Re: [PATCH] fs/ceph/super: add mount options "snapdir{mode,uid,gid}"

Max Kellermann
2022-10-25T10:04:18Z

On Tue, Oct 25, 2022 at 11:10 AM Xiubo Li <xiubli@redhat.com> wrote:
> $ sudo ./bin/mount.ceph privileged@.a=/ /mnt/privileged/mountpoint
>
> $ sudo ./bin/mount.ceph global@.a=/ /mnt/global/mountpoint

So you have two different mount points where different client
permissions are used. There are various problems with that
architecture:

- it complicates administration, because now every mount has to be done twice
- it complicates applications accessing ceph (and their
configuration), because there are now 2 mount points
- it increases resource usage for having twice as many ceph connections
- it interferes with fscache, doubling fscache's local disk usage,
reducing fscache's efficiency
- ownership of the snapdir is still the same as the parent directory,
and I can't have non-superuser processes to manage snapshots; all
processes mananging snapshots need to have write permission on the
parent directory
- this is still all-or-nothing; I can't forbid users to list (+r) or
access (+x) snapshots

All those problems don't exist with my patch.