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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 * 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: releng/5.3/sys/kern/vfs_cluster.c 136588 2004-10-16 08:43:07Z cvs2svn $"); 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 * 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 * Read data to a buf, including read-ahead if we find this to be beneficial. 88 * cluster_read replaces bread. 89 */ 90 int 91 cluster_read(vp, filesize, lblkno, size, cred, totread, seqcount, bpp) 92 struct vnode *vp; 93 u_quad_t filesize; 94 daddr_t lblkno; 95 long size; 96 struct ucred *cred; 97 long totread; 98 int seqcount; 99 struct buf **bpp; 100 { 101 struct buf *bp, *rbp, *reqbp; 102 daddr_t blkno, origblkno; 103 int maxra, racluster; 104 int error, ncontig; 105 int i; 106 107 error = 0; 108 109 /* 110 * Try to limit the amount of read-ahead by a few 111 * ad-hoc parameters. This needs work!!! 112 */ 113 racluster = vp->v_mount->mnt_iosize_max / size; 114 maxra = seqcount; 115 maxra = min(read_max, maxra); 116 maxra = min(nbuf/8, maxra); 117 if (((u_quad_t)(lblkno + maxra + 1) * size) > filesize) 118 maxra = (filesize / size) - lblkno; 119 120 /* 121 * get the requested block 122 */ 123 *bpp = reqbp = bp = getblk(vp, lblkno, size, 0, 0, 0); 124 origblkno = lblkno; 125 126 /* 127 * if it is in the cache, then check to see if the reads have been 128 * sequential. If they have, then try some read-ahead, otherwise 129 * back-off on prospective read-aheads. 130 */ 131 if (bp->b_flags & B_CACHE) { 132 if (!seqcount) { 133 return 0; 134 } else if ((bp->b_flags & B_RAM) == 0) { 135 return 0; 136 } else { 137 int s; 138 bp->b_flags &= ~B_RAM; 139 /* 140 * We do the spl here so that there is no window 141 * between the incore and the b_usecount increment 142 * below. We opt to keep the spl out of the loop 143 * for efficiency. 144 */ 145 s = splbio(); 146 VI_LOCK(vp); 147 for (i = 1; i < maxra; i++) { 148 /* 149 * Stop if the buffer does not exist or it 150 * is invalid (about to go away?) 151 */ 152 rbp = gbincore(vp, lblkno+i); 153 if (rbp == NULL || (rbp->b_flags & B_INVAL)) 154 break; 155 156 /* 157 * Set another read-ahead mark so we know 158 * to check again. 159 */ 160 if (((i % racluster) == (racluster - 1)) || 161 (i == (maxra - 1))) 162 rbp->b_flags |= B_RAM; 163 } 164 VI_UNLOCK(vp); 165 splx(s); 166 if (i >= maxra) { 167 return 0; 168 } 169 lblkno += i; 170 } 171 reqbp = bp = NULL; 172 /* 173 * If it isn't in the cache, then get a chunk from 174 * disk if sequential, otherwise just get the block. 175 */ 176 } else { 177 off_t firstread = bp->b_offset; 178 int nblks; 179 180 KASSERT(bp->b_offset != NOOFFSET, 181 ("cluster_read: no buffer offset")); 182 183 ncontig = 0; 184 185 /* 186 * Compute the total number of blocks that we should read 187 * synchronously. 188 */ 189 if (firstread + totread > filesize) 190 totread = filesize - firstread; 191 nblks = howmany(totread, size); 192 if (nblks > racluster) 193 nblks = racluster; 194 195 /* 196 * Now compute the number of contiguous blocks. 197 */ 198 if (nblks > 1) { 199 error = VOP_BMAP(vp, lblkno, NULL, 200 &blkno, &ncontig, NULL); 201 /* 202 * If this failed to map just do the original block. 203 */ 204 if (error || blkno == -1) 205 ncontig = 0; 206 } 207 208 /* 209 * If we have contiguous data available do a cluster 210 * otherwise just read the requested block. 211 */ 212 if (ncontig) { 213 /* Account for our first block. */ 214 ncontig = min(ncontig + 1, nblks); 215 if (ncontig < nblks) 216 nblks = ncontig; 217 bp = cluster_rbuild(vp, filesize, lblkno, 218 blkno, size, nblks, bp); 219 lblkno += (bp->b_bufsize / size); 220 } else { 221 bp->b_flags |= B_RAM; 222 bp->b_iocmd = BIO_READ; 223 lblkno += 1; 224 } 225 } 226 227 /* 228 * handle the synchronous read so that it is available ASAP. 229 */ 230 if (bp) { 231 if ((bp->b_flags & B_CLUSTER) == 0) { 232 vfs_busy_pages(bp, 0); 233 } 234 bp->b_flags &= ~B_INVAL; 235 bp->b_ioflags &= ~BIO_ERROR; 236 if ((bp->b_flags & B_ASYNC) || bp->b_iodone != NULL) 237 BUF_KERNPROC(bp); 238 bp->b_iooffset = dbtob(bp->b_blkno); 239 error = VOP_STRATEGY(vp, bp); 240 curproc->p_stats->p_ru.ru_inblock++; 241 if (error) 242 return (error); 243 } 244 245 /* 246 * If we have been doing sequential I/O, then do some read-ahead. 247 */ 248 while (lblkno < (origblkno + maxra)) { 249 error = VOP_BMAP(vp, lblkno, NULL, &blkno, &ncontig, NULL); 250 if (error) 251 break; 252 253 if (blkno == -1) 254 break; 255 256 /* 257 * We could throttle ncontig here by maxra but we might as 258 * well read the data if it is contiguous. We're throttled 259 * by racluster anyway. 260 */ 261 if (ncontig) { 262 ncontig = min(ncontig + 1, racluster); 263 rbp = cluster_rbuild(vp, filesize, lblkno, blkno, 264 size, ncontig, NULL); 265 lblkno += (rbp->b_bufsize / size); 266 if (rbp->b_flags & B_DELWRI) { 267 bqrelse(rbp); 268 continue; 269 } 270 } else { 271 rbp = getblk(vp, lblkno, size, 0, 0, 0); 272 lblkno += 1; 273 if (rbp->b_flags & B_DELWRI) { 274 bqrelse(rbp); 275 continue; 276 } 277 rbp->b_flags |= B_ASYNC | B_RAM; 278 rbp->b_iocmd = BIO_READ; 279 rbp->b_blkno = blkno; 280 } 281 if (rbp->b_flags & B_CACHE) { 282 rbp->b_flags &= ~B_ASYNC; 283 bqrelse(rbp); 284 continue; 285 } 286 if ((rbp->b_flags & B_CLUSTER) == 0) { 287 vfs_busy_pages(rbp, 0); 288 } 289 rbp->b_flags &= ~B_INVAL; 290 rbp->b_ioflags &= ~BIO_ERROR; 291 if ((rbp->b_flags & B_ASYNC) || rbp->b_iodone != NULL) 292 BUF_KERNPROC(rbp); 293 rbp->b_iooffset = dbtob(rbp->b_blkno); 294 (void) VOP_STRATEGY(vp, rbp); 295 curproc->p_stats->p_ru.ru_inblock++; 296 } 297 298 if (reqbp) 299 return (bufwait(reqbp)); 300 else 301 return (error); 302 } 303 304 /* 305 * If blocks are contiguous on disk, use this to provide clustered 306 * read ahead. We will read as many blocks as possible sequentially 307 * and then parcel them up into logical blocks in the buffer hash table. 308 */ 309 static struct buf * 310 cluster_rbuild(vp, filesize, lbn, blkno, size, run, fbp) 311 struct vnode *vp; 312 u_quad_t filesize; 313 daddr_t lbn; 314 daddr_t blkno; 315 long size; 316 int run; 317 struct buf *fbp; 318 { 319 struct buf *bp, *tbp; 320 daddr_t bn; 321 int i, inc, j; 322 323 GIANT_REQUIRED; 324 325 KASSERT(size == vp->v_mount->mnt_stat.f_iosize, 326 ("cluster_rbuild: size %ld != filesize %jd\n", 327 size, (intmax_t)vp->v_mount->mnt_stat.f_iosize)); 328 329 /* 330 * avoid a division 331 */ 332 while ((u_quad_t) size * (lbn + run) > filesize) { 333 --run; 334 } 335 336 if (fbp) { 337 tbp = fbp; 338 tbp->b_iocmd = BIO_READ; 339 } else { 340 tbp = getblk(vp, lbn, size, 0, 0, 0); 341 if (tbp->b_flags & B_CACHE) 342 return tbp; 343 tbp->b_flags |= B_ASYNC | B_RAM; 344 tbp->b_iocmd = BIO_READ; 345 } 346 347 tbp->b_blkno = blkno; 348 if( (tbp->b_flags & B_MALLOC) || 349 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1) ) 350 return tbp; 351 352 bp = trypbuf(&cluster_pbuf_freecnt); 353 if (bp == 0) 354 return tbp; 355 356 /* 357 * We are synthesizing a buffer out of vm_page_t's, but 358 * if the block size is not page aligned then the starting 359 * address may not be either. Inherit the b_data offset 360 * from the original buffer. 361 */ 362 bp->b_data = (char *)((vm_offset_t)bp->b_data | 363 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 364 bp->b_flags = B_ASYNC | B_CLUSTER | B_VMIO; 365 bp->b_iocmd = BIO_READ; 366 bp->b_iodone = cluster_callback; 367 bp->b_blkno = blkno; 368 bp->b_lblkno = lbn; 369 bp->b_offset = tbp->b_offset; 370 KASSERT(bp->b_offset != NOOFFSET, ("cluster_rbuild: no buffer offset")); 371 pbgetvp(vp, bp); 372 373 TAILQ_INIT(&bp->b_cluster.cluster_head); 374 375 bp->b_bcount = 0; 376 bp->b_bufsize = 0; 377 bp->b_npages = 0; 378 379 inc = btodb(size); 380 for (bn = blkno, i = 0; i < run; ++i, bn += inc) { 381 if (i != 0) { 382 if ((bp->b_npages * PAGE_SIZE) + 383 round_page(size) > vp->v_mount->mnt_iosize_max) { 384 break; 385 } 386 387 tbp = getblk(vp, lbn + i, size, 0, 0, GB_LOCK_NOWAIT); 388 389 /* Don't wait around for locked bufs. */ 390 if (tbp == NULL) 391 break; 392 393 /* 394 * Stop scanning if the buffer is fully valid 395 * (marked B_CACHE), or locked (may be doing a 396 * background write), or if the buffer is not 397 * VMIO backed. The clustering code can only deal 398 * with VMIO-backed buffers. 399 */ 400 VI_LOCK(bp->b_vp); 401 if ((tbp->b_vflags & BV_BKGRDINPROG) || 402 (tbp->b_flags & B_CACHE) || 403 (tbp->b_flags & B_VMIO) == 0) { 404 VI_UNLOCK(bp->b_vp); 405 bqrelse(tbp); 406 break; 407 } 408 VI_UNLOCK(bp->b_vp); 409 410 /* 411 * The buffer must be completely invalid in order to 412 * take part in the cluster. If it is partially valid 413 * then we stop. 414 */ 415 VM_OBJECT_LOCK(tbp->b_object); 416 for (j = 0;j < tbp->b_npages; j++) { 417 VM_OBJECT_LOCK_ASSERT(tbp->b_pages[j]->object, 418 MA_OWNED); 419 if (tbp->b_pages[j]->valid) 420 break; 421 } 422 VM_OBJECT_UNLOCK(tbp->b_object); 423 if (j != tbp->b_npages) { 424 bqrelse(tbp); 425 break; 426 } 427 428 /* 429 * Set a read-ahead mark as appropriate 430 */ 431 if ((fbp && (i == 1)) || (i == (run - 1))) 432 tbp->b_flags |= B_RAM; 433 434 /* 435 * Set the buffer up for an async read (XXX should 436 * we do this only if we do not wind up brelse()ing?). 437 * Set the block number if it isn't set, otherwise 438 * if it is make sure it matches the block number we 439 * expect. 440 */ 441 tbp->b_flags |= B_ASYNC; 442 tbp->b_iocmd = BIO_READ; 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 VM_OBJECT_LOCK(tbp->b_object); 458 vm_page_lock_queues(); 459 for (j = 0; j < tbp->b_npages; j += 1) { 460 vm_page_t m; 461 m = tbp->b_pages[j]; 462 vm_page_io_start(m); 463 vm_object_pip_add(m->object, 1); 464 if ((bp->b_npages == 0) || 465 (bp->b_pages[bp->b_npages-1] != m)) { 466 bp->b_pages[bp->b_npages] = m; 467 bp->b_npages++; 468 } 469 if ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) 470 tbp->b_pages[j] = bogus_page; 471 } 472 vm_page_unlock_queues(); 473 VM_OBJECT_UNLOCK(tbp->b_object); 474 /* 475 * XXX shouldn't this be += size for both, like in 476 * cluster_wbuild()? 477 * 478 * Don't inherit tbp->b_bufsize as it may be larger due to 479 * a non-page-aligned size. Instead just aggregate using 480 * 'size'. 481 */ 482 if (tbp->b_bcount != size) 483 printf("warning: tbp->b_bcount wrong %ld vs %ld\n", tbp->b_bcount, size); 484 if (tbp->b_bufsize != size) 485 printf("warning: tbp->b_bufsize wrong %ld vs %ld\n", tbp->b_bufsize, size); 486 bp->b_bcount += size; 487 bp->b_bufsize += size; 488 } 489 490 /* 491 * Fully valid pages in the cluster are already good and do not need 492 * to be re-read from disk. Replace the page with bogus_page 493 */ 494 VM_OBJECT_LOCK(bp->b_object); 495 for (j = 0; j < bp->b_npages; j++) { 496 VM_OBJECT_LOCK_ASSERT(bp->b_pages[j]->object, MA_OWNED); 497 if ((bp->b_pages[j]->valid & VM_PAGE_BITS_ALL) == 498 VM_PAGE_BITS_ALL) { 499 bp->b_pages[j] = bogus_page; 500 } 501 } 502 VM_OBJECT_UNLOCK(bp->b_object); 503 if (bp->b_bufsize > bp->b_kvasize) 504 panic("cluster_rbuild: b_bufsize(%ld) > b_kvasize(%d)\n", 505 bp->b_bufsize, bp->b_kvasize); 506 bp->b_kvasize = bp->b_bufsize; 507 508 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 509 (vm_page_t *)bp->b_pages, bp->b_npages); 510 return (bp); 511 } 512 513 /* 514 * Cleanup after a clustered read or write. 515 * This is complicated by the fact that any of the buffers might have 516 * extra memory (if there were no empty buffer headers at allocbuf time) 517 * that we will need to shift around. 518 */ 519 void 520 cluster_callback(bp) 521 struct buf *bp; 522 { 523 struct buf *nbp, *tbp; 524 int error = 0; 525 526 GIANT_REQUIRED; 527 528 /* 529 * Must propogate errors to all the components. 530 */ 531 if (bp->b_ioflags & BIO_ERROR) 532 error = bp->b_error; 533 534 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages); 535 /* 536 * Move memory from the large cluster buffer into the component 537 * buffers and mark IO as done on these. 538 */ 539 for (tbp = TAILQ_FIRST(&bp->b_cluster.cluster_head); 540 tbp; tbp = nbp) { 541 nbp = TAILQ_NEXT(&tbp->b_cluster, cluster_entry); 542 if (error) { 543 tbp->b_ioflags |= BIO_ERROR; 544 tbp->b_error = error; 545 } else { 546 tbp->b_dirtyoff = tbp->b_dirtyend = 0; 547 tbp->b_flags &= ~B_INVAL; 548 tbp->b_ioflags &= ~BIO_ERROR; 549 /* 550 * XXX the bdwrite()/bqrelse() issued during 551 * cluster building clears B_RELBUF (see bqrelse() 552 * comment). If direct I/O was specified, we have 553 * to restore it here to allow the buffer and VM 554 * to be freed. 555 */ 556 if (tbp->b_flags & B_DIRECT) 557 tbp->b_flags |= B_RELBUF; 558 } 559 bufdone(tbp); 560 } 561 relpbuf(bp, &cluster_pbuf_freecnt); 562 } 563 564 /* 565 * cluster_wbuild_wb: 566 * 567 * Implement modified write build for cluster. 568 * 569 * write_behind = 0 write behind disabled 570 * write_behind = 1 write behind normal (default) 571 * write_behind = 2 write behind backed-off 572 */ 573 574 static __inline int 575 cluster_wbuild_wb(struct vnode *vp, long size, daddr_t start_lbn, int len) 576 { 577 int r = 0; 578 579 switch(write_behind) { 580 case 2: 581 if (start_lbn < len) 582 break; 583 start_lbn -= len; 584 /* FALLTHROUGH */ 585 case 1: 586 r = cluster_wbuild(vp, size, start_lbn, len); 587 /* FALLTHROUGH */ 588 default: 589 /* FALLTHROUGH */ 590 break; 591 } 592 return(r); 593 } 594 595 /* 596 * Do clustered write for FFS. 597 * 598 * Three cases: 599 * 1. Write is not sequential (write asynchronously) 600 * Write is sequential: 601 * 2. beginning of cluster - begin cluster 602 * 3. middle of a cluster - add to cluster 603 * 4. end of a cluster - asynchronously write cluster 604 */ 605 void 606 cluster_write(bp, filesize, seqcount) 607 struct buf *bp; 608 u_quad_t filesize; 609 int seqcount; 610 { 611 struct vnode *vp; 612 daddr_t lbn; 613 int maxclen, cursize; 614 int lblocksize; 615 int async; 616 617 vp = bp->b_vp; 618 if (vp->v_type == VREG) { 619 async = vp->v_mount->mnt_flag & MNT_ASYNC; 620 lblocksize = vp->v_mount->mnt_stat.f_iosize; 621 } else { 622 async = 0; 623 lblocksize = bp->b_bufsize; 624 } 625 lbn = bp->b_lblkno; 626 KASSERT(bp->b_offset != NOOFFSET, ("cluster_write: no buffer offset")); 627 628 /* Initialize vnode to beginning of file. */ 629 if (lbn == 0) 630 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0; 631 632 if (vp->v_clen == 0 || lbn != vp->v_lastw + 1 || 633 (bp->b_blkno != vp->v_lasta + btodb(lblocksize))) { 634 maxclen = vp->v_mount->mnt_iosize_max / lblocksize - 1; 635 if (vp->v_clen != 0) { 636 /* 637 * Next block is not sequential. 638 * 639 * If we are not writing at end of file, the process 640 * seeked to another point in the file since its last 641 * write, or we have reached our maximum cluster size, 642 * then push the previous cluster. Otherwise try 643 * reallocating to make it sequential. 644 * 645 * Change to algorithm: only push previous cluster if 646 * it was sequential from the point of view of the 647 * seqcount heuristic, otherwise leave the buffer 648 * intact so we can potentially optimize the I/O 649 * later on in the buf_daemon or update daemon 650 * flush. 651 */ 652 cursize = vp->v_lastw - vp->v_cstart + 1; 653 if (((u_quad_t) bp->b_offset + lblocksize) != filesize || 654 lbn != vp->v_lastw + 1 || vp->v_clen <= cursize) { 655 if (!async && seqcount > 0) { 656 cluster_wbuild_wb(vp, lblocksize, 657 vp->v_cstart, cursize); 658 } 659 } else { 660 struct buf **bpp, **endbp; 661 struct cluster_save *buflist; 662 663 buflist = cluster_collectbufs(vp, bp); 664 endbp = &buflist->bs_children 665 [buflist->bs_nchildren - 1]; 666 if (VOP_REALLOCBLKS(vp, buflist)) { 667 /* 668 * Failed, push the previous cluster 669 * if *really* writing sequentially 670 * in the logical file (seqcount > 1), 671 * otherwise delay it in the hopes that 672 * the low level disk driver can 673 * optimize the write ordering. 674 */ 675 for (bpp = buflist->bs_children; 676 bpp < endbp; bpp++) 677 brelse(*bpp); 678 free(buflist, M_SEGMENT); 679 if (seqcount > 1) { 680 cluster_wbuild_wb(vp, 681 lblocksize, vp->v_cstart, 682 cursize); 683 } 684 } else { 685 /* 686 * Succeeded, keep building cluster. 687 */ 688 for (bpp = buflist->bs_children; 689 bpp <= endbp; bpp++) 690 bdwrite(*bpp); 691 free(buflist, M_SEGMENT); 692 vp->v_lastw = lbn; 693 vp->v_lasta = bp->b_blkno; 694 return; 695 } 696 } 697 } 698 /* 699 * Consider beginning a cluster. If at end of file, make 700 * cluster as large as possible, otherwise find size of 701 * existing cluster. 702 */ 703 if ((vp->v_type == VREG) && 704 ((u_quad_t) bp->b_offset + lblocksize) != filesize && 705 (bp->b_blkno == bp->b_lblkno) && 706 (VOP_BMAP(vp, lbn, NULL, &bp->b_blkno, &maxclen, NULL) || 707 bp->b_blkno == -1)) { 708 bawrite(bp); 709 vp->v_clen = 0; 710 vp->v_lasta = bp->b_blkno; 711 vp->v_cstart = lbn + 1; 712 vp->v_lastw = lbn; 713 return; 714 } 715 vp->v_clen = maxclen; 716 if (!async && maxclen == 0) { /* I/O not contiguous */ 717 vp->v_cstart = lbn + 1; 718 bawrite(bp); 719 } else { /* Wait for rest of cluster */ 720 vp->v_cstart = lbn; 721 bdwrite(bp); 722 } 723 } else if (lbn == vp->v_cstart + vp->v_clen) { 724 /* 725 * At end of cluster, write it out if seqcount tells us we 726 * are operating sequentially, otherwise let the buf or 727 * update daemon handle it. 728 */ 729 bdwrite(bp); 730 if (seqcount > 1) 731 cluster_wbuild_wb(vp, lblocksize, vp->v_cstart, vp->v_clen + 1); 732 vp->v_clen = 0; 733 vp->v_cstart = lbn + 1; 734 } else if (vm_page_count_severe()) { 735 /* 736 * We are low on memory, get it going NOW 737 */ 738 bawrite(bp); 739 } else { 740 /* 741 * In the middle of a cluster, so just delay the I/O for now. 742 */ 743 bdwrite(bp); 744 } 745 vp->v_lastw = lbn; 746 vp->v_lasta = bp->b_blkno; 747 } 748 749 750 /* 751 * This is an awful lot like cluster_rbuild...wish they could be combined. 752 * The last lbn argument is the current block on which I/O is being 753 * performed. Check to see that it doesn't fall in the middle of 754 * the current block (if last_bp == NULL). 755 */ 756 int 757 cluster_wbuild(vp, size, start_lbn, len) 758 struct vnode *vp; 759 long size; 760 daddr_t start_lbn; 761 int len; 762 { 763 struct buf *bp, *tbp; 764 int i, j, s; 765 int totalwritten = 0; 766 int dbsize = btodb(size); 767 768 GIANT_REQUIRED; 769 770 while (len > 0) { 771 s = splbio(); 772 /* 773 * If the buffer is not delayed-write (i.e. dirty), or it 774 * is delayed-write but either locked or inval, it cannot 775 * partake in the clustered write. 776 */ 777 VI_LOCK(vp); 778 if ((tbp = gbincore(vp, start_lbn)) == NULL || 779 (tbp->b_vflags & BV_BKGRDINPROG)) { 780 VI_UNLOCK(vp); 781 ++start_lbn; 782 --len; 783 splx(s); 784 continue; 785 } 786 if (BUF_LOCK(tbp, 787 LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, VI_MTX(vp))) { 788 ++start_lbn; 789 --len; 790 splx(s); 791 continue; 792 } 793 if ((tbp->b_flags & (B_INVAL | B_DELWRI)) != B_DELWRI) { 794 BUF_UNLOCK(tbp); 795 ++start_lbn; 796 --len; 797 splx(s); 798 continue; 799 } 800 bremfree(tbp); 801 tbp->b_flags &= ~B_DONE; 802 splx(s); 803 804 /* 805 * Extra memory in the buffer, punt on this buffer. 806 * XXX we could handle this in most cases, but we would 807 * have to push the extra memory down to after our max 808 * possible cluster size and then potentially pull it back 809 * up if the cluster was terminated prematurely--too much 810 * hassle. 811 */ 812 if (((tbp->b_flags & (B_CLUSTEROK | B_MALLOC | B_VMIO)) != 813 (B_CLUSTEROK | B_VMIO)) || 814 (tbp->b_bcount != tbp->b_bufsize) || 815 (tbp->b_bcount != size) || 816 (len == 1) || 817 ((bp = getpbuf(&cluster_pbuf_freecnt)) == NULL)) { 818 totalwritten += tbp->b_bufsize; 819 bawrite(tbp); 820 ++start_lbn; 821 --len; 822 continue; 823 } 824 825 /* 826 * We got a pbuf to make the cluster in. 827 * so initialise it. 828 */ 829 TAILQ_INIT(&bp->b_cluster.cluster_head); 830 bp->b_bcount = 0; 831 bp->b_magic = tbp->b_magic; 832 bp->b_op = tbp->b_op; 833 bp->b_bufsize = 0; 834 bp->b_npages = 0; 835 if (tbp->b_wcred != NOCRED) 836 bp->b_wcred = crhold(tbp->b_wcred); 837 838 bp->b_blkno = tbp->b_blkno; 839 bp->b_lblkno = tbp->b_lblkno; 840 bp->b_offset = tbp->b_offset; 841 842 /* 843 * We are synthesizing a buffer out of vm_page_t's, but 844 * if the block size is not page aligned then the starting 845 * address may not be either. Inherit the b_data offset 846 * from the original buffer. 847 */ 848 bp->b_data = (char *)((vm_offset_t)bp->b_data | 849 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 850 bp->b_flags |= B_CLUSTER | 851 (tbp->b_flags & (B_VMIO | B_NEEDCOMMIT)); 852 bp->b_iodone = cluster_callback; 853 pbgetvp(vp, bp); 854 /* 855 * From this location in the file, scan forward to see 856 * if there are buffers with adjacent data that need to 857 * be written as well. 858 */ 859 for (i = 0; i < len; ++i, ++start_lbn) { 860 if (i != 0) { /* If not the first buffer */ 861 s = splbio(); 862 /* 863 * If the adjacent data is not even in core it 864 * can't need to be written. 865 */ 866 VI_LOCK(vp); 867 if ((tbp = gbincore(vp, start_lbn)) == NULL || 868 (tbp->b_vflags & BV_BKGRDINPROG)) { 869 VI_UNLOCK(vp); 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 (BUF_LOCK(tbp, 882 LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, 883 VI_MTX(vp))) { 884 splx(s); 885 break; 886 } 887 888 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK | 889 B_INVAL | B_DELWRI | B_NEEDCOMMIT)) 890 != (B_DELWRI | B_CLUSTEROK | 891 (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) || 892 tbp->b_wcred != bp->b_wcred) { 893 BUF_UNLOCK(tbp); 894 splx(s); 895 break; 896 } 897 898 /* 899 * Check that the combined cluster 900 * would make sense with regard to pages 901 * and would not be too large 902 */ 903 if ((tbp->b_bcount != size) || 904 ((bp->b_blkno + (dbsize * i)) != 905 tbp->b_blkno) || 906 ((tbp->b_npages + bp->b_npages) > 907 (vp->v_mount->mnt_iosize_max / PAGE_SIZE))) { 908 BUF_UNLOCK(tbp); 909 splx(s); 910 break; 911 } 912 /* 913 * Ok, it's passed all the tests, 914 * so remove it from the free list 915 * and mark it busy. We will use it. 916 */ 917 bremfree(tbp); 918 tbp->b_flags &= ~B_DONE; 919 splx(s); 920 } /* end of code for non-first buffers only */ 921 /* check for latent dependencies to be handled */ 922 if ((LIST_FIRST(&tbp->b_dep)) != NULL) { 923 tbp->b_iocmd = BIO_WRITE; 924 buf_start(tbp); 925 } 926 /* 927 * If the IO is via the VM then we do some 928 * special VM hackery (yuck). Since the buffer's 929 * block size may not be page-aligned it is possible 930 * for a page to be shared between two buffers. We 931 * have to get rid of the duplication when building 932 * the cluster. 933 */ 934 if (tbp->b_flags & B_VMIO) { 935 vm_page_t m; 936 937 if (i != 0) { /* if not first buffer */ 938 for (j = 0; j < tbp->b_npages; j += 1) { 939 m = tbp->b_pages[j]; 940 if (m->flags & PG_BUSY) { 941 bqrelse(tbp); 942 goto finishcluster; 943 } 944 } 945 } 946 if (tbp->b_object != NULL) 947 VM_OBJECT_LOCK(tbp->b_object); 948 vm_page_lock_queues(); 949 for (j = 0; j < tbp->b_npages; j += 1) { 950 m = tbp->b_pages[j]; 951 vm_page_io_start(m); 952 vm_object_pip_add(m->object, 1); 953 if ((bp->b_npages == 0) || 954 (bp->b_pages[bp->b_npages - 1] != m)) { 955 bp->b_pages[bp->b_npages] = m; 956 bp->b_npages++; 957 } 958 } 959 vm_page_unlock_queues(); 960 if (tbp->b_object != NULL) 961 VM_OBJECT_UNLOCK(tbp->b_object); 962 } 963 bp->b_bcount += size; 964 bp->b_bufsize += size; 965 966 s = splbio(); 967 bundirty(tbp); 968 tbp->b_flags &= ~B_DONE; 969 tbp->b_ioflags &= ~BIO_ERROR; 970 tbp->b_flags |= B_ASYNC; 971 tbp->b_iocmd = BIO_WRITE; 972 reassignbuf(tbp); /* put on clean list */ 973 VI_LOCK(tbp->b_vp); 974 ++tbp->b_vp->v_numoutput; 975 VI_UNLOCK(tbp->b_vp); 976 splx(s); 977 BUF_KERNPROC(tbp); 978 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head, 979 tbp, b_cluster.cluster_entry); 980 } 981 finishcluster: 982 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 983 (vm_page_t *) bp->b_pages, bp->b_npages); 984 if (bp->b_bufsize > bp->b_kvasize) 985 panic( 986 "cluster_wbuild: b_bufsize(%ld) > b_kvasize(%d)\n", 987 bp->b_bufsize, bp->b_kvasize); 988 bp->b_kvasize = bp->b_bufsize; 989 totalwritten += bp->b_bufsize; 990 bp->b_dirtyoff = 0; 991 bp->b_dirtyend = bp->b_bufsize; 992 bawrite(bp); 993 994 len -= i; 995 } 996 return totalwritten; 997 } 998 999 /* 1000 * Collect together all the buffers in a cluster. 1001 * Plus add one additional buffer. 1002 */ 1003 static struct cluster_save * 1004 cluster_collectbufs(vp, last_bp) 1005 struct vnode *vp; 1006 struct buf *last_bp; 1007 { 1008 struct cluster_save *buflist; 1009 struct buf *bp; 1010 daddr_t lbn; 1011 int i, len; 1012 1013 len = vp->v_lastw - vp->v_cstart + 1; 1014 buflist = malloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist), 1015 M_SEGMENT, M_WAITOK); 1016 buflist->bs_nchildren = 0; 1017 buflist->bs_children = (struct buf **) (buflist + 1); 1018 for (lbn = vp->v_cstart, i = 0; i < len; lbn++, i++) { 1019 (void) bread(vp, lbn, last_bp->b_bcount, NOCRED, &bp); 1020 buflist->bs_children[i] = bp; 1021 if (bp->b_blkno == bp->b_lblkno) 1022 VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno, 1023 NULL, NULL); 1024 } 1025 buflist->bs_children[i] = bp = last_bp; 1026 if (bp->b_blkno == bp->b_lblkno) 1027 VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno, 1028 NULL, NULL); 1029 buflist->bs_nchildren = i + 1; 1030 return (buflist); 1031 }
Cache object: 3cc3ceb938ec591b3b00b88e80d3657b
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