Re: [PATCH 5/5] xfs: move xfs_attr_use_log_assist out of libxfs

[Dave Chinner <david@fromorbit.com>]

On Mon, May 23, 2022 at 12:12:21PM -0700, Darrick J. Wong wrote:
> On Mon, May 23, 2022 at 01:34:45PM +1000, Dave Chinner wrote:
> > On Sun, May 22, 2022 at 08:28:42AM -0700, Darrick J. Wong wrote:
> > > From: Darrick J. Wong <djwong@kernel.org>
> > > 
> > > libxfs itself should never be messing with whether or not to enable
> > > logging for extended attribute updates -- this decision should be made
> > > on a case-by-case basis by libxfs callers.  Move the code that actually
> > > enables the log features to xfs_xattr.c, and adjust the callers.
> > > 
> > > This removes an awkward coupling point between libxfs and what would be
> > > libxlog, if the XFS log were actually its own library.  Furthermore, it
> > > makes bulk attribute updates and inode security initialization a tiny
> > > bit more efficient, since they now avoid cycling the log feature between
> > > every single xattr.
> > > 
> > > Signed-off-by: Darrick J. Wong <djwong@kernel.org>
> > > ---
> > >  fs/xfs/libxfs/xfs_attr.c |   12 +-------
> > >  fs/xfs/xfs_acl.c         |   10 +++++++
> > >  fs/xfs/xfs_ioctl.c       |   22 +++++++++++++---
> > >  fs/xfs/xfs_ioctl.h       |    2 +
> > >  fs/xfs/xfs_ioctl32.c     |    4 ++-
> > >  fs/xfs/xfs_iops.c        |   25 ++++++++++++++----
> > >  fs/xfs/xfs_log.c         |   45 --------------------------------
> > >  fs/xfs/xfs_log.h         |    1 -
> > >  fs/xfs/xfs_super.h       |    2 +
> > >  fs/xfs/xfs_xattr.c       |   65 ++++++++++++++++++++++++++++++++++++++++++++++
> > >  10 files changed, 120 insertions(+), 68 deletions(-)
> > 
> > This seems like the wrong way to approach this. I would have defined
> > a wrapper function for xfs_attr_set() to do the log state futzing,
> > not moved it all into callers that don't need (or want) to know
> > anything about how attrs are logged internally....
> 
> I started doing this, and within a few hours realized that I'd set upon
> yet *another* refactoring of xfs_attr_set.  I'm not willing to do that
> so soon after Allison's refactoring, so I'm dropping this patch.

I don't see why this ends up being a problem - xfs_attr_set() is
only called by code in fs/xfs/*.c, so adding a wrapper function
that just does this:

int
xfs_attr_change(
	struct xfs_da_args      *args)
{
	struct xfs_mount	*mp = args->dp->i_mount;

	if (xfs_has_larp(mp)) {
		error = xfs_attr_use_log_assist(mp);
		if (error)
			return error;
	}

	error = xfs_attr_set(args);
	if (xfs_has_larp(mp))
		xlog_drop_incompat_feat(mp->m_log);
	return error;
}

into one of the files in fs/xfs will get this out of libxfs, won't
it?

What am I missing here?

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com