From 5eb903a509f7b8471ba5365536d00188bbbe70c0 Mon Sep 17 00:00:00 2001
From: Sergio Lopez <slp@redhat.com>
Date: Fri, 20 Mar 2020 17:26:27 +0100
Subject: [PATCH] vhost_user_fs: Add support for FOPEN_CACHE_DIR

Add support for FOPEN_CACHE_DIR, a flag that allows us to tell the
guest that it's safe to cache a directory, introduced in FUSE 7.28.

Signed-off-by: Sergio Lopez <slp@redhat.com>
---
 vhost_user_fs/src/fuse.rs        | 4 ++++
 vhost_user_fs/src/passthrough.rs | 8 +++++++-
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/vhost_user_fs/src/fuse.rs b/vhost_user_fs/src/fuse.rs
index 897e3cfbc..6ddb71468 100644
--- a/vhost_user_fs/src/fuse.rs
+++ b/vhost_user_fs/src/fuse.rs
@@ -55,6 +55,9 @@ const FOPEN_KEEP_CACHE: u32 = 2;
 /// The file is not seekable.
 const FOPEN_NONSEEKABLE: u32 = 4;
 
+/// Allow caching this directory.
+const FOPEN_CACHE_DIR: u32 = 8;
+
 bitflags! {
     /// Options controlling the behavior of files opened by the server in response
     /// to an open or create request.
@@ -62,6 +65,7 @@ bitflags! {
         const DIRECT_IO = FOPEN_DIRECT_IO;
         const KEEP_CACHE = FOPEN_KEEP_CACHE;
         const NONSEEKABLE = FOPEN_NONSEEKABLE;
+        const CACHE_DIR = FOPEN_CACHE_DIR;
     }
 }
 
diff --git a/vhost_user_fs/src/passthrough.rs b/vhost_user_fs/src/passthrough.rs
index 2a1456cd2..f76478b5d 100644
--- a/vhost_user_fs/src/passthrough.rs
+++ b/vhost_user_fs/src/passthrough.rs
@@ -558,7 +558,13 @@ impl PassthroughFs {
                 OpenOptions::DIRECT_IO,
                 flags & (libc::O_DIRECTORY as u32) == 0,
             ),
-            CachePolicy::Always => opts |= OpenOptions::KEEP_CACHE,
+            CachePolicy::Always => {
+                if flags & (libc::O_DIRECTORY as u32) == 0 {
+                    opts |= OpenOptions::KEEP_CACHE;
+                } else {
+                    opts |= OpenOptions::CACHE_DIR;
+                }
+            }
             _ => {}
         };