devices: Ignore O_DIRECT in 9p and fs devices

Specifying O_DIRECT in the 9p device doesn't actually work correctly and
leads to an error.  O_DIRECT handling in the fs device works correctly
but also makes it look much worse in disk I/O benchmarks because the
block device gets the benefit of the host cache while the fs device
depends on the performance of the actual storage device.

BUG=none
TEST=`tast run vm.Fio.*`

Change-Id: I738e4032081e331ef956c9d4c33616607e403d86
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/2093967
Commit-Queue: Chirantan Ekbote <chirantan@chromium.org>
Tested-by: Chirantan Ekbote <chirantan@chromium.org>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Dylan Reid <dgreid@chromium.org>
Reviewed-by: Daniel Verkamp <dverkamp@chromium.org>

1 files changed, 3 insertions, 2 deletions

diff --git a/devices/src/virtio/fs/passthrough.rs b/devices/src/virtio/fs/passthrough.rs
index bdc1c6f..d23009b 100644
--- a/devices/src/virtio/fs/passthrough.rs
+++ b/devices/src/virtio/fs/passthrough.rs
@@ -395,7 +395,7 @@ impl PassthroughFs {
             libc::openat(
                 self.proc.as_raw_fd(),
                 pathname.as_ptr(),
-                (flags | libc::O_CLOEXEC) & (!libc::O_NOFOLLOW),
+                (flags | libc::O_CLOEXEC) & !(libc::O_NOFOLLOW | libc::O_DIRECT),
             )
         };
         if fd < 0 {
@@ -965,7 +965,8 @@ impl FileSystem for PassthroughFs {
             libc::openat(
                 data.file.as_raw_fd(),
                 name.as_ptr(),
-                flags as i32 | libc::O_CREAT | libc::O_CLOEXEC | libc::O_NOFOLLOW,
+                (flags as i32 | libc::O_CREAT | libc::O_CLOEXEC | libc::O_NOFOLLOW)
+                    & !libc::O_DIRECT,
                 mode & !(umask & 0o777),
             )
         };