FltProcessFileLock function (fltkernel.h)

Article
03/23/2023

The FltProcessFileLock routine processes and completes a file lock operation.

Syntax

FLT_PREOP_CALLBACK_STATUS FLTAPI FltProcessFileLock(
  [in]           PFILE_LOCK         FileLock,
  [in]           PFLT_CALLBACK_DATA CallbackData,
  [in, optional] PVOID              Context
);

Parameters

[in] FileLock

Pointer to the FILE_LOCK structure for the file. This structure must have been initialized by a previous call to FltAllocateFileLock or FltInitializeFileLock.

[in] CallbackData

Pointer to the callback data (FLT_CALLBACK_DATA) structure for the IRP_MJ_LOCK_CONTROL operation.

[in, optional] Context

Context pointer to be used when completing the operation. This context pointer is passed to the CompleteLockCallbackDataRoutine and UnlockRoutine callback routines that the minifilter driver registered in a previous call to FltAllocateFileLock. This parameter is optional and can be NULL.

Return value

FltProcessFileLock returns one of the following.

Return code	Description
FLT_PREOP_COMPLETE	The Filter Manager is done with the CallbackData, which can now be completed.
FLT_PREOP_DISALLOW_FASTIO	The CallbackData represents a fast I/O operation, and a minifilter driver in the stack has disallowed the fast I/O to be used for this operation. The Filter Manager does not send the operation to any minifilter drivers below the one that disallowed the operation. In this case, the Filter Manager only calls the postoperation callback routines (and CompleteLockCallbackDataRoutine callbacks) of the minifilter drivers above the minifilter driver that disallowed the fast I/O operation.
FLT_PREOP_PENDING	The lock operation has been pended.

Remarks

FltProcessFileLock processes a file lock (IRP_MJ_LOCK_CONTROL) operation. The lock operation can be a fast I/O or IRP-based operation.

For unlock operations, the Filter Manager calls the UnlockRoutine callback routine that the caller registered for the FILE_LOCK structure in a previous call to FltAllocateFileLock.

When the lock operation is completed, the Filter Manager calls the CompleteLockCallbackDataRoutine (PFLT_COMPLETE_LOCK_CALLBACK_DATA_ROUTINE) completion callback routine that the caller registered for the FILE_LOCK structure in a previous call to FltAllocateFileLock.

When the CallbackData parameter passed to FltProcessFileLock represents a fast I/O operation, the callback specified in CompleteLockCallbackDataRoutine parameter of the FltAllocateFileLock routine is not invoked. Only when the I/O operation in CallbackData is an IRP, and CompleteLockCallbackDataRoutine is not NULL, will the callback routine be called.

To determine whether the CallbackData represents a fast I/O operation, use the FLT_IS_FASTIO_OPERATION macro.

To allocate and initialize a new file lock structure, call FltAllocateFileLock.

To free an initialized FILE_LOCK structure, call FltFreeFileLock.

Requirements

Requirement	Value
Minimum supported client	Windows XP with SP2
Minimum supported server	Windows Server 2003 with SP1
Target Platform	Universal
Header	fltkernel.h (include Fltkernel.h)
Library	FltMgr.lib
DLL	Fltmgr.sys
IRQL	<= APC_LEVEL