[RFC][PATCH 13/13] Kemari: use shared region with to flip logdirty_bitmap

[Yoshiaki Tamura <tamura.yoshiaki@lab.ntt.co.jp>]

This is an updated version of the following patch.  No major changes.

http://lists.xensource.com/archives/html/xen-devel/2009-03/msg00382.html

Signed-off-by: Yoshisato Yanagisawa <yanagisawa.yoshisato@lab.ntt.co.jp>
Signed-off-by: Yoshi Tamura <tamura.yoshiaki@lab.ntt.co.jp>
---
 xenstore.c |   30 +++++++++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/xenstore.c b/xenstore.c
index 928e950..4333c79 100644
--- a/xenstore.c
+++ b/xenstore.c
@@ -639,6 +639,8 @@ void xenstore_process_logdirty_event(void)
     static char *active_path = NULL;
     static char *next_active_path = NULL;
     static char *seg = NULL;
+    static char *kemari_qemu_info = NULL;
+    static char *qemu_file = NULL;
     unsigned int len;
     int i;

@@ -705,6 +707,8 @@ void xenstore_process_logdirty_event(void)
             seg = NULL;
             return;
         }
+        kemari_qemu_info = seg + logdirty_bitmap_size * 2;
+        asprintf(&qemu_file, "/dev/shm/qemu-save.%d", domid); /* use tmpfs */
 #endif

         /* Remember the paths for the next-active and active entries */
@@ -722,8 +726,32 @@ void xenstore_process_logdirty_event(void)
         }
     }

+#ifndef CONFIG_STUBDOM
+    if (kemari_enabled) {
+        while (kemari_qemu_info[1])
+            xen_rmb();
+
+        /* Switch buffers */
+        i = kemari_qemu_info[0];
+        if (i != 0 && i != 1) {
+            fprintf(logfile, "Log-dirty: bad next-active entry: %s\n", act);
+            exit(1);
+        }
+        logdirty_bitmap = (unsigned long *)(seg + i * logdirty_bitmap_size);
+        kemari_qemu_info[1] = 1;
+        xen_wmb();
+
+        /* Save QEMU status */
+        while (kemari_qemu_info[2])
+            xen_rmb();
+        do_savevm(qemu_file);
+        kemari_qemu_info[2] = 1;
+        xen_wmb();
+        return;
+    }
+#endif /* !CONFIG_STUBDOM */
     fprintf(logfile, "Triggered log-dirty buffer switch\n");
-
+
     /* Read the required active buffer from the store */
     act = xs_read(xsh, XBT_NULL, next_active_path, &len);
     if (!act) {