only do a multipart s3 copy when above the regular copy limit

[icewind1991]

Multipart copy seems problematic with some backends so avoid it when possible.

[icewind1991]

/backport to stable28

[icewind1991]

/backport to stable27

[solracsf]

Why don't test if MultiPart is supported? Something like:

if ($this->getObjectStore() instanceof IObjectStoreMultiPartUpload) {
   // multipart
} else {
  // not multipart
}

[juliusknorr]

Seems good, do you know what s3 providers/solutions enforce such a limit?

[juliusknorr]

Why don't test if MultiPart is supported?

It might need a different interface, I'm not sure if all providers that support multipart upload also support multipart copy

[icewind1991]

do you know what s3 providers/solutions enforce such a limit?

No, but there are at least 2 different cases where the multipart copy is failing

Why don't test if MultiPart is supported? Something like:

I'm not aware of any good way to tell if an S3 implementation supports it

[Ziyann]

For reference, I'm also affected by this issue, using Google Cloud Storage (but haven't tested this patch yet). Some built-in solution would be greatly appreciated, either a configurable limit like copySizeLimit here (which we could set to a very high value, thus never triggering multipart copy), or even better, some enable/disable switches for the various operations, because right now I'm manually reverting #40577 on production after upgrades.
There are many S3 providers with different features supported, so I think it would be great to have as many configuration options as possible (avoiding manual file changes on production).

[Ziyann]

You should propagate copySizeLimit to the S3 SDK (mup_threshold), otherwise, it will use the hardcoded 5 GB threshold at some places: https://github.com/nextcloud/3rdparty/blob/v28.0.0/aws/aws-sdk-php/src/S3/ObjectCopier.php#L96-L103
See: #42068 (comment)

[juliusknorr]

Pushed an additional commit to be able to fully turn off multipart copy for s3 providers not supporting it at all.