RDMA/rtrs-clt: Use this_cpu_ API for stats

Use this_cpu_x() for increasing/adding a percpu counter through a
percpu pointer without the need to disable/enable preemption.

Link: https://lore.kernel.org/r/20220712103113.617754-3-haris.iqbal@ionos.com
Suggested-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Santosh Kumar Pradhan <santosh.pradhan@ionos.com>
Signed-off-by: Jack Wang <jinpu.wang@ionos.com>
Signed-off-by: Md Haris Iqbal <haris.iqbal@ionos.com>
Acked-by: Guoqing Jiang <guoqing.jiang@linux.dev>
Reviewed-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>

RDMA/rtrs-clt: Rename rtrs_clt_sess to rtrs_clt_path

rtrs_clt_sess is used for paths and not sessions on the client side. This
creates confusion so let's rename it to rtrs_clt_path. Also, rename
related variables and functions.

Coccinelle is used to do the transformations for most of the occurrences
and remaining ones were handled manually.

Link: https://lore.kernel.org/r/20220105180708.7774-4-jinpu.wang@ionos.com
Signed-off-by: Vaishali Thakkar <vaishali.thakkar@ionos.com>
Signed-off-by: Jack Wang <jinpu.wang@ionos.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

RDMA/rtrs: Rename rtrs_sess to rtrs_path

rtrs_sess is in fact a path. This makes it confusing and difficult to get
into the code. So let's rename the structure and related use cases of it.

Coccinelle was used to do the transformation for most of the occurrences
and remaining ones were handled manually.

Link: https://lore.kernel.org/r/20220105180708.7774-2-jinpu.wang@ionos.com
Signed-off-by: Vaishali Thakkar <vaishali.thakkar@ionos.com>
Signed-off-by: Jack Wang <jinpu.wang@ionos.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

RDMA/rtrs: Call {get,put}_cpu_ptr to silence a debug kernel warning

With preemption enabled (CONFIG_DEBUG_PREEMPT=y), the following appeared
when rnbd client tries to map remote block device.

BUG: using smp_processor_id() in preemptible [00000000] code: bash/1733
caller is debug_smp_processor_id+0x17/0x20
CPU: 0 PID: 1733 Comm: bash Not tainted 5.16.0-rc1 #5
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.14.0-0-g155821a-rebuilt.opensuse.org 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0x5d/0x78
dump_stack+0x10/0x12
check_preemption_disabled+0xe4/0xf0
debug_smp_processor_id+0x17/0x20
rtrs_clt_update_all_stats+0x3b/0x70 [rtrs_client]
rtrs_clt_read_req+0xc3/0x380 [rtrs_client]
? rtrs_clt_init_req+0xe3/0x120 [rtrs_client]
rtrs_clt_request+0x1a7/0x320 [rtrs_client]
? 0xffffffffc0ab1000
send_usr_msg+0xbf/0x160 [rnbd_client]
? rnbd_clt_put_sess+0x60/0x60 [rnbd_client]
? send_usr_msg+0x160/0x160 [rnbd_client]
? sg_alloc_table+0x27/0xb0
? sg_zero_buffer+0xd0/0xd0
send_msg_sess_info+0xe9/0x180 [rnbd_client]
? rnbd_clt_put_sess+0x60/0x60 [rnbd_client]
? blk_mq_alloc_tag_set+0x2ef/0x370
rnbd_clt_map_device+0xba8/0xcd0 [rnbd_client]
? send_msg_open+0x200/0x200 [rnbd_client]
rnbd_clt_map_device_store+0x3e5/0x620 [rnbd_client

To supress the calltrace, let's call get_cpu_ptr/put_cpu_ptr pair in
rtrs_clt_update_rdma_stats to disable preemption when accessing per-cpu
variable.

While at it, let's make the similar change in rtrs_clt_update_wc_stats.
And for rtrs_clt_inc_failover_cnt, though it was only called inside rcu
section, but it still can be preempted in case CONFIG_PREEMPT_RCU is
enabled, so change it to {get,put}_cpu_ptr pair either.

Link: https://lore.kernel.org/r/20211128133501.38710-1-guoqing.jiang@linux.dev
Signed-off-by: Guoqing Jiang <guoqing.jiang@linux.dev>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

RDMA/rtrs-clt: Follow "one entry one value" rule for IO migration stats

This commit divides the sysfs entry cpu_migration into 2 different entries
One for "from cpus" and the other for "to cpus".

Link: https://lore.kernel.org/r/20210922125333.351454-8-haris.iqbal@ionos.com
Signed-off-by: Md Haris Iqbal <haris.iqbal@ionos.com>
Reviewed-by: Gioh Kim <gi-oh.kim@ionos.com>
Reviewed-by: Aleksei Marov <aleksei.marov@ionos.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

RDMA/rtrs: Remove len parameter from helper print functions of sysfs

Since we have changed all sysfs show functions to use sysfs_emit, we do
not require the len (PAGE_SIZE) in our helper print functions. So remove
it from the function parameter.

Link: https://lore.kernel.org/r/20210922125333.351454-3-haris.iqbal@ionos.com
Signed-off-by: Md Haris Iqbal <haris.iqbal@ionos.com>
Signed-off-by: Jack Wang <jinpu.wang@ionos.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

RDMA/rtrs: Use sysfs_emit instead of s*printf function for sysfs show

sysfs_emit function was added to be aware of the PAGE_SIZE maximum of the
temporary buffer used for outputting sysfs content, so there is no
possible overruns. So replace the uses of any s*printf functions for the
sysfs show functions with sysfs_emit.

Link: https://lore.kernel.org/r/20210922125333.351454-2-haris.iqbal@ionos.com
Signed-off-by: Md Haris Iqbal <haris.iqbal@ionos.com>
Signed-off-by: Jack Wang <jinpu.wang@ionos.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

RDMA/rtrs-clt: Fix counting inflight IO

There are mis-match at counting inflight IO after changing the multipath
policy.

For example, we started fio test with round-robin policy and then we
changed the policy to min-inflight. IOs created under the RR policy is
finished under the min-inflight policy and inflight counter only
decreased. So the counter would be negative value. And also we started
fio test with min-inflight policy and changed the policy to the
round-robin. IOs created under the min-inflight policy increased the
inflight IO counter but the inflight IO counter was not decreased because
the policy was the round-robin when IO was finished.

So it should count IOs only if the IO is created under the min-inflight
policy. It should not care the policy when the IO is finished.

This patch adds a field mp_policy in struct rtrs_clt_io_req and stores the
multipath policy when an object of rtrs_clt_io_req is created. Then
rtrs-clt checks the mp_policy of only struct rtrs_clt_io_req instead of
the struct rtrs_clt.

Link: https://lore.kernel.org/r/20210806112112.124313-6-haris.iqbal@ionos.com
Signed-off-by: Gioh Kim <gi-oh.kim@ionos.com>
Signed-off-by: Jack Wang <jinpu.wang@ionos.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Md Haris Iqbal <haris.iqbal@ionos.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

RDMA/rtrs: Remove all likely and unlikely

The IO performance test with fio after swapping the likely and unlikely
macros in all if-statement shows no difference. They do not help for the
performance of rtrs.

Thanks to Haakon Bugge for the test scenario.

The fio test did random read on 32 rnbd devices and 64 processes.
Test environment:
- Intel(R) Xeon(R) Gold 6130 CPU @ 2.10GHz
- 376G memory
- kernel version: 5.4.86
- gcc version: gcc (Debian 8.3.0-6) 8.3.0
- Infiniband controller: Mellanox Technologies MT27800 Family [ConnectX-5]

Test result:
- before swapping: IOPS=829k, BW=3239MiB/s
- after swapping: IOPS=829k, BW=3238MiB/s
- remove all (un)likely: IOPS=829k, BW=3238MiB/s

Link: https://lore.kernel.org/r/20210806112112.124313-5-haris.iqbal@ionos.com
Signed-off-by: Gioh Kim <gi-oh.kim@ionos.com>
Signed-off-by: Jack Wang <jinpu.wang@ionos.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Md Haris Iqbal <haris.iqbal@ionos.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

RDMA/rtrs: client: statistics functions

This introduces set of functions used on client side to account statistics
of RDMA data sent/received, amount of IOs inflight, latency, cpu
migrations, etc. Almost all statistics are collected using percpu
variables.

Link: https://lore.kernel.org/r/20200511135131.27580-8-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>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>