Hello everyone, I had some help reviewing Btrfs disk format this week and now have a list of some key disk format changes. So, my plan is to cut a new release out of the btrfs-unstable tree (also pushing the changes into the stable tree) and then start on these changes: * Explicit back pointers for every reference count. This is a key part of online fsck and will require adding a new item type to the extent allocation tree. * Generation number in all forward pointers, allowing verification of objects once we find them on disk. This includes node pointers in the btree and directory item pointers. * Objectid allocation tree to allow unique inode numbers across subvolumes. Crucial for NFS and a few other things. * Add a 32 bit device id to block pointers, which will get used for storage pools. * Align and optimize existing disk format structs. Most of these are actually pretty small, and I'll try to stabilize things quickly. If you have a suggestion on changing the disk format, please let me know. -chris