Re: [PATCH V8 08/11] fs: Define I_DONTCACNE in VFS layer

From: Ira Weiny <ira.weiny@intel.com>
To: Jan Kara <jack@suse.cz>
Cc: linux-kernel@vger.kernel.org,
	"Darrick J. Wong" <darrick.wong@oracle.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Dave Chinner <david@fromorbit.com>,
	Christoph Hellwig <hch@lst.de>,
	"Theodore Y. Ts'o" <tytso@mit.edu>,
	Jeff Moyer <jmoyer@redhat.com>,
	linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org,
	linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH V8 08/11] fs: Define I_DONTCACNE in VFS layer
Date: Wed, 15 Apr 2020 21:28:10 -0700	[thread overview]
Message-ID: <20200416042810.GG2309605@iweiny-DESK2.sc.intel.com> (raw)
In-Reply-To: <20200415085216.GE501@quack2.suse.cz>

On Wed, Apr 15, 2020 at 10:52:16AM +0200, Jan Kara wrote:
> There's a typo in the subject - I_DONTCACNE.
> 
> On Tue 14-04-20 23:45:20, ira.weiny@intel.com wrote:
> > From: Ira Weiny <ira.weiny@intel.com>
> > 
> > DAX effective mode changes (setting of S_DAX) require inode eviction.
> > 
> > Define a flag which can be set to inform the VFS layer that inodes
> > should not be cached.  This will expedite the eviction of those nodes
> > requiring reload.
> > 
> > Signed-off-by: Ira Weiny <ira.weiny@intel.com>
> > ---
> >  include/linux/fs.h | 6 +++++-
> >  1 file changed, 5 insertions(+), 1 deletion(-)
> > 
> > diff --git a/include/linux/fs.h b/include/linux/fs.h
> > index a818ced22961..e2db71d150c3 100644
> > --- a/include/linux/fs.h
> > +++ b/include/linux/fs.h
> > @@ -2151,6 +2151,8 @@ static inline void kiocb_clone(struct kiocb *kiocb, struct kiocb *kiocb_src,
> >   *
> >   * I_CREATING		New object's inode in the middle of setting up.
> >   *
> > + * I_DONTCACHE		Do not cache the inode
> > + *
> 
> Maybe, I'd be more specific here and write: "Evict inode as soon as it is
> not used anymore"?

Thanks!  done

> 
> Otherwise the patch looks good to me so feel free to add:
> 
> Reviewed-by: Jan Kara <jack@suse.cz>
> 
> Also it would be good to CC Al Viro on this one (and the dentry flag) I
> guess.

Thanks I'll add him on those,

Thanks,
Ira

> 
> 								Honza
> 
> >   * Q: What is the difference between I_WILL_FREE and I_FREEING?
> >   */
> >  #define I_DIRTY_SYNC		(1 << 0)
> > @@ -2173,6 +2175,7 @@ static inline void kiocb_clone(struct kiocb *kiocb, struct kiocb *kiocb_src,
> >  #define I_WB_SWITCH		(1 << 13)
> >  #define I_OVL_INUSE		(1 << 14)
> >  #define I_CREATING		(1 << 15)
> > +#define I_DONTCACHE		(1 << 16)
> >  
> >  #define I_DIRTY_INODE (I_DIRTY_SYNC | I_DIRTY_DATASYNC)
> >  #define I_DIRTY (I_DIRTY_INODE | I_DIRTY_PAGES)
> > @@ -3042,7 +3045,8 @@ extern int inode_needs_sync(struct inode *inode);
> >  extern int generic_delete_inode(struct inode *inode);
> >  static inline int generic_drop_inode(struct inode *inode)
> >  {
> > -	return !inode->i_nlink || inode_unhashed(inode);
> > +	return !inode->i_nlink || inode_unhashed(inode) ||
> > +		(inode->i_state & I_DONTCACHE);
> >  }
> >  
> >  extern struct inode *ilookup5_nowait(struct super_block *sb,
> > -- 
> > 2.25.1
> > 
> -- 
> Jan Kara <jack@suse.com>
> SUSE Labs, CR