OpenZFS 8023 - Panic destroying a metaslab deferred range tree

Authored by: George Wilson <[email protected]>
Approved by: Dan McDonald <[email protected]>
Reviewed by: Brad Lewis <[email protected]>
Reviewed by: Matt Ahrens <[email protected]>
Reviewed by: Dan Kimmel <[email protected]>
Reviewed by: Saso Kiselkov <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed-by: George Melikov <[email protected]>
Ported-by: Giuseppe Di Natale <[email protected]>

We don't want to dirty any data when we're in the final txgs of the pool
export logic. This change introduces checks to make sure that no data is
dirtied after a certain point. It also addresses the culprit of this
specific bug – the space map cannot be upgraded when we're in final
stages of pool export. If we encounter a space map that wants to be
upgraded in this phase, then we simply ignore the request as it will get
retried the next time we set the fragmentation metric on that metaslab.

OpenZFS-issue: https://www.illumos.org/issues/8023
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/2ef00f5
Closes #5991

1 files changed, 1 insertions, 0 deletions

diff --git a/module/zfs/dbuf.c b/module/zfs/dbuf.c
index ce99fd54c..096d18358 100644
--- a/module/zfs/dbuf.c
+++ b/module/zfs/dbuf.c
@@ -1639,6 +1639,7 @@ dbuf_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx)
 	 * this assertion only if we're not already dirty.
 	 */
 	os = dn->dn_objset;
+	VERIFY3U(tx->tx_txg, <=, spa_final_dirty_txg(os->os_spa));
 #ifdef DEBUG
 	if (dn->dn_objset->os_dsl_dataset != NULL)
 		rrw_enter(&os->os_dsl_dataset->ds_bp_rwlock, RW_READER, FTAG);