Some users want to be very sure that data has gone out to the
device. This needs fsync.
Reported-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Oliver Neukum <oneukum@xxxxxxxx>
---
drivers/usb/class/cdc-wdm.c | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)
diff --git a/drivers/usb/class/cdc-wdm.c b/drivers/usb/class/cdc-wdm.c
index 242f83118208..6ea03c12380c 100644
--- a/drivers/usb/class/cdc-wdm.c
+++ b/drivers/usb/class/cdc-wdm.c
@@ -590,6 +590,33 @@ static ssize_t wdm_read
return rv;
}
+/*
+ * The difference to flush is that we wait forever. If you don't like
+ * that behavior, you need to send a signal.
+ */
+
+static int wdm_fsync(struct file *file, loff_t start, loff_t end, int datasync)
+{
+ struct wdm_device *desc = file->private_data;
+ int rv;
+
+ rv = wait_event_interruptible(desc->wait,
+ !test_bit(WDM_IN_USE, &desc->flags) ||
+ test_bit(WDM_DISCONNECTING, &desc->flags));
+
+ if (test_bit(WDM_DISCONNECTING, &desc->flags))
+ return -ENODEV;
+ if (rv < 0)
+ return -EINTR;
+
+ spin_lock_irq(&desc->iuspin);
+ rv = desc->werr;
+ desc->werr = 0;
+ spin_unlock_irq(&desc->iuspin);
+
+ return usb_translate_errors(rv);
+}
+
static int wdm_flush(struct file *file, fl_owner_t id)
{
struct wdm_device *desc = file->private_data;
@@ -746,6 +773,7 @@ static const struct file_operations wdm_fops = {
.owner = THIS_MODULE,
.read = wdm_read,
.write = wdm_write,
+ .fsync = wdm_fsync,
.open = wdm_open,
.flush = wdm_flush,
.release = wdm_release,
--
2.16.4
