Bcachefs is a modern, general purpose, copy on write filesystem descended from bcache, a block layer cache.

The internal architecture is very different from most existing filesystems where the inode is central and many data structures hang off of the inode. Instead, bcachefs is architected more like a filesystem on top of a relational database, with tables for the different filesystem data types - extents, inodes, dirents, xattrs, et cetera.

bcachefs supports almost all of the same features as other modern COW filesystems, such as ZFS and btrfs, but in general with a cleaner, simpler, higher performance design.