[PATCH] v9fs: fix overzealous dropping of dentry which breaks dcache

There is a d_drop in dir_release which caused problems as it invalidates
dcache entries too soon.  This was likely a part of the wierd cwd behavior
folks were seeing.

Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>