[PATCH V2] _btrfs_stress_subvolume: Fix race condition by making 'subvolume stress' task to exit gracefully

Chandan Rajendra
2016-03-21T07:40:24Z

The following scenario can occur when running btrfs/066,

Task A Task B Task C

run_test()
- Execute _btrfs_stress_subvolume()
in a background shell.
_btrfs_stress_subvolme()
...
- fork & exec "mount"
Mount subvolume on directory in $TEST_DIR
- Wait for fsstress to finish do_mount()
- kill shell process executing - btrfs_mount()
_btrfs_stress_subvolume()
i.e. Task B.
- Init process becomes the parent
of "subvolume mount" task
i.e. Task C.
- In case subvolume is mounted
(which is not the case),
unmount it.
- Complete mounting subvolume

Hence on the completion of one iteration of run_test(), the subvolume
created inside the filesystem on $SCRATCH_DEV continues to be mounted on
$TEST_DIR/$seq.mnt. Subsequent invocations of run_test() (called for
remaining Btrfs profile configs) fail during _scratch_pool_mkfs.

Instead of killing the 'subvolume stress' task this commit makes
_btrfs_stress_subvolume() to break out of the loop when a file exists
on the filesystem. The commit also makes relevant changes to other
users of _btrfs_stress_subvolume() i.e. btrfs/060, btrfs/065,
btrfs/067 & btrfs/068.

Suggested-by: Eryu Guan <eguan@redhat.com>
Signed-off-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>
---
Changelog:

V1->V2: Instead of named pipes, Use a file to let 'subvolume stress' task know
that it should break from the while loop.

common/rc | 3 ++-
tests/btrfs/060 | 8 ++++++--
tests/btrfs/065 | 8 ++++++--
tests/btrfs/066 | 8 ++++++--
tests/btrfs/067 | 8 ++++++--
tests/btrfs/068 | 8 ++++++--
6 files changed, 32 insertions(+), 11 deletions(-)

diff --git a/common/rc b/common/rc
index 16f5a43..7d971ea 100644
--- a/common/rc
+++ b/common/rc
@@ -3280,9 +3280,10 @@ _btrfs_stress_subvolume()
local btrfs_mnt=$2
local subvol_name=$3
local subvol_mnt=$4
+ local stop_file=$stop_file

mkdir -p $subvol_mnt
- while true; do
+ while [ ! -e $stop_file ]; do
$BTRFS_UTIL_PROG subvolume create $btrfs_mnt/$subvol_name
$MOUNT_PROG -o subvol=$subvol_name $btrfs_dev $subvol_mnt
$UMOUNT_PROG $subvol_mnt
diff --git a/tests/btrfs/060 b/tests/btrfs/060
index 8ef0e7f..6b6a480 100755
--- a/tests/btrfs/060
+++ b/tests/btrfs/060
@@ -56,6 +56,7 @@ run_test()
{
local mkfs_opts=$1
local subvol_mnt=$TEST_DIR/$seq.mnt
+ local stop_file=$TEST_DIR/$seq.stop.$$

echo "Test $mkfs_opts" >>$seqres.full

@@ -77,15 +78,18 @@ run_test()
balance_pid=$!
echo "$balance_pid" >>$seqres.full

+ # make sure the stop sign is not there
+ rm -f $stop_file
echo -n "Start subvolume worker: " >>$seqres.full
- _btrfs_stress_subvolume $SCRATCH_DEV $SCRATCH_MNT subvol_$$ $subvol_mnt >/dev/null 2>&1 &
+ _btrfs_stress_subvolume $SCRATCH_DEV $SCRATCH_MNT subvol_$$ $subvol_mnt $stop_file >/dev/null 2>&1 &
subvol_pid=$!
echo "$subvol_pid" >>$seqres.full

echo "Wait for fsstress to exit and kill all background workers" >>$seqres.full
wait $fsstress_pid

- kill $balance_pid $subvol_pid
+ touch $stop_file
+ kill $balance_pid
wait
# wait for the balance operation to finish
while ps aux | grep "balance start" | grep -qv grep; do
diff --git a/tests/btrfs/065 b/tests/btrfs/065
index 7d8249b..a4afe73 100755
--- a/tests/btrfs/065
+++ b/tests/btrfs/065
@@ -58,6 +58,7 @@ run_test()
local mkfs_opts=$1
local saved_scratch_dev_pool=$SCRATCH_DEV_POOL
local subvol_mnt=$TEST_DIR/$seq.mnt
+ local stop_file=$TEST_DIR/$seq.stop.$$

echo "Test $mkfs_opts" >>$seqres.full

@@ -80,8 +81,10 @@ run_test()
$FSSTRESS_PROG $args >/dev/null 2>&1 &
fsstress_pid=$!

+ # make sure the stop sign is not there
+ rm -f $stop_file
echo -n "Start subvolume worker: " >>$seqres.full
- _btrfs_stress_subvolume $SCRATCH_DEV $SCRATCH_MNT subvol_$$ $subvol_mnt >/dev/null 2>&1 &
+ _btrfs_stress_subvolume $SCRATCH_DEV $SCRATCH_MNT subvol_$$ $subvol_mnt $stop_file >/dev/null 2>&1 &
subvol_pid=$!
echo "$subvol_pid" >>$seqres.full

@@ -93,7 +96,8 @@ run_test()
echo "Wait for fsstress to exit and kill all background workers" >>$seqres.full
wait $fsstress_pid

- kill $subvol_pid $replace_pid
+ touch $stop_file
+ kill $replace_pid
wait
# wait for the replace operation to finish
while ps aux | grep "replace start" | grep -qv grep; do
diff --git a/tests/btrfs/066 b/tests/btrfs/066
index 2d9a1d2..cf4dd0d 100755
--- a/tests/btrfs/066
+++ b/tests/btrfs/066
@@ -56,6 +56,7 @@ run_test()
{
local mkfs_opts=$1
local subvol_mnt=$TEST_DIR/$seq.mnt
+ local stop_file=$TEST_DIR/$seq.stop.$$

echo "Test $mkfs_opts" >>$seqres.full

@@ -72,8 +73,10 @@ run_test()
$FSSTRESS_PROG $args >/dev/null 2>&1 &
fsstress_pid=$!

+ # make sure the stop sign is not there
+ rm -f $stop_file
echo -n "Start subvolume worker: " >>$seqres.full
- _btrfs_stress_subvolume $SCRATCH_DEV $SCRATCH_MNT subvol_$$ $subvol_mnt >/dev/null 2>&1 &
+ _btrfs_stress_subvolume $SCRATCH_DEV $SCRATCH_MNT subvol_$$ $subvol_mnt $stop_file >/dev/null 2>&1 &
subvol_pid=$!
echo "$subvol_pid" >>$seqres.full

@@ -85,7 +88,8 @@ run_test()
echo "Wait for fsstress to exit and kill all background workers" >>$seqres.full
wait $fsstress_pid

- kill $subvol_pid $scrub_pid
+ touch $stop_file
+ kill $scrub_pid
wait
# wait for the scrub operation to finish
while ps aux | grep "scrub start" | grep -qv grep; do
diff --git a/tests/btrfs/067 b/tests/btrfs/067
index 2c1e284..b76f5ec 100755
--- a/tests/btrfs/067
+++ b/tests/btrfs/067
@@ -57,6 +57,7 @@ run_test()
local mkfs_opts=$1
local with_compress=$2
local subvol_mnt=$TEST_DIR/$seq.mnt
+ local stop_file=$TEST_DIR/$seq.stop.$$

echo "Test $mkfs_opts with $with_compress" >>$seqres.full

@@ -73,8 +74,10 @@ run_test()
$FSSTRESS_PROG $args >/dev/null 2>&1 &
fsstress_pid=$!

+ # make sure the stop sign is not there
+ rm -f $stop_file
echo -n "Start subvolume worker: " >>$seqres.full
- _btrfs_stress_subvolume $SCRATCH_DEV $SCRATCH_MNT subvol_$$ $subvol_mnt >/dev/null 2>&1 &
+ _btrfs_stress_subvolume $SCRATCH_DEV $SCRATCH_MNT subvol_$$ $subvol_mnt $stop_file >/dev/null 2>&1 &
subvol_pid=$!
echo "$subvol_pid" >>$seqres.full

@@ -86,7 +89,8 @@ run_test()
echo "Wait for fsstress to exit and kill all background workers" >>$seqres.full
wait $fsstress_pid

- kill $subvol_pid $defrag_pid
+ touch $stop_file
+ kill $defrag_pid
wait
# wait for btrfs defrag process to exit, otherwise it will block umount
while ps aux | grep "btrfs filesystem defrag" | grep -qv grep; do
diff --git a/tests/btrfs/068 b/tests/btrfs/068
index 3126ec2..534aee6 100755
--- a/tests/btrfs/068
+++ b/tests/btrfs/068
@@ -57,6 +57,7 @@ run_test()
{
local mkfs_opts=$1
local subvol_mnt=$TEST_DIR/$seq.mnt
+ local stop_file=$TEST_DIR/$seq.stop.$$

echo "Test $mkfs_opts with $with_compress" >>$seqres.full

@@ -73,8 +74,10 @@ run_test()
$FSSTRESS_PROG $args >/dev/null 2>&1 &
fsstress_pid=$!

+ # make sure the stop sign is not there
+ rm -f $stop_file
echo -n "Start subvolume worker: " >>$seqres.full
- _btrfs_stress_subvolume $SCRATCH_DEV $SCRATCH_MNT subvol_$$ $subvol_mnt >/dev/null 2>&1 &
+ _btrfs_stress_subvolume $SCRATCH_DEV $SCRATCH_MNT subvol_$$ $subvol_mnt $stop_file >/dev/null 2>&1 &
subvol_pid=$!
echo "$subvol_pid" >>$seqres.full

@@ -86,7 +89,8 @@ run_test()
echo "Wait for fsstress to exit and kill all background workers" >>$seqres.full
wait $fsstress_pid

- kill $subvol_pid $remount_pid
+ touch $stop_file
+ kill $remount_pid
wait
# wait for the remount loop process to finish
while ps aux | grep "mount.*$SCRATCH_MNT" | grep -qv grep; do
--
2.1.0