[PATCH v3 2/2] btrfs/291: fix state transition logic and add size requirement

[Disha Goel <disgoel@linux.ibm.com>]

This patch fixes two issues in btrfs/291:

1. Add dynamic LOGWRITES_DEV size requirement based on SCRATCH_DEV
   The test creates LVM snapshots at each FUA point during replay,
   requiring significant space. Calculate the required size as 120%
   of SCRATCH_DEV size (adding 20% overhead for LVM snapshots and
   metadata) to ensure the test works regardless of SCRATCH_DEV size.

2. Fix state transition logic for verity enablement
   The original test assumed orphan items would always be created
   during verity enablement (state 0->1 transition). However, in
   some cases verity completes without creating orphan items,
   causing the test to fail with "expected to reach verity done state".

   Fix by transitioning to state 1 when either orphan items exist
   OR merkle items appear, handling both verity enablement paths.
   Also improve state 1 validation to only check for cleared merkle
   items when measurement actually fails.

The test now correctly handles verity enablement with or without
orphan items while maintaining crash consistency validation, and
works with any SCRATCH_DEV size.

Suggested-by: Anand Jain <anajain.sg@gmail.com>
Signed-off-by: Disha Goel <disgoel@linux.ibm.com>
---
v2 -> v3:
- Calculate LOGWRITES_DEV size requirement dynamically based on SCRATCH_DEV
  size (120% of SCRATCH_DEV) instead of fixed 9GB
- This fixes test failures when SCRATCH_DEV > 9GB, as reported by Anand

 tests/btrfs/291 | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/tests/btrfs/291 b/tests/btrfs/291
index 122aeaa5..e5ea4b50 100755
--- a/tests/btrfs/291
+++ b/tests/btrfs/291
@@ -36,7 +36,9 @@ _cleanup()
 _require_scratch
 _require_test
 _require_loop
-_require_log_writes
+scratch_size=$(_get_device_size $SCRATCH_DEV)
+required_log_size=$((scratch_size * 120 / 100))
+_require_log_writes_sized $required_log_size
 _require_dm_target snapshot
 _require_command $LVM_PROG lvm
 _require_scratch_verity
@@ -129,9 +131,14 @@ do
 	_udev_wait /dev/mapper/$vgname-$snapname
 
 	orphan=$(count_item $snap_dev ORPHAN)
-	[ $state -eq 0 ] && [ $orphan -gt 0 ] && state=1
-
 	pre_mount=$(count_merkle_items $snap_dev)
+
+	if [ $state -eq 0 ]; then
+		if [ $orphan -gt 0 ] || [ $pre_mount -gt 0 ]; then
+			state=1
+		fi
+	fi
+
 	_mount $snap_dev $SCRATCH_MNT || _fail "mount failed at entry $cur"
 	fsverity measure $SCRATCH_MNT/fsv >>$seqres.full 2>&1
 	measured=$?
@@ -143,8 +150,10 @@ do
 	echo "entry: $cur, state: $state, orphan: $orphan, pre_mount: $pre_mount, post_mount: $post_mount" >> $seqres.full
 
 	if [ $state -eq 1 ]; then
-		[ $post_mount -eq 0 ] || \
-			_fail "mount failed to clear under-construction merkle items pre: $pre_mount, post: $post_mount at entry $cur";
+		if [ $measured -ne 0 ]; then
+			[ $post_mount -eq 0 ] || \
+				_fail "mount failed to clear under-construction merkle items pre: $pre_mount, post: $post_mount at entry $cur";
+		fi
 	fi
 	if [ $state -eq 2 ]; then
 		[ $pre_mount -gt 0 ] || \
-- 
2.45.1