On Wed, Aug 31 2016 at 6:18pm -0400,
Bart Van Assche <bart.vanassche@xxxxxxxxxxx> wrote:
> If pg_init_retries is set and a request is queued against a
> multipath device with all underlying block devices in the "dying"
> state then an infinite loop is triggered because activate_path()
> never succeeds and hence never calls pg_init_done(). Fix this by
> making ql_select_path() skip dying paths.
>
> Signed-off-by: Bart Van Assche <bart.vanassche@xxxxxxxxxxx>
Assuming DM multipath needs to be sprinkling these dying queue checks so
deep (which I'm not yet sold on):
Same would be needed in service-time and round-robin right?
> ---
> drivers/md/dm-queue-length.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/md/dm-queue-length.c b/drivers/md/dm-queue-length.c
> index 23f1786..a283c66 100644
> --- a/drivers/md/dm-queue-length.c
> +++ b/drivers/md/dm-queue-length.c
> @@ -199,11 +199,12 @@ static struct dm_path *ql_select_path(struct path_selector *ps, size_t nr_bytes)
> list_move_tail(s->valid_paths.next, &s->valid_paths);
>
> list_for_each_entry(pi, &s->valid_paths, list) {
> - if (!best ||
> - (atomic_read(&pi->qlen) < atomic_read(&best->qlen)))
> + if ((!best ||
> + atomic_read(&pi->qlen) < atomic_read(&best->qlen)) &&
> + !blk_queue_dying(pi->path->dev->bdev->bd_queue))
> best = pi;
>
> - if (!atomic_read(&best->qlen))
> + if (best && atomic_read(&best->qlen) == 0)
> break;
> }
>
> --
> 2.9.3
>
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