ocfs2_dlm: Check for migrateable lockres in dlm_empty_lockres()

In dlm_migrate_lockres(), we check upfront whether the lockres is a
candidate for migration. This patch encapsulates that code in a separate
function so that dlm_empty_lockres() can also use it during umount. This
patch addresses the umount process spinning problem.

Signed-off-by: Sunil Mushran <sunil.mushran@oracle.com>
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>

diff --git a/fs/ocfs2/dlm/dlmdomain.c b/fs/ocfs2/dlm/dlmdomain.c
index dbbac18..c558442 100644 (file)
--- a/fs/ocfs2/dlm/dlmdomain.c
+++ b/fs/ocfs2/dlm/dlmdomain.c
@@ -657,6 +657,8 @@ void dlm_unregister_domain(struct dlm_ctxt *dlm)
                dlm_kick_thread(dlm, NULL);
 
                while (dlm_migrate_all_locks(dlm)) {
+                       /* Give dlm_thread time to purge the lockres' */
+                       msleep(500);
                        mlog(0, "%s: more migration to do\n", dlm->name);
                }
                dlm_mark_domain_leaving(dlm);

diff --git a/fs/ocfs2/dlm/dlmmaster.c b/fs/ocfs2/dlm/dlmmaster.c
index 9229e04..6edffca 100644 (file)
--- a/fs/ocfs2/dlm/dlmmaster.c
+++ b/fs/ocfs2/dlm/dlmmaster.c
@@ -2424,6 +2424,57 @@ static void dlm_deref_lockres_worker(struct dlm_work_item *item, void *data)
        dlm_lockres_put(res);
 }
 
+/* Checks whether the lockres can be migrated. Returns 0 if yes, < 0
+ * if not. If 0, numlocks is set to the number of locks in the lockres.
+ */
+static int dlm_is_lockres_migrateable(struct dlm_ctxt *dlm,
+                                     struct dlm_lock_resource *res,
+                                     int *numlocks)
+{
+       int ret;
+       int i;
+       int count = 0;
+       struct list_head *queue, *iter;
+       struct dlm_lock *lock;
+
+       assert_spin_locked(&res->spinlock);
+
+       ret = -EINVAL;
+       if (res->owner == DLM_LOCK_RES_OWNER_UNKNOWN) {
+               mlog(0, "cannot migrate lockres with unknown owner!\n");
+               goto leave;
+       }
+
+       if (res->owner != dlm->node_num) {
+               mlog(0, "cannot migrate lockres this node doesn't own!\n");
+               goto leave;
+       }
+
+       ret = 0;
+       queue = &res->granted;
+       for (i = 0; i < 3; i++) {
+               list_for_each(iter, queue) {
+                       lock = list_entry(iter, struct dlm_lock, list);
+                       ++count;
+                       if (lock->ml.node == dlm->node_num) {
+                               mlog(0, "found a lock owned by this node still "
+                                    "on the %s queue!  will not migrate this "
+                                    "lockres\n", (i == 0 ? "granted" :
+                                                  (i == 1 ? "converting" :
+                                                   "blocked")));
+                               ret = -ENOTEMPTY;
+                               goto leave;
+                       }
+               }
+               queue++;
+       }
+
+       *numlocks = count;
+       mlog(0, "migrateable lockres having %d locks\n", *numlocks);
+
+leave:
+       return ret;
+}
 
 /*
  * DLM_MIGRATE_LOCKRES
@@ -2437,14 +2488,12 @@ static int dlm_migrate_lockres(struct dlm_ctxt *dlm,
        struct dlm_master_list_entry *mle = NULL;
        struct dlm_master_list_entry *oldmle = NULL;
        struct dlm_migratable_lockres *mres = NULL;
-       int ret = -EINVAL;
+       int ret = 0;
        const char *name;
        unsigned int namelen;
        int mle_added = 0;
-       struct list_head *queue, *iter;
-       int i;
-       struct dlm_lock *lock;
-       int empty = 1, wake = 0;
+       int numlocks;
+       int wake = 0;
 
        if (!dlm_grab(dlm))
                return -EINVAL;
@@ -2458,42 +2507,16 @@ static int dlm_migrate_lockres(struct dlm_ctxt *dlm,
         * ensure this lockres is a proper candidate for migration
         */
        spin_lock(&res->spinlock);
-       if (res->owner == DLM_LOCK_RES_OWNER_UNKNOWN) {
-               mlog(0, "cannot migrate lockres with unknown owner!\n");
-               spin_unlock(&res->spinlock);
-               goto leave;
-       }
-       if (res->owner != dlm->node_num) {
-               mlog(0, "cannot migrate lockres this node doesn't own!\n");
+       ret = dlm_is_lockres_migrateable(dlm, res, &numlocks);
+       if (ret < 0) {
                spin_unlock(&res->spinlock);
                goto leave;
        }
-       mlog(0, "checking queues...\n");
-       queue = &res->granted;
-       for (i=0; i<3; i++) {
-               list_for_each(iter, queue) {
-                       lock = list_entry (iter, struct dlm_lock, list);
-                       empty = 0;
-                       if (lock->ml.node == dlm->node_num) {
-                               mlog(0, "found a lock owned by this node "
-                                    "still on the %s queue!  will not "
-                                    "migrate this lockres\n",
-                                    i==0 ? "granted" :
-                                    (i==1 ? "converting" : "blocked"));
-                               spin_unlock(&res->spinlock);
-                               ret = -ENOTEMPTY;
-                               goto leave;
-                       }
-               }
-               queue++;
-       }
-       mlog(0, "all locks on this lockres are nonlocal.  continuing\n");
        spin_unlock(&res->spinlock);
 
        /* no work to do */
-       if (empty) {
+       if (numlocks == 0) {
                mlog(0, "no locks were found on this lockres! done!\n");
-               ret = 0;
                goto leave;
        }
 
@@ -2729,6 +2752,7 @@ int dlm_empty_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *res)
 {
        int ret;
        int lock_dropped = 0;
+       int numlocks;
 
        spin_lock(&res->spinlock);
        if (res->owner != dlm->node_num) {
@@ -2740,6 +2764,13 @@ int dlm_empty_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *res)
                spin_unlock(&res->spinlock);
                goto leave;
        }
+
+       /* No need to migrate a lockres having no locks */
+       ret = dlm_is_lockres_migrateable(dlm, res, &numlocks);
+       if (ret >= 0 && numlocks == 0) {
+               spin_unlock(&res->spinlock);
+               goto leave;
+       }
        spin_unlock(&res->spinlock);
 
        /* Wheee! Migrate lockres here! Will sleep so drop spinlock. */