Re: [Qemu-devel] 9pfs troubles (was Re: [PATCH 1/4] hw/9pfs: fix error handing in local_ioc_getversion())

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

"Michael S. Tsirkin" <mst@redhat.com> writes:

> On Tue, Feb 04, 2014 at 12:51:25PM +0530, Aneesh Kumar K.V wrote:
>> "Michael S. Tsirkin" <mst@redhat.com> writes:
>> 
>> > On Mon, Feb 03, 2014 at 03:05:10PM +0530, Aneesh Kumar K.V wrote:
>> >> "Michael S. Tsirkin" <mst@redhat.com> writes:
>> >> 
>> >> > Haven't used 9pfs in a while.
>> >> > I thought these patches are a good time to play with it some more.
>> >> > I have encountered two issues.
>> >> >
>> >> > What I'm doing:
>> >> > host: qemu a75143eda2ddf581b51e96c000974bcdfe2cbd10.
>> >> >
>> >> > /scm/qemu/x86_64-softmmu/qemu-system-x86_64 -enable-kvm -m 1g -cpu kvm64
>> >> > -smp 2  f20-x64.qcow2  -netdev user,id=foo -redir tcp:8022::22 -device
>> >> > virtio-net,netdev=foo  -serial stdio -fsdev
>> >> > local,security_model=none,id=fsdev0,path=/lib/modules/ -device
>> >> > virtio-9p-pci,id=fs0,fsdev=fsdev0,mount_tag=libmodulesshare -fsdev
>> >> > local,security_model=none,id=fsdev1,path=/boot -device
>> >> > virtio-9p-pci,id=fs1,fsdev=fsdev0,mount_tag=bootshare -no-reboot
>> >> > -snapshot
>> >> >
>> >> > guest: Fedora 20
>> >> >
>> >> > added this in /etc/fstab:
>> >> >
>> >> > bootshare       /share/boot     9p      trans=virtio,version=9p2000.L 0 0
>> >> > libmodulesshare /share/lib/modules      9p trans=virtio,version=9p2000.L 0 0
>> >> >
>> >> >
>> >> > I have encountered two issues:
>> >> >
>> >> > 1. mount failure on boot
>> >> > If I try to mount on boot through fstab, I get:
>> >> > [    2.270157] 9pnet: Could not find request transport: virtio
>> >> > [    2.270158] 9pnet: Could not find request transport: virtio
>> >> 
>> >> 
>> >> Missing 9pnet_virtio.ko module ? 
>> >
>> > Maybe it's loaded too late. But when I get to plymouth prompt
>> > it's loaded fine.
>
> Any idea about this one? Do you have guests with 9pfs
> and virtio as modules and 9pfs mounted from /etc/fstab?

No, I generally have everything builtin for guest. 

>
>> >> >
>> >> > If I then re-try mount, it succeeds immediately!
>> >> >
>> >> > Some kind of dependency issue?
>> >> >
>> >> > 2. files immediately in the mounted directory aren't visible on the
>> >> > guest under /share/boot.
>> >> > For example, files under /boot on host are not visible
>> >> > on guest, files under child directories seem visible.
>> >> 
>> >> 
>> >> can you share more details on this ? /boot permissions. ls -al output on
>> >> host etc.
>> >> 
>> >> -aneesh
>> >
>> > for /boot:
>> > dr-xr-xr-x. 7 root root 12288 Feb  2 23:41 /boot/
>> >
>> > $ ls -la
>> > total 739740
>> > dr-xr-xr-x.  7 root root    12288 Feb  2 23:41 .
>> > dr-xr-xr-x. 22 root root     4096 Feb  2 19:16 ..
>> > -rw-r--r--.  1 root root   138741 Dec 23 19:19 config-3.12.6-200.fc19.i686
>> > -rw-r--r--.  1 root root   138724 Jan 10 18:06 config-3.12.7-200.fc19.i686
>> > -rw-r--r--.  1 root root   138724 Jan 16 06:43
>> > config-3.12.8-200.fc19.i686
>> 
>> 
>> Related to SELinux errors ? can you double check you don't selinux
>> errors.
>
> No, I didn't see any selinux errors.
> Also was able to stat and read files as a regular user.
>
>> Can you also share the file listing on the guest ?
>
> Interestingly, the problem seems to be partially gone.
> Not sure what did I change
> What I do still see now is this:
>
> Host:
> $ ls -l /boot/initramfs-3.11.0-rc5-mst.img
> -rw-------. 1 root root 7659204 Aug 18 13:21 /boot/initramfs-3.11.0-rc5-mst.img
> Guest:
> ls -l /share/initramfs-3.11.0-rc5-mst.img 
> ls: cannot access /share/initramfs-3.11.0-rc5-mst.img: Permission denied
>
>

So you are able to stat the file as the same user the qemu is running
?. That is strange. I am not able to reproduce the problem. You could
possibly instrument the virtio-9p-local.c and see the exact error ?

-aneesh