From 156ba420c320dfda8cee5d5281c0810490c4be9c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C5=81ukasz=20Magiera?= <magik6k@gmail.com>
Date: Sat, 17 Dec 2022 13:12:33 +0100
Subject: [PATCH] fix: splitstore: Don't deadlock in mpool protector

---
 chain/messagepool/messagepool.go | 8 ++++++--
 node/modules/chain.go            | 2 +-
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/chain/messagepool/messagepool.go b/chain/messagepool/messagepool.go
index 0724f145f..94ae62673 100644
--- a/chain/messagepool/messagepool.go
+++ b/chain/messagepool/messagepool.go
@@ -443,8 +443,12 @@ func New(ctx context.Context, api Provider, ds dtypes.MetadataDS, us stmgr.Upgra
 	return mp, nil
 }
 
-func (mp *MessagePool) ForEachPendingMessage(f func(cid.Cid) error) error {
-	mp.lk.Lock()
+func (mp *MessagePool) TryForEachPendingMessage(f func(cid.Cid) error) error {
+	// avoid deadlocks in splitstore compaction when something else needs to access the blockstore
+	// while holding the mpool lock
+	if !mp.lk.TryLock() {
+		return xerrors.Errorf("mpool TryForEachPendingMessage: could not acquire lock")
+	}
 	defer mp.lk.Unlock()
 
 	for _, mset := range mp.pending {
diff --git a/node/modules/chain.go b/node/modules/chain.go
index 22a1d618a..49418d883 100644
--- a/node/modules/chain.go
+++ b/node/modules/chain.go
@@ -69,7 +69,7 @@ func MessagePool(lc fx.Lifecycle, mctx helpers.MetricsCtx, us stmgr.UpgradeSched
 			return mp.Close()
 		},
 	})
-	protector.AddProtector(mp.ForEachPendingMessage)
+	protector.AddProtector(mp.TryForEachPendingMessage)
 	return mp, nil
 }