Re: [PATCH V9 08/11] fs: Lift XFS_IDONTCACNE to the VFS layer

From: Ira Weiny <ira.weiny@intel.com>
To: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org,
	Al Viro <viro@zeniv.linux.org.uk>, Jan Kara <jack@suse.cz>,
	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-fsdevel@vger.kernel.org
Subject: Re: [PATCH V9 08/11] fs: Lift XFS_IDONTCACNE to the VFS layer
Date: Tue, 21 Apr 2020 14:12:37 -0700	[thread overview]
Message-ID: <20200421211237.GB3372712@iweiny-DESK2.sc.intel.com> (raw)
In-Reply-To: <20200421202314.GB6742@magnolia>

On Tue, Apr 21, 2020 at 01:23:14PM -0700, Darrick J. Wong wrote:
> > Subject: [PATCH V9 08/11] fs: Lift XFS_IDONTCACNE to the VFS layer
> 
> This still has a misspelling in the subject line.

Sorry...  My reliance on spell check is thwarted by macros again!  ;-)

> 
> On Tue, Apr 21, 2020 at 12:17:50PM -0700, ira.weiny@intel.com wrote:
> > From: Ira Weiny <ira.weiny@intel.com>
> > 
> > DAX effective mode (S_DAX) changes requires inode eviction.
> > 
> > XFS has an advisory flag (XFS_IDONTCACHE) to prevent caching of the
> > inode if no other additional references are taken.  We lift this flag to
> > the VFS layer and change the behavior slightly by allowing the flag to
> > remain even if multiple references are taken.
> > 
> > This will expedite the eviction of inodes to change S_DAX.
> > 
> > Cc: Al Viro <viro@zeniv.linux.org.uk>
> > Signed-off-by: Ira Weiny <ira.weiny@intel.com>
> > 
> > ---
> > Changes from V8:
> > 	Remove XFS_IDONTCACHE
> > ---
> >  fs/xfs/xfs_icache.c | 4 ++--
> >  fs/xfs/xfs_inode.h  | 2 +-
> >  fs/xfs/xfs_super.c  | 2 +-
> >  include/linux/fs.h  | 6 +++++-
> >  4 files changed, 9 insertions(+), 5 deletions(-)
> > 
> > diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
> > index 17a0b86fe701..de76f7f60695 100644
> > --- a/fs/xfs/xfs_icache.c
> > +++ b/fs/xfs/xfs_icache.c
> > @@ -477,7 +477,7 @@ xfs_iget_cache_hit(
> >  		xfs_ilock(ip, lock_flags);
> >  
> >  	if (!(flags & XFS_IGET_INCORE))
> > -		xfs_iflags_clear(ip, XFS_ISTALE | XFS_IDONTCACHE);
> > +		xfs_iflags_clear(ip, XFS_ISTALE);
> >  	XFS_STATS_INC(mp, xs_ig_found);
> >  
> >  	return 0;
> > @@ -559,7 +559,7 @@ xfs_iget_cache_miss(
> >  	 */
> >  	iflags = XFS_INEW;
> >  	if (flags & XFS_IGET_DONTCACHE)
> > -		iflags |= XFS_IDONTCACHE;
> > +		VFS_I(ip)->i_state |= I_DONTCACHE;
> >  	ip->i_udquot = NULL;
> >  	ip->i_gdquot = NULL;
> >  	ip->i_pdquot = NULL;
> > diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
> > index 83073c883fbf..52b8ee21a0b1 100644
> > --- a/fs/xfs/xfs_inode.h
> > +++ b/fs/xfs/xfs_inode.h
> > @@ -218,7 +218,7 @@ static inline bool xfs_inode_has_cow_data(struct xfs_inode *ip)
> >  #define XFS_IFLOCK		(1 << __XFS_IFLOCK_BIT)
> >  #define __XFS_IPINNED_BIT	8	 /* wakeup key for zero pin count */
> >  #define XFS_IPINNED		(1 << __XFS_IPINNED_BIT)
> > -#define XFS_IDONTCACHE		(1 << 9) /* don't cache the inode long term */
> > +/* Was XFS_IDONTCACHE 9 */
> >  #define XFS_IEOFBLOCKS		(1 << 10)/* has the preallocblocks tag set */
> 
> These are incore state flags, you can change XFS_IEOFBLOCKS to (1 << 9).

Sounds good changed.

Thanks,
Ira

> 
> --D
> 
> >  /*
> >   * If this unlinked inode is in the middle of recovery, don't let drop_inode
> > diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
> > index 0d0f74786799..2e165e226e15 100644
> > --- a/fs/xfs/xfs_super.c
> > +++ b/fs/xfs/xfs_super.c
> > @@ -742,7 +742,7 @@ xfs_fs_drop_inode(
> >  		return 0;
> >  	}
> >  
> > -	return generic_drop_inode(inode) || (ip->i_flags & XFS_IDONTCACHE);
> > +	return generic_drop_inode(inode);
> >  }
> >  
> >  static void
> > diff --git a/include/linux/fs.h b/include/linux/fs.h
> > index a87cc5845a02..44bd45af760f 100644
> > --- a/include/linux/fs.h
> > +++ b/include/linux/fs.h
> > @@ -2156,6 +2156,8 @@ 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		Evict inode as soon as it is not used anymore.
> > + *
> >   * Q: What is the difference between I_WILL_FREE and I_FREEING?
> >   */
> >  #define I_DIRTY_SYNC		(1 << 0)
> > @@ -2178,6 +2180,7 @@ 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)
> > @@ -3049,7 +3052,8 @@ 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
> > 