fs: export mnt_idmap_get/mnt_idmap_put

These helpers are required to support idmapped mounts in CephFS.

Cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

fs/mnt_idmapping.c

@@ -256,6 +256,7 @@ struct mnt_idmap *mnt_idmap_get(struct mnt_idmap *idmap)
 
 	return idmap;
 }
+EXPORT_SYMBOL_GPL(mnt_idmap_get);
 
 /**
  * mnt_idmap_put - put a reference to an idmapping
@@ -271,3 +272,4 @@ void mnt_idmap_put(struct mnt_idmap *idmap)
 		kfree(idmap);
 	}
 }
+EXPORT_SYMBOL_GPL(mnt_idmap_put);

include/linux/mnt_idmapping.h

@@ -115,6 +115,9 @@ static inline bool vfsgid_eq_kgid(vfsgid_t vfsgid, kgid_t kgid)
 
 int vfsgid_in_group_p(vfsgid_t vfsgid);
 
+struct mnt_idmap *mnt_idmap_get(struct mnt_idmap *idmap);
+void mnt_idmap_put(struct mnt_idmap *idmap);
+
 vfsuid_t make_vfsuid(struct mnt_idmap *idmap,
 		     struct user_namespace *fs_userns, kuid_t kuid);