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: src/sys/kern/vfs_cluster.c,v 1.92.2.9 2001/11/18 07:10:59 dillon Exp $ 37 * $DragonFly: src/sys/kern/vfs_cluster.c,v 1.20 2006/03/26 07:56:54 swildner Exp $ 38 */ 39 40 #include "opt_debug_cluster.h" 41 42 #include <sys/param.h> 43 #include <sys/systm.h> 44 #include <sys/kernel.h> 45 #include <sys/proc.h> 46 #include <sys/buf.h> 47 #include <sys/vnode.h> 48 #include <sys/malloc.h> 49 #include <sys/mount.h> 50 #include <sys/resourcevar.h> 51 #include <sys/vmmeter.h> 52 #include <vm/vm.h> 53 #include <vm/vm_object.h> 54 #include <vm/vm_page.h> 55 #include <sys/sysctl.h> 56 #include <sys/buf2.h> 57 #include <vm/vm_page2.h> 58 59 #if defined(CLUSTERDEBUG) 60 #include <sys/sysctl.h> 61 static int rcluster= 0; 62 SYSCTL_INT(_debug, OID_AUTO, rcluster, CTLFLAG_RW, &rcluster, 0, ""); 63 #endif 64 65 static MALLOC_DEFINE(M_SEGMENT, "cluster_save", "cluster_save buffer"); 66 67 static struct cluster_save * 68 cluster_collectbufs (struct vnode *vp, struct buf *last_bp, 69 int lblocksize); 70 static struct buf * 71 cluster_rbuild (struct vnode *vp, off_t filesize, off_t loffset, 72 off_t doffset, int size, int run, struct buf *fbp); 73 static void cluster_callback (struct bio *); 74 75 76 static int write_behind = 1; 77 SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0, ""); 78 79 extern vm_page_t bogus_page; 80 81 extern int cluster_pbuf_freecnt; 82 83 /* 84 * Maximum number of blocks for read-ahead. 85 */ 86 #define MAXRA 32 87 88 /* 89 * This replaces bread. 90 */ 91 int 92 cluster_read(struct vnode *vp, off_t filesize, off_t loffset, 93 int size, int totread, int seqcount, struct buf **bpp) 94 { 95 struct buf *bp, *rbp, *reqbp; 96 off_t origoffset; 97 off_t doffset; 98 int error; 99 int i; 100 int maxra, racluster; 101 102 error = 0; 103 104 /* 105 * Try to limit the amount of read-ahead by a few 106 * ad-hoc parameters. This needs work!!! 107 */ 108 racluster = vp->v_mount->mnt_iosize_max / size; 109 maxra = 2 * racluster + (totread / size); 110 if (maxra > MAXRA) 111 maxra = MAXRA; 112 if (maxra > nbuf/8) 113 maxra = nbuf/8; 114 115 /* 116 * get the requested block 117 */ 118 *bpp = reqbp = bp = getblk(vp, loffset, size, 0, 0); 119 origoffset = loffset; 120 121 /* 122 * if it is in the cache, then check to see if the reads have been 123 * sequential. If they have, then try some read-ahead, otherwise 124 * back-off on prospective read-aheads. 125 */ 126 if (bp->b_flags & B_CACHE) { 127 if (!seqcount) { 128 return 0; 129 } else if ((bp->b_flags & B_RAM) == 0) { 130 return 0; 131 } else { 132 struct buf *tbp; 133 bp->b_flags &= ~B_RAM; 134 /* 135 * We do the crit here so that there is no window 136 * between the findblk and the b_usecount increment 137 * below. We opt to keep the crit out of the loop 138 * for efficiency. 139 */ 140 crit_enter(); 141 for (i = 1; i < maxra; i++) { 142 if (!(tbp = findblk(vp, loffset + i * size))) { 143 break; 144 } 145 146 /* 147 * Set another read-ahead mark so we know 148 * to check again. 149 */ 150 if (((i % racluster) == (racluster - 1)) || 151 (i == (maxra - 1))) 152 tbp->b_flags |= B_RAM; 153 } 154 crit_exit(); 155 if (i >= maxra) { 156 return 0; 157 } 158 loffset += i * size; 159 } 160 reqbp = bp = NULL; 161 } else { 162 off_t firstread = bp->b_loffset; 163 int nblks; 164 165 KASSERT(firstread != NOOFFSET, 166 ("cluster_read: no buffer offset")); 167 if (firstread + totread > filesize) 168 totread = (int)(filesize - firstread); 169 nblks = totread / size; 170 if (nblks) { 171 int burstbytes; 172 173 if (nblks > racluster) 174 nblks = racluster; 175 176 error = VOP_BMAP(vp, loffset, NULL, 177 &doffset, &burstbytes, NULL); 178 if (error) 179 goto single_block_read; 180 if (doffset == NOOFFSET) 181 goto single_block_read; 182 if (burstbytes < size * 2) 183 goto single_block_read; 184 if (nblks > burstbytes / size) 185 nblks = burstbytes / size; 186 187 bp = cluster_rbuild(vp, filesize, loffset, 188 doffset, size, nblks, bp); 189 loffset += bp->b_bufsize; 190 } else { 191 single_block_read: 192 /* 193 * if it isn't in the cache, then get a chunk from 194 * disk if sequential, otherwise just get the block. 195 */ 196 bp->b_flags |= B_READ | B_RAM; 197 loffset += size; 198 } 199 } 200 201 /* 202 * If we have been doing sequential I/O, then do some read-ahead. 203 */ 204 rbp = NULL; 205 if (seqcount && 206 loffset < origoffset + seqcount * size && 207 loffset + size <= filesize 208 ) { 209 rbp = getblk(vp, loffset, size, 0, 0); 210 if ((rbp->b_flags & B_CACHE) == 0) { 211 int nblksread; 212 int ntoread; 213 int burstbytes; 214 215 error = VOP_BMAP(vp, loffset, NULL, 216 &doffset, &burstbytes, NULL); 217 if (error || doffset == NOOFFSET) { 218 rbp->b_flags &= ~(B_ASYNC | B_READ); 219 brelse(rbp); 220 rbp = NULL; 221 goto no_read_ahead; 222 } 223 ntoread = burstbytes / size; 224 nblksread = (totread + size - 1) / size; 225 if (seqcount < nblksread) 226 seqcount = nblksread; 227 if (seqcount < ntoread) 228 ntoread = seqcount; 229 230 rbp->b_flags |= B_READ | B_ASYNC | B_RAM; 231 if (burstbytes) { 232 rbp = cluster_rbuild(vp, filesize, loffset, 233 doffset, size, 234 ntoread, rbp); 235 } else { 236 rbp->b_bio2.bio_offset = doffset; 237 } 238 } 239 } 240 no_read_ahead: 241 242 /* 243 * Handle the synchronous read 244 */ 245 if (bp) { 246 #if defined(CLUSTERDEBUG) 247 if (rcluster) 248 printf("S(%lld,%d,%d) ", 249 bp->b_loffset, bp->b_bcount, seqcount); 250 #endif 251 if ((bp->b_flags & B_CLUSTER) == 0) { 252 vfs_busy_pages(bp, 0); 253 } 254 bp->b_flags &= ~(B_ERROR|B_INVAL); 255 if ((bp->b_flags & B_ASYNC) || bp->b_bio1.bio_done != NULL) 256 BUF_KERNPROC(bp); 257 vn_strategy(vp, &bp->b_bio1); 258 error = bp->b_error; 259 } 260 261 /* 262 * And if we have read-aheads, do them too 263 */ 264 if (rbp) { 265 if (error) { 266 rbp->b_flags &= ~(B_ASYNC | B_READ); 267 brelse(rbp); 268 } else if (rbp->b_flags & B_CACHE) { 269 rbp->b_flags &= ~(B_ASYNC | B_READ); 270 bqrelse(rbp); 271 } else { 272 #if defined(CLUSTERDEBUG) 273 if (rcluster) { 274 if (bp) 275 printf("A+(%lld,%d,%lld,%d) ", 276 rbp->b_loffset, rbp->b_bcount, 277 rbp->b_loffset - origoffset, 278 seqcount); 279 else 280 printf("A(%lld,%d,%lld,%d) ", 281 rbp->b_loffset, rbp->b_bcount, 282 rbp->b_loffset - origoffset, 283 seqcount); 284 } 285 #endif 286 287 if ((rbp->b_flags & B_CLUSTER) == 0) { 288 vfs_busy_pages(rbp, 0); 289 } 290 rbp->b_flags &= ~(B_ERROR|B_INVAL); 291 if ((rbp->b_flags & B_ASYNC) || rbp->b_bio1.bio_done != NULL) 292 BUF_KERNPROC(rbp); 293 vn_strategy(vp, &rbp->b_bio1); 294 } 295 } 296 if (reqbp) 297 return (biowait(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(struct vnode *vp, off_t filesize, off_t loffset, 309 off_t doffset, int size, int run, struct buf *fbp) 310 { 311 struct buf *bp, *tbp; 312 off_t boffset; 313 int i, j; 314 315 KASSERT(size == vp->v_mount->mnt_stat.f_iosize, 316 ("cluster_rbuild: size %d != filesize %ld\n", 317 size, vp->v_mount->mnt_stat.f_iosize)); 318 319 /* 320 * avoid a division 321 */ 322 while (loffset + run * size > filesize) { 323 --run; 324 } 325 326 tbp = fbp; 327 tbp->b_flags |= B_READ; 328 tbp->b_bio2.bio_offset = doffset; 329 if( (tbp->b_flags & B_MALLOC) || 330 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1) ) 331 return tbp; 332 333 bp = trypbuf(&cluster_pbuf_freecnt); 334 if (bp == 0) 335 return tbp; 336 337 /* 338 * We are synthesizing a buffer out of vm_page_t's, but 339 * if the block size is not page aligned then the starting 340 * address may not be either. Inherit the b_data offset 341 * from the original buffer. 342 */ 343 bp->b_data = (char *)((vm_offset_t)bp->b_data | 344 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 345 bp->b_flags = B_ASYNC | B_READ | B_CLUSTER | B_VMIO; 346 bp->b_bio1.bio_done = cluster_callback; 347 bp->b_bio1.bio_caller_info1.cluster_head = NULL; 348 bp->b_bio1.bio_caller_info2.cluster_tail = NULL; 349 bp->b_loffset = loffset; 350 bp->b_bio2.bio_offset = NOOFFSET; 351 KASSERT(bp->b_loffset != NOOFFSET, 352 ("cluster_rbuild: no buffer offset")); 353 pbgetvp(vp, bp); 354 355 bp->b_bcount = 0; 356 bp->b_bufsize = 0; 357 bp->b_xio.xio_npages = 0; 358 359 for (boffset = doffset, i = 0; i < run; ++i, boffset += size) { 360 if (i != 0) { 361 if ((bp->b_xio.xio_npages * PAGE_SIZE) + 362 round_page(size) > vp->v_mount->mnt_iosize_max) { 363 break; 364 } 365 366 /* 367 * Shortcut some checks and try to avoid buffers that 368 * would block in the lock. The same checks have to 369 * be made again after we officially get the buffer. 370 */ 371 if ((tbp = findblk(vp, loffset + i * size)) != NULL) { 372 if (BUF_LOCK(tbp, LK_EXCLUSIVE | LK_NOWAIT)) 373 break; 374 BUF_UNLOCK(tbp); 375 376 for (j = 0; j < tbp->b_xio.xio_npages; j++) { 377 if (tbp->b_xio.xio_pages[j]->valid) 378 break; 379 } 380 381 if (j != tbp->b_xio.xio_npages) 382 break; 383 384 if (tbp->b_bcount != size) 385 break; 386 } 387 388 tbp = getblk(vp, loffset + i * size, size, 0, 0); 389 390 /* 391 * Stop scanning if the buffer is fuly valid 392 * (marked B_CACHE), or locked (may be doing a 393 * background write), or if the buffer is not 394 * VMIO backed. The clustering code can only deal 395 * with VMIO-backed buffers. 396 */ 397 if ((tbp->b_flags & (B_CACHE|B_LOCKED)) || 398 (tbp->b_flags & B_VMIO) == 0) { 399 bqrelse(tbp); 400 break; 401 } 402 403 /* 404 * The buffer must be completely invalid in order to 405 * take part in the cluster. If it is partially valid 406 * then we stop. 407 */ 408 for (j = 0;j < tbp->b_xio.xio_npages; j++) { 409 if (tbp->b_xio.xio_pages[j]->valid) 410 break; 411 } 412 if (j != tbp->b_xio.xio_npages) { 413 bqrelse(tbp); 414 break; 415 } 416 417 /* 418 * Set a read-ahead mark as appropriate 419 */ 420 if (i == 1 || i == (run - 1)) 421 tbp->b_flags |= B_RAM; 422 423 /* 424 * Set the buffer up for an async read (XXX should 425 * we do this only if we do not wind up brelse()ing?). 426 * Set the block number if it isn't set, otherwise 427 * if it is make sure it matches the block number we 428 * expect. 429 */ 430 tbp->b_flags |= B_READ | B_ASYNC; 431 if (tbp->b_bio2.bio_offset == NOOFFSET) { 432 tbp->b_bio2.bio_offset = boffset; 433 } else if (tbp->b_bio2.bio_offset != boffset) { 434 brelse(tbp); 435 break; 436 } 437 } 438 /* 439 * XXX fbp from caller may not be B_ASYNC, but we are going 440 * to biodone() it in cluster_callback() anyway 441 */ 442 BUF_KERNPROC(tbp); 443 cluster_append(&bp->b_bio1, tbp); 444 for (j = 0; j < tbp->b_xio.xio_npages; ++j) { 445 vm_page_t m; 446 m = tbp->b_xio.xio_pages[j]; 447 vm_page_io_start(m); 448 vm_object_pip_add(m->object, 1); 449 if ((bp->b_xio.xio_npages == 0) || 450 (bp->b_xio.xio_pages[bp->b_xio.xio_npages-1] != m)) { 451 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 452 bp->b_xio.xio_npages++; 453 } 454 if ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) 455 tbp->b_xio.xio_pages[j] = bogus_page; 456 } 457 /* 458 * XXX shouldn't this be += size for both, like in 459 * cluster_wbuild()? 460 * 461 * Don't inherit tbp->b_bufsize as it may be larger due to 462 * a non-page-aligned size. Instead just aggregate using 463 * 'size'. 464 */ 465 if (tbp->b_bcount != size) 466 printf("warning: tbp->b_bcount wrong %d vs %d\n", tbp->b_bcount, size); 467 if (tbp->b_bufsize != size) 468 printf("warning: tbp->b_bufsize wrong %d vs %d\n", tbp->b_bufsize, size); 469 bp->b_bcount += size; 470 bp->b_bufsize += size; 471 } 472 473 /* 474 * Fully valid pages in the cluster are already good and do not need 475 * to be re-read from disk. Replace the page with bogus_page 476 */ 477 for (j = 0; j < bp->b_xio.xio_npages; j++) { 478 if ((bp->b_xio.xio_pages[j]->valid & VM_PAGE_BITS_ALL) == 479 VM_PAGE_BITS_ALL) { 480 bp->b_xio.xio_pages[j] = bogus_page; 481 } 482 } 483 if (bp->b_bufsize > bp->b_kvasize) 484 panic("cluster_rbuild: b_bufsize(%d) > b_kvasize(%d)", 485 bp->b_bufsize, bp->b_kvasize); 486 bp->b_kvasize = bp->b_bufsize; 487 488 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 489 (vm_page_t *)bp->b_xio.xio_pages, bp->b_xio.xio_npages); 490 return (bp); 491 } 492 493 /* 494 * Cleanup after a clustered read or write. 495 * This is complicated by the fact that any of the buffers might have 496 * extra memory (if there were no empty buffer headers at allocbuf time) 497 * that we will need to shift around. 498 * 499 * The returned bio is &bp->b_bio1 500 */ 501 void 502 cluster_callback(struct bio *bio) 503 { 504 struct buf *bp = bio->bio_buf; 505 struct buf *tbp; 506 int error = 0; 507 508 /* 509 * Must propogate errors to all the components. 510 */ 511 if (bp->b_flags & B_ERROR) 512 error = bp->b_error; 513 514 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_xio.xio_npages); 515 /* 516 * Move memory from the large cluster buffer into the component 517 * buffers and mark IO as done on these. Since the memory map 518 * is the same, no actual copying is required. 519 */ 520 while ((tbp = bio->bio_caller_info1.cluster_head) != NULL) { 521 bio->bio_caller_info1.cluster_head = tbp->b_cluster_next; 522 if (error) { 523 tbp->b_flags |= B_ERROR; 524 tbp->b_error = error; 525 } else { 526 tbp->b_dirtyoff = tbp->b_dirtyend = 0; 527 tbp->b_flags &= ~(B_ERROR|B_INVAL); 528 /* 529 * XXX the bdwrite()/bqrelse() issued during 530 * cluster building clears B_RELBUF (see bqrelse() 531 * comment). If direct I/O was specified, we have 532 * to restore it here to allow the buffer and VM 533 * to be freed. 534 */ 535 if (tbp->b_flags & B_DIRECT) 536 tbp->b_flags |= B_RELBUF; 537 } 538 biodone(&tbp->b_bio1); 539 } 540 relpbuf(bp, &cluster_pbuf_freecnt); 541 } 542 543 /* 544 * cluster_wbuild_wb: 545 * 546 * Implement modified write build for cluster. 547 * 548 * write_behind = 0 write behind disabled 549 * write_behind = 1 write behind normal (default) 550 * write_behind = 2 write behind backed-off 551 */ 552 553 static __inline int 554 cluster_wbuild_wb(struct vnode *vp, int size, off_t start_loffset, int len) 555 { 556 int r = 0; 557 558 switch(write_behind) { 559 case 2: 560 if (start_loffset < len) 561 break; 562 start_loffset -= len; 563 /* fall through */ 564 case 1: 565 r = cluster_wbuild(vp, size, start_loffset, len); 566 /* fall through */ 567 default: 568 /* fall through */ 569 break; 570 } 571 return(r); 572 } 573 574 /* 575 * Do clustered write for FFS. 576 * 577 * Three cases: 578 * 1. Write is not sequential (write asynchronously) 579 * Write is sequential: 580 * 2. beginning of cluster - begin cluster 581 * 3. middle of a cluster - add to cluster 582 * 4. end of a cluster - asynchronously write cluster 583 */ 584 void 585 cluster_write(struct buf *bp, off_t filesize, int seqcount) 586 { 587 struct vnode *vp; 588 off_t loffset; 589 int maxclen, cursize; 590 int lblocksize; 591 int async; 592 593 vp = bp->b_vp; 594 if (vp->v_type == VREG) { 595 async = vp->v_mount->mnt_flag & MNT_ASYNC; 596 lblocksize = vp->v_mount->mnt_stat.f_iosize; 597 } else { 598 async = 0; 599 lblocksize = bp->b_bufsize; 600 } 601 loffset = bp->b_loffset; 602 KASSERT(bp->b_loffset != NOOFFSET, 603 ("cluster_write: no buffer offset")); 604 605 /* Initialize vnode to beginning of file. */ 606 if (loffset == 0) 607 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0; 608 609 if (vp->v_clen == 0 || loffset != vp->v_lastw + lblocksize || 610 bp->b_bio2.bio_offset == NOOFFSET || 611 (bp->b_bio2.bio_offset != vp->v_lasta + lblocksize)) { 612 maxclen = vp->v_mount->mnt_iosize_max; 613 if (vp->v_clen != 0) { 614 /* 615 * Next block is not sequential. 616 * 617 * If we are not writing at end of file, the process 618 * seeked to another point in the file since its last 619 * write, or we have reached our maximum cluster size, 620 * then push the previous cluster. Otherwise try 621 * reallocating to make it sequential. 622 * 623 * Change to algorithm: only push previous cluster if 624 * it was sequential from the point of view of the 625 * seqcount heuristic, otherwise leave the buffer 626 * intact so we can potentially optimize the I/O 627 * later on in the buf_daemon or update daemon 628 * flush. 629 */ 630 cursize = vp->v_lastw - vp->v_cstart + lblocksize; 631 if (bp->b_loffset + lblocksize != filesize || 632 loffset != vp->v_lastw + lblocksize || vp->v_clen <= cursize) { 633 if (!async && seqcount > 0) { 634 cluster_wbuild_wb(vp, lblocksize, 635 vp->v_cstart, cursize); 636 } 637 } else { 638 struct buf **bpp, **endbp; 639 struct cluster_save *buflist; 640 641 buflist = cluster_collectbufs(vp, bp, 642 lblocksize); 643 endbp = &buflist->bs_children 644 [buflist->bs_nchildren - 1]; 645 if (VOP_REALLOCBLKS(vp, buflist)) { 646 /* 647 * Failed, push the previous cluster 648 * if *really* writing sequentially 649 * in the logical file (seqcount > 1), 650 * otherwise delay it in the hopes that 651 * the low level disk driver can 652 * optimize the write ordering. 653 */ 654 for (bpp = buflist->bs_children; 655 bpp < endbp; bpp++) 656 brelse(*bpp); 657 free(buflist, M_SEGMENT); 658 if (seqcount > 1) { 659 cluster_wbuild_wb(vp, 660 lblocksize, vp->v_cstart, 661 cursize); 662 } 663 } else { 664 /* 665 * Succeeded, keep building cluster. 666 */ 667 for (bpp = buflist->bs_children; 668 bpp <= endbp; bpp++) 669 bdwrite(*bpp); 670 free(buflist, M_SEGMENT); 671 vp->v_lastw = loffset; 672 vp->v_lasta = bp->b_bio2.bio_offset; 673 return; 674 } 675 } 676 } 677 /* 678 * Consider beginning a cluster. If at end of file, make 679 * cluster as large as possible, otherwise find size of 680 * existing cluster. 681 */ 682 if ((vp->v_type == VREG) && 683 bp->b_loffset + lblocksize != filesize && 684 (bp->b_bio2.bio_offset == NOOFFSET) && 685 (VOP_BMAP(vp, loffset, NULL, &bp->b_bio2.bio_offset, &maxclen, NULL) || 686 bp->b_bio2.bio_offset == NOOFFSET)) { 687 bawrite(bp); 688 vp->v_clen = 0; 689 vp->v_lasta = bp->b_bio2.bio_offset; 690 vp->v_cstart = loffset + lblocksize; 691 vp->v_lastw = loffset; 692 return; 693 } 694 if (maxclen > lblocksize) 695 vp->v_clen = maxclen - lblocksize; 696 else 697 vp->v_clen = 0; 698 if (!async && vp->v_clen == 0) { /* I/O not contiguous */ 699 vp->v_cstart = loffset + lblocksize; 700 bawrite(bp); 701 } else { /* Wait for rest of cluster */ 702 vp->v_cstart = loffset; 703 bdwrite(bp); 704 } 705 } else if (loffset == vp->v_cstart + vp->v_clen) { 706 /* 707 * At end of cluster, write it out if seqcount tells us we 708 * are operating sequentially, otherwise let the buf or 709 * update daemon handle it. 710 */ 711 bdwrite(bp); 712 if (seqcount > 1) 713 cluster_wbuild_wb(vp, lblocksize, vp->v_cstart, 714 vp->v_clen + lblocksize); 715 vp->v_clen = 0; 716 vp->v_cstart = loffset + lblocksize; 717 } else if (vm_page_count_severe()) { 718 /* 719 * We are low on memory, get it going NOW 720 */ 721 bawrite(bp); 722 } else { 723 /* 724 * In the middle of a cluster, so just delay the I/O for now. 725 */ 726 bdwrite(bp); 727 } 728 vp->v_lastw = loffset; 729 vp->v_lasta = bp->b_bio2.bio_offset; 730 } 731 732 733 /* 734 * This is an awful lot like cluster_rbuild...wish they could be combined. 735 * The last lbn argument is the current block on which I/O is being 736 * performed. Check to see that it doesn't fall in the middle of 737 * the current block (if last_bp == NULL). 738 */ 739 int 740 cluster_wbuild(struct vnode *vp, int size, off_t start_loffset, int bytes) 741 { 742 struct buf *bp, *tbp; 743 int i, j; 744 int totalwritten = 0; 745 746 while (bytes > 0) { 747 crit_enter(); 748 /* 749 * If the buffer is not delayed-write (i.e. dirty), or it 750 * is delayed-write but either locked or inval, it cannot 751 * partake in the clustered write. 752 */ 753 if (((tbp = findblk(vp, start_loffset)) == NULL) || 754 ((tbp->b_flags & (B_LOCKED | B_INVAL | B_DELWRI)) != B_DELWRI) || 755 BUF_LOCK(tbp, LK_EXCLUSIVE | LK_NOWAIT)) { 756 start_loffset += size; 757 bytes -= size; 758 crit_exit(); 759 continue; 760 } 761 bremfree(tbp); 762 tbp->b_flags &= ~B_DONE; 763 crit_exit(); 764 765 /* 766 * Extra memory in the buffer, punt on this buffer. 767 * XXX we could handle this in most cases, but we would 768 * have to push the extra memory down to after our max 769 * possible cluster size and then potentially pull it back 770 * up if the cluster was terminated prematurely--too much 771 * hassle. 772 */ 773 if (((tbp->b_flags & (B_CLUSTEROK|B_MALLOC)) != B_CLUSTEROK) || 774 (tbp->b_bcount != tbp->b_bufsize) || 775 (tbp->b_bcount != size) || 776 (bytes == size) || 777 ((bp = getpbuf(&cluster_pbuf_freecnt)) == NULL)) { 778 totalwritten += tbp->b_bufsize; 779 bawrite(tbp); 780 start_loffset += size; 781 bytes -= size; 782 continue; 783 } 784 785 /* 786 * We got a pbuf to make the cluster in. 787 * so initialise it. 788 */ 789 bp->b_bcount = 0; 790 bp->b_bufsize = 0; 791 bp->b_xio.xio_npages = 0; 792 bp->b_loffset = tbp->b_loffset; 793 bp->b_bio2.bio_offset = tbp->b_bio2.bio_offset; 794 795 /* 796 * We are synthesizing a buffer out of vm_page_t's, but 797 * if the block size is not page aligned then the starting 798 * address may not be either. Inherit the b_data offset 799 * from the original buffer. 800 */ 801 bp->b_data = (char *)((vm_offset_t)bp->b_data | 802 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 803 bp->b_flags |= B_CLUSTER | 804 (tbp->b_flags & (B_VMIO | B_NEEDCOMMIT | B_NOWDRAIN)); 805 bp->b_bio1.bio_done = cluster_callback; 806 bp->b_bio1.bio_caller_info1.cluster_head = NULL; 807 bp->b_bio1.bio_caller_info2.cluster_tail = NULL; 808 pbgetvp(vp, bp); 809 /* 810 * From this location in the file, scan forward to see 811 * if there are buffers with adjacent data that need to 812 * be written as well. 813 */ 814 for (i = 0; i < bytes; (i += size), (start_loffset += size)) { 815 if (i != 0) { /* If not the first buffer */ 816 crit_enter(); 817 /* 818 * If the adjacent data is not even in core it 819 * can't need to be written. 820 */ 821 if ((tbp = findblk(vp, start_loffset)) == NULL) { 822 crit_exit(); 823 break; 824 } 825 826 /* 827 * If it IS in core, but has different 828 * characteristics, or is locked (which 829 * means it could be undergoing a background 830 * I/O or be in a weird state), then don't 831 * cluster with it. 832 */ 833 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK | 834 B_INVAL | B_DELWRI | B_NEEDCOMMIT)) 835 != (B_DELWRI | B_CLUSTEROK | 836 (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) || 837 (tbp->b_flags & B_LOCKED) || 838 BUF_LOCK(tbp, LK_EXCLUSIVE | LK_NOWAIT)) { 839 crit_exit(); 840 break; 841 } 842 843 /* 844 * Check that the combined cluster 845 * would make sense with regard to pages 846 * and would not be too large 847 */ 848 if ((tbp->b_bcount != size) || 849 ((bp->b_bio2.bio_offset + i) != 850 tbp->b_bio2.bio_offset) || 851 ((tbp->b_xio.xio_npages + bp->b_xio.xio_npages) > 852 (vp->v_mount->mnt_iosize_max / PAGE_SIZE))) { 853 BUF_UNLOCK(tbp); 854 crit_exit(); 855 break; 856 } 857 /* 858 * Ok, it's passed all the tests, 859 * so remove it from the free list 860 * and mark it busy. We will use it. 861 */ 862 bremfree(tbp); 863 tbp->b_flags &= ~B_DONE; 864 crit_exit(); 865 } /* end of code for non-first buffers only */ 866 867 /* 868 * If the IO is via the VM then we do some 869 * special VM hackery (yuck). Since the buffer's 870 * block size may not be page-aligned it is possible 871 * for a page to be shared between two buffers. We 872 * have to get rid of the duplication when building 873 * the cluster. 874 */ 875 if (tbp->b_flags & B_VMIO) { 876 vm_page_t m; 877 878 if (i != 0) { /* if not first buffer */ 879 for (j = 0; j < tbp->b_xio.xio_npages; ++j) { 880 m = tbp->b_xio.xio_pages[j]; 881 if (m->flags & PG_BUSY) { 882 bqrelse(tbp); 883 goto finishcluster; 884 } 885 } 886 } 887 888 for (j = 0; j < tbp->b_xio.xio_npages; ++j) { 889 m = tbp->b_xio.xio_pages[j]; 890 vm_page_io_start(m); 891 vm_object_pip_add(m->object, 1); 892 if ((bp->b_xio.xio_npages == 0) || 893 (bp->b_xio.xio_pages[bp->b_xio.xio_npages - 1] != m)) { 894 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 895 bp->b_xio.xio_npages++; 896 } 897 } 898 } 899 bp->b_bcount += size; 900 bp->b_bufsize += size; 901 902 crit_enter(); 903 bundirty(tbp); 904 tbp->b_flags &= ~(B_READ | B_DONE | B_ERROR); 905 tbp->b_flags |= B_ASYNC; 906 crit_exit(); 907 BUF_KERNPROC(tbp); 908 cluster_append(&bp->b_bio1, tbp); 909 910 /* 911 * check for latent dependencies to be handled 912 */ 913 if (LIST_FIRST(&tbp->b_dep) != NULL && bioops.io_start) 914 (*bioops.io_start)(tbp); 915 916 } 917 finishcluster: 918 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 919 (vm_page_t *) bp->b_xio.xio_pages, bp->b_xio.xio_npages); 920 if (bp->b_bufsize > bp->b_kvasize) 921 panic( 922 "cluster_wbuild: b_bufsize(%d) > b_kvasize(%d)\n", 923 bp->b_bufsize, bp->b_kvasize); 924 bp->b_kvasize = bp->b_bufsize; 925 totalwritten += bp->b_bufsize; 926 bp->b_dirtyoff = 0; 927 bp->b_dirtyend = bp->b_bufsize; 928 bawrite(bp); 929 930 bytes -= i; 931 } 932 return totalwritten; 933 } 934 935 /* 936 * Collect together all the buffers in a cluster. 937 * Plus add one additional buffer. 938 */ 939 static struct cluster_save * 940 cluster_collectbufs(struct vnode *vp, struct buf *last_bp, int lblocksize) 941 { 942 struct cluster_save *buflist; 943 struct buf *bp; 944 off_t loffset; 945 int i, len; 946 947 len = (int)(vp->v_lastw - vp->v_cstart + lblocksize) / lblocksize; 948 buflist = malloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist), 949 M_SEGMENT, M_WAITOK); 950 buflist->bs_nchildren = 0; 951 buflist->bs_children = (struct buf **) (buflist + 1); 952 for (loffset = vp->v_cstart, i = 0; i < len; (loffset += lblocksize), i++) { 953 (void) bread(vp, loffset, last_bp->b_bcount, &bp); 954 buflist->bs_children[i] = bp; 955 if (bp->b_bio2.bio_offset == NOOFFSET) { 956 VOP_BMAP(bp->b_vp, bp->b_loffset, NULL, 957 &bp->b_bio2.bio_offset, NULL, NULL); 958 } 959 } 960 buflist->bs_children[i] = bp = last_bp; 961 if (bp->b_bio2.bio_offset == NOOFFSET) { 962 VOP_BMAP(bp->b_vp, bp->b_loffset, NULL, 963 &bp->b_bio2.bio_offset, NULL, NULL); 964 } 965 buflist->bs_nchildren = i + 1; 966 return (buflist); 967 } 968 969 void 970 cluster_append(struct bio *bio, struct buf *tbp) 971 { 972 tbp->b_cluster_next = NULL; 973 if (bio->bio_caller_info1.cluster_head == NULL) { 974 bio->bio_caller_info1.cluster_head = tbp; 975 bio->bio_caller_info2.cluster_tail = tbp; 976 } else { 977 bio->bio_caller_info2.cluster_tail->b_cluster_next = tbp; 978 bio->bio_caller_info2.cluster_tail = tbp; 979 } 980 } 981 982