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Auke Kok
ef9be95f5c
This function determines if the local inode is cached under a different mode in the client local state. On receiving an updated mode it should therefore inspect it's own lock mode and not the mode passed by the server, which can have a different view after recovery. This was caught twice in CI by `BUG_ON(atomic64_read(&si->last_refreshed) > refresh_gen) in scoutfs_inode_refresh` in scoutfs_inode_refresh() during the lock-recover-invalidate test - our most flakey CI test by a mile. Pulling the core revealed the lock was mode=WRITE but refresh_gen=0 with invalidate_pending=1, which means it should have had refresh_gen assigned on the null to write transition. This happens because it's only assigned if the server-supplied lock changes, because it doesn't look at the client's view of the state: `!can_read(nl->old_mode) && can_read(nl->new_mode)` Exactly the thing that can go wrong after a server fence/recovery, as exposed by this CI test. Signed-off-by: Auke Kok <auke.kok@versity.com>
Introduction
scoutfs is a clustered in-kernel Linux filesystem designed to support large archival systems. It features additional interfaces and metadata so that archive agents can perform their maintenance workflows without walking all the files in the namespace. Its cluster support lets deployments add nodes to satisfy archival tier bandwidth targets.
The design goal is to reach file populations in the trillions, with the archival bandwidth to match, while remaining operational and responsive.
Highlights of the design and implementation include:
- Fully consistent POSIX semantics between nodes
- Atomic transactions to maintain consistent persistent structures
- Integrated archival metadata replaces syncing to external databases
- Dynamic seperation of resources lets nodes write in parallel
- 64bit throughout; no limits on file or directory sizes or counts
- Open GPLv2 implementation
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