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
  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 }