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