Re: [PATCH v5 17/21] libnvdimm: infrastructure for btt devices

[Christoph Hellwig]

On Mon, Jun 01, 2015 at 08:15:41PM -0400, Dan Williams wrote:
> Block devices from an nd bus, in addition to accepting "struct bio"
> based requests, also have the capability to perform byte-aligned
> accesses.  By default only the bio/block interface is used.  However, if
> another driver can make effective use of the byte-aligned capability it
> can claim/disable the block interface and use the byte-aligned "nd_io"
> interface.
> 
> The BTT driver is the initial first consumer of this mechanism to allow
> layering atomic sector update guarantees on top of nd_io capable
> libnvdimm-block-devices, or their partitions.

As mentioned during the last time of the review the layering here
is complete broken.  If you expose additional capabilities from a block
device do it at the block device level.  That is enhance the rw_page
callback to allo byte sized access, add a capability flag on the queue,
etc.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/