sys/kern/vfs_cluster.c

   1 /*-
   2  * Copyright (c) 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  * Modifications/enhancements:
   5  *      Copyright (c) 1995 John S. Dyson.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 4. Neither the name of the University nor the names of its contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  *
  31  *      @(#)vfs_cluster.c       8.7 (Berkeley) 2/13/94
  32  */
  33
  34 #include <sys/cdefs.h>
  35 __FBSDID("$FreeBSD$");
  36
  37 #include "opt_debug_cluster.h"
  38
  39 #include <sys/param.h>
  40 #include <sys/systm.h>
  41 #include <sys/kernel.h>
  42 #include <sys/proc.h>
  43 #include <sys/bio.h>
  44 #include <sys/buf.h>
  45 #include <sys/vnode.h>
  46 #include <sys/malloc.h>
  47 #include <sys/mount.h>
  48 #include <sys/resourcevar.h>
  49 #include <sys/rwlock.h>
  50 #include <sys/vmmeter.h>
  51 #include <vm/vm.h>
  52 #include <vm/vm_object.h>
  53 #include <vm/vm_page.h>
  54 #include <sys/sysctl.h>
  55
  56 #if defined(CLUSTERDEBUG)
  57 static int      rcluster= 0;
  58 SYSCTL_INT(_debug, OID_AUTO, rcluster, CTLFLAG_RW, &rcluster, 0,
  59     "Debug VFS clustering code");
  60 #endif
  61
  62 static MALLOC_DEFINE(M_SEGMENT, "cl_savebuf", "cluster_save buffer");
  63
  64 static struct cluster_save *cluster_collectbufs(struct vnode *vp,
  65             struct buf *last_bp, int gbflags);
  66 static struct buf *cluster_rbuild(struct vnode *vp, u_quad_t filesize,
  67             daddr_t lbn, daddr_t blkno, long size, int run, int gbflags,
  68             struct buf *fbp);
  69 static void cluster_callback(struct buf *);
  70
  71 static int write_behind = 1;
  72 SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0,
  73     "Cluster write-behind; 0: disable, 1: enable, 2: backed off");
  74
  75 static int read_max = 64;
  76 SYSCTL_INT(_vfs, OID_AUTO, read_max, CTLFLAG_RW, &read_max, 0,
  77     "Cluster read-ahead max block count");
  78
  79 static int read_min = 1;
  80 SYSCTL_INT(_vfs, OID_AUTO, read_min, CTLFLAG_RW, &read_min, 0,
  81     "Cluster read min block count");
  82
  83 /* Page expended to mark partially backed buffers */
  84 extern vm_page_t        bogus_page;
  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                 curthread->td_ru.ru_inblock++;
 245         }
 246
 247         /*
 248          * If we have been doing sequential I/O, then do some read-ahead.
 249          */
 250         while (lblkno < (origblkno + maxra)) {
 251                 error = VOP_BMAP(vp, lblkno, NULL, &blkno, &ncontig, NULL);
 252                 if (error)
 253                         break;
 254
 255                 if (blkno == -1)
 256                         break;
 257
 258                 /*
 259                  * We could throttle ncontig here by maxra but we might as
 260                  * well read the data if it is contiguous.  We're throttled
 261                  * by racluster anyway.
 262                  */
 263                 if (ncontig) {
 264                         ncontig = min(ncontig + 1, racluster);
 265                         rbp = cluster_rbuild(vp, filesize, lblkno, blkno,
 266                             size, ncontig, gbflags, NULL);
 267                         lblkno += (rbp->b_bufsize / size);
 268                         if (rbp->b_flags & B_DELWRI) {
 269                                 bqrelse(rbp);
 270                                 continue;
 271                         }
 272                 } else {
 273                         rbp = getblk(vp, lblkno, size, 0, 0, gbflags);
 274                         lblkno += 1;
 275                         if (rbp->b_flags & B_DELWRI) {
 276                                 bqrelse(rbp);
 277                                 continue;
 278                         }
 279                         rbp->b_flags |= B_ASYNC | B_RAM;
 280                         rbp->b_iocmd = BIO_READ;
 281                         rbp->b_blkno = blkno;
 282                 }
 283                 if (rbp->b_flags & B_CACHE) {
 284                         rbp->b_flags &= ~B_ASYNC;
 285                         bqrelse(rbp);
 286                         continue;
 287                 }
 288                 if ((rbp->b_flags & B_CLUSTER) == 0) {
 289                         vfs_busy_pages(rbp, 0);
 290                 }
 291                 rbp->b_flags &= ~B_INVAL;
 292                 rbp->b_ioflags &= ~BIO_ERROR;
 293                 if ((rbp->b_flags & B_ASYNC) || rbp->b_iodone != NULL)
 294                         BUF_KERNPROC(rbp);
 295                 rbp->b_iooffset = dbtob(rbp->b_blkno);
 296                 bstrategy(rbp);
 297                 curthread->td_ru.ru_inblock++;
 298         }
 299
 300         if (reqbp) {
 301                 /*
 302                  * Like bread, always brelse() the buffer when
 303                  * returning an error.
 304                  */
 305                 error = bufwait(reqbp);
 306                 if (error != 0) {
 307                         brelse(reqbp);
 308                         *bpp = NULL;
 309                 }
 310         }
 311         return (error);
 312 }
 313
 314 /*
 315  * If blocks are contiguous on disk, use this to provide clustered
 316  * read ahead.  We will read as many blocks as possible sequentially
 317  * and then parcel them up into logical blocks in the buffer hash table.
 318  */
 319 static struct buf *
 320 cluster_rbuild(struct vnode *vp, u_quad_t filesize, daddr_t lbn,
 321     daddr_t blkno, long size, int run, int gbflags, struct buf *fbp)
 322 {
 323         struct buf *bp, *tbp;
 324         daddr_t bn;
 325         off_t off;
 326         long tinc, tsize;
 327         int i, inc, j, k, toff;
 328
 329         KASSERT(size == vp->v_mount->mnt_stat.f_iosize,
 330             ("cluster_rbuild: size %ld != f_iosize %jd\n",
 331             size, (intmax_t)vp->v_mount->mnt_stat.f_iosize));
 332
 333         /*
 334          * avoid a division
 335          */
 336         while ((u_quad_t) size * (lbn + run) > filesize) {
 337                 --run;
 338         }
 339
 340         if (fbp) {
 341                 tbp = fbp;
 342                 tbp->b_iocmd = BIO_READ;
 343         } else {
 344                 tbp = getblk(vp, lbn, size, 0, 0, gbflags);
 345                 if (tbp->b_flags & B_CACHE)
 346                         return tbp;
 347                 tbp->b_flags |= B_ASYNC | B_RAM;
 348                 tbp->b_iocmd = BIO_READ;
 349         }
 350         tbp->b_blkno = blkno;
 351         if( (tbp->b_flags & B_MALLOC) ||
 352                 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1) )
 353                 return tbp;
 354
 355         bp = trypbuf(&cluster_pbuf_freecnt);
 356         if (bp == 0)
 357                 return tbp;
 358
 359         /*
 360          * We are synthesizing a buffer out of vm_page_t's, but
 361          * if the block size is not page aligned then the starting
 362          * address may not be either.  Inherit the b_data offset
 363          * from the original buffer.
 364          */
 365         bp->b_flags = B_ASYNC | B_CLUSTER | B_VMIO;
 366         if ((gbflags & GB_UNMAPPED) != 0) {
 367                 bp->b_data = unmapped_buf;
 368         } else {
 369                 bp->b_data = (char *)((vm_offset_t)bp->b_data |
 370                     ((vm_offset_t)tbp->b_data & PAGE_MASK));
 371         }
 372         bp->b_iocmd = BIO_READ;
 373         bp->b_iodone = cluster_callback;
 374         bp->b_blkno = blkno;
 375         bp->b_lblkno = lbn;
 376         bp->b_offset = tbp->b_offset;
 377         KASSERT(bp->b_offset != NOOFFSET, ("cluster_rbuild: no buffer offset"));
 378         pbgetvp(vp, bp);
 379
 380         TAILQ_INIT(&bp->b_cluster.cluster_head);
 381
 382         bp->b_bcount = 0;
 383         bp->b_bufsize = 0;
 384         bp->b_npages = 0;
 385
 386         inc = btodb(size);
 387         for (bn = blkno, i = 0; i < run; ++i, bn += inc) {
 388                 if (i == 0) {
 389                         VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object);
 390                         vfs_drain_busy_pages(tbp);
 391                         vm_object_pip_add(tbp->b_bufobj->bo_object,
 392                             tbp->b_npages);
 393                         for (k = 0; k < tbp->b_npages; k++)
 394                                 vm_page_sbusy(tbp->b_pages[k]);
 395                         VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object);
 396                 } else {
 397                         if ((bp->b_npages * PAGE_SIZE) +
 398                             round_page(size) > vp->v_mount->mnt_iosize_max) {
 399                                 break;
 400                         }
 401
 402                         tbp = getblk(vp, lbn + i, size, 0, 0, GB_LOCK_NOWAIT |
 403                             (gbflags & GB_UNMAPPED));
 404
 405                         /* Don't wait around for locked bufs. */
 406                         if (tbp == NULL)
 407                                 break;
 408
 409                         /*
 410                          * Stop scanning if the buffer is fully valid
 411                          * (marked B_CACHE), or locked (may be doing a
 412                          * background write), or if the buffer is not
 413                          * VMIO backed.  The clustering code can only deal
 414                          * with VMIO-backed buffers.  The bo lock is not
 415                          * required for the BKGRDINPROG check since it
 416                          * can not be set without the buf lock.
 417                          */
 418                         if ((tbp->b_vflags & BV_BKGRDINPROG) ||
 419                             (tbp->b_flags & B_CACHE) ||
 420                             (tbp->b_flags & B_VMIO) == 0) {
 421                                 bqrelse(tbp);
 422                                 break;
 423                         }
 424
 425                         /*
 426                          * The buffer must be completely invalid in order to
 427                          * take part in the cluster.  If it is partially valid
 428                          * then we stop.
 429                          */
 430                         off = tbp->b_offset;
 431                         tsize = size;
 432                         VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object);
 433                         for (j = 0; tsize > 0; j++) {
 434                                 toff = off & PAGE_MASK;
 435                                 tinc = tsize;
 436                                 if (toff + tinc > PAGE_SIZE)
 437                                         tinc = PAGE_SIZE - toff;
 438                                 VM_OBJECT_ASSERT_WLOCKED(tbp->b_pages[j]->object);
 439                                 if ((tbp->b_pages[j]->valid &
 440                                     vm_page_bits(toff, tinc)) != 0)
 441                                         break;
 442                                 if (vm_page_xbusied(tbp->b_pages[j]))
 443                                         break;
 444                                 vm_object_pip_add(tbp->b_bufobj->bo_object, 1);
 445                                 vm_page_sbusy(tbp->b_pages[j]);
 446                                 off += tinc;
 447                                 tsize -= tinc;
 448                         }
 449                         if (tsize > 0) {
 450 clean_sbusy:
 451                                 vm_object_pip_add(tbp->b_bufobj->bo_object, -j);
 452                                 for (k = 0; k < j; k++)
 453                                         vm_page_sunbusy(tbp->b_pages[k]);
 454                                 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object);
 455                                 bqrelse(tbp);
 456                                 break;
 457                         }
 458                         VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object);
 459
 460                         /*
 461                          * Set a read-ahead mark as appropriate
 462                          */
 463                         if ((fbp && (i == 1)) || (i == (run - 1)))
 464                                 tbp->b_flags |= B_RAM;
 465
 466                         /*
 467                          * Set the buffer up for an async read (XXX should
 468                          * we do this only if we do not wind up brelse()ing?).
 469                          * Set the block number if it isn't set, otherwise
 470                          * if it is make sure it matches the block number we
 471                          * expect.
 472                          */
 473                         tbp->b_flags |= B_ASYNC;
 474                         tbp->b_iocmd = BIO_READ;
 475                         if (tbp->b_blkno == tbp->b_lblkno) {
 476                                 tbp->b_blkno = bn;
 477                         } else if (tbp->b_blkno != bn) {
 478                                 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object);
 479                                 goto clean_sbusy;
 480                         }
 481                 }
 482                 /*
 483                  * XXX fbp from caller may not be B_ASYNC, but we are going
 484                  * to biodone() it in cluster_callback() anyway
 485                  */
 486                 BUF_KERNPROC(tbp);
 487                 TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head,
 488                         tbp, b_cluster.cluster_entry);
 489                 VM_OBJECT_WLOCK(tbp->b_bufobj->bo_object);
 490                 for (j = 0; j < tbp->b_npages; j += 1) {
 491                         vm_page_t m;
 492                         m = tbp->b_pages[j];
 493                         if ((bp->b_npages == 0) ||
 494                             (bp->b_pages[bp->b_npages-1] != m)) {
 495                                 bp->b_pages[bp->b_npages] = m;
 496                                 bp->b_npages++;
 497                         }
 498                         if (m->valid == VM_PAGE_BITS_ALL)
 499                                 tbp->b_pages[j] = bogus_page;
 500                 }
 501                 VM_OBJECT_WUNLOCK(tbp->b_bufobj->bo_object);
 502                 /*
 503                  * Don't inherit tbp->b_bufsize as it may be larger due to
 504                  * a non-page-aligned size.  Instead just aggregate using
 505                  * 'size'.
 506                  */
 507                 if (tbp->b_bcount != size)
 508                         printf("warning: tbp->b_bcount wrong %ld vs %ld\n", tbp->b_bcount, size);
 509                 if (tbp->b_bufsize != size)
 510                         printf("warning: tbp->b_bufsize wrong %ld vs %ld\n", tbp->b_bufsize, size);
 511                 bp->b_bcount += size;
 512                 bp->b_bufsize += size;
 513         }
 514
 515         /*
 516          * Fully valid pages in the cluster are already good and do not need
 517          * to be re-read from disk.  Replace the page with bogus_page
 518          */
 519         VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
 520         for (j = 0; j < bp->b_npages; j++) {
 521                 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[j]->object);
 522                 if (bp->b_pages[j]->valid == VM_PAGE_BITS_ALL)
 523                         bp->b_pages[j] = bogus_page;
 524         }
 525         VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
 526         if (bp->b_bufsize > bp->b_kvasize)
 527                 panic("cluster_rbuild: b_bufsize(%ld) > b_kvasize(%d)\n",
 528                     bp->b_bufsize, bp->b_kvasize);
 529
 530         if (buf_mapped(bp)) {
 531                 pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
 532                     (vm_page_t *)bp->b_pages, bp->b_npages);
 533         }
 534         return (bp);
 535 }
 536
 537 /*
 538  * Cleanup after a clustered read or write.
 539  * This is complicated by the fact that any of the buffers might have
 540  * extra memory (if there were no empty buffer headers at allocbuf time)
 541  * that we will need to shift around.
 542  */
 543 static void
 544 cluster_callback(bp)
 545         struct buf *bp;
 546 {
 547         struct buf *nbp, *tbp;
 548         int error = 0;
 549
 550         /*
 551          * Must propogate errors to all the components.
 552          */
 553         if (bp->b_ioflags & BIO_ERROR)
 554                 error = bp->b_error;
 555
 556         if (buf_mapped(bp)) {
 557                 pmap_qremove(trunc_page((vm_offset_t) bp->b_data),
 558                     bp->b_npages);
 559         }
 560         /*
 561          * Move memory from the large cluster buffer into the component
 562          * buffers and mark IO as done on these.
 563          */
 564         for (tbp = TAILQ_FIRST(&bp->b_cluster.cluster_head);
 565                 tbp; tbp = nbp) {
 566                 nbp = TAILQ_NEXT(&tbp->b_cluster, cluster_entry);
 567                 if (error) {
 568                         tbp->b_ioflags |= BIO_ERROR;
 569                         tbp->b_error = error;
 570                 } else {
 571                         tbp->b_dirtyoff = tbp->b_dirtyend = 0;
 572                         tbp->b_flags &= ~B_INVAL;
 573                         tbp->b_ioflags &= ~BIO_ERROR;
 574                         /*
 575                          * XXX the bdwrite()/bqrelse() issued during
 576                          * cluster building clears B_RELBUF (see bqrelse()
 577                          * comment).  If direct I/O was specified, we have
 578                          * to restore it here to allow the buffer and VM
 579                          * to be freed.
 580                          */
 581                         if (tbp->b_flags & B_DIRECT)
 582                                 tbp->b_flags |= B_RELBUF;
 583                 }
 584                 bufdone(tbp);
 585         }
 586         pbrelvp(bp);
 587         relpbuf(bp, &cluster_pbuf_freecnt);
 588 }
 589
 590 /*
 591  *      cluster_wbuild_wb:
 592  *
 593  *      Implement modified write build for cluster.
 594  *
 595  *              write_behind = 0        write behind disabled
 596  *              write_behind = 1        write behind normal (default)
 597  *              write_behind = 2        write behind backed-off
 598  */
 599
 600 static __inline int
 601 cluster_wbuild_wb(struct vnode *vp, long size, daddr_t start_lbn, int len,
 602     int gbflags)
 603 {
 604         int r = 0;
 605
 606         switch (write_behind) {
 607         case 2:
 608                 if (start_lbn < len)
 609                         break;
 610                 start_lbn -= len;
 611                 /* FALLTHROUGH */
 612         case 1:
 613                 r = cluster_wbuild(vp, size, start_lbn, len, gbflags);
 614                 /* FALLTHROUGH */
 615         default:
 616                 /* FALLTHROUGH */
 617                 break;
 618         }
 619         return(r);
 620 }
 621
 622 /*
 623  * Do clustered write for FFS.
 624  *
 625  * Three cases:
 626  *      1. Write is not sequential (write asynchronously)
 627  *      Write is sequential:
 628  *      2.      beginning of cluster - begin cluster
 629  *      3.      middle of a cluster - add to cluster
 630  *      4.      end of a cluster - asynchronously write cluster
 631  */
 632 void
 633 cluster_write(struct vnode *vp, struct buf *bp, u_quad_t filesize, int seqcount,
 634     int gbflags)
 635 {
 636         daddr_t lbn;
 637         int maxclen, cursize;
 638         int lblocksize;
 639         int async;
 640
 641         if (!unmapped_buf_allowed)
 642                 gbflags &= ~GB_UNMAPPED;
 643
 644         if (vp->v_type == VREG) {
 645                 async = DOINGASYNC(vp);
 646                 lblocksize = vp->v_mount->mnt_stat.f_iosize;
 647         } else {
 648                 async = 0;
 649                 lblocksize = bp->b_bufsize;
 650         }
 651         lbn = bp->b_lblkno;
 652         KASSERT(bp->b_offset != NOOFFSET, ("cluster_write: no buffer offset"));
 653
 654         /* Initialize vnode to beginning of file. */
 655         if (lbn == 0)
 656                 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0;
 657
 658         if (vp->v_clen == 0 || lbn != vp->v_lastw + 1 ||
 659             (bp->b_blkno != vp->v_lasta + btodb(lblocksize))) {
 660                 maxclen = vp->v_mount->mnt_iosize_max / lblocksize - 1;
 661                 if (vp->v_clen != 0) {
 662                         /*
 663                          * Next block is not sequential.
 664                          *
 665                          * If we are not writing at end of file, the process
 666                          * seeked to another point in the file since its last
 667                          * write, or we have reached our maximum cluster size,
 668                          * then push the previous cluster. Otherwise try
 669                          * reallocating to make it sequential.
 670                          *
 671                          * Change to algorithm: only push previous cluster if
 672                          * it was sequential from the point of view of the
 673                          * seqcount heuristic, otherwise leave the buffer
 674                          * intact so we can potentially optimize the I/O
 675                          * later on in the buf_daemon or update daemon
 676                          * flush.
 677                          */
 678                         cursize = vp->v_lastw - vp->v_cstart + 1;
 679                         if (((u_quad_t) bp->b_offset + lblocksize) != filesize ||
 680                             lbn != vp->v_lastw + 1 || vp->v_clen <= cursize) {
 681                                 if (!async && seqcount > 0) {
 682                                         cluster_wbuild_wb(vp, lblocksize,
 683                                             vp->v_cstart, cursize, gbflags);
 684                                 }
 685                         } else {
 686                                 struct buf **bpp, **endbp;
 687                                 struct cluster_save *buflist;
 688
 689                                 buflist = cluster_collectbufs(vp, bp, gbflags);
 690                                 endbp = &buflist->bs_children
 691                                     [buflist->bs_nchildren - 1];
 692                                 if (VOP_REALLOCBLKS(vp, buflist)) {
 693                                         /*
 694                                          * Failed, push the previous cluster
 695                                          * if *really* writing sequentially
 696                                          * in the logical file (seqcount > 1),
 697                                          * otherwise delay it in the hopes that
 698                                          * the low level disk driver can
 699                                          * optimize the write ordering.
 700                                          */
 701                                         for (bpp = buflist->bs_children;
 702                                              bpp < endbp; bpp++)
 703                                                 brelse(*bpp);
 704                                         free(buflist, M_SEGMENT);
 705                                         if (seqcount > 1) {
 706                                                 cluster_wbuild_wb(vp,
 707                                                     lblocksize, vp->v_cstart,
 708                                                     cursize, gbflags);
 709                                         }
 710                                 } else {
 711                                         /*
 712                                          * Succeeded, keep building cluster.
 713                                          */
 714                                         for (bpp = buflist->bs_children;
 715                                              bpp <= endbp; bpp++)
 716                                                 bdwrite(*bpp);
 717                                         free(buflist, M_SEGMENT);
 718                                         vp->v_lastw = lbn;
 719                                         vp->v_lasta = bp->b_blkno;
 720                                         return;
 721                                 }
 722                         }
 723                 }
 724                 /*
 725                  * Consider beginning a cluster. If at end of file, make
 726                  * cluster as large as possible, otherwise find size of
 727                  * existing cluster.
 728                  */
 729                 if ((vp->v_type == VREG) &&
 730                         ((u_quad_t) bp->b_offset + lblocksize) != filesize &&
 731                     (bp->b_blkno == bp->b_lblkno) &&
 732                     (VOP_BMAP(vp, lbn, NULL, &bp->b_blkno, &maxclen, NULL) ||
 733                      bp->b_blkno == -1)) {
 734                         bawrite(bp);
 735                         vp->v_clen = 0;
 736                         vp->v_lasta = bp->b_blkno;
 737                         vp->v_cstart = lbn + 1;
 738                         vp->v_lastw = lbn;
 739                         return;
 740                 }
 741                 vp->v_clen = maxclen;
 742                 if (!async && maxclen == 0) {   /* I/O not contiguous */
 743                         vp->v_cstart = lbn + 1;
 744                         bawrite(bp);
 745                 } else {        /* Wait for rest of cluster */
 746                         vp->v_cstart = lbn;
 747                         bdwrite(bp);
 748                 }
 749         } else if (lbn == vp->v_cstart + vp->v_clen) {
 750                 /*
 751                  * At end of cluster, write it out if seqcount tells us we
 752                  * are operating sequentially, otherwise let the buf or
 753                  * update daemon handle it.
 754                  */
 755                 bdwrite(bp);
 756                 if (seqcount > 1) {
 757                         cluster_wbuild_wb(vp, lblocksize, vp->v_cstart,
 758                             vp->v_clen + 1, gbflags);
 759                 }
 760                 vp->v_clen = 0;
 761                 vp->v_cstart = lbn + 1;
 762         } else if (vm_page_count_severe()) {
 763                 /*
 764                  * We are low on memory, get it going NOW
 765                  */
 766                 bawrite(bp);
 767         } else {
 768                 /*
 769                  * In the middle of a cluster, so just delay the I/O for now.
 770                  */
 771                 bdwrite(bp);
 772         }
 773         vp->v_lastw = lbn;
 774         vp->v_lasta = bp->b_blkno;
 775 }
 776
 777
 778 /*
 779  * This is an awful lot like cluster_rbuild...wish they could be combined.
 780  * The last lbn argument is the current block on which I/O is being
 781  * performed.  Check to see that it doesn't fall in the middle of
 782  * the current block (if last_bp == NULL).
 783  */
 784 int
 785 cluster_wbuild(struct vnode *vp, long size, daddr_t start_lbn, int len,
 786     int gbflags)
 787 {
 788         struct buf *bp, *tbp;
 789         struct bufobj *bo;
 790         int i, j;
 791         int totalwritten = 0;
 792         int dbsize = btodb(size);
 793
 794         if (!unmapped_buf_allowed)
 795                 gbflags &= ~GB_UNMAPPED;
 796
 797         bo = &vp->v_bufobj;
 798         while (len > 0) {
 799                 /*
 800                  * If the buffer is not delayed-write (i.e. dirty), or it
 801                  * is delayed-write but either locked or inval, it cannot
 802                  * partake in the clustered write.
 803                  */
 804                 BO_LOCK(bo);
 805                 if ((tbp = gbincore(&vp->v_bufobj, start_lbn)) == NULL ||
 806                     (tbp->b_vflags & BV_BKGRDINPROG)) {
 807                         BO_UNLOCK(bo);
 808                         ++start_lbn;
 809                         --len;
 810                         continue;
 811                 }
 812                 if (BUF_LOCK(tbp,
 813                     LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, BO_LOCKPTR(bo))) {
 814                         ++start_lbn;
 815                         --len;
 816                         continue;
 817                 }
 818                 if ((tbp->b_flags & (B_INVAL | B_DELWRI)) != B_DELWRI) {
 819                         BUF_UNLOCK(tbp);
 820                         ++start_lbn;
 821                         --len;
 822                         continue;
 823                 }
 824                 if (tbp->b_pin_count >  0) {
 825                         BUF_UNLOCK(tbp);
 826                         ++start_lbn;
 827                         --len;
 828                         continue;
 829                 }
 830                 bremfree(tbp);
 831                 tbp->b_flags &= ~B_DONE;
 832
 833                 /*
 834                  * Extra memory in the buffer, punt on this buffer.
 835                  * XXX we could handle this in most cases, but we would
 836                  * have to push the extra memory down to after our max
 837                  * possible cluster size and then potentially pull it back
 838                  * up if the cluster was terminated prematurely--too much
 839                  * hassle.
 840                  */
 841                 if (((tbp->b_flags & (B_CLUSTEROK | B_MALLOC | B_VMIO)) !=
 842                      (B_CLUSTEROK | B_VMIO)) ||
 843                   (tbp->b_bcount != tbp->b_bufsize) ||
 844                   (tbp->b_bcount != size) ||
 845                   (len == 1) ||
 846                   ((bp = (vp->v_vflag & VV_MD) != 0 ?
 847                   trypbuf(&cluster_pbuf_freecnt) :
 848                   getpbuf(&cluster_pbuf_freecnt)) == NULL)) {
 849                         totalwritten += tbp->b_bufsize;
 850                         bawrite(tbp);
 851                         ++start_lbn;
 852                         --len;
 853                         continue;
 854                 }
 855
 856                 /*
 857                  * We got a pbuf to make the cluster in.
 858                  * so initialise it.
 859                  */
 860                 TAILQ_INIT(&bp->b_cluster.cluster_head);
 861                 bp->b_bcount = 0;
 862                 bp->b_bufsize = 0;
 863                 bp->b_npages = 0;
 864                 if (tbp->b_wcred != NOCRED)
 865                         bp->b_wcred = crhold(tbp->b_wcred);
 866
 867                 bp->b_blkno = tbp->b_blkno;
 868                 bp->b_lblkno = tbp->b_lblkno;
 869                 bp->b_offset = tbp->b_offset;
 870
 871                 /*
 872                  * We are synthesizing a buffer out of vm_page_t's, but
 873                  * if the block size is not page aligned then the starting
 874                  * address may not be either.  Inherit the b_data offset
 875                  * from the original buffer.
 876                  */
 877                 if ((gbflags & GB_UNMAPPED) == 0 ||
 878                     (tbp->b_flags & B_VMIO) == 0) {
 879                         bp->b_data = (char *)((vm_offset_t)bp->b_data |
 880                             ((vm_offset_t)tbp->b_data & PAGE_MASK));
 881                 } else {
 882                         bp->b_data = unmapped_buf;
 883                 }
 884                 bp->b_flags |= B_CLUSTER | (tbp->b_flags & (B_VMIO |
 885                     B_NEEDCOMMIT));
 886                 bp->b_iodone = cluster_callback;
 887                 pbgetvp(vp, bp);
 888                 /*
 889                  * From this location in the file, scan forward to see
 890                  * if there are buffers with adjacent data that need to
 891                  * be written as well.
 892                  */
 893                 for (i = 0; i < len; ++i, ++start_lbn) {
 894                         if (i != 0) { /* If not the first buffer */
 895                                 /*
 896                                  * If the adjacent data is not even in core it
 897                                  * can't need to be written.
 898                                  */
 899                                 BO_LOCK(bo);
 900                                 if ((tbp = gbincore(bo, start_lbn)) == NULL ||
 901                                     (tbp->b_vflags & BV_BKGRDINPROG)) {
 902                                         BO_UNLOCK(bo);
 903                                         break;
 904                                 }
 905
 906                                 /*
 907                                  * If it IS in core, but has different
 908                                  * characteristics, or is locked (which
 909                                  * means it could be undergoing a background
 910                                  * I/O or be in a weird state), then don't
 911                                  * cluster with it.
 912                                  */
 913                                 if (BUF_LOCK(tbp,
 914                                     LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK,
 915                                     BO_LOCKPTR(bo)))
 916                                         break;
 917
 918                                 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK |
 919                                     B_INVAL | B_DELWRI | B_NEEDCOMMIT))
 920                                     != (B_DELWRI | B_CLUSTEROK |
 921                                     (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) ||
 922                                     tbp->b_wcred != bp->b_wcred) {
 923                                         BUF_UNLOCK(tbp);
 924                                         break;
 925                                 }
 926
 927                                 /*
 928                                  * Check that the combined cluster
 929                                  * would make sense with regard to pages
 930                                  * and would not be too large
 931                                  */
 932                                 if ((tbp->b_bcount != size) ||
 933                                   ((bp->b_blkno + (dbsize * i)) !=
 934                                     tbp->b_blkno) ||
 935                                   ((tbp->b_npages + bp->b_npages) >
 936                                     (vp->v_mount->mnt_iosize_max / PAGE_SIZE))) {
 937                                         BUF_UNLOCK(tbp);
 938                                         break;
 939                                 }
 940
 941                                 /*
 942                                  * Do not pull in pinned buffers.
 943                                  */
 944                                 if (tbp->b_pin_count > 0) {
 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                         TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head,
1011                                 tbp, b_cluster.cluster_entry);
1012                 }
1013         finishcluster:
1014                 if (buf_mapped(bp)) {
1015                         pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
1016                             (vm_page_t *)bp->b_pages, bp->b_npages);
1017                 }
1018                 if (bp->b_bufsize > bp->b_kvasize)
1019                         panic(
1020                             "cluster_wbuild: b_bufsize(%ld) > b_kvasize(%d)\n",
1021                             bp->b_bufsize, bp->b_kvasize);
1022                 totalwritten += bp->b_bufsize;
1023                 bp->b_dirtyoff = 0;
1024                 bp->b_dirtyend = bp->b_bufsize;
1025                 bawrite(bp);
1026
1027                 len -= i;
1028         }
1029         return totalwritten;
1030 }
1031
1032 /*
1033  * Collect together all the buffers in a cluster.
1034  * Plus add one additional buffer.
1035  */
1036 static struct cluster_save *
1037 cluster_collectbufs(struct vnode *vp, struct buf *last_bp, int gbflags)
1038 {
1039         struct cluster_save *buflist;
1040         struct buf *bp;
1041         daddr_t lbn;
1042         int i, len;
1043
1044         len = vp->v_lastw - vp->v_cstart + 1;
1045         buflist = malloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist),
1046             M_SEGMENT, M_WAITOK);
1047         buflist->bs_nchildren = 0;
1048         buflist->bs_children = (struct buf **) (buflist + 1);
1049         for (lbn = vp->v_cstart, i = 0; i < len; lbn++, i++) {
1050                 (void)bread_gb(vp, lbn, last_bp->b_bcount, NOCRED,
1051                     gbflags, &bp);
1052                 buflist->bs_children[i] = bp;
1053                 if (bp->b_blkno == bp->b_lblkno)
1054                         VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno,
1055                                 NULL, NULL);
1056         }
1057         buflist->bs_children[i] = bp = last_bp;
1058         if (bp->b_blkno == bp->b_lblkno)
1059                 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
1060         buflist->bs_nchildren = i + 1;
1061         return (buflist);
1062 }