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sys/kern/vfs_cluster.c
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1 /*- 2 * Copyright (c) 1993 3 * The Regents of the University of California. All rights reserved. 4 * Modifications/enhancements: 5 * Copyright (c) 1995 John S. Dyson. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgement: 17 * This product includes software developed by the University of 18 * California, Berkeley and its contributors. 19 * 4. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 * 35 * @(#)vfs_cluster.c 8.7 (Berkeley) 2/13/94 36 * $FreeBSD: releng/5.0/sys/kern/vfs_cluster.c 106597 2002-11-07 22:41:08Z jhb $ 37 */ 38 39 #include "opt_debug_cluster.h" 40 41 #include <sys/param.h> 42 #include <sys/systm.h> 43 #include <sys/stdint.h> 44 #include <sys/kernel.h> 45 #include <sys/proc.h> 46 #include <sys/bio.h> 47 #include <sys/buf.h> 48 #include <sys/vnode.h> 49 #include <sys/malloc.h> 50 #include <sys/mount.h> 51 #include <sys/resourcevar.h> 52 #include <sys/vmmeter.h> 53 #include <vm/vm.h> 54 #include <vm/vm_object.h> 55 #include <vm/vm_page.h> 56 #include <sys/sysctl.h> 57 58 #if defined(CLUSTERDEBUG) 59 #include <sys/sysctl.h> 60 static int rcluster= 0; 61 SYSCTL_INT(_debug, OID_AUTO, rcluster, CTLFLAG_RW, &rcluster, 0, 62 "Debug VFS clustering code"); 63 #endif 64 65 static MALLOC_DEFINE(M_SEGMENT, "cluster_save buffer", "cluster_save buffer"); 66 67 static struct cluster_save * 68 cluster_collectbufs(struct vnode *vp, struct buf *last_bp); 69 static struct buf * 70 cluster_rbuild(struct vnode *vp, u_quad_t filesize, daddr_t lbn, 71 daddr_t blkno, long size, int run, struct buf *fbp); 72 73 static int write_behind = 1; 74 SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0, 75 "Cluster write-behind; 0: disable, 1: enable, 2: backed off"); 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 * Maximum number of blocks for read-ahead. 88 */ 89 #define MAXRA 32 90 91 /* 92 * Read data to a buf, including read-ahead if we find this to be beneficial. 93 * cluster_read replaces bread. 94 */ 95 int 96 cluster_read(vp, filesize, lblkno, size, cred, totread, seqcount, bpp) 97 struct vnode *vp; 98 u_quad_t filesize; 99 daddr_t lblkno; 100 long size; 101 struct ucred *cred; 102 long totread; 103 int seqcount; 104 struct buf **bpp; 105 { 106 struct buf *bp, *rbp, *reqbp; 107 daddr_t blkno, origblkno; 108 int error, num_ra; 109 int i; 110 int maxra, racluster; 111 long origtotread; 112 113 error = 0; 114 115 /* 116 * Try to limit the amount of read-ahead by a few 117 * ad-hoc parameters. This needs work!!! 118 */ 119 racluster = vp->v_mount->mnt_iosize_max / size; 120 maxra = 2 * racluster + (totread / size); 121 if (maxra > MAXRA) 122 maxra = MAXRA; 123 if (maxra > nbuf/8) 124 maxra = nbuf/8; 125 126 /* 127 * get the requested block 128 */ 129 *bpp = reqbp = bp = getblk(vp, lblkno, size, 0, 0); 130 origblkno = lblkno; 131 origtotread = totread; 132 133 /* 134 * if it is in the cache, then check to see if the reads have been 135 * sequential. If they have, then try some read-ahead, otherwise 136 * back-off on prospective read-aheads. 137 */ 138 if (bp->b_flags & B_CACHE) { 139 if (!seqcount) { 140 return 0; 141 } else if ((bp->b_flags & B_RAM) == 0) { 142 return 0; 143 } else { 144 int s; 145 struct buf *tbp; 146 bp->b_flags &= ~B_RAM; 147 /* 148 * We do the spl here so that there is no window 149 * between the incore and the b_usecount increment 150 * below. We opt to keep the spl out of the loop 151 * for efficiency. 152 */ 153 s = splbio(); 154 VI_LOCK(vp); 155 for (i = 1; i < maxra; i++) { 156 /* 157 * Stop if the buffer does not exist or it 158 * is invalid (about to go away?) 159 */ 160 tbp = gbincore(vp, lblkno+i); 161 if (tbp == NULL || (tbp->b_flags & B_INVAL)) 162 break; 163 164 /* 165 * Set another read-ahead mark so we know 166 * to check again. 167 */ 168 if (((i % racluster) == (racluster - 1)) || 169 (i == (maxra - 1))) 170 tbp->b_flags |= B_RAM; 171 } 172 VI_UNLOCK(vp); 173 splx(s); 174 if (i >= maxra) { 175 return 0; 176 } 177 lblkno += i; 178 } 179 reqbp = bp = NULL; 180 } else { 181 off_t firstread = bp->b_offset; 182 183 KASSERT(bp->b_offset != NOOFFSET, 184 ("cluster_read: no buffer offset")); 185 if (firstread + totread > filesize) 186 totread = filesize - firstread; 187 if (totread > size) { 188 int nblks = 0; 189 int ncontigafter; 190 while (totread > 0) { 191 nblks++; 192 totread -= size; 193 } 194 if (nblks == 1) 195 goto single_block_read; 196 if (nblks > racluster) 197 nblks = racluster; 198 199 error = VOP_BMAP(vp, lblkno, NULL, 200 &blkno, &ncontigafter, NULL); 201 if (error) 202 goto single_block_read; 203 if (blkno == -1) 204 goto single_block_read; 205 if (ncontigafter == 0) 206 goto single_block_read; 207 if (ncontigafter + 1 < nblks) 208 nblks = ncontigafter + 1; 209 210 bp = cluster_rbuild(vp, filesize, lblkno, 211 blkno, size, nblks, bp); 212 lblkno += (bp->b_bufsize / size); 213 } else { 214 single_block_read: 215 /* 216 * if it isn't in the cache, then get a chunk from 217 * disk if sequential, otherwise just get the block. 218 */ 219 bp->b_flags |= B_RAM; 220 bp->b_iocmd = BIO_READ; 221 lblkno += 1; 222 } 223 } 224 225 /* 226 * if we have been doing sequential I/O, then do some read-ahead 227 */ 228 rbp = NULL; 229 if (seqcount && (lblkno < (origblkno + seqcount))) { 230 /* 231 * we now build the read-ahead buffer if it is desirable. 232 */ 233 if (((u_quad_t)(lblkno + 1) * size) <= filesize && 234 !(error = VOP_BMAP(vp, lblkno, NULL, &blkno, &num_ra, NULL)) && 235 blkno != -1) { 236 int nblksread; 237 int ntoread = num_ra + 1; 238 nblksread = (origtotread + size - 1) / size; 239 if (seqcount < nblksread) 240 seqcount = nblksread; 241 if (seqcount < ntoread) 242 ntoread = seqcount; 243 if (num_ra) { 244 rbp = cluster_rbuild(vp, filesize, lblkno, 245 blkno, size, ntoread, NULL); 246 } else { 247 rbp = getblk(vp, lblkno, size, 0, 0); 248 rbp->b_flags |= B_ASYNC | B_RAM; 249 rbp->b_iocmd = BIO_READ; 250 rbp->b_blkno = blkno; 251 } 252 } 253 } 254 255 /* 256 * handle the synchronous read 257 */ 258 if (bp) { 259 #if defined(CLUSTERDEBUG) 260 if (rcluster) 261 printf("S(%ld,%ld,%d) ", 262 (long)bp->b_lblkno, bp->b_bcount, seqcount); 263 #endif 264 if ((bp->b_flags & B_CLUSTER) == 0) { 265 vfs_busy_pages(bp, 0); 266 } 267 bp->b_flags &= ~B_INVAL; 268 bp->b_ioflags &= ~BIO_ERROR; 269 if ((bp->b_flags & B_ASYNC) || bp->b_iodone != NULL) 270 BUF_KERNPROC(bp); 271 error = VOP_STRATEGY(vp, bp); 272 curproc->p_stats->p_ru.ru_inblock++; 273 } 274 275 /* 276 * and if we have read-aheads, do them too 277 */ 278 if (rbp) { 279 if (error) { 280 rbp->b_flags &= ~B_ASYNC; 281 brelse(rbp); 282 } else if (rbp->b_flags & B_CACHE) { 283 rbp->b_flags &= ~B_ASYNC; 284 bqrelse(rbp); 285 } else { 286 #if defined(CLUSTERDEBUG) 287 if (rcluster) { 288 if (bp) 289 printf("A+"); 290 else 291 printf("A"); 292 printf("(%jd,%jd,%jd,%jd) ", 293 (intmax_t)rbp->b_lblkno, 294 (intmax_t)rbp->b_bcount, 295 (intmax_t)(rbp->b_lblkno - origblkno), 296 (intmax_t)seqcount); 297 } 298 #endif 299 300 if ((rbp->b_flags & B_CLUSTER) == 0) { 301 vfs_busy_pages(rbp, 0); 302 } 303 rbp->b_flags &= ~B_INVAL; 304 rbp->b_ioflags &= ~BIO_ERROR; 305 if ((rbp->b_flags & B_ASYNC) || rbp->b_iodone != NULL) 306 BUF_KERNPROC(rbp); 307 (void) VOP_STRATEGY(vp, rbp); 308 curproc->p_stats->p_ru.ru_inblock++; 309 } 310 } 311 if (reqbp) 312 return (bufwait(reqbp)); 313 else 314 return (error); 315 } 316 317 /* 318 * If blocks are contiguous on disk, use this to provide clustered 319 * read ahead. We will read as many blocks as possible sequentially 320 * and then parcel them up into logical blocks in the buffer hash table. 321 */ 322 static struct buf * 323 cluster_rbuild(vp, filesize, lbn, blkno, size, run, fbp) 324 struct vnode *vp; 325 u_quad_t filesize; 326 daddr_t lbn; 327 daddr_t blkno; 328 long size; 329 int run; 330 struct buf *fbp; 331 { 332 struct buf *bp, *tbp; 333 daddr_t bn; 334 int i, inc, j; 335 336 GIANT_REQUIRED; 337 338 KASSERT(size == vp->v_mount->mnt_stat.f_iosize, 339 ("cluster_rbuild: size %ld != filesize %ld\n", 340 size, vp->v_mount->mnt_stat.f_iosize)); 341 342 /* 343 * avoid a division 344 */ 345 while ((u_quad_t) size * (lbn + run) > filesize) { 346 --run; 347 } 348 349 if (fbp) { 350 tbp = fbp; 351 tbp->b_iocmd = BIO_READ; 352 } else { 353 tbp = getblk(vp, lbn, size, 0, 0); 354 if (tbp->b_flags & B_CACHE) 355 return tbp; 356 tbp->b_flags |= B_ASYNC | B_RAM; 357 tbp->b_iocmd = BIO_READ; 358 } 359 360 tbp->b_blkno = blkno; 361 if( (tbp->b_flags & B_MALLOC) || 362 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1) ) 363 return tbp; 364 365 bp = trypbuf(&cluster_pbuf_freecnt); 366 if (bp == 0) 367 return tbp; 368 369 /* 370 * We are synthesizing a buffer out of vm_page_t's, but 371 * if the block size is not page aligned then the starting 372 * address may not be either. Inherit the b_data offset 373 * from the original buffer. 374 */ 375 bp->b_data = (char *)((vm_offset_t)bp->b_data | 376 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 377 bp->b_flags = B_ASYNC | B_CLUSTER | B_VMIO; 378 bp->b_iocmd = BIO_READ; 379 bp->b_iodone = cluster_callback; 380 bp->b_blkno = blkno; 381 bp->b_lblkno = lbn; 382 bp->b_offset = tbp->b_offset; 383 KASSERT(bp->b_offset != NOOFFSET, ("cluster_rbuild: no buffer offset")); 384 pbgetvp(vp, bp); 385 386 TAILQ_INIT(&bp->b_cluster.cluster_head); 387 388 bp->b_bcount = 0; 389 bp->b_bufsize = 0; 390 bp->b_npages = 0; 391 392 inc = btodb(size); 393 for (bn = blkno, i = 0; i < run; ++i, bn += inc) { 394 if (i != 0) { 395 if ((bp->b_npages * PAGE_SIZE) + 396 round_page(size) > vp->v_mount->mnt_iosize_max) { 397 break; 398 } 399 400 /* 401 * Shortcut some checks and try to avoid buffers that 402 * would block in the lock. The same checks have to 403 * be made again after we officially get the buffer. 404 */ 405 if ((tbp = incore(vp, lbn + i)) != NULL && 406 (tbp->b_flags & B_INVAL) == 0) { 407 if (BUF_LOCK(tbp, LK_EXCLUSIVE | LK_NOWAIT)) 408 break; 409 BUF_UNLOCK(tbp); 410 411 for (j = 0; j < tbp->b_npages; j++) { 412 if (tbp->b_pages[j]->valid) 413 break; 414 } 415 416 if (j != tbp->b_npages) 417 break; 418 419 if (tbp->b_bcount != size) 420 break; 421 } 422 423 tbp = getblk(vp, lbn + i, size, 0, 0); 424 425 /* 426 * Stop scanning if the buffer is fully valid 427 * (marked B_CACHE), or locked (may be doing a 428 * background write), or if the buffer is not 429 * VMIO backed. The clustering code can only deal 430 * with VMIO-backed buffers. 431 */ 432 if ((tbp->b_flags & (B_CACHE|B_LOCKED)) || 433 (tbp->b_flags & B_VMIO) == 0) { 434 bqrelse(tbp); 435 break; 436 } 437 438 /* 439 * The buffer must be completely invalid in order to 440 * take part in the cluster. If it is partially valid 441 * then we stop. 442 */ 443 for (j = 0;j < tbp->b_npages; j++) { 444 if (tbp->b_pages[j]->valid) 445 break; 446 } 447 if (j != tbp->b_npages) { 448 bqrelse(tbp); 449 break; 450 } 451 452 /* 453 * Set a read-ahead mark as appropriate 454 */ 455 if ((fbp && (i == 1)) || (i == (run - 1))) 456 tbp->b_flags |= B_RAM; 457 458 /* 459 * Set the buffer up for an async read (XXX should 460 * we do this only if we do not wind up brelse()ing?). 461 * Set the block number if it isn't set, otherwise 462 * if it is make sure it matches the block number we 463 * expect. 464 */ 465 tbp->b_flags |= B_ASYNC; 466 tbp->b_iocmd = BIO_READ; 467 if (tbp->b_blkno == tbp->b_lblkno) { 468 tbp->b_blkno = bn; 469 } else if (tbp->b_blkno != bn) { 470 brelse(tbp); 471 break; 472 } 473 } 474 /* 475 * XXX fbp from caller may not be B_ASYNC, but we are going 476 * to biodone() it in cluster_callback() anyway 477 */ 478 BUF_KERNPROC(tbp); 479 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head, 480 tbp, b_cluster.cluster_entry); 481 vm_page_lock_queues(); 482 for (j = 0; j < tbp->b_npages; j += 1) { 483 vm_page_t m; 484 m = tbp->b_pages[j]; 485 vm_page_io_start(m); 486 vm_object_pip_add(m->object, 1); 487 if ((bp->b_npages == 0) || 488 (bp->b_pages[bp->b_npages-1] != m)) { 489 bp->b_pages[bp->b_npages] = m; 490 bp->b_npages++; 491 } 492 if ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) 493 tbp->b_pages[j] = bogus_page; 494 } 495 vm_page_unlock_queues(); 496 /* 497 * XXX shouldn't this be += size for both, like in 498 * cluster_wbuild()? 499 * 500 * Don't inherit tbp->b_bufsize as it may be larger due to 501 * a non-page-aligned size. Instead just aggregate using 502 * 'size'. 503 */ 504 if (tbp->b_bcount != size) 505 printf("warning: tbp->b_bcount wrong %ld vs %ld\n", tbp->b_bcount, size); 506 if (tbp->b_bufsize != size) 507 printf("warning: tbp->b_bufsize wrong %ld vs %ld\n", tbp->b_bufsize, size); 508 bp->b_bcount += size; 509 bp->b_bufsize += size; 510 } 511 512 /* 513 * Fully valid pages in the cluster are already good and do not need 514 * to be re-read from disk. Replace the page with bogus_page 515 */ 516 for (j = 0; j < bp->b_npages; j++) { 517 if ((bp->b_pages[j]->valid & VM_PAGE_BITS_ALL) == 518 VM_PAGE_BITS_ALL) { 519 bp->b_pages[j] = bogus_page; 520 } 521 } 522 if (bp->b_bufsize > bp->b_kvasize) 523 panic("cluster_rbuild: b_bufsize(%ld) > b_kvasize(%d)\n", 524 bp->b_bufsize, bp->b_kvasize); 525 bp->b_kvasize = bp->b_bufsize; 526 527 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 528 (vm_page_t *)bp->b_pages, bp->b_npages); 529 return (bp); 530 } 531 532 /* 533 * Cleanup after a clustered read or write. 534 * This is complicated by the fact that any of the buffers might have 535 * extra memory (if there were no empty buffer headers at allocbuf time) 536 * that we will need to shift around. 537 */ 538 void 539 cluster_callback(bp) 540 struct buf *bp; 541 { 542 struct buf *nbp, *tbp; 543 int error = 0; 544 545 GIANT_REQUIRED; 546 547 /* 548 * Must propogate errors to all the components. 549 */ 550 if (bp->b_ioflags & BIO_ERROR) 551 error = bp->b_error; 552 553 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages); 554 /* 555 * Move memory from the large cluster buffer into the component 556 * buffers and mark IO as done on these. 557 */ 558 for (tbp = TAILQ_FIRST(&bp->b_cluster.cluster_head); 559 tbp; tbp = nbp) { 560 nbp = TAILQ_NEXT(&tbp->b_cluster, cluster_entry); 561 if (error) { 562 tbp->b_ioflags |= BIO_ERROR; 563 tbp->b_error = error; 564 } else { 565 tbp->b_dirtyoff = tbp->b_dirtyend = 0; 566 tbp->b_flags &= ~B_INVAL; 567 tbp->b_ioflags &= ~BIO_ERROR; 568 /* 569 * XXX the bdwrite()/bqrelse() issued during 570 * cluster building clears B_RELBUF (see bqrelse() 571 * comment). If direct I/O was specified, we have 572 * to restore it here to allow the buffer and VM 573 * to be freed. 574 */ 575 if (tbp->b_flags & B_DIRECT) 576 tbp->b_flags |= B_RELBUF; 577 } 578 bufdone(tbp); 579 } 580 relpbuf(bp, &cluster_pbuf_freecnt); 581 } 582 583 /* 584 * cluster_wbuild_wb: 585 * 586 * Implement modified write build for cluster. 587 * 588 * write_behind = 0 write behind disabled 589 * write_behind = 1 write behind normal (default) 590 * write_behind = 2 write behind backed-off 591 */ 592 593 static __inline int 594 cluster_wbuild_wb(struct vnode *vp, long size, daddr_t start_lbn, int len) 595 { 596 int r = 0; 597 598 switch(write_behind) { 599 case 2: 600 if (start_lbn < len) 601 break; 602 start_lbn -= len; 603 /* FALLTHROUGH */ 604 case 1: 605 r = cluster_wbuild(vp, size, start_lbn, len); 606 /* FALLTHROUGH */ 607 default: 608 /* FALLTHROUGH */ 609 break; 610 } 611 return(r); 612 } 613 614 /* 615 * Do clustered write for FFS. 616 * 617 * Three cases: 618 * 1. Write is not sequential (write asynchronously) 619 * Write is sequential: 620 * 2. beginning of cluster - begin cluster 621 * 3. middle of a cluster - add to cluster 622 * 4. end of a cluster - asynchronously write cluster 623 */ 624 void 625 cluster_write(bp, filesize, seqcount) 626 struct buf *bp; 627 u_quad_t filesize; 628 int seqcount; 629 { 630 struct vnode *vp; 631 daddr_t lbn; 632 int maxclen, cursize; 633 int lblocksize; 634 int async; 635 636 vp = bp->b_vp; 637 if (vp->v_type == VREG) { 638 async = vp->v_mount->mnt_flag & MNT_ASYNC; 639 lblocksize = vp->v_mount->mnt_stat.f_iosize; 640 } else { 641 async = 0; 642 lblocksize = bp->b_bufsize; 643 } 644 lbn = bp->b_lblkno; 645 KASSERT(bp->b_offset != NOOFFSET, ("cluster_write: no buffer offset")); 646 647 /* Initialize vnode to beginning of file. */ 648 if (lbn == 0) 649 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0; 650 651 if (vp->v_clen == 0 || lbn != vp->v_lastw + 1 || 652 (bp->b_blkno != vp->v_lasta + btodb(lblocksize))) { 653 maxclen = vp->v_mount->mnt_iosize_max / lblocksize - 1; 654 if (vp->v_clen != 0) { 655 /* 656 * Next block is not sequential. 657 * 658 * If we are not writing at end of file, the process 659 * seeked to another point in the file since its last 660 * write, or we have reached our maximum cluster size, 661 * then push the previous cluster. Otherwise try 662 * reallocating to make it sequential. 663 * 664 * Change to algorithm: only push previous cluster if 665 * it was sequential from the point of view of the 666 * seqcount heuristic, otherwise leave the buffer 667 * intact so we can potentially optimize the I/O 668 * later on in the buf_daemon or update daemon 669 * flush. 670 */ 671 cursize = vp->v_lastw - vp->v_cstart + 1; 672 if (((u_quad_t) bp->b_offset + lblocksize) != filesize || 673 lbn != vp->v_lastw + 1 || vp->v_clen <= cursize) { 674 if (!async && seqcount > 0) { 675 cluster_wbuild_wb(vp, lblocksize, 676 vp->v_cstart, cursize); 677 } 678 } else { 679 struct buf **bpp, **endbp; 680 struct cluster_save *buflist; 681 682 buflist = cluster_collectbufs(vp, bp); 683 endbp = &buflist->bs_children 684 [buflist->bs_nchildren - 1]; 685 if (VOP_REALLOCBLKS(vp, buflist)) { 686 /* 687 * Failed, push the previous cluster 688 * if *really* writing sequentially 689 * in the logical file (seqcount > 1), 690 * otherwise delay it in the hopes that 691 * the low level disk driver can 692 * optimize the write ordering. 693 */ 694 for (bpp = buflist->bs_children; 695 bpp < endbp; bpp++) 696 brelse(*bpp); 697 free(buflist, M_SEGMENT); 698 if (seqcount > 1) { 699 cluster_wbuild_wb(vp, 700 lblocksize, vp->v_cstart, 701 cursize); 702 } 703 } else { 704 /* 705 * Succeeded, keep building cluster. 706 */ 707 for (bpp = buflist->bs_children; 708 bpp <= endbp; bpp++) 709 bdwrite(*bpp); 710 free(buflist, M_SEGMENT); 711 vp->v_lastw = lbn; 712 vp->v_lasta = bp->b_blkno; 713 return; 714 } 715 } 716 } 717 /* 718 * Consider beginning a cluster. If at end of file, make 719 * cluster as large as possible, otherwise find size of 720 * existing cluster. 721 */ 722 if ((vp->v_type == VREG) && 723 ((u_quad_t) bp->b_offset + lblocksize) != filesize && 724 (bp->b_blkno == bp->b_lblkno) && 725 (VOP_BMAP(vp, lbn, NULL, &bp->b_blkno, &maxclen, NULL) || 726 bp->b_blkno == -1)) { 727 bawrite(bp); 728 vp->v_clen = 0; 729 vp->v_lasta = bp->b_blkno; 730 vp->v_cstart = lbn + 1; 731 vp->v_lastw = lbn; 732 return; 733 } 734 vp->v_clen = maxclen; 735 if (!async && maxclen == 0) { /* I/O not contiguous */ 736 vp->v_cstart = lbn + 1; 737 bawrite(bp); 738 } else { /* Wait for rest of cluster */ 739 vp->v_cstart = lbn; 740 bdwrite(bp); 741 } 742 } else if (lbn == vp->v_cstart + vp->v_clen) { 743 /* 744 * At end of cluster, write it out if seqcount tells us we 745 * are operating sequentially, otherwise let the buf or 746 * update daemon handle it. 747 */ 748 bdwrite(bp); 749 if (seqcount > 1) 750 cluster_wbuild_wb(vp, lblocksize, vp->v_cstart, vp->v_clen + 1); 751 vp->v_clen = 0; 752 vp->v_cstart = lbn + 1; 753 } else if (vm_page_count_severe()) { 754 /* 755 * We are low on memory, get it going NOW 756 */ 757 bawrite(bp); 758 } else { 759 /* 760 * In the middle of a cluster, so just delay the I/O for now. 761 */ 762 bdwrite(bp); 763 } 764 vp->v_lastw = lbn; 765 vp->v_lasta = bp->b_blkno; 766 } 767 768 769 /* 770 * This is an awful lot like cluster_rbuild...wish they could be combined. 771 * The last lbn argument is the current block on which I/O is being 772 * performed. Check to see that it doesn't fall in the middle of 773 * the current block (if last_bp == NULL). 774 */ 775 int 776 cluster_wbuild(vp, size, start_lbn, len) 777 struct vnode *vp; 778 long size; 779 daddr_t start_lbn; 780 int len; 781 { 782 struct buf *bp, *tbp; 783 int i, j, s; 784 int totalwritten = 0; 785 int dbsize = btodb(size); 786 787 GIANT_REQUIRED; 788 789 while (len > 0) { 790 s = splbio(); 791 /* 792 * If the buffer is not delayed-write (i.e. dirty), or it 793 * is delayed-write but either locked or inval, it cannot 794 * partake in the clustered write. 795 */ 796 if (((tbp = incore(vp, start_lbn)) == NULL) || 797 ((tbp->b_flags & (B_LOCKED | B_INVAL | B_DELWRI)) != B_DELWRI) || 798 BUF_LOCK(tbp, LK_EXCLUSIVE | LK_NOWAIT)) { 799 ++start_lbn; 800 --len; 801 splx(s); 802 continue; 803 } 804 bremfree(tbp); 805 tbp->b_flags &= ~B_DONE; 806 splx(s); 807 808 /* 809 * Extra memory in the buffer, punt on this buffer. 810 * XXX we could handle this in most cases, but we would 811 * have to push the extra memory down to after our max 812 * possible cluster size and then potentially pull it back 813 * up if the cluster was terminated prematurely--too much 814 * hassle. 815 */ 816 if (((tbp->b_flags & (B_CLUSTEROK | B_MALLOC | B_VMIO)) != 817 (B_CLUSTEROK | B_VMIO)) || 818 (tbp->b_bcount != tbp->b_bufsize) || 819 (tbp->b_bcount != size) || 820 (len == 1) || 821 ((bp = getpbuf(&cluster_pbuf_freecnt)) == NULL)) { 822 totalwritten += tbp->b_bufsize; 823 bawrite(tbp); 824 ++start_lbn; 825 --len; 826 continue; 827 } 828 829 /* 830 * We got a pbuf to make the cluster in. 831 * so initialise it. 832 */ 833 TAILQ_INIT(&bp->b_cluster.cluster_head); 834 bp->b_bcount = 0; 835 bp->b_magic = tbp->b_magic; 836 bp->b_op = tbp->b_op; 837 bp->b_bufsize = 0; 838 bp->b_npages = 0; 839 if (tbp->b_wcred != NOCRED) 840 bp->b_wcred = crhold(tbp->b_wcred); 841 842 bp->b_blkno = tbp->b_blkno; 843 bp->b_lblkno = tbp->b_lblkno; 844 bp->b_offset = tbp->b_offset; 845 846 /* 847 * We are synthesizing a buffer out of vm_page_t's, but 848 * if the block size is not page aligned then the starting 849 * address may not be either. Inherit the b_data offset 850 * from the original buffer. 851 */ 852 bp->b_data = (char *)((vm_offset_t)bp->b_data | 853 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 854 bp->b_flags |= B_CLUSTER | 855 (tbp->b_flags & (B_VMIO | B_NEEDCOMMIT | B_NOWDRAIN)); 856 bp->b_iodone = cluster_callback; 857 pbgetvp(vp, bp); 858 /* 859 * From this location in the file, scan forward to see 860 * if there are buffers with adjacent data that need to 861 * be written as well. 862 */ 863 for (i = 0; i < len; ++i, ++start_lbn) { 864 if (i != 0) { /* If not the first buffer */ 865 s = splbio(); 866 /* 867 * If the adjacent data is not even in core it 868 * can't need to be written. 869 */ 870 if ((tbp = incore(vp, start_lbn)) == NULL) { 871 splx(s); 872 break; 873 } 874 875 /* 876 * If it IS in core, but has different 877 * characteristics, or is locked (which 878 * means it could be undergoing a background 879 * I/O or be in a weird state), then don't 880 * cluster with it. 881 */ 882 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK | 883 B_INVAL | B_DELWRI | B_NEEDCOMMIT)) 884 != (B_DELWRI | B_CLUSTEROK | 885 (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) || 886 (tbp->b_flags & B_LOCKED) || 887 tbp->b_wcred != bp->b_wcred || 888 BUF_LOCK(tbp, LK_EXCLUSIVE | LK_NOWAIT)) { 889 splx(s); 890 break; 891 } 892 893 /* 894 * Check that the combined cluster 895 * would make sense with regard to pages 896 * and would not be too large 897 */ 898 if ((tbp->b_bcount != size) || 899 ((bp->b_blkno + (dbsize * i)) != 900 tbp->b_blkno) || 901 ((tbp->b_npages + bp->b_npages) > 902 (vp->v_mount->mnt_iosize_max / PAGE_SIZE))) { 903 BUF_UNLOCK(tbp); 904 splx(s); 905 break; 906 } 907 /* 908 * Ok, it's passed all the tests, 909 * so remove it from the free list 910 * and mark it busy. We will use it. 911 */ 912 bremfree(tbp); 913 tbp->b_flags &= ~B_DONE; 914 splx(s); 915 } /* end of code for non-first buffers only */ 916 /* check for latent dependencies to be handled */ 917 if ((LIST_FIRST(&tbp->b_dep)) != NULL) 918 buf_start(tbp); 919 /* 920 * If the IO is via the VM then we do some 921 * special VM hackery (yuck). Since the buffer's 922 * block size may not be page-aligned it is possible 923 * for a page to be shared between two buffers. We 924 * have to get rid of the duplication when building 925 * the cluster. 926 */ 927 if (tbp->b_flags & B_VMIO) { 928 vm_page_t m; 929 930 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 bqrelse(tbp); 935 goto finishcluster; 936 } 937 } 938 } 939 vm_page_lock_queues(); 940 for (j = 0; j < tbp->b_npages; j += 1) { 941 m = tbp->b_pages[j]; 942 vm_page_io_start(m); 943 vm_object_pip_add(m->object, 1); 944 if ((bp->b_npages == 0) || 945 (bp->b_pages[bp->b_npages - 1] != m)) { 946 bp->b_pages[bp->b_npages] = m; 947 bp->b_npages++; 948 } 949 } 950 vm_page_unlock_queues(); 951 } 952 bp->b_bcount += size; 953 bp->b_bufsize += size; 954 955 s = splbio(); 956 bundirty(tbp); 957 tbp->b_flags &= ~B_DONE; 958 tbp->b_ioflags &= ~BIO_ERROR; 959 tbp->b_flags |= B_ASYNC; 960 tbp->b_iocmd = BIO_WRITE; 961 reassignbuf(tbp, tbp->b_vp); /* put on clean list */ 962 VI_LOCK(tbp->b_vp); 963 ++tbp->b_vp->v_numoutput; 964 VI_UNLOCK(tbp->b_vp); 965 splx(s); 966 BUF_KERNPROC(tbp); 967 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head, 968 tbp, b_cluster.cluster_entry); 969 } 970 finishcluster: 971 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 972 (vm_page_t *) bp->b_pages, bp->b_npages); 973 if (bp->b_bufsize > bp->b_kvasize) 974 panic( 975 "cluster_wbuild: b_bufsize(%ld) > b_kvasize(%d)\n", 976 bp->b_bufsize, bp->b_kvasize); 977 bp->b_kvasize = bp->b_bufsize; 978 totalwritten += bp->b_bufsize; 979 bp->b_dirtyoff = 0; 980 bp->b_dirtyend = bp->b_bufsize; 981 bawrite(bp); 982 983 len -= i; 984 } 985 return totalwritten; 986 } 987 988 /* 989 * Collect together all the buffers in a cluster. 990 * Plus add one additional buffer. 991 */ 992 static struct cluster_save * 993 cluster_collectbufs(vp, last_bp) 994 struct vnode *vp; 995 struct buf *last_bp; 996 { 997 struct cluster_save *buflist; 998 struct buf *bp; 999 daddr_t lbn; 1000 int i, len; 1001 1002 len = vp->v_lastw - vp->v_cstart + 1; 1003 buflist = malloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist), 1004 M_SEGMENT, M_WAITOK); 1005 buflist->bs_nchildren = 0; 1006 buflist->bs_children = (struct buf **) (buflist + 1); 1007 for (lbn = vp->v_cstart, i = 0; i < len; lbn++, i++) { 1008 (void) bread(vp, lbn, last_bp->b_bcount, NOCRED, &bp); 1009 buflist->bs_children[i] = bp; 1010 if (bp->b_blkno == bp->b_lblkno) 1011 VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno, 1012 NULL, NULL); 1013 } 1014 buflist->bs_children[i] = bp = last_bp; 1015 if (bp->b_blkno == bp->b_lblkno) 1016 VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno, 1017 NULL, NULL); 1018 buflist->bs_nchildren = i + 1; 1019 return (buflist); 1020 }
Cache object: 5ad6af71770fe311a5c443a7a0959154
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