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