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 57 #include <sys/buf2.h> 58 #include <vm/vm_page2.h> 59 60 #include <machine/limits.h> 61 62 #if defined(CLUSTERDEBUG) 63 #include <sys/sysctl.h> 64 static int rcluster= 0; 65 SYSCTL_INT(_debug, OID_AUTO, rcluster, CTLFLAG_RW, &rcluster, 0, ""); 66 #endif 67 68 static MALLOC_DEFINE(M_SEGMENT, "cluster_save", "cluster_save buffer"); 69 70 static struct cluster_save * 71 cluster_collectbufs (struct vnode *vp, struct buf *last_bp, 72 int blksize); 73 static struct buf * 74 cluster_rbuild (struct vnode *vp, off_t filesize, off_t loffset, 75 off_t doffset, int blksize, int run, 76 struct buf *fbp); 77 static void cluster_callback (struct bio *); 78 static void cluster_setram (struct buf *); 79 static int cluster_wbuild(struct vnode *vp, struct buf **bpp, int blksize, 80 off_t start_loffset, int bytes); 81 82 static int write_behind = 1; 83 SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0, 84 "Cluster write-behind setting"); 85 static int max_readahead = 2 * 1024 * 1024; 86 SYSCTL_INT(_vfs, OID_AUTO, max_readahead, CTLFLAG_RW, &max_readahead, 0, 87 "Limit in bytes for desired cluster read-ahead"); 88 89 extern vm_page_t bogus_page; 90 91 extern int cluster_pbuf_freecnt; 92 93 /* 94 * This replaces bread. 95 * 96 * filesize - read-ahead @ blksize will not cross this boundary 97 * loffset - loffset for returned *bpp 98 * blksize - blocksize for returned *bpp and read-ahead bps 99 * minreq - minimum (not a hard minimum) in bytes, typically reflects 100 * a higher level uio resid. 101 * maxreq - maximum (sequential heuristic) in bytes (highet typ ~2MB) 102 * bpp - return buffer (*bpp) for (loffset,blksize) 103 */ 104 int 105 cluster_readx(struct vnode *vp, off_t filesize, off_t loffset, 106 int blksize, size_t minreq, size_t maxreq, struct buf **bpp) 107 { 108 struct buf *bp, *rbp, *reqbp; 109 off_t origoffset; 110 off_t doffset; 111 int error; 112 int i; 113 int maxra; 114 int maxrbuild; 115 116 error = 0; 117 118 /* 119 * Calculate the desired read-ahead in blksize'd blocks (maxra). 120 * To do this we calculate maxreq. 121 * 122 * maxreq typically starts out as a sequential heuristic. If the 123 * high level uio/resid is bigger (minreq), we pop maxreq up to 124 * minreq. This represents the case where random I/O is being 125 * performed by the userland is issuing big read()'s. 126 * 127 * Then we limit maxreq to max_readahead to ensure it is a reasonable 128 * value. 129 * 130 * Finally we must ensure that (loffset + maxreq) does not cross the 131 * boundary (filesize) for the current blocksize. If we allowed it 132 * to cross we could end up with buffers past the boundary with the 133 * wrong block size (HAMMER large-data areas use mixed block sizes). 134 * minreq is also absolutely limited to filesize. 135 */ 136 if (maxreq < minreq) 137 maxreq = minreq; 138 /* minreq not used beyond this point */ 139 140 if (maxreq > max_readahead) { 141 maxreq = max_readahead; 142 if (maxreq > 16 * 1024 * 1024) 143 maxreq = 16 * 1024 * 1024; 144 } 145 if (maxreq < blksize) 146 maxreq = blksize; 147 if (loffset + maxreq > filesize) { 148 if (loffset > filesize) 149 maxreq = 0; 150 else 151 maxreq = filesize - loffset; 152 } 153 154 maxra = (int)(maxreq / blksize); 155 156 /* 157 * Get the requested block. 158 */ 159 if (*bpp) 160 reqbp = bp = *bpp; 161 else 162 *bpp = reqbp = bp = getblk(vp, loffset, blksize, 0, 0); 163 origoffset = loffset; 164 165 /* 166 * Calculate the maximum cluster size for a single I/O, used 167 * by cluster_rbuild(). 168 */ 169 maxrbuild = vmaxiosize(vp) / blksize; 170 171 /* 172 * if it is in the cache, then check to see if the reads have been 173 * sequential. If they have, then try some read-ahead, otherwise 174 * back-off on prospective read-aheads. 175 */ 176 if (bp->b_flags & B_CACHE) { 177 /* 178 * Not sequential, do not do any read-ahead 179 */ 180 if (maxra <= 1) 181 return 0; 182 183 /* 184 * No read-ahead mark, do not do any read-ahead 185 * yet. 186 */ 187 if ((bp->b_flags & B_RAM) == 0) 188 return 0; 189 190 /* 191 * We hit a read-ahead-mark, figure out how much read-ahead 192 * to do (maxra) and where to start (loffset). 193 * 194 * Shortcut the scan. Typically the way this works is that 195 * we've built up all the blocks inbetween except for the 196 * last in previous iterations, so if the second-to-last 197 * block is present we just skip ahead to it. 198 * 199 * This algorithm has O(1) cpu in the steady state no 200 * matter how large maxra is. 201 */ 202 bp->b_flags &= ~B_RAM; 203 204 if (findblk(vp, loffset + (maxra - 2) * blksize, FINDBLK_TEST)) 205 i = maxra - 1; 206 else 207 i = 1; 208 while (i < maxra) { 209 if (findblk(vp, loffset + i * blksize, 210 FINDBLK_TEST) == NULL) { 211 break; 212 } 213 ++i; 214 } 215 216 /* 217 * We got everything or everything is in the cache, no 218 * point continuing. 219 */ 220 if (i >= maxra) 221 return 0; 222 223 /* 224 * Calculate where to start the read-ahead and how much 225 * to do. Generally speaking we want to read-ahead by 226 * (maxra) when we've found a read-ahead mark. We do 227 * not want to reduce maxra here as it will cause 228 * successive read-ahead I/O's to be smaller and smaller. 229 * 230 * However, we have to make sure we don't break the 231 * filesize limitation for the clustered operation. 232 */ 233 loffset += i * blksize; 234 reqbp = bp = NULL; 235 236 if (loffset >= filesize) 237 return 0; 238 if (loffset + maxra * blksize > filesize) { 239 maxreq = filesize - loffset; 240 maxra = (int)(maxreq / blksize); 241 } 242 } else { 243 __debugvar off_t firstread = bp->b_loffset; 244 int nblks; 245 246 /* 247 * Set-up synchronous read for bp. 248 */ 249 bp->b_cmd = BUF_CMD_READ; 250 bp->b_bio1.bio_done = biodone_sync; 251 bp->b_bio1.bio_flags |= BIO_SYNC; 252 253 KASSERT(firstread != NOOFFSET, 254 ("cluster_read: no buffer offset")); 255 256 /* 257 * nblks is our cluster_rbuild request size, limited 258 * primarily by the device. 259 */ 260 if ((nblks = maxra) > maxrbuild) 261 nblks = maxrbuild; 262 263 if (nblks > 1) { 264 int burstbytes; 265 266 error = VOP_BMAP(vp, loffset, &doffset, 267 &burstbytes, NULL, BUF_CMD_READ); 268 if (error) 269 goto single_block_read; 270 if (nblks > burstbytes / blksize) 271 nblks = burstbytes / blksize; 272 if (doffset == NOOFFSET) 273 goto single_block_read; 274 if (nblks <= 1) 275 goto single_block_read; 276 277 bp = cluster_rbuild(vp, filesize, loffset, 278 doffset, blksize, nblks, bp); 279 loffset += bp->b_bufsize; 280 maxra -= bp->b_bufsize / blksize; 281 } else { 282 single_block_read: 283 /* 284 * If it isn't in the cache, then get a chunk from 285 * disk if sequential, otherwise just get the block. 286 */ 287 cluster_setram(bp); 288 loffset += blksize; 289 --maxra; 290 } 291 } 292 293 /* 294 * If B_CACHE was not set issue bp. bp will either be an 295 * asynchronous cluster buf or a synchronous single-buf. 296 * If it is a single buf it will be the same as reqbp. 297 * 298 * NOTE: Once an async cluster buf is issued bp becomes invalid. 299 */ 300 if (bp) { 301 #if defined(CLUSTERDEBUG) 302 if (rcluster) 303 kprintf("S(%012jx,%d,%d)\n", 304 (intmax_t)bp->b_loffset, bp->b_bcount, maxra); 305 #endif 306 if ((bp->b_flags & B_CLUSTER) == 0) 307 vfs_busy_pages(vp, bp); 308 bp->b_flags &= ~(B_ERROR|B_INVAL); 309 vn_strategy(vp, &bp->b_bio1); 310 error = 0; 311 /* bp invalid now */ 312 } 313 314 /* 315 * If we have been doing sequential I/O, then do some read-ahead. 316 * The code above us should have positioned us at the next likely 317 * offset. 318 * 319 * Only mess with buffers which we can immediately lock. HAMMER 320 * will do device-readahead irrespective of what the blocks 321 * represent. 322 */ 323 while (error == 0 && maxra > 0) { 324 int burstbytes; 325 int tmp_error; 326 int nblks; 327 328 rbp = getblk(vp, loffset, blksize, 329 GETBLK_SZMATCH|GETBLK_NOWAIT, 0); 330 if (rbp == NULL) 331 goto no_read_ahead; 332 if ((rbp->b_flags & B_CACHE)) { 333 bqrelse(rbp); 334 goto no_read_ahead; 335 } 336 337 /* 338 * An error from the read-ahead bmap has nothing to do 339 * with the caller's original request. 340 */ 341 tmp_error = VOP_BMAP(vp, loffset, &doffset, 342 &burstbytes, NULL, BUF_CMD_READ); 343 if (tmp_error || doffset == NOOFFSET) { 344 rbp->b_flags |= B_INVAL; 345 brelse(rbp); 346 rbp = NULL; 347 goto no_read_ahead; 348 } 349 if ((nblks = maxra) > maxrbuild) 350 nblks = maxrbuild; 351 if (nblks > burstbytes / blksize) 352 nblks = burstbytes / blksize; 353 354 /* 355 * rbp: async read 356 */ 357 rbp->b_cmd = BUF_CMD_READ; 358 /*rbp->b_flags |= B_AGE*/; 359 cluster_setram(rbp); 360 361 if (nblks > 1) { 362 rbp = cluster_rbuild(vp, filesize, loffset, 363 doffset, blksize, 364 nblks, rbp); 365 } else { 366 rbp->b_bio2.bio_offset = doffset; 367 } 368 369 #if defined(CLUSTERDEBUG) 370 if (rcluster) { 371 if (bp) { 372 kprintf("A+(%012jx,%d,%jd) " 373 "doff=%012jx minr=%zd ra=%d\n", 374 (intmax_t)loffset, rbp->b_bcount, 375 (intmax_t)(loffset - origoffset), 376 (intmax_t)doffset, minreq, maxra); 377 } else { 378 kprintf("A-(%012jx,%d,%jd) " 379 "doff=%012jx minr=%zd ra=%d\n", 380 (intmax_t)rbp->b_loffset, rbp->b_bcount, 381 (intmax_t)(loffset - origoffset), 382 (intmax_t)doffset, minreq, maxra); 383 } 384 } 385 #endif 386 rbp->b_flags &= ~(B_ERROR|B_INVAL); 387 388 if ((rbp->b_flags & B_CLUSTER) == 0) 389 vfs_busy_pages(vp, rbp); 390 BUF_KERNPROC(rbp); 391 loffset += rbp->b_bufsize; 392 maxra -= rbp->b_bufsize / blksize; 393 vn_strategy(vp, &rbp->b_bio1); 394 /* rbp invalid now */ 395 } 396 397 /* 398 * Wait for our original buffer to complete its I/O. reqbp will 399 * be NULL if the original buffer was B_CACHE. We are returning 400 * (*bpp) which is the same as reqbp when reqbp != NULL. 401 */ 402 no_read_ahead: 403 if (reqbp) { 404 KKASSERT(reqbp->b_bio1.bio_flags & BIO_SYNC); 405 error = biowait(&reqbp->b_bio1, "clurd"); 406 } 407 return (error); 408 } 409 410 /* 411 * If blocks are contiguous on disk, use this to provide clustered 412 * read ahead. We will read as many blocks as possible sequentially 413 * and then parcel them up into logical blocks in the buffer hash table. 414 * 415 * This function either returns a cluster buf or it returns fbp. fbp is 416 * already expected to be set up as a synchronous or asynchronous request. 417 * 418 * If a cluster buf is returned it will always be async. 419 */ 420 static struct buf * 421 cluster_rbuild(struct vnode *vp, off_t filesize, off_t loffset, off_t doffset, 422 int blksize, int run, struct buf *fbp) 423 { 424 struct buf *bp, *tbp; 425 off_t boffset; 426 int i, j; 427 int maxiosize = vmaxiosize(vp); 428 429 /* 430 * avoid a division 431 */ 432 while (loffset + run * blksize > filesize) { 433 --run; 434 } 435 436 tbp = fbp; 437 tbp->b_bio2.bio_offset = doffset; 438 if((tbp->b_flags & B_MALLOC) || 439 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1)) { 440 return tbp; 441 } 442 443 bp = trypbuf_kva(&cluster_pbuf_freecnt); 444 if (bp == NULL) { 445 return tbp; 446 } 447 448 /* 449 * We are synthesizing a buffer out of vm_page_t's, but 450 * if the block size is not page aligned then the starting 451 * address may not be either. Inherit the b_data offset 452 * from the original buffer. 453 */ 454 bp->b_data = (char *)((vm_offset_t)bp->b_data | 455 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 456 bp->b_flags |= B_CLUSTER | B_VMIO; 457 bp->b_cmd = BUF_CMD_READ; 458 bp->b_bio1.bio_done = cluster_callback; /* default to async */ 459 bp->b_bio1.bio_caller_info1.cluster_head = NULL; 460 bp->b_bio1.bio_caller_info2.cluster_tail = NULL; 461 bp->b_loffset = loffset; 462 bp->b_bio2.bio_offset = doffset; 463 KASSERT(bp->b_loffset != NOOFFSET, 464 ("cluster_rbuild: no buffer offset")); 465 466 bp->b_bcount = 0; 467 bp->b_bufsize = 0; 468 bp->b_xio.xio_npages = 0; 469 470 for (boffset = doffset, i = 0; i < run; ++i, boffset += blksize) { 471 if (i) { 472 if ((bp->b_xio.xio_npages * PAGE_SIZE) + 473 round_page(blksize) > maxiosize) { 474 break; 475 } 476 477 /* 478 * Shortcut some checks and try to avoid buffers that 479 * would block in the lock. The same checks have to 480 * be made again after we officially get the buffer. 481 */ 482 tbp = getblk(vp, loffset + i * blksize, blksize, 483 GETBLK_SZMATCH|GETBLK_NOWAIT, 0); 484 if (tbp == NULL) 485 break; 486 for (j = 0; j < tbp->b_xio.xio_npages; j++) { 487 if (tbp->b_xio.xio_pages[j]->valid) 488 break; 489 } 490 if (j != tbp->b_xio.xio_npages) { 491 bqrelse(tbp); 492 break; 493 } 494 495 /* 496 * Stop scanning if the buffer is fuly valid 497 * (marked B_CACHE), or locked (may be doing a 498 * background write), or if the buffer is not 499 * VMIO backed. The clustering code can only deal 500 * with VMIO-backed buffers. 501 */ 502 if ((tbp->b_flags & (B_CACHE|B_LOCKED)) || 503 (tbp->b_flags & B_VMIO) == 0 || 504 (LIST_FIRST(&tbp->b_dep) != NULL && 505 buf_checkread(tbp)) 506 ) { 507 bqrelse(tbp); 508 break; 509 } 510 511 /* 512 * The buffer must be completely invalid in order to 513 * take part in the cluster. If it is partially valid 514 * then we stop. 515 */ 516 for (j = 0;j < tbp->b_xio.xio_npages; j++) { 517 if (tbp->b_xio.xio_pages[j]->valid) 518 break; 519 } 520 if (j != tbp->b_xio.xio_npages) { 521 bqrelse(tbp); 522 break; 523 } 524 525 /* 526 * Set a read-ahead mark as appropriate. Always 527 * set the read-ahead mark at (run - 1). It is 528 * unclear why we were also setting it at i == 1. 529 */ 530 if (/*i == 1 ||*/ i == (run - 1)) 531 cluster_setram(tbp); 532 533 /* 534 * Depress the priority of buffers not explicitly 535 * requested. 536 */ 537 /* tbp->b_flags |= B_AGE; */ 538 539 /* 540 * Set the block number if it isn't set, otherwise 541 * if it is make sure it matches the block number we 542 * expect. 543 */ 544 if (tbp->b_bio2.bio_offset == NOOFFSET) { 545 tbp->b_bio2.bio_offset = boffset; 546 } else if (tbp->b_bio2.bio_offset != boffset) { 547 brelse(tbp); 548 break; 549 } 550 } 551 552 /* 553 * The passed-in tbp (i == 0) will already be set up for 554 * async or sync operation. All other tbp's acquire in 555 * our loop are set up for async operation. 556 */ 557 tbp->b_cmd = BUF_CMD_READ; 558 BUF_KERNPROC(tbp); 559 cluster_append(&bp->b_bio1, tbp); 560 for (j = 0; j < tbp->b_xio.xio_npages; ++j) { 561 vm_page_t m; 562 563 m = tbp->b_xio.xio_pages[j]; 564 vm_page_busy_wait(m, FALSE, "clurpg"); 565 vm_page_io_start(m); 566 vm_page_wakeup(m); 567 vm_object_pip_add(m->object, 1); 568 if ((bp->b_xio.xio_npages == 0) || 569 (bp->b_xio.xio_pages[bp->b_xio.xio_npages-1] != m)) { 570 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 571 bp->b_xio.xio_npages++; 572 } 573 if ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) 574 tbp->b_xio.xio_pages[j] = bogus_page; 575 } 576 /* 577 * XXX shouldn't this be += size for both, like in 578 * cluster_wbuild()? 579 * 580 * Don't inherit tbp->b_bufsize as it may be larger due to 581 * a non-page-aligned size. Instead just aggregate using 582 * 'size'. 583 */ 584 if (tbp->b_bcount != blksize) 585 kprintf("warning: tbp->b_bcount wrong %d vs %d\n", tbp->b_bcount, blksize); 586 if (tbp->b_bufsize != blksize) 587 kprintf("warning: tbp->b_bufsize wrong %d vs %d\n", tbp->b_bufsize, blksize); 588 bp->b_bcount += blksize; 589 bp->b_bufsize += blksize; 590 } 591 592 /* 593 * Fully valid pages in the cluster are already good and do not need 594 * to be re-read from disk. Replace the page with bogus_page 595 */ 596 for (j = 0; j < bp->b_xio.xio_npages; j++) { 597 if ((bp->b_xio.xio_pages[j]->valid & VM_PAGE_BITS_ALL) == 598 VM_PAGE_BITS_ALL) { 599 bp->b_xio.xio_pages[j] = bogus_page; 600 } 601 } 602 if (bp->b_bufsize > bp->b_kvasize) { 603 panic("cluster_rbuild: b_bufsize(%d) > b_kvasize(%d)", 604 bp->b_bufsize, bp->b_kvasize); 605 } 606 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 607 (vm_page_t *)bp->b_xio.xio_pages, bp->b_xio.xio_npages); 608 BUF_KERNPROC(bp); 609 return (bp); 610 } 611 612 /* 613 * Cleanup after a clustered read or write. 614 * This is complicated by the fact that any of the buffers might have 615 * extra memory (if there were no empty buffer headers at allocbuf time) 616 * that we will need to shift around. 617 * 618 * The returned bio is &bp->b_bio1 619 */ 620 void 621 cluster_callback(struct bio *bio) 622 { 623 struct buf *bp = bio->bio_buf; 624 struct buf *tbp; 625 int error = 0; 626 627 /* 628 * Must propogate errors to all the components. A short read (EOF) 629 * is a critical error. 630 */ 631 if (bp->b_flags & B_ERROR) { 632 error = bp->b_error; 633 } else if (bp->b_bcount != bp->b_bufsize) { 634 panic("cluster_callback: unexpected EOF on cluster %p!", bio); 635 } 636 637 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_xio.xio_npages); 638 /* 639 * Move memory from the large cluster buffer into the component 640 * buffers and mark IO as done on these. Since the memory map 641 * is the same, no actual copying is required. 642 */ 643 while ((tbp = bio->bio_caller_info1.cluster_head) != NULL) { 644 bio->bio_caller_info1.cluster_head = tbp->b_cluster_next; 645 if (error) { 646 tbp->b_flags |= B_ERROR | B_IODEBUG; 647 tbp->b_error = error; 648 } else { 649 tbp->b_dirtyoff = tbp->b_dirtyend = 0; 650 tbp->b_flags &= ~(B_ERROR|B_INVAL); 651 tbp->b_flags |= B_IODEBUG; 652 /* 653 * XXX the bdwrite()/bqrelse() issued during 654 * cluster building clears B_RELBUF (see bqrelse() 655 * comment). If direct I/O was specified, we have 656 * to restore it here to allow the buffer and VM 657 * to be freed. 658 */ 659 if (tbp->b_flags & B_DIRECT) 660 tbp->b_flags |= B_RELBUF; 661 } 662 biodone(&tbp->b_bio1); 663 } 664 relpbuf(bp, &cluster_pbuf_freecnt); 665 } 666 667 /* 668 * cluster_wbuild_wb: 669 * 670 * Implement modified write build for cluster. 671 * 672 * write_behind = 0 write behind disabled 673 * write_behind = 1 write behind normal (default) 674 * write_behind = 2 write behind backed-off 675 */ 676 677 static __inline int 678 cluster_wbuild_wb(struct vnode *vp, int blksize, off_t start_loffset, int len) 679 { 680 int r = 0; 681 682 switch(write_behind) { 683 case 2: 684 if (start_loffset < len) 685 break; 686 start_loffset -= len; 687 /* fall through */ 688 case 1: 689 r = cluster_wbuild(vp, NULL, blksize, start_loffset, len); 690 /* fall through */ 691 default: 692 /* fall through */ 693 break; 694 } 695 return(r); 696 } 697 698 /* 699 * Do clustered write for FFS. 700 * 701 * Three cases: 702 * 1. Write is not sequential (write asynchronously) 703 * Write is sequential: 704 * 2. beginning of cluster - begin cluster 705 * 3. middle of a cluster - add to cluster 706 * 4. end of a cluster - asynchronously write cluster 707 */ 708 void 709 cluster_write(struct buf *bp, off_t filesize, int blksize, int seqcount) 710 { 711 struct vnode *vp; 712 off_t loffset; 713 int maxclen, cursize; 714 int async; 715 716 vp = bp->b_vp; 717 if (vp->v_type == VREG) 718 async = vp->v_mount->mnt_flag & MNT_ASYNC; 719 else 720 async = 0; 721 loffset = bp->b_loffset; 722 KASSERT(bp->b_loffset != NOOFFSET, 723 ("cluster_write: no buffer offset")); 724 725 /* Initialize vnode to beginning of file. */ 726 if (loffset == 0) 727 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0; 728 729 if (vp->v_clen == 0 || loffset != vp->v_lastw + blksize || 730 bp->b_bio2.bio_offset == NOOFFSET || 731 (bp->b_bio2.bio_offset != vp->v_lasta + blksize)) { 732 maxclen = vmaxiosize(vp); 733 if (vp->v_clen != 0) { 734 /* 735 * Next block is not sequential. 736 * 737 * If we are not writing at end of file, the process 738 * seeked to another point in the file since its last 739 * write, or we have reached our maximum cluster size, 740 * then push the previous cluster. Otherwise try 741 * reallocating to make it sequential. 742 * 743 * Change to algorithm: only push previous cluster if 744 * it was sequential from the point of view of the 745 * seqcount heuristic, otherwise leave the buffer 746 * intact so we can potentially optimize the I/O 747 * later on in the buf_daemon or update daemon 748 * flush. 749 */ 750 cursize = vp->v_lastw - vp->v_cstart + blksize; 751 if (bp->b_loffset + blksize < filesize || 752 loffset != vp->v_lastw + blksize || vp->v_clen <= cursize) { 753 if (!async && seqcount > 0) { 754 cluster_wbuild_wb(vp, blksize, 755 vp->v_cstart, cursize); 756 } 757 } else { 758 struct buf **bpp, **endbp; 759 struct cluster_save *buflist; 760 761 buflist = cluster_collectbufs(vp, bp, blksize); 762 endbp = &buflist->bs_children 763 [buflist->bs_nchildren - 1]; 764 if (VOP_REALLOCBLKS(vp, buflist)) { 765 /* 766 * Failed, push the previous cluster 767 * if *really* writing sequentially 768 * in the logical file (seqcount > 1), 769 * otherwise delay it in the hopes that 770 * the low level disk driver can 771 * optimize the write ordering. 772 */ 773 for (bpp = buflist->bs_children; 774 bpp < endbp; bpp++) 775 brelse(*bpp); 776 kfree(buflist, M_SEGMENT); 777 if (seqcount > 1) { 778 cluster_wbuild_wb(vp, 779 blksize, vp->v_cstart, 780 cursize); 781 } 782 } else { 783 /* 784 * Succeeded, keep building cluster. 785 */ 786 for (bpp = buflist->bs_children; 787 bpp <= endbp; bpp++) 788 bdwrite(*bpp); 789 kfree(buflist, M_SEGMENT); 790 vp->v_lastw = loffset; 791 vp->v_lasta = bp->b_bio2.bio_offset; 792 return; 793 } 794 } 795 } 796 /* 797 * Consider beginning a cluster. If at end of file, make 798 * cluster as large as possible, otherwise find size of 799 * existing cluster. 800 */ 801 if ((vp->v_type == VREG) && 802 bp->b_loffset + blksize < filesize && 803 (bp->b_bio2.bio_offset == NOOFFSET) && 804 (VOP_BMAP(vp, loffset, &bp->b_bio2.bio_offset, &maxclen, NULL, BUF_CMD_WRITE) || 805 bp->b_bio2.bio_offset == NOOFFSET)) { 806 bawrite(bp); 807 vp->v_clen = 0; 808 vp->v_lasta = bp->b_bio2.bio_offset; 809 vp->v_cstart = loffset + blksize; 810 vp->v_lastw = loffset; 811 return; 812 } 813 if (maxclen > blksize) 814 vp->v_clen = maxclen - blksize; 815 else 816 vp->v_clen = 0; 817 if (!async && vp->v_clen == 0) { /* I/O not contiguous */ 818 vp->v_cstart = loffset + blksize; 819 bawrite(bp); 820 } else { /* Wait for rest of cluster */ 821 vp->v_cstart = loffset; 822 bdwrite(bp); 823 } 824 } else if (loffset == vp->v_cstart + vp->v_clen) { 825 /* 826 * At end of cluster, write it out if seqcount tells us we 827 * are operating sequentially, otherwise let the buf or 828 * update daemon handle it. 829 */ 830 bdwrite(bp); 831 if (seqcount > 1) 832 cluster_wbuild_wb(vp, blksize, vp->v_cstart, 833 vp->v_clen + blksize); 834 vp->v_clen = 0; 835 vp->v_cstart = loffset + blksize; 836 } else if (vm_page_count_severe()) { 837 /* 838 * We are low on memory, get it going NOW 839 */ 840 bawrite(bp); 841 } else { 842 /* 843 * In the middle of a cluster, so just delay the I/O for now. 844 */ 845 bdwrite(bp); 846 } 847 vp->v_lastw = loffset; 848 vp->v_lasta = bp->b_bio2.bio_offset; 849 } 850 851 /* 852 * This is the clustered version of bawrite(). It works similarly to 853 * cluster_write() except I/O on the buffer is guaranteed to occur. 854 */ 855 int 856 cluster_awrite(struct buf *bp) 857 { 858 int total; 859 860 /* 861 * Don't bother if it isn't clusterable. 862 */ 863 if ((bp->b_flags & B_CLUSTEROK) == 0 || 864 bp->b_vp == NULL || 865 (bp->b_vp->v_flag & VOBJBUF) == 0) { 866 total = bp->b_bufsize; 867 bawrite(bp); 868 return (total); 869 } 870 871 total = cluster_wbuild(bp->b_vp, &bp, bp->b_bufsize, 872 bp->b_loffset, vmaxiosize(bp->b_vp)); 873 if (bp) 874 bawrite(bp); 875 876 return total; 877 } 878 879 /* 880 * This is an awful lot like cluster_rbuild...wish they could be combined. 881 * The last lbn argument is the current block on which I/O is being 882 * performed. Check to see that it doesn't fall in the middle of 883 * the current block (if last_bp == NULL). 884 * 885 * cluster_wbuild() normally does not guarantee anything. If bpp is 886 * non-NULL and cluster_wbuild() is able to incorporate it into the 887 * I/O it will set *bpp to NULL, otherwise it will leave it alone and 888 * the caller must dispose of *bpp. 889 */ 890 static int 891 cluster_wbuild(struct vnode *vp, struct buf **bpp, 892 int blksize, off_t start_loffset, int bytes) 893 { 894 struct buf *bp, *tbp; 895 int i, j; 896 int totalwritten = 0; 897 int must_initiate; 898 int maxiosize = vmaxiosize(vp); 899 900 while (bytes > 0) { 901 /* 902 * If the buffer matches the passed locked & removed buffer 903 * we used the passed buffer (which might not be B_DELWRI). 904 * 905 * Otherwise locate the buffer and determine if it is 906 * compatible. 907 */ 908 if (bpp && (*bpp)->b_loffset == start_loffset) { 909 tbp = *bpp; 910 *bpp = NULL; 911 bpp = NULL; 912 } else { 913 tbp = findblk(vp, start_loffset, FINDBLK_NBLOCK); 914 if (tbp == NULL || 915 (tbp->b_flags & (B_LOCKED | B_INVAL | B_DELWRI)) != 916 B_DELWRI || 917 (LIST_FIRST(&tbp->b_dep) && buf_checkwrite(tbp))) { 918 if (tbp) 919 BUF_UNLOCK(tbp); 920 start_loffset += blksize; 921 bytes -= blksize; 922 continue; 923 } 924 bremfree(tbp); 925 } 926 KKASSERT(tbp->b_cmd == BUF_CMD_DONE); 927 928 /* 929 * Extra memory in the buffer, punt on this buffer. 930 * XXX we could handle this in most cases, but we would 931 * have to push the extra memory down to after our max 932 * possible cluster size and then potentially pull it back 933 * up if the cluster was terminated prematurely--too much 934 * hassle. 935 */ 936 if (((tbp->b_flags & (B_CLUSTEROK|B_MALLOC)) != B_CLUSTEROK) || 937 (tbp->b_bcount != tbp->b_bufsize) || 938 (tbp->b_bcount != blksize) || 939 (bytes == blksize) || 940 ((bp = getpbuf_kva(&cluster_pbuf_freecnt)) == NULL)) { 941 totalwritten += tbp->b_bufsize; 942 bawrite(tbp); 943 start_loffset += blksize; 944 bytes -= blksize; 945 continue; 946 } 947 948 /* 949 * Set up the pbuf. Track our append point with b_bcount 950 * and b_bufsize. b_bufsize is not used by the device but 951 * our caller uses it to loop clusters and we use it to 952 * detect a premature EOF on the block device. 953 */ 954 bp->b_bcount = 0; 955 bp->b_bufsize = 0; 956 bp->b_xio.xio_npages = 0; 957 bp->b_loffset = tbp->b_loffset; 958 bp->b_bio2.bio_offset = tbp->b_bio2.bio_offset; 959 960 /* 961 * We are synthesizing a buffer out of vm_page_t's, but 962 * if the block size is not page aligned then the starting 963 * address may not be either. Inherit the b_data offset 964 * from the original buffer. 965 */ 966 bp->b_data = (char *)((vm_offset_t)bp->b_data | 967 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 968 bp->b_flags &= ~B_ERROR; 969 bp->b_flags |= B_CLUSTER | B_BNOCLIP | 970 (tbp->b_flags & (B_VMIO | B_NEEDCOMMIT)); 971 bp->b_bio1.bio_caller_info1.cluster_head = NULL; 972 bp->b_bio1.bio_caller_info2.cluster_tail = NULL; 973 974 /* 975 * From this location in the file, scan forward to see 976 * if there are buffers with adjacent data that need to 977 * be written as well. 978 * 979 * IO *must* be initiated on index 0 at this point 980 * (particularly when called from cluster_awrite()). 981 */ 982 for (i = 0; i < bytes; (i += blksize), (start_loffset += blksize)) { 983 if (i == 0) { 984 must_initiate = 1; 985 } else { 986 /* 987 * Not first buffer. 988 */ 989 must_initiate = 0; 990 tbp = findblk(vp, start_loffset, 991 FINDBLK_NBLOCK); 992 /* 993 * Buffer not found or could not be locked 994 * non-blocking. 995 */ 996 if (tbp == NULL) 997 break; 998 999 /* 1000 * If it IS in core, but has different 1001 * characteristics, then don't cluster 1002 * with it. 1003 */ 1004 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK | 1005 B_INVAL | B_DELWRI | B_NEEDCOMMIT)) 1006 != (B_DELWRI | B_CLUSTEROK | 1007 (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) || 1008 (tbp->b_flags & B_LOCKED) 1009 ) { 1010 BUF_UNLOCK(tbp); 1011 break; 1012 } 1013 1014 /* 1015 * Check that the combined cluster 1016 * would make sense with regard to pages 1017 * and would not be too large 1018 * 1019 * WARNING! buf_checkwrite() must be the last 1020 * check made. If it returns 0 then 1021 * we must initiate the I/O. 1022 */ 1023 if ((tbp->b_bcount != blksize) || 1024 ((bp->b_bio2.bio_offset + i) != 1025 tbp->b_bio2.bio_offset) || 1026 ((tbp->b_xio.xio_npages + bp->b_xio.xio_npages) > 1027 (maxiosize / PAGE_SIZE)) || 1028 (LIST_FIRST(&tbp->b_dep) && 1029 buf_checkwrite(tbp)) 1030 ) { 1031 BUF_UNLOCK(tbp); 1032 break; 1033 } 1034 if (LIST_FIRST(&tbp->b_dep)) 1035 must_initiate = 1; 1036 /* 1037 * Ok, it's passed all the tests, 1038 * so remove it from the free list 1039 * and mark it busy. We will use it. 1040 */ 1041 bremfree(tbp); 1042 KKASSERT(tbp->b_cmd == BUF_CMD_DONE); 1043 } 1044 1045 /* 1046 * If the IO is via the VM then we do some 1047 * special VM hackery (yuck). Since the buffer's 1048 * block size may not be page-aligned it is possible 1049 * for a page to be shared between two buffers. We 1050 * have to get rid of the duplication when building 1051 * the cluster. 1052 */ 1053 if (tbp->b_flags & B_VMIO) { 1054 vm_page_t m; 1055 1056 /* 1057 * Try to avoid deadlocks with the VM system. 1058 * However, we cannot abort the I/O if 1059 * must_initiate is non-zero. 1060 */ 1061 if (must_initiate == 0) { 1062 for (j = 0; 1063 j < tbp->b_xio.xio_npages; 1064 ++j) { 1065 m = tbp->b_xio.xio_pages[j]; 1066 if (m->flags & PG_BUSY) { 1067 bqrelse(tbp); 1068 goto finishcluster; 1069 } 1070 } 1071 } 1072 1073 for (j = 0; j < tbp->b_xio.xio_npages; ++j) { 1074 m = tbp->b_xio.xio_pages[j]; 1075 vm_page_busy_wait(m, FALSE, "clurpg"); 1076 vm_page_io_start(m); 1077 vm_page_wakeup(m); 1078 vm_object_pip_add(m->object, 1); 1079 if ((bp->b_xio.xio_npages == 0) || 1080 (bp->b_xio.xio_pages[bp->b_xio.xio_npages - 1] != m)) { 1081 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 1082 bp->b_xio.xio_npages++; 1083 } 1084 } 1085 } 1086 bp->b_bcount += blksize; 1087 bp->b_bufsize += blksize; 1088 1089 bundirty(tbp); 1090 tbp->b_flags &= ~B_ERROR; 1091 tbp->b_cmd = BUF_CMD_WRITE; 1092 BUF_KERNPROC(tbp); 1093 cluster_append(&bp->b_bio1, tbp); 1094 1095 /* 1096 * check for latent dependencies to be handled 1097 */ 1098 if (LIST_FIRST(&tbp->b_dep) != NULL) 1099 buf_start(tbp); 1100 } 1101 finishcluster: 1102 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 1103 (vm_page_t *)bp->b_xio.xio_pages, 1104 bp->b_xio.xio_npages); 1105 if (bp->b_bufsize > bp->b_kvasize) { 1106 panic("cluster_wbuild: b_bufsize(%d) " 1107 "> b_kvasize(%d)\n", 1108 bp->b_bufsize, bp->b_kvasize); 1109 } 1110 totalwritten += bp->b_bufsize; 1111 bp->b_dirtyoff = 0; 1112 bp->b_dirtyend = bp->b_bufsize; 1113 bp->b_bio1.bio_done = cluster_callback; 1114 bp->b_cmd = BUF_CMD_WRITE; 1115 1116 vfs_busy_pages(vp, bp); 1117 bsetrunningbufspace(bp, bp->b_bufsize); 1118 BUF_KERNPROC(bp); 1119 vn_strategy(vp, &bp->b_bio1); 1120 1121 bytes -= i; 1122 } 1123 return totalwritten; 1124 } 1125 1126 /* 1127 * Collect together all the buffers in a cluster. 1128 * Plus add one additional buffer. 1129 */ 1130 static struct cluster_save * 1131 cluster_collectbufs(struct vnode *vp, struct buf *last_bp, int blksize) 1132 { 1133 struct cluster_save *buflist; 1134 struct buf *bp; 1135 off_t loffset; 1136 int i, len; 1137 1138 len = (int)(vp->v_lastw - vp->v_cstart + blksize) / blksize; 1139 buflist = kmalloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist), 1140 M_SEGMENT, M_WAITOK); 1141 buflist->bs_nchildren = 0; 1142 buflist->bs_children = (struct buf **) (buflist + 1); 1143 for (loffset = vp->v_cstart, i = 0; i < len; (loffset += blksize), i++) { 1144 (void) bread(vp, loffset, last_bp->b_bcount, &bp); 1145 buflist->bs_children[i] = bp; 1146 if (bp->b_bio2.bio_offset == NOOFFSET) { 1147 VOP_BMAP(bp->b_vp, bp->b_loffset, 1148 &bp->b_bio2.bio_offset, 1149 NULL, NULL, BUF_CMD_WRITE); 1150 } 1151 } 1152 buflist->bs_children[i] = bp = last_bp; 1153 if (bp->b_bio2.bio_offset == NOOFFSET) { 1154 VOP_BMAP(bp->b_vp, bp->b_loffset, &bp->b_bio2.bio_offset, 1155 NULL, NULL, BUF_CMD_WRITE); 1156 } 1157 buflist->bs_nchildren = i + 1; 1158 return (buflist); 1159 } 1160 1161 void 1162 cluster_append(struct bio *bio, struct buf *tbp) 1163 { 1164 tbp->b_cluster_next = NULL; 1165 if (bio->bio_caller_info1.cluster_head == NULL) { 1166 bio->bio_caller_info1.cluster_head = tbp; 1167 bio->bio_caller_info2.cluster_tail = tbp; 1168 } else { 1169 bio->bio_caller_info2.cluster_tail->b_cluster_next = tbp; 1170 bio->bio_caller_info2.cluster_tail = tbp; 1171 } 1172 } 1173 1174 static 1175 void 1176 cluster_setram (struct buf *bp) 1177 { 1178 bp->b_flags |= B_RAM; 1179 if (bp->b_xio.xio_npages) 1180 vm_page_flag_set(bp->b_xio.xio_pages[0], PG_RAM); 1181 } 1182