Re: [Ocfs2-devel] [PATCH v3] ocfs2/journal: fix umount hang after flushing journal failure

[Eric Ren]

On 01/13/2017 10:52 AM, Changwei Ge wrote:
> Hi Joseph,
>
> Do you think my last version of patch to fix umount hang after journal
> flushing failure is OK?
>
> If so, I 'd like to ask Andrew's help to merge this patch into his test
> tree.
>
>
> Thanks,
>
> Br.
>
> Changwei

The message above should not occur in a formal patch.  It should be put in "cover-letter" if
you want to say something to the other developers. See "git format-patch --cover-letter".

>  From 686b52ee2f06395c53e36e2c7515c276dc7541fb Mon Sep 17 00:00:00 2001
> From: Changwei Ge <ge.changwei@xxxxxxx>
> Date: Wed, 11 Jan 2017 09:05:35 +0800
> Subject: [PATCH] fix umount hang after journal flushing failure

The commit message is needed here! It should describe what's your problem, how to reproduce it,
and what's your solution, things like that.

> Signed-off-by: Changwei Ge <ge.changwei@xxxxxxx>
> ---
>   fs/ocfs2/journal.c |   18 ++++++++++++++++++
>   1 file changed, 18 insertions(+)
>
> diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c
> index a244f14..5f3c862 100644
> --- a/fs/ocfs2/journal.c
> +++ b/fs/ocfs2/journal.c
> @@ -2315,6 +2315,24 @@ static int ocfs2_commit_thread(void *arg)
>                               "commit_thread: %u transactions pending on "
>                               "shutdown\n",
>                               atomic_read(&journal->j_num_trans));
> +
> +                       if (status < 0) {
> +                               mlog(ML_ERROR, "journal is already abort
> and cannot be "
> +                                        "flushed any more. So ignore
> the pending "
> +                                        "transactions to avoid blocking
> ocfs2 unmount.\n");

Can you find any example in the kernel source to print out message like that?!

I saw Joseph showed you the right way in previous email:
"

if (status < 0) {

     mlog(ML_ERROR, "journal is already abort and cannot be "

             "flushed any more. So ignore the pending "

             "transactions to avoid blocking ocfs2 unmount.\n");

"
So, please be careful and learn from the kernel source and the right way other developers do in
their patch work. Otherwise, it's meaningless to waste others' time in such basic issues.

> +                               /*
> +                                * This may a litte hacky, however, no
> chance
> +                                * for ocfs2/journal to decrease this
> variable
> +                                * thourgh commit-thread. I have to do so to
> +                                * avoid umount hang after journal flushing
> +                                * failure. Since jounral has been
> marked ABORT
> +                                * within jbd2_journal_flush, commit
> cache will
> +                                * never do any real work to flush
> journal to
> +                                * disk.Set it to ZERO so that umount will
> +                                * continue during shutting down journal
> +                                */
> +                               atomic_set(&journal->j_num_trans, 0);
It's possible to corrupt data doing this way. Why not just crash the kernel when jbd2 aborts?
and let the other node to do the journal recovery. It's the strength of cluster filesystem.

Anyway, it's glad to see you guys making contributions!

Thanks,
Eric


> +                       }
>                  }
>          }
>
> --
> 1.7.9.5
>
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