[libvirt] [test-API][PATCH] managedsave: change the checking method about bypass cache

[hongming]

Check whether the O_DIRECT flag is in use on the managed save file
during the duration of the managed save, since that is the real effect
of the current implementation of the --bypass-cache flag.
---
 repos/managedsave/managedsave.py |   66 +++++++++++++++++++------------------
 1 files changed, 34 insertions(+), 32 deletions(-)

diff --git a/repos/managedsave/managedsave.py b/repos/managedsave/managedsave.py
index 4a92151..b898876 100644
--- a/repos/managedsave/managedsave.py
+++ b/repos/managedsave/managedsave.py
@@ -2,6 +2,8 @@
 
 import os
 import math
+import thread
+import time
 
 import libvirt
 from libvirt import libvirtError
@@ -39,39 +41,42 @@ def check_savefile_create(*args):
         logger.info("managed save file exists")
         return True
 
-def compare_cachedfile(cachebefore, cacheafter):
-    """Compare cached value before managed save and its value after
-    managed save """
-
-    diff = cacheafter - cachebefore
-    logger.info("diff is %s " % diff)
-    percent = math.fabs(diff)/cachebefore
-    logger.info("diff percent is %s " % percent)
-    if percent < 0.05:
-        return True
-    else:
-        return False
-
-def get_cachevalue():
-    """Get the file system cached value """
-
-    cmds = "head -n4 /proc/meminfo|grep Cached|awk '{print $2}'"
-    (status, output) = utils.exec_cmd(cmds, shell=True)
-    if status != 0:
-        logger.error("Fail to run cmd line to get cache")
-        return 1
+def get_fileflags():
+    """Get the file flags of managed save file"""
+    cmds = "cat /proc/$(lsof -w /var/lib/libvirt/qemu/save/"+guestname+".save"\
+    "|awk '/libvirt_i/{print $2}')/fdinfo/1|grep flags|awk '{print $NF}'"
+    global fileflags
+    while True:
+	(status, output) = utils.exec_cmd(cmds, shell=True)
+	if status == 0:
+	    for i in range(len(output)):
+		logger.info("The flags of saved file %s" % output[i])
+		fileflags = output[i][-5]
+	else:
+	    logger.error("Fail to get the flags of saved file")
+	    return 1
+
+    thread.exit_thread()
+
+def check_fileflag(fileflags):
+    """Check the file flags of managed save file if include O_DIRECT"""
+    if int(fileflags) == 4:
+	logger.info("file flags include O_DIRECT")
+	return True
     else:
-        logger.debug(output[0])
-    cachevalue= int(output[0])
-    return cachevalue
+	logger.error("file flags doesn't include O_DIRECT")
+	return False
 
 def managedsave(params):
     """Managed save a running domain"""
 
     global logger
     logger = params['logger']
+    global guestname
     guestname = params['guestname']
     flags = params ['flags']
+    global fileflags
+    fileflags = ''
     #Save given flags to sharedmod.data
     sharedmod.data['flagsave'] = flags
 
@@ -122,17 +127,14 @@ def managedsave(params):
 
         #If given flags include bypass-cache,check if bypass file system cache
         if flagn % 2 == 1:
-            logger.info("Given flags include --bypass-cache")
-            os.system('echo 3 > /proc/sys/vm/drop_caches')
-            cache_before = get_cachevalue()
-            logger.info("Cached value before managedsave is %s" % cache_before)
+            logger.info("Given flags include --bypass-cache")            
+	    thread.start_new_thread(get_fileflags,())
 
+	    # Guarantee get_fileflags shell has run before managed save
+	    time.sleep(5)
             domobj.managedSave(flagn)
 
-            cache_after = get_cachevalue()
-            logger.info("Cached value after managedsave is %s" % cache_after)
-
-            if compare_cachedfile(cache_before, cache_after):
+	    if check_fileflag(fileflags):
                 logger.info("Bypass file system cache successfully")
             else:
                 logger.error("Bypass file system cache failed")
-- 
1.7.7.6