fs: Convert show_fdinfo functions to void

seq_printf functions shouldn't really check the return value.
Checking seq_has_overflowed() occasionally is used instead.

Update vfs documentation.

Link: http://lkml.kernel.org/p/e37e6e7b76acbdcc3bb4ab2a57c8f8ca1ae11b9a.1412031505.git.joe@perches.com

Cc: David S. Miller <davem@davemloft.net>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Joe Perches <joe@perches.com>
[ did a few clean ups ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/fs/proc/fd.c b/fs/proc/fd.c
index e11d7c5..8e5ad83 100644
--- a/fs/proc/fd.c
+++ b/fs/proc/fd.c
@@ -53,7 +53,8 @@
 			   (long long)file->f_pos, f_flags,
 			   real_mount(file->f_path.mnt)->mnt_id);
 		if (file->f_op->show_fdinfo)
-			ret = file->f_op->show_fdinfo(m, file);
+			file->f_op->show_fdinfo(m, file);
+		ret = seq_has_overflowed(m);
 		fput(file);
 	}