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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 <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/racct.h> 49 #include <sys/resourcevar.h> 50 #include <sys/rwlock.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 57 static MALLOC_DEFINE(M_SEGMENT, "cl_savebuf", "cluster_save buffer"); 58 static uma_zone_t cluster_pbuf_zone; 59 60 static void cluster_init(void *); 61 static struct cluster_save *cluster_collectbufs(struct vnode *vp, 62 struct buf *last_bp, int gbflags); 63 static struct buf *cluster_rbuild(struct vnode *vp, u_quad_t filesize, 64 daddr_t lbn, daddr_t blkno, long size, int run, int gbflags, 65 struct buf *fbp); 66 static void cluster_callback(struct buf *); 67 68 static int write_behind = 1; 69 SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0, 70 "Cluster write-behind; 0: disable, 1: enable, 2: backed off"); 71 72 static int read_max = 64; 73 SYSCTL_INT(_vfs, OID_AUTO, read_max, CTLFLAG_RW, &read_max, 0, 74 "Cluster read-ahead max block count"); 75 76 static int read_min = 1; 77 SYSCTL_INT(_vfs, OID_AUTO, read_min, CTLFLAG_RW, &read_min, 0, 78 "Cluster read min block count"); 79 80 SYSINIT(cluster, SI_SUB_CPU, SI_ORDER_ANY, cluster_init, NULL); 81 82 static void 83 cluster_init(void *dummy) 84 { 85 86 cluster_pbuf_zone = pbuf_zsecond_create("clpbuf", nswbuf / 2); 87 } 88 89 /* 90 * Read data to a buf, including read-ahead if we find this to be beneficial. 91 * cluster_read replaces bread. 92 */ 93 int 94 cluster_read(struct vnode *vp, u_quad_t filesize, daddr_t lblkno, long size, 95 struct ucred *cred, long totread, int seqcount, int gbflags, 96 struct buf **bpp) 97 { 98 struct buf *bp, *rbp, *reqbp; 99 struct bufobj *bo; 100 struct thread *td; 101 daddr_t blkno, origblkno; 102 int maxra, racluster; 103 int error, ncontig; 104 int i; 105 106 error = 0; 107 td = curthread; 108 bo = &vp->v_bufobj; 109 if (!unmapped_buf_allowed) 110 gbflags &= ~GB_UNMAPPED; 111 112 /* 113 * Try to limit the amount of read-ahead by a few 114 * ad-hoc parameters. This needs work!!! 115 */ 116 racluster = vp->v_mount->mnt_iosize_max / size; 117 maxra = seqcount; 118 maxra = min(read_max, maxra); 119 maxra = min(nbuf/8, maxra); 120 if (((u_quad_t)(lblkno + maxra + 1) * size) > filesize) 121 maxra = (filesize / size) - lblkno; 122 123 /* 124 * get the requested block 125 */ 126 error = getblkx(vp, lblkno, lblkno, size, 0, 0, gbflags, &bp); 127 if (error != 0) { 128 *bpp = NULL; 129 return (error); 130 } 131 gbflags &= ~GB_NOSPARSE; 132 origblkno = lblkno; 133 *bpp = reqbp = bp; 134 135 /* 136 * if it is in the cache, then check to see if the reads have been 137 * sequential. If they have, then try some read-ahead, otherwise 138 * back-off on prospective read-aheads. 139 */ 140 if (bp->b_flags & B_CACHE) { 141 if (!seqcount) { 142 return 0; 143 } else if ((bp->b_flags & B_RAM) == 0) { 144 return 0; 145 } else { 146 bp->b_flags &= ~B_RAM; 147 BO_RLOCK(bo); 148 for (i = 1; i < maxra; i++) { 149 /* 150 * Stop if the buffer does not exist or it 151 * is invalid (about to go away?) 152 */ 153 rbp = gbincore(&vp->v_bufobj, lblkno+i); 154 if (rbp == NULL || (rbp->b_flags & B_INVAL)) 155 break; 156 157 /* 158 * Set another read-ahead mark so we know 159 * to check again. (If we can lock the 160 * buffer without waiting) 161 */ 162 if ((((i % racluster) == (racluster - 1)) || 163 (i == (maxra - 1))) 164 && (0 == BUF_LOCK(rbp, 165 LK_EXCLUSIVE | LK_NOWAIT, NULL))) { 166 rbp->b_flags |= B_RAM; 167 BUF_UNLOCK(rbp); 168 } 169 } 170 BO_RUNLOCK(bo); 171 if (i >= maxra) { 172 return 0; 173 } 174 lblkno += i; 175 } 176 reqbp = bp = NULL; 177 /* 178 * If it isn't in the cache, then get a chunk from 179 * disk if sequential, otherwise just get the block. 180 */ 181 } else { 182 off_t firstread = bp->b_offset; 183 int nblks; 184 long minread; 185 186 KASSERT(bp->b_offset != NOOFFSET, 187 ("cluster_read: no buffer offset")); 188 189 ncontig = 0; 190 191 /* 192 * Adjust totread if needed 193 */ 194 minread = read_min * size; 195 if (minread > totread) 196 totread = minread; 197 198 /* 199 * Compute the total number of blocks that we should read 200 * synchronously. 201 */ 202 if (firstread + totread > filesize) 203 totread = filesize - firstread; 204 nblks = howmany(totread, size); 205 if (nblks > racluster) 206 nblks = racluster; 207 208 /* 209 * Now compute the number of contiguous blocks. 210 */ 211 if (nblks > 1) { 212 error = VOP_BMAP(vp, lblkno, NULL, 213 &blkno, &ncontig, NULL); 214 /* 215 * If this failed to map just do the original block. 216 */ 217 if (error || blkno == -1) 218 ncontig = 0; 219 } 220 221 /* 222 * If we have contiguous data available do a cluster 223 * otherwise just read the requested block. 224 */ 225 if (ncontig) { 226 /* Account for our first block. */ 227 ncontig = min(ncontig + 1, nblks); 228 if (ncontig < nblks) 229 nblks = ncontig; 230 bp = cluster_rbuild(vp, filesize, lblkno, 231 blkno, size, nblks, gbflags, bp); 232 lblkno += (bp->b_bufsize / size); 233 } else { 234 bp->b_flags |= B_RAM; 235 bp->b_iocmd = BIO_READ; 236 lblkno += 1; 237 } 238 } 239 240 /* 241 * handle the synchronous read so that it is available ASAP. 242 */ 243 if (bp) { 244 if ((bp->b_flags & B_CLUSTER) == 0) { 245 vfs_busy_pages(bp, 0); 246 } 247 bp->b_flags &= ~B_INVAL; 248 bp->b_ioflags &= ~BIO_ERROR; 249 if ((bp->b_flags & B_ASYNC) || bp->b_iodone != NULL) 250 BUF_KERNPROC(bp); 251 bp->b_iooffset = dbtob(bp->b_blkno); 252 bstrategy(bp); 253 #ifdef RACCT 254 if (racct_enable) { 255 PROC_LOCK(td->td_proc); 256 racct_add_buf(td->td_proc, bp, 0); 257 PROC_UNLOCK(td->td_proc); 258 } 259 #endif /* RACCT */ 260 td->td_ru.ru_inblock++; 261 } 262 263 /* 264 * If we have been doing sequential I/O, then do some read-ahead. 265 */ 266 while (lblkno < (origblkno + maxra)) { 267 error = VOP_BMAP(vp, lblkno, NULL, &blkno, &ncontig, NULL); 268 if (error) 269 break; 270 271 if (blkno == -1) 272 break; 273 274 /* 275 * We could throttle ncontig here by maxra but we might as 276 * well read the data if it is contiguous. We're throttled 277 * by racluster anyway. 278 */ 279 if (ncontig) { 280 ncontig = min(ncontig + 1, racluster); 281 rbp = cluster_rbuild(vp, filesize, lblkno, blkno, 282 size, ncontig, gbflags, NULL); 283 lblkno += (rbp->b_bufsize / size); 284 if (rbp->b_flags & B_DELWRI) { 285 bqrelse(rbp); 286 continue; 287 } 288 } else { 289 rbp = getblk(vp, lblkno, size, 0, 0, gbflags); 290 lblkno += 1; 291 if (rbp->b_flags & B_DELWRI) { 292 bqrelse(rbp); 293 continue; 294 } 295 rbp->b_flags |= B_ASYNC | B_RAM; 296 rbp->b_iocmd = BIO_READ; 297 rbp->b_blkno = blkno; 298 } 299 if (rbp->b_flags & B_CACHE) { 300 rbp->b_flags &= ~B_ASYNC; 301 bqrelse(rbp); 302 continue; 303 } 304 if ((rbp->b_flags & B_CLUSTER) == 0) { 305 vfs_busy_pages(rbp, 0); 306 } 307 rbp->b_flags &= ~B_INVAL; 308 rbp->b_ioflags &= ~BIO_ERROR; 309 if ((rbp->b_flags & B_ASYNC) || rbp->b_iodone != NULL) 310 BUF_KERNPROC(rbp); 311 rbp->b_iooffset = dbtob(rbp->b_blkno); 312 bstrategy(rbp); 313 #ifdef RACCT 314 if (racct_enable) { 315 PROC_LOCK(td->td_proc); 316 racct_add_buf(td->td_proc, rbp, 0); 317 PROC_UNLOCK(td->td_proc); 318 } 319 #endif /* RACCT */ 320 td->td_ru.ru_inblock++; 321 } 322 323 if (reqbp) { 324 /* 325 * Like bread, always brelse() the buffer when 326 * returning an error. 327 */ 328 error = bufwait(reqbp); 329 if (error != 0) { 330 brelse(reqbp); 331 *bpp = NULL; 332 } 333 } 334 return (error); 335 } 336 337 /* 338 * If blocks are contiguous on disk, use this to provide clustered 339 * read ahead. We will read as many blocks as possible sequentially 340 * and then parcel them up into logical blocks in the buffer hash table. 341 */ 342 static struct buf * 343 cluster_rbuild(struct vnode *vp, u_quad_t filesize, daddr_t lbn, 344 daddr_t blkno, long size, int run, int gbflags, struct buf *fbp) 345 { 346 struct buf *bp, *tbp; 347 daddr_t bn; 348 off_t off; 349 long tinc, tsize; 350 int i, inc, j, k, toff; 351 352 KASSERT(size == vp->v_mount->mnt_stat.f_iosize, 353 ("cluster_rbuild: size %ld != f_iosize %jd\n", 354 size, (intmax_t)vp->v_mount->mnt_stat.f_iosize)); 355 356 /* 357 * avoid a division 358 */ 359 while ((u_quad_t) size * (lbn + run) > filesize) { 360 --run; 361 } 362 363 if (fbp) { 364 tbp = fbp; 365 tbp->b_iocmd = BIO_READ; 366 } else { 367 tbp = getblk(vp, lbn, size, 0, 0, gbflags); 368 if (tbp->b_flags & B_CACHE) 369 return tbp; 370 tbp->b_flags |= B_ASYNC | B_RAM; 371 tbp->b_iocmd = BIO_READ; 372 } 373 tbp->b_blkno = blkno; 374 if( (tbp->b_flags & B_MALLOC) || 375 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1) ) 376 return tbp; 377 378 bp = uma_zalloc(cluster_pbuf_zone, M_NOWAIT); 379 if (bp == NULL) 380 return tbp; 381 MPASS((bp->b_flags & B_MAXPHYS) != 0); 382 383 /* 384 * We are synthesizing a buffer out of vm_page_t's, but 385 * if the block size is not page aligned then the starting 386 * address may not be either. Inherit the b_data offset 387 * from the original buffer. 388 */ 389 bp->b_flags = B_ASYNC | B_CLUSTER | B_VMIO; 390 if ((gbflags & GB_UNMAPPED) != 0) { 391 bp->b_data = unmapped_buf; 392 } else { 393 bp->b_data = (char *)((vm_offset_t)bp->b_data | 394 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 395 } 396 bp->b_iocmd = BIO_READ; 397 bp->b_iodone = cluster_callback; 398 bp->b_blkno = blkno; 399 bp->b_lblkno = lbn; 400 bp->b_offset = tbp->b_offset; 401 KASSERT(bp->b_offset != NOOFFSET, ("cluster_rbuild: no buffer offset")); 402 pbgetvp(vp, bp); 403 404 TAILQ_INIT(&bp->b_cluster.cluster_head); 405 406 bp->b_bcount = 0; 407 bp->b_bufsize = 0; 408 bp->b_npages = 0; 409 410 inc = btodb(size); 411 for (bn = blkno, i = 0; i < run; ++i, bn += inc) { 412 if (i == 0) { 413 vm_object_pip_add(tbp->b_bufobj->bo_object, 414 tbp->b_npages); 415 vfs_busy_pages_acquire(tbp); 416 } else { 417 if ((bp->b_npages * PAGE_SIZE) + 418 round_page(size) > vp->v_mount->mnt_iosize_max) { 419 break; 420 } 421 422 tbp = getblk(vp, lbn + i, size, 0, 0, GB_LOCK_NOWAIT | 423 (gbflags & GB_UNMAPPED)); 424 425 /* Don't wait around for locked bufs. */ 426 if (tbp == NULL) 427 break; 428 429 /* 430 * Stop scanning if the buffer is fully valid 431 * (marked B_CACHE), or locked (may be doing a 432 * background write), or if the buffer is not 433 * VMIO backed. The clustering code can only deal 434 * with VMIO-backed buffers. The bo lock is not 435 * required for the BKGRDINPROG check since it 436 * can not be set without the buf lock. 437 */ 438 if ((tbp->b_vflags & BV_BKGRDINPROG) || 439 (tbp->b_flags & B_CACHE) || 440 (tbp->b_flags & B_VMIO) == 0) { 441 bqrelse(tbp); 442 break; 443 } 444 445 /* 446 * The buffer must be completely invalid in order to 447 * take part in the cluster. If it is partially valid 448 * then we stop. 449 */ 450 off = tbp->b_offset; 451 tsize = size; 452 for (j = 0; tsize > 0; j++) { 453 toff = off & PAGE_MASK; 454 tinc = tsize; 455 if (toff + tinc > PAGE_SIZE) 456 tinc = PAGE_SIZE - toff; 457 if (vm_page_trysbusy(tbp->b_pages[j]) == 0) 458 break; 459 if ((tbp->b_pages[j]->valid & 460 vm_page_bits(toff, tinc)) != 0) { 461 vm_page_sunbusy(tbp->b_pages[j]); 462 break; 463 } 464 vm_object_pip_add(tbp->b_bufobj->bo_object, 1); 465 off += tinc; 466 tsize -= tinc; 467 } 468 if (tsize > 0) { 469 clean_sbusy: 470 vm_object_pip_wakeupn(tbp->b_bufobj->bo_object, 471 j); 472 for (k = 0; k < j; k++) 473 vm_page_sunbusy(tbp->b_pages[k]); 474 bqrelse(tbp); 475 break; 476 } 477 478 /* 479 * Set a read-ahead mark as appropriate 480 */ 481 if ((fbp && (i == 1)) || (i == (run - 1))) 482 tbp->b_flags |= B_RAM; 483 484 /* 485 * Set the buffer up for an async read (XXX should 486 * we do this only if we do not wind up brelse()ing?). 487 * Set the block number if it isn't set, otherwise 488 * if it is make sure it matches the block number we 489 * expect. 490 */ 491 tbp->b_flags |= B_ASYNC; 492 tbp->b_iocmd = BIO_READ; 493 if (tbp->b_blkno == tbp->b_lblkno) { 494 tbp->b_blkno = bn; 495 } else if (tbp->b_blkno != bn) { 496 goto clean_sbusy; 497 } 498 } 499 /* 500 * XXX fbp from caller may not be B_ASYNC, but we are going 501 * to biodone() it in cluster_callback() anyway 502 */ 503 BUF_KERNPROC(tbp); 504 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head, 505 tbp, b_cluster.cluster_entry); 506 for (j = 0; j < tbp->b_npages; j += 1) { 507 vm_page_t m; 508 509 m = tbp->b_pages[j]; 510 if ((bp->b_npages == 0) || 511 (bp->b_pages[bp->b_npages-1] != m)) { 512 bp->b_pages[bp->b_npages] = m; 513 bp->b_npages++; 514 } 515 if (vm_page_all_valid(m)) 516 tbp->b_pages[j] = bogus_page; 517 } 518 519 /* 520 * Don't inherit tbp->b_bufsize as it may be larger due to 521 * a non-page-aligned size. Instead just aggregate using 522 * 'size'. 523 */ 524 if (tbp->b_bcount != size) 525 printf("warning: tbp->b_bcount wrong %ld vs %ld\n", tbp->b_bcount, size); 526 if (tbp->b_bufsize != size) 527 printf("warning: tbp->b_bufsize wrong %ld vs %ld\n", tbp->b_bufsize, size); 528 bp->b_bcount += size; 529 bp->b_bufsize += size; 530 } 531 532 /* 533 * Fully valid pages in the cluster are already good and do not need 534 * to be re-read from disk. Replace the page with bogus_page 535 */ 536 for (j = 0; j < bp->b_npages; j++) { 537 if (vm_page_all_valid(bp->b_pages[j])) 538 bp->b_pages[j] = bogus_page; 539 } 540 if (bp->b_bufsize > bp->b_kvasize) 541 panic("cluster_rbuild: b_bufsize(%ld) > b_kvasize(%d)\n", 542 bp->b_bufsize, bp->b_kvasize); 543 544 if (buf_mapped(bp)) { 545 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 546 (vm_page_t *)bp->b_pages, bp->b_npages); 547 } 548 return (bp); 549 } 550 551 /* 552 * Cleanup after a clustered read or write. 553 * This is complicated by the fact that any of the buffers might have 554 * extra memory (if there were no empty buffer headers at allocbuf time) 555 * that we will need to shift around. 556 */ 557 static void 558 cluster_callback(struct buf *bp) 559 { 560 struct buf *nbp, *tbp; 561 int error = 0; 562 563 /* 564 * Must propagate errors to all the components. 565 */ 566 if (bp->b_ioflags & BIO_ERROR) 567 error = bp->b_error; 568 569 if (buf_mapped(bp)) { 570 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), 571 bp->b_npages); 572 } 573 /* 574 * Move memory from the large cluster buffer into the component 575 * buffers and mark IO as done on these. 576 */ 577 for (tbp = TAILQ_FIRST(&bp->b_cluster.cluster_head); 578 tbp; tbp = nbp) { 579 nbp = TAILQ_NEXT(&tbp->b_cluster, cluster_entry); 580 if (error) { 581 tbp->b_ioflags |= BIO_ERROR; 582 tbp->b_error = error; 583 } else { 584 tbp->b_dirtyoff = tbp->b_dirtyend = 0; 585 tbp->b_flags &= ~B_INVAL; 586 tbp->b_ioflags &= ~BIO_ERROR; 587 /* 588 * XXX the bdwrite()/bqrelse() issued during 589 * cluster building clears B_RELBUF (see bqrelse() 590 * comment). If direct I/O was specified, we have 591 * to restore it here to allow the buffer and VM 592 * to be freed. 593 */ 594 if (tbp->b_flags & B_DIRECT) 595 tbp->b_flags |= B_RELBUF; 596 } 597 bufdone(tbp); 598 } 599 pbrelvp(bp); 600 uma_zfree(cluster_pbuf_zone, bp); 601 } 602 603 /* 604 * cluster_wbuild_wb: 605 * 606 * Implement modified write build for cluster. 607 * 608 * write_behind = 0 write behind disabled 609 * write_behind = 1 write behind normal (default) 610 * write_behind = 2 write behind backed-off 611 */ 612 613 static __inline int 614 cluster_wbuild_wb(struct vnode *vp, long size, daddr_t start_lbn, int len, 615 int gbflags) 616 { 617 int r = 0; 618 619 switch (write_behind) { 620 case 2: 621 if (start_lbn < len) 622 break; 623 start_lbn -= len; 624 /* FALLTHROUGH */ 625 case 1: 626 r = cluster_wbuild(vp, size, start_lbn, len, gbflags); 627 /* FALLTHROUGH */ 628 default: 629 /* FALLTHROUGH */ 630 break; 631 } 632 return(r); 633 } 634 635 /* 636 * Do clustered write for FFS. 637 * 638 * Three cases: 639 * 1. Write is not sequential (write asynchronously) 640 * Write is sequential: 641 * 2. beginning of cluster - begin cluster 642 * 3. middle of a cluster - add to cluster 643 * 4. end of a cluster - asynchronously write cluster 644 */ 645 void 646 cluster_write(struct vnode *vp, struct buf *bp, u_quad_t filesize, int seqcount, 647 int gbflags) 648 { 649 daddr_t lbn, pbn; 650 int maxclen, cursize; 651 int lblocksize; 652 int async; 653 654 if (!unmapped_buf_allowed) 655 gbflags &= ~GB_UNMAPPED; 656 657 if (vp->v_type == VREG) { 658 async = DOINGASYNC(vp); 659 lblocksize = vp->v_mount->mnt_stat.f_iosize; 660 } else { 661 async = 0; 662 lblocksize = bp->b_bufsize; 663 } 664 lbn = bp->b_lblkno; 665 KASSERT(bp->b_offset != NOOFFSET, ("cluster_write: no buffer offset")); 666 667 /* Initialize vnode to beginning of file. */ 668 if (lbn == 0) 669 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0; 670 671 if (vp->v_clen == 0 || lbn != vp->v_lastw + 1 || 672 (bp->b_blkno != vp->v_lasta + btodb(lblocksize))) { 673 maxclen = vp->v_mount->mnt_iosize_max / lblocksize - 1; 674 if (vp->v_clen != 0) { 675 /* 676 * Next block is not sequential. 677 * 678 * If we are not writing at end of file, the process 679 * seeked to another point in the file since its last 680 * write, or we have reached our maximum cluster size, 681 * then push the previous cluster. Otherwise try 682 * reallocating to make it sequential. 683 * 684 * Change to algorithm: only push previous cluster if 685 * it was sequential from the point of view of the 686 * seqcount heuristic, otherwise leave the buffer 687 * intact so we can potentially optimize the I/O 688 * later on in the buf_daemon or update daemon 689 * flush. 690 */ 691 cursize = vp->v_lastw - vp->v_cstart + 1; 692 if (((u_quad_t) bp->b_offset + lblocksize) != filesize || 693 lbn != vp->v_lastw + 1 || vp->v_clen <= cursize) { 694 if (!async && seqcount > 0) { 695 cluster_wbuild_wb(vp, lblocksize, 696 vp->v_cstart, cursize, gbflags); 697 } 698 } else { 699 struct buf **bpp, **endbp; 700 struct cluster_save *buflist; 701 702 buflist = cluster_collectbufs(vp, bp, gbflags); 703 if (buflist == NULL) { 704 /* 705 * Cluster build failed so just write 706 * it now. 707 */ 708 bawrite(bp); 709 return; 710 } 711 endbp = &buflist->bs_children 712 [buflist->bs_nchildren - 1]; 713 if (VOP_REALLOCBLKS(vp, buflist)) { 714 /* 715 * Failed, push the previous cluster 716 * if *really* writing sequentially 717 * in the logical file (seqcount > 1), 718 * otherwise delay it in the hopes that 719 * the low level disk driver can 720 * optimize the write ordering. 721 */ 722 for (bpp = buflist->bs_children; 723 bpp < endbp; bpp++) 724 brelse(*bpp); 725 free(buflist, M_SEGMENT); 726 if (seqcount > 1) { 727 cluster_wbuild_wb(vp, 728 lblocksize, vp->v_cstart, 729 cursize, gbflags); 730 } 731 } else { 732 /* 733 * Succeeded, keep building cluster. 734 */ 735 for (bpp = buflist->bs_children; 736 bpp <= endbp; bpp++) 737 bdwrite(*bpp); 738 free(buflist, M_SEGMENT); 739 vp->v_lastw = lbn; 740 vp->v_lasta = bp->b_blkno; 741 return; 742 } 743 } 744 } 745 /* 746 * Consider beginning a cluster. If at end of file, make 747 * cluster as large as possible, otherwise find size of 748 * existing cluster. 749 */ 750 if ((vp->v_type == VREG) && 751 ((u_quad_t) bp->b_offset + lblocksize) != filesize && 752 (bp->b_blkno == bp->b_lblkno) && 753 (VOP_BMAP(vp, lbn, NULL, &bp->b_blkno, &maxclen, NULL) || 754 bp->b_blkno == -1)) { 755 pbn = bp->b_blkno; 756 bawrite(bp); 757 vp->v_clen = 0; 758 vp->v_lasta = pbn; 759 vp->v_cstart = lbn + 1; 760 vp->v_lastw = lbn; 761 return; 762 } 763 vp->v_clen = maxclen; 764 pbn = bp->b_blkno; 765 if (!async && maxclen == 0) { /* I/O not contiguous */ 766 vp->v_cstart = lbn + 1; 767 bawrite(bp); 768 } else { /* Wait for rest of cluster */ 769 vp->v_cstart = lbn; 770 bdwrite(bp); 771 } 772 } else if (lbn == vp->v_cstart + vp->v_clen) { 773 /* 774 * At end of cluster, write it out if seqcount tells us we 775 * are operating sequentially, otherwise let the buf or 776 * update daemon handle it. 777 */ 778 pbn = bp->b_blkno; 779 bdwrite(bp); 780 if (seqcount > 1) { 781 cluster_wbuild_wb(vp, lblocksize, vp->v_cstart, 782 vp->v_clen + 1, gbflags); 783 } 784 vp->v_clen = 0; 785 vp->v_cstart = lbn + 1; 786 } else if (vm_page_count_severe()) { 787 /* 788 * We are low on memory, get it going NOW 789 */ 790 pbn = bp->b_blkno; 791 bawrite(bp); 792 } else { 793 /* 794 * In the middle of a cluster, so just delay the I/O for now. 795 */ 796 pbn = bp->b_blkno; 797 bdwrite(bp); 798 } 799 vp->v_lastw = lbn; 800 vp->v_lasta = pbn; 801 } 802 803 /* 804 * This is an awful lot like cluster_rbuild...wish they could be combined. 805 * The last lbn argument is the current block on which I/O is being 806 * performed. Check to see that it doesn't fall in the middle of 807 * the current block (if last_bp == NULL). 808 */ 809 int 810 cluster_wbuild(struct vnode *vp, long size, daddr_t start_lbn, int len, 811 int gbflags) 812 { 813 struct buf *bp, *tbp; 814 struct bufobj *bo; 815 int i, j; 816 int totalwritten = 0; 817 int dbsize = btodb(size); 818 819 if (!unmapped_buf_allowed) 820 gbflags &= ~GB_UNMAPPED; 821 822 bo = &vp->v_bufobj; 823 while (len > 0) { 824 /* 825 * If the buffer is not delayed-write (i.e. dirty), or it 826 * is delayed-write but either locked or inval, it cannot 827 * partake in the clustered write. 828 */ 829 BO_LOCK(bo); 830 if ((tbp = gbincore(&vp->v_bufobj, start_lbn)) == NULL || 831 (tbp->b_vflags & BV_BKGRDINPROG)) { 832 BO_UNLOCK(bo); 833 ++start_lbn; 834 --len; 835 continue; 836 } 837 if (BUF_LOCK(tbp, 838 LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, BO_LOCKPTR(bo))) { 839 ++start_lbn; 840 --len; 841 continue; 842 } 843 if ((tbp->b_flags & (B_INVAL | B_DELWRI)) != B_DELWRI) { 844 BUF_UNLOCK(tbp); 845 ++start_lbn; 846 --len; 847 continue; 848 } 849 bremfree(tbp); 850 tbp->b_flags &= ~B_DONE; 851 852 /* 853 * Extra memory in the buffer, punt on this buffer. 854 * XXX we could handle this in most cases, but we would 855 * have to push the extra memory down to after our max 856 * possible cluster size and then potentially pull it back 857 * up if the cluster was terminated prematurely--too much 858 * hassle. 859 */ 860 if (((tbp->b_flags & (B_CLUSTEROK | B_MALLOC | B_VMIO)) != 861 (B_CLUSTEROK | B_VMIO)) || 862 (tbp->b_bcount != tbp->b_bufsize) || 863 (tbp->b_bcount != size) || 864 (len == 1) || 865 ((bp = uma_zalloc(cluster_pbuf_zone, M_NOWAIT)) == NULL)) { 866 totalwritten += tbp->b_bufsize; 867 bawrite(tbp); 868 ++start_lbn; 869 --len; 870 continue; 871 } 872 MPASS((bp->b_flags & B_MAXPHYS) != 0); 873 874 /* 875 * We got a pbuf to make the cluster in. 876 * so initialise it. 877 */ 878 TAILQ_INIT(&bp->b_cluster.cluster_head); 879 bp->b_bcount = 0; 880 bp->b_bufsize = 0; 881 bp->b_npages = 0; 882 if (tbp->b_wcred != NOCRED) 883 bp->b_wcred = crhold(tbp->b_wcred); 884 885 bp->b_blkno = tbp->b_blkno; 886 bp->b_lblkno = tbp->b_lblkno; 887 bp->b_offset = tbp->b_offset; 888 889 /* 890 * We are synthesizing a buffer out of vm_page_t's, but 891 * if the block size is not page aligned then the starting 892 * address may not be either. Inherit the b_data offset 893 * from the original buffer. 894 */ 895 if ((gbflags & GB_UNMAPPED) == 0 || 896 (tbp->b_flags & B_VMIO) == 0) { 897 bp->b_data = (char *)((vm_offset_t)bp->b_data | 898 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 899 } else { 900 bp->b_data = unmapped_buf; 901 } 902 bp->b_flags |= B_CLUSTER | (tbp->b_flags & (B_VMIO | 903 B_NEEDCOMMIT)); 904 bp->b_iodone = cluster_callback; 905 pbgetvp(vp, bp); 906 /* 907 * From this location in the file, scan forward to see 908 * if there are buffers with adjacent data that need to 909 * be written as well. 910 */ 911 for (i = 0; i < len; ++i, ++start_lbn) { 912 if (i != 0) { /* If not the first buffer */ 913 /* 914 * If the adjacent data is not even in core it 915 * can't need to be written. 916 */ 917 BO_LOCK(bo); 918 if ((tbp = gbincore(bo, start_lbn)) == NULL || 919 (tbp->b_vflags & BV_BKGRDINPROG)) { 920 BO_UNLOCK(bo); 921 break; 922 } 923 924 /* 925 * If it IS in core, but has different 926 * characteristics, or is locked (which 927 * means it could be undergoing a background 928 * I/O or be in a weird state), then don't 929 * cluster with it. 930 */ 931 if (BUF_LOCK(tbp, 932 LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, 933 BO_LOCKPTR(bo))) 934 break; 935 936 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK | 937 B_INVAL | B_DELWRI | B_NEEDCOMMIT)) 938 != (B_DELWRI | B_CLUSTEROK | 939 (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) || 940 tbp->b_wcred != bp->b_wcred) { 941 BUF_UNLOCK(tbp); 942 break; 943 } 944 945 /* 946 * Check that the combined cluster 947 * would make sense with regard to pages 948 * and would not be too large 949 */ 950 if ((tbp->b_bcount != size) || 951 ((bp->b_blkno + (dbsize * i)) != 952 tbp->b_blkno) || 953 ((tbp->b_npages + bp->b_npages) > 954 (vp->v_mount->mnt_iosize_max / PAGE_SIZE))) { 955 BUF_UNLOCK(tbp); 956 break; 957 } 958 959 /* 960 * Ok, it's passed all the tests, 961 * so remove it from the free list 962 * and mark it busy. We will use it. 963 */ 964 bremfree(tbp); 965 tbp->b_flags &= ~B_DONE; 966 } /* end of code for non-first buffers only */ 967 /* 968 * If the IO is via the VM then we do some 969 * special VM hackery (yuck). Since the buffer's 970 * block size may not be page-aligned it is possible 971 * for a page to be shared between two buffers. We 972 * have to get rid of the duplication when building 973 * the cluster. 974 */ 975 if (tbp->b_flags & B_VMIO) { 976 vm_page_t m; 977 978 if (i == 0) { 979 vfs_busy_pages_acquire(tbp); 980 } else { /* if not first buffer */ 981 for (j = 0; j < tbp->b_npages; j += 1) { 982 m = tbp->b_pages[j]; 983 if (vm_page_trysbusy(m) == 0) { 984 for (j--; j >= 0; j--) 985 vm_page_sunbusy( 986 tbp->b_pages[j]); 987 bqrelse(tbp); 988 goto finishcluster; 989 } 990 } 991 } 992 vm_object_pip_add(tbp->b_bufobj->bo_object, 993 tbp->b_npages); 994 for (j = 0; j < tbp->b_npages; j += 1) { 995 m = tbp->b_pages[j]; 996 if ((bp->b_npages == 0) || 997 (bp->b_pages[bp->b_npages - 1] != m)) { 998 bp->b_pages[bp->b_npages] = m; 999 bp->b_npages++; 1000 } 1001 } 1002 } 1003 bp->b_bcount += size; 1004 bp->b_bufsize += size; 1005 /* 1006 * If any of the clustered buffers have their 1007 * B_BARRIER flag set, transfer that request to 1008 * the cluster. 1009 */ 1010 bp->b_flags |= (tbp->b_flags & B_BARRIER); 1011 tbp->b_flags &= ~(B_DONE | B_BARRIER); 1012 tbp->b_flags |= B_ASYNC; 1013 tbp->b_ioflags &= ~BIO_ERROR; 1014 tbp->b_iocmd = BIO_WRITE; 1015 bundirty(tbp); 1016 reassignbuf(tbp); /* put on clean list */ 1017 bufobj_wref(tbp->b_bufobj); 1018 BUF_KERNPROC(tbp); 1019 buf_track(tbp, __func__); 1020 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head, 1021 tbp, b_cluster.cluster_entry); 1022 } 1023 finishcluster: 1024 if (buf_mapped(bp)) { 1025 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 1026 (vm_page_t *)bp->b_pages, bp->b_npages); 1027 } 1028 if (bp->b_bufsize > bp->b_kvasize) 1029 panic( 1030 "cluster_wbuild: b_bufsize(%ld) > b_kvasize(%d)\n", 1031 bp->b_bufsize, bp->b_kvasize); 1032 totalwritten += bp->b_bufsize; 1033 bp->b_dirtyoff = 0; 1034 bp->b_dirtyend = bp->b_bufsize; 1035 bawrite(bp); 1036 1037 len -= i; 1038 } 1039 return totalwritten; 1040 } 1041 1042 /* 1043 * Collect together all the buffers in a cluster. 1044 * Plus add one additional buffer. 1045 */ 1046 static struct cluster_save * 1047 cluster_collectbufs(struct vnode *vp, struct buf *last_bp, int gbflags) 1048 { 1049 struct cluster_save *buflist; 1050 struct buf *bp; 1051 daddr_t lbn; 1052 int i, j, len, error; 1053 1054 len = vp->v_lastw - vp->v_cstart + 1; 1055 buflist = malloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist), 1056 M_SEGMENT, M_WAITOK); 1057 buflist->bs_nchildren = 0; 1058 buflist->bs_children = (struct buf **) (buflist + 1); 1059 for (lbn = vp->v_cstart, i = 0; i < len; lbn++, i++) { 1060 error = bread_gb(vp, lbn, last_bp->b_bcount, NOCRED, 1061 gbflags, &bp); 1062 if (error != 0) { 1063 /* 1064 * If read fails, release collected buffers 1065 * and return failure. 1066 */ 1067 for (j = 0; j < i; j++) 1068 brelse(buflist->bs_children[j]); 1069 free(buflist, M_SEGMENT); 1070 return (NULL); 1071 } 1072 buflist->bs_children[i] = bp; 1073 if (bp->b_blkno == bp->b_lblkno) 1074 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, 1075 NULL, NULL); 1076 } 1077 buflist->bs_children[i] = bp = last_bp; 1078 if (bp->b_blkno == bp->b_lblkno) 1079 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 1080 buflist->bs_nchildren = i + 1; 1081 return (buflist); 1082 }
Cache object: 4fc263427a9b2e41c0bfd1ab5367e223
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