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 static int max_readahead = 2 * 1024 * 1024; 82 SYSCTL_INT(_vfs, OID_AUTO, max_readahead, CTLFLAG_RW, &max_readahead, 0, ""); 83 84 extern vm_page_t bogus_page; 85 86 extern int cluster_pbuf_freecnt; 87 88 /* 89 * This replaces bread. 90 * 91 * filesize - read-ahead @ blksize will not cross this boundary 92 * loffset - loffset for returned *bpp 93 * blksize - blocksize for returned *bpp and read-ahead bps 94 * minreq - minimum (not a hard minimum) in bytes, typically reflects 95 * a higher level uio resid. 96 * maxreq - maximum (sequential heuristic) in bytes (highet typ ~2MB) 97 * bpp - return buffer (*bpp) for (loffset,blksize) 98 */ 99 int 100 cluster_read(struct vnode *vp, off_t filesize, off_t loffset, 101 int blksize, size_t minreq, size_t maxreq, struct buf **bpp) 102 { 103 struct buf *bp, *rbp, *reqbp; 104 off_t origoffset; 105 off_t doffset; 106 int error; 107 int i; 108 int maxra; 109 int maxrbuild; 110 111 error = 0; 112 113 /* 114 * Calculate the desired read-ahead in blksize'd blocks (maxra). 115 * To do this we calculate maxreq. 116 * 117 * maxreq typically starts out as a sequential heuristic. If the 118 * high level uio/resid is bigger (minreq), we pop maxreq up to 119 * minreq. This represents the case where random I/O is being 120 * performed by the userland is issuing big read()'s. 121 * 122 * Then we limit maxreq to max_readahead to ensure it is a reasonable 123 * value. 124 * 125 * Finally we must ensure that loffset + maxreq does not cross the 126 * boundary (filesize) for the current blocksize. If we allowed it 127 * to cross we could end up with buffers past the boundary with the 128 * wrong block size (HAMMER large-data areas use mixed block sizes). 129 */ 130 if (maxreq < minreq) 131 maxreq = minreq; 132 if (maxreq > max_readahead) { 133 maxreq = max_readahead; 134 if (maxreq > 16 * 1024 * 1024) 135 maxreq = 16 * 1024 * 1024; 136 } 137 if (maxreq < blksize) 138 maxreq = blksize; 139 if (loffset + maxreq > filesize) { 140 if (loffset > filesize) 141 maxreq = 0; 142 else 143 maxreq = filesize - loffset; 144 } 145 146 maxra = (int)(maxreq / blksize); 147 148 /* 149 * Get the requested block. 150 */ 151 *bpp = reqbp = bp = getblk(vp, loffset, blksize, 0, 0); 152 origoffset = loffset; 153 154 /* 155 * Calculate the maximum cluster size for a single I/O, used 156 * by cluster_rbuild(). 157 */ 158 maxrbuild = vmaxiosize(vp) / blksize; 159 160 /* 161 * if it is in the cache, then check to see if the reads have been 162 * sequential. If they have, then try some read-ahead, otherwise 163 * back-off on prospective read-aheads. 164 */ 165 if (bp->b_flags & B_CACHE) { 166 /* 167 * Not sequential, do not do any read-ahead 168 */ 169 if (maxra <= 1) 170 return 0; 171 172 /* 173 * No read-ahead mark, do not do any read-ahead 174 * yet. 175 */ 176 if ((bp->b_flags & B_RAM) == 0) 177 return 0; 178 179 /* 180 * We hit a read-ahead-mark, figure out how much read-ahead 181 * to do (maxra) and where to start (loffset). 182 * 183 * Shortcut the scan. Typically the way this works is that 184 * we've built up all the blocks inbetween except for the 185 * last in previous iterations, so if the second-to-last 186 * block is present we just skip ahead to it. 187 * 188 * This algorithm has O(1) cpu in the steady state no 189 * matter how large maxra is. 190 */ 191 bp->b_flags &= ~B_RAM; 192 193 if (findblk(vp, loffset + (maxra - 2) * blksize, FINDBLK_TEST)) 194 i = maxra - 1; 195 else 196 i = 1; 197 while (i < maxra) { 198 if (findblk(vp, loffset + i * blksize, 199 FINDBLK_TEST) == NULL) { 200 break; 201 } 202 ++i; 203 } 204 205 /* 206 * We got everything or everything is in the cache, no 207 * point continuing. 208 */ 209 if (i >= maxra) 210 return 0; 211 maxra -= i; 212 loffset += i * blksize; 213 reqbp = bp = NULL; 214 } else { 215 __debugvar off_t firstread = bp->b_loffset; 216 int nblks; 217 218 /* 219 * Set-up synchronous read for bp. 220 */ 221 bp->b_cmd = BUF_CMD_READ; 222 bp->b_bio1.bio_done = biodone_sync; 223 bp->b_bio1.bio_flags |= BIO_SYNC; 224 225 KASSERT(firstread != NOOFFSET, 226 ("cluster_read: no buffer offset")); 227 228 /* 229 * nblks is our cluster_rbuild request size, limited 230 * primarily by the device. 231 */ 232 if ((nblks = maxra) > maxrbuild) 233 nblks = maxrbuild; 234 235 if (nblks > 1) { 236 int burstbytes; 237 238 error = VOP_BMAP(vp, loffset, &doffset, 239 &burstbytes, NULL, BUF_CMD_READ); 240 if (error) 241 goto single_block_read; 242 if (nblks > burstbytes / blksize) 243 nblks = burstbytes / blksize; 244 if (doffset == NOOFFSET) 245 goto single_block_read; 246 if (nblks <= 1) 247 goto single_block_read; 248 249 bp = cluster_rbuild(vp, filesize, loffset, 250 doffset, blksize, nblks, bp); 251 loffset += bp->b_bufsize; 252 maxra -= bp->b_bufsize / blksize; 253 } else { 254 single_block_read: 255 /* 256 * If it isn't in the cache, then get a chunk from 257 * disk if sequential, otherwise just get the block. 258 */ 259 cluster_setram(bp); 260 loffset += blksize; 261 --maxra; 262 } 263 } 264 265 /* 266 * If B_CACHE was not set issue bp. bp will either be an 267 * asynchronous cluster buf or a synchronous single-buf. 268 * If it is a single buf it will be the same as reqbp. 269 * 270 * NOTE: Once an async cluster buf is issued bp becomes invalid. 271 */ 272 if (bp) { 273 #if defined(CLUSTERDEBUG) 274 if (rcluster) 275 kprintf("S(%012jx,%d,%d)\n", 276 (intmax_t)bp->b_loffset, bp->b_bcount, maxra); 277 #endif 278 if ((bp->b_flags & B_CLUSTER) == 0) 279 vfs_busy_pages(vp, bp); 280 bp->b_flags &= ~(B_ERROR|B_INVAL); 281 vn_strategy(vp, &bp->b_bio1); 282 error = 0; 283 /* bp invalid now */ 284 } 285 286 /* 287 * If we have been doing sequential I/O, then do some read-ahead. 288 * The code above us should have positioned us at the next likely 289 * offset. 290 * 291 * Only mess with buffers which we can immediately lock. HAMMER 292 * will do device-readahead irrespective of what the blocks 293 * represent. 294 */ 295 while (error == 0 && maxra > 0) { 296 int burstbytes; 297 int tmp_error; 298 int nblks; 299 300 rbp = getblk(vp, loffset, blksize, 301 GETBLK_SZMATCH|GETBLK_NOWAIT, 0); 302 if (rbp == NULL) 303 goto no_read_ahead; 304 if ((rbp->b_flags & B_CACHE)) { 305 bqrelse(rbp); 306 goto no_read_ahead; 307 } 308 309 /* 310 * An error from the read-ahead bmap has nothing to do 311 * with the caller's original request. 312 */ 313 tmp_error = VOP_BMAP(vp, loffset, &doffset, 314 &burstbytes, NULL, BUF_CMD_READ); 315 if (tmp_error || doffset == NOOFFSET) { 316 rbp->b_flags |= B_INVAL; 317 brelse(rbp); 318 rbp = NULL; 319 goto no_read_ahead; 320 } 321 if ((nblks = maxra) > maxrbuild) 322 nblks = maxrbuild; 323 if (nblks > burstbytes / blksize) 324 nblks = burstbytes / blksize; 325 326 /* 327 * rbp: async read 328 */ 329 rbp->b_cmd = BUF_CMD_READ; 330 /*rbp->b_flags |= B_AGE*/; 331 cluster_setram(rbp); 332 333 if (nblks > 1) { 334 rbp = cluster_rbuild(vp, filesize, loffset, 335 doffset, blksize, 336 nblks, rbp); 337 } else { 338 rbp->b_bio2.bio_offset = doffset; 339 } 340 341 #if defined(CLUSTERDEBUG) 342 if (rcluster) { 343 if (bp) { 344 kprintf("A+(%012jx,%d,%jd) " 345 "doff=%012jx minr=%zd ra=%d\n", 346 (intmax_t)loffset, rbp->b_bcount, 347 (intmax_t)(loffset - origoffset), 348 (intmax_t)doffset, minreq, maxra); 349 } else { 350 kprintf("A-(%012jx,%d,%jd) " 351 "doff=%012jx minr=%zd ra=%d\n", 352 (intmax_t)rbp->b_loffset, rbp->b_bcount, 353 (intmax_t)(loffset - origoffset), 354 (intmax_t)doffset, minreq, maxra); 355 } 356 } 357 #endif 358 rbp->b_flags &= ~(B_ERROR|B_INVAL); 359 360 if ((rbp->b_flags & B_CLUSTER) == 0) 361 vfs_busy_pages(vp, rbp); 362 BUF_KERNPROC(rbp); 363 loffset += rbp->b_bufsize; 364 maxra -= rbp->b_bufsize / blksize; 365 vn_strategy(vp, &rbp->b_bio1); 366 /* rbp invalid now */ 367 } 368 369 /* 370 * Wait for our original buffer to complete its I/O. reqbp will 371 * be NULL if the original buffer was B_CACHE. We are returning 372 * (*bpp) which is the same as reqbp when reqbp != NULL. 373 */ 374 no_read_ahead: 375 if (reqbp) { 376 KKASSERT(reqbp->b_bio1.bio_flags & BIO_SYNC); 377 error = biowait(&reqbp->b_bio1, "clurd"); 378 } 379 return (error); 380 } 381 382 /* 383 * If blocks are contiguous on disk, use this to provide clustered 384 * read ahead. We will read as many blocks as possible sequentially 385 * and then parcel them up into logical blocks in the buffer hash table. 386 * 387 * This function either returns a cluster buf or it returns fbp. fbp is 388 * already expected to be set up as a synchronous or asynchronous request. 389 * 390 * If a cluster buf is returned it will always be async. 391 */ 392 static struct buf * 393 cluster_rbuild(struct vnode *vp, off_t filesize, off_t loffset, off_t doffset, 394 int blksize, int run, struct buf *fbp) 395 { 396 struct buf *bp, *tbp; 397 off_t boffset; 398 int i, j; 399 int maxiosize = vmaxiosize(vp); 400 401 /* 402 * avoid a division 403 */ 404 while (loffset + run * blksize > filesize) { 405 --run; 406 } 407 408 tbp = fbp; 409 tbp->b_bio2.bio_offset = doffset; 410 if((tbp->b_flags & B_MALLOC) || 411 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1)) { 412 return tbp; 413 } 414 415 bp = trypbuf_kva(&cluster_pbuf_freecnt); 416 if (bp == NULL) { 417 return tbp; 418 } 419 420 /* 421 * We are synthesizing a buffer out of vm_page_t's, but 422 * if the block size is not page aligned then the starting 423 * address may not be either. Inherit the b_data offset 424 * from the original buffer. 425 */ 426 bp->b_data = (char *)((vm_offset_t)bp->b_data | 427 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 428 bp->b_flags |= B_CLUSTER | B_VMIO; 429 bp->b_cmd = BUF_CMD_READ; 430 bp->b_bio1.bio_done = cluster_callback; /* default to async */ 431 bp->b_bio1.bio_caller_info1.cluster_head = NULL; 432 bp->b_bio1.bio_caller_info2.cluster_tail = NULL; 433 bp->b_loffset = loffset; 434 bp->b_bio2.bio_offset = doffset; 435 KASSERT(bp->b_loffset != NOOFFSET, 436 ("cluster_rbuild: no buffer offset")); 437 438 bp->b_bcount = 0; 439 bp->b_bufsize = 0; 440 bp->b_xio.xio_npages = 0; 441 442 for (boffset = doffset, i = 0; i < run; ++i, boffset += blksize) { 443 if (i) { 444 if ((bp->b_xio.xio_npages * PAGE_SIZE) + 445 round_page(blksize) > maxiosize) { 446 break; 447 } 448 449 /* 450 * Shortcut some checks and try to avoid buffers that 451 * would block in the lock. The same checks have to 452 * be made again after we officially get the buffer. 453 */ 454 tbp = getblk(vp, loffset + i * blksize, blksize, 455 GETBLK_SZMATCH|GETBLK_NOWAIT, 0); 456 if (tbp == NULL) 457 break; 458 for (j = 0; j < tbp->b_xio.xio_npages; j++) { 459 if (tbp->b_xio.xio_pages[j]->valid) 460 break; 461 } 462 if (j != tbp->b_xio.xio_npages) { 463 bqrelse(tbp); 464 break; 465 } 466 467 /* 468 * Stop scanning if the buffer is fuly valid 469 * (marked B_CACHE), or locked (may be doing a 470 * background write), or if the buffer is not 471 * VMIO backed. The clustering code can only deal 472 * with VMIO-backed buffers. 473 */ 474 if ((tbp->b_flags & (B_CACHE|B_LOCKED)) || 475 (tbp->b_flags & B_VMIO) == 0 || 476 (LIST_FIRST(&tbp->b_dep) != NULL && 477 buf_checkread(tbp)) 478 ) { 479 bqrelse(tbp); 480 break; 481 } 482 483 /* 484 * The buffer must be completely invalid in order to 485 * take part in the cluster. If it is partially valid 486 * then we stop. 487 */ 488 for (j = 0;j < tbp->b_xio.xio_npages; j++) { 489 if (tbp->b_xio.xio_pages[j]->valid) 490 break; 491 } 492 if (j != tbp->b_xio.xio_npages) { 493 bqrelse(tbp); 494 break; 495 } 496 497 /* 498 * Set a read-ahead mark as appropriate 499 */ 500 if (i == 1 || i == (run - 1)) 501 cluster_setram(tbp); 502 503 /* 504 * Depress the priority of buffers not explicitly 505 * requested. 506 */ 507 /* tbp->b_flags |= B_AGE; */ 508 509 /* 510 * Set the block number if it isn't set, otherwise 511 * if it is make sure it matches the block number we 512 * expect. 513 */ 514 if (tbp->b_bio2.bio_offset == NOOFFSET) { 515 tbp->b_bio2.bio_offset = boffset; 516 } else if (tbp->b_bio2.bio_offset != boffset) { 517 brelse(tbp); 518 break; 519 } 520 } 521 522 /* 523 * The passed-in tbp (i == 0) will already be set up for 524 * async or sync operation. All other tbp's acquire in 525 * our loop are set up for async operation. 526 */ 527 tbp->b_cmd = BUF_CMD_READ; 528 BUF_KERNPROC(tbp); 529 cluster_append(&bp->b_bio1, tbp); 530 for (j = 0; j < tbp->b_xio.xio_npages; ++j) { 531 vm_page_t m; 532 m = tbp->b_xio.xio_pages[j]; 533 vm_page_io_start(m); 534 vm_object_pip_add(m->object, 1); 535 if ((bp->b_xio.xio_npages == 0) || 536 (bp->b_xio.xio_pages[bp->b_xio.xio_npages-1] != m)) { 537 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 538 bp->b_xio.xio_npages++; 539 } 540 if ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) 541 tbp->b_xio.xio_pages[j] = bogus_page; 542 } 543 /* 544 * XXX shouldn't this be += size for both, like in 545 * cluster_wbuild()? 546 * 547 * Don't inherit tbp->b_bufsize as it may be larger due to 548 * a non-page-aligned size. Instead just aggregate using 549 * 'size'. 550 */ 551 if (tbp->b_bcount != blksize) 552 kprintf("warning: tbp->b_bcount wrong %d vs %d\n", tbp->b_bcount, blksize); 553 if (tbp->b_bufsize != blksize) 554 kprintf("warning: tbp->b_bufsize wrong %d vs %d\n", tbp->b_bufsize, blksize); 555 bp->b_bcount += blksize; 556 bp->b_bufsize += blksize; 557 } 558 559 /* 560 * Fully valid pages in the cluster are already good and do not need 561 * to be re-read from disk. Replace the page with bogus_page 562 */ 563 for (j = 0; j < bp->b_xio.xio_npages; j++) { 564 if ((bp->b_xio.xio_pages[j]->valid & VM_PAGE_BITS_ALL) == 565 VM_PAGE_BITS_ALL) { 566 bp->b_xio.xio_pages[j] = bogus_page; 567 } 568 } 569 if (bp->b_bufsize > bp->b_kvasize) { 570 panic("cluster_rbuild: b_bufsize(%d) > b_kvasize(%d)", 571 bp->b_bufsize, bp->b_kvasize); 572 } 573 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 574 (vm_page_t *)bp->b_xio.xio_pages, bp->b_xio.xio_npages); 575 BUF_KERNPROC(bp); 576 return (bp); 577 } 578 579 /* 580 * Cleanup after a clustered read or write. 581 * This is complicated by the fact that any of the buffers might have 582 * extra memory (if there were no empty buffer headers at allocbuf time) 583 * that we will need to shift around. 584 * 585 * The returned bio is &bp->b_bio1 586 */ 587 void 588 cluster_callback(struct bio *bio) 589 { 590 struct buf *bp = bio->bio_buf; 591 struct buf *tbp; 592 int error = 0; 593 594 /* 595 * Must propogate errors to all the components. A short read (EOF) 596 * is a critical error. 597 */ 598 if (bp->b_flags & B_ERROR) { 599 error = bp->b_error; 600 } else if (bp->b_bcount != bp->b_bufsize) { 601 panic("cluster_callback: unexpected EOF on cluster %p!", bio); 602 } 603 604 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_xio.xio_npages); 605 /* 606 * Move memory from the large cluster buffer into the component 607 * buffers and mark IO as done on these. Since the memory map 608 * is the same, no actual copying is required. 609 */ 610 while ((tbp = bio->bio_caller_info1.cluster_head) != NULL) { 611 bio->bio_caller_info1.cluster_head = tbp->b_cluster_next; 612 if (error) { 613 tbp->b_flags |= B_ERROR | B_IODEBUG; 614 tbp->b_error = error; 615 } else { 616 tbp->b_dirtyoff = tbp->b_dirtyend = 0; 617 tbp->b_flags &= ~(B_ERROR|B_INVAL); 618 tbp->b_flags |= B_IODEBUG; 619 /* 620 * XXX the bdwrite()/bqrelse() issued during 621 * cluster building clears B_RELBUF (see bqrelse() 622 * comment). If direct I/O was specified, we have 623 * to restore it here to allow the buffer and VM 624 * to be freed. 625 */ 626 if (tbp->b_flags & B_DIRECT) 627 tbp->b_flags |= B_RELBUF; 628 } 629 biodone(&tbp->b_bio1); 630 } 631 relpbuf(bp, &cluster_pbuf_freecnt); 632 } 633 634 /* 635 * cluster_wbuild_wb: 636 * 637 * Implement modified write build for cluster. 638 * 639 * write_behind = 0 write behind disabled 640 * write_behind = 1 write behind normal (default) 641 * write_behind = 2 write behind backed-off 642 */ 643 644 static __inline int 645 cluster_wbuild_wb(struct vnode *vp, int blksize, off_t start_loffset, int len) 646 { 647 int r = 0; 648 649 switch(write_behind) { 650 case 2: 651 if (start_loffset < len) 652 break; 653 start_loffset -= len; 654 /* fall through */ 655 case 1: 656 r = cluster_wbuild(vp, blksize, start_loffset, len); 657 /* fall through */ 658 default: 659 /* fall through */ 660 break; 661 } 662 return(r); 663 } 664 665 /* 666 * Do clustered write for FFS. 667 * 668 * Three cases: 669 * 1. Write is not sequential (write asynchronously) 670 * Write is sequential: 671 * 2. beginning of cluster - begin cluster 672 * 3. middle of a cluster - add to cluster 673 * 4. end of a cluster - asynchronously write cluster 674 */ 675 void 676 cluster_write(struct buf *bp, off_t filesize, int blksize, int seqcount) 677 { 678 struct vnode *vp; 679 off_t loffset; 680 int maxclen, cursize; 681 int async; 682 683 vp = bp->b_vp; 684 if (vp->v_type == VREG) 685 async = vp->v_mount->mnt_flag & MNT_ASYNC; 686 else 687 async = 0; 688 loffset = bp->b_loffset; 689 KASSERT(bp->b_loffset != NOOFFSET, 690 ("cluster_write: no buffer offset")); 691 692 /* Initialize vnode to beginning of file. */ 693 if (loffset == 0) 694 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0; 695 696 if (vp->v_clen == 0 || loffset != vp->v_lastw + blksize || 697 bp->b_bio2.bio_offset == NOOFFSET || 698 (bp->b_bio2.bio_offset != vp->v_lasta + blksize)) { 699 maxclen = vmaxiosize(vp); 700 if (vp->v_clen != 0) { 701 /* 702 * Next block is not sequential. 703 * 704 * If we are not writing at end of file, the process 705 * seeked to another point in the file since its last 706 * write, or we have reached our maximum cluster size, 707 * then push the previous cluster. Otherwise try 708 * reallocating to make it sequential. 709 * 710 * Change to algorithm: only push previous cluster if 711 * it was sequential from the point of view of the 712 * seqcount heuristic, otherwise leave the buffer 713 * intact so we can potentially optimize the I/O 714 * later on in the buf_daemon or update daemon 715 * flush. 716 */ 717 cursize = vp->v_lastw - vp->v_cstart + blksize; 718 if (bp->b_loffset + blksize != filesize || 719 loffset != vp->v_lastw + blksize || vp->v_clen <= cursize) { 720 if (!async && seqcount > 0) { 721 cluster_wbuild_wb(vp, blksize, 722 vp->v_cstart, cursize); 723 } 724 } else { 725 struct buf **bpp, **endbp; 726 struct cluster_save *buflist; 727 728 buflist = cluster_collectbufs(vp, bp, blksize); 729 endbp = &buflist->bs_children 730 [buflist->bs_nchildren - 1]; 731 if (VOP_REALLOCBLKS(vp, buflist)) { 732 /* 733 * Failed, push the previous cluster 734 * if *really* writing sequentially 735 * in the logical file (seqcount > 1), 736 * otherwise delay it in the hopes that 737 * the low level disk driver can 738 * optimize the write ordering. 739 */ 740 for (bpp = buflist->bs_children; 741 bpp < endbp; bpp++) 742 brelse(*bpp); 743 kfree(buflist, M_SEGMENT); 744 if (seqcount > 1) { 745 cluster_wbuild_wb(vp, 746 blksize, vp->v_cstart, 747 cursize); 748 } 749 } else { 750 /* 751 * Succeeded, keep building cluster. 752 */ 753 for (bpp = buflist->bs_children; 754 bpp <= endbp; bpp++) 755 bdwrite(*bpp); 756 kfree(buflist, M_SEGMENT); 757 vp->v_lastw = loffset; 758 vp->v_lasta = bp->b_bio2.bio_offset; 759 return; 760 } 761 } 762 } 763 /* 764 * Consider beginning a cluster. If at end of file, make 765 * cluster as large as possible, otherwise find size of 766 * existing cluster. 767 */ 768 if ((vp->v_type == VREG) && 769 bp->b_loffset + blksize != filesize && 770 (bp->b_bio2.bio_offset == NOOFFSET) && 771 (VOP_BMAP(vp, loffset, &bp->b_bio2.bio_offset, &maxclen, NULL, BUF_CMD_WRITE) || 772 bp->b_bio2.bio_offset == NOOFFSET)) { 773 bawrite(bp); 774 vp->v_clen = 0; 775 vp->v_lasta = bp->b_bio2.bio_offset; 776 vp->v_cstart = loffset + blksize; 777 vp->v_lastw = loffset; 778 return; 779 } 780 if (maxclen > blksize) 781 vp->v_clen = maxclen - blksize; 782 else 783 vp->v_clen = 0; 784 if (!async && vp->v_clen == 0) { /* I/O not contiguous */ 785 vp->v_cstart = loffset + blksize; 786 bawrite(bp); 787 } else { /* Wait for rest of cluster */ 788 vp->v_cstart = loffset; 789 bdwrite(bp); 790 } 791 } else if (loffset == vp->v_cstart + vp->v_clen) { 792 /* 793 * At end of cluster, write it out if seqcount tells us we 794 * are operating sequentially, otherwise let the buf or 795 * update daemon handle it. 796 */ 797 bdwrite(bp); 798 if (seqcount > 1) 799 cluster_wbuild_wb(vp, blksize, vp->v_cstart, 800 vp->v_clen + blksize); 801 vp->v_clen = 0; 802 vp->v_cstart = loffset + blksize; 803 } else if (vm_page_count_severe()) { 804 /* 805 * We are low on memory, get it going NOW 806 */ 807 bawrite(bp); 808 } else { 809 /* 810 * In the middle of a cluster, so just delay the I/O for now. 811 */ 812 bdwrite(bp); 813 } 814 vp->v_lastw = loffset; 815 vp->v_lasta = bp->b_bio2.bio_offset; 816 } 817 818 819 /* 820 * This is an awful lot like cluster_rbuild...wish they could be combined. 821 * The last lbn argument is the current block on which I/O is being 822 * performed. Check to see that it doesn't fall in the middle of 823 * the current block (if last_bp == NULL). 824 */ 825 int 826 cluster_wbuild(struct vnode *vp, int blksize, off_t start_loffset, int bytes) 827 { 828 struct buf *bp, *tbp; 829 int i, j; 830 int totalwritten = 0; 831 int maxiosize = vmaxiosize(vp); 832 833 while (bytes > 0) { 834 /* 835 * If the buffer is not delayed-write (i.e. dirty), or it 836 * is delayed-write but either locked or inval, it cannot 837 * partake in the clustered write. 838 */ 839 tbp = findblk(vp, start_loffset, FINDBLK_NBLOCK); 840 if (tbp == NULL || 841 (tbp->b_flags & (B_LOCKED | B_INVAL | B_DELWRI)) != B_DELWRI || 842 (LIST_FIRST(&tbp->b_dep) && buf_checkwrite(tbp))) { 843 if (tbp) 844 BUF_UNLOCK(tbp); 845 start_loffset += blksize; 846 bytes -= blksize; 847 continue; 848 } 849 bremfree(tbp); 850 KKASSERT(tbp->b_cmd == BUF_CMD_DONE); 851 852 /* 853 * Extra memory in the buffer, punt on this buffer. 854 * XXX we could handle this in most cases, but we would 855 * have to push the extra memory down to after our max 856 * possible cluster size and then potentially pull it back 857 * up if the cluster was terminated prematurely--too much 858 * hassle. 859 */ 860 if (((tbp->b_flags & (B_CLUSTEROK|B_MALLOC)) != B_CLUSTEROK) || 861 (tbp->b_bcount != tbp->b_bufsize) || 862 (tbp->b_bcount != blksize) || 863 (bytes == blksize) || 864 ((bp = getpbuf_kva(&cluster_pbuf_freecnt)) == NULL)) { 865 totalwritten += tbp->b_bufsize; 866 bawrite(tbp); 867 start_loffset += blksize; 868 bytes -= blksize; 869 continue; 870 } 871 872 /* 873 * Set up the pbuf. Track our append point with b_bcount 874 * and b_bufsize. b_bufsize is not used by the device but 875 * our caller uses it to loop clusters and we use it to 876 * detect a premature EOF on the block device. 877 */ 878 bp->b_bcount = 0; 879 bp->b_bufsize = 0; 880 bp->b_xio.xio_npages = 0; 881 bp->b_loffset = tbp->b_loffset; 882 bp->b_bio2.bio_offset = tbp->b_bio2.bio_offset; 883 884 /* 885 * We are synthesizing a buffer out of vm_page_t's, but 886 * if the block size is not page aligned then the starting 887 * address may not be either. Inherit the b_data offset 888 * from the original buffer. 889 */ 890 bp->b_data = (char *)((vm_offset_t)bp->b_data | 891 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 892 bp->b_flags &= ~B_ERROR; 893 bp->b_flags |= B_CLUSTER | B_BNOCLIP | 894 (tbp->b_flags & (B_VMIO | B_NEEDCOMMIT)); 895 bp->b_bio1.bio_caller_info1.cluster_head = NULL; 896 bp->b_bio1.bio_caller_info2.cluster_tail = NULL; 897 898 /* 899 * From this location in the file, scan forward to see 900 * if there are buffers with adjacent data that need to 901 * be written as well. 902 */ 903 for (i = 0; i < bytes; (i += blksize), (start_loffset += blksize)) { 904 if (i != 0) { /* If not the first buffer */ 905 tbp = findblk(vp, start_loffset, 906 FINDBLK_NBLOCK); 907 /* 908 * Buffer not found or could not be locked 909 * non-blocking. 910 */ 911 if (tbp == NULL) 912 break; 913 914 /* 915 * If it IS in core, but has different 916 * characteristics, then don't cluster 917 * with it. 918 */ 919 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK | 920 B_INVAL | B_DELWRI | B_NEEDCOMMIT)) 921 != (B_DELWRI | B_CLUSTEROK | 922 (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) || 923 (tbp->b_flags & B_LOCKED) || 924 (LIST_FIRST(&tbp->b_dep) && 925 buf_checkwrite(tbp)) 926 ) { 927 BUF_UNLOCK(tbp); 928 break; 929 } 930 931 /* 932 * Check that the combined cluster 933 * would make sense with regard to pages 934 * and would not be too large 935 */ 936 if ((tbp->b_bcount != blksize) || 937 ((bp->b_bio2.bio_offset + i) != 938 tbp->b_bio2.bio_offset) || 939 ((tbp->b_xio.xio_npages + bp->b_xio.xio_npages) > 940 (maxiosize / PAGE_SIZE))) { 941 BUF_UNLOCK(tbp); 942 break; 943 } 944 /* 945 * Ok, it's passed all the tests, 946 * so remove it from the free list 947 * and mark it busy. We will use it. 948 */ 949 bremfree(tbp); 950 KKASSERT(tbp->b_cmd == BUF_CMD_DONE); 951 } /* end of code for non-first buffers only */ 952 953 /* 954 * If the IO is via the VM then we do some 955 * special VM hackery (yuck). Since the buffer's 956 * block size may not be page-aligned it is possible 957 * for a page to be shared between two buffers. We 958 * have to get rid of the duplication when building 959 * the cluster. 960 */ 961 if (tbp->b_flags & B_VMIO) { 962 vm_page_t m; 963 964 if (i != 0) { /* if not first buffer */ 965 for (j = 0; j < tbp->b_xio.xio_npages; ++j) { 966 m = tbp->b_xio.xio_pages[j]; 967 if (m->flags & PG_BUSY) { 968 bqrelse(tbp); 969 goto finishcluster; 970 } 971 } 972 } 973 974 for (j = 0; j < tbp->b_xio.xio_npages; ++j) { 975 m = tbp->b_xio.xio_pages[j]; 976 vm_page_io_start(m); 977 vm_object_pip_add(m->object, 1); 978 if ((bp->b_xio.xio_npages == 0) || 979 (bp->b_xio.xio_pages[bp->b_xio.xio_npages - 1] != m)) { 980 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 981 bp->b_xio.xio_npages++; 982 } 983 } 984 } 985 bp->b_bcount += blksize; 986 bp->b_bufsize += blksize; 987 988 bundirty(tbp); 989 tbp->b_flags &= ~B_ERROR; 990 tbp->b_cmd = BUF_CMD_WRITE; 991 BUF_KERNPROC(tbp); 992 cluster_append(&bp->b_bio1, tbp); 993 994 /* 995 * check for latent dependencies to be handled 996 */ 997 if (LIST_FIRST(&tbp->b_dep) != NULL) 998 buf_start(tbp); 999 } 1000 finishcluster: 1001 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 1002 (vm_page_t *) bp->b_xio.xio_pages, bp->b_xio.xio_npages); 1003 if (bp->b_bufsize > bp->b_kvasize) { 1004 panic( 1005 "cluster_wbuild: b_bufsize(%d) > b_kvasize(%d)\n", 1006 bp->b_bufsize, bp->b_kvasize); 1007 } 1008 totalwritten += bp->b_bufsize; 1009 bp->b_dirtyoff = 0; 1010 bp->b_dirtyend = bp->b_bufsize; 1011 bp->b_bio1.bio_done = cluster_callback; 1012 bp->b_cmd = BUF_CMD_WRITE; 1013 1014 vfs_busy_pages(vp, bp); 1015 bp->b_runningbufspace = bp->b_bufsize; 1016 if (bp->b_runningbufspace) { 1017 runningbufspace += bp->b_runningbufspace; 1018 ++runningbufcount; 1019 } 1020 BUF_KERNPROC(bp); 1021 vn_strategy(vp, &bp->b_bio1); 1022 1023 bytes -= i; 1024 } 1025 return totalwritten; 1026 } 1027 1028 /* 1029 * Collect together all the buffers in a cluster. 1030 * Plus add one additional buffer. 1031 */ 1032 static struct cluster_save * 1033 cluster_collectbufs(struct vnode *vp, struct buf *last_bp, int blksize) 1034 { 1035 struct cluster_save *buflist; 1036 struct buf *bp; 1037 off_t loffset; 1038 int i, len; 1039 1040 len = (int)(vp->v_lastw - vp->v_cstart + blksize) / blksize; 1041 buflist = kmalloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist), 1042 M_SEGMENT, M_WAITOK); 1043 buflist->bs_nchildren = 0; 1044 buflist->bs_children = (struct buf **) (buflist + 1); 1045 for (loffset = vp->v_cstart, i = 0; i < len; (loffset += blksize), i++) { 1046 (void) bread(vp, loffset, last_bp->b_bcount, &bp); 1047 buflist->bs_children[i] = bp; 1048 if (bp->b_bio2.bio_offset == NOOFFSET) { 1049 VOP_BMAP(bp->b_vp, bp->b_loffset, 1050 &bp->b_bio2.bio_offset, 1051 NULL, NULL, BUF_CMD_WRITE); 1052 } 1053 } 1054 buflist->bs_children[i] = bp = last_bp; 1055 if (bp->b_bio2.bio_offset == NOOFFSET) { 1056 VOP_BMAP(bp->b_vp, bp->b_loffset, &bp->b_bio2.bio_offset, 1057 NULL, NULL, BUF_CMD_WRITE); 1058 } 1059 buflist->bs_nchildren = i + 1; 1060 return (buflist); 1061 } 1062 1063 void 1064 cluster_append(struct bio *bio, struct buf *tbp) 1065 { 1066 tbp->b_cluster_next = NULL; 1067 if (bio->bio_caller_info1.cluster_head == NULL) { 1068 bio->bio_caller_info1.cluster_head = tbp; 1069 bio->bio_caller_info2.cluster_tail = tbp; 1070 } else { 1071 bio->bio_caller_info2.cluster_tail->b_cluster_next = tbp; 1072 bio->bio_caller_info2.cluster_tail = tbp; 1073 } 1074 } 1075 1076 static 1077 void 1078 cluster_setram (struct buf *bp) 1079 { 1080 bp->b_flags |= B_RAM; 1081 if (bp->b_xio.xio_npages) 1082 vm_page_flag_set(bp->b_xio.xio_pages[0], PG_RAM); 1083 } 1084