From: Filipe Manana <fdmanana@xxxxxxxx>
Test that defragging files with very small sizes works and does not
result in any crash, hang or corruption.
This is motivated by a regression introduced in kernel 5.16 where
attempting to defrag a file with a size of 1 byte would result in
the kernel code hitting an "infinite" loop (iterating from 0 to
(u64)-1 in increments of 256K, which in practice is an eternity).
The regression is fixed by a patch with the following subject:
"btrfs: fix too long loop when defragging a 1 byte file"
Signed-off-by: Filipe Manana <fdmanana@xxxxxxxx>
---
tests/btrfs/255 | 64 +++++++++++++++++++++++++++++++++++++++++++++
tests/btrfs/255.out | 3 +++
2 files changed, 67 insertions(+)
create mode 100755 tests/btrfs/255
create mode 100644 tests/btrfs/255.out
diff --git a/tests/btrfs/255 b/tests/btrfs/255
new file mode 100755
index 00000000..55b11145
--- /dev/null
+++ b/tests/btrfs/255
@@ -0,0 +1,64 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (C) 2022 SUSE Linux Products GmbH. All Rights Reserved.
+#
+# FS QA Test No. 255
+#
+# Test that defragging files with very small sizes works and does not result in
+# any crash, hang or corruption.
+#
+. ./common/preamble
+_begin_fstest auto quick defrag
+
+_cleanup()
+{
+ cd /
+ rm -r -f $tmp.*
+}
+
+# Import common functions.
+. ./common/filter
+
+# real QA test starts here
+
+_supported_fs btrfs
+_require_scratch
+_require_fssum
+
+_scratch_mkfs >> $seqres.full 2>&1
+_scratch_mount
+
+checksums_file="$TEST_DIR/btrfs-test-$seq-checksums"
+block_size=$(_get_block_size "$SCRATCH_MNT")
+
+# Test file sizes of 0, 1, 512, 1K, 2K, 4K, 8K, 16K, 32K and 64K bytes.
+file_sizes=( 0 1 512 1024 2048 4096 8192 16384 32768 65536 )
+
+# Create the files and compute their checksums.
+for sz in ${file_sizes[@]}; do
+ byte=$(printf "0x%x" $((RANDOM % 255)))
+ $XFS_IO_PROG -f -c "pwrite -S $byte 0 $sz" "$SCRATCH_MNT/f_$sz" >> $seqres.full
+done
+
+# Compute the checksums.
+$FSSUM_PROG -A -f -w "$checksums_file" "$SCRATCH_MNT"
+
+# Now defrag each file.
+for sz in ${file_sizes[@]}; do
+ echo "Defragging file with $sz bytes..." >> $seqres.full
+ $BTRFS_UTIL_PROG filesystem defragment "$SCRATCH_MNT/f_$sz"
+done
+
+# Verify the checksums after the defrag operations.
+$FSSUM_PROG -r "$checksums_file" "$SCRATCH_MNT"
+
+# Unmount and mount again, this clears the page cache and we want to see that
+# no corruptions were persisted.
+_scratch_cycle_mount
+
+# Verify the checksums again.
+$FSSUM_PROG -r "$checksums_file" "$SCRATCH_MNT"
+
+# success, all done
+status=0
+exit
diff --git a/tests/btrfs/255.out b/tests/btrfs/255.out
new file mode 100644
index 00000000..9b1db997
--- /dev/null
+++ b/tests/btrfs/255.out
@@ -0,0 +1,3 @@
+QA output created by 255
+OK
+OK
--
2.33.0
