Improving ext4: bigalloc, inline data, and metadata checksums

I'm not sure that is an accurate portrayal of what happened, on this planet at least. My recollection from the time is that there were fundamental technical problems with the devfs implementation which is why it was redone into udev. I think those problems were some inherent race conditions on device add/removal, plus concerns about how much policy about /dev file names, permissions, etc was hard coded into the kernel and unmodifyable by an end user or sysadmin. That is just my recollection.