io_uring: don't quiesce intial files register

There is no reason why we would want to fully quiesce ring on
IORING_REGISTER_FILES, if it's already registered we fail.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/563bb8060bb2d3efbc32fce6101678281c574d2a.1617287883.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -9815,6 +9815,7 @@ static int io_register_enable_rings(struct io_ring_ctx *ctx)
 static bool io_register_op_must_quiesce(int op)
 {
 	switch (op) {
+	case IORING_REGISTER_FILES:
 	case IORING_UNREGISTER_FILES:
 	case IORING_REGISTER_FILES_UPDATE:
 	case IORING_REGISTER_PROBE: