sys/kern/vfs_cluster.c

   1 /*-
   2  * Copyright (c) 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  * Modifications/enhancements:
   5  *      Copyright (c) 1995 John S. Dyson.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. All advertising materials mentioning features or use of this software
  16  *    must display the following acknowledgement:
  17  *      This product includes software developed by the University of
  18  *      California, Berkeley and its contributors.
  19  * 4. Neither the name of the University nor the names of its contributors
  20  *    may be used to endorse or promote products derived from this software
  21  *    without specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  33  * SUCH DAMAGE.
  34  *
  35  *      @(#)vfs_cluster.c       8.7 (Berkeley) 2/13/94
  36  * $FreeBSD: src/sys/kern/vfs_cluster.c,v 1.92.2.9 2001/11/18 07:10:59 dillon Exp $
  37  * $DragonFly: src/sys/kern/vfs_cluster.c,v 1.18 2006/03/10 17:51:54 dillon Exp $
  38  */
  39
  40 #include "opt_debug_cluster.h"
  41
  42 #include <sys/param.h>
  43 #include <sys/systm.h>
  44 #include <sys/kernel.h>
  45 #include <sys/proc.h>
  46 #include <sys/buf.h>
  47 #include <sys/vnode.h>
  48 #include <sys/malloc.h>
  49 #include <sys/mount.h>
  50 #include <sys/resourcevar.h>
  51 #include <sys/vmmeter.h>
  52 #include <vm/vm.h>
  53 #include <vm/vm_object.h>
  54 #include <vm/vm_page.h>
  55 #include <sys/sysctl.h>
  56 #include <sys/buf2.h>
  57 #include <vm/vm_page2.h>
  58
  59 #if defined(CLUSTERDEBUG)
  60 #include <sys/sysctl.h>
  61 static int      rcluster= 0;
  62 SYSCTL_INT(_debug, OID_AUTO, rcluster, CTLFLAG_RW, &rcluster, 0, "");
  63 #endif
  64
  65 static MALLOC_DEFINE(M_SEGMENT, "cluster_save", "cluster_save buffer");
  66
  67 static struct cluster_save *
  68         cluster_collectbufs (struct vnode *vp, struct buf *last_bp);
  69 static struct buf *
  70         cluster_rbuild (struct vnode *vp, u_quad_t filesize, daddr_t lbn,
  71                             daddr_t blkno, long size, int run, struct buf *fbp);
  72 static void cluster_callback (struct bio *);
  73
  74
  75 static int write_behind = 1;
  76 SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0, "");
  77
  78 extern vm_page_t        bogus_page;
  79
  80 extern int cluster_pbuf_freecnt;
  81
  82 /*
  83  * Maximum number of blocks for read-ahead.
  84  */
  85 #define MAXRA 32
  86
  87 /*
  88  * This replaces bread.
  89  */
  90 int
  91 cluster_read(struct vnode *vp, u_quad_t filesize, daddr_t lblkno,
  92         long size, long totread, int seqcount, struct buf **bpp)
  93 {
  94         struct buf *bp, *rbp, *reqbp;
  95         daddr_t blkno, origblkno;
  96         int error, num_ra;
  97         int i;
  98         int maxra, racluster;
  99         long origtotread;
 100
 101         error = 0;
 102
 103         /*
 104          * Try to limit the amount of read-ahead by a few
 105          * ad-hoc parameters.  This needs work!!!
 106          */
 107         racluster = vp->v_mount->mnt_iosize_max / size;
 108         maxra = 2 * racluster + (totread / size);
 109         if (maxra > MAXRA)
 110                 maxra = MAXRA;
 111         if (maxra > nbuf/8)
 112                 maxra = nbuf/8;
 113
 114         /*
 115          * get the requested block
 116          */
 117         *bpp = reqbp = bp = getblk(vp, lblkno, size, 0, 0);
 118         origblkno = lblkno;
 119         origtotread = totread;
 120
 121         /*
 122          * if it is in the cache, then check to see if the reads have been
 123          * sequential.  If they have, then try some read-ahead, otherwise
 124          * back-off on prospective read-aheads.
 125          */
 126         if (bp->b_flags & B_CACHE) {
 127                 if (!seqcount) {
 128                         return 0;
 129                 } else if ((bp->b_flags & B_RAM) == 0) {
 130                         return 0;
 131                 } else {
 132                         struct buf *tbp;
 133                         bp->b_flags &= ~B_RAM;
 134                         /*
 135                          * We do the crit here so that there is no window
 136                          * between the findblk and the b_usecount increment
 137                          * below.  We opt to keep the crit out of the loop
 138                          * for efficiency.
 139                          */
 140                         crit_enter();
 141                         for (i = 1; i < maxra; i++) {
 142
 143                                 if (!(tbp = findblk(vp, lblkno+i))) {
 144                                         break;
 145                                 }
 146
 147                                 /*
 148                                  * Set another read-ahead mark so we know
 149                                  * to check again.
 150                                  */
 151                                 if (((i % racluster) == (racluster - 1)) ||
 152                                         (i == (maxra - 1)))
 153                                         tbp->b_flags |= B_RAM;
 154                         }
 155                         crit_exit();
 156                         if (i >= maxra) {
 157                                 return 0;
 158                         }
 159                         lblkno += i;
 160                 }
 161                 reqbp = bp = NULL;
 162         } else {
 163                 off_t firstread = bp->b_loffset;
 164
 165                 KASSERT(firstread != NOOFFSET,
 166                         ("cluster_read: no buffer offset"));
 167                 if (firstread + totread > filesize)
 168                         totread = filesize - firstread;
 169                 if (totread > size) {
 170                         int nblks = 0;
 171                         int ncontigafter;
 172                         while (totread > 0) {
 173                                 nblks++;
 174                                 totread -= size;
 175                         }
 176                         if (nblks == 1)
 177                                 goto single_block_read;
 178                         if (nblks > racluster)
 179                                 nblks = racluster;
 180
 181                         error = VOP_BMAP(vp, lblkno, NULL,
 182                                          &blkno, &ncontigafter, NULL);
 183                         if (error)
 184                                 goto single_block_read;
 185                         if (blkno == -1)
 186                                 goto single_block_read;
 187                         if (ncontigafter == 0)
 188                                 goto single_block_read;
 189                         if (ncontigafter + 1 < nblks)
 190                                 nblks = ncontigafter + 1;
 191
 192                         bp = cluster_rbuild(vp, filesize, lblkno,
 193                                             blkno, size, nblks, bp);
 194                         lblkno += (bp->b_bufsize / size);
 195                 } else {
 196 single_block_read:
 197                         /*
 198                          * if it isn't in the cache, then get a chunk from
 199                          * disk if sequential, otherwise just get the block.
 200                          */
 201                         bp->b_flags |= B_READ | B_RAM;
 202                         lblkno += 1;
 203                 }
 204         }
 205
 206         /*
 207          * If we have been doing sequential I/O, then do some read-ahead.
 208          */
 209         rbp = NULL;
 210         if (seqcount &&
 211             lblkno < origblkno + seqcount &&
 212             (u_quad_t)(lblkno + 1) * size <= filesize
 213         ) {
 214                 rbp = getblk(vp, lblkno, size, 0, 0);
 215                 if ((rbp->b_flags & B_CACHE) == 0) {
 216                         int nblksread;
 217                         int ntoread;
 218
 219                         error = VOP_BMAP(vp, lblkno, NULL,
 220                                          &blkno, &num_ra, NULL);
 221                         if (error || blkno == (daddr_t)-1) {
 222                                 rbp->b_flags &= ~(B_ASYNC | B_READ);
 223                                 brelse(rbp);
 224                                 rbp = NULL;
 225                                 goto no_read_ahead;
 226                         }
 227                         ntoread = num_ra + 1;
 228                         nblksread = (origtotread + size - 1) / size;
 229                         if (seqcount < nblksread)
 230                                 seqcount = nblksread;
 231                         if (seqcount < ntoread)
 232                                 ntoread = seqcount;
 233
 234                         rbp->b_flags |= B_READ | B_ASYNC | B_RAM;
 235                         if (num_ra) {
 236                                 rbp = cluster_rbuild(vp, filesize, lblkno,
 237                                                      blkno, size, ntoread, rbp);
 238                         } else {
 239                                 rbp->b_bio2.bio_blkno = blkno;
 240                         }
 241                 }
 242         }
 243 no_read_ahead:
 244
 245         /*
 246          * Handle the synchronous read
 247          */
 248         if (bp) {
 249 #if defined(CLUSTERDEBUG)
 250                 if (rcluster)
 251                         printf("S(%ld,%ld,%d) ",
 252                             (long)bp->b_lblkno, bp->b_bcount, seqcount);
 253 #endif
 254                 if ((bp->b_flags & B_CLUSTER) == 0) {
 255                         vfs_busy_pages(bp, 0);
 256                 }
 257                 bp->b_flags &= ~(B_ERROR|B_INVAL);
 258                 if ((bp->b_flags & B_ASYNC) || bp->b_bio1.bio_done != NULL)
 259                         BUF_KERNPROC(bp);
 260                 vn_strategy(vp, &bp->b_bio1);
 261                 error = bp->b_error;
 262         }
 263
 264         /*
 265          * And if we have read-aheads, do them too
 266          */
 267         if (rbp) {
 268                 if (error) {
 269                         rbp->b_flags &= ~(B_ASYNC | B_READ);
 270                         brelse(rbp);
 271                 } else if (rbp->b_flags & B_CACHE) {
 272                         rbp->b_flags &= ~(B_ASYNC | B_READ);
 273                         bqrelse(rbp);
 274                 } else {
 275 #if defined(CLUSTERDEBUG)
 276                         if (rcluster) {
 277                                 if (bp)
 278                                         printf("A+(%ld,%ld,%ld,%d) ",
 279                                             (long)rbp->b_lblkno, rbp->b_bcount,
 280                                             (long)(rbp->b_lblkno - origblkno),
 281                                             seqcount);
 282                                 else
 283                                         printf("A(%ld,%ld,%ld,%d) ",
 284                                             (long)rbp->b_lblkno, rbp->b_bcount,
 285                                             (long)(rbp->b_lblkno - origblkno),
 286                                             seqcount);
 287                         }
 288 #endif
 289
 290                         if ((rbp->b_flags & B_CLUSTER) == 0) {
 291                                 vfs_busy_pages(rbp, 0);
 292                         }
 293                         rbp->b_flags &= ~(B_ERROR|B_INVAL);
 294                         if ((rbp->b_flags & B_ASYNC) || rbp->b_bio1.bio_done != NULL)
 295                                 BUF_KERNPROC(rbp);
 296                         vn_strategy(vp, &rbp->b_bio1);
 297                 }
 298         }
 299         if (reqbp)
 300                 return (biowait(reqbp));
 301         else
 302                 return (error);
 303 }
 304
 305 /*
 306  * If blocks are contiguous on disk, use this to provide clustered
 307  * read ahead.  We will read as many blocks as possible sequentially
 308  * and then parcel them up into logical blocks in the buffer hash table.
 309  */
 310 static struct buf *
 311 cluster_rbuild(struct vnode *vp, u_quad_t filesize, daddr_t lbn,
 312         daddr_t blkno, long size, int run, struct buf *fbp)
 313 {
 314         struct buf *bp, *tbp;
 315         daddr_t bn;
 316         int i, inc, j;
 317
 318         KASSERT(size == vp->v_mount->mnt_stat.f_iosize,
 319             ("cluster_rbuild: size %ld != filesize %ld\n",
 320             size, vp->v_mount->mnt_stat.f_iosize));
 321
 322         /*
 323          * avoid a division
 324          */
 325         while ((u_quad_t) size * (lbn + run) > filesize) {
 326                 --run;
 327         }
 328
 329         tbp = fbp;
 330         tbp->b_flags |= B_READ;
 331         tbp->b_bio2.bio_blkno = blkno;
 332         if( (tbp->b_flags & B_MALLOC) ||
 333                 ((tbp->b_flags & B_VMIO) == 0) || (run <= 1) )
 334                 return tbp;
 335
 336         bp = trypbuf(&cluster_pbuf_freecnt);
 337         if (bp == 0)
 338                 return tbp;
 339
 340         /*
 341          * We are synthesizing a buffer out of vm_page_t's, but
 342          * if the block size is not page aligned then the starting
 343          * address may not be either.  Inherit the b_data offset
 344          * from the original buffer.
 345          */
 346         bp->b_data = (char *)((vm_offset_t)bp->b_data |
 347             ((vm_offset_t)tbp->b_data & PAGE_MASK));
 348         bp->b_flags = B_ASYNC | B_READ | B_CLUSTER | B_VMIO;
 349         bp->b_bio1.bio_done = cluster_callback;
 350         bp->b_bio1.bio_caller_info1.cluster_head = NULL;
 351         bp->b_bio1.bio_caller_info2.cluster_tail = NULL;
 352         bp->b_lblkno = lbn;
 353         bp->b_loffset = tbp->b_loffset;
 354         bp->b_bio2.bio_blkno = (daddr_t)-1;
 355         KASSERT(bp->b_loffset != NOOFFSET,
 356                 ("cluster_rbuild: no buffer offset"));
 357         pbgetvp(vp, bp);
 358
 359         bp->b_bcount = 0;
 360         bp->b_bufsize = 0;
 361         bp->b_xio.xio_npages = 0;
 362
 363         inc = btodb(size);
 364         for (bn = blkno, i = 0; i < run; ++i, bn += inc) {
 365                 if (i != 0) {
 366                         if ((bp->b_xio.xio_npages * PAGE_SIZE) +
 367                             round_page(size) > vp->v_mount->mnt_iosize_max) {
 368                                 break;
 369                         }
 370
 371                         /*
 372                          * Shortcut some checks and try to avoid buffers that
 373                          * would block in the lock.  The same checks have to
 374                          * be made again after we officially get the buffer.
 375                          */
 376                         if ((tbp = findblk(vp, lbn + i)) != NULL) {
 377                                 if (BUF_LOCK(tbp, LK_EXCLUSIVE | LK_NOWAIT))
 378                                         break;
 379                                 BUF_UNLOCK(tbp);
 380
 381                                 for (j = 0; j < tbp->b_xio.xio_npages; j++) {
 382                                         if (tbp->b_xio.xio_pages[j]->valid)
 383                                                 break;
 384                                 }
 385
 386                                 if (j != tbp->b_xio.xio_npages)
 387                                         break;
 388
 389                                 if (tbp->b_bcount != size)
 390                                         break;
 391                         }
 392
 393                         tbp = getblk(vp, lbn + i, size, 0, 0);
 394
 395                         /*
 396                          * Stop scanning if the buffer is fuly valid
 397                          * (marked B_CACHE), or locked (may be doing a
 398                          * background write), or if the buffer is not
 399                          * VMIO backed.  The clustering code can only deal
 400                          * with VMIO-backed buffers.
 401                          */
 402                         if ((tbp->b_flags & (B_CACHE|B_LOCKED)) ||
 403                             (tbp->b_flags & B_VMIO) == 0) {
 404                                 bqrelse(tbp);
 405                                 break;
 406                         }
 407
 408                         /*
 409                          * The buffer must be completely invalid in order to
 410                          * take part in the cluster.  If it is partially valid
 411                          * then we stop.
 412                          */
 413                         for (j = 0;j < tbp->b_xio.xio_npages; j++) {
 414                                 if (tbp->b_xio.xio_pages[j]->valid)
 415                                         break;
 416                         }
 417                         if (j != tbp->b_xio.xio_npages) {
 418                                 bqrelse(tbp);
 419                                 break;
 420                         }
 421
 422                         /*
 423                          * Set a read-ahead mark as appropriate
 424                          */
 425                         if (i == 1 || i == (run - 1))
 426                                 tbp->b_flags |= B_RAM;
 427
 428                         /*
 429                          * Set the buffer up for an async read (XXX should
 430                          * we do this only if we do not wind up brelse()ing?).
 431                          * Set the block number if it isn't set, otherwise
 432                          * if it is make sure it matches the block number we
 433                          * expect.
 434                          */
 435                         tbp->b_flags |= B_READ | B_ASYNC;
 436                         if (tbp->b_bio2.bio_blkno == (daddr_t)-1) {
 437                                 tbp->b_bio2.bio_blkno = bn;
 438                         } else if (tbp->b_bio2.bio_blkno != bn) {
 439                                 brelse(tbp);
 440                                 break;
 441                         }
 442                 }
 443                 /*
 444                  * XXX fbp from caller may not be B_ASYNC, but we are going
 445                  * to biodone() it in cluster_callback() anyway
 446                  */
 447                 BUF_KERNPROC(tbp);
 448                 cluster_append(&bp->b_bio1, tbp);
 449                 for (j = 0; j < tbp->b_xio.xio_npages; j += 1) {
 450                         vm_page_t m;
 451                         m = tbp->b_xio.xio_pages[j];
 452                         vm_page_io_start(m);
 453                         vm_object_pip_add(m->object, 1);
 454                         if ((bp->b_xio.xio_npages == 0) ||
 455                                 (bp->b_xio.xio_pages[bp->b_xio.xio_npages-1] != m)) {
 456                                 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m;
 457                                 bp->b_xio.xio_npages++;
 458                         }
 459                         if ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL)
 460                                 tbp->b_xio.xio_pages[j] = bogus_page;
 461                 }
 462                 /*
 463                  * XXX shouldn't this be += size for both, like in
 464                  * cluster_wbuild()?
 465                  *
 466                  * Don't inherit tbp->b_bufsize as it may be larger due to
 467                  * a non-page-aligned size.  Instead just aggregate using
 468                  * 'size'.
 469                  */
 470                 if (tbp->b_bcount != size)
 471                     printf("warning: tbp->b_bcount wrong %ld vs %ld\n", tbp->b_bcount, size);
 472                 if (tbp->b_bufsize != size)
 473                     printf("warning: tbp->b_bufsize wrong %ld vs %ld\n", tbp->b_bufsize, size);
 474                 bp->b_bcount += size;
 475                 bp->b_bufsize += size;
 476         }
 477
 478         /*
 479          * Fully valid pages in the cluster are already good and do not need
 480          * to be re-read from disk.  Replace the page with bogus_page
 481          */
 482         for (j = 0; j < bp->b_xio.xio_npages; j++) {
 483                 if ((bp->b_xio.xio_pages[j]->valid & VM_PAGE_BITS_ALL) ==
 484                     VM_PAGE_BITS_ALL) {
 485                         bp->b_xio.xio_pages[j] = bogus_page;
 486                 }
 487         }
 488         if (bp->b_bufsize > bp->b_kvasize)
 489                 panic("cluster_rbuild: b_bufsize(%ld) > b_kvasize(%d)",
 490                     bp->b_bufsize, bp->b_kvasize);
 491         bp->b_kvasize = bp->b_bufsize;
 492
 493         pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
 494                 (vm_page_t *)bp->b_xio.xio_pages, bp->b_xio.xio_npages);
 495         return (bp);
 496 }
 497
 498 /*
 499  * Cleanup after a clustered read or write.
 500  * This is complicated by the fact that any of the buffers might have
 501  * extra memory (if there were no empty buffer headers at allocbuf time)
 502  * that we will need to shift around.
 503  *
 504  * The returned bio is &bp->b_bio1
 505  */
 506 void
 507 cluster_callback(struct bio *bio)
 508 {
 509         struct buf *bp = bio->bio_buf;
 510         struct buf *tbp;
 511         int error = 0;
 512
 513         /*
 514          * Must propogate errors to all the components.
 515          */
 516         if (bp->b_flags & B_ERROR)
 517                 error = bp->b_error;
 518
 519         pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_xio.xio_npages);
 520         /*
 521          * Move memory from the large cluster buffer into the component
 522          * buffers and mark IO as done on these.  Since the memory map
 523          * is the same, no actual copying is required.
 524          */
 525         while ((tbp = bio->bio_caller_info1.cluster_head) != NULL) {
 526                 bio->bio_caller_info1.cluster_head = tbp->b_cluster_next;
 527                 if (error) {
 528                         tbp->b_flags |= B_ERROR;
 529                         tbp->b_error = error;
 530                 } else {
 531                         tbp->b_dirtyoff = tbp->b_dirtyend = 0;
 532                         tbp->b_flags &= ~(B_ERROR|B_INVAL);
 533                         /*
 534                          * XXX the bdwrite()/bqrelse() issued during
 535                          * cluster building clears B_RELBUF (see bqrelse()
 536                          * comment).  If direct I/O was specified, we have
 537                          * to restore it here to allow the buffer and VM
 538                          * to be freed.
 539                          */
 540                         if (tbp->b_flags & B_DIRECT)
 541                                 tbp->b_flags |= B_RELBUF;
 542                 }
 543                 biodone(&tbp->b_bio1);
 544         }
 545         relpbuf(bp, &cluster_pbuf_freecnt);
 546 }
 547
 548 /*
 549  *      cluster_wbuild_wb:
 550  *
 551  *      Implement modified write build for cluster.
 552  *
 553  *              write_behind = 0        write behind disabled
 554  *              write_behind = 1        write behind normal (default)
 555  *              write_behind = 2        write behind backed-off
 556  */
 557
 558 static __inline int
 559 cluster_wbuild_wb(struct vnode *vp, long size, daddr_t start_lbn, int len)
 560 {
 561         int r = 0;
 562
 563         switch(write_behind) {
 564         case 2:
 565                 if (start_lbn < len)
 566                         break;
 567                 start_lbn -= len;
 568                 /* fall through */
 569         case 1:
 570                 r = cluster_wbuild(vp, size, start_lbn, len);
 571                 /* fall through */
 572         default:
 573                 /* fall through */
 574                 break;
 575         }
 576         return(r);
 577 }
 578
 579 /*
 580  * Do clustered write for FFS.
 581  *
 582  * Three cases:
 583  *      1. Write is not sequential (write asynchronously)
 584  *      Write is sequential:
 585  *      2.      beginning of cluster - begin cluster
 586  *      3.      middle of a cluster - add to cluster
 587  *      4.      end of a cluster - asynchronously write cluster
 588  */
 589 void
 590 cluster_write(struct buf *bp, u_quad_t filesize, int seqcount)
 591 {
 592         struct vnode *vp;
 593         daddr_t lbn;
 594         int maxclen, cursize;
 595         int lblocksize;
 596         int async;
 597
 598         vp = bp->b_vp;
 599         if (vp->v_type == VREG) {
 600                 async = vp->v_mount->mnt_flag & MNT_ASYNC;
 601                 lblocksize = vp->v_mount->mnt_stat.f_iosize;
 602         } else {
 603                 async = 0;
 604                 lblocksize = bp->b_bufsize;
 605         }
 606         lbn = bp->b_lblkno;
 607         KASSERT(bp->b_loffset != NOOFFSET,
 608                 ("cluster_write: no buffer offset"));
 609
 610         /* Initialize vnode to beginning of file. */
 611         if (lbn == 0)
 612                 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0;
 613
 614         if (vp->v_clen == 0 || lbn != vp->v_lastw + 1 ||
 615             bp->b_bio2.bio_blkno == (daddr_t)-1 ||
 616             (bp->b_bio2.bio_blkno != vp->v_lasta + btodb(lblocksize))) {
 617                 maxclen = vp->v_mount->mnt_iosize_max / lblocksize - 1;
 618                 if (vp->v_clen != 0) {
 619                         /*
 620                          * Next block is not sequential.
 621                          *
 622                          * If we are not writing at end of file, the process
 623                          * seeked to another point in the file since its last
 624                          * write, or we have reached our maximum cluster size,
 625                          * then push the previous cluster. Otherwise try
 626                          * reallocating to make it sequential.
 627                          *
 628                          * Change to algorithm: only push previous cluster if
 629                          * it was sequential from the point of view of the
 630                          * seqcount heuristic, otherwise leave the buffer
 631                          * intact so we can potentially optimize the I/O
 632                          * later on in the buf_daemon or update daemon
 633                          * flush.
 634                          */
 635                         cursize = vp->v_lastw - vp->v_cstart + 1;
 636                         if (((u_quad_t) bp->b_loffset + lblocksize) != filesize ||
 637                             lbn != vp->v_lastw + 1 || vp->v_clen <= cursize) {
 638                                 if (!async && seqcount > 0) {
 639                                         cluster_wbuild_wb(vp, lblocksize,
 640                                                 vp->v_cstart, cursize);
 641                                 }
 642                         } else {
 643                                 struct buf **bpp, **endbp;
 644                                 struct cluster_save *buflist;
 645
 646                                 buflist = cluster_collectbufs(vp, bp);
 647                                 endbp = &buflist->bs_children
 648                                     [buflist->bs_nchildren - 1];
 649                                 if (VOP_REALLOCBLKS(vp, buflist)) {
 650                                         /*
 651                                          * Failed, push the previous cluster
 652                                          * if *really* writing sequentially
 653                                          * in the logical file (seqcount > 1),
 654                                          * otherwise delay it in the hopes that
 655                                          * the low level disk driver can
 656                                          * optimize the write ordering.
 657                                          */
 658                                         for (bpp = buflist->bs_children;
 659                                              bpp < endbp; bpp++)
 660                                                 brelse(*bpp);
 661                                         free(buflist, M_SEGMENT);
 662                                         if (seqcount > 1) {
 663                                                 cluster_wbuild_wb(vp,
 664                                                     lblocksize, vp->v_cstart,
 665                                                     cursize);
 666                                         }
 667                                 } else {
 668                                         /*
 669                                          * Succeeded, keep building cluster.
 670                                          */
 671                                         for (bpp = buflist->bs_children;
 672                                              bpp <= endbp; bpp++)
 673                                                 bdwrite(*bpp);
 674                                         free(buflist, M_SEGMENT);
 675                                         vp->v_lastw = lbn;
 676                                         vp->v_lasta = bp->b_bio2.bio_blkno;
 677                                         return;
 678                                 }
 679                         }
 680                 }
 681                 /*
 682                  * Consider beginning a cluster. If at end of file, make
 683                  * cluster as large as possible, otherwise find size of
 684                  * existing cluster.
 685                  */
 686                 if ((vp->v_type == VREG) &&
 687                         ((u_quad_t) bp->b_loffset + lblocksize) != filesize &&
 688                     (bp->b_bio2.bio_blkno == (daddr_t)-1) &&
 689                     (VOP_BMAP(vp, lbn, NULL, &bp->b_bio2.bio_blkno, &maxclen, NULL) ||
 690                      bp->b_bio2.bio_blkno == (daddr_t)-1)) {
 691                         bawrite(bp);
 692                         vp->v_clen = 0;
 693                         vp->v_lasta = bp->b_bio2.bio_blkno;
 694                         vp->v_cstart = lbn + 1;
 695                         vp->v_lastw = lbn;
 696                         return;
 697                 }
 698                 vp->v_clen = maxclen;
 699                 if (!async && maxclen == 0) {   /* I/O not contiguous */
 700                         vp->v_cstart = lbn + 1;
 701                         bawrite(bp);
 702                 } else {        /* Wait for rest of cluster */
 703                         vp->v_cstart = lbn;
 704                         bdwrite(bp);
 705                 }
 706         } else if (lbn == vp->v_cstart + vp->v_clen) {
 707                 /*
 708                  * At end of cluster, write it out if seqcount tells us we
 709                  * are operating sequentially, otherwise let the buf or
 710                  * update daemon handle it.
 711                  */
 712                 bdwrite(bp);
 713                 if (seqcount > 1)
 714                         cluster_wbuild_wb(vp, lblocksize, vp->v_cstart, vp->v_clen + 1);
 715                 vp->v_clen = 0;
 716                 vp->v_cstart = lbn + 1;
 717         } else if (vm_page_count_severe()) {
 718                 /*
 719                  * We are low on memory, get it going NOW
 720                  */
 721                 bawrite(bp);
 722         } else {
 723                 /*
 724                  * In the middle of a cluster, so just delay the I/O for now.
 725                  */
 726                 bdwrite(bp);
 727         }
 728         vp->v_lastw = lbn;
 729         vp->v_lasta = bp->b_bio2.bio_blkno;
 730 }
 731
 732
 733 /*
 734  * This is an awful lot like cluster_rbuild...wish they could be combined.
 735  * The last lbn argument is the current block on which I/O is being
 736  * performed.  Check to see that it doesn't fall in the middle of
 737  * the current block (if last_bp == NULL).
 738  */
 739 int
 740 cluster_wbuild(struct vnode *vp, long size, daddr_t start_lbn, int len)
 741 {
 742         struct buf *bp, *tbp;
 743         int i, j;
 744         int totalwritten = 0;
 745         int dbsize = btodb(size);
 746
 747         while (len > 0) {
 748                 crit_enter();
 749                 /*
 750                  * If the buffer is not delayed-write (i.e. dirty), or it
 751                  * is delayed-write but either locked or inval, it cannot
 752                  * partake in the clustered write.
 753                  */
 754                 if (((tbp = findblk(vp, start_lbn)) == NULL) ||
 755                   ((tbp->b_flags & (B_LOCKED | B_INVAL | B_DELWRI)) != B_DELWRI) ||
 756                   BUF_LOCK(tbp, LK_EXCLUSIVE | LK_NOWAIT)) {
 757                         ++start_lbn;
 758                         --len;
 759                         crit_exit();
 760                         continue;
 761                 }
 762                 bremfree(tbp);
 763                 tbp->b_flags &= ~B_DONE;
 764                 crit_exit();
 765
 766                 /*
 767                  * Extra memory in the buffer, punt on this buffer.
 768                  * XXX we could handle this in most cases, but we would
 769                  * have to push the extra memory down to after our max
 770                  * possible cluster size and then potentially pull it back
 771                  * up if the cluster was terminated prematurely--too much
 772                  * hassle.
 773                  */
 774                 if (((tbp->b_flags & (B_CLUSTEROK|B_MALLOC)) != B_CLUSTEROK) ||
 775                   (tbp->b_bcount != tbp->b_bufsize) ||
 776                   (tbp->b_bcount != size) ||
 777                   (len == 1) ||
 778                   ((bp = getpbuf(&cluster_pbuf_freecnt)) == NULL)) {
 779                         totalwritten += tbp->b_bufsize;
 780                         bawrite(tbp);
 781                         ++start_lbn;
 782                         --len;
 783                         continue;
 784                 }
 785
 786                 /*
 787                  * We got a pbuf to make the cluster in.
 788                  * so initialise it.
 789                  */
 790                 bp->b_bcount = 0;
 791                 bp->b_bufsize = 0;
 792                 bp->b_xio.xio_npages = 0;
 793                 bp->b_lblkno = tbp->b_lblkno;
 794                 bp->b_loffset = tbp->b_loffset;
 795                 bp->b_bio2.bio_blkno = tbp->b_bio2.bio_blkno;
 796
 797                 /*
 798                  * We are synthesizing a buffer out of vm_page_t's, but
 799                  * if the block size is not page aligned then the starting
 800                  * address may not be either.  Inherit the b_data offset
 801                  * from the original buffer.
 802                  */
 803                 bp->b_data = (char *)((vm_offset_t)bp->b_data |
 804                     ((vm_offset_t)tbp->b_data & PAGE_MASK));
 805                 bp->b_flags |= B_CLUSTER |
 806                         (tbp->b_flags & (B_VMIO | B_NEEDCOMMIT | B_NOWDRAIN));
 807                 bp->b_bio1.bio_done = cluster_callback;
 808                 bp->b_bio1.bio_caller_info1.cluster_head = NULL;
 809                 bp->b_bio1.bio_caller_info2.cluster_tail = NULL;
 810                 pbgetvp(vp, bp);
 811                 /*
 812                  * From this location in the file, scan forward to see
 813                  * if there are buffers with adjacent data that need to
 814                  * be written as well.
 815                  */
 816                 for (i = 0; i < len; ++i, ++start_lbn) {
 817                         if (i != 0) { /* If not the first buffer */
 818                                 crit_enter();
 819                                 /*
 820                                  * If the adjacent data is not even in core it
 821                                  * can't need to be written.
 822                                  */
 823                                 if ((tbp = findblk(vp, start_lbn)) == NULL) {
 824                                         crit_exit();
 825                                         break;
 826                                 }
 827
 828                                 /*
 829                                  * If it IS in core, but has different
 830                                  * characteristics, or is locked (which
 831                                  * means it could be undergoing a background
 832                                  * I/O or be in a weird state), then don't
 833                                  * cluster with it.
 834                                  */
 835                                 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK |
 836                                     B_INVAL | B_DELWRI | B_NEEDCOMMIT))
 837                                   != (B_DELWRI | B_CLUSTEROK |
 838                                     (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) ||
 839                                     (tbp->b_flags & B_LOCKED) ||
 840                                     BUF_LOCK(tbp, LK_EXCLUSIVE | LK_NOWAIT)) {
 841                                         crit_exit();
 842                                         break;
 843                                 }
 844
 845                                 /*
 846                                  * Check that the combined cluster
 847                                  * would make sense with regard to pages
 848                                  * and would not be too large
 849                                  */
 850                                 if ((tbp->b_bcount != size) ||
 851                                   ((bp->b_bio2.bio_blkno + (dbsize * i)) !=
 852                                     tbp->b_bio2.bio_blkno) ||
 853                                   ((tbp->b_xio.xio_npages + bp->b_xio.xio_npages) >
 854                                     (vp->v_mount->mnt_iosize_max / PAGE_SIZE))) {
 855                                         BUF_UNLOCK(tbp);
 856                                         crit_exit();
 857                                         break;
 858                                 }
 859                                 /*
 860                                  * Ok, it's passed all the tests,
 861                                  * so remove it from the free list
 862                                  * and mark it busy. We will use it.
 863                                  */
 864                                 bremfree(tbp);
 865                                 tbp->b_flags &= ~B_DONE;
 866                                 crit_exit();
 867                         } /* end of code for non-first buffers only */
 868
 869                         /*
 870                          * If the IO is via the VM then we do some
 871                          * special VM hackery (yuck).  Since the buffer's
 872                          * block size may not be page-aligned it is possible
 873                          * for a page to be shared between two buffers.  We
 874                          * have to get rid of the duplication when building
 875                          * the cluster.
 876                          */
 877                         if (tbp->b_flags & B_VMIO) {
 878                                 vm_page_t m;
 879
 880                                 if (i != 0) { /* if not first buffer */
 881                                         for (j = 0; j < tbp->b_xio.xio_npages; j += 1) {
 882                                                 m = tbp->b_xio.xio_pages[j];
 883                                                 if (m->flags & PG_BUSY) {
 884                                                         bqrelse(tbp);
 885                                                         goto finishcluster;
 886                                                 }
 887                                         }
 888                                 }
 889
 890                                 for (j = 0; j < tbp->b_xio.xio_npages; j += 1) {
 891                                         m = tbp->b_xio.xio_pages[j];
 892                                         vm_page_io_start(m);
 893                                         vm_object_pip_add(m->object, 1);
 894                                         if ((bp->b_xio.xio_npages == 0) ||
 895                                           (bp->b_xio.xio_pages[bp->b_xio.xio_npages - 1] != m)) {
 896                                                 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m;
 897                                                 bp->b_xio.xio_npages++;
 898                                         }
 899                                 }
 900                         }
 901                         bp->b_bcount += size;
 902                         bp->b_bufsize += size;
 903
 904                         crit_enter();
 905                         bundirty(tbp);
 906                         tbp->b_flags &= ~(B_READ | B_DONE | B_ERROR);
 907                         tbp->b_flags |= B_ASYNC;
 908                         crit_exit();
 909                         BUF_KERNPROC(tbp);
 910                         cluster_append(&bp->b_bio1, tbp);
 911
 912                         /*
 913                          * check for latent dependencies to be handled
 914                          */
 915                         if (LIST_FIRST(&tbp->b_dep) != NULL && bioops.io_start)
 916                                 (*bioops.io_start)(tbp);
 917
 918                 }
 919         finishcluster:
 920                 pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
 921                         (vm_page_t *) bp->b_xio.xio_pages, bp->b_xio.xio_npages);
 922                 if (bp->b_bufsize > bp->b_kvasize)
 923                         panic(
 924                             "cluster_wbuild: b_bufsize(%ld) > b_kvasize(%d)\n",
 925                             bp->b_bufsize, bp->b_kvasize);
 926                 bp->b_kvasize = bp->b_bufsize;
 927                 totalwritten += bp->b_bufsize;
 928                 bp->b_dirtyoff = 0;
 929                 bp->b_dirtyend = bp->b_bufsize;
 930                 bawrite(bp);
 931
 932                 len -= i;
 933         }
 934         return totalwritten;
 935 }
 936
 937 /*
 938  * Collect together all the buffers in a cluster.
 939  * Plus add one additional buffer.
 940  */
 941 static struct cluster_save *
 942 cluster_collectbufs(struct vnode *vp, struct buf *last_bp)
 943 {
 944         struct cluster_save *buflist;
 945         struct buf *bp;
 946         daddr_t lbn;
 947         int i, len;
 948
 949         len = vp->v_lastw - vp->v_cstart + 1;
 950         buflist = malloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist),
 951             M_SEGMENT, M_WAITOK);
 952         buflist->bs_nchildren = 0;
 953         buflist->bs_children = (struct buf **) (buflist + 1);
 954         for (lbn = vp->v_cstart, i = 0; i < len; lbn++, i++) {
 955                 (void) bread(vp, lbn, last_bp->b_bcount, &bp);
 956                 buflist->bs_children[i] = bp;
 957                 if (bp->b_bio2.bio_blkno == (daddr_t)-1)
 958                         VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_bio2.bio_blkno,
 959                                 NULL, NULL);
 960         }
 961         buflist->bs_children[i] = bp = last_bp;
 962         if (bp->b_bio2.bio_blkno == (daddr_t)-1)
 963                 VOP_BMAP(bp->b_vp, bp->b_lblkno, NULL, &bp->b_bio2.bio_blkno,
 964                         NULL, NULL);
 965         buflist->bs_nchildren = i + 1;
 966         return (buflist);
 967 }
 968
 969 void
 970 cluster_append(struct bio *bio, struct buf *tbp)
 971 {
 972         tbp->b_cluster_next = NULL;
 973         if (bio->bio_caller_info1.cluster_head == NULL) {
 974                 bio->bio_caller_info1.cluster_head = tbp;
 975                 bio->bio_caller_info2.cluster_tail = tbp;
 976         } else {
 977                 bio->bio_caller_info2.cluster_tail->b_cluster_next = tbp;
 978                 bio->bio_caller_info2.cluster_tail = tbp;
 979         }
 980 }
 981