ext2fs_alloc
error = ext2fs_alloc(ip, bn,
error = ext2fs_alloc(ip, lbn, pref, cred, &newb);
error = ext2fs_alloc(ip, lbn, pref, cred, &newb);
error = ext2fs_alloc(ip, lbn, pref, cred, &newb);
int ext2fs_alloc(struct inode *, daddr_t, daddr_t , kauth_cred_t,