Is a Berkeley license included in Linux? This is a broader issue than just this piece of code, it applies to anything from Linux that was borrowed from BSD.
Yes, it is. Those parts of Linux that were taken from BSD are supposed to include a notice acknowledging the source (it's a condition of the license).
The BSD license is less restrictive than the GPL: it doesn't require redistribution in source form. That's why you will find it in many operating systems, including Windows. The TCP/IP networking code is a common example.
$ uname -r
2.4.20-gentoo-r6
$ find . -name \*.[ch] | xargs egrep -il \ > 'Copyright \(c\) [0-9]+(, *[0-9]+)* (The )?Regents of the University of California'
./drivers/net/bsd_comp.c
./drivers/net/slhc.c
./drivers/char/tpqic02.c
./drivers/isdn/isdn_bsdcomp.c
./include/net/slhc_vj.h
./include/linux/quota.h