ovl: remove ovl_revert_creds()

The wrapper isn't needed anymore. Overlayfs completely relies on its
cleanup guard.

Link: https://patch.msgid.link/20251117-work-ovl-cred-guard-v4-42-b31603935724@kernel.org
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>

Author: brauner

fs/overlayfs/overlayfs.h

@@ -455,7 +455,6 @@ int ovl_want_write(struct dentry *dentry);
 void ovl_drop_write(struct dentry *dentry);
 struct dentry *ovl_workdir(struct dentry *dentry);
 const struct cred *ovl_override_creds(struct super_block *sb);
-void ovl_revert_creds(const struct cred *old_cred);
 
 EXTEND_CLASS(override_creds, _ovl, ovl_override_creds(sb), struct super_block *sb)
 

fs/overlayfs/util.c

@@ -69,11 +69,6 @@ const struct cred *ovl_override_creds(struct super_block *sb)
 	return override_creds(ofs->creator_cred);
 }
 
-void ovl_revert_creds(const struct cred *old_cred)
-{
-	revert_creds(old_cred);
-}
-
 /*
  * Check if underlying fs supports file handles and try to determine encoding
  * type, in order to deduce maximum inode number used by fs.