Re: [PATCH 2/3] xfs: clean up xfs_bui_item_recover iget/trans_alloc/ilock ordering

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Fri, Oct 02, 2020 at 12:27:54PM -0400, Brian Foster wrote:
> On Tue, Sep 29, 2020 at 10:44:00AM -0700, Darrick J. Wong wrote:
> > From: Darrick J. Wong <darrick.wong@oracle.com>
> > 
> > In most places in XFS, we have a specific order in which we gather
> > resources: grab the inode, allocate a transaction, then lock the inode.
> > xfs_bui_item_recover doesn't do it in that order, so fix it to be more
> > consistent.  This also makes the error bailout code a bit less weird.
> > 
> > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> > Reviewed-by: Dave Chinner <dchinner@redhat.com>
> > Reviewed-by: Christoph Hellwig <hch@lst.de>
> > ---
> >  fs/xfs/xfs_bmap_item.c |   42 ++++++++++++++++++++++--------------------
> >  1 file changed, 22 insertions(+), 20 deletions(-)
> > 
> > 
> > diff --git a/fs/xfs/xfs_bmap_item.c b/fs/xfs/xfs_bmap_item.c
> > index c1f2cc3c42cb..1c9cb5a04bb5 100644
> > --- a/fs/xfs/xfs_bmap_item.c
> > +++ b/fs/xfs/xfs_bmap_item.c
> ...
> > @@ -512,18 +513,19 @@ xfs_bui_item_recover(
> >  		xfs_bmap_unmap_extent(tp, ip, &irec);
> >  	}
> >  
> > +	/* Commit transaction, which frees tp. */
> >  	error = xfs_defer_ops_capture_and_commit(tp, capture_list);
> > +	if (error)
> > +		goto err_unlock;
> > +	return 0;
> > +
> > +err_cancel:
> > +	xfs_trans_cancel(tp);
> > +err_unlock:
> >  	xfs_iunlock(ip, XFS_ILOCK_EXCL);
> > +err_rele:
> >  	xfs_irele(ip);
> 
> What happened to the unlock and irele in the non-error path?

xfs_defer_capture_and_consume did that, but see christoph's reply.

--D

> Brian
> 
> >  	return error;
> > -
> > -err_inode:
> > -	xfs_trans_cancel(tp);
> > -	if (ip) {
> > -		xfs_iunlock(ip, XFS_ILOCK_EXCL);
> > -		xfs_irele(ip);
> > -	}
> > -	return error;
> >  }
> >  
> >  STATIC bool
> > 
>