Re: [RFC PATCH 5 3/7] nfsd - use service thread if not executing in init namespace

[Ian Kent]

On Tue, 2015-03-31 at 09:14 -0400, J. Bruce Fields wrote:
> On Tue, Mar 31, 2015 at 11:14:58AM +0800, Ian Kent wrote:
> > From: Ian Kent <ikent@xxxxxxxxxx>
> > 
> > If nfsd is running within a container the client tracking operations
> > should run within their originating container also. To do that get a
> > token to a service thread created within the container environment
> > for usermode helper calls.
> > 
> > Signed-off-by: Ian Kent <ikent@xxxxxxxxxx>
> > Cc: Benjamin Coddington <bcodding@xxxxxxxxxx>
> > Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
> > Cc: J. Bruce Fields <bfields@xxxxxxxxxxxx>
> > Cc: David Howells <dhowells@xxxxxxxxxx>
> > Cc: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
> > Cc: Oleg Nesterov <onestero@xxxxxxxxxx>
> > Cc: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
> > Cc: Jeff Layton <jeff.layton@xxxxxxxxxxxxxxx>
> > ---
> >  fs/nfsd/netns.h       |    3 +++
> >  fs/nfsd/nfs4recover.c |   48 +++++++++++++++++++++++++++++++-----------------
> >  fs/nfsd/nfsctl.c      |    6 ++++++
> >  3 files changed, 40 insertions(+), 17 deletions(-)
> > 
> > diff --git a/fs/nfsd/netns.h b/fs/nfsd/netns.h
> > index ea6749a..099a3c5 100644
> > --- a/fs/nfsd/netns.h
> > +++ b/fs/nfsd/netns.h
> > @@ -112,6 +112,9 @@ struct nfsd_net {
> >  	u32 clientid_counter;
> >  
> >  	struct svc_serv *nfsd_serv;
> > +
> > +	/* Namespace token */
> > +	int umh_token;
> >  };
> >  
> >  /* Simple check to find out if a given net was properly initialized */
> > diff --git a/fs/nfsd/nfs4recover.c b/fs/nfsd/nfs4recover.c
> > index 1c307f0..2547edb 100644
> > --- a/fs/nfsd/nfs4recover.c
> > +++ b/fs/nfsd/nfs4recover.c
> > @@ -1184,7 +1184,8 @@ nfsd4_cltrack_grace_start(time_t grace_start)
> >  }
> >  
> >  static int
> > -nfsd4_umh_cltrack_upcall(char *cmd, char *arg, char *env0, char *env1)
> > +nfsd4_umh_cltrack_upcall(char *cmd, char *arg,
> > +			 char *env0, char *env1, int token)
> >  {
> >  	char *envp[3];
> >  	char *argv[4];
> > @@ -1209,7 +1210,11 @@ nfsd4_umh_cltrack_upcall(char *cmd, char *arg, char *env0, char *env1)
> >  	argv[2] = arg;
> >  	argv[3] = NULL;
> >  
> > -	ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_PROC);
> > +	if (token > 0)
> > +		ret = call_usermodehelper_service(argv[0], argv, envp,
> > +						  token, UMH_WAIT_PROC);
> > +	else
> > +		ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_PROC);
> 
> Do we really need to handle the init_net case specially, or could we
> just let it create a workqueue in that case as well?

That's pretty much up to you but there's still the need to get a token
to create the work queue (and put it to terminate it) or just pass 0 to
call_usermodehelper_service().

> 
> --b.
> 
> >  	/*
> >  	 * Disable the upcall mechanism if we're getting an ENOENT or EACCES
> >  	 * error. The admin can re-enable it on the fly by using sysfs
> > @@ -1252,14 +1257,8 @@ nfsd4_umh_cltrack_init(struct net *net)
> >  	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
> >  	char *grace_start = nfsd4_cltrack_grace_start(nn->boot_time);
> >  
> > -	/* XXX: The usermode helper s not working in container yet. */
> > -	if (net != &init_net) {
> > -		WARN(1, KERN_ERR "NFSD: attempt to initialize umh client "
> > -			"tracking in a container!\n");
> > -		return -EINVAL;
> > -	}
> > -
> > -	ret = nfsd4_umh_cltrack_upcall("init", NULL, grace_start, NULL);
> > +	ret = nfsd4_umh_cltrack_upcall("init", NULL,
> > +					grace_start, NULL, nn->umh_token);
> >  	kfree(grace_start);
> >  	return ret;
> >  }
> > @@ -1285,6 +1284,7 @@ nfsd4_umh_cltrack_create(struct nfs4_client *clp)
> >  {
> >  	char *hexid, *has_session, *grace_start;
> >  	struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);
> > +	int ret;
> >  
> >  	/*
> >  	 * With v4.0 clients, there's little difference in outcome between a
> > @@ -1312,7 +1312,10 @@ nfsd4_umh_cltrack_create(struct nfs4_client *clp)
> >  	grace_start = nfsd4_cltrack_grace_start(nn->boot_time);
> >  
> >  	nfsd4_cltrack_upcall_lock(clp);
> > -	if (!nfsd4_umh_cltrack_upcall("create", hexid, has_session, grace_start))
> > +	ret = nfsd4_umh_cltrack_upcall("create",
> > +				       hexid, has_session, grace_start,
> > +				       nn->umh_token);
> > +	if (!ret)
> >  		set_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags);
> >  	nfsd4_cltrack_upcall_unlock(clp);
> >  
> > @@ -1324,7 +1327,9 @@ nfsd4_umh_cltrack_create(struct nfs4_client *clp)
> >  static void
> >  nfsd4_umh_cltrack_remove(struct nfs4_client *clp)
> >  {
> > +	struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);
> >  	char *hexid;
> > +	int ret;
> >  
> >  	if (!test_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags))
> >  		return;
> > @@ -1336,9 +1341,13 @@ nfsd4_umh_cltrack_remove(struct nfs4_client *clp)
> >  	}
> >  
> >  	nfsd4_cltrack_upcall_lock(clp);
> > -	if (test_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags) &&
> > -	    nfsd4_umh_cltrack_upcall("remove", hexid, NULL, NULL) == 0)
> > -		clear_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags);
> > +	if (test_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags)) {
> > +		ret = nfsd4_umh_cltrack_upcall("remove",
> > +					       hexid, NULL, NULL,
> > +					       nn->umh_token);
> > +		if (ret == 0)
> > +			clear_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags);
> > +	}
> >  	nfsd4_cltrack_upcall_unlock(clp);
> >  
> >  	kfree(hexid);
> > @@ -1347,8 +1356,9 @@ nfsd4_umh_cltrack_remove(struct nfs4_client *clp)
> >  static int
> >  nfsd4_umh_cltrack_check(struct nfs4_client *clp)
> >  {
> > -	int ret;
> > +	struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);
> >  	char *hexid, *has_session, *legacy;
> > +	int ret;
> >  
> >  	if (test_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags))
> >  		return 0;
> > @@ -1366,7 +1376,9 @@ nfsd4_umh_cltrack_check(struct nfs4_client *clp)
> >  	if (test_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags)) {
> >  		ret = 0;
> >  	} else {
> > -		ret = nfsd4_umh_cltrack_upcall("check", hexid, has_session, legacy);
> > +		ret = nfsd4_umh_cltrack_upcall("check", hexid,
> > +					       has_session, legacy,
> > +					       nn->umh_token);
> >  		if (ret == 0)
> >  			set_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags);
> >  	}
> > @@ -1386,7 +1398,9 @@ nfsd4_umh_cltrack_grace_done(struct nfsd_net *nn)
> >  
> >  	sprintf(timestr, "%ld", nn->boot_time);
> >  	legacy = nfsd4_cltrack_legacy_topdir();
> > -	nfsd4_umh_cltrack_upcall("gracedone", timestr, legacy, NULL);
> > +	nfsd4_umh_cltrack_upcall("gracedone",
> > +				 timestr, legacy, NULL,
> > +				 nn->umh_token);
> >  	kfree(legacy);
> >  }
> >  
> > diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
> > index aa47d75..f5ae092 100644
> > --- a/fs/nfsd/nfsctl.c
> > +++ b/fs/nfsd/nfsctl.c
> > @@ -1224,6 +1224,8 @@ static __net_init int nfsd_init_net(struct net *net)
> >  		goto out_idmap_error;
> >  	nn->nfsd4_lease = 90;	/* default lease time */
> >  	nn->nfsd4_grace = 90;
> > +	if (net != &init_net)
> > +		nn->umh_token = umh_wq_get_token(nn->umh_token, "knfsd");
> >  	return 0;
> >  
> >  out_idmap_error:
> > @@ -1234,6 +1236,10 @@ out_export_error:
> >  
> >  static __net_exit void nfsd_exit_net(struct net *net)
> >  {
> > +	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
> > +
> > +	umh_wq_put_token(nn->umh_token);
> > +	nn->umh_token = 0;
> >  	nfsd_idmap_shutdown(net);
> >  	nfsd_export_shutdown(net);
> >  }


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