Calculate VIRTQUEUE_NUM in "net/9p/trans_virtio.c" from stack size

[Guan Xin <guanx.bac@xxxxxxxxx>]

For HPC applications the hard-coded VIRTQUEUE_NUM of 128 seems to
limit the throughput of guest systems accessing cluster filesystems
mounted on the host.

Just increase VIRTQUEUE_NUM for kernels with a
larger stack.

Author: GUAN Xin <guanx.bac@xxxxxxxxx>
Signed-off-by: GUAN Xin <guanx.bac@xxxxxxxxx>
cc: Eric Van Hensbergen <ericvh@xxxxxxxxxx>
cc: v9fs@xxxxxxxxxxxxxxx
cc: netdev@xxxxxxxxxxxxxxx
cc: linux-fsdevel@xxxxxxxxxxxxxxx

--- net/9p/trans_virtio.c.orig  2024-10-25 10:25:09.390922517 +0800
+++ net/9p/trans_virtio.c       2024-10-25 16:48:40.451680192 +0800
@@ -31,11 +31,12 @@
#include <net/9p/transport.h>
#include <linux/scatterlist.h>
#include <linux/swap.h>
+#include <linux/thread_info.h>
#include <linux/virtio.h>
#include <linux/virtio_9p.h>
#include "trans_common.h"

-#define VIRTQUEUE_NUM  128
+#define VIRTQUEUE_NUM  (1 << (THREAD_SIZE_ORDER + PAGE_SHIFT - 6))

/* a single mutex to manage channel initialization and attachment */
static DEFINE_MUTEX(virtio_9p_lock);