ocfs2_dlm: fix cluster-wide refcounting of lock resources

This was previously broken and migration of some locks had to be temporarily
disabled. We use a new (and backward-incompatible) set of network messages
to account for all references to a lock resources held across the cluster.
once these are all freed, the master node may then free the lock resource
memory once its local references are dropped.

Signed-off-by: Kurt Hackel <kurt.hackel@oracle.com>
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>

1 files changed, 116 insertions, 7 deletions

diff --git a/fs/ocfs2/dlm/dlmrecovery.c b/fs/ocfs2/dlm/dlmrecovery.c
index 367a11e9e2ed..d011a2a22742 100644
--- a/fs/ocfs2/dlm/dlmrecovery.c
+++ b/fs/ocfs2/dlm/dlmrecovery.c
@@ -1129,6 +1129,11 @@ static int dlm_send_mig_lockres_msg(struct dlm_ctxt *dlm,
         if (total_locks == mres_total_locks)
                 mres->flags |= DLM_MRES_ALL_DONE;
 
+        mlog(0, "%s:%.*s: sending mig lockres (%s) to %u\n",
+             dlm->name, res->lockname.len, res->lockname.name,
+             orig_flags & DLM_MRES_MIGRATION ? "migrate" : "recovery",
+             send_to);
+
         /* send it */
         ret = o2net_send_message(DLM_MIG_LOCKRES_MSG, dlm->key, mres,
                                  sz, send_to, &status);
@@ -1213,6 +1218,34 @@ static int dlm_add_lock_to_array(struct dlm_lock *lock,
         return 0;
 }
 
+static void dlm_add_dummy_lock(struct dlm_ctxt *dlm,
+                               struct dlm_migratable_lockres *mres)
+{
+        struct dlm_lock dummy;
+        memset(&dummy, 0, sizeof(dummy));
+        dummy.ml.cookie = 0;
+        dummy.ml.type = LKM_IVMODE;
+        dummy.ml.convert_type = LKM_IVMODE;
+        dummy.ml.highest_blocked = LKM_IVMODE;
+        dummy.lksb = NULL;
+        dummy.ml.node = dlm->node_num;
+        dlm_add_lock_to_array(&dummy, mres, DLM_BLOCKED_LIST);
+}
+
+static inline int dlm_is_dummy_lock(struct dlm_ctxt *dlm,
+                                    struct dlm_migratable_lock *ml,
+                                    u8 *nodenum)
+{
+        if (unlikely(ml->cookie == 0 &&
+            ml->type == LKM_IVMODE &&
+            ml->convert_type == LKM_IVMODE &&
+            ml->highest_blocked == LKM_IVMODE &&
+            ml->list == DLM_BLOCKED_LIST)) {
+                *nodenum = ml->node;
+                return 1;
+        }
+        return 0;
+}
 
 int dlm_send_one_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *res,
                          struct dlm_migratable_lockres *mres,
@@ -1260,6 +1293,14 @@ int dlm_send_one_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *res,
                                 goto error;
                 }
         }
+        if (total_locks == 0) {
+                /* send a dummy lock to indicate a mastery reference only */
+                mlog(0, "%s:%.*s: sending dummy lock to %u, %s\n",
+                     dlm->name, res->lockname.len, res->lockname.name,
+                     send_to, flags & DLM_MRES_RECOVERY ? "recovery" :
+                     "migration");
+                dlm_add_dummy_lock(dlm, mres);
+        }
         /* flush any remaining locks */
         ret = dlm_send_mig_lockres_msg(dlm, mres, send_to, res, total_locks);
         if (ret < 0)
@@ -1386,13 +1427,16 @@ int dlm_mig_lockres_handler(struct o2net_msg *msg, u32 len, void *data)
                 /* add an extra ref for just-allocated lockres 
                  * otherwise the lockres will be purged immediately */
                 dlm_lockres_get(res);
-
         }
 
         /* at this point we have allocated everything we need,
          * and we have a hashed lockres with an extra ref and
          * the proper res->state flags. */
         ret = 0;
+        spin_lock(&res->spinlock);
+        /* drop this either when master requery finds a different master
+         * or when a lock is added by the recovery worker */
+        dlm_lockres_grab_inflight_ref(dlm, res);
         if (mres->master == DLM_LOCK_RES_OWNER_UNKNOWN) {
                 /* migration cannot have an unknown master */
                 BUG_ON(!(mres->flags & DLM_MRES_RECOVERY));
@@ -1400,10 +1444,11 @@ int dlm_mig_lockres_handler(struct o2net_msg *msg, u32 len, void *data)
                           "unknown owner.. will need to requery: "
                           "%.*s\n", mres->lockname_len, mres->lockname);
         } else {
-                spin_lock(&res->spinlock);
+                /* take a reference now to pin the lockres, drop it
+                 * when locks are added in the worker */
                 dlm_change_lockres_owner(dlm, res, dlm->node_num);
-                spin_unlock(&res->spinlock);
         }
+        spin_unlock(&res->spinlock);
 
         /* queue up work for dlm_mig_lockres_worker */
         dlm_grab(dlm);  /* get an extra ref for the work item */
@@ -1459,6 +1504,9 @@ again:
                                    "this node will take it.\n",
                                    res->lockname.len, res->lockname.name);
                 } else {
+                        spin_lock(&res->spinlock);
+                        dlm_lockres_drop_inflight_ref(dlm, res);
+                        spin_unlock(&res->spinlock);
                         mlog(0, "master needs to respond to sender "
                                   "that node %u still owns %.*s\n",
                                   real_master, res->lockname.len,
@@ -1666,10 +1714,25 @@ static int dlm_process_recovery_data(struct dlm_ctxt *dlm,
         int i, bad;
         struct list_head *iter;
         struct dlm_lock *lock = NULL;
+        u8 from = O2NM_MAX_NODES;
+        unsigned int added = 0;
 
         mlog(0, "running %d locks for this lockres\n", mres->num_locks);
         for (i=0; i<mres->num_locks; i++) {
                 ml = &(mres->ml[i]);
+
+                if (dlm_is_dummy_lock(dlm, ml, &from)) {
+                        /* placeholder, just need to set the refmap bit */
+                        BUG_ON(mres->num_locks != 1);
+                        mlog(0, "%s:%.*s: dummy lock for %u\n",
+                             dlm->name, mres->lockname_len, mres->lockname,
+                             from);
+                        spin_lock(&res->spinlock);
+                        dlm_lockres_set_refmap_bit(from, res);
+                        spin_unlock(&res->spinlock);
+                        added++;
+                        break;
+                }
                 BUG_ON(ml->highest_blocked != LKM_IVMODE);
                 newlock = NULL;
                 lksb = NULL;
@@ -1711,6 +1774,7 @@ static int dlm_process_recovery_data(struct dlm_ctxt *dlm,
                         /* do not alter lock refcount.  switching lists. */
                         list_move_tail(&lock->list, queue);
                         spin_unlock(&res->spinlock);
+                        added++;
 
                         mlog(0, "just reordered a local lock!\n");
                         continue;
@@ -1817,12 +1881,24 @@ skip_lvb:
                 if (!bad) {
                         dlm_lock_get(newlock);
                         list_add_tail(&newlock->list, queue);
+                        mlog(0, "%s:%.*s: added lock for node %u, "
+                             "setting refmap bit\n", dlm->name,
+                             res->lockname.len, res->lockname.name, ml->node);
+                        dlm_lockres_set_refmap_bit(ml->node, res);
+                        added++;
                 }
                 spin_unlock(&res->spinlock);
         }
         mlog(0, "done running all the locks\n");
 
 leave:
+        /* balance the ref taken when the work was queued */
+        if (added > 0) {
+                spin_lock(&res->spinlock);
+                dlm_lockres_drop_inflight_ref(dlm, res);
+                spin_unlock(&res->spinlock);
+        }
+
         if (ret < 0) {
                 mlog_errno(ret);
                 if (newlock)
@@ -1935,9 +2011,11 @@ static void dlm_finish_local_lockres_recovery(struct dlm_ctxt *dlm,
                 if (res->owner == dead_node) {
                         list_del_init(&res->recovering);
                         spin_lock(&res->spinlock);
+                        /* new_master has our reference from
+                         * the lock state sent during recovery */
                         dlm_change_lockres_owner(dlm, res, new_master);
                         res->state &= ~DLM_LOCK_RES_RECOVERING;
-                        if (!__dlm_lockres_unused(res))
+                        if (__dlm_lockres_has_locks(res))
                                 __dlm_dirty_lockres(dlm, res);
                         spin_unlock(&res->spinlock);
                         wake_up(&res->wq);
@@ -1977,9 +2055,11 @@ static void dlm_finish_local_lockres_recovery(struct dlm_ctxt *dlm,
                                         dlm_lockres_put(res);
                                 }
                                 spin_lock(&res->spinlock);
+                                /* new_master has our reference from
+                                 * the lock state sent during recovery */
                                 dlm_change_lockres_owner(dlm, res, new_master);
                                 res->state &= ~DLM_LOCK_RES_RECOVERING;
-                                if (!__dlm_lockres_unused(res))
+                                if (__dlm_lockres_has_locks(res))
                                         __dlm_dirty_lockres(dlm, res);
                                 spin_unlock(&res->spinlock);
                                 wake_up(&res->wq);
@@ -2048,6 +2128,7 @@ static void dlm_free_dead_locks(struct dlm_ctxt *dlm,
 {
         struct list_head *iter, *tmpiter;
         struct dlm_lock *lock;
+        unsigned int freed = 0;
 
         /* this node is the lockres master:
          * 1) remove any stale locks for the dead node
@@ -2062,6 +2143,7 @@ static void dlm_free_dead_locks(struct dlm_ctxt *dlm,
                 if (lock->ml.node == dead_node) {
                         list_del_init(&lock->list);
                         dlm_lock_put(lock);
+                        freed++;
                 }
         }
         list_for_each_safe(iter, tmpiter, &res->converting) {
@@ -2069,6 +2151,7 @@ static void dlm_free_dead_locks(struct dlm_ctxt *dlm,
                 if (lock->ml.node == dead_node) {
                         list_del_init(&lock->list);
                         dlm_lock_put(lock);
+                        freed++;
                 }
         }
         list_for_each_safe(iter, tmpiter, &res->blocked) {
@@ -2076,9 +2159,23 @@ static void dlm_free_dead_locks(struct dlm_ctxt *dlm,
                 if (lock->ml.node == dead_node) {
                         list_del_init(&lock->list);
                         dlm_lock_put(lock);
+                        freed++;
                 }
         }
 
+        if (freed) {
+                mlog(0, "%s:%.*s: freed %u locks for dead node %u, "
+                     "dropping ref from lockres\n", dlm->name,
+                     res->lockname.len, res->lockname.name, freed, dead_node);
+                BUG_ON(!test_bit(dead_node, res->refmap));
+                dlm_lockres_clear_refmap_bit(dead_node, res);
+        } else if (test_bit(dead_node, res->refmap)) {
+                mlog(0, "%s:%.*s: dead node %u had a ref, but had "
+                     "no locks and had not purged before dying\n", dlm->name,
+                     res->lockname.len, res->lockname.name, dead_node);
+                dlm_lockres_clear_refmap_bit(dead_node, res);
+        }
+
         /* do not kick thread yet */
         __dlm_dirty_lockres(dlm, res);
 }
@@ -2141,9 +2238,21 @@ static void dlm_do_local_recovery_cleanup(struct dlm_ctxt *dlm, u8 dead_node)
                         spin_lock(&res->spinlock);
                         /* zero the lvb if necessary */
                         dlm_revalidate_lvb(dlm, res, dead_node);
-                        if (res->owner == dead_node)
+                        if (res->owner == dead_node) {
+                                if (res->state & DLM_LOCK_RES_DROPPING_REF)
+                                        mlog(0, "%s:%.*s: owned by "
+                                             "dead node %u, this node was "
+                                             "dropping its ref when it died. "
+                                             "continue, dropping the flag.\n",
+                                             dlm->name, res->lockname.len,
+                                             res->lockname.name, dead_node);
+
+                                /* the wake_up for this will happen when the
+                                 * RECOVERING flag is dropped later */
+                                res->state &= ~DLM_LOCK_RES_DROPPING_REF;
+
                                 dlm_move_lockres_to_recovery_list(dlm, res);
-                        else if (res->owner == dlm->node_num) {
+                        } else if (res->owner == dlm->node_num) {
                                 dlm_free_dead_locks(dlm, res, dead_node);
                                 __dlm_lockres_calc_usage(dlm, res);
                         }