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 1.11 2004/07/14 03:10:17 hmp 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 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 76 extern vm_page_t bogus_page; 77 78 extern int cluster_pbuf_freecnt; 79 80 /* 81 * Maximum number of blocks for read-ahead. 82 */ 83 #define MAXRA 32 84 85 /* 86 * This replaces bread. 87 */ 88 int 89 cluster_read(struct vnode *vp, u_quad_t filesize, daddr_t lblkno, 90 long size, long totread, int seqcount, struct buf **bpp) 91 { 92 struct buf *bp, *rbp, *reqbp; 93 daddr_t blkno, origblkno; 94 int error, num_ra; 95 int i; 96 int maxra, racluster; 97 long origtotread; 98 99 error = 0; 100 101 /* 102 * Try to limit the amount of read-ahead by a few 103 * ad-hoc parameters. This needs work!!! 104 */ 105 racluster = vp->v_mount->mnt_iosize_max / size; 106 maxra = 2 * racluster + (totread / size); 107 if (maxra > MAXRA) 108 maxra = MAXRA; 109 if (maxra > nbuf/8) 110 maxra = nbuf/8; 111 112 /* 113 * get the requested block 114 */ 115 *bpp = reqbp = bp = getblk(vp, lblkno, size, 0, 0); 116 origblkno = lblkno; 117 origtotread = totread; 118 119 /* 120 * if it is in the cache, then check to see if the reads have been 121 * sequential. If they have, then try some read-ahead, otherwise 122 * back-off on prospective read-aheads. 123 */ 124 if (bp->b_flags & B_CACHE) { 125 if (!seqcount) { 126 return 0; 127 } else if ((bp->b_flags & B_RAM) == 0) { 128 return 0; 129 } else { 130 int s; 131 struct buf *tbp; 132 bp->b_flags &= ~B_RAM; 133 /* 134 * We do the spl here so that there is no window 135 * between the incore and the b_usecount increment 136 * below. We opt to keep the spl out of the loop 137 * for efficiency. 138 */ 139 s = splbio(); 140 for (i = 1; i < maxra; i++) { 141 142 if (!(tbp = incore(vp, lblkno+i))) { 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 splx(s); 155 if (i >= maxra) { 156 return 0; 157 } 158 lblkno += i; 159 } 160 reqbp = bp = NULL; 161 } else { 162 off_t firstread = bp->b_offset; 163 164 KASSERT(bp->b_offset != NOOFFSET, 165 ("cluster_read: no buffer offset")); 166 if (firstread + totread > filesize) 167 totread = filesize - firstread; 168 if (totread > size) { 169 int nblks = 0; 170 int ncontigafter; 171 while (totread > 0) { 172 nblks++; 173 totread -= size; 174 } 175 if (nblks == 1) 176 goto single_block_read; 177 if (nblks > racluster) 178 nblks = racluster; 179 180 error = VOP_BMAP(vp, lblkno, NULL, 181 &blkno, &ncontigafter, NULL); 182 if (error) 183 goto single_block_read; 184 if (blkno == -1) 185 goto single_block_read; 186 if (ncontigafter == 0) 187 goto single_block_read; 188 if (ncontigafter + 1 < nblks) 189 nblks = ncontigafter + 1; 190 191 bp = cluster_rbuild(vp, filesize, lblkno, 192 blkno, size, nblks, bp); 193 lblkno += (bp->b_bufsize / size); 194 } else { 195 single_block_read: 196 /* 197 * if it isn't in the cache, then get a chunk from 198 * disk if sequential, otherwise just get the block. 199 */ 200 bp->b_flags |= B_READ | B_RAM; 201 lblkno += 1; 202 } 203 } 204 205 /* 206 * if we have been doing sequential I/O, then do some read-ahead 207 */ 208 rbp = NULL; 209 if (seqcount && (lblkno < (origblkno + seqcount))) { 210 /* 211 * we now build the read-ahead buffer if it is desirable. 212 */ 213 if (((u_quad_t)(lblkno + 1) * size) <= filesize && 214 !(error = VOP_BMAP(vp, lblkno, NULL, &blkno, &num_ra, NULL)) && 215 blkno != -1) { 216 int nblksread; 217 int ntoread = num_ra + 1; 218 nblksread = (origtotread + size - 1) / size; 219 if (seqcount < nblksread) 220 seqcount = nblksread; 221 if (seqcount < ntoread) 222 ntoread = seqcount; 223 if (num_ra) { 224 rbp = cluster_rbuild(vp, filesize, lblkno, 225 blkno, size, ntoread, NULL); 226 } else { 227 rbp = getblk(vp, lblkno, size, 0, 0); 228 rbp->b_flags |= B_READ | B_ASYNC | B_RAM; 229 rbp->b_blkno = blkno; 230 } 231 } 232 } 233 234 /* 235 * handle the synchronous read 236 */ 237 if (bp) { 238 #if defined(CLUSTERDEBUG) 239 if (rcluster) 240 printf("S(%ld,%ld,%d) ", 241 (long)bp->b_lblkno, bp->b_bcount, seqcount); 242 #endif 243 if ((bp->b_flags & B_CLUSTER) == 0) { 244 vfs_busy_pages(bp, 0); 245 } 246 bp->b_flags &= ~(B_ERROR|B_INVAL); 247 if (bp->b_flags & (B_ASYNC|B_CALL)) 248 BUF_KERNPROC(bp); 249 error = VOP_STRATEGY(vp, bp); 250 } 251 252 /* 253 * and if we have read-aheads, do them too 254 */ 255 if (rbp) { 256 if (error) { 257 rbp->b_flags &= ~(B_ASYNC | B_READ); 258 brelse(rbp); 259 } else if (rbp->b_flags & B_CACHE) { 260 rbp->b_flags &= ~(B_ASYNC | B_READ); 261 bqrelse(rbp); 262 } else { 263 #if defined(CLUSTERDEBUG) 264 if (rcluster) { 265 if (bp) 266 printf("A+(%ld,%ld,%ld,%d) ", 267 (long)rbp->b_lblkno, rbp->b_bcount, 268 (long)(rbp->b_lblkno - origblkno), 269 seqcount); 270 else 271 printf("A(%ld,%ld,%ld,%d) ", 272 (long)rbp->b_lblkno, rbp->b_bcount, 273 (long)(rbp->b_lblkno - origblkno), 274 seqcount); 275 } 276 #endif 277 278 if ((rbp->b_flags & B_CLUSTER) == 0) { 279 vfs_busy_pages(rbp, 0); 280 } 281 rbp->b_flags &= ~(B_ERROR|B_INVAL); 282 if (rbp->b_flags & (B_ASYNC|B_CALL)) 283 BUF_KERNPROC(rbp); 284 (void) VOP_STRATEGY(vp, rbp); 285 } 286 } 287 if (reqbp) 288 return (biowait(reqbp)); 289 else 290 return (error); 291 } 292 293 /* 294 * If blocks are contiguous on disk, use this to provide clustered 295 * read ahead. We will read as many blocks as possible sequentially 296 * and then parcel them up into logical blocks in the buffer hash table. 297 */ 298 static struct buf * 299 cluster_rbuild(struct vnode *vp, u_quad_t filesize, daddr_t lbn, 300 daddr_t blkno, long size, int run, struct buf *fbp) 301 { 302 struct buf *bp, *tbp; 303 daddr_t bn; 304 int i, inc, j; 305 306 KASSERT(size == vp->v_mount->mnt_stat.f_iosize, 307 ("cluster_rbuild: size %ld != filesize %ld\n", 308 size, vp->v_mount->mnt_stat.f_iosize)); 309 310 /* 311 * avoid a division 312 */ 313 while ((u_quad_t) size * (lbn + run) > filesize) { 314 --run; 315 } 316 317 if (fbp) { 318 tbp = fbp; 319 tbp->b_flags |= B_READ; 320 } else { 321 tbp = getblk(vp, lbn, size, 0, 0); 322 if (tbp->b_flags & B_CACHE) 323 return tbp; 324 tbp->b_flags |= B_ASYNC | B_READ | B_RAM; 325 } 326 327 tbp->b_blkno = blkno; 328 if( (tbp->b_flags & B_MALLOC) || 329 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1) ) 330 return tbp; 331 332 bp = trypbuf(&cluster_pbuf_freecnt); 333 if (bp == 0) 334 return tbp; 335 336 /* 337 * We are synthesizing a buffer out of vm_page_t's, but 338 * if the block size is not page aligned then the starting 339 * address may not be either. Inherit the b_data offset 340 * from the original buffer. 341 */ 342 bp->b_data = (char *)((vm_offset_t)bp->b_data | 343 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 344 bp->b_flags = B_ASYNC | B_READ | B_CALL | B_CLUSTER | B_VMIO; 345 bp->b_iodone = cluster_callback; 346 bp->b_blkno = blkno; 347 bp->b_lblkno = lbn; 348 bp->b_offset = tbp->b_offset; 349 KASSERT(bp->b_offset != NOOFFSET, ("cluster_rbuild: no buffer offset")); 350 pbgetvp(vp, bp); 351 352 TAILQ_INIT(&bp->b_cluster.cluster_head); 353 354 bp->b_bcount = 0; 355 bp->b_bufsize = 0; 356 bp->b_xio.xio_npages = 0; 357 358 inc = btodb(size); 359 for (bn = blkno, i = 0; i < run; ++i, bn += inc) { 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 = incore(vp, lbn + i)) != 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, lbn + i, 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 ((fbp && (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_blkno == tbp->b_lblkno) { 432 tbp->b_blkno = bn; 433 } else if (tbp->b_blkno != bn) { 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 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head, 444 tbp, b_cluster.cluster_entry); 445 for (j = 0; j < tbp->b_xio.xio_npages; j += 1) { 446 vm_page_t m; 447 m = tbp->b_xio.xio_pages[j]; 448 vm_page_io_start(m); 449 vm_object_pip_add(m->object, 1); 450 if ((bp->b_xio.xio_npages == 0) || 451 (bp->b_xio.xio_pages[bp->b_xio.xio_npages-1] != m)) { 452 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 453 bp->b_xio.xio_npages++; 454 } 455 if ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) 456 tbp->b_xio.xio_pages[j] = bogus_page; 457 } 458 /* 459 * XXX shouldn't this be += size for both, like in 460 * cluster_wbuild()? 461 * 462 * Don't inherit tbp->b_bufsize as it may be larger due to 463 * a non-page-aligned size. Instead just aggregate using 464 * 'size'. 465 */ 466 if (tbp->b_bcount != size) 467 printf("warning: tbp->b_bcount wrong %ld vs %ld\n", tbp->b_bcount, size); 468 if (tbp->b_bufsize != size) 469 printf("warning: tbp->b_bufsize wrong %ld vs %ld\n", tbp->b_bufsize, size); 470 bp->b_bcount += size; 471 bp->b_bufsize += size; 472 } 473 474 /* 475 * Fully valid pages in the cluster are already good and do not need 476 * to be re-read from disk. Replace the page with bogus_page 477 */ 478 for (j = 0; j < bp->b_xio.xio_npages; j++) { 479 if ((bp->b_xio.xio_pages[j]->valid & VM_PAGE_BITS_ALL) == 480 VM_PAGE_BITS_ALL) { 481 bp->b_xio.xio_pages[j] = bogus_page; 482 } 483 } 484 if (bp->b_bufsize > bp->b_kvasize) 485 panic("cluster_rbuild: b_bufsize(%ld) > b_kvasize(%d)", 486 bp->b_bufsize, bp->b_kvasize); 487 bp->b_kvasize = bp->b_bufsize; 488 489 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 490 (vm_page_t *)bp->b_xio.xio_pages, bp->b_xio.xio_npages); 491 return (bp); 492 } 493 494 /* 495 * Cleanup after a clustered read or write. 496 * This is complicated by the fact that any of the buffers might have 497 * extra memory (if there were no empty buffer headers at allocbuf time) 498 * that we will need to shift around. 499 */ 500 void 501 cluster_callback(struct buf *bp) 502 { 503 struct buf *nbp, *tbp; 504 int error = 0; 505 506 /* 507 * Must propogate errors to all the components. 508 */ 509 if (bp->b_flags & B_ERROR) 510 error = bp->b_error; 511 512 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_xio.xio_npages); 513 /* 514 * Move memory from the large cluster buffer into the component 515 * buffers and mark IO as done on these. 516 */ 517 for (tbp = TAILQ_FIRST(&bp->b_cluster.cluster_head); 518 tbp; tbp = nbp) { 519 nbp = TAILQ_NEXT(&tbp->b_cluster, cluster_entry); 520 if (error) { 521 tbp->b_flags |= B_ERROR; 522 tbp->b_error = error; 523 } else { 524 tbp->b_dirtyoff = tbp->b_dirtyend = 0; 525 tbp->b_flags &= ~(B_ERROR|B_INVAL); 526 /* 527 * XXX the bdwrite()/bqrelse() issued during 528 * cluster building clears B_RELBUF (see bqrelse() 529 * comment). If direct I/O was specified, we have 530 * to restore it here to allow the buffer and VM 531 * to be freed. 532 */ 533 if (tbp->b_flags & B_DIRECT) 534 tbp->b_flags |= B_RELBUF; 535 } 536 biodone(tbp); 537 } 538 relpbuf(bp, &cluster_pbuf_freecnt); 539 } 540 541 /* 542 * cluster_wbuild_wb: 543 * 544 * Implement modified write build for cluster. 545 * 546 * write_behind = 0 write behind disabled 547 * write_behind = 1 write behind normal (default) 548 * write_behind = 2 write behind backed-off 549 */ 550 551 static __inline int 552 cluster_wbuild_wb(struct vnode *vp, long size, daddr_t start_lbn, int len) 553 { 554 int r = 0; 555 556 switch(write_behind) { 557 case 2: 558 if (start_lbn < len) 559 break; 560 start_lbn -= len; 561 /* fall through */ 562 case 1: 563 r = cluster_wbuild(vp, size, start_lbn, len); 564 /* fall through */ 565 default: 566 /* fall through */ 567 break; 568 } 569 return(r); 570 } 571 572 /* 573 * Do clustered write for FFS. 574 * 575 * Three cases: 576 * 1. Write is not sequential (write asynchronously) 577 * Write is sequential: 578 * 2. beginning of cluster - begin cluster 579 * 3. middle of a cluster - add to cluster 580 * 4. end of a cluster - asynchronously write cluster 581 */ 582 void 583 cluster_write(struct buf *bp, u_quad_t filesize, int seqcount) 584 { 585 struct vnode *vp; 586 daddr_t lbn; 587 int maxclen, cursize; 588 int lblocksize; 589 int async; 590 591 vp = bp->b_vp; 592 if (vp->v_type == VREG) { 593 async = vp->v_mount->mnt_flag & MNT_ASYNC; 594 lblocksize = vp->v_mount->mnt_stat.f_iosize; 595 } else { 596 async = 0; 597 lblocksize = bp->b_bufsize; 598 } 599 lbn = bp->b_lblkno; 600 KASSERT(bp->b_offset != NOOFFSET, ("cluster_write: no buffer offset")); 601 602 /* Initialize vnode to beginning of file. */ 603 if (lbn == 0) 604 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0; 605 606 if (vp->v_clen == 0 || lbn != vp->v_lastw + 1 || 607 (bp->b_blkno != vp->v_lasta + btodb(lblocksize))) { 608 maxclen = vp->v_mount->mnt_iosize_max / lblocksize - 1; 609 if (vp->v_clen != 0) { 610 /* 611 * Next block is not sequential. 612 * 613 * If we are not writing at end of file, the process 614 * seeked to another point in the file since its last 615 * write, or we have reached our maximum cluster size, 616 * then push the previous cluster. Otherwise try 617 * reallocating to make it sequential. 618 * 619 * Change to algorithm: only push previous cluster if 620 * it was sequential from the point of view of the 621 * seqcount heuristic, otherwise leave the buffer 622 * intact so we can potentially optimize the I/O 623 * later on in the buf_daemon or update daemon 624 * flush. 625 */ 626 cursize = vp->v_lastw - vp->v_cstart + 1; 627 if (((u_quad_t) bp->b_offset + lblocksize) != filesize || 628 lbn != vp->v_lastw + 1 || vp->v_clen <= cursize) { 629 if (!async && seqcount > 0) { 630 cluster_wbuild_wb(vp, lblocksize, 631 vp->v_cstart, cursize); 632 } 633 } else { 634 struct buf **bpp, **endbp; 635 struct cluster_save *buflist; 636 637 buflist = cluster_collectbufs(vp, bp); 638 endbp = &buflist->bs_children 639 [buflist->bs_nchildren - 1]; 640 if (VOP_REALLOCBLKS(vp, buflist)) { 641 /* 642 * Failed, push the previous cluster 643 * if *really* writing sequentially 644 * in the logical file (seqcount > 1), 645 * otherwise delay it in the hopes that 646 * the low level disk driver can 647 * optimize the write ordering. 648 */ 649 for (bpp = buflist->bs_children; 650 bpp < endbp; bpp++) 651 brelse(*bpp); 652 free(buflist, M_SEGMENT); 653 if (seqcount > 1) { 654 cluster_wbuild_wb(vp, 655 lblocksize, vp->v_cstart, 656 cursize); 657 } 658 } else { 659 /* 660 * Succeeded, keep building cluster. 661 */ 662 for (bpp = buflist->bs_children; 663 bpp <= endbp; bpp++) 664 bdwrite(*bpp); 665 free(buflist, M_SEGMENT); 666 vp->v_lastw = lbn; 667 vp->v_lasta = bp->b_blkno; 668 return; 669 } 670 } 671 } 672 /* 673 * Consider beginning a cluster. If at end of file, make 674 * cluster as large as possible, otherwise find size of 675 * existing cluster. 676 */ 677 if ((vp->v_type == VREG) && 678 ((u_quad_t) bp->b_offset + lblocksize) != filesize && 679 (bp->b_blkno == bp->b_lblkno) && 680 (VOP_BMAP(vp, lbn, NULL, &bp->b_blkno, &maxclen, NULL) || 681 bp->b_blkno == -1)) { 682 bawrite(bp); 683 vp->v_clen = 0; 684 vp->v_lasta = bp->b_blkno; 685 vp->v_cstart = lbn + 1; 686 vp->v_lastw = lbn; 687 return; 688 } 689 vp->v_clen = maxclen; 690 if (!async && maxclen == 0) { /* I/O not contiguous */ 691 vp->v_cstart = lbn + 1; 692 bawrite(bp); 693 } else { /* Wait for rest of cluster */ 694 vp->v_cstart = lbn; 695 bdwrite(bp); 696 } 697 } else if (lbn == vp->v_cstart + vp->v_clen) { 698 /* 699 * At end of cluster, write it out if seqcount tells us we 700 * are operating sequentially, otherwise let the buf or 701 * update daemon handle it. 702 */ 703 bdwrite(bp); 704 if (seqcount > 1) 705 cluster_wbuild_wb(vp, lblocksize, vp->v_cstart, vp->v_clen + 1); 706 vp->v_clen = 0; 707 vp->v_cstart = lbn + 1; 708 } else if (vm_page_count_severe()) { 709 /* 710 * We are low on memory, get it going NOW 711 */ 712 bawrite(bp); 713 } else { 714 /* 715 * In the middle of a cluster, so just delay the I/O for now. 716 */ 717 bdwrite(bp); 718 } 719 vp->v_lastw = lbn; 720 vp->v_lasta = bp->b_blkno; 721 } 722 723 724 /* 725 * This is an awful lot like cluster_rbuild...wish they could be combined. 726 * The last lbn argument is the current block on which I/O is being 727 * performed. Check to see that it doesn't fall in the middle of 728 * the current block (if last_bp == NULL). 729 */ 730 int 731 cluster_wbuild(struct vnode *vp, long size, daddr_t start_lbn, int len) 732 { 733 struct buf *bp, *tbp; 734 int i, j, s; 735 int totalwritten = 0; 736 int dbsize = btodb(size); 737 738 while (len > 0) { 739 s = splbio(); 740 /* 741 * If the buffer is not delayed-write (i.e. dirty), or it 742 * is delayed-write but either locked or inval, it cannot 743 * partake in the clustered write. 744 */ 745 if (((tbp = gbincore(vp, start_lbn)) == NULL) || 746 ((tbp->b_flags & (B_LOCKED | B_INVAL | B_DELWRI)) != B_DELWRI) || 747 BUF_LOCK(tbp, LK_EXCLUSIVE | LK_NOWAIT)) { 748 ++start_lbn; 749 --len; 750 splx(s); 751 continue; 752 } 753 bremfree(tbp); 754 tbp->b_flags &= ~B_DONE; 755 splx(s); 756 757 /* 758 * Extra memory in the buffer, punt on this buffer. 759 * XXX we could handle this in most cases, but we would 760 * have to push the extra memory down to after our max 761 * possible cluster size and then potentially pull it back 762 * up if the cluster was terminated prematurely--too much 763 * hassle. 764 */ 765 if (((tbp->b_flags & (B_CLUSTEROK|B_MALLOC)) != B_CLUSTEROK) || 766 (tbp->b_bcount != tbp->b_bufsize) || 767 (tbp->b_bcount != size) || 768 (len == 1) || 769 ((bp = getpbuf(&cluster_pbuf_freecnt)) == NULL)) { 770 totalwritten += tbp->b_bufsize; 771 bawrite(tbp); 772 ++start_lbn; 773 --len; 774 continue; 775 } 776 777 /* 778 * We got a pbuf to make the cluster in. 779 * so initialise it. 780 */ 781 TAILQ_INIT(&bp->b_cluster.cluster_head); 782 bp->b_bcount = 0; 783 bp->b_bufsize = 0; 784 bp->b_xio.xio_npages = 0; 785 bp->b_blkno = tbp->b_blkno; 786 bp->b_lblkno = tbp->b_lblkno; 787 bp->b_offset = tbp->b_offset; 788 789 /* 790 * We are synthesizing a buffer out of vm_page_t's, but 791 * if the block size is not page aligned then the starting 792 * address may not be either. Inherit the b_data offset 793 * from the original buffer. 794 */ 795 bp->b_data = (char *)((vm_offset_t)bp->b_data | 796 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 797 bp->b_flags |= B_CALL | B_CLUSTER | 798 (tbp->b_flags & (B_VMIO | B_NEEDCOMMIT | B_NOWDRAIN)); 799 bp->b_iodone = cluster_callback; 800 pbgetvp(vp, bp); 801 /* 802 * From this location in the file, scan forward to see 803 * if there are buffers with adjacent data that need to 804 * be written as well. 805 */ 806 for (i = 0; i < len; ++i, ++start_lbn) { 807 if (i != 0) { /* If not the first buffer */ 808 s = splbio(); 809 /* 810 * If the adjacent data is not even in core it 811 * can't need to be written. 812 */ 813 if ((tbp = gbincore(vp, start_lbn)) == NULL) { 814 splx(s); 815 break; 816 } 817 818 /* 819 * If it IS in core, but has different 820 * characteristics, or is locked (which 821 * means it could be undergoing a background 822 * I/O or be in a weird state), then don't 823 * cluster with it. 824 */ 825 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK | 826 B_INVAL | B_DELWRI | B_NEEDCOMMIT)) 827 != (B_DELWRI | B_CLUSTEROK | 828 (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) || 829 (tbp->b_flags & B_LOCKED) || 830 BUF_LOCK(tbp, LK_EXCLUSIVE | LK_NOWAIT)) { 831 splx(s); 832 break; 833 } 834 835 /* 836 * Check that the combined cluster 837 * would make sense with regard to pages 838 * and would not be too large 839 */ 840 if ((tbp->b_bcount != size) || 841 ((bp->b_blkno + (dbsize * i)) != 842 tbp->b_blkno) || 843 ((tbp->b_xio.xio_npages + bp->b_xio.xio_npages) > 844 (vp->v_mount->mnt_iosize_max / PAGE_SIZE))) { 845 BUF_UNLOCK(tbp); 846 splx(s); 847 break; 848 } 849 /* 850 * Ok, it's passed all the tests, 851 * so remove it from the free list 852 * and mark it busy. We will use it. 853 */ 854 bremfree(tbp); 855 tbp->b_flags &= ~B_DONE; 856 splx(s); 857 } /* end of code for non-first buffers only */ 858 /* check for latent dependencies to be handled */ 859 if ((LIST_FIRST(&tbp->b_dep)) != NULL && 860 bioops.io_start) 861 (*bioops.io_start)(tbp); 862 /* 863 * If the IO is via the VM then we do some 864 * special VM hackery (yuck). Since the buffer's 865 * block size may not be page-aligned it is possible 866 * for a page to be shared between two buffers. We 867 * have to get rid of the duplication when building 868 * the cluster. 869 */ 870 if (tbp->b_flags & B_VMIO) { 871 vm_page_t m; 872 873 if (i != 0) { /* if not first buffer */ 874 for (j = 0; j < tbp->b_xio.xio_npages; j += 1) { 875 m = tbp->b_xio.xio_pages[j]; 876 if (m->flags & PG_BUSY) { 877 bqrelse(tbp); 878 goto finishcluster; 879 } 880 } 881 } 882 883 for (j = 0; j < tbp->b_xio.xio_npages; j += 1) { 884 m = tbp->b_xio.xio_pages[j]; 885 vm_page_io_start(m); 886 vm_object_pip_add(m->object, 1); 887 if ((bp->b_xio.xio_npages == 0) || 888 (bp->b_xio.xio_pages[bp->b_xio.xio_npages - 1] != m)) { 889 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 890 bp->b_xio.xio_npages++; 891 } 892 } 893 } 894 bp->b_bcount += size; 895 bp->b_bufsize += size; 896 897 s = splbio(); 898 bundirty(tbp); 899 tbp->b_flags &= ~(B_READ | B_DONE | B_ERROR); 900 tbp->b_flags |= B_ASYNC; 901 reassignbuf(tbp, tbp->b_vp); /* put on clean list */ 902 ++tbp->b_vp->v_numoutput; 903 splx(s); 904 BUF_KERNPROC(tbp); 905 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head, 906 tbp, b_cluster.cluster_entry); 907 } 908 finishcluster: 909 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 910 (vm_page_t *) bp->b_xio.xio_pages, bp->b_xio.xio_npages); 911 if (bp->b_bufsize > bp->b_kvasize) 912 panic( 913 "cluster_wbuild: b_bufsize(%ld) > b_kvasize(%d)\n", 914 bp->b_bufsize, bp->b_kvasize); 915 bp->b_kvasize = bp->b_bufsize; 916 totalwritten += bp->b_bufsize; 917 bp->b_dirtyoff = 0; 918 bp->b_dirtyend = bp->b_bufsize; 919 bawrite(bp); 920 921 len -= i; 922 } 923 return totalwritten; 924 } 925 926 /* 927 * Collect together all the buffers in a cluster. 928 * Plus add one additional buffer. 929 */ 930 static struct cluster_save * 931 cluster_collectbufs(struct vnode *vp, struct buf *last_bp) 932 { 933 struct cluster_save *buflist; 934 struct buf *bp; 935 daddr_t lbn; 936 int i, len; 937 938 len = vp->v_lastw - vp->v_cstart + 1; 939 buflist = malloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist), 940 M_SEGMENT, M_WAITOK); 941 buflist->bs_nchildren = 0; 942 buflist->bs_children = (struct buf **) (buflist + 1); 943 for (lbn = vp->v_cstart, i = 0; i < len; lbn++, i++) { 944 (void) bread(vp, lbn, last_bp->b_bcount, &bp); 945 buflist->bs_children[i] = bp; 946 if (bp->b_blkno == bp->b_lblkno) 947 VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno, 948 NULL, NULL); 949 } 950 buflist->bs_children[i] = bp = last_bp; 951 if (bp->b_blkno == bp->b_lblkno) 952 VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno, 953 NULL, NULL); 954 buflist->bs_nchildren = i + 1; 955 return (buflist); 956 } 957