On Mon, Aug 20, 2018 at 6:21 PM Luis Henriques <lhenriques@xxxxxxxx> wrote:
>
> Hi!
>
> This series is my initial attempt at getting a copy_file_range syscall
> implementation in the kernel cephfs client using the 'copy-from' RADOS
> operation.
>
> The idea of getting this implemented was from Greg -- or, at least, he
> created a feature in the tracker [1]. I just decided to give it a try
> as the feature wasn't assigned to anyone ;-)
>
> I have this patchset sitting on my laptop for a while already, waiting
> for me to revisit it, review some of its TODOs... but I finally decided
> to send it out as-is instead, to get some early feedback.
>
> The first patch implements the copy-from operation in the libceph
> module. Unfortunately, the documentation for this operation is
> nonexistent and I had to do a lot of digging to figure out the details
> (and I probably I missed something!). For example, initially I was
> hoping that this operation could be used to copy more than one object at
> the time. Doing an OSD request per object copy is not ideal, but
> unfortunately it seems to be the only way. Anyway, my expectations are
> that this new operation will be useful for other features in the future.
A single OSD request can contain multiple OSD ops. In the kernel
client, this number is currently limited to 16 (CEPH_OSD_MAX_OPS).
Thanks,
Ilya
