sanitize vfs_fsync calling conventions

Now that the last user passing a NULL file pointer is gone we can remove
the redundant dentry argument and associated hacks inside vfs_fsynmc_range.

The next step will be removig the dentry argument from ->fsync, but given
the luck with the last round of method prototype changes I'd rather
defer this until after the main merge window.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/drivers/usb/gadget/storage_common.c b/drivers/usb/gadget/storage_common.c
index 868d8ee..04c462f 100644
--- a/drivers/usb/gadget/storage_common.c
+++ b/drivers/usb/gadget/storage_common.c
@@ -654,7 +654,7 @@
 
 	if (curlun->ro || !filp)
 		return 0;
-	return vfs_fsync(filp, filp->f_path.dentry, 1);
+	return vfs_fsync(filp, 1);
 }
 
 static void store_cdrom_address(u8 *dest, int msf, u32 addr)