Re: [PATCH 06/11] xfs: quota scrub should use bmapbtd scrubber

[Brian Foster <bfoster@redhat.com>]

On Tue, Apr 17, 2018 at 07:40:14PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> Replace the quota scrubber's open-coded data fork scrubber with a
> redirected call to the bmapbtd scrubber.  This strengthens the quota
> scrub to include all the cross-referencing that it does.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
>  fs/xfs/scrub/quota.c |   95 ++++++++++++++++++++++++++++----------------------
>  1 file changed, 54 insertions(+), 41 deletions(-)
> 
> 
> diff --git a/fs/xfs/scrub/quota.c b/fs/xfs/scrub/quota.c
> index 1068a91..67f94c4 100644
> --- a/fs/xfs/scrub/quota.c
> +++ b/fs/xfs/scrub/quota.c
> @@ -207,65 +207,78 @@ xfs_scrub_quota_item(
>  	return 0;
>  }
>  
> -/* Scrub all of a quota type's items. */
> -int
> -xfs_scrub_quota(
> +/* Check the quota's data fork. */
> +STATIC int
> +xfs_scrub_quota_data_fork(
>  	struct xfs_scrub_context	*sc)
>  {
>  	struct xfs_bmbt_irec		irec = { 0 };
> -	struct xfs_scrub_quota_info	sqi;
> -	struct xfs_mount		*mp = sc->mp;
> -	struct xfs_quotainfo		*qi = mp->m_quotainfo;
> +	struct xfs_iext_cursor		icur;
> +	struct xfs_scrub_metadata	fake_sm;
> +	struct xfs_scrub_metadata	*real_sm = sc->sm;
> +	struct xfs_quotainfo		*qi = sc->mp->m_quotainfo;
> +	struct xfs_ifork		*ifp;
>  	xfs_fileoff_t			max_dqid_off;
> -	xfs_fileoff_t			off = 0;
> -	uint				dqtype;
> -	int				nimaps;
>  	int				error = 0;
>  
> -	dqtype = xfs_scrub_quota_to_dqtype(sc);
> -
> -	/* Look for problem extents. */
> +	/* Quotas don't live on the rt device. */
>  	if (sc->ip->i_d.di_flags & XFS_DIFLAG_REALTIME) {
>  		xfs_scrub_ino_set_corrupt(sc, sc->ip->i_ino);
> -		goto out;
> +		return 0;
>  	}
> +
> +	/* Invoke the data fork scrubber. */
> +	memcpy(&fake_sm, real_sm, sizeof(fake_sm));
> +	fake_sm.sm_type = XFS_SCRUB_TYPE_BMBTD;
> +	fake_sm.sm_flags &= ~XFS_SCRUB_FLAGS_OUT;
> +	sc->sm = &fake_sm;
> +	error = xfs_scrub_bmap_data(sc);
> +	sc->sm = real_sm;

Is the sm swap out of caution or is there really some conflict here?
AFAICT sm_type is only used in the setup handler (and tracepoints).
With respect to sm_flags, what's the difference between the above and
just passing in the original sm without stripping FLAGS_OUT (whatever it
is, might be useful to note in the comment)?

> +	if (error)
> +		return error;
> +	sc->sm->sm_flags |= (fake_sm.sm_flags & XFS_SCRUB_FLAGS_OUT);
> +	if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
> +		return error;
> +
> +	/* Check for data fork problems that apply only to quota files. */
>  	max_dqid_off = ((xfs_dqid_t)-1) / qi->qi_dqperchunk;
> -	while (1) {
> +	ifp = XFS_IFORK_PTR(sc->ip, XFS_DATA_FORK);
> +	for_each_xfs_iext(ifp, &icur, &irec) {
>  		if (xfs_scrub_should_terminate(sc, &error))
>  			break;
> -
> -		off = irec.br_startoff + irec.br_blockcount;
> -		nimaps = 1;
> -		error = xfs_bmapi_read(sc->ip, off, -1, &irec, &nimaps,
> -				XFS_BMAPI_ENTIRE);
> -		if (!xfs_scrub_fblock_process_error(sc, XFS_DATA_FORK, off,
> -				&error))
> -			goto out;
> -		if (!nimaps)
> -			break;
> -		if (irec.br_startblock == HOLESTARTBLOCK)
> -			continue;
> -
> -		/* Check the extent record doesn't point to crap. */
> -		if (irec.br_startblock + irec.br_blockcount <=
> -		    irec.br_startblock)
> -			xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK,
> -					irec.br_startoff);
> -		if (!xfs_verify_fsbno(mp, irec.br_startblock) ||
> -		    !xfs_verify_fsbno(mp, irec.br_startblock +
> -					irec.br_blockcount - 1))
> -			xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK,
> -					irec.br_startoff);
> -
>  		/*
> -		 * Unwritten extents or blocks mapped above the highest
> +		 * delalloc extents or blocks mapped above the highest
>  		 * quota id shouldn't happen.
>  		 */
>  		if (isnullstartblock(irec.br_startblock) ||
>  		    irec.br_startoff > max_dqid_off ||
> -		    irec.br_startoff + irec.br_blockcount > max_dqid_off + 1)
> -			xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK, off);
> +		    irec.br_startoff + irec.br_blockcount > max_dqid_off + 1) {

Not introduced by this patch, but what's with the +1 to max_dqid_off
here?

Brian

> +			xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK,
> +					irec.br_startoff);
> +			break;
> +		}
>  	}
> +
> +	return error;
> +}
> +
> +/* Scrub all of a quota type's items. */
> +int
> +xfs_scrub_quota(
> +	struct xfs_scrub_context	*sc)
> +{
> +	struct xfs_scrub_quota_info	sqi;
> +	struct xfs_mount		*mp = sc->mp;
> +	struct xfs_quotainfo		*qi = mp->m_quotainfo;
> +	uint				dqtype;
> +	int				error = 0;
> +
> +	dqtype = xfs_scrub_quota_to_dqtype(sc);
> +
> +	/* Look for problem extents. */
> +	error = xfs_scrub_quota_data_fork(sc);
> +	if (error)
> +		goto out;
>  	if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
>  		goto out;
>  
> 
> --
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