cifs: fix dfs-links

This fixes a regression following dfs links that was introduced in the
patch series for the new mount api.

Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/cifs/connect.c

@@ -2983,6 +2983,14 @@ expand_dfs_referral(const unsigned int xid, struct cifs_ses *ses,
 			rc = PTR_ERR(mdata);
 			mdata = NULL;
 		} else {
+			/*
+			 * We can not clear out the whole structure since we
+			 * no longer have an explicit function to parse
+			 * a mount-string. Instead we need to clear out the
+			 * individual fields that are no longer valid.
+			 */
+			kfree(ctx->prepath);
+			ctx->prepath = NULL;
 			rc = cifs_setup_volume_info(ctx, mdata, fake_devname);
 		}
 		kfree(fake_devname);