Always lookup priv_root on reiserfs mount and keep it

... even if it's a negative dentry.  That way we can set ->d_op on
root before anyone could race with us.  Simplify d_compare(), while
we are at it.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/reiserfs/super.c b/fs/reiserfs/super.c
index 0ae6486..d444fe0 100644
--- a/fs/reiserfs/super.c
+++ b/fs/reiserfs/super.c
@@ -1842,7 +1842,8 @@
 			goto error;
 		}
 
-		if ((errval = reiserfs_xattr_init(s, s->s_flags))) {
+		if ((errval = reiserfs_lookup_privroot(s)) ||
+		    (errval = reiserfs_xattr_init(s, s->s_flags))) {
 			dput(s->s_root);
 			s->s_root = NULL;
 			goto error;
@@ -1855,7 +1856,8 @@
 			reiserfs_info(s, "using 3.5.x disk format\n");
 		}
 
-		if ((errval = reiserfs_xattr_init(s, s->s_flags))) {
+		if ((errval = reiserfs_lookup_privroot(s)) ||
+		    (errval = reiserfs_xattr_init(s, s->s_flags))) {
 			dput(s->s_root);
 			s->s_root = NULL;
 			goto error;