[PATCH v9 13/25] security: Introduce file_release hook

[Al Viro]

On Mon, Jan 15, 2024 at 07:17:57PM +0100, Roberto Sassu wrote:
> From: Roberto Sassu <roberto.sassu at huawei.com>
> 
> In preparation for moving IMA and EVM to the LSM infrastructure, introduce
> the file_release hook.
> 
> IMA calculates at file close the new digest of the file content and writes
> it to security.ima, so that appraisal at next file access succeeds.
> 
> An LSM could implement an exclusive access scheme for files, only allowing
> access to files that have no references.

Elaborate that last part, please.