Re: [PATCH v2 2/2] ceph: quota: fix quota subdir mounts

[Luis Henriques]

"Yan, Zheng" <ukernel@xxxxxxxxx> writes:

> On Mon, Mar 18, 2019 at 5:06 PM Gregory Farnum <gfarnum@xxxxxxxxxx> wrote:
>>
>> On Mon, Mar 18, 2019 at 2:32 PM Yan, Zheng <ukernel@xxxxxxxxx> wrote:
>> > After reading the code carefully. I feel a little uncomfortable with
>> > the "lookup_ino" in get_quota_realm.  how about populating directories
>> > above the 'mount subdir' during mounting (similar to cifs_get_root ).

Wouldn't it be a problem if the directory layout (or, in this case, the
snaprealm layout) change during the mount lifetime?  In that case we
would need to do this lookup anyway.

>>
>> Isn't that going to be a problem for any clients which have
>>restricted filesystem access permissions? They may not be able to see
>>all the directories above their mount point.  -Greg
>
> using lookup_ino to get inode above the "mount subdir" has the same problem
>

In this case I believe we get an -EPERM from the MDS.  And then the
client simply falls back to the 'default' behaviour, which is to allow
the user to create/write to files as if there were no quotas set.

Cheers,
-- 
Luis