1 /*- 2 * Copyright (c) 1993 3 * The Regents of the University of California. All rights reserved. 4 * Modifications/enhancements: 5 * Copyright (c) 1995 John S. Dyson. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 4. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 * 31 * @(#)vfs_cluster.c 8.7 (Berkeley) 2/13/94 32 */ 33 34 #include <sys/cdefs.h> 35 __FBSDID("$FreeBSD$"); 36 37 #include "opt_debug_cluster.h" 38 39 #include <sys/param.h> 40 #include <sys/systm.h> 41 #include <sys/kernel.h> 42 #include <sys/proc.h> 43 #include <sys/bio.h> 44 #include <sys/buf.h> 45 #include <sys/vnode.h> 46 #include <sys/malloc.h> 47 #include <sys/mount.h> 48 #include <sys/resourcevar.h> 49 #include <sys/rwlock.h> 50 #include <sys/vmmeter.h> 51 #include <vm/vm.h> 52 #include <vm/vm_object.h> 53 #include <vm/vm_page.h> 54 #include <sys/sysctl.h> 55 56 #if defined(CLUSTERDEBUG) 57 static int rcluster= 0; 58 SYSCTL_INT(_debug, OID_AUTO, rcluster, CTLFLAG_RW, &rcluster, 0, 59 "Debug VFS clustering code"); 60 #endif 61 62 static MALLOC_DEFINE(M_SEGMENT, "cl_savebuf", "cluster_save buffer"); 63 64 static struct cluster_save *cluster_collectbufs(struct vnode *vp, 65 struct buf *last_bp, int gbflags); 66 static struct buf *cluster_rbuild(struct vnode *vp, u_quad_t filesize, 67 daddr_t lbn, daddr_t blkno, long size, int run, int gbflags, 68 struct buf *fbp); 69 static void cluster_callback(struct buf *); 70 71 static int write_behind = 1; 72 SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0, 73 "Cluster write-behind; 0: disable, 1: enable, 2: backed off"); 74 75 static int read_max = 64; 76 SYSCTL_INT(_vfs, OID_AUTO, read_max, CTLFLAG_RW, &read_max, 0, 77 "Cluster read-ahead max block count"); 78 79 static int read_min = 1; 80 SYSCTL_INT(_vfs, OID_AUTO, read_min, CTLFLAG_RW, &read_min, 0, 81 "Cluster read min block count"); 82 83 /* Page expended to mark partially backed buffers */ 84 extern vm_page_t bogus_page; 85 86 /* 87 * Read data to a buf, including read-ahead if we find this to be beneficial. 88 * cluster_read replaces bread. 89 */ 90 int 91 cluster_read(struct vnode *vp, u_quad_t filesize, daddr_t lblkno, long size, 92 struct ucred *cred, long totread, int seqcount, int gbflags, 93 struct buf **bpp) 94 { 95 struct buf *bp, *rbp, *reqbp; 96 struct bufobj *bo; 97 daddr_t blkno, origblkno; 98 int maxra, racluster; 99 int error, ncontig; 100 int i; 101 102 error = 0; 103 bo = &vp->v_bufobj; 104 if (!unmapped_buf_allowed) 105 gbflags &= ~GB_UNMAPPED; 106 107 /* 108 * Try to limit the amount of read-ahead by a few 109 * ad-hoc parameters. This needs work!!! 110 */ 111 racluster = vp->v_mount->mnt_iosize_max / size; 112 maxra = seqcount; 113 maxra = min(read_max, maxra); 114 maxra = min(nbuf/8, maxra); 115 if (((u_quad_t)(lblkno + maxra + 1) * size) > filesize) 116 maxra = (filesize / size) - lblkno; 117 118 /* 119 * get the requested block 120 */ 121 *bpp = reqbp = bp = getblk(vp, lblkno, size, 0, 0, gbflags); 122 origblkno = lblkno; 123 124 /* 125 * if it is in the cache, then check to see if the reads have been 126 * sequential. If they have, then try some read-ahead, otherwise 127 * back-off on prospective read-aheads. 128 */ 129 if (bp->b_flags & B_CACHE) { 130 if (!seqcount) { 131 return 0; 132 } else if ((bp->b_flags & B_RAM) == 0) { 133 return 0; 134 } else { 135 bp->b_flags &= ~B_RAM; 136 BO_RLOCK(bo); 137 for (i = 1; i < maxra; i++) { 138 /* 139 * Stop if the buffer does not exist or it 140 * is invalid (about to go away?) 141 */ 142 rbp = gbincore(&vp->v_bufobj, lblkno+i); 143 if (rbp == NULL || (rbp->b_flags & B_INVAL)) 144 break; 145 146 /* 147 * Set another read-ahead mark so we know 148 * to check again. (If we can lock the 149 * buffer without waiting) 150 */ 151 if ((((i % racluster) == (racluster - 1)) || 152 (i == (maxra - 1))) 153 && (0 == BUF_LOCK(rbp, 154 LK_EXCLUSIVE | LK_NOWAIT, NULL))) { 155 rbp->b_flags |= B_RAM; 156 BUF_UNLOCK(rbp); 157 } 158 } 159 BO_RUNLOCK(bo); 160 if (i >= maxra) { 161 return 0; 162 } 163 lblkno += i; 164 } 165 reqbp = bp = NULL; 166 /* 167 * If it isn't in the cache, then get a chunk from 168 * disk if sequential, otherwise just get the block. 169 */ 170 } else { 171 off_t firstread = bp->b_offset; 172 int nblks; 173 long minread; 174 175 KASSERT(bp->b_offset != NOOFFSET, 176 ("cluster_read: no buffer offset")); 177 178 ncontig = 0; 179 180 /* 181 * Adjust totread if needed 182 */ 183 minread = read_min * size; 184 if (minread > totread) 185 totread = minread; 186 187 /* 188 * Compute the total number of blocks that we should read 189 * synchronously. 190 */ 191 if (firstread + totread > filesize) 192 totread = filesize - firstread; 193 nblks = howmany(totread, size); 194 if (nblks > racluster) 195 nblks = racluster; 196 197 /* 198 * Now compute the number of contiguous blocks. 199 */ 200 if (nblks > 1) { 201 error = VOP_BMAP(vp, lblkno, NULL, 202 &blkno, &ncontig, NULL); 203 /* 204 * If this failed to map just do the original block. 205 */ 206 if (error || blkno == -1) 207 ncontig = 0; 208 } 209 210 /* 211 * If we have contiguous data available do a cluster 212 * otherwise just read the requested block. 213 */ 214 if (ncontig) { 215 /* Account for our first block. */ 216 ncontig = min(ncontig + 1, nblks); 217 if (ncontig < nblks) 218 nblks = ncontig; 219 bp = cluster_rbuild(vp, filesize, lblkno, 220 blkno, size, nblks, gbflags, bp); 221 lblkno += (bp->b_bufsize / size); 222 } else { 223 bp->b_flags |= B_RAM; 224 bp->b_iocmd = BIO_READ; 225 lblkno += 1; 226 } 227 } 228 229 /* 230 * handle the synchronous read so that it is available ASAP. 231 */ 232 if (bp) { 233 if ((bp->b_flags & B_CLUSTER) == 0) { 234 vfs_busy_pages(bp, 0); 235 } 236 bp->b_flags &= ~B_INVAL; 237 bp->b_ioflags &= ~BIO_ERROR; 238 if ((bp->b_flags & B_ASYNC) || bp->b_iodone != NULL) 239 BUF_KERNPROC(bp); 240 bp->b_iooffset = dbtob(bp->b_blkno); 241 bstrategy(bp); 242 curthread->td_ru.ru_inblock++; 243 } 244 245 /* 246 * If we have been doing sequential I/O, then do some read-ahead. 247 */ 248 while (lblkno < (origblkno + maxra)) { 249 error = VOP_BMAP(vp, lblkno, NULL, &blkno, &ncontig, NULL); 250 if (error) 251 break; 252 253 if (blkno == -1) 254 break; 255 256 /* 257 * We could throttle ncontig here by maxra but we might as 258 * well read the data if it is contiguous. We're throttled 259 * by racluster anyway. 260 */ 261 if (ncontig) { 262 ncontig = min(ncontig + 1, racluster); 263 rbp = cluster_rbuild(vp, filesize, lblkno, blkno, 264 size, ncontig, gbflags, NULL); 265 lblkno += (rbp->b_bufsize / size); 266 if (rbp->b_flags & B_DELWRI) { 267 bqrelse(rbp); 268 continue; 269 } 270 } else { 271 rbp = getblk(vp, lblkno, size, 0, 0, gbflags); 272 lblkno += 1; 273 if (rbp->b_flags & B_DELWRI) { 274 bqrelse(rbp); 275 continue; 276 } 277 rbp->b_flags |= B_ASYNC | B_RAM; 278 rbp->b_iocmd = BIO_READ; 279 rbp->b_blkno = blkno; 280 } 281 if (rbp->b_flags & B_CACHE) { 282 rbp->b_flags &= ~B_ASYNC; 283 bqrelse(rbp); 284 continue; 285 } 286 if ((rbp->b_flags & B_CLUSTER) == 0) { 287 vfs_busy_pages(rbp, 0); 288 } 289 rbp->b_flags &= ~B_INVAL; 290 rbp->b_ioflags &= ~BIO_ERROR; 291 if ((rbp->b_flags & B_ASYNC) || rbp->b_iodone != NULL) 292 BUF_KERNPROC(rbp); 293 rbp->b_iooffset = dbtob(rbp->b_blkno); 294 bstrategy(rbp); 295 curthread->td_ru.ru_inblock++; 296 } 297 298 if (reqbp) 299 return (bufwait(reqbp)); 300 else 301 return (error); 302 } 303 304 /* 305 * If blocks are contiguous on disk, use this to provide clustered 306 * read ahead. We will read as many blocks as possible sequentially 307 * and then parcel them up into logical blocks in the buffer hash table. 308 */ 309 static struct buf * 310 cluster_rbuild(struct vnode *vp, u_quad_t filesize, daddr_t lbn, 311 daddr_t blkno, long size, int run, int gbflags, struct buf *fbp) 312 { 313 struct buf *bp, *tbp; 314 daddr_t bn; 315 off_t off; 316 long tinc, tsize; 317 int i, inc, j, k, toff; 318 319 KASSERT(size == vp->v_mount->mnt_stat.f_iosize, 320 ("cluster_rbuild: size %ld != f_iosize %jd\n", 321 size, (intmax_t)vp->v_mount->mnt_stat.f_iosize)); 322 323 /* 324 * avoid a division 325 */ 326 while ((u_quad_t) size * (lbn + run) > filesize) { 327 --run; 328 } 329 330 if (fbp) { 331 tbp = fbp; 332 tbp->b_iocmd = BIO_READ; 333 } else { 334 tbp = getblk(vp, lbn, size, 0, 0, gbflags); 335 if (tbp->b_flags & B_CACHE) 336 return tbp; 337 tbp->b_flags |= B_ASYNC | B_RAM; 338 tbp->b_iocmd = BIO_READ; 339 } 340 tbp->b_blkno = blkno; 341 if( (tbp->b_flags & B_MALLOC) || 342 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1) ) 343 return tbp; 344 345 bp = trypbuf(&cluster_pbuf_freecnt); 346 if (bp == 0) 347 return tbp; 348 349 /* 350 * We are synthesizing a buffer out of vm_page_t's, but 351 * if the block size is not page aligned then the starting 352 * address may not be either. Inherit the b_data offset 353 * from the original buffer. 354 */ 355 bp->b_flags = B_ASYNC | B_CLUSTER | B_VMIO; 356 if ((gbflags & GB_UNMAPPED) != 0) { 357 bp->b_data = unmapped_buf; 358 } else { 359 bp->b_data = (char *)((vm_offset_t)bp->b_data | 360 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 361 } 362 bp->b_iocmd = BIO_READ; 363 bp->b_iodone = cluster_callback; 364 bp->b_blkno = blkno; 365 bp->b_lblkno = lbn; 366 bp->b_offset = tbp->b_offset; 367 KASSERT(bp->b_offset != NOOFFSET, ("cluster_rbuild: no buffer offset")); 368 pbgetvp(vp, bp); 369 370 TAILQ_INIT(&bp->b_cluster.cluster_head); 371 372 bp->b_bcount = 0; 373 bp->b_bufsize = 0; 374 bp->b_npages = 0; 375 376 inc = btodb(size); 377 for (bn = blkno, i = 0; i < run; ++i, bn += inc) { 378 if (i == 0) { 379 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object); 380 vfs_drain_busy_pages(tbp); 381 vm_object_pip_add(tbp->b_bufobj->bo_object, 382 tbp->b_npages); 383 for (k = 0; k < tbp->b_npages; k++) 384 vm_page_sbusy(tbp->b_pages[k]); 385 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object); 386 } else { 387 if ((bp->b_npages * PAGE_SIZE) + 388 round_page(size) > vp->v_mount->mnt_iosize_max) { 389 break; 390 } 391 392 tbp = getblk(vp, lbn + i, size, 0, 0, GB_LOCK_NOWAIT | 393 (gbflags & GB_UNMAPPED)); 394 395 /* Don't wait around for locked bufs. */ 396 if (tbp == NULL) 397 break; 398 399 /* 400 * Stop scanning if the buffer is fully valid 401 * (marked B_CACHE), or locked (may be doing a 402 * background write), or if the buffer is not 403 * VMIO backed. The clustering code can only deal 404 * with VMIO-backed buffers. The bo lock is not 405 * required for the BKGRDINPROG check since it 406 * can not be set without the buf lock. 407 */ 408 if ((tbp->b_vflags & BV_BKGRDINPROG) || 409 (tbp->b_flags & B_CACHE) || 410 (tbp->b_flags & B_VMIO) == 0) { 411 bqrelse(tbp); 412 break; 413 } 414 415 /* 416 * The buffer must be completely invalid in order to 417 * take part in the cluster. If it is partially valid 418 * then we stop. 419 */ 420 off = tbp->b_offset; 421 tsize = size; 422 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object); 423 for (j = 0; tsize > 0; j++) { 424 toff = off & PAGE_MASK; 425 tinc = tsize; 426 if (toff + tinc > PAGE_SIZE) 427 tinc = PAGE_SIZE - toff; 428 VM_OBJECT_ASSERT_WLOCKED(tbp->b_pages[j]->object); 429 if ((tbp->b_pages[j]->valid & 430 vm_page_bits(toff, tinc)) != 0) 431 break; 432 if (vm_page_xbusied(tbp->b_pages[j])) 433 break; 434 vm_object_pip_add(tbp->b_bufobj->bo_object, 1); 435 vm_page_sbusy(tbp->b_pages[j]); 436 off += tinc; 437 tsize -= tinc; 438 } 439 if (tsize > 0) { 440 clean_sbusy: 441 vm_object_pip_add(tbp->b_bufobj->bo_object, -j); 442 for (k = 0; k < j; k++) 443 vm_page_sunbusy(tbp->b_pages[k]); 444 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object); 445 bqrelse(tbp); 446 break; 447 } 448 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object); 449 450 /* 451 * Set a read-ahead mark as appropriate 452 */ 453 if ((fbp && (i == 1)) || (i == (run - 1))) 454 tbp->b_flags |= B_RAM; 455 456 /* 457 * Set the buffer up for an async read (XXX should 458 * we do this only if we do not wind up brelse()ing?). 459 * Set the block number if it isn't set, otherwise 460 * if it is make sure it matches the block number we 461 * expect. 462 */ 463 tbp->b_flags |= B_ASYNC; 464 tbp->b_iocmd = BIO_READ; 465 if (tbp->b_blkno == tbp->b_lblkno) { 466 tbp->b_blkno = bn; 467 } else if (tbp->b_blkno != bn) { 468 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object); 469 goto clean_sbusy; 470 } 471 } 472 /* 473 * XXX fbp from caller may not be B_ASYNC, but we are going 474 * to biodone() it in cluster_callback() anyway 475 */ 476 BUF_KERNPROC(tbp); 477 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head, 478 tbp, b_cluster.cluster_entry); 479 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object); 480 for (j = 0; j < tbp->b_npages; j += 1) { 481 vm_page_t m; 482 m = tbp->b_pages[j]; 483 if ((bp->b_npages == 0) || 484 (bp->b_pages[bp->b_npages-1] != m)) { 485 bp->b_pages[bp->b_npages] = m; 486 bp->b_npages++; 487 } 488 if (m->valid == VM_PAGE_BITS_ALL) 489 tbp->b_pages[j] = bogus_page; 490 } 491 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object); 492 /* 493 * Don't inherit tbp->b_bufsize as it may be larger due to 494 * a non-page-aligned size. Instead just aggregate using 495 * 'size'. 496 */ 497 if (tbp->b_bcount != size) 498 printf("warning: tbp->b_bcount wrong %ld vs %ld\n", tbp->b_bcount, size); 499 if (tbp->b_bufsize != size) 500 printf("warning: tbp->b_bufsize wrong %ld vs %ld\n", tbp->b_bufsize, size); 501 bp->b_bcount += size; 502 bp->b_bufsize += size; 503 } 504 505 /* 506 * Fully valid pages in the cluster are already good and do not need 507 * to be re-read from disk. Replace the page with bogus_page 508 */ 509 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 510 for (j = 0; j < bp->b_npages; j++) { 511 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[j]->object); 512 if (bp->b_pages[j]->valid == VM_PAGE_BITS_ALL) 513 bp->b_pages[j] = bogus_page; 514 } 515 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 516 if (bp->b_bufsize > bp->b_kvasize) 517 panic("cluster_rbuild: b_bufsize(%ld) > b_kvasize(%d)\n", 518 bp->b_bufsize, bp->b_kvasize); 519 520 if (buf_mapped(bp)) { 521 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 522 (vm_page_t *)bp->b_pages, bp->b_npages); 523 } 524 return (bp); 525 } 526 527 /* 528 * Cleanup after a clustered read or write. 529 * This is complicated by the fact that any of the buffers might have 530 * extra memory (if there were no empty buffer headers at allocbuf time) 531 * that we will need to shift around. 532 */ 533 static void 534 cluster_callback(bp) 535 struct buf *bp; 536 { 537 struct buf *nbp, *tbp; 538 int error = 0; 539 540 /* 541 * Must propogate errors to all the components. 542 */ 543 if (bp->b_ioflags & BIO_ERROR) 544 error = bp->b_error; 545 546 if (buf_mapped(bp)) { 547 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), 548 bp->b_npages); 549 } 550 /* 551 * Move memory from the large cluster buffer into the component 552 * buffers and mark IO as done on these. 553 */ 554 for (tbp = TAILQ_FIRST(&bp->b_cluster.cluster_head); 555 tbp; tbp = nbp) { 556 nbp = TAILQ_NEXT(&tbp->b_cluster, cluster_entry); 557 if (error) { 558 tbp->b_ioflags |= BIO_ERROR; 559 tbp->b_error = error; 560 } else { 561 tbp->b_dirtyoff = tbp->b_dirtyend = 0; 562 tbp->b_flags &= ~B_INVAL; 563 tbp->b_ioflags &= ~BIO_ERROR; 564 /* 565 * XXX the bdwrite()/bqrelse() issued during 566 * cluster building clears B_RELBUF (see bqrelse() 567 * comment). If direct I/O was specified, we have 568 * to restore it here to allow the buffer and VM 569 * to be freed. 570 */ 571 if (tbp->b_flags & B_DIRECT) 572 tbp->b_flags |= B_RELBUF; 573 } 574 bufdone(tbp); 575 } 576 pbrelvp(bp); 577 relpbuf(bp, &cluster_pbuf_freecnt); 578 } 579 580 /* 581 * cluster_wbuild_wb: 582 * 583 * Implement modified write build for cluster. 584 * 585 * write_behind = 0 write behind disabled 586 * write_behind = 1 write behind normal (default) 587 * write_behind = 2 write behind backed-off 588 */ 589 590 static __inline int 591 cluster_wbuild_wb(struct vnode *vp, long size, daddr_t start_lbn, int len, 592 int gbflags) 593 { 594 int r = 0; 595 596 switch (write_behind) { 597 case 2: 598 if (start_lbn < len) 599 break; 600 start_lbn -= len; 601 /* FALLTHROUGH */ 602 case 1: 603 r = cluster_wbuild(vp, size, start_lbn, len, gbflags); 604 /* FALLTHROUGH */ 605 default: 606 /* FALLTHROUGH */ 607 break; 608 } 609 return(r); 610 } 611 612 /* 613 * Do clustered write for FFS. 614 * 615 * Three cases: 616 * 1. Write is not sequential (write asynchronously) 617 * Write is sequential: 618 * 2. beginning of cluster - begin cluster 619 * 3. middle of a cluster - add to cluster 620 * 4. end of a cluster - asynchronously write cluster 621 */ 622 void 623 cluster_write(struct vnode *vp, struct buf *bp, u_quad_t filesize, int seqcount, 624 int gbflags) 625 { 626 daddr_t lbn; 627 int maxclen, cursize; 628 int lblocksize; 629 int async; 630 631 if (!unmapped_buf_allowed) 632 gbflags &= ~GB_UNMAPPED; 633 634 if (vp->v_type == VREG) { 635 async = DOINGASYNC(vp); 636 lblocksize = vp->v_mount->mnt_stat.f_iosize; 637 } else { 638 async = 0; 639 lblocksize = bp->b_bufsize; 640 } 641 lbn = bp->b_lblkno; 642 KASSERT(bp->b_offset != NOOFFSET, ("cluster_write: no buffer offset")); 643 644 /* Initialize vnode to beginning of file. */ 645 if (lbn == 0) 646 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0; 647 648 if (vp->v_clen == 0 || lbn != vp->v_lastw + 1 || 649 (bp->b_blkno != vp->v_lasta + btodb(lblocksize))) { 650 maxclen = vp->v_mount->mnt_iosize_max / lblocksize - 1; 651 if (vp->v_clen != 0) { 652 /* 653 * Next block is not sequential. 654 * 655 * If we are not writing at end of file, the process 656 * seeked to another point in the file since its last 657 * write, or we have reached our maximum cluster size, 658 * then push the previous cluster. Otherwise try 659 * reallocating to make it sequential. 660 * 661 * Change to algorithm: only push previous cluster if 662 * it was sequential from the point of view of the 663 * seqcount heuristic, otherwise leave the buffer 664 * intact so we can potentially optimize the I/O 665 * later on in the buf_daemon or update daemon 666 * flush. 667 */ 668 cursize = vp->v_lastw - vp->v_cstart + 1; 669 if (((u_quad_t) bp->b_offset + lblocksize) != filesize || 670 lbn != vp->v_lastw + 1 || vp->v_clen <= cursize) { 671 if (!async && seqcount > 0) { 672 cluster_wbuild_wb(vp, lblocksize, 673 vp->v_cstart, cursize, gbflags); 674 } 675 } else { 676 struct buf **bpp, **endbp; 677 struct cluster_save *buflist; 678 679 buflist = cluster_collectbufs(vp, bp, gbflags); 680 endbp = &buflist->bs_children 681 [buflist->bs_nchildren - 1]; 682 if (VOP_REALLOCBLKS(vp, buflist)) { 683 /* 684 * Failed, push the previous cluster 685 * if *really* writing sequentially 686 * in the logical file (seqcount > 1), 687 * otherwise delay it in the hopes that 688 * the low level disk driver can 689 * optimize the write ordering. 690 */ 691 for (bpp = buflist->bs_children; 692 bpp < endbp; bpp++) 693 brelse(*bpp); 694 free(buflist, M_SEGMENT); 695 if (seqcount > 1) { 696 cluster_wbuild_wb(vp, 697 lblocksize, vp->v_cstart, 698 cursize, gbflags); 699 } 700 } else { 701 /* 702 * Succeeded, keep building cluster. 703 */ 704 for (bpp = buflist->bs_children; 705 bpp <= endbp; bpp++) 706 bdwrite(*bpp); 707 free(buflist, M_SEGMENT); 708 vp->v_lastw = lbn; 709 vp->v_lasta = bp->b_blkno; 710 return; 711 } 712 } 713 } 714 /* 715 * Consider beginning a cluster. If at end of file, make 716 * cluster as large as possible, otherwise find size of 717 * existing cluster. 718 */ 719 if ((vp->v_type == VREG) && 720 ((u_quad_t) bp->b_offset + lblocksize) != filesize && 721 (bp->b_blkno == bp->b_lblkno) && 722 (VOP_BMAP(vp, lbn, NULL, &bp->b_blkno, &maxclen, NULL) || 723 bp->b_blkno == -1)) { 724 bawrite(bp); 725 vp->v_clen = 0; 726 vp->v_lasta = bp->b_blkno; 727 vp->v_cstart = lbn + 1; 728 vp->v_lastw = lbn; 729 return; 730 } 731 vp->v_clen = maxclen; 732 if (!async && maxclen == 0) { /* I/O not contiguous */ 733 vp->v_cstart = lbn + 1; 734 bawrite(bp); 735 } else { /* Wait for rest of cluster */ 736 vp->v_cstart = lbn; 737 bdwrite(bp); 738 } 739 } else if (lbn == vp->v_cstart + vp->v_clen) { 740 /* 741 * At end of cluster, write it out if seqcount tells us we 742 * are operating sequentially, otherwise let the buf or 743 * update daemon handle it. 744 */ 745 bdwrite(bp); 746 if (seqcount > 1) { 747 cluster_wbuild_wb(vp, lblocksize, vp->v_cstart, 748 vp->v_clen + 1, gbflags); 749 } 750 vp->v_clen = 0; 751 vp->v_cstart = lbn + 1; 752 } else if (vm_page_count_severe()) { 753 /* 754 * We are low on memory, get it going NOW 755 */ 756 bawrite(bp); 757 } else { 758 /* 759 * In the middle of a cluster, so just delay the I/O for now. 760 */ 761 bdwrite(bp); 762 } 763 vp->v_lastw = lbn; 764 vp->v_lasta = bp->b_blkno; 765 } 766 767 768 /* 769 * This is an awful lot like cluster_rbuild...wish they could be combined. 770 * The last lbn argument is the current block on which I/O is being 771 * performed. Check to see that it doesn't fall in the middle of 772 * the current block (if last_bp == NULL). 773 */ 774 int 775 cluster_wbuild(struct vnode *vp, long size, daddr_t start_lbn, int len, 776 int gbflags) 777 { 778 struct buf *bp, *tbp; 779 struct bufobj *bo; 780 int i, j; 781 int totalwritten = 0; 782 int dbsize = btodb(size); 783 784 if (!unmapped_buf_allowed) 785 gbflags &= ~GB_UNMAPPED; 786 787 bo = &vp->v_bufobj; 788 while (len > 0) { 789 /* 790 * If the buffer is not delayed-write (i.e. dirty), or it 791 * is delayed-write but either locked or inval, it cannot 792 * partake in the clustered write. 793 */ 794 BO_LOCK(bo); 795 if ((tbp = gbincore(&vp->v_bufobj, start_lbn)) == NULL || 796 (tbp->b_vflags & BV_BKGRDINPROG)) { 797 BO_UNLOCK(bo); 798 ++start_lbn; 799 --len; 800 continue; 801 } 802 if (BUF_LOCK(tbp, 803 LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, BO_LOCKPTR(bo))) { 804 ++start_lbn; 805 --len; 806 continue; 807 } 808 if ((tbp->b_flags & (B_INVAL | B_DELWRI)) != B_DELWRI) { 809 BUF_UNLOCK(tbp); 810 ++start_lbn; 811 --len; 812 continue; 813 } 814 if (tbp->b_pin_count > 0) { 815 BUF_UNLOCK(tbp); 816 ++start_lbn; 817 --len; 818 continue; 819 } 820 bremfree(tbp); 821 tbp->b_flags &= ~B_DONE; 822 823 /* 824 * Extra memory in the buffer, punt on this buffer. 825 * XXX we could handle this in most cases, but we would 826 * have to push the extra memory down to after our max 827 * possible cluster size and then potentially pull it back 828 * up if the cluster was terminated prematurely--too much 829 * hassle. 830 */ 831 if (((tbp->b_flags & (B_CLUSTEROK | B_MALLOC | B_VMIO)) != 832 (B_CLUSTEROK | B_VMIO)) || 833 (tbp->b_bcount != tbp->b_bufsize) || 834 (tbp->b_bcount != size) || 835 (len == 1) || 836 ((bp = (vp->v_vflag & VV_MD) != 0 ? 837 trypbuf(&cluster_pbuf_freecnt) : 838 getpbuf(&cluster_pbuf_freecnt)) == NULL)) { 839 totalwritten += tbp->b_bufsize; 840 bawrite(tbp); 841 ++start_lbn; 842 --len; 843 continue; 844 } 845 846 /* 847 * We got a pbuf to make the cluster in. 848 * so initialise it. 849 */ 850 TAILQ_INIT(&bp->b_cluster.cluster_head); 851 bp->b_bcount = 0; 852 bp->b_bufsize = 0; 853 bp->b_npages = 0; 854 if (tbp->b_wcred != NOCRED) 855 bp->b_wcred = crhold(tbp->b_wcred); 856 857 bp->b_blkno = tbp->b_blkno; 858 bp->b_lblkno = tbp->b_lblkno; 859 bp->b_offset = tbp->b_offset; 860 861 /* 862 * We are synthesizing a buffer out of vm_page_t's, but 863 * if the block size is not page aligned then the starting 864 * address may not be either. Inherit the b_data offset 865 * from the original buffer. 866 */ 867 if ((gbflags & GB_UNMAPPED) == 0 || 868 (tbp->b_flags & B_VMIO) == 0) { 869 bp->b_data = (char *)((vm_offset_t)bp->b_data | 870 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 871 } else { 872 bp->b_data = unmapped_buf; 873 } 874 bp->b_flags |= B_CLUSTER | (tbp->b_flags & (B_VMIO | 875 B_NEEDCOMMIT)); 876 bp->b_iodone = cluster_callback; 877 pbgetvp(vp, bp); 878 /* 879 * From this location in the file, scan forward to see 880 * if there are buffers with adjacent data that need to 881 * be written as well. 882 */ 883 for (i = 0; i < len; ++i, ++start_lbn) { 884 if (i != 0) { /* If not the first buffer */ 885 /* 886 * If the adjacent data is not even in core it 887 * can't need to be written. 888 */ 889 BO_LOCK(bo); 890 if ((tbp = gbincore(bo, start_lbn)) == NULL || 891 (tbp->b_vflags & BV_BKGRDINPROG)) { 892 BO_UNLOCK(bo); 893 break; 894 } 895 896 /* 897 * If it IS in core, but has different 898 * characteristics, or is locked (which 899 * means it could be undergoing a background 900 * I/O or be in a weird state), then don't 901 * cluster with it. 902 */ 903 if (BUF_LOCK(tbp, 904 LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, 905 BO_LOCKPTR(bo))) 906 break; 907 908 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK | 909 B_INVAL | B_DELWRI | B_NEEDCOMMIT)) 910 != (B_DELWRI | B_CLUSTEROK | 911 (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) || 912 tbp->b_wcred != bp->b_wcred) { 913 BUF_UNLOCK(tbp); 914 break; 915 } 916 917 /* 918 * Check that the combined cluster 919 * would make sense with regard to pages 920 * and would not be too large 921 */ 922 if ((tbp->b_bcount != size) || 923 ((bp->b_blkno + (dbsize * i)) != 924 tbp->b_blkno) || 925 ((tbp->b_npages + bp->b_npages) > 926 (vp->v_mount->mnt_iosize_max / PAGE_SIZE))) { 927 BUF_UNLOCK(tbp); 928 break; 929 } 930 931 /* 932 * Do not pull in pinned buffers. 933 */ 934 if (tbp->b_pin_count > 0) { 935 BUF_UNLOCK(tbp); 936 break; 937 } 938 939 /* 940 * Ok, it's passed all the tests, 941 * so remove it from the free list 942 * and mark it busy. We will use it. 943 */ 944 bremfree(tbp); 945 tbp->b_flags &= ~B_DONE; 946 } /* end of code for non-first buffers only */ 947 /* 948 * If the IO is via the VM then we do some 949 * special VM hackery (yuck). Since the buffer's 950 * block size may not be page-aligned it is possible 951 * for a page to be shared between two buffers. We 952 * have to get rid of the duplication when building 953 * the cluster. 954 */ 955 if (tbp->b_flags & B_VMIO) { 956 vm_page_t m; 957 958 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object); 959 if (i == 0) { 960 vfs_drain_busy_pages(tbp); 961 } else { /* if not first buffer */ 962 for (j = 0; j < tbp->b_npages; j += 1) { 963 m = tbp->b_pages[j]; 964 if (vm_page_xbusied(m)) { 965 VM_OBJECT_WUNLOCK( 966 tbp->b_object); 967 bqrelse(tbp); 968 goto finishcluster; 969 } 970 } 971 } 972 for (j = 0; j < tbp->b_npages; j += 1) { 973 m = tbp->b_pages[j]; 974 vm_page_sbusy(m); 975 vm_object_pip_add(m->object, 1); 976 if ((bp->b_npages == 0) || 977 (bp->b_pages[bp->b_npages - 1] != m)) { 978 bp->b_pages[bp->b_npages] = m; 979 bp->b_npages++; 980 } 981 } 982 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object); 983 } 984 bp->b_bcount += size; 985 bp->b_bufsize += size; 986 /* 987 * If any of the clustered buffers have their 988 * B_BARRIER flag set, transfer that request to 989 * the cluster. 990 */ 991 bp->b_flags |= (tbp->b_flags & B_BARRIER); 992 tbp->b_flags &= ~(B_DONE | B_BARRIER); 993 tbp->b_flags |= B_ASYNC; 994 tbp->b_ioflags &= ~BIO_ERROR; 995 tbp->b_iocmd = BIO_WRITE; 996 bundirty(tbp); 997 reassignbuf(tbp); /* put on clean list */ 998 bufobj_wref(tbp->b_bufobj); 999 BUF_KERNPROC(tbp); 1000 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head, 1001 tbp, b_cluster.cluster_entry); 1002 } 1003 finishcluster: 1004 if (buf_mapped(bp)) { 1005 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 1006 (vm_page_t *)bp->b_pages, bp->b_npages); 1007 } 1008 if (bp->b_bufsize > bp->b_kvasize) 1009 panic( 1010 "cluster_wbuild: b_bufsize(%ld) > b_kvasize(%d)\n", 1011 bp->b_bufsize, bp->b_kvasize); 1012 totalwritten += bp->b_bufsize; 1013 bp->b_dirtyoff = 0; 1014 bp->b_dirtyend = bp->b_bufsize; 1015 bawrite(bp); 1016 1017 len -= i; 1018 } 1019 return totalwritten; 1020 } 1021 1022 /* 1023 * Collect together all the buffers in a cluster. 1024 * Plus add one additional buffer. 1025 */ 1026 static struct cluster_save * 1027 cluster_collectbufs(struct vnode *vp, struct buf *last_bp, int gbflags) 1028 { 1029 struct cluster_save *buflist; 1030 struct buf *bp; 1031 daddr_t lbn; 1032 int i, len; 1033 1034 len = vp->v_lastw - vp->v_cstart + 1; 1035 buflist = malloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist), 1036 M_SEGMENT, M_WAITOK); 1037 buflist->bs_nchildren = 0; 1038 buflist->bs_children = (struct buf **) (buflist + 1); 1039 for (lbn = vp->v_cstart, i = 0; i < len; lbn++, i++) { 1040 (void)bread_gb(vp, lbn, last_bp->b_bcount, NOCRED, 1041 gbflags, &bp); 1042 buflist->bs_children[i] = bp; 1043 if (bp->b_blkno == bp->b_lblkno) 1044 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, 1045 NULL, NULL); 1046 } 1047 buflist->bs_children[i] = bp = last_bp; 1048 if (bp->b_blkno == bp->b_lblkno) 1049 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 1050 buflist->bs_nchildren = i + 1; 1051 return (buflist); 1052 } 1053