This just means a rewrite of the superblock entry with the new minor
version.
Though it's interesting to note, we don't need to rewrite the superblock
entry until the first write operation in the filesystem, an optimization
that is already in use for the fixing of orphans and in-flight moves.
To keep track of any outdated minor version found during lfs_mount, we
can carve out a bit from the reserved bits in our gstate. These are
currently used for a counter tracking the number of orphans in the
filesystem, but this is usually a very small number so this hopefully
won't be an issue.
In-device gstate tag:
[-- 32 --]
[1|- 11 -| 10 |1| 9 ]
^----^-----^--^--^-- 1-bit has orphans
'-----|--|--|-- 11-bit move type
'--|--|-- 10-bit move id
'--|-- 1-bit needs superblock
'-- 9-bit orphan count
Christopher Haster
4c9360020e