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