OpenZFS 9456 - ztest failure in zil_commit_waiter_timeout

Problem
=======

Illumos bug 8373 was integrated, which now presents a code path where
"dmu_tx_assign" can fail.  When "dmu_tx_assign" fails, it will not issue
the lwb that was passed in to "zil_lwb_write_issue".  As a result, when
"zil_lwb_write_issue" returns, the lwb will still be in the "opened"
state, just as it was when "zil_lwb_write_issue" was originally called.

Solution
========

As a result of this new call path, the failed assertion needs to be
modified to be aware of this new possibility. Thus, we can only assert
that the lwb is no longer in the "opened" state if the returned lwb is
non-null, since we cannot differentiate between the case of
"dmu_tx_assign" failing or "zio_alloc_zil" failing within the call to
"zil_lwb_write_issue".

Authored by: Prakash Surya <prakash.surya@delphix.com>
Reviewed by: Matt Ahrens <matt@delphix.com>
Reviewed by: Serapheim Dimitropoulos <serapheim.dimitro@delphix.com>
Reviewed by: Prakash Surya <prakash.surya@delphix.com>
Reviewed by: George Melikov <mail@gmelikov.ru>
Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>
Approved by: Matt Ahrens <mahrens@delphix.com>

OpenZFS-issue: https://www.illumos.org/issues/9456
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/a8b09f4e
Closes #7695

diff --git a/module/zfs/zil.c b/module/zfs/zil.c
index d0b1c1d14896b5eb5ad2a38b6cd795013827d5a3..f7c793d40a4fdae5d297301a3bd77452b2ab7b6d 100644 (file)
--- a/module/zfs/zil.c
+++ b/module/zfs/zil.c
@@ -2399,7 +2399,7 @@ zil_commit_waiter_timeout(zilog_t *zilog, zil_commit_waiter_t *zcw)
         */
        lwb_t *nlwb = zil_lwb_write_issue(zilog, lwb);
 
-       ASSERT3S(lwb->lwb_state, !=, LWB_STATE_OPENED);
+       IMPLY(nlwb != NULL, lwb->lwb_state != LWB_STATE_OPENED);
 
        /*
         * Since the lwb's zio hadn't been issued by the time this thread