#! /bin/bash
# SPDX-License-Identifier: GPL-2.0
# Copyright (C) 2021 SUSE Linux Products GmbH. All Rights Reserved.
#
# FS QA Test No. btrfs/241
#
# Test that an incremental send operation succeeds, and produces the correct
# results, after renaming and moving around directories and files with multiple
# hardlinks, in such a way that one of the files gets the old name and location
# of a directory and another name (hardlink) with the old name and location of
# another file that was located in that same directory.
#
. ./common/preamble
_begin_fstest auto quick send

# Override the default cleanup function.
_cleanup()
{
	cd /
	rm -fr $send_files_dir
	rm -f $tmp.*
}

. ./common/filter

_supported_fs btrfs
_require_test
_require_scratch
_require_fssum

send_files_dir=$TEST_DIR/btrfs-test-$seq

rm -fr $send_files_dir
mkdir $send_files_dir

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

# Create our test files and directory. Inode 259 (file3) has two hard links.
touch $SCRATCH_MNT/file1
touch $SCRATCH_MNT/file2
touch $SCRATCH_MNT/file3

mkdir $SCRATCH_MNT/A
ln $SCRATCH_MNT/file3 $SCRATCH_MNT/A/hard_link

# Filesystem looks like:
#
# .                                     (ino 256)
# |----- file1                          (ino 257)
# |----- file2                          (ino 258)
# |----- file3                          (ino 259)
# |----- A/                             (ino 260)
#        |---- hard_link                (ino 259)
#

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

$BTRFS_UTIL_PROG send -f $send_files_dir/1.snap \
	$SCRATCH_MNT/mysnap1 2>&1 1>/dev/null | _filter_scratch

# Move inode 257 into directory inode 260. This results in computing the path
# for inode 260 as "/A" and caching it.
mv $SCRATCH_MNT/file1 $SCRATCH_MNT/A/file1

# Move inode 258 (file2) into directory inode 260, with a name of "hard_link",
# moving first inode 259 away since it currently has that location and name.
mv $SCRATCH_MNT/A/hard_link $SCRATCH_MNT/tmp
mv $SCRATCH_MNT/file2 $SCRATCH_MNT/A/hard_link

# Now rename inode 260 to something else (B for example) and then create a hard
# link for inode 258 that has the old name and location of inode 260 ("/A").
mv $SCRATCH_MNT/A $SCRATCH_MNT/B
ln $SCRATCH_MNT/B/hard_link $SCRATCH_MNT/A

# Filesystem now looks like:
#
# .                                     (ino 256)
# |----- tmp                            (ino 259)
# |----- file3                          (ino 259)
# |----- B/                             (ino 260)
# |      |---- file1                    (ino 257)
# |      |---- hard_link                (ino 258)
# |
# |----- A                              (ino 258)

# Create another snapshot of our subvolume and use it for an incremental send.
$BTRFS_UTIL_PROG subvolume snapshot -r $SCRATCH_MNT \
		 $SCRATCH_MNT/mysnap2 > /dev/null
$BTRFS_UTIL_PROG send -p $SCRATCH_MNT/mysnap1 -f $send_files_dir/2.snap \
		 $SCRATCH_MNT/mysnap2 2>&1 1>/dev/null | _filter_scratch

$FSSUM_PROG -A -f -w $send_files_dir/1.fssum $SCRATCH_MNT/mysnap1
$FSSUM_PROG -A -f -w $send_files_dir/2.fssum \
	-x $SCRATCH_MNT/mysnap2/mysnap1 $SCRATCH_MNT/mysnap2

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

# First add the first snapshot to the new filesystem by applying the first send
# stream.
$BTRFS_UTIL_PROG receive -f $send_files_dir/1.snap $SCRATCH_MNT > /dev/null

# The incremental receive operation below used to fail with the following error:
#
#    ERROR: unlink A/hard_link failed: No such file or directory
#
# This is because when send is processing inode 257, it generates the path for
# inode 260 as "/A", since that inode is its parent in the send snapshot, and
# caches that path.
#
# Later when processing inode 258, it first processes its new reference that has
# the path of "/A", which results in orphanizing inode 260 because there is a
# a path collision. This results in issuing a rename operation from "/A" to
# "/o260-6-0".
#
# Finally when processing the new reference "B/hard_link" for inode 258, it
# notices that it collides with inode 259 (not yet processed, because it has a
# higher inode number), since that inode has the name "hard_link" under the
# directory inode 260. It also checks that inode 259 has two hardlinks, so it
# decides to issue a unlink operation for the name "hard_link" for inode 259.
# However the path passed to the unlink operation is "/A/hard_link", which is
# incorrect since currently "/A" does not exists, due to the orphanization of
# inode 260 mentioned before. The path is incorrect because it was computed and
# cached before the orphanization. This results in the receiver to fail with the
# above error.
#
$BTRFS_UTIL_PROG receive -f $send_files_dir/2.snap $SCRATCH_MNT > /dev/null

$FSSUM_PROG -r $send_files_dir/1.fssum $SCRATCH_MNT/mysnap1
$FSSUM_PROG -r $send_files_dir/2.fssum $SCRATCH_MNT/mysnap2

status=0
exit