BTRFS: Testing restore of file compressed with lzo falied

Problem Description
===================================
Using xfstests, testing btrfs/041 testcase which does btrfs-restore operation .

Analysis : This testcase create extents, write data to it, compress it then restore.But it is failing with lzo compression.

root@powerkvm5:~/xfstests# ./check btrfs/041
FSTYP -- btrfs
PLATFORM -- Linux/ppc64le powerkvm5 4.4.0-13-generic
MKFS_OPTIONS -- /dev/sdg2
MOUNT_OPTIONS -- /dev/sdg2 /mnt/scratch

btrfs/041 [failed, exit status 1] - output mismatch (see /root/xfstests/results//btrfs/041.out.bad)
    --- tests/btrfs/041.out 2016-03-15 01:28:12.782520209 -0500
    +++ /root/xfstests/results//btrfs/041.out.bad 2016-03-18 02:47:17.598581773 -0500
    @@ -11,30 +11,5 @@
     wrote 100/100 bytes at offset 99000
     XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
     67edd038aaa42adb5a1aa78f2eb1d2b6 SCRATCH_MNT/foo
    -67edd038aaa42adb5a1aa78f2eb1d2b6
    -Testing restore of file compressed with zlib
    -wrote 100000/100000 bytes at offset 0
    -XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
    ...
    (Run 'diff -u tests/btrfs/041.out /root/xfstests/results//btrfs/041.out.bad' to see the entire diff)
Ran: btrfs/041
Failures: btrfs/041
Failed 1 of 1 tests

System : powerkvm5, Bare metal
OS : Ubuntu 16.04
Version : 4.4.0-13-generic

root@powerkvm5:~/xfstests# cat /root/xfstests/results//btrfs/041.out.bad
QA output created by 041
Testing restore of file compressed with lzo
wrote 100000/100000 bytes at offset 0
XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
wrote 100000/100000 bytes at offset 100000
XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
wrote 2/2 bytes at offset 10000
XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
wrote 11/11 bytes at offset 33000
XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
wrote 100/100 bytes at offset 99000
XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
67edd038aaa42adb5a1aa78f2eb1d2b6 SCRATCH_MNT/foo
failed: '/bin/btrfs restore /dev/sdg2 /mnt/test/btrfs-test-041'
(see /root/xfstests/results//btrfs/041.full for details)
root@powerkvm5:~/xfstests# vi tests/btrfs/041
root@powerkvm5:~/xfstests# uname -a
Linux powerkvm5 4.4.0-13-generic #29-Ubuntu SMP Fri Mar 11 19:30:44 UTC 2016 ppc64le ppc64le ppc64le GNU/Linux

Steps to reproduce :
======================================
1. Install xfstests.
2. Create 5 file images of 10gb each, using dd command
3. Create loop devices using above images
4. Create btrfs fs on these loop devices
5. test setup:
1. suites has already built with 2 directories : xfsprogs & xfstests
2. create /mnt/test and /mnt/scratch directories
3. cd xfstests and edit local.config file
sample file for btrfs test :

export TEST_DEV=/dev/loop0
export TEST_DIR=/mnt/test
export SCRATCH_DEV_POOL="/dev/loop1 /dev/loop2 /dev/loop3 /dev/loop4"
export SCRATCH_MNT=/mnt/scratch

6. create fsgqa user : 'useradd fsgqa'
7. ./check btrfs/041

== Comment: #2 - Chandan B. Rajendra <email address hidden> - 2016-03-18 09:07:07 ==
The issue was recently fixed by Fiona. Please refer to the commit b025392ffca98b3a74947cf8f772535cf8bfceb3 in the git repository available at git://repo.or.cz/btrfs-progs-unstable/devel.git.

b025392ffca98b3a74947cf8f772535cf8bfceb3
Author: Feifei Xu <email address hidden>
AuthorDate: Thu Mar 10 16:43:20 2016 +0800
Commit: David Sterba <email address hidden>
CommitDate: Mon Mar 14 13:42:47 2016 +0100

btrfs-progs: Replace hardcoded PAGE_CACHE_SIZE with sectorsize.

PAGE_CACHE_SIZE is hardcoded to 4K in cmds-restore.c. Correct
value should be sector size. Fix this through replacing
hardcoded 4K to sectorsize.

Signed-off-by: Feifei Xu <email address hidden>
Signed-off-by: David Sterba <email address hidden>

We should mirror this bug to Canonical and request them to apply the commit to their btrfs-progs package.