RxFsdDispatch function (mrx.h)

Article
10/11/2023

RxFsdDispatch implements the file system driver (FSD) dispatch for RDBSS to process an I/O request packet (IRP). A pointer to this routine is copied over the device driver dispatch table for the network mini-redirector driver by the RxDriverEntry routine when RDBSS is initialized.

Syntax

NTSTATUS RxFsdDispatch(
  [in] IN PRDBSS_DEVICE_OBJECT RxDeviceObject,
  [in] IN PIRP                 Irp
);

Parameters

[in] RxDeviceObject

A pointer to the RDBSS device object for this network mini-redirector.

[in] Irp

A pointer to the I/O request packet being processed.

Return value

RxFsdDispatch returns one of the following values:

Return code	Description
STATUS_INVALID_DEVICE_REQUEST	A request was made on an invalid device object. For example, this error is returned if a file system object is passed as the RxDeviceObject parameter. This status value indicates failure.
STATUS_OBJECT_NAME_INVALID	An invalid request was made to create a named pipe or a mailslot (the MajorFunction member of the Irp was IRP_MJ_CREATE_MAILSLOT or IRP_MJ_CREATE_NAMED_PIPE). This status value indicates failure.
STATUS_PENDING	An asynchronous request was made and the status of the request is pending.
STATUS_SUCCESS	The RxFsdDispatch routine call was successful.

Remarks

RxFsdDispatch is called by RDBSS to process an I/O request packet (IRP). These IRPs are normally received by RDBSS in response to a user-mode application requesting operations on a file. It is also possible for another kernel driver to issue such an IRP.

A pointer to RxFsdDispatch routine is copied over the driver dispatch table for a network mini-redirector driver when the RxDriverEntry routine is called to initialize RDBSS.

Internally, RDBSS maintains two dispatch vectors:

A common dispatch vector for most operations.
A private dispatch vector for file device FCB operations.

If the IRP is an IRP_MJ_CREATE request, then RxFsdDispatch will use a common dispatch vector. If the IRP is for an operation on an FCB of a file object, RxFsdDispatch will check if a private dispatch vector should be used. Otherwise a common dispatch vector will be used to process the IRP.

RxFsdDispatch calls internal routines to process the standard IRPs most of which result in a call to one of the callback routines implemented by the network mini-redirector driver.

A few IRPs are treated as special and handled internally by RDBSS. For example, the IRP_MJ_SYSTEM_CONTROL is used internally if WMI is enabled. IRP_MJ_CREATE_MAILSLOT or IRP_MJ_CREATE_NAMED_PIPE requests are treated specially and rejected (a STATUS_OBJECT_NAME_INVALID error is returned).

Requirements

Requirement	Value
Target Platform	Desktop
Header	mrx.h (include Mrx.h, Rxstruc.h, Struchdr.h)
IRQL	<= APC_LEVEL

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