NTSTATUS
FatCommonRead (
IN PIRP_CONTEXT IrpContext,
IN PIRP Irp
)
/*++
Routine Description:
This is the common read routine for NtReadFile, called from both
the Fsd, or from the Fsp if a request could not be completed without
blocking in the Fsd. This routine has no code where it determines
whether it is running in the Fsd or Fsp. Instead, its actions are
conditionalized by the Wait input parameter, which determines whether
it is allowed to block or not. If a blocking condition is encountered
with Wait == FALSE, however, the request is posted to the Fsp, who
always calls with WAIT == TRUE.
Arguments:
Irp - Supplies the Irp to process
Return Value:
NTSTATUS - The return status for the operation
--*/
{
PVCB Vcb;
PFCB FcbOrDcb;
PCCB Ccb;
VBO StartingVbo;
ULONG ByteCount;
ULONG RequestedByteCount;
PIO_STACK_LOCATION IrpSp;
PFILE_OBJECT FileObject;
TYPE_OF_OPEN TypeOfOpen;
BOOLEAN PostIrp = FALSE;
BOOLEAN OplockPostIrp = FALSE;
BOOLEAN FcbOrDcbAcquired = FALSE;
BOOLEAN Wait;
BOOLEAN PagingIo;
BOOLEAN NonCachedIo;
BOOLEAN SynchronousIo;
NTSTATUS Status;
FAT_IO_CONTEXT StackFatIoContext;
//
// A system buffer is only used if we have to access the
// buffer directly from the Fsp to clear a portion or to
// do a synchronous I/O, or a cached transfer. It is
// possible that our caller may have already mapped a
// system buffer, in which case we must remember this so
// we do not unmap it on the way out.
//
PVOID SystemBuffer = NULL;
LARGE_INTEGER StartingByte;
PAGED_CODE();
//
// Get current Irp stack location.
//
IrpSp = IoGetCurrentIrpStackLocation( Irp );
FileObject = IrpSp->FileObject;
//
// Initialize the appropriate local variables.
//
Wait = BooleanFlagOn(IrpContext->Flags, IRP_CONTEXT_FLAG_WAIT);
PagingIo = BooleanFlagOn(Irp->Flags, IRP_PAGING_IO);
NonCachedIo = BooleanFlagOn(Irp->Flags,IRP_NOCACHE);
SynchronousIo = BooleanFlagOn(FileObject->Flags, FO_SYNCHRONOUS_IO);
DebugTrace(+1, Dbg, "CommonRead\n", 0);
DebugTrace( 0, Dbg, " Irp = %8lx\n", Irp);
DebugTrace( 0, Dbg, " ->ByteCount = %8lx\n", IrpSp->Parameters.Read.Length);
DebugTrace( 0, Dbg, " ->ByteOffset.LowPart = %8lx\n", IrpSp->Parameters.Read.ByteOffset.LowPart);
DebugTrace( 0, Dbg, " ->ByteOffset.HighPart = %8lx\n", IrpSp->Parameters.Read.ByteOffset.HighPart);
//
// Extract starting Vbo and offset.
//
StartingByte = IrpSp->Parameters.Read.ByteOffset;
StartingVbo = StartingByte.LowPart;
ByteCount = IrpSp->Parameters.Read.Length;
RequestedByteCount = ByteCount;
//
// Check for a null request, and return immediately
//
if (ByteCount == 0) {
Irp->IoStatus.Information = 0;
FatCompleteRequest( IrpContext, Irp, STATUS_SUCCESS );
return STATUS_SUCCESS;
}
//
// Extract the nature of the read from the file object, and case on it
//
TypeOfOpen = FatDecodeFileObject(FileObject, &Vcb, &FcbOrDcb, &Ccb);
ASSERT( Vcb != NULL );
//
// Save callers who try to do cached IO to the raw volume from themselves.
//
if (TypeOfOpen == UserVolumeOpen) {
NonCachedIo = TRUE;
}
ASSERT(!(NonCachedIo == FALSE && TypeOfOpen == VirtualVolumeFile));
//
// Collect interesting statistics. The FLAG_USER_IO bit will indicate
// what type of io we're doing in the FatNonCachedIo function.
//
if (PagingIo) {
CollectReadStats(Vcb, TypeOfOpen, ByteCount);
if (TypeOfOpen == UserFileOpen) {
SetFlag(IrpContext->Flags, IRP_CONTEXT_FLAG_USER_IO);
} else {
ClearFlag(IrpContext->Flags, IRP_CONTEXT_FLAG_USER_IO);
}
}
ASSERT(!FlagOn( IrpContext->Flags, IRP_CONTEXT_STACK_IO_CONTEXT ));
//
// Allocate if necessary and initialize a FAT_IO_CONTEXT block for
// all non cached Io. For synchronous Io we use stack storage,
// otherwise we allocate pool.
//
if (NonCachedIo) {
if (IrpContext->FatIoContext == NULL) {
if (!Wait) {
IrpContext->FatIoContext =
FsRtlAllocatePoolWithTag( NonPagedPool,
sizeof(FAT_IO_CONTEXT),
TAG_FAT_IO_CONTEXT );
} else {
IrpContext->FatIoContext = &StackFatIoContext;
SetFlag( IrpContext->Flags, IRP_CONTEXT_STACK_IO_CONTEXT );
}
}
RtlZeroMemory( IrpContext->FatIoContext, sizeof(FAT_IO_CONTEXT) );
if (Wait) {
KeInitializeEvent( &IrpContext->FatIoContext->Wait.SyncEvent,
NotificationEvent,
FALSE );
} else {
IrpContext->FatIoContext->Wait.Async.ResourceThreadId =
ExGetCurrentResourceThread();
IrpContext->FatIoContext->Wait.Async.RequestedByteCount =
ByteCount;
IrpContext->FatIoContext->Wait.Async.FileObject = FileObject;
}
}
//
// These two cases correspond to either a general opened volume, ie.
// open ("a:"), or a read of the volume file (boot sector + fat(s))
//
if ((TypeOfOpen == VirtualVolumeFile) ||
(TypeOfOpen == UserVolumeOpen)) {
LBO StartingLbo;
StartingLbo = StartingByte.QuadPart;
DebugTrace(0, Dbg, "Type of read is User Volume or virtual volume file\n", 0);
if (TypeOfOpen == UserVolumeOpen) {
//
// Verify that the volume for this handle is still valid
//
//
// Verify that the volume for this handle is still valid, permitting
// operations to proceed on dismounted volumes via the handle which
// performed the dismount.
//
if (!FlagOn( Ccb->Flags, CCB_FLAG_COMPLETE_DISMOUNT | CCB_FLAG_SENT_FORMAT_UNIT )) {
FatQuickVerifyVcb( IrpContext, Vcb );
}
//
// If the caller previously sent a format unit command, then we will allow
// their read/write requests to ignore the verify flag on the device, since some
// devices send a media change event after format unit, but we don't want to
// process it yet since we're probably in the process of formatting the
// media.
//
if (FlagOn( Ccb->Flags, CCB_FLAG_SENT_FORMAT_UNIT )) {
SetFlag( IrpContext->Flags, IRP_CONTEXT_FLAG_OVERRIDE_VERIFY );
}
if (!FlagOn( Ccb->Flags, CCB_FLAG_DASD_FLUSH_DONE )) {
(VOID)ExAcquireResourceExclusiveLite( &Vcb->Resource, TRUE );
try {
//
// If the volume isn't locked, flush it.
//
if (!FlagOn(Vcb->VcbState, VCB_STATE_FLAG_LOCKED)) {
FatFlushVolume( IrpContext, Vcb, Flush );
}
} finally {
ExReleaseResourceLite( &Vcb->Resource );
}
SetFlag( Ccb->Flags, CCB_FLAG_DASD_FLUSH_DONE );
}
if (!FlagOn( Ccb->Flags, CCB_FLAG_ALLOW_EXTENDED_DASD_IO )) {
LBO VolumeSize;
//
// Make sure we don't try to read past end of volume,
// reducing the byte count if necessary.
//
VolumeSize = (LBO) Vcb->Bpb.BytesPerSector *
(Vcb->Bpb.Sectors != 0 ? Vcb->Bpb.Sectors :
Vcb->Bpb.LargeSectors);
if (StartingLbo >= VolumeSize) {
Irp->IoStatus.Information = 0;
FatCompleteRequest( IrpContext, Irp, STATUS_END_OF_FILE );
return STATUS_END_OF_FILE;
}
if (ByteCount > VolumeSize - StartingLbo) {
ByteCount = RequestedByteCount = (ULONG) (VolumeSize - StartingLbo);
//
// For async reads we had set the byte count in the FatIoContext
// above, so fix that here.
//
if (!Wait) {
IrpContext->FatIoContext->Wait.Async.RequestedByteCount =
ByteCount;
}
}
}
//
// For DASD we have to probe and lock the user's buffer
//
FatLockUserBuffer( IrpContext, Irp, IoWriteAccess, ByteCount );
} else {
__drv_mustHoldCriticalRegion
NTSTATUS
FatCommonShutdown (
IN PIRP_CONTEXT IrpContext,
IN PIRP Irp
)
/*++
Routine Description:
This is the common routine for shutdown called by both the fsd and
fsp threads.
Arguments:
Irp - Supplies the Irp being processed
Return Value:
NTSTATUS - The return status for the operation
--*/
{
KEVENT Event;
PLIST_ENTRY Links;
PVCB Vcb;
PIRP NewIrp;
IO_STATUS_BLOCK Iosb;
BOOLEAN VcbDeleted;
PAGED_CODE();
//
// Make sure we don't get any pop-ups, and write everything through.
//
SetFlag(IrpContext->Flags, IRP_CONTEXT_FLAG_DISABLE_POPUPS |
IRP_CONTEXT_FLAG_WRITE_THROUGH);
//
// Initialize an event for doing calls down to
// our target device objects.
//
KeInitializeEvent( &Event, NotificationEvent, FALSE );
//
// Indicate that shutdown has started. This is used in FatFspClose.
//
FatData.ShutdownStarted = TRUE;
//
// Get everyone else out of the way
//
ASSERT( FlagOn(IrpContext->Flags, IRP_CONTEXT_FLAG_WAIT) );
#pragma prefast( push )
#pragma prefast( disable: 28137, "prefast wants the wait to be a constant, but that isn't possible for the way fastfat is designed" )
#pragma prefast( disable: 28193, "this will always wait" )
(VOID) FatAcquireExclusiveGlobal( IrpContext );
#pragma prefast( pop )
try {
//
// For every volume that is mounted we will flush the
// volume and then shutdown the target device objects.
//
Links = FatData.VcbQueue.Flink;
while (Links != &FatData.VcbQueue) {
Vcb = CONTAINING_RECORD(Links, VCB, VcbLinks);
Links = Links->Flink;
//
// If we have already been called before for this volume
// (and yes this does happen), skip this volume as no writes
// have been allowed since the first shutdown.
//
if ( FlagOn( Vcb->VcbState, VCB_STATE_FLAG_SHUTDOWN) ||
(Vcb->VcbCondition != VcbGood) ) {
continue;
}
FatAcquireExclusiveVolume( IrpContext, Vcb );
try {
(VOID)FatFlushVolume( IrpContext, Vcb, Flush );
//
// The volume is now clean, note it. We purge the
// volume file cache map before marking the volume
// clean incase there is a stale Bpb in the cache.
//
if (!FlagOn(Vcb->VcbState, VCB_STATE_FLAG_MOUNTED_DIRTY)) {
CcPurgeCacheSection( &Vcb->SectionObjectPointers,
NULL,
0,
FALSE );
FatMarkVolume( IrpContext, Vcb, VolumeClean );
}
} except( EXCEPTION_EXECUTE_HANDLER ) {
FatResetExceptionState( IrpContext );
}
//
// Sometimes we take an excepion while flushing the volume, such
// as when autoconv has converted the volume and is rebooting.
// Even in that case we want to send the shutdown irp to the
// target device so it can know to flush its cache, if it has one.
//
try {
NewIrp = IoBuildSynchronousFsdRequest( IRP_MJ_SHUTDOWN,
Vcb->TargetDeviceObject,
NULL,
0,
NULL,
&Event,
&Iosb );
if (NewIrp != NULL) {
if (NT_SUCCESS(IoCallDriver( Vcb->TargetDeviceObject, NewIrp ))) {
(VOID) KeWaitForSingleObject( &Event,
Executive,
KernelMode,
FALSE,
NULL );
KeClearEvent( &Event );
}
}
} except( EXCEPTION_EXECUTE_HANDLER ) {
FatResetExceptionState( IrpContext );
}
SetFlag( Vcb->VcbState, VCB_STATE_FLAG_SHUTDOWN );
//
// Attempt to punch the volume down.
//
VcbDeleted = FatCheckForDismount( IrpContext,
Vcb,
FALSE );
if (!VcbDeleted) {
#pragma prefast( suppress:28107, "prefast is having trouble figuring out that Vcb is acquired" )
FatReleaseVolume( IrpContext, Vcb );
}
}
} finally {
FatReleaseGlobal( IrpContext );
//
// Unregister the file system.
//
IoUnregisterFileSystem( FatDiskFileSystemDeviceObject);
IoUnregisterFileSystem( FatCdromFileSystemDeviceObject);
IoDeleteDevice( FatDiskFileSystemDeviceObject);
IoDeleteDevice( FatCdromFileSystemDeviceObject);
FatCompleteRequest( IrpContext, Irp, STATUS_SUCCESS );
}
//
// And return to our caller
//
DebugTrace(-1, Dbg, "FatFsdShutdown -> STATUS_SUCCESS\n", 0);
return STATUS_SUCCESS;
}
NTSTATUS
NdFatCommonFlushBuffers (
IN PIRP_CONTEXT IrpContext,
IN PIRP Irp
)
/*++
Routine Description:
This is the common routine for flushing a buffer.
Arguments:
Irp - Supplies the Irp to process
Return Value:
NTSTATUS - The return status for the operation
--*/
{
NTSTATUS Status;
PIO_STACK_LOCATION IrpSp;
PFILE_OBJECT FileObject;
TYPE_OF_OPEN TypeOfOpen;
PVCB Vcb;
PFCB Fcb;
PCCB Ccb;
BOOLEAN VcbAcquired = FALSE;
BOOLEAN FcbAcquired = FALSE;
PDIRENT Dirent;
PBCB DirentBcb = NULL;
PVOLUME_DEVICE_OBJECT volDo = CONTAINING_RECORD( IrpContext->Vcb, VOLUME_DEVICE_OBJECT, Vcb );
BOOLEAN secondarySessionResourceAcquired = FALSE;
PSECONDARY_REQUEST secondaryRequest = NULL;
PNDFS_REQUEST_HEADER ndfsRequestHeader;
PNDFS_WINXP_REQUEST_HEADER ndfsWinxpRequestHeader;
PNDFS_WINXP_REPLY_HEADER ndfsWinxpReplytHeader;
LARGE_INTEGER timeOut;
PAGED_CODE();
IrpSp = IoGetCurrentIrpStackLocation( Irp );
DebugTrace(+1, Dbg, "FatCommonFlushBuffers\n", 0);
DebugTrace( 0, Dbg, "Irp = %08lx\n", Irp);
DebugTrace( 0, Dbg, "->FileObject = %08lx\n", IrpSp->FileObject);
//
// Extract and decode the file object
//
FileObject = IrpSp->FileObject;
TypeOfOpen = FatDecodeFileObject( FileObject, &Vcb, &Fcb, &Ccb );
//
// CcFlushCache is always synchronous, so if we can't wait enqueue
// the irp to the Fsp.
//
if ( !FlagOn(IrpContext->Flags, IRP_CONTEXT_FLAG_WAIT) ) {
Status = FatFsdPostRequest( IrpContext, Irp );
DebugTrace(-1, Dbg, "FatCommonFlushBuffers -> %08lx\n", Status );
return Status;
}
Status = STATUS_SUCCESS;
try {
if (!FlagOn(Ccb->NdFatFlags, ND_FAT_CCB_FLAG_UNOPENED)) {
do {
secondarySessionResourceAcquired
= SecondaryAcquireResourceExclusiveLite( IrpContext,
&volDo->Secondary->SessionResource,
BooleanFlagOn(IrpContext->Flags, IRP_CONTEXT_FLAG_WAIT) );
if (FlagOn(volDo->Secondary->Thread.Flags, SECONDARY_THREAD_FLAG_REMOTE_DISCONNECTED) ) {
PrintIrp( Dbg2, "SECONDARY_THREAD_FLAG_REMOTE_DISCONNECTED", NULL, IrpContext->OriginatingIrp );
FatRaiseStatus( IrpContext, STATUS_CANT_WAIT );
}
secondaryRequest = ALLOC_WINXP_SECONDARY_REQUEST( volDo->Secondary, IRP_MJ_FLUSH_BUFFERS, 0 );
if (secondaryRequest == NULL) {
Status = STATUS_INSUFFICIENT_RESOURCES;
break;
}
ndfsRequestHeader = &secondaryRequest->NdfsRequestHeader;
INITIALIZE_NDFS_REQUEST_HEADER( ndfsRequestHeader, NDFS_COMMAND_EXECUTE, volDo->Secondary, IRP_MJ_FLUSH_BUFFERS, 0 );
ndfsWinxpRequestHeader = (PNDFS_WINXP_REQUEST_HEADER)(ndfsRequestHeader+1);
ASSERT( ndfsWinxpRequestHeader == (PNDFS_WINXP_REQUEST_HEADER)secondaryRequest->NdfsRequestData );
INITIALIZE_NDFS_WINXP_REQUEST_HEADER( ndfsWinxpRequestHeader,
IrpContext->OriginatingIrp,
IoGetCurrentIrpStackLocation(IrpContext->OriginatingIrp),
Ccb->PrimaryFileHandle );
ASSERT( !ExIsResourceAcquiredSharedLite(&IrpContext->Vcb->Resource) );
secondaryRequest->RequestType = SECONDARY_REQ_SEND_MESSAGE;
QueueingSecondaryRequest( volDo->Secondary, secondaryRequest );
timeOut.QuadPart = -NDFAT_TIME_OUT;
Status = KeWaitForSingleObject( &secondaryRequest->CompleteEvent, Executive, KernelMode, FALSE, &timeOut );
if (Status != STATUS_SUCCESS) {
ASSERT( NDFAT_BUG );
break;
}
KeClearEvent (&secondaryRequest->CompleteEvent);
if (BooleanFlagOn(volDo->Secondary->Thread.Flags, SECONDARY_THREAD_FLAG_REMOTE_DISCONNECTED)) {
FatRaiseStatus( IrpContext, STATUS_CANT_WAIT );
}
if (secondaryRequest->ExecuteStatus == STATUS_SUCCESS) {
ndfsWinxpReplytHeader = (PNDFS_WINXP_REPLY_HEADER)secondaryRequest->NdfsReplyData;
ASSERT(ndfsWinxpReplytHeader->Status == STATUS_SUCCESS);
}
if (secondaryRequest) {
DereferenceSecondaryRequest( secondaryRequest );
secondaryRequest = NULL;
}
if ( secondarySessionResourceAcquired == TRUE ) {
SecondaryReleaseResourceLite( IrpContext, &volDo->Secondary->SessionResource );
secondarySessionResourceAcquired = FALSE;
}
break;
} while(0);
}
Status = STATUS_SUCCESS;
//
// Case on the type of open that we are trying to flush
//
switch (TypeOfOpen) {
case VirtualVolumeFile:
case EaFile:
case DirectoryFile:
DebugTrace(0, Dbg, "Flush that does nothing\n", 0);
break;
case UserFileOpen:
DebugTrace(0, Dbg, "Flush User File Open\n", 0);
(VOID)FatAcquireExclusiveFcb( IrpContext, Fcb );
FcbAcquired = TRUE;
FatVerifyFcb( IrpContext, Fcb );
//
// If the file is cached then flush its cache
//
Status = FatFlushFile( IrpContext, Fcb, Flush );
//
// Also update and flush the file's dirent in the parent directory if the
// file flush worked.
//
if (NT_SUCCESS( Status )) {
//
// Insure that we get the filesize to disk correctly. This is
// benign if it was already good.
//
// (why do we need to do this?)
//
SetFlag(FileObject->Flags, FO_FILE_SIZE_CHANGED);
#if 0
FatUpdateDirentFromFcb( IrpContext, FileObject, Fcb, Ccb );
#endif
//
// Flush the volume file to get any allocation information
// updates to disk.
//
if (FlagOn(Fcb->FcbState, FCB_STATE_FLUSH_FAT)) {
Status = FatFlushFat( IrpContext, Vcb );
ClearFlag(Fcb->FcbState, FCB_STATE_FLUSH_FAT);
}
//
// Set the write through bit so that these modifications
// will be completed with the request.
//
SetFlag(IrpContext->Flags, IRP_CONTEXT_FLAG_WRITE_THROUGH);
}
break;
case UserDirectoryOpen:
//
// If the user had opened the root directory then we'll
// oblige by flushing the volume.
//
if (NodeType(Fcb) != FAT_NTC_ROOT_DCB) {
DebugTrace(0, Dbg, "Flush a directory does nothing\n", 0);
break;
}
case UserVolumeOpen:
DebugTrace(0, Dbg, "Flush User Volume Open, or root dcb\n", 0);
//
// Acquire exclusive access to the Vcb.
//
{
BOOLEAN Finished;
Finished = FatAcquireExclusiveSecondaryVcb( IrpContext, Vcb );
ASSERT( Finished );
}
VcbAcquired = TRUE;
//
// Mark the volume clean and then flush the volume file,
// and then all directories
//
Status = FatFlushVolume( IrpContext, Vcb, Flush );
//
// If the volume was dirty, do the processing that the delayed
// callback would have done.
//
if (FlagOn(Vcb->VcbState, VCB_STATE_FLAG_VOLUME_DIRTY)) {
//
// Cancel any pending clean volumes.
//
(VOID)KeCancelTimer( &Vcb->CleanVolumeTimer );
(VOID)KeRemoveQueueDpc( &Vcb->CleanVolumeDpc );
//
// The volume is now clean, note it.
//
if (!FlagOn(Vcb->VcbState, VCB_STATE_FLAG_MOUNTED_DIRTY)) {
FatMarkVolume( IrpContext, Vcb, VolumeClean );
ClearFlag( Vcb->VcbState, VCB_STATE_FLAG_VOLUME_DIRTY );
}
//
// Unlock the volume if it is removable.
//
if (FlagOn(Vcb->VcbState, VCB_STATE_FLAG_REMOVABLE_MEDIA) &&
!FlagOn(Vcb->VcbState, VCB_STATE_FLAG_BOOT_OR_PAGING_FILE)) {
FatToggleMediaEjectDisable( IrpContext, Vcb, FALSE );
}
}
break;
default:
FatBugCheck( TypeOfOpen, 0, 0 );
}
FatUnpinBcb( IrpContext, DirentBcb );
FatUnpinRepinnedBcbs( IrpContext );
} finally {
DebugUnwind( FatCommonFlushBuffers );
if (secondaryRequest)
DereferenceSecondaryRequest( secondaryRequest );
if (secondarySessionResourceAcquired) {
SecondaryReleaseResourceLite( IrpContext, &volDo->Secondary->SessionResource );
}
FatUnpinBcb( IrpContext, DirentBcb );
if (VcbAcquired) { FatReleaseSecondaryVcb( IrpContext, Vcb ); }
if (FcbAcquired) { FatReleaseFcb( IrpContext, Fcb ); }
//
// If this is a normal termination then pass the request on
// to the target device object.
//
if (!AbnormalTermination()) {
NTSTATUS DriverStatus;
PIO_STACK_LOCATION NextIrpSp;
//
// Get the next stack location, and copy over the stack location
//
NextIrpSp = IoGetNextIrpStackLocation( Irp );
*NextIrpSp = *IrpSp;
//
// Set up the completion routine
//
IoSetCompletionRoutine( Irp,
FatFlushCompletionRoutine,
ULongToPtr( Status ),
TRUE,
TRUE,
TRUE );
//
// Send the request.
//
DriverStatus = IoCallDriver(Vcb->TargetDeviceObject, Irp);
Status = (DriverStatus == STATUS_INVALID_DEVICE_REQUEST) ?
Status : DriverStatus;
//
// Free the IrpContext and return to the caller.
//
FatCompleteRequest( IrpContext, FatNull, STATUS_SUCCESS );
}
DebugTrace(-1, Dbg, "FatCommonFlushBuffers -> %08lx\n", Status);
}
return Status;
}
NTSTATUS
FatCommonRead (
IN PIRP_CONTEXT IrpContext,
IN PIRP Irp
)
/*++
Routine Description:
This is the common read routine for NtReadFile, called from both
the Fsd, or from the Fsp if a request could not be completed without
blocking in the Fsd. This routine has no code where it determines
whether it is running in the Fsd or Fsp. Instead, its actions are
conditionalized by the Wait input parameter, which determines whether
it is allowed to block or not. If a blocking condition is encountered
with Wait == FALSE, however, the request is posted to the Fsp, who
always calls with WAIT == TRUE.
Arguments:
Irp - Supplies the Irp to process
Return Value:
NTSTATUS - The return status for the operation
--*/
{
PVCB Vcb;
PFCB FcbOrDcb;
PCCB Ccb;
VBO StartingVbo;
ULONG ByteCount;
ULONG RequestedByteCount;
PIO_STACK_LOCATION IrpSp;
PFILE_OBJECT FileObject;
TYPE_OF_OPEN TypeOfRead;
BOOLEAN PostIrp = FALSE;
BOOLEAN OplockPostIrp = FALSE;
BOOLEAN FcbOrDcbAcquired = FALSE;
BOOLEAN Wait;
BOOLEAN PagingIo;
BOOLEAN NonCachedIo;
BOOLEAN SynchronousIo;
NTSTATUS Status;
FAT_IO_CONTEXT StackFatIoContext;
//
// A system buffer is only used if we have to access the
// buffer directly from the Fsp to clear a portion or to
// do a synchronous I/O, or a cached transfer. It is
// possible that our caller may have already mapped a
// system buffer, in which case we must remember this so
// we do not unmap it on the way out.
//
PVOID SystemBuffer = NULL;
LARGE_INTEGER StartingByte;
//
// Get current Irp stack location.
//
IrpSp = IoGetCurrentIrpStackLocation( Irp );
FileObject = IrpSp->FileObject;
//
// Initialize the appropriate local variables.
//
Wait = BooleanFlagOn(IrpContext->Flags, IRP_CONTEXT_FLAG_WAIT);
PagingIo = BooleanFlagOn(Irp->Flags, IRP_PAGING_IO);
NonCachedIo = BooleanFlagOn(Irp->Flags,IRP_NOCACHE);
SynchronousIo = BooleanFlagOn(FileObject->Flags, FO_SYNCHRONOUS_IO);
DebugTrace(+1, Dbg, "CommonRead\n", 0);
DebugTrace( 0, Dbg, " Irp = %8lx\n", Irp);
DebugTrace( 0, Dbg, " ->ByteCount = %8lx\n", IrpSp->Parameters.Read.Length);
DebugTrace( 0, Dbg, " ->ByteOffset.LowPart = %8lx\n", IrpSp->Parameters.Read.ByteOffset.LowPart);
DebugTrace( 0, Dbg, " ->ByteOffset.HighPart = %8lx\n", IrpSp->Parameters.Read.ByteOffset.HighPart);
//
// Extract starting Vbo and offset.
//
StartingByte = IrpSp->Parameters.Read.ByteOffset;
StartingVbo = StartingByte.LowPart;
ByteCount = IrpSp->Parameters.Read.Length;
RequestedByteCount = ByteCount;
//
// Check for a null request, and return immediately
//
if (ByteCount == 0) {
Irp->IoStatus.Information = 0;
FatCompleteRequest( IrpContext, Irp, STATUS_SUCCESS );
return STATUS_SUCCESS;
}
//
// Check for a non-zero high part offset
//
if ( StartingByte.HighPart != 0 ) {
Irp->IoStatus.Information = 0;
FatCompleteRequest( IrpContext, Irp, STATUS_END_OF_FILE );
return STATUS_END_OF_FILE;
}
//
// Extract the nature of the read from the file object, and case on it
//
TypeOfRead = FatDecodeFileObject(FileObject, &Vcb, &FcbOrDcb, &Ccb);
//
// Collect interesting statistics. The FLAG_USER_IO bit will indicate
// what type of io we're doing in the FatNonCachedIo function.
//
if (PagingIo) {
CollectReadStats(Vcb, TypeOfRead, ByteCount);
if (TypeOfRead == UserFileOpen) {
SetFlag(IrpContext->Flags, IRP_CONTEXT_FLAG_USER_IO);
} else {
ClearFlag(IrpContext->Flags, IRP_CONTEXT_FLAG_USER_IO);
}
}
//
// If there is a previous STACK FatIoContext pointer, NULL it.
//
if ((IrpContext->FatIoContext != NULL) &&
FlagOn(IrpContext->Flags, IRP_CONTEXT_STACK_IO_CONTEXT)) {
IrpContext->FatIoContext = NULL;
}
//
// Allocate if necessary and initialize a FAT_IO_CONTEXT block for
// all non cached Io, except Cvf file Io. For synchronous Io
// we use stack storage, otherwise we allocate pool.
//
if (NonCachedIo &&
!(FcbOrDcb && FlagOn(FcbOrDcb->FcbState,
FCB_STATE_COMPRESSED_VOLUME_FILE))) {
if (IrpContext->FatIoContext == NULL) {
if (!Wait) {
IrpContext->FatIoContext =
FsRtlAllocatePool( NonPagedPool, sizeof(FAT_IO_CONTEXT) );
} else {
IrpContext->FatIoContext = &StackFatIoContext;
SetFlag( IrpContext->Flags, IRP_CONTEXT_STACK_IO_CONTEXT );
}
}
RtlZeroMemory( IrpContext->FatIoContext, sizeof(FAT_IO_CONTEXT) );
if (Wait) {
KeInitializeEvent( &IrpContext->FatIoContext->Wait.SyncEvent,
NotificationEvent,
FALSE );
} else {
IrpContext->FatIoContext->Wait.Async.ResourceThreadId =
ExGetCurrentResourceThread();
IrpContext->FatIoContext->Wait.Async.RequestedByteCount =
ByteCount;
IrpContext->FatIoContext->Wait.Async.FileObject = FileObject;
}
}
//
// These two cases correspond to either a general opened volume, ie.
// open ("a:"), or a read of the volume file (boot sector + fat(s))
//
if ((TypeOfRead == VirtualVolumeFile) ||
(TypeOfRead == UserVolumeOpen)) {
DebugTrace(0, Dbg, "Type of read is User Volume or virtual volume file\n", 0);
if (TypeOfRead == UserVolumeOpen) {
//
// Verify that the volume for this handle is still valid
//
FatQuickVerifyVcb( IrpContext, Vcb );
if (!FlagOn( Ccb->Flags, CCB_FLAG_DASD_FLUSH_DONE )) {
(VOID)ExAcquireResourceExclusive( &Vcb->Resource, TRUE );
try {
//
// If the volume isn't locked, flush it.
//
if (!FlagOn(Vcb->VcbState, VCB_STATE_FLAG_LOCKED)) {
FatFlushVolume( IrpContext, Vcb );
}
}
finally {
ExReleaseResource( &Vcb->Resource );
}
SetFlag( Ccb->Flags, CCB_FLAG_DASD_FLUSH_DONE );
}