dlm: recover locks waiting for overlap replies

When recovery looks at locks waiting for replies, it fails to consider
locks that have already received a reply for their first remote operation,
but not received a reply for secondary, overlapping unlock/cancel.  The
appropriate stub reply needs to be called for these waiters.

Appears when we start doing recovery in the presence of a many overlapping
unlock/cancel ops.

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

diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c
index 43ca2a30c4134f725b8591f9ff95dc4f2e0fb5ee..a758f1b80e3b3cf05dbd0c5df8b2887df45f1c96 100644 (file)
--- a/fs/dlm/lock.c
+++ b/fs/dlm/lock.c
@@ -3846,6 +3846,7 @@ static int waiter_needs_recovery(struct dlm_ls *ls, struct dlm_lkb *lkb)
 void dlm_recover_waiters_pre(struct dlm_ls *ls)
 {
        struct dlm_lkb *lkb, *safe;
+       int wait_type, stub_unlock_result, stub_cancel_result;
 
        mutex_lock(&ls->ls_waiters_mutex);
 
@@ -3864,7 +3865,33 @@ void dlm_recover_waiters_pre(struct dlm_ls *ls)
                if (!waiter_needs_recovery(ls, lkb))
                        continue;
 
-               switch (lkb->lkb_wait_type) {
+               wait_type = lkb->lkb_wait_type;
+               stub_unlock_result = -DLM_EUNLOCK;
+               stub_cancel_result = -DLM_ECANCEL;
+
+               /* Main reply may have been received leaving a zero wait_type,
+                  but a reply for the overlapping op may not have been
+                  received.  In that case we need to fake the appropriate
+                  reply for the overlap op. */
+
+               if (!wait_type) {
+                       if (is_overlap_cancel(lkb)) {
+                               wait_type = DLM_MSG_CANCEL;
+                               if (lkb->lkb_grmode == DLM_LOCK_IV)
+                                       stub_cancel_result = 0;
+                       }
+                       if (is_overlap_unlock(lkb)) {
+                               wait_type = DLM_MSG_UNLOCK;
+                               if (lkb->lkb_grmode == DLM_LOCK_IV)
+                                       stub_unlock_result = -ENOENT;
+                       }
+
+                       log_debug(ls, "rwpre overlap %x %x %d %d %d",
+                                 lkb->lkb_id, lkb->lkb_flags, wait_type,
+                                 stub_cancel_result, stub_unlock_result);
+               }
+
+               switch (wait_type) {
 
                case DLM_MSG_REQUEST:
                        lkb->lkb_flags |= DLM_IFL_RESEND;
@@ -3877,7 +3904,7 @@ void dlm_recover_waiters_pre(struct dlm_ls *ls)
                case DLM_MSG_UNLOCK:
                        hold_lkb(lkb);
                        ls->ls_stub_ms.m_type = DLM_MSG_UNLOCK_REPLY;
-                       ls->ls_stub_ms.m_result = -DLM_EUNLOCK;
+                       ls->ls_stub_ms.m_result = stub_unlock_result;
                        ls->ls_stub_ms.m_flags = lkb->lkb_flags;
                        _receive_unlock_reply(lkb, &ls->ls_stub_ms);
                        dlm_put_lkb(lkb);
@@ -3886,15 +3913,15 @@ void dlm_recover_waiters_pre(struct dlm_ls *ls)
                case DLM_MSG_CANCEL:
                        hold_lkb(lkb);
                        ls->ls_stub_ms.m_type = DLM_MSG_CANCEL_REPLY;
-                       ls->ls_stub_ms.m_result = -DLM_ECANCEL;
+                       ls->ls_stub_ms.m_result = stub_cancel_result;
                        ls->ls_stub_ms.m_flags = lkb->lkb_flags;
                        _receive_cancel_reply(lkb, &ls->ls_stub_ms);
                        dlm_put_lkb(lkb);
                        break;
 
                default:
-                       log_error(ls, "invalid lkb wait_type %d",
-                                 lkb->lkb_wait_type);
+                       log_error(ls, "invalid lkb wait_type %d %d",
+                                 lkb->lkb_wait_type, wait_type);
                }
                schedule();
        }