Re: [PATCH 1/6] xfs: use XFS_IFORK_BOFF xchk_bmap_check_rmaps

[Brian Foster <bfoster@redhat.com>]

On Mon, May 11, 2020 at 05:10:04PM +0530, Chandan Babu R wrote:
> On Sunday 10 May 2020 12:53:59 PM IST Christoph Hellwig wrote:
> > XFS_IFORK_Q is to be used in boolean context, not for a size.  This
> > doesn't make a difference in practice as size is only checked for
> > 0, but this keeps the logic sane.
> >
> 
> Wouldn't XFS_IFORK_ASIZE() be a better fit since it gives the space used by the
> attr fork inside an inode's literal area?
> 

I had the same thought. It's not clear to me what size is really
supposed to be between the file size for a data fork and fork offset for
the attr fork. I was also wondering if this should use
XFS_IFORK_DSIZE(), but that won't be conditional based on population of
the fork. At the same time, I don't think i_size != 0 necessarily
correlates with the existence of blocks. The file could be completely
sparse or could have any number of post-eof preallocated extents.

Brian

> > Signed-off-by: Christoph Hellwig <hch@lst.de>
> > ---
> >  fs/xfs/scrub/bmap.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/fs/xfs/scrub/bmap.c b/fs/xfs/scrub/bmap.c
> > index add8598eacd5d..283424d6d2bb6 100644
> > --- a/fs/xfs/scrub/bmap.c
> > +++ b/fs/xfs/scrub/bmap.c
> > @@ -591,7 +591,7 @@ xchk_bmap_check_rmaps(
> >  		size = i_size_read(VFS_I(sc->ip));
> >  		break;
> >  	case XFS_ATTR_FORK:
> > -		size = XFS_IFORK_Q(sc->ip);
> > +		size = XFS_IFORK_BOFF(sc->ip);
> >  		break;
> >  	default:
> >  		size = 0;
> > 
> 
> 
> -- 
> chandan
> 
> 
>