Interrupt 21h Function 440Dh Minor Code 6Ah 

Unlocks the logical volume or decrements the lock level.

mov ax, 440Dh      ; generic IOCTL

mov bl, DriveNum   ; see below

mov ch, 08h        ; device category (must be 08h)

mov cl, 6Ah        ; Unlock Logical Volume

int 21h

jc error

Parameters

DriveNum

Drive to unlock. This parameter can be 0 for the default drive, 1 for A, 2 for B, and so on.

Return Value

Clears the carry flag if successful. Otherwise, the function sets the carry flag and sets the AX register to an error value.

Remarks

This function is used to release the lock obtained by using Lock Logical Volume (Interrupt 21h Function 440Dh Minor Code 4Ah306_4U). Only the lock owner can release the lock on a volume.

To release the lock on the volume, an application must call Unlock Logical Volume the same number of times that Lock Logical Volume was called.