NtDoc

No description available.

Windows Driver Kit DDI reference (ni-ehstorioctl-ioctl_ehstor_device_set_queue_state)

IOCTL_EHSTOR_DEVICE_SET_QUEUE_STATE IOCTL

Description

The IOCTL_EHSTOR_DEVICE_SET_QUEUE_STATE request is sent by silo drivers and applications to change the state of a storage device queue. IO requests in the storage device queue are held when the device is temporarily unauthorized.

Parameters

Major code

Input buffer

The input buffer at Irp->AssociatedIrp.SystemBuffer contains an ACT_QUEUE_STATE structure. ACT_QUEUE_STATE is declared in ehstorioctl.h as the following.

typedef struct tagACT_QUEUE_STATE
{
    BOOLEAN fFrozen;
} ACT_QUEUE_STATE;

Input buffer length

The length of an ACT_QUEUE_STATE structure.

Output buffer

None.

Output buffer length

None.

Input/output buffer

Input/output buffer length

Status block

One of the following values can be returned in the Status field.

Status Value	Description
STATUS_SUCCESS	The queue state was changed successfully.
STATUS_INVALID_BUFFER_SIZE	The input buffer length is too small.
STATUS_ACCESS_DENIED	The IOCTL request was not issued by a silo driver.

-fFrozen

The freeze state of the IO request queue for a storage device. If set to TRUE, the queue is frozen and all IO requests sent to the storage device are held. Otherwise, IO requests in the device queue are processed.

Remarks

Silo drivers or applications can freeze the storage device IO request queue if temporary unauthorization is needed. Normally, temporary unauthorization occurs during low power states or when a policy requires locking of Enhanced Storage devices such as a locked user session. In such a case, it is preferable to put pending IO requests on hold rather than fail the IO requests and cause data loss.

To prevent abuse of the IOCTL_EHSTOR_DEVICE_SET_QUEUE_STATE request by applications, only a driver can issue this IOCTL. If sent from a user mode application, this request will fail with STATUS_ACCESS_DENIED.

IOCTL_EHSTOR_DEVICE_SET_QUEUE_STATE - NtDoc