[RFC PATCH 7/8] nfs - cache_lib use namespace if not executing in init namespace

[Ian Kent <ikent@redhat.com>]

If the caller is running within a container then execute the usermode
helper callback within the init namespace of the container.

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/nfs/cache_lib.c    |    6 +++++-
 fs/nfsd/nfs4recover.c |    2 +-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/nfs/cache_lib.c b/fs/nfs/cache_lib.c
index 5f7b053..1f7f6c1 100644
--- a/fs/nfs/cache_lib.c
+++ b/fs/nfs/cache_lib.c
@@ -44,11 +44,15 @@ int nfs_cache_upcall(struct cache_detail *cd, char *entry_name)
 		entry_name,
 		NULL
 	};
+	int umh_flags = UMH_WAIT_EXEC;
 	int ret = -EACCES;
 
+	if (cd->net != &init_net)
+		umh_flags |= UMH_USE_NS;
+
 	if (nfs_cache_getent_prog[0] == '\0')
 		goto out;
-	ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
+	ret = call_usermodehelper(argv[0], argv, envp, umh_flags);
 	/*
 	 * Disable the upcall mechanism if we're getting an ENOENT or
 	 * EACCES error. The admin can re-enable it on the fly by using
diff --git a/fs/nfsd/nfs4recover.c b/fs/nfsd/nfs4recover.c
index b962856..0896ca7 100644
--- a/fs/nfsd/nfs4recover.c
+++ b/fs/nfsd/nfs4recover.c
@@ -1380,7 +1380,7 @@ nfsd4_umh_cltrack_check(struct nfs4_client *clp)
 	} else {
 		ret = nfsd4_umh_cltrack_upcall("check", hexid,
 					       has_session, legacy,
-					       mm->umh_flags);
+					       nn->umh_flags);
 		if (ret == 0)
 			set_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags);
 	}