mdcache: change replay trimming a bit.
mdcache: change replay trimming a bit.

Previously we were re-inserting dentrys on the open list. But if
there weren't any other available dentrys to trim, this could
have led to an infinite loop!
Now, we save them in a list and pop them back in once the trim
is done.

Signed-off-by: Greg Farnum <7c97bbd3e62ab6303ee1daebcbc2d9d58823df1a@hq.newdream.net>

ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph