sys/kern/vfs_cluster.c

   1 /*-
   2  * Copyright (c) 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  * Modifications/enhancements:
   5  *      Copyright (c) 1995 John S. Dyson.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. All advertising materials mentioning features or use of this software
  16  *    must display the following acknowledgement:
  17  *      This product includes software developed by the University of
  18  *      California, Berkeley and its contributors.
  19  * 4. Neither the name of the University nor the names of its contributors
  20  *    may be used to endorse or promote products derived from this software
  21  *    without specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  33  * SUCH DAMAGE.
  34  *
  35  *      @(#)vfs_cluster.c       8.7 (Berkeley) 2/13/94
  36  * $FreeBSD: src/sys/kern/vfs_cluster.c,v 1.92.2.9 2001/11/18 07:10:59 dillon Exp $
  37  * $DragonFly: src/sys/kern/vfs_cluster.c,v 1.40 2008/07/14 03:09:00 dillon Exp $
  38  */
  39
  40 #include "opt_debug_cluster.h"
  41
  42 #include <sys/param.h>
  43 #include <sys/systm.h>
  44 #include <sys/kernel.h>
  45 #include <sys/proc.h>
  46 #include <sys/buf.h>
  47 #include <sys/vnode.h>
  48 #include <sys/malloc.h>
  49 #include <sys/mount.h>
  50 #include <sys/resourcevar.h>
  51 #include <sys/vmmeter.h>
  52 #include <vm/vm.h>
  53 #include <vm/vm_object.h>
  54 #include <vm/vm_page.h>
  55 #include <sys/sysctl.h>
  56 #include <sys/buf2.h>
  57 #include <vm/vm_page2.h>
  58
  59 #include <machine/limits.h>
  60
  61 #if defined(CLUSTERDEBUG)
  62 #include <sys/sysctl.h>
  63 static int      rcluster= 0;
  64 SYSCTL_INT(_debug, OID_AUTO, rcluster, CTLFLAG_RW, &rcluster, 0, "");
  65 #endif
  66
  67 static MALLOC_DEFINE(M_SEGMENT, "cluster_save", "cluster_save buffer");
  68
  69 static struct cluster_save *
  70         cluster_collectbufs (struct vnode *vp, struct buf *last_bp,
  71                             int blksize);
  72 static struct buf *
  73         cluster_rbuild (struct vnode *vp, off_t filesize, off_t loffset,
  74                             off_t doffset, int blksize, int run,
  75                             struct buf *fbp);
  76 static void cluster_callback (struct bio *);
  77 static void cluster_setram (struct buf *);
  78
  79 static int write_behind = 1;
  80 SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0,
  81     "Cluster write-behind setting");
  82 static int max_readahead = 2 * 1024 * 1024;
  83 SYSCTL_INT(_vfs, OID_AUTO, max_readahead, CTLFLAG_RW, &max_readahead, 0,
  84     "Limit in bytes for desired cluster read-ahead");
  85
  86 extern vm_page_t        bogus_page;
  87
  88 extern int cluster_pbuf_freecnt;
  89
  90 /*
  91  * This replaces bread.
  92  *
  93  * filesize     - read-ahead @ blksize will not cross this boundary
  94  * loffset      - loffset for returned *bpp
  95  * blksize      - blocksize for returned *bpp and read-ahead bps
  96  * minreq       - minimum (not a hard minimum) in bytes, typically reflects
  97  *                a higher level uio resid.
  98  * maxreq       - maximum (sequential heuristic) in bytes (highet typ ~2MB)
  99  * bpp          - return buffer (*bpp) for (loffset,blksize)
 100  */
 101 int
 102 cluster_read(struct vnode *vp, off_t filesize, off_t loffset,
 103              int blksize, size_t minreq, size_t maxreq, struct buf **bpp)
 104 {
 105         struct buf *bp, *rbp, *reqbp;
 106         off_t origoffset;
 107         off_t doffset;
 108         int error;
 109         int i;
 110         int maxra;
 111         int maxrbuild;
 112
 113         error = 0;
 114
 115         /*
 116          * Calculate the desired read-ahead in blksize'd blocks (maxra).
 117          * To do this we calculate maxreq.
 118          *
 119          * maxreq typically starts out as a sequential heuristic.  If the
 120          * high level uio/resid is bigger (minreq), we pop maxreq up to
 121          * minreq.  This represents the case where random I/O is being
 122          * performed by the userland is issuing big read()'s.
 123          *
 124          * Then we limit maxreq to max_readahead to ensure it is a reasonable
 125          * value.
 126          *
 127          * Finally we must ensure that (loffset + maxreq) does not cross the
 128          * boundary (filesize) for the current blocksize.  If we allowed it
 129          * to cross we could end up with buffers past the boundary with the
 130          * wrong block size (HAMMER large-data areas use mixed block sizes).
 131          * minreq is also absolutely limited to filesize.
 132          */
 133         if (maxreq < minreq)
 134                 maxreq = minreq;
 135         /* minreq not used beyond this point */
 136
 137         if (maxreq > max_readahead) {
 138                 maxreq = max_readahead;
 139                 if (maxreq > 16 * 1024 * 1024)
 140                         maxreq = 16 * 1024 * 1024;
 141         }
 142         if (maxreq < blksize)
 143                 maxreq = blksize;
 144         if (loffset + maxreq > filesize) {
 145                 if (loffset > filesize)
 146                         maxreq = 0;
 147                 else
 148                         maxreq = filesize - loffset;
 149         }
 150
 151         maxra = (int)(maxreq / blksize);
 152
 153         /*
 154          * Get the requested block.
 155          */
 156         *bpp = reqbp = bp = getblk(vp, loffset, blksize, 0, 0);
 157         origoffset = loffset;
 158
 159         /*
 160          * Calculate the maximum cluster size for a single I/O, used
 161          * by cluster_rbuild().
 162          */
 163         maxrbuild = vmaxiosize(vp) / blksize;
 164
 165         /*
 166          * if it is in the cache, then check to see if the reads have been
 167          * sequential.  If they have, then try some read-ahead, otherwise
 168          * back-off on prospective read-aheads.
 169          */
 170         if (bp->b_flags & B_CACHE) {
 171                 /*
 172                  * Not sequential, do not do any read-ahead
 173                  */
 174                 if (maxra <= 1)
 175                         return 0;
 176
 177                 /*
 178                  * No read-ahead mark, do not do any read-ahead
 179                  * yet.
 180                  */
 181                 if ((bp->b_flags & B_RAM) == 0)
 182                         return 0;
 183
 184                 /*
 185                  * We hit a read-ahead-mark, figure out how much read-ahead
 186                  * to do (maxra) and where to start (loffset).
 187                  *
 188                  * Shortcut the scan.  Typically the way this works is that
 189                  * we've built up all the blocks inbetween except for the
 190                  * last in previous iterations, so if the second-to-last
 191                  * block is present we just skip ahead to it.
 192                  *
 193                  * This algorithm has O(1) cpu in the steady state no
 194                  * matter how large maxra is.
 195                  */
 196                 bp->b_flags &= ~B_RAM;
 197
 198                 if (findblk(vp, loffset + (maxra - 2) * blksize, FINDBLK_TEST))
 199                         i = maxra - 1;
 200                 else
 201                         i = 1;
 202                 while (i < maxra) {
 203                         if (findblk(vp, loffset + i * blksize,
 204                                     FINDBLK_TEST) == NULL) {
 205                                 break;
 206                         }
 207                         ++i;
 208                 }
 209
 210                 /*
 211                  * We got everything or everything is in the cache, no
 212                  * point continuing.
 213                  */
 214                 if (i >= maxra)
 215                         return 0;
 216                 maxra -= i;
 217                 loffset += i * blksize;
 218                 reqbp = bp = NULL;
 219         } else {
 220                 __debugvar off_t firstread = bp->b_loffset;
 221                 int nblks;
 222
 223                 /*
 224                  * Set-up synchronous read for bp.
 225                  */
 226                 bp->b_cmd = BUF_CMD_READ;
 227                 bp->b_bio1.bio_done = biodone_sync;
 228                 bp->b_bio1.bio_flags |= BIO_SYNC;
 229
 230                 KASSERT(firstread != NOOFFSET,
 231                         ("cluster_read: no buffer offset"));
 232
 233                 /*
 234                  * nblks is our cluster_rbuild request size, limited
 235                  * primarily by the device.
 236                  */
 237                 if ((nblks = maxra) > maxrbuild)
 238                         nblks = maxrbuild;
 239
 240                 if (nblks > 1) {
 241                         int burstbytes;
 242
 243                         error = VOP_BMAP(vp, loffset, &doffset,
 244                                          &burstbytes, NULL, BUF_CMD_READ);
 245                         if (error)
 246                                 goto single_block_read;
 247                         if (nblks > burstbytes / blksize)
 248                                 nblks = burstbytes / blksize;
 249                         if (doffset == NOOFFSET)
 250                                 goto single_block_read;
 251                         if (nblks <= 1)
 252                                 goto single_block_read;
 253
 254                         bp = cluster_rbuild(vp, filesize, loffset,
 255                                             doffset, blksize, nblks, bp);
 256                         loffset += bp->b_bufsize;
 257                         maxra -= bp->b_bufsize / blksize;
 258                 } else {
 259 single_block_read:
 260                         /*
 261                          * If it isn't in the cache, then get a chunk from
 262                          * disk if sequential, otherwise just get the block.
 263                          */
 264                         cluster_setram(bp);
 265                         loffset += blksize;
 266                         --maxra;
 267                 }
 268         }
 269
 270         /*
 271          * If B_CACHE was not set issue bp.  bp will either be an
 272          * asynchronous cluster buf or a synchronous single-buf.
 273          * If it is a single buf it will be the same as reqbp.
 274          *
 275          * NOTE: Once an async cluster buf is issued bp becomes invalid.
 276          */
 277         if (bp) {
 278 #if defined(CLUSTERDEBUG)
 279                 if (rcluster)
 280                         kprintf("S(%012jx,%d,%d)\n",
 281                             (intmax_t)bp->b_loffset, bp->b_bcount, maxra);
 282 #endif
 283                 if ((bp->b_flags & B_CLUSTER) == 0)
 284                         vfs_busy_pages(vp, bp);
 285                 bp->b_flags &= ~(B_ERROR|B_INVAL);
 286                 vn_strategy(vp, &bp->b_bio1);
 287                 error = 0;
 288                 /* bp invalid now */
 289         }
 290
 291         /*
 292          * If we have been doing sequential I/O, then do some read-ahead.
 293          * The code above us should have positioned us at the next likely
 294          * offset.
 295          *
 296          * Only mess with buffers which we can immediately lock.  HAMMER
 297          * will do device-readahead irrespective of what the blocks
 298          * represent.
 299          */
 300         while (error == 0 && maxra > 0) {
 301                 int burstbytes;
 302                 int tmp_error;
 303                 int nblks;
 304
 305                 rbp = getblk(vp, loffset, blksize,
 306                              GETBLK_SZMATCH|GETBLK_NOWAIT, 0);
 307                 if (rbp == NULL)
 308                         goto no_read_ahead;
 309                 if ((rbp->b_flags & B_CACHE)) {
 310                         bqrelse(rbp);
 311                         goto no_read_ahead;
 312                 }
 313
 314                 /*
 315                  * An error from the read-ahead bmap has nothing to do
 316                  * with the caller's original request.
 317                  */
 318                 tmp_error = VOP_BMAP(vp, loffset, &doffset,
 319                                      &burstbytes, NULL, BUF_CMD_READ);
 320                 if (tmp_error || doffset == NOOFFSET) {
 321                         rbp->b_flags |= B_INVAL;
 322                         brelse(rbp);
 323                         rbp = NULL;
 324                         goto no_read_ahead;
 325                 }
 326                 if ((nblks = maxra) > maxrbuild)
 327                         nblks = maxrbuild;
 328                 if (nblks > burstbytes / blksize)
 329                         nblks = burstbytes / blksize;
 330
 331                 /*
 332                  * rbp: async read
 333                  */
 334                 rbp->b_cmd = BUF_CMD_READ;
 335                 /*rbp->b_flags |= B_AGE*/;
 336                 cluster_setram(rbp);
 337
 338                 if (nblks > 1) {
 339                         rbp = cluster_rbuild(vp, filesize, loffset,
 340                                              doffset, blksize,
 341                                              nblks, rbp);
 342                 } else {
 343                         rbp->b_bio2.bio_offset = doffset;
 344                 }
 345
 346 #if defined(CLUSTERDEBUG)
 347                 if (rcluster) {
 348                         if (bp) {
 349                                 kprintf("A+(%012jx,%d,%jd) "
 350                                         "doff=%012jx minr=%zd ra=%d\n",
 351                                     (intmax_t)loffset, rbp->b_bcount,
 352                                     (intmax_t)(loffset - origoffset),
 353                                     (intmax_t)doffset, minreq, maxra);
 354                         } else {
 355                                 kprintf("A-(%012jx,%d,%jd) "
 356                                         "doff=%012jx minr=%zd ra=%d\n",
 357                                     (intmax_t)rbp->b_loffset, rbp->b_bcount,
 358                                     (intmax_t)(loffset - origoffset),
 359                                     (intmax_t)doffset, minreq, maxra);
 360                         }
 361                 }
 362 #endif
 363                 rbp->b_flags &= ~(B_ERROR|B_INVAL);
 364
 365                 if ((rbp->b_flags & B_CLUSTER) == 0)
 366                         vfs_busy_pages(vp, rbp);
 367                 BUF_KERNPROC(rbp);
 368                 loffset += rbp->b_bufsize;
 369                 maxra -= rbp->b_bufsize / blksize;
 370                 vn_strategy(vp, &rbp->b_bio1);
 371                 /* rbp invalid now */
 372         }
 373
 374         /*
 375          * Wait for our original buffer to complete its I/O.  reqbp will
 376          * be NULL if the original buffer was B_CACHE.  We are returning
 377          * (*bpp) which is the same as reqbp when reqbp != NULL.
 378          */
 379 no_read_ahead:
 380         if (reqbp) {
 381                 KKASSERT(reqbp->b_bio1.bio_flags & BIO_SYNC);
 382                 error = biowait(&reqbp->b_bio1, "clurd");
 383         }
 384         return (error);
 385 }
 386
 387 /*
 388  * If blocks are contiguous on disk, use this to provide clustered
 389  * read ahead.  We will read as many blocks as possible sequentially
 390  * and then parcel them up into logical blocks in the buffer hash table.
 391  *
 392  * This function either returns a cluster buf or it returns fbp.  fbp is
 393  * already expected to be set up as a synchronous or asynchronous request.
 394  *
 395  * If a cluster buf is returned it will always be async.
 396  */
 397 static struct buf *
 398 cluster_rbuild(struct vnode *vp, off_t filesize, off_t loffset, off_t doffset,
 399                int blksize, int run, struct buf *fbp)
 400 {
 401         struct buf *bp, *tbp;
 402         off_t boffset;
 403         int i, j;
 404         int maxiosize = vmaxiosize(vp);
 405
 406         /*
 407          * avoid a division
 408          */
 409         while (loffset + run * blksize > filesize) {
 410                 --run;
 411         }
 412
 413         tbp = fbp;
 414         tbp->b_bio2.bio_offset = doffset;
 415         if((tbp->b_flags & B_MALLOC) ||
 416             ((tbp->b_flags & B_VMIO) == 0) || (run <= 1)) {
 417                 return tbp;
 418         }
 419
 420         bp = trypbuf_kva(&cluster_pbuf_freecnt);
 421         if (bp == NULL) {
 422                 return tbp;
 423         }
 424
 425         /*
 426          * We are synthesizing a buffer out of vm_page_t's, but
 427          * if the block size is not page aligned then the starting
 428          * address may not be either.  Inherit the b_data offset
 429          * from the original buffer.
 430          */
 431         bp->b_data = (char *)((vm_offset_t)bp->b_data |
 432             ((vm_offset_t)tbp->b_data & PAGE_MASK));
 433         bp->b_flags |= B_CLUSTER | B_VMIO;
 434         bp->b_cmd = BUF_CMD_READ;
 435         bp->b_bio1.bio_done = cluster_callback;         /* default to async */
 436         bp->b_bio1.bio_caller_info1.cluster_head = NULL;
 437         bp->b_bio1.bio_caller_info2.cluster_tail = NULL;
 438         bp->b_loffset = loffset;
 439         bp->b_bio2.bio_offset = doffset;
 440         KASSERT(bp->b_loffset != NOOFFSET,
 441                 ("cluster_rbuild: no buffer offset"));
 442
 443         bp->b_bcount = 0;
 444         bp->b_bufsize = 0;
 445         bp->b_xio.xio_npages = 0;
 446
 447         for (boffset = doffset, i = 0; i < run; ++i, boffset += blksize) {
 448                 if (i) {
 449                         if ((bp->b_xio.xio_npages * PAGE_SIZE) +
 450                             round_page(blksize) > maxiosize) {
 451                                 break;
 452                         }
 453
 454                         /*
 455                          * Shortcut some checks and try to avoid buffers that
 456                          * would block in the lock.  The same checks have to
 457                          * be made again after we officially get the buffer.
 458                          */
 459                         tbp = getblk(vp, loffset + i * blksize, blksize,
 460                                      GETBLK_SZMATCH|GETBLK_NOWAIT, 0);
 461                         if (tbp == NULL)
 462                                 break;
 463                         for (j = 0; j < tbp->b_xio.xio_npages; j++) {
 464                                 if (tbp->b_xio.xio_pages[j]->valid)
 465                                         break;
 466                         }
 467                         if (j != tbp->b_xio.xio_npages) {
 468                                 bqrelse(tbp);
 469                                 break;
 470                         }
 471
 472                         /*
 473                          * Stop scanning if the buffer is fuly valid
 474                          * (marked B_CACHE), or locked (may be doing a
 475                          * background write), or if the buffer is not
 476                          * VMIO backed.  The clustering code can only deal
 477                          * with VMIO-backed buffers.
 478                          */
 479                         if ((tbp->b_flags & (B_CACHE|B_LOCKED)) ||
 480                             (tbp->b_flags & B_VMIO) == 0 ||
 481                             (LIST_FIRST(&tbp->b_dep) != NULL &&
 482                              buf_checkread(tbp))
 483                         ) {
 484                                 bqrelse(tbp);
 485                                 break;
 486                         }
 487
 488                         /*
 489                          * The buffer must be completely invalid in order to
 490                          * take part in the cluster.  If it is partially valid
 491                          * then we stop.
 492                          */
 493                         for (j = 0;j < tbp->b_xio.xio_npages; j++) {
 494                                 if (tbp->b_xio.xio_pages[j]->valid)
 495                                         break;
 496                         }
 497                         if (j != tbp->b_xio.xio_npages) {
 498                                 bqrelse(tbp);
 499                                 break;
 500                         }
 501
 502                         /*
 503                          * Set a read-ahead mark as appropriate
 504                          */
 505                         if (i == 1 || i == (run - 1))
 506                                 cluster_setram(tbp);
 507
 508                         /*
 509                          * Depress the priority of buffers not explicitly
 510                          * requested.
 511                          */
 512                         /* tbp->b_flags |= B_AGE; */
 513
 514                         /*
 515                          * Set the block number if it isn't set, otherwise
 516                          * if it is make sure it matches the block number we
 517                          * expect.
 518                          */
 519                         if (tbp->b_bio2.bio_offset == NOOFFSET) {
 520                                 tbp->b_bio2.bio_offset = boffset;
 521                         } else if (tbp->b_bio2.bio_offset != boffset) {
 522                                 brelse(tbp);
 523                                 break;
 524                         }
 525                 }
 526
 527                 /*
 528                  * The passed-in tbp (i == 0) will already be set up for
 529                  * async or sync operation.  All other tbp's acquire in
 530                  * our loop are set up for async operation.
 531                  */
 532                 tbp->b_cmd = BUF_CMD_READ;
 533                 BUF_KERNPROC(tbp);
 534                 cluster_append(&bp->b_bio1, tbp);
 535                 for (j = 0; j < tbp->b_xio.xio_npages; ++j) {
 536                         vm_page_t m;
 537                         m = tbp->b_xio.xio_pages[j];
 538                         vm_page_io_start(m);
 539                         vm_object_pip_add(m->object, 1);
 540                         if ((bp->b_xio.xio_npages == 0) ||
 541                                 (bp->b_xio.xio_pages[bp->b_xio.xio_npages-1] != m)) {
 542                                 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m;
 543                                 bp->b_xio.xio_npages++;
 544                         }
 545                         if ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL)
 546                                 tbp->b_xio.xio_pages[j] = bogus_page;
 547                 }
 548                 /*
 549                  * XXX shouldn't this be += size for both, like in
 550                  * cluster_wbuild()?
 551                  *
 552                  * Don't inherit tbp->b_bufsize as it may be larger due to
 553                  * a non-page-aligned size.  Instead just aggregate using
 554                  * 'size'.
 555                  */
 556                 if (tbp->b_bcount != blksize)
 557                     kprintf("warning: tbp->b_bcount wrong %d vs %d\n", tbp->b_bcount, blksize);
 558                 if (tbp->b_bufsize != blksize)
 559                     kprintf("warning: tbp->b_bufsize wrong %d vs %d\n", tbp->b_bufsize, blksize);
 560                 bp->b_bcount += blksize;
 561                 bp->b_bufsize += blksize;
 562         }
 563
 564         /*
 565          * Fully valid pages in the cluster are already good and do not need
 566          * to be re-read from disk.  Replace the page with bogus_page
 567          */
 568         for (j = 0; j < bp->b_xio.xio_npages; j++) {
 569                 if ((bp->b_xio.xio_pages[j]->valid & VM_PAGE_BITS_ALL) ==
 570                     VM_PAGE_BITS_ALL) {
 571                         bp->b_xio.xio_pages[j] = bogus_page;
 572                 }
 573         }
 574         if (bp->b_bufsize > bp->b_kvasize) {
 575                 panic("cluster_rbuild: b_bufsize(%d) > b_kvasize(%d)",
 576                     bp->b_bufsize, bp->b_kvasize);
 577         }
 578         pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
 579                 (vm_page_t *)bp->b_xio.xio_pages, bp->b_xio.xio_npages);
 580         BUF_KERNPROC(bp);
 581         return (bp);
 582 }
 583
 584 /*
 585  * Cleanup after a clustered read or write.
 586  * This is complicated by the fact that any of the buffers might have
 587  * extra memory (if there were no empty buffer headers at allocbuf time)
 588  * that we will need to shift around.
 589  *
 590  * The returned bio is &bp->b_bio1
 591  */
 592 void
 593 cluster_callback(struct bio *bio)
 594 {
 595         struct buf *bp = bio->bio_buf;
 596         struct buf *tbp;
 597         int error = 0;
 598
 599         /*
 600          * Must propogate errors to all the components.  A short read (EOF)
 601          * is a critical error.
 602          */
 603         if (bp->b_flags & B_ERROR) {
 604                 error = bp->b_error;
 605         } else if (bp->b_bcount != bp->b_bufsize) {
 606                 panic("cluster_callback: unexpected EOF on cluster %p!", bio);
 607         }
 608
 609         pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_xio.xio_npages);
 610         /*
 611          * Move memory from the large cluster buffer into the component
 612          * buffers and mark IO as done on these.  Since the memory map
 613          * is the same, no actual copying is required.
 614          */
 615         while ((tbp = bio->bio_caller_info1.cluster_head) != NULL) {
 616                 bio->bio_caller_info1.cluster_head = tbp->b_cluster_next;
 617                 if (error) {
 618                         tbp->b_flags |= B_ERROR | B_IODEBUG;
 619                         tbp->b_error = error;
 620                 } else {
 621                         tbp->b_dirtyoff = tbp->b_dirtyend = 0;
 622                         tbp->b_flags &= ~(B_ERROR|B_INVAL);
 623                         tbp->b_flags |= B_IODEBUG;
 624                         /*
 625                          * XXX the bdwrite()/bqrelse() issued during
 626                          * cluster building clears B_RELBUF (see bqrelse()
 627                          * comment).  If direct I/O was specified, we have
 628                          * to restore it here to allow the buffer and VM
 629                          * to be freed.
 630                          */
 631                         if (tbp->b_flags & B_DIRECT)
 632                                 tbp->b_flags |= B_RELBUF;
 633                 }
 634                 biodone(&tbp->b_bio1);
 635         }
 636         relpbuf(bp, &cluster_pbuf_freecnt);
 637 }
 638
 639 /*
 640  *      cluster_wbuild_wb:
 641  *
 642  *      Implement modified write build for cluster.
 643  *
 644  *              write_behind = 0        write behind disabled
 645  *              write_behind = 1        write behind normal (default)
 646  *              write_behind = 2        write behind backed-off
 647  */
 648
 649 static __inline int
 650 cluster_wbuild_wb(struct vnode *vp, int blksize, off_t start_loffset, int len)
 651 {
 652         int r = 0;
 653
 654         switch(write_behind) {
 655         case 2:
 656                 if (start_loffset < len)
 657                         break;
 658                 start_loffset -= len;
 659                 /* fall through */
 660         case 1:
 661                 r = cluster_wbuild(vp, blksize, start_loffset, len);
 662                 /* fall through */
 663         default:
 664                 /* fall through */
 665                 break;
 666         }
 667         return(r);
 668 }
 669
 670 /*
 671  * Do clustered write for FFS.
 672  *
 673  * Three cases:
 674  *      1. Write is not sequential (write asynchronously)
 675  *      Write is sequential:
 676  *      2.      beginning of cluster - begin cluster
 677  *      3.      middle of a cluster - add to cluster
 678  *      4.      end of a cluster - asynchronously write cluster
 679  */
 680 void
 681 cluster_write(struct buf *bp, off_t filesize, int blksize, int seqcount)
 682 {
 683         struct vnode *vp;
 684         off_t loffset;
 685         int maxclen, cursize;
 686         int async;
 687
 688         vp = bp->b_vp;
 689         if (vp->v_type == VREG)
 690                 async = vp->v_mount->mnt_flag & MNT_ASYNC;
 691         else
 692                 async = 0;
 693         loffset = bp->b_loffset;
 694         KASSERT(bp->b_loffset != NOOFFSET,
 695                 ("cluster_write: no buffer offset"));
 696
 697         /* Initialize vnode to beginning of file. */
 698         if (loffset == 0)
 699                 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0;
 700
 701         if (vp->v_clen == 0 || loffset != vp->v_lastw + blksize ||
 702             bp->b_bio2.bio_offset == NOOFFSET ||
 703             (bp->b_bio2.bio_offset != vp->v_lasta + blksize)) {
 704                 maxclen = vmaxiosize(vp);
 705                 if (vp->v_clen != 0) {
 706                         /*
 707                          * Next block is not sequential.
 708                          *
 709                          * If we are not writing at end of file, the process
 710                          * seeked to another point in the file since its last
 711                          * write, or we have reached our maximum cluster size,
 712                          * then push the previous cluster. Otherwise try
 713                          * reallocating to make it sequential.
 714                          *
 715                          * Change to algorithm: only push previous cluster if
 716                          * it was sequential from the point of view of the
 717                          * seqcount heuristic, otherwise leave the buffer
 718                          * intact so we can potentially optimize the I/O
 719                          * later on in the buf_daemon or update daemon
 720                          * flush.
 721                          */
 722                         cursize = vp->v_lastw - vp->v_cstart + blksize;
 723                         if (bp->b_loffset + blksize != filesize ||
 724                             loffset != vp->v_lastw + blksize || vp->v_clen <= cursize) {
 725                                 if (!async && seqcount > 0) {
 726                                         cluster_wbuild_wb(vp, blksize,
 727                                                 vp->v_cstart, cursize);
 728                                 }
 729                         } else {
 730                                 struct buf **bpp, **endbp;
 731                                 struct cluster_save *buflist;
 732
 733                                 buflist = cluster_collectbufs(vp, bp, blksize);
 734                                 endbp = &buflist->bs_children
 735                                     [buflist->bs_nchildren - 1];
 736                                 if (VOP_REALLOCBLKS(vp, buflist)) {
 737                                         /*
 738                                          * Failed, push the previous cluster
 739                                          * if *really* writing sequentially
 740                                          * in the logical file (seqcount > 1),
 741                                          * otherwise delay it in the hopes that
 742                                          * the low level disk driver can
 743                                          * optimize the write ordering.
 744                                          */
 745                                         for (bpp = buflist->bs_children;
 746                                              bpp < endbp; bpp++)
 747                                                 brelse(*bpp);
 748                                         kfree(buflist, M_SEGMENT);
 749                                         if (seqcount > 1) {
 750                                                 cluster_wbuild_wb(vp,
 751                                                     blksize, vp->v_cstart,
 752                                                     cursize);
 753                                         }
 754                                 } else {
 755                                         /*
 756                                          * Succeeded, keep building cluster.
 757                                          */
 758                                         for (bpp = buflist->bs_children;
 759                                              bpp <= endbp; bpp++)
 760                                                 bdwrite(*bpp);
 761                                         kfree(buflist, M_SEGMENT);
 762                                         vp->v_lastw = loffset;
 763                                         vp->v_lasta = bp->b_bio2.bio_offset;
 764                                         return;
 765                                 }
 766                         }
 767                 }
 768                 /*
 769                  * Consider beginning a cluster. If at end of file, make
 770                  * cluster as large as possible, otherwise find size of
 771                  * existing cluster.
 772                  */
 773                 if ((vp->v_type == VREG) &&
 774                     bp->b_loffset + blksize != filesize &&
 775                     (bp->b_bio2.bio_offset == NOOFFSET) &&
 776                     (VOP_BMAP(vp, loffset, &bp->b_bio2.bio_offset, &maxclen, NULL, BUF_CMD_WRITE) ||
 777                      bp->b_bio2.bio_offset == NOOFFSET)) {
 778                         bawrite(bp);
 779                         vp->v_clen = 0;
 780                         vp->v_lasta = bp->b_bio2.bio_offset;
 781                         vp->v_cstart = loffset + blksize;
 782                         vp->v_lastw = loffset;
 783                         return;
 784                 }
 785                 if (maxclen > blksize)
 786                         vp->v_clen = maxclen - blksize;
 787                 else
 788                         vp->v_clen = 0;
 789                 if (!async && vp->v_clen == 0) { /* I/O not contiguous */
 790                         vp->v_cstart = loffset + blksize;
 791                         bawrite(bp);
 792                 } else {        /* Wait for rest of cluster */
 793                         vp->v_cstart = loffset;
 794                         bdwrite(bp);
 795                 }
 796         } else if (loffset == vp->v_cstart + vp->v_clen) {
 797                 /*
 798                  * At end of cluster, write it out if seqcount tells us we
 799                  * are operating sequentially, otherwise let the buf or
 800                  * update daemon handle it.
 801                  */
 802                 bdwrite(bp);
 803                 if (seqcount > 1)
 804                         cluster_wbuild_wb(vp, blksize, vp->v_cstart,
 805                                           vp->v_clen + blksize);
 806                 vp->v_clen = 0;
 807                 vp->v_cstart = loffset + blksize;
 808         } else if (vm_page_count_severe()) {
 809                 /*
 810                  * We are low on memory, get it going NOW
 811                  */
 812                 bawrite(bp);
 813         } else {
 814                 /*
 815                  * In the middle of a cluster, so just delay the I/O for now.
 816                  */
 817                 bdwrite(bp);
 818         }
 819         vp->v_lastw = loffset;
 820         vp->v_lasta = bp->b_bio2.bio_offset;
 821 }
 822
 823
 824 /*
 825  * This is an awful lot like cluster_rbuild...wish they could be combined.
 826  * The last lbn argument is the current block on which I/O is being
 827  * performed.  Check to see that it doesn't fall in the middle of
 828  * the current block (if last_bp == NULL).
 829  */
 830 int
 831 cluster_wbuild(struct vnode *vp, int blksize, off_t start_loffset, int bytes)
 832 {
 833         struct buf *bp, *tbp;
 834         int i, j;
 835         int totalwritten = 0;
 836         int maxiosize = vmaxiosize(vp);
 837
 838         while (bytes > 0) {
 839                 /*
 840                  * If the buffer is not delayed-write (i.e. dirty), or it
 841                  * is delayed-write but either locked or inval, it cannot
 842                  * partake in the clustered write.
 843                  */
 844                 tbp = findblk(vp, start_loffset, FINDBLK_NBLOCK);
 845                 if (tbp == NULL ||
 846                     (tbp->b_flags & (B_LOCKED | B_INVAL | B_DELWRI)) != B_DELWRI ||
 847                     (LIST_FIRST(&tbp->b_dep) && buf_checkwrite(tbp))) {
 848                         if (tbp)
 849                                 BUF_UNLOCK(tbp);
 850                         start_loffset += blksize;
 851                         bytes -= blksize;
 852                         continue;
 853                 }
 854                 bremfree(tbp);
 855                 KKASSERT(tbp->b_cmd == BUF_CMD_DONE);
 856
 857                 /*
 858                  * Extra memory in the buffer, punt on this buffer.
 859                  * XXX we could handle this in most cases, but we would
 860                  * have to push the extra memory down to after our max
 861                  * possible cluster size and then potentially pull it back
 862                  * up if the cluster was terminated prematurely--too much
 863                  * hassle.
 864                  */
 865                 if (((tbp->b_flags & (B_CLUSTEROK|B_MALLOC)) != B_CLUSTEROK) ||
 866                     (tbp->b_bcount != tbp->b_bufsize) ||
 867                     (tbp->b_bcount != blksize) ||
 868                     (bytes == blksize) ||
 869                     ((bp = getpbuf_kva(&cluster_pbuf_freecnt)) == NULL)) {
 870                         totalwritten += tbp->b_bufsize;
 871                         bawrite(tbp);
 872                         start_loffset += blksize;
 873                         bytes -= blksize;
 874                         continue;
 875                 }
 876
 877                 /*
 878                  * Set up the pbuf.  Track our append point with b_bcount
 879                  * and b_bufsize.  b_bufsize is not used by the device but
 880                  * our caller uses it to loop clusters and we use it to
 881                  * detect a premature EOF on the block device.
 882                  */
 883                 bp->b_bcount = 0;
 884                 bp->b_bufsize = 0;
 885                 bp->b_xio.xio_npages = 0;
 886                 bp->b_loffset = tbp->b_loffset;
 887                 bp->b_bio2.bio_offset = tbp->b_bio2.bio_offset;
 888
 889                 /*
 890                  * We are synthesizing a buffer out of vm_page_t's, but
 891                  * if the block size is not page aligned then the starting
 892                  * address may not be either.  Inherit the b_data offset
 893                  * from the original buffer.
 894                  */
 895                 bp->b_data = (char *)((vm_offset_t)bp->b_data |
 896                     ((vm_offset_t)tbp->b_data & PAGE_MASK));
 897                 bp->b_flags &= ~B_ERROR;
 898                 bp->b_flags |= B_CLUSTER | B_BNOCLIP |
 899                         (tbp->b_flags & (B_VMIO | B_NEEDCOMMIT));
 900                 bp->b_bio1.bio_caller_info1.cluster_head = NULL;
 901                 bp->b_bio1.bio_caller_info2.cluster_tail = NULL;
 902
 903                 /*
 904                  * From this location in the file, scan forward to see
 905                  * if there are buffers with adjacent data that need to
 906                  * be written as well.
 907                  */
 908                 for (i = 0; i < bytes; (i += blksize), (start_loffset += blksize)) {
 909                         if (i != 0) { /* If not the first buffer */
 910                                 tbp = findblk(vp, start_loffset,
 911                                               FINDBLK_NBLOCK);
 912                                 /*
 913                                  * Buffer not found or could not be locked
 914                                  * non-blocking.
 915                                  */
 916                                 if (tbp == NULL)
 917                                         break;
 918
 919                                 /*
 920                                  * If it IS in core, but has different
 921                                  * characteristics, then don't cluster
 922                                  * with it.
 923                                  */
 924                                 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK |
 925                                      B_INVAL | B_DELWRI | B_NEEDCOMMIT))
 926                                     != (B_DELWRI | B_CLUSTEROK |
 927                                      (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) ||
 928                                     (tbp->b_flags & B_LOCKED) ||
 929                                     (LIST_FIRST(&tbp->b_dep) &&
 930                                      buf_checkwrite(tbp))
 931                                 ) {
 932                                         BUF_UNLOCK(tbp);
 933                                         break;
 934                                 }
 935
 936                                 /*
 937                                  * Check that the combined cluster
 938                                  * would make sense with regard to pages
 939                                  * and would not be too large
 940                                  */
 941                                 if ((tbp->b_bcount != blksize) ||
 942                                   ((bp->b_bio2.bio_offset + i) !=
 943                                     tbp->b_bio2.bio_offset) ||
 944                                   ((tbp->b_xio.xio_npages + bp->b_xio.xio_npages) >
 945                                     (maxiosize / PAGE_SIZE))) {
 946                                         BUF_UNLOCK(tbp);
 947                                         break;
 948                                 }
 949                                 /*
 950                                  * Ok, it's passed all the tests,
 951                                  * so remove it from the free list
 952                                  * and mark it busy. We will use it.
 953                                  */
 954                                 bremfree(tbp);
 955                                 KKASSERT(tbp->b_cmd == BUF_CMD_DONE);
 956                         } /* end of code for non-first buffers only */
 957
 958                         /*
 959                          * If the IO is via the VM then we do some
 960                          * special VM hackery (yuck).  Since the buffer's
 961                          * block size may not be page-aligned it is possible
 962                          * for a page to be shared between two buffers.  We
 963                          * have to get rid of the duplication when building
 964                          * the cluster.
 965                          */
 966                         if (tbp->b_flags & B_VMIO) {
 967                                 vm_page_t m;
 968
 969                                 if (i != 0) { /* if not first buffer */
 970                                         for (j = 0; j < tbp->b_xio.xio_npages; ++j) {
 971                                                 m = tbp->b_xio.xio_pages[j];
 972                                                 if (m->flags & PG_BUSY) {
 973                                                         bqrelse(tbp);
 974                                                         goto finishcluster;
 975                                                 }
 976                                         }
 977                                 }
 978
 979                                 for (j = 0; j < tbp->b_xio.xio_npages; ++j) {
 980                                         m = tbp->b_xio.xio_pages[j];
 981                                         vm_page_io_start(m);
 982                                         vm_object_pip_add(m->object, 1);
 983                                         if ((bp->b_xio.xio_npages == 0) ||
 984                                           (bp->b_xio.xio_pages[bp->b_xio.xio_npages - 1] != m)) {
 985                                                 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m;
 986                                                 bp->b_xio.xio_npages++;
 987                                         }
 988                                 }
 989                         }
 990                         bp->b_bcount += blksize;
 991                         bp->b_bufsize += blksize;
 992
 993                         bundirty(tbp);
 994                         tbp->b_flags &= ~B_ERROR;
 995                         tbp->b_cmd = BUF_CMD_WRITE;
 996                         BUF_KERNPROC(tbp);
 997                         cluster_append(&bp->b_bio1, tbp);
 998
 999                         /*
1000                          * check for latent dependencies to be handled
1001                          */
1002                         if (LIST_FIRST(&tbp->b_dep) != NULL)
1003                                 buf_start(tbp);
1004                 }
1005         finishcluster:
1006                 pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
1007                         (vm_page_t *) bp->b_xio.xio_pages, bp->b_xio.xio_npages);
1008                 if (bp->b_bufsize > bp->b_kvasize) {
1009                         panic(
1010                             "cluster_wbuild: b_bufsize(%d) > b_kvasize(%d)\n",
1011                             bp->b_bufsize, bp->b_kvasize);
1012                 }
1013                 totalwritten += bp->b_bufsize;
1014                 bp->b_dirtyoff = 0;
1015                 bp->b_dirtyend = bp->b_bufsize;
1016                 bp->b_bio1.bio_done = cluster_callback;
1017                 bp->b_cmd = BUF_CMD_WRITE;
1018
1019                 vfs_busy_pages(vp, bp);
1020                 bsetrunningbufspace(bp, bp->b_bufsize);
1021                 BUF_KERNPROC(bp);
1022                 vn_strategy(vp, &bp->b_bio1);
1023
1024                 bytes -= i;
1025         }
1026         return totalwritten;
1027 }
1028
1029 /*
1030  * Collect together all the buffers in a cluster.
1031  * Plus add one additional buffer.
1032  */
1033 static struct cluster_save *
1034 cluster_collectbufs(struct vnode *vp, struct buf *last_bp, int blksize)
1035 {
1036         struct cluster_save *buflist;
1037         struct buf *bp;
1038         off_t loffset;
1039         int i, len;
1040
1041         len = (int)(vp->v_lastw - vp->v_cstart + blksize) / blksize;
1042         buflist = kmalloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist),
1043                          M_SEGMENT, M_WAITOK);
1044         buflist->bs_nchildren = 0;
1045         buflist->bs_children = (struct buf **) (buflist + 1);
1046         for (loffset = vp->v_cstart, i = 0; i < len; (loffset += blksize), i++) {
1047                 (void) bread(vp, loffset, last_bp->b_bcount, &bp);
1048                 buflist->bs_children[i] = bp;
1049                 if (bp->b_bio2.bio_offset == NOOFFSET) {
1050                         VOP_BMAP(bp->b_vp, bp->b_loffset,
1051                                  &bp->b_bio2.bio_offset,
1052                                  NULL, NULL, BUF_CMD_WRITE);
1053                 }
1054         }
1055         buflist->bs_children[i] = bp = last_bp;
1056         if (bp->b_bio2.bio_offset == NOOFFSET) {
1057                 VOP_BMAP(bp->b_vp, bp->b_loffset, &bp->b_bio2.bio_offset,
1058                          NULL, NULL, BUF_CMD_WRITE);
1059         }
1060         buflist->bs_nchildren = i + 1;
1061         return (buflist);
1062 }
1063
1064 void
1065 cluster_append(struct bio *bio, struct buf *tbp)
1066 {
1067         tbp->b_cluster_next = NULL;
1068         if (bio->bio_caller_info1.cluster_head == NULL) {
1069                 bio->bio_caller_info1.cluster_head = tbp;
1070                 bio->bio_caller_info2.cluster_tail = tbp;
1071         } else {
1072                 bio->bio_caller_info2.cluster_tail->b_cluster_next = tbp;
1073                 bio->bio_caller_info2.cluster_tail = tbp;
1074         }
1075 }
1076
1077 static
1078 void
1079 cluster_setram (struct buf *bp)
1080 {
1081         bp->b_flags |= B_RAM;
1082         if (bp->b_xio.xio_npages)
1083                 vm_page_flag_set(bp->b_xio.xio_pages[0], PG_RAM);
1084 }