ping?
On Tue, Aug 02, 2016 at 02:36:32PM +0200, Christoph Hellwig wrote:
> From: Hannes Reinecke <hare@xxxxxxx>
>
> If dm-mpath encounters an reservation conflict it should not fail the
> path (as communication with the target is not affected) but should
> rather retry on another path. However, in doing so we might be inducing
> a ping-pong between paths, with no guarantee of any forward progress.
>
> And arguably a reservation conflict is an unexpected error, so we should
> be passing it upwards to allow the application to take appropriate steps.
>
> Signed-off-by: Hannes Reinecke <hare@xxxxxxx>
> Acked-by: Christoph Hellwig <hch@xxxxxx>
> Tested-by: Christoph Hellwig <hch@xxxxxx>
> ---
> drivers/md/dm-mpath.c | 14 ++++++++++----
> 1 file changed, 10 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
> index 7eac080..8d2f916 100644
> --- a/drivers/md/dm-mpath.c
> +++ b/drivers/md/dm-mpath.c
> @@ -1555,16 +1555,22 @@ static int do_end_io(struct multipath *m, struct request *clone,
> if (noretry_error(error))
> return error;
>
> - if (mpio->pgpath)
> + /*
> + * EBADE signals an reservation conflict.
> + * We shouldn't fail the path here as we can communicate with
> + * the target. We should failover to the next path, but in
> + * doing so we might be causing a ping-pong between paths.
> + * So just return the reservation conflict error.
> + */
> + if (error == -EBADE)
> + r = error;
> + else if (mpio->pgpath)
> fail_path(mpio->pgpath);
>
> if (!atomic_read(&m->nr_valid_paths)) {
> if (!test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
> if (!must_push_back_rq(m))
> r = -EIO;
> - } else {
> - if (error == -EBADE)
> - r = error;
> }
> }
>
> --
> 2.1.4
>
> --
> dm-devel mailing list
> dm-devel@xxxxxxxxxx
> https://www.redhat.com/mailman/listinfo/dm-devel
---end quoted text---
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