Illumos 5243 - zdb -b could be much faster

5243 zdb -b could be much faster
Reviewed by: Christopher Siden <[email protected]>
Reviewed by: George Wilson <[email protected]>
Reviewed by: Richard Elling <[email protected]>
Approved by: Dan McDonald <[email protected]>

References:
  https://www.illumos.org/issues/5243
  https://github.com/illumos/illumos-gate/commit/f7950bf

Ported-by: Don Brady <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
Closes #3414

1 files changed, 22 insertions, 19 deletions

diff --git a/module/zfs/dmu_traverse.c b/module/zfs/dmu_traverse.c
index 21e34f822..8673132a0 100644
--- a/module/zfs/dmu_traverse.c
+++ b/module/zfs/dmu_traverse.c
@@ -58,6 +58,7 @@ typedef struct traverse_data {
 	int td_flags;
 	prefetch_data_t *td_pfd;
 	boolean_t td_paused;
+	uint64_t td_hole_birth_enabled_txg;
 	blkptr_cb_t *td_func;
 	void *td_arg;
 } traverse_data_t;
@@ -226,25 +227,20 @@ traverse_visitbp(traverse_data_t *td, const dnode_phys_t *dnp,
 	}
 
 	if (bp->blk_birth == 0) {
-		if (spa_feature_is_active(td->td_spa, SPA_FEATURE_HOLE_BIRTH)) {
-			/*
-			 * Since this block has a birth time of 0 it must be a
-			 * hole created before the SPA_FEATURE_HOLE_BIRTH
-			 * feature was enabled.  If SPA_FEATURE_HOLE_BIRTH
-			 * was enabled before the min_txg for this traveral we
-			 * know the hole must have been created before the
-			 * min_txg for this traveral, so we can skip it. If
-			 * SPA_FEATURE_HOLE_BIRTH was enabled after the min_txg
-			 * for this traveral we cannot tell if the hole was
-			 * created before or after the min_txg for this
-			 * traversal, so we cannot skip it.
-			 */
-			uint64_t hole_birth_enabled_txg;
-			VERIFY(spa_feature_enabled_txg(td->td_spa,
-			    SPA_FEATURE_HOLE_BIRTH, &hole_birth_enabled_txg));
-			if (hole_birth_enabled_txg < td->td_min_txg)
-				return (0);
-		}
+		/*
+		 * Since this block has a birth time of 0 it must be a
+		 * hole created before the SPA_FEATURE_HOLE_BIRTH
+		 * feature was enabled.  If SPA_FEATURE_HOLE_BIRTH
+		 * was enabled before the min_txg for this traveral we
+		 * know the hole must have been created before the
+		 * min_txg for this traveral, so we can skip it. If
+		 * SPA_FEATURE_HOLE_BIRTH was enabled after the min_txg
+		 * for this traveral we cannot tell if the hole was
+		 * created before or after the min_txg for this
+		 * traversal, so we cannot skip it.
+		 */
+		if (td->td_hole_birth_enabled_txg < td->td_min_txg)
+			return (0);
 	} else if (bp->blk_birth <= td->td_min_txg) {
 		return (0);
 	}
@@ -533,6 +529,13 @@ traverse_impl(spa_t *spa, dsl_dataset_t *ds, uint64_t objset, blkptr_t *rootbp,
 	td->td_flags = flags;
 	td->td_paused = B_FALSE;
 
+	if (spa_feature_is_active(spa, SPA_FEATURE_HOLE_BIRTH)) {
+		VERIFY(spa_feature_enabled_txg(spa,
+		    SPA_FEATURE_HOLE_BIRTH, &td->td_hole_birth_enabled_txg));
+	} else {
+		td->td_hole_birth_enabled_txg = 0;
+	}
+
 	pd->pd_flags = flags;
 	mutex_init(&pd->pd_mtx, NULL, MUTEX_DEFAULT, NULL);
 	cv_init(&pd->pd_cv, NULL, CV_DEFAULT, NULL);