sys/kern/vfs_cluster.c

   1 /*-
   2  * Copyright (c) 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  * Modifications/enhancements:
   5  *      Copyright (c) 1995 John S. Dyson.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. Neither the name of the University nor the names of its contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  *
  31  *      @(#)vfs_cluster.c       8.7 (Berkeley) 2/13/94
  32  */
  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/racct.h>
  49 #include <sys/resourcevar.h>
  50 #include <sys/rwlock.h>
  51 #include <sys/vmmeter.h>
  52 #include <vm/vm.h>
  53 #include <vm/vm_object.h>
  54 #include <vm/vm_page.h>
  55 #include <sys/sysctl.h>
  56
  57 #if defined(CLUSTERDEBUG)
  58 static int      rcluster= 0;
  59 SYSCTL_INT(_debug, OID_AUTO, rcluster, CTLFLAG_RW, &rcluster, 0,
  60     "Debug VFS clustering code");
  61 #endif
  62
  63 static MALLOC_DEFINE(M_SEGMENT, "cl_savebuf", "cluster_save buffer");
  64
  65 static struct cluster_save *cluster_collectbufs(struct vnode *vp,
  66             struct buf *last_bp, int gbflags);
  67 static struct buf *cluster_rbuild(struct vnode *vp, u_quad_t filesize,
  68             daddr_t lbn, daddr_t blkno, long size, int run, int gbflags,
  69             struct buf *fbp);
  70 static void cluster_callback(struct buf *);
  71
  72 static int write_behind = 1;
  73 SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0,
  74     "Cluster write-behind; 0: disable, 1: enable, 2: backed off");
  75
  76 static int read_max = 64;
  77 SYSCTL_INT(_vfs, OID_AUTO, read_max, CTLFLAG_RW, &read_max, 0,
  78     "Cluster read-ahead max block count");
  79
  80 static int read_min = 1;
  81 SYSCTL_INT(_vfs, OID_AUTO, read_min, CTLFLAG_RW, &read_min, 0,
  82     "Cluster read min block count");
  83
  84 /*
  85  * Read data to a buf, including read-ahead if we find this to be beneficial.
  86  * cluster_read replaces bread.
  87  */
  88 int
  89 cluster_read(struct vnode *vp, u_quad_t filesize, daddr_t lblkno, long size,
  90     struct ucred *cred, long totread, int seqcount, int gbflags,
  91     struct buf **bpp)
  92 {
  93         struct buf *bp, *rbp, *reqbp;
  94         struct bufobj *bo;
  95         daddr_t blkno, origblkno;
  96         int maxra, racluster;
  97         int error, ncontig;
  98         int i;
  99
 100         error = 0;
 101         bo = &vp->v_bufobj;
 102         if (!unmapped_buf_allowed)
 103                 gbflags &= ~GB_UNMAPPED;
 104
 105         /*
 106          * Try to limit the amount of read-ahead by a few
 107          * ad-hoc parameters.  This needs work!!!
 108          */
 109         racluster = vp->v_mount->mnt_iosize_max / size;
 110         maxra = seqcount;
 111         maxra = min(read_max, maxra);
 112         maxra = min(nbuf/8, maxra);
 113         if (((u_quad_t)(lblkno + maxra + 1) * size) > filesize)
 114                 maxra = (filesize / size) - lblkno;
 115
 116         /*
 117          * get the requested block
 118          */
 119         *bpp = reqbp = bp = getblk(vp, lblkno, size, 0, 0, gbflags);
 120         if (bp == NULL)
 121                 return (EBUSY);
 122         origblkno = lblkno;
 123
 124         /*
 125          * if it is in the cache, then check to see if the reads have been
 126          * sequential.  If they have, then try some read-ahead, otherwise
 127          * back-off on prospective read-aheads.
 128          */
 129         if (bp->b_flags & B_CACHE) {
 130                 if (!seqcount) {
 131                         return 0;
 132                 } else if ((bp->b_flags & B_RAM) == 0) {
 133                         return 0;
 134                 } else {
 135                         bp->b_flags &= ~B_RAM;
 136                         BO_RLOCK(bo);
 137                         for (i = 1; i < maxra; i++) {
 138                                 /*
 139                                  * Stop if the buffer does not exist or it
 140                                  * is invalid (about to go away?)
 141                                  */
 142                                 rbp = gbincore(&vp->v_bufobj, lblkno+i);
 143                                 if (rbp == NULL || (rbp->b_flags & B_INVAL))
 144                                         break;
 145
 146                                 /*
 147                                  * Set another read-ahead mark so we know
 148                                  * to check again. (If we can lock the
 149                                  * buffer without waiting)
 150                                  */
 151                                 if ((((i % racluster) == (racluster - 1)) ||
 152                                     (i == (maxra - 1)))
 153                                     && (0 == BUF_LOCK(rbp,
 154                                         LK_EXCLUSIVE | LK_NOWAIT, NULL))) {
 155                                         rbp->b_flags |= B_RAM;
 156                                         BUF_UNLOCK(rbp);
 157                                 }
 158                         }
 159                         BO_RUNLOCK(bo);
 160                         if (i >= maxra) {
 161                                 return 0;
 162                         }
 163                         lblkno += i;
 164                 }
 165                 reqbp = bp = NULL;
 166         /*
 167          * If it isn't in the cache, then get a chunk from
 168          * disk if sequential, otherwise just get the block.
 169          */
 170         } else {
 171                 off_t firstread = bp->b_offset;
 172                 int nblks;
 173                 long minread;
 174
 175                 KASSERT(bp->b_offset != NOOFFSET,
 176                     ("cluster_read: no buffer offset"));
 177
 178                 ncontig = 0;
 179
 180                 /*
 181                  * Adjust totread if needed
 182                  */
 183                 minread = read_min * size;
 184                 if (minread > totread)
 185                         totread = minread;
 186
 187                 /*
 188                  * Compute the total number of blocks that we should read
 189                  * synchronously.
 190                  */
 191                 if (firstread + totread > filesize)
 192                         totread = filesize - firstread;
 193                 nblks = howmany(totread, size);
 194                 if (nblks > racluster)
 195                         nblks = racluster;
 196
 197                 /*
 198                  * Now compute the number of contiguous blocks.
 199                  */
 200                 if (nblks > 1) {
 201                         error = VOP_BMAP(vp, lblkno, NULL,
 202                                 &blkno, &ncontig, NULL);
 203                         /*
 204                          * If this failed to map just do the original block.
 205                          */
 206                         if (error || blkno == -1)
 207                                 ncontig = 0;
 208                 }
 209
 210                 /*
 211                  * If we have contiguous data available do a cluster
 212                  * otherwise just read the requested block.
 213                  */
 214                 if (ncontig) {
 215                         /* Account for our first block. */
 216                         ncontig = min(ncontig + 1, nblks);
 217                         if (ncontig < nblks)
 218                                 nblks = ncontig;
 219                         bp = cluster_rbuild(vp, filesize, lblkno,
 220                             blkno, size, nblks, gbflags, bp);
 221                         lblkno += (bp->b_bufsize / size);
 222                 } else {
 223                         bp->b_flags |= B_RAM;
 224                         bp->b_iocmd = BIO_READ;
 225                         lblkno += 1;
 226                 }
 227         }
 228
 229         /*
 230          * handle the synchronous read so that it is available ASAP.
 231          */
 232         if (bp) {
 233                 if ((bp->b_flags & B_CLUSTER) == 0) {
 234                         vfs_busy_pages(bp, 0);
 235                 }
 236                 bp->b_flags &= ~B_INVAL;
 237                 bp->b_ioflags &= ~BIO_ERROR;
 238                 if ((bp->b_flags & B_ASYNC) || bp->b_iodone != NULL)
 239                         BUF_KERNPROC(bp);
 240                 bp->b_iooffset = dbtob(bp->b_blkno);
 241                 bstrategy(bp);
 242 #ifdef RACCT
 243                 if (racct_enable) {
 244                         PROC_LOCK(curproc);
 245                         racct_add_buf(curproc, bp, 0);
 246                         PROC_UNLOCK(curproc);
 247                 }
 248 #endif /* RACCT */
 249                 curthread->td_ru.ru_inblock++;
 250         }
 251
 252         /*
 253          * If we have been doing sequential I/O, then do some read-ahead.
 254          */
 255         while (lblkno < (origblkno + maxra)) {
 256                 error = VOP_BMAP(vp, lblkno, NULL, &blkno, &ncontig, NULL);
 257                 if (error)
 258                         break;
 259
 260                 if (blkno == -1)
 261                         break;
 262
 263                 /*
 264                  * We could throttle ncontig here by maxra but we might as
 265                  * well read the data if it is contiguous.  We're throttled
 266                  * by racluster anyway.
 267                  */
 268                 if (ncontig) {
 269                         ncontig = min(ncontig + 1, racluster);
 270                         rbp = cluster_rbuild(vp, filesize, lblkno, blkno,
 271                             size, ncontig, gbflags, NULL);
 272                         lblkno += (rbp->b_bufsize / size);
 273                         if (rbp->b_flags & B_DELWRI) {
 274                                 bqrelse(rbp);
 275                                 continue;
 276                         }
 277                 } else {
 278                         rbp = getblk(vp, lblkno, size, 0, 0, gbflags);
 279                         lblkno += 1;
 280                         if (rbp->b_flags & B_DELWRI) {
 281                                 bqrelse(rbp);
 282                                 continue;
 283                         }
 284                         rbp->b_flags |= B_ASYNC | B_RAM;
 285                         rbp->b_iocmd = BIO_READ;
 286                         rbp->b_blkno = blkno;
 287                 }
 288                 if (rbp->b_flags & B_CACHE) {
 289                         rbp->b_flags &= ~B_ASYNC;
 290                         bqrelse(rbp);
 291                         continue;
 292                 }
 293                 if ((rbp->b_flags & B_CLUSTER) == 0) {
 294                         vfs_busy_pages(rbp, 0);
 295                 }
 296                 rbp->b_flags &= ~B_INVAL;
 297                 rbp->b_ioflags &= ~BIO_ERROR;
 298                 if ((rbp->b_flags & B_ASYNC) || rbp->b_iodone != NULL)
 299                         BUF_KERNPROC(rbp);
 300                 rbp->b_iooffset = dbtob(rbp->b_blkno);
 301                 bstrategy(rbp);
 302 #ifdef RACCT
 303                 if (racct_enable) {
 304                         PROC_LOCK(curproc);
 305                         racct_add_buf(curproc, rbp, 0);
 306                         PROC_UNLOCK(curproc);
 307                 }
 308 #endif /* RACCT */
 309                 curthread->td_ru.ru_inblock++;
 310         }
 311
 312         if (reqbp) {
 313                 /*
 314                  * Like bread, always brelse() the buffer when
 315                  * returning an error.
 316                  */
 317                 error = bufwait(reqbp);
 318                 if (error != 0) {
 319                         brelse(reqbp);
 320                         *bpp = NULL;
 321                 }
 322         }
 323         return (error);
 324 }
 325
 326 /*
 327  * If blocks are contiguous on disk, use this to provide clustered
 328  * read ahead.  We will read as many blocks as possible sequentially
 329  * and then parcel them up into logical blocks in the buffer hash table.
 330  */
 331 static struct buf *
 332 cluster_rbuild(struct vnode *vp, u_quad_t filesize, daddr_t lbn,
 333     daddr_t blkno, long size, int run, int gbflags, struct buf *fbp)
 334 {
 335         struct buf *bp, *tbp;
 336         daddr_t bn;
 337         off_t off;
 338         long tinc, tsize;
 339         int i, inc, j, k, toff;
 340
 341         KASSERT(size == vp->v_mount->mnt_stat.f_iosize,
 342             ("cluster_rbuild: size %ld != f_iosize %jd\n",
 343             size, (intmax_t)vp->v_mount->mnt_stat.f_iosize));
 344
 345         /*
 346          * avoid a division
 347          */
 348         while ((u_quad_t) size * (lbn + run) > filesize) {
 349                 --run;
 350         }
 351
 352         if (fbp) {
 353                 tbp = fbp;
 354                 tbp->b_iocmd = BIO_READ;
 355         } else {
 356                 tbp = getblk(vp, lbn, size, 0, 0, gbflags);
 357                 if (tbp->b_flags & B_CACHE)
 358                         return tbp;
 359                 tbp->b_flags |= B_ASYNC | B_RAM;
 360                 tbp->b_iocmd = BIO_READ;
 361         }
 362         tbp->b_blkno = blkno;
 363         if( (tbp->b_flags & B_MALLOC) ||
 364                 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1) )
 365                 return tbp;
 366
 367         bp = trypbuf(&cluster_pbuf_freecnt);
 368         if (bp == NULL)
 369                 return tbp;
 370
 371         /*
 372          * We are synthesizing a buffer out of vm_page_t's, but
 373          * if the block size is not page aligned then the starting
 374          * address may not be either.  Inherit the b_data offset
 375          * from the original buffer.
 376          */
 377         bp->b_flags = B_ASYNC | B_CLUSTER | B_VMIO;
 378         if ((gbflags & GB_UNMAPPED) != 0) {
 379                 bp->b_data = unmapped_buf;
 380         } else {
 381                 bp->b_data = (char *)((vm_offset_t)bp->b_data |
 382                     ((vm_offset_t)tbp->b_data & PAGE_MASK));
 383         }
 384         bp->b_iocmd = BIO_READ;
 385         bp->b_iodone = cluster_callback;
 386         bp->b_blkno = blkno;
 387         bp->b_lblkno = lbn;
 388         bp->b_offset = tbp->b_offset;
 389         KASSERT(bp->b_offset != NOOFFSET, ("cluster_rbuild: no buffer offset"));
 390         pbgetvp(vp, bp);
 391
 392         TAILQ_INIT(&bp->b_cluster.cluster_head);
 393
 394         bp->b_bcount = 0;
 395         bp->b_bufsize = 0;
 396         bp->b_npages = 0;
 397
 398         inc = btodb(size);
 399         for (bn = blkno, i = 0; i < run; ++i, bn += inc) {
 400                 if (i == 0) {
 401                         VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object);
 402                         vfs_drain_busy_pages(tbp);
 403                         vm_object_pip_add(tbp->b_bufobj->bo_object,
 404                             tbp->b_npages);
 405                         for (k = 0; k < tbp->b_npages; k++)
 406                                 vm_page_sbusy(tbp->b_pages[k]);
 407                         VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object);
 408                 } else {
 409                         if ((bp->b_npages * PAGE_SIZE) +
 410                             round_page(size) > vp->v_mount->mnt_iosize_max) {
 411                                 break;
 412                         }
 413
 414                         tbp = getblk(vp, lbn + i, size, 0, 0, GB_LOCK_NOWAIT |
 415                             (gbflags & GB_UNMAPPED));
 416
 417                         /* Don't wait around for locked bufs. */
 418                         if (tbp == NULL)
 419                                 break;
 420
 421                         /*
 422                          * Stop scanning if the buffer is fully valid
 423                          * (marked B_CACHE), or locked (may be doing a
 424                          * background write), or if the buffer is not
 425                          * VMIO backed.  The clustering code can only deal
 426                          * with VMIO-backed buffers.  The bo lock is not
 427                          * required for the BKGRDINPROG check since it
 428                          * can not be set without the buf lock.
 429                          */
 430                         if ((tbp->b_vflags & BV_BKGRDINPROG) ||
 431                             (tbp->b_flags & B_CACHE) ||
 432                             (tbp->b_flags & B_VMIO) == 0) {
 433                                 bqrelse(tbp);
 434                                 break;
 435                         }
 436
 437                         /*
 438                          * The buffer must be completely invalid in order to
 439                          * take part in the cluster.  If it is partially valid
 440                          * then we stop.
 441                          */
 442                         off = tbp->b_offset;
 443                         tsize = size;
 444                         VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object);
 445                         for (j = 0; tsize > 0; j++) {
 446                                 toff = off & PAGE_MASK;
 447                                 tinc = tsize;
 448                                 if (toff + tinc > PAGE_SIZE)
 449                                         tinc = PAGE_SIZE - toff;
 450                                 VM_OBJECT_ASSERT_WLOCKED(tbp->b_pages[j]->object);
 451                                 if ((tbp->b_pages[j]->valid &
 452                                     vm_page_bits(toff, tinc)) != 0)
 453                                         break;
 454                                 if (vm_page_xbusied(tbp->b_pages[j]))
 455                                         break;
 456                                 vm_object_pip_add(tbp->b_bufobj->bo_object, 1);
 457                                 vm_page_sbusy(tbp->b_pages[j]);
 458                                 off += tinc;
 459                                 tsize -= tinc;
 460                         }
 461                         if (tsize > 0) {
 462 clean_sbusy:
 463                                 vm_object_pip_add(tbp->b_bufobj->bo_object, -j);
 464                                 for (k = 0; k < j; k++)
 465                                         vm_page_sunbusy(tbp->b_pages[k]);
 466                                 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object);
 467                                 bqrelse(tbp);
 468                                 break;
 469                         }
 470                         VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object);
 471
 472                         /*
 473                          * Set a read-ahead mark as appropriate
 474                          */
 475                         if ((fbp && (i == 1)) || (i == (run - 1)))
 476                                 tbp->b_flags |= B_RAM;
 477
 478                         /*
 479                          * Set the buffer up for an async read (XXX should
 480                          * we do this only if we do not wind up brelse()ing?).
 481                          * Set the block number if it isn't set, otherwise
 482                          * if it is make sure it matches the block number we
 483                          * expect.
 484                          */
 485                         tbp->b_flags |= B_ASYNC;
 486                         tbp->b_iocmd = BIO_READ;
 487                         if (tbp->b_blkno == tbp->b_lblkno) {
 488                                 tbp->b_blkno = bn;
 489                         } else if (tbp->b_blkno != bn) {
 490                                 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object);
 491                                 goto clean_sbusy;
 492                         }
 493                 }
 494                 /*
 495                  * XXX fbp from caller may not be B_ASYNC, but we are going
 496                  * to biodone() it in cluster_callback() anyway
 497                  */
 498                 BUF_KERNPROC(tbp);
 499                 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head,
 500                         tbp, b_cluster.cluster_entry);
 501                 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object);
 502                 for (j = 0; j < tbp->b_npages; j += 1) {
 503                         vm_page_t m;
 504                         m = tbp->b_pages[j];
 505                         if ((bp->b_npages == 0) ||
 506                             (bp->b_pages[bp->b_npages-1] != m)) {
 507                                 bp->b_pages[bp->b_npages] = m;
 508                                 bp->b_npages++;
 509                         }
 510                         if (m->valid == VM_PAGE_BITS_ALL)
 511                                 tbp->b_pages[j] = bogus_page;
 512                 }
 513                 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object);
 514                 /*
 515                  * Don't inherit tbp->b_bufsize as it may be larger due to
 516                  * a non-page-aligned size.  Instead just aggregate using
 517                  * 'size'.
 518                  */
 519                 if (tbp->b_bcount != size)
 520                         printf("warning: tbp->b_bcount wrong %ld vs %ld\n", tbp->b_bcount, size);
 521                 if (tbp->b_bufsize != size)
 522                         printf("warning: tbp->b_bufsize wrong %ld vs %ld\n", tbp->b_bufsize, size);
 523                 bp->b_bcount += size;
 524                 bp->b_bufsize += size;
 525         }
 526
 527         /*
 528          * Fully valid pages in the cluster are already good and do not need
 529          * to be re-read from disk.  Replace the page with bogus_page
 530          */
 531         VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
 532         for (j = 0; j < bp->b_npages; j++) {
 533                 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[j]->object);
 534                 if (bp->b_pages[j]->valid == VM_PAGE_BITS_ALL)
 535                         bp->b_pages[j] = bogus_page;
 536         }
 537         VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
 538         if (bp->b_bufsize > bp->b_kvasize)
 539                 panic("cluster_rbuild: b_bufsize(%ld) > b_kvasize(%d)\n",
 540                     bp->b_bufsize, bp->b_kvasize);
 541
 542         if (buf_mapped(bp)) {
 543                 pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
 544                     (vm_page_t *)bp->b_pages, bp->b_npages);
 545         }
 546         return (bp);
 547 }
 548
 549 /*
 550  * Cleanup after a clustered read or write.
 551  * This is complicated by the fact that any of the buffers might have
 552  * extra memory (if there were no empty buffer headers at allocbuf time)
 553  * that we will need to shift around.
 554  */
 555 static void
 556 cluster_callback(bp)
 557         struct buf *bp;
 558 {
 559         struct buf *nbp, *tbp;
 560         int error = 0;
 561
 562         /*
 563          * Must propagate errors to all the components.
 564          */
 565         if (bp->b_ioflags & BIO_ERROR)
 566                 error = bp->b_error;
 567
 568         if (buf_mapped(bp)) {
 569                 pmap_qremove(trunc_page((vm_offset_t) bp->b_data),
 570                     bp->b_npages);
 571         }
 572         /*
 573          * Move memory from the large cluster buffer into the component
 574          * buffers and mark IO as done on these.
 575          */
 576         for (tbp = TAILQ_FIRST(&bp->b_cluster.cluster_head);
 577                 tbp; tbp = nbp) {
 578                 nbp = TAILQ_NEXT(&tbp->b_cluster, cluster_entry);
 579                 if (error) {
 580                         tbp->b_ioflags |= BIO_ERROR;
 581                         tbp->b_error = error;
 582                 } else {
 583                         tbp->b_dirtyoff = tbp->b_dirtyend = 0;
 584                         tbp->b_flags &= ~B_INVAL;
 585                         tbp->b_ioflags &= ~BIO_ERROR;
 586                         /*
 587                          * XXX the bdwrite()/bqrelse() issued during
 588                          * cluster building clears B_RELBUF (see bqrelse()
 589                          * comment).  If direct I/O was specified, we have
 590                          * to restore it here to allow the buffer and VM
 591                          * to be freed.
 592                          */
 593                         if (tbp->b_flags & B_DIRECT)
 594                                 tbp->b_flags |= B_RELBUF;
 595                 }
 596                 bufdone(tbp);
 597         }
 598         pbrelvp(bp);
 599         relpbuf(bp, &cluster_pbuf_freecnt);
 600 }
 601
 602 /*
 603  *      cluster_wbuild_wb:
 604  *
 605  *      Implement modified write build for cluster.
 606  *
 607  *              write_behind = 0        write behind disabled
 608  *              write_behind = 1        write behind normal (default)
 609  *              write_behind = 2        write behind backed-off
 610  */
 611
 612 static __inline int
 613 cluster_wbuild_wb(struct vnode *vp, long size, daddr_t start_lbn, int len,
 614     int gbflags)
 615 {
 616         int r = 0;
 617
 618         switch (write_behind) {
 619         case 2:
 620                 if (start_lbn < len)
 621                         break;
 622                 start_lbn -= len;
 623                 /* FALLTHROUGH */
 624         case 1:
 625                 r = cluster_wbuild(vp, size, start_lbn, len, gbflags);
 626                 /* FALLTHROUGH */
 627         default:
 628                 /* FALLTHROUGH */
 629                 break;
 630         }
 631         return(r);
 632 }
 633
 634 /*
 635  * Do clustered write for FFS.
 636  *
 637  * Three cases:
 638  *      1. Write is not sequential (write asynchronously)
 639  *      Write is sequential:
 640  *      2.      beginning of cluster - begin cluster
 641  *      3.      middle of a cluster - add to cluster
 642  *      4.      end of a cluster - asynchronously write cluster
 643  */
 644 void
 645 cluster_write(struct vnode *vp, struct buf *bp, u_quad_t filesize, int seqcount,
 646     int gbflags)
 647 {
 648         daddr_t lbn;
 649         int maxclen, cursize;
 650         int lblocksize;
 651         int async;
 652
 653         if (!unmapped_buf_allowed)
 654                 gbflags &= ~GB_UNMAPPED;
 655
 656         if (vp->v_type == VREG) {
 657                 async = DOINGASYNC(vp);
 658                 lblocksize = vp->v_mount->mnt_stat.f_iosize;
 659         } else {
 660                 async = 0;
 661                 lblocksize = bp->b_bufsize;
 662         }
 663         lbn = bp->b_lblkno;
 664         KASSERT(bp->b_offset != NOOFFSET, ("cluster_write: no buffer offset"));
 665
 666         /* Initialize vnode to beginning of file. */
 667         if (lbn == 0)
 668                 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0;
 669
 670         if (vp->v_clen == 0 || lbn != vp->v_lastw + 1 ||
 671             (bp->b_blkno != vp->v_lasta + btodb(lblocksize))) {
 672                 maxclen = vp->v_mount->mnt_iosize_max / lblocksize - 1;
 673                 if (vp->v_clen != 0) {
 674                         /*
 675                          * Next block is not sequential.
 676                          *
 677                          * If we are not writing at end of file, the process
 678                          * seeked to another point in the file since its last
 679                          * write, or we have reached our maximum cluster size,
 680                          * then push the previous cluster. Otherwise try
 681                          * reallocating to make it sequential.
 682                          *
 683                          * Change to algorithm: only push previous cluster if
 684                          * it was sequential from the point of view of the
 685                          * seqcount heuristic, otherwise leave the buffer
 686                          * intact so we can potentially optimize the I/O
 687                          * later on in the buf_daemon or update daemon
 688                          * flush.
 689                          */
 690                         cursize = vp->v_lastw - vp->v_cstart + 1;
 691                         if (((u_quad_t) bp->b_offset + lblocksize) != filesize ||
 692                             lbn != vp->v_lastw + 1 || vp->v_clen <= cursize) {
 693                                 if (!async && seqcount > 0) {
 694                                         cluster_wbuild_wb(vp, lblocksize,
 695                                             vp->v_cstart, cursize, gbflags);
 696                                 }
 697                         } else {
 698                                 struct buf **bpp, **endbp;
 699                                 struct cluster_save *buflist;
 700
 701                                 buflist = cluster_collectbufs(vp, bp, gbflags);
 702                                 endbp = &buflist->bs_children
 703                                     [buflist->bs_nchildren - 1];
 704                                 if (VOP_REALLOCBLKS(vp, buflist)) {
 705                                         /*
 706                                          * Failed, push the previous cluster
 707                                          * if *really* writing sequentially
 708                                          * in the logical file (seqcount > 1),
 709                                          * otherwise delay it in the hopes that
 710                                          * the low level disk driver can
 711                                          * optimize the write ordering.
 712                                          */
 713                                         for (bpp = buflist->bs_children;
 714                                              bpp < endbp; bpp++)
 715                                                 brelse(*bpp);
 716                                         free(buflist, M_SEGMENT);
 717                                         if (seqcount > 1) {
 718                                                 cluster_wbuild_wb(vp,
 719                                                     lblocksize, vp->v_cstart,
 720                                                     cursize, gbflags);
 721                                         }
 722                                 } else {
 723                                         /*
 724                                          * Succeeded, keep building cluster.
 725                                          */
 726                                         for (bpp = buflist->bs_children;
 727                                              bpp <= endbp; bpp++)
 728                                                 bdwrite(*bpp);
 729                                         free(buflist, M_SEGMENT);
 730                                         vp->v_lastw = lbn;
 731                                         vp->v_lasta = bp->b_blkno;
 732                                         return;
 733                                 }
 734                         }
 735                 }
 736                 /*
 737                  * Consider beginning a cluster. If at end of file, make
 738                  * cluster as large as possible, otherwise find size of
 739                  * existing cluster.
 740                  */
 741                 if ((vp->v_type == VREG) &&
 742                         ((u_quad_t) bp->b_offset + lblocksize) != filesize &&
 743                     (bp->b_blkno == bp->b_lblkno) &&
 744                     (VOP_BMAP(vp, lbn, NULL, &bp->b_blkno, &maxclen, NULL) ||
 745                      bp->b_blkno == -1)) {
 746                         bawrite(bp);
 747                         vp->v_clen = 0;
 748                         vp->v_lasta = bp->b_blkno;
 749                         vp->v_cstart = lbn + 1;
 750                         vp->v_lastw = lbn;
 751                         return;
 752                 }
 753                 vp->v_clen = maxclen;
 754                 if (!async && maxclen == 0) {   /* I/O not contiguous */
 755                         vp->v_cstart = lbn + 1;
 756                         bawrite(bp);
 757                 } else {        /* Wait for rest of cluster */
 758                         vp->v_cstart = lbn;
 759                         bdwrite(bp);
 760                 }
 761         } else if (lbn == vp->v_cstart + vp->v_clen) {
 762                 /*
 763                  * At end of cluster, write it out if seqcount tells us we
 764                  * are operating sequentially, otherwise let the buf or
 765                  * update daemon handle it.
 766                  */
 767                 bdwrite(bp);
 768                 if (seqcount > 1) {
 769                         cluster_wbuild_wb(vp, lblocksize, vp->v_cstart,
 770                             vp->v_clen + 1, gbflags);
 771                 }
 772                 vp->v_clen = 0;
 773                 vp->v_cstart = lbn + 1;
 774         } else if (vm_page_count_severe()) {
 775                 /*
 776                  * We are low on memory, get it going NOW
 777                  */
 778                 bawrite(bp);
 779         } else {
 780                 /*
 781                  * In the middle of a cluster, so just delay the I/O for now.
 782                  */
 783                 bdwrite(bp);
 784         }
 785         vp->v_lastw = lbn;
 786         vp->v_lasta = bp->b_blkno;
 787 }
 788
 789
 790 /*
 791  * This is an awful lot like cluster_rbuild...wish they could be combined.
 792  * The last lbn argument is the current block on which I/O is being
 793  * performed.  Check to see that it doesn't fall in the middle of
 794  * the current block (if last_bp == NULL).
 795  */
 796 int
 797 cluster_wbuild(struct vnode *vp, long size, daddr_t start_lbn, int len,
 798     int gbflags)
 799 {
 800         struct buf *bp, *tbp;
 801         struct bufobj *bo;
 802         int i, j;
 803         int totalwritten = 0;
 804         int dbsize = btodb(size);
 805
 806         if (!unmapped_buf_allowed)
 807                 gbflags &= ~GB_UNMAPPED;
 808
 809         bo = &vp->v_bufobj;
 810         while (len > 0) {
 811                 /*
 812                  * If the buffer is not delayed-write (i.e. dirty), or it
 813                  * is delayed-write but either locked or inval, it cannot
 814                  * partake in the clustered write.
 815                  */
 816                 BO_LOCK(bo);
 817                 if ((tbp = gbincore(&vp->v_bufobj, start_lbn)) == NULL ||
 818                     (tbp->b_vflags & BV_BKGRDINPROG)) {
 819                         BO_UNLOCK(bo);
 820                         ++start_lbn;
 821                         --len;
 822                         continue;
 823                 }
 824                 if (BUF_LOCK(tbp,
 825                     LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, BO_LOCKPTR(bo))) {
 826                         ++start_lbn;
 827                         --len;
 828                         continue;
 829                 }
 830                 if ((tbp->b_flags & (B_INVAL | B_DELWRI)) != B_DELWRI) {
 831                         BUF_UNLOCK(tbp);
 832                         ++start_lbn;
 833                         --len;
 834                         continue;
 835                 }
 836                 bremfree(tbp);
 837                 tbp->b_flags &= ~B_DONE;
 838
 839                 /*
 840                  * Extra memory in the buffer, punt on this buffer.
 841                  * XXX we could handle this in most cases, but we would
 842                  * have to push the extra memory down to after our max
 843                  * possible cluster size and then potentially pull it back
 844                  * up if the cluster was terminated prematurely--too much
 845                  * hassle.
 846                  */
 847                 if (((tbp->b_flags & (B_CLUSTEROK | B_MALLOC | B_VMIO)) !=
 848                      (B_CLUSTEROK | B_VMIO)) ||
 849                   (tbp->b_bcount != tbp->b_bufsize) ||
 850                   (tbp->b_bcount != size) ||
 851                   (len == 1) ||
 852                   ((bp = (vp->v_vflag & VV_MD) != 0 ?
 853                   trypbuf(&cluster_pbuf_freecnt) :
 854                   getpbuf(&cluster_pbuf_freecnt)) == NULL)) {
 855                         totalwritten += tbp->b_bufsize;
 856                         bawrite(tbp);
 857                         ++start_lbn;
 858                         --len;
 859                         continue;
 860                 }
 861
 862                 /*
 863                  * We got a pbuf to make the cluster in.
 864                  * so initialise it.
 865                  */
 866                 TAILQ_INIT(&bp->b_cluster.cluster_head);
 867                 bp->b_bcount = 0;
 868                 bp->b_bufsize = 0;
 869                 bp->b_npages = 0;
 870                 if (tbp->b_wcred != NOCRED)
 871                         bp->b_wcred = crhold(tbp->b_wcred);
 872
 873                 bp->b_blkno = tbp->b_blkno;
 874                 bp->b_lblkno = tbp->b_lblkno;
 875                 bp->b_offset = tbp->b_offset;
 876
 877                 /*
 878                  * We are synthesizing a buffer out of vm_page_t's, but
 879                  * if the block size is not page aligned then the starting
 880                  * address may not be either.  Inherit the b_data offset
 881                  * from the original buffer.
 882                  */
 883                 if ((gbflags & GB_UNMAPPED) == 0 ||
 884                     (tbp->b_flags & B_VMIO) == 0) {
 885                         bp->b_data = (char *)((vm_offset_t)bp->b_data |
 886                             ((vm_offset_t)tbp->b_data & PAGE_MASK));
 887                 } else {
 888                         bp->b_data = unmapped_buf;
 889                 }
 890                 bp->b_flags |= B_CLUSTER | (tbp->b_flags & (B_VMIO |
 891                     B_NEEDCOMMIT));
 892                 bp->b_iodone = cluster_callback;
 893                 pbgetvp(vp, bp);
 894                 /*
 895                  * From this location in the file, scan forward to see
 896                  * if there are buffers with adjacent data that need to
 897                  * be written as well.
 898                  */
 899                 for (i = 0; i < len; ++i, ++start_lbn) {
 900                         if (i != 0) { /* If not the first buffer */
 901                                 /*
 902                                  * If the adjacent data is not even in core it
 903                                  * can't need to be written.
 904                                  */
 905                                 BO_LOCK(bo);
 906                                 if ((tbp = gbincore(bo, start_lbn)) == NULL ||
 907                                     (tbp->b_vflags & BV_BKGRDINPROG)) {
 908                                         BO_UNLOCK(bo);
 909                                         break;
 910                                 }
 911
 912                                 /*
 913                                  * If it IS in core, but has different
 914                                  * characteristics, or is locked (which
 915                                  * means it could be undergoing a background
 916                                  * I/O or be in a weird state), then don't
 917                                  * cluster with it.
 918                                  */
 919                                 if (BUF_LOCK(tbp,
 920                                     LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK,
 921                                     BO_LOCKPTR(bo)))
 922                                         break;
 923
 924                                 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK |
 925                                     B_INVAL | B_DELWRI | B_NEEDCOMMIT))
 926                                     != (B_DELWRI | B_CLUSTEROK |
 927                                     (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) ||
 928                                     tbp->b_wcred != bp->b_wcred) {
 929                                         BUF_UNLOCK(tbp);
 930                                         break;
 931                                 }
 932
 933                                 /*
 934                                  * Check that the combined cluster
 935                                  * would make sense with regard to pages
 936                                  * and would not be too large
 937                                  */
 938                                 if ((tbp->b_bcount != size) ||
 939                                   ((bp->b_blkno + (dbsize * i)) !=
 940                                     tbp->b_blkno) ||
 941                                   ((tbp->b_npages + bp->b_npages) >
 942                                     (vp->v_mount->mnt_iosize_max / PAGE_SIZE))) {
 943                                         BUF_UNLOCK(tbp);
 944                                         break;
 945                                 }
 946
 947                                 /*
 948                                  * Ok, it's passed all the tests,
 949                                  * so remove it from the free list
 950                                  * and mark it busy. We will use it.
 951                                  */
 952                                 bremfree(tbp);
 953                                 tbp->b_flags &= ~B_DONE;
 954                         } /* end of code for non-first buffers only */
 955                         /*
 956                          * If the IO is via the VM then we do some
 957                          * special VM hackery (yuck).  Since the buffer's
 958                          * block size may not be page-aligned it is possible
 959                          * for a page to be shared between two buffers.  We
 960                          * have to get rid of the duplication when building
 961                          * the cluster.
 962                          */
 963                         if (tbp->b_flags & B_VMIO) {
 964                                 vm_page_t m;
 965
 966                                 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object);
 967                                 if (i == 0) {
 968                                         vfs_drain_busy_pages(tbp);
 969                                 } else { /* if not first buffer */
 970                                         for (j = 0; j < tbp->b_npages; j += 1) {
 971                                                 m = tbp->b_pages[j];
 972                                                 if (vm_page_xbusied(m)) {
 973                                                         VM_OBJECT_WUNLOCK(
 974                                                             tbp->b_object);
 975                                                         bqrelse(tbp);
 976                                                         goto finishcluster;
 977                                                 }
 978                                         }
 979                                 }
 980                                 for (j = 0; j < tbp->b_npages; j += 1) {
 981                                         m = tbp->b_pages[j];
 982                                         vm_page_sbusy(m);
 983                                         vm_object_pip_add(m->object, 1);
 984                                         if ((bp->b_npages == 0) ||
 985                                           (bp->b_pages[bp->b_npages - 1] != m)) {
 986                                                 bp->b_pages[bp->b_npages] = m;
 987                                                 bp->b_npages++;
 988                                         }
 989                                 }
 990                                 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object);
 991                         }
 992                         bp->b_bcount += size;
 993                         bp->b_bufsize += size;
 994                         /*
 995                          * If any of the clustered buffers have their
 996                          * B_BARRIER flag set, transfer that request to
 997                          * the cluster.
 998                          */
 999                         bp->b_flags |= (tbp->b_flags & B_BARRIER);
1000                         tbp->b_flags &= ~(B_DONE | B_BARRIER);
1001                         tbp->b_flags |= B_ASYNC;
1002                         tbp->b_ioflags &= ~BIO_ERROR;
1003                         tbp->b_iocmd = BIO_WRITE;
1004                         bundirty(tbp);
1005                         reassignbuf(tbp);               /* put on clean list */
1006                         bufobj_wref(tbp->b_bufobj);
1007                         BUF_KERNPROC(tbp);
1008                         buf_track(tbp, __func__);
1009                         TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head,
1010                                 tbp, b_cluster.cluster_entry);
1011                 }
1012         finishcluster:
1013                 if (buf_mapped(bp)) {
1014                         pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
1015                             (vm_page_t *)bp->b_pages, bp->b_npages);
1016                 }
1017                 if (bp->b_bufsize > bp->b_kvasize)
1018                         panic(
1019                             "cluster_wbuild: b_bufsize(%ld) > b_kvasize(%d)\n",
1020                             bp->b_bufsize, bp->b_kvasize);
1021                 totalwritten += bp->b_bufsize;
1022                 bp->b_dirtyoff = 0;
1023                 bp->b_dirtyend = bp->b_bufsize;
1024                 bawrite(bp);
1025
1026                 len -= i;
1027         }
1028         return totalwritten;
1029 }
1030
1031 /*
1032  * Collect together all the buffers in a cluster.
1033  * Plus add one additional buffer.
1034  */
1035 static struct cluster_save *
1036 cluster_collectbufs(struct vnode *vp, struct buf *last_bp, int gbflags)
1037 {
1038         struct cluster_save *buflist;
1039         struct buf *bp;
1040         daddr_t lbn;
1041         int i, len;
1042
1043         len = vp->v_lastw - vp->v_cstart + 1;
1044         buflist = malloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist),
1045             M_SEGMENT, M_WAITOK);
1046         buflist->bs_nchildren = 0;
1047         buflist->bs_children = (struct buf **) (buflist + 1);
1048         for (lbn = vp->v_cstart, i = 0; i < len; lbn++, i++) {
1049                 (void)bread_gb(vp, lbn, last_bp->b_bcount, NOCRED,
1050                     gbflags, &bp);
1051                 buflist->bs_children[i] = bp;
1052                 if (bp->b_blkno == bp->b_lblkno)
1053                         VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno,
1054                                 NULL, NULL);
1055         }
1056         buflist->bs_children[i] = bp = last_bp;
1057         if (bp->b_blkno == bp->b_lblkno)
1058                 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
1059         buflist->bs_nchildren = i + 1;
1060         return (buflist);
1061 }