block/rnbd: introduce rnbd_access_modes

Add one new array (marked with __maybe_unused to prevent gcc warning about
"defined but not used" with W=1), then we can remove rnbd_access_mode_str
and rnbd-common.c accordingly.

Signed-off-by: Guoqing Jiang <guoqing.jiang@linux.dev>
Acked-by: Jack Wang <jinpu.wang@ionos.com>
Link: https://lore.kernel.org/r/20230524070026.2932-4-guoqing.jiang@linux.dev
Signed-off-by: Jens Axboe <axboe@kernel.dk>

rnbd-srv: remove rnbd_dev_{open,close}

These can be trivially open coded in the callers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Acked-by: Jack Wang <jinpu.wang@ionos.com>
Link: https://lore.kernel.org/r/20220909131509.3263924-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/rnbd-srv: Add event tracing support

Add event tracing mechanism for following routines:
- create_sess()
- destroy_sess()
- process_rdma()
- process_msg_sess_info()
- process_msg_open()
- process_msg_close()

How to use:
1. Load the rnbd_server module
2. cd /sys/kernel/debug/tracing
3. If all the events need to be enabled:
echo 1 > events/rnbd_srv/enable
4. OR only speific routine/event needs to be enabled e.g.
echo 1 > events/rnbd_srv/create_sess/enable
5. cat trace
5. Run some workload which can trigger create_sess() routine/event

Signed-off-by: Santosh Pradhan <santosh.pradhan@ionos.com>
Signed-off-by: Jack Wang <jinpu.wang@ionos.com>
Signed-off-by: Md Haris Iqbal <haris.iqbal@ionos.com>
Link: https://lore.kernel.org/r/20220818105551.110490-2-haris.iqbal@ionos.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/rnbd: include client and server modules into kernel compilation

Add rnbd Makefile, Kconfig and also corresponding lines into upper block
layer files.

Link: https://lore.kernel.org/r/20200511135131.27580-24-danil.kipnis@cloud.ionos.com
Signed-off-by: Danil Kipnis <danil.kipnis@cloud.ionos.com>
Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>