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f2a11d7777
The previous work we did introduce the per-lock spinlock and the refcount now make it easy to switch from an rbtree protected by a spinlock to a hash table protected by RCU read critical sections. The cluster lock lookup fast path now only dirties fields in the scoutfs_lock struct itself. We have to be a little careful when inserting so that users can't get references to locks that made it into the hash table but which then had to be removed because they were found to overlap. Freeing is straight forward and we only have to make sure to free the locks in RCU grace periods so that read sections can continue to reference the memory and see the refcount that indicates that the locks are freeing. A few remaining places were using the lookup rbtree to walk all locks, they're converted to using the range tree that we're keeping around to resolve overlapping ranges but which is also handy for iteration that isn't performance sensitive. The LRU still does create contention on the linfo spinlock on every lookup, fixing that is next. Signed-off-by: Zach Brown <zab@versity.com> Signed-off-by: Chris Kirby <ckirby@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
Community Mailing List
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