#! /bin/bash
# SPDX-License-Identifier: GPL-2.0
# Copyright (c) 2015 Red Hat, Inc. All Rights Reserved.
#
# FS QA Test 074-extsz-hints-vs-maxextlen
#
# Check some extent size hint boundary conditions that can result in
# MAXEXTLEN overflows.
#
# In xfs_bmap_extsize_align(), we had,
# 	if ((temp = (align_alen % extsz))) {
# 		align_alen += extsz - temp;
# 	}
# align_alen had the value of 2097151 (i.e. MAXEXTLEN) blocks. extsz had
# the value of 4096 blocks.
#
# align_alen % extsz will be 4095. so align_alen will end up having
# 2097151 + (4096 - 4095) = 2097152 i.e. (MAXEXTLEN + 1). Thus the length
# of the new extent will be larger than MAXEXTLEN. This will later cause
# the bmbt leaf to have an entry whose length is set to zero block count.
#
. ./common/preamble
_begin_fstest quick auto prealloc rw

# Override the default cleanup function.
_cleanup()
{
	cd /
	[ -n "$loop_dev" ] &&_destroy_loop_device $loop_dev
	rm -f $tmp.* $LOOP_FILE
}

# Import common functions.
. ./common/filter


_require_test
_require_xfs_io_command "falloc"

# we use loop devices for this so that we can create large files for prealloc
# without having to care about the underlying device size.
_require_loop

LOOP_FILE=$TEST_DIR/$seq.img
LOOP_MNT=$TEST_DIR/$seq.mnt
mkdir -p $LOOP_MNT
$XFS_IO_PROG -ft -c "truncate 1t" $LOOP_FILE >> $seqres.full
loop_dev=`_create_loop_device $LOOP_FILE`

_mkfs_dev -d size=260g,agcount=2 $loop_dev
_mount $loop_dev $LOOP_MNT

BLOCK_SIZE=$(_get_file_block_size $LOOP_MNT)

# Corrupt the BMBT by creating extents larger than MAXEXTLEN
# For 4k blocksize, MAXEXTLEN * 4k = 2097151 * 4k = 8589930496 = ~8GiB
$XFS_IO_PROG -ft \
	-c "extsize $(($BLOCK_SIZE * 4096))" \
	-c "falloc 0 $(($BLOCK_SIZE * 2097152))" \
	$LOOP_MNT/foo >> $seqres.full

_unmount $LOOP_MNT
_check_xfs_filesystem $loop_dev none none

_mkfs_dev -f $loop_dev
_mount $loop_dev $LOOP_MNT

# check we trim both ends of the extent approproiately; this will fail
# on 1k block size filesystems without the correct fixes in place.
$XFS_IO_PROG -ft \
	-c "extsize 1g" \
	-c "falloc 1023m 2g" \
	$LOOP_MNT/foo >> $seqres.full

_unmount $LOOP_MNT
_check_xfs_filesystem $loop_dev none none

_destroy_loop_device $loop_dev
unset loop_dev

# success, all done
echo "Silence is golden"
status=0
exit
