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 1.36 2008/05/18 05:54:25 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                             int lblocksize);
  70 static struct buf *
  71         cluster_rbuild (struct vnode *vp, off_t filesize, off_t loffset,
  72                             off_t doffset, int size, int run,
  73                             struct buf *fbp, int doasync);
  74 static void cluster_callback (struct bio *);
  75
  76
  77 static int write_behind = 1;
  78 SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0, "");
  79
  80 extern vm_page_t        bogus_page;
  81
  82 extern int cluster_pbuf_freecnt;
  83
  84 /*
  85  * Maximum number of blocks for read-ahead.
  86  */
  87 #define MAXRA 32
  88
  89 /*
  90  * This replaces bread.
  91  */
  92 int
  93 cluster_read(struct vnode *vp, off_t filesize, off_t loffset,
  94              int size, int totread, int seqcount, struct buf **bpp)
  95 {
  96         struct buf *bp, *rbp, *reqbp;
  97         off_t origoffset;
  98         off_t doffset;
  99         int error;
 100         int i;
 101         int maxra, racluster;
 102
 103         error = 0;
 104
 105         /*
 106          * Try to limit the amount of read-ahead by a few
 107          * ad-hoc parameters.  This needs work!!!
 108          */
 109         racluster = vmaxiosize(vp) / size;
 110         maxra = 2 * racluster + (totread / size);
 111         if (maxra > MAXRA)
 112                 maxra = MAXRA;
 113         if (maxra > nbuf/8)
 114                 maxra = nbuf/8;
 115
 116         /*
 117          * get the requested block
 118          */
 119         *bpp = reqbp = bp = getblk(vp, loffset, size, 0, 0);
 120         origoffset = loffset;
 121
 122         /*
 123          * if it is in the cache, then check to see if the reads have been
 124          * sequential.  If they have, then try some read-ahead, otherwise
 125          * back-off on prospective read-aheads.
 126          */
 127         if (bp->b_flags & B_CACHE) {
 128                 if (!seqcount) {
 129                         return 0;
 130                 } else if ((bp->b_flags & B_RAM) == 0) {
 131                         return 0;
 132                 } else {
 133                         struct buf *tbp;
 134                         bp->b_flags &= ~B_RAM;
 135                         /*
 136                          * We do the crit here so that there is no window
 137                          * between the findblk and the b_usecount increment
 138                          * below.  We opt to keep the crit out of the loop
 139                          * for efficiency.
 140                          */
 141                         crit_enter();
 142                         for (i = 1; i < maxra; i++) {
 143                                 if (!(tbp = findblk(vp, loffset + i * size))) {
 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                         loffset += i * size;
 160                 }
 161                 reqbp = bp = NULL;
 162         } else {
 163                 off_t firstread = bp->b_loffset;
 164                 int nblks;
 165
 166                 KASSERT(firstread != NOOFFSET,
 167                         ("cluster_read: no buffer offset"));
 168                 if (firstread + totread > filesize)
 169                         totread = (int)(filesize - firstread);
 170                 nblks = totread / size;
 171                 if (nblks) {
 172                         int burstbytes;
 173
 174                         if (nblks > racluster)
 175                                 nblks = racluster;
 176
 177                         error = VOP_BMAP(vp, loffset,
 178                                          &doffset, &burstbytes, NULL);
 179                         if (error)
 180                                 goto single_block_read;
 181                         if (doffset == NOOFFSET)
 182                                 goto single_block_read;
 183                         if (burstbytes < size * 2)
 184                                 goto single_block_read;
 185                         if (nblks > burstbytes / size)
 186                                 nblks = burstbytes / size;
 187
 188                         bp = cluster_rbuild(vp, filesize, loffset,
 189                                             doffset, size, nblks, bp, 0);
 190                         loffset += bp->b_bufsize;
 191                 } else {
 192 single_block_read:
 193                         /*
 194                          * if it isn't in the cache, then get a chunk from
 195                          * disk if sequential, otherwise just get the block.
 196                          */
 197                         bp->b_flags |= B_RAM;
 198                         loffset += size;
 199                 }
 200         }
 201
 202         /*
 203          * Handle the synchronous read.  This only occurs if B_CACHE was
 204          * not set.  bp (and rbp) could be either a cluster bp or a normal
 205          * bp depending on the what cluster_rbuild() decided to do.  If
 206          * it is a cluster bp, vfs_busy_pages() has already been called.
 207          */
 208         if (bp) {
 209 #if defined(CLUSTERDEBUG)
 210                 if (rcluster)
 211                         kprintf("S(%lld,%d,%d) ",
 212                             bp->b_loffset, bp->b_bcount, seqcount);
 213 #endif
 214                 bp->b_cmd = BUF_CMD_READ;
 215                 if ((bp->b_flags & B_CLUSTER) == 0)
 216                         vfs_busy_pages(vp, bp);
 217                 bp->b_flags &= ~(B_ERROR|B_INVAL);
 218                 if ((bp->b_flags & B_ASYNC) || bp->b_bio1.bio_done != NULL)
 219                         BUF_KERNPROC(bp);
 220                 vn_strategy(vp, &bp->b_bio1);
 221                 error = bp->b_error;
 222         }
 223
 224         /*
 225          * If we have been doing sequential I/O, then do some read-ahead.
 226          *
 227          * Only mess with buffers which we can immediately lock.  HAMMER
 228          * will do device-readahead irrespective of what the blocks
 229          * represent.
 230          */
 231         rbp = NULL;
 232         if (!error &&
 233             seqcount &&
 234             loffset < origoffset + seqcount * size &&
 235             loffset + size <= filesize
 236         ) {
 237                 int nblksread;
 238                 int ntoread;
 239                 int burstbytes;
 240
 241                 if ((rbp = findblk(vp, loffset)) != NULL) {
 242                         if (BUF_LOCK(rbp, LK_EXCLUSIVE | LK_NOWAIT)) {
 243                                 goto no_read_ahead;
 244                         }
 245                         BUF_UNLOCK(rbp);
 246                 }
 247                 rbp = getblk(vp, loffset, size, 0, 0);
 248                 if ((rbp->b_flags & B_CACHE)) {
 249                         bqrelse(rbp);
 250                         goto no_read_ahead;
 251                 }
 252
 253                 error = VOP_BMAP(vp, loffset,
 254                                  &doffset, &burstbytes, NULL);
 255                 if (error || doffset == NOOFFSET) {
 256                         rbp->b_flags |= B_INVAL;
 257                         brelse(rbp);
 258                         rbp = NULL;
 259                         goto no_read_ahead;
 260                 }
 261                 ntoread = burstbytes / size;
 262                 nblksread = (totread + size - 1) / size;
 263                 if (seqcount < nblksread)
 264                         seqcount = nblksread;
 265                 if (seqcount < ntoread)
 266                         ntoread = seqcount;
 267
 268                 rbp->b_flags |= B_RAM;
 269                 if (burstbytes) {
 270                         rbp = cluster_rbuild(vp, filesize, loffset,
 271                                              doffset, size,
 272                                              ntoread, rbp, 1);
 273                 } else {
 274                         rbp->b_bio2.bio_offset = doffset;
 275                 }
 276 #if defined(CLUSTERDEBUG)
 277                 if (rcluster) {
 278                         if (bp)
 279                                 kprintf("A+(%lld,%d,%lld,%d) ",
 280                                     rbp->b_loffset, rbp->b_bcount,
 281                                     rbp->b_loffset - origoffset,
 282                                     seqcount);
 283                         else
 284                                 kprintf("A(%lld,%d,%lld,%d) ",
 285                                     rbp->b_loffset, rbp->b_bcount,
 286                                     rbp->b_loffset - origoffset,
 287                                     seqcount);
 288                 }
 289 #endif
 290                 rbp->b_flags &= ~(B_ERROR|B_INVAL);
 291                 rbp->b_flags |= B_ASYNC;
 292                 rbp->b_cmd = BUF_CMD_READ;
 293
 294                 if ((rbp->b_flags & B_CLUSTER) == 0)
 295                         vfs_busy_pages(vp, rbp);
 296                 BUF_KERNPROC(rbp);                      /* B_ASYNC */
 297                 vn_strategy(vp, &rbp->b_bio1);
 298         }
 299 no_read_ahead:
 300
 301         if (reqbp)
 302                 return (biowait(reqbp));
 303         else
 304                 return (error);
 305 }
 306
 307 /*
 308  * If blocks are contiguous on disk, use this to provide clustered
 309  * read ahead.  We will read as many blocks as possible sequentially
 310  * and then parcel them up into logical blocks in the buffer hash table.
 311  */
 312 static struct buf *
 313 cluster_rbuild(struct vnode *vp, off_t filesize, off_t loffset,
 314         off_t doffset, int size, int run, struct buf *fbp, int doasync)
 315 {
 316         struct buf *bp, *tbp;
 317         off_t boffset;
 318         int i, j;
 319         int maxiosize = vmaxiosize(vp);
 320
 321         /*
 322          * This is a filesystem sanity check.  For regular files h
 323          * cluster_write() currently uses f_iosize, make sure cluster_read()
 324          * uses the same block size.
 325          *
 326          * NOTE: The vp can be a block device
 327          */
 328         if (vp->v_type == VREG) {
 329                 KASSERT(size == vp->v_mount->mnt_stat.f_iosize,
 330                     ("cluster_rbuild: size %d != filesize %ld\n",
 331                     size, vp->v_mount->mnt_stat.f_iosize));
 332         }
 333
 334         /*
 335          * avoid a division
 336          */
 337         while (loffset + run * size > filesize) {
 338                 --run;
 339         }
 340
 341         tbp = fbp;
 342         tbp->b_bio2.bio_offset = doffset;
 343         if((tbp->b_flags & B_MALLOC) ||
 344             ((tbp->b_flags & B_VMIO) == 0) || (run <= 1)) {
 345                 return tbp;
 346         }
 347
 348         bp = trypbuf(&cluster_pbuf_freecnt);
 349         if (bp == NULL)
 350                 return tbp;
 351
 352         /*
 353          * We are synthesizing a buffer out of vm_page_t's, but
 354          * if the block size is not page aligned then the starting
 355          * address may not be either.  Inherit the b_data offset
 356          * from the original buffer.
 357          */
 358         bp->b_data = (char *)((vm_offset_t)bp->b_data |
 359             ((vm_offset_t)tbp->b_data & PAGE_MASK));
 360         bp->b_flags |= B_ASYNC | B_CLUSTER | B_VMIO;
 361         bp->b_cmd = BUF_CMD_READ;
 362         bp->b_bio1.bio_done = cluster_callback;
 363         bp->b_bio1.bio_caller_info1.cluster_head = NULL;
 364         bp->b_bio1.bio_caller_info2.cluster_tail = NULL;
 365         bp->b_loffset = loffset;
 366         bp->b_bio2.bio_offset = NOOFFSET;
 367         KASSERT(bp->b_loffset != NOOFFSET,
 368                 ("cluster_rbuild: no buffer offset"));
 369
 370         bp->b_bcount = 0;
 371         bp->b_bufsize = 0;
 372         bp->b_xio.xio_npages = 0;
 373
 374         for (boffset = doffset, i = 0; i < run; ++i, boffset += size) {
 375                 if (i) {
 376                         if ((bp->b_xio.xio_npages * PAGE_SIZE) +
 377                             round_page(size) > maxiosize) {
 378                                 break;
 379                         }
 380
 381                         /*
 382                          * Shortcut some checks and try to avoid buffers that
 383                          * would block in the lock.  The same checks have to
 384                          * be made again after we officially get the buffer.
 385                          */
 386                         if ((tbp = findblk(vp, loffset + i * size)) != NULL) {
 387                                 if (BUF_LOCK(tbp, LK_EXCLUSIVE | LK_NOWAIT))
 388                                         break;
 389                                 BUF_UNLOCK(tbp);
 390
 391                                 for (j = 0; j < tbp->b_xio.xio_npages; j++) {
 392                                         if (tbp->b_xio.xio_pages[j]->valid)
 393                                                 break;
 394                                 }
 395
 396                                 if (j != tbp->b_xio.xio_npages)
 397                                         break;
 398
 399                                 if (tbp->b_bcount != size)
 400                                         break;
 401                         }
 402
 403                         tbp = getblk(vp, loffset + i * size, size, 0, 0);
 404
 405                         /*
 406                          * Stop scanning if the buffer is fuly valid
 407                          * (marked B_CACHE), or locked (may be doing a
 408                          * background write), or if the buffer is not
 409                          * VMIO backed.  The clustering code can only deal
 410                          * with VMIO-backed buffers.
 411                          */
 412                         if ((tbp->b_flags & (B_CACHE|B_LOCKED)) ||
 413                             (tbp->b_flags & B_VMIO) == 0 ||
 414                             (LIST_FIRST(&tbp->b_dep) != NULL &&
 415                              buf_checkread(tbp))
 416                         ) {
 417                                 bqrelse(tbp);
 418                                 break;
 419                         }
 420
 421                         /*
 422                          * The buffer must be completely invalid in order to
 423                          * take part in the cluster.  If it is partially valid
 424                          * then we stop.
 425                          */
 426                         for (j = 0;j < tbp->b_xio.xio_npages; j++) {
 427                                 if (tbp->b_xio.xio_pages[j]->valid)
 428                                         break;
 429                         }
 430                         if (j != tbp->b_xio.xio_npages) {
 431                                 bqrelse(tbp);
 432                                 break;
 433                         }
 434
 435                         /*
 436                          * Set a read-ahead mark as appropriate
 437                          */
 438                         if (i == 1 || i == (run - 1))
 439                                 tbp->b_flags |= B_RAM;
 440
 441                         /*
 442                          * Set the block number if it isn't set, otherwise
 443                          * if it is make sure it matches the block number we
 444                          * expect.
 445                          */
 446                         if (tbp->b_bio2.bio_offset == NOOFFSET) {
 447                                 tbp->b_bio2.bio_offset = boffset;
 448                         } else if (tbp->b_bio2.bio_offset != boffset) {
 449                                 brelse(tbp);
 450                                 break;
 451                         }
 452                 }
 453                 /*
 454                  * The first buffer is setup async if doasync is specified.
 455                  * All other buffers in the cluster are setup async.  This
 456                  * way the caller can decide how to deal with the requested
 457                  * buffer.
 458                  */
 459                 if (i || doasync)
 460                         tbp->b_flags |= B_ASYNC;
 461                 tbp->b_cmd = BUF_CMD_READ;
 462                 BUF_KERNPROC(tbp);
 463                 cluster_append(&bp->b_bio1, tbp);
 464                 for (j = 0; j < tbp->b_xio.xio_npages; ++j) {
 465                         vm_page_t m;
 466                         m = tbp->b_xio.xio_pages[j];
 467                         vm_page_io_start(m);
 468                         vm_object_pip_add(m->object, 1);
 469                         if ((bp->b_xio.xio_npages == 0) ||
 470                                 (bp->b_xio.xio_pages[bp->b_xio.xio_npages-1] != m)) {
 471                                 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m;
 472                                 bp->b_xio.xio_npages++;
 473                         }
 474                         if ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL)
 475                                 tbp->b_xio.xio_pages[j] = bogus_page;
 476                 }
 477                 /*
 478                  * XXX shouldn't this be += size for both, like in
 479                  * cluster_wbuild()?
 480                  *
 481                  * Don't inherit tbp->b_bufsize as it may be larger due to
 482                  * a non-page-aligned size.  Instead just aggregate using
 483                  * 'size'.
 484                  */
 485                 if (tbp->b_bcount != size)
 486                     kprintf("warning: tbp->b_bcount wrong %d vs %d\n", tbp->b_bcount, size);
 487                 if (tbp->b_bufsize != size)
 488                     kprintf("warning: tbp->b_bufsize wrong %d vs %d\n", tbp->b_bufsize, size);
 489                 bp->b_bcount += size;
 490                 bp->b_bufsize += size;
 491         }
 492
 493         /*
 494          * Fully valid pages in the cluster are already good and do not need
 495          * to be re-read from disk.  Replace the page with bogus_page
 496          */
 497         for (j = 0; j < bp->b_xio.xio_npages; j++) {
 498                 if ((bp->b_xio.xio_pages[j]->valid & VM_PAGE_BITS_ALL) ==
 499                     VM_PAGE_BITS_ALL) {
 500                         bp->b_xio.xio_pages[j] = bogus_page;
 501                 }
 502         }
 503         if (bp->b_bufsize > bp->b_kvasize) {
 504                 panic("cluster_rbuild: b_bufsize(%d) > b_kvasize(%d)",
 505                     bp->b_bufsize, bp->b_kvasize);
 506         }
 507
 508         pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
 509                 (vm_page_t *)bp->b_xio.xio_pages, bp->b_xio.xio_npages);
 510         return (bp);
 511 }
 512
 513 /*
 514  * Cleanup after a clustered read or write.
 515  * This is complicated by the fact that any of the buffers might have
 516  * extra memory (if there were no empty buffer headers at allocbuf time)
 517  * that we will need to shift around.
 518  *
 519  * The returned bio is &bp->b_bio1
 520  */
 521 void
 522 cluster_callback(struct bio *bio)
 523 {
 524         struct buf *bp = bio->bio_buf;
 525         struct buf *tbp;
 526         int error = 0;
 527
 528         /*
 529          * Must propogate errors to all the components.  A short read (EOF)
 530          * is a critical error.
 531          */
 532         if (bp->b_flags & B_ERROR) {
 533                 error = bp->b_error;
 534         } else if (bp->b_bcount != bp->b_bufsize) {
 535                 panic("cluster_callback: unexpected EOF on cluster %p!", bio);
 536         }
 537
 538         pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_xio.xio_npages);
 539         /*
 540          * Move memory from the large cluster buffer into the component
 541          * buffers and mark IO as done on these.  Since the memory map
 542          * is the same, no actual copying is required.
 543          */
 544         while ((tbp = bio->bio_caller_info1.cluster_head) != NULL) {
 545                 bio->bio_caller_info1.cluster_head = tbp->b_cluster_next;
 546                 if (error) {
 547                         tbp->b_flags |= B_ERROR;
 548                         tbp->b_error = error;
 549                 } else {
 550                         tbp->b_dirtyoff = tbp->b_dirtyend = 0;
 551                         tbp->b_flags &= ~(B_ERROR|B_INVAL);
 552                         /*
 553                          * XXX the bdwrite()/bqrelse() issued during
 554                          * cluster building clears B_RELBUF (see bqrelse()
 555                          * comment).  If direct I/O was specified, we have
 556                          * to restore it here to allow the buffer and VM
 557                          * to be freed.
 558                          */
 559                         if (tbp->b_flags & B_DIRECT)
 560                                 tbp->b_flags |= B_RELBUF;
 561                 }
 562                 biodone(&tbp->b_bio1);
 563         }
 564         relpbuf(bp, &cluster_pbuf_freecnt);
 565 }
 566
 567 /*
 568  *      cluster_wbuild_wb:
 569  *
 570  *      Implement modified write build for cluster.
 571  *
 572  *              write_behind = 0        write behind disabled
 573  *              write_behind = 1        write behind normal (default)
 574  *              write_behind = 2        write behind backed-off
 575  */
 576
 577 static __inline int
 578 cluster_wbuild_wb(struct vnode *vp, int size, off_t start_loffset, int len)
 579 {
 580         int r = 0;
 581
 582         switch(write_behind) {
 583         case 2:
 584                 if (start_loffset < len)
 585                         break;
 586                 start_loffset -= len;
 587                 /* fall through */
 588         case 1:
 589                 r = cluster_wbuild(vp, size, start_loffset, len);
 590                 /* fall through */
 591         default:
 592                 /* fall through */
 593                 break;
 594         }
 595         return(r);
 596 }
 597
 598 /*
 599  * Do clustered write for FFS.
 600  *
 601  * Three cases:
 602  *      1. Write is not sequential (write asynchronously)
 603  *      Write is sequential:
 604  *      2.      beginning of cluster - begin cluster
 605  *      3.      middle of a cluster - add to cluster
 606  *      4.      end of a cluster - asynchronously write cluster
 607  */
 608 void
 609 cluster_write(struct buf *bp, off_t filesize, int seqcount)
 610 {
 611         struct vnode *vp;
 612         off_t loffset;
 613         int maxclen, cursize;
 614         int lblocksize;
 615         int async;
 616
 617         vp = bp->b_vp;
 618         if (vp->v_type == VREG) {
 619                 async = vp->v_mount->mnt_flag & MNT_ASYNC;
 620                 lblocksize = vp->v_mount->mnt_stat.f_iosize;
 621         } else {
 622                 async = 0;
 623                 lblocksize = bp->b_bufsize;
 624         }
 625         loffset = bp->b_loffset;
 626         KASSERT(bp->b_loffset != NOOFFSET,
 627                 ("cluster_write: no buffer offset"));
 628
 629         /* Initialize vnode to beginning of file. */
 630         if (loffset == 0)
 631                 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0;
 632
 633         if (vp->v_clen == 0 || loffset != vp->v_lastw + lblocksize ||
 634             bp->b_bio2.bio_offset == NOOFFSET ||
 635             (bp->b_bio2.bio_offset != vp->v_lasta + lblocksize)) {
 636                 maxclen = vmaxiosize(vp);
 637                 if (vp->v_clen != 0) {
 638                         /*
 639                          * Next block is not sequential.
 640                          *
 641                          * If we are not writing at end of file, the process
 642                          * seeked to another point in the file since its last
 643                          * write, or we have reached our maximum cluster size,
 644                          * then push the previous cluster. Otherwise try
 645                          * reallocating to make it sequential.
 646                          *
 647                          * Change to algorithm: only push previous cluster if
 648                          * it was sequential from the point of view of the
 649                          * seqcount heuristic, otherwise leave the buffer
 650                          * intact so we can potentially optimize the I/O
 651                          * later on in the buf_daemon or update daemon
 652                          * flush.
 653                          */
 654                         cursize = vp->v_lastw - vp->v_cstart + lblocksize;
 655                         if (bp->b_loffset + lblocksize != filesize ||
 656                             loffset != vp->v_lastw + lblocksize || vp->v_clen <= cursize) {
 657                                 if (!async && seqcount > 0) {
 658                                         cluster_wbuild_wb(vp, lblocksize,
 659                                                 vp->v_cstart, cursize);
 660                                 }
 661                         } else {
 662                                 struct buf **bpp, **endbp;
 663                                 struct cluster_save *buflist;
 664
 665                                 buflist = cluster_collectbufs(vp, bp,
 666                                                               lblocksize);
 667                                 endbp = &buflist->bs_children
 668                                     [buflist->bs_nchildren - 1];
 669                                 if (VOP_REALLOCBLKS(vp, buflist)) {
 670                                         /*
 671                                          * Failed, push the previous cluster
 672                                          * if *really* writing sequentially
 673                                          * in the logical file (seqcount > 1),
 674                                          * otherwise delay it in the hopes that
 675                                          * the low level disk driver can
 676                                          * optimize the write ordering.
 677                                          */
 678                                         for (bpp = buflist->bs_children;
 679                                              bpp < endbp; bpp++)
 680                                                 brelse(*bpp);
 681                                         kfree(buflist, M_SEGMENT);
 682                                         if (seqcount > 1) {
 683                                                 cluster_wbuild_wb(vp,
 684                                                     lblocksize, vp->v_cstart,
 685                                                     cursize);
 686                                         }
 687                                 } else {
 688                                         /*
 689                                          * Succeeded, keep building cluster.
 690                                          */
 691                                         for (bpp = buflist->bs_children;
 692                                              bpp <= endbp; bpp++)
 693                                                 bdwrite(*bpp);
 694                                         kfree(buflist, M_SEGMENT);
 695                                         vp->v_lastw = loffset;
 696                                         vp->v_lasta = bp->b_bio2.bio_offset;
 697                                         return;
 698                                 }
 699                         }
 700                 }
 701                 /*
 702                  * Consider beginning a cluster. If at end of file, make
 703                  * cluster as large as possible, otherwise find size of
 704                  * existing cluster.
 705                  */
 706                 if ((vp->v_type == VREG) &&
 707                     bp->b_loffset + lblocksize != filesize &&
 708                     (bp->b_bio2.bio_offset == NOOFFSET) &&
 709                     (VOP_BMAP(vp, loffset, &bp->b_bio2.bio_offset, &maxclen, NULL) ||
 710                      bp->b_bio2.bio_offset == NOOFFSET)) {
 711                         bawrite(bp);
 712                         vp->v_clen = 0;
 713                         vp->v_lasta = bp->b_bio2.bio_offset;
 714                         vp->v_cstart = loffset + lblocksize;
 715                         vp->v_lastw = loffset;
 716                         return;
 717                 }
 718                 if (maxclen > lblocksize)
 719                         vp->v_clen = maxclen - lblocksize;
 720                 else
 721                         vp->v_clen = 0;
 722                 if (!async && vp->v_clen == 0) { /* I/O not contiguous */
 723                         vp->v_cstart = loffset + lblocksize;
 724                         bawrite(bp);
 725                 } else {        /* Wait for rest of cluster */
 726                         vp->v_cstart = loffset;
 727                         bdwrite(bp);
 728                 }
 729         } else if (loffset == vp->v_cstart + vp->v_clen) {
 730                 /*
 731                  * At end of cluster, write it out if seqcount tells us we
 732                  * are operating sequentially, otherwise let the buf or
 733                  * update daemon handle it.
 734                  */
 735                 bdwrite(bp);
 736                 if (seqcount > 1)
 737                         cluster_wbuild_wb(vp, lblocksize, vp->v_cstart,
 738                                           vp->v_clen + lblocksize);
 739                 vp->v_clen = 0;
 740                 vp->v_cstart = loffset + lblocksize;
 741         } else if (vm_page_count_severe()) {
 742                 /*
 743                  * We are low on memory, get it going NOW
 744                  */
 745                 bawrite(bp);
 746         } else {
 747                 /*
 748                  * In the middle of a cluster, so just delay the I/O for now.
 749                  */
 750                 bdwrite(bp);
 751         }
 752         vp->v_lastw = loffset;
 753         vp->v_lasta = bp->b_bio2.bio_offset;
 754 }
 755
 756
 757 /*
 758  * This is an awful lot like cluster_rbuild...wish they could be combined.
 759  * The last lbn argument is the current block on which I/O is being
 760  * performed.  Check to see that it doesn't fall in the middle of
 761  * the current block (if last_bp == NULL).
 762  */
 763 int
 764 cluster_wbuild(struct vnode *vp, int size, off_t start_loffset, int bytes)
 765 {
 766         struct buf *bp, *tbp;
 767         int i, j;
 768         int totalwritten = 0;
 769         int maxiosize = vmaxiosize(vp);
 770
 771         while (bytes > 0) {
 772                 crit_enter();
 773                 /*
 774                  * If the buffer is not delayed-write (i.e. dirty), or it
 775                  * is delayed-write but either locked or inval, it cannot
 776                  * partake in the clustered write.
 777                  */
 778                 if (((tbp = findblk(vp, start_loffset)) == NULL) ||
 779                   ((tbp->b_flags & (B_LOCKED | B_INVAL | B_DELWRI)) != B_DELWRI) ||
 780                   (LIST_FIRST(&tbp->b_dep) != NULL && buf_checkwrite(tbp)) ||
 781                   BUF_LOCK(tbp, LK_EXCLUSIVE | LK_NOWAIT)) {
 782                         start_loffset += size;
 783                         bytes -= size;
 784                         crit_exit();
 785                         continue;
 786                 }
 787                 bremfree(tbp);
 788                 KKASSERT(tbp->b_cmd == BUF_CMD_DONE);
 789                 crit_exit();
 790
 791                 /*
 792                  * Extra memory in the buffer, punt on this buffer.
 793                  * XXX we could handle this in most cases, but we would
 794                  * have to push the extra memory down to after our max
 795                  * possible cluster size and then potentially pull it back
 796                  * up if the cluster was terminated prematurely--too much
 797                  * hassle.
 798                  */
 799                 if (((tbp->b_flags & (B_CLUSTEROK|B_MALLOC)) != B_CLUSTEROK) ||
 800                   (tbp->b_bcount != tbp->b_bufsize) ||
 801                   (tbp->b_bcount != size) ||
 802                   (bytes == size) ||
 803                   ((bp = getpbuf(&cluster_pbuf_freecnt)) == NULL)) {
 804                         totalwritten += tbp->b_bufsize;
 805                         bawrite(tbp);
 806                         start_loffset += size;
 807                         bytes -= size;
 808                         continue;
 809                 }
 810
 811                 /*
 812                  * Set up the pbuf.  Track our append point with b_bcount
 813                  * and b_bufsize.  b_bufsize is not used by the device but
 814                  * our caller uses it to loop clusters and we use it to
 815                  * detect a premature EOF on the block device.
 816                  */
 817                 bp->b_bcount = 0;
 818                 bp->b_bufsize = 0;
 819                 bp->b_xio.xio_npages = 0;
 820                 bp->b_loffset = tbp->b_loffset;
 821                 bp->b_bio2.bio_offset = tbp->b_bio2.bio_offset;
 822
 823                 /*
 824                  * We are synthesizing a buffer out of vm_page_t's, but
 825                  * if the block size is not page aligned then the starting
 826                  * address may not be either.  Inherit the b_data offset
 827                  * from the original buffer.
 828                  */
 829                 bp->b_data = (char *)((vm_offset_t)bp->b_data |
 830                     ((vm_offset_t)tbp->b_data & PAGE_MASK));
 831                 bp->b_flags &= ~B_ERROR;
 832                 bp->b_flags |= B_CLUSTER | B_BNOCLIP |
 833                         (tbp->b_flags & (B_VMIO | B_NEEDCOMMIT));
 834                 bp->b_bio1.bio_done = cluster_callback;
 835                 bp->b_bio1.bio_caller_info1.cluster_head = NULL;
 836                 bp->b_bio1.bio_caller_info2.cluster_tail = NULL;
 837                 /*
 838                  * From this location in the file, scan forward to see
 839                  * if there are buffers with adjacent data that need to
 840                  * be written as well.
 841                  */
 842                 for (i = 0; i < bytes; (i += size), (start_loffset += size)) {
 843                         if (i != 0) { /* If not the first buffer */
 844                                 crit_enter();
 845                                 /*
 846                                  * If the adjacent data is not even in core it
 847                                  * can't need to be written.
 848                                  */
 849                                 if ((tbp = findblk(vp, start_loffset)) == NULL) {
 850                                         crit_exit();
 851                                         break;
 852                                 }
 853
 854                                 /*
 855                                  * If it IS in core, but has different
 856                                  * characteristics, or is locked (which
 857                                  * means it could be undergoing a background
 858                                  * I/O or be in a weird state), then don't
 859                                  * cluster with it.
 860                                  */
 861                                 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK |
 862                                     B_INVAL | B_DELWRI | B_NEEDCOMMIT))
 863                                   != (B_DELWRI | B_CLUSTEROK |
 864                                     (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) ||
 865                                     (tbp->b_flags & B_LOCKED) ||
 866                   (LIST_FIRST(&tbp->b_dep) != NULL && buf_checkwrite(tbp)) ||
 867                                     BUF_LOCK(tbp, LK_EXCLUSIVE | LK_NOWAIT)) {
 868                                         crit_exit();
 869                                         break;
 870                                 }
 871
 872                                 /*
 873                                  * Check that the combined cluster
 874                                  * would make sense with regard to pages
 875                                  * and would not be too large
 876                                  */
 877                                 if ((tbp->b_bcount != size) ||
 878                                   ((bp->b_bio2.bio_offset + i) !=
 879                                     tbp->b_bio2.bio_offset) ||
 880                                   ((tbp->b_xio.xio_npages + bp->b_xio.xio_npages) >
 881                                     (maxiosize / PAGE_SIZE))) {
 882                                         BUF_UNLOCK(tbp);
 883                                         crit_exit();
 884                                         break;
 885                                 }
 886                                 /*
 887                                  * Ok, it's passed all the tests,
 888                                  * so remove it from the free list
 889                                  * and mark it busy. We will use it.
 890                                  */
 891                                 bremfree(tbp);
 892                                 KKASSERT(tbp->b_cmd == BUF_CMD_DONE);
 893                                 crit_exit();
 894                         } /* end of code for non-first buffers only */
 895
 896                         /*
 897                          * If the IO is via the VM then we do some
 898                          * special VM hackery (yuck).  Since the buffer's
 899                          * block size may not be page-aligned it is possible
 900                          * for a page to be shared between two buffers.  We
 901                          * have to get rid of the duplication when building
 902                          * the cluster.
 903                          */
 904                         if (tbp->b_flags & B_VMIO) {
 905                                 vm_page_t m;
 906
 907                                 if (i != 0) { /* if not first buffer */
 908                                         for (j = 0; j < tbp->b_xio.xio_npages; ++j) {
 909                                                 m = tbp->b_xio.xio_pages[j];
 910                                                 if (m->flags & PG_BUSY) {
 911                                                         bqrelse(tbp);
 912                                                         goto finishcluster;
 913                                                 }
 914                                         }
 915                                 }
 916
 917                                 for (j = 0; j < tbp->b_xio.xio_npages; ++j) {
 918                                         m = tbp->b_xio.xio_pages[j];
 919                                         vm_page_io_start(m);
 920                                         vm_object_pip_add(m->object, 1);
 921                                         if ((bp->b_xio.xio_npages == 0) ||
 922                                           (bp->b_xio.xio_pages[bp->b_xio.xio_npages - 1] != m)) {
 923                                                 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m;
 924                                                 bp->b_xio.xio_npages++;
 925                                         }
 926                                 }
 927                         }
 928                         bp->b_bcount += size;
 929                         bp->b_bufsize += size;
 930
 931                         crit_enter();
 932                         bundirty(tbp);
 933                         tbp->b_flags &= ~B_ERROR;
 934                         tbp->b_flags |= B_ASYNC;
 935                         tbp->b_cmd = BUF_CMD_WRITE;
 936                         crit_exit();
 937                         BUF_KERNPROC(tbp);
 938                         cluster_append(&bp->b_bio1, tbp);
 939
 940                         /*
 941                          * check for latent dependencies to be handled
 942                          */
 943                         if (LIST_FIRST(&tbp->b_dep) != NULL)
 944                                 buf_start(tbp);
 945                 }
 946         finishcluster:
 947                 pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
 948                         (vm_page_t *) bp->b_xio.xio_pages, bp->b_xio.xio_npages);
 949                 if (bp->b_bufsize > bp->b_kvasize) {
 950                         panic(
 951                             "cluster_wbuild: b_bufsize(%d) > b_kvasize(%d)\n",
 952                             bp->b_bufsize, bp->b_kvasize);
 953                 }
 954                 totalwritten += bp->b_bufsize;
 955                 bp->b_dirtyoff = 0;
 956                 bp->b_dirtyend = bp->b_bufsize;
 957                 bp->b_flags |= B_ASYNC;
 958                 bp->b_cmd = BUF_CMD_WRITE;
 959                 vfs_busy_pages(vp, bp);
 960                 bp->b_runningbufspace = bp->b_bufsize;
 961                 if (bp->b_runningbufspace) {
 962                         runningbufspace += bp->b_runningbufspace;
 963                         ++runningbufcount;
 964                 }
 965                 BUF_KERNPROC(bp);       /* B_ASYNC */
 966                 vn_strategy(vp, &bp->b_bio1);
 967
 968                 bytes -= i;
 969         }
 970         return totalwritten;
 971 }
 972
 973 /*
 974  * Collect together all the buffers in a cluster.
 975  * Plus add one additional buffer.
 976  */
 977 static struct cluster_save *
 978 cluster_collectbufs(struct vnode *vp, struct buf *last_bp, int lblocksize)
 979 {
 980         struct cluster_save *buflist;
 981         struct buf *bp;
 982         off_t loffset;
 983         int i, len;
 984
 985         len = (int)(vp->v_lastw - vp->v_cstart + lblocksize) / lblocksize;
 986         buflist = kmalloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist),
 987                          M_SEGMENT, M_WAITOK);
 988         buflist->bs_nchildren = 0;
 989         buflist->bs_children = (struct buf **) (buflist + 1);
 990         for (loffset = vp->v_cstart, i = 0; i < len; (loffset += lblocksize), i++) {
 991                 (void) bread(vp, loffset, last_bp->b_bcount, &bp);
 992                 buflist->bs_children[i] = bp;
 993                 if (bp->b_bio2.bio_offset == NOOFFSET) {
 994                         VOP_BMAP(bp->b_vp, bp->b_loffset,
 995                                  &bp->b_bio2.bio_offset, NULL, NULL);
 996                 }
 997         }
 998         buflist->bs_children[i] = bp = last_bp;
 999         if (bp->b_bio2.bio_offset == NOOFFSET) {
1000                 VOP_BMAP(bp->b_vp, bp->b_loffset,
1001                          &bp->b_bio2.bio_offset, NULL, NULL);
1002         }
1003         buflist->bs_nchildren = i + 1;
1004         return (buflist);
1005 }
1006
1007 void
1008 cluster_append(struct bio *bio, struct buf *tbp)
1009 {
1010         tbp->b_cluster_next = NULL;
1011         if (bio->bio_caller_info1.cluster_head == NULL) {
1012                 bio->bio_caller_info1.cluster_head = tbp;
1013                 bio->bio_caller_info2.cluster_tail = tbp;
1014         } else {
1015                 bio->bio_caller_info2.cluster_tail->b_cluster_next = tbp;
1016                 bio->bio_caller_info2.cluster_tail = tbp;
1017         }
1018 }
1019