From c454e46336c31d3fe2c6491c57b1e71963ca7ed6 Mon Sep 17 00:00:00 2001
From: Brian Behlendorf <behlendorf1@llnl.gov>
Date: Wed, 22 Dec 2021 11:05:07 -0800
Subject: [PATCH] ZTS: Fix rollback_003_pos.ksh

Under Linux when rolling back a mounted filesystem negative dentries
may not be dropped from the cache.  This can result in an ENOENT
being incorrectly returned on first access.  Issuing a `df` before
the unmount results in the negative dentries being invalidated and
side steps the issue.

This is solely a workaround for the test case on Linux and not
correct behavior.  The core issue of invalidating negative dentries
needs to be handled with a kernel side change.  This is being
tracked as issue #6143.

Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: John Kennedy <john.kennedy@delphix.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #12898
Issue #6143
---
 tests/test-runner/bin/zts-report.py.in          |  1 -
 .../tests/functional/rsend/rsend.kshlib         |  7 +++++++
 .../functional/snapshot/rollback_003_pos.ksh    | 17 ++++++++++-------
 3 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/tests/test-runner/bin/zts-report.py.in b/tests/test-runner/bin/zts-report.py.in
index 414e266568..d306e04760 100755
--- a/tests/test-runner/bin/zts-report.py.in
+++ b/tests/test-runner/bin/zts-report.py.in
@@ -294,7 +294,6 @@ elif sys.platform.startswith('linux'):
         'mmp/mmp_active_import': ['FAIL', known_reason],
         'mmp/mmp_exported_import': ['FAIL', known_reason],
         'mmp/mmp_inactive_import': ['FAIL', known_reason],
-        'snapshot/rollback_003_pos': ['FAIL', known_reason],
         'zvol/zvol_misc/zvol_misc_snapdev': ['FAIL', '12621'],
         'zvol/zvol_misc/zvol_misc_volmode': ['FAIL', known_reason],
     })
diff --git a/tests/zfs-tests/tests/functional/rsend/rsend.kshlib b/tests/zfs-tests/tests/functional/rsend/rsend.kshlib
index 8cd35e4afd..516d412632 100644
--- a/tests/zfs-tests/tests/functional/rsend/rsend.kshlib
+++ b/tests/zfs-tests/tests/functional/rsend/rsend.kshlib
@@ -121,6 +121,13 @@ function cleanup_pool
 	log_must rm -rf $BACKDIR/*
 
 	if is_global_zone ; then
+		#
+		# Linux: Issuing a `df` seems to properly force any negative
+		# dcache entries to be invalidated preventing failures when
+		# accessing the mount point. Additional investigation required.
+		#
+		# https://github.com/openzfs/zfs/issues/6143
+		#
 		log_must df >/dev/null
 		log_must_busy zfs destroy -Rf $pool
 	else
diff --git a/tests/zfs-tests/tests/functional/snapshot/rollback_003_pos.ksh b/tests/zfs-tests/tests/functional/snapshot/rollback_003_pos.ksh
index 59e7c110dd..036e71410c 100755
--- a/tests/zfs-tests/tests/functional/snapshot/rollback_003_pos.ksh
+++ b/tests/zfs-tests/tests/functional/snapshot/rollback_003_pos.ksh
@@ -92,6 +92,15 @@ log_note "Verify rollback of multiple nested file systems succeeds."
 log_must zfs snapshot $TESTPOOL/$TESTFILE@$TESTSNAP
 log_must zfs snapshot $SNAPPOOL.1
 
+#
+# Linux: Issuing a `df` seems to properly force any negative dcache entries to
+# be invalidated preventing failures when accessing the mount point. Additional
+# investigation required.
+#
+# https://github.com/openzfs/zfs/issues/6143
+#
+log_must df >/dev/null
+
 export __ZFS_POOL_RESTRICT="$TESTPOOL"
 log_must zfs unmount -a
 log_must zfs mount -a
@@ -100,12 +109,6 @@ unset __ZFS_POOL_RESTRICT
 log_must touch /$TESTPOOL/$TESTFILE/$TESTFILE.1
 
 log_must zfs rollback $SNAPPOOL.1
-
-#
-# Workaround for issue #6143.  Issuing a `df` seems to properly force any
-# negative dcache entries to be invalidated preventing subsequent failures
-# when accessing the mount point.  Additional investigation required.
-#
-log_must df
+log_must df >/dev/null
 
 log_pass "Rollbacks succeed when nested file systems are present."