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

[Ian Kent <raven@themaw.net>]

From: Ian Kent <ikent@redhat.com>

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@redhat.com>
Cc: Benjamin Coddington <bcodding@redhat.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: J. Bruce Fields <bfields@fieldses.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Trond Myklebust <trond.myklebust@primarydata.com>
Cc: Oleg Nesterov <onestero@redhat.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Jeff Layton <jeff.layton@primarydata.com>
---
 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);
 	/*
 	 * 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);
 }