BPIO_OPERATIONS enumeration (ntddstor.h)

BPIO_OPERATIONS defines the various BypassIO operations supported by the IOCTL_STORAGE_MANAGE_BYPASS_IO control code.

Syntax

typedef enum _BPIO_OPERATIONS {
  BPIO_OP_ENABLE,
  BPIO_OP_DISABLE,
  BPIO_OP_QUERY
} BPIO_OPERATIONS;

Constants

BPIO_OP_ENABLE Requests that BypassIO be enabled for the given volume or disk (device), which means that a driver might not see all reads/writes for that stack. NOTE All drivers in the volume and storage stacks have the opportunity to veto the BypassIO enable request, but are encouraged to keep it enabled as much as possible. On the pre-operation: * If a driver can support BypassIO for the given device, it should forward the request down the stack. * If a driver cannot support BypassIO for the given device, it should: * Update the BPIO_OUTPUT structure, including the operation NTSTATUS describing why the enable request was vetoed, the driver's name, and a unique, descriptive string with additional details about why it vetoed the enable request. * Complete IOCTL_STORAGE_MANAGE_BYPASS_IO with STATUS_SUCCESS. During the post-operation, the driver can see if all drivers below it are capable of supporting BypassIO. If yes, the driver should preserve any needed state for the file and continue completion processing. It is the driver's responsibility to maintain state to properly handle requests that might not be compatible with the BypassIO-enabled state. The file system maintains a per-volume count of how many files have BypassIO currently enabled. The BPIO_OP_ENABLE operation is sent only when this count transitions from zero to one. Even if a volume or storage stack driver vetoes BypassIO, the file system stack can continue to do BypassIO. This is because if someone has vetoed BypassIO on the volume stack, the file system can still bypass filters.
BPIO_OP_DISABLE Requests that BypassIO be disabled for the given volume/disk. It allows a driver to cleanup any associated BypassIO state. The file system sends this operation when the last BypassIO-enabled file is disabled or closed (its per-volume count transitions from one to zero). If a driver receives BPIO_OP_DISABLE but does not currently have BypassIO enabled, it should ignore the request. This operation should not be failed.
BPIO_OP_QUERY Queries whether BypassIO can be enabled for the given volume or disk. A storage driver should process this request similar to a BPIO_OP_ENABLE operation, filling in the same diagnostic information in the appropriate fields in the BPIO_OUTPUT structure. The major difference is that the driver does not enter the BypassIO ENABLE state during a QUERY.

Remarks

See BypassIO for storage drivers for more information.

Requirements

Requirement	Value
Minimum supported client	Windows 11
Header	ntddstor.h

See also

IOCTL_STORAGE_MANAGE_BYPASS_IO