dlm: clear defunct cancel state

When a conversion completes successfully and finds that a cancel
of the convert is still in progress (which is now a moot point),
preemptively clear the state associated with outstanding cancel.
That state could cause a subsequent conversion to be ignored.

Also, improve the consistency and content of error and debug
messages in this area.

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

1 files changed, 45 insertions, 8 deletions

diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c
index 01e7d39c5fba..8cb92046a584 100644
--- a/fs/dlm/lock.c
+++ b/fs/dlm/lock.c
@@ -835,7 +835,7 @@ static int add_to_waiters(struct dlm_lkb *lkb, int mstype)
                 lkb->lkb_wait_count++;
                 hold_lkb(lkb);
 
-                log_debug(ls, "add overlap %x cur %d new %d count %d flags %x",
+                log_debug(ls, "addwait %x cur %d overlap %d count %d f %x",
                           lkb->lkb_id, lkb->lkb_wait_type, mstype,
                           lkb->lkb_wait_count, lkb->lkb_flags);
                 goto out;
@@ -851,7 +851,7 @@ static int add_to_waiters(struct dlm_lkb *lkb, int mstype)
         list_add(&lkb->lkb_wait_reply, &ls->ls_waiters);
  out:
         if (error)
-                log_error(ls, "add_to_waiters %x error %d flags %x %d %d %s",
+                log_error(ls, "addwait error %x %d flags %x %d %d %s",
                           lkb->lkb_id, error, lkb->lkb_flags, mstype,
                           lkb->lkb_wait_type, lkb->lkb_resource->res_name);
         mutex_unlock(&ls->ls_waiters_mutex);
@@ -863,23 +863,55 @@ static int add_to_waiters(struct dlm_lkb *lkb, int mstype)
    request reply on the requestqueue) between dlm_recover_waiters_pre() which
    set RESEND and dlm_recover_waiters_post() */
 
-static int _remove_from_waiters(struct dlm_lkb *lkb, int mstype)
+static int _remove_from_waiters(struct dlm_lkb *lkb, int mstype,
+                                struct dlm_message *ms)
 {
         struct dlm_ls *ls = lkb->lkb_resource->res_ls;
         int overlap_done = 0;
 
         if (is_overlap_unlock(lkb) && (mstype == DLM_MSG_UNLOCK_REPLY)) {
+                log_debug(ls, "remwait %x unlock_reply overlap", lkb->lkb_id);
                 lkb->lkb_flags &= ~DLM_IFL_OVERLAP_UNLOCK;
                 overlap_done = 1;
                 goto out_del;
         }
 
         if (is_overlap_cancel(lkb) && (mstype == DLM_MSG_CANCEL_REPLY)) {
+                log_debug(ls, "remwait %x cancel_reply overlap", lkb->lkb_id);
                 lkb->lkb_flags &= ~DLM_IFL_OVERLAP_CANCEL;
                 overlap_done = 1;
                 goto out_del;
         }
 
+        /* Cancel state was preemptively cleared by a successful convert,
+           see next comment, nothing to do. */
+
+        if ((mstype == DLM_MSG_CANCEL_REPLY) &&
+            (lkb->lkb_wait_type != DLM_MSG_CANCEL)) {
+                log_debug(ls, "remwait %x cancel_reply wait_type %d",
+                          lkb->lkb_id, lkb->lkb_wait_type);
+                return -1;
+        }
+
+        /* Remove for the convert reply, and premptively remove for the
+           cancel reply.  A convert has been granted while there's still
+           an outstanding cancel on it (the cancel is moot and the result
+           in the cancel reply should be 0).  We preempt the cancel reply
+           because the app gets the convert result and then can follow up
+           with another op, like convert.  This subsequent op would see the
+           lingering state of the cancel and fail with -EBUSY. */
+
+        if ((mstype == DLM_MSG_CONVERT_REPLY) &&
+            (lkb->lkb_wait_type == DLM_MSG_CONVERT) &&
+            is_overlap_cancel(lkb) && ms && !ms->m_result) {
+                log_debug(ls, "remwait %x convert_reply zap overlap_cancel",
+                          lkb->lkb_id);
+                lkb->lkb_wait_type = 0;
+                lkb->lkb_flags &= ~DLM_IFL_OVERLAP_CANCEL;
+                lkb->lkb_wait_count--;
+                goto out_del;
+        }
+
         /* N.B. type of reply may not always correspond to type of original
            msg due to lookup->request optimization, verify others? */
 
@@ -888,8 +920,8 @@ static int _remove_from_waiters(struct dlm_lkb *lkb, int mstype)
                 goto out_del;
         }
 
-        log_error(ls, "remove_from_waiters lkid %x flags %x types %d %d",
-                  lkb->lkb_id, lkb->lkb_flags, mstype, lkb->lkb_wait_type);
+        log_error(ls, "remwait error %x reply %d flags %x no wait_type",
+                  lkb->lkb_id, mstype, lkb->lkb_flags);
         return -1;
 
  out_del:
@@ -899,7 +931,7 @@ static int _remove_from_waiters(struct dlm_lkb *lkb, int mstype)
            this would happen */
 
         if (overlap_done && lkb->lkb_wait_type) {
-                log_error(ls, "remove_from_waiters %x reply %d give up on %d",
+                log_error(ls, "remwait error %x reply %d wait_type %d overlap",
                           lkb->lkb_id, mstype, lkb->lkb_wait_type);
                 lkb->lkb_wait_count--;
                 lkb->lkb_wait_type = 0;
@@ -921,7 +953,7 @@ static int remove_from_waiters(struct dlm_lkb *lkb, int mstype)
         int error;
 
         mutex_lock(&ls->ls_waiters_mutex);
-        error = _remove_from_waiters(lkb, mstype);
+        error = _remove_from_waiters(lkb, mstype, NULL);
         mutex_unlock(&ls->ls_waiters_mutex);
         return error;
 }
@@ -936,7 +968,7 @@ static int remove_from_waiters_ms(struct dlm_lkb *lkb, struct dlm_message *ms)
 
         if (ms != &ls->ls_stub_ms)
                 mutex_lock(&ls->ls_waiters_mutex);
-        error = _remove_from_waiters(lkb, ms->m_type);
+        error = _remove_from_waiters(lkb, ms->m_type, ms);
         if (ms != &ls->ls_stub_ms)
                 mutex_unlock(&ls->ls_waiters_mutex);
         return error;
@@ -2083,6 +2115,11 @@ static int validate_lock_args(struct dlm_ls *ls, struct dlm_lkb *lkb,
         lkb->lkb_timeout_cs = args->timeout;
         rv = 0;
  out:
+        if (rv)
+                log_debug(ls, "validate_lock_args %d %x %x %x %d %d %s",
+                          rv, lkb->lkb_id, lkb->lkb_flags, args->flags,
+                          lkb->lkb_status, lkb->lkb_wait_type,
+                          lkb->lkb_resource->res_name);
         return rv;
 }