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 1.13 2005/06/06 15:02:28 dillon 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 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 struct buf *tbp; 131 bp->b_flags &= ~B_RAM; 132 /* 133 * We do the crit here so that there is no window 134 * between the incore and the b_usecount increment 135 * below. We opt to keep the crit out of the loop 136 * for efficiency. 137 */ 138 crit_enter(); 139 for (i = 1; i < maxra; i++) { 140 141 if (!(tbp = incore(vp, lblkno+i))) { 142 break; 143 } 144 145 /* 146 * Set another read-ahead mark so we know 147 * to check again. 148 */ 149 if (((i % racluster) == (racluster - 1)) || 150 (i == (maxra - 1))) 151 tbp->b_flags |= B_RAM; 152 } 153 crit_exit(); 154 if (i >= maxra) { 155 return 0; 156 } 157 lblkno += i; 158 } 159 reqbp = bp = NULL; 160 } else { 161 off_t firstread = bp->b_offset; 162 163 KASSERT(bp->b_offset != NOOFFSET, 164 ("cluster_read: no buffer offset")); 165 if (firstread + totread > filesize) 166 totread = filesize - firstread; 167 if (totread > size) { 168 int nblks = 0; 169 int ncontigafter; 170 while (totread > 0) { 171 nblks++; 172 totread -= size; 173 } 174 if (nblks == 1) 175 goto single_block_read; 176 if (nblks > racluster) 177 nblks = racluster; 178 179 error = VOP_BMAP(vp, lblkno, NULL, 180 &blkno, &ncontigafter, NULL); 181 if (error) 182 goto single_block_read; 183 if (blkno == -1) 184 goto single_block_read; 185 if (ncontigafter == 0) 186 goto single_block_read; 187 if (ncontigafter + 1 < nblks) 188 nblks = ncontigafter + 1; 189 190 bp = cluster_rbuild(vp, filesize, lblkno, 191 blkno, size, nblks, bp); 192 lblkno += (bp->b_bufsize / size); 193 } else { 194 single_block_read: 195 /* 196 * if it isn't in the cache, then get a chunk from 197 * disk if sequential, otherwise just get the block. 198 */ 199 bp->b_flags |= B_READ | B_RAM; 200 lblkno += 1; 201 } 202 } 203 204 /* 205 * if we have been doing sequential I/O, then do some read-ahead 206 */ 207 rbp = NULL; 208 if (seqcount && (lblkno < (origblkno + seqcount))) { 209 /* 210 * we now build the read-ahead buffer if it is desirable. 211 */ 212 if (((u_quad_t)(lblkno + 1) * size) <= filesize && 213 !(error = VOP_BMAP(vp, lblkno, NULL, &blkno, &num_ra, NULL)) && 214 blkno != -1) { 215 int nblksread; 216 int ntoread = num_ra + 1; 217 nblksread = (origtotread + size - 1) / size; 218 if (seqcount < nblksread) 219 seqcount = nblksread; 220 if (seqcount < ntoread) 221 ntoread = seqcount; 222 if (num_ra) { 223 rbp = cluster_rbuild(vp, filesize, lblkno, 224 blkno, size, ntoread, NULL); 225 } else { 226 rbp = getblk(vp, lblkno, size, 0, 0); 227 rbp->b_flags |= B_READ | B_ASYNC | B_RAM; 228 rbp->b_blkno = blkno; 229 } 230 } 231 } 232 233 /* 234 * handle the synchronous read 235 */ 236 if (bp) { 237 #if defined(CLUSTERDEBUG) 238 if (rcluster) 239 printf("S(%ld,%ld,%d) ", 240 (long)bp->b_lblkno, bp->b_bcount, seqcount); 241 #endif 242 if ((bp->b_flags & B_CLUSTER) == 0) { 243 vfs_busy_pages(bp, 0); 244 } 245 bp->b_flags &= ~(B_ERROR|B_INVAL); 246 if (bp->b_flags & (B_ASYNC|B_CALL)) 247 BUF_KERNPROC(bp); 248 error = VOP_STRATEGY(vp, bp); 249 } 250 251 /* 252 * and if we have read-aheads, do them too 253 */ 254 if (rbp) { 255 if (error) { 256 rbp->b_flags &= ~(B_ASYNC | B_READ); 257 brelse(rbp); 258 } else if (rbp->b_flags & B_CACHE) { 259 rbp->b_flags &= ~(B_ASYNC | B_READ); 260 bqrelse(rbp); 261 } else { 262 #if defined(CLUSTERDEBUG) 263 if (rcluster) { 264 if (bp) 265 printf("A+(%ld,%ld,%ld,%d) ", 266 (long)rbp->b_lblkno, rbp->b_bcount, 267 (long)(rbp->b_lblkno - origblkno), 268 seqcount); 269 else 270 printf("A(%ld,%ld,%ld,%d) ", 271 (long)rbp->b_lblkno, rbp->b_bcount, 272 (long)(rbp->b_lblkno - origblkno), 273 seqcount); 274 } 275 #endif 276 277 if ((rbp->b_flags & B_CLUSTER) == 0) { 278 vfs_busy_pages(rbp, 0); 279 } 280 rbp->b_flags &= ~(B_ERROR|B_INVAL); 281 if (rbp->b_flags & (B_ASYNC|B_CALL)) 282 BUF_KERNPROC(rbp); 283 (void) VOP_STRATEGY(vp, rbp); 284 } 285 } 286 if (reqbp) 287 return (biowait(reqbp)); 288 else 289 return (error); 290 } 291 292 /* 293 * If blocks are contiguous on disk, use this to provide clustered 294 * read ahead. We will read as many blocks as possible sequentially 295 * and then parcel them up into logical blocks in the buffer hash table. 296 */ 297 static struct buf * 298 cluster_rbuild(struct vnode *vp, u_quad_t filesize, daddr_t lbn, 299 daddr_t blkno, long size, int run, struct buf *fbp) 300 { 301 struct buf *bp, *tbp; 302 daddr_t bn; 303 int i, inc, j; 304 305 KASSERT(size == vp->v_mount->mnt_stat.f_iosize, 306 ("cluster_rbuild: size %ld != filesize %ld\n", 307 size, vp->v_mount->mnt_stat.f_iosize)); 308 309 /* 310 * avoid a division 311 */ 312 while ((u_quad_t) size * (lbn + run) > filesize) { 313 --run; 314 } 315 316 if (fbp) { 317 tbp = fbp; 318 tbp->b_flags |= B_READ; 319 } else { 320 tbp = getblk(vp, lbn, size, 0, 0); 321 if (tbp->b_flags & B_CACHE) 322 return tbp; 323 tbp->b_flags |= B_ASYNC | B_READ | B_RAM; 324 } 325 326 tbp->b_blkno = blkno; 327 if( (tbp->b_flags & B_MALLOC) || 328 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1) ) 329 return tbp; 330 331 bp = trypbuf(&cluster_pbuf_freecnt); 332 if (bp == 0) 333 return tbp; 334 335 /* 336 * We are synthesizing a buffer out of vm_page_t's, but 337 * if the block size is not page aligned then the starting 338 * address may not be either. Inherit the b_data offset 339 * from the original buffer. 340 */ 341 bp->b_data = (char *)((vm_offset_t)bp->b_data | 342 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 343 bp->b_flags = B_ASYNC | B_READ | B_CALL | B_CLUSTER | B_VMIO; 344 bp->b_iodone = cluster_callback; 345 bp->b_blkno = blkno; 346 bp->b_lblkno = lbn; 347 bp->b_offset = tbp->b_offset; 348 KASSERT(bp->b_offset != NOOFFSET, ("cluster_rbuild: no buffer offset")); 349 pbgetvp(vp, bp); 350 351 TAILQ_INIT(&bp->b_cluster.cluster_head); 352 353 bp->b_bcount = 0; 354 bp->b_bufsize = 0; 355 bp->b_xio.xio_npages = 0; 356 357 inc = btodb(size); 358 for (bn = blkno, i = 0; i < run; ++i, bn += inc) { 359 if (i != 0) { 360 if ((bp->b_xio.xio_npages * PAGE_SIZE) + 361 round_page(size) > vp->v_mount->mnt_iosize_max) { 362 break; 363 } 364 365 /* 366 * Shortcut some checks and try to avoid buffers that 367 * would block in the lock. The same checks have to 368 * be made again after we officially get the buffer. 369 */ 370 if ((tbp = incore(vp, lbn + i)) != NULL) { 371 if (BUF_LOCK(tbp, LK_EXCLUSIVE | LK_NOWAIT)) 372 break; 373 BUF_UNLOCK(tbp); 374 375 for (j = 0; j < tbp->b_xio.xio_npages; j++) { 376 if (tbp->b_xio.xio_pages[j]->valid) 377 break; 378 } 379 380 if (j != tbp->b_xio.xio_npages) 381 break; 382 383 if (tbp->b_bcount != size) 384 break; 385 } 386 387 tbp = getblk(vp, lbn + i, size, 0, 0); 388 389 /* 390 * Stop scanning if the buffer is fuly valid 391 * (marked B_CACHE), or locked (may be doing a 392 * background write), or if the buffer is not 393 * VMIO backed. The clustering code can only deal 394 * with VMIO-backed buffers. 395 */ 396 if ((tbp->b_flags & (B_CACHE|B_LOCKED)) || 397 (tbp->b_flags & B_VMIO) == 0) { 398 bqrelse(tbp); 399 break; 400 } 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 for (j = 0;j < tbp->b_xio.xio_npages; j++) { 408 if (tbp->b_xio.xio_pages[j]->valid) 409 break; 410 } 411 if (j != tbp->b_xio.xio_npages) { 412 bqrelse(tbp); 413 break; 414 } 415 416 /* 417 * Set a read-ahead mark as appropriate 418 */ 419 if ((fbp && (i == 1)) || (i == (run - 1))) 420 tbp->b_flags |= B_RAM; 421 422 /* 423 * Set the buffer up for an async read (XXX should 424 * we do this only if we do not wind up brelse()ing?). 425 * Set the block number if it isn't set, otherwise 426 * if it is make sure it matches the block number we 427 * expect. 428 */ 429 tbp->b_flags |= B_READ | B_ASYNC; 430 if (tbp->b_blkno == tbp->b_lblkno) { 431 tbp->b_blkno = bn; 432 } else if (tbp->b_blkno != bn) { 433 brelse(tbp); 434 break; 435 } 436 } 437 /* 438 * XXX fbp from caller may not be B_ASYNC, but we are going 439 * to biodone() it in cluster_callback() anyway 440 */ 441 BUF_KERNPROC(tbp); 442 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head, 443 tbp, b_cluster.cluster_entry); 444 for (j = 0; j < tbp->b_xio.xio_npages; j += 1) { 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 %ld vs %ld\n", tbp->b_bcount, size); 467 if (tbp->b_bufsize != size) 468 printf("warning: tbp->b_bufsize wrong %ld vs %ld\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(%ld) > 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 void 500 cluster_callback(struct buf *bp) 501 { 502 struct buf *nbp, *tbp; 503 int error = 0; 504 505 /* 506 * Must propogate errors to all the components. 507 */ 508 if (bp->b_flags & B_ERROR) 509 error = bp->b_error; 510 511 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_xio.xio_npages); 512 /* 513 * Move memory from the large cluster buffer into the component 514 * buffers and mark IO as done on these. 515 */ 516 for (tbp = TAILQ_FIRST(&bp->b_cluster.cluster_head); 517 tbp; tbp = nbp) { 518 nbp = TAILQ_NEXT(&tbp->b_cluster, cluster_entry); 519 if (error) { 520 tbp->b_flags |= B_ERROR; 521 tbp->b_error = error; 522 } else { 523 tbp->b_dirtyoff = tbp->b_dirtyend = 0; 524 tbp->b_flags &= ~(B_ERROR|B_INVAL); 525 /* 526 * XXX the bdwrite()/bqrelse() issued during 527 * cluster building clears B_RELBUF (see bqrelse() 528 * comment). If direct I/O was specified, we have 529 * to restore it here to allow the buffer and VM 530 * to be freed. 531 */ 532 if (tbp->b_flags & B_DIRECT) 533 tbp->b_flags |= B_RELBUF; 534 } 535 biodone(tbp); 536 } 537 relpbuf(bp, &cluster_pbuf_freecnt); 538 } 539 540 /* 541 * cluster_wbuild_wb: 542 * 543 * Implement modified write build for cluster. 544 * 545 * write_behind = 0 write behind disabled 546 * write_behind = 1 write behind normal (default) 547 * write_behind = 2 write behind backed-off 548 */ 549 550 static __inline int 551 cluster_wbuild_wb(struct vnode *vp, long size, daddr_t start_lbn, int len) 552 { 553 int r = 0; 554 555 switch(write_behind) { 556 case 2: 557 if (start_lbn < len) 558 break; 559 start_lbn -= len; 560 /* fall through */ 561 case 1: 562 r = cluster_wbuild(vp, size, start_lbn, len); 563 /* fall through */ 564 default: 565 /* fall through */ 566 break; 567 } 568 return(r); 569 } 570 571 /* 572 * Do clustered write for FFS. 573 * 574 * Three cases: 575 * 1. Write is not sequential (write asynchronously) 576 * Write is sequential: 577 * 2. beginning of cluster - begin cluster 578 * 3. middle of a cluster - add to cluster 579 * 4. end of a cluster - asynchronously write cluster 580 */ 581 void 582 cluster_write(struct buf *bp, u_quad_t filesize, int seqcount) 583 { 584 struct vnode *vp; 585 daddr_t lbn; 586 int maxclen, cursize; 587 int lblocksize; 588 int async; 589 590 vp = bp->b_vp; 591 if (vp->v_type == VREG) { 592 async = vp->v_mount->mnt_flag & MNT_ASYNC; 593 lblocksize = vp->v_mount->mnt_stat.f_iosize; 594 } else { 595 async = 0; 596 lblocksize = bp->b_bufsize; 597 } 598 lbn = bp->b_lblkno; 599 KASSERT(bp->b_offset != NOOFFSET, ("cluster_write: no buffer offset")); 600 601 /* Initialize vnode to beginning of file. */ 602 if (lbn == 0) 603 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0; 604 605 if (vp->v_clen == 0 || lbn != vp->v_lastw + 1 || 606 (bp->b_blkno != vp->v_lasta + btodb(lblocksize))) { 607 maxclen = vp->v_mount->mnt_iosize_max / lblocksize - 1; 608 if (vp->v_clen != 0) { 609 /* 610 * Next block is not sequential. 611 * 612 * If we are not writing at end of file, the process 613 * seeked to another point in the file since its last 614 * write, or we have reached our maximum cluster size, 615 * then push the previous cluster. Otherwise try 616 * reallocating to make it sequential. 617 * 618 * Change to algorithm: only push previous cluster if 619 * it was sequential from the point of view of the 620 * seqcount heuristic, otherwise leave the buffer 621 * intact so we can potentially optimize the I/O 622 * later on in the buf_daemon or update daemon 623 * flush. 624 */ 625 cursize = vp->v_lastw - vp->v_cstart + 1; 626 if (((u_quad_t) bp->b_offset + lblocksize) != filesize || 627 lbn != vp->v_lastw + 1 || vp->v_clen <= cursize) { 628 if (!async && seqcount > 0) { 629 cluster_wbuild_wb(vp, lblocksize, 630 vp->v_cstart, cursize); 631 } 632 } else { 633 struct buf **bpp, **endbp; 634 struct cluster_save *buflist; 635 636 buflist = cluster_collectbufs(vp, bp); 637 endbp = &buflist->bs_children 638 [buflist->bs_nchildren - 1]; 639 if (VOP_REALLOCBLKS(vp, buflist)) { 640 /* 641 * Failed, push the previous cluster 642 * if *really* writing sequentially 643 * in the logical file (seqcount > 1), 644 * otherwise delay it in the hopes that 645 * the low level disk driver can 646 * optimize the write ordering. 647 */ 648 for (bpp = buflist->bs_children; 649 bpp < endbp; bpp++) 650 brelse(*bpp); 651 free(buflist, M_SEGMENT); 652 if (seqcount > 1) { 653 cluster_wbuild_wb(vp, 654 lblocksize, vp->v_cstart, 655 cursize); 656 } 657 } else { 658 /* 659 * Succeeded, keep building cluster. 660 */ 661 for (bpp = buflist->bs_children; 662 bpp <= endbp; bpp++) 663 bdwrite(*bpp); 664 free(buflist, M_SEGMENT); 665 vp->v_lastw = lbn; 666 vp->v_lasta = bp->b_blkno; 667 return; 668 } 669 } 670 } 671 /* 672 * Consider beginning a cluster. If at end of file, make 673 * cluster as large as possible, otherwise find size of 674 * existing cluster. 675 */ 676 if ((vp->v_type == VREG) && 677 ((u_quad_t) bp->b_offset + lblocksize) != filesize && 678 (bp->b_blkno == bp->b_lblkno) && 679 (VOP_BMAP(vp, lbn, NULL, &bp->b_blkno, &maxclen, NULL) || 680 bp->b_blkno == -1)) { 681 bawrite(bp); 682 vp->v_clen = 0; 683 vp->v_lasta = bp->b_blkno; 684 vp->v_cstart = lbn + 1; 685 vp->v_lastw = lbn; 686 return; 687 } 688 vp->v_clen = maxclen; 689 if (!async && maxclen == 0) { /* I/O not contiguous */ 690 vp->v_cstart = lbn + 1; 691 bawrite(bp); 692 } else { /* Wait for rest of cluster */ 693 vp->v_cstart = lbn; 694 bdwrite(bp); 695 } 696 } else if (lbn == vp->v_cstart + vp->v_clen) { 697 /* 698 * At end of cluster, write it out if seqcount tells us we 699 * are operating sequentially, otherwise let the buf or 700 * update daemon handle it. 701 */ 702 bdwrite(bp); 703 if (seqcount > 1) 704 cluster_wbuild_wb(vp, lblocksize, vp->v_cstart, vp->v_clen + 1); 705 vp->v_clen = 0; 706 vp->v_cstart = lbn + 1; 707 } else if (vm_page_count_severe()) { 708 /* 709 * We are low on memory, get it going NOW 710 */ 711 bawrite(bp); 712 } else { 713 /* 714 * In the middle of a cluster, so just delay the I/O for now. 715 */ 716 bdwrite(bp); 717 } 718 vp->v_lastw = lbn; 719 vp->v_lasta = bp->b_blkno; 720 } 721 722 723 /* 724 * This is an awful lot like cluster_rbuild...wish they could be combined. 725 * The last lbn argument is the current block on which I/O is being 726 * performed. Check to see that it doesn't fall in the middle of 727 * the current block (if last_bp == NULL). 728 */ 729 int 730 cluster_wbuild(struct vnode *vp, long size, daddr_t start_lbn, int len) 731 { 732 struct buf *bp, *tbp; 733 int i, j; 734 int totalwritten = 0; 735 int dbsize = btodb(size); 736 737 while (len > 0) { 738 crit_enter(); 739 /* 740 * If the buffer is not delayed-write (i.e. dirty), or it 741 * is delayed-write but either locked or inval, it cannot 742 * partake in the clustered write. 743 */ 744 if (((tbp = gbincore(vp, start_lbn)) == NULL) || 745 ((tbp->b_flags & (B_LOCKED | B_INVAL | B_DELWRI)) != B_DELWRI) || 746 BUF_LOCK(tbp, LK_EXCLUSIVE | LK_NOWAIT)) { 747 ++start_lbn; 748 --len; 749 crit_exit(); 750 continue; 751 } 752 bremfree(tbp); 753 tbp->b_flags &= ~B_DONE; 754 crit_exit(); 755 756 /* 757 * Extra memory in the buffer, punt on this buffer. 758 * XXX we could handle this in most cases, but we would 759 * have to push the extra memory down to after our max 760 * possible cluster size and then potentially pull it back 761 * up if the cluster was terminated prematurely--too much 762 * hassle. 763 */ 764 if (((tbp->b_flags & (B_CLUSTEROK|B_MALLOC)) != B_CLUSTEROK) || 765 (tbp->b_bcount != tbp->b_bufsize) || 766 (tbp->b_bcount != size) || 767 (len == 1) || 768 ((bp = getpbuf(&cluster_pbuf_freecnt)) == NULL)) { 769 totalwritten += tbp->b_bufsize; 770 bawrite(tbp); 771 ++start_lbn; 772 --len; 773 continue; 774 } 775 776 /* 777 * We got a pbuf to make the cluster in. 778 * so initialise it. 779 */ 780 TAILQ_INIT(&bp->b_cluster.cluster_head); 781 bp->b_bcount = 0; 782 bp->b_bufsize = 0; 783 bp->b_xio.xio_npages = 0; 784 bp->b_blkno = tbp->b_blkno; 785 bp->b_lblkno = tbp->b_lblkno; 786 bp->b_offset = tbp->b_offset; 787 788 /* 789 * We are synthesizing a buffer out of vm_page_t's, but 790 * if the block size is not page aligned then the starting 791 * address may not be either. Inherit the b_data offset 792 * from the original buffer. 793 */ 794 bp->b_data = (char *)((vm_offset_t)bp->b_data | 795 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 796 bp->b_flags |= B_CALL | B_CLUSTER | 797 (tbp->b_flags & (B_VMIO | B_NEEDCOMMIT | B_NOWDRAIN)); 798 bp->b_iodone = cluster_callback; 799 pbgetvp(vp, bp); 800 /* 801 * From this location in the file, scan forward to see 802 * if there are buffers with adjacent data that need to 803 * be written as well. 804 */ 805 for (i = 0; i < len; ++i, ++start_lbn) { 806 if (i != 0) { /* If not the first buffer */ 807 crit_enter(); 808 /* 809 * If the adjacent data is not even in core it 810 * can't need to be written. 811 */ 812 if ((tbp = gbincore(vp, start_lbn)) == NULL) { 813 crit_exit(); 814 break; 815 } 816 817 /* 818 * If it IS in core, but has different 819 * characteristics, or is locked (which 820 * means it could be undergoing a background 821 * I/O or be in a weird state), then don't 822 * cluster with it. 823 */ 824 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK | 825 B_INVAL | B_DELWRI | B_NEEDCOMMIT)) 826 != (B_DELWRI | B_CLUSTEROK | 827 (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) || 828 (tbp->b_flags & B_LOCKED) || 829 BUF_LOCK(tbp, LK_EXCLUSIVE | LK_NOWAIT)) { 830 crit_exit(); 831 break; 832 } 833 834 /* 835 * Check that the combined cluster 836 * would make sense with regard to pages 837 * and would not be too large 838 */ 839 if ((tbp->b_bcount != size) || 840 ((bp->b_blkno + (dbsize * i)) != 841 tbp->b_blkno) || 842 ((tbp->b_xio.xio_npages + bp->b_xio.xio_npages) > 843 (vp->v_mount->mnt_iosize_max / PAGE_SIZE))) { 844 BUF_UNLOCK(tbp); 845 crit_exit(); 846 break; 847 } 848 /* 849 * Ok, it's passed all the tests, 850 * so remove it from the free list 851 * and mark it busy. We will use it. 852 */ 853 bremfree(tbp); 854 tbp->b_flags &= ~B_DONE; 855 crit_exit(); 856 } /* end of code for non-first buffers only */ 857 /* check for latent dependencies to be handled */ 858 if ((LIST_FIRST(&tbp->b_dep)) != NULL && 859 bioops.io_start) 860 (*bioops.io_start)(tbp); 861 /* 862 * If the IO is via the VM then we do some 863 * special VM hackery (yuck). Since the buffer's 864 * block size may not be page-aligned it is possible 865 * for a page to be shared between two buffers. We 866 * have to get rid of the duplication when building 867 * the cluster. 868 */ 869 if (tbp->b_flags & B_VMIO) { 870 vm_page_t m; 871 872 if (i != 0) { /* if not first buffer */ 873 for (j = 0; j < tbp->b_xio.xio_npages; j += 1) { 874 m = tbp->b_xio.xio_pages[j]; 875 if (m->flags & PG_BUSY) { 876 bqrelse(tbp); 877 goto finishcluster; 878 } 879 } 880 } 881 882 for (j = 0; j < tbp->b_xio.xio_npages; j += 1) { 883 m = tbp->b_xio.xio_pages[j]; 884 vm_page_io_start(m); 885 vm_object_pip_add(m->object, 1); 886 if ((bp->b_xio.xio_npages == 0) || 887 (bp->b_xio.xio_pages[bp->b_xio.xio_npages - 1] != m)) { 888 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 889 bp->b_xio.xio_npages++; 890 } 891 } 892 } 893 bp->b_bcount += size; 894 bp->b_bufsize += size; 895 896 crit_enter(); 897 bundirty(tbp); 898 tbp->b_flags &= ~(B_READ | B_DONE | B_ERROR); 899 tbp->b_flags |= B_ASYNC; 900 reassignbuf(tbp, tbp->b_vp); /* put on clean list */ 901 ++tbp->b_vp->v_numoutput; 902 crit_exit(); 903 BUF_KERNPROC(tbp); 904 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head, 905 tbp, b_cluster.cluster_entry); 906 } 907 finishcluster: 908 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 909 (vm_page_t *) bp->b_xio.xio_pages, bp->b_xio.xio_npages); 910 if (bp->b_bufsize > bp->b_kvasize) 911 panic( 912 "cluster_wbuild: b_bufsize(%ld) > b_kvasize(%d)\n", 913 bp->b_bufsize, bp->b_kvasize); 914 bp->b_kvasize = bp->b_bufsize; 915 totalwritten += bp->b_bufsize; 916 bp->b_dirtyoff = 0; 917 bp->b_dirtyend = bp->b_bufsize; 918 bawrite(bp); 919 920 len -= i; 921 } 922 return totalwritten; 923 } 924 925 /* 926 * Collect together all the buffers in a cluster. 927 * Plus add one additional buffer. 928 */ 929 static struct cluster_save * 930 cluster_collectbufs(struct vnode *vp, struct buf *last_bp) 931 { 932 struct cluster_save *buflist; 933 struct buf *bp; 934 daddr_t lbn; 935 int i, len; 936 937 len = vp->v_lastw - vp->v_cstart + 1; 938 buflist = malloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist), 939 M_SEGMENT, M_WAITOK); 940 buflist->bs_nchildren = 0; 941 buflist->bs_children = (struct buf **) (buflist + 1); 942 for (lbn = vp->v_cstart, i = 0; i < len; lbn++, i++) { 943 (void) bread(vp, lbn, last_bp->b_bcount, &bp); 944 buflist->bs_children[i] = bp; 945 if (bp->b_blkno == bp->b_lblkno) 946 VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno, 947 NULL, NULL); 948 } 949 buflist->bs_children[i] = bp = last_bp; 950 if (bp->b_blkno == bp->b_lblkno) 951 VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno, 952 NULL, NULL); 953 buflist->bs_nchildren = i + 1; 954 return (buflist); 955 } 956