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