On Thu, 2019-11-14 at 10:57 +0000, Luis Henriques wrote:
> Hi!
>
> So, after the feedback I got from v1 [1] I've sent out a pull-request
> for the OSDs [2] which encodes require_osd_release into the OSDMap
> client data. This allows the client to figure out which ceph release
> the OSDs cluster is running and decide whether or not it's safe to use
> the copy-from Op for copy_file_range.
>
> This new patchset I'm sending simply adds enough functionality to the
> kernel client so that it can take advantage of this OSD patch:
>
> 0001 - adds the ability to decode TYPE_MSGR2 addresses. This is a
> required functionality for enabling SERVER_NAUTILUS in the
> client. I hope I got the new format right, as I couldn't figure
> out what the hard-coded values (see comments) really mean.
>
nit: the first 3 patch subject lines should probably be prefixed with
"libceph:"
> 0002 - allows the client to retrieve the new require_osd_release field
> from the OSDMap if available. This patch also adds SERVER_MIMIC,
> SERVER_NAUTILUS and SERVER_OCTOPUS to the supported features,
> which TBH I'm not sure if that's a safe thing to do -- the only
> issue I've seen was that Nautilus requires the ability to decode
> TYPE_MSGR2 address, but I may have missed others.
>
Yes, this needs to be done with care. We have to ensure that the server
side isn't assuming that the client supports something that it doesn't.
I think that means just trawling through the code and verifying whether
this is safe.
> 0003 - debug code to add require_osd_release to the osdmap debugfs file.
>
> 0004 - adds the truncate_{seq,size} fields to the 'copy-from' operation
> if the OSDs are >= Octopus.
>
> Also note that, as suggested by Ilya, I've dropped the patch that would
> change the default mount options to 'copyfrom'.
>
> These patches have been tested with the xfstests generic test suite, and
> with a couple of other (local) tests that exercise the cephfs
> copy_file_range syscall. I didn't saw any issues, but as I said above,
> I'm not really sure if adding the SERVER_* flags to the supported
> features have other side effects.
>
> [1] https://lore.kernel.org/lkml/20191108141555.31176-1-lhenriques@xxxxxxxx/
> [2] https://github.com/ceph/ceph/pull/31611
>
I'm just getting caught up on the discussion here, but why was it
decided to do it this way instead of just adding a new OSD
"copy-from-no-truncseq" operation? Once you tried it once and an OSD
didn't support it, you could just give up on using it any longer? That
seems a lot simpler than trying to monkey with feature bits.
--
Jeff Layton <jlayton@xxxxxxxxxx>
