target/user: Disallow BIDI and COMPARE AND WRITE cmds for TCMU I/O mode

I/O mode is a partial-passthrough mode that saves userspace from handling
the complete set of required SCSI commands. Due to some issues with
emulation, it is preferable to not include BIDI commands like XDWRITEREAD,
and also COMPARE AND WRITE. If these are needed, the forthcoming
full-passthrough mode will allow their use.

Signed-off-by: Andy Grover <>
2 files changed