src/WINNT/afsd/cm_buf.c

   1 /*
   2  * Copyright 2000, International Business Machines Corporation and others.
   3  * All Rights Reserved.
   4  *
   5  * This software has been released under the terms of the IBM Public
   6  * License.  For details, see the LICENSE file in the top-level source
   7  * directory or online at http://www.openafs.org/dl/license10.html
   8  */
   9
  10 /* Copyright (C) 1994 Cazamar Systems, Inc. */
  11
  12 #include <afs/param.h>
  13 #include <afs/stds.h>
  14
  15 #ifndef DJGPP
  16 #include <windows.h>
  17 #endif
  18 #include <osi.h>
  19 #include <malloc.h>
  20 #include <stdio.h>
  21 #include <assert.h>
  22
  23 #include "afsd.h"
  24
  25 void afsi_log();
  26
  27 /* This module implements the buffer package used by the local transaction
  28  * system (cm).  It is initialized by calling cm_Init, which calls buf_Init;
  29  * it must be initalized before any of its main routines are called.
  30  *
  31  * Each buffer is hashed into a hash table by file ID and offset, and if its
  32  * reference count is zero, it is also in a free list.
  33  *
  34  * There are two locks involved in buffer processing.  The global lock
  35  * buf_globalLock protects all of the global variables defined in this module,
  36  * the reference counts and hash pointers in the actual cm_buf_t structures,
  37  * and the LRU queue pointers in the buffer structures.
  38  *
  39  * The mutexes in the buffer structures protect the remaining fields in the
  40  * buffers, as well the data itself.
  41  *
  42  * The locking hierarchy here is this:
  43  *
  44  * - resv multiple simul. buffers reservation
  45  * - lock buffer I/O flags
  46  * - lock buffer's mutex
  47  * - lock buf_globalLock
  48  *
  49  */
  50
  51 /* global debugging log */
  52 osi_log_t *buf_logp = NULL;
  53
  54 /* Global lock protecting hash tables and free lists */
  55 osi_rwlock_t buf_globalLock;
  56
  57 /* ptr to head of the free list (most recently used) and the
  58  * tail (the guy to remove first).  We use osi_Q* functions
  59  * to put stuff in buf_freeListp, and maintain the end
  60  * pointer manually
  61  */
  62 cm_buf_t *buf_freeListp;
  63 cm_buf_t *buf_freeListEndp;
  64
  65 /* a pointer to a list of all buffers, just so that we can find them
  66  * easily for debugging, and for the incr syncer.  Locked under
  67  * the global lock.
  68  */
  69 cm_buf_t *buf_allp;
  70
  71 /* defaults setup; these variables may be manually assigned into
  72  * before calling cm_Init, as a way of changing these defaults.
  73  */
  74 long buf_nbuffers = CM_BUF_BUFFERS;
  75 long buf_nOrigBuffers;
  76 long buf_bufferSize = CM_BUF_SIZE;
  77 long buf_hashSize = CM_BUF_HASHSIZE;
  78
  79 #ifndef DJGPP
  80 static
  81 HANDLE CacheHandle;
  82
  83 static
  84 SYSTEM_INFO sysInfo;
  85 #endif /* !DJGPP */
  86
  87 /* buffer reservation variables */
  88 long buf_reservedBufs;
  89 long buf_maxReservedBufs;
  90 int buf_reserveWaiting;
  91
  92 /* callouts for reading and writing data, etc */
  93 cm_buf_ops_t *cm_buf_opsp;
  94
  95 /* pointer to hash table; size computed dynamically */
  96 cm_buf_t **buf_hashTablepp;
  97
  98 /* another hash table */
  99 cm_buf_t **buf_fileHashTablepp;
 100
 101 #ifdef DISKCACHE95
 102 /* for experimental disk caching support in Win95 client */
 103 cm_buf_t *buf_diskFreeListp;
 104 cm_buf_t *buf_diskFreeListEndp;
 105 cm_buf_t *buf_diskAllp;
 106 extern int cm_diskCacheEnabled;
 107 #endif /* DISKCACHE95 */
 108
 109 /* hold a reference to an already held buffer */
 110 void buf_Hold(cm_buf_t *bp)
 111 {
 112         lock_ObtainWrite(&buf_globalLock);
 113         bp->refCount++;
 114         lock_ReleaseWrite(&buf_globalLock);
 115 }
 116
 117 /* incremental sync daemon.  Writes 1/10th of all the buffers every 5000 ms */
 118 void buf_IncrSyncer(long parm)
 119 {
 120         cm_buf_t *bp;                   /* buffer we're hacking on; held */
 121         long i;                         /* counter */
 122         long nAtOnce;                   /* how many to do at once */
 123         cm_req_t req;
 124
 125         lock_ObtainWrite(&buf_globalLock);
 126         bp = buf_allp;
 127         bp->refCount++;
 128         lock_ReleaseWrite(&buf_globalLock);
 129         nAtOnce = buf_nbuffers / 10;
 130         while (1) {
 131 #ifndef DJGPP
 132                 i = SleepEx(5000, 1);
 133                 if (i != 0) continue;
 134 #else
 135                 thrd_Sleep(5000);
 136 #endif /* DJGPP */
 137
 138                 /* now go through our percentage of the buffers */
 139                 for(i=0; i<nAtOnce; i++) {
 140                         /* don't want its identity changing while we're
 141                          * messing with it, so must do all of this with
 142                          * bp held.
 143                          */
 144
 145                         /* start cleaning the buffer; don't touch log pages since
 146                          * the log code counts on knowing exactly who is writing
 147                          * a log page at any given instant.
 148                          */
 149                         cm_InitReq(&req);
 150                         req.flags |= CM_REQ_NORETRY;
 151                         buf_CleanAsync(bp, &req);
 152
 153                         /* now advance to the next buffer; the allp chain never changes,
 154                          * and so can be followed even when holding no locks.
 155                          */
 156                         lock_ObtainWrite(&buf_globalLock);
 157                         buf_LockedRelease(bp);
 158                         bp = bp->allp;
 159                         if (!bp) bp = buf_allp;
 160                         bp->refCount++;
 161                         lock_ReleaseWrite(&buf_globalLock);
 162                 }       /* for loop over a bunch of buffers */
 163         }               /* whole daemon's while loop */
 164 }
 165
 166 #ifndef DJGPP
 167 /* Create a security attribute structure suitable for use when the cache file
 168  * is created.  What we mainly want is that only the administrator should be
 169  * able to do anything with the file.  We create an ACL with only one entry,
 170  * an entry that grants all rights to the administrator.
 171  */
 172 PSECURITY_ATTRIBUTES CreateCacheFileSA()
 173 {
 174         PSECURITY_ATTRIBUTES psa;
 175         PSECURITY_DESCRIPTOR psd;
 176         SID_IDENTIFIER_AUTHORITY authority = SECURITY_NT_AUTHORITY;
 177         PSID AdminSID;
 178         DWORD AdminSIDlength;
 179         PACL AdminOnlyACL;
 180         DWORD ACLlength;
 181
 182         /* Get Administrator SID */
 183         AllocateAndInitializeSid(&authority, 2,
 184                                  SECURITY_BUILTIN_DOMAIN_RID,
 185                                  DOMAIN_ALIAS_RID_ADMINS,
 186                                  0, 0, 0, 0, 0, 0,
 187                                  &AdminSID);
 188
 189         /* Create Administrator-only ACL */
 190         AdminSIDlength = GetLengthSid(AdminSID);
 191         ACLlength = sizeof(ACL) + sizeof(ACCESS_ALLOWED_ACE)
 192                         + AdminSIDlength - sizeof(DWORD);
 193         AdminOnlyACL = GlobalAlloc(GMEM_FIXED, ACLlength);
 194         InitializeAcl(AdminOnlyACL, ACLlength, ACL_REVISION);
 195         AddAccessAllowedAce(AdminOnlyACL, ACL_REVISION,
 196                             STANDARD_RIGHTS_ALL | SPECIFIC_RIGHTS_ALL,
 197                             AdminSID);
 198
 199         /* Create security descriptor */
 200         psd = GlobalAlloc(GMEM_FIXED, sizeof(SECURITY_DESCRIPTOR));
 201         InitializeSecurityDescriptor(psd, SECURITY_DESCRIPTOR_REVISION);
 202         SetSecurityDescriptorDacl(psd, TRUE, AdminOnlyACL, FALSE);
 203
 204         /* Create security attributes structure */
 205         psa = GlobalAlloc(GMEM_FIXED, sizeof(SECURITY_ATTRIBUTES));
 206         psa->nLength = sizeof(SECURITY_ATTRIBUTES);
 207         psa->lpSecurityDescriptor = psd;
 208         psa->bInheritHandle = TRUE;
 209
 210         return psa;
 211 }
 212 #endif /* !DJGPP */
 213
 214 #ifndef DJGPP
 215 /* Free a security attribute structure created by CreateCacheFileSA() */
 216 VOID FreeCacheFileSA(PSECURITY_ATTRIBUTES psa)
 217 {
 218         BOOL b1, b2;
 219         PACL pAcl;
 220
 221         GetSecurityDescriptorDacl(psa->lpSecurityDescriptor, &b1, &pAcl, &b2);
 222         GlobalFree(pAcl);
 223         GlobalFree(psa->lpSecurityDescriptor);
 224         GlobalFree(psa);
 225 }
 226 #endif /* !DJGPP */
 227
 228 /* initialize the buffer package; called with no locks
 229  * held during the initialization phase.
 230  */
 231 long buf_Init(cm_buf_ops_t *opsp)
 232 {
 233         static osi_once_t once;
 234         cm_buf_t *bp;
 235         long sectorSize;
 236         thread_t phandle;
 237 #ifndef DJGPP
 238         HANDLE hf, hm;
 239         PSECURITY_ATTRIBUTES psa;
 240 #endif /* !DJGPP */
 241         long i;
 242         unsigned long pid;
 243         char *data;
 244         long cs;
 245
 246 #ifndef DJGPP
 247         /* Get system info; all we really want is the allocation granularity */
 248         GetSystemInfo(&sysInfo);
 249 #endif /* !DJGPP */
 250
 251         /* Have to be able to reserve a whole chunk */
 252         if (((buf_nbuffers - 3) * buf_bufferSize) < cm_chunkSize)
 253                 return CM_ERROR_TOOFEWBUFS;
 254
 255         /* recall for callouts */
 256         cm_buf_opsp = opsp;
 257
 258         if (osi_Once(&once)) {
 259                 /* initialize global locks */
 260                 lock_InitializeRWLock(&buf_globalLock, "Global buffer lock");
 261
 262 #ifndef DJGPP
 263                 /*
 264                  * Cache file mapping constrained by
 265                  * system allocation granularity;
 266                  * round up, assuming granularity is a power of two
 267                  */
 268                 cs = buf_nbuffers * buf_bufferSize;
 269                 cs = (cs + (sysInfo.dwAllocationGranularity - 1))
 270                         & ~(sysInfo.dwAllocationGranularity - 1);
 271                 if (cs != buf_nbuffers * buf_bufferSize) {
 272                         buf_nbuffers = cs / buf_bufferSize;
 273                         afsi_log("Cache size rounded up to %d buffers",
 274                                  buf_nbuffers);
 275                 }
 276 #endif /* !DJGPP */
 277
 278                 /* remember this for those who want to reset it */
 279                 buf_nOrigBuffers = buf_nbuffers;
 280
 281                 /* lower hash size to a prime number */
 282                 buf_hashSize = osi_PrimeLessThan(buf_hashSize);
 283
 284                 /* create hash table */
 285                 buf_hashTablepp = malloc(buf_hashSize * sizeof(cm_buf_t *));
 286                 memset((void *)buf_hashTablepp, 0,
 287                         buf_hashSize * sizeof(cm_buf_t *));
 288
 289                 /* another hash table */
 290                 buf_fileHashTablepp = malloc(buf_hashSize * sizeof(cm_buf_t *));
 291                 memset((void *)buf_fileHashTablepp, 0,
 292                         buf_hashSize * sizeof(cm_buf_t *));
 293
 294                 /* min value for which this works */
 295                 sectorSize = 1;
 296
 297 #ifndef DJGPP
 298                 /* Reserve buffer space by mapping cache file */
 299                 psa = CreateCacheFileSA();
 300                 hf = CreateFile(cm_CachePath,
 301                         GENERIC_READ | GENERIC_WRITE,
 302                         FILE_SHARE_READ | FILE_SHARE_WRITE,
 303                         psa,
 304                         OPEN_ALWAYS,
 305                         FILE_ATTRIBUTE_NORMAL,
 306                         NULL);
 307                 if (hf == INVALID_HANDLE_VALUE) {
 308                         afsi_log("create file error %d", GetLastError());
 309                         return CM_ERROR_INVAL;
 310                 }
 311                 FreeCacheFileSA(psa);
 312                 CacheHandle = hf;
 313                 hm = CreateFileMapping(hf,
 314                         NULL,
 315                         PAGE_READWRITE,
 316                         0, buf_nbuffers * buf_bufferSize,
 317                         NULL);
 318                 if (hm == NULL) {
 319                         if (GetLastError() == ERROR_DISK_FULL) {
 320                                 afsi_log("Error creating cache file mapping: disk full");
 321                                 return CM_ERROR_TOOMANYBUFS;
 322                         }
 323                         return CM_ERROR_INVAL;
 324                 }
 325                 data = MapViewOfFile(hm,
 326                         FILE_MAP_ALL_ACCESS,
 327                         0, 0,
 328                         buf_nbuffers * buf_bufferSize);
 329                 if (data == NULL) {
 330                         CloseHandle(hf);
 331                         CloseHandle(hm);
 332                         return CM_ERROR_INVAL;
 333                 }
 334                 CloseHandle(hm);
 335 #else
 336                 /* djgpp doesn't support memory mapped files */
 337                 data = malloc(buf_nbuffers * buf_bufferSize);
 338 #endif /* !DJGPP */
 339
 340                 /* create buffer headers and put in free list */
 341                 bp = malloc(buf_nbuffers * sizeof(cm_buf_t));
 342                 buf_allp = NULL;
 343                 for(i=0; i<buf_nbuffers; i++) {
 344                         /* allocate and zero some storage */
 345                         memset(bp, 0, sizeof(cm_buf_t));
 346
 347                         /* thread on list of all buffers */
 348                         bp->allp = buf_allp;
 349                         buf_allp = bp;
 350
 351                         osi_QAdd((osi_queue_t **)&buf_freeListp, &bp->q);
 352                         bp->flags |= CM_BUF_INLRU;
 353                         lock_InitializeMutex(&bp->mx, "Buffer mutex");
 354
 355                         /* grab appropriate number of bytes from aligned zone */
 356                         bp->datap = data;
 357
 358                         /* setup last buffer pointer */
 359                         if (i == 0)
 360                                 buf_freeListEndp = bp;
 361
 362                         /* next */
 363                         bp++;
 364                         data += buf_bufferSize;
 365                 }
 366
 367                 /* none reserved at first */
 368                 buf_reservedBufs = 0;
 369
 370                 /* just for safety's sake */
 371                 buf_maxReservedBufs = buf_nbuffers - 3;
 372
 373                 /* init the buffer trace log */
 374                 buf_logp = osi_LogCreate("buffer", 10);
 375
 376                 osi_EndOnce(&once);
 377
 378                 /* and create the incr-syncer */
 379                 phandle = thrd_Create(0, 0,
 380                                       (ThreadFunc) buf_IncrSyncer, 0, 0, &pid,
 381                                       "buf_IncrSyncer");
 382
 383                 osi_assertx(phandle != NULL, "buf: can't create incremental sync proc");
 384 #ifndef DJGPP
 385                 CloseHandle(phandle);
 386 #endif /* !DJGPP */
 387         }
 388
 389         return 0;
 390 }
 391
 392 /* add nbuffers to the buffer pool, if possible.
 393  * Called with no locks held.
 394  */
 395 long buf_AddBuffers(long nbuffers)
 396 {
 397         cm_buf_t *bp;
 398         int i;
 399         char *data;
 400 #ifndef DJGPP
 401         HANDLE hm;
 402         long cs;
 403
 404         /*
 405          * Cache file mapping constrained by
 406          * system allocation granularity;
 407          * round up, assuming granularity is a power of two;
 408          * assume existing cache size is already rounded
 409          */
 410         cs = nbuffers * buf_bufferSize;
 411         cs = (cs + (sysInfo.dwAllocationGranularity - 1))
 412                 & ~(sysInfo.dwAllocationGranularity - 1);
 413         if (cs != nbuffers * buf_bufferSize) {
 414                 nbuffers = cs / buf_bufferSize;
 415         }
 416
 417         /* Reserve additional buffer space by remapping cache file */
 418         hm = CreateFileMapping(CacheHandle,
 419                 NULL,
 420                 PAGE_READWRITE,
 421                 0, (buf_nbuffers + nbuffers) * buf_bufferSize,
 422                 NULL);
 423         if (hm == NULL) {
 424                 if (GetLastError() == ERROR_DISK_FULL)
 425                         return CM_ERROR_TOOMANYBUFS;
 426                 else
 427                         return CM_ERROR_INVAL;
 428         }
 429         data = MapViewOfFile(hm,
 430                 FILE_MAP_ALL_ACCESS,
 431                 0, buf_nbuffers * buf_bufferSize,
 432                 nbuffers * buf_bufferSize);
 433         if (data == NULL) {
 434                 CloseHandle(hm);
 435                 return CM_ERROR_INVAL;
 436         }
 437         CloseHandle(hm);
 438 #else
 439         data = malloc(buf_nbuffers * buf_bufferSize);
 440 #endif /* DJGPP */
 441
 442         /* Create buffer headers and put in free list */
 443         bp = malloc(nbuffers * sizeof(*bp));
 444
 445         for(i=0; i<nbuffers; i++) {
 446                 memset(bp, 0, sizeof(*bp));
 447
 448                 lock_InitializeMutex(&bp->mx, "cm_buf_t");
 449
 450                 /* grab appropriate number of bytes from aligned zone */
 451                 bp->datap = data;
 452
 453                 bp->flags |= CM_BUF_INLRU;
 454
 455                 lock_ObtainWrite(&buf_globalLock);
 456                 /* note that buf_allp chain is covered by buf_globalLock now */
 457                 bp->allp = buf_allp;
 458                 buf_allp = bp;
 459                 osi_QAdd((osi_queue_t **) &buf_freeListp, &bp->q);
 460                 if (!buf_freeListEndp) buf_freeListEndp = bp;
 461                 buf_nbuffers++;
 462                 lock_ReleaseWrite(&buf_globalLock);
 463
 464                 bp++;
 465                 data += buf_bufferSize;
 466
 467         }        /* for loop over all buffers */
 468
 469         return 0;
 470 }
 471
 472 /* interface to set the number of buffers to an exact figure.
 473  * Called with no locks held.
 474  */
 475 long buf_SetNBuffers(long nbuffers)
 476 {
 477         if (nbuffers < 10) return CM_ERROR_INVAL;
 478         if (nbuffers == buf_nbuffers) return 0;
 479         else if (nbuffers > buf_nbuffers)
 480                 return buf_AddBuffers(nbuffers - buf_nbuffers);
 481         else return CM_ERROR_INVAL;
 482 }
 483
 484 /* release a buffer.  Buffer must be referenced, but unlocked. */
 485 void buf_Release(cm_buf_t *bp)
 486 {
 487         lock_ObtainWrite(&buf_globalLock);
 488         buf_LockedRelease(bp);
 489         lock_ReleaseWrite(&buf_globalLock);
 490 }
 491
 492 /* wait for reading or writing to clear; called with write-locked
 493  * buffer, and returns with locked buffer.
 494  */
 495 void buf_WaitIO(cm_buf_t *bp)
 496 {
 497         while (1) {
 498                 /* if no IO is happening, we're done */
 499                 if (!(bp->flags & (CM_BUF_READING | CM_BUF_WRITING)))
 500                         break;
 501
 502                 /* otherwise I/O is happening, but some other thread is waiting for
 503                  * the I/O already.  Wait for that guy to figure out what happened,
 504                  * and then check again.
 505                  */
 506                 bp->flags |= CM_BUF_WAITING;
 507                 osi_SleepM((long) bp, &bp->mx);
 508                 lock_ObtainMutex(&bp->mx);
 509                 osi_Log1(buf_logp, "buf_WaitIO conflict wait done for 0x%x", bp);
 510         }
 511
 512         /* if we get here, the IO is done, but we may have to wakeup people waiting for
 513          * the I/O to complete.  Do so.
 514          */
 515         if (bp->flags & CM_BUF_WAITING) {
 516                 bp->flags &= ~CM_BUF_WAITING;
 517                 osi_Wakeup((long) bp);
 518         }
 519         osi_Log1(buf_logp, "WaitIO finished wait for bp 0x%x", (long) bp);
 520 }
 521
 522 /* code to drop reference count while holding buf_globalLock */
 523 void buf_LockedRelease(cm_buf_t *bp)
 524 {
 525         /* ensure that we're in the LRU queue if our ref count is 0 */
 526         osi_assert(bp->refCount > 0);
 527         if (--bp->refCount == 0) {
 528                 if (!(bp->flags & CM_BUF_INLRU)) {
 529                         osi_QAdd((osi_queue_t **) &buf_freeListp, &bp->q);
 530
 531                         /* watch for transition from empty to one element */
 532                         if (!buf_freeListEndp)
 533                                 buf_freeListEndp = buf_freeListp;
 534                         bp->flags |= CM_BUF_INLRU;
 535                 }
 536         }
 537 }
 538
 539 /* find a buffer, if any, for a particular file ID and offset.  Assumes
 540  * that buf_globalLock is write locked when called.
 541  */
 542 cm_buf_t *buf_LockedFind(struct cm_scache *scp, osi_hyper_t *offsetp)
 543 {
 544         long i;
 545         cm_buf_t *bp;
 546
 547         i = BUF_HASH(&scp->fid, offsetp);
 548         for(bp = buf_hashTablepp[i]; bp; bp=bp->hashp) {
 549                 if (cm_FidCmp(&scp->fid, &bp->fid) == 0
 550                         && offsetp->LowPart == bp->offset.LowPart
 551                         && offsetp->HighPart == bp->offset.HighPart) {
 552                         bp->refCount++;
 553                         break;
 554                 }
 555         }
 556
 557         /* return whatever we found, if anything */
 558         return bp;
 559 }
 560
 561 /* find a buffer with offset *offsetp for vnode *scp.  Called
 562  * with no locks held.
 563  */
 564 cm_buf_t *buf_Find(struct cm_scache *scp, osi_hyper_t *offsetp)
 565 {
 566         cm_buf_t *bp;
 567
 568         lock_ObtainWrite(&buf_globalLock);
 569         bp = buf_LockedFind(scp, offsetp);
 570         lock_ReleaseWrite(&buf_globalLock);
 571
 572         return bp;
 573 }
 574
 575 /* start cleaning I/O on this buffer.  Buffer must be write locked, and is returned
 576  * write-locked.
 577  *
 578  * Makes sure that there's only one person writing this block
 579  * at any given time, and also ensures that the log is forced sufficiently far,
 580  * if this buffer contains logged data.
 581  */
 582 void buf_LockedCleanAsync(cm_buf_t *bp, cm_req_t *reqp)
 583 {
 584         long code;
 585
 586         code = 0;
 587         while ((bp->flags & (CM_BUF_WRITING | CM_BUF_DIRTY)) == CM_BUF_DIRTY) {
 588                 lock_ReleaseMutex(&bp->mx);
 589
 590                 code = (*cm_buf_opsp->Writep)(&bp->fid, &bp->offset,
 591                                                 buf_bufferSize, 0, bp->userp,
 592                                                 reqp);
 593
 594                 lock_ObtainMutex(&bp->mx);
 595                 if (code) break;
 596
 597 #ifdef DISKCACHE95
 598                 /* Disk cache support */
 599                 /* write buffer to disk cache (synchronous for now) */
 600                 diskcache_Update(bp->dcp, bp->datap, buf_bufferSize, bp->dataVersion);
 601 #endif /* DISKCACHE95 */
 602         };
 603
 604         /* do logging after call to GetLastError, or else */
 605         osi_Log2(buf_logp, "buf_CleanAsync starts I/O on 0x%x, done=%d", bp, code);
 606
 607         /* if someone was waiting for the I/O that just completed or failed,
 608          * wake them up.
 609          */
 610         if (bp->flags & CM_BUF_WAITING) {
 611                 /* turn off flags and wakeup users */
 612                 bp->flags &= ~CM_BUF_WAITING;
 613                 osi_Wakeup((long) bp);
 614         }
 615 }
 616
 617 /* Called with a zero-ref count buffer and with the buf_globalLock write locked.
 618  * recycles the buffer, and leaves it ready for reuse with a ref count of 1.
 619  * The buffer must already be clean, and no I/O should be happening to it.
 620  */
 621 void buf_Recycle(cm_buf_t *bp)
 622 {
 623         int i;
 624         cm_buf_t **lbpp;
 625         cm_buf_t *tbp;
 626         cm_buf_t *prevBp, *nextBp;
 627
 628         /* if we get here, we know that the buffer still has a 0 ref count,
 629          * and that it is clean and has no currently pending I/O.  This is
 630          * the dude to return.
 631          * Remember that as long as the ref count is 0, we know that we won't
 632          * have any lock conflicts, so we can grab the buffer lock out of
 633          * order in the locking hierarchy.
 634          */
 635         osi_Log2(buf_logp,
 636                 "buf_Recycle recycles 0x%x, off 0x%x",
 637                 bp, bp->offset.LowPart);
 638
 639         osi_assert(bp->refCount == 0);
 640         osi_assert(!(bp->flags & (CM_BUF_READING | CM_BUF_WRITING | CM_BUF_DIRTY)));
 641         lock_AssertWrite(&buf_globalLock);
 642
 643         if (bp->flags & CM_BUF_INHASH) {
 644                 /* Remove from hash */
 645
 646                 i = BUF_HASH(&bp->fid, &bp->offset);
 647                 lbpp = &(buf_hashTablepp[i]);
 648                 for(tbp = *lbpp; tbp; lbpp = &tbp->hashp, tbp = *lbpp) {
 649                         if (tbp == bp) break;
 650                 }
 651
 652                 /* we better find it */
 653                 osi_assertx(tbp != NULL, "buf_GetNewLocked: hash table screwup");
 654
 655                 *lbpp = bp->hashp;      /* hash out */
 656
 657                 /* Remove from file hash */
 658
 659                 i = BUF_FILEHASH(&bp->fid);
 660                 prevBp = bp->fileHashBackp;
 661                 nextBp = bp->fileHashp;
 662                 if (prevBp)
 663                         prevBp->fileHashp = nextBp;
 664                 else
 665                         buf_fileHashTablepp[i] = nextBp;
 666                 if (nextBp)
 667                         nextBp->fileHashBackp = prevBp;
 668
 669                 bp->flags &= ~CM_BUF_INHASH;
 670         }
 671
 672         /* bump the soft reference counter now, to invalidate softRefs; no
 673          * wakeup is required since people don't sleep waiting for this
 674          * counter to change.
 675          */
 676         bp->idCounter++;
 677
 678         /* make the fid unrecognizable */
 679         memset(&bp->fid, 0, sizeof(bp->fid));
 680 }
 681
 682 /* recycle a buffer, removing it from the free list, hashing in its new identity
 683  * and returning it write-locked so that no one can use it.  Called without
 684  * any locks held, and can return an error if it loses the race condition and
 685  * finds that someone else created the desired buffer.
 686  *
 687  * If success is returned, the buffer is returned write-locked.
 688  *
 689  * May be called with null scp and offsetp, if we're just trying to reclaim some
 690  * space from the buffer pool.  In that case, the buffer will be returned
 691  * without being hashed into the hash table.
 692  */
 693 long buf_GetNewLocked(struct cm_scache *scp, osi_hyper_t *offsetp, cm_buf_t **bufpp)
 694 {
 695         cm_buf_t *bp;           /* buffer we're dealing with */
 696         cm_buf_t *nextBp;       /* next buffer in file hash chain */
 697         long i;                 /* temp */
 698         cm_req_t req;
 699
 700         cm_InitReq(&req);       /* just in case */
 701
 702         while(1) {
 703 retry:
 704                 lock_ObtainWrite(&buf_globalLock);
 705                 /* check to see if we lost the race */
 706                 if (scp) {
 707                         if (bp = buf_LockedFind(scp, offsetp)) {
 708                                 bp->refCount--;
 709                                 lock_ReleaseWrite(&buf_globalLock);
 710                                 return CM_BUF_EXISTS;
 711                         }
 712                 }
 713
 714                 /* for debugging, assert free list isn't empty, although we
 715                  * really should try waiting for a running tranasction to finish
 716                  * instead of this; or better, we should have a transaction
 717                  * throttler prevent us from entering this situation.
 718                  */
 719                 osi_assertx(buf_freeListEndp != NULL, "buf_GetNewLocked: no free buffers");
 720
 721                 /* look at all buffers in free list, some of which may temp.
 722                  * have high refcounts and which then should be skipped,
 723                  * starting cleaning I/O for those which are dirty.  If we find
 724                  * a clean buffer, we rehash it, lock it and return it.
 725                  */
 726                 for(bp = buf_freeListEndp; bp; bp=(cm_buf_t *) osi_QPrev(&bp->q)) {
 727                         /* check to see if it really has zero ref count.  This
 728                          * code can bump refcounts, at least, so it may not be
 729                          * zero.
 730                          */
 731                         if (bp->refCount > 0) continue;
 732
 733                         /* we don't have to lock buffer itself, since the ref
 734                          * count is 0 and we know it will stay zero as long as
 735                          * we hold the global lock.
 736                          */
 737
 738                         /* don't recycle someone in our own chunk */
 739                         if (!cm_FidCmp(&bp->fid, &scp->fid)
 740                             && (bp->offset.LowPart & (-cm_chunkSize))
 741                                   == (offsetp->LowPart & (-cm_chunkSize)))
 742                                 continue;
 743
 744                         /* if this page is being filled (!) or cleaned, see if
 745                          * the I/O has completed.  If not, skip it, otherwise
 746                          * do the final processing for the I/O.
 747                          */
 748                         if (bp->flags & (CM_BUF_READING | CM_BUF_WRITING)) {
 749                                 /* probably shouldn't do this much work while
 750                                  * holding the big lock?  Watch for contention
 751                                  * here.
 752                                  */
 753                                 continue;
 754                         }
 755
 756                         if (bp->flags & CM_BUF_DIRTY) {
 757                                 /* if the buffer is dirty, start cleaning it and
 758                                  * move on to the next buffer.  We do this with
 759                                  * just the lock required to minimize contention
 760                                  * on the big lock.
 761                                  */
 762                                 bp->refCount++;
 763                                 lock_ReleaseWrite(&buf_globalLock);
 764
 765                                 /* grab required lock and clean; this only
 766                                  * starts the I/O.  By the time we're back,
 767                                  * it'll still be marked dirty, but it will also
 768                                  * have the WRITING flag set, so we won't get
 769                                  * back here.
 770                                  */
 771                                 buf_CleanAsync(bp, &req);
 772
 773                                 /* now put it back and go around again */
 774                                 buf_Release(bp);
 775                                 goto retry;
 776                         }
 777
 778                         /* if we get here, we know that the buffer still has a 0
 779                          * ref count, and that it is clean and has no currently
 780                          * pending I/O.  This is the dude to return.
 781                          * Remember that as long as the ref count is 0, we know
 782                          * that we won't have any lock conflicts, so we can grab
 783                          * the buffer lock out of order in the locking hierarchy.
 784                          */
 785                         buf_Recycle(bp);
 786
 787                         /* clean up junk flags */
 788                         bp->flags &= ~(CM_BUF_EOF | CM_BUF_ERROR);
 789                         bp->dataVersion = -1;   /* unknown so far */
 790
 791                         /* now hash in as our new buffer, and give it the
 792                          * appropriate label, if requested.
 793                          */
 794                         if (scp) {
 795                                 bp->flags |= CM_BUF_INHASH;
 796                                 bp->fid = scp->fid;
 797                                 bp->offset = *offsetp;
 798                                 i = BUF_HASH(&scp->fid, offsetp);
 799                                 bp->hashp = buf_hashTablepp[i];
 800                                 buf_hashTablepp[i] = bp;
 801                                 i = BUF_FILEHASH(&scp->fid);
 802                                 nextBp = buf_fileHashTablepp[i];
 803                                 bp->fileHashp = nextBp;
 804                                 bp->fileHashBackp = NULL;
 805                                 if (nextBp)
 806                                         nextBp->fileHashBackp = bp;
 807                                 buf_fileHashTablepp[i] = bp;
 808                         }
 809
 810                         /* prepare to return it.  Start by giving it a good
 811                          * refcount */
 812                         bp->refCount = 1;
 813
 814                         /* and since it has a non-zero ref count, we should move
 815                          * it from the lru queue.  It better be still there,
 816                          * since we've held the global (big) lock since we found
 817                          * it there.
 818                          */
 819                         osi_assertx(bp->flags & CM_BUF_INLRU,
 820                                     "buf_GetNewLocked: LRU screwup");
 821                         if (buf_freeListEndp == bp) {
 822                                 /* we're the last guy in this queue, so maintain it */
 823                                 buf_freeListEndp = (cm_buf_t *) osi_QPrev(&bp->q);
 824                         }
 825                         osi_QRemove((osi_queue_t **) &buf_freeListp, &bp->q);
 826                         bp->flags &= ~CM_BUF_INLRU;
 827
 828                         /* finally, grab the mutex so that people don't use it
 829                          * before the caller fills it with data.  Again, no one
 830                          * should have been able to get to this dude to lock it.
 831                          */
 832                         osi_assertx(lock_TryMutex(&bp->mx),
 833                                     "buf_GetNewLocked: TryMutex failed");
 834
 835                         lock_ReleaseWrite(&buf_globalLock);
 836                         *bufpp = bp;
 837                         return 0;
 838                 } /* for all buffers in lru queue */
 839                 lock_ReleaseWrite(&buf_globalLock);
 840         }       /* while loop over everything */
 841         /* not reached */
 842 } /* the proc */
 843
 844 /* get a page, returning it held but unlocked.  Doesn't fill in the page
 845  * with I/O, since we're going to write the whole thing new.
 846  */
 847 long buf_GetNew(struct cm_scache *scp, osi_hyper_t *offsetp, cm_buf_t **bufpp)
 848 {
 849         cm_buf_t *bp;
 850         long code;
 851         osi_hyper_t pageOffset;
 852         int created;
 853
 854         created = 0;
 855         pageOffset.HighPart = offsetp->HighPart;
 856         pageOffset.LowPart = offsetp->LowPart & ~(buf_bufferSize-1);
 857         while (1) {
 858                 lock_ObtainWrite(&buf_globalLock);
 859                 bp = buf_LockedFind(scp, &pageOffset);
 860                 lock_ReleaseWrite(&buf_globalLock);
 861                 if (bp) {
 862                         /* lock it and break out */
 863                         lock_ObtainMutex(&bp->mx);
 864                         break;
 865                 }
 866
 867                 /* otherwise, we have to create a page */
 868                 code = buf_GetNewLocked(scp, &pageOffset, &bp);
 869
 870                 /* check if the buffer was created in a race condition branch.
 871                  * If so, go around so we can hold a reference to it.
 872                  */
 873                 if (code == CM_BUF_EXISTS) continue;
 874
 875                 /* something else went wrong */
 876                 if (code != 0) return code;
 877
 878                 /* otherwise, we have a locked buffer that we just created */
 879                 created = 1;
 880                 break;
 881         } /* big while loop */
 882
 883         /* wait for reads */
 884         if (bp->flags & CM_BUF_READING)
 885                 buf_WaitIO(bp);
 886
 887         /* once it has been read once, we can unlock it and return it, still
 888          * with its refcount held.
 889          */
 890         lock_ReleaseMutex(&bp->mx);
 891         *bufpp = bp;
 892         osi_Log3(buf_logp, "buf_GetNew returning bp 0x%x for file 0x%x, offset 0x%x",
 893                 bp, (long) scp, offsetp->LowPart);
 894         return 0;
 895 }
 896
 897 /* get a page, returning it held but unlocked.  Make sure it is complete */
 898 long buf_Get(struct cm_scache *scp, osi_hyper_t *offsetp, cm_buf_t **bufpp)
 899 {
 900         cm_buf_t *bp;
 901         long code;
 902         osi_hyper_t pageOffset;
 903         unsigned long tcount;
 904         int created;
 905 #ifdef DISKCACHE95
 906         cm_diskcache_t *dcp;
 907 #endif /* DISKCACHE95 */
 908
 909         created = 0;
 910         pageOffset.HighPart = offsetp->HighPart;
 911         pageOffset.LowPart = offsetp->LowPart & ~(buf_bufferSize-1);
 912         while (1) {
 913                 lock_ObtainWrite(&buf_globalLock);
 914                 bp = buf_LockedFind(scp, &pageOffset);
 915                 lock_ReleaseWrite(&buf_globalLock);
 916                 if (bp) {
 917                         /* lock it and break out */
 918                         lock_ObtainMutex(&bp->mx);
 919                         break;
 920
 921 #ifdef DISKCACHE95
 922                         /* touch disk chunk to update LRU info */
 923                         diskcache_Touch(bp->dcp);
 924 #endif /* DISKCACHE95 */
 925                 }
 926
 927                 /* otherwise, we have to create a page */
 928                 code = buf_GetNewLocked(scp, &pageOffset, &bp);
 929
 930                 /* check if the buffer was created in a race condition branch.
 931                  * If so, go around so we can hold a reference to it.
 932                  */
 933                 if (code == CM_BUF_EXISTS) continue;
 934
 935                 /* something else went wrong */
 936                 if (code != 0) return code;
 937
 938                 /* otherwise, we have a locked buffer that we just created */
 939                 created = 1;
 940                 break;
 941         } /* big while loop */
 942
 943         /* if we get here, we have a locked buffer that may have just been
 944          * created, in which case it needs to be filled with data.
 945          */
 946         if (created) {
 947                 /* load the page; freshly created pages should be idle */
 948                 osi_assert(!(bp->flags & (CM_BUF_READING | CM_BUF_WRITING)));
 949
 950                 /* setup offset, event */
 951 #ifndef DJGPP  /* doesn't seem to be used */
 952                 bp->over.Offset = bp->offset.LowPart;
 953                 bp->over.OffsetHigh = bp->offset.HighPart;
 954 #endif /* !DJGPP */
 955
 956                 /* start the I/O; may drop lock */
 957                 bp->flags |= CM_BUF_READING;
 958                 code = (*cm_buf_opsp->Readp)(bp, buf_bufferSize, &tcount, NULL);
 959
 960 #ifdef DISKCACHE95
 961                 code = diskcache_Get(&bp->fid, &bp->offset, bp->datap, buf_bufferSize, &bp->dataVersion, &tcount, &dcp);
 962                 bp->dcp = dcp;    /* pointer to disk cache struct. */
 963 #endif /* DISKCACHE95 */
 964
 965                 if (code != 0) {
 966                         /* failure or queued */
 967 #ifndef DJGPP   /* cm_bufRead always returns 0 */
 968                         if (code != ERROR_IO_PENDING) {
 969 #endif
 970                                 bp->error = code;
 971                                 bp->flags |= CM_BUF_ERROR;
 972                                 bp->flags &= ~CM_BUF_READING;
 973                                 if (bp->flags & CM_BUF_WAITING) {
 974                                         bp->flags &= ~CM_BUF_WAITING;
 975                                         osi_Wakeup((long) bp);
 976                                 }
 977                                 lock_ReleaseMutex(&bp->mx);
 978                                 buf_Release(bp);
 979                                 return code;
 980 #ifndef DJGPP
 981                         }
 982 #endif
 983                 } else {
 984                         /* otherwise, I/O completed instantly and we're done, except
 985                          * for padding the xfr out with 0s and checking for EOF
 986                          */
 987                         if (tcount < (unsigned long) buf_bufferSize) {
 988                                 memset(bp->datap+tcount, 0, buf_bufferSize - tcount);
 989                                 if (tcount == 0)
 990                                         bp->flags |= CM_BUF_EOF;
 991                         }
 992                         bp->flags &= ~CM_BUF_READING;
 993                         if (bp->flags & CM_BUF_WAITING) {
 994                                 bp->flags &= ~CM_BUF_WAITING;
 995                                 osi_Wakeup((long) bp);
 996                         }
 997                 }
 998
 999         } /* if created */
1000
1001         /* wait for reads, either that which we started above, or that someone
1002          * else started.  We don't care if we return a buffer being cleaned.
1003          */
1004         if (bp->flags & CM_BUF_READING)
1005                 buf_WaitIO(bp);
1006
1007         /* once it has been read once, we can unlock it and return it, still
1008          * with its refcount held.
1009          */
1010         lock_ReleaseMutex(&bp->mx);
1011         *bufpp = bp;
1012
1013         /* now remove from queue; will be put in at the head (farthest from
1014          * being recycled) when we're done in buf_Release.
1015          */
1016         lock_ObtainWrite(&buf_globalLock);
1017         if (bp->flags & CM_BUF_INLRU) {
1018                 if (buf_freeListEndp == bp)
1019                         buf_freeListEndp = (cm_buf_t *) osi_QPrev(&bp->q);
1020                 osi_QRemove((osi_queue_t **) &buf_freeListp, &bp->q);
1021                 bp->flags &= ~CM_BUF_INLRU;
1022         }
1023         lock_ReleaseWrite(&buf_globalLock);
1024
1025         osi_Log3(buf_logp, "buf_Get returning bp 0x%x for file 0x%x, offset 0x%x",
1026                 bp, (long) scp, offsetp->LowPart);
1027         return 0;
1028 }
1029
1030 /* count # of elements in the free list;
1031  * we don't bother doing the proper locking for accessing dataVersion or flags
1032  * since it is a pain, and this is really just an advisory call.  If you need
1033  * to do better at some point, rewrite this function.
1034  */
1035 long buf_CountFreeList(void)
1036 {
1037         long count;
1038         cm_buf_t *bufp;
1039
1040         count = 0;
1041         lock_ObtainRead(&buf_globalLock);
1042         for(bufp = buf_freeListp; bufp; bufp = (cm_buf_t *) osi_QNext(&bufp->q)) {
1043                 /* if the buffer doesn't have an identity, or if the buffer
1044                  * has been invalidate (by having its DV stomped upon), then
1045                  * count it as free, since it isn't really being utilized.
1046                  */
1047                 if (!(bufp->flags & CM_BUF_INHASH) || bufp->dataVersion <= 0)
1048                         count++;
1049         }
1050         lock_ReleaseRead(&buf_globalLock);
1051         return count;
1052 }
1053
1054 /* clean a buffer synchronously */
1055 void buf_CleanAsync(cm_buf_t *bp, cm_req_t *reqp)
1056 {
1057         lock_ObtainMutex(&bp->mx);
1058         buf_LockedCleanAsync(bp, reqp);
1059         lock_ReleaseMutex(&bp->mx);
1060 }
1061
1062 /* wait for a buffer's cleaning to finish */
1063 void buf_CleanWait(cm_buf_t *bp)
1064 {
1065         lock_ObtainMutex(&bp->mx);
1066         if (bp->flags & CM_BUF_WRITING) {
1067                 buf_WaitIO(bp);
1068         }
1069         lock_ReleaseMutex(&bp->mx);
1070 }
1071
1072 /* set the dirty flag on a buffer, and set associated write-ahead log,
1073  * if there is one.  Allow one to be added to a buffer, but not changed.
1074  *
1075  * The buffer must be locked before calling this routine.
1076  */
1077 void buf_SetDirty(cm_buf_t *bp)
1078 {
1079         osi_assert(bp->refCount > 0);
1080
1081         osi_Log1(buf_logp, "buf_SetDirty 0x%x", bp);
1082
1083         /* set dirty bit */
1084         bp->flags |= CM_BUF_DIRTY;
1085
1086         /* and turn off EOF flag, since it has associated data now */
1087         bp->flags &= ~CM_BUF_EOF;
1088 }
1089
1090 /* clean all buffers, reset log pointers and invalidate all buffers.
1091  * Called with no locks held, and returns with same.
1092  *
1093  * This function is guaranteed to clean and remove the log ptr of all the
1094  * buffers that were dirty or had non-zero log ptrs before the call was
1095  * made.  That's sufficient to clean up any garbage left around by recovery,
1096  * which is all we're counting on this for; there may be newly created buffers
1097  * added while we're running, but that should be OK.
1098  *
1099  * In an environment where there are no transactions (artificially imposed, for
1100  * example, when switching the database to raw mode), this function is used to
1101  * make sure that all updates have been written to the disk.  In that case, we don't
1102  * really require that we forget the log association between pages and logs, but
1103  * it also doesn't hurt.  Since raw mode I/O goes through this buffer package, we don't
1104  * have to worry about invalidating data in the buffers.
1105  *
1106  * This function is used at the end of recovery as paranoia to get the recovered
1107  * database out to disk.  It removes all references to the recovery log and cleans
1108  * all buffers.
1109  */
1110 long buf_CleanAndReset(void)
1111 {
1112         long i;
1113         cm_buf_t *bp;
1114         cm_req_t req;
1115
1116         lock_ObtainWrite(&buf_globalLock);
1117         for(i=0; i<buf_hashSize; i++) {
1118                 for(bp = buf_hashTablepp[i]; bp; bp = bp->hashp) {
1119                         bp->refCount++;
1120                         lock_ReleaseWrite(&buf_globalLock);
1121
1122                         /* now no locks are held; clean buffer and go on */
1123                         cm_InitReq(&req);
1124                         buf_CleanAsync(bp, &req);
1125                         buf_CleanWait(bp);
1126
1127                         /* relock and release buffer */
1128                         lock_ObtainWrite(&buf_globalLock);
1129                         buf_LockedRelease(bp);
1130                 } /* over one bucket */
1131         }       /* for loop over all hash buckets */
1132
1133         /* release locks */
1134         lock_ReleaseWrite(&buf_globalLock);
1135
1136         /* and we're done */
1137         return 0;
1138 }
1139
1140 /* called without global lock being held, reserves buffers for callers
1141  * that need more than one held (not locked) at once.
1142  */
1143 void buf_ReserveBuffers(long nbuffers)
1144 {
1145         lock_ObtainWrite(&buf_globalLock);
1146         while (1) {
1147                 if (buf_reservedBufs + nbuffers > buf_maxReservedBufs) {
1148                         buf_reserveWaiting = 1;
1149                         osi_Log1(buf_logp, "buf_ReserveBuffers waiting for %d bufs", nbuffers);
1150                         osi_SleepW((long) &buf_reservedBufs, &buf_globalLock);
1151                         lock_ObtainWrite(&buf_globalLock);
1152                 }
1153                 else {
1154                         buf_reservedBufs += nbuffers;
1155                         break;
1156                 }
1157         }
1158         lock_ReleaseWrite(&buf_globalLock);
1159 }
1160
1161 int buf_TryReserveBuffers(long nbuffers)
1162 {
1163         int code;
1164
1165         lock_ObtainWrite(&buf_globalLock);
1166         if (buf_reservedBufs + nbuffers > buf_maxReservedBufs) {
1167                 code = 0;
1168         }
1169         else {
1170                 buf_reservedBufs += nbuffers;
1171                 code = 1;
1172         }
1173         lock_ReleaseWrite(&buf_globalLock);
1174         return code;
1175 }
1176
1177 /* called without global lock held, releases reservation held by
1178  * buf_ReserveBuffers.
1179  */
1180 void buf_UnreserveBuffers(long nbuffers)
1181 {
1182         lock_ObtainWrite(&buf_globalLock);
1183         buf_reservedBufs -= nbuffers;
1184         if (buf_reserveWaiting) {
1185                 buf_reserveWaiting = 0;
1186                 osi_Wakeup((long) &buf_reservedBufs);
1187         }
1188         lock_ReleaseWrite(&buf_globalLock);
1189 }
1190
1191 /* truncate the buffers past sizep, zeroing out the page, if we don't
1192  * end on a page boundary.
1193  *
1194  * Requires cm_bufCreateLock to be write locked.
1195  */
1196 long buf_Truncate(cm_scache_t *scp, cm_user_t *userp, cm_req_t *reqp,
1197         osi_hyper_t *sizep)
1198 {
1199         cm_buf_t *bufp;
1200         cm_buf_t *nbufp;                        /* next buffer, if didRelease */
1201         osi_hyper_t bufEnd;
1202         long code;
1203         long bufferPos;
1204         int didRelease;
1205         long i;
1206
1207         /* assert that cm_bufCreateLock is held in write mode */
1208         lock_AssertWrite(&scp->bufCreateLock);
1209
1210         i = BUF_FILEHASH(&scp->fid);
1211
1212         lock_ObtainWrite(&buf_globalLock);
1213         bufp = buf_fileHashTablepp[i];
1214         if (bufp == NULL) {
1215                 lock_ReleaseWrite(&buf_globalLock);
1216                 return 0;
1217         }
1218
1219         bufp->refCount++;
1220         lock_ReleaseWrite(&buf_globalLock);
1221         for(; bufp; bufp = nbufp) {
1222                 didRelease = 0;
1223                 lock_ObtainMutex(&bufp->mx);
1224
1225                 bufEnd.HighPart = 0;
1226                 bufEnd.LowPart = buf_bufferSize;
1227                 bufEnd = LargeIntegerAdd(bufEnd, bufp->offset);
1228
1229                 if (cm_FidCmp(&bufp->fid, &scp->fid) == 0 &&
1230                         LargeIntegerLessThan(*sizep, bufEnd)) {
1231                         buf_WaitIO(bufp);
1232                 }
1233                 lock_ObtainMutex(&scp->mx);
1234
1235                 /* make sure we have a callback (so we have the right value for
1236                  * the length), and wait for it to be safe to do a truncate.
1237                  */
1238                 code = cm_SyncOp(scp, bufp, userp, reqp, 0,
1239                                  CM_SCACHESYNC_NEEDCALLBACK
1240                                  | CM_SCACHESYNC_GETSTATUS
1241                                  | CM_SCACHESYNC_SETSIZE
1242                                  | CM_SCACHESYNC_BUFLOCKED);
1243                 /* if we succeeded in our locking, and this applies to the right
1244                  * file, and the truncate request overlaps the buffer either
1245                  * totally or partially, then do something.
1246                  */
1247                 if (code == 0 && cm_FidCmp(&bufp->fid, &scp->fid) == 0
1248                         && LargeIntegerLessThan(*sizep, bufEnd)) {
1249
1250                         lock_ObtainWrite(&buf_globalLock);
1251
1252                         /* destroy the buffer, turning off its dirty bit, if
1253                          * we're truncating the whole buffer.  Otherwise, set
1254                          * the dirty bit, and clear out the tail of the buffer
1255                          * if we just overlap some.
1256                          */
1257                         if (LargeIntegerLessThanOrEqualTo(*sizep, bufp->offset)) {
1258                                 /* truncating the entire page */
1259                                 bufp->flags &= ~CM_BUF_DIRTY;
1260                                 bufp->dataVersion = -1; /* known bad */
1261                                 bufp->dirtyCounter++;
1262                         }
1263                         else {
1264                                 /* don't set dirty, since dirty implies
1265                                  * currently up-to-date.  Don't need to do this,
1266                                  * since we'll update the length anyway.
1267                                  *
1268                                  * Zero out remainder of the page, in case we
1269                                  * seek and write past EOF, and make this data
1270                                  * visible again.
1271                                  */
1272                                 bufferPos = sizep->LowPart & (buf_bufferSize - 1);
1273                                 osi_assert(bufferPos != 0);
1274                                 memset(bufp->datap + bufferPos, 0,
1275                                         buf_bufferSize - bufferPos);
1276                         }
1277
1278                         lock_ReleaseWrite(&buf_globalLock);
1279
1280                 }
1281
1282                 lock_ReleaseMutex(&scp->mx);
1283                 lock_ReleaseMutex(&bufp->mx);
1284                 if (!didRelease) {
1285                         lock_ObtainWrite(&buf_globalLock);
1286                         nbufp = bufp->fileHashp;
1287                         if (nbufp) nbufp->refCount++;
1288                         buf_LockedRelease(bufp);
1289                         lock_ReleaseWrite(&buf_globalLock);
1290                 }
1291
1292                 /* bail out early if we fail */
1293                 if (code) {
1294                         /* at this point, nbufp is held; bufp has already been
1295                          * released.
1296                          */
1297                         if (nbufp) buf_Release(nbufp);
1298                         return code;
1299                 }
1300         }
1301
1302         /* success */
1303         return 0;
1304 }
1305
1306 long buf_FlushCleanPages(cm_scache_t *scp, cm_user_t *userp, cm_req_t *reqp)
1307 {
1308         long code;
1309         cm_buf_t *bp;           /* buffer we're hacking on */
1310         cm_buf_t *nbp;
1311         int didRelease;
1312         long i;
1313
1314         i = BUF_FILEHASH(&scp->fid);
1315
1316         code = 0;
1317         lock_ObtainWrite(&buf_globalLock);
1318         bp = buf_fileHashTablepp[i];
1319         if (bp) bp->refCount++;
1320         lock_ReleaseWrite(&buf_globalLock);
1321         for(; bp; bp = nbp) {
1322                 didRelease = 0; /* haven't released this buffer yet */
1323
1324                 /* clean buffer synchronously */
1325                 if (cm_FidCmp(&bp->fid, &scp->fid) == 0) {
1326                         lock_ObtainMutex(&bp->mx);
1327
1328                         /* start cleaning the buffer, and wait for it to finish */
1329                         buf_LockedCleanAsync(bp, reqp);
1330                         buf_WaitIO(bp);
1331                         lock_ReleaseMutex(&bp->mx);
1332
1333                         code = (*cm_buf_opsp->Stabilizep)(scp, userp, reqp);
1334                         if (code) goto skip;
1335
1336                         lock_ObtainWrite(&buf_globalLock);
1337                         /* actually, we only know that buffer is clean if ref
1338                          * count is 1, since we don't have buffer itself locked.
1339                          */
1340                         if (!(bp->flags & CM_BUF_DIRTY)) {
1341                                 if (bp->refCount == 1) {        /* bp is held above */
1342                                         buf_LockedRelease(bp);
1343                                         nbp = bp->fileHashp;
1344                                         if (nbp) nbp->refCount++;
1345                                         didRelease = 1;
1346                                         buf_Recycle(bp);
1347                                 }
1348                         }
1349                         lock_ReleaseWrite(&buf_globalLock);
1350
1351                         (*cm_buf_opsp->Unstabilizep)(scp, userp);
1352                 }
1353
1354 skip:
1355                 if (!didRelease) {
1356                         lock_ObtainWrite(&buf_globalLock);
1357                         if (nbp = bp->fileHashp) nbp->refCount++;
1358                         buf_LockedRelease(bp);
1359                         lock_ReleaseWrite(&buf_globalLock);
1360                 }
1361         }       /* for loop over a bunch of buffers */
1362
1363         /* done */
1364         return code;
1365 }
1366
1367 long buf_CleanVnode(struct cm_scache *scp, cm_user_t *userp, cm_req_t *reqp)
1368 {
1369         long code;
1370         cm_buf_t *bp;           /* buffer we're hacking on */
1371         cm_buf_t *nbp;          /* next one */
1372         long i;
1373
1374         i = BUF_FILEHASH(&scp->fid);
1375
1376         code = 0;
1377         lock_ObtainWrite(&buf_globalLock);
1378         bp = buf_fileHashTablepp[i];
1379         if (bp) bp->refCount++;
1380         lock_ReleaseWrite(&buf_globalLock);
1381         for(; bp; bp = nbp) {
1382                 /* clean buffer synchronously */
1383                 if (cm_FidCmp(&bp->fid, &scp->fid) == 0) {
1384                         if (userp) {
1385                                 lock_ObtainMutex(&bp->mx);
1386                                 if (bp->userp) cm_ReleaseUser(bp->userp);
1387                                 bp->userp = userp;
1388                                 lock_ReleaseMutex(&bp->mx);
1389                                 cm_HoldUser(userp);
1390                         }
1391                         buf_CleanAsync(bp, reqp);
1392                         buf_CleanWait(bp);
1393                         lock_ObtainMutex(&bp->mx);
1394                         if (bp->flags & CM_BUF_ERROR) {
1395                                 if (code == 0 || code == -1) code = bp->error;
1396                                 if (code == 0) code = -1;
1397                         }
1398                         lock_ReleaseMutex(&bp->mx);
1399                 }
1400
1401                 lock_ObtainWrite(&buf_globalLock);
1402                 buf_LockedRelease(bp);
1403                 nbp = bp->fileHashp;
1404                 if (nbp) nbp->refCount++;
1405                 lock_ReleaseWrite(&buf_globalLock);
1406         }       /* for loop over a bunch of buffers */
1407
1408         /* done */
1409         return code;
1410 }
1411
1412 /* dump the contents of the buf_hashTablepp. */
1413 int cm_DumpBufHashTable(FILE *outputFile, char *cookie)
1414 {
1415     int zilch;
1416     cm_buf_t *bp;
1417     char output[1024];
1418     int i;
1419
1420     lock_ObtainRead(&buf_globalLock);
1421
1422     sprintf(output, "%s - dumping buf_HashTable - buf_hashSize=%d\n", cookie, buf_hashSize);
1423     WriteFile(outputFile, output, strlen(output), &zilch, NULL);
1424
1425     for (i = 0; i < buf_hashSize; i++)
1426     {
1427         for(bp = buf_hashTablepp[i]; bp; bp=bp->hashp)
1428         {
1429             if (bp->refCount)
1430             {
1431                 sprintf(output, "%s bp=0x%08X, hash=%d, fid (cell=%d, volume=%d,"
1432                         "vnode=%d, unique=%d), size=%d refCount=%d\n",
1433                         cookie, (void *)bp, i, bp->fid.cell, bp->fid.volume,
1434                         bp->fid.vnode, bp->fid.unique, bp->size, bp->refCount);
1435                 WriteFile(outputFile, output, strlen(output), &zilch, NULL);
1436             }
1437         }
1438     }
1439
1440     sprintf(output, "%s - Done dumping buf_HashTable.\n", cookie);
1441     WriteFile(outputFile, output, strlen(output), &zilch, NULL);
1442
1443     lock_ReleaseRead(&buf_globalLock);
1444 }
1445