/*
 * 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=%lu, Dirty %u, PageOut %lu\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=%lu, Dirty %u, PageOut %lu\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 %lu, Dirty %u, PageOut %lu\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 -= VACB_MAPPING_GRANULARITY / 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 %lu)\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, FALSE);
            current->Bcb->Callbacks->ReleaseFromLazyWrite(
                current->Bcb->LazyWriteContext);
            CcRosCacheSegmentDecRefCount(current);
            continue;
        }

        PagesPerSegment = VACB_MAPPING_GRANULARITY / PAGE_SIZE;

        KeReleaseGuardedMutex(&ViewLock);

        Status = CcRosFlushCacheSegment(current);

        KeReleaseMutex(&current->Mutex, FALSE);
        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 %lu)\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 < VACB_MAPPING_GRANULARITY / 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 = VACB_MAPPING_GRANULARITY / 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 %lu 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 %lu 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 %u)\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 += VACB_MAPPING_GRANULARITY / 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, FALSE);

    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 %lu)\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 (IsPointInSegment(current->FileOffset, VACB_MAPPING_GRANULARITY,
                             FileOffset))
        {
            CcRosCacheSegmentIncRefCount(current);
            KeReleaseSpinLock(&Bcb->BcbLock, oldIrql);
            KeReleaseGuardedMutex(&ViewLock);
            KeWaitForSingleObject(&current->Mutex,
                                  Executive,
                                  KernelMode,
                                  FALSE,
                                  NULL);
            return current;
        }
        if (current->FileOffset > FileOffset)
            break;
        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 %lu)\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 += VACB_MAPPING_GRANULARITY / 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, FALSE);

    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 %lu, NowDirty %u)\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 += VACB_MAPPING_GRANULARITY / PAGE_SIZE;
    }

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

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

    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

    ASSERT(Bcb);

    DPRINT("CcRosCreateCacheSegment()\n");

    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, VACB_MAPPING_GRANULARITY);
    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 (IsPointInSegment(current->FileOffset, VACB_MAPPING_GRANULARITY,
                             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, FALSE);
            KeReleaseGuardedMutex(&ViewLock);
            ExFreeToNPagedLookasideList(&CacheSegLookasideList, *CacheSeg);
            *CacheSeg = current;
            KeWaitForSingleObject(&current->Mutex,
                                  Executive,
                                  KernelMode,
                                  FALSE,
                                  NULL);
            return STATUS_SUCCESS;
        }
        if (current->FileOffset < FileOffset)
        {
            ASSERT(previous == NULL ||
                   previous->FileOffset < current->FileOffset);
            previous = current;
        }
        if (current->FileOffset > FileOffset)
            break;
        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,
                                            VACB_MAPPING_GRANULARITY / 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 += VACB_MAPPING_GRANULARITY / 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,
                                VACB_MAPPING_GRANULARITY,
                                PAGE_READWRITE,
                                (PMEMORY_AREA*)&current->MemoryArea,
                                FALSE,
                                0,
                                PAGE_SIZE);
    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, VACB_MAPPING_GRANULARITY,
                    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, VACB_MAPPING_GRANULARITY);

    CacheSegList = _alloca(sizeof(PCACHE_SEGMENT) *
                           (Length / VACB_MAPPING_GRANULARITY));

    /*
     * Look for a cache segment already mapping the same data.
     */
    for (i = 0; i < (Length / VACB_MAPPING_GRANULARITY); i++)
    {
        ULONG CurrentOffset = FileOffset + (i * VACB_MAPPING_GRANULARITY);
        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 / VACB_MAPPING_GRANULARITY; 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 % VACB_MAPPING_GRANULARITY != 0)
    {
        DPRINT1("Bad fileoffset %x should be multiple of %x",
                FileOffset, VACB_MAPPING_GRANULARITY);
        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 = VACB_MAPPING_GRANULARITY / 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;
}

/*
 * @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 %lu, 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, FALSE);

                KeAcquireGuardedMutex(&ViewLock);
                KeAcquireSpinLock(&Bcb->BcbLock, &oldIrql);
                CcRosCacheSegmentDecRefCount(current);
                KeReleaseSpinLock(&Bcb->BcbLock, oldIrql);
                KeReleaseGuardedMutex(&ViewLock);
            }

            Offset.QuadPart += VACB_MAPPING_GRANULARITY;
            if (Length > VACB_MAPPING_GRANULARITY)
            {
                Length -= VACB_MAPPING_GRANULARITY;
            }
            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);
        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 -= VACB_MAPPING_GRANULARITY / 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,
    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)\n",
           FileObject, Bcb);

    KeAcquireGuardedMutex(&ViewLock);
    if (Bcb == NULL)
    {
        Bcb = ExAllocateFromNPagedLookasideList(&BcbLookasideList);
        if (Bcb == NULL)
        {
            KeReleaseGuardedMutex(&ViewLock);
            return STATUS_UNSUCCESSFUL;
        }
        RtlZeroMemory(Bcb, sizeof(*Bcb));
        ObReferenceObjectByPointer(FileObject,
                                   FILE_ALL_ACCESS,
                                   NULL,
                                   KernelMode);
        Bcb->FileObject = FileObject;
        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;
#endif

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

    MmLockAddressSpace(MmGetKernelAddressSpace());

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

    Buffer = ExAllocatePoolWithTag(NonPagedPool,
                                   CI_CACHESEG_MAPPING_REGION_SIZE / (PAGE_SIZE * 8),
                                   TAG_CC);
    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 */