dlm_controld: fix plock dev_write no op

When a plock unlock is received due to the file being closed (the CLOSE flag is set), we should not write an unlock result back to the kernel. If we do, the kernel, which does not expect a reply, will report the error "dev_write no op".

In cases where dlm_controld encounters and error handling the unlock operation, it was writing the error result back to the kernel, even though the unlock was flagged with CLOSE. The fix is to check for the CLOSE flag and skip writing the error result, as we do with normal results.

This problem is especially visible when using flocks (not plocks). This is because the kernel generates extraneous plock unlock requests when files are closed with flocks. Because dlm_controld finds no plocks on the files, it replies to the kernel with an error, rather than skipping the reply to do CLOSE.

bz 731775

Signed-off-by David Teigland <[email protected]>

---
 group/dlm_controld/plock.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

group/dlm_controld/plock.c +4 -2

index 6d5dea8..556993b 100644
@@ -1583,8 +1583,10 @@ void process_plocks(int ci)
 	return;
 
  fail:
-	info.rv = rv;
-	rv = write(plock_device_fd, &info, sizeof(info));
+	if (!(info.flags & DLM_PLOCK_FL_CLOSE)) {
+		info.rv = rv;
+		rv = write(plock_device_fd, &info, sizeof(info));
+	}
 }
 
 void process_saved_plocks(struct lockspace *ls)