#! /bin/bash
# SPDX-License-Identifier: GPL-2.0
# Copyright (c) 2014 Filipe Manana.  All Rights Reserved.
#
# FS QA Test No. btrfs/050
#
# Regression for btrfs send when an inode only has extended references
# associated to it (no regular references present). This used to cause
# incorrect access to a b+tree leaf, where an extended reference item
# was accessed as if it were a regular reference item, causing unexpected
# and unpredictable behaviour such as producing a random/weird path string
# or a crash.
#
# This issue is fixed by the following linux kernel btrfs patch:
#
#   Btrfs: send, fix incorrect ref access when using extrefs
#
seq=`basename $0`
seqres=$RESULT_DIR/$seq
echo "QA output created by $seq"

tmp=/tmp/$$
status=1	# failure is the default!
trap "_cleanup; exit \$status" 0 1 2 3 15

_cleanup()
{
    rm -fr $send_files_dir
    rm -fr $tmp
}

# get standard environment, filters and checks
. ./common/rc
. ./common/filter

# real QA test starts here
_supported_fs btrfs
_require_test
_require_scratch
_require_fssum

send_files_dir=$TEST_DIR/btrfs-test-$seq

rm -f $seqres.full
rm -fr $send_files_dir
mkdir $send_files_dir

_scratch_mkfs "-O extref" >/dev/null 2>&1
_scratch_mount

# 2550 hard links is enough to cause creation of extended references
# even if the leaf/node size is 64Kb (largest possible).
NUM_LINKS=2550
TEST_PATH=$SCRATCH_MNT/home/john/files/series/qwerty

mkdir -p $TEST_PATH
touch $TEST_PATH/foobar

# Create a bunch of hard links for the file, such that at least one
# inode extended reference item is created.
for i in `seq 1 $NUM_LINKS`; do
	ln $TEST_PATH/foobar $TEST_PATH/foobar_link_`printf "%04d" $i`
done

# The only link we'll have alive at the end.
ln $TEST_PATH/foobar $TEST_PATH/final_foobar_name

# Now delete all previous hard links (except the last one). This will
# remove the regular inode reference item from the b+tree, and will
# leave only an inode extended reference item, which is the condition
# necessary to trigger the bug.
rm -f $TEST_PATH/foobar
for i in `seq 1 $NUM_LINKS`; do
	rm -f $TEST_PATH/foobar_link_`printf "%04d" $i`
done

_run_btrfs_util_prog subvolume snapshot -r $SCRATCH_MNT $SCRATCH_MNT/mysnap1
run_check $FSSUM_PROG -A -f -w $send_files_dir/1.fssum $SCRATCH_MNT/mysnap1
_run_btrfs_util_prog send -f $send_files_dir/1.snap $SCRATCH_MNT/mysnap1

_scratch_unmount
_check_scratch_fs

_scratch_mkfs >/dev/null 2>&1
_scratch_mount

_run_btrfs_util_prog receive -f $send_files_dir/1.snap $SCRATCH_MNT
run_check $FSSUM_PROG -r $send_files_dir/1.fssum $SCRATCH_MNT/mysnap1

status=0
exit