sys/kern/vfs_cluster.c

   1 /*-
   2  * Copyright (c) 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  * Modifications/enhancements:
   5  *      Copyright (c) 1995 John S. Dyson.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. All advertising materials mentioning features or use of this software
  16  *    must display the following acknowledgement:
  17  *      This product includes software developed by the University of
  18  *      California, Berkeley and its contributors.
  19  * 4. Neither the name of the University nor the names of its contributors
  20  *    may be used to endorse or promote products derived from this software
  21  *    without specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  33  * SUCH DAMAGE.
  34  *
  35  *      @(#)vfs_cluster.c       8.7 (Berkeley) 2/13/94
  36  * $FreeBSD: src/sys/kern/vfs_cluster.c,v 1.92.2.9 2001/11/18 07:10:59 dillon Exp $
  37  * $DragonFly: src/sys/kern/vfs_cluster.c,v 1.40 2008/07/14 03:09:00 dillon Exp $
  38  */
  39
  40 #include "opt_debug_cluster.h"
  41
  42 #include <sys/param.h>
  43 #include <sys/systm.h>
  44 #include <sys/kernel.h>
  45 #include <sys/proc.h>
  46 #include <sys/buf.h>
  47 #include <sys/vnode.h>
  48 #include <sys/malloc.h>
  49 #include <sys/mount.h>
  50 #include <sys/resourcevar.h>
  51 #include <sys/vmmeter.h>
  52 #include <vm/vm.h>
  53 #include <vm/vm_object.h>
  54 #include <vm/vm_page.h>
  55 #include <sys/sysctl.h>
  56 #include <sys/buf2.h>
  57 #include <vm/vm_page2.h>
  58
  59 #include <machine/limits.h>
  60
  61 #if defined(CLUSTERDEBUG)
  62 #include <sys/sysctl.h>
  63 static int      rcluster= 0;
  64 SYSCTL_INT(_debug, OID_AUTO, rcluster, CTLFLAG_RW, &rcluster, 0, "");
  65 #endif
  66
  67 static MALLOC_DEFINE(M_SEGMENT, "cluster_save", "cluster_save buffer");
  68
  69 static struct cluster_save *
  70         cluster_collectbufs (struct vnode *vp, struct buf *last_bp,
  71                             int blksize);
  72 static struct buf *
  73         cluster_rbuild (struct vnode *vp, off_t filesize, off_t loffset,
  74                             off_t doffset, int blksize, int run,
  75                             struct buf *fbp);
  76 static void cluster_callback (struct bio *);
  77 static void cluster_setram (struct buf *);
  78
  79 static int write_behind = 1;
  80 SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0, "");
  81 static int max_readahead = 2 * 1024 * 1024;
  82 SYSCTL_INT(_vfs, OID_AUTO, max_readahead, CTLFLAG_RW, &max_readahead, 0, "");
  83
  84 extern vm_page_t        bogus_page;
  85
  86 extern int cluster_pbuf_freecnt;
  87
  88 /*
  89  * This replaces bread.
  90  *
  91  * filesize     - read-ahead @ blksize will not cross this boundary
  92  * loffset      - loffset for returned *bpp
  93  * blksize      - blocksize for returned *bpp and read-ahead bps
  94  * minreq       - minimum (not a hard minimum) in bytes, typically reflects
  95  *                a higher level uio resid.
  96  * maxreq       - maximum (sequential heuristic) in bytes (highet typ ~2MB)
  97  * bpp          - return buffer (*bpp) for (loffset,blksize)
  98  */
  99 int
 100 cluster_read(struct vnode *vp, off_t filesize, off_t loffset,
 101              int blksize, size_t minreq, size_t maxreq, struct buf **bpp)
 102 {
 103         struct buf *bp, *rbp, *reqbp;
 104         off_t origoffset;
 105         off_t doffset;
 106         int error;
 107         int i;
 108         int maxra;
 109         int maxrbuild;
 110
 111         error = 0;
 112
 113         /*
 114          * Calculate the desired read-ahead in blksize'd blocks (maxra).
 115          * To do this we calculate maxreq.
 116          *
 117          * maxreq typically starts out as a sequential heuristic.  If the
 118          * high level uio/resid is bigger (minreq), we pop maxreq up to
 119          * minreq.  This represents the case where random I/O is being
 120          * performed by the userland is issuing big read()'s.
 121          *
 122          * Then we limit maxreq to max_readahead to ensure it is a reasonable
 123          * value.
 124          *
 125          * Finally we must ensure that loffset + maxreq does not cross the
 126          * boundary (filesize) for the current blocksize.  If we allowed it
 127          * to cross we could end up with buffers past the boundary with the
 128          * wrong block size (HAMMER large-data areas use mixed block sizes).
 129          */
 130         if (maxreq < minreq)
 131                 maxreq = minreq;
 132         if (maxreq > max_readahead) {
 133                 maxreq = max_readahead;
 134                 if (maxreq > 16 * 1024 * 1024)
 135                         maxreq = 16 * 1024 * 1024;
 136         }
 137         if (maxreq < blksize)
 138                 maxreq = blksize;
 139         if (loffset + maxreq > filesize) {
 140                 if (loffset > filesize)
 141                         maxreq = 0;
 142                 else
 143                         maxreq = filesize - loffset;
 144         }
 145
 146         maxra = (int)(maxreq / blksize);
 147
 148         /*
 149          * Get the requested block.
 150          */
 151         *bpp = reqbp = bp = getblk(vp, loffset, blksize, 0, 0);
 152         origoffset = loffset;
 153
 154         /*
 155          * Calculate the maximum cluster size for a single I/O, used
 156          * by cluster_rbuild().
 157          */
 158         maxrbuild = vmaxiosize(vp) / blksize;
 159
 160         /*
 161          * if it is in the cache, then check to see if the reads have been
 162          * sequential.  If they have, then try some read-ahead, otherwise
 163          * back-off on prospective read-aheads.
 164          */
 165         if (bp->b_flags & B_CACHE) {
 166                 /*
 167                  * Not sequential, do not do any read-ahead
 168                  */
 169                 if (maxra <= 1)
 170                         return 0;
 171
 172                 /*
 173                  * No read-ahead mark, do not do any read-ahead
 174                  * yet.
 175                  */
 176                 if ((bp->b_flags & B_RAM) == 0)
 177                         return 0;
 178
 179                 /*
 180                  * We hit a read-ahead-mark, figure out how much read-ahead
 181                  * to do (maxra) and where to start (loffset).
 182                  *
 183                  * Shortcut the scan.  Typically the way this works is that
 184                  * we've built up all the blocks inbetween except for the
 185                  * last in previous iterations, so if the second-to-last
 186                  * block is present we just skip ahead to it.
 187                  *
 188                  * This algorithm has O(1) cpu in the steady state no
 189                  * matter how large maxra is.
 190                  */
 191                 bp->b_flags &= ~B_RAM;
 192
 193                 if (findblk(vp, loffset + (maxra - 2) * blksize, FINDBLK_TEST))
 194                         i = maxra - 1;
 195                 else
 196                         i = 1;
 197                 while (i < maxra) {
 198                         if (findblk(vp, loffset + i * blksize,
 199                                     FINDBLK_TEST) == NULL) {
 200                                 break;
 201                         }
 202                         ++i;
 203                 }
 204
 205                 /*
 206                  * We got everything or everything is in the cache, no
 207                  * point continuing.
 208                  */
 209                 if (i >= maxra)
 210                         return 0;
 211                 maxra -= i;
 212                 loffset += i * blksize;
 213                 reqbp = bp = NULL;
 214         } else {
 215                 __debugvar off_t firstread = bp->b_loffset;
 216                 int nblks;
 217
 218                 /*
 219                  * Set-up synchronous read for bp.
 220                  */
 221                 bp->b_cmd = BUF_CMD_READ;
 222                 bp->b_bio1.bio_done = biodone_sync;
 223                 bp->b_bio1.bio_flags |= BIO_SYNC;
 224
 225                 KASSERT(firstread != NOOFFSET,
 226                         ("cluster_read: no buffer offset"));
 227
 228                 /*
 229                  * nblks is our cluster_rbuild request size, limited
 230                  * primarily by the device.
 231                  */
 232                 if ((nblks = maxra) > maxrbuild)
 233                         nblks = maxrbuild;
 234
 235                 if (nblks > 1) {
 236                         int burstbytes;
 237
 238                         error = VOP_BMAP(vp, loffset, &doffset,
 239                                          &burstbytes, NULL, BUF_CMD_READ);
 240                         if (error)
 241                                 goto single_block_read;
 242                         if (nblks > burstbytes / blksize)
 243                                 nblks = burstbytes / blksize;
 244                         if (doffset == NOOFFSET)
 245                                 goto single_block_read;
 246                         if (nblks <= 1)
 247                                 goto single_block_read;
 248
 249                         bp = cluster_rbuild(vp, filesize, loffset,
 250                                             doffset, blksize, nblks, bp);
 251                         loffset += bp->b_bufsize;
 252                         maxra -= bp->b_bufsize / blksize;
 253                 } else {
 254 single_block_read:
 255                         /*
 256                          * If it isn't in the cache, then get a chunk from
 257                          * disk if sequential, otherwise just get the block.
 258                          */
 259                         cluster_setram(bp);
 260                         loffset += blksize;
 261                         --maxra;
 262                 }
 263         }
 264
 265         /*
 266          * If B_CACHE was not set issue bp.  bp will either be an
 267          * asynchronous cluster buf or a synchronous single-buf.
 268          * If it is a single buf it will be the same as reqbp.
 269          *
 270          * NOTE: Once an async cluster buf is issued bp becomes invalid.
 271          */
 272         if (bp) {
 273 #if defined(CLUSTERDEBUG)
 274                 if (rcluster)
 275                         kprintf("S(%012jx,%d,%d)\n",
 276                             (intmax_t)bp->b_loffset, bp->b_bcount, maxra);
 277 #endif
 278                 if ((bp->b_flags & B_CLUSTER) == 0)
 279                         vfs_busy_pages(vp, bp);
 280                 bp->b_flags &= ~(B_ERROR|B_INVAL);
 281                 vn_strategy(vp, &bp->b_bio1);
 282                 error = 0;
 283                 /* bp invalid now */
 284         }
 285
 286         /*
 287          * If we have been doing sequential I/O, then do some read-ahead.
 288          * The code above us should have positioned us at the next likely
 289          * offset.
 290          *
 291          * Only mess with buffers which we can immediately lock.  HAMMER
 292          * will do device-readahead irrespective of what the blocks
 293          * represent.
 294          */
 295         while (error == 0 && maxra > 0) {
 296                 int burstbytes;
 297                 int tmp_error;
 298                 int nblks;
 299
 300                 rbp = getblk(vp, loffset, blksize,
 301                              GETBLK_SZMATCH|GETBLK_NOWAIT, 0);
 302                 if (rbp == NULL)
 303                         goto no_read_ahead;
 304                 if ((rbp->b_flags & B_CACHE)) {
 305                         bqrelse(rbp);
 306                         goto no_read_ahead;
 307                 }
 308
 309                 /*
 310                  * An error from the read-ahead bmap has nothing to do
 311                  * with the caller's original request.
 312                  */
 313                 tmp_error = VOP_BMAP(vp, loffset, &doffset,
 314                                      &burstbytes, NULL, BUF_CMD_READ);
 315                 if (tmp_error || doffset == NOOFFSET) {
 316                         rbp->b_flags |= B_INVAL;
 317                         brelse(rbp);
 318                         rbp = NULL;
 319                         goto no_read_ahead;
 320                 }
 321                 if ((nblks = maxra) > maxrbuild)
 322                         nblks = maxrbuild;
 323                 if (nblks > burstbytes / blksize)
 324                         nblks = burstbytes / blksize;
 325
 326                 /*
 327                  * rbp: async read
 328                  */
 329                 rbp->b_cmd = BUF_CMD_READ;
 330                 /*rbp->b_flags |= B_AGE*/;
 331                 cluster_setram(rbp);
 332
 333                 if (nblks > 1) {
 334                         rbp = cluster_rbuild(vp, filesize, loffset,
 335                                              doffset, blksize,
 336                                              nblks, rbp);
 337                 } else {
 338                         rbp->b_bio2.bio_offset = doffset;
 339                 }
 340
 341 #if defined(CLUSTERDEBUG)
 342                 if (rcluster) {
 343                         if (bp) {
 344                                 kprintf("A+(%012jx,%d,%jd) "
 345                                         "doff=%012jx minr=%zd ra=%d\n",
 346                                     (intmax_t)loffset, rbp->b_bcount,
 347                                     (intmax_t)(loffset - origoffset),
 348                                     (intmax_t)doffset, minreq, maxra);
 349                         } else {
 350                                 kprintf("A-(%012jx,%d,%jd) "
 351                                         "doff=%012jx minr=%zd ra=%d\n",
 352                                     (intmax_t)rbp->b_loffset, rbp->b_bcount,
 353                                     (intmax_t)(loffset - origoffset),
 354                                     (intmax_t)doffset, minreq, maxra);
 355                         }
 356                 }
 357 #endif
 358                 rbp->b_flags &= ~(B_ERROR|B_INVAL);
 359
 360                 if ((rbp->b_flags & B_CLUSTER) == 0)
 361                         vfs_busy_pages(vp, rbp);
 362                 BUF_KERNPROC(rbp);
 363                 loffset += rbp->b_bufsize;
 364                 maxra -= rbp->b_bufsize / blksize;
 365                 vn_strategy(vp, &rbp->b_bio1);
 366                 /* rbp invalid now */
 367         }
 368
 369         /*
 370          * Wait for our original buffer to complete its I/O.  reqbp will
 371          * be NULL if the original buffer was B_CACHE.  We are returning
 372          * (*bpp) which is the same as reqbp when reqbp != NULL.
 373          */
 374 no_read_ahead:
 375         if (reqbp) {
 376                 KKASSERT(reqbp->b_bio1.bio_flags & BIO_SYNC);
 377                 error = biowait(&reqbp->b_bio1, "clurd");
 378         }
 379         return (error);
 380 }
 381
 382 /*
 383  * If blocks are contiguous on disk, use this to provide clustered
 384  * read ahead.  We will read as many blocks as possible sequentially
 385  * and then parcel them up into logical blocks in the buffer hash table.
 386  *
 387  * This function either returns a cluster buf or it returns fbp.  fbp is
 388  * already expected to be set up as a synchronous or asynchronous request.
 389  *
 390  * If a cluster buf is returned it will always be async.
 391  */
 392 static struct buf *
 393 cluster_rbuild(struct vnode *vp, off_t filesize, off_t loffset, off_t doffset,
 394                int blksize, int run, struct buf *fbp)
 395 {
 396         struct buf *bp, *tbp;
 397         off_t boffset;
 398         int i, j;
 399         int maxiosize = vmaxiosize(vp);
 400
 401         /*
 402          * avoid a division
 403          */
 404         while (loffset + run * blksize > filesize) {
 405                 --run;
 406         }
 407
 408         tbp = fbp;
 409         tbp->b_bio2.bio_offset = doffset;
 410         if((tbp->b_flags & B_MALLOC) ||
 411             ((tbp->b_flags & B_VMIO) == 0) || (run <= 1)) {
 412                 return tbp;
 413         }
 414
 415         bp = trypbuf_kva(&cluster_pbuf_freecnt);
 416         if (bp == NULL) {
 417                 return tbp;
 418         }
 419
 420         /*
 421          * We are synthesizing a buffer out of vm_page_t's, but
 422          * if the block size is not page aligned then the starting
 423          * address may not be either.  Inherit the b_data offset
 424          * from the original buffer.
 425          */
 426         bp->b_data = (char *)((vm_offset_t)bp->b_data |
 427             ((vm_offset_t)tbp->b_data & PAGE_MASK));
 428         bp->b_flags |= B_CLUSTER | B_VMIO;
 429         bp->b_cmd = BUF_CMD_READ;
 430         bp->b_bio1.bio_done = cluster_callback;         /* default to async */
 431         bp->b_bio1.bio_caller_info1.cluster_head = NULL;
 432         bp->b_bio1.bio_caller_info2.cluster_tail = NULL;
 433         bp->b_loffset = loffset;
 434         bp->b_bio2.bio_offset = doffset;
 435         KASSERT(bp->b_loffset != NOOFFSET,
 436                 ("cluster_rbuild: no buffer offset"));
 437
 438         bp->b_bcount = 0;
 439         bp->b_bufsize = 0;
 440         bp->b_xio.xio_npages = 0;
 441
 442         for (boffset = doffset, i = 0; i < run; ++i, boffset += blksize) {
 443                 if (i) {
 444                         if ((bp->b_xio.xio_npages * PAGE_SIZE) +
 445                             round_page(blksize) > maxiosize) {
 446                                 break;
 447                         }
 448
 449                         /*
 450                          * Shortcut some checks and try to avoid buffers that
 451                          * would block in the lock.  The same checks have to
 452                          * be made again after we officially get the buffer.
 453                          */
 454                         tbp = getblk(vp, loffset + i * blksize, blksize,
 455                                      GETBLK_SZMATCH|GETBLK_NOWAIT, 0);
 456                         if (tbp == NULL)
 457                                 break;
 458                         for (j = 0; j < tbp->b_xio.xio_npages; j++) {
 459                                 if (tbp->b_xio.xio_pages[j]->valid)
 460                                         break;
 461                         }
 462                         if (j != tbp->b_xio.xio_npages) {
 463                                 bqrelse(tbp);
 464                                 break;
 465                         }
 466
 467                         /*
 468                          * Stop scanning if the buffer is fuly valid
 469                          * (marked B_CACHE), or locked (may be doing a
 470                          * background write), or if the buffer is not
 471                          * VMIO backed.  The clustering code can only deal
 472                          * with VMIO-backed buffers.
 473                          */
 474                         if ((tbp->b_flags & (B_CACHE|B_LOCKED)) ||
 475                             (tbp->b_flags & B_VMIO) == 0 ||
 476                             (LIST_FIRST(&tbp->b_dep) != NULL &&
 477                              buf_checkread(tbp))
 478                         ) {
 479                                 bqrelse(tbp);
 480                                 break;
 481                         }
 482
 483                         /*
 484                          * The buffer must be completely invalid in order to
 485                          * take part in the cluster.  If it is partially valid
 486                          * then we stop.
 487                          */
 488                         for (j = 0;j < tbp->b_xio.xio_npages; j++) {
 489                                 if (tbp->b_xio.xio_pages[j]->valid)
 490                                         break;
 491                         }
 492                         if (j != tbp->b_xio.xio_npages) {
 493                                 bqrelse(tbp);
 494                                 break;
 495                         }
 496
 497                         /*
 498                          * Set a read-ahead mark as appropriate
 499                          */
 500                         if (i == 1 || i == (run - 1))
 501                                 cluster_setram(tbp);
 502
 503                         /*
 504                          * Depress the priority of buffers not explicitly
 505                          * requested.
 506                          */
 507                         /* tbp->b_flags |= B_AGE; */
 508
 509                         /*
 510                          * Set the block number if it isn't set, otherwise
 511                          * if it is make sure it matches the block number we
 512                          * expect.
 513                          */
 514                         if (tbp->b_bio2.bio_offset == NOOFFSET) {
 515                                 tbp->b_bio2.bio_offset = boffset;
 516                         } else if (tbp->b_bio2.bio_offset != boffset) {
 517                                 brelse(tbp);
 518                                 break;
 519                         }
 520                 }
 521
 522                 /*
 523                  * The passed-in tbp (i == 0) will already be set up for
 524                  * async or sync operation.  All other tbp's acquire in
 525                  * our loop are set up for async operation.
 526                  */
 527                 tbp->b_cmd = BUF_CMD_READ;
 528                 BUF_KERNPROC(tbp);
 529                 cluster_append(&bp->b_bio1, tbp);
 530                 for (j = 0; j < tbp->b_xio.xio_npages; ++j) {
 531                         vm_page_t m;
 532                         m = tbp->b_xio.xio_pages[j];
 533                         vm_page_io_start(m);
 534                         vm_object_pip_add(m->object, 1);
 535                         if ((bp->b_xio.xio_npages == 0) ||
 536                                 (bp->b_xio.xio_pages[bp->b_xio.xio_npages-1] != m)) {
 537                                 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m;
 538                                 bp->b_xio.xio_npages++;
 539                         }
 540                         if ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL)
 541                                 tbp->b_xio.xio_pages[j] = bogus_page;
 542                 }
 543                 /*
 544                  * XXX shouldn't this be += size for both, like in
 545                  * cluster_wbuild()?
 546                  *
 547                  * Don't inherit tbp->b_bufsize as it may be larger due to
 548                  * a non-page-aligned size.  Instead just aggregate using
 549                  * 'size'.
 550                  */
 551                 if (tbp->b_bcount != blksize)
 552                     kprintf("warning: tbp->b_bcount wrong %d vs %d\n", tbp->b_bcount, blksize);
 553                 if (tbp->b_bufsize != blksize)
 554                     kprintf("warning: tbp->b_bufsize wrong %d vs %d\n", tbp->b_bufsize, blksize);
 555                 bp->b_bcount += blksize;
 556                 bp->b_bufsize += blksize;
 557         }
 558
 559         /*
 560          * Fully valid pages in the cluster are already good and do not need
 561          * to be re-read from disk.  Replace the page with bogus_page
 562          */
 563         for (j = 0; j < bp->b_xio.xio_npages; j++) {
 564                 if ((bp->b_xio.xio_pages[j]->valid & VM_PAGE_BITS_ALL) ==
 565                     VM_PAGE_BITS_ALL) {
 566                         bp->b_xio.xio_pages[j] = bogus_page;
 567                 }
 568         }
 569         if (bp->b_bufsize > bp->b_kvasize) {
 570                 panic("cluster_rbuild: b_bufsize(%d) > b_kvasize(%d)",
 571                     bp->b_bufsize, bp->b_kvasize);
 572         }
 573         pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
 574                 (vm_page_t *)bp->b_xio.xio_pages, bp->b_xio.xio_npages);
 575         BUF_KERNPROC(bp);
 576         return (bp);
 577 }
 578
 579 /*
 580  * Cleanup after a clustered read or write.
 581  * This is complicated by the fact that any of the buffers might have
 582  * extra memory (if there were no empty buffer headers at allocbuf time)
 583  * that we will need to shift around.
 584  *
 585  * The returned bio is &bp->b_bio1
 586  */
 587 void
 588 cluster_callback(struct bio *bio)
 589 {
 590         struct buf *bp = bio->bio_buf;
 591         struct buf *tbp;
 592         int error = 0;
 593
 594         /*
 595          * Must propogate errors to all the components.  A short read (EOF)
 596          * is a critical error.
 597          */
 598         if (bp->b_flags & B_ERROR) {
 599                 error = bp->b_error;
 600         } else if (bp->b_bcount != bp->b_bufsize) {
 601                 panic("cluster_callback: unexpected EOF on cluster %p!", bio);
 602         }
 603
 604         pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_xio.xio_npages);
 605         /*
 606          * Move memory from the large cluster buffer into the component
 607          * buffers and mark IO as done on these.  Since the memory map
 608          * is the same, no actual copying is required.
 609          */
 610         while ((tbp = bio->bio_caller_info1.cluster_head) != NULL) {
 611                 bio->bio_caller_info1.cluster_head = tbp->b_cluster_next;
 612                 if (error) {
 613                         tbp->b_flags |= B_ERROR | B_IODEBUG;
 614                         tbp->b_error = error;
 615                 } else {
 616                         tbp->b_dirtyoff = tbp->b_dirtyend = 0;
 617                         tbp->b_flags &= ~(B_ERROR|B_INVAL);
 618                         tbp->b_flags |= B_IODEBUG;
 619                         /*
 620                          * XXX the bdwrite()/bqrelse() issued during
 621                          * cluster building clears B_RELBUF (see bqrelse()
 622                          * comment).  If direct I/O was specified, we have
 623                          * to restore it here to allow the buffer and VM
 624                          * to be freed.
 625                          */
 626                         if (tbp->b_flags & B_DIRECT)
 627                                 tbp->b_flags |= B_RELBUF;
 628                 }
 629                 biodone(&tbp->b_bio1);
 630         }
 631         relpbuf(bp, &cluster_pbuf_freecnt);
 632 }
 633
 634 /*
 635  *      cluster_wbuild_wb:
 636  *
 637  *      Implement modified write build for cluster.
 638  *
 639  *              write_behind = 0        write behind disabled
 640  *              write_behind = 1        write behind normal (default)
 641  *              write_behind = 2        write behind backed-off
 642  */
 643
 644 static __inline int
 645 cluster_wbuild_wb(struct vnode *vp, int blksize, off_t start_loffset, int len)
 646 {
 647         int r = 0;
 648
 649         switch(write_behind) {
 650         case 2:
 651                 if (start_loffset < len)
 652                         break;
 653                 start_loffset -= len;
 654                 /* fall through */
 655         case 1:
 656                 r = cluster_wbuild(vp, blksize, start_loffset, len);
 657                 /* fall through */
 658         default:
 659                 /* fall through */
 660                 break;
 661         }
 662         return(r);
 663 }
 664
 665 /*
 666  * Do clustered write for FFS.
 667  *
 668  * Three cases:
 669  *      1. Write is not sequential (write asynchronously)
 670  *      Write is sequential:
 671  *      2.      beginning of cluster - begin cluster
 672  *      3.      middle of a cluster - add to cluster
 673  *      4.      end of a cluster - asynchronously write cluster
 674  */
 675 void
 676 cluster_write(struct buf *bp, off_t filesize, int blksize, int seqcount)
 677 {
 678         struct vnode *vp;
 679         off_t loffset;
 680         int maxclen, cursize;
 681         int async;
 682
 683         vp = bp->b_vp;
 684         if (vp->v_type == VREG)
 685                 async = vp->v_mount->mnt_flag & MNT_ASYNC;
 686         else
 687                 async = 0;
 688         loffset = bp->b_loffset;
 689         KASSERT(bp->b_loffset != NOOFFSET,
 690                 ("cluster_write: no buffer offset"));
 691
 692         /* Initialize vnode to beginning of file. */
 693         if (loffset == 0)
 694                 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0;
 695
 696         if (vp->v_clen == 0 || loffset != vp->v_lastw + blksize ||
 697             bp->b_bio2.bio_offset == NOOFFSET ||
 698             (bp->b_bio2.bio_offset != vp->v_lasta + blksize)) {
 699                 maxclen = vmaxiosize(vp);
 700                 if (vp->v_clen != 0) {
 701                         /*
 702                          * Next block is not sequential.
 703                          *
 704                          * If we are not writing at end of file, the process
 705                          * seeked to another point in the file since its last
 706                          * write, or we have reached our maximum cluster size,
 707                          * then push the previous cluster. Otherwise try
 708                          * reallocating to make it sequential.
 709                          *
 710                          * Change to algorithm: only push previous cluster if
 711                          * it was sequential from the point of view of the
 712                          * seqcount heuristic, otherwise leave the buffer
 713                          * intact so we can potentially optimize the I/O
 714                          * later on in the buf_daemon or update daemon
 715                          * flush.
 716                          */
 717                         cursize = vp->v_lastw - vp->v_cstart + blksize;
 718                         if (bp->b_loffset + blksize != filesize ||
 719                             loffset != vp->v_lastw + blksize || vp->v_clen <= cursize) {
 720                                 if (!async && seqcount > 0) {
 721                                         cluster_wbuild_wb(vp, blksize,
 722                                                 vp->v_cstart, cursize);
 723                                 }
 724                         } else {
 725                                 struct buf **bpp, **endbp;
 726                                 struct cluster_save *buflist;
 727
 728                                 buflist = cluster_collectbufs(vp, bp, blksize);
 729                                 endbp = &buflist->bs_children
 730                                     [buflist->bs_nchildren - 1];
 731                                 if (VOP_REALLOCBLKS(vp, buflist)) {
 732                                         /*
 733                                          * Failed, push the previous cluster
 734                                          * if *really* writing sequentially
 735                                          * in the logical file (seqcount > 1),
 736                                          * otherwise delay it in the hopes that
 737                                          * the low level disk driver can
 738                                          * optimize the write ordering.
 739                                          */
 740                                         for (bpp = buflist->bs_children;
 741                                              bpp < endbp; bpp++)
 742                                                 brelse(*bpp);
 743                                         kfree(buflist, M_SEGMENT);
 744                                         if (seqcount > 1) {
 745                                                 cluster_wbuild_wb(vp,
 746                                                     blksize, vp->v_cstart,
 747                                                     cursize);
 748                                         }
 749                                 } else {
 750                                         /*
 751                                          * Succeeded, keep building cluster.
 752                                          */
 753                                         for (bpp = buflist->bs_children;
 754                                              bpp <= endbp; bpp++)
 755                                                 bdwrite(*bpp);
 756                                         kfree(buflist, M_SEGMENT);
 757                                         vp->v_lastw = loffset;
 758                                         vp->v_lasta = bp->b_bio2.bio_offset;
 759                                         return;
 760                                 }
 761                         }
 762                 }
 763                 /*
 764                  * Consider beginning a cluster. If at end of file, make
 765                  * cluster as large as possible, otherwise find size of
 766                  * existing cluster.
 767                  */
 768                 if ((vp->v_type == VREG) &&
 769                     bp->b_loffset + blksize != filesize &&
 770                     (bp->b_bio2.bio_offset == NOOFFSET) &&
 771                     (VOP_BMAP(vp, loffset, &bp->b_bio2.bio_offset, &maxclen, NULL, BUF_CMD_WRITE) ||
 772                      bp->b_bio2.bio_offset == NOOFFSET)) {
 773                         bawrite(bp);
 774                         vp->v_clen = 0;
 775                         vp->v_lasta = bp->b_bio2.bio_offset;
 776                         vp->v_cstart = loffset + blksize;
 777                         vp->v_lastw = loffset;
 778                         return;
 779                 }
 780                 if (maxclen > blksize)
 781                         vp->v_clen = maxclen - blksize;
 782                 else
 783                         vp->v_clen = 0;
 784                 if (!async && vp->v_clen == 0) { /* I/O not contiguous */
 785                         vp->v_cstart = loffset + blksize;
 786                         bawrite(bp);
 787                 } else {        /* Wait for rest of cluster */
 788                         vp->v_cstart = loffset;
 789                         bdwrite(bp);
 790                 }
 791         } else if (loffset == vp->v_cstart + vp->v_clen) {
 792                 /*
 793                  * At end of cluster, write it out if seqcount tells us we
 794                  * are operating sequentially, otherwise let the buf or
 795                  * update daemon handle it.
 796                  */
 797                 bdwrite(bp);
 798                 if (seqcount > 1)
 799                         cluster_wbuild_wb(vp, blksize, vp->v_cstart,
 800                                           vp->v_clen + blksize);
 801                 vp->v_clen = 0;
 802                 vp->v_cstart = loffset + blksize;
 803         } else if (vm_page_count_severe()) {
 804                 /*
 805                  * We are low on memory, get it going NOW
 806                  */
 807                 bawrite(bp);
 808         } else {
 809                 /*
 810                  * In the middle of a cluster, so just delay the I/O for now.
 811                  */
 812                 bdwrite(bp);
 813         }
 814         vp->v_lastw = loffset;
 815         vp->v_lasta = bp->b_bio2.bio_offset;
 816 }
 817
 818
 819 /*
 820  * This is an awful lot like cluster_rbuild...wish they could be combined.
 821  * The last lbn argument is the current block on which I/O is being
 822  * performed.  Check to see that it doesn't fall in the middle of
 823  * the current block (if last_bp == NULL).
 824  */
 825 int
 826 cluster_wbuild(struct vnode *vp, int blksize, off_t start_loffset, int bytes)
 827 {
 828         struct buf *bp, *tbp;
 829         int i, j;
 830         int totalwritten = 0;
 831         int maxiosize = vmaxiosize(vp);
 832
 833         while (bytes > 0) {
 834                 /*
 835                  * If the buffer is not delayed-write (i.e. dirty), or it
 836                  * is delayed-write but either locked or inval, it cannot
 837                  * partake in the clustered write.
 838                  */
 839                 tbp = findblk(vp, start_loffset, FINDBLK_NBLOCK);
 840                 if (tbp == NULL ||
 841                     (tbp->b_flags & (B_LOCKED | B_INVAL | B_DELWRI)) != B_DELWRI ||
 842                     (LIST_FIRST(&tbp->b_dep) && buf_checkwrite(tbp))) {
 843                         if (tbp)
 844                                 BUF_UNLOCK(tbp);
 845                         start_loffset += blksize;
 846                         bytes -= blksize;
 847                         continue;
 848                 }
 849                 bremfree(tbp);
 850                 KKASSERT(tbp->b_cmd == BUF_CMD_DONE);
 851
 852                 /*
 853                  * Extra memory in the buffer, punt on this buffer.
 854                  * XXX we could handle this in most cases, but we would
 855                  * have to push the extra memory down to after our max
 856                  * possible cluster size and then potentially pull it back
 857                  * up if the cluster was terminated prematurely--too much
 858                  * hassle.
 859                  */
 860                 if (((tbp->b_flags & (B_CLUSTEROK|B_MALLOC)) != B_CLUSTEROK) ||
 861                     (tbp->b_bcount != tbp->b_bufsize) ||
 862                     (tbp->b_bcount != blksize) ||
 863                     (bytes == blksize) ||
 864                     ((bp = getpbuf_kva(&cluster_pbuf_freecnt)) == NULL)) {
 865                         totalwritten += tbp->b_bufsize;
 866                         bawrite(tbp);
 867                         start_loffset += blksize;
 868                         bytes -= blksize;
 869                         continue;
 870                 }
 871
 872                 /*
 873                  * Set up the pbuf.  Track our append point with b_bcount
 874                  * and b_bufsize.  b_bufsize is not used by the device but
 875                  * our caller uses it to loop clusters and we use it to
 876                  * detect a premature EOF on the block device.
 877                  */
 878                 bp->b_bcount = 0;
 879                 bp->b_bufsize = 0;
 880                 bp->b_xio.xio_npages = 0;
 881                 bp->b_loffset = tbp->b_loffset;
 882                 bp->b_bio2.bio_offset = tbp->b_bio2.bio_offset;
 883
 884                 /*
 885                  * We are synthesizing a buffer out of vm_page_t's, but
 886                  * if the block size is not page aligned then the starting
 887                  * address may not be either.  Inherit the b_data offset
 888                  * from the original buffer.
 889                  */
 890                 bp->b_data = (char *)((vm_offset_t)bp->b_data |
 891                     ((vm_offset_t)tbp->b_data & PAGE_MASK));
 892                 bp->b_flags &= ~B_ERROR;
 893                 bp->b_flags |= B_CLUSTER | B_BNOCLIP |
 894                         (tbp->b_flags & (B_VMIO | B_NEEDCOMMIT));
 895                 bp->b_bio1.bio_caller_info1.cluster_head = NULL;
 896                 bp->b_bio1.bio_caller_info2.cluster_tail = NULL;
 897
 898                 /*
 899                  * From this location in the file, scan forward to see
 900                  * if there are buffers with adjacent data that need to
 901                  * be written as well.
 902                  */
 903                 for (i = 0; i < bytes; (i += blksize), (start_loffset += blksize)) {
 904                         if (i != 0) { /* If not the first buffer */
 905                                 tbp = findblk(vp, start_loffset,
 906                                               FINDBLK_NBLOCK);
 907                                 /*
 908                                  * Buffer not found or could not be locked
 909                                  * non-blocking.
 910                                  */
 911                                 if (tbp == NULL)
 912                                         break;
 913
 914                                 /*
 915                                  * If it IS in core, but has different
 916                                  * characteristics, then don't cluster
 917                                  * with it.
 918                                  */
 919                                 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK |
 920                                      B_INVAL | B_DELWRI | B_NEEDCOMMIT))
 921                                     != (B_DELWRI | B_CLUSTEROK |
 922                                      (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) ||
 923                                     (tbp->b_flags & B_LOCKED) ||
 924                                     (LIST_FIRST(&tbp->b_dep) &&
 925                                      buf_checkwrite(tbp))
 926                                 ) {
 927                                         BUF_UNLOCK(tbp);
 928                                         break;
 929                                 }
 930
 931                                 /*
 932                                  * Check that the combined cluster
 933                                  * would make sense with regard to pages
 934                                  * and would not be too large
 935                                  */
 936                                 if ((tbp->b_bcount != blksize) ||
 937                                   ((bp->b_bio2.bio_offset + i) !=
 938                                     tbp->b_bio2.bio_offset) ||
 939                                   ((tbp->b_xio.xio_npages + bp->b_xio.xio_npages) >
 940                                     (maxiosize / PAGE_SIZE))) {
 941                                         BUF_UNLOCK(tbp);
 942                                         break;
 943                                 }
 944                                 /*
 945                                  * Ok, it's passed all the tests,
 946                                  * so remove it from the free list
 947                                  * and mark it busy. We will use it.
 948                                  */
 949                                 bremfree(tbp);
 950                                 KKASSERT(tbp->b_cmd == BUF_CMD_DONE);
 951                         } /* end of code for non-first buffers only */
 952
 953                         /*
 954                          * If the IO is via the VM then we do some
 955                          * special VM hackery (yuck).  Since the buffer's
 956                          * block size may not be page-aligned it is possible
 957                          * for a page to be shared between two buffers.  We
 958                          * have to get rid of the duplication when building
 959                          * the cluster.
 960                          */
 961                         if (tbp->b_flags & B_VMIO) {
 962                                 vm_page_t m;
 963
 964                                 if (i != 0) { /* if not first buffer */
 965                                         for (j = 0; j < tbp->b_xio.xio_npages; ++j) {
 966                                                 m = tbp->b_xio.xio_pages[j];
 967                                                 if (m->flags & PG_BUSY) {
 968                                                         bqrelse(tbp);
 969                                                         goto finishcluster;
 970                                                 }
 971                                         }
 972                                 }
 973
 974                                 for (j = 0; j < tbp->b_xio.xio_npages; ++j) {
 975                                         m = tbp->b_xio.xio_pages[j];
 976                                         vm_page_io_start(m);
 977                                         vm_object_pip_add(m->object, 1);
 978                                         if ((bp->b_xio.xio_npages == 0) ||
 979                                           (bp->b_xio.xio_pages[bp->b_xio.xio_npages - 1] != m)) {
 980                                                 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m;
 981                                                 bp->b_xio.xio_npages++;
 982                                         }
 983                                 }
 984                         }
 985                         bp->b_bcount += blksize;
 986                         bp->b_bufsize += blksize;
 987
 988                         bundirty(tbp);
 989                         tbp->b_flags &= ~B_ERROR;
 990                         tbp->b_cmd = BUF_CMD_WRITE;
 991                         BUF_KERNPROC(tbp);
 992                         cluster_append(&bp->b_bio1, tbp);
 993
 994                         /*
 995                          * check for latent dependencies to be handled
 996                          */
 997                         if (LIST_FIRST(&tbp->b_dep) != NULL)
 998                                 buf_start(tbp);
 999                 }
1000         finishcluster:
1001                 pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
1002                         (vm_page_t *) bp->b_xio.xio_pages, bp->b_xio.xio_npages);
1003                 if (bp->b_bufsize > bp->b_kvasize) {
1004                         panic(
1005                             "cluster_wbuild: b_bufsize(%d) > b_kvasize(%d)\n",
1006                             bp->b_bufsize, bp->b_kvasize);
1007                 }
1008                 totalwritten += bp->b_bufsize;
1009                 bp->b_dirtyoff = 0;
1010                 bp->b_dirtyend = bp->b_bufsize;
1011                 bp->b_bio1.bio_done = cluster_callback;
1012                 bp->b_cmd = BUF_CMD_WRITE;
1013
1014                 vfs_busy_pages(vp, bp);
1015                 bp->b_runningbufspace = bp->b_bufsize;
1016                 if (bp->b_runningbufspace) {
1017                         runningbufspace += bp->b_runningbufspace;
1018                         ++runningbufcount;
1019                 }
1020                 BUF_KERNPROC(bp);
1021                 vn_strategy(vp, &bp->b_bio1);
1022
1023                 bytes -= i;
1024         }
1025         return totalwritten;
1026 }
1027
1028 /*
1029  * Collect together all the buffers in a cluster.
1030  * Plus add one additional buffer.
1031  */
1032 static struct cluster_save *
1033 cluster_collectbufs(struct vnode *vp, struct buf *last_bp, int blksize)
1034 {
1035         struct cluster_save *buflist;
1036         struct buf *bp;
1037         off_t loffset;
1038         int i, len;
1039
1040         len = (int)(vp->v_lastw - vp->v_cstart + blksize) / blksize;
1041         buflist = kmalloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist),
1042                          M_SEGMENT, M_WAITOK);
1043         buflist->bs_nchildren = 0;
1044         buflist->bs_children = (struct buf **) (buflist + 1);
1045         for (loffset = vp->v_cstart, i = 0; i < len; (loffset += blksize), i++) {
1046                 (void) bread(vp, loffset, last_bp->b_bcount, &bp);
1047                 buflist->bs_children[i] = bp;
1048                 if (bp->b_bio2.bio_offset == NOOFFSET) {
1049                         VOP_BMAP(bp->b_vp, bp->b_loffset,
1050                                  &bp->b_bio2.bio_offset,
1051                                  NULL, NULL, BUF_CMD_WRITE);
1052                 }
1053         }
1054         buflist->bs_children[i] = bp = last_bp;
1055         if (bp->b_bio2.bio_offset == NOOFFSET) {
1056                 VOP_BMAP(bp->b_vp, bp->b_loffset, &bp->b_bio2.bio_offset,
1057                          NULL, NULL, BUF_CMD_WRITE);
1058         }
1059         buflist->bs_nchildren = i + 1;
1060         return (buflist);
1061 }
1062
1063 void
1064 cluster_append(struct bio *bio, struct buf *tbp)
1065 {
1066         tbp->b_cluster_next = NULL;
1067         if (bio->bio_caller_info1.cluster_head == NULL) {
1068                 bio->bio_caller_info1.cluster_head = tbp;
1069                 bio->bio_caller_info2.cluster_tail = tbp;
1070         } else {
1071                 bio->bio_caller_info2.cluster_tail->b_cluster_next = tbp;
1072                 bio->bio_caller_info2.cluster_tail = tbp;
1073         }
1074 }
1075
1076 static
1077 void
1078 cluster_setram (struct buf *bp)
1079 {
1080         bp->b_flags |= B_RAM;
1081         if (bp->b_xio.xio_npages)
1082                 vm_page_flag_set(bp->b_xio.xio_pages[0], PG_RAM);
1083 }