File xs-21-empty-tdb-database.patch of Package xen.4506

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File xs-21-empty-tdb-database.patch of Package xen.4506

commit 388d3011d1bbc926df61aabd101208d6134d3eb5
Author: Juergen Gross <jgross@suse.com>
Date:   Tue Jan 10 17:13:38 2017 +0100

tools/xenstore: start with empty data base
    
    Today xenstored tries to open a tdb data base file on disk when it is
    started. As this is problematic in most cases the scripts used to start
    xenstored ensure xenstored won't find such a file in order to start
    with an empty xenstore.
    
    A tdb data base file can't be used to restore all Xenstore state as
    e.g. Xenstore watches are not kept in the tdb data base. The file is
    meant to be used for debugging purposes after a xenstored crash only.
    
    Instead of opening a Xenstore data base file found on disk always start
    with an empty data base. This will avoid problems in case someone is
    testing multiple xenstored versions without rebooting (which is not
    supported but helps debugging in some cases).
    
    Signed-off-by: Juergen Gross <jgross@suse.com>
    Acked-by: Wei Liu <wei.liu2@citrix.com>

diff --git a/tools/xenstore/xenstored_core.c b/tools/xenstore/xenstored_core.c
index 3770056..3dc06d4 100644
--- a/tools/xenstore/xenstored_core.c
+++ b/tools/xenstore/xenstored_core.c
@@ -1157,17 +1157,6 @@ static int _rm(struct connection *conn, const void *ctx, struct node *node,
 }
 
 
-static void internal_rm(const char *name)
-{
-	char *tname = talloc_strdup(NULL, name);
-	struct node *node = read_node(NULL, tname, tname);
-	if (node)
-		_rm(NULL, tname, node, tname);
-	talloc_free(node);
-	talloc_free(tname);
-}
-
-
 static int do_rm(struct connection *conn, struct buffered_data *in)
 {
 	struct node *node;
@@ -1582,49 +1571,18 @@ static void setup_structure(void)
 		barf_perror("Could not create tdbname");
 
 	if (!(tdb_flags & TDB_INTERNAL))
-		tdb_ctx = tdb_open_ex(tdbname, 0, tdb_flags, O_RDWR, 0,
-				      &tdb_logger, NULL);
+		unlink(tdbname);
 
-	if (tdb_ctx) {
-		/* XXX When we make xenstored able to restart, this will have
-		   to become cleverer, checking for existing domains and not
-		   removing the corresponding entries, but for now xenstored
-		   cannot be restarted without losing all the registered
-		   watches, which breaks all the backend drivers anyway.  We
-		   can therefore get away with just clearing /local and
-		   expecting Xend to put the appropriate entries back in.
+	tdb_ctx = tdb_open_ex(tdbname, 7919, tdb_flags, O_RDWR|O_CREAT|O_EXCL,
+			      0640, &tdb_logger, NULL);
+	if (!tdb_ctx)
+		barf_perror("Could not create tdb file %s", tdbname);
 
-		   When this change is made it is important to note that
-		   dom0's entries must be cleaned up on reboot _before_ this
-		   daemon starts, otherwise the backend drivers and dom0's
-		   balloon driver will pick up stale entries.  In the case of
-		   the balloon driver, this can be fatal.
-		*/
-		char *tlocal = talloc_strdup(NULL, "/local");
+	manual_node("/", "tool");
+	manual_node("/tool", "xenstored");
+	manual_node("/tool/xenstored", NULL);
 
-		check_store();
-
-		if (remove_local) {
-			internal_rm("/local");
-			create_node(NULL, NULL, tlocal, NULL, 0);
-
-			check_store();
-		}
-
-		talloc_free(tlocal);
-	}
-	else {
-		tdb_ctx = tdb_open_ex(tdbname, 7919, tdb_flags, O_RDWR|O_CREAT,
-				      0640, &tdb_logger, NULL);
-		if (!tdb_ctx)
-			barf_perror("Could not create tdb file %s", tdbname);
-
-		manual_node("/", "tool");
-		manual_node("/tool", "xenstored");
-		manual_node("/tool/xenstored", NULL);
-
-		check_store();
-	}
+	check_store();
 }

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