From: Filipe Manana <fdmanana@xxxxxxxx>
btrfs/213 writes data, in 1M extents, for 4 seconds into a file, then
triggers a balance and then after 2 seconds it tries to cancel the
balance operation. More often than not, this works because the balance
is still running after 2 seconds. However it also fails sporadically
because balance has finished in less than 2 seconds, which is plausible
since data and metadata are cached or other factors such as virtualized
environment. When that's the case, it fails like this:
$ ./check btrfs/213
FSTYP -- btrfs
PLATFORM -- Linux/x86_64 debian0 6.4.0-rc1-btrfs-next-131+ #1 SMP PREEMPT_DYNAMIC Thu May 11 11:26:19 WEST 2023
MKFS_OPTIONS -- /dev/sdc
MOUNT_OPTIONS -- /dev/sdc /home/fdmanana/btrfs-tests/scratch_1
btrfs/213 51s ... - output mismatch (see /home/fdmanana/git/hub/xfstests/results//btrfs/213.out.bad)
--- tests/btrfs/213.out 2020-06-10 19:29:03.822519250 +0100
+++ /home/fdmanana/git/hub/xfstests/results//btrfs/213.out.bad 2023-05-17 15:39:32.653727223 +0100
@@ -1,2 +1,3 @@
QA output created by 213
+ERROR: balance cancel on '/home/fdmanana/btrfs-tests/scratch_1' failed: Not in progress
Silence is golden
...
(Run 'diff -u /home/fdmanana/git/hub/xfstests/tests/btrfs/213.out /home/fdmanana/git/hub/xfstests/results//btrfs/213.out.bad' to see the entire diff)
Ran: btrfs/213
Failures: btrfs/213
Failed 1 of 1 tests
To make it much less likely that balance has already finished before we
try to cancel it, unmount and mount again the filesystem before starting
balance, to clear cached metadata and data, and also double the time we
spend writing 1M data extents. Also ignore when the balance failed because
it was already finished when we tried to cancel it.
Signed-off-by: Filipe Manana <fdmanana@xxxxxxxx>
---
tests/btrfs/213 | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/tests/btrfs/213 b/tests/btrfs/213
index 8a10355c..cca0b3cc 100755
--- a/tests/btrfs/213
+++ b/tests/btrfs/213
@@ -28,7 +28,7 @@ _require_xfs_io_command pwrite -D
_scratch_mkfs >> $seqres.full
_scratch_mount
-runtime=4
+runtime=8
# Create enough IO so that we need around $runtime seconds to relocate it.
#
@@ -39,11 +39,18 @@ sleep $runtime
kill $write_pid
wait $write_pid
+# Unmount and mount again the fs to clear any cached data and metadata, so that
+# it's less likely balance has already finished when we try to cancel it below.
+_scratch_cycle_mount
+
# Now balance should take at least $runtime seconds, we can cancel it at
# $runtime/2 to ensure a success cancel.
_run_btrfs_balance_start -d --bg "$SCRATCH_MNT"
-sleep $(($runtime / 2))
-$BTRFS_UTIL_PROG balance cancel "$SCRATCH_MNT"
+sleep $(($runtime / 4))
+# It's possible that balance has already completed. It's unlikely but often
+# it may happen due to virtualization, caching and other factors, so ignore
+# any error about no balance currently running.
+$BTRFS_UTIL_PROG balance cancel "$SCRATCH_MNT" 2>&1 | grep -iv 'not in progress'
# Now check if we can finish relocating metadata, which should finish very
# quickly.
--
2.34.1
