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 1.40 2008/07/14 03:09:00 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 #include <machine/limits.h>
  60
  61 #if defined(CLUSTERDEBUG)
  62 #include <sys/sysctl.h>
  63 static int      rcluster= 0;
  64 SYSCTL_INT(_debug, OID_AUTO, rcluster, CTLFLAG_RW, &rcluster, 0, "");
  65 #endif
  66
  67 static MALLOC_DEFINE(M_SEGMENT, "cluster_save", "cluster_save buffer");
  68
  69 static struct cluster_save *
  70         cluster_collectbufs (struct vnode *vp, struct buf *last_bp,
  71                             int blksize);
  72 static struct buf *
  73         cluster_rbuild (struct vnode *vp, off_t filesize, off_t loffset,
  74                             off_t doffset, int blksize, int run,
  75                             struct buf *fbp);
  76 static void cluster_callback (struct bio *);
  77 static void cluster_setram (struct buf *);
  78
  79 static int write_behind = 1;
  80 SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0, "");
  81
  82 extern vm_page_t        bogus_page;
  83
  84 extern int cluster_pbuf_freecnt;
  85
  86 /*
  87  * Maximum number of blocks for read-ahead.
  88  */
  89 #define MAXRA 32
  90
  91 /*
  92  * This replaces bread.
  93  */
  94 int
  95 cluster_read(struct vnode *vp, off_t filesize, off_t loffset,
  96              int blksize, size_t resid, int seqcount, struct buf **bpp)
  97 {
  98         struct buf *bp, *rbp, *reqbp;
  99         off_t origoffset;
 100         off_t doffset;
 101         int error;
 102         int i;
 103         int maxra, racluster;
 104         int totread;
 105
 106         error = 0;
 107         totread = (resid > INT_MAX) ? INT_MAX : (int)resid;
 108
 109         /*
 110          * racluster - calculate maximum cluster IO size (limited by
 111          *             backing block device).
 112          *
 113          * Try to limit the amount of read-ahead by a few ad-hoc parameters.
 114          * This needs work!!!
 115          *
 116          * NOTE!  The BMAP operations may involve synchronous I/O so we
 117          *        really want several cluster IOs in progress to absorb
 118          *        the time lag.
 119          */
 120         racluster = vmaxiosize(vp) / blksize;
 121         maxra = 2 * racluster + (totread / blksize);
 122         if (maxra > MAXRA)
 123                 maxra = MAXRA;
 124         if (maxra > nbuf / 8)
 125                 maxra = nbuf / 8;
 126
 127         /*
 128          * Get the requested block.
 129          */
 130         *bpp = reqbp = bp = getblk(vp, loffset, blksize, 0, 0);
 131         origoffset = loffset;
 132
 133         /*
 134          * if it is in the cache, then check to see if the reads have been
 135          * sequential.  If they have, then try some read-ahead, otherwise
 136          * back-off on prospective read-aheads.
 137          */
 138         if (bp->b_flags & B_CACHE) {
 139                 /*
 140                  * Not sequential, do not do any read-ahead
 141                  */
 142                 if (seqcount == 0 || maxra == 0)
 143                         return 0;
 144
 145                 /*
 146                  * No read-ahead mark, do not do any read-ahead
 147                  * yet.
 148                  */
 149                 if ((bp->b_flags & B_RAM) == 0)
 150                         return 0;
 151
 152                 /*
 153                  * We hit a read-ahead-mark, figure out how much read-ahead
 154                  * to do (maxra) and where to start (loffset).
 155                  *
 156                  * Shortcut the scan.  Typically the way this works is that
 157                  * we've built up all the blocks inbetween except for the
 158                  * last in previous iterations, so if the second-to-last
 159                  * block is present we just skip ahead to it.
 160                  *
 161                  * This algorithm has O(1) cpu in the steady state no
 162                  * matter how large maxra is.
 163                  */
 164                 bp->b_flags &= ~B_RAM;
 165
 166                 if (findblk(vp, loffset + (maxra - 2) * blksize, FINDBLK_TEST))
 167                         i = maxra - 1;
 168                 else
 169                         i = 1;
 170                 while (i < maxra) {
 171                         if (findblk(vp, loffset + i * blksize,
 172                                     FINDBLK_TEST) == NULL) {
 173                                 break;
 174                         }
 175                         ++i;
 176                 }
 177                 if (i >= maxra)
 178                         return 0;
 179                 maxra -= i;
 180                 loffset += i * blksize;
 181                 reqbp = bp = NULL;
 182         } else {
 183                 off_t firstread = bp->b_loffset;
 184                 int nblks;
 185
 186                 /*
 187                  * Set-up synchronous read for bp.
 188                  */
 189                 bp->b_cmd = BUF_CMD_READ;
 190                 bp->b_bio1.bio_done = biodone_sync;
 191                 bp->b_bio1.bio_flags |= BIO_SYNC;
 192
 193                 KASSERT(firstread != NOOFFSET,
 194                         ("cluster_read: no buffer offset"));
 195                 if (firstread + totread > filesize)
 196                         totread = (int)(filesize - firstread);
 197                 nblks = totread / blksize;
 198                 if (nblks) {
 199                         int burstbytes;
 200
 201                         if (nblks > racluster)
 202                                 nblks = racluster;
 203
 204                         error = VOP_BMAP(vp, loffset, &doffset,
 205                                          &burstbytes, NULL, BUF_CMD_READ);
 206                         if (error)
 207                                 goto single_block_read;
 208                         if (doffset == NOOFFSET)
 209                                 goto single_block_read;
 210                         if (burstbytes < blksize * 2)
 211                                 goto single_block_read;
 212                         if (nblks > burstbytes / blksize)
 213                                 nblks = burstbytes / blksize;
 214
 215                         bp = cluster_rbuild(vp, filesize, loffset,
 216                                             doffset, blksize, nblks, bp);
 217                         loffset += bp->b_bufsize;
 218                         maxra -= (bp->b_bufsize - blksize) / blksize;
 219                 } else {
 220 single_block_read:
 221                         /*
 222                          * if it isn't in the cache, then get a chunk from
 223                          * disk if sequential, otherwise just get the block.
 224                          */
 225                         cluster_setram(bp);
 226                         loffset += blksize;
 227                 }
 228         }
 229
 230         /*
 231          * If B_CACHE was not set issue bp.  bp will either be an
 232          * asynchronous cluster buf or a synchronous single-buf.
 233          * If it is a single buf it will be the same as reqbp.
 234          *
 235          * NOTE: Once an async cluster buf is issued bp becomes invalid.
 236          */
 237         if (bp) {
 238 #if defined(CLUSTERDEBUG)
 239                 if (rcluster)
 240                         kprintf("S(%lld,%d,%d) ",
 241                             bp->b_loffset, bp->b_bcount, seqcount);
 242 #endif
 243                 if ((bp->b_flags & B_CLUSTER) == 0)
 244                         vfs_busy_pages(vp, bp);
 245                 bp->b_flags &= ~(B_ERROR|B_INVAL);
 246                 vn_strategy(vp, &bp->b_bio1);
 247                 error = 0;
 248                 /* bp invalid now */
 249         }
 250
 251         /*
 252          * If we have been doing sequential I/O, then do some read-ahead.
 253          * The code above us should have positioned us at the next likely
 254          * offset.
 255          *
 256          * Only mess with buffers which we can immediately lock.  HAMMER
 257          * will do device-readahead irrespective of what the blocks
 258          * represent.
 259          */
 260         while (!error && seqcount && maxra > 0 &&
 261                loffset + blksize <= filesize) {
 262                 int nblksread;
 263                 int ntoread;
 264                 int burstbytes;
 265                 int tmp_error;
 266
 267                 rbp = getblk(vp, loffset, blksize,
 268                              GETBLK_SZMATCH|GETBLK_NOWAIT, 0);
 269                 if (rbp == NULL)
 270                         goto no_read_ahead;
 271                 if ((rbp->b_flags & B_CACHE)) {
 272                         bqrelse(rbp);
 273                         goto no_read_ahead;
 274                 }
 275
 276                 /*
 277                  * An error from the read-ahead bmap has nothing to do
 278                  * with the caller's original request.
 279                  */
 280                 tmp_error = VOP_BMAP(vp, loffset, &doffset,
 281                                      &burstbytes, NULL, BUF_CMD_READ);
 282                 if (tmp_error || doffset == NOOFFSET) {
 283                         rbp->b_flags |= B_INVAL;
 284                         brelse(rbp);
 285                         rbp = NULL;
 286                         goto no_read_ahead;
 287                 }
 288                 ntoread = burstbytes / blksize;
 289                 nblksread = (totread + blksize - 1) / blksize;
 290                 if (seqcount < nblksread)
 291                         seqcount = nblksread;
 292                 if (ntoread > seqcount)
 293                         ntoread = seqcount;
 294
 295                 /*
 296                  * rbp: async read
 297                  */
 298                 rbp->b_cmd = BUF_CMD_READ;
 299                 /*rbp->b_flags |= B_AGE*/;
 300                 cluster_setram(rbp);
 301
 302                 if (burstbytes) {
 303                         rbp = cluster_rbuild(vp, filesize, loffset,
 304                                              doffset, blksize,
 305                                              ntoread, rbp);
 306                 } else {
 307                         rbp->b_bio2.bio_offset = doffset;
 308                 }
 309 #if defined(CLUSTERDEBUG)
 310                 if (rcluster) {
 311                         if (bp)
 312                                 kprintf("A+(%lld,%d,%lld,%d) ",
 313                                     rbp->b_loffset, rbp->b_bcount,
 314                                     rbp->b_loffset - origoffset,
 315                                     seqcount);
 316                         else
 317                                 kprintf("A(%lld,%d,%lld,%d) ",
 318                                     rbp->b_loffset, rbp->b_bcount,
 319                                     rbp->b_loffset - origoffset,
 320                                     seqcount);
 321                 }
 322 #endif
 323                 rbp->b_flags &= ~(B_ERROR|B_INVAL);
 324
 325                 if ((rbp->b_flags & B_CLUSTER) == 0)
 326                         vfs_busy_pages(vp, rbp);
 327                 BUF_KERNPROC(rbp);
 328                 loffset += rbp->b_bufsize;
 329                 maxra -= rbp->b_bufsize / blksize;
 330                 vn_strategy(vp, &rbp->b_bio1);
 331                 /* rbp invalid now */
 332         }
 333
 334         /*
 335          * Wait for our original buffer to complete its I/O.  reqbp will
 336          * be NULL if the original buffer was B_CACHE.  We are returning
 337          * (*bpp) which is the same as reqbp when reqbp != NULL.
 338          */
 339 no_read_ahead:
 340         if (reqbp) {
 341                 KKASSERT(reqbp->b_bio1.bio_flags & BIO_SYNC);
 342                 error = biowait(&reqbp->b_bio1, "clurd");
 343         }
 344         return (error);
 345 }
 346
 347 /*
 348  * If blocks are contiguous on disk, use this to provide clustered
 349  * read ahead.  We will read as many blocks as possible sequentially
 350  * and then parcel them up into logical blocks in the buffer hash table.
 351  *
 352  * This function either returns a cluster buf or it returns fbp.  fbp is
 353  * already expected to be set up as a synchronous or asynchronous request.
 354  *
 355  * If a cluster buf is returned it will always be async.
 356  */
 357 static struct buf *
 358 cluster_rbuild(struct vnode *vp, off_t filesize, off_t loffset, off_t doffset,
 359                int blksize, int run, struct buf *fbp)
 360 {
 361         struct buf *bp, *tbp;
 362         off_t boffset;
 363         int i, j;
 364         int maxiosize = vmaxiosize(vp);
 365
 366         /*
 367          * avoid a division
 368          */
 369         while (loffset + run * blksize > filesize) {
 370                 --run;
 371         }
 372
 373         tbp = fbp;
 374         tbp->b_bio2.bio_offset = doffset;
 375         if((tbp->b_flags & B_MALLOC) ||
 376             ((tbp->b_flags & B_VMIO) == 0) || (run <= 1)) {
 377                 return tbp;
 378         }
 379
 380         bp = trypbuf(&cluster_pbuf_freecnt);
 381         if (bp == NULL) {
 382                 return tbp;
 383         }
 384
 385         /*
 386          * We are synthesizing a buffer out of vm_page_t's, but
 387          * if the block size is not page aligned then the starting
 388          * address may not be either.  Inherit the b_data offset
 389          * from the original buffer.
 390          */
 391         bp->b_data = (char *)((vm_offset_t)bp->b_data |
 392             ((vm_offset_t)tbp->b_data & PAGE_MASK));
 393         bp->b_flags |= B_CLUSTER | B_VMIO;
 394         bp->b_cmd = BUF_CMD_READ;
 395         bp->b_bio1.bio_done = cluster_callback;         /* default to async */
 396         bp->b_bio1.bio_caller_info1.cluster_head = NULL;
 397         bp->b_bio1.bio_caller_info2.cluster_tail = NULL;
 398         bp->b_loffset = loffset;
 399         bp->b_bio2.bio_offset = doffset;
 400         KASSERT(bp->b_loffset != NOOFFSET,
 401                 ("cluster_rbuild: no buffer offset"));
 402
 403         bp->b_bcount = 0;
 404         bp->b_bufsize = 0;
 405         bp->b_xio.xio_npages = 0;
 406
 407         for (boffset = doffset, i = 0; i < run; ++i, boffset += blksize) {
 408                 if (i) {
 409                         if ((bp->b_xio.xio_npages * PAGE_SIZE) +
 410                             round_page(blksize) > maxiosize) {
 411                                 break;
 412                         }
 413
 414                         /*
 415                          * Shortcut some checks and try to avoid buffers that
 416                          * would block in the lock.  The same checks have to
 417                          * be made again after we officially get the buffer.
 418                          */
 419                         tbp = getblk(vp, loffset + i * blksize, blksize,
 420                                      GETBLK_SZMATCH|GETBLK_NOWAIT, 0);
 421                         if (tbp == NULL)
 422                                 break;
 423                         for (j = 0; j < tbp->b_xio.xio_npages; j++) {
 424                                 if (tbp->b_xio.xio_pages[j]->valid)
 425                                         break;
 426                         }
 427                         if (j != tbp->b_xio.xio_npages) {
 428                                 bqrelse(tbp);
 429                                 break;
 430                         }
 431
 432                         /*
 433                          * Stop scanning if the buffer is fuly valid
 434                          * (marked B_CACHE), or locked (may be doing a
 435                          * background write), or if the buffer is not
 436                          * VMIO backed.  The clustering code can only deal
 437                          * with VMIO-backed buffers.
 438                          */
 439                         if ((tbp->b_flags & (B_CACHE|B_LOCKED)) ||
 440                             (tbp->b_flags & B_VMIO) == 0 ||
 441                             (LIST_FIRST(&tbp->b_dep) != NULL &&
 442                              buf_checkread(tbp))
 443                         ) {
 444                                 bqrelse(tbp);
 445                                 break;
 446                         }
 447
 448                         /*
 449                          * The buffer must be completely invalid in order to
 450                          * take part in the cluster.  If it is partially valid
 451                          * then we stop.
 452                          */
 453                         for (j = 0;j < tbp->b_xio.xio_npages; j++) {
 454                                 if (tbp->b_xio.xio_pages[j]->valid)
 455                                         break;
 456                         }
 457                         if (j != tbp->b_xio.xio_npages) {
 458                                 bqrelse(tbp);
 459                                 break;
 460                         }
 461
 462                         /*
 463                          * Set a read-ahead mark as appropriate
 464                          */
 465                         if (i == 1 || i == (run - 1))
 466                                 cluster_setram(tbp);
 467
 468                         /*
 469                          * Depress the priority of buffers not explicitly
 470                          * requested.
 471                          */
 472                         /* tbp->b_flags |= B_AGE; */
 473
 474                         /*
 475                          * Set the block number if it isn't set, otherwise
 476                          * if it is make sure it matches the block number we
 477                          * expect.
 478                          */
 479                         if (tbp->b_bio2.bio_offset == NOOFFSET) {
 480                                 tbp->b_bio2.bio_offset = boffset;
 481                         } else if (tbp->b_bio2.bio_offset != boffset) {
 482                                 brelse(tbp);
 483                                 break;
 484                         }
 485                 }
 486
 487                 /*
 488                  * The passed-in tbp (i == 0) will already be set up for
 489                  * async or sync operation.  All other tbp's acquire in
 490                  * our loop are set up for async operation.
 491                  */
 492                 tbp->b_cmd = BUF_CMD_READ;
 493                 BUF_KERNPROC(tbp);
 494                 cluster_append(&bp->b_bio1, tbp);
 495                 for (j = 0; j < tbp->b_xio.xio_npages; ++j) {
 496                         vm_page_t m;
 497                         m = tbp->b_xio.xio_pages[j];
 498                         vm_page_io_start(m);
 499                         vm_object_pip_add(m->object, 1);
 500                         if ((bp->b_xio.xio_npages == 0) ||
 501                                 (bp->b_xio.xio_pages[bp->b_xio.xio_npages-1] != m)) {
 502                                 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m;
 503                                 bp->b_xio.xio_npages++;
 504                         }
 505                         if ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL)
 506                                 tbp->b_xio.xio_pages[j] = bogus_page;
 507                 }
 508                 /*
 509                  * XXX shouldn't this be += size for both, like in
 510                  * cluster_wbuild()?
 511                  *
 512                  * Don't inherit tbp->b_bufsize as it may be larger due to
 513                  * a non-page-aligned size.  Instead just aggregate using
 514                  * 'size'.
 515                  */
 516                 if (tbp->b_bcount != blksize)
 517                     kprintf("warning: tbp->b_bcount wrong %d vs %d\n", tbp->b_bcount, blksize);
 518                 if (tbp->b_bufsize != blksize)
 519                     kprintf("warning: tbp->b_bufsize wrong %d vs %d\n", tbp->b_bufsize, blksize);
 520                 bp->b_bcount += blksize;
 521                 bp->b_bufsize += blksize;
 522         }
 523
 524         /*
 525          * Fully valid pages in the cluster are already good and do not need
 526          * to be re-read from disk.  Replace the page with bogus_page
 527          */
 528         for (j = 0; j < bp->b_xio.xio_npages; j++) {
 529                 if ((bp->b_xio.xio_pages[j]->valid & VM_PAGE_BITS_ALL) ==
 530                     VM_PAGE_BITS_ALL) {
 531                         bp->b_xio.xio_pages[j] = bogus_page;
 532                 }
 533         }
 534         if (bp->b_bufsize > bp->b_kvasize) {
 535                 panic("cluster_rbuild: b_bufsize(%d) > b_kvasize(%d)",
 536                     bp->b_bufsize, bp->b_kvasize);
 537         }
 538         pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
 539                 (vm_page_t *)bp->b_xio.xio_pages, bp->b_xio.xio_npages);
 540         BUF_KERNPROC(bp);
 541         return (bp);
 542 }
 543
 544 /*
 545  * Cleanup after a clustered read or write.
 546  * This is complicated by the fact that any of the buffers might have
 547  * extra memory (if there were no empty buffer headers at allocbuf time)
 548  * that we will need to shift around.
 549  *
 550  * The returned bio is &bp->b_bio1
 551  */
 552 void
 553 cluster_callback(struct bio *bio)
 554 {
 555         struct buf *bp = bio->bio_buf;
 556         struct buf *tbp;
 557         int error = 0;
 558
 559         /*
 560          * Must propogate errors to all the components.  A short read (EOF)
 561          * is a critical error.
 562          */
 563         if (bp->b_flags & B_ERROR) {
 564                 error = bp->b_error;
 565         } else if (bp->b_bcount != bp->b_bufsize) {
 566                 panic("cluster_callback: unexpected EOF on cluster %p!", bio);
 567         }
 568
 569         pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_xio.xio_npages);
 570         /*
 571          * Move memory from the large cluster buffer into the component
 572          * buffers and mark IO as done on these.  Since the memory map
 573          * is the same, no actual copying is required.
 574          */
 575         while ((tbp = bio->bio_caller_info1.cluster_head) != NULL) {
 576                 bio->bio_caller_info1.cluster_head = tbp->b_cluster_next;
 577                 if (error) {
 578                         tbp->b_flags |= B_ERROR;
 579                         tbp->b_error = error;
 580                 } else {
 581                         tbp->b_dirtyoff = tbp->b_dirtyend = 0;
 582                         tbp->b_flags &= ~(B_ERROR|B_INVAL);
 583                         /*
 584                          * XXX the bdwrite()/bqrelse() issued during
 585                          * cluster building clears B_RELBUF (see bqrelse()
 586                          * comment).  If direct I/O was specified, we have
 587                          * to restore it here to allow the buffer and VM
 588                          * to be freed.
 589                          */
 590                         if (tbp->b_flags & B_DIRECT)
 591                                 tbp->b_flags |= B_RELBUF;
 592                 }
 593                 biodone(&tbp->b_bio1);
 594         }
 595         relpbuf(bp, &cluster_pbuf_freecnt);
 596 }
 597
 598 /*
 599  *      cluster_wbuild_wb:
 600  *
 601  *      Implement modified write build for cluster.
 602  *
 603  *              write_behind = 0        write behind disabled
 604  *              write_behind = 1        write behind normal (default)
 605  *              write_behind = 2        write behind backed-off
 606  */
 607
 608 static __inline int
 609 cluster_wbuild_wb(struct vnode *vp, int blksize, off_t start_loffset, int len)
 610 {
 611         int r = 0;
 612
 613         switch(write_behind) {
 614         case 2:
 615                 if (start_loffset < len)
 616                         break;
 617                 start_loffset -= len;
 618                 /* fall through */
 619         case 1:
 620                 r = cluster_wbuild(vp, blksize, start_loffset, len);
 621                 /* fall through */
 622         default:
 623                 /* fall through */
 624                 break;
 625         }
 626         return(r);
 627 }
 628
 629 /*
 630  * Do clustered write for FFS.
 631  *
 632  * Three cases:
 633  *      1. Write is not sequential (write asynchronously)
 634  *      Write is sequential:
 635  *      2.      beginning of cluster - begin cluster
 636  *      3.      middle of a cluster - add to cluster
 637  *      4.      end of a cluster - asynchronously write cluster
 638  */
 639 void
 640 cluster_write(struct buf *bp, off_t filesize, int blksize, int seqcount)
 641 {
 642         struct vnode *vp;
 643         off_t loffset;
 644         int maxclen, cursize;
 645         int async;
 646
 647         vp = bp->b_vp;
 648         if (vp->v_type == VREG)
 649                 async = vp->v_mount->mnt_flag & MNT_ASYNC;
 650         else
 651                 async = 0;
 652         loffset = bp->b_loffset;
 653         KASSERT(bp->b_loffset != NOOFFSET,
 654                 ("cluster_write: no buffer offset"));
 655
 656         /* Initialize vnode to beginning of file. */
 657         if (loffset == 0)
 658                 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0;
 659
 660         if (vp->v_clen == 0 || loffset != vp->v_lastw + blksize ||
 661             bp->b_bio2.bio_offset == NOOFFSET ||
 662             (bp->b_bio2.bio_offset != vp->v_lasta + blksize)) {
 663                 maxclen = vmaxiosize(vp);
 664                 if (vp->v_clen != 0) {
 665                         /*
 666                          * Next block is not sequential.
 667                          *
 668                          * If we are not writing at end of file, the process
 669                          * seeked to another point in the file since its last
 670                          * write, or we have reached our maximum cluster size,
 671                          * then push the previous cluster. Otherwise try
 672                          * reallocating to make it sequential.
 673                          *
 674                          * Change to algorithm: only push previous cluster if
 675                          * it was sequential from the point of view of the
 676                          * seqcount heuristic, otherwise leave the buffer
 677                          * intact so we can potentially optimize the I/O
 678                          * later on in the buf_daemon or update daemon
 679                          * flush.
 680                          */
 681                         cursize = vp->v_lastw - vp->v_cstart + blksize;
 682                         if (bp->b_loffset + blksize != filesize ||
 683                             loffset != vp->v_lastw + blksize || vp->v_clen <= cursize) {
 684                                 if (!async && seqcount > 0) {
 685                                         cluster_wbuild_wb(vp, blksize,
 686                                                 vp->v_cstart, cursize);
 687                                 }
 688                         } else {
 689                                 struct buf **bpp, **endbp;
 690                                 struct cluster_save *buflist;
 691
 692                                 buflist = cluster_collectbufs(vp, bp, blksize);
 693                                 endbp = &buflist->bs_children
 694                                     [buflist->bs_nchildren - 1];
 695                                 if (VOP_REALLOCBLKS(vp, buflist)) {
 696                                         /*
 697                                          * Failed, push the previous cluster
 698                                          * if *really* writing sequentially
 699                                          * in the logical file (seqcount > 1),
 700                                          * otherwise delay it in the hopes that
 701                                          * the low level disk driver can
 702                                          * optimize the write ordering.
 703                                          */
 704                                         for (bpp = buflist->bs_children;
 705                                              bpp < endbp; bpp++)
 706                                                 brelse(*bpp);
 707                                         kfree(buflist, M_SEGMENT);
 708                                         if (seqcount > 1) {
 709                                                 cluster_wbuild_wb(vp,
 710                                                     blksize, vp->v_cstart,
 711                                                     cursize);
 712                                         }
 713                                 } else {
 714                                         /*
 715                                          * Succeeded, keep building cluster.
 716                                          */
 717                                         for (bpp = buflist->bs_children;
 718                                              bpp <= endbp; bpp++)
 719                                                 bdwrite(*bpp);
 720                                         kfree(buflist, M_SEGMENT);
 721                                         vp->v_lastw = loffset;
 722                                         vp->v_lasta = bp->b_bio2.bio_offset;
 723                                         return;
 724                                 }
 725                         }
 726                 }
 727                 /*
 728                  * Consider beginning a cluster. If at end of file, make
 729                  * cluster as large as possible, otherwise find size of
 730                  * existing cluster.
 731                  */
 732                 if ((vp->v_type == VREG) &&
 733                     bp->b_loffset + blksize != filesize &&
 734                     (bp->b_bio2.bio_offset == NOOFFSET) &&
 735                     (VOP_BMAP(vp, loffset, &bp->b_bio2.bio_offset, &maxclen, NULL, BUF_CMD_WRITE) ||
 736                      bp->b_bio2.bio_offset == NOOFFSET)) {
 737                         bawrite(bp);
 738                         vp->v_clen = 0;
 739                         vp->v_lasta = bp->b_bio2.bio_offset;
 740                         vp->v_cstart = loffset + blksize;
 741                         vp->v_lastw = loffset;
 742                         return;
 743                 }
 744                 if (maxclen > blksize)
 745                         vp->v_clen = maxclen - blksize;
 746                 else
 747                         vp->v_clen = 0;
 748                 if (!async && vp->v_clen == 0) { /* I/O not contiguous */
 749                         vp->v_cstart = loffset + blksize;
 750                         bawrite(bp);
 751                 } else {        /* Wait for rest of cluster */
 752                         vp->v_cstart = loffset;
 753                         bdwrite(bp);
 754                 }
 755         } else if (loffset == vp->v_cstart + vp->v_clen) {
 756                 /*
 757                  * At end of cluster, write it out if seqcount tells us we
 758                  * are operating sequentially, otherwise let the buf or
 759                  * update daemon handle it.
 760                  */
 761                 bdwrite(bp);
 762                 if (seqcount > 1)
 763                         cluster_wbuild_wb(vp, blksize, vp->v_cstart,
 764                                           vp->v_clen + blksize);
 765                 vp->v_clen = 0;
 766                 vp->v_cstart = loffset + blksize;
 767         } else if (vm_page_count_severe()) {
 768                 /*
 769                  * We are low on memory, get it going NOW
 770                  */
 771                 bawrite(bp);
 772         } else {
 773                 /*
 774                  * In the middle of a cluster, so just delay the I/O for now.
 775                  */
 776                 bdwrite(bp);
 777         }
 778         vp->v_lastw = loffset;
 779         vp->v_lasta = bp->b_bio2.bio_offset;
 780 }
 781
 782
 783 /*
 784  * This is an awful lot like cluster_rbuild...wish they could be combined.
 785  * The last lbn argument is the current block on which I/O is being
 786  * performed.  Check to see that it doesn't fall in the middle of
 787  * the current block (if last_bp == NULL).
 788  */
 789 int
 790 cluster_wbuild(struct vnode *vp, int blksize, off_t start_loffset, int bytes)
 791 {
 792         struct buf *bp, *tbp;
 793         int i, j;
 794         int totalwritten = 0;
 795         int maxiosize = vmaxiosize(vp);
 796
 797         while (bytes > 0) {
 798                 /*
 799                  * If the buffer is not delayed-write (i.e. dirty), or it
 800                  * is delayed-write but either locked or inval, it cannot
 801                  * partake in the clustered write.
 802                  */
 803                 tbp = findblk(vp, start_loffset, FINDBLK_NBLOCK);
 804                 if (tbp == NULL ||
 805                     (tbp->b_flags & (B_LOCKED | B_INVAL | B_DELWRI)) != B_DELWRI ||
 806                     (LIST_FIRST(&tbp->b_dep) && buf_checkwrite(tbp))) {
 807                         if (tbp)
 808                                 BUF_UNLOCK(tbp);
 809                         start_loffset += blksize;
 810                         bytes -= blksize;
 811                         continue;
 812                 }
 813                 bremfree(tbp);
 814                 KKASSERT(tbp->b_cmd == BUF_CMD_DONE);
 815
 816                 /*
 817                  * Extra memory in the buffer, punt on this buffer.
 818                  * XXX we could handle this in most cases, but we would
 819                  * have to push the extra memory down to after our max
 820                  * possible cluster size and then potentially pull it back
 821                  * up if the cluster was terminated prematurely--too much
 822                  * hassle.
 823                  */
 824                 if (((tbp->b_flags & (B_CLUSTEROK|B_MALLOC)) != B_CLUSTEROK) ||
 825                     (tbp->b_bcount != tbp->b_bufsize) ||
 826                     (tbp->b_bcount != blksize) ||
 827                     (bytes == blksize) ||
 828                     ((bp = getpbuf(&cluster_pbuf_freecnt)) == NULL)) {
 829                         totalwritten += tbp->b_bufsize;
 830                         bawrite(tbp);
 831                         start_loffset += blksize;
 832                         bytes -= blksize;
 833                         continue;
 834                 }
 835
 836                 /*
 837                  * Set up the pbuf.  Track our append point with b_bcount
 838                  * and b_bufsize.  b_bufsize is not used by the device but
 839                  * our caller uses it to loop clusters and we use it to
 840                  * detect a premature EOF on the block device.
 841                  */
 842                 bp->b_bcount = 0;
 843                 bp->b_bufsize = 0;
 844                 bp->b_xio.xio_npages = 0;
 845                 bp->b_loffset = tbp->b_loffset;
 846                 bp->b_bio2.bio_offset = tbp->b_bio2.bio_offset;
 847
 848                 /*
 849                  * We are synthesizing a buffer out of vm_page_t's, but
 850                  * if the block size is not page aligned then the starting
 851                  * address may not be either.  Inherit the b_data offset
 852                  * from the original buffer.
 853                  */
 854                 bp->b_data = (char *)((vm_offset_t)bp->b_data |
 855                     ((vm_offset_t)tbp->b_data & PAGE_MASK));
 856                 bp->b_flags &= ~B_ERROR;
 857                 bp->b_flags |= B_CLUSTER | B_BNOCLIP |
 858                         (tbp->b_flags & (B_VMIO | B_NEEDCOMMIT));
 859                 bp->b_bio1.bio_caller_info1.cluster_head = NULL;
 860                 bp->b_bio1.bio_caller_info2.cluster_tail = NULL;
 861
 862                 /*
 863                  * From this location in the file, scan forward to see
 864                  * if there are buffers with adjacent data that need to
 865                  * be written as well.
 866                  */
 867                 for (i = 0; i < bytes; (i += blksize), (start_loffset += blksize)) {
 868                         if (i != 0) { /* If not the first buffer */
 869                                 tbp = findblk(vp, start_loffset,
 870                                               FINDBLK_NBLOCK);
 871                                 /*
 872                                  * Buffer not found or could not be locked
 873                                  * non-blocking.
 874                                  */
 875                                 if (tbp == NULL)
 876                                         break;
 877
 878                                 /*
 879                                  * If it IS in core, but has different
 880                                  * characteristics, then don't cluster
 881                                  * with it.
 882                                  */
 883                                 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK |
 884                                      B_INVAL | B_DELWRI | B_NEEDCOMMIT))
 885                                     != (B_DELWRI | B_CLUSTEROK |
 886                                      (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) ||
 887                                     (tbp->b_flags & B_LOCKED) ||
 888                                     (LIST_FIRST(&tbp->b_dep) &&
 889                                      buf_checkwrite(tbp))
 890                                 ) {
 891                                         BUF_UNLOCK(tbp);
 892                                         break;
 893                                 }
 894
 895                                 /*
 896                                  * Check that the combined cluster
 897                                  * would make sense with regard to pages
 898                                  * and would not be too large
 899                                  */
 900                                 if ((tbp->b_bcount != blksize) ||
 901                                   ((bp->b_bio2.bio_offset + i) !=
 902                                     tbp->b_bio2.bio_offset) ||
 903                                   ((tbp->b_xio.xio_npages + bp->b_xio.xio_npages) >
 904                                     (maxiosize / PAGE_SIZE))) {
 905                                         BUF_UNLOCK(tbp);
 906                                         break;
 907                                 }
 908                                 /*
 909                                  * Ok, it's passed all the tests,
 910                                  * so remove it from the free list
 911                                  * and mark it busy. We will use it.
 912                                  */
 913                                 bremfree(tbp);
 914                                 KKASSERT(tbp->b_cmd == BUF_CMD_DONE);
 915                         } /* end of code for non-first buffers only */
 916
 917                         /*
 918                          * If the IO is via the VM then we do some
 919                          * special VM hackery (yuck).  Since the buffer's
 920                          * block size may not be page-aligned it is possible
 921                          * for a page to be shared between two buffers.  We
 922                          * have to get rid of the duplication when building
 923                          * the cluster.
 924                          */
 925                         if (tbp->b_flags & B_VMIO) {
 926                                 vm_page_t m;
 927
 928                                 if (i != 0) { /* if not first buffer */
 929                                         for (j = 0; j < tbp->b_xio.xio_npages; ++j) {
 930                                                 m = tbp->b_xio.xio_pages[j];
 931                                                 if (m->flags & PG_BUSY) {
 932                                                         bqrelse(tbp);
 933                                                         goto finishcluster;
 934                                                 }
 935                                         }
 936                                 }
 937
 938                                 for (j = 0; j < tbp->b_xio.xio_npages; ++j) {
 939                                         m = tbp->b_xio.xio_pages[j];
 940                                         vm_page_io_start(m);
 941                                         vm_object_pip_add(m->object, 1);
 942                                         if ((bp->b_xio.xio_npages == 0) ||
 943                                           (bp->b_xio.xio_pages[bp->b_xio.xio_npages - 1] != m)) {
 944                                                 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m;
 945                                                 bp->b_xio.xio_npages++;
 946                                         }
 947                                 }
 948                         }
 949                         bp->b_bcount += blksize;
 950                         bp->b_bufsize += blksize;
 951
 952                         bundirty(tbp);
 953                         tbp->b_flags &= ~B_ERROR;
 954                         tbp->b_cmd = BUF_CMD_WRITE;
 955                         BUF_KERNPROC(tbp);
 956                         cluster_append(&bp->b_bio1, tbp);
 957
 958                         /*
 959                          * check for latent dependencies to be handled
 960                          */
 961                         if (LIST_FIRST(&tbp->b_dep) != NULL)
 962                                 buf_start(tbp);
 963                 }
 964         finishcluster:
 965                 pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
 966                         (vm_page_t *) bp->b_xio.xio_pages, bp->b_xio.xio_npages);
 967                 if (bp->b_bufsize > bp->b_kvasize) {
 968                         panic(
 969                             "cluster_wbuild: b_bufsize(%d) > b_kvasize(%d)\n",
 970                             bp->b_bufsize, bp->b_kvasize);
 971                 }
 972                 totalwritten += bp->b_bufsize;
 973                 bp->b_dirtyoff = 0;
 974                 bp->b_dirtyend = bp->b_bufsize;
 975                 bp->b_bio1.bio_done = cluster_callback;
 976                 bp->b_cmd = BUF_CMD_WRITE;
 977
 978                 vfs_busy_pages(vp, bp);
 979                 bp->b_runningbufspace = bp->b_bufsize;
 980                 if (bp->b_runningbufspace) {
 981                         runningbufspace += bp->b_runningbufspace;
 982                         ++runningbufcount;
 983                 }
 984                 BUF_KERNPROC(bp);
 985                 vn_strategy(vp, &bp->b_bio1);
 986
 987                 bytes -= i;
 988         }
 989         return totalwritten;
 990 }
 991
 992 /*
 993  * Collect together all the buffers in a cluster.
 994  * Plus add one additional buffer.
 995  */
 996 static struct cluster_save *
 997 cluster_collectbufs(struct vnode *vp, struct buf *last_bp, int blksize)
 998 {
 999         struct cluster_save *buflist;
1000         struct buf *bp;
1001         off_t loffset;
1002         int i, len;
1003
1004         len = (int)(vp->v_lastw - vp->v_cstart + blksize) / blksize;
1005         buflist = kmalloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist),
1006                          M_SEGMENT, M_WAITOK);
1007         buflist->bs_nchildren = 0;
1008         buflist->bs_children = (struct buf **) (buflist + 1);
1009         for (loffset = vp->v_cstart, i = 0; i < len; (loffset += blksize), i++) {
1010                 (void) bread(vp, loffset, last_bp->b_bcount, &bp);
1011                 buflist->bs_children[i] = bp;
1012                 if (bp->b_bio2.bio_offset == NOOFFSET) {
1013                         VOP_BMAP(bp->b_vp, bp->b_loffset,
1014                                  &bp->b_bio2.bio_offset,
1015                                  NULL, NULL, BUF_CMD_WRITE);
1016                 }
1017         }
1018         buflist->bs_children[i] = bp = last_bp;
1019         if (bp->b_bio2.bio_offset == NOOFFSET) {
1020                 VOP_BMAP(bp->b_vp, bp->b_loffset, &bp->b_bio2.bio_offset,
1021                          NULL, NULL, BUF_CMD_WRITE);
1022         }
1023         buflist->bs_nchildren = i + 1;
1024         return (buflist);
1025 }
1026
1027 void
1028 cluster_append(struct bio *bio, struct buf *tbp)
1029 {
1030         tbp->b_cluster_next = NULL;
1031         if (bio->bio_caller_info1.cluster_head == NULL) {
1032                 bio->bio_caller_info1.cluster_head = tbp;
1033                 bio->bio_caller_info2.cluster_tail = tbp;
1034         } else {
1035                 bio->bio_caller_info2.cluster_tail->b_cluster_next = tbp;
1036                 bio->bio_caller_info2.cluster_tail = tbp;
1037         }
1038 }
1039
1040 static
1041 void
1042 cluster_setram (struct buf *bp)
1043 {
1044         bp->b_flags |= B_RAM;
1045         if (bp->b_xio.xio_npages)
1046                 vm_page_flag_set(bp->b_xio.xio_pages[0], PG_RAM);
1047 }