On Dec 3, 2010, at 12:11 PM, Stanislav Kinsbursky wrote:

quoted text
> Default value for mount server port is set to NFS_UNSPEC_PORT (-1) and will not
> be changed during parsing mount options for mound data version 6. This default
> value will be showed for mountport in /proc/mounts always since current default
> check is for zero value. This small mistake leads to big problem, because
> during umount.nfs execution from old user-space utils (at least nfs-utils
> 1.0.9) this value will be used as the server port to connect to. This request
> will be rejected (since port is 65535) and thus nfs mount point can't be
> unmounted.

Note: this is only possible if /etc/mtab is a link to /proc/mounts.  Not all systems have this configuration.

quoted text
> 
> Kernel version affected: 2.6.37-rc4
> 
> Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
> 
> ---
> fs/nfs/super.c |    3 ++-
> 1 files changed, 2 insertions(+), 1 deletions(-)
> 
> diff --git a/fs/nfs/super.c b/fs/nfs/super.c
> index 6d6e21d..fd4cac8 100644
> --- a/fs/nfs/super.c
> +++ b/fs/nfs/super.c
> @@ -681,7 +681,8 @@ static void nfs_show_mountd_options(struct seq_file *m, struct nfs_server *nfss,
> 
> 	if (nfss->mountd_version || showdefaults)
> 		seq_printf(m, ",mountvers=%u", nfss->mountd_version);
> -	if (nfss->mountd_port || showdefaults)
> +	if (nfss->mountd_port != (unsigned short)NFS_UNSPEC_PORT ||
> +			showdefaults)
> 		seq_printf(m, ",mountport=%u", nfss->mountd_port);
> 
> 	nfs_show_mountd_netid(m, nfss, showdefaults);
> 
> --
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-- 
Chuck Lever
chuck[dot]lever[at]oracle[dot]com




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