Created attachment 1433197 [details]
proposed patch to fix the issue

== Description of problem:
When fence_scsi stonith device configuration is updated the content of '/var/run/cluster/fence_scsi.dev'
gets partially duplicated and grows over time.

== Version-Release number of selected component (if applicable):
fence-agents-scsi-4.0.11-86.el7.x86_64

== How reproducible:
always

== Steps to Reproduce:
1. Create fence_scsi stonith device in pacemaker cluster with at least 2 devices in 'device' attribute
  # pcs stonith create scsi fence_scsi devices="/dev/sdb,/dev/sdc"
2. Update the 'scsi' stonith device by adding a new disk to list
  # pcs stonith update scsi devices="/dev/sdb,/dev/sdc,/dev/sdd"

== Actual results:
Content of the file '/var/run/cluster/fence_scsi.dev'
# cat /var/run/cluster/fence_scsi.dev
/dev/sdb
/dev/sdc
/dev/sdc
/dev/sdd

== Expected results:
Content of the file '/var/run/cluster/fence_scsi.dev'
# cat /var/run/cluster/fence_scsi.dev
/dev/sdb
/dev/sdc
/dev/sdd

== Additional info:
Running more updates results in more duplicate entries inside the file.

For example in above situation adding another disk would result in following content:
# pcs stonith update scsi devices="/dev/sdb,/dev/sdc,/dev/sdd,/dev/sde"
# cat /var/run/cluster/fence_scsi.dev
/dev/sdb
/dev/sdc
/dev/sdc
/dev/sdd
/dev/sdc
/dev/sdd
/dev/sde

It seems that the function responsible for matching the device name doesn't match properly.
Applying following change to /usr/sbin/fence_scsi seems to resolve the problem and make the
devices to match properly.

--- /usr/sbin/fence_scsi	2018-02-07 16:53:44.000000000 +0100
+++ /usr/sbin/fence_scsi	2018-05-08 14:36:57.168000000 +0200
@@ -240,7 +240,7 @@
 	except IOError:
 		fail_usage("Failed: Cannot open file \""+ file_path + "\"")
 	out = f.read()
-	if not re.search(r"^" + dev + "\s+", out):
+	if not re.search(r"^" + dev + "\s+", out, flags=re.MULTILINE):
 		f.write(dev + "\n")
 	f.close()