LU-6273 lwp: notify LWP users in dedicated thread

[fs/lustre-release.git] / lustre / osp / lwp_dev.c

diff --git a/lustre/osp/lwp_dev.c b/lustre/osp/lwp_dev.c
index 73d5deb..574323e 100644 (file)
--- a/lustre/osp/lwp_dev.c
+++ b/lustre/osp/lwp_dev.c
@@ -42,6 +42,7 @@
 #include <obd_class.h>
 #include <lustre_param.h>
 #include <lustre_log.h>
+#include <linux/kthread.h>
 
 #include "osp_internal.h"
 
@@ -50,6 +51,7 @@ struct lwp_device {
        struct obd_device      *lpd_obd;   /* corresponding OBD device */
        struct obd_uuid         lpd_cluuid;/* UUID of LWP */
        struct obd_export      *lpd_exp;   /* export of LWP */
+       struct ptlrpc_thread    lpd_notify_thread; /* notify thread */
        int                     lpd_connects; /* use count, 0 or 1 */
 };
 
@@ -87,6 +89,9 @@ static int lwp_setup(const struct lu_env *env, struct lwp_device *lwp,
        int                      rc;
        ENTRY;
 
+       thread_set_flags(&lwp->lpd_notify_thread, SVC_STOPPED);
+       init_waitqueue_head(&lwp->lpd_notify_thread.t_ctl_waitq);
+
        OBD_ALLOC_PTR(bufs);
        if (bufs == NULL)
                RETURN(-ENOMEM);
@@ -353,11 +358,17 @@ static struct lu_device *lwp_device_alloc(const struct lu_env *env,
 static struct lu_device *lwp_device_fini(const struct lu_env *env,
                                         struct lu_device *ludev)
 {
-       struct lwp_device *m = lu2lwp_dev(ludev);
-       struct obd_import *imp;
-       int                rc;
+       struct lwp_device       *m = lu2lwp_dev(ludev);
+       struct ptlrpc_thread    *thread = &m->lpd_notify_thread;
+       struct l_wait_info       lwi = { 0 };
+       struct obd_import       *imp;
+       int                      rc;
        ENTRY;
 
+       if (!thread_is_stopped(thread))
+               l_wait_event(thread->t_ctl_waitq, thread_is_stopped(thread),
+                            &lwi);
+
        if (m->lpd_exp != NULL)
                class_disconnect(m->lpd_exp);
 
@@ -388,6 +399,65 @@ struct lu_device_type lwp_device_type = {
        .ldt_ctx_tags = LCT_MD_THREAD
 };
 
+static int lwp_notify_main(void *args)
+{
+       struct obd_export       *exp = (struct obd_export *)args;
+       struct lwp_device       *lwp;
+       struct ptlrpc_thread    *thread;
+
+       LASSERT(exp != NULL);
+       lwp = lu2lwp_dev(exp->exp_obd->obd_lu_dev);
+       thread = &lwp->lpd_notify_thread;
+
+       thread_set_flags(thread, SVC_RUNNING);
+       wake_up(&thread->t_ctl_waitq);
+
+       lustre_notify_lwp_list(exp);
+
+       thread_set_flags(thread, SVC_STOPPED);
+       wake_up(&thread->t_ctl_waitq);
+       return 0;
+}
+
+/*
+ * Some notify callbacks may cause deadlock in failover
+ * scenario, so we have to start thread to run callbacks
+ * asynchronously. See LU-6273.
+ */
+static void lwp_notify_users(struct obd_export *exp)
+{
+       struct lwp_device       *lwp;
+       struct ptlrpc_thread    *thread;
+       struct task_struct      *task;
+       struct l_wait_info       lwi = { 0 };
+       char                     name[MTI_NAME_MAXLEN];
+
+       LASSERT(exp != NULL);
+       lwp = lu2lwp_dev(exp->exp_obd->obd_lu_dev);
+       thread = &lwp->lpd_notify_thread;
+
+       snprintf(name, MTI_NAME_MAXLEN, "lwp_notify_%s",
+                exp->exp_obd->obd_name);
+
+       /* Notify happens only on LWP setup, so there shouldn't
+        * be notify thread running */
+       if (!thread_is_stopped(thread)) {
+               CERROR("LWP notify thread: %s wasn't stopped\n", name);
+               return;
+       }
+
+       task = kthread_run(lwp_notify_main, exp, name);
+       if (IS_ERR(task)) {
+               thread_set_flags(thread, SVC_STOPPED);
+               CERROR("Failed to start LWP notify thread:%s. %lu\n",
+                      name, PTR_ERR(task));
+       }
+
+       l_wait_event(thread->t_ctl_waitq,
+                    thread_is_running(thread) || thread_is_stopped(thread),
+                    &lwi);
+}
+
 /**
  * Implementation of OBD device operations obd_ops::o_connect.
  *
@@ -464,6 +534,9 @@ out_dis:
 out_sem:
        up_write(&cli->cl_sem);
 
+       if (rc == 0)
+               lwp_notify_users(*exp);
+
        return rc;
 }