dlm: send reply before bast

When the lock master processes a successful operation (request,
convert, cancel, or unlock), it will process the effects of the
change before sending the reply for the operation.  The "effects"
of the operation are:

- blocking callbacks (basts) for any newly granted locks
- waiting or converting locks that can now be granted

The cast is queued on the local node when the reply from the lock
master is received.  This means that a lock holder can receive a
bast for a lock mode that is doesn't yet know has been granted.

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

1 files changed, 84 insertions, 26 deletions

diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c
index e08ea93432bc..d0e43a3da887 100644
--- a/fs/dlm/lock.c
+++ b/fs/dlm/lock.c
@@ -2280,20 +2280,30 @@ static int do_request(struct dlm_rsb *r, struct dlm_lkb *lkb)
         if (can_be_queued(lkb)) {
                 error = -EINPROGRESS;
                 add_lkb(r, lkb, DLM_LKSTS_WAITING);
-                send_blocking_asts(r, lkb);
                 add_timeout(lkb);
                 goto out;
         }
 
         error = -EAGAIN;
-        if (force_blocking_asts(lkb))
-                send_blocking_asts_all(r, lkb);
         queue_cast(r, lkb, -EAGAIN);
-
  out:
         return error;
 }
 
+static void do_request_effects(struct dlm_rsb *r, struct dlm_lkb *lkb,
+                               int error)
+{
+        switch (error) {
+        case -EAGAIN:
+                if (force_blocking_asts(lkb))
+                        send_blocking_asts_all(r, lkb);
+                break;
+        case -EINPROGRESS:
+                send_blocking_asts(r, lkb);
+                break;
+        }
+}
+
 static int do_convert(struct dlm_rsb *r, struct dlm_lkb *lkb)
 {
         int error = 0;
@@ -2304,7 +2314,6 @@ static int do_convert(struct dlm_rsb *r, struct dlm_lkb *lkb)
         if (can_be_granted(r, lkb, 1, &deadlk)) {
                 grant_lock(r, lkb);
                 queue_cast(r, lkb, 0);
-                grant_pending_locks(r);
                 goto out;
         }
 
@@ -2334,7 +2343,6 @@ static int do_convert(struct dlm_rsb *r, struct dlm_lkb *lkb)
                 if (_can_be_granted(r, lkb, 1)) {
                         grant_lock(r, lkb);
                         queue_cast(r, lkb, 0);
-                        grant_pending_locks(r);
                         goto out;
                 }
                 /* else fall through and move to convert queue */
@@ -2344,28 +2352,47 @@ static int do_convert(struct dlm_rsb *r, struct dlm_lkb *lkb)
                 error = -EINPROGRESS;
                 del_lkb(r, lkb);
                 add_lkb(r, lkb, DLM_LKSTS_CONVERT);
-                send_blocking_asts(r, lkb);
                 add_timeout(lkb);
                 goto out;
         }
 
         error = -EAGAIN;
-        if (force_blocking_asts(lkb))
-                send_blocking_asts_all(r, lkb);
         queue_cast(r, lkb, -EAGAIN);
-
  out:
         return error;
 }
 
+static void do_convert_effects(struct dlm_rsb *r, struct dlm_lkb *lkb,
+                               int error)
+{
+        switch (error) {
+        case 0:
+                grant_pending_locks(r);
+                /* grant_pending_locks also sends basts */
+                break;
+        case -EAGAIN:
+                if (force_blocking_asts(lkb))
+                        send_blocking_asts_all(r, lkb);
+                break;
+        case -EINPROGRESS:
+                send_blocking_asts(r, lkb);
+                break;
+        }
+}
+
 static int do_unlock(struct dlm_rsb *r, struct dlm_lkb *lkb)
 {
         remove_lock(r, lkb);
         queue_cast(r, lkb, -DLM_EUNLOCK);
-        grant_pending_locks(r);
         return -DLM_EUNLOCK;
 }
 
+static void do_unlock_effects(struct dlm_rsb *r, struct dlm_lkb *lkb,
+                              int error)
+{
+        grant_pending_locks(r);
+}
+
 /* returns: 0 did nothing, -DLM_ECANCEL canceled lock */
  
 static int do_cancel(struct dlm_rsb *r, struct dlm_lkb *lkb)
@@ -2375,12 +2402,18 @@ static int do_cancel(struct dlm_rsb *r, struct dlm_lkb *lkb)
         error = revert_lock(r, lkb);
         if (error) {
                 queue_cast(r, lkb, -DLM_ECANCEL);
-                grant_pending_locks(r);
                 return -DLM_ECANCEL;
         }
         return 0;
 }
 
+static void do_cancel_effects(struct dlm_rsb *r, struct dlm_lkb *lkb,
+                              int error)
+{
+        if (error)
+                grant_pending_locks(r);
+}
+
 /*
  * Four stage 3 varieties:
  * _request_lock(), _convert_lock(), _unlock_lock(), _cancel_lock()
@@ -2402,11 +2435,15 @@ static int _request_lock(struct dlm_rsb *r, struct dlm_lkb *lkb)
                 goto out;
         }
 
-        if (is_remote(r))
+        if (is_remote(r)) {
                 /* receive_request() calls do_request() on remote node */
                 error = send_request(r, lkb);
-        else
+        } else {
                 error = do_request(r, lkb);
+                /* for remote locks the request_reply is sent
+                   between do_request and do_request_effects */
+                do_request_effects(r, lkb, error);
+        }
  out:
         return error;
 }
@@ -2417,11 +2454,15 @@ static int _convert_lock(struct dlm_rsb *r, struct dlm_lkb *lkb)
 {
         int error;
 
-        if (is_remote(r))
+        if (is_remote(r)) {
                 /* receive_convert() calls do_convert() on remote node */
                 error = send_convert(r, lkb);
-        else
+        } else {
                 error = do_convert(r, lkb);
+                /* for remote locks the convert_reply is sent
+                   between do_convert and do_convert_effects */
+                do_convert_effects(r, lkb, error);
+        }
 
         return error;
 }
@@ -2432,11 +2473,15 @@ static int _unlock_lock(struct dlm_rsb *r, struct dlm_lkb *lkb)
 {
         int error;
 
-        if (is_remote(r))
+        if (is_remote(r)) {
                 /* receive_unlock() calls do_unlock() on remote node */
                 error = send_unlock(r, lkb);
-        else
+        } else {
                 error = do_unlock(r, lkb);
+                /* for remote locks the unlock_reply is sent
+                   between do_unlock and do_unlock_effects */
+                do_unlock_effects(r, lkb, error);
+        }
 
         return error;
 }
@@ -2447,11 +2492,15 @@ static int _cancel_lock(struct dlm_rsb *r, struct dlm_lkb *lkb)
 {
         int error;
 
-        if (is_remote(r))
+        if (is_remote(r)) {
                 /* receive_cancel() calls do_cancel() on remote node */
                 error = send_cancel(r, lkb);
-        else
+        } else {
                 error = do_cancel(r, lkb);
+                /* for remote locks the cancel_reply is sent
+                   between do_cancel and do_cancel_effects */
+                do_cancel_effects(r, lkb, error);
+        }
 
         return error;
 }
@@ -3191,6 +3240,7 @@ static void receive_request(struct dlm_ls *ls, struct dlm_message *ms)
         attach_lkb(r, lkb);
         error = do_request(r, lkb);
         send_request_reply(r, lkb, error);
+        do_request_effects(r, lkb, error);
 
         unlock_rsb(r);
         put_rsb(r);
@@ -3226,15 +3276,19 @@ static void receive_convert(struct dlm_ls *ls, struct dlm_message *ms)
                 goto out;
 
         receive_flags(lkb, ms);
+
         error = receive_convert_args(ls, lkb, ms);
-        if (error)
-                goto out_reply;
+        if (error) {
+                send_convert_reply(r, lkb, error);
+                goto out;
+        }
+
         reply = !down_conversion(lkb);
 
         error = do_convert(r, lkb);
- out_reply:
         if (reply)
                 send_convert_reply(r, lkb, error);
+        do_convert_effects(r, lkb, error);
  out:
         unlock_rsb(r);
         put_rsb(r);
@@ -3266,13 +3320,16 @@ static void receive_unlock(struct dlm_ls *ls, struct dlm_message *ms)
                 goto out;
 
         receive_flags(lkb, ms);
+
         error = receive_unlock_args(ls, lkb, ms);
-        if (error)
-                goto out_reply;
+        if (error) {
+                send_unlock_reply(r, lkb, error);
+                goto out;
+        }
 
         error = do_unlock(r, lkb);
- out_reply:
         send_unlock_reply(r, lkb, error);
+        do_unlock_effects(r, lkb, error);
  out:
         unlock_rsb(r);
         put_rsb(r);
@@ -3307,6 +3364,7 @@ static void receive_cancel(struct dlm_ls *ls, struct dlm_message *ms)
 
         error = do_cancel(r, lkb);
         send_cancel_reply(r, lkb, error);
+        do_cancel_effects(r, lkb, error);
  out:
         unlock_rsb(r);
         put_rsb(r);