[DLM] add lock timeouts and warnings [2/6]

New features: lock timeouts and time warnings.  If the DLM_LKF_TIMEOUT
flag is set, then the request/conversion will be canceled after waiting
the specified number of centiseconds (specified per lock).  This feature
is only available for locks requested through libdlm (can be enabled for
kernel dlm users if there's a use for it.)

If the new DLM_LSFL_TIMEWARN flag is set when creating the lockspace, then
a warning message will be sent to userspace (using genetlink) after a
request/conversion has been waiting for a given number of centiseconds
(configurable per node).  The time warnings will be used in the future
to do deadlock detection in userspace.

Signed-off-by: David Teigland <teigland@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 155 insertions, 0 deletions

diff --git a/fs/dlm/netlink.c b/fs/dlm/netlink.c
new file mode 100644
index 000000000000..804b32cd22c1
--- /dev/null
+++ b/fs/dlm/netlink.c
@@ -0,0 +1,155 @@
+/*
+ * Copyright (C) 2007 Red Hat, Inc.  All rights reserved.
+ *
+ * This copyrighted material is made available to anyone wishing to use,
+ * modify, copy, or redistribute it subject to the terms and conditions
+ * of the GNU General Public License v.2.
+ */
+
+#include <net/genetlink.h>
+#include <linux/dlm.h>
+#include <linux/dlm_netlink.h>
+
+#include "dlm_internal.h"
+
+static uint32_t dlm_nl_seqnum;
+static uint32_t listener_nlpid;
+
+static struct genl_family family = {
+        .id             = GENL_ID_GENERATE,
+        .name           = DLM_GENL_NAME,
+        .version        = DLM_GENL_VERSION,
+};
+
+static int prepare_data(u8 cmd, struct sk_buff **skbp, size_t size)
+{
+        struct sk_buff *skb;
+        void *data;
+
+        skb = genlmsg_new(size, GFP_KERNEL);
+        if (!skb)
+                return -ENOMEM;
+
+        /* add the message headers */
+        data = genlmsg_put(skb, 0, dlm_nl_seqnum++, &family, 0, cmd);
+        if (!data) {
+                nlmsg_free(skb);
+                return -EINVAL;
+        }
+
+        *skbp = skb;
+        return 0;
+}
+
+static struct dlm_lock_data *mk_data(struct sk_buff *skb)
+{
+        struct nlattr *ret;
+
+        ret = nla_reserve(skb, DLM_TYPE_LOCK, sizeof(struct dlm_lock_data));
+        if (!ret)
+                return NULL;
+        return nla_data(ret);
+}
+
+static int send_data(struct sk_buff *skb)
+{
+        struct genlmsghdr *genlhdr = nlmsg_data((struct nlmsghdr *)skb->data);
+        void *data = genlmsg_data(genlhdr);
+        int rv;
+
+        rv = genlmsg_end(skb, data);
+        if (rv < 0) {
+                nlmsg_free(skb);
+                return rv;
+        }
+
+        return genlmsg_unicast(skb, listener_nlpid);
+}
+
+static int user_cmd(struct sk_buff *skb, struct genl_info *info)
+{
+        listener_nlpid = info->snd_pid;
+        printk("user_cmd nlpid %u\n", listener_nlpid);
+        return 0;
+}
+
+static struct genl_ops dlm_nl_ops = {
+        .cmd            = DLM_CMD_HELLO,
+        .doit           = user_cmd,
+};
+
+int dlm_netlink_init(void)
+{
+        int rv;
+
+        rv = genl_register_family(&family);
+        if (rv)
+                return rv;
+
+        rv = genl_register_ops(&family, &dlm_nl_ops);
+        if (rv < 0)
+                goto err;
+        return 0;
+ err:
+        genl_unregister_family(&family);
+        return rv;
+}
+
+void dlm_netlink_exit(void)
+{
+        genl_unregister_ops(&family, &dlm_nl_ops);
+        genl_unregister_family(&family);
+}
+
+static void fill_data(struct dlm_lock_data *data, struct dlm_lkb *lkb)
+{
+        struct dlm_rsb *r = lkb->lkb_resource;
+        struct dlm_user_args *ua = (struct dlm_user_args *) lkb->lkb_astparam;
+
+        memset(data, 0, sizeof(struct dlm_lock_data));
+
+        data->version = DLM_LOCK_DATA_VERSION;
+        data->nodeid = lkb->lkb_nodeid;
+        data->ownpid = lkb->lkb_ownpid;
+        data->id = lkb->lkb_id;
+        data->remid = lkb->lkb_remid;
+        data->status = lkb->lkb_status;
+        data->grmode = lkb->lkb_grmode;
+        data->rqmode = lkb->lkb_rqmode;
+        data->timestamp = lkb->lkb_timestamp;
+        if (ua)
+                data->xid = ua->xid;
+        if (r) {
+                data->lockspace_id = r->res_ls->ls_global_id;
+                data->resource_namelen = r->res_length;
+                memcpy(data->resource_name, r->res_name, r->res_length);
+        }
+}
+
+void dlm_timeout_warn(struct dlm_lkb *lkb)
+{
+        struct dlm_lock_data *data;
+        struct sk_buff *send_skb;
+        size_t size;
+        int rv;
+
+        log_debug(lkb->lkb_resource->res_ls, "timeout_warn %x", lkb->lkb_id);
+
+        size = nla_total_size(sizeof(struct dlm_lock_data)) +
+               nla_total_size(0); /* why this? */
+
+        rv = prepare_data(DLM_CMD_TIMEOUT, &send_skb, size);
+        if (rv < 0)
+                return;
+
+        data = mk_data(send_skb);
+        if (!data) {
+                nlmsg_free(send_skb);
+                return;
+        }
+
+        fill_data(data, lkb);
+
+        send_data(send_skb);
+}
+