An f2fs teardown

I believe btrfs has improved significantly in this area, but its design means that it won't be as good as f2fs on the media that f2fs optimizes for. The issue with b-tree updates that Ted mentions in the link is something that f2fs avoids by having another level of indirection that is not copy-on-write, and btrfs suffers more from fragmentation because it intentionally does not garbage-collect.

On a lot of flash devices, btrfs starts out significantly faster than ext4 after a fresh mkfs, but it's possible that btrfs performance degrades more as the file system fragments with aging. I don't have any data to back that up though.