Re: [PATCH 0/3] ceph: use new mount device syntax

[Jeff Layton <jlayton@kernel.org>]

On Fri, 2021-06-04 at 10:35 +0530, Venky Shankar wrote:
> This series introduces changes Ceph File System mount device string.
> Old mount device syntax (source) has the following problems:
> 
> mounts to the same cluster but with different fsnames
> and/or creds have identical device string which can
> confuse xfstests.
> 
> Userspace mount helper tool resolves monitor addresses
> and fill in mon addrs automatically, but that means the
> device shown in /proc/mounts is different than what was
> used for mounting.
> 
> New device syntax is as follows:
> 
>   cephuser@mycephfs2=/path
> 
> Note, there is no "monitor address" in the device string.
> That gets passed in as mount option. This keeps the device
> string same when monitor addresses change (on remounts).
> 
> Also note that the userspace mount helper tool is backward
> compatible. I.e., the mount helper will fallback to using
> old syntax after trying to mount with the new syntax.
> 
> The user space mount helper changes are here:
> 
>     http://github.com/ceph/ceph/pull/41334
> 
> 
> Venky Shankar (3):
>   ceph: new device mount syntax
>   ceph: record updated mon_addr on remount
>   doc: document new CephFS mount device syntax
> 
>  Documentation/filesystems/ceph.rst | 16 +++++--
>  fs/ceph/super.c                    | 75 +++++++++++++++++++++---------
>  fs/ceph/super.h                    |  1 +
>  3 files changed, 67 insertions(+), 25 deletions(-)
> 

Nice work, Venky!

This looks good at first glance. The only real issue I see is that we
can't just deprecate the mds_namespace option. I think we have to keep
that around for now for the case of a legacy mount helper.

I'll plan to pull down this and your userland patches and give them a
spin later today.

Cheers,
-- 
Jeff Layton <jlayton@kernel.org>