MFV r275550:

In addition to r273158, make the code in spa_sync() that checks if the
current TXG is a no-op TXG less fragile.

Illumos issue:
    5347 idle pool may run itself out of space

MFC after:	2 weeks

1 files changed, 7 insertions, 3 deletions

diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_scan.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_scan.c
index 8923151..ffa940e 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_scan.c
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_scan.c
@@ -1486,11 +1486,15 @@ dsl_scan_sync(dsl_pool_t *dp, dmu_tx_t *tx)
 			    dp->dp_bptree_obj, tx));
 			dp->dp_bptree_obj = 0;
 			scn->scn_async_destroying = B_FALSE;
+			scn->scn_async_stalled = B_FALSE;
 		} else {
 			/*
-			 * If we didn't make progress, mark the async destroy as
-			 * stalled, so that we will not initiate a spa_sync() on
-			 * its behalf.
+			 * If we didn't make progress, mark the async
+			 * destroy as stalled, so that we will not initiate
+			 * a spa_sync() on its behalf.  Note that we only
+			 * check this if we are not finished, because if the
+			 * bptree had no blocks for us to visit, we can
+			 * finish without "making progress".
 			 */
 			scn->scn_async_stalled =
 			    (scn->scn_visited_this_txg == 0);