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

[Andrew Morton]

On Fri, 14 Apr 2017 17:07:50 +0300 Andrey Ryabinin <aryabinin at virtuozzo.com> 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.