Re: [PATCH 4/5] ceph: fix improper use of smp_mb__before_atomic()

Yan, Zheng
2019-05-13T13:04:21Z

On 5/10/19 4:55 AM, Andrea Parri wrote:
> On Tue, Apr 30, 2019 at 05:08:43PM +0800, Yan, Zheng wrote:
>> On Tue, Apr 30, 2019 at 4:26 PM Peter Zijlstra <peterz@infradead.org> wrote:
>>>
>>> On Mon, Apr 29, 2019 at 10:15:00PM +0200, Andrea Parri wrote:
>>>> This barrier only applies to the read-modify-write operations; in
>>>> particular, it does not apply to the atomic64_set() primitive.
>>>>
>>>> Replace the barrier with an smp_mb().
>>>>
>>>
>>>> @@ -541,7 +541,7 @@ static inline void __ceph_dir_set_complete(struct ceph_inode_info *ci,
>>>> long long release_count,
>>>> long long ordered_count)
>>>> {
>>>> - smp_mb__before_atomic();
>>>
>>> same
>>> /*
>>> * XXX: the comment that explain this barrier goes here.
>>> */
>>>
>>
>> makes sure operations that setup readdir cache (update page cache and
>> i_size) are strongly ordered with following atomic64_set.
>
> Thanks for the suggestion, Yan.
>
> To be clear: would you like me to integrate your comment and resend?
> any other suggestions?
>

Yes, please

Regards
Yan, Zheng

> Thanx,
> Andrea
>
>
>>
>>>> + smp_mb();
>>>
>>>> atomic64_set(&ci->i_complete_seq[0], release_count);
>>>> atomic64_set(&ci->i_complete_seq[1], ordered_count);
>>>> }
>>>> --
>>>> 2.7.4
>>>>