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("$FreeBSD$"); 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 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 curthread->td_ru.ru_inblock++; 245 } 246 247 /* 248 * If we have been doing sequential I/O, then do some read-ahead. 249 */ 250 while (lblkno < (origblkno + maxra)) { 251 error = VOP_BMAP(vp, lblkno, NULL, &blkno, &ncontig, NULL); 252 if (error) 253 break; 254 255 if (blkno == -1) 256 break; 257 258 /* 259 * We could throttle ncontig here by maxra but we might as 260 * well read the data if it is contiguous. We're throttled 261 * by racluster anyway. 262 */ 263 if (ncontig) { 264 ncontig = min(ncontig + 1, racluster); 265 rbp = cluster_rbuild(vp, filesize, lblkno, blkno, 266 size, ncontig, gbflags, NULL); 267 lblkno += (rbp->b_bufsize / size); 268 if (rbp->b_flags & B_DELWRI) { 269 bqrelse(rbp); 270 continue; 271 } 272 } else { 273 rbp = getblk(vp, lblkno, size, 0, 0, gbflags); 274 lblkno += 1; 275 if (rbp->b_flags & B_DELWRI) { 276 bqrelse(rbp); 277 continue; 278 } 279 rbp->b_flags |= B_ASYNC | B_RAM; 280 rbp->b_iocmd = BIO_READ; 281 rbp->b_blkno = blkno; 282 } 283 if (rbp->b_flags & B_CACHE) { 284 rbp->b_flags &= ~B_ASYNC; 285 bqrelse(rbp); 286 continue; 287 } 288 if ((rbp->b_flags & B_CLUSTER) == 0) { 289 vfs_busy_pages(rbp, 0); 290 } 291 rbp->b_flags &= ~B_INVAL; 292 rbp->b_ioflags &= ~BIO_ERROR; 293 if ((rbp->b_flags & B_ASYNC) || rbp->b_iodone != NULL) 294 BUF_KERNPROC(rbp); 295 rbp->b_iooffset = dbtob(rbp->b_blkno); 296 bstrategy(rbp); 297 curthread->td_ru.ru_inblock++; 298 } 299 300 if (reqbp) { 301 /* 302 * Like bread, always brelse() the buffer when 303 * returning an error. 304 */ 305 error = bufwait(reqbp); 306 if (error != 0) { 307 brelse(reqbp); 308 *bpp = NULL; 309 } 310 } 311 return (error); 312 } 313 314 /* 315 * If blocks are contiguous on disk, use this to provide clustered 316 * read ahead. We will read as many blocks as possible sequentially 317 * and then parcel them up into logical blocks in the buffer hash table. 318 */ 319 static struct buf * 320 cluster_rbuild(struct vnode *vp, u_quad_t filesize, daddr_t lbn, 321 daddr_t blkno, long size, int run, int gbflags, struct buf *fbp) 322 { 323 struct buf *bp, *tbp; 324 daddr_t bn; 325 off_t off; 326 long tinc, tsize; 327 int i, inc, j, k, toff; 328 329 KASSERT(size == vp->v_mount->mnt_stat.f_iosize, 330 ("cluster_rbuild: size %ld != f_iosize %jd\n", 331 size, (intmax_t)vp->v_mount->mnt_stat.f_iosize)); 332 333 /* 334 * avoid a division 335 */ 336 while ((u_quad_t) size * (lbn + run) > filesize) { 337 --run; 338 } 339 340 if (fbp) { 341 tbp = fbp; 342 tbp->b_iocmd = BIO_READ; 343 } else { 344 tbp = getblk(vp, lbn, size, 0, 0, gbflags); 345 if (tbp->b_flags & B_CACHE) 346 return tbp; 347 tbp->b_flags |= B_ASYNC | B_RAM; 348 tbp->b_iocmd = BIO_READ; 349 } 350 tbp->b_blkno = blkno; 351 if( (tbp->b_flags & B_MALLOC) || 352 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1) ) 353 return tbp; 354 355 bp = trypbuf(&cluster_pbuf_freecnt); 356 if (bp == 0) 357 return tbp; 358 359 /* 360 * We are synthesizing a buffer out of vm_page_t's, but 361 * if the block size is not page aligned then the starting 362 * address may not be either. Inherit the b_data offset 363 * from the original buffer. 364 */ 365 bp->b_flags = B_ASYNC | B_CLUSTER | B_VMIO; 366 if ((gbflags & GB_UNMAPPED) != 0) { 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 for (bn = blkno, i = 0; i < run; ++i, bn += inc) { 388 if (i == 0) { 389 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object); 390 vfs_drain_busy_pages(tbp); 391 vm_object_pip_add(tbp->b_bufobj->bo_object, 392 tbp->b_npages); 393 for (k = 0; k < tbp->b_npages; k++) 394 vm_page_sbusy(tbp->b_pages[k]); 395 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object); 396 } else { 397 if ((bp->b_npages * PAGE_SIZE) + 398 round_page(size) > vp->v_mount->mnt_iosize_max) { 399 break; 400 } 401 402 tbp = getblk(vp, lbn + i, size, 0, 0, GB_LOCK_NOWAIT | 403 (gbflags & GB_UNMAPPED)); 404 405 /* Don't wait around for locked bufs. */ 406 if (tbp == NULL) 407 break; 408 409 /* 410 * Stop scanning if the buffer is fully valid 411 * (marked B_CACHE), or locked (may be doing a 412 * background write), or if the buffer is not 413 * VMIO backed. The clustering code can only deal 414 * with VMIO-backed buffers. The bo lock is not 415 * required for the BKGRDINPROG check since it 416 * can not be set without the buf lock. 417 */ 418 if ((tbp->b_vflags & BV_BKGRDINPROG) || 419 (tbp->b_flags & B_CACHE) || 420 (tbp->b_flags & B_VMIO) == 0) { 421 bqrelse(tbp); 422 break; 423 } 424 425 /* 426 * The buffer must be completely invalid in order to 427 * take part in the cluster. If it is partially valid 428 * then we stop. 429 */ 430 off = tbp->b_offset; 431 tsize = size; 432 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object); 433 for (j = 0; tsize > 0; j++) { 434 toff = off & PAGE_MASK; 435 tinc = tsize; 436 if (toff + tinc > PAGE_SIZE) 437 tinc = PAGE_SIZE - toff; 438 VM_OBJECT_ASSERT_WLOCKED(tbp->b_pages[j]->object); 439 if ((tbp->b_pages[j]->valid & 440 vm_page_bits(toff, tinc)) != 0) 441 break; 442 if (vm_page_xbusied(tbp->b_pages[j])) 443 break; 444 vm_object_pip_add(tbp->b_bufobj->bo_object, 1); 445 vm_page_sbusy(tbp->b_pages[j]); 446 off += tinc; 447 tsize -= tinc; 448 } 449 if (tsize > 0) { 450 clean_sbusy: 451 vm_object_pip_add(tbp->b_bufobj->bo_object, -j); 452 for (k = 0; k < j; k++) 453 vm_page_sunbusy(tbp->b_pages[k]); 454 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object); 455 bqrelse(tbp); 456 break; 457 } 458 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object); 459 460 /* 461 * Set a read-ahead mark as appropriate 462 */ 463 if ((fbp && (i == 1)) || (i == (run - 1))) 464 tbp->b_flags |= B_RAM; 465 466 /* 467 * Set the buffer up for an async read (XXX should 468 * we do this only if we do not wind up brelse()ing?). 469 * Set the block number if it isn't set, otherwise 470 * if it is make sure it matches the block number we 471 * expect. 472 */ 473 tbp->b_flags |= B_ASYNC; 474 tbp->b_iocmd = BIO_READ; 475 if (tbp->b_blkno == tbp->b_lblkno) { 476 tbp->b_blkno = bn; 477 } else if (tbp->b_blkno != bn) { 478 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object); 479 goto clean_sbusy; 480 } 481 } 482 /* 483 * XXX fbp from caller may not be B_ASYNC, but we are going 484 * to biodone() it in cluster_callback() anyway 485 */ 486 BUF_KERNPROC(tbp); 487 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head, 488 tbp, b_cluster.cluster_entry); 489 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object); 490 for (j = 0; j < tbp->b_npages; j += 1) { 491 vm_page_t m; 492 m = tbp->b_pages[j]; 493 if ((bp->b_npages == 0) || 494 (bp->b_pages[bp->b_npages-1] != m)) { 495 bp->b_pages[bp->b_npages] = m; 496 bp->b_npages++; 497 } 498 if (m->valid == VM_PAGE_BITS_ALL) 499 tbp->b_pages[j] = bogus_page; 500 } 501 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object); 502 /* 503 * Don't inherit tbp->b_bufsize as it may be larger due to 504 * a non-page-aligned size. Instead just aggregate using 505 * 'size'. 506 */ 507 if (tbp->b_bcount != size) 508 printf("warning: tbp->b_bcount wrong %ld vs %ld\n", tbp->b_bcount, size); 509 if (tbp->b_bufsize != size) 510 printf("warning: tbp->b_bufsize wrong %ld vs %ld\n", tbp->b_bufsize, size); 511 bp->b_bcount += size; 512 bp->b_bufsize += size; 513 } 514 515 /* 516 * Fully valid pages in the cluster are already good and do not need 517 * to be re-read from disk. Replace the page with bogus_page 518 */ 519 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 520 for (j = 0; j < bp->b_npages; j++) { 521 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[j]->object); 522 if (bp->b_pages[j]->valid == VM_PAGE_BITS_ALL) 523 bp->b_pages[j] = bogus_page; 524 } 525 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 526 if (bp->b_bufsize > bp->b_kvasize) 527 panic("cluster_rbuild: b_bufsize(%ld) > b_kvasize(%d)\n", 528 bp->b_bufsize, bp->b_kvasize); 529 530 if (buf_mapped(bp)) { 531 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 532 (vm_page_t *)bp->b_pages, bp->b_npages); 533 } 534 return (bp); 535 } 536 537 /* 538 * Cleanup after a clustered read or write. 539 * This is complicated by the fact that any of the buffers might have 540 * extra memory (if there were no empty buffer headers at allocbuf time) 541 * that we will need to shift around. 542 */ 543 static void 544 cluster_callback(bp) 545 struct buf *bp; 546 { 547 struct buf *nbp, *tbp; 548 int error = 0; 549 550 /* 551 * Must propogate errors to all the components. 552 */ 553 if (bp->b_ioflags & BIO_ERROR) 554 error = bp->b_error; 555 556 if (buf_mapped(bp)) { 557 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), 558 bp->b_npages); 559 } 560 /* 561 * Move memory from the large cluster buffer into the component 562 * buffers and mark IO as done on these. 563 */ 564 for (tbp = TAILQ_FIRST(&bp->b_cluster.cluster_head); 565 tbp; tbp = nbp) { 566 nbp = TAILQ_NEXT(&tbp->b_cluster, cluster_entry); 567 if (error) { 568 tbp->b_ioflags |= BIO_ERROR; 569 tbp->b_error = error; 570 } else { 571 tbp->b_dirtyoff = tbp->b_dirtyend = 0; 572 tbp->b_flags &= ~B_INVAL; 573 tbp->b_ioflags &= ~BIO_ERROR; 574 /* 575 * XXX the bdwrite()/bqrelse() issued during 576 * cluster building clears B_RELBUF (see bqrelse() 577 * comment). If direct I/O was specified, we have 578 * to restore it here to allow the buffer and VM 579 * to be freed. 580 */ 581 if (tbp->b_flags & B_DIRECT) 582 tbp->b_flags |= B_RELBUF; 583 } 584 bufdone(tbp); 585 } 586 pbrelvp(bp); 587 relpbuf(bp, &cluster_pbuf_freecnt); 588 } 589 590 /* 591 * cluster_wbuild_wb: 592 * 593 * Implement modified write build for cluster. 594 * 595 * write_behind = 0 write behind disabled 596 * write_behind = 1 write behind normal (default) 597 * write_behind = 2 write behind backed-off 598 */ 599 600 static __inline int 601 cluster_wbuild_wb(struct vnode *vp, long size, daddr_t start_lbn, int len, 602 int gbflags) 603 { 604 int r = 0; 605 606 switch (write_behind) { 607 case 2: 608 if (start_lbn < len) 609 break; 610 start_lbn -= len; 611 /* FALLTHROUGH */ 612 case 1: 613 r = cluster_wbuild(vp, size, start_lbn, len, gbflags); 614 /* FALLTHROUGH */ 615 default: 616 /* FALLTHROUGH */ 617 break; 618 } 619 return(r); 620 } 621 622 /* 623 * Do clustered write for FFS. 624 * 625 * Three cases: 626 * 1. Write is not sequential (write asynchronously) 627 * Write is sequential: 628 * 2. beginning of cluster - begin cluster 629 * 3. middle of a cluster - add to cluster 630 * 4. end of a cluster - asynchronously write cluster 631 */ 632 void 633 cluster_write(struct vnode *vp, struct buf *bp, u_quad_t filesize, int seqcount, 634 int gbflags) 635 { 636 daddr_t lbn; 637 int maxclen, cursize; 638 int lblocksize; 639 int async; 640 641 if (!unmapped_buf_allowed) 642 gbflags &= ~GB_UNMAPPED; 643 644 if (vp->v_type == VREG) { 645 async = DOINGASYNC(vp); 646 lblocksize = vp->v_mount->mnt_stat.f_iosize; 647 } else { 648 async = 0; 649 lblocksize = bp->b_bufsize; 650 } 651 lbn = bp->b_lblkno; 652 KASSERT(bp->b_offset != NOOFFSET, ("cluster_write: no buffer offset")); 653 654 /* Initialize vnode to beginning of file. */ 655 if (lbn == 0) 656 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0; 657 658 if (vp->v_clen == 0 || lbn != vp->v_lastw + 1 || 659 (bp->b_blkno != vp->v_lasta + btodb(lblocksize))) { 660 maxclen = vp->v_mount->mnt_iosize_max / lblocksize - 1; 661 if (vp->v_clen != 0) { 662 /* 663 * Next block is not sequential. 664 * 665 * If we are not writing at end of file, the process 666 * seeked to another point in the file since its last 667 * write, or we have reached our maximum cluster size, 668 * then push the previous cluster. Otherwise try 669 * reallocating to make it sequential. 670 * 671 * Change to algorithm: only push previous cluster if 672 * it was sequential from the point of view of the 673 * seqcount heuristic, otherwise leave the buffer 674 * intact so we can potentially optimize the I/O 675 * later on in the buf_daemon or update daemon 676 * flush. 677 */ 678 cursize = vp->v_lastw - vp->v_cstart + 1; 679 if (((u_quad_t) bp->b_offset + lblocksize) != filesize || 680 lbn != vp->v_lastw + 1 || vp->v_clen <= cursize) { 681 if (!async && seqcount > 0) { 682 cluster_wbuild_wb(vp, lblocksize, 683 vp->v_cstart, cursize, gbflags); 684 } 685 } else { 686 struct buf **bpp, **endbp; 687 struct cluster_save *buflist; 688 689 buflist = cluster_collectbufs(vp, bp, gbflags); 690 endbp = &buflist->bs_children 691 [buflist->bs_nchildren - 1]; 692 if (VOP_REALLOCBLKS(vp, buflist)) { 693 /* 694 * Failed, push the previous cluster 695 * if *really* writing sequentially 696 * in the logical file (seqcount > 1), 697 * otherwise delay it in the hopes that 698 * the low level disk driver can 699 * optimize the write ordering. 700 */ 701 for (bpp = buflist->bs_children; 702 bpp < endbp; bpp++) 703 brelse(*bpp); 704 free(buflist, M_SEGMENT); 705 if (seqcount > 1) { 706 cluster_wbuild_wb(vp, 707 lblocksize, vp->v_cstart, 708 cursize, gbflags); 709 } 710 } else { 711 /* 712 * Succeeded, keep building cluster. 713 */ 714 for (bpp = buflist->bs_children; 715 bpp <= endbp; bpp++) 716 bdwrite(*bpp); 717 free(buflist, M_SEGMENT); 718 vp->v_lastw = lbn; 719 vp->v_lasta = bp->b_blkno; 720 return; 721 } 722 } 723 } 724 /* 725 * Consider beginning a cluster. If at end of file, make 726 * cluster as large as possible, otherwise find size of 727 * existing cluster. 728 */ 729 if ((vp->v_type == VREG) && 730 ((u_quad_t) bp->b_offset + lblocksize) != filesize && 731 (bp->b_blkno == bp->b_lblkno) && 732 (VOP_BMAP(vp, lbn, NULL, &bp->b_blkno, &maxclen, NULL) || 733 bp->b_blkno == -1)) { 734 bawrite(bp); 735 vp->v_clen = 0; 736 vp->v_lasta = bp->b_blkno; 737 vp->v_cstart = lbn + 1; 738 vp->v_lastw = lbn; 739 return; 740 } 741 vp->v_clen = maxclen; 742 if (!async && maxclen == 0) { /* I/O not contiguous */ 743 vp->v_cstart = lbn + 1; 744 bawrite(bp); 745 } else { /* Wait for rest of cluster */ 746 vp->v_cstart = lbn; 747 bdwrite(bp); 748 } 749 } else if (lbn == vp->v_cstart + vp->v_clen) { 750 /* 751 * At end of cluster, write it out if seqcount tells us we 752 * are operating sequentially, otherwise let the buf or 753 * update daemon handle it. 754 */ 755 bdwrite(bp); 756 if (seqcount > 1) { 757 cluster_wbuild_wb(vp, lblocksize, vp->v_cstart, 758 vp->v_clen + 1, gbflags); 759 } 760 vp->v_clen = 0; 761 vp->v_cstart = lbn + 1; 762 } else if (vm_page_count_severe()) { 763 /* 764 * We are low on memory, get it going NOW 765 */ 766 bawrite(bp); 767 } else { 768 /* 769 * In the middle of a cluster, so just delay the I/O for now. 770 */ 771 bdwrite(bp); 772 } 773 vp->v_lastw = lbn; 774 vp->v_lasta = bp->b_blkno; 775 } 776 777 778 /* 779 * This is an awful lot like cluster_rbuild...wish they could be combined. 780 * The last lbn argument is the current block on which I/O is being 781 * performed. Check to see that it doesn't fall in the middle of 782 * the current block (if last_bp == NULL). 783 */ 784 int 785 cluster_wbuild(struct vnode *vp, long size, daddr_t start_lbn, int len, 786 int gbflags) 787 { 788 struct buf *bp, *tbp; 789 struct bufobj *bo; 790 int i, j; 791 int totalwritten = 0; 792 int dbsize = btodb(size); 793 794 if (!unmapped_buf_allowed) 795 gbflags &= ~GB_UNMAPPED; 796 797 bo = &vp->v_bufobj; 798 while (len > 0) { 799 /* 800 * If the buffer is not delayed-write (i.e. dirty), or it 801 * is delayed-write but either locked or inval, it cannot 802 * partake in the clustered write. 803 */ 804 BO_LOCK(bo); 805 if ((tbp = gbincore(&vp->v_bufobj, start_lbn)) == NULL || 806 (tbp->b_vflags & BV_BKGRDINPROG)) { 807 BO_UNLOCK(bo); 808 ++start_lbn; 809 --len; 810 continue; 811 } 812 if (BUF_LOCK(tbp, 813 LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, BO_LOCKPTR(bo))) { 814 ++start_lbn; 815 --len; 816 continue; 817 } 818 if ((tbp->b_flags & (B_INVAL | B_DELWRI)) != B_DELWRI) { 819 BUF_UNLOCK(tbp); 820 ++start_lbn; 821 --len; 822 continue; 823 } 824 if (tbp->b_pin_count > 0) { 825 BUF_UNLOCK(tbp); 826 ++start_lbn; 827 --len; 828 continue; 829 } 830 bremfree(tbp); 831 tbp->b_flags &= ~B_DONE; 832 833 /* 834 * Extra memory in the buffer, punt on this buffer. 835 * XXX we could handle this in most cases, but we would 836 * have to push the extra memory down to after our max 837 * possible cluster size and then potentially pull it back 838 * up if the cluster was terminated prematurely--too much 839 * hassle. 840 */ 841 if (((tbp->b_flags & (B_CLUSTEROK | B_MALLOC | B_VMIO)) != 842 (B_CLUSTEROK | B_VMIO)) || 843 (tbp->b_bcount != tbp->b_bufsize) || 844 (tbp->b_bcount != size) || 845 (len == 1) || 846 ((bp = (vp->v_vflag & VV_MD) != 0 ? 847 trypbuf(&cluster_pbuf_freecnt) : 848 getpbuf(&cluster_pbuf_freecnt)) == NULL)) { 849 totalwritten += tbp->b_bufsize; 850 bawrite(tbp); 851 ++start_lbn; 852 --len; 853 continue; 854 } 855 856 /* 857 * We got a pbuf to make the cluster in. 858 * so initialise it. 859 */ 860 TAILQ_INIT(&bp->b_cluster.cluster_head); 861 bp->b_bcount = 0; 862 bp->b_bufsize = 0; 863 bp->b_npages = 0; 864 if (tbp->b_wcred != NOCRED) 865 bp->b_wcred = crhold(tbp->b_wcred); 866 867 bp->b_blkno = tbp->b_blkno; 868 bp->b_lblkno = tbp->b_lblkno; 869 bp->b_offset = tbp->b_offset; 870 871 /* 872 * We are synthesizing a buffer out of vm_page_t's, but 873 * if the block size is not page aligned then the starting 874 * address may not be either. Inherit the b_data offset 875 * from the original buffer. 876 */ 877 if ((gbflags & GB_UNMAPPED) == 0 || 878 (tbp->b_flags & B_VMIO) == 0) { 879 bp->b_data = (char *)((vm_offset_t)bp->b_data | 880 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 881 } else { 882 bp->b_data = unmapped_buf; 883 } 884 bp->b_flags |= B_CLUSTER | (tbp->b_flags & (B_VMIO | 885 B_NEEDCOMMIT)); 886 bp->b_iodone = cluster_callback; 887 pbgetvp(vp, bp); 888 /* 889 * From this location in the file, scan forward to see 890 * if there are buffers with adjacent data that need to 891 * be written as well. 892 */ 893 for (i = 0; i < len; ++i, ++start_lbn) { 894 if (i != 0) { /* If not the first buffer */ 895 /* 896 * If the adjacent data is not even in core it 897 * can't need to be written. 898 */ 899 BO_LOCK(bo); 900 if ((tbp = gbincore(bo, start_lbn)) == NULL || 901 (tbp->b_vflags & BV_BKGRDINPROG)) { 902 BO_UNLOCK(bo); 903 break; 904 } 905 906 /* 907 * If it IS in core, but has different 908 * characteristics, or is locked (which 909 * means it could be undergoing a background 910 * I/O or be in a weird state), then don't 911 * cluster with it. 912 */ 913 if (BUF_LOCK(tbp, 914 LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, 915 BO_LOCKPTR(bo))) 916 break; 917 918 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK | 919 B_INVAL | B_DELWRI | B_NEEDCOMMIT)) 920 != (B_DELWRI | B_CLUSTEROK | 921 (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) || 922 tbp->b_wcred != bp->b_wcred) { 923 BUF_UNLOCK(tbp); 924 break; 925 } 926 927 /* 928 * Check that the combined cluster 929 * would make sense with regard to pages 930 * and would not be too large 931 */ 932 if ((tbp->b_bcount != size) || 933 ((bp->b_blkno + (dbsize * i)) != 934 tbp->b_blkno) || 935 ((tbp->b_npages + bp->b_npages) > 936 (vp->v_mount->mnt_iosize_max / PAGE_SIZE))) { 937 BUF_UNLOCK(tbp); 938 break; 939 } 940 941 /* 942 * Do not pull in pinned buffers. 943 */ 944 if (tbp->b_pin_count > 0) { 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 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head, 1011 tbp, b_cluster.cluster_entry); 1012 } 1013 finishcluster: 1014 if (buf_mapped(bp)) { 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 totalwritten += bp->b_bufsize; 1023 bp->b_dirtyoff = 0; 1024 bp->b_dirtyend = bp->b_bufsize; 1025 bawrite(bp); 1026 1027 len -= i; 1028 } 1029 return totalwritten; 1030 } 1031 1032 /* 1033 * Collect together all the buffers in a cluster. 1034 * Plus add one additional buffer. 1035 */ 1036 static struct cluster_save * 1037 cluster_collectbufs(struct vnode *vp, struct buf *last_bp, int gbflags) 1038 { 1039 struct cluster_save *buflist; 1040 struct buf *bp; 1041 daddr_t lbn; 1042 int i, len; 1043 1044 len = vp->v_lastw - vp->v_cstart + 1; 1045 buflist = malloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist), 1046 M_SEGMENT, M_WAITOK); 1047 buflist->bs_nchildren = 0; 1048 buflist->bs_children = (struct buf **) (buflist + 1); 1049 for (lbn = vp->v_cstart, i = 0; i < len; lbn++, i++) { 1050 (void)bread_gb(vp, lbn, last_bp->b_bcount, NOCRED, 1051 gbflags, &bp); 1052 buflist->bs_children[i] = bp; 1053 if (bp->b_blkno == bp->b_lblkno) 1054 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, 1055 NULL, NULL); 1056 } 1057 buflist->bs_children[i] = bp = last_bp; 1058 if (bp->b_blkno == bp->b_lblkno) 1059 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 1060 buflist->bs_nchildren = i + 1; 1061 return (buflist); 1062 } 1063