Illumos 6537 - Panic on zpool scrub with DEBUG kernel

6537 Panic on zpool scrub with DEBUG kernel
Reviewed by: Steve Gonczi <gonczi@comcast.net>
Reviewed by: Dan McDonald <danmcd@omniti.com>
Reviewed by: Igor Kozhukhov <ikozhukhov@gmail.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Approved by: Matthew Ahrens <mahrens@delphix.com>

References:
  https://www.illumos.org/issues/6537
  https://github.com/illumos/illumos-gate/commit/8c04a1f

Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>

diff --git a/module/zfs/dsl_scan.c b/module/zfs/dsl_scan.c
index 166d0c1eb6e2cbc593cc41d8ff3f0e7513538301..8a5fac25f49859a0406f65aed4afaff645eb78d4 100644 (file)
--- a/module/zfs/dsl_scan.c
+++ b/module/zfs/dsl_scan.c
@@ -21,6 +21,7 @@
 /*
  * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2011, 2015 by Delphix. All rights reserved.
+ * Copyright 2016 Gary Mills
  */
 
 #include <sys/dsl_scan.h>
@@ -1626,7 +1627,8 @@ dsl_scan_sync(dsl_pool_t *dp, dmu_tx_t *tx)
        }
        if (err != 0)
                return;
-       if (!scn->scn_async_destroying && zfs_free_leak_on_eio &&
+       if (dp->dp_free_dir != NULL && !scn->scn_async_destroying &&
+           zfs_free_leak_on_eio &&
            (dsl_dir_phys(dp->dp_free_dir)->dd_used_bytes != 0 ||
            dsl_dir_phys(dp->dp_free_dir)->dd_compressed_bytes != 0 ||
            dsl_dir_phys(dp->dp_free_dir)->dd_uncompressed_bytes != 0)) {
@@ -1652,7 +1654,7 @@ dsl_scan_sync(dsl_pool_t *dp, dmu_tx_t *tx)
                    -dsl_dir_phys(dp->dp_free_dir)->dd_compressed_bytes,
                    -dsl_dir_phys(dp->dp_free_dir)->dd_uncompressed_bytes, tx);
        }
-       if (!scn->scn_async_destroying) {
+       if (dp->dp_free_dir != NULL && !scn->scn_async_destroying) {
                /* finished; verify that space accounting went to zero */
                ASSERT0(dsl_dir_phys(dp->dp_free_dir)->dd_used_bytes);
                ASSERT0(dsl_dir_phys(dp->dp_free_dir)->dd_compressed_bytes);