v9fs_create
fid = v9fs_create(v9ses, dir, dentry, (char *) extension, perm,
fid = v9fs_create(v9ses, dir, dentry, NULL, perm, P9_ORDWR);
fid = v9fs_create(v9ses, dir, dentry, NULL, perm, P9_OREAD);
fid = v9fs_create(v9ses, dir, dentry, NULL, perm, p9_omode);