MFV r353615: 9485 Optimize possible split block search space

illumos/illumos-gate@a21fe349793c3805ec504bbe5e9acf06c2d63d7a
https://github.com/illumos/illumos-gate/commit/a21fe349793c3805ec504bbe5e9acf06c2d63d7a

https://www.illumos.org/issues/9485
  Port this commit from ZoL:
  https://github.com/zfsonlinux/zfs/commit/4589f3ae4c1bb435777da8640eb915f3c713b14d

Author: Brian Behlendorf <behlendorf1@llnl.gov>
Obtained from:	illumos, ZoL
MFC after:	3 weeks

1 files changed, 10 insertions, 1 deletions

diff --git a/cddl/contrib/opensolaris/cmd/ztest/ztest.c b/cddl/contrib/opensolaris/cmd/ztest/ztest.c
index 538fd040c95e..e4382d0f3959 100644
--- a/cddl/contrib/opensolaris/cmd/ztest/ztest.c
+++ b/cddl/contrib/opensolaris/cmd/ztest/ztest.c
@@ -198,6 +198,7 @@ extern boolean_t zfs_compressed_arc_enabled;
 extern boolean_t zfs_abd_scatter_enabled;
 extern int dmu_object_alloc_chunk_shift;
 extern boolean_t zfs_force_some_double_word_sm_entries;
+extern unsigned long zfs_reconstruct_indirect_damage_fraction;
 
 static ztest_shared_opts_t *ztest_shared_opts;
 static ztest_shared_opts_t ztest_opts;
@@ -5696,7 +5697,8 @@ ztest_run_zdb(char *pool)
 	isa = strdup(isa);
 	/* LINTED */
 	(void) sprintf(bin,
-	    "/usr/sbin%.*s/zdb -bcc%s%s -G -d -U %s %s",
+	    "/usr/sbin%.*s/zdb -bcc%s%s -G -d -U %s "
+	    "-o zfs_reconstruct_indirect_combinations_max=65536 %s",
 	    isalen,
 	    isa,
 	    ztest_opts.zo_verbose >= 3 ? "s" : "",
@@ -6653,6 +6655,13 @@ main(int argc, char **argv)
 	 */
 	zfs_force_some_double_word_sm_entries = B_TRUE;
 
+	/*
+	 * Verify that even extensively damaged split blocks with many
+	 * segments can be reconstructed in a reasonable amount of time
+	 * when reconstruction is known to be possible.
+	 */
+	zfs_reconstruct_indirect_damage_fraction = 4;
+
 	ztest_fd_rand = open("/dev/urandom", O_RDONLY);
 	ASSERT3S(ztest_fd_rand, >=, 0);