fix: Stat() returns Size 0 for RDMA GET objects - #2263

Problem

The RDMA GetObject fast path (api-get-object.go, gated on opts.RDMABuffer != nil && c.rdmaEnabled) builds the returned *Object with isClosed: true, objectInfoSet: true and objectInfo{Size: n} — the payload is delivered out-of-band over RDMA, so there is no streaming HTTP body to read.

Object.Stat() short-circuits on o.isClosed:

if o.prevErr != nil && o.prevErr != io.EOF || o.isClosed {
    return ObjectInfo{}, o.prevErr   // Size 0, nil
}
...
return o.objectInfo, nil             // never reached for RDMA

so Stat().Size is always 0 for an RDMA GET, even though the transfer moved the full object. Callers that validate the returned size (e.g. warp --rdma) see a spurious unexpected download size, got:0 on every RDMA GET.

Fix

Return the cached objectInfo when objectInfoSet is true, before the isClosed check. Error-closed objects are still caught first by the prevErr guard, so existing semantics are preserved.

Testing

Validated against an RDMA-capable MinIO AIStor endpoint with warp --rdma=cpu (256 MiB objects, coe cluster): unexpected download size errors went from 100% of RDMA GETs to 0 at concurrency 4 and 32; GET throughput 7.0 GiB/s (c4) / 36.2 GiB/s (c32), 0 PUT errors. go build ./..., go vet, gofmt clean.

Summary by CodeRabbit

• Bug Fixes
  • Fixed object status retrieval after closure.
  • Cached object information is now returned when available, including for RDMA GET operations.
  • Improved handling of closed objects without previously stored status information.