1 /*- 2 * Copyright (c) 1993 3 * The Regents of the University of California. All rights reserved. 4 * Modifications/enhancements: 5 * Copyright (c) 1995 John S. Dyson. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 * 31 * @(#)vfs_cluster.c 8.7 (Berkeley) 2/13/94 32 */ 33 34 #include <sys/cdefs.h> 35 __FBSDID("$FreeBSD$"); 36 37 #include "opt_debug_cluster.h" 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 #if defined(CLUSTERDEBUG) 58 static int rcluster= 0; 59 SYSCTL_INT(_debug, OID_AUTO, rcluster, CTLFLAG_RW, &rcluster, 0, 60 "Debug VFS clustering code"); 61 #endif 62 63 static MALLOC_DEFINE(M_SEGMENT, "cl_savebuf", "cluster_save buffer"); 64 65 static struct cluster_save *cluster_collectbufs(struct vnode *vp, 66 struct buf *last_bp, int gbflags); 67 static struct buf *cluster_rbuild(struct vnode *vp, u_quad_t filesize, 68 daddr_t lbn, daddr_t blkno, long size, int run, int gbflags, 69 struct buf *fbp); 70 static void cluster_callback(struct buf *); 71 72 static int write_behind = 1; 73 SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0, 74 "Cluster write-behind; 0: disable, 1: enable, 2: backed off"); 75 76 static int read_max = 64; 77 SYSCTL_INT(_vfs, OID_AUTO, read_max, CTLFLAG_RW, &read_max, 0, 78 "Cluster read-ahead max block count"); 79 80 static int read_min = 1; 81 SYSCTL_INT(_vfs, OID_AUTO, read_min, CTLFLAG_RW, &read_min, 0, 82 "Cluster read min block count"); 83 84 /* 85 * Read data to a buf, including read-ahead if we find this to be beneficial. 86 * cluster_read replaces bread. 87 */ 88 int 89 cluster_read(struct vnode *vp, u_quad_t filesize, daddr_t lblkno, long size, 90 struct ucred *cred, long totread, int seqcount, int gbflags, 91 struct buf **bpp) 92 { 93 struct buf *bp, *rbp, *reqbp; 94 struct bufobj *bo; 95 daddr_t blkno, origblkno; 96 int maxra, racluster; 97 int error, ncontig; 98 int i; 99 100 error = 0; 101 bo = &vp->v_bufobj; 102 if (!unmapped_buf_allowed) 103 gbflags &= ~GB_UNMAPPED; 104 105 /* 106 * Try to limit the amount of read-ahead by a few 107 * ad-hoc parameters. This needs work!!! 108 */ 109 racluster = vp->v_mount->mnt_iosize_max / size; 110 maxra = seqcount; 111 maxra = min(read_max, maxra); 112 maxra = min(nbuf/8, maxra); 113 if (((u_quad_t)(lblkno + maxra + 1) * size) > filesize) 114 maxra = (filesize / size) - lblkno; 115 116 /* 117 * get the requested block 118 */ 119 *bpp = reqbp = bp = getblk(vp, lblkno, size, 0, 0, gbflags); 120 if (bp == NULL) 121 return (EBUSY); 122 origblkno = lblkno; 123 124 /* 125 * if it is in the cache, then check to see if the reads have been 126 * sequential. If they have, then try some read-ahead, otherwise 127 * back-off on prospective read-aheads. 128 */ 129 if (bp->b_flags & B_CACHE) { 130 if (!seqcount) { 131 return 0; 132 } else if ((bp->b_flags & B_RAM) == 0) { 133 return 0; 134 } else { 135 bp->b_flags &= ~B_RAM; 136 BO_RLOCK(bo); 137 for (i = 1; i < maxra; i++) { 138 /* 139 * Stop if the buffer does not exist or it 140 * is invalid (about to go away?) 141 */ 142 rbp = gbincore(&vp->v_bufobj, lblkno+i); 143 if (rbp == NULL || (rbp->b_flags & B_INVAL)) 144 break; 145 146 /* 147 * Set another read-ahead mark so we know 148 * to check again. (If we can lock the 149 * buffer without waiting) 150 */ 151 if ((((i % racluster) == (racluster - 1)) || 152 (i == (maxra - 1))) 153 && (0 == BUF_LOCK(rbp, 154 LK_EXCLUSIVE | LK_NOWAIT, NULL))) { 155 rbp->b_flags |= B_RAM; 156 BUF_UNLOCK(rbp); 157 } 158 } 159 BO_RUNLOCK(bo); 160 if (i >= maxra) { 161 return 0; 162 } 163 lblkno += i; 164 } 165 reqbp = bp = NULL; 166 /* 167 * If it isn't in the cache, then get a chunk from 168 * disk if sequential, otherwise just get the block. 169 */ 170 } else { 171 off_t firstread = bp->b_offset; 172 int nblks; 173 long minread; 174 175 KASSERT(bp->b_offset != NOOFFSET, 176 ("cluster_read: no buffer offset")); 177 178 ncontig = 0; 179 180 /* 181 * Adjust totread if needed 182 */ 183 minread = read_min * size; 184 if (minread > totread) 185 totread = minread; 186 187 /* 188 * Compute the total number of blocks that we should read 189 * synchronously. 190 */ 191 if (firstread + totread > filesize) 192 totread = filesize - firstread; 193 nblks = howmany(totread, size); 194 if (nblks > racluster) 195 nblks = racluster; 196 197 /* 198 * Now compute the number of contiguous blocks. 199 */ 200 if (nblks > 1) { 201 error = VOP_BMAP(vp, lblkno, NULL, 202 &blkno, &ncontig, NULL); 203 /* 204 * If this failed to map just do the original block. 205 */ 206 if (error || blkno == -1) 207 ncontig = 0; 208 } 209 210 /* 211 * If we have contiguous data available do a cluster 212 * otherwise just read the requested block. 213 */ 214 if (ncontig) { 215 /* Account for our first block. */ 216 ncontig = min(ncontig + 1, nblks); 217 if (ncontig < nblks) 218 nblks = ncontig; 219 bp = cluster_rbuild(vp, filesize, lblkno, 220 blkno, size, nblks, gbflags, bp); 221 lblkno += (bp->b_bufsize / size); 222 } else { 223 bp->b_flags |= B_RAM; 224 bp->b_iocmd = BIO_READ; 225 lblkno += 1; 226 } 227 } 228 229 /* 230 * handle the synchronous read so that it is available ASAP. 231 */ 232 if (bp) { 233 if ((bp->b_flags & B_CLUSTER) == 0) { 234 vfs_busy_pages(bp, 0); 235 } 236 bp->b_flags &= ~B_INVAL; 237 bp->b_ioflags &= ~BIO_ERROR; 238 if ((bp->b_flags & B_ASYNC) || bp->b_iodone != NULL) 239 BUF_KERNPROC(bp); 240 bp->b_iooffset = dbtob(bp->b_blkno); 241 bstrategy(bp); 242 #ifdef RACCT 243 if (racct_enable) { 244 PROC_LOCK(curproc); 245 racct_add_buf(curproc, bp, 0); 246 PROC_UNLOCK(curproc); 247 } 248 #endif /* RACCT */ 249 curthread->td_ru.ru_inblock++; 250 } 251 252 /* 253 * If we have been doing sequential I/O, then do some read-ahead. 254 */ 255 while (lblkno < (origblkno + maxra)) { 256 error = VOP_BMAP(vp, lblkno, NULL, &blkno, &ncontig, NULL); 257 if (error) 258 break; 259 260 if (blkno == -1) 261 break; 262 263 /* 264 * We could throttle ncontig here by maxra but we might as 265 * well read the data if it is contiguous. We're throttled 266 * by racluster anyway. 267 */ 268 if (ncontig) { 269 ncontig = min(ncontig + 1, racluster); 270 rbp = cluster_rbuild(vp, filesize, lblkno, blkno, 271 size, ncontig, gbflags, NULL); 272 lblkno += (rbp->b_bufsize / size); 273 if (rbp->b_flags & B_DELWRI) { 274 bqrelse(rbp); 275 continue; 276 } 277 } else { 278 rbp = getblk(vp, lblkno, size, 0, 0, gbflags); 279 lblkno += 1; 280 if (rbp->b_flags & B_DELWRI) { 281 bqrelse(rbp); 282 continue; 283 } 284 rbp->b_flags |= B_ASYNC | B_RAM; 285 rbp->b_iocmd = BIO_READ; 286 rbp->b_blkno = blkno; 287 } 288 if (rbp->b_flags & B_CACHE) { 289 rbp->b_flags &= ~B_ASYNC; 290 bqrelse(rbp); 291 continue; 292 } 293 if ((rbp->b_flags & B_CLUSTER) == 0) { 294 vfs_busy_pages(rbp, 0); 295 } 296 rbp->b_flags &= ~B_INVAL; 297 rbp->b_ioflags &= ~BIO_ERROR; 298 if ((rbp->b_flags & B_ASYNC) || rbp->b_iodone != NULL) 299 BUF_KERNPROC(rbp); 300 rbp->b_iooffset = dbtob(rbp->b_blkno); 301 bstrategy(rbp); 302 #ifdef RACCT 303 if (racct_enable) { 304 PROC_LOCK(curproc); 305 racct_add_buf(curproc, rbp, 0); 306 PROC_UNLOCK(curproc); 307 } 308 #endif /* RACCT */ 309 curthread->td_ru.ru_inblock++; 310 } 311 312 if (reqbp) { 313 /* 314 * Like bread, always brelse() the buffer when 315 * returning an error. 316 */ 317 error = bufwait(reqbp); 318 if (error != 0) { 319 brelse(reqbp); 320 *bpp = NULL; 321 } 322 } 323 return (error); 324 } 325 326 /* 327 * If blocks are contiguous on disk, use this to provide clustered 328 * read ahead. We will read as many blocks as possible sequentially 329 * and then parcel them up into logical blocks in the buffer hash table. 330 */ 331 static struct buf * 332 cluster_rbuild(struct vnode *vp, u_quad_t filesize, daddr_t lbn, 333 daddr_t blkno, long size, int run, int gbflags, struct buf *fbp) 334 { 335 struct buf *bp, *tbp; 336 daddr_t bn; 337 off_t off; 338 long tinc, tsize; 339 int i, inc, j, k, toff; 340 341 KASSERT(size == vp->v_mount->mnt_stat.f_iosize, 342 ("cluster_rbuild: size %ld != f_iosize %jd\n", 343 size, (intmax_t)vp->v_mount->mnt_stat.f_iosize)); 344 345 /* 346 * avoid a division 347 */ 348 while ((u_quad_t) size * (lbn + run) > filesize) { 349 --run; 350 } 351 352 if (fbp) { 353 tbp = fbp; 354 tbp->b_iocmd = BIO_READ; 355 } else { 356 tbp = getblk(vp, lbn, size, 0, 0, gbflags); 357 if (tbp->b_flags & B_CACHE) 358 return tbp; 359 tbp->b_flags |= B_ASYNC | B_RAM; 360 tbp->b_iocmd = BIO_READ; 361 } 362 tbp->b_blkno = blkno; 363 if( (tbp->b_flags & B_MALLOC) || 364 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1) ) 365 return tbp; 366 367 bp = trypbuf(&cluster_pbuf_freecnt); 368 if (bp == NULL) 369 return tbp; 370 371 /* 372 * We are synthesizing a buffer out of vm_page_t's, but 373 * if the block size is not page aligned then the starting 374 * address may not be either. Inherit the b_data offset 375 * from the original buffer. 376 */ 377 bp->b_flags = B_ASYNC | B_CLUSTER | B_VMIO; 378 if ((gbflags & GB_UNMAPPED) != 0) { 379 bp->b_data = unmapped_buf; 380 } else { 381 bp->b_data = (char *)((vm_offset_t)bp->b_data | 382 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 383 } 384 bp->b_iocmd = BIO_READ; 385 bp->b_iodone = cluster_callback; 386 bp->b_blkno = blkno; 387 bp->b_lblkno = lbn; 388 bp->b_offset = tbp->b_offset; 389 KASSERT(bp->b_offset != NOOFFSET, ("cluster_rbuild: no buffer offset")); 390 pbgetvp(vp, bp); 391 392 TAILQ_INIT(&bp->b_cluster.cluster_head); 393 394 bp->b_bcount = 0; 395 bp->b_bufsize = 0; 396 bp->b_npages = 0; 397 398 inc = btodb(size); 399 for (bn = blkno, i = 0; i < run; ++i, bn += inc) { 400 if (i == 0) { 401 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object); 402 vfs_drain_busy_pages(tbp); 403 vm_object_pip_add(tbp->b_bufobj->bo_object, 404 tbp->b_npages); 405 for (k = 0; k < tbp->b_npages; k++) 406 vm_page_sbusy(tbp->b_pages[k]); 407 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object); 408 } else { 409 if ((bp->b_npages * PAGE_SIZE) + 410 round_page(size) > vp->v_mount->mnt_iosize_max) { 411 break; 412 } 413 414 tbp = getblk(vp, lbn + i, size, 0, 0, GB_LOCK_NOWAIT | 415 (gbflags & GB_UNMAPPED)); 416 417 /* Don't wait around for locked bufs. */ 418 if (tbp == NULL) 419 break; 420 421 /* 422 * Stop scanning if the buffer is fully valid 423 * (marked B_CACHE), or locked (may be doing a 424 * background write), or if the buffer is not 425 * VMIO backed. The clustering code can only deal 426 * with VMIO-backed buffers. The bo lock is not 427 * required for the BKGRDINPROG check since it 428 * can not be set without the buf lock. 429 */ 430 if ((tbp->b_vflags & BV_BKGRDINPROG) || 431 (tbp->b_flags & B_CACHE) || 432 (tbp->b_flags & B_VMIO) == 0) { 433 bqrelse(tbp); 434 break; 435 } 436 437 /* 438 * The buffer must be completely invalid in order to 439 * take part in the cluster. If it is partially valid 440 * then we stop. 441 */ 442 off = tbp->b_offset; 443 tsize = size; 444 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object); 445 for (j = 0; tsize > 0; j++) { 446 toff = off & PAGE_MASK; 447 tinc = tsize; 448 if (toff + tinc > PAGE_SIZE) 449 tinc = PAGE_SIZE - toff; 450 VM_OBJECT_ASSERT_WLOCKED(tbp->b_pages[j]->object); 451 if ((tbp->b_pages[j]->valid & 452 vm_page_bits(toff, tinc)) != 0) 453 break; 454 if (vm_page_xbusied(tbp->b_pages[j])) 455 break; 456 vm_object_pip_add(tbp->b_bufobj->bo_object, 1); 457 vm_page_sbusy(tbp->b_pages[j]); 458 off += tinc; 459 tsize -= tinc; 460 } 461 if (tsize > 0) { 462 clean_sbusy: 463 vm_object_pip_add(tbp->b_bufobj->bo_object, -j); 464 for (k = 0; k < j; k++) 465 vm_page_sunbusy(tbp->b_pages[k]); 466 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object); 467 bqrelse(tbp); 468 break; 469 } 470 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object); 471 472 /* 473 * Set a read-ahead mark as appropriate 474 */ 475 if ((fbp && (i == 1)) || (i == (run - 1))) 476 tbp->b_flags |= B_RAM; 477 478 /* 479 * Set the buffer up for an async read (XXX should 480 * we do this only if we do not wind up brelse()ing?). 481 * Set the block number if it isn't set, otherwise 482 * if it is make sure it matches the block number we 483 * expect. 484 */ 485 tbp->b_flags |= B_ASYNC; 486 tbp->b_iocmd = BIO_READ; 487 if (tbp->b_blkno == tbp->b_lblkno) { 488 tbp->b_blkno = bn; 489 } else if (tbp->b_blkno != bn) { 490 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object); 491 goto clean_sbusy; 492 } 493 } 494 /* 495 * XXX fbp from caller may not be B_ASYNC, but we are going 496 * to biodone() it in cluster_callback() anyway 497 */ 498 BUF_KERNPROC(tbp); 499 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head, 500 tbp, b_cluster.cluster_entry); 501 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object); 502 for (j = 0; j < tbp->b_npages; j += 1) { 503 vm_page_t m; 504 m = tbp->b_pages[j]; 505 if ((bp->b_npages == 0) || 506 (bp->b_pages[bp->b_npages-1] != m)) { 507 bp->b_pages[bp->b_npages] = m; 508 bp->b_npages++; 509 } 510 if (m->valid == VM_PAGE_BITS_ALL) 511 tbp->b_pages[j] = bogus_page; 512 } 513 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object); 514 /* 515 * Don't inherit tbp->b_bufsize as it may be larger due to 516 * a non-page-aligned size. Instead just aggregate using 517 * 'size'. 518 */ 519 if (tbp->b_bcount != size) 520 printf("warning: tbp->b_bcount wrong %ld vs %ld\n", tbp->b_bcount, size); 521 if (tbp->b_bufsize != size) 522 printf("warning: tbp->b_bufsize wrong %ld vs %ld\n", tbp->b_bufsize, size); 523 bp->b_bcount += size; 524 bp->b_bufsize += size; 525 } 526 527 /* 528 * Fully valid pages in the cluster are already good and do not need 529 * to be re-read from disk. Replace the page with bogus_page 530 */ 531 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 532 for (j = 0; j < bp->b_npages; j++) { 533 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[j]->object); 534 if (bp->b_pages[j]->valid == VM_PAGE_BITS_ALL) 535 bp->b_pages[j] = bogus_page; 536 } 537 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 538 if (bp->b_bufsize > bp->b_kvasize) 539 panic("cluster_rbuild: b_bufsize(%ld) > b_kvasize(%d)\n", 540 bp->b_bufsize, bp->b_kvasize); 541 542 if (buf_mapped(bp)) { 543 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 544 (vm_page_t *)bp->b_pages, bp->b_npages); 545 } 546 return (bp); 547 } 548 549 /* 550 * Cleanup after a clustered read or write. 551 * This is complicated by the fact that any of the buffers might have 552 * extra memory (if there were no empty buffer headers at allocbuf time) 553 * that we will need to shift around. 554 */ 555 static void 556 cluster_callback(bp) 557 struct buf *bp; 558 { 559 struct buf *nbp, *tbp; 560 int error = 0; 561 562 /* 563 * Must propagate errors to all the components. 564 */ 565 if (bp->b_ioflags & BIO_ERROR) 566 error = bp->b_error; 567 568 if (buf_mapped(bp)) { 569 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), 570 bp->b_npages); 571 } 572 /* 573 * Move memory from the large cluster buffer into the component 574 * buffers and mark IO as done on these. 575 */ 576 for (tbp = TAILQ_FIRST(&bp->b_cluster.cluster_head); 577 tbp; tbp = nbp) { 578 nbp = TAILQ_NEXT(&tbp->b_cluster, cluster_entry); 579 if (error) { 580 tbp->b_ioflags |= BIO_ERROR; 581 tbp->b_error = error; 582 } else { 583 tbp->b_dirtyoff = tbp->b_dirtyend = 0; 584 tbp->b_flags &= ~B_INVAL; 585 tbp->b_ioflags &= ~BIO_ERROR; 586 /* 587 * XXX the bdwrite()/bqrelse() issued during 588 * cluster building clears B_RELBUF (see bqrelse() 589 * comment). If direct I/O was specified, we have 590 * to restore it here to allow the buffer and VM 591 * to be freed. 592 */ 593 if (tbp->b_flags & B_DIRECT) 594 tbp->b_flags |= B_RELBUF; 595 } 596 bufdone(tbp); 597 } 598 pbrelvp(bp); 599 relpbuf(bp, &cluster_pbuf_freecnt); 600 } 601 602 /* 603 * cluster_wbuild_wb: 604 * 605 * Implement modified write build for cluster. 606 * 607 * write_behind = 0 write behind disabled 608 * write_behind = 1 write behind normal (default) 609 * write_behind = 2 write behind backed-off 610 */ 611 612 static __inline int 613 cluster_wbuild_wb(struct vnode *vp, long size, daddr_t start_lbn, int len, 614 int gbflags) 615 { 616 int r = 0; 617 618 switch (write_behind) { 619 case 2: 620 if (start_lbn < len) 621 break; 622 start_lbn -= len; 623 /* FALLTHROUGH */ 624 case 1: 625 r = cluster_wbuild(vp, size, start_lbn, len, gbflags); 626 /* FALLTHROUGH */ 627 default: 628 /* FALLTHROUGH */ 629 break; 630 } 631 return(r); 632 } 633 634 /* 635 * Do clustered write for FFS. 636 * 637 * Three cases: 638 * 1. Write is not sequential (write asynchronously) 639 * Write is sequential: 640 * 2. beginning of cluster - begin cluster 641 * 3. middle of a cluster - add to cluster 642 * 4. end of a cluster - asynchronously write cluster 643 */ 644 void 645 cluster_write(struct vnode *vp, struct buf *bp, u_quad_t filesize, int seqcount, 646 int gbflags) 647 { 648 daddr_t lbn; 649 int maxclen, cursize; 650 int lblocksize; 651 int async; 652 653 if (!unmapped_buf_allowed) 654 gbflags &= ~GB_UNMAPPED; 655 656 if (vp->v_type == VREG) { 657 async = DOINGASYNC(vp); 658 lblocksize = vp->v_mount->mnt_stat.f_iosize; 659 } else { 660 async = 0; 661 lblocksize = bp->b_bufsize; 662 } 663 lbn = bp->b_lblkno; 664 KASSERT(bp->b_offset != NOOFFSET, ("cluster_write: no buffer offset")); 665 666 /* Initialize vnode to beginning of file. */ 667 if (lbn == 0) 668 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0; 669 670 if (vp->v_clen == 0 || lbn != vp->v_lastw + 1 || 671 (bp->b_blkno != vp->v_lasta + btodb(lblocksize))) { 672 maxclen = vp->v_mount->mnt_iosize_max / lblocksize - 1; 673 if (vp->v_clen != 0) { 674 /* 675 * Next block is not sequential. 676 * 677 * If we are not writing at end of file, the process 678 * seeked to another point in the file since its last 679 * write, or we have reached our maximum cluster size, 680 * then push the previous cluster. Otherwise try 681 * reallocating to make it sequential. 682 * 683 * Change to algorithm: only push previous cluster if 684 * it was sequential from the point of view of the 685 * seqcount heuristic, otherwise leave the buffer 686 * intact so we can potentially optimize the I/O 687 * later on in the buf_daemon or update daemon 688 * flush. 689 */ 690 cursize = vp->v_lastw - vp->v_cstart + 1; 691 if (((u_quad_t) bp->b_offset + lblocksize) != filesize || 692 lbn != vp->v_lastw + 1 || vp->v_clen <= cursize) { 693 if (!async && seqcount > 0) { 694 cluster_wbuild_wb(vp, lblocksize, 695 vp->v_cstart, cursize, gbflags); 696 } 697 } else { 698 struct buf **bpp, **endbp; 699 struct cluster_save *buflist; 700 701 buflist = cluster_collectbufs(vp, bp, gbflags); 702 endbp = &buflist->bs_children 703 [buflist->bs_nchildren - 1]; 704 if (VOP_REALLOCBLKS(vp, buflist)) { 705 /* 706 * Failed, push the previous cluster 707 * if *really* writing sequentially 708 * in the logical file (seqcount > 1), 709 * otherwise delay it in the hopes that 710 * the low level disk driver can 711 * optimize the write ordering. 712 */ 713 for (bpp = buflist->bs_children; 714 bpp < endbp; bpp++) 715 brelse(*bpp); 716 free(buflist, M_SEGMENT); 717 if (seqcount > 1) { 718 cluster_wbuild_wb(vp, 719 lblocksize, vp->v_cstart, 720 cursize, gbflags); 721 } 722 } else { 723 /* 724 * Succeeded, keep building cluster. 725 */ 726 for (bpp = buflist->bs_children; 727 bpp <= endbp; bpp++) 728 bdwrite(*bpp); 729 free(buflist, M_SEGMENT); 730 vp->v_lastw = lbn; 731 vp->v_lasta = bp->b_blkno; 732 return; 733 } 734 } 735 } 736 /* 737 * Consider beginning a cluster. If at end of file, make 738 * cluster as large as possible, otherwise find size of 739 * existing cluster. 740 */ 741 if ((vp->v_type == VREG) && 742 ((u_quad_t) bp->b_offset + lblocksize) != filesize && 743 (bp->b_blkno == bp->b_lblkno) && 744 (VOP_BMAP(vp, lbn, NULL, &bp->b_blkno, &maxclen, NULL) || 745 bp->b_blkno == -1)) { 746 bawrite(bp); 747 vp->v_clen = 0; 748 vp->v_lasta = bp->b_blkno; 749 vp->v_cstart = lbn + 1; 750 vp->v_lastw = lbn; 751 return; 752 } 753 vp->v_clen = maxclen; 754 if (!async && maxclen == 0) { /* I/O not contiguous */ 755 vp->v_cstart = lbn + 1; 756 bawrite(bp); 757 } else { /* Wait for rest of cluster */ 758 vp->v_cstart = lbn; 759 bdwrite(bp); 760 } 761 } else if (lbn == vp->v_cstart + vp->v_clen) { 762 /* 763 * At end of cluster, write it out if seqcount tells us we 764 * are operating sequentially, otherwise let the buf or 765 * update daemon handle it. 766 */ 767 bdwrite(bp); 768 if (seqcount > 1) { 769 cluster_wbuild_wb(vp, lblocksize, vp->v_cstart, 770 vp->v_clen + 1, gbflags); 771 } 772 vp->v_clen = 0; 773 vp->v_cstart = lbn + 1; 774 } else if (vm_page_count_severe()) { 775 /* 776 * We are low on memory, get it going NOW 777 */ 778 bawrite(bp); 779 } else { 780 /* 781 * In the middle of a cluster, so just delay the I/O for now. 782 */ 783 bdwrite(bp); 784 } 785 vp->v_lastw = lbn; 786 vp->v_lasta = bp->b_blkno; 787 } 788 789 790 /* 791 * This is an awful lot like cluster_rbuild...wish they could be combined. 792 * The last lbn argument is the current block on which I/O is being 793 * performed. Check to see that it doesn't fall in the middle of 794 * the current block (if last_bp == NULL). 795 */ 796 int 797 cluster_wbuild(struct vnode *vp, long size, daddr_t start_lbn, int len, 798 int gbflags) 799 { 800 struct buf *bp, *tbp; 801 struct bufobj *bo; 802 int i, j; 803 int totalwritten = 0; 804 int dbsize = btodb(size); 805 806 if (!unmapped_buf_allowed) 807 gbflags &= ~GB_UNMAPPED; 808 809 bo = &vp->v_bufobj; 810 while (len > 0) { 811 /* 812 * If the buffer is not delayed-write (i.e. dirty), or it 813 * is delayed-write but either locked or inval, it cannot 814 * partake in the clustered write. 815 */ 816 BO_LOCK(bo); 817 if ((tbp = gbincore(&vp->v_bufobj, start_lbn)) == NULL || 818 (tbp->b_vflags & BV_BKGRDINPROG)) { 819 BO_UNLOCK(bo); 820 ++start_lbn; 821 --len; 822 continue; 823 } 824 if (BUF_LOCK(tbp, 825 LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, BO_LOCKPTR(bo))) { 826 ++start_lbn; 827 --len; 828 continue; 829 } 830 if ((tbp->b_flags & (B_INVAL | B_DELWRI)) != B_DELWRI) { 831 BUF_UNLOCK(tbp); 832 ++start_lbn; 833 --len; 834 continue; 835 } 836 bremfree(tbp); 837 tbp->b_flags &= ~B_DONE; 838 839 /* 840 * Extra memory in the buffer, punt on this buffer. 841 * XXX we could handle this in most cases, but we would 842 * have to push the extra memory down to after our max 843 * possible cluster size and then potentially pull it back 844 * up if the cluster was terminated prematurely--too much 845 * hassle. 846 */ 847 if (((tbp->b_flags & (B_CLUSTEROK | B_MALLOC | B_VMIO)) != 848 (B_CLUSTEROK | B_VMIO)) || 849 (tbp->b_bcount != tbp->b_bufsize) || 850 (tbp->b_bcount != size) || 851 (len == 1) || 852 ((bp = (vp->v_vflag & VV_MD) != 0 ? 853 trypbuf(&cluster_pbuf_freecnt) : 854 getpbuf(&cluster_pbuf_freecnt)) == NULL)) { 855 totalwritten += tbp->b_bufsize; 856 bawrite(tbp); 857 ++start_lbn; 858 --len; 859 continue; 860 } 861 862 /* 863 * We got a pbuf to make the cluster in. 864 * so initialise it. 865 */ 866 TAILQ_INIT(&bp->b_cluster.cluster_head); 867 bp->b_bcount = 0; 868 bp->b_bufsize = 0; 869 bp->b_npages = 0; 870 if (tbp->b_wcred != NOCRED) 871 bp->b_wcred = crhold(tbp->b_wcred); 872 873 bp->b_blkno = tbp->b_blkno; 874 bp->b_lblkno = tbp->b_lblkno; 875 bp->b_offset = tbp->b_offset; 876 877 /* 878 * We are synthesizing a buffer out of vm_page_t's, but 879 * if the block size is not page aligned then the starting 880 * address may not be either. Inherit the b_data offset 881 * from the original buffer. 882 */ 883 if ((gbflags & GB_UNMAPPED) == 0 || 884 (tbp->b_flags & B_VMIO) == 0) { 885 bp->b_data = (char *)((vm_offset_t)bp->b_data | 886 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 887 } else { 888 bp->b_data = unmapped_buf; 889 } 890 bp->b_flags |= B_CLUSTER | (tbp->b_flags & (B_VMIO | 891 B_NEEDCOMMIT)); 892 bp->b_iodone = cluster_callback; 893 pbgetvp(vp, bp); 894 /* 895 * From this location in the file, scan forward to see 896 * if there are buffers with adjacent data that need to 897 * be written as well. 898 */ 899 for (i = 0; i < len; ++i, ++start_lbn) { 900 if (i != 0) { /* If not the first buffer */ 901 /* 902 * If the adjacent data is not even in core it 903 * can't need to be written. 904 */ 905 BO_LOCK(bo); 906 if ((tbp = gbincore(bo, start_lbn)) == NULL || 907 (tbp->b_vflags & BV_BKGRDINPROG)) { 908 BO_UNLOCK(bo); 909 break; 910 } 911 912 /* 913 * If it IS in core, but has different 914 * characteristics, or is locked (which 915 * means it could be undergoing a background 916 * I/O or be in a weird state), then don't 917 * cluster with it. 918 */ 919 if (BUF_LOCK(tbp, 920 LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, 921 BO_LOCKPTR(bo))) 922 break; 923 924 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK | 925 B_INVAL | B_DELWRI | B_NEEDCOMMIT)) 926 != (B_DELWRI | B_CLUSTEROK | 927 (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) || 928 tbp->b_wcred != bp->b_wcred) { 929 BUF_UNLOCK(tbp); 930 break; 931 } 932 933 /* 934 * Check that the combined cluster 935 * would make sense with regard to pages 936 * and would not be too large 937 */ 938 if ((tbp->b_bcount != size) || 939 ((bp->b_blkno + (dbsize * i)) != 940 tbp->b_blkno) || 941 ((tbp->b_npages + bp->b_npages) > 942 (vp->v_mount->mnt_iosize_max / PAGE_SIZE))) { 943 BUF_UNLOCK(tbp); 944 break; 945 } 946 947 /* 948 * Ok, it's passed all the tests, 949 * so remove it from the free list 950 * and mark it busy. We will use it. 951 */ 952 bremfree(tbp); 953 tbp->b_flags &= ~B_DONE; 954 } /* end of code for non-first buffers only */ 955 /* 956 * If the IO is via the VM then we do some 957 * special VM hackery (yuck). Since the buffer's 958 * block size may not be page-aligned it is possible 959 * for a page to be shared between two buffers. We 960 * have to get rid of the duplication when building 961 * the cluster. 962 */ 963 if (tbp->b_flags & B_VMIO) { 964 vm_page_t m; 965 966 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object); 967 if (i == 0) { 968 vfs_drain_busy_pages(tbp); 969 } else { /* if not first buffer */ 970 for (j = 0; j < tbp->b_npages; j += 1) { 971 m = tbp->b_pages[j]; 972 if (vm_page_xbusied(m)) { 973 VM_OBJECT_WUNLOCK( 974 tbp->b_object); 975 bqrelse(tbp); 976 goto finishcluster; 977 } 978 } 979 } 980 for (j = 0; j < tbp->b_npages; j += 1) { 981 m = tbp->b_pages[j]; 982 vm_page_sbusy(m); 983 vm_object_pip_add(m->object, 1); 984 if ((bp->b_npages == 0) || 985 (bp->b_pages[bp->b_npages - 1] != m)) { 986 bp->b_pages[bp->b_npages] = m; 987 bp->b_npages++; 988 } 989 } 990 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object); 991 } 992 bp->b_bcount += size; 993 bp->b_bufsize += size; 994 /* 995 * If any of the clustered buffers have their 996 * B_BARRIER flag set, transfer that request to 997 * the cluster. 998 */ 999 bp->b_flags |= (tbp->b_flags & B_BARRIER); 1000 tbp->b_flags &= ~(B_DONE | B_BARRIER); 1001 tbp->b_flags |= B_ASYNC; 1002 tbp->b_ioflags &= ~BIO_ERROR; 1003 tbp->b_iocmd = BIO_WRITE; 1004 bundirty(tbp); 1005 reassignbuf(tbp); /* put on clean list */ 1006 bufobj_wref(tbp->b_bufobj); 1007 BUF_KERNPROC(tbp); 1008 buf_track(tbp, __func__); 1009 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head, 1010 tbp, b_cluster.cluster_entry); 1011 } 1012 finishcluster: 1013 if (buf_mapped(bp)) { 1014 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 1015 (vm_page_t *)bp->b_pages, bp->b_npages); 1016 } 1017 if (bp->b_bufsize > bp->b_kvasize) 1018 panic( 1019 "cluster_wbuild: b_bufsize(%ld) > b_kvasize(%d)\n", 1020 bp->b_bufsize, bp->b_kvasize); 1021 totalwritten += bp->b_bufsize; 1022 bp->b_dirtyoff = 0; 1023 bp->b_dirtyend = bp->b_bufsize; 1024 bawrite(bp); 1025 1026 len -= i; 1027 } 1028 return totalwritten; 1029 } 1030 1031 /* 1032 * Collect together all the buffers in a cluster. 1033 * Plus add one additional buffer. 1034 */ 1035 static struct cluster_save * 1036 cluster_collectbufs(struct vnode *vp, struct buf *last_bp, int gbflags) 1037 { 1038 struct cluster_save *buflist; 1039 struct buf *bp; 1040 daddr_t lbn; 1041 int i, len; 1042 1043 len = vp->v_lastw - vp->v_cstart + 1; 1044 buflist = malloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist), 1045 M_SEGMENT, M_WAITOK); 1046 buflist->bs_nchildren = 0; 1047 buflist->bs_children = (struct buf **) (buflist + 1); 1048 for (lbn = vp->v_cstart, i = 0; i < len; lbn++, i++) { 1049 (void)bread_gb(vp, lbn, last_bp->b_bcount, NOCRED, 1050 gbflags, &bp); 1051 buflist->bs_children[i] = bp; 1052 if (bp->b_blkno == bp->b_lblkno) 1053 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, 1054 NULL, NULL); 1055 } 1056 buflist->bs_children[i] = bp = last_bp; 1057 if (bp->b_blkno == bp->b_lblkno) 1058 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 1059 buflist->bs_nchildren = i + 1; 1060 return (buflist); 1061 } 1062