Hi folks, This is the set of per-ag conversions that I'm proposing for the 5.20 cycle. It is the initial subset of changes that were listed in the larger "upcoming perag changes for shrink" patchset here: https://lore.kernel.org/linux-xfs/20220611012659.3418072-1-david@xxxxxxxxxxxxx/ This series drives the perag down into the AGI, AGF and AGFL access routines and unifies the perag structure initialisation with the high level AG header read functions. This largely replaces the xfs_mount/agno pair that is passed to all these functions with a perag, and in most places we already have a perag ready to pass in. There are a few places where perags need to be grabbed before reading the AG header buffers - some of these will need to be driven to higher layers to ensure we can run operations on AGs without getting stuck part way through waiting on a perag reference. The latter section of this patchset moves some of the AG geometry information from the xfs_mount to the xfs_perag, and starts converting code that requires geometry validation to use a perag instead of a mount and having to extract the AGNO from the object location. This also allows us to store the AG size in the perag and then we can stop having to compare the agno against sb_agcount to determine if the AG is the last AG and so has a runt size. This greatly simplifies some of the type validity checking we do and substantially reduces the CPU overhead of type validity checking. It also cuts over 1.2kB out of the binary size. This runs through fstests cleanly - I don't expect there to be hidden surprises in it so I think these patches are good to go for the 5.20 cycle. Comments and thoughts welcome.... -Dave.
