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