[Ocfs2-devel] [PATCH 15/26] ocfs2/dlm: Refactor dlm_clean_master_list()

[Sunil Mushran]

Mainline commit c2cd4a44333034203cb198915e2b75c3227d41bf

This patch refactors dlm_clean_master_list() so as to make it
easier to convert the mle list to a hash.

Signed-off-by: Sunil Mushran <sunil.mushran at oracle.com>
Signed-off-by: Mark Fasheh <mfasheh at suse.com>
---
 fs/ocfs2/dlm/dlmmaster.c |  148 ++++++++++++++++++++++++++-------------------
 1 files changed, 85 insertions(+), 63 deletions(-)

diff --git a/fs/ocfs2/dlm/dlmmaster.c b/fs/ocfs2/dlm/dlmmaster.c
index c388d21..cde4153 100644
--- a/fs/ocfs2/dlm/dlmmaster.c
+++ b/fs/ocfs2/dlm/dlmmaster.c
@@ -3207,12 +3207,87 @@ static int dlm_add_migration_mle(struct dlm_ctxt *dlm,
 	return ret;
 }
 
+/*
+ * Sets the owner of the lockres, associated to the mle, to UNKNOWN
+ */
+static struct dlm_lock_resource *dlm_reset_mleres_owner(struct dlm_ctxt *dlm,
+					struct dlm_master_list_entry *mle)
+{
+	struct dlm_lock_resource *res;
+	unsigned int hash;
+
+	/* Find the lockres associated to the mle and set its owner to UNK */
+	hash = dlm_lockid_hash(mle->u.mlename.name, mle->u.mlename.len);
+	res = __dlm_lookup_lockres(dlm, mle->u.mlename.name, mle->u.mlename.len,
+				   hash);
+	if (res) {
+		spin_unlock(&dlm->master_lock);
+
+		/* move lockres onto recovery list */
+		spin_lock(&res->spinlock);
+		dlm_set_lockres_owner(dlm, res, DLM_LOCK_RES_OWNER_UNKNOWN);
+		dlm_move_lockres_to_recovery_list(dlm, res);
+		spin_unlock(&res->spinlock);
+		dlm_lockres_put(res);
+
+		/* about to get rid of mle, detach from heartbeat */
+		__dlm_mle_detach_hb_events(dlm, mle);
+
+		/* dump the mle */
+		spin_lock(&dlm->master_lock);
+		__dlm_put_mle(mle);
+		spin_unlock(&dlm->master_lock);
+	}
+
+	return res;
+}
+
+static void dlm_clean_migration_mle(struct dlm_ctxt *dlm,
+				    struct dlm_master_list_entry *mle)
+{
+	__dlm_mle_detach_hb_events(dlm, mle);
+
+	spin_lock(&mle->spinlock);
+	__dlm_unlink_mle(dlm, mle);
+	atomic_set(&mle->woken, 1);
+	spin_unlock(&mle->spinlock);
+
+	wake_up(&mle->wq);
+}
+
+static void dlm_clean_block_mle(struct dlm_ctxt *dlm,
+				struct dlm_master_list_entry *mle, u8 dead_node)
+{
+	int bit;
+
+	BUG_ON(mle->type != DLM_MLE_BLOCK);
+
+	spin_lock(&mle->spinlock);
+	bit = find_next_bit(mle->maybe_map, O2NM_MAX_NODES, 0);
+	if (bit != dead_node) {
+		mlog(0, "mle found, but dead node %u would not have been "
+		     "master\n", dead_node);
+		spin_unlock(&mle->spinlock);
+	} else {
+		/* Must drop the refcount by one since the assert_master will
+		 * never arrive. This may result in the mle being unlinked and
+		 * freed, but there may still be a process waiting in the
+		 * dlmlock path which is fine. */
+		mlog(0, "node %u was expected master\n", dead_node);
+		atomic_set(&mle->woken, 1);
+		spin_unlock(&mle->spinlock);
+		wake_up(&mle->wq);
+
+		/* Do not need events any longer, so detach from heartbeat */
+		__dlm_mle_detach_hb_events(dlm, mle);
+		__dlm_put_mle(mle);
+	}
+}
 
 void dlm_clean_master_list(struct dlm_ctxt *dlm, u8 dead_node)
 {
 	struct dlm_master_list_entry *mle, *next;
 	struct dlm_lock_resource *res;
-	unsigned int hash;
 
 	mlog_entry("dlm=%s, dead node=%u\n", dlm->name, dead_node);
 top:
@@ -3236,30 +3311,7 @@ top:
 		 * need to clean up if the dead node would have
 		 * been the master. */
 		if (mle->type == DLM_MLE_BLOCK) {
-			int bit;
-
-			spin_lock(&mle->spinlock);
-			bit = find_next_bit(mle->maybe_map, O2NM_MAX_NODES, 0);
-			if (bit != dead_node) {
-				mlog(0, "mle found, but dead node %u would "
-				     "not have been master\n", dead_node);
-				spin_unlock(&mle->spinlock);
-			} else {
-				/* must drop the refcount by one since the
-				 * assert_master will never arrive.  this
-				 * may result in the mle being unlinked and
-				 * freed, but there may still be a process
-				 * waiting in the dlmlock path which is fine. */
-				mlog(0, "node %u was expected master\n",
-				     dead_node);
-				atomic_set(&mle->woken, 1);
-				spin_unlock(&mle->spinlock);
-				wake_up(&mle->wq);
-				/* do not need events any longer, so detach 
-				 * from heartbeat */
-				__dlm_mle_detach_hb_events(dlm, mle);
-				__dlm_put_mle(mle);
-			}
+			dlm_clean_block_mle(dlm, mle, dead_node);
 			continue;
 		}
 
@@ -3280,51 +3332,21 @@ top:
 
 		/* if we have reached this point, this mle needs to
 		 * be removed from the list and freed. */
-
-		/* remove from the list early.  NOTE: unlinking
-		 * list_head while in list_for_each_safe */
-		__dlm_mle_detach_hb_events(dlm, mle);
-		spin_lock(&mle->spinlock);
-		__dlm_unlink_mle(dlm, mle);
-		atomic_set(&mle->woken, 1);
-		spin_unlock(&mle->spinlock);
-		wake_up(&mle->wq);
+		dlm_clean_migration_mle(dlm, mle);
 
 		mlog(0, "%s: node %u died during migration from "
 		     "%u to %u!\n", dlm->name, dead_node,
 		     mle->master, mle->new_master);
-		/* if there is a lockres associated with this
-	 	 * mle, find it and set its owner to UNKNOWN */
-		hash = dlm_lockid_hash(mle->u.mlename.name, mle->u.mlename.len);
-		res = __dlm_lookup_lockres(dlm, mle->u.mlename.name,
-					   mle->u.mlename.len, hash);
-		if (res) {
-			/* unfortunately if we hit this rare case, our
-		 	 * lock ordering is messed.  we need to drop
-		 	 * the master lock so that we can take the
-		  	 * lockres lock, meaning that we will have to
-			 * restart from the head of list. */
-			spin_unlock(&dlm->master_lock);
-
-			/* move lockres onto recovery list */
-			spin_lock(&res->spinlock);
-			dlm_set_lockres_owner(dlm, res,
-				      	DLM_LOCK_RES_OWNER_UNKNOWN);
-			dlm_move_lockres_to_recovery_list(dlm, res);
-			spin_unlock(&res->spinlock);
-			dlm_lockres_put(res);
-
-			/* about to get rid of mle, detach from heartbeat */
-			__dlm_mle_detach_hb_events(dlm, mle);
-
-			/* dump the mle */
-			spin_lock(&dlm->master_lock);
-			__dlm_put_mle(mle);
-			spin_unlock(&dlm->master_lock);
 
+		/* If we find a lockres associated with the mle, we've
+		 * hit this rare case that messes up our lock ordering.
+		 * If so, we need to drop the master lock so that we can
+		 * take the lockres lock, meaning that we will have to
+		 * restart from the head of list. */
+		res = dlm_reset_mleres_owner(dlm, mle);
+		if (res)
 			/* restart */
 			goto top;
-		}
 
 		/* this may be the last reference */
 		__dlm_put_mle(mle);
-- 
1.5.6.3