Leaked source code of windows server 2003
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/*++
Copyright (c) 1989-2000 Microsoft Corporation
Module Name:
ResrcSup.c
Abstract:
This module implements the Cdfs Resource acquisition routines
// @@BEGIN_DDKSPLIT
Author:
Brian Andrew [BrianAn] 01-July-1995
Revision History:
// @@END_DDKSPLIT
--*/
#include "CdProcs.h"
//
// The Bug check file id for this module
//
#define BugCheckFileId (CDFS_BUG_CHECK_RESRCSUP)
#ifdef ALLOC_PRAGMA
#pragma alloc_text(PAGE, CdAcquireForCache)
#pragma alloc_text(PAGE, CdAcquireForCreateSection)
#pragma alloc_text(PAGE, CdAcquireResource)
#pragma alloc_text(PAGE, CdNoopAcquire)
#pragma alloc_text(PAGE, CdNoopRelease)
#pragma alloc_text(PAGE, CdReleaseForCreateSection)
#pragma alloc_text(PAGE, CdReleaseFromCache)
#endif
BOOLEAN
CdAcquireResource (
IN PIRP_CONTEXT IrpContext,
IN PERESOURCE Resource,
IN BOOLEAN IgnoreWait,
IN TYPE_OF_ACQUIRE Type
)
/*++
Routine Description:
This is the single routine used to acquire file system resources. It
looks at the IgnoreWait flag to determine whether to try to acquire the
resource without waiting. Returning TRUE/FALSE to indicate success or
failure. Otherwise it is driven by the WAIT flag in the IrpContext and
will raise CANT_WAIT on a failure.
Arguments:
Resource - This is the resource to try and acquire.
IgnoreWait - If TRUE then this routine will not wait to acquire the
resource and will return a boolean indicating whether the resource was
acquired. Otherwise we use the flag in the IrpContext and raise
if the resource is not acquired.
Type - Indicates how we should try to get the resource.
Return Value:
BOOLEAN - TRUE if the resource is acquired. FALSE if not acquired and
IgnoreWait is specified. Otherwise we raise CANT_WAIT.
--*/
{
BOOLEAN Wait = FALSE;
BOOLEAN Acquired;
PAGED_CODE();
//
// We look first at the IgnoreWait flag, next at the flag in the Irp
// Context to decide how to acquire this resource.
//
if (!IgnoreWait && FlagOn( IrpContext->Flags, IRP_CONTEXT_FLAG_WAIT )) {
Wait = TRUE;
}
//
// Attempt to acquire the resource either shared or exclusively.
//
switch (Type) {
case AcquireExclusive:
Acquired = ExAcquireResourceExclusiveLite( Resource, Wait );
break;
case AcquireShared:
Acquired = ExAcquireResourceSharedLite( Resource, Wait );
break;
case AcquireSharedStarveExclusive:
Acquired = ExAcquireSharedStarveExclusive( Resource, Wait );
break;
default:
Acquired = FALSE;
ASSERT( FALSE );
}
//
// If not acquired and the user didn't specifiy IgnoreWait then
// raise CANT_WAIT.
//
if (!Acquired && !IgnoreWait) {
CdRaiseStatus( IrpContext, STATUS_CANT_WAIT );
}
return Acquired;
}
BOOLEAN
CdAcquireForCache (
IN PFCB Fcb,
IN BOOLEAN Wait
)
/*++
Routine Description:
The address of this routine is specified when creating a CacheMap for
a file. It is subsequently called by the Lazy Writer for synchronization.
Arguments:
Fcb - The pointer supplied as context to the cache initialization
routine.
Wait - TRUE if the caller is willing to block.
Return Value:
None
--*/
{
PAGED_CODE();
ASSERT(IoGetTopLevelIrp() == NULL);
IoSetTopLevelIrp((PIRP)FSRTL_CACHE_TOP_LEVEL_IRP);
return ExAcquireResourceSharedLite( Fcb->Resource, Wait );
}
VOID
CdReleaseFromCache (
IN PFCB Fcb
)
/*++
Routine Description:
The address of this routine is specified when creating a CacheMap for
a virtual file. It is subsequently called by the Lazy Writer to release
a resource acquired above.
Arguments:
Fcb - The pointer supplied as context to the cache initialization
routine.
Return Value:
None
--*/
{
PAGED_CODE();
ASSERT(IoGetTopLevelIrp() == (PIRP)FSRTL_CACHE_TOP_LEVEL_IRP);
IoSetTopLevelIrp( NULL );
ExReleaseResourceLite( Fcb->Resource );
}
BOOLEAN
CdNoopAcquire (
IN PVOID Fcb,
IN BOOLEAN Wait
)
/*++
Routine Description:
This routine does nothing.
Arguments:
Fcb - The Fcb/Vcb which was specified as a context parameter for this
routine.
Wait - TRUE if the caller is willing to block.
Return Value:
TRUE
--*/
{
PAGED_CODE();
return TRUE;
}
VOID
CdNoopRelease (
IN PVOID Fcb
)
/*++
Routine Description:
This routine does nothing.
Arguments:
Fcb - The Fcb/Vcb which was specified as a context parameter for this
routine.
Return Value:
None
--*/
{
PAGED_CODE();
}
VOID
CdAcquireForCreateSection (
IN PFILE_OBJECT FileObject
)
/*++
Routine Description:
This is the callback routine for MM to use to acquire the file exclusively.
Arguments:
FileObject - File object for a Cdfs stream.
Return Value:
None
--*/
{
PAGED_CODE();
//
// Get the Fcb resource exclusively.
//
ExAcquireResourceExclusiveLite( &((PFCB) FileObject->FsContext)->FcbNonpaged->FcbResource,
TRUE );
//
// Take the File resource shared. We need this later on when MM calls
// QueryStandardInfo to get the file size.
//
// If we don't use StarveExclusive, then we can get wedged behind an
// exclusive waiter who is waiting on someone else holding it shared in the
// read->initializecachemap path (which calls createsection) who is in turn
// waiting on us to finish the create section.
//
ExAcquireSharedStarveExclusive( ((PFCB) FileObject->FsContext)->Resource,
TRUE );
}
VOID
CdReleaseForCreateSection (
IN PFILE_OBJECT FileObject
)
/*++
Routine Description:
This is the callback routine for MM to use to release a file acquired with
the AcquireForCreateSection call above.
Arguments:
FileObject - File object for a Cdfs stream.
Return Value:
None
--*/
{
PAGED_CODE();
//
// Release the resources.
//
ExReleaseResourceLite( &((PFCB) FileObject->FsContext)->FcbNonpaged->FcbResource );
ExReleaseResourceLite( ((PFCB) FileObject->FsContext)->Resource);
}