drbd: new-connection and new-minor succeed, if the object already exists

Follow O_CREAT semantics when creating connection or minor device/volume
objects.  If we need O_CREAT|O_EXCL semantics some time down the road,
we can add NLM_F_EXCL to the netlink message flags.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index 9b0312f2d2f87d4e5b54fa6902d3471b8be0d418..0d3753be371c556218d19ccf9d99b5528cbee009 100644 (file)
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -2590,8 +2590,11 @@ int drbd_adm_create_connection(struct sk_buff *skb, struct genl_info *info)
                goto out;
 
        if (adm_ctx.tconn) {
-               retcode = ERR_INVALID_REQUEST;
-               drbd_msg_put_info("connection exists");
+               if (info->nlhdr->nlmsg_flags & NLM_F_EXCL) {
+                       retcode = ERR_INVALID_REQUEST;
+                       drbd_msg_put_info("connection exists");
+               }
+               /* else: still NO_ERROR */
                goto out;
        }
 
@@ -2626,6 +2629,15 @@ int drbd_adm_add_minor(struct sk_buff *skb, struct genl_info *info)
                goto out;
        }
 
+       /* drbd_adm_prepare made sure already
+        * that mdev->tconn and mdev->vnr match the request. */
+       if (adm_ctx.mdev) {
+               if (info->nlhdr->nlmsg_flags & NLM_F_EXCL)
+                       retcode = ERR_MINOR_EXISTS;
+               /* else: still NO_ERROR */
+               goto out;
+       }
+
        retcode = conn_new_minor(adm_ctx.tconn, dh->minor, adm_ctx.volume);
 out:
        drbd_adm_finish(info, retcode);