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 1.21 2006/04/28 16:34:01 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 #if defined(CLUSTERDEBUG)
  60 #include <sys/sysctl.h>
  61 static int      rcluster= 0;
  62 SYSCTL_INT(_debug, OID_AUTO, rcluster, CTLFLAG_RW, &rcluster, 0, "");
  63 #endif
  64
  65 static MALLOC_DEFINE(M_SEGMENT, "cluster_save", "cluster_save buffer");
  66
  67 static struct cluster_save *
  68         cluster_collectbufs (struct vnode *vp, struct buf *last_bp,
  69                             int lblocksize);
  70 static struct buf *
  71         cluster_rbuild (struct vnode *vp, off_t filesize, off_t loffset,
  72                             off_t doffset, int size, int run, struct buf *fbp);
  73 static void cluster_callback (struct bio *);
  74
  75
  76 static int write_behind = 1;
  77 SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0, "");
  78
  79 extern vm_page_t        bogus_page;
  80
  81 extern int cluster_pbuf_freecnt;
  82
  83 /*
  84  * Maximum number of blocks for read-ahead.
  85  */
  86 #define MAXRA 32
  87
  88 /*
  89  * This replaces bread.
  90  */
  91 int
  92 cluster_read(struct vnode *vp, off_t filesize, off_t loffset,
  93              int size, int totread, int seqcount, struct buf **bpp)
  94 {
  95         struct buf *bp, *rbp, *reqbp;
  96         off_t origoffset;
  97         off_t doffset;
  98         int error;
  99         int i;
 100         int maxra, racluster;
 101
 102         error = 0;
 103
 104         /*
 105          * Try to limit the amount of read-ahead by a few
 106          * ad-hoc parameters.  This needs work!!!
 107          */
 108         racluster = vp->v_mount->mnt_iosize_max / size;
 109         maxra = 2 * racluster + (totread / size);
 110         if (maxra > MAXRA)
 111                 maxra = MAXRA;
 112         if (maxra > nbuf/8)
 113                 maxra = nbuf/8;
 114
 115         /*
 116          * get the requested block
 117          */
 118         *bpp = reqbp = bp = getblk(vp, loffset, size, 0, 0);
 119         origoffset = loffset;
 120
 121         /*
 122          * if it is in the cache, then check to see if the reads have been
 123          * sequential.  If they have, then try some read-ahead, otherwise
 124          * back-off on prospective read-aheads.
 125          */
 126         if (bp->b_flags & B_CACHE) {
 127                 if (!seqcount) {
 128                         return 0;
 129                 } else if ((bp->b_flags & B_RAM) == 0) {
 130                         return 0;
 131                 } else {
 132                         struct buf *tbp;
 133                         bp->b_flags &= ~B_RAM;
 134                         /*
 135                          * We do the crit here so that there is no window
 136                          * between the findblk and the b_usecount increment
 137                          * below.  We opt to keep the crit out of the loop
 138                          * for efficiency.
 139                          */
 140                         crit_enter();
 141                         for (i = 1; i < maxra; i++) {
 142                                 if (!(tbp = findblk(vp, loffset + i * size))) {
 143                                         break;
 144                                 }
 145
 146                                 /*
 147                                  * Set another read-ahead mark so we know
 148                                  * to check again.
 149                                  */
 150                                 if (((i % racluster) == (racluster - 1)) ||
 151                                         (i == (maxra - 1)))
 152                                         tbp->b_flags |= B_RAM;
 153                         }
 154                         crit_exit();
 155                         if (i >= maxra) {
 156                                 return 0;
 157                         }
 158                         loffset += i * size;
 159                 }
 160                 reqbp = bp = NULL;
 161         } else {
 162                 off_t firstread = bp->b_loffset;
 163                 int nblks;
 164
 165                 KASSERT(firstread != NOOFFSET,
 166                         ("cluster_read: no buffer offset"));
 167                 if (firstread + totread > filesize)
 168                         totread = (int)(filesize - firstread);
 169                 nblks = totread / size;
 170                 if (nblks) {
 171                         int burstbytes;
 172
 173                         if (nblks > racluster)
 174                                 nblks = racluster;
 175
 176                         error = VOP_BMAP(vp, loffset, NULL,
 177                                          &doffset, &burstbytes, NULL);
 178                         if (error)
 179                                 goto single_block_read;
 180                         if (doffset == NOOFFSET)
 181                                 goto single_block_read;
 182                         if (burstbytes < size * 2)
 183                                 goto single_block_read;
 184                         if (nblks > burstbytes / size)
 185                                 nblks = burstbytes / size;
 186
 187                         bp = cluster_rbuild(vp, filesize, loffset,
 188                                             doffset, size, nblks, bp);
 189                         loffset += bp->b_bufsize;
 190                 } else {
 191 single_block_read:
 192                         /*
 193                          * if it isn't in the cache, then get a chunk from
 194                          * disk if sequential, otherwise just get the block.
 195                          */
 196                         bp->b_flags |= B_READ | B_RAM;
 197                         loffset += size;
 198                 }
 199         }
 200
 201         /*
 202          * If we have been doing sequential I/O, then do some read-ahead.
 203          */
 204         rbp = NULL;
 205         if (seqcount &&
 206             loffset < origoffset + seqcount * size &&
 207             loffset + size <= filesize
 208         ) {
 209                 rbp = getblk(vp, loffset, size, 0, 0);
 210                 if ((rbp->b_flags & B_CACHE) == 0) {
 211                         int nblksread;
 212                         int ntoread;
 213                         int burstbytes;
 214
 215                         error = VOP_BMAP(vp, loffset, NULL,
 216                                          &doffset, &burstbytes, NULL);
 217                         if (error || doffset == NOOFFSET) {
 218                                 rbp->b_flags &= ~(B_ASYNC | B_READ);
 219                                 brelse(rbp);
 220                                 rbp = NULL;
 221                                 goto no_read_ahead;
 222                         }
 223                         ntoread = burstbytes / size;
 224                         nblksread = (totread + size - 1) / size;
 225                         if (seqcount < nblksread)
 226                                 seqcount = nblksread;
 227                         if (seqcount < ntoread)
 228                                 ntoread = seqcount;
 229
 230                         rbp->b_flags |= B_READ | B_ASYNC | B_RAM;
 231                         if (burstbytes) {
 232                                 rbp = cluster_rbuild(vp, filesize, loffset,
 233                                                      doffset, size,
 234                                                      ntoread, rbp);
 235                         } else {
 236                                 rbp->b_bio2.bio_offset = doffset;
 237                         }
 238                 }
 239         }
 240 no_read_ahead:
 241
 242         /*
 243          * Handle the synchronous read.  This only occurs if B_CACHE was
 244          * not set.
 245          */
 246         if (bp) {
 247 #if defined(CLUSTERDEBUG)
 248                 if (rcluster)
 249                         printf("S(%lld,%d,%d) ",
 250                             bp->b_loffset, bp->b_bcount, seqcount);
 251 #endif
 252                 if ((bp->b_flags & B_CLUSTER) == 0) {
 253                         vfs_busy_pages(vp, bp, 0);
 254                 }
 255                 bp->b_flags &= ~(B_ERROR|B_INVAL);
 256                 if ((bp->b_flags & B_ASYNC) || bp->b_bio1.bio_done != NULL)
 257                         BUF_KERNPROC(bp);
 258                 vn_strategy(vp, &bp->b_bio1);
 259                 error = bp->b_error;
 260         }
 261
 262         /*
 263          * And if we have read-aheads, do them too
 264          */
 265         if (rbp) {
 266                 if (error) {
 267                         rbp->b_flags &= ~(B_ASYNC | B_READ);
 268                         brelse(rbp);
 269                 } else if (rbp->b_flags & B_CACHE) {
 270                         rbp->b_flags &= ~(B_ASYNC | B_READ);
 271                         bqrelse(rbp);
 272                 } else {
 273 #if defined(CLUSTERDEBUG)
 274                         if (rcluster) {
 275                                 if (bp)
 276                                         printf("A+(%lld,%d,%lld,%d) ",
 277                                             rbp->b_loffset, rbp->b_bcount,
 278                                             rbp->b_loffset - origoffset,
 279                                             seqcount);
 280                                 else
 281                                         printf("A(%lld,%d,%lld,%d) ",
 282                                             rbp->b_loffset, rbp->b_bcount,
 283                                             rbp->b_loffset - origoffset,
 284                                             seqcount);
 285                         }
 286 #endif
 287
 288                         if ((rbp->b_flags & B_CLUSTER) == 0) {
 289                                 vfs_busy_pages(vp, rbp, 0);
 290                         }
 291                         rbp->b_flags &= ~(B_ERROR|B_INVAL);
 292                         if ((rbp->b_flags & B_ASYNC) || rbp->b_bio1.bio_done != NULL)
 293                                 BUF_KERNPROC(rbp);
 294                         vn_strategy(vp, &rbp->b_bio1);
 295                 }
 296         }
 297         if (reqbp)
 298                 return (biowait(reqbp));
 299         else
 300                 return (error);
 301 }
 302
 303 /*
 304  * If blocks are contiguous on disk, use this to provide clustered
 305  * read ahead.  We will read as many blocks as possible sequentially
 306  * and then parcel them up into logical blocks in the buffer hash table.
 307  */
 308 static struct buf *
 309 cluster_rbuild(struct vnode *vp, off_t filesize, off_t loffset,
 310         off_t doffset, int size, int run, struct buf *fbp)
 311 {
 312         struct buf *bp, *tbp;
 313         off_t boffset;
 314         int i, j;
 315
 316         KASSERT(size == vp->v_mount->mnt_stat.f_iosize,
 317             ("cluster_rbuild: size %d != filesize %ld\n",
 318             size, vp->v_mount->mnt_stat.f_iosize));
 319
 320         /*
 321          * avoid a division
 322          */
 323         while (loffset + run * size > filesize) {
 324                 --run;
 325         }
 326
 327         tbp = fbp;
 328         tbp->b_flags |= B_READ;
 329         tbp->b_bio2.bio_offset = doffset;
 330         if( (tbp->b_flags & B_MALLOC) ||
 331                 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1) )
 332                 return tbp;
 333
 334         bp = trypbuf(&cluster_pbuf_freecnt);
 335         if (bp == NULL)
 336                 return tbp;
 337
 338         /*
 339          * We are synthesizing a buffer out of vm_page_t's, but
 340          * if the block size is not page aligned then the starting
 341          * address may not be either.  Inherit the b_data offset
 342          * from the original buffer.
 343          */
 344         bp->b_data = (char *)((vm_offset_t)bp->b_data |
 345             ((vm_offset_t)tbp->b_data & PAGE_MASK));
 346         bp->b_flags |= B_ASYNC | B_READ | B_CLUSTER | B_VMIO;
 347         bp->b_bio1.bio_done = cluster_callback;
 348         bp->b_bio1.bio_caller_info1.cluster_head = NULL;
 349         bp->b_bio1.bio_caller_info2.cluster_tail = NULL;
 350         bp->b_loffset = loffset;
 351         bp->b_bio2.bio_offset = NOOFFSET;
 352         KASSERT(bp->b_loffset != NOOFFSET,
 353                 ("cluster_rbuild: no buffer offset"));
 354
 355         bp->b_bcount = 0;
 356         bp->b_bufsize = 0;
 357         bp->b_xio.xio_npages = 0;
 358
 359         for (boffset = doffset, i = 0; i < run; ++i, boffset += size) {
 360                 if (i != 0) {
 361                         if ((bp->b_xio.xio_npages * PAGE_SIZE) +
 362                             round_page(size) > vp->v_mount->mnt_iosize_max) {
 363                                 break;
 364                         }
 365
 366                         /*
 367                          * Shortcut some checks and try to avoid buffers that
 368                          * would block in the lock.  The same checks have to
 369                          * be made again after we officially get the buffer.
 370                          */
 371                         if ((tbp = findblk(vp, loffset + i * size)) != NULL) {
 372                                 if (BUF_LOCK(tbp, LK_EXCLUSIVE | LK_NOWAIT))
 373                                         break;
 374                                 BUF_UNLOCK(tbp);
 375
 376                                 for (j = 0; j < tbp->b_xio.xio_npages; j++) {
 377                                         if (tbp->b_xio.xio_pages[j]->valid)
 378                                                 break;
 379                                 }
 380
 381                                 if (j != tbp->b_xio.xio_npages)
 382                                         break;
 383
 384                                 if (tbp->b_bcount != size)
 385                                         break;
 386                         }
 387
 388                         tbp = getblk(vp, loffset + i * size, size, 0, 0);
 389
 390                         /*
 391                          * Stop scanning if the buffer is fuly valid
 392                          * (marked B_CACHE), or locked (may be doing a
 393                          * background write), or if the buffer is not
 394                          * VMIO backed.  The clustering code can only deal
 395                          * with VMIO-backed buffers.
 396                          */
 397                         if ((tbp->b_flags & (B_CACHE|B_LOCKED)) ||
 398                             (tbp->b_flags & B_VMIO) == 0) {
 399                                 bqrelse(tbp);
 400                                 break;
 401                         }
 402
 403                         /*
 404                          * The buffer must be completely invalid in order to
 405                          * take part in the cluster.  If it is partially valid
 406                          * then we stop.
 407                          */
 408                         for (j = 0;j < tbp->b_xio.xio_npages; j++) {
 409                                 if (tbp->b_xio.xio_pages[j]->valid)
 410                                         break;
 411                         }
 412                         if (j != tbp->b_xio.xio_npages) {
 413                                 bqrelse(tbp);
 414                                 break;
 415                         }
 416
 417                         /*
 418                          * Set a read-ahead mark as appropriate
 419                          */
 420                         if (i == 1 || i == (run - 1))
 421                                 tbp->b_flags |= B_RAM;
 422
 423                         /*
 424                          * Set the buffer up for an async read (XXX should
 425                          * we do this only if we do not wind up brelse()ing?).
 426                          * Set the block number if it isn't set, otherwise
 427                          * if it is make sure it matches the block number we
 428                          * expect.
 429                          */
 430                         tbp->b_flags |= B_READ | B_ASYNC;
 431                         if (tbp->b_bio2.bio_offset == NOOFFSET) {
 432                                 tbp->b_bio2.bio_offset = boffset;
 433                         } else if (tbp->b_bio2.bio_offset != boffset) {
 434                                 brelse(tbp);
 435                                 break;
 436                         }
 437                 }
 438                 /*
 439                  * XXX fbp from caller may not be B_ASYNC, but we are going
 440                  * to biodone() it in cluster_callback() anyway
 441                  */
 442                 BUF_KERNPROC(tbp);
 443                 cluster_append(&bp->b_bio1, tbp);
 444                 for (j = 0; j < tbp->b_xio.xio_npages; ++j) {
 445                         vm_page_t m;
 446                         m = tbp->b_xio.xio_pages[j];
 447                         vm_page_io_start(m);
 448                         vm_object_pip_add(m->object, 1);
 449                         if ((bp->b_xio.xio_npages == 0) ||
 450                                 (bp->b_xio.xio_pages[bp->b_xio.xio_npages-1] != m)) {
 451                                 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m;
 452                                 bp->b_xio.xio_npages++;
 453                         }
 454                         if ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL)
 455                                 tbp->b_xio.xio_pages[j] = bogus_page;
 456                 }
 457                 /*
 458                  * XXX shouldn't this be += size for both, like in
 459                  * cluster_wbuild()?
 460                  *
 461                  * Don't inherit tbp->b_bufsize as it may be larger due to
 462                  * a non-page-aligned size.  Instead just aggregate using
 463                  * 'size'.
 464                  */
 465                 if (tbp->b_bcount != size)
 466                     printf("warning: tbp->b_bcount wrong %d vs %d\n", tbp->b_bcount, size);
 467                 if (tbp->b_bufsize != size)
 468                     printf("warning: tbp->b_bufsize wrong %d vs %d\n", tbp->b_bufsize, size);
 469                 bp->b_bcount += size;
 470                 bp->b_bufsize += size;
 471         }
 472
 473         /*
 474          * Fully valid pages in the cluster are already good and do not need
 475          * to be re-read from disk.  Replace the page with bogus_page
 476          */
 477         for (j = 0; j < bp->b_xio.xio_npages; j++) {
 478                 if ((bp->b_xio.xio_pages[j]->valid & VM_PAGE_BITS_ALL) ==
 479                     VM_PAGE_BITS_ALL) {
 480                         bp->b_xio.xio_pages[j] = bogus_page;
 481                 }
 482         }
 483         if (bp->b_bufsize > bp->b_kvasize)
 484                 panic("cluster_rbuild: b_bufsize(%d) > b_kvasize(%d)",
 485                     bp->b_bufsize, bp->b_kvasize);
 486         bp->b_kvasize = bp->b_bufsize;
 487
 488         pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
 489                 (vm_page_t *)bp->b_xio.xio_pages, bp->b_xio.xio_npages);
 490         return (bp);
 491 }
 492
 493 /*
 494  * Cleanup after a clustered read or write.
 495  * This is complicated by the fact that any of the buffers might have
 496  * extra memory (if there were no empty buffer headers at allocbuf time)
 497  * that we will need to shift around.
 498  *
 499  * The returned bio is &bp->b_bio1
 500  */
 501 void
 502 cluster_callback(struct bio *bio)
 503 {
 504         struct buf *bp = bio->bio_buf;
 505         struct buf *tbp;
 506         int error = 0;
 507
 508         /*
 509          * Must propogate errors to all the components.
 510          */
 511         if (bp->b_flags & B_ERROR)
 512                 error = bp->b_error;
 513
 514         pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_xio.xio_npages);
 515         /*
 516          * Move memory from the large cluster buffer into the component
 517          * buffers and mark IO as done on these.  Since the memory map
 518          * is the same, no actual copying is required.
 519          */
 520         while ((tbp = bio->bio_caller_info1.cluster_head) != NULL) {
 521                 bio->bio_caller_info1.cluster_head = tbp->b_cluster_next;
 522                 if (error) {
 523                         tbp->b_flags |= B_ERROR;
 524                         tbp->b_error = error;
 525                 } else {
 526                         tbp->b_dirtyoff = tbp->b_dirtyend = 0;
 527                         tbp->b_flags &= ~(B_ERROR|B_INVAL);
 528                         /*
 529                          * XXX the bdwrite()/bqrelse() issued during
 530                          * cluster building clears B_RELBUF (see bqrelse()
 531                          * comment).  If direct I/O was specified, we have
 532                          * to restore it here to allow the buffer and VM
 533                          * to be freed.
 534                          */
 535                         if (tbp->b_flags & B_DIRECT)
 536                                 tbp->b_flags |= B_RELBUF;
 537                 }
 538                 biodone(&tbp->b_bio1);
 539         }
 540         relpbuf(bp, &cluster_pbuf_freecnt);
 541 }
 542
 543 /*
 544  *      cluster_wbuild_wb:
 545  *
 546  *      Implement modified write build for cluster.
 547  *
 548  *              write_behind = 0        write behind disabled
 549  *              write_behind = 1        write behind normal (default)
 550  *              write_behind = 2        write behind backed-off
 551  */
 552
 553 static __inline int
 554 cluster_wbuild_wb(struct vnode *vp, int size, off_t start_loffset, int len)
 555 {
 556         int r = 0;
 557
 558         switch(write_behind) {
 559         case 2:
 560                 if (start_loffset < len)
 561                         break;
 562                 start_loffset -= len;
 563                 /* fall through */
 564         case 1:
 565                 r = cluster_wbuild(vp, size, start_loffset, len);
 566                 /* fall through */
 567         default:
 568                 /* fall through */
 569                 break;
 570         }
 571         return(r);
 572 }
 573
 574 /*
 575  * Do clustered write for FFS.
 576  *
 577  * Three cases:
 578  *      1. Write is not sequential (write asynchronously)
 579  *      Write is sequential:
 580  *      2.      beginning of cluster - begin cluster
 581  *      3.      middle of a cluster - add to cluster
 582  *      4.      end of a cluster - asynchronously write cluster
 583  */
 584 void
 585 cluster_write(struct buf *bp, off_t filesize, int seqcount)
 586 {
 587         struct vnode *vp;
 588         off_t loffset;
 589         int maxclen, cursize;
 590         int lblocksize;
 591         int async;
 592
 593         vp = bp->b_vp;
 594         if (vp->v_type == VREG) {
 595                 async = vp->v_mount->mnt_flag & MNT_ASYNC;
 596                 lblocksize = vp->v_mount->mnt_stat.f_iosize;
 597         } else {
 598                 async = 0;
 599                 lblocksize = bp->b_bufsize;
 600         }
 601         loffset = bp->b_loffset;
 602         KASSERT(bp->b_loffset != NOOFFSET,
 603                 ("cluster_write: no buffer offset"));
 604
 605         /* Initialize vnode to beginning of file. */
 606         if (loffset == 0)
 607                 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0;
 608
 609         if (vp->v_clen == 0 || loffset != vp->v_lastw + lblocksize ||
 610             bp->b_bio2.bio_offset == NOOFFSET ||
 611             (bp->b_bio2.bio_offset != vp->v_lasta + lblocksize)) {
 612                 maxclen = vp->v_mount->mnt_iosize_max;
 613                 if (vp->v_clen != 0) {
 614                         /*
 615                          * Next block is not sequential.
 616                          *
 617                          * If we are not writing at end of file, the process
 618                          * seeked to another point in the file since its last
 619                          * write, or we have reached our maximum cluster size,
 620                          * then push the previous cluster. Otherwise try
 621                          * reallocating to make it sequential.
 622                          *
 623                          * Change to algorithm: only push previous cluster if
 624                          * it was sequential from the point of view of the
 625                          * seqcount heuristic, otherwise leave the buffer
 626                          * intact so we can potentially optimize the I/O
 627                          * later on in the buf_daemon or update daemon
 628                          * flush.
 629                          */
 630                         cursize = vp->v_lastw - vp->v_cstart + lblocksize;
 631                         if (bp->b_loffset + lblocksize != filesize ||
 632                             loffset != vp->v_lastw + lblocksize || vp->v_clen <= cursize) {
 633                                 if (!async && seqcount > 0) {
 634                                         cluster_wbuild_wb(vp, lblocksize,
 635                                                 vp->v_cstart, cursize);
 636                                 }
 637                         } else {
 638                                 struct buf **bpp, **endbp;
 639                                 struct cluster_save *buflist;
 640
 641                                 buflist = cluster_collectbufs(vp, bp,
 642                                                               lblocksize);
 643                                 endbp = &buflist->bs_children
 644                                     [buflist->bs_nchildren - 1];
 645                                 if (VOP_REALLOCBLKS(vp, buflist)) {
 646                                         /*
 647                                          * Failed, push the previous cluster
 648                                          * if *really* writing sequentially
 649                                          * in the logical file (seqcount > 1),
 650                                          * otherwise delay it in the hopes that
 651                                          * the low level disk driver can
 652                                          * optimize the write ordering.
 653                                          */
 654                                         for (bpp = buflist->bs_children;
 655                                              bpp < endbp; bpp++)
 656                                                 brelse(*bpp);
 657                                         free(buflist, M_SEGMENT);
 658                                         if (seqcount > 1) {
 659                                                 cluster_wbuild_wb(vp,
 660                                                     lblocksize, vp->v_cstart,
 661                                                     cursize);
 662                                         }
 663                                 } else {
 664                                         /*
 665                                          * Succeeded, keep building cluster.
 666                                          */
 667                                         for (bpp = buflist->bs_children;
 668                                              bpp <= endbp; bpp++)
 669                                                 bdwrite(*bpp);
 670                                         free(buflist, M_SEGMENT);
 671                                         vp->v_lastw = loffset;
 672                                         vp->v_lasta = bp->b_bio2.bio_offset;
 673                                         return;
 674                                 }
 675                         }
 676                 }
 677                 /*
 678                  * Consider beginning a cluster. If at end of file, make
 679                  * cluster as large as possible, otherwise find size of
 680                  * existing cluster.
 681                  */
 682                 if ((vp->v_type == VREG) &&
 683                     bp->b_loffset + lblocksize != filesize &&
 684                     (bp->b_bio2.bio_offset == NOOFFSET) &&
 685                     (VOP_BMAP(vp, loffset, NULL, &bp->b_bio2.bio_offset, &maxclen, NULL) ||
 686                      bp->b_bio2.bio_offset == NOOFFSET)) {
 687                         bawrite(bp);
 688                         vp->v_clen = 0;
 689                         vp->v_lasta = bp->b_bio2.bio_offset;
 690                         vp->v_cstart = loffset + lblocksize;
 691                         vp->v_lastw = loffset;
 692                         return;
 693                 }
 694                 if (maxclen > lblocksize)
 695                         vp->v_clen = maxclen - lblocksize;
 696                 else
 697                         vp->v_clen = 0;
 698                 if (!async && vp->v_clen == 0) { /* I/O not contiguous */
 699                         vp->v_cstart = loffset + lblocksize;
 700                         bawrite(bp);
 701                 } else {        /* Wait for rest of cluster */
 702                         vp->v_cstart = loffset;
 703                         bdwrite(bp);
 704                 }
 705         } else if (loffset == vp->v_cstart + vp->v_clen) {
 706                 /*
 707                  * At end of cluster, write it out if seqcount tells us we
 708                  * are operating sequentially, otherwise let the buf or
 709                  * update daemon handle it.
 710                  */
 711                 bdwrite(bp);
 712                 if (seqcount > 1)
 713                         cluster_wbuild_wb(vp, lblocksize, vp->v_cstart,
 714                                           vp->v_clen + lblocksize);
 715                 vp->v_clen = 0;
 716                 vp->v_cstart = loffset + lblocksize;
 717         } else if (vm_page_count_severe()) {
 718                 /*
 719                  * We are low on memory, get it going NOW
 720                  */
 721                 bawrite(bp);
 722         } else {
 723                 /*
 724                  * In the middle of a cluster, so just delay the I/O for now.
 725                  */
 726                 bdwrite(bp);
 727         }
 728         vp->v_lastw = loffset;
 729         vp->v_lasta = bp->b_bio2.bio_offset;
 730 }
 731
 732
 733 /*
 734  * This is an awful lot like cluster_rbuild...wish they could be combined.
 735  * The last lbn argument is the current block on which I/O is being
 736  * performed.  Check to see that it doesn't fall in the middle of
 737  * the current block (if last_bp == NULL).
 738  */
 739 int
 740 cluster_wbuild(struct vnode *vp, int size, off_t start_loffset, int bytes)
 741 {
 742         struct buf *bp, *tbp;
 743         int i, j;
 744         int totalwritten = 0;
 745
 746         while (bytes > 0) {
 747                 crit_enter();
 748                 /*
 749                  * If the buffer is not delayed-write (i.e. dirty), or it
 750                  * is delayed-write but either locked or inval, it cannot
 751                  * partake in the clustered write.
 752                  */
 753                 if (((tbp = findblk(vp, start_loffset)) == NULL) ||
 754                   ((tbp->b_flags & (B_LOCKED | B_INVAL | B_DELWRI)) != B_DELWRI) ||
 755                   BUF_LOCK(tbp, LK_EXCLUSIVE | LK_NOWAIT)) {
 756                         start_loffset += size;
 757                         bytes -= size;
 758                         crit_exit();
 759                         continue;
 760                 }
 761                 bremfree(tbp);
 762                 tbp->b_flags &= ~B_DONE;
 763                 crit_exit();
 764
 765                 /*
 766                  * Extra memory in the buffer, punt on this buffer.
 767                  * XXX we could handle this in most cases, but we would
 768                  * have to push the extra memory down to after our max
 769                  * possible cluster size and then potentially pull it back
 770                  * up if the cluster was terminated prematurely--too much
 771                  * hassle.
 772                  */
 773                 if (((tbp->b_flags & (B_CLUSTEROK|B_MALLOC)) != B_CLUSTEROK) ||
 774                   (tbp->b_bcount != tbp->b_bufsize) ||
 775                   (tbp->b_bcount != size) ||
 776                   (bytes == size) ||
 777                   ((bp = getpbuf(&cluster_pbuf_freecnt)) == NULL)) {
 778                         totalwritten += tbp->b_bufsize;
 779                         bawrite(tbp);
 780                         start_loffset += size;
 781                         bytes -= size;
 782                         continue;
 783                 }
 784
 785                 /*
 786                  * We got a pbuf to make the cluster in.
 787                  * so initialise it.
 788                  */
 789                 bp->b_bcount = 0;
 790                 bp->b_bufsize = 0;
 791                 bp->b_xio.xio_npages = 0;
 792                 bp->b_loffset = tbp->b_loffset;
 793                 bp->b_bio2.bio_offset = tbp->b_bio2.bio_offset;
 794
 795                 /*
 796                  * We are synthesizing a buffer out of vm_page_t's, but
 797                  * if the block size is not page aligned then the starting
 798                  * address may not be either.  Inherit the b_data offset
 799                  * from the original buffer.
 800                  */
 801                 bp->b_data = (char *)((vm_offset_t)bp->b_data |
 802                     ((vm_offset_t)tbp->b_data & PAGE_MASK));
 803                 bp->b_flags &= ~(B_READ | B_DONE | B_ERROR);
 804                 bp->b_flags |= B_CLUSTER | B_ASYNC |
 805                         (tbp->b_flags & (B_VMIO | B_NEEDCOMMIT | B_NOWDRAIN));
 806                 bp->b_bio1.bio_done = cluster_callback;
 807                 bp->b_bio1.bio_caller_info1.cluster_head = NULL;
 808                 bp->b_bio1.bio_caller_info2.cluster_tail = NULL;
 809                 /*
 810                  * From this location in the file, scan forward to see
 811                  * if there are buffers with adjacent data that need to
 812                  * be written as well.
 813                  */
 814                 for (i = 0; i < bytes; (i += size), (start_loffset += size)) {
 815                         if (i != 0) { /* If not the first buffer */
 816                                 crit_enter();
 817                                 /*
 818                                  * If the adjacent data is not even in core it
 819                                  * can't need to be written.
 820                                  */
 821                                 if ((tbp = findblk(vp, start_loffset)) == NULL) {
 822                                         crit_exit();
 823                                         break;
 824                                 }
 825
 826                                 /*
 827                                  * If it IS in core, but has different
 828                                  * characteristics, or is locked (which
 829                                  * means it could be undergoing a background
 830                                  * I/O or be in a weird state), then don't
 831                                  * cluster with it.
 832                                  */
 833                                 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK |
 834                                     B_INVAL | B_DELWRI | B_NEEDCOMMIT))
 835                                   != (B_DELWRI | B_CLUSTEROK |
 836                                     (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) ||
 837                                     (tbp->b_flags & B_LOCKED) ||
 838                                     BUF_LOCK(tbp, LK_EXCLUSIVE | LK_NOWAIT)) {
 839                                         crit_exit();
 840                                         break;
 841                                 }
 842
 843                                 /*
 844                                  * Check that the combined cluster
 845                                  * would make sense with regard to pages
 846                                  * and would not be too large
 847                                  */
 848                                 if ((tbp->b_bcount != size) ||
 849                                   ((bp->b_bio2.bio_offset + i) !=
 850                                     tbp->b_bio2.bio_offset) ||
 851                                   ((tbp->b_xio.xio_npages + bp->b_xio.xio_npages) >
 852                                     (vp->v_mount->mnt_iosize_max / PAGE_SIZE))) {
 853                                         BUF_UNLOCK(tbp);
 854                                         crit_exit();
 855                                         break;
 856                                 }
 857                                 /*
 858                                  * Ok, it's passed all the tests,
 859                                  * so remove it from the free list
 860                                  * and mark it busy. We will use it.
 861                                  */
 862                                 bremfree(tbp);
 863                                 tbp->b_flags &= ~B_DONE;
 864                                 crit_exit();
 865                         } /* end of code for non-first buffers only */
 866
 867                         /*
 868                          * If the IO is via the VM then we do some
 869                          * special VM hackery (yuck).  Since the buffer's
 870                          * block size may not be page-aligned it is possible
 871                          * for a page to be shared between two buffers.  We
 872                          * have to get rid of the duplication when building
 873                          * the cluster.
 874                          */
 875                         if (tbp->b_flags & B_VMIO) {
 876                                 vm_page_t m;
 877
 878                                 if (i != 0) { /* if not first buffer */
 879                                         for (j = 0; j < tbp->b_xio.xio_npages; ++j) {
 880                                                 m = tbp->b_xio.xio_pages[j];
 881                                                 if (m->flags & PG_BUSY) {
 882                                                         bqrelse(tbp);
 883                                                         goto finishcluster;
 884                                                 }
 885                                         }
 886                                 }
 887
 888                                 for (j = 0; j < tbp->b_xio.xio_npages; ++j) {
 889                                         m = tbp->b_xio.xio_pages[j];
 890                                         vm_page_io_start(m);
 891                                         vm_object_pip_add(m->object, 1);
 892                                         if ((bp->b_xio.xio_npages == 0) ||
 893                                           (bp->b_xio.xio_pages[bp->b_xio.xio_npages - 1] != m)) {
 894                                                 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m;
 895                                                 bp->b_xio.xio_npages++;
 896                                         }
 897                                 }
 898                         }
 899                         bp->b_bcount += size;
 900                         bp->b_bufsize += size;
 901
 902                         crit_enter();
 903                         bundirty(tbp);
 904                         tbp->b_flags &= ~(B_READ | B_DONE | B_ERROR);
 905                         tbp->b_flags |= B_ASYNC;
 906                         crit_exit();
 907                         BUF_KERNPROC(tbp);
 908                         cluster_append(&bp->b_bio1, tbp);
 909
 910                         /*
 911                          * check for latent dependencies to be handled
 912                          */
 913                         if (LIST_FIRST(&tbp->b_dep) != NULL && bioops.io_start)
 914                                 (*bioops.io_start)(tbp);
 915
 916                 }
 917         finishcluster:
 918                 pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
 919                         (vm_page_t *) bp->b_xio.xio_pages, bp->b_xio.xio_npages);
 920                 if (bp->b_bufsize > bp->b_kvasize)
 921                         panic(
 922                             "cluster_wbuild: b_bufsize(%d) > b_kvasize(%d)\n",
 923                             bp->b_bufsize, bp->b_kvasize);
 924                 bp->b_kvasize = bp->b_bufsize;
 925                 totalwritten += bp->b_bufsize;
 926                 bp->b_dirtyoff = 0;
 927                 bp->b_dirtyend = bp->b_bufsize;
 928
 929                 vfs_busy_pages(vp, bp, 1);
 930                 bp->b_runningbufspace = bp->b_bufsize;
 931                 runningbufspace += bp->b_runningbufspace;
 932                 BUF_KERNPROC(bp);       /* B_ASYNC */
 933                 vn_strategy(vp, &bp->b_bio1);
 934
 935                 bytes -= i;
 936         }
 937         return totalwritten;
 938 }
 939
 940 /*
 941  * Collect together all the buffers in a cluster.
 942  * Plus add one additional buffer.
 943  */
 944 static struct cluster_save *
 945 cluster_collectbufs(struct vnode *vp, struct buf *last_bp, int lblocksize)
 946 {
 947         struct cluster_save *buflist;
 948         struct buf *bp;
 949         off_t loffset;
 950         int i, len;
 951
 952         len = (int)(vp->v_lastw - vp->v_cstart + lblocksize) / lblocksize;
 953         buflist = malloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist),
 954                          M_SEGMENT, M_WAITOK);
 955         buflist->bs_nchildren = 0;
 956         buflist->bs_children = (struct buf **) (buflist + 1);
 957         for (loffset = vp->v_cstart, i = 0; i < len; (loffset += lblocksize), i++) {
 958                 (void) bread(vp, loffset, last_bp->b_bcount, &bp);
 959                 buflist->bs_children[i] = bp;
 960                 if (bp->b_bio2.bio_offset == NOOFFSET) {
 961                         VOP_BMAP(bp->b_vp, bp->b_loffset, NULL,
 962                                 &bp->b_bio2.bio_offset, NULL, NULL);
 963                 }
 964         }
 965         buflist->bs_children[i] = bp = last_bp;
 966         if (bp->b_bio2.bio_offset == NOOFFSET) {
 967                 VOP_BMAP(bp->b_vp, bp->b_loffset, NULL,
 968                          &bp->b_bio2.bio_offset, NULL, NULL);
 969         }
 970         buflist->bs_nchildren = i + 1;
 971         return (buflist);
 972 }
 973
 974 void
 975 cluster_append(struct bio *bio, struct buf *tbp)
 976 {
 977         tbp->b_cluster_next = NULL;
 978         if (bio->bio_caller_info1.cluster_head == NULL) {
 979                 bio->bio_caller_info1.cluster_head = tbp;
 980                 bio->bio_caller_info2.cluster_tail = tbp;
 981         } else {
 982                 bio->bio_caller_info2.cluster_tail->b_cluster_next = tbp;
 983                 bio->bio_caller_info2.cluster_tail = tbp;
 984         }
 985 }
 986