Don't mix and match [a]sync read/write operations

Hopefully prevents deadlocking when async writes saturate the thread pool when
a read operation occurs.

1 files changed, 13 insertions, 6 deletions

diff --git a/netfs/fuse/fuseFiles.cpp b/netfs/fuse/fuseFiles.cpp
index 858a0a9..e56ce0b 100644
--- a/netfs/fuse/fuseFiles.cpp
+++ b/netfs/fuse/fuseFiles.cpp
@@ -147,14 +147,21 @@ int
 FuseApp::read(const char *, char * buf, size_t s, off_t o, struct fuse_file_info * fi)
 {
 	try {
+		auto cpy = [buf](const auto && data) {
+			memcpy(buf, &data.front(), data.size());
+			return data.size();
+		};
 		auto of = getProxy<OpenFilePtr>(fi->fh);
 		auto remote = of->remote;
-		auto data = (fcr->Async) ?
-			waitOnWriteRangeAndThen<Buffer>(s, o, of, [o, s, &remote](const auto &){
-				return remote->read(o, s);
-			}) : remote->read(o, s);
-		memcpy(buf, &data.front(), data.size());
-		return data.size();
+		if (fcr->Async) {
+			auto p = waitOnWriteRangeAndThen<std::future<Buffer>>(s, o, of, [o, s, &remote](const auto &){
+				return remote->readAsync(o, s);
+			});
+			return cpy(p.get());
+		}
+		else {
+			return cpy(remote->read(o, s));
+		}
 	}
 	catch (SystemError & e) {
 		return -e.syserrno;