Re: [Qemu-devel] 9p broken?

["Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>]

Avi Kivity <avi@redhat.com> writes:

> Having an annoying bug on i386 kvm I decided to debug it buy running an
> i386 guest on my x86_64 host, use 9p to access a guest image, and run it
> using nested kvm.
>
> However, 9p appears to be broken: first, the configure test fails (patch
> sent).  Second, while mount works, ls on the mount point causes qemu to
> crash with
>
> (gdb) bt
> #0  error_set (errp=0x7fffe95fb128, fmt=0x5555558d4568 "{ 'class':
> 'VirtFSFeatureBlocksMigration', 'data': { 'path': %s, 'tag': %s } }") at
> /home/tlv/akivity/qemu/error.c:32
> #1  0x000055555567cb06 in v9fs_attach (opaque=0x7fffe95e3020) at
> /home/tlv/akivity/qemu/hw/9pfs/virtio-9p.c:988
> #2  0x000055555561d19f in coroutine_trampoline (i0=1449767888, i1=21845)
> at /home/tlv/akivity/qemu/coroutine-ucontext.c:138
> #3  0x00007ffff5a93ef0 in ?? ()	from /lib64/libc.so.6
> #4  0x00007fffffffce00 in ?? ()
> #5  0x0000000000000000 in ?? (
>
> **errp already points to a VirtFSFeatureBlocksMigration error;
> v9fs_attach() has been called a second time (the first time,
> understandably, on mount; the second on ls).
>

Ok we mount with fid uid = (unsigned)~0. So we need to attach again when
we do ls as root. I guess we can do that migration block in attach, or
we have to do it conditionally. We also can hit the same if we do a
path lookup as a different user.

-aneesh