[libmultipath] use noflush feature

The patch requires libdevmapper 1.02.11 or later.

The patch is tested on both multipath-tools on git and
multipath-tools-0.4.7-5.2 in RHEL5 beta2 for the following scenario:
   1. prepare 2 physical paths
   2. down (delete) the 1st path
   3. create multipath map with the 2nd path with queue_if_no_path
   4. do I/O on it
   5. down (delete) the 2nd path
   6. up the 1st path
   7. no I/O error should be observed in user space

Jun'ichi Nomura, NEC

diff --git a/libmultipath/devmapper.c b/libmultipath/devmapper.c
index 2ecfba4..ff4a416 100644 (file)
--- a/libmultipath/devmapper.c
+++ b/libmultipath/devmapper.c
@@ -134,6 +134,7 @@ dm_simplecmd (int task, const char *name) {
 
        dm_task_no_open_count(dmt);
        dm_task_skip_lockfs(dmt);       /* for DM_DEVICE_RESUME */
+       dm_task_no_flush(dmt);          /* for DM_DEVICE_SUSPEND/RESUME */
 
        r = dm_task_run (dmt);