File lio-utils-retry-enabling-fileio-target.patch of Package lio-utils.2657

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File lio-utils-retry-enabling-fileio-target.patch of Package lio-utils.2657

From: Lee Duncan
Date: Thu Nov 19 14:15:22 PST 2015
Subject: retrying enabling FILEIO target
Reference: bsc#940636

When trying to enable a newly create target in
sysfs, if we are too fast, the target might not
yet be fully set, since the time between creating
the target (with a mkdir in sysfs) and the time
when the target is fully set up is indetermanent.

This patch enables 3 retries, at one second each,
when trying to enable a target.

---
 tcm-py/tcm_fileio.py |   34 ++++++++++++++++++++++++++++++----
 1 file changed, 30 insertions(+), 4 deletions(-)

--- a/tcm-py/tcm_fileio.py
+++ b/tcm-py/tcm_fileio.py
@@ -3,10 +3,37 @@
 import os
 import subprocess as sub
 import string, re 
+import time
 from optparse import OptionParser
 
 tcm_root = "/sys/kernel/config/target/core"
 
+def write_with_retries(attr_value, attr_path, newline=True, retries=5):
+    """
+    Write an attribute value to an attribute path, followed by an
+    optional newline, with retries if needed. Return boolean
+    success or failure.
+    """
+    success = False
+    while 1:
+        try:
+            with open(attr_path, 'w') as attr_file:
+	        if newline:
+		    print >>attr_file, attr_value
+		else:
+		    print >>attr_file, attr_value,
+            success=True
+            break
+        except Exception, e:
+#	    print "DEBUG: write failed", e
+            retries = retries - 1
+            if not retries:
+                break
+            time.sleep(1)
+#    print "DEBUG: write '%s' to '%s': success=%s, retries left=%d" % \
+#    	(attr_value, attr_path, success, retries)
+    return success
+
 def createvirtdev(path, params):
 	
 #	print "Calling fileio createvirtdev: path " + path
@@ -40,13 +67,12 @@ def createvirtdev(path, params):
 		print "FILEIO: createvirtdev failed for control_opt with " + params[0]
 		return -1
 
-	enable_opt = "echo 1 > " +  cfs_path + "enable"	
-#	print "Calling enable_opt " + enable_opt
-	ret = os.system(enable_opt)
-	if ret:
+	if not write_with_retries("1", cfs_path + "enable"):
 		print "FILEIO: createvirtdev failed for enable_opt with " + params[0]
 		return -1
 
+	return 0
+
 def fd_freevirtdev():
 	pass

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File lio-utils-retry-enabling-fileio-target.patch of Package lio-utils.2657

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