ceph: fully initialize new layout

When we are setting a new layout, fully initialize the structure:
 - zero it out
 - always set preferred_osd to -1
Signed-off-by: Sage Weil <sage@inktank.com>
Reviewed-by: Alex Elder <elder@inktank.com>

fs/ceph/ioctl.c

@@ -80,22 +80,29 @@ static long ceph_ioctl_set_layout(struct file *file, void __user *arg)
 
 	/* validate changed params against current layout */
 	err = ceph_do_getattr(file->f_dentry->d_inode, CEPH_STAT_CAP_LAYOUT);
-	if (!err) {
-		nl.stripe_unit = ceph_file_layout_su(ci->i_layout);
-		nl.stripe_count = ceph_file_layout_stripe_count(ci->i_layout);
-		nl.object_size = ceph_file_layout_object_size(ci->i_layout);
-		nl.data_pool = le32_to_cpu(ci->i_layout.fl_pg_pool);
-	} else
+	if (err)
 		return err;
 
+	memset(&nl, 0, sizeof(nl));
 	if (l.stripe_count)
 		nl.stripe_count = l.stripe_count;
+	else
+		nl.stripe_count = ceph_file_layout_stripe_count(ci->i_layout);
 	if (l.stripe_unit)
 		nl.stripe_unit = l.stripe_unit;
+	else
+		nl.stripe_unit = ceph_file_layout_su(ci->i_layout);
 	if (l.object_size)
 		nl.object_size = l.object_size;
+	else
+		nl.object_size = ceph_file_layout_object_size(ci->i_layout);
 	if (l.data_pool)
 		nl.data_pool = l.data_pool;
+	else
+		nl.data_pool = ceph_file_layout_pg_pool(ci->i_layout);
+
+	/* this is obsolete, and always -1 */
+	nl.preferred_osd = le64_to_cpu(-1);
 
 	err = __validate_layout(mdsc, &nl);
 	if (err)

fs/ceph/ioctl.h

@@ -34,6 +34,8 @@
 struct ceph_ioctl_layout {
 	__u64 stripe_unit, stripe_count, object_size;
 	__u64 data_pool;
+
+	/* obsolete.  new values ignored, always return -1 */
 	__s64 preferred_osd;
 };