Re: [PATCH v4 0/3] convert write_threads, write_version and write_ports to netlink commands

[Jeff Layton <jlayton@kernel.org>]

On Sat, 2023-11-04 at 12:13 +0100, Lorenzo Bianconi wrote:
> Introduce write_threads, write_version and write_ports netlink
> commands similar to the ones available through the procfs.
> 
> Changes since v3:
> - drop write_maxconn and write_maxblksize for the moment
> - add write_version and write_ports commands
> Changes since v2:
> - use u32 to store nthreads in nfsd_nl_threads_set_doit
> - rename server-attr in control-plane in nfsd.yaml specs
> Changes since v1:
> - remove write_v4_end_grace command
> - add write_maxblksize and write_maxconn netlink commands
> 
> This patch can be tested with user-space tool reported below:
> https://github.com/LorenzoBianconi/nfsd-netlink.git
> This series is based on the commit below available in net-next tree
> 
> commit e0fadcffdd172d3a762cb3d0e2e185b8198532d9
> Author: Jakub Kicinski <kuba@kernel.org>
> Date:   Fri Oct 6 06:50:32 2023 -0700
> 
>     tools: ynl-gen: handle do ops with no input attrs
> 
>     The code supports dumps with no input attributes currently
>     thru a combination of special-casing and luck.
>     Clean up the handling of ops with no inputs. Create empty
>     Structs, and skip printing of empty types.
>     This makes dos with no inputs work.
> 
> Lorenzo Bianconi (3):
>   NFSD: convert write_threads to netlink commands
>   NFSD: convert write_version to netlink commands
>   NFSD: convert write_ports to netlink commands
> 
>  Documentation/netlink/specs/nfsd.yaml |  83 ++++++++
>  fs/nfsd/netlink.c                     |  54 ++++++
>  fs/nfsd/netlink.h                     |   8 +
>  fs/nfsd/nfsctl.c                      | 267 +++++++++++++++++++++++++-
>  include/uapi/linux/nfsd_netlink.h     |  30 +++
>  tools/net/ynl/generated/nfsd-user.c   | 254 ++++++++++++++++++++++++
>  tools/net/ynl/generated/nfsd-user.h   | 156 +++++++++++++++
>  7 files changed, 845 insertions(+), 7 deletions(-)
> 

Nice work, Lorenzo! Now comes the bikeshedding...

With the nfsdfs interface, we sort of had to split things up into
multiple files like this, but it has some drawbacks, in particular with
weird behavior when people do things out of order.

Would it make more sense to instead have a single netlink command that
sets up ports and versions, and then spawns the requisite amount of
threads, all in one fell swoop?

That does presuppose we can send down a variable-length frame though,
but I assume that is possible with netlink.
-- 
Jeff Layton <jlayton@kernel.org>