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Zach Brown
7720222588
The server's statfs request handler was intending to lock dirty structures as they were walked to get sums used for statfs fields. Other callers walk stable structures, though, so the summation calls had grown iteration over other structures that the server didn't know it had to lock. This meant that the server was walking unlocked dirty structures as they were being modified. The races are very tight, but it can result in request handling errors that shut down connections and IO errors from trying to read inconsistent refs as they were modified by the locked writer. We've built up infrastructure so the server can now walk stable structures just like the other callers. It will no longer wander into dirty blocks so it doesn't need to lock them and it will retry if its walk of stale data crosses a broken reference. Signed-off-by: Zach Brown <zab@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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