linux-kernel - [PATCH v2 1/3] fstests: use udevadm settle after pvremove

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Date:   Wed, 11 Aug 2021 08:45:10 -0700
From:   Luis Chamberlain <mcgrof@...nel.org>
To:     fstests@...r.kernel.org
Cc:     hare@...e.de, dgilbert@...erlog.com, jeyu@...nel.org,
        lucas.demarchi@...el.com, linux-kernel@...r.kernel.org,
        Luis Chamberlain <mcgrof@...nel.org>
Subject: [PATCH v2 1/3] fstests: use udevadm settle after pvremove

As with creation, we also need to use udevadm settle
when removing a pv, otherwise we can trip on races with
module removals for the block devices in use.

This reduces the amount of time in which a block device
module refcnt for test modules such as scsi_debug spends
outside of 0.

Races with the refcnt being greater than 0 means module
removal can fail causing false positives. This helps
ensure that the pv is really long gone. These issues
are tracked for scsi_debug [0] and later found to be a
generic issue regardless of filesystem with pvremove [1].

Using udevadm settle *helps*, it does not address all
possible races with the refcnt as noted in the generic
bug entry [1].

[0] https://bugzilla.kernel.org/show_bug.cgi?id=212337
[1] https://bugzilla.kernel.org/show_bug.cgi?id=214015
Signed-off-by: Luis Chamberlain <mcgrof@...nel.org>
---
 tests/generic/081 | 5 ++++-
 tests/generic/108 | 1 +
 tests/generic/459 | 1 +
 3 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/tests/generic/081 b/tests/generic/081
index f795b2c1..8e552074 100755
--- a/tests/generic/081
+++ b/tests/generic/081
@@ -12,6 +12,7 @@ _begin_fstest auto quick
 # Override the default cleanup function.
 _cleanup()
 {
+	local pv_ret
 	cd /
 	rm -f $tmp.*
 
@@ -34,7 +35,9 @@ _cleanup()
 		$UMOUNT_PROG $mnt >> $seqres.full 2>&1
 		$LVM_PROG vgremove -f $vgname >>$seqres.full 2>&1
 		$LVM_PROG pvremove -f $SCRATCH_DEV >>$seqres.full 2>&1
-		test $? -eq 0 && break
+		pv_ret=$?
+		$UDEV_SETTLE_PROG
+		test $pv_ret -eq 0 && break
 		sleep 2
 	done
 }
diff --git a/tests/generic/108 b/tests/generic/108
index 7dd426c1..b7797e8f 100755
--- a/tests/generic/108
+++ b/tests/generic/108
@@ -21,6 +21,7 @@ _cleanup()
 	$UMOUNT_PROG $SCRATCH_MNT >>$seqres.full 2>&1
 	$LVM_PROG vgremove -f $vgname >>$seqres.full 2>&1
 	$LVM_PROG pvremove -f $SCRATCH_DEV $SCSI_DEBUG_DEV >>$seqres.full 2>&1
+	$UDEV_SETTLE_PROG
 	_put_scsi_debug_dev
 	rm -f $tmp.*
 }
diff --git a/tests/generic/459 b/tests/generic/459
index e5e5e9ab..5b44e245 100755
--- a/tests/generic/459
+++ b/tests/generic/459
@@ -29,6 +29,7 @@ _cleanup()
 	$UMOUNT_PROG $SCRATCH_MNT >>$seqres.full 2>&1
 	$LVM_PROG vgremove -ff $vgname >>$seqres.full 2>&1
 	$LVM_PROG pvremove -ff $SCRATCH_DEV >>$seqres.full 2>&1
+	$UDEV_SETTLE_PROG
 }
 
 # Import common functions.
-- 
2.30.2