reactos/ntoskrnl/cc/view.c

/*
 * COPYRIGHT:       See COPYING in the top level directory
 * PROJECT:         ReactOS kernel
 * FILE:            ntoskrnl/cc/view.c
 * PURPOSE:         Cache manager
 *
 * PROGRAMMERS:     David Welch (welch@mcmail.com)
 */

/* NOTES **********************************************************************
 *
 * This is not the NT implementation of a file cache nor anything much like
 * it.
 *
 * The general procedure for a filesystem to implement a read or write
 * dispatch routine is as follows
 *
 * (1) If caching for the FCB hasn't been initiated then so do by calling
 * CcInitializeFileCache.
 *
 * (2) For each 4k region which is being read or written obtain a cache page
 * by calling CcRequestCachePage.
 *
 * (3) If either the page is being read or not completely written, and it is
 * not up to date then read its data from the underlying medium. If the read
 * fails then call CcReleaseCachePage with VALID as FALSE and return a error.
 *
 * (4) Copy the data into or out of the page as necessary.
 *
 * (5) Release the cache page
 */
/* INCLUDES ******************************************************************/

#include <ntoskrnl.h>
#define NDEBUG
#include <debug.h>

#if defined (ALLOC_PRAGMA)
#pragma alloc_text(INIT, CcInitView)
#endif

/* GLOBALS *******************************************************************/

/*
 * If CACHE_BITMAP is defined, the cache manager uses one large memory region
 * within the kernel address space and allocate/deallocate space from this block
 * over a bitmap. If CACHE_BITMAP is used, the size of the mdl mapping region
 * must be reduced (ntoskrnl\mm\mdl.c, MI_MDLMAPPING_REGION_SIZE).
 */
//#define CACHE_BITMAP

static LIST_ENTRY DirtySegmentListHead;
static LIST_ENTRY CacheSegmentListHead;
static LIST_ENTRY CacheSegmentLRUListHead;
static LIST_ENTRY ClosedListHead;
ULONG DirtyPageCount=0;

KGUARDED_MUTEX ViewLock;

#ifdef CACHE_BITMAP
#define	CI_CACHESEG_MAPPING_REGION_SIZE	(128*1024*1024)

static PVOID CiCacheSegMappingRegionBase = NULL;
static RTL_BITMAP CiCacheSegMappingRegionAllocMap;
static ULONG CiCacheSegMappingRegionHint;
static KSPIN_LOCK CiCacheSegMappingRegionLock;
#endif

NPAGED_LOOKASIDE_LIST iBcbLookasideList;
static NPAGED_LOOKASIDE_LIST BcbLookasideList;
static NPAGED_LOOKASIDE_LIST CacheSegLookasideList;

#if DBG
static void CcRosCacheSegmentIncRefCount_ ( PCACHE_SEGMENT cs, const char* file, int line )
{
	++cs->ReferenceCount;
	if ( cs->Bcb->Trace )
	{
		DbgPrint("(%s:%i) CacheSegment %p ++RefCount=%d, Dirty %d, PageOut %d\n",
			file, line, cs, cs->ReferenceCount, cs->Dirty, cs->PageOut );
	}
}
static void CcRosCacheSegmentDecRefCount_ ( PCACHE_SEGMENT cs, const char* file, int line )
{
	--cs->ReferenceCount;
	if ( cs->Bcb->Trace )
	{
		DbgPrint("(%s:%i) CacheSegment %p --RefCount=%d, Dirty %d, PageOut %d\n",
			file, line, cs, cs->ReferenceCount, cs->Dirty, cs->PageOut );
	}
}
#define CcRosCacheSegmentIncRefCount(cs) CcRosCacheSegmentIncRefCount_(cs,__FILE__,__LINE__)
#define CcRosCacheSegmentDecRefCount(cs) CcRosCacheSegmentDecRefCount_(cs,__FILE__,__LINE__)
#else
#define CcRosCacheSegmentIncRefCount(cs) (++((cs)->ReferenceCount))
#define CcRosCacheSegmentDecRefCount(cs) (--((cs)->ReferenceCount))
#endif

NTSTATUS
CcRosInternalFreeCacheSegment(PCACHE_SEGMENT CacheSeg);


/* FUNCTIONS *****************************************************************/

VOID
NTAPI
CcRosTraceCacheMap (
	PBCB Bcb,
	BOOLEAN Trace )
{
#if DBG
	KIRQL oldirql;
	PLIST_ENTRY current_entry;
	PCACHE_SEGMENT current;

	if ( !Bcb )
		return;

	Bcb->Trace = Trace;

	if ( Trace )
	{
		DPRINT1("Enabling Tracing for CacheMap 0x%p:\n", Bcb );

		KeAcquireGuardedMutex(&ViewLock);
		KeAcquireSpinLock(&Bcb->BcbLock, &oldirql);

		current_entry = Bcb->BcbSegmentListHead.Flink;
		while (current_entry != &Bcb->BcbSegmentListHead)
		{
			current = CONTAINING_RECORD(current_entry, CACHE_SEGMENT, BcbSegmentListEntry);
			current_entry = current_entry->Flink;

			DPRINT1("  CacheSegment 0x%p enabled, RefCount %d, Dirty %d, PageOut %d\n",
				current, current->ReferenceCount, current->Dirty, current->PageOut );
		}
		KeReleaseSpinLock(&Bcb->BcbLock, oldirql);
		KeReleaseGuardedMutex(&ViewLock);
	}
	else
	{
		DPRINT1("Disabling Tracing for CacheMap 0x%p:\n", Bcb );
	}

#else
	Bcb = Bcb;
	Trace = Trace;
#endif
}

NTSTATUS
NTAPI
CcRosFlushCacheSegment(PCACHE_SEGMENT CacheSegment)
{
    NTSTATUS Status;
    KIRQL oldIrql;
    
    Status = WriteCacheSegment(CacheSegment);
    if (NT_SUCCESS(Status))
    {
        KeAcquireGuardedMutex(&ViewLock);
        KeAcquireSpinLock(&CacheSegment->Bcb->BcbLock, &oldIrql);
        
        CacheSegment->Dirty = FALSE;
        RemoveEntryList(&CacheSegment->DirtySegmentListEntry);
        DirtyPageCount -= CacheSegment->Bcb->CacheSegmentSize / PAGE_SIZE;
        CcRosCacheSegmentDecRefCount ( CacheSegment );
        
        KeReleaseSpinLock(&CacheSegment->Bcb->BcbLock, oldIrql);
        KeReleaseGuardedMutex(&ViewLock);
    }
    
    return(Status);
}

NTSTATUS
NTAPI
CcRosFlushDirtyPages(ULONG Target, PULONG Count, BOOLEAN Wait)
{
    PLIST_ENTRY current_entry;
    PCACHE_SEGMENT current;
    ULONG PagesPerSegment;
    BOOLEAN Locked;
    NTSTATUS Status;
    LARGE_INTEGER ZeroTimeout;
    
    DPRINT("CcRosFlushDirtyPages(Target %d)\n", Target);
    
    (*Count) = 0;
    ZeroTimeout.QuadPart = 0;
    
    KeEnterCriticalRegion();
    KeAcquireGuardedMutex(&ViewLock);
    
    current_entry = DirtySegmentListHead.Flink;
    if (current_entry == &DirtySegmentListHead)
    {
        DPRINT("No Dirty pages\n");
    }
    
    while (current_entry != &DirtySegmentListHead && Target > 0)
    {
        current = CONTAINING_RECORD(current_entry, CACHE_SEGMENT,
                                    DirtySegmentListEntry);
        current_entry = current_entry->Flink;

        CcRosCacheSegmentIncRefCount(current);

        Locked = current->Bcb->Callbacks->AcquireForLazyWrite(
            current->Bcb->LazyWriteContext, Wait);
        if (!Locked)
        {
            CcRosCacheSegmentDecRefCount(current);
            continue;
        }

        Status = KeWaitForSingleObject(&current->Mutex,
                                       Executive,
                                       KernelMode,
                                       FALSE,
                                       Wait ? NULL : &ZeroTimeout);
        if (Status != STATUS_SUCCESS)
        {
            current->Bcb->Callbacks->ReleaseFromLazyWrite(
                current->Bcb->LazyWriteContext);
            CcRosCacheSegmentDecRefCount(current);
            continue;
        }

        ASSERT(current->Dirty);

        /* One reference is added above */
        if (current->ReferenceCount > 2)
        {
            KeReleaseMutex(&current->Mutex, 0);
            current->Bcb->Callbacks->ReleaseFromLazyWrite(
                current->Bcb->LazyWriteContext);
            CcRosCacheSegmentDecRefCount(current);
            continue;
        }

        PagesPerSegment = current->Bcb->CacheSegmentSize / PAGE_SIZE;

        KeReleaseGuardedMutex(&ViewLock);

        Status = CcRosFlushCacheSegment(current);

        KeReleaseMutex(&current->Mutex, 0);
        current->Bcb->Callbacks->ReleaseFromLazyWrite(
            current->Bcb->LazyWriteContext);
        
        KeAcquireGuardedMutex(&ViewLock);
        CcRosCacheSegmentDecRefCount(current);

        if (!NT_SUCCESS(Status) &&  (Status != STATUS_END_OF_FILE))
        {
            DPRINT1("CC: Failed to flush cache segment.\n");
        }
        else
        {
            (*Count) += PagesPerSegment;
            Target -= PagesPerSegment;
        }

        current_entry = DirtySegmentListHead.Flink;
    }
    
    KeReleaseGuardedMutex(&ViewLock);
    KeLeaveCriticalRegion();
    
    DPRINT("CcRosFlushDirtyPages() finished\n");
    return(STATUS_SUCCESS);
}

NTSTATUS
CcRosTrimCache(ULONG Target, ULONG Priority, PULONG NrFreed)
/*
 * FUNCTION: Try to free some memory from the file cache.
 * ARGUMENTS:
 *       Target - The number of pages to be freed.
 *       Priority - The priority of free (currently unused).
 *       NrFreed - Points to a variable where the number of pages
 *                 actually freed is returned.
 */
{
    PLIST_ENTRY current_entry;
    PCACHE_SEGMENT current;
    ULONG PagesPerSegment;
    ULONG PagesFreed;
    KIRQL oldIrql;
    LIST_ENTRY FreeList;
    PFN_NUMBER Page;
    ULONG i;
    BOOLEAN FlushedPages = FALSE;

    DPRINT("CcRosTrimCache(Target %d)\n", Target);

    InitializeListHead(&FreeList);

    *NrFreed = 0;

retry:
    KeAcquireGuardedMutex(&ViewLock);

    current_entry = CacheSegmentLRUListHead.Flink;
    while (current_entry != &CacheSegmentLRUListHead)
    {
        current = CONTAINING_RECORD(current_entry, CACHE_SEGMENT,
                                    CacheSegmentLRUListEntry);
        current_entry = current_entry->Flink;

        KeAcquireSpinLock(&current->Bcb->BcbLock, &oldIrql);

        /* Reference the cache segment */
        CcRosCacheSegmentIncRefCount(current);

        /* Check if it's mapped and not dirty */
        if (current->MappedCount > 0 && !current->Dirty)
        {
            /* We have to break these locks because Cc sucks */
            KeReleaseSpinLock(&current->Bcb->BcbLock, oldIrql);
            KeReleaseGuardedMutex(&ViewLock);

            /* Page out the segment */
            for (i = 0; i < current->Bcb->CacheSegmentSize / PAGE_SIZE; i++)
            {
                Page = (PFN_NUMBER)(MmGetPhysicalAddress((PUCHAR)current->BaseAddress + (i * PAGE_SIZE)).QuadPart >> PAGE_SHIFT);

                MmPageOutPhysicalAddress(Page);
            }

            /* Reacquire the locks */
            KeAcquireGuardedMutex(&ViewLock);
            KeAcquireSpinLock(&current->Bcb->BcbLock, &oldIrql);
        }

        /* Dereference the cache segment */
        CcRosCacheSegmentDecRefCount(current);

        /* Check if we can free this entry now */
        if (current->ReferenceCount == 0)
        {
            ASSERT(!current->Dirty);
            ASSERT(!current->MappedCount);

            RemoveEntryList(&current->BcbSegmentListEntry);
            RemoveEntryList(&current->CacheSegmentListEntry);
            RemoveEntryList(&current->CacheSegmentLRUListEntry);
            InsertHeadList(&FreeList, &current->BcbSegmentListEntry);

            /* Calculate how many pages we freed for Mm */
            PagesPerSegment = current->Bcb->CacheSegmentSize / PAGE_SIZE;
            PagesFreed = min(PagesPerSegment, Target);
            Target -= PagesFreed;
            (*NrFreed) += PagesFreed;
        }

        KeReleaseSpinLock(&current->Bcb->BcbLock, oldIrql);
    }

    KeReleaseGuardedMutex(&ViewLock);

    /* Try flushing pages if we haven't met our target */
    if (Target > 0 && !FlushedPages)
    {
        /* Flush dirty pages to disk */
        CcRosFlushDirtyPages(Target, &PagesFreed, FALSE);
        FlushedPages = TRUE;

        /* We can only swap as many pages as we flushed */
        if (PagesFreed < Target) Target = PagesFreed;

        /* Check if we flushed anything */
        if (PagesFreed != 0)
        {
            /* Try again after flushing dirty pages */
            DPRINT("Flushed %d dirty cache pages to disk\n", PagesFreed);
            goto retry;
        }
    }

    while (!IsListEmpty(&FreeList))
    {
        current_entry = RemoveHeadList(&FreeList);
        current = CONTAINING_RECORD(current_entry, CACHE_SEGMENT,
                                    BcbSegmentListEntry);
        CcRosInternalFreeCacheSegment(current);
    }

    DPRINT("Evicted %d cache pages\n", (*NrFreed));

    return(STATUS_SUCCESS);
}

NTSTATUS
NTAPI
CcRosReleaseCacheSegment(PBCB Bcb,
			 PCACHE_SEGMENT CacheSeg,
			 BOOLEAN Valid,
			 BOOLEAN Dirty,
			 BOOLEAN Mapped)
{
  BOOLEAN WasDirty;
  KIRQL oldIrql;

  ASSERT(Bcb);

  DPRINT("CcReleaseCacheSegment(Bcb 0x%p, CacheSeg 0x%p, Valid %d)\n",
	 Bcb, CacheSeg, Valid);

  KeAcquireGuardedMutex(&ViewLock);
  KeAcquireSpinLock(&Bcb->BcbLock, &oldIrql);

  CacheSeg->Valid = Valid;

  WasDirty = CacheSeg->Dirty;
  CacheSeg->Dirty = CacheSeg->Dirty || Dirty;

  if (!WasDirty && CacheSeg->Dirty)
    {
      InsertTailList(&DirtySegmentListHead, &CacheSeg->DirtySegmentListEntry);
      DirtyPageCount += Bcb->CacheSegmentSize / PAGE_SIZE;
    }

  if (Mapped)
  {
     CacheSeg->MappedCount++;
  }
  CcRosCacheSegmentDecRefCount(CacheSeg);
  if (Mapped && CacheSeg->MappedCount == 1)
  {
      CcRosCacheSegmentIncRefCount(CacheSeg);
  }
  if (!WasDirty && CacheSeg->Dirty)
  {
      CcRosCacheSegmentIncRefCount(CacheSeg);
  }

  KeReleaseSpinLock(&Bcb->BcbLock, oldIrql);
  KeReleaseGuardedMutex(&ViewLock);
  KeReleaseMutex(&CacheSeg->Mutex, 0);

  return(STATUS_SUCCESS);
}

/* Returns with Cache Segment Lock Held! */
PCACHE_SEGMENT
NTAPI
CcRosLookupCacheSegment(PBCB Bcb, ULONG FileOffset)
{
    PLIST_ENTRY current_entry;
    PCACHE_SEGMENT current;
    KIRQL oldIrql;
    
    ASSERT(Bcb);
    
    DPRINT("CcRosLookupCacheSegment(Bcb -x%p, FileOffset %d)\n", Bcb, FileOffset);

    KeAcquireGuardedMutex(&ViewLock);
    KeAcquireSpinLock(&Bcb->BcbLock, &oldIrql);

    current_entry = Bcb->BcbSegmentListHead.Flink;
    while (current_entry != &Bcb->BcbSegmentListHead)
    {
        current = CONTAINING_RECORD(current_entry, CACHE_SEGMENT,
                                    BcbSegmentListEntry);
        if (current->FileOffset <= FileOffset &&
            (current->FileOffset + Bcb->CacheSegmentSize) > FileOffset)
        {
            CcRosCacheSegmentIncRefCount(current);
            KeReleaseSpinLock(&Bcb->BcbLock, oldIrql);
            KeReleaseGuardedMutex(&ViewLock);
            KeWaitForSingleObject(&current->Mutex,
                                  Executive,
                                  KernelMode,
                                  FALSE,
                                  NULL);
            return(current);
        }
        current_entry = current_entry->Flink;
    }

    KeReleaseSpinLock(&Bcb->BcbLock, oldIrql);
    KeReleaseGuardedMutex(&ViewLock);

    return(NULL);
}

NTSTATUS
NTAPI
CcRosMarkDirtyCacheSegment(PBCB Bcb, ULONG FileOffset)
{
  PCACHE_SEGMENT CacheSeg;
  KIRQL oldIrql;

  ASSERT(Bcb);

  DPRINT("CcRosMarkDirtyCacheSegment(Bcb 0x%p, FileOffset %d)\n", Bcb, FileOffset);

  CacheSeg = CcRosLookupCacheSegment(Bcb, FileOffset);
  if (CacheSeg == NULL)
    {
      KeBugCheck(CACHE_MANAGER);
    }

  KeAcquireGuardedMutex(&ViewLock);
  KeAcquireSpinLock(&Bcb->BcbLock, &oldIrql);

  if (!CacheSeg->Dirty)
  {
      InsertTailList(&DirtySegmentListHead, &CacheSeg->DirtySegmentListEntry);
      DirtyPageCount += Bcb->CacheSegmentSize / PAGE_SIZE;
  }
  else
  {
      CcRosCacheSegmentDecRefCount(CacheSeg);
  }

  /* Move to the tail of the LRU list */
  RemoveEntryList(&CacheSeg->CacheSegmentLRUListEntry);
  InsertTailList(&CacheSegmentLRUListHead, &CacheSeg->CacheSegmentLRUListEntry);

  CacheSeg->Dirty = TRUE;

  KeReleaseSpinLock(&Bcb->BcbLock, oldIrql);
  KeReleaseGuardedMutex(&ViewLock);
  KeReleaseMutex(&CacheSeg->Mutex, 0);

  return(STATUS_SUCCESS);
}

NTSTATUS
NTAPI
CcRosUnmapCacheSegment(PBCB Bcb, ULONG FileOffset, BOOLEAN NowDirty)
{
  PCACHE_SEGMENT CacheSeg;
  BOOLEAN WasDirty;
  KIRQL oldIrql;

  ASSERT(Bcb);

  DPRINT("CcRosUnmapCacheSegment(Bcb 0x%p, FileOffset %d, NowDirty %d)\n",
          Bcb, FileOffset, NowDirty);

  CacheSeg = CcRosLookupCacheSegment(Bcb, FileOffset);
  if (CacheSeg == NULL)
    {
      return(STATUS_UNSUCCESSFUL);
    }

  KeAcquireGuardedMutex(&ViewLock);
  KeAcquireSpinLock(&Bcb->BcbLock, &oldIrql);

  WasDirty = CacheSeg->Dirty;
  CacheSeg->Dirty = CacheSeg->Dirty || NowDirty;

  CacheSeg->MappedCount--;

  if (!WasDirty && NowDirty)
  {
     InsertTailList(&DirtySegmentListHead, &CacheSeg->DirtySegmentListEntry);
     DirtyPageCount += Bcb->CacheSegmentSize / PAGE_SIZE;
  }

  CcRosCacheSegmentDecRefCount(CacheSeg);
  if (!WasDirty && NowDirty)
  {
     CcRosCacheSegmentIncRefCount(CacheSeg);
  }
  if (CacheSeg->MappedCount == 0)
  {
     CcRosCacheSegmentDecRefCount(CacheSeg);
  }

  KeReleaseSpinLock(&Bcb->BcbLock, oldIrql);
  KeReleaseGuardedMutex(&ViewLock);
  KeReleaseMutex(&CacheSeg->Mutex, 0);

  return(STATUS_SUCCESS);
}

static
NTSTATUS
CcRosCreateCacheSegment(PBCB Bcb,
			ULONG FileOffset,
			PCACHE_SEGMENT* CacheSeg)
{
  PCACHE_SEGMENT current;
  PCACHE_SEGMENT previous;
  PLIST_ENTRY current_entry;
  NTSTATUS Status;
  KIRQL oldIrql;
#ifdef CACHE_BITMAP
  ULONG StartingOffset;
#endif
  PHYSICAL_ADDRESS BoundaryAddressMultiple;

  ASSERT(Bcb);

  DPRINT("CcRosCreateCacheSegment()\n");

  BoundaryAddressMultiple.QuadPart = 0;
  if (FileOffset >= Bcb->FileSize.u.LowPart)
  {
     CacheSeg = NULL;
     return STATUS_INVALID_PARAMETER;
  }

  current = ExAllocateFromNPagedLookasideList(&CacheSegLookasideList);
  current->Valid = FALSE;
  current->Dirty = FALSE;
  current->PageOut = FALSE;
  current->FileOffset = ROUND_DOWN(FileOffset, Bcb->CacheSegmentSize);
  current->Bcb = Bcb;
#if DBG
  if ( Bcb->Trace )
  {
    DPRINT1("CacheMap 0x%p: new Cache Segment: 0x%p\n", Bcb, current );
  }
#endif
  current->MappedCount = 0;
  current->DirtySegmentListEntry.Flink = NULL;
  current->DirtySegmentListEntry.Blink = NULL;
  current->ReferenceCount = 1;
  KeInitializeMutex(&current->Mutex, 0);
  KeWaitForSingleObject(&current->Mutex,
                        Executive,
                        KernelMode,
                        FALSE,
                        NULL);
  KeAcquireGuardedMutex(&ViewLock);

  *CacheSeg = current;
  /* There is window between the call to CcRosLookupCacheSegment
   * and CcRosCreateCacheSegment. We must check if a segment on
   * the fileoffset exist. If there exist a segment, we release
   * our new created segment and return the existing one.
   */
  KeAcquireSpinLock(&Bcb->BcbLock, &oldIrql);
  current_entry = Bcb->BcbSegmentListHead.Flink;
  previous = NULL;
  while (current_entry != &Bcb->BcbSegmentListHead)
  {
     current = CONTAINING_RECORD(current_entry, CACHE_SEGMENT,
				 BcbSegmentListEntry);
     if (current->FileOffset <= FileOffset &&
      	(current->FileOffset + Bcb->CacheSegmentSize) > FileOffset)
     {
	CcRosCacheSegmentIncRefCount(current);
	KeReleaseSpinLock(&Bcb->BcbLock, oldIrql);
#if DBG
	if ( Bcb->Trace )
	{
		DPRINT1("CacheMap 0x%p: deleting newly created Cache Segment 0x%p ( found existing one 0x%p )\n",
			Bcb,
			(*CacheSeg),
			current );
	}
#endif
	KeReleaseMutex(&(*CacheSeg)->Mutex, 0);
	KeReleaseGuardedMutex(&ViewLock);
	ExFreeToNPagedLookasideList(&CacheSegLookasideList, *CacheSeg);
	*CacheSeg = current;
    KeWaitForSingleObject(&current->Mutex,
                          Executive,
                          KernelMode,
                          FALSE,
                          NULL);
	return STATUS_SUCCESS;
     }
     if (current->FileOffset < FileOffset)
     {
        if (previous == NULL)
	{
	   previous = current;
	}
	else
	{
	   if (previous->FileOffset < current->FileOffset)
	   {
	      previous = current;
	   }
	}
     }
     current_entry = current_entry->Flink;
  }
  /* There was no existing segment. */
  current = *CacheSeg;
  if (previous)
  {
     InsertHeadList(&previous->BcbSegmentListEntry, &current->BcbSegmentListEntry);
  }
  else
  {
     InsertHeadList(&Bcb->BcbSegmentListHead, &current->BcbSegmentListEntry);
  }
  KeReleaseSpinLock(&Bcb->BcbLock, oldIrql);
  InsertTailList(&CacheSegmentListHead, &current->CacheSegmentListEntry);
  InsertTailList(&CacheSegmentLRUListHead, &current->CacheSegmentLRUListEntry);
  KeReleaseGuardedMutex(&ViewLock);
#ifdef CACHE_BITMAP
  KeAcquireSpinLock(&CiCacheSegMappingRegionLock, &oldIrql);

  StartingOffset = RtlFindClearBitsAndSet(&CiCacheSegMappingRegionAllocMap, Bcb->CacheSegmentSize / PAGE_SIZE, CiCacheSegMappingRegionHint);

  if (StartingOffset == 0xffffffff)
  {
     DPRINT1("Out of CacheSeg mapping space\n");
     KeBugCheck(CACHE_MANAGER);
  }

  current->BaseAddress = CiCacheSegMappingRegionBase + StartingOffset * PAGE_SIZE;

  if (CiCacheSegMappingRegionHint == StartingOffset)
  {
     CiCacheSegMappingRegionHint += Bcb->CacheSegmentSize / PAGE_SIZE;
  }

  KeReleaseSpinLock(&CiCacheSegMappingRegionLock, oldIrql);
#else
  MmLockAddressSpace(MmGetKernelAddressSpace());
  current->BaseAddress = NULL;
  Status = MmCreateMemoryArea(MmGetKernelAddressSpace(),
			      0, // nothing checks for cache_segment mareas, so set to 0
			      &current->BaseAddress,
			      Bcb->CacheSegmentSize,
			      PAGE_READWRITE,
			      (PMEMORY_AREA*)&current->MemoryArea,
			      FALSE,
			      0,
			      BoundaryAddressMultiple);
  MmUnlockAddressSpace(MmGetKernelAddressSpace());
  if (!NT_SUCCESS(Status))
  {
     KeBugCheck(CACHE_MANAGER);
  }
#endif

  /* Create a virtual mapping for this memory area */
  MI_SET_USAGE(MI_USAGE_CACHE);
#if MI_TRACE_PFNS
  PWCHAR pos = NULL;
  ULONG len = 0;
  if ((Bcb->FileObject) && (Bcb->FileObject->FileName.Buffer))
  {
    pos = wcsrchr(Bcb->FileObject->FileName.Buffer, '\\');
    len = wcslen(pos) * sizeof(WCHAR);
    if (pos) snprintf(MI_PFN_CURRENT_PROCESS_NAME, min(16, len), "%S", pos);
  }   
#endif

  MmMapMemoryArea(current->BaseAddress, Bcb->CacheSegmentSize,
      MC_CACHE, PAGE_READWRITE);

  return(STATUS_SUCCESS);
}

NTSTATUS
NTAPI
CcRosGetCacheSegmentChain(PBCB Bcb,
			  ULONG FileOffset,
			  ULONG Length,
			  PCACHE_SEGMENT* CacheSeg)
{
  PCACHE_SEGMENT current;
  ULONG i;
  PCACHE_SEGMENT* CacheSegList;
  PCACHE_SEGMENT Previous = NULL;

  ASSERT(Bcb);

  DPRINT("CcRosGetCacheSegmentChain()\n");

  Length = ROUND_UP(Length, Bcb->CacheSegmentSize);

  CacheSegList = _alloca(sizeof(PCACHE_SEGMENT) *
			(Length / Bcb->CacheSegmentSize));

  /*
   * Look for a cache segment already mapping the same data.
   */
  for (i = 0; i < (Length / Bcb->CacheSegmentSize); i++)
    {
      ULONG CurrentOffset = FileOffset + (i * Bcb->CacheSegmentSize);
      current = CcRosLookupCacheSegment(Bcb, CurrentOffset);
      if (current != NULL)
	{
	  KeAcquireGuardedMutex(&ViewLock);

	  /* Move to tail of LRU list */
	  RemoveEntryList(&current->CacheSegmentLRUListEntry);
	  InsertTailList(&CacheSegmentLRUListHead, &current->CacheSegmentLRUListEntry);

	  KeReleaseGuardedMutex(&ViewLock);

	  CacheSegList[i] = current;
	}
      else
	{
	  CcRosCreateCacheSegment(Bcb, CurrentOffset, &current);
	  CacheSegList[i] = current;
	}
    }

  for (i = 0; i < (Length / Bcb->CacheSegmentSize); i++)
    {
      if (i == 0)
	{
	  *CacheSeg = CacheSegList[i];
	  Previous = CacheSegList[i];
	}
      else
	{
	  Previous->NextInChain = CacheSegList[i];
	  Previous = CacheSegList[i];
	}
    }
  ASSERT(Previous);
  Previous->NextInChain = NULL;

  return(STATUS_SUCCESS);
}

NTSTATUS
NTAPI
CcRosGetCacheSegment(PBCB Bcb,
		     ULONG FileOffset,
		     PULONG BaseOffset,
		     PVOID* BaseAddress,
		     PBOOLEAN UptoDate,
		     PCACHE_SEGMENT* CacheSeg)
{
   PCACHE_SEGMENT current;
   NTSTATUS Status;

   ASSERT(Bcb);

   DPRINT("CcRosGetCacheSegment()\n");

   /*
    * Look for a cache segment already mapping the same data.
    */
   current = CcRosLookupCacheSegment(Bcb, FileOffset);
   if (current == NULL)
   {
     /*
      * Otherwise create a new segment.
      */
      Status = CcRosCreateCacheSegment(Bcb, FileOffset, &current);
      if (!NT_SUCCESS(Status))
      {
	return Status;
      }
   }

   KeAcquireGuardedMutex(&ViewLock);

   /* Move to the tail of the LRU list */
   RemoveEntryList(&current->CacheSegmentLRUListEntry);
   InsertTailList(&CacheSegmentLRUListHead, &current->CacheSegmentLRUListEntry);

   KeReleaseGuardedMutex(&ViewLock);

   /*
    * Return information about the segment to the caller.
    */
   *UptoDate = current->Valid;
   *BaseAddress = current->BaseAddress;
   DPRINT("*BaseAddress %p\n", *BaseAddress);
   *CacheSeg = current;
   *BaseOffset = current->FileOffset;
   return(STATUS_SUCCESS);
}

NTSTATUS NTAPI
CcRosRequestCacheSegment(PBCB Bcb,
		      ULONG FileOffset,
		      PVOID* BaseAddress,
		      PBOOLEAN UptoDate,
		      PCACHE_SEGMENT* CacheSeg)
/*
 * FUNCTION: Request a page mapping for a BCB
 */
{
  ULONG BaseOffset;

  ASSERT(Bcb);

  if ((FileOffset % Bcb->CacheSegmentSize) != 0)
    {
      DPRINT1("Bad fileoffset %x should be multiple of %x",
        FileOffset, Bcb->CacheSegmentSize);
      KeBugCheck(CACHE_MANAGER);
    }

  return(CcRosGetCacheSegment(Bcb,
			   FileOffset,
			   &BaseOffset,
			   BaseAddress,
			   UptoDate,
			   CacheSeg));
}
#ifdef CACHE_BITMAP
#else
static VOID
CcFreeCachePage(PVOID Context, MEMORY_AREA* MemoryArea, PVOID Address,
		PFN_NUMBER Page, SWAPENTRY SwapEntry, BOOLEAN Dirty)
{
  ASSERT(SwapEntry == 0);
  if (Page != 0)
    {
        ASSERT(MmGetReferenceCountPage(Page) == 1);
      MmReleasePageMemoryConsumer(MC_CACHE, Page);
    }
}
#endif
NTSTATUS
CcRosInternalFreeCacheSegment(PCACHE_SEGMENT CacheSeg)
/*
 * FUNCTION: Releases a cache segment associated with a BCB
 */
{
#ifdef CACHE_BITMAP
  ULONG i;
  ULONG RegionSize;
  ULONG Base;
  PFN_NUMBER Page;
  KIRQL oldIrql;
#endif
  DPRINT("Freeing cache segment 0x%p\n", CacheSeg);
#if DBG
	if ( CacheSeg->Bcb->Trace )
	{
		DPRINT1("CacheMap 0x%p: deleting Cache Segment: 0x%p\n", CacheSeg->Bcb, CacheSeg );
	}
#endif
#ifdef CACHE_BITMAP
  RegionSize = CacheSeg->Bcb->CacheSegmentSize / PAGE_SIZE;

  /* Unmap all the pages. */
  for (i = 0; i < RegionSize; i++)
    {
      MmDeleteVirtualMapping(NULL,
			     CacheSeg->BaseAddress + (i * PAGE_SIZE),
			     FALSE,
			     NULL,
			     &Page);
      MmReleasePageMemoryConsumer(MC_CACHE, Page);
    }

  KeAcquireSpinLock(&CiCacheSegMappingRegionLock, &oldIrql);
  /* Deallocate all the pages used. */
  Base = (ULONG)(CacheSeg->BaseAddress - CiCacheSegMappingRegionBase) / PAGE_SIZE;

  RtlClearBits(&CiCacheSegMappingRegionAllocMap, Base, RegionSize);

  CiCacheSegMappingRegionHint = min (CiCacheSegMappingRegionHint, Base);

  KeReleaseSpinLock(&CiCacheSegMappingRegionLock, oldIrql);
#else
  MmLockAddressSpace(MmGetKernelAddressSpace());
  MmFreeMemoryArea(MmGetKernelAddressSpace(),
		   CacheSeg->MemoryArea,
		   CcFreeCachePage,
		   NULL);
  MmUnlockAddressSpace(MmGetKernelAddressSpace());
#endif
  ExFreeToNPagedLookasideList(&CacheSegLookasideList, CacheSeg);
  return(STATUS_SUCCESS);
}

NTSTATUS
NTAPI
CcRosFreeCacheSegment(PBCB Bcb, PCACHE_SEGMENT CacheSeg)
{
  NTSTATUS Status;
  KIRQL oldIrql;

  ASSERT(Bcb);

  DPRINT("CcRosFreeCacheSegment(Bcb 0x%p, CacheSeg 0x%p)\n",
         Bcb, CacheSeg);

  KeAcquireGuardedMutex(&ViewLock);
  KeAcquireSpinLock(&Bcb->BcbLock, &oldIrql);
  RemoveEntryList(&CacheSeg->BcbSegmentListEntry);
  RemoveEntryList(&CacheSeg->CacheSegmentListEntry);
  RemoveEntryList(&CacheSeg->CacheSegmentLRUListEntry);
  if (CacheSeg->Dirty)
  {
     RemoveEntryList(&CacheSeg->DirtySegmentListEntry);
     DirtyPageCount -= Bcb->CacheSegmentSize / PAGE_SIZE;

  }
  KeReleaseSpinLock(&Bcb->BcbLock, oldIrql);
  KeReleaseGuardedMutex(&ViewLock);

  Status = CcRosInternalFreeCacheSegment(CacheSeg);
  return(Status);
}

/*
 * @implemented
 */
VOID NTAPI
CcFlushCache(IN PSECTION_OBJECT_POINTERS SectionObjectPointers,
             IN PLARGE_INTEGER FileOffset OPTIONAL,
             IN ULONG Length,
             OUT PIO_STATUS_BLOCK IoStatus)
{
    PBCB Bcb;
    LARGE_INTEGER Offset;
    PCACHE_SEGMENT current;
    NTSTATUS Status;
    KIRQL oldIrql;

    DPRINT("CcFlushCache(SectionObjectPointers 0x%p, FileOffset 0x%p, Length %d, IoStatus 0x%p)\n",
           SectionObjectPointers, FileOffset, Length, IoStatus);

    if (SectionObjectPointers && SectionObjectPointers->SharedCacheMap)
    {
        Bcb = (PBCB)SectionObjectPointers->SharedCacheMap;
        ASSERT(Bcb);
        if (FileOffset)
        {
            Offset = *FileOffset;
        }
        else
        {
            Offset.QuadPart = (LONGLONG)0;
            Length = Bcb->FileSize.u.LowPart;
        }

        if (IoStatus)
        {
            IoStatus->Status = STATUS_SUCCESS;
            IoStatus->Information = 0;
        }

        while (Length > 0)
        {
            current = CcRosLookupCacheSegment (Bcb, Offset.u.LowPart);
            if (current != NULL)
            {
                if (current->Dirty)
                {
                    Status = CcRosFlushCacheSegment(current);
                    if (!NT_SUCCESS(Status) && IoStatus != NULL)
                    {
                        IoStatus->Status = Status;
                    }
                }
                KeReleaseMutex(&current->Mutex, 0);
                
                KeAcquireGuardedMutex(&ViewLock);
                KeAcquireSpinLock(&Bcb->BcbLock, &oldIrql);
                CcRosCacheSegmentDecRefCount(current);
                KeReleaseSpinLock(&Bcb->BcbLock, oldIrql);
                KeReleaseGuardedMutex(&ViewLock);
            }

            Offset.QuadPart += Bcb->CacheSegmentSize;
            if (Length > Bcb->CacheSegmentSize)
            {
                Length -= Bcb->CacheSegmentSize;
            }
            else
            {
                Length = 0;
            }
        }
    }
    else
    {
        if (IoStatus)
        {
            IoStatus->Status = STATUS_INVALID_PARAMETER;
        }
    }
}

NTSTATUS
NTAPI
CcRosDeleteFileCache(PFILE_OBJECT FileObject, PBCB Bcb)
/*
 * FUNCTION: Releases the BCB associated with a file object
 */
{
    PLIST_ENTRY current_entry;
    PCACHE_SEGMENT current;
    LIST_ENTRY FreeList;
    KIRQL oldIrql;

    ASSERT(Bcb);

    Bcb->RefCount++;
    KeReleaseGuardedMutex(&ViewLock);

    CcFlushCache(FileObject->SectionObjectPointer, NULL, 0, NULL);

    KeAcquireGuardedMutex(&ViewLock);
    Bcb->RefCount--;
    if (Bcb->RefCount == 0)
    {
        if (Bcb->BcbRemoveListEntry.Flink != NULL)
        {
            RemoveEntryList(&Bcb->BcbRemoveListEntry);
            Bcb->BcbRemoveListEntry.Flink = NULL;
        }

        FileObject->SectionObjectPointer->SharedCacheMap = NULL;

        /*
         * Release all cache segments.
         */
        InitializeListHead(&FreeList);
        KeAcquireSpinLock(&Bcb->BcbLock, &oldIrql);
        current_entry = Bcb->BcbSegmentListHead.Flink;
        while (!IsListEmpty(&Bcb->BcbSegmentListHead))
        {
            current_entry = RemoveTailList(&Bcb->BcbSegmentListHead);
            current = CONTAINING_RECORD(current_entry, CACHE_SEGMENT, BcbSegmentListEntry);
            RemoveEntryList(&current->CacheSegmentListEntry);
            RemoveEntryList(&current->CacheSegmentLRUListEntry);
            if (current->Dirty)
            {
                RemoveEntryList(&current->DirtySegmentListEntry);
                DirtyPageCount -= Bcb->CacheSegmentSize / PAGE_SIZE;
                DPRINT1("Freeing dirty segment\n");
            }
            InsertHeadList(&FreeList, &current->BcbSegmentListEntry);
        }
#if DBG
        Bcb->Trace = FALSE;
#endif
        KeReleaseSpinLock(&Bcb->BcbLock, oldIrql);

        KeReleaseGuardedMutex(&ViewLock);
        ObDereferenceObject (Bcb->FileObject);

        while (!IsListEmpty(&FreeList))
        {
            current_entry = RemoveTailList(&FreeList);
            current = CONTAINING_RECORD(current_entry, CACHE_SEGMENT, BcbSegmentListEntry);
            CcRosInternalFreeCacheSegment(current);
        }
        ExFreeToNPagedLookasideList(&BcbLookasideList, Bcb);
        KeAcquireGuardedMutex(&ViewLock);
    }
    return(STATUS_SUCCESS);
}

VOID
NTAPI
CcRosReferenceCache(PFILE_OBJECT FileObject)
{
  PBCB Bcb;
  KeAcquireGuardedMutex(&ViewLock);
  Bcb = (PBCB)FileObject->SectionObjectPointer->SharedCacheMap;
  ASSERT(Bcb);
  if (Bcb->RefCount == 0)
  {
     ASSERT(Bcb->BcbRemoveListEntry.Flink != NULL);
     RemoveEntryList(&Bcb->BcbRemoveListEntry);
     Bcb->BcbRemoveListEntry.Flink = NULL;

  }
  else
  {
     ASSERT(Bcb->BcbRemoveListEntry.Flink == NULL);
  }
  Bcb->RefCount++;
  KeReleaseGuardedMutex(&ViewLock);
}

VOID
NTAPI
CcRosSetRemoveOnClose(PSECTION_OBJECT_POINTERS SectionObjectPointer)
{
  PBCB Bcb;
  DPRINT("CcRosSetRemoveOnClose()\n");
  KeAcquireGuardedMutex(&ViewLock);
  Bcb = (PBCB)SectionObjectPointer->SharedCacheMap;
  if (Bcb)
  {
    Bcb->RemoveOnClose = TRUE;
    if (Bcb->RefCount == 0)
    {
      CcRosDeleteFileCache(Bcb->FileObject, Bcb);
    }
  }
  KeReleaseGuardedMutex(&ViewLock);
}


VOID
NTAPI
CcRosDereferenceCache(PFILE_OBJECT FileObject)
{
  PBCB Bcb;
  KeAcquireGuardedMutex(&ViewLock);
  Bcb = (PBCB)FileObject->SectionObjectPointer->SharedCacheMap;
  ASSERT(Bcb);
  if (Bcb->RefCount > 0)
  {
    Bcb->RefCount--;
    if (Bcb->RefCount == 0)
    {
       MmFreeSectionSegments(Bcb->FileObject);
          CcRosDeleteFileCache(FileObject, Bcb);
    }
  }
  KeReleaseGuardedMutex(&ViewLock);
}

NTSTATUS NTAPI
CcRosReleaseFileCache(PFILE_OBJECT FileObject)
/*
 * FUNCTION: Called by the file system when a handle to a file object
 * has been closed.
 */
{
  PBCB Bcb;

  KeAcquireGuardedMutex(&ViewLock);

  if (FileObject->SectionObjectPointer->SharedCacheMap != NULL)
  {
    Bcb = FileObject->SectionObjectPointer->SharedCacheMap;
    if (FileObject->PrivateCacheMap != NULL)
    {
      FileObject->PrivateCacheMap = NULL;
      if (Bcb->RefCount > 0)
      {
         Bcb->RefCount--;
	 if (Bcb->RefCount == 0)
	 {
            MmFreeSectionSegments(Bcb->FileObject);
	       CcRosDeleteFileCache(FileObject, Bcb);
	 }
      }
    }
  }
  KeReleaseGuardedMutex(&ViewLock);
  return(STATUS_SUCCESS);
}

NTSTATUS
NTAPI
CcTryToInitializeFileCache(PFILE_OBJECT FileObject)
{
   PBCB Bcb;
   NTSTATUS Status;

   KeAcquireGuardedMutex(&ViewLock);

   ASSERT(FileObject->SectionObjectPointer);
   Bcb = FileObject->SectionObjectPointer->SharedCacheMap;
   if (Bcb == NULL)
   {
      Status = STATUS_UNSUCCESSFUL;
   }
   else
   {
      if (FileObject->PrivateCacheMap == NULL)
      {
         FileObject->PrivateCacheMap = Bcb;
         Bcb->RefCount++;
      }
      if (Bcb->BcbRemoveListEntry.Flink != NULL)
      {
         RemoveEntryList(&Bcb->BcbRemoveListEntry);
         Bcb->BcbRemoveListEntry.Flink = NULL;
      }
      Status = STATUS_SUCCESS;
   }
   KeReleaseGuardedMutex(&ViewLock);

   return Status;
}


NTSTATUS NTAPI
CcRosInitializeFileCache(PFILE_OBJECT FileObject,
                         ULONG CacheSegmentSize,
                         PCACHE_MANAGER_CALLBACKS CallBacks,
                         PVOID LazyWriterContext)
/*
 * FUNCTION: Initializes a BCB for a file object
 */
{
   PBCB Bcb;

   Bcb = FileObject->SectionObjectPointer->SharedCacheMap;
   DPRINT("CcRosInitializeFileCache(FileObject 0x%p, Bcb 0x%p, CacheSegmentSize %d)\n",
           FileObject, Bcb, CacheSegmentSize);

   KeAcquireGuardedMutex(&ViewLock);
   if (Bcb == NULL)
   {
       Bcb = ExAllocateFromNPagedLookasideList(&BcbLookasideList);
       if (Bcb == NULL)
       {
           KeReleaseGuardedMutex(&ViewLock);
           return(STATUS_UNSUCCESSFUL);
       }
       memset(Bcb, 0, sizeof(BCB));
       ObReferenceObjectByPointer(FileObject,
           FILE_ALL_ACCESS,
           NULL,
           KernelMode);
       Bcb->FileObject = FileObject;
       Bcb->CacheSegmentSize = CacheSegmentSize;
       Bcb->Callbacks = CallBacks;
       Bcb->LazyWriteContext = LazyWriterContext;
       if (FileObject->FsContext)
       {
           Bcb->AllocationSize =
               ((PFSRTL_COMMON_FCB_HEADER)FileObject->FsContext)->AllocationSize;
           Bcb->FileSize =
               ((PFSRTL_COMMON_FCB_HEADER)FileObject->FsContext)->FileSize;
       }
       KeInitializeSpinLock(&Bcb->BcbLock);
       InitializeListHead(&Bcb->BcbSegmentListHead);
       FileObject->SectionObjectPointer->SharedCacheMap = Bcb;
   }
   if (FileObject->PrivateCacheMap == NULL)
   {
       FileObject->PrivateCacheMap = Bcb;
       Bcb->RefCount++;
   }
   if (Bcb->BcbRemoveListEntry.Flink != NULL)
   {
       RemoveEntryList(&Bcb->BcbRemoveListEntry);
       Bcb->BcbRemoveListEntry.Flink = NULL;
   }
   KeReleaseGuardedMutex(&ViewLock);

   return(STATUS_SUCCESS);
}

/*
 * @implemented
 */
PFILE_OBJECT NTAPI
CcGetFileObjectFromSectionPtrs(IN PSECTION_OBJECT_POINTERS SectionObjectPointers)
{
   PBCB Bcb;
   if (SectionObjectPointers && SectionObjectPointers->SharedCacheMap)
   {
      Bcb = (PBCB)SectionObjectPointers->SharedCacheMap;
      ASSERT(Bcb);
      return Bcb->FileObject;
   }
   return NULL;
}

VOID
INIT_FUNCTION
NTAPI
CcInitView(VOID)
{
#ifdef CACHE_BITMAP
  PMEMORY_AREA marea;
  PVOID Buffer;
  PHYSICAL_ADDRESS BoundaryAddressMultiple;
#endif

  DPRINT("CcInitView()\n");
#ifdef CACHE_BITMAP
  BoundaryAddressMultiple.QuadPart = 0;
  CiCacheSegMappingRegionHint = 0;
  CiCacheSegMappingRegionBase = NULL;

  MmLockAddressSpace(MmGetKernelAddressSpace());

  Status = MmCreateMemoryArea(MmGetKernelAddressSpace(),
			      MEMORY_AREA_CACHE_SEGMENT,
			      &CiCacheSegMappingRegionBase,
			      CI_CACHESEG_MAPPING_REGION_SIZE,
			      PAGE_READWRITE,
			      &marea,
			      FALSE,
			      0,
			      BoundaryAddressMultiple);
  MmUnlockAddressSpace(MmGetKernelAddressSpace());
  if (!NT_SUCCESS(Status))
    {
      KeBugCheck(CACHE_MANAGER);
    }

  Buffer = ExAllocatePool(NonPagedPool, CI_CACHESEG_MAPPING_REGION_SIZE / (PAGE_SIZE * 8));
  if (!Buffer)
  {
    KeBugCheck(CACHE_MANAGER);
  }

  RtlInitializeBitMap(&CiCacheSegMappingRegionAllocMap, Buffer, CI_CACHESEG_MAPPING_REGION_SIZE / PAGE_SIZE);
  RtlClearAllBits(&CiCacheSegMappingRegionAllocMap);

  KeInitializeSpinLock(&CiCacheSegMappingRegionLock);
#endif
  InitializeListHead(&CacheSegmentListHead);
  InitializeListHead(&DirtySegmentListHead);
  InitializeListHead(&CacheSegmentLRUListHead);
  InitializeListHead(&ClosedListHead);
  KeInitializeGuardedMutex(&ViewLock);
  ExInitializeNPagedLookasideList (&iBcbLookasideList,
	                           NULL,
				   NULL,
				   0,
				   sizeof(INTERNAL_BCB),
				   TAG_IBCB,
				   20);
  ExInitializeNPagedLookasideList (&BcbLookasideList,
	                           NULL,
				   NULL,
				   0,
				   sizeof(BCB),
				   TAG_BCB,
				   20);
  ExInitializeNPagedLookasideList (&CacheSegLookasideList,
	                           NULL,
				   NULL,
				   0,
				   sizeof(CACHE_SEGMENT),
				   TAG_CSEG,
				   20);

  MmInitializeMemoryConsumer(MC_CACHE, CcRosTrimCache);

  CcInitCacheZeroPage();

}

/* EOF */