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