[PATCH 00/10] improve smbdirect_mr_io lifetime

[Steve French]

merged into cifs-2.6.git for-next pending more testing

On Sun, Oct 12, 2025 at 2:10 PM Stefan Metzmacher <metze at samba.org> wrote:
>
> Hi,
>
> these patches improve and simplify our handling of
> smbdirect_mr_io structures and their lifetime.
>
> smbd_register_mr() returns a pointer to struct smbdirect_mr_io
> and smbd_deregister_mr() gives the pointer back.
>
> But currently the memory itself is managed by the connection
> (struct smbdirect_socket) and smbd_destroy() has a strange
> wait loop in order to wait for smbd_deregister_mr() being
> called. It means code in smbd_destroy() is aware of
> the server mutex in the generic smb client handling above
> the transport layer.
>
> These patches do some cleanups and fixes before changing
> the logic to use a kref and a mutex in order to allow
> smbd_deregister_mr() being called after smbd_destroy()
> as the memory of smbdirect_mr_io will stay in memory
> but will be detached from the connection.
>
> This makes the code independent of cifs_server_[un]lock()
> and will allow us to move more smbdirect code into common
> functions (shared between client and server).
>
> I think these should go into 6.18.
>
> Stefan Metzmacher (10):
>   smb: smbdirect: introduce smbdirect_mr_io.{kref,mutex} and
>     SMBDIRECT_MR_DISABLED
>   smb: client: change smbd_deregister_mr() to return void
>   smb: client: let destroy_mr_list() call list_del(&mr->list)
>   smb: client: let destroy_mr_list() remove locked from the list
>   smb: client: improve logic in allocate_mr_list()
>   smb: client: improve logic in smbd_register_mr()
>   smb: client: improve logic in smbd_deregister_mr()
>   smb: client: call ib_dma_unmap_sg if mr->sgt.nents is not 0
>   smb: client: let destroy_mr_list() call ib_dereg_mr() before
>     ib_dma_unmap_sg()
>   smb: client: let destroy_mr_list() keep smbdirect_mr_io memory if
>     registered
>
>  fs/smb/client/smbdirect.c                  | 312 ++++++++++++++-------
>  fs/smb/client/smbdirect.h                  |   2 +-
>  fs/smb/common/smbdirect/smbdirect_socket.h |  11 +-
>  3 files changed, 224 insertions(+), 101 deletions(-)
>
> --
> 2.43.0
>


-- 
Thanks,

Steve