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  * 4. Neither the name of the University nor the names of its contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  *
  31  *      @(#)vfs_cluster.c       8.7 (Berkeley) 2/13/94
  32  */
  33
  34 #include <sys/cdefs.h>
  35 __FBSDID("$FreeBSD$");
  36
  37 #include "opt_debug_cluster.h"
  38
  39 #include <sys/param.h>
  40 #include <sys/systm.h>
  41 #include <sys/kernel.h>
  42 #include <sys/proc.h>
  43 #include <sys/bio.h>
  44 #include <sys/buf.h>
  45 #include <sys/vnode.h>
  46 #include <sys/malloc.h>
  47 #include <sys/mount.h>
  48 #include <sys/resourcevar.h>
  49 #include <sys/vmmeter.h>
  50 #include <vm/vm.h>
  51 #include <vm/vm_object.h>
  52 #include <vm/vm_page.h>
  53 #include <sys/sysctl.h>
  54
  55 #if defined(CLUSTERDEBUG)
  56 static int      rcluster= 0;
  57 SYSCTL_INT(_debug, OID_AUTO, rcluster, CTLFLAG_RW, &rcluster, 0,
  58     "Debug VFS clustering code");
  59 #endif
  60
  61 static MALLOC_DEFINE(M_SEGMENT, "cluster_save buffer", "cluster_save buffer");
  62
  63 static struct cluster_save *
  64         cluster_collectbufs(struct vnode *vp, struct buf *last_bp);
  65 static struct buf *
  66         cluster_rbuild(struct vnode *vp, u_quad_t filesize, daddr_t lbn,
  67                          daddr_t blkno, long size, int run, struct buf *fbp);
  68
  69 static int write_behind = 1;
  70 SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0,
  71     "Cluster write-behind; 0: disable, 1: enable, 2: backed off");
  72
  73 static int read_max = 8;
  74 SYSCTL_INT(_vfs, OID_AUTO, read_max, CTLFLAG_RW, &read_max, 0,
  75     "Cluster read-ahead max block count");
  76
  77 /* Page expended to mark partially backed buffers */
  78 extern vm_page_t        bogus_page;
  79
  80 /*
  81  * Number of physical bufs (pbufs) this subsystem is allowed.
  82  * Manipulated by vm_pager.c
  83  */
  84 extern int cluster_pbuf_freecnt;
  85
  86 /*
  87  * Read data to a buf, including read-ahead if we find this to be beneficial.
  88  * cluster_read replaces bread.
  89  */
  90 int
  91 cluster_read(vp, filesize, lblkno, size, cred, totread, seqcount, bpp)
  92         struct vnode *vp;
  93         u_quad_t filesize;
  94         daddr_t lblkno;
  95         long size;
  96         struct ucred *cred;
  97         long totread;
  98         int seqcount;
  99         struct buf **bpp;
 100 {
 101         struct buf *bp, *rbp, *reqbp;
 102         daddr_t blkno, origblkno;
 103         int maxra, racluster;
 104         int error, ncontig;
 105         int i;
 106
 107         error = 0;
 108
 109         /*
 110          * Try to limit the amount of read-ahead by a few
 111          * ad-hoc parameters.  This needs work!!!
 112          */
 113         racluster = vp->v_mount->mnt_iosize_max / size;
 114         maxra = seqcount;
 115         maxra = min(read_max, maxra);
 116         maxra = min(nbuf/8, maxra);
 117         if (((u_quad_t)(lblkno + maxra + 1) * size) > filesize)
 118                 maxra = (filesize / size) - lblkno;
 119
 120         /*
 121          * get the requested block
 122          */
 123         *bpp = reqbp = bp = getblk(vp, lblkno, size, 0, 0, 0);
 124         origblkno = lblkno;
 125
 126         /*
 127          * if it is in the cache, then check to see if the reads have been
 128          * sequential.  If they have, then try some read-ahead, otherwise
 129          * back-off on prospective read-aheads.
 130          */
 131         if (bp->b_flags & B_CACHE) {
 132                 if (!seqcount) {
 133                         return 0;
 134                 } else if ((bp->b_flags & B_RAM) == 0) {
 135                         return 0;
 136                 } else {
 137                         int s;
 138                         bp->b_flags &= ~B_RAM;
 139                         /*
 140                          * We do the spl here so that there is no window
 141                          * between the incore and the b_usecount increment
 142                          * below.  We opt to keep the spl out of the loop
 143                          * for efficiency.
 144                          */
 145                         s = splbio();
 146                         VI_LOCK(vp);
 147                         for (i = 1; i < maxra; i++) {
 148                                 /*
 149                                  * Stop if the buffer does not exist or it
 150                                  * is invalid (about to go away?)
 151                                  */
 152                                 rbp = gbincore(vp, lblkno+i);
 153                                 if (rbp == NULL || (rbp->b_flags & B_INVAL))
 154                                         break;
 155
 156                                 /*
 157                                  * Set another read-ahead mark so we know
 158                                  * to check again.
 159                                  */
 160                                 if (((i % racluster) == (racluster - 1)) ||
 161                                         (i == (maxra - 1)))
 162                                         rbp->b_flags |= B_RAM;
 163                         }
 164                         VI_UNLOCK(vp);
 165                         splx(s);
 166                         if (i >= maxra) {
 167                                 return 0;
 168                         }
 169                         lblkno += i;
 170                 }
 171                 reqbp = bp = NULL;
 172         /*
 173          * If it isn't in the cache, then get a chunk from
 174          * disk if sequential, otherwise just get the block.
 175          */
 176         } else {
 177                 off_t firstread = bp->b_offset;
 178                 int nblks;
 179
 180                 KASSERT(bp->b_offset != NOOFFSET,
 181                     ("cluster_read: no buffer offset"));
 182
 183                 ncontig = 0;
 184
 185                 /*
 186                  * Compute the total number of blocks that we should read
 187                  * synchronously.
 188                  */
 189                 if (firstread + totread > filesize)
 190                         totread = filesize - firstread;
 191                 nblks = howmany(totread, size);
 192                 if (nblks > racluster)
 193                         nblks = racluster;
 194
 195                 /*
 196                  * Now compute the number of contiguous blocks.
 197                  */
 198                 if (nblks > 1) {
 199                         error = VOP_BMAP(vp, lblkno, NULL,
 200                                 &blkno, &ncontig, NULL);
 201                         /*
 202                          * If this failed to map just do the original block.
 203                          */
 204                         if (error || blkno == -1)
 205                                 ncontig = 0;
 206                 }
 207
 208                 /*
 209                  * If we have contiguous data available do a cluster
 210                  * otherwise just read the requested block.
 211                  */
 212                 if (ncontig) {
 213                         /* Account for our first block. */
 214                         ncontig = min(ncontig + 1, nblks);
 215                         if (ncontig < nblks)
 216                                 nblks = ncontig;
 217                         bp = cluster_rbuild(vp, filesize, lblkno,
 218                                 blkno, size, nblks, bp);
 219                         lblkno += (bp->b_bufsize / size);
 220                 } else {
 221                         bp->b_flags |= B_RAM;
 222                         bp->b_iocmd = BIO_READ;
 223                         lblkno += 1;
 224                 }
 225         }
 226
 227         /*
 228          * handle the synchronous read so that it is available ASAP.
 229          */
 230         if (bp) {
 231                 if ((bp->b_flags & B_CLUSTER) == 0) {
 232                         vfs_busy_pages(bp, 0);
 233                 }
 234                 bp->b_flags &= ~B_INVAL;
 235                 bp->b_ioflags &= ~BIO_ERROR;
 236                 if ((bp->b_flags & B_ASYNC) || bp->b_iodone != NULL)
 237                         BUF_KERNPROC(bp);
 238                 bp->b_iooffset = dbtob(bp->b_blkno);
 239                 error = VOP_STRATEGY(vp, bp);
 240                 curproc->p_stats->p_ru.ru_inblock++;
 241                 if (error)
 242                         return (error);
 243         }
 244
 245         /*
 246          * If we have been doing sequential I/O, then do some read-ahead.
 247          */
 248         while (lblkno < (origblkno + maxra)) {
 249                 error = VOP_BMAP(vp, lblkno, NULL, &blkno, &ncontig, NULL);
 250                 if (error)
 251                         break;
 252
 253                 if (blkno == -1)
 254                         break;
 255
 256                 /*
 257                  * We could throttle ncontig here by maxra but we might as
 258                  * well read the data if it is contiguous.  We're throttled
 259                  * by racluster anyway.
 260                  */
 261                 if (ncontig) {
 262                         ncontig = min(ncontig + 1, racluster);
 263                         rbp = cluster_rbuild(vp, filesize, lblkno, blkno,
 264                                 size, ncontig, NULL);
 265                         lblkno += (rbp->b_bufsize / size);
 266                         if (rbp->b_flags & B_DELWRI) {
 267                                 bqrelse(rbp);
 268                                 continue;
 269                         }
 270                 } else {
 271                         rbp = getblk(vp, lblkno, size, 0, 0, 0);
 272                         lblkno += 1;
 273                         if (rbp->b_flags & B_DELWRI) {
 274                                 bqrelse(rbp);
 275                                 continue;
 276                         }
 277                         rbp->b_flags |= B_ASYNC | B_RAM;
 278                         rbp->b_iocmd = BIO_READ;
 279                         rbp->b_blkno = blkno;
 280                 }
 281                 if (rbp->b_flags & B_CACHE) {
 282                         rbp->b_flags &= ~B_ASYNC;
 283                         bqrelse(rbp);
 284                         continue;
 285                 }
 286                 if ((rbp->b_flags & B_CLUSTER) == 0) {
 287                         vfs_busy_pages(rbp, 0);
 288                 }
 289                 rbp->b_flags &= ~B_INVAL;
 290                 rbp->b_ioflags &= ~BIO_ERROR;
 291                 if ((rbp->b_flags & B_ASYNC) || rbp->b_iodone != NULL)
 292                         BUF_KERNPROC(rbp);
 293                 rbp->b_iooffset = dbtob(rbp->b_blkno);
 294                 (void) VOP_STRATEGY(vp, rbp);
 295                 curproc->p_stats->p_ru.ru_inblock++;
 296         }
 297
 298         if (reqbp)
 299                 return (bufwait(reqbp));
 300         else
 301                 return (error);
 302 }
 303
 304 /*
 305  * If blocks are contiguous on disk, use this to provide clustered
 306  * read ahead.  We will read as many blocks as possible sequentially
 307  * and then parcel them up into logical blocks in the buffer hash table.
 308  */
 309 static struct buf *
 310 cluster_rbuild(vp, filesize, lbn, blkno, size, run, fbp)
 311         struct vnode *vp;
 312         u_quad_t filesize;
 313         daddr_t lbn;
 314         daddr_t blkno;
 315         long size;
 316         int run;
 317         struct buf *fbp;
 318 {
 319         struct buf *bp, *tbp;
 320         daddr_t bn;
 321         int i, inc, j;
 322
 323         GIANT_REQUIRED;
 324
 325         KASSERT(size == vp->v_mount->mnt_stat.f_iosize,
 326             ("cluster_rbuild: size %ld != filesize %jd\n",
 327             size, (intmax_t)vp->v_mount->mnt_stat.f_iosize));
 328
 329         /*
 330          * avoid a division
 331          */
 332         while ((u_quad_t) size * (lbn + run) > filesize) {
 333                 --run;
 334         }
 335
 336         if (fbp) {
 337                 tbp = fbp;
 338                 tbp->b_iocmd = BIO_READ;
 339         } else {
 340                 tbp = getblk(vp, lbn, size, 0, 0, 0);
 341                 if (tbp->b_flags & B_CACHE)
 342                         return tbp;
 343                 tbp->b_flags |= B_ASYNC | B_RAM;
 344                 tbp->b_iocmd = BIO_READ;
 345         }
 346
 347         tbp->b_blkno = blkno;
 348         if( (tbp->b_flags & B_MALLOC) ||
 349                 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1) )
 350                 return tbp;
 351
 352         bp = trypbuf(&cluster_pbuf_freecnt);
 353         if (bp == 0)
 354                 return tbp;
 355
 356         /*
 357          * We are synthesizing a buffer out of vm_page_t's, but
 358          * if the block size is not page aligned then the starting
 359          * address may not be either.  Inherit the b_data offset
 360          * from the original buffer.
 361          */
 362         bp->b_data = (char *)((vm_offset_t)bp->b_data |
 363             ((vm_offset_t)tbp->b_data & PAGE_MASK));
 364         bp->b_flags = B_ASYNC | B_CLUSTER | B_VMIO;
 365         bp->b_iocmd = BIO_READ;
 366         bp->b_iodone = cluster_callback;
 367         bp->b_blkno = blkno;
 368         bp->b_lblkno = lbn;
 369         bp->b_offset = tbp->b_offset;
 370         KASSERT(bp->b_offset != NOOFFSET, ("cluster_rbuild: no buffer offset"));
 371         pbgetvp(vp, bp);
 372
 373         TAILQ_INIT(&bp->b_cluster.cluster_head);
 374
 375         bp->b_bcount = 0;
 376         bp->b_bufsize = 0;
 377         bp->b_npages = 0;
 378
 379         inc = btodb(size);
 380         for (bn = blkno, i = 0; i < run; ++i, bn += inc) {
 381                 if (i != 0) {
 382                         if ((bp->b_npages * PAGE_SIZE) +
 383                             round_page(size) > vp->v_mount->mnt_iosize_max) {
 384                                 break;
 385                         }
 386
 387                         tbp = getblk(vp, lbn + i, size, 0, 0, GB_LOCK_NOWAIT);
 388
 389                         /* Don't wait around for locked bufs. */
 390                         if (tbp == NULL)
 391                                 break;
 392
 393                         /*
 394                          * Stop scanning if the buffer is fully valid
 395                          * (marked B_CACHE), or locked (may be doing a
 396                          * background write), or if the buffer is not
 397                          * VMIO backed.  The clustering code can only deal
 398                          * with VMIO-backed buffers.
 399                          */
 400                         VI_LOCK(bp->b_vp);
 401                         if ((tbp->b_vflags & BV_BKGRDINPROG) ||
 402                             (tbp->b_flags & B_CACHE) ||
 403                             (tbp->b_flags & B_VMIO) == 0) {
 404                                 VI_UNLOCK(bp->b_vp);
 405                                 bqrelse(tbp);
 406                                 break;
 407                         }
 408                         VI_UNLOCK(bp->b_vp);
 409
 410                         /*
 411                          * The buffer must be completely invalid in order to
 412                          * take part in the cluster.  If it is partially valid
 413                          * then we stop.
 414                          */
 415                         VM_OBJECT_LOCK(tbp->b_object);
 416                         for (j = 0;j < tbp->b_npages; j++) {
 417                                 VM_OBJECT_LOCK_ASSERT(tbp->b_pages[j]->object,
 418                                     MA_OWNED);
 419                                 if (tbp->b_pages[j]->valid)
 420                                         break;
 421                         }
 422                         VM_OBJECT_UNLOCK(tbp->b_object);
 423                         if (j != tbp->b_npages) {
 424                                 bqrelse(tbp);
 425                                 break;
 426                         }
 427
 428                         /*
 429                          * Set a read-ahead mark as appropriate
 430                          */
 431                         if ((fbp && (i == 1)) || (i == (run - 1)))
 432                                 tbp->b_flags |= B_RAM;
 433
 434                         /*
 435                          * Set the buffer up for an async read (XXX should
 436                          * we do this only if we do not wind up brelse()ing?).
 437                          * Set the block number if it isn't set, otherwise
 438                          * if it is make sure it matches the block number we
 439                          * expect.
 440                          */
 441                         tbp->b_flags |= B_ASYNC;
 442                         tbp->b_iocmd = BIO_READ;
 443                         if (tbp->b_blkno == tbp->b_lblkno) {
 444                                 tbp->b_blkno = bn;
 445                         } else if (tbp->b_blkno != bn) {
 446                                 brelse(tbp);
 447                                 break;
 448                         }
 449                 }
 450                 /*
 451                  * XXX fbp from caller may not be B_ASYNC, but we are going
 452                  * to biodone() it in cluster_callback() anyway
 453                  */
 454                 BUF_KERNPROC(tbp);
 455                 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head,
 456                         tbp, b_cluster.cluster_entry);
 457                 VM_OBJECT_LOCK(tbp->b_object);
 458                 vm_page_lock_queues();
 459                 for (j = 0; j < tbp->b_npages; j += 1) {
 460                         vm_page_t m;
 461                         m = tbp->b_pages[j];
 462                         vm_page_io_start(m);
 463                         vm_object_pip_add(m->object, 1);
 464                         if ((bp->b_npages == 0) ||
 465                                 (bp->b_pages[bp->b_npages-1] != m)) {
 466                                 bp->b_pages[bp->b_npages] = m;
 467                                 bp->b_npages++;
 468                         }
 469                         if ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL)
 470                                 tbp->b_pages[j] = bogus_page;
 471                 }
 472                 vm_page_unlock_queues();
 473                 VM_OBJECT_UNLOCK(tbp->b_object);
 474                 /*
 475                  * XXX shouldn't this be += size for both, like in
 476                  * cluster_wbuild()?
 477                  *
 478                  * Don't inherit tbp->b_bufsize as it may be larger due to
 479                  * a non-page-aligned size.  Instead just aggregate using
 480                  * 'size'.
 481                  */
 482                 if (tbp->b_bcount != size)
 483                         printf("warning: tbp->b_bcount wrong %ld vs %ld\n", tbp->b_bcount, size);
 484                 if (tbp->b_bufsize != size)
 485                         printf("warning: tbp->b_bufsize wrong %ld vs %ld\n", tbp->b_bufsize, size);
 486                 bp->b_bcount += size;
 487                 bp->b_bufsize += size;
 488         }
 489
 490         /*
 491          * Fully valid pages in the cluster are already good and do not need
 492          * to be re-read from disk.  Replace the page with bogus_page
 493          */
 494         VM_OBJECT_LOCK(bp->b_object);
 495         for (j = 0; j < bp->b_npages; j++) {
 496                 VM_OBJECT_LOCK_ASSERT(bp->b_pages[j]->object, MA_OWNED);
 497                 if ((bp->b_pages[j]->valid & VM_PAGE_BITS_ALL) ==
 498                     VM_PAGE_BITS_ALL) {
 499                         bp->b_pages[j] = bogus_page;
 500                 }
 501         }
 502         VM_OBJECT_UNLOCK(bp->b_object);
 503         if (bp->b_bufsize > bp->b_kvasize)
 504                 panic("cluster_rbuild: b_bufsize(%ld) > b_kvasize(%d)\n",
 505                     bp->b_bufsize, bp->b_kvasize);
 506         bp->b_kvasize = bp->b_bufsize;
 507
 508         pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
 509                 (vm_page_t *)bp->b_pages, bp->b_npages);
 510         return (bp);
 511 }
 512
 513 /*
 514  * Cleanup after a clustered read or write.
 515  * This is complicated by the fact that any of the buffers might have
 516  * extra memory (if there were no empty buffer headers at allocbuf time)
 517  * that we will need to shift around.
 518  */
 519 void
 520 cluster_callback(bp)
 521         struct buf *bp;
 522 {
 523         struct buf *nbp, *tbp;
 524         int error = 0;
 525
 526         GIANT_REQUIRED;
 527
 528         /*
 529          * Must propogate errors to all the components.
 530          */
 531         if (bp->b_ioflags & BIO_ERROR)
 532                 error = bp->b_error;
 533
 534         pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages);
 535         /*
 536          * Move memory from the large cluster buffer into the component
 537          * buffers and mark IO as done on these.
 538          */
 539         for (tbp = TAILQ_FIRST(&bp->b_cluster.cluster_head);
 540                 tbp; tbp = nbp) {
 541                 nbp = TAILQ_NEXT(&tbp->b_cluster, cluster_entry);
 542                 if (error) {
 543                         tbp->b_ioflags |= BIO_ERROR;
 544                         tbp->b_error = error;
 545                 } else {
 546                         tbp->b_dirtyoff = tbp->b_dirtyend = 0;
 547                         tbp->b_flags &= ~B_INVAL;
 548                         tbp->b_ioflags &= ~BIO_ERROR;
 549                         /*
 550                          * XXX the bdwrite()/bqrelse() issued during
 551                          * cluster building clears B_RELBUF (see bqrelse()
 552                          * comment).  If direct I/O was specified, we have
 553                          * to restore it here to allow the buffer and VM
 554                          * to be freed.
 555                          */
 556                         if (tbp->b_flags & B_DIRECT)
 557                                 tbp->b_flags |= B_RELBUF;
 558                 }
 559                 bufdone(tbp);
 560         }
 561         relpbuf(bp, &cluster_pbuf_freecnt);
 562 }
 563
 564 /*
 565  *      cluster_wbuild_wb:
 566  *
 567  *      Implement modified write build for cluster.
 568  *
 569  *              write_behind = 0        write behind disabled
 570  *              write_behind = 1        write behind normal (default)
 571  *              write_behind = 2        write behind backed-off
 572  */
 573
 574 static __inline int
 575 cluster_wbuild_wb(struct vnode *vp, long size, daddr_t start_lbn, int len)
 576 {
 577         int r = 0;
 578
 579         switch(write_behind) {
 580         case 2:
 581                 if (start_lbn < len)
 582                         break;
 583                 start_lbn -= len;
 584                 /* FALLTHROUGH */
 585         case 1:
 586                 r = cluster_wbuild(vp, size, start_lbn, len);
 587                 /* FALLTHROUGH */
 588         default:
 589                 /* FALLTHROUGH */
 590                 break;
 591         }
 592         return(r);
 593 }
 594
 595 /*
 596  * Do clustered write for FFS.
 597  *
 598  * Three cases:
 599  *      1. Write is not sequential (write asynchronously)
 600  *      Write is sequential:
 601  *      2.      beginning of cluster - begin cluster
 602  *      3.      middle of a cluster - add to cluster
 603  *      4.      end of a cluster - asynchronously write cluster
 604  */
 605 void
 606 cluster_write(bp, filesize, seqcount)
 607         struct buf *bp;
 608         u_quad_t filesize;
 609         int seqcount;
 610 {
 611         struct vnode *vp;
 612         daddr_t lbn;
 613         int maxclen, cursize;
 614         int lblocksize;
 615         int async;
 616
 617         vp = bp->b_vp;
 618         if (vp->v_type == VREG) {
 619                 async = vp->v_mount->mnt_flag & MNT_ASYNC;
 620                 lblocksize = vp->v_mount->mnt_stat.f_iosize;
 621         } else {
 622                 async = 0;
 623                 lblocksize = bp->b_bufsize;
 624         }
 625         lbn = bp->b_lblkno;
 626         KASSERT(bp->b_offset != NOOFFSET, ("cluster_write: no buffer offset"));
 627
 628         /* Initialize vnode to beginning of file. */
 629         if (lbn == 0)
 630                 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0;
 631
 632         if (vp->v_clen == 0 || lbn != vp->v_lastw + 1 ||
 633             (bp->b_blkno != vp->v_lasta + btodb(lblocksize))) {
 634                 maxclen = vp->v_mount->mnt_iosize_max / lblocksize - 1;
 635                 if (vp->v_clen != 0) {
 636                         /*
 637                          * Next block is not sequential.
 638                          *
 639                          * If we are not writing at end of file, the process
 640                          * seeked to another point in the file since its last
 641                          * write, or we have reached our maximum cluster size,
 642                          * then push the previous cluster. Otherwise try
 643                          * reallocating to make it sequential.
 644                          *
 645                          * Change to algorithm: only push previous cluster if
 646                          * it was sequential from the point of view of the
 647                          * seqcount heuristic, otherwise leave the buffer
 648                          * intact so we can potentially optimize the I/O
 649                          * later on in the buf_daemon or update daemon
 650                          * flush.
 651                          */
 652                         cursize = vp->v_lastw - vp->v_cstart + 1;
 653                         if (((u_quad_t) bp->b_offset + lblocksize) != filesize ||
 654                             lbn != vp->v_lastw + 1 || vp->v_clen <= cursize) {
 655                                 if (!async && seqcount > 0) {
 656                                         cluster_wbuild_wb(vp, lblocksize,
 657                                                 vp->v_cstart, cursize);
 658                                 }
 659                         } else {
 660                                 struct buf **bpp, **endbp;
 661                                 struct cluster_save *buflist;
 662
 663                                 buflist = cluster_collectbufs(vp, bp);
 664                                 endbp = &buflist->bs_children
 665                                     [buflist->bs_nchildren - 1];
 666                                 if (VOP_REALLOCBLKS(vp, buflist)) {
 667                                         /*
 668                                          * Failed, push the previous cluster
 669                                          * if *really* writing sequentially
 670                                          * in the logical file (seqcount > 1),
 671                                          * otherwise delay it in the hopes that
 672                                          * the low level disk driver can
 673                                          * optimize the write ordering.
 674                                          */
 675                                         for (bpp = buflist->bs_children;
 676                                              bpp < endbp; bpp++)
 677                                                 brelse(*bpp);
 678                                         free(buflist, M_SEGMENT);
 679                                         if (seqcount > 1) {
 680                                                 cluster_wbuild_wb(vp,
 681                                                     lblocksize, vp->v_cstart,
 682                                                     cursize);
 683                                         }
 684                                 } else {
 685                                         /*
 686                                          * Succeeded, keep building cluster.
 687                                          */
 688                                         for (bpp = buflist->bs_children;
 689                                              bpp <= endbp; bpp++)
 690                                                 bdwrite(*bpp);
 691                                         free(buflist, M_SEGMENT);
 692                                         vp->v_lastw = lbn;
 693                                         vp->v_lasta = bp->b_blkno;
 694                                         return;
 695                                 }
 696                         }
 697                 }
 698                 /*
 699                  * Consider beginning a cluster. If at end of file, make
 700                  * cluster as large as possible, otherwise find size of
 701                  * existing cluster.
 702                  */
 703                 if ((vp->v_type == VREG) &&
 704                         ((u_quad_t) bp->b_offset + lblocksize) != filesize &&
 705                     (bp->b_blkno == bp->b_lblkno) &&
 706                     (VOP_BMAP(vp, lbn, NULL, &bp->b_blkno, &maxclen, NULL) ||
 707                      bp->b_blkno == -1)) {
 708                         bawrite(bp);
 709                         vp->v_clen = 0;
 710                         vp->v_lasta = bp->b_blkno;
 711                         vp->v_cstart = lbn + 1;
 712                         vp->v_lastw = lbn;
 713                         return;
 714                 }
 715                 vp->v_clen = maxclen;
 716                 if (!async && maxclen == 0) {   /* I/O not contiguous */
 717                         vp->v_cstart = lbn + 1;
 718                         bawrite(bp);
 719                 } else {        /* Wait for rest of cluster */
 720                         vp->v_cstart = lbn;
 721                         bdwrite(bp);
 722                 }
 723         } else if (lbn == vp->v_cstart + vp->v_clen) {
 724                 /*
 725                  * At end of cluster, write it out if seqcount tells us we
 726                  * are operating sequentially, otherwise let the buf or
 727                  * update daemon handle it.
 728                  */
 729                 bdwrite(bp);
 730                 if (seqcount > 1)
 731                         cluster_wbuild_wb(vp, lblocksize, vp->v_cstart, vp->v_clen + 1);
 732                 vp->v_clen = 0;
 733                 vp->v_cstart = lbn + 1;
 734         } else if (vm_page_count_severe()) {
 735                 /*
 736                  * We are low on memory, get it going NOW
 737                  */
 738                 bawrite(bp);
 739         } else {
 740                 /*
 741                  * In the middle of a cluster, so just delay the I/O for now.
 742                  */
 743                 bdwrite(bp);
 744         }
 745         vp->v_lastw = lbn;
 746         vp->v_lasta = bp->b_blkno;
 747 }
 748
 749
 750 /*
 751  * This is an awful lot like cluster_rbuild...wish they could be combined.
 752  * The last lbn argument is the current block on which I/O is being
 753  * performed.  Check to see that it doesn't fall in the middle of
 754  * the current block (if last_bp == NULL).
 755  */
 756 int
 757 cluster_wbuild(vp, size, start_lbn, len)
 758         struct vnode *vp;
 759         long size;
 760         daddr_t start_lbn;
 761         int len;
 762 {
 763         struct buf *bp, *tbp;
 764         int i, j, s;
 765         int totalwritten = 0;
 766         int dbsize = btodb(size);
 767
 768         GIANT_REQUIRED;
 769
 770         while (len > 0) {
 771                 s = splbio();
 772                 /*
 773                  * If the buffer is not delayed-write (i.e. dirty), or it
 774                  * is delayed-write but either locked or inval, it cannot
 775                  * partake in the clustered write.
 776                  */
 777                 VI_LOCK(vp);
 778                 if ((tbp = gbincore(vp, start_lbn)) == NULL ||
 779                     (tbp->b_vflags & BV_BKGRDINPROG)) {
 780                         VI_UNLOCK(vp);
 781                         ++start_lbn;
 782                         --len;
 783                         splx(s);
 784                         continue;
 785                 }
 786                 if (BUF_LOCK(tbp,
 787                     LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, VI_MTX(vp))) {
 788                         ++start_lbn;
 789                         --len;
 790                         splx(s);
 791                         continue;
 792                 }
 793                 if ((tbp->b_flags & (B_INVAL | B_DELWRI)) != B_DELWRI) {
 794                         BUF_UNLOCK(tbp);
 795                         ++start_lbn;
 796                         --len;
 797                         splx(s);
 798                         continue;
 799                 }
 800                 bremfree(tbp);
 801                 tbp->b_flags &= ~B_DONE;
 802                 splx(s);
 803
 804                 /*
 805                  * Extra memory in the buffer, punt on this buffer.
 806                  * XXX we could handle this in most cases, but we would
 807                  * have to push the extra memory down to after our max
 808                  * possible cluster size and then potentially pull it back
 809                  * up if the cluster was terminated prematurely--too much
 810                  * hassle.
 811                  */
 812                 if (((tbp->b_flags & (B_CLUSTEROK | B_MALLOC | B_VMIO)) !=
 813                      (B_CLUSTEROK | B_VMIO)) ||
 814                   (tbp->b_bcount != tbp->b_bufsize) ||
 815                   (tbp->b_bcount != size) ||
 816                   (len == 1) ||
 817                   ((bp = getpbuf(&cluster_pbuf_freecnt)) == NULL)) {
 818                         totalwritten += tbp->b_bufsize;
 819                         bawrite(tbp);
 820                         ++start_lbn;
 821                         --len;
 822                         continue;
 823                 }
 824
 825                 /*
 826                  * We got a pbuf to make the cluster in.
 827                  * so initialise it.
 828                  */
 829                 TAILQ_INIT(&bp->b_cluster.cluster_head);
 830                 bp->b_bcount = 0;
 831                 bp->b_magic = tbp->b_magic;
 832                 bp->b_op = tbp->b_op;
 833                 bp->b_bufsize = 0;
 834                 bp->b_npages = 0;
 835                 if (tbp->b_wcred != NOCRED)
 836                         bp->b_wcred = crhold(tbp->b_wcred);
 837
 838                 bp->b_blkno = tbp->b_blkno;
 839                 bp->b_lblkno = tbp->b_lblkno;
 840                 bp->b_offset = tbp->b_offset;
 841
 842                 /*
 843                  * We are synthesizing a buffer out of vm_page_t's, but
 844                  * if the block size is not page aligned then the starting
 845                  * address may not be either.  Inherit the b_data offset
 846                  * from the original buffer.
 847                  */
 848                 bp->b_data = (char *)((vm_offset_t)bp->b_data |
 849                     ((vm_offset_t)tbp->b_data & PAGE_MASK));
 850                 bp->b_flags |= B_CLUSTER |
 851                                 (tbp->b_flags & (B_VMIO | B_NEEDCOMMIT));
 852                 bp->b_iodone = cluster_callback;
 853                 pbgetvp(vp, bp);
 854                 /*
 855                  * From this location in the file, scan forward to see
 856                  * if there are buffers with adjacent data that need to
 857                  * be written as well.
 858                  */
 859                 for (i = 0; i < len; ++i, ++start_lbn) {
 860                         if (i != 0) { /* If not the first buffer */
 861                                 s = splbio();
 862                                 /*
 863                                  * If the adjacent data is not even in core it
 864                                  * can't need to be written.
 865                                  */
 866                                 VI_LOCK(vp);
 867                                 if ((tbp = gbincore(vp, start_lbn)) == NULL ||
 868                                     (tbp->b_vflags & BV_BKGRDINPROG)) {
 869                                         VI_UNLOCK(vp);
 870                                         splx(s);
 871                                         break;
 872                                 }
 873
 874                                 /*
 875                                  * If it IS in core, but has different
 876                                  * characteristics, or is locked (which
 877                                  * means it could be undergoing a background
 878                                  * I/O or be in a weird state), then don't
 879                                  * cluster with it.
 880                                  */
 881                                 if (BUF_LOCK(tbp,
 882                                     LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK,
 883                                     VI_MTX(vp))) {
 884                                         splx(s);
 885                                         break;
 886                                 }
 887
 888                                 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK |
 889                                     B_INVAL | B_DELWRI | B_NEEDCOMMIT))
 890                                     != (B_DELWRI | B_CLUSTEROK |
 891                                     (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) ||
 892                                     tbp->b_wcred != bp->b_wcred) {
 893                                         BUF_UNLOCK(tbp);
 894                                         splx(s);
 895                                         break;
 896                                 }
 897
 898                                 /*
 899                                  * Check that the combined cluster
 900                                  * would make sense with regard to pages
 901                                  * and would not be too large
 902                                  */
 903                                 if ((tbp->b_bcount != size) ||
 904                                   ((bp->b_blkno + (dbsize * i)) !=
 905                                     tbp->b_blkno) ||
 906                                   ((tbp->b_npages + bp->b_npages) >
 907                                     (vp->v_mount->mnt_iosize_max / PAGE_SIZE))) {
 908                                         BUF_UNLOCK(tbp);
 909                                         splx(s);
 910                                         break;
 911                                 }
 912                                 /*
 913                                  * Ok, it's passed all the tests,
 914                                  * so remove it from the free list
 915                                  * and mark it busy. We will use it.
 916                                  */
 917                                 bremfree(tbp);
 918                                 tbp->b_flags &= ~B_DONE;
 919                                 splx(s);
 920                         } /* end of code for non-first buffers only */
 921                         /* check for latent dependencies to be handled */
 922                         if ((LIST_FIRST(&tbp->b_dep)) != NULL) {
 923                                 tbp->b_iocmd = BIO_WRITE;
 924                                 buf_start(tbp);
 925                         }
 926                         /*
 927                          * If the IO is via the VM then we do some
 928                          * special VM hackery (yuck).  Since the buffer's
 929                          * block size may not be page-aligned it is possible
 930                          * for a page to be shared between two buffers.  We
 931                          * have to get rid of the duplication when building
 932                          * the cluster.
 933                          */
 934                         if (tbp->b_flags & B_VMIO) {
 935                                 vm_page_t m;
 936
 937                                 if (i != 0) { /* if not first buffer */
 938                                         for (j = 0; j < tbp->b_npages; j += 1) {
 939                                                 m = tbp->b_pages[j];
 940                                                 if (m->flags & PG_BUSY) {
 941                                                         bqrelse(tbp);
 942                                                         goto finishcluster;
 943                                                 }
 944                                         }
 945                                 }
 946                                 if (tbp->b_object != NULL)
 947                                         VM_OBJECT_LOCK(tbp->b_object);
 948                                 vm_page_lock_queues();
 949                                 for (j = 0; j < tbp->b_npages; j += 1) {
 950                                         m = tbp->b_pages[j];
 951                                         vm_page_io_start(m);
 952                                         vm_object_pip_add(m->object, 1);
 953                                         if ((bp->b_npages == 0) ||
 954                                           (bp->b_pages[bp->b_npages - 1] != m)) {
 955                                                 bp->b_pages[bp->b_npages] = m;
 956                                                 bp->b_npages++;
 957                                         }
 958                                 }
 959                                 vm_page_unlock_queues();
 960                                 if (tbp->b_object != NULL)
 961                                         VM_OBJECT_UNLOCK(tbp->b_object);
 962                         }
 963                         bp->b_bcount += size;
 964                         bp->b_bufsize += size;
 965
 966                         s = splbio();
 967                         bundirty(tbp);
 968                         tbp->b_flags &= ~B_DONE;
 969                         tbp->b_ioflags &= ~BIO_ERROR;
 970                         tbp->b_flags |= B_ASYNC;
 971                         tbp->b_iocmd = BIO_WRITE;
 972                         reassignbuf(tbp);               /* put on clean list */
 973                         VI_LOCK(tbp->b_vp);
 974                         ++tbp->b_vp->v_numoutput;
 975                         VI_UNLOCK(tbp->b_vp);
 976                         splx(s);
 977                         BUF_KERNPROC(tbp);
 978                         TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head,
 979                                 tbp, b_cluster.cluster_entry);
 980                 }
 981         finishcluster:
 982                 pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
 983                         (vm_page_t *) bp->b_pages, bp->b_npages);
 984                 if (bp->b_bufsize > bp->b_kvasize)
 985                         panic(
 986                             "cluster_wbuild: b_bufsize(%ld) > b_kvasize(%d)\n",
 987                             bp->b_bufsize, bp->b_kvasize);
 988                 bp->b_kvasize = bp->b_bufsize;
 989                 totalwritten += bp->b_bufsize;
 990                 bp->b_dirtyoff = 0;
 991                 bp->b_dirtyend = bp->b_bufsize;
 992                 bawrite(bp);
 993
 994                 len -= i;
 995         }
 996         return totalwritten;
 997 }
 998
 999 /*
1000  * Collect together all the buffers in a cluster.
1001  * Plus add one additional buffer.
1002  */
1003 static struct cluster_save *
1004 cluster_collectbufs(vp, last_bp)
1005         struct vnode *vp;
1006         struct buf *last_bp;
1007 {
1008         struct cluster_save *buflist;
1009         struct buf *bp;
1010         daddr_t lbn;
1011         int i, len;
1012
1013         len = vp->v_lastw - vp->v_cstart + 1;
1014         buflist = malloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist),
1015             M_SEGMENT, M_WAITOK);
1016         buflist->bs_nchildren = 0;
1017         buflist->bs_children = (struct buf **) (buflist + 1);
1018         for (lbn = vp->v_cstart, i = 0; i < len; lbn++, i++) {
1019                 (void) bread(vp, lbn, last_bp->b_bcount, NOCRED, &bp);
1020                 buflist->bs_children[i] = bp;
1021                 if (bp->b_blkno == bp->b_lblkno)
1022                         VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno,
1023                                 NULL, NULL);
1024         }
1025         buflist->bs_children[i] = bp = last_bp;
1026         if (bp->b_blkno == bp->b_lblkno)
1027                 VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_blkno,
1028                         NULL, NULL);
1029         buflist->bs_nchildren = i + 1;
1030         return (buflist);
1031 }