vfs: push dentry_unhash on rename_dir into file systems

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

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 40d5c2a..e462a7a 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -693,6 +693,10 @@
 	struct fuse_rename_in inarg;
 	struct fuse_conn *fc = get_fuse_conn(olddir);
 	struct fuse_req *req = fuse_get_req(fc);
+
+	if (newent->d_inode && S_ISDIR(newent->d_inode->i_mode))
+		dentry_unhash(newent);
+
 	if (IS_ERR(req))
 		return PTR_ERR(req);