Re: [PATCH] nfsd: set the server_scope during service startup

["J. Bruce Fields" <bfields@fieldses.org>]

On Wed, Feb 19, 2020 at 03:52:15PM -0500, Scott Mayhew wrote:
> Currently, nfsd4_encode_exchange_id() encodes the utsname nodename
> string in the server_scope field.  In a multi-host container
> environemnt, if an nfsd container is restarted on a different host than
> it was originally running on, clients will see a server_scope mismatch
> and will not attempt to reclaim opens.
> 
> Instead, set the server_scope while we're in a process context during
> service startup, so we get the utsname nodename of the current process
> and store that in nfsd_net.

Thanks!  Just one nit:

> Signed-off-by: Scott Mayhew <smayhew@redhat.com>
> ---
>  fs/nfsd/netns.h   | 1 +
>  fs/nfsd/nfs4xdr.c | 3 ++-
>  fs/nfsd/nfssvc.c  | 3 +++
>  3 files changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/nfsd/netns.h b/fs/nfsd/netns.h
> index 2baf32311e00..c6d95700105e 100644
> --- a/fs/nfsd/netns.h
> +++ b/fs/nfsd/netns.h
> @@ -172,6 +172,7 @@ struct nfsd_net {
>  	unsigned int             longest_chain_cachesize;
>  
>  	struct shrinker		nfsd_reply_cache_shrinker;
> +	char			server_scope[UNX_MAXNODENAME+1];
>  };
>  
>  /* Simple check to find out if a given net was properly initialized */
> diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
> index 9761512674a0..209174ee431a 100644
> --- a/fs/nfsd/nfs4xdr.c
> +++ b/fs/nfsd/nfs4xdr.c
> @@ -4005,10 +4005,11 @@ nfsd4_encode_exchange_id(struct nfsd4_compoundres *resp, __be32 nfserr,
>  	int major_id_sz;
>  	int server_scope_sz;
>  	uint64_t minor_id = 0;
> +	struct nfsd_net *nn = net_generic(SVC_NET(resp->rqstp), nfsd_net_id);
>  
>  	major_id = utsname()->nodename;
>  	major_id_sz = strlen(major_id);

We should do this one too.  I'll fix that up and apply if that's OK.

--b.

> -	server_scope = utsname()->nodename;
> +	server_scope = nn->server_scope;
>  	server_scope_sz = strlen(server_scope);
>  
>  	p = xdr_reserve_space(xdr,
> diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
> index 3b77b904212d..c4e00979aca4 100644
> --- a/fs/nfsd/nfssvc.c
> +++ b/fs/nfsd/nfssvc.c
> @@ -749,6 +749,9 @@ nfsd_svc(int nrservs, struct net *net, const struct cred *cred)
>  	if (nrservs == 0 && nn->nfsd_serv == NULL)
>  		goto out;
>  
> +	strlcpy(nn->server_scope, utsname()->nodename,
> +		sizeof(nn->server_scope));
> +
>  	error = nfsd_create_serv(net);
>  	if (error)
>  		goto out;
> -- 
> 2.24.1