[LU-18461] Lustre join file re-implementation

• Type: Improvement
• Resolution: Unresolved
• Priority: Minor
• Severity: 3
• Assignee: Alexey Lyashkov
• Reporter: Alexey Lyashkov

Description

So much workloads want to merge a several files in the one. Long time ago - lustre had a 'JOIN file' feature addressed it but it removed.

Once PFL exist it might be used to implement file join by adding components to a file with non-zero offset, but original PFL implementation has a bug/feature - which required start object from zero offset.

This prevents file join to use existing objects, and also caused troubles with large files on the ldiskfs backend.

Let's implement both features.

Issue Links

• is related to: LU-17326 Implement FALLOC_FL_COLLAPSE_RANGE and FALLOC_FL_INSERT_RANGE