Re: [PATCH v2 10/13] xfs: Unmap blocks according to forcealign

[John Garry]

On 06/07/2024 08:58, Christoph Hellwig wrote:
> > +static xfs_extlen_t
> > +xfs_bunmapi_align(
> > +	struct xfs_inode	*ip,
> > +	xfs_fsblock_t		bno)
> > +{
> > +	struct xfs_mount	*mp = ip->i_mount;
> > +	xfs_agblock_t		agbno;
> > +
> > +	if (xfs_inode_has_forcealign(ip)) {
> > +		if (is_power_of_2(ip->i_extsize))
> > +			return bno & (ip->i_extsize - 1);
> > +
> > +		agbno = XFS_FSB_TO_AGBNO(mp, bno);
> > +		return agbno % ip->i_extsize;
> > +	}
> > +	ASSERT(XFS_IS_REALTIME_INODE(ip));
> > +	return xfs_rtb_to_rtxoff(ip->i_mount, bno);
>
> This helper isn't really bunmapi sepcific, is it?

Right, it is not really. Apart from the ASSERT to ensure that we are not 
calling from a stray context.

> > @@ -5425,6 +5444,7 @@ __xfs_bunmapi(
> >   	struct xfs_bmbt_irec	got;		/* current extent record */
> >   	struct xfs_ifork	*ifp;		/* inode fork pointer */
> >   	int			isrt;		/* freeing in rt area */
> > +	int			isforcealign;	/* freeing for inode with forcealign */
>
> This is really a bool.  And while it matches the code around it the
> code feels a bit too verbose..

I can change both to a bool - would that be better?

Using isfa (instead of isforcealign) might be interpreted as something 
else :)

> > +		if ((!isrt && !isforcealign) || (flags & XFS_BMAPI_REMAP))
> >   			goto delete;
> >   
> > -		mod = xfs_rtb_to_rtxoff(mp,
> > -				del.br_startblock + del.br_blockcount);
> > +		mod = xfs_bunmapi_align(ip, del.br_startblock + del.br_blockcount);
>
> Overly long line.

noted

> We've been long wanting to split the whole align / convert unwritten /
> etc code into a helper outside the main bumapi flow.  And when adding
> new logic to it this might indeed be a good time.

ok, I'll see if can come up with something

> > +			if (isforcealign) {
> > +				off = ip->i_extsize - mod;
> > +			} else {
> > +				ASSERT(isrt);
> > +				off = mp->m_sb.sb_rextsize - mod;
> > +			}
>
> And we'll really need proper helpers so that we don't have to
> open code the i_extsize vs sb_rextsize logic all over.

sure

>