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
  57 #include <sys/buf2.h>
  58 #include <vm/vm_page2.h>
  59
  60 #include <machine/limits.h>
  61
  62 #if defined(CLUSTERDEBUG)
  63 #include <sys/sysctl.h>
  64 static int      rcluster= 0;
  65 SYSCTL_INT(_debug, OID_AUTO, rcluster, CTLFLAG_RW, &rcluster, 0, "");
  66 #endif
  67
  68 static MALLOC_DEFINE(M_SEGMENT, "cluster_save", "cluster_save buffer");
  69
  70 static struct cluster_save *
  71         cluster_collectbufs (struct vnode *vp, struct buf *last_bp,
  72                             int blksize);
  73 static struct buf *
  74         cluster_rbuild (struct vnode *vp, off_t filesize, off_t loffset,
  75                             off_t doffset, int blksize, int run,
  76                             struct buf *fbp);
  77 static void cluster_callback (struct bio *);
  78 static void cluster_setram (struct buf *);
  79 static int cluster_wbuild(struct vnode *vp, struct buf **bpp, int blksize,
  80                             off_t start_loffset, int bytes);
  81
  82 static int write_behind = 1;
  83 SYSCTL_INT(_vfs, OID_AUTO, write_behind, CTLFLAG_RW, &write_behind, 0,
  84     "Cluster write-behind setting");
  85 static quad_t write_behind_minfilesize = 10 * 1024 * 1024;
  86 SYSCTL_QUAD(_vfs, OID_AUTO, write_behind_minfilesize, CTLFLAG_RW,
  87     &write_behind_minfilesize, 0, "Cluster write-behind setting");
  88 static int max_readahead = 2 * 1024 * 1024;
  89 SYSCTL_INT(_vfs, OID_AUTO, max_readahead, CTLFLAG_RW, &max_readahead, 0,
  90     "Limit in bytes for desired cluster read-ahead");
  91
  92 extern vm_page_t        bogus_page;
  93
  94 extern int cluster_pbuf_freecnt;
  95
  96 /*
  97  * This replaces bread.
  98  *
  99  * filesize     - read-ahead @ blksize will not cross this boundary
 100  * loffset      - loffset for returned *bpp
 101  * blksize      - blocksize for returned *bpp and read-ahead bps
 102  * minreq       - minimum (not a hard minimum) in bytes, typically reflects
 103  *                a higher level uio resid.
 104  * maxreq       - maximum (sequential heuristic) in bytes (highet typ ~2MB)
 105  * bpp          - return buffer (*bpp) for (loffset,blksize)
 106  */
 107 int
 108 cluster_readx(struct vnode *vp, off_t filesize, off_t loffset,
 109              int blksize, size_t minreq, size_t maxreq, struct buf **bpp)
 110 {
 111         struct buf *bp, *rbp, *reqbp;
 112         off_t origoffset;
 113         off_t doffset;
 114         int error;
 115         int i;
 116         int maxra;
 117         int maxrbuild;
 118
 119         error = 0;
 120
 121         /*
 122          * Calculate the desired read-ahead in blksize'd blocks (maxra).
 123          * To do this we calculate maxreq.
 124          *
 125          * maxreq typically starts out as a sequential heuristic.  If the
 126          * high level uio/resid is bigger (minreq), we pop maxreq up to
 127          * minreq.  This represents the case where random I/O is being
 128          * performed by the userland is issuing big read()'s.
 129          *
 130          * Then we limit maxreq to max_readahead to ensure it is a reasonable
 131          * value.
 132          *
 133          * Finally we must ensure that (loffset + maxreq) does not cross the
 134          * boundary (filesize) for the current blocksize.  If we allowed it
 135          * to cross we could end up with buffers past the boundary with the
 136          * wrong block size (HAMMER large-data areas use mixed block sizes).
 137          * minreq is also absolutely limited to filesize.
 138          */
 139         if (maxreq < minreq)
 140                 maxreq = minreq;
 141         /* minreq not used beyond this point */
 142
 143         if (maxreq > max_readahead) {
 144                 maxreq = max_readahead;
 145                 if (maxreq > 16 * 1024 * 1024)
 146                         maxreq = 16 * 1024 * 1024;
 147         }
 148         if (maxreq < blksize)
 149                 maxreq = blksize;
 150         if (loffset + maxreq > filesize) {
 151                 if (loffset > filesize)
 152                         maxreq = 0;
 153                 else
 154                         maxreq = filesize - loffset;
 155         }
 156
 157         maxra = (int)(maxreq / blksize);
 158
 159         /*
 160          * Get the requested block.
 161          */
 162         if (*bpp)
 163                 reqbp = bp = *bpp;
 164         else
 165                 *bpp = reqbp = bp = getblk(vp, loffset, blksize, 0, 0);
 166         origoffset = loffset;
 167
 168         /*
 169          * Calculate the maximum cluster size for a single I/O, used
 170          * by cluster_rbuild().
 171          */
 172         maxrbuild = vmaxiosize(vp) / blksize;
 173
 174         /*
 175          * if it is in the cache, then check to see if the reads have been
 176          * sequential.  If they have, then try some read-ahead, otherwise
 177          * back-off on prospective read-aheads.
 178          */
 179         if (bp->b_flags & B_CACHE) {
 180                 /*
 181                  * Not sequential, do not do any read-ahead
 182                  */
 183                 if (maxra <= 1)
 184                         return 0;
 185
 186                 /*
 187                  * No read-ahead mark, do not do any read-ahead
 188                  * yet.
 189                  */
 190                 if ((bp->b_flags & B_RAM) == 0)
 191                         return 0;
 192
 193                 /*
 194                  * We hit a read-ahead-mark, figure out how much read-ahead
 195                  * to do (maxra) and where to start (loffset).
 196                  *
 197                  * Shortcut the scan.  Typically the way this works is that
 198                  * we've built up all the blocks inbetween except for the
 199                  * last in previous iterations, so if the second-to-last
 200                  * block is present we just skip ahead to it.
 201                  *
 202                  * This algorithm has O(1) cpu in the steady state no
 203                  * matter how large maxra is.
 204                  */
 205                 bp->b_flags &= ~B_RAM;
 206
 207                 if (findblk(vp, loffset + (maxra - 2) * blksize, FINDBLK_TEST))
 208                         i = maxra - 1;
 209                 else
 210                         i = 1;
 211                 while (i < maxra) {
 212                         if (findblk(vp, loffset + i * blksize,
 213                                     FINDBLK_TEST) == NULL) {
 214                                 break;
 215                         }
 216                         ++i;
 217                 }
 218
 219                 /*
 220                  * We got everything or everything is in the cache, no
 221                  * point continuing.
 222                  */
 223                 if (i >= maxra)
 224                         return 0;
 225
 226                 /*
 227                  * Calculate where to start the read-ahead and how much
 228                  * to do.  Generally speaking we want to read-ahead by
 229                  * (maxra) when we've found a read-ahead mark.  We do
 230                  * not want to reduce maxra here as it will cause
 231                  * successive read-ahead I/O's to be smaller and smaller.
 232                  *
 233                  * However, we have to make sure we don't break the
 234                  * filesize limitation for the clustered operation.
 235                  */
 236                 loffset += i * blksize;
 237                 reqbp = bp = NULL;
 238
 239                 if (loffset >= filesize)
 240                         return 0;
 241                 if (loffset + maxra * blksize > filesize) {
 242                         maxreq = filesize - loffset;
 243                         maxra = (int)(maxreq / blksize);
 244                 }
 245         } else {
 246                 __debugvar off_t firstread = bp->b_loffset;
 247                 int nblks;
 248
 249                 /*
 250                  * Set-up synchronous read for bp.
 251                  */
 252                 bp->b_cmd = BUF_CMD_READ;
 253                 bp->b_bio1.bio_done = biodone_sync;
 254                 bp->b_bio1.bio_flags |= BIO_SYNC;
 255
 256                 KASSERT(firstread != NOOFFSET,
 257                         ("cluster_read: no buffer offset"));
 258
 259                 /*
 260                  * nblks is our cluster_rbuild request size, limited
 261                  * primarily by the device.
 262                  */
 263                 if ((nblks = maxra) > maxrbuild)
 264                         nblks = maxrbuild;
 265
 266                 if (nblks > 1) {
 267                         int burstbytes;
 268
 269                         error = VOP_BMAP(vp, loffset, &doffset,
 270                                          &burstbytes, NULL, BUF_CMD_READ);
 271                         if (error)
 272                                 goto single_block_read;
 273                         if (nblks > burstbytes / blksize)
 274                                 nblks = burstbytes / blksize;
 275                         if (doffset == NOOFFSET)
 276                                 goto single_block_read;
 277                         if (nblks <= 1)
 278                                 goto single_block_read;
 279
 280                         bp = cluster_rbuild(vp, filesize, loffset,
 281                                             doffset, blksize, nblks, bp);
 282                         loffset += bp->b_bufsize;
 283                         maxra -= bp->b_bufsize / blksize;
 284                 } else {
 285 single_block_read:
 286                         /*
 287                          * If it isn't in the cache, then get a chunk from
 288                          * disk if sequential, otherwise just get the block.
 289                          */
 290                         cluster_setram(bp);
 291                         loffset += blksize;
 292                         --maxra;
 293                 }
 294         }
 295
 296         /*
 297          * If B_CACHE was not set issue bp.  bp will either be an
 298          * asynchronous cluster buf or a synchronous single-buf.
 299          * If it is a single buf it will be the same as reqbp.
 300          *
 301          * NOTE: Once an async cluster buf is issued bp becomes invalid.
 302          */
 303         if (bp) {
 304 #if defined(CLUSTERDEBUG)
 305                 if (rcluster)
 306                         kprintf("S(%012jx,%d,%d)\n",
 307                             (intmax_t)bp->b_loffset, bp->b_bcount, maxra);
 308 #endif
 309                 if ((bp->b_flags & B_CLUSTER) == 0)
 310                         vfs_busy_pages(vp, bp);
 311                 bp->b_flags &= ~(B_ERROR|B_INVAL);
 312                 vn_strategy(vp, &bp->b_bio1);
 313                 error = 0;
 314                 /* bp invalid now */
 315         }
 316
 317         /*
 318          * If we have been doing sequential I/O, then do some read-ahead.
 319          * The code above us should have positioned us at the next likely
 320          * offset.
 321          *
 322          * Only mess with buffers which we can immediately lock.  HAMMER
 323          * will do device-readahead irrespective of what the blocks
 324          * represent.
 325          */
 326         while (error == 0 && maxra > 0) {
 327                 int burstbytes;
 328                 int tmp_error;
 329                 int nblks;
 330
 331                 rbp = getblk(vp, loffset, blksize,
 332                              GETBLK_SZMATCH|GETBLK_NOWAIT, 0);
 333                 if (rbp == NULL)
 334                         goto no_read_ahead;
 335                 if ((rbp->b_flags & B_CACHE)) {
 336                         bqrelse(rbp);
 337                         goto no_read_ahead;
 338                 }
 339
 340                 /*
 341                  * An error from the read-ahead bmap has nothing to do
 342                  * with the caller's original request.
 343                  */
 344                 tmp_error = VOP_BMAP(vp, loffset, &doffset,
 345                                      &burstbytes, NULL, BUF_CMD_READ);
 346                 if (tmp_error || doffset == NOOFFSET) {
 347                         rbp->b_flags |= B_INVAL;
 348                         brelse(rbp);
 349                         rbp = NULL;
 350                         goto no_read_ahead;
 351                 }
 352                 if ((nblks = maxra) > maxrbuild)
 353                         nblks = maxrbuild;
 354                 if (nblks > burstbytes / blksize)
 355                         nblks = burstbytes / blksize;
 356
 357                 /*
 358                  * rbp: async read
 359                  */
 360                 rbp->b_cmd = BUF_CMD_READ;
 361                 /*rbp->b_flags |= B_AGE*/;
 362                 cluster_setram(rbp);
 363
 364                 if (nblks > 1) {
 365                         rbp = cluster_rbuild(vp, filesize, loffset,
 366                                              doffset, blksize,
 367                                              nblks, rbp);
 368                 } else {
 369                         rbp->b_bio2.bio_offset = doffset;
 370                 }
 371
 372 #if defined(CLUSTERDEBUG)
 373                 if (rcluster) {
 374                         if (bp) {
 375                                 kprintf("A+(%012jx,%d,%jd) "
 376                                         "doff=%012jx minr=%zd ra=%d\n",
 377                                     (intmax_t)loffset, rbp->b_bcount,
 378                                     (intmax_t)(loffset - origoffset),
 379                                     (intmax_t)doffset, minreq, maxra);
 380                         } else {
 381                                 kprintf("A-(%012jx,%d,%jd) "
 382                                         "doff=%012jx minr=%zd ra=%d\n",
 383                                     (intmax_t)rbp->b_loffset, rbp->b_bcount,
 384                                     (intmax_t)(loffset - origoffset),
 385                                     (intmax_t)doffset, minreq, maxra);
 386                         }
 387                 }
 388 #endif
 389                 rbp->b_flags &= ~(B_ERROR|B_INVAL);
 390
 391                 if ((rbp->b_flags & B_CLUSTER) == 0)
 392                         vfs_busy_pages(vp, rbp);
 393                 BUF_KERNPROC(rbp);
 394                 loffset += rbp->b_bufsize;
 395                 maxra -= rbp->b_bufsize / blksize;
 396                 vn_strategy(vp, &rbp->b_bio1);
 397                 /* rbp invalid now */
 398         }
 399
 400         /*
 401          * Wait for our original buffer to complete its I/O.  reqbp will
 402          * be NULL if the original buffer was B_CACHE.  We are returning
 403          * (*bpp) which is the same as reqbp when reqbp != NULL.
 404          */
 405 no_read_ahead:
 406         if (reqbp) {
 407                 KKASSERT(reqbp->b_bio1.bio_flags & BIO_SYNC);
 408                 error = biowait(&reqbp->b_bio1, "clurd");
 409         }
 410         return (error);
 411 }
 412
 413 /*
 414  * If blocks are contiguous on disk, use this to provide clustered
 415  * read ahead.  We will read as many blocks as possible sequentially
 416  * and then parcel them up into logical blocks in the buffer hash table.
 417  *
 418  * This function either returns a cluster buf or it returns fbp.  fbp is
 419  * already expected to be set up as a synchronous or asynchronous request.
 420  *
 421  * If a cluster buf is returned it will always be async.
 422  */
 423 static struct buf *
 424 cluster_rbuild(struct vnode *vp, off_t filesize, off_t loffset, off_t doffset,
 425                int blksize, int run, struct buf *fbp)
 426 {
 427         struct buf *bp, *tbp;
 428         off_t boffset;
 429         int i, j;
 430         int maxiosize = vmaxiosize(vp);
 431
 432         /*
 433          * avoid a division
 434          */
 435         while (loffset + run * blksize > filesize) {
 436                 --run;
 437         }
 438
 439         tbp = fbp;
 440         tbp->b_bio2.bio_offset = doffset;
 441         if((tbp->b_flags & B_MALLOC) ||
 442             ((tbp->b_flags & B_VMIO) == 0) || (run <= 1)) {
 443                 return tbp;
 444         }
 445
 446         bp = trypbuf_kva(&cluster_pbuf_freecnt);
 447         if (bp == NULL) {
 448                 return tbp;
 449         }
 450
 451         /*
 452          * We are synthesizing a buffer out of vm_page_t's, but
 453          * if the block size is not page aligned then the starting
 454          * address may not be either.  Inherit the b_data offset
 455          * from the original buffer.
 456          */
 457         bp->b_data = (char *)((vm_offset_t)bp->b_data |
 458             ((vm_offset_t)tbp->b_data & PAGE_MASK));
 459         bp->b_flags |= B_CLUSTER | B_VMIO;
 460         bp->b_cmd = BUF_CMD_READ;
 461         bp->b_bio1.bio_done = cluster_callback;         /* default to async */
 462         bp->b_bio1.bio_caller_info1.cluster_head = NULL;
 463         bp->b_bio1.bio_caller_info2.cluster_tail = NULL;
 464         bp->b_loffset = loffset;
 465         bp->b_bio2.bio_offset = doffset;
 466         KASSERT(bp->b_loffset != NOOFFSET,
 467                 ("cluster_rbuild: no buffer offset"));
 468
 469         bp->b_bcount = 0;
 470         bp->b_bufsize = 0;
 471         bp->b_xio.xio_npages = 0;
 472
 473         for (boffset = doffset, i = 0; i < run; ++i, boffset += blksize) {
 474                 if (i) {
 475                         if ((bp->b_xio.xio_npages * PAGE_SIZE) +
 476                             round_page(blksize) > maxiosize) {
 477                                 break;
 478                         }
 479
 480                         /*
 481                          * Shortcut some checks and try to avoid buffers that
 482                          * would block in the lock.  The same checks have to
 483                          * be made again after we officially get the buffer.
 484                          */
 485                         tbp = getblk(vp, loffset + i * blksize, blksize,
 486                                      GETBLK_SZMATCH|GETBLK_NOWAIT, 0);
 487                         if (tbp == NULL)
 488                                 break;
 489                         for (j = 0; j < tbp->b_xio.xio_npages; j++) {
 490                                 if (tbp->b_xio.xio_pages[j]->valid)
 491                                         break;
 492                         }
 493                         if (j != tbp->b_xio.xio_npages) {
 494                                 bqrelse(tbp);
 495                                 break;
 496                         }
 497
 498                         /*
 499                          * Stop scanning if the buffer is fuly valid
 500                          * (marked B_CACHE), or locked (may be doing a
 501                          * background write), or if the buffer is not
 502                          * VMIO backed.  The clustering code can only deal
 503                          * with VMIO-backed buffers.
 504                          */
 505                         if ((tbp->b_flags & (B_CACHE|B_LOCKED)) ||
 506                             (tbp->b_flags & B_VMIO) == 0 ||
 507                             (LIST_FIRST(&tbp->b_dep) != NULL &&
 508                              buf_checkread(tbp))
 509                         ) {
 510                                 bqrelse(tbp);
 511                                 break;
 512                         }
 513
 514                         /*
 515                          * The buffer must be completely invalid in order to
 516                          * take part in the cluster.  If it is partially valid
 517                          * then we stop.
 518                          */
 519                         for (j = 0;j < tbp->b_xio.xio_npages; j++) {
 520                                 if (tbp->b_xio.xio_pages[j]->valid)
 521                                         break;
 522                         }
 523                         if (j != tbp->b_xio.xio_npages) {
 524                                 bqrelse(tbp);
 525                                 break;
 526                         }
 527
 528                         /*
 529                          * Set a read-ahead mark as appropriate.  Always
 530                          * set the read-ahead mark at (run - 1).  It is
 531                          * unclear why we were also setting it at i == 1.
 532                          */
 533                         if (/*i == 1 ||*/ i == (run - 1))
 534                                 cluster_setram(tbp);
 535
 536                         /*
 537                          * Depress the priority of buffers not explicitly
 538                          * requested.
 539                          */
 540                         /* tbp->b_flags |= B_AGE; */
 541
 542                         /*
 543                          * Set the block number if it isn't set, otherwise
 544                          * if it is make sure it matches the block number we
 545                          * expect.
 546                          */
 547                         if (tbp->b_bio2.bio_offset == NOOFFSET) {
 548                                 tbp->b_bio2.bio_offset = boffset;
 549                         } else if (tbp->b_bio2.bio_offset != boffset) {
 550                                 brelse(tbp);
 551                                 break;
 552                         }
 553                 }
 554
 555                 /*
 556                  * The passed-in tbp (i == 0) will already be set up for
 557                  * async or sync operation.  All other tbp's acquire in
 558                  * our loop are set up for async operation.
 559                  */
 560                 tbp->b_cmd = BUF_CMD_READ;
 561                 BUF_KERNPROC(tbp);
 562                 cluster_append(&bp->b_bio1, tbp);
 563                 for (j = 0; j < tbp->b_xio.xio_npages; ++j) {
 564                         vm_page_t m;
 565
 566                         m = tbp->b_xio.xio_pages[j];
 567                         vm_page_busy_wait(m, FALSE, "clurpg");
 568                         vm_page_io_start(m);
 569                         vm_page_wakeup(m);
 570                         vm_object_pip_add(m->object, 1);
 571                         if ((bp->b_xio.xio_npages == 0) ||
 572                                 (bp->b_xio.xio_pages[bp->b_xio.xio_npages-1] != m)) {
 573                                 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m;
 574                                 bp->b_xio.xio_npages++;
 575                         }
 576                         if ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL)
 577                                 tbp->b_xio.xio_pages[j] = bogus_page;
 578                 }
 579                 /*
 580                  * XXX shouldn't this be += size for both, like in
 581                  * cluster_wbuild()?
 582                  *
 583                  * Don't inherit tbp->b_bufsize as it may be larger due to
 584                  * a non-page-aligned size.  Instead just aggregate using
 585                  * 'size'.
 586                  */
 587                 if (tbp->b_bcount != blksize)
 588                     kprintf("warning: tbp->b_bcount wrong %d vs %d\n", tbp->b_bcount, blksize);
 589                 if (tbp->b_bufsize != blksize)
 590                     kprintf("warning: tbp->b_bufsize wrong %d vs %d\n", tbp->b_bufsize, blksize);
 591                 bp->b_bcount += blksize;
 592                 bp->b_bufsize += blksize;
 593         }
 594
 595         /*
 596          * Fully valid pages in the cluster are already good and do not need
 597          * to be re-read from disk.  Replace the page with bogus_page
 598          */
 599         for (j = 0; j < bp->b_xio.xio_npages; j++) {
 600                 if ((bp->b_xio.xio_pages[j]->valid & VM_PAGE_BITS_ALL) ==
 601                     VM_PAGE_BITS_ALL) {
 602                         bp->b_xio.xio_pages[j] = bogus_page;
 603                 }
 604         }
 605         if (bp->b_bufsize > bp->b_kvasize) {
 606                 panic("cluster_rbuild: b_bufsize(%d) > b_kvasize(%d)",
 607                     bp->b_bufsize, bp->b_kvasize);
 608         }
 609         pmap_qenter(trunc_page((vm_offset_t) bp->b_data),
 610                 (vm_page_t *)bp->b_xio.xio_pages, bp->b_xio.xio_npages);
 611         BUF_KERNPROC(bp);
 612         return (bp);
 613 }
 614
 615 /*
 616  * Cleanup after a clustered read or write.
 617  * This is complicated by the fact that any of the buffers might have
 618  * extra memory (if there were no empty buffer headers at allocbuf time)
 619  * that we will need to shift around.
 620  *
 621  * The returned bio is &bp->b_bio1
 622  */
 623 void
 624 cluster_callback(struct bio *bio)
 625 {
 626         struct buf *bp = bio->bio_buf;
 627         struct buf *tbp;
 628         int error = 0;
 629
 630         /*
 631          * Must propogate errors to all the components.  A short read (EOF)
 632          * is a critical error.
 633          */
 634         if (bp->b_flags & B_ERROR) {
 635                 error = bp->b_error;
 636         } else if (bp->b_bcount != bp->b_bufsize) {
 637                 panic("cluster_callback: unexpected EOF on cluster %p!", bio);
 638         }
 639
 640         pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_xio.xio_npages);
 641         /*
 642          * Move memory from the large cluster buffer into the component
 643          * buffers and mark IO as done on these.  Since the memory map
 644          * is the same, no actual copying is required.
 645          */
 646         while ((tbp = bio->bio_caller_info1.cluster_head) != NULL) {
 647                 bio->bio_caller_info1.cluster_head = tbp->b_cluster_next;
 648                 if (error) {
 649                         tbp->b_flags |= B_ERROR | B_IODEBUG;
 650                         tbp->b_error = error;
 651                 } else {
 652                         tbp->b_dirtyoff = tbp->b_dirtyend = 0;
 653                         tbp->b_flags &= ~(B_ERROR|B_INVAL);
 654                         tbp->b_flags |= B_IODEBUG;
 655                         /*
 656                          * XXX the bdwrite()/bqrelse() issued during
 657                          * cluster building clears B_RELBUF (see bqrelse()
 658                          * comment).  If direct I/O was specified, we have
 659                          * to restore it here to allow the buffer and VM
 660                          * to be freed.
 661                          */
 662                         if (tbp->b_flags & B_DIRECT)
 663                                 tbp->b_flags |= B_RELBUF;
 664                 }
 665                 biodone(&tbp->b_bio1);
 666         }
 667         relpbuf(bp, &cluster_pbuf_freecnt);
 668 }
 669
 670 /*
 671  * Implement modified write build for cluster.
 672  *
 673  *      write_behind = 0        write behind disabled
 674  *      write_behind = 1        write behind normal (default)
 675  *      write_behind = 2        write behind backed-off
 676  *
 677  * In addition, write_behind is only activated for files that have
 678  * grown past a certain size (default 10MB).  Otherwise temporary files
 679  * wind up generating a lot of unnecessary disk I/O.
 680  */
 681 static __inline int
 682 cluster_wbuild_wb(struct vnode *vp, int blksize, off_t start_loffset, int len)
 683 {
 684         int r = 0;
 685
 686         switch(write_behind) {
 687         case 2:
 688                 if (start_loffset < len)
 689                         break;
 690                 start_loffset -= len;
 691                 /* fall through */
 692         case 1:
 693                 if (vp->v_filesize >= write_behind_minfilesize) {
 694                         r = cluster_wbuild(vp, NULL, blksize,
 695                                            start_loffset, len);
 696                 }
 697                 /* fall through */
 698         default:
 699                 /* fall through */
 700                 break;
 701         }
 702         return(r);
 703 }
 704
 705 /*
 706  * Do clustered write for FFS.
 707  *
 708  * Three cases:
 709  *      1. Write is not sequential (write asynchronously)
 710  *      Write is sequential:
 711  *      2.      beginning of cluster - begin cluster
 712  *      3.      middle of a cluster - add to cluster
 713  *      4.      end of a cluster - asynchronously write cluster
 714  */
 715 void
 716 cluster_write(struct buf *bp, off_t filesize, int blksize, int seqcount)
 717 {
 718         struct vnode *vp;
 719         off_t loffset;
 720         int maxclen, cursize;
 721         int async;
 722
 723         vp = bp->b_vp;
 724         if (vp->v_type == VREG)
 725                 async = vp->v_mount->mnt_flag & MNT_ASYNC;
 726         else
 727                 async = 0;
 728         loffset = bp->b_loffset;
 729         KASSERT(bp->b_loffset != NOOFFSET,
 730                 ("cluster_write: no buffer offset"));
 731
 732         /* Initialize vnode to beginning of file. */
 733         if (loffset == 0)
 734                 vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0;
 735
 736         if (vp->v_clen == 0 || loffset != vp->v_lastw + blksize ||
 737             bp->b_bio2.bio_offset == NOOFFSET ||
 738             (bp->b_bio2.bio_offset != vp->v_lasta + blksize)) {
 739                 maxclen = vmaxiosize(vp);
 740                 if (vp->v_clen != 0) {
 741                         /*
 742                          * Next block is not sequential.
 743                          *
 744                          * If we are not writing at end of file, the process
 745                          * seeked to another point in the file since its last
 746                          * write, or we have reached our maximum cluster size,
 747                          * then push the previous cluster. Otherwise try
 748                          * reallocating to make it sequential.
 749                          *
 750                          * Change to algorithm: only push previous cluster if
 751                          * it was sequential from the point of view of the
 752                          * seqcount heuristic, otherwise leave the buffer
 753                          * intact so we can potentially optimize the I/O
 754                          * later on in the buf_daemon or update daemon
 755                          * flush.
 756                          */
 757                         cursize = vp->v_lastw - vp->v_cstart + blksize;
 758                         if (bp->b_loffset + blksize < filesize ||
 759                             loffset != vp->v_lastw + blksize || vp->v_clen <= cursize) {
 760                                 if (!async && seqcount > 0) {
 761                                         cluster_wbuild_wb(vp, blksize,
 762                                                 vp->v_cstart, cursize);
 763                                 }
 764                         } else {
 765                                 struct buf **bpp, **endbp;
 766                                 struct cluster_save *buflist;
 767
 768                                 buflist = cluster_collectbufs(vp, bp, blksize);
 769                                 endbp = &buflist->bs_children
 770                                     [buflist->bs_nchildren - 1];
 771                                 if (VOP_REALLOCBLKS(vp, buflist)) {
 772                                         /*
 773                                          * Failed, push the previous cluster
 774                                          * if *really* writing sequentially
 775                                          * in the logical file (seqcount > 1),
 776                                          * otherwise delay it in the hopes that
 777                                          * the low level disk driver can
 778                                          * optimize the write ordering.
 779                                          */
 780                                         for (bpp = buflist->bs_children;
 781                                              bpp < endbp; bpp++)
 782                                                 brelse(*bpp);
 783                                         kfree(buflist, M_SEGMENT);
 784                                         if (seqcount > 1) {
 785                                                 cluster_wbuild_wb(vp,
 786                                                     blksize, vp->v_cstart,
 787                                                     cursize);
 788                                         }
 789                                 } else {
 790                                         /*
 791                                          * Succeeded, keep building cluster.
 792                                          */
 793                                         for (bpp = buflist->bs_children;
 794                                              bpp <= endbp; bpp++)
 795                                                 bdwrite(*bpp);
 796                                         kfree(buflist, M_SEGMENT);
 797                                         vp->v_lastw = loffset;
 798                                         vp->v_lasta = bp->b_bio2.bio_offset;
 799                                         return;
 800                                 }
 801                         }
 802                 }
 803                 /*
 804                  * Consider beginning a cluster. If at end of file, make
 805                  * cluster as large as possible, otherwise find size of
 806                  * existing cluster.
 807                  */
 808                 if ((vp->v_type == VREG) &&
 809                     bp->b_loffset + blksize < filesize &&
 810                     (bp->b_bio2.bio_offset == NOOFFSET) &&
 811                     (VOP_BMAP(vp, loffset, &bp->b_bio2.bio_offset, &maxclen, NULL, BUF_CMD_WRITE) ||
 812                      bp->b_bio2.bio_offset == NOOFFSET)) {
 813                         bawrite(bp);
 814                         vp->v_clen = 0;
 815                         vp->v_lasta = bp->b_bio2.bio_offset;
 816                         vp->v_cstart = loffset + blksize;
 817                         vp->v_lastw = loffset;
 818                         return;
 819                 }
 820                 if (maxclen > blksize)
 821                         vp->v_clen = maxclen - blksize;
 822                 else
 823                         vp->v_clen = 0;
 824                 if (!async && vp->v_clen == 0) { /* I/O not contiguous */
 825                         vp->v_cstart = loffset + blksize;
 826                         bawrite(bp);
 827                 } else {        /* Wait for rest of cluster */
 828                         vp->v_cstart = loffset;
 829                         bdwrite(bp);
 830                 }
 831         } else if (loffset == vp->v_cstart + vp->v_clen) {
 832                 /*
 833                  * At end of cluster, write it out if seqcount tells us we
 834                  * are operating sequentially, otherwise let the buf or
 835                  * update daemon handle it.
 836                  */
 837                 bdwrite(bp);
 838                 if (seqcount > 1)
 839                         cluster_wbuild_wb(vp, blksize, vp->v_cstart,
 840                                           vp->v_clen + blksize);
 841                 vp->v_clen = 0;
 842                 vp->v_cstart = loffset + blksize;
 843         } else if (vm_page_count_severe()) {
 844                 /*
 845                  * We are low on memory, get it going NOW
 846                  */
 847                 bawrite(bp);
 848         } else {
 849                 /*
 850                  * In the middle of a cluster, so just delay the I/O for now.
 851                  */
 852                 bdwrite(bp);
 853         }
 854         vp->v_lastw = loffset;
 855         vp->v_lasta = bp->b_bio2.bio_offset;
 856 }
 857
 858 /*
 859  * This is the clustered version of bawrite().  It works similarly to
 860  * cluster_write() except I/O on the buffer is guaranteed to occur.
 861  */
 862 int
 863 cluster_awrite(struct buf *bp)
 864 {
 865         int total;
 866
 867         /*
 868          * Don't bother if it isn't clusterable.
 869          */
 870         if ((bp->b_flags & B_CLUSTEROK) == 0 ||
 871             bp->b_vp == NULL ||
 872             (bp->b_vp->v_flag & VOBJBUF) == 0) {
 873                 total = bp->b_bufsize;
 874                 bawrite(bp);
 875                 return (total);
 876         }
 877
 878         total = cluster_wbuild(bp->b_vp, &bp, bp->b_bufsize,
 879                                bp->b_loffset, vmaxiosize(bp->b_vp));
 880         if (bp)
 881                 bawrite(bp);
 882
 883         return total;
 884 }
 885
 886 /*
 887  * This is an awful lot like cluster_rbuild...wish they could be combined.
 888  * The last lbn argument is the current block on which I/O is being
 889  * performed.  Check to see that it doesn't fall in the middle of
 890  * the current block (if last_bp == NULL).
 891  *
 892  * cluster_wbuild() normally does not guarantee anything.  If bpp is
 893  * non-NULL and cluster_wbuild() is able to incorporate it into the
 894  * I/O it will set *bpp to NULL, otherwise it will leave it alone and
 895  * the caller must dispose of *bpp.
 896  */
 897 static int
 898 cluster_wbuild(struct vnode *vp, struct buf **bpp,
 899                int blksize, off_t start_loffset, int bytes)
 900 {
 901         struct buf *bp, *tbp;
 902         int i, j;
 903         int totalwritten = 0;
 904         int must_initiate;
 905         int maxiosize = vmaxiosize(vp);
 906
 907         while (bytes > 0) {
 908                 /*
 909                  * If the buffer matches the passed locked & removed buffer
 910                  * we used the passed buffer (which might not be B_DELWRI).
 911                  *
 912                  * Otherwise locate the buffer and determine if it is
 913                  * compatible.
 914                  */
 915                 if (bpp && (*bpp)->b_loffset == start_loffset) {
 916                         tbp = *bpp;
 917                         *bpp = NULL;
 918                         bpp = NULL;
 919                 } else {
 920                         tbp = findblk(vp, start_loffset, FINDBLK_NBLOCK);
 921                         if (tbp == NULL ||
 922                             (tbp->b_flags & (B_LOCKED | B_INVAL | B_DELWRI)) !=
 923                              B_DELWRI ||
 924                             (LIST_FIRST(&tbp->b_dep) && buf_checkwrite(tbp))) {
 925                                 if (tbp)
 926                                         BUF_UNLOCK(tbp);
 927                                 start_loffset += blksize;
 928                                 bytes -= blksize;
 929                                 continue;
 930                         }
 931                         bremfree(tbp);
 932                 }
 933                 KKASSERT(tbp->b_cmd == BUF_CMD_DONE);
 934
 935                 /*
 936                  * Extra memory in the buffer, punt on this buffer.
 937                  * XXX we could handle this in most cases, but we would
 938                  * have to push the extra memory down to after our max
 939                  * possible cluster size and then potentially pull it back
 940                  * up if the cluster was terminated prematurely--too much
 941                  * hassle.
 942                  */
 943                 if (((tbp->b_flags & (B_CLUSTEROK|B_MALLOC)) != B_CLUSTEROK) ||
 944                     (tbp->b_bcount != tbp->b_bufsize) ||
 945                     (tbp->b_bcount != blksize) ||
 946                     (bytes == blksize) ||
 947                     ((bp = getpbuf_kva(&cluster_pbuf_freecnt)) == NULL)) {
 948                         totalwritten += tbp->b_bufsize;
 949                         bawrite(tbp);
 950                         start_loffset += blksize;
 951                         bytes -= blksize;
 952                         continue;
 953                 }
 954
 955                 /*
 956                  * Set up the pbuf.  Track our append point with b_bcount
 957                  * and b_bufsize.  b_bufsize is not used by the device but
 958                  * our caller uses it to loop clusters and we use it to
 959                  * detect a premature EOF on the block device.
 960                  */
 961                 bp->b_bcount = 0;
 962                 bp->b_bufsize = 0;
 963                 bp->b_xio.xio_npages = 0;
 964                 bp->b_loffset = tbp->b_loffset;
 965                 bp->b_bio2.bio_offset = tbp->b_bio2.bio_offset;
 966
 967                 /*
 968                  * We are synthesizing a buffer out of vm_page_t's, but
 969                  * if the block size is not page aligned then the starting
 970                  * address may not be either.  Inherit the b_data offset
 971                  * from the original buffer.
 972                  */
 973                 bp->b_data = (char *)((vm_offset_t)bp->b_data |
 974                     ((vm_offset_t)tbp->b_data & PAGE_MASK));
 975                 bp->b_flags &= ~B_ERROR;
 976                 bp->b_flags |= B_CLUSTER | B_BNOCLIP |
 977                         (tbp->b_flags & (B_VMIO | B_NEEDCOMMIT));
 978                 bp->b_bio1.bio_caller_info1.cluster_head = NULL;
 979                 bp->b_bio1.bio_caller_info2.cluster_tail = NULL;
 980
 981                 /*
 982                  * From this location in the file, scan forward to see
 983                  * if there are buffers with adjacent data that need to
 984                  * be written as well.
 985                  *
 986                  * IO *must* be initiated on index 0 at this point
 987                  * (particularly when called from cluster_awrite()).
 988                  */
 989                 for (i = 0; i < bytes; (i += blksize), (start_loffset += blksize)) {
 990                         if (i == 0) {
 991                                 must_initiate = 1;
 992                         } else {
 993                                 /*
 994                                  * Not first buffer.
 995                                  */
 996                                 must_initiate = 0;
 997                                 tbp = findblk(vp, start_loffset,
 998                                               FINDBLK_NBLOCK);
 999                                 /*
1000                                  * Buffer not found or could not be locked
1001                                  * non-blocking.
1002                                  */
1003                                 if (tbp == NULL)
1004                                         break;
1005
1006                                 /*
1007                                  * If it IS in core, but has different
1008                                  * characteristics, then don't cluster
1009                                  * with it.
1010                                  */
1011                                 if ((tbp->b_flags & (B_VMIO | B_CLUSTEROK |
1012                                      B_INVAL | B_DELWRI | B_NEEDCOMMIT))
1013                                     != (B_DELWRI | B_CLUSTEROK |
1014                                      (bp->b_flags & (B_VMIO | B_NEEDCOMMIT))) ||
1015                                     (tbp->b_flags & B_LOCKED)
1016                                 ) {
1017                                         BUF_UNLOCK(tbp);
1018                                         break;
1019                                 }
1020
1021                                 /*
1022                                  * Check that the combined cluster
1023                                  * would make sense with regard to pages
1024                                  * and would not be too large
1025                                  *
1026                                  * WARNING! buf_checkwrite() must be the last
1027                                  *          check made.  If it returns 0 then
1028                                  *          we must initiate the I/O.
1029                                  */
1030                                 if ((tbp->b_bcount != blksize) ||
1031                                   ((bp->b_bio2.bio_offset + i) !=
1032                                     tbp->b_bio2.bio_offset) ||
1033                                   ((tbp->b_xio.xio_npages + bp->b_xio.xio_npages) >
1034                                     (maxiosize / PAGE_SIZE)) ||
1035                                   (LIST_FIRST(&tbp->b_dep) &&
1036                                    buf_checkwrite(tbp))
1037                                 ) {
1038                                         BUF_UNLOCK(tbp);
1039                                         break;
1040                                 }
1041                                 if (LIST_FIRST(&tbp->b_dep))
1042                                         must_initiate = 1;
1043                                 /*
1044                                  * Ok, it's passed all the tests,
1045                                  * so remove it from the free list
1046                                  * and mark it busy. We will use it.
1047                                  */
1048                                 bremfree(tbp);
1049                                 KKASSERT(tbp->b_cmd == BUF_CMD_DONE);
1050                         }
1051
1052                         /*
1053                          * If the IO is via the VM then we do some
1054                          * special VM hackery (yuck).  Since the buffer's
1055                          * block size may not be page-aligned it is possible
1056                          * for a page to be shared between two buffers.  We
1057                          * have to get rid of the duplication when building
1058                          * the cluster.
1059                          */
1060                         if (tbp->b_flags & B_VMIO) {
1061                                 vm_page_t m;
1062
1063                                 /*
1064                                  * Try to avoid deadlocks with the VM system.
1065                                  * However, we cannot abort the I/O if
1066                                  * must_initiate is non-zero.
1067                                  */
1068                                 if (must_initiate == 0) {
1069                                         for (j = 0;
1070                                              j < tbp->b_xio.xio_npages;
1071                                              ++j) {
1072                                                 m = tbp->b_xio.xio_pages[j];
1073                                                 if (m->flags & PG_BUSY) {
1074                                                         bqrelse(tbp);
1075                                                         goto finishcluster;
1076                                                 }
1077                                         }
1078                                 }
1079
1080                                 for (j = 0; j < tbp->b_xio.xio_npages; ++j) {
1081                                         m = tbp->b_xio.xio_pages[j];
1082                                         vm_page_busy_wait(m, FALSE, "clurpg");
1083                                         vm_page_io_start(m);
1084                                         vm_page_wakeup(m);
1085                                         vm_object_pip_add(m->object, 1);
1086                                         if ((bp->b_xio.xio_npages == 0) ||
1087                                           (bp->b_xio.xio_pages[bp->b_xio.xio_npages - 1] != m)) {
1088                                                 bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m;
1089                                                 bp->b_xio.xio_npages++;
1090                                         }
1091                                 }
1092                         }
1093                         bp->b_bcount += blksize;
1094                         bp->b_bufsize += blksize;
1095
1096                         bundirty(tbp);
1097                         tbp->b_flags &= ~B_ERROR;
1098                         tbp->b_cmd = BUF_CMD_WRITE;
1099                         BUF_KERNPROC(tbp);
1100                         cluster_append(&bp->b_bio1, tbp);
1101
1102                         /*
1103                          * check for latent dependencies to be handled
1104                          */
1105                         if (LIST_FIRST(&tbp->b_dep) != NULL)
1106                                 buf_start(tbp);
1107                 }
1108         finishcluster:
1109                 pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
1110                             (vm_page_t *)bp->b_xio.xio_pages,
1111                             bp->b_xio.xio_npages);
1112                 if (bp->b_bufsize > bp->b_kvasize) {
1113                         panic("cluster_wbuild: b_bufsize(%d) "
1114                               "> b_kvasize(%d)\n",
1115                               bp->b_bufsize, bp->b_kvasize);
1116                 }
1117                 totalwritten += bp->b_bufsize;
1118                 bp->b_dirtyoff = 0;
1119                 bp->b_dirtyend = bp->b_bufsize;
1120                 bp->b_bio1.bio_done = cluster_callback;
1121                 bp->b_cmd = BUF_CMD_WRITE;
1122
1123                 vfs_busy_pages(vp, bp);
1124                 bsetrunningbufspace(bp, bp->b_bufsize);
1125                 BUF_KERNPROC(bp);
1126                 vn_strategy(vp, &bp->b_bio1);
1127
1128                 bytes -= i;
1129         }
1130         return totalwritten;
1131 }
1132
1133 /*
1134  * Collect together all the buffers in a cluster.
1135  * Plus add one additional buffer.
1136  */
1137 static struct cluster_save *
1138 cluster_collectbufs(struct vnode *vp, struct buf *last_bp, int blksize)
1139 {
1140         struct cluster_save *buflist;
1141         struct buf *bp;
1142         off_t loffset;
1143         int i, len;
1144
1145         len = (int)(vp->v_lastw - vp->v_cstart + blksize) / blksize;
1146         buflist = kmalloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist),
1147                          M_SEGMENT, M_WAITOK);
1148         buflist->bs_nchildren = 0;
1149         buflist->bs_children = (struct buf **) (buflist + 1);
1150         for (loffset = vp->v_cstart, i = 0; i < len; (loffset += blksize), i++) {
1151                 (void) bread(vp, loffset, last_bp->b_bcount, &bp);
1152                 buflist->bs_children[i] = bp;
1153                 if (bp->b_bio2.bio_offset == NOOFFSET) {
1154                         VOP_BMAP(bp->b_vp, bp->b_loffset,
1155                                  &bp->b_bio2.bio_offset,
1156                                  NULL, NULL, BUF_CMD_WRITE);
1157                 }
1158         }
1159         buflist->bs_children[i] = bp = last_bp;
1160         if (bp->b_bio2.bio_offset == NOOFFSET) {
1161                 VOP_BMAP(bp->b_vp, bp->b_loffset, &bp->b_bio2.bio_offset,
1162                          NULL, NULL, BUF_CMD_WRITE);
1163         }
1164         buflist->bs_nchildren = i + 1;
1165         return (buflist);
1166 }
1167
1168 void
1169 cluster_append(struct bio *bio, struct buf *tbp)
1170 {
1171         tbp->b_cluster_next = NULL;
1172         if (bio->bio_caller_info1.cluster_head == NULL) {
1173                 bio->bio_caller_info1.cluster_head = tbp;
1174                 bio->bio_caller_info2.cluster_tail = tbp;
1175         } else {
1176                 bio->bio_caller_info2.cluster_tail->b_cluster_next = tbp;
1177                 bio->bio_caller_info2.cluster_tail = tbp;
1178         }
1179 }
1180
1181 static
1182 void
1183 cluster_setram (struct buf *bp)
1184 {
1185         bp->b_flags |= B_RAM;
1186         if (bp->b_xio.xio_npages)
1187                 vm_page_flag_set(bp->b_xio.xio_pages[0], PG_RAM);
1188 }