io_uring: add missing IORING_MAP_OFF_ZCRX_REGION in io_uring_mmap

Allow user to mmap the kernel allocated zerocopy-rx refill queue.

Signed-off-by: Bui Quang Minh <minhquangbui99@gmail.com>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: Li Zetao <lizetao1@huawei.com>
Link: https://lore.kernel.org/r/20250221085933.26034-1-minhquangbui99@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring/memmap.c

@@ -271,6 +271,8 @@ static struct io_mapped_region *io_mmap_get_region(struct io_ring_ctx *ctx,
 		return io_pbuf_get_region(ctx, bgid);
 	case IORING_MAP_OFF_PARAM_REGION:
 		return &ctx->param_region;
+	case IORING_MAP_OFF_ZCRX_REGION:
+		return &ctx->zcrx_region;
 	}
 	return NULL;
 }