On Thu, Oct 17, 2019 at 08:55:37AM -0400, Brian Foster wrote:
> On Wed, Oct 09, 2019 at 09:48:53AM -0700, Darrick J. Wong wrote:
> > From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> >
> > Use deferred frees (EFIs) to reap the blocks of a btree that we just
> > replaced. This helps us to shrink the window in which those old blocks
> > could be lost due to a system crash, though we try to flush the EFIs
> > every few hundred blocks so that we don't also overflow the transaction
> > reservations during and after we commit the new btree.
> >
> > Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> > ---
> > fs/xfs/scrub/repair.c | 29 ++++++++++++++++++++++++-----
> > 1 file changed, 24 insertions(+), 5 deletions(-)
> >
> >
> > diff --git a/fs/xfs/scrub/repair.c b/fs/xfs/scrub/repair.c
> > index e21faef6db5a..8349694f985d 100644
> > --- a/fs/xfs/scrub/repair.c
> > +++ b/fs/xfs/scrub/repair.c
> ...
> > @@ -565,14 +568,24 @@ xrep_reap_block(
> > xrep_reap_invalidate_block(sc, fsbno);
> > error = xrep_put_freelist(sc, agbno);
> > } else {
> > + /*
> > + * Use deferred frees to get rid of the old btree blocks to try
> > + * to minimize the window in which we could crash and lose the
> > + * old blocks. However, we still need to roll the transaction
> > + * every 100 or so EFIs so that we don't exceed the log
> > + * reservation.
> > + */
> > xrep_reap_invalidate_block(sc, fsbno);
> > - error = xfs_free_extent(sc->tp, fsbno, 1, oinfo, resv);
> > + __xfs_bmap_add_free(sc->tp, fsbno, 1, oinfo, true);
>
> xfs_free_extent() sets skip_discard to false and this changes it to
> true. Intentional?
Nope. Will fix this (and the comment in the previous patch).
--D
> Otherwise the rest looks straightforward.
>
> Brian
>
> > + (*deferred)++;
> > + need_roll = *deferred > 100;
> > }
> > if (agf_bp != sc->sa.agf_bp)
> > xfs_trans_brelse(sc->tp, agf_bp);
> > - if (error)
> > + if (error || !need_roll)
> > return error;
> >
> > + *deferred = 0;
> > if (sc->ip)
> > return xfs_trans_roll_inode(&sc->tp, sc->ip);
> > return xrep_roll_ag_trans(sc);
> > @@ -594,6 +607,7 @@ xrep_reap_extents(
> > struct xfs_bitmap_range *bmr;
> > struct xfs_bitmap_range *n;
> > xfs_fsblock_t fsbno;
> > + unsigned int deferred = 0;
> > int error = 0;
> >
> > ASSERT(xfs_sb_version_hasrmapbt(&sc->mp->m_sb));
> > @@ -605,12 +619,17 @@ xrep_reap_extents(
> > XFS_FSB_TO_AGNO(sc->mp, fsbno),
> > XFS_FSB_TO_AGBNO(sc->mp, fsbno), 1);
> >
> > - error = xrep_reap_block(sc, fsbno, oinfo, type);
> > + error = xrep_reap_block(sc, fsbno, oinfo, type, &deferred);
> > if (error)
> > break;
> > }
> >
> > - return error;
> > + if (error || deferred == 0)
> > + return error;
> > +
> > + if (sc->ip)
> > + return xfs_trans_roll_inode(&sc->tp, sc->ip);
> > + return xrep_roll_ag_trans(sc);
> > }
> >
> > /*
> >
