Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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sys/kern/vfs_cluster.c
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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 * 4. 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: releng/10.0/sys/kern/vfs_cluster.c 254945 2013-08-27 01:31:12Z kib $"); 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/resourcevar.h> 49 #include <sys/rwlock.h> 50 #include <sys/vmmeter.h> 51 #include <vm/vm.h> 52 #include <vm/vm_object.h> 53 #include <vm/vm_page.h> 54 #include <sys/sysctl.h> 55 56 #if defined(CLUSTERDEBUG) 57 static int rcluster= 0; 58 SYSCTL_INT(_debug, OID_AUTO, rcluster, CTLFLAG_RW, &rcluster, 0, 59 "Debug VFS clustering code"); 60 #endif 61 62 static MALLOC_DEFINE(M_SEGMENT, "cl_savebuf", "cluster_save buffer"); 63 64 static struct cluster_save *cluster_collectbufs(struct vnode *vp, 65 struct buf *last_bp, int gbflags); 66 static struct buf *cluster_rbuild(struct vnode *vp, u_quad_t filesize, 67 daddr_t lbn, daddr_t blkno, long size, int run, int gbflags, 68 struct buf *fbp); 69 static void cluster_callback(struct buf *); 70 71 static int write_behind = 1; 72 SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0, 73 "Cluster write-behind; 0: disable, 1: enable, 2: backed off"); 74 75 static int read_max = 64; 76 SYSCTL_INT(_vfs, OID_AUTO, read_max, CTLFLAG_RW, &read_max, 0, 77 "Cluster read-ahead max block count"); 78 79 static int read_min = 1; 80 SYSCTL_INT(_vfs, OID_AUTO, read_min, CTLFLAG_RW, &read_min, 0, 81 "Cluster read min block count"); 82 83 /* Page expended to mark partially backed buffers */ 84 extern vm_page_t bogus_page; 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 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 curthread->td_ru.ru_inblock++; 243 } 244 245 /* 246 * If we have been doing sequential I/O, then do some read-ahead. 247 */ 248 while (lblkno < (origblkno + maxra)) { 249 error = VOP_BMAP(vp, lblkno, NULL, &blkno, &ncontig, NULL); 250 if (error) 251 break; 252 253 if (blkno == -1) 254 break; 255 256 /* 257 * We could throttle ncontig here by maxra but we might as 258 * well read the data if it is contiguous. We're throttled 259 * by racluster anyway. 260 */ 261 if (ncontig) { 262 ncontig = min(ncontig + 1, racluster); 263 rbp = cluster_rbuild(vp, filesize, lblkno, blkno, 264 size, ncontig, gbflags, NULL); 265 lblkno += (rbp->b_bufsize / size); 266 if (rbp->b_flags & B_DELWRI) { 267 bqrelse(rbp); 268 continue; 269 } 270 } else { 271 rbp = getblk(vp, lblkno, size, 0, 0, gbflags); 272 lblkno += 1; 273 if (rbp->b_flags & B_DELWRI) { 274 bqrelse(rbp); 275 continue; 276 } 277 rbp->b_flags |= B_ASYNC | B_RAM; 278 rbp->b_iocmd = BIO_READ; 279 rbp->b_blkno = blkno; 280 } 281 if (rbp->b_flags & B_CACHE) { 282 rbp->b_flags &= ~B_ASYNC; 283 bqrelse(rbp); 284 continue; 285 } 286 if ((rbp->b_flags & B_CLUSTER) == 0) { 287 vfs_busy_pages(rbp, 0); 288 } 289 rbp->b_flags &= ~B_INVAL; 290 rbp->b_ioflags &= ~BIO_ERROR; 291 if ((rbp->b_flags & B_ASYNC) || rbp->b_iodone != NULL) 292 BUF_KERNPROC(rbp); 293 rbp->b_iooffset = dbtob(rbp->b_blkno); 294 bstrategy(rbp); 295 curthread->td_ru.ru_inblock++; 296 } 297 298 if (reqbp) 299 return (bufwait(reqbp)); 300 else 301 return (error); 302 } 303 304 /* 305 * If blocks are contiguous on disk, use this to provide clustered 306 * read ahead. We will read as many blocks as possible sequentially 307 * and then parcel them up into logical blocks in the buffer hash table. 308 */ 309 static struct buf * 310 cluster_rbuild(struct vnode *vp, u_quad_t filesize, daddr_t lbn, 311 daddr_t blkno, long size, int run, int gbflags, struct buf *fbp) 312 { 313 struct bufobj *bo; 314 struct buf *bp, *tbp; 315 daddr_t bn; 316 off_t off; 317 long tinc, tsize; 318 int i, inc, j, k, toff; 319 320 KASSERT(size == vp->v_mount->mnt_stat.f_iosize, 321 ("cluster_rbuild: size %ld != f_iosize %jd\n", 322 size, (intmax_t)vp->v_mount->mnt_stat.f_iosize)); 323 324 /* 325 * avoid a division 326 */ 327 while ((u_quad_t) size * (lbn + run) > filesize) { 328 --run; 329 } 330 331 if (fbp) { 332 tbp = fbp; 333 tbp->b_iocmd = BIO_READ; 334 } else { 335 tbp = getblk(vp, lbn, size, 0, 0, gbflags); 336 if (tbp->b_flags & B_CACHE) 337 return tbp; 338 tbp->b_flags |= B_ASYNC | B_RAM; 339 tbp->b_iocmd = BIO_READ; 340 } 341 tbp->b_blkno = blkno; 342 if( (tbp->b_flags & B_MALLOC) || 343 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1) ) 344 return tbp; 345 346 bp = trypbuf(&cluster_pbuf_freecnt); 347 if (bp == 0) 348 return tbp; 349 350 /* 351 * We are synthesizing a buffer out of vm_page_t's, but 352 * if the block size is not page aligned then the starting 353 * address may not be either. Inherit the b_data offset 354 * from the original buffer. 355 */ 356 bp->b_flags = B_ASYNC | B_CLUSTER | B_VMIO; 357 if ((gbflags & GB_UNMAPPED) != 0) { 358 bp->b_flags |= B_UNMAPPED; 359 bp->b_data = unmapped_buf; 360 } else { 361 bp->b_data = (char *)((vm_offset_t)bp->b_data | 362 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 363 } 364 bp->b_iocmd = BIO_READ; 365 bp->b_iodone = cluster_callback; 366 bp->b_blkno = blkno; 367 bp->b_lblkno = lbn; 368 bp->b_offset = tbp->b_offset; 369 KASSERT(bp->b_offset != NOOFFSET, ("cluster_rbuild: no buffer offset")); 370 pbgetvp(vp, bp); 371 372 TAILQ_INIT(&bp->b_cluster.cluster_head); 373 374 bp->b_bcount = 0; 375 bp->b_bufsize = 0; 376 bp->b_npages = 0; 377 378 inc = btodb(size); 379 bo = &vp->v_bufobj; 380 for (bn = blkno, i = 0; i < run; ++i, bn += inc) { 381 if (i == 0) { 382 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object); 383 vfs_drain_busy_pages(tbp); 384 vm_object_pip_add(tbp->b_bufobj->bo_object, 385 tbp->b_npages); 386 for (k = 0; k < tbp->b_npages; k++) 387 vm_page_sbusy(tbp->b_pages[k]); 388 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object); 389 } else { 390 if ((bp->b_npages * PAGE_SIZE) + 391 round_page(size) > vp->v_mount->mnt_iosize_max) { 392 break; 393 } 394 395 tbp = getblk(vp, lbn + i, size, 0, 0, GB_LOCK_NOWAIT | 396 (gbflags & GB_UNMAPPED)); 397 398 /* Don't wait around for locked bufs. */ 399 if (tbp == NULL) 400 break; 401 402 /* 403 * Stop scanning if the buffer is fully valid 404 * (marked B_CACHE), or locked (may be doing a 405 * background write), or if the buffer is not 406 * VMIO backed. The clustering code can only deal 407 * with VMIO-backed buffers. The bo lock is not 408 * required for the BKGRDINPROG check since it 409 * can not be set without the buf lock. 410 */ 411 if ((tbp->b_vflags & BV_BKGRDINPROG) || 412 (tbp->b_flags & B_CACHE) || 413 (tbp->b_flags & B_VMIO) == 0) { 414 bqrelse(tbp); 415 break; 416 } 417 418 /* 419 * The buffer must be completely invalid in order to 420 * take part in the cluster. If it is partially valid 421 * then we stop. 422 */ 423 off = tbp->b_offset; 424 tsize = size; 425 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object); 426 for (j = 0; tsize > 0; j++) { 427 toff = off & PAGE_MASK; 428 tinc = tsize; 429 if (toff + tinc > PAGE_SIZE) 430 tinc = PAGE_SIZE - toff; 431 VM_OBJECT_ASSERT_WLOCKED(tbp->b_pages[j]->object); 432 if ((tbp->b_pages[j]->valid & 433 vm_page_bits(toff, tinc)) != 0) 434 break; 435 if (vm_page_xbusied(tbp->b_pages[j])) 436 break; 437 vm_object_pip_add(tbp->b_bufobj->bo_object, 1); 438 vm_page_sbusy(tbp->b_pages[j]); 439 off += tinc; 440 tsize -= tinc; 441 } 442 if (tsize > 0) { 443 clean_sbusy: 444 vm_object_pip_add(tbp->b_bufobj->bo_object, -j); 445 for (k = 0; k < j; k++) 446 vm_page_sunbusy(tbp->b_pages[k]); 447 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object); 448 bqrelse(tbp); 449 break; 450 } 451 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object); 452 453 /* 454 * Set a read-ahead mark as appropriate 455 */ 456 if ((fbp && (i == 1)) || (i == (run - 1))) 457 tbp->b_flags |= B_RAM; 458 459 /* 460 * Set the buffer up for an async read (XXX should 461 * we do this only if we do not wind up brelse()ing?). 462 * Set the block number if it isn't set, otherwise 463 * if it is make sure it matches the block number we 464 * expect. 465 */ 466 tbp->b_flags |= B_ASYNC; 467 tbp->b_iocmd = BIO_READ; 468 if (tbp->b_blkno == tbp->b_lblkno) { 469 tbp->b_blkno = bn; 470 } else if (tbp->b_blkno != bn) { 471 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object); 472 goto clean_sbusy; 473 } 474 } 475 /* 476 * XXX fbp from caller may not be B_ASYNC, but we are going 477 * to biodone() it in cluster_callback() anyway 478 */ 479 BUF_KERNPROC(tbp); 480 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head, 481 tbp, b_cluster.cluster_entry); 482 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object); 483 for (j = 0; j < tbp->b_npages; j += 1) { 484 vm_page_t m; 485 m = tbp->b_pages[j]; 486 if ((bp->b_npages == 0) || 487 (bp->b_pages[bp->b_npages-1] != m)) { 488 bp->b_pages[bp->b_npages] = m; 489 bp->b_npages++; 490 } 491 if (m->valid == VM_PAGE_BITS_ALL) 492 tbp->b_pages[j] = bogus_page; 493 } 494 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object); 495 /* 496 * Don't inherit tbp->b_bufsize as it may be larger due to 497 * a non-page-aligned size. Instead just aggregate using 498 * 'size'. 499 */ 500 if (tbp->b_bcount != size) 501 printf("warning: tbp->b_bcount wrong %ld vs %ld\n", tbp->b_bcount, size); 502 if (tbp->b_bufsize != size) 503 printf("warning: tbp->b_bufsize wrong %ld vs %ld\n", tbp->b_bufsize, size); 504 bp->b_bcount += size; 505 bp->b_bufsize += size; 506 } 507 508 /* 509 * Fully valid pages in the cluster are already good and do not need 510 * to be re-read from disk. Replace the page with bogus_page 511 */ 512 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 513 for (j = 0; j < bp->b_npages; j++) { 514 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[j]->object); 515 if (bp->b_pages[j]->valid == VM_PAGE_BITS_ALL) 516 bp->b_pages[j] = bogus_page; 517 } 518 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 519 if (bp->b_bufsize > bp->b_kvasize) 520 panic("cluster_rbuild: b_bufsize(%ld) > b_kvasize(%d)\n", 521 bp->b_bufsize, bp->b_kvasize); 522 bp->b_kvasize = bp->b_bufsize; 523 524 if ((bp->b_flags & B_UNMAPPED) == 0) { 525 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 526 (vm_page_t *)bp->b_pages, bp->b_npages); 527 } 528 return (bp); 529 } 530 531 /* 532 * Cleanup after a clustered read or write. 533 * This is complicated by the fact that any of the buffers might have 534 * extra memory (if there were no empty buffer headers at allocbuf time) 535 * that we will need to shift around. 536 */ 537 static void 538 cluster_callback(bp) 539 struct buf *bp; 540 { 541 struct buf *nbp, *tbp; 542 int error = 0; 543 544 /* 545 * Must propogate errors to all the components. 546 */ 547 if (bp->b_ioflags & BIO_ERROR) 548 error = bp->b_error; 549 550 if ((bp->b_flags & B_UNMAPPED) == 0) { 551 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), 552 bp->b_npages); 553 } 554 /* 555 * Move memory from the large cluster buffer into the component 556 * buffers and mark IO as done on these. 557 */ 558 for (tbp = TAILQ_FIRST(&bp->b_cluster.cluster_head); 559 tbp; tbp = nbp) { 560 nbp = TAILQ_NEXT(&tbp->b_cluster, cluster_entry); 561 if (error) { 562 tbp->b_ioflags |= BIO_ERROR; 563 tbp->b_error = error; 564 } else { 565 tbp->b_dirtyoff = tbp->b_dirtyend = 0; 566 tbp->b_flags &= ~B_INVAL; 567 tbp->b_ioflags &= ~BIO_ERROR; 568 /* 569 * XXX the bdwrite()/bqrelse() issued during 570 * cluster building clears B_RELBUF (see bqrelse() 571 * comment). If direct I/O was specified, we have 572 * to restore it here to allow the buffer and VM 573 * to be freed. 574 */ 575 if (tbp->b_flags & B_DIRECT) 576 tbp->b_flags |= B_RELBUF; 577 } 578 bufdone(tbp); 579 } 580 pbrelvp(bp); 581 relpbuf(bp, &cluster_pbuf_freecnt); 582 } 583 584 /* 585 * cluster_wbuild_wb: 586 * 587 * Implement modified write build for cluster. 588 * 589 * write_behind = 0 write behind disabled 590 * write_behind = 1 write behind normal (default) 591 * write_behind = 2 write behind backed-off 592 */ 593 594 static __inline int 595 cluster_wbuild_wb(struct vnode *vp, long size, daddr_t start_lbn, int len, 596 int gbflags) 597 { 598 int r = 0; 599 600 switch (write_behind) { 601 case 2: 602 if (start_lbn < len) 603 break; 604 start_lbn -= len; 605 /* FALLTHROUGH */ 606 case 1: 607 r = cluster_wbuild(vp, size, start_lbn, len, gbflags); 608 /* FALLTHROUGH */ 609 default: 610 /* FALLTHROUGH */ 611 break; 612 } 613 return(r); 614 } 615 616 /* 617 * Do clustered write for FFS. 618 * 619 * Three cases: 620 * 1. Write is not sequential (write asynchronously) 621 * Write is sequential: 622 * 2. beginning of cluster - begin cluster 623 * 3. middle of a cluster - add to cluster 624 * 4. end of a cluster - asynchronously write cluster 625 */ 626 void 627 cluster_write(struct vnode *vp, struct buf *bp, u_quad_t filesize, int seqcount, 628 int gbflags) 629 { 630 daddr_t lbn; 631 int maxclen, cursize; 632 int lblocksize; 633 int async; 634 635 if (!unmapped_buf_allowed) 636 gbflags &= ~GB_UNMAPPED; 637 638 if (vp->v_type == VREG) { 639 async = DOINGASYNC(vp); 640 lblocksize = vp->v_mount->mnt_stat.f_iosize; 641 } else { 642 async = 0; 643 lblocksize = bp->b_bufsize; 644 } 645 lbn = bp->b_lblkno; 646 KASSERT(bp->b_offset != NOOFFSET, ("cluster_write: no buffer offset")); 647 648 /* Initialize vnode to beginning of file. */ 649 if (lbn == 0) 650 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0; 651 652 if (vp->v_clen == 0 || lbn != vp->v_lastw + 1 || 653 (bp->b_blkno != vp->v_lasta + btodb(lblocksize))) { 654 maxclen = vp->v_mount->mnt_iosize_max / lblocksize - 1; 655 if (vp->v_clen != 0) { 656 /* 657 * Next block is not sequential. 658 * 659 * If we are not writing at end of file, the process 660 * seeked to another point in the file since its last 661 * write, or we have reached our maximum cluster size, 662 * then push the previous cluster. Otherwise try 663 * reallocating to make it sequential. 664 * 665 * Change to algorithm: only push previous cluster if 666 * it was sequential from the point of view of the 667 * seqcount heuristic, otherwise leave the buffer 668 * intact so we can potentially optimize the I/O 669 * later on in the buf_daemon or update daemon 670 * flush. 671 */ 672 cursize = vp->v_lastw - vp->v_cstart + 1; 673 if (((u_quad_t) bp->b_offset + lblocksize) != filesize || 674 lbn != vp->v_lastw + 1 || vp->v_clen <= cursize) { 675 if (!async && seqcount > 0) { 676 cluster_wbuild_wb(vp, lblocksize, 677 vp->v_cstart, cursize, gbflags); 678 } 679 } else { 680 struct buf **bpp, **endbp; 681 struct cluster_save *buflist; 682 683 buflist = cluster_collectbufs(vp, bp, gbflags); 684 endbp = &buflist->bs_children 685 [buflist->bs_nchildren - 1]; 686 if (VOP_REALLOCBLKS(vp, buflist)) { 687 /* 688 * Failed, push the previous cluster 689 * if *really* writing sequentially 690 * in the logical file (seqcount > 1), 691 * otherwise delay it in the hopes that 692 * the low level disk driver can 693 * optimize the write ordering. 694 */ 695 for (bpp = buflist->bs_children; 696 bpp < endbp; bpp++) 697 brelse(*bpp); 698 free(buflist, M_SEGMENT); 699 if (seqcount > 1) { 700 cluster_wbuild_wb(vp, 701 lblocksize, vp->v_cstart, 702 cursize, gbflags); 703 } 704 } else { 705 /* 706 * Succeeded, keep building cluster. 707 */ 708 for (bpp = buflist->bs_children; 709 bpp <= endbp; bpp++) 710 bdwrite(*bpp); 711 free(buflist, M_SEGMENT); 712 vp->v_lastw = lbn; 713 vp->v_lasta = bp->b_blkno; 714 return; 715 } 716 } 717 } 718 /* 719 * Consider beginning a cluster. If at end of file, make 720 * cluster as large as possible, otherwise find size of 721 * existing cluster. 722 */ 723 if ((vp->v_type == VREG) && 724 ((u_quad_t) bp->b_offset + lblocksize) != filesize && 725 (bp->b_blkno == bp->b_lblkno) && 726 (VOP_BMAP(vp, lbn, NULL, &bp->b_blkno, &maxclen, NULL) || 727 bp->b_blkno == -1)) { 728 bawrite(bp); 729 vp->v_clen = 0; 730 vp->v_lasta = bp->b_blkno; 731 vp->v_cstart = lbn + 1; 732 vp->v_lastw = lbn; 733 return; 734 } 735 vp->v_clen = maxclen; 736 if (!async && maxclen == 0) { /* I/O not contiguous */ 737 vp->v_cstart = lbn + 1; 738 bawrite(bp); 739 } else { /* Wait for rest of cluster */ 740 vp->v_cstart = lbn; 741 bdwrite(bp); 742 } 743 } else if (lbn == vp->v_cstart + vp->v_clen) { 744 /* 745 * At end of cluster, write it out if seqcount tells us we 746 * are operating sequentially, otherwise let the buf or 747 * update daemon handle it. 748 */ 749 bdwrite(bp); 750 if (seqcount > 1) { 751 cluster_wbuild_wb(vp, lblocksize, vp->v_cstart, 752 vp->v_clen + 1, gbflags); 753 } 754 vp->v_clen = 0; 755 vp->v_cstart = lbn + 1; 756 } else if (vm_page_count_severe()) { 757 /* 758 * We are low on memory, get it going NOW 759 */ 760 bawrite(bp); 761 } else { 762 /* 763 * In the middle of a cluster, so just delay the I/O for now. 764 */ 765 bdwrite(bp); 766 } 767 vp->v_lastw = lbn; 768 vp->v_lasta = bp->b_blkno; 769 } 770 771 772 /* 773 * This is an awful lot like cluster_rbuild...wish they could be combined. 774 * The last lbn argument is the current block on which I/O is being 775 * performed. Check to see that it doesn't fall in the middle of 776 * the current block (if last_bp == NULL). 777 */ 778 int 779 cluster_wbuild(struct vnode *vp, long size, daddr_t start_lbn, int len, 780 int gbflags) 781 { 782 struct buf *bp, *tbp; 783 struct bufobj *bo; 784 int i, j; 785 int totalwritten = 0; 786 int dbsize = btodb(size); 787 788 if (!unmapped_buf_allowed) 789 gbflags &= ~GB_UNMAPPED; 790 791 bo = &vp->v_bufobj; 792 while (len > 0) { 793 /* 794 * If the buffer is not delayed-write (i.e. dirty), or it 795 * is delayed-write but either locked or inval, it cannot 796 * partake in the clustered write. 797 */ 798 BO_LOCK(bo); 799 if ((tbp = gbincore(&vp->v_bufobj, start_lbn)) == NULL || 800 (tbp->b_vflags & BV_BKGRDINPROG)) { 801 BO_UNLOCK(bo); 802 ++start_lbn; 803 --len; 804 continue; 805 } 806 if (BUF_LOCK(tbp, 807 LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, BO_LOCKPTR(bo))) { 808 ++start_lbn; 809 --len; 810 continue; 811 } 812 if ((tbp->b_flags & (B_INVAL | B_DELWRI)) != B_DELWRI) { 813 BUF_UNLOCK(tbp); 814 ++start_lbn; 815 --len; 816 continue; 817 } 818 if (tbp->b_pin_count > 0) { 819 BUF_UNLOCK(tbp); 820 ++start_lbn; 821 --len; 822 continue; 823 } 824 bremfree(tbp); 825 tbp->b_flags &= ~B_DONE; 826 827 /* 828 * Extra memory in the buffer, punt on this buffer. 829 * XXX we could handle this in most cases, but we would 830 * have to push the extra memory down to after our max 831 * possible cluster size and then potentially pull it back 832 * up if the cluster was terminated prematurely--too much 833 * hassle. 834 */ 835 if (((tbp->b_flags & (B_CLUSTEROK | B_MALLOC | B_VMIO)) != 836 (B_CLUSTEROK | B_VMIO)) || 837 (tbp->b_bcount != tbp->b_bufsize) || 838 (tbp->b_bcount != size) || 839 (len == 1) || 840 ((bp = (vp->v_vflag & VV_MD) != 0 ? 841 trypbuf(&cluster_pbuf_freecnt) : 842 getpbuf(&cluster_pbuf_freecnt)) == NULL)) { 843 totalwritten += tbp->b_bufsize; 844 bawrite(tbp); 845 ++start_lbn; 846 --len; 847 continue; 848 } 849 850 /* 851 * We got a pbuf to make the cluster in. 852 * so initialise it. 853 */ 854 TAILQ_INIT(&bp->b_cluster.cluster_head); 855 bp->b_bcount = 0; 856 bp->b_bufsize = 0; 857 bp->b_npages = 0; 858 if (tbp->b_wcred != NOCRED) 859 bp->b_wcred = crhold(tbp->b_wcred); 860 861 bp->b_blkno = tbp->b_blkno; 862 bp->b_lblkno = tbp->b_lblkno; 863 bp->b_offset = tbp->b_offset; 864 865 /* 866 * We are synthesizing a buffer out of vm_page_t's, but 867 * if the block size is not page aligned then the starting 868 * address may not be either. Inherit the b_data offset 869 * from the original buffer. 870 */ 871 if ((gbflags & GB_UNMAPPED) == 0 || 872 (tbp->b_flags & B_VMIO) == 0) { 873 bp->b_data = (char *)((vm_offset_t)bp->b_data | 874 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 875 } else { 876 bp->b_flags |= B_UNMAPPED; 877 bp->b_data = unmapped_buf; 878 } 879 bp->b_flags |= B_CLUSTER | (tbp->b_flags & (B_VMIO | 880 B_NEEDCOMMIT)); 881 bp->b_iodone = cluster_callback; 882 pbgetvp(vp, bp); 883 /* 884 * From this location in the file, scan forward to see 885 * if there are buffers with adjacent data that need to 886 * be written as well. 887 */ 888 for (i = 0; i < len; ++i, ++start_lbn) { 889 if (i != 0) { /* If not the first buffer */ 890 /* 891 * If the adjacent data is not even in core it 892 * can't need to be written. 893 */ 894 BO_LOCK(bo); 895 if ((tbp = gbincore(bo, start_lbn)) == NULL || 896 (tbp->b_vflags & BV_BKGRDINPROG)) { 897 BO_UNLOCK(bo); 898 break; 899 } 900 901 /* 902 * If it IS in core, but has different 903 * characteristics, or is locked (which 904 * means it could be undergoing a background 905 * I/O or be in a weird state), then don't 906 * cluster with it. 907 */ 908 if (BUF_LOCK(tbp, 909 LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, 910 BO_LOCKPTR(bo))) 911 break; 912 913 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK | 914 B_INVAL | B_DELWRI | B_NEEDCOMMIT)) 915 != (B_DELWRI | B_CLUSTEROK | 916 (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) || 917 tbp->b_wcred != bp->b_wcred) { 918 BUF_UNLOCK(tbp); 919 break; 920 } 921 922 /* 923 * Check that the combined cluster 924 * would make sense with regard to pages 925 * and would not be too large 926 */ 927 if ((tbp->b_bcount != size) || 928 ((bp->b_blkno + (dbsize * i)) != 929 tbp->b_blkno) || 930 ((tbp->b_npages + bp->b_npages) > 931 (vp->v_mount->mnt_iosize_max / PAGE_SIZE))) { 932 BUF_UNLOCK(tbp); 933 break; 934 } 935 936 /* 937 * Do not pull in pinned buffers. 938 */ 939 if (tbp->b_pin_count > 0) { 940 BUF_UNLOCK(tbp); 941 break; 942 } 943 944 /* 945 * Ok, it's passed all the tests, 946 * so remove it from the free list 947 * and mark it busy. We will use it. 948 */ 949 bremfree(tbp); 950 tbp->b_flags &= ~B_DONE; 951 } /* end of code for non-first buffers only */ 952 /* 953 * If the IO is via the VM then we do some 954 * special VM hackery (yuck). Since the buffer's 955 * block size may not be page-aligned it is possible 956 * for a page to be shared between two buffers. We 957 * have to get rid of the duplication when building 958 * the cluster. 959 */ 960 if (tbp->b_flags & B_VMIO) { 961 vm_page_t m; 962 963 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object); 964 if (i == 0) { 965 vfs_drain_busy_pages(tbp); 966 } else { /* if not first buffer */ 967 for (j = 0; j < tbp->b_npages; j += 1) { 968 m = tbp->b_pages[j]; 969 if (vm_page_xbusied(m)) { 970 VM_OBJECT_WUNLOCK( 971 tbp->b_object); 972 bqrelse(tbp); 973 goto finishcluster; 974 } 975 } 976 } 977 for (j = 0; j < tbp->b_npages; j += 1) { 978 m = tbp->b_pages[j]; 979 vm_page_sbusy(m); 980 vm_object_pip_add(m->object, 1); 981 if ((bp->b_npages == 0) || 982 (bp->b_pages[bp->b_npages - 1] != m)) { 983 bp->b_pages[bp->b_npages] = m; 984 bp->b_npages++; 985 } 986 } 987 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object); 988 } 989 bp->b_bcount += size; 990 bp->b_bufsize += size; 991 /* 992 * If any of the clustered buffers have their 993 * B_BARRIER flag set, transfer that request to 994 * the cluster. 995 */ 996 bp->b_flags |= (tbp->b_flags & B_BARRIER); 997 tbp->b_flags &= ~(B_DONE | B_BARRIER); 998 tbp->b_flags |= B_ASYNC; 999 tbp->b_ioflags &= ~BIO_ERROR; 1000 tbp->b_iocmd = BIO_WRITE; 1001 bundirty(tbp); 1002 reassignbuf(tbp); /* put on clean list */ 1003 bufobj_wref(tbp->b_bufobj); 1004 BUF_KERNPROC(tbp); 1005 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head, 1006 tbp, b_cluster.cluster_entry); 1007 } 1008 finishcluster: 1009 if ((bp->b_flags & B_UNMAPPED) == 0) { 1010 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 1011 (vm_page_t *)bp->b_pages, bp->b_npages); 1012 } 1013 if (bp->b_bufsize > bp->b_kvasize) 1014 panic( 1015 "cluster_wbuild: b_bufsize(%ld) > b_kvasize(%d)\n", 1016 bp->b_bufsize, bp->b_kvasize); 1017 bp->b_kvasize = bp->b_bufsize; 1018 totalwritten += bp->b_bufsize; 1019 bp->b_dirtyoff = 0; 1020 bp->b_dirtyend = bp->b_bufsize; 1021 bawrite(bp); 1022 1023 len -= i; 1024 } 1025 return totalwritten; 1026 } 1027 1028 /* 1029 * Collect together all the buffers in a cluster. 1030 * Plus add one additional buffer. 1031 */ 1032 static struct cluster_save * 1033 cluster_collectbufs(struct vnode *vp, struct buf *last_bp, int gbflags) 1034 { 1035 struct cluster_save *buflist; 1036 struct buf *bp; 1037 daddr_t lbn; 1038 int i, len; 1039 1040 len = vp->v_lastw - vp->v_cstart + 1; 1041 buflist = malloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist), 1042 M_SEGMENT, M_WAITOK); 1043 buflist->bs_nchildren = 0; 1044 buflist->bs_children = (struct buf **) (buflist + 1); 1045 for (lbn = vp->v_cstart, i = 0; i < len; lbn++, i++) { 1046 (void)bread_gb(vp, lbn, last_bp->b_bcount, NOCRED, 1047 gbflags, &bp); 1048 buflist->bs_children[i] = bp; 1049 if (bp->b_blkno == bp->b_lblkno) 1050 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, 1051 NULL, NULL); 1052 } 1053 buflist->bs_children[i] = bp = last_bp; 1054 if (bp->b_blkno == bp->b_lblkno) 1055 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 1056 buflist->bs_nchildren = i + 1; 1057 return (buflist); 1058 }
Cache object: 5b80bad0c3e5d34a3bfb432c372909b5
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