[PATCH] btrfs: test that we can't delete subvolume within swapfile

[Kaiwen Hu <kevinhu@synology.com>]

Subvolumes with active swapfiles should be forbidden
to be deleted, because when the subvolume is deleted,
we cannot swapoff the swapfile in the deleted subvolume.

Fixed by the patch
	btrfs: prevent subvol with swapfile from being deleted

Reviewed-by: Robbie Ko <robbieko@synology.com>
Signed-off-by: Kaiwen Hu <kevinhu@synology.com>
---
 tests/btrfs/174     | 10 ++++++++++
 tests/btrfs/174.out |  3 +++
 2 files changed, 13 insertions(+)

diff --git a/tests/btrfs/174 b/tests/btrfs/174
index 3bb5e7f9..08d4af40 100755
--- a/tests/btrfs/174
+++ b/tests/btrfs/174
@@ -11,6 +11,7 @@
 _begin_fstest auto quick swap
 
 . ./common/filter
+. ./common/filter.btrfs
 
 _supported_fs btrfs
 _require_scratch_swapfile
@@ -43,7 +44,16 @@ echo "Defrag"
 # fragmented.
 $BTRFS_UTIL_PROG filesystem defrag -c "$swapfile" 2>&1 | grep -o "Text file busy"
 
+# We cannot delete sub-volume when the sub-volume contains active swapfile.
+echo "Delete subvol"
+$BTRFS_UTIL_PROG subvolume delete "$SCRATCH_MNT/swapvol" \
+	2>&1 | grep -o "Text file busy"
+
 swapoff "$swapfile"
+
+# Delete the sub-volume
+$BTRFS_UTIL_PROG subvolume delete $SCRATCH_MNT/swapvol | _filter_btrfs_subvol_delete
+
 _scratch_unmount
 
 status=0
diff --git a/tests/btrfs/174.out b/tests/btrfs/174.out
index 15bdf79e..8bed461b 100644
--- a/tests/btrfs/174.out
+++ b/tests/btrfs/174.out
@@ -8,3 +8,6 @@ Snapshot
 Text file busy
 Defrag
 Text file busy
+Delete subvol
+Text file busy
+Delete subvolume 'SCRATCH_MNT/swapvol'
-- 
2.25.1