fix multipart RDMA: propagate rdmaclient, per-part CRC64NVME, complete XML

[harshavardhana]

Summary

The multipart RDMA path (added in #214) silently never went over RDMA, and once a server-side CRC64NVME requirement was added it started failing with InvalidPart on Complete. Three latent bugs:

1. Client::PutObject's multipart loop never propagated rdmaclient to UploadPartArgs. BaseClient::UploadPart's RDMA branch (which keys on args.rdmaclient != nullptr) was unreachable for multipart — every part went over plain HTTP.
2. No per-part CRC64NVME was computed or sent. When the server (or bucket policy) requires CRC64NVME, the part request was rejected with (checksum missing, want "CRC64NVME", got "").
3. Part struct had no checksum field and CompleteMultipartUpload XML omitted <ChecksumCRC64NVME>. Even if parts uploaded successfully, the server's part-list validation failed with InvalidPart.

Changes

• utils.h / utils.cc: add Crc64Nvme(data, len) and Crc64NvmeBase64(data, len). Table-driven NVMe E2E CRC-64 (polynomial 0xad93d23594c93659, reflected, init/xor 0xffffffffffffffff), lazily initialised via local static. Verified against the NVMe spec test vector 123456789 → 0xae8b14860a799888.
• types.h: add Part::checksum_crc64nvme and a 3-arg constructor.
• baseclient.cc: emit <ChecksumCRC64NVME> in CompleteMultipartUpload XML when the per-part checksum is non-empty.
• client.cc: in PutObject's multipart loop — declare x-amz-checksum-algorithm: CRC64NVME on Create, propagate up_args.rdmaclient, compute per-part CRC64NVME on host buffers (cuObjClient::getMemoryType == CUOBJ_MEMORY_SYSTEM), set both up_args.checksum_crc64nvme (consumed by rdma.h) and up_args.headers[\"x-amz-checksum-crc64nvme\"] (consumed by the HTTP fallback in BaseClient::UploadPart), and propagate the checksum into the assembled Part list.

GPU buffers (CUDA_DEVICE / CUDA_MANAGED) cannot be hashed by the CPU; in that case we leave the checksum empty and the RDMA path will surface a 501 to the caller, or the caller supplies a pre-computed checksum via args.headers.

Verification

Tested against a live minio.rdma server (15.15.15.59:9200) across a Mellanox mlx5_0 fabric, using the existing PutObject example with a 20 MiB file forcing 2 parts (16 MiB + 4 MiB):

$ ./PutObject 15.15.15.59:9200 minioadmin minioadmin
my-object is successfully created etag=fe2f8e526e386a020064a32911319808-2

The -2 suffix on the final ETag confirms the multipart path ran, and the upload no longer falls back to HTTP.

Test plan

• Reviewer builds with -DMINIO_CPP_ENABLE_RDMA=ON — should compile clean.
• Reviewer builds with the default (no RDMA) — should be unaffected (Part 3-arg ctor is benign; Complete XML change only emits the element when checksum is non-empty).
• If reviewer has access to a cuObjServer-aware MinIO endpoint and an RDMA fabric, run any large-file PutObject (>16 MiB) and confirm it succeeds.

Companion PR

A matching native multipart-RDMA implementation in minio-rs is posted alongside this one (it ran into the same CRC64NVME and Complete-XML requirements during initial development; both SDKs now agree against the same server).

[Copilot]

Pull request overview

Fixes three latent bugs in the multipart RDMA upload path introduced in #214: (1) rdmaclient was not propagated to per-part UploadPartArgs, (2) no per-part CRC64NVME was computed or sent, and (3) the Part struct/CompleteMultipartUpload XML had no ChecksumCRC64NVME field, causing InvalidPart failures from servers that require the checksum.

Changes:

• Add utils::Crc64Nvme / utils::Crc64NvmeBase64 helpers (table-driven NVMe E2E CRC-64).
• Add Part::checksum_crc64nvme and emit <ChecksumCRC64NVME> in the Complete XML.
• In Client::PutObject's multipart loop, declare CRC64NVME on Create, propagate rdmaclient, compute per-part CRC on host buffers, and pass the checksum through to the assembled Part.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
include/miniocpp/utils.h	Declares the new CRC64NVME helpers.
src/utils.cc	Implements the reflected-poly CRC64NVME and its base64 wrapper.
include/miniocpp/types.h	Adds checksum_crc64nvme field and 3-arg constructor to Part.
src/baseclient.cc	Emits <ChecksumCRC64NVME> in CompleteMultipartUpload XML when present.
src/client.cc	Multipart loop now declares CRC64NVME, propagates rdmaclient, computes per-part CRC, and forwards it into the Part list.

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