[Cluster-devel] [RFC PATCH dlm/next 1/2] fs: dlm: provide some lockless functionality

[Alexander Aring]

This patch provides some lockless functionality for the central dlm
locking logic. It can be used internally to call central dlm locking
logic functionality if the necessary resource lock is already held.

Signed-off-by: Alexander Aring <aahringo at redhat.com>
---
 fs/dlm/lock.c | 72 ++++++++++++++++++++++++++++++++++-----------------
 1 file changed, 48 insertions(+), 24 deletions(-)

diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c
index 3d4eeab213da..c419a5b5b7c0 100644
--- a/fs/dlm/lock.c
+++ b/fs/dlm/lock.c
@@ -4641,25 +4641,33 @@ static void __receive_convert_reply(struct dlm_rsb *r, struct dlm_lkb *lkb,
 	}
 }
 
-static void _receive_convert_reply(struct dlm_lkb *lkb, struct dlm_message *ms)
+static void _receive_convert_reply_lockless(struct dlm_lkb *lkb,
+					    struct dlm_message *ms,
+					    struct dlm_rsb *r)
 {
-	struct dlm_rsb *r = lkb->lkb_resource;
 	int error;
 
-	hold_rsb(r);
-	lock_rsb(r);
-
 	error = validate_message(lkb, ms);
 	if (error)
-		goto out;
+		return;
 
 	/* stub reply can happen with waiters_mutex held */
 	error = remove_from_waiters_ms(lkb, ms);
 	if (error)
-		goto out;
+		return;
 
 	__receive_convert_reply(r, lkb, ms);
- out:
+}
+
+static void _receive_convert_reply(struct dlm_lkb *lkb, struct dlm_message *ms)
+{
+	struct dlm_rsb *r = lkb->lkb_resource;
+
+	hold_rsb(r);
+	lock_rsb(r);
+
+	_receive_convert_reply_lockless(lkb, ms, r);
+
 	unlock_rsb(r);
 	put_rsb(r);
 }
@@ -4678,22 +4686,20 @@ static int receive_convert_reply(struct dlm_ls *ls, struct dlm_message *ms)
 	return 0;
 }
 
-static void _receive_unlock_reply(struct dlm_lkb *lkb, struct dlm_message *ms)
+static void _receive_unlock_reply_lockless(struct dlm_lkb *lkb,
+					   struct dlm_message *ms,
+					   struct dlm_rsb *r)
 {
-	struct dlm_rsb *r = lkb->lkb_resource;
 	int error;
 
-	hold_rsb(r);
-	lock_rsb(r);
-
 	error = validate_message(lkb, ms);
 	if (error)
-		goto out;
+		return;
 
 	/* stub reply can happen with waiters_mutex held */
 	error = remove_from_waiters_ms(lkb, ms);
 	if (error)
-		goto out;
+		return;
 
 	/* this is the value returned from do_unlock() on the master */
 
@@ -4709,7 +4715,17 @@ static void _receive_unlock_reply(struct dlm_lkb *lkb, struct dlm_message *ms)
 		log_error(r->res_ls, "receive_unlock_reply %x error %d",
 			  lkb->lkb_id, ms->m_result);
 	}
- out:
+}
+
+static void _receive_unlock_reply(struct dlm_lkb *lkb, struct dlm_message *ms)
+{
+	struct dlm_rsb *r = lkb->lkb_resource;
+
+	hold_rsb(r);
+	lock_rsb(r);
+
+	_receive_unlock_reply_lockless(lkb, ms, r);
+
 	unlock_rsb(r);
 	put_rsb(r);
 }
@@ -4728,22 +4744,20 @@ static int receive_unlock_reply(struct dlm_ls *ls, struct dlm_message *ms)
 	return 0;
 }
 
-static void _receive_cancel_reply(struct dlm_lkb *lkb, struct dlm_message *ms)
+static void _receive_cancel_reply_lockless(struct dlm_lkb *lkb,
+					   struct dlm_message *ms,
+					   struct dlm_rsb *r)
 {
-	struct dlm_rsb *r = lkb->lkb_resource;
 	int error;
 
-	hold_rsb(r);
-	lock_rsb(r);
-
 	error = validate_message(lkb, ms);
 	if (error)
-		goto out;
+		return;
 
 	/* stub reply can happen with waiters_mutex held */
 	error = remove_from_waiters_ms(lkb, ms);
 	if (error)
-		goto out;
+		return;
 
 	/* this is the value returned from do_cancel() on the master */
 
@@ -4759,7 +4773,17 @@ static void _receive_cancel_reply(struct dlm_lkb *lkb, struct dlm_message *ms)
 		log_error(r->res_ls, "receive_cancel_reply %x error %d",
 			  lkb->lkb_id, ms->m_result);
 	}
- out:
+}
+
+static void _receive_cancel_reply(struct dlm_lkb *lkb, struct dlm_message *ms)
+{
+	struct dlm_rsb *r = lkb->lkb_resource;
+
+	hold_rsb(r);
+	lock_rsb(r);
+
+	_receive_cancel_reply_lockless(lkb, ms, r);
+
 	unlock_rsb(r);
 	put_rsb(r);
 }
-- 
2.27.0