[PATCH v5 08/25] fuse: Set direct_io and parallel_direct_writes

[Hanna Czenczek <hreitz@redhat.com>]

In fuse_open(), set these flags:
- direct_io: We probably actually don't want to have the host page cache
  be used for our exports.  QEMU block exports are supposed to represent
  the image as-is (and thus potentially changing).
  This causes a change in iotest 308's reference output.

- parallel_direct_writes: We can (now) cope with parallel writes, so we
  should set this flag.  For some reason, it doesn't seem to make an
  actual performance difference with libfuse, but it does make a
  difference without it, so let's set it.
  (See "fuse: Copy write buffer content before polling" for further
  discussion.)

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Hanna Czenczek <hreitz@redhat.com>
---
 block/export/fuse.c        | 2 ++
 tests/qemu-iotests/308.out | 2 +-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/block/export/fuse.c b/block/export/fuse.c
index 0422cf4b8a..d0e3c6bf61 100644
--- a/block/export/fuse.c
+++ b/block/export/fuse.c
@@ -582,6 +582,8 @@ static void fuse_setattr(fuse_req_t req, fuse_ino_t inode, struct stat *statbuf,
 static void fuse_open(fuse_req_t req, fuse_ino_t inode,
                       struct fuse_file_info *fi)
 {
+    fi->direct_io = true;
+    fi->parallel_direct_writes = true;
     fuse_reply_open(req, fi);
 }
 
diff --git a/tests/qemu-iotests/308.out b/tests/qemu-iotests/308.out
index aa96faab6d..2d7a38d63d 100644
--- a/tests/qemu-iotests/308.out
+++ b/tests/qemu-iotests/308.out
@@ -131,7 +131,7 @@ wrote 65536/65536 bytes at offset 1048576
 
 --- Try growing non-growable export ---
 (OK: Lengths of export and original are the same)
-dd: error writing 'TEST_DIR/t.IMGFMT.fuse': Input/output error
+dd: error writing 'TEST_DIR/t.IMGFMT.fuse': No space left on device
 1+0 records in
 0+0 records out
 
-- 
2.53.0