SUNRPC: Add a helper rpcauth_lookup_generic_cred()

The NFSv4 protocol allows clients to negotiate security protocols on the
fly in the case where an administrator on the server changes the export
settings and/or in the case where we may have a filesystem migration event.

Instead of having the NFS client code cache credentials that are tied to a
particular AUTH method it is therefore preferable to have a generic credential
that can be converted into whatever AUTH is in use by the RPC client when
the read/write/sillyrename/... is put on the wire.

We do this by means of the new "generic" credential, which basically just
caches the minimal information that is needed to look up an RPCSEC_GSS,
AUTH_SYS, or AUTH_NULL credential.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

5 files changed, 7 insertions, 8 deletions

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 6cea7479c5b4..d583654a0b39 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1966,7 +1966,7 @@ force_lookup:
         if (!NFS_PROTO(inode)->access)
                 goto out_notsup;
 
-        cred = rpcauth_lookupcred(NFS_CLIENT(inode)->cl_auth, 0);
+        cred = rpc_lookup_cred();
         if (!IS_ERR(cred)) {
                 res = nfs_do_access(inode, cred, mask);
                 put_rpccred(cred);
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index c49f6d8b42d2..15f787355d27 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -613,7 +613,7 @@ int nfs_open(struct inode *inode, struct file *filp)
         struct nfs_open_context *ctx;
         struct rpc_cred *cred;
 
-        cred = rpcauth_lookupcred(NFS_CLIENT(inode)->cl_auth, 0);
+        cred = rpc_lookup_cred();
         if (IS_ERR(cred))
                 return PTR_ERR(cred);
         ctx = alloc_nfs_open_context(filp->f_path.mnt, filp->f_path.dentry, cred);
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index bbb0d58ee6ac..f38d0573be18 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -1408,7 +1408,7 @@ nfs4_atomic_open(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
                 BUG_ON(nd->intent.open.flags & O_CREAT);
         }
 
-        cred = rpcauth_lookupcred(NFS_CLIENT(dir)->cl_auth, 0);
+        cred = rpc_lookup_cred();
         if (IS_ERR(cred))
                 return (struct dentry *)cred;
         parent = dentry->d_parent;
@@ -1443,7 +1443,7 @@ nfs4_open_revalidate(struct inode *dir, struct dentry *dentry, int openflags, st
         struct rpc_cred *cred;
         struct nfs4_state *state;
 
-        cred = rpcauth_lookupcred(NFS_CLIENT(dir)->cl_auth, 0);
+        cred = rpc_lookup_cred();
         if (IS_ERR(cred))
                 return PTR_ERR(cred);
         state = nfs4_do_open(dir, &path, openflags, NULL, cred);
@@ -1660,7 +1660,7 @@ nfs4_proc_setattr(struct dentry *dentry, struct nfs_fattr *fattr,
 
         nfs_fattr_init(fattr);
         
-        cred = rpcauth_lookupcred(NFS_CLIENT(inode)->cl_auth, 0);
+        cred = rpc_lookup_cred();
         if (IS_ERR(cred))
                 return PTR_ERR(cred);
 
@@ -1896,7 +1896,7 @@ nfs4_proc_create(struct inode *dir, struct dentry *dentry, struct iattr *sattr,
         struct rpc_cred *cred;
         int status = 0;
 
-        cred = rpcauth_lookupcred(NFS_CLIENT(dir)->cl_auth, 0);
+        cred = rpc_lookup_cred();
         if (IS_ERR(cred)) {
                 status = PTR_ERR(cred);
                 goto out;
diff --git a/fs/nfs/unlink.c b/fs/nfs/unlink.c
index 757415363422..3adf8b266461 100644
--- a/fs/nfs/unlink.c
+++ b/fs/nfs/unlink.c
@@ -234,7 +234,7 @@ nfs_async_unlink(struct inode *dir, struct dentry *dentry)
         if (data == NULL)
                 goto out;
 
-        data->cred = rpcauth_lookupcred(NFS_CLIENT(dir)->cl_auth, 0);
+        data->cred = rpc_lookup_cred();
         if (IS_ERR(data->cred)) {
                 status = PTR_ERR(data->cred);
                 goto out_free;
diff --git a/net/sunrpc/auth.c b/net/sunrpc/auth.c
index d65dd7940102..0632cd0a1ad7 100644
--- a/net/sunrpc/auth.c
+++ b/net/sunrpc/auth.c
@@ -356,7 +356,6 @@ rpcauth_lookupcred(struct rpc_auth *auth, int flags)
         put_group_info(acred.group_info);
         return ret;
 }
-EXPORT_SYMBOL_GPL(rpcauth_lookupcred);
 
 void
 rpcauth_init_cred(struct rpc_cred *cred, const struct auth_cred *acred,