From 2192cac634dcd13c3365f4dfeb5f393f4fd9e327 Mon Sep 17 00:00:00 2001
From: Robert Hensing <robert@roberthensing.nl>
Date: Fri, 30 Oct 2020 21:47:34 +0100
Subject: [PATCH] Fix RemoteStore pool deadlock in filterSource etc

---
 src/libstore/remote-store.cc | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/src/libstore/remote-store.cc b/src/libstore/remote-store.cc
index 488270f48..ccbd3bb1d 100644
--- a/src/libstore/remote-store.cc
+++ b/src/libstore/remote-store.cc
@@ -471,9 +471,14 @@ ref<const ValidPathInfo> RemoteStore::addCAToStore(
         worker_proto::write(*this, conn->to, references);
         conn->to << repair;
 
-        conn.withFramedSink([&](Sink & sink) {
-            dump.drainInto(sink);
-        });
+        // The dump source may invoke the store, so we need to make some room.
+        connections->incCapacity();
+        {
+            Finally cleanup([&]() { connections->decCapacity(); });
+            conn.withFramedSink([&](Sink & sink) {
+                dump.drainInto(sink);
+            });
+        }
 
         auto path = parseStorePath(readString(conn->from));
         return readValidPathInfo(conn, path);