[RFC PATCH 13/35] ovl: readd fsync

[Miklos Szeredi]

Implement stacked fsync().

Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx>
---
 fs/overlayfs/file.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index b98204c1c19c..4417527667ff 100644
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -222,10 +222,30 @@ static ssize_t ovl_write_iter(struct kiocb *iocb, struct iov_iter *iter)
 	return ret;
 }
 
+static int ovl_fsync(struct file *file, loff_t start, loff_t end, int datasync)
+{
+	struct fd real;
+	const struct cred *old_cred;
+	int ret;
+
+	ret = ovl_real_file(file, &real);
+	if (ret)
+		return ret;
+
+	old_cred = ovl_override_creds(file_inode(file)->i_sb);
+	ret = vfs_fsync_range(real.file, start, end, datasync);
+	revert_creds(old_cred);
+
+	fdput(real);
+
+	return ret;
+}
+
 const struct file_operations ovl_file_operations = {
 	.open		= ovl_open,
 	.release	= ovl_release,
 	.llseek		= ovl_llseek,
 	.read_iter	= ovl_read_iter,
 	.write_iter	= ovl_write_iter,
+	.fsync		= ovl_fsync,
 };
-- 
2.14.3