[LTP] [PATCH COMMITTED] tst_device: do sync() before reading test block device stat file

[Li Wang]

To avoid FS deferred IO metadata/cache interferes test result, so we
do sync simply before the tst_dev_bytes_written invocation.

Signed-off-by: Li Wang <liwang@redhat.com>
Cc: Sumit Garg <sumit.garg@linaro.org>
Cc: Yang Xu <xuyang2018.jy@cn.fujitsu.com>
---
 testcases/kernel/syscalls/fdatasync/fdatasync03.c | 2 ++
 testcases/kernel/syscalls/fsync/fsync04.c         | 2 ++
 testcases/kernel/syscalls/sync/sync03.c           | 2 ++
 testcases/kernel/syscalls/syncfs/syncfs01.c       | 2 ++
 4 files changed, 8 insertions(+)

diff --git a/testcases/kernel/syscalls/fdatasync/fdatasync03.c b/testcases/kernel/syscalls/fdatasync/fdatasync03.c
index ee50e75c9..032ac4b58 100644
--- a/testcases/kernel/syscalls/fdatasync/fdatasync03.c
+++ b/testcases/kernel/syscalls/fdatasync/fdatasync03.c
@@ -32,6 +32,8 @@ static void verify_fdatasync(void)
 
 	fd = SAFE_OPEN(FNAME, O_RDWR|O_CREAT, MODE);
 
+	sync();
+
 	tst_dev_bytes_written(tst_device->dev);
 
 	tst_fill_fd(fd, 0, TST_MB, FILE_SIZE_MB);
diff --git a/testcases/kernel/syscalls/fsync/fsync04.c b/testcases/kernel/syscalls/fsync/fsync04.c
index c67fc5692..3c1f45e94 100644
--- a/testcases/kernel/syscalls/fsync/fsync04.c
+++ b/testcases/kernel/syscalls/fsync/fsync04.c
@@ -32,6 +32,8 @@ static void verify_fsync(void)
 
 	fd = SAFE_OPEN(FNAME, O_RDWR|O_CREAT, MODE);
 
+	sync();
+
 	tst_dev_bytes_written(tst_device->dev);
 
 	tst_fill_fd(fd, 0, TST_MB, FILE_SIZE_MB);
diff --git a/testcases/kernel/syscalls/sync/sync03.c b/testcases/kernel/syscalls/sync/sync03.c
index a6f72d2ed..085ccfdeb 100644
--- a/testcases/kernel/syscalls/sync/sync03.c
+++ b/testcases/kernel/syscalls/sync/sync03.c
@@ -32,6 +32,8 @@ static void verify_sync(void)
 
 	fd = SAFE_OPEN(FNAME, O_RDWR|O_CREAT, MODE);
 
+	sync();
+
 	tst_dev_bytes_written(tst_device->dev);
 
 	tst_fill_fd(fd, 0, TST_MB, FILE_SIZE_MB);
diff --git a/testcases/kernel/syscalls/syncfs/syncfs01.c b/testcases/kernel/syscalls/syncfs/syncfs01.c
index 051a19ea6..3cf404450 100644
--- a/testcases/kernel/syscalls/syncfs/syncfs01.c
+++ b/testcases/kernel/syscalls/syncfs/syncfs01.c
@@ -33,6 +33,8 @@ static void verify_syncfs(void)
 
 	fd = SAFE_OPEN(FNAME, O_RDWR|O_CREAT, MODE);
 
+	sync();
+
 	tst_dev_bytes_written(tst_device->dev);
 
 	tst_fill_fd(fd, 0, TST_MB, FILE_SIZE_MB);
-- 
2.20.1