erofs_workgroup_put(&grp->obj);
 }
 
-void z_erofs_vle_work_release(struct z_erofs_vle_work *work)
+static void z_erofs_vle_work_release(struct z_erofs_vle_work *work)
 {
        struct z_erofs_vle_workgroup *grp =
                z_erofs_vle_work_workgroup(work, true);
 
 #include "unzip_vle.h"
 #include <linux/lz4.h>
 
-int z_erofs_unzip_lz4(void *in, void *out, size_t inlen, size_t outlen)
+static int z_erofs_unzip_lz4(void *in, void *out, size_t inlen, size_t outlen)
 {
        int ret = LZ4_decompress_safe_partial(in, out, inlen, outlen, outlen);
 
 
        __erofs_workgroup_free(grp);
 }
 
-bool erofs_try_to_release_workgroup(struct erofs_sb_info *sbi,
-                                   struct erofs_workgroup *grp,
-                                   bool cleanup)
+static bool erofs_try_to_release_workgroup(struct erofs_sb_info *sbi,
+                                          struct erofs_workgroup *grp,
+                                          bool cleanup)
 {
        /*
         * for managed cache enabled, the refcount of workgroups
 
 #else
 /* for nocache case, no customized reclaim path at all */
-bool erofs_try_to_release_workgroup(struct erofs_sb_info *sbi,
-                                   struct erofs_workgroup *grp,
-                                   bool cleanup)
+static bool erofs_try_to_release_workgroup(struct erofs_sb_info *sbi,
+                                          struct erofs_workgroup *grp,
+                                          bool cleanup)
 {
        int cnt = atomic_read(&grp->refcount);