[PATCH] ocfs2: fix hang in dlm lock resource mastery

fixes hangs in lock mastery related to refcounting on the mle structure

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

1 files changed, 92 insertions, 32 deletions

diff --git a/fs/ocfs2/dlm/dlmmaster.c b/fs/ocfs2/dlm/dlmmaster.c
index 847dd3cc4cf5..78ac3a00eb54 100644
--- a/fs/ocfs2/dlm/dlmmaster.c
+++ b/fs/ocfs2/dlm/dlmmaster.c
@@ -792,7 +792,15 @@ redo_request:
                         mlog_errno(ret);
                 if (mle->master != O2NM_MAX_NODES) {
                         /* found a master ! */
-                        break;
+                        if (mle->master <= nodenum)
+                                break;
+                        /* if our master request has not reached the master
+                         * yet, keep going until it does.  this is how the
+                         * master will know that asserts are needed back to
+                         * the lower nodes. */
+                        mlog(0, "%s:%.*s: requests only up to %u but master "
+                             "is %u, keep going\n", dlm->name, namelen,
+                             lockid, nodenum, mle->master);
                 }
         }
 
@@ -860,7 +868,19 @@ recheck:
         /* check if another node has already become the owner */
         spin_lock(&res->spinlock);
         if (res->owner != DLM_LOCK_RES_OWNER_UNKNOWN) {
+                mlog(0, "%s:%.*s: owner is suddenly %u\n", dlm->name,
+                     res->lockname.len, res->lockname.name, res->owner);
                 spin_unlock(&res->spinlock);
+                /* this will cause the master to re-assert across
+                 * the whole cluster, freeing up mles */
+                ret = dlm_do_master_request(mle, res->owner);
+                if (ret < 0) {
+                        /* give recovery a chance to run */
+                        mlog(ML_ERROR, "link to %u went down?: %d\n", res->owner, ret);
+                        msleep(500);
+                        goto recheck;
+                }
+                ret = 0;
                 goto leave;
         }
         spin_unlock(&res->spinlock);
@@ -1244,13 +1264,14 @@ int dlm_master_request_handler(struct o2net_msg *msg, u32 len, void *data)
 {
         u8 response = DLM_MASTER_RESP_MAYBE;
         struct dlm_ctxt *dlm = data;
-        struct dlm_lock_resource *res;
+        struct dlm_lock_resource *res = NULL;
         struct dlm_master_request *request = (struct dlm_master_request *) msg->buf;
         struct dlm_master_list_entry *mle = NULL, *tmpmle = NULL;
         char *name;
         unsigned int namelen;
         int found, ret;
         int set_maybe;
+        int dispatch_assert = 0;
 
         if (!dlm_grab(dlm))
                 return DLM_MASTER_RESP_NO;
@@ -1287,7 +1308,6 @@ way_up_top:
                 }
 
                 if (res->owner == dlm->node_num) {
-                        u32 flags = DLM_ASSERT_MASTER_MLE_CLEANUP;
                         spin_unlock(&res->spinlock);
                         // mlog(0, "this node is the master\n");
                         response = DLM_MASTER_RESP_YES;
@@ -1300,16 +1320,7 @@ way_up_top:
                          * caused all nodes up to this one to
                          * create mles.  this node now needs to
                          * go back and clean those up. */
-                        mlog(0, "%u is the owner of %.*s, cleaning everyone else\n",
-                             dlm->node_num, res->lockname.len, res->lockname.name);
-                        ret = dlm_dispatch_assert_master(dlm, res, 1,
-                                                         request->node_idx,
-                                                         flags);
-                        if (ret < 0) {
-                                mlog(ML_ERROR, "failed to dispatch assert "
-                                     "master work\n");
-                                response = DLM_MASTER_RESP_ERROR;
-                        }
+                        dispatch_assert = 1;
                         goto send_response;
                 } else if (res->owner != DLM_LOCK_RES_OWNER_UNKNOWN) {
                         spin_unlock(&res->spinlock);
@@ -1357,9 +1368,13 @@ way_up_top:
                         }
                 } else if (tmpmle->master != DLM_LOCK_RES_OWNER_UNKNOWN) {
                         set_maybe = 0;
-                        if (tmpmle->master == dlm->node_num)
+                        if (tmpmle->master == dlm->node_num) {
                                 response = DLM_MASTER_RESP_YES;
-                        else
+                                /* this node will be the owner.
+                                 * go back and clean the mles on any
+                                 * other nodes */
+                                dispatch_assert = 1;
+                        } else
                                 response = DLM_MASTER_RESP_NO;
                 } else {
                         // mlog(0, "this node is attempting to "
@@ -1398,8 +1413,8 @@ way_up_top:
                         mle = (struct dlm_master_list_entry *)
                                 kmem_cache_alloc(dlm_mle_cache, GFP_KERNEL);
                         if (!mle) {
-                                // bad bad bad... this sucks.
                                 response = DLM_MASTER_RESP_ERROR;
+                                mlog_errno(-ENOMEM);
                                 goto send_response;
                         }
                         spin_lock(&dlm->spinlock);
@@ -1418,25 +1433,19 @@ way_up_top:
                 // mlog(0, "mle was found\n");
                 set_maybe = 1;
                 spin_lock(&tmpmle->spinlock);
+                if (tmpmle->master == dlm->node_num) {
+                        mlog(ML_ERROR, "no lockres, but an mle with this node as master!\n");
+                        BUG();
+                }
                 if (tmpmle->type == DLM_MLE_BLOCK)
                         response = DLM_MASTER_RESP_NO;
                 else if (tmpmle->type == DLM_MLE_MIGRATION) {
                         mlog(0, "migration mle was found (%u->%u)\n",
                              tmpmle->master, tmpmle->new_master);
-                        if (tmpmle->master == dlm->node_num) {
-                                mlog(ML_ERROR, "no lockres, but migration mle "
-                                     "says that this node is master!\n");
-                                BUG();
-                        }
                         /* real master can respond on its own */
                         response = DLM_MASTER_RESP_NO;
-                } else {
-                        if (tmpmle->master == dlm->node_num) {
-                                response = DLM_MASTER_RESP_YES;
-                                set_maybe = 0;
-                        } else
-                                response = DLM_MASTER_RESP_MAYBE;
-                }
+                } else
+                        response = DLM_MASTER_RESP_MAYBE;
                 if (set_maybe)
                         set_bit(request->node_idx, tmpmle->maybe_map);
                 spin_unlock(&tmpmle->spinlock);
@@ -1449,6 +1458,24 @@ way_up_top:
                 dlm_put_mle(tmpmle);
         }
 send_response:
+
+        if (dispatch_assert) {
+                if (response != DLM_MASTER_RESP_YES)
+                        mlog(ML_ERROR, "invalid response %d\n", response);
+                if (!res) {
+                        mlog(ML_ERROR, "bad lockres while trying to assert!\n");
+                        BUG();
+                }
+                mlog(0, "%u is the owner of %.*s, cleaning everyone else\n",
+                             dlm->node_num, res->lockname.len, res->lockname.name);
+                ret = dlm_dispatch_assert_master(dlm, res, 0, request->node_idx, 
+                                                 DLM_ASSERT_MASTER_MLE_CLEANUP);
+                if (ret < 0) {
+                        mlog(ML_ERROR, "failed to dispatch assert master work\n");
+                        response = DLM_MASTER_RESP_ERROR;
+                }
+        }
+
         dlm_put(dlm);
         return response;
 }
@@ -1471,8 +1498,11 @@ static int dlm_do_assert_master(struct dlm_ctxt *dlm, const char *lockname,
         int to, tmpret;
         struct dlm_node_iter iter;
         int ret = 0;
+        int reassert;
 
         BUG_ON(namelen > O2NM_MAX_NAME_LEN);
+again:
+        reassert = 0;
 
         /* note that if this nodemap is empty, it returns 0 */
         dlm_node_iter_init(nodemap, &iter);
@@ -1504,9 +1534,17 @@ static int dlm_do_assert_master(struct dlm_ctxt *dlm, const char *lockname,
                              "got %d.\n", namelen, lockname, to, r);
                         dlm_dump_lock_resources(dlm);
                         BUG();
+                } else if (r == EAGAIN) {
+                        mlog(0, "%.*s: node %u create mles on other "
+                             "nodes and requests a re-assert\n", 
+                             namelen, lockname, to);
+                        reassert = 1;
                 }
         }
 
+        if (reassert)
+                goto again;
+
         return ret;
 }
 
@@ -1528,6 +1566,8 @@ int dlm_assert_master_handler(struct o2net_msg *msg, u32 len, void *data)
         char *name;
         unsigned int namelen;
         u32 flags;
+        int master_request = 0;
+        int ret = 0;
 
         if (!dlm_grab(dlm))
                 return 0;
@@ -1642,11 +1682,22 @@ ok:
         // mlog(0, "woo!  got an assert_master from node %u!\n",
         //           assert->node_idx);
         if (mle) {
-                int extra_ref;
+                int extra_ref = 0;
+                int nn = -1;
                 
                 spin_lock(&mle->spinlock);
-                extra_ref = !!(mle->type == DLM_MLE_BLOCK
-                               || mle->type == DLM_MLE_MIGRATION);
+                if (mle->type == DLM_MLE_BLOCK || mle->type == DLM_MLE_MIGRATION)
+                        extra_ref = 1;
+                else {
+                        /* MASTER mle: if any bits set in the response map
+                         * then the calling node needs to re-assert to clear
+                         * up nodes that this node contacted */
+                        while ((nn = find_next_bit (mle->response_map, O2NM_MAX_NODES, 
+                                                    nn+1)) < O2NM_MAX_NODES) {
+                                if (nn != dlm->node_num && nn != assert->node_idx)
+                                        master_request = 1;
+                        }
+                }
                 mle->master = assert->node_idx;
                 atomic_set(&mle->woken, 1);
                 wake_up(&mle->wq);
@@ -1677,10 +1728,15 @@ ok:
         }
 
 done:
+        ret = 0;
         if (res)
                 dlm_lockres_put(res);
         dlm_put(dlm);
-        return 0;
+        if (master_request) {
+                mlog(0, "need to tell master to reassert\n");
+                ret = EAGAIN;  // positive. negative would shoot down the node.
+        }
+        return ret;
 
 kill:
         /* kill the caller! */
@@ -1713,6 +1769,10 @@ int dlm_dispatch_assert_master(struct dlm_ctxt *dlm,
         item->u.am.request_from = request_from;
         item->u.am.flags = flags;
 
+        if (ignore_higher) 
+                mlog(0, "IGNORE HIGHER: %.*s\n", res->lockname.len, 
+                     res->lockname.name);
+                
         spin_lock(&dlm->work_lock);
         list_add_tail(&item->list, &dlm->work_list);
         spin_unlock(&dlm->work_lock);