[PATCH v2 1/3] fs: configfs: add helper to identify configfs paths

[Runyu Xiao]

Several nvmet paths need to identify configfs-backed resolved paths while
already running under configfs callbacks. Keep the classification in
configfs itself so callers can reuse the filesystem-type test instead of
open-coding string comparisons.

Signed-off-by: Runyu Xiao <runyu.xiao at seu.edu.cn>
---
 fs/configfs/mount.c      | 6 ++++++
 include/linux/configfs.h | 2 ++
 2 files changed, 8 insertions(+)

diff --git a/fs/configfs/mount.c b/fs/configfs/mount.c
index 456c4a2efb53..1204421b61df 100644
--- a/fs/configfs/mount.c
+++ b/fs/configfs/mount.c
@@ -120,6 +120,12 @@ static struct file_system_type configfs_fs_type = {
 };
 MODULE_ALIAS_FS("configfs");
 
+bool configfs_path_is_configfs(const struct path *path)
+{
+	return path->dentry->d_sb->s_type == &configfs_fs_type;
+}
+EXPORT_SYMBOL_GPL(configfs_path_is_configfs);
+
 struct dentry *configfs_pin_fs(void)
 {
 	int err = simple_pin_fs(&configfs_fs_type, &configfs_mount,
diff --git a/include/linux/configfs.h b/include/linux/configfs.h
index 698520b1bfdb..b3426c952835 100644
--- a/include/linux/configfs.h
+++ b/include/linux/configfs.h
@@ -34,6 +34,7 @@ struct configfs_group_operations;
 struct configfs_attribute;
 struct configfs_bin_attribute;
 struct configfs_subsystem;
+struct path;
 
 struct config_item {
 	char			*ci_name;
@@ -243,6 +244,7 @@ void configfs_unregister_subsystem(struct configfs_subsystem *subsys);
 int configfs_register_group(struct config_group *parent_group,
 			    struct config_group *group);
 void configfs_unregister_group(struct config_group *group);
+bool configfs_path_is_configfs(const struct path *path);
 
 void configfs_remove_default_groups(struct config_group *group);
 
-- 
2.34.1