9:49 a.m.
On Thu, Apr 4, 2019 at 11:41 AM Wyllys Ingersoll
<wyllys.ingersoll(a)keepertech.com> wrote:
>
> I have a cephfs filesystem and I want to export a subdirectory of my cephfs
tree. Is this possible or do I have to export the entire tree from the root?
>
You can export a subdirectory, but there is no subtree checking. It's possible for
someone to guess filehandles and access files outside the exported directory.
See the "no_subtree_check" section in the linux
exports(5) manpage. It is generally best to export along filesystem boundaries
for that reason.
> If it is possible, then is it also possible to define exports for multiple
subdirectories of my cephfs FS such as /cephfs/exports/foo and
/cephfs/exports/bar as 2 separate exports?
Yes. They will each get their own cephfs client though, so in the event that two
clients end up accessing the same inodes via two different exports, performance
may suffer. The clients will end up competing with one another for caps.
Hmm, if this was something we actually wanted to generally support (I'm not convinced
it would be a good idea), we could use the fsal_filesystem infrastructure to share the
cephfs client.
Frank