[Ocfs2-devel] [PATCH 1/1] Ocfs2: Add a mount option "coherency=*" to handle cluster coherency for O_DIRECT writes.

[Joel Becker]

On Mon, Oct 11, 2010 at 04:46:39PM +0800, Tristan Ye wrote:
> Currently, default behavior of O_DIRECT writes was allowing
> concurrent writing among nodes, no cluster coherency guaranteed
> (no EX locks was taken), it hurts buffered reads on other nodes
> by reading stale data from cache.
> 
> The new mount option introduce a chance to choose two different
> behaviors for O_DIRECT writes:
> 
>     * coherency=full, as the default value, will disallow
>                       concurrent O_DIRECT writes by taking
>                       EX locks.
> 
>     * coherency=buffered, allow concurrent O_DIRECT writes
>                           without EX lock among nodes, which
>                           gains high performance at risk of
>                           getting stale data on other nodes.
> 
> Signed-off-by: Tristan Ye <tristan.ye at oracle.com>

	This patch is now in the merge-window branch of ocfs2.git.

Joel

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	"Be kinder than necessary."

Joel Becker
Consulting Software Developer
Oracle
E-mail: joel.becker at oracle.com
Phone: (650) 506-8127