On 2020-03-28 01:29, Christoph Hellwig wrote:

On Fri, Mar 27, 2020 at 08:58:09PM -0700, Bart Van Assche wrote:

quoted

On 2020-03-20 05:16, Jack Wang wrote:

quoted

To avoid duplicate code in rnbd-srv, we need to reexport
bio_map_kern.

NAK.  If you need this helper you are doing something wrong.  What is
the use case where a simple bio_add_page loop won't work?

Hi Christoph,

There are more users in the Linux kernel of bio_add_pc_page() than only
bio_map_kern(), e.g. the SCSI target pass-through code
(drivers/target/target_core_pscsi.c). The code that uses bio_map_kern()
is in patch 22/26: "block/rnbd: server: functionality for IO submission
to file or block dev". Isn't that use case similar to the SCSI
pass-through code? I think the RNBD server code also implements storage
target functionality.

Thanks,

Bart.