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

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

[Kaiwen Hu]

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

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

[Filipe Manana]

On Tue, Mar 29, 2022 at 06:02:02PM +0800, Kaiwen Hu wrote:
> 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(+)

Thanks for doing this.

However we don't change existing tests to exercise bugs.

The few exceptions where we change an existing test case are, typically,
if the test case is very recent and we didn't get it quite right, or
if we had a filesystem behaviour change that makes the test fail - like
for example the recent changes that allow cross mount reflink operations.

So this should be a new test case.

> 
> 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
>