From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48500) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VR2jX-0001Ar-OC for qemu-devel@nongnu.org; Tue, 01 Oct 2013 12:23:44 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VR2jO-0007XM-Pk for qemu-devel@nongnu.org; Tue, 01 Oct 2013 12:23:35 -0400 Received: from e28smtp08.in.ibm.com ([122.248.162.8]:36917) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VR2jO-0007Wn-7c for qemu-devel@nongnu.org; Tue, 01 Oct 2013 12:23:26 -0400 Received: from /spool/local by e28smtp08.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 1 Oct 2013 21:53:24 +0530 From: "Aneesh Kumar K.V" In-Reply-To: <1380626897-500-1-git-send-email-berrange@redhat.com> References: <1380626897-500-1-git-send-email-berrange@redhat.com> Date: Tue, 01 Oct 2013 21:53:20 +0530 Message-ID: <87li2dc64n.fsf@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [Qemu-devel] [PATCH] hw/9pfs: Fix errno value for xattr functions List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Daniel P. Berrange" , qemu-devel@nongnu.org Cc: qemu-trivial@nongnu.org, Anthony Liguori "Daniel P. Berrange" writes: > From: "Daniel P. Berrange" > > 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. > > Signed-off-by: Daniel P. Berrange Reviewed-by: Aneesh Kumar K.V > --- > hw/9pfs/virtio-9p-xattr.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/hw/9pfs/virtio-9p-xattr.c b/hw/9pfs/virtio-9p-xattr.c > index 90ae565..3fae557 100644 > --- a/hw/9pfs/virtio-9p-xattr.c > +++ b/hw/9pfs/virtio-9p-xattr.c > @@ -36,7 +36,7 @@ ssize_t v9fs_get_xattr(FsContext *ctx, const char *path, > if (xops) { > return xops->getxattr(ctx, path, name, value, size); > } > - errno = -EOPNOTSUPP; > + errno = EOPNOTSUPP; > return -1; > } > > @@ -123,7 +123,7 @@ int v9fs_set_xattr(FsContext *ctx, const char *path, const char *name, > if (xops) { > return xops->setxattr(ctx, path, name, value, size, flags); > } > - errno = -EOPNOTSUPP; > + errno = EOPNOTSUPP; > return -1; > > } > @@ -135,7 +135,7 @@ int v9fs_remove_xattr(FsContext *ctx, > if (xops) { > return xops->removexattr(ctx, path, name); > } > - errno = -EOPNOTSUPP; > + errno = EOPNOTSUPP; > return -1; > > } > -- > 1.8.3.1