tests/btrfs/303

#! /bin/bash
# SPDX-License-Identifier: GPL-2.0
# Copyright (C) 2024 SUSE Linux Products GmbH. All Rights Reserved.
#
# FS QA Test 303
#
# Test that an incremental send does not issue unnecessary writes for a sparse
# file that got one new extent between its previous extent and the file's size.
#
. ./common/preamble
_begin_fstest auto quick snapshot send fiemap

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

. ./common/filter
. ./common/punch  # for _filter_fiemap

_require_test
_require_scratch
_require_xfs_io_command "fiemap"

_fixed_by_kernel_commit 5897710b28ca \
	"btrfs: send: don't issue unnecessary zero writes for trailing hole"

send_files_dir=$TEST_DIR/btrfs-test-$seq

rm -fr $send_files_dir
mkdir $send_files_dir

_scratch_mkfs >> $seqres.full 2>&1 || _fail "mkfs failed"
_scratch_mount

$XFS_IO_PROG -f -c "truncate 1G" $SCRATCH_MNT/foobar

# Now create the base snapshot, which is going to be the parent snapshot for
# a later incremental send.
$BTRFS_UTIL_PROG subvolume snapshot -r $SCRATCH_MNT \
		 $SCRATCH_MNT/mysnap1 > /dev/null

# Create send stream (full send) for the first snapshot.
$BTRFS_UTIL_PROG send -f $send_files_dir/1.snap \
		 $SCRATCH_MNT/mysnap1 2>&1 1>/dev/null | _filter_scratch

# Now write one extent at the beginning of the file and one somewhere in the
# middle, leaving a gap between the end of this second extent and the file's
# size.
$XFS_IO_PROG -c "pwrite -S 0xab -b 64K 0 64K" \
	     -c "pwrite -S 0xcd -b 64K 512M 64K" \
	     $SCRATCH_MNT/foobar | _filter_xfs_io

# Now create a second snapshot which is going to be used for an incremental
# send operation.
$BTRFS_UTIL_PROG subvolume snapshot -r $SCRATCH_MNT \
		 $SCRATCH_MNT/mysnap2 > /dev/null

# Create send stream (incremental send) for the second snapshot.
$BTRFS_UTIL_PROG send -p $SCRATCH_MNT/mysnap1 -f $send_files_dir/2.snap \
		 $SCRATCH_MNT/mysnap2 2>&1 1>/dev/null | _filter_scratch

# Now recreate the filesystem by receiving both send streams and verify we get
# the same content that the original filesystem had and file foobar has only two
# extents with a size of 64K each.
_scratch_unmount
_scratch_mkfs >> $seqres.full 2>&1 || _fail "mkfs failed"
_scratch_mount

$BTRFS_UTIL_PROG receive -f $send_files_dir/1.snap $SCRATCH_MNT > /dev/null
$BTRFS_UTIL_PROG receive -f $send_files_dir/2.snap $SCRATCH_MNT > /dev/null

echo "File content in the new filesystem:"
_hexdump $SCRATCH_MNT/mysnap2/foobar

echo "File fiemap in the new filesystem:"
# Should have:
#
# 64K extent at file range [0, 64K[
# hole at file range [64K, 512M[
# 64K extent at file range [512M, 512M + 64K[
# hole at file range [512M + 64K, 1G[
$XFS_IO_PROG -r -c "fiemap -v" $SCRATCH_MNT/mysnap2/foobar | _filter_fiemap

# File should be using only 128K of data (two 64K extents).
echo "Space used by the file: $(du -h $SCRATCH_MNT/mysnap2/foobar | cut -f 1)"

status=0
exit