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

[Dave Chinner <david@fromorbit.com>]

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)

> +{
> +	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?

> +/* 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