Re: [Qemu-trivial] [PATCH] hw/9pfs: Fix errno value for xattr functions

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

01.10.2013 15:28, Daniel P. Berrange пишет:
> From: "Daniel P. Berrange" <berrange@redhat.com>
>
> If there is no operation driver for the xattr type the
> functions return '-1' and set errno to '-EOPNOTSUPP'.
> When the calling code sets 'ret = -errno' this turns
> into a large positive number.
>
> In Linux 3.11, the kernel has switched to using 9p
> version 9p2000.L, instead of 9p2000.u, which enables
> support for xattr operations. This on its own is harmless,
> but for another change which makes it request the xattr
> with a name 'security.capability'.
>
> The result is that the guest sees a succesful return
> of 95 bytes of data, instead of a failure with errno
> set to 95. Since the kernel expects a maximum of 20
> bytes for an xattr return this gets translated to the
> unexpected errno ERANGE.
>
> This all means that when running a binary off a 9p fs
> in 3.11 kernels you get a fun result of:
>
>    # ./date
>    sh: ./date: Numerical result out of range
>
> The only workaround is to pass 'version=9p2000.u' when
> mounting the 9p fs in the guest, to disable all use of
> xattrs.

Thanks, applied to the trivial patches queue.

/mjt