Re: [PATCH v2 19/21] xfs: cross-reference refcount btree during scrub

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

On Tue, Jan 16, 2018 at 01:44:47PM +1100, Dave Chinner wrote:
> On Tue, Jan 09, 2018 at 01:25:47PM -0800, Darrick J. Wong wrote:
> > From: Darrick J. Wong <darrick.wong@oracle.com>
> > 
> > During metadata btree scrub, we should cross-reference with the
> > reference counts.
> > 
> > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> > ---
> > v2: streamline scrubber arguments, remove stack allocated objects
> > ---
> 
> ....
> 
> > +/* Make sure the refcount records match this data fork extent. */
> > +STATIC void
> > +xfs_scrub_bmap_xref_refcount_data(
> > +	struct xfs_scrub_bmap_info	*info,
> > +	struct xfs_bmbt_irec		*irec,
> > +	xfs_fsblock_t			bno)
> 
> What's in the irec if it's not the block number of the extent we
> are looking up?
> 
> Actually, I may have just answered that myself: bno is actually
> an agbno, not an fsbno. So that should be:
> 
> 	xfs_agblock_t			agbno)

Er... Yes.  Oops, will fix (all of the agbno).
> 
> > +{
> > +	xfs_agblock_t			fbno;
> > +	xfs_extlen_t			flen;
> > +	int				error;
> > +
> > +	if (!info->sc->sa.refc_cur)
> > +		return;
> > +
> > +	/* If this is shared, the inode flag must be set. */
> > +	error = xfs_refcount_find_shared(info->sc->sa.refc_cur, bno,
> > +			irec->br_blockcount, &fbno, &flen, false);
> > +	if (!xfs_scrub_should_check_xref(info->sc, &error,
> > +			&info->sc->sa.refc_cur))
> > +		return;
> > +
> > +	if (flen != 0 && !xfs_is_reflink_inode(info->sc->ip))
> > +		xfs_scrub_fblock_xref_set_corrupt(info->sc, info->whichfork,
> > +				irec->br_startoff);
> 
> So is the block corrupt or is the inode flags corrupt? What
> determines the object we mark as corrupt/needing fixing here?

Hmm.  The reflink iflag is broken here, because the iflag is only supposed
to represent a shortcut for "might any of the data fork blocks shared?"
Will change to the ino_xref_set_corrupt helper.

--D

> > +/* Make sure the refcount records match this attr fork extent. */
> > +STATIC void
> > +xfs_scrub_bmap_xref_refcount_attr(
> > +	struct xfs_scrub_bmap_info	*info,
> > +	struct xfs_bmbt_irec		*irec,
> > +	xfs_fsblock_t			bno)
> 
> agbno
> 
> > +{
> > +	xfs_agblock_t			fbno;
> > +	xfs_extlen_t			flen;
> > +	int				error;
> > +
> > +	if (!info->sc->sa.refc_cur)
> > +		return;
> > +
> > +	/* No shared attr fork extents */
> > +	error = xfs_refcount_find_shared(info->sc->sa.refc_cur, bno,
> > +			irec->br_blockcount, &fbno, &flen, false);
> > +	if (!xfs_scrub_should_check_xref(info->sc, &error,
> > +			&info->sc->sa.refc_cur))
> > +		return;
> > +
> > +	if (flen != 0)
> > +		xfs_scrub_fblock_xref_set_corrupt(info->sc, info->whichfork,
> > +				irec->br_startoff);
> > +}
> > +
> > +/* Make sure the refcount records match this CoW fork extent. */
> > +STATIC void
> > +xfs_scrub_bmap_xref_refcount_cow(
> > +	struct xfs_scrub_bmap_info	*info,
> > +	struct xfs_bmbt_irec		*irec,
> > +	xfs_fsblock_t			bno)
> 
> agbno
> 
> > +{
> > +	if (!info->sc->sa.refc_cur)
> > +		return;
> > +
> > +	xfs_scrub_xref_has_cow_staging(info->sc, bno, irec->br_blockcount);
> > +}
> > +
> >  /* Cross-reference a single rtdev extent record. */
> >  STATIC void
> >  xfs_scrub_bmap_rt_extent_xref(
> > @@ -243,6 +309,17 @@ xfs_scrub_bmap_extent_xref(
> >  	xfs_scrub_xref_is_used_space(info->sc, agbno, len);
> >  	xfs_scrub_xref_not_inodes(info->sc, agbno, len);
> >  	xfs_scrub_bmap_xref_rmap(info, irec, agbno);
> > +	switch (info->whichfork) {
> > +	case XFS_DATA_FORK:
> > +		xfs_scrub_bmap_xref_refcount_data(info, irec, agbno);
> > +		break;
> > +	case XFS_ATTR_FORK:
> > +		xfs_scrub_bmap_xref_refcount_attr(info, irec, agbno);
> > +		break;
> > +	case XFS_COW_FORK:
> > +		xfs_scrub_bmap_xref_refcount_cow(info, irec, agbno);
> > +		break;
> 
> This is where the agbno comes from :P
> 
> > +	}
> >  
> >  	xfs_scrub_ag_free(info->sc, &info->sc->sa);
> >  }
> > diff --git a/fs/xfs/scrub/ialloc.c b/fs/xfs/scrub/ialloc.c
> > index 30603b4..fb16314 100644
> > --- a/fs/xfs/scrub/ialloc.c
> > +++ b/fs/xfs/scrub/ialloc.c
> > @@ -97,6 +97,7 @@ xfs_scrub_iallocbt_chunk_xref(
> >  
> >  	xfs_rmap_ag_owner(&oinfo, XFS_RMAP_OWN_INODES);
> >  	xfs_scrub_xref_owned_by(sc, agbno, len, &oinfo);
> > +	xfs_scrub_xref_not_shared(sc, agbno, len);
> >  }
> >  
> >  /* Is this chunk worth checking? */
> > diff --git a/fs/xfs/scrub/inode.c b/fs/xfs/scrub/inode.c
> > index fc546f2..f12586c 100644
> > --- a/fs/xfs/scrub/inode.c
> > +++ b/fs/xfs/scrub/inode.c
> > @@ -652,6 +652,7 @@ xfs_scrub_inode_xref(
> >  	xfs_scrub_inode_xref_finobt(sc, ino);
> >  	xfs_rmap_ag_owner(&oinfo, XFS_RMAP_OWN_INODES);
> >  	xfs_scrub_xref_owned_by(sc, agbno, 1, &oinfo);
> > +	xfs_scrub_xref_not_shared(sc, agbno, 1);
> >  
> >  	xfs_scrub_ag_free(sc, &sc->sa);
> >  }
> > diff --git a/fs/xfs/scrub/refcount.c b/fs/xfs/scrub/refcount.c
> > index df18e47..6e5b12a 100644
> > --- a/fs/xfs/scrub/refcount.c
> > +++ b/fs/xfs/scrub/refcount.c
> > @@ -31,6 +31,7 @@
> >  #include "xfs_sb.h"
> >  #include "xfs_alloc.h"
> >  #include "xfs_rmap.h"
> > +#include "xfs_refcount.h"
> >  #include "scrub/xfs_scrub.h"
> >  #include "scrub/scrub.h"
> >  #include "scrub/common.h"
> > @@ -428,3 +429,67 @@ xfs_scrub_refcountbt(
> >  
> >  	return error;
> >  }
> > +
> > +/* xref check that a cow staging extent is marked in the refcountbt. */
> > +void
> > +xfs_scrub_xref_has_cow_staging(
> > +	struct xfs_scrub_context	*sc,
> > +	xfs_agblock_t			bno,
> 
> agbno
> 
> > +	xfs_extlen_t			len)
> > +{
> > +	struct xfs_refcount_irec	rc;
> > +	bool				has_cowflag;
> > +	int				has_refcount;
> > +	int				error;
> .....
> > +/*
> > + * xref check that the extent is not shared.  Only file data blocks
> > + * can have multiple owners.
> > + */
> > +void
> > +xfs_scrub_xref_not_shared(
> > +	struct xfs_scrub_context	*sc,
> > +	xfs_agblock_t			bno,
> 
> agbno
> 
> Cheers,
> 
> Dave.
> -- 
> Dave Chinner
> david@fromorbit.com
> --
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