4.5-rc2: Torn write (CRC failure) detected

[Christian Kujau]

I tried to upgrade from 4.4.0-rc5 to 4.5.0-rc2 but I'm currently unable to 
mount my XFS filesystems any more on this PowerPC G4 machine:

# mount -t xfs -o ro /dev/mapper/wdc1 /mnt/disk
mount: mount /dev/mapper/wdc1 on /mnt/disk failed: Bad message

# dmesg | tail
[ 2035.937165] XFS (dm-2): Mounting V4 Filesystem
[ 2036.357198] XFS (dm-2): Torn write (CRC failure) detected at log block 0x296e4. Truncating head block from 0x296e8.
[ 2036.360155] XFS (dm-2): failed to locate log tail
[ 2036.360222] XFS (dm-2): log mount/recovery failed: error -74
[ 2036.360751] XFS (dm-2): log mount failed

AFAICS the message got introduced by "xfs: detect and trim torn writes 
during log recovery" - however, there is no crash involved here. The 
system was running 4.4.0-rc5 just fine and rebooted properly into 
4.5.0-rc2. The underlying storage is an external disk attached via 
Firewire and dm-crypt on top of that.

Running "xfs_repair -n" on the device came back with error code 1 (see 
below for its log[0]).

This is all on Debian/stable with xfs_repair v3.2.1 - but I was unable to 
compile xfsprogs from the current git tree, because of a compilation error[1]

Would it be safe to run xfs_repair without -n on that device?

Christian.

[0] xfs_repair
# file -Ls /dev/mapper/wdc1
/dev/mapper/wdc1: SGI XFS filesystem data (blksz 4096, inosz 256, v2 dirs)

# cryptsetup status wdc1
/dev/mapper/wdc1 is active.
  type:    LUKS1
  cipher:  aes-cbc-essiv:sha256
  keysize: 128 bits
  device:  /dev/sde1
  offset:  1032 sectors
  size:    1953524069 sectors
  mode:    read/write

# time xfs_repair -n /dev/mapper/wdc1; echo $?
Phase 1 - find and verify superblock...
Phase 2 - using internal log
        - scan filesystem freespace and inode maps...
sb_fdblocks 15681968, counted 15731120
        - found root inode chunk
Phase 3 - for each AG...
        - scan (but don't clear) agi unlinked lists...
        - process known inodes and perform inode discovery...
        - agno = 0
        - agno = 1
        - agno = 2
        - agno = 3
        - process newly discovered inodes...
Phase 4 - check for duplicate blocks...
        - setting up duplicate extent list...
        - check for inodes claiming duplicate blocks...
        - agno = 0
        - agno = 1
        - agno = 2
        - agno = 3
No modify flag set, skipping phase 5
Phase 6 - check inode connectivity...
        - traversing filesystem ...
        - traversal finished ...
        - moving disconnected inodes to lost+found ...
Phase 7 - verify link counts...
No modify flag set, skipping filesystem flush and exiting.

real    1m24.829s
user    0m5.012s
sys     0m1.200s
1                                                    == Exit code



[1] xfsprogs/v4.3.0
====================================================
Building io
    [CC]     fiemap.o
In file included from ../include/xfs.h:58:0,
                 from io.h:19,
                 from fiemap.c:24:
../include/xfs/xfs_fs.h:42:8: error: redefinition of ‘struct fsxattr’
 struct fsxattr {
        ^
In file included from fiemap.c:22:0:
/usr/include/linux/fs.h:155:8: note: originally defined here
 struct fsxattr {
        ^
../include/buildrules:59: recipe for target 'fiemap.o' failed
make[2]: *** [fiemap.o] Error 1
include/buildrules:35: recipe for target 'io' failed
make[1]: *** [io] Error 2
Makefile:70: recipe for target 'default' failed
make: *** [default] Error 2
====================================================

And indeed, "struct fsxattr" is already defined in /usr/include/linux/fs.h 
which is provided by linux-libc-dev, which cannot be removed that easily:

$ sudo apt-get purge linux-libc-dev
The following packages will be REMOVED:
build-essential* dh-autoreconf* g++* g++-4.9* libblkid-dev* libbz2-dev* 
libc6-dev* libexpat1-dev* libicu-dev* libmysqlclient-dev* libncurses5-dev* 
libncursesw5-dev* libpam0g-dev* libpcre3-dev* libperl-dev* libpython-dev* 
libpython2.7-dev* libssl-dev* libstdc++-4.9-dev* libtool* libxmlrpc-core-c3-dev*
linux-libc-dev* python-dev* python2.7-dev* uuid-dev* zlib1g-dev*

Note: the compilation error was reported a few days ago on the qemu-devel 
mailing list too:

  [Qemu-devel] qemu fails to build on 4.5-rc1
  https://www.mail-archive.com/qemu-devel@nongnu.org/msg348756.html

-- 
BOFH excuse #154:

You can tune a file system, but you can't tune a fish (from most tunefs man pages)