There is a kernel regression caused by commit 75b470332965 ("btrfs:
raid56: migrate recovery and scrub recovery path to use error_bitmap"),
which leads to scrub not repairing corrupted parity stripes.
So here we add a test case to verify the P/Q stripe scrub behavior by:
- Create a RAID5 or RAID6 btrfs with minimal amount of devices
This means 2 devices for RAID5, and 3 devices for RAID6.
This would result the parity stripe to be a mirror of the only data
stripe.
And since we have control of the content of data stripes, the content
of the P stripe is also fixed.
- Create an 64K file
The file would cover one data stripe.
- Corrupt the P stripe
- Scrub the fs
If scrub is working, the P stripe would be repaired.
Unfortunately scrub can not report any P/Q corruption, limited by its
reporting structure.
So we can not use the return value of scrub to determine if we
repaired anything.
- Verify the content of the P stripe
- Use "btrfs check --check-data-csum" to double check
By above steps, we can verify if the P stripe is properly fixed.
Signed-off-by: Qu Wenruo <wqu@xxxxxxxx>
---
Changelog:
v2:
- Rebase to the latest misc-next
- Use space_cache=v2 mount option instead of nospace_cache
New features like block group tree and extent tree v2 requires v2
cache
- Fix a white space error
---
tests/btrfs/297 | 85 +++++++++++++++++++++++++++++++++++++++++++++
tests/btrfs/297.out | 2 ++
2 files changed, 87 insertions(+)
create mode 100755 tests/btrfs/297
create mode 100644 tests/btrfs/297.out
diff --git a/tests/btrfs/297 b/tests/btrfs/297
new file mode 100755
index 00000000..852c3ace
--- /dev/null
+++ b/tests/btrfs/297
@@ -0,0 +1,85 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2023 YOUR NAME HERE. All Rights Reserved.
+#
+# FS QA Test 297
+#
+# Make sure btrfs scrub can fix parity stripe corruption
+#
+. ./common/preamble
+_begin_fstest auto quick raid scrub
+
+. ./common/filter
+
+_supported_fs btrfs
+_require_odirect
+_require_non_zoned_device "${SCRATCH_DEV}"
+_require_scratch_dev_pool 3
+_fixed_by_kernel_commit 486c737f7fdc \
+ "btrfs: raid56: always verify the P/Q contents for scrub"
+
+workload()
+{
+ local profile=$1
+ local nr_devs=$2
+
+ echo "=== Testing $nr_devs devices $profile ===" >> $seqres.full
+ _scratch_dev_pool_get $nr_devs
+
+ _scratch_pool_mkfs -d $profile -m single >> $seqres.full 2>&1
+ # Use v2 space cache to prevent v1 space cache affecting
+ # the result.
+ _scratch_mount -o space_cache=v2
+
+ # Create one 64K extent which would cover one data stripe.
+ $XFS_IO_PROG -f -d -c "pwrite -S 0xaa -b 64K 0 64K" \
+ "$SCRATCH_MNT/foobar" > /dev/null
+ sync
+
+ # Corrupt the P/Q stripe
+ local logical=$(_btrfs_get_first_logical $SCRATCH_MNT/foobar)
+
+ # The 2nd copy is pointed to P stripe directly.
+ physical_p=$(_btrfs_get_physical ${logical} 2)
+ devpath_p=$(_btrfs_get_device_path ${logical} 2)
+
+ _scratch_unmount
+
+ echo "Corrupt stripe P at devpath $devpath_p physical $physical_p" \
+ >> $seqres.full
+ $XFS_IO_PROG -d -c "pwrite -S 0xff -b 64K $physical_p 64K" $devpath_p \
+ > /dev/null
+
+ # Do a scrub to try repair the P stripe.
+ _scratch_mount -o space_cache=v2
+ $BTRFS_UTIL_PROG scrub start -BdR $SCRATCH_MNT >> $seqres.full 2>&1
+ _scratch_unmount
+
+ # Verify the repaired content directly
+ local output=$($XFS_IO_PROG -c "pread -qv $physical_p 16" $devpath_p | _filter_xfs_io_offset)
+ local expect="XXXXXXXX: aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa ................"
+
+ echo "The first 16 bytes of parity stripe after scrub:" >> $seqres.full
+ echo $output >> $seqres.full
+ if [ "$output" != "$expect" ]; then
+ echo "Unexpected parity content"
+ echo "has:"
+ echo "$output"
+ echo "expect"
+ echo "$expect"
+ fi
+
+ # Last safenet, let btrfs check --check-data-csum to do an offline scrub.
+ $BTRFS_UTIL_PROG check --check-data-csum $SCRATCH_DEV >> $seqres.full 2>&1
+ if [ $? -ne 0 ]; then
+ echo "Error detected after the scrub"
+ fi
+ _scratch_dev_pool_put
+}
+
+workload raid5 2
+workload raid6 3
+
+echo "Silence is golden"
+status=0
+exit
diff --git a/tests/btrfs/297.out b/tests/btrfs/297.out
new file mode 100644
index 00000000..41c373c4
--- /dev/null
+++ b/tests/btrfs/297.out
@@ -0,0 +1,2 @@
+QA output created by 297
+Silence is golden
--
2.41.0
