Re: [PATCH V9 09/11] fs: Introduce DCACHE_DONTCACHE

[Al Viro]

On Tue, Apr 21, 2020 at 01:25:19PM -0700, Darrick J. Wong wrote:

> > DCACHE_DONTCACHE indicates a dentry should not be cached on final
> > dput().
> > 
> > Also add a helper function to mark DCACHE_DONTCACHE on all dentries
> > pointing to a specific inode when that inode is being set I_DONTCACHE.
> > 
> > This facilitates dropping dentry references to inodes sooner which
> > require eviction to swap S_DAX mode.

Explain, please.  Questions:

1) does that ever happen to directories?
2) how much trouble do we get if such inode is *NOT* evicted for, say, several
days?