NFS: Only reference user namespace from nfs4idmap struct instead of cred

The nfs4idmapper only needs access to the user namespace, and not the
entire cred struct. This replaces the struct cred* member with
struct user_namespace*. This is mostly hygiene, so we don't have to
hold onto the cred object, which has extraneous references to
things like user_struct. This also makes switching away
from init_user_ns more straightforward in the future.

Signed-off-by: Sargun Dhillon <sargun@sargun.me>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

diff --git a/fs/nfs/nfs4idmap.c b/fs/nfs/nfs4idmap.c
index 62e6eea5c516d8c1a19fd96ea4d749b439875da9..8d8aba305ecca02d8776c3439de736c951edee05 100644 (file)
--- a/fs/nfs/nfs4idmap.c
+++ b/fs/nfs/nfs4idmap.c
@@ -46,6 +46,7 @@
 #include <keys/user-type.h>
 #include <keys/request_key_auth-type.h>
 #include <linux/module.h>
+#include <linux/user_namespace.h>
 
 #include "internal.h"
 #include "netns.h"
@@ -69,13 +70,13 @@ struct idmap {
        struct rpc_pipe         *idmap_pipe;
        struct idmap_legacy_upcalldata *idmap_upcall_data;
        struct mutex            idmap_mutex;
-       const struct cred       *cred;
+       struct user_namespace   *user_ns;
 };
 
 static struct user_namespace *idmap_userns(const struct idmap *idmap)
 {
-       if (idmap && idmap->cred)
-               return idmap->cred->user_ns;
+       if (idmap && idmap->user_ns)
+               return idmap->user_ns;
        return &init_user_ns;
 }
 
@@ -286,7 +287,7 @@ static struct key *nfs_idmap_request_key(const char *name, size_t namelen,
        if (ret < 0)
                return ERR_PTR(ret);
 
-       if (!idmap->cred || idmap->cred->user_ns == &init_user_ns)
+       if (!idmap->user_ns || idmap->user_ns == &init_user_ns)
                rkey = request_key(&key_type_id_resolver, desc, "");
        if (IS_ERR(rkey)) {
                mutex_lock(&idmap->idmap_mutex);
@@ -462,7 +463,7 @@ nfs_idmap_new(struct nfs_client *clp)
                return -ENOMEM;
 
        mutex_init(&idmap->idmap_mutex);
-       idmap->cred = get_cred(clp->cl_rpcclient->cl_cred);
+       idmap->user_ns = get_user_ns(clp->cl_rpcclient->cl_cred->user_ns);
 
        rpc_init_pipe_dir_object(&idmap->idmap_pdo,
                        &nfs_idmap_pipe_dir_object_ops,
@@ -486,7 +487,7 @@ nfs_idmap_new(struct nfs_client *clp)
 err_destroy_pipe:
        rpc_destroy_pipe_data(idmap->idmap_pipe);
 err:
-       put_cred(idmap->cred);
+       get_user_ns(idmap->user_ns);
        kfree(idmap);
        return error;
 }
@@ -503,7 +504,7 @@ nfs_idmap_delete(struct nfs_client *clp)
                        &clp->cl_rpcclient->cl_pipedir_objects,
                        &idmap->idmap_pdo);
        rpc_destroy_pipe_data(idmap->idmap_pipe);
-       put_cred(idmap->cred);
+       put_user_ns(idmap->user_ns);
        kfree(idmap);
 }