From: Darrick J. Wong <djwong@xxxxxxxxxx>
Calculate the maximum number of CoW staging extents that can be reaped
in a single transaction chain. The rough calculation here is:
nr_extents = (logres - reservation used by any one step) /
(space used by intents per extent)
Signed-off-by: "Darrick J. Wong" <djwong@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
---
fs/xfs/scrub/trace.h | 1 +
fs/xfs/scrub/reap.c | 71 +++++++++++++++++++++++++++++++++++++++++++++++---
2 files changed, 68 insertions(+), 4 deletions(-)
diff --git a/fs/xfs/scrub/trace.h b/fs/xfs/scrub/trace.h
index a9da22f50534cb..1a994d339c42cf 100644
--- a/fs/xfs/scrub/trace.h
+++ b/fs/xfs/scrub/trace.h
@@ -2042,6 +2042,7 @@ DEFINE_EVENT(xrep_reap_limits_class, name, \
TP_ARGS(tp, per_binval, max_binval, step_size, per_intent, max_deferred))
DEFINE_REPAIR_REAP_LIMITS_EVENT(xreap_agextent_limits);
DEFINE_REPAIR_REAP_LIMITS_EVENT(xreap_agcow_limits);
+DEFINE_REPAIR_REAP_LIMITS_EVENT(xreap_rgcow_limits);
DECLARE_EVENT_CLASS(xrep_reap_find_class,
TP_PROTO(const struct xfs_group *xg, xfs_agblock_t agbno,
diff --git a/fs/xfs/scrub/reap.c b/fs/xfs/scrub/reap.c
index aaef7e6771a045..b2f089e2c49daa 100644
--- a/fs/xfs/scrub/reap.c
+++ b/fs/xfs/scrub/reap.c
@@ -984,7 +984,7 @@ xreap_rgextent_iter(
rtbno = xfs_rgbno_to_rtb(sc->sr.rtg, rgbno);
/*
- * If there are other rmappings, this block is cross linked and must
+ * t1: There are other rmappings; this block is cross linked and must
* not be freed. Remove the forward and reverse mapping and move on.
*/
if (crosslinked) {
@@ -999,7 +999,7 @@ xreap_rgextent_iter(
trace_xreap_dispose_free_extent(rtg_group(sc->sr.rtg), rgbno, *rglenp);
/*
- * The CoW staging extent is not crosslinked. Use deferred work items
+ * t2: The CoW staging extent is not crosslinked. Use deferred work
* to remove the refcountbt records (which removes the rmap records)
* and free the extent. We're not worried about the system going down
* here because log recovery walks the refcount btree to clean out the
@@ -1017,6 +1017,69 @@ xreap_rgextent_iter(
return 0;
}
+/*
+ * Compute the maximum number of intent items that reaping can attach to the
+ * scrub transaction given the worst case log overhead of the intent items
+ * needed to reap a single CoW staging extent. This is not for freeing
+ * metadata blocks.
+ */
+STATIC void
+xreap_configure_rgcow_limits(
+ struct xreap_state *rs)
+{
+ struct xfs_scrub *sc = rs->sc;
+ struct xfs_mount *mp = sc->mp;
+
+ /*
+ * In the worst case, relogging an intent item causes both an intent
+ * item and a done item to be attached to a transaction for each extent
+ * that we'd like to process.
+ */
+ const unsigned int efi = xfs_efi_log_space(1) +
+ xfs_efd_log_space(1);
+ const unsigned int rui = xfs_rui_log_space(1) +
+ xfs_rud_log_space();
+ const unsigned int cui = xfs_cui_log_space(1) +
+ xfs_cud_log_space();
+
+ /*
+ * Various things can happen when reaping non-CoW metadata blocks:
+ *
+ * t1: Unmapping crosslinked CoW blocks: deferred removal of refcount
+ * record, which defers removal of rmap record
+ *
+ * t2: Freeing CoW blocks: deferred removal of refcount record, which
+ * defers removal of rmap record; and deferred removal of the space
+ *
+ * For simplicity, we'll use the worst-case intents size to determine
+ * the maximum number of deferred extents before we have to finish the
+ * whole chain. If we're trying to reap a btree larger than this size,
+ * a crash midway through reaping can result in leaked blocks.
+ */
+ const unsigned int t1 = cui + rui;
+ const unsigned int t2 = cui + rui + efi;
+ const unsigned int per_intent = max(t1, t2);
+
+ /*
+ * For each transaction in a reap chain, we must be able to take one
+ * step in the defer item chain, which should only consist of CUI, EFI,
+ * or RUI items.
+ */
+ const unsigned int f1 = xfs_calc_finish_rt_efi_reservation(mp, 1);
+ const unsigned int f2 = xfs_calc_finish_rt_rui_reservation(mp, 1);
+ const unsigned int f3 = xfs_calc_finish_rt_cui_reservation(mp, 1);
+ const unsigned int step_size = max3(f1, f2, f3);
+
+ /*
+ * The only buffer for the rt device is the rtgroup super, so we don't
+ * need to save space for buffer invalidations.
+ */
+ xreap_configure_limits(rs, step_size, per_intent, per_intent, 0);
+
+ trace_xreap_rgcow_limits(sc->tp, 0, 0, step_size, per_intent,
+ rs->max_deferred);
+}
+
#define XREAP_RTGLOCK_ALL (XFS_RTGLOCK_BITMAP | \
XFS_RTGLOCK_RMAP | \
XFS_RTGLOCK_REFCOUNT)
@@ -1100,14 +1163,14 @@ xrep_reap_rtblocks(
.sc = sc,
.oinfo = oinfo,
.resv = XFS_AG_RESV_NONE,
- .max_binval = XREAP_MAX_BINVAL,
- .max_deferred = XREAP_MAX_DEFER_CHAIN,
};
int error;
ASSERT(xfs_has_rmapbt(sc->mp));
ASSERT(sc->ip != NULL);
+ ASSERT(oinfo == &XFS_RMAP_OINFO_COW);
+ xreap_configure_rgcow_limits(&rs);
error = xrtb_bitmap_walk(bitmap, xreap_rtmeta_extent, &rs);
if (error)
return error;
