io_uring: don't take fs for recvmsg/sendmsg

We don't even allow not plain data msg_control, which is disallowed in
__sys_{send,revb}msg_sock(). So no need in fs for IORING_OP_SENDMSG and
IORING_OP_RECVMSG. fs->lock is less contanged not as much as before, but
there are cases that can be, e.g. IOSQE_ASYNC.
Signed-off-by: NPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -852,8 +852,7 @@ static const struct io_op_def io_op_defs[] = {
 		.pollout		= 1,
 		.needs_async_data	= 1,
 		.async_size		= sizeof(struct io_async_msghdr),
-		.work_flags		= IO_WQ_WORK_MM | IO_WQ_WORK_BLKCG |
-						IO_WQ_WORK_FS,
+		.work_flags		= IO_WQ_WORK_MM | IO_WQ_WORK_BLKCG,
 	},
 	[IORING_OP_RECVMSG] = {
 		.needs_file		= 1,
@@ -862,8 +861,7 @@ static const struct io_op_def io_op_defs[] = {
 		.buffer_select		= 1,
 		.needs_async_data	= 1,
 		.async_size		= sizeof(struct io_async_msghdr),
-		.work_flags		= IO_WQ_WORK_MM | IO_WQ_WORK_BLKCG |
-						IO_WQ_WORK_FS,
+		.work_flags		= IO_WQ_WORK_MM | IO_WQ_WORK_BLKCG,
 	},
 	[IORING_OP_TIMEOUT] = {
 		.needs_async_data	= 1,