The main issue here was that the old orphan test relied on deleting the
block that contained the most recent update. In the new design this
doesn't really work since updates get appended to metadata-pairs
incrementally.
This is fixed by instead using the truncate command on the appropriate
block. We're now passing orphan tests.
Before, the lfs had multiple paths to determine config options:
- lfs_config struct passed during initialization
- lfs_bd_info struct passed during block device initialization
- compile time options
This allowed different developers to provide their own needs
to the filesystem, such as the block device capabilities and
the higher level user's own tweaks.
However, this comes with additional complexity and action required
when the configurations are incompatible.
For now, this has been reduced to all information (including block
device function pointers) being passed through the lfs_config struct.
We just defer more complicated handling of configuration options to
the top level user.
This simplifies configuration handling and gives the top level user
the responsibility to handle configuration, which they probably would
have wanted to do anyways.
No longer need to be stored on disk, can be simulated on
the chip side. As mentioned in other commits, the parent
entries had dozens of problems with atomic updates, as
well as making everything just a bit more complex than
is needed.
Removing the dependency to the parent pointer solves
many issues with non-atomic updates of children's
parent pointers with respect to any move operations.
However, this comes with an embarrassingly terrible
runtime as the only other option is to exhaustively
check every dir entry to find a child's parent.
Fortunately, deorphaning should be a relatively rare
operation.
