On Thu, 2016-06-23 at 17:05 -0400, Mike Snitzer wrote:
:
> +static int device_supports_dax(struct dm_target *ti, struct dm_dev *dev,
> + sector_t start, sector_t len, void *data)
> +{
> + struct request_queue *q = bdev_get_queue(dev->bdev);
> +
> + return q && blk_queue_dax(q);
> +}
> +
> +static bool dm_table_supports_dax(struct dm_table *t)
> +{
> + struct dm_target *ti;
> + unsigned i = 0;
> +
> + /* Ensure that all targets support DAX. */
> + while (i < dm_table_get_num_targets(t)) {
> + ti = dm_table_get_target(t, i++);
> +
> + if (!ti->type->direct_access)
> + return false;
> +
> + if (!ti->type->iterate_devices ||
> + !ti->type->iterate_devices(ti, device_supports_dax,
> NULL))
> + return false;
> + }
> +
> + return true;
> +}
> +
Hi Mike,
Thanks for the update. I have a question about the above change. Targets may
have their own parameters. For instance, dm-stripe has 'chunk_size', which is
checked in stripe_ctr(). DAX adds additional restriction that chunk_size
needs to be aligned by page size. So, I think we need to keep target
responsible to verify if DAX can be supported. What do you think?
Thanks,
-Toshi
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