generic/563: use a loop device to avoid partition incompatibility

cgroup writeback accounting does not track partition level
statistics. Instead, I/O is accounted against the parent device. As
a result, the test fails if the scratch device happens to be a
device partition. Since parent level stats are potentially polluted
by factors external to the test, wrap the scratch device in a
loopback device to guarantee the test always runs on a top-level
block device.

Reported-by: Boyang Xue <bxue@redhat.com>
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Zorro Lang <zlang@redhat.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>

diff --git a/tests/generic/563 b/tests/generic/563
index 51deaa2f436a525f200e48dc0f8248a73bb2fc4d..b113eacf60e7eb4f5e87e45663e73fc23cb2bf1b 100755 (executable)
--- a/tests/generic/563
+++ b/tests/generic/563
@@ -2,7 +2,7 @@
 # SPDX-License-Identifier: GPL-2.0
 # Copyright (c) 2019 Red Hat, Inc.  All Rights Reserved.
 #
 # SPDX-License-Identifier: GPL-2.0
 # Copyright (c) 2019 Red Hat, Inc.  All Rights Reserved.
 #

-# FS QA Test No. 011
+# FS QA Test No. 563

 #
 # This test verifies that cgroup aware writeback properly accounts I/Os in
 # various scenarios. We perform reads/writes from different combinations of
 #
 # This test verifies that cgroup aware writeback properly accounts I/Os in
 # various scenarios. We perform reads/writes from different combinations of


@@ -26,6 +26,8 @@ _cleanup()
 
        echo $$ > $cgdir/cgroup.procs
        rmdir $cgdir/$seq-cg* > /dev/null 2>&1
 
        echo $$ > $cgdir/cgroup.procs
        rmdir $cgdir/$seq-cg* > /dev/null 2>&1

+       umount $SCRATCH_MNT > /dev/null 2>&1
+       _destroy_loop_device $LOOP_DEV > /dev/null 2>&1

 }
 
 # get standard environment, filters and checks
 }
 
 # get standard environment, filters and checks


@@ -40,16 +42,14 @@ rm -f $seqres.full
 
 # Modify as appropriate.
 _supported_fs generic
 
 # Modify as appropriate.
 _supported_fs generic

-_require_scratch
+_require_scratch_nocheck

 _require_cgroup2 io
 _require_cgroup2 io

+_require_loop

 
 # cgroup v2 writeback is only support on block devices so far
 _require_block_device $SCRATCH_DEV
 
 
 # cgroup v2 writeback is only support on block devices so far
 _require_block_device $SCRATCH_DEV
 

-smajor=$((0x`stat -L -c %t $SCRATCH_DEV`))
-sminor=$((0x`stat -L -c %T $SCRATCH_DEV`))

 cgdir=$CGROUP2_PATH
 cgdir=$CGROUP2_PATH

-

 iosize=$((1024 * 1024 * 8))
 
 # Check cgroup read/write charges against expected values. Allow for some
 iosize=$((1024 * 1024 * 8))
 
 # Check cgroup read/write charges against expected values. Allow for some


@@ -89,12 +89,19 @@ reset()
        rmdir $cgdir/$seq-cg* > /dev/null 2>&1
        $XFS_IO_PROG -fc "pwrite 0 $iosize" $SCRATCH_MNT/file \
                >> $seqres.full 2>&1
        rmdir $cgdir/$seq-cg* > /dev/null 2>&1
        $XFS_IO_PROG -fc "pwrite 0 $iosize" $SCRATCH_MNT/file \
                >> $seqres.full 2>&1

-       _scratch_cycle_mount || _fail "mount failed"
+       umount $SCRATCH_MNT || _fail "umount failed"
+       _mount $LOOP_DEV $SCRATCH_MNT || _fail "mount failed"

        stat $SCRATCH_MNT/file > /dev/null
 }
 
        stat $SCRATCH_MNT/file > /dev/null
 }
 

-_scratch_mkfs >> $seqres.full 2>&1
-_scratch_mount
+# cgroup I/O accounting doesn't work on partitions. Use a loop device to rule
+# that out.
+LOOP_DEV=$(_create_loop_device $SCRATCH_DEV)
+smajor=$((0x`stat -L -c %t $LOOP_DEV`))
+sminor=$((0x`stat -L -c %T $LOOP_DEV`))
+
+_mkfs_dev $LOOP_DEV >> $seqres.full 2>&1
+_mount $LOOP_DEV $SCRATCH_MNT || _fail "mount failed"

 
 echo "+io" > $cgdir/cgroup.subtree_control || _fail "subtree control"
 
 
 echo "+io" > $cgdir/cgroup.subtree_control || _fail "subtree control"