lockd: drop inappropriate svc_get() from locked_get()

[ Upstream commit 665e89ab

 ]

The below-mentioned patch was intended to simplify refcounting on the
svc_serv used by locked.  The goal was to only ever have a single
reference from the single thread.  To that end we dropped a call to
lockd_start_svc() (except when creating thread) which would take a
reference, and dropped the svc_put(serv) that would drop that reference.

Unfortunately we didn't also remove the svc_get() from
lockd_create_svc() in the case where the svc_serv already existed.
So after the patch:
 - on the first call the svc_serv was allocated and the one reference
   was given to the thread, so there are no extra references
 - on subsequent calls svc_get() was called so there is now an extra
   reference.
This is clearly not consistent.

The inconsistency is also clear in the current code in lockd_get()
takes *two* references, one on nlmsvc_serv and one by incrementing
nlmsvc_users.   This clearly does not match lockd_put().

So: drop that svc_get() from lockd_get() (which used to be in
lockd_create_svc().

Reported-by: Ido Schimmel <idosch@idosch.org>
Closes: https://lore.kernel.org/linux-nfs/ZHsI%2FH16VX9kJQX1@shredder/T/#u
Fixes: b73a2972

 ("lockd: move lockd_start_svc() call into lockd_create_svc()")
Signed-off-by: NeilBrown <neilb@suse.de>
Tested-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>