#! /bin/bash
# SPDX-License-Identifier: GPL-2.0
# Copyright (C) 2015 SUSE Linux Products GmbH. All Rights Reserved.
#
# FSQA Test No. 106
#
# Regression test for file read corruption when using compressed extents
# that represent file ranges with a length that is a multiple of 16 pages
# and that are shared by multiple consecutive ranges of the same file.
#
. ./common/preamble
_begin_fstest auto quick clone compress

. ./common/filter

_supported_fs btrfs
_require_scratch
_require_cloner

test_clone_and_read_compressed_extent()
{
	local mount_opts=$1

	_scratch_mkfs >>$seqres.full 2>&1
	_scratch_mount $mount_opts

	PAGE_SIZE=$(_get_page_size)

	# Create our test file with 16 pages worth of data in a single extent
	# that is going to be compressed no matter which compression algorithm
	# is used (zlib/lzo).
	$XFS_IO_PROG -f -c "pwrite -S 0xaa 0K $((16 * $PAGE_SIZE))" \
		     $SCRATCH_MNT/foo | _filter_xfs_io_pages_modified

	# Now clone the compressed extent into an adjacent file offset.
	$CLONER_PROG -s 0 -d $((16 * $PAGE_SIZE)) -l $((16 * $PAGE_SIZE)) \
		$SCRATCH_MNT/foo $SCRATCH_MNT/foo

	echo "Hash before unmount:" >> $seqres.full
	old_md5=$(_md5_checksum "$SCRATCH_MNT/foo")
	echo "$old_md5" >> $seqres.full

	# Remount the fs or clear the page cache to trigger the bug in btrfs.
	# Because the extent has an uncompressed length that is a multiple of 16
	# pages, all the pages belonging to the second range of the file that is
	# mapped by the page index range [16, 31], which points to the same
	# extent as the first file range mapped by the page index range [0, 15],
	# had their contents full of zeroes instead of the byte 0xaa. This was a
	# bug exclusively in the read path of compressed extents, the correct
	# data was stored on disk, btrfs just failed to fill in the pages
	# correctly.
	_scratch_cycle_mount

	echo "Hash after remount:" >> $seqres.full
	# Must match the digest we got before.
	new_md5=$(_md5_checksum "$SCRATCH_MNT/foo")
	echo "$new_md5" >> $seqres.full
	if [ "$old_md5" != "$new_md5" ]; then
		echo "Hash mismatches after remount"
	else
		echo "Hash matches after remount"
	fi
}

echo -e "\nTesting with zlib compression..."
test_clone_and_read_compressed_extent "-o compress=zlib"

_scratch_unmount

echo -e "\nTesting with lzo compression..."
test_clone_and_read_compressed_extent "-o compress=lzo"

status=0
exit