[PATCH 6/8] fs/configfs: add 'fill_subsystem' and 'clear_subsystem' callbacks
Hannes Reinecke
hare at kernel.org
Sat Jun 13 04:14:35 PDT 2026
When creating a new per-namespace filesystem static initialisation
doesn't work, so implement a 'fill_subsystem' and 'clear_subsystem'
callbacks to 'struct configfs_subsystem' to allow for every driver
to populate the subsystem structure dynamicall.
Signed-off-by: Hannes Reinecke <hare at kernel.org>
---
fs/configfs/configfs_internal.h | 4 ++
fs/configfs/dir.c | 90 ++++++++++++++++++++++++++++++++-
fs/configfs/mount.c | 6 +++
include/linux/configfs.h | 5 ++
4 files changed, 103 insertions(+), 2 deletions(-)
diff --git a/fs/configfs/configfs_internal.h b/fs/configfs/configfs_internal.h
index a91e97194c3d..7992a7da3de6 100644
--- a/fs/configfs/configfs_internal.h
+++ b/fs/configfs/configfs_internal.h
@@ -94,6 +94,10 @@ extern struct dentry *configfs_pin_fs(struct super_block *sb);
extern void configfs_release_fs(struct super_block *sb);
extern struct configfs_super_info *configfs_get_super_info(u64 ns_id);
extern void configfs_put_super_info(struct configfs_super_info *info);
+extern void configfs_link_subsystems(struct super_block *sb,
+ struct configfs_super_info *info);
+extern void configfs_unlink_subsystems(struct super_block *sb,
+ struct configfs_super_info *info);
extern const struct file_operations configfs_dir_operations;
extern const struct file_operations configfs_file_operations;
diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c
index 6e111e3fd0e0..bf59165acec7 100644
--- a/fs/configfs/dir.c
+++ b/fs/configfs/dir.c
@@ -1902,15 +1902,81 @@ int configfs_register_subsystem(struct configfs_subsystem *subsys)
goto out_put;
}
+ if (subsys->fill_subsystem) {
+ err = subsys->fill_subsystem(subsys, info->ns_id);
+ if (err)
+ goto out_release;
+ }
+
err = configfs_link_root(info, subsys, root);
+ if (err) {
+ subsys->clear_subsystem(subsys, info->ns_id);
+ goto out_put;
+ }
+
+ mutex_lock(&info->subsys_mutex);
+ list_add(&subsys->su_link, &info->subsys_list);
+ mutex_unlock(&info->subsys_mutex);
+
+out_release:
if (err)
configfs_release_fs(NULL);
-
out_put:
configfs_put_super_info(info);
return err;
}
+void configfs_link_subsystems(struct super_block *sb,
+ struct configfs_super_info *info)
+{
+ struct configfs_subsystem *s;
+ struct configfs_super_info *parent = configfs_get_super_info(0);
+
+ if (WARN_ON(IS_ERR(parent)))
+ return;
+ if (WARN_ON(parent == info))
+ return;
+ mutex_lock(&parent->subsys_mutex);
+ list_for_each_entry(s, &parent->subsys_list, su_link) {
+ struct configfs_subsystem *subsys;
+ struct dentry *root;
+ int err;
+
+ if (!s->fill_subsystem)
+ continue;
+ subsys = kzalloc_obj(*subsys);
+ if (!subsys)
+ continue;
+ subsys->fill_subsystem = s->fill_subsystem;
+ subsys->clear_subsystem = s->clear_subsystem;
+ INIT_LIST_HEAD(&subsys->su_link);
+ mutex_init(&subsys->su_mutex);
+ err = subsys->fill_subsystem(subsys, info->ns_id);
+ if (err) {
+ kfree(subsys);
+ continue;
+ }
+ root = configfs_pin_fs(sb);
+ if (IS_ERR(root)) {
+ subsys->clear_subsystem(subsys, info->ns_id);
+ kfree(subsys);
+ continue;
+ }
+ err = configfs_link_root(info, subsys, root);
+ if (err) {
+ configfs_release_fs(sb);
+ subsys->clear_subsystem(subsys, info->ns_id);
+ kfree(subsys);
+ continue;
+ }
+ mutex_lock(&info->subsys_mutex);
+ list_add(&subsys->su_link, &info->subsys_list);
+ mutex_unlock(&info->subsys_mutex);
+ }
+ mutex_unlock(&parent->subsys_mutex);
+ configfs_put_super_info(parent);
+}
+
static void configfs_unlink_root(struct configfs_subsystem *subsys)
{
struct config_group *group = &subsys->su_group;
@@ -1952,6 +2018,24 @@ static void configfs_unlink_root(struct configfs_subsystem *subsys)
dput(dentry);
}
+void configfs_unlink_subsystems(struct super_block *sb,
+ struct configfs_super_info *info)
+{
+ struct configfs_subsystem *subsys, *s;
+
+ mutex_lock(&info->subsys_mutex);
+ list_for_each_entry_safe(subsys, s, &info->subsys_list, su_link) {
+ list_del_init(&subsys->su_link);
+ configfs_unlink_root(subsys);
+ if (subsys->clear_subsystem)
+ subsys->clear_subsystem(subsys, info->ns_id);
+ unlink_group(&subsys->su_group);
+ configfs_release_fs(sb);
+ kfree(subsys);
+ }
+ mutex_unlock(&info->subsys_mutex);
+}
+
void configfs_unregister_subsystem(struct configfs_subsystem *subsys)
{
struct configfs_super_info *info = configfs_get_super_info(0);
@@ -1959,9 +2043,11 @@ void configfs_unregister_subsystem(struct configfs_subsystem *subsys)
if (WARN_ON(IS_ERR(info)))
return;
-
mutex_lock(&info->subsys_mutex);
+ list_del_init(&subsys->su_link);
configfs_unlink_root(subsys);
+ if (subsys->clear_subsystem)
+ subsys->clear_subsystem(subsys, info->ns_id);
unlink_group(group);
mutex_unlock(&info->subsys_mutex);
configfs_release_fs(NULL);
diff --git a/fs/configfs/mount.c b/fs/configfs/mount.c
index 8cf4bda14bec..8de3ae0cb6dd 100644
--- a/fs/configfs/mount.c
+++ b/fs/configfs/mount.c
@@ -142,6 +142,10 @@ static int configfs_fill_super(struct super_block *sb, struct fs_context *fc)
sb->s_fs_info = info;
set_default_d_op(sb, &configfs_dentry_ops); /* the rest get that */
sb->s_d_flags |= DCACHE_DONTCACHE;
+
+ pr_info("%s: ns %llu\n", __func__, info->ns_id);
+ configfs_link_subsystems(sb, info);
+
return 0;
}
@@ -164,6 +168,8 @@ static void configfs_kill_sb(struct super_block *sb)
{
struct configfs_super_info *info = sb->s_fs_info;
+ pr_info("%s: ns %llu\n", __func__, info->ns_id);
+ configfs_unlink_subsystems(sb, info);
kill_anon_super(sb);
configfs_put_super_info(info);
sb->s_fs_info = NULL;
diff --git a/include/linux/configfs.h b/include/linux/configfs.h
index ef65c75beeaa..ce88da5bdcec 100644
--- a/include/linux/configfs.h
+++ b/include/linux/configfs.h
@@ -226,8 +226,13 @@ struct configfs_group_operations {
};
struct configfs_subsystem {
+ struct list_head su_link;
struct config_group su_group;
struct mutex su_mutex;
+ int (*fill_subsystem)(struct configfs_subsystem *subsys,
+ u64 ns_id);
+ void (*clear_subsystem)(struct configfs_subsystem *subsys,
+ u64 ns_id);
};
static inline struct configfs_subsystem *to_configfs_subsystem(struct config_group *group)
--
2.51.0
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