sysfs: create bin_attributes under the requested group

bin_attributes created/updated in create_files() (such as those listed
via (struct device).attribute_groups) were not placed under the
specified group, and instead appeared in the base kobj directory.

Fix this by making bin_attributes use creating code similar to normal
attributes.

A quick grep shows that no one is using bin_attrs in a named attribute
group yet, so we can do this without breaking anything in usespace.

Note that I do not add is_visible() support to
bin_attributes, though that could be done as well.

This is a copy of the patch already merged in Greg's tree.

Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

fs/sysfs/group.c

@@ -70,8 +70,11 @@ static int create_files(struct kernfs_node *parent, struct kobject *kobj,
 	if (grp->bin_attrs) {
 		for (bin_attr = grp->bin_attrs; *bin_attr; bin_attr++) {
 			if (update)
-				sysfs_remove_bin_file(kobj, *bin_attr);
-			error = sysfs_create_bin_file(kobj, *bin_attr);
+				kernfs_remove_by_name(parent,
+						(*bin_attr)->attr.name);
+			error = sysfs_add_file_mode_ns(parent,
+					&(*bin_attr)->attr, true,
+					(*bin_attr)->attr.mode, NULL);
 			if (error)
 				break;
 		}