Change the semantics of GetDomainPath so that it always succeeds, regardless of

whether a domain has been introduced to the store.  Added a separate message
XS_IS_DOMAIN_INTRODUCED and API for that (xs_is_domain_introduced) to determine
whether the domain has really been introduced.  This change means that the
tools can determine the correct domain path earlier in the domain creation
process, which is particularly a factor with live migration, as it allows us
to create the devices earlier in the process, and unpause the new domain before
performing the introduce.  Until recently we already had these features, but
the simplification of the interface between xend and xenstored caused breakage.

No longer clear out the domain path when a domain is introduced -- this was a
hack to work around the recent problematic semantics of GetDomainPath.

Do not write the contents of the info block to the store.  All the configuration
info is written to the /vm path, and anything else in the info block is either
dealt with explicitly or is ephemeral and has no place in the store.

Signed-off-by: Ewan Mellor <ewan@xensource.com>

1 files changed, 27 insertions, 12 deletions

diff --git a/tools/xenstore/xenstored_domain.c b/tools/xenstore/xenstored_domain.c
index 69e429ccfa..d252469617 100644
--- a/tools/xenstore/xenstored_domain.c
+++ b/tools/xenstore/xenstored_domain.c
@@ -250,6 +250,11 @@ bool domain_can_write(struct connection *conn)
 	return ((intf->rsp_prod - intf->rsp_cons) != XENSTORE_RING_SIZE);
 }
 
+static char *talloc_domain_path(void *context, unsigned int domid)
+{
+	return talloc_asprintf(context, "/local/domain/%u", domid);
+}
+
 static struct domain *new_domain(void *context, unsigned int domid,
 				 unsigned long mfn, int port)
 {
@@ -262,7 +267,7 @@ static struct domain *new_domain(void *context, unsigned int domid,
 	domain->port = 0;
 	domain->shutdown = 0;
 	domain->domid = domid;
-	domain->path = talloc_asprintf(domain, "/local/domain/%d", domid);
+	domain->path = talloc_domain_path(domain, domid);
 	domain->interface = xc_map_foreign_range(
 		*xc_handle, domain->domid,
 		getpagesize(), PROT_READ|PROT_WRITE, mfn);
@@ -272,8 +277,6 @@ static struct domain *new_domain(void *context, unsigned int domid,
 	list_add(&domain->list, &domains);
 	talloc_set_destructor(domain, destroy_domain);
 
-	internal_rm(domain->path);
-
 	/* Tell kernel we're interested in this event. */
         bind.remote_domain = domid;
         bind.remote_port   = port;
@@ -403,25 +406,37 @@ void do_release(struct connection *conn, const char *domid_str)
 
 void do_get_domain_path(struct connection *conn, const char *domid_str)
 {
-	struct domain *domain;
-	unsigned int domid;
+	char *path;
 
 	if (!domid_str) {
 		send_error(conn, EINVAL);
 		return;
 	}
 
+	path = talloc_domain_path(conn, atoi(domid_str));
+
+	send_reply(conn, XS_GET_DOMAIN_PATH, path, strlen(path) + 1);
+
+	talloc_free(path);
+}
+
+void do_is_domain_introduced(struct connection *conn, const char *domid_str)
+{
+	int result;
+	unsigned int domid;
+
+        if (!domid_str) {
+                send_error(conn, EINVAL);
+                return;
+        }
+
 	domid = atoi(domid_str);
 	if (domid == DOMID_SELF)
-		domain = conn->domain;
+		result = 1;
 	else
-		domain = find_domain_by_domid(domid);
+		result = (find_domain_by_domid(domid) != NULL);
 
-	if (!domain)
-		send_error(conn, ENOENT);
-	else
-		send_reply(conn, XS_GET_DOMAIN_PATH, domain->path,
-			   strlen(domain->path) + 1);
+	send_reply(conn, XS_IS_DOMAIN_INTRODUCED, result ? "T" : "F", 2);
 }
 
 static int close_xc_handle(void *_handle)