[Lustre-devel] Queries regarding LDLM_ENQUEUE

[bzzz.tomas at gmail.com <bzzz.tomas@gmail.com>]

On 10/20/10 12:24 PM, Andreas Dilger wrote:
> I'm reluctant to expose the whole FID namespace to applications, since this completely bypasses all directory permissions and allows opening files only based on their inode permissions.  If we require a name_to_handle() syscall to succeed first, before allowing open_by_handle() to work, then at least we know that one of the involved processes was able to do a full path traversal.

yes, this is a good point. can be solved if you use FID +
capability/signature ?

>> another idea was to do whole path traversal on MDS within a single RPC.
>> bug that'd require amount of changes to llite and/or VFS and keep MDS
>> a bottleneck.
>
> This was discussed a long time ago, and has the potential drawback that if one of the path components is over-mounted on the client (e.g. local RAM-based tmpfs on a Lustre root filesystem) then the MDS-side path traversal would be incorrect.  It could return an entry underneath the mountpoint, instead of inside it.

yes, and that could be solved if server returns a series of FIDs,
then client could check whether any of those is over-mounted?

thanks, z