Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]
FreeBSD/Linux Kernel Cross Reference
sys/kern/vfs_cluster.c
Version:
- FREEBSD - FREEBSD-13-STABLE - FREEBSD-13-0 - FREEBSD-12-STABLE - FREEBSD-12-0 - FREEBSD-11-STABLE - FREEBSD-11-0 - FREEBSD-10-STABLE - FREEBSD-10-0 - FREEBSD-9-STABLE - FREEBSD-9-0 - FREEBSD-8-STABLE - FREEBSD-8-0 - FREEBSD-7-STABLE - FREEBSD-7-0 - FREEBSD-6-STABLE - FREEBSD-6-0 - FREEBSD-5-STABLE - FREEBSD-5-0 - FREEBSD-4-STABLE - FREEBSD-3-STABLE - FREEBSD22 - l41 - OPENBSD - linux-2.6 - MK84 - PLAN9 - xnu-8792
SearchContext: - none - 3 - 10
SearchContext: - none - 3 - 10
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 * 4. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 * 31 * @(#)vfs_cluster.c 8.7 (Berkeley) 2/13/94 32 */ 33 34 #include <sys/cdefs.h> 35 __FBSDID("$FreeBSD: src/sys/kern/vfs_cluster.c,v 1.150.2.2 2005/08/16 15:09:44 sobomax Exp $"); 36 37 #include "opt_debug_cluster.h" 38 39 #include <sys/param.h> 40 #include <sys/systm.h> 41 #include <sys/kernel.h> 42 #include <sys/proc.h> 43 #include <sys/bio.h> 44 #include <sys/buf.h> 45 #include <sys/vnode.h> 46 #include <sys/malloc.h> 47 #include <sys/mount.h> 48 #include <sys/resourcevar.h> 49 #include <sys/vmmeter.h> 50 #include <vm/vm.h> 51 #include <vm/vm_object.h> 52 #include <vm/vm_page.h> 53 #include <sys/sysctl.h> 54 55 #if defined(CLUSTERDEBUG) 56 static int rcluster= 0; 57 SYSCTL_INT(_debug, OID_AUTO, rcluster, CTLFLAG_RW, &rcluster, 0, 58 "Debug VFS clustering code"); 59 #endif 60 61 static MALLOC_DEFINE(M_SEGMENT, "cluster_save buffer", "cluster_save buffer"); 62 63 static struct cluster_save * 64 cluster_collectbufs(struct vnode *vp, struct buf *last_bp); 65 static struct buf * 66 cluster_rbuild(struct vnode *vp, u_quad_t filesize, daddr_t lbn, 67 daddr_t blkno, long size, int run, struct buf *fbp); 68 69 static int write_behind = 1; 70 SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0, 71 "Cluster write-behind; 0: disable, 1: enable, 2: backed off"); 72 73 static int read_max = 8; 74 SYSCTL_INT(_vfs, OID_AUTO, read_max, CTLFLAG_RW, &read_max, 0, 75 "Cluster read-ahead max block count"); 76 77 /* Page expended to mark partially backed buffers */ 78 extern vm_page_t bogus_page; 79 80 /* 81 * Read data to a buf, including read-ahead if we find this to be beneficial. 82 * cluster_read replaces bread. 83 */ 84 int 85 cluster_read(vp, filesize, lblkno, size, cred, totread, seqcount, bpp) 86 struct vnode *vp; 87 u_quad_t filesize; 88 daddr_t lblkno; 89 long size; 90 struct ucred *cred; 91 long totread; 92 int seqcount; 93 struct buf **bpp; 94 { 95 struct buf *bp, *rbp, *reqbp; 96 daddr_t blkno, origblkno; 97 int maxra, racluster; 98 int error, ncontig; 99 int i; 100 101 error = 0; 102 103 /* 104 * Try to limit the amount of read-ahead by a few 105 * ad-hoc parameters. This needs work!!! 106 */ 107 racluster = vp->v_mount->mnt_iosize_max / size; 108 maxra = seqcount; 109 maxra = min(read_max, maxra); 110 maxra = min(nbuf/8, maxra); 111 if (((u_quad_t)(lblkno + maxra + 1) * size) > filesize) 112 maxra = (filesize / size) - lblkno; 113 114 /* 115 * get the requested block 116 */ 117 *bpp = reqbp = bp = getblk(vp, lblkno, size, 0, 0, 0); 118 origblkno = lblkno; 119 120 /* 121 * if it is in the cache, then check to see if the reads have been 122 * sequential. If they have, then try some read-ahead, otherwise 123 * back-off on prospective read-aheads. 124 */ 125 if (bp->b_flags & B_CACHE) { 126 if (!seqcount) { 127 return 0; 128 } else if ((bp->b_flags & B_RAM) == 0) { 129 return 0; 130 } else { 131 int s; 132 bp->b_flags &= ~B_RAM; 133 /* 134 * We do the spl here so that there is no window 135 * between the incore and the b_usecount increment 136 * below. We opt to keep the spl out of the loop 137 * for efficiency. 138 */ 139 s = splbio(); 140 VI_LOCK(vp); 141 for (i = 1; i < maxra; i++) { 142 /* 143 * Stop if the buffer does not exist or it 144 * is invalid (about to go away?) 145 */ 146 rbp = gbincore(vp, lblkno+i); 147 if (rbp == NULL || (rbp->b_flags & B_INVAL)) 148 break; 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 rbp->b_flags |= B_RAM; 157 } 158 VI_UNLOCK(vp); 159 splx(s); 160 if (i >= maxra) { 161 return 0; 162 } 163 lblkno += i; 164 } 165 reqbp = bp = NULL; 166 /* 167 * If it isn't in the cache, then get a chunk from 168 * disk if sequential, otherwise just get the block. 169 */ 170 } else { 171 off_t firstread = bp->b_offset; 172 int nblks; 173 174 KASSERT(bp->b_offset != NOOFFSET, 175 ("cluster_read: no buffer offset")); 176 177 ncontig = 0; 178 179 /* 180 * Compute the total number of blocks that we should read 181 * synchronously. 182 */ 183 if (firstread + totread > filesize) 184 totread = filesize - firstread; 185 nblks = howmany(totread, size); 186 if (nblks > racluster) 187 nblks = racluster; 188 189 /* 190 * Now compute the number of contiguous blocks. 191 */ 192 if (nblks > 1) { 193 error = VOP_BMAP(vp, lblkno, NULL, 194 &blkno, &ncontig, NULL); 195 /* 196 * If this failed to map just do the original block. 197 */ 198 if (error || blkno == -1) 199 ncontig = 0; 200 } 201 202 /* 203 * If we have contiguous data available do a cluster 204 * otherwise just read the requested block. 205 */ 206 if (ncontig) { 207 /* Account for our first block. */ 208 ncontig = min(ncontig + 1, nblks); 209 if (ncontig < nblks) 210 nblks = ncontig; 211 bp = cluster_rbuild(vp, filesize, lblkno, 212 blkno, size, nblks, bp); 213 lblkno += (bp->b_bufsize / size); 214 } else { 215 bp->b_flags |= B_RAM; 216 bp->b_iocmd = BIO_READ; 217 lblkno += 1; 218 } 219 } 220 221 /* 222 * handle the synchronous read so that it is available ASAP. 223 */ 224 if (bp) { 225 if ((bp->b_flags & B_CLUSTER) == 0) { 226 vfs_busy_pages(bp, 0); 227 } 228 bp->b_flags &= ~B_INVAL; 229 bp->b_ioflags &= ~BIO_ERROR; 230 if ((bp->b_flags & B_ASYNC) || bp->b_iodone != NULL) 231 BUF_KERNPROC(bp); 232 bp->b_iooffset = dbtob(bp->b_blkno); 233 error = VOP_STRATEGY(vp, bp); 234 curproc->p_stats->p_ru.ru_inblock++; 235 if (error) 236 return (error); 237 } 238 239 /* 240 * If we have been doing sequential I/O, then do some read-ahead. 241 */ 242 while (lblkno < (origblkno + maxra)) { 243 error = VOP_BMAP(vp, lblkno, NULL, &blkno, &ncontig, NULL); 244 if (error) 245 break; 246 247 if (blkno == -1) 248 break; 249 250 /* 251 * We could throttle ncontig here by maxra but we might as 252 * well read the data if it is contiguous. We're throttled 253 * by racluster anyway. 254 */ 255 if (ncontig) { 256 ncontig = min(ncontig + 1, racluster); 257 rbp = cluster_rbuild(vp, filesize, lblkno, blkno, 258 size, ncontig, NULL); 259 lblkno += (rbp->b_bufsize / size); 260 if (rbp->b_flags & B_DELWRI) { 261 bqrelse(rbp); 262 continue; 263 } 264 } else { 265 rbp = getblk(vp, lblkno, size, 0, 0, 0); 266 lblkno += 1; 267 if (rbp->b_flags & B_DELWRI) { 268 bqrelse(rbp); 269 continue; 270 } 271 rbp->b_flags |= B_ASYNC | B_RAM; 272 rbp->b_iocmd = BIO_READ; 273 rbp->b_blkno = blkno; 274 } 275 if (rbp->b_flags & B_CACHE) { 276 rbp->b_flags &= ~B_ASYNC; 277 bqrelse(rbp); 278 continue; 279 } 280 if ((rbp->b_flags & B_CLUSTER) == 0) { 281 vfs_busy_pages(rbp, 0); 282 } 283 rbp->b_flags &= ~B_INVAL; 284 rbp->b_ioflags &= ~BIO_ERROR; 285 if ((rbp->b_flags & B_ASYNC) || rbp->b_iodone != NULL) 286 BUF_KERNPROC(rbp); 287 rbp->b_iooffset = dbtob(rbp->b_blkno); 288 (void) VOP_STRATEGY(vp, rbp); 289 curproc->p_stats->p_ru.ru_inblock++; 290 } 291 292 if (reqbp) 293 return (bufwait(reqbp)); 294 else 295 return (error); 296 } 297 298 /* 299 * If blocks are contiguous on disk, use this to provide clustered 300 * read ahead. We will read as many blocks as possible sequentially 301 * and then parcel them up into logical blocks in the buffer hash table. 302 */ 303 static struct buf * 304 cluster_rbuild(vp, filesize, lbn, blkno, size, run, fbp) 305 struct vnode *vp; 306 u_quad_t filesize; 307 daddr_t lbn; 308 daddr_t blkno; 309 long size; 310 int run; 311 struct buf *fbp; 312 { 313 struct buf *bp, *tbp; 314 daddr_t bn; 315 int i, inc, j; 316 317 GIANT_REQUIRED; 318 319 KASSERT(size == vp->v_mount->mnt_stat.f_iosize, 320 ("cluster_rbuild: size %ld != filesize %jd\n", 321 size, (intmax_t)vp->v_mount->mnt_stat.f_iosize)); 322 323 /* 324 * avoid a division 325 */ 326 while ((u_quad_t) size * (lbn + run) > filesize) { 327 --run; 328 } 329 330 if (fbp) { 331 tbp = fbp; 332 tbp->b_iocmd = BIO_READ; 333 } else { 334 tbp = getblk(vp, lbn, size, 0, 0, 0); 335 if (tbp->b_flags & B_CACHE) 336 return tbp; 337 tbp->b_flags |= B_ASYNC | B_RAM; 338 tbp->b_iocmd = BIO_READ; 339 } 340 341 tbp->b_blkno = blkno; 342 if( (tbp->b_flags & B_MALLOC) || 343 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1) ) 344 return tbp; 345 346 bp = trypbuf(&cluster_pbuf_freecnt); 347 if (bp == 0) 348 return tbp; 349 350 /* 351 * We are synthesizing a buffer out of vm_page_t's, but 352 * if the block size is not page aligned then the starting 353 * address may not be either. Inherit the b_data offset 354 * from the original buffer. 355 */ 356 bp->b_data = (char *)((vm_offset_t)bp->b_data | 357 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 358 bp->b_flags = B_ASYNC | B_CLUSTER | B_VMIO; 359 bp->b_iocmd = BIO_READ; 360 bp->b_iodone = cluster_callback; 361 bp->b_blkno = blkno; 362 bp->b_lblkno = lbn; 363 bp->b_offset = tbp->b_offset; 364 KASSERT(bp->b_offset != NOOFFSET, ("cluster_rbuild: no buffer offset")); 365 pbgetvp(vp, bp); 366 367 TAILQ_INIT(&bp->b_cluster.cluster_head); 368 369 bp->b_bcount = 0; 370 bp->b_bufsize = 0; 371 bp->b_npages = 0; 372 373 inc = btodb(size); 374 for (bn = blkno, i = 0; i < run; ++i, bn += inc) { 375 if (i != 0) { 376 if ((bp->b_npages * PAGE_SIZE) + 377 round_page(size) > vp->v_mount->mnt_iosize_max) { 378 break; 379 } 380 381 tbp = getblk(vp, lbn + i, size, 0, 0, GB_LOCK_NOWAIT); 382 383 /* Don't wait around for locked bufs. */ 384 if (tbp == NULL) 385 break; 386 387 /* 388 * Stop scanning if the buffer is fully valid 389 * (marked B_CACHE), or locked (may be doing a 390 * background write), or if the buffer is not 391 * VMIO backed. The clustering code can only deal 392 * with VMIO-backed buffers. 393 */ 394 VI_LOCK(bp->b_vp); 395 if ((tbp->b_vflags & BV_BKGRDINPROG) || 396 (tbp->b_flags & B_CACHE) || 397 (tbp->b_flags & B_VMIO) == 0) { 398 VI_UNLOCK(bp->b_vp); 399 bqrelse(tbp); 400 break; 401 } 402 VI_UNLOCK(bp->b_vp); 403 404 /* 405 * The buffer must be completely invalid in order to 406 * take part in the cluster. If it is partially valid 407 * then we stop. 408 */ 409 VM_OBJECT_LOCK(tbp->b_object); 410 for (j = 0;j < tbp->b_npages; j++) { 411 VM_OBJECT_LOCK_ASSERT(tbp->b_pages[j]->object, 412 MA_OWNED); 413 if (tbp->b_pages[j]->valid) 414 break; 415 } 416 VM_OBJECT_UNLOCK(tbp->b_object); 417 if (j != tbp->b_npages) { 418 bqrelse(tbp); 419 break; 420 } 421 422 /* 423 * Set a read-ahead mark as appropriate 424 */ 425 if ((fbp && (i == 1)) || (i == (run - 1))) 426 tbp->b_flags |= B_RAM; 427 428 /* 429 * Set the buffer up for an async read (XXX should 430 * we do this only if we do not wind up brelse()ing?). 431 * Set the block number if it isn't set, otherwise 432 * if it is make sure it matches the block number we 433 * expect. 434 */ 435 tbp->b_flags |= B_ASYNC; 436 tbp->b_iocmd = BIO_READ; 437 if (tbp->b_blkno == tbp->b_lblkno) { 438 tbp->b_blkno = bn; 439 } else if (tbp->b_blkno != bn) { 440 brelse(tbp); 441 break; 442 } 443 } 444 /* 445 * XXX fbp from caller may not be B_ASYNC, but we are going 446 * to biodone() it in cluster_callback() anyway 447 */ 448 BUF_KERNPROC(tbp); 449 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head, 450 tbp, b_cluster.cluster_entry); 451 VM_OBJECT_LOCK(tbp->b_object); 452 for (j = 0; j < tbp->b_npages; j += 1) { 453 vm_page_t m; 454 m = tbp->b_pages[j]; 455 vm_page_io_start(m); 456 vm_object_pip_add(m->object, 1); 457 if ((bp->b_npages == 0) || 458 (bp->b_pages[bp->b_npages-1] != m)) { 459 bp->b_pages[bp->b_npages] = m; 460 bp->b_npages++; 461 } 462 if ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) 463 tbp->b_pages[j] = bogus_page; 464 } 465 VM_OBJECT_UNLOCK(tbp->b_object); 466 /* 467 * XXX shouldn't this be += size for both, like in 468 * cluster_wbuild()? 469 * 470 * Don't inherit tbp->b_bufsize as it may be larger due to 471 * a non-page-aligned size. Instead just aggregate using 472 * 'size'. 473 */ 474 if (tbp->b_bcount != size) 475 printf("warning: tbp->b_bcount wrong %ld vs %ld\n", tbp->b_bcount, size); 476 if (tbp->b_bufsize != size) 477 printf("warning: tbp->b_bufsize wrong %ld vs %ld\n", tbp->b_bufsize, size); 478 bp->b_bcount += size; 479 bp->b_bufsize += size; 480 } 481 482 /* 483 * Fully valid pages in the cluster are already good and do not need 484 * to be re-read from disk. Replace the page with bogus_page 485 */ 486 VM_OBJECT_LOCK(bp->b_object); 487 for (j = 0; j < bp->b_npages; j++) { 488 VM_OBJECT_LOCK_ASSERT(bp->b_pages[j]->object, MA_OWNED); 489 if ((bp->b_pages[j]->valid & VM_PAGE_BITS_ALL) == 490 VM_PAGE_BITS_ALL) { 491 bp->b_pages[j] = bogus_page; 492 } 493 } 494 VM_OBJECT_UNLOCK(bp->b_object); 495 if (bp->b_bufsize > bp->b_kvasize) 496 panic("cluster_rbuild: b_bufsize(%ld) > b_kvasize(%d)\n", 497 bp->b_bufsize, bp->b_kvasize); 498 bp->b_kvasize = bp->b_bufsize; 499 500 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 501 (vm_page_t *)bp->b_pages, bp->b_npages); 502 return (bp); 503 } 504 505 /* 506 * Cleanup after a clustered read or write. 507 * This is complicated by the fact that any of the buffers might have 508 * extra memory (if there were no empty buffer headers at allocbuf time) 509 * that we will need to shift around. 510 */ 511 void 512 cluster_callback(bp) 513 struct buf *bp; 514 { 515 struct buf *nbp, *tbp; 516 int error = 0; 517 518 GIANT_REQUIRED; 519 520 /* 521 * Must propogate errors to all the components. 522 */ 523 if (bp->b_ioflags & BIO_ERROR) 524 error = bp->b_error; 525 526 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages); 527 /* 528 * Move memory from the large cluster buffer into the component 529 * buffers and mark IO as done on these. 530 */ 531 for (tbp = TAILQ_FIRST(&bp->b_cluster.cluster_head); 532 tbp; tbp = nbp) { 533 nbp = TAILQ_NEXT(&tbp->b_cluster, cluster_entry); 534 if (error) { 535 tbp->b_ioflags |= BIO_ERROR; 536 tbp->b_error = error; 537 } else { 538 tbp->b_dirtyoff = tbp->b_dirtyend = 0; 539 tbp->b_flags &= ~B_INVAL; 540 tbp->b_ioflags &= ~BIO_ERROR; 541 /* 542 * XXX the bdwrite()/bqrelse() issued during 543 * cluster building clears B_RELBUF (see bqrelse() 544 * comment). If direct I/O was specified, we have 545 * to restore it here to allow the buffer and VM 546 * to be freed. 547 */ 548 if (tbp->b_flags & B_DIRECT) 549 tbp->b_flags |= B_RELBUF; 550 } 551 bufdone(tbp); 552 } 553 relpbuf(bp, &cluster_pbuf_freecnt); 554 } 555 556 /* 557 * cluster_wbuild_wb: 558 * 559 * Implement modified write build for cluster. 560 * 561 * write_behind = 0 write behind disabled 562 * write_behind = 1 write behind normal (default) 563 * write_behind = 2 write behind backed-off 564 */ 565 566 static __inline int 567 cluster_wbuild_wb(struct vnode *vp, long size, daddr_t start_lbn, int len) 568 { 569 int r = 0; 570 571 switch(write_behind) { 572 case 2: 573 if (start_lbn < len) 574 break; 575 start_lbn -= len; 576 /* FALLTHROUGH */ 577 case 1: 578 r = cluster_wbuild(vp, size, start_lbn, len); 579 /* FALLTHROUGH */ 580 default: 581 /* FALLTHROUGH */ 582 break; 583 } 584 return(r); 585 } 586 587 /* 588 * Do clustered write for FFS. 589 * 590 * Three cases: 591 * 1. Write is not sequential (write asynchronously) 592 * Write is sequential: 593 * 2. beginning of cluster - begin cluster 594 * 3. middle of a cluster - add to cluster 595 * 4. end of a cluster - asynchronously write cluster 596 */ 597 void 598 cluster_write(bp, filesize, seqcount) 599 struct buf *bp; 600 u_quad_t filesize; 601 int seqcount; 602 { 603 struct vnode *vp; 604 daddr_t lbn; 605 int maxclen, cursize; 606 int lblocksize; 607 int async; 608 609 vp = bp->b_vp; 610 if (vp->v_type == VREG) { 611 async = vp->v_mount->mnt_flag & MNT_ASYNC; 612 lblocksize = vp->v_mount->mnt_stat.f_iosize; 613 } else { 614 async = 0; 615 lblocksize = bp->b_bufsize; 616 } 617 lbn = bp->b_lblkno; 618 KASSERT(bp->b_offset != NOOFFSET, ("cluster_write: no buffer offset")); 619 620 /* Initialize vnode to beginning of file. */ 621 if (lbn == 0) 622 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0; 623 624 if (vp->v_clen == 0 || lbn != vp->v_lastw + 1 || 625 (bp->b_blkno != vp->v_lasta + btodb(lblocksize))) { 626 maxclen = vp->v_mount->mnt_iosize_max / lblocksize - 1; 627 if (vp->v_clen != 0) { 628 /* 629 * Next block is not sequential. 630 * 631 * If we are not writing at end of file, the process 632 * seeked to another point in the file since its last 633 * write, or we have reached our maximum cluster size, 634 * then push the previous cluster. Otherwise try 635 * reallocating to make it sequential. 636 * 637 * Change to algorithm: only push previous cluster if 638 * it was sequential from the point of view of the 639 * seqcount heuristic, otherwise leave the buffer 640 * intact so we can potentially optimize the I/O 641 * later on in the buf_daemon or update daemon 642 * flush. 643 */ 644 cursize = vp->v_lastw - vp->v_cstart + 1; 645 if (((u_quad_t) bp->b_offset + lblocksize) != filesize || 646 lbn != vp->v_lastw + 1 || vp->v_clen <= cursize) { 647 if (!async && seqcount > 0) { 648 cluster_wbuild_wb(vp, lblocksize, 649 vp->v_cstart, cursize); 650 } 651 } else { 652 struct buf **bpp, **endbp; 653 struct cluster_save *buflist; 654 655 buflist = cluster_collectbufs(vp, bp); 656 endbp = &buflist->bs_children 657 [buflist->bs_nchildren - 1]; 658 if (VOP_REALLOCBLKS(vp, buflist)) { 659 /* 660 * Failed, push the previous cluster 661 * if *really* writing sequentially 662 * in the logical file (seqcount > 1), 663 * otherwise delay it in the hopes that 664 * the low level disk driver can 665 * optimize the write ordering. 666 */ 667 for (bpp = buflist->bs_children; 668 bpp < endbp; bpp++) 669 brelse(*bpp); 670 free(buflist, M_SEGMENT); 671 if (seqcount > 1) { 672 cluster_wbuild_wb(vp, 673 lblocksize, vp->v_cstart, 674 cursize); 675 } 676 } else { 677 /* 678 * Succeeded, keep building cluster. 679 */ 680 for (bpp = buflist->bs_children; 681 bpp <= endbp; bpp++) 682 bdwrite(*bpp); 683 free(buflist, M_SEGMENT); 684 vp->v_lastw = lbn; 685 vp->v_lasta = bp->b_blkno; 686 return; 687 } 688 } 689 } 690 /* 691 * Consider beginning a cluster. If at end of file, make 692 * cluster as large as possible, otherwise find size of 693 * existing cluster. 694 */ 695 if ((vp->v_type == VREG) && 696 ((u_quad_t) bp->b_offset + lblocksize) != filesize && 697 (bp->b_blkno == bp->b_lblkno) && 698 (VOP_BMAP(vp, lbn, NULL, &bp->b_blkno, &maxclen, NULL) || 699 bp->b_blkno == -1)) { 700 bawrite(bp); 701 vp->v_clen = 0; 702 vp->v_lasta = bp->b_blkno; 703 vp->v_cstart = lbn + 1; 704 vp->v_lastw = lbn; 705 return; 706 } 707 vp->v_clen = maxclen; 708 if (!async && maxclen == 0) { /* I/O not contiguous */ 709 vp->v_cstart = lbn + 1; 710 bawrite(bp); 711 } else { /* Wait for rest of cluster */ 712 vp->v_cstart = lbn; 713 bdwrite(bp); 714 } 715 } else if (lbn == vp->v_cstart + vp->v_clen) { 716 /* 717 * At end of cluster, write it out if seqcount tells us we 718 * are operating sequentially, otherwise let the buf or 719 * update daemon handle it. 720 */ 721 bdwrite(bp); 722 if (seqcount > 1) 723 cluster_wbuild_wb(vp, lblocksize, vp->v_cstart, vp->v_clen + 1); 724 vp->v_clen = 0; 725 vp->v_cstart = lbn + 1; 726 } else if (vm_page_count_severe()) { 727 /* 728 * We are low on memory, get it going NOW 729 */ 730 bawrite(bp); 731 } else { 732 /* 733 * In the middle of a cluster, so just delay the I/O for now. 734 */ 735 bdwrite(bp); 736 } 737 vp->v_lastw = lbn; 738 vp->v_lasta = bp->b_blkno; 739 } 740 741 742 /* 743 * This is an awful lot like cluster_rbuild...wish they could be combined. 744 * The last lbn argument is the current block on which I/O is being 745 * performed. Check to see that it doesn't fall in the middle of 746 * the current block (if last_bp == NULL). 747 */ 748 int 749 cluster_wbuild(vp, size, start_lbn, len) 750 struct vnode *vp; 751 long size; 752 daddr_t start_lbn; 753 int len; 754 { 755 struct buf *bp, *tbp; 756 int i, j, s; 757 int totalwritten = 0; 758 int dbsize = btodb(size); 759 760 GIANT_REQUIRED; 761 762 while (len > 0) { 763 s = splbio(); 764 /* 765 * If the buffer is not delayed-write (i.e. dirty), or it 766 * is delayed-write but either locked or inval, it cannot 767 * partake in the clustered write. 768 */ 769 VI_LOCK(vp); 770 if ((tbp = gbincore(vp, start_lbn)) == NULL || 771 (tbp->b_vflags & BV_BKGRDINPROG)) { 772 VI_UNLOCK(vp); 773 ++start_lbn; 774 --len; 775 splx(s); 776 continue; 777 } 778 if (BUF_LOCK(tbp, 779 LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, VI_MTX(vp))) { 780 ++start_lbn; 781 --len; 782 splx(s); 783 continue; 784 } 785 if ((tbp->b_flags & (B_INVAL | B_DELWRI)) != B_DELWRI) { 786 BUF_UNLOCK(tbp); 787 ++start_lbn; 788 --len; 789 splx(s); 790 continue; 791 } 792 bremfree(tbp); 793 tbp->b_flags &= ~B_DONE; 794 splx(s); 795 796 /* 797 * Extra memory in the buffer, punt on this buffer. 798 * XXX we could handle this in most cases, but we would 799 * have to push the extra memory down to after our max 800 * possible cluster size and then potentially pull it back 801 * up if the cluster was terminated prematurely--too much 802 * hassle. 803 */ 804 if (((tbp->b_flags & (B_CLUSTEROK | B_MALLOC | B_VMIO)) != 805 (B_CLUSTEROK | B_VMIO)) || 806 (tbp->b_bcount != tbp->b_bufsize) || 807 (tbp->b_bcount != size) || 808 (len == 1) || 809 ((bp = getpbuf(&cluster_pbuf_freecnt)) == NULL)) { 810 totalwritten += tbp->b_bufsize; 811 bawrite(tbp); 812 ++start_lbn; 813 --len; 814 continue; 815 } 816 817 /* 818 * We got a pbuf to make the cluster in. 819 * so initialise it. 820 */ 821 TAILQ_INIT(&bp->b_cluster.cluster_head); 822 bp->b_bcount = 0; 823 bp->b_magic = tbp->b_magic; 824 bp->b_op = tbp->b_op; 825 bp->b_bufsize = 0; 826 bp->b_npages = 0; 827 if (tbp->b_wcred != NOCRED) 828 bp->b_wcred = crhold(tbp->b_wcred); 829 830 bp->b_blkno = tbp->b_blkno; 831 bp->b_lblkno = tbp->b_lblkno; 832 bp->b_offset = tbp->b_offset; 833 834 /* 835 * We are synthesizing a buffer out of vm_page_t's, but 836 * if the block size is not page aligned then the starting 837 * address may not be either. Inherit the b_data offset 838 * from the original buffer. 839 */ 840 bp->b_data = (char *)((vm_offset_t)bp->b_data | 841 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 842 bp->b_flags |= B_CLUSTER | 843 (tbp->b_flags & (B_VMIO | B_NEEDCOMMIT)); 844 bp->b_iodone = cluster_callback; 845 pbgetvp(vp, bp); 846 /* 847 * From this location in the file, scan forward to see 848 * if there are buffers with adjacent data that need to 849 * be written as well. 850 */ 851 for (i = 0; i < len; ++i, ++start_lbn) { 852 if (i != 0) { /* If not the first buffer */ 853 s = splbio(); 854 /* 855 * If the adjacent data is not even in core it 856 * can't need to be written. 857 */ 858 VI_LOCK(vp); 859 if ((tbp = gbincore(vp, start_lbn)) == NULL || 860 (tbp->b_vflags & BV_BKGRDINPROG)) { 861 VI_UNLOCK(vp); 862 splx(s); 863 break; 864 } 865 866 /* 867 * If it IS in core, but has different 868 * characteristics, or is locked (which 869 * means it could be undergoing a background 870 * I/O or be in a weird state), then don't 871 * cluster with it. 872 */ 873 if (BUF_LOCK(tbp, 874 LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, 875 VI_MTX(vp))) { 876 splx(s); 877 break; 878 } 879 880 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK | 881 B_INVAL | B_DELWRI | B_NEEDCOMMIT)) 882 != (B_DELWRI | B_CLUSTEROK | 883 (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) || 884 tbp->b_wcred != bp->b_wcred) { 885 BUF_UNLOCK(tbp); 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 tbp->b_iocmd = BIO_WRITE; 916 buf_start(tbp); 917 } 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 VM_OBJECT_LOCK(tbp->b_object); 930 if (i != 0) { /* if not first buffer */ 931 for (j = 0; j < tbp->b_npages; j += 1) { 932 m = tbp->b_pages[j]; 933 if (m->flags & PG_BUSY) { 934 VM_OBJECT_UNLOCK( 935 tbp->b_object); 936 bqrelse(tbp); 937 goto finishcluster; 938 } 939 } 940 } 941 for (j = 0; j < tbp->b_npages; j += 1) { 942 m = tbp->b_pages[j]; 943 vm_page_io_start(m); 944 vm_object_pip_add(m->object, 1); 945 if ((bp->b_npages == 0) || 946 (bp->b_pages[bp->b_npages - 1] != m)) { 947 bp->b_pages[bp->b_npages] = m; 948 bp->b_npages++; 949 } 950 } 951 VM_OBJECT_UNLOCK(tbp->b_object); 952 } 953 bp->b_bcount += size; 954 bp->b_bufsize += size; 955 956 s = splbio(); 957 bundirty(tbp); 958 tbp->b_flags &= ~B_DONE; 959 tbp->b_ioflags &= ~BIO_ERROR; 960 tbp->b_flags |= B_ASYNC; 961 tbp->b_iocmd = BIO_WRITE; 962 reassignbuf(tbp); /* put on clean list */ 963 VI_LOCK(tbp->b_vp); 964 ++tbp->b_vp->v_numoutput; 965 VI_UNLOCK(tbp->b_vp); 966 splx(s); 967 BUF_KERNPROC(tbp); 968 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head, 969 tbp, b_cluster.cluster_entry); 970 } 971 finishcluster: 972 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 973 (vm_page_t *) bp->b_pages, bp->b_npages); 974 if (bp->b_bufsize > bp->b_kvasize) 975 panic( 976 "cluster_wbuild: b_bufsize(%ld) > b_kvasize(%d)\n", 977 bp->b_bufsize, bp->b_kvasize); 978 bp->b_kvasize = bp->b_bufsize; 979 totalwritten += bp->b_bufsize; 980 bp->b_dirtyoff = 0; 981 bp->b_dirtyend = bp->b_bufsize; 982 bawrite(bp); 983 984 len -= i; 985 } 986 return totalwritten; 987 } 988 989 /* 990 * Collect together all the buffers in a cluster. 991 * Plus add one additional buffer. 992 */ 993 static struct cluster_save * 994 cluster_collectbufs(vp, last_bp) 995 struct vnode *vp; 996 struct buf *last_bp; 997 { 998 struct cluster_save *buflist; 999 struct buf *bp; 1000 daddr_t lbn; 1001 int i, len; 1002 1003 len = vp->v_lastw - vp->v_cstart + 1; 1004 buflist = malloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist), 1005 M_SEGMENT, M_WAITOK); 1006 buflist->bs_nchildren = 0; 1007 buflist->bs_children = (struct buf **) (buflist + 1); 1008 for (lbn = vp->v_cstart, i = 0; i < len; lbn++, i++) { 1009 (void) bread(vp, lbn, last_bp->b_bcount, NOCRED, &bp); 1010 buflist->bs_children[i] = bp; 1011 if (bp->b_blkno == bp->b_lblkno) 1012 VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno, 1013 NULL, NULL); 1014 } 1015 buflist->bs_children[i] = bp = last_bp; 1016 if (bp->b_blkno == bp->b_lblkno) 1017 VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno, 1018 NULL, NULL); 1019 buflist->bs_nchildren = i + 1; 1020 return (buflist); 1021 }
Cache object: aabbd0db11ff85a40d41e3cc88fbfb4f
[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]