[Ocfs2-tools-devel] [PATCH] ocfs2_journal_check_available_features(): Never allow FEATURE_COMPAT_CHECKSUM

[Sunil Mushran]

Acked-by: Sunil Mushran <sunil.mushran at oracle.com>


Joel Becker wrote:
> ocfs2 will never use jbd2 checksums.  If a jbd2 checksum fails, the
> transaction is not replayed.  This means that some parts of the
> transaction may have checkpointed while other parts have not.  This
> inconsistent state requires fsck to repair.  ocfs2, being clustered,
> can't tolerate that situation.  Instead, ocfs2 prefers to replay the
> journal.  This allows the cluster to remain running.  Using the METAECC
> feature allows ocfs2 to detect and isolate any corrupted blocks.
>
> Signed-off-by: Joel Becker <joel.becker at oracle.com>
> ---
>  libocfs2/mkjournal.c |   13 +++++++++++++
>  1 files changed, 13 insertions(+), 0 deletions(-)
>
> diff --git a/libocfs2/mkjournal.c b/libocfs2/mkjournal.c
> index 8575c40..cb0e2ee 100644
> --- a/libocfs2/mkjournal.c
> +++ b/libocfs2/mkjournal.c
> @@ -62,6 +62,19 @@ static int ocfs2_journal_check_available_features(journal_superblock_t *jsb,
>  	    features->opt_compat)
>  		return 0;
>  
> +	/*
> +	 * ocfs2 will never use jbd2 checksums.  If a jbd2 checksum fails,
> +	 * the transaction is not replayed.  This means that some parts of
> +	 * the transaction may have checkpointed while other parts have not.
> +	 * This inconsistent state requires fsck to repair.  ocfs2, being
> +	 * clustered, can't tolerate that situation.  Instead, ocfs2
> +	 * prefers to replay the journal.  This allows the cluster to
> +	 * remain running.  Using the METAECC feature allows ocfs2 to
> +	 * detect and isolate any corrupted blocks.
> +	 */
> +	if (features->opt_compat & JBD2_FEATURE_COMPAT_CHECKSUM)
> +		return 0;
> +
>  	if ((features->opt_ro_compat & JBD2_KNOWN_ROCOMPAT_FEATURES) !=
>  	    features->opt_ro_compat)
>  		return 0;
>