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