Tom Lendacky wrote:
In order to support dynamic decisions as to whether an attribute should be
created, add a callback that returns a bool to indicate whether the
attribute should be displayed. If no callback is registered, the attribute
is displayed by default.
Cc: Joel Becker <jlbec@xxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Co-developed-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Signed-off-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
---
fs/configfs/dir.c | 20 ++++++++++++++++++++
include/linux/configfs.h | 3 +++
2 files changed, 23 insertions(+)
diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c
index 18677cd4e62f..463e66258507 100644
--- a/fs/configfs/dir.c
+++ b/fs/configfs/dir.c
@@ -580,6 +580,7 @@ static void detach_attrs(struct config_item * item)
static int populate_attrs(struct config_item *item)
{
const struct config_item_type *t = item->ci_type;
+ struct configfs_group_operations *ops;
struct configfs_attribute *attr;
struct configfs_bin_attribute *bin_attr;
int error = 0;
@@ -587,14 +588,33 @@ static int populate_attrs(struct config_item *item)
if (!t)
return -EINVAL;
+
+ ops = t->ct_group_ops;
+ if (!ops) {
+ struct config_group *g = item->ci_group;
+
+ /*
+ * No item specific group operations, check if the item's group
+ * has group operations.
+ */
+ if (g && g->cg_item.ci_type)
+ ops = g->cg_item.ci_type->ct_group_ops;
Oh, I would not have expected to need to consider any alternate group
ops for attribute visibility beyond t->ct_group_ops. However in my RFC
example I made this mistake:
static struct configfs_group_operations tsm_report_group_ops = {
.make_item = tsm_report_make_item,
+ .is_visible = tsm_report_attr_visible,
+ .is_bin_visible = tsm_report_bin_attr_visible,
};
Which in retrospect is the wrong level, and I suspect only reachable if
you do the the above awkward indirection ("ops =
g->cg_item.ci_type->ct_group_ops"). Instead, I was expecting symmetry
with sysfs where the object that carries ->attrs also carries
->is_visible, so something like this:
+ static struct configfs_group_operations tsm_report_attr_group_ops = {
+ .is_visible = tsm_report_attr_visible,
+ .is_bin_visible = tsm_report_bin_attr_visible,
+ };
const struct config_item_type tsm_report_type = {
.ct_owner = THIS_MODULE,
.ct_bin_attrs = tsm_report_bin_attrs,
.ct_attrs = tsm_report_attrs,
.ct_item_ops = &tsm_report_item_ops,
+ .ct_group_ops = &tsm_report_attr_group_ops
};
EXPORT_SYMBOL_GPL(tsm_report_default_type);
..because is_visible() at the g->cg_item.ci_type->ct_group_ops level
would seem to mean parent directory visibility which is mismatched.
However as I stare at this a bit more it sinks in that configfs "group"
!= sysfs "group". So I am open to the suggestion that ci_item_ops is the
right place to house item attribute visibility callbacks, or even a new
"ci_attr_ops" expressly for this purpose. Either way my expectation is
that config_item_type can get to the visibilty callbacks for its
attributes without needing to traverse any other groups or items.