1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1993 5 * The Regents of the University of California. All rights reserved. 6 * Modifications/enhancements: 7 * Copyright (c) 1995 John S. Dyson. All rights reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * @(#)vfs_cluster.c 8.7 (Berkeley) 2/13/94 34 */ 35 36 #include <sys/cdefs.h> 37 __FBSDID("$FreeBSD$"); 38 39 #include "opt_debug_cluster.h" 40 41 #include <sys/param.h> 42 #include <sys/systm.h> 43 #include <sys/kernel.h> 44 #include <sys/proc.h> 45 #include <sys/bio.h> 46 #include <sys/buf.h> 47 #include <sys/vnode.h> 48 #include <sys/malloc.h> 49 #include <sys/mount.h> 50 #include <sys/racct.h> 51 #include <sys/resourcevar.h> 52 #include <sys/rwlock.h> 53 #include <sys/vmmeter.h> 54 #include <vm/vm.h> 55 #include <vm/vm_object.h> 56 #include <vm/vm_page.h> 57 #include <sys/sysctl.h> 58 59 #if defined(CLUSTERDEBUG) 60 static int rcluster= 0; 61 SYSCTL_INT(_debug, OID_AUTO, rcluster, CTLFLAG_RW, &rcluster, 0, 62 "Debug VFS clustering code"); 63 #endif 64 65 static MALLOC_DEFINE(M_SEGMENT, "cl_savebuf", "cluster_save buffer"); 66 static uma_zone_t cluster_pbuf_zone; 67 68 static void cluster_init(void *); 69 static struct cluster_save *cluster_collectbufs(struct vnode *vp, 70 struct buf *last_bp, int gbflags); 71 static struct buf *cluster_rbuild(struct vnode *vp, u_quad_t filesize, 72 daddr_t lbn, daddr_t blkno, long size, int run, int gbflags, 73 struct buf *fbp); 74 static void cluster_callback(struct buf *); 75 76 static int write_behind = 1; 77 SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0, 78 "Cluster write-behind; 0: disable, 1: enable, 2: backed off"); 79 80 static int read_max = 64; 81 SYSCTL_INT(_vfs, OID_AUTO, read_max, CTLFLAG_RW, &read_max, 0, 82 "Cluster read-ahead max block count"); 83 84 static int read_min = 1; 85 SYSCTL_INT(_vfs, OID_AUTO, read_min, CTLFLAG_RW, &read_min, 0, 86 "Cluster read min block count"); 87 88 SYSINIT(cluster, SI_SUB_CPU, SI_ORDER_ANY, cluster_init, NULL); 89 90 static void 91 cluster_init(void *dummy) 92 { 93 94 cluster_pbuf_zone = pbuf_zsecond_create("clpbuf", nswbuf / 2); 95 } 96 97 /* 98 * Read data to a buf, including read-ahead if we find this to be beneficial. 99 * cluster_read replaces bread. 100 */ 101 int 102 cluster_read(struct vnode *vp, u_quad_t filesize, daddr_t lblkno, long size, 103 struct ucred *cred, long totread, int seqcount, int gbflags, 104 struct buf **bpp) 105 { 106 struct buf *bp, *rbp, *reqbp; 107 struct bufobj *bo; 108 struct thread *td; 109 daddr_t blkno, origblkno; 110 int maxra, racluster; 111 int error, ncontig; 112 int i; 113 114 error = 0; 115 td = curthread; 116 bo = &vp->v_bufobj; 117 if (!unmapped_buf_allowed) 118 gbflags &= ~GB_UNMAPPED; 119 120 /* 121 * Try to limit the amount of read-ahead by a few 122 * ad-hoc parameters. This needs work!!! 123 */ 124 racluster = vp->v_mount->mnt_iosize_max / size; 125 maxra = seqcount; 126 maxra = min(read_max, maxra); 127 maxra = min(nbuf/8, maxra); 128 if (((u_quad_t)(lblkno + maxra + 1) * size) > filesize) 129 maxra = (filesize / size) - lblkno; 130 131 /* 132 * get the requested block 133 */ 134 error = getblkx(vp, lblkno, lblkno, size, 0, 0, gbflags, &bp); 135 if (error != 0) { 136 *bpp = NULL; 137 return (error); 138 } 139 gbflags &= ~GB_NOSPARSE; 140 origblkno = lblkno; 141 *bpp = reqbp = bp; 142 143 /* 144 * if it is in the cache, then check to see if the reads have been 145 * sequential. If they have, then try some read-ahead, otherwise 146 * back-off on prospective read-aheads. 147 */ 148 if (bp->b_flags & B_CACHE) { 149 if (!seqcount) { 150 return 0; 151 } else if ((bp->b_flags & B_RAM) == 0) { 152 return 0; 153 } else { 154 bp->b_flags &= ~B_RAM; 155 BO_RLOCK(bo); 156 for (i = 1; i < maxra; i++) { 157 /* 158 * Stop if the buffer does not exist or it 159 * is invalid (about to go away?) 160 */ 161 rbp = gbincore(&vp->v_bufobj, lblkno+i); 162 if (rbp == NULL || (rbp->b_flags & B_INVAL)) 163 break; 164 165 /* 166 * Set another read-ahead mark so we know 167 * to check again. (If we can lock the 168 * buffer without waiting) 169 */ 170 if ((((i % racluster) == (racluster - 1)) || 171 (i == (maxra - 1))) 172 && (0 == BUF_LOCK(rbp, 173 LK_EXCLUSIVE | LK_NOWAIT, NULL))) { 174 rbp->b_flags |= B_RAM; 175 BUF_UNLOCK(rbp); 176 } 177 } 178 BO_RUNLOCK(bo); 179 if (i >= maxra) { 180 return 0; 181 } 182 lblkno += i; 183 } 184 reqbp = bp = NULL; 185 /* 186 * If it isn't in the cache, then get a chunk from 187 * disk if sequential, otherwise just get the block. 188 */ 189 } else { 190 off_t firstread = bp->b_offset; 191 int nblks; 192 long minread; 193 194 KASSERT(bp->b_offset != NOOFFSET, 195 ("cluster_read: no buffer offset")); 196 197 ncontig = 0; 198 199 /* 200 * Adjust totread if needed 201 */ 202 minread = read_min * size; 203 if (minread > totread) 204 totread = minread; 205 206 /* 207 * Compute the total number of blocks that we should read 208 * synchronously. 209 */ 210 if (firstread + totread > filesize) 211 totread = filesize - firstread; 212 nblks = howmany(totread, size); 213 if (nblks > racluster) 214 nblks = racluster; 215 216 /* 217 * Now compute the number of contiguous blocks. 218 */ 219 if (nblks > 1) { 220 error = VOP_BMAP(vp, lblkno, NULL, 221 &blkno, &ncontig, NULL); 222 /* 223 * If this failed to map just do the original block. 224 */ 225 if (error || blkno == -1) 226 ncontig = 0; 227 } 228 229 /* 230 * If we have contiguous data available do a cluster 231 * otherwise just read the requested block. 232 */ 233 if (ncontig) { 234 /* Account for our first block. */ 235 ncontig = min(ncontig + 1, nblks); 236 if (ncontig < nblks) 237 nblks = ncontig; 238 bp = cluster_rbuild(vp, filesize, lblkno, 239 blkno, size, nblks, gbflags, bp); 240 lblkno += (bp->b_bufsize / size); 241 } else { 242 bp->b_flags |= B_RAM; 243 bp->b_iocmd = BIO_READ; 244 lblkno += 1; 245 } 246 } 247 248 /* 249 * handle the synchronous read so that it is available ASAP. 250 */ 251 if (bp) { 252 if ((bp->b_flags & B_CLUSTER) == 0) { 253 vfs_busy_pages(bp, 0); 254 } 255 bp->b_flags &= ~B_INVAL; 256 bp->b_ioflags &= ~BIO_ERROR; 257 if ((bp->b_flags & B_ASYNC) || bp->b_iodone != NULL) 258 BUF_KERNPROC(bp); 259 bp->b_iooffset = dbtob(bp->b_blkno); 260 bstrategy(bp); 261 #ifdef RACCT 262 if (racct_enable) { 263 PROC_LOCK(td->td_proc); 264 racct_add_buf(td->td_proc, bp, 0); 265 PROC_UNLOCK(td->td_proc); 266 } 267 #endif /* RACCT */ 268 td->td_ru.ru_inblock++; 269 } 270 271 /* 272 * If we have been doing sequential I/O, then do some read-ahead. 273 */ 274 while (lblkno < (origblkno + maxra)) { 275 error = VOP_BMAP(vp, lblkno, NULL, &blkno, &ncontig, NULL); 276 if (error) 277 break; 278 279 if (blkno == -1) 280 break; 281 282 /* 283 * We could throttle ncontig here by maxra but we might as 284 * well read the data if it is contiguous. We're throttled 285 * by racluster anyway. 286 */ 287 if (ncontig) { 288 ncontig = min(ncontig + 1, racluster); 289 rbp = cluster_rbuild(vp, filesize, lblkno, blkno, 290 size, ncontig, gbflags, NULL); 291 lblkno += (rbp->b_bufsize / size); 292 if (rbp->b_flags & B_DELWRI) { 293 bqrelse(rbp); 294 continue; 295 } 296 } else { 297 rbp = getblk(vp, lblkno, size, 0, 0, gbflags); 298 lblkno += 1; 299 if (rbp->b_flags & B_DELWRI) { 300 bqrelse(rbp); 301 continue; 302 } 303 rbp->b_flags |= B_ASYNC | B_RAM; 304 rbp->b_iocmd = BIO_READ; 305 rbp->b_blkno = blkno; 306 } 307 if (rbp->b_flags & B_CACHE) { 308 rbp->b_flags &= ~B_ASYNC; 309 bqrelse(rbp); 310 continue; 311 } 312 if ((rbp->b_flags & B_CLUSTER) == 0) { 313 vfs_busy_pages(rbp, 0); 314 } 315 rbp->b_flags &= ~B_INVAL; 316 rbp->b_ioflags &= ~BIO_ERROR; 317 if ((rbp->b_flags & B_ASYNC) || rbp->b_iodone != NULL) 318 BUF_KERNPROC(rbp); 319 rbp->b_iooffset = dbtob(rbp->b_blkno); 320 bstrategy(rbp); 321 #ifdef RACCT 322 if (racct_enable) { 323 PROC_LOCK(td->td_proc); 324 racct_add_buf(td->td_proc, rbp, 0); 325 PROC_UNLOCK(td->td_proc); 326 } 327 #endif /* RACCT */ 328 td->td_ru.ru_inblock++; 329 } 330 331 if (reqbp) { 332 /* 333 * Like bread, always brelse() the buffer when 334 * returning an error. 335 */ 336 error = bufwait(reqbp); 337 if (error != 0) { 338 brelse(reqbp); 339 *bpp = NULL; 340 } 341 } 342 return (error); 343 } 344 345 /* 346 * If blocks are contiguous on disk, use this to provide clustered 347 * read ahead. We will read as many blocks as possible sequentially 348 * and then parcel them up into logical blocks in the buffer hash table. 349 */ 350 static struct buf * 351 cluster_rbuild(struct vnode *vp, u_quad_t filesize, daddr_t lbn, 352 daddr_t blkno, long size, int run, int gbflags, struct buf *fbp) 353 { 354 struct buf *bp, *tbp; 355 daddr_t bn; 356 off_t off; 357 long tinc, tsize; 358 int i, inc, j, k, toff; 359 360 KASSERT(size == vp->v_mount->mnt_stat.f_iosize, 361 ("cluster_rbuild: size %ld != f_iosize %jd\n", 362 size, (intmax_t)vp->v_mount->mnt_stat.f_iosize)); 363 364 /* 365 * avoid a division 366 */ 367 while ((u_quad_t) size * (lbn + run) > filesize) { 368 --run; 369 } 370 371 if (fbp) { 372 tbp = fbp; 373 tbp->b_iocmd = BIO_READ; 374 } else { 375 tbp = getblk(vp, lbn, size, 0, 0, gbflags); 376 if (tbp->b_flags & B_CACHE) 377 return tbp; 378 tbp->b_flags |= B_ASYNC | B_RAM; 379 tbp->b_iocmd = BIO_READ; 380 } 381 tbp->b_blkno = blkno; 382 if( (tbp->b_flags & B_MALLOC) || 383 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1) ) 384 return tbp; 385 386 bp = uma_zalloc(cluster_pbuf_zone, M_NOWAIT); 387 if (bp == NULL) 388 return tbp; 389 390 /* 391 * We are synthesizing a buffer out of vm_page_t's, but 392 * if the block size is not page aligned then the starting 393 * address may not be either. Inherit the b_data offset 394 * from the original buffer. 395 */ 396 bp->b_flags = B_ASYNC | B_CLUSTER | B_VMIO; 397 if ((gbflags & GB_UNMAPPED) != 0) { 398 bp->b_data = unmapped_buf; 399 } else { 400 bp->b_data = (char *)((vm_offset_t)bp->b_data | 401 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 402 } 403 bp->b_iocmd = BIO_READ; 404 bp->b_iodone = cluster_callback; 405 bp->b_blkno = blkno; 406 bp->b_lblkno = lbn; 407 bp->b_offset = tbp->b_offset; 408 KASSERT(bp->b_offset != NOOFFSET, ("cluster_rbuild: no buffer offset")); 409 pbgetvp(vp, bp); 410 411 TAILQ_INIT(&bp->b_cluster.cluster_head); 412 413 bp->b_bcount = 0; 414 bp->b_bufsize = 0; 415 bp->b_npages = 0; 416 417 inc = btodb(size); 418 for (bn = blkno, i = 0; i < run; ++i, bn += inc) { 419 if (i == 0) { 420 vm_object_pip_add(tbp->b_bufobj->bo_object, 421 tbp->b_npages); 422 vfs_busy_pages_acquire(tbp); 423 } else { 424 if ((bp->b_npages * PAGE_SIZE) + 425 round_page(size) > vp->v_mount->mnt_iosize_max) { 426 break; 427 } 428 429 tbp = getblk(vp, lbn + i, size, 0, 0, GB_LOCK_NOWAIT | 430 (gbflags & GB_UNMAPPED)); 431 432 /* Don't wait around for locked bufs. */ 433 if (tbp == NULL) 434 break; 435 436 /* 437 * Stop scanning if the buffer is fully valid 438 * (marked B_CACHE), or locked (may be doing a 439 * background write), or if the buffer is not 440 * VMIO backed. The clustering code can only deal 441 * with VMIO-backed buffers. The bo lock is not 442 * required for the BKGRDINPROG check since it 443 * can not be set without the buf lock. 444 */ 445 if ((tbp->b_vflags & BV_BKGRDINPROG) || 446 (tbp->b_flags & B_CACHE) || 447 (tbp->b_flags & B_VMIO) == 0) { 448 bqrelse(tbp); 449 break; 450 } 451 452 /* 453 * The buffer must be completely invalid in order to 454 * take part in the cluster. If it is partially valid 455 * then we stop. 456 */ 457 off = tbp->b_offset; 458 tsize = size; 459 for (j = 0; tsize > 0; j++) { 460 toff = off & PAGE_MASK; 461 tinc = tsize; 462 if (toff + tinc > PAGE_SIZE) 463 tinc = PAGE_SIZE - toff; 464 if (vm_page_trysbusy(tbp->b_pages[j]) == 0) 465 break; 466 if ((tbp->b_pages[j]->valid & 467 vm_page_bits(toff, tinc)) != 0) { 468 vm_page_sunbusy(tbp->b_pages[j]); 469 break; 470 } 471 vm_object_pip_add(tbp->b_bufobj->bo_object, 1); 472 off += tinc; 473 tsize -= tinc; 474 } 475 if (tsize > 0) { 476 clean_sbusy: 477 vm_object_pip_wakeupn(tbp->b_bufobj->bo_object, 478 j); 479 for (k = 0; k < j; k++) 480 vm_page_sunbusy(tbp->b_pages[k]); 481 bqrelse(tbp); 482 break; 483 } 484 485 /* 486 * Set a read-ahead mark as appropriate 487 */ 488 if ((fbp && (i == 1)) || (i == (run - 1))) 489 tbp->b_flags |= B_RAM; 490 491 /* 492 * Set the buffer up for an async read (XXX should 493 * we do this only if we do not wind up brelse()ing?). 494 * Set the block number if it isn't set, otherwise 495 * if it is make sure it matches the block number we 496 * expect. 497 */ 498 tbp->b_flags |= B_ASYNC; 499 tbp->b_iocmd = BIO_READ; 500 if (tbp->b_blkno == tbp->b_lblkno) { 501 tbp->b_blkno = bn; 502 } else if (tbp->b_blkno != bn) { 503 goto clean_sbusy; 504 } 505 } 506 /* 507 * XXX fbp from caller may not be B_ASYNC, but we are going 508 * to biodone() it in cluster_callback() anyway 509 */ 510 BUF_KERNPROC(tbp); 511 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head, 512 tbp, b_cluster.cluster_entry); 513 for (j = 0; j < tbp->b_npages; j += 1) { 514 vm_page_t m; 515 516 m = tbp->b_pages[j]; 517 if ((bp->b_npages == 0) || 518 (bp->b_pages[bp->b_npages-1] != m)) { 519 bp->b_pages[bp->b_npages] = m; 520 bp->b_npages++; 521 } 522 if (vm_page_all_valid(m)) 523 tbp->b_pages[j] = bogus_page; 524 } 525 526 /* 527 * Don't inherit tbp->b_bufsize as it may be larger due to 528 * a non-page-aligned size. Instead just aggregate using 529 * 'size'. 530 */ 531 if (tbp->b_bcount != size) 532 printf("warning: tbp->b_bcount wrong %ld vs %ld\n", tbp->b_bcount, size); 533 if (tbp->b_bufsize != size) 534 printf("warning: tbp->b_bufsize wrong %ld vs %ld\n", tbp->b_bufsize, size); 535 bp->b_bcount += size; 536 bp->b_bufsize += size; 537 } 538 539 /* 540 * Fully valid pages in the cluster are already good and do not need 541 * to be re-read from disk. Replace the page with bogus_page 542 */ 543 for (j = 0; j < bp->b_npages; j++) { 544 if (vm_page_all_valid(bp->b_pages[j])) 545 bp->b_pages[j] = bogus_page; 546 } 547 if (bp->b_bufsize > bp->b_kvasize) 548 panic("cluster_rbuild: b_bufsize(%ld) > b_kvasize(%d)\n", 549 bp->b_bufsize, bp->b_kvasize); 550 551 if (buf_mapped(bp)) { 552 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 553 (vm_page_t *)bp->b_pages, bp->b_npages); 554 } 555 return (bp); 556 } 557 558 /* 559 * Cleanup after a clustered read or write. 560 * This is complicated by the fact that any of the buffers might have 561 * extra memory (if there were no empty buffer headers at allocbuf time) 562 * that we will need to shift around. 563 */ 564 static void 565 cluster_callback(struct buf *bp) 566 { 567 struct buf *nbp, *tbp; 568 int error = 0; 569 570 /* 571 * Must propagate errors to all the components. 572 */ 573 if (bp->b_ioflags & BIO_ERROR) 574 error = bp->b_error; 575 576 if (buf_mapped(bp)) { 577 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), 578 bp->b_npages); 579 } 580 /* 581 * Move memory from the large cluster buffer into the component 582 * buffers and mark IO as done on these. 583 */ 584 for (tbp = TAILQ_FIRST(&bp->b_cluster.cluster_head); 585 tbp; tbp = nbp) { 586 nbp = TAILQ_NEXT(&tbp->b_cluster, cluster_entry); 587 if (error) { 588 tbp->b_ioflags |= BIO_ERROR; 589 tbp->b_error = error; 590 } else { 591 tbp->b_dirtyoff = tbp->b_dirtyend = 0; 592 tbp->b_flags &= ~B_INVAL; 593 tbp->b_ioflags &= ~BIO_ERROR; 594 /* 595 * XXX the bdwrite()/bqrelse() issued during 596 * cluster building clears B_RELBUF (see bqrelse() 597 * comment). If direct I/O was specified, we have 598 * to restore it here to allow the buffer and VM 599 * to be freed. 600 */ 601 if (tbp->b_flags & B_DIRECT) 602 tbp->b_flags |= B_RELBUF; 603 } 604 bufdone(tbp); 605 } 606 pbrelvp(bp); 607 uma_zfree(cluster_pbuf_zone, bp); 608 } 609 610 /* 611 * cluster_wbuild_wb: 612 * 613 * Implement modified write build for cluster. 614 * 615 * write_behind = 0 write behind disabled 616 * write_behind = 1 write behind normal (default) 617 * write_behind = 2 write behind backed-off 618 */ 619 620 static __inline int 621 cluster_wbuild_wb(struct vnode *vp, long size, daddr_t start_lbn, int len, 622 int gbflags) 623 { 624 int r = 0; 625 626 switch (write_behind) { 627 case 2: 628 if (start_lbn < len) 629 break; 630 start_lbn -= len; 631 /* FALLTHROUGH */ 632 case 1: 633 r = cluster_wbuild(vp, size, start_lbn, len, gbflags); 634 /* FALLTHROUGH */ 635 default: 636 /* FALLTHROUGH */ 637 break; 638 } 639 return(r); 640 } 641 642 /* 643 * Do clustered write for FFS. 644 * 645 * Three cases: 646 * 1. Write is not sequential (write asynchronously) 647 * Write is sequential: 648 * 2. beginning of cluster - begin cluster 649 * 3. middle of a cluster - add to cluster 650 * 4. end of a cluster - asynchronously write cluster 651 */ 652 void 653 cluster_write(struct vnode *vp, struct buf *bp, u_quad_t filesize, int seqcount, 654 int gbflags) 655 { 656 daddr_t lbn; 657 int maxclen, cursize; 658 int lblocksize; 659 int async; 660 661 if (!unmapped_buf_allowed) 662 gbflags &= ~GB_UNMAPPED; 663 664 if (vp->v_type == VREG) { 665 async = DOINGASYNC(vp); 666 lblocksize = vp->v_mount->mnt_stat.f_iosize; 667 } else { 668 async = 0; 669 lblocksize = bp->b_bufsize; 670 } 671 lbn = bp->b_lblkno; 672 KASSERT(bp->b_offset != NOOFFSET, ("cluster_write: no buffer offset")); 673 674 /* Initialize vnode to beginning of file. */ 675 if (lbn == 0) 676 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0; 677 678 if (vp->v_clen == 0 || lbn != vp->v_lastw + 1 || 679 (bp->b_blkno != vp->v_lasta + btodb(lblocksize))) { 680 maxclen = vp->v_mount->mnt_iosize_max / lblocksize - 1; 681 if (vp->v_clen != 0) { 682 /* 683 * Next block is not sequential. 684 * 685 * If we are not writing at end of file, the process 686 * seeked to another point in the file since its last 687 * write, or we have reached our maximum cluster size, 688 * then push the previous cluster. Otherwise try 689 * reallocating to make it sequential. 690 * 691 * Change to algorithm: only push previous cluster if 692 * it was sequential from the point of view of the 693 * seqcount heuristic, otherwise leave the buffer 694 * intact so we can potentially optimize the I/O 695 * later on in the buf_daemon or update daemon 696 * flush. 697 */ 698 cursize = vp->v_lastw - vp->v_cstart + 1; 699 if (((u_quad_t) bp->b_offset + lblocksize) != filesize || 700 lbn != vp->v_lastw + 1 || vp->v_clen <= cursize) { 701 if (!async && seqcount > 0) { 702 cluster_wbuild_wb(vp, lblocksize, 703 vp->v_cstart, cursize, gbflags); 704 } 705 } else { 706 struct buf **bpp, **endbp; 707 struct cluster_save *buflist; 708 709 buflist = cluster_collectbufs(vp, bp, gbflags); 710 if (buflist == NULL) { 711 /* 712 * Cluster build failed so just write 713 * it now. 714 */ 715 bawrite(bp); 716 return; 717 } 718 endbp = &buflist->bs_children 719 [buflist->bs_nchildren - 1]; 720 if (VOP_REALLOCBLKS(vp, buflist)) { 721 /* 722 * Failed, push the previous cluster 723 * if *really* writing sequentially 724 * in the logical file (seqcount > 1), 725 * otherwise delay it in the hopes that 726 * the low level disk driver can 727 * optimize the write ordering. 728 */ 729 for (bpp = buflist->bs_children; 730 bpp < endbp; bpp++) 731 brelse(*bpp); 732 free(buflist, M_SEGMENT); 733 if (seqcount > 1) { 734 cluster_wbuild_wb(vp, 735 lblocksize, vp->v_cstart, 736 cursize, gbflags); 737 } 738 } else { 739 /* 740 * Succeeded, keep building cluster. 741 */ 742 for (bpp = buflist->bs_children; 743 bpp <= endbp; bpp++) 744 bdwrite(*bpp); 745 free(buflist, M_SEGMENT); 746 vp->v_lastw = lbn; 747 vp->v_lasta = bp->b_blkno; 748 return; 749 } 750 } 751 } 752 /* 753 * Consider beginning a cluster. If at end of file, make 754 * cluster as large as possible, otherwise find size of 755 * existing cluster. 756 */ 757 if ((vp->v_type == VREG) && 758 ((u_quad_t) bp->b_offset + lblocksize) != filesize && 759 (bp->b_blkno == bp->b_lblkno) && 760 (VOP_BMAP(vp, lbn, NULL, &bp->b_blkno, &maxclen, NULL) || 761 bp->b_blkno == -1)) { 762 bawrite(bp); 763 vp->v_clen = 0; 764 vp->v_lasta = bp->b_blkno; 765 vp->v_cstart = lbn + 1; 766 vp->v_lastw = lbn; 767 return; 768 } 769 vp->v_clen = maxclen; 770 if (!async && maxclen == 0) { /* I/O not contiguous */ 771 vp->v_cstart = lbn + 1; 772 bawrite(bp); 773 } else { /* Wait for rest of cluster */ 774 vp->v_cstart = lbn; 775 bdwrite(bp); 776 } 777 } else if (lbn == vp->v_cstart + vp->v_clen) { 778 /* 779 * At end of cluster, write it out if seqcount tells us we 780 * are operating sequentially, otherwise let the buf or 781 * update daemon handle it. 782 */ 783 bdwrite(bp); 784 if (seqcount > 1) { 785 cluster_wbuild_wb(vp, lblocksize, vp->v_cstart, 786 vp->v_clen + 1, gbflags); 787 } 788 vp->v_clen = 0; 789 vp->v_cstart = lbn + 1; 790 } else if (vm_page_count_severe()) { 791 /* 792 * We are low on memory, get it going NOW 793 */ 794 bawrite(bp); 795 } else { 796 /* 797 * In the middle of a cluster, so just delay the I/O for now. 798 */ 799 bdwrite(bp); 800 } 801 vp->v_lastw = lbn; 802 vp->v_lasta = bp->b_blkno; 803 } 804 805 /* 806 * This is an awful lot like cluster_rbuild...wish they could be combined. 807 * The last lbn argument is the current block on which I/O is being 808 * performed. Check to see that it doesn't fall in the middle of 809 * the current block (if last_bp == NULL). 810 */ 811 int 812 cluster_wbuild(struct vnode *vp, long size, daddr_t start_lbn, int len, 813 int gbflags) 814 { 815 struct buf *bp, *tbp; 816 struct bufobj *bo; 817 int i, j; 818 int totalwritten = 0; 819 int dbsize = btodb(size); 820 821 if (!unmapped_buf_allowed) 822 gbflags &= ~GB_UNMAPPED; 823 824 bo = &vp->v_bufobj; 825 while (len > 0) { 826 /* 827 * If the buffer is not delayed-write (i.e. dirty), or it 828 * is delayed-write but either locked or inval, it cannot 829 * partake in the clustered write. 830 */ 831 BO_LOCK(bo); 832 if ((tbp = gbincore(&vp->v_bufobj, start_lbn)) == NULL || 833 (tbp->b_vflags & BV_BKGRDINPROG)) { 834 BO_UNLOCK(bo); 835 ++start_lbn; 836 --len; 837 continue; 838 } 839 if (BUF_LOCK(tbp, 840 LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, BO_LOCKPTR(bo))) { 841 ++start_lbn; 842 --len; 843 continue; 844 } 845 if ((tbp->b_flags & (B_INVAL | B_DELWRI)) != B_DELWRI) { 846 BUF_UNLOCK(tbp); 847 ++start_lbn; 848 --len; 849 continue; 850 } 851 bremfree(tbp); 852 tbp->b_flags &= ~B_DONE; 853 854 /* 855 * Extra memory in the buffer, punt on this buffer. 856 * XXX we could handle this in most cases, but we would 857 * have to push the extra memory down to after our max 858 * possible cluster size and then potentially pull it back 859 * up if the cluster was terminated prematurely--too much 860 * hassle. 861 */ 862 if (((tbp->b_flags & (B_CLUSTEROK | B_MALLOC | B_VMIO)) != 863 (B_CLUSTEROK | B_VMIO)) || 864 (tbp->b_bcount != tbp->b_bufsize) || 865 (tbp->b_bcount != size) || 866 (len == 1) || 867 ((bp = uma_zalloc(cluster_pbuf_zone, M_NOWAIT)) == NULL)) { 868 totalwritten += tbp->b_bufsize; 869 bawrite(tbp); 870 ++start_lbn; 871 --len; 872 continue; 873 } 874 875 /* 876 * We got a pbuf to make the cluster in. 877 * so initialise it. 878 */ 879 TAILQ_INIT(&bp->b_cluster.cluster_head); 880 bp->b_bcount = 0; 881 bp->b_bufsize = 0; 882 bp->b_npages = 0; 883 if (tbp->b_wcred != NOCRED) 884 bp->b_wcred = crhold(tbp->b_wcred); 885 886 bp->b_blkno = tbp->b_blkno; 887 bp->b_lblkno = tbp->b_lblkno; 888 bp->b_offset = tbp->b_offset; 889 890 /* 891 * We are synthesizing a buffer out of vm_page_t's, but 892 * if the block size is not page aligned then the starting 893 * address may not be either. Inherit the b_data offset 894 * from the original buffer. 895 */ 896 if ((gbflags & GB_UNMAPPED) == 0 || 897 (tbp->b_flags & B_VMIO) == 0) { 898 bp->b_data = (char *)((vm_offset_t)bp->b_data | 899 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 900 } else { 901 bp->b_data = unmapped_buf; 902 } 903 bp->b_flags |= B_CLUSTER | (tbp->b_flags & (B_VMIO | 904 B_NEEDCOMMIT)); 905 bp->b_iodone = cluster_callback; 906 pbgetvp(vp, bp); 907 /* 908 * From this location in the file, scan forward to see 909 * if there are buffers with adjacent data that need to 910 * be written as well. 911 */ 912 for (i = 0; i < len; ++i, ++start_lbn) { 913 if (i != 0) { /* If not the first buffer */ 914 /* 915 * If the adjacent data is not even in core it 916 * can't need to be written. 917 */ 918 BO_LOCK(bo); 919 if ((tbp = gbincore(bo, start_lbn)) == NULL || 920 (tbp->b_vflags & BV_BKGRDINPROG)) { 921 BO_UNLOCK(bo); 922 break; 923 } 924 925 /* 926 * If it IS in core, but has different 927 * characteristics, or is locked (which 928 * means it could be undergoing a background 929 * I/O or be in a weird state), then don't 930 * cluster with it. 931 */ 932 if (BUF_LOCK(tbp, 933 LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, 934 BO_LOCKPTR(bo))) 935 break; 936 937 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK | 938 B_INVAL | B_DELWRI | B_NEEDCOMMIT)) 939 != (B_DELWRI | B_CLUSTEROK | 940 (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) || 941 tbp->b_wcred != bp->b_wcred) { 942 BUF_UNLOCK(tbp); 943 break; 944 } 945 946 /* 947 * Check that the combined cluster 948 * would make sense with regard to pages 949 * and would not be too large 950 */ 951 if ((tbp->b_bcount != size) || 952 ((bp->b_blkno + (dbsize * i)) != 953 tbp->b_blkno) || 954 ((tbp->b_npages + bp->b_npages) > 955 (vp->v_mount->mnt_iosize_max / PAGE_SIZE))) { 956 BUF_UNLOCK(tbp); 957 break; 958 } 959 960 /* 961 * Ok, it's passed all the tests, 962 * so remove it from the free list 963 * and mark it busy. We will use it. 964 */ 965 bremfree(tbp); 966 tbp->b_flags &= ~B_DONE; 967 } /* end of code for non-first buffers only */ 968 /* 969 * If the IO is via the VM then we do some 970 * special VM hackery (yuck). Since the buffer's 971 * block size may not be page-aligned it is possible 972 * for a page to be shared between two buffers. We 973 * have to get rid of the duplication when building 974 * the cluster. 975 */ 976 if (tbp->b_flags & B_VMIO) { 977 vm_page_t m; 978 979 if (i == 0) { 980 vfs_busy_pages_acquire(tbp); 981 } else { /* if not first buffer */ 982 for (j = 0; j < tbp->b_npages; j += 1) { 983 m = tbp->b_pages[j]; 984 if (vm_page_trysbusy(m) == 0) { 985 for (j--; j >= 0; j--) 986 vm_page_sunbusy( 987 tbp->b_pages[j]); 988 bqrelse(tbp); 989 goto finishcluster; 990 } 991 } 992 } 993 vm_object_pip_add(tbp->b_bufobj->bo_object, 994 tbp->b_npages); 995 for (j = 0; j < tbp->b_npages; j += 1) { 996 m = tbp->b_pages[j]; 997 if ((bp->b_npages == 0) || 998 (bp->b_pages[bp->b_npages - 1] != m)) { 999 bp->b_pages[bp->b_npages] = m; 1000 bp->b_npages++; 1001 } 1002 } 1003 } 1004 bp->b_bcount += size; 1005 bp->b_bufsize += size; 1006 /* 1007 * If any of the clustered buffers have their 1008 * B_BARRIER flag set, transfer that request to 1009 * the cluster. 1010 */ 1011 bp->b_flags |= (tbp->b_flags & B_BARRIER); 1012 tbp->b_flags &= ~(B_DONE | B_BARRIER); 1013 tbp->b_flags |= B_ASYNC; 1014 tbp->b_ioflags &= ~BIO_ERROR; 1015 tbp->b_iocmd = BIO_WRITE; 1016 bundirty(tbp); 1017 reassignbuf(tbp); /* put on clean list */ 1018 bufobj_wref(tbp->b_bufobj); 1019 BUF_KERNPROC(tbp); 1020 buf_track(tbp, __func__); 1021 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head, 1022 tbp, b_cluster.cluster_entry); 1023 } 1024 finishcluster: 1025 if (buf_mapped(bp)) { 1026 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 1027 (vm_page_t *)bp->b_pages, bp->b_npages); 1028 } 1029 if (bp->b_bufsize > bp->b_kvasize) 1030 panic( 1031 "cluster_wbuild: b_bufsize(%ld) > b_kvasize(%d)\n", 1032 bp->b_bufsize, bp->b_kvasize); 1033 totalwritten += bp->b_bufsize; 1034 bp->b_dirtyoff = 0; 1035 bp->b_dirtyend = bp->b_bufsize; 1036 bawrite(bp); 1037 1038 len -= i; 1039 } 1040 return totalwritten; 1041 } 1042 1043 /* 1044 * Collect together all the buffers in a cluster. 1045 * Plus add one additional buffer. 1046 */ 1047 static struct cluster_save * 1048 cluster_collectbufs(struct vnode *vp, struct buf *last_bp, int gbflags) 1049 { 1050 struct cluster_save *buflist; 1051 struct buf *bp; 1052 daddr_t lbn; 1053 int i, j, len, error; 1054 1055 len = vp->v_lastw - vp->v_cstart + 1; 1056 buflist = malloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist), 1057 M_SEGMENT, M_WAITOK); 1058 buflist->bs_nchildren = 0; 1059 buflist->bs_children = (struct buf **) (buflist + 1); 1060 for (lbn = vp->v_cstart, i = 0; i < len; lbn++, i++) { 1061 error = bread_gb(vp, lbn, last_bp->b_bcount, NOCRED, 1062 gbflags, &bp); 1063 if (error != 0) { 1064 /* 1065 * If read fails, release collected buffers 1066 * and return failure. 1067 */ 1068 for (j = 0; j < i; j++) 1069 brelse(buflist->bs_children[j]); 1070 free(buflist, M_SEGMENT); 1071 return (NULL); 1072 } 1073 buflist->bs_children[i] = bp; 1074 if (bp->b_blkno == bp->b_lblkno) 1075 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, 1076 NULL, NULL); 1077 } 1078 buflist->bs_children[i] = bp = last_bp; 1079 if (bp->b_blkno == bp->b_lblkno) 1080 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 1081 buflist->bs_nchildren = i + 1; 1082 return (buflist); 1083 } 1084