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 static void cluster_setram (struct buf *); 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 * racluster - calculate maximum cluster IO size (limited by 111 * backing block device). 112 * 113 * Try to limit the amount of read-ahead by a few ad-hoc parameters. 114 * This needs work!!! 115 * 116 * NOTE! The BMAP operations may involve synchronous I/O so we 117 * really want several cluster IOs in progress to absorb 118 * the time lag. 119 */ 120 racluster = vmaxiosize(vp) / blksize; 121 maxra = 2 * racluster + (totread / blksize); 122 if (maxra > MAXRA) 123 maxra = MAXRA; 124 if (maxra > nbuf / 8) 125 maxra = nbuf / 8; 126 127 /* 128 * Get the requested block. 129 */ 130 *bpp = reqbp = bp = getblk(vp, loffset, blksize, 0, 0); 131 origoffset = loffset; 132 133 /* 134 * if it is in the cache, then check to see if the reads have been 135 * sequential. If they have, then try some read-ahead, otherwise 136 * back-off on prospective read-aheads. 137 */ 138 if (bp->b_flags & B_CACHE) { 139 /* 140 * Not sequential, do not do any read-ahead 141 */ 142 if (seqcount == 0 || maxra == 0) 143 return 0; 144 145 /* 146 * No read-ahead mark, do not do any read-ahead 147 * yet. 148 */ 149 if ((bp->b_flags & B_RAM) == 0) 150 return 0; 151 152 /* 153 * We hit a read-ahead-mark, figure out how much read-ahead 154 * to do (maxra) and where to start (loffset). 155 * 156 * Shortcut the scan. Typically the way this works is that 157 * we've built up all the blocks inbetween except for the 158 * last in previous iterations, so if the second-to-last 159 * block is present we just skip ahead to it. 160 * 161 * This algorithm has O(1) cpu in the steady state no 162 * matter how large maxra is. 163 */ 164 bp->b_flags &= ~B_RAM; 165 166 if (findblk(vp, loffset + (maxra - 2) * blksize, FINDBLK_TEST)) 167 i = maxra - 1; 168 else 169 i = 1; 170 while (i < maxra) { 171 if (findblk(vp, loffset + i * blksize, 172 FINDBLK_TEST) == NULL) { 173 break; 174 } 175 ++i; 176 } 177 if (i >= maxra) 178 return 0; 179 maxra -= i; 180 loffset += i * blksize; 181 reqbp = bp = NULL; 182 } else { 183 off_t firstread = bp->b_loffset; 184 int nblks; 185 186 /* 187 * Set-up synchronous read for bp. 188 */ 189 bp->b_cmd = BUF_CMD_READ; 190 bp->b_bio1.bio_done = biodone_sync; 191 bp->b_bio1.bio_flags |= BIO_SYNC; 192 193 KASSERT(firstread != NOOFFSET, 194 ("cluster_read: no buffer offset")); 195 if (firstread + totread > filesize) 196 totread = (int)(filesize - firstread); 197 nblks = totread / blksize; 198 if (nblks) { 199 int burstbytes; 200 201 if (nblks > racluster) 202 nblks = racluster; 203 204 error = VOP_BMAP(vp, loffset, &doffset, 205 &burstbytes, NULL, BUF_CMD_READ); 206 if (error) 207 goto single_block_read; 208 if (doffset == NOOFFSET) 209 goto single_block_read; 210 if (burstbytes < blksize * 2) 211 goto single_block_read; 212 if (nblks > burstbytes / blksize) 213 nblks = burstbytes / blksize; 214 215 bp = cluster_rbuild(vp, filesize, loffset, 216 doffset, blksize, nblks, bp); 217 loffset += bp->b_bufsize; 218 maxra -= (bp->b_bufsize - blksize) / blksize; 219 } else { 220 single_block_read: 221 /* 222 * if it isn't in the cache, then get a chunk from 223 * disk if sequential, otherwise just get the block. 224 */ 225 cluster_setram(bp); 226 loffset += blksize; 227 } 228 } 229 230 /* 231 * If B_CACHE was not set issue bp. bp will either be an 232 * asynchronous cluster buf or a synchronous single-buf. 233 * If it is a single buf it will be the same as reqbp. 234 * 235 * NOTE: Once an async cluster buf is issued bp becomes invalid. 236 */ 237 if (bp) { 238 #if defined(CLUSTERDEBUG) 239 if (rcluster) 240 kprintf("S(%lld,%d,%d) ", 241 bp->b_loffset, bp->b_bcount, seqcount); 242 #endif 243 if ((bp->b_flags & B_CLUSTER) == 0) 244 vfs_busy_pages(vp, bp); 245 bp->b_flags &= ~(B_ERROR|B_INVAL); 246 vn_strategy(vp, &bp->b_bio1); 247 error = 0; 248 /* bp invalid now */ 249 } 250 251 /* 252 * If we have been doing sequential I/O, then do some read-ahead. 253 * The code above us should have positioned us at the next likely 254 * offset. 255 * 256 * Only mess with buffers which we can immediately lock. HAMMER 257 * will do device-readahead irrespective of what the blocks 258 * represent. 259 */ 260 while (!error && seqcount && maxra > 0 && 261 loffset + blksize <= filesize) { 262 int nblksread; 263 int ntoread; 264 int burstbytes; 265 int tmp_error; 266 267 rbp = getblk(vp, loffset, blksize, 268 GETBLK_SZMATCH|GETBLK_NOWAIT, 0); 269 if (rbp == NULL) 270 goto no_read_ahead; 271 if ((rbp->b_flags & B_CACHE)) { 272 bqrelse(rbp); 273 goto no_read_ahead; 274 } 275 276 /* 277 * An error from the read-ahead bmap has nothing to do 278 * with the caller's original request. 279 */ 280 tmp_error = VOP_BMAP(vp, loffset, &doffset, 281 &burstbytes, NULL, BUF_CMD_READ); 282 if (tmp_error || doffset == NOOFFSET) { 283 rbp->b_flags |= B_INVAL; 284 brelse(rbp); 285 rbp = NULL; 286 goto no_read_ahead; 287 } 288 ntoread = burstbytes / blksize; 289 nblksread = (totread + blksize - 1) / blksize; 290 if (seqcount < nblksread) 291 seqcount = nblksread; 292 if (ntoread > seqcount) 293 ntoread = seqcount; 294 295 /* 296 * rbp: async read 297 */ 298 rbp->b_cmd = BUF_CMD_READ; 299 /*rbp->b_flags |= B_AGE*/; 300 cluster_setram(rbp); 301 302 if (burstbytes) { 303 rbp = cluster_rbuild(vp, filesize, loffset, 304 doffset, blksize, 305 ntoread, rbp); 306 } else { 307 rbp->b_bio2.bio_offset = doffset; 308 } 309 #if defined(CLUSTERDEBUG) 310 if (rcluster) { 311 if (bp) 312 kprintf("A+(%lld,%d,%lld,%d) ", 313 rbp->b_loffset, rbp->b_bcount, 314 rbp->b_loffset - origoffset, 315 seqcount); 316 else 317 kprintf("A(%lld,%d,%lld,%d) ", 318 rbp->b_loffset, rbp->b_bcount, 319 rbp->b_loffset - origoffset, 320 seqcount); 321 } 322 #endif 323 rbp->b_flags &= ~(B_ERROR|B_INVAL); 324 325 if ((rbp->b_flags & B_CLUSTER) == 0) 326 vfs_busy_pages(vp, rbp); 327 BUF_KERNPROC(rbp); 328 loffset += rbp->b_bufsize; 329 maxra -= rbp->b_bufsize / blksize; 330 vn_strategy(vp, &rbp->b_bio1); 331 /* rbp invalid now */ 332 } 333 334 /* 335 * Wait for our original buffer to complete its I/O. reqbp will 336 * be NULL if the original buffer was B_CACHE. We are returning 337 * (*bpp) which is the same as reqbp when reqbp != NULL. 338 */ 339 no_read_ahead: 340 if (reqbp) { 341 KKASSERT(reqbp->b_bio1.bio_flags & BIO_SYNC); 342 error = biowait(&reqbp->b_bio1, "clurd"); 343 } 344 return (error); 345 } 346 347 /* 348 * If blocks are contiguous on disk, use this to provide clustered 349 * read ahead. We will read as many blocks as possible sequentially 350 * and then parcel them up into logical blocks in the buffer hash table. 351 * 352 * This function either returns a cluster buf or it returns fbp. fbp is 353 * already expected to be set up as a synchronous or asynchronous request. 354 * 355 * If a cluster buf is returned it will always be async. 356 */ 357 static struct buf * 358 cluster_rbuild(struct vnode *vp, off_t filesize, off_t loffset, off_t doffset, 359 int blksize, int run, struct buf *fbp) 360 { 361 struct buf *bp, *tbp; 362 off_t boffset; 363 int i, j; 364 int maxiosize = vmaxiosize(vp); 365 366 /* 367 * avoid a division 368 */ 369 while (loffset + run * blksize > filesize) { 370 --run; 371 } 372 373 tbp = fbp; 374 tbp->b_bio2.bio_offset = doffset; 375 if((tbp->b_flags & B_MALLOC) || 376 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1)) { 377 return tbp; 378 } 379 380 bp = trypbuf(&cluster_pbuf_freecnt); 381 if (bp == NULL) { 382 return tbp; 383 } 384 385 /* 386 * We are synthesizing a buffer out of vm_page_t's, but 387 * if the block size is not page aligned then the starting 388 * address may not be either. Inherit the b_data offset 389 * from the original buffer. 390 */ 391 bp->b_data = (char *)((vm_offset_t)bp->b_data | 392 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 393 bp->b_flags |= B_CLUSTER | B_VMIO; 394 bp->b_cmd = BUF_CMD_READ; 395 bp->b_bio1.bio_done = cluster_callback; /* default to async */ 396 bp->b_bio1.bio_caller_info1.cluster_head = NULL; 397 bp->b_bio1.bio_caller_info2.cluster_tail = NULL; 398 bp->b_loffset = loffset; 399 bp->b_bio2.bio_offset = doffset; 400 KASSERT(bp->b_loffset != NOOFFSET, 401 ("cluster_rbuild: no buffer offset")); 402 403 bp->b_bcount = 0; 404 bp->b_bufsize = 0; 405 bp->b_xio.xio_npages = 0; 406 407 for (boffset = doffset, i = 0; i < run; ++i, boffset += blksize) { 408 if (i) { 409 if ((bp->b_xio.xio_npages * PAGE_SIZE) + 410 round_page(blksize) > maxiosize) { 411 break; 412 } 413 414 /* 415 * Shortcut some checks and try to avoid buffers that 416 * would block in the lock. The same checks have to 417 * be made again after we officially get the buffer. 418 */ 419 tbp = getblk(vp, loffset + i * blksize, blksize, 420 GETBLK_SZMATCH|GETBLK_NOWAIT, 0); 421 if (tbp == NULL) 422 break; 423 for (j = 0; j < tbp->b_xio.xio_npages; j++) { 424 if (tbp->b_xio.xio_pages[j]->valid) 425 break; 426 } 427 if (j != tbp->b_xio.xio_npages) { 428 bqrelse(tbp); 429 break; 430 } 431 432 /* 433 * Stop scanning if the buffer is fuly valid 434 * (marked B_CACHE), or locked (may be doing a 435 * background write), or if the buffer is not 436 * VMIO backed. The clustering code can only deal 437 * with VMIO-backed buffers. 438 */ 439 if ((tbp->b_flags & (B_CACHE|B_LOCKED)) || 440 (tbp->b_flags & B_VMIO) == 0 || 441 (LIST_FIRST(&tbp->b_dep) != NULL && 442 buf_checkread(tbp)) 443 ) { 444 bqrelse(tbp); 445 break; 446 } 447 448 /* 449 * The buffer must be completely invalid in order to 450 * take part in the cluster. If it is partially valid 451 * then we stop. 452 */ 453 for (j = 0;j < tbp->b_xio.xio_npages; j++) { 454 if (tbp->b_xio.xio_pages[j]->valid) 455 break; 456 } 457 if (j != tbp->b_xio.xio_npages) { 458 bqrelse(tbp); 459 break; 460 } 461 462 /* 463 * Set a read-ahead mark as appropriate 464 */ 465 if (i == 1 || i == (run - 1)) 466 cluster_setram(tbp); 467 468 /* 469 * Depress the priority of buffers not explicitly 470 * requested. 471 */ 472 /* tbp->b_flags |= B_AGE; */ 473 474 /* 475 * Set the block number if it isn't set, otherwise 476 * if it is make sure it matches the block number we 477 * expect. 478 */ 479 if (tbp->b_bio2.bio_offset == NOOFFSET) { 480 tbp->b_bio2.bio_offset = boffset; 481 } else if (tbp->b_bio2.bio_offset != boffset) { 482 brelse(tbp); 483 break; 484 } 485 } 486 487 /* 488 * The passed-in tbp (i == 0) will already be set up for 489 * async or sync operation. All other tbp's acquire in 490 * our loop are set up for async operation. 491 */ 492 tbp->b_cmd = BUF_CMD_READ; 493 BUF_KERNPROC(tbp); 494 cluster_append(&bp->b_bio1, tbp); 495 for (j = 0; j < tbp->b_xio.xio_npages; ++j) { 496 vm_page_t m; 497 m = tbp->b_xio.xio_pages[j]; 498 vm_page_io_start(m); 499 vm_object_pip_add(m->object, 1); 500 if ((bp->b_xio.xio_npages == 0) || 501 (bp->b_xio.xio_pages[bp->b_xio.xio_npages-1] != m)) { 502 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 503 bp->b_xio.xio_npages++; 504 } 505 if ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) 506 tbp->b_xio.xio_pages[j] = bogus_page; 507 } 508 /* 509 * XXX shouldn't this be += size for both, like in 510 * cluster_wbuild()? 511 * 512 * Don't inherit tbp->b_bufsize as it may be larger due to 513 * a non-page-aligned size. Instead just aggregate using 514 * 'size'. 515 */ 516 if (tbp->b_bcount != blksize) 517 kprintf("warning: tbp->b_bcount wrong %d vs %d\n", tbp->b_bcount, blksize); 518 if (tbp->b_bufsize != blksize) 519 kprintf("warning: tbp->b_bufsize wrong %d vs %d\n", tbp->b_bufsize, blksize); 520 bp->b_bcount += blksize; 521 bp->b_bufsize += blksize; 522 } 523 524 /* 525 * Fully valid pages in the cluster are already good and do not need 526 * to be re-read from disk. Replace the page with bogus_page 527 */ 528 for (j = 0; j < bp->b_xio.xio_npages; j++) { 529 if ((bp->b_xio.xio_pages[j]->valid & VM_PAGE_BITS_ALL) == 530 VM_PAGE_BITS_ALL) { 531 bp->b_xio.xio_pages[j] = bogus_page; 532 } 533 } 534 if (bp->b_bufsize > bp->b_kvasize) { 535 panic("cluster_rbuild: b_bufsize(%d) > b_kvasize(%d)", 536 bp->b_bufsize, bp->b_kvasize); 537 } 538 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 539 (vm_page_t *)bp->b_xio.xio_pages, bp->b_xio.xio_npages); 540 BUF_KERNPROC(bp); 541 return (bp); 542 } 543 544 /* 545 * Cleanup after a clustered read or write. 546 * This is complicated by the fact that any of the buffers might have 547 * extra memory (if there were no empty buffer headers at allocbuf time) 548 * that we will need to shift around. 549 * 550 * The returned bio is &bp->b_bio1 551 */ 552 void 553 cluster_callback(struct bio *bio) 554 { 555 struct buf *bp = bio->bio_buf; 556 struct buf *tbp; 557 int error = 0; 558 559 /* 560 * Must propogate errors to all the components. A short read (EOF) 561 * is a critical error. 562 */ 563 if (bp->b_flags & B_ERROR) { 564 error = bp->b_error; 565 } else if (bp->b_bcount != bp->b_bufsize) { 566 panic("cluster_callback: unexpected EOF on cluster %p!", bio); 567 } 568 569 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_xio.xio_npages); 570 /* 571 * Move memory from the large cluster buffer into the component 572 * buffers and mark IO as done on these. Since the memory map 573 * is the same, no actual copying is required. 574 */ 575 while ((tbp = bio->bio_caller_info1.cluster_head) != NULL) { 576 bio->bio_caller_info1.cluster_head = tbp->b_cluster_next; 577 if (error) { 578 tbp->b_flags |= B_ERROR; 579 tbp->b_error = error; 580 } else { 581 tbp->b_dirtyoff = tbp->b_dirtyend = 0; 582 tbp->b_flags &= ~(B_ERROR|B_INVAL); 583 /* 584 * XXX the bdwrite()/bqrelse() issued during 585 * cluster building clears B_RELBUF (see bqrelse() 586 * comment). If direct I/O was specified, we have 587 * to restore it here to allow the buffer and VM 588 * to be freed. 589 */ 590 if (tbp->b_flags & B_DIRECT) 591 tbp->b_flags |= B_RELBUF; 592 } 593 biodone(&tbp->b_bio1); 594 } 595 relpbuf(bp, &cluster_pbuf_freecnt); 596 } 597 598 /* 599 * cluster_wbuild_wb: 600 * 601 * Implement modified write build for cluster. 602 * 603 * write_behind = 0 write behind disabled 604 * write_behind = 1 write behind normal (default) 605 * write_behind = 2 write behind backed-off 606 */ 607 608 static __inline int 609 cluster_wbuild_wb(struct vnode *vp, int blksize, off_t start_loffset, int len) 610 { 611 int r = 0; 612 613 switch(write_behind) { 614 case 2: 615 if (start_loffset < len) 616 break; 617 start_loffset -= len; 618 /* fall through */ 619 case 1: 620 r = cluster_wbuild(vp, blksize, start_loffset, len); 621 /* fall through */ 622 default: 623 /* fall through */ 624 break; 625 } 626 return(r); 627 } 628 629 /* 630 * Do clustered write for FFS. 631 * 632 * Three cases: 633 * 1. Write is not sequential (write asynchronously) 634 * Write is sequential: 635 * 2. beginning of cluster - begin cluster 636 * 3. middle of a cluster - add to cluster 637 * 4. end of a cluster - asynchronously write cluster 638 */ 639 void 640 cluster_write(struct buf *bp, off_t filesize, int blksize, int seqcount) 641 { 642 struct vnode *vp; 643 off_t loffset; 644 int maxclen, cursize; 645 int async; 646 647 vp = bp->b_vp; 648 if (vp->v_type == VREG) 649 async = vp->v_mount->mnt_flag & MNT_ASYNC; 650 else 651 async = 0; 652 loffset = bp->b_loffset; 653 KASSERT(bp->b_loffset != NOOFFSET, 654 ("cluster_write: no buffer offset")); 655 656 /* Initialize vnode to beginning of file. */ 657 if (loffset == 0) 658 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0; 659 660 if (vp->v_clen == 0 || loffset != vp->v_lastw + blksize || 661 bp->b_bio2.bio_offset == NOOFFSET || 662 (bp->b_bio2.bio_offset != vp->v_lasta + blksize)) { 663 maxclen = vmaxiosize(vp); 664 if (vp->v_clen != 0) { 665 /* 666 * Next block is not sequential. 667 * 668 * If we are not writing at end of file, the process 669 * seeked to another point in the file since its last 670 * write, or we have reached our maximum cluster size, 671 * then push the previous cluster. Otherwise try 672 * reallocating to make it sequential. 673 * 674 * Change to algorithm: only push previous cluster if 675 * it was sequential from the point of view of the 676 * seqcount heuristic, otherwise leave the buffer 677 * intact so we can potentially optimize the I/O 678 * later on in the buf_daemon or update daemon 679 * flush. 680 */ 681 cursize = vp->v_lastw - vp->v_cstart + blksize; 682 if (bp->b_loffset + blksize != filesize || 683 loffset != vp->v_lastw + blksize || vp->v_clen <= cursize) { 684 if (!async && seqcount > 0) { 685 cluster_wbuild_wb(vp, blksize, 686 vp->v_cstart, cursize); 687 } 688 } else { 689 struct buf **bpp, **endbp; 690 struct cluster_save *buflist; 691 692 buflist = cluster_collectbufs(vp, bp, blksize); 693 endbp = &buflist->bs_children 694 [buflist->bs_nchildren - 1]; 695 if (VOP_REALLOCBLKS(vp, buflist)) { 696 /* 697 * Failed, push the previous cluster 698 * if *really* writing sequentially 699 * in the logical file (seqcount > 1), 700 * otherwise delay it in the hopes that 701 * the low level disk driver can 702 * optimize the write ordering. 703 */ 704 for (bpp = buflist->bs_children; 705 bpp < endbp; bpp++) 706 brelse(*bpp); 707 kfree(buflist, M_SEGMENT); 708 if (seqcount > 1) { 709 cluster_wbuild_wb(vp, 710 blksize, vp->v_cstart, 711 cursize); 712 } 713 } else { 714 /* 715 * Succeeded, keep building cluster. 716 */ 717 for (bpp = buflist->bs_children; 718 bpp <= endbp; bpp++) 719 bdwrite(*bpp); 720 kfree(buflist, M_SEGMENT); 721 vp->v_lastw = loffset; 722 vp->v_lasta = bp->b_bio2.bio_offset; 723 return; 724 } 725 } 726 } 727 /* 728 * Consider beginning a cluster. If at end of file, make 729 * cluster as large as possible, otherwise find size of 730 * existing cluster. 731 */ 732 if ((vp->v_type == VREG) && 733 bp->b_loffset + blksize != filesize && 734 (bp->b_bio2.bio_offset == NOOFFSET) && 735 (VOP_BMAP(vp, loffset, &bp->b_bio2.bio_offset, &maxclen, NULL, BUF_CMD_WRITE) || 736 bp->b_bio2.bio_offset == NOOFFSET)) { 737 bawrite(bp); 738 vp->v_clen = 0; 739 vp->v_lasta = bp->b_bio2.bio_offset; 740 vp->v_cstart = loffset + blksize; 741 vp->v_lastw = loffset; 742 return; 743 } 744 if (maxclen > blksize) 745 vp->v_clen = maxclen - blksize; 746 else 747 vp->v_clen = 0; 748 if (!async && vp->v_clen == 0) { /* I/O not contiguous */ 749 vp->v_cstart = loffset + blksize; 750 bawrite(bp); 751 } else { /* Wait for rest of cluster */ 752 vp->v_cstart = loffset; 753 bdwrite(bp); 754 } 755 } else if (loffset == vp->v_cstart + vp->v_clen) { 756 /* 757 * At end of cluster, write it out if seqcount tells us we 758 * are operating sequentially, otherwise let the buf or 759 * update daemon handle it. 760 */ 761 bdwrite(bp); 762 if (seqcount > 1) 763 cluster_wbuild_wb(vp, blksize, vp->v_cstart, 764 vp->v_clen + blksize); 765 vp->v_clen = 0; 766 vp->v_cstart = loffset + blksize; 767 } else if (vm_page_count_severe()) { 768 /* 769 * We are low on memory, get it going NOW 770 */ 771 bawrite(bp); 772 } else { 773 /* 774 * In the middle of a cluster, so just delay the I/O for now. 775 */ 776 bdwrite(bp); 777 } 778 vp->v_lastw = loffset; 779 vp->v_lasta = bp->b_bio2.bio_offset; 780 } 781 782 783 /* 784 * This is an awful lot like cluster_rbuild...wish they could be combined. 785 * The last lbn argument is the current block on which I/O is being 786 * performed. Check to see that it doesn't fall in the middle of 787 * the current block (if last_bp == NULL). 788 */ 789 int 790 cluster_wbuild(struct vnode *vp, int blksize, off_t start_loffset, int bytes) 791 { 792 struct buf *bp, *tbp; 793 int i, j; 794 int totalwritten = 0; 795 int maxiosize = vmaxiosize(vp); 796 797 while (bytes > 0) { 798 /* 799 * If the buffer is not delayed-write (i.e. dirty), or it 800 * is delayed-write but either locked or inval, it cannot 801 * partake in the clustered write. 802 */ 803 tbp = findblk(vp, start_loffset, FINDBLK_NBLOCK); 804 if (tbp == NULL || 805 (tbp->b_flags & (B_LOCKED | B_INVAL | B_DELWRI)) != B_DELWRI || 806 (LIST_FIRST(&tbp->b_dep) && buf_checkwrite(tbp))) { 807 if (tbp) 808 BUF_UNLOCK(tbp); 809 start_loffset += blksize; 810 bytes -= blksize; 811 continue; 812 } 813 bremfree(tbp); 814 KKASSERT(tbp->b_cmd == BUF_CMD_DONE); 815 816 /* 817 * Extra memory in the buffer, punt on this buffer. 818 * XXX we could handle this in most cases, but we would 819 * have to push the extra memory down to after our max 820 * possible cluster size and then potentially pull it back 821 * up if the cluster was terminated prematurely--too much 822 * hassle. 823 */ 824 if (((tbp->b_flags & (B_CLUSTEROK|B_MALLOC)) != B_CLUSTEROK) || 825 (tbp->b_bcount != tbp->b_bufsize) || 826 (tbp->b_bcount != blksize) || 827 (bytes == blksize) || 828 ((bp = getpbuf(&cluster_pbuf_freecnt)) == NULL)) { 829 totalwritten += tbp->b_bufsize; 830 bawrite(tbp); 831 start_loffset += blksize; 832 bytes -= blksize; 833 continue; 834 } 835 836 /* 837 * Set up the pbuf. Track our append point with b_bcount 838 * and b_bufsize. b_bufsize is not used by the device but 839 * our caller uses it to loop clusters and we use it to 840 * detect a premature EOF on the block device. 841 */ 842 bp->b_bcount = 0; 843 bp->b_bufsize = 0; 844 bp->b_xio.xio_npages = 0; 845 bp->b_loffset = tbp->b_loffset; 846 bp->b_bio2.bio_offset = tbp->b_bio2.bio_offset; 847 848 /* 849 * We are synthesizing a buffer out of vm_page_t's, but 850 * if the block size is not page aligned then the starting 851 * address may not be either. Inherit the b_data offset 852 * from the original buffer. 853 */ 854 bp->b_data = (char *)((vm_offset_t)bp->b_data | 855 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 856 bp->b_flags &= ~B_ERROR; 857 bp->b_flags |= B_CLUSTER | B_BNOCLIP | 858 (tbp->b_flags & (B_VMIO | B_NEEDCOMMIT)); 859 bp->b_bio1.bio_caller_info1.cluster_head = NULL; 860 bp->b_bio1.bio_caller_info2.cluster_tail = NULL; 861 862 /* 863 * From this location in the file, scan forward to see 864 * if there are buffers with adjacent data that need to 865 * be written as well. 866 */ 867 for (i = 0; i < bytes; (i += blksize), (start_loffset += blksize)) { 868 if (i != 0) { /* If not the first buffer */ 869 tbp = findblk(vp, start_loffset, 870 FINDBLK_NBLOCK); 871 /* 872 * Buffer not found or could not be locked 873 * non-blocking. 874 */ 875 if (tbp == NULL) 876 break; 877 878 /* 879 * If it IS in core, but has different 880 * characteristics, then don't cluster 881 * with it. 882 */ 883 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK | 884 B_INVAL | B_DELWRI | B_NEEDCOMMIT)) 885 != (B_DELWRI | B_CLUSTEROK | 886 (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) || 887 (tbp->b_flags & B_LOCKED) || 888 (LIST_FIRST(&tbp->b_dep) && 889 buf_checkwrite(tbp)) 890 ) { 891 BUF_UNLOCK(tbp); 892 break; 893 } 894 895 /* 896 * Check that the combined cluster 897 * would make sense with regard to pages 898 * and would not be too large 899 */ 900 if ((tbp->b_bcount != blksize) || 901 ((bp->b_bio2.bio_offset + i) != 902 tbp->b_bio2.bio_offset) || 903 ((tbp->b_xio.xio_npages + bp->b_xio.xio_npages) > 904 (maxiosize / PAGE_SIZE))) { 905 BUF_UNLOCK(tbp); 906 break; 907 } 908 /* 909 * Ok, it's passed all the tests, 910 * so remove it from the free list 911 * and mark it busy. We will use it. 912 */ 913 bremfree(tbp); 914 KKASSERT(tbp->b_cmd == BUF_CMD_DONE); 915 } /* end of code for non-first buffers only */ 916 917 /* 918 * If the IO is via the VM then we do some 919 * special VM hackery (yuck). Since the buffer's 920 * block size may not be page-aligned it is possible 921 * for a page to be shared between two buffers. We 922 * have to get rid of the duplication when building 923 * the cluster. 924 */ 925 if (tbp->b_flags & B_VMIO) { 926 vm_page_t m; 927 928 if (i != 0) { /* if not first buffer */ 929 for (j = 0; j < tbp->b_xio.xio_npages; ++j) { 930 m = tbp->b_xio.xio_pages[j]; 931 if (m->flags & PG_BUSY) { 932 bqrelse(tbp); 933 goto finishcluster; 934 } 935 } 936 } 937 938 for (j = 0; j < tbp->b_xio.xio_npages; ++j) { 939 m = tbp->b_xio.xio_pages[j]; 940 vm_page_io_start(m); 941 vm_object_pip_add(m->object, 1); 942 if ((bp->b_xio.xio_npages == 0) || 943 (bp->b_xio.xio_pages[bp->b_xio.xio_npages - 1] != m)) { 944 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 945 bp->b_xio.xio_npages++; 946 } 947 } 948 } 949 bp->b_bcount += blksize; 950 bp->b_bufsize += blksize; 951 952 bundirty(tbp); 953 tbp->b_flags &= ~B_ERROR; 954 tbp->b_cmd = BUF_CMD_WRITE; 955 BUF_KERNPROC(tbp); 956 cluster_append(&bp->b_bio1, tbp); 957 958 /* 959 * check for latent dependencies to be handled 960 */ 961 if (LIST_FIRST(&tbp->b_dep) != NULL) 962 buf_start(tbp); 963 } 964 finishcluster: 965 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 966 (vm_page_t *) bp->b_xio.xio_pages, bp->b_xio.xio_npages); 967 if (bp->b_bufsize > bp->b_kvasize) { 968 panic( 969 "cluster_wbuild: b_bufsize(%d) > b_kvasize(%d)\n", 970 bp->b_bufsize, bp->b_kvasize); 971 } 972 totalwritten += bp->b_bufsize; 973 bp->b_dirtyoff = 0; 974 bp->b_dirtyend = bp->b_bufsize; 975 bp->b_bio1.bio_done = cluster_callback; 976 bp->b_cmd = BUF_CMD_WRITE; 977 978 vfs_busy_pages(vp, bp); 979 bp->b_runningbufspace = bp->b_bufsize; 980 if (bp->b_runningbufspace) { 981 runningbufspace += bp->b_runningbufspace; 982 ++runningbufcount; 983 } 984 BUF_KERNPROC(bp); 985 vn_strategy(vp, &bp->b_bio1); 986 987 bytes -= i; 988 } 989 return totalwritten; 990 } 991 992 /* 993 * Collect together all the buffers in a cluster. 994 * Plus add one additional buffer. 995 */ 996 static struct cluster_save * 997 cluster_collectbufs(struct vnode *vp, struct buf *last_bp, int blksize) 998 { 999 struct cluster_save *buflist; 1000 struct buf *bp; 1001 off_t loffset; 1002 int i, len; 1003 1004 len = (int)(vp->v_lastw - vp->v_cstart + blksize) / blksize; 1005 buflist = kmalloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist), 1006 M_SEGMENT, M_WAITOK); 1007 buflist->bs_nchildren = 0; 1008 buflist->bs_children = (struct buf **) (buflist + 1); 1009 for (loffset = vp->v_cstart, i = 0; i < len; (loffset += blksize), i++) { 1010 (void) bread(vp, loffset, last_bp->b_bcount, &bp); 1011 buflist->bs_children[i] = bp; 1012 if (bp->b_bio2.bio_offset == NOOFFSET) { 1013 VOP_BMAP(bp->b_vp, bp->b_loffset, 1014 &bp->b_bio2.bio_offset, 1015 NULL, NULL, BUF_CMD_WRITE); 1016 } 1017 } 1018 buflist->bs_children[i] = bp = last_bp; 1019 if (bp->b_bio2.bio_offset == NOOFFSET) { 1020 VOP_BMAP(bp->b_vp, bp->b_loffset, &bp->b_bio2.bio_offset, 1021 NULL, NULL, BUF_CMD_WRITE); 1022 } 1023 buflist->bs_nchildren = i + 1; 1024 return (buflist); 1025 } 1026 1027 void 1028 cluster_append(struct bio *bio, struct buf *tbp) 1029 { 1030 tbp->b_cluster_next = NULL; 1031 if (bio->bio_caller_info1.cluster_head == NULL) { 1032 bio->bio_caller_info1.cluster_head = tbp; 1033 bio->bio_caller_info2.cluster_tail = tbp; 1034 } else { 1035 bio->bio_caller_info2.cluster_tail->b_cluster_next = tbp; 1036 bio->bio_caller_info2.cluster_tail = tbp; 1037 } 1038 } 1039 1040 static 1041 void 1042 cluster_setram (struct buf *bp) 1043 { 1044 bp->b_flags |= B_RAM; 1045 if (bp->b_xio.xio_npages) 1046 vm_page_flag_set(bp->b_xio.xio_pages[0], PG_RAM); 1047 } 1048