[Filesystems-devel] Bug#788185: squashfs-tools: Occasional corruption of large files.

Andreas Krüger andreas.krueger at famsik.de
Tue Jun 9 07:58:05 UTC 2015


Package: squashfs-tools
Version: 1:4.2+20130409-2
Severity: normal

Hello,

I'm using squashfs for full backups of my laptop, from a (quiet)
LVM snapshot. I run sha256sum checksums on each file, then run

    mksquashfs /freeze /backup/$timestamp.backup.squashfs \
      -always-use-fragments -processors 2

then mount the resulting squashfs file system and compare the checksums.

Over the years, I've seen checksum errors occasionally.

I have recently started to use virtual machines, so I now have more
very large files in my backup.  Since then, the number of problems
seemed to have increased substantially

The current backup saw two of these.  Interestingly, in both
cases, the problem is very close to the end of the file.  For the
record: In either case, the file length, according to ls -l, is
the same for the original and the copy in the squashfs.

One file is 2776104960 bytes long, a plain "cmp" run finds the
first inconsistency at byte 2776018945, a mere 86015 bytes from
the end.

The other file is 7831814144 bytes long, a plain "cmp" finds the
first inconsistency at byte 7831683073, a mere 131071 bytes from
the end.

Regards, and thank you for providing fine software

Andreas


-- System Information:
Debian Release: 8.1
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 3.16.0-4-amd64 (SMP w/4 CPU cores)
Locale: LANG=de_DE.UTF-8, LC_CTYPE=de_DE.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages squashfs-tools depends on:
ii  libc6      2.19-18
ii  liblzma5   5.1.1alpha+20120614-2+b3
ii  liblzo2-2  2.08-1.2
ii  zlib1g     1:1.2.8.dfsg-2+b1

squashfs-tools recommends no packages.

squashfs-tools suggests no packages.

-- no debconf information


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