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 "opt_debug_cluster.h"
  40
  41 #include <sys/param.h>
  42 #include <sys/systm.h>
  43 #include <sys/kernel.h>
  44 #include <sys/proc.h>
  45 #include <sys/bio.h>
  46 #include <sys/buf.h>
  47 #include <sys/vnode.h>
  48 #include <sys/malloc.h>
  49 #include <sys/mount.h>
  50 #include <sys/racct.h>
  51 #include <sys/resourcevar.h>
  52 #include <sys/rwlock.h>
  53 #include <sys/vmmeter.h>
  54 #include <vm/vm.h>
  55 #include <vm/vm_object.h>
  56 #include <vm/vm_page.h>
  57 #include <sys/sysctl.h>
  58
  59 #if defined(CLUSTERDEBUG)
  60 static int      rcluster= 0;
  61 SYSCTL_INT(_debug, OID_AUTO, rcluster, CTLFLAG_RW, &rcluster, 0,
  62     "Debug VFS clustering code");
  63 #endif
  64
  65 static MALLOC_DEFINE(M_SEGMENT, "cl_savebuf", "cluster_save buffer");
  66 static uma_zone_t cluster_pbuf_zone;
  67
  68 static void cluster_init(void *);
  69 static struct cluster_save *cluster_collectbufs(struct vnode *vp,
  70             struct buf *last_bp, int gbflags);
  71 static struct buf *cluster_rbuild(struct vnode *vp, u_quad_t filesize,
  72             daddr_t lbn, daddr_t blkno, long size, int run, int gbflags,
  73             struct buf *fbp);
  74 static void cluster_callback(struct buf *);
  75
  76 static int write_behind = 1;
  77 SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0,
  78     "Cluster write-behind; 0: disable, 1: enable, 2: backed off");
  79
  80 static int read_max = 64;
  81 SYSCTL_INT(_vfs, OID_AUTO, read_max, CTLFLAG_RW, &read_max, 0,
  82     "Cluster read-ahead max block count");
  83
  84 static int read_min = 1;
  85 SYSCTL_INT(_vfs, OID_AUTO, read_min, CTLFLAG_RW, &read_min, 0,
  86     "Cluster read min block count");
  87
  88 SYSINIT(cluster, SI_SUB_CPU, SI_ORDER_ANY, cluster_init, NULL);
  89
  90 static void
  91 cluster_init(void *dummy)
  92 {
  93
  94         cluster_pbuf_zone = pbuf_zsecond_create("clpbuf", nswbuf / 2);
  95 }
  96
  97 /*
  98  * Read data to a buf, including read-ahead if we find this to be beneficial.
  99  * cluster_read replaces bread.
 100  */
 101 int
 102 cluster_read(struct vnode *vp, u_quad_t filesize, daddr_t lblkno, long size,
 103     struct ucred *cred, long totread, int seqcount, int gbflags,
 104     struct buf **bpp)
 105 {
 106         struct buf *bp, *rbp, *reqbp;
 107         struct bufobj *bo;
 108         struct thread *td;
 109         daddr_t blkno, origblkno;
 110         int maxra, racluster;
 111         int error, ncontig;
 112         int i;
 113
 114         error = 0;
 115         td = curthread;
 116         bo = &vp->v_bufobj;
 117         if (!unmapped_buf_allowed)
 118                 gbflags &= ~GB_UNMAPPED;
 119
 120         /*
 121          * Try to limit the amount of read-ahead by a few
 122          * ad-hoc parameters.  This needs work!!!
 123          */
 124         racluster = vp->v_mount->mnt_iosize_max / size;
 125         maxra = seqcount;
 126         maxra = min(read_max, maxra);
 127         maxra = min(nbuf/8, maxra);
 128         if (((u_quad_t)(lblkno + maxra + 1) * size) > filesize)
 129                 maxra = (filesize / size) - lblkno;
 130
 131         /*
 132          * get the requested block
 133          */
 134         error = getblkx(vp, lblkno, size, 0, 0, gbflags, &bp);
 135         if (error != 0) {
 136                 *bpp = NULL;
 137                 return (error);
 138         }
 139         gbflags &= ~GB_NOSPARSE;
 140         origblkno = lblkno;
 141         *bpp = reqbp = bp;
 142
 143         /*
 144          * if it is in the cache, then check to see if the reads have been
 145          * sequential.  If they have, then try some read-ahead, otherwise
 146          * back-off on prospective read-aheads.
 147          */
 148         if (bp->b_flags & B_CACHE) {
 149                 if (!seqcount) {
 150                         return 0;
 151                 } else if ((bp->b_flags & B_RAM) == 0) {
 152                         return 0;
 153                 } else {
 154                         bp->b_flags &= ~B_RAM;
 155                         BO_RLOCK(bo);
 156                         for (i = 1; i < maxra; i++) {
 157                                 /*
 158                                  * Stop if the buffer does not exist or it
 159                                  * is invalid (about to go away?)
 160                                  */
 161                                 rbp = gbincore(&vp->v_bufobj, lblkno+i);
 162                                 if (rbp == NULL || (rbp->b_flags & B_INVAL))
 163                                         break;
 164
 165                                 /*
 166                                  * Set another read-ahead mark so we know
 167                                  * to check again. (If we can lock the
 168                                  * buffer without waiting)
 169                                  */
 170                                 if ((((i % racluster) == (racluster - 1)) ||
 171                                     (i == (maxra - 1)))
 172                                     && (0 == BUF_LOCK(rbp,
 173                                         LK_EXCLUSIVE | LK_NOWAIT, NULL))) {
 174                                         rbp->b_flags |= B_RAM;
 175                                         BUF_UNLOCK(rbp);
 176                                 }
 177                         }
 178                         BO_RUNLOCK(bo);
 179                         if (i >= maxra) {
 180                                 return 0;
 181                         }
 182                         lblkno += i;
 183                 }
 184                 reqbp = bp = NULL;
 185         /*
 186          * If it isn't in the cache, then get a chunk from
 187          * disk if sequential, otherwise just get the block.
 188          */
 189         } else {
 190                 off_t firstread = bp->b_offset;
 191                 int nblks;
 192                 long minread;
 193
 194                 KASSERT(bp->b_offset != NOOFFSET,
 195                     ("cluster_read: no buffer offset"));
 196
 197                 ncontig = 0;
 198
 199                 /*
 200                  * Adjust totread if needed
 201                  */
 202                 minread = read_min * size;
 203                 if (minread > totread)
 204                         totread = minread;
 205
 206                 /*
 207                  * Compute the total number of blocks that we should read
 208                  * synchronously.
 209                  */
 210                 if (firstread + totread > filesize)
 211                         totread = filesize - firstread;
 212                 nblks = howmany(totread, size);
 213                 if (nblks > racluster)
 214                         nblks = racluster;
 215
 216                 /*
 217                  * Now compute the number of contiguous blocks.
 218                  */
 219                 if (nblks > 1) {
 220                         error = VOP_BMAP(vp, lblkno, NULL,
 221                                 &blkno, &ncontig, NULL);
 222                         /*
 223                          * If this failed to map just do the original block.
 224                          */
 225                         if (error || blkno == -1)
 226                                 ncontig = 0;
 227                 }
 228
 229                 /*
 230                  * If we have contiguous data available do a cluster
 231                  * otherwise just read the requested block.
 232                  */
 233                 if (ncontig) {
 234                         /* Account for our first block. */
 235                         ncontig = min(ncontig + 1, nblks);
 236                         if (ncontig < nblks)
 237                                 nblks = ncontig;
 238                         bp = cluster_rbuild(vp, filesize, lblkno,
 239                             blkno, size, nblks, gbflags, bp);
 240                         lblkno += (bp->b_bufsize / size);
 241                 } else {
 242                         bp->b_flags |= B_RAM;
 243                         bp->b_iocmd = BIO_READ;
 244                         lblkno += 1;
 245                 }
 246         }
 247
 248         /*
 249          * handle the synchronous read so that it is available ASAP.
 250          */
 251         if (bp) {
 252                 if ((bp->b_flags & B_CLUSTER) == 0) {
 253                         vfs_busy_pages(bp, 0);
 254                 }
 255                 bp->b_flags &= ~B_INVAL;
 256                 bp->b_ioflags &= ~BIO_ERROR;
 257                 if ((bp->b_flags & B_ASYNC) || bp->b_iodone != NULL)
 258                         BUF_KERNPROC(bp);
 259                 bp->b_iooffset = dbtob(bp->b_blkno);
 260                 bstrategy(bp);
 261 #ifdef RACCT
 262                 if (racct_enable) {
 263                         PROC_LOCK(td->td_proc);
 264                         racct_add_buf(td->td_proc, bp, 0);
 265                         PROC_UNLOCK(td->td_proc);
 266                 }
 267 #endif /* RACCT */
 268                 td->td_ru.ru_inblock++;
 269         }
 270
 271         /*
 272          * If we have been doing sequential I/O, then do some read-ahead.
 273          */
 274         while (lblkno < (origblkno + maxra)) {
 275                 error = VOP_BMAP(vp, lblkno, NULL, &blkno, &ncontig, NULL);
 276                 if (error)
 277                         break;
 278
 279                 if (blkno == -1)
 280                         break;
 281
 282                 /*
 283                  * We could throttle ncontig here by maxra but we might as
 284                  * well read the data if it is contiguous.  We're throttled
 285                  * by racluster anyway.
 286                  */
 287                 if (ncontig) {
 288                         ncontig = min(ncontig + 1, racluster);
 289                         rbp = cluster_rbuild(vp, filesize, lblkno, blkno,
 290                             size, ncontig, gbflags, NULL);
 291                         lblkno += (rbp->b_bufsize / size);
 292                         if (rbp->b_flags & B_DELWRI) {
 293                                 bqrelse(rbp);
 294                                 continue;
 295                         }
 296                 } else {
 297                         rbp = getblk(vp, lblkno, size, 0, 0, gbflags);
 298                         lblkno += 1;
 299                         if (rbp->b_flags & B_DELWRI) {
 300                                 bqrelse(rbp);
 301                                 continue;
 302                         }
 303                         rbp->b_flags |= B_ASYNC | B_RAM;
 304                         rbp->b_iocmd = BIO_READ;
 305                         rbp->b_blkno = blkno;
 306                 }
 307                 if (rbp->b_flags & B_CACHE) {
 308                         rbp->b_flags &= ~B_ASYNC;
 309                         bqrelse(rbp);
 310                         continue;
 311                 }
 312                 if ((rbp->b_flags & B_CLUSTER) == 0) {
 313                         vfs_busy_pages(rbp, 0);
 314                 }
 315                 rbp->b_flags &= ~B_INVAL;
 316                 rbp->b_ioflags &= ~BIO_ERROR;
 317                 if ((rbp->b_flags & B_ASYNC) || rbp->b_iodone != NULL)
 318                         BUF_KERNPROC(rbp);
 319                 rbp->b_iooffset = dbtob(rbp->b_blkno);
 320                 bstrategy(rbp);
 321 #ifdef RACCT
 322                 if (racct_enable) {
 323                         PROC_LOCK(td->td_proc);
 324                         racct_add_buf(td->td_proc, rbp, 0);
 325                         PROC_UNLOCK(td->td_proc);
 326                 }
 327 #endif /* RACCT */
 328                 td->td_ru.ru_inblock++;
 329         }
 330
 331         if (reqbp) {
 332                 /*
 333                  * Like bread, always brelse() the buffer when
 334                  * returning an error.
 335                  */
 336                 error = bufwait(reqbp);
 337                 if (error != 0) {
 338                         brelse(reqbp);
 339                         *bpp = NULL;
 340                 }
 341         }
 342         return (error);
 343 }
 344
 345 /*
 346  * If blocks are contiguous on disk, use this to provide clustered
 347  * read ahead.  We will read as many blocks as possible sequentially
 348  * and then parcel them up into logical blocks in the buffer hash table.
 349  */
 350 static struct buf *
 351 cluster_rbuild(struct vnode *vp, u_quad_t filesize, daddr_t lbn,
 352     daddr_t blkno, long size, int run, int gbflags, struct buf *fbp)
 353 {
 354         struct buf *bp, *tbp;
 355         daddr_t bn;
 356         off_t off;
 357         long tinc, tsize;
 358         int i, inc, j, k, toff;
 359
 360         KASSERT(size == vp->v_mount->mnt_stat.f_iosize,
 361             ("cluster_rbuild: size %ld != f_iosize %jd\n",
 362             size, (intmax_t)vp->v_mount->mnt_stat.f_iosize));
 363
 364         /*
 365          * avoid a division
 366          */
 367         while ((u_quad_t) size * (lbn + run) > filesize) {
 368                 --run;
 369         }
 370
 371         if (fbp) {
 372                 tbp = fbp;
 373                 tbp->b_iocmd = BIO_READ;
 374         } else {
 375                 tbp = getblk(vp, lbn, size, 0, 0, gbflags);
 376                 if (tbp->b_flags & B_CACHE)
 377                         return tbp;
 378                 tbp->b_flags |= B_ASYNC | B_RAM;
 379                 tbp->b_iocmd = BIO_READ;
 380         }
 381         tbp->b_blkno = blkno;
 382         if( (tbp->b_flags & B_MALLOC) ||
 383                 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1) )
 384                 return tbp;
 385
 386         bp = uma_zalloc(cluster_pbuf_zone, M_NOWAIT);
 387         if (bp == NULL)
 388                 return tbp;
 389
 390         /*
 391          * We are synthesizing a buffer out of vm_page_t's, but
 392          * if the block size is not page aligned then the starting
 393          * address may not be either.  Inherit the b_data offset
 394          * from the original buffer.
 395          */
 396         bp->b_flags = B_ASYNC | B_CLUSTER | B_VMIO;
 397         if ((gbflags & GB_UNMAPPED) != 0) {
 398                 bp->b_data = unmapped_buf;
 399         } else {
 400                 bp->b_data = (char *)((vm_offset_t)bp->b_data |
 401                     ((vm_offset_t)tbp->b_data & PAGE_MASK));
 402         }
 403         bp->b_iocmd = BIO_READ;
 404         bp->b_iodone = cluster_callback;
 405         bp->b_blkno = blkno;
 406         bp->b_lblkno = lbn;
 407         bp->b_offset = tbp->b_offset;
 408         KASSERT(bp->b_offset != NOOFFSET, ("cluster_rbuild: no buffer offset"));
 409         pbgetvp(vp, bp);
 410
 411         TAILQ_INIT(&bp->b_cluster.cluster_head);
 412
 413         bp->b_bcount = 0;
 414         bp->b_bufsize = 0;
 415         bp->b_npages = 0;
 416
 417         inc = btodb(size);
 418         for (bn = blkno, i = 0; i < run; ++i, bn += inc) {
 419                 if (i == 0) {
 420                         VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object);
 421                         vfs_drain_busy_pages(tbp);
 422                         vm_object_pip_add(tbp->b_bufobj->bo_object,
 423                             tbp->b_npages);
 424                         for (k = 0; k < tbp->b_npages; k++)
 425                                 vm_page_sbusy(tbp->b_pages[k]);
 426                         VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object);
 427                 } else {
 428                         if ((bp->b_npages * PAGE_SIZE) +
 429                             round_page(size) > vp->v_mount->mnt_iosize_max) {
 430                                 break;
 431                         }
 432
 433                         tbp = getblk(vp, lbn + i, size, 0, 0, GB_LOCK_NOWAIT |
 434                             (gbflags & GB_UNMAPPED));
 435
 436                         /* Don't wait around for locked bufs. */
 437                         if (tbp == NULL)
 438                                 break;
 439
 440                         /*
 441                          * Stop scanning if the buffer is fully valid
 442                          * (marked B_CACHE), or locked (may be doing a
 443                          * background write), or if the buffer is not
 444                          * VMIO backed.  The clustering code can only deal
 445                          * with VMIO-backed buffers.  The bo lock is not
 446                          * required for the BKGRDINPROG check since it
 447                          * can not be set without the buf lock.
 448                          */
 449                         if ((tbp->b_vflags & BV_BKGRDINPROG) ||
 450                             (tbp->b_flags & B_CACHE) ||
 451                             (tbp->b_flags & B_VMIO) == 0) {
 452                                 bqrelse(tbp);
 453                                 break;
 454                         }
 455
 456                         /*
 457                          * The buffer must be completely invalid in order to
 458                          * take part in the cluster.  If it is partially valid
 459                          * then we stop.
 460                          */
 461                         off = tbp->b_offset;
 462                         tsize = size;
 463                         VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object);
 464                         for (j = 0; tsize > 0; j++) {
 465                                 toff = off & PAGE_MASK;
 466                                 tinc = tsize;
 467                                 if (toff + tinc > PAGE_SIZE)
 468                                         tinc = PAGE_SIZE - toff;
 469                                 VM_OBJECT_ASSERT_WLOCKED(tbp->b_pages[j]->object);
 470                                 if ((tbp->b_pages[j]->valid &
 471                                     vm_page_bits(toff, tinc)) != 0)
 472                                         break;
 473                                 if (vm_page_xbusied(tbp->b_pages[j]))
 474                                         break;
 475                                 vm_object_pip_add(tbp->b_bufobj->bo_object, 1);
 476                                 vm_page_sbusy(tbp->b_pages[j]);
 477                                 off += tinc;
 478                                 tsize -= tinc;
 479                         }
 480                         if (tsize > 0) {
 481 clean_sbusy:
 482                                 vm_object_pip_wakeupn(tbp->b_bufobj->bo_object,
 483                                     j);
 484                                 for (k = 0; k < j; k++)
 485                                         vm_page_sunbusy(tbp->b_pages[k]);
 486                                 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object);
 487                                 bqrelse(tbp);
 488                                 break;
 489                         }
 490                         VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object);
 491
 492                         /*
 493                          * Set a read-ahead mark as appropriate
 494                          */
 495                         if ((fbp && (i == 1)) || (i == (run - 1)))
 496                                 tbp->b_flags |= B_RAM;
 497
 498                         /*
 499                          * Set the buffer up for an async read (XXX should
 500                          * we do this only if we do not wind up brelse()ing?).
 501                          * Set the block number if it isn't set, otherwise
 502                          * if it is make sure it matches the block number we
 503                          * expect.
 504                          */
 505                         tbp->b_flags |= B_ASYNC;
 506                         tbp->b_iocmd = BIO_READ;
 507                         if (tbp->b_blkno == tbp->b_lblkno) {
 508                                 tbp->b_blkno = bn;
 509                         } else if (tbp->b_blkno != bn) {
 510                                 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object);
 511                                 goto clean_sbusy;
 512                         }
 513                 }
 514                 /*
 515                  * XXX fbp from caller may not be B_ASYNC, but we are going
 516                  * to biodone() it in cluster_callback() anyway
 517                  */
 518                 BUF_KERNPROC(tbp);
 519                 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head,
 520                         tbp, b_cluster.cluster_entry);
 521                 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object);
 522                 for (j = 0; j < tbp->b_npages; j += 1) {
 523                         vm_page_t m;
 524                         m = tbp->b_pages[j];
 525                         if ((bp->b_npages == 0) ||
 526                             (bp->b_pages[bp->b_npages-1] != m)) {
 527                                 bp->b_pages[bp->b_npages] = m;
 528                                 bp->b_npages++;
 529                         }
 530                         if (m->valid == VM_PAGE_BITS_ALL)
 531                                 tbp->b_pages[j] = bogus_page;
 532                 }
 533                 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object);
 534                 /*
 535                  * Don't inherit tbp->b_bufsize as it may be larger due to
 536                  * a non-page-aligned size.  Instead just aggregate using
 537                  * 'size'.
 538                  */
 539                 if (tbp->b_bcount != size)
 540                         printf("warning: tbp->b_bcount wrong %ld vs %ld\n", tbp->b_bcount, size);
 541                 if (tbp->b_bufsize != size)
 542                         printf("warning: tbp->b_bufsize wrong %ld vs %ld\n", tbp->b_bufsize, size);
 543                 bp->b_bcount += size;
 544                 bp->b_bufsize += size;
 545         }
 546
 547         /*
 548          * Fully valid pages in the cluster are already good and do not need
 549          * to be re-read from disk.  Replace the page with bogus_page
 550          */
 551         VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
 552         for (j = 0; j < bp->b_npages; j++) {
 553                 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[j]->object);
 554                 if (bp->b_pages[j]->valid == VM_PAGE_BITS_ALL)
 555                         bp->b_pages[j] = bogus_page;
 556         }
 557         VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
 558         if (bp->b_bufsize > bp->b_kvasize)
 559                 panic("cluster_rbuild: b_bufsize(%ld) > b_kvasize(%d)\n",
 560                     bp->b_bufsize, bp->b_kvasize);
 561
 562         if (buf_mapped(bp)) {
 563                 pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
 564                     (vm_page_t *)bp->b_pages, bp->b_npages);
 565         }
 566         return (bp);
 567 }
 568
 569 /*
 570  * Cleanup after a clustered read or write.
 571  * This is complicated by the fact that any of the buffers might have
 572  * extra memory (if there were no empty buffer headers at allocbuf time)
 573  * that we will need to shift around.
 574  */
 575 static void
 576 cluster_callback(struct buf *bp)
 577 {
 578         struct buf *nbp, *tbp;
 579         int error = 0;
 580
 581         /*
 582          * Must propagate errors to all the components.
 583          */
 584         if (bp->b_ioflags & BIO_ERROR)
 585                 error = bp->b_error;
 586
 587         if (buf_mapped(bp)) {
 588                 pmap_qremove(trunc_page((vm_offset_t) bp->b_data),
 589                     bp->b_npages);
 590         }
 591         /*
 592          * Move memory from the large cluster buffer into the component
 593          * buffers and mark IO as done on these.
 594          */
 595         for (tbp = TAILQ_FIRST(&bp->b_cluster.cluster_head);
 596                 tbp; tbp = nbp) {
 597                 nbp = TAILQ_NEXT(&tbp->b_cluster, cluster_entry);
 598                 if (error) {
 599                         tbp->b_ioflags |= BIO_ERROR;
 600                         tbp->b_error = error;
 601                 } else {
 602                         tbp->b_dirtyoff = tbp->b_dirtyend = 0;
 603                         tbp->b_flags &= ~B_INVAL;
 604                         tbp->b_ioflags &= ~BIO_ERROR;
 605                         /*
 606                          * XXX the bdwrite()/bqrelse() issued during
 607                          * cluster building clears B_RELBUF (see bqrelse()
 608                          * comment).  If direct I/O was specified, we have
 609                          * to restore it here to allow the buffer and VM
 610                          * to be freed.
 611                          */
 612                         if (tbp->b_flags & B_DIRECT)
 613                                 tbp->b_flags |= B_RELBUF;
 614                 }
 615                 bufdone(tbp);
 616         }
 617         pbrelvp(bp);
 618         uma_zfree(cluster_pbuf_zone, bp);
 619 }
 620
 621 /*
 622  *      cluster_wbuild_wb:
 623  *
 624  *      Implement modified write build for cluster.
 625  *
 626  *              write_behind = 0        write behind disabled
 627  *              write_behind = 1        write behind normal (default)
 628  *              write_behind = 2        write behind backed-off
 629  */
 630
 631 static __inline int
 632 cluster_wbuild_wb(struct vnode *vp, long size, daddr_t start_lbn, int len,
 633     int gbflags)
 634 {
 635         int r = 0;
 636
 637         switch (write_behind) {
 638         case 2:
 639                 if (start_lbn < len)
 640                         break;
 641                 start_lbn -= len;
 642                 /* FALLTHROUGH */
 643         case 1:
 644                 r = cluster_wbuild(vp, size, start_lbn, len, gbflags);
 645                 /* FALLTHROUGH */
 646         default:
 647                 /* FALLTHROUGH */
 648                 break;
 649         }
 650         return(r);
 651 }
 652
 653 /*
 654  * Do clustered write for FFS.
 655  *
 656  * Three cases:
 657  *      1. Write is not sequential (write asynchronously)
 658  *      Write is sequential:
 659  *      2.      beginning of cluster - begin cluster
 660  *      3.      middle of a cluster - add to cluster
 661  *      4.      end of a cluster - asynchronously write cluster
 662  */
 663 void
 664 cluster_write(struct vnode *vp, struct buf *bp, u_quad_t filesize, int seqcount,
 665     int gbflags)
 666 {
 667         daddr_t lbn;
 668         int maxclen, cursize;
 669         int lblocksize;
 670         int async;
 671
 672         if (!unmapped_buf_allowed)
 673                 gbflags &= ~GB_UNMAPPED;
 674
 675         if (vp->v_type == VREG) {
 676                 async = DOINGASYNC(vp);
 677                 lblocksize = vp->v_mount->mnt_stat.f_iosize;
 678         } else {
 679                 async = 0;
 680                 lblocksize = bp->b_bufsize;
 681         }
 682         lbn = bp->b_lblkno;
 683         KASSERT(bp->b_offset != NOOFFSET, ("cluster_write: no buffer offset"));
 684
 685         /* Initialize vnode to beginning of file. */
 686         if (lbn == 0)
 687                 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0;
 688
 689         if (vp->v_clen == 0 || lbn != vp->v_lastw + 1 ||
 690             (bp->b_blkno != vp->v_lasta + btodb(lblocksize))) {
 691                 maxclen = vp->v_mount->mnt_iosize_max / lblocksize - 1;
 692                 if (vp->v_clen != 0) {
 693                         /*
 694                          * Next block is not sequential.
 695                          *
 696                          * If we are not writing at end of file, the process
 697                          * seeked to another point in the file since its last
 698                          * write, or we have reached our maximum cluster size,
 699                          * then push the previous cluster. Otherwise try
 700                          * reallocating to make it sequential.
 701                          *
 702                          * Change to algorithm: only push previous cluster if
 703                          * it was sequential from the point of view of the
 704                          * seqcount heuristic, otherwise leave the buffer
 705                          * intact so we can potentially optimize the I/O
 706                          * later on in the buf_daemon or update daemon
 707                          * flush.
 708                          */
 709                         cursize = vp->v_lastw - vp->v_cstart + 1;
 710                         if (((u_quad_t) bp->b_offset + lblocksize) != filesize ||
 711                             lbn != vp->v_lastw + 1 || vp->v_clen <= cursize) {
 712                                 if (!async && seqcount > 0) {
 713                                         cluster_wbuild_wb(vp, lblocksize,
 714                                             vp->v_cstart, cursize, gbflags);
 715                                 }
 716                         } else {
 717                                 struct buf **bpp, **endbp;
 718                                 struct cluster_save *buflist;
 719
 720                                 buflist = cluster_collectbufs(vp, bp, gbflags);
 721                                 if (buflist == NULL) {
 722                                         /*
 723                                          * Cluster build failed so just write
 724                                          * it now.
 725                                          */
 726                                         bawrite(bp);
 727                                         return;
 728                                 }
 729                                 endbp = &buflist->bs_children
 730                                     [buflist->bs_nchildren - 1];
 731                                 if (VOP_REALLOCBLKS(vp, buflist)) {
 732                                         /*
 733                                          * Failed, push the previous cluster
 734                                          * if *really* writing sequentially
 735                                          * in the logical file (seqcount > 1),
 736                                          * otherwise delay it in the hopes that
 737                                          * the low level disk driver can
 738                                          * optimize the write ordering.
 739                                          */
 740                                         for (bpp = buflist->bs_children;
 741                                              bpp < endbp; bpp++)
 742                                                 brelse(*bpp);
 743                                         free(buflist, M_SEGMENT);
 744                                         if (seqcount > 1) {
 745                                                 cluster_wbuild_wb(vp,
 746                                                     lblocksize, vp->v_cstart,
 747                                                     cursize, gbflags);
 748                                         }
 749                                 } else {
 750                                         /*
 751                                          * Succeeded, keep building cluster.
 752                                          */
 753                                         for (bpp = buflist->bs_children;
 754                                              bpp <= endbp; bpp++)
 755                                                 bdwrite(*bpp);
 756                                         free(buflist, M_SEGMENT);
 757                                         vp->v_lastw = lbn;
 758                                         vp->v_lasta = bp->b_blkno;
 759                                         return;
 760                                 }
 761                         }
 762                 }
 763                 /*
 764                  * Consider beginning a cluster. If at end of file, make
 765                  * cluster as large as possible, otherwise find size of
 766                  * existing cluster.
 767                  */
 768                 if ((vp->v_type == VREG) &&
 769                         ((u_quad_t) bp->b_offset + lblocksize) != filesize &&
 770                     (bp->b_blkno == bp->b_lblkno) &&
 771                     (VOP_BMAP(vp, lbn, NULL, &bp->b_blkno, &maxclen, NULL) ||
 772                      bp->b_blkno == -1)) {
 773                         bawrite(bp);
 774                         vp->v_clen = 0;
 775                         vp->v_lasta = bp->b_blkno;
 776                         vp->v_cstart = lbn + 1;
 777                         vp->v_lastw = lbn;
 778                         return;
 779                 }
 780                 vp->v_clen = maxclen;
 781                 if (!async && maxclen == 0) {   /* I/O not contiguous */
 782                         vp->v_cstart = lbn + 1;
 783                         bawrite(bp);
 784                 } else {        /* Wait for rest of cluster */
 785                         vp->v_cstart = lbn;
 786                         bdwrite(bp);
 787                 }
 788         } else if (lbn == vp->v_cstart + vp->v_clen) {
 789                 /*
 790                  * At end of cluster, write it out if seqcount tells us we
 791                  * are operating sequentially, otherwise let the buf or
 792                  * update daemon handle it.
 793                  */
 794                 bdwrite(bp);
 795                 if (seqcount > 1) {
 796                         cluster_wbuild_wb(vp, lblocksize, vp->v_cstart,
 797                             vp->v_clen + 1, gbflags);
 798                 }
 799                 vp->v_clen = 0;
 800                 vp->v_cstart = lbn + 1;
 801         } else if (vm_page_count_severe()) {
 802                 /*
 803                  * We are low on memory, get it going NOW
 804                  */
 805                 bawrite(bp);
 806         } else {
 807                 /*
 808                  * In the middle of a cluster, so just delay the I/O for now.
 809                  */
 810                 bdwrite(bp);
 811         }
 812         vp->v_lastw = lbn;
 813         vp->v_lasta = bp->b_blkno;
 814 }
 815
 816
 817 /*
 818  * This is an awful lot like cluster_rbuild...wish they could be combined.
 819  * The last lbn argument is the current block on which I/O is being
 820  * performed.  Check to see that it doesn't fall in the middle of
 821  * the current block (if last_bp == NULL).
 822  */
 823 int
 824 cluster_wbuild(struct vnode *vp, long size, daddr_t start_lbn, int len,
 825     int gbflags)
 826 {
 827         struct buf *bp, *tbp;
 828         struct bufobj *bo;
 829         int i, j;
 830         int totalwritten = 0;
 831         int dbsize = btodb(size);
 832
 833         if (!unmapped_buf_allowed)
 834                 gbflags &= ~GB_UNMAPPED;
 835
 836         bo = &vp->v_bufobj;
 837         while (len > 0) {
 838                 /*
 839                  * If the buffer is not delayed-write (i.e. dirty), or it
 840                  * is delayed-write but either locked or inval, it cannot
 841                  * partake in the clustered write.
 842                  */
 843                 BO_LOCK(bo);
 844                 if ((tbp = gbincore(&vp->v_bufobj, start_lbn)) == NULL ||
 845                     (tbp->b_vflags & BV_BKGRDINPROG)) {
 846                         BO_UNLOCK(bo);
 847                         ++start_lbn;
 848                         --len;
 849                         continue;
 850                 }
 851                 if (BUF_LOCK(tbp,
 852                     LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, BO_LOCKPTR(bo))) {
 853                         ++start_lbn;
 854                         --len;
 855                         continue;
 856                 }
 857                 if ((tbp->b_flags & (B_INVAL | B_DELWRI)) != B_DELWRI) {
 858                         BUF_UNLOCK(tbp);
 859                         ++start_lbn;
 860                         --len;
 861                         continue;
 862                 }
 863                 bremfree(tbp);
 864                 tbp->b_flags &= ~B_DONE;
 865
 866                 /*
 867                  * Extra memory in the buffer, punt on this buffer.
 868                  * XXX we could handle this in most cases, but we would
 869                  * have to push the extra memory down to after our max
 870                  * possible cluster size and then potentially pull it back
 871                  * up if the cluster was terminated prematurely--too much
 872                  * hassle.
 873                  */
 874                 if (((tbp->b_flags & (B_CLUSTEROK | B_MALLOC | B_VMIO)) !=
 875                      (B_CLUSTEROK | B_VMIO)) ||
 876                   (tbp->b_bcount != tbp->b_bufsize) ||
 877                   (tbp->b_bcount != size) ||
 878                   (len == 1) ||
 879                   ((bp = uma_zalloc(cluster_pbuf_zone,
 880                   (vp->v_vflag & VV_MD) != 0 ? M_NOWAIT : M_WAITOK)) == NULL)) {
 881                         totalwritten += tbp->b_bufsize;
 882                         bawrite(tbp);
 883                         ++start_lbn;
 884                         --len;
 885                         continue;
 886                 }
 887
 888                 /*
 889                  * We got a pbuf to make the cluster in.
 890                  * so initialise it.
 891                  */
 892                 TAILQ_INIT(&bp->b_cluster.cluster_head);
 893                 bp->b_bcount = 0;
 894                 bp->b_bufsize = 0;
 895                 bp->b_npages = 0;
 896                 if (tbp->b_wcred != NOCRED)
 897                         bp->b_wcred = crhold(tbp->b_wcred);
 898
 899                 bp->b_blkno = tbp->b_blkno;
 900                 bp->b_lblkno = tbp->b_lblkno;
 901                 bp->b_offset = tbp->b_offset;
 902
 903                 /*
 904                  * We are synthesizing a buffer out of vm_page_t's, but
 905                  * if the block size is not page aligned then the starting
 906                  * address may not be either.  Inherit the b_data offset
 907                  * from the original buffer.
 908                  */
 909                 if ((gbflags & GB_UNMAPPED) == 0 ||
 910                     (tbp->b_flags & B_VMIO) == 0) {
 911                         bp->b_data = (char *)((vm_offset_t)bp->b_data |
 912                             ((vm_offset_t)tbp->b_data & PAGE_MASK));
 913                 } else {
 914                         bp->b_data = unmapped_buf;
 915                 }
 916                 bp->b_flags |= B_CLUSTER | (tbp->b_flags & (B_VMIO |
 917                     B_NEEDCOMMIT));
 918                 bp->b_iodone = cluster_callback;
 919                 pbgetvp(vp, bp);
 920                 /*
 921                  * From this location in the file, scan forward to see
 922                  * if there are buffers with adjacent data that need to
 923                  * be written as well.
 924                  */
 925                 for (i = 0; i < len; ++i, ++start_lbn) {
 926                         if (i != 0) { /* If not the first buffer */
 927                                 /*
 928                                  * If the adjacent data is not even in core it
 929                                  * can't need to be written.
 930                                  */
 931                                 BO_LOCK(bo);
 932                                 if ((tbp = gbincore(bo, start_lbn)) == NULL ||
 933                                     (tbp->b_vflags & BV_BKGRDINPROG)) {
 934                                         BO_UNLOCK(bo);
 935                                         break;
 936                                 }
 937
 938                                 /*
 939                                  * If it IS in core, but has different
 940                                  * characteristics, or is locked (which
 941                                  * means it could be undergoing a background
 942                                  * I/O or be in a weird state), then don't
 943                                  * cluster with it.
 944                                  */
 945                                 if (BUF_LOCK(tbp,
 946                                     LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK,
 947                                     BO_LOCKPTR(bo)))
 948                                         break;
 949
 950                                 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK |
 951                                     B_INVAL | B_DELWRI | B_NEEDCOMMIT))
 952                                     != (B_DELWRI | B_CLUSTEROK |
 953                                     (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) ||
 954                                     tbp->b_wcred != bp->b_wcred) {
 955                                         BUF_UNLOCK(tbp);
 956                                         break;
 957                                 }
 958
 959                                 /*
 960                                  * Check that the combined cluster
 961                                  * would make sense with regard to pages
 962                                  * and would not be too large
 963                                  */
 964                                 if ((tbp->b_bcount != size) ||
 965                                   ((bp->b_blkno + (dbsize * i)) !=
 966                                     tbp->b_blkno) ||
 967                                   ((tbp->b_npages + bp->b_npages) >
 968                                     (vp->v_mount->mnt_iosize_max / PAGE_SIZE))) {
 969                                         BUF_UNLOCK(tbp);
 970                                         break;
 971                                 }
 972
 973                                 /*
 974                                  * Ok, it's passed all the tests,
 975                                  * so remove it from the free list
 976                                  * and mark it busy. We will use it.
 977                                  */
 978                                 bremfree(tbp);
 979                                 tbp->b_flags &= ~B_DONE;
 980                         } /* end of code for non-first buffers only */
 981                         /*
 982                          * If the IO is via the VM then we do some
 983                          * special VM hackery (yuck).  Since the buffer's
 984                          * block size may not be page-aligned it is possible
 985                          * for a page to be shared between two buffers.  We
 986                          * have to get rid of the duplication when building
 987                          * the cluster.
 988                          */
 989                         if (tbp->b_flags & B_VMIO) {
 990                                 vm_page_t m;
 991
 992                                 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object);
 993                                 if (i == 0) {
 994                                         vfs_drain_busy_pages(tbp);
 995                                 } else { /* if not first buffer */
 996                                         for (j = 0; j < tbp->b_npages; j += 1) {
 997                                                 m = tbp->b_pages[j];
 998                                                 if (vm_page_xbusied(m)) {
 999                                                         VM_OBJECT_WUNLOCK(
1000                                                             tbp->b_object);
1001                                                         bqrelse(tbp);
1002                                                         goto finishcluster;
1003                                                 }
1004                                         }
1005                                 }
1006                                 for (j = 0; j < tbp->b_npages; j += 1) {
1007                                         m = tbp->b_pages[j];
1008                                         vm_page_sbusy(m);
1009                                         vm_object_pip_add(m->object, 1);
1010                                         if ((bp->b_npages == 0) ||
1011                                           (bp->b_pages[bp->b_npages - 1] != m)) {
1012                                                 bp->b_pages[bp->b_npages] = m;
1013                                                 bp->b_npages++;
1014                                         }
1015                                 }
1016                                 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object);
1017                         }
1018                         bp->b_bcount += size;
1019                         bp->b_bufsize += size;
1020                         /*
1021                          * If any of the clustered buffers have their
1022                          * B_BARRIER flag set, transfer that request to
1023                          * the cluster.
1024                          */
1025                         bp->b_flags |= (tbp->b_flags & B_BARRIER);
1026                         tbp->b_flags &= ~(B_DONE | B_BARRIER);
1027                         tbp->b_flags |= B_ASYNC;
1028                         tbp->b_ioflags &= ~BIO_ERROR;
1029                         tbp->b_iocmd = BIO_WRITE;
1030                         bundirty(tbp);
1031                         reassignbuf(tbp);               /* put on clean list */
1032                         bufobj_wref(tbp->b_bufobj);
1033                         BUF_KERNPROC(tbp);
1034                         buf_track(tbp, __func__);
1035                         TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head,
1036                                 tbp, b_cluster.cluster_entry);
1037                 }
1038         finishcluster:
1039                 if (buf_mapped(bp)) {
1040                         pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
1041                             (vm_page_t *)bp->b_pages, bp->b_npages);
1042                 }
1043                 if (bp->b_bufsize > bp->b_kvasize)
1044                         panic(
1045                             "cluster_wbuild: b_bufsize(%ld) > b_kvasize(%d)\n",
1046                             bp->b_bufsize, bp->b_kvasize);
1047                 totalwritten += bp->b_bufsize;
1048                 bp->b_dirtyoff = 0;
1049                 bp->b_dirtyend = bp->b_bufsize;
1050                 bawrite(bp);
1051
1052                 len -= i;
1053         }
1054         return totalwritten;
1055 }
1056
1057 /*
1058  * Collect together all the buffers in a cluster.
1059  * Plus add one additional buffer.
1060  */
1061 static struct cluster_save *
1062 cluster_collectbufs(struct vnode *vp, struct buf *last_bp, int gbflags)
1063 {
1064         struct cluster_save *buflist;
1065         struct buf *bp;
1066         daddr_t lbn;
1067         int i, j, len, error;
1068
1069         len = vp->v_lastw - vp->v_cstart + 1;
1070         buflist = malloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist),
1071             M_SEGMENT, M_WAITOK);
1072         buflist->bs_nchildren = 0;
1073         buflist->bs_children = (struct buf **) (buflist + 1);
1074         for (lbn = vp->v_cstart, i = 0; i < len; lbn++, i++) {
1075                 error = bread_gb(vp, lbn, last_bp->b_bcount, NOCRED,
1076                     gbflags, &bp);
1077                 if (error != 0) {
1078                         /*
1079                          * If read fails, release collected buffers
1080                          * and return failure.
1081                          */
1082                         for (j = 0; j < i; j++)
1083                                 brelse(buflist->bs_children[j]);
1084                         free(buflist, M_SEGMENT);
1085                         return (NULL);
1086                 }
1087                 buflist->bs_children[i] = bp;
1088                 if (bp->b_blkno == bp->b_lblkno)
1089                         VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno,
1090                                 NULL, NULL);
1091         }
1092         buflist->bs_children[i] = bp = last_bp;
1093         if (bp->b_blkno == bp->b_lblkno)
1094                 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
1095         buflist->bs_nchildren = i + 1;
1096         return (buflist);
1097 }