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3f786596e0
This fixes a potential fence post failure like the following: error: 1 holders exceeded alloc budget av: bef 7407 now 7392, fr: bef 8185 now 7672 The code is only accounting for the freed btree blocks, not the dirtying of other items. So it's possible to be at exactly (COMMIT_HOLD_ALLOC_BUDGET / 2), dirty some log btree blocks, loop again, then consume another (COMMIT_HOLD_ALLOC_BUDGET / 2) and blow past the total budget. In this example, we went over by 13 blocks. By only consuming up to 1/8 of the budget on each loop, and committing when we have consumed 3/4 of the budget, we can avoid the fence post condition. 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
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