mm/damon/sysfs-schemes: return error when for attempts to install filters on wrong...

Return error if the user tries to install a DAMOS filter on DAMOS filters
sysfs directory that assumed to be used for filters that handled by a
DAMON layer that not same to that for the installing filter.

Link: https://lkml.kernel.org/r/20250305222733.59089-7-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index e4e36c34ec0e5f4e4e8651153600845eb0232849..1895d2d2c29501a82ed4b46c7c199d1f3d39bc1c 100644 (file)
--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -362,6 +362,23 @@ static ssize_t type_show(struct kobject *kobj,
                        damon_sysfs_scheme_filter_type_strs[filter->type]);
 }
 
+static bool damos_sysfs_scheme_filter_valid_type(
+               enum damos_sysfs_filter_handle_layer layer,
+               enum damos_filter_type type)
+{
+       switch (layer) {
+       case DAMOS_SYSFS_FILTER_HANDLE_LAYER_BOTH:
+               return true;
+       case DAMOS_SYSFS_FILTER_HANDLE_LAYER_CORE:
+               return !damos_filter_for_ops(type);
+       case DAMOS_SYSFS_FILTER_HANDLE_LAYER_OPS:
+               return damos_filter_for_ops(type);
+       default:
+               break;
+       }
+       return false;
+}
+
 static ssize_t type_store(struct kobject *kobj,
                struct kobj_attribute *attr, const char *buf, size_t count)
 {
@@ -373,6 +390,9 @@ static ssize_t type_store(struct kobject *kobj,
        for (type = 0; type < NR_DAMOS_FILTER_TYPES; type++) {
                if (sysfs_streq(buf, damon_sysfs_scheme_filter_type_strs[
                                        type])) {
+                       if (!damos_sysfs_scheme_filter_valid_type(
+                                               filter->handle_layer, type))
+                               break;
                        filter->type = type;
                        ret = count;
                        break;