shmem_get_offset_ctx
simple_offset_init(shmem_get_offset_ctx(inode));
error = simple_offset_add(shmem_get_offset_ctx(dir), dentry);
ret = simple_offset_add(shmem_get_offset_ctx(dir), dentry);
simple_offset_remove(shmem_get_offset_ctx(dir), dentry);
error = simple_offset_add(shmem_get_offset_ctx(new_dir), new_dentry);
simple_offset_remove(shmem_get_offset_ctx(new_dir),
error = simple_offset_add(shmem_get_offset_ctx(dir), dentry);
simple_offset_remove(shmem_get_offset_ctx(dir), dentry);
simple_offset_destroy(shmem_get_offset_ctx(inode));
.get_offset_ctx = shmem_get_offset_ctx,