[PATCH] knfsd: nfsd4: grant delegations more frequently

Keep unused openowners around for at least one lease period, to avoid the need
for as many open confirmations and to allow handing out more delegations.

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>