vfs_cluster.c revision 219699
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: head/sys/kern/vfs_cluster.c 219699 2011-03-16 16:22:59Z ivoras $"); 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) 56static int rcluster= 0; 57SYSCTL_INT(_debug, OID_AUTO, rcluster, CTLFLAG_RW, &rcluster, 0, 58 "Debug VFS clustering code"); 59#endif 60 61static MALLOC_DEFINE(M_SEGMENT, "cl_savebuf", "cluster_save buffer"); 62 63static struct cluster_save * 64 cluster_collectbufs(struct vnode *vp, struct buf *last_bp); 65static 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); 68static void cluster_callback(struct buf *); 69 70static int write_behind = 1; 71SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0, 72 "Cluster write-behind; 0: disable, 1: enable, 2: backed off"); 73 74static int read_max = 64; 75SYSCTL_INT(_vfs, OID_AUTO, read_max, CTLFLAG_RW, &read_max, 0, 76 "Cluster read-ahead max block count"); 77 78/* Page expended to mark partially backed buffers */ 79extern vm_page_t bogus_page; 80 81/* 82 * Read data to a buf, including read-ahead if we find this to be beneficial. 83 * cluster_read replaces bread. 84 */ 85int 86cluster_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 struct bufobj *bo; 98 daddr_t blkno, origblkno; 99 int maxra, racluster; 100 int error, ncontig; 101 int i; 102 103 error = 0; 104 bo = &vp->v_bufobj; 105 106 /* 107 * Try to limit the amount of read-ahead by a few 108 * ad-hoc parameters. This needs work!!! 109 */ 110 racluster = vp->v_mount->mnt_iosize_max / size; 111 maxra = seqcount; 112 maxra = min(read_max, maxra); 113 maxra = min(nbuf/8, maxra); 114 if (((u_quad_t)(lblkno + maxra + 1) * size) > filesize) 115 maxra = (filesize / size) - lblkno; 116 117 /* 118 * get the requested block 119 */ 120 *bpp = reqbp = bp = getblk(vp, lblkno, size, 0, 0, 0); 121 origblkno = lblkno; 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 bp->b_flags &= ~B_RAM; 135 BO_LOCK(bo); 136 for (i = 1; i < maxra; i++) { 137 /* 138 * Stop if the buffer does not exist or it 139 * is invalid (about to go away?) 140 */ 141 rbp = gbincore(&vp->v_bufobj, lblkno+i); 142 if (rbp == NULL || (rbp->b_flags & B_INVAL)) 143 break; 144 145 /* 146 * Set another read-ahead mark so we know 147 * to check again. (If we can lock the 148 * buffer without waiting) 149 */ 150 if ((((i % racluster) == (racluster - 1)) || 151 (i == (maxra - 1))) 152 && (0 == BUF_LOCK(rbp, 153 LK_EXCLUSIVE | LK_NOWAIT, NULL))) { 154 rbp->b_flags |= B_RAM; 155 BUF_UNLOCK(rbp); 156 } 157 } 158 BO_UNLOCK(bo); 159 if (i >= maxra) { 160 return 0; 161 } 162 lblkno += i; 163 } 164 reqbp = bp = NULL; 165 /* 166 * If it isn't in the cache, then get a chunk from 167 * disk if sequential, otherwise just get the block. 168 */ 169 } else { 170 off_t firstread = bp->b_offset; 171 int nblks; 172 173 KASSERT(bp->b_offset != NOOFFSET, 174 ("cluster_read: no buffer offset")); 175 176 ncontig = 0; 177 178 /* 179 * Compute the total number of blocks that we should read 180 * synchronously. 181 */ 182 if (firstread + totread > filesize) 183 totread = filesize - firstread; 184 nblks = howmany(totread, size); 185 if (nblks > racluster) 186 nblks = racluster; 187 188 /* 189 * Now compute the number of contiguous blocks. 190 */ 191 if (nblks > 1) { 192 error = VOP_BMAP(vp, lblkno, NULL, 193 &blkno, &ncontig, NULL); 194 /* 195 * If this failed to map just do the original block. 196 */ 197 if (error || blkno == -1) 198 ncontig = 0; 199 } 200 201 /* 202 * If we have contiguous data available do a cluster 203 * otherwise just read the requested block. 204 */ 205 if (ncontig) { 206 /* Account for our first block. */ 207 ncontig = min(ncontig + 1, nblks); 208 if (ncontig < nblks) 209 nblks = ncontig; 210 bp = cluster_rbuild(vp, filesize, lblkno, 211 blkno, size, nblks, bp); 212 lblkno += (bp->b_bufsize / size); 213 } else { 214 bp->b_flags |= B_RAM; 215 bp->b_iocmd = BIO_READ; 216 lblkno += 1; 217 } 218 } 219 220 /* 221 * handle the synchronous read so that it is available ASAP. 222 */ 223 if (bp) { 224 if ((bp->b_flags & B_CLUSTER) == 0) { 225 vfs_busy_pages(bp, 0); 226 } 227 bp->b_flags &= ~B_INVAL; 228 bp->b_ioflags &= ~BIO_ERROR; 229 if ((bp->b_flags & B_ASYNC) || bp->b_iodone != NULL) 230 BUF_KERNPROC(bp); 231 bp->b_iooffset = dbtob(bp->b_blkno); 232 bstrategy(bp); 233 curthread->td_ru.ru_inblock++; 234 } 235 236 /* 237 * If we have been doing sequential I/O, then do some read-ahead. 238 */ 239 while (lblkno < (origblkno + maxra)) { 240 error = VOP_BMAP(vp, lblkno, NULL, &blkno, &ncontig, NULL); 241 if (error) 242 break; 243 244 if (blkno == -1) 245 break; 246 247 /* 248 * We could throttle ncontig here by maxra but we might as 249 * well read the data if it is contiguous. We're throttled 250 * by racluster anyway. 251 */ 252 if (ncontig) { 253 ncontig = min(ncontig + 1, racluster); 254 rbp = cluster_rbuild(vp, filesize, lblkno, blkno, 255 size, ncontig, NULL); 256 lblkno += (rbp->b_bufsize / size); 257 if (rbp->b_flags & B_DELWRI) { 258 bqrelse(rbp); 259 continue; 260 } 261 } else { 262 rbp = getblk(vp, lblkno, size, 0, 0, 0); 263 lblkno += 1; 264 if (rbp->b_flags & B_DELWRI) { 265 bqrelse(rbp); 266 continue; 267 } 268 rbp->b_flags |= B_ASYNC | B_RAM; 269 rbp->b_iocmd = BIO_READ; 270 rbp->b_blkno = blkno; 271 } 272 if (rbp->b_flags & B_CACHE) { 273 rbp->b_flags &= ~B_ASYNC; 274 bqrelse(rbp); 275 continue; 276 } 277 if ((rbp->b_flags & B_CLUSTER) == 0) { 278 vfs_busy_pages(rbp, 0); 279 } 280 rbp->b_flags &= ~B_INVAL; 281 rbp->b_ioflags &= ~BIO_ERROR; 282 if ((rbp->b_flags & B_ASYNC) || rbp->b_iodone != NULL) 283 BUF_KERNPROC(rbp); 284 rbp->b_iooffset = dbtob(rbp->b_blkno); 285 bstrategy(rbp); 286 curthread->td_ru.ru_inblock++; 287 } 288 289 if (reqbp) 290 return (bufwait(reqbp)); 291 else 292 return (error); 293} 294 295/* 296 * If blocks are contiguous on disk, use this to provide clustered 297 * read ahead. We will read as many blocks as possible sequentially 298 * and then parcel them up into logical blocks in the buffer hash table. 299 */ 300static struct buf * 301cluster_rbuild(vp, filesize, lbn, blkno, size, run, fbp) 302 struct vnode *vp; 303 u_quad_t filesize; 304 daddr_t lbn; 305 daddr_t blkno; 306 long size; 307 int run; 308 struct buf *fbp; 309{ 310 struct bufobj *bo; 311 struct buf *bp, *tbp; 312 daddr_t bn; 313 off_t off; 314 long tinc, tsize; 315 int i, inc, j, toff; 316 317 KASSERT(size == vp->v_mount->mnt_stat.f_iosize, 318 ("cluster_rbuild: size %ld != filesize %jd\n", 319 size, (intmax_t)vp->v_mount->mnt_stat.f_iosize)); 320 321 /* 322 * avoid a division 323 */ 324 while ((u_quad_t) size * (lbn + run) > filesize) { 325 --run; 326 } 327 328 if (fbp) { 329 tbp = fbp; 330 tbp->b_iocmd = BIO_READ; 331 } else { 332 tbp = getblk(vp, lbn, size, 0, 0, 0); 333 if (tbp->b_flags & B_CACHE) 334 return tbp; 335 tbp->b_flags |= B_ASYNC | B_RAM; 336 tbp->b_iocmd = BIO_READ; 337 } 338 tbp->b_blkno = blkno; 339 if( (tbp->b_flags & B_MALLOC) || 340 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1) ) 341 return tbp; 342 343 bp = trypbuf(&cluster_pbuf_freecnt); 344 if (bp == 0) 345 return tbp; 346 347 /* 348 * We are synthesizing a buffer out of vm_page_t's, but 349 * if the block size is not page aligned then the starting 350 * address may not be either. Inherit the b_data offset 351 * from the original buffer. 352 */ 353 bp->b_data = (char *)((vm_offset_t)bp->b_data | 354 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 355 bp->b_flags = B_ASYNC | B_CLUSTER | B_VMIO; 356 bp->b_iocmd = BIO_READ; 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 bo = &vp->v_bufobj; 372 for (bn = blkno, i = 0; i < run; ++i, bn += inc) { 373 if (i != 0) { 374 if ((bp->b_npages * PAGE_SIZE) + 375 round_page(size) > vp->v_mount->mnt_iosize_max) { 376 break; 377 } 378 379 tbp = getblk(vp, lbn + i, size, 0, 0, GB_LOCK_NOWAIT); 380 381 /* Don't wait around for locked bufs. */ 382 if (tbp == NULL) 383 break; 384 385 /* 386 * Stop scanning if the buffer is fully valid 387 * (marked B_CACHE), or locked (may be doing a 388 * background write), or if the buffer is not 389 * VMIO backed. The clustering code can only deal 390 * with VMIO-backed buffers. 391 */ 392 BO_LOCK(bo); 393 if ((tbp->b_vflags & BV_BKGRDINPROG) || 394 (tbp->b_flags & B_CACHE) || 395 (tbp->b_flags & B_VMIO) == 0) { 396 BO_UNLOCK(bo); 397 bqrelse(tbp); 398 break; 399 } 400 BO_UNLOCK(bo); 401 402 /* 403 * The buffer must be completely invalid in order to 404 * take part in the cluster. If it is partially valid 405 * then we stop. 406 */ 407 off = tbp->b_offset; 408 tsize = size; 409 VM_OBJECT_LOCK(tbp->b_bufobj->bo_object); 410 for (j = 0; tsize > 0; j++) { 411 toff = off & PAGE_MASK; 412 tinc = tsize; 413 if (toff + tinc > PAGE_SIZE) 414 tinc = PAGE_SIZE - toff; 415 VM_OBJECT_LOCK_ASSERT(tbp->b_pages[j]->object, 416 MA_OWNED); 417 if ((tbp->b_pages[j]->valid & 418 vm_page_bits(toff, tinc)) != 0) 419 break; 420 off += tinc; 421 tsize -= tinc; 422 } 423 VM_OBJECT_UNLOCK(tbp->b_bufobj->bo_object); 424 if (tsize > 0) { 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_ASYNC; 443 tbp->b_iocmd = BIO_READ; 444 if (tbp->b_blkno == tbp->b_lblkno) { 445 tbp->b_blkno = bn; 446 } else if (tbp->b_blkno != bn) { 447 brelse(tbp); 448 break; 449 } 450 } 451 /* 452 * XXX fbp from caller may not be B_ASYNC, but we are going 453 * to biodone() it in cluster_callback() anyway 454 */ 455 BUF_KERNPROC(tbp); 456 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head, 457 tbp, b_cluster.cluster_entry); 458 VM_OBJECT_LOCK(tbp->b_bufobj->bo_object); 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) 470 tbp->b_pages[j] = bogus_page; 471 } 472 VM_OBJECT_UNLOCK(tbp->b_bufobj->bo_object); 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 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 491 for (j = 0; j < bp->b_npages; j++) { 492 VM_OBJECT_LOCK_ASSERT(bp->b_pages[j]->object, MA_OWNED); 493 if (bp->b_pages[j]->valid == VM_PAGE_BITS_ALL) 494 bp->b_pages[j] = bogus_page; 495 } 496 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 497 if (bp->b_bufsize > bp->b_kvasize) 498 panic("cluster_rbuild: b_bufsize(%ld) > b_kvasize(%d)\n", 499 bp->b_bufsize, bp->b_kvasize); 500 bp->b_kvasize = bp->b_bufsize; 501 502 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 503 (vm_page_t *)bp->b_pages, bp->b_npages); 504 return (bp); 505} 506 507/* 508 * Cleanup after a clustered read or write. 509 * This is complicated by the fact that any of the buffers might have 510 * extra memory (if there were no empty buffer headers at allocbuf time) 511 * that we will need to shift around. 512 */ 513static void 514cluster_callback(bp) 515 struct buf *bp; 516{ 517 struct buf *nbp, *tbp; 518 int error = 0; 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 pbrelvp(bp); 554 relpbuf(bp, &cluster_pbuf_freecnt); 555} 556 557/* 558 * cluster_wbuild_wb: 559 * 560 * Implement modified write build for cluster. 561 * 562 * write_behind = 0 write behind disabled 563 * write_behind = 1 write behind normal (default) 564 * write_behind = 2 write behind backed-off 565 */ 566 567static __inline int 568cluster_wbuild_wb(struct vnode *vp, long size, daddr_t start_lbn, int len) 569{ 570 int r = 0; 571 572 switch(write_behind) { 573 case 2: 574 if (start_lbn < len) 575 break; 576 start_lbn -= len; 577 /* FALLTHROUGH */ 578 case 1: 579 r = cluster_wbuild(vp, size, start_lbn, len); 580 /* FALLTHROUGH */ 581 default: 582 /* FALLTHROUGH */ 583 break; 584 } 585 return(r); 586} 587 588/* 589 * Do clustered write for FFS. 590 * 591 * Three cases: 592 * 1. Write is not sequential (write asynchronously) 593 * Write is sequential: 594 * 2. beginning of cluster - begin cluster 595 * 3. middle of a cluster - add to cluster 596 * 4. end of a cluster - asynchronously write cluster 597 */ 598void 599cluster_write(struct vnode *vp, struct buf *bp, u_quad_t filesize, int seqcount) 600{ 601 daddr_t lbn; 602 int maxclen, cursize; 603 int lblocksize; 604 int async; 605 606 if (vp->v_type == VREG) { 607 async = vp->v_mount->mnt_kern_flag & MNTK_ASYNC; 608 lblocksize = vp->v_mount->mnt_stat.f_iosize; 609 } else { 610 async = 0; 611 lblocksize = bp->b_bufsize; 612 } 613 lbn = bp->b_lblkno; 614 KASSERT(bp->b_offset != NOOFFSET, ("cluster_write: no buffer offset")); 615 616 /* Initialize vnode to beginning of file. */ 617 if (lbn == 0) 618 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0; 619 620 if (vp->v_clen == 0 || lbn != vp->v_lastw + 1 || 621 (bp->b_blkno != vp->v_lasta + btodb(lblocksize))) { 622 maxclen = vp->v_mount->mnt_iosize_max / lblocksize - 1; 623 if (vp->v_clen != 0) { 624 /* 625 * Next block is not sequential. 626 * 627 * If we are not writing at end of file, the process 628 * seeked to another point in the file since its last 629 * write, or we have reached our maximum cluster size, 630 * then push the previous cluster. Otherwise try 631 * reallocating to make it sequential. 632 * 633 * Change to algorithm: only push previous cluster if 634 * it was sequential from the point of view of the 635 * seqcount heuristic, otherwise leave the buffer 636 * intact so we can potentially optimize the I/O 637 * later on in the buf_daemon or update daemon 638 * flush. 639 */ 640 cursize = vp->v_lastw - vp->v_cstart + 1; 641 if (((u_quad_t) bp->b_offset + lblocksize) != filesize || 642 lbn != vp->v_lastw + 1 || vp->v_clen <= cursize) { 643 if (!async && seqcount > 0) { 644 cluster_wbuild_wb(vp, lblocksize, 645 vp->v_cstart, cursize); 646 } 647 } else { 648 struct buf **bpp, **endbp; 649 struct cluster_save *buflist; 650 651 buflist = cluster_collectbufs(vp, bp); 652 endbp = &buflist->bs_children 653 [buflist->bs_nchildren - 1]; 654 if (VOP_REALLOCBLKS(vp, buflist)) { 655 /* 656 * Failed, push the previous cluster 657 * if *really* writing sequentially 658 * in the logical file (seqcount > 1), 659 * otherwise delay it in the hopes that 660 * the low level disk driver can 661 * optimize the write ordering. 662 */ 663 for (bpp = buflist->bs_children; 664 bpp < endbp; bpp++) 665 brelse(*bpp); 666 free(buflist, M_SEGMENT); 667 if (seqcount > 1) { 668 cluster_wbuild_wb(vp, 669 lblocksize, vp->v_cstart, 670 cursize); 671 } 672 } else { 673 /* 674 * Succeeded, keep building cluster. 675 */ 676 for (bpp = buflist->bs_children; 677 bpp <= endbp; bpp++) 678 bdwrite(*bpp); 679 free(buflist, M_SEGMENT); 680 vp->v_lastw = lbn; 681 vp->v_lasta = bp->b_blkno; 682 return; 683 } 684 } 685 } 686 /* 687 * Consider beginning a cluster. If at end of file, make 688 * cluster as large as possible, otherwise find size of 689 * existing cluster. 690 */ 691 if ((vp->v_type == VREG) && 692 ((u_quad_t) bp->b_offset + lblocksize) != filesize && 693 (bp->b_blkno == bp->b_lblkno) && 694 (VOP_BMAP(vp, lbn, NULL, &bp->b_blkno, &maxclen, NULL) || 695 bp->b_blkno == -1)) { 696 bawrite(bp); 697 vp->v_clen = 0; 698 vp->v_lasta = bp->b_blkno; 699 vp->v_cstart = lbn + 1; 700 vp->v_lastw = lbn; 701 return; 702 } 703 vp->v_clen = maxclen; 704 if (!async && maxclen == 0) { /* I/O not contiguous */ 705 vp->v_cstart = lbn + 1; 706 bawrite(bp); 707 } else { /* Wait for rest of cluster */ 708 vp->v_cstart = lbn; 709 bdwrite(bp); 710 } 711 } else if (lbn == vp->v_cstart + vp->v_clen) { 712 /* 713 * At end of cluster, write it out if seqcount tells us we 714 * are operating sequentially, otherwise let the buf or 715 * update daemon handle it. 716 */ 717 bdwrite(bp); 718 if (seqcount > 1) 719 cluster_wbuild_wb(vp, lblocksize, vp->v_cstart, vp->v_clen + 1); 720 vp->v_clen = 0; 721 vp->v_cstart = lbn + 1; 722 } else if (vm_page_count_severe()) { 723 /* 724 * We are low on memory, get it going NOW 725 */ 726 bawrite(bp); 727 } else { 728 /* 729 * In the middle of a cluster, so just delay the I/O for now. 730 */ 731 bdwrite(bp); 732 } 733 vp->v_lastw = lbn; 734 vp->v_lasta = bp->b_blkno; 735} 736 737 738/* 739 * This is an awful lot like cluster_rbuild...wish they could be combined. 740 * The last lbn argument is the current block on which I/O is being 741 * performed. Check to see that it doesn't fall in the middle of 742 * the current block (if last_bp == NULL). 743 */ 744int 745cluster_wbuild(vp, size, start_lbn, len) 746 struct vnode *vp; 747 long size; 748 daddr_t start_lbn; 749 int len; 750{ 751 struct buf *bp, *tbp; 752 struct bufobj *bo; 753 int i, j; 754 int totalwritten = 0; 755 int dbsize = btodb(size); 756 757 bo = &vp->v_bufobj; 758 while (len > 0) { 759 /* 760 * If the buffer is not delayed-write (i.e. dirty), or it 761 * is delayed-write but either locked or inval, it cannot 762 * partake in the clustered write. 763 */ 764 BO_LOCK(bo); 765 if ((tbp = gbincore(&vp->v_bufobj, start_lbn)) == NULL || 766 (tbp->b_vflags & BV_BKGRDINPROG)) { 767 BO_UNLOCK(bo); 768 ++start_lbn; 769 --len; 770 continue; 771 } 772 if (BUF_LOCK(tbp, 773 LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, BO_MTX(bo))) { 774 ++start_lbn; 775 --len; 776 continue; 777 } 778 if ((tbp->b_flags & (B_INVAL | B_DELWRI)) != B_DELWRI) { 779 BUF_UNLOCK(tbp); 780 ++start_lbn; 781 --len; 782 continue; 783 } 784 if (tbp->b_pin_count > 0) { 785 BUF_UNLOCK(tbp); 786 ++start_lbn; 787 --len; 788 continue; 789 } 790 bremfree(tbp); 791 tbp->b_flags &= ~B_DONE; 792 793 /* 794 * Extra memory in the buffer, punt on this buffer. 795 * XXX we could handle this in most cases, but we would 796 * have to push the extra memory down to after our max 797 * possible cluster size and then potentially pull it back 798 * up if the cluster was terminated prematurely--too much 799 * hassle. 800 */ 801 if (((tbp->b_flags & (B_CLUSTEROK | B_MALLOC | B_VMIO)) != 802 (B_CLUSTEROK | B_VMIO)) || 803 (tbp->b_bcount != tbp->b_bufsize) || 804 (tbp->b_bcount != size) || 805 (len == 1) || 806 ((bp = getpbuf(&cluster_pbuf_freecnt)) == NULL)) { 807 totalwritten += tbp->b_bufsize; 808 bawrite(tbp); 809 ++start_lbn; 810 --len; 811 continue; 812 } 813 814 /* 815 * We got a pbuf to make the cluster in. 816 * so initialise it. 817 */ 818 TAILQ_INIT(&bp->b_cluster.cluster_head); 819 bp->b_bcount = 0; 820 bp->b_bufsize = 0; 821 bp->b_npages = 0; 822 if (tbp->b_wcred != NOCRED) 823 bp->b_wcred = crhold(tbp->b_wcred); 824 825 bp->b_blkno = tbp->b_blkno; 826 bp->b_lblkno = tbp->b_lblkno; 827 bp->b_offset = tbp->b_offset; 828 829 /* 830 * We are synthesizing a buffer out of vm_page_t's, but 831 * if the block size is not page aligned then the starting 832 * address may not be either. Inherit the b_data offset 833 * from the original buffer. 834 */ 835 bp->b_data = (char *)((vm_offset_t)bp->b_data | 836 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 837 bp->b_flags |= B_CLUSTER | 838 (tbp->b_flags & (B_VMIO | B_NEEDCOMMIT)); 839 bp->b_iodone = cluster_callback; 840 pbgetvp(vp, bp); 841 /* 842 * From this location in the file, scan forward to see 843 * if there are buffers with adjacent data that need to 844 * be written as well. 845 */ 846 for (i = 0; i < len; ++i, ++start_lbn) { 847 if (i != 0) { /* If not the first buffer */ 848 /* 849 * If the adjacent data is not even in core it 850 * can't need to be written. 851 */ 852 BO_LOCK(bo); 853 if ((tbp = gbincore(bo, start_lbn)) == NULL || 854 (tbp->b_vflags & BV_BKGRDINPROG)) { 855 BO_UNLOCK(bo); 856 break; 857 } 858 859 /* 860 * If it IS in core, but has different 861 * characteristics, or is locked (which 862 * means it could be undergoing a background 863 * I/O or be in a weird state), then don't 864 * cluster with it. 865 */ 866 if (BUF_LOCK(tbp, 867 LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, 868 BO_MTX(bo))) 869 break; 870 871 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK | 872 B_INVAL | B_DELWRI | B_NEEDCOMMIT)) 873 != (B_DELWRI | B_CLUSTEROK | 874 (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) || 875 tbp->b_wcred != bp->b_wcred) { 876 BUF_UNLOCK(tbp); 877 break; 878 } 879 880 /* 881 * Check that the combined cluster 882 * would make sense with regard to pages 883 * and would not be too large 884 */ 885 if ((tbp->b_bcount != size) || 886 ((bp->b_blkno + (dbsize * i)) != 887 tbp->b_blkno) || 888 ((tbp->b_npages + bp->b_npages) > 889 (vp->v_mount->mnt_iosize_max / PAGE_SIZE))) { 890 BUF_UNLOCK(tbp); 891 break; 892 } 893 894 /* 895 * Do not pull in pinned buffers. 896 */ 897 if (tbp->b_pin_count > 0) { 898 BUF_UNLOCK(tbp); 899 break; 900 } 901 902 /* 903 * Ok, it's passed all the tests, 904 * so remove it from the free list 905 * and mark it busy. We will use it. 906 */ 907 bremfree(tbp); 908 tbp->b_flags &= ~B_DONE; 909 } /* end of code for non-first buffers only */ 910 /* 911 * If the IO is via the VM then we do some 912 * special VM hackery (yuck). Since the buffer's 913 * block size may not be page-aligned it is possible 914 * for a page to be shared between two buffers. We 915 * have to get rid of the duplication when building 916 * the cluster. 917 */ 918 if (tbp->b_flags & B_VMIO) { 919 vm_page_t m; 920 921 VM_OBJECT_LOCK(tbp->b_bufobj->bo_object); 922 if (i != 0) { /* if not first buffer */ 923 for (j = 0; j < tbp->b_npages; j += 1) { 924 m = tbp->b_pages[j]; 925 if (m->oflags & VPO_BUSY) { 926 VM_OBJECT_UNLOCK( 927 tbp->b_object); 928 bqrelse(tbp); 929 goto finishcluster; 930 } 931 } 932 } 933 for (j = 0; j < tbp->b_npages; j += 1) { 934 m = tbp->b_pages[j]; 935 vm_page_io_start(m); 936 vm_object_pip_add(m->object, 1); 937 if ((bp->b_npages == 0) || 938 (bp->b_pages[bp->b_npages - 1] != m)) { 939 bp->b_pages[bp->b_npages] = m; 940 bp->b_npages++; 941 } 942 } 943 VM_OBJECT_UNLOCK(tbp->b_bufobj->bo_object); 944 } 945 bp->b_bcount += size; 946 bp->b_bufsize += size; 947 bundirty(tbp); 948 tbp->b_flags &= ~B_DONE; 949 tbp->b_ioflags &= ~BIO_ERROR; 950 tbp->b_flags |= B_ASYNC; 951 tbp->b_iocmd = BIO_WRITE; 952 reassignbuf(tbp); /* put on clean list */ 953 bufobj_wref(tbp->b_bufobj); 954 BUF_KERNPROC(tbp); 955 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head, 956 tbp, b_cluster.cluster_entry); 957 } 958 finishcluster: 959 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 960 (vm_page_t *) bp->b_pages, bp->b_npages); 961 if (bp->b_bufsize > bp->b_kvasize) 962 panic( 963 "cluster_wbuild: b_bufsize(%ld) > b_kvasize(%d)\n", 964 bp->b_bufsize, bp->b_kvasize); 965 bp->b_kvasize = bp->b_bufsize; 966 totalwritten += bp->b_bufsize; 967 bp->b_dirtyoff = 0; 968 bp->b_dirtyend = bp->b_bufsize; 969 bawrite(bp); 970 971 len -= i; 972 } 973 return totalwritten; 974} 975 976/* 977 * Collect together all the buffers in a cluster. 978 * Plus add one additional buffer. 979 */ 980static struct cluster_save * 981cluster_collectbufs(vp, last_bp) 982 struct vnode *vp; 983 struct buf *last_bp; 984{ 985 struct cluster_save *buflist; 986 struct buf *bp; 987 daddr_t lbn; 988 int i, len; 989 990 len = vp->v_lastw - vp->v_cstart + 1; 991 buflist = malloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist), 992 M_SEGMENT, M_WAITOK); 993 buflist->bs_nchildren = 0; 994 buflist->bs_children = (struct buf **) (buflist + 1); 995 for (lbn = vp->v_cstart, i = 0; i < len; lbn++, i++) { 996 (void) bread(vp, lbn, last_bp->b_bcount, NOCRED, &bp); 997 buflist->bs_children[i] = bp; 998 if (bp->b_blkno == bp->b_lblkno) 999 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, 1000 NULL, NULL); 1001 } 1002 buflist->bs_children[i] = bp = last_bp; 1003 if (bp->b_blkno == bp->b_lblkno) 1004 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 1005 buflist->bs_nchildren = i + 1; 1006 return (buflist); 1007} 1008