FltSetVolumeContext function

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NTSTATUS FLTAPI FltSetVolumeContext(
  PFLT_VOLUME               Volume,
  FLT_SET_CONTEXT_OPERATION Operation,
  PFLT_CONTEXT              NewContext,
  PFLT_CONTEXT              *OldContext
);

Parameters

Volume

Opaque volume pointer for the volume.

Operation

Flag specifying details of the operation to be performed. This parameter must be one of the following:

FLT_SET_CONTEXT_REPLACE_IF_EXISTS

If a context is already set, replace it with NewContext. Otherwise, insert NewContext into the list of contexts for the volume.

FLT_SET_CONTEXT_KEEP_IF_EXISTS

If a context is already set, return STATUS_FLT_CONTEXT_ALREADY_DEFINED. Otherwise, insert NewContext into the list of contexts for the volume.

NewContext

Pointer to the new context to be set for the volume. This parameter is required and cannot be NULL.

OldContext

Pointer to a caller-allocated variable that receives the address of the existing volume context for Instance. This parameter is optional and can be NULL. (For more information about this parameter, see the following Remarks section.)

Return value

FltSetVolumeContext returns STATUS_SUCCESS or an appropriate NTSTATUS value such as one of the following:

Remarks

A minifilter driver calls FltSetVolumeContext to attach a context to a volume, or to remove or replace an existing volume context. A minifilter driver can attach only one context to a volume.

A successful call to FltSetVolumeContext increments the reference count on NewContext. If FltSetVolumeContext fails, the reference count remains unchanged. In either case, the filter calling FltSetVolumeContext must call FltReleaseContext to decrement the NewContext object. If FltSetVolumeContext fails and if the OldContext parameter is not NULL and does not point to NULL_CONTEXT then OldContext is a referenced pointer to the context currently associated with the transaction. The filter calling FltSetVolumeContext must call FltReleaseContext for OldContext as well.

Note that the OldContext pointer returned by FltSetVolumeContext must also be released by calling FltReleaseContext when it is no longer needed. For more information, see Setting Contexts and Releasing Contexts.

To allocate a new context, call FltAllocateContext.

To get a volume context, call FltGetVolumeContext.

To delete a volume context, call FltDeleteVolumeContext or FltDeleteContext.

For more information about context reference counting, see Referencing Contexts.

Requirements