r = 0; 1835 1836 bp = TAILQ_FIRST(&bufqueues[QUEUE_DIRTY]); 1837 1838 while (bp) { 1839 KASSERT((bp->b_flags & B_DELWRI), ("unexpected clean buffer %p", bp)); 1840 if ((bp->b_flags & B_DELWRI) != 0 && 1841 (bp->b_xflags & BX_BKGRDINPROG) == 0) { 1842 if (bp->b_flags & B_INVAL) { 1843 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) 1844 panic("flushbufqueues: locked buf"); 1845 bremfree(bp); 1846 brelse(bp); 1847 ++r; 1848 break; 1849 } 1850 if (LIST_FIRST(&bp->b_dep) != NULL && 1851 bioops.io_countdeps && 1852 (bp->b_flags & B_DEFERRED) == 0 && 1853 (*bioops.io_countdeps)(bp, 0)) { 1854 TAILQ_REMOVE(&bufqueues[QUEUE_DIRTY], 1855 bp, b_freelist); 1856 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], 1857 bp, b_freelist); 1858 bp->b_flags |= B_DEFERRED; 1859 bp = TAILQ_FIRST(&bufqueues[QUEUE_DIRTY]); 1860 continue; 1861 } 1862 vfs_bio_awrite(bp); 1863 ++r; 1864 break; 1865 } 1866 bp = TAILQ_NEXT(bp, b_freelist); 1867 } 1868 return (r); 1869} 1870 1871/* 1872 * Check to see if a block is currently memory resident. 1873 */ 1874struct buf * 1875incore(struct vnode * vp, daddr_t blkno) 1876{ 1877 struct buf *bp; 1878 1879 int s = splbio(); 1880 bp = gbincore(vp, blkno); 1881 splx(s); 1882 return (bp); 1883} 1884 1885/* 1886 * Returns true if no I/O is needed to access the 1887 * associated VM object. This is like incore except 1888 * it also hunts around in the VM system for the data. 1889 */ 1890 1891int 1892inmem(struct vnode * vp, daddr_t blkno) 1893{ 1894 vm_object_t obj; 1895 vm_offset_t toff, tinc, size; 1896 vm_page_t m; 1897 vm_ooffset_t off; 1898 1899 if (incore(vp, blkno)) 1900 return 1; 1901 if (vp->v_mount == NULL) 1902 return 0; 1903 if ((vp->v_object == NULL) || (vp->v_flag & VOBJBUF) == 0) 1904 return 0; 1905 1906 obj = vp->v_object; 1907 size = PAGE_SIZE; 1908 if (size > vp->v_mount->mnt_stat.f_iosize) 1909 size = vp->v_mount->mnt_stat.f_iosize; 1910 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 1911 1912 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 1913 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 1914 if (!m) 1915 return 0; 1916 tinc = size; 1917 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 1918 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 1919 if (vm_page_is_valid(m, 1920 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 1921 return 0; 1922 } 1923 return 1; 1924} 1925 1926/* 1927 * vfs_setdirty: 1928 * 1929 * Sets the dirty range for a buffer based on the status of the dirty 1930 * bits in the pages comprising the buffer. 1931 * 1932 * The range is limited to the size of the buffer. 1933 * 1934 * This routine is primarily used by NFS, but is generalized for the 1935 * B_VMIO case. 1936 */ 1937static void 1938vfs_setdirty(struct buf *bp) 1939{ 1940 int i; 1941 vm_object_t object; 1942 1943 /* 1944 * Degenerate case - empty buffer 1945 */ 1946 1947 if (bp->b_bufsize == 0) 1948 return; 1949 1950 /* 1951 * We qualify the scan for modified pages on whether the 1952 * object has been flushed yet. The OBJ_WRITEABLE flag 1953 * is not cleared simply by protecting pages off. 1954 */ 1955 1956 if ((bp->b_flags & B_VMIO) == 0) 1957 return; 1958 1959 object = bp->b_pages[0]->object; 1960 1961 if ((object->flags & OBJ_WRITEABLE) && !(object->flags & OBJ_MIGHTBEDIRTY)) 1962 printf("Warning: object %p writeable but not mightbedirty\n", object); 1963 if (!(object->flags & OBJ_WRITEABLE) && (object->flags & OBJ_MIGHTBEDIRTY)) 1964 printf("Warning: object %p mightbedirty but not writeable\n", object); 1965 1966 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) { 1967 vm_offset_t boffset; 1968 vm_offset_t eoffset; 1969 1970 /* 1971 * test the pages to see if they have been modified directly 1972 * by users through the VM system. 1973 */ 1974 for (i = 0; i < bp->b_npages; i++) { 1975 vm_page_flag_clear(bp->b_pages[i], PG_ZERO); 1976 vm_page_test_dirty(bp->b_pages[i]); 1977 } 1978 1979 /* 1980 * Calculate the encompassing dirty range, boffset and eoffset, 1981 * (eoffset - boffset) bytes. 1982 */ 1983 1984 for (i = 0; i < bp->b_npages; i++) { 1985 if (bp->b_pages[i]->dirty) 1986 break; 1987 } 1988 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 1989 1990 for (i = bp->b_npages - 1; i >= 0; --i) { 1991 if (bp->b_pages[i]->dirty) { 1992 break; 1993 } 1994 } 1995 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 1996 1997 /* 1998 * Fit it to the buffer. 1999 */ 2000 2001 if (eoffset > bp->b_bcount) 2002 eoffset = bp->b_bcount; 2003 2004 /* 2005 * If we have a good dirty range, merge with the existing 2006 * dirty range. 2007 */ 2008 2009 if (boffset < eoffset) { 2010 if (bp->b_dirtyoff > boffset) 2011 bp->b_dirtyoff = boffset; 2012 if (bp->b_dirtyend < eoffset) 2013 bp->b_dirtyend = eoffset; 2014 } 2015 } 2016} 2017 2018/* 2019 * getblk: 2020 * 2021 * Get a block given a specified block and offset into a file/device. 2022 * The buffers B_DONE bit will be cleared on return, making it almost 2023 * ready for an I/O initiation. B_INVAL may or may not be set on 2024 * return. The caller should clear B_INVAL prior to initiating a 2025 * READ. 2026 * 2027 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2028 * an existing buffer. 2029 * 2030 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2031 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2032 * and then cleared based on the backing VM. If the previous buffer is 2033 * non-0-sized but invalid, B_CACHE will be cleared. 2034 * 2035 * If getblk() must create a new buffer, the new buffer is returned with 2036 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2037 * case it is returned with B_INVAL clear and B_CACHE set based on the 2038 * backing VM. 2039 * 2040 * getblk() also forces a VOP_BWRITE() for any B_DELWRI buffer whos 2041 * B_CACHE bit is clear. 2042 * 2043 * What this means, basically, is that the caller should use B_CACHE to 2044 * determine whether the buffer is fully valid or not and should clear 2045 * B_INVAL prior to issuing a read. If the caller intends to validate 2046 * the buffer by loading its data area with something, the caller needs 2047 * to clear B_INVAL. If the caller does this without issuing an I/O, 2048 * the caller should set B_CACHE ( as an optimization ), else the caller 2049 * should issue the I/O and biodone() will set B_CACHE if the I/O was 2050 * a write attempt or if it was a successfull read. If the caller 2051 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 2052 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 2053 */ 2054struct buf * 2055getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo) 2056{ 2057 struct buf *bp; 2058 int s; 2059 struct bufhashhdr *bh; 2060 2061 if (size > MAXBSIZE) 2062 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 2063 2064 s = splbio(); 2065loop: 2066 /* 2067 * Block if we are low on buffers. Certain processes are allowed 2068 * to completely exhaust the buffer cache. 2069 * 2070 * If this check ever becomes a bottleneck it may be better to 2071 * move it into the else, when gbincore() fails. At the moment 2072 * it isn't a problem. 2073 */ 2074 if (!curproc || (curproc->p_flag & P_BUFEXHAUST)) { 2075 if (numfreebuffers == 0) { 2076 if (!curproc) 2077 return NULL; 2078 needsbuffer |= VFS_BIO_NEED_ANY; 2079 tsleep(&needsbuffer, (PRIBIO + 4) | slpflag, "newbuf", 2080 slptimeo); 2081 } 2082 } else if (numfreebuffers < lofreebuffers) { 2083 waitfreebuffers(slpflag, slptimeo); 2084 } 2085 2086 if ((bp = gbincore(vp, blkno))) { 2087 /* 2088 * Buffer is in-core. If the buffer is not busy, it must 2089 * be on a queue. 2090 */ 2091 2092 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) { 2093 if (BUF_TIMELOCK(bp, LK_EXCLUSIVE | LK_SLEEPFAIL, 2094 "getblk", slpflag, slptimeo) == ENOLCK) 2095 goto loop; 2096 splx(s); 2097 return (struct buf *) NULL; 2098 } 2099 2100 /* 2101 * The buffer is locked. B_CACHE is cleared if the buffer is 2102 * invalid. Ohterwise, for a non-VMIO buffer, B_CACHE is set 2103 * and for a VMIO buffer B_CACHE is adjusted according to the 2104 * backing VM cache. 2105 */ 2106 if (bp->b_flags & B_INVAL) 2107 bp->b_flags &= ~B_CACHE; 2108 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 2109 bp->b_flags |= B_CACHE; 2110 bremfree(bp); 2111 2112 /* 2113 * check for size inconsistancies for non-VMIO case. 2114 */ 2115 2116 if (bp->b_bcount != size) { 2117 if ((bp->b_flags & B_VMIO) == 0 || 2118 (size > bp->b_kvasize)) { 2119 if (bp->b_flags & B_DELWRI) { 2120 bp->b_flags |= B_NOCACHE; 2121 BUF_WRITE(bp); 2122 } else { 2123 if ((bp->b_flags & B_VMIO) && 2124 (LIST_FIRST(&bp->b_dep) == NULL)) { 2125 bp->b_flags |= B_RELBUF; 2126 brelse(bp); 2127 } else { 2128 bp->b_flags |= B_NOCACHE; 2129 BUF_WRITE(bp); 2130 } 2131 } 2132 goto loop; 2133 } 2134 } 2135 2136 /* 2137 * If the size is inconsistant in the VMIO case, we can resize 2138 * the buffer. This might lead to B_CACHE getting set or 2139 * cleared. If the size has not changed, B_CACHE remains 2140 * unchanged from its previous state. 2141 */ 2142 2143 if (bp->b_bcount != size) 2144 allocbuf(bp, size); 2145 2146 KASSERT(bp->b_offset != NOOFFSET, 2147 ("getblk: no buffer offset")); 2148 2149 /* 2150 * A buffer with B_DELWRI set and B_CACHE clear must 2151 * be committed before we can return the buffer in 2152 * order to prevent the caller from issuing a read 2153 * ( due to B_CACHE not being set ) and overwriting 2154 * it. 2155 * 2156 * Most callers, including NFS and FFS, need this to 2157 * operate properly either because they assume they 2158 * can issue a read if B_CACHE is not set, or because 2159 * ( for example ) an uncached B_DELWRI might loop due 2160 * to softupdates re-dirtying the buffer. In the latter 2161 * case, B_CACHE is set after the first write completes, 2162 * preventing further loops. 2163 */ 2164 2165 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 2166 BUF_WRITE(bp); 2167 goto loop; 2168 } 2169 2170 splx(s); 2171 bp->b_flags &= ~B_DONE; 2172 } else { 2173 /* 2174 * Buffer is not in-core, create new buffer. The buffer 2175 * returned by getnewbuf() is locked. Note that the returned 2176 * buffer is also considered valid (not marked B_INVAL). 2177 */ 2178 int bsize, maxsize, vmio; 2179 off_t offset; 2180 2181 if (vn_isdisk(vp, NULL)) 2182 bsize = DEV_BSIZE; 2183 else if (vp->v_mountedhere) 2184 bsize = vp->v_mountedhere->mnt_stat.f_iosize; 2185 else if (vp->v_mount) 2186 bsize = vp->v_mount->mnt_stat.f_iosize; 2187 else 2188 bsize = size; 2189 2190 offset = (off_t)blkno * bsize; 2191 vmio = (vp->v_object != 0) && (vp->v_flag & VOBJBUF); 2192 maxsize = vmio ? size + (offset & PAGE_MASK) : size; 2193 maxsize = imax(maxsize, bsize); 2194 2195 if ((bp = getnewbuf(slpflag, slptimeo, size, maxsize)) == NULL) { 2196 if (slpflag || slptimeo) { 2197 splx(s); 2198 return NULL; 2199 } 2200 goto loop; 2201 } 2202 2203 /* 2204 * This code is used to make sure that a buffer is not 2205 * created while the getnewbuf routine is blocked. 2206 * This can be a problem whether the vnode is locked or not. 2207 * If the buffer is created out from under us, we have to 2208 * throw away the one we just created. There is now window 2209 * race because we are safely running at splbio() from the 2210 * point of the duplicate buffer creation through to here, 2211 * and we've locked the buffer. 2212 */ 2213 if (gbincore(vp, blkno)) { 2214 bp->b_flags |= B_INVAL; 2215 brelse(bp); 2216 goto loop; 2217 } 2218 2219 /* 2220 * Insert the buffer into the hash, so that it can 2221 * be found by incore. 2222 */ 2223 bp->b_blkno = bp->b_lblkno = blkno; 2224 bp->b_offset = offset; 2225 2226 bgetvp(vp, bp); 2227 LIST_REMOVE(bp, b_hash); 2228 bh = bufhash(vp, blkno); 2229 LIST_INSERT_HEAD(bh, bp, b_hash); 2230 2231 /* 2232 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 2233 * buffer size starts out as 0, B_CACHE will be set by 2234 * allocbuf() for the VMIO case prior to it testing the 2235 * backing store for validity. 2236 */ 2237 2238 if (vmio) { 2239 bp->b_flags |= B_VMIO; 2240#if defined(VFS_BIO_DEBUG) 2241 if (vp->v_type != VREG && vp->v_type != VBLK) 2242 printf("getblk: vmioing file type %d???\n", vp->v_type); 2243#endif 2244 } else { 2245 bp->b_flags &= ~B_VMIO; 2246 } 2247 2248 allocbuf(bp, size); 2249 2250 splx(s); 2251 bp->b_flags &= ~B_DONE; 2252 } 2253 return (bp); 2254} 2255 2256/* 2257 * Get an empty, disassociated buffer of given size. The buffer is initially 2258 * set to B_INVAL. 2259 */ 2260struct buf * 2261geteblk(int size) 2262{ 2263 struct buf *bp; 2264 int s; 2265 int maxsize; 2266 2267 maxsize = (size + BKVAMASK) & ~BKVAMASK; 2268 2269 s = splbio(); 2270 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0); 2271 splx(s); 2272 allocbuf(bp, size); 2273 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 2274 return (bp); 2275} 2276 2277 2278/* 2279 * This code constitutes the buffer memory from either anonymous system 2280 * memory (in the case of non-VMIO operations) or from an associated 2281 * VM object (in the case of VMIO operations). This code is able to 2282 * resize a buffer up or down. 2283 * 2284 * Note that this code is tricky, and has many complications to resolve 2285 * deadlock or inconsistant data situations. Tread lightly!!! 2286 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 2287 * the caller. Calling this code willy nilly can result in the loss of data. 2288 * 2289 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 2290 * B_CACHE for the non-VMIO case. 2291 */ 2292 2293int 2294allocbuf(struct buf *bp, int size) 2295{ 2296 int newbsize, mbsize; 2297 int i; 2298 2299 if (BUF_REFCNT(bp) == 0) 2300 panic("allocbuf: buffer not busy"); 2301 2302 if (bp->b_kvasize < size) 2303 panic("allocbuf: buffer too small"); 2304 2305 if ((bp->b_flags & B_VMIO) == 0) { 2306 caddr_t origbuf; 2307 int origbufsize; 2308 /* 2309 * Just get anonymous memory from the kernel. Don't 2310 * mess with B_CACHE. 2311 */ 2312 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2313#if !defined(NO_B_MALLOC) 2314 if (bp->b_flags & B_MALLOC) 2315 newbsize = mbsize; 2316 else 2317#endif 2318 newbsize = round_page(size); 2319 2320 if (newbsize < bp->b_bufsize) { 2321#if !defined(NO_B_MALLOC) 2322 /* 2323 * malloced buffers are not shrunk 2324 */ 2325 if (bp->b_flags & B_MALLOC) { 2326 if (newbsize) { 2327 bp->b_bcount = size; 2328 } else { 2329 free(bp->b_data, M_BIOBUF); 2330 bufmallocspace -= bp->b_bufsize; 2331 runningbufspace -= bp->b_bufsize; 2332 if (bp->b_bufsize) 2333 bufspacewakeup(); 2334 bp->b_data = bp->b_kvabase; 2335 bp->b_bufsize = 0; 2336 bp->b_bcount = 0; 2337 bp->b_flags &= ~B_MALLOC; 2338 } 2339 return 1; 2340 } 2341#endif 2342 vm_hold_free_pages( 2343 bp, 2344 (vm_offset_t) bp->b_data + newbsize, 2345 (vm_offset_t) bp->b_data + bp->b_bufsize); 2346 } else if (newbsize > bp->b_bufsize) { 2347#if !defined(NO_B_MALLOC) 2348 /* 2349 * We only use malloced memory on the first allocation. 2350 * and revert to page-allocated memory when the buffer 2351 * grows. 2352 */ 2353 if ( (bufmallocspace < maxbufmallocspace) && 2354 (bp->b_bufsize == 0) && 2355 (mbsize <= PAGE_SIZE/2)) { 2356 2357 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 2358 bp->b_bufsize = mbsize; 2359 bp->b_bcount = size; 2360 bp->b_flags |= B_MALLOC; 2361 bufmallocspace += mbsize; 2362 runningbufspace += bp->b_bufsize; 2363 return 1; 2364 } 2365#endif 2366 origbuf = NULL; 2367 origbufsize = 0; 2368#if !defined(NO_B_MALLOC) 2369 /* 2370 * If the buffer is growing on its other-than-first allocation, 2371 * then we revert to the page-allocation scheme. 2372 */ 2373 if (bp->b_flags & B_MALLOC) { 2374 origbuf = bp->b_data; 2375 origbufsize = bp->b_bufsize; 2376 bp->b_data = bp->b_kvabase; 2377 bufmallocspace -= bp->b_bufsize; 2378 runningbufspace -= bp->b_bufsize; 2379 if (bp->b_bufsize) 2380 bufspacewakeup(); 2381 bp->b_bufsize = 0; 2382 bp->b_flags &= ~B_MALLOC; 2383 newbsize = round_page(newbsize); 2384 } 2385#endif 2386 vm_hold_load_pages( 2387 bp, 2388 (vm_offset_t) bp->b_data + bp->b_bufsize, 2389 (vm_offset_t) bp->b_data + newbsize); 2390#if !defined(NO_B_MALLOC) 2391 if (origbuf) { 2392 bcopy(origbuf, bp->b_data, origbufsize); 2393 free(origbuf, M_BIOBUF); 2394 } 2395#endif 2396 } 2397 } else { 2398 vm_page_t m; 2399 int desiredpages; 2400 2401 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2402 desiredpages = (size == 0) ? 0 : 2403 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 2404 2405#if !defined(NO_B_MALLOC) 2406 if (bp->b_flags & B_MALLOC) 2407 panic("allocbuf: VMIO buffer can't be malloced"); 2408#endif 2409 /* 2410 * Set B_CACHE initially if buffer is 0 length or will become 2411 * 0-length. 2412 */ 2413 if (size == 0 || bp->b_bufsize == 0) 2414 bp->b_flags |= B_CACHE; 2415 2416 if (newbsize < bp->b_bufsize) { 2417 /* 2418 * DEV_BSIZE aligned new buffer size is less then the 2419 * DEV_BSIZE aligned existing buffer size. Figure out 2420 * if we have to remove any pages. 2421 */ 2422 if (desiredpages < bp->b_npages) { 2423 for (i = desiredpages; i < bp->b_npages; i++) { 2424 /* 2425 * the page is not freed here -- it 2426 * is the responsibility of 2427 * vnode_pager_setsize 2428 */ 2429 m = bp->b_pages[i]; 2430 KASSERT(m != bogus_page, 2431 ("allocbuf: bogus page found")); 2432 while (vm_page_sleep_busy(m, TRUE, "biodep")) 2433 ; 2434 2435 bp->b_pages[i] = NULL; 2436 vm_page_unwire(m, 0); 2437 } 2438 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) + 2439 (desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages)); 2440 bp->b_npages = desiredpages; 2441 } 2442 } else if (size > bp->b_bcount) { 2443 /* 2444 * We are growing the buffer, possibly in a 2445 * byte-granular fashion. 2446 */ 2447 struct vnode *vp; 2448 vm_object_t obj; 2449 vm_offset_t toff; 2450 vm_offset_t tinc; 2451 2452 /* 2453 * Step 1, bring in the VM pages from the object, 2454 * allocating them if necessary. We must clear 2455 * B_CACHE if these pages are not valid for the 2456 * range covered by the buffer. 2457 */ 2458 2459 vp = bp->b_vp; 2460 obj = vp->v_object; 2461 2462 while (bp->b_npages < desiredpages) { 2463 vm_page_t m; 2464 vm_pindex_t pi; 2465 2466 pi = OFF_TO_IDX(bp->b_offset) + bp->b_npages; 2467 if ((m = vm_page_lookup(obj, pi)) == NULL) { 2468 m = vm_page_alloc(obj, pi, VM_ALLOC_NORMAL); 2469 if (m == NULL) { 2470 VM_WAIT; 2471 vm_pageout_deficit += desiredpages - bp->b_npages; 2472 } else { 2473 vm_page_wire(m); 2474 vm_page_wakeup(m); 2475 bp->b_flags &= ~B_CACHE; 2476 bp->b_pages[bp->b_npages] = m; 2477 ++bp->b_npages; 2478 } 2479 continue; 2480 } 2481 2482 /* 2483 * We found a page. If we have to sleep on it, 2484 * retry because it might have gotten freed out 2485 * from under us. 2486 * 2487 * We can only test PG_BUSY here. Blocking on 2488 * m->busy might lead to a deadlock: 2489 * 2490 * vm_fault->getpages->cluster_read->allocbuf 2491 * 2492 */ 2493 2494 if (vm_page_sleep_busy(m, FALSE, "pgtblk")) 2495 continue; 2496 2497 /* 2498 * We have a good page. Should we wakeup the 2499 * page daemon? 2500 */ 2501 if ((curproc != pageproc) && 2502 ((m->queue - m->pc) == PQ_CACHE) && 2503 ((cnt.v_free_count + cnt.v_cache_count) < 2504 (cnt.v_free_min + cnt.v_cache_min))) { 2505 pagedaemon_wakeup(); 2506 } 2507 vm_page_flag_clear(m, PG_ZERO); 2508 vm_page_wire(m); 2509 bp->b_pages[bp->b_npages] = m; 2510 ++bp->b_npages; 2511 } 2512 2513 /* 2514 * Step 2. We've loaded the pages into the buffer, 2515 * we have to figure out if we can still have B_CACHE 2516 * set. Note that B_CACHE is set according to the 2517 * byte-granular range ( bcount and size ), new the 2518 * aligned range ( newbsize ). 2519 * 2520 * The VM test is against m->valid, which is DEV_BSIZE 2521 * aligned. Needless to say, the validity of the data 2522 * needs to also be DEV_BSIZE aligned. Note that this 2523 * fails with NFS if the server or some other client 2524 * extends the file's EOF. If our buffer is resized, 2525 * B_CACHE may remain set! XXX 2526 */ 2527 2528 toff = bp->b_bcount; 2529 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 2530 2531 while ((bp->b_flags & B_CACHE) && toff < size) { 2532 vm_pindex_t pi; 2533 2534 if (tinc > (size - toff)) 2535 tinc = size - toff; 2536 2537 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 2538 PAGE_SHIFT; 2539 2540 vfs_buf_test_cache( 2541 bp, 2542 bp->b_offset, 2543 toff, 2544 tinc, 2545 bp->b_pages[pi] 2546 ); 2547 toff += tinc; 2548 tinc = PAGE_SIZE; 2549 } 2550 2551 /* 2552 * Step 3, fixup the KVM pmap. Remember that 2553 * bp->b_data is relative to bp->b_offset, but 2554 * bp->b_offset may be offset into the first page. 2555 */ 2556 2557 bp->b_data = (caddr_t) 2558 trunc_page((vm_offset_t)bp->b_data); 2559 pmap_qenter( 2560 (vm_offset_t)bp->b_data, 2561 bp->b_pages, 2562 bp->b_npages 2563 ); 2564 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 2565 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 2566 } 2567 } 2568 runningbufspace += (newbsize - bp->b_bufsize); 2569 if (newbsize < bp->b_bufsize) 2570 bufspacewakeup(); 2571 bp->b_bufsize = newbsize; /* actual buffer allocation */ 2572 bp->b_bcount = size; /* requested buffer size */ 2573 return 1; 2574} 2575 2576/* 2577 * bufwait: 2578 * 2579 * Wait for buffer I/O completion, returning error status. The buffer 2580 * is left locked and B_DONE on return. B_EINTR is converted into a EINTR 2581 * error and cleared. 2582 */ 2583int 2584bufwait(register struct buf * bp) 2585{ 2586 int s; 2587 2588 s = splbio(); 2589 while ((bp->b_flags & B_DONE) == 0) { 2590 if (bp->b_iocmd == BIO_READ) 2591 tsleep(bp, PRIBIO, "biord", 0); 2592 else 2593 tsleep(bp, PRIBIO, "biowr", 0); 2594 } 2595 splx(s); 2596 if (bp->b_flags & B_EINTR) { 2597 bp->b_flags &= ~B_EINTR; 2598 return (EINTR); 2599 } 2600 if (bp->b_ioflags & BIO_ERROR) { 2601 return (bp->b_error ? bp->b_error : EIO); 2602 } else { 2603 return (0); 2604 } 2605} 2606 2607 /* 2608 * Call back function from struct bio back up to struct buf. 2609 * The corresponding initialization lives in sys/conf.h:DEV_STRATEGY(). 2610 */ 2611void 2612bufdonebio(struct bio *bp) 2613{ 2614 bufdone(bp->bio_caller2); 2615} 2616 2617/* 2618 * bufdone: 2619 * 2620 * Finish I/O on a buffer, optionally calling a completion function. 2621 * This is usually called from an interrupt so process blocking is 2622 * not allowed. 2623 * 2624 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 2625 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 2626 * assuming B_INVAL is clear. 2627 * 2628 * For the VMIO case, we set B_CACHE if the op was a read and no 2629 * read error occured, or if the op was a write. B_CACHE is never 2630 * set if the buffer is invalid or otherwise uncacheable. 2631 * 2632 * biodone does not mess with B_INVAL, allowing the I/O routine or the 2633 * initiator to leave B_INVAL set to brelse the buffer out of existance 2634 * in the biodone routine. 2635 */ 2636void 2637bufdone(struct buf *bp) 2638{ 2639 int s; 2640 void (*biodone) __P((struct buf *)); 2641 2642 s = splbio(); 2643 2644 KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp, BUF_REFCNT(bp))); 2645 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 2646 2647 bp->b_flags |= B_DONE; 2648 2649 if (bp->b_iocmd == BIO_DELETE) { 2650 brelse(bp); 2651 splx(s); 2652 return; 2653 } 2654 2655 if (bp->b_iocmd == BIO_WRITE) { 2656 vwakeup(bp); 2657 } 2658 2659 /* call optional completion function if requested */ 2660 if (bp->b_iodone != NULL) { 2661 biodone = bp->b_iodone; 2662 bp->b_iodone = NULL; 2663 (*biodone) (bp); 2664 splx(s); 2665 return; 2666 } 2667 if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_complete) 2668 (*bioops.io_complete)(bp); 2669 2670 if (bp->b_flags & B_VMIO) { 2671 int i, resid; 2672 vm_ooffset_t foff; 2673 vm_page_t m; 2674 vm_object_t obj; 2675 int iosize; 2676 struct vnode *vp = bp->b_vp; 2677 2678 obj = vp->v_object; 2679 2680#if defined(VFS_BIO_DEBUG) 2681 if (vp->v_usecount == 0) { 2682 panic("biodone: zero vnode ref count"); 2683 } 2684 2685 if (vp->v_object == NULL) { 2686 panic("biodone: missing VM object"); 2687 } 2688 2689 if ((vp->v_flag & VOBJBUF) == 0) { 2690 panic("biodone: vnode is not setup for merged cache"); 2691 } 2692#endif 2693 2694 foff = bp->b_offset; 2695 KASSERT(bp->b_offset != NOOFFSET, 2696 ("biodone: no buffer offset")); 2697 2698 if (!obj) { 2699 panic("biodone: no object"); 2700 } 2701#if defined(VFS_BIO_DEBUG) 2702 if (obj->paging_in_progress < bp->b_npages) { 2703 printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n", 2704 obj->paging_in_progress, bp->b_npages); 2705 } 2706#endif 2707 2708 /* 2709 * Set B_CACHE if the op was a normal read and no error 2710 * occured. B_CACHE is set for writes in the b*write() 2711 * routines. 2712 */ 2713 iosize = bp->b_bcount - bp->b_resid; 2714 if (bp->b_iocmd == BIO_READ && 2715 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 2716 !(bp->b_ioflags & BIO_ERROR)) { 2717 bp->b_flags |= B_CACHE; 2718 } 2719 2720 for (i = 0; i < bp->b_npages; i++) { 2721 int bogusflag = 0; 2722 m = bp->b_pages[i]; 2723 if (m == bogus_page) { 2724 bogusflag = 1; 2725 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 2726 if (!m) { 2727#if defined(VFS_BIO_DEBUG) 2728 printf("biodone: page disappeared\n"); 2729#endif 2730 vm_object_pip_subtract(obj, 1); 2731 bp->b_flags &= ~B_CACHE; 2732 continue; 2733 } 2734 bp->b_pages[i] = m; 2735 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 2736 } 2737#if defined(VFS_BIO_DEBUG) 2738 if (OFF_TO_IDX(foff) != m->pindex) { 2739 printf( 2740"biodone: foff(%lu)/m->pindex(%d) mismatch\n", 2741 (unsigned long)foff, m->pindex); 2742 } 2743#endif 2744 resid = IDX_TO_OFF(m->pindex + 1) - foff; 2745 if (resid > iosize) 2746 resid = iosize; 2747 2748 /* 2749 * In the write case, the valid and clean bits are 2750 * already changed correctly ( see bdwrite() ), so we 2751 * only need to do this here in the read case. 2752 */ 2753 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 2754 vfs_page_set_valid(bp, foff, i, m); 2755 } 2756 vm_page_flag_clear(m, PG_ZERO); 2757 2758 /* 2759 * when debugging new filesystems or buffer I/O methods, this 2760 * is the most common error that pops up. if you see this, you 2761 * have not set the page busy flag correctly!!! 2762 */ 2763 if (m->busy == 0) { 2764 printf("biodone: page busy < 0, " 2765 "pindex: %d, foff: 0x(%x,%x), " 2766 "resid: %d, index: %d\n", 2767 (int) m->pindex, (int)(foff >> 32), 2768 (int) foff & 0xffffffff, resid, i); 2769 if (!vn_isdisk(vp, NULL)) 2770 printf(" iosize: %ld, lblkno: %d, flags: 0x%lx, npages: %d\n", 2771 bp->b_vp->v_mount->mnt_stat.f_iosize, 2772 (int) bp->b_lblkno, 2773 bp->b_flags, bp->b_npages); 2774 else 2775 printf(" VDEV, lblkno: %d, flags: 0x%lx, npages: %d\n", 2776 (int) bp->b_lblkno, 2777 bp->b_flags, bp->b_npages); 2778 printf(" valid: 0x%x, dirty: 0x%x, wired: %d\n", 2779 m->valid, m->dirty, m->wire_count); 2780 panic("biodone: page busy < 0\n"); 2781 } 2782 vm_page_io_finish(m); 2783 vm_object_pip_subtract(obj, 1); 2784 foff += resid; 2785 iosize -= resid; 2786 } 2787 if (obj) 2788 vm_object_pip_wakeupn(obj, 0); 2789 } 2790 /* 2791 * For asynchronous completions, release the buffer now. The brelse 2792 * will do a wakeup there if necessary - so no need to do a wakeup 2793 * here in the async case. The sync case always needs to do a wakeup. 2794 */ 2795 2796 if (bp->b_flags & B_ASYNC) { 2797 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 2798 brelse(bp); 2799 else 2800 bqrelse(bp); 2801 } else { 2802 wakeup(bp); 2803 } 2804 splx(s); 2805} 2806 2807/* 2808 * This routine is called in lieu of iodone in the case of 2809 * incomplete I/O. This keeps the busy status for pages 2810 * consistant. 2811 */ 2812void 2813vfs_unbusy_pages(struct buf * bp) 2814{ 2815 int i; 2816 2817 if (bp->b_flags & B_VMIO) { 2818 struct vnode *vp = bp->b_vp; 2819 vm_object_t obj = vp->v_object; 2820 2821 for (i = 0; i < bp->b_npages; i++) { 2822 vm_page_t m = bp->b_pages[i]; 2823 2824 if (m == bogus_page) { 2825 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 2826 if (!m) { 2827 panic("vfs_unbusy_pages: page missing\n"); 2828 } 2829 bp->b_pages[i] = m; 2830 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 2831 } 2832 vm_object_pip_subtract(obj, 1); 2833 vm_page_flag_clear(m, PG_ZERO); 2834 vm_page_io_finish(m); 2835 } 2836 vm_object_pip_wakeupn(obj, 0); 2837 } 2838} 2839 2840/* 2841 * vfs_page_set_valid: 2842 * 2843 * Set the valid bits in a page based on the supplied offset. The 2844 * range is restricted to the buffer's size. 2845 * 2846 * This routine is typically called after a read completes. 2847 */ 2848static void 2849vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m) 2850{ 2851 vm_ooffset_t soff, eoff; 2852 2853 /* 2854 * Start and end offsets in buffer. eoff - soff may not cross a 2855 * page boundry or cross the end of the buffer. The end of the 2856 * buffer, in this case, is our file EOF, not the allocation size 2857 * of the buffer. 2858 */ 2859 soff = off; 2860 eoff = (off + PAGE_SIZE) & ~PAGE_MASK; 2861 if (eoff > bp->b_offset + bp->b_bcount) 2862 eoff = bp->b_offset + bp->b_bcount; 2863 2864 /* 2865 * Set valid range. This is typically the entire buffer and thus the 2866 * entire page. 2867 */ 2868 if (eoff > soff) { 2869 vm_page_set_validclean( 2870 m, 2871 (vm_offset_t) (soff & PAGE_MASK), 2872 (vm_offset_t) (eoff - soff) 2873 ); 2874 } 2875} 2876 2877/* 2878 * This routine is called before a device strategy routine. 2879 * It is used to tell the VM system that paging I/O is in 2880 * progress, and treat the pages associated with the buffer 2881 * almost as being PG_BUSY. Also the object paging_in_progress 2882 * flag is handled to make sure that the object doesn't become 2883 * inconsistant. 2884 * 2885 * Since I/O has not been initiated yet, certain buffer flags 2886 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 2887 * and should be ignored. 2888 */ 2889void 2890vfs_busy_pages(struct buf * bp, int clear_modify) 2891{ 2892 int i, bogus; 2893 2894 if (bp->b_flags & B_VMIO) { 2895 struct vnode *vp = bp->b_vp; 2896 vm_object_t obj = vp->v_object; 2897 vm_ooffset_t foff; 2898 2899 foff = bp->b_offset; 2900 KASSERT(bp->b_offset != NOOFFSET, 2901 ("vfs_busy_pages: no buffer offset")); 2902 vfs_setdirty(bp); 2903 2904retry: 2905 for (i = 0; i < bp->b_npages; i++) { 2906 vm_page_t m = bp->b_pages[i]; 2907 if (vm_page_sleep_busy(m, FALSE, "vbpage")) 2908 goto retry; 2909 } 2910 2911 bogus = 0; 2912 for (i = 0; i < bp->b_npages; i++) { 2913 vm_page_t m = bp->b_pages[i]; 2914 2915 vm_page_flag_clear(m, PG_ZERO); 2916 if ((bp->b_flags & B_CLUSTER) == 0) { 2917 vm_object_pip_add(obj, 1); 2918 vm_page_io_start(m); 2919 } 2920 2921 /* 2922 * When readying a buffer for a read ( i.e 2923 * clear_modify == 0 ), it is important to do 2924 * bogus_page replacement for valid pages in 2925 * partially instantiated buffers. Partially 2926 * instantiated buffers can, in turn, occur when 2927 * reconstituting a buffer from its VM backing store 2928 * base. We only have to do this if B_CACHE is 2929 * clear ( which causes the I/O to occur in the 2930 * first place ). The replacement prevents the read 2931 * I/O from overwriting potentially dirty VM-backed 2932 * pages. XXX bogus page replacement is, uh, bogus. 2933 * It may not work properly with small-block devices. 2934 * We need to find a better way. 2935 */ 2936 2937 vm_page_protect(m, VM_PROT_NONE); 2938 if (clear_modify) 2939 vfs_page_set_valid(bp, foff, i, m); 2940 else if (m->valid == VM_PAGE_BITS_ALL && 2941 (bp->b_flags & B_CACHE) == 0) { 2942 bp->b_pages[i] = bogus_page; 2943 bogus++; 2944 } 2945 foff = (foff + PAGE_SIZE) & ~PAGE_MASK; 2946 } 2947 if (bogus) 2948 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages); 2949 } 2950} 2951 2952/* 2953 * Tell the VM system that the pages associated with this buffer 2954 * are clean. This is used for delayed writes where the data is 2955 * going to go to disk eventually without additional VM intevention. 2956 * 2957 * Note that while we only really need to clean through to b_bcount, we 2958 * just go ahead and clean through to b_bufsize. 2959 */ 2960static void 2961vfs_clean_pages(struct buf * bp) 2962{ 2963 int i; 2964 2965 if (bp->b_flags & B_VMIO) { 2966 vm_ooffset_t foff; 2967 2968 foff = bp->b_offset; 2969 KASSERT(bp->b_offset != NOOFFSET, 2970 ("vfs_clean_pages: no buffer offset")); 2971 for (i = 0; i < bp->b_npages; i++) { 2972 vm_page_t m = bp->b_pages[i]; 2973 vm_ooffset_t noff = (foff + PAGE_SIZE) & ~PAGE_MASK; 2974 vm_ooffset_t eoff = noff; 2975 2976 if (eoff > bp->b_offset + bp->b_bufsize) 2977 eoff = bp->b_offset + bp->b_bufsize; 2978 vfs_page_set_valid(bp, foff, i, m); 2979 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 2980 foff = noff; 2981 } 2982 } 2983} 2984 2985/* 2986 * vfs_bio_set_validclean: 2987 * 2988 * Set the range within the buffer to valid and clean. The range is 2989 * relative to the beginning of the buffer, b_offset. Note that b_offset 2990 * itself may be offset from the beginning of the first page. 2991 */ 2992 2993void 2994vfs_bio_set_validclean(struct buf *bp, int base, int size) 2995{ 2996 if (bp->b_flags & B_VMIO) { 2997 int i; 2998 int n; 2999 3000 /* 3001 * Fixup base to be relative to beginning of first page. 3002 * Set initial n to be the maximum number of bytes in the 3003 * first page that can be validated. 3004 */ 3005 3006 base += (bp->b_offset & PAGE_MASK); 3007 n = PAGE_SIZE - (base & PAGE_MASK); 3008 3009 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 3010 vm_page_t m = bp->b_pages[i]; 3011 3012 if (n > size) 3013 n = size; 3014 3015 vm_page_set_validclean(m, base & PAGE_MASK, n); 3016 base += n; 3017 size -= n; 3018 n = PAGE_SIZE; 3019 } 3020 } 3021} 3022 3023/* 3024 * vfs_bio_clrbuf: 3025 * 3026 * clear a buffer. This routine essentially fakes an I/O, so we need 3027 * to clear BIO_ERROR and B_INVAL. 3028 * 3029 * Note that while we only theoretically need to clear through b_bcount, 3030 * we go ahead and clear through b_bufsize. 3031 */ 3032 3033void 3034vfs_bio_clrbuf(struct buf *bp) { 3035 int i, mask = 0; 3036 caddr_t sa, ea; 3037 if ((bp->b_flags & (B_VMIO | B_MALLOC)) == B_VMIO) { 3038 bp->b_flags &= ~B_INVAL; 3039 bp->b_ioflags &= ~BIO_ERROR; 3040 if( (bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 3041 (bp->b_offset & PAGE_MASK) == 0) { 3042 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 3043 if (((bp->b_pages[0]->flags & PG_ZERO) == 0) && 3044 ((bp->b_pages[0]->valid & mask) != mask)) { 3045 bzero(bp->b_data, bp->b_bufsize); 3046 } 3047 bp->b_pages[0]->valid |= mask; 3048 bp->b_resid = 0; 3049 return; 3050 } 3051 ea = sa = bp->b_data; 3052 for(i=0;i<bp->b_npages;i++,sa=ea) { 3053 int j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; 3054 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); 3055 ea = (caddr_t)(vm_offset_t)ulmin( 3056 (u_long)(vm_offset_t)ea, 3057 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); 3058 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 3059 if ((bp->b_pages[i]->valid & mask) == mask) 3060 continue; 3061 if ((bp->b_pages[i]->valid & mask) == 0) { 3062 if ((bp->b_pages[i]->flags & PG_ZERO) == 0) { 3063 bzero(sa, ea - sa); 3064 } 3065 } else { 3066 for (; sa < ea; sa += DEV_BSIZE, j++) { 3067 if (((bp->b_pages[i]->flags & PG_ZERO) == 0) && 3068 (bp->b_pages[i]->valid & (1<<j)) == 0) 3069 bzero(sa, DEV_BSIZE); 3070 } 3071 } 3072 bp->b_pages[i]->valid |= mask; 3073 vm_page_flag_clear(bp->b_pages[i], PG_ZERO); 3074 } 3075 bp->b_resid = 0; 3076 } else { 3077 clrbuf(bp); 3078 } 3079} 3080 3081/* 3082 * vm_hold_load_pages and vm_hold_unload pages get pages into 3083 * a buffers address space. The pages are anonymous and are 3084 * not associated with a file object. 3085 */ 3086void 3087vm_hold_load_pages(struct buf * bp, vm_offset_t from, vm_offset_t to) 3088{ 3089 vm_offset_t pg; 3090 vm_page_t p; 3091 int index; 3092 3093 to = round_page(to); 3094 from = round_page(from); 3095 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3096 3097 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3098 3099tryagain: 3100 3101 p = vm_page_alloc(kernel_object, 3102 ((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 3103 VM_ALLOC_NORMAL); 3104 if (!p) { 3105 vm_pageout_deficit += (to - from) >> PAGE_SHIFT; 3106 VM_WAIT; 3107 goto tryagain; 3108 } 3109 vm_page_wire(p); 3110 p->valid = VM_PAGE_BITS_ALL; 3111 vm_page_flag_clear(p, PG_ZERO); 3112 pmap_kenter(pg, VM_PAGE_TO_PHYS(p)); 3113 bp->b_pages[index] = p; 3114 vm_page_wakeup(p); 3115 } 3116 bp->b_npages = index; 3117} 3118 3119void 3120vm_hold_free_pages(struct buf * bp, vm_offset_t from, vm_offset_t to) 3121{ 3122 vm_offset_t pg; 3123 vm_page_t p; 3124 int index, newnpages; 3125 3126 from = round_page(from); 3127 to = round_page(to); 3128 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3129 3130 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3131 p = bp->b_pages[index]; 3132 if (p && (index < bp->b_npages)) { 3133 if (p->busy) { 3134 printf("vm_hold_free_pages: blkno: %d, lblkno: %d\n", 3135 bp->b_blkno, bp->b_lblkno); 3136 } 3137 bp->b_pages[index] = NULL; 3138 pmap_kremove(pg); 3139 vm_page_busy(p); 3140 vm_page_unwire(p, 0); 3141 vm_page_free(p); 3142 } 3143 } 3144 bp->b_npages = newnpages; 3145} 3146 3147 3148#include "opt_ddb.h" 3149#ifdef DDB 3150#include <ddb/ddb.h> 3151 3152DB_SHOW_COMMAND(buffer, db_show_buffer) 3153{ 3154 /* get args */ 3155 struct buf *bp = (struct buf *)addr; 3156 3157 if (!have_addr) { 3158 db_printf("usage: show buffer <addr>\n"); 3159 return; 3160 } 3161 3162 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS); 3163 db_printf("b_error = %d, b_bufsize = %ld, b_bcount = %ld, " 3164 "b_resid = %ld\nb_dev = (%d,%d), b_data = %p, " 3165 "b_blkno = %d, b_pblkno = %d\n", 3166 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 3167 major(bp->b_dev), minor(bp->b_dev), 3168 bp->b_data, bp->b_blkno, bp->b_pblkno); 3169 if (bp->b_npages) { 3170 int i; 3171 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 3172 for (i = 0; i < bp->b_npages; i++) { 3173 vm_page_t m; 3174 m = bp->b_pages[i]; 3175 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 3176 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 3177 if ((i + 1) < bp->b_npages) 3178 db_printf(","); 3179 } 3180 db_printf("\n"); 3181 } 3182} 3183#endif /* DDB */
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