From aeb87efb1ffe2ed425965e2c8e3bbd2bf80947dc Mon Sep 17 00:00:00 2001
From: Zim <zezeozue@google.com>
Date: Thu, 26 Sep 2019 16:06:05 +0100
Subject: [PATCH] Lazily write inode timestamps to FUSE

Before this, the FUSE daemon receives a setattr inode timestamp
request for every write request. This can be crippling for write
performance or read performance during writes especially random
writes where the write back cache does not effectively coagulate
requests.

We now add the MS_LAZYTIME mount flag
(http://man7.org/linux/man-pages/man2/mount.2.html) to lazily flush
the timestamp updates from memory to disk

Test: m
Bug: 135341433
Change-Id: I95a467d5682a325b4099f32634d93ed2921f815e
---
 Utils.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Utils.cpp b/Utils.cpp
index 5e284b2..e5bf33d 100644
--- a/Utils.cpp
+++ b/Utils.cpp
@@ -1023,7 +1023,8 @@ int MountUserFuse(userid_t user_id, const std::string& relative_path,
 
     const int result_int =
         TEMP_FAILURE_RETRY(mount("/dev/fuse", path.c_str(), "fuse",
-                                 MS_NOSUID | MS_NODEV | MS_NOEXEC | MS_NOATIME, opts.c_str()));
+                                 MS_NOSUID | MS_NODEV | MS_NOEXEC | MS_NOATIME | MS_LAZYTIME,
+                                 opts.c_str()));
     if (result_int != 0) {
         PLOG(ERROR) << "Failed to mount " << path;
         return -errno;