deviosup.c

winddk src目录下的文件系统驱动源码压缩!

                KeDelayExecutionThread (KernelMode, FALSE, &Fat30Milliseconds);
            }

            //
            //  Note that since we failed to launch this associated Irp, that the completion
            //  code at the bottom will take care of completing the master Irp.
            //
            
            if (!NT_SUCCESS(Irp->IoStatus.Status)) {

                ASSERT( IrpCount );
                break;
            }

        } else {
                        
            //
            //  Indicate we used an associated Irp.
            //

            IrpCount -= 1;
        }
        
        //
        //  With an associated IRP, we must take over the first stack location so
        //  we can have one to put the completion routine on.  When re-using the
        //  master IRP, its already there.
        //
        
        if (!IrpIsMaster) {
            
            //
            //  Get the first IRP stack location in the associated Irp
            //

            IoSetNextIrpStackLocation( AssocIrp );
            NextIrpSp = IoGetCurrentIrpStackLocation( AssocIrp );

            //
            //  Setup the Stack location to describe our read.
            //

            NextIrpSp->MajorFunction = IrpSp->MajorFunction;
            NextIrpSp->Parameters.Read.Length = NextByteCount;
            NextIrpSp->Parameters.Read.ByteOffset.QuadPart = Vbo;

            //
            //  We also need the VolumeDeviceObject in the Irp stack in case
            //  we take the failure path.
            //

            NextIrpSp->DeviceObject = IrpSp->DeviceObject;
            
        } else {

            //
            //  Save the MDL in the IRP and prepare the stack
            //  context for the completion routine.
            //

            KeInitializeEvent( &Context.Event, SynchronizationEvent, FALSE );
            Context.RestoreMdl = Irp->MdlAddress;
        }

        //
        //  And drop our Mdl into the Irp.
        //

        AssocIrp->MdlAddress = Mdl;

        //
        //  Set up the completion routine address in our stack frame.
        //  For true associated IRPs, this is only invoked on error or
        //  cancel, and just copies the error Status into master irp's
        //  iosb.
        //
        //  If the error implies a media problem, it also enqueues a
        //  worker item to write out the dirty bit so that the next
        //  time we run we will do a autochk /r
        //

        if (IrpIsMaster) {
            
            IoSetCompletionRoutine( AssocIrp,
                                    FatPagingFileCompletionRoutineCatch,
                                    &Context,
                                    TRUE,
                                    TRUE,
                                    TRUE );

        } else {
            
            IoSetCompletionRoutine( AssocIrp,
                                    FatPagingFileCompletionRoutine,
                                    Irp,
                                    FALSE,
                                    TRUE,
                                    TRUE );
        }

        //
        //  Setup the next IRP stack location for the disk driver beneath us.
        //

        NextIrpSp = IoGetNextIrpStackLocation( AssocIrp );

        //
        //  Since this is paging file IO, we'll just ignore the verify bit.
        //

        SetFlag( NextIrpSp->Flags, SL_OVERRIDE_VERIFY_VOLUME );

        //
        //  Setup the Stack location to do a read from the disk driver.
        //

        NextIrpSp->MajorFunction = IrpSp->MajorFunction;
        NextIrpSp->Parameters.Read.Length = NextByteCount;
        NextIrpSp->Parameters.Read.ByteOffset.QuadPart = NextLbo;

        (VOID)IoCallDriver( DeviceObject, AssocIrp );

        //
        //  Wait for the Irp in the catch case and drop the flags.
        //

        if (IrpIsMaster) {
            
            KeWaitForSingleObject( &Context.Event, Executive, KernelMode, FALSE, NULL );
            IrpIsMaster = MdlIsReserve = FALSE;

            //
            //  If the Irp is showing a failed status, there is no point in continuing.
            //  In doing so, we get to avoid squirreling away the failed status in case
            //  we were to re-use the master irp again.
            //
            //  Note that since we re-used the master, we must not have issued the "last"
            //  associated Irp, and thus the completion code at the bottom will take care
            //  of that for us.
            //
            
            if (!NT_SUCCESS(Irp->IoStatus.Status)) {

                ASSERT( IrpCount );
                break;
            }
        }

        //
        //  Now adjust everything for the next pass through the loop.
        //

        Vbo += NextByteCount;
        BufferOffset += NextByteCount;
        ByteCount -= NextByteCount;

        //
        //  Try to lookup the next run, if we are not done and we got
        //  all the way through the current run.
        //

        if (RemainingByteCount) {

            //
            //  Advance the Lbo/Vbo if we have more to do in the current run.
            //
            
            NextLbo += NextByteCount;
            NextVbo += NextByteCount;

            NextByteCount = RemainingByteCount;
        
        } else {
        
            CurrentIndex += 1;

            if ( CurrentIndex <= LastIndex ) {

                ASSERT( ByteCount != 0 );

                FatGetNextMcbEntry( Fcb->Vcb, &Fcb->Mcb,
                                    CurrentIndex,
                                    &NextVbo,
                                    &NextLbo,
                                    &NextByteCount );

                ASSERT( NextVbo == Vbo );
            }
        }
    } // while ( CurrentIndex <= LastIndex )

    //
    //  If we didn't get enough associated Irps going to make this asynchronous, we
    //  twiddle our thumbs and wait for those we did launch to complete.
    //
    
    if (IrpCount) {

        while (Irp->AssociatedIrp.IrpCount != IrpCount) {
            
            KeDelayExecutionThread (KernelMode, FALSE, &Fat30Milliseconds);
        }

        IoCompleteRequest( Irp, IO_DISK_INCREMENT );
    }

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


NTSTATUS
FatNonCachedIo (
    IN PIRP_CONTEXT IrpContext,
    IN PIRP Irp,
    IN PFCB FcbOrDcb,
    IN ULONG StartingVbo,
    IN ULONG ByteCount,
    IN ULONG UserByteCount
    )

/*++

Routine Description:

    This routine performs the non-cached disk io described in its parameters.
    The choice of a single run is made if possible, otherwise multiple runs
    are executed.

Arguments:

    IrpContext->MajorFunction - Supplies either IRP_MJ_READ or IRP_MJ_WRITE.

    Irp - Supplies the requesting Irp.

    FcbOrDcb - Supplies the file to act on.

    StartingVbo - The starting point for the operation.

    ByteCount - The lengh of the operation.
    
    UserByteCount - The last byte the user can see, rest to be zeroed.

Return Value:

    None.

--*/

{
    //
    // Declare some local variables for enumeration through the
    // runs of the file, and an array to store parameters for
    // parallel I/Os
    //

    BOOLEAN Wait;

    LBO NextLbo;
    VBO NextVbo;
    ULONG NextByteCount;
    BOOLEAN NextIsAllocated;

    LBO LastLbo;
    ULONG LastByteCount;
    BOOLEAN LastIsAllocated;

    BOOLEAN EndOnMax;

    ULONG FirstIndex;
    ULONG CurrentIndex;
    ULONG LastIndex;

    ULONG NextRun;
    ULONG BufferOffset;
    ULONG OriginalByteCount;

    IO_RUN StackIoRuns[FAT_MAX_IO_RUNS_ON_STACK];
    PIO_RUN IoRuns;

    DebugTrace(+1, Dbg, "FatNonCachedIo\n", 0);
    DebugTrace( 0, Dbg, "Irp           = %08lx\n", Irp );
    DebugTrace( 0, Dbg, "MajorFunction = %08lx\n", IrpContext->MajorFunction );
    DebugTrace( 0, Dbg, "FcbOrDcb      = %08lx\n", FcbOrDcb );
    DebugTrace( 0, Dbg, "StartingVbo   = %08lx\n", StartingVbo );
    DebugTrace( 0, Dbg, "ByteCount     = %08lx\n", ByteCount );

    if (!FlagOn(Irp->Flags, IRP_PAGING_IO)) {

        PFILE_SYSTEM_STATISTICS Stats =
            &FcbOrDcb->Vcb->Statistics[KeGetCurrentProcessorNumber()];

        if (IrpContext->MajorFunction == IRP_MJ_READ) {
            Stats->Fat.NonCachedReads += 1;
            Stats->Fat.NonCachedReadBytes += ByteCount;
        } else {
            Stats->Fat.NonCachedWrites += 1;
            Stats->Fat.NonCachedWriteBytes += ByteCount;
        }
    }

    //
    //  Initialize some locals.
    //

    NextRun = 0;
    BufferOffset = 0;
    OriginalByteCount = ByteCount;

    Wait = BooleanFlagOn(IrpContext->Flags, IRP_CONTEXT_FLAG_WAIT);

    //
    // For nonbuffered I/O, we need the buffer locked in all
    // cases.
    //
    // This call may raise.  If this call succeeds and a subsequent
    // condition is raised, the buffers are unlocked automatically
    // by the I/O system when the request is completed, via the
    // Irp->MdlAddress field.
    //

    FatLockUserBuffer( IrpContext,
                       Irp,
                       (IrpContext->MajorFunction == IRP_MJ_READ) ?
                       IoWriteAccess : IoReadAccess,
                       ByteCount );

    //
    //  Setup the required zeroing for read requests.
    //

    if (UserByteCount != ByteCount) {

        PMDL Mdl;

        ASSERT( ByteCount > UserByteCount );

        Mdl = IoAllocateMdl( (PUCHAR) Irp->UserBuffer + UserByteCount,
                             ByteCount - UserByteCount,
                             FALSE,
                             FALSE,
                             NULL );

        if (Mdl == NULL) {

            FatRaiseStatus( IrpContext, STATUS_INSUFFICIENT_RESOURCES );
        }

        IoBuildPartialMdl( Irp->MdlAddress,
                           Mdl,
                           (PUCHAR) Irp->UserBuffer + UserByteCount,
                           ByteCount - UserByteCount );

        IrpContext->FatIoContext->ZeroMdl = Mdl;

        //
        //  Map the MDL now so we can't fail at IO completion time.  Note
        //  that this will be only a single page.
        //

        if (MmGetSystemAddressForMdlSafe( Mdl, NormalPagePriority ) == NULL) {

            FatRaiseStatus( IrpContext, STATUS_INSUFFICIENT_RESOURCES );
        }
    }

    //
    //  Try to lookup the first run.  If there is just a single run,
    //  we may just be able to pass it on.
    //

    FatLookupFileAllocation( IrpContext,
                             FcbOrDcb,
                             StartingVbo,
                             &NextLbo,
                             &NextByteCount,
                             &NextIsAllocated,
                             &EndOnMax,
                             &FirstIndex );

    //
    //  We just added the allocation, thus there must be at least
    //  one entry in the mcb corresponding to our write, ie.
    //  NextIsAllocated must be true.  If not, the pre-existing file
    //  must have an allocation error.
    //

    if ( !NextIsAllocated ) {

        FatPopUpFileCorrupt( IrpContext, FcbOrDcb );

        FatRaiseStatus( IrpContext, STATUS_FILE_CORRUPT_ERROR );
    }

    ASSERT( NextByteCount != 0 );

    //
    //  If the request was not aligned correctly, read in the first
    //  part first.
    //


    //
    //  See if the write covers a single valid run, and if so pass
    //  it on.  We must bias this by the byte that is lost at the
    //  end of the maximal file.
    //

    if ( NextByteCount >= ByteCount - (EndOnMax ? 1 : 0)) {

        if (FlagOn(Irp->Flags, IRP_PAGING_IO)) {
            CollectDiskIoStats(FcbOrDcb->Vcb, IrpContext->MajorFunction,
                               FlagOn(IrpContext->Flags, IRP_CONTEXT_FLAG_USER_IO), 1);
        } else {

            PFILE_SYSTEM_STATISTICS Stats =
                &FcbOrDcb->Vcb->Statistics[KeGetCurrentProcessorNumber()];

            if (IrpContext->MajorFunction == IRP_MJ_READ) {
                Stats->Fat.NonCachedDiskReads += 1;
            } else {
                Stats->Fat.NonCachedDiskWrites += 1;
            }
        }

        DebugTrace( 0, Dbg, "Passing 1 Irp on to Disk Driver\n", 0 );

        FatSingleAsync( IrpContext,
                        FcbOrDcb->Vcb,
                        NextLbo,
                        ByteCount,
                        Irp );

    } else {

        //
        //  If there we can't wait, and there are more runs than we can handle,
        //  we will have to post this request.
        //

        FatLookupFileAllocation( IrpContext,
                                 FcbOrDcb,
                                 StartingVbo + ByteCount - 1,
                                 &LastLbo,
                                 &LastByteCount,
                                 &LastIsAllocated,