repair: set the in-core inode parent in phase 3

repair: set the in-core inode parent in phase 3

The inode processing code checks and resets invalid parent values on
physical inodes in phase 3 but waits to update the parent value in
the in-core tracking until phase 4. There doesn't appear to be any
specific reason for the latter beyond caution. In reality, the only
reason this doesn't cause problems is that phase 3 replaces an
invalid on-disk parent with another invalid value, so the in-core
parent returned by phase 4 translates to NULLFSINO.

This is subtle and fragile. To eliminate this duplicate processing
behavior and break the subtle dependency of requiring an invalid
dummy value in physical directory inodes, update the in-core parent
tracking structure at the same point in phase 3 that physical inodes
are updated. Invalid on-disk parent values will still translate to
NULLFSINO for the in-core tracking to be identified by later phases.
This ensures that if a valid dummy value is placed in a physical
inode (such as rootino) with an invalid parent in phase 3, phase 4
won't mistakenly return the valid dummy value to be incorrectly set
in the in-core tracking over the NULLFSINO value that represents the
broken on-disk state.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>