On Tue, Jan 09, 2018 at 10:51:25AM +1100, Dave Chinner wrote:
> On Fri, Dec 22, 2017 at 04:44:18PM -0800, Darrick J. Wong wrote:
> > From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> >
> > When we're scrubbing various btrees, cross-reference the records with
> > the bnobt to ensure that we don't also think the space is free.
> >
> > Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> > ---
> > fs/xfs/scrub/agheader.c | 84 +++++++++++++++++++++++++++++++++++++++++++++++
> > fs/xfs/scrub/alloc.c | 19 +++++++++++
> > fs/xfs/scrub/bmap.c | 21 +++++++++++-
> > fs/xfs/scrub/btree.c | 12 +++++++
> > fs/xfs/scrub/ialloc.c | 1 +
> > fs/xfs/scrub/inode.c | 15 ++++++++
> > fs/xfs/scrub/refcount.c | 1 +
> > fs/xfs/scrub/rmap.c | 4 ++
> > fs/xfs/scrub/scrub.h | 5 +++
> > 9 files changed, 161 insertions(+), 1 deletion(-)
> >
> >
> > diff --git a/fs/xfs/scrub/agheader.c b/fs/xfs/scrub/agheader.c
> > index 5be9059..3bb0f96 100644
> > --- a/fs/xfs/scrub/agheader.c
> > +++ b/fs/xfs/scrub/agheader.c
> > @@ -107,6 +107,20 @@ xfs_scrub_superblock_xref(
> > struct xfs_scrub_context *sc,
> > struct xfs_buf *bp)
> > {
> > + struct xfs_mount *mp = sc->mp;
> > + xfs_agnumber_t agno = sc->sm->sm_agno;
> > + xfs_agblock_t bno;
> > + int error;
> > +
> > + bno = XFS_SB_BLOCK(mp);
>
> agbno
Fixed (and all the others).
> > +
> > + error = xfs_scrub_ag_init(sc, agno, &sc->sa);
> > + if (!xfs_scrub_xref_process_error(sc, agno, bno, &error))
> > + return;
> > +
> > + xfs_scrub_xref_not_free(sc, &sc->sa.bno_cur, bno, 1);
>
> "xref_not_free". That doesn't tell me what it's actually checking
> is not free, or what it's checking against. Seeing as we're checking
> these all against the bnobt, wouldn't something like this be more
> obvious:
>
> xfs_scrub_is_used_space(sc, agbno, 1);
I've been trying to keep "xref" in the name of the functions that help
us do cross-referencing, but you're right that the **pcur parameter can
drop out. I'll ... do that. :)
> > + /* scrub teardown will take care of sc->sa for us */
> > }
> >
> > /*
> > @@ -407,11 +421,51 @@ xfs_scrub_superblock(
> >
> > /* AGF */
> >
> > +/* Tally freespace record lengths. */
> > +STATIC int
> > +xfs_scrub_agf_record_bno_lengths(
> > + struct xfs_btree_cur *cur,
> > + struct xfs_alloc_rec_incore *rec,
> > + void *priv)
> > +{
> > + xfs_extlen_t *blocks = priv;
> > +
> > + (*blocks) += rec->ar_blockcount;
> > + return 0;
> > +}
> > +
> > /* Cross-reference with the other btrees. */
> > STATIC void
> > xfs_scrub_agf_xref(
> > struct xfs_scrub_context *sc)
> > {
> > + struct xfs_mount *mp = sc->mp;
> > + struct xfs_agf *agf = XFS_BUF_TO_AGF(sc->sa.agf_bp);
> > + struct xfs_btree_cur **pcur;
> > + xfs_agblock_t bno;
> > + xfs_extlen_t blocks;
> > + int error;
> > +
> > + bno = XFS_AGF_BLOCK(mp);
>
> agbno. (and for all the others)
>
> > +
> > + error = xfs_scrub_ag_btcur_init(sc, &sc->sa);
> > + if (error)
> > + return;
> > +
> > + xfs_scrub_xref_not_free(sc, &sc->sa.bno_cur, bno, 1);
> > +
> > + /* Check agf_freeblks */
> > + pcur = &sc->sa.bno_cur;
> > + if (*pcur) {
> > + blocks = 0;
> > + error = xfs_alloc_query_all(*pcur,
> > + xfs_scrub_agf_record_bno_lengths, &blocks);
> > + if (xfs_scrub_should_xref(sc, &error, pcur) &&
> > + blocks != be32_to_cpu(agf->agf_freeblks))
> > + xfs_scrub_block_xref_set_corrupt(sc, sc->sa.agf_bp);
> > + }
>
> I have no idea what xfs_scrub_should_xref() means in this context.
> We're doing a xref scrub, so why are we asking if we should be
> running a xref?
Given that we tried to retrieve some data from some other data
structure, the function xfs_scrub_should_xref decides if we should
actually bother with the comparison checks? In other words, if the
xfs_alloc_query_all returned an error code then we need to delete *pcur
and we can skip the "blocks != be32..." check since it makes no sense.
How about xfs_scrub_should_check_xref?
>
>
> > diff --git a/fs/xfs/scrub/alloc.c b/fs/xfs/scrub/alloc.c
> > index 0d95b84..3d6f8cc 100644
> > --- a/fs/xfs/scrub/alloc.c
> > +++ b/fs/xfs/scrub/alloc.c
> > @@ -114,3 +114,22 @@ xfs_scrub_cntbt(
> > {
> > return xfs_scrub_allocbt(sc, XFS_BTNUM_CNT);
> > }
> > +
> > +/* xref check that the extent is not free */
> > +void
> > +xfs_scrub_xref_not_free(
> > + struct xfs_scrub_context *sc,
> > + struct xfs_btree_cur **pcur,
> > + xfs_agblock_t bno,
> > + xfs_extlen_t len)
> > +{
> > + bool is_freesp;
> > + int error;
> > +
> > + if (!(*pcur))
> > + return;
> > +
> > + error = xfs_alloc_has_record(*pcur, bno, len, &is_freesp);
> > + if (xfs_scrub_should_xref(sc, &error, pcur) && is_freesp)
> > + xfs_scrub_btree_xref_set_corrupt(sc, *pcur, 0);
> > +}
>
> Again, "should_xref" doesn't actually tell me anything about what
> this function is doing...
>
> > @@ -117,6 +117,25 @@ xfs_scrub_bmap_extent_xref(
> > struct xfs_btree_cur *cur,
> > struct xfs_bmbt_irec *irec)
> > {
> > + struct xfs_scrub_ag sa = { 0 };
> > + struct xfs_mount *mp = info->sc->mp;
> > + xfs_agnumber_t agno;
> > + xfs_agblock_t agbno;
> > + xfs_extlen_t len;
> > + int error;
> > +
> > + agno = XFS_FSB_TO_AGNO(mp, irec->br_startblock);
> > + agbno = XFS_FSB_TO_AGBNO(mp, irec->br_startblock);
> > + len = irec->br_blockcount;
> > +
> > + error = xfs_scrub_ag_init(info->sc, agno, &sa);
> > + if (!xfs_scrub_fblock_process_error(info->sc, info->whichfork,
> > + irec->br_startoff, &error))
> > + return;
> > +
> > + xfs_scrub_xref_not_free(info->sc, &sa.bno_cur, agbno, len);
> > +
> > + xfs_scrub_ag_free(info->sc, &sa);
>
> Why do we use an on-stack struct xfs_scrub_ag here, and not the one
> embedded into the scrub context like all the other functions in this
> patch?
I think this is an archaic side effect of a previous version of scrub
when the xfs_scrub_ag wasn't embedded in the scrub context. :/
IOWs, there's no reason, I'll go fix it (and the others).
--D
> > }
> >
> > /* Scrub a single extent record. */
> > diff --git a/fs/xfs/scrub/btree.c b/fs/xfs/scrub/btree.c
> > index 9151499..ae58fcc 100644
> > --- a/fs/xfs/scrub/btree.c
> > +++ b/fs/xfs/scrub/btree.c
> > @@ -381,9 +381,12 @@ xfs_scrub_btree_check_block_owner(
> > struct xfs_scrub_ag sa = { 0 };
> > struct xfs_scrub_ag *psa;
> > xfs_agnumber_t agno;
> > + xfs_agblock_t bno;
> > + bool is_freesp;
> > int error = 0;
> >
> > agno = xfs_daddr_to_agno(bs->cur->bc_mp, daddr);
> > + bno = xfs_daddr_to_agbno(bs->cur->bc_mp, daddr);
>
> agbno.
>
> > @@ -584,6 +584,21 @@ xfs_scrub_inode_xref(
> > xfs_ino_t ino,
> > struct xfs_dinode *dip)
> > {
> > + struct xfs_scrub_ag sa = { 0 };
> > + xfs_agnumber_t agno;
> > + xfs_agblock_t agbno;
> > + int error;
> > +
> > + agno = XFS_INO_TO_AGNO(sc->mp, ino);
> > + agbno = XFS_INO_TO_AGBNO(sc->mp, ino);
> > +
> > + error = xfs_scrub_ag_init(sc, agno, &sa);
> > + if (!xfs_scrub_xref_process_error(sc, agno, agbno, &error))
> > + return;
> > +
> > + xfs_scrub_xref_not_free(sc, &sa.bno_cur, agbno, 1);
> > +
> > + xfs_scrub_ag_free(sc, &sa);
>
> Same question here - on-stack vs embedded....
>
> Cheers,
>
> Dave.
> --
> Dave Chinner
> david@xxxxxxxxxxxxx
> --
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