Comment 0 for bug 1438032

== Comment: #0 - ABDUL HALEEM <email address hidden> - 2015-02-13 01:50:18 ==
*** Problem description ***
btrfs/060 test of xfstests segfaults with unhandled signal 11 at 00003fff88820000 nip 0000000010065ac0 lr 0000000010065b18 code 30001 messages in dmesg.

*** uname output ***
Linux ubuntu 3.18.0-13-generic #14-Ubuntu SMP Fri Feb 6 09:57:41 UTC 2015 ppc64le ppc64le ppc64le GNU/Linux

*** Steps to reproduce ***
1. Power8 Machine installed Ubuntu 15.04 on a PowerVM LPAR.
2. Download git://oss.sgi.com/xfs/cmds/xfstests.git , compile and build
3. create 6 loop devices with btrfs file system on it.
4. local.config file will look like this:
export TEST_DEV=/dev/loop0
export TEST_DIR=/mnt/test
export SCRATCH_DEV_POOL="/dev/loop1 /dev/loop2 /dev/loop3 /dev/loop4 /dev/loop5"
export SCRATCH_MNT=/mnt/scratch

5. run the test : ./check btrfs/060
6. test failed with errors in dmesg and the command btrfsck core dumped.

root@ubuntu:~/xfstests# cat /root/xfstests/results/btrfs/060.out.bad
QA output created by 060
Silence is golden
./common/rc: line 1932: 3378 Segmentation fault btrfsck $device > $tmp.fsck 2>&1
_check_btrfs_filesystem: filesystem on /dev/loop1 is inconsistent (see /root/xfstests/results//btrfs/060.full)

Core file, tests logs and syslogs are attached.

dmesg logs:
[ 717.146506] BTRFS info (device loop5): disk space caching is enabled
[ 717.150413] BTRFS: creating UUID tree
[ 717.939847] BTRFS info (device loop5): relocating block group 1676083200 flags 9
[ 720.914279] BTRFS info (device loop5): relocating block group 37683200 flags 12
[ 723.476025] BTRFS info (device loop5): found 7 extents
[ 725.093216] BTRFS info (device loop5): relocating block group 20971520 flags 10
[ 726.615751] BTRFS info (device loop5): found 1 extents
[ 727.151299] BTRFS info (device loop5): relocating block group 12582912 flags 1
[ 727.808751] BTRFS info (device loop5): relocating block group 4194304 flags 4
[ 728.294908] BTRFS info (device loop5): relocating block group 0 flags 2
[ 728.780977] BTRFS info (device loop5): found 1 extents
[ 730.204584] btrfsck[3378]: unhandled signal 11 at 00003fff88820000 nip 0000000010065ac0 lr 0000000010065b18 code 30001
[ 1483.937916] btrfsck[3640]: unhandled signal 11 at 00003fffaa030000 nip 0000000010065ac0 lr 0000000010065b18 code 30001
[ 1525.291669] btrfsck[3644]: unhandled signal 11 at 00003fffaf300000 nip 0000000010065ac0 lr 0000000010065b18 code 30001

Thanks

== Comment: #5 - Chandan B. Rajendra <email address hidden> - 2015-02-18 10:11:23 ==
The following upstream commit will fix the issue:

2c0e02a568c7db99922e9080407f8fc22d1991bd
Author: David Sterba <email address hidden>
Date: Wed May 28 11:25:24 2014 +0200

    btrfs-progs: make free space checker work on non-4k sectorsize filesystems

    The value of sector for space cache was hardcoded to 4k, and used to
    calculate bitmap sizes. In kernel, the BITS_PER_BITMAP is derived from
    PAGE_CACHE_SIZE which is not available for userspace, that can also deal
    with filesystem of varying sectorsize.

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

Without this patch, In io_ctl_check_crc(), we end up passing an incorrect "length" value to the crc32c_le() function.

The patch (2c0e02a568c7db99922e9080407f8fc22d1991bd) needs to picked to help resolve this issue on Ubuntu.