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 seqcount -= (bp->b_bufsize + BKVASIZE - 1) / BKVASIZE; 143 if (seqcount <= 0 || maxra == 0) 144 return 0; 145 146 /* 147 * No read-ahead mark, do not do any read-ahead 148 * yet. 149 */ 150 if ((bp->b_flags & B_RAM) == 0) 151 return 0; 152 153 /* 154 * We hit a read-ahead-mark, figure out how much read-ahead 155 * to do (maxra) and where to start (loffset). 156 * 157 * Shortcut the scan. Typically the way this works is that 158 * we've built up all the blocks inbetween except for the 159 * last in previous iterations, so if the second-to-last 160 * block is present we just skip ahead to it. 161 * 162 * This algorithm has O(1) cpu in the steady state no 163 * matter how large maxra is. 164 */ 165 bp->b_flags &= ~B_RAM; 166 167 if (findblk(vp, loffset + (maxra - 2) * blksize, FINDBLK_TEST)) 168 i = maxra - 1; 169 else 170 i = 1; 171 while (i < maxra) { 172 if (findblk(vp, loffset + i * blksize, 173 FINDBLK_TEST) == NULL) { 174 break; 175 } 176 ++i; 177 } 178 if (i >= maxra) 179 return 0; 180 maxra -= i; 181 loffset += i * blksize; 182 reqbp = bp = NULL; 183 } else { 184 off_t firstread = bp->b_loffset; 185 int nblks; 186 187 /* 188 * Set-up synchronous read for bp. 189 */ 190 bp->b_cmd = BUF_CMD_READ; 191 bp->b_bio1.bio_done = biodone_sync; 192 bp->b_bio1.bio_flags |= BIO_SYNC; 193 194 KASSERT(firstread != NOOFFSET, 195 ("cluster_read: no buffer offset")); 196 if (firstread + totread > filesize) 197 totread = (int)(filesize - firstread); 198 nblks = totread / blksize; 199 if (nblks) { 200 int burstbytes; 201 202 if (nblks > racluster) 203 nblks = racluster; 204 205 error = VOP_BMAP(vp, loffset, &doffset, 206 &burstbytes, NULL, BUF_CMD_READ); 207 if (error) 208 goto single_block_read; 209 if (doffset == NOOFFSET) 210 goto single_block_read; 211 if (burstbytes < blksize * 2) 212 goto single_block_read; 213 if (nblks > burstbytes / blksize) 214 nblks = burstbytes / blksize; 215 216 bp = cluster_rbuild(vp, filesize, loffset, 217 doffset, blksize, nblks, bp); 218 loffset += bp->b_bufsize; 219 maxra -= (bp->b_bufsize - blksize) / blksize; 220 } else { 221 single_block_read: 222 /* 223 * if it isn't in the cache, then get a chunk from 224 * disk if sequential, otherwise just get the block. 225 */ 226 cluster_setram(bp); 227 loffset += blksize; 228 } 229 } 230 231 /* 232 * If B_CACHE was not set issue bp. bp will either be an 233 * asynchronous cluster buf or a synchronous single-buf. 234 * If it is a single buf it will be the same as reqbp. 235 * 236 * NOTE: Once an async cluster buf is issued bp becomes invalid. 237 */ 238 if (bp) { 239 #if defined(CLUSTERDEBUG) 240 if (rcluster) 241 kprintf("S(%lld,%d,%d)\n", 242 bp->b_loffset, bp->b_bcount, seqcount); 243 #endif 244 if ((bp->b_flags & B_CLUSTER) == 0) 245 vfs_busy_pages(vp, bp); 246 bp->b_flags &= ~(B_ERROR|B_INVAL); 247 seqcount -= (bp->b_bufsize + BKVASIZE - 1) / BKVASIZE; 248 vn_strategy(vp, &bp->b_bio1); 249 error = 0; 250 /* bp invalid now */ 251 } 252 253 /* 254 * If we have been doing sequential I/O, then do some read-ahead. 255 * The code above us should have positioned us at the next likely 256 * offset. 257 * 258 * Only mess with buffers which we can immediately lock. HAMMER 259 * will do device-readahead irrespective of what the blocks 260 * represent. 261 */ 262 while (!error && seqcount > 0 && maxra > 0 && 263 loffset + blksize <= filesize) { 264 int nblksread; 265 int ntoread; 266 int burstbytes; 267 int tmp_error; 268 269 rbp = getblk(vp, loffset, blksize, 270 GETBLK_SZMATCH|GETBLK_NOWAIT, 0); 271 if (rbp == NULL) 272 goto no_read_ahead; 273 if ((rbp->b_flags & B_CACHE)) { 274 bqrelse(rbp); 275 goto no_read_ahead; 276 } 277 278 /* 279 * An error from the read-ahead bmap has nothing to do 280 * with the caller's original request. 281 */ 282 tmp_error = VOP_BMAP(vp, loffset, &doffset, 283 &burstbytes, NULL, BUF_CMD_READ); 284 if (tmp_error || doffset == NOOFFSET) { 285 rbp->b_flags |= B_INVAL; 286 brelse(rbp); 287 rbp = NULL; 288 goto no_read_ahead; 289 } 290 ntoread = burstbytes / blksize; 291 nblksread = (totread + blksize - 1) / blksize; 292 if (seqcount < nblksread) 293 seqcount = nblksread; 294 if (ntoread > seqcount) 295 ntoread = seqcount; 296 297 /* 298 * rbp: async read 299 */ 300 rbp->b_cmd = BUF_CMD_READ; 301 /*rbp->b_flags |= B_AGE*/; 302 cluster_setram(rbp); 303 304 if (burstbytes) { 305 rbp = cluster_rbuild(vp, filesize, loffset, 306 doffset, blksize, 307 ntoread, rbp); 308 } else { 309 rbp->b_bio2.bio_offset = doffset; 310 } 311 seqcount -= (rbp->b_bufsize + BKVASIZE - 1) / BKVASIZE; 312 #if defined(CLUSTERDEBUG) 313 if (rcluster) { 314 if (bp) 315 kprintf("A+(%lld,%d,%lld,%d) ra=%d\n", 316 rbp->b_loffset, rbp->b_bcount, 317 rbp->b_loffset - origoffset, 318 seqcount, maxra); 319 else 320 kprintf("A-(%lld,%d,%lld,%d) ra=%d\n", 321 rbp->b_loffset, rbp->b_bcount, 322 rbp->b_loffset - origoffset, 323 seqcount, maxra); 324 } 325 #endif 326 rbp->b_flags &= ~(B_ERROR|B_INVAL); 327 328 if ((rbp->b_flags & B_CLUSTER) == 0) 329 vfs_busy_pages(vp, rbp); 330 BUF_KERNPROC(rbp); 331 loffset += rbp->b_bufsize; 332 maxra -= rbp->b_bufsize / blksize; 333 vn_strategy(vp, &rbp->b_bio1); 334 /* rbp invalid now */ 335 } 336 337 /* 338 * Wait for our original buffer to complete its I/O. reqbp will 339 * be NULL if the original buffer was B_CACHE. We are returning 340 * (*bpp) which is the same as reqbp when reqbp != NULL. 341 */ 342 no_read_ahead: 343 if (reqbp) { 344 KKASSERT(reqbp->b_bio1.bio_flags & BIO_SYNC); 345 error = biowait(&reqbp->b_bio1, "clurd"); 346 } 347 return (error); 348 } 349 350 /* 351 * If blocks are contiguous on disk, use this to provide clustered 352 * read ahead. We will read as many blocks as possible sequentially 353 * and then parcel them up into logical blocks in the buffer hash table. 354 * 355 * This function either returns a cluster buf or it returns fbp. fbp is 356 * already expected to be set up as a synchronous or asynchronous request. 357 * 358 * If a cluster buf is returned it will always be async. 359 */ 360 static struct buf * 361 cluster_rbuild(struct vnode *vp, off_t filesize, off_t loffset, off_t doffset, 362 int blksize, int run, struct buf *fbp) 363 { 364 struct buf *bp, *tbp; 365 off_t boffset; 366 int i, j; 367 int maxiosize = vmaxiosize(vp); 368 369 /* 370 * avoid a division 371 */ 372 while (loffset + run * blksize > filesize) { 373 --run; 374 } 375 376 tbp = fbp; 377 tbp->b_bio2.bio_offset = doffset; 378 if((tbp->b_flags & B_MALLOC) || 379 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1)) { 380 return tbp; 381 } 382 383 bp = trypbuf(&cluster_pbuf_freecnt); 384 if (bp == NULL) { 385 return tbp; 386 } 387 388 /* 389 * We are synthesizing a buffer out of vm_page_t's, but 390 * if the block size is not page aligned then the starting 391 * address may not be either. Inherit the b_data offset 392 * from the original buffer. 393 */ 394 bp->b_data = (char *)((vm_offset_t)bp->b_data | 395 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 396 bp->b_flags |= B_CLUSTER | B_VMIO; 397 bp->b_cmd = BUF_CMD_READ; 398 bp->b_bio1.bio_done = cluster_callback; /* default to async */ 399 bp->b_bio1.bio_caller_info1.cluster_head = NULL; 400 bp->b_bio1.bio_caller_info2.cluster_tail = NULL; 401 bp->b_loffset = loffset; 402 bp->b_bio2.bio_offset = doffset; 403 KASSERT(bp->b_loffset != NOOFFSET, 404 ("cluster_rbuild: no buffer offset")); 405 406 bp->b_bcount = 0; 407 bp->b_bufsize = 0; 408 bp->b_xio.xio_npages = 0; 409 410 for (boffset = doffset, i = 0; i < run; ++i, boffset += blksize) { 411 if (i) { 412 if ((bp->b_xio.xio_npages * PAGE_SIZE) + 413 round_page(blksize) > maxiosize) { 414 break; 415 } 416 417 /* 418 * Shortcut some checks and try to avoid buffers that 419 * would block in the lock. The same checks have to 420 * be made again after we officially get the buffer. 421 */ 422 tbp = getblk(vp, loffset + i * blksize, blksize, 423 GETBLK_SZMATCH|GETBLK_NOWAIT, 0); 424 if (tbp == NULL) 425 break; 426 for (j = 0; j < tbp->b_xio.xio_npages; j++) { 427 if (tbp->b_xio.xio_pages[j]->valid) 428 break; 429 } 430 if (j != tbp->b_xio.xio_npages) { 431 bqrelse(tbp); 432 break; 433 } 434 435 /* 436 * Stop scanning if the buffer is fuly valid 437 * (marked B_CACHE), or locked (may be doing a 438 * background write), or if the buffer is not 439 * VMIO backed. The clustering code can only deal 440 * with VMIO-backed buffers. 441 */ 442 if ((tbp->b_flags & (B_CACHE|B_LOCKED)) || 443 (tbp->b_flags & B_VMIO) == 0 || 444 (LIST_FIRST(&tbp->b_dep) != NULL && 445 buf_checkread(tbp)) 446 ) { 447 bqrelse(tbp); 448 break; 449 } 450 451 /* 452 * The buffer must be completely invalid in order to 453 * take part in the cluster. If it is partially valid 454 * then we stop. 455 */ 456 for (j = 0;j < tbp->b_xio.xio_npages; j++) { 457 if (tbp->b_xio.xio_pages[j]->valid) 458 break; 459 } 460 if (j != tbp->b_xio.xio_npages) { 461 bqrelse(tbp); 462 break; 463 } 464 465 /* 466 * Set a read-ahead mark as appropriate 467 */ 468 if (i == 1 || i == (run - 1)) 469 cluster_setram(tbp); 470 471 /* 472 * Depress the priority of buffers not explicitly 473 * requested. 474 */ 475 /* tbp->b_flags |= B_AGE; */ 476 477 /* 478 * Set the block number if it isn't set, otherwise 479 * if it is make sure it matches the block number we 480 * expect. 481 */ 482 if (tbp->b_bio2.bio_offset == NOOFFSET) { 483 tbp->b_bio2.bio_offset = boffset; 484 } else if (tbp->b_bio2.bio_offset != boffset) { 485 brelse(tbp); 486 break; 487 } 488 } 489 490 /* 491 * The passed-in tbp (i == 0) will already be set up for 492 * async or sync operation. All other tbp's acquire in 493 * our loop are set up for async operation. 494 */ 495 tbp->b_cmd = BUF_CMD_READ; 496 BUF_KERNPROC(tbp); 497 cluster_append(&bp->b_bio1, tbp); 498 for (j = 0; j < tbp->b_xio.xio_npages; ++j) { 499 vm_page_t m; 500 m = tbp->b_xio.xio_pages[j]; 501 vm_page_io_start(m); 502 vm_object_pip_add(m->object, 1); 503 if ((bp->b_xio.xio_npages == 0) || 504 (bp->b_xio.xio_pages[bp->b_xio.xio_npages-1] != m)) { 505 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 506 bp->b_xio.xio_npages++; 507 } 508 if ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) 509 tbp->b_xio.xio_pages[j] = bogus_page; 510 } 511 /* 512 * XXX shouldn't this be += size for both, like in 513 * cluster_wbuild()? 514 * 515 * Don't inherit tbp->b_bufsize as it may be larger due to 516 * a non-page-aligned size. Instead just aggregate using 517 * 'size'. 518 */ 519 if (tbp->b_bcount != blksize) 520 kprintf("warning: tbp->b_bcount wrong %d vs %d\n", tbp->b_bcount, blksize); 521 if (tbp->b_bufsize != blksize) 522 kprintf("warning: tbp->b_bufsize wrong %d vs %d\n", tbp->b_bufsize, blksize); 523 bp->b_bcount += blksize; 524 bp->b_bufsize += blksize; 525 } 526 527 /* 528 * Fully valid pages in the cluster are already good and do not need 529 * to be re-read from disk. Replace the page with bogus_page 530 */ 531 for (j = 0; j < bp->b_xio.xio_npages; j++) { 532 if ((bp->b_xio.xio_pages[j]->valid & VM_PAGE_BITS_ALL) == 533 VM_PAGE_BITS_ALL) { 534 bp->b_xio.xio_pages[j] = bogus_page; 535 } 536 } 537 if (bp->b_bufsize > bp->b_kvasize) { 538 panic("cluster_rbuild: b_bufsize(%d) > b_kvasize(%d)", 539 bp->b_bufsize, bp->b_kvasize); 540 } 541 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 542 (vm_page_t *)bp->b_xio.xio_pages, bp->b_xio.xio_npages); 543 BUF_KERNPROC(bp); 544 return (bp); 545 } 546 547 /* 548 * Cleanup after a clustered read or write. 549 * This is complicated by the fact that any of the buffers might have 550 * extra memory (if there were no empty buffer headers at allocbuf time) 551 * that we will need to shift around. 552 * 553 * The returned bio is &bp->b_bio1 554 */ 555 void 556 cluster_callback(struct bio *bio) 557 { 558 struct buf *bp = bio->bio_buf; 559 struct buf *tbp; 560 int error = 0; 561 562 /* 563 * Must propogate errors to all the components. A short read (EOF) 564 * is a critical error. 565 */ 566 if (bp->b_flags & B_ERROR) { 567 error = bp->b_error; 568 } else if (bp->b_bcount != bp->b_bufsize) { 569 panic("cluster_callback: unexpected EOF on cluster %p!", bio); 570 } 571 572 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_xio.xio_npages); 573 /* 574 * Move memory from the large cluster buffer into the component 575 * buffers and mark IO as done on these. Since the memory map 576 * is the same, no actual copying is required. 577 */ 578 while ((tbp = bio->bio_caller_info1.cluster_head) != NULL) { 579 bio->bio_caller_info1.cluster_head = tbp->b_cluster_next; 580 if (error) { 581 tbp->b_flags |= B_ERROR; 582 tbp->b_error = error; 583 } else { 584 tbp->b_dirtyoff = tbp->b_dirtyend = 0; 585 tbp->b_flags &= ~(B_ERROR|B_INVAL); 586 /* 587 * XXX the bdwrite()/bqrelse() issued during 588 * cluster building clears B_RELBUF (see bqrelse() 589 * comment). If direct I/O was specified, we have 590 * to restore it here to allow the buffer and VM 591 * to be freed. 592 */ 593 if (tbp->b_flags & B_DIRECT) 594 tbp->b_flags |= B_RELBUF; 595 } 596 biodone(&tbp->b_bio1); 597 } 598 relpbuf(bp, &cluster_pbuf_freecnt); 599 } 600 601 /* 602 * cluster_wbuild_wb: 603 * 604 * Implement modified write build for cluster. 605 * 606 * write_behind = 0 write behind disabled 607 * write_behind = 1 write behind normal (default) 608 * write_behind = 2 write behind backed-off 609 */ 610 611 static __inline int 612 cluster_wbuild_wb(struct vnode *vp, int blksize, off_t start_loffset, int len) 613 { 614 int r = 0; 615 616 switch(write_behind) { 617 case 2: 618 if (start_loffset < len) 619 break; 620 start_loffset -= len; 621 /* fall through */ 622 case 1: 623 r = cluster_wbuild(vp, blksize, start_loffset, len); 624 /* fall through */ 625 default: 626 /* fall through */ 627 break; 628 } 629 return(r); 630 } 631 632 /* 633 * Do clustered write for FFS. 634 * 635 * Three cases: 636 * 1. Write is not sequential (write asynchronously) 637 * Write is sequential: 638 * 2. beginning of cluster - begin cluster 639 * 3. middle of a cluster - add to cluster 640 * 4. end of a cluster - asynchronously write cluster 641 */ 642 void 643 cluster_write(struct buf *bp, off_t filesize, int blksize, int seqcount) 644 { 645 struct vnode *vp; 646 off_t loffset; 647 int maxclen, cursize; 648 int async; 649 650 vp = bp->b_vp; 651 if (vp->v_type == VREG) 652 async = vp->v_mount->mnt_flag & MNT_ASYNC; 653 else 654 async = 0; 655 loffset = bp->b_loffset; 656 KASSERT(bp->b_loffset != NOOFFSET, 657 ("cluster_write: no buffer offset")); 658 659 /* Initialize vnode to beginning of file. */ 660 if (loffset == 0) 661 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0; 662 663 if (vp->v_clen == 0 || loffset != vp->v_lastw + blksize || 664 bp->b_bio2.bio_offset == NOOFFSET || 665 (bp->b_bio2.bio_offset != vp->v_lasta + blksize)) { 666 maxclen = vmaxiosize(vp); 667 if (vp->v_clen != 0) { 668 /* 669 * Next block is not sequential. 670 * 671 * If we are not writing at end of file, the process 672 * seeked to another point in the file since its last 673 * write, or we have reached our maximum cluster size, 674 * then push the previous cluster. Otherwise try 675 * reallocating to make it sequential. 676 * 677 * Change to algorithm: only push previous cluster if 678 * it was sequential from the point of view of the 679 * seqcount heuristic, otherwise leave the buffer 680 * intact so we can potentially optimize the I/O 681 * later on in the buf_daemon or update daemon 682 * flush. 683 */ 684 cursize = vp->v_lastw - vp->v_cstart + blksize; 685 if (bp->b_loffset + blksize != filesize || 686 loffset != vp->v_lastw + blksize || vp->v_clen <= cursize) { 687 if (!async && seqcount > 0) { 688 cluster_wbuild_wb(vp, blksize, 689 vp->v_cstart, cursize); 690 } 691 } else { 692 struct buf **bpp, **endbp; 693 struct cluster_save *buflist; 694 695 buflist = cluster_collectbufs(vp, bp, blksize); 696 endbp = &buflist->bs_children 697 [buflist->bs_nchildren - 1]; 698 if (VOP_REALLOCBLKS(vp, buflist)) { 699 /* 700 * Failed, push the previous cluster 701 * if *really* writing sequentially 702 * in the logical file (seqcount > 1), 703 * otherwise delay it in the hopes that 704 * the low level disk driver can 705 * optimize the write ordering. 706 */ 707 for (bpp = buflist->bs_children; 708 bpp < endbp; bpp++) 709 brelse(*bpp); 710 kfree(buflist, M_SEGMENT); 711 if (seqcount > 1) { 712 cluster_wbuild_wb(vp, 713 blksize, vp->v_cstart, 714 cursize); 715 } 716 } else { 717 /* 718 * Succeeded, keep building cluster. 719 */ 720 for (bpp = buflist->bs_children; 721 bpp <= endbp; bpp++) 722 bdwrite(*bpp); 723 kfree(buflist, M_SEGMENT); 724 vp->v_lastw = loffset; 725 vp->v_lasta = bp->b_bio2.bio_offset; 726 return; 727 } 728 } 729 } 730 /* 731 * Consider beginning a cluster. If at end of file, make 732 * cluster as large as possible, otherwise find size of 733 * existing cluster. 734 */ 735 if ((vp->v_type == VREG) && 736 bp->b_loffset + blksize != filesize && 737 (bp->b_bio2.bio_offset == NOOFFSET) && 738 (VOP_BMAP(vp, loffset, &bp->b_bio2.bio_offset, &maxclen, NULL, BUF_CMD_WRITE) || 739 bp->b_bio2.bio_offset == NOOFFSET)) { 740 bawrite(bp); 741 vp->v_clen = 0; 742 vp->v_lasta = bp->b_bio2.bio_offset; 743 vp->v_cstart = loffset + blksize; 744 vp->v_lastw = loffset; 745 return; 746 } 747 if (maxclen > blksize) 748 vp->v_clen = maxclen - blksize; 749 else 750 vp->v_clen = 0; 751 if (!async && vp->v_clen == 0) { /* I/O not contiguous */ 752 vp->v_cstart = loffset + blksize; 753 bawrite(bp); 754 } else { /* Wait for rest of cluster */ 755 vp->v_cstart = loffset; 756 bdwrite(bp); 757 } 758 } else if (loffset == vp->v_cstart + vp->v_clen) { 759 /* 760 * At end of cluster, write it out if seqcount tells us we 761 * are operating sequentially, otherwise let the buf or 762 * update daemon handle it. 763 */ 764 bdwrite(bp); 765 if (seqcount > 1) 766 cluster_wbuild_wb(vp, blksize, vp->v_cstart, 767 vp->v_clen + blksize); 768 vp->v_clen = 0; 769 vp->v_cstart = loffset + blksize; 770 } else if (vm_page_count_severe()) { 771 /* 772 * We are low on memory, get it going NOW 773 */ 774 bawrite(bp); 775 } else { 776 /* 777 * In the middle of a cluster, so just delay the I/O for now. 778 */ 779 bdwrite(bp); 780 } 781 vp->v_lastw = loffset; 782 vp->v_lasta = bp->b_bio2.bio_offset; 783 } 784 785 786 /* 787 * This is an awful lot like cluster_rbuild...wish they could be combined. 788 * The last lbn argument is the current block on which I/O is being 789 * performed. Check to see that it doesn't fall in the middle of 790 * the current block (if last_bp == NULL). 791 */ 792 int 793 cluster_wbuild(struct vnode *vp, int blksize, off_t start_loffset, int bytes) 794 { 795 struct buf *bp, *tbp; 796 int i, j; 797 int totalwritten = 0; 798 int maxiosize = vmaxiosize(vp); 799 800 while (bytes > 0) { 801 /* 802 * If the buffer is not delayed-write (i.e. dirty), or it 803 * is delayed-write but either locked or inval, it cannot 804 * partake in the clustered write. 805 */ 806 tbp = findblk(vp, start_loffset, FINDBLK_NBLOCK); 807 if (tbp == NULL || 808 (tbp->b_flags & (B_LOCKED | B_INVAL | B_DELWRI)) != B_DELWRI || 809 (LIST_FIRST(&tbp->b_dep) && buf_checkwrite(tbp))) { 810 if (tbp) 811 BUF_UNLOCK(tbp); 812 start_loffset += blksize; 813 bytes -= blksize; 814 continue; 815 } 816 bremfree(tbp); 817 KKASSERT(tbp->b_cmd == BUF_CMD_DONE); 818 819 /* 820 * Extra memory in the buffer, punt on this buffer. 821 * XXX we could handle this in most cases, but we would 822 * have to push the extra memory down to after our max 823 * possible cluster size and then potentially pull it back 824 * up if the cluster was terminated prematurely--too much 825 * hassle. 826 */ 827 if (((tbp->b_flags & (B_CLUSTEROK|B_MALLOC)) != B_CLUSTEROK) || 828 (tbp->b_bcount != tbp->b_bufsize) || 829 (tbp->b_bcount != blksize) || 830 (bytes == blksize) || 831 ((bp = getpbuf(&cluster_pbuf_freecnt)) == NULL)) { 832 totalwritten += tbp->b_bufsize; 833 bawrite(tbp); 834 start_loffset += blksize; 835 bytes -= blksize; 836 continue; 837 } 838 839 /* 840 * Set up the pbuf. Track our append point with b_bcount 841 * and b_bufsize. b_bufsize is not used by the device but 842 * our caller uses it to loop clusters and we use it to 843 * detect a premature EOF on the block device. 844 */ 845 bp->b_bcount = 0; 846 bp->b_bufsize = 0; 847 bp->b_xio.xio_npages = 0; 848 bp->b_loffset = tbp->b_loffset; 849 bp->b_bio2.bio_offset = tbp->b_bio2.bio_offset; 850 851 /* 852 * We are synthesizing a buffer out of vm_page_t's, but 853 * if the block size is not page aligned then the starting 854 * address may not be either. Inherit the b_data offset 855 * from the original buffer. 856 */ 857 bp->b_data = (char *)((vm_offset_t)bp->b_data | 858 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 859 bp->b_flags &= ~B_ERROR; 860 bp->b_flags |= B_CLUSTER | B_BNOCLIP | 861 (tbp->b_flags & (B_VMIO | B_NEEDCOMMIT)); 862 bp->b_bio1.bio_caller_info1.cluster_head = NULL; 863 bp->b_bio1.bio_caller_info2.cluster_tail = NULL; 864 865 /* 866 * From this location in the file, scan forward to see 867 * if there are buffers with adjacent data that need to 868 * be written as well. 869 */ 870 for (i = 0; i < bytes; (i += blksize), (start_loffset += blksize)) { 871 if (i != 0) { /* If not the first buffer */ 872 tbp = findblk(vp, start_loffset, 873 FINDBLK_NBLOCK); 874 /* 875 * Buffer not found or could not be locked 876 * non-blocking. 877 */ 878 if (tbp == NULL) 879 break; 880 881 /* 882 * If it IS in core, but has different 883 * characteristics, then don't cluster 884 * with it. 885 */ 886 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK | 887 B_INVAL | B_DELWRI | B_NEEDCOMMIT)) 888 != (B_DELWRI | B_CLUSTEROK | 889 (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) || 890 (tbp->b_flags & B_LOCKED) || 891 (LIST_FIRST(&tbp->b_dep) && 892 buf_checkwrite(tbp)) 893 ) { 894 BUF_UNLOCK(tbp); 895 break; 896 } 897 898 /* 899 * Check that the combined cluster 900 * would make sense with regard to pages 901 * and would not be too large 902 */ 903 if ((tbp->b_bcount != blksize) || 904 ((bp->b_bio2.bio_offset + i) != 905 tbp->b_bio2.bio_offset) || 906 ((tbp->b_xio.xio_npages + bp->b_xio.xio_npages) > 907 (maxiosize / PAGE_SIZE))) { 908 BUF_UNLOCK(tbp); 909 break; 910 } 911 /* 912 * Ok, it's passed all the tests, 913 * so remove it from the free list 914 * and mark it busy. We will use it. 915 */ 916 bremfree(tbp); 917 KKASSERT(tbp->b_cmd == BUF_CMD_DONE); 918 } /* end of code for non-first buffers only */ 919 920 /* 921 * If the IO is via the VM then we do some 922 * special VM hackery (yuck). Since the buffer's 923 * block size may not be page-aligned it is possible 924 * for a page to be shared between two buffers. We 925 * have to get rid of the duplication when building 926 * the cluster. 927 */ 928 if (tbp->b_flags & B_VMIO) { 929 vm_page_t m; 930 931 if (i != 0) { /* if not first buffer */ 932 for (j = 0; j < tbp->b_xio.xio_npages; ++j) { 933 m = tbp->b_xio.xio_pages[j]; 934 if (m->flags & PG_BUSY) { 935 bqrelse(tbp); 936 goto finishcluster; 937 } 938 } 939 } 940 941 for (j = 0; j < tbp->b_xio.xio_npages; ++j) { 942 m = tbp->b_xio.xio_pages[j]; 943 vm_page_io_start(m); 944 vm_object_pip_add(m->object, 1); 945 if ((bp->b_xio.xio_npages == 0) || 946 (bp->b_xio.xio_pages[bp->b_xio.xio_npages - 1] != m)) { 947 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 948 bp->b_xio.xio_npages++; 949 } 950 } 951 } 952 bp->b_bcount += blksize; 953 bp->b_bufsize += blksize; 954 955 bundirty(tbp); 956 tbp->b_flags &= ~B_ERROR; 957 tbp->b_cmd = BUF_CMD_WRITE; 958 BUF_KERNPROC(tbp); 959 cluster_append(&bp->b_bio1, tbp); 960 961 /* 962 * check for latent dependencies to be handled 963 */ 964 if (LIST_FIRST(&tbp->b_dep) != NULL) 965 buf_start(tbp); 966 } 967 finishcluster: 968 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 969 (vm_page_t *) bp->b_xio.xio_pages, bp->b_xio.xio_npages); 970 if (bp->b_bufsize > bp->b_kvasize) { 971 panic( 972 "cluster_wbuild: b_bufsize(%d) > b_kvasize(%d)\n", 973 bp->b_bufsize, bp->b_kvasize); 974 } 975 totalwritten += bp->b_bufsize; 976 bp->b_dirtyoff = 0; 977 bp->b_dirtyend = bp->b_bufsize; 978 bp->b_bio1.bio_done = cluster_callback; 979 bp->b_cmd = BUF_CMD_WRITE; 980 981 vfs_busy_pages(vp, bp); 982 bp->b_runningbufspace = bp->b_bufsize; 983 if (bp->b_runningbufspace) { 984 runningbufspace += bp->b_runningbufspace; 985 ++runningbufcount; 986 } 987 BUF_KERNPROC(bp); 988 vn_strategy(vp, &bp->b_bio1); 989 990 bytes -= i; 991 } 992 return totalwritten; 993 } 994 995 /* 996 * Collect together all the buffers in a cluster. 997 * Plus add one additional buffer. 998 */ 999 static struct cluster_save * 1000 cluster_collectbufs(struct vnode *vp, struct buf *last_bp, int blksize) 1001 { 1002 struct cluster_save *buflist; 1003 struct buf *bp; 1004 off_t loffset; 1005 int i, len; 1006 1007 len = (int)(vp->v_lastw - vp->v_cstart + blksize) / blksize; 1008 buflist = kmalloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist), 1009 M_SEGMENT, M_WAITOK); 1010 buflist->bs_nchildren = 0; 1011 buflist->bs_children = (struct buf **) (buflist + 1); 1012 for (loffset = vp->v_cstart, i = 0; i < len; (loffset += blksize), i++) { 1013 (void) bread(vp, loffset, last_bp->b_bcount, &bp); 1014 buflist->bs_children[i] = bp; 1015 if (bp->b_bio2.bio_offset == NOOFFSET) { 1016 VOP_BMAP(bp->b_vp, bp->b_loffset, 1017 &bp->b_bio2.bio_offset, 1018 NULL, NULL, BUF_CMD_WRITE); 1019 } 1020 } 1021 buflist->bs_children[i] = bp = last_bp; 1022 if (bp->b_bio2.bio_offset == NOOFFSET) { 1023 VOP_BMAP(bp->b_vp, bp->b_loffset, &bp->b_bio2.bio_offset, 1024 NULL, NULL, BUF_CMD_WRITE); 1025 } 1026 buflist->bs_nchildren = i + 1; 1027 return (buflist); 1028 } 1029 1030 void 1031 cluster_append(struct bio *bio, struct buf *tbp) 1032 { 1033 tbp->b_cluster_next = NULL; 1034 if (bio->bio_caller_info1.cluster_head == NULL) { 1035 bio->bio_caller_info1.cluster_head = tbp; 1036 bio->bio_caller_info2.cluster_tail = tbp; 1037 } else { 1038 bio->bio_caller_info2.cluster_tail->b_cluster_next = tbp; 1039 bio->bio_caller_info2.cluster_tail = tbp; 1040 } 1041 } 1042 1043 static 1044 void 1045 cluster_setram (struct buf *bp) 1046 { 1047 bp->b_flags |= B_RAM; 1048 if (bp->b_xio.xio_npages) 1049 vm_page_flag_set(bp->b_xio.xio_pages[0], PG_RAM); 1050 } 1051