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sys/kern/vfs_cluster.c
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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 MPASS((bp->b_flags & B_MAXPHYS) != 0); 390 391 /* 392 * We are synthesizing a buffer out of vm_page_t's, but 393 * if the block size is not page aligned then the starting 394 * address may not be either. Inherit the b_data offset 395 * from the original buffer. 396 */ 397 bp->b_flags = B_ASYNC | B_CLUSTER | B_VMIO; 398 if ((gbflags & GB_UNMAPPED) != 0) { 399 bp->b_data = unmapped_buf; 400 } else { 401 bp->b_data = (char *)((vm_offset_t)bp->b_data | 402 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 403 } 404 bp->b_iocmd = BIO_READ; 405 bp->b_iodone = cluster_callback; 406 bp->b_blkno = blkno; 407 bp->b_lblkno = lbn; 408 bp->b_offset = tbp->b_offset; 409 KASSERT(bp->b_offset != NOOFFSET, ("cluster_rbuild: no buffer offset")); 410 pbgetvp(vp, bp); 411 412 TAILQ_INIT(&bp->b_cluster.cluster_head); 413 414 bp->b_bcount = 0; 415 bp->b_bufsize = 0; 416 bp->b_npages = 0; 417 418 inc = btodb(size); 419 for (bn = blkno, i = 0; i < run; ++i, bn += inc) { 420 if (i == 0) { 421 vm_object_pip_add(tbp->b_bufobj->bo_object, 422 tbp->b_npages); 423 vfs_busy_pages_acquire(tbp); 424 } else { 425 if ((bp->b_npages * PAGE_SIZE) + 426 round_page(size) > vp->v_mount->mnt_iosize_max) { 427 break; 428 } 429 430 tbp = getblk(vp, lbn + i, size, 0, 0, GB_LOCK_NOWAIT | 431 (gbflags & GB_UNMAPPED)); 432 433 /* Don't wait around for locked bufs. */ 434 if (tbp == NULL) 435 break; 436 437 /* 438 * Stop scanning if the buffer is fully valid 439 * (marked B_CACHE), or locked (may be doing a 440 * background write), or if the buffer is not 441 * VMIO backed. The clustering code can only deal 442 * with VMIO-backed buffers. The bo lock is not 443 * required for the BKGRDINPROG check since it 444 * can not be set without the buf lock. 445 */ 446 if ((tbp->b_vflags & BV_BKGRDINPROG) || 447 (tbp->b_flags & B_CACHE) || 448 (tbp->b_flags & B_VMIO) == 0) { 449 bqrelse(tbp); 450 break; 451 } 452 453 /* 454 * The buffer must be completely invalid in order to 455 * take part in the cluster. If it is partially valid 456 * then we stop. 457 */ 458 off = tbp->b_offset; 459 tsize = size; 460 for (j = 0; tsize > 0; j++) { 461 toff = off & PAGE_MASK; 462 tinc = tsize; 463 if (toff + tinc > PAGE_SIZE) 464 tinc = PAGE_SIZE - toff; 465 if (vm_page_trysbusy(tbp->b_pages[j]) == 0) 466 break; 467 if ((tbp->b_pages[j]->valid & 468 vm_page_bits(toff, tinc)) != 0) { 469 vm_page_sunbusy(tbp->b_pages[j]); 470 break; 471 } 472 vm_object_pip_add(tbp->b_bufobj->bo_object, 1); 473 off += tinc; 474 tsize -= tinc; 475 } 476 if (tsize > 0) { 477 clean_sbusy: 478 vm_object_pip_wakeupn(tbp->b_bufobj->bo_object, 479 j); 480 for (k = 0; k < j; k++) 481 vm_page_sunbusy(tbp->b_pages[k]); 482 bqrelse(tbp); 483 break; 484 } 485 486 /* 487 * Set a read-ahead mark as appropriate 488 */ 489 if ((fbp && (i == 1)) || (i == (run - 1))) 490 tbp->b_flags |= B_RAM; 491 492 /* 493 * Set the buffer up for an async read (XXX should 494 * we do this only if we do not wind up brelse()ing?). 495 * Set the block number if it isn't set, otherwise 496 * if it is make sure it matches the block number we 497 * expect. 498 */ 499 tbp->b_flags |= B_ASYNC; 500 tbp->b_iocmd = BIO_READ; 501 if (tbp->b_blkno == tbp->b_lblkno) { 502 tbp->b_blkno = bn; 503 } else if (tbp->b_blkno != bn) { 504 goto clean_sbusy; 505 } 506 } 507 /* 508 * XXX fbp from caller may not be B_ASYNC, but we are going 509 * to biodone() it in cluster_callback() anyway 510 */ 511 BUF_KERNPROC(tbp); 512 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head, 513 tbp, b_cluster.cluster_entry); 514 for (j = 0; j < tbp->b_npages; j += 1) { 515 vm_page_t m; 516 517 m = tbp->b_pages[j]; 518 if ((bp->b_npages == 0) || 519 (bp->b_pages[bp->b_npages-1] != m)) { 520 bp->b_pages[bp->b_npages] = m; 521 bp->b_npages++; 522 } 523 if (vm_page_all_valid(m)) 524 tbp->b_pages[j] = bogus_page; 525 } 526 527 /* 528 * Don't inherit tbp->b_bufsize as it may be larger due to 529 * a non-page-aligned size. Instead just aggregate using 530 * 'size'. 531 */ 532 if (tbp->b_bcount != size) 533 printf("warning: tbp->b_bcount wrong %ld vs %ld\n", tbp->b_bcount, size); 534 if (tbp->b_bufsize != size) 535 printf("warning: tbp->b_bufsize wrong %ld vs %ld\n", tbp->b_bufsize, size); 536 bp->b_bcount += size; 537 bp->b_bufsize += size; 538 } 539 540 /* 541 * Fully valid pages in the cluster are already good and do not need 542 * to be re-read from disk. Replace the page with bogus_page 543 */ 544 for (j = 0; j < bp->b_npages; j++) { 545 if (vm_page_all_valid(bp->b_pages[j])) 546 bp->b_pages[j] = bogus_page; 547 } 548 if (bp->b_bufsize > bp->b_kvasize) 549 panic("cluster_rbuild: b_bufsize(%ld) > b_kvasize(%d)\n", 550 bp->b_bufsize, bp->b_kvasize); 551 552 if (buf_mapped(bp)) { 553 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 554 (vm_page_t *)bp->b_pages, bp->b_npages); 555 } 556 return (bp); 557 } 558 559 /* 560 * Cleanup after a clustered read or write. 561 * This is complicated by the fact that any of the buffers might have 562 * extra memory (if there were no empty buffer headers at allocbuf time) 563 * that we will need to shift around. 564 */ 565 static void 566 cluster_callback(struct buf *bp) 567 { 568 struct buf *nbp, *tbp; 569 int error = 0; 570 571 /* 572 * Must propagate errors to all the components. 573 */ 574 if (bp->b_ioflags & BIO_ERROR) 575 error = bp->b_error; 576 577 if (buf_mapped(bp)) { 578 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), 579 bp->b_npages); 580 } 581 /* 582 * Move memory from the large cluster buffer into the component 583 * buffers and mark IO as done on these. 584 */ 585 for (tbp = TAILQ_FIRST(&bp->b_cluster.cluster_head); 586 tbp; tbp = nbp) { 587 nbp = TAILQ_NEXT(&tbp->b_cluster, cluster_entry); 588 if (error) { 589 tbp->b_ioflags |= BIO_ERROR; 590 tbp->b_error = error; 591 } else { 592 tbp->b_dirtyoff = tbp->b_dirtyend = 0; 593 tbp->b_flags &= ~B_INVAL; 594 tbp->b_ioflags &= ~BIO_ERROR; 595 /* 596 * XXX the bdwrite()/bqrelse() issued during 597 * cluster building clears B_RELBUF (see bqrelse() 598 * comment). If direct I/O was specified, we have 599 * to restore it here to allow the buffer and VM 600 * to be freed. 601 */ 602 if (tbp->b_flags & B_DIRECT) 603 tbp->b_flags |= B_RELBUF; 604 } 605 bufdone(tbp); 606 } 607 pbrelvp(bp); 608 uma_zfree(cluster_pbuf_zone, bp); 609 } 610 611 /* 612 * cluster_wbuild_wb: 613 * 614 * Implement modified write build for cluster. 615 * 616 * write_behind = 0 write behind disabled 617 * write_behind = 1 write behind normal (default) 618 * write_behind = 2 write behind backed-off 619 */ 620 621 static __inline int 622 cluster_wbuild_wb(struct vnode *vp, long size, daddr_t start_lbn, int len, 623 int gbflags) 624 { 625 int r = 0; 626 627 switch (write_behind) { 628 case 2: 629 if (start_lbn < len) 630 break; 631 start_lbn -= len; 632 /* FALLTHROUGH */ 633 case 1: 634 r = cluster_wbuild(vp, size, start_lbn, len, gbflags); 635 /* FALLTHROUGH */ 636 default: 637 /* FALLTHROUGH */ 638 break; 639 } 640 return(r); 641 } 642 643 /* 644 * Do clustered write for FFS. 645 * 646 * Three cases: 647 * 1. Write is not sequential (write asynchronously) 648 * Write is sequential: 649 * 2. beginning of cluster - begin cluster 650 * 3. middle of a cluster - add to cluster 651 * 4. end of a cluster - asynchronously write cluster 652 */ 653 void 654 cluster_write(struct vnode *vp, struct buf *bp, u_quad_t filesize, int seqcount, 655 int gbflags) 656 { 657 daddr_t lbn; 658 int maxclen, cursize; 659 int lblocksize; 660 int async; 661 662 if (!unmapped_buf_allowed) 663 gbflags &= ~GB_UNMAPPED; 664 665 if (vp->v_type == VREG) { 666 async = DOINGASYNC(vp); 667 lblocksize = vp->v_mount->mnt_stat.f_iosize; 668 } else { 669 async = 0; 670 lblocksize = bp->b_bufsize; 671 } 672 lbn = bp->b_lblkno; 673 KASSERT(bp->b_offset != NOOFFSET, ("cluster_write: no buffer offset")); 674 675 /* Initialize vnode to beginning of file. */ 676 if (lbn == 0) 677 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0; 678 679 if (vp->v_clen == 0 || lbn != vp->v_lastw + 1 || 680 (bp->b_blkno != vp->v_lasta + btodb(lblocksize))) { 681 maxclen = vp->v_mount->mnt_iosize_max / lblocksize - 1; 682 if (vp->v_clen != 0) { 683 /* 684 * Next block is not sequential. 685 * 686 * If we are not writing at end of file, the process 687 * seeked to another point in the file since its last 688 * write, or we have reached our maximum cluster size, 689 * then push the previous cluster. Otherwise try 690 * reallocating to make it sequential. 691 * 692 * Change to algorithm: only push previous cluster if 693 * it was sequential from the point of view of the 694 * seqcount heuristic, otherwise leave the buffer 695 * intact so we can potentially optimize the I/O 696 * later on in the buf_daemon or update daemon 697 * flush. 698 */ 699 cursize = vp->v_lastw - vp->v_cstart + 1; 700 if (((u_quad_t) bp->b_offset + lblocksize) != filesize || 701 lbn != vp->v_lastw + 1 || vp->v_clen <= cursize) { 702 if (!async && seqcount > 0) { 703 cluster_wbuild_wb(vp, lblocksize, 704 vp->v_cstart, cursize, gbflags); 705 } 706 } else { 707 struct buf **bpp, **endbp; 708 struct cluster_save *buflist; 709 710 buflist = cluster_collectbufs(vp, bp, gbflags); 711 if (buflist == NULL) { 712 /* 713 * Cluster build failed so just write 714 * it now. 715 */ 716 bawrite(bp); 717 return; 718 } 719 endbp = &buflist->bs_children 720 [buflist->bs_nchildren - 1]; 721 if (VOP_REALLOCBLKS(vp, buflist)) { 722 /* 723 * Failed, push the previous cluster 724 * if *really* writing sequentially 725 * in the logical file (seqcount > 1), 726 * otherwise delay it in the hopes that 727 * the low level disk driver can 728 * optimize the write ordering. 729 */ 730 for (bpp = buflist->bs_children; 731 bpp < endbp; bpp++) 732 brelse(*bpp); 733 free(buflist, M_SEGMENT); 734 if (seqcount > 1) { 735 cluster_wbuild_wb(vp, 736 lblocksize, vp->v_cstart, 737 cursize, gbflags); 738 } 739 } else { 740 /* 741 * Succeeded, keep building cluster. 742 */ 743 for (bpp = buflist->bs_children; 744 bpp <= endbp; bpp++) 745 bdwrite(*bpp); 746 free(buflist, M_SEGMENT); 747 vp->v_lastw = lbn; 748 vp->v_lasta = bp->b_blkno; 749 return; 750 } 751 } 752 } 753 /* 754 * Consider beginning a cluster. If at end of file, make 755 * cluster as large as possible, otherwise find size of 756 * existing cluster. 757 */ 758 if ((vp->v_type == VREG) && 759 ((u_quad_t) bp->b_offset + lblocksize) != filesize && 760 (bp->b_blkno == bp->b_lblkno) && 761 (VOP_BMAP(vp, lbn, NULL, &bp->b_blkno, &maxclen, NULL) || 762 bp->b_blkno == -1)) { 763 bawrite(bp); 764 vp->v_clen = 0; 765 vp->v_lasta = bp->b_blkno; 766 vp->v_cstart = lbn + 1; 767 vp->v_lastw = lbn; 768 return; 769 } 770 vp->v_clen = maxclen; 771 if (!async && maxclen == 0) { /* I/O not contiguous */ 772 vp->v_cstart = lbn + 1; 773 bawrite(bp); 774 } else { /* Wait for rest of cluster */ 775 vp->v_cstart = lbn; 776 bdwrite(bp); 777 } 778 } else if (lbn == vp->v_cstart + vp->v_clen) { 779 /* 780 * At end of cluster, write it out if seqcount tells us we 781 * are operating sequentially, otherwise let the buf or 782 * update daemon handle it. 783 */ 784 bdwrite(bp); 785 if (seqcount > 1) { 786 cluster_wbuild_wb(vp, lblocksize, vp->v_cstart, 787 vp->v_clen + 1, gbflags); 788 } 789 vp->v_clen = 0; 790 vp->v_cstart = lbn + 1; 791 } else if (vm_page_count_severe()) { 792 /* 793 * We are low on memory, get it going NOW 794 */ 795 bawrite(bp); 796 } else { 797 /* 798 * In the middle of a cluster, so just delay the I/O for now. 799 */ 800 bdwrite(bp); 801 } 802 vp->v_lastw = lbn; 803 vp->v_lasta = bp->b_blkno; 804 } 805 806 /* 807 * This is an awful lot like cluster_rbuild...wish they could be combined. 808 * The last lbn argument is the current block on which I/O is being 809 * performed. Check to see that it doesn't fall in the middle of 810 * the current block (if last_bp == NULL). 811 */ 812 int 813 cluster_wbuild(struct vnode *vp, long size, daddr_t start_lbn, int len, 814 int gbflags) 815 { 816 struct buf *bp, *tbp; 817 struct bufobj *bo; 818 int i, j; 819 int totalwritten = 0; 820 int dbsize = btodb(size); 821 822 if (!unmapped_buf_allowed) 823 gbflags &= ~GB_UNMAPPED; 824 825 bo = &vp->v_bufobj; 826 while (len > 0) { 827 /* 828 * If the buffer is not delayed-write (i.e. dirty), or it 829 * is delayed-write but either locked or inval, it cannot 830 * partake in the clustered write. 831 */ 832 BO_LOCK(bo); 833 if ((tbp = gbincore(&vp->v_bufobj, start_lbn)) == NULL || 834 (tbp->b_vflags & BV_BKGRDINPROG)) { 835 BO_UNLOCK(bo); 836 ++start_lbn; 837 --len; 838 continue; 839 } 840 if (BUF_LOCK(tbp, 841 LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, BO_LOCKPTR(bo))) { 842 ++start_lbn; 843 --len; 844 continue; 845 } 846 if ((tbp->b_flags & (B_INVAL | B_DELWRI)) != B_DELWRI) { 847 BUF_UNLOCK(tbp); 848 ++start_lbn; 849 --len; 850 continue; 851 } 852 bremfree(tbp); 853 tbp->b_flags &= ~B_DONE; 854 855 /* 856 * Extra memory in the buffer, punt on this buffer. 857 * XXX we could handle this in most cases, but we would 858 * have to push the extra memory down to after our max 859 * possible cluster size and then potentially pull it back 860 * up if the cluster was terminated prematurely--too much 861 * hassle. 862 */ 863 if (((tbp->b_flags & (B_CLUSTEROK | B_MALLOC | B_VMIO)) != 864 (B_CLUSTEROK | B_VMIO)) || 865 (tbp->b_bcount != tbp->b_bufsize) || 866 (tbp->b_bcount != size) || 867 (len == 1) || 868 ((bp = uma_zalloc(cluster_pbuf_zone, M_NOWAIT)) == NULL)) { 869 totalwritten += tbp->b_bufsize; 870 bawrite(tbp); 871 ++start_lbn; 872 --len; 873 continue; 874 } 875 MPASS((bp->b_flags & B_MAXPHYS) != 0); 876 877 /* 878 * We got a pbuf to make the cluster in. 879 * so initialise it. 880 */ 881 TAILQ_INIT(&bp->b_cluster.cluster_head); 882 bp->b_bcount = 0; 883 bp->b_bufsize = 0; 884 bp->b_npages = 0; 885 if (tbp->b_wcred != NOCRED) 886 bp->b_wcred = crhold(tbp->b_wcred); 887 888 bp->b_blkno = tbp->b_blkno; 889 bp->b_lblkno = tbp->b_lblkno; 890 bp->b_offset = tbp->b_offset; 891 892 /* 893 * We are synthesizing a buffer out of vm_page_t's, but 894 * if the block size is not page aligned then the starting 895 * address may not be either. Inherit the b_data offset 896 * from the original buffer. 897 */ 898 if ((gbflags & GB_UNMAPPED) == 0 || 899 (tbp->b_flags & B_VMIO) == 0) { 900 bp->b_data = (char *)((vm_offset_t)bp->b_data | 901 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 902 } else { 903 bp->b_data = unmapped_buf; 904 } 905 bp->b_flags |= B_CLUSTER | (tbp->b_flags & (B_VMIO | 906 B_NEEDCOMMIT)); 907 bp->b_iodone = cluster_callback; 908 pbgetvp(vp, bp); 909 /* 910 * From this location in the file, scan forward to see 911 * if there are buffers with adjacent data that need to 912 * be written as well. 913 */ 914 for (i = 0; i < len; ++i, ++start_lbn) { 915 if (i != 0) { /* If not the first buffer */ 916 /* 917 * If the adjacent data is not even in core it 918 * can't need to be written. 919 */ 920 BO_LOCK(bo); 921 if ((tbp = gbincore(bo, start_lbn)) == NULL || 922 (tbp->b_vflags & BV_BKGRDINPROG)) { 923 BO_UNLOCK(bo); 924 break; 925 } 926 927 /* 928 * If it IS in core, but has different 929 * characteristics, or is locked (which 930 * means it could be undergoing a background 931 * I/O or be in a weird state), then don't 932 * cluster with it. 933 */ 934 if (BUF_LOCK(tbp, 935 LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, 936 BO_LOCKPTR(bo))) 937 break; 938 939 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK | 940 B_INVAL | B_DELWRI | B_NEEDCOMMIT)) 941 != (B_DELWRI | B_CLUSTEROK | 942 (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) || 943 tbp->b_wcred != bp->b_wcred) { 944 BUF_UNLOCK(tbp); 945 break; 946 } 947 948 /* 949 * Check that the combined cluster 950 * would make sense with regard to pages 951 * and would not be too large 952 */ 953 if ((tbp->b_bcount != size) || 954 ((bp->b_blkno + (dbsize * i)) != 955 tbp->b_blkno) || 956 ((tbp->b_npages + bp->b_npages) > 957 (vp->v_mount->mnt_iosize_max / PAGE_SIZE))) { 958 BUF_UNLOCK(tbp); 959 break; 960 } 961 962 /* 963 * Ok, it's passed all the tests, 964 * so remove it from the free list 965 * and mark it busy. We will use it. 966 */ 967 bremfree(tbp); 968 tbp->b_flags &= ~B_DONE; 969 } /* end of code for non-first buffers only */ 970 /* 971 * If the IO is via the VM then we do some 972 * special VM hackery (yuck). Since the buffer's 973 * block size may not be page-aligned it is possible 974 * for a page to be shared between two buffers. We 975 * have to get rid of the duplication when building 976 * the cluster. 977 */ 978 if (tbp->b_flags & B_VMIO) { 979 vm_page_t m; 980 981 if (i == 0) { 982 vfs_busy_pages_acquire(tbp); 983 } else { /* if not first buffer */ 984 for (j = 0; j < tbp->b_npages; j += 1) { 985 m = tbp->b_pages[j]; 986 if (vm_page_trysbusy(m) == 0) { 987 for (j--; j >= 0; j--) 988 vm_page_sunbusy( 989 tbp->b_pages[j]); 990 bqrelse(tbp); 991 goto finishcluster; 992 } 993 } 994 } 995 vm_object_pip_add(tbp->b_bufobj->bo_object, 996 tbp->b_npages); 997 for (j = 0; j < tbp->b_npages; j += 1) { 998 m = tbp->b_pages[j]; 999 if ((bp->b_npages == 0) || 1000 (bp->b_pages[bp->b_npages - 1] != m)) { 1001 bp->b_pages[bp->b_npages] = m; 1002 bp->b_npages++; 1003 } 1004 } 1005 } 1006 bp->b_bcount += size; 1007 bp->b_bufsize += size; 1008 /* 1009 * If any of the clustered buffers have their 1010 * B_BARRIER flag set, transfer that request to 1011 * the cluster. 1012 */ 1013 bp->b_flags |= (tbp->b_flags & B_BARRIER); 1014 tbp->b_flags &= ~(B_DONE | B_BARRIER); 1015 tbp->b_flags |= B_ASYNC; 1016 tbp->b_ioflags &= ~BIO_ERROR; 1017 tbp->b_iocmd = BIO_WRITE; 1018 bundirty(tbp); 1019 reassignbuf(tbp); /* put on clean list */ 1020 bufobj_wref(tbp->b_bufobj); 1021 BUF_KERNPROC(tbp); 1022 buf_track(tbp, __func__); 1023 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head, 1024 tbp, b_cluster.cluster_entry); 1025 } 1026 finishcluster: 1027 if (buf_mapped(bp)) { 1028 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 1029 (vm_page_t *)bp->b_pages, bp->b_npages); 1030 } 1031 if (bp->b_bufsize > bp->b_kvasize) 1032 panic( 1033 "cluster_wbuild: b_bufsize(%ld) > b_kvasize(%d)\n", 1034 bp->b_bufsize, bp->b_kvasize); 1035 totalwritten += bp->b_bufsize; 1036 bp->b_dirtyoff = 0; 1037 bp->b_dirtyend = bp->b_bufsize; 1038 bawrite(bp); 1039 1040 len -= i; 1041 } 1042 return totalwritten; 1043 } 1044 1045 /* 1046 * Collect together all the buffers in a cluster. 1047 * Plus add one additional buffer. 1048 */ 1049 static struct cluster_save * 1050 cluster_collectbufs(struct vnode *vp, struct buf *last_bp, int gbflags) 1051 { 1052 struct cluster_save *buflist; 1053 struct buf *bp; 1054 daddr_t lbn; 1055 int i, j, len, error; 1056 1057 len = vp->v_lastw - vp->v_cstart + 1; 1058 buflist = malloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist), 1059 M_SEGMENT, M_WAITOK); 1060 buflist->bs_nchildren = 0; 1061 buflist->bs_children = (struct buf **) (buflist + 1); 1062 for (lbn = vp->v_cstart, i = 0; i < len; lbn++, i++) { 1063 error = bread_gb(vp, lbn, last_bp->b_bcount, NOCRED, 1064 gbflags, &bp); 1065 if (error != 0) { 1066 /* 1067 * If read fails, release collected buffers 1068 * and return failure. 1069 */ 1070 for (j = 0; j < i; j++) 1071 brelse(buflist->bs_children[j]); 1072 free(buflist, M_SEGMENT); 1073 return (NULL); 1074 } 1075 buflist->bs_children[i] = bp; 1076 if (bp->b_blkno == bp->b_lblkno) 1077 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, 1078 NULL, NULL); 1079 } 1080 buflist->bs_children[i] = bp = last_bp; 1081 if (bp->b_blkno == bp->b_lblkno) 1082 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 1083 buflist->bs_nchildren = i + 1; 1084 return (buflist); 1085 }
Cache object: 1b21edda8fc120b85dbb46b263a76cbb
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