Re: [Qemu-devel] 9pfs: unWRITAble dirs with random errors in guest

[Michael Tokarev <mjt@tls.msk.ru>]

Rehashing an old thread again...

28.02.2013 21:25, M. Mohan Kumar wrote:
> Michael Tokarev <mjt@tls.msk.ru> writes:
> 
> 
>> 28.02.2013 17:55, M. Mohan Kumar wrote:
>>> Michael Tokarev <mjt@tls.msk.ru> writes:
>>>
>>> Hi,
>>>
>>> Please try mounting with -oversion=9p2000.L
>>>
>>> With qemu-1.4.0 and 9p2000.L, I could not recreate this issue. ie not
>>> getting Unknown error during directory listing.
>>
>> Yes, with 9p2000.L it works fine, both reported
>> issues are gone.
>>
>>> I am using Guest kernel 3.8.0-rc5+.
>>
>> But do you see my original error, with the default mount version?
>> (I'm using 3.2 guest kernel if that matters, and it is also 32bits,
>> which should not matter).
> Yes, with default mount option, i am getting same error.

So, is there any intention to fix that for the default mount
options?  Or should the corresponding protocol be just marked
as broken and qemu to refuse its usage?  I think it is either
one or another, -- either fix or drop, that is, keeping
known-broken behavor isn't exactly the right thing.

Thanks,

/mjt

>>>> When I mount a 9pfs filesystem in guest with no write permission for
>>>> some dirs, I'm getting strange errors in guest.
>>>>
>>>> Host (as a regular user):
>>>>  qemu-system-x86_64 -virtfs local,path=/,security_model=mapped-file,mount_tag=tag
>>>>
>>>> Guest:
>>>>  # mount -t 9p -o trans=virtio,ro tag /mnt
>>>>  # ls /mnt
>>>>  ls: reading directory /mnt: Unknown error 593
>>>>  # ls /mnt/dev
>>>>  ls: reading directory /mnt/dev: Unknown error 849
>>>>  # ls /mnt/tmp
>>>>  [works]
>>>>  # ls /mnt/root
>>>>  ls: cannot open directory /mnt/root: Permission denied
>>>>
>>>> So, it reports errors while trying to _read_ (not open)
>>>> readable but non-writable dirs, and these errors are _random_.
>>>> It correctly reports errors when trying to open an unreadable
>>>> dir.
>>>>
>>>> This is 1.4.0.  Similar problem exists with earlier versions
>>>> of qemu.
>>>>
>>>> Thanks!
>>>>
>>>> /mjt
>>>
> 
>