On Thu, 31 Oct 2024 at 12:28, Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote:
>
> Anyway, patch looks sane; I still think that adding || !IS_POSIXACL(inode)
> wouldn't hurt (yes, it's a dereference of ->i_sb in case when ->i_acl
> is ACL_NOT_CACHED, but we are going to dereference it shortly after
> in case we don't take the fast path. OTOH, that probably matters only
> for fairly specific loads - massive accesses to procfs and sysfs, mostly.
Yeah, so the reason I'd like to avoid it is exactly that the i_sb
accesses are the ones that show up in profiles.
So I'd rather start with just the cheap inode-only "ACL is clearly not
there" check, and later if we find that the ACL_NOT_CACHED case is
problematic do we look at that.
Linus
