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