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 #include <machine/limits.h> 60 61 #if defined(CLUSTERDEBUG) 62 #include <sys/sysctl.h> 63 static int rcluster= 0; 64 SYSCTL_INT(_debug, OID_AUTO, rcluster, CTLFLAG_RW, &rcluster, 0, ""); 65 #endif 66 67 static MALLOC_DEFINE(M_SEGMENT, "cluster_save", "cluster_save buffer"); 68 69 static struct cluster_save * 70 cluster_collectbufs (struct vnode *vp, struct buf *last_bp, 71 int blksize); 72 static struct buf * 73 cluster_rbuild (struct vnode *vp, off_t filesize, off_t loffset, 74 off_t doffset, int blksize, int run, 75 struct buf *fbp); 76 static void cluster_callback (struct bio *); 77 78 79 static int write_behind = 1; 80 SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0, ""); 81 82 extern vm_page_t bogus_page; 83 84 extern int cluster_pbuf_freecnt; 85 86 /* 87 * Maximum number of blocks for read-ahead. 88 */ 89 #define MAXRA 32 90 91 /* 92 * This replaces bread. 93 */ 94 int 95 cluster_read(struct vnode *vp, off_t filesize, off_t loffset, 96 int blksize, size_t resid, int seqcount, struct buf **bpp) 97 { 98 struct buf *bp, *rbp, *reqbp; 99 off_t origoffset; 100 off_t doffset; 101 int error; 102 int i; 103 int maxra, racluster; 104 int totread; 105 106 error = 0; 107 totread = (resid > INT_MAX) ? INT_MAX : (int)resid; 108 109 /* 110 * Try to limit the amount of read-ahead by a few 111 * ad-hoc parameters. This needs work!!! 112 */ 113 racluster = vmaxiosize(vp) / blksize; 114 maxra = 2 * racluster + (totread / blksize); 115 if (maxra > MAXRA) 116 maxra = MAXRA; 117 if (maxra > nbuf/8) 118 maxra = nbuf/8; 119 120 /* 121 * Get the requested block. 122 */ 123 *bpp = reqbp = bp = getblk(vp, loffset, blksize, 0, 0); 124 origoffset = loffset; 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 struct buf *tbp; 138 bp->b_flags &= ~B_RAM; 139 140 /* 141 * Set read-ahead-mark only if we can passively lock 142 * the buffer. Note that with these flags the bp 143 * could very exist even though NULL is returned. 144 */ 145 for (i = 1; i < maxra; i++) { 146 tbp = findblk(vp, loffset + i * blksize, 147 FINDBLK_NBLOCK); 148 if (tbp == NULL) 149 break; 150 if (((i % racluster) == (racluster - 1)) || 151 (i == (maxra - 1))) { 152 tbp->b_flags |= B_RAM; 153 } 154 BUF_UNLOCK(tbp); 155 } 156 if (i >= maxra) 157 return 0; 158 loffset += i * blksize; 159 } 160 reqbp = bp = NULL; 161 } else { 162 off_t firstread = bp->b_loffset; 163 int nblks; 164 165 /* 166 * Set-up synchronous read for bp. 167 */ 168 bp->b_cmd = BUF_CMD_READ; 169 bp->b_bio1.bio_done = biodone_sync; 170 bp->b_bio1.bio_flags |= BIO_SYNC; 171 172 KASSERT(firstread != NOOFFSET, 173 ("cluster_read: no buffer offset")); 174 if (firstread + totread > filesize) 175 totread = (int)(filesize - firstread); 176 nblks = totread / blksize; 177 if (nblks) { 178 int burstbytes; 179 180 if (nblks > racluster) 181 nblks = racluster; 182 183 error = VOP_BMAP(vp, loffset, &doffset, 184 &burstbytes, NULL, BUF_CMD_READ); 185 if (error) 186 goto single_block_read; 187 if (doffset == NOOFFSET) 188 goto single_block_read; 189 if (burstbytes < blksize * 2) 190 goto single_block_read; 191 if (nblks > burstbytes / blksize) 192 nblks = burstbytes / blksize; 193 194 bp = cluster_rbuild(vp, filesize, loffset, 195 doffset, blksize, nblks, bp); 196 loffset += bp->b_bufsize; 197 } else { 198 single_block_read: 199 /* 200 * if it isn't in the cache, then get a chunk from 201 * disk if sequential, otherwise just get the block. 202 */ 203 bp->b_flags |= B_RAM; 204 loffset += blksize; 205 } 206 } 207 208 /* 209 * If B_CACHE was not set issue bp. bp will either be an 210 * asynchronous cluster buf or a synchronous single-buf. 211 * If it is a single buf it will be the same as reqbp. 212 * 213 * NOTE: Once an async cluster buf is issued bp becomes invalid. 214 */ 215 if (bp) { 216 #if defined(CLUSTERDEBUG) 217 if (rcluster) 218 kprintf("S(%lld,%d,%d) ", 219 bp->b_loffset, bp->b_bcount, seqcount); 220 #endif 221 if ((bp->b_flags & B_CLUSTER) == 0) 222 vfs_busy_pages(vp, bp); 223 bp->b_flags &= ~(B_ERROR|B_INVAL); 224 vn_strategy(vp, &bp->b_bio1); 225 error = 0; 226 /* bp invalid now */ 227 } 228 229 /* 230 * If we have been doing sequential I/O, then do some read-ahead. 231 * 232 * Only mess with buffers which we can immediately lock. HAMMER 233 * will do device-readahead irrespective of what the blocks 234 * represent. 235 */ 236 rbp = NULL; 237 if (!error && 238 seqcount && 239 loffset < origoffset + seqcount * blksize && 240 loffset + blksize <= filesize 241 ) { 242 int nblksread; 243 int ntoread; 244 int burstbytes; 245 int tmp_error; 246 247 rbp = getblk(vp, loffset, blksize, 248 GETBLK_SZMATCH|GETBLK_NOWAIT, 0); 249 if (rbp == NULL) 250 goto no_read_ahead; 251 if ((rbp->b_flags & B_CACHE)) { 252 bqrelse(rbp); 253 goto no_read_ahead; 254 } 255 256 /* 257 * An error from the read-ahead bmap has nothing to do 258 * with the caller's original request. 259 */ 260 tmp_error = VOP_BMAP(vp, loffset, &doffset, 261 &burstbytes, NULL, BUF_CMD_READ); 262 if (tmp_error || doffset == NOOFFSET) { 263 rbp->b_flags |= B_INVAL; 264 brelse(rbp); 265 rbp = NULL; 266 goto no_read_ahead; 267 } 268 ntoread = burstbytes / blksize; 269 nblksread = (totread + blksize - 1) / blksize; 270 if (seqcount < nblksread) 271 seqcount = nblksread; 272 if (ntoread > seqcount) 273 ntoread = seqcount; 274 275 /* 276 * rbp: async read 277 */ 278 rbp->b_cmd = BUF_CMD_READ; 279 rbp->b_flags |= B_RAM/* | B_AGE*/; 280 281 if (burstbytes) { 282 rbp = cluster_rbuild(vp, filesize, loffset, 283 doffset, blksize, 284 ntoread, rbp); 285 } else { 286 rbp->b_bio2.bio_offset = doffset; 287 } 288 #if defined(CLUSTERDEBUG) 289 if (rcluster) { 290 if (bp) 291 kprintf("A+(%lld,%d,%lld,%d) ", 292 rbp->b_loffset, rbp->b_bcount, 293 rbp->b_loffset - origoffset, 294 seqcount); 295 else 296 kprintf("A(%lld,%d,%lld,%d) ", 297 rbp->b_loffset, rbp->b_bcount, 298 rbp->b_loffset - origoffset, 299 seqcount); 300 } 301 #endif 302 rbp->b_flags &= ~(B_ERROR|B_INVAL); 303 304 if ((rbp->b_flags & B_CLUSTER) == 0) 305 vfs_busy_pages(vp, rbp); 306 BUF_KERNPROC(rbp); 307 vn_strategy(vp, &rbp->b_bio1); 308 /* rbp invalid now */ 309 } 310 311 /* 312 * Wait for our original buffer to complete its I/O. reqbp will 313 * be NULL if the original buffer was B_CACHE. We are returning 314 * (*bpp) which is the same as reqbp when reqbp != NULL. 315 */ 316 no_read_ahead: 317 if (reqbp) { 318 KKASSERT(reqbp->b_bio1.bio_flags & BIO_SYNC); 319 error = biowait(&reqbp->b_bio1, "clurd"); 320 } 321 return (error); 322 } 323 324 /* 325 * If blocks are contiguous on disk, use this to provide clustered 326 * read ahead. We will read as many blocks as possible sequentially 327 * and then parcel them up into logical blocks in the buffer hash table. 328 * 329 * This function either returns a cluster buf or it returns fbp. fbp is 330 * already expected to be set up as a synchronous or asynchronous request. 331 * 332 * If a cluster buf is returned it will always be async. 333 */ 334 static struct buf * 335 cluster_rbuild(struct vnode *vp, off_t filesize, off_t loffset, off_t doffset, 336 int blksize, int run, struct buf *fbp) 337 { 338 struct buf *bp, *tbp; 339 off_t boffset; 340 int i, j; 341 int maxiosize = vmaxiosize(vp); 342 343 /* 344 * avoid a division 345 */ 346 while (loffset + run * blksize > filesize) { 347 --run; 348 } 349 350 tbp = fbp; 351 tbp->b_bio2.bio_offset = doffset; 352 if((tbp->b_flags & B_MALLOC) || 353 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1)) { 354 return tbp; 355 } 356 357 bp = trypbuf(&cluster_pbuf_freecnt); 358 if (bp == NULL) { 359 return tbp; 360 } 361 362 /* 363 * We are synthesizing a buffer out of vm_page_t's, but 364 * if the block size is not page aligned then the starting 365 * address may not be either. Inherit the b_data offset 366 * from the original buffer. 367 */ 368 bp->b_data = (char *)((vm_offset_t)bp->b_data | 369 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 370 bp->b_flags |= B_CLUSTER | B_VMIO; 371 bp->b_cmd = BUF_CMD_READ; 372 bp->b_bio1.bio_done = cluster_callback; /* default to async */ 373 bp->b_bio1.bio_caller_info1.cluster_head = NULL; 374 bp->b_bio1.bio_caller_info2.cluster_tail = NULL; 375 bp->b_loffset = loffset; 376 bp->b_bio2.bio_offset = doffset; 377 KASSERT(bp->b_loffset != NOOFFSET, 378 ("cluster_rbuild: no buffer offset")); 379 380 bp->b_bcount = 0; 381 bp->b_bufsize = 0; 382 bp->b_xio.xio_npages = 0; 383 384 for (boffset = doffset, i = 0; i < run; ++i, boffset += blksize) { 385 if (i) { 386 if ((bp->b_xio.xio_npages * PAGE_SIZE) + 387 round_page(blksize) > maxiosize) { 388 break; 389 } 390 391 /* 392 * Shortcut some checks and try to avoid buffers that 393 * would block in the lock. The same checks have to 394 * be made again after we officially get the buffer. 395 */ 396 tbp = getblk(vp, loffset + i * blksize, blksize, 397 GETBLK_SZMATCH|GETBLK_NOWAIT, 0); 398 if (tbp == NULL) 399 break; 400 for (j = 0; j < tbp->b_xio.xio_npages; j++) { 401 if (tbp->b_xio.xio_pages[j]->valid) 402 break; 403 } 404 if (j != tbp->b_xio.xio_npages) { 405 bqrelse(tbp); 406 break; 407 } 408 409 /* 410 * Stop scanning if the buffer is fuly 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. 415 */ 416 if ((tbp->b_flags & (B_CACHE|B_LOCKED)) || 417 (tbp->b_flags & B_VMIO) == 0 || 418 (LIST_FIRST(&tbp->b_dep) != NULL && 419 buf_checkread(tbp)) 420 ) { 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 for (j = 0;j < tbp->b_xio.xio_npages; j++) { 431 if (tbp->b_xio.xio_pages[j]->valid) 432 break; 433 } 434 if (j != tbp->b_xio.xio_npages) { 435 bqrelse(tbp); 436 break; 437 } 438 439 /* 440 * Set a read-ahead mark as appropriate 441 */ 442 if (i == 1 || i == (run - 1)) 443 tbp->b_flags |= B_RAM; 444 445 /* 446 * Depress the priority of buffers not explicitly 447 * requested. 448 */ 449 /* tbp->b_flags |= B_AGE; */ 450 451 /* 452 * Set the block number if it isn't set, otherwise 453 * if it is make sure it matches the block number we 454 * expect. 455 */ 456 if (tbp->b_bio2.bio_offset == NOOFFSET) { 457 tbp->b_bio2.bio_offset = boffset; 458 } else if (tbp->b_bio2.bio_offset != boffset) { 459 brelse(tbp); 460 break; 461 } 462 } 463 464 /* 465 * The passed-in tbp (i == 0) will already be set up for 466 * async or sync operation. All other tbp's acquire in 467 * our loop are set up for async operation. 468 */ 469 tbp->b_cmd = BUF_CMD_READ; 470 BUF_KERNPROC(tbp); 471 cluster_append(&bp->b_bio1, tbp); 472 for (j = 0; j < tbp->b_xio.xio_npages; ++j) { 473 vm_page_t m; 474 m = tbp->b_xio.xio_pages[j]; 475 vm_page_io_start(m); 476 vm_object_pip_add(m->object, 1); 477 if ((bp->b_xio.xio_npages == 0) || 478 (bp->b_xio.xio_pages[bp->b_xio.xio_npages-1] != m)) { 479 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 480 bp->b_xio.xio_npages++; 481 } 482 if ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) 483 tbp->b_xio.xio_pages[j] = bogus_page; 484 } 485 /* 486 * XXX shouldn't this be += size for both, like in 487 * cluster_wbuild()? 488 * 489 * Don't inherit tbp->b_bufsize as it may be larger due to 490 * a non-page-aligned size. Instead just aggregate using 491 * 'size'. 492 */ 493 if (tbp->b_bcount != blksize) 494 kprintf("warning: tbp->b_bcount wrong %d vs %d\n", tbp->b_bcount, blksize); 495 if (tbp->b_bufsize != blksize) 496 kprintf("warning: tbp->b_bufsize wrong %d vs %d\n", tbp->b_bufsize, blksize); 497 bp->b_bcount += blksize; 498 bp->b_bufsize += blksize; 499 } 500 501 /* 502 * Fully valid pages in the cluster are already good and do not need 503 * to be re-read from disk. Replace the page with bogus_page 504 */ 505 for (j = 0; j < bp->b_xio.xio_npages; j++) { 506 if ((bp->b_xio.xio_pages[j]->valid & VM_PAGE_BITS_ALL) == 507 VM_PAGE_BITS_ALL) { 508 bp->b_xio.xio_pages[j] = bogus_page; 509 } 510 } 511 if (bp->b_bufsize > bp->b_kvasize) { 512 panic("cluster_rbuild: b_bufsize(%d) > b_kvasize(%d)", 513 bp->b_bufsize, bp->b_kvasize); 514 } 515 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 516 (vm_page_t *)bp->b_xio.xio_pages, bp->b_xio.xio_npages); 517 BUF_KERNPROC(bp); 518 return (bp); 519 } 520 521 /* 522 * Cleanup after a clustered read or write. 523 * This is complicated by the fact that any of the buffers might have 524 * extra memory (if there were no empty buffer headers at allocbuf time) 525 * that we will need to shift around. 526 * 527 * The returned bio is &bp->b_bio1 528 */ 529 void 530 cluster_callback(struct bio *bio) 531 { 532 struct buf *bp = bio->bio_buf; 533 struct buf *tbp; 534 int error = 0; 535 536 /* 537 * Must propogate errors to all the components. A short read (EOF) 538 * is a critical error. 539 */ 540 if (bp->b_flags & B_ERROR) { 541 error = bp->b_error; 542 } else if (bp->b_bcount != bp->b_bufsize) { 543 panic("cluster_callback: unexpected EOF on cluster %p!", bio); 544 } 545 546 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_xio.xio_npages); 547 /* 548 * Move memory from the large cluster buffer into the component 549 * buffers and mark IO as done on these. Since the memory map 550 * is the same, no actual copying is required. 551 */ 552 while ((tbp = bio->bio_caller_info1.cluster_head) != NULL) { 553 bio->bio_caller_info1.cluster_head = tbp->b_cluster_next; 554 if (error) { 555 tbp->b_flags |= B_ERROR; 556 tbp->b_error = error; 557 } else { 558 tbp->b_dirtyoff = tbp->b_dirtyend = 0; 559 tbp->b_flags &= ~(B_ERROR|B_INVAL); 560 /* 561 * XXX the bdwrite()/bqrelse() issued during 562 * cluster building clears B_RELBUF (see bqrelse() 563 * comment). If direct I/O was specified, we have 564 * to restore it here to allow the buffer and VM 565 * to be freed. 566 */ 567 if (tbp->b_flags & B_DIRECT) 568 tbp->b_flags |= B_RELBUF; 569 } 570 biodone(&tbp->b_bio1); 571 } 572 relpbuf(bp, &cluster_pbuf_freecnt); 573 } 574 575 /* 576 * cluster_wbuild_wb: 577 * 578 * Implement modified write build for cluster. 579 * 580 * write_behind = 0 write behind disabled 581 * write_behind = 1 write behind normal (default) 582 * write_behind = 2 write behind backed-off 583 */ 584 585 static __inline int 586 cluster_wbuild_wb(struct vnode *vp, int blksize, off_t start_loffset, int len) 587 { 588 int r = 0; 589 590 switch(write_behind) { 591 case 2: 592 if (start_loffset < len) 593 break; 594 start_loffset -= len; 595 /* fall through */ 596 case 1: 597 r = cluster_wbuild(vp, blksize, start_loffset, len); 598 /* fall through */ 599 default: 600 /* fall through */ 601 break; 602 } 603 return(r); 604 } 605 606 /* 607 * Do clustered write for FFS. 608 * 609 * Three cases: 610 * 1. Write is not sequential (write asynchronously) 611 * Write is sequential: 612 * 2. beginning of cluster - begin cluster 613 * 3. middle of a cluster - add to cluster 614 * 4. end of a cluster - asynchronously write cluster 615 */ 616 void 617 cluster_write(struct buf *bp, off_t filesize, int blksize, int seqcount) 618 { 619 struct vnode *vp; 620 off_t loffset; 621 int maxclen, cursize; 622 int async; 623 624 vp = bp->b_vp; 625 if (vp->v_type == VREG) 626 async = vp->v_mount->mnt_flag & MNT_ASYNC; 627 else 628 async = 0; 629 loffset = bp->b_loffset; 630 KASSERT(bp->b_loffset != NOOFFSET, 631 ("cluster_write: no buffer offset")); 632 633 /* Initialize vnode to beginning of file. */ 634 if (loffset == 0) 635 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0; 636 637 if (vp->v_clen == 0 || loffset != vp->v_lastw + blksize || 638 bp->b_bio2.bio_offset == NOOFFSET || 639 (bp->b_bio2.bio_offset != vp->v_lasta + blksize)) { 640 maxclen = vmaxiosize(vp); 641 if (vp->v_clen != 0) { 642 /* 643 * Next block is not sequential. 644 * 645 * If we are not writing at end of file, the process 646 * seeked to another point in the file since its last 647 * write, or we have reached our maximum cluster size, 648 * then push the previous cluster. Otherwise try 649 * reallocating to make it sequential. 650 * 651 * Change to algorithm: only push previous cluster if 652 * it was sequential from the point of view of the 653 * seqcount heuristic, otherwise leave the buffer 654 * intact so we can potentially optimize the I/O 655 * later on in the buf_daemon or update daemon 656 * flush. 657 */ 658 cursize = vp->v_lastw - vp->v_cstart + blksize; 659 if (bp->b_loffset + blksize != filesize || 660 loffset != vp->v_lastw + blksize || vp->v_clen <= cursize) { 661 if (!async && seqcount > 0) { 662 cluster_wbuild_wb(vp, blksize, 663 vp->v_cstart, cursize); 664 } 665 } else { 666 struct buf **bpp, **endbp; 667 struct cluster_save *buflist; 668 669 buflist = cluster_collectbufs(vp, bp, blksize); 670 endbp = &buflist->bs_children 671 [buflist->bs_nchildren - 1]; 672 if (VOP_REALLOCBLKS(vp, buflist)) { 673 /* 674 * Failed, push the previous cluster 675 * if *really* writing sequentially 676 * in the logical file (seqcount > 1), 677 * otherwise delay it in the hopes that 678 * the low level disk driver can 679 * optimize the write ordering. 680 */ 681 for (bpp = buflist->bs_children; 682 bpp < endbp; bpp++) 683 brelse(*bpp); 684 kfree(buflist, M_SEGMENT); 685 if (seqcount > 1) { 686 cluster_wbuild_wb(vp, 687 blksize, vp->v_cstart, 688 cursize); 689 } 690 } else { 691 /* 692 * Succeeded, keep building cluster. 693 */ 694 for (bpp = buflist->bs_children; 695 bpp <= endbp; bpp++) 696 bdwrite(*bpp); 697 kfree(buflist, M_SEGMENT); 698 vp->v_lastw = loffset; 699 vp->v_lasta = bp->b_bio2.bio_offset; 700 return; 701 } 702 } 703 } 704 /* 705 * Consider beginning a cluster. If at end of file, make 706 * cluster as large as possible, otherwise find size of 707 * existing cluster. 708 */ 709 if ((vp->v_type == VREG) && 710 bp->b_loffset + blksize != filesize && 711 (bp->b_bio2.bio_offset == NOOFFSET) && 712 (VOP_BMAP(vp, loffset, &bp->b_bio2.bio_offset, &maxclen, NULL, BUF_CMD_WRITE) || 713 bp->b_bio2.bio_offset == NOOFFSET)) { 714 bawrite(bp); 715 vp->v_clen = 0; 716 vp->v_lasta = bp->b_bio2.bio_offset; 717 vp->v_cstart = loffset + blksize; 718 vp->v_lastw = loffset; 719 return; 720 } 721 if (maxclen > blksize) 722 vp->v_clen = maxclen - blksize; 723 else 724 vp->v_clen = 0; 725 if (!async && vp->v_clen == 0) { /* I/O not contiguous */ 726 vp->v_cstart = loffset + blksize; 727 bawrite(bp); 728 } else { /* Wait for rest of cluster */ 729 vp->v_cstart = loffset; 730 bdwrite(bp); 731 } 732 } else if (loffset == vp->v_cstart + vp->v_clen) { 733 /* 734 * At end of cluster, write it out if seqcount tells us we 735 * are operating sequentially, otherwise let the buf or 736 * update daemon handle it. 737 */ 738 bdwrite(bp); 739 if (seqcount > 1) 740 cluster_wbuild_wb(vp, blksize, vp->v_cstart, 741 vp->v_clen + blksize); 742 vp->v_clen = 0; 743 vp->v_cstart = loffset + blksize; 744 } else if (vm_page_count_severe()) { 745 /* 746 * We are low on memory, get it going NOW 747 */ 748 bawrite(bp); 749 } else { 750 /* 751 * In the middle of a cluster, so just delay the I/O for now. 752 */ 753 bdwrite(bp); 754 } 755 vp->v_lastw = loffset; 756 vp->v_lasta = bp->b_bio2.bio_offset; 757 } 758 759 760 /* 761 * This is an awful lot like cluster_rbuild...wish they could be combined. 762 * The last lbn argument is the current block on which I/O is being 763 * performed. Check to see that it doesn't fall in the middle of 764 * the current block (if last_bp == NULL). 765 */ 766 int 767 cluster_wbuild(struct vnode *vp, int blksize, off_t start_loffset, int bytes) 768 { 769 struct buf *bp, *tbp; 770 int i, j; 771 int totalwritten = 0; 772 int maxiosize = vmaxiosize(vp); 773 774 while (bytes > 0) { 775 /* 776 * If the buffer is not delayed-write (i.e. dirty), or it 777 * is delayed-write but either locked or inval, it cannot 778 * partake in the clustered write. 779 */ 780 tbp = findblk(vp, start_loffset, FINDBLK_NBLOCK); 781 if (tbp == NULL || 782 (tbp->b_flags & (B_LOCKED | B_INVAL | B_DELWRI)) != B_DELWRI || 783 (LIST_FIRST(&tbp->b_dep) && buf_checkwrite(tbp))) { 784 if (tbp) 785 BUF_UNLOCK(tbp); 786 start_loffset += blksize; 787 bytes -= blksize; 788 continue; 789 } 790 bremfree(tbp); 791 KKASSERT(tbp->b_cmd == BUF_CMD_DONE); 792 793 /* 794 * Extra memory in the buffer, punt on this buffer. 795 * XXX we could handle this in most cases, but we would 796 * have to push the extra memory down to after our max 797 * possible cluster size and then potentially pull it back 798 * up if the cluster was terminated prematurely--too much 799 * hassle. 800 */ 801 if (((tbp->b_flags & (B_CLUSTEROK|B_MALLOC)) != B_CLUSTEROK) || 802 (tbp->b_bcount != tbp->b_bufsize) || 803 (tbp->b_bcount != blksize) || 804 (bytes == blksize) || 805 ((bp = getpbuf(&cluster_pbuf_freecnt)) == NULL)) { 806 totalwritten += tbp->b_bufsize; 807 bawrite(tbp); 808 start_loffset += blksize; 809 bytes -= blksize; 810 continue; 811 } 812 813 /* 814 * Set up the pbuf. Track our append point with b_bcount 815 * and b_bufsize. b_bufsize is not used by the device but 816 * our caller uses it to loop clusters and we use it to 817 * detect a premature EOF on the block device. 818 */ 819 bp->b_bcount = 0; 820 bp->b_bufsize = 0; 821 bp->b_xio.xio_npages = 0; 822 bp->b_loffset = tbp->b_loffset; 823 bp->b_bio2.bio_offset = tbp->b_bio2.bio_offset; 824 825 /* 826 * We are synthesizing a buffer out of vm_page_t's, but 827 * if the block size is not page aligned then the starting 828 * address may not be either. Inherit the b_data offset 829 * from the original buffer. 830 */ 831 bp->b_data = (char *)((vm_offset_t)bp->b_data | 832 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 833 bp->b_flags &= ~B_ERROR; 834 bp->b_flags |= B_CLUSTER | B_BNOCLIP | 835 (tbp->b_flags & (B_VMIO | B_NEEDCOMMIT)); 836 bp->b_bio1.bio_caller_info1.cluster_head = NULL; 837 bp->b_bio1.bio_caller_info2.cluster_tail = NULL; 838 839 /* 840 * From this location in the file, scan forward to see 841 * if there are buffers with adjacent data that need to 842 * be written as well. 843 */ 844 for (i = 0; i < bytes; (i += blksize), (start_loffset += blksize)) { 845 if (i != 0) { /* If not the first buffer */ 846 tbp = findblk(vp, start_loffset, 847 FINDBLK_NBLOCK); 848 /* 849 * Buffer not found or could not be locked 850 * non-blocking. 851 */ 852 if (tbp == NULL) 853 break; 854 855 /* 856 * If it IS in core, but has different 857 * characteristics, then don't cluster 858 * with it. 859 */ 860 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK | 861 B_INVAL | B_DELWRI | B_NEEDCOMMIT)) 862 != (B_DELWRI | B_CLUSTEROK | 863 (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) || 864 (tbp->b_flags & B_LOCKED) || 865 (LIST_FIRST(&tbp->b_dep) && 866 buf_checkwrite(tbp)) 867 ) { 868 BUF_UNLOCK(tbp); 869 break; 870 } 871 872 /* 873 * Check that the combined cluster 874 * would make sense with regard to pages 875 * and would not be too large 876 */ 877 if ((tbp->b_bcount != blksize) || 878 ((bp->b_bio2.bio_offset + i) != 879 tbp->b_bio2.bio_offset) || 880 ((tbp->b_xio.xio_npages + bp->b_xio.xio_npages) > 881 (maxiosize / PAGE_SIZE))) { 882 BUF_UNLOCK(tbp); 883 break; 884 } 885 /* 886 * Ok, it's passed all the tests, 887 * so remove it from the free list 888 * and mark it busy. We will use it. 889 */ 890 bremfree(tbp); 891 KKASSERT(tbp->b_cmd == BUF_CMD_DONE); 892 } /* end of code for non-first buffers only */ 893 894 /* 895 * If the IO is via the VM then we do some 896 * special VM hackery (yuck). Since the buffer's 897 * block size may not be page-aligned it is possible 898 * for a page to be shared between two buffers. We 899 * have to get rid of the duplication when building 900 * the cluster. 901 */ 902 if (tbp->b_flags & B_VMIO) { 903 vm_page_t m; 904 905 if (i != 0) { /* if not first buffer */ 906 for (j = 0; j < tbp->b_xio.xio_npages; ++j) { 907 m = tbp->b_xio.xio_pages[j]; 908 if (m->flags & PG_BUSY) { 909 bqrelse(tbp); 910 goto finishcluster; 911 } 912 } 913 } 914 915 for (j = 0; j < tbp->b_xio.xio_npages; ++j) { 916 m = tbp->b_xio.xio_pages[j]; 917 vm_page_io_start(m); 918 vm_object_pip_add(m->object, 1); 919 if ((bp->b_xio.xio_npages == 0) || 920 (bp->b_xio.xio_pages[bp->b_xio.xio_npages - 1] != m)) { 921 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 922 bp->b_xio.xio_npages++; 923 } 924 } 925 } 926 bp->b_bcount += blksize; 927 bp->b_bufsize += blksize; 928 929 bundirty(tbp); 930 tbp->b_flags &= ~B_ERROR; 931 tbp->b_cmd = BUF_CMD_WRITE; 932 BUF_KERNPROC(tbp); 933 cluster_append(&bp->b_bio1, tbp); 934 935 /* 936 * check for latent dependencies to be handled 937 */ 938 if (LIST_FIRST(&tbp->b_dep) != NULL) 939 buf_start(tbp); 940 } 941 finishcluster: 942 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 943 (vm_page_t *) bp->b_xio.xio_pages, bp->b_xio.xio_npages); 944 if (bp->b_bufsize > bp->b_kvasize) { 945 panic( 946 "cluster_wbuild: b_bufsize(%d) > b_kvasize(%d)\n", 947 bp->b_bufsize, bp->b_kvasize); 948 } 949 totalwritten += bp->b_bufsize; 950 bp->b_dirtyoff = 0; 951 bp->b_dirtyend = bp->b_bufsize; 952 bp->b_bio1.bio_done = cluster_callback; 953 bp->b_cmd = BUF_CMD_WRITE; 954 955 vfs_busy_pages(vp, bp); 956 bp->b_runningbufspace = bp->b_bufsize; 957 if (bp->b_runningbufspace) { 958 runningbufspace += bp->b_runningbufspace; 959 ++runningbufcount; 960 } 961 BUF_KERNPROC(bp); 962 vn_strategy(vp, &bp->b_bio1); 963 964 bytes -= i; 965 } 966 return totalwritten; 967 } 968 969 /* 970 * Collect together all the buffers in a cluster. 971 * Plus add one additional buffer. 972 */ 973 static struct cluster_save * 974 cluster_collectbufs(struct vnode *vp, struct buf *last_bp, int blksize) 975 { 976 struct cluster_save *buflist; 977 struct buf *bp; 978 off_t loffset; 979 int i, len; 980 981 len = (int)(vp->v_lastw - vp->v_cstart + blksize) / blksize; 982 buflist = kmalloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist), 983 M_SEGMENT, M_WAITOK); 984 buflist->bs_nchildren = 0; 985 buflist->bs_children = (struct buf **) (buflist + 1); 986 for (loffset = vp->v_cstart, i = 0; i < len; (loffset += blksize), i++) { 987 (void) bread(vp, loffset, last_bp->b_bcount, &bp); 988 buflist->bs_children[i] = bp; 989 if (bp->b_bio2.bio_offset == NOOFFSET) { 990 VOP_BMAP(bp->b_vp, bp->b_loffset, 991 &bp->b_bio2.bio_offset, 992 NULL, NULL, BUF_CMD_WRITE); 993 } 994 } 995 buflist->bs_children[i] = bp = last_bp; 996 if (bp->b_bio2.bio_offset == NOOFFSET) { 997 VOP_BMAP(bp->b_vp, bp->b_loffset, &bp->b_bio2.bio_offset, 998 NULL, NULL, BUF_CMD_WRITE); 999 } 1000 buflist->bs_nchildren = i + 1; 1001 return (buflist); 1002 } 1003 1004 void 1005 cluster_append(struct bio *bio, struct buf *tbp) 1006 { 1007 tbp->b_cluster_next = NULL; 1008 if (bio->bio_caller_info1.cluster_head == NULL) { 1009 bio->bio_caller_info1.cluster_head = tbp; 1010 bio->bio_caller_info2.cluster_tail = tbp; 1011 } else { 1012 bio->bio_caller_info2.cluster_tail->b_cluster_next = tbp; 1013 bio->bio_caller_info2.cluster_tail = tbp; 1014 } 1015 } 1016 1017