fix befd471ef7dcf46b regression

control_port can be zero.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
doc/iscsi: typo fix in doc/README.iscsi

Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
tgtadm: Correct mode names in the option error message

When an error option is specified for some mode and operation,
tgtadm outputs an error message which contains the mode name.
But some of the mode names are obviously wrong so the patch fixes
them.

Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
tgtadm: display unsupported operation name explicitly

When we specify an unsupported operation type for some mode,
tgtadm will display the error message which contains the
unsupported operation type value. The patch changes to
display the operation name which is more explicit. Also
change the word 'option' to 'operation'.

Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
tgtadm: fix a bug to read the response buffer

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
iser: Add Discovery support

Add support to handle TEXT PDU, such as SendTargets which are used for
running iscsi discovery over iser.

Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Alexander Nezhinsky <nezhinsky@gmail.com>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>