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("$FreeBSD$"); 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->v_bufobj, 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 bstrategy(bp); 240 curproc->p_stats->p_ru.ru_inblock++; 241 } 242 243 /* 244 * If we have been doing sequential I/O, then do some read-ahead. 245 */ 246 while (lblkno < (origblkno + maxra)) { 247 error = VOP_BMAP(vp, lblkno, NULL, &blkno, &ncontig, NULL); 248 if (error) 249 break; 250 251 if (blkno == -1) 252 break; 253 254 /* 255 * We could throttle ncontig here by maxra but we might as 256 * well read the data if it is contiguous. We're throttled 257 * by racluster anyway. 258 */ 259 if (ncontig) { 260 ncontig = min(ncontig + 1, racluster); 261 rbp = cluster_rbuild(vp, filesize, lblkno, blkno, 262 size, ncontig, NULL); 263 lblkno += (rbp->b_bufsize / size); 264 if (rbp->b_flags & B_DELWRI) { 265 bqrelse(rbp); 266 continue; 267 } 268 } else { 269 rbp = getblk(vp, lblkno, size, 0, 0, 0); 270 lblkno += 1; 271 if (rbp->b_flags & B_DELWRI) { 272 bqrelse(rbp); 273 continue; 274 } 275 rbp->b_flags |= B_ASYNC | B_RAM; 276 rbp->b_iocmd = BIO_READ; 277 rbp->b_blkno = blkno; 278 } 279 if (rbp->b_flags & B_CACHE) { 280 rbp->b_flags &= ~B_ASYNC; 281 bqrelse(rbp); 282 continue; 283 } 284 if ((rbp->b_flags & B_CLUSTER) == 0) { 285 vfs_busy_pages(rbp, 0); 286 } 287 rbp->b_flags &= ~B_INVAL; 288 rbp->b_ioflags &= ~BIO_ERROR; 289 if ((rbp->b_flags & B_ASYNC) || rbp->b_iodone != NULL) 290 BUF_KERNPROC(rbp); 291 rbp->b_iooffset = dbtob(rbp->b_blkno); 292 bstrategy(rbp); 293 curproc->p_stats->p_ru.ru_inblock++; 294 } 295 296 if (reqbp) 297 return (bufwait(reqbp)); 298 else 299 return (error); 300 } 301 302 /* 303 * If blocks are contiguous on disk, use this to provide clustered 304 * read ahead. We will read as many blocks as possible sequentially 305 * and then parcel them up into logical blocks in the buffer hash table. 306 */ 307 static struct buf * 308 cluster_rbuild(vp, filesize, lbn, blkno, size, run, fbp) 309 struct vnode *vp; 310 u_quad_t filesize; 311 daddr_t lbn; 312 daddr_t blkno; 313 long size; 314 int run; 315 struct buf *fbp; 316 { 317 struct buf *bp, *tbp; 318 daddr_t bn; 319 int i, inc, j; 320 321 GIANT_REQUIRED; 322 323 KASSERT(size == vp->v_mount->mnt_stat.f_iosize, 324 ("cluster_rbuild: size %ld != filesize %jd\n", 325 size, (intmax_t)vp->v_mount->mnt_stat.f_iosize)); 326 327 /* 328 * avoid a division 329 */ 330 while ((u_quad_t) size * (lbn + run) > filesize) { 331 --run; 332 } 333 334 if (fbp) { 335 tbp = fbp; 336 tbp->b_iocmd = BIO_READ; 337 } else { 338 tbp = getblk(vp, lbn, size, 0, 0, 0); 339 if (tbp->b_flags & B_CACHE) 340 return tbp; 341 tbp->b_flags |= B_ASYNC | B_RAM; 342 tbp->b_iocmd = BIO_READ; 343 } 344 345 tbp->b_blkno = blkno; 346 if( (tbp->b_flags & B_MALLOC) || 347 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1) ) 348 return tbp; 349 350 bp = trypbuf(&cluster_pbuf_freecnt); 351 if (bp == 0) 352 return tbp; 353 354 /* 355 * We are synthesizing a buffer out of vm_page_t's, but 356 * if the block size is not page aligned then the starting 357 * address may not be either. Inherit the b_data offset 358 * from the original buffer. 359 */ 360 bp->b_data = (char *)((vm_offset_t)bp->b_data | 361 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 362 bp->b_flags = B_ASYNC | B_CLUSTER | B_VMIO; 363 bp->b_iocmd = BIO_READ; 364 bp->b_iodone = cluster_callback; 365 bp->b_blkno = blkno; 366 bp->b_lblkno = lbn; 367 bp->b_offset = tbp->b_offset; 368 KASSERT(bp->b_offset != NOOFFSET, ("cluster_rbuild: no buffer offset")); 369 pbgetvp(vp, bp); 370 371 TAILQ_INIT(&bp->b_cluster.cluster_head); 372 373 bp->b_bcount = 0; 374 bp->b_bufsize = 0; 375 bp->b_npages = 0; 376 377 inc = btodb(size); 378 for (bn = blkno, i = 0; i < run; ++i, bn += inc) { 379 if (i != 0) { 380 if ((bp->b_npages * PAGE_SIZE) + 381 round_page(size) > vp->v_mount->mnt_iosize_max) { 382 break; 383 } 384 385 tbp = getblk(vp, lbn + i, size, 0, 0, GB_LOCK_NOWAIT); 386 387 /* Don't wait around for locked bufs. */ 388 if (tbp == NULL) 389 break; 390 391 /* 392 * Stop scanning if the buffer is fully valid 393 * (marked B_CACHE), or locked (may be doing a 394 * background write), or if the buffer is not 395 * VMIO backed. The clustering code can only deal 396 * with VMIO-backed buffers. 397 */ 398 VI_LOCK(vp); 399 if ((tbp->b_vflags & BV_BKGRDINPROG) || 400 (tbp->b_flags & B_CACHE) || 401 (tbp->b_flags & B_VMIO) == 0) { 402 VI_UNLOCK(vp); 403 bqrelse(tbp); 404 break; 405 } 406 VI_UNLOCK(vp); 407 408 /* 409 * The buffer must be completely invalid in order to 410 * take part in the cluster. If it is partially valid 411 * then we stop. 412 */ 413 VM_OBJECT_LOCK(tbp->b_bufobj->bo_object); 414 for (j = 0;j < tbp->b_npages; j++) { 415 VM_OBJECT_LOCK_ASSERT(tbp->b_pages[j]->object, 416 MA_OWNED); 417 if (tbp->b_pages[j]->valid) 418 break; 419 } 420 VM_OBJECT_UNLOCK(tbp->b_bufobj->bo_object); 421 if (j != tbp->b_npages) { 422 bqrelse(tbp); 423 break; 424 } 425 426 /* 427 * Set a read-ahead mark as appropriate 428 */ 429 if ((fbp && (i == 1)) || (i == (run - 1))) 430 tbp->b_flags |= B_RAM; 431 432 /* 433 * Set the buffer up for an async read (XXX should 434 * we do this only if we do not wind up brelse()ing?). 435 * Set the block number if it isn't set, otherwise 436 * if it is make sure it matches the block number we 437 * expect. 438 */ 439 tbp->b_flags |= B_ASYNC; 440 tbp->b_iocmd = BIO_READ; 441 if (tbp->b_blkno == tbp->b_lblkno) { 442 tbp->b_blkno = bn; 443 } else if (tbp->b_blkno != bn) { 444 brelse(tbp); 445 break; 446 } 447 } 448 /* 449 * XXX fbp from caller may not be B_ASYNC, but we are going 450 * to biodone() it in cluster_callback() anyway 451 */ 452 BUF_KERNPROC(tbp); 453 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head, 454 tbp, b_cluster.cluster_entry); 455 VM_OBJECT_LOCK(tbp->b_bufobj->bo_object); 456 vm_page_lock_queues(); 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 vm_page_unlock_queues(); 471 VM_OBJECT_UNLOCK(tbp->b_bufobj->bo_object); 472 /* 473 * XXX shouldn't this be += size for both, like in 474 * cluster_wbuild()? 475 * 476 * Don't inherit tbp->b_bufsize as it may be larger due to 477 * a non-page-aligned size. Instead just aggregate using 478 * 'size'. 479 */ 480 if (tbp->b_bcount != size) 481 printf("warning: tbp->b_bcount wrong %ld vs %ld\n", tbp->b_bcount, size); 482 if (tbp->b_bufsize != size) 483 printf("warning: tbp->b_bufsize wrong %ld vs %ld\n", tbp->b_bufsize, size); 484 bp->b_bcount += size; 485 bp->b_bufsize += size; 486 } 487 488 /* 489 * Fully valid pages in the cluster are already good and do not need 490 * to be re-read from disk. Replace the page with bogus_page 491 */ 492 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 493 for (j = 0; j < bp->b_npages; j++) { 494 VM_OBJECT_LOCK_ASSERT(bp->b_pages[j]->object, MA_OWNED); 495 if ((bp->b_pages[j]->valid & VM_PAGE_BITS_ALL) == 496 VM_PAGE_BITS_ALL) { 497 bp->b_pages[j] = bogus_page; 498 } 499 } 500 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 501 if (bp->b_bufsize > bp->b_kvasize) 502 panic("cluster_rbuild: b_bufsize(%ld) > b_kvasize(%d)\n", 503 bp->b_bufsize, bp->b_kvasize); 504 bp->b_kvasize = bp->b_bufsize; 505 506 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 507 (vm_page_t *)bp->b_pages, bp->b_npages); 508 return (bp); 509 } 510 511 /* 512 * Cleanup after a clustered read or write. 513 * This is complicated by the fact that any of the buffers might have 514 * extra memory (if there were no empty buffer headers at allocbuf time) 515 * that we will need to shift around. 516 */ 517 void 518 cluster_callback(bp) 519 struct buf *bp; 520 { 521 struct buf *nbp, *tbp; 522 int error = 0; 523 524 GIANT_REQUIRED; 525 526 /* 527 * Must propogate errors to all the components. 528 */ 529 if (bp->b_ioflags & BIO_ERROR) 530 error = bp->b_error; 531 532 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages); 533 /* 534 * Move memory from the large cluster buffer into the component 535 * buffers and mark IO as done on these. 536 */ 537 for (tbp = TAILQ_FIRST(&bp->b_cluster.cluster_head); 538 tbp; tbp = nbp) { 539 nbp = TAILQ_NEXT(&tbp->b_cluster, cluster_entry); 540 if (error) { 541 tbp->b_ioflags |= BIO_ERROR; 542 tbp->b_error = error; 543 } else { 544 tbp->b_dirtyoff = tbp->b_dirtyend = 0; 545 tbp->b_flags &= ~B_INVAL; 546 tbp->b_ioflags &= ~BIO_ERROR; 547 /* 548 * XXX the bdwrite()/bqrelse() issued during 549 * cluster building clears B_RELBUF (see bqrelse() 550 * comment). If direct I/O was specified, we have 551 * to restore it here to allow the buffer and VM 552 * to be freed. 553 */ 554 if (tbp->b_flags & B_DIRECT) 555 tbp->b_flags |= B_RELBUF; 556 } 557 bufdone(tbp); 558 } 559 pbrelvp(bp); 560 relpbuf(bp, &cluster_pbuf_freecnt); 561 } 562 563 /* 564 * cluster_wbuild_wb: 565 * 566 * Implement modified write build for cluster. 567 * 568 * write_behind = 0 write behind disabled 569 * write_behind = 1 write behind normal (default) 570 * write_behind = 2 write behind backed-off 571 */ 572 573 static __inline int 574 cluster_wbuild_wb(struct vnode *vp, long size, daddr_t start_lbn, int len) 575 { 576 int r = 0; 577 578 switch(write_behind) { 579 case 2: 580 if (start_lbn < len) 581 break; 582 start_lbn -= len; 583 /* FALLTHROUGH */ 584 case 1: 585 r = cluster_wbuild(vp, size, start_lbn, len); 586 /* FALLTHROUGH */ 587 default: 588 /* FALLTHROUGH */ 589 break; 590 } 591 return(r); 592 } 593 594 /* 595 * Do clustered write for FFS. 596 * 597 * Three cases: 598 * 1. Write is not sequential (write asynchronously) 599 * Write is sequential: 600 * 2. beginning of cluster - begin cluster 601 * 3. middle of a cluster - add to cluster 602 * 4. end of a cluster - asynchronously write cluster 603 */ 604 void 605 cluster_write(struct vnode *vp, struct buf *bp, u_quad_t filesize, int seqcount) 606 { 607 daddr_t lbn; 608 int maxclen, cursize; 609 int lblocksize; 610 int async; 611 612 if (vp->v_type == VREG) { 613 async = vp->v_mount->mnt_flag & MNT_ASYNC; 614 lblocksize = vp->v_mount->mnt_stat.f_iosize; 615 } else { 616 async = 0; 617 lblocksize = bp->b_bufsize; 618 } 619 lbn = bp->b_lblkno; 620 KASSERT(bp->b_offset != NOOFFSET, ("cluster_write: no buffer offset")); 621 622 /* Initialize vnode to beginning of file. */ 623 if (lbn == 0) 624 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0; 625 626 if (vp->v_clen == 0 || lbn != vp->v_lastw + 1 || 627 (bp->b_blkno != vp->v_lasta + btodb(lblocksize))) { 628 maxclen = vp->v_mount->mnt_iosize_max / lblocksize - 1; 629 if (vp->v_clen != 0) { 630 /* 631 * Next block is not sequential. 632 * 633 * If we are not writing at end of file, the process 634 * seeked to another point in the file since its last 635 * write, or we have reached our maximum cluster size, 636 * then push the previous cluster. Otherwise try 637 * reallocating to make it sequential. 638 * 639 * Change to algorithm: only push previous cluster if 640 * it was sequential from the point of view of the 641 * seqcount heuristic, otherwise leave the buffer 642 * intact so we can potentially optimize the I/O 643 * later on in the buf_daemon or update daemon 644 * flush. 645 */ 646 cursize = vp->v_lastw - vp->v_cstart + 1; 647 if (((u_quad_t) bp->b_offset + lblocksize) != filesize || 648 lbn != vp->v_lastw + 1 || vp->v_clen <= cursize) { 649 if (!async && seqcount > 0) { 650 cluster_wbuild_wb(vp, lblocksize, 651 vp->v_cstart, cursize); 652 } 653 } else { 654 struct buf **bpp, **endbp; 655 struct cluster_save *buflist; 656 657 buflist = cluster_collectbufs(vp, bp); 658 endbp = &buflist->bs_children 659 [buflist->bs_nchildren - 1]; 660 if (VOP_REALLOCBLKS(vp, buflist)) { 661 /* 662 * Failed, push the previous cluster 663 * if *really* writing sequentially 664 * in the logical file (seqcount > 1), 665 * otherwise delay it in the hopes that 666 * the low level disk driver can 667 * optimize the write ordering. 668 */ 669 for (bpp = buflist->bs_children; 670 bpp < endbp; bpp++) 671 brelse(*bpp); 672 free(buflist, M_SEGMENT); 673 if (seqcount > 1) { 674 cluster_wbuild_wb(vp, 675 lblocksize, vp->v_cstart, 676 cursize); 677 } 678 } else { 679 /* 680 * Succeeded, keep building cluster. 681 */ 682 for (bpp = buflist->bs_children; 683 bpp <= endbp; bpp++) 684 bdwrite(*bpp); 685 free(buflist, M_SEGMENT); 686 vp->v_lastw = lbn; 687 vp->v_lasta = bp->b_blkno; 688 return; 689 } 690 } 691 } 692 /* 693 * Consider beginning a cluster. If at end of file, make 694 * cluster as large as possible, otherwise find size of 695 * existing cluster. 696 */ 697 if ((vp->v_type == VREG) && 698 ((u_quad_t) bp->b_offset + lblocksize) != filesize && 699 (bp->b_blkno == bp->b_lblkno) && 700 (VOP_BMAP(vp, lbn, NULL, &bp->b_blkno, &maxclen, NULL) || 701 bp->b_blkno == -1)) { 702 bawrite(bp); 703 vp->v_clen = 0; 704 vp->v_lasta = bp->b_blkno; 705 vp->v_cstart = lbn + 1; 706 vp->v_lastw = lbn; 707 return; 708 } 709 vp->v_clen = maxclen; 710 if (!async && maxclen == 0) { /* I/O not contiguous */ 711 vp->v_cstart = lbn + 1; 712 bawrite(bp); 713 } else { /* Wait for rest of cluster */ 714 vp->v_cstart = lbn; 715 bdwrite(bp); 716 } 717 } else if (lbn == vp->v_cstart + vp->v_clen) { 718 /* 719 * At end of cluster, write it out if seqcount tells us we 720 * are operating sequentially, otherwise let the buf or 721 * update daemon handle it. 722 */ 723 bdwrite(bp); 724 if (seqcount > 1) 725 cluster_wbuild_wb(vp, lblocksize, vp->v_cstart, vp->v_clen + 1); 726 vp->v_clen = 0; 727 vp->v_cstart = lbn + 1; 728 } else if (vm_page_count_severe()) { 729 /* 730 * We are low on memory, get it going NOW 731 */ 732 bawrite(bp); 733 } else { 734 /* 735 * In the middle of a cluster, so just delay the I/O for now. 736 */ 737 bdwrite(bp); 738 } 739 vp->v_lastw = lbn; 740 vp->v_lasta = bp->b_blkno; 741 } 742 743 744 /* 745 * This is an awful lot like cluster_rbuild...wish they could be combined. 746 * The last lbn argument is the current block on which I/O is being 747 * performed. Check to see that it doesn't fall in the middle of 748 * the current block (if last_bp == NULL). 749 */ 750 int 751 cluster_wbuild(vp, size, start_lbn, len) 752 struct vnode *vp; 753 long size; 754 daddr_t start_lbn; 755 int len; 756 { 757 struct buf *bp, *tbp; 758 int i, j, s; 759 int totalwritten = 0; 760 int dbsize = btodb(size); 761 762 GIANT_REQUIRED; 763 764 while (len > 0) { 765 s = splbio(); 766 /* 767 * If the buffer is not delayed-write (i.e. dirty), or it 768 * is delayed-write but either locked or inval, it cannot 769 * partake in the clustered write. 770 */ 771 VI_LOCK(vp); 772 if ((tbp = gbincore(&vp->v_bufobj, start_lbn)) == NULL || 773 (tbp->b_vflags & BV_BKGRDINPROG)) { 774 VI_UNLOCK(vp); 775 ++start_lbn; 776 --len; 777 splx(s); 778 continue; 779 } 780 if (BUF_LOCK(tbp, 781 LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, VI_MTX(vp))) { 782 ++start_lbn; 783 --len; 784 splx(s); 785 continue; 786 } 787 if ((tbp->b_flags & (B_INVAL | B_DELWRI)) != B_DELWRI) { 788 BUF_UNLOCK(tbp); 789 ++start_lbn; 790 --len; 791 splx(s); 792 continue; 793 } 794 bremfree(tbp); 795 tbp->b_flags &= ~B_DONE; 796 splx(s); 797 798 /* 799 * Extra memory in the buffer, punt on this buffer. 800 * XXX we could handle this in most cases, but we would 801 * have to push the extra memory down to after our max 802 * possible cluster size and then potentially pull it back 803 * up if the cluster was terminated prematurely--too much 804 * hassle. 805 */ 806 if (((tbp->b_flags & (B_CLUSTEROK | B_MALLOC | B_VMIO)) != 807 (B_CLUSTEROK | B_VMIO)) || 808 (tbp->b_bcount != tbp->b_bufsize) || 809 (tbp->b_bcount != size) || 810 (len == 1) || 811 ((bp = getpbuf(&cluster_pbuf_freecnt)) == NULL)) { 812 totalwritten += tbp->b_bufsize; 813 bawrite(tbp); 814 ++start_lbn; 815 --len; 816 continue; 817 } 818 819 /* 820 * We got a pbuf to make the cluster in. 821 * so initialise it. 822 */ 823 TAILQ_INIT(&bp->b_cluster.cluster_head); 824 bp->b_bcount = 0; 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->v_bufobj, 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_bufobj->bo_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 vm_page_lock_queues(); 942 for (j = 0; j < tbp->b_npages; j += 1) { 943 m = tbp->b_pages[j]; 944 vm_page_io_start(m); 945 vm_object_pip_add(m->object, 1); 946 if ((bp->b_npages == 0) || 947 (bp->b_pages[bp->b_npages - 1] != m)) { 948 bp->b_pages[bp->b_npages] = m; 949 bp->b_npages++; 950 } 951 } 952 vm_page_unlock_queues(); 953 VM_OBJECT_UNLOCK(tbp->b_bufobj->bo_object); 954 } 955 bp->b_bcount += size; 956 bp->b_bufsize += size; 957 958 s = splbio(); 959 bundirty(tbp); 960 tbp->b_flags &= ~B_DONE; 961 tbp->b_ioflags &= ~BIO_ERROR; 962 tbp->b_flags |= B_ASYNC; 963 tbp->b_iocmd = BIO_WRITE; 964 reassignbuf(tbp); /* put on clean list */ 965 bufobj_wref(tbp->b_bufobj); 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(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(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 1018 buflist->bs_nchildren = i + 1; 1019 return (buflist); 1020 } 1021