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/9.2/sys/kern/vfs_cluster.c 251897 2013-06-18 05:21:40Z scottl $"); 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/vmmeter.h> 50 #include <vm/vm.h> 51 #include <vm/vm_object.h> 52 #include <vm/vm_page.h> 53 #include <sys/sysctl.h> 54 55 #if defined(CLUSTERDEBUG) 56 static int rcluster= 0; 57 SYSCTL_INT(_debug, OID_AUTO, rcluster, CTLFLAG_RW, &rcluster, 0, 58 "Debug VFS clustering code"); 59 #endif 60 61 static MALLOC_DEFINE(M_SEGMENT, "cl_savebuf", "cluster_save buffer"); 62 63 static struct cluster_save *cluster_collectbufs(struct vnode *vp, 64 struct buf *last_bp, int gbflags); 65 static struct buf *cluster_rbuild(struct vnode *vp, u_quad_t filesize, 66 daddr_t lbn, daddr_t blkno, long size, int run, int gbflags, 67 struct buf *fbp); 68 static void cluster_callback(struct buf *); 69 70 static int write_behind = 1; 71 SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0, 72 "Cluster write-behind; 0: disable, 1: enable, 2: backed off"); 73 74 static int read_max = 64; 75 SYSCTL_INT(_vfs, OID_AUTO, read_max, CTLFLAG_RW, &read_max, 0, 76 "Cluster read-ahead max block count"); 77 78 static int read_min = 1; 79 SYSCTL_INT(_vfs, OID_AUTO, read_min, CTLFLAG_RW, &read_min, 0, 80 "Cluster read min block count"); 81 82 /* Page expended to mark partially backed buffers */ 83 extern vm_page_t bogus_page; 84 85 /* 86 * Read data to a buf, including read-ahead if we find this to be beneficial. 87 * cluster_read replaces bread. 88 */ 89 int 90 cluster_read(struct vnode *vp, u_quad_t filesize, daddr_t lblkno, long size, 91 struct ucred *cred, long totread, int seqcount, struct buf **bpp) 92 { 93 94 return (cluster_read_gb(vp, filesize, lblkno, size, cred, totread, 95 seqcount, 0, bpp)); 96 } 97 98 int 99 cluster_read_gb(struct vnode *vp, u_quad_t filesize, daddr_t lblkno, long size, 100 struct ucred *cred, long totread, int seqcount, int gbflags, 101 struct buf **bpp) 102 { 103 struct buf *bp, *rbp, *reqbp; 104 struct bufobj *bo; 105 daddr_t blkno, origblkno; 106 int maxra, racluster; 107 int error, ncontig; 108 int i; 109 110 error = 0; 111 bo = &vp->v_bufobj; 112 if (!unmapped_buf_allowed) 113 gbflags &= ~GB_UNMAPPED; 114 115 /* 116 * Try to limit the amount of read-ahead by a few 117 * ad-hoc parameters. This needs work!!! 118 */ 119 racluster = vp->v_mount->mnt_iosize_max / size; 120 maxra = seqcount; 121 maxra = min(read_max, maxra); 122 maxra = min(nbuf/8, maxra); 123 if (((u_quad_t)(lblkno + maxra + 1) * size) > filesize) 124 maxra = (filesize / size) - lblkno; 125 126 /* 127 * get the requested block 128 */ 129 *bpp = reqbp = bp = getblk(vp, lblkno, size, 0, 0, gbflags); 130 origblkno = lblkno; 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_LOCK(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_UNLOCK(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 curthread->td_ru.ru_inblock++; 251 } 252 253 /* 254 * If we have been doing sequential I/O, then do some read-ahead. 255 */ 256 while (lblkno < (origblkno + maxra)) { 257 error = VOP_BMAP(vp, lblkno, NULL, &blkno, &ncontig, NULL); 258 if (error) 259 break; 260 261 if (blkno == -1) 262 break; 263 264 /* 265 * We could throttle ncontig here by maxra but we might as 266 * well read the data if it is contiguous. We're throttled 267 * by racluster anyway. 268 */ 269 if (ncontig) { 270 ncontig = min(ncontig + 1, racluster); 271 rbp = cluster_rbuild(vp, filesize, lblkno, blkno, 272 size, ncontig, gbflags, NULL); 273 lblkno += (rbp->b_bufsize / size); 274 if (rbp->b_flags & B_DELWRI) { 275 bqrelse(rbp); 276 continue; 277 } 278 } else { 279 rbp = getblk(vp, lblkno, size, 0, 0, gbflags); 280 lblkno += 1; 281 if (rbp->b_flags & B_DELWRI) { 282 bqrelse(rbp); 283 continue; 284 } 285 rbp->b_flags |= B_ASYNC | B_RAM; 286 rbp->b_iocmd = BIO_READ; 287 rbp->b_blkno = blkno; 288 } 289 if (rbp->b_flags & B_CACHE) { 290 rbp->b_flags &= ~B_ASYNC; 291 bqrelse(rbp); 292 continue; 293 } 294 if ((rbp->b_flags & B_CLUSTER) == 0) { 295 vfs_busy_pages(rbp, 0); 296 } 297 rbp->b_flags &= ~B_INVAL; 298 rbp->b_ioflags &= ~BIO_ERROR; 299 if ((rbp->b_flags & B_ASYNC) || rbp->b_iodone != NULL) 300 BUF_KERNPROC(rbp); 301 rbp->b_iooffset = dbtob(rbp->b_blkno); 302 bstrategy(rbp); 303 curthread->td_ru.ru_inblock++; 304 } 305 306 if (reqbp) 307 return (bufwait(reqbp)); 308 else 309 return (error); 310 } 311 312 /* 313 * If blocks are contiguous on disk, use this to provide clustered 314 * read ahead. We will read as many blocks as possible sequentially 315 * and then parcel them up into logical blocks in the buffer hash table. 316 */ 317 static struct buf * 318 cluster_rbuild(struct vnode *vp, u_quad_t filesize, daddr_t lbn, 319 daddr_t blkno, long size, int run, int gbflags, struct buf *fbp) 320 { 321 struct bufobj *bo; 322 struct buf *bp, *tbp; 323 daddr_t bn; 324 off_t off; 325 long tinc, tsize; 326 int i, inc, j, toff; 327 328 KASSERT(size == vp->v_mount->mnt_stat.f_iosize, 329 ("cluster_rbuild: size %ld != filesize %jd\n", 330 size, (intmax_t)vp->v_mount->mnt_stat.f_iosize)); 331 332 /* 333 * avoid a division 334 */ 335 while ((u_quad_t) size * (lbn + run) > filesize) { 336 --run; 337 } 338 339 if (fbp) { 340 tbp = fbp; 341 tbp->b_iocmd = BIO_READ; 342 } else { 343 tbp = getblk(vp, lbn, size, 0, 0, gbflags); 344 if (tbp->b_flags & B_CACHE) 345 return tbp; 346 tbp->b_flags |= B_ASYNC | B_RAM; 347 tbp->b_iocmd = BIO_READ; 348 } 349 tbp->b_blkno = blkno; 350 if( (tbp->b_flags & B_MALLOC) || 351 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1) ) 352 return tbp; 353 354 bp = trypbuf(&cluster_pbuf_freecnt); 355 if (bp == 0) 356 return tbp; 357 358 /* 359 * We are synthesizing a buffer out of vm_page_t's, but 360 * if the block size is not page aligned then the starting 361 * address may not be either. Inherit the b_data offset 362 * from the original buffer. 363 */ 364 bp->b_flags = B_ASYNC | B_CLUSTER | B_VMIO; 365 if ((gbflags & GB_UNMAPPED) != 0) { 366 bp->b_flags |= B_UNMAPPED; 367 bp->b_data = unmapped_buf; 368 } else { 369 bp->b_data = (char *)((vm_offset_t)bp->b_data | 370 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 371 } 372 bp->b_iocmd = BIO_READ; 373 bp->b_iodone = cluster_callback; 374 bp->b_blkno = blkno; 375 bp->b_lblkno = lbn; 376 bp->b_offset = tbp->b_offset; 377 KASSERT(bp->b_offset != NOOFFSET, ("cluster_rbuild: no buffer offset")); 378 pbgetvp(vp, bp); 379 380 TAILQ_INIT(&bp->b_cluster.cluster_head); 381 382 bp->b_bcount = 0; 383 bp->b_bufsize = 0; 384 bp->b_npages = 0; 385 386 inc = btodb(size); 387 bo = &vp->v_bufobj; 388 for (bn = blkno, i = 0; i < run; ++i, bn += inc) { 389 if (i != 0) { 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. 408 */ 409 BO_LOCK(bo); 410 if ((tbp->b_vflags & BV_BKGRDINPROG) || 411 (tbp->b_flags & B_CACHE) || 412 (tbp->b_flags & B_VMIO) == 0) { 413 BO_UNLOCK(bo); 414 bqrelse(tbp); 415 break; 416 } 417 BO_UNLOCK(bo); 418 419 /* 420 * The buffer must be completely invalid in order to 421 * take part in the cluster. If it is partially valid 422 * then we stop. 423 */ 424 off = tbp->b_offset; 425 tsize = size; 426 VM_OBJECT_LOCK(tbp->b_bufobj->bo_object); 427 for (j = 0; tsize > 0; j++) { 428 toff = off & PAGE_MASK; 429 tinc = tsize; 430 if (toff + tinc > PAGE_SIZE) 431 tinc = PAGE_SIZE - toff; 432 VM_OBJECT_LOCK_ASSERT(tbp->b_pages[j]->object, 433 MA_OWNED); 434 if ((tbp->b_pages[j]->valid & 435 vm_page_bits(toff, tinc)) != 0) 436 break; 437 off += tinc; 438 tsize -= tinc; 439 } 440 VM_OBJECT_UNLOCK(tbp->b_bufobj->bo_object); 441 if (tsize > 0) { 442 bqrelse(tbp); 443 break; 444 } 445 446 /* 447 * Set a read-ahead mark as appropriate 448 */ 449 if ((fbp && (i == 1)) || (i == (run - 1))) 450 tbp->b_flags |= B_RAM; 451 452 /* 453 * Set the buffer up for an async read (XXX should 454 * we do this only if we do not wind up brelse()ing?). 455 * Set the block number if it isn't set, otherwise 456 * if it is make sure it matches the block number we 457 * expect. 458 */ 459 tbp->b_flags |= B_ASYNC; 460 tbp->b_iocmd = BIO_READ; 461 if (tbp->b_blkno == tbp->b_lblkno) { 462 tbp->b_blkno = bn; 463 } else if (tbp->b_blkno != bn) { 464 brelse(tbp); 465 break; 466 } 467 } 468 /* 469 * XXX fbp from caller may not be B_ASYNC, but we are going 470 * to biodone() it in cluster_callback() anyway 471 */ 472 BUF_KERNPROC(tbp); 473 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head, 474 tbp, b_cluster.cluster_entry); 475 VM_OBJECT_LOCK(tbp->b_bufobj->bo_object); 476 for (j = 0; j < tbp->b_npages; j += 1) { 477 vm_page_t m; 478 m = tbp->b_pages[j]; 479 vm_page_io_start(m); 480 vm_object_pip_add(m->object, 1); 481 if ((bp->b_npages == 0) || 482 (bp->b_pages[bp->b_npages-1] != m)) { 483 bp->b_pages[bp->b_npages] = m; 484 bp->b_npages++; 485 } 486 if (m->valid == VM_PAGE_BITS_ALL) 487 tbp->b_pages[j] = bogus_page; 488 } 489 VM_OBJECT_UNLOCK(tbp->b_bufobj->bo_object); 490 /* 491 * Don't inherit tbp->b_bufsize as it may be larger due to 492 * a non-page-aligned size. Instead just aggregate using 493 * 'size'. 494 */ 495 if (tbp->b_bcount != size) 496 printf("warning: tbp->b_bcount wrong %ld vs %ld\n", tbp->b_bcount, size); 497 if (tbp->b_bufsize != size) 498 printf("warning: tbp->b_bufsize wrong %ld vs %ld\n", tbp->b_bufsize, size); 499 bp->b_bcount += size; 500 bp->b_bufsize += size; 501 } 502 503 /* 504 * Fully valid pages in the cluster are already good and do not need 505 * to be re-read from disk. Replace the page with bogus_page 506 */ 507 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 508 for (j = 0; j < bp->b_npages; j++) { 509 VM_OBJECT_LOCK_ASSERT(bp->b_pages[j]->object, MA_OWNED); 510 if (bp->b_pages[j]->valid == VM_PAGE_BITS_ALL) 511 bp->b_pages[j] = bogus_page; 512 } 513 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 514 if (bp->b_bufsize > bp->b_kvasize) 515 panic("cluster_rbuild: b_bufsize(%ld) > b_kvasize(%d)\n", 516 bp->b_bufsize, bp->b_kvasize); 517 bp->b_kvasize = bp->b_bufsize; 518 519 if ((bp->b_flags & B_UNMAPPED) == 0) { 520 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 521 (vm_page_t *)bp->b_pages, bp->b_npages); 522 } 523 return (bp); 524 } 525 526 /* 527 * Cleanup after a clustered read or write. 528 * This is complicated by the fact that any of the buffers might have 529 * extra memory (if there were no empty buffer headers at allocbuf time) 530 * that we will need to shift around. 531 */ 532 static void 533 cluster_callback(bp) 534 struct buf *bp; 535 { 536 struct buf *nbp, *tbp; 537 int error = 0; 538 539 /* 540 * Must propogate errors to all the components. 541 */ 542 if (bp->b_ioflags & BIO_ERROR) 543 error = bp->b_error; 544 545 if ((bp->b_flags & B_UNMAPPED) == 0) { 546 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), 547 bp->b_npages); 548 } 549 /* 550 * Move memory from the large cluster buffer into the component 551 * buffers and mark IO as done on these. 552 */ 553 for (tbp = TAILQ_FIRST(&bp->b_cluster.cluster_head); 554 tbp; tbp = nbp) { 555 nbp = TAILQ_NEXT(&tbp->b_cluster, cluster_entry); 556 if (error) { 557 tbp->b_ioflags |= BIO_ERROR; 558 tbp->b_error = error; 559 } else { 560 tbp->b_dirtyoff = tbp->b_dirtyend = 0; 561 tbp->b_flags &= ~B_INVAL; 562 tbp->b_ioflags &= ~BIO_ERROR; 563 /* 564 * XXX the bdwrite()/bqrelse() issued during 565 * cluster building clears B_RELBUF (see bqrelse() 566 * comment). If direct I/O was specified, we have 567 * to restore it here to allow the buffer and VM 568 * to be freed. 569 */ 570 if (tbp->b_flags & B_DIRECT) 571 tbp->b_flags |= B_RELBUF; 572 } 573 bufdone(tbp); 574 } 575 pbrelvp(bp); 576 relpbuf(bp, &cluster_pbuf_freecnt); 577 } 578 579 /* 580 * cluster_wbuild_wb: 581 * 582 * Implement modified write build for cluster. 583 * 584 * write_behind = 0 write behind disabled 585 * write_behind = 1 write behind normal (default) 586 * write_behind = 2 write behind backed-off 587 */ 588 589 static __inline int 590 cluster_wbuild_wb(struct vnode *vp, long size, daddr_t start_lbn, int len, 591 int gbflags) 592 { 593 int r = 0; 594 595 switch (write_behind) { 596 case 2: 597 if (start_lbn < len) 598 break; 599 start_lbn -= len; 600 /* FALLTHROUGH */ 601 case 1: 602 r = cluster_wbuild_gb(vp, size, start_lbn, len, gbflags); 603 /* FALLTHROUGH */ 604 default: 605 /* FALLTHROUGH */ 606 break; 607 } 608 return(r); 609 } 610 611 /* 612 * Do clustered write for FFS. 613 * 614 * Three cases: 615 * 1. Write is not sequential (write asynchronously) 616 * Write is sequential: 617 * 2. beginning of cluster - begin cluster 618 * 3. middle of a cluster - add to cluster 619 * 4. end of a cluster - asynchronously write cluster 620 */ 621 void 622 cluster_write(struct vnode *vp, struct buf *bp, u_quad_t filesize, int seqcount) 623 { 624 625 cluster_write_gb(vp, bp, filesize, seqcount, 0); 626 } 627 628 void 629 cluster_write_gb(struct vnode *vp, struct buf *bp, u_quad_t filesize, 630 int seqcount, int gbflags) 631 { 632 daddr_t lbn; 633 int maxclen, cursize; 634 int lblocksize; 635 int async; 636 637 if (!unmapped_buf_allowed) 638 gbflags &= ~GB_UNMAPPED; 639 640 if (vp->v_type == VREG) { 641 async = DOINGASYNC(vp); 642 lblocksize = vp->v_mount->mnt_stat.f_iosize; 643 } else { 644 async = 0; 645 lblocksize = bp->b_bufsize; 646 } 647 lbn = bp->b_lblkno; 648 KASSERT(bp->b_offset != NOOFFSET, ("cluster_write: no buffer offset")); 649 650 /* Initialize vnode to beginning of file. */ 651 if (lbn == 0) 652 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0; 653 654 if (vp->v_clen == 0 || lbn != vp->v_lastw + 1 || 655 (bp->b_blkno != vp->v_lasta + btodb(lblocksize))) { 656 maxclen = vp->v_mount->mnt_iosize_max / lblocksize - 1; 657 if (vp->v_clen != 0) { 658 /* 659 * Next block is not sequential. 660 * 661 * If we are not writing at end of file, the process 662 * seeked to another point in the file since its last 663 * write, or we have reached our maximum cluster size, 664 * then push the previous cluster. Otherwise try 665 * reallocating to make it sequential. 666 * 667 * Change to algorithm: only push previous cluster if 668 * it was sequential from the point of view of the 669 * seqcount heuristic, otherwise leave the buffer 670 * intact so we can potentially optimize the I/O 671 * later on in the buf_daemon or update daemon 672 * flush. 673 */ 674 cursize = vp->v_lastw - vp->v_cstart + 1; 675 if (((u_quad_t) bp->b_offset + lblocksize) != filesize || 676 lbn != vp->v_lastw + 1 || vp->v_clen <= cursize) { 677 if (!async && seqcount > 0) { 678 cluster_wbuild_wb(vp, lblocksize, 679 vp->v_cstart, cursize, gbflags); 680 } 681 } else { 682 struct buf **bpp, **endbp; 683 struct cluster_save *buflist; 684 685 buflist = cluster_collectbufs(vp, bp, gbflags); 686 endbp = &buflist->bs_children 687 [buflist->bs_nchildren - 1]; 688 if (VOP_REALLOCBLKS(vp, buflist)) { 689 /* 690 * Failed, push the previous cluster 691 * if *really* writing sequentially 692 * in the logical file (seqcount > 1), 693 * otherwise delay it in the hopes that 694 * the low level disk driver can 695 * optimize the write ordering. 696 */ 697 for (bpp = buflist->bs_children; 698 bpp < endbp; bpp++) 699 brelse(*bpp); 700 free(buflist, M_SEGMENT); 701 if (seqcount > 1) { 702 cluster_wbuild_wb(vp, 703 lblocksize, vp->v_cstart, 704 cursize, gbflags); 705 } 706 } else { 707 /* 708 * Succeeded, keep building cluster. 709 */ 710 for (bpp = buflist->bs_children; 711 bpp <= endbp; bpp++) 712 bdwrite(*bpp); 713 free(buflist, M_SEGMENT); 714 vp->v_lastw = lbn; 715 vp->v_lasta = bp->b_blkno; 716 return; 717 } 718 } 719 } 720 /* 721 * Consider beginning a cluster. If at end of file, make 722 * cluster as large as possible, otherwise find size of 723 * existing cluster. 724 */ 725 if ((vp->v_type == VREG) && 726 ((u_quad_t) bp->b_offset + lblocksize) != filesize && 727 (bp->b_blkno == bp->b_lblkno) && 728 (VOP_BMAP(vp, lbn, NULL, &bp->b_blkno, &maxclen, NULL) || 729 bp->b_blkno == -1)) { 730 bawrite(bp); 731 vp->v_clen = 0; 732 vp->v_lasta = bp->b_blkno; 733 vp->v_cstart = lbn + 1; 734 vp->v_lastw = lbn; 735 return; 736 } 737 vp->v_clen = maxclen; 738 if (!async && maxclen == 0) { /* I/O not contiguous */ 739 vp->v_cstart = lbn + 1; 740 bawrite(bp); 741 } else { /* Wait for rest of cluster */ 742 vp->v_cstart = lbn; 743 bdwrite(bp); 744 } 745 } else if (lbn == vp->v_cstart + vp->v_clen) { 746 /* 747 * At end of cluster, write it out if seqcount tells us we 748 * are operating sequentially, otherwise let the buf or 749 * update daemon handle it. 750 */ 751 bdwrite(bp); 752 if (seqcount > 1) { 753 cluster_wbuild_wb(vp, lblocksize, vp->v_cstart, 754 vp->v_clen + 1, gbflags); 755 } 756 vp->v_clen = 0; 757 vp->v_cstart = lbn + 1; 758 } else if (vm_page_count_severe()) { 759 /* 760 * We are low on memory, get it going NOW 761 */ 762 bawrite(bp); 763 } else { 764 /* 765 * In the middle of a cluster, so just delay the I/O for now. 766 */ 767 bdwrite(bp); 768 } 769 vp->v_lastw = lbn; 770 vp->v_lasta = bp->b_blkno; 771 } 772 773 774 /* 775 * This is an awful lot like cluster_rbuild...wish they could be combined. 776 * The last lbn argument is the current block on which I/O is being 777 * performed. Check to see that it doesn't fall in the middle of 778 * the current block (if last_bp == NULL). 779 */ 780 int 781 cluster_wbuild(struct vnode *vp, long size, daddr_t start_lbn, int len) 782 { 783 784 return (cluster_wbuild_gb(vp, size, start_lbn, len, 0)); 785 } 786 787 int 788 cluster_wbuild_gb(struct vnode *vp, long size, daddr_t start_lbn, int len, 789 int gbflags) 790 { 791 struct buf *bp, *tbp; 792 struct bufobj *bo; 793 int i, j; 794 int totalwritten = 0; 795 int dbsize = btodb(size); 796 797 if (!unmapped_buf_allowed) 798 gbflags &= ~GB_UNMAPPED; 799 800 bo = &vp->v_bufobj; 801 while (len > 0) { 802 /* 803 * If the buffer is not delayed-write (i.e. dirty), or it 804 * is delayed-write but either locked or inval, it cannot 805 * partake in the clustered write. 806 */ 807 BO_LOCK(bo); 808 if ((tbp = gbincore(&vp->v_bufobj, start_lbn)) == NULL || 809 (tbp->b_vflags & BV_BKGRDINPROG)) { 810 BO_UNLOCK(bo); 811 ++start_lbn; 812 --len; 813 continue; 814 } 815 if (BUF_LOCK(tbp, 816 LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, BO_MTX(bo))) { 817 ++start_lbn; 818 --len; 819 continue; 820 } 821 if ((tbp->b_flags & (B_INVAL | B_DELWRI)) != B_DELWRI) { 822 BUF_UNLOCK(tbp); 823 ++start_lbn; 824 --len; 825 continue; 826 } 827 if (tbp->b_pin_count > 0) { 828 BUF_UNLOCK(tbp); 829 ++start_lbn; 830 --len; 831 continue; 832 } 833 bremfree(tbp); 834 tbp->b_flags &= ~B_DONE; 835 836 /* 837 * Extra memory in the buffer, punt on this buffer. 838 * XXX we could handle this in most cases, but we would 839 * have to push the extra memory down to after our max 840 * possible cluster size and then potentially pull it back 841 * up if the cluster was terminated prematurely--too much 842 * hassle. 843 */ 844 if (((tbp->b_flags & (B_CLUSTEROK | B_MALLOC | B_VMIO)) != 845 (B_CLUSTEROK | B_VMIO)) || 846 (tbp->b_bcount != tbp->b_bufsize) || 847 (tbp->b_bcount != size) || 848 (len == 1) || 849 ((bp = getpbuf(&cluster_pbuf_freecnt)) == NULL)) { 850 totalwritten += tbp->b_bufsize; 851 bawrite(tbp); 852 ++start_lbn; 853 --len; 854 continue; 855 } 856 857 /* 858 * We got a pbuf to make the cluster in. 859 * so initialise it. 860 */ 861 TAILQ_INIT(&bp->b_cluster.cluster_head); 862 bp->b_bcount = 0; 863 bp->b_bufsize = 0; 864 bp->b_npages = 0; 865 if (tbp->b_wcred != NOCRED) 866 bp->b_wcred = crhold(tbp->b_wcred); 867 868 bp->b_blkno = tbp->b_blkno; 869 bp->b_lblkno = tbp->b_lblkno; 870 bp->b_offset = tbp->b_offset; 871 872 /* 873 * We are synthesizing a buffer out of vm_page_t's, but 874 * if the block size is not page aligned then the starting 875 * address may not be either. Inherit the b_data offset 876 * from the original buffer. 877 */ 878 if ((gbflags & GB_UNMAPPED) == 0 || 879 (tbp->b_flags & B_VMIO) == 0) { 880 bp->b_data = (char *)((vm_offset_t)bp->b_data | 881 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 882 } else { 883 bp->b_flags |= B_UNMAPPED; 884 bp->b_data = unmapped_buf; 885 } 886 bp->b_flags |= B_CLUSTER | (tbp->b_flags & (B_VMIO | 887 B_NEEDCOMMIT)); 888 bp->b_iodone = cluster_callback; 889 pbgetvp(vp, bp); 890 /* 891 * From this location in the file, scan forward to see 892 * if there are buffers with adjacent data that need to 893 * be written as well. 894 */ 895 for (i = 0; i < len; ++i, ++start_lbn) { 896 if (i != 0) { /* If not the first buffer */ 897 /* 898 * If the adjacent data is not even in core it 899 * can't need to be written. 900 */ 901 BO_LOCK(bo); 902 if ((tbp = gbincore(bo, start_lbn)) == NULL || 903 (tbp->b_vflags & BV_BKGRDINPROG)) { 904 BO_UNLOCK(bo); 905 break; 906 } 907 908 /* 909 * If it IS in core, but has different 910 * characteristics, or is locked (which 911 * means it could be undergoing a background 912 * I/O or be in a weird state), then don't 913 * cluster with it. 914 */ 915 if (BUF_LOCK(tbp, 916 LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, 917 BO_MTX(bo))) 918 break; 919 920 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK | 921 B_INVAL | B_DELWRI | B_NEEDCOMMIT)) 922 != (B_DELWRI | B_CLUSTEROK | 923 (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) || 924 tbp->b_wcred != bp->b_wcred) { 925 BUF_UNLOCK(tbp); 926 break; 927 } 928 929 /* 930 * Check that the combined cluster 931 * would make sense with regard to pages 932 * and would not be too large 933 */ 934 if ((tbp->b_bcount != size) || 935 ((bp->b_blkno + (dbsize * i)) != 936 tbp->b_blkno) || 937 ((tbp->b_npages + bp->b_npages) > 938 (vp->v_mount->mnt_iosize_max / PAGE_SIZE))) { 939 BUF_UNLOCK(tbp); 940 break; 941 } 942 943 /* 944 * Do not pull in pinned buffers. 945 */ 946 if (tbp->b_pin_count > 0) { 947 BUF_UNLOCK(tbp); 948 break; 949 } 950 951 /* 952 * Ok, it's passed all the tests, 953 * so remove it from the free list 954 * and mark it busy. We will use it. 955 */ 956 bremfree(tbp); 957 tbp->b_flags &= ~B_DONE; 958 } /* end of code for non-first buffers only */ 959 /* 960 * If the IO is via the VM then we do some 961 * special VM hackery (yuck). Since the buffer's 962 * block size may not be page-aligned it is possible 963 * for a page to be shared between two buffers. We 964 * have to get rid of the duplication when building 965 * the cluster. 966 */ 967 if (tbp->b_flags & B_VMIO) { 968 vm_page_t m; 969 970 VM_OBJECT_LOCK(tbp->b_bufobj->bo_object); 971 if (i != 0) { /* if not first buffer */ 972 for (j = 0; j < tbp->b_npages; j += 1) { 973 m = tbp->b_pages[j]; 974 if (m->oflags & VPO_BUSY) { 975 VM_OBJECT_UNLOCK( 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_io_start(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_UNLOCK(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 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head, 1011 tbp, b_cluster.cluster_entry); 1012 } 1013 finishcluster: 1014 if ((bp->b_flags & B_UNMAPPED) == 0) { 1015 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 1016 (vm_page_t *)bp->b_pages, bp->b_npages); 1017 } 1018 if (bp->b_bufsize > bp->b_kvasize) 1019 panic( 1020 "cluster_wbuild: b_bufsize(%ld) > b_kvasize(%d)\n", 1021 bp->b_bufsize, bp->b_kvasize); 1022 bp->b_kvasize = bp->b_bufsize; 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 }
Cache object: dba8949420afc3f73d8ddefc4a2a9233
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