On Fri, Jun 5, 2020 at 7:23 AM Rasmus Villemoes
<linux@xxxxxxxxxxxxxxxxxx> wrote:
>
> + /*
> + * If the "group" and "other" permissions are the same,
> + * there's no point calling in_group_p() to decide which
> + * set to use.
> + */
> + if ((((mode >> 3) ^ mode) & 7) && in_group_p(inode->i_gid))
> mode >>= 3;
Ugh. Not only is this ugly, but it's not even the best optimization.
We don't care that group and other match exactly. We only care that
they match in the low 3 bits of the "mask" bits.
So if we want this optimization - and it sounds worth it - I think we
should do it right. But I also think it should be written more
legibly.
And the "& 7" is the same "& (MAY_READ | MAY_WRITE | MAY_EXEC)" we do later.
In other words, if we do this, I'd like it to be done even more
aggressively, but I'd also like the end result to be a lot more
readable and have more comments about why we do that odd thing.
Something like this *UNTESTED* patch, perhaps?
I might have gotten something wrong, so this would need
double-checking, but if it's right, I find it a _lot_ more easy to
understand than making one expression that is pretty complicated and
opaque.
Hmm?
Linus
Attachment:
patch
Description: Binary data
