sys/kern/vfs_cluster.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-3-Clause
   3  *
   4  * Copyright (c) 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  * Modifications/enhancements:
   7  *      Copyright (c) 1995 John S. Dyson.  All rights reserved.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions
  11  * are met:
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in the
  16  *    documentation and/or other materials provided with the distribution.
  17  * 3. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  *
  33  *      @(#)vfs_cluster.c       8.7 (Berkeley) 2/13/94
  34  */
  35
  36 #include <sys/cdefs.h>
  37 __FBSDID("$FreeBSD$");
  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 static MALLOC_DEFINE(M_SEGMENT, "cl_savebuf", "cluster_save buffer");
  58 static uma_zone_t cluster_pbuf_zone;
  59
  60 static void cluster_init(void *);
  61 static struct cluster_save *cluster_collectbufs(struct vnode *vp,
  62             struct buf *last_bp, int gbflags);
  63 static struct buf *cluster_rbuild(struct vnode *vp, u_quad_t filesize,
  64             daddr_t lbn, daddr_t blkno, long size, int run, int gbflags,
  65             struct buf *fbp);
  66 static void cluster_callback(struct buf *);
  67
  68 static int write_behind = 1;
  69 SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0,
  70     "Cluster write-behind; 0: disable, 1: enable, 2: backed off");
  71
  72 static int read_max = 64;
  73 SYSCTL_INT(_vfs, OID_AUTO, read_max, CTLFLAG_RW, &read_max, 0,
  74     "Cluster read-ahead max block count");
  75
  76 static int read_min = 1;
  77 SYSCTL_INT(_vfs, OID_AUTO, read_min, CTLFLAG_RW, &read_min, 0,
  78     "Cluster read min block count");
  79
  80 SYSINIT(cluster, SI_SUB_CPU, SI_ORDER_ANY, cluster_init, NULL);
  81
  82 static void
  83 cluster_init(void *dummy)
  84 {
  85
  86         cluster_pbuf_zone = pbuf_zsecond_create("clpbuf", nswbuf / 2);
  87 }
  88
  89 /*
  90  * Read data to a buf, including read-ahead if we find this to be beneficial.
  91  * cluster_read replaces bread.
  92  */
  93 int
  94 cluster_read(struct vnode *vp, u_quad_t filesize, daddr_t lblkno, long size,
  95     struct ucred *cred, long totread, int seqcount, int gbflags,
  96     struct buf **bpp)
  97 {
  98         struct buf *bp, *rbp, *reqbp;
  99         struct bufobj *bo;
 100         struct thread *td;
 101         daddr_t blkno, origblkno;
 102         int maxra, racluster;
 103         int error, ncontig;
 104         int i;
 105
 106         error = 0;
 107         td = curthread;
 108         bo = &vp->v_bufobj;
 109         if (!unmapped_buf_allowed)
 110                 gbflags &= ~GB_UNMAPPED;
 111
 112         /*
 113          * Try to limit the amount of read-ahead by a few
 114          * ad-hoc parameters.  This needs work!!!
 115          */
 116         racluster = vp->v_mount->mnt_iosize_max / size;
 117         maxra = seqcount;
 118         maxra = min(read_max, maxra);
 119         maxra = min(nbuf/8, maxra);
 120         if (((u_quad_t)(lblkno + maxra + 1) * size) > filesize)
 121                 maxra = (filesize / size) - lblkno;
 122
 123         /*
 124          * get the requested block
 125          */
 126         error = getblkx(vp, lblkno, lblkno, size, 0, 0, gbflags, &bp);
 127         if (error != 0) {
 128                 *bpp = NULL;
 129                 return (error);
 130         }
 131         gbflags &= ~GB_NOSPARSE;
 132         origblkno = lblkno;
 133         *bpp = reqbp = bp;
 134
 135         /*
 136          * if it is in the cache, then check to see if the reads have been
 137          * sequential.  If they have, then try some read-ahead, otherwise
 138          * back-off on prospective read-aheads.
 139          */
 140         if (bp->b_flags & B_CACHE) {
 141                 if (!seqcount) {
 142                         return 0;
 143                 } else if ((bp->b_flags & B_RAM) == 0) {
 144                         return 0;
 145                 } else {
 146                         bp->b_flags &= ~B_RAM;
 147                         BO_RLOCK(bo);
 148                         for (i = 1; i < maxra; i++) {
 149                                 /*
 150                                  * Stop if the buffer does not exist or it
 151                                  * is invalid (about to go away?)
 152                                  */
 153                                 rbp = gbincore(&vp->v_bufobj, lblkno+i);
 154                                 if (rbp == NULL || (rbp->b_flags & B_INVAL))
 155                                         break;
 156
 157                                 /*
 158                                  * Set another read-ahead mark so we know
 159                                  * to check again. (If we can lock the
 160                                  * buffer without waiting)
 161                                  */
 162                                 if ((((i % racluster) == (racluster - 1)) ||
 163                                     (i == (maxra - 1)))
 164                                     && (0 == BUF_LOCK(rbp,
 165                                         LK_EXCLUSIVE | LK_NOWAIT, NULL))) {
 166                                         rbp->b_flags |= B_RAM;
 167                                         BUF_UNLOCK(rbp);
 168                                 }
 169                         }
 170                         BO_RUNLOCK(bo);
 171                         if (i >= maxra) {
 172                                 return 0;
 173                         }
 174                         lblkno += i;
 175                 }
 176                 reqbp = bp = NULL;
 177         /*
 178          * If it isn't in the cache, then get a chunk from
 179          * disk if sequential, otherwise just get the block.
 180          */
 181         } else {
 182                 off_t firstread = bp->b_offset;
 183                 int nblks;
 184                 long minread;
 185
 186                 KASSERT(bp->b_offset != NOOFFSET,
 187                     ("cluster_read: no buffer offset"));
 188
 189                 ncontig = 0;
 190
 191                 /*
 192                  * Adjust totread if needed
 193                  */
 194                 minread = read_min * size;
 195                 if (minread > totread)
 196                         totread = minread;
 197
 198                 /*
 199                  * Compute the total number of blocks that we should read
 200                  * synchronously.
 201                  */
 202                 if (firstread + totread > filesize)
 203                         totread = filesize - firstread;
 204                 nblks = howmany(totread, size);
 205                 if (nblks > racluster)
 206                         nblks = racluster;
 207
 208                 /*
 209                  * Now compute the number of contiguous blocks.
 210                  */
 211                 if (nblks > 1) {
 212                         error = VOP_BMAP(vp, lblkno, NULL,
 213                                 &blkno, &ncontig, NULL);
 214                         /*
 215                          * If this failed to map just do the original block.
 216                          */
 217                         if (error || blkno == -1)
 218                                 ncontig = 0;
 219                 }
 220
 221                 /*
 222                  * If we have contiguous data available do a cluster
 223                  * otherwise just read the requested block.
 224                  */
 225                 if (ncontig) {
 226                         /* Account for our first block. */
 227                         ncontig = min(ncontig + 1, nblks);
 228                         if (ncontig < nblks)
 229                                 nblks = ncontig;
 230                         bp = cluster_rbuild(vp, filesize, lblkno,
 231                             blkno, size, nblks, gbflags, bp);
 232                         lblkno += (bp->b_bufsize / size);
 233                 } else {
 234                         bp->b_flags |= B_RAM;
 235                         bp->b_iocmd = BIO_READ;
 236                         lblkno += 1;
 237                 }
 238         }
 239
 240         /*
 241          * handle the synchronous read so that it is available ASAP.
 242          */
 243         if (bp) {
 244                 if ((bp->b_flags & B_CLUSTER) == 0) {
 245                         vfs_busy_pages(bp, 0);
 246                 }
 247                 bp->b_flags &= ~B_INVAL;
 248                 bp->b_ioflags &= ~BIO_ERROR;
 249                 if ((bp->b_flags & B_ASYNC) || bp->b_iodone != NULL)
 250                         BUF_KERNPROC(bp);
 251                 bp->b_iooffset = dbtob(bp->b_blkno);
 252                 bstrategy(bp);
 253 #ifdef RACCT
 254                 if (racct_enable) {
 255                         PROC_LOCK(td->td_proc);
 256                         racct_add_buf(td->td_proc, bp, 0);
 257                         PROC_UNLOCK(td->td_proc);
 258                 }
 259 #endif /* RACCT */
 260                 td->td_ru.ru_inblock++;
 261         }
 262
 263         /*
 264          * If we have been doing sequential I/O, then do some read-ahead.
 265          */
 266         while (lblkno < (origblkno + maxra)) {
 267                 error = VOP_BMAP(vp, lblkno, NULL, &blkno, &ncontig, NULL);
 268                 if (error)
 269                         break;
 270
 271                 if (blkno == -1)
 272                         break;
 273
 274                 /*
 275                  * We could throttle ncontig here by maxra but we might as
 276                  * well read the data if it is contiguous.  We're throttled
 277                  * by racluster anyway.
 278                  */
 279                 if (ncontig) {
 280                         ncontig = min(ncontig + 1, racluster);
 281                         rbp = cluster_rbuild(vp, filesize, lblkno, blkno,
 282                             size, ncontig, gbflags, NULL);
 283                         lblkno += (rbp->b_bufsize / size);
 284                         if (rbp->b_flags & B_DELWRI) {
 285                                 bqrelse(rbp);
 286                                 continue;
 287                         }
 288                 } else {
 289                         rbp = getblk(vp, lblkno, size, 0, 0, gbflags);
 290                         lblkno += 1;
 291                         if (rbp->b_flags & B_DELWRI) {
 292                                 bqrelse(rbp);
 293                                 continue;
 294                         }
 295                         rbp->b_flags |= B_ASYNC | B_RAM;
 296                         rbp->b_iocmd = BIO_READ;
 297                         rbp->b_blkno = blkno;
 298                 }
 299                 if (rbp->b_flags & B_CACHE) {
 300                         rbp->b_flags &= ~B_ASYNC;
 301                         bqrelse(rbp);
 302                         continue;
 303                 }
 304                 if ((rbp->b_flags & B_CLUSTER) == 0) {
 305                         vfs_busy_pages(rbp, 0);
 306                 }
 307                 rbp->b_flags &= ~B_INVAL;
 308                 rbp->b_ioflags &= ~BIO_ERROR;
 309                 if ((rbp->b_flags & B_ASYNC) || rbp->b_iodone != NULL)
 310                         BUF_KERNPROC(rbp);
 311                 rbp->b_iooffset = dbtob(rbp->b_blkno);
 312                 bstrategy(rbp);
 313 #ifdef RACCT
 314                 if (racct_enable) {
 315                         PROC_LOCK(td->td_proc);
 316                         racct_add_buf(td->td_proc, rbp, 0);
 317                         PROC_UNLOCK(td->td_proc);
 318                 }
 319 #endif /* RACCT */
 320                 td->td_ru.ru_inblock++;
 321         }
 322
 323         if (reqbp) {
 324                 /*
 325                  * Like bread, always brelse() the buffer when
 326                  * returning an error.
 327                  */
 328                 error = bufwait(reqbp);
 329                 if (error != 0) {
 330                         brelse(reqbp);
 331                         *bpp = NULL;
 332                 }
 333         }
 334         return (error);
 335 }
 336
 337 /*
 338  * If blocks are contiguous on disk, use this to provide clustered
 339  * read ahead.  We will read as many blocks as possible sequentially
 340  * and then parcel them up into logical blocks in the buffer hash table.
 341  */
 342 static struct buf *
 343 cluster_rbuild(struct vnode *vp, u_quad_t filesize, daddr_t lbn,
 344     daddr_t blkno, long size, int run, int gbflags, struct buf *fbp)
 345 {
 346         struct buf *bp, *tbp;
 347         daddr_t bn;
 348         off_t off;
 349         long tinc, tsize;
 350         int i, inc, j, k, toff;
 351
 352         KASSERT(size == vp->v_mount->mnt_stat.f_iosize,
 353             ("cluster_rbuild: size %ld != f_iosize %jd\n",
 354             size, (intmax_t)vp->v_mount->mnt_stat.f_iosize));
 355
 356         /*
 357          * avoid a division
 358          */
 359         while ((u_quad_t) size * (lbn + run) > filesize) {
 360                 --run;
 361         }
 362
 363         if (fbp) {
 364                 tbp = fbp;
 365                 tbp->b_iocmd = BIO_READ;
 366         } else {
 367                 tbp = getblk(vp, lbn, size, 0, 0, gbflags);
 368                 if (tbp->b_flags & B_CACHE)
 369                         return tbp;
 370                 tbp->b_flags |= B_ASYNC | B_RAM;
 371                 tbp->b_iocmd = BIO_READ;
 372         }
 373         tbp->b_blkno = blkno;
 374         if( (tbp->b_flags & B_MALLOC) ||
 375                 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1) )
 376                 return tbp;
 377
 378         bp = uma_zalloc(cluster_pbuf_zone, M_NOWAIT);
 379         if (bp == NULL)
 380                 return tbp;
 381         MPASS((bp->b_flags & B_MAXPHYS) != 0);
 382
 383         /*
 384          * We are synthesizing a buffer out of vm_page_t's, but
 385          * if the block size is not page aligned then the starting
 386          * address may not be either.  Inherit the b_data offset
 387          * from the original buffer.
 388          */
 389         bp->b_flags = B_ASYNC | B_CLUSTER | B_VMIO;
 390         if ((gbflags & GB_UNMAPPED) != 0) {
 391                 bp->b_data = unmapped_buf;
 392         } else {
 393                 bp->b_data = (char *)((vm_offset_t)bp->b_data |
 394                     ((vm_offset_t)tbp->b_data & PAGE_MASK));
 395         }
 396         bp->b_iocmd = BIO_READ;
 397         bp->b_iodone = cluster_callback;
 398         bp->b_blkno = blkno;
 399         bp->b_lblkno = lbn;
 400         bp->b_offset = tbp->b_offset;
 401         KASSERT(bp->b_offset != NOOFFSET, ("cluster_rbuild: no buffer offset"));
 402         pbgetvp(vp, bp);
 403
 404         TAILQ_INIT(&bp->b_cluster.cluster_head);
 405
 406         bp->b_bcount = 0;
 407         bp->b_bufsize = 0;
 408         bp->b_npages = 0;
 409
 410         inc = btodb(size);
 411         for (bn = blkno, i = 0; i < run; ++i, bn += inc) {
 412                 if (i == 0) {
 413                         vm_object_pip_add(tbp->b_bufobj->bo_object,
 414                             tbp->b_npages);
 415                         vfs_busy_pages_acquire(tbp);
 416                 } else {
 417                         if ((bp->b_npages * PAGE_SIZE) +
 418                             round_page(size) > vp->v_mount->mnt_iosize_max) {
 419                                 break;
 420                         }
 421
 422                         tbp = getblk(vp, lbn + i, size, 0, 0, GB_LOCK_NOWAIT |
 423                             (gbflags & GB_UNMAPPED));
 424
 425                         /* Don't wait around for locked bufs. */
 426                         if (tbp == NULL)
 427                                 break;
 428
 429                         /*
 430                          * Stop scanning if the buffer is fully valid
 431                          * (marked B_CACHE), or locked (may be doing a
 432                          * background write), or if the buffer is not
 433                          * VMIO backed.  The clustering code can only deal
 434                          * with VMIO-backed buffers.  The bo lock is not
 435                          * required for the BKGRDINPROG check since it
 436                          * can not be set without the buf lock.
 437                          */
 438                         if ((tbp->b_vflags & BV_BKGRDINPROG) ||
 439                             (tbp->b_flags & B_CACHE) ||
 440                             (tbp->b_flags & B_VMIO) == 0) {
 441                                 bqrelse(tbp);
 442                                 break;
 443                         }
 444
 445                         /*
 446                          * The buffer must be completely invalid in order to
 447                          * take part in the cluster.  If it is partially valid
 448                          * then we stop.
 449                          */
 450                         off = tbp->b_offset;
 451                         tsize = size;
 452                         for (j = 0; tsize > 0; j++) {
 453                                 toff = off & PAGE_MASK;
 454                                 tinc = tsize;
 455                                 if (toff + tinc > PAGE_SIZE)
 456                                         tinc = PAGE_SIZE - toff;
 457                                 if (vm_page_trysbusy(tbp->b_pages[j]) == 0)
 458                                         break;
 459                                 if ((tbp->b_pages[j]->valid &
 460                                     vm_page_bits(toff, tinc)) != 0) {
 461                                         vm_page_sunbusy(tbp->b_pages[j]);
 462                                         break;
 463                                 }
 464                                 vm_object_pip_add(tbp->b_bufobj->bo_object, 1);
 465                                 off += tinc;
 466                                 tsize -= tinc;
 467                         }
 468                         if (tsize > 0) {
 469 clean_sbusy:
 470                                 vm_object_pip_wakeupn(tbp->b_bufobj->bo_object,
 471                                     j);
 472                                 for (k = 0; k < j; k++)
 473                                         vm_page_sunbusy(tbp->b_pages[k]);
 474                                 bqrelse(tbp);
 475                                 break;
 476                         }
 477
 478                         /*
 479                          * Set a read-ahead mark as appropriate
 480                          */
 481                         if ((fbp && (i == 1)) || (i == (run - 1)))
 482                                 tbp->b_flags |= B_RAM;
 483
 484                         /*
 485                          * Set the buffer up for an async read (XXX should
 486                          * we do this only if we do not wind up brelse()ing?).
 487                          * Set the block number if it isn't set, otherwise
 488                          * if it is make sure it matches the block number we
 489                          * expect.
 490                          */
 491                         tbp->b_flags |= B_ASYNC;
 492                         tbp->b_iocmd = BIO_READ;
 493                         if (tbp->b_blkno == tbp->b_lblkno) {
 494                                 tbp->b_blkno = bn;
 495                         } else if (tbp->b_blkno != bn) {
 496                                 goto clean_sbusy;
 497                         }
 498                 }
 499                 /*
 500                  * XXX fbp from caller may not be B_ASYNC, but we are going
 501                  * to biodone() it in cluster_callback() anyway
 502                  */
 503                 BUF_KERNPROC(tbp);
 504                 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head,
 505                         tbp, b_cluster.cluster_entry);
 506                 for (j = 0; j < tbp->b_npages; j += 1) {
 507                         vm_page_t m;
 508
 509                         m = tbp->b_pages[j];
 510                         if ((bp->b_npages == 0) ||
 511                             (bp->b_pages[bp->b_npages-1] != m)) {
 512                                 bp->b_pages[bp->b_npages] = m;
 513                                 bp->b_npages++;
 514                         }
 515                         if (vm_page_all_valid(m))
 516                                 tbp->b_pages[j] = bogus_page;
 517                 }
 518
 519                 /*
 520                  * Don't inherit tbp->b_bufsize as it may be larger due to
 521                  * a non-page-aligned size.  Instead just aggregate using
 522                  * 'size'.
 523                  */
 524                 if (tbp->b_bcount != size)
 525                         printf("warning: tbp->b_bcount wrong %ld vs %ld\n", tbp->b_bcount, size);
 526                 if (tbp->b_bufsize != size)
 527                         printf("warning: tbp->b_bufsize wrong %ld vs %ld\n", tbp->b_bufsize, size);
 528                 bp->b_bcount += size;
 529                 bp->b_bufsize += size;
 530         }
 531
 532         /*
 533          * Fully valid pages in the cluster are already good and do not need
 534          * to be re-read from disk.  Replace the page with bogus_page
 535          */
 536         for (j = 0; j < bp->b_npages; j++) {
 537                 if (vm_page_all_valid(bp->b_pages[j]))
 538                         bp->b_pages[j] = bogus_page;
 539         }
 540         if (bp->b_bufsize > bp->b_kvasize)
 541                 panic("cluster_rbuild: b_bufsize(%ld) > b_kvasize(%d)\n",
 542                     bp->b_bufsize, bp->b_kvasize);
 543
 544         if (buf_mapped(bp)) {
 545                 pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
 546                     (vm_page_t *)bp->b_pages, bp->b_npages);
 547         }
 548         return (bp);
 549 }
 550
 551 /*
 552  * Cleanup after a clustered read or write.
 553  * This is complicated by the fact that any of the buffers might have
 554  * extra memory (if there were no empty buffer headers at allocbuf time)
 555  * that we will need to shift around.
 556  */
 557 static void
 558 cluster_callback(struct buf *bp)
 559 {
 560         struct buf *nbp, *tbp;
 561         int error = 0;
 562
 563         /*
 564          * Must propagate errors to all the components.
 565          */
 566         if (bp->b_ioflags & BIO_ERROR)
 567                 error = bp->b_error;
 568
 569         if (buf_mapped(bp)) {
 570                 pmap_qremove(trunc_page((vm_offset_t) bp->b_data),
 571                     bp->b_npages);
 572         }
 573         /*
 574          * Move memory from the large cluster buffer into the component
 575          * buffers and mark IO as done on these.
 576          */
 577         for (tbp = TAILQ_FIRST(&bp->b_cluster.cluster_head);
 578                 tbp; tbp = nbp) {
 579                 nbp = TAILQ_NEXT(&tbp->b_cluster, cluster_entry);
 580                 if (error) {
 581                         tbp->b_ioflags |= BIO_ERROR;
 582                         tbp->b_error = error;
 583                 } else {
 584                         tbp->b_dirtyoff = tbp->b_dirtyend = 0;
 585                         tbp->b_flags &= ~B_INVAL;
 586                         tbp->b_ioflags &= ~BIO_ERROR;
 587                         /*
 588                          * XXX the bdwrite()/bqrelse() issued during
 589                          * cluster building clears B_RELBUF (see bqrelse()
 590                          * comment).  If direct I/O was specified, we have
 591                          * to restore it here to allow the buffer and VM
 592                          * to be freed.
 593                          */
 594                         if (tbp->b_flags & B_DIRECT)
 595                                 tbp->b_flags |= B_RELBUF;
 596                 }
 597                 bufdone(tbp);
 598         }
 599         pbrelvp(bp);
 600         uma_zfree(cluster_pbuf_zone, bp);
 601 }
 602
 603 /*
 604  *      cluster_wbuild_wb:
 605  *
 606  *      Implement modified write build for cluster.
 607  *
 608  *              write_behind = 0        write behind disabled
 609  *              write_behind = 1        write behind normal (default)
 610  *              write_behind = 2        write behind backed-off
 611  */
 612
 613 static __inline int
 614 cluster_wbuild_wb(struct vnode *vp, long size, daddr_t start_lbn, int len,
 615     int gbflags)
 616 {
 617         int r = 0;
 618
 619         switch (write_behind) {
 620         case 2:
 621                 if (start_lbn < len)
 622                         break;
 623                 start_lbn -= len;
 624                 /* FALLTHROUGH */
 625         case 1:
 626                 r = cluster_wbuild(vp, size, start_lbn, len, gbflags);
 627                 /* FALLTHROUGH */
 628         default:
 629                 /* FALLTHROUGH */
 630                 break;
 631         }
 632         return(r);
 633 }
 634
 635 /*
 636  * Do clustered write for FFS.
 637  *
 638  * Three cases:
 639  *      1. Write is not sequential (write asynchronously)
 640  *      Write is sequential:
 641  *      2.      beginning of cluster - begin cluster
 642  *      3.      middle of a cluster - add to cluster
 643  *      4.      end of a cluster - asynchronously write cluster
 644  */
 645 void
 646 cluster_write(struct vnode *vp, struct buf *bp, u_quad_t filesize, int seqcount,
 647     int gbflags)
 648 {
 649         daddr_t lbn;
 650         int maxclen, cursize;
 651         int lblocksize;
 652         int async;
 653
 654         if (!unmapped_buf_allowed)
 655                 gbflags &= ~GB_UNMAPPED;
 656
 657         if (vp->v_type == VREG) {
 658                 async = DOINGASYNC(vp);
 659                 lblocksize = vp->v_mount->mnt_stat.f_iosize;
 660         } else {
 661                 async = 0;
 662                 lblocksize = bp->b_bufsize;
 663         }
 664         lbn = bp->b_lblkno;
 665         KASSERT(bp->b_offset != NOOFFSET, ("cluster_write: no buffer offset"));
 666
 667         /* Initialize vnode to beginning of file. */
 668         if (lbn == 0)
 669                 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0;
 670
 671         if (vp->v_clen == 0 || lbn != vp->v_lastw + 1 ||
 672             (bp->b_blkno != vp->v_lasta + btodb(lblocksize))) {
 673                 maxclen = vp->v_mount->mnt_iosize_max / lblocksize - 1;
 674                 if (vp->v_clen != 0) {
 675                         /*
 676                          * Next block is not sequential.
 677                          *
 678                          * If we are not writing at end of file, the process
 679                          * seeked to another point in the file since its last
 680                          * write, or we have reached our maximum cluster size,
 681                          * then push the previous cluster. Otherwise try
 682                          * reallocating to make it sequential.
 683                          *
 684                          * Change to algorithm: only push previous cluster if
 685                          * it was sequential from the point of view of the
 686                          * seqcount heuristic, otherwise leave the buffer
 687                          * intact so we can potentially optimize the I/O
 688                          * later on in the buf_daemon or update daemon
 689                          * flush.
 690                          */
 691                         cursize = vp->v_lastw - vp->v_cstart + 1;
 692                         if (((u_quad_t) bp->b_offset + lblocksize) != filesize ||
 693                             lbn != vp->v_lastw + 1 || vp->v_clen <= cursize) {
 694                                 if (!async && seqcount > 0) {
 695                                         cluster_wbuild_wb(vp, lblocksize,
 696                                             vp->v_cstart, cursize, gbflags);
 697                                 }
 698                         } else {
 699                                 struct buf **bpp, **endbp;
 700                                 struct cluster_save *buflist;
 701
 702                                 buflist = cluster_collectbufs(vp, bp, gbflags);
 703                                 if (buflist == NULL) {
 704                                         /*
 705                                          * Cluster build failed so just write
 706                                          * it now.
 707                                          */
 708                                         bawrite(bp);
 709                                         return;
 710                                 }
 711                                 endbp = &buflist->bs_children
 712                                     [buflist->bs_nchildren - 1];
 713                                 if (VOP_REALLOCBLKS(vp, buflist)) {
 714                                         /*
 715                                          * Failed, push the previous cluster
 716                                          * if *really* writing sequentially
 717                                          * in the logical file (seqcount > 1),
 718                                          * otherwise delay it in the hopes that
 719                                          * the low level disk driver can
 720                                          * optimize the write ordering.
 721                                          */
 722                                         for (bpp = buflist->bs_children;
 723                                              bpp < endbp; bpp++)
 724                                                 brelse(*bpp);
 725                                         free(buflist, M_SEGMENT);
 726                                         if (seqcount > 1) {
 727                                                 cluster_wbuild_wb(vp,
 728                                                     lblocksize, vp->v_cstart,
 729                                                     cursize, gbflags);
 730                                         }
 731                                 } else {
 732                                         /*
 733                                          * Succeeded, keep building cluster.
 734                                          */
 735                                         for (bpp = buflist->bs_children;
 736                                              bpp <= endbp; bpp++)
 737                                                 bdwrite(*bpp);
 738                                         free(buflist, M_SEGMENT);
 739                                         vp->v_lastw = lbn;
 740                                         vp->v_lasta = bp->b_blkno;
 741                                         return;
 742                                 }
 743                         }
 744                 }
 745                 /*
 746                  * Consider beginning a cluster. If at end of file, make
 747                  * cluster as large as possible, otherwise find size of
 748                  * existing cluster.
 749                  */
 750                 if ((vp->v_type == VREG) &&
 751                         ((u_quad_t) bp->b_offset + lblocksize) != filesize &&
 752                     (bp->b_blkno == bp->b_lblkno) &&
 753                     (VOP_BMAP(vp, lbn, NULL, &bp->b_blkno, &maxclen, NULL) ||
 754                      bp->b_blkno == -1)) {
 755                         bawrite(bp);
 756                         vp->v_clen = 0;
 757                         vp->v_lasta = bp->b_blkno;
 758                         vp->v_cstart = lbn + 1;
 759                         vp->v_lastw = lbn;
 760                         return;
 761                 }
 762                 vp->v_clen = maxclen;
 763                 if (!async && maxclen == 0) {   /* I/O not contiguous */
 764                         vp->v_cstart = lbn + 1;
 765                         bawrite(bp);
 766                 } else {        /* Wait for rest of cluster */
 767                         vp->v_cstart = lbn;
 768                         bdwrite(bp);
 769                 }
 770         } else if (lbn == vp->v_cstart + vp->v_clen) {
 771                 /*
 772                  * At end of cluster, write it out if seqcount tells us we
 773                  * are operating sequentially, otherwise let the buf or
 774                  * update daemon handle it.
 775                  */
 776                 bdwrite(bp);
 777                 if (seqcount > 1) {
 778                         cluster_wbuild_wb(vp, lblocksize, vp->v_cstart,
 779                             vp->v_clen + 1, gbflags);
 780                 }
 781                 vp->v_clen = 0;
 782                 vp->v_cstart = lbn + 1;
 783         } else if (vm_page_count_severe()) {
 784                 /*
 785                  * We are low on memory, get it going NOW
 786                  */
 787                 bawrite(bp);
 788         } else {
 789                 /*
 790                  * In the middle of a cluster, so just delay the I/O for now.
 791                  */
 792                 bdwrite(bp);
 793         }
 794         vp->v_lastw = lbn;
 795         vp->v_lasta = bp->b_blkno;
 796 }
 797
 798 /*
 799  * This is an awful lot like cluster_rbuild...wish they could be combined.
 800  * The last lbn argument is the current block on which I/O is being
 801  * performed.  Check to see that it doesn't fall in the middle of
 802  * the current block (if last_bp == NULL).
 803  */
 804 int
 805 cluster_wbuild(struct vnode *vp, long size, daddr_t start_lbn, int len,
 806     int gbflags)
 807 {
 808         struct buf *bp, *tbp;
 809         struct bufobj *bo;
 810         int i, j;
 811         int totalwritten = 0;
 812         int dbsize = btodb(size);
 813
 814         if (!unmapped_buf_allowed)
 815                 gbflags &= ~GB_UNMAPPED;
 816
 817         bo = &vp->v_bufobj;
 818         while (len > 0) {
 819                 /*
 820                  * If the buffer is not delayed-write (i.e. dirty), or it
 821                  * is delayed-write but either locked or inval, it cannot
 822                  * partake in the clustered write.
 823                  */
 824                 BO_LOCK(bo);
 825                 if ((tbp = gbincore(&vp->v_bufobj, start_lbn)) == NULL ||
 826                     (tbp->b_vflags & BV_BKGRDINPROG)) {
 827                         BO_UNLOCK(bo);
 828                         ++start_lbn;
 829                         --len;
 830                         continue;
 831                 }
 832                 if (BUF_LOCK(tbp,
 833                     LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, BO_LOCKPTR(bo))) {
 834                         ++start_lbn;
 835                         --len;
 836                         continue;
 837                 }
 838                 if ((tbp->b_flags & (B_INVAL | B_DELWRI)) != B_DELWRI) {
 839                         BUF_UNLOCK(tbp);
 840                         ++start_lbn;
 841                         --len;
 842                         continue;
 843                 }
 844                 bremfree(tbp);
 845                 tbp->b_flags &= ~B_DONE;
 846
 847                 /*
 848                  * Extra memory in the buffer, punt on this buffer.
 849                  * XXX we could handle this in most cases, but we would
 850                  * have to push the extra memory down to after our max
 851                  * possible cluster size and then potentially pull it back
 852                  * up if the cluster was terminated prematurely--too much
 853                  * hassle.
 854                  */
 855                 if (((tbp->b_flags & (B_CLUSTEROK | B_MALLOC | B_VMIO)) !=
 856                      (B_CLUSTEROK | B_VMIO)) ||
 857                   (tbp->b_bcount != tbp->b_bufsize) ||
 858                   (tbp->b_bcount != size) ||
 859                   (len == 1) ||
 860                   ((bp = uma_zalloc(cluster_pbuf_zone, M_NOWAIT)) == NULL)) {
 861                         totalwritten += tbp->b_bufsize;
 862                         bawrite(tbp);
 863                         ++start_lbn;
 864                         --len;
 865                         continue;
 866                 }
 867                 MPASS((bp->b_flags & B_MAXPHYS) != 0);
 868
 869                 /*
 870                  * We got a pbuf to make the cluster in.
 871                  * so initialise it.
 872                  */
 873                 TAILQ_INIT(&bp->b_cluster.cluster_head);
 874                 bp->b_bcount = 0;
 875                 bp->b_bufsize = 0;
 876                 bp->b_npages = 0;
 877                 if (tbp->b_wcred != NOCRED)
 878                         bp->b_wcred = crhold(tbp->b_wcred);
 879
 880                 bp->b_blkno = tbp->b_blkno;
 881                 bp->b_lblkno = tbp->b_lblkno;
 882                 bp->b_offset = tbp->b_offset;
 883
 884                 /*
 885                  * We are synthesizing a buffer out of vm_page_t's, but
 886                  * if the block size is not page aligned then the starting
 887                  * address may not be either.  Inherit the b_data offset
 888                  * from the original buffer.
 889                  */
 890                 if ((gbflags & GB_UNMAPPED) == 0 ||
 891                     (tbp->b_flags & B_VMIO) == 0) {
 892                         bp->b_data = (char *)((vm_offset_t)bp->b_data |
 893                             ((vm_offset_t)tbp->b_data & PAGE_MASK));
 894                 } else {
 895                         bp->b_data = unmapped_buf;
 896                 }
 897                 bp->b_flags |= B_CLUSTER | (tbp->b_flags & (B_VMIO |
 898                     B_NEEDCOMMIT));
 899                 bp->b_iodone = cluster_callback;
 900                 pbgetvp(vp, bp);
 901                 /*
 902                  * From this location in the file, scan forward to see
 903                  * if there are buffers with adjacent data that need to
 904                  * be written as well.
 905                  */
 906                 for (i = 0; i < len; ++i, ++start_lbn) {
 907                         if (i != 0) { /* If not the first buffer */
 908                                 /*
 909                                  * If the adjacent data is not even in core it
 910                                  * can't need to be written.
 911                                  */
 912                                 BO_LOCK(bo);
 913                                 if ((tbp = gbincore(bo, start_lbn)) == NULL ||
 914                                     (tbp->b_vflags & BV_BKGRDINPROG)) {
 915                                         BO_UNLOCK(bo);
 916                                         break;
 917                                 }
 918
 919                                 /*
 920                                  * If it IS in core, but has different
 921                                  * characteristics, or is locked (which
 922                                  * means it could be undergoing a background
 923                                  * I/O or be in a weird state), then don't
 924                                  * cluster with it.
 925                                  */
 926                                 if (BUF_LOCK(tbp,
 927                                     LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK,
 928                                     BO_LOCKPTR(bo)))
 929                                         break;
 930
 931                                 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK |
 932                                     B_INVAL | B_DELWRI | B_NEEDCOMMIT))
 933                                     != (B_DELWRI | B_CLUSTEROK |
 934                                     (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) ||
 935                                     tbp->b_wcred != bp->b_wcred) {
 936                                         BUF_UNLOCK(tbp);
 937                                         break;
 938                                 }
 939
 940                                 /*
 941                                  * Check that the combined cluster
 942                                  * would make sense with regard to pages
 943                                  * and would not be too large
 944                                  */
 945                                 if ((tbp->b_bcount != size) ||
 946                                   ((bp->b_blkno + (dbsize * i)) !=
 947                                     tbp->b_blkno) ||
 948                                   ((tbp->b_npages + bp->b_npages) >
 949                                     (vp->v_mount->mnt_iosize_max / PAGE_SIZE))) {
 950                                         BUF_UNLOCK(tbp);
 951                                         break;
 952                                 }
 953
 954                                 /*
 955                                  * Ok, it's passed all the tests,
 956                                  * so remove it from the free list
 957                                  * and mark it busy. We will use it.
 958                                  */
 959                                 bremfree(tbp);
 960                                 tbp->b_flags &= ~B_DONE;
 961                         } /* end of code for non-first buffers only */
 962                         /*
 963                          * If the IO is via the VM then we do some
 964                          * special VM hackery (yuck).  Since the buffer's
 965                          * block size may not be page-aligned it is possible
 966                          * for a page to be shared between two buffers.  We
 967                          * have to get rid of the duplication when building
 968                          * the cluster.
 969                          */
 970                         if (tbp->b_flags & B_VMIO) {
 971                                 vm_page_t m;
 972
 973                                 if (i == 0) {
 974                                         vfs_busy_pages_acquire(tbp);
 975                                 } else { /* if not first buffer */
 976                                         for (j = 0; j < tbp->b_npages; j += 1) {
 977                                                 m = tbp->b_pages[j];
 978                                                 if (vm_page_trysbusy(m) == 0) {
 979                                                         for (j--; j >= 0; j--)
 980                                                                 vm_page_sunbusy(
 981                                                                     tbp->b_pages[j]);
 982                                                         bqrelse(tbp);
 983                                                         goto finishcluster;
 984                                                 }
 985                                         }
 986                                 }
 987                                 vm_object_pip_add(tbp->b_bufobj->bo_object,
 988                                     tbp->b_npages);
 989                                 for (j = 0; j < tbp->b_npages; j += 1) {
 990                                         m = tbp->b_pages[j];
 991                                         if ((bp->b_npages == 0) ||
 992                                           (bp->b_pages[bp->b_npages - 1] != m)) {
 993                                                 bp->b_pages[bp->b_npages] = m;
 994                                                 bp->b_npages++;
 995                                         }
 996                                 }
 997                         }
 998                         bp->b_bcount += size;
 999                         bp->b_bufsize += size;
1000                         /*
1001                          * If any of the clustered buffers have their
1002                          * B_BARRIER flag set, transfer that request to
1003                          * the cluster.
1004                          */
1005                         bp->b_flags |= (tbp->b_flags & B_BARRIER);
1006                         tbp->b_flags &= ~(B_DONE | B_BARRIER);
1007                         tbp->b_flags |= B_ASYNC;
1008                         tbp->b_ioflags &= ~BIO_ERROR;
1009                         tbp->b_iocmd = BIO_WRITE;
1010                         bundirty(tbp);
1011                         reassignbuf(tbp);               /* put on clean list */
1012                         bufobj_wref(tbp->b_bufobj);
1013                         BUF_KERNPROC(tbp);
1014                         buf_track(tbp, __func__);
1015                         TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head,
1016                                 tbp, b_cluster.cluster_entry);
1017                 }
1018         finishcluster:
1019                 if (buf_mapped(bp)) {
1020                         pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
1021                             (vm_page_t *)bp->b_pages, bp->b_npages);
1022                 }
1023                 if (bp->b_bufsize > bp->b_kvasize)
1024                         panic(
1025                             "cluster_wbuild: b_bufsize(%ld) > b_kvasize(%d)\n",
1026                             bp->b_bufsize, bp->b_kvasize);
1027                 totalwritten += bp->b_bufsize;
1028                 bp->b_dirtyoff = 0;
1029                 bp->b_dirtyend = bp->b_bufsize;
1030                 bawrite(bp);
1031
1032                 len -= i;
1033         }
1034         return totalwritten;
1035 }
1036
1037 /*
1038  * Collect together all the buffers in a cluster.
1039  * Plus add one additional buffer.
1040  */
1041 static struct cluster_save *
1042 cluster_collectbufs(struct vnode *vp, struct buf *last_bp, int gbflags)
1043 {
1044         struct cluster_save *buflist;
1045         struct buf *bp;
1046         daddr_t lbn;
1047         int i, j, len, error;
1048
1049         len = vp->v_lastw - vp->v_cstart + 1;
1050         buflist = malloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist),
1051             M_SEGMENT, M_WAITOK);
1052         buflist->bs_nchildren = 0;
1053         buflist->bs_children = (struct buf **) (buflist + 1);
1054         for (lbn = vp->v_cstart, i = 0; i < len; lbn++, i++) {
1055                 error = bread_gb(vp, lbn, last_bp->b_bcount, NOCRED,
1056                     gbflags, &bp);
1057                 if (error != 0) {
1058                         /*
1059                          * If read fails, release collected buffers
1060                          * and return failure.
1061                          */
1062                         for (j = 0; j < i; j++)
1063                                 brelse(buflist->bs_children[j]);
1064                         free(buflist, M_SEGMENT);
1065                         return (NULL);
1066                 }
1067                 buflist->bs_children[i] = bp;
1068                 if (bp->b_blkno == bp->b_lblkno)
1069                         VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno,
1070                                 NULL, NULL);
1071         }
1072         buflist->bs_children[i] = bp = last_bp;
1073         if (bp->b_blkno == bp->b_lblkno)
1074                 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
1075         buflist->bs_nchildren = i + 1;
1076         return (buflist);
1077 }