fs: implement flush function

Once we have caching in file functions we need a way to sync
the the underlying devices.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

2 files changed, 31 insertions, 0 deletions

diff --git a/fs/devfs.c b/fs/devfs.c
index ddb3447673..f82fdddbc2 100644
--- a/fs/devfs.c
+++ b/fs/devfs.c
@@ -169,6 +169,16 @@ static int devfs_close(struct device_d *_dev, FILE *f)
 	return 0;
 }
 
+static int devfs_flush(struct device_d *_dev, FILE *f)
+{
+	struct cdev *cdev = f->inode;
+
+	if (cdev->ops->flush)
+		return cdev->ops->flush(cdev);
+
+	return 0;
+}
+
 static int partition_ioctl(struct cdev *cdev, int request, void *buf)
 {
 	size_t offset;
@@ -287,6 +297,7 @@ static struct fs_driver_d devfs_driver = {
 	.lseek     = devfs_lseek,
 	.open      = devfs_open,
 	.close     = devfs_close,
+	.flush     = devfs_flush,
 	.ioctl     = devfs_ioctl,
 	.opendir   = devfs_opendir,
 	.readdir   = devfs_readdir,
diff --git a/fs/fs.c b/fs/fs.c
index f684d45583..059f67a19f 100644
--- a/fs/fs.c
+++ b/fs/fs.c
@@ -536,6 +536,26 @@ ssize_t write(int fd, const void *buf, size_t count)
 }
 EXPORT_SYMBOL(write);
 
+int flush(int fd)
+{
+	struct device_d *dev;
+	struct fs_driver_d *fsdrv;
+	FILE *f = &files[fd];
+
+	if (check_fd(fd))
+		return errno;
+
+	dev = f->dev;
+
+	fsdrv = (struct fs_driver_d *)dev->driver->type_data;
+	if (fsdrv->flush)
+		errno = fsdrv->flush(dev, f);
+	else
+		errno = 0;
+
+	return errno;
+}
+
 off_t lseek(int fildes, off_t offset, int whence)
 {
 	struct device_d *dev;