Re: [Xen-devel] [PATCH] make qemu handle drbd properly

[Jim Fehlig <jfehlig@xxxxxxxxxx>]

Ian Jackson wrote:
> James Harper writes ("[Xen-devel] [PATCH] make qemu handle drbd properly"):
>   
>> This attached patch allows qemu to accept a drbd: prefix and interpret
>> it as a drbd resource. It then searches for it in /dev/drbd/by-res/
>> (which must be mapped via udev). It's against 4.0-testing.
>>     
>
> Jim, did any of your drbd tests involve HVM domains ?
>   

No, they did not :(.

But we have a similar hack (err, patch - attached for reference) for
other external block scripts that we support. Interestingly, drbd is
missing from the patch. I stumbled across this patch several months ago,
but the original author is gone and I have not had time to consider a
solution that will accommodate arbitrary external block scripts.

Jim


Index: xen-4.0.1-testing/tools/ioemu-qemu-xen/xenstore.c
===================================================================
--- xen-4.0.1-testing.orig/tools/ioemu-qemu-xen/xenstore.c
+++ xen-4.0.1-testing/tools/ioemu-qemu-xen/xenstore.c
@@ -399,7 +399,7 @@ void xenstore_parse_domain_config(int hv
     char *buf = NULL;
     char *fpath = NULL, *bpath = NULL, *btype = NULL,
         *dev = NULL, *params = NULL, *drv = NULL;
-    int i, ret, is_tap;
+    int i, j, ret, is_tap;
     unsigned int len, num, hd_index, pci_devid = 0;
     BlockDriverState *bs;
     BlockDriver *format;
@@ -491,12 +491,7 @@ void xenstore_parse_domain_config(int hv
             continue;
         free(danger_type);
         danger_type = xs_read(xsh, XBT_NULL, danger_buf, &len);
-        if (pasprintf(&buf, "%s/params", bpath) == -1)
-            continue;
-        free(params);
-        params = xs_read(xsh, XBT_NULL, buf, &len);
-        if (params == NULL)
-            continue;
+
         /* read the name of the device */
         if (pasprintf(&buf, "%s/type", bpath) == -1)
             continue;
@@ -504,6 +499,35 @@ void xenstore_parse_domain_config(int hv
         drv = xs_read(xsh, XBT_NULL, buf, &len);
         if (drv == NULL)
             continue;
+
+        free(params);
+        if (!strcmp(drv,"iscsi") || !strcmp(drv, "npiv") ||
+            !strcmp(drv,"dmmd")) {
+          if (pasprintf(&buf, "%s/node", bpath) == -1)
+             continue;
+
+          /* wait for block-[iscsi|npiv|dmmd] script to complete and populate 
the
+           * node entry.  try 30 times (30 secs) */
+          for (j = 0; j < 30; j++) {
+            params = xs_read(xsh, XBT_NULL, buf, &len);
+            if (params != NULL)
+               break;
+           sleep(1);
+          }
+          if (params == NULL) {
+             fprintf(stderr, "qemu: %s device not found -- timed out \n", drv);
+            continue;
+          }
+        }
+        else
+        {
+          if (pasprintf(&buf, "%s/params", bpath) == -1)
+              continue;
+           params = xs_read(xsh, XBT_NULL, buf, &len);
+           if (params == NULL)
+             continue;
+        }
+
         /* Obtain blktap sub-type prefix */
         if (!strcmp(drv, "tap") && params[0]) {
             char *offset = strchr(params, ':'); 

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