apfstests/tests/btrfs/105

#! /bin/bash
# FS QA Test No. btrfs/105
#
# Test that an incremental send works after a file from the parent snapshot
# gets replaced in the send snapshot by another one at the same exact location,
# with the same name and with the same inode number.
#
#-----------------------------------------------------------------------
# Copyright (C) 2015 SUSE Linux Products GmbH. All Rights Reserved.
# Author: Filipe Manana <fdmanana@suse.com>
# Copyright (C) 2015 Martin Raiber <martin@urbackup.org>
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License as
# published by the Free Software Foundation.
#
# This program is distributed in the hope that it would be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write the Free Software Foundation,
# Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
#-----------------------------------------------------------------------
#

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()
{
	cd /
	rm -fr $send_files_dir
	rm -f $tmp.*
}

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

# real QA test starts here
_supported_fs btrfs
_supported_os Linux
_require_scratch

send_files_dir=$TEST_DIR/btrfs-test-$seq

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

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

# Create our test file with a single extent of 64K.
mkdir -p $SCRATCH_MNT/foo
$XFS_IO_PROG -f -c "pwrite -S 0xaa 0 64K" $SCRATCH_MNT/foo/bar | _filter_xfs_io

_run_btrfs_util_prog subvolume snapshot -r $SCRATCH_MNT $SCRATCH_MNT/mysnap1
_run_btrfs_util_prog subvolume snapshot $SCRATCH_MNT $SCRATCH_MNT/mysnap2

echo "File digest before being replaced:"
md5sum $SCRATCH_MNT/mysnap1/foo/bar | _filter_scratch

# Remove the file and then create a new one in the same location with the same
# name but with different content. This new file ends up getting the same inode
# number as the previous one, because that inode number was the highest inode
# number used by the snapshot's root and therefore when attempting to find the
# a new inode number for the new file, we end up reusing the same inode number.
# This happens because currently btrfs uses the highest inode number summed by 1
# for the first inode created once a snapshot's root is loaded (done at
# fs/btrfs/inode-map.c:btrfs_find_free_objectid in the linux kernel tree).
# Having these two different files in the snapshots with the same inode number
# (but different generation numbers) caused the btrfs send code to emit an
# incorrect path for the file when issuing an unlink operation because it failed
# to realize they were different files.
rm -f $SCRATCH_MNT/mysnap2/foo/bar
$XFS_IO_PROG -f -c "pwrite -S 0xbb 0 96K" \
	$SCRATCH_MNT/mysnap2/foo/bar | _filter_xfs_io

_run_btrfs_util_prog subvolume snapshot -r $SCRATCH_MNT/mysnap2 \
	$SCRATCH_MNT/mysnap2_ro

_run_btrfs_util_prog send $SCRATCH_MNT/mysnap1 -f $send_files_dir/1.snap
_run_btrfs_util_prog send -p $SCRATCH_MNT/mysnap1 $SCRATCH_MNT/mysnap2_ro \
	-f $send_files_dir/2.snap

echo "File digest in the original filesystem after being replaced:"
md5sum $SCRATCH_MNT/mysnap2_ro/foo/bar | _filter_scratch

# Now recreate the filesystem by receiving both send streams and verify we get
# the same file contents that the original filesystem had.
_scratch_unmount
_scratch_mkfs >>$seqres.full 2>&1
_scratch_mount

_run_btrfs_util_prog receive $SCRATCH_MNT -f $send_files_dir/1.snap
_run_btrfs_util_prog receive $SCRATCH_MNT -f $send_files_dir/2.snap

echo "File digest in the new filesystem:"
# Must match the digest from the new file.
md5sum $SCRATCH_MNT/mysnap2_ro/foo/bar | _filter_scratch

status=0
exit