[libvirt] Re: [Patch v0.4] iSCSI Multi-IQN (Libvirt Support)

[Dave Allan]

Shyam_Iyer at Dell.com wrote:
> 
>> -----Original Message-----
>> From: Daniel P. Berrange [mailto:berrange at redhat.com]
>> Sent: Tuesday, November 17, 2009 11:21 PM
>> To: Dave Allan
>> Cc: Bellad, Sudhir; libvir-list at redhat.com; Iyer, Shyam; Domsch, Matt;
>> KM, Paniraja
>> Subject: Re: [libvirt] Re: [Patch v0.4] iSCSI Multi-IQN (Libvirt
>> Support)
>>
>> On Mon, Nov 16, 2009 at 01:58:08PM -0500, Dave Allan wrote:
>>> diff --git a/src/storage_backend_iscsi.c
>> b/src/storage_backend_iscsi.c
>>> index b516add..1fb21a5 100644
>>> --- a/src/storage_backend_iscsi.c
>>> +++ b/src/storage_backend_iscsi.c
>>> @@ -39,6 +39,10 @@
>>>  #include "storage_backend_iscsi.h"
>>>  #include "util.h"
>>>  #include "memory.h"
>>> +#include <sys/types.h>
>>> +#include <sys/stat.h>
>>> +#include <fcntl.h>
>>> +#include <unistd.h>
>>>
>>>  #define VIR_FROM_THIS VIR_FROM_STORAGE
>>>
>>> @@ -159,13 +163,54 @@ virStorageBackendISCSIConnection(virConnectPtr
>> conn,
>>>                                   const char *portal,
>>>                                   const char *action)
>>>  {
>>> -    const char *const cmdargv[] = {
>>> -        ISCSIADM, "--mode", "node", "--portal", portal,
>>> -        "--targetname", pool->def->source.devices[0].path, action,
>> NULL
>>> -    };
>>> -
>>> -    if (virRun(conn, cmdargv, NULL) < 0)
>>> -        return -1;
>>> +    DIR *dir;
>>> +    struct dirent *entry;
>>> +
>>> +
>>> +	if (pool->def->source.initiator.iqnname != NULL) {
>>>
>>> What's the point of this loop?  At best, it's unneeded complexity,
> at
>>> worst it will match multiple interface names which will create the
>>> multiple sessions per pool scenario that I explicitly want to avoid.
>>>
>>> Secondly, if you want to do some sort of validation of the iqn, why
>> are
>>> you reading from a hardcoded directory?  Can you use the output of
>>> iscsiadm?  That is likely to be a more stable interface than the
>>> directory which I would expect is a compile time option to the iscsi
>>> initiator.
>> I'm really wondering much the same here - I don't see the purpose
>> in iterating over this directory. The iqn given in the XML ought
>> to be able to be passed straight to iscsadm's -I parameter
>>
> 
> Iscsiadm's -I parameter takes iface name as the parameter value and not
> the iqn name.
> 
> So I believe this approach could be taken -
> 
> 1) Get the iqn for the corresponding iface name using the following
> command
> #iscsiadm -m iface
> 
> Example output:
> 
> [root at localhost libvirt-0.7.1-15-org]# iscsiadm -m iface
> default tcp,default,default,unknown
> iser iser,default,default,unknown
> bnx2i bnx2i,default,default,unknown
> iface1 tcp,default,default,iqn.1994-05.com.fedora:iqnBellad
> iface3 tcp,default,default,iqn.dell
> iface0 tcp,unknown,unknown,iqn.1994-05.com.fedora:iqnSudhir
> 
> The last value is the initiator iqn name.
> 

Oh, ok, that makes sense.  If you use the output of iscsiadm and STREQ 
on a portion of the output instead of strstr to match the iqn, that 
should be fine.  You should also break out of the loop once you've 
matched the iqn.

Dave