switch simple cases of fget_light to fdget

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/signalfd.c

@@ -269,13 +269,12 @@ SYSCALL_DEFINE4(signalfd4, int, ufd, sigset_t __user *, user_mask,
 		if (ufd < 0)
 			kfree(ctx);
 	} else {
-		int fput_needed;
-		struct file *file = fget_light(ufd, &fput_needed);
-		if (!file)
+		struct fd f = fdget(ufd);
+		if (!f.file)
 			return -EBADF;
-		ctx = file->private_data;
-		if (file->f_op != &signalfd_fops) {
-			fput_light(file, fput_needed);
+		ctx = f.file->private_data;
+		if (f.file->f_op != &signalfd_fops) {
+			fdput(f);
 			return -EINVAL;
 		}
 		spin_lock_irq(&current->sighand->siglock);
@@ -283,7 +282,7 @@ SYSCALL_DEFINE4(signalfd4, int, ufd, sigset_t __user *, user_mask,
 		spin_unlock_irq(&current->sighand->siglock);
 
 		wake_up(&current->sighand->signalfd_wqh);
-		fput_light(file, fput_needed);
+		fdput(f);
 	}
 
 	return ufd;