On Mon, May 19, 2008 at 01:32:53PM +0200, Bas van Schaik wrote:
>
> Does this tell you anything?
>
Unfortunately comparing the two dumpe2fs outputs don't show anything
interesting. It did rule out a few cases where e2fsck can silently
mark the filesystem has having been modified (setting the directory
hash hint, moving the journal inode, which it does silently without
informing the user --- and I should fix that one of these days; I'll
create some bug reports to remind myself they need to be fixed), but I
don't see why it happened for your case.
It's definitely not normal; doing a journal replay does not cause fsck
to exit with a non-zero status, if it didn't make any other changes.
I just tested that with e2fsprogs 1.40.8 just in case something had
gotten screwed up, and it worked as expected.
I know how to debug it if you are really motiviated to get to the
bottom of this. It would involve running a modified e2fsck/e2fsprogs
which changes ext2fs_mark_changed() and ext2fs_mark_super_dirty() to
be real functions, and setting breakpoints in gdb so we can trap any
calls made to those functions and dump out a stack backtrace, and then
continuing the e2fsck run, and then reporting to me the stack
backtraces where gdb trapped calls to ext2fs_mark_changed() and/or
ext2fs_mark_super_dirty().
Andreas is right though that if you are taking a proper snapshot, the
disk really should be quiesced and no journal replay should be
required at all. That's how a devicemapper snapshot works in LVM ---
so one good question to explore is how *are* you doing your snapshots.
- Ted
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