Re: [PATCH 24/25] xfs: scrub realtime bitmap/summary

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

On Mon, Oct 09, 2017 at 01:28:04PM +1100, Dave Chinner wrote:
> On Tue, Oct 03, 2017 at 01:43:21PM -0700, Darrick J. Wong wrote:
> > diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
> > index 154c3dd..d4d9bef 100644
> > --- a/fs/xfs/libxfs/xfs_format.h
> > +++ b/fs/xfs/libxfs/xfs_format.h
> > @@ -315,6 +315,11 @@ static inline bool xfs_sb_good_version(struct xfs_sb *sbp)
> >  	return false;
> >  }
> >  
> > +static inline bool xfs_sb_version_hasrealtime(struct xfs_sb *sbp)
> > +{
> > +	return sbp->sb_rblocks > 0;
> > +}
> 
> How much can we rely on that? do we allow a fs to mount with that
> being > 0 but no rtdev= mount option?
> 
> > +/* Set us up with the realtime metadata locked. */
> > +int
> > +xfs_scrub_setup_rt(
> > +	struct xfs_scrub_context	*sc,
> > +	struct xfs_inode		*ip)
> > +{
> > +	struct xfs_mount		*mp = sc->mp;
> > +	int				lockmode;
> > +	int				error = 0;
> > +
> > +	if (sc->sm->sm_agno || sc->sm->sm_ino || sc->sm->sm_gen)
> > +		return -EINVAL;
> 
> I've forgotten what this means already :/

(I fixed all of these the first time you complained. :))

> > +	error = xfs_scrub_setup_fs(sc, ip);
> > +	if (error)
> > +		return error;
> > +
> > +	lockmode = XFS_ILOCK_EXCL | XFS_ILOCK_RTBITMAP;
> > +	xfs_ilock(mp->m_rbmip, lockmode);
> > +	xfs_trans_ijoin(sc->tp, mp->m_rbmip, lockmode);
> 
> Ok, so why do we join this inode to the transaction and not use
> the sc->ilock_flags field to track how we've locked it?

I don't know why.

It might just be a forgotten leftover from when I started tracking
inodes in the scrub context.

> > +
> > +	return 0;
> > +}
> > +
> > +/* Realtime bitmap. */
> > +
> > +/* Scrub a free extent record from the realtime bitmap. */
> > +STATIC int
> > +xfs_scrub_rtbitmap_helper(
> > +	struct xfs_trans		*tp,
> > +	struct xfs_rtalloc_rec		*rec,
> > +	void				*priv)
> > +{
> > +	return 0;
> > +}
> 
> Check the extent record returned is within the range of the rtdev
> address space?

I added:

if (rec->ar_startblock + rec->ar_blockcount <= rec->ar_startblock ||
    !xfs_verify_rtbno_ptr(sc->mp, rec->ar_startblock) ||
    !xfs_verify_rtbno_ptr(sc->mp, rec->ar_startblock +
		rec->ar_blockcount - 1))
	xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK, 0);

...back when I was reworking the scrub patches to add verify_agbno_ptr and
declutter the bnobt scrubbers.

> > +
> > +/* Scrub the realtime bitmap. */
> > +int
> > +xfs_scrub_rtbitmap(
> > +	struct xfs_scrub_context	*sc)
> > +{
> > +	int				error;
> > +
> > +	error = xfs_rtalloc_query_all(sc->tp, xfs_scrub_rtbitmap_helper, NULL);
> > +	if (!xfs_scrub_fblock_op_ok(sc, XFS_DATA_FORK, 0, &error))
> > +		goto out;
> > +
> > +out:
> > +	return error;
> > +}
> > +
> > +/* Scrub the realtime summary. */
> > +int
> > +xfs_scrub_rtsummary(
> > +	struct xfs_scrub_context	*sc)
> > +{
> > +	/* XXX: implement this some day */
> > +	return -ENOENT;
> > +}
> 
> Alright, this is all just a stub that doesn't really do any real
> scrubbing yet. I guess it's better that nothing in that it walks
> the rtbitmap....
> 
> > --- a/fs/xfs/scrub/scrub.c
> > +++ b/fs/xfs/scrub/scrub.c
> > @@ -241,6 +241,21 @@ static const struct xfs_scrub_meta_ops meta_scrub_ops[] = {
> >  		.setup	= xfs_scrub_setup_parent,
> >  		.scrub	= xfs_scrub_parent,
> >  	},
> > +#ifdef CONFIG_XFS_RT
> > +	{ /* realtime bitmap */
> > +		.setup	= xfs_scrub_setup_rt,
> > +		.scrub	= xfs_scrub_rtbitmap,
> > +		.has	= xfs_sb_version_hasrealtime,
> > +	},
> > +	{ /* realtime summary */
> > +		.setup	= xfs_scrub_setup_rt,
> > +		.scrub	= xfs_scrub_rtsummary,
> > +		.has	= xfs_sb_version_hasrealtime,
> > +	},
> > +#else
> > +	{ NULL },
> > +	{ NULL },
> > +#endif
> 
> I think I'd prefer that you supply stub functions when
> CONFIG_XFS_RT=n so this table doesn't require ifdefs.

Ok.

--D

> 
> Cheers,
> 
> Dave.
> -- 
> Dave Chinner
> david@fromorbit.com
> --
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