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