Re: [Nbd] nbd-client: bug in passing flags?

[Alex Bligh <alex@...872...>]

--On 16 May 2011 17:29:37 +0100 Alex Bligh <alex@...872...> wrote:

> I think the "<< 16" on line 215 is superfluous. The flags should
> simply be converted to host order, and assigned to "flags", so
> they will live in least significant two bytes (where they came
> from).

In fact, unless lack of caffeine is getting to me, I don't see
how these ever get passed to the kernel anyway. The read only
flag, if it is set right, causes the BLKROSET ioctl to be
executed.

However, there is also a member of struct nbd_device in the
kernel called flags. As far as I can tell, this is always zero,
as it is never set to anything else. However, it is tested
for NBD_READ_ONLY at line 460 of nbd.c in the kernel. Unless
I'm missing something (quite possible) I don't think this
check is ever activated. I need to pass the remainder of
the flags anyway, so I proposed adding a NBD_SET_FLAGS
ioctl to pass them through, and not checking for errors
in the client (as older kernels won't support it).

--
Alex Bligh