Description of problem:
=======================
Had a 4node cluster with glusterfs-3.8.4-54.12 and gluster-block-0.2.1-20 and tcmu-runner-1.2.0-20. Was verifying BZ 1470955 when I tried executing a block create with size specified in bytes (for e.g., 512B). And the block creation failed. Below traceback was seen in /var/log/messages. Size specified (>512) in just numbers succeeds. Size (>512) suffixed with 'B' fails with a traceback.

Version-Release number of selected component (if applicable):
==============================================================[root@dhcp35-120 ~]# rpm -qa | grep gluster
glusterfs-cli-3.8.4-54.12.el7rhgs.x86_64
glusterfs-libs-3.8.4-54.12.el7rhgs.x86_64
glusterfs-rdma-3.8.4-54.12.el7rhgs.x86_64
libvirt-daemon-driver-storage-gluster-3.9.0-14.el7_5.5.x86_64
vdsm-gluster-4.17.33-1.2.el7rhgs.noarch
gluster-nagios-addons-0.2.10-2.el7rhgs.x86_64
glusterfs-api-3.8.4-54.12.el7rhgs.x86_64
glusterfs-geo-replication-3.8.4-54.12.el7rhgs.x86_64
gluster-nagios-common-0.2.4-1.el7rhgs.noarch
glusterfs-client-xlators-3.8.4-54.12.el7rhgs.x86_64
glusterfs-server-3.8.4-54.12.el7rhgs.x86_64
gluster-block-0.2.1-20.el7rhgs.x86_64
glusterfs-3.8.4-54.12.el7rhgs.x86_64
python-gluster-3.8.4-54.12.el7rhgs.noarch
glusterfs-fuse-3.8.4-54.12.el7rhgs.x86_64
[root@dhcp35-120 ~]# rpm -qa | grep tcmu
libtcmu-1.2.0-20.el7rhgs.x86_64
tcmu-runner-1.2.0-20.el7rhgs.x86_64
[root@dhcp35-120 ~]# rpm -qa | grep targetcli
targetcli-2.1.fb46-6.el7_5.noarch
[root@dhcp35-120 ~]# rpm -qa | grep configshell
python-configshell-1.1.fb23-4.el7_5.noarch
[root@dhcp35-120 ~]# rpm -qa | grep rtslib
python-rtslib-2.1.fb63-12.el7_5.noarch
[root@dhcp35-120 ~]# 


How reproducible:
=================
2:2


Steps to Reproduce:
====================
1. Have a 3 node cluster with brick mux enabled, create a X3 volume, and set the volume option to group 'gluster-block'.
2. Execute 'gluster-block create <volname>/<blockname> ha 2 <node1>,<node2>  1000B'


Actual results:
===============
Block create fails.
Traceback seen in /var/log/messages

Sosreports and gluster-blockd logs will be copied at: http://rhsqe-repo.lab.eng.blr.redhat.com/sosreports/swetas/<bugnumber>

Expected results:
=================
Block create should succeed, as long as the size specified is greater than 512bytes. 'B' if it stands for 'bytes' should be accepted, or at least handled gracefully, if it stands for something else. 


Additional info:
================

Jun 26 15:05:29 dhcp35-147 tcmu-runner[15650]: add_device:486 : handler open failed for uio2
Jun 26 15:05:29 dhcp35-147 tcmu-runner: 2018-06-26 15:05:29.966 15650 [ERROR] add_device:486 : handler open failed for uio2
Jun 26 15:05:30 dhcp35-147 python: detected unhandled Python exception in '/usr/bin/targetcli'
Jun 26 15:05:30 dhcp35-147 abrt-server: Package 'targetcli' isn't signed with proper key
Jun 26 15:05:30 dhcp35-147 abrt-server: 'post-create' on '/var/spool/abrt/Python-2018-06-26-15:05:30-1031' exited with 1
Jun 26 15:05:30 dhcp35-147 abrt-server: Deleting problem directory '/var/spool/abrt/Python-2018-06-26-15:05:30-1031'
Jun 26 15:05:30 dhcp35-147 gluster-blockd: Traceback (most recent call last):
Jun 26 15:05:30 dhcp35-147 gluster-blockd: File "/usr/bin/targetcli", line 122, in <module>
Jun 26 15:05:30 dhcp35-147 gluster-blockd: main()
Jun 26 15:05:30 dhcp35-147 gluster-blockd: File "/usr/bin/targetcli", line 112, in main
Jun 26 15:05:30 dhcp35-147 gluster-blockd: shell.run_interactive()
Jun 26 15:05:30 dhcp35-147 gluster-blockd: File "/usr/lib/python2.7/site-packages/configshell_fb/shell.py", line 905, in run_interactive
Jun 26 15:05:30 dhcp35-147 gluster-blockd: self._cli_loop()
Jun 26 15:05:30 dhcp35-147 gluster-blockd: File "/usr/lib/python2.7/site-packages/configshell_fb/shell.py", line 734, in _cli_loop
Jun 26 15:05:30 dhcp35-147 gluster-blockd: self.run_cmdline(cmdline)
Jun 26 15:05:30 dhcp35-147 gluster-blockd: File "/usr/lib/python2.7/site-packages/configshell_fb/shell.py", line 848, in run_cmdline
Jun 26 15:05:30 dhcp35-147 gluster-blockd: self._execute_command(path, command, pparams, kparams)
Jun 26 15:05:30 dhcp35-147 gluster-blockd: File "/usr/lib/python2.7/site-packages/configshell_fb/shell.py", line 823, in _execute_command
Jun 26 15:05:30 dhcp35-147 gluster-blockd: result = target.execute_command(command, pparams, kparams)
Jun 26 15:05:30 dhcp35-147 gluster-blockd: File "/usr/lib/python2.7/site-packages/configshell_fb/node.py", line 1406, in execute_command
Jun 26 15:05:30 dhcp35-147 gluster-blockd: return method(*pparams, **kparams)
Jun 26 15:05:30 dhcp35-147 gluster-blockd: File "/usr/lib/python2.7/site-packages/targetcli/ui_backstore.py", line 610, in ui_command_create
Jun 26 15:05:30 dhcp35-147 gluster-blockd: hw_max_sectors=hw_max_sectors, control=control)
Jun 26 15:05:30 dhcp35-147 gluster-blockd: File "/usr/lib/python2.7/site-packages/rtslib_fb/tcm.py", line 823, in __init__
Jun 26 15:05:30 dhcp35-147 gluster-blockd: self._configure(config, size, wwn, hw_max_sectors, control)
Jun 26 15:05:30 dhcp35-147 gluster-blockd: File "/usr/lib/python2.7/site-packages/rtslib_fb/tcm.py", line 841, in _configure
Jun 26 15:05:30 dhcp35-147 gluster-blockd: self._enable()
Jun 26 15:05:30 dhcp35-147 gluster-blockd: File "/usr/lib/python2.7/site-packages/rtslib_fb/tcm.py", line 171, in _enable
Jun 26 15:05:30 dhcp35-147 gluster-blockd: fwrite(path, "1\n")
Jun 26 15:05:30 dhcp35-147 gluster-blockd: File "/usr/lib/python2.7/site-packages/rtslib_fb/utils.py", line 79, in fwrite
Jun 26 15:05:30 dhcp35-147 gluster-blockd: file_fd.write(str(string))
Jun 26 15:05:30 dhcp35-147 gluster-blockd: IOError: [Errno 2] No such file or directory