Comment 7 for bug 1124250

@denys.duchier As I understood by reading the code, this is not a bug but a feature. In Linux 3.4 they dropped their own B-tree uid/username caching in favor of the "key" infrastructure which, by design, includes quota. While this is a pain in this case, it mitigates the risk of DOS attack by filling up kernel's memory.

I saw 2 options:
 1/ increase root's quota as explained by @wolfgang-walter
 2/ fallback to (poorly documented) nfs3 like behavior

I personally did the later. In this scheme, uids are sent over the wire as equivalent strings ie username="123" for uid=123 instead of mapping it to "<email address hidden>". The other end *should* detect it is a stringified uid and convert it back. This is all the magic. I said "should" as it actually depends on the exact implementation since this is fallback behavior instead of standard. It works with Linux and, with reasonable effort, with Solaris.