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. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgement: 17 * This product includes software developed by the University of 18 * California, Berkeley and its contributors. 19 * 4. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 * 35 * @(#)vfs_cluster.c 8.7 (Berkeley) 2/13/94 36 * $FreeBSD: src/sys/kern/vfs_cluster.c,v 1.92.2.9 2001/11/18 07:10:59 dillon Exp $ 37 * $DragonFly: src/sys/kern/vfs_cluster.c,v 1.40 2008/07/14 03:09:00 dillon Exp $ 38 */ 39 40 #include "opt_debug_cluster.h" 41 42 #include <sys/param.h> 43 #include <sys/systm.h> 44 #include <sys/kernel.h> 45 #include <sys/proc.h> 46 #include <sys/buf.h> 47 #include <sys/vnode.h> 48 #include <sys/malloc.h> 49 #include <sys/mount.h> 50 #include <sys/resourcevar.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 #include <sys/buf2.h> 57 #include <vm/vm_page2.h> 58 59 #if defined(CLUSTERDEBUG) 60 #include <sys/sysctl.h> 61 static int rcluster= 0; 62 SYSCTL_INT(_debug, OID_AUTO, rcluster, CTLFLAG_RW, &rcluster, 0, ""); 63 #endif 64 65 static MALLOC_DEFINE(M_SEGMENT, "cluster_save", "cluster_save buffer"); 66 67 static struct cluster_save * 68 cluster_collectbufs (struct vnode *vp, struct buf *last_bp, 69 int blksize); 70 static struct buf * 71 cluster_rbuild (struct vnode *vp, off_t filesize, off_t loffset, 72 off_t doffset, int blksize, int run, 73 struct buf *fbp, int doasync); 74 static void cluster_callback (struct bio *); 75 76 77 static int write_behind = 1; 78 SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0, ""); 79 80 extern vm_page_t bogus_page; 81 82 extern int cluster_pbuf_freecnt; 83 84 /* 85 * Maximum number of blocks for read-ahead. 86 */ 87 #define MAXRA 32 88 89 /* 90 * This replaces bread. 91 */ 92 int 93 cluster_read(struct vnode *vp, off_t filesize, off_t loffset, 94 int blksize, int totread, int seqcount, struct buf **bpp) 95 { 96 struct buf *bp, *rbp, *reqbp; 97 off_t origoffset; 98 off_t doffset; 99 int error; 100 int i; 101 int maxra, racluster; 102 103 error = 0; 104 105 /* 106 * Try to limit the amount of read-ahead by a few 107 * ad-hoc parameters. This needs work!!! 108 */ 109 racluster = vmaxiosize(vp) / blksize; 110 maxra = 2 * racluster + (totread / blksize); 111 if (maxra > MAXRA) 112 maxra = MAXRA; 113 if (maxra > nbuf/8) 114 maxra = nbuf/8; 115 116 /* 117 * get the requested block 118 */ 119 *bpp = reqbp = bp = getblk(vp, loffset, blksize, 0, 0); 120 origoffset = loffset; 121 122 /* 123 * if it is in the cache, then check to see if the reads have been 124 * sequential. If they have, then try some read-ahead, otherwise 125 * back-off on prospective read-aheads. 126 */ 127 if (bp->b_flags & B_CACHE) { 128 if (!seqcount) { 129 return 0; 130 } else if ((bp->b_flags & B_RAM) == 0) { 131 return 0; 132 } else { 133 struct buf *tbp; 134 bp->b_flags &= ~B_RAM; 135 136 /* 137 * Set read-ahead-mark only if we can passively lock 138 * the buffer. Note that with these flags the bp 139 * could very exist even though NULL is returned. 140 */ 141 for (i = 1; i < maxra; i++) { 142 tbp = findblk(vp, loffset + i * blksize, 143 FINDBLK_NBLOCK); 144 if (tbp == NULL) 145 break; 146 if (((i % racluster) == (racluster - 1)) || 147 (i == (maxra - 1))) { 148 tbp->b_flags |= B_RAM; 149 } 150 BUF_UNLOCK(tbp); 151 } 152 if (i >= maxra) 153 return 0; 154 loffset += i * blksize; 155 } 156 reqbp = bp = NULL; 157 } else { 158 off_t firstread = bp->b_loffset; 159 int nblks; 160 161 KASSERT(firstread != NOOFFSET, 162 ("cluster_read: no buffer offset")); 163 if (firstread + totread > filesize) 164 totread = (int)(filesize - firstread); 165 nblks = totread / blksize; 166 if (nblks) { 167 int burstbytes; 168 169 if (nblks > racluster) 170 nblks = racluster; 171 172 error = VOP_BMAP(vp, loffset, &doffset, 173 &burstbytes, NULL, BUF_CMD_READ); 174 if (error) 175 goto single_block_read; 176 if (doffset == NOOFFSET) 177 goto single_block_read; 178 if (burstbytes < blksize * 2) 179 goto single_block_read; 180 if (nblks > burstbytes / blksize) 181 nblks = burstbytes / blksize; 182 183 bp = cluster_rbuild(vp, filesize, loffset, 184 doffset, blksize, nblks, bp, 0); 185 loffset += bp->b_bufsize; 186 } else { 187 single_block_read: 188 /* 189 * if it isn't in the cache, then get a chunk from 190 * disk if sequential, otherwise just get the block. 191 */ 192 bp->b_flags |= B_RAM; 193 loffset += blksize; 194 } 195 } 196 197 /* 198 * Handle the synchronous read. This only occurs if B_CACHE was 199 * not set. bp (and rbp) could be either a cluster bp or a normal 200 * bp depending on the what cluster_rbuild() decided to do. If 201 * it is a cluster bp, vfs_busy_pages() has already been called. 202 */ 203 if (bp) { 204 #if defined(CLUSTERDEBUG) 205 if (rcluster) 206 kprintf("S(%lld,%d,%d) ", 207 bp->b_loffset, bp->b_bcount, seqcount); 208 #endif 209 bp->b_cmd = BUF_CMD_READ; 210 if ((bp->b_flags & B_CLUSTER) == 0) 211 vfs_busy_pages(vp, bp); 212 bp->b_flags &= ~(B_ERROR|B_INVAL); 213 if ((bp->b_flags & B_ASYNC) || bp->b_bio1.bio_done != NULL) 214 BUF_KERNPROC(bp); 215 vn_strategy(vp, &bp->b_bio1); 216 if (bp->b_flags & B_ERROR) { 217 if ((error = bp->b_error) == 0) 218 error = EIO; 219 } else { 220 error = 0; 221 } 222 } 223 224 /* 225 * If we have been doing sequential I/O, then do some read-ahead. 226 * 227 * Only mess with buffers which we can immediately lock. HAMMER 228 * will do device-readahead irrespective of what the blocks 229 * represent. 230 */ 231 rbp = NULL; 232 if (!error && 233 seqcount && 234 loffset < origoffset + seqcount * blksize && 235 loffset + blksize <= filesize 236 ) { 237 int nblksread; 238 int ntoread; 239 int burstbytes; 240 int tmp_error; 241 242 rbp = getblk(vp, loffset, blksize, 243 GETBLK_SZMATCH|GETBLK_NOWAIT, 0); 244 if (rbp == NULL) 245 goto no_read_ahead; 246 if ((rbp->b_flags & B_CACHE)) { 247 bqrelse(rbp); 248 goto no_read_ahead; 249 } 250 251 /* 252 * An error from the read-ahead bmap has nothing to do 253 * with the caller's original request. 254 */ 255 tmp_error = VOP_BMAP(vp, loffset, &doffset, 256 &burstbytes, NULL, BUF_CMD_READ); 257 if (tmp_error || doffset == NOOFFSET) { 258 rbp->b_flags |= B_INVAL; 259 brelse(rbp); 260 rbp = NULL; 261 goto no_read_ahead; 262 } 263 ntoread = burstbytes / blksize; 264 nblksread = (totread + blksize - 1) / blksize; 265 if (seqcount < nblksread) 266 seqcount = nblksread; 267 if (ntoread > seqcount) 268 ntoread = seqcount; 269 270 rbp->b_flags |= B_RAM/* | B_AGE*/; 271 if (burstbytes) { 272 rbp = cluster_rbuild(vp, filesize, loffset, 273 doffset, blksize, 274 ntoread, rbp, 1); 275 } else { 276 rbp->b_bio2.bio_offset = doffset; 277 } 278 #if defined(CLUSTERDEBUG) 279 if (rcluster) { 280 if (bp) 281 kprintf("A+(%lld,%d,%lld,%d) ", 282 rbp->b_loffset, rbp->b_bcount, 283 rbp->b_loffset - origoffset, 284 seqcount); 285 else 286 kprintf("A(%lld,%d,%lld,%d) ", 287 rbp->b_loffset, rbp->b_bcount, 288 rbp->b_loffset - origoffset, 289 seqcount); 290 } 291 #endif 292 rbp->b_flags &= ~(B_ERROR|B_INVAL); 293 rbp->b_flags |= B_ASYNC; 294 rbp->b_cmd = BUF_CMD_READ; 295 296 if ((rbp->b_flags & B_CLUSTER) == 0) 297 vfs_busy_pages(vp, rbp); 298 BUF_KERNPROC(rbp); /* B_ASYNC */ 299 vn_strategy(vp, &rbp->b_bio1); 300 } 301 no_read_ahead: 302 303 if (reqbp) 304 return (biowait(reqbp)); 305 else 306 return (error); 307 } 308 309 /* 310 * If blocks are contiguous on disk, use this to provide clustered 311 * read ahead. We will read as many blocks as possible sequentially 312 * and then parcel them up into logical blocks in the buffer hash table. 313 */ 314 static struct buf * 315 cluster_rbuild(struct vnode *vp, off_t filesize, off_t loffset, 316 off_t doffset, int blksize, int run, struct buf *fbp, int doasync) 317 { 318 struct buf *bp, *tbp; 319 off_t boffset; 320 int i, j; 321 int maxiosize = vmaxiosize(vp); 322 323 /* 324 * avoid a division 325 */ 326 while (loffset + run * blksize > filesize) { 327 --run; 328 } 329 330 tbp = fbp; 331 tbp->b_bio2.bio_offset = doffset; 332 if((tbp->b_flags & B_MALLOC) || 333 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1)) { 334 return tbp; 335 } 336 337 bp = trypbuf(&cluster_pbuf_freecnt); 338 if (bp == NULL) 339 return tbp; 340 341 /* 342 * We are synthesizing a buffer out of vm_page_t's, but 343 * if the block size is not page aligned then the starting 344 * address may not be either. Inherit the b_data offset 345 * from the original buffer. 346 */ 347 bp->b_data = (char *)((vm_offset_t)bp->b_data | 348 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 349 bp->b_flags |= B_ASYNC | B_CLUSTER | B_VMIO; 350 bp->b_cmd = BUF_CMD_READ; 351 bp->b_bio1.bio_done = cluster_callback; 352 bp->b_bio1.bio_caller_info1.cluster_head = NULL; 353 bp->b_bio1.bio_caller_info2.cluster_tail = NULL; 354 bp->b_loffset = loffset; 355 bp->b_bio2.bio_offset = doffset; 356 KASSERT(bp->b_loffset != NOOFFSET, 357 ("cluster_rbuild: no buffer offset")); 358 359 bp->b_bcount = 0; 360 bp->b_bufsize = 0; 361 bp->b_xio.xio_npages = 0; 362 363 for (boffset = doffset, i = 0; i < run; ++i, boffset += blksize) { 364 if (i) { 365 if ((bp->b_xio.xio_npages * PAGE_SIZE) + 366 round_page(blksize) > maxiosize) { 367 break; 368 } 369 370 /* 371 * Shortcut some checks and try to avoid buffers that 372 * would block in the lock. The same checks have to 373 * be made again after we officially get the buffer. 374 */ 375 tbp = getblk(vp, loffset + i * blksize, blksize, 376 GETBLK_SZMATCH|GETBLK_NOWAIT, 0); 377 if (tbp == NULL) 378 break; 379 for (j = 0; j < tbp->b_xio.xio_npages; j++) { 380 if (tbp->b_xio.xio_pages[j]->valid) 381 break; 382 } 383 if (j != tbp->b_xio.xio_npages) { 384 bqrelse(tbp); 385 break; 386 } 387 388 /* 389 * Stop scanning if the buffer is fuly valid 390 * (marked B_CACHE), or locked (may be doing a 391 * background write), or if the buffer is not 392 * VMIO backed. The clustering code can only deal 393 * with VMIO-backed buffers. 394 */ 395 if ((tbp->b_flags & (B_CACHE|B_LOCKED)) || 396 (tbp->b_flags & B_VMIO) == 0 || 397 (LIST_FIRST(&tbp->b_dep) != NULL && 398 buf_checkread(tbp)) 399 ) { 400 bqrelse(tbp); 401 break; 402 } 403 404 /* 405 * The buffer must be completely invalid in order to 406 * take part in the cluster. If it is partially valid 407 * then we stop. 408 */ 409 for (j = 0;j < tbp->b_xio.xio_npages; j++) { 410 if (tbp->b_xio.xio_pages[j]->valid) 411 break; 412 } 413 if (j != tbp->b_xio.xio_npages) { 414 bqrelse(tbp); 415 break; 416 } 417 418 /* 419 * Set a read-ahead mark as appropriate 420 */ 421 if (i == 1 || i == (run - 1)) 422 tbp->b_flags |= B_RAM; 423 424 /* 425 * Depress the priority of buffers not explicitly 426 * requested. 427 */ 428 /* tbp->b_flags |= B_AGE; */ 429 430 /* 431 * Set the block number if it isn't set, otherwise 432 * if it is make sure it matches the block number we 433 * expect. 434 */ 435 if (tbp->b_bio2.bio_offset == NOOFFSET) { 436 tbp->b_bio2.bio_offset = boffset; 437 } else if (tbp->b_bio2.bio_offset != boffset) { 438 brelse(tbp); 439 break; 440 } 441 } 442 /* 443 * The first buffer is setup async if doasync is specified. 444 * All other buffers in the cluster are setup async. This 445 * way the caller can decide how to deal with the requested 446 * buffer. 447 */ 448 if (i || doasync) 449 tbp->b_flags |= B_ASYNC; 450 tbp->b_cmd = BUF_CMD_READ; 451 BUF_KERNPROC(tbp); 452 cluster_append(&bp->b_bio1, tbp); 453 for (j = 0; j < tbp->b_xio.xio_npages; ++j) { 454 vm_page_t m; 455 m = tbp->b_xio.xio_pages[j]; 456 vm_page_io_start(m); 457 vm_object_pip_add(m->object, 1); 458 if ((bp->b_xio.xio_npages == 0) || 459 (bp->b_xio.xio_pages[bp->b_xio.xio_npages-1] != m)) { 460 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 461 bp->b_xio.xio_npages++; 462 } 463 if ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) 464 tbp->b_xio.xio_pages[j] = bogus_page; 465 } 466 /* 467 * XXX shouldn't this be += size for both, like in 468 * cluster_wbuild()? 469 * 470 * Don't inherit tbp->b_bufsize as it may be larger due to 471 * a non-page-aligned size. Instead just aggregate using 472 * 'size'. 473 */ 474 if (tbp->b_bcount != blksize) 475 kprintf("warning: tbp->b_bcount wrong %d vs %d\n", tbp->b_bcount, blksize); 476 if (tbp->b_bufsize != blksize) 477 kprintf("warning: tbp->b_bufsize wrong %d vs %d\n", tbp->b_bufsize, blksize); 478 bp->b_bcount += blksize; 479 bp->b_bufsize += blksize; 480 } 481 482 /* 483 * Fully valid pages in the cluster are already good and do not need 484 * to be re-read from disk. Replace the page with bogus_page 485 */ 486 for (j = 0; j < bp->b_xio.xio_npages; j++) { 487 if ((bp->b_xio.xio_pages[j]->valid & VM_PAGE_BITS_ALL) == 488 VM_PAGE_BITS_ALL) { 489 bp->b_xio.xio_pages[j] = bogus_page; 490 } 491 } 492 if (bp->b_bufsize > bp->b_kvasize) { 493 panic("cluster_rbuild: b_bufsize(%d) > b_kvasize(%d)", 494 bp->b_bufsize, bp->b_kvasize); 495 } 496 497 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 498 (vm_page_t *)bp->b_xio.xio_pages, bp->b_xio.xio_npages); 499 return (bp); 500 } 501 502 /* 503 * Cleanup after a clustered read or write. 504 * This is complicated by the fact that any of the buffers might have 505 * extra memory (if there were no empty buffer headers at allocbuf time) 506 * that we will need to shift around. 507 * 508 * The returned bio is &bp->b_bio1 509 */ 510 void 511 cluster_callback(struct bio *bio) 512 { 513 struct buf *bp = bio->bio_buf; 514 struct buf *tbp; 515 int error = 0; 516 517 /* 518 * Must propogate errors to all the components. A short read (EOF) 519 * is a critical error. 520 */ 521 if (bp->b_flags & B_ERROR) { 522 error = bp->b_error; 523 } else if (bp->b_bcount != bp->b_bufsize) { 524 panic("cluster_callback: unexpected EOF on cluster %p!", bio); 525 } 526 527 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_xio.xio_npages); 528 /* 529 * Move memory from the large cluster buffer into the component 530 * buffers and mark IO as done on these. Since the memory map 531 * is the same, no actual copying is required. 532 */ 533 while ((tbp = bio->bio_caller_info1.cluster_head) != NULL) { 534 bio->bio_caller_info1.cluster_head = tbp->b_cluster_next; 535 if (error) { 536 tbp->b_flags |= B_ERROR; 537 tbp->b_error = error; 538 } else { 539 tbp->b_dirtyoff = tbp->b_dirtyend = 0; 540 tbp->b_flags &= ~(B_ERROR|B_INVAL); 541 /* 542 * XXX the bdwrite()/bqrelse() issued during 543 * cluster building clears B_RELBUF (see bqrelse() 544 * comment). If direct I/O was specified, we have 545 * to restore it here to allow the buffer and VM 546 * to be freed. 547 */ 548 if (tbp->b_flags & B_DIRECT) 549 tbp->b_flags |= B_RELBUF; 550 } 551 biodone(&tbp->b_bio1); 552 } 553 relpbuf(bp, &cluster_pbuf_freecnt); 554 } 555 556 /* 557 * cluster_wbuild_wb: 558 * 559 * Implement modified write build for cluster. 560 * 561 * write_behind = 0 write behind disabled 562 * write_behind = 1 write behind normal (default) 563 * write_behind = 2 write behind backed-off 564 */ 565 566 static __inline int 567 cluster_wbuild_wb(struct vnode *vp, int blksize, off_t start_loffset, int len) 568 { 569 int r = 0; 570 571 switch(write_behind) { 572 case 2: 573 if (start_loffset < len) 574 break; 575 start_loffset -= len; 576 /* fall through */ 577 case 1: 578 r = cluster_wbuild(vp, blksize, start_loffset, len); 579 /* fall through */ 580 default: 581 /* fall through */ 582 break; 583 } 584 return(r); 585 } 586 587 /* 588 * Do clustered write for FFS. 589 * 590 * Three cases: 591 * 1. Write is not sequential (write asynchronously) 592 * Write is sequential: 593 * 2. beginning of cluster - begin cluster 594 * 3. middle of a cluster - add to cluster 595 * 4. end of a cluster - asynchronously write cluster 596 */ 597 void 598 cluster_write(struct buf *bp, off_t filesize, int blksize, int seqcount) 599 { 600 struct vnode *vp; 601 off_t loffset; 602 int maxclen, cursize; 603 int async; 604 605 vp = bp->b_vp; 606 if (vp->v_type == VREG) 607 async = vp->v_mount->mnt_flag & MNT_ASYNC; 608 else 609 async = 0; 610 loffset = bp->b_loffset; 611 KASSERT(bp->b_loffset != NOOFFSET, 612 ("cluster_write: no buffer offset")); 613 614 /* Initialize vnode to beginning of file. */ 615 if (loffset == 0) 616 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0; 617 618 if (vp->v_clen == 0 || loffset != vp->v_lastw + blksize || 619 bp->b_bio2.bio_offset == NOOFFSET || 620 (bp->b_bio2.bio_offset != vp->v_lasta + blksize)) { 621 maxclen = vmaxiosize(vp); 622 if (vp->v_clen != 0) { 623 /* 624 * Next block is not sequential. 625 * 626 * If we are not writing at end of file, the process 627 * seeked to another point in the file since its last 628 * write, or we have reached our maximum cluster size, 629 * then push the previous cluster. Otherwise try 630 * reallocating to make it sequential. 631 * 632 * Change to algorithm: only push previous cluster if 633 * it was sequential from the point of view of the 634 * seqcount heuristic, otherwise leave the buffer 635 * intact so we can potentially optimize the I/O 636 * later on in the buf_daemon or update daemon 637 * flush. 638 */ 639 cursize = vp->v_lastw - vp->v_cstart + blksize; 640 if (bp->b_loffset + blksize != filesize || 641 loffset != vp->v_lastw + blksize || vp->v_clen <= cursize) { 642 if (!async && seqcount > 0) { 643 cluster_wbuild_wb(vp, blksize, 644 vp->v_cstart, cursize); 645 } 646 } else { 647 struct buf **bpp, **endbp; 648 struct cluster_save *buflist; 649 650 buflist = cluster_collectbufs(vp, bp, blksize); 651 endbp = &buflist->bs_children 652 [buflist->bs_nchildren - 1]; 653 if (VOP_REALLOCBLKS(vp, buflist)) { 654 /* 655 * Failed, push the previous cluster 656 * if *really* writing sequentially 657 * in the logical file (seqcount > 1), 658 * otherwise delay it in the hopes that 659 * the low level disk driver can 660 * optimize the write ordering. 661 */ 662 for (bpp = buflist->bs_children; 663 bpp < endbp; bpp++) 664 brelse(*bpp); 665 kfree(buflist, M_SEGMENT); 666 if (seqcount > 1) { 667 cluster_wbuild_wb(vp, 668 blksize, vp->v_cstart, 669 cursize); 670 } 671 } else { 672 /* 673 * Succeeded, keep building cluster. 674 */ 675 for (bpp = buflist->bs_children; 676 bpp <= endbp; bpp++) 677 bdwrite(*bpp); 678 kfree(buflist, M_SEGMENT); 679 vp->v_lastw = loffset; 680 vp->v_lasta = bp->b_bio2.bio_offset; 681 return; 682 } 683 } 684 } 685 /* 686 * Consider beginning a cluster. If at end of file, make 687 * cluster as large as possible, otherwise find size of 688 * existing cluster. 689 */ 690 if ((vp->v_type == VREG) && 691 bp->b_loffset + blksize != filesize && 692 (bp->b_bio2.bio_offset == NOOFFSET) && 693 (VOP_BMAP(vp, loffset, &bp->b_bio2.bio_offset, &maxclen, NULL, BUF_CMD_WRITE) || 694 bp->b_bio2.bio_offset == NOOFFSET)) { 695 bawrite(bp); 696 vp->v_clen = 0; 697 vp->v_lasta = bp->b_bio2.bio_offset; 698 vp->v_cstart = loffset + blksize; 699 vp->v_lastw = loffset; 700 return; 701 } 702 if (maxclen > blksize) 703 vp->v_clen = maxclen - blksize; 704 else 705 vp->v_clen = 0; 706 if (!async && vp->v_clen == 0) { /* I/O not contiguous */ 707 vp->v_cstart = loffset + blksize; 708 bawrite(bp); 709 } else { /* Wait for rest of cluster */ 710 vp->v_cstart = loffset; 711 bdwrite(bp); 712 } 713 } else if (loffset == vp->v_cstart + vp->v_clen) { 714 /* 715 * At end of cluster, write it out if seqcount tells us we 716 * are operating sequentially, otherwise let the buf or 717 * update daemon handle it. 718 */ 719 bdwrite(bp); 720 if (seqcount > 1) 721 cluster_wbuild_wb(vp, blksize, vp->v_cstart, 722 vp->v_clen + blksize); 723 vp->v_clen = 0; 724 vp->v_cstart = loffset + blksize; 725 } else if (vm_page_count_severe()) { 726 /* 727 * We are low on memory, get it going NOW 728 */ 729 bawrite(bp); 730 } else { 731 /* 732 * In the middle of a cluster, so just delay the I/O for now. 733 */ 734 bdwrite(bp); 735 } 736 vp->v_lastw = loffset; 737 vp->v_lasta = bp->b_bio2.bio_offset; 738 } 739 740 741 /* 742 * This is an awful lot like cluster_rbuild...wish they could be combined. 743 * The last lbn argument is the current block on which I/O is being 744 * performed. Check to see that it doesn't fall in the middle of 745 * the current block (if last_bp == NULL). 746 */ 747 int 748 cluster_wbuild(struct vnode *vp, int blksize, off_t start_loffset, int bytes) 749 { 750 struct buf *bp, *tbp; 751 int i, j; 752 int totalwritten = 0; 753 int maxiosize = vmaxiosize(vp); 754 755 while (bytes > 0) { 756 /* 757 * If the buffer is not delayed-write (i.e. dirty), or it 758 * is delayed-write but either locked or inval, it cannot 759 * partake in the clustered write. 760 */ 761 tbp = findblk(vp, start_loffset, FINDBLK_NBLOCK); 762 if (tbp == NULL || 763 (tbp->b_flags & (B_LOCKED | B_INVAL | B_DELWRI)) != B_DELWRI || 764 (LIST_FIRST(&tbp->b_dep) && buf_checkwrite(tbp))) { 765 if (tbp) 766 BUF_UNLOCK(tbp); 767 start_loffset += blksize; 768 bytes -= blksize; 769 continue; 770 } 771 bremfree(tbp); 772 KKASSERT(tbp->b_cmd == BUF_CMD_DONE); 773 774 /* 775 * Extra memory in the buffer, punt on this buffer. 776 * XXX we could handle this in most cases, but we would 777 * have to push the extra memory down to after our max 778 * possible cluster size and then potentially pull it back 779 * up if the cluster was terminated prematurely--too much 780 * hassle. 781 */ 782 if (((tbp->b_flags & (B_CLUSTEROK|B_MALLOC)) != B_CLUSTEROK) || 783 (tbp->b_bcount != tbp->b_bufsize) || 784 (tbp->b_bcount != blksize) || 785 (bytes == blksize) || 786 ((bp = getpbuf(&cluster_pbuf_freecnt)) == NULL)) { 787 totalwritten += tbp->b_bufsize; 788 bawrite(tbp); 789 start_loffset += blksize; 790 bytes -= blksize; 791 continue; 792 } 793 794 /* 795 * Set up the pbuf. Track our append point with b_bcount 796 * and b_bufsize. b_bufsize is not used by the device but 797 * our caller uses it to loop clusters and we use it to 798 * detect a premature EOF on the block device. 799 */ 800 bp->b_bcount = 0; 801 bp->b_bufsize = 0; 802 bp->b_xio.xio_npages = 0; 803 bp->b_loffset = tbp->b_loffset; 804 bp->b_bio2.bio_offset = tbp->b_bio2.bio_offset; 805 806 /* 807 * We are synthesizing a buffer out of vm_page_t's, but 808 * if the block size is not page aligned then the starting 809 * address may not be either. Inherit the b_data offset 810 * from the original buffer. 811 */ 812 bp->b_data = (char *)((vm_offset_t)bp->b_data | 813 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 814 bp->b_flags &= ~B_ERROR; 815 bp->b_flags |= B_CLUSTER | B_BNOCLIP | 816 (tbp->b_flags & (B_VMIO | B_NEEDCOMMIT)); 817 bp->b_bio1.bio_done = cluster_callback; 818 bp->b_bio1.bio_caller_info1.cluster_head = NULL; 819 bp->b_bio1.bio_caller_info2.cluster_tail = NULL; 820 821 /* 822 * From this location in the file, scan forward to see 823 * if there are buffers with adjacent data that need to 824 * be written as well. 825 */ 826 for (i = 0; i < bytes; (i += blksize), (start_loffset += blksize)) { 827 if (i != 0) { /* If not the first buffer */ 828 tbp = findblk(vp, start_loffset, 829 FINDBLK_NBLOCK); 830 /* 831 * Buffer not found or could not be locked 832 * non-blocking. 833 */ 834 if (tbp == NULL) 835 break; 836 837 /* 838 * If it IS in core, but has different 839 * characteristics, then don't cluster 840 * with it. 841 */ 842 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK | 843 B_INVAL | B_DELWRI | B_NEEDCOMMIT)) 844 != (B_DELWRI | B_CLUSTEROK | 845 (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) || 846 (tbp->b_flags & B_LOCKED) || 847 (LIST_FIRST(&tbp->b_dep) && 848 buf_checkwrite(tbp)) 849 ) { 850 BUF_UNLOCK(tbp); 851 break; 852 } 853 854 /* 855 * Check that the combined cluster 856 * would make sense with regard to pages 857 * and would not be too large 858 */ 859 if ((tbp->b_bcount != blksize) || 860 ((bp->b_bio2.bio_offset + i) != 861 tbp->b_bio2.bio_offset) || 862 ((tbp->b_xio.xio_npages + bp->b_xio.xio_npages) > 863 (maxiosize / PAGE_SIZE))) { 864 BUF_UNLOCK(tbp); 865 break; 866 } 867 /* 868 * Ok, it's passed all the tests, 869 * so remove it from the free list 870 * and mark it busy. We will use it. 871 */ 872 bremfree(tbp); 873 KKASSERT(tbp->b_cmd == BUF_CMD_DONE); 874 } /* end of code for non-first buffers only */ 875 876 /* 877 * If the IO is via the VM then we do some 878 * special VM hackery (yuck). Since the buffer's 879 * block size may not be page-aligned it is possible 880 * for a page to be shared between two buffers. We 881 * have to get rid of the duplication when building 882 * the cluster. 883 */ 884 if (tbp->b_flags & B_VMIO) { 885 vm_page_t m; 886 887 if (i != 0) { /* if not first buffer */ 888 for (j = 0; j < tbp->b_xio.xio_npages; ++j) { 889 m = tbp->b_xio.xio_pages[j]; 890 if (m->flags & PG_BUSY) { 891 bqrelse(tbp); 892 goto finishcluster; 893 } 894 } 895 } 896 897 for (j = 0; j < tbp->b_xio.xio_npages; ++j) { 898 m = tbp->b_xio.xio_pages[j]; 899 vm_page_io_start(m); 900 vm_object_pip_add(m->object, 1); 901 if ((bp->b_xio.xio_npages == 0) || 902 (bp->b_xio.xio_pages[bp->b_xio.xio_npages - 1] != m)) { 903 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 904 bp->b_xio.xio_npages++; 905 } 906 } 907 } 908 bp->b_bcount += blksize; 909 bp->b_bufsize += blksize; 910 911 bundirty(tbp); 912 tbp->b_flags &= ~B_ERROR; 913 tbp->b_flags |= B_ASYNC; 914 tbp->b_cmd = BUF_CMD_WRITE; 915 BUF_KERNPROC(tbp); 916 cluster_append(&bp->b_bio1, tbp); 917 918 /* 919 * check for latent dependencies to be handled 920 */ 921 if (LIST_FIRST(&tbp->b_dep) != NULL) 922 buf_start(tbp); 923 } 924 finishcluster: 925 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 926 (vm_page_t *) bp->b_xio.xio_pages, bp->b_xio.xio_npages); 927 if (bp->b_bufsize > bp->b_kvasize) { 928 panic( 929 "cluster_wbuild: b_bufsize(%d) > b_kvasize(%d)\n", 930 bp->b_bufsize, bp->b_kvasize); 931 } 932 totalwritten += bp->b_bufsize; 933 bp->b_dirtyoff = 0; 934 bp->b_dirtyend = bp->b_bufsize; 935 bp->b_flags |= B_ASYNC; 936 bp->b_cmd = BUF_CMD_WRITE; 937 vfs_busy_pages(vp, bp); 938 bp->b_runningbufspace = bp->b_bufsize; 939 if (bp->b_runningbufspace) { 940 runningbufspace += bp->b_runningbufspace; 941 ++runningbufcount; 942 } 943 BUF_KERNPROC(bp); /* B_ASYNC */ 944 vn_strategy(vp, &bp->b_bio1); 945 946 bytes -= i; 947 } 948 return totalwritten; 949 } 950 951 /* 952 * Collect together all the buffers in a cluster. 953 * Plus add one additional buffer. 954 */ 955 static struct cluster_save * 956 cluster_collectbufs(struct vnode *vp, struct buf *last_bp, int blksize) 957 { 958 struct cluster_save *buflist; 959 struct buf *bp; 960 off_t loffset; 961 int i, len; 962 963 len = (int)(vp->v_lastw - vp->v_cstart + blksize) / blksize; 964 buflist = kmalloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist), 965 M_SEGMENT, M_WAITOK); 966 buflist->bs_nchildren = 0; 967 buflist->bs_children = (struct buf **) (buflist + 1); 968 for (loffset = vp->v_cstart, i = 0; i < len; (loffset += blksize), i++) { 969 (void) bread(vp, loffset, last_bp->b_bcount, &bp); 970 buflist->bs_children[i] = bp; 971 if (bp->b_bio2.bio_offset == NOOFFSET) { 972 VOP_BMAP(bp->b_vp, bp->b_loffset, 973 &bp->b_bio2.bio_offset, 974 NULL, NULL, BUF_CMD_WRITE); 975 } 976 } 977 buflist->bs_children[i] = bp = last_bp; 978 if (bp->b_bio2.bio_offset == NOOFFSET) { 979 VOP_BMAP(bp->b_vp, bp->b_loffset, &bp->b_bio2.bio_offset, 980 NULL, NULL, BUF_CMD_WRITE); 981 } 982 buflist->bs_nchildren = i + 1; 983 return (buflist); 984 } 985 986 void 987 cluster_append(struct bio *bio, struct buf *tbp) 988 { 989 tbp->b_cluster_next = NULL; 990 if (bio->bio_caller_info1.cluster_head == NULL) { 991 bio->bio_caller_info1.cluster_head = tbp; 992 bio->bio_caller_info2.cluster_tail = tbp; 993 } else { 994 bio->bio_caller_info2.cluster_tail->b_cluster_next = tbp; 995 bio->bio_caller_info2.cluster_tail = tbp; 996 } 997 } 998 999