Accessing the BK2CVS repository [LWN.net]

The BK2CVS repository (which contains a CVS copy of Linus's public BitKeeper repository) has been offline for a bit due to the backdoor insertion attempt. When it returns, it may come back without the "pserver" access mode which is normally used for anonymous CVS updates. Pserver is convenient, but it increases the security exposure of the CVS repository and it is not supported by the kernel.org mirror system. Given that a very small number of people have been using that access mode, there seems to be a consensus that it can just go away.

People do use the CVS repository, however. It just turns out that many of them have noted that it is faster to use rsync to update the entire repository from a kernel.org mirror than to update it through CVS. The rsync approach looks like the way to go in the future, but it does have one potential difficulty: if the repository is updated in the middle of an rsync, the person downloading the copy might get an inconsistent tree. Kernel hackers have to deal with enough race conditions as it is; they would prefer not to encounter them while trying to update their copy of the mainline kernel repository.

The solution that is likely to be implemented involves the creation of a couple of sequence files. One is fetched before doing the big repository rsync, and the other afterward. If the sequence numbers in the two files do not match, the rsync operation raced with an update of the repository and needs to be retried. This is, of course, an Internet implementation of the seqlock algorithm used within the kernel. Look for an update script to show up soon.