Report holes when there are only metadata changes

Update the dirty check in dmu_offset_next() such that dnode's are only considered dirty for the purpose or reporting holes when there are pending data blocks or frees to be synced. This ensures that when there are only metadata updates to be synced (atime) that holes are reported. Reviewed-by: Debabrata Banerjee <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes openzfs#6958 Closes openzfs#8505
BlueArchive · Mar 21, 2019 · ec4f9b8 · ec4f9b8
1 parent 066da71
commit ec4f9b8
Showing 1 changed file with 28 additions and 3 deletions.
diff --git a/module/zfs/dmu.c b/module/zfs/dmu.c
@@ -2366,14 +2366,39 @@ dmu_offset_next(objset_t *os, uint64_t object, boolean_t hole, uint64_t *off)
 		return (err);
 
 	/*
-	 * Check if dnode is dirty
+	 * Check if there are dirty data blocks or frees which have not been
+	 * synced.  Dirty spill and bonus blocks which are external to the
+	 * object can ignored when reporting holes.
 	 */
+	mutex_enter(&dn->dn_mtx);
 	for (i = 0; i < TXG_SIZE; i++) {
 		if (multilist_link_active(&dn->dn_dirty_link[i])) {
-			clean = B_FALSE;
-			break;
+
+			if (dn->dn_free_ranges[i] != NULL) {
+				clean = B_FALSE;
+				break;
+			}
+
+			list_t *list = &dn->dn_dirty_records[i];
+			dbuf_dirty_record_t *dr;
+
+			for (dr = list_head(list); dr != NULL;
+			    dr = list_next(list, dr)) {
+				dmu_buf_impl_t *db = dr->dr_dbuf;
+
+				if (db->db_blkid == DMU_SPILL_BLKID ||
+				    db->db_blkid == DMU_BONUS_BLKID)
+					continue;
+
+				clean = B_FALSE;
+				break;
+			}
 		}
+
+		if (clean == B_FALSE)
+			break;
 	}
+	mutex_exit(&dn->dn_mtx);
 
 	/*
 	 * If compatibility option is on, sync any current changes before