[PATCH] dm: prevent possible buffer overflow in ioctl interface

[PATCH] dm: prevent possible buffer overflow in ioctl interface

Use the correct size for "name" in register_with_devfs().

During Al Viro's devfs cleanup a few versions ago, this function was
rewritten, and the "name" string added. The 32-byte size is not large
enough to prevent a possible buffer overflow in the sprintf() call,
since the hash cell can have a name up to 128 characters.