Linux was using BitKeeper, a commercial DVCS. The raison d'etre for git was because the company behind BitKeeper revoked the license for the Linux guys to use it.
http://en.wikipedia.org/wiki/BitKeeper
They moved to a DVCS to solve some of the workflow issues, then Linus created git in large part because of the licensing issues.
Another detail missed in my previous post: If I remember rightly there were a couple of F/OSS DVCS's in development at the time, but he chose to write his own as some of them were not yet near stable and the others didn't quite work the way he wanted. I dimly recall some criticism for choosing a commercial product prior to git, and that decision was for much the same reasons git was created instead of using one of the other available options.
They moved to a DVCS to solve some of the workflow issues, then Linus created git in large part because of the licensing issues.
Another detail missed in my previous post: If I remember rightly there were a couple of F/OSS DVCS's in development at the time, but he chose to write his own as some of them were not yet near stable and the others didn't quite work the way he wanted. I dimly recall some criticism for choosing a commercial product prior to git, and that decision was for much the same reasons git was created instead of using one of the other available options.