vfs_cluster.c revision 111161
1/*- 2 * Copyright (c) 1993 3 * The Regents of the University of California. All rights reserved. 4 * Modifications/enhancements: 5 * Copyright (c) 1995 John S. Dyson. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgement: 17 * This product includes software developed by the University of 18 * California, Berkeley and its contributors. 19 * 4. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 * 35 * @(#)vfs_cluster.c 8.7 (Berkeley) 2/13/94 36 * $FreeBSD: head/sys/kern/vfs_cluster.c 111161 2003-02-20 03:26:11Z cognet $ 37 */ 38 39#include "opt_debug_cluster.h" 40 41#include <sys/param.h> 42#include <sys/systm.h> 43#include <sys/stdint.h> 44#include <sys/kernel.h> 45#include <sys/proc.h> 46#include <sys/bio.h> 47#include <sys/buf.h> 48#include <sys/vnode.h> 49#include <sys/malloc.h> 50#include <sys/mount.h> 51#include <sys/resourcevar.h> 52#include <sys/vmmeter.h> 53#include <vm/vm.h> 54#include <vm/vm_object.h> 55#include <vm/vm_page.h> 56#include <sys/sysctl.h> 57 58#if defined(CLUSTERDEBUG) 59static int rcluster= 0; 60SYSCTL_INT(_debug, OID_AUTO, rcluster, CTLFLAG_RW, &rcluster, 0, 61 "Debug VFS clustering code"); 62#endif 63 64static MALLOC_DEFINE(M_SEGMENT, "cluster_save buffer", "cluster_save buffer"); 65 66static struct cluster_save * 67 cluster_collectbufs(struct vnode *vp, struct buf *last_bp); 68static struct buf * 69 cluster_rbuild(struct vnode *vp, u_quad_t filesize, daddr_t lbn, 70 daddr_t blkno, long size, int run, struct buf *fbp); 71 72static int write_behind = 1; 73SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0, 74 "Cluster write-behind; 0: disable, 1: enable, 2: backed off"); 75 76/* Page expended to mark partially backed buffers */ 77extern vm_page_t bogus_page; 78 79/* 80 * Number of physical bufs (pbufs) this subsystem is allowed. 81 * Manipulated by vm_pager.c 82 */ 83extern int cluster_pbuf_freecnt; 84 85/* 86 * Maximum number of blocks for read-ahead. 87 */ 88#define MAXRA 32 89 90/* 91 * Read data to a buf, including read-ahead if we find this to be beneficial. 92 * cluster_read replaces bread. 93 */ 94int 95cluster_read(vp, filesize, lblkno, size, cred, totread, seqcount, bpp) 96 struct vnode *vp; 97 u_quad_t filesize; 98 daddr_t lblkno; 99 long size; 100 struct ucred *cred; 101 long totread; 102 int seqcount; 103 struct buf **bpp; 104{ 105 struct buf *bp, *rbp, *reqbp; 106 daddr_t blkno, origblkno; 107 int error, num_ra; 108 int i; 109 int maxra, racluster; 110 long origtotread; 111 112 error = 0; 113 114 /* 115 * Try to limit the amount of read-ahead by a few 116 * ad-hoc parameters. This needs work!!! 117 */ 118 racluster = vp->v_mount->mnt_iosize_max / size; 119 maxra = 2 * racluster + (totread / size); 120 if (maxra > MAXRA) 121 maxra = MAXRA; 122 if (maxra > nbuf/8) 123 maxra = nbuf/8; 124 125 /* 126 * get the requested block 127 */ 128 *bpp = reqbp = bp = getblk(vp, lblkno, size, 0, 0); 129 origblkno = lblkno; 130 origtotread = totread; 131 132 /* 133 * if it is in the cache, then check to see if the reads have been 134 * sequential. If they have, then try some read-ahead, otherwise 135 * back-off on prospective read-aheads. 136 */ 137 if (bp->b_flags & B_CACHE) { 138 if (!seqcount) { 139 return 0; 140 } else if ((bp->b_flags & B_RAM) == 0) { 141 return 0; 142 } else { 143 int s; 144 struct buf *tbp; 145 bp->b_flags &= ~B_RAM; 146 /* 147 * We do the spl here so that there is no window 148 * between the incore and the b_usecount increment 149 * below. We opt to keep the spl out of the loop 150 * for efficiency. 151 */ 152 s = splbio(); 153 VI_LOCK(vp); 154 for (i = 1; i < maxra; i++) { 155 /* 156 * Stop if the buffer does not exist or it 157 * is invalid (about to go away?) 158 */ 159 tbp = gbincore(vp, lblkno+i); 160 if (tbp == NULL || (tbp->b_flags & B_INVAL)) 161 break; 162 163 /* 164 * Set another read-ahead mark so we know 165 * to check again. 166 */ 167 if (((i % racluster) == (racluster - 1)) || 168 (i == (maxra - 1))) 169 tbp->b_flags |= B_RAM; 170 } 171 VI_UNLOCK(vp); 172 splx(s); 173 if (i >= maxra) { 174 return 0; 175 } 176 lblkno += i; 177 } 178 reqbp = bp = NULL; 179 } else { 180 off_t firstread = bp->b_offset; 181 182 KASSERT(bp->b_offset != NOOFFSET, 183 ("cluster_read: no buffer offset")); 184 if (firstread + totread > filesize) 185 totread = filesize - firstread; 186 if (totread > size) { 187 int nblks = 0; 188 int ncontigafter; 189 while (totread > 0) { 190 nblks++; 191 totread -= size; 192 } 193 if (nblks == 1) 194 goto single_block_read; 195 if (nblks > racluster) 196 nblks = racluster; 197 198 error = VOP_BMAP(vp, lblkno, NULL, 199 &blkno, &ncontigafter, NULL); 200 if (error) 201 goto single_block_read; 202 if (blkno == -1) 203 goto single_block_read; 204 if (ncontigafter == 0) 205 goto single_block_read; 206 if (ncontigafter + 1 < nblks) 207 nblks = ncontigafter + 1; 208 209 bp = cluster_rbuild(vp, filesize, lblkno, 210 blkno, size, nblks, bp); 211 lblkno += (bp->b_bufsize / size); 212 } else { 213single_block_read: 214 /* 215 * if it isn't in the cache, then get a chunk from 216 * disk if sequential, otherwise just get the block. 217 */ 218 bp->b_flags |= B_RAM; 219 bp->b_iocmd = BIO_READ; 220 lblkno += 1; 221 } 222 } 223 224 /* 225 * if we have been doing sequential I/O, then do some read-ahead 226 */ 227 rbp = NULL; 228 if (seqcount && (lblkno < (origblkno + seqcount))) { 229 /* 230 * we now build the read-ahead buffer if it is desirable. 231 */ 232 if (((u_quad_t)(lblkno + 1) * size) <= filesize && 233 !(error = VOP_BMAP(vp, lblkno, NULL, &blkno, &num_ra, NULL)) && 234 blkno != -1) { 235 int nblksread; 236 int ntoread = num_ra + 1; 237 nblksread = (origtotread + size - 1) / size; 238 if (seqcount < nblksread) 239 seqcount = nblksread; 240 if (seqcount < ntoread) 241 ntoread = seqcount; 242 if (num_ra) { 243 rbp = cluster_rbuild(vp, filesize, lblkno, 244 blkno, size, ntoread, NULL); 245 } else { 246 rbp = getblk(vp, lblkno, size, 0, 0); 247 rbp->b_flags |= B_ASYNC | B_RAM; 248 rbp->b_iocmd = BIO_READ; 249 rbp->b_blkno = blkno; 250 } 251 } 252 } 253 254 /* 255 * handle the synchronous read 256 */ 257 if (bp) { 258#if defined(CLUSTERDEBUG) 259 if (rcluster) 260 printf("S(%ld,%ld,%d) ", 261 (long)bp->b_lblkno, bp->b_bcount, seqcount); 262#endif 263 if ((bp->b_flags & B_CLUSTER) == 0) { 264 vfs_busy_pages(bp, 0); 265 } 266 bp->b_flags &= ~B_INVAL; 267 bp->b_ioflags &= ~BIO_ERROR; 268 if ((bp->b_flags & B_ASYNC) || bp->b_iodone != NULL) 269 BUF_KERNPROC(bp); 270 error = VOP_STRATEGY(vp, bp); 271 curproc->p_stats->p_ru.ru_inblock++; 272 } 273 274 /* 275 * and if we have read-aheads, do them too 276 */ 277 if (rbp) { 278 if (error) { 279 rbp->b_flags &= ~B_ASYNC; 280 brelse(rbp); 281 } else if (rbp->b_flags & B_CACHE) { 282 rbp->b_flags &= ~B_ASYNC; 283 bqrelse(rbp); 284 } else { 285#if defined(CLUSTERDEBUG) 286 if (rcluster) { 287 if (bp) 288 printf("A+"); 289 else 290 printf("A"); 291 printf("(%jd,%jd,%jd,%jd) ", 292 (intmax_t)rbp->b_lblkno, 293 (intmax_t)rbp->b_bcount, 294 (intmax_t)(rbp->b_lblkno - origblkno), 295 (intmax_t)seqcount); 296 } 297#endif 298 299 if ((rbp->b_flags & B_CLUSTER) == 0) { 300 vfs_busy_pages(rbp, 0); 301 } 302 rbp->b_flags &= ~B_INVAL; 303 rbp->b_ioflags &= ~BIO_ERROR; 304 if ((rbp->b_flags & B_ASYNC) || rbp->b_iodone != NULL) 305 BUF_KERNPROC(rbp); 306 (void) VOP_STRATEGY(vp, rbp); 307 curproc->p_stats->p_ru.ru_inblock++; 308 } 309 } 310 if (reqbp) 311 return (bufwait(reqbp)); 312 else 313 return (error); 314} 315 316/* 317 * If blocks are contiguous on disk, use this to provide clustered 318 * read ahead. We will read as many blocks as possible sequentially 319 * and then parcel them up into logical blocks in the buffer hash table. 320 */ 321static struct buf * 322cluster_rbuild(vp, filesize, lbn, blkno, size, run, fbp) 323 struct vnode *vp; 324 u_quad_t filesize; 325 daddr_t lbn; 326 daddr_t blkno; 327 long size; 328 int run; 329 struct buf *fbp; 330{ 331 struct buf *bp, *tbp; 332 daddr_t bn; 333 int i, inc, j; 334 335 GIANT_REQUIRED; 336 337 KASSERT(size == vp->v_mount->mnt_stat.f_iosize, 338 ("cluster_rbuild: size %ld != filesize %ld\n", 339 size, vp->v_mount->mnt_stat.f_iosize)); 340 341 /* 342 * avoid a division 343 */ 344 while ((u_quad_t) size * (lbn + run) > filesize) { 345 --run; 346 } 347 348 if (fbp) { 349 tbp = fbp; 350 tbp->b_iocmd = BIO_READ; 351 } else { 352 tbp = getblk(vp, lbn, size, 0, 0); 353 if (tbp->b_flags & B_CACHE) 354 return tbp; 355 tbp->b_flags |= B_ASYNC | B_RAM; 356 tbp->b_iocmd = BIO_READ; 357 } 358 359 tbp->b_blkno = blkno; 360 if( (tbp->b_flags & B_MALLOC) || 361 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1) ) 362 return tbp; 363 364 bp = trypbuf(&cluster_pbuf_freecnt); 365 if (bp == 0) 366 return tbp; 367 368 /* 369 * We are synthesizing a buffer out of vm_page_t's, but 370 * if the block size is not page aligned then the starting 371 * address may not be either. Inherit the b_data offset 372 * from the original buffer. 373 */ 374 bp->b_data = (char *)((vm_offset_t)bp->b_data | 375 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 376 bp->b_flags = B_ASYNC | B_CLUSTER | B_VMIO; 377 bp->b_iocmd = BIO_READ; 378 bp->b_iodone = cluster_callback; 379 bp->b_blkno = blkno; 380 bp->b_lblkno = lbn; 381 bp->b_offset = tbp->b_offset; 382 KASSERT(bp->b_offset != NOOFFSET, ("cluster_rbuild: no buffer offset")); 383 pbgetvp(vp, bp); 384 385 TAILQ_INIT(&bp->b_cluster.cluster_head); 386 387 bp->b_bcount = 0; 388 bp->b_bufsize = 0; 389 bp->b_npages = 0; 390 391 inc = btodb(size); 392 for (bn = blkno, i = 0; i < run; ++i, bn += inc) { 393 if (i != 0) { 394 if ((bp->b_npages * PAGE_SIZE) + 395 round_page(size) > vp->v_mount->mnt_iosize_max) { 396 break; 397 } 398 399 /* 400 * Shortcut some checks and try to avoid buffers that 401 * would block in the lock. The same checks have to 402 * be made again after we officially get the buffer. 403 */ 404 if ((tbp = incore(vp, lbn + i)) != NULL && 405 (tbp->b_flags & B_INVAL) == 0) { 406 if (BUF_LOCK(tbp, LK_EXCLUSIVE | LK_NOWAIT)) 407 break; 408 BUF_UNLOCK(tbp); 409 410 for (j = 0; j < tbp->b_npages; j++) { 411 if (tbp->b_pages[j]->valid) 412 break; 413 } 414 415 if (j != tbp->b_npages) 416 break; 417 418 if (tbp->b_bcount != size) 419 break; 420 } 421 422 tbp = getblk(vp, lbn + i, size, 0, 0); 423 424 /* 425 * Stop scanning if the buffer is fully valid 426 * (marked B_CACHE), or locked (may be doing a 427 * background write), or if the buffer is not 428 * VMIO backed. The clustering code can only deal 429 * with VMIO-backed buffers. 430 */ 431 if ((tbp->b_flags & (B_CACHE|B_LOCKED)) || 432 (tbp->b_flags & B_VMIO) == 0) { 433 bqrelse(tbp); 434 break; 435 } 436 437 /* 438 * The buffer must be completely invalid in order to 439 * take part in the cluster. If it is partially valid 440 * then we stop. 441 */ 442 for (j = 0;j < tbp->b_npages; j++) { 443 if (tbp->b_pages[j]->valid) 444 break; 445 } 446 if (j != tbp->b_npages) { 447 bqrelse(tbp); 448 break; 449 } 450 451 /* 452 * Set a read-ahead mark as appropriate 453 */ 454 if ((fbp && (i == 1)) || (i == (run - 1))) 455 tbp->b_flags |= B_RAM; 456 457 /* 458 * Set the buffer up for an async read (XXX should 459 * we do this only if we do not wind up brelse()ing?). 460 * Set the block number if it isn't set, otherwise 461 * if it is make sure it matches the block number we 462 * expect. 463 */ 464 tbp->b_flags |= B_ASYNC; 465 tbp->b_iocmd = BIO_READ; 466 if (tbp->b_blkno == tbp->b_lblkno) { 467 tbp->b_blkno = bn; 468 } else if (tbp->b_blkno != bn) { 469 brelse(tbp); 470 break; 471 } 472 } 473 /* 474 * XXX fbp from caller may not be B_ASYNC, but we are going 475 * to biodone() it in cluster_callback() anyway 476 */ 477 BUF_KERNPROC(tbp); 478 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head, 479 tbp, b_cluster.cluster_entry); 480 vm_page_lock_queues(); 481 for (j = 0; j < tbp->b_npages; j += 1) { 482 vm_page_t m; 483 m = tbp->b_pages[j]; 484 vm_page_io_start(m); 485 vm_object_pip_add(m->object, 1); 486 if ((bp->b_npages == 0) || 487 (bp->b_pages[bp->b_npages-1] != m)) { 488 bp->b_pages[bp->b_npages] = m; 489 bp->b_npages++; 490 } 491 if ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) 492 tbp->b_pages[j] = bogus_page; 493 } 494 vm_page_unlock_queues(); 495 /* 496 * XXX shouldn't this be += size for both, like in 497 * cluster_wbuild()? 498 * 499 * Don't inherit tbp->b_bufsize as it may be larger due to 500 * a non-page-aligned size. Instead just aggregate using 501 * 'size'. 502 */ 503 if (tbp->b_bcount != size) 504 printf("warning: tbp->b_bcount wrong %ld vs %ld\n", tbp->b_bcount, size); 505 if (tbp->b_bufsize != size) 506 printf("warning: tbp->b_bufsize wrong %ld vs %ld\n", tbp->b_bufsize, size); 507 bp->b_bcount += size; 508 bp->b_bufsize += size; 509 } 510 511 /* 512 * Fully valid pages in the cluster are already good and do not need 513 * to be re-read from disk. Replace the page with bogus_page 514 */ 515 for (j = 0; j < bp->b_npages; j++) { 516 if ((bp->b_pages[j]->valid & VM_PAGE_BITS_ALL) == 517 VM_PAGE_BITS_ALL) { 518 bp->b_pages[j] = bogus_page; 519 } 520 } 521 if (bp->b_bufsize > bp->b_kvasize) 522 panic("cluster_rbuild: b_bufsize(%ld) > b_kvasize(%d)\n", 523 bp->b_bufsize, bp->b_kvasize); 524 bp->b_kvasize = bp->b_bufsize; 525 526 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 527 (vm_page_t *)bp->b_pages, bp->b_npages); 528 return (bp); 529} 530 531/* 532 * Cleanup after a clustered read or write. 533 * This is complicated by the fact that any of the buffers might have 534 * extra memory (if there were no empty buffer headers at allocbuf time) 535 * that we will need to shift around. 536 */ 537void 538cluster_callback(bp) 539 struct buf *bp; 540{ 541 struct buf *nbp, *tbp; 542 int error = 0; 543 544 GIANT_REQUIRED; 545 546 /* 547 * Must propogate errors to all the components. 548 */ 549 if (bp->b_ioflags & BIO_ERROR) 550 error = bp->b_error; 551 552 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages); 553 /* 554 * Move memory from the large cluster buffer into the component 555 * buffers and mark IO as done on these. 556 */ 557 for (tbp = TAILQ_FIRST(&bp->b_cluster.cluster_head); 558 tbp; tbp = nbp) { 559 nbp = TAILQ_NEXT(&tbp->b_cluster, cluster_entry); 560 if (error) { 561 tbp->b_ioflags |= BIO_ERROR; 562 tbp->b_error = error; 563 } else { 564 tbp->b_dirtyoff = tbp->b_dirtyend = 0; 565 tbp->b_flags &= ~B_INVAL; 566 tbp->b_ioflags &= ~BIO_ERROR; 567 /* 568 * XXX the bdwrite()/bqrelse() issued during 569 * cluster building clears B_RELBUF (see bqrelse() 570 * comment). If direct I/O was specified, we have 571 * to restore it here to allow the buffer and VM 572 * to be freed. 573 */ 574 if (tbp->b_flags & B_DIRECT) 575 tbp->b_flags |= B_RELBUF; 576 } 577 bufdone(tbp); 578 } 579 relpbuf(bp, &cluster_pbuf_freecnt); 580} 581 582/* 583 * cluster_wbuild_wb: 584 * 585 * Implement modified write build for cluster. 586 * 587 * write_behind = 0 write behind disabled 588 * write_behind = 1 write behind normal (default) 589 * write_behind = 2 write behind backed-off 590 */ 591 592static __inline int 593cluster_wbuild_wb(struct vnode *vp, long size, daddr_t start_lbn, int len) 594{ 595 int r = 0; 596 597 switch(write_behind) { 598 case 2: 599 if (start_lbn < len) 600 break; 601 start_lbn -= len; 602 /* FALLTHROUGH */ 603 case 1: 604 r = cluster_wbuild(vp, size, start_lbn, len); 605 /* FALLTHROUGH */ 606 default: 607 /* FALLTHROUGH */ 608 break; 609 } 610 return(r); 611} 612 613/* 614 * Do clustered write for FFS. 615 * 616 * Three cases: 617 * 1. Write is not sequential (write asynchronously) 618 * Write is sequential: 619 * 2. beginning of cluster - begin cluster 620 * 3. middle of a cluster - add to cluster 621 * 4. end of a cluster - asynchronously write cluster 622 */ 623void 624cluster_write(bp, filesize, seqcount) 625 struct buf *bp; 626 u_quad_t filesize; 627 int seqcount; 628{ 629 struct vnode *vp; 630 daddr_t lbn; 631 int maxclen, cursize; 632 int lblocksize; 633 int async; 634 635 vp = bp->b_vp; 636 if (vp->v_type == VREG) { 637 async = vp->v_mount->mnt_flag & MNT_ASYNC; 638 lblocksize = vp->v_mount->mnt_stat.f_iosize; 639 } else { 640 async = 0; 641 lblocksize = bp->b_bufsize; 642 } 643 lbn = bp->b_lblkno; 644 KASSERT(bp->b_offset != NOOFFSET, ("cluster_write: no buffer offset")); 645 646 /* Initialize vnode to beginning of file. */ 647 if (lbn == 0) 648 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0; 649 650 if (vp->v_clen == 0 || lbn != vp->v_lastw + 1 || 651 (bp->b_blkno != vp->v_lasta + btodb(lblocksize))) { 652 maxclen = vp->v_mount->mnt_iosize_max / lblocksize - 1; 653 if (vp->v_clen != 0) { 654 /* 655 * Next block is not sequential. 656 * 657 * If we are not writing at end of file, the process 658 * seeked to another point in the file since its last 659 * write, or we have reached our maximum cluster size, 660 * then push the previous cluster. Otherwise try 661 * reallocating to make it sequential. 662 * 663 * Change to algorithm: only push previous cluster if 664 * it was sequential from the point of view of the 665 * seqcount heuristic, otherwise leave the buffer 666 * intact so we can potentially optimize the I/O 667 * later on in the buf_daemon or update daemon 668 * flush. 669 */ 670 cursize = vp->v_lastw - vp->v_cstart + 1; 671 if (((u_quad_t) bp->b_offset + lblocksize) != filesize || 672 lbn != vp->v_lastw + 1 || vp->v_clen <= cursize) { 673 if (!async && seqcount > 0) { 674 cluster_wbuild_wb(vp, lblocksize, 675 vp->v_cstart, cursize); 676 } 677 } else { 678 struct buf **bpp, **endbp; 679 struct cluster_save *buflist; 680 681 buflist = cluster_collectbufs(vp, bp); 682 endbp = &buflist->bs_children 683 [buflist->bs_nchildren - 1]; 684 if (VOP_REALLOCBLKS(vp, buflist)) { 685 /* 686 * Failed, push the previous cluster 687 * if *really* writing sequentially 688 * in the logical file (seqcount > 1), 689 * otherwise delay it in the hopes that 690 * the low level disk driver can 691 * optimize the write ordering. 692 */ 693 for (bpp = buflist->bs_children; 694 bpp < endbp; bpp++) 695 brelse(*bpp); 696 free(buflist, M_SEGMENT); 697 if (seqcount > 1) { 698 cluster_wbuild_wb(vp, 699 lblocksize, vp->v_cstart, 700 cursize); 701 } 702 } else { 703 /* 704 * Succeeded, keep building cluster. 705 */ 706 for (bpp = buflist->bs_children; 707 bpp <= endbp; bpp++) 708 bdwrite(*bpp); 709 free(buflist, M_SEGMENT); 710 vp->v_lastw = lbn; 711 vp->v_lasta = bp->b_blkno; 712 return; 713 } 714 } 715 } 716 /* 717 * Consider beginning a cluster. If at end of file, make 718 * cluster as large as possible, otherwise find size of 719 * existing cluster. 720 */ 721 if ((vp->v_type == VREG) && 722 ((u_quad_t) bp->b_offset + lblocksize) != filesize && 723 (bp->b_blkno == bp->b_lblkno) && 724 (VOP_BMAP(vp, lbn, NULL, &bp->b_blkno, &maxclen, NULL) || 725 bp->b_blkno == -1)) { 726 bawrite(bp); 727 vp->v_clen = 0; 728 vp->v_lasta = bp->b_blkno; 729 vp->v_cstart = lbn + 1; 730 vp->v_lastw = lbn; 731 return; 732 } 733 vp->v_clen = maxclen; 734 if (!async && maxclen == 0) { /* I/O not contiguous */ 735 vp->v_cstart = lbn + 1; 736 bawrite(bp); 737 } else { /* Wait for rest of cluster */ 738 vp->v_cstart = lbn; 739 bdwrite(bp); 740 } 741 } else if (lbn == vp->v_cstart + vp->v_clen) { 742 /* 743 * At end of cluster, write it out if seqcount tells us we 744 * are operating sequentially, otherwise let the buf or 745 * update daemon handle it. 746 */ 747 bdwrite(bp); 748 if (seqcount > 1) 749 cluster_wbuild_wb(vp, lblocksize, vp->v_cstart, vp->v_clen + 1); 750 vp->v_clen = 0; 751 vp->v_cstart = lbn + 1; 752 } else if (vm_page_count_severe()) { 753 /* 754 * We are low on memory, get it going NOW 755 */ 756 bawrite(bp); 757 } else { 758 /* 759 * In the middle of a cluster, so just delay the I/O for now. 760 */ 761 bdwrite(bp); 762 } 763 vp->v_lastw = lbn; 764 vp->v_lasta = bp->b_blkno; 765} 766 767 768/* 769 * This is an awful lot like cluster_rbuild...wish they could be combined. 770 * The last lbn argument is the current block on which I/O is being 771 * performed. Check to see that it doesn't fall in the middle of 772 * the current block (if last_bp == NULL). 773 */ 774int 775cluster_wbuild(vp, size, start_lbn, len) 776 struct vnode *vp; 777 long size; 778 daddr_t start_lbn; 779 int len; 780{ 781 struct buf *bp, *tbp; 782 int i, j, s; 783 int totalwritten = 0; 784 int dbsize = btodb(size); 785 786 GIANT_REQUIRED; 787 788 while (len > 0) { 789 s = splbio(); 790 /* 791 * If the buffer is not delayed-write (i.e. dirty), or it 792 * is delayed-write but either locked or inval, it cannot 793 * partake in the clustered write. 794 */ 795 if (((tbp = incore(vp, start_lbn)) == NULL) || 796 ((tbp->b_flags & (B_LOCKED | B_INVAL | B_DELWRI)) != B_DELWRI) || 797 BUF_LOCK(tbp, LK_EXCLUSIVE | LK_NOWAIT)) { 798 ++start_lbn; 799 --len; 800 splx(s); 801 continue; 802 } 803 bremfree(tbp); 804 tbp->b_flags &= ~B_DONE; 805 splx(s); 806 807 /* 808 * Extra memory in the buffer, punt on this buffer. 809 * XXX we could handle this in most cases, but we would 810 * have to push the extra memory down to after our max 811 * possible cluster size and then potentially pull it back 812 * up if the cluster was terminated prematurely--too much 813 * hassle. 814 */ 815 if (((tbp->b_flags & (B_CLUSTEROK | B_MALLOC | B_VMIO)) != 816 (B_CLUSTEROK | B_VMIO)) || 817 (tbp->b_bcount != tbp->b_bufsize) || 818 (tbp->b_bcount != size) || 819 (len == 1) || 820 ((bp = getpbuf(&cluster_pbuf_freecnt)) == NULL)) { 821 totalwritten += tbp->b_bufsize; 822 bawrite(tbp); 823 ++start_lbn; 824 --len; 825 continue; 826 } 827 828 /* 829 * We got a pbuf to make the cluster in. 830 * so initialise it. 831 */ 832 TAILQ_INIT(&bp->b_cluster.cluster_head); 833 bp->b_bcount = 0; 834 bp->b_magic = tbp->b_magic; 835 bp->b_op = tbp->b_op; 836 bp->b_bufsize = 0; 837 bp->b_npages = 0; 838 if (tbp->b_wcred != NOCRED) 839 bp->b_wcred = crhold(tbp->b_wcred); 840 841 bp->b_blkno = tbp->b_blkno; 842 bp->b_lblkno = tbp->b_lblkno; 843 bp->b_offset = tbp->b_offset; 844 845 /* 846 * We are synthesizing a buffer out of vm_page_t's, but 847 * if the block size is not page aligned then the starting 848 * address may not be either. Inherit the b_data offset 849 * from the original buffer. 850 */ 851 bp->b_data = (char *)((vm_offset_t)bp->b_data | 852 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 853 bp->b_flags |= B_CLUSTER | 854 (tbp->b_flags & (B_VMIO | B_NEEDCOMMIT | B_NOWDRAIN)); 855 bp->b_iodone = cluster_callback; 856 pbgetvp(vp, bp); 857 /* 858 * From this location in the file, scan forward to see 859 * if there are buffers with adjacent data that need to 860 * be written as well. 861 */ 862 for (i = 0; i < len; ++i, ++start_lbn) { 863 if (i != 0) { /* If not the first buffer */ 864 s = splbio(); 865 /* 866 * If the adjacent data is not even in core it 867 * can't need to be written. 868 */ 869 if ((tbp = incore(vp, start_lbn)) == NULL) { 870 splx(s); 871 break; 872 } 873 874 /* 875 * If it IS in core, but has different 876 * characteristics, or is locked (which 877 * means it could be undergoing a background 878 * I/O or be in a weird state), then don't 879 * cluster with it. 880 */ 881 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK | 882 B_INVAL | B_DELWRI | B_NEEDCOMMIT)) 883 != (B_DELWRI | B_CLUSTEROK | 884 (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) || 885 (tbp->b_flags & B_LOCKED) || 886 tbp->b_wcred != bp->b_wcred || 887 BUF_LOCK(tbp, LK_EXCLUSIVE | LK_NOWAIT)) { 888 splx(s); 889 break; 890 } 891 892 /* 893 * Check that the combined cluster 894 * would make sense with regard to pages 895 * and would not be too large 896 */ 897 if ((tbp->b_bcount != size) || 898 ((bp->b_blkno + (dbsize * i)) != 899 tbp->b_blkno) || 900 ((tbp->b_npages + bp->b_npages) > 901 (vp->v_mount->mnt_iosize_max / PAGE_SIZE))) { 902 BUF_UNLOCK(tbp); 903 splx(s); 904 break; 905 } 906 /* 907 * Ok, it's passed all the tests, 908 * so remove it from the free list 909 * and mark it busy. We will use it. 910 */ 911 bremfree(tbp); 912 tbp->b_flags &= ~B_DONE; 913 splx(s); 914 } /* end of code for non-first buffers only */ 915 /* check for latent dependencies to be handled */ 916 if ((LIST_FIRST(&tbp->b_dep)) != NULL) 917 buf_start(tbp); 918 /* 919 * If the IO is via the VM then we do some 920 * special VM hackery (yuck). Since the buffer's 921 * block size may not be page-aligned it is possible 922 * for a page to be shared between two buffers. We 923 * have to get rid of the duplication when building 924 * the cluster. 925 */ 926 if (tbp->b_flags & B_VMIO) { 927 vm_page_t m; 928 929 if (i != 0) { /* if not first buffer */ 930 for (j = 0; j < tbp->b_npages; j += 1) { 931 m = tbp->b_pages[j]; 932 if (m->flags & PG_BUSY) { 933 bqrelse(tbp); 934 goto finishcluster; 935 } 936 } 937 } 938 vm_page_lock_queues(); 939 for (j = 0; j < tbp->b_npages; j += 1) { 940 m = tbp->b_pages[j]; 941 vm_page_io_start(m); 942 vm_object_pip_add(m->object, 1); 943 if ((bp->b_npages == 0) || 944 (bp->b_pages[bp->b_npages - 1] != m)) { 945 bp->b_pages[bp->b_npages] = m; 946 bp->b_npages++; 947 } 948 } 949 vm_page_unlock_queues(); 950 } 951 bp->b_bcount += size; 952 bp->b_bufsize += size; 953 954 s = splbio(); 955 bundirty(tbp); 956 tbp->b_flags &= ~B_DONE; 957 tbp->b_ioflags &= ~BIO_ERROR; 958 tbp->b_flags |= B_ASYNC; 959 tbp->b_iocmd = BIO_WRITE; 960 reassignbuf(tbp, tbp->b_vp); /* put on clean list */ 961 VI_LOCK(tbp->b_vp); 962 ++tbp->b_vp->v_numoutput; 963 VI_UNLOCK(tbp->b_vp); 964 splx(s); 965 BUF_KERNPROC(tbp); 966 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head, 967 tbp, b_cluster.cluster_entry); 968 } 969 finishcluster: 970 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 971 (vm_page_t *) bp->b_pages, bp->b_npages); 972 if (bp->b_bufsize > bp->b_kvasize) 973 panic( 974 "cluster_wbuild: b_bufsize(%ld) > b_kvasize(%d)\n", 975 bp->b_bufsize, bp->b_kvasize); 976 bp->b_kvasize = bp->b_bufsize; 977 totalwritten += bp->b_bufsize; 978 bp->b_dirtyoff = 0; 979 bp->b_dirtyend = bp->b_bufsize; 980 bawrite(bp); 981 982 len -= i; 983 } 984 return totalwritten; 985} 986 987/* 988 * Collect together all the buffers in a cluster. 989 * Plus add one additional buffer. 990 */ 991static struct cluster_save * 992cluster_collectbufs(vp, last_bp) 993 struct vnode *vp; 994 struct buf *last_bp; 995{ 996 struct cluster_save *buflist; 997 struct buf *bp; 998 daddr_t lbn; 999 int i, len; 1000 1001 len = vp->v_lastw - vp->v_cstart + 1; 1002 buflist = malloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist), 1003 M_SEGMENT, M_WAITOK); 1004 buflist->bs_nchildren = 0; 1005 buflist->bs_children = (struct buf **) (buflist + 1); 1006 for (lbn = vp->v_cstart, i = 0; i < len; lbn++, i++) { 1007 (void) bread(vp, lbn, last_bp->b_bcount, NOCRED, &bp); 1008 buflist->bs_children[i] = bp; 1009 if (bp->b_blkno == bp->b_lblkno) 1010 VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno, 1011 NULL, NULL); 1012 } 1013 buflist->bs_children[i] = bp = last_bp; 1014 if (bp->b_blkno == bp->b_lblkno) 1015 VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno, 1016 NULL, NULL); 1017 buflist->bs_nchildren = i + 1; 1018 return (buflist); 1019} 1020