Re: [PATCH 1/4] fs: fix data invalidation in the cleancache during direct IO

[Andrey Ryabinin]

On 04/19/2017 01:46 AM, Andrew Morton wrote:
> On Fri, 14 Apr 2017 17:07:50 +0300 Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> wrote:
> 
>> Some direct write fs hooks call invalidate_inode_pages2[_range]()
>> conditionally iff mapping->nrpages is not zero. If page cache is empty,
>> buffered read following after direct IO write would get stale data from
>> the cleancache.
>>
>> Also it doesn't feel right to check only for ->nrpages because
>> invalidate_inode_pages2[_range] invalidates exceptional entries as well.
>>
>> Fix this by calling invalidate_inode_pages2[_range]() regardless of nrpages
>> state.
> 
> I'm not understanding this.  I can buy the argument about
> nrexceptional, but why does cleancache require the
> invalidate_inode_pages2_range) call even when ->nrpages is zero?
> 
> I *assume* it's because invalidate_inode_pages2_range() calls
> cleancache_invalidate_inode(), yes?  If so, can we please add this to
> the changelog?  If not then please explain further.
> 

Yes, your assumption is correct. I'll fix the changelog.