Re: [RFC PATCH 2/2] xfs_export_operations.commit_metadata

Dave Chinner
2010-02-10T21:29:14Z

On Wed, Feb 10, 2010 at 02:15:27PM -0600, bpm@sgi.com wrote:
> Howdy,
>
> On Wed, Feb 10, 2010 at 04:07:50AM -0500, Christoph Hellwig wrote:
> > On Tue, Feb 09, 2010 at 06:33:37PM -0600, Ben Myers wrote:
> > > hopefully
> > > the XFS gurus can continue to provide guidance.
> >
> > Ccing the xfs list would help with that :)
>
> I'll cross-post the next rev. ;)
>
> > > + if (xfs_ipincount(c_xip)) {
> > > + /*
> > > + * AFAICS the child is always modified after the parent
> > > + * in nfsd so should always have a larger lsn.
> > > + */
> > > + if (c_xip->i_itemp->ili_last_lsn > force_lsn) {
> > > + force_lsn = c_xip->i_itemp->ili_last_lsn;
> > > + } else {
> > > + force_lsn = 0; /* whole thing */
> > > + }
> >
> > I wouldn't rely on that and always take the larger one.
>
> I am concerned that ili_last_lsn will roll over at some point. I
> haven't figured out how to detect that yet.

XFS_LSN_CMP() should be used for LSN comparisons - it handles
rollover corectly.

> > Now with the simplification of always having a non-zero first argument
> > suggested in the previous mail this might be simplified down to:
> >
> > STATIC int
> > xfs_fs_nfs_commit_metadata(
> > struct dentry *parent,
> > struct dentry *child)
> > {
> > struct xfs_inode *dp = XFS_I(parent->d_inode);
> > struct xfs_inode *ip = NULL;
> > struct xfs_mount *mp = dp->i_mount;
> > xfs_lsn_t force_lsn = 0;
> > int error = 0;
> >
> > if (child) {
> > ip = XFS_I(child->d_inode);
> > xfs_lock_two_inodes(dp, ip, XFS_ILOCK_SHARED);
> > } else {
> > xfs_ilock(dp, XFS_ILOCK_SHARED);
> > }
> >
> > if (xfs_ipincount(dp))
> > force_lsn = dp->i_itemp->ili_last_lsn;
> > if (ip && xfs_ipincount(ip))
> > force_lsn = max(force_lsn, ip->i_itemp->ili_last_lsn);

So this should be:

if (XFS_LSN_CMP(force_lsn, ip->i_itemp->ili_last_lsn) < 0)
force_lsn = ip->i_itemp->ili_last_lsn;

Cheers,

Dave.
--
Dave Chinner
david@fromorbit.com

_______________________________________________
xfs mailing list
xfs@oss.sgi.com