sys/kern/vfs_cluster.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-3-Clause
   3  *
   4  * Copyright (c) 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  * Modifications/enhancements:
   7  *      Copyright (c) 1995 John S. Dyson.  All rights reserved.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions
  11  * are met:
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in the
  16  *    documentation and/or other materials provided with the distribution.
  17  * 3. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  *
  33  *      @(#)vfs_cluster.c       8.7 (Berkeley) 2/13/94
  34  */
  35
  36 #include <sys/cdefs.h>
  37 #include <sys/param.h>
  38 #include <sys/systm.h>
  39 #include <sys/kernel.h>
  40 #include <sys/proc.h>
  41 #include <sys/bio.h>
  42 #include <sys/buf.h>
  43 #include <sys/vnode.h>
  44 #include <sys/malloc.h>
  45 #include <sys/mount.h>
  46 #include <sys/racct.h>
  47 #include <sys/resourcevar.h>
  48 #include <sys/rwlock.h>
  49 #include <sys/vmmeter.h>
  50 #include <vm/vm.h>
  51 #include <vm/vm_object.h>
  52 #include <vm/vm_page.h>
  53 #include <sys/sysctl.h>
  54
  55 static MALLOC_DEFINE(M_SEGMENT, "cl_savebuf", "cluster_save buffer");
  56 static uma_zone_t cluster_pbuf_zone;
  57
  58 static void cluster_init(void *);
  59 static struct cluster_save *cluster_collectbufs(struct vnode *vp,
  60             struct buf *last_bp, int gbflags);
  61 static struct buf *cluster_rbuild(struct vnode *vp, u_quad_t filesize,
  62             daddr_t lbn, daddr_t blkno, long size, int run, int gbflags,
  63             struct buf *fbp);
  64 static void cluster_callback(struct buf *);
  65
  66 static int write_behind = 1;
  67 SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0,
  68     "Cluster write-behind; 0: disable, 1: enable, 2: backed off");
  69
  70 static int read_max = 64;
  71 SYSCTL_INT(_vfs, OID_AUTO, read_max, CTLFLAG_RW, &read_max, 0,
  72     "Cluster read-ahead max block count");
  73
  74 static int read_min = 1;
  75 SYSCTL_INT(_vfs, OID_AUTO, read_min, CTLFLAG_RW, &read_min, 0,
  76     "Cluster read min block count");
  77
  78 SYSINIT(cluster, SI_SUB_CPU, SI_ORDER_ANY, cluster_init, NULL);
  79
  80 static void
  81 cluster_init(void *dummy)
  82 {
  83
  84         cluster_pbuf_zone = pbuf_zsecond_create("clpbuf", nswbuf / 2);
  85 }
  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         struct thread *td;
  99         daddr_t blkno, origblkno;
 100         int maxra, racluster;
 101         int error, ncontig;
 102         int i;
 103
 104         error = 0;
 105         td = curthread;
 106         bo = &vp->v_bufobj;
 107         if (!unmapped_buf_allowed)
 108                 gbflags &= ~GB_UNMAPPED;
 109
 110         /*
 111          * Try to limit the amount of read-ahead by a few
 112          * ad-hoc parameters.  This needs work!!!
 113          */
 114         racluster = vp->v_mount->mnt_iosize_max / size;
 115         maxra = seqcount;
 116         maxra = min(read_max, maxra);
 117         maxra = min(nbuf/8, maxra);
 118         if (((u_quad_t)(lblkno + maxra + 1) * size) > filesize)
 119                 maxra = (filesize / size) - lblkno;
 120
 121         /*
 122          * get the requested block
 123          */
 124         error = getblkx(vp, lblkno, lblkno, size, 0, 0, gbflags, &bp);
 125         if (error != 0) {
 126                 *bpp = NULL;
 127                 return (error);
 128         }
 129         gbflags &= ~GB_NOSPARSE;
 130         origblkno = lblkno;
 131         *bpp = reqbp = bp;
 132
 133         /*
 134          * if it is in the cache, then check to see if the reads have been
 135          * sequential.  If they have, then try some read-ahead, otherwise
 136          * back-off on prospective read-aheads.
 137          */
 138         if (bp->b_flags & B_CACHE) {
 139                 if (!seqcount) {
 140                         return 0;
 141                 } else if ((bp->b_flags & B_RAM) == 0) {
 142                         return 0;
 143                 } else {
 144                         bp->b_flags &= ~B_RAM;
 145                         BO_RLOCK(bo);
 146                         for (i = 1; i < maxra; i++) {
 147                                 /*
 148                                  * Stop if the buffer does not exist or it
 149                                  * is invalid (about to go away?)
 150                                  */
 151                                 rbp = gbincore(&vp->v_bufobj, lblkno+i);
 152                                 if (rbp == NULL || (rbp->b_flags & B_INVAL))
 153                                         break;
 154
 155                                 /*
 156                                  * Set another read-ahead mark so we know
 157                                  * to check again. (If we can lock the
 158                                  * buffer without waiting)
 159                                  */
 160                                 if ((((i % racluster) == (racluster - 1)) ||
 161                                     (i == (maxra - 1)))
 162                                     && (0 == BUF_LOCK(rbp,
 163                                         LK_EXCLUSIVE | LK_NOWAIT, NULL))) {
 164                                         rbp->b_flags |= B_RAM;
 165                                         BUF_UNLOCK(rbp);
 166                                 }
 167                         }
 168                         BO_RUNLOCK(bo);
 169                         if (i >= maxra) {
 170                                 return 0;
 171                         }
 172                         lblkno += i;
 173                 }
 174                 reqbp = bp = NULL;
 175         /*
 176          * If it isn't in the cache, then get a chunk from
 177          * disk if sequential, otherwise just get the block.
 178          */
 179         } else {
 180                 off_t firstread = bp->b_offset;
 181                 int nblks;
 182                 long minread;
 183
 184                 KASSERT(bp->b_offset != NOOFFSET,
 185                     ("cluster_read: no buffer offset"));
 186
 187                 ncontig = 0;
 188
 189                 /*
 190                  * Adjust totread if needed
 191                  */
 192                 minread = read_min * size;
 193                 if (minread > totread)
 194                         totread = minread;
 195
 196                 /*
 197                  * Compute the total number of blocks that we should read
 198                  * synchronously.
 199                  */
 200                 if (firstread + totread > filesize)
 201                         totread = filesize - firstread;
 202                 nblks = howmany(totread, size);
 203                 if (nblks > racluster)
 204                         nblks = racluster;
 205
 206                 /*
 207                  * Now compute the number of contiguous blocks.
 208                  */
 209                 if (nblks > 1) {
 210                         error = VOP_BMAP(vp, lblkno, NULL,
 211                                 &blkno, &ncontig, NULL);
 212                         /*
 213                          * If this failed to map just do the original block.
 214                          */
 215                         if (error || blkno == -1)
 216                                 ncontig = 0;
 217                 }
 218
 219                 /*
 220                  * If we have contiguous data available do a cluster
 221                  * otherwise just read the requested block.
 222                  */
 223                 if (ncontig) {
 224                         /* Account for our first block. */
 225                         ncontig = min(ncontig + 1, nblks);
 226                         if (ncontig < nblks)
 227                                 nblks = ncontig;
 228                         bp = cluster_rbuild(vp, filesize, lblkno,
 229                             blkno, size, nblks, gbflags, bp);
 230                         lblkno += (bp->b_bufsize / size);
 231                 } else {
 232                         bp->b_flags |= B_RAM;
 233                         bp->b_iocmd = BIO_READ;
 234                         lblkno += 1;
 235                 }
 236         }
 237
 238         /*
 239          * handle the synchronous read so that it is available ASAP.
 240          */
 241         if (bp) {
 242                 if ((bp->b_flags & B_CLUSTER) == 0) {
 243                         vfs_busy_pages(bp, 0);
 244                 }
 245                 bp->b_flags &= ~B_INVAL;
 246                 bp->b_ioflags &= ~BIO_ERROR;
 247                 if ((bp->b_flags & B_ASYNC) || bp->b_iodone != NULL)
 248                         BUF_KERNPROC(bp);
 249                 bp->b_iooffset = dbtob(bp->b_blkno);
 250                 bstrategy(bp);
 251 #ifdef RACCT
 252                 if (racct_enable) {
 253                         PROC_LOCK(td->td_proc);
 254                         racct_add_buf(td->td_proc, bp, 0);
 255                         PROC_UNLOCK(td->td_proc);
 256                 }
 257 #endif /* RACCT */
 258                 td->td_ru.ru_inblock++;
 259         }
 260
 261         /*
 262          * If we have been doing sequential I/O, then do some read-ahead.
 263          */
 264         while (lblkno < (origblkno + maxra)) {
 265                 error = VOP_BMAP(vp, lblkno, NULL, &blkno, &ncontig, NULL);
 266                 if (error)
 267                         break;
 268
 269                 if (blkno == -1)
 270                         break;
 271
 272                 /*
 273                  * We could throttle ncontig here by maxra but we might as
 274                  * well read the data if it is contiguous.  We're throttled
 275                  * by racluster anyway.
 276                  */
 277                 if (ncontig) {
 278                         ncontig = min(ncontig + 1, racluster);
 279                         rbp = cluster_rbuild(vp, filesize, lblkno, blkno,
 280                             size, ncontig, gbflags, NULL);
 281                         lblkno += (rbp->b_bufsize / size);
 282                         if (rbp->b_flags & B_DELWRI) {
 283                                 bqrelse(rbp);
 284                                 continue;
 285                         }
 286                 } else {
 287                         rbp = getblk(vp, lblkno, size, 0, 0, gbflags);
 288                         lblkno += 1;
 289                         if (rbp->b_flags & B_DELWRI) {
 290                                 bqrelse(rbp);
 291                                 continue;
 292                         }
 293                         rbp->b_flags |= B_ASYNC | B_RAM;
 294                         rbp->b_iocmd = BIO_READ;
 295                         rbp->b_blkno = blkno;
 296                 }
 297                 if (rbp->b_flags & B_CACHE) {
 298                         rbp->b_flags &= ~B_ASYNC;
 299                         bqrelse(rbp);
 300                         continue;
 301                 }
 302                 if ((rbp->b_flags & B_CLUSTER) == 0) {
 303                         vfs_busy_pages(rbp, 0);
 304                 }
 305                 rbp->b_flags &= ~B_INVAL;
 306                 rbp->b_ioflags &= ~BIO_ERROR;
 307                 if ((rbp->b_flags & B_ASYNC) || rbp->b_iodone != NULL)
 308                         BUF_KERNPROC(rbp);
 309                 rbp->b_iooffset = dbtob(rbp->b_blkno);
 310                 bstrategy(rbp);
 311 #ifdef RACCT
 312                 if (racct_enable) {
 313                         PROC_LOCK(td->td_proc);
 314                         racct_add_buf(td->td_proc, rbp, 0);
 315                         PROC_UNLOCK(td->td_proc);
 316                 }
 317 #endif /* RACCT */
 318                 td->td_ru.ru_inblock++;
 319         }
 320
 321         if (reqbp) {
 322                 /*
 323                  * Like bread, always brelse() the buffer when
 324                  * returning an error.
 325                  */
 326                 error = bufwait(reqbp);
 327                 if (error != 0) {
 328                         brelse(reqbp);
 329                         *bpp = NULL;
 330                 }
 331         }
 332         return (error);
 333 }
 334
 335 /*
 336  * If blocks are contiguous on disk, use this to provide clustered
 337  * read ahead.  We will read as many blocks as possible sequentially
 338  * and then parcel them up into logical blocks in the buffer hash table.
 339  */
 340 static struct buf *
 341 cluster_rbuild(struct vnode *vp, u_quad_t filesize, daddr_t lbn,
 342     daddr_t blkno, long size, int run, int gbflags, struct buf *fbp)
 343 {
 344         struct buf *bp, *tbp;
 345         daddr_t bn;
 346         off_t off;
 347         long tinc, tsize;
 348         int i, inc, j, k, toff;
 349
 350         KASSERT(size == vp->v_mount->mnt_stat.f_iosize,
 351             ("cluster_rbuild: size %ld != f_iosize %jd\n",
 352             size, (intmax_t)vp->v_mount->mnt_stat.f_iosize));
 353
 354         /*
 355          * avoid a division
 356          */
 357         while ((u_quad_t) size * (lbn + run) > filesize) {
 358                 --run;
 359         }
 360
 361         if (fbp) {
 362                 tbp = fbp;
 363                 tbp->b_iocmd = BIO_READ;
 364         } else {
 365                 tbp = getblk(vp, lbn, size, 0, 0, gbflags);
 366                 if (tbp->b_flags & B_CACHE)
 367                         return tbp;
 368                 tbp->b_flags |= B_ASYNC | B_RAM;
 369                 tbp->b_iocmd = BIO_READ;
 370         }
 371         tbp->b_blkno = blkno;
 372         if( (tbp->b_flags & B_MALLOC) ||
 373                 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1) )
 374                 return tbp;
 375
 376         bp = uma_zalloc(cluster_pbuf_zone, M_NOWAIT);
 377         if (bp == NULL)
 378                 return tbp;
 379         MPASS((bp->b_flags & B_MAXPHYS) != 0);
 380
 381         /*
 382          * We are synthesizing a buffer out of vm_page_t's, but
 383          * if the block size is not page aligned then the starting
 384          * address may not be either.  Inherit the b_data offset
 385          * from the original buffer.
 386          */
 387         bp->b_flags = B_ASYNC | B_CLUSTER | B_VMIO;
 388         if ((gbflags & GB_UNMAPPED) != 0) {
 389                 bp->b_data = unmapped_buf;
 390         } else {
 391                 bp->b_data = (char *)((vm_offset_t)bp->b_data |
 392                     ((vm_offset_t)tbp->b_data & PAGE_MASK));
 393         }
 394         bp->b_iocmd = BIO_READ;
 395         bp->b_iodone = cluster_callback;
 396         bp->b_blkno = blkno;
 397         bp->b_lblkno = lbn;
 398         bp->b_offset = tbp->b_offset;
 399         KASSERT(bp->b_offset != NOOFFSET, ("cluster_rbuild: no buffer offset"));
 400         pbgetvp(vp, bp);
 401
 402         TAILQ_INIT(&bp->b_cluster.cluster_head);
 403
 404         bp->b_bcount = 0;
 405         bp->b_bufsize = 0;
 406         bp->b_npages = 0;
 407
 408         inc = btodb(size);
 409         for (bn = blkno, i = 0; i < run; ++i, bn += inc) {
 410                 if (i == 0) {
 411                         vm_object_pip_add(tbp->b_bufobj->bo_object,
 412                             tbp->b_npages);
 413                         vfs_busy_pages_acquire(tbp);
 414                 } else {
 415                         if ((bp->b_npages * PAGE_SIZE) +
 416                             round_page(size) > vp->v_mount->mnt_iosize_max) {
 417                                 break;
 418                         }
 419
 420                         tbp = getblk(vp, lbn + i, size, 0, 0, GB_LOCK_NOWAIT |
 421                             (gbflags & GB_UNMAPPED));
 422
 423                         /* Don't wait around for locked bufs. */
 424                         if (tbp == NULL)
 425                                 break;
 426
 427                         /*
 428                          * Stop scanning if the buffer is fully valid
 429                          * (marked B_CACHE), or locked (may be doing a
 430                          * background write), or if the buffer is not
 431                          * VMIO backed.  The clustering code can only deal
 432                          * with VMIO-backed buffers.  The bo lock is not
 433                          * required for the BKGRDINPROG check since it
 434                          * can not be set without the buf lock.
 435                          */
 436                         if ((tbp->b_vflags & BV_BKGRDINPROG) ||
 437                             (tbp->b_flags & B_CACHE) ||
 438                             (tbp->b_flags & B_VMIO) == 0) {
 439                                 bqrelse(tbp);
 440                                 break;
 441                         }
 442
 443                         /*
 444                          * The buffer must be completely invalid in order to
 445                          * take part in the cluster.  If it is partially valid
 446                          * then we stop.
 447                          */
 448                         off = tbp->b_offset;
 449                         tsize = size;
 450                         for (j = 0; tsize > 0; j++) {
 451                                 toff = off & PAGE_MASK;
 452                                 tinc = tsize;
 453                                 if (toff + tinc > PAGE_SIZE)
 454                                         tinc = PAGE_SIZE - toff;
 455                                 if (vm_page_trysbusy(tbp->b_pages[j]) == 0)
 456                                         break;
 457                                 if ((tbp->b_pages[j]->valid &
 458                                     vm_page_bits(toff, tinc)) != 0) {
 459                                         vm_page_sunbusy(tbp->b_pages[j]);
 460                                         break;
 461                                 }
 462                                 vm_object_pip_add(tbp->b_bufobj->bo_object, 1);
 463                                 off += tinc;
 464                                 tsize -= tinc;
 465                         }
 466                         if (tsize > 0) {
 467 clean_sbusy:
 468                                 vm_object_pip_wakeupn(tbp->b_bufobj->bo_object,
 469                                     j);
 470                                 for (k = 0; k < j; k++)
 471                                         vm_page_sunbusy(tbp->b_pages[k]);
 472                                 bqrelse(tbp);
 473                                 break;
 474                         }
 475
 476                         /*
 477                          * Set a read-ahead mark as appropriate
 478                          */
 479                         if ((fbp && (i == 1)) || (i == (run - 1)))
 480                                 tbp->b_flags |= B_RAM;
 481
 482                         /*
 483                          * Set the buffer up for an async read (XXX should
 484                          * we do this only if we do not wind up brelse()ing?).
 485                          * Set the block number if it isn't set, otherwise
 486                          * if it is make sure it matches the block number we
 487                          * expect.
 488                          */
 489                         tbp->b_flags |= B_ASYNC;
 490                         tbp->b_iocmd = BIO_READ;
 491                         if (tbp->b_blkno == tbp->b_lblkno) {
 492                                 tbp->b_blkno = bn;
 493                         } else if (tbp->b_blkno != bn) {
 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                 for (j = 0; j < tbp->b_npages; j += 1) {
 505                         vm_page_t m;
 506
 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 (vm_page_all_valid(m))
 514                                 tbp->b_pages[j] = bogus_page;
 515                 }
 516
 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         for (j = 0; j < bp->b_npages; j++) {
 535                 if (vm_page_all_valid(bp->b_pages[j]))
 536                         bp->b_pages[j] = bogus_page;
 537         }
 538         if (bp->b_bufsize > bp->b_kvasize)
 539                 panic("cluster_rbuild: b_bufsize(%ld) > b_kvasize(%d)\n",
 540                     bp->b_bufsize, bp->b_kvasize);
 541
 542         if (buf_mapped(bp)) {
 543                 pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
 544                     (vm_page_t *)bp->b_pages, bp->b_npages);
 545         }
 546         return (bp);
 547 }
 548
 549 /*
 550  * Cleanup after a clustered read or write.
 551  * This is complicated by the fact that any of the buffers might have
 552  * extra memory (if there were no empty buffer headers at allocbuf time)
 553  * that we will need to shift around.
 554  */
 555 static void
 556 cluster_callback(struct buf *bp)
 557 {
 558         struct buf *nbp, *tbp;
 559         int error = 0;
 560
 561         /*
 562          * Must propagate errors to all the components.
 563          */
 564         if (bp->b_ioflags & BIO_ERROR)
 565                 error = bp->b_error;
 566
 567         if (buf_mapped(bp)) {
 568                 pmap_qremove(trunc_page((vm_offset_t) bp->b_data),
 569                     bp->b_npages);
 570         }
 571         /*
 572          * Move memory from the large cluster buffer into the component
 573          * buffers and mark IO as done on these.
 574          */
 575         for (tbp = TAILQ_FIRST(&bp->b_cluster.cluster_head);
 576                 tbp; tbp = nbp) {
 577                 nbp = TAILQ_NEXT(&tbp->b_cluster, cluster_entry);
 578                 if (error) {
 579                         tbp->b_ioflags |= BIO_ERROR;
 580                         tbp->b_error = error;
 581                 } else {
 582                         tbp->b_dirtyoff = tbp->b_dirtyend = 0;
 583                         tbp->b_flags &= ~B_INVAL;
 584                         tbp->b_ioflags &= ~BIO_ERROR;
 585                         /*
 586                          * XXX the bdwrite()/bqrelse() issued during
 587                          * cluster building clears B_RELBUF (see bqrelse()
 588                          * comment).  If direct I/O was specified, we have
 589                          * to restore it here to allow the buffer and VM
 590                          * to be freed.
 591                          */
 592                         if (tbp->b_flags & B_DIRECT)
 593                                 tbp->b_flags |= B_RELBUF;
 594                 }
 595                 bufdone(tbp);
 596         }
 597         pbrelvp(bp);
 598         uma_zfree(cluster_pbuf_zone, bp);
 599 }
 600
 601 /*
 602  *      cluster_wbuild_wb:
 603  *
 604  *      Implement modified write build for cluster.
 605  *
 606  *              write_behind = 0        write behind disabled
 607  *              write_behind = 1        write behind normal (default)
 608  *              write_behind = 2        write behind backed-off
 609  */
 610
 611 static __inline int
 612 cluster_wbuild_wb(struct vnode *vp, long size, daddr_t start_lbn, int len,
 613     int gbflags)
 614 {
 615         int r = 0;
 616
 617         switch (write_behind) {
 618         case 2:
 619                 if (start_lbn < len)
 620                         break;
 621                 start_lbn -= len;
 622                 /* FALLTHROUGH */
 623         case 1:
 624                 r = cluster_wbuild(vp, size, start_lbn, len, gbflags);
 625                 /* FALLTHROUGH */
 626         default:
 627                 /* FALLTHROUGH */
 628                 break;
 629         }
 630         return(r);
 631 }
 632
 633 /*
 634  * Do clustered write for FFS.
 635  *
 636  * Three cases:
 637  *      1. Write is not sequential (write asynchronously)
 638  *      Write is sequential:
 639  *      2.      beginning of cluster - begin cluster
 640  *      3.      middle of a cluster - add to cluster
 641  *      4.      end of a cluster - asynchronously write cluster
 642  */
 643 void
 644 cluster_write(struct vnode *vp, struct buf *bp, u_quad_t filesize, int seqcount,
 645     int gbflags)
 646 {
 647         daddr_t lbn, pbn;
 648         int maxclen, cursize;
 649         int lblocksize;
 650         int async;
 651
 652         if (!unmapped_buf_allowed)
 653                 gbflags &= ~GB_UNMAPPED;
 654
 655         if (vp->v_type == VREG) {
 656                 async = DOINGASYNC(vp);
 657                 lblocksize = vp->v_mount->mnt_stat.f_iosize;
 658         } else {
 659                 async = 0;
 660                 lblocksize = bp->b_bufsize;
 661         }
 662         lbn = bp->b_lblkno;
 663         KASSERT(bp->b_offset != NOOFFSET, ("cluster_write: no buffer offset"));
 664
 665         /* Initialize vnode to beginning of file. */
 666         if (lbn == 0)
 667                 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0;
 668
 669         if (vp->v_clen == 0 || lbn != vp->v_lastw + 1 ||
 670             (bp->b_blkno != vp->v_lasta + btodb(lblocksize))) {
 671                 maxclen = vp->v_mount->mnt_iosize_max / lblocksize - 1;
 672                 if (vp->v_clen != 0) {
 673                         /*
 674                          * Next block is not sequential.
 675                          *
 676                          * If we are not writing at end of file, the process
 677                          * seeked to another point in the file since its last
 678                          * write, or we have reached our maximum cluster size,
 679                          * then push the previous cluster. Otherwise try
 680                          * reallocating to make it sequential.
 681                          *
 682                          * Change to algorithm: only push previous cluster if
 683                          * it was sequential from the point of view of the
 684                          * seqcount heuristic, otherwise leave the buffer
 685                          * intact so we can potentially optimize the I/O
 686                          * later on in the buf_daemon or update daemon
 687                          * flush.
 688                          */
 689                         cursize = vp->v_lastw - vp->v_cstart + 1;
 690                         if (((u_quad_t) bp->b_offset + lblocksize) != filesize ||
 691                             lbn != vp->v_lastw + 1 || vp->v_clen <= cursize) {
 692                                 if (!async && seqcount > 0) {
 693                                         cluster_wbuild_wb(vp, lblocksize,
 694                                             vp->v_cstart, cursize, gbflags);
 695                                 }
 696                         } else {
 697                                 struct buf **bpp, **endbp;
 698                                 struct cluster_save *buflist;
 699
 700                                 buflist = cluster_collectbufs(vp, bp, gbflags);
 701                                 if (buflist == NULL) {
 702                                         /*
 703                                          * Cluster build failed so just write
 704                                          * it now.
 705                                          */
 706                                         bawrite(bp);
 707                                         return;
 708                                 }
 709                                 endbp = &buflist->bs_children
 710                                     [buflist->bs_nchildren - 1];
 711                                 if (VOP_REALLOCBLKS(vp, buflist)) {
 712                                         /*
 713                                          * Failed, push the previous cluster
 714                                          * if *really* writing sequentially
 715                                          * in the logical file (seqcount > 1),
 716                                          * otherwise delay it in the hopes that
 717                                          * the low level disk driver can
 718                                          * optimize the write ordering.
 719                                          */
 720                                         for (bpp = buflist->bs_children;
 721                                              bpp < endbp; bpp++)
 722                                                 brelse(*bpp);
 723                                         free(buflist, M_SEGMENT);
 724                                         if (seqcount > 1) {
 725                                                 cluster_wbuild_wb(vp,
 726                                                     lblocksize, vp->v_cstart,
 727                                                     cursize, gbflags);
 728                                         }
 729                                 } else {
 730                                         /*
 731                                          * Succeeded, keep building cluster.
 732                                          */
 733                                         for (bpp = buflist->bs_children;
 734                                              bpp <= endbp; bpp++)
 735                                                 bdwrite(*bpp);
 736                                         free(buflist, M_SEGMENT);
 737                                         vp->v_lastw = lbn;
 738                                         vp->v_lasta = bp->b_blkno;
 739                                         return;
 740                                 }
 741                         }
 742                 }
 743                 /*
 744                  * Consider beginning a cluster. If at end of file, make
 745                  * cluster as large as possible, otherwise find size of
 746                  * existing cluster.
 747                  */
 748                 if ((vp->v_type == VREG) &&
 749                         ((u_quad_t) bp->b_offset + lblocksize) != filesize &&
 750                     (bp->b_blkno == bp->b_lblkno) &&
 751                     (VOP_BMAP(vp, lbn, NULL, &bp->b_blkno, &maxclen, NULL) ||
 752                      bp->b_blkno == -1)) {
 753                         pbn = bp->b_blkno;
 754                         bawrite(bp);
 755                         vp->v_clen = 0;
 756                         vp->v_lasta = pbn;
 757                         vp->v_cstart = lbn + 1;
 758                         vp->v_lastw = lbn;
 759                         return;
 760                 }
 761                 vp->v_clen = maxclen;
 762                 pbn = bp->b_blkno;
 763                 if (!async && maxclen == 0) {   /* I/O not contiguous */
 764                         vp->v_cstart = lbn + 1;
 765                         bawrite(bp);
 766                 } else {        /* Wait for rest of cluster */
 767                         vp->v_cstart = lbn;
 768                         bdwrite(bp);
 769                 }
 770         } else if (lbn == vp->v_cstart + vp->v_clen) {
 771                 /*
 772                  * At end of cluster, write it out if seqcount tells us we
 773                  * are operating sequentially, otherwise let the buf or
 774                  * update daemon handle it.
 775                  */
 776                 pbn = bp->b_blkno;
 777                 bdwrite(bp);
 778                 if (seqcount > 1) {
 779                         cluster_wbuild_wb(vp, lblocksize, vp->v_cstart,
 780                             vp->v_clen + 1, gbflags);
 781                 }
 782                 vp->v_clen = 0;
 783                 vp->v_cstart = lbn + 1;
 784         } else if (vm_page_count_severe()) {
 785                 /*
 786                  * We are low on memory, get it going NOW
 787                  */
 788                 pbn = bp->b_blkno;
 789                 bawrite(bp);
 790         } else {
 791                 /*
 792                  * In the middle of a cluster, so just delay the I/O for now.
 793                  */
 794                 pbn = bp->b_blkno;
 795                 bdwrite(bp);
 796         }
 797         vp->v_lastw = lbn;
 798         vp->v_lasta = pbn;
 799 }
 800
 801 /*
 802  * This is an awful lot like cluster_rbuild...wish they could be combined.
 803  * The last lbn argument is the current block on which I/O is being
 804  * performed.  Check to see that it doesn't fall in the middle of
 805  * the current block (if last_bp == NULL).
 806  */
 807 int
 808 cluster_wbuild(struct vnode *vp, long size, daddr_t start_lbn, int len,
 809     int gbflags)
 810 {
 811         struct buf *bp, *tbp;
 812         struct bufobj *bo;
 813         int i, j;
 814         int totalwritten = 0;
 815         int dbsize = btodb(size);
 816
 817         if (!unmapped_buf_allowed)
 818                 gbflags &= ~GB_UNMAPPED;
 819
 820         bo = &vp->v_bufobj;
 821         while (len > 0) {
 822                 /*
 823                  * If the buffer is not delayed-write (i.e. dirty), or it
 824                  * is delayed-write but either locked or inval, it cannot
 825                  * partake in the clustered write.
 826                  */
 827                 BO_LOCK(bo);
 828                 if ((tbp = gbincore(&vp->v_bufobj, start_lbn)) == NULL ||
 829                     (tbp->b_vflags & BV_BKGRDINPROG)) {
 830                         BO_UNLOCK(bo);
 831                         ++start_lbn;
 832                         --len;
 833                         continue;
 834                 }
 835                 if (BUF_LOCK(tbp,
 836                     LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, BO_LOCKPTR(bo))) {
 837                         ++start_lbn;
 838                         --len;
 839                         continue;
 840                 }
 841                 if ((tbp->b_flags & (B_INVAL | B_DELWRI)) != B_DELWRI) {
 842                         BUF_UNLOCK(tbp);
 843                         ++start_lbn;
 844                         --len;
 845                         continue;
 846                 }
 847                 bremfree(tbp);
 848                 tbp->b_flags &= ~B_DONE;
 849
 850                 /*
 851                  * Extra memory in the buffer, punt on this buffer.
 852                  * XXX we could handle this in most cases, but we would
 853                  * have to push the extra memory down to after our max
 854                  * possible cluster size and then potentially pull it back
 855                  * up if the cluster was terminated prematurely--too much
 856                  * hassle.
 857                  */
 858                 if (((tbp->b_flags & (B_CLUSTEROK | B_MALLOC | B_VMIO)) !=
 859                      (B_CLUSTEROK | B_VMIO)) ||
 860                   (tbp->b_bcount != tbp->b_bufsize) ||
 861                   (tbp->b_bcount != size) ||
 862                   (len == 1) ||
 863                   ((bp = uma_zalloc(cluster_pbuf_zone, M_NOWAIT)) == NULL)) {
 864                         totalwritten += tbp->b_bufsize;
 865                         bawrite(tbp);
 866                         ++start_lbn;
 867                         --len;
 868                         continue;
 869                 }
 870                 MPASS((bp->b_flags & B_MAXPHYS) != 0);
 871
 872                 /*
 873                  * We got a pbuf to make the cluster in.
 874                  * so initialise it.
 875                  */
 876                 TAILQ_INIT(&bp->b_cluster.cluster_head);
 877                 bp->b_bcount = 0;
 878                 bp->b_bufsize = 0;
 879                 bp->b_npages = 0;
 880                 if (tbp->b_wcred != NOCRED)
 881                         bp->b_wcred = crhold(tbp->b_wcred);
 882
 883                 bp->b_blkno = tbp->b_blkno;
 884                 bp->b_lblkno = tbp->b_lblkno;
 885                 bp->b_offset = tbp->b_offset;
 886
 887                 /*
 888                  * We are synthesizing a buffer out of vm_page_t's, but
 889                  * if the block size is not page aligned then the starting
 890                  * address may not be either.  Inherit the b_data offset
 891                  * from the original buffer.
 892                  */
 893                 if ((gbflags & GB_UNMAPPED) == 0 ||
 894                     (tbp->b_flags & B_VMIO) == 0) {
 895                         bp->b_data = (char *)((vm_offset_t)bp->b_data |
 896                             ((vm_offset_t)tbp->b_data & PAGE_MASK));
 897                 } else {
 898                         bp->b_data = unmapped_buf;
 899                 }
 900                 bp->b_flags |= B_CLUSTER | (tbp->b_flags & (B_VMIO |
 901                     B_NEEDCOMMIT));
 902                 bp->b_iodone = cluster_callback;
 903                 pbgetvp(vp, bp);
 904                 /*
 905                  * From this location in the file, scan forward to see
 906                  * if there are buffers with adjacent data that need to
 907                  * be written as well.
 908                  */
 909                 for (i = 0; i < len; ++i, ++start_lbn) {
 910                         if (i != 0) { /* If not the first buffer */
 911                                 /*
 912                                  * If the adjacent data is not even in core it
 913                                  * can't need to be written.
 914                                  */
 915                                 BO_LOCK(bo);
 916                                 if ((tbp = gbincore(bo, start_lbn)) == NULL ||
 917                                     (tbp->b_vflags & BV_BKGRDINPROG)) {
 918                                         BO_UNLOCK(bo);
 919                                         break;
 920                                 }
 921
 922                                 /*
 923                                  * If it IS in core, but has different
 924                                  * characteristics, or is locked (which
 925                                  * means it could be undergoing a background
 926                                  * I/O or be in a weird state), then don't
 927                                  * cluster with it.
 928                                  */
 929                                 if (BUF_LOCK(tbp,
 930                                     LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK,
 931                                     BO_LOCKPTR(bo)))
 932                                         break;
 933
 934                                 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK |
 935                                     B_INVAL | B_DELWRI | B_NEEDCOMMIT))
 936                                     != (B_DELWRI | B_CLUSTEROK |
 937                                     (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) ||
 938                                     tbp->b_wcred != bp->b_wcred) {
 939                                         BUF_UNLOCK(tbp);
 940                                         break;
 941                                 }
 942
 943                                 /*
 944                                  * Check that the combined cluster
 945                                  * would make sense with regard to pages
 946                                  * and would not be too large
 947                                  */
 948                                 if ((tbp->b_bcount != size) ||
 949                                   ((bp->b_blkno + (dbsize * i)) !=
 950                                     tbp->b_blkno) ||
 951                                   ((tbp->b_npages + bp->b_npages) >
 952                                     (vp->v_mount->mnt_iosize_max / PAGE_SIZE))) {
 953                                         BUF_UNLOCK(tbp);
 954                                         break;
 955                                 }
 956
 957                                 /*
 958                                  * Ok, it's passed all the tests,
 959                                  * so remove it from the free list
 960                                  * and mark it busy. We will use it.
 961                                  */
 962                                 bremfree(tbp);
 963                                 tbp->b_flags &= ~B_DONE;
 964                         } /* end of code for non-first buffers only */
 965                         /*
 966                          * If the IO is via the VM then we do some
 967                          * special VM hackery (yuck).  Since the buffer's
 968                          * block size may not be page-aligned it is possible
 969                          * for a page to be shared between two buffers.  We
 970                          * have to get rid of the duplication when building
 971                          * the cluster.
 972                          */
 973                         if (tbp->b_flags & B_VMIO) {
 974                                 vm_page_t m;
 975
 976                                 if (i == 0) {
 977                                         vfs_busy_pages_acquire(tbp);
 978                                 } else { /* if not first buffer */
 979                                         for (j = 0; j < tbp->b_npages; j += 1) {
 980                                                 m = tbp->b_pages[j];
 981                                                 if (vm_page_trysbusy(m) == 0) {
 982                                                         for (j--; j >= 0; j--)
 983                                                                 vm_page_sunbusy(
 984                                                                     tbp->b_pages[j]);
 985                                                         bqrelse(tbp);
 986                                                         goto finishcluster;
 987                                                 }
 988                                         }
 989                                 }
 990                                 vm_object_pip_add(tbp->b_bufobj->bo_object,
 991                                     tbp->b_npages);
 992                                 for (j = 0; j < tbp->b_npages; j += 1) {
 993                                         m = tbp->b_pages[j];
 994                                         if ((bp->b_npages == 0) ||
 995                                           (bp->b_pages[bp->b_npages - 1] != m)) {
 996                                                 bp->b_pages[bp->b_npages] = m;
 997                                                 bp->b_npages++;
 998                                         }
 999                                 }
1000                         }
1001                         bp->b_bcount += size;
1002                         bp->b_bufsize += size;
1003                         /*
1004                          * If any of the clustered buffers have their
1005                          * B_BARRIER flag set, transfer that request to
1006                          * the cluster.
1007                          */
1008                         bp->b_flags |= (tbp->b_flags & B_BARRIER);
1009                         tbp->b_flags &= ~(B_DONE | B_BARRIER);
1010                         tbp->b_flags |= B_ASYNC;
1011                         tbp->b_ioflags &= ~BIO_ERROR;
1012                         tbp->b_iocmd = BIO_WRITE;
1013                         bundirty(tbp);
1014                         reassignbuf(tbp);               /* put on clean list */
1015                         bufobj_wref(tbp->b_bufobj);
1016                         BUF_KERNPROC(tbp);
1017                         buf_track(tbp, __func__);
1018                         TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head,
1019                                 tbp, b_cluster.cluster_entry);
1020                 }
1021         finishcluster:
1022                 if (buf_mapped(bp)) {
1023                         pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
1024                             (vm_page_t *)bp->b_pages, bp->b_npages);
1025                 }
1026                 if (bp->b_bufsize > bp->b_kvasize)
1027                         panic(
1028                             "cluster_wbuild: b_bufsize(%ld) > b_kvasize(%d)\n",
1029                             bp->b_bufsize, bp->b_kvasize);
1030                 totalwritten += bp->b_bufsize;
1031                 bp->b_dirtyoff = 0;
1032                 bp->b_dirtyend = bp->b_bufsize;
1033                 bawrite(bp);
1034
1035                 len -= i;
1036         }
1037         return totalwritten;
1038 }
1039
1040 /*
1041  * Collect together all the buffers in a cluster.
1042  * Plus add one additional buffer.
1043  */
1044 static struct cluster_save *
1045 cluster_collectbufs(struct vnode *vp, struct buf *last_bp, int gbflags)
1046 {
1047         struct cluster_save *buflist;
1048         struct buf *bp;
1049         daddr_t lbn;
1050         int i, j, len, error;
1051
1052         len = vp->v_lastw - vp->v_cstart + 1;
1053         buflist = malloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist),
1054             M_SEGMENT, M_WAITOK);
1055         buflist->bs_nchildren = 0;
1056         buflist->bs_children = (struct buf **) (buflist + 1);
1057         for (lbn = vp->v_cstart, i = 0; i < len; lbn++, i++) {
1058                 error = bread_gb(vp, lbn, last_bp->b_bcount, NOCRED,
1059                     gbflags, &bp);
1060                 if (error != 0) {
1061                         /*
1062                          * If read fails, release collected buffers
1063                          * and return failure.
1064                          */
1065                         for (j = 0; j < i; j++)
1066                                 brelse(buflist->bs_children[j]);
1067                         free(buflist, M_SEGMENT);
1068                         return (NULL);
1069                 }
1070                 buflist->bs_children[i] = bp;
1071                 if (bp->b_blkno == bp->b_lblkno)
1072                         VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno,
1073                                 NULL, NULL);
1074         }
1075         buflist->bs_children[i] = bp = last_bp;
1076         if (bp->b_blkno == bp->b_lblkno)
1077                 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
1078         buflist->bs_nchildren = i + 1;
1079         return (buflist);
1080 }