libcephfs: Open-By-Handle API question

libcephfs: Open-By-Handle API question

[Ilya Storozhilov]

Hi Ceph developers,

in order to represent NFS-frontend to CephFS data storage we are trying to use innovative Open-By-Handle API from 'src/include/cephfs/libcephfs.h' file, which is of 'wip-libcephfs' branch at the moment. API looks quite consistent and useful but we couldn't find a method to get a pointer to root inode of the mounted Ceph filesystem.

At the moment we have found only one place, where it could be fetched from: an 'Inode* root' member from the 'Client' class ('src/client/Client.h') but it is in 'protected' section, so some hack is needed (e.g. to introduce a Client's descendant, which is providing a method to acces this protected member). Do you know, how to fetch a pointer to the root inode of the mounted Ceph filesystem without any hacking (using just an official CephFS API only)?

Thank you and best wishes,
Ilya V. Storozhilov
EPAM Systems
Lead Software Engineer

P.S. What do you think about to make 'Open-By-Handle' API to be a primary and not low-level API to CephFS and to make POSIX-like API to be just a helper addendum to it?

Re: libcephfs: Open-By-Handle API question

[Matt W. Benjamin]

Hi Ilya,

The changes on this branch originated in our Ganesha NFS driver for
Ceph, so I'm not sure where the gap is, if any.

I'll send an update to the list when we've finish re-integrating against
the libcephfs-wip merge branch.

Matt

----- "Ilya Storozhilov" <Ilya_Storozhilov@epam.com> wrote:

> Hi Ceph developers,
> 
> in order to represent NFS-frontend to CephFS data storage we are
> trying to use innovative Open-By-Handle API from
> 'src/include/cephfs/libcephfs.h' file, which is of 'wip-libcephfs'
> branch at the moment. API looks quite consistent and useful but we
> couldn't find a method to get a pointer to root inode of the mounted
> Ceph filesystem.
> 
> At the moment we have found only one place, where it could be fetched
> from: an 'Inode* root' member from the 'Client' class
> ('src/client/Client.h') but it is in 'protected' section, so some hack
> is needed (e.g. to introduce a Client's descendant, which is providing
> a method to acces this protected member). Do you know, how to fetch a
> pointer to the root inode of the mounted Ceph filesystem without any
> hacking (using just an official CephFS API only)?
> 
> Thank you and best wishes,
> Ilya V. Storozhilov
> EPAM Systems
> Lead Software Engineer
> 
> P.S. What do you think about to make 'Open-By-Handle' API to be a
> primary and not low-level API to CephFS and to make POSIX-like API to
> be just a helper addendum to it?--
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