NFS: Fix error reporting in nfs_xdev_mount

Currently, nfs_xdev_mount converts all errors from clone_server() to
ENOMEM, which can then leak to userspace (for instance to 'mount'). Fix that.
Also ensure that if nfs_fs_mount_common() returns an error, we
don't dprintk(0)...

The regression originated in commit 3d176e3fe4f6dc379b252bf43e2e146a8f7caf01
(NFS: Use nfs_fs_mount_common() for xdev mounts)

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: stable@vger.kernel.org [>= 3.5]

1 files changed, 9 insertions, 13 deletions

diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index 2e7e8c878e5d..b056b1628722 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -2589,27 +2589,23 @@ nfs_xdev_mount(struct file_system_type *fs_type, int flags,
         struct nfs_server *server;
         struct dentry *mntroot = ERR_PTR(-ENOMEM);
         struct nfs_subversion *nfs_mod = NFS_SB(data->sb)->nfs_client->cl_nfs_mod;
-        int error;
 
-        dprintk("--> nfs_xdev_mount_common()\n");
+        dprintk("--> nfs_xdev_mount()\n");
 
         mount_info.mntfh = mount_info.cloned->fh;
 
         /* create a new volume representation */
         server = nfs_mod->rpc_ops->clone_server(NFS_SB(data->sb), data->fh, data->fattr, data->authflavor);
-        if (IS_ERR(server)) {
-                error = PTR_ERR(server);
-                goto out_err;
-        }
 
-        mntroot = nfs_fs_mount_common(server, flags, dev_name, &mount_info, nfs_mod);
-        dprintk("<-- nfs_xdev_mount_common() = 0\n");
-out:
-        return mntroot;
+        if (IS_ERR(server))
+                mntroot = ERR_CAST(server);
+        else
+                mntroot = nfs_fs_mount_common(server, flags,
+                                dev_name, &mount_info, nfs_mod);
 
-out_err:
-        dprintk("<-- nfs_xdev_mount_common() = %d [error]\n", error);
-        goto out;
+        dprintk("<-- nfs_xdev_mount() = %ld\n",
+                        IS_ERR(mntroot) ? PTR_ERR(mntroot) : 0L);
+        return mntroot;
 }
 
 #if IS_ENABLED(CONFIG_NFS_V4)