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SubjectRe: [PATCH] quota: code cleanup for hash bits calculation
 ---- 在 星期一, 2019-09-23 18:02:53 Jan Kara <jack@suse.cz> 撰写 ----
> On Sat 21-09-19 09:56:28, Chengguang Xu wrote:
> > Code cleanup for hash bits calculation by
> > calling rounddown_pow_of_two() and ilog2()
> >
> > Signed-off-by: Chengguang Xu <cgxu519@zoho.com.cn>
>
> Thanks for the patch! One comment below:
>
> > diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
> > index 6e826b454082..679dd3b5db70 100644
> > --- a/fs/quota/dquot.c
> > +++ b/fs/quota/dquot.c
> > @@ -2983,13 +2983,9 @@ static int __init dquot_init(void)
> >
> > /* Find power-of-two hlist_heads which can fit into allocation */
> > nr_hash = (1UL << order) * PAGE_SIZE / sizeof(struct hlist_head);
> > - dq_hash_bits = 0;
> > - do {
> > - dq_hash_bits++;
> > - } while (nr_hash >> dq_hash_bits);
> > - dq_hash_bits--;
> > + nr_hash = rounddown_pow_of_two(nr_hash);
> > + dq_hash_bits = ilog2(nr_hash);
> >
> > - nr_hash = 1UL << dq_hash_bits;
> Why not just:
> dq_hash_bits = ilog2(nr_hash);
> nr_hash = 1UL << dq_hash_bits;
>
> That way we need to compute fls() only once...

Yeah, you are right, I'll update in v2.

Thanks,
Chengguang

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