windows-nt-4.0/private/ntos/fastfat/cachesup.c

/*++

Copyright (c) 1990  Microsoft Corporation

Module Name:

    cache.c

Abstract:

    This module implements the cache management routines for the Fat
    FSD and FSP, by calling the Common Cache Manager.

Author:

    Tom Miller      [TomM]      26-Jan-1990

Revision History:

--*/

#include "FatProcs.h"

//
//  The Bug check file id for this module
//

#define BugCheckFileId                   (FAT_BUG_CHECK_CACHESUP)

//
//  Local debug trace level
//

#define Dbg                              (DEBUG_TRACE_CACHESUP)

#ifdef ALLOC_PRAGMA
#pragma alloc_text(PAGE, FatCompleteMdl)
#pragma alloc_text(PAGE, FatOpenDirectoryFile)
#pragma alloc_text(PAGE, FatOpenEaFile)
#pragma alloc_text(PAGE, FatPinMappedData)
#pragma alloc_text(PAGE, FatReadDirectoryFile)
#pragma alloc_text(PAGE, FatPrepareWriteDirectoryFile)
#pragma alloc_text(PAGE, FatPrepareWriteVolumeFile)
#pragma alloc_text(PAGE, FatReadVolumeFile)
#pragma alloc_text(PAGE, FatRepinBcb)
#pragma alloc_text(PAGE, FatUnpinRepinnedBcbs)
#pragma alloc_text(PAGE, FatZeroData)
#pragma alloc_text(PAGE, FatSyncUninitializeCacheMap)
#endif


VOID
FatReadVolumeFile (
    IN PIRP_CONTEXT IrpContext,
    IN PVCB Vcb,
    IN VBO StartingVbo,
    IN ULONG ByteCount,
    OUT PBCB *Bcb,
    OUT PVOID *Buffer
    )

/*++

Routine Description:

    This routine is called when the specified range of sectors is to be
    read into the cache.  In fat, the volume file only contains the boot
    sector, reserved sectors, and the "fat(s)."  Thus the volume file is
    of fixed size and only extends up to (but not not including) the root
    directory entry, and will never move or change size.

    The fat volume file is also peculiar in that, since it starts at the
    logical beginning of the disk, Vbo == Lbo.

Arguments:

    Vcb - Pointer to the VCB for the volume

    StartingVbo - The virtual offset of the first desired byte

    ByteCount - Number of bytes desired

    Bcb - Returns a pointer to the BCB which is valid until unpinned

    Buffer - Returns a pointer to the sectors, which is valid until unpinned

--*/

{
    LARGE_INTEGER Vbo;

    //
    //  Check to see that all references are within the Bios Parameter Block
    //  or the fat(s).  A special case is made when StartingVbo == 0 at
    //  mounting time since we do not know how big the fat is.
    //

    ASSERT( ((StartingVbo == 0) || ((StartingVbo + ByteCount) <= (ULONG)
            (FatRootDirectoryLbo( &Vcb->Bpb ) + PAGE_SIZE))));

    DebugTrace(+1, Dbg, "FatReadVolumeFile\n", 0);
    DebugTrace( 0, Dbg, "Vcb         = %08lx\n", Vcb);
    DebugTrace( 0, Dbg, "StartingVbo = %08lx\n", StartingVbo);
    DebugTrace( 0, Dbg, "ByteCount   = %08lx\n", ByteCount);

    //
    //  Call the Cache manager to attempt the transfer.
    //

    Vbo.QuadPart = StartingVbo;

    if (!CcMapData( Vcb->VirtualVolumeFile,
                    &Vbo,
                    ByteCount,
                    BooleanFlagOn(IrpContext->Flags, IRP_CONTEXT_FLAG_WAIT),
                    Bcb,
                    Buffer )) {

        ASSERT( !FlagOn(IrpContext->Flags, IRP_CONTEXT_FLAG_WAIT) );

        //
        // Could not read the data without waiting (cache miss).
        //

        FatRaiseStatus( IrpContext, STATUS_CANT_WAIT );
    }

    DbgDoit( IrpContext->PinCount += 1 )

    DebugTrace(-1, Dbg, "FatReadVolumeFile -> VOID, *BCB = %08lx\n", *Bcb);

    return;
}


VOID
FatPrepareWriteVolumeFile (
    IN PIRP_CONTEXT IrpContext,
    IN PVCB Vcb,
    IN VBO StartingVbo,
    IN ULONG ByteCount,
    OUT PBCB *Bcb,
    OUT PVOID *Buffer,
    IN BOOLEAN Zero
    )

/*++

Routine Description:

    This routine first looks to see if the specified range of sectors,
    is already in the cache.  If so, it increments the BCB PinCount,
    sets the BCB dirty, and returns with the location of the sectors.

    If the sectors are not in the cache and Wait is TRUE, it finds a
    free BCB (potentially causing a flush), and clears out the entire
    buffer.  Once this is done, it increments the BCB PinCount, sets the
    BCB dirty, and returns with the location of the sectors.

    If the sectors are not in the cache and Wait is FALSE, this routine
    raises STATUS_CANT_WAIT.

Arguments:

    Vcb - Pointer to the VCB for the volume

    StartingVbo - The virtual offset of the first byte to be written

    ByteCount - Number of bytes to be written

    Bcb - Returns a pointer to the BCB which is valid until unpinned

    Buffer - Returns a pointer to the sectors, which is valid until unpinned

    Zero - Supplies TRUE if the specified range of bytes should be zeroed

--*/

{
    LARGE_INTEGER Vbo;

    //
    //  Check to see that all references are within the Bios Parameter Block
    //  or the fat(s).
    //

    ASSERT( ((StartingVbo + ByteCount) <= (ULONG)
            (FatRootDirectoryLbo( &Vcb->Bpb ))));

    DebugTrace(+1, Dbg, "FatPrepareWriteVolumeFile\n", 0);
    DebugTrace( 0, Dbg, "Vcb         = %08lx\n", Vcb);
    DebugTrace( 0, Dbg, "StartingVbo = %08lx\n", (ULONG)StartingVbo);
    DebugTrace( 0, Dbg, "ByteCount   = %08lx\n", ByteCount);
    DebugTrace( 0, Dbg, "Zero        = %08lx\n", Zero);

    //
    //  Call the Cache manager to attempt the transfer.
    //

    Vbo.QuadPart = StartingVbo;

    if (!CcPinRead( Vcb->VirtualVolumeFile,
                    &Vbo,
                    ByteCount,
                    BooleanFlagOn(IrpContext->Flags, IRP_CONTEXT_FLAG_WAIT),
                    Bcb,
                    Buffer )) {

        ASSERT( !FlagOn(IrpContext->Flags, IRP_CONTEXT_FLAG_WAIT) );

        //
        // Could not read the data without waiting (cache miss).
        //

        FatRaiseStatus( IrpContext, STATUS_CANT_WAIT );
    }

    //
    //  This keeps the data pinned until we complete the request
    //  and writes the dirty bit through to the disk.
    //

    DbgDoit( IrpContext->PinCount += 1 )

    try {

        if (Zero) {
            RtlZeroMemory( *Buffer, ByteCount );
        }

        CcSetDirtyPinnedData( *Bcb, NULL );

        FatSetDirtyBcb( IrpContext, *Bcb, Vcb );

    } finally {

        if (AbnormalTermination()) {

            FatUnpinBcb(IrpContext, *Bcb);
        }
    }

    DebugTrace(-1, Dbg, "FatPrepareWriteVolumeFile -> VOID, *Bcb = %08lx\n", *Bcb);

    return;
}


VOID
FatReadDirectoryFile (
    IN PIRP_CONTEXT IrpContext,
    IN PDCB Dcb,
    IN VBO StartingVbo,
    IN ULONG ByteCount,
    IN BOOLEAN Pin,
    OUT PBCB *Bcb,
    OUT PVOID *Buffer,
    OUT PNTSTATUS Status
    )

/*++

Routine Description:

    This routine is called when the specified range of sectors is to be
    read into the cache.  If the desired range falls beyond the current
    cache mapping, the fat will be searched, and if the desired range can
    be satisfied, the cache mapping will be extended and the MCB updated
    accordingly.

Arguments:

    Dcb - Pointer to the DCB for the directory

    StartingVbo - The virtual offset of the first desired byte

    ByteCount - Number of bytes desired

    Pin - Tells us if we should pin instead of just mapping.

    Bcb - Returns a pointer to the BCB which is valid until unpinned

    Buffer - Returns a pointer to the sectors, which is valid until unpinned

    Status - Returns the status of the operation.

--*/

{
    LARGE_INTEGER Vbo;

    DebugTrace(+1, Dbg, "FatReadDirectoryFile\n", 0);
    DebugTrace( 0, Dbg, "Dcb         = %08lx\n", Dcb);
    DebugTrace( 0, Dbg, "StartingVbo = %08lx\n", StartingVbo);
    DebugTrace( 0, Dbg, "ByteCount   = %08lx\n", ByteCount);

    //
    //  Check for the zero case
    //

    if (ByteCount == 0) {

        DebugTrace(0, Dbg, "Nothing to read\n", 0);

        *Status = STATUS_SUCCESS;

        DebugTrace(-1, Dbg, "FatReadDirectoryFile -> VOID\n", 0);
        return;
    }

    //
    //  If we need to create a directory file and initialize the
    //  cachemap, do so.
    //

    FatOpenDirectoryFile( IrpContext, Dcb );

    //
    //  Now if the transfer is beyond the allocation size return EOF.
    //

    if (StartingVbo >= Dcb->Header.AllocationSize.LowPart) {

        DebugTrace(0, Dbg, "End of file read for directory\n", 0);

        *Status = STATUS_END_OF_FILE;

        DebugTrace(-1, Dbg, "FatReadDirectoryFile -> VOID\n", 0);
        return;
    }

    //
    // If the caller is trying to read past the EOF, truncate the
    // read.
    //

    ByteCount = (Dcb->Header.AllocationSize.LowPart - StartingVbo < ByteCount) ?
                 Dcb->Header.AllocationSize.LowPart - StartingVbo : ByteCount;

    ASSERT( ByteCount != 0 );

    //
    //  Call the Cache manager to attempt the transfer.
    //

    Vbo.QuadPart = StartingVbo;

    if (Pin ?

        !CcPinRead( Dcb->Specific.Dcb.DirectoryFile,
                    &Vbo,
                    ByteCount,
                    BooleanFlagOn(IrpContext->Flags, IRP_CONTEXT_FLAG_WAIT),
                    Bcb,
                    Buffer )
        :

        !CcMapData( Dcb->Specific.Dcb.DirectoryFile,
                    &Vbo,
                    ByteCount,
                    BooleanFlagOn(IrpContext->Flags, IRP_CONTEXT_FLAG_WAIT),
                    Bcb,
                    Buffer ) ) {

        //
        // Could not read the data without waiting (cache miss).
        //

        FatRaiseStatus( IrpContext, STATUS_CANT_WAIT );
    }

    DbgDoit( IrpContext->PinCount += 1 )

    *Status = STATUS_SUCCESS;

    DebugTrace(-1, Dbg, "FatReadDirectoryFile -> VOID, *BCB = %08lx\n", *Bcb);

    return;
}


VOID
FatPrepareWriteDirectoryFile (
    IN PIRP_CONTEXT IrpContext,
    IN PDCB Dcb,
    IN VBO StartingVbo,
    IN ULONG ByteCount,
    OUT PBCB *Bcb,
    OUT PVOID *Buffer,
    IN BOOLEAN Zero,
    OUT PNTSTATUS Status
    )

/*++

Routine Description:

    This routine first looks to see if the specified range of sectors
    is already in the cache.  If so, it increments the BCB PinCount,
    sets the BCB dirty, and returns TRUE with the location of the sectors.

    The IrpContext->Flags .. Wait == TRUE/FALSE actions of this routine are identical to
    FatPrepareWriteVolumeFile() above.

Arguments:

    Dcb - Pointer to the DCB for the directory

    StartingVbo - The virtual offset of the first byte to be written

    ByteCount - Number of bytes to be written

    Bcb - Returns a pointer to the BCB which is valid until unpinned

    Buffer - Returns a pointer to the sectors, which is valid until unpinned

    Zero - Supplies TRUE if the specified range of bytes should be zeroed

    Status - Returns the status of the operation.

--*/

{
    LARGE_INTEGER Vbo;
    ULONG InitialAllocation;
    BOOLEAN UnwindWeAllocatedDiskSpace = FALSE;
    ULONG ClusterSize;

    DebugTrace(+1, Dbg, "FatPrepareWriteDirectoryFile\n", 0);
    DebugTrace( 0, Dbg, "Dcb         = %08lx\n", Dcb);
    DebugTrace( 0, Dbg, "StartingVbo = %08lx\n", (ULONG)StartingVbo);
    DebugTrace( 0, Dbg, "ByteCount   = %08lx\n", ByteCount);
    DebugTrace( 0, Dbg, "Zero        = %08lx\n", Zero);

    *Bcb = NULL;

    //
    //  If we need to create a directory file and initialize the
    //  cachemap, do so.
    //

    FatOpenDirectoryFile( IrpContext, Dcb );

    //
    //  If the transfer is beyond the allocation size we need to
    //  extend the directory's allocation.  The call to
    //  AddFileAllocation will raise a condition if
    //  it runs out of disk space.  Note that the root directory
    //  cannot be extended.
    //

    Vbo.QuadPart = StartingVbo;

    try {

        if (StartingVbo + ByteCount > Dcb->Header.AllocationSize.LowPart) {

            if (NodeType(Dcb) == FAT_NTC_ROOT_DCB) {

                FatRaiseStatus( IrpContext, STATUS_DISK_FULL );
            }

            DebugTrace(0, Dbg, "Try extending normal directory\n", 0);

            InitialAllocation = Dcb->Header.AllocationSize.LowPart;

            FatAddFileAllocation( IrpContext,
                                  Dcb,
                                  Dcb->Specific.Dcb.DirectoryFile,
                                  StartingVbo + ByteCount );

            UnwindWeAllocatedDiskSpace = TRUE;

            //
            //  Inform the cache manager of the new allocation
            //

            Dcb->Header.FileSize.LowPart =
                Dcb->Header.AllocationSize.LowPart;

            CcSetFileSizes( Dcb->Specific.Dcb.DirectoryFile,
                            (PCC_FILE_SIZES)&Dcb->Header.AllocationSize );

            //
            //  Set up the Bitmap buffer if it is not big enough already
            //

            FatCheckFreeDirentBitmap( IrpContext, Dcb );

            //
            //  The newly allocated clusters should be zeroed starting at
            //  the previous allocation size
            //

            Zero = TRUE;
            Vbo.QuadPart = InitialAllocation;
            ByteCount = Dcb->Header.AllocationSize.LowPart - InitialAllocation;
        }

        //
        // Call the Cache Manager to attempt the transfer, going one cluster
        // at a time to avoid pinning across a page boundary.
        //

        ClusterSize =
            1 << Dcb->Vcb->AllocationSupport.LogOfBytesPerCluster;

        while (ByteCount > 0) {

            ULONG BytesToPin;

            *Bcb = NULL;

            if (ByteCount > ClusterSize) {
                BytesToPin = ClusterSize;
            } else {
                BytesToPin = ByteCount;
            }

            ASSERT( (Vbo.QuadPart / ClusterSize) ==
                    (Vbo.QuadPart + BytesToPin - 1)/ClusterSize );

            if (!CcPinRead( Dcb->Specific.Dcb.DirectoryFile,
                            &Vbo,
                            BytesToPin,
                            BooleanFlagOn(IrpContext->Flags, IRP_CONTEXT_FLAG_WAIT),
                            Bcb,
                            Buffer )) {
    
                //
                // Could not read the data without waiting (cache miss).
                //

                FatRaiseStatus( IrpContext, STATUS_CANT_WAIT );
            }

            if (Zero) {
                RtlZeroMemory( *Buffer, BytesToPin );
                CcSetDirtyPinnedData( *Bcb, NULL );
            }

            ByteCount -= BytesToPin;
            Vbo.QuadPart += BytesToPin;

            if (ByteCount > 0) {
                FatUnpinBcb( IrpContext, *Bcb );
            }
        }

        CcSetDirtyPinnedData( *Bcb, NULL );

        //
        //  This keeps the data pinned until we complete the request
        //  and writes the dirty bit through to the disk.
        //

        DbgDoit( IrpContext->PinCount += 1 )

        FatSetDirtyBcb( IrpContext, *Bcb, Dcb->Vcb );

        *Status = STATUS_SUCCESS;


    } finally {

        DebugUnwind( FatPrepareWriteDirectoryFile );

        if (AbnormalTermination()) {

            if (UnwindWeAllocatedDiskSpace == TRUE) {

                FatTruncateFileAllocation( IrpContext, Dcb, InitialAllocation );
            }

            if (*Bcb) {

                FatUnpinBcb(IrpContext, *Bcb);
            }
        }

        DebugTrace(-1, Dbg, "FatPrepareWriteDirectoryFile -> (VOID), *Bcb = %08lx\n", *Bcb);
    }

    return;
}


VOID
FatOpenDirectoryFile (
    IN PIRP_CONTEXT IrpContext,
    IN PDCB Dcb
    )

/*++

Routine Description:

    This routine opens a new directory file if one is not already open.

Arguments:

    Dcb - Pointer to the DCB for the directory

Return Value:

    None.

--*/

{
    DebugTrace(+1, Dbg, "FatOpenDirectoryFile\n", 0);
    DebugTrace( 0, Dbg, "Dcb = %08lx\n", Dcb);

    //
    //  If we haven't yet set the correct AllocationSize, do so.
    //

    if (Dcb->Header.AllocationSize.LowPart == 0xffffffff) {

        FatLookupFileAllocationSize( IrpContext, Dcb );

        Dcb->Header.FileSize.LowPart =
        Dcb->Header.AllocationSize.LowPart;

        //
        //  Setup the Bitmap buffer if it is not big enough already
        //

        FatCheckFreeDirentBitmap( IrpContext, Dcb );
    }

    //
    //  Check if we need to create a directory file.
    //
    //  We first do a spot check and then synchronize and check again.
    //

    if (Dcb->Specific.Dcb.DirectoryFile == NULL) {

        ExAcquireFastMutex( &Dcb->Vcb->DirectoryFileCreationMutex );

        try {

            if (Dcb->Specific.Dcb.DirectoryFile == NULL) {

                PFILE_OBJECT DirectoryFileObject;

                PDEVICE_OBJECT RealDevice;

                //
                //  Create the special file object for the directory file, and set
                //  up its pointers back to the Dcb and the section object pointer.
                //  Note that setting the DirectoryFile pointer in the Dcb has
                //  to be the last thing done.
                //

                RealDevice = Dcb->Vcb->CurrentDevice;

                DirectoryFileObject = IoCreateStreamFileObject( NULL, RealDevice );

                FatSetFileObject( DirectoryFileObject,
                                  DirectoryFile,
                                  Dcb,
                                  NULL );

                DirectoryFileObject->SectionObjectPointer = &Dcb->NonPaged->SectionObjectPointers;

                DirectoryFileObject->ReadAccess = TRUE;
                DirectoryFileObject->WriteAccess = TRUE;
                DirectoryFileObject->DeleteAccess = TRUE;

                Dcb->Specific.Dcb.DirectoryFileOpenCount += 1;

                Dcb->Specific.Dcb.DirectoryFile = DirectoryFileObject;
            }

        } finally {

            ExReleaseFastMutex( &Dcb->Vcb->DirectoryFileCreationMutex );
        }
    }

    //
    //  Finally check if we need to initialize the Cache Map for the
    //  directory file.  The size of the section we are going to map
    //  the current allocation size for the directory.  Note that the
    //  cache manager will provide syncronization for us.
    //

    if ( Dcb->Specific.Dcb.DirectoryFile->PrivateCacheMap == NULL ) {

        Dcb->Header.ValidDataLength = FatMaxLarge;
        Dcb->ValidDataToDisk = MAXULONG;

        CcInitializeCacheMap( Dcb->Specific.Dcb.DirectoryFile,
                              (PCC_FILE_SIZES)&Dcb->Header.AllocationSize,
                              TRUE,
                              &FatData.CacheManagerNoOpCallbacks,
                              Dcb );
    }

    DebugTrace(-1, Dbg, "FatOpenDirectoryFile -> VOID\n", 0);

    return;
}


PFILE_OBJECT
FatOpenEaFile (
    IN PIRP_CONTEXT IrpContext,
    IN PFCB EaFcb
    )

/*++

Routine Description:

    This routine opens the Ea file.

Arguments:

    EaFcb - Pointer to the Fcb for the Ea file.

Return Value:

    Pointer to the new file object.

--*/

{
    PFILE_OBJECT EaFileObject;
    PDEVICE_OBJECT RealDevice;

    DebugTrace(+1, Dbg, "FatOpenEaFile\n", 0);
    DebugTrace( 0, Dbg, "EaFcb = %08lx\n", EaFcb);

    //
    //  Create the special file object for the ea file, and set
    //  up its pointers back to the Fcb and the section object pointer
    //

    RealDevice = EaFcb->Vcb->CurrentDevice;

    EaFileObject = IoCreateStreamFileObject( NULL, RealDevice );

    FatSetFileObject( EaFileObject,
                      EaFile,
                      EaFcb,
                      NULL );

    EaFileObject->SectionObjectPointer = &EaFcb->NonPaged->SectionObjectPointers;

    EaFileObject->ReadAccess = TRUE;
    EaFileObject->WriteAccess = TRUE;

    //
    //  Finally check if we need to initialize the Cache Map for the
    //  ea file.  The size of the section we are going to map
    //  the current allocation size for the Fcb.
    //

    EaFcb->Header.ValidDataLength = FatMaxLarge;

    CcInitializeCacheMap( EaFileObject,
                          (PCC_FILE_SIZES)&EaFcb->Header.AllocationSize,
                          TRUE,
                          &FatData.CacheManagerCallbacks,
                          EaFcb );

    CcSetAdditionalCacheAttributes( EaFileObject, TRUE, TRUE );

    DebugTrace(-1, Dbg, "FatOpenEaFile -> %08lx\n", EaFileObject);

    UNREFERENCED_PARAMETER( IrpContext );

    return EaFileObject;
}


VOID
FatSetDirtyBcb (
    IN PIRP_CONTEXT IrpContext,
    IN PBCB Bcb,
    IN PVCB Vcb OPTIONAL
    )

/*++

Routine Description:

    This routine saves a reference to the bcb in the irp context and
    sets the bcb dirty.  This will have the affect of keeping the page in
    memory until we complete the request

    In addition, a DPC is set to fire in 5 seconds (or if one is pending,
    pushed back 5 seconds) to mark the volume clean.

Arguments:

    Bcb - Supplies the Bcb being set dirty

Return Value:

    None.

--*/

{
    DebugTrace(+1, Dbg, "FatSetDirtyBcb\n", 0 );
    DebugTrace( 0, Dbg, "IrpContext = %08lx\n", IrpContext );
    DebugTrace( 0, Dbg, "Bcb        = %08lx\n", Bcb );
    DebugTrace( 0, Dbg, "Vcb        = %08lx\n", Vcb );

    //
    //  Repin the bcb
    //

    FatRepinBcb( IrpContext, Bcb );

    //
    //  Set the bcb dirty
    //

    CcSetDirtyPinnedData( Bcb, NULL );

    //
    //  Set the volume dirty if we were given a Vcb that we want to
    //  perform clean volume processing on, and return.
    //

    if ( ARGUMENT_PRESENT(Vcb) &&
         !FlagOn(Vcb->VcbState, VCB_STATE_FLAG_FLOPPY) ) {

        KIRQL SavedIrql;

        BOOLEAN SetTimer;

        LARGE_INTEGER TimeSincePreviousCall;
        LARGE_INTEGER CurrentTime;

        //
        //  "Borrow" the irp context spinlock.
        //

        KeQuerySystemTime( &CurrentTime );

        KeAcquireSpinLock( &FatData.StrucSupSpinLock, &SavedIrql );

        TimeSincePreviousCall.QuadPart =
                CurrentTime.QuadPart - Vcb->LastFatMarkVolumeDirtyCall.QuadPart;

        //
        //  If more than one second has elapsed since the prior call
        //  to here, bump the timer up again and see if we need to
        //  physically mark the volume dirty.
        //

        if ( (TimeSincePreviousCall.HighPart != 0) ||
             (TimeSincePreviousCall.LowPart > (1000 * 1000 * 10)) ) {

            SetTimer = TRUE;

        } else {

            SetTimer = FALSE;
        }

        KeReleaseSpinLock( &FatData.StrucSupSpinLock, SavedIrql );

        if ( SetTimer ) {

            LARGE_INTEGER EightSecondsFromNow;

            EightSecondsFromNow.QuadPart = (LONG)-8*1000*1000*10;

            (VOID)KeCancelTimer( &Vcb->CleanVolumeTimer );
            (VOID)KeRemoveQueueDpc( &Vcb->CleanVolumeDpc );

            //
            //  We have now synchronized with anybody clearing the dirty
            //  flag, so we can now see if we really have to actually write
            //  out the physical bit.
            //

            if ( !FlagOn(Vcb->VcbState, VCB_STATE_FLAG_VOLUME_DIRTY) ) {

                //
                //  We want to really mark the volume dirty now.
                //

                if (!FlagOn(Vcb->VcbState, VCB_STATE_FLAG_MOUNTED_DIRTY)) {

                    FatMarkVolumeDirty( IrpContext, Vcb, FALSE );
                }

                SetFlag( Vcb->VcbState, VCB_STATE_FLAG_VOLUME_DIRTY );

                //
                //  Lock the volume if it is removable.
                //

                if (FlagOn( Vcb->VcbState, VCB_STATE_FLAG_REMOVABLE_MEDIA)) {

                    FatToggleMediaEjectDisable( IrpContext, Vcb, TRUE );
                }
            }

            KeAcquireSpinLock( &FatData.StrucSupSpinLock, &SavedIrql );

            KeQuerySystemTime( &Vcb->LastFatMarkVolumeDirtyCall );

            KeReleaseSpinLock( &FatData.StrucSupSpinLock, SavedIrql );

            KeSetTimer( &Vcb->CleanVolumeTimer,
                        EightSecondsFromNow,
                        &Vcb->CleanVolumeDpc );
        }
    }

    DebugTrace(-1, Dbg, "FatSetDirtyBcb -> VOID\n", 0 );
}


VOID
FatRepinBcb (
    IN PIRP_CONTEXT IrpContext,
    IN PBCB Bcb
    )

/*++

Routine Description:

    This routine saves a reference to the bcb in the irp context. This will
    have the affect of keeping the page in memory until we complete the
    request

Arguments:

    Bcb - Supplies the Bcb being referenced

Return Value:

    None.

--*/

{
    PREPINNED_BCBS Repinned;
    ULONG i;

    DebugTrace(+1, Dbg, "FatRepinBcb\n", 0 );
    DebugTrace( 0, Dbg, "IrpContext = %08lx\n", IrpContext );
    DebugTrace( 0, Dbg, "Bcb        = %08lx\n", Bcb );

    //
    //  The algorithm is to search the list of repinned records until
    //  we either find a match for the bcb or we find a null slot.
    //

    Repinned = &IrpContext->Repinned;

    while (TRUE) {

        //
        //  For every entry in the repinned record check if the bcb's
        //  match or if the entry is null.  If the bcb's match then
        //  we've done because we've already repinned this bcb, if
        //  the entry is null then we know, because it's densely packed,
        //  that the bcb is not in the list so add it to the repinned
        //  record and repin it.
        //

        for (i = 0; i < REPINNED_BCBS_ARRAY_SIZE; i += 1) {

            if (Repinned->Bcb[i] == Bcb) {

                DebugTrace(-1, Dbg, "FatRepinBcb -> VOID\n", 0 );
                return;
            }

            if (Repinned->Bcb[i] == NULL) {

                Repinned->Bcb[i] = Bcb;
                CcRepinBcb( Bcb );

                DebugTrace(-1, Dbg, "FatRepinBcb -> VOID\n", 0 );
                return;
            }
        }

        //
        //  We finished checking one repinned record so now locate the next
        //  repinned record,  If there isn't one then allocate and zero out
        //  a new one.
        //

        if (Repinned->Next == NULL) {

            Repinned->Next = FsRtlAllocatePool( PagedPool, sizeof(REPINNED_BCBS) );
            RtlZeroMemory( Repinned->Next, sizeof(REPINNED_BCBS) );
        }

        Repinned = Repinned->Next;
    }
}


VOID
FatUnpinRepinnedBcbs (
    IN PIRP_CONTEXT IrpContext
    )

/*++

Routine Description:

    This routine frees all of the repinned bcbs, stored in an IRP context.

Arguments:

Return Value:

    None.

--*/

{
    IO_STATUS_BLOCK RaiseIosb;
    PREPINNED_BCBS Repinned;
    BOOLEAN WriteThroughToDisk;
    PFILE_OBJECT FileObject = NULL;
    BOOLEAN ForceVerify = FALSE;
    ULONG i;

    DebugTrace(+1, Dbg, "FatUnpinRepinnedBcbs\n", 0 );
    DebugTrace( 0, Dbg, "IrpContext = %08lx\n", IrpContext );

    //
    //  The algorithm for this procedure is to scan the entire list of
    //  repinned records unpinning any repinned bcbs.  We start off
    //  with the first record in the irp context, and while there is a
    //  record to scan we do the following loop.
    //

    Repinned = &IrpContext->Repinned;
    RaiseIosb.Status = STATUS_SUCCESS;

    //
    //  If the request is write through, or the media is removeable,
    //  unpin the bcb's write through.
    //

    WriteThroughToDisk = (BOOLEAN) (FlagOn(IrpContext->Flags, IRP_CONTEXT_FLAG_WRITE_THROUGH) ||
                                    FlagOn(IrpContext->Flags, IRP_CONTEXT_FLAG_FLOPPY));

    while (Repinned != NULL) {

        //
        //  For every non-null entry in the repinned record unpin the
        //  repinned entry.
        //
        //  If the this is removeable media (therefore all requests write-
        //  through) and the write fails, purge the cache so that we throw
        //  away the modifications as we will be returning an error to the
        //  user.
        //

        for (i = 0; i < REPINNED_BCBS_ARRAY_SIZE; i += 1) {

            if (Repinned->Bcb[i] != NULL) {

                IO_STATUS_BLOCK Iosb;

                if ( FlagOn(IrpContext->Flags, IRP_CONTEXT_FLAG_FLOPPY) ) {

                    FileObject = CcGetFileObjectFromBcb( Repinned->Bcb[i] );
                }

                CcUnpinRepinnedBcb( Repinned->Bcb[i],
                                    WriteThroughToDisk,
                                    &Iosb );

                if ( !NT_SUCCESS(Iosb.Status) ) {

                    if (RaiseIosb.Status == STATUS_SUCCESS) {

                        RaiseIosb = Iosb;
                    }

                    //
                    //  If this was a floppy, purge the cache, except for
                    //  Irp major codes that either don't handle the
                    //  error paths correctly or are simple victims like
                    //  cleanup.c.
                    //

                    if (FlagOn(IrpContext->Flags, IRP_CONTEXT_FLAG_FLOPPY) &&
                        (IrpContext->MajorFunction != IRP_MJ_CLEANUP) &&
                        (IrpContext->MajorFunction != IRP_MJ_FLUSH_BUFFERS) &&
                        (IrpContext->MajorFunction != IRP_MJ_SET_INFORMATION)) {

                        CcPurgeCacheSection( FileObject->SectionObjectPointer,
                                             NULL,
                                             0,
                                             FALSE );

                        //
                        //  Force a verify operation here since who knows
                        //  what state things are in.
                        //

                        ForceVerify = TRUE;
                    }
                }

                Repinned->Bcb[i] = NULL;

            } else {

                break;
            }
        }

        //
        //  Now find the next repinned record in the list, and possibly
        //  delete the one we've just processed.
        //

        if (Repinned != &IrpContext->Repinned) {

            PREPINNED_BCBS Saved;

            Saved = Repinned->Next;
            ExFreePool( Repinned );
            Repinned = Saved;

        } else {

            Repinned = Repinned->Next;
            IrpContext->Repinned.Next = NULL;
        }
    }

    //
    //  Now if we weren't completely successful in the our unpin
    //  then raise the iosb we got
    //

    if (!NT_SUCCESS(RaiseIosb.Status)) {

        if (ForceVerify && FileObject) {

            SetFlag(FileObject->DeviceObject->Flags, DO_VERIFY_VOLUME);

            IoSetHardErrorOrVerifyDevice( IrpContext->OriginatingIrp,
                                          FileObject->DeviceObject );
        }

        IrpContext->OriginatingIrp->IoStatus = RaiseIosb;
        FatNormalizeAndRaiseStatus( IrpContext, RaiseIosb.Status );
    }

    DebugTrace(-1, Dbg, "FatUnpinRepinnedBcbs -> VOID\n", 0 );

    return;
}


FINISHED
FatZeroData (
    IN PIRP_CONTEXT IrpContext,
    IN PVCB Vcb,
    IN PFILE_OBJECT FileObject,
    IN ULONG StartingZero,
    IN ULONG ByteCount
    )

/*++

    **** Temporary function - Remove when CcZeroData is capable of handling
    non sector aligned requests.

--*/
{
    LARGE_INTEGER ZeroStart = {0,0};
    LARGE_INTEGER BeyondZeroEnd = {0,0};

    ULONG SectorSize;

    BOOLEAN Finished;

    SectorSize = (ULONG)Vcb->Bpb.BytesPerSector;

    ZeroStart.LowPart = (StartingZero + (SectorSize - 1)) & ~(SectorSize - 1);

    BeyondZeroEnd.LowPart = (StartingZero + ByteCount + (SectorSize - 1))
                            & ~(SectorSize - 1);

    //
    //  If we were called to just zero part of a sector we are screwed.
    //

    if ( ZeroStart.LowPart == BeyondZeroEnd.LowPart ) {

        return TRUE;
    }

    Finished = CcZeroData( FileObject,
                           &ZeroStart,
                           &BeyondZeroEnd,
                           BooleanFlagOn(IrpContext->Flags, IRP_CONTEXT_FLAG_WAIT) );

    return Finished;
}


NTSTATUS
FatCompleteMdl (
    IN PIRP_CONTEXT IrpContext,
    IN PIRP Irp
    )

/*++

Routine Description:

    This routine performs the function of completing Mdl read and write
    requests.  It should be called only from FatFsdRead and FatFsdWrite.

Arguments:

    Irp - Supplies the originating Irp.

Return Value:

    NTSTATUS - Will always be STATUS_PENDING or STATUS_SUCCESS.

--*/

{
    PFILE_OBJECT FileObject;
    PIO_STACK_LOCATION IrpSp;

    DebugTrace(+1, Dbg, "FatCompleteMdl\n", 0 );
    DebugTrace( 0, Dbg, "IrpContext = %08lx\n", IrpContext );
    DebugTrace( 0, Dbg, "Irp        = %08lx\n", Irp );

    //
    // Do completion processing.
    //

    FileObject = IoGetCurrentIrpStackLocation( Irp )->FileObject;

    switch( IrpContext->MajorFunction ) {

    case IRP_MJ_READ:

        CcMdlReadComplete( FileObject, Irp->MdlAddress );
        break;

    case IRP_MJ_WRITE:

        IrpSp = IoGetCurrentIrpStackLocation( Irp );

        ASSERT( FlagOn(IrpContext->Flags, IRP_CONTEXT_FLAG_WAIT ));

        CcMdlWriteComplete( FileObject, &IrpSp->Parameters.Write.ByteOffset, Irp->MdlAddress );

        Irp->IoStatus.Status = STATUS_SUCCESS;

        break;

    default:

        DebugTrace( DEBUG_TRACE_ERROR, 0, "Illegal Mdl Complete.\n", 0);
        FatBugCheck( IrpContext->MajorFunction, 0, 0 );
    }

    //
    // Mdl is now deallocated.
    //

    Irp->MdlAddress = NULL;

    //
    // Complete the request and exit right away.
    //

    FatCompleteRequest( IrpContext, Irp, STATUS_SUCCESS );

    DebugTrace(-1, Dbg, "FatCompleteMdl -> STATUS_SUCCESS\n", 0 );

    return STATUS_SUCCESS;
}

VOID
FatSyncUninitializeCacheMap (
    IN PIRP_CONTEXT IrpContext,
    IN PFILE_OBJECT FileObject
    )

/*++

Routine Description:

    The routine performs a CcUnitializeCacheMap to LargeZero synchronously.  That
    is it waits on the Cc event.  This call is useful when we want to be certain
    when a close will actually some in.

Return Value:

    None.

--*/

{
    CACHE_UNINITIALIZE_EVENT UninitializeCompleteEvent;
    NTSTATUS WaitStatus;

    KeInitializeEvent( &UninitializeCompleteEvent.Event,
                       SynchronizationEvent,
                       FALSE);

    CcUninitializeCacheMap( FileObject,
                            &FatLargeZero,
                            &UninitializeCompleteEvent );

    //
    //  Now wait for the cache manager to finish purging the file.
    //  This will garentee that Mm gets the purge before we
    //  delete the Vcb.
    //

    WaitStatus = KeWaitForSingleObject( &UninitializeCompleteEvent.Event,
                                        Executive,
                                        KernelMode,
                                        FALSE,
                                        NULL);

    ASSERT (NT_SUCCESS(WaitStatus));
}

VOID
FatPinMappedData (
    IN PIRP_CONTEXT IrpContext,
    IN PDCB Dcb,
    IN VBO StartingVbo,
    IN ULONG ByteCount,
    OUT PBCB *Bcb
    )

/*++

Routine Description:

    This routine pins data that was previously mapped before setting it dirty.

Arguments:

    Dcb - Pointer to the DCB for the directory

    StartingVbo - The virtual offset of the first desired byte

    ByteCount - Number of bytes desired

    Bcb - Returns a pointer to the BCB which is valid until unpinned

--*/

{
    LARGE_INTEGER Vbo;

    DebugTrace(+1, Dbg, "FatPinMappedData\n", 0);
    DebugTrace( 0, Dbg, "Dcb         = %08lx\n", Dcb);
    DebugTrace( 0, Dbg, "StartingVbo = %08lx\n", StartingVbo);
    DebugTrace( 0, Dbg, "ByteCount   = %08lx\n", ByteCount);

    //
    //  Call the Cache manager to perform the operation.
    //

    Vbo.QuadPart = StartingVbo;

    if (!CcPinMappedData( Dcb->Specific.Dcb.DirectoryFile,
                          &Vbo,
                          ByteCount,
                          BooleanFlagOn(IrpContext->Flags, IRP_CONTEXT_FLAG_WAIT),
                          Bcb )) {

        //
        // Could not pin the data without waiting (cache miss).
        //

        FatRaiseStatus( IrpContext, STATUS_CANT_WAIT );
    }

    DebugTrace(-1, Dbg, "FatReadDirectoryFile -> VOID, *BCB = %08lx\n", *Bcb);

    return;
}