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 "Cluster write-behind setting"); 82 static int max_readahead = 2 * 1024 * 1024; 83 SYSCTL_INT(_vfs, OID_AUTO, max_readahead, CTLFLAG_RW, &max_readahead, 0, 84 "Limit in bytes for desired cluster read-ahead"); 85 86 extern vm_page_t bogus_page; 87 88 extern int cluster_pbuf_freecnt; 89 90 /* 91 * This replaces bread. 92 * 93 * filesize - read-ahead @ blksize will not cross this boundary 94 * loffset - loffset for returned *bpp 95 * blksize - blocksize for returned *bpp and read-ahead bps 96 * minreq - minimum (not a hard minimum) in bytes, typically reflects 97 * a higher level uio resid. 98 * maxreq - maximum (sequential heuristic) in bytes (highet typ ~2MB) 99 * bpp - return buffer (*bpp) for (loffset,blksize) 100 */ 101 int 102 cluster_read(struct vnode *vp, off_t filesize, off_t loffset, 103 int blksize, size_t minreq, size_t maxreq, struct buf **bpp) 104 { 105 struct buf *bp, *rbp, *reqbp; 106 off_t origoffset; 107 off_t doffset; 108 int error; 109 int i; 110 int maxra; 111 int maxrbuild; 112 113 error = 0; 114 115 /* 116 * Calculate the desired read-ahead in blksize'd blocks (maxra). 117 * To do this we calculate maxreq. 118 * 119 * maxreq typically starts out as a sequential heuristic. If the 120 * high level uio/resid is bigger (minreq), we pop maxreq up to 121 * minreq. This represents the case where random I/O is being 122 * performed by the userland is issuing big read()'s. 123 * 124 * Then we limit maxreq to max_readahead to ensure it is a reasonable 125 * value. 126 * 127 * Finally we must ensure that (loffset + maxreq) does not cross the 128 * boundary (filesize) for the current blocksize. If we allowed it 129 * to cross we could end up with buffers past the boundary with the 130 * wrong block size (HAMMER large-data areas use mixed block sizes). 131 * minreq is also absolutely limited to filesize. 132 */ 133 if (maxreq < minreq) 134 maxreq = minreq; 135 /* minreq not used beyond this point */ 136 137 if (maxreq > max_readahead) { 138 maxreq = max_readahead; 139 if (maxreq > 16 * 1024 * 1024) 140 maxreq = 16 * 1024 * 1024; 141 } 142 if (maxreq < blksize) 143 maxreq = blksize; 144 if (loffset + maxreq > filesize) { 145 if (loffset > filesize) 146 maxreq = 0; 147 else 148 maxreq = filesize - loffset; 149 } 150 151 maxra = (int)(maxreq / blksize); 152 153 /* 154 * Get the requested block. 155 */ 156 *bpp = reqbp = bp = getblk(vp, loffset, blksize, 0, 0); 157 origoffset = loffset; 158 159 /* 160 * Calculate the maximum cluster size for a single I/O, used 161 * by cluster_rbuild(). 162 */ 163 maxrbuild = vmaxiosize(vp) / blksize; 164 165 /* 166 * if it is in the cache, then check to see if the reads have been 167 * sequential. If they have, then try some read-ahead, otherwise 168 * back-off on prospective read-aheads. 169 */ 170 if (bp->b_flags & B_CACHE) { 171 /* 172 * Not sequential, do not do any read-ahead 173 */ 174 if (maxra <= 1) 175 return 0; 176 177 /* 178 * No read-ahead mark, do not do any read-ahead 179 * yet. 180 */ 181 if ((bp->b_flags & B_RAM) == 0) 182 return 0; 183 184 /* 185 * We hit a read-ahead-mark, figure out how much read-ahead 186 * to do (maxra) and where to start (loffset). 187 * 188 * Shortcut the scan. Typically the way this works is that 189 * we've built up all the blocks inbetween except for the 190 * last in previous iterations, so if the second-to-last 191 * block is present we just skip ahead to it. 192 * 193 * This algorithm has O(1) cpu in the steady state no 194 * matter how large maxra is. 195 */ 196 bp->b_flags &= ~B_RAM; 197 198 if (findblk(vp, loffset + (maxra - 2) * blksize, FINDBLK_TEST)) 199 i = maxra - 1; 200 else 201 i = 1; 202 while (i < maxra) { 203 if (findblk(vp, loffset + i * blksize, 204 FINDBLK_TEST) == NULL) { 205 break; 206 } 207 ++i; 208 } 209 210 /* 211 * We got everything or everything is in the cache, no 212 * point continuing. 213 */ 214 if (i >= maxra) 215 return 0; 216 maxra -= i; 217 loffset += i * blksize; 218 reqbp = bp = NULL; 219 } else { 220 __debugvar off_t firstread = bp->b_loffset; 221 int nblks; 222 223 /* 224 * Set-up synchronous read for bp. 225 */ 226 bp->b_cmd = BUF_CMD_READ; 227 bp->b_bio1.bio_done = biodone_sync; 228 bp->b_bio1.bio_flags |= BIO_SYNC; 229 230 KASSERT(firstread != NOOFFSET, 231 ("cluster_read: no buffer offset")); 232 233 /* 234 * nblks is our cluster_rbuild request size, limited 235 * primarily by the device. 236 */ 237 if ((nblks = maxra) > maxrbuild) 238 nblks = maxrbuild; 239 240 if (nblks > 1) { 241 int burstbytes; 242 243 error = VOP_BMAP(vp, loffset, &doffset, 244 &burstbytes, NULL, BUF_CMD_READ); 245 if (error) 246 goto single_block_read; 247 if (nblks > burstbytes / blksize) 248 nblks = burstbytes / blksize; 249 if (doffset == NOOFFSET) 250 goto single_block_read; 251 if (nblks <= 1) 252 goto single_block_read; 253 254 bp = cluster_rbuild(vp, filesize, loffset, 255 doffset, blksize, nblks, bp); 256 loffset += bp->b_bufsize; 257 maxra -= bp->b_bufsize / blksize; 258 } else { 259 single_block_read: 260 /* 261 * If it isn't in the cache, then get a chunk from 262 * disk if sequential, otherwise just get the block. 263 */ 264 cluster_setram(bp); 265 loffset += blksize; 266 --maxra; 267 } 268 } 269 270 /* 271 * If B_CACHE was not set issue bp. bp will either be an 272 * asynchronous cluster buf or a synchronous single-buf. 273 * If it is a single buf it will be the same as reqbp. 274 * 275 * NOTE: Once an async cluster buf is issued bp becomes invalid. 276 */ 277 if (bp) { 278 #if defined(CLUSTERDEBUG) 279 if (rcluster) 280 kprintf("S(%012jx,%d,%d)\n", 281 (intmax_t)bp->b_loffset, bp->b_bcount, maxra); 282 #endif 283 if ((bp->b_flags & B_CLUSTER) == 0) 284 vfs_busy_pages(vp, bp); 285 bp->b_flags &= ~(B_ERROR|B_INVAL); 286 vn_strategy(vp, &bp->b_bio1); 287 error = 0; 288 /* bp invalid now */ 289 } 290 291 /* 292 * If we have been doing sequential I/O, then do some read-ahead. 293 * The code above us should have positioned us at the next likely 294 * offset. 295 * 296 * Only mess with buffers which we can immediately lock. HAMMER 297 * will do device-readahead irrespective of what the blocks 298 * represent. 299 */ 300 while (error == 0 && maxra > 0) { 301 int burstbytes; 302 int tmp_error; 303 int nblks; 304 305 rbp = getblk(vp, loffset, blksize, 306 GETBLK_SZMATCH|GETBLK_NOWAIT, 0); 307 if (rbp == NULL) 308 goto no_read_ahead; 309 if ((rbp->b_flags & B_CACHE)) { 310 bqrelse(rbp); 311 goto no_read_ahead; 312 } 313 314 /* 315 * An error from the read-ahead bmap has nothing to do 316 * with the caller's original request. 317 */ 318 tmp_error = VOP_BMAP(vp, loffset, &doffset, 319 &burstbytes, NULL, BUF_CMD_READ); 320 if (tmp_error || doffset == NOOFFSET) { 321 rbp->b_flags |= B_INVAL; 322 brelse(rbp); 323 rbp = NULL; 324 goto no_read_ahead; 325 } 326 if ((nblks = maxra) > maxrbuild) 327 nblks = maxrbuild; 328 if (nblks > burstbytes / blksize) 329 nblks = burstbytes / blksize; 330 331 /* 332 * rbp: async read 333 */ 334 rbp->b_cmd = BUF_CMD_READ; 335 /*rbp->b_flags |= B_AGE*/; 336 cluster_setram(rbp); 337 338 if (nblks > 1) { 339 rbp = cluster_rbuild(vp, filesize, loffset, 340 doffset, blksize, 341 nblks, rbp); 342 } else { 343 rbp->b_bio2.bio_offset = doffset; 344 } 345 346 #if defined(CLUSTERDEBUG) 347 if (rcluster) { 348 if (bp) { 349 kprintf("A+(%012jx,%d,%jd) " 350 "doff=%012jx minr=%zd ra=%d\n", 351 (intmax_t)loffset, rbp->b_bcount, 352 (intmax_t)(loffset - origoffset), 353 (intmax_t)doffset, minreq, maxra); 354 } else { 355 kprintf("A-(%012jx,%d,%jd) " 356 "doff=%012jx minr=%zd ra=%d\n", 357 (intmax_t)rbp->b_loffset, rbp->b_bcount, 358 (intmax_t)(loffset - origoffset), 359 (intmax_t)doffset, minreq, maxra); 360 } 361 } 362 #endif 363 rbp->b_flags &= ~(B_ERROR|B_INVAL); 364 365 if ((rbp->b_flags & B_CLUSTER) == 0) 366 vfs_busy_pages(vp, rbp); 367 BUF_KERNPROC(rbp); 368 loffset += rbp->b_bufsize; 369 maxra -= rbp->b_bufsize / blksize; 370 vn_strategy(vp, &rbp->b_bio1); 371 /* rbp invalid now */ 372 } 373 374 /* 375 * Wait for our original buffer to complete its I/O. reqbp will 376 * be NULL if the original buffer was B_CACHE. We are returning 377 * (*bpp) which is the same as reqbp when reqbp != NULL. 378 */ 379 no_read_ahead: 380 if (reqbp) { 381 KKASSERT(reqbp->b_bio1.bio_flags & BIO_SYNC); 382 error = biowait(&reqbp->b_bio1, "clurd"); 383 } 384 return (error); 385 } 386 387 /* 388 * If blocks are contiguous on disk, use this to provide clustered 389 * read ahead. We will read as many blocks as possible sequentially 390 * and then parcel them up into logical blocks in the buffer hash table. 391 * 392 * This function either returns a cluster buf or it returns fbp. fbp is 393 * already expected to be set up as a synchronous or asynchronous request. 394 * 395 * If a cluster buf is returned it will always be async. 396 */ 397 static struct buf * 398 cluster_rbuild(struct vnode *vp, off_t filesize, off_t loffset, off_t doffset, 399 int blksize, int run, struct buf *fbp) 400 { 401 struct buf *bp, *tbp; 402 off_t boffset; 403 int i, j; 404 int maxiosize = vmaxiosize(vp); 405 406 /* 407 * avoid a division 408 */ 409 while (loffset + run * blksize > filesize) { 410 --run; 411 } 412 413 tbp = fbp; 414 tbp->b_bio2.bio_offset = doffset; 415 if((tbp->b_flags & B_MALLOC) || 416 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1)) { 417 return tbp; 418 } 419 420 bp = trypbuf_kva(&cluster_pbuf_freecnt); 421 if (bp == NULL) { 422 return tbp; 423 } 424 425 /* 426 * We are synthesizing a buffer out of vm_page_t's, but 427 * if the block size is not page aligned then the starting 428 * address may not be either. Inherit the b_data offset 429 * from the original buffer. 430 */ 431 bp->b_data = (char *)((vm_offset_t)bp->b_data | 432 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 433 bp->b_flags |= B_CLUSTER | B_VMIO; 434 bp->b_cmd = BUF_CMD_READ; 435 bp->b_bio1.bio_done = cluster_callback; /* default to async */ 436 bp->b_bio1.bio_caller_info1.cluster_head = NULL; 437 bp->b_bio1.bio_caller_info2.cluster_tail = NULL; 438 bp->b_loffset = loffset; 439 bp->b_bio2.bio_offset = doffset; 440 KASSERT(bp->b_loffset != NOOFFSET, 441 ("cluster_rbuild: no buffer offset")); 442 443 bp->b_bcount = 0; 444 bp->b_bufsize = 0; 445 bp->b_xio.xio_npages = 0; 446 447 for (boffset = doffset, i = 0; i < run; ++i, boffset += blksize) { 448 if (i) { 449 if ((bp->b_xio.xio_npages * PAGE_SIZE) + 450 round_page(blksize) > maxiosize) { 451 break; 452 } 453 454 /* 455 * Shortcut some checks and try to avoid buffers that 456 * would block in the lock. The same checks have to 457 * be made again after we officially get the buffer. 458 */ 459 tbp = getblk(vp, loffset + i * blksize, blksize, 460 GETBLK_SZMATCH|GETBLK_NOWAIT, 0); 461 if (tbp == NULL) 462 break; 463 for (j = 0; j < tbp->b_xio.xio_npages; j++) { 464 if (tbp->b_xio.xio_pages[j]->valid) 465 break; 466 } 467 if (j != tbp->b_xio.xio_npages) { 468 bqrelse(tbp); 469 break; 470 } 471 472 /* 473 * Stop scanning if the buffer is fuly valid 474 * (marked B_CACHE), or locked (may be doing a 475 * background write), or if the buffer is not 476 * VMIO backed. The clustering code can only deal 477 * with VMIO-backed buffers. 478 */ 479 if ((tbp->b_flags & (B_CACHE|B_LOCKED)) || 480 (tbp->b_flags & B_VMIO) == 0 || 481 (LIST_FIRST(&tbp->b_dep) != NULL && 482 buf_checkread(tbp)) 483 ) { 484 bqrelse(tbp); 485 break; 486 } 487 488 /* 489 * The buffer must be completely invalid in order to 490 * take part in the cluster. If it is partially valid 491 * then we stop. 492 */ 493 for (j = 0;j < tbp->b_xio.xio_npages; j++) { 494 if (tbp->b_xio.xio_pages[j]->valid) 495 break; 496 } 497 if (j != tbp->b_xio.xio_npages) { 498 bqrelse(tbp); 499 break; 500 } 501 502 /* 503 * Set a read-ahead mark as appropriate 504 */ 505 if (i == 1 || i == (run - 1)) 506 cluster_setram(tbp); 507 508 /* 509 * Depress the priority of buffers not explicitly 510 * requested. 511 */ 512 /* tbp->b_flags |= B_AGE; */ 513 514 /* 515 * Set the block number if it isn't set, otherwise 516 * if it is make sure it matches the block number we 517 * expect. 518 */ 519 if (tbp->b_bio2.bio_offset == NOOFFSET) { 520 tbp->b_bio2.bio_offset = boffset; 521 } else if (tbp->b_bio2.bio_offset != boffset) { 522 brelse(tbp); 523 break; 524 } 525 } 526 527 /* 528 * The passed-in tbp (i == 0) will already be set up for 529 * async or sync operation. All other tbp's acquire in 530 * our loop are set up for async operation. 531 */ 532 tbp->b_cmd = BUF_CMD_READ; 533 BUF_KERNPROC(tbp); 534 cluster_append(&bp->b_bio1, tbp); 535 for (j = 0; j < tbp->b_xio.xio_npages; ++j) { 536 vm_page_t m; 537 m = tbp->b_xio.xio_pages[j]; 538 vm_page_io_start(m); 539 vm_object_pip_add(m->object, 1); 540 if ((bp->b_xio.xio_npages == 0) || 541 (bp->b_xio.xio_pages[bp->b_xio.xio_npages-1] != m)) { 542 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 543 bp->b_xio.xio_npages++; 544 } 545 if ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) 546 tbp->b_xio.xio_pages[j] = bogus_page; 547 } 548 /* 549 * XXX shouldn't this be += size for both, like in 550 * cluster_wbuild()? 551 * 552 * Don't inherit tbp->b_bufsize as it may be larger due to 553 * a non-page-aligned size. Instead just aggregate using 554 * 'size'. 555 */ 556 if (tbp->b_bcount != blksize) 557 kprintf("warning: tbp->b_bcount wrong %d vs %d\n", tbp->b_bcount, blksize); 558 if (tbp->b_bufsize != blksize) 559 kprintf("warning: tbp->b_bufsize wrong %d vs %d\n", tbp->b_bufsize, blksize); 560 bp->b_bcount += blksize; 561 bp->b_bufsize += blksize; 562 } 563 564 /* 565 * Fully valid pages in the cluster are already good and do not need 566 * to be re-read from disk. Replace the page with bogus_page 567 */ 568 for (j = 0; j < bp->b_xio.xio_npages; j++) { 569 if ((bp->b_xio.xio_pages[j]->valid & VM_PAGE_BITS_ALL) == 570 VM_PAGE_BITS_ALL) { 571 bp->b_xio.xio_pages[j] = bogus_page; 572 } 573 } 574 if (bp->b_bufsize > bp->b_kvasize) { 575 panic("cluster_rbuild: b_bufsize(%d) > b_kvasize(%d)", 576 bp->b_bufsize, bp->b_kvasize); 577 } 578 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 579 (vm_page_t *)bp->b_xio.xio_pages, bp->b_xio.xio_npages); 580 BUF_KERNPROC(bp); 581 return (bp); 582 } 583 584 /* 585 * Cleanup after a clustered read or write. 586 * This is complicated by the fact that any of the buffers might have 587 * extra memory (if there were no empty buffer headers at allocbuf time) 588 * that we will need to shift around. 589 * 590 * The returned bio is &bp->b_bio1 591 */ 592 void 593 cluster_callback(struct bio *bio) 594 { 595 struct buf *bp = bio->bio_buf; 596 struct buf *tbp; 597 int error = 0; 598 599 /* 600 * Must propogate errors to all the components. A short read (EOF) 601 * is a critical error. 602 */ 603 if (bp->b_flags & B_ERROR) { 604 error = bp->b_error; 605 } else if (bp->b_bcount != bp->b_bufsize) { 606 panic("cluster_callback: unexpected EOF on cluster %p!", bio); 607 } 608 609 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_xio.xio_npages); 610 /* 611 * Move memory from the large cluster buffer into the component 612 * buffers and mark IO as done on these. Since the memory map 613 * is the same, no actual copying is required. 614 */ 615 while ((tbp = bio->bio_caller_info1.cluster_head) != NULL) { 616 bio->bio_caller_info1.cluster_head = tbp->b_cluster_next; 617 if (error) { 618 tbp->b_flags |= B_ERROR | B_IODEBUG; 619 tbp->b_error = error; 620 } else { 621 tbp->b_dirtyoff = tbp->b_dirtyend = 0; 622 tbp->b_flags &= ~(B_ERROR|B_INVAL); 623 tbp->b_flags |= B_IODEBUG; 624 /* 625 * XXX the bdwrite()/bqrelse() issued during 626 * cluster building clears B_RELBUF (see bqrelse() 627 * comment). If direct I/O was specified, we have 628 * to restore it here to allow the buffer and VM 629 * to be freed. 630 */ 631 if (tbp->b_flags & B_DIRECT) 632 tbp->b_flags |= B_RELBUF; 633 } 634 biodone(&tbp->b_bio1); 635 } 636 relpbuf(bp, &cluster_pbuf_freecnt); 637 } 638 639 /* 640 * cluster_wbuild_wb: 641 * 642 * Implement modified write build for cluster. 643 * 644 * write_behind = 0 write behind disabled 645 * write_behind = 1 write behind normal (default) 646 * write_behind = 2 write behind backed-off 647 */ 648 649 static __inline int 650 cluster_wbuild_wb(struct vnode *vp, int blksize, off_t start_loffset, int len) 651 { 652 int r = 0; 653 654 switch(write_behind) { 655 case 2: 656 if (start_loffset < len) 657 break; 658 start_loffset -= len; 659 /* fall through */ 660 case 1: 661 r = cluster_wbuild(vp, blksize, start_loffset, len); 662 /* fall through */ 663 default: 664 /* fall through */ 665 break; 666 } 667 return(r); 668 } 669 670 /* 671 * Do clustered write for FFS. 672 * 673 * Three cases: 674 * 1. Write is not sequential (write asynchronously) 675 * Write is sequential: 676 * 2. beginning of cluster - begin cluster 677 * 3. middle of a cluster - add to cluster 678 * 4. end of a cluster - asynchronously write cluster 679 */ 680 void 681 cluster_write(struct buf *bp, off_t filesize, int blksize, int seqcount) 682 { 683 struct vnode *vp; 684 off_t loffset; 685 int maxclen, cursize; 686 int async; 687 688 vp = bp->b_vp; 689 if (vp->v_type == VREG) 690 async = vp->v_mount->mnt_flag & MNT_ASYNC; 691 else 692 async = 0; 693 loffset = bp->b_loffset; 694 KASSERT(bp->b_loffset != NOOFFSET, 695 ("cluster_write: no buffer offset")); 696 697 /* Initialize vnode to beginning of file. */ 698 if (loffset == 0) 699 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0; 700 701 if (vp->v_clen == 0 || loffset != vp->v_lastw + blksize || 702 bp->b_bio2.bio_offset == NOOFFSET || 703 (bp->b_bio2.bio_offset != vp->v_lasta + blksize)) { 704 maxclen = vmaxiosize(vp); 705 if (vp->v_clen != 0) { 706 /* 707 * Next block is not sequential. 708 * 709 * If we are not writing at end of file, the process 710 * seeked to another point in the file since its last 711 * write, or we have reached our maximum cluster size, 712 * then push the previous cluster. Otherwise try 713 * reallocating to make it sequential. 714 * 715 * Change to algorithm: only push previous cluster if 716 * it was sequential from the point of view of the 717 * seqcount heuristic, otherwise leave the buffer 718 * intact so we can potentially optimize the I/O 719 * later on in the buf_daemon or update daemon 720 * flush. 721 */ 722 cursize = vp->v_lastw - vp->v_cstart + blksize; 723 if (bp->b_loffset + blksize != filesize || 724 loffset != vp->v_lastw + blksize || vp->v_clen <= cursize) { 725 if (!async && seqcount > 0) { 726 cluster_wbuild_wb(vp, blksize, 727 vp->v_cstart, cursize); 728 } 729 } else { 730 struct buf **bpp, **endbp; 731 struct cluster_save *buflist; 732 733 buflist = cluster_collectbufs(vp, bp, blksize); 734 endbp = &buflist->bs_children 735 [buflist->bs_nchildren - 1]; 736 if (VOP_REALLOCBLKS(vp, buflist)) { 737 /* 738 * Failed, push the previous cluster 739 * if *really* writing sequentially 740 * in the logical file (seqcount > 1), 741 * otherwise delay it in the hopes that 742 * the low level disk driver can 743 * optimize the write ordering. 744 */ 745 for (bpp = buflist->bs_children; 746 bpp < endbp; bpp++) 747 brelse(*bpp); 748 kfree(buflist, M_SEGMENT); 749 if (seqcount > 1) { 750 cluster_wbuild_wb(vp, 751 blksize, vp->v_cstart, 752 cursize); 753 } 754 } else { 755 /* 756 * Succeeded, keep building cluster. 757 */ 758 for (bpp = buflist->bs_children; 759 bpp <= endbp; bpp++) 760 bdwrite(*bpp); 761 kfree(buflist, M_SEGMENT); 762 vp->v_lastw = loffset; 763 vp->v_lasta = bp->b_bio2.bio_offset; 764 return; 765 } 766 } 767 } 768 /* 769 * Consider beginning a cluster. If at end of file, make 770 * cluster as large as possible, otherwise find size of 771 * existing cluster. 772 */ 773 if ((vp->v_type == VREG) && 774 bp->b_loffset + blksize != filesize && 775 (bp->b_bio2.bio_offset == NOOFFSET) && 776 (VOP_BMAP(vp, loffset, &bp->b_bio2.bio_offset, &maxclen, NULL, BUF_CMD_WRITE) || 777 bp->b_bio2.bio_offset == NOOFFSET)) { 778 bawrite(bp); 779 vp->v_clen = 0; 780 vp->v_lasta = bp->b_bio2.bio_offset; 781 vp->v_cstart = loffset + blksize; 782 vp->v_lastw = loffset; 783 return; 784 } 785 if (maxclen > blksize) 786 vp->v_clen = maxclen - blksize; 787 else 788 vp->v_clen = 0; 789 if (!async && vp->v_clen == 0) { /* I/O not contiguous */ 790 vp->v_cstart = loffset + blksize; 791 bawrite(bp); 792 } else { /* Wait for rest of cluster */ 793 vp->v_cstart = loffset; 794 bdwrite(bp); 795 } 796 } else if (loffset == vp->v_cstart + vp->v_clen) { 797 /* 798 * At end of cluster, write it out if seqcount tells us we 799 * are operating sequentially, otherwise let the buf or 800 * update daemon handle it. 801 */ 802 bdwrite(bp); 803 if (seqcount > 1) 804 cluster_wbuild_wb(vp, blksize, vp->v_cstart, 805 vp->v_clen + blksize); 806 vp->v_clen = 0; 807 vp->v_cstart = loffset + blksize; 808 } else if (vm_page_count_severe()) { 809 /* 810 * We are low on memory, get it going NOW 811 */ 812 bawrite(bp); 813 } else { 814 /* 815 * In the middle of a cluster, so just delay the I/O for now. 816 */ 817 bdwrite(bp); 818 } 819 vp->v_lastw = loffset; 820 vp->v_lasta = bp->b_bio2.bio_offset; 821 } 822 823 824 /* 825 * This is an awful lot like cluster_rbuild...wish they could be combined. 826 * The last lbn argument is the current block on which I/O is being 827 * performed. Check to see that it doesn't fall in the middle of 828 * the current block (if last_bp == NULL). 829 */ 830 int 831 cluster_wbuild(struct vnode *vp, int blksize, off_t start_loffset, int bytes) 832 { 833 struct buf *bp, *tbp; 834 int i, j; 835 int totalwritten = 0; 836 int maxiosize = vmaxiosize(vp); 837 838 while (bytes > 0) { 839 /* 840 * If the buffer is not delayed-write (i.e. dirty), or it 841 * is delayed-write but either locked or inval, it cannot 842 * partake in the clustered write. 843 */ 844 tbp = findblk(vp, start_loffset, FINDBLK_NBLOCK); 845 if (tbp == NULL || 846 (tbp->b_flags & (B_LOCKED | B_INVAL | B_DELWRI)) != B_DELWRI || 847 (LIST_FIRST(&tbp->b_dep) && buf_checkwrite(tbp))) { 848 if (tbp) 849 BUF_UNLOCK(tbp); 850 start_loffset += blksize; 851 bytes -= blksize; 852 continue; 853 } 854 bremfree(tbp); 855 KKASSERT(tbp->b_cmd == BUF_CMD_DONE); 856 857 /* 858 * Extra memory in the buffer, punt on this buffer. 859 * XXX we could handle this in most cases, but we would 860 * have to push the extra memory down to after our max 861 * possible cluster size and then potentially pull it back 862 * up if the cluster was terminated prematurely--too much 863 * hassle. 864 */ 865 if (((tbp->b_flags & (B_CLUSTEROK|B_MALLOC)) != B_CLUSTEROK) || 866 (tbp->b_bcount != tbp->b_bufsize) || 867 (tbp->b_bcount != blksize) || 868 (bytes == blksize) || 869 ((bp = getpbuf_kva(&cluster_pbuf_freecnt)) == NULL)) { 870 totalwritten += tbp->b_bufsize; 871 bawrite(tbp); 872 start_loffset += blksize; 873 bytes -= blksize; 874 continue; 875 } 876 877 /* 878 * Set up the pbuf. Track our append point with b_bcount 879 * and b_bufsize. b_bufsize is not used by the device but 880 * our caller uses it to loop clusters and we use it to 881 * detect a premature EOF on the block device. 882 */ 883 bp->b_bcount = 0; 884 bp->b_bufsize = 0; 885 bp->b_xio.xio_npages = 0; 886 bp->b_loffset = tbp->b_loffset; 887 bp->b_bio2.bio_offset = tbp->b_bio2.bio_offset; 888 889 /* 890 * We are synthesizing a buffer out of vm_page_t's, but 891 * if the block size is not page aligned then the starting 892 * address may not be either. Inherit the b_data offset 893 * from the original buffer. 894 */ 895 bp->b_data = (char *)((vm_offset_t)bp->b_data | 896 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 897 bp->b_flags &= ~B_ERROR; 898 bp->b_flags |= B_CLUSTER | B_BNOCLIP | 899 (tbp->b_flags & (B_VMIO | B_NEEDCOMMIT)); 900 bp->b_bio1.bio_caller_info1.cluster_head = NULL; 901 bp->b_bio1.bio_caller_info2.cluster_tail = NULL; 902 903 /* 904 * From this location in the file, scan forward to see 905 * if there are buffers with adjacent data that need to 906 * be written as well. 907 */ 908 for (i = 0; i < bytes; (i += blksize), (start_loffset += blksize)) { 909 if (i != 0) { /* If not the first buffer */ 910 tbp = findblk(vp, start_loffset, 911 FINDBLK_NBLOCK); 912 /* 913 * Buffer not found or could not be locked 914 * non-blocking. 915 */ 916 if (tbp == NULL) 917 break; 918 919 /* 920 * If it IS in core, but has different 921 * characteristics, then don't cluster 922 * with it. 923 */ 924 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK | 925 B_INVAL | B_DELWRI | B_NEEDCOMMIT)) 926 != (B_DELWRI | B_CLUSTEROK | 927 (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) || 928 (tbp->b_flags & B_LOCKED) || 929 (LIST_FIRST(&tbp->b_dep) && 930 buf_checkwrite(tbp)) 931 ) { 932 BUF_UNLOCK(tbp); 933 break; 934 } 935 936 /* 937 * Check that the combined cluster 938 * would make sense with regard to pages 939 * and would not be too large 940 */ 941 if ((tbp->b_bcount != blksize) || 942 ((bp->b_bio2.bio_offset + i) != 943 tbp->b_bio2.bio_offset) || 944 ((tbp->b_xio.xio_npages + bp->b_xio.xio_npages) > 945 (maxiosize / PAGE_SIZE))) { 946 BUF_UNLOCK(tbp); 947 break; 948 } 949 /* 950 * Ok, it's passed all the tests, 951 * so remove it from the free list 952 * and mark it busy. We will use it. 953 */ 954 bremfree(tbp); 955 KKASSERT(tbp->b_cmd == BUF_CMD_DONE); 956 } /* end of code for non-first buffers only */ 957 958 /* 959 * If the IO is via the VM then we do some 960 * special VM hackery (yuck). Since the buffer's 961 * block size may not be page-aligned it is possible 962 * for a page to be shared between two buffers. We 963 * have to get rid of the duplication when building 964 * the cluster. 965 */ 966 if (tbp->b_flags & B_VMIO) { 967 vm_page_t m; 968 969 if (i != 0) { /* if not first buffer */ 970 for (j = 0; j < tbp->b_xio.xio_npages; ++j) { 971 m = tbp->b_xio.xio_pages[j]; 972 if (m->flags & PG_BUSY) { 973 bqrelse(tbp); 974 goto finishcluster; 975 } 976 } 977 } 978 979 for (j = 0; j < tbp->b_xio.xio_npages; ++j) { 980 m = tbp->b_xio.xio_pages[j]; 981 vm_page_io_start(m); 982 vm_object_pip_add(m->object, 1); 983 if ((bp->b_xio.xio_npages == 0) || 984 (bp->b_xio.xio_pages[bp->b_xio.xio_npages - 1] != m)) { 985 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 986 bp->b_xio.xio_npages++; 987 } 988 } 989 } 990 bp->b_bcount += blksize; 991 bp->b_bufsize += blksize; 992 993 bundirty(tbp); 994 tbp->b_flags &= ~B_ERROR; 995 tbp->b_cmd = BUF_CMD_WRITE; 996 BUF_KERNPROC(tbp); 997 cluster_append(&bp->b_bio1, tbp); 998 999 /* 1000 * check for latent dependencies to be handled 1001 */ 1002 if (LIST_FIRST(&tbp->b_dep) != NULL) 1003 buf_start(tbp); 1004 } 1005 finishcluster: 1006 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 1007 (vm_page_t *) bp->b_xio.xio_pages, bp->b_xio.xio_npages); 1008 if (bp->b_bufsize > bp->b_kvasize) { 1009 panic( 1010 "cluster_wbuild: b_bufsize(%d) > b_kvasize(%d)\n", 1011 bp->b_bufsize, bp->b_kvasize); 1012 } 1013 totalwritten += bp->b_bufsize; 1014 bp->b_dirtyoff = 0; 1015 bp->b_dirtyend = bp->b_bufsize; 1016 bp->b_bio1.bio_done = cluster_callback; 1017 bp->b_cmd = BUF_CMD_WRITE; 1018 1019 vfs_busy_pages(vp, bp); 1020 bsetrunningbufspace(bp, bp->b_bufsize); 1021 BUF_KERNPROC(bp); 1022 vn_strategy(vp, &bp->b_bio1); 1023 1024 bytes -= i; 1025 } 1026 return totalwritten; 1027 } 1028 1029 /* 1030 * Collect together all the buffers in a cluster. 1031 * Plus add one additional buffer. 1032 */ 1033 static struct cluster_save * 1034 cluster_collectbufs(struct vnode *vp, struct buf *last_bp, int blksize) 1035 { 1036 struct cluster_save *buflist; 1037 struct buf *bp; 1038 off_t loffset; 1039 int i, len; 1040 1041 len = (int)(vp->v_lastw - vp->v_cstart + blksize) / blksize; 1042 buflist = kmalloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist), 1043 M_SEGMENT, M_WAITOK); 1044 buflist->bs_nchildren = 0; 1045 buflist->bs_children = (struct buf **) (buflist + 1); 1046 for (loffset = vp->v_cstart, i = 0; i < len; (loffset += blksize), i++) { 1047 (void) bread(vp, loffset, last_bp->b_bcount, &bp); 1048 buflist->bs_children[i] = bp; 1049 if (bp->b_bio2.bio_offset == NOOFFSET) { 1050 VOP_BMAP(bp->b_vp, bp->b_loffset, 1051 &bp->b_bio2.bio_offset, 1052 NULL, NULL, BUF_CMD_WRITE); 1053 } 1054 } 1055 buflist->bs_children[i] = bp = last_bp; 1056 if (bp->b_bio2.bio_offset == NOOFFSET) { 1057 VOP_BMAP(bp->b_vp, bp->b_loffset, &bp->b_bio2.bio_offset, 1058 NULL, NULL, BUF_CMD_WRITE); 1059 } 1060 buflist->bs_nchildren = i + 1; 1061 return (buflist); 1062 } 1063 1064 void 1065 cluster_append(struct bio *bio, struct buf *tbp) 1066 { 1067 tbp->b_cluster_next = NULL; 1068 if (bio->bio_caller_info1.cluster_head == NULL) { 1069 bio->bio_caller_info1.cluster_head = tbp; 1070 bio->bio_caller_info2.cluster_tail = tbp; 1071 } else { 1072 bio->bio_caller_info2.cluster_tail->b_cluster_next = tbp; 1073 bio->bio_caller_info2.cluster_tail = tbp; 1074 } 1075 } 1076 1077 static 1078 void 1079 cluster_setram (struct buf *bp) 1080 { 1081 bp->b_flags |= B_RAM; 1082 if (bp->b_xio.xio_npages) 1083 vm_page_flag_set(bp->b_xio.xio_pages[0], PG_RAM); 1084 } 1085