io_uring: One wqe per wq

io_uring: One wqe per wq

Right now io_wq allocates one io_wqe per NUMA node.  As io_wq is now
bound to a task, the task basically uses only the NUMA local io_wqe, and
almost never changes NUMA nodes, thus, the other wqes are mostly
unused.

Allocate just one io_wqe embedded into io_wq, and uses all possible cpus
(cpu_possible_mask) in the io_wqe->cpumask.

Signed-off-by: Breno Leitao <leitao@debian.org>
Link: https://lore.kernel.org/r/20230310201107.4020580-1-leitao@debian.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>