vfs: push dentry_unhash on rmdir into file systems

Only a few file systems need this.  Start by pushing it down into each
fs rmdir method (except gfs2 and xfs) so it can be dealt with on a per-fs
basis.

This does not change behavior for any in-tree file systems.

Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sage Weil <sage@newdream.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index c6ba49b..40d5c2a 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -667,6 +667,8 @@
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
+	dentry_unhash(entry);
+
 	req->in.h.opcode = FUSE_RMDIR;
 	req->in.h.nodeid = get_node_id(dir);
 	req->in.numargs = 1;