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