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 quad_t write_behind_minfilesize = 10 * 1024 * 1024; 86 SYSCTL_QUAD(_vfs, OID_AUTO, write_behind_minfilesize, CTLFLAG_RW, 87 &write_behind_minfilesize, 0, "Cluster write-behind setting"); 88 static int max_readahead = 2 * 1024 * 1024; 89 SYSCTL_INT(_vfs, OID_AUTO, max_readahead, CTLFLAG_RW, &max_readahead, 0, 90 "Limit in bytes for desired cluster read-ahead"); 91 92 extern vm_page_t bogus_page; 93 94 extern int cluster_pbuf_freecnt; 95 96 /* 97 * This replaces bread. 98 * 99 * filesize - read-ahead @ blksize will not cross this boundary 100 * loffset - loffset for returned *bpp 101 * blksize - blocksize for returned *bpp and read-ahead bps 102 * minreq - minimum (not a hard minimum) in bytes, typically reflects 103 * a higher level uio resid. 104 * maxreq - maximum (sequential heuristic) in bytes (highet typ ~2MB) 105 * bpp - return buffer (*bpp) for (loffset,blksize) 106 */ 107 int 108 cluster_readx(struct vnode *vp, off_t filesize, off_t loffset, 109 int blksize, size_t minreq, size_t maxreq, struct buf **bpp) 110 { 111 struct buf *bp, *rbp, *reqbp; 112 off_t origoffset; 113 off_t doffset; 114 int error; 115 int i; 116 int maxra; 117 int maxrbuild; 118 119 error = 0; 120 121 /* 122 * Calculate the desired read-ahead in blksize'd blocks (maxra). 123 * To do this we calculate maxreq. 124 * 125 * maxreq typically starts out as a sequential heuristic. If the 126 * high level uio/resid is bigger (minreq), we pop maxreq up to 127 * minreq. This represents the case where random I/O is being 128 * performed by the userland is issuing big read()'s. 129 * 130 * Then we limit maxreq to max_readahead to ensure it is a reasonable 131 * value. 132 * 133 * Finally we must ensure that (loffset + maxreq) does not cross the 134 * boundary (filesize) for the current blocksize. If we allowed it 135 * to cross we could end up with buffers past the boundary with the 136 * wrong block size (HAMMER large-data areas use mixed block sizes). 137 * minreq is also absolutely limited to filesize. 138 */ 139 if (maxreq < minreq) 140 maxreq = minreq; 141 /* minreq not used beyond this point */ 142 143 if (maxreq > max_readahead) { 144 maxreq = max_readahead; 145 if (maxreq > 16 * 1024 * 1024) 146 maxreq = 16 * 1024 * 1024; 147 } 148 if (maxreq < blksize) 149 maxreq = blksize; 150 if (loffset + maxreq > filesize) { 151 if (loffset > filesize) 152 maxreq = 0; 153 else 154 maxreq = filesize - loffset; 155 } 156 157 maxra = (int)(maxreq / blksize); 158 159 /* 160 * Get the requested block. 161 */ 162 if (*bpp) 163 reqbp = bp = *bpp; 164 else 165 *bpp = reqbp = bp = getblk(vp, loffset, blksize, 0, 0); 166 origoffset = loffset; 167 168 /* 169 * Calculate the maximum cluster size for a single I/O, used 170 * by cluster_rbuild(). 171 */ 172 maxrbuild = vmaxiosize(vp) / blksize; 173 174 /* 175 * if it is in the cache, then check to see if the reads have been 176 * sequential. If they have, then try some read-ahead, otherwise 177 * back-off on prospective read-aheads. 178 */ 179 if (bp->b_flags & B_CACHE) { 180 /* 181 * Not sequential, do not do any read-ahead 182 */ 183 if (maxra <= 1) 184 return 0; 185 186 /* 187 * No read-ahead mark, do not do any read-ahead 188 * yet. 189 */ 190 if ((bp->b_flags & B_RAM) == 0) 191 return 0; 192 193 /* 194 * We hit a read-ahead-mark, figure out how much read-ahead 195 * to do (maxra) and where to start (loffset). 196 * 197 * Shortcut the scan. Typically the way this works is that 198 * we've built up all the blocks inbetween except for the 199 * last in previous iterations, so if the second-to-last 200 * block is present we just skip ahead to it. 201 * 202 * This algorithm has O(1) cpu in the steady state no 203 * matter how large maxra is. 204 */ 205 bp->b_flags &= ~B_RAM; 206 207 if (findblk(vp, loffset + (maxra - 2) * blksize, FINDBLK_TEST)) 208 i = maxra - 1; 209 else 210 i = 1; 211 while (i < maxra) { 212 if (findblk(vp, loffset + i * blksize, 213 FINDBLK_TEST) == NULL) { 214 break; 215 } 216 ++i; 217 } 218 219 /* 220 * We got everything or everything is in the cache, no 221 * point continuing. 222 */ 223 if (i >= maxra) 224 return 0; 225 226 /* 227 * Calculate where to start the read-ahead and how much 228 * to do. Generally speaking we want to read-ahead by 229 * (maxra) when we've found a read-ahead mark. We do 230 * not want to reduce maxra here as it will cause 231 * successive read-ahead I/O's to be smaller and smaller. 232 * 233 * However, we have to make sure we don't break the 234 * filesize limitation for the clustered operation. 235 */ 236 loffset += i * blksize; 237 reqbp = bp = NULL; 238 239 if (loffset >= filesize) 240 return 0; 241 if (loffset + maxra * blksize > filesize) { 242 maxreq = filesize - loffset; 243 maxra = (int)(maxreq / blksize); 244 } 245 } else { 246 __debugvar off_t firstread = bp->b_loffset; 247 int nblks; 248 249 /* 250 * Set-up synchronous read for bp. 251 */ 252 bp->b_cmd = BUF_CMD_READ; 253 bp->b_bio1.bio_done = biodone_sync; 254 bp->b_bio1.bio_flags |= BIO_SYNC; 255 256 KASSERT(firstread != NOOFFSET, 257 ("cluster_read: no buffer offset")); 258 259 /* 260 * nblks is our cluster_rbuild request size, limited 261 * primarily by the device. 262 */ 263 if ((nblks = maxra) > maxrbuild) 264 nblks = maxrbuild; 265 266 if (nblks > 1) { 267 int burstbytes; 268 269 error = VOP_BMAP(vp, loffset, &doffset, 270 &burstbytes, NULL, BUF_CMD_READ); 271 if (error) 272 goto single_block_read; 273 if (nblks > burstbytes / blksize) 274 nblks = burstbytes / blksize; 275 if (doffset == NOOFFSET) 276 goto single_block_read; 277 if (nblks <= 1) 278 goto single_block_read; 279 280 bp = cluster_rbuild(vp, filesize, loffset, 281 doffset, blksize, nblks, bp); 282 loffset += bp->b_bufsize; 283 maxra -= bp->b_bufsize / blksize; 284 } else { 285 single_block_read: 286 /* 287 * If it isn't in the cache, then get a chunk from 288 * disk if sequential, otherwise just get the block. 289 */ 290 cluster_setram(bp); 291 loffset += blksize; 292 --maxra; 293 } 294 } 295 296 /* 297 * If B_CACHE was not set issue bp. bp will either be an 298 * asynchronous cluster buf or a synchronous single-buf. 299 * If it is a single buf it will be the same as reqbp. 300 * 301 * NOTE: Once an async cluster buf is issued bp becomes invalid. 302 */ 303 if (bp) { 304 #if defined(CLUSTERDEBUG) 305 if (rcluster) 306 kprintf("S(%012jx,%d,%d)\n", 307 (intmax_t)bp->b_loffset, bp->b_bcount, maxra); 308 #endif 309 if ((bp->b_flags & B_CLUSTER) == 0) 310 vfs_busy_pages(vp, bp); 311 bp->b_flags &= ~(B_ERROR|B_INVAL); 312 vn_strategy(vp, &bp->b_bio1); 313 error = 0; 314 /* bp invalid now */ 315 } 316 317 /* 318 * If we have been doing sequential I/O, then do some read-ahead. 319 * The code above us should have positioned us at the next likely 320 * offset. 321 * 322 * Only mess with buffers which we can immediately lock. HAMMER 323 * will do device-readahead irrespective of what the blocks 324 * represent. 325 */ 326 while (error == 0 && maxra > 0) { 327 int burstbytes; 328 int tmp_error; 329 int nblks; 330 331 rbp = getblk(vp, loffset, blksize, 332 GETBLK_SZMATCH|GETBLK_NOWAIT, 0); 333 if (rbp == NULL) 334 goto no_read_ahead; 335 if ((rbp->b_flags & B_CACHE)) { 336 bqrelse(rbp); 337 goto no_read_ahead; 338 } 339 340 /* 341 * An error from the read-ahead bmap has nothing to do 342 * with the caller's original request. 343 */ 344 tmp_error = VOP_BMAP(vp, loffset, &doffset, 345 &burstbytes, NULL, BUF_CMD_READ); 346 if (tmp_error || doffset == NOOFFSET) { 347 rbp->b_flags |= B_INVAL; 348 brelse(rbp); 349 rbp = NULL; 350 goto no_read_ahead; 351 } 352 if ((nblks = maxra) > maxrbuild) 353 nblks = maxrbuild; 354 if (nblks > burstbytes / blksize) 355 nblks = burstbytes / blksize; 356 357 /* 358 * rbp: async read 359 */ 360 rbp->b_cmd = BUF_CMD_READ; 361 /*rbp->b_flags |= B_AGE*/; 362 cluster_setram(rbp); 363 364 if (nblks > 1) { 365 rbp = cluster_rbuild(vp, filesize, loffset, 366 doffset, blksize, 367 nblks, rbp); 368 } else { 369 rbp->b_bio2.bio_offset = doffset; 370 } 371 372 #if defined(CLUSTERDEBUG) 373 if (rcluster) { 374 if (bp) { 375 kprintf("A+(%012jx,%d,%jd) " 376 "doff=%012jx minr=%zd ra=%d\n", 377 (intmax_t)loffset, rbp->b_bcount, 378 (intmax_t)(loffset - origoffset), 379 (intmax_t)doffset, minreq, maxra); 380 } else { 381 kprintf("A-(%012jx,%d,%jd) " 382 "doff=%012jx minr=%zd ra=%d\n", 383 (intmax_t)rbp->b_loffset, rbp->b_bcount, 384 (intmax_t)(loffset - origoffset), 385 (intmax_t)doffset, minreq, maxra); 386 } 387 } 388 #endif 389 rbp->b_flags &= ~(B_ERROR|B_INVAL); 390 391 if ((rbp->b_flags & B_CLUSTER) == 0) 392 vfs_busy_pages(vp, rbp); 393 BUF_KERNPROC(rbp); 394 loffset += rbp->b_bufsize; 395 maxra -= rbp->b_bufsize / blksize; 396 vn_strategy(vp, &rbp->b_bio1); 397 /* rbp invalid now */ 398 } 399 400 /* 401 * Wait for our original buffer to complete its I/O. reqbp will 402 * be NULL if the original buffer was B_CACHE. We are returning 403 * (*bpp) which is the same as reqbp when reqbp != NULL. 404 */ 405 no_read_ahead: 406 if (reqbp) { 407 KKASSERT(reqbp->b_bio1.bio_flags & BIO_SYNC); 408 error = biowait(&reqbp->b_bio1, "clurd"); 409 } 410 return (error); 411 } 412 413 /* 414 * If blocks are contiguous on disk, use this to provide clustered 415 * read ahead. We will read as many blocks as possible sequentially 416 * and then parcel them up into logical blocks in the buffer hash table. 417 * 418 * This function either returns a cluster buf or it returns fbp. fbp is 419 * already expected to be set up as a synchronous or asynchronous request. 420 * 421 * If a cluster buf is returned it will always be async. 422 */ 423 static struct buf * 424 cluster_rbuild(struct vnode *vp, off_t filesize, off_t loffset, off_t doffset, 425 int blksize, int run, struct buf *fbp) 426 { 427 struct buf *bp, *tbp; 428 off_t boffset; 429 int i, j; 430 int maxiosize = vmaxiosize(vp); 431 432 /* 433 * avoid a division 434 */ 435 while (loffset + run * blksize > filesize) { 436 --run; 437 } 438 439 tbp = fbp; 440 tbp->b_bio2.bio_offset = doffset; 441 if((tbp->b_flags & B_MALLOC) || 442 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1)) { 443 return tbp; 444 } 445 446 bp = trypbuf_kva(&cluster_pbuf_freecnt); 447 if (bp == NULL) { 448 return tbp; 449 } 450 451 /* 452 * We are synthesizing a buffer out of vm_page_t's, but 453 * if the block size is not page aligned then the starting 454 * address may not be either. Inherit the b_data offset 455 * from the original buffer. 456 */ 457 bp->b_data = (char *)((vm_offset_t)bp->b_data | 458 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 459 bp->b_flags |= B_CLUSTER | B_VMIO; 460 bp->b_cmd = BUF_CMD_READ; 461 bp->b_bio1.bio_done = cluster_callback; /* default to async */ 462 bp->b_bio1.bio_caller_info1.cluster_head = NULL; 463 bp->b_bio1.bio_caller_info2.cluster_tail = NULL; 464 bp->b_loffset = loffset; 465 bp->b_bio2.bio_offset = doffset; 466 KASSERT(bp->b_loffset != NOOFFSET, 467 ("cluster_rbuild: no buffer offset")); 468 469 bp->b_bcount = 0; 470 bp->b_bufsize = 0; 471 bp->b_xio.xio_npages = 0; 472 473 for (boffset = doffset, i = 0; i < run; ++i, boffset += blksize) { 474 if (i) { 475 if ((bp->b_xio.xio_npages * PAGE_SIZE) + 476 round_page(blksize) > maxiosize) { 477 break; 478 } 479 480 /* 481 * Shortcut some checks and try to avoid buffers that 482 * would block in the lock. The same checks have to 483 * be made again after we officially get the buffer. 484 */ 485 tbp = getblk(vp, loffset + i * blksize, blksize, 486 GETBLK_SZMATCH|GETBLK_NOWAIT, 0); 487 if (tbp == NULL) 488 break; 489 for (j = 0; j < tbp->b_xio.xio_npages; j++) { 490 if (tbp->b_xio.xio_pages[j]->valid) 491 break; 492 } 493 if (j != tbp->b_xio.xio_npages) { 494 bqrelse(tbp); 495 break; 496 } 497 498 /* 499 * Stop scanning if the buffer is fuly valid 500 * (marked B_CACHE), or locked (may be doing a 501 * background write), or if the buffer is not 502 * VMIO backed. The clustering code can only deal 503 * with VMIO-backed buffers. 504 */ 505 if ((tbp->b_flags & (B_CACHE|B_LOCKED)) || 506 (tbp->b_flags & B_VMIO) == 0 || 507 (LIST_FIRST(&tbp->b_dep) != NULL && 508 buf_checkread(tbp)) 509 ) { 510 bqrelse(tbp); 511 break; 512 } 513 514 /* 515 * The buffer must be completely invalid in order to 516 * take part in the cluster. If it is partially valid 517 * then we stop. 518 */ 519 for (j = 0;j < tbp->b_xio.xio_npages; j++) { 520 if (tbp->b_xio.xio_pages[j]->valid) 521 break; 522 } 523 if (j != tbp->b_xio.xio_npages) { 524 bqrelse(tbp); 525 break; 526 } 527 528 /* 529 * Set a read-ahead mark as appropriate. Always 530 * set the read-ahead mark at (run - 1). It is 531 * unclear why we were also setting it at i == 1. 532 */ 533 if (/*i == 1 ||*/ i == (run - 1)) 534 cluster_setram(tbp); 535 536 /* 537 * Depress the priority of buffers not explicitly 538 * requested. 539 */ 540 /* tbp->b_flags |= B_AGE; */ 541 542 /* 543 * Set the block number if it isn't set, otherwise 544 * if it is make sure it matches the block number we 545 * expect. 546 */ 547 if (tbp->b_bio2.bio_offset == NOOFFSET) { 548 tbp->b_bio2.bio_offset = boffset; 549 } else if (tbp->b_bio2.bio_offset != boffset) { 550 brelse(tbp); 551 break; 552 } 553 } 554 555 /* 556 * The passed-in tbp (i == 0) will already be set up for 557 * async or sync operation. All other tbp's acquire in 558 * our loop are set up for async operation. 559 */ 560 tbp->b_cmd = BUF_CMD_READ; 561 BUF_KERNPROC(tbp); 562 cluster_append(&bp->b_bio1, tbp); 563 for (j = 0; j < tbp->b_xio.xio_npages; ++j) { 564 vm_page_t m; 565 566 m = tbp->b_xio.xio_pages[j]; 567 vm_page_busy_wait(m, FALSE, "clurpg"); 568 vm_page_io_start(m); 569 vm_page_wakeup(m); 570 vm_object_pip_add(m->object, 1); 571 if ((bp->b_xio.xio_npages == 0) || 572 (bp->b_xio.xio_pages[bp->b_xio.xio_npages-1] != m)) { 573 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 574 bp->b_xio.xio_npages++; 575 } 576 if ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) 577 tbp->b_xio.xio_pages[j] = bogus_page; 578 } 579 /* 580 * XXX shouldn't this be += size for both, like in 581 * cluster_wbuild()? 582 * 583 * Don't inherit tbp->b_bufsize as it may be larger due to 584 * a non-page-aligned size. Instead just aggregate using 585 * 'size'. 586 */ 587 if (tbp->b_bcount != blksize) 588 kprintf("warning: tbp->b_bcount wrong %d vs %d\n", tbp->b_bcount, blksize); 589 if (tbp->b_bufsize != blksize) 590 kprintf("warning: tbp->b_bufsize wrong %d vs %d\n", tbp->b_bufsize, blksize); 591 bp->b_bcount += blksize; 592 bp->b_bufsize += blksize; 593 } 594 595 /* 596 * Fully valid pages in the cluster are already good and do not need 597 * to be re-read from disk. Replace the page with bogus_page 598 */ 599 for (j = 0; j < bp->b_xio.xio_npages; j++) { 600 if ((bp->b_xio.xio_pages[j]->valid & VM_PAGE_BITS_ALL) == 601 VM_PAGE_BITS_ALL) { 602 bp->b_xio.xio_pages[j] = bogus_page; 603 } 604 } 605 if (bp->b_bufsize > bp->b_kvasize) { 606 panic("cluster_rbuild: b_bufsize(%d) > b_kvasize(%d)", 607 bp->b_bufsize, bp->b_kvasize); 608 } 609 pmap_qenter(trunc_page((vm_offset_t) bp->b_data), 610 (vm_page_t *)bp->b_xio.xio_pages, bp->b_xio.xio_npages); 611 BUF_KERNPROC(bp); 612 return (bp); 613 } 614 615 /* 616 * Cleanup after a clustered read or write. 617 * This is complicated by the fact that any of the buffers might have 618 * extra memory (if there were no empty buffer headers at allocbuf time) 619 * that we will need to shift around. 620 * 621 * The returned bio is &bp->b_bio1 622 */ 623 void 624 cluster_callback(struct bio *bio) 625 { 626 struct buf *bp = bio->bio_buf; 627 struct buf *tbp; 628 int error = 0; 629 630 /* 631 * Must propogate errors to all the components. A short read (EOF) 632 * is a critical error. 633 */ 634 if (bp->b_flags & B_ERROR) { 635 error = bp->b_error; 636 } else if (bp->b_bcount != bp->b_bufsize) { 637 panic("cluster_callback: unexpected EOF on cluster %p!", bio); 638 } 639 640 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_xio.xio_npages); 641 /* 642 * Move memory from the large cluster buffer into the component 643 * buffers and mark IO as done on these. Since the memory map 644 * is the same, no actual copying is required. 645 */ 646 while ((tbp = bio->bio_caller_info1.cluster_head) != NULL) { 647 bio->bio_caller_info1.cluster_head = tbp->b_cluster_next; 648 if (error) { 649 tbp->b_flags |= B_ERROR | B_IODEBUG; 650 tbp->b_error = error; 651 } else { 652 tbp->b_dirtyoff = tbp->b_dirtyend = 0; 653 tbp->b_flags &= ~(B_ERROR|B_INVAL); 654 tbp->b_flags |= B_IODEBUG; 655 /* 656 * XXX the bdwrite()/bqrelse() issued during 657 * cluster building clears B_RELBUF (see bqrelse() 658 * comment). If direct I/O was specified, we have 659 * to restore it here to allow the buffer and VM 660 * to be freed. 661 */ 662 if (tbp->b_flags & B_DIRECT) 663 tbp->b_flags |= B_RELBUF; 664 } 665 biodone(&tbp->b_bio1); 666 } 667 relpbuf(bp, &cluster_pbuf_freecnt); 668 } 669 670 /* 671 * Implement modified write build for cluster. 672 * 673 * write_behind = 0 write behind disabled 674 * write_behind = 1 write behind normal (default) 675 * write_behind = 2 write behind backed-off 676 * 677 * In addition, write_behind is only activated for files that have 678 * grown past a certain size (default 10MB). Otherwise temporary files 679 * wind up generating a lot of unnecessary disk I/O. 680 */ 681 static __inline int 682 cluster_wbuild_wb(struct vnode *vp, int blksize, off_t start_loffset, int len) 683 { 684 int r = 0; 685 686 switch(write_behind) { 687 case 2: 688 if (start_loffset < len) 689 break; 690 start_loffset -= len; 691 /* fall through */ 692 case 1: 693 if (vp->v_filesize >= write_behind_minfilesize) { 694 r = cluster_wbuild(vp, NULL, blksize, 695 start_loffset, len); 696 } 697 /* fall through */ 698 default: 699 /* fall through */ 700 break; 701 } 702 return(r); 703 } 704 705 /* 706 * Do clustered write for FFS. 707 * 708 * Three cases: 709 * 1. Write is not sequential (write asynchronously) 710 * Write is sequential: 711 * 2. beginning of cluster - begin cluster 712 * 3. middle of a cluster - add to cluster 713 * 4. end of a cluster - asynchronously write cluster 714 */ 715 void 716 cluster_write(struct buf *bp, off_t filesize, int blksize, int seqcount) 717 { 718 struct vnode *vp; 719 off_t loffset; 720 int maxclen, cursize; 721 int async; 722 723 vp = bp->b_vp; 724 if (vp->v_type == VREG) 725 async = vp->v_mount->mnt_flag & MNT_ASYNC; 726 else 727 async = 0; 728 loffset = bp->b_loffset; 729 KASSERT(bp->b_loffset != NOOFFSET, 730 ("cluster_write: no buffer offset")); 731 732 /* Initialize vnode to beginning of file. */ 733 if (loffset == 0) 734 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0; 735 736 if (vp->v_clen == 0 || loffset != vp->v_lastw + blksize || 737 bp->b_bio2.bio_offset == NOOFFSET || 738 (bp->b_bio2.bio_offset != vp->v_lasta + blksize)) { 739 maxclen = vmaxiosize(vp); 740 if (vp->v_clen != 0) { 741 /* 742 * Next block is not sequential. 743 * 744 * If we are not writing at end of file, the process 745 * seeked to another point in the file since its last 746 * write, or we have reached our maximum cluster size, 747 * then push the previous cluster. Otherwise try 748 * reallocating to make it sequential. 749 * 750 * Change to algorithm: only push previous cluster if 751 * it was sequential from the point of view of the 752 * seqcount heuristic, otherwise leave the buffer 753 * intact so we can potentially optimize the I/O 754 * later on in the buf_daemon or update daemon 755 * flush. 756 */ 757 cursize = vp->v_lastw - vp->v_cstart + blksize; 758 if (bp->b_loffset + blksize < filesize || 759 loffset != vp->v_lastw + blksize || vp->v_clen <= cursize) { 760 if (!async && seqcount > 0) { 761 cluster_wbuild_wb(vp, blksize, 762 vp->v_cstart, cursize); 763 } 764 } else { 765 struct buf **bpp, **endbp; 766 struct cluster_save *buflist; 767 768 buflist = cluster_collectbufs(vp, bp, blksize); 769 endbp = &buflist->bs_children 770 [buflist->bs_nchildren - 1]; 771 if (VOP_REALLOCBLKS(vp, buflist)) { 772 /* 773 * Failed, push the previous cluster 774 * if *really* writing sequentially 775 * in the logical file (seqcount > 1), 776 * otherwise delay it in the hopes that 777 * the low level disk driver can 778 * optimize the write ordering. 779 */ 780 for (bpp = buflist->bs_children; 781 bpp < endbp; bpp++) 782 brelse(*bpp); 783 kfree(buflist, M_SEGMENT); 784 if (seqcount > 1) { 785 cluster_wbuild_wb(vp, 786 blksize, vp->v_cstart, 787 cursize); 788 } 789 } else { 790 /* 791 * Succeeded, keep building cluster. 792 */ 793 for (bpp = buflist->bs_children; 794 bpp <= endbp; bpp++) 795 bdwrite(*bpp); 796 kfree(buflist, M_SEGMENT); 797 vp->v_lastw = loffset; 798 vp->v_lasta = bp->b_bio2.bio_offset; 799 return; 800 } 801 } 802 } 803 /* 804 * Consider beginning a cluster. If at end of file, make 805 * cluster as large as possible, otherwise find size of 806 * existing cluster. 807 */ 808 if ((vp->v_type == VREG) && 809 bp->b_loffset + blksize < filesize && 810 (bp->b_bio2.bio_offset == NOOFFSET) && 811 (VOP_BMAP(vp, loffset, &bp->b_bio2.bio_offset, &maxclen, NULL, BUF_CMD_WRITE) || 812 bp->b_bio2.bio_offset == NOOFFSET)) { 813 bdwrite(bp); 814 vp->v_clen = 0; 815 vp->v_lasta = bp->b_bio2.bio_offset; 816 vp->v_cstart = loffset + blksize; 817 vp->v_lastw = loffset; 818 return; 819 } 820 if (maxclen > blksize) 821 vp->v_clen = maxclen - blksize; 822 else 823 vp->v_clen = 0; 824 if (!async && vp->v_clen == 0) { /* I/O not contiguous */ 825 vp->v_cstart = loffset + blksize; 826 bdwrite(bp); 827 } else { /* Wait for rest of cluster */ 828 vp->v_cstart = loffset; 829 bdwrite(bp); 830 } 831 } else if (loffset == vp->v_cstart + vp->v_clen) { 832 /* 833 * At end of cluster, write it out if seqcount tells us we 834 * are operating sequentially, otherwise let the buf or 835 * update daemon handle it. 836 */ 837 bdwrite(bp); 838 if (seqcount > 1) 839 cluster_wbuild_wb(vp, blksize, vp->v_cstart, 840 vp->v_clen + blksize); 841 vp->v_clen = 0; 842 vp->v_cstart = loffset + blksize; 843 } else if (vm_page_count_severe() && 844 bp->b_loffset + blksize < filesize) { 845 /* 846 * We are low on memory, get it going NOW. However, do not 847 * try to push out a partial block at the end of the file 848 * as this could lead to extremely non-optimal write activity. 849 */ 850 bawrite(bp); 851 } else { 852 /* 853 * In the middle of a cluster, so just delay the I/O for now. 854 */ 855 bdwrite(bp); 856 } 857 vp->v_lastw = loffset; 858 vp->v_lasta = bp->b_bio2.bio_offset; 859 } 860 861 /* 862 * This is the clustered version of bawrite(). It works similarly to 863 * cluster_write() except I/O on the buffer is guaranteed to occur. 864 */ 865 int 866 cluster_awrite(struct buf *bp) 867 { 868 int total; 869 870 /* 871 * Don't bother if it isn't clusterable. 872 */ 873 if ((bp->b_flags & B_CLUSTEROK) == 0 || 874 bp->b_vp == NULL || 875 (bp->b_vp->v_flag & VOBJBUF) == 0) { 876 total = bp->b_bufsize; 877 bawrite(bp); 878 return (total); 879 } 880 881 total = cluster_wbuild(bp->b_vp, &bp, bp->b_bufsize, 882 bp->b_loffset, vmaxiosize(bp->b_vp)); 883 if (bp) 884 bawrite(bp); 885 886 return total; 887 } 888 889 /* 890 * This is an awful lot like cluster_rbuild...wish they could be combined. 891 * The last lbn argument is the current block on which I/O is being 892 * performed. Check to see that it doesn't fall in the middle of 893 * the current block (if last_bp == NULL). 894 * 895 * cluster_wbuild() normally does not guarantee anything. If bpp is 896 * non-NULL and cluster_wbuild() is able to incorporate it into the 897 * I/O it will set *bpp to NULL, otherwise it will leave it alone and 898 * the caller must dispose of *bpp. 899 */ 900 static int 901 cluster_wbuild(struct vnode *vp, struct buf **bpp, 902 int blksize, off_t start_loffset, int bytes) 903 { 904 struct buf *bp, *tbp; 905 int i, j; 906 int totalwritten = 0; 907 int must_initiate; 908 int maxiosize = vmaxiosize(vp); 909 910 while (bytes > 0) { 911 /* 912 * If the buffer matches the passed locked & removed buffer 913 * we used the passed buffer (which might not be B_DELWRI). 914 * 915 * Otherwise locate the buffer and determine if it is 916 * compatible. 917 */ 918 if (bpp && (*bpp)->b_loffset == start_loffset) { 919 tbp = *bpp; 920 *bpp = NULL; 921 bpp = NULL; 922 } else { 923 tbp = findblk(vp, start_loffset, FINDBLK_NBLOCK); 924 if (tbp == NULL || 925 (tbp->b_flags & (B_LOCKED | B_INVAL | B_DELWRI)) != 926 B_DELWRI || 927 (LIST_FIRST(&tbp->b_dep) && buf_checkwrite(tbp))) { 928 if (tbp) 929 BUF_UNLOCK(tbp); 930 start_loffset += blksize; 931 bytes -= blksize; 932 continue; 933 } 934 bremfree(tbp); 935 } 936 KKASSERT(tbp->b_cmd == BUF_CMD_DONE); 937 938 /* 939 * Extra memory in the buffer, punt on this buffer. 940 * XXX we could handle this in most cases, but we would 941 * have to push the extra memory down to after our max 942 * possible cluster size and then potentially pull it back 943 * up if the cluster was terminated prematurely--too much 944 * hassle. 945 */ 946 if (((tbp->b_flags & (B_CLUSTEROK|B_MALLOC)) != B_CLUSTEROK) || 947 (tbp->b_bcount != tbp->b_bufsize) || 948 (tbp->b_bcount != blksize) || 949 (bytes == blksize) || 950 ((bp = getpbuf_kva(&cluster_pbuf_freecnt)) == NULL)) { 951 totalwritten += tbp->b_bufsize; 952 bawrite(tbp); 953 start_loffset += blksize; 954 bytes -= blksize; 955 continue; 956 } 957 958 /* 959 * Set up the pbuf. Track our append point with b_bcount 960 * and b_bufsize. b_bufsize is not used by the device but 961 * our caller uses it to loop clusters and we use it to 962 * detect a premature EOF on the block device. 963 */ 964 bp->b_bcount = 0; 965 bp->b_bufsize = 0; 966 bp->b_xio.xio_npages = 0; 967 bp->b_loffset = tbp->b_loffset; 968 bp->b_bio2.bio_offset = tbp->b_bio2.bio_offset; 969 970 /* 971 * We are synthesizing a buffer out of vm_page_t's, but 972 * if the block size is not page aligned then the starting 973 * address may not be either. Inherit the b_data offset 974 * from the original buffer. 975 */ 976 bp->b_data = (char *)((vm_offset_t)bp->b_data | 977 ((vm_offset_t)tbp->b_data & PAGE_MASK)); 978 bp->b_flags &= ~B_ERROR; 979 bp->b_flags |= B_CLUSTER | B_BNOCLIP | 980 (tbp->b_flags & (B_VMIO | B_NEEDCOMMIT)); 981 bp->b_bio1.bio_caller_info1.cluster_head = NULL; 982 bp->b_bio1.bio_caller_info2.cluster_tail = NULL; 983 984 /* 985 * From this location in the file, scan forward to see 986 * if there are buffers with adjacent data that need to 987 * be written as well. 988 * 989 * IO *must* be initiated on index 0 at this point 990 * (particularly when called from cluster_awrite()). 991 */ 992 for (i = 0; i < bytes; (i += blksize), (start_loffset += blksize)) { 993 if (i == 0) { 994 must_initiate = 1; 995 } else { 996 /* 997 * Not first buffer. 998 */ 999 must_initiate = 0; 1000 tbp = findblk(vp, start_loffset, 1001 FINDBLK_NBLOCK); 1002 /* 1003 * Buffer not found or could not be locked 1004 * non-blocking. 1005 */ 1006 if (tbp == NULL) 1007 break; 1008 1009 /* 1010 * If it IS in core, but has different 1011 * characteristics, then don't cluster 1012 * with it. 1013 */ 1014 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK | 1015 B_INVAL | B_DELWRI | B_NEEDCOMMIT)) 1016 != (B_DELWRI | B_CLUSTEROK | 1017 (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) || 1018 (tbp->b_flags & B_LOCKED) 1019 ) { 1020 BUF_UNLOCK(tbp); 1021 break; 1022 } 1023 1024 /* 1025 * Check that the combined cluster 1026 * would make sense with regard to pages 1027 * and would not be too large 1028 * 1029 * WARNING! buf_checkwrite() must be the last 1030 * check made. If it returns 0 then 1031 * we must initiate the I/O. 1032 */ 1033 if ((tbp->b_bcount != blksize) || 1034 ((bp->b_bio2.bio_offset + i) != 1035 tbp->b_bio2.bio_offset) || 1036 ((tbp->b_xio.xio_npages + bp->b_xio.xio_npages) > 1037 (maxiosize / PAGE_SIZE)) || 1038 (LIST_FIRST(&tbp->b_dep) && 1039 buf_checkwrite(tbp)) 1040 ) { 1041 BUF_UNLOCK(tbp); 1042 break; 1043 } 1044 if (LIST_FIRST(&tbp->b_dep)) 1045 must_initiate = 1; 1046 /* 1047 * Ok, it's passed all the tests, 1048 * so remove it from the free list 1049 * and mark it busy. We will use it. 1050 */ 1051 bremfree(tbp); 1052 KKASSERT(tbp->b_cmd == BUF_CMD_DONE); 1053 } 1054 1055 /* 1056 * If the IO is via the VM then we do some 1057 * special VM hackery (yuck). Since the buffer's 1058 * block size may not be page-aligned it is possible 1059 * for a page to be shared between two buffers. We 1060 * have to get rid of the duplication when building 1061 * the cluster. 1062 */ 1063 if (tbp->b_flags & B_VMIO) { 1064 vm_page_t m; 1065 1066 /* 1067 * Try to avoid deadlocks with the VM system. 1068 * However, we cannot abort the I/O if 1069 * must_initiate is non-zero. 1070 */ 1071 if (must_initiate == 0) { 1072 for (j = 0; 1073 j < tbp->b_xio.xio_npages; 1074 ++j) { 1075 m = tbp->b_xio.xio_pages[j]; 1076 if (m->flags & PG_BUSY) { 1077 bqrelse(tbp); 1078 goto finishcluster; 1079 } 1080 } 1081 } 1082 1083 for (j = 0; j < tbp->b_xio.xio_npages; ++j) { 1084 m = tbp->b_xio.xio_pages[j]; 1085 vm_page_busy_wait(m, FALSE, "clurpg"); 1086 vm_page_io_start(m); 1087 vm_page_wakeup(m); 1088 vm_object_pip_add(m->object, 1); 1089 if ((bp->b_xio.xio_npages == 0) || 1090 (bp->b_xio.xio_pages[bp->b_xio.xio_npages - 1] != m)) { 1091 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; 1092 bp->b_xio.xio_npages++; 1093 } 1094 } 1095 } 1096 bp->b_bcount += blksize; 1097 bp->b_bufsize += blksize; 1098 1099 bundirty(tbp); 1100 tbp->b_flags &= ~B_ERROR; 1101 tbp->b_cmd = BUF_CMD_WRITE; 1102 BUF_KERNPROC(tbp); 1103 cluster_append(&bp->b_bio1, tbp); 1104 1105 /* 1106 * check for latent dependencies to be handled 1107 */ 1108 if (LIST_FIRST(&tbp->b_dep) != NULL) 1109 buf_start(tbp); 1110 } 1111 finishcluster: 1112 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 1113 (vm_page_t *)bp->b_xio.xio_pages, 1114 bp->b_xio.xio_npages); 1115 if (bp->b_bufsize > bp->b_kvasize) { 1116 panic("cluster_wbuild: b_bufsize(%d) " 1117 "> b_kvasize(%d)\n", 1118 bp->b_bufsize, bp->b_kvasize); 1119 } 1120 totalwritten += bp->b_bufsize; 1121 bp->b_dirtyoff = 0; 1122 bp->b_dirtyend = bp->b_bufsize; 1123 bp->b_bio1.bio_done = cluster_callback; 1124 bp->b_cmd = BUF_CMD_WRITE; 1125 1126 vfs_busy_pages(vp, bp); 1127 bsetrunningbufspace(bp, bp->b_bufsize); 1128 BUF_KERNPROC(bp); 1129 vn_strategy(vp, &bp->b_bio1); 1130 1131 bytes -= i; 1132 } 1133 return totalwritten; 1134 } 1135 1136 /* 1137 * Collect together all the buffers in a cluster. 1138 * Plus add one additional buffer. 1139 */ 1140 static struct cluster_save * 1141 cluster_collectbufs(struct vnode *vp, struct buf *last_bp, int blksize) 1142 { 1143 struct cluster_save *buflist; 1144 struct buf *bp; 1145 off_t loffset; 1146 int i, len; 1147 1148 len = (int)(vp->v_lastw - vp->v_cstart + blksize) / blksize; 1149 buflist = kmalloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist), 1150 M_SEGMENT, M_WAITOK); 1151 buflist->bs_nchildren = 0; 1152 buflist->bs_children = (struct buf **) (buflist + 1); 1153 for (loffset = vp->v_cstart, i = 0; i < len; (loffset += blksize), i++) { 1154 (void) bread(vp, loffset, last_bp->b_bcount, &bp); 1155 buflist->bs_children[i] = bp; 1156 if (bp->b_bio2.bio_offset == NOOFFSET) { 1157 VOP_BMAP(bp->b_vp, bp->b_loffset, 1158 &bp->b_bio2.bio_offset, 1159 NULL, NULL, BUF_CMD_WRITE); 1160 } 1161 } 1162 buflist->bs_children[i] = bp = last_bp; 1163 if (bp->b_bio2.bio_offset == NOOFFSET) { 1164 VOP_BMAP(bp->b_vp, bp->b_loffset, &bp->b_bio2.bio_offset, 1165 NULL, NULL, BUF_CMD_WRITE); 1166 } 1167 buflist->bs_nchildren = i + 1; 1168 return (buflist); 1169 } 1170 1171 void 1172 cluster_append(struct bio *bio, struct buf *tbp) 1173 { 1174 tbp->b_cluster_next = NULL; 1175 if (bio->bio_caller_info1.cluster_head == NULL) { 1176 bio->bio_caller_info1.cluster_head = tbp; 1177 bio->bio_caller_info2.cluster_tail = tbp; 1178 } else { 1179 bio->bio_caller_info2.cluster_tail->b_cluster_next = tbp; 1180 bio->bio_caller_info2.cluster_tail = tbp; 1181 } 1182 } 1183 1184 static 1185 void 1186 cluster_setram (struct buf *bp) 1187 { 1188 bp->b_flags |= B_RAM; 1189 if (bp->b_xio.xio_npages) 1190 vm_page_flag_set(bp->b_xio.xio_pages[0], PG_RAM); 1191 } 1192