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?
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);
> }
>
> /*
>
