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. Neither the name of the University nor the names of its contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  *
  31  *      @(#)vfs_cluster.c       8.7 (Berkeley) 2/13/94
  32  * $FreeBSD: src/sys/kern/vfs_cluster.c,v 1.92.2.9 2001/11/18 07:10:59 dillon Exp $
  33  * $DragonFly: src/sys/kern/vfs_cluster.c,v 1.40 2008/07/14 03:09:00 dillon Exp $
  34  */
  35
  36 #include "opt_debug_cluster.h"
  37
  38 #include <sys/param.h>
  39 #include <sys/systm.h>
  40 #include <sys/kernel.h>
  41 #include <sys/proc.h>
  42 #include <sys/buf.h>
  43 #include <sys/vnode.h>
  44 #include <sys/malloc.h>
  45 #include <sys/mount.h>
  46 #include <sys/resourcevar.h>
  47 #include <sys/vmmeter.h>
  48 #include <vm/vm.h>
  49 #include <vm/vm_object.h>
  50 #include <vm/vm_page.h>
  51 #include <sys/sysctl.h>
  52
  53 #include <sys/buf2.h>
  54 #include <vm/vm_page2.h>
  55
  56 #include <machine/limits.h>
  57
  58 #if defined(CLUSTERDEBUG)
  59 #include <sys/sysctl.h>
  60 static int      rcluster= 0;
  61 SYSCTL_INT(_debug, OID_AUTO, rcluster, CTLFLAG_RW, &rcluster, 0, "");
  62 #endif
  63
  64 static MALLOC_DEFINE(M_SEGMENT, "cluster_save", "cluster_save buffer");
  65
  66 static struct cluster_save *
  67         cluster_collectbufs (struct vnode *vp, struct buf *last_bp,
  68                             int blksize);
  69 static struct buf *
  70         cluster_rbuild (struct vnode *vp, off_t filesize, off_t loffset,
  71                             off_t doffset, int blksize, int run,
  72                             struct buf *fbp);
  73 static void cluster_callback (struct bio *);
  74 static void cluster_setram (struct buf *);
  75 static int cluster_wbuild(struct vnode *vp, struct buf **bpp, int blksize,
  76                             off_t start_loffset, int bytes);
  77
  78 static int write_behind = 1;
  79 SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0,
  80     "Cluster write-behind setting");
  81 static quad_t write_behind_minfilesize = 10 * 1024 * 1024;
  82 SYSCTL_QUAD(_vfs, OID_AUTO, write_behind_minfilesize, CTLFLAG_RW,
  83     &write_behind_minfilesize, 0, "Cluster write-behind setting");
  84 static int max_readahead = 2 * 1024 * 1024;
  85 SYSCTL_INT(_vfs, OID_AUTO, max_readahead, CTLFLAG_RW, &max_readahead, 0,
  86     "Limit in bytes for desired cluster read-ahead");
  87
  88 extern vm_page_t        bogus_page;
  89
  90 extern int cluster_pbuf_freecnt;
  91
  92 /*
  93  * This replaces bread(), providing a synchronous read of the requested
  94  * buffer plus asynchronous read-ahead within the specified bounds.
  95  *
  96  * The caller may pre-populate *bpp if it already has the requested buffer
  97  * in-hand, else must set *bpp to NULL.  Note that the cluster_read() inline
  98  * sets *bpp to NULL and then calls cluster_readx() for compatibility.
  99  *
 100  * filesize     - read-ahead @ blksize will not cross this boundary
 101  * loffset      - loffset for returned *bpp
 102  * blksize      - blocksize for returned *bpp and read-ahead bps
 103  * minreq       - minimum (not a hard minimum) in bytes, typically reflects
 104  *                a higher level uio resid.
 105  * maxreq       - maximum (sequential heuristic) in bytes (highet typ ~2MB)
 106  * bpp          - return buffer (*bpp) for (loffset,blksize)
 107  */
 108 int
 109 cluster_readx(struct vnode *vp, off_t filesize, off_t loffset,
 110              int blksize, size_t minreq, size_t maxreq, struct buf **bpp)
 111 {
 112         struct buf *bp, *rbp, *reqbp;
 113         off_t origoffset;
 114         off_t doffset;
 115         int error;
 116         int i;
 117         int maxra;
 118         int maxrbuild;
 119
 120         error = 0;
 121
 122         /*
 123          * Calculate the desired read-ahead in blksize'd blocks (maxra).
 124          * To do this we calculate maxreq.
 125          *
 126          * maxreq typically starts out as a sequential heuristic.  If the
 127          * high level uio/resid is bigger (minreq), we pop maxreq up to
 128          * minreq.  This represents the case where random I/O is being
 129          * performed by the userland is issuing big read()'s.
 130          *
 131          * Then we limit maxreq to max_readahead to ensure it is a reasonable
 132          * value.
 133          *
 134          * Finally we must ensure that (loffset + maxreq) does not cross the
 135          * boundary (filesize) for the current blocksize.  If we allowed it
 136          * to cross we could end up with buffers past the boundary with the
 137          * wrong block size (HAMMER large-data areas use mixed block sizes).
 138          * minreq is also absolutely limited to filesize.
 139          */
 140         if (maxreq < minreq)
 141                 maxreq = minreq;
 142         /* minreq not used beyond this point */
 143
 144         if (maxreq > max_readahead) {
 145                 maxreq = max_readahead;
 146                 if (maxreq > 16 * 1024 * 1024)
 147                         maxreq = 16 * 1024 * 1024;
 148         }
 149         if (maxreq < blksize)
 150                 maxreq = blksize;
 151         if (loffset + maxreq > filesize) {
 152                 if (loffset > filesize)
 153                         maxreq = 0;
 154                 else
 155                         maxreq = filesize - loffset;
 156         }
 157
 158         maxra = (int)(maxreq / blksize);
 159
 160         /*
 161          * Get the requested block.
 162          */
 163         if (*bpp)
 164                 reqbp = bp = *bpp;
 165         else
 166                 *bpp = reqbp = bp = getblk(vp, loffset, blksize, 0, 0);
 167         origoffset = loffset;
 168
 169         /*
 170          * Calculate the maximum cluster size for a single I/O, used
 171          * by cluster_rbuild().
 172          */
 173         maxrbuild = vmaxiosize(vp) / blksize;
 174
 175         /*
 176          * if it is in the cache, then check to see if the reads have been
 177          * sequential.  If they have, then try some read-ahead, otherwise
 178          * back-off on prospective read-aheads.
 179          */
 180         if (bp->b_flags & B_CACHE) {
 181                 /*
 182                  * Not sequential, do not do any read-ahead
 183                  */
 184                 if (maxra <= 1)
 185                         return 0;
 186
 187                 /*
 188                  * No read-ahead mark, do not do any read-ahead
 189                  * yet.
 190                  */
 191                 if ((bp->b_flags & B_RAM) == 0)
 192                         return 0;
 193
 194                 /*
 195                  * We hit a read-ahead-mark, figure out how much read-ahead
 196                  * to do (maxra) and where to start (loffset).
 197                  *
 198                  * Shortcut the scan.  Typically the way this works is that
 199                  * we've built up all the blocks inbetween except for the
 200                  * last in previous iterations, so if the second-to-last
 201                  * block is present we just skip ahead to it.
 202                  *
 203                  * This algorithm has O(1) cpu in the steady state no
 204                  * matter how large maxra is.
 205                  */
 206                 bp->b_flags &= ~B_RAM;
 207
 208                 if (findblk(vp, loffset + (maxra - 2) * blksize, FINDBLK_TEST))
 209                         i = maxra - 1;
 210                 else
 211                         i = 1;
 212                 while (i < maxra) {
 213                         if (findblk(vp, loffset + i * blksize,
 214                                     FINDBLK_TEST) == NULL) {
 215                                 break;
 216                         }
 217                         ++i;
 218                 }
 219
 220                 /*
 221                  * We got everything or everything is in the cache, no
 222                  * point continuing.
 223                  */
 224                 if (i >= maxra)
 225                         return 0;
 226
 227                 /*
 228                  * Calculate where to start the read-ahead and how much
 229                  * to do.  Generally speaking we want to read-ahead by
 230                  * (maxra) when we've found a read-ahead mark.  We do
 231                  * not want to reduce maxra here as it will cause
 232                  * successive read-ahead I/O's to be smaller and smaller.
 233                  *
 234                  * However, we have to make sure we don't break the
 235                  * filesize limitation for the clustered operation.
 236                  */
 237                 loffset += i * blksize;
 238                 reqbp = bp = NULL;
 239
 240                 if (loffset >= filesize)
 241                         return 0;
 242                 if (loffset + maxra * blksize > filesize) {
 243                         maxreq = filesize - loffset;
 244                         maxra = (int)(maxreq / blksize);
 245                 }
 246         } else {
 247                 __debugvar off_t firstread = bp->b_loffset;
 248                 int nblks;
 249
 250                 /*
 251                  * Set-up synchronous read for bp.
 252                  */
 253                 bp->b_cmd = BUF_CMD_READ;
 254                 bp->b_bio1.bio_done = biodone_sync;
 255                 bp->b_bio1.bio_flags |= BIO_SYNC;
 256
 257                 KASSERT(firstread != NOOFFSET,
 258                         ("cluster_read: no buffer offset"));
 259
 260                 /*
 261                  * nblks is our cluster_rbuild request size, limited
 262                  * primarily by the device.
 263                  */
 264                 if ((nblks = maxra) > maxrbuild)
 265                         nblks = maxrbuild;
 266
 267                 if (nblks > 1) {
 268                         int burstbytes;
 269
 270                         error = VOP_BMAP(vp, loffset, &doffset,
 271                                          &burstbytes, NULL, BUF_CMD_READ);
 272                         if (error)
 273                                 goto single_block_read;
 274                         if (nblks > burstbytes / blksize)
 275                                 nblks = burstbytes / blksize;
 276                         if (doffset == NOOFFSET)
 277                                 goto single_block_read;
 278                         if (nblks <= 1)
 279                                 goto single_block_read;
 280
 281                         bp = cluster_rbuild(vp, filesize, loffset,
 282                                             doffset, blksize, nblks, bp);
 283                         loffset += bp->b_bufsize;
 284                         maxra -= bp->b_bufsize / blksize;
 285                 } else {
 286 single_block_read:
 287                         /*
 288                          * If it isn't in the cache, then get a chunk from
 289                          * disk if sequential, otherwise just get the block.
 290                          */
 291                         cluster_setram(bp);
 292                         loffset += blksize;
 293                         --maxra;
 294                 }
 295         }
 296
 297         /*
 298          * If B_CACHE was not set issue bp.  bp will either be an
 299          * asynchronous cluster buf or a synchronous single-buf.
 300          * If it is a single buf it will be the same as reqbp.
 301          *
 302          * NOTE: Once an async cluster buf is issued bp becomes invalid.
 303          */
 304         if (bp) {
 305 #if defined(CLUSTERDEBUG)
 306                 if (rcluster)
 307                         kprintf("S(%012jx,%d,%d)\n",
 308                             (intmax_t)bp->b_loffset, bp->b_bcount, maxra);
 309 #endif
 310                 if ((bp->b_flags & B_CLUSTER) == 0)
 311                         vfs_busy_pages(vp, bp);
 312                 bp->b_flags &= ~(B_ERROR|B_INVAL);
 313                 vn_strategy(vp, &bp->b_bio1);
 314                 error = 0;
 315                 /* bp invalid now */
 316                 bp = NULL;
 317         }
 318
 319         /*
 320          * If we have been doing sequential I/O, then do some read-ahead.
 321          * The code above us should have positioned us at the next likely
 322          * offset.
 323          *
 324          * Only mess with buffers which we can immediately lock.  HAMMER
 325          * will do device-readahead irrespective of what the blocks
 326          * represent.
 327          */
 328         while (error == 0 && maxra > 0) {
 329                 int burstbytes;
 330                 int tmp_error;
 331                 int nblks;
 332
 333                 rbp = getblk(vp, loffset, blksize,
 334                              GETBLK_SZMATCH|GETBLK_NOWAIT, 0);
 335                 if (rbp == NULL)
 336                         goto no_read_ahead;
 337                 if ((rbp->b_flags & B_CACHE)) {
 338                         bqrelse(rbp);
 339                         goto no_read_ahead;
 340                 }
 341
 342                 /*
 343                  * An error from the read-ahead bmap has nothing to do
 344                  * with the caller's original request.
 345                  */
 346                 tmp_error = VOP_BMAP(vp, loffset, &doffset,
 347                                      &burstbytes, NULL, BUF_CMD_READ);
 348                 if (tmp_error || doffset == NOOFFSET) {
 349                         rbp->b_flags |= B_INVAL;
 350                         brelse(rbp);
 351                         rbp = NULL;
 352                         goto no_read_ahead;
 353                 }
 354                 if ((nblks = maxra) > maxrbuild)
 355                         nblks = maxrbuild;
 356                 if (nblks > burstbytes / blksize)
 357                         nblks = burstbytes / blksize;
 358
 359                 /*
 360                  * rbp: async read
 361                  */
 362                 rbp->b_cmd = BUF_CMD_READ;
 363                 /*rbp->b_flags |= B_AGE*/;
 364                 cluster_setram(rbp);
 365
 366                 if (nblks > 1) {
 367                         rbp = cluster_rbuild(vp, filesize, loffset,
 368                                              doffset, blksize,
 369                                              nblks, rbp);
 370                 } else {
 371                         rbp->b_bio2.bio_offset = doffset;
 372                 }
 373
 374                 rbp->b_flags &= ~(B_ERROR|B_INVAL);
 375
 376                 if ((rbp->b_flags & B_CLUSTER) == 0)
 377                         vfs_busy_pages(vp, rbp);
 378                 BUF_KERNPROC(rbp);
 379                 loffset += rbp->b_bufsize;
 380                 maxra -= rbp->b_bufsize / blksize;
 381                 vn_strategy(vp, &rbp->b_bio1);
 382                 /* rbp invalid now */
 383         }
 384
 385         /*
 386          * Wait for our original buffer to complete its I/O.  reqbp will
 387          * be NULL if the original buffer was B_CACHE.  We are returning
 388          * (*bpp) which is the same as reqbp when reqbp != NULL.
 389          */
 390 no_read_ahead:
 391         if (reqbp) {
 392                 KKASSERT(reqbp->b_bio1.bio_flags & BIO_SYNC);
 393                 error = biowait(&reqbp->b_bio1, "clurd");
 394         }
 395         return (error);
 396 }
 397
 398 /*
 399  * This replaces breadcb(), providing an asynchronous read of the requested
 400  * buffer with a callback, plus an asynchronous read-ahead within the
 401  * specified bounds.
 402  *
 403  * The callback must check whether BIO_DONE is set in the bio and issue
 404  * the bpdone(bp, 0) if it isn't.  The callback is responsible for clearing
 405  * BIO_DONE and disposing of the I/O (bqrelse()ing it).
 406  *
 407  * filesize     - read-ahead @ blksize will not cross this boundary
 408  * loffset      - loffset for returned *bpp
 409  * blksize      - blocksize for returned *bpp and read-ahead bps
 410  * minreq       - minimum (not a hard minimum) in bytes, typically reflects
 411  *                a higher level uio resid.
 412  * maxreq       - maximum (sequential heuristic) in bytes (highet typ ~2MB)
 413  * bpp          - return buffer (*bpp) for (loffset,blksize)
 414  */
 415 void
 416 cluster_readcb(struct vnode *vp, off_t filesize, off_t loffset,
 417              int blksize, size_t minreq, size_t maxreq,
 418              void (*func)(struct bio *), void *arg)
 419 {
 420         struct buf *bp, *rbp, *reqbp;
 421         off_t origoffset;
 422         off_t doffset;
 423         int i;
 424         int maxra;
 425         int maxrbuild;
 426
 427         /*
 428          * Calculate the desired read-ahead in blksize'd blocks (maxra).
 429          * To do this we calculate maxreq.
 430          *
 431          * maxreq typically starts out as a sequential heuristic.  If the
 432          * high level uio/resid is bigger (minreq), we pop maxreq up to
 433          * minreq.  This represents the case where random I/O is being
 434          * performed by the userland is issuing big read()'s.
 435          *
 436          * Then we limit maxreq to max_readahead to ensure it is a reasonable
 437          * value.
 438          *
 439          * Finally we must ensure that (loffset + maxreq) does not cross the
 440          * boundary (filesize) for the current blocksize.  If we allowed it
 441          * to cross we could end up with buffers past the boundary with the
 442          * wrong block size (HAMMER large-data areas use mixed block sizes).
 443          * minreq is also absolutely limited to filesize.
 444          */
 445         if (maxreq < minreq)
 446                 maxreq = minreq;
 447         /* minreq not used beyond this point */
 448
 449         if (maxreq > max_readahead) {
 450                 maxreq = max_readahead;
 451                 if (maxreq > 16 * 1024 * 1024)
 452                         maxreq = 16 * 1024 * 1024;
 453         }
 454         if (maxreq < blksize)
 455                 maxreq = blksize;
 456         if (loffset + maxreq > filesize) {
 457                 if (loffset > filesize)
 458                         maxreq = 0;
 459                 else
 460                         maxreq = filesize - loffset;
 461         }
 462
 463         maxra = (int)(maxreq / blksize);
 464
 465         /*
 466          * Get the requested block.
 467          */
 468         reqbp = bp = getblk(vp, loffset, blksize, 0, 0);
 469         origoffset = loffset;
 470
 471         /*
 472          * Calculate the maximum cluster size for a single I/O, used
 473          * by cluster_rbuild().
 474          */
 475         maxrbuild = vmaxiosize(vp) / blksize;
 476
 477         /*
 478          * if it is in the cache, then check to see if the reads have been
 479          * sequential.  If they have, then try some read-ahead, otherwise
 480          * back-off on prospective read-aheads.
 481          */
 482         if (bp->b_flags & B_CACHE) {
 483                 /*
 484                  * Setup for func() call whether we do read-ahead or not.
 485                  */
 486                 bp->b_bio1.bio_caller_info1.ptr = arg;
 487                 bp->b_bio1.bio_flags |= BIO_DONE;
 488
 489                 /*
 490                  * Not sequential, do not do any read-ahead
 491                  */
 492                 if (maxra <= 1)
 493                         goto no_read_ahead;
 494
 495                 /*
 496                  * No read-ahead mark, do not do any read-ahead
 497                  * yet.
 498                  */
 499                 if ((bp->b_flags & B_RAM) == 0)
 500                         goto no_read_ahead;
 501                 bp->b_flags &= ~B_RAM;
 502
 503                 /*
 504                  * We hit a read-ahead-mark, figure out how much read-ahead
 505                  * to do (maxra) and where to start (loffset).
 506                  *
 507                  * Shortcut the scan.  Typically the way this works is that
 508                  * we've built up all the blocks inbetween except for the
 509                  * last in previous iterations, so if the second-to-last
 510                  * block is present we just skip ahead to it.
 511                  *
 512                  * This algorithm has O(1) cpu in the steady state no
 513                  * matter how large maxra is.
 514                  */
 515                 if (findblk(vp, loffset + (maxra - 2) * blksize, FINDBLK_TEST))
 516                         i = maxra - 1;
 517                 else
 518                         i = 1;
 519                 while (i < maxra) {
 520                         if (findblk(vp, loffset + i * blksize,
 521                                     FINDBLK_TEST) == NULL) {
 522                                 break;
 523                         }
 524                         ++i;
 525                 }
 526
 527                 /*
 528                  * We got everything or everything is in the cache, no
 529                  * point continuing.
 530                  */
 531                 if (i >= maxra)
 532                         goto no_read_ahead;
 533
 534                 /*
 535                  * Calculate where to start the read-ahead and how much
 536                  * to do.  Generally speaking we want to read-ahead by
 537                  * (maxra) when we've found a read-ahead mark.  We do
 538                  * not want to reduce maxra here as it will cause
 539                  * successive read-ahead I/O's to be smaller and smaller.
 540                  *
 541                  * However, we have to make sure we don't break the
 542                  * filesize limitation for the clustered operation.
 543                  */
 544                 loffset += i * blksize;
 545                 bp = NULL;
 546                 /* leave reqbp intact to force function callback */
 547
 548                 if (loffset >= filesize)
 549                         goto no_read_ahead;
 550                 if (loffset + maxra * blksize > filesize) {
 551                         maxreq = filesize - loffset;
 552                         maxra = (int)(maxreq / blksize);
 553                 }
 554         } else {
 555                 __debugvar off_t firstread = bp->b_loffset;
 556                 int nblks;
 557                 int tmp_error;
 558
 559                 /*
 560                  * Set-up synchronous read for bp.
 561                  */
 562                 bp->b_flags &= ~(B_ERROR | B_EINTR | B_INVAL);
 563                 bp->b_cmd = BUF_CMD_READ;
 564                 bp->b_bio1.bio_done = func;
 565                 bp->b_bio1.bio_caller_info1.ptr = arg;
 566                 BUF_KERNPROC(bp);
 567                 reqbp = NULL;   /* don't func() reqbp, it's running async */
 568
 569                 KASSERT(firstread != NOOFFSET,
 570                         ("cluster_read: no buffer offset"));
 571
 572                 /*
 573                  * nblks is our cluster_rbuild request size, limited
 574                  * primarily by the device.
 575                  */
 576                 if ((nblks = maxra) > maxrbuild)
 577                         nblks = maxrbuild;
 578
 579                 if (nblks > 1) {
 580                         int burstbytes;
 581
 582                         tmp_error = VOP_BMAP(vp, loffset, &doffset,
 583                                              &burstbytes, NULL, BUF_CMD_READ);
 584                         if (tmp_error)
 585                                 goto single_block_read;
 586                         if (nblks > burstbytes / blksize)
 587                                 nblks = burstbytes / blksize;
 588                         if (doffset == NOOFFSET)
 589                                 goto single_block_read;
 590                         if (nblks <= 1)
 591                                 goto single_block_read;
 592
 593                         bp = cluster_rbuild(vp, filesize, loffset,
 594                                             doffset, blksize, nblks, bp);
 595                         loffset += bp->b_bufsize;
 596                         maxra -= bp->b_bufsize / blksize;
 597                 } else {
 598 single_block_read:
 599                         /*
 600                          * If it isn't in the cache, then get a chunk from
 601                          * disk if sequential, otherwise just get the block.
 602                          */
 603                         cluster_setram(bp);
 604                         loffset += blksize;
 605                         --maxra;
 606                 }
 607         }
 608
 609         /*
 610          * If bp != NULL then B_CACHE was *NOT* set and bp must be issued.
 611          * bp will either be an asynchronous cluster buf or an asynchronous
 612          * single-buf.
 613          *
 614          * NOTE: Once an async cluster buf is issued bp becomes invalid.
 615          */
 616         if (bp) {
 617 #if defined(CLUSTERDEBUG)
 618                 if (rcluster)
 619                         kprintf("S(%012jx,%d,%d)\n",
 620                             (intmax_t)bp->b_loffset, bp->b_bcount, maxra);
 621 #endif
 622                 if ((bp->b_flags & B_CLUSTER) == 0)
 623                         vfs_busy_pages(vp, bp);
 624                 bp->b_flags &= ~(B_ERROR|B_INVAL);
 625                 vn_strategy(vp, &bp->b_bio1);
 626                 /* bp invalid now */
 627                 bp = NULL;
 628         }
 629
 630         /*
 631          * If we have been doing sequential I/O, then do some read-ahead.
 632          * The code above us should have positioned us at the next likely
 633          * offset.
 634          *
 635          * Only mess with buffers which we can immediately lock.  HAMMER
 636          * will do device-readahead irrespective of what the blocks
 637          * represent.
 638          */
 639         while (maxra > 0) {
 640                 int burstbytes;
 641                 int tmp_error;
 642                 int nblks;
 643
 644                 rbp = getblk(vp, loffset, blksize,
 645                              GETBLK_SZMATCH|GETBLK_NOWAIT, 0);
 646                 if (rbp == NULL)
 647                         goto no_read_ahead;
 648                 if ((rbp->b_flags & B_CACHE)) {
 649                         bqrelse(rbp);
 650                         goto no_read_ahead;
 651                 }
 652
 653                 /*
 654                  * An error from the read-ahead bmap has nothing to do
 655                  * with the caller's original request.
 656                  */
 657                 tmp_error = VOP_BMAP(vp, loffset, &doffset,
 658                                      &burstbytes, NULL, BUF_CMD_READ);
 659                 if (tmp_error || doffset == NOOFFSET) {
 660                         rbp->b_flags |= B_INVAL;
 661                         brelse(rbp);
 662                         rbp = NULL;
 663                         goto no_read_ahead;
 664                 }
 665                 if ((nblks = maxra) > maxrbuild)
 666                         nblks = maxrbuild;
 667                 if (nblks > burstbytes / blksize)
 668                         nblks = burstbytes / blksize;
 669
 670                 /*
 671                  * rbp: async read
 672                  */
 673                 rbp->b_cmd = BUF_CMD_READ;
 674                 /*rbp->b_flags |= B_AGE*/;
 675                 cluster_setram(rbp);
 676
 677                 if (nblks > 1) {
 678                         rbp = cluster_rbuild(vp, filesize, loffset,
 679                                              doffset, blksize,
 680                                              nblks, rbp);
 681                 } else {
 682                         rbp->b_bio2.bio_offset = doffset;
 683                 }
 684
 685                 rbp->b_flags &= ~(B_ERROR|B_INVAL);
 686
 687                 if ((rbp->b_flags & B_CLUSTER) == 0)
 688                         vfs_busy_pages(vp, rbp);
 689                 BUF_KERNPROC(rbp);
 690                 loffset += rbp->b_bufsize;
 691                 maxra -= rbp->b_bufsize / blksize;
 692                 vn_strategy(vp, &rbp->b_bio1);
 693                 /* rbp invalid now */
 694         }
 695
 696         /*
 697          * If reqbp is non-NULL it had B_CACHE set and we issue the
 698          * function callback synchronously.
 699          *
 700          * Note that we may start additional asynchronous I/O before doing
 701          * the func() callback for the B_CACHE case
 702          */
 703 no_read_ahead:
 704         if (reqbp)
 705                 func(&reqbp->b_bio1);
 706 }
 707
 708 /*
 709  * If blocks are contiguous on disk, use this to provide clustered
 710  * read ahead.  We will read as many blocks as possible sequentially
 711  * and then parcel them up into logical blocks in the buffer hash table.
 712  *
 713  * This function either returns a cluster buf or it returns fbp.  fbp is
 714  * already expected to be set up as a synchronous or asynchronous request.
 715  *
 716  * If a cluster buf is returned it will always be async.
 717  */
 718 static struct buf *
 719 cluster_rbuild(struct vnode *vp, off_t filesize, off_t loffset, off_t doffset,
 720                int blksize, int run, struct buf *fbp)
 721 {
 722         struct buf *bp, *tbp;
 723         off_t boffset;
 724         int i, j;
 725         int maxiosize = vmaxiosize(vp);
 726
 727         /*
 728          * avoid a division
 729          */
 730         while (loffset + run * blksize > filesize) {
 731                 --run;
 732         }
 733
 734         tbp = fbp;
 735         tbp->b_bio2.bio_offset = doffset;
 736         if((tbp->b_flags & B_MALLOC) ||
 737             ((tbp->b_flags & B_VMIO) == 0) || (run <= 1)) {
 738                 return tbp;
 739         }
 740
 741         bp = trypbuf_kva(&cluster_pbuf_freecnt);
 742         if (bp == NULL) {
 743                 return tbp;
 744         }
 745
 746         /*
 747          * We are synthesizing a buffer out of vm_page_t's, but
 748          * if the block size is not page aligned then the starting
 749          * address may not be either.  Inherit the b_data offset
 750          * from the original buffer.
 751          */
 752         bp->b_data = (char *)((vm_offset_t)bp->b_data |
 753             ((vm_offset_t)tbp->b_data & PAGE_MASK));
 754         bp->b_flags |= B_CLUSTER | B_VMIO;
 755         bp->b_cmd = BUF_CMD_READ;
 756         bp->b_bio1.bio_done = cluster_callback;         /* default to async */
 757         bp->b_bio1.bio_caller_info1.cluster_head = NULL;
 758         bp->b_bio1.bio_caller_info2.cluster_tail = NULL;
 759         bp->b_loffset = loffset;
 760         bp->b_bio2.bio_offset = doffset;
 761         KASSERT(bp->b_loffset != NOOFFSET,
 762                 ("cluster_rbuild: no buffer offset"));
 763
 764         bp->b_bcount = 0;
 765         bp->b_bufsize = 0;
 766         bp->b_xio.xio_npages = 0;
 767
 768         for (boffset = doffset, i = 0; i < run; ++i, boffset += blksize) {
 769                 if (i) {
 770                         if ((bp->b_xio.xio_npages * PAGE_SIZE) +
 771                             round_page(blksize) > maxiosize) {
 772                                 break;
 773                         }
 774
 775                         /*
 776                          * Shortcut some checks and try to avoid buffers that
 777                          * would block in the lock.  The same checks have to
 778                          * be made again after we officially get the buffer.
 779                          */
 780                         tbp = getblk(vp, loffset + i * blksize, blksize,
 781                                      GETBLK_SZMATCH|GETBLK_NOWAIT, 0);
 782                         if (tbp == NULL)
 783                                 break;
 784                         for (j = 0; j < tbp->b_xio.xio_npages; j++) {
 785                                 if (tbp->b_xio.xio_pages[j]->valid)
 786                                         break;
 787                         }
 788                         if (j != tbp->b_xio.xio_npages) {
 789                                 bqrelse(tbp);
 790                                 break;
 791                         }
 792
 793                         /*
 794                          * Stop scanning if the buffer is fuly valid
 795                          * (marked B_CACHE), or locked (may be doing a
 796                          * background write), or if the buffer is not
 797                          * VMIO backed.  The clustering code can only deal
 798                          * with VMIO-backed buffers.
 799                          */
 800                         if ((tbp->b_flags & (B_CACHE|B_LOCKED)) ||
 801                             (tbp->b_flags & B_VMIO) == 0 ||
 802                             (LIST_FIRST(&tbp->b_dep) != NULL &&
 803                              buf_checkread(tbp))
 804                         ) {
 805                                 bqrelse(tbp);
 806                                 break;
 807                         }
 808
 809                         /*
 810                          * The buffer must be completely invalid in order to
 811                          * take part in the cluster.  If it is partially valid
 812                          * then we stop.
 813                          */
 814                         for (j = 0;j < tbp->b_xio.xio_npages; j++) {
 815                                 if (tbp->b_xio.xio_pages[j]->valid)
 816                                         break;
 817                         }
 818                         if (j != tbp->b_xio.xio_npages) {
 819                                 bqrelse(tbp);
 820                                 break;
 821                         }
 822
 823                         /*
 824                          * Set a read-ahead mark as appropriate.  Always
 825                          * set the read-ahead mark at (run - 1).  It is
 826                          * unclear why we were also setting it at i == 1.
 827                          */
 828                         if (/*i == 1 ||*/ i == (run - 1))
 829                                 cluster_setram(tbp);
 830
 831                         /*
 832                          * Depress the priority of buffers not explicitly
 833                          * requested.
 834                          */
 835                         /* tbp->b_flags |= B_AGE; */
 836
 837                         /*
 838                          * Set the block number if it isn't set, otherwise
 839                          * if it is make sure it matches the block number we
 840                          * expect.
 841                          */
 842                         if (tbp->b_bio2.bio_offset == NOOFFSET) {
 843                                 tbp->b_bio2.bio_offset = boffset;
 844                         } else if (tbp->b_bio2.bio_offset != boffset) {
 845                                 brelse(tbp);
 846                                 break;
 847                         }
 848                 }
 849
 850                 /*
 851                  * The passed-in tbp (i == 0) will already be set up for
 852                  * async or sync operation.  All other tbp's acquire in
 853                  * our loop are set up for async operation.
 854                  */
 855                 tbp->b_cmd = BUF_CMD_READ;
 856                 BUF_KERNPROC(tbp);
 857                 cluster_append(&bp->b_bio1, tbp);
 858                 for (j = 0; j < tbp->b_xio.xio_npages; ++j) {
 859                         vm_page_t m;
 860
 861                         m = tbp->b_xio.xio_pages[j];
 862                         vm_page_busy_wait(m, FALSE, "clurpg");
 863                         vm_page_io_start(m);
 864                         vm_page_wakeup(m);
 865                         vm_object_pip_add(m->object, 1);
 866                         if ((bp->b_xio.xio_npages == 0) ||
 867                                 (bp->b_xio.xio_pages[bp->b_xio.xio_npages-1] != m)) {
 868                                 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m;
 869                                 bp->b_xio.xio_npages++;
 870                         }
 871                         if ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL)
 872                                 tbp->b_xio.xio_pages[j] = bogus_page;
 873                 }
 874                 /*
 875                  * XXX shouldn't this be += size for both, like in
 876                  * cluster_wbuild()?
 877                  *
 878                  * Don't inherit tbp->b_bufsize as it may be larger due to
 879                  * a non-page-aligned size.  Instead just aggregate using
 880                  * 'size'.
 881                  */
 882                 if (tbp->b_bcount != blksize)
 883                     kprintf("warning: tbp->b_bcount wrong %d vs %d\n", tbp->b_bcount, blksize);
 884                 if (tbp->b_bufsize != blksize)
 885                     kprintf("warning: tbp->b_bufsize wrong %d vs %d\n", tbp->b_bufsize, blksize);
 886                 bp->b_bcount += blksize;
 887                 bp->b_bufsize += blksize;
 888         }
 889
 890         /*
 891          * Fully valid pages in the cluster are already good and do not need
 892          * to be re-read from disk.  Replace the page with bogus_page
 893          */
 894         for (j = 0; j < bp->b_xio.xio_npages; j++) {
 895                 if ((bp->b_xio.xio_pages[j]->valid & VM_PAGE_BITS_ALL) ==
 896                     VM_PAGE_BITS_ALL) {
 897                         bp->b_xio.xio_pages[j] = bogus_page;
 898                 }
 899         }
 900         if (bp->b_bufsize > bp->b_kvasize) {
 901                 panic("cluster_rbuild: b_bufsize(%d) > b_kvasize(%d)",
 902                     bp->b_bufsize, bp->b_kvasize);
 903         }
 904         pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
 905                 (vm_page_t *)bp->b_xio.xio_pages, bp->b_xio.xio_npages);
 906         BUF_KERNPROC(bp);
 907         return (bp);
 908 }
 909
 910 /*
 911  * Cleanup after a clustered read or write.
 912  * This is complicated by the fact that any of the buffers might have
 913  * extra memory (if there were no empty buffer headers at allocbuf time)
 914  * that we will need to shift around.
 915  *
 916  * The returned bio is &bp->b_bio1
 917  */
 918 void
 919 cluster_callback(struct bio *bio)
 920 {
 921         struct buf *bp = bio->bio_buf;
 922         struct buf *tbp;
 923         int error = 0;
 924
 925         /*
 926          * Must propogate errors to all the components.  A short read (EOF)
 927          * is a critical error.
 928          */
 929         if (bp->b_flags & B_ERROR) {
 930                 error = bp->b_error;
 931         } else if (bp->b_bcount != bp->b_bufsize) {
 932                 panic("cluster_callback: unexpected EOF on cluster %p!", bio);
 933         }
 934
 935         pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_xio.xio_npages);
 936         /*
 937          * Move memory from the large cluster buffer into the component
 938          * buffers and mark IO as done on these.  Since the memory map
 939          * is the same, no actual copying is required.
 940          */
 941         while ((tbp = bio->bio_caller_info1.cluster_head) != NULL) {
 942                 bio->bio_caller_info1.cluster_head = tbp->b_cluster_next;
 943                 if (error) {
 944                         tbp->b_flags |= B_ERROR | B_IODEBUG;
 945                         tbp->b_error = error;
 946                 } else {
 947                         tbp->b_dirtyoff = tbp->b_dirtyend = 0;
 948                         tbp->b_flags &= ~(B_ERROR|B_INVAL);
 949                         tbp->b_flags |= B_IODEBUG;
 950                         /*
 951                          * XXX the bdwrite()/bqrelse() issued during
 952                          * cluster building clears B_RELBUF (see bqrelse()
 953                          * comment).  If direct I/O was specified, we have
 954                          * to restore it here to allow the buffer and VM
 955                          * to be freed.
 956                          */
 957                         if (tbp->b_flags & B_DIRECT)
 958                                 tbp->b_flags |= B_RELBUF;
 959                 }
 960                 biodone(&tbp->b_bio1);
 961         }
 962         relpbuf(bp, &cluster_pbuf_freecnt);
 963 }
 964
 965 /*
 966  * Implement modified write build for cluster.
 967  *
 968  *      write_behind = 0        write behind disabled
 969  *      write_behind = 1        write behind normal (default)
 970  *      write_behind = 2        write behind backed-off
 971  *
 972  * In addition, write_behind is only activated for files that have
 973  * grown past a certain size (default 10MB).  Otherwise temporary files
 974  * wind up generating a lot of unnecessary disk I/O.
 975  */
 976 static __inline int
 977 cluster_wbuild_wb(struct vnode *vp, int blksize, off_t start_loffset, int len)
 978 {
 979         int r = 0;
 980
 981         switch(write_behind) {
 982         case 2:
 983                 if (start_loffset < len)
 984                         break;
 985                 start_loffset -= len;
 986                 /* fall through */
 987         case 1:
 988                 if (vp->v_filesize >= write_behind_minfilesize) {
 989                         r = cluster_wbuild(vp, NULL, blksize,
 990                                            start_loffset, len);
 991                 }
 992                 /* fall through */
 993         default:
 994                 /* fall through */
 995                 break;
 996         }
 997         return(r);
 998 }
 999
1000 /*
1001  * Do clustered write for FFS.
1002  *
1003  * Three cases:
1004  *      1. Write is not sequential (write asynchronously)
1005  *      Write is sequential:
1006  *      2.      beginning of cluster - begin cluster
1007  *      3.      middle of a cluster - add to cluster
1008  *      4.      end of a cluster - asynchronously write cluster
1009  */
1010 void
1011 cluster_write(struct buf *bp, off_t filesize, int blksize, int seqcount)
1012 {
1013         struct vnode *vp;
1014         off_t loffset;
1015         int maxclen, cursize;
1016         int async;
1017
1018         vp = bp->b_vp;
1019         if (vp->v_type == VREG)
1020                 async = vp->v_mount->mnt_flag & MNT_ASYNC;
1021         else
1022                 async = 0;
1023         loffset = bp->b_loffset;
1024         KASSERT(bp->b_loffset != NOOFFSET,
1025                 ("cluster_write: no buffer offset"));
1026
1027         /* Initialize vnode to beginning of file. */
1028         if (loffset == 0)
1029                 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0;
1030
1031         if (vp->v_clen == 0 || loffset != vp->v_lastw + blksize ||
1032             bp->b_bio2.bio_offset == NOOFFSET ||
1033             (bp->b_bio2.bio_offset != vp->v_lasta + blksize)) {
1034                 maxclen = vmaxiosize(vp);
1035                 if (vp->v_clen != 0) {
1036                         /*
1037                          * Next block is not sequential.
1038                          *
1039                          * If we are not writing at end of file, the process
1040                          * seeked to another point in the file since its last
1041                          * write, or we have reached our maximum cluster size,
1042                          * then push the previous cluster. Otherwise try
1043                          * reallocating to make it sequential.
1044                          *
1045                          * Change to algorithm: only push previous cluster if
1046                          * it was sequential from the point of view of the
1047                          * seqcount heuristic, otherwise leave the buffer
1048                          * intact so we can potentially optimize the I/O
1049                          * later on in the buf_daemon or update daemon
1050                          * flush.
1051                          */
1052                         cursize = vp->v_lastw - vp->v_cstart + blksize;
1053                         if (bp->b_loffset + blksize < filesize ||
1054                             loffset != vp->v_lastw + blksize || vp->v_clen <= cursize) {
1055                                 if (!async && seqcount > 0) {
1056                                         cluster_wbuild_wb(vp, blksize,
1057                                                 vp->v_cstart, cursize);
1058                                 }
1059                         } else {
1060                                 struct buf **bpp, **endbp;
1061                                 struct cluster_save *buflist;
1062
1063                                 buflist = cluster_collectbufs(vp, bp, blksize);
1064                                 endbp = &buflist->bs_children
1065                                     [buflist->bs_nchildren - 1];
1066                                 if (VOP_REALLOCBLKS(vp, buflist)) {
1067                                         /*
1068                                          * Failed, push the previous cluster
1069                                          * if *really* writing sequentially
1070                                          * in the logical file (seqcount > 1),
1071                                          * otherwise delay it in the hopes that
1072                                          * the low level disk driver can
1073                                          * optimize the write ordering.
1074                                          */
1075                                         for (bpp = buflist->bs_children;
1076                                              bpp < endbp; bpp++)
1077                                                 brelse(*bpp);
1078                                         kfree(buflist, M_SEGMENT);
1079                                         if (seqcount > 1) {
1080                                                 cluster_wbuild_wb(vp,
1081                                                     blksize, vp->v_cstart,
1082                                                     cursize);
1083                                         }
1084                                 } else {
1085                                         /*
1086                                          * Succeeded, keep building cluster.
1087                                          */
1088                                         for (bpp = buflist->bs_children;
1089                                              bpp <= endbp; bpp++)
1090                                                 bdwrite(*bpp);
1091                                         kfree(buflist, M_SEGMENT);
1092                                         vp->v_lastw = loffset;
1093                                         vp->v_lasta = bp->b_bio2.bio_offset;
1094                                         return;
1095                                 }
1096                         }
1097                 }
1098                 /*
1099                  * Consider beginning a cluster. If at end of file, make
1100                  * cluster as large as possible, otherwise find size of
1101                  * existing cluster.
1102                  */
1103                 if ((vp->v_type == VREG) &&
1104                     bp->b_loffset + blksize < filesize &&
1105                     (bp->b_bio2.bio_offset == NOOFFSET) &&
1106                     (VOP_BMAP(vp, loffset, &bp->b_bio2.bio_offset, &maxclen, NULL, BUF_CMD_WRITE) ||
1107                      bp->b_bio2.bio_offset == NOOFFSET)) {
1108                         bdwrite(bp);
1109                         vp->v_clen = 0;
1110                         vp->v_lasta = bp->b_bio2.bio_offset;
1111                         vp->v_cstart = loffset + blksize;
1112                         vp->v_lastw = loffset;
1113                         return;
1114                 }
1115                 if (maxclen > blksize)
1116                         vp->v_clen = maxclen - blksize;
1117                 else
1118                         vp->v_clen = 0;
1119                 if (!async && vp->v_clen == 0) { /* I/O not contiguous */
1120                         vp->v_cstart = loffset + blksize;
1121                         bdwrite(bp);
1122                 } else {        /* Wait for rest of cluster */
1123                         vp->v_cstart = loffset;
1124                         bdwrite(bp);
1125                 }
1126         } else if (loffset == vp->v_cstart + vp->v_clen) {
1127                 /*
1128                  * At end of cluster, write it out if seqcount tells us we
1129                  * are operating sequentially, otherwise let the buf or
1130                  * update daemon handle it.
1131                  */
1132                 bdwrite(bp);
1133                 if (seqcount > 1)
1134                         cluster_wbuild_wb(vp, blksize, vp->v_cstart,
1135                                           vp->v_clen + blksize);
1136                 vp->v_clen = 0;
1137                 vp->v_cstart = loffset + blksize;
1138         } else if (vm_page_count_severe() &&
1139                    bp->b_loffset + blksize < filesize) {
1140                 /*
1141                  * We are low on memory, get it going NOW.  However, do not
1142                  * try to push out a partial block at the end of the file
1143                  * as this could lead to extremely non-optimal write activity.
1144                  */
1145                 bawrite(bp);
1146         } else {
1147                 /*
1148                  * In the middle of a cluster, so just delay the I/O for now.
1149                  */
1150                 bdwrite(bp);
1151         }
1152         vp->v_lastw = loffset;
1153         vp->v_lasta = bp->b_bio2.bio_offset;
1154 }
1155
1156 /*
1157  * This is the clustered version of bawrite().  It works similarly to
1158  * cluster_write() except I/O on the buffer is guaranteed to occur.
1159  */
1160 int
1161 cluster_awrite(struct buf *bp)
1162 {
1163         int total;
1164
1165         /*
1166          * Don't bother if it isn't clusterable.
1167          */
1168         if ((bp->b_flags & B_CLUSTEROK) == 0 ||
1169             bp->b_vp == NULL ||
1170             (bp->b_vp->v_flag & VOBJBUF) == 0) {
1171                 total = bp->b_bufsize;
1172                 bawrite(bp);
1173                 return (total);
1174         }
1175
1176         total = cluster_wbuild(bp->b_vp, &bp, bp->b_bufsize,
1177                                bp->b_loffset, vmaxiosize(bp->b_vp));
1178         if (bp)
1179                 bawrite(bp);
1180
1181         return total;
1182 }
1183
1184 /*
1185  * This is an awful lot like cluster_rbuild...wish they could be combined.
1186  * The last lbn argument is the current block on which I/O is being
1187  * performed.  Check to see that it doesn't fall in the middle of
1188  * the current block (if last_bp == NULL).
1189  *
1190  * cluster_wbuild() normally does not guarantee anything.  If bpp is
1191  * non-NULL and cluster_wbuild() is able to incorporate it into the
1192  * I/O it will set *bpp to NULL, otherwise it will leave it alone and
1193  * the caller must dispose of *bpp.
1194  */
1195 static int
1196 cluster_wbuild(struct vnode *vp, struct buf **bpp,
1197                int blksize, off_t start_loffset, int bytes)
1198 {
1199         struct buf *bp, *tbp;
1200         int i, j;
1201         int totalwritten = 0;
1202         int must_initiate;
1203         int maxiosize = vmaxiosize(vp);
1204
1205         while (bytes > 0) {
1206                 /*
1207                  * If the buffer matches the passed locked & removed buffer
1208                  * we used the passed buffer (which might not be B_DELWRI).
1209                  *
1210                  * Otherwise locate the buffer and determine if it is
1211                  * compatible.
1212                  */
1213                 if (bpp && (*bpp)->b_loffset == start_loffset) {
1214                         tbp = *bpp;
1215                         *bpp = NULL;
1216                         bpp = NULL;
1217                 } else {
1218                         tbp = findblk(vp, start_loffset, FINDBLK_NBLOCK);
1219                         if (tbp == NULL ||
1220                             (tbp->b_flags & (B_LOCKED | B_INVAL | B_DELWRI)) !=
1221                              B_DELWRI ||
1222                             (LIST_FIRST(&tbp->b_dep) && buf_checkwrite(tbp))) {
1223                                 if (tbp)
1224                                         BUF_UNLOCK(tbp);
1225                                 start_loffset += blksize;
1226                                 bytes -= blksize;
1227                                 continue;
1228                         }
1229                         bremfree(tbp);
1230                 }
1231                 KKASSERT(tbp->b_cmd == BUF_CMD_DONE);
1232
1233                 /*
1234                  * Extra memory in the buffer, punt on this buffer.
1235                  * XXX we could handle this in most cases, but we would
1236                  * have to push the extra memory down to after our max
1237                  * possible cluster size and then potentially pull it back
1238                  * up if the cluster was terminated prematurely--too much
1239                  * hassle.
1240                  */
1241                 if (((tbp->b_flags & (B_CLUSTEROK|B_MALLOC)) != B_CLUSTEROK) ||
1242                     (tbp->b_bcount != tbp->b_bufsize) ||
1243                     (tbp->b_bcount != blksize) ||
1244                     (bytes == blksize) ||
1245                     ((bp = getpbuf_kva(&cluster_pbuf_freecnt)) == NULL)) {
1246                         totalwritten += tbp->b_bufsize;
1247                         bawrite(tbp);
1248                         start_loffset += blksize;
1249                         bytes -= blksize;
1250                         continue;
1251                 }
1252
1253                 /*
1254                  * Set up the pbuf.  Track our append point with b_bcount
1255                  * and b_bufsize.  b_bufsize is not used by the device but
1256                  * our caller uses it to loop clusters and we use it to
1257                  * detect a premature EOF on the block device.
1258                  */
1259                 bp->b_bcount = 0;
1260                 bp->b_bufsize = 0;
1261                 bp->b_xio.xio_npages = 0;
1262                 bp->b_loffset = tbp->b_loffset;
1263                 bp->b_bio2.bio_offset = tbp->b_bio2.bio_offset;
1264
1265                 /*
1266                  * We are synthesizing a buffer out of vm_page_t's, but
1267                  * if the block size is not page aligned then the starting
1268                  * address may not be either.  Inherit the b_data offset
1269                  * from the original buffer.
1270                  */
1271                 bp->b_data = (char *)((vm_offset_t)bp->b_data |
1272                     ((vm_offset_t)tbp->b_data & PAGE_MASK));
1273                 bp->b_flags &= ~B_ERROR;
1274                 bp->b_flags |= B_CLUSTER | B_BNOCLIP |
1275                         (tbp->b_flags & (B_VMIO | B_NEEDCOMMIT));
1276                 bp->b_bio1.bio_caller_info1.cluster_head = NULL;
1277                 bp->b_bio1.bio_caller_info2.cluster_tail = NULL;
1278
1279                 /*
1280                  * From this location in the file, scan forward to see
1281                  * if there are buffers with adjacent data that need to
1282                  * be written as well.
1283                  *
1284                  * IO *must* be initiated on index 0 at this point
1285                  * (particularly when called from cluster_awrite()).
1286                  */
1287                 for (i = 0; i < bytes; (i += blksize), (start_loffset += blksize)) {
1288                         if (i == 0) {
1289                                 must_initiate = 1;
1290                         } else {
1291                                 /*
1292                                  * Not first buffer.
1293                                  */
1294                                 must_initiate = 0;
1295                                 tbp = findblk(vp, start_loffset,
1296                                               FINDBLK_NBLOCK);
1297                                 /*
1298                                  * Buffer not found or could not be locked
1299                                  * non-blocking.
1300                                  */
1301                                 if (tbp == NULL)
1302                                         break;
1303
1304                                 /*
1305                                  * If it IS in core, but has different
1306                                  * characteristics, then don't cluster
1307                                  * with it.
1308                                  */
1309                                 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK |
1310                                      B_INVAL | B_DELWRI | B_NEEDCOMMIT))
1311                                     != (B_DELWRI | B_CLUSTEROK |
1312                                      (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) ||
1313                                     (tbp->b_flags & B_LOCKED)
1314                                 ) {
1315                                         BUF_UNLOCK(tbp);
1316                                         break;
1317                                 }
1318
1319                                 /*
1320                                  * Check that the combined cluster
1321                                  * would make sense with regard to pages
1322                                  * and would not be too large
1323                                  *
1324                                  * WARNING! buf_checkwrite() must be the last
1325                                  *          check made.  If it returns 0 then
1326                                  *          we must initiate the I/O.
1327                                  */
1328                                 if ((tbp->b_bcount != blksize) ||
1329                                   ((bp->b_bio2.bio_offset + i) !=
1330                                     tbp->b_bio2.bio_offset) ||
1331                                   ((tbp->b_xio.xio_npages + bp->b_xio.xio_npages) >
1332                                     (maxiosize / PAGE_SIZE)) ||
1333                                   (LIST_FIRST(&tbp->b_dep) &&
1334                                    buf_checkwrite(tbp))
1335                                 ) {
1336                                         BUF_UNLOCK(tbp);
1337                                         break;
1338                                 }
1339                                 if (LIST_FIRST(&tbp->b_dep))
1340                                         must_initiate = 1;
1341                                 /*
1342                                  * Ok, it's passed all the tests,
1343                                  * so remove it from the free list
1344                                  * and mark it busy. We will use it.
1345                                  */
1346                                 bremfree(tbp);
1347                                 KKASSERT(tbp->b_cmd == BUF_CMD_DONE);
1348                         }
1349
1350                         /*
1351                          * If the IO is via the VM then we do some
1352                          * special VM hackery (yuck).  Since the buffer's
1353                          * block size may not be page-aligned it is possible
1354                          * for a page to be shared between two buffers.  We
1355                          * have to get rid of the duplication when building
1356                          * the cluster.
1357                          */
1358                         if (tbp->b_flags & B_VMIO) {
1359                                 vm_page_t m;
1360
1361                                 /*
1362                                  * Try to avoid deadlocks with the VM system.
1363                                  * However, we cannot abort the I/O if
1364                                  * must_initiate is non-zero.
1365                                  */
1366                                 if (must_initiate == 0) {
1367                                         for (j = 0;
1368                                              j < tbp->b_xio.xio_npages;
1369                                              ++j) {
1370                                                 m = tbp->b_xio.xio_pages[j];
1371                                                 if (m->flags & PG_BUSY) {
1372                                                         bqrelse(tbp);
1373                                                         goto finishcluster;
1374                                                 }
1375                                         }
1376                                 }
1377
1378                                 for (j = 0; j < tbp->b_xio.xio_npages; ++j) {
1379                                         m = tbp->b_xio.xio_pages[j];
1380                                         vm_page_busy_wait(m, FALSE, "clurpg");
1381                                         vm_page_io_start(m);
1382                                         vm_page_wakeup(m);
1383                                         vm_object_pip_add(m->object, 1);
1384                                         if ((bp->b_xio.xio_npages == 0) ||
1385                                           (bp->b_xio.xio_pages[bp->b_xio.xio_npages - 1] != m)) {
1386                                                 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m;
1387                                                 bp->b_xio.xio_npages++;
1388                                         }
1389                                 }
1390                         }
1391                         bp->b_bcount += blksize;
1392                         bp->b_bufsize += blksize;
1393
1394                         bundirty(tbp);
1395                         tbp->b_flags &= ~B_ERROR;
1396                         tbp->b_cmd = BUF_CMD_WRITE;
1397                         BUF_KERNPROC(tbp);
1398                         cluster_append(&bp->b_bio1, tbp);
1399
1400                         /*
1401                          * check for latent dependencies to be handled
1402                          */
1403                         if (LIST_FIRST(&tbp->b_dep) != NULL)
1404                                 buf_start(tbp);
1405                 }
1406         finishcluster:
1407                 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
1408                             (vm_page_t *)bp->b_xio.xio_pages,
1409                             bp->b_xio.xio_npages);
1410                 if (bp->b_bufsize > bp->b_kvasize) {
1411                         panic("cluster_wbuild: b_bufsize(%d) "
1412                               "> b_kvasize(%d)\n",
1413                               bp->b_bufsize, bp->b_kvasize);
1414                 }
1415                 totalwritten += bp->b_bufsize;
1416                 bp->b_dirtyoff = 0;
1417                 bp->b_dirtyend = bp->b_bufsize;
1418                 bp->b_bio1.bio_done = cluster_callback;
1419                 bp->b_cmd = BUF_CMD_WRITE;
1420
1421                 vfs_busy_pages(vp, bp);
1422                 bsetrunningbufspace(bp, bp->b_bufsize);
1423                 BUF_KERNPROC(bp);
1424                 vn_strategy(vp, &bp->b_bio1);
1425
1426                 bytes -= i;
1427         }
1428         return totalwritten;
1429 }
1430
1431 /*
1432  * Collect together all the buffers in a cluster, plus add one
1433  * additional buffer passed-in.
1434  *
1435  * Only pre-existing buffers whos block size matches blksize are collected.
1436  * (this is primarily because HAMMER1 uses varying block sizes and we don't
1437  * want to override its choices).
1438  */
1439 static struct cluster_save *
1440 cluster_collectbufs(struct vnode *vp, struct buf *last_bp, int blksize)
1441 {
1442         struct cluster_save *buflist;
1443         struct buf *bp;
1444         off_t loffset;
1445         int i, len;
1446         int j;
1447         int k;
1448
1449         len = (int)(vp->v_lastw - vp->v_cstart + blksize) / blksize;
1450         buflist = kmalloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist),
1451                          M_SEGMENT, M_WAITOK);
1452         buflist->bs_nchildren = 0;
1453         buflist->bs_children = (struct buf **) (buflist + 1);
1454         for (loffset = vp->v_cstart, i = 0, j = 0;
1455              i < len;
1456              (loffset += blksize), i++) {
1457                 bp = getcacheblk(vp, loffset,
1458                                  last_bp->b_bcount, GETBLK_SZMATCH);
1459                 buflist->bs_children[i] = bp;
1460                 if (bp == NULL) {
1461                         j = i + 1;
1462                 } else if (bp->b_bio2.bio_offset == NOOFFSET) {
1463                         VOP_BMAP(bp->b_vp, bp->b_loffset,
1464                                  &bp->b_bio2.bio_offset,
1465                                  NULL, NULL, BUF_CMD_WRITE);
1466                 }
1467         }
1468
1469         /*
1470          * Get rid of gaps
1471          */
1472         for (k = 0; k < j; ++k) {
1473                 if (buflist->bs_children[k]) {
1474                         bqrelse(buflist->bs_children[k]);
1475                         buflist->bs_children[k] = NULL;
1476                 }
1477         }
1478         if (j != 0) {
1479                 if (j != i) {
1480                         bcopy(buflist->bs_children + j,
1481                               buflist->bs_children + 0,
1482                               sizeof(buflist->bs_children[0]) * (i - j));
1483                 }
1484                 i -= j;
1485         }
1486         buflist->bs_children[i] = bp = last_bp;
1487         if (bp->b_bio2.bio_offset == NOOFFSET) {
1488                 VOP_BMAP(bp->b_vp, bp->b_loffset, &bp->b_bio2.bio_offset,
1489                          NULL, NULL, BUF_CMD_WRITE);
1490         }
1491         buflist->bs_nchildren = i + 1;
1492         return (buflist);
1493 }
1494
1495 void
1496 cluster_append(struct bio *bio, struct buf *tbp)
1497 {
1498         tbp->b_cluster_next = NULL;
1499         if (bio->bio_caller_info1.cluster_head == NULL) {
1500                 bio->bio_caller_info1.cluster_head = tbp;
1501                 bio->bio_caller_info2.cluster_tail = tbp;
1502         } else {
1503                 bio->bio_caller_info2.cluster_tail->b_cluster_next = tbp;
1504                 bio->bio_caller_info2.cluster_tail = tbp;
1505         }
1506 }
1507
1508 static
1509 void
1510 cluster_setram (struct buf *bp)
1511 {
1512         bp->b_flags |= B_RAM;
1513         if (bp->b_xio.xio_npages)
1514                 vm_page_flag_set(bp->b_xio.xio_pages[0], PG_RAM);
1515 }