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sys/kern/vfs_cluster.c
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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/kernel.h> 44 #include <sys/proc.h> 45 #include <sys/buf.h> 46 #include <sys/vnode.h> 47 #include <sys/malloc.h> 48 #include <sys/mount.h> 49 #include <sys/resourcevar.h> 50 #include <sys/vmmeter.h> 51 #include <vm/vm.h> 52 #include <vm/vm_object.h> 53 #include <vm/vm_page.h> 54 #include <sys/sysctl.h> 55 56 #if defined(CLUSTERDEBUG) 57 #include <sys/sysctl.h> 58 static int rcluster= 0; 59 SYSCTL_INT(_debug, OID_AUTO, rcluster, CTLFLAG_RW, &rcluster, 0, ""); 60 #endif 61 62 static MALLOC_DEFINE(M_SEGMENT, "cluster_save buffer", "cluster_save buffer"); 63 64 static struct cluster_save * 65 cluster_collectbufs __P((struct vnode *vp, struct buf *last_bp)); 66 static struct buf * 67 cluster_rbuild __P((struct vnode *vp, u_quad_t filesize, daddr_t lbn, 68 daddr_t blkno, long size, int run, struct buf *fbp)); 69 70 static int write_behind = 1; 71 SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0, ""); 72 73 extern vm_page_t bogus_page; 74 75 extern int cluster_pbuf_freecnt; 76 77 /* 78 * Maximum number of blocks for read-ahead. 79 */ 80 #define MAXRA 32 81 82 /* 83 * This replaces bread. 84 */ 85 int 86 cluster_read(vp, filesize, lblkno, size, cred, totread, seqcount, bpp) 87 struct vnode *vp; 88 u_quad_t filesize; 89 daddr_t lblkno; 90 long size; 91 struct ucred *cred; 92 long totread; 93 int seqcount; 94 struct buf **bpp; 95 { 96 struct buf *bp, *rbp, *reqbp; 97 daddr_t blkno, origblkno; 98 int error, num_ra; 99 int i; 100 int maxra, racluster; 101 long origtotread; 102 103 error = 0; 104 105 /* 106 * Try to limit the amount of read-ahead by a few 107 * ad-hoc parameters. This needs work!!! 108 */ 109 racluster = vp->v_mount->mnt_iosize_max / size; 110 maxra = 2 * racluster + (totread / size); 111 if (maxra > MAXRA) 112 maxra = MAXRA; 113 if (maxra > nbuf/8) 114 maxra = nbuf/8; 115 116 /* 117 * get the requested block 118 */ 119 *bpp = reqbp = bp = getblk(vp, lblkno, size, 0, 0); 120 origblkno = lblkno; 121 origtotread = totread; 122 123 /* 124 * if it is in the cache, then check to see if the reads have been 125 * sequential. If they have, then try some read-ahead, otherwise 126 * back-off on prospective read-aheads. 127 */ 128 if (bp->b_flags & B_CACHE) { 129 if (!seqcount) { 130 return 0; 131 } else if ((bp->b_flags & B_RAM) == 0) { 132 return 0; 133 } else { 134 int s; 135 struct buf *tbp; 136 bp->b_flags &= ~B_RAM; 137 /* 138 * We do the spl here so that there is no window 139 * between the incore and the b_usecount increment 140 * below. We opt to keep the spl out of the loop 141 * for efficiency. 142 */ 143 s = splbio(); 144 for (i = 1; i < maxra; i++) { 145 146 if (!(tbp = incore(vp, lblkno+i))) { 147 break; 148 } 149 150 /* 151 * Set another read-ahead mark so we know 152 * to check again. 153 */ 154 if (((i % racluster) == (racluster - 1)) || 155 (i == (maxra - 1))) 156 tbp->b_flags |= B_RAM; 157 } 158 splx(s); 159 if (i >= maxra) { 160 return 0; 161 } 162 lblkno += i; 163 } 164 reqbp = bp = NULL; 165 } else { 166 off_t firstread = bp->b_offset; 167 168 KASSERT(bp->b_offset != NOOFFSET, 169 ("cluster_read: no buffer offset")); 170 if (firstread + totread > filesize) 171 totread = filesize - firstread; 172 if (totread > size) { 173 int nblks = 0; 174 int ncontigafter; 175 while (totread > 0) { 176 nblks++; 177 totread -= size; 178 } 179 if (nblks == 1) 180 goto single_block_read; 181 if (nblks > racluster) 182 nblks = racluster; 183 184 error = VOP_BMAP(vp, lblkno, NULL, 185 &blkno, &ncontigafter, NULL); 186 if (error) 187 goto single_block_read; 188 if (blkno == -1) 189 goto single_block_read; 190 if (ncontigafter == 0) 191 goto single_block_read; 192 if (ncontigafter + 1 < nblks) 193 nblks = ncontigafter + 1; 194 195 bp = cluster_rbuild(vp, filesize, lblkno, 196 blkno, size, nblks, bp); 197 lblkno += (bp->b_bufsize / size); 198 } else { 199 single_block_read: 200 /* 201 * if it isn't in the cache, then get a chunk from 202 * disk if sequential, otherwise just get the block. 203 */ 204 bp->b_flags |= B_READ | B_RAM; 205 lblkno += 1; 206 } 207 } 208 209 /* 210 * if we have been doing sequential I/O, then do some read-ahead 211 */ 212 rbp = NULL; 213 if (seqcount && (lblkno < (origblkno + seqcount))) { 214 /* 215 * we now build the read-ahead buffer if it is desirable. 216 */ 217 if (((u_quad_t)(lblkno + 1) * size) <= filesize && 218 !(error = VOP_BMAP(vp, lblkno, NULL, &blkno, &num_ra, NULL)) && 219 blkno != -1) { 220 int nblksread; 221 int ntoread = num_ra + 1; 222 nblksread = (origtotread + size - 1) / size; 223 if (seqcount < nblksread) 224 seqcount = nblksread; 225 if (seqcount < ntoread) 226 ntoread = seqcount; 227 if (num_ra) { 228 rbp = cluster_rbuild(vp, filesize, lblkno, 229 blkno, size, ntoread, NULL); 230 } else { 231 rbp = getblk(vp, lblkno, size, 0, 0); 232 rbp->b_flags |= B_READ | B_ASYNC | B_RAM; 233 rbp->b_blkno = blkno; 234 } 235 } 236 } 237 238 /* 239 * handle the synchronous read 240 */ 241 if (bp) { 242 #if defined(CLUSTERDEBUG) 243 if (rcluster) 244 printf("S(%ld,%ld,%d) ", 245 (long)bp->b_lblkno, bp->b_bcount, seqcount); 246 #endif 247 if ((bp->b_flags & B_CLUSTER) == 0) { 248 vfs_busy_pages(bp, 0); 249 } 250 bp->b_flags &= ~(B_ERROR|B_INVAL); 251 if (bp->b_flags & (B_ASYNC|B_CALL)) 252 BUF_KERNPROC(bp); 253 error = VOP_STRATEGY(vp, bp); 254 curproc->p_stats->p_ru.ru_inblock++; 255 } 256 257 /* 258 * and if we have read-aheads, do them too 259 */ 260 if (rbp) { 261 if (error) { 262 rbp->b_flags &= ~(B_ASYNC | B_READ); 263 brelse(rbp); 264 } else if (rbp->b_flags & B_CACHE) { 265 rbp->b_flags &= ~(B_ASYNC | B_READ); 266 bqrelse(rbp); 267 } else { 268 #if defined(CLUSTERDEBUG) 269 if (rcluster) { 270 if (bp) 271 printf("A+(%ld,%ld,%ld,%d) ", 272 (long)rbp->b_lblkno, rbp->b_bcount, 273 (long)(rbp->b_lblkno - origblkno), 274 seqcount); 275 else 276 printf("A(%ld,%ld,%ld,%d) ", 277 (long)rbp->b_lblkno, rbp->b_bcount, 278 (long)(rbp->b_lblkno - origblkno), 279 seqcount); 280 } 281 #endif 282 283 if ((rbp->b_flags & B_CLUSTER) == 0) { 284 vfs_busy_pages(rbp, 0); 285 } 286 rbp->b_flags &= ~(B_ERROR|B_INVAL); 287 if (rbp->b_flags & (B_ASYNC|B_CALL)) 288 BUF_KERNPROC(rbp); 289 (void) VOP_STRATEGY(vp, rbp); 290 curproc->p_stats->p_ru.ru_inblock++; 291 } 292 } 293 if (reqbp) 294 return (biowait(reqbp)); 295 else 296 return (error); 297 } 298 299 /* 300 * If blocks are contiguous on disk, use this to provide clustered 301 * read ahead. We will read as many blocks as possible sequentially 302 * and then parcel them up into logical blocks in the buffer hash table. 303 */ 304 static struct buf * 305 cluster_rbuild(vp, filesize, lbn, blkno, size, run, fbp) 306 struct vnode *vp; 307 u_quad_t filesize; 308 daddr_t lbn; 309 daddr_t blkno; 310 long size; 311 int run; 312 struct buf *fbp; 313 { 314 struct buf *bp, *tbp; 315 daddr_t bn; 316 int i, inc, j; 317 318 KASSERT(size == vp->v_mount->mnt_stat.f_iosize, 319 ("cluster_rbuild: size %ld != filesize %ld\n", 320 size, vp->v_mount->mnt_stat.f_iosize)); 321 322 /* 323 * avoid a division 324 */ 325 while ((u_quad_t) size * (lbn + run) > filesize) { 326 --run; 327 } 328 329 if (fbp) { 330 tbp = fbp; 331 tbp->b_flags |= B_READ; 332 } else { 333 tbp = getblk(vp, lbn, size, 0, 0); 334 if (tbp->b_flags & B_CACHE) 335 return tbp; 336 tbp->b_flags |= B_ASYNC | B_READ | B_RAM; 337 } 338 339 tbp->b_blkno = blkno; 340 if( (tbp->b_flags & B_MALLOC) || 341 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1) ) 342 return tbp; 343 344 bp = trypbuf(&cluster_pbuf_freecnt); 345 if (bp == 0) 346 return tbp; 347 348 /* 349 * We are synthesizing a buffer out of vm_page_t's, but 350 * if the block size is not page aligned then the starting 351 * address may not be either. Inherit the b_data offset 352 * from the original buffer. 353 */ 354 bp->b_data = (char *)((vm_offset_t)bp->b_data | 355 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 356 bp->b_flags = B_ASYNC | B_READ | B_CALL | B_CLUSTER | B_VMIO; 357 bp->b_iodone = cluster_callback; 358 bp->b_blkno = blkno; 359 bp->b_lblkno = lbn; 360 bp->b_offset = tbp->b_offset; 361 KASSERT(bp->b_offset != NOOFFSET, ("cluster_rbuild: no buffer offset")); 362 pbgetvp(vp, bp); 363 364 TAILQ_INIT(&bp->b_cluster.cluster_head); 365 366 bp->b_bcount = 0; 367 bp->b_bufsize = 0; 368 bp->b_npages = 0; 369 370 inc = btodb(size); 371 for (bn = blkno, i = 0; i < run; ++i, bn += inc) { 372 if (i != 0) { 373 if ((bp->b_npages * PAGE_SIZE) + 374 round_page(size) > vp->v_mount->mnt_iosize_max) { 375 break; 376 } 377 378 /* 379 * Shortcut some checks and try to avoid buffers that 380 * would block in the lock. The same checks have to 381 * be made again after we officially get the buffer. 382 */ 383 if ((tbp = incore(vp, lbn + i)) != NULL) { 384 if (BUF_LOCK(tbp, LK_EXCLUSIVE | LK_NOWAIT)) 385 break; 386 BUF_UNLOCK(tbp); 387 388 for (j = 0; j < tbp->b_npages; j++) { 389 if (tbp->b_pages[j]->valid) 390 break; 391 } 392 393 if (j != tbp->b_npages) 394 break; 395 396 if (tbp->b_bcount != size) 397 break; 398 } 399 400 tbp = getblk(vp, lbn + i, size, 0, 0); 401 402 /* 403 * Stop scanning if the buffer is fuly valid 404 * (marked B_CACHE), or locked (may be doing a 405 * background write), or if the buffer is not 406 * VMIO backed. The clustering code can only deal 407 * with VMIO-backed buffers. 408 */ 409 if ((tbp->b_flags & (B_CACHE|B_LOCKED)) || 410 (tbp->b_flags & B_VMIO) == 0) { 411 bqrelse(tbp); 412 break; 413 } 414 415 /* 416 * The buffer must be completely invalid in order to 417 * take part in the cluster. If it is partially valid 418 * then we stop. 419 */ 420 for (j = 0;j < tbp->b_npages; j++) { 421 if (tbp->b_pages[j]->valid) 422 break; 423 } 424 if (j != tbp->b_npages) { 425 bqrelse(tbp); 426 break; 427 } 428 429 /* 430 * Set a read-ahead mark as appropriate 431 */ 432 if ((fbp && (i == 1)) || (i == (run - 1))) 433 tbp->b_flags |= B_RAM; 434 435 /* 436 * Set the buffer up for an async read (XXX should 437 * we do this only if we do not wind up brelse()ing?). 438 * Set the block number if it isn't set, otherwise 439 * if it is make sure it matches the block number we 440 * expect. 441 */ 442 tbp->b_flags |= B_READ | B_ASYNC; 443 if (tbp->b_blkno == tbp->b_lblkno) { 444 tbp->b_blkno = bn; 445 } else if (tbp->b_blkno != bn) { 446 brelse(tbp); 447 break; 448 } 449 } 450 /* 451 * XXX fbp from caller may not be B_ASYNC, but we are going 452 * to biodone() it in cluster_callback() anyway 453 */ 454 BUF_KERNPROC(tbp); 455 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head, 456 tbp, b_cluster.cluster_entry); 457 for (j = 0; j < tbp->b_npages; j += 1) { 458 vm_page_t m; 459 m = tbp->b_pages[j]; 460 vm_page_io_start(m); 461 vm_object_pip_add(m->object, 1); 462 if ((bp->b_npages == 0) || 463 (bp->b_pages[bp->b_npages-1] != m)) { 464 bp->b_pages[bp->b_npages] = m; 465 bp->b_npages++; 466 } 467 if ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) 468 tbp->b_pages[j] = bogus_page; 469 } 470 /* 471 * XXX shouldn't this be += size for both, like in 472 * cluster_wbuild()? 473 * 474 * Don't inherit tbp->b_bufsize as it may be larger due to 475 * a non-page-aligned size. Instead just aggregate using 476 * 'size'. 477 */ 478 if (tbp->b_bcount != size) 479 printf("warning: tbp->b_bcount wrong %ld vs %ld\n", tbp->b_bcount, size); 480 if (tbp->b_bufsize != size) 481 printf("warning: tbp->b_bufsize wrong %ld vs %ld\n", tbp->b_bufsize, size); 482 bp->b_bcount += size; 483 bp->b_bufsize += size; 484 } 485 486 /* 487 * Fully valid pages in the cluster are already good and do not need 488 * to be re-read from disk. Replace the page with bogus_page 489 */ 490 for (j = 0; j < bp->b_npages; j++) { 491 if ((bp->b_pages[j]->valid & VM_PAGE_BITS_ALL) == 492 VM_PAGE_BITS_ALL) { 493 bp->b_pages[j] = bogus_page; 494 } 495 } 496 if (bp->b_bufsize > bp->b_kvasize) 497 panic("cluster_rbuild: b_bufsize(%ld) > b_kvasize(%d)\n", 498 bp->b_bufsize, bp->b_kvasize); 499 bp->b_kvasize = bp->b_bufsize; 500 501 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 502 (vm_page_t *)bp->b_pages, bp->b_npages); 503 return (bp); 504 } 505 506 /* 507 * Cleanup after a clustered read or write. 508 * This is complicated by the fact that any of the buffers might have 509 * extra memory (if there were no empty buffer headers at allocbuf time) 510 * that we will need to shift around. 511 */ 512 void 513 cluster_callback(bp) 514 struct buf *bp; 515 { 516 struct buf *nbp, *tbp; 517 int error = 0; 518 519 /* 520 * Must propogate errors to all the components. 521 */ 522 if (bp->b_flags & B_ERROR) 523 error = bp->b_error; 524 525 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages); 526 /* 527 * Move memory from the large cluster buffer into the component 528 * buffers and mark IO as done on these. 529 */ 530 for (tbp = TAILQ_FIRST(&bp->b_cluster.cluster_head); 531 tbp; tbp = nbp) { 532 nbp = TAILQ_NEXT(&tbp->b_cluster, cluster_entry); 533 if (error) { 534 tbp->b_flags |= B_ERROR; 535 tbp->b_error = error; 536 } else { 537 tbp->b_dirtyoff = tbp->b_dirtyend = 0; 538 tbp->b_flags &= ~(B_ERROR|B_INVAL); 539 /* 540 * XXX the bdwrite()/bqrelse() issued during 541 * cluster building clears B_RELBUF (see bqrelse() 542 * comment). If direct I/O was specified, we have 543 * to restore it here to allow the buffer and VM 544 * to be freed. 545 */ 546 if (tbp->b_flags & B_DIRECT) 547 tbp->b_flags |= B_RELBUF; 548 } 549 biodone(tbp); 550 } 551 relpbuf(bp, &cluster_pbuf_freecnt); 552 } 553 554 /* 555 * cluster_wbuild_wb: 556 * 557 * Implement modified write build for cluster. 558 * 559 * write_behind = 0 write behind disabled 560 * write_behind = 1 write behind normal (default) 561 * write_behind = 2 write behind backed-off 562 */ 563 564 static __inline int 565 cluster_wbuild_wb(struct vnode *vp, long size, daddr_t start_lbn, int len) 566 { 567 int r = 0; 568 569 switch(write_behind) { 570 case 2: 571 if (start_lbn < len) 572 break; 573 start_lbn -= len; 574 /* fall through */ 575 case 1: 576 r = cluster_wbuild(vp, size, start_lbn, len); 577 /* fall through */ 578 default: 579 /* fall through */ 580 break; 581 } 582 return(r); 583 } 584 585 /* 586 * Do clustered write for FFS. 587 * 588 * Three cases: 589 * 1. Write is not sequential (write asynchronously) 590 * Write is sequential: 591 * 2. beginning of cluster - begin cluster 592 * 3. middle of a cluster - add to cluster 593 * 4. end of a cluster - asynchronously write cluster 594 */ 595 void 596 cluster_write(bp, filesize, seqcount) 597 struct buf *bp; 598 u_quad_t filesize; 599 int seqcount; 600 { 601 struct vnode *vp; 602 daddr_t lbn; 603 int maxclen, cursize; 604 int lblocksize; 605 int async; 606 607 vp = bp->b_vp; 608 if (vp->v_type == VREG) { 609 async = vp->v_mount->mnt_flag & MNT_ASYNC; 610 lblocksize = vp->v_mount->mnt_stat.f_iosize; 611 } else { 612 async = 0; 613 lblocksize = bp->b_bufsize; 614 } 615 lbn = bp->b_lblkno; 616 KASSERT(bp->b_offset != NOOFFSET, ("cluster_write: no buffer offset")); 617 618 /* Initialize vnode to beginning of file. */ 619 if (lbn == 0) 620 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0; 621 622 if (vp->v_clen == 0 || lbn != vp->v_lastw + 1 || 623 (bp->b_blkno != vp->v_lasta + btodb(lblocksize))) { 624 maxclen = vp->v_mount->mnt_iosize_max / lblocksize - 1; 625 if (vp->v_clen != 0) { 626 /* 627 * Next block is not sequential. 628 * 629 * If we are not writing at end of file, the process 630 * seeked to another point in the file since its last 631 * write, or we have reached our maximum cluster size, 632 * then push the previous cluster. Otherwise try 633 * reallocating to make it sequential. 634 * 635 * Change to algorithm: only push previous cluster if 636 * it was sequential from the point of view of the 637 * seqcount heuristic, otherwise leave the buffer 638 * intact so we can potentially optimize the I/O 639 * later on in the buf_daemon or update daemon 640 * flush. 641 */ 642 cursize = vp->v_lastw - vp->v_cstart + 1; 643 if (((u_quad_t) bp->b_offset + lblocksize) != filesize || 644 lbn != vp->v_lastw + 1 || vp->v_clen <= cursize) { 645 if (!async && seqcount > 0) { 646 cluster_wbuild_wb(vp, lblocksize, 647 vp->v_cstart, cursize); 648 } 649 } else { 650 struct buf **bpp, **endbp; 651 struct cluster_save *buflist; 652 653 buflist = cluster_collectbufs(vp, bp); 654 endbp = &buflist->bs_children 655 [buflist->bs_nchildren - 1]; 656 if (VOP_REALLOCBLKS(vp, buflist)) { 657 /* 658 * Failed, push the previous cluster 659 * if *really* writing sequentially 660 * in the logical file (seqcount > 1), 661 * otherwise delay it in the hopes that 662 * the low level disk driver can 663 * optimize the write ordering. 664 */ 665 for (bpp = buflist->bs_children; 666 bpp < endbp; bpp++) 667 brelse(*bpp); 668 free(buflist, M_SEGMENT); 669 if (seqcount > 1) { 670 cluster_wbuild_wb(vp, 671 lblocksize, vp->v_cstart, 672 cursize); 673 } 674 } else { 675 /* 676 * Succeeded, keep building cluster. 677 */ 678 for (bpp = buflist->bs_children; 679 bpp <= endbp; bpp++) 680 bdwrite(*bpp); 681 free(buflist, M_SEGMENT); 682 vp->v_lastw = lbn; 683 vp->v_lasta = bp->b_blkno; 684 return; 685 } 686 } 687 } 688 /* 689 * Consider beginning a cluster. If at end of file, make 690 * cluster as large as possible, otherwise find size of 691 * existing cluster. 692 */ 693 if ((vp->v_type == VREG) && 694 ((u_quad_t) bp->b_offset + lblocksize) != filesize && 695 (bp->b_blkno == bp->b_lblkno) && 696 (VOP_BMAP(vp, lbn, NULL, &bp->b_blkno, &maxclen, NULL) || 697 bp->b_blkno == -1)) { 698 bawrite(bp); 699 vp->v_clen = 0; 700 vp->v_lasta = bp->b_blkno; 701 vp->v_cstart = lbn + 1; 702 vp->v_lastw = lbn; 703 return; 704 } 705 vp->v_clen = maxclen; 706 if (!async && maxclen == 0) { /* I/O not contiguous */ 707 vp->v_cstart = lbn + 1; 708 bawrite(bp); 709 } else { /* Wait for rest of cluster */ 710 vp->v_cstart = lbn; 711 bdwrite(bp); 712 } 713 } else if (lbn == vp->v_cstart + vp->v_clen) { 714 /* 715 * At end of cluster, write it out if seqcount tells us we 716 * are operating sequentially, otherwise let the buf or 717 * update daemon handle it. 718 */ 719 bdwrite(bp); 720 if (seqcount > 1) 721 cluster_wbuild_wb(vp, lblocksize, vp->v_cstart, vp->v_clen + 1); 722 vp->v_clen = 0; 723 vp->v_cstart = lbn + 1; 724 } else if (vm_page_count_severe()) { 725 /* 726 * We are low on memory, get it going NOW 727 */ 728 bawrite(bp); 729 } else { 730 /* 731 * In the middle of a cluster, so just delay the I/O for now. 732 */ 733 bdwrite(bp); 734 } 735 vp->v_lastw = lbn; 736 vp->v_lasta = bp->b_blkno; 737 } 738 739 740 /* 741 * This is an awful lot like cluster_rbuild...wish they could be combined. 742 * The last lbn argument is the current block on which I/O is being 743 * performed. Check to see that it doesn't fall in the middle of 744 * the current block (if last_bp == NULL). 745 */ 746 int 747 cluster_wbuild(vp, size, start_lbn, len) 748 struct vnode *vp; 749 long size; 750 daddr_t start_lbn; 751 int len; 752 { 753 struct buf *bp, *tbp; 754 int i, j, s; 755 int totalwritten = 0; 756 int dbsize = btodb(size); 757 758 while (len > 0) { 759 s = splbio(); 760 /* 761 * If the buffer is not delayed-write (i.e. dirty), or it 762 * is delayed-write but either locked or inval, it cannot 763 * partake in the clustered write. 764 */ 765 if (((tbp = gbincore(vp, start_lbn)) == NULL) || 766 ((tbp->b_flags & (B_LOCKED | B_INVAL | B_DELWRI)) != B_DELWRI) || 767 BUF_LOCK(tbp, LK_EXCLUSIVE | LK_NOWAIT)) { 768 ++start_lbn; 769 --len; 770 splx(s); 771 continue; 772 } 773 bremfree(tbp); 774 tbp->b_flags &= ~B_DONE; 775 splx(s); 776 777 /* 778 * Extra memory in the buffer, punt on this buffer. 779 * XXX we could handle this in most cases, but we would 780 * have to push the extra memory down to after our max 781 * possible cluster size and then potentially pull it back 782 * up if the cluster was terminated prematurely--too much 783 * hassle. 784 */ 785 if (((tbp->b_flags & (B_CLUSTEROK|B_MALLOC)) != B_CLUSTEROK) || 786 (tbp->b_bcount != tbp->b_bufsize) || 787 (tbp->b_bcount != size) || 788 (len == 1) || 789 ((bp = getpbuf(&cluster_pbuf_freecnt)) == NULL)) { 790 totalwritten += tbp->b_bufsize; 791 bawrite(tbp); 792 ++start_lbn; 793 --len; 794 continue; 795 } 796 797 /* 798 * We got a pbuf to make the cluster in. 799 * so initialise it. 800 */ 801 TAILQ_INIT(&bp->b_cluster.cluster_head); 802 bp->b_bcount = 0; 803 bp->b_bufsize = 0; 804 bp->b_npages = 0; 805 if (tbp->b_wcred != NOCRED) { 806 bp->b_wcred = tbp->b_wcred; 807 crhold(bp->b_wcred); 808 } 809 810 bp->b_blkno = tbp->b_blkno; 811 bp->b_lblkno = tbp->b_lblkno; 812 bp->b_offset = tbp->b_offset; 813 814 /* 815 * We are synthesizing a buffer out of vm_page_t's, but 816 * if the block size is not page aligned then the starting 817 * address may not be either. Inherit the b_data offset 818 * from the original buffer. 819 */ 820 bp->b_data = (char *)((vm_offset_t)bp->b_data | 821 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 822 bp->b_flags |= B_CALL | B_CLUSTER | 823 (tbp->b_flags & (B_VMIO | B_NEEDCOMMIT | B_NOWDRAIN)); 824 bp->b_iodone = cluster_callback; 825 pbgetvp(vp, bp); 826 /* 827 * From this location in the file, scan forward to see 828 * if there are buffers with adjacent data that need to 829 * be written as well. 830 */ 831 for (i = 0; i < len; ++i, ++start_lbn) { 832 if (i != 0) { /* If not the first buffer */ 833 s = splbio(); 834 /* 835 * If the adjacent data is not even in core it 836 * can't need to be written. 837 */ 838 if ((tbp = gbincore(vp, start_lbn)) == NULL) { 839 splx(s); 840 break; 841 } 842 843 /* 844 * If it IS in core, but has different 845 * characteristics, or is locked (which 846 * means it could be undergoing a background 847 * I/O or be in a weird state), then don't 848 * cluster with it. 849 */ 850 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK | 851 B_INVAL | B_DELWRI | B_NEEDCOMMIT)) 852 != (B_DELWRI | B_CLUSTEROK | 853 (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) || 854 (tbp->b_flags & B_LOCKED) || 855 tbp->b_wcred != bp->b_wcred || 856 BUF_LOCK(tbp, LK_EXCLUSIVE | LK_NOWAIT)) { 857 splx(s); 858 break; 859 } 860 861 /* 862 * Check that the combined cluster 863 * would make sense with regard to pages 864 * and would not be too large 865 */ 866 if ((tbp->b_bcount != size) || 867 ((bp->b_blkno + (dbsize * i)) != 868 tbp->b_blkno) || 869 ((tbp->b_npages + bp->b_npages) > 870 (vp->v_mount->mnt_iosize_max / PAGE_SIZE))) { 871 BUF_UNLOCK(tbp); 872 splx(s); 873 break; 874 } 875 /* 876 * Ok, it's passed all the tests, 877 * so remove it from the free list 878 * and mark it busy. We will use it. 879 */ 880 bremfree(tbp); 881 tbp->b_flags &= ~B_DONE; 882 splx(s); 883 } /* end of code for non-first buffers only */ 884 /* check for latent dependencies to be handled */ 885 if ((LIST_FIRST(&tbp->b_dep)) != NULL && 886 bioops.io_start) 887 (*bioops.io_start)(tbp); 888 /* 889 * If the IO is via the VM then we do some 890 * special VM hackery (yuck). Since the buffer's 891 * block size may not be page-aligned it is possible 892 * for a page to be shared between two buffers. We 893 * have to get rid of the duplication when building 894 * the cluster. 895 */ 896 if (tbp->b_flags & B_VMIO) { 897 vm_page_t m; 898 899 if (i != 0) { /* if not first buffer */ 900 for (j = 0; j < tbp->b_npages; j += 1) { 901 m = tbp->b_pages[j]; 902 if (m->flags & PG_BUSY) { 903 bqrelse(tbp); 904 goto finishcluster; 905 } 906 } 907 } 908 909 for (j = 0; j < tbp->b_npages; j += 1) { 910 m = tbp->b_pages[j]; 911 vm_page_io_start(m); 912 vm_object_pip_add(m->object, 1); 913 if ((bp->b_npages == 0) || 914 (bp->b_pages[bp->b_npages - 1] != m)) { 915 bp->b_pages[bp->b_npages] = m; 916 bp->b_npages++; 917 } 918 } 919 } 920 bp->b_bcount += size; 921 bp->b_bufsize += size; 922 923 s = splbio(); 924 bundirty(tbp); 925 tbp->b_flags &= ~(B_READ | B_DONE | B_ERROR); 926 tbp->b_flags |= B_ASYNC; 927 reassignbuf(tbp, tbp->b_vp); /* put on clean list */ 928 ++tbp->b_vp->v_numoutput; 929 splx(s); 930 BUF_KERNPROC(tbp); 931 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head, 932 tbp, b_cluster.cluster_entry); 933 } 934 finishcluster: 935 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 936 (vm_page_t *) bp->b_pages, bp->b_npages); 937 if (bp->b_bufsize > bp->b_kvasize) 938 panic( 939 "cluster_wbuild: b_bufsize(%ld) > b_kvasize(%d)\n", 940 bp->b_bufsize, bp->b_kvasize); 941 bp->b_kvasize = bp->b_bufsize; 942 totalwritten += bp->b_bufsize; 943 bp->b_dirtyoff = 0; 944 bp->b_dirtyend = bp->b_bufsize; 945 bawrite(bp); 946 947 len -= i; 948 } 949 return totalwritten; 950 } 951 952 /* 953 * Collect together all the buffers in a cluster. 954 * Plus add one additional buffer. 955 */ 956 static struct cluster_save * 957 cluster_collectbufs(vp, last_bp) 958 struct vnode *vp; 959 struct buf *last_bp; 960 { 961 struct cluster_save *buflist; 962 struct buf *bp; 963 daddr_t lbn; 964 int i, len; 965 966 len = vp->v_lastw - vp->v_cstart + 1; 967 buflist = malloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist), 968 M_SEGMENT, M_WAITOK); 969 buflist->bs_nchildren = 0; 970 buflist->bs_children = (struct buf **) (buflist + 1); 971 for (lbn = vp->v_cstart, i = 0; i < len; lbn++, i++) { 972 (void) bread(vp, lbn, last_bp->b_bcount, NOCRED, &bp); 973 buflist->bs_children[i] = bp; 974 if (bp->b_blkno == bp->b_lblkno) 975 VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno, 976 NULL, NULL); 977 } 978 buflist->bs_children[i] = bp = last_bp; 979 if (bp->b_blkno == bp->b_lblkno) 980 VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno, 981 NULL, NULL); 982 buflist->bs_nchildren = i + 1; 983 return (buflist); 984 }
Cache object: ecbfb12c3e06d10e7740ba1cbc3467e7
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